JP2005048188A - Ink for inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink having improved dispersion stability used for inkjet printers. <P>SOLUTION: The ink comprises a pigment and an organic solvent having the solubility parameter of 0.78 or less, wherein silicon-base graft polymer particles with the size of 0.01-0.3 μm are adsorbed on at least one part of the outer surface of the above pigment and dispersed in the organic solvent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink for an ink jet printer in which a pigment is dispersed in an organic solvent. More specifically, the present invention relates to an ink for an ink jet printer having improved pigment dispersion stability.

  Conventionally, in the ink field for inkjet printers in which a pigment is dispersed in an organic solvent, the pigment is dispersed using a dispersant, and various improvements in printing characteristics and storage stability have been made. For example, Patent Document 1 and Patent Document 2 describe inks containing a pigment, a resin, and a dispersant in a silicone-based organic solvent, and show that excellent print quality is obtained by exhibiting quick drying.

  Also, in Patent Document 3, an inkjet ink in which colored resin particles are dispersed in a nonpolar insulating organic solvent is excellent in print drying without bleeding on a recording paper, and is not clogged with a nozzle and is scratch resistant. It is described as excellent.

  However, when the above-mentioned silicone organic solvent is used, there is no suitable dispersant for finely dispersing the pigment, and the dispersed particle diameter of the pigment is as large as 0.5 to 5 μm. Quality will deteriorate. Similarly, when colored resin particles are used, since the colored resin particles are pulverized and dispersed, the dispersed particle size largely sinks, resulting in a decrease in print quality. Moreover, since the organic solvent also uses a hydrocarbon solvent, there is anxiety about safety to the human body.

  Furthermore, the pigment-type water-based inkjet ink that is generally sold is not satisfactory in water resistance.

Japanese Patent Laid-Open No. 04-161467 Japanese Patent Laid-Open No. 04-248879 Japanese Patent Laid-Open No. 05-25417

  Accordingly, an object of the present invention is to stably disperse pigments in an organic solvent in the form of fine particles, have no sedimentation even after long-term storage, have excellent printing stability, and have excellent water resistance and light resistance. An object of the present invention is to provide an ink for an ink jet printer, in which a pigment is dispersed in a solvent and which is excellent in terms of safety to the human body.

  In the ink for an ink jet printer containing a pigment and an organic solvent, the object is to add the silicone-based graft polymer and adsorb the silicone-based graft polymer on at least a part of the outer surface of the pigment. This is solved by dispersing the particles in the form of particles having a particle size in the range of 0.01 μm to 0.3 μm.

  According to the researches of the present inventors, by dispersing the silicone-based graft polymer on the surface of the pigment in an organic solvent in the form of particles having a particle size of 0.01 μm to 0.3 μm, It has been found that the steric repulsion can be increased to prevent the precipitation of the pigment, the dispersion stability can be improved and the printing stability can be improved, and the printing quality can be improved by using a pigment and an organic solvent. Furthermore, it was discovered that the safety of the ink can be improved by using a highly safe silicone-based organic solvent.

  As described above, the oil-based ink jet printer ink of the present invention has improved dispersion stability, such as pigment sedimentation and storage stability, and improved printing stability. In addition, the use of pigments and organic solvents can improve the printing quality such as water resistance and light resistance, and the safety of ink can be improved by using high-boiling silicone organic solvents with high safety. did it.

  The ink for an ink jet printer of the present invention basically contains a pigment, an organic solvent and a silicone-based graft polymer as essential components.

  If the silicone-based graft polymer is a graft polymer having silicone and is adsorbed on the surface of the pigment, the pigment is dispersed in an organic solvent in the form of particles of 0.01 μm to 0.3 μm. Although not particularly limited, those which are self-dispersed with a particle size of 0.01 μm to 0.3 μm, preferably 0.015 to 0.2 μm are more preferable. A more preferable particle size is 0.015 μm to 0.1 μm.

  As used herein, the term “self-dispersing” means that the polymer is not dissolved in an organic solvent and is dispersed only in the graft polymer without using a protective colloid or surfactant that protects the special dispersion. Means. For example, after dissolving the graft polymer in an organic solvent that dissolves the graft polymer, and mixing this solution with an organic solvent that does not dissolve the graft polymer, there is a phenomenon in which the graft polymer does not form a large lump but is dispersed in a granular form. The particle size of the graft polymer can be measured by a general known particle size distribution measuring device, for example, a laser type or light scattering type particle size distribution meter, a centrifugal sedimentation type particle size distribution meter, or the like.

  The particle diameter of the pigment to which the silicone-based graft polymer is adsorbed in the ink for an ink jet printer of the present invention is preferably 0.01 to 0.3 μm, more preferably 0.01 to 0.2 μm in consideration of a decrease in print quality. More preferred. Further preferable ranges are 0.01 to 0.1 μm, 0.05 to 0.25 μm, 0.1 to 0.3 μm, or 0.08 to 0.16 μm.

  The particle size distribution of the primary particle diameter of the pigment in the ink of the present invention is preferably in the range of 0.01 μm to 0.29 μm, and more preferably in the range of 0.01 μm to 0.2 μm from the point of precipitation of the pigment. The particle size distribution of the pigment is, for example, a method in which the crude pigment is dry-ground with a ball mill or the like together with a grinding medium such as a ball, a method in which the crude pigment is ground in a kneader with ethylene glycol and a salt, 0.01 μm by a method of wet pulverization with a pulverization medium, a method of precipitation after dissolving a crude pigment in a specific solvent (for example, a method of precipitation by dissolving water in sulfuric acid and then adding water or adding it in water), etc. It can be controlled within a range of ˜0.29 μm.

  The pigment adsorbed by the silicone-based graft polymer in the ink of the present invention preferably has a charge from the viewpoint of dispersion stability. For example, as the charge of the pigment, the absolute value of the ζ potential is preferably 10 to 300 mV, and more preferably 15 to 200 mV.

  Examples of the pigment that can be used in the ink for an ink jet printer of the present invention include inorganic pigments, organic pigments, and dyes that do not dissolve in a solvent. These pigments can be used alone or in combination of two or more.

  Examples of inorganic pigments include carbon black, titanium oxide, zinc white, zinc oxide, tripone, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, cadmium red, Bengala, molybdenum red, chrome vermilion, molybdate orange, yellow lead, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, pyridian, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, ultramarine blue , Bitumen, cobalt blue, cerulean blue, manganese violet, cobalt violet, mica and the like. Carbon black is particularly preferred.

