JP6493670B2 - Non-aqueous inkjet ink composition - Google Patents

Description

  The present invention relates to a non-aqueous inkjet ink composition containing a non-volatile solvent as a main component.

  2. Description of the Related Art In recent years, inkjet recording apparatuses that record images and characters with fine ink droplets ejected from the nozzles of an inkjet recording head are rapidly spreading. As an ink used for recording an image or the like by such an ink jet recording apparatus, a water-based ink in which a coloring material (for example, a pigment or a dye) is dissolved or dispersed in a mixture of an organic solvent and water, or a coloring material is dissolved in an organic solvent. Various types such as dispersed non-aqueous inks are used.

  Among these inks, non-aqueous inks based on glycol ether solvents record excellent images with good drying and water resistance on recording media with low ink absorption (for example, vinyl chloride films). Widely used because it can. In addition, non-aqueous inks based on ester solvents and hydrocarbon solvents are also widely used because they are difficult to smell but have excellent drying properties. Solvents with higher boiling points are less volatile. It is also used for plain paper as a water-based ink.

  By the way, when recording on plain paper using a non-volatile ink with low volatility, the solvent on plain paper remains without evaporating and the remaining solvent component penetrates into the inside of plain paper, causing the back side of the recorded matter Therefore, there is a problem that the recorded portion can be seen through, and therefore, the back-through occurs or the remaining solvent component oozes out from the recorded portion.

  For example, Japanese Patent Application Laid-Open No. H10-228667 discloses a problem of showthrough or oil bleeding on plain paper by devising a solvent composition of a non-aqueous ink composition containing a non-volatile solvent as a main component. It is disclosed that the clogging problem can be solved simultaneously.

JP 2004002666 A

  However, in the non-aqueous ink composition described in Patent Document 1 described above, by improving the solvent composition, it is possible to improve the deterioration of reliability due to strike-through, oil bleeding, or standing on plain paper. When the pigment concentration is increased in order to obtain an image, nozzle clogging occurs, and there is a problem that ink ejection stability and storage stability are easily impaired.

  Therefore, some aspects according to the present invention can achieve at least a part of the above-described problems, thereby obtaining a sufficient optical density of an image in recording on plain paper and increasing the pigment density. However, the present invention provides a non-aqueous inkjet ink composition having good ejection stability and storage stability.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the non-aqueous inkjet ink composition according to the present invention is:
Containing a pigment, a non-aqueous solvent, and a surfactant,
The surfactant includes a siloxane surfactant having an HLB value of 1.0 or more and 7.0 or less.

  According to the non-aqueous inkjet ink composition of Application Example 1, a siloxane interface having an HLB value of 1.0 or more and 7.0 or less even when the pigment concentration is increased to obtain a sufficient optical density of an image. Since the activator (hereinafter also referred to as “specific siloxane surfactant”) is adsorbed on the pigment surface and the steric hindrance is increased, the dispersion stability of the pigment is improved. Therefore, the aggregation of the pigment in the ink is reduced and the thixotropy is lowered. When the thixotropy is lowered, the difference in viscosity due to the shear rate is reduced, so that the continuous ejection stability of the ink can be ensured even when the pigment concentration is increased. In addition, the inclusion of the specific siloxane surfactant increases the wettability of the pigment itself and facilitates affinity with a non-aqueous solvent, thereby increasing the dispersion stability of the pigment and improving long-term storage stability.

[Application Example 2]
In the non-aqueous inkjet ink composition of Application Example 1,
The non-aqueous solvent includes a non-polar organic solvent having a 50% distillation point of 280 ° C. or less and a polar organic solvent having a 50% distillation point of 300 ° C. or more,
The total content of the nonpolar organic solvent and the polar organic solvent in the nonaqueous solvent may be 60.0% by mass or more.

  According to the non-aqueous inkjet ink composition of Application Example 2, the solvent component quickly evaporates from the ink recorded on plain paper by containing a non-polar organic solvent having a 50% distillation point of 280 ° C. or less. , It is possible to effectively suppress the breakthrough and oil bleeding. Moreover, it can suppress that the drying property of an ink becomes high too much by containing the polar organic solvent whose 50% distillation point is 300 degreeC or more. Further, when the total content of these solvents is 60.0% by mass or more in the non-aqueous solvent, the ink drying property becomes appropriate, so that nozzle clogging in the vicinity of the nozzle is difficult to occur. it can.

[Application Example 3]
In the non-aqueous inkjet ink composition of Application Example 1 or Application Example 2,
In the measurement of shear viscosity with a rheometer at 20 ° C., the difference in shear viscosity between a shear rate of 20 [1 / s] and 500 [1 / s] is 0.60 [mPa · s] or less. it can.

  According to the non-aqueous inkjet ink composition of Application Example 3, since the difference in shear viscosity depending on the shear rate is sufficiently small, it can be easily solved by applying force to the aggregated pigment, and the ink ejection stability is further improved. .

[Application Example 4]
In the non-aqueous inkjet ink composition according to any one of Application Examples 1 to 3, the ratio of the pigment content to the specific siloxane surfactant content in the ink composition ([pigment content ] / [Content of specific siloxane-based surfactant]) can be 0.1 or more and less than 3.0.

  When the content ratio of the pigment and the specific siloxane surfactant in the ink composition is within the above range, the specific siloxane surfactant is sufficiently adsorbed on the surface of the pigment. In addition, the storage stability is further improved.

[Application Example 5]
In the non-aqueous inkjet ink composition of any one of Application Examples 1 to 4, the pigment content is 5.0% by mass or more and 15.0% by mass or less based on the total mass of the ink composition. Can be.

