JP6051839B2 - Inkjet ink - Google Patents

Description

  One embodiment of the present invention relates to an inkjet ink, an ink container, an inkjet recording apparatus, a method for manufacturing a recorded matter, and a recorded matter.

  In recent years, as an image forming apparatus, an ink jet recording apparatus has become widespread because the process is simple, full-colorization is easy, and a high-resolution image can be obtained even with a simple configuration.

  An ink jet recording apparatus is an apparatus that forms an image by causing ink to fly and adhere to a recording medium by pressure generated using bubbles, piezo, electrostatic, or the like generated by heat. Applications are expanding to printing.

  Patent Document 1 discloses a quick-drying ink containing a colorant that is dispersed or dissolved in water, water, and a wetting agent, and having polymer gel microspheres that can be changed in volume by changes in proton concentration in a contracted state. ing.

  However, it is desired to improve the image density on plain paper.

  An object of one embodiment of the present invention is to provide an inkjet ink that is excellent in image density on plain paper in view of the problems of the above-described conventional technology.

  One embodiment of the present invention, in an inkjet ink, includes water, a water-soluble organic solvent, a pigment, and polymer particles, and the polymer particles have a general formula

（式中、Ｒ^１は、炭素数が１以上４以下のアルキル基である。）
で表される化合物由来の構成単位と、一般式

(In the formula, R ¹ is an alkyl group having 1 to 4 carbon atoms.)
A structural unit derived from a compound represented by the formula:

（式中、Ｒ^２は、炭素数が１又は２のアルキル基である。）
で表される化合物由来の構成単位と、一般式

(In the formula, R ² is an alkyl group having 1 or 2 carbon atoms.)
A structural unit derived from a compound represented by the formula:

（式中、Ｒ^３は、炭素数が１又は２のアルキル基であり、ｋは、重合度である。）
で表される化合物由来の構成単位を有する共重合体を含み、前記一般式（３）で表される化合物は、数平均分子量が５００以上５００００以下である。

(In the formula, R ³ is an alkyl group having 1 or 2 carbon atoms, and k is the degree of polymerization.)
In looking containing a copolymer having structural units derived from compounds represented by the compound represented by the general formula (3) has a number average molecular weight of 500 to 50,000.

  According to one embodiment of the present invention, it is possible to provide an inkjet ink that is excellent in image density on plain paper.

It is the schematic which shows an example of the manufacturing process of a polymer particle. It is a perspective view which shows an example of an inkjet recording device. It is the schematic which shows the whole structure of the inkjet recording device of FIG. FIG. 3 is a partially enlarged view of the ink jet recording apparatus of FIG. 2. FIG. 3 is a schematic diagram illustrating the ink cartridge of FIG. 2. It is a figure which shows the relationship of the median diameter with respect to pH of the dispersion liquid of the polymer particle of an Example.

  Next, the form for implementing this invention is demonstrated.

  The inkjet ink contains water, a water-soluble organic solvent, a pigment, and polymer particles.

  The polymer particle has a constitutional unit derived from the compound represented by the general formula (1), a constitutional unit derived from the compound represented by the general formula (2), and a constitution derived from the compound represented by the general formula (3). A copolymer having units.

In the general formula (1), R ¹ is preferably a methyl group or an ethyl group, and more preferably a methyl group.

In the general formula (2), R ² is preferably a methyl group or an ethyl group, and more preferably a methyl group.

In the general formula (3), R ³ is preferably a methyl group or an ethyl group, and more preferably a methyl group.

  The number average molecular weight of the compound represented by the general formula (3) is usually 500 to 50,000. When the number average molecular weight of the compound represented by the general formula (3) is 500 or more, the structural unit derived from the compound represented by the general formula (3) can be accumulated on the surface of the polymer particle. By being below, the polymerizability of the compound represented by the general formula (3) can be improved.

  In addition, the number average molecular weight of the compound represented by General formula (3) is a number average molecular weight of polyethylene glycol conversion measured by GPC.

  The polymer particles include a compound represented by the general formula (1) as a hydrophobic monomer, a compound represented by the general formula (2) as a pH sensitive monomer, and a general formula as a cationic macromonomer. It can be produced by copolymerizing the compound represented by (3) in a polar solvent. Therefore, the polymer particle has a core-shell structure comprising a structural unit derived from a hydrophobic monomer, a core mainly containing a structural unit derived from a pH-sensitive monomer, and a shell mainly containing a structural unit derived from a cationic macromonomer. Have

  FIG. 1 shows an example of a process for producing polymer particles.

  First, alkyl acrylate 1, dialkylaminoethyl methacrylate 2 and cationic macromonomer 3 are mixed (see FIG. 1 (a)). Here, the cationic macromonomer 3 is composed of a polymer 3a of 4-vinylbenzyltrialkylammonium chloride and a 4-vinylbenzyloxycarbonylmethylthio group 3b. Next, when copolymerized in a polar solvent, the copolymerization of alkyl acrylate 1 and dialkylaminoethyl methacrylate 2 partially proceeds (see FIG. 1 (b-1)), but with cationic macromonomer 3 Copolymerization also proceeds simultaneously (see FIG. 1 (b-2)). As a result, the polymer 3a of 4-vinylbenzyltrialkylammonium chloride was grafted from the thiol group of the copolymer of alkyl acrylate 1, dialkylaminoethyl methacrylate 2, and 4-vinylbenzyloxycarbonylmethanethiol. The graft copolymer is obtained. At this time, since the copolymerization is carried out in a polar medium, the structural unit derived from the hydrophobic alkyl acrylate 1 and the structural unit derived from the pH-sensitive dialkylaminoethyl methacrylate 2 are selectively accumulated on the inside, and are hydrophilic. The structural unit derived from the cationic macromonomer 3 is selectively accumulated outside (see FIG. 1C). As a result, a core composed of a structural unit derived from alkyl acrylate 1, a core 4a mainly containing a structural unit derived from dialkylaminoethyl methacrylate 2, and a shell 4b mainly containing a structural unit derived from cationic macromonomer 3 Polymer particles 4 having a shell structure are obtained (see FIG. 1 (d)).

  Since the pH of the inkjet ink is usually 8 to 11, the polymer particles are dispersed, and the inkjet ink has a low viscosity and excellent ejection stability.

  On the other hand, since the pH of plain paper is usually 4 to 7, when the ink jet ink lands on the plain paper, the ink jet ink is supplied with protons from the plain paper and shifted to the acidic side. As a result, the pH-sensitive structural unit derived from dimethylaminoethyl methacrylate 2 contained in the core 4a of the polymer particle 4 is quaternary ammonium salified, so that the core 4a swells and the particle size of the polymer particle 4 is reduced. growing. That is, the ink jet ink landed on the plain paper increases in viscosity due to the increase in the particle size of the polymer particles 4 and stops on the surface of the plain paper. Excellent image density.

  The molar ratio of the structural unit derived from the compound represented by the general formula (2) to the structural unit derived from the compound represented by the general formula (1) is from the viewpoint of image density on plain paper and ejection stability of the inkjet ink. Usually, it is 0.1-5, and it is preferable that it is 0.5-3.

  The molar ratio of the structural unit derived from the compound represented by the general formula (3) to the structural unit derived from the compound represented by the general formula (1) is from the viewpoint of image density on plain paper and ejection stability of the inkjet ink. Usually, it is 0.1-5, and it is preferable that it is 0.5-3.

  The content of the polymer particles in the inkjet ink is usually 0.05 to 2% by mass. When the content of the polymer particles in the inkjet ink is 0.05% by mass or more, the image density on plain paper can be improved, and by 2% by mass or less, the ejection stability of the inkjet ink is improved. Can be improved.

  The polymer particles preferably have a median diameter of 100 to 200 nm at pH 8 to 9 and a median diameter of 450 to 1000 nm at pH 4 to 6. Thereby, the image density on plain paper and the ejection stability of inkjet ink can be improved.

  The median diameter of the polymer particles can be measured using Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.).

  As the pigment, either an organic pigment or an inorganic pigment can be used, and two or more kinds may be used in combination.

  The organic pigment is not particularly limited, but azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, Examples thereof include carbon black.

  Examples of the inorganic pigment include, but are not limited to, iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

  Examples of the pigment that can be used in the black ink include carbon black.

  Although it does not specifically limit as a manufacturing method of carbon black, A furnace method, a channel method, etc. are mentioned.

  The average primary particle size of carbon black is usually 15 to 40 nm.

The specific surface area of carbon black by the BET method is usually 50 to 300 m ² / g.

  The DBP oil absorption of carbon black is usually 40 to 150 ml / 100 g.

  The volatile content of carbon black is usually 0.5 to 10% by mass.

  The pH of carbon black is usually 2-9.

  As a commercial product of carbon black, No. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (above, manufactured by Mitsubishi Chemical Corporation), Raven700, 5750, 5250, 5000, 3500, 1255 (above, manufactured by Columbia), Regal400R, 330R, 660R, MoguL, Monarch700, 800, 880, 900, 1000, 1100, 1300 , Monarch 1400 (manufactured by Cabot Corporation), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4A, 4 ( As mentioned above, Degussa) and the like can be mentioned.