  Examples of organic pigments include C.I. I. Quinacridone pigments such as CI Pigment Red 122, Red 202, Red 207, Red 209, and Violet 19; I. Quinacridone quinone pigments such as CI Pigment Orange 48 and Orange 49; I. Dioxazine pigments such as CI Pigment Violet 23 and Violet 37; I. Pigment Blue 15, Blue 15: 1, Blue 15: 2, Blue 15: 3, Blue 15: 4, Blue 15: 6, Blue 16, Blue 68, Green 7, Green 36, etc. Phthalocyanine pigments; I. Anthrapyrimidine pigments such as C.I. Pigment Yellow 108; I. Ansanthrone pigments such as CI Pigment Orange 77 and Red 168; I. Indanthrone pigments such as CI Pigment Blue 60; I. Flavanthrone pigments such as C.I. Pigment Yellow 24; I. Anthraquinone pigments such as CI Pigment Yellow 196 and Red 177; I. Perylene pigments such as CI Pigment Red 123, Red 149, Red 178, Red 179, Red 190, and Red 224; I. Perinone pigments such as CI Pigment Yellow 196 and Orange 43; I. Quinophthalone pigments such as CI Pigment Yellow 138; I. Diketopyrrolopyrrole pigments such as CI Pigment Orange 71, Orange 73, Red 254, Red 255, Red 264, and Red 272; I. Thioindigo pigments such as CI Pigment Red 88, Red 181 and Brown 27; I. CI indoline pigments such as CI Pigment Yellow 139, Yellow 185, Orange 69, and Red 260; I. CI indolinone pigments such as CI Pigment Yellow 109, Yellow 110 and Yellow 173; I. Azomethine pigments such as CI Pigment Yellow 101, Yellow 129, Orange 65; I. Benzimidazolone pigments such as CI Pigment Yellow 151, Yellow 154, Yellow 175, Yellow 180, Yellow 181, Yellow 181, Orange 36, Red 175, Red 176, and Red 185; I. Pigment yellow 1, yellow 65, yellow 73, yellow 74, yellow 116, red 3, red 48: 1, red 48: 2, red 48: 3, red 53: 1, red C. 57: 1, monoazo pigments such as Red 115; I. Disazo pigments such as CI Pigment Yellow 12, Yellow 13, Yellow 17, Yellow 81, Yellow 81, Yellow 83, Orange 16; I. Examples thereof include condensed azo pigments such as CI Pigment Yellow 93, Yellow 95, Yellow 128, Red 144, Red 144, Red 166, Red 220, and Red 221. The pigment may be a powdery, granular, or massive dry pigment, or a wet cake or slurry.

  As the dye that does not dissolve in the solvent, azo, anthraquinone, indigo, phthalocyanine, carbonyl, quinoneimine, methine, quinoline, and nitro are preferred, and among these, disperse dyes are particularly preferred.

  In the inkjet printer ink of the present invention, it is particularly preferable to use an organic pigment and / or carbon black as the pigment.

  In the inkjet printer ink of the present invention, the amount of the silicone-based graft polymer relative to the pigment (for example, organic pigment and / or carbon black) is within the range of 5 to 3000 parts by weight of the silicone-based graft polymer with respect to 100 parts by weight of the pigment. It is preferable that Furthermore, it is more preferable that the amount of the silicone graft polymer adsorbed on the pigment is in the range of 20 to 1000 parts by weight of the silicone graft polymer with respect to 100 parts by weight of the pigment. If the amount of the silicone-based graft polymer is 5 parts by weight or more, the dispersion stability is good, and if it is 3000 parts by weight or less, the content of the pigment in the dispersion composition does not decrease. Sufficient pigment concentration can be obtained. In the ink for an ink jet printer of the present invention, a more preferable range of the amount of the silicone-based graft polymer relative to the pigment is in the range of 30 to 1000 parts by weight with respect to 100 parts by weight of the pigment.

  The exact mechanism of silicone-based graft polymer adsorption to pigments (eg, organic pigments and / or carbon black) is not clear, but chemical bonds (eg, basic sites on the pigment surface due to electron and silicone-based graft polymers) Acid-base bonds such as tertiary amino groups introduced into the pigment surface and carboxyl groups introduced into the silicone-based graft polymer, formation of divalent or higher-valent metal ions and silicone-based graft polymers Ionic bond by salt, covalent bond that polymerizes based on active group of pigment surface), physical adsorption (for example, adsorption by cohesive force in which silicone graft polymer becomes insoluble in solvent and aggregates, pigment and silicone graft polymer Such as mechanical adsorption dispersed by a disperser) or physicochemical adsorption (e.g. The corn graft polymer and the pigment are dispersed, and the active group on the pigment surface is reacted with the silicone graft polymer while adsorbing the silicone graft polymer on the pigment surface), or these are appropriately combined. It is considered that the silicone-based graft polymer is adsorbed on the pigment surface.

  The method for measuring the amount of the silicone-based graft polymer adsorbed on the pigment is determined by a known and generally used method. For example, after adjusting the non-volatile content concentration in the ink to 5%, the ink is centrifuged until the supernatant becomes transparent, and the concentration can be measured indirectly by measuring the silicone graft polymer concentration in the supernatant.

As an organic solvent that can be used in the ink for an ink jet printer of the present invention, an organic solvent having a small polarity and an electric resistivity of 10 ⁹ Ω · cm or more is preferable. The upper limit of electrical resistivity is generally about 10 ¹⁸ Ω · cm. Suitable organic solvents for such purposes include, for example, aliphatic hydrocarbon solvents such as hexane and mineral spirits; silicone organic solvents such as dialkylpolysiloxanes and cyclic polydialkylsiloxanes; olive oil, safflower oil, sunflower Vegetable oils such as oil, soybean oil and linseed oil; aromatic hydrocarbon solvents such as benzene, toluene and xylene; ester solvents such as butyl acetate; alcohol solvents such as methanol and butanol; methyl ethyl ketone and isobutyl Examples thereof include ketone solvents such as methyl ketone; aprotic polar solvents such as dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and pyridine. These solvents can be used alone or in admixture of two or more. Among these solvents, considering the influence on the human body, silicone-based organic solvents are preferable, and methylpolysiloxane and cyclic methylpolysiloxane are more preferable. In view of safety such as ignition, a silicone-based organic solvent having a boiling point of 200 ° C. or higher is preferable.

