JP7067071B2 - Manufacturing method for pretreatment liquid, ink set, and printed matter - Google Patents

Description

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a high-quality image having sufficient density without causing image defects such as bleeding and color unevenness and cracking regardless of the base material, and it is possible to obtain a high-quality image with sufficient density, and to adhere to the coating device or print. The present invention relates to a pretreatment liquid that does not cause set-off when the subsequent base materials are stacked and has excellent storage stability, and an ink set composed of the pretreatment liquid and inkjet ink. The present invention also relates to a method for producing a printed matter using the ink set.

Inkjet printing is a recording method in which droplets of inkjet ink ejected from an inkjet head are directly applied to a substrate to form characters and images. Compared to conventional plate-based printing such as offset printing and gravure printing, it has the features of being able to support variable printing without the need for plate making, easy operation and adjustment of the printing device, and low noise during printing. In recent years, its demand has been increasing for industrial applications as well as for home use.

Inkjet inks used for inkjet printing are classified into solvent type, water-based type, UV curable type and the like according to their composition. On the other hand, in recent years, there has been an accelerating movement to regulate the use of organic solvents and photosensitive monomers that are harmful to humans and the environment, and from solvent-based inks and UV-curable inks that use these materials to water-based inks. There is a growing demand for replacement of the ink.

The water-based (mold) inkjet ink contains water as a main component, and a water-soluble organic solvent such as glycerin or glycol is added to control the wettability and drying property with respect to the base material. Further, when a character or image pattern is printed (imposed) on a base material using an aqueous inkjet ink composed of these liquid components, the liquid component permeates into the base material and / or evaporates from the base material. Is dried and fixed on the substrate.

On the other hand, there are various base materials used in inkjet printing, from those with high permeability such as high-quality paper and recycled paper to those with low (no) permeability such as coated paper, art paper, and plastic film. do. In general, water-based (mold) inkjet inks can print on highly permeable paper such as wood-free paper and recycled paper with image quality that is practical to some extent, whereas coated paper, art paper, and plastics. It has been difficult to obtain a practical level of image quality for a film having low (no) permeability because bleeding occurs between colors and deterioration of image quality occurs. In order to further expand the demand for inkjet printing, the development of water-based inkjet inks that can be applied to various substrates has become a major issue for those skilled in the art.

As a measure to solve the above-mentioned problems, pretreatment liquid treatment for a base material is known. Generally, as a pretreatment liquid for water-based inkjet inks, those that form a layer (ink receiving layer) that absorbs liquid components in the inkjet ink to improve dryness (see Patent Documents 1 to 4), coloring materials, and the like. By intentionally aggregating solid components contained in ink jet ink such as resin to form a layer (ink agglomerate layer) that prevents bleeding and color unevenness between droplets and improves image quality (see Patent Documents 5 to 6). ) Are known.

However, in the case of the ink receiving layer, for example, when receiving a large amount of ink at one time, the base material is wavy, curled (rounded), image cracked due to swelling of the ink receiving layer, and bleeding and color due to excess of the acceptable amount. Unevenness may occur due to the absorption of ink components into the receiving layer, resulting in a decrease in density. On the contrary, in the case of the ink agglomerate layer, since the absorption of the liquid component basically does not occur, these phenomena are unlikely to occur, but if the ink agglomerate layer does not have a uniform film thickness, the image quality deteriorates. Or, there is a risk of problems associated with partial deterioration of dryness. That is, in the region where the film thickness of the ink cohesive layer is small, the ink coagulation effect is small, and bleeding and color unevenness occur. On the contrary, in the region where the film thickness is large, bleeding and color unevenness can be suppressed, but the dryness of the pretreatment liquid and the ink applied on the pretreatment liquid is lowered, so that the pretreatment liquid and the ink are contained in the coating device. Set-off occurs when the substrates adhere to each other or when the substrates are stacked after printing. In particular, in the case of high-speed, high-recording resolution printing, these problems are likely to occur, which may lead to a large deterioration in quality. Therefore, when a pretreatment liquid that forms an ink agglomerate layer is adopted, uniform coating thereof becomes an important issue.

In order to ensure uniform coatability of the pretreatment liquid, the wettability of the base material has been improved by adding an organic solvent, but it has not been sufficient. For example, Patent Document 5 discloses a pretreatment liquid containing a multivalent metal ion and an organic solvent. However, since the organic solvent used in the above document has a high surface tension such as glycerin, the pretreatment liquid cannot be uniformly applied, especially when printing at high speed and high recording resolution, and the above image quality is obtained. There is a risk of deterioration and poor drying properties.

As described above, with the conventional technique, high-quality image quality can be obtained regardless of the base material used even in high-speed, high-recording-resolution inkjet printing, and adhesion to the inside of the coating device and after printing. There was no pretreatment liquid that did not cause set-off when the base materials of No. 1 were stacked.

Further, so far, little attention has been paid to the storage stability of the pretreatment liquid that forms the ink agglomerate layer containing the metal salt. For example, Patent Document 6 discloses a pretreatment liquid containing a multivalent metal ion and an organic solvent, and storage stability is mentioned as one of its effects. However, the above-mentioned document does not specifically describe a method or basis for improving storage stability.

Japanese Unexamined Patent Publication No. 2000-238422 Japanese Unexamined Patent Publication No. 2000-335084 Japanese Unexamined Patent Publication No. 2012-131108 Japanese Unexamined Patent Publication No. 2009-241304 Japanese Unexamined Patent Publication No. 11-010856 Japanese Unexamined Patent Publication No. 2004-276253

The present invention has been made to solve the above problems, and an object thereof is to prevent image defects and cracks such as bleeding and color unevenness in high-speed and high-resolution inkjet printing regardless of the base material used. It is possible to obtain a high-quality image with sufficient density without causing it, and it does not adhere to the inside of the coating equipment or set-off when the base materials after printing are stacked, and it is stable in storage. It is intended to provide a pretreatment liquid having excellent properties, and an ink set including the pretreatment liquid and an inkjet ink. The present invention further provides a manufacturing method effective for solving the above-mentioned problems in manufacturing a printed matter using the above-mentioned ink set.

As a result of diligent research to solve the above problems, the present inventors can solve the above problems by using a pretreatment liquid containing a specific amount of a specific material and an ink set consisting of the pretreatment liquid and an inkjet ink. And completed the present invention.

That is, the present invention is an ink set for a paper base material or a film base material, which comprises a pretreatment liquid used in a method of printing in contact with a base material and a water-based inkjet ink.
The water-based inkjet ink contains a pigment, a water-soluble organic solvent, a water-soluble binder resin, and water.
The pretreatment liquid contains a dissolved inorganic metal salt and / or an organic metal salt, an organic solvent, a water-soluble binder resin, a surfactant, and water.
The metal ion derived from the inorganic metal salt and / or the organometallic salt contains a polyvalent metal ion, and the content of the polyvalent metal ion is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid. ,
The organic solvent contains a compound containing one or more hydroxyl groups in its molecular structure (excluding those which are surfactants) , and the content of the organic solvent having a boiling point of 180 ° C. or higher is the total amount of the pretreatment liquid. It is 15% by weight or less with respect to
Compounds containing one or more hydroxyl groups in the molecular structure include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1. -Butanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentane Dire, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3 -Propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1 , 3-Propanediol, 2-methylpentane-2,4-diol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, diethylene glycol, triethylene glycol, polyethylene glycol # 200, polyethylene glycol # 400 , Ethylene Glycol # 600, Dipropylene Glycol, Butylene Glycol, Dibutylene Glycol, Glycerin, Ethylene Glycol Monoethyl Ether, Ethylene Glycol Monobutyl Ether, Diethylene Glycol Monomethyl Ether, Diethylene Glycol Monoethyl Ether, Diethylene Glycol Monopropyl Ether, Diethylene Glycol Monobutyl Ether, Diethylene Glycol Mono Pentyl Ether, Diethylene Glycol Monohexyl Ether, Triethylene Glycol Monomethyl Ether, Triethylene Glycol Monoethyl Ether, Triethylene Glycol Monopropyl Ether, Triethylene Glycol Monobutyl Ether, Tetraethylene Glycol Monomethyl Ether, Tetraethylene Glycol Monoethyl Ether, Tetraethylene Glycol Monobutyl Ether, Ethylene Glycol Monomethyl Ether, Ethylene Glycol Monoethyl Ether, Ethylene Glycol Monopropyl Ether, Ethylene Glycol Monobutyl Ether, Dipropylene Glycol Monomethyl Ether, Dipropylene Glycol Monoethyl Ether, Dipropylene Glycol Monopropyl Ether, Tripropi One or more compounds selected from the group consisting of reneglycol monomethyl ether and tripropylene glycol monoethyl ether.
The number average molecular weight (Mn) of the water-soluble binder resin contained in the pretreatment liquid is 3,000 to 90,000.
The surfactant is a siloxane-based and / or acetylene-based surfactant.
The present invention relates to an ink set, characterized in that the acid value of the water-soluble binder resin contained in the water-based inkjet ink is 10 to 80 mgKOH / g .

Further, the present invention is an ink set for a paper base material or a film base material, which comprises a pretreatment liquid used in a method of printing without contact with a base material and a water-based inkjet ink.
The water-based inkjet ink contains a pigment, a water-soluble organic solvent, a water-soluble binder resin, and water.
The pretreatment liquid contains a dissolved inorganic metal salt and / or an organic metal salt, an organic solvent, a water-soluble binder resin, a surfactant, and water.
The metal ion derived from the inorganic metal salt and / or the organometallic salt contains a polyvalent metal ion, and the content of the polyvalent metal ion is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid. ,
The organic solvent contains a compound containing one or more hydroxyl groups in its molecular structure (excluding those which are surfactants), and the content of the organic solvent having a boiling point of 180 ° C. or higher is the total amount of the pretreatment liquid. It is 15% by weight or less with respect to
Compounds containing one or more hydroxyl groups in the molecular structure include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1. -Butanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentane Dire, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3 -Propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1 , 3-Propanediol, 2-methylpentane-2,4-diol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, diethylene glycol, triethylene glycol, polyethylene glycol # 200, polyethylene glycol # 400 , Ethylene Glycol # 600, Dipropylene Glycol, Butylene Glycol, Dibutylene Glycol, Glycerin, Ethylene Glycol Monoethyl Ether, Ethylene Glycol Monobutyl Ether, Diethylene Glycol Monomethyl Ether, Diethylene Glycol Monoethyl Ether, Diethylene Glycol Monopropyl Ether, Diethylene Glycol Monobutyl Ether, Diethylene Glycol Mono Pentyl Ether, Diethylene Glycol Monohexyl Ether, Triethylene Glycol Monomethyl Ether, Triethylene Glycol Monoethyl Ether, Triethylene Glycol Monopropyl Ether, Triethylene Glycol Monobutyl Ether, Tetraethylene Glycol Monomethyl Ether, Tetraethylene Glycol Monoethyl Ether, Tetraethylene Glycol Monobutyl Ether, Ethylene Glycol Monomethyl Ether, Ethylene Glycol Monoethyl Ether, Ethylene Glycol Monopropyl Ether, Ethylene Glycol Monobutyl Ether, Dipropylene Glycol Monomethyl Ether, Dipropylene Glycol Monoethyl Ether, Dipropylene Glycol Monopropyl Ether, Tripropi One or more compounds selected from the group consisting of reneglycol monomethyl ether and tripropylene glycol monoethyl ether.
The weight average molecular weight (Mw) of the water-soluble binder resin contained in the pretreatment liquid is 3,000 to 50,000.
The surfactant is a siloxane-based and / or acetylene-based surfactant.
The present invention relates to an ink set, characterized in that the acid value of the water-soluble binder resin contained in the water-based inkjet ink is 10 to 80 mgKOH / g .

The present invention also relates to the ink set, wherein the water-soluble binder resin contained in the pretreatment liquid contains a nonionic water-soluble resin.
The present invention also relates to the above ink set, wherein the compound containing one or more hydroxyl groups in the molecular structure contains monohydric alcohols.
Further, in the present invention, the content of the organic solvent having a surface tension of 20 to 32 mN / m at 25 ° C. in the pretreatment liquid is 35 to 100% by weight based on the total amount of the organic solvent in the pretreatment liquid. The present invention relates to the above-mentioned ink set, which is characterized by being present.

The present invention is also characterized in that the weight ratio of the content of the binder resin to the content of the metal ion derived from the inorganic metal salt and / or the organometallic salt is more than 0 and less than 20. Regarding.

The present invention also relates to the above ink set, which is characterized in that the surface tension of the pretreatment liquid is 20 to 45 mN / m.

Further, in the present invention, the water-soluble organic solvent contained in the water-based inkjet ink contains two or more kinds of glycol ether-based solvent and / or alkyl polyol-based solvent having a boiling point of 180 ° C. or higher and 250 ° C. or lower at 1 atm. The present invention relates to the above-mentioned ink set.

Further, the present invention is characterized in that the water-based inkjet ink contains 0% by weight or more and less than 10% by weight of a water-soluble organic solvent having a boiling point of 240 ° C. or higher at 1 atm with respect to the total amount of the water-based inkjet ink. , Regarding the above ink set.

The present invention also relates to the ink set, which is characterized in that the water-based inkjet ink does not substantially contain a polymerizable monomer .

Further, the present invention is characterized in that the water-based inkjet ink contains 0% by weight or more and less than 20% by weight of a water-soluble organic solvent having a boiling point of 210 ° C. or higher at 1 atm with respect to the total amount of the water-based inkjet ink. , Regarding the above ink set.

The present invention also relates to the ink set, wherein the water-based inkjet ink contains a pigment in an amount of 2% by weight or more and less than 15% by weight based on the total amount of the water-based inkjet ink.

Further, the present invention is a method for producing a water-based inkjet ink printed matter using the ink set described above, which comprises a step of applying a pretreatment liquid to a substrate conveyed at a speed of 30 m / min or more, and the pretreatment liquid. A method for producing a water-based inkjet ink printed matter, which comprises a step of applying the water-based inkjet ink to the portion to which the ink jet ink is applied by a one-pass printing method, wherein the base material is a paper base material or a film base material. Regarding.

The present invention also relates to a method for producing the water-based inkjet ink printed matter, which is characterized in that the amount of the pretreatment liquid applied is 1 to 25 g / m ² .

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a high-quality image having a sufficient density without causing image defects such as bleeding and color unevenness and cracks regardless of the base material used, and it is possible to obtain high-quality images with sufficient density and adhere to the inside of a coating device. It has become possible to provide a pretreatment liquid that does not cause set-off when the substrates after printing are stacked and has excellent storage stability, and an ink set consisting of the pretreatment liquid and inkjet ink. .. Further, in manufacturing a printed matter using the ink set, it has become possible to provide an effective manufacturing method for solving the above-mentioned problems.

Hereinafter, preferred embodiments of the present invention will be described in detail. The embodiments described below describe an example of the present invention. The present invention is not limited to the following embodiments, and includes modifications that are carried out without changing the gist of the present invention.

The pretreatment liquid of the present invention contains an inorganic metal salt and / or an organic metal salt in a dissolved state, and the metal ion derived from the inorganic metal salt and / or the organic metal salt contains a polyvalent metal ion, and the polyvalent metal ion is contained. The content of valent metal ions is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid, and contains an organic solvent containing a compound containing one or more hydroxyl groups in the molecular structure, and has a boiling point. The content of the organic solvent at 180 ° C. or higher is 15% by weight or less. As described in the prior art, the combined use of an organometallic salt and / or an organometallic salt and an organic solvent has been conventionally performed, but in the present invention, a specific amount of polyvalent metal ion is contained and the organometallic solvent is contained. Its characteristics are that the structure of the organic solvent used together and the upper limit of the high boiling point organic solvent are specified. The effect will be described below.

The pretreatment liquid of the present invention is applied onto a base material before printing the inkjet ink, and forms an ink cohesive layer on the base material. The inorganic metal salt and / or the organic metal salt contained in the pretreatment liquid is ionized in the presence of water or a compound having one or more hydroxyl groups in the molecular structure, and the water-based inkjet ink is printed on the pretreatment liquid. A high concentration of metal cation components will be present in the layer. This metal cation component causes anion-cation interaction and adsorption equilibrium transfer with respect to an anion-charged solid component such as a pigment or a resin that exists in a state of being dissolved and / or dispersed in an inkjet ink. , Dissolves and / or disperses, and suppresses color mixing between pigments. Further, the inkjet ink can be printed before the pretreatment liquid of the present invention dries. In that case, the mixing of the inkjet ink and the pretreatment liquid changes the dissolution equilibrium and adsorption equilibrium of the solid component. , The dissolution and / or dispersion function of the solid component can be reduced.