  According to the non-aqueous inkjet ink composition of Application Example 5, even when the pigment concentration is higher than the normal concentration, continuous discharge stability is improved by the action of the specific siloxane surfactant, and long-term storage stability is improved. The property is also good. Further, when the pigment concentration is within the above range, a sufficient optical density of the image can be obtained.

[Application Example 6]
In the non-aqueous inkjet ink composition according to any one of Application Examples 1 to 5, the content of the siloxane surfactant is 1.0% by mass or more and 10.0% by mass or more based on the total mass of the ink composition. It can be up to mass%.

  According to the non-aqueous inkjet ink composition of Application Example 6, the difference in shear viscosity due to the shear rate can be sufficiently reduced among the above effects by containing a predetermined amount of the specific siloxane surfactant. As a result, when force is applied to the agglomerated pigment, it is easily released, and the ink ejection stability can be further improved.

[Application Example 7]
In the non-aqueous inkjet ink composition of any one of Application Examples 1 to 6, the siloxane surfactant may be an organically modified polysiloxane surfactant.

  According to the non-aqueous inkjet ink composition of Application Example 7, by using an organically modified polysiloxane surfactant as the specific siloxane surfactant, the steric hindrance becomes larger when adsorbed on the pigment surface. The dispersion stability of the pigment is improved. In addition, the wettability of the pigment itself with the non-aqueous solvent is increased, and the pigment itself becomes more compatible with the non-aqueous solvent. Therefore, the dispersion stability of the pigment is increased and the long-term storage stability is improved.

[Application Example 8]
In the non-aqueous inkjet ink composition according to any one of Application Examples 2 to 7, the non-polar organic solvent is at least selected from the group consisting of aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons. One can be included.

[Application Example 9]
In the non-aqueous inkjet ink composition according to any one of Application Example 2 to Application Example 8, as the polar organic solvent, soybean oil methyl, soybean oil isobutyl, methyl oleate, ethyl oleate, isostearyl alcohol, oleyl alcohol, It may contain at least one selected from the group consisting of palmitic acid, isostearic acid, isoarachidic acid, isohexacic acid, isopropyl isostearate, methyl linoleate, isobutyl linoleate and isobutyl tall oil.

  Several embodiments of the present invention will be described below. Embodiment described below demonstrates an example of this invention. The present invention is not limited to the following embodiments, and includes various modifications that are implemented without departing from the scope of the present invention. Note that not all of the configurations described below are essential configurations of the present invention.

  In the present invention, “image” indicates a pattern formed from a group of dots, and the pattern includes a print pattern, a pattern such as a picture or a pattern, and a solid pattern.

  In the present invention, the “non-aqueous (inkjet) ink composition” refers to an ink having an organic solvent as a main solvent and not water as a main solvent. Preferably, the water content in the ink composition is 3% by mass or less, more preferably 1% by mass or less, still more preferably less than 0.05% by mass, and still more preferably less than 0.01% by mass. More preferably, it means less than 0.005% by mass, and most preferably less than 0.001% by mass. Or it is good also as an ink composition which does not contain water substantially. "Substantially not containing" means not intentionally containing, and does not exclude impurities and unavoidable cases.

1. Non-aqueous ink-jet ink composition The non-aqueous ink-jet ink composition according to this embodiment (also simply referred to as “ink composition” in the present specification) contains a pigment, a non-aqueous solvent, and a surfactant. The surfactant includes a siloxane-based surfactant having an HLB value of 1.0 or more and 7.0 or less. Hereinafter, components included in the ink composition according to the present embodiment and components that may be included will be described in detail.

1.1. Pigment As the pigment used in the present embodiment, either an inorganic pigment or an organic pigment can be used.

  Examples of organic pigments include azo pigments (for example, azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, Thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye lakes (for example, basic dye type lakes, acid dye type lakes, etc.), nitro pigments, nitroso pigments, aniline black, daylight fluorescent pigments and the like. Examples of inorganic pigments include carbon black, titanium dioxide, silica, and alumina. These pigments may be used alone or in combination of two or more.

In particular, as pigments for black ink, carbon blacks such as furnace black, lamp black, acetylene black and channel black; metals or metal oxides such as copper, iron and titanium oxide; organic pigments such as orthonitroaniline black Can be mentioned. In that the optical density of the higher image obtained, dibutyl phthalate measured according to JIS K6221 (DBP) absorption of 80cm ³ / 100g~140cm ³ / 100g, and a nitrogen adsorption measured according to JIS K6217 a specific surface area of 100m ² / g~200m ² / g carbon black pigment is preferred.

  The content of the pigment in the ink composition according to this embodiment can be appropriately set as desired, and is not particularly limited. However, the lower limit is an ink from the viewpoint of obtaining a sufficient optical density of an image. Preferably it is 5.0 mass% or more with respect to the total mass of a composition, More preferably, it is 6.0 mass% or more, Most preferably, it is 7.0 mass% or more. The upper limit is preferably 15.0% by mass or less, more preferably 14.0% by mass or less, and particularly preferably 13% by mass with respect to the total mass of the ink composition from the viewpoint of ensuring continuous printing stability of the ink. 0.0 mass% or less.

The average particle diameter of the pigment is preferably 300 nm or less, more preferably 150 nm or less, and particularly preferably 100 nm or less from the viewpoint of continuous ejection stability and storage stability of the ink. Here, the average particle diameter of the pigment can be measured by, for example, a dynamic light scattering particle size distribution measuring device “LB-500” (manufactured by Horiba, Ltd.).

