JP2019108559A - Ink composition, and inkjet recording method and printed matter manufacturing method using the same - Google Patents

Abstract

To provide an ink composition which has good storage stability even when containing water as a main component.SOLUTION: The ink composition contains a solvent containing water and an organic solvent, a resin, a coloring material, and a surfactant. The content of the water is 50 pts.mass or more in 100 pts.mass of the ink composition. The organic solvent contains a water-soluble organic solvent having a boiling point of 120°C or higher and 250°C or lower in an amount of 80 pts.mass or more in 100 pts.mass of the organic solvent. The total content of the resin and the coloring material is 20 pts.mass or less in 100 pts.mass of the ink composition. The ink composition has a pH of 6.0 or higher and 9.0 or lower and a conductivity of 2,000 μS/cm or less.SELECTED DRAWING: None

Description

  The present invention relates mainly to an ink composition ejected by an inkjet method, an inkjet recording method using the same, and a method of producing a printed matter.

  Ink compositions in which various water-soluble dyes are dissolved in water or a mixed solution of water and an organic solvent are widely used as ink compositions. The ink composition is directly discharged onto a substrate such as paper by an ink jet method or the like, and the ink composition is attached to dry the mixed liquid, whereby characters and images can be obtained.

  Among the above-described ink compositions, ink compositions containing water as a main component containing 50% by mass or more of water in the ink composition are used. Water has a lower boiling point than the other solvents contained in the ink composition. In addition, water is a solvent that is safe and does not ignite like organic solvents, and is also excellent in environmental aspects.

  For example, Patent Document 1 discloses an ink composition including a pigment, water, a water-soluble organic solvent, and a predetermined surfactant, and the average particle diameter of the pigment is in a predetermined range. According to Patent Document 1, the ink composition described in Patent Document 1 solves the ink storability which is difficult with ink jet inks, and is an ink composition for pigment-based ink jet which is excellent in image saturation and ink storability. It is a thing.

JP 2004-315673 A

  Now, water is a solvent having a low boiling point and high safety as described above, but the components contained in the ink composition containing water as a main component are components having high affinity with water, such as electrolyte. There is a tendency to be selected.

  The ink composition containing a large amount of components of the electrolyte has high conductivity by being ionized into ions in the ink composition. However, water has a low boiling point, and when the water is evaporated, the content ratio of the organic solvent in the ink composition may be high, and the component of the electrolyte may be precipitated.

  In addition, when the ink composition is stored for a long time, ions electrolyzed in the ink composition may cause reactions such as exchange reaction, neutralization, oxidation, reduction, etc. with other components. . Then, a reactant produced by these reactions may be precipitated from the ink composition. In the case of an ink composition containing water as a main component, storage stability may be a particular problem because precipitates resulting from the components and reactants may occur.

  In particular, in the case of using an ink composition containing water as a main component for inkjet, deposits resulting from the components and reactants adhere to the inkjet nozzle and head, and the inside of the nozzle and the vicinity of the head are clogged by the deposits. In addition, the nozzle and the head may be corroded, which may further cause a problem that the discharge stability of the ink composition is lowered.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an ink composition having excellent storage stability even if the ink composition contains water as a main component.

  MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors discover that the said subject can be solved if it is the ink composition which adjusted the electrical conductivity and pH of an ink composition. It came to complete. Specifically, the present invention provides the following.

(1) containing a solvent containing water and an organic solvent, a resin, a coloring material, and a surfactant,
The content of the water is 50 parts by mass or more in 100 parts by mass of the ink composition,
The organic solvent contains 80 parts by mass or more of a water-soluble organic solvent having a boiling point of 120 ° C. or more and 250 ° C. or less in 100 parts by mass of the organic solvent,
The total content of the resin and the coloring material is 20 parts by mass or less in 100 parts by mass of the ink composition,
An ink composition having a pH of 6.0 to 9.0 and a conductivity of 2000 μS / cm or less.

  (2) The surfactant described in (1) contains at least one surfactant selected from the group consisting of polyoxyalkylene alkyl ether, fluorosurfactant, and polysiloxane surfactant. Ink composition.

  (3) The ink composition according to (1) or (2), wherein the content of the surfactant is 1 part by mass or less in 100 parts by mass of the ink composition.

  (4) The ink composition according to any one of (1) to (3), which is used in an inkjet method.

  (5) An inkjet recording method of ejecting the ink composition according to any one of (1) and (4) onto the surface of a substrate by an inkjet method.

  (6) A method for producing a printed matter, comprising the step of discharging the ink composition according to any one of (1) to (4) onto the surface of a substrate by an inkjet method.

  The ink composition of the present invention is an ink composition having high storage stability which can suppress the deposition of each component contained in the ink composition, even if the ink composition contains water as a main component.

  Hereinafter, although specific embodiments of the present invention will be described in detail, the present invention is not limited to the following embodiments in any way, and appropriate modifications may be made within the scope of the object of the present invention. can do.

<Ink composition>
The ink composition of the present embodiment is an ink composition containing a solvent, a colorant, a resin, and a surfactant. The solvent also contains water and an organic solvent. Water is 50 parts by mass or more in 100 parts by mass of the ink composition.

  In the ink composition of the present embodiment, when the content of water in the ink composition is 50 parts by mass or more, the flammability of the ink composition is reduced, and the ink composition becomes a safe ink composition. In addition, since water has a low boiling point, when the content of water in the ink composition is 50 parts by mass or more, the drying property of the ink composition can be improved. The ink composition of the present embodiment in which the content of water in the ink composition is 50 parts by mass or more may be referred to as "the ink composition of the present embodiment containing water as a main component".

  Moreover, the ink composition of the present embodiment contains 80 parts by mass or more of a water-soluble organic solvent having a boiling point of 120 ° C. or more and 250 ° C. or less in 100 parts by mass of the organic solvent. The water-soluble organic solvent refers to an organic solvent that can be dissolved in 100 parts by mass of water at 25 ° C. at 5 parts by mass or more at 1 atm. By containing 80 parts by mass or more of a water-soluble organic solvent having a boiling point of 120 ° C. or more and 250 ° C. or less in 100 parts by mass of the organic solvent, it is possible to improve nozzle moisture retention and ejection stability of the ink jet head. When the boiling point of the organic solvent is 120 ° C. or more, the odor of the ink composition due to the volatilization of the low boiling point solvent and the deposition of the component of the electrolyte can be suppressed, and the organic solvent of the low boiling point component is an inkjet head or an inkjet It is possible to reduce the risk of problems caused by swelling or dissolution of the resin member of the recording apparatus. By setting the boiling point of the organic solvent to 300 ° C. or less, the drying property of the ink composition can be improved. The water-soluble organic solvent is preferably dissolved 50 parts by mass or more in 100 parts by mass of water at 25 ° C. under 1 atmospheric pressure, more preferably dissolved in 70 parts by mass or more, and dissolved in 80 parts by mass or more Is more preferred.

  In addition, the ink composition of the present embodiment is adjusted to have a conductivity of 2000 μS / cm or less and a pH of 6.0 or more and 9.0 or less. By adjusting the conductivity and the pH of the ink composition, precipitation of each component contained in the ink composition can be suppressed. The conductivity and the pH mainly depend on the content and type of the solvent, the resin, the coloring material and the surfactant contained in the ink composition.