The metal ion derived from the inorganic metal salt and / or the organometallic salt used in the present invention contains a polyvalent metal ion, and the content of the polyvalent metal ion is 2% by weight or more based on the total amount of the pretreatment liquid. It is less than% by weight. Among the metal ions, the polyvalent metal ion has a higher reaction rate of anion-cation interaction and adsorption equilibrium transfer than the monovalent metal ion, and its ability is also high. However, as a matter of course, when the content of the polyvalent metal ion is too small, the ability to cause the anion-cation interaction and the adsorption equilibrium transfer is poor, so that bleeding and color unevenness occur. Bleeding and color unevenness can be suppressed by increasing the content of polyvalent metal ions, but on the other hand, when the content of polyvalent metal ions is excessive, the present inventors have printed matter depending on the substrate used. It was found that the image quality and dryness of the product deteriorated. Although the detailed reason is not clear, the excess amount of polyvalent metal ions deteriorates the wettability of the pretreatment liquid to the substrate, causing uneven coating and varying the degree of aggregation on the printed surface. It is also considered that the boiling point elevation phenomenon caused by the inorganic metal salt and / or the organic metal salt occurred.

Therefore, in the present invention, the above problem is solved by setting the content of the multivalent metal ion to 2% by weight or more and 8% by weight or less. That is, by keeping the content of the polyvalent metal ion within the above range, the wettability of the pretreatment liquid to the substrate is ensured while suppressing bleeding and color unevenness, and the inorganic metal salt and / or the organometallic salt. The boiling point elevation caused by the above is also minimized.

On the other hand, in order for the pretreatment liquid of the present invention to function appropriately regardless of the base material type, the wettability of the pretreatment liquid is ensured for various base materials, and the liquid absorption characteristics of the base material are improved. Therefore, it is necessary to develop excellent dryness. Therefore, in the pretreatment liquid of the present invention, by using an organic solvent as an essential component, the surface tension of the pretreatment liquid is reduced, and uniform coating on a substrate having a small surface energy is possible. Further, by reducing the content of the organic solvent having a boiling point of 180 ° C. or higher to 15% by weight or less, the residual high boiling point organic solvent in the printed matter is prevented. This suppresses adhesion to the inside of the coating device and set-off when the base materials are stacked, and enables high-speed printing regardless of the base material.

However, inorganic metal salts and / or organic metal salts containing polyvalent metal ions are inferior in solubility to salts containing monovalent metal ions. In general, an organometallic solvent has a smaller polarity than water and the salt is difficult to dissolve. Therefore, a simple combination of an organometallic salt and / or an organometallic salt containing polyvalent metal ions and an organic solvent can be preserved. The pretreatment liquid is inferior in stability.

Therefore, in the present invention, the above problem is solved by using a compound containing one or more hydroxyl groups in the molecular structure as the organic solvent. Although the detailed factor is unknown, in addition to the water molecule, a compound molecule containing one or more hydroxyl groups in the molecular structure also solvates the polyvalent metal ion, and one hydroxyl group is added to the molecular structure. It is considered that the polyvalent metal ion is compatible with other organic solvents via the compound molecule containing more than one, thereby stabilizing the entire system and thus improving the storage stability of the pretreatment liquid.

As described above, even with high-speed, high-recording-resolution inkjet printing, high-quality images can be obtained regardless of the base material, and adhesion into the coating equipment and the base material after printing are overlapped. In order to obtain a pretreatment liquid that does not cause set-off and has excellent storage stability, a combination of the components of the present invention is indispensable.

On the other hand, since the ink agglomerate layer is inferior in the ability to receive water, when a large amount of inkjet ink is applied at one time or in a short time, bleeding between inks of different colors, color unevenness, and deterioration of dryness may occur. It may adhere to the inside of the coating equipment and cause set-off when the base materials are stacked. Further, in order to obtain a high-quality image even in high-speed printing, it is necessary that the ink landing accuracy and ejection stability are excellent, and that the solid printing portion is well filled. Therefore, in the present invention, it is particularly preferable to solve the above-mentioned problems by making the composition of the inkjet ink suitable for the pretreatment liquid. Specifically, by adjusting the type and amount of the water-soluble organic solvent contained in the inkjet ink and controlling the drying property, rapid drying on the ink cohesive layer is promoted, and adhesion to the inside of the coating device and a base are promoted. It suppresses set-off when stacking materials and suppresses bleeding and color unevenness.

Subsequently, the components of the pretreatment liquid of the present invention will be described in detail below.

<Inorganic metal salt and / or organometallic salt>
The pretreatment liquid of the present invention is characterized by containing an inorganic metal salt and / or an organometallic salt in a dissolved state. In the present invention, the metal salt reduces the dissolution and / or dispersion function of the solid component in the inkjet ink on the substrate and causes the solid component to aggregate, thereby causing bleeding and color unevenness due to mixing of ink droplets. It is something to improve. Materials that exhibit this effect include cationic resins and organic acids, but compared to these materials, metal salts have a lower molecular weight, are easier to transfer cationic components, and are instantly dissolved in water. Since a cationic component that causes agglomeration of solid components is generated, when the inkjet ink is ejected onto the substrate coated with the pretreatment liquid, even with a high printing rate, it instantly reaches the top of the inkjet ink layer. The cation component can move to and cause pigment aggregation. As a result, high-quality printed matter can be obtained without bleeding or color unevenness even in high-speed printing.

In the present invention, the "dissolved state" means a state in which the inorganic metal salt and / or the organometallic salt and water are uniformly mixed to form a transparent solution. Further, whether or not it is in a dissolved state can be determined, for example, by confirming whether or not the liquid is transparent when the pretreatment liquid that has been allowed to stand at 25 ° C. for 24 hours is visually observed. When the pretreatment liquid used for the above determination contains an inorganic metal salt and / or an organometallic salt and a material other than water, a liquid in which those materials are replaced with water is prepared and evaluated.

The metal salt may be used alone or in combination of two or more. The metal salt is not particularly limited as long as it is a metal salt composed of a metal ion and an anion bonded to the metal ion. Above all, it is preferable to contain a polyvalent metal salt because it can interact with the pigment instantly, suppress bleeding, and obtain a clear image without color unevenness. In addition, as a polyvalent metal ion, at least one selected from Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Al ³⁺ , Fe ²⁺ , and Fe ³⁺ can be contained as a solid component such as a pigment or a resin. It is preferable because it is easy to cause the interaction of. Furthermore, among them, the multivalent metal ion selected from Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , and Al ³⁺ has an advantage that it has a large aggregation effect because it has a high ionization tendency and easily generates a cation component. More preferably used. In particular, the multivalent metal ion selected from Ca ²⁺ and Mg ²⁺ is extremely preferably selected because it has a small ionic radius and easily moves in the inkjet ink layer.

Specific examples of the inorganic metal salt include calcium chloride, magnesium chloride, aluminum chloride, calcium bromide, magnesium bromide, calcium nitrate, magnesium nitrate, magnesium sulfate, aluminum sulfate, calcium carbonate, magnesium carbonate and the like. It is not limited to these. Among these inorganic metal salts, chlorides and nitrates, which are generally highly soluble in water, are more preferable. Further, among these inorganic metal salts, calcium chloride and calcium nitrate are particularly preferable because they are soluble in water and interact with the components in the inkjet ink efficiently and quickly. Specific examples of the organic metal salt include, but are limited to, calcium salts, magnesium salts, nickel salts, zinc salts and the like of organic acids such as pantothenic acid, propionic acid, ascorbic acid, acetic acid and lactic acid. It's not a thing. Among these organic acid metal salts, calcium salts of lactic acid and / or acetic acid are more preferable from the viewpoint of solubility in water and interaction with the components in the inkjet ink.

The content of the metal salt in the pretreatment liquid of the present invention is preferably 2 to 8% by weight, particularly 2.5 to 5% by weight, as polyvalent metal ions with respect to the total amount of the pretreatment liquid. preferable. By keeping the metal ion content within the above range, as described above, while suppressing bleeding and color unevenness, the wettability of the pretreatment liquid to the substrate is ensured, and the inorganic metal salt and / or the organic metal The boiling point elevation caused by the salt can also be minimized. When the content of the multivalent metal ion is less than 2% by weight, the ability to cause the ink aggregation in an instant cannot be sufficiently exhibited, and bleeding and color unevenness occur, which is not preferable. On the contrary, when it exceeds 8% by weight, the wettability of the pretreatment liquid with respect to the substrate deteriorates, causing uneven coating, and the boiling point elevation phenomenon caused by the inorganic metal salt and / or the organometallic salt occurs. It is not preferable because it occurs and the drying property deteriorates. The content of the polyvalent metal ion with respect to the total amount of the pretreatment liquid is calculated by the following formula (1).

Equation (1):

(Content of multivalent metal ion) (% by weight) = WC × MM ÷ MC

In the general formula (1), WC represents the content of the inorganic metal salt and / or the organometallic salt with respect to the total amount of the pretreatment liquid, and MM is the polyvalent metal ion constituting the inorganic metal salt and / or the organometallic salt. Represents the molecular weight of, and MC represents the molecular weight of the inorganic metal salt and / or the organometallic salt.

<Organic solvent>
The pretreatment liquid of the present invention is characterized by further containing an organic solvent containing a compound containing one or more hydroxyl groups in the molecular structure, in addition to the inorganic metal salt and / or the organometallic salt. By using an organic solvent in combination, the dryness of the pretreatment liquid can be controlled, and at the same time, the wettability to the substrate during high-speed printing can be adjusted to a more suitable one, and uniform coating can be performed. .. Further, as described above, the storage stability of the pretreatment liquid is improved by using a compound containing one or more hydroxyl groups in the molecular structure.

In the present invention, the "organic solvent" refers to a solvent that is liquid at 25 ° C. Further, the surfactant described later is not included in the "organic solvent containing a compound containing one or more hydroxyl groups in the molecular structure".

Methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2- Monohydric alcohols such as butanol, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol,
1,2-Etandiol (ethylene glycol), 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-Pentanediol, 1,5-Pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 2,2-dimethyl-1,3-propanediol, 2- Methyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl- 2-propyl-1,3-propanediol, 2-methylpentane-2,4-diol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, diethylene glycol, triethylene glycol, polyethylene glycol # 200 , Polyhydric alcohols (glycols) such as polyethylene glycol # 400, polyethylene glycol # 600, dipropylene glycol, butylene glycol, dibutylene glycol, etc.
Trihydric alcohols such as glycerin,
Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl Ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether , Glycol monoalkyl ethers such as propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether. ..
In the present invention, it is preferable to select alcohols from the above exemplified compounds because they have excellent affinity with polyvalent metal ions, water molecules, and other organic solvents. Among them, in the case of the pretreatment liquid applied on the substrate by the contact method, it is preferable to use monohydric alcohols as the alcohols, and ethanol, 1-propanol, 2-propanol and 3-methoxy-1 are preferable. It is particularly preferable to contain one or more selected from -butanol and 3-methoxy-3-methyl-1-butanol. In the case of a pretreatment liquid applied onto a substrate by a non-contact printing method, it is preferable to use dihydric alcohols (glycols) as the alcohols, and 1,2-ethanediol (ethylene glycol) is preferable. ), 1,2-Propylenediol (propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol. It is particularly preferable to contain one or more of them.

The compound containing one or more hydroxyl groups in the above molecular structure may be used alone or in combination of two or more.

When the pretreatment liquid of the present invention is used in a printing method applied on a substrate by a non-contact printing method, the content of the compound containing one or more hydroxyl groups in the molecular structure is the total amount of the pretreatment liquid. It is preferably 0.1 to 20% by weight or less, more preferably 0.5 to 10% by weight, and particularly preferably 1 to 5% by weight. By keeping the content of the compound within the above range, a pretreatment liquid having both dryness, wettability and storage stability can be obtained, and stable printing for a long period of time becomes possible.
Further, in the case of the pretreatment liquid used in the printing method applied on the substrate by the non-contact printing method, the content of the compound containing one or more hydroxyl groups in the molecular structure is determined from the same viewpoint as above. It is preferably 0.1 to 40% by weight, more preferably 1 to 35% by weight, and particularly preferably 2 to 30% by weight, based on the total amount of the pretreatment liquid.

In addition, the pretreatment liquid of the present invention includes diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol butyl methyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol butyl methyl ether, and triethylene glycol. Glycoldialkyl ethers such as diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol butyl methyl ether, tetraethylene glycol diethyl ether, etc.
2-Pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, ε-caprolactam, 3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, N, N-dimethyl-β-methoxypropionamide, N, N- Dimethyl-β-ethoxypropionamide, N, N-dimethyl-β-butoxypropionamide, N, N-dimethyl-β-pentoxypropionamide, N, N-dimethyl-β-hexoxypropionamide, N, N- Dimethyl-β-heptoxypropionamide, N, N-dimethyl-β-2-ethylhexoxypropionamide, N, N-dimethyl-β-octoxypropionamide, N, N-diethyl-β-butoxypropionamide, N, N-diethyl-β-pentoxypropionamide, N, N-diethyl-β-hexoxypropionamide, N, N-diethyl-β-heptoxypropionamide, N, N-diethyl-β-octoxypropion Nitrogen-containing solvents such as amides,
Heterocyclic compounds such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone can be used.
The above organic solvent may be used alone or in combination of two or more.

The total content of the organic solvent contained in the pretreatment liquid of the present invention is preferably 0.1 to 50% by weight based on the total amount of the pretreatment liquid. By keeping the content of the organic solvent within the above range, it is possible to achieve both the dryness of the pretreatment liquid, uniform coating due to the wettability to the substrate, and storage stability. Above all, in the case of the pretreatment liquid applied on the base material by the contact method, the total content of the organic solvent is more preferably 0.15 to 30% by weight, more preferably 0.2 to 20% by weight. Is particularly preferable. Further, in the case of the pretreatment liquid applied on the substrate by the non-contact printing method, the total content of the organic solvent is more preferably 1 to 40% by weight, more preferably 2 to 30% by weight. Is particularly preferred.

Further, the pretreatment liquid of the present invention is characterized in that the content of the organic solvent having a boiling point of 180 ° C. or higher is 15% by weight or less based on the total weight of the pretreatment liquid. The term "content is 15% by weight or less" means that the organic solvent having a boiling point of 180 ° C. or higher is not contained, or if it is contained, the content is 15% by weight or less. By keeping the content of the organic solvent at 180 ° C. or higher within the above range, the drying property of the pretreatment liquid is made suitable, and the drying property of the ink to be applied later is not adversely affected. By eliminating the residual organic solvent in the printed matter, it is possible to suppress adhesion to the inside of the coating device and set-off when the base materials are stacked, thereby realizing high-speed printing. Although the detailed factor is unknown, when inkjet printing is performed on the ink agglomerate layer prepared by using the pretreatment liquid satisfying the above conditions, the polyvalent metal ions are instantly dissolved in the ink applied later. , Sufficient bleeding / color unevenness suppressing effect can be exhibited. Among the organic solvents exemplified above, those having a boiling point of 180 ° C. or higher are 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,3. -Butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 2,2- Dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl- 1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, diethylene glycol, triethylene glycol, polyethylene glycol # 200 , Polyethylene glycol # 400, Polyethylene glycol # 600, Dipropylene glycol, Butylene glycol, Divalent alcohols such as dibutylene glycol, Trivalent alcohols such as glycerin, Diethylene glycol monopropyl ether, Diethylene glycol monobutyl ether, Diethylene glycol monopentyl ether, Diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, Glycol monoalkyl ethers such as dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, diethylene glycol butylmethyl ether, triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol butyl methyl ether , Triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol butyl methyl ether, tetraethylene glycol diethyl ether and other glycol dialkyl ethers, and above. Any of the exemplified nitrogen-containing solvent and heterocyclic compound can be mentioned.
Further, from the same viewpoint as above, in addition to the above conditions, the pretreatment liquid of the present invention contains an organic solvent having a boiling point of 240 ° C. or less, which is 10% by weight or less based on the total weight of the pretreatment liquid. It is preferable that it is 5% by weight or less, and it is extremely preferable that it is 5% by weight or less.