  In addition, a pigment dispersant may be added in order to improve the dispersion stability of the pigment in the ink composition. As the pigment dispersant, those commonly used in non-aqueous ink compositions can be used. For example, a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a high molecular weight polycarboxylic acid, and the like. Salt of acid, salt of long-chain polyaminoamide and polar acid ester, high molecular weight unsaturated acid ester, polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic active agent, naphthalenesulfonic acid formalin condensate Salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonylphenyl ether, polyester polyamine, stearylamine acetate, and the like can be used.

  Examples of commercially available pigment dispersants include polyester polymer compounds such as Hinoact KF1-M, T-6000, T-7000, T-8000, T-8350P, and T-8000E (all manufactured by Takefu Fine Chemical Co., Ltd.). Solsperse 11200, 13940, 18000, 20000, 24000, 28000, 32000, 32500, 33500, 34000, 35200, 37500 (all manufactured by LUBRIZOL), Disperbyk-161, 162, 163, 164, 166, 180, 190, 191 , 192, 2091, 2095 (all manufactured by Big Chemie Japan), Floren DOPA-17, 22, 33, G-700 (all manufactured by Kyoeisha Chemical Co., Ltd.), Ajisper PB821, PB711 (all tastes) Made prime Co., Ltd.), LP4010, LP4050, LP4055, POLYMER400,401,402,403,450,451,453 (all manufactured by EFKA Chemicals Co., Ltd.), and the like. The content ratio of the pigment dispersant can be appropriately selected according to the pigment to be used, but is preferably 5 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the pigment in the ink composition. Preferably they are 30 to 120 mass parts.

1.2. Non-aqueous solvent The ink composition according to this embodiment contains a non-aqueous solvent. Non-aqueous solvents include non-polar organic solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons; polar organic solvents such as ester solvents, alcohol-based solvents, ether-based solvents, and higher fatty acids. .

  Examples of the aliphatic hydrocarbon include paraffin and isoparaffin. Examples of the alicyclic hydrocarbon include cyclohexane, cyclooctane, cyclodecane and the like. Examples of the aromatic hydrocarbon include benzene, toluene, xylene, naphthalene, and tetralin. As such a non-polar organic solvent, commercially available products may be used, such as IP solvent 1016, IP solvent 1620, IP Clean LX (all trade names made by Idemitsu Kosan Co., Ltd.), Isopar G, Isopar. L, Isopar H, Isopar M, Exxsol D40, Exxsol D80, Exxsol D100, Exxsol D130, Exxsol D140 (all are trade names manufactured by Exxon), NS Clean 100, NS Clean 110, NS Clean 200, NS Clean 220 ( All of the above are trade names of JX Nippon Oil & Energy Corporation, Naphthezol 160, Naphthezol 200, Naphthezol 220, AF-4, AF-6, AF-7 (all of these are trade names of JX Nippon Mining & Energy Corporation) etc Aromatic hydrocarbon solvents and alicyclic hydrocarbon solvents such as Solvesso 200 (trade name manufactured by Exxon), Nisseki Cleansol G (alkylbenzene, manufactured by JX Nippon Oil & Energy Corporation), etc. Is mentioned.

Examples of ester solvents include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, isopentyl acetate, sec-butyl acetate, amyl acetate, methoxybutyl acetate, methyl lactate, ethyl lactate, lactic acid Butyl, methyl caprylate, methyl laurate, isopropyl laurate, hexyl laurate, isopropyl myristate, isopropyl palmitate, isooctyl palmitate, methyl oleate, ethyl oleate, isopropyl oleate, butyl oleate, methyl linoleate, Isobutyl linoleate, ethyl linoleate, isobutyl linoleate, isopropyl isostearate, soybean oil methyl, soybean oil isobutyl, methyl tall oil, tall oil isobutyl, diisopropyl adipate, sebacin Diisopropyl, diethyl sebacate, propylene glycol monocaprate, trimethylolpropane tri-2-ethylhexanoate, glyceryl tri-2-ethylhexanoate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene Examples include glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate.

  Examples of the alcohol solvent include methanol, ethanol, isopropanol, 1-propanol, 1-butanol, 2-butanol, 3-pentanol, 2-methyl-1-butanol, 2-methyl-2-butanol, isoamyl alcohol, 3-methyl-2-butanol, 3-methoxy-3-methyl-1-butanol, 4-methyl-2-pentanol, allyl alcohol, 1-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, isomyristyl Examples include alcohol, isopalmityl alcohol, isostearyl alcohol, oleyl alcohol and the like.

  Examples of ether solvents include diethyl glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, propylene glycol dibutyl ether and the like.

  Examples of higher fatty acids include isoarachidic acid, isohexacic acid, isononanoic acid, isomyristic acid, hexadecanoic acid, isopalmitic acid, oleic acid, and isostearic acid.

  These non-aqueous solvents may be used alone or in combination of two or more.

  The non-aqueous solvent used in the present embodiment includes a non-polar organic solvent having a 50% distilling point of 280 ° C. or lower and a polar organic solvent having a 50% distilling point of 300 ° C. or higher, The total content of the nonpolar organic solvent and the polar organic solvent is preferably 60.0% by mass or more. By containing a nonpolar organic solvent having a 50% distilling point of 280 ° C. or lower, the solvent component quickly evaporates from the ink composition recorded on plain paper, so that it is possible to effectively suppress back-through and oil bleeding. . Moreover, it can suppress that the drying property of an ink becomes high too much by containing the polar organic solvent whose 50% distillation point is 300 degreeC or more. In addition, since the total content of these solvents is 60.0% by mass or more in the non-aqueous solvent, the ink drying property becomes appropriate (that is, the ink can be prevented from being dried too much) in the vicinity of the nozzle. It is possible to prevent nozzle clogging.