  Even if the ink composition of the present embodiment is an ink composition containing water as a main component by adjusting the conductivity and the pH of the ink composition, precipitates resulting from the components and the reactant are obtained. Ink composition having high storage stability capable of suppressing the deposition of The conductivity can be measured at 25 ° C. using, for example, EC Testr 11+ manufactured by Eutech Instruments. The pH can be measured, for example, by HM-30R manufactured by Toa DK.

  In particular, when an ink composition is used for inkjet, precipitates adhere to the inside of the inkjet head or in the vicinity of the nozzle, causing clogging of the nozzle or the head or corrosion of the metal part, and the ejection stability of the ink composition decreases. Sometimes. The ink composition according to the present embodiment is an ink composition having high storage stability that can suppress the deposition of precipitates caused by the components and reactants even if the ink composition is mainly composed of water. Therefore, the corrosion of the inkjet nozzle and the head can be prevented, and the deposition stability of the ink composition can be suppressed from being reduced by the deposition of the deposits. The ink composition of this embodiment is not particularly limited to the method used for the recording method (printing method), but it can suppress the decrease in discharge stability, which is a problem of the ink jet method. Since it is an ink composition which can also improve the durability of the head and the nozzle, it is an ink composition suitable for use in the ink jet system.

  The piezo method has a longer distance for reciprocating the fluid (ink composition) at a higher speed than the thermal method. Further, with the recent increase in density and accuracy of the ink jet system, the width of the flow path connected to the nozzle is narrowed, and the nozzle hole is reduced in size and in density. Therefore, when the ink composition is discharged by the piezo method, there is a high possibility that problems occur in the discharge of the ink composition. An ink composition containing water as a main component and further containing a resin emulsion and other components (for example, a coloring material) is an ink jet recording apparatus by evaporation (volatilization) of water contained in the ink composition. There is a tendency that the components contained in the ink composition may be generated as precipitates in the inside of the head and in the vicinity of the nozzle as compared to an ink composition not containing water as a main component. However, the ink composition of the present embodiment can maintain good ejection stability even with a piezoelectric inkjet recording device. Further, in the case of the thermal system, it is possible to suppress the kogation due to heat when discharging the ink composition, and even in the case of the thermal type ink jet recording apparatus, the discharge stability can be maintained favorably.

  Next, each component contained in the ink composition of the present embodiment will be described.

[solvent]
The solvent contained in the ink composition of the present embodiment is a solvent containing water and an organic solvent. As water to be contained, it is preferable not to contain various ions, and to use deionized water. The content of water is not particularly limited as long as it is 50 parts by mass or more in 100 parts by mass of the ink composition, but 55 parts by mass or more in 100 parts by mass of the ink composition is preferable, and the ink composition is preferable. The amount is preferably 60 parts by mass or more in 100 parts by mass. When the content of water is 50 parts by mass or more in 100 parts by mass of the ink composition, the flammability of the ink composition is reduced, and the ink composition becomes safe. In addition, since water has a low boiling point, when the content of water in the ink composition is 50 parts by mass or more, the drying property of the ink composition can be improved.

  Moreover, as an organic solvent to be contained, a water-soluble organic solvent having a boiling point of 120 ° C. to 250 ° C. can be mentioned. In the ink composition of the present embodiment, the organic solvent contains 80 parts by mass or more of a water-soluble organic solvent having a boiling point of 120 ° C. or more and 250 ° C. or less in 100 parts by mass of the organic solvent. The organic solvent preferably contains 90 parts by mass or more of a water-soluble organic solvent having a boiling point of 120 ° C. or more and 250 ° C. or less in 100 parts by mass of the organic solvent.

  Examples of the water-soluble organic solvent having a boiling point of 120 ° C. to 250 ° C. include heterocyclic compounds having a C = O bond having a boiling point of 120 ° C. to 250 ° C., and alkanediol compounds having a boiling point of 120 ° C. to 250 ° C. . The heterocyclic compound having a C = O bond having a boiling point of 120 ° C. or more and 250 ° C. or less is preferably contained in an amount of 3 parts by mass or more in 100 parts by mass of the ink composition. The amount is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the ink composition. The heterocyclic compound having a C = O bond having a boiling point of 120 ° C. or more and 250 ° C. or less is contained in an amount of 3 parts by mass or more in 100 parts by mass of the ink composition. The ink is hard to be repelled, an image can be appropriately formed, and the stability of the ink, the nozzle moisturizing property of the ink jet head, the discharge stability, and the water resistance of the coating film can be made good.

  Examples of the heterocyclic compound having a C = O bond include 2-pyrrolidone, β-propiolactone, γ-butyrolactone, δ-valerolactone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 2 -Imidazolidinone, 1,3-dimethyl-2-imidazolidinone, pyrrolidone carboxylic acid, ethylene carbonate, propylene carbonate, α-lactam, β-lactam, γ-lactam, δ-lactam and the like can be mentioned. Among the heterocyclic compounds having a C = O bond, 2-pyrrolidone and N-methyl-2-pyrrolidone are preferably used.

  The alkanediol compound having a boiling point of 120 ° C. to 250 ° C. is preferably contained in an amount of 5 parts by mass or more in 100 parts by mass of the ink composition, and more preferably 10 parts by mass or more in 100 parts by mass of the ink composition. The alkanediol compound having a boiling point of 120 ° C. or more and 250 ° C. or less is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less in 100 parts by mass of the ink composition. The alkanediol compound having a boiling point of 120 ° C. or more and 250 ° C. or less is contained in an amount of 5 parts by mass or more in 100 parts by mass of the ink composition, whereby the ink composition is not easily repelled even if the substrate is a resin substrate. An image can be formed, and the stability of the ink, the nozzle moisture retention of the ink jet head, and the ejection stability can be improved.

  As the alkanediol compound having a boiling point of 120 ° C. or more and 250 ° C. or less, for example, 2-methyl-1,3-pentanediol, 2-methyl-1,3-propanediol, 1,2-hexanediol, 1,2-butane Diol, propylene glycol, diethylene glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,2- Examples include pentanediol, 1,5-pentanediol, 3-methyl-1,3-butanediol, ethylene glycol, 2-methyl-2,4-pentanediol and the like.

