JP2007045888A - Water-based ink and method for producing the same, and ink cartridge, recording method, recording system and recorded product using the ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide water-based ink having excellent reliability such as ink preservability, plugging recovery and continuous printing stability, and providing highly glossy recorded product when printed on a glossy paper. <P>SOLUTION: The water-based ink contains an organic pigment and a water-insoluble polymer enabling the organic pigment to be dispersed in the ink. The water-insoluble polymer has a hydrogen bond-donating group and a hydrogen bond-accepting group. The method for producing the water-based ink, and the ink cartridge, the recording method, the recording system and the recorded product using the water-based ink are also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a water-based ink that is excellent in reliability such as ink storage stability, clogging recovery property, and continuous printing stability, and can provide a highly glossy recorded matter when printed on glossy paper, a method for producing the same, and the water-based ink The present invention relates to an ink cartridge, a recording method, a recording system, and a recorded matter.

  Conventionally, various technologies relating to water-based inks for the purpose of improving performances such as water resistance and glossiness of printed materials have been proposed and used.

  For example, in Japanese Patent Laid-Open No. 8-183920, stable ink jet jetting without sacrificing the features of a resin-dispersed ink excellent in print quality, water resistance and light resistance, excellent in dispersion stability, and without nozzle clogging. For the purpose of enabling the characteristics, from a colorant encapsulated in a self-water dispersible resin in which the acid value is 50 or more and 280 or less and 60 mol% or more of the acid groups are neutralized by an alkaline neutralizing agent There has been proposed an aqueous ink for inkjet recording in which colored resin particles (dye pigment particles) are dispersed (Patent Document 1).

  According to claim 10 of Patent Document 1, a self-water dispersible resin (A) in which at least a part of acid groups of the synthetic resin (a) having an acid value of 50 or more and 280 or less is neutralized with a base (b). ) Is mixed with a colored resin solution in which the colorant (B) is dispersed or dissolved in an organic solvent solution and an aqueous medium (C) containing water as an essential component, and phase inversion emulsification is performed, and the colorant (B) is added to the organic solvent solution. Disclosed is a method for producing an aqueous ink for inkjet recording, in which colored resin particles encapsulated with a resin (A) are dispersed in an aqueous medium (C) and then the organic solvent is removed from the obtained aqueous dispersion. .

  Japanese Patent Application Laid-Open No. 10-46082 proposes a water-based ink comprising a suspension of a polyester polyamide adsorbed with a dye or pigment for the purpose of improving the water resistance and fixability of printed matter, and describes phase inversion emulsification. (Patent Document 2).

  JP-A-2005-41994 discloses a pigment for the purpose of providing a water-based ink for ink-jet recording that is excellent in dispersion stability, can impart high glossiness and high print density, and a water-dispersion for ink-jet recording used therein. An aqueous dispersion of a water-insoluble vinyl polymer contained, wherein the water-insoluble vinyl polymer is obtained by polymerizing a monomer component containing a nonionic (meth) acrylamide monomer, and an aqueous dispersion for ink jet recording An aqueous ink for ink jet recording containing an aqueous dispersion has been proposed (Patent Document 3).

However, the above method still has problems in reliability such as ink storage stability, clogging recovery ability, and continuous printing stability, and when printed on glossy paper, the gloss is low and insufficient.
JP-A-8-183920 Japanese Patent Laid-Open No. 10-46082 Japanese Patent Laid-Open No. 2005-41994

  Therefore, the present invention has an object to provide a water-based ink that is excellent in reliability such as ink storage stability, clogging recovery property, and continuous printing stability, and can provide a high-gloss recording when printed on glossy paper. One of them.

  Another object of the present invention is to provide a method for producing a water-based ink having the above performance, an ink cartridge using the water-based ink, a recording method, a recording system, and a recorded matter.

The present invention relates to the following 1. By providing the invention, one of the above objects is achieved.
1. An aqueous ink comprising an organic pigment and a water-insoluble polymer capable of dispersing the organic pigment in the ink, wherein the water-insoluble polymer has a hydrogen bond donating group and a hydrogen bond accepting group.

The present invention also provides the following 2. -18. This invention is provided.
2. 2. The water-based ink according to 1 above, wherein the organic pigment is a quinacridone pigment.

  3. After dispersing a mixture containing at least an organic pigment, a water-insoluble polymer, and an organic solvent, the mixture is converted into an aqueous system by (1) adding water to the mixture, or (2) adding the mixture to water. 3. The water-based ink according to the above 1 or 2, which is prepared.

  4). 4. The water-based ink according to any one of 1 to 3, wherein the water-insoluble polymer is a water-insoluble vinyl polymer.

  5. 5. The water-based ink according to any one of 1 to 4, wherein the water-insoluble polymer contains 3 to 15% by weight of hydrogen bond donating groups in monomer units.

  6). 6. The water-based ink according to any one of 1 to 5, wherein the hydrogen bond donating group in the water-insoluble polymer is at least one selected from an amide group, a hydroxyl group, and an amino group.

  7). 6. The water-based ink according to any one of 1 to 5, wherein the hydrogen bond donating group in the water-insoluble polymer is an amide group derived from acrylamide or methacrylamide.

8). The acrylamide or methacrylamide is represented by the formula 1:
CH = C (-R < ¹ >)-C (= O) -N (H) -R < ² >.
(R ¹ represents a hydrogen atom or a methyl group, and R ² represents a substituted or unsubstituted alkyl group.)
8. The water-based ink as described in 7 above.

  9. 9. The water-based ink according to any one of 1 to 8, wherein the hydrogen bond accepting group in the water-insoluble polymer is a carbonyl group.

  10. 10. The water-based ink according to 9, wherein the carbonyl group is a carbonyl group derived from a carboxylic acid or a carboxylic acid derivative.

  11. The water-based ink according to any one of 1 to 10, wherein the water-insoluble polymer has an aromatic ring and a salt-forming group.