  The 50% distillation point can be measured according to JIS K0066 “Method for Distillation Test of Chemical Products” and means the temperature at which 50% by weight of the solvent is volatilized. In the non-aqueous solvent, if the non-polar organic solvent having a 50% distilling point of 280 ° C. or less and the polar organic solvent having a 50% distilling point of 300 ° C. or more are combined and contained 60.0% by mass or more, A nonpolar organic solvent having a 50% distillation point exceeding 280 ° C or a polar organic solvent having a 50% distillation point less than 300 ° C may be contained.

The nonpolar organic solvent having a 50% distillation point of 280 ° C. or lower is 10% relative to the total mass of the nonaqueous solvent.
. The content is preferably 0% by mass or more, and more preferably 20.0% by mass or more. When the content of the nonpolar organic solvent having a 50% distilling point of 280 ° C. or lower is in the above range, the solvent component quickly evaporates from the ink composition recorded on plain paper. It can be effectively suppressed.

  The polar organic solvent having a 50% distillation point of 300 ° C. or higher preferably contains 10.0% by mass or more, more preferably 15.0% by mass or more, based on the total mass of the non-aqueous solvent. preferable. When the content ratio of the polar organic solvent having a 50% distillation point of 300 ° C. or higher is within the above range, the ink can be prevented from being dried excessively, so that the nozzle can be hardly clogged.

  Examples of polar organic solvents having a 50% distillation point of 300 ° C. or higher include, for example, soybean oil methyl, soybean oil isobutyl, methyl oleate, ethyl oleate, isostearyl alcohol, oleyl alcohol, isopalmitic acid, isostearic acid, isoarachidic acid, Examples include isohexaconic acid, isopropyl isostearate, methyl linoleate, isobutyl linoleate, and isobutyl tall oil.

  The content of the non-aqueous solvent in the non-aqueous ink-jet ink composition according to the present embodiment is not particularly limited, but is preferably 50.0% by mass or more based on the total mass of the ink composition. Preferably it is 60.0 mass% or more, Most preferably, it is 70.0 mass% or more.

1.3. Specific siloxane-based surfactant The non-aqueous inkjet ink composition according to the present embodiment contains a siloxane-based surfactant (specific siloxane-based surfactant) having an HLB value of 1.0 or more and 7.0 or less. By containing a specific siloxane-based surfactant, even if the pigment concentration is increased in order to obtain a sufficient optical density of the image, the specific siloxane-based surfactant is adsorbed on the pigment surface and the steric hindrance is large. Therefore, the dispersion stability of the pigment is improved. Therefore, the aggregation of the pigment in the ink composition is reduced and the thixotropy is lowered. And if thixotropy falls, the viscosity difference by a shear rate will also become small. This is because it is easy to move when force is applied to the agglomerated pigment, and the agglomerated pigment can be easily solved even with a small force, so the viscosity difference is considered to be small. The fact that agglomerated pigments are easily disengaged even with a small force also means that the ink can move easily, which leads to ejection stability. That is, since ink can be ejected with a small force, it is possible to ensure continuous ejection stability of the ink even when the pigment concentration is increased. In addition, the inclusion of the specific siloxane-based surfactant increases the wettability of the pigment itself and facilitates affinity with a non-aqueous solvent, thereby increasing the dispersion stability of the pigment and improving long-term storage stability.

Here, the HLB value in the present invention is a value for evaluating the hydrophilicity of a compound proposed by Davis et al., For example, the document “J. Davies and EK Rideal,“ Interface Phenomena ”2nd ed. Academic Press. , New York 1963 ”, which is a numerical value obtained by the Davis method and calculated by the following equation (1).
HLB value = 7 + Σ [1] + Σ [2] (1)
(In the above formula, [1] represents the number of hydrophilic groups and [2] represents the number of hydrophobic groups.)

The specific siloxane surfactant used in the present embodiment has an HLB value calculated by the Davis method in the range of 1.0 or more and 7.0 or less, and the lower limit value of the HLB value is preferably 2.0 or more. More preferably, it is 3.0 or more. When the HLB value is within the above range, the specific siloxane-based surfactant is likely to be adsorbed on the surface of the pigment (particularly oil-soluble pigment), so that the dispersion stability of the pigment is improved. As a result, the effects as described above are easily obtained in the ink composition, and the continuous ejection stability and long-term storage stability of the ink are improved. When a siloxane-based surfactant having an HLB value exceeding 7.0 is added, reverse micelles with the hydrophilic group portion centered in a non-aqueous solvent are formed preferentially rather than adsorbing on the surface of the pigment. As a result, it is difficult to obtain the effects described above in the ink composition, and it is difficult to improve the continuous ejection stability and long-term storage stability of the ink.

  The specific siloxane-based surfactant is not particularly limited as long as the HLB value is in the range of 1.0 or more and 7.0 or less, but is an organically modified polysiloxane surfactant represented by the following general formula (2). Preferably there is. By using the organically modified polysiloxane surfactant, the steric hindrance becomes larger when adsorbed on the pigment surface, and the dispersion stability of the pigment is improved. In addition, the wettability of the pigment itself with the non-aqueous solvent is increased, and the pigment itself becomes more compatible with the non-aqueous solvent. Therefore, the dispersion stability of the pigment is increased and the long-term storage stability is improved.

In the above formula (1), R ¹ , R ² and R ³ each independently represents an organic group. n is an integer of 1-100. As the organically modified polysiloxane surfactant, one end organic modified type in which either R ¹ or R ² is substituted with an organic group, or both ends organic modified in which both R ¹ and R ² are substituted with an organic group Type, a side chain organic modified type in which R ³ is substituted with an organic group, and a mixed organic modified type that is a mixed type thereof.