Further, in order to ensure high-speed printability and improve image quality on various substrates, the pretreatment liquid of the present invention preferably contains an organic solvent having a low surface tension. As described above, in the present invention, in order to obtain a high-quality printed matter in high-speed printing, it is important that the substrate can be uniformly applied regardless of the liquid absorbency and unevenness, and by using an organic solvent having a small surface tension. It is considered that the wettability of the pretreatment liquid containing the polyvalent metal salt can be dramatically improved. In addition, since the wettability of the pretreatment liquid on the substrate and the image quality of the inkjet ink applied later can be improved, an organic solvent having a low surface tension and the surfactant described below are used in combination. It is particularly preferable to control the surface tension of the treatment liquid.

The organic solvent having a small surface tension in the present embodiment preferably has a surface tension of 20 to 32 mN / m, more preferably 20 to 30 mN / m, and more preferably 20 to 28 mN / m at 25 ° C. Especially preferable. By using the organic solvent having the surface tension, the surface tension of the pretreatment liquid can be kept within a suitable range.

Further, the content of the organic solvent having a small surface tension is preferably 35 to 100% by weight, more preferably 40 to 100% by weight, more preferably 50 to 100% by weight, based on the total amount of the organic solvent in the pretreatment liquid. It is particularly preferable that it is contained in an amount of 100% by weight. By keeping the content of the organic solvent having a small surface tension within the above range, the effect of lowering the surface tension of the organic solvent having a small surface tension can be suitably exhibited.

Among the organic solvents exemplified above, the organic solvents having a surface tension of 20 to 32 mN / m at 25 ° C. include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and 3-methoxy. Monohydric alcohols such as 1-butanol and 3-methoxy-3-methyl-1-butanol,
1,2-Butandiol, 1,2-Pentanediol, 1,2-hexanediol, 1,2-Heptanediol, 2-Methyl-2-propyl-1,3-Propanediol, 2-Methylpentane-2, Dihydric alcohols (glycols) such as 4-diol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, etc.
Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl Ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, Glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether,
Diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol butyl methyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol butyl methyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol. Examples thereof include glycol dialkyl ethers such as methyl ethyl ether, tetraethylene glycol butyl methyl ether and tetraethylene glycol diethyl ether.
Among these compounds, for the above reasons, it is more preferable to select a compound containing at least one hydroxyl group in the molecular structure, more preferably at least alcohols, and at least monohydric alcohols. Most preferred.
The above organic solvent may be used alone or in combination of two or more.

<Binder resin>
The pretreatment liquid of the present invention may further contain a binder resin. The binder resin is a polymer that does not participate in the reaction between the inkjet ink and the pretreatment liquid, and by using the binder resin in combination, the water resistance of the printed matter can be improved and the printed matter can be used for various purposes. Generally, a water-soluble resin and resin fine particles are known as the binder resin, and either of them may be used in the present invention.

The content of the binder resin is defined with respect to the amount of metal ions, and the weight ratio of the content of the binder resin to the content of the metal ions contained in the pretreatment liquid is more than 0 and less than 20. It is preferable that the amount exceeds 0 and is less than 10, and particularly preferably the amount exceeds 0 and is less than 4. In the above range, the water resistance is improved, the coating film cracking does not occur, and the dissolution of the polyvalent metal salt is not hindered as compared with the case where the binder resin is not contained, so that a high-quality printed matter with high image quality can be obtained.

In the present invention, any binder resin can be used. Above all, in the case of the pretreatment liquid applied on the substrate by the contact method, it is stable without thickening or settling in the long term when mixed with the metal salt, and it is instantly miscible with the inkjet ink. It is preferable to select a water-soluble resin as the binder resin from the viewpoints of more effectively exhibiting the coagulation ability of the pretreatment liquid in high-speed printing and excellent drying property until the coating film is formed. Further, among them, it is preferable to use a nonionic water-soluble resin because it is effective in improving water resistance and suppressing cracking, and it does not cause thickening or sedimentation and has good stability as a pretreatment liquid. Further, as long as the basic performance of the pretreatment liquid can be maintained, a resin obtained by adding an anion unit or a cation unit to these nonionic polymers may be used, but a resin substantially free of the unit is used. Is more preferable. The "resin substantially free of anion unit or cation unit" means a resin having an acid value of 0 to 10 mgKOH / g and an amine value of 0 to 10 mgKOH / g. Further, the acid value and the amine value can be measured by, for example, a potential difference automatic titration device described later.

In the present invention, specific examples of the types of binder resins that can be suitably used in the pretreatment liquid applied to the substrate by the contacting method include polyethyleneimine, polyamide, and various quaternary ammonium base-containing water-soluble resins. , Polyacrylic amide, polyvinylpyrrolidone, polyalkylene oxide (however, the weight average molecular weight measured by the following method is 1,000 or more), starch, methylcellulose, hydroxycellulose, carboxymethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, Examples thereof include, but are not limited to, water-soluble cellulose such as hydroxypropylmethyl cellulose, polyvinyl methyl ether, polyvinyl acetal and polyvinyl alcohol, and modified products thereof.
Of these, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetal, and polyalkylene oxide (however, however,) can absorb liquid components in the inkjet ink to be printed later and improve the drying property especially in high-speed printing. It is preferable to select at least one of water-soluble cellulose and modified products thereof (those having a weight average molecular weight of 1,000 or more as measured by the following method).
In particular, polyvinyl alcohol has the physical characteristics necessary for a pretreatment agent for inkjet inks, such as transparency, film strength, and binder power against pigments, is easily available, and has a wide variety of types including modified products. It is particularly preferable in terms of being present.
Furthermore, since the change in pH with time is suppressed, it is most preferable to use polyvinyl alcohol having a saponification degree of 95% or more.
That is, by using polyvinyl alcohol having a saponification degree of 95% or more as the binder resin, an inkjet agglomerated layer having excellent gloss and transparency can be obtained in addition to improving water resistance and suppressing coating film cracking, and over time. A pretreatment liquid having excellent pH stability can be obtained.
Further, in particular, a modified product of polyvinyl alcohol, particularly polyvinyl alcohol modified with a hydrophobic group, is extremely preferably selected because it leads to improvement in storage stability of the liquid and further improvement in water resistance.

When the pretreatment liquid of the present invention is used in a printing method applied on a substrate by a contact method, the number average molecular weight (Mn) of the binder resin is preferably 3,000 to 90,000. , 4,000 to 86,000 is particularly preferable. In the binder resin in the above range, the water resistance generally required is sufficiently exhibited, the ink coating film does not crack due to the swelling of the ink agglomerate layer, and the multivalent metal ions can be sufficiently transferred. It is preferably selected because it does not inhibit the aggregation effect. Further, by using the binder resin in the above number average molecular weight range, the viscosity of the pretreatment liquid can be kept within a suitable range.

The number average molecular weight and the weight average molecular weight in the present invention can be measured by a conventional method. As an example, it is measured as a polystyrene-equivalent number average molecular weight measured by using a TSKgel column (manufactured by Tosoh) and a GPC (manufactured by Tosoh, HLC-8120GPC) equipped with an RI detector using THF as a developing solvent. can do.

On the other hand, even in the case of the pretreatment liquid applied on the substrate by the non-contact printing method, any binder resin can be used. The form may be either a water-soluble resin or resin fine particles, but the water-soluble resin is based on the same reason as in the case of the pretreatment liquid applied to the substrate by the abutting method described above. It is preferable to select.

In the present invention, specific examples of the types of binder resins that can be suitably used in the pretreatment liquid applied to the substrate by the non-contact printing method are acrylic resin, styrene acrylic resin, maleic acid resin, and styrene maleic acid resin. , Urethane resin, olefin resin, vinylpyrrolidone resin (polyvinylpyrrolidone), alkylene oxide resin (however, those having a weight average molecular weight of 1,000 or more) and the like, but needless to say, they are not limited thereto.
Among the resin types listed above, acrylic resin and styrene acrylic resin can be applied uniformly without partially changing the film thickness, and can suppress poor filling and bleeding of printed matter. It is preferable to select at least one selected from styrene maleic acid resin, olefin resin, and vinylpyrrolidone resin.

When the pretreatment liquid of the present invention is used in a printing method applied on a substrate by a non-contact printing method, the weight average molecular weight (Mw) of the binder resin is 1,000 to 50,000. Is preferable, and 3,000 to 45,000 is particularly preferable. The binder resin in the above range can improve the water resistance and abrasion resistance of the printed matter without hindering the movement of the multivalent metal ion in the pretreatment liquid layer, and can improve the discharge stability and storage of the pretreatment liquid. It is also preferred because of its good stability. Further, by using the binder resin in the weight average molecular weight range, the viscosity of the pretreatment liquid can be kept within a suitable range.

<Surfactant>
The pretreatment liquid of the present invention preferably uses a surfactant in order to adjust the surface tension and improve the wettability on the substrate. Various surfactants are known, such as acetylene-based, siloxane-based, acrylic-based, and fluorine-based, depending on the application. In order to achieve both the print stability of the pretreatment liquid and the printing stability of the pretreatment liquid, it is preferable to use a siloxane-based and / or an acetylene-based surfactant, and it is possible to prevent unevenness when the pretreatment liquid is applied. , It is most preferable to use an acetylene-based surfactant.

The surfactant used in the present invention can be synthesized by a known method or a commercially available product can be used. When the surfactant is selected from commercially available products, for example, BY16-201, FZ-77, FZ-2104, FZ-2110, FZ-2162, F-2123, L-7001, L-7002, as siloxane-based surfactants. ＳＦ８４２７、ＳＦ８４２８、ＳＨ３７４９、ＳＨ８４００、８０３２ＡＤＤＩＴＩＶＥ、ＳＨ３７７３Ｍ（東レ・ダウコーニング社製）、Ｔｅｇｏｇｌｉｄｅ４１０、Ｔｅｇｏｇｌｉｄｅ４３２、Ｔｅｇｏｇｌｉｄｅ４３５、Ｔｅｇｏｇｌｉｄｅ４４０、Ｔｅｇｏｇｌｉｄｅ４５０、Ｔｅｇｏｔｗｉｎ４０００、Ｔｅｇｏｔｗｉｎ４１００、Ｔｅｇｏｗｅｔ２５０、Ｔｅｇｏｗｅｔ２６０、Ｔｅｇｏｗｅｔ２７０、Ｔｅｇｏｗｅｔ２８０（エボニックデグサ社製）、ＳＡＧ－ 002, SAG-503A (manufactured by Nissin Chemical Industries, Ltd.), BYK-331, BYK-333, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYKUV3500, BYK-UV3510 (Big Chemie) KF-351A, KF-352A, KF-353, KF-354L, KF355A, KF-615A, KF-640, KF-642, KF-643 (manufactured by Shin-Etsu Chemical Co., Ltd.), etc.
As acetylene-based surfactants, Surfinol 61, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 420, 440, 465, 485, SE, SE-F, Dynol 604, 607 (manufactured by Air Products Co., Ltd.) ), Orfin E1004, E1010, E1020, PD-001, PD-002W, PD-004, PD-005, EXP. 4001, EXP. 4200, EXP. 4123, EXP. 4300 (manufactured by Nissin Chemical Industry Co., Ltd.) and the like can be mentioned.
The above-mentioned surfactant may be used alone or in combination of two or more.

The amount of the surfactant added to the pretreatment liquid of the present invention is preferably 0.01% by weight or more and 5.0% by weight or less, and 0.05% by weight or more and 3.0% by weight with respect to the total amount of the pretreatment liquid. The following are particularly preferred. However, the content of the surfactant needs to be determined in consideration of the surface tension of the inkjet ink described later.

In the present invention, from the viewpoint of preventing bleeding of printed matter, it is preferable that the surface tension of the pretreatment liquid is equal to or higher than the surface tension of the inkjet ink. By making the surface tension of the pretreatment liquid larger than the surface tension of the inkjet ink, the surfactant is used to the extent that it does not hinder the wet spread of the inkjet ink to be printed later when the pretreatment liquid is applied to the substrate. Is preferable because it is appropriately oriented on the surface of the coating film.

Further, in order to make the pretreatment liquid of the present invention compatible with high-speed printing on various substrates, as a surfactant contained in the pretreatment liquid, HLB (Hydrophile-Lipopfile), which is a parameter representing the hydrophilicity and hydrophobicity of the material, is used. It is preferable to use one having a Balance) value of 1 to 8. Since a surfactant having an HLB value of 8 or less has an excellent orientation rate to the surface of the pretreatment liquid, the surfactant moves to the interface between the base material and the pretreatment liquid immediately after being applied to the base material. Then, the wettability of the pretreatment liquid is improved. Further, by keeping the HLB value within 1 to 8, the wettability of the inkjet ink to be applied later can be ensured, and the image quality can be further improved. It is more preferable to use a surfactant having an HLB value of 1.5 to 6.5, and it is particularly preferable to use a surfactant having an HLB value of 2 to 5.

The HLB value of the surfactant can be calculated by using the Griffin method when the structure of the surfactant is clearly known, but when a compound having an unknown structure is contained, for example. "Surfactant Handbook" (edited by Nishiichiro et al., Sangyo Tosho Co., Ltd., 1960), p. The HLB value of the surfactant can be determined experimentally by the method described in 324. Specifically, after dissolving 0.5 g of the surfactant in 5 mL of ethanol, the solution is titrated with a 2 wt% phenol aqueous solution while stirring at 25 ° C., and the end point is where the solution becomes turbid. .. When the amount of the aqueous phenol solution required up to the end point is A (mL), the HLB value can be calculated by the following formula (2).

Equation (2):

HLB value = 0.89 × A + 1.11

<Water>
The content of water contained in the pretreatment liquid of the present invention is preferably in the range of 10 to 90% by weight, more preferably 20 to 85% by weight, and more preferably 30 to 80% by weight with respect to the total amount of the pretreatment liquid. It is more preferably by weight%.

<Other materials>
The pretreatment liquid of the present invention suppresses damage to the members used in the coating apparatus, maximizes the effect of suppressing bleeding as an ink agglomerate layer, and further suppresses pH fluctuation over time and pretreatment. A pH adjuster can be added to the pretreatment liquid for the purpose of maintaining the performance as a liquid for a long period of time. In the present invention, a material having a pH adjusting ability can be arbitrarily selected, and when basicizing, an alkanolamine such as dimethylethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, etc.; ammonia water; water. Hydroxides of alkali metals such as lithium oxide, sodium hydroxide and potassium hydroxide; alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium hydrogen carbonate and potassium carbonate can be used.
For acidification, use hydrochloric acid, sulfuric acid, acetic acid, citric acid, maleic acid, maleic anhydride, succinic acid, tartaric acid, malic acid, phosphoric acid, boric acid, fumaric acid, malonic acid, ascorbic acid, glutamate, etc. be able to.
The above pH adjusters may be used alone or in combination of two or more. In order to strictly control the pH and maximize the desired physical properties, it is preferable to use two or more kinds in combination.

The blending amount of the pH adjuster is preferably 0.01 to 5% by weight, more preferably 0.1 to 4.5% by weight, based on the total amount of the pretreatment liquid. If the amount of the pH adjuster is too small, the pH will change immediately due to external stimuli such as the dissolution of carbon dioxide, while if the pH adjuster is excessively contained, the function of the metal salt in the pretreatment liquid will be impaired. Therefore, it is preferable to keep the blending amount within the above range.

<Other ingredients>
Further, in the pretreatment liquid of the present invention, additives such as an antifoaming agent and an antiseptic can be appropriately added in order to obtain desired physical property values. When these additives are used, the blending amount thereof is preferably 0.01% by weight or more and 10% by weight or less, and preferably 0.01% by weight or more and 5% by weight or less with respect to the total amount of the pretreatment liquid. More preferred. If it is excessively blended, the function of the metal salt in the pretreatment liquid may be impaired. Therefore, the addition amount is preferably in the above range.

<Manufacturing method of pretreatment liquid>
The pretreatment liquid of the present invention composed of the above components is, for example, a metal salt, water, an organic solvent, and, if necessary, a binder resin, a surfactant, a pH adjuster, and appropriately selected as described above. It is manufactured by adding the additive component to be added, stirring and mixing, and then filtering as necessary. The binder resin may be dissolved or dispersed in water or an organic solvent in advance and added in the form of a binder resin dissolution / dispersion liquid. However, the method for producing the pretreatment liquid of the present invention is not limited to the above.