  12 The water-based ink according to any one of 1 to 11, wherein the water-insoluble polymer has a weight average molecular weight of 30,000 to 150,000.

  13. The aqueous ink according to any one of 1 to 12 above, which is for inkjet.

  14 A method for producing a water-based ink, wherein a mixture containing at least an organic pigment, a water-insoluble polymer, and an organic solvent is dispersed, and (1) water is added to the mixture, or (2) the mixture is added to water.

  15. An ink cartridge containing the water-based ink according to any one of 1 to 13 above.

  16. A recording method for forming an image using the water-based ink according to any one of 1 to 13 above.

  17. A recording system for forming an image using the water-based ink according to any one of 1 to 13 above.

  18. A recorded matter in which an image is formed using the water-based ink according to any one of 1 to 13 above.

  ADVANTAGE OF THE INVENTION According to this invention, the water-based ink which is excellent in reliability, such as ink storage stability, clogging recovery | restoration property, continuous printing stability, and can provide a highly glossy recorded matter when printing on glossy paper is provided.

  Further, according to the present invention, there are provided a method for producing a water-based ink that exhibits the above-described effects, an ink cartridge using the water-based ink, a recording method, a recording system, and a recorded matter.

  Hereinafter, the present invention will be described based on preferred embodiments thereof.

As described above, the water-based ink of the present invention includes an organic pigment and a water-insoluble polymer that can disperse the organic pigment in the ink, and the water-insoluble polymer has a hydrogen bond donating group and a hydrogen bond accepting group. A water-based ink composition. In the present invention, the hydrogen bond donating group refers to a functional group having a hydrogen bond donating hydrogen. A hydrogen bond accepting group refers to a functional group that can hydrogen bond with other molecules having a donor hydrogen.
Since the water-based ink of the present invention has such a configuration, it has excellent reliability such as ink storage stability, clogging recovery property, and continuous printing stability, and can provide a highly glossy recorded material when printed on glossy paper. it can.

The organic pigment used in the present invention is not particularly limited. For example, azo pigment, disazo pigment, phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, dioxazine pigment, perylene pigment, perinone pigment, thioindigo pigment, anthraquinone pigment, quinophthalone And pigments.
Of these, quinacridone pigments are preferred because of the ease of generating hydrogen bonds with the water-insoluble polymer used in the water-based ink of the present invention and, in turn, the effect of improving reliability.

  Specific examples of organic pigments include C.I. I. Pigment red 122, 202, 209, C.I. I. Pigment violet 19 and the like. I. Pigment red 122, and C.I. I. Pigment Violet 19 is preferred.

  The water-insoluble polymer used in the present invention can disperse the organic pigment in water-based ink, and has a hydrogen bond donating group and a hydrogen bond accepting group. In the present invention, the water-insoluble polymer refers to a polymer that does not dissolve in water by 2% by weight or more.

  Examples of the water-insoluble polymer include water-insoluble vinyl polymers, ester polymers, urethane polymers, and the like. Among these, a water-insoluble vinyl polymer (water-insoluble vinyl polymer) is preferable because of the large number of monomer types that can be used.

Examples of the hydrogen bond donating group possessed by the water-insoluble polymer include an amide group, a hydroxyl group, and an amino group. The water-insoluble polymer can contain one or more of these hydrogen bond donating groups.
Among these, an amide group is particularly preferable, and an amide group derived from acrylamide or methacrylamide is more preferable. Further, acrylamide or methacrylamide may be represented by the formula 1:
CH = C (-R < ¹ >)-C (= O) -N (H) -R < ² >.
(R ¹ represents a hydrogen atom or a methyl group, and R ² represents a substituted or unsubstituted alkyl group.)
It is more preferable that

  Water-insoluble polymers include: [1] 3 to 15% by weight of monomer having a hydrogen bond donating group, [2] 10 to 80% by weight of monomer having a hydrogen bond accepting group, and [3] 10 to 80 aromatic ring-containing monomer. Wt%, [4] 3-30 wt% of a salt-forming group-containing monomer, [5] monomer having the hydrogen bond-donating group, monomer having the hydrogen bond-accepting group, aromatic ring-containing monomer, and salt-forming group-containing A polymer obtained by polymerizing a monomer composition containing 10 to 80% by weight of a monomer copolymerizable with the monomer, particularly a water-insoluble vinyl polymer is preferably used.

  Examples of the monomer having a hydrogen bond donating group include unsaturated amides, hydroxyl group-containing vinyl compounds, aminoalkyl acrylates or aminoalkyl methacrylates, N-aminoalkyl acrylamides or N-aminoalkyl methacrylamides.

  Examples of the unsaturated amides include acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N-propylacrylamide, N-propylmethacrylamide, N-isopropylacrylamide. N-isopropylmethacrylamide, Nt-butylacrylamide, Nt-butylmethacrylamide, Nt-hexylacrylamide, Nt-hexylmethacrylamide, Nt-hexylacrylamide, Nt-hexylmethacrylate Amide, Nt-octylacrylamide, Nt-octylmethacrylamide, N- (1-methylundecyl) acrylamide, N- (1-methylundecyl) methacrylamide, N-isobornylacrylamido N-isobornylmethacrylamide, N-norbornylacrylamide, N-norbornylmethacrylamide, N-benzylacrylamide, N-benzylmethacrylamide, N- (1,5-dimethyl-1-ethyl) hexylacrylamide N- (1,5-dimethyl-1-ethyl) hexyl methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-cyclohexyl acrylamide, N-cyclohexyl methacrylamide, N-methylol acrylamide, maleic amide, etc. Can be mentioned.

  Examples of the hydroxyl group-containing vinyl compounds include 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate.

  Examples of the aminoalkyl acrylate or aminoalkyl methacrylate include N-methylaminoethyl acrylate, N-methylaminoethyl methacrylate, N-methylaminopropyl acrylate, N-methylaminopropyl methacrylate, Nt-butylaminoethyl acrylate, N -T-butylaminoethyl methacrylate and the like.