Examples of the organic group for R ¹ , R ² and R ³ include a hydrogen atom, an alkyl group, an aralkyl group, an amino group, an epoxy group, a carbinol group, an acryloyl group, a methacryloyl group, a polyether group, a mercapto group, and a carboxyl group. , Hydroxyl group, phenyl group, fatty acid ester, fatty acid amide and the like. These organic groups may have a substituent. Among these organic groups, the specific siloxane surfactant in which R ¹ and R ² are alkyl groups having 1 to 4 carbon atoms (preferably methyl groups) and R ³ is a polyether group is used to disperse pigments. It is preferable at the point which can improve a property effectively.

  Specific examples of such specific siloxane surfactants include KF-352A (HLB value: 7), KF-945 (HLB value: 4), KF-6020 (HLB value: 4), KF-6012 (HLB). Value: 7), KF-6015 (HLB value: 4.5), KF-6017 (HLB value: 5), XX-22-4515 (HLB value: 5) (manufactured by Shin-Etsu Chemical Co., Ltd.) BY11-030 (HLB value: 3), BY22-008M (HLB value: 2), BY-25-337 (HLB value: 3) (manufactured by Toray Dow Corning Co., Ltd.), and the like. The specific siloxane surfactant may be used alone or in combination of two or more.

The content of the specific siloxane-based surfactant in the non-aqueous inkjet ink composition according to this embodiment is not particularly limited, but the lower limit is an ink composition from the viewpoint of improving the dispersion stability of the pigment. Preferably it is 1.0 mass% or more with respect to the total mass of a thing, More preferably, it is 2.0 mass% or more, Most preferably, it is 3.0 mass% or more. The upper limit is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, and particularly preferably 6% by mass with respect to the total mass of the ink composition, from the viewpoint of ensuring continuous printing stability of the ink. 0.0 mass% or less. If the content of the specific siloxane surfactant is within the above range, the difference in shear viscosity depending on the shear rate will be sufficiently small, so it can be easily solved by applying force to the agglomerated pigment, and ink ejection stability Can be further improved. When the upper limit of the content of the specific siloxane-based surfactant exceeds 10.0% by mass, a molecular aggregate (for example, micelle) of the specific siloxane-based surfactant is formed in the ink composition, and the particles are like particles. In some cases, defective discharge may occur due to proper behavior.

  The content of the specific siloxane surfactant contained in the ink composition is preferably adjusted as appropriate according to the content of the pigment contained in the ink composition. Specifically, the ratio of the pigment content and the specific siloxane surfactant content in the ink composition ([pigment content] / [specific siloxane surfactant content]) is preferable. Is 0.1 or more and less than 3.0, more preferably 0.5 or more and 2.8 or less, and particularly preferably 1.0 or more and 2.5 or less. When the content ratio of the pigment and the specific siloxane surfactant in the ink composition is within the above range, the specific siloxane surfactant can be sufficiently adsorbed on the surface of the pigment, and an excess of the specific siloxane surfactant can be obtained. Since problems due to the surfactant (discharge failure due to formation of molecular aggregates) can be suppressed, the discharge stability and storage stability of the ink composition are further improved.

1.4. Other Components Components other than those described above may be further added to the ink composition according to the present embodiment. Examples of such components include resins, chelating agents, preservatives, viscosity modifiers, dissolution aids, antioxidants, and antifungal agents.

1.4.1. Resin The ink composition according to this embodiment may contain a resin (hereinafter, also referred to as “fixing resin”) for fixing the above-described pigment to a recording medium.

  As fixing resin, acrylic resin, styrene acrylic resin, rosin modified resin, phenol resin, terpene resin, polyester resin, polyamide resin, epoxy resin, vinyl acetate resin, vinyl chloride resin, cellulose acetate butyrate and other fiber resins, Examples include vinyl toluene-α-methylstyrene copolymer resin. Among these, at least one resin selected from the group consisting of acrylic resins and vinyl chloride resins is preferable. By containing these fixing resins, the fixing property to the recording medium can be improved and the abrasion resistance is also improved.

  The solid content of the fixing resin in the ink composition according to this embodiment is preferably 0.05% by mass or more and 15.0% by mass or less, more preferably 0.1% by mass or more and 10.0% by mass or less. is there. When the content of the fixing resin is within the above range, excellent fixability to the recording medium can be obtained.

<Acrylic resin>
As the acrylic resin, a copolymer made of a conventionally known polymerizable monomer can be used. Examples of the polymerizable monomer include acrylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, Methacrylic acid esters such as n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate; acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, mono maleic acid Carboxy group-containing monomers such as n-butyl, mono-n-butyl fumarate, mono-n-butyl itaconate, hydroxyl group-containing (meth) acrylic acid esters, amide group-containing monomers, glycidyl group-containing monomers, cyano group-containing monomers Hydroxyl-containing allyl compounds may be used tertiary amino group-containing monomer, an alkoxysilyl group-containing monomers alone or in combination with.

  Commercially available products may be used as the acrylic resin, for example, Acrypet MF (trade name, manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin), Sumipex LG (trade name, manufactured by Sumitomo Chemical Co., Ltd., acrylic resin), Paraloid B series, etc. (Trade name, manufactured by Rohm and Haas, acrylic resin), Parapet G-1000P (trade name, manufactured by Kuraray Co., Ltd.). In the present invention, (meth) acrylic acid means both acrylic acid and methacrylic acid, and (meth) acrylate means both acrylate and methacrylate.