  Examples of pigments that can be used for yellow ink include C.I. I. Pigment Yellow 1 (Fast Yellow G), 2, 3, 12 (Disazo Yellow AAA), 13, 14, 16, 17, 20, 23, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55 73, 74, 75, 81, 83 (disazo yellow HR), 86, 93, 95, 97, 98, 100, 101, 104, 108, 109, 110, 114, 117, 120, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185 and the like.

  Examples of pigments that can be used for magenta ink include C.I. I. Pigment Red 1, 2, 3, 5, 7, 9, 12, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 1 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B) (Ca)), 48: 3 (permanent red 2B (Sr)), 48: 4 (permanent red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (brilliant carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 92, 97, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (dimethylquinacridone), 123, 146, 149, 166, 168, 170, 172, 175, 176, 178, 179, 180 184,185,190,192,193,202,209,215,216,217,219,220,223,226,227,228,238,240,254,255,272, and the like.

  Examples of pigments that can be used for cyan ink include C.I. I. Pigment Blue 1, 2, 3, 15 (copper phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 22, 56, 60, 63, 64, Bat Blue 4, Bat Blue 60, and the like.

  Examples of pigments that can be used for red ink, green ink, and blue ink include C.I. I. Pigment red 177, 194, 224, C.I. I. Pigment orange 16, 36, 43, 51, 55, 59, 61, 71, C.I. I. Pigment violet 3, 19, 23, 29, 30, 37, 40, 50, C.I. I. Pigment green 7, 36, and the like.

  The median diameter of the pigment is usually 10 to 150 nm, preferably 20 to 100 nm, and more preferably 30 to 80 nm. When the median diameter of the pigment is 150 nm or less, the saturation of the image can be improved, and the storage stability of the inkjet ink and the ejection stability of the inkjet ink can be improved. On the other hand, when the median diameter of the pigment is 10 nm or more, light resistance can be improved and storage stability can be improved.

  The median diameter of the pigment can be measured using Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.).

  The pigment may be dispersed in water using a dispersant.

  As the dispersant, a water-soluble resin, a water-soluble surfactant, or the like can be used.

  The water-soluble resin is not particularly limited, but styrene, styrene derivatives, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, Examples thereof include block copolymers obtained by polymerizing two or more monomers selected from the group consisting of itaconic acid, itaconic acid derivatives, fumaric acid and fumaric acid derivatives, random copolymers, and salts thereof.

  The water-soluble resin is an alkali-soluble resin that is soluble in an aqueous base solution.

  The weight average molecular weight of the water-soluble resin is usually 3000 to 20000. Thereby, the viscosity of an inkjet ink can be reduced and it can disperse | distribute easily.

  As the water-soluble surfactant, nonionic surfactants, anionic surfactants, and amphoteric surfactants can be used.

  The nonionic surfactant is not particularly limited, but polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, Polyoxyethylene alkyl phenyl ethers such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether, polyoxyethylene-α-naphthyl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene monostyryl phenyl ether, polyoxy Ethylene distyryl phenyl ether, polyoxyethylene alkyl naphthyl ether, polyoxyethylene monostyryl naphthyl ether And polyoxyethylene distyryl naphthyl ether. In addition, a compound having an aromatic ring such as polyoxyethylene polyoxypropylene block copolymer or polyoxyethylene alkylphenyl ether obtained by substituting part of polyoxyethylene of these nonionic surfactants with polyoxypropylene is formalin. A condensate condensed with the above can also be used as a nonionic surfactant.

  The HLB of the nonionic surfactant is usually 12 to 19.5, and preferably 13 to 19. Thereby, the dispersion stability of inkjet ink can be improved.

  The anionic surfactant is not particularly limited, but polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene monostyryl phenyl ether sulfate, polyoxyethylene distyryl phenyl ether sulfate, Polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl phenyl ether phosphate, polyoxyethylene monostyryl phenyl ether phosphate, polyoxyethylene distyryl phenyl ether phosphate, polyoxyethylene alkyl ether carboxylate, Polyoxyethylene alkyl phenyl ether carboxylate, polyoxyethylene monostyryl phenyl ether carboxylate, polyoxyethylene distyryl phenyl ether carbonate Phosphate, naphthalene sulfonate formalin condensate, melanin sulfonate formalin condensate, dialkyl sulfosuccinate ester salt, alkyl sulfosuccinate di salt, polyoxyethylene alkyl sulfosuccinic acid di salt, alkyl sulfoacetate, α-olefin sulfone Examples include acid salts, alkylbenzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfonates, N-acyl amino acid salts, acylated peptides, soaps, and the like.

  Examples of amphoteric surfactants include, but are not limited to, lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethyl Examples thereof include glycine and imidazoline derivatives.

  A resin-coated pigment can also be used as the pigment.

  The resin-coated pigment is imparted with dispersibility because the pigment is coated with a resin having a hydrophilic group and is microencapsulated.

  A method for coating the pigment with a resin having a hydrophilic group to form microcapsules is not particularly limited, and examples thereof include a chemical manufacturing method, a physical manufacturing method, a physicochemical method, and a mechanical manufacturing method. As a specific example of the method of microencapsulation by coating a pigment with a resin having a hydrophilic group, an interfacial polymerization method (two kinds of monomers or two kinds of reactants are separately dissolved in a dispersed phase and a continuous phase). And a method of forming a wall film by reacting both substances at the interface between them; in-situ polymerization method (liquid or gas monomer and catalyst, or two kinds of reactive substances on the continuous phase core particle side) Method of supplying from either side to cause reaction to form wall film); Submerged cured coating method (dropping resin droplets with hydrophilic groups in which pigments are dispersed) To form a wall film); coacervation (phase separation) method (resin solution having a hydrophilic group in which pigment is dispersed is separated into a coacervate (concentrated phase) and a dilute phase having a high polymer concentration To form a wall film); dry in liquid Method (Place the dispersion in a liquid in which the continuous phase of the resin solution with hydrophilic groups in which the pigment is dispersed is not miscible, to make a composite emulsion, and gradually remove the medium in which the wall membrane material is dissolved. Method of forming a wall film); Melt dispersion cooling method (resin which has a hydrophilic group that melts when heated and solidifies at room temperature, melts it, disperses the pigment in it, cools it to fine particles A method of forming a wall film); an air suspension coating method (a pigment is suspended in the air by a fluidized bed and suspended in an air stream, and a solution of a resin having a hydrophilic group is sprayed to form a wall film. Method of forming); Spray drying method (method of spraying the encapsulated stock solution and bringing it into contact with hot air to evaporate and dry the volatile matter to form a wall film); Acid precipitation method (of an anionic group-containing resin) Neutralize at least part of anionic group with base Water solubility and kneading in water together with the pigment, then neutralizing or acidifying with acid, depositing a resin having a hydrophilic group, fixing to the pigment, neutralizing and dispersing)); phase inversion An emulsification method (a method in which a mixture containing a resin having an anionic group and a pigment is used as an organic phase, and water is added to the organic phase, or an organic phase is added to water).

  The resin having a hydrophilic group is not particularly limited, but polyamide, polyurethane, polyester, polyurea, epoxy resin, polycarbonate, melamine resin, phenol resin, polysaccharide, gelatin, gum arabic, dextran, casein, protein, natural rubber, Carboxypolymethylene, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, cellulose, ethyl cellulose, methyl cellulose, nitrocellulose, hydroxyethyl cellulose, cellulose acetate, polyethylene, polystyrene, polymer of (meth) acrylic acid or Copolymer, (meth) acrylic acid ester polymer or copolymer, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) a Acrylic acid copolymer, styrene - maleic acid copolymer, sodium alginate, fatty acids, paraffin, beeswax, water wax, hardened beef tallow, carnauba wax, albumin and the like.

  Although it does not specifically limit as a hydrophilic group, Anionic groups, such as a carboxylic acid group and a sulfonic acid group, are mentioned.

  Examples of the resin having a nonionic group as a hydrophilic group include polyvinyl alcohol, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate or their (co) polymer, and a cationic ring-opening polymer of 2-oxazoline. Etc. Among them, a completely saponified product of polyvinyl alcohol is preferable because it has a low water solubility and is easily dissolved in hot water but is hardly dissolved in cold water.

  The mass ratio of the resin having a hydrophilic group to the pigment is usually 0.1 to 0.9, and preferably 0.2 to 0.7. When the mass ratio of the resin having a hydrophilic group to the pigment is 0.1 or more, the dispersibility of the pigment can be improved, and when it is 0.9 or less, the coloring property of the pigment can be improved. it can.

  The number average molecular weight of the resin having a hydrophilic group is usually 2000 or more from the viewpoint of capsule production.

  As a pigment to be microencapsulated, a self-dispersing organic pigment or a self-dispersing carbon black can also be used. Thereby, even if content of resin which has a hydrophilic group in a capsule is comparatively small, the dispersibility of a pigment can be improved.