  Examples of the N-aminoalkylacrylamide or N-aminoalkylmethacrylamide include N-methylaminopropylacrylamide, N-methylaminopropylmethacrylamide, N-methylaminoethylacrylamide, N-methylaminoethylmethacrylamide, and the like. .

  The unsaturated amides, hydroxyl group-containing vinyl compounds, aminoalkyl acrylates or aminoalkyl methacrylates, N-aminoalkyl acrylamides or N-aminoalkyl methacrylamides also have a hydrogen bond accepting group. That is, the NH portion, hydroxyl group, and amino group of the amide group function as a hydrogen bond donating group, and the CO portion of the amide group and the CO portion of the ester group function as a hydrogen bond accepting group.

  As for the content of hydrogen bond donating groups in the water-insoluble polymer, it is preferable that 3 to 15% by weight of monomers having hydrogen bond donating groups are contained in the monomer composition when forming the polymer, more preferably 5%. ~ 12% by weight. If it is less than 3% by weight, the effect of improving the reliability such as ink storage stability, clogging recovery property, and continuous printing stability is poor, and the gloss when printed on glossy paper may be low. If it exceeds 15% by weight, reliability such as ink storage stability, clogging recovery ability, and continuous printing stability tends to be lowered.

Examples of the hydrogen bond accepting group include a group having a carbonyl bond (carbonyl group). Examples of the compound having a carbonyl group include ketones, aldehydes, carboxylic acids, and carboxylic acid derivatives. Of these, carboxylic acids and carboxylic acid derivatives are preferred. That is, as a carbonyl group suitable as a hydrogen bond accepting group, ink storage stability, clogging recovery property, reliability such as continuous printing stability, and the ability to provide a highly glossy record when printed on glossy paper. And carbonyl groups derived from carboxylic acids and carboxylic acid derivatives are preferred.
Examples of the carboxylic acid derivative include esters, amides, acid halogen compounds, and acid anhydrides, and esters and amides are more preferable.
Regarding hydrogen bond accepting groups, it is better to use a monomer having a hydrogen bond accepting group alone than a monomer having both a hydrogen bond donating group and a hydrogen bond accepting group, ink storage stability, clogging recovery, and continuous printing. It is preferable in terms of reliability such as stability, and when a glossy paper is printed, a highly glossy recorded matter can be provided.

  In addition to the unsaturated amides, the hydroxyl group-containing vinyl compounds, the aminoalkyl acrylates or aminoalkyl methacrylates, the N-aminoalkyl acrylamides or the N-aminoalkyl methacrylamides, a monomer having a hydrogen bond accepting group, Examples include acrylates, methacrylates, and unsaturated carboxylic acids.

  Examples of the acrylates include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, dodecyl acrylate, Examples thereof include alkyl esters of 1 to 12 carbon atoms of acrylic acid such as octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, and benzyl acrylate.

  Examples of the methacrylates include ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, Examples thereof include alkyl esters having 1 to 12 carbon atoms of methacrylic acid such as cyclohexyl methacrylate, phenyl methacrylate, and benzyl methacrylate.

  Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, acrylic anhydride, methacrylic anhydride, maleic anhydride, itaconic anhydride, and fumaric anhydride.

  As for the content of hydrogen bond accepting groups of the water-insoluble polymer, it is preferable that 10-80% by weight of monomers having hydrogen bond accepting groups are contained in the monomer composition when forming the polymer, more preferably 15%. ~ 70 wt%.

  The water-insoluble polymer improves the dispersion stability of the colorant, and thus has an aromatic ring and a salt-forming group in terms of reliability such as ink storage stability, clogging recovery property, and continuous printing stability. preferable. The aromatic ring and the salt-forming group can be obtained by using an aromatic ring-containing monomer and a salt-forming group-containing monomer when forming the polymer.

Aromatic ring-containing monomers include aromatic vinyl compounds.
Examples of the aromatic vinyl compounds include styrene, 2-methylstyrene, t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene, and divinylbenzene.

  About content of the aromatic ring which a water-insoluble polymer has, it is preferable that 10-80 weight% of aromatic ring containing monomers are contained in the monomer composition at the time of forming this polymer, More preferably, it is 15-70 weight%. is there. If it is less than 10% by weight, water resistance and fixability may be insufficient. If it exceeds 80% by weight, there is a risk that problems due to a decrease in the amount of other monomers used tend to occur.

  As the salt-forming group-containing monomer, an anionic monomer is preferable. An anionic monomer can be used individually or in mixture of 2 or more types, respectively.

  Examples of the anionic monomer include one or more selected from the group consisting of an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer.

  Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinate. These can be used alone or in admixture of two or more.

  Examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylic acid ester, bis- (3-sulfopropyl) -itaconic acid ester, and the like. Can be mentioned. These can be used alone or in admixture of two or more.

  Examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acrylic acid. And leuoxyethyl phosphate. These can be used alone or in admixture of two or more.

  Among the anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of ink viscosity and dischargeability.

  When the water-insoluble polymer has a salt-forming group, the content of the salt-forming group is preferably 3 to 30% by weight of the salt-forming group-containing monomer in the monomer composition when forming the polymer. More preferably, it is 5 to 25% by weight. If it is less than 3% by weight, reliability such as ink storage stability, clogging recovery ability, and continuous printing stability may be lowered. If it exceeds 30% by weight, the viscosity of the ink increases, and there is a risk that problems due to a decrease in the amount of other components used during ink blending tend to occur.

  Examples of the monomer having a hydrogen bond donating group, the monomer having a hydrogen bond accepting group, the aromatic ring-containing monomer, and the salt-forming group-containing monomer include vinyl esters, vinylidene halides, and diacrylates. And dimethacrylates.

  Examples of the vinyl esters include vinyl acetate and vinyl propionate.

  Examples of the vinylidene halides include vinylidene chloride and vinylidene fluoride.

  Examples of the diacrylates include polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, and the like.

  Examples of the dimethacrylates include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6 -Hexanediol dimethacrylate, neopentyl glycol dimethacrylate and the like.