<Vinyl chloride resin>
Examples of the vinyl chloride resin include copolymers of vinyl chloride and other monomers such as vinyl acetate, vinylidene chloride, acrylic acid, maleic acid, vinyl alcohol, etc. Among these, vinyl chloride and vinyl acetate can be used. A copolymer containing a derived structural unit (hereinafter also referred to as “vinyl chloride copolymer”) is preferred, and a vinyl acetate copolymer having a glass transition temperature of 60 to 80 ° C. is more preferred.

  The vinyl chloride / vinyl chloride copolymer can be obtained by a conventional method, for example, by suspension polymerization. Specifically, water, a dispersant, and a polymerization initiator are charged into the polymerization vessel and degassed, and then vinyl chloride and vinyl acetate are injected to perform suspension polymerization, or a portion of vinyl chloride and vinyl acetate are injected. Thus, the reaction can be started and suspension polymerization can be performed while the remaining vinyl chloride is injected during the reaction.

  The vinyl chloride / vinegar copolymer preferably contains 70 to 90% by mass of vinyl chloride units as its constitution. If it is the said range, since it melt | dissolves stably in an ink composition, it is excellent in long-term storage stability. Furthermore, the ejection stability is excellent, and excellent fixability to the recording medium can be obtained.

  Further, the vinyl chloride / vinyl acetate copolymer may be provided with other structural units as necessary together with the vinyl chloride unit and the vinyl acetate unit, such as a carboxylic acid unit, a vinyl alcohol unit, and a hydroxyalkyl acrylate unit. Of these, vinyl alcohol units are particularly preferred. It can be obtained by using monomers corresponding to the aforementioned units. Specific examples of monomers that give carboxylic acid units include maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, acrylic acid, and methacrylic acid. Specific examples of the monomer that gives a hydroxyalkyl acrylate unit include, for example, hydroxyethyl (meth) acrylate, hydroxyethyl vinyl ether, and the like. The content of these monomers is not limited as long as the effects of the present invention are not impaired. For example, the monomers can be copolymerized in a range of 15% by mass or less of the total amount of monomers.

  In addition, a commercially available vinyl chloride copolymer may be used. For example, sorbine CN, solvin CNL, solvin C5R, solvin TA5R, sorbine CL, sorbine CLL (manufactured by Nissin Chemical Industry Co., Ltd.) Etc.

  Although the average degree of polymerization of these resins is not particularly limited, it is preferably 150 to 1100, more preferably 200 to 750. When the average degree of polymerization of these resins is in the above range, the resin is stably dissolved in the ink composition according to the present embodiment, and thus has excellent long-term storage stability. Furthermore, the ejection stability is excellent, and excellent fixability to the recording medium can be obtained. The average degree of polymerization of these resins is calculated from the specific viscosity measured, and can be determined according to the method for calculating the average degree of polymerization described in “JIS K6720-2”.

  Moreover, the number average molecular weight of these resins is not particularly limited, but is preferably 10,000 to 50,000, and more preferably 12,000 to 42,000. The number average molecular weight can be measured by GPC and can be obtained as a relative value in terms of polystyrene.

1.4.2. Other In addition to the above components, the ink composition according to the present embodiment includes a chelating agent such as ethylenediaminetetraacetate (EDTA), an antiseptic, a viscosity modifier, a dissolution aid, an antioxidant, and an antifungal agent. A substance for imparting a predetermined performance can be contained.

1.5. Physical Properties The ink composition according to the present embodiment has a viscosity (viscosity at 20 ° C.) of 2.0 mPa · s or more and 20.0 mPa · s or less by adjusting the composition and blending, for example, from the viewpoint of use as an inkjet ink. It is preferable to be 3.0 mPa · s or more and 15.0 mPa · s or less. As a result, the ejection stability (e.g., ejection volume stability, droplet flight characteristics) of the inkjet ink, ejection response (response speed, high frequency compatibility (frequency characteristics), etc.), etc. shall be excellent. Can do. In addition, the viscosity of the ink for inkjet can be calculated | required by the measurement based on JISZ8809 using a vibration viscometer.

  Further, in the shear viscosity measurement of the ink composition according to the present embodiment using a rheometer at 20 ° C., the difference in shear viscosity when the shear rate is 20 [1 / s] and 500 [1 / s] is 0. It is preferably 60 [mPa · s] or less, more preferably 0.50 [mPa · s] or less, still more preferably 0.40 [mPa · s] or less, and 0.30 [mPa · s]. -S] is particularly preferable. If the ink composition has a difference in shear viscosity between the shear rate of 20 [1 / s] and 500 [1 / s] within the above range, the difference in viscosity due to the shear rate is sufficiently small, and the ink composition is aggregated. Ink discharge stability is further improved because it can be easily solved by applying a small force to the pigment.

Here, as a method for measuring the shear viscosity, for example, a cone plate (diameter 75 mm, angle 1 °) mounted on a viscoelasticity measuring device (manufactured by Anton Paar, device name “Physica MCR301”) is filled at 20 ° C. The method of measuring the shear viscosity with respect to the shear rate (10-1000 s < ^-1 >) in is mentioned.

1.6. Use The non-aqueous inkjet ink composition according to the present embodiment is an ink used for inkjet recording. The ink jet recording apparatus is not particularly limited, but a drop-on-demand ink jet recording apparatus is preferable. The drop-on-demand ink jet recording apparatus employs a piezoelectric element recording method in which recording is performed using a piezoelectric element disposed in a recording head, and heat generated by a heater of a heating resistance element disposed in the recording head. There are methods that employ a thermal jet recording method in which recording is performed using energy, and any recording method can be employed. Further, since the non-aqueous inkjet ink composition according to the present embodiment has an advantage that it is inactive with respect to the discharge nozzle surface subjected to the ink repellent treatment, for example, for inkjet recording having the discharge nozzle surface subjected to the ink repellent treatment. It is also advantageous for an ink jet recording method for discharging from a head.