  The alkanediol compound having a boiling point of 120 ° C. or more and 250 ° C. or less preferably contains 2-methyl-1,3-pentanediol and / or 2-methyl-1,3-propanediol. 2-methyl-1,3-pentanediol and 2-methyl-1,3-propanediol can improve the spread of the ink on the substrate, and the ink fixability to the substrate is also good. It can be

  Further, the organic solvent contained in the ink composition of the present embodiment includes a heterocyclic compound having a C = O bond having a boiling point of 120 ° C. to 250 ° C. and an alkanediol compound having a boiling point of 120 ° C. to 250 ° C. It may contain an organic solvent. Examples of the organic solvent other than alkanediol having 7 or less carbon atoms include alkyl alcohols; 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-propanol, 1-methoxy-2-propanol, 3- Monovalent alcohols such as methoxy-n-butanol; 1-dimethylformamide, dimethylacetamide, 3-methoxypropanamide, 3-butoxypropanamide, N, N-dimethyl-3-methoxypropanamide, N, N-dibutyl Amides such as -3-methoxypropanamide, N, N-dibutyl-3-butoxypropanamide, N, N-dimethyl-3-butoxypropanamide; ketones such as acetone and diacetone alcohol or keto alcohols; tetrahydrofuran, Ethers such as dioxane; polyethylene glycol Oxyethylene or oxypropylene copolymers such as polypropylene glycol; triols such as glycerin, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol: tetrahydric alcohols such as mesoerythritol, pentaerythritol, etc. Ethylene glycol monomethyl (or ethyl, isopropyl, n-butyl, isobutyl, n-hexyl, 2-ethylhexyl) ether, diethylene glycol monomethyl (or ethyl, isopropyl, n-butyl, isobutyl, n-hexyl, 2-ethylhexyl) ether; Triethylene glycol monomethyl (or ethyl, isopropyl, n-butyl, isobutyl) ether, propylene glycol monomethyl (or ethyl, isopropyl, n-butyl, iso Monoalkyl ethers such as ethyl, dipropylene glycol monomethyl (or ethyl, isopropyl, n-butyl, isobutyl) ether; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether And dialkyl ethers of polyhydric alcohols such as tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether; monoethanolamine, diethanolamine, triethano And alkanolamines such as N-methyl ethanolamine, N-ethyl ethanolamine, N-butyl ethanolamine, N-methyl diethanolamine, N-ethyl diethanolamine, N-butyl diethanolamine, cyclic compounds such as sulfolane, and the like.

  The heterocyclic compound having a C 複 素 O bond having a boiling point of 120 ° C. or more and 250 ° C. or less and the organic solvent other than the alkanediol compound having a boiling point of 120 ° C. or more and 250 ° C. or less are contained in 20 parts by mass or less in 100 parts by mass of the ink composition. Is preferable, and 10 parts by mass or less of 100 parts by mass of the ink composition is more preferable.

[resin]
The ink composition of the present embodiment contains a resin. By containing the resin in the ink composition, the fixability and the water resistance of the printed matter are improved. Further, in the ink composition of the present embodiment, it is preferable that at least a part of the contained resin is contained as a resin emulsion. In the ink composition of the present embodiment, the resin emulsion means an aqueous dispersion in which the continuous phase is a water-soluble solvent and the dispersed particles are resin fine particles. By forming the resin emulsion, the resin can be dispersed in the ink composition as fine resin particles by electrostatic repulsion or steric repulsion. The resin emulsion generally has the property of thickening and aggregating when the water-soluble solvent, which is a continuous phase, is reduced by evaporation, permeation and the like, and has an effect of promoting the fixing of the coloring material to the substrate.

  The resin contained in the ink composition of the present embodiment is not particularly limited as long as the pH and the conductivity of the ink composition can fall within a predetermined range, but, for example, acrylic resin, polystyrene Use resin, polyester resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride vinyl acetate copolymer resin, polyethylene resin, urethane resin, silicone (silicon) resin, acrylamide resin, epoxy resin, or copolymer resin or mixture of these Can. These are preferable in that they can improve solvent resistance in addition to water resistance. Among them, an acrylic resin is preferable because it can be excellent in discharge stability, water resistance and solvent resistance.

  It will not specifically limit, if it is what is contained as a main component of the monomer which comprises a (meth) acrylic acid ester monomer as an acrylic resin. A well-known compound can be used as a (meth) acrylic acid ester monomer, A monofunctional (meth) acrylic acid ester can be used preferably. For example, (meth) acrylic acid alkyl ester, (meth) acrylic acid aralkyl ester, (meth) acrylic acid alkoxy alkyl ester etc. can be mentioned. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, -iso-propyl (meth) acrylate, n-butyl (meth) acrylate , (Meth) acrylic acid-sec-butyl, (meth) acrylic acid-iso-butyl, (meth) acrylic acid-tert-butyl, pentyl (meth) acrylic acid, neopentyl (meth) acrylic acid, (meth) acrylic acid Hexyl, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, -iso-octyl (meth) acrylate, nonyl (meth) acrylate, -iso-nonyl (meth) acrylate, (meth) acrylic Dodecyl acid, tridecyl (meth) acrylate, stearyl (meth) acrylate, cyclopentyl (meth) acrylate, ( Ta) cyclohexyl acrylate, (meth) acrylic acid-2-methylcyclohexyl, (meth) acrylic acid dicyclopentanyl, (meth) acrylic acid dicyclopentenyl, (meth) acrylic acid dicyclopentanyloxyethyl (meth ) Dicyclopentenyl oxyethyl acrylate, dicyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, allyl (meth) acrylate, propargyl (meth) acrylate, phenyl (meth) acrylate Naphthyl (meth) acrylate, anthracenyl (meth) acrylate, anthraninonyl (meth) acrylate, piperonyl (meth) acrylate, salicylic (meth) acrylate, furyl (meth) acrylate, (meth) acrylic acid Furfuryl, (Meth) Acrylic Tetrahydrofuryl, tetrahydrofurfuryl (meth) acrylate, pyranyl (meth) acrylate, benzyl (meth) acrylate, phenethyl (meth) acrylate, cresyl (meth) acrylate, glycidyl (meth) acrylate, (meth) Acrylic acid-3,4-epoxycyclohexylmethyl, (meth) acrylic acid-3,4-epoxycyclohexylethyl, (meth) acrylic acid-1,1,1-trifluoroethyl, (meth) acrylic acid perfluoroethyl Perfluoro-n-propyl (meth) acrylate, Perfluoro-iso-propyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, triphenylmethyl (meth) acrylate, cumyl (meth) acrylate , (Meth) acrylic acid 3- (N, N-dimethylamino) Propyl, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (meth) acrylate (Meth) acrylic esters such as diethylaminoethyl, trimethoxysilylpropyl (meth) acrylate, triethoxysilylpropyl (meth) acrylate, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, etc. , Etc. In addition, "(meth) acryl" means both "acryl" and "methacryl." These monomers can be obtained from Mitsubishi Rayon Co., Ltd., Nippon Oil and Fats Co., Ltd., Mitsubishi Chemical Co., Ltd., Hitachi Chemical Co., Ltd., and the like.

  The monomer constituting the acrylic resin may contain an acid group-containing monomer having an acid group, a hydroxyl group-containing monomer having a hydroxyl group, and an amino group-containing monomer having an amino group. Examples of the acid group-containing monomer having an acid group include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, citraconic acid, maleic anhydride, maleic acid monomethyl ester, and maleic acid monobutyl ester. Ethylenic non-ethylenic materials such as carboxyl group-containing aliphatic monomers such as itaconic acid monomethyl ester, itaconic acid monobutyl ester, vinyl benzoic acid, monohydroxyethyl (meth) acrylate oxalate, and carboxyl terminal caprolactone modified (meth) acrylate Mention may be made of carboxyl group-containing monomers having a saturated double bond and a carboxyl group.