  Note that it is preferable to select a resin having a hydrophilic group depending on the method of microencapsulation. For example, polyesters, polyamides, polyurethanes, polyvinyl pyrrolidones, epoxy resins and the like are listed as resins having a hydrophilic group suitable for use in the interfacial polymerization method. As a resin having a hydrophilic group suitable for use in the in-situ polymerization method, a homopolymer or copolymer of (meth) acrylic acid ester, (meth) acrylic acid- (meth) acrylic acid ester copolymer Styrene- (meth) acrylic acid copolymer, polyvinyl chloride, polyvinylidene chloride, polyamide and the like. Examples of the resin having a hydrophilic group suitable for the case of using the liquid curing method include sodium alginate, polyvinyl alcohol, gelatin, albumin, and epoxy resin. Examples of the resin having a hydrophilic group suitable for the coacervation method include gelatin, celluloses, and casein.

  Examples of the resin having a hydrophilic group suitable for the phase inversion method or the acid precipitation method include an anionic resin.

  In the phase inversion method, an anionic resin having self-dispersing ability or solubility in water and a composite or composite of carbon black, or a mixture of carbon black, a curing agent and an anionic resin as an organic phase, In this method, water is introduced into the organic phase, or the organic phase is introduced into water, and self-dispersion (phase inversion emulsification) is performed for microencapsulation. Carbon black includes self-dispersing carbon black. In the phase inversion method, the organic phase may be mixed with a vehicle or additive for inkjet ink. In particular, it is preferable to mix the liquid medium of the ink-jet ink into the organic phase because it is possible to directly produce a dispersion liquid for the ink-jet ink.

  On the other hand, in the acid precipitation method, a part or all of the anionic group of the resin having an anionic group is neutralized with a base, and a step of kneading in water with a pigment such as carbon black, A step of acidifying and precipitating a resin having an anionic group and fixing the resin to the pigment; Furthermore, the acid precipitation method has a step of neutralizing part or all of the anionic groups of the resin having an anionic group contained in the obtained water-containing cake using a base. As a result, a microencapsulated pigment containing a large amount of fine pigment can be produced.

  The organic solvent used for microencapsulation is not particularly limited, but alcohols such as methanol, ethanol, propanol and butanol; aromatic hydrocarbons such as benzol, toluol and xylol; methyl acetate, ethyl acetate, butyl acetate and the like Examples include esters; chlorinated hydrocarbons such as chloroform and ethylene dichloride; ketones such as acetone and methyl isobutyl ketone; ethers such as tetrahydrofuran and dioxane; and cellosolves such as methyl cellosolve and butyl cellosolve.

  Note that the microencapsulated pigment may be once separated from an organic solvent by centrifugation, filtration, or the like, and then dispersed in water to prepare an inkjet ink.

  The average particle size of the encapsulated pigment is usually 50 to 180 nm.

  The water-soluble organic solvent is not particularly limited, but glycerin, ethylene glycol, diethylene glycol, isopropylideneglycerol, 1,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, propylene glycol, dipropylene Glycol, trimethylolpropane, trimethylolethane, ethylene glycol, diethylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol Glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, petriol, etc. Polyhydric alcohols; polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether; ethylene Polyhydric alcohol aryl ethers such as glycol monophenyl ether and ethylene glycol monobenzyl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, Nitrogen-containing heterocyclic compounds such as ε-caprolactam and γ-butyrolactone; formamide, N-methylformamide Amides such as N, N-dimethylformamide, N, N-dimethyl-β-methoxypropionamide, N, N-dimethyl-β-butoxypropionamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, Amines such as triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, thiodiethanol; 3-ethyl-3-hydroxymethyloxetane, propylene carbonate, ethylene carbonate, and the like, polyols having 8 to 11 carbon atoms, and carbon numbers of 8 ˜11 glycol ethers, lower alcohols and the like may be mentioned, and two or more of them may be used in combination.

  Among water-soluble organic solvents, glycerin, ethylene glycol, diethylene glycol, isopropylideneglycerol, 1,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, propylene are preferred in terms of the wettability of inkjet inks. Glycol, dipropylene glycol, trimethylolpropane, trimethylolethane, ethylene glycol, diethylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1, 6-hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol Polyhydric alcohols such as petriol; polyhydric alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether Ethers; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimid Nitrogen-containing heterocyclic compounds such as idazolidinone, ε-caprolactam, γ-butyrolactone; formamide, N-me Amides such as formamide, N, N-dimethylformamide, N, N-dimethyl-β-methoxypropionamide, N, N-dimethyl-β-butoxypropionamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine Amines such as diethylamine and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol; 3-ethyl-3-hydroxymethyloxetane, propylene carbonate, ethylene carbonate and the like are preferable, 1,3-butanediol, diethylene glycol 2,2,4-trimethyl-1,3-pentanediol, triethylene glycol and / or glycerin are more preferred.

  The wettability is a property that retains moisture in the ink-jet ink and prevents the ink-jet ink from drying, and a material having wettability is abbreviated as a wetting agent.

  The content of the wetting agent in the inkjet ink is usually 10 to 60% by mass, and preferably 20 to 50% by mass. When the content of the wetting agent in the inkjet ink is 10% by mass or more, the ejection stability of the inkjet ink can be improved, and when it is 60% by mass or less, the drying property of the inkjet ink is improved. Can do.

  Among water-soluble organic solvents, from the viewpoint of penetrability of inkjet ink, a polyol having 8 to 11 carbon atoms, a glycol ether having 8 to 11 carbon atoms, and a lower alcohol are preferable, and 2-ethyl-1,3-hexanediol is preferable. (Solubility of 4.2% by mass) and 2,2,4-trimethyl-1,3-pentanediol (solubility of 2.0% by mass) are more preferable.

  Examples of the polyol having 8 to 11 carbon atoms include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, and 2,2-diethyl-1,3-propane. Diol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1,2 -Diol etc. are mentioned.

  Examples of the glycol ether having 8 to 11 carbon atoms include diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, and tetraethylene glycol chlorophenyl ether. Can be mentioned.

  Examples of the lower alcohol include ethanol.

  The penetrability is a property that promotes the penetration of the ink-jet ink into the recording medium, and the penetrable is abbreviated as a penetrant.

  The content of the penetrant in the inkjet ink is usually 0.1 to 4% by mass. When the content of the penetrant in the inkjet ink is 0.1% by mass or more, bleeding of the image can be suppressed, and when it is 4% by mass or less, the ejection stability of the inkjet ink can be improved. The image density can be improved.

  The inkjet ink may further contain a wetting agent other than the water-soluble organic solvent.

  The wetting agent other than the water-soluble organic solvent is not particularly limited, and examples thereof include saccharides and derivatives thereof, and two or more kinds may be used in combination.

  The saccharides are not particularly limited, but monosaccharides such as glucose, mannose, fructose, ribose, xylose, arabinose, galactose; disaccharides such as maltose, cellobiose, lactose, sucrose, trehalose; oligosaccharides such as maltotriose; α -Polysaccharides such as cyclodextrin and cellulose.

  Examples of saccharide derivatives include reducing sugars such as sugar alcohols such as D-sorbitol, sorbitan, maltitol, erythritol, lactitol, and xylitol; oxidized sugars of aldonic acid and uronic sugar; amino acids, thioic acids, and the like. Of these, sugar alcohols are preferred.

  The inkjet ink may further contain a water-dispersible resin as necessary. Thereby, an image excellent in film forming property, water repellency, water resistance, weather resistance and image density can be recorded.

  The form in which the water-dispersible resin exists is not particularly limited, and examples thereof include an emulsion.

  The water-dispersible resin is not particularly limited, but is a polyester, polyurethane, polyepoxy resin, polyamide, polyether, poly (meth) acrylic resin, acryl-silicone resin, fluorine-based resin or other condensed synthetic resin, polyolefin resin, Polystyrene resin, polyvinyl alcohol resin, polyvinyl ester resin, polyacrylic acid resin, addition synthetic resin such as unsaturated carboxylic acid resin, natural polymer compounds such as celluloses, rosins, natural rubber, etc. Two or more kinds may be used in combination. Of these, polyurethane, acrylic-silicone resin and fluorine-based resin are preferable.

  The ink-jet ink may further contain an antifoaming agent, a pH adjuster, an antiseptic / antifungal agent, a rust inhibitor, an antioxidant, an ultraviolet absorber, and the like as necessary.

  Although it does not specifically limit as an antifoamer, A silicone type antifoamer, a polyether type | system | group antifoamer, a fatty-acid ester type | system | group antifoamer etc. are mentioned, You may use 2 or more types together. Among these, a silicone-based antifoaming agent is preferable because it has an excellent foam breaking effect.