The application of the non-aqueous inkjet ink composition according to the present embodiment is not particularly limited, but a sufficient optical density of an image can be obtained in recording on plain paper, and ejection stability and storage stability can be obtained. Since it is good, it is suitable as an ink for a high-speed ink jet printer using plain paper.

2. EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited only to these examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

2.1. Preparation of black pigment dispersion <Black pigment dispersion 1>
13 parts by mass of soybean oil methyl, 15 parts by mass of soybean oil isobutyl, 10 parts by mass of ethyl oleate, 10 parts by mass of isostearyl alcohol, 17 parts by mass of hydrocarbon solvent (manufactured by JX Nippon Mining & Energy Corporation, AF-4), 15 parts by mass of a hydrocarbon solvent (manufactured by JX Nippon Oil & Energy Corporation, AF-6) is mixed, and 5 parts by mass of Solsperse 13940 (trade name, manufactured by Lubrizol) is dissolved as a dispersant. 15 parts by mass of Mitsubishi Chemical Corporation, MA-100) was added and premixed. Then, it disperse | distributed in the residence time about 20 minutes with the bead mill, and the black pigment dispersion liquid 1 was obtained.

It was 100 cm < ³ > / 100g when dibutyl phthalate (DBP) absorption amount was measured according to JISK6221 about said carbon black (the Mitsubishi Chemical Corporation make, MA-100). Moreover, it was 110 m < ² > / g when the nitrogen adsorption specific surface area was measured according to JISK6217.

<Black pigment dispersion 2>
10 parts by mass of soybean oil methyl, 13 parts by mass of soybean oil isobutyl, 10 parts by mass of ethyl oleate, 10 parts by mass of isostearyl alcohol, 17 parts by mass of hydrocarbon solvent (manufactured by JX Nippon Oil & Energy Corporation, AF-4), 15 parts by mass of a hydrocarbon solvent (manufactured by JX Nippon Mining & Energy Co., Ltd., AF-6) is mixed, and 5 parts by mass of Solsperse 13940 (trade name, manufactured by Lubrizol Co., Ltd.) is dissolved as a dispersant. (Tokai Carbon Co., Ltd., SAF-HS) 20 parts by mass was added and premixed. Thereafter, the mixture was dispersed in a bead mill with a residence time of about 20 minutes to obtain a black pigment dispersion 2.

The above-mentioned carbon black (Tokai Carbon Co., Ltd., SAF-HS) a month, was measured dibutyl phthalate (DBP) absorption in accordance with JIS ^K6221, was 130cm 3 / 100g. Moreover, it was 142 m < ² > / g when the nitrogen adsorption specific surface area was measured according to JISK6217.

<Cyan pigment dispersion>
13 parts by mass of soybean oil methyl, 15 parts by mass of soybean oil isobutyl, 10 parts by mass of ethyl oleate, 10 parts by mass of isostearyl alcohol, 17 parts by mass of hydrocarbon solvent (manufactured by JX Nippon Mining & Energy Corporation, AF-4), 15 parts by mass of a hydrocarbon solvent (manufactured by JX Nippon Oil & Energy Corporation, AF-6) is mixed, and 5 parts by mass of Solsperse 13940 (trade name, manufactured by Lubrizol) is dissolved as a dispersant. I. 15 parts by mass of Pigment Blue 15: 3 was added and premixed. Thereafter, the mixture was dispersed in a bead mill with a residence time of about 20 minutes to obtain a cyan pigment dispersion.

2.2. Preparation of Ink Composition Any one of the pigment dispersions prepared above so as to have the pigment concentrations shown in Table 1 was weighed in a beaker, and then a hydrocarbon solvent (manufactured by JX Nippon Mining & Energy Corporation, AF -4), an ester solvent (trade name “EXEPEARL M-OL”, methyl oleate, manufactured by Kao Corporation) and the surfactants listed in Table 1 were further added to each ink, and sufficiently mixed and stirred. A composition was prepared.

<Measurement of shear viscosity difference (Δ shear viscosity difference)>
Each ink composition obtained above was filled into a cone plate (diameter 75 mm, angle 1 °) attached to a viscoelasticity measuring device (manufactured by Anton Paar, device name “Physica MCR301”) at 20 ° C. The shear viscosity with respect to the shear rate (10 to 1000 s ⁻¹ ) was measured. Then, the shear viscosity at a shear rate of 20 [1 / s] and the shear viscosity at a shear rate of 500 [1 / s] were determined, and the difference was evaluated.

2.3. Ink composition evaluation test <Continuous printing stability>
Using an inkjet printer “PX-B700” manufactured by Seiko Epson Corporation, 30 solid patterns having a recording resolution of 600 × 600 dpi were recorded continuously on XeroxP paper A4 size at room temperature. The continuous printing stability was evaluated based on the number of the recorded materials out of the 30 recorded materials. The evaluation criteria are as follows.
◯: The number of recorded material in which missing has occurred is less than 10.
(Triangle | delta): The number of sheets of the printed matter in which omission has occurred is 10 or more and less than 20.
X: The number of recorded matter in which missing has occurred is 20 or more.

<OD>
Using an inkjet printer “PX-B700” manufactured by Seiko Epson Corporation, a solid pattern with a recording resolution of 600 × 600 dpi was recorded on XeroxP paper A4 size at room temperature. After the recorded matter was dried, the OD of the recorded matter was measured and evaluated with a Spectrolino (manufactured by Gretag Macbeth). The evaluation criteria are as follows.
○: 1.1 or more.
Δ: More than 1.0 and less than 1.1.
X: Less than 1.0.