  The hydroxyl group-containing monomer containing a hydroxyl group is not particularly limited as long as it has an unsaturated double bond and a hydroxyl group, and examples thereof include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) ) Acrylate, 3-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, caprolactone modified hydroxy (meth) acrylate, methyl α- (Hydroxymethyl) (meth) acrylate, ethyl α- (hydroxymethyl) (meth) acrylate, n-butyl α- (hydroxymethyl) (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 4- Hydroki Butyl (meth) acrylate, and the like. The amino group-containing monomer is not particularly limited as long as it has an unsaturated double bond and an amino group, and examples thereof include (meth) acrylamide N-monomethyl (meth) acrylamide, N-monoethyl (meth) ) Acrylamide, N, N-Dimethyl (meth) acrylamide, N-n-Propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, methylenebis (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl ( Acrylamide compounds such as meth) acrylamide, dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl acrylamide, diacetone acrylamide, etc., dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate , Nitrogen-containing (meth) acrylate compounds such as ethylene oxide addition (meth) acrylate of morpholine, N-vinylpyrrolidone, N-vinylpyridine, N-vinylimidazole, N-vinylpyrrole, N-vinyloxazolidone, N-vinyl Succinimide, N-vinyl methyl carbamate, N, N- methyl vinyl acetamide, (meth) acryloyloxyethyl trimethyl ammonium chloride, 2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, (meth) acrylonitrile etc. It can be mentioned.

  Moreover, as a monomer which comprises an acrylic resin, you may have another monomer other than the said (meth) acrylic acid ester monomer etc. as needed. Such other monomers are particularly limited as long as they can be copolymerized with the above (meth) acrylic acid ester monomer and can have desired water resistance and solvent resistance. Instead, it may be a monofunctional monomer having one ethylenic unsaturated double bond or a polyfunctional monomer having two or more. For example, vinyl monomers such as vinyl acetate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, N-vinyl pyrrolidone, vinyl pyridine, N-vinyl carbazole, vinyl imidazole, vinyl ether, vinyl ketone, vinyl pyrrolidone, etc .; styrene, styrene α-, o-, m-, p-alkyl, nitro, cyano, amides, ester derivatives, vinyl aromatic monomers such as vinyl toluene and chlorostyrene; olefin monomers such as ethylene, propylene and isopropylene; butadiene and chloroprene A diene monomer; vinyl cyanide compound monomers such as acrylonitrile and methacrylonitrile can be used. And diacrylate compounds such as polyethylene glycol diacrylate, triethylene glycol diacrylate, 1, 3-butylene glycol diacrylate; and triacrylate compounds such as trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate. Dimethacrylate compounds such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and triethylene glycol dimethacrylate; trimethacrylate compounds such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; divinyl benzene and the like.

  Among them, aromatic vinyl monomers and carboxyl group-containing monomers having an ethylenically unsaturated double bond and a carboxyl group are preferable. Even in the ink composition of the present embodiment containing water as a main component, a resin composed of an aromatic vinyl monomer, and a carboxyl group-containing monomer having an ethylenically unsaturated double bond and a carboxyl group is contained. Also, it is possible to make the wettability to the substrate, the coating film resistance, and the ink stability more excellent.

  An acrylic resin can be formed using these monomers, but the form of copolymerization of the monomers is not particularly limited. For example, block copolymers, random copolymers, graft copolymers, etc. should be used. Can. The resin emulsion can be produced, for example, by an emulsion polymerization reaction and neutralization after the reaction. As the emulsifying agent, a conventional high molecular weight surfactant may be used, or a reactive surfactant having an unsaturated bond may be used. The synthesis method is not particularly limited, and, for example, water, a monomer, an emulsifier, and polymerization initiation in the presence of a reactive surfactant, a nonreactive surfactant, polyvinyl alcohol, a cellulose derivative, etc. The emulsion polymerization can be carried out by mixing with an agent. The resin emulsion can also be obtained by mixing a resin solution with water together with a surfactant, without causing an emulsion polymerization reaction. For example, it can be obtained by adding and mixing a solution of a resin composed of (meth) acrylic acid ester or styrene and a (meth) acrylic acid ester and a surfactant in water.

  As a commercially available resin emulsion, for example, Acrit WEM-031 U, WEM-200 U, WEM-321, WEM-3000, WEM-202 U, WEM-3008 (manufactured by Taisei Fine Chemical Co., Ltd., acrylic-urethane resin emulsion), Acrit UW-550CS, UW-223SX, AKW107, RKW-500 (manufactured by Taisei Fine Chemical Co., Ltd., acrylic resin emulsion), LUBRIJET N240 (manufactured by Lubrizol, acrylic resin emulsion), Superflex 150, 210, 470, 500M, 620, 650, E2000, E4800, R5002 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion), bini bran 701 FE 35, 701 FE 50, 701 FE 65, 700, 701, 71 , 737, 747 (manufactured by Nisshin Chemical Co., Ltd., vinyl chloride-acrylic resin emulsion), Vinibran 2706, 2685 (manufactured by Nisshin Chemical Co., Ltd., acrylic resin emulsion), Movinyl 743 N, 6600, 7470, 7720, (Japan Although Synthetic Chemical Co., Ltd. product, an acrylic resin emulsion) etc. can be illustrated, it is not limited to these.

  The average particle diameter of the resin emulsion is preferably 30 nm or more, and more preferably 50 nm or more, from the viewpoint of dispersion stability in the ink composition and inkjet dischargeability. The average particle diameter of the resin emulsion is preferably 300 nm or less, and more preferably 250 nm or less, from the viewpoint of dispersion stability in the ink composition and inkjet dischargeability. In the present embodiment, the number average particle diameter of the pigment can be measured using a concentrated particle size analyzer (manufactured by Otsuka Electronics Co., Ltd., model: FPAR-1000) at a measurement temperature of 25 ° C.

  From the viewpoint of membrane water resistance, the mass average molecular weight of the resin emulsion is preferably 10000 or more, and more preferably 100000 or more. From the viewpoint of the stability of the ink composition, the mass average molecular weight of the resin emulsion is preferably 1,000,000 or less, and more preferably 500,000 or less. In addition, in this embodiment, the molecular weight of resin shows the mass mean molecular weight Mw, is a value measured by GPC (gel permeation chromatography), and it is "HLC-8120GPC" made by Tosoh Corp. The polystyrene standard for calibration curve can be used as a standard.

  The glass transition point (Tg) of the resin emulsion is capable of forming printed matter having water resistance, solvent resistance and scratch resistance even when printed on a low absorbing substrate or non-absorbing substrate, 0 ° C. or higher is preferable because it is possible to avoid applying high temperature to form a printed matter, and to make unnecessary a lot of energy and to make the printing substrate less susceptible to heat damage, 10 degreeC or more is more preferable, and 20 degreeC or more is still more preferable. Moreover, 100 degrees C or less is preferable, 90 degrees C or less is more preferable, and 80 degrees C or less is still more preferable. The glass transition temperature (Tg) can be measured, for example, using a differential scanning calorimeter "DSC-50" manufactured by Shimadzu Corporation.

