JP6088863B2 - Aqueous pigment ink composition for inkjet recording and image forming method - Google Patents

Description

  The present invention relates to an aqueous pigment ink composition for inkjet recording and an image forming method.

  As an image recording method for forming an image on a recording medium such as paper based on an image data signal, an electrophotographic method, a sublimation type / melting type thermal transfer method, an ink jet method and the like are known. Among these, the ink jet method can be implemented with an inexpensive apparatus, and ink can be directly formed on a recording medium by ejecting ink only to a required image portion, so that ink can be used efficiently. It is possible to reduce the running cost, further reduce noise, and is excellent as an image recording method.

  However, inks (inkjet recording inks) used in the above-described ink jet method are mainly water-based inks, and are suitable for printing on ink-absorbing materials such as paper. Thus, it is not suitable for printing on a material having no ink absorption or a material having low ink absorption (non-ink-absorbing material).

  Thus, many proposals have been made on ink jet recording inks that can be printed on non-ink-absorbing materials such as plastic and metal. For example, Patent Document 1 proposes an aqueous pigment ink composition that improves water resistance, improves the quality of printed images such as dyeing fastness such as diffusion resistance and abrasion resistance, and improves long-term storage stability. Yes. Patent Document 2 proposes an aqueous pigment ink composition having excellent ejection stability. Patent Document 3 proposes an aqueous pigment ink containing latex (emulsion) and a surfactant. Further, Patent Document 4 proposes an aqueous pigment ink composition that has less unevenness of ink density, bleeding, color mixing, and the like, and is excellent in ejection stability. Patent Document 5 proposes an aqueous pigment ink that includes a color pigment, water, a resin, a water-soluble organic solvent, and a nozzle clogging preventing agent and has excellent ejection stability. In Patent Document 6, an aqueous pigment containing water, a water-soluble organic solvent, a surfactant-dispersed pigment, and a resin-coated pigment, and improving the quality of printed images such as storage stability and ejection reliability, and image fastness Ink has been proposed.

JP 2006-213922 A JP 2008-1787 A Special table 2011-507991 gazette JP 2009-235154 A JP 2010-18742 A JP 2012-251060 A

  However, since the aqueous pigment ink compositions described in Patent Documents 1 and 2 do not contain a binder such as an emulsion resin, when the recording medium is an ink non-absorbing material such as plastic or metal, the recording target There is a problem that the adhesion of the ink to the medium is poor.

  The aqueous pigment ink described in Patent Document 3 contains latex (emulsion), but it needs to be dried at a relatively high temperature exceeding 90 ° C. in order to make the ink adhere to the recording medium. Depending on the material of the medium, there is a problem that the recording medium is deformed.

  Further, in Patent Document 4, drying for bringing the ink into close contact with the recording medium is performed at a low temperature of 80 ° C. or less, but the coating film characteristics (water resistance, drying property, chemical resistance, adhesion property, etc.) at low temperature drying. ) And there is still room for improvement in the quality of printed images.

  In addition, the water-based pigment inks described in Patent Documents 5 and 6 still have room for improvement in coating film characteristics at low temperature drying and the quality of printed images.

  SUMMARY OF THE INVENTION The present invention solves the above problems, and is an aqueous pigment ink composition for ink jet recording that is excellent in ejection stability and coating film properties by low-temperature drying, and can realize high quality printed images, and the ink jet recording. An image forming method using the aqueous pigment ink composition is provided.

  In order to solve the above problems, an aqueous pigment ink composition for inkjet recording of the present invention is an aqueous pigment ink composition for inkjet recording comprising a surfactant-dispersed pigment, an emulsion resin, water, and an organic solvent, The glass transition temperature of the emulsion resin is 60 ° C. or higher, and the content of the emulsion resin is 5% by weight or more and less than 30% by weight based on the total amount of the aqueous pigment ink composition for inkjet recording, and the organic solvent Is characterized by containing an organic solvent having a boiling point of 285 ° C. or lower in a range of 10 wt% or more and 40 wt% or less with respect to the total amount of the aqueous pigment ink composition for ink jet recording.

  The image forming method of the present invention includes an ejection step of ejecting the water-based pigment ink composition for ink-jet recording of the present invention from an ink-jet head and adhering it to the recording medium, and the water-based pigment for ink-jet recording adhered to the recording medium. And a heating step of heating the ink composition to 40 ° C. or higher and 80 ° C. or lower.