  The ratio of the organic solvent in the ink for an ink jet printer of the present invention is preferably in the range of 50 to 10,000 parts by weight, more preferably in the range of 100 to 3000 parts by weight with respect to 100 parts by weight of the pigment. When the organic solvent is less than 50 parts by weight with respect to 100 parts by weight of the pigment, it is not preferable because the viscosity becomes too high and printing becomes impossible. On the other hand, when the organic solvent is more than 10,000 parts by weight with respect to 100 parts by weight of the pigment, it is not preferable because problems such as the color of the printed matter becoming too light occur.

  The silicone-based graft polymer preferably has a polar group for finely dispersing the pigment and improving the dispersion stability of the pigment. The polar group suitable for such purpose is not particularly limited, and examples thereof include a basic group, an acidic group, a hydroxyl group, etc. In particular, when the pigment is finely dispersed, and when the crosslinking reaction is performed, Hydroxyl groups are preferred. The basic group is not particularly limited, and examples thereof include primary, secondary, tertiary, and quaternary amino groups. Examples of the acidic group include, but are not limited to, a carboxyl group, a sulfonic acid group, a phosphonic acid group, and the like, but the acid strength is particularly weak because the dispersion composition hardly causes aggregation and the reaction rate of the crosslinking reaction. A carboxyl group is more preferable.

  The acid value of the silicone-based graft polymer is preferably in the range of 5 to 100 KOHmg / g. When the acid value is 5 KOHmg / g or more, the affinity with the pigment is increased, whereby a fine ink for an ink jet printer can be obtained, and the dispersion stability is improved. Moreover, if 100 KOHmg / g is made below, it will suppress that the acid strength of a silicone type graft polymer becomes strong, will make self-dispersion easy to occur, will prevent gelatinization at the time of a synthesis | combination, and will make it easy to synthesize | combine.

  The hydroxyl value of the silicone-based graft polymer is preferably in the range of 5 to 100 KOHmg / g. When the hydroxyl value is 5 KOHmg / g or more, the affinity with the pigment is increased, a fine ink for an ink jet printer can be obtained, and the dispersion stability is improved. Moreover, if it is set to 100 KOHmg / g or less, it will suppress that the acid strength of a silicone type graft polymer becomes strong, will make self-dispersion easy to occur, will prevent the gelatinization at the time of a synthesis | combination, and will make it easy to synthesize | combine.

  The amine value of the silicone-based graft polymer is preferably in the range of 5 to 100 KOHmg / g. When the amine value is 5 KOHmg / g or more, the affinity with the pigment is increased, and a fine ink for an ink jet printer can be obtained, whereby the dispersion stability is improved. Moreover, if it is set to 100 KOHmg / g or less, it will suppress that the acid strength of a silicone type graft polymer becomes strong, will make self-dispersion easy to occur, will prevent gelatinization at the time of a synthesis | combination, and will make it easy to synthesize | combine.

  The number average molecular weight of the silicone-based graft polymer is preferably in the range of 2000 to 50000. If the number average molecular weight is 2000 or more, the pigment can be finely dispersed and the precipitation of the pigment can be prevented. Further, if the molecular weight is 50000 or less, it can be easily dissolved in a solvent, and the viscosity of the ink for an ink jet printer can be suppressed from becoming too high. A more preferable range is 3000 to 30000.

  Examples of the silicone graft polymer include acrylic, polyester, polyurethane, epoxy, and amino polymer compounds. These polymer compounds can be used alone or in combination of two or more. Among these types, acrylic polymer compounds are more preferable because of ease of synthesis and grafting and ease of introduction of polar groups.

  In view of ease of self-dispersion in an organic solvent, a grafted acrylic polymer compound is particularly preferred. This facilitates self-dispersion by branching the part adsorbing to the pigment and the part having affinity for the organic solvent on the branch. That is, since the terminal ends of the graft trunks are not solvated, self-dispersion is facilitated. An amphoteric polymer compound having both an acidic group and a basic group is also preferred.

  The grafted acrylic polymer compound preferably has a graft part molecular weight in the range of 500 to 10,000, more preferably 1000 to 8,000.

  As the graft part, silicone is preferable because of its good affinity for the solvent.

  Examples of the method for producing a silicone-based graft polymer include those obtained by reacting a monomer having a polar group, a macromonomer, and a monomer having silicone in a non-reactive solvent in the presence or absence of a catalyst, Among these, those obtained by polymerizing a monomer having a polar group and a silicone-based macromonomer as essential components are preferable. Also preferred is a method in which an acrylic polymer having a reactive group is synthesized and then reacted with a reactive silicone and grafted. The silicone-based graft polymer is preferably not polymerized even when polymerized, but is preferably dissolved or dispersed in a fine state, and those having a particle size of 0.01 μm to 0.3 μm are particularly preferable.

  Among the polar group-containing acrylic monomers used in the present invention, preferred monomers having an acidic group as a polar group include acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, and itaconic acid. , Monomers having a carboxyl group such as fumaric acid, acroyloxyethyl phthalate, acroyloxy succinate, sulfonic acid groups such as 2-ethyl acrylate, 2-methacrylate 2-ethyl acrylate, butyl acrylamide sulfonate, etc. Monomers having a phosphonic acid group such as 2-methacrylic acid 2-ethyl phosphonate, acrylic acid 2-ethyl phosphonate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, Monomers mentioned with such hydroxyl Le hydroxypropyl, and more preferably monomers having inter alia carboxyl group or a hydroxyl group.

  Monomers having a basic group include monomers having a primary amino group such as acrylic amide, aminoethyl acrylate, aminopropyl acrylate, methacrylic acid amide, aminoethyl methacrylate, aminopropyl methacrylate, acrylic Methylaminoethyl acrylate, methylaminopropyl acrylate, ethylaminoethyl acrylate, ethylaminopropyl acrylate, methylaminoethyl methacrylate, methylaminopropyl methacrylate, ethylaminoethyl methacrylate, ethylaminopropyl methacrylate, etc. Monomers having secondary amino groups, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminopropyl acrylate, dimethyl methacrylate Monomers having tertiary amino groups such as noethyl, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, diethylaminopropyl methacrylate, dimethylaminoethyl methyl chloride salt, dimethylaminoethyl methyl methacrylate salt, acrylic acid Monomers having a quaternary amino group such as dimethylaminoethylbenzyl chloride salt and dimethylaminoethylbenzyl chloride methacrylate are preferred.

  The silicone-based macromonomer that introduces the graft part is a polyether-based polyester that adds a siloxane oxide to a hydroxyalkylene monomethacrylate using a cationic catalyst, and a polyester containing a polybasic acid and a hydroxyl group-containing silicone, and then glycidyl methacrylate and ester. Particularly preferred are esterified ester-based materials and water glass in which the starting material is subjected to methoxylation followed by introduction of methacrylate at the terminal.