Further, when dissolving the binder resin and / or stirring and mixing the pretreatment liquid, the mixture may be heated in the range of 40 to 100 ° C., if necessary. However, when the resin fine particles are used as the binder resin, it is preferable to heat the resin fine particles at a temperature equal to or lower than the MFT.

Further, when performing filtration, the opening diameter of the filter is not particularly limited as long as it can remove coarse particles and dust, but is preferably 0.3 to 10 μm, more preferably 0.5 to 5 μm. Further, when performing filtration, the filter may be a single type or a plurality of types may be used in combination.

<Characteristics of pretreatment liquid>
The pH of the pretreatment liquid of the present invention is not particularly limited, but if 4 ≦ pH ≦ 9, it is preferable because the aggregation effect of the inorganic metal salt and / or the organometallic salt is high. A particularly preferred pH range is 5-8.

The pH can be measured by a known method, for example, a tabletop pH meter F-72 manufactured by HORIBA, Ltd., using a standard Tou pH electrode or a sleeve Tou pH electrode.

When the pretreatment liquid of the present invention is used in a printing method applied on a substrate by a contact method, it is preferable to adjust the viscosity at 25 ° C. to be higher than 9 mPa · s and 30 mPa · s or less. By keeping the viscosity within the above range, uniform coating can be performed without the pretreatment liquid flowing during drying and the film thickness not partially changing. Any pretreatment liquid that satisfies the above viscosity range can be used for various printing methods described later. Further, regardless of the printing method of the pretreatment liquid, the viscosity of the pretreatment liquid at 25 ° C. is 9.5 or higher from the viewpoint of excellent uniform coatability at high speed and exhibiting excellent functions. It is more preferably 29 mPa · s, and most preferably 10 to 28 mPa · s. On the other hand, when the pretreatment liquid of the present invention is used in a printing method applied on a substrate by a non-contact printing method, the pretreatment liquid has stable ejection characteristics regardless of the structure and type of the inkjet head. From the viewpoint of obtaining the above, it is preferable to adjust the viscosity at 25 ° C. to 3 to 20 mPa · s, more preferably 4 to 10 mPa · s, and further preferably 6 to 10 mPa · s.

The viscosity of the pretreatment liquid in the present invention can be measured using, for example, an E-type viscometer (TVE25L-type viscometer manufactured by Toki Sangyo Co., Ltd.).

The surface tension of the pretreatment liquid of the present invention at 25 ° C. is preferably 20 to 45 mN / m. By keeping the surface tension of the pretreatment liquid within the above range, it is possible to make the instantaneous wettability suitable, and to suppress the occurrence of coating unevenness especially during high-speed printing and realize uniform coating. In addition, the wettability of the ink applied on the top is also improved. That is, even during high-speed printing, the printed matter is filled and the uniform coatability is good, and a high-quality printed matter can be obtained. From the viewpoint of obtaining a pretreatment liquid that can be applied to ultra-high-speed printing close to 100 m / min, the surface tension of the pretreatment liquid at 25 ° C. is more preferably 21 to 43 mN / m, preferably 22 to 42 mN / m. It is particularly preferable that the temperature is 23 to 40 mN / m, and most preferably 23 to 40 mN / m. Further, as described above, it is preferable that the surface tension of the pretreatment liquid is equal to or higher than the surface tension of the inkjet ink because the wettability of the ink applied above is improved and bleeding and color unevenness can be reduced.

The surface tension of the pretreatment liquid in the present invention can be measured by the platinum plate method in an environment of 25 ° C. using, for example, a surface tension meter (CBVPZ manufactured by Kyowa Surface Science Co., Ltd.).

<Applying amount of pretreatment liquid>
When the pretreatment liquid of the present invention is applied to a substrate to obtain a coating film, the coating amount of the pretreatment liquid of the present invention is preferably 1 to 25 g / m ² . By keeping the coating amount within the above range, bleeding and cracking are suppressed, and the dryness of the pretreatment liquid layer after coating becomes good, and adhesion to the inside of the coating equipment and the substrate after printing are layered. It is possible to prevent set-off and obtain printed matter without a feeling of tackiness (stickiness).

The amount of the pretreatment liquid applied to the base material is, for example, determined by the following formula (3) based on the weight increase when the entire surface is coated on a predetermined area in the base material.

Equation (3):

(Applying amount of pretreatment liquid) (g / m ² ) = (AB) × 10000 ÷ C ÷ D

In the formula (3), A represents the weight (g) of the base material after the entire surface of the pretreatment liquid is applied, B represents the weight of only the base material before the coating, and C. Represents the area (cm ² ) of the coated base material, and D represents the specific weight (g / cm ² ) of the pretreatment liquid.

Subsequently, the components of the inkjet ink of the present invention will be described below.

<Pigment>
In addition to having water resistance, light resistance, weather resistance, gas resistance, etc., the inkjet ink of the present invention has a higher aggregation rate than a dye when the pretreatment liquid of the present invention is used in high-speed printing. A pigment is included as a coloring material from the viewpoint of obtaining an image with high image quality. In the present invention, any known organic pigment or inorganic pigment can be used. These pigments are preferably contained in the range of 2% by weight or more and 15% by weight or less, more preferably 2.5% by weight or more and 15% by weight or less with respect to the total amount of the inkjet ink, and 3% by weight. It is particularly preferable that it is contained in the range of% or more and 10% by weight or less. By setting the pigment content to 2% by weight or more, sufficient color development can be obtained even with 1-pass printing. Further, by setting the pigment content to 15% by weight or less, the viscosity of the inkjet ink can be kept within a range suitable for inkjet printing, and the long-term stability of the inkjet ink can be maintained in good condition, resulting in long-term stability. Printing stability can be ensured.

Examples of the cyan organic pigment that can be used in the present invention include C.I. I. Pigment Blue 1, 2, 3, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64, 66 and the like. Among them, C.I. I. Pigment Blue 15: 3 and / or 15: 4 is preferred.

Examples of the magenta organic pigment that can be used in the present invention include C.I. I. Pigment Red 5, 7, 12, 22, 23, 31, 48 (Ca), 48 (Mn), 49, 52, 53, 57 (Ca), 57: 1, 112, 122, 146, 147, 150, 185. , 238, 242, 254, 255, 266, 269, C.I. I. Pigment Bio Red 19, 23, 29, 30, 37, 40, 43, 50 and the like. Among them, C.I. I. Pigment Red 122, 150, 185, 266, 269 and / or C.I. I. One or more selected from the group consisting of Pigment Violet 19 is preferred. Above all, C.I. I. Pigment Bio Red 19 is particularly preferable because it exhibits color reproduction close to that of Japan Color 2011 and FOGRA39, which is a European color standard, and also exhibits particularly high color development when used in combination with the pretreatment liquid of the present invention.

Examples of the yellow organic pigment that can be used in the present invention include C.I. I. Pigment Yellow 10, 11, 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185, 213 and the like can be mentioned. Among them, C.I. I. One or more selected from the group consisting of Pigment Yellow 13, 14, 74, 120, 180, 185, and 213 is preferable.

Examples of the black organic pigment that can be used in the present invention include aniline black, lumogen black, and azomethine azo black. Further, a plurality of chromatic pigments such as the above-mentioned cyan pigment, magenta pigment and yellow pigment, and the following orange pigment, green pigment and brown pigment may be used to obtain a black pigment.

Spot colors such as orange pigment, green pigment, and brown pigment can also be used in the inkjet ink of the present invention. Specifically, C.I. I. Pigment Orange 16, 36, 43, 51, 55, 59, 61, 64, 71, C.I. I. Pigment Green 7, 36, 4
3, 58, Pigment Brown 23, 25, 26 and the like can be mentioned.

The inorganic pigment used in the present invention is not particularly limited, and examples thereof include carbon black and iron oxide as black pigments and titanium oxide as white pigments.

Examples of the carbon black pigment that can be used in the present invention include carbon black produced by the furnace method and the channel method. Among these carbon blacks, the primary particle diameter is 11 to 50 nm, and the specific surface area by the BET method is 50 to 400 m ² / g.
, Those having characteristics such as a volatile content of 0.5 to 10% by weight and a pH of 2 to 10 are suitable. As a commercially available product having such characteristics, for example, No. 25, 30, 33, 40, 44, 45, 52, 850, 900, 950, 960, 970, 980, 1000, 2200B, 2300, 2350, 2600; MA7, MA8, MA77, MA100, MA230 (Mitsubishi Chemical Corporation) , RAVEN760UP, 780UP, 860UP, 900P, 1000P, 1060UP, 1080UP, 1255 (manufactured by Columbian Carbon), REGAL330R, 400R, 660R, MOGUL L (manufactured by Cabot), Nipex160IQ, 170IQ, 35,75; 35, 40, 45, 55, 75, 80, 85, 90, 95, 300; SpecialBlack350, 550; Neurox305, 500, 505, 600, 605 (manufactured by Orion Engineered Carbons), etc., all of which are preferably used. can do.

Further, as titanium oxide preferably used as a white inorganic pigment, either anatase type or rutile type can be used, but it is preferable to use rutile type in order to improve the concealing property of printed matter. Further, it may be produced by any method such as a chlorine method or a sulfuric acid method, but it is preferable to use titanium oxide produced by the chlorine method because the whiteness is high.

The surface of the titanium oxide pigment that can be used in the present invention is preferably treated with an inorganic compound and / or an organic compound. Examples of inorganic compounds include compounds of silicon, aluminum, zirconium, tin, antimony, titanium, and hydrated oxides thereof. Examples of organic compounds include polyhydric alcohols, alkanolamines or derivatives thereof, higher fatty acids or metal salts thereof, organic metal compounds, etc. Among them, polyhydric alcohols or derivatives thereof have a high degree of titanium oxide surface. It can be made hydrophobic and the dispersion stability can be improved, and is preferably used.

In the present invention, in order to keep the hue and color development of the printed matter within a suitable range, a plurality of the above pigments can be mixed and used. For example, in order to improve the tint at a low printing rate, a small amount of one or more pigments selected from cyan organic pigments, magenta organic pigments, orange organic pigments, and brown organic pigments is used for black inks using carbon black pigments. Can be added.

<Pigment dispersion resin>
As a method for stably dispersing and holding the pigment in the inkjet ink, a method of adsorbing and dispersing the pigment dispersion resin on the surface of the pigment, and a method of adsorbing and dispersing a water-soluble and / or water-dispersible surfactant on the surface of the pigment. , A method of chemically and physically introducing a hydrophilic functional group on the surface of the pigment and dispersing it in the ink without a dispersant or a surfactant, a method of coating the pigment with a self-dispersing resin and microencapsulating it, etc. Can be mentioned.

For the inkjet ink used in the present invention, it is preferable to select the method using the pigment dispersion resin among the above. By selecting and examining the monomer composition and molecular weight of the pigment-dispersed resin, the resin adsorption capacity for the pigment and the charge of the pigment-dispersed resin can be easily adjusted. This is because it is possible to control the ability of the liquid to reduce the dispersion function of the pigment.

The type of the pigment dispersion resin used in the present invention is not particularly limited, and for example, acrylic resin, styrene acrylic resin, maleic acid resin, styrene maleic acid resin, urethane resin, ester resin and the like can be used. In the present invention, it is particularly preferable to use an acrylic resin or a styrene acrylic resin in terms of the degree of material selectivity and the ease of synthesis. The pigment dispersion resin used in the present invention can be synthesized by a known method or a commercially available product can be used.

In the present invention, it is preferable to introduce an alkyl group having 10 to 36 carbon atoms into the pigment dispersion resin. This is because by setting the number of carbon atoms of the alkyl group to 10 to 36, it is possible to reduce the viscosity of the pigment dispersion, further stabilize the dispersion, and stabilize the viscosity. The number of carbon atoms of the alkyl group is preferably 12 to 30, and more preferably 18 to 24 carbon atoms. The alkyl group may be linear or branched as long as it has 10 to 36 carbon atoms, but a linear group is preferable. The linear alkyl group includes a lauryl group (C12), a myristyl group (C14), a cetyl group (C16), a stearyl group (C18), an araquil group (C20), a behenyl group (C22), a lignoceryl group (C24), and a cellotoyl group. Examples thereof include a group (C26), a montanyl group (C28), a melissyl group (C30), a dotria-contanoyl group (C32), a tetratria-contanoyl group (C34), a hexatria-contanoyl group (C36) and the like.

The content contained in the copolymer of the monomer containing an alkyl chain having 10 to 36 carbon atoms contained in the pigment dispersion resin used in the present invention is to reduce the viscosity of the pigment dispersion and the abrasion resistance of the printed matter. From the viewpoint of achieving both good and glossy properties, it is preferably 5% by weight to 60% by weight, more preferably 10% by weight to 55% by weight, and particularly preferably 20% by weight to 50% by weight.

Further, in the present invention, it is particularly preferable to introduce an aromatic group into the pigment dispersion resin because the adsorption ability to the pigment can be improved and the dispersion function of the pigment can be rapidly lowered when mixed with the pretreatment liquid. .. This is a strong molecule called cation-π interaction between the cation component in the metal salt contained in the pretreatment liquid and the pigment dispersion resin having an aromatic group when the pretreatment liquid and the inkjet ink are mixed. This is because the intermolecular force works and both are preferentially adsorbed. Examples of the aromatic group include a phenyl group, a naphthyl group, an anthryl group, a tolyl group, a xsilyl group, a mesitylene group, an anisyl group and the like. Of these, phenyl groups and tolyl groups are preferable from the viewpoint of ensuring sufficient dispersion stability.

From the viewpoint of achieving both the dispersion stability of the pigment and the adsorption performance with the pretreatment liquid, the content of the monomer containing an aromatic ring is preferably 5 to 65% by weight based on the total amount of the pigment dispersion resin. More preferably, it is 10 to 50% by weight.

In the present invention, the acid value of the pigment-dispersed resin is preferably 30 to 400 mgKOH / g. It is preferable to keep the acid value within the above range because the solubility of the pigment dispersion resin in water can be ensured and the viscosity of the pigment dispersion can be suppressed. When the acid value of the pigment dispersion resin is smaller than 30 mgKOH / g, the solubility in water is too low to get wet with the pigment, the pigment dispersion becomes unstable, and when combined with the pretreatment liquid, the pigment dispersion becomes unstable. In addition, it is difficult to cause anion-cation interaction and adsorption equilibrium transfer, and the effect of suppressing color mixing between pigments is reduced. On the contrary, when the acid value of the pigment-dispersed resin is larger than 400 mgKOH / g, the interaction between the pigment-dispersed resins is strengthened, which increases the viscosity and the effect of the pretreatment liquid is insufficient, which is preferable. not. The acid value of the pigment dispersion resin is preferably 50 to 350 mgKOH / g, and more preferably 100 to 300 mgKOH / g.

The acid value can be measured by a potentiometric titration method using a known device, for example, "potentiometric titration device AT-610" manufactured by Kyoto Electronics Manufacturing Co., Ltd.

In the present invention, it is preferable that the acid group is neutralized with a base in order to increase the solubility in the ink. However, if an excessive amount of base is added, the cationic component contained in the pretreatment liquid is neutralized and a sufficient effect cannot be exhibited. Therefore, it is necessary to pay attention to the amount of the base added. Whether or not the amount of the base added is excessive can be confirmed, for example, by preparing a 10% by weight aqueous solution of the pigment-dispersed resin and measuring the pH of the aqueous solution. In the present invention, the pH of the aqueous solution is preferably 7 to 11, more preferably 7.5 to 10.5, in order to fully exhibit the function of the pretreatment liquid.

Examples of the base for neutralizing the pigment dispersion resin used in the present invention include alkanolamines such as diethanolamine, triethanolamine and N-methyldiethanolamine; aqueous ammonia; lithium hydroxide, sodium hydroxide, potassium hydroxide and the like. Hydroxides of alkali metals; carbonates of alkali metals such as lithium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate and the like can be mentioned.

Regarding the molecular weight of the pigment dispersion resin, the weight average molecular weight is preferably in the range of 1,000 or more and 100,000 or less, and more preferably in the range of 5,000 or more and 50,000 or less. When the molecular weight is in the above range, the pigment is stably dispersed in water, and it is easy to adjust the viscosity when applied to a water-based ink. When the weight average molecular weight is 1,000 or less, the dispersed resin is easily dissolved in the solvent added to the ink, and the resin adsorbed on the pigment is desorbed, so that the dispersion stability is significantly deteriorated. It ends up. When the weight average molecular weight is 100,000 or more, the viscosity at the time of dispersion becomes high and the ejection stability from the inkjet head is remarkably deteriorated, so that the printing stability is deteriorated.