  The pH adjuster is not particularly limited as long as the pH can be adjusted to 7 or more, but is not limited to amines such as diethanolamine and triethanolamine, and alkali metal such as lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples thereof include hydroxides; carbonates of alkali metals such as lithium carbonate, sodium carbonate and potassium carbonate; ammonium hydroxide and phosphonium hydroxide.

  The antiseptic / antifungal agent is not particularly limited, but 1,2-benzisothiazolin-3-one, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, etc. Is mentioned.

  The rust inhibitor is not particularly limited, and examples thereof include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  The antioxidant is not particularly limited, and examples thereof include phenolic antioxidants (including hindered phenolic antioxidants), amine antioxidants, sulfur antioxidants, phosphorus antioxidants, and the like. .

  The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzone, phenyl salicylate, and paraaminobenzoic acid ester.

  The surface tension at 25 ° C. of the ink-jet ink is usually 20 to 40 mN / m. When the surface tension of the inkjet ink at 25 ° C. is 20 mN / m or more, the occurrence of bleeding can be suppressed, and the ejection stability of the inkjet ink can be improved. On the other hand, when the surface tension of the ink-jet ink at 25 ° C. is 40 mN / m or less, the ink-jet ink easily penetrates into the recording medium and can be dried in a short time.

  The ink jet recording apparatus has means for ejecting the above ink jet ink, and further has control means as necessary.

  The means for ejecting the ink-jet ink is not particularly limited, and examples thereof include an ink-jet head that applies a stimulus (energy) to the ink-jet ink.

  Although it does not specifically limit as irritation | stimulation (energy), A heat | fever (temperature), a pressure, a vibration, light, etc. are mentioned, You may use 2 or more types together. Of these, heat and pressure are preferred.

  For example, when the stimulus is heat, the thermal energy corresponding to the recording signal is applied to the inkjet ink in the inkjet head using a heating resistor to generate bubbles in the inkjet ink. Inkjet ink is discharged from the nozzle.

  In addition, when the stimulus is pressure, by applying a voltage to the piezoelectric element bonded to the pressure chamber in the ink flow path in the ink jet head, the piezoelectric element is bent, and the volume of the pressure chamber is reduced. Inkjet ink is ejected from the nozzles.

  Examples of the control means include a sequencer and a computer.

  Examples of the ink jet recording apparatus include an ink jet printer, a facsimile apparatus, a copying apparatus, and a printer / fax / copier multifunction machine.

  The recording medium on which an image is recorded using an inkjet recording apparatus is not particularly limited, and examples thereof include plain paper, coated paper for printing, glossy paper, special paper, cloth, film, and OHP sheet.

  FIG. 2 shows an ink jet printer as an example of the ink jet recording apparatus.

  The ink jet printer 100 includes a paper feed tray 101 for loading plain paper, a paper discharge tray 102 for stocking plain paper on which an image is recorded, and an ink cartridge loading unit 103. On the upper surface of the ink cartridge loading unit 103, an operation unit 104 on which operation keys, a display, and the like are installed is disposed. The ink cartridge loading unit 103 is provided with an openable and closable cover 103 a for attaching and detaching the ink cartridge 200.

  In the ink jet printer 100, as shown in FIGS. 3 and 4, a carriage 107 is slidably held in the main scanning direction A by a guide rod 105 and a stay 106 that are horizontally mounted on left and right side plates (not shown). It is moved and scanned in the main scanning direction A by a main scanning motor (not shown).

  The carriage 107 includes four inkjet heads 108 that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). And are mounted so that the direction in which the ink droplets are ejected is downward.

  The inkjet head 108 is not particularly limited, but a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like can be used.

  Also, the carriage 107 is equipped with a sub tank 109 for each color for supplying each color ink to the inkjet head 108. The sub tank 109 is supplied with ink-jet ink from an ink cartridge 200 loaded in the ink cartridge loading unit 103 via an ink supply tube (not shown) and is replenished.

  On the other hand, the plain paper P is separated and fed from the plain paper stacking unit 102a one by one as a paper feeding unit for feeding the plain paper P stacked on the plain paper stacking unit (pressure plate) 102a of the paper feed tray 102. A sheet feeding roller 110 to be fed and a separation pad 111 made of a material having a large friction coefficient are disposed to face the sheet feeding roller 110. At this time, the separation pad 111 is biased toward the paper feed roller 110 side.

  A transport belt 113 for electrostatically attracting and transporting the plain paper P as a transport section for transporting the plain paper P fed from the paper feed section via the guide 112 on the lower side of the inkjet head 108; The counter roller 114 for transporting the plain paper P sandwiched between the transport belt 113 and the plain paper P transported substantially vertically upward is changed by approximately 90 ° to follow the transport belt 113. A conveying guide 115 and a tip pressurizing roller 117 urged toward the conveying belt 113 by a pressing member 116 are installed. A charging roller 118 for charging the surface of the conveyor belt 113 is provided.

  The conveyance belt 113 is an endless belt, is stretched between the conveyance roller 119 and the tension roller 120, and can circulate in the direction B in which the plain paper P is conveyed. Further, a guide member 121 is disposed on the back side of the conveyance belt 113 so as to correspond to an image recording area by the inkjet head 108.

  Although it does not specifically limit as the conveyance belt 113, The surface layer which electrostatically adsorbs the plain paper P comprised from resin, such as a tetrafluoroethylene and ethylene copolymer (ETFE) about 40 micrometers thick, and carbon Except for the resistance being controlled, one having a back layer (medium resistance layer, earth layer) made of the same material as the surface layer can be used.

  As a paper discharge unit for discharging the plain paper P on which an image is recorded by the inkjet head 108, a separation claw 122 for separating the plain paper P from the transport belt 113, a discharge roller 123, and a discharge roller. 124 is installed, and a paper discharge tray 103 is disposed below the paper discharge roller 123.

  A double-sided paper feeding unit 125 is detachably attached to the back surface of the inkjet recording apparatus 100. The double-sided paper feeding unit 125 takes in and reverses the plain paper P returned by rotating the transport belt 113 in the reverse direction to the direction B in which the plain paper P is transported. Paper is fed between. A manual paper feed unit 126 is installed on the upper surface of the double-sided paper feed unit 125.

  In the ink jet printer 100, the plain paper P is separated and fed one by one from the paper feed unit, and the plain paper P fed substantially vertically upward is guided by the guide 112, and the conveyance belt 113 and the counter roller 114 are in contact with each other. It is sandwiched and conveyed. Further, the front end is guided by the transport guide 115 and pressed against the transport belt 113 by the front end pressure roller 117, and the transport direction is changed by about 90 °.

  At this time, since the conveying belt 113 is charged by the charging roller 118, the plain paper P is conveyed by being electrostatically attracted to the conveying belt 113. Therefore, by driving the inkjet head 108 according to the image signal while moving the carriage 107, the inkjet ink is ejected onto the stopped plain paper P to record an image for one line. After transporting a predetermined amount, the image for the next line is recorded. Upon receipt of a signal indicating the end of image recording or a signal indicating that the trailing edge of the plain paper P has reached the image recording area, the image recording operation is terminated and the plain paper P is discharged onto the discharge tray 103.

  When the near end of the remaining amount of ink in the sub tank 109 is detected, a required amount of inkjet ink is supplied to the sub tank 109 from an ink cartridge (not shown).

  In the inkjet printer 100, when the inkjet ink in the ink cartridge 200 is used up, the casing of the ink cartridge 200 can be disassembled and the ink bag inside can be replaced. Further, the ink cartridge 200 can supply ink stably even when the ink cartridge 200 is vertically placed and has a front loading configuration. Therefore, even when the upper part of the ink jet printer 100 is closed and installed, for example, when it is stored in a rack or when an object is placed on the upper surface of the ink jet printer 100, The ink cartridge 200 can be easily replaced.

  FIG. 5 shows the ink cartridge 200.

  The ink cartridge 200 is used by mounting an ink bag 201 filled with inkjet ink in a plastic casing 202 detachably attached to the inkjet printer 100.

  The ink bag 201 is composed of a packaging member such as a non-permeable aluminum laminate film or resin film, and after filling and discharging the ink jet ink from the ink injection port 201a, the ink injection port 201a is fused. It is sealed by. Further, the ink bag 201 is formed with an ink discharge port 201b made of a rubber member. When supplying ink jet ink to the sub tank 109, the ink bag 201 is installed at the tip of the ink supply tube at the ink discharge port 201b. Stab the needle.

  The example in which the above-described inkjet ink is applied to a serial type (shuttle type) inkjet recording apparatus in which a carriage scans has been described above, but the present invention can be similarly applied to a line type inkjet recording apparatus having a line type head.

  Examples of the present invention will be described below, but the present invention is not limited to the examples. In addition, a part means a mass part.