  As the silicone-based macromonomer, a macromer in which dimethylsiloxane is bonded to a methacryloyl group directly or via an alkyl group is particularly preferable. For example, X-22-174DX (manufactured by Shin-Etsu Chemical Co., Ltd.), AK-5, AK-30, And AK-32 (manufactured by Toagosei Co., Ltd.).

  Other preferred monomers that can be polymerized include methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylate-n-propyl, acrylate-n-butyl, acrylate-t-butyl, benzyl acrylate, methyl methacrylate. , Ethyl methacrylate, isopropyl methacrylate, methacrylate-n-propyl, methacrylate-n-butyl, isobutyl methacrylate, tert-butyl methacrylate, tridecyl methacrylate, benzyl methacrylate, 2-ethylhexyl acrylate, methacrylic acid 2-ethylhexyl, octyl acrylate, octyl methacrylate, lauryl acrylate, lauryl methacrylate, cetyl acrylate, cetyl methacrylate, stearyl acrylate, stearyl methacrylate, behenyl acrylate, behe (Meth) acrylic acid esters such as methyl methacrylate; styrene monomers such as styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-tert-butylstyrene; benzyl itaconate Itaconic acid esters such as dimethyl maleate, etc .; Fumarate esters such as dimethyl fumarate; Acrylonitrile, methacrylonitrile, vinyl acetate; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, Hydroxyl group-containing monomers such as hydroxypropyl acrylate and hydroxypropyl methacrylate; aminoethyl acrylate, aminopropyl acrylate, methacrylamide, aminoethyl methacrylate, aminopropyl methacrylate And amino group-containing monomers such as dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate; and α-olefins such as ethylene.

  Catalysts include peroxides such as t-butyl peroxybenzoate, di-t-butyl peroxide, cumene perhydroxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide; azobisisobutylnitrile, azobis-2 An azo compound such as 1,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile or the like is preferable.

  Non-reactive solvents include aliphatic hydrocarbon solvents such as hexane and mineral spirits; aromatic hydrocarbon solvents such as benzene, toluene and xylene; ester solvents such as butyl acetate; methanol and butanol Alcohol solvents such as: ketone solvents such as methyl ethyl ketone and isobutyl methyl ketone; aprotic polar solvents such as dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and pyridine are preferable. These solvents may be used in combination.

  The reaction method is preferably a known general method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, redox polymerization, etc. Among them, solution polymerization is more preferable because the reaction method is simple.

  The reaction conditions vary depending on the polymerization initiator and the solvent, but the reaction temperature is 180 ° C. or lower, preferably 30 to 150 ° C., and the reaction time is 30 minutes to 40 hours, preferably 2 hours to 30 hours.

  As described above, the present invention adsorbs a silicone-based graft polymer to a pigment, stabilizes the dispersion of the pigment, and prevents sedimentation. From the viewpoint of dispersion stability in various solvents, the silicone-based graft polymer is used. If the graft polymer is crosslinked and adsorbed on the particulate material, the dispersion stability can be further improved.

  The cross-linking method is preferably an ester bond, an amino bond, a urethane bond, an ether bond or a C—C bond by radical reaction, and an ester bond is particularly preferable from the viewpoint of reaction rate, reaction time, stability during dispersion of particulate matter, and the like. .

  As a method of crosslinking the self-dispersing silicone-based graft polymer, a method using a crosslinking agent and a method of introducing a functional group for crosslinking into the polymer compound to be self-dispersed are preferable.

  As the cross-linking agent, those which react with polar groups in the silicone-based graft polymer are preferable. Amino resins such as melamine resin, benzoguanamine resin and urea resin, tolylene diisocyanate-based prepolymer, polyfunctional aromatic polyisocyanate, diphenylmethane Isocyanate, hexamethylene diisocyanate prepolymer, isocyanate resin such as xylylene isocyanate prepolymer and lysine isocyanate prepolymer, epoxy resin such as bisphenol A and acrylic resin having glycidyl group, Ti, Al, Zr Chelate compounds such as Of these, amino resins and epoxy resins are particularly preferred from the viewpoints of reaction rate and reaction temperature. Since the acrylic polymer compound has only one type of functional group, a crosslinking agent may be required.

  The crosslinking functional group introduced into the silicone-based graft polymer is preferably an amino group, a hydroxyl group, a methoxy group, or a glycidyl group. Among these, a hydroxyl group and a glycidyl group are particularly preferable from the viewpoint of reaction rate and reaction temperature.

  As a method of introducing a functional group for crosslinking, a method of polymerizing or condensing using a monomer having a functional group for crosslinking, a polyhydric alcohol, hydroxyamine, polyamine, or the like at the time of synthesis of a polymer compound having an acidic group, A method of synthesizing a prepolymer of a polymer compound having a group and then introducing a crosslinking functional group by polymerization, condensation or addition reaction is preferred. Needless to say, the polymer compound self-disperses after the introduction of the functional group for crosslinking.

  Monomers having a functional group for crosslinking used in the synthesis of the silicone-based graft polymer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glycerol monomethacrylate, polyethylene glycol mono Hydroxyl-containing monomers such as methacrylate, propylene glycol monomethacrylate, polyethylene glycol monoacrylate, propylene glycol monoacrylate; glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; methoxy group containing methoxypolyethylene glycol acrylate and methoxypolyethylene glycol methacrylate Ami such as monomer, acrylamide, methacrylamide, etc. Is preferably a group containing monomer, among others glycidyl group-containing monomer is caused to react after hydroxyl group, and more preferable because of improving the charge of particulate material.

  In the method of synthesizing a prepolymer of a silicone-based graft polymer and then introducing a functional group for crosslinking by polymerization, condensation or addition reaction, a compound having a functional group for crosslinking for introduction by polymerization, condensation or addition reaction Need only have two or more reactive groups, and polyhydric alcohols, polyamines, hydroxyamines, bisphenol A, and polyisocyanates are preferred.

  In the ink for an ink jet printer of the present invention, in addition to the basic essential components of the pigment, the organic solvent, and the silicone-based graft polymer, a surfactant may be contained as necessary.

  The surfactant is used for improving the surface tension of the ink and the wettability of the pigment, preventing drying at the head, and preventing bleeding on the paper. Examples of the surfactant used in the inkjet printer ink of the present invention include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. Among these, particularly preferred surfactants are anionic surfactants and nonionic surfactants.