  The resin emulsion is not limited to any one of cationic, nonionic and anionic, but the acid value of the resin emulsion is 0.01 mg KOH / g or more from the viewpoint of the storage stability of the ink composition and the like. Is preferred. The acid value of the resin emulsion is preferably 25 mg KOH / g or less from the viewpoint of water resistance of printed matter, storage stability of the ink composition, and the like. In the present invention, the acid value refers to the mass (mg) of potassium hydroxide required to neutralize the acidic component contained in 1 g of the sample (solid content of resin), and is described in JIS K 0070. It can be measured by a method according to the method of

  In the ink composition of the present embodiment, the mass part of the resin contained in 100 parts by mass of the ink composition is not particularly limited as long as it can form a print having desired water resistance and solvent resistance. For example, the content of the ink composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and further preferably 0.5 parts by mass or more, and 1 part by mass It is more preferable that it is more than. Further, it is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less in the ink composition.

[Color material]
The ink composition of the present embodiment contains a colorant. The colorant is not particularly limited as long as the pH and the conductivity of the ink composition can fall within the predetermined range. As the coloring material, a dye or a pigment generally used in the ink composition can be used. Examples of the pigment include inorganic pigments and organic pigments. These may be used singly or in combination of two or more.

  Examples of organic pigments include insoluble azo pigments, soluble azo pigments, derivatives from dyes, phthalocyanine pigments, quinacridone pigments, perylene pigments, dioxazine pigments, nickel azo pigments, isoindolinone pigments, pyranthrone pigments, thioindigo pigments, condensation azo pigments, Examples of the organic solid solution pigment such as benzimidazolone pigment, quinophthalone pigment, isoindoline pigment, quinacridone solid solution pigment, perylene solid solution pigment, and other pigments include carbon black.

  When organic pigments are exemplified by color index (C.I.) numbers, C.I. I. Pigment yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 73, 74, 75, 83, 95, 97, 98, 109, 110, 114, 117, 120, 125, 128, 129, 130, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185, 213, 214; I. Pigment red 5, 7, 9, 12, 48, 49, 52, 53, 57, 97, 112, 122, 123, 149, 168, 177, 180, 184, 192, 202, 206, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254; I. Pigment orange 16, 36, 43, 51, 55, 59, 61, 64, 71; I. Pigment violet 19, 23, 29, 30, 37, 40, 50; C.I. I. Pigment blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64; I. Pigment green 7, 36, 58; C.I. I. Pigment browns 23, 25, 26 and the like.

  As the inorganic pigment, for example, barium sulfate, iron oxide, zinc oxide, barium carbonate, barium sulfate, silica, clay, talc, titanium oxide, calcium carbonate, synthetic mica, alumina, zinc flower, lead sulfate, yellow lead, zinc yellow And iron red (red iron oxide (III)), cadmium red, ultramarine blue, bitumen, chromium oxide green, cobalt green, amber, titanium black, synthetic iron black, inorganic solid solution pigments and the like.

  The average dispersed particle size of the pigment is not particularly limited as long as desired color development is possible. Although it varies depending on the type of pigment, it is preferably in the range of 10 nm or more, and more preferably in the range of 30 nm or more from the viewpoint of achieving good dispersion stability of the pigment and sufficient coloring power. The average dispersed particle size of the pigment is preferably in the range of 300 nm or less, and more preferably in the range of 200 nm or less. If the average dispersion particle size is 300 nm or less, clogging of the nozzles of the inkjet head is unlikely to occur, and a highly reproducible homogeneous image can be obtained. When the average dispersion particle size is 10 nm or more, the light resistance of the obtained printed matter can be made favorable.

  The content of the pigment is not particularly limited as long as it can form a desired image, and is appropriately adjusted. Specifically, the amount is preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more, with respect to 100 parts by mass of the ink composition, although it varies depending on the type of the pigment. The amount is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, based on 100 parts by mass of the ink composition. When the content of the pigment is 20 parts by mass or less, the balance between the dispersion stability of the pigment and the coloring power can be excellent.

[Pigment dispersant]
The ink composition of the present embodiment may contain a pigment dispersant. Here, the pigment dispersant means a resin or surfactant having a function of improving the dispersibility of the pigment in the ink by adhering to a part of the pigment surface.

  In the ink composition of the present embodiment, the pigment dispersant that can be used is not particularly limited. For example, surfactants such as cationic, anionic, nonionic, amphoteric, silicone (silicon), and fluorinated surfactants can be used. Among the surfactants, polymer surfactants (polymer dispersants) as exemplified below are preferable.

  As a pigment dispersant that can be used in the ink composition of the present embodiment, a water-soluble polymer dispersant can be preferably used. Examples of water-soluble polymer dispersants include polyester-based, polyacrylic-based, polyurethane-based, polyamine-based and polycaptolactone-based main chains, and an amino group, a carboxy group, a sulfo group and a hydroxy group as side chains. And dispersants having a polar group such as For example, (co) polymers of unsaturated carboxylic acid esters such as polyacrylic acid esters; copolymers of aromatic vinyl compounds such as styrene and α-methylstyrene and unsaturated carboxylic acid esters such as acrylic acid esters; (Partial) amine salt of (co) polymer of unsaturated carboxylic acid such as polyacrylic acid, (partial) ammonium salt or (partial) alkylamine salt; hydroxyl group-containing unsaturated carboxylic acid ester such as hydroxyl group-containing polyacrylic acid ester (Co) polymers and their modified products; polyurethanes; unsaturated polyamides; polysiloxanes; long-chain polyaminoamide phosphates; polyethyleneimine derivatives (poly (lower alkyleneimine) and free carboxyl group-containing polyester Amides obtained by reaction and their bases); polyallylamine derivatives (polyallyl Reaction product obtained by reacting Min with one or more compounds selected from polyester, polyamide or ester and co-condensate of ester (amide of polyester) having free carboxyl group) Etc. Among them, a water-soluble polymer dispersant containing a (meth) acrylic resin is preferable from the viewpoint of the dispersion stability of the ink and the image sharpness of the printed matter.

  Specific examples of the water-soluble polymer dispersant include SMA 1440 made by SARTOMER, SMA 2625, SMA 17352, SMA 3840, SMA 1000, SMA 2000, SMA 3000, JONCRYL 67, JONCRYL 678, JONCRYL586, JONCRYL 680, JONCRYL 682, JONCRYL 690, JONCRYL -JDX5050, EFKA4550, EFKA4560, EFKA4585, EFKA5220, EFKA6230, Lubrizole SOLSPERSE 20000, SOLSPERSE 27000, SOLSPERSE 41000, SOLSPERSE 41090, SOLSPERSE 43000, SOLSPE SE44000, SOLSPERSE 46000, SOLSPERSE 47000, SOLSPERSE 54000, BYKJET-9150, BYKJET-9151, BYKJET-9170, DISPERBYK-168, DISPERBYK-190, DISPERBYK- 198, DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2015, etc. Be These pigment dispersants can be suitably used in the ink composition of the present embodiment.