(Synthesis of CPVBTMAC)
Into a reaction vessel equipped with a stirrer, a reflux condenser, two dropping funnels, a nitrogen gas inlet tube and a thermometer, 463.5 g of water was charged, and then heated to 80 ° C. Next, under a nitrogen stream, a mixed solution of 500 g (1.89 mol) of an 80 wt% aqueous solution of 4-vinylbenzyltrimethylammonium chloride (VBTMAC) and 20.3 g (0.22 mol) of mercaptoacetic acid and 5 of potassium persulfate A 16.2 g (0.003 mol) weight percent aqueous solution was added dropwise simultaneously over 2 hours. Furthermore, it hold | maintained at 80 degreeC for 3 hours, and obtained the solution of the poly (4-vinyl benzyl trimethyl ammonium chloride) (CPVBTMAC) which has a carboxymethylthio group at the terminal whose solid content is 41.9 mass%. Next, CPVBTMAC was purified by reprecipitation with acetone. CPVBTMAC had a weight average molecular weight of 14,000 and a number average molecular weight of 7,000.

(Synthesis of VBPVBTMAC)
Into a reaction vessel equipped with a stirrer, a reflux condenser and a thermometer, 700.0 g (0.15 mol) of a CPVBTMAC solution having a solid content of 41.9% by mass and 280.0 g of ethanol were charged, and then hydroxylated. 16.7 g (0.20 mol) of a 48% by weight aqueous solution of sodium, 13.0 g (0.04 mol) of tetrabutylammonium bromide and 30.2 g (0.20 mol) of 4- (chloromethyl) styrene were added, The mixture was reacted at 30 ° C. for 72 hours to obtain a solution of poly (4-vinylbenzyltrimethylammonium chloride) (VBPVBTMAC) having a 4-vinylbenzyloxycarbonylmethylthio group at the terminal having a solid content of 32.2% by mass. Next, VBPVBTMAC was purified by reprecipitation with acetone. As a result of measuring ¹ HNMR of VBPVBTMAC, it was found that the introduction rate of terminal 4-vinylbenzyloxycarbonylmethylthio group was almost 100%. VBPVBTMAC had a weight average molecular weight of 14,300 and a number average molecular weight of 7,100.

(Weight average molecular weight and number average molecular weight)
The weight average molecular weight and number average molecular weight of the polymer were measured by the GPC method. At this time, CTO-20A (manufactured by Shimadzu Corporation) is used as the column thermostat, RID-10A (manufactured by Shimadzu Corporation) is used as the detector, and LC-20AD (manufactured by Shimadzu Corporation) is used as the eluent flow path pump. ), DGU-20A (manufactured by Shimadzu Corporation) was used as the degasser, and SIL-20A (manufactured by Shimadzu Corporation) was used as the autosampler. The column includes an aqueous SEC column TSKgel G3000PWXL (Tosoh Corp.) with an exclusion limit molecular weight of 2 × 10 ^5, an aqueous SEC column TSKgel G5000PWXL (Tosoh Corp.) with an exclusion limit molecular weight of 2.5 × 10 ⁶ , and an exclusion limit. An aqueous SEC column TSKgelG6000PWXL (manufactured by Tosoh Corporation) having a molecular weight of 5 × 10 ⁷ was used. Further, the sample was prepared to a concentration of 2 g / 100 mL with an eluent and then used for measurement. Moreover, as an eluent, the aqueous solution which adjusted the density | concentration of acetic acid and sodium acetate to 0.5M each was used. Further, the column temperature was 40 ° C., and the flow rate of the eluent was 1.0 ml / min. In addition, as a standard sample, a calibration curve was obtained using nine types of polyethylene glycols having molecular weights of 1065, 5050, 24000, 50000, 107000, 140000, 250,000, 540000, and 920000, and the weight average molecular weight of the polymer was determined based on the calibration curve. And the number average molecular weight was determined.

(Preparation of dispersion 1 of polymer particles)
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen gas inlet tube and thermometer, 338.1 g (0.43 mol) of a solution of VBPVBTMAC having a solid content of 32.2% by mass, dimethylaminoethyl methacrylate ( (DMAEMA) 67.0 g (0.43 mol), methyl acrylate (MA) 37.0 g (0.43 mol) and water 468.8 g were charged, and the pH was adjusted to 5.0 with hydrochloric acid. The temperature rose. Next, after adding 81.1 g (0.015 mol) of a 5 mass% aqueous solution of potassium persulfate under a nitrogen stream, the mixture was held at 60 ° C. for 6 hours, the solid content was 26.4 mass%, and the median diameter was 800 nm. A dispersion 1 of polymer particles was obtained.

(Preparation of polymer particle dispersion 2)
The amount of the VBPVBTMAC solution having a solid content of 32.2% by mass, DMAEMA, and water added were changed to 684.2 g (0.87 mol), 67.8 g (0.44 mol), and 319.0 g, respectively. In the same manner as in the dispersion 1 of polymer particles, except that 43.0 g (0.43 mol) of ethyl acrylate (EA) was added instead of 0.0 g (0.43 mol), the solid content was 23. A dispersion 2 of polymer particles having 3% by mass and a median diameter of 600 nm was obtained.

(Preparation of polymer particle dispersion 3)
The addition amount of VBPVBTMAC solution having a solid content of 32.2% by mass, DMAEMA and water were changed to 684.2 g (0.87 mol), 406.66 g (2.61 mol) and 319.0 g of water, respectively. The solid content was 24 in the same manner as in the dispersion 1 of polymer particles, except that 334.44 g (2.61 mol) of butyl acrylate (BA) was added instead of 37.0 g (0.43 mol) of MA. A dispersion 3 of polymer particles having a mass ratio of 1 mass% and a median diameter of 650 nm was obtained.

(Synthesis of CPVBTEAC)
Into a reaction vessel equipped with a stirrer, a reflux condenser, two dropping funnels, a nitrogen gas inlet tube and a thermometer, 463.5 g of water was charged, and then heated to 80 ° C. Next, under a nitrogen stream, a mixed solution of 600 g (1.89 mol) of an 80 mass% aqueous solution of 4-vinylbenzyltriethylammonium chloride (VBTEAC) and 20.3 g (0.22 mol) of mercaptoacetic acid and 5 of potassium persulfate A 16.2 g (0.003 mol) mass% aqueous solution was added dropwise simultaneously over 2 hours. Furthermore, it hold | maintained at 80 degreeC for 3 hours, and obtained the solution of the poly (4-vinyl benzyl triethylammonium chloride) (CPVBTEAC) which has a carboxymethylthio group at the terminal whose solid content is 40.8 mass%. Next, CPVBTEAC was purified by reprecipitation with acetone. CPVBTEAC had a weight average molecular weight of 13,000 and a number average molecular weight of 6,000.

(Synthesis of VBCPVBTEAC)
Into a reaction vessel equipped with a stirrer, a reflux condenser and a thermometer, 850.0 g (0.15 mol) of a CPVBTEAC solution having a solid content of 40.8% by mass and 280.0 g of ethanol were charged, and then hydroxylated. 16.7 g (0.20 mol) of a 48% by weight aqueous solution of sodium, 13.0 g (0.04 mol) of tetrabutylammonium bromide and 30.2 g (0.20 mol) of 4-chloromethylstyrene were added at 30 ° C. For 72 hours to obtain a solution of poly (4-vinylbenzyltriethylammonium chloride) (VBPVBTEAC) having a 4-vinylbenzyloxycarbonylmethylthio group at the terminal with a solid content of 30.2% by mass. Next, VBPVBTEAC was purified by reprecipitation with acetone. As a result of measuring ¹ H-NMR of VBPVBTEAC, it was found that the introduction rate of the terminal 4-vinylbenzyloxycarbonylmethylthio group was almost 100%. VBPVBTEAC had a weight average molecular weight of 13,500 and a number average molecular weight of 6,100.

(Preparation of polymer particle dispersion 4)
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen gas inlet tube and a thermometer, 420.3 g (0.43 mol) of a solution of VBPVBTEAC having a solid content of 30.2% by mass, diethylaminoethyl methacrylate (DEAEMA) ) 79.7 g (0.43 mol), 37.0 g (0.43 mol) of methyl acrylate (MA) and 468.8 g of water were added, the pH was adjusted to 5.0 with hydrochloric acid, and the temperature was raised to 60 ° C. Warm up. Next, 81.1 g (0.015 mol) of a 5% by weight aqueous solution of potassium persulfate was added under a nitrogen stream, and then held for 6 hours. The polymer had a solid content of 27.6% by weight and a median diameter of 590 nm. A dispersion 4 of particles was obtained.

(Preparation of polymer particle dispersion 5)
In the synthesis of the pH-responsive polymer fine particle dispersion of Synthesis Example 1, 338.1 g of a terminal vinylbenzyl group-containing VBTMAC polymer solution, 67.0 g (0.43 mol) of DMAEMA (dimethylaminoethyl methacrylate), methyl acrylate 37.0 g (0.43 mol) and 468.8 g of water were added to a solution of VBPVBTMAC having a solid content of 32.2% by mass, DMAEMA, MA and water in amounts of 684.2 g (0.87 mol) and 0 g, respectively. The polymer particles having a solid content of 22.5% by mass and a median diameter of 120 nm were obtained in the same manner as in the dispersion 1 of polymer particles, except that the molecular weight was changed to 56.0 g (0.65 mol) and 319.0 g. Dispersion 5 was obtained.