  Examples of the anionic surfactant include fatty acid salts such as sodium stearate soap, potassium oleate soap and semi-cured beef tallow fatty acid sodium soap, alkyl sulfates such as sodium lauryl sulfate, triethanolamine lauryl sulfate and sodium higher alcohol sulfate, Alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, alkylnaphthalene sulfonates such as sodium alkylnaphthalenesulfonate, alkylsulfosuccinates such as sodium dialkylsulfosuccinate, alkyldiphenylether disulfonates such as sodium alkyldiphenyletherdisulfonate, Alkyl phosphates such as potassium alkyl phosphate, sodium polyoxyethylene lauryl ether sulfate and polyoxyethylene alkyl sulfate trie Polyoxyethylene alkyl sulfate ester salts such Noruamin, alkyl aryl sulfates such as polyoxyethylene alkyl phenyl ether sodium sulfate, polyoxyethylene alkyl phosphate, naphthalene sulfonic acid formalin condensates preferred.

  Examples of cationic surfactants include alkylamine salts such as coconut amine acetate and stearylamine acetate, quaternary ammonium salts such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride and alkylbenzyldimethylammonium chloride, laurylbetaine and stearylbetaine. Amine oxides such as alkylbetaines such as lauryldimethylamine oxide are preferred.

  Nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether and polyoxyethylene higher alcohol ether, polyoxyethylene octyl Polyoxyethylene alkyl allyl ethers such as phenyl ether and polyoxyethylene nonylphenyl ether, polyoxyethylene derivatives, oxyethylene / oxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate , Polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate Non-ionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitol fatty acid esters such as polyoxyethylene sorbitol tetraoleate, and glycerin fatty acid esters Agents are preferred.

  The viscosity of the ink for an ink jet printer of the present invention is preferably in the range of 1 to 20 mP · s. If it is 1 mP · s or more, ink leakage from the cartridge is prevented, and if it is 20 mP · s or less, the ink flying property is stabilized. Furthermore, when considering high-speed response, 2 to 15 mP · s is more preferable.

  The ink for an inkjet printer of the present invention includes, for example, a dispersion in which a pigment (for example, an organic pigment) is dispersed in an organic solvent in which the silicone-based graft polymer is dissolved using a self-dispersing silicone-based graft polymer; After the silicone-based graft polymer is precipitated and adsorbed on the pigment by mixing with an organic solvent in which the system-based graft polymer does not dissolve, further solvent substitution, addition of various additives, pigment concentration adjustment or filtration are performed as necessary. Etc. can be manufactured.

  More specifically, a dispersion process A in which a pigment (for example, an organic pigment) is dispersed in an organic solvent in which the silicone graft polymer is dissolved using a silicone graft polymer, and the silicone in the dispersion obtained in the dispersion process A Injecting an organic solvent in which the graft polymer does not dissolve or injecting and mixing the dispersion obtained in dispersion step A into an organic solvent in which the silicone graft polymer does not dissolve, precipitates the silicone graft polymer The dispersion composition was prepared by a production method comprising a mixing step B for allowing the pigment to be adsorbed to the pigment, a crosslinking step C for fixing the silicone-based graft polymer by crosslinking, if necessary, and a concentration step D for distilling the solvent if necessary. After the product is manufactured, various additives are added, the pigment concentration is adjusted, or filtration is performed.

  In dispersion step A, after dissolving the silicone-based graft polymer in an organic solvent and adding a pigment, if necessary, using a dispersion medium such as glass beads, steel beads or zirconia beads, a bead mill such as a dyno mill or a DSP-mill, A dispersion is obtained by dispersing with a disperser such as a roll mill, sand mill, attritor, kneader or nanomizer. Furthermore, various additives such as a surfactant, a pigment dispersant, a pigment derivative, and a charge generator may be added as necessary.

  The dispersion conditions for dispersing with a disperser depend on the type of pigment and the type of disperser, but considering the economy and the like, the temperature is in the range of 0 ° C. to 150 ° C. and the dispersion time is preferably as short as possible. If it is the range of time-10 hours / kg, it is preferable at the point of productivity. The dispersed particle size after dispersion is preferably submicron or less in terms of volume average diameter, and more preferably 0.5 microns or less in consideration of sedimentation aggregation.

  The method for measuring the dispersed particle size is not particularly limited, but a known and commonly used method is used, and for example, it is measured by a particle size distribution measuring apparatus of a laser scattering method or a centrifugal sedimentation method. Further, a crosslinking agent for crosslinking the silicone graft polymer is mixed before or after dispersion. In particular, it is preferable to mix after dispersion because there is no influence of reaction or the like at the time of dispersion. The ratio of the cross-linking agent is not particularly limited as long as it can be cross-linked to fix the silicone-based graft polymer to the pigment, but is preferably in the range of 2 to 100 parts by weight with respect to 100 parts by weight of the silicone-based graft polymer. A range of parts by weight is more preferred.

  Next, in the mixing step B, an organic solvent in which the silicone graft polymer does not dissolve is added to the dispersion produced in the dispersion step A, or an organic solvent in which the silicone graft polymer does not dissolve in the dispersion obtained in the dispersion step A. Add slowly to solvent and mix. In this case, the dispersion is uniformly mixed using a simple stirrer such as a three-one motor, a magnetic stirrer, a disper, or a homogenizer at or after the addition. Further, using a mixer such as a line mixer, the organic solvent in which the silicone-based graft polymer is not dissolved and the dispersion produced in the dispersion step A are mixed at once. Further, after the addition, a dispersing machine such as a bead mill or a high-pressure spray mill may be used for the purpose of making the precipitated particles finer.

  The organic solvent in which the silicone graft polymer does not dissolve is not particularly limited as long as the silicone graft polymer does not dissolve, but an organic solvent having a solubility parameter of 7.8 or less is particularly preferable. Examples of the organic solvent having a solubility parameter of 7.8 or less include aliphatic hydrocarbons such as hexane, mineral spirits, Isopar series manufactured by Exxon Chemical Co., etc., and silicone such as dialkylpolysiloxane and cyclic polydialkylsiloxane. And vegetable oils such as olive oil, safflower oil, sunflower oil, soybean oil and linseed oil, and diethyl ether. The ratio of the organic solvent used here is preferably in the range of 0 to 10,000 parts by weight with respect to 100 parts by weight of the silicone-based graft polymer in order to increase the pigment concentration in the produced dispersion composition.