The content of the pigment-dispersed resin of the present invention is preferably 1 to 50% by weight with respect to the pigment. By setting the content of the pigment dispersion resin to 1 to 50% by weight with respect to the pigment, the viscosity of the pigment dispersion is suppressed, the viscosity stability and dispersion stability of the pigment dispersion and the inkjet ink are improved, and at the same time. It is preferable because it can cause a rapid deterioration of the dispersion function when mixed with the pretreatment liquid. The content of the pigment dispersion resin is more preferably 2 to 45% by weight with respect to the pigment, still more preferably 4 to 40% by weight with respect to the pigment, and most preferably 5 to 35% by weight with respect to the pigment.

<Water-soluble organic solvent>
As the water-soluble organic solvent used in the inkjet ink of the present invention, any known one can be used, but a glycol ether solvent and / or an alkyl polyol having a boiling point of 180 ° C. or higher and 280 ° C. or lower at 1 atm. It is preferable to contain two or more kinds of based solvents. The boiling point under 1 atm is preferably in the range of 183 ° C or higher and 270 ° C or lower, and more preferably in the range of 185 ° C or higher and 250 ° C or lower. By using a water-soluble organic solvent that satisfies the above boiling point range, the wettability and drying property of the inkjet ink can be controlled in a suitable range, the ejection stability is improved, and the ink jet ink is combined with the pretreatment liquid. At that time, it is possible to prevent image quality defects such as bleeding.

The boiling point under 1 atm in the present invention can be measured by using a thermal analyzer such as DSC (Differential Scanning Calorimetry).

Examples of glycol ether-based solvents having a boiling point of 180 ° C. or higher and 280 ° C. or lower, which are preferably used in the present invention, are diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, and diethylene glycol mono. Hexil Ether, Triethylene Glycol Monomethyl Ether, Triethylene Glycol Monoethyl Ether, Triethylene Glycol Monopropyl Ether, Triethylene Glycol Monobutyl Ether, Tetraethylene Glycol Monomethyl Ether, Tetraethylene Glycol Monoethyl Ether, Tetraethylene Glycol Monobutyl Ether, Dipropylene Glycol monoalkyl ethers such as glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether; diethylene glycol diethyl ether, diethylene glycol isopropylmethyl With glycol dialkyl ethers such as ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol diethyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol methyl ethyl ether, etc. Become.

In the present invention, among the above glycol ether-based solvents, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, and tri Ethylene Glycol Monopropyl Ether, Triethylene Glycol Monobutyl Ether, Dipropylene Glycol Monomethyl Ether, Dipropylene Glycol Monoethyl Ether, Dipropylene Glycol Monopropyl Ether, Dipropylene Glycol Monobutyl Ether, Diethylene Glycolbutyl Methyl Ether, Triethylene Glycol Methyl Ethyl Ether, It is preferable to select triethylene glycol diethyl ether, triethylene glycol butyl methyl ether, or tetraethylene glycol methyl ethyl ether.

Examples of the alkyl polyol solvent having a boiling point of 180 ° C. or higher and 280 ° C. or lower under 1 atm include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, and 1,2-butanediol. , 1,3-Butanediol, 1,4-Butanediol, 1,2-Pentanediol, 1,5-Pentanediol, 1,2-Hexanediol, 1,6-Hexanediol, 1,2-Heptanediol, 2,2-Dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-Methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methylpentane-2,4-diol, 2-ethyl-1,3-hexanediol, diethylene glycol, Examples thereof include dipropylene glycol and dibutylene glycol.

In the present invention, among the above-mentioned alkyl polyol solvents, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,3, butanediol, 1, It is preferable to select 2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, and 1,2-heptanediol.

The total amount of the glycol ether solvent and / or the alkyl polyol solvent used in the present invention having a boiling point of 180 ° C. or higher and 280 ° C. or lower under 1 atm is 5% by weight or more and 50% by weight or less based on the total amount of the inkjet ink. It is preferable to have. Further, from the viewpoint of ensuring ejection stability from the inkjet nozzle and sufficient wettability and drying property when combined with the pretreatment liquid, the total amount of the water-soluble organic solvent is 10% by weight or more and 45% by weight. It is more preferable, and it is particularly preferable that it is 15% by weight or more and 40% by weight or less. If the total amount of the water-soluble organic solvent is less than 5% by weight, the moisturizing property of the ink is insufficient and the ejection stability may be impaired. On the contrary, when the total content of the water-soluble organic solvent is more than 65% by weight, the viscosity of the ink becomes too high, which may impair the ejection stability, which is not preferable.

In the present invention, in order to adjust the moisturizing property and wettability of the inkjet ink, an organic solvent other than the glycol ether solvent and / or the alkyl polyol solvent having a boiling point of 180 ° C. or higher and 280 ° C. or lower under 1 atm is also used. Can be used together. Specifically, as the water-soluble organic solvent that can be used in the pretreatment liquid, the monohydric alcohols, trihydric alcohols, nitrogen-containing solvents, heterocyclic compounds and the like mentioned above can be used. Further, these solvents may be used alone or in combination of two or more.

The total amount of the water-soluble organic solvent in the inkjet ink of the present invention is preferably 5% by weight or more and 70% by weight or less with respect to the total amount of the inkjet ink from the viewpoint of achieving both moisturizing property, drying property and wettability of the inkjet ink. It is more preferably 10% by weight or more and 60% by weight or less, and particularly preferably 15% by weight or more and 50% by weight or less.

Further, in the present invention, as the water-soluble organic solvent contained in the inkjet ink, a water-soluble organic solvent having a boiling point of 240 ° C. or higher at 1 atm is contained in an amount of 0% by weight or more and less than 10% by weight based on the total amount of the water-based inkjet ink. And / or a water-soluble organic solvent having a boiling point of 210 ° C. or higher at 1 atm is preferably contained in an amount of 0% by weight or more and less than 20% by weight based on the total amount of the water-based inkjet ink. By controlling the amount of the organic solvent within the above range, the drying property can be sufficiently improved to the extent that there is no set-off even in high-speed printing.
Further, from the viewpoint that an image having excellent image quality can be obtained even at a high printing speed when combined with the pretreatment liquid, the content of the water-soluble organic solvent having a boiling point of 240 ° C. or higher under 1 atm is set. It is more preferable to contain 0% by weight or more and less than 7% by weight, and particularly preferably 0% by weight or more and less than 5% by weight, based on the total amount of the water-based inkjet ink.
For the same reason, the content of the water-soluble organic solvent having a boiling point of 210 ° C. or higher under 1 atm is more preferably 0% by weight or more and less than 18% by weight, more preferably 0% by weight, based on the total amount of the water-based inkjet ink. It is particularly preferable that the content is more than 16% by weight.
In the above, "containing 0% by weight" means that the water-soluble organic solvent satisfying the conditions is not contained.

<Binder resin>
It is preferable to add a binder resin to the inkjet ink of the present invention. As described above, as the binder resin, a water-soluble resin and resin fine particles are generally known. Of these, the resin fine particles have a higher molecular weight than the water-soluble resin, and the resin fine particles can lower the viscosity of the inkjet ink, and a larger amount of resin can be blended in the inkjet ink. Suitable for increasing resistance. Examples of the type of resin used as the resin fine particles include acrylic resin, styrene acrylic resin, urethane resin, styrene butadiene resin, vinyl chloride resin, and olefin resin. Among them, acrylic resin and styrene acrylic resin resin fine particles are preferably used in consideration of ink stability and printed matter resistance.

However, when the binder resin in the inkjet ink is resin fine particles, it is necessary to consider the minimum film forming temperature (MFT) of the resin fine particles. When resin fine particles with low MFT are used, the MFT of the resin fine particles is further lowered by the water-soluble organic solvent added to the inkjet ink, and the resin fine particles are fused or aggregated even at room temperature. As a result, the inkjet head nozzle This is because clogging may occur. In order to avoid the above problem, it is preferable to adjust the monomer constituting the resin fine particles so that the MFT of the resin fine particles is 60 ° C. or higher.

The MFT can be measured by, for example, an MFT tester manufactured by Tester Sangyo Co., Ltd. Specifically, after applying a 25% by weight aqueous solution of resin fine particles on the film so that the WET film thickness is 300 μm, the film is allowed to stand on the tester with a temperature gradient applied, and white precipitates are formed after drying. The temperature at the boundary between the generated region and the region where the transparent resin film is formed is defined as MFT.

However, considering the maintenance performance of the inkjet printer, it is more preferable that the binder resin is a water-soluble resin in the present invention. The water-soluble resin preferably has a weight average molecular weight in the range of 8,000 or more and 50,000 or less, and more preferably 10,000 or more and 40,000 or less. By setting the weight average molecular weight to 10,000 or more, the coating film resistance of the printed matter can be improved, and by setting the weight average molecular weight to 50,000 or less, the ejection stability from the inkjet head is excellent. Inkjet ink can be obtained.

The acid value is also important when selecting a water-soluble resin as the binder resin, and the acid value is preferably 10 to 80 mgKOH / g, and more preferably 20 to 50 mgKOH / g. If the acid value is less than 10 mgKOH / g, the resolubility of the solidified inkjet ink is poor, and clogging occurs on the inkjet head nozzle as in the case of resin fine particles, resulting in a significant decrease in printing stability. When combined, it is difficult to cause thickening / aggregation of the ink due to the interaction between anion and cation, and the effect of suppressing bleeding and color unevenness is reduced, which is not preferable. Further, when the acid value is 80 mgKOH / g or more, it is possible to dissolve the inkjet ink again even if it solidifies, but it is not preferable because the water resistance of the printed matter coating film is remarkably deteriorated.

The content of the binder resin in the total amount of the inkjet ink is in the range of 1% by weight or more and 20% by weight or less, and more preferably 2% by weight or more and 15% by weight or less in terms of solid content. Particularly preferably, it is in the range of 3% by weight or more and 10% by weight or less.

<Surfactant>
The inkjet ink of the present invention preferably uses a surfactant for the purpose of adjusting the surface tension and improving the image quality. On the other hand, if the surface tension is too low, the nozzle surface of the inkjet head gets wet with the inkjet ink and the ejection stability is impaired. Therefore, it is very important to select the type and amount of the surfactant. From the viewpoint of ensuring optimum wettability and realizing stable ejection from the inkjet nozzle, it is preferable to use a siloxane-based, acetylene-based, or fluorine-based surfactant, and a siloxane-based or acetylene-based surfactant is used. It is particularly preferable to do so. The amount of the surfactant added is preferably 0.01% by weight or more and 5.0% by weight or less, more preferably 0.05% by weight or more and 3.0% by weight or less, based on the total amount of the inkjet ink.

In addition, the molecular weight of the surfactant is also important in terms of controlling the wettability in the process of evaporating the inkjet ink and improving the quality of printed matter such as abrasion resistance and solvent resistance. The molecular weight of the surfactant is preferably 1,000 or more and 7,000 or less, and more preferably 1,500 or more and 5,000 or less in terms of weight average molecular weight. When the value is 1,000 or more, the effect of controlling wetting on the printing substrate can be enhanced, and when the value is 7,000 or less, an inkjet ink having excellent storage stability can be obtained.

The surfactant used in the present invention can be synthesized by a known method or a commercially available product can be used. When selecting a surfactant from commercially available products, for example, as a siloxane-based surfactant or an acetylene-based surfactant, those listed above as surfactants that can be used in the pretreatment liquid, and as a fluorine-based surfactant. , ZonylTBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, Capstone FS-
30, FS-31 (DuPont), PF-151N, PF-154N (manufactured by Omniova) and the like can be mentioned. The above-mentioned surfactant may be used alone or in combination of two or more. However, when ink is applied on the pretreatment liquid layer, high-concentration polyvalent metal ions are mixed into the ink layer, which may cause the surface tension of the ink to fluctuate significantly and cause color bleeding. Therefore, it is preferable to use two or more kinds of surfactants in combination in order to suppress fluctuations in the surface tension of the ink.

The surfactant used in the inkjet ink and the surfactant used in the pretreatment liquid may be the same or different. When using different surfactants, it is better to determine the blending amount after paying attention to the surface tensions of both, as described above.

<Water>
As the water contained in the inkjet ink of the present invention, it is preferable to use ion-exchanged water (deionized water) instead of general water containing various ions.

The water content that can be used in the present invention is preferably in the range of 20 to 90% by weight of the total weight of the ink.

<Other ingredients>
In the inkjet ink of the present invention, in addition to the above-mentioned components, a pH adjuster can be added, if necessary, in order to obtain an ink having a desired physical characteristic value. In the present invention, a material having a pH adjusting ability can be arbitrarily selected. For basicization, alkanolamines such as dimethylethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine; aqueous ammonia; hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide; carbonic acid. Alkali metal carbonates such as lithium, sodium carbonate, sodium hydrogen carbonate, and potassium carbonate can be used. For acidification, use hydrochloric acid, sulfuric acid, acetic acid, citric acid, maleic acid, maleic anhydride, succinic acid, tartaric acid, malic acid, phosphoric acid, boric acid, fumaric acid, malonic acid, ascorbic acid, glutamate, etc. be able to. The above pH adjusters may be used alone or in combination of two or more.

The blending amount of the pH adjuster is preferably 0.01 to 5% by weight, more preferably 0.1 to 3% by weight, and 0.2 to 1.5% by weight with respect to the total amount of the inkjet ink. Most preferably. By keeping it within the above range, the pH does not change due to the dissolution of carbon dioxide in the air, and when the pretreatment liquid comes into contact with the ink, the solid component aggregation effect of the polyvalent metal ion is inhibited. It is preferable because the effect of the present invention can be suitably exhibited without any problem.

In addition to the above components, the inkjet ink of the present invention contains additives such as defoaming agents, preservatives, infrared absorbers, and ultraviolet absorbers in order to obtain inks having desired physical properties as needed. It can be added as appropriate. As an example of the addition amount of these additives, 0.01% by weight or more and 10% by weight or less is preferable with respect to the total weight of the ink.

It is preferable that the inkjet ink of the present invention does not substantially contain the polymerizable monomer. Here, "substantially not contained" means that the ink is not intentionally added, and does not exclude a small amount of contamination or generation during manufacturing and storage of the inkjet ink. Specifically, the blending amount of the polymerizable monomer is preferably 3% by weight or less, more preferably 1% by weight or less, and particularly preferably 0.5% by weight or less in the total amount of the inkjet ink. preferable. In the present specification, the "polymerizable monomer" refers to a compound having a polymerizable unsaturated double bond, and examples thereof include an acrylate monomer, a methacrylate monomer, an acrylamide monomer, and a styrene monomer.

<Inkjet ink set>
The inkjet ink of the present invention may be used in a single color, but it can also be used as an inkjet ink set in which a plurality of colors are combined according to the intended use. The combination is not particularly limited, but a full-color image can be obtained by using three colors of cyan, yellow, and magenta. In addition, by adding black ink, it is possible to improve the blackness and improve the visibility of characters and the like. It is also possible to improve the color reproducibility by adding colors such as orange and green. When printing on a printing medium other than white, a clear image can be obtained by using white ink together. When the water-based inkjet ink has magenta ink, the magenta ink is used as the magenta pigment in C.I. I. It is particularly preferred to have Pigment Bio Red 19.

<Manufacturing method of inkjet ink>
The inkjet ink of the present invention composed of the above-mentioned components is produced, for example, through the following process. However, the method for producing the inkjet ink of the present invention is not limited to the following.

(1) Production of Pigment Dispersion First, a pigment is added to an aqueous medium in which a pigment dispersion resin and water are mixed, and the mixture is stirred and then dispersed using a disperser. Then, if necessary, centrifugation or filtration is performed to obtain a pigment dispersion.

It is effective to perform premixing before the distributed processing. Premixing may be performed by adding the pigment to an aqueous medium in which at least the pigment dispersion resin and water are mixed. Such a premixing operation is preferable because it can improve the wettability of the pigment surface and promote the adsorption of the dispersant on the pigment surface.

The disperser used in the dispersion treatment of the pigment may be any generally used disperser, and examples thereof include a ball mill, a roll mill, a sand mill, a bead mill and a nanomizer. Among the above, bead mills are preferably used, and specifically, they are commercially available under trade names such as super mills, sand grinders, agitator mills, grain mills, dyno mills, pearl mills and cobol mills.