(Median diameter of polymer particle dispersion)
Using a Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.), the median diameter of the polymer particle dispersion was measured. Specifically, the dispersion of polymer particles was diluted with pure water so that the solid content was 0.2% by mass, and then the pH was adjusted to 5 using hydrochloric acid or sodium hydroxide. Next, after the polymer particle dispersion was diluted with pure water so that the solid content was 0.01% by mass, the median diameter of the polymer particle dispersion was measured.

  Table 1 shows the characteristics of the dispersion of polymer particles.

図６に、高分子粒子の分散液１〜５のｐＨに対するメジアン径の関係を示す。

FIG. 6 shows the relationship of the median diameter to the pH of the polymer particle dispersions 1 to 5.

  From FIG. 6, it can be seen that the dispersions 1 to 4 of the polymer particles have a larger median diameter when the pH is lowered.

  On the other hand, since the dispersion 5 of polymer particles does not have a structural unit derived from a pH-sensitive monomer, the median diameter does not change even when the pH is lowered.

(Preparation of surfactant-dispersed black pigment dispersion)
175 parts of carbon black NIPEX160 (manufactured by Degussa) having a BET specific surface area of 150 m ² / g, an average primary particle size of 20 nm, a pH of 4.0, and a DBP oil absorption of 620 g / 100 g, a dimer of naphthalenesulfonic acid, 3 175 parts of sodium naphthalene sulfonate formalin condensate Pionein A-45-PN (manufactured by Takemoto Yushi Co., Ltd.) and 650 parts of distilled water having a content of a monomer and a tetramer of 50% by mass were premixed. Next, using a disk type media mill DMR type (manufactured by Ashizawa Finetech Co., Ltd.), the filling rate of zirconia beads having a particle size of 50 μm is 55%, the peripheral speed is 10 m / s, and the liquid temperature is 10 ° C. for 3 minutes. Circulated and dispersed. Further, using a centrifuge Model-7700 (manufactured by Kubota Corporation), coarse particles were removed, and a dispersion of a surfactant-dispersed black pigment having a pigment concentration of 13% by mass and a median diameter of 125 nm was obtained. .

(Preparation of surfactant-dispersed cyan pigment dispersion)
A pigment concentration of 13% by mass, median was obtained in the same manner as the dispersion of the surfactant-dispersed black pigment except that a copper phthalocyanine pigment (CI Pigment Cyan 15: 3) was used instead of carbon black. A dispersion of a surfactant-dispersed cyan pigment having a diameter of 93 nm was obtained.

(Production of surfactant-dispersed yellow pigment dispersion)
Pigment Yellow 138 LIONOGEN YELLOW 1010 (manufactured by Toyo Ink Co., Ltd.) was used instead of carbon black in the same manner as the surfactant-dispersed black pigment dispersion, the pigment concentration being 13% by mass, and the median diameter. A dispersion of a surfactant-dispersed yellow pigment having a thickness of 70 nm was obtained.

(Preparation of resin-coated magenta pigment dispersion)
After replacing the inside of the 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel with nitrogen gas, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, polyethylene After charging 4.0 g of glycol methacrylate, 4.0 g of styrene macromer AS-6 (manufactured by Toagosei Co., Ltd.) and 0.4 g of mercaptoethanol, the temperature was raised to 65 ° C. Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate, 36.0 g of styrene macromer AS-6 (manufactured by Toagosei Co., Ltd.), mercapto A mixed solution of 3.6 g of ethanol, 2.4 g of azobisdimethylvaleronitrile, and 18 g of methyl ethyl ketone was dropped into the flask in 2.5 hours. Further, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask in 0.5 hours, and then aged at 65 ° C. for 1 hour. Next, 0.8 g of azobisdimethylvaleronitrile was added, followed by aging for 1 hour. Further, 364 g of methyl ethyl ketone was added to obtain 800 g of a 50% by mass polymer solution. Next, after a part of the polymer solution was dried, the weight average molecular weight of the polymer was measured by GPC method and found to be 15000. At this time, a calibration curve was obtained using polystyrene as a standard sample, and the weight average molecular weight of the polymer was obtained based on the calibration curve. Tetrahydrofuran was used as the eluent.

  28 g of polymer solution, 26 g of C.I. I. Pigment Red 122, 1M aqueous potassium hydroxide solution (13.6 g), methyl ethyl ketone (20 g) and ion-exchanged water (30 g) were stirred and kneaded 20 times using a three-roll mill NR-84A (manufactured by Noritake Company). After the obtained paste was put into 200 g of ion-exchanged water and stirred, methyl ethyl ketone and a part of water were distilled off using an evaporator, and the resin concentration was 13% by mass of pigment and the median diameter was 80 nm. A magenta pigment dispersion was obtained.

(Median diameter of pigment dispersion)
The median diameter of the pigment dispersion was measured using Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.). Specifically, after the pigment dispersion was diluted with pure water so that the solid content was 0.01% by mass, the median diameter of the pigment dispersion was measured.

Example 1
Dispersion KM-9036 (manufactured by Toyo Ink Co., Ltd.), a self-dispersing black pigment dispersion having a pigment concentration of 13% by mass, dispersion 1 of 0.1 part of polymer particles, solid content of 40.0% % Acrylic resin emulsion NANOCRYL-S KPX-02-014 (manufactured by Toyochem), 15 parts of 3-methyl-1,3-butanediol as wetting agent, 15 parts of glycerin as wetting agent, penetrant 2 parts of 2-ethyl-1,3-hexanediol as a surfactant (polyoxyethylene perfluoroalkyl ether) Zonyl FS-300 (manufactured by Dupon) 0.5 parts , 0.05 part of a preservative Proxel GXL (manufactured by Arch Chemicals) having a content of 1,2-benzisothiazolin-3-one of 20% by mass, as a pH adjuster Then, 0.3 part of 2-amino-2-ethyl-1,3-propanediol and 2.55 part of pure water were stirred for 1 hour, and then added using a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm. Pressure filtration was performed to obtain an inkjet ink.

(Example 2)
Surfactant-dispersed black pigment dispersion 61.5 parts with a pigment concentration of 13% by mass, 0.1 part of polymer particle dispersion 1 and urethane resin emulsion Takelac with a solid content of 35.0% by mass 3 parts W5661 (Mitsui Chemicals), 15 parts 1,3-butanediol as a wetting agent, 15 parts triethylene glycol as a wetting agent, 2,2,4-trimethyl-1, as a penetrating agent, 2 parts of 3-pentanediol, 0.5 part of surfactant (perfluoroalkyl polyethylene oxide addition reaction product) Unidyne DSN-403N (manufactured by Daikin Industries), content of 1,2-benzisothiazolin-3-one is 20 Preservative of mass% Proxel GXL (manufactured by Arch Chemicals) 0.05 part, N-cyclohexyl-2-aminoethanesulfonic acid 0 as pH adjuster 0.05 part and 2.8 parts of pure water were stirred for 1 hour, and then filtered under pressure using a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to obtain an inkjet ink.

Example 3
Surfactant-dispersed cyan pigment dispersion having a pigment concentration of 13% by mass, 0.1 part of polymer particle dispersion 1, and urethane resin emulsion Takelac with a solid content of 35.0% by mass 3 parts of W5661 (made by Mitsui Chemicals), 30 parts of glycerin as a wetting agent, 0.5 parts of surfactant KF-643 (made by Shin-Etsu Chemical Co., Ltd.), content of 1,2-benzisothiazolin-3-one 1 part of 20 parts by mass of a preservative Proxel GXL (manufactured by Arch Chemicals Co., Ltd.) 0.05 part, N-cyclohexyl-2-aminoethanesulfonic acid 0.05 part and 20.1 parts pure water as a pH adjuster After stirring for a period of time, pressure filtration was performed using a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to obtain an inkjet ink.

Example 4
46.2 parts of a dispersion of a surfactant-dispersed yellow pigment having a pigment concentration of 13% by weight, a dispersion 1 of 0.1 part of polymer particles, 15 parts of 1,3-butanediol as a wetting agent, Surfactant (polyoxyethylene perfluoroalkyl ether) Zonyl FS having 15 parts of glycerin as a wetting agent, 2 parts of 2-ethyl-1,3-hexanediol as a penetrating agent, and a component content of 40% by mass As a pH adjuster, 0.5 part of -300 (manufactured by Dupon), 0.05 part of a preservative Proxel GXL (manufactured by Arch Chemicals) having a content of 1,2-benzisothiazolin-3-one of 20% by mass After stirring 0.3 parts of 2-amino-2-ethyl-1,3-propanediol and 20.85 parts of pure water for 1 hour, a polyvinylidene fluoride membrane having an average pore size of 5.0 μm was used. Subjected to pressure filtration using a filter to obtain an inkjet ink.