  In the ink composition of the present embodiment, the pigment which can be used is a pigment dispersion in which a pigment is dispersed in a water-soluble solvent by a pigment dispersant, and a hydrophilic group is directly modified on the surface of the pigment The pigment dispersion may be a self-dispersion pigment. In the present embodiment, a pigment that can be used in an ink jet recording ink may use a plurality of the aforementioned organic pigments or inorganic pigments in combination, and a pigment dispersion dispersed in a water-soluble solvent by the aforementioned pigment dispersant. And a self-dispersible pigment described later may be used in combination.

[Surfactant]
The ink composition of this embodiment contains a surfactant. The surfactant is not particularly limited, but, for example, an anionic surfactant, a cationic surfactant, a polyoxyalkylene alkyl ether, a polyoxyalkylene benzyl phenyl ether or an acetylene which may be alkylene oxide modified. Nonionic surfactants such as glycol surfactants, amphoteric surfactants, fluoro surfactants, and polysiloxane surfactants can be mentioned.

  Among the ink compositions of the present embodiment, it is preferable to contain at least one surfactant selected from the group consisting of polyoxyalkylene alkyl ether, fluorosurfactant, and polysiloxane surfactant. . Even if it is an ink composition which has water as a main component, it becomes an ink composition in which wettability and spread nature are good to substrates, such as a resin substrate.

  Examples of the polyoxyalkylene alkyl ether include polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, and polyoxyethylene polyoxypropylene alkyl ether. Among them, polyoxyethylene alkyl ether can be preferably used. Even if it is an ink composition which has water as a main component, it becomes an ink composition in which wettability and spread nature are good to substrates, such as a resin substrate.

  The polyoxyalkylene alkyl ether is, for example, nonionic P-208, P-210, P-213, E-202S, E-205S, E-215, K-204, K-220, S-207, S-215, A-10R, A-13P, NC-203, NC-207 (manufactured by NOF Corporation), Emulgen 106, 108, 707, 709, A-90, A-60 (manufactured by Kao Corporation), Floren G -70, D-90 (manufactured by Kyoeisha Chemical Co., Ltd.), Poem J-0081HV (manufactured by Riken Vitamins Co., Ltd.), adetol NP-620, NP-650, NP-660, NP-675, NP-683, NP -686, Adekacol CS-141E, TS-230E (manufactured by Adeka Co., Ltd.), etc., Solgen 30V, 40, TW-20, TW-80, Neugen CX-100 (Daiichi Kogyo Co., Ltd. Drugs Ltd.) and the like.

  Examples of the fluorine-based surfactant include polyoxyalkylene fluorinated alkyl ether, fluorinated alkyl hydrophilic group-containing oligomer, fluorinated alkyl ester addition polymer, etc., among which nonionic polyoxyalkylene fluorinated alkyl ether It is more preferable to contain The wettability and spreadability to the substrate can be further improved.

  By containing a polyoxyalkylene fluorinated alkyl ether, even the ink composition of the present embodiment having water as a main component has an effect of greatly reducing the static surface tension, so the static surface tension is in a preferable range. can do. Therefore, as the surfactant contained in the ink composition of the present embodiment, it is preferable to use a surfactant containing a polyoxyalkylene fluorinated alkyl ether.

  Examples of the fluorine-based surfactant include Megafac (manufactured by DIC Corporation), Surfron (manufactured by AGC Seimi Chemical Co., Ltd.), Ftergent (manufactured by Neos Corporation), and the like.

  As the polysiloxane surfactant, an organically modified polysiloxane surfactant is preferably used, and in the present invention, a polyether group-modified polysiloxane compound having a polyether group can be preferably used.

  As a polysiloxane compound, as a commercial item, for example, FZ-2122, FZ-2110, FZ-7006, FZ-2166, FZ-2164, FZ-7001, FZ-2120, SH 8400, FZ-7002, FZ-2104 8029 ADDITIVE, 8032 ADDITIVE, 57 ADDITIVE, 67 ADDITIVE, 86 ADDITIVE, 8616 ADDITIVE (all are manufactured by Toray Dow Corning, Inc.), KF-6012, KF-6015, KF-6004, KF-6013, KF-6011, KF-6043 KP-104, 110, 112, 323, 341 (all from Shin-Etsu Chemical Co., Ltd.), BYK-300 / 302, BYK-301, BYK-306, BYK-307, BYK-320, BYK-325. , BYK-330 BYK-331, BYK-333, BYK-337, BYK-341, BYK-342, BYK-344, BYK-345 / 346, BYK-347, BYK-348, BYK-349, BYK-375, BYK-377, BYK-378, BYK-UV 3500, BYK-UV 3510, BYK-310, BYK-315, BYK-370, BYK-UV 3570, BYK-322, BYK-323, BYK-3455, BYK-Silclean 3700 (all are manufactured by Bick Chemie, Inc.) ), Silface SAG 503A, Silface SJM-002, Silface SJM-003 (all from Nisshin Chemical Industry Co., Ltd.), TEGO Twin 4000, TEGO Twin 4100, TEGO Wet 240, TEGO Wet 25 , TEGO Wet 240, (both, Evonik Co., Ltd.) and the like can be given.

  Specific examples of the alkylene oxide non-modified acetylene glycol surfactant include 2,5-dimethyl-3-hexyne-2,5-diol, 3,6-dimethyl-4-octin-3,6-diol, 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-butyn-3-ol, 3-methyl Examples include 1-pentin-3-ol, 3-hexyne-2,5-diol, 2-butyne-1,4-diol and the like. Moreover, as a commercial item, Surfynol 61, 82, 104 (all are products made by Air Products) etc. can be used.

  Specific examples of the alkylene oxide-modified acetylene glycol surfactant include Surfynol 420, 440, 465, 485, TG, 2502, Dynol 604, 607 (all manufactured by Air Products), Surfynol SE, MD. -20, Olfin E1004, E1010, PD-004, EXP 4300, PD-501, PD-502, SPC (all from Nisshin Chemical Industry Co., Ltd.), Acetylenol EH, E40, E60, E81, E100, E200 ( Both include Kawaken Fine Chemical Co., Ltd.) and the like.

  For example, anionic surfactants such as alkyl sulfates, polyoxyalkylene derivatives, polyoxyethylene alkyl ether sulfates, alkyl benzene sulfonates, and cationic interfaces such as alkylamines and quaternary ammonium salts An activator and the like can also be contained as long as the pH, conductivity and other physical properties of the ink composition are not impaired.

  These surfactants may be used alone or in combination of two or more. The content of the surfactant is appropriately adjusted in accordance with the ink miscibility, the cleaning property, the wettability to the inner wall of the flow path, and the ink jet discharge property, and preferably 0.05 parts by mass or more in 100 parts by mass of the ink composition. More preferably, it is contained 0.1 mass part or more. In addition, preferably 5 parts by mass or less and 3 parts by mass or less are contained in 100 parts by mass of the ink composition.

[Other additives]
The ink composition of the present embodiment may further contain conventionally known additives, if necessary. Additives include, for example, viscosity modifiers, surfactants, pH adjusters, surface tension modifiers, leveling agents, antifoaming agents, antioxidants, preservatives, mildewproofing agents, charge control agents, wetting agents, etc. Known additives may be mentioned as optional components.

<Method of Producing Ink Composition>
The method for producing the ink composition of the present embodiment can include a production method for producing an ink composition by mixing a coloring material, a resin, and a solvent containing water and an organic solvent.