  ADVANTAGE OF THE INVENTION According to this invention, the aqueous pigment ink composition for inkjet recording which is excellent in discharge stability and the coating-film characteristic by low-temperature drying, and can implement | achieve the quality improvement of a printed image, and an image formation method using the same can be provided. .

  In general, when a binder such as an emulsion resin is contained in the ink, chemical resistance is improved and the quality of the printed image can be improved. However, if the content of the emulsion resin is increased, the ejection stability may be deteriorated. Are known. However, as a result of intensive studies by the present inventors, an ink composition having good ejection stability and good coating film characteristics at low temperature drying even when the content of the emulsion resin is increased is found, and the present invention is completed. It came to.

  That is, the water-based pigment ink composition for ink-jet recording of the present invention is a water-based pigment ink composition for ink-jet recording containing a surfactant-dispersed pigment, an emulsion resin, water, and an organic solvent. The transition temperature is 60 ° C. or higher, the content of the emulsion resin is 5% by weight or more and less than 30% by weight with respect to the total amount of the aqueous pigment ink composition for inkjet recording, and the organic solvent is used for the inkjet recording. An organic solvent having a boiling point of 285 ° C. or lower is contained in the range of 10% by weight to 40% by weight with respect to the total amount of the aqueous pigment ink composition. This makes it possible to improve the ejection stability and the coating properties (particularly, the drying property, chemical resistance, and adhesion) by low-temperature drying, and an aqueous pigment ink for ink-jet recording capable of realizing high quality printed images. Can be provided.

  Hereinafter, each component of the aqueous pigment ink composition for inkjet recording of the present invention will be described in detail.

(Surfactant dispersed pigment)
The surfactant-dispersed pigment used in the aqueous pigment ink composition for inkjet recording of the present invention contains a pigment, a surfactant as a dispersant, and water, and the pigment is dispersed and stabilized with the surfactant. It is a pigment dispersion. Various additives may be added to the surfactant-dispersed pigment as necessary.

<Pigment>
As the pigment contained in the surfactant-dispersed pigment, conventionally known inorganic pigments and organic pigments can be used.

  Examples of the inorganic pigment include titanium oxide, zinc oxide, zinc oxide, tripone, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, cadmium red, and red rose. Molybdenum red, chrome vermilion, molybdate orange, yellow lead, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, pyridiane, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, ultramarine blue, bitumen , Cobalt blue, cerulean blue, manganese violet, cobalt violet, mica and the like.

  Examples of the organic pigment include azo, azomethine, polyazo, phthalocyanine, quinacridone, anthraquinone, indigo, thioindigo, quinophthalone, benzimidazolone, and isoindoline. Further, as the organic pigment, carbon black made of acidic, neutral or basic carbon, hollow particles of crosslinked acrylic resin, or the like can be used.

  Specific examples of the above-described pigment include compounds classified as pigments in the color index (CI: issued by The Society of Dyers and Colorists) as shown below, that is, the color index (C.I. ) Numbers are given.

  Examples of the pigment having a cyan color include C.I. I. Pigment blue 1, C.I. I. Pigment blue 2, C.I. I. Pigment blue 3, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. And CI Pigment Blue 60. Among these, from the viewpoint of weather resistance, coloring power, etc., C.I. I. Pigment blue 15: 3 and C.I. I. It is preferable to use any one of CI Pigment Blue 15: 4, or a mixture of both.

  Examples of pigments having a magenta color include C.I. I. Pigment red 5, C.I. I. Pigment red 7, C.I. I. Pigment red 12, C.I. I. Pigment red 48 (Ca), C.I. I. Pigment red 48 (Mn), C.I. I. Pigment red 57 (Ca), C.I. I. Pigment red 57: 1, C.I. I. Pigment red 112, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 168, C.I. I. Pigment red 184, C.I. I. Pigment red 202, C.I. I. Pigment red 209, C.I. I. Pigment red 254, C.I. I. Pigment violet 19 and the like. Among these, from the viewpoint of weather resistance, coloring power, etc., C.I. I. Pigment red 122, C.I. I. Pigment red 202, C.I. I. Pigment red 209, C.I. I. Pigment red 254, and C.I. I. At least one selected from the group consisting of CI Pigment Violet 19 is preferred.

  Examples of the pigment having a yellow color include C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 2, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14C, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 75, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 130, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 139, C.I. I. Pigment yellow 147, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 213, C.I. I. And CI Pigment Yellow 214. Among these, from the viewpoint of weather resistance and the like, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 139, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 213, and C.I. I. At least one selected from the group consisting of CI Pigment Yellow 214 is preferred.