<Storage stability>
The ink composition prepared above was placed in a sealed container and allowed to stand at 70 ° C. for 9 days. The viscosity of the ink composition immediately after preparation and the viscosity of the ink composition after standing were measured by a method based on JIS Z8809 using a vibration viscometer, and the rate of change was determined. The evaluation criteria are as follows.
○: Change rate of viscosity is less than 5%.
Δ: Viscosity change rate is 5% or more and less than 10%.
X: Change rate of viscosity is 10% or more.

2.4. Table 1 below shows the composition of each ink composition and the results of the evaluation test.

In addition, it is as follows about what was described except the compound name among the components used in Table 1.
<Pigment>
・ Carbon black (MA-100) (trade name, manufactured by Mitsubishi Chemical Corporation)
・ Carbon black (SAF-HS) (trade name, manufactured by Tokai Carbon Co., Ltd.)
・ C. I. Pigment Blue 15: 3 (copper phthalocyanine, β crystal)
<Nonaqueous solvent (nonpolar organic solvent)>
Hydrocarbon solvent (AF-4) (trade name, manufactured by JX Nippon Oil & Energy Corporation, naphthenic solvent, 50% distillation point: 257.5 ° C.)
Hydrocarbon solvent (AF-6) (trade name, manufactured by JX Nippon Oil & Energy Corporation, naphthenic solvent, 50% distillation point: 315.5 ° C.)
<Non-aqueous solvent (polar organic solvent)>
・ Methyl soybean oil (ester solvent, 50% distillation point: 345.0 ° C)
Soybean oil isobutyl (ester solvent, 50% distillation point: 356.5 ° C.)
・ Methyl oleate (trade name “EXEPEARL M-OL”, manufactured by Kao Corporation, ester solvent, 50% distillation point: 334.0 ° C.)
-Ethyl oleate (ester solvent, 50% distillation point: 344.5 ° C)
Isostearyl alcohol (alcohol solvent, 50% distillation point: 301.0 ° C.)
<Dispersant>
・ Sol Sparse 13940 (trade name, manufactured by LUBRIZO)
<Surfactant>
・ KF-6015 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., polyether-modified siloxane surfactant, HLB value: 4.5)
BY22-008M (trade name, manufactured by Toray Dow Corning Co., Ltd., siloxane-based surfactant, HLB value: 2)
・ KF-6012 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., polyether-modified siloxane surfactant, HLB value: 7)
・ KF-6013 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., siloxane-based surfactant, HLB value: 10)
New Coal 723 (trade name, manufactured by Nippon Emulsifier Co., Ltd., polyoxyethylene polycyclic phenyl ether, HLB value: 16.6)
・ Silface SAG503A (trade name, manufactured by Nissin Chemical Industry Co., Ltd., HLB value: 11)

  As shown in Table 1, according to the ink compositions of Examples 1 to 10, an image having excellent color developability (OD) was obtained as the pigment concentration was increased, and the pigment concentration was increased. In addition, it was found that by adding the specific siloxane-based surfactant, the continuous ejection stability is not impaired and the storage stability is also improved.

  On the other hand, according to the ink compositions of Comparative Examples 1 to 4, when a surfactant other than the specific siloxane surfactant is added, at least one of continuous discharge stability, color developability (OD), and storage stability is obtained. It was found that good results could not be obtained.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (7)

Containing a pigment, a non-aqueous solvent, and a surfactant,
Wherein as the surfactant, HLB value seen contains 1.0 to 7.0 of the siloxane-based surfactants,
The non-aqueous solvent includes a non-polar organic solvent having a 50% distillation point of 280 ° C. or less and a polar organic solvent having a 50% distillation point of 300 ° C. or more,
The non -aqueous inkjet ink composition whose total content of the said non-polar organic solvent and the said polar organic solvent in the said non-aqueous solvent is 60.0 mass% or more . In shear viscosity measurement with a rheometer at 20 ° C., the difference in shear viscosity between a shear rate of 20 [1 / s] and 500 [1 / s] is 0.60 [mPa · s] or less. Item 2. A non-aqueous inkjet ink composition according to Item 1 . The ratio of the pigment content to the siloxane surfactant content in the ink composition ([pigment content] / [siloxane surfactant content]) is 0.1 or more and 3. The non-aqueous inkjet ink composition according to claim 1 or 2, which is less than 0. The non-aqueous inkjet according to any one of claims 1 to 3 , wherein a content of the pigment is 5.0% by mass or more and 15.0% by mass or less with respect to a total mass of the ink composition. Ink composition. The content of the siloxane-based surfactant, relative to the total weight of the ink composition, more than 1.0 mass% to 10.0 mass%, according to any one of claims 1 to 4 A non-aqueous inkjet ink composition. The nonpolar organic solvents, aliphatic hydrocarbons, containing at least one selected from alicyclic hydrocarbons and aromatic consisting of hydrocarbon group, as claimed in any one of claims 1 to 5 Non-aqueous inkjet ink composition. As the polar organic solvent, soybean oil methyl, soybean oil isobutyl, methyl oleate, ethyl oleate, isostearyl alcohol, oleyl alcohol, isopalmitic acid, isostearic acid, isoarachidic acid, isohexacic acid, isopropyl isostearate, methyl linoleate, comprising at least one member selected from linoleic acid isobutyl and the group consisting of tall oil isobutyl, non-aqueous inkjet ink composition according to any one of claims 1 to 6.