In the pigment premixing and dispersion treatment, the pigment dispersant may be dispersed only in water or in a mixed solvent of an organic solvent and water.

As a method of controlling the particle size distribution of the pigment dispersion, the size of the crushed media of the above-mentioned disperser is reduced, the material of the crushed media is changed, the filling rate of the crushed media is increased, and the stirring member ( The shape of the agitator) can be changed, the dispersion treatment time can be lengthened, the classification can be performed with a filter or a centrifuge after the dispersion treatment, and a combination of these methods can be mentioned. In the present invention, in order to keep the pigment in a suitable particle size range, the diameter of the pulverized media of the disperser is preferably 0.1 to 3 mm. Further, as the material of the pulverized media, glass, zircon, zirconia and titania are preferably used.

(2) Preparation of inkjet ink Next, a water-soluble organic solvent, water, and if necessary, a binder resin, a surfactant and other additives mentioned above are added to the pigment dispersion, and the mixture is stirred and mixed.

If necessary, the mixture may be stirred and mixed while heating in the range of 40 to 100 ° C. However, when the resin fine particles are used as the binder resin, the heating temperature is preferably set to be equal to or lower than the MFT of the resin fine particles.

(3) Removal of coarse particles The coarse particles contained in the above mixture are removed by a method such as filtration separation or centrifugation to obtain an inkjet ink. As a method for filtration and separation, a known method can be appropriately used. The opening diameter of the filter is not particularly limited as long as it can remove coarse particles and dust, but is preferably 0.3 to 5 μm, more preferably 0.5 to 3 μm. Further, when performing filtration, the filter may be a single type or a plurality of types may be used in combination.

<Characteristics of inkjet ink>
The inkjet ink of the present invention preferably has a viscosity at 25 ° C. of 3 to 20 mPa · s. In this viscosity region, stable ejection characteristics are exhibited even in a head having a normal frequency of 4 to 10 KHz to a head having a high frequency of 10 to 70 KHz. In particular, by setting the viscosity at 25 ° C. to 4 to 10 mPa · s, stable ejection can be achieved even when used for an inkjet head having a design resolution of 600 dpi or more.

The viscosity of the inkjet ink in the present invention at 25 ° C. can be measured by a conventional method. Specifically, an E-type viscometer (TVE25L-type viscometer manufactured by Toki Sangyo Co., Ltd.) can be used for measurement using 1 mL of ink.

In the inkjet ink of the present invention, the average secondary particle diameter (D50) of the pigment is preferably 40 nm to 500 nm, more preferably 50 nm to 400 nm, and particularly preferably, in order to obtain a printed matter having excellent color development. Is 60 nm to 300 nm. In order to keep the average secondary particle size within the above-mentioned suitable range, the pigment dispersion treatment step may be controlled as described above.

<Manufacturing method of printed matter>
As a method for producing a printed matter using an ink set composed of the pretreatment liquid and the inkjet ink of the present invention, the pretreatment liquid is applied onto a substrate conveyed at a speed of 30 m / min or more, and then the pretreatment liquid is applied. A method of applying inkjet ink to the applied portion by a one-pass printing method is preferably used.

The "one-pass printing method" is a printing method in which the inkjet head is scanned once against a stopped substrate, or the substrate is passed through the lower part of a fixed inkjet head only once, and the printed ink is printed. Ink is not printed again on the top. The 1-pass printing method has a smaller number of scans than the conventional inkjet printing method (multi-pass printing method) in which the inkjet head is scanned multiple times, and the printing speed can be increased. Therefore, it is suitable for industrial applications where printing speed is required. It is considered suitable. In particular, it can be said that the adoption of this method is indispensable for realizing inkjet printing as an alternative to offset printing and gravure printing, which has been actively studied in recent years.

On the other hand, in order to replace inkjet printing with offset printing and gravure printing, various problems must be solved. Regarding the printing speed, it is necessary to support high-speed printing of at least 30 m / min or more in order to replace the conventional printing method. Needless to say, there are no image defects such as bleeding and color unevenness in the printed matter, but it is essential to obtain a high-quality image at a high recording resolution of 600 dpi or more. The "recording resolution" is expressed in units of dpi (DotsPerInch), and represents the number of inkjet ink droplets applied per inch. The "recording resolution" in the present specification refers to the recording resolution in the transport direction of the base material and the direction perpendicular to the transport direction in the base material surface (
Hereinafter, it refers to both recording resolutions in the recording width direction).

As described above, in order to realize high-speed printing in inkjet printing, it is essential to adopt a one-pass printing method. On the other hand, in order to complete printing in one scan, the amount of ink droplets (drop volume) ejected from the inkjet head nozzle at one time is larger than that in the case of printing the same image by the multi-pass printing method. As explained in the prior art, in the case of an inkjet ink that contains water as a constituent component and fixes the image by penetrating into the substrate and / or evaporating the liquid component, an increase in drop volume causes strike-through and drying defects of the inkjet ink. In addition, it was extremely difficult to obtain high-quality images regardless of the base material because the permeability of the inkjet ink differs depending on the base material.

In the present invention, the inorganic metal salt and / or the organic metal salt in the dissolved state described above is contained, and the metal ion derived from the inorganic metal salt and / or the organic metal salt contains a polyvalent metal ion, and The content of the polyvalent metal ion is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid, and contains an organic solvent containing a compound containing one or more hydroxyl groups in the molecular structure, and The above-mentioned problems are solved by using a pretreatment liquid having an organic solvent having a boiling point of 180 ° C. or higher and a content of 15% by weight or less based on the total amount of the pretreatment liquid. That is, the pretreatment liquid is applied onto the base material before printing the inkjet ink, and the ink agglomerate layer is formed on the base material, thereby eliminating the influence of the difference in the base material type. Further, by using the inkjet ink of the present invention, rapid aggregation of solid components and drying of liquid components can be realized, and high-quality images can be obtained in high-speed and high-recording-resolution inkjet printing regardless of the substrate. Is possible.

Hereinafter, a method for manufacturing a printed matter using the ink set of the present invention will be described.

<Method of applying pretreatment liquid>
In the present invention, before printing the inkjet ink, the pretreatment liquid is applied onto the substrate conveyed at a speed of 30 m / min or more. As a method of applying the pretreatment liquid to the base material, either a method of printing in a non-contact manner with the base material such as inkjet printing or a method of printing with the pretreatment liquid in contact with the base material is adopted. You may.

In recent years, an inkjet head capable of ejecting even a liquid composition having a viscosity at 25 ° C. of about 100 mPa · s has been developed by adopting a heater in the head and optimizing the flow path in the head and the nozzle structure. The suitable viscosity range of the pretreatment liquid of the present invention at 25 ° C. is 2 to 100 mPa · s, and the pretreatment liquid can be printed without any problem even in inkjet printing. When inkjet printing is adopted as the method for applying the pretreatment liquid, the pretreatment liquid may be applied only to the portion to which the inkjet ink is applied from the viewpoint that the texture peculiar to the substrate can be left in the non-printed portion. preferable.

On the other hand, from the viewpoint of preventing damage to the members constituting the inkjet head and ensuring the suitability for inkjet printing, the printing method in which the pretreatment liquid is brought into contact with the substrate is preferably used in the present invention. As a printing method for abutting the pretreatment liquid, a conventionally known printing method can be arbitrarily selected, but from the viewpoint of device simplicity, uniform coatability, work efficiency, economy, etc., the roller type is used. It is preferable to adopt it. The "roller type" refers to a printing type in which a pretreatment liquid is previously applied to a rotating roll and then the pretreatment liquid is transferred to a substrate. Examples of the roller type coating machine preferably used in the present invention include an offset gravure coater, a gravure coater, a doctor coater, a bar coater, a blade coater, a flexo coater, and a roll coater.

<Thermal energy action after applying the pretreatment liquid>
In the present invention, it is preferable to apply thermal energy to the base material after applying the pretreatment liquid to the base material and then apply thermal energy to the base material to dry the pretreatment liquid on the base material. Further, it is particularly preferable that the pretreatment liquid is completely dried before the inkjet ink is applied, that is, the liquid component of the pretreatment liquid is completely removed. If the inkjet ink is applied before the pretreatment liquid is completely dried, the dissolution and / or the deterioration of the dispersion function of the solid component in the inkjet ink can be further promoted, while the liquid component on the substrate becomes excessive. If the thermal energy applied after inkjet printing is insufficient, image defects such as waviness and bleeding of the substrate may occur.

The method of action of heat energy used in the present invention is not particularly limited, and examples thereof include a heat drying method, a hot air drying method, an infrared drying method, a microwave drying method, and a drum drying method. The above drying method may be used alone or in combination of two or more. For example, by using the heat drying method and the hot air drying method in combination, the pretreatment liquid can be dried more quickly than when each of them is used alone.

In the present invention, from the viewpoint of preventing damage to the substrate and bumping of the liquid component in the pretreatment liquid, when the heat drying method is adopted among the above, the drying temperature is set to 35 to 100 ° C., and hot air is also used. When the drying method is adopted, the hot air temperature is preferably 50 to 250 ° C. From the same viewpoint, when the infrared drying method is adopted, it is preferable that 50% or more of the integrated value of the total output of infrared rays used for infrared irradiation is present in the wavelength region of 700 nm or more and 1500 nm or less.

<Pretreatment liquid application / drying device>
The pretreatment liquid applying / drying apparatus of the present invention is equipped in-line or offline with respect to the inkjet printing apparatus described later, but it is preferably equipped in-line from the viewpoint of convenience during printing.

<Inkjet ink application method>
As described above, the inkjet ink is applied to the substrate by a one-pass printing method. As described above, there are two types of 1-pass printing methods: a method in which the inkjet head is scanned once against a stopped substrate, and a method in which the substrate is passed through the lower part of the fixed inkjet head only once. However, when scanning the inkjet head, it is necessary to adjust the ejection timing in consideration of the movement of the inkjet head, and the landing position is likely to shift. Therefore, in the present invention, the inkjet head is fixed and the base material is used. The method of scanning is preferably used. At that time, the transport speed of the base material is preferably 30 m / min or more. In particular, when the pretreatment liquid applying device is installed in-line with the inkjet printing device, the pretreatment liquid applying device to the inkjet printing device are continuously arranged, and the base material to which the pretreatment liquid is applied remains as it is. It is preferable that the product is transported to the inkjet printing unit.

Further, as described above, by using the ink set of the present invention, it is possible to produce a high-quality image even at a high speed and a recording resolution of 600 dpi or more, but the image quality is equivalent to that of offset printing or gravure printing. It is particularly preferable that the recording resolution of the printed matter is 1200 dpi or more from the viewpoint that the printed matter having the above can be provided.

<Inkjet head>
When a method of passing the substrate only once under the fixed inkjet head is adopted as the one-pass printing method, the recording resolution in the recording width direction is determined by the design resolution of the inkjet head. As described above, in the present invention, the recording resolution in the recording width direction is preferably 600 dpi or more, and therefore, inevitably, the design resolution of the inkjet head is also preferably 600 dpi or more. If the design resolution of the inkjet head is 600 dpi or more, printing can be performed with one inkjet head for each color, which is preferable from the viewpoint of miniaturization of the apparatus and economy. When using an inkjet head with a design resolution lower than 600 dpi, by using a plurality of inkjet heads for each color side by side in the transport direction of the base material, the recording resolution in the recording width direction can be obtained even in one-pass printing. It is possible to realize 600 dpi or more.

Further, the printing resolution in the transport direction of the substrate depends not only on the design resolution of the inkjet head but also on the driving frequency and printing speed of the inkjet head, for example, the printing speed is halved or the driving frequency is doubled. By setting this, the recording resolution in the transport direction is doubled. If the printing speed of 30 m / min or more cannot achieve a printing resolution of 600 dpi or more in the transport direction due to the design of the inkjet head, printing can be performed by using multiple inkjet heads for each color side by side in the transport direction of the substrate. Both speed and print resolution can be achieved at the same time.

The drop volume of the inkjet ink in the inkjet 1-pass printing of the present invention largely depends on the performance of the inkjet head, but is preferably in the range of 1 to 30 pL in order to realize a high-quality image. Further, in order to obtain a high quality image, it is particularly preferable to use an inkjet head having gradation specifications capable of changing the drop volume.

<Thermal energy action after applying inkjet ink>
In order to dry the inkjet ink and the undried pretreatment liquid after applying the inkjet ink onto the base material to which the pretreatment liquid has been applied, it is preferable to apply thermal energy to the base material. The method and conditions of action of heat energy preferably used in the present invention are the same as those used for drying the above-mentioned pretreatment liquid.

<Inkjet ink dryer>
The inkjet ink drying device is installed in-line or offline with respect to the inkjet printing device, but it is preferable to equip the inkjet ink drying device in-line from the viewpoint of convenience at the time of printing. Further, in the present invention, in order to prevent bleeding, color unevenness, curling of the base material, etc., the thermal energy is preferably applied within 30 seconds after printing, more preferably within 20 seconds, and within 10 seconds. It is particularly preferable to give it.

<Amount of pretreatment liquid and inkjet ink applied>
In the present invention, the ratio of the amount of the inkjet ink applied to the amount of the pretreatment liquid applied is preferably 0.1 or more and 10 or less. The ratio of the applied amount is more preferably 0.5 or more and 9 or less, and particularly preferably 1 or more and 8 or less. By keeping the ratio of the applied amount within the above range, the change in the texture of the base material caused by the excessive amount of the pretreatment liquid and the insufficient effect of the pretreatment liquid due to the excessive amount of inkjet ink occur. High-quality printed matter can be obtained without bleeding or color unevenness.

<Printing speed>
As described above, when a printed matter is produced using the ink set of the present invention, the printing speed is preferably 30 m / min or more, more preferably 50 m / min or more, and 75 m / min or more. It is more preferable, and it is particularly preferable that it is 100 m / min or more.

<Base material>
When printing using the ink set of the present invention, any known base material can be used, for example, high-quality paper, recycled paper, coated paper, art paper, cast paper, finely coated paper, and the like. A paper base material such as synthetic paper, a plastic base material such as a polyvinyl chloride sheet, a PET film, a polypropylene film, and a polyethylene film can be used. The surface of the printing medium may be smooth, uneven, or transparent, translucent, or opaque. Further, two or more kinds of these print media may be bonded to each other. Further, a peeling adhesive layer or the like may be provided on the opposite side of the printing surface, or an adhesive layer or the like may be provided on the printing surface after printing. Further, the shape of the base material used in the present invention may be a roll shape or a single leaf shape.

In the present invention, the base material is preferably paper, PET film, polypropylene film, or polyethylene film, and particularly preferably paper base material, in order to fully exhibit the functions of the pretreatment liquid. Further, among the paper base materials, it is particularly preferable to use the pretreatment liquid of the present invention for a poorly absorbent base material such as coated paper, art paper, cast paper, finely coated paper, and synthetic paper. Since these base materials have low liquid permeability, they are particularly liable to cause image defects such as bleeding and color unevenness, waviness, curl, etc., but these problems can be suitably solved by using the pretreatment liquid of the present invention. can.

In the present invention, the "poorly absorbent substrate" has an absorption coefficient for water of 0 to 0.6 ml / m ² as measured by the Bristow method (J. TAPPI pulp and paper test method No. 51-87) shown below. Represents a substrate that is msec ^1/2 . Further, the absorption coefficient can be measured by using, for example, an automatic scanning liquid absorption meter manufactured by Kumagai Riki Kogyo Co., Ltd. Specifically, the relationship diagram between the amount of water absorbed (ml / m ² ) and the square root of the contact time (msec ^1/2 ) obtained between the contact time of 100 to 1000 ms using the above device and water. Therefore, the gradient of the straight line obtained by the least squares method is used as the absorption coefficient.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the following description, "parts" and "%" represent "parts by weight" and "% by weight", respectively, unless otherwise specified.