  Examples of pigments having a black color include “HCF”, “MCF”, “RCF”, “LFF”, “SCF” manufactured by Mitsubishi Chemical Corporation; “Monarch”, “Regal” manufactured by Cabot Corporation; Degussa Huls “Color Black”, “Special Black”, “Printex” manufactured by Tokai Carbon; “Toka Black” manufactured by Tokai Carbon; “Raven” manufactured by Columbia; Among these, “HCF # 2650”, “HCF # 2600”, “HCF # 2350”, “HCF # 2300”, “MCF # 1000”, “MCF # 980”, “MCF # 970” manufactured by Mitsubishi Chemical Corporation “MCF # 960”, “MCF88”, “LFFMA7”, “LFFMA8”, “LFFMA11”, “LFFMA77”, “LFFMA100”, and “Printex 95”, “Printex 85” manufactured by Degussa Huls, At least one selected from the group consisting of “printex 75”, “printex 55”, and “printex 45” is preferable.

  The above pigments may be used alone or in combination of two or more.

  The pigment concentration in the aqueous pigment ink composition for ink-jet recording of the present invention is preferably from 0.1% by weight to 20% by weight, and more preferably from 0.3% by weight to 10% by weight. When the pigment concentration is less than 0.1% by weight, the printed image tends to lack sharpness. When the pigment concentration exceeds 20% by weight, not only the effect as a colorant is saturated but also the ink viscosity increases and the ejection is stable. It tends to get worse.

<Surfactant>
Surfactants contained in the surfactant-dispersed pigment include alkane sulfonates, α-olefin sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, acyl methyl taurates, and dialkyl sulfo oxalates. , Amphoteric surfactants such as alkyl sulfate ester salts, sulfated olefins, polyoxyethylene alkyl ether sulfate ester salts, alkyl phosphate ester salts, alkyl dimethyl betaine; polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxy Nonionic surfactants such as ethylene alkyl ester, polyoxyethylene alkyl amide, glycerin alkyl ester, and sorbitan alkyl ester;

  In the surfactant-dispersed pigment, the content ratio (weight ratio) between the pigment and the surfactant is preferably 100: 1 to 100: 100, and more preferably 100: 5 to 100: 50. . When the content ratio of the surfactant to the pigment is too small, a pigment dispersion tends to be not obtained. On the other hand, when the content ratio of the surfactant to the pigment becomes too large, the coating properties (particularly water resistance and chemical resistance) due to low temperature drying tend to be inferior.

  The surfactant-dispersed pigment includes the pigment, the surfactant, water, and various additives as necessary, such as a bead mill, a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, It is obtained by dispersing using a dispersing device such as an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, or a wet jet mill.

(Emulsion resin)
As the emulsion resin used in the aqueous pigment ink composition for inkjet recording of the present invention, an emulsion resin having a glass transition temperature of 60 ° C. or higher is preferable. If the glass transition temperature of the emulsion resin is less than 60 ° C., chemical resistance may not be sufficiently obtained, the printing surface may become sticky and dust may easily adhere, or may become sticky. May occur. The upper limit of the glass transition temperature of the emulsion resin is usually about 110 ° C. In this specification, “emulsion resin” means an emulsified resin and does not include an emulsion dispersion medium. The “glass transition temperature of the emulsion resin” means that the aqueous emulsion containing the emulsion resin (emulsion resin dispersion) is dried at 150 ° C. for 2 hours and dehydrated, and the resulting emulsion resin is measured alone. Refers to the glass transition temperature.

  As a material for forming an emulsion resin having a glass transition temperature of 60 ° C. or higher and 110 ° C. or lower, in addition to styrene, tetrahydrofurfuryl acrylate and butyl methacrylate, (α, 2, 3 or 4) -alkyl styrene, (α, 2, 3 or 4) -alkoxystyrene, 3,4-dimethylstyrene, α-phenylstyrene, divinylbenzene, vinylnaphthalene, dimethylamino (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropylacrylamide, N, N— Dimethylaminoethyl acrylate, acryloylmorpholine, N, N-dimethylacrylamide, N-isopropylacrylamide, N, N-diethylacrylamide, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth ) Acrylate, ethylhexyl (meth) acrylate, other alkyl (meth) acrylates, methoxydiethylene glycol (meth) acrylate, (meth) acrylate of ethoxy group diethylene glycol or polyethylene glycol, propoxy group diethylene glycol or polyethylene glycol (meth) acrylate , (Meth) acrylate of diethylene glycol or polyethylene glycol having butoxy group, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, hydroxyalkyl (meth) acrylate, other fluorine-containing (Meth) acrylate, chlorine-containing (meth) acrylate, silicon-containing (meth) acrylic Over doors and the like. In addition, when introducing a crosslinked structure in addition to a monofunctional group such as (meth) acrylamide, maleic acid amide, (meth) acrylic acid, (mono, di, tri, tetra, poly) ethylene glycol di (meth) acrylate, Di (meth) acrylates such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol and 1,10-decanediol, trimethylolpropane tri (meth) acrylate , Glycerin (di, tri) (meth) acrylate, di (meth) acrylate of ethylene oxide adduct of bisphenol A or F, neopentyl glycol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) ) Acrylate etc. can be used