(Example 5)
46.2 parts of a resin-coated magenta pigment dispersion with a pigment concentration of 13% by weight, 0.1 part of polymer particle dispersion 1, 30 parts of 1,3-butanediol as a wetting agent, and a penetrating agent 2 parts of 2-ethyl-1,3-hexanediol, 0.3 part of 2-amino-2-ethyl-1,3-propanediol and 21.4 parts of pure water as a pH adjusting agent for 1 hour After stirring, the mixture was filtered under pressure using a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to obtain an inkjet ink.

(Example 6)
An inkjet ink was obtained in the same manner as in Example 2 except that the polymer particle dispersion 2 was used instead of the polymer particle dispersion 1.

(Example 7)
An inkjet ink was obtained in the same manner as in Example 2 except that the polymer particle dispersion 3 was used instead of the polymer particle dispersion 1.

(Example 8)
An inkjet ink was obtained in the same manner as in Example 2 except that the polymer particle dispersion 4 was used instead of the polymer particle dispersion 1.

Example 9
61.5 parts of a dispersion of a surfactant-dispersed black pigment having a pigment concentration of 13% by weight, a dispersion 1 of 0.03 part of polymer particles, and 3-methyl-1,3-butane as a wetting agent 15 parts of diol, 15 parts of glycerin as a wetting agent, 2 parts of 2-ethyl-1,3-hexanediol as a penetrant, a surfactant having a surfactant component content of 40% by mass (polyoxyethylene Perfluoroalkyl ether) 0.5 part of zonyl FS-300 (manufactured by Dupon), preservative Proxel GXL (manufactured by Arch Chemicals) having a content of 1,2-benzisothiazolin-3-one of 20% by mass After stirring for 0.5 hour, 0.3 part of 2-amino-2-ethyl-1,3-propanediol and 5.62 parts of pure water as a pH adjuster for 1 hour, polyvinylidene having an average pore diameter of 5.0 μm Subjected to pressure filtration using a down fluoride membrane filter to obtain an inkjet ink.

(Example 10)
61.5 parts of a dispersion of a surfactant-dispersed black pigment having a pigment concentration of 13% by mass, a dispersion 1 of 0.05 part of polymer particles, 15 parts of 1,3-butanediol as a wetting agent, 15 parts by weight of glycerin as a wetting agent, 2 parts of 2-ethyl-1,3-hexanediol as a penetrant, and a surfactant (polyoxyethylene perfluoroalkyl ether) with a surfactant component content of 40% by mass ) Zonyl FS-300 (Dupon) 0.5 parts, 1,2-benzisothiazolin-3-one content 20% by weight Preservative Proxel GXL (Arch Chemicals) 0.05 parts, pH After stirring for 1 hour, 0.3 part of 2-amino-2-ethyl-1,3-propanediol and 5.6 parts of pure water as a regulator, polyvinylidene fluoride having an average pore size of 5.0 μm Subjected to pressure filtration using a down Bren filter to obtain an inkjet ink.

(Example 11)
61.5 parts of a surfactant-dispersed black pigment dispersion having a pigment concentration of 13% by mass, 2 parts of a dispersion 1 of polymer particles, 15 parts of 1,3-butanediol as a wetting agent, and a wetting agent 15 parts of glycerin, 2 parts of 2-ethyl-1,3-hexanediol as penetrant, and 40% by mass of surfactant (polyoxyethylene perfluoroalkyl ether) zonyl FS-300 (manufactured by Dupon) 0.5 part, 1,2-benzisothiazolin-3-one content 20% by mass of preservative Proxel GXL (manufactured by Arch Chemicals) 0.05 part, pH adjuster After stirring 0.3 parts of 2-amino-2-ethyl-1,3-propanediol and 3.65 parts of pure water for 1 hour, polyvinylidene fluoride men with an average pore size of 5.0 μm Subjected to pressure filtration using a lens filter to obtain an inkjet ink.

(Example 12)
61.5 parts of a dispersion of a surfactant-dispersed black pigment having a pigment concentration of 13% by mass, a dispersion 1 of 2.5 parts of polymer particles, and 3-methyl-1,3-butane as a wetting agent 15 parts of diol, 15 parts of glycerin as a wetting agent, 2 parts of 2-ethyl-1,3-hexanediol as a penetrant, a surfactant having a surfactant component content of 40% by mass (polyoxyethylene Perfluoroalkyl ether) 0.5 part of zonyl FS-300 (manufactured by Dupon), preservative Proxel GXL (manufactured by Arch Chemicals) having a content of 1,2-benzisothiazolin-3-one of 20% by mass After stirring for 0.5 hour, 0.3 part of 2-amino-2-ethyl-1,3-propanediol and 3.15 parts of pure water as a pH adjuster for 1 hour, polyvinylidene having an average pore size of 5.0 μm Subjected to pressure filtration using a fluoride membrane filter to obtain an inkjet ink.

(Comparative Example 1)
Self-dispersing black pigment dispersion KM-9036 (manufactured by Toyo Ink Co., Ltd.) with a pigment concentration of 13% by mass 61.5 parts, 0.1 part of polymer particle dispersion 5, 3- Surfactant having 15 parts of methyl-1,3-butanediol, 15 parts of glycerin as a wetting agent, 2 parts of 2-ethyl-1,3-hexanediol as a penetrant, and a component content of 40% by mass (Polyoxyethylene perfluoroalkyl ether) Zonyl FS-300 (manufactured by Dupon) 0.5 part, Preservative Proxel GXL (Arch Chemicals Co., Ltd.) having a content of 1,2-benzisothiazolin-3-one of 20% by mass (Manufactured) 0.05 part, 0.3 part of 2-amino-2-ethyl-1,3-propanediol and 5.55 part of pure water as a pH adjusting agent were stirred for 1 hour, and then the average pore size was 5. 0μ Pressurizing and pressure filtration using a polyvinylidene fluoride membrane filter to obtain an inkjet ink.

(Comparative Example 2)
Surfactant-dispersed black pigment dispersion 61.5 parts with a pigment concentration of 13% by mass, 2 parts of polymer particle dispersion 5 and urethane resin emulsion Takelac W5661 with a solid content of 35.0% by mass ( 3 parts by Mitsui Chemicals) 15 parts 1,3-butanediol as a wetting agent, 15 parts triethylene glycol as a wetting agent, 2,2,4-trimethyl-1,3-as a penetrating agent 2 parts of pentanediol, 0.5 part of surfactant (perfluoroalkylpolyethylene oxide addition reaction product) Unidyne DSN-403N (manufactured by Daikin Industries), content of 1,2-benzisothiazolin-3-one is 20% by mass Preservative Proxel GXL (manufactured by Arch Chemicals Co., Ltd.) 0.05 part, N-cyclohexyl-2-aminoethanesulfonic acid 0.0 as a pH adjuster After 5 parts and 0.9 part of pure water were stirred for 1 hour, the mixture was pressure filtered using a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to obtain an inkjet ink.

(Comparative Example 3)
Surfactant-dispersed cyan pigment dispersion 46.2 parts with a pigment concentration of 13% by mass, Polymer particle dispersion 5 with 0.2 parts of a urethane resin emulsion Takelac with a solid content of 35.0% by mass 3 parts of W5661 (made by Mitsui Chemicals), 30 parts of glycerin as a wetting agent, 0.5 parts of surfactant KF-643 (made by Shin-Etsu Chemical Co., Ltd.), content of 1,2-benzisothiazolin-3-one 20 parts by weight of preservative Proxel GXL (manufactured by Arch Chemicals), 0.05 part of N-cyclohexyl-2-aminoethanesulfonic acid and 20 parts of pure water as a pH adjuster were stirred for 1 hour. After that, pressure filtration was performed using a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to obtain an inkjet ink.

(Comparative Example 4)
46.2 parts of a dispersion of a surfactant-dispersed yellow pigment having a pigment concentration of 13% by weight, a dispersion 5 of polymer particles of 0.03 parts, 15 parts of 1,3-butanediol as a wetting agent, Surfactant (polyoxyethylene perfluoroalkyl ether) Zonyl FS having 15 parts of glycerin as a wetting agent, 2 parts of 2-ethyl-1,3-hexanediol as a penetrating agent, and a component content of 40% by mass As a pH adjuster, 0.5 part of -300 (manufactured by Dupon), 0.05 part of a preservative Proxel GXL (manufactured by Arch Chemicals) having a content of 1,2-benzisothiazolin-3-one of 20% by mass After stirring 0.3 parts of 2-amino-2-ethyl-1,3-propanediol and 20.92 parts of pure water for 1 hour, polyvinylidene fluoride membrane having an average pore size of 5.0 μm Subjected to pressure filtration using a filter or to obtain an ink jet ink.

(Comparative Example 5)
46.2 parts of a resin-coated magenta pigment dispersion having a pigment concentration of 13% by weight, 5 parts of a polymer particle dispersion 5 of 0.1 parts, 15 parts of 1,3-butanediol as a wetting agent, and a wetting agent As glycerin 15 parts, surfactant (perfluoroalkyl polyethylene oxide addition reaction product) Unidyne DSN-403N (manufactured by Daikin Industries), content of 1,2-benzisothiazolin-3-one is 20 Preservative of mass% Proxel GXL (manufactured by Arch Chemicals) 0.05 part, 0.3 part of 2-amino-2-ethyl-1,3-propanediol and 22.85 parts of pure water as pH adjuster Was stirred for 1 hour, and then filtered under pressure using a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to obtain an inkjet ink.