  In the crosslinking step C in which the silicone-based graft polymer is immobilized by crosslinking, the crosslinking method is not particularly limited, and examples thereof include a crosslinking method by heating, ultraviolet rays, electron beams, and the like. In particular, the heating method is preferred because of the reactivity or the ability to react with a simple apparatus. The temperature for crosslinking by heating is not particularly limited as long as the dispersion state of the pigment is not destroyed, but is preferably 200 ° C. or less, more preferably 180 ° C. or less.

  The concentration step D is performed according to the pigment concentration and ink characteristics. Further, the concentration step may be performed before the crosslinking step C. Examples of a method for concentrating the solvent include a general atmospheric pressure or vacuum distillation method. For example, when an inkjet ink is formed using a silicone solvent, the organic solvent that dissolves the silicone graft polymer is concentrated by atmospheric or vacuum distillation using a solvent having a boiling point lower than that of the silicone solvent. On the contrary, when an inkjet ink is prepared using an organic solvent that dissolves the silicone-based graft polymer, a silicone solvent having a boiling point lower than that of the organic solvent that dissolves the silicone-based graft polymer is used and concentrated by distillation under normal pressure or reduced pressure. .

  Further, the ink for an ink jet printer of the present invention is adjusted to a predetermined granular material concentration or binder concentration by adding a binder and / or an organic solvent depending on the use. Examples of the binder include natural proteins, celluloses, polyvinyl alcohol, polyacrylamide, aromatic amide, polyacrylic acid, polyvinyl ether, polyvinyl pyrrolidone, acrylic, polyester, alkyd, urethane, amide resin, melamine resin, ether resin, fluorine. A synthetic polymer such as a resin, a styrene acrylic resin, and a styrene maleic resin, a photosensitive resin, a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, or the like is preferable.

  If necessary, the ink for an inkjet printer of the present invention is a peel inhibitor, a leveling agent, a charge adjusting agent such as a metal soap or lecithin, a wetting agent, an antiseptic, a deodorant, a fragrance, a pigment dispersant, a pigment derivative, etc. Can be further blended.

  The method of adjusting the binder, organic solvent and various additives by adding them to the ink for ink jet printers of the present invention may use a simple stirrer such as a disper, and does not require a conventional disperser. Energy saving and low cost production.

  A printer to which the ink for an ink jet printer of the present invention is applied includes a recording head having a plurality of ink discharge ports and energy conversion means for converting electrical energy into ink discharge energy corresponding to the plurality of discharge ports. It is an inkjet printer provided. For example, it is a thermal method such as a known general piezo method or a bubble jet printer. In particular, since an organic solvent is used, a piezo printer is preferable in consideration of safety.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the following description, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified. Moreover, the reagent 1 grade made from a Wako Purechemical company was used for all the reagents without a cautionary statement.

Synthesis Example 1 (Preparation of silicone graft polymer)
n-butyl methacrylate 16.1 parts lauryl methacrylate 10.0 parts styrene 35.0 parts methacrylic acid 6.9 parts glycidyl methacrylate 12.0 parts X-22-174DX (manufactured by Shin-Etsu Chemical) 20.0 parts perbutyl O (Japan) Peroxyester manufactured by Yushi Co., Ltd.) 8.0 parts These components were mixed to prepare a solution.

  Next, 100 parts of methyl ethyl ketone (reagent grade 1 of Wako Pure Chemical Industries, Ltd.) was weighed into a reaction vessel equipped with a nitrogen introduction tube, and the temperature was raised to 75 ° C. while nitrogen sealing was performed. The said solution was dripped over 4 hours, and it was made to react at 75 degreeC after completion | finish of dripping for 6 hours. The solution after the reaction was a silicone-based graft polymer having a nonvolatile content of 46.1%, an acid value of 44.0 KOH mg / g, and a number average molecular weight of 11800.

  1 part of this polymer compound was diluted with a dimethylsiloxane solvent KF-96L-1.0 (manufactured by Shin-Etsu Chemical Co., Ltd.). When 0.5 part of dimethylsiloxane solvent was added, it was self-dispersed to obtain a dispersion having an average particle size of 0.045 μm (measured with a laser Doppler type particle size distribution analyzer N4 PLUS manufactured by Coulter).

  In addition, 1 part of this polymer compound was diluted with an aliphatic hydrocarbon solvent IsoApar G (manufactured by Exxon Chemical Co., Ltd.). When 1.0 part of Isopar G was added, it was self-dispersed to obtain a dispersion having an average particle size of 0.048 μm (measured with a laser Doppler type particle size distribution meter N4 PLUS manufactured by Coulter).

Synthesis Example 2 (Preparation of silicone graft polymer)
n-Butyl methacrylate 21.0 parts Styrene 25.0 parts 2-Hydroxyethyl methacrylate 15.0 parts Lauryl methacrylate 10.0 parts X-22-174DX (manufactured by Shin-Etsu Chemical) 20.0 parts Glycidyl methacrylate 12.0 parts Butyl O (Peroxy ester manufactured by NOF Corporation) 8.0 parts These components were mixed to prepare a solution.

  Next, 100 parts of methyl ethyl ketone (reagent grade 1 of Wako Pure Chemical Industries, Ltd.) was weighed into a reaction vessel equipped with a nitrogen introduction tube, and the temperature was raised to the boiling point while sealing with nitrogen. The solution was added dropwise over 4 hours, and reacted for 6 hours while refluxing after completion of the addition. The solution after the reaction was a polymer compound having a nonvolatile content of 45.6%, a hydroxyl value of 64.0 KOH mg / g, and a number average molecular weight of 10400.

  1 part of this polymer compound was diluted with a dimethylsiloxane solvent KF-96L-1.0 (manufactured by Shin-Etsu Chemical Co., Ltd.). When 0.5 part of dimethylsiloxane solvent was added, it was self-dispersed to obtain a dispersion having an average particle size of 0.105 μm (measured with a laser Doppler type particle size distribution analyzer N4 PLUS manufactured by Coulter).

Synthesis Example 3 (Preparation of silicone graft polymer)
n-Butyl methacrylate 28.1 parts Lauryl methacrylate 10.0 parts Styrene 35.0 parts Methacrylic acid 6.9 parts X-22-174DX (manufactured by Shin-Etsu Chemical) 20.0 parts Perbutyl O (Nippon Yushi Co., Ltd. Ester) 8.0 parts These ingredients were mixed to prepare a solution.

  Next, 100 parts of methyl ethyl ketone (reagent grade 1 of Wako Pure Chemical Industries, Ltd.) was weighed into a reaction vessel equipped with a nitrogen introduction tube, and the temperature was raised to the boiling point while sealing with nitrogen. The above solution was added dropwise over 2 hours and reacted for 14 hours while refluxing after completion of the addition. The solution after the reaction was a silicone-based graft polymer having a nonvolatile content of 47.0%, an acid value of 44.5 KOH mg / g, and a number average molecular weight of 9900.