  The content of the emulsion resin is 5% by weight or more and less than 30% by weight with respect to the total amount of the aqueous pigment ink composition for ink jet recording. When the content of the emulsion resin is 30% by weight or more, the discharge stability is lowered, and when the content of the emulsion resin is less than 5% by weight, the coating properties (particularly water resistance and chemical resistance) are reduced by low temperature drying. And adhesion) tend to be inferior.

(Organic solvent)
The aqueous pigment ink composition for inkjet recording of the present invention contains an organic solvent for promoting drying, improving ejection stability of the inkjet head, and imparting moisture retention.

  In the aqueous pigment ink composition for inkjet recording of the present invention, the organic solvent having a boiling point of 285 ° C. or lower is 10 wt% or more and 40 wt% or less with respect to the total amount of the aqueous pigment ink composition for inkjet recording. Preferably, it is contained within the range of 15 wt% or more and 35 wt% or less. When the content of the organic solvent having a boiling point of 285 ° C. or lower exceeds 40% by weight, the coating properties (particularly, drying properties, chemical resistance, and adhesion) due to low temperature drying are deteriorated or the coating is whitened. (Here, the whitening of the coating means that the value of L is increased in the La * b * color system) and is not suitable for use as an aqueous pigment ink for inkjet recording. When the amount is less than 10% by weight, the ejection stability tends to deteriorate.

  Examples of the organic solvent having a boiling point of 285 ° C. or lower include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,2-propanediol, 1 , 3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl -1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 3,5-dimethyl-3-hexyne-2,5- Diol, 2,5-hexanediol, hexylene glycol, 1,6-hexanediol, 2 Ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,5-dimethyl-2,5-hexanediol, sulfolane, 1,4-cyclohexanedimethanol, 2,2 -Thiodiethanol, 3-pyridyl carbinol, propylene glycol monomethyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, tripropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol t- Chill ether, dipropylene glycol t-butyl ether, propylene glycol phenyl ether, ethylene glycol methyl ether, diethylene glycol methyl ether, triethylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol ethyl ether, triethylene glycol ethyl ether, ethylene glycol n-propyl ether , Ethylene glycol n-butyl ether, diethylene glycol n-butyl ether, triethylene glycol n-butyl ether, ethylene glycol n-hexyl ether, diethylene glycol n-hexyl ether, ethylene glycol phenyl ether, and the like.

  Moreover, the aqueous pigment ink composition for inkjet recording of the present invention may further contain an organic solvent having a boiling point exceeding 285 ° C. as the organic solvent. The content of the organic solvent having a boiling point exceeding 285 ° C. is preferably in the range of 0 wt% or more and 1.0 wt% or less with respect to the aqueous pigment ink composition for ink jet recording. When the content of the organic solvent having a boiling point exceeding 285 ° C. exceeds 1.0% by weight, the coating properties (particularly chemical resistance) tend to deteriorate due to low temperature drying. Examples of the organic solvent having a boiling point higher than 285 ° C. include glycerin and polyethylene glycol.

(Other ingredients)
The aqueous pigment ink composition for ink jet recording of the present invention may further contain a surfactant in order to control the surface tension of the ink and improve the dispersion stability of the surfactant-dispersed pigment and emulsion resin. Examples of the surfactant include nonionic surfactants, acetylene glycol surfactants, and silicon surfactants. When a nonionic surfactant is added, it is possible to suppress the adhesion of solid content in the ink in the vicinity of the nozzle and improve the ejection stability. When an acetylene glycol surfactant is added, the dynamic surface tension can be reduced and the discharge stability can be improved. When a silicon-based surfactant is added, wettability with respect to a non-absorbent material can be improved.