(Comparative Example 6)
61.5 parts of a self-dispersing black pigment dispersion KM-9036 (manufactured by Toyo Ink Co., Ltd.) having a pigment concentration of 13% by mass and an acrylic resin emulsion NANOCRYL-S KPX-02-014 having a solid content of 40.0% by mass 3 parts (manufactured by Toyochem), 15 parts 3-methyl-1,3-butanediol as a wetting agent, 15 parts glycerin as a wetting agent, 2-ethyl-1,3-hexanediol as a penetrating agent 2 parts, surfactant (perfluoroalkyl polyethylene oxide addition reaction product) Unidyne DSN-403N (Daikin Kogyo Co., Ltd.) 0.5 part, 1,2-benzisothiazolin-3-one content is 20% by mass Agent Proxel GXL (manufactured by Arch Chemicals) 0.05 parts, 2-amino-2-ethyl-1,3-propane as a pH adjuster After stirring for 1 hour 0.3 parts of pure water 2.65 parts of all, an average pore diameter was pressure filtered using a polyvinylidene fluoride membrane filter 5.0 .mu.m, to obtain an ink jet ink.

(Comparative Example 7)
As a wetting agent, 61.5 parts of a surfactant-dispersed black pigment dispersion having a pigment concentration of 13% by mass, 3 parts of urethane resin emulsion Takelac W5661 (manufactured by Mitsui Chemicals) having a solid content of 35.0% by mass 15 parts of 1,3-butanediol, 15 parts of glycerin as a wetting agent, 2 parts of 2-ethyl-1,3-hexanediol as a penetrant, a surfactant (perfluoroalkyl polyethylene oxide addition reaction product) ) Unidyne DSN-403N (manufactured by Daikin Industries) 0.5 part, Preservative Proxel GXL (manufactured by Arch Chemicals) 0.05 part content of 1,2-benzisothiazolin-3-one, After stirring for 1 hour, 0.3 parts of 2-amino-2-ethyl-1,3-propanediol and 2.65 parts of pure water as a pH adjuster were used. The ink was subjected to pressure filtration using a 5.0 μm polyvinylidene fluoride membrane filter to obtain an inkjet ink.

  Next, the storage stability, image density, ejection stability, and ejection recovery performance of the ink jet inks of Examples and Comparative Examples were evaluated.

<Storage stability>
First, the viscosity at 25 ° C. of the ink-jet ink was measured at 50 revolutions or 100 revolutions using a viscometer RE80L (manufactured by Toki Sangyo Co., Ltd.). Next, the inkjet ink was put in a polyethylene container, sealed, and stored at 70 ° C. for 1 week, and then the viscosity was measured under the same conditions to evaluate the storage stability. In addition, the case where the change rate of the viscosity after storage with respect to the initial viscosity was less than 5% was judged as ◯, the case where it was 5% or more and less than 50% was judged as Δ, and the case where it was 50% or more was judged as x. .

<Image density>
Using an inkjet printer IPSiO GX3000 (manufactured by Ricoh) under an MM environment (25 ± 0.5 ° C, 50 ± 5% RH), the drive voltage of the piezo element is varied so that the ejection amount of the inkjet ink is uniform. The image density was evaluated by setting so that the same amount of inkjet ink was adhered. Specifically, a chart created using Microsoft Word 2003 and containing a black 64-point character “■” is a basis weight of 69.6 g / m ² , a size of 23.2 seconds, and an air permeability of After printing on high-quality paper Mypaper (manufactured by Ricoh Co., Ltd.) for 21.0 seconds, the “■” portion was measured using X-Rite 938, and the image density was evaluated. At this time, the printing mode was set to “plain paper—standard fast” with a driver attached to the ink jet printer.

  In the case of black ink, ◎ when the image density is 1.30 or more, ◯ when it is 1.20 or more and less than 1.30, Δ when it is 1.10 or more and less than 1.20, or less than 1.10. The case was determined as x.

  In the case of yellow ink, ◎ when the image density is 0.85 or more, ◯ when it is 0.80 or more and less than 0.85, △ when it is 0.75 or more and less than 0.80, less than 0.75 The case was determined as x.

  In the case of magenta ink, ◎ when the image density is 1.00 or more, ◯ when it is 0.90 or more and less than 1.00, △ when it is 0.80 or more and less than 0.90, less than 0.80 The case was determined as x.

  In the case of cyan ink, ◎ when the image density is 1.10 or more, ◯ when it is 1.00 or more and less than 1.10, Δ when it is 0.90 or more and less than 1.00, or less than 0.90. The case was determined as x.

<Discharge stability>
Using an inkjet printer IPSiO GX3000 (manufactured by Ricoh) under an MM environment (25 ± 0.5 ° C, 50 ± 5% RH), the drive voltage of the piezo element is varied so that the ejection amount of the inkjet ink is uniform. The ejection stability was evaluated by setting so that the same amount of inkjet ink was adhered. Specifically, a chart including a solid and line pattern having the same area and shape is a high-quality paper sheet having a basis weight of 69.6 g / m ² , a sizing degree of 23.2 seconds, and an air permeability of 21.0 seconds. 100 sheets were continuously printed on paper (manufactured by Ricoh). During printing, when missing dots or flying curves of inkjet ink were found on the chart, the printer nozzle was cleaned as an operation for returning to normal printing, and the ejection stability was evaluated from the total number of times. In addition, the case where the total number of cleanings was 1 or less was judged as ◎, the case where it was 2 or more and less than 5 times, and the case where it was 5 or more times as x.

<Discharge recovery>
Using an inkjet printer IPSiO GX3000 (manufactured by Ricoh) under an HL environment (32 ± 0.5 ° C., 15 ± 5% RH), the drive voltage of the piezo element is varied so that the ejection amount of the inkjet ink becomes uniform. The ejection recoverability was evaluated by setting so that the same amount of inkjet ink was adhered. Specifically, after leaving it in an HL environment (32 ± 0.5 ° C., 15 ± 5% RH) for 3 hours, a nozzle check pattern is printed, and it is confirmed that there are no ejection defects such as missing dots or flying bends. It was left for another 6 days. Next, one sheet of nozzle check pattern with a solid print section on fine paper Mypaper (Ricoh Co., Ltd.) having a basis weight of 69.6 g / m ² , a sizing degree of 23.2 seconds, and an air permeability of 21.0 seconds Printed out and checked for missing dots and flying bends. When there were missing ink dots or flying bends in the nozzle check pattern, the printer nozzle was cleaned as an operation to return to normal printing, and the ejection recovery performance was evaluated from the total number of times. Note that the case where the total number of cleanings was 0 or 1 was judged as ◎, the case where it was 2 times or more and less than 5 times, and the case where it was 5 times or more as x.

表２から、実施例１〜１２のインクジェットインクは、保存安定性、画像濃度、吐出安定性及び吐出回復性に優れることがわかる。

From Table 2, it can be seen that the inkjet inks of Examples 1 to 12 are excellent in storage stability, image density, ejection stability and ejection recovery property.

  On the other hand, in Comparative Examples 1 to 5, since a dispersion of polymer particles not having a structural unit derived from the compound represented by the general formula (2) is used, the image density is lowered.

  Comparative Examples 6 and 7 are derived from the compound represented by the general formula (1), the structural unit derived from the compound represented by the general formula (2), and the compound represented by the general formula (3). Since the dispersion liquid of polymer particles having the structural unit is not used, the image density is lowered.

100 Inkjet printer 108 Inkjet head 200 Ink cartridge

JP-A-5-148442

Claims (5)

Including water, water-soluble organic solvent, pigment and polymer particles,
The polymer particles have the general formula

(In the formula, R ¹ is an alkyl group having 1 to 4 carbon atoms.)
A structural unit derived from a compound represented by the formula:

(In the formula, R ² is an alkyl group having 1 or 2 carbon atoms.)
A structural unit derived from a compound represented by the formula:

(In the formula, R ³ is an alkyl group having 1 or 2 carbon atoms, and k is the degree of polymerization.)
In looking containing a copolymer having structural units derived from compounds represented by,
The compound represented by the general formula (3) has a number average molecular weight of 500 to 50,000 .   An ink container having an ink container in which the inkjet ink according to claim 1 is stored. An inkjet recording apparatus that records information or an image on a recording medium,
An inkjet recording apparatus comprising an inkjet head that ejects the inkjet ink according to claim 1.   A method for producing a recorded matter comprising a step of ejecting the ink jet ink according to claim 1 from an ink jet head to record information or an image on a recording medium.   A recorded matter in which information or an image is recorded on a recording medium by the ink-jet ink according to claim 1.

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