Other monomers include trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane triacrylate, tetramethylolmethane tetraacrylate, allyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, vinyl chloride, Vinyl ether, vinyl ketone, vinyl amide, chloroprene, ethylene, propylene, isoprene, butadiene, vinyl pyrrolidone, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, acrylonitrile, methacrylonitrile, isopropenyl- α, α-dimethylbenzyl isocyanate, ants Examples include lumercaptan.
As said other monomer, only 1 type may be sufficient and it can use 2 or more types together.

  In the monomer composition for forming the water-insoluble polymer, the monomer having the hydrogen bond donating group, the monomer having the hydrogen bond accepting group, the monomer containing the aromatic ring and the monomer capable of copolymerizing with the salt-forming group containing monomer are: 10 to 80% by weight, and more preferably 15 to 70% by weight. If it is less than 10% by weight, the water resistance and fixability may be lowered. If it exceeds 80% by weight, there is a risk that problems due to a decrease in the amount of other monomers used tend to occur.

  The weight average molecular weight of the water-insoluble polymer is preferably 30,000 to 150,000 in terms of glossiness and printing density. The weight average molecular weight of the polymer can be controlled by a conventional operation of adding a chain transfer agent such as mercaptan.

  The weight average molecular weight of the polymer was determined by drying a portion of the resulting polymer solution at 105 ° C. under reduced pressure for 2 hours and removing the solvent, and using polystyrene as the standard substance and 60 mmol / L phosphoric acid as the solvent. And 50 per cent by gel permeation chromatography using dimethylformamide containing lithium bromide.

The water-insoluble polymer can be synthesized, for example, by polymerizing the monomer composition by the following method.
That is, the water-insoluble polymer is produced by polymerizing the monomer composition by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable.

  The solvent used in the solution polymerization method is preferably a polar organic solvent. When the polar organic solvent is miscible with water, it can be used by mixing with water.

  Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and the like. Among these, methanol, ethanol, acetone, methyl ethyl ketone, or a mixed solution of these with water is preferable.

In the polymerization of the monomer composition, a radical polymerization initiator can be used.
Examples of the radical polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2′-azobisbutyrate, 2, Azo compounds such as 2′-azobis (2-methylbutyronitrile), 1,1′-azobis (1-cyclohexanecarbonitrile); t-butyl peroxyoctate, di-t-butyl peroxide, dibenzoyl oxide, etc. Organic peroxides can be used.

  The addition amount of the polymerization initiator per 1 mol of the monomer composition is preferably 0.001 to 5 mol, and more preferably 0.01 to 2 mol.

In the polymerization of the monomer composition, a polymerization chain transfer agent may be added in addition to the radical polymerization initiator.
Examples of the polymerization chain transfer agent include mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-tetradecyl mercaptan and 2-mercaptoethanol; xanthogen disulfides such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide; Thiuram disulfides such as methylthiuram disulfide and tetrabutylthiuram disulfide; Halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; Hydrocarbons such as pentaphenylethane; Acrolein, methacrolein, allyl alcohol, 2-ethylhexylthio Glycolate, terbinolene, α-terpinene, γ-terpinene, dipentene, α-methylstyrene dimer, 9,10-dihydroanthracene, 1, - dihydronaphthalene, indene, 1,4-cyclohexadiene unsaturated cyclic hydrocarbon compounds of a diene and the like; 2,5-unsaturated heterocyclic compounds dihydrofuran like can be used. These polymerization chain transfer agents can be used alone or in admixture of two or more.

  Since the polymerization conditions of the monomer composition vary depending on the radical polymerization initiator, the monomer, the type of the solvent, and the like, it cannot be determined unconditionally. Usually, the polymerization temperature is preferably 30 to 100 ° C, more preferably 50 to 80 ° C, and the polymerization time is preferably 1 to 20 hours. The polymerization atmosphere is preferably an inert gas atmosphere such as nitrogen gas.

  After completion of the polymerization reaction, the produced water-insoluble polymer is isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained water-insoluble polymer can be purified by repeating reprecipitation or removing unreacted monomers by membrane separation, chromatographic method, extraction method or the like.

  The water-based ink of the present invention can be prepared using a pigment dispersion in which the organic pigment is dispersed with the water-insoluble polymer. Hereinafter, a method for obtaining such a pigment dispersion will be described.

As a method for producing a pigment dispersion that can be used in the present invention, a physical mechanical method such as a forced emulsification method for forcibly obtaining a pigment dispersion by mechanical stirring force or shearing force, a coacervation method, There are two methods including chemical methods such as interfacial polymerization method and in-situ method.
However, the particle diameter (particle diameter) of the organic pigment contained in the pigment dispersion obtained by these conventional methods is large. For this reason, when water-based ink is produced using this pigment dispersion, it is not always satisfactory in definition, color rendering, transparency or color density, and it is necessary to produce a finer pigment dispersion. There is.

As a method for producing a pigment dispersion used in the water-based ink of the present invention, basically, a mixture (composite or complex) of a water-insoluble polymer and an organic pigment is used as an organic solvent phase. A method in which water is added or the organic solvent phase is charged in water and phase inversion emulsification (hereinafter referred to as phase inversion method) is preferred. That is, after dispersing a mixture containing at least an organic pigment, a water-insoluble polymer, and an organic solvent, (1) water is added to the mixture, or (2) the mixture is added to water. It is preferable to manufacture.
By these methods, the desired fine pigment dispersion can be produced.

  Therefore, the water-based ink of the present invention is obtained by dispersing a mixture containing at least an organic pigment, a water-insoluble polymer, and an organic solvent, and then (1) adding water to the mixture, or (2) the mixture in water. It is preferable that it is formed by converting to an aqueous system by adding.