  In addition, the aqueous pigment ink composition for ink jet recording of the present invention includes an antifoaming agent, a bactericidal agent, a moisturizing agent, a pH adjusting agent, a storage, which are conventionally used in the ink field for ink jet recording, if necessary. Additives such as stabilizers, anti-gelling agents, antiseptics, rust inhibitors can be added.

  The aqueous pigment ink composition for ink-jet recording of the present invention is prepared by mixing the surfactant-dispersed pigment, the emulsion resin, and the organic solvent, and then filtering coarse particles using a filter or the like. It is obtained by deaeration.

  The viscosity of the aqueous pigment ink composition for ink-jet recording of the present invention is preferably from 1.0 mPa · s to 10.0 mPa · s, more preferably from 2.5 mPa · s to 8.5 mPa · s at 25 ° C. When the viscosity is less than 1.0 mPa · s, image formation tends to be difficult, and when it exceeds 10.0 mPa · s, the ejection stability tends to be poor.

  Next, the image forming method of the present invention will be described.

  The image forming method of the present invention comprises an ejection step of ejecting the aqueous pigment ink composition for ink jet recording of the present invention from an ink jet head and adhering it to the recording medium, and an aqueous pigment ink composition for ink jet recording adhering to the recording medium. A heating step of heating the product to 40 ° C. or more and 80 ° C. or less. By the heating, the solvent in the ink composition attached to the recording medium is evaporated and drying is promoted to form an image. Thereby, it is excellent in water resistance, chemical resistance, and adhesiveness, and can form a high quality printed image.

  Examples of the recording medium include a base material made of an absorbent material such as paper, and a base material made of an ink non-absorbing material such as plastic or metal.

  Although the heating temperature in the said heating process should just be 40 degreeC or more, Preferably it is the range of 40 to 80 degreeC, More preferably, it is 45 to 60 degreeC. When the heating temperature exceeds 80 ° C., problems such as deformation of the recording medium may occur. In the present specification, in the heating process, when the water-based pigment ink composition for ink-jet recording is attached to the recording medium, the water-based pigment ink composition for ink-jet recording is applied to the recording medium when heat treatment is performed almost simultaneously with this. The case where the recording medium is preliminarily heated before being attached includes the case where the aqueous pigment ink composition for ink jet recording is heated together with the recording medium after being attached to the recording medium. The drying time is not particularly limited as long as the solvent in the aqueous pigment ink composition for ink jet recording can be evaporated.

  Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples. Further, unless otherwise indicated, in the following, “part” means “part by weight”. In the following, the “emulsion resin dispersion” means an aqueous solution containing the emulsion resin of the present invention.

Example 1
<Preparation of surfactant-dispersed pigment>
First, after mixing and stirring the following materials at the following ratios, using a paint shaker manufactured by Toyo Seiki Co., Ltd., dispersing zirconia beads having a diameter of 0.3 mm as a dispersion medium for 60 minutes to obtain a surfactant-dispersed pigment It was.
(1) Pigment (trade name “MCF # 1000” manufactured by Mitsubishi Chemical Corporation): 30.0 parts (2) Dispersant (polyoxyethylene alkyl ether sodium sulfate salt): 4.0 parts (3) Antifoaming agent ( Nissin Chemical Industry Co., Ltd., trade name “Surfinol 104E”): 0.2 parts (4) Water: 70.8 parts

<Preparation of water-based pigment ink for inkjet recording>
Next, the surfactant-dispersed pigment and the following materials were mixed and stirred at the following ratio to obtain an aqueous pigment ink for inkjet recording of Example 1. In Example 1, the content of the emulsion resin was 5% by weight, and the content of 2-pyrrolidone was 10% by weight.
(1) Surfactant-dispersed pigment (pigment concentration: 30%): 5.0 parts (2) Emulsion resin dispersion: Acrylic emulsion resin (manufactured by BASF, trade name “Joncrill PDX-7700”, glass transition Temperature: 80 ° C., resin component: 48%): 10.4 parts (resin component: 5% by weight)
(3) Silicone surfactant (manufactured by Big Chemie, trade name “BYK348”): 1.0 part (4) Preservative (manufactured by Arch Chemical Co., trade name “Proxel GXL (S)”): 0.2 part (5) Organic solvent having a boiling point of 285 ° C. or less: 2-pyrrolidone (manufactured by BASF): 10 parts (10% by weight)
(6) Water: 73.4 parts

(Example 2)
Aqueous pigment for inkjet recording of Example 2 in the same manner as in Example 1, except that the amount of the emulsion resin dispersion was changed to 20.8 parts and the amount of water was changed to 63.0 parts. An ink was prepared. In Example 2, the content of the emulsion resin was 10% by weight, and the content of 2-pyrrolidone was 10% by weight.