<Manufacturing example of resin varnish A>
The following materials were mixed for 1 hour with stirring, then heated to 90 ° C. and further mixed for 1 hour. Then, the mixture was allowed to cool to room temperature to obtain a resin varnish A.
25 parts of PVA103 (polyvinyl alcohol manufactured by Kuraray, saponification degree 98-99% (complete saponification), polymerization degree 3
00)
・ 75 copies of ion-exchanged water

<Manufacturing example of resin varnish B>
The following materials were mixed for 1 hour with stirring, then heated to 90 ° C. and further mixed for 1 hour. Then, the mixture was allowed to cool to room temperature to obtain a resin varnish B.
・ PVA103 25 parts ・ PVA217 10 parts (polyvinyl alcohol manufactured by Kuraray, saponification degree 87-89% (partial saponification), polymerization degree 1
700)
・ 75 copies of ion-exchanged water

<Manufacturing example of resin varnish C>
The following materials were mixed for 1 hour with stirring, then heated to 90 ° C. and further mixed for 1 hour. Then, the mixture was allowed to cool to room temperature to obtain a resin varnish C.
・ RS1113 25 parts (modified polyvinyl alcohol manufactured by Kuraray, saponification degree 97-98% (complete saponification))
・ 75 copies of ion-exchanged water

<Manufacturing example of resin varnish D>
The following materials were mixed for 1 hour with stirring, then heated to 90 ° C. and further mixed for 1 hour. Then, it was allowed to cool to room temperature to obtain a resin varnish D.
・ PVA103 55.4 parts ・ Ion exchanged water 44.6 parts

<Production example of pretreatment liquid 1>
The following materials were added sequentially with stirring. The pretreatment liquid 1 was obtained by mixing at room temperature for 1 hour, heating to 60 ° C., mixing for another 1 hour, allowing to cool to room temperature, and filtering with a membrane filter having a pore size of 1 μm.
・ Resin varnish A 20 parts ・ Calcium chloride dihydrate 7.5 parts (manufactured by Tokuyama Corporation)
・ 2-propanol 4 parts ・ Surfinol 465 (acetylene-based surfactant manufactured by Air Products) 0.5 parts ・ Proxel GXL 0.05 parts (preservative, Arch Chemicals 1,2-benzoisothiazole-3-3) On solution)
・ 67.95 parts of ion-exchanged water

<Production example of pretreatment liquids 2-48>
Using the materials shown in Tables 1 to 3 below, pretreatment liquids 2 to 48 were obtained by the same method as in the pretreatment liquid 1.

The materials listed in Tables 1 to 3 are as follows.
・ CaCl 2.2H ₂ O: Calcium chloride _dihydrate・ MgCl 2.6H ₂ O: Magnesium chloride hexahydrate ・ י ₄ : Magnesium sulfate ・ Ca (NO ₃ ) _{2.4H 2} O: Calcium ₄ water nitrate Japanese ・ Zn (CH ₃ COO) 2.2H ₂ O: Zinc acetate _{dihydrate ・ [Al 2 (} OH) _n Cl _6-n ] _m : Polyaluminum chloride (manufactured by Taki Chemical Co., Ltd.)
・ FeSO _{4.7H 2} O: Iron sulphate heptahydrate ・ YNO 3.6H ₂ O: Ithrium nitrate hexahydrate ・ (CH ₃ COO) ₂ Ca ・ H ₂ O: Calcium acetate monohydrate ・₍ CH) ₃ CH (OH) COO) ₂ Ca ・ 5H ₂ O: DL-calcium lactate pentahydrate ・ NH ₄ (C ₂ H ₄ (OH) COO): Ammonium lactate ・ John Krill 1674: Acrylic resin emulsion manufactured by BASF Solid content 45%)
Hydran CP-7020: Cationic urethane resin emulsion manufactured by Dainippon Ink and Chemicals (solid content 40%)
BYK-190: BASF's styrene maleic acid water-soluble resin (solid content 45%, weight average molecular weight 15,000)
Pitzcol K-30: Vinylpyrrolidone water-soluble resin manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. (powder, weight average molecular weight 45,000)
-IPrOH: 2-propanol-MB: 3-methoxybutanol-1,2-PD: 1,2-propanediol-1,2-BuD: 1,2-butanediol-1,2-HexD: 1,2- Hexanediol ・ EDG: Diethylene glycol monoethyl ether ・ PEG # 600: Polyethylene glycol # 600
・ Surfinol 465 (acetylene-based surfactant manufactured by Air Products Co., Ltd.)
-Dynol 607: acetylene-based surfactant manufactured by Air Products Co., Ltd.-TegoWet280: siloxane-based surfactant manufactured by Evonik Degussa Co., Ltd.-ZonylFS-300: fluorosurfactant manufactured by DuPont Co., Ltd.-Proxel GXL (preservative, Arch Chemicals Co., Ltd. 1) , 2-Benzoisothiazole-
3-on solution)

<Production example of pigment dispersion resin 1>
93.4 parts of butanol was charged in a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, and replaced with nitrogen gas. The inside of the reaction vessel is heated to 110 ° C., and a mixture of 40 parts of styrene, 30 parts of acrylic acid, 30 parts of behenyl acrylate as a polymerizable monomer, and 6 parts of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator is mixed. The mixture was added dropwise over 2 hours to carry out a polymerization reaction. After completion of the dropping, the mixture was further reacted at 110 ° C. for 3 hours, then 0.6 part of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the reaction was further continued at 110 ° C. for 1 hour to obtain a solution of the dispersed resin 1. rice field. Further, after cooling to room temperature, 37.1 parts of dimethylaminoethanol was added for neutralization, and then 100 parts of water was added to make it aqueous. Then, the mixture was heated to 100 ° C. or higher, and butanol was azeotropically boiled with water to distill off butanol, and the solid content was adjusted to 30%. From this, an aqueous solution having a solid content of 50% of the pigment dispersion resin 1 was obtained. The pH of the aqueous solution (solid content 30%) of the pigment dispersion resin 1 was 9.7 when measured using a tabletop pH meter F-72 manufactured by HORIBA, Ltd. Further, when the weight average molecular weight of the pigment dispersion resin was measured by the method shown above using HLC-8120GPC manufactured by Tosoh Corporation, it was 22,500.

<Production example of pigment dispersion resin 2>
By using the same method as that of the pigment dispersion resin 1 except that 50 parts of acrylic acid and 50 parts of lauryl methacrylate were used as the polymerizable monomer, an aqueous solution having a solid content of 30% of the pigment dispersion resin 2 was obtained. The pH of the aqueous solution (solid content 30%) of the pigment-dispersed resin 2 was 8.1, and the weight average molecular weight of the pigment-dispersed resin 2 was 15,000.

<Production example of pigment dispersion liquid 1>
20 parts of pigment, 20 parts of an aqueous solution of pigment dispersion resin 1 (solid content 30%), 60 parts of water were mixed, pre-dispersed with a disper, and then filled with 1800 g of zirconia beads having a diameter of 0.5 mm. The main dispersion was carried out for 2 hours using a 1.6 L dynomill to obtain a pigment dispersion liquid 1. The pigments used to make each ink are as follows.
Cyan: LIONOL BLUE 7358G manufactured by Toyo Color Co., Ltd.
(CI Pigment Blue 15: 3)
Magenta: Inkjet Magenta E5B02 manufactured by Clariant AG
(CI Pigment Bio Red 19)
Yellow: LIONOL YELLOW TT-1405G manufactured by Toyo Color Co., Ltd.
(CI Pigment Yellow 14)
Black: PinteX85 manufactured by Orion Engineered Carbons
(Carbon black)

<Production example of pigment dispersion liquid 2>
Pigment dispersion liquid 1 except that an aqueous solution (solid content 30%) of the pigment dispersion resin 2 is used as the pigment dispersion resin and FASTOGEN SUPER MAGENTA RG (CI Pigment Red 122) manufactured by DIC Corporation is used as the Magenta pigment. The pigment dispersion liquid 2 was obtained by using the same method as in the above.

<Production example of water-soluble resin varnish>
20 parts of John Krill 819 (BASF acrylic resin, weight average molecular weight 14,500, acid value 75 mgKOH / g), dimethylaminoethanol 2.38 in a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer. Parts and 77.62 parts of water were added to make it water-soluble. 1 g of this mixed solution was sampled, heated and dried at 180 ° C. for 20 minutes, and the solid content concentration was measured. Based on the obtained solid content concentration, water was added so that the non-volatile content of the produced water-soluble resin varnish was 20% to obtain a water-soluble resin varnish having a solid content concentration of 20%.

<Manufacturing example of CMYK inkjet ink set 1>
The materials described below were sequentially added to the mixing vessel while stirring with a disper, and stirred until sufficiently uniform. Then, filtration was performed with a membrane filter having a pore size of 1 μm. A CMYK inkjet ink set 1 was obtained by using each of the four colors of CMYK as the pigment dispersion liquid 1.
・ Pigment dispersion 1 30 parts ・ Water-soluble resin varnish 13 parts ・ 1,2-butanediol 30 parts ・ Surfinol 465 0.2 parts ・ TegoWet280 0.5 parts ・ Triethanolamine 0.5 parts ・ Proxel GXL 0. 05 parts ・ Ion-exchanged water 25.75 parts

<Manufacturing examples of inkjet ink sets 2 to 12>
Using the materials shown in Table 4 below, inkjet ink sets 2 to 12 were obtained by the same method as for inkjet ink set 1.

Among the materials listed in Table 4, the materials not listed in Tables 1 to 3 are as follows.
-John Krill 538: BASF acrylic resin emulsion, solid content 46%
・ 1,2-PG: 1,2-propanediol ・ 1,2-PenD: 1,2-pentanediol ・ 1,5-PenD: 1,5-pentanediol ・ DEG: diethylene glycol ・ TEG: triethylene glycol ・MFG: Propylene glycol monomethyl ether ・ iPDG: Diethylene glycol monoisopropyl ether ・ BDG: Diethylene glycol monobutyl ether ・ NaOHaq: 4 wt% sodium hydroxide aqueous solution

<Production example 1 of a base material to which a pretreatment liquid is applied>
The pretreatment liquids 1 to 31 prepared above were applied to the printing tester K Rock Spruffer (manufactured by Matsuo Sangyo Co., Ltd.) at the coating speed shown in Table 6 with OK top coat + paper (manufactured by Oji Paper Co., Ltd.). Was evenly applied to. At this time, the WET coating amount was adjusted to ± 0.1 g / m ² of the pretreatment liquid coating amount shown in Table 6 by applying the coating multiple times as needed using ceramic rollers having different numbers of wires.

After applying the pretreatment liquid, it was immediately fixed on a conveyor capable of transporting the base material. After that, the pretreatment liquid was dried by operating the conveyor at a predetermined speed shown in Table 6 and passing it through a box in the transport path having a mechanism for generating hot air at 100 ° C. inside. A substrate to which the pretreatment liquid was applied was prepared. The time when the base material on the conveyor was exposed to hot air in the box was as follows.
・ For transport speed of 75 m / min: 0.8 seconds ・ For transport speed of 50 m / min: 1.2 seconds

<Production example 2 of a base material to which a pretreatment liquid is applied>
One inkjet head KJ4B-QA (manufactured by Kyocera Corporation) was installed on the upper part of the conveyor capable of transporting the base material, and the pretreatment liquids 32 to 48 prepared above were filled in each. The inkjet head has a design resolution of 600 dpi and a maximum drive frequency of 30 kHz, and when printing is performed at the maximum drive frequency and a printing speed of 75 m / min, the recording resolution in the substrate transport direction is 600 dpi.

Next, after fixing the base material to which the pretreatment liquid is applied on the conveyor, the conveyor is driven at the speed shown in Table 7, and when passing through the installation portion of the inkjet head, the pretreatment liquid is dropped with a drop volume of 12 pL. A solid pretreatment liquid layer having a printing rate of 100% was prepared by discharging. The amount of WET applied at this time was 6 ± 0.2 g / m ² .
After that, the conveyor is operated at the speed shown in Table 7 and passed through a box in the transport path equipped with a mechanism for generating hot air at 100 ° C. to dry the pretreatment liquid and pretreat. A substrate to which the liquid was applied was prepared.

<Manufacturing example of inkjet ink printed matter>
Four inkjet heads KJ4B-QA (manufactured by Kyocera) were installed on the upper part of the conveyor capable of transporting the base material, and the inkjet ink sets were filled in the order of CMYK from the upstream side.
Next, after fixing the base material to which the pretreatment liquid is applied on the conveyor, the conveyor is driven at the speed shown in Table 8, and when passing through the installation portion of the inkjet head, the inkjet ink is dropped in the order of CMYK. The ink was discharged at a volume of 12 pL, and sample number 5 (bicycle) of high-definition color digital standard image data (ISO / JIS-SCID JISX9201 compliant JSA-00001) was printed. Immediately after printing, the substrate was fixed on a conveyor capable of transporting the substrate. After that, the conveyor was operated at the speed shown in Table 8 and passed through a box provided with a mechanism for generating hot air at 100 ° C. inside in the transport path to prepare an inkjet ink printed matter.

The combinations of the pretreatment liquid and the inkjet ink used in the production of the printed matter are as shown in Table 8 below.

Here, the relationship between the conveyor transfer speed and the drive frequency of the inkjet head in the application of the pretreatment liquid and the printing of the inkjet ink set performed by the above-mentioned inkjet method is shown in Table 5 below.

<Production example of a base material to which a pretreatment liquid to which a dye is added is applied>
In order to improve visibility, 0.1 g of KayafectRed PLiquid (dye manufactured by Nippon Kayaku Co., Ltd.) was added to 10 g of each of the pretreatment liquids 1 to 31 prepared above, and the mixture was well mixed and dissolved. The pretreatment liquid to which the dye was added was uniformly applied to OK top coat + paper (manufactured by Oji Paper Co., Ltd.) using a printing tester K-rock sprufer (manufactured by Matsuo Sangyo Co., Ltd.). At this time, by using ceramic rollers having different numbers of wires and applying the coating multiple times as necessary, the WET coating amount can be adjusted to ± 0.1 g / m ² of the pretreatment liquid coating amount shown in Table 6. One pretreatment liquid was coated at three coating speeds of 30 m / min, 50 m / min, and 75 m / min.

Immediately after applying the pretreatment liquid to which the dye was added, the base material was placed in an air oven at 50 ° C. and dried for 3 minutes to prepare a base material to which the pretreatment liquid to which the dye was added was applied.

<Evaluation>
The base material to which the pretreatment liquid was applied, the inkjet ink printed matter, and the base material to which the pretreatment liquid to which the dye was added, which were prepared above, were evaluated as shown below. The evaluation results are as shown in Tables 6-8.

<Evaluation of uneven coating of pretreatment liquid>
The coating (printing) suitability of the pretreatment liquids 1 to 31 was evaluated by visually observing the degree of color unevenness of the base material to which the pretreatment liquid to which the dye was added, which was prepared by changing the coating speed. .. The evaluation results are as follows, and those with Δ or higher are considered to be good.
⊚: No uneven coating was observed in those coated at any speed.
◯: No uneven coating was observed at 50 m / min or less, and uneven coating was observed at 75 m / min.
Δ: No coating unevenness was observed at 30 m / min, and coating unevenness was observed at 50 m / min or more.
X: Uneven coating was observed in all the coatings at any speed.

<Evaluation of discharge stability of pretreatment liquid>
The printability of the pretreatment liquids 32 to 48 was evaluated by evaluating the ejection stability by the following method. In order to improve visibility, 0.1 g of KayafectRedPLiquid was added to 10 g of each of the pretreatment liquids 32 to 48, mixed well and dissolved, and then into an inkjet ejection device equipped with an inkjet head KJ4B-QA (manufactured by Kyocera). Filled. After confirming that there is no nozzle omission, discharge is performed continuously for 2 hours under the conditions of a drop volume of 5 pL and a drive frequency of 30 kHz, then a nozzle check pattern is printed and the number of nozzle omissions is counted to prepare the pretreatment liquid. The discharge stability of 32 to 48 was evaluated. The evaluation criteria were as follows, and Δ or higher was considered good.
⊚: Nozzle omission was not found in the nozzle check pattern 2 hours after the start of printing ○: Nozzle omission was 1 to 2 in the nozzle check pattern 2 hours after the start of printing Δ: Nozzle check 2 hours after the start of printing 3 to 4 nozzles missing in the pattern ×: 5 or more nozzles missing in the nozzle check pattern 2 hours after the start of printing

<Evaluation of pretreatment liquid dryness>
Another OK top coat + paper was layered on the base material to which the pretreatment liquid prepared above was applied, a load of 200 g was applied from above, and the mixture was allowed to stand at 25 ° C. for 24 hours. After that, the stacked OK top coat + paper was peeled off, and the set-off of the pretreatment liquid layer was confirmed. In addition, the base material to which the pretreatment liquid was applied immediately after preparation was rubbed 10 times with a cotton swab, and the dryness of the base material was evaluated together with the result of set-off. The evaluation results are as follows, and those with Δ or higher are considered to be good.
⊚: No pretreatment liquid adhered to the cotton swab after 10 reciprocating rubbing, and no set-off was observed.
◯: Adhesion of the pretreatment liquid was observed on the cotton swab by rubbing 5 times, but no set-off was observed.
Δ: 1 The pretreatment liquid was observed to adhere to the cotton swab by rubbing back and forth, but no set-off was observed.
X: Both the pretreatment liquid adhered to the cotton swab and the set-off was observed.