The pigment dispersion by the phase inversion method is produced as follows.
In the phase inversion method, the organic solvent used when the mixture (composite or complex) of the water-insoluble polymer and the pigment is used as the organic solvent phase is not particularly limited, and can dissolve the water-insoluble polymer. As long as it is, any one can be used, but from the ease of solvent removal during production, ketone solvents, ester solvents, alcohol solvents, aromatic hydrocarbon solvents, ether solvents, aliphatic hydrocarbon systems A solvent having a low boiling point such as a solvent or a halogenated aliphatic hydrocarbon solvent is preferred.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of the ester solvent include ethyl acetate. Examples of the alcohol solvent include methanol, ethanol, isopropanol, n-butanol, tertiary butanol, isobutanol, diacetone alcohol and the like. Examples of the aromatic hydrocarbon solvent include benzene and toluene. Examples of the ether solvent include dibutyl ether, tetrahydrofuran, dioxane and the like. Examples of the aliphatic hydrocarbon solvent include heptane, hexane, cyclohexane and the like. Examples of the halogenated aliphatic hydrocarbon solvent include methylene chloride, 1,1,1-trichloroethane, chloroform, carbon tetrachloride, 1,2-dichloroethane and the like.

The ratio of the water-insoluble polymer is preferably in the range of 25 to 190 parts by weight, particularly preferably in the range of 30 to 150 parts by weight with respect to 100 parts by weight of the pigment.
In particular, it is desirable for a mixture (composite or complex) that is an organic solvent phase to disperse the pigment finely and uniformly in the organic solvent phase in which the water-insoluble polymer is dissolved without any aggregation. Although it is stabilized, it is by no means limited to this.

  The method for stabilizing the dispersion of the mixture is not particularly limited, but only typical ones among them are exemplified. (1) A powder pigment is converted into a bead mill, a roll mill or a sand mill. Or a method of finely dispersing in an organic solvent phase in which a water-insoluble polymer is dissolved using various dispersers such as, or (2) a wet cake after synthesis of a pigment, that is, water A method of finely dispersing a pigment in a state in which the pigment is dispersed in a water-insoluble polymer before neutralization by performing flashing using various dispersers such as a kneader. Can be mentioned. In these dispersion methods, in order to obtain ultrafine particles, a bead mill dispersion or flushing method is more preferable.

  In particular, since the latter method uses a wet cake, it does not require a drying step of organic pigments, which saves energy and does not cause any strong aggregation that occurs during the drying step. It is highly useful.

In order to facilitate phase inversion emulsification and to simplify the solvent removal operation, it is desirable to keep the amount of solvent used in the mixture as low as possible.
By injecting water into the organic solvent phase of the mixture or by injecting the organic solvent phase into water, phase inversion emulsification is performed. As the method, either the organic solvent phase or water is used. The target pigment dispersion can be formed instantaneously by slowly throwing the other into it while stirring moderately.

  In such agitation, the type and speed of the stirrer do not significantly affect the size of the formed particles, and therefore the type and speed of the stirrer are not particularly limited.

  In such a production method, it is possible to make a sufficiently fine pigment dispersion even with the above procedure, but as a method of making a finer one, phase inversion emulsification is performed while applying ultrasonic waves to the organic phase. That is. The frequency of the ultrasonic wave is not particularly limited, but is preferably 10 to 200 KHz.

  Further, in order to neutralize the water-insoluble polymer, it is necessary to previously dissolve the neutralizing bases in the organic solvent phase or the aqueous phase in a necessary amount. In particular, it is more preferable to dissolve the bases in the aqueous phase in consideration of the aggregation of the pigment in the organic solvent phase.

  Examples of the neutralizing agent include tertiary amines such as trimethylamine and triethylamine, ammonia, sodium hydroxide, potassium hydroxide and the like.

  There is no particular limitation on the degree of neutralization. Usually, it is preferable that the obtained aqueous dispersion has neutral liquidity, for example, pH of 4.5 to 10.

  Next, the pigment dispersion that has been subjected to the phase inversion emulsification treatment may be diluted to a desired solid content concentration and further subjected to a dispersion treatment. In the dispersion treatment, a ball mill, a roll mill, a bead mill, a high-pressure homogenizer, a high-speed stirring type disperser, or the like can be used. Among these, a high-pressure homogenizer with less inorganic impurities is preferable. Examples of the high-pressure homogenizer include those having a chamber in which the flow path of the processing liquid is fixed and those having a homogeneous valve capable of adjusting the width of the flow path of the processing liquid. As a high-pressure homogenizer having a chamber in which the flow path of the processing solution is fixed, a microfluidizer (trade name, manufactured by Microfluidics), a nanomizer (trade name, manufactured by Nanomizer), an optimizer (manufactured by Sugino Machine, product) Name). Examples of high-pressure homogenizers that have a homogeneous valve include high-pressure homogenizers (trade name, manufactured by Lani), high-pressure homogenizers (trade name, manufactured by Mimaru Machinery Co., Ltd.), and high-pressure homogenizers (trade name, manufactured by Izumi Food Machinery Co., Ltd.). Can be mentioned. The pressure when dispersing with a high-pressure homogenizer is preferably 50 MPa or more, and more preferably 80 MPa or more because polymer particles having a desired particle diameter can be easily obtained in a short time.

  Next, the aqueous ink of the present invention having a desired concentration is obtained by removing a predetermined amount of the organic solvent and water from the pigment dispersion. The method for removing water is not particularly limited. As a method for removing the organic solvent, a vacuum distillation method, particularly a thin-film vacuum distillation method is preferable. The removal amount of the organic solvent is not particularly limited, and it is usually preferable to remove the whole amount of the organic solvent.

  After removing the solvent, coarse particles may be removed as necessary. For example, the ink obtained as described above is subjected to pressure filtration through a filter or processed by a centrifuge, and is preferably 2 μm or more, more preferably 1 μm or more, more preferably 0.5 μm or more. By removing the particles, an ink having high dispersion stability can be obtained.

  The water-based ink of the present invention can be obtained by sufficiently mixing the pigment dispersion obtained as described above in a mixed organic solvent.