(Example 3)
Aqueous pigment for inkjet recording of Example 3 in the same manner as Example 1 except that the amount of the emulsion resin dispersion was changed to 41.7 parts and the amount of water was changed to 42.1 parts. An ink was prepared. In Example 3, the emulsion resin content was 20% by weight, and the 2-pyrrolidone content was 10% by weight.

Example 4
Aqueous pigment for inkjet recording of Example 4 in the same manner as in Example 1 except that the amount of the emulsion resin dispersion was changed to 62.5 parts and the amount of water was changed to 21.3 parts. An ink was prepared. In Example 4, the content of the emulsion resin was 30% by weight, and the content of 2-pyrrolidone was 10% by weight.

(Example 5)
Except that the amount of emulsion resin dispersion was changed to 41.7 parts, the amount of 2-pyrrolidone was changed to 20.0 parts, and the amount of water was changed to 32.1 parts In the same manner as in Example 1, an aqueous pigment ink for inkjet recording of Example 5 was produced. In Example 5, the content of the emulsion resin was 20% by weight, and the content of 2-pyrrolidone was 20% by weight.

(Example 6)
Except that the blending amount of the emulsion resin dispersion was changed to 62.5 parts, the blending amount of 2-pyrrolidone was changed to 20.0 parts, and the blending amount of water was changed to 11.3 parts. In the same manner as in Example 1, an aqueous pigment ink for inkjet recording of Example 6 was produced. In Example 6, the content of the emulsion resin was 30% by weight, and the content of 2-pyrrolidone was 20% by weight.

(Example 7)
Except that the blending amount of the emulsion resin dispersion was changed to 47.6 parts, the blending amount of 2-pyrrolidone was changed to 30.0 parts, and the blending amount of water was changed to 16.2 parts. In the same manner as in Example 1, an aqueous pigment ink for ink-jet recording of Example 7 was produced. In Example 7, the content of the emulsion resin was 20% by weight, and the content of 2-pyrrolidone was 30% by weight.

(Example 8)
As the emulsion resin dispersion, 44.4 parts of BASF's acrylic emulsion resin “Johncrill 532J” (glass transition temperature: 56 ° C., resin component: 45%) was used, and the blending amount of 2-pyrrolidone was 20 A water-based pigment ink for inkjet recording of Example 8 was prepared in the same manner as Example 1 except that the amount was changed to 0.0 parts and the amount of water was changed to 29.4 parts. In Example 8, the content of the emulsion resin was 20% by weight, and the content of 2-pyrrolidone was 20% by weight.

Example 9
The amount of emulsion resin dispersion was changed to 41.7 parts, the amount of 2-pyrrolidone was changed to 20.0 parts, the amount of water was changed to 31.1 parts, and the boiling point was 285. An aqueous pigment ink for ink-jet recording of Example 9 was produced in the same manner as Example 1 except that 1.0 part of glycerin, which is an organic solvent exceeding ℃, was further added. In Example 9, the content of the emulsion resin was 20% by weight, the content of 2-pyrrolidone was 20% by weight, and the content of glycerin was 1.0% by weight.

(Example 10)
Aqueous pigment ink for inkjet recording of Example 10 except that the amount of 2-pyrrolidone was changed to 40.0 parts and the amount of water was changed to 43.4 parts in the same manner as Example 1. Was made. In Example 10, the content of the emulsion resin was 5% by weight, and the content of 2-pyrrolidone was 40% by weight.

(Comparative Example 1)
Aqueous pigment for inkjet recording of Comparative Example 1 in the same manner as in Example 1, except that the amount of the emulsion resin dispersion was changed to 6.3 parts and the amount of water was changed to 77.6 parts. An ink was prepared. In Comparative Example 1, the content of the emulsion resin was 3% by weight, and the content of 2-pyrrolidone was 10% by weight.

(Comparative Example 2)
Aqueous pigment for inkjet recording of Comparative Example 2 in the same manner as in Example 1 except that the blending amount of the emulsion resin dispersion was changed to 72.9 parts and the blending amount of water was changed to 10.9 parts. An ink was prepared. In Comparative Example 2, the content of the emulsion resin was 35% by weight, and the content of 2-pyrrolidone was 10% by weight.