  For example, a method of preparing by adding an organic solvent, water, a coloring material, a resin, a surfactant and other components as necessary, adding a coloring material and a dispersing agent to a solvent containing water and an organic solvent After dispersion, a method of preparing by adding a resin, a surfactant and other components as needed, a solvent containing water and an organic solvent, a coloring material, a resin, a surfactant and other components as needed After adding the components, a method of dispersing and preparing a coloring material may, for example, be mentioned.

<Ink jet recording method>
In the inkjet recording method using the recording ink composition of the present embodiment, the substrate is not particularly limited, and as described above, any of the absorbent substrate, the low-absorbent substrate, and the non-absorbent substrate Can also be suitably used.

  An ink jet recording method (hereinafter, may be simply referred to as an ink jet recording method) using the ink composition of the present embodiment is not particularly limited. The inkjet recording method which discharges the ink composition of embodiment can be mentioned. By using the ink composition of the present embodiment, it is possible to realize an inkjet recording method which is excellent in member suitability of the inkjet head and the inkjet recording apparatus and excellent in maintainability. Further, in the ink composition of the present embodiment, even when the ink composition is discharged onto the resin substrate, the ink composition is not easily repelled by the substrate.

  The ink composition of the present embodiment can be applied to any ink jet recording apparatus such as a piezo system, a thermal system, and an electrostatic system. The type of the ink jet printing method is not particularly limited, and may be a serial head type ink jet method or a line head type ink jet method.

<Production method of printed matter>
Printed matter can be manufactured using the recording ink composition of the present embodiment. For example, there can be mentioned a method for producing a printed matter, which includes the step of discharging onto the surface of a substrate by the inkjet method described above.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these descriptions.

Preparation of Ink Composition
The ink compositions of Examples and Comparative Examples were prepared as follows using a colorant (pigment dispersion), a resin (resin emulsion), water (ion-exchanged water), a surfactant and an organic solvent. The adjustment method of a pigment dispersion and resin (resin emulsion) is shown below.

1. Preparation of pigment dispersion A pigment dispersant was prepared by the following method.

1-1. Preparation of pigment dispersant 1 90 g of styrene, 15 g of acrylic acid, 15 g of methacrylic acid, a mixture of 30 g of butyl acrylate and 3.6 g of tert-butylperoxy-2-ethylhexanoate in 200 g of toluene kept at 100 ° C. Was added dropwise over 1.5 hours. After completion of the dropwise addition, the mixture was reacted at 100 ° C. for 2 hours and then cooled to obtain a resin solution. The resin was purified from the resin solution with hexane to obtain a pigment dispersant 1 having a mass average molecular weight of 18,000 and an acid value of 65 mg KOH / g.

1-2. Preparation of pigment dispersant 2 In 200 g of toluene kept at 100 ° C., 48 g of methyl methacrylate, 27 g of butyl acrylate, 30 g of butyl methacrylate, 12 g of acrylic acid, 9 g of methacrylic acid and tert-butylperoxy-2-ethylhexa The mixture with 3.6 g of nooate was added dropwise over 1.5 hours. After completion of the dropwise addition, the mixture was reacted at 100 ° C. for 2 hours and then cooled to obtain a resin solution. The resin was purified from the resin solution with hexane to obtain a pigment dispersant 2 having a molecular weight of 20000 and an acid value of 102 mg KOH / g.

1-3. Preparation of Pigment Dispersion A In 80 g of ion-exchanged water, 2 g of the pigment dispersant 1 obtained above and 0.2 g of N, N-dimethylaminoethanol are dissolved, and PR122 (CI Pigment Red 122) is prepared. A pigment dispersion A was obtained by adding 15.0 g and 0.05 g of an antifoaming agent ("Surfynol 104PG" manufactured by Air Products Co., Ltd.), and dispersing with a zirconia gel using a paint shaker.

1-4. Preparation of pigment dispersion B To 80 g of ion-exchanged water, add 3 g of pigment dispersant SOLSPERSE 47000 (mass average molecular weight 280000, acid value 20 mg KOH / g, manufactured by Lubrisol Co.), 15.0 g of PR122 and 0.05 g of Surfynol 104PG, The pigment dispersion liquid B was obtained by dispersing using zirconia beads with a paint shaker.

1-5. Preparation of Pigment Dispersion C In 80 g of ion-exchanged water, 2 g of the pigment dispersant 2 obtained above and 0.4 g of N, N-dimethylaminoethanol are dissolved, 15.0 g of PR122 and 0 of Surfynol 104 PG The pigment dispersion liquid C was obtained by adding .05 g and dispersing using zirconia beads with a paint shaker.

2. Adjustment of resin 2-1. Preparation of Resin Emulsion A A flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas inlet tube, a reflux tube and a dropping funnel is sufficiently replaced with nitrogen gas, and then a reactive surfactant (Kao Co., Ltd. product) Name: Latemul PD-104) 0.75 g, potassium persulfate 0.04 g, methacrylic acid 1 g and pure water 150 g were charged and mixed by stirring at 25 ° C. A mixture of 60 g of methyl methacrylate, 45 g of methyl acrylate, 22.5 g of styrene and 22.5 g of α-methyl-styrene was added dropwise to this to prepare a pre-emulsion. In addition, after the inside of a flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas inlet tube, a reflux tube and a dropping funnel is sufficiently replaced with nitrogen gas, a reactive surfactant (Kao Co., Ltd., trade name: Latemru) 3 g of PD-104, 0.01 g of potassium persulfate and 200 g of pure water were stirred and mixed at 70 ° C. Thereafter, the prepared pre-emulsion was dropped into the flask over 3 hours. After heat aging at 70 ° C. for 3 hours, it is cooled, adjusted to pH 8 with N, N-dimethylethanolamine, filtered through # 150 mesh (made by Japan Textile), solid content 30 mass%, 500 g Resin emulsion A (glass transition temperature: 76 ° C., acid value: 4 mg KOH / g, average particle size: 90 nm).

2-2. Preparation of Resin Emulsion B The inside of a flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel is sufficiently replaced with nitrogen gas, and then a reactive surfactant (Kao Co., Ltd. product) Name: Latemul PD-104) 0.75 g, potassium persulfate 0.04 g, methacrylic acid 6.0 g, and 150 g of pure water were charged and mixed by stirring at 25 ° C. A mixture of 111.0 g of methyl methacrylate, 18 g of 2-ethylhexyl acrylate and 15 g of butyl acrylate was added dropwise thereto to prepare a pre-emulsion. In addition, after the inside of a flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas inlet tube, a reflux tube and a dropping funnel is sufficiently replaced with nitrogen gas, a reactive surfactant (Kao Co., Ltd., trade name: Latemru) 3 g of PD-104, 0.01 g of potassium persulfate and 200 g of pure water were stirred and mixed at 70 ° C. Thereafter, the prepared pre-emulsion was dropped into the flask over 3 hours. Heat aged at 70 ° C. for 3 hours, cool, adjust to pH 8 with N, N-dimethylethanolamine, filter with # 150 mesh (made by Japan Textiles), 500 g of resin emulsion B (solid 30 mass%, a glass transition temperature of 64 ° C., an acid value of 7 mg KOH / g, and an average particle size of 120 nm) were obtained.