  The content of the organic pigment that is the colorant in the water-based ink of the present invention is not particularly limited as long as a sufficient printing density can be obtained. From the viewpoint of imparting sufficient dischargeability and printing density, 1 to 30 weight% is preferable, 2-10 weight% is more preferable, and 4-8 weight% is still more preferable.

  The water contained in the water-based ink of the present invention is a main solvent, and it is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, and distilled water. In particular, the use of water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is preferable because it prevents mold and bacteria from being generated and allows the ink composition to be stored for a long period of time.

  The water-based ink of the present invention preferably contains a water-soluble organic compound. Examples of the water-soluble organic compound include glycerin, 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, 2- Butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, Alkanediols (polyhydric alcohols) such as 4-methyl-1,2-pentanediol; glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, (sorbitol), malto Sugars such as sugar, cellobiose, lactose, sucrose, trehalose, maltotriose; sugar alcohols; hyaluronic acids; so-called solid wetting agents such as ureas; C1-C4 such as ethanol, methanol, butanol, propanol, isopropanol Alkyl alcohols; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl Ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono -N-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol Mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, tri Glycol ethers such as ethylene glycol mono-n-butyl ether; 2-pyrrolidone, N-methyl-2 Examples include pyrrolidone, 1,3-dimethyl-2-imidazolidinone, formamide, acetamide, dimethyl sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin, sulfolane and the like, and one or more of these can be used. These water-soluble organic solvents are preferably contained in the ink composition in an amount of 10 to 50% by weight from the viewpoint of ensuring appropriate physical properties (such as viscosity) of the ink composition, printing quality, and reliability. .

  Among the water-soluble organic compounds, the gloss of the recorded matter can be improved by adding alkanediol.

  Specific examples of the alkanediol include propanediol, butanediol, pentanediol, and octanediol. Among these alkanediols, 1,2-alkanediol is preferable, and among these, 1,2-pentanediol and 1 2-hexanediol is particularly preferred.

  The addition amount of the alkanediol is preferably 0.5 to 5% by weight based on the total amount of the water-based ink.

  If necessary, the water-based ink of the present invention may further contain various known additives such as pH adjusters, surfactants, antioxidants, ultraviolet absorbers, antiseptic / antifungal agents and the like.

  Examples of the pH adjuster that can be added to the aqueous ink of the present invention include hydroxides of alkali metals such as lithium hydroxide, potassium hydroxide, and sodium hydroxide, ammonia, triethanolamine, tripropanolamine, and diethanolamine. Further, amines such as monoethanolamine can be used. If necessary, collidine, imidazole, phosphoric acid, 3- (N-morpholino) propanesulfonic acid, tris (hydroxymethyl) aminomethane, boric acid and the like can be used as a pH buffering agent.

  As the surfactant that can be added to the water-based ink of the present invention, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be contained. A nonionic surfactant is particularly preferable from the viewpoint of obtaining an ink composition with less foaming and foaming. Specific examples of nonionic surfactants include acetylene glycol surfactants, acetylene alcohol surfactants, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl Ethers such as allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene oleic acid ester, polyoxyethylene distearic acid ester , Sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene Nmonooreeto, polyoxyethylene stearate, etc. esters, silicone surface active agents dimethylpolysiloxane, other fluorine alkyl esters, fluorine-containing surfactants such as perfluoroalkyl carboxylic acid salts, and the like. Among the nonionic surfactants, acetylene glycol surfactants and acetylene alcohol surfactants are particularly preferable because they are less foamed and have excellent antifoaming performance.

  Specific examples of the acetylene glycol surfactant and the acetylene alcohol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne- 3,6-diol, 3,5-dimethyl-1-hexyne-3ol and the like can be mentioned. Examples of commercially available products include Surfynol 104, 82, 465, and 485 manufactured by Air Products, TG, Orphine STG manufactured by Nissin Chemical Co., and Olfin E1010.

  Examples of antioxidants and ultraviolet absorbers that can be added to the water-based ink of the present invention include allophanates such as allophanate and methyl allophanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret, and L-ascorbine. Acids and salts thereof, Tinuvin 328, 900, 1130, 384, 292, 123, 144, 622, 770, 292, Irgacor 252, 153, Irganox 1010, 1076, 1035, MD1024, etc. manufactured by Ciba Geigy, or lanthanide oxides, etc. Used.

  Examples of preservatives and fungicides that can be added to the aqueous ink of the present invention include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-Dibenzisothiazolin-3-one (Avecia's Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN) and the like.

  The use of the water-based ink of the present invention is not particularly limited, but it is preferably used for ink jet printing in which droplets are ejected by an ink jet method and adhered to a recording medium. In addition, the water-based ink of the present invention can be used for writing instruments such as pens and stamps.

  Further, according to the present invention, an ink cartridge provided with the above-described water-based ink is provided. With the ink cartridge of the present invention, the usability and handling of the water-based ink can be ensured.

  The present invention also provides a recording method for forming an image on a recording medium using the water-based ink described above. In one embodiment of the recording method of the present invention, the above-described aqueous ink droplets are ejected by an inkjet method, and the droplets are attached to a recording medium for printing. By implementing the recording method of the present invention, reliability such as clogging recovery and continuous printing stability can be secured, and a highly glossy recorded product can be obtained when printed on glossy paper.

  Further, according to the present invention, there is provided a recorded matter in which an image is formed on a recording medium using the above-described water-based ink. The recorded matter of the present invention is excellent in print quality and becomes highly glossy when printed on glossy paper.

  Further, according to the present invention, it is possible to provide a recording system for forming an image using the above-described water-based ink, and in particular, a recording apparatus such as an inkjet printer using the ink composition according to the above-described embodiment and other recording systems are suitable. Can be provided.

  The present invention suitably provides each of the embodiments described above, but is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and test examples of the present invention. However, the present invention is not limited to the examples.