  1 part of this polymer compound was diluted with a dimethylsiloxane solvent KF-96L-1.0 (manufactured by Shin-Etsu Chemical Co., Ltd.). When 0.3 part of dimethylsiloxane solvent was added, it was self-dispersed to obtain a dispersion having an average particle size of 0.119 μm (measured with a laser Doppler type particle size distribution analyzer N4 PLUS manufactured by Coulter).

Synthesis Example 4 (Preparation of silicone graft polymer)
n-butyl methacrylate 26.8 parts styrene 30.0 parts 2-hydroxyethyl methacrylate 10.5 parts 4-vinylpyridine 12.7 parts X-22-174DX (manufactured by Shin-Etsu Chemical Co., Ltd.) 20.0 parts perbutyl O (Nippon Yushi) 8.0 parts of Peroxyester manufactured by the company) These components were mixed to prepare a solution.

  Next, 100 parts of methyl ethyl ketone (reagent grade 1 of Wako Pure Chemical Industries, Ltd.) was weighed into a reaction vessel equipped with a nitrogen introduction tube, and the temperature was raised to the boiling point while sealing with nitrogen. The above solution was added dropwise over 2 hours and reacted for 14 hours while refluxing after completion of the addition. The solution after the reaction was a polymer compound having a nonvolatile content of 48.6%, a hydroxyl value of 44.0 KOH mg / g, an amine value of 65.1 KOH mg / g, and a number average molecular weight.

  1 part of this polymer compound was diluted with a dimethylsiloxane solvent KF-96L-1.0 (manufactured by Shin-Etsu Chemical Co., Ltd.). When 0.3 part of dimethylsiloxane solvent was added, it was self-dispersed to obtain a dispersion having an average particle size of 0.09 μm (measured with a laser Doppler type particle size distribution analyzer N4 PLUS manufactured by Coulter).

Synthesis Example 5 (Preparation of polymer)
n-Butyl methacrylate 16.1 parts Lauryl methacrylate 30.0 parts Styrene 35.0 parts Methacrylic acid 6.9 parts Glycidyl methacrylate 12.0 parts Perbutyl O (Peroxy ester manufactured by NOF Corporation) 8.0 parts Were mixed to prepare a solution.

  Next, 100 parts of methyl ethyl ketone (reagent grade 1 of Wako Pure Chemical Industries, Ltd.) was weighed into a reaction vessel equipped with a nitrogen introduction tube, and the temperature was raised to the boiling point while sealing with nitrogen. The solution was added dropwise over 4 hours, and reacted for 6 hours while refluxing after completion of the addition. The solution after the reaction was a polymer compound having a nonvolatile content of 47.3%, an acid value of 44.2 KOH mg / g, and a number average molecular weight of 9800.

  1 part of this polymer compound was diluted with a dimethylsiloxane solvent KF-96L-1.0 (manufactured by Shin-Etsu Chemical Co., Ltd.). When 0.8 part of dimethylsiloxane solvent was added, it became cloudy and aggregated, resulting in a dispersion having an average particle size of 1.25 μm (measured with a laser Doppler type particle size distribution meter N4 PLUS manufactured by Coulter).

  Various characteristics from Synthesis Example 1 to Synthesis Example 5 are shown in Table 1.

Example 1
To the Dino mill KDL type with a 300cc glass container,
Fastengen Blure TGR as the 130.0 parts pigment of the silicone graft polymer of Synthesis Example 1
(Copper phthalocyanine blue pigment manufactured by Dainippon Ink & Chemicals, Inc.) 57.0 parts Solsperse 5000 3.0 parts methyl ethyl ketone 37.0 parts KF-96L-2 37.0 parts 3 mmφ zirconia beads 250 cc as a phthalocyanine pigment derivative
Was cooled with water at 5 ° C. and dispersed at a rotation speed of 1000 rpm for 2 hours to obtain a dispersed slurry. afterwards,
13.2 parts of the above dispersion slurry 30.9 parts of methyl ethyl ketone 30.9 parts of KF-96L-2 were mixed to obtain a mixed solution.

  Next, 75 parts of KF-96L-2 was weighed out as a silicone solvent, put into a 300 cc eggplant flask, and stirred with a magnetic stirrer. While stirring, the mixed solution was slowly dropped to deposit a silicone-based graft polymer on the surface of the particulate material.

  After the dropwise addition, methyl ethyl ketone was desolvated by distillation under reduced pressure and further subjected to a crosslinking reaction at 120 ° C. for 5 hours to obtain a dispersion composition having a pigment concentration of 4.75%. The obtained dispersion composition has a dispersion particle size of 0.125 μm (measured with a laser Doppler type particle size distribution analyzer N4 PLUS manufactured by Coulter, Inc.), and KF-96L-1 is used for this dispersion composition. The concentration of the non-volatile component was adjusted to 5%, and the amount of resin adsorbed by centrifugal sedimentation was measured from the non-volatile component of the supernatant with a centrifugal force of 33500 G for 5 hours. Was adsorbed. Further, transmission electron micrographs before and after adsorption of the organic pigment polymer in the dispersion composition are shown in FIGS. 1 and 2, respectively. As shown in FIG. 2, it can be confirmed that the organic pigment adsorbed with the polymer clearly has a polymer adsorbed on the pigment surface, which is not seen in the case of the organic pigment alone in FIG.

  Further, 10 parts of KF-96-10 and the above dispersion composition to 3 parts in terms of pigment (63.1 parts) are added with KF-96L-2 to make a total amount of 100 parts, and filtered through a filter with a 1 μm aperture. An ink for an oil-based ink jet printer having a pigment concentration of 3% was prepared.

  As shown in Table 3 below, this ink had a small particle size and viscosity, no change after storage test and no sedimentation. In the printing test, the printing stability and re-ejectability were very good.

Comparative Example 1
In a 500cc plastic bottle,
Fastogen Blue TGR as a pigment
(Copper phthalocyanine blue pigment manufactured by Dainippon Ink & Chemicals, Inc.) 3.0 parts MGS-F75 (nonionic surfactant manufactured by Nikko Chemicals) 0.5 parts Tamanol 135 (rosin resin manufactured by Arakawa Chemical) 3.0 parts Technocare FRV (Toshiba Silicone Silicone Oil) 29.5 parts Technocare FRV (Toshiba Silicone Silicone Oil) 5.0 parts KF-96L-2 (Shin-Etsu Chemical Dimethylsiloxane) 37.0 parts Oleyl Alcohol 22.0 300 parts of 3 mmφ zirconia beads were weighed and dispersed for 2 hours with a paint shaker (manufactured by Aisin Co., Ltd.) to prepare an oil-based inkjet ink.