<Tack evaluation>
Another OK top coat + paper was layered on the base material to which the pretreatment liquid prepared above was applied, a load of 200 g was applied from above, and the mixture was allowed to stand for 24 hours under warming and humidifying conditions of 35 ° C. and 80%. After that, the stacked OK top coat + paper was peeled off, and the set-off of the pretreatment liquid was confirmed. In addition, after standing still under warming and humidifying conditions, the base material to which the pretreatment liquid was applied was rubbed back and forth 10 times with a cotton swab, and the tack of the base material was evaluated together with the result of set-off. The evaluation results are as follows, and those with Δ or higher are considered to be good.
⊚: No pretreatment liquid adhered to the cotton swab after 10 reciprocating rubbing, and no set-off was observed.
◯: Adhesion of the pretreatment liquid was observed on the cotton swab by rubbing 5 times, but no set-off was observed.
Δ: 1 The pretreatment liquid was observed to adhere to the cotton swab by rubbing back and forth, but no set-off was observed.
X: Both adhesion of the pretreatment liquid to the cotton swab and set-off were observed.

<Evaluation of helicopter coating unevenness>
For the pretreatment liquids 1 to 31, helicopter coating unevenness was evaluated by the following method. The film thickness uniformity of the helicopter in the coated part was evaluated by visually observing the degree of uneven coating of the helicopter on the base material to which the pretreatment liquid to which the dye was added, which was prepared by changing the coating speed. .. The evaluation results are as follows, and those with Δ or higher are considered to be good.
⊚: No helicopter coating unevenness was observed in those coated at any speed.
◯: No helicopter coating unevenness was observed at 50 m / min or less, and coating unevenness was observed at 75 m / min.
Δ: Edge coating unevenness was not observed at 30 m / min, and coating unevenness was observed at 50 m / min or more.
X: Helicopter coating unevenness was observed in all the coatings at any speed.

<Evaluation of bleeding>
Visually observe the image quality of the 4C (CMYK) printing unit (the image of the clock existing in the printed matter of the high-definition color digital standard image data (sample number 5)) of the inkjet ink printed matter, and increase the dot shape by 200 times with a microscope. The bleeding was evaluated by magnifying and observing. The evaluation results are as follows, and those with Δ or higher are considered to be good.
⊚: No bleeding was visually observed, and the dots were independent even with a microscope, and no bleeding was observed.
◯: No bleeding was visually observed, and the microscope showed independent up to 3C (CMY) dots, but only K discharged to the uppermost part was slightly elliptical and bleeding was observed.
Δ: No bleeding was visually observed, and the dots up to 2C (CM) were independent under the microscope, but Y and K were slightly elliptical and bleeding was observed.
X: Blurring was visually observed, and the dots in the 4C printing portion had M, Y, and K not retaining the circular shape, and color mixing occurred.

<Evaluation of ink dryness>
Another OK top coat + paper was layered on the inkjet ink printed matter, a load of 200 g was applied from above, and the mixture was allowed to stand at 25 ° C. for 24 hours. After that, the stacked OK top coat + paper was peeled off, and the ink set-off was confirmed. Immediately after creation, the 4C (CMYK) printed matter (the image of the clock existing in the printed matter of the high-definition color digital standard image data (sample number 5)) of the inkjet ink printed matter was rubbed 10 times with a cotton swab, and the result of set-off was obtained. At the same time, the dryness of the printed matter was evaluated. The evaluation results are as follows, and those with Δ or higher are considered to be good.
⊚: No ink adhered to the cotton swab after 10 reciprocating rubs, and no set-off was observed.
◯: Ink adhered to the cotton swab after 5 round trips, but no set-off was observed.
Δ: Ink adhered to the cotton swab by rubbing back and forth, but no set-off was observed.
X: Both ink adhesion to the cotton swab and set-off were observed.

<Evaluation of cracks>
Visually observe the coating film cracks on the 4C (CMYK) printed matter (the image of the clock present in the printed matter of the high-definition color digital standard image data (sample number 5)) of the inkjet ink printed matter, and at the same time, check for the presence or absence of fine cracks. The cracks were evaluated by observing with a microscope at 200 times. The evaluation results are as follows, and those with Δ or higher are considered to be good cracks.
⊚: No cracks were visually observed, and no cracks were observed with a microscope.
◯: No cracks were visually observed, and one or two fine cracks were observed under the microscope.
Δ: No cracks were visually observed, and 3 to 5 fine cracks were observed under the microscope.
X: Large cracks that can be visually confirmed were observed.

<Evaluation of solid filling>
Using the equipment used in the manufacture of the inkjet ink printed matter, using cyan (C), magenta (M), yellow (Y), and black (K) inks one color at a time, OK top coat + paper (Oji Paper Co., Ltd.) A solid printed matter was produced by ejecting the ink to a drop volume of 12 pL (manufactured by the company).
For the solid printed matter of each color prepared above, the solid filling was evaluated by visually and microscopically observing whether there was a part where the base material was exposed due to insufficient filling. The evaluation results are as follows, and those with Δ or higher are considered to be good. The evaluation was performed for all CMYK colors, and the one with the worst evaluation is shown in Table 8.
⊚: The solid part was completely filled by both visual and microscopic observation. ○: A part of the light color was observed by visual observation, but it was sufficiently filled by visual observation. The visible part was observed, but it was sufficiently filled by visual inspection. ×: Uneven density was visually observed, or the substrate was exposed.

<Evaluation of water resistance>
The solid printed matter of each color was rubbed 10 times with a cotton swab soaked in water to evaluate the water resistance of the printed matter. The evaluation results are as follows, and those with Δ or higher are considered to be good. The evaluation was performed for all CMYK colors, and the one with the worst evaluation is shown in Table 8.
⊚: No ink adhered to the cotton swab even after 10 round trips.
◯: No ink adhered to the cotton swab in 7 round trips, but ink adhered to the cotton swab within 10 round trips.
Δ: No ink adhered to the cotton swab within 5 round trips, but ink adhered to the cotton swab within 7 round trips.
X: Ink adhered to the cotton swab within 5 round trips.

<Evaluation of concentration>
For the solid printed matter of each color, the OD value was measured with the light source D50, the viewing angle of 2 °, and the status E in the CIE color system using the spectrocolorimeter X-RITE528. In each of the magenta, yellow, and cyan color regions, it was evaluated whether or not the density was high when compared with Japan Color 2011. The evaluation results are as follows, and a value of Δ or higher is judged to be a practical level.
⊚: The density was 0.1 or more higher than Japan Color 2011 in all of Magenta, Yellow, and Cyan. ○: The density was higher in the range of 0 to 0.1 than Japan Color 2011 in any one of Magenta, Yellow, and Cyan. , 0.1 or more higher than Japan Color 2011 in any two regions Δ: Density was higher in the range of 0 to 0.1 than Japan Color 2011 in any two regions of Magenta, Yellow, Cyan, and any 1 Higher than Japan Color 2011 in one area ×: Density was lower than Japan Color 2011 in all magenta, yellow, and cyan

<Evaluation of discharge stability>
An inkjet ejection device equipped with an inkjet head KJ4B-QA (manufactured by Kyocera Corporation) was prepared and filled with black inkjet ink. After confirming that there is no nozzle omission, ejection is performed continuously for 2 hours under the conditions of a drop volume of 5 pL and a drive frequency of 30 kHz, and then a nozzle check pattern is printed to count the number of nozzle omissions for ejection stability. Was evaluated. The evaluation criteria were as follows, and Δ or higher was considered good.
⊚: Nozzle omission was not found in the nozzle check pattern 2 hours after the start of printing ○: Nozzle omission was 1 to 2 in the nozzle check pattern 2 hours after the start of printing Δ: Nozzle check 2 hours after the start of printing 3 to 4 nozzles missing in the pattern ×: 5 or more nozzles missing in the nozzle check pattern 2 hours after the start of printing

The method for producing a pretreatment liquid, an ink set, and a printed matter of the present invention can obtain a high-quality image regardless of the substrate, and is particularly suitably used for high-speed, high-recording-resolution inkjet printing. be able to.

Claims (14)

An ink set for a paper base material or a film base material, which comprises a pretreatment liquid used in a method of printing in contact with a base material and a water-based inkjet ink.
The water-based inkjet ink contains a pigment, a water-soluble organic solvent, a water-soluble binder resin, and water.
The pretreatment liquid contains a dissolved inorganic metal salt and / or an organic metal salt, an organic solvent, a water-soluble binder resin, a surfactant, and water.
The metal ion derived from the inorganic metal salt and / or the organometallic salt contains a polyvalent metal ion, and the content of the polyvalent metal ion is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid. ,
The organic solvent contains a compound containing one or more hydroxyl groups in its molecular structure (excluding those which are surfactants) , and the content of the organic solvent having a boiling point of 180 ° C. or higher is the total amount of the pretreatment liquid. It is 15% by weight or less with respect to
Compounds containing one or more hydroxyl groups in the molecular structure include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1. -Butanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentane Dire, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3 -Propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1 , 3-Propanediol, 2-methylpentane-2,4-diol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, diethylene glycol, triethylene glycol, polyethylene glycol # 200, polyethylene glycol # 400 , Ethylene Glycol # 600, Dipropylene Glycol, Butylene Glycol, Dibutylene Glycol, Glycerin, Ethylene Glycol Monoethyl Ether, Ethylene Glycol Monobutyl Ether, Diethylene Glycol Monomethyl Ether, Diethylene Glycol Monoethyl Ether, Diethylene Glycol Monopropyl Ether, Diethylene Glycol Monobutyl Ether, Diethylene Glycol Mono Pentyl Ether, Diethylene Glycol Monohexyl Ether, Triethylene Glycol Monomethyl Ether, Triethylene Glycol Monoethyl Ether, Triethylene Glycol Monopropyl Ether, Triethylene Glycol Monobutyl Ether, Tetraethylene Glycol Monomethyl Ether, Tetraethylene Glycol Monoethyl Ether, Tetraethylene Glycol Monobutyl Ether, Ethylene Glycol Monomethyl Ether, Ethylene Glycol Monoethyl Ether, Ethylene Glycol Monopropyl Ether, Ethylene Glycol Monobutyl Ether, Dipropylene Glycol Monomethyl Ether, Dipropylene Glycol Monoethyl Ether, Dipropylene Glycol Monopropyl Ether, Tripropi One or more compounds selected from the group consisting of reneglycol monomethyl ether and tripropylene glycol monoethyl ether.
The number average molecular weight (Mn) of the water-soluble binder resin contained in the pretreatment liquid is 3,000 to 90,000.
The surfactant is a siloxane-based and / or acetylene-based surfactant.
An ink set characterized in that the acid value of the water-soluble binder resin contained in the water-based inkjet ink is 10 to 80 mgKOH / g . An ink set for a paper base material or a film base material, which comprises a pretreatment liquid used in a non-contact printing method with a base material and a water-based inkjet ink.
The water-based inkjet ink contains a pigment, a water-soluble organic solvent, a water-soluble binder resin, and water.
The pretreatment liquid contains a dissolved inorganic metal salt and / or an organic metal salt, an organic solvent, a water-soluble binder resin, a surfactant, and water.
The metal ion derived from the inorganic metal salt and / or the organometallic salt contains a polyvalent metal ion, and the content of the polyvalent metal ion is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid. ,
The organic solvent contains a compound containing one or more hydroxyl groups in its molecular structure (excluding those which are surfactants), and the content of the organic solvent having a boiling point of 180 ° C. or higher is the total amount of the pretreatment liquid. It is 15% by weight or less with respect to
Compounds containing one or more hydroxyl groups in the molecular structure include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1. -Butanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentane Dire, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3 -Propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1 , 3-Propanediol, 2-methylpentane-2,4-diol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, diethylene glycol, triethylene glycol, polyethylene glycol # 200, polyethylene glycol # 400 , Ethylene Glycol # 600, Dipropylene Glycol, Butylene Glycol, Dibutylene Glycol, Glycerin, Ethylene Glycol Monoethyl Ether, Ethylene Glycol Monobutyl Ether, Diethylene Glycol Monomethyl Ether, Diethylene Glycol Monoethyl Ether, Diethylene Glycol Monopropyl Ether, Diethylene Glycol Monobutyl Ether, Diethylene Glycol Mono Pentyl Ether, Diethylene Glycol Monohexyl Ether, Triethylene Glycol Monomethyl Ether, Triethylene Glycol Monoethyl Ether, Triethylene Glycol Monopropyl Ether, Triethylene Glycol Monobutyl Ether, Tetraethylene Glycol Monomethyl Ether, Tetraethylene Glycol Monoethyl Ether, Tetraethylene Glycol Monobutyl Ether, Ethylene Glycol Monomethyl Ether, Ethylene Glycol Monoethyl Ether, Ethylene Glycol Monopropyl Ether, Ethylene Glycol Monobutyl Ether, Dipropylene Glycol Monomethyl Ether, Dipropylene Glycol Monoethyl Ether, Dipropylene Glycol Monopropyl Ether, Tripropi One or more compounds selected from the group consisting of reneglycol monomethyl ether and tripropylene glycol monoethyl ether.
The weight average molecular weight (Mw) of the water-soluble binder resin contained in the pretreatment liquid is 3,000 to 50,000.
The surfactant is a siloxane-based and / or acetylene-based surfactant.
An ink set characterized in that the acid value of the water-soluble binder resin contained in the water-based inkjet ink is 10 to 80 mgKOH / g. The ink set according to claim 1 , wherein the water-soluble binder resin contained in the pretreatment liquid contains a nonionic water-soluble resin. The ink set according to claim 1 or 3, wherein the compound containing one or more hydroxyl groups in the molecular structure contains monohydric alcohols. The pretreatment liquid is characterized in that the content of the organic solvent having a surface tension of 20 to 32 mN / m at 25 ° C. is 35 to 100% by weight with respect to the total amount of the organic solvent in the pretreatment liquid. The ink set according to any one of claims 1 to 4. The invention according to any one of claims 1 to 5 , wherein the weight ratio of the content of the binder resin to the content of the metal ion derived from the inorganic metal salt and / or the organometallic salt is more than 0 and less than 20. Ink set. The ink set according to any one of claims 1 to 6 , wherein the surface tension of the pretreatment liquid is 20 to 45 mN / m. The claim is characterized in that the water-soluble organic solvent contained in the water-based inkjet ink contains two or more kinds of glycol ether-based solvent and / or alkyl polyol-based solvent having a boiling point of 180 ° C. or higher and 250 ° C. or lower at 1 atm. The ink set according to any one of Items 1 to 7 . Claims 1 to 1, wherein the water-based inkjet ink contains 0% by weight or more and less than 10% by weight based on the total amount of the water-based inkjet ink, which is a water-soluble organic solvent having a boiling point of 240 ° C. or higher at 1 atm. 8 The ink set described in any of the above. The ink set according to any one of claims 1 to 9 , wherein the water-based inkjet ink substantially does not contain a polymerizable monomer. The water-based inkjet ink is characterized by containing 0% by weight or more and less than 20% by weight based on the total amount of the water-based inkjet ink, which is a water-soluble organic solvent having a boiling point of 210 ° C. or higher at 1 atm. 10 The ink set according to any one. The ink set according to any one of claims 1 to 11 , wherein the water-based inkjet ink contains a pigment in an amount of 2% by weight or more and less than 15% by weight based on the total amount of the water-based inkjet ink. A method for producing a water-based inkjet ink printed matter using the ink set according to any one of claims 1 to 12, wherein a pretreatment liquid is applied to a substrate conveyed at a speed of 30 m / min or more, and the pretreatment. Production of a water-based inkjet ink printed matter comprising a step of applying the water-based inkjet ink to a portion to which the liquid is applied by a one-pass printing method , wherein the base material is a paper base material or a film base material. Method. The method for producing a water-based inkjet ink printed matter according to claim 13, wherein the amount of the pretreatment liquid applied is 1 to 25 g / m ² .