[Synthesis of resin]
In the reaction vessel, 20 parts by weight of methyl ethyl ketone, 10% by weight of each blending amount (parts by weight) of each monomer of Production Example Nos. 1 to 7 shown in Table 1, and 2 of each blending amount shown in Table 1 -Mercaptoethanol (polymerization chain transfer agent) was added and mixed, and nitrogen gas substitution was sufficiently performed to obtain seven types of liquid mixture.

  Separately, on the other hand, the remaining 90% by weight of the blending amount (parts by weight) of each monomer shown in Table 1 was charged into the dropping funnel, and then the polymerization chain transfer agent (2 -Mercaptoethanol), 60 parts by weight of methyl ethyl ketone, and 1.2 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) are mixed and thoroughly replaced with nitrogen gas in the dropping funnel. Seven types of mixed solutions were obtained.

  Next, the mixed solution in the reaction vessel was heated to 65 ° C. with stirring in a nitrogen atmosphere, and the mixed solution in the dropping funnel was gradually dropped into the reaction vessel over 3 hours. After completion of the dropwise addition, the liquid temperature of each mixed solution was maintained at 65 ° C. for 2 hours, and then a solution in which 0.3 part by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 5 parts by weight of methyl ethyl ketone was added. In addition to each of the mixed solutions, aging was further performed at 65 ° C. for 2 hours and at 70 ° C. for 2 hours to obtain polymer solutions of Production Examples 1 to 7.

  Each part of the polymer solutions of Production Examples 1 to 7 thus obtained was isolated by drying at 105 ° C. for 2 hours under reduced pressure to remove the solvent. Polystyrene was used as a standard substance, and 60 mmol / The weight average molecular weight of the polymer was measured by gel permeation chromatography using L phosphoric acid and 50 mmol / L lithium bromide-containing dimethylformamide.

  Table 1 shows the weight average molecular weights of the obtained vinyl polymers of Production Examples 1 to 7 together with the raw materials of the respective polymers and the blending ratios represented by weight percent thereof.

[Method for Producing Pigment Dispersion Liquid Used in Examples and Comparative Examples]
○ Phase inversion emulsification method 6 parts by weight of a polymer obtained by drying each polymer solution of the above Production Examples 1 to 7 under reduced pressure was dissolved in 75.0 parts by weight of methyl ethyl ketone, and further a quinacridone pigment [C.I. I. Pigment Red 122, manufactured by Dainippon Ink & Chemicals, Inc., trade name: Fastgen Super Magenta R] 14.0 parts by weight, and 300 parts by weight of ceramic beads having an average particle diameter of 0.5 mm, After putting in a stainless steel container, the mixture was dispersed using a bead mill disperser, and then the ceramic beads were separated by filtration to prepare an organic solvent phase of the mixture.

Next, 40.0 parts by weight of the organic solvent phase of the above mixture and 0.3 part by weight of diethanolamine were placed in a polycup, mixed using a stirrer, and then the organic solvent phase was stirred while stirring the organic solvent phase. Into this, 50 parts by weight of ion-exchanged water was added dropwise over 12 minutes, followed by phase inversion emulsification to obtain a pigment dispersion.
After removing methyl ethyl ketone from the obtained pigment dispersion at 60 ° C. under reduced pressure, a part of water was further removed to obtain pigment dispersions 1 to 7 having a solid content concentration of 20% by weight.

○ Forced emulsification method Into a glass bottle with a capacity of 250 ml, 6 parts by weight of a polymer obtained by drying each polymer solution of Production Examples 1, 2, and 7 under reduced pressure, 0.7 part of dimethylethanolamine, and “Fastgen Super After adding 14 parts by weight of magenta R and adding ion-exchanged water so that the total amount becomes 70 parts by weight, 250 g of zirconia beads having an average particle diameter of 0.5 mm are added and kneaded for 4 hours using a paint shaker. went. After kneading, the zirconia beads were filtered off to obtain a pigment dispersion composed of a resin and a pigment. Further, water was added to adjust the non-volatile content to 20% by weight to obtain pigment dispersions 8, 9, and 10, respectively.

  Table 2 shows the water-insoluble vinyl polymer and the emulsification method used to prepare the obtained pigment dispersions 1 to 10, respectively.

[Preparation of water-based ink]
[Examples 1 to 8 and Comparative Examples 1 and 2]
Using each of the obtained pigment dispersions, this and each raw material shown in Table 3 were mixed at a blending ratio (% by weight) shown in Table 3 below, and the resulting mixture was mixed with a 0.5 μm filter. Filter with a 25 mL needleless syringe [made by Terumo Co., Ltd.] equipped with [acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.] to remove coarse particles. 8 and aqueous inks of Comparative Examples 1 and 2 were obtained.

〔Evaluation item〕
Each obtained water-based ink was evaluated for the following glossiness, ink storage stability, clogging recovery property, and continuous printing stability. The results were as shown in Table 4.

○ Gloss Using an inkjet printer PX-A550 (manufactured by Seiko Epson Corporation), printing was performed as follows. That is, the magenta ink cartridge for this printer (model number ICM31, manufactured by Seiko Epson Corporation) was filled with the aqueous inks of the examples and comparative examples, respectively, and PM photographic paper (trade name, manufactured by Seiko Epson Corporation, model number: KA420PSK) was printed with a solid image with gradation at a resolution of 1440 × 720 dpi to obtain a recorded matter. The obtained recorded matter was allowed to stand at room temperature for 1 day, and then the 20 ° gloss of the highest density portion was measured using a gloss meter GM-268 (manufactured by Konica Minolta). The measurement results were evaluated based on the following criteria.

A: When 20 ° gloss is 60 or more B: When 20 ° gloss is 50 or more and less than 60 C: When 20 ° gloss is 40 or more and less than 50 D: When 20 ° gloss is less than 40

Ink storage stability An aluminum pack was left in a 70 ° C. environment for 1 week with 50 g of water-based ink. After leaving, the presence or absence of foreign matter (sediment) was confirmed. Moreover, changes in physical properties (viscosity, surface tension, pH, particle diameter of resin particles) were further confirmed for those in which no foreign matter was generated. Evaluation was performed based on the following criteria.