(Comparative Example 3)
Except that the amount of emulsion resin dispersion was changed to 41.7 parts, the amount of 2-pyrrolidone was changed to 5.0 parts, and the amount of water was changed to 47.1 parts. In the same manner as in Example 1, an aqueous pigment ink for inkjet recording of Comparative Example 3 was produced. In Comparative Example 3, the content of the emulsion resin was 20% by weight, and the content of 2-pyrrolidone was 5% by weight.

(Comparative Example 4)
Except that the blending amount of the emulsion resin dispersion was changed to 41.7 parts, the blending amount of 2-pyrrolidone was changed to 45.0 parts, and the blending amount of water was changed to 7.1 parts. In the same manner as in Example 1, an aqueous pigment ink for inkjet recording of Comparative Example 4 was produced. In Comparative Example 4, the content of the emulsion resin was 20% by weight, and the content of 2-pyrrolidone was 45% by weight.

(Comparative Example 5)
As the emulsion resin dispersion, 44.4 parts of BASF's acrylic emulsion resin “Jonkrill 775” (glass transition temperature: 37 ° C., resin component: 45%) was used, and the blending amount of 2-pyrrolidone was 20 A water-based pigment ink for inkjet recording of Comparative Example 5 was prepared in the same manner as in Example 1 except that the amount was changed to 0.0 parts and the amount of water was changed to 29.4 parts. In Comparative Example 5, the content of the emulsion resin was 20% by weight, and the content of 2-pyrrolidone was 20% by weight.

(Comparative Example 6)
The amount of emulsion resin dispersion was changed to 41.7 parts, the amount of 2-pyrrolidone was changed to 20.0 parts, the amount of water was changed to 30.1 parts, and the boiling point was 285. A water-based pigment ink for inkjet recording of Comparative Example 6 was prepared in the same manner as in Example 1 except that 2.0 parts of glycerin, which is an organic solvent having a temperature higher than 0 C, was further added. In Comparative Example 6, the content of the emulsion resin was 20% by weight, the content of 2-pyrrolidone was 20% by weight, and the content of glycerin was 2.0% by weight.

  For the aqueous pigment inks for inkjet recording of Examples 1 to 10 and Comparative Examples 1 to 6, the viscosity, drying property, chemical resistance, adhesion, ejection stability, and chromaticity were evaluated by the methods described below. It was.

(viscosity)
The viscosity (mPa · s) was measured using a “R100 viscometer” manufactured by Toki Sangyo Co., Ltd. under the conditions of 25 ° C. and cone rotation speed of 100 rpm.

(Drying)
The water-based pigment ink for ink-jet recording obtained in the above examples and comparative examples was dried on a polyethylene terephthalate film (untreated product) having a thickness of 75 μm by a bar coater (# 14) to a thickness of 1 to 2 μm after drying. A coating film was formed and dried at 60 ° C. for 3 minutes to prepare a sample for evaluation. A sample for evaluation was similarly prepared when the drying temperature was 90 ° C.

  Next, the coating surface of the sample for evaluation was rubbed with a cotton swab for 5 cm, and the ink adhesion state on the swab was observed.

  As a result, when the ink does not adhere to the cotton swab at all, the drying property is A (excellent). Immediately after preparing the evaluation sample, the ink adheres to such an extent that the ink is smudged with the cotton swab. After drying, the case where the ink does not adhere to the cotton swab is dryness: B (good), and the case where the ink adheres to the cotton swab after leaving the sample for evaluation for 5 minutes is dried: C (poor) It was evaluated.

(chemical resistance)
An evaluation sample was prepared in the same manner as in the case of the dryness evaluation, and the coating surface of the evaluation sample was rubbed 20 times with a cotton swab impregnated with an aqueous solution containing 50% ethanol, The state of peeling was observed.

  As a result, even when rubbing with a cotton swab, the coating film is not peeled off at all, and when the coating film has good film-forming properties and good adhesion to the substrate, the chemical resistance is A (excellent). Chemical resistance when observed: B (good), peeling is observed when the number of rubbing is 15 times or more, and the film forming property of the coating film and adhesion to the substrate are slightly insufficient : C (slightly bad), and when the number of rubbing is less than 15 and peeling is observed, and the film forming property of the coating film and the adhesion to the substrate are insufficient, chemical resistance: evaluated as D (defective) did.

(Adhesion)
A sample for evaluation was prepared in the same manner as in the case of the dryness evaluation, and a cross-cut peel test based on Japanese Industrial Standard (JIS) 5600-5-6-1999 was performed. As a result, when no peeling was observed for 100 test squares, the adhesion: A (good), when 1-5 peeling was observed, the adhesion: B (somewhat poor), and peeling The case where 6 or more places were seen was evaluated as adhesiveness: C (defect).