2-3. Preparation of water-soluble resin A The inside of a flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel was sufficiently replaced with nitrogen gas, 100 g of methyl ethyl ketone was added, and the mixture was heated to 75 ° C.
Thereto, a mixture of 50 g of butyl methacrylate, 20 g of 2-hydroxyethyl methacrylate, 15 g of acrylic acid, 15 g of maleic anhydride and 50 g of methyl ethyl ketone was dropped and heated to reflux. After cooling, methyl ethyl ketone is removed, and the pH is adjusted to 8 with ion-exchanged water and N, N-dimethylethanolamine. Water-soluble resin A (mass average molecular weight 70,000, acid value 290 mg KOH / g, solid content 30 mass% Got).

3. Preparation of Ink The ink composition of Table 1 was prepared using a pigment dispersion, a resin emulsion, a water-soluble solvent, a surfactant, and ion-exchanged water.

  In the table, surfactant A means polyether-modified polysiloxane (polysiloxane surfactant).

  In the table, surfactant B means polyoxyethylene fluorinated alkyl ether (fluorinated surfactant).

  In the table, surfactant C means polyoxyethylene lauryl ether (polyoxyalkylene alkyl ether).

  In the table, surfactant D means alkyl sulfate triethanolamine.

  In the table, surfactant E means polyoxyethylene lauryl ether sodium acetate.

<Evaluation>
[Water resistance evaluation test]
Printing was performed on the ink compositions of Examples and Comparative Examples, and evaluation of each item was performed. Specifically, a piezo-type inkjet printer (Seiko Epson PX-105) (hereinafter referred to as Printer A) on IMAGin JT5829R (polyvinyl chloride film; made by MACtac), and a thermal-type inkjet printer (Canon iP7230) (Hereinafter referred to as Printer B), solid printing with a printing rate of 100% was performed, and the test piece dried at 100 ° C. for 3 minutes was wiped with a cotton swab soaked with ion exchange water, and the printed matter was visually confirmed. A result is shown in Table 1 (In Table 1, it describes with "water resistance".).

Evaluation criteria were as follows. A and B are the actual use range.
A: There was no change in the printed matter.
B: The color of the print was slightly reduced.
C: The color of the printed matter was clearly reduced.

[Metal member appropriate evaluation]
The metal member suitability test was done about the ink composition of an Example and a comparative example. Specifically, a metal (stainless steel) piece of 10 mm × 20 mm × 0.05 mm was immersed in each of the ink compositions of Examples and Comparative Examples, and left at 60 ° C. for 4 weeks to evaluate the state change. A result is shown in Table 1 (In Table 1, it describes with "metal member appropriateness.").

Evaluation criteria were as follows. A and B are the actual use range.
A: There was almost no change in appearance.
B: A slight change in appearance was observed but no corrosion was observed.
C: Appearance change and corrosion were clearly recognized.

[Continuous discharge evaluation 1]
The ink compositions of Examples and Comparative Examples were filled in a piezo-type ink jet printer (PX-105 manufactured by Seiko Epson Corporation), continuous printing was performed for 3 hours, and the number of curved or non-ejection nozzles was confirmed. A result is shown in Table 1 (In Table 1, it describes with "continuous discharge property 1".).

Evaluation criteria were as follows. A and B are the actual use range.
A: The number of curved or non-ejection nozzles is less than 1% of all the nozzles.
B: The number of curved or non-ejection nozzles is 1% or more and less than 3% of all the nozzles.
C: The number of curved or non-ejection nozzles is 3% or more in all the nozzles.

[Continuous discharge evaluation 2]
The ink compositions of Examples and Comparative Examples were filled in a thermal type ink jet printer (iP 7230 manufactured by Canon Inc.), continuous printing was performed for 3 hours, and the number of nozzles for bending and non-ejection was confirmed. A result is shown in Table 1 (In Table 1, it describes with "continuous discharge property 2".).

Evaluation criteria were as follows. A and B are the actual use range.
A: The number of curved or non-ejection nozzles is less than 1% of all the nozzles.
B: The number of curved or non-ejection nozzles is 1% or more and less than 3% of all the nozzles.
C: The number of curved or non-ejection nozzles is 3% or more in all the nozzles.
[Intermittence discharge evaluation]
The ink compositions of Examples and Comparative Examples are filled in a piezo inkjet printer (PX-105 manufactured by Seiko Epson), and the ink composition is discharged from all the nozzles at a discharge speed of 10 m / sec, and then left for 1 hour did. Thereafter, the ink composition was ejected again at the same ejection speed from all the nozzles. Thereafter, the presence or absence of the non-ejection nozzle was visually observed and evaluated according to the following criteria. A result is shown in Table 1 (In Table 1, it describes with "intermittent dischargeability.").

Evaluation criteria were as follows. A and B are the actual use range.
A: There is no non-ejection nozzle.
B: There is a non-ejection nozzle, but all nozzles are ejected immediately by cleaning.
C: There is a non-ejection nozzle, and there is a nozzle that does not recover even after cleaning.

  From Table 1, it was confirmed that the ink compositions of Examples 1 to 8 have good metal member suitability. From the above, even if the ink composition of the present invention is an ink composition containing water as a main component, the ink composition of the present invention can suppress the deposition of the precipitate of each component contained in the ink composition and the corrosion of the metal member. It was found that the ink composition had high stability.

  Further, it is confirmed from Table 1 that the ink compositions of Examples 1 to 8 have good continuous dischargeability and intermittent dischargeability in a piezoelectric inkjet recording apparatus in addition to suppressing the corrosion of the metal members described above. The From the above, even when the ink composition of the present invention is used for inkjet, the corrosion of the inkjet nozzle and head is prevented, and the deposition of the deposit causes the ink composition to be stably discharged. It has been found that the ink composition can suppress the decrease in the viscosity.

Claims (6)

Contains a solvent containing water and an organic solvent, a resin, a coloring material, and a surfactant,
The content of the water is 50 parts by mass or more in 100 parts by mass of the ink composition,
The organic solvent contains 80 parts by mass or more of a water-soluble organic solvent having a boiling point of 120 ° C. or more and 250 ° C. or less in 100 parts by mass of the organic solvent,
The total content of the resin and the coloring material is 20 parts by mass or less in 100 parts by mass of the ink composition,
An ink composition having a pH of 6.0 to 9.0 and a conductivity of 2000 μS / cm or less.   The ink composition according to claim 1, wherein the surfactant comprises at least one surfactant selected from the group consisting of polyoxyalkylene alkyl ether, fluorosurfactant, and polysiloxane surfactant. .   The ink composition according to claim 1, wherein a content of the surfactant is 1 part by mass or less in 100 parts by mass of the ink composition.   The ink composition according to any one of claims 1 to 3, which is used in an ink jet system.   The inkjet recording method which discharges the ink composition in any one of Claim 1 to 4 on the surface of a base material by an inkjet system.   The manufacturing method of the printed matter including the process of discharging the ink composition in any one of Claim 1 to 4 on the surface of a base material by an inkjet system.