  As shown in Table 3 below, this ink had a particle size and viscosity larger than those of Example 1, a particle size and viscosity after the storage test were increased, sedimentation was observed, and printing stability and redispersibility were inferior.

Example 2
Table 2 below shows the same procedure as in Example 1 except that Cinquasia Magenta RT-355-D (manufactured by Ciba Specialty Chemicals) was used instead of Fastogen Blue TGR pigment and Solsperse 5000 used in Example 1. A dispersion composition was prepared.

  Further, an oil-based ink jet printer ink having a pigment concentration of 3% was prepared in the same manner as in Example 1. As shown in Table 3, this ink had a small particle size and viscosity, no change after storage test and no sedimentation. In the printing test, the printing stability and re-ejectability were very good.

Comparative Example 2
In the same manner as in Example 1, except that 126.8 parts of the polymer of Synthesis Example 5 and 3.2 parts of methyl ethyl ketone were used instead of 130.0 parts of the silicone-based graft polymer of Synthesis Example 1 used in Example 2, Dispersion compositions shown in Table 2 below were prepared.

  Further, an oil-based inkjet printer ink having a pigment concentration of 3% was prepared in the same manner as in Example 2. As shown in Table 3 below, this ink had a larger particle size than that of Example 2, and sedimentation was observed after the storage test. Also in the printing test, ejection failure occurred, and printing stability and re-ejection properties were inferior.

Example 3
A dispersion composition shown in Table 2 below was prepared in the same manner as in Example 1 except that Yellow HG (manufactured by Clariant) was used instead of Fastogen Blue TGR pigment and Solsperse 5000 used in Example 1.

  Further, an oil-based inkjet printer ink having a pigment concentration of 3% was prepared in the same manner as in Example 1. As shown in Table 3 below, this ink had a small particle size and viscosity, no change after storage test and no sedimentation. In the printing test, the printing stability and re-ejectability were very good.

Example 4
Dispersion compositions shown in Table 2 below were prepared in the same manner as in Example 1 except that Printex 85 (Degussa carbon black pigment) was used instead of Fastogen Blue TGR pigment used in Example 1. .

  Further, an oil-based ink jet printer ink having a pigment concentration of 3% was prepared in the same manner as in Example 1. As shown in Table 3 below, this ink had a small particle size and viscosity, no change after storage test and no sedimentation. In the printing test, the printing stability and re-ejectability were very good.

Comparative Example 3
In a 500cc plastic bottle,
Printex 85 as pigment
(Carbon black pigment manufactured by Degussa) 10.0 parts Nonion OP80R (nonionic surfactant manufactured by NOF Corporation) 2.5 parts Tamanol 510 (phenolic resin manufactured by Arakawa Chemical Co., Ltd.) 15.0 parts Isopar L oleyl alcohol 300 parts of 0 part 3 mmφ zirconia beads were weighed and dispersed for 2 hours with a paint shaker (manufactured by Aisin Co., Ltd.) to prepare an oil-based inkjet ink.

  As shown in Table 3 below, this ink had a larger particle size and viscosity than those of the above examples, and sedimentation was observed and printing stability was inferior.

Example 5
Example 1 is the same as Example 1 except that 131.6 parts of the silicone-based graft polymer of Synthesis Example 1 and 37 parts of methyl ethyl ketone used in Example 1 are replaced with 131.6 parts of the polymer of Synthesis Example 2 and 35.4 parts of methyl ethyl ketone. Similarly, dispersion compositions shown in Table 2 below were prepared.

  Further, an oil-based ink jet printer ink having a pigment concentration of 10% was prepared in the same manner as in Example 1. As shown in Table 3 below, this ink had a small particle size and viscosity, no change after storage test and no sedimentation. In the printing test, the printing stability and re-ejectability were very good.

Example 6
In the Dino mill KDL type with a 300cc glass container,
Fastengen Blure TGR as 127.7 parts pigment of silicone graft polymer of Synthesis Example 3
(Copper phthalocyanine blue pigment manufactured by Dainippon Ink & Chemicals, Inc.) 57.0 parts Solsperse 5000 as a phthalocyanine pigment derivative
3.0 parts methyl ethyl ketone 39.3 parts KF-96L-2 37.0 parts 3 mmφ zirconia beads 250 cc
Was cooled with water at 5 ° C. and dispersed at a rotation speed of 1000 rpm for 2 hours to obtain a dispersed slurry. afterwards,
13.2 parts of the above dispersion slurry 30.9 parts of methyl ethyl ketone 30.9 parts of KF-96L-2 were mixed to obtain a mixed solution.

  Next, 75 parts of KF-96L-2 was weighed out as a silicone solvent, put into a 300 cc eggplant flask, and stirred with a magnetic stirrer. While stirring, the mixed solution was slowly dropped to deposit a silicone-based graft polymer on the surface of the particulate material.

  After the dropping, methyl ethyl ketone was desolvated by distillation under reduced pressure to obtain a dispersion composition having a pigment concentration of 4.85%. The obtained dispersion composition has a dispersion particle size of 0.174 μm (measured with a laser Doppler type particle size distribution meter N4 PLUS manufactured by Coulter, Inc.), and KF-96L-1 is used for this dispersion composition. The concentration of the non-volatile component was adjusted to 5%, and the amount of resin adsorbed by centrifugal sedimentation was measured from the non-volatile component of the supernatant over a period of 33 hours with a centrifugal force of 33500G. It had been.

  Furthermore, 10 parts of KF-96-10 and the above dispersion composition were added to an amount of 3 parts in terms of pigment (61.9 parts), and KF-96L-2 was added to make a total of 100 parts, and filtered through a filter having a diameter of 1 μm. An ink for an oil-based ink jet printer having a pigment concentration of 3% was prepared.

  As shown in Table 3 below, this ink had a small particle size and viscosity, no change after storage test and no sedimentation. In the printing test, the printing stability and re-ejectability were very good.

Example 7
Example 12 except that 123.5 parts of the polymer of Synthesis Example 4 and 43.5 parts of methyl ethyl ketone were used in place of 127.7 parts of the silicone graft polymer of Synthesis Example 2 and 39.3 parts of methyl ethyl ketone used