(Discharge stability)
Using the ink-jet printer “GELJET” manufactured by Ricoh, the aqueous pigment ink for ink-jet recording obtained in the above-mentioned examples and comparative examples is used as an A4 version of Xerox P paper with the MS word “Mincho” written by Microsoft as a standard style. At 100, 100 pages were continuously printed at a rate of 2000 characters / page, and the state of printing disorder was observed. Similarly, the printing disorder state was converted when 1000 pages were printed.

  As a result, ejection stability: A (excellent) when printing disturbance is less than 5 places, ejection stability: B (good) when printing disturbance is 5 places or more and less than 10 places, printing disturbance is 10 places or more and 50 places The case where the discharge stability was less than C was evaluated as discharge stability: C (slightly defective) and the case where there were 50 or more printing disturbances as discharge stability: D (defective).

(Chromaticity)
A sample for evaluation was prepared in the same manner as in the case of the dryness evaluation described above, and the hue was measured using a spectrocolorimetric densitometer (“X-Rite” manufactured by Nihon Hiraiso Equipment Co., Ltd.) * Asked. In the La * b * display system, the closer the value of L is to 0, the better the lightness of the black color. Here, the smaller the value of L, the better the chromaticity.

  Tables 1 and 2 show the evaluation results of the viscosity, drying property, chemical resistance, adhesion, ejection stability, and chromaticity of the aqueous pigment inks for inkjet recording of Examples 1 to 10 and Comparative Examples 1 to 6. It was. In addition, the glass transition temperature (Tg) and content of the emulsion resin contained in the aqueous pigment ink for inkjet recording and the content of the organic solvent are also shown.

  From Tables 1 and 2, the water-based pigment inks for inkjet recording of Examples 1 to 10 obtained almost satisfactory results in all of dryness, chemical resistance, adhesion, and ejection stability, and high quality. The print image of was able to be formed.

  On the other hand, in Comparative Example 1 in which the content of the emulsion resin was less than 5% by weight, the chemical resistance was lowered. In Comparative Example 2 in which the content of the emulsion resin was 30% by weight or more, the discharge stability was lowered. In Comparative Example 3 in which the content of the organic solvent having a boiling point of 285 ° C. or lower was less than 10% by weight, the discharge stability was lowered. In Comparative Example 4 in which the content of the organic solvent having a boiling point of 285 ° C. or lower exceeded 40% by weight, the drying property, chemical resistance, and adhesion were lowered, and the quality of the printed image was not good. In Comparative Example 5 in which the glass transition temperature of the emulsion resin was less than 60 ° C., the chemical resistance was lowered. In Comparative Example 6 in which the content of the organic solvent having a boiling point exceeding 285 ° C. exceeded 1.0% by weight, the chemical resistance was lowered.

  INDUSTRIAL APPLICABILITY The present invention can provide an aqueous pigment ink for ink jet recording that can be printed on a non-ink-absorbing material such as plastic and metal and that can realize high quality printed images.

Claims (5)

A water-based pigment ink composition for inkjet recording comprising a surfactant-dispersed pigment, an emulsion resin, water, and an organic solvent,
The glass transition temperature of the emulsion resin is 60 ° C. or higher,
The content of the emulsion resin is 5 wt% or more and less than 30 wt% with respect to the total amount of the aqueous pigment ink composition for inkjet recording,
The organic solvent contains an organic solvent having a boiling point of 285 ° C. or less in a range of 10 wt% to 40 wt% with respect to the total amount of the aqueous pigment ink composition for inkjet recording. Ink composition.   The aqueous pigment ink composition for ink jet recording according to claim 1, wherein the emulsion resin is an acrylic emulsion resin.   The aqueous pigment ink composition for ink jet recording according to claim 1 or 2, wherein the pigment concentration in the aqueous pigment ink composition for ink jet recording is 0.1 wt% or more and 20 wt% or less.   The organic solvent contains an organic solvent having a boiling point exceeding 285 ° C. in the range of 0 wt% or more and 1.0 wt% or less with respect to the total amount of the aqueous pigment ink composition for inkjet recording. 2. An aqueous pigment ink composition for ink jet recording according to item 1. An ejection step of ejecting the aqueous pigment ink composition for inkjet recording according to any one of claims 1 to 4 from an inkjet head and attaching it to a recording medium;
And a heating step of heating the water-based pigment ink composition for ink-jet recording attached to the recording medium to 40 ° C. or more and 80 ° C. or less.