A: No foreign matter is generated, and there is no change in physical properties.
B: No foreign matter is generated, but the physical properties slightly change.
C: Foreign matter is generated or the physical properties are remarkably changed.

○ Clogging recovery performance Using the above inkjet printer and cartridge, printing is continued for 10 minutes, and after confirming that all nozzles are ejected normally, the ink cartridge is used to accelerate the drying state at the nozzles. The recording head was removed from the head cap and left in an environment of 40 ° C. and 20% RH for one week. After leaving, the cleaning operation was repeated until all nozzles ejected at the same level as the initial stage, and the ease of recovery was evaluated according to the following criteria.

A: Recovered to the same level as the initial stage by one or two cleaning operations.
B: It recovered to the same level as the initial stage after 3 or 4 cleaning operations.
C: Recovered to the same level as the initial stage after 4 or 5 cleaning operations.
D: It does not recover after a realistic number of cleaning operations.

Continuous printing stability Solid and line patterns were continuously printed at room temperature using the cartridge and ink jet printer described above. The number of times the printer nozzle was cleaned as an operation for returning to normal printing in the case of ink dot missing or flying bending within 100 pages of printing was measured and evaluated based on the following criteria.

A: Cleaning 0 times B: Cleaning 1 or 2 times C: Cleaning 3 or 4 times D: Cleaning 5 times or more

実施例１〜８は、比較例１、及び２と比較し、光沢紙に印刷した場合、記録物がより高光沢となり、インク保存性、目詰まり回復性、連続印刷安定性等の信頼性に優れる。
転相乳化法により分散処理した実施例３、及び４は、実施例１、及び２と比較し、光沢紙に印刷した場合、記録物がより高光沢となり、インク保存性、目詰まり回復性、連続印刷安定性等の信頼性に優れる。
好ましいアクリルアミドを好ましい量使用した実施例７、及び８は、実施例３と比較し、光沢紙に印刷した場合、記録物がより高光沢となり、目詰まり回復性、連続印刷安定性に優れる。
水素結合供与基を好ましい量使用した実施例７は、実施例５、及び６と比較し、光沢紙に印刷した場合、記録物がより高光沢となり、目詰まり回復性、連続印刷安定性に優れる。

In Examples 1 to 8, compared to Comparative Examples 1 and 2, when printed on glossy paper, the recorded matter becomes more glossy, resulting in reliability such as ink storage stability, clogging recovery, and continuous printing stability. Excellent.
In Examples 3 and 4 subjected to dispersion treatment by the phase inversion emulsification method, compared to Examples 1 and 2, when printed on glossy paper, the recorded matter becomes more glossy, ink storage stability, clogging recovery property, Excellent reliability such as continuous printing stability.
In Examples 7 and 8 in which a preferable amount of acrylamide was used, compared to Example 3, when printed on glossy paper, the recorded matter had a higher gloss, excellent clogging recovery, and continuous printing stability.
In Example 7 using a preferable amount of hydrogen bond donating group, compared to Examples 5 and 6, when printed on glossy paper, the recorded matter becomes more glossy, and is excellent in clogging recovery and continuous printing stability. .

The present invention is a water-based ink that is excellent in reliability such as ink storage stability, clogging recovery property, continuous printing stability and the like, and can provide a highly glossy recorded matter when printed on glossy paper, a method for producing the water-based ink, The present invention has industrial applicability as an ink cartridge, recording method, recording system, and recorded matter using the water-based ink.

Claims (18)

  An aqueous ink comprising an organic pigment and a water-insoluble polymer capable of dispersing the organic pigment in the ink, wherein the water-insoluble polymer has a hydrogen bond donating group and a hydrogen bond accepting group.   The water-based ink according to claim 1, wherein the organic pigment is a quinacridone pigment. After dispersing a mixture containing at least an organic pigment, a water-insoluble polymer, and an organic solvent,
The water-based ink according to claim 1 or 2, wherein the water-based ink is prepared by adding water to the mixture or (2) adding the mixture to water to convert to water.   The water-based ink according to claim 1, wherein the water-insoluble polymer is a water-insoluble vinyl polymer.   The water-based ink according to any one of claims 1 to 4, wherein the water-insoluble polymer contains 3 to 15% by weight of hydrogen bond donor groups in monomer units.   The water-based ink according to any one of claims 1 to 5, wherein the hydrogen bond donating group in the water-insoluble polymer is at least one selected from an amide group, a hydroxyl group, and an amino group.   The water-based ink according to any one of claims 1 to 5, wherein the hydrogen bond donating group in the water-insoluble polymer is an amide group derived from acrylamide or methacrylamide. The acrylamide or methacrylamide is represented by the formula 1:
CH = C (-R < ¹ >)-C (= O) -N (H) -R < ² >.
(R ¹ represents a hydrogen atom or a methyl group, and R ² represents a substituted or unsubstituted alkyl group.)
The water-based ink according to claim 7 represented by:   The water-based ink according to any one of claims 1 to 8, wherein the hydrogen bond accepting group in the water-insoluble polymer is a carbonyl group.   The water-based ink according to claim 9, wherein the carbonyl group is a carbonyl group derived from a carboxylic acid or a carboxylic acid derivative.   The water-based ink according to claim 1, wherein the water-insoluble polymer has an aromatic ring and a salt-forming group.   The water-based ink according to any one of claims 1 to 11, wherein the water-insoluble polymer has a weight average molecular weight of 30,000 to 150,000.   The water-based ink according to any one of claims 1 to 12, which is used for inkjet. After dispersing a mixture containing at least an organic pigment, a water-insoluble polymer, and an organic solvent,
(1) A method for producing a water-based ink, wherein water is added to the mixture, or (2) the mixture is added to water.   An ink cartridge comprising the water-based ink according to claim 1.   A recording method for forming an image using the water-based ink according to claim 1.   A recording system for forming an image using the water-based ink according to claim 1. A recorded matter in which an image is formed using the water-based ink according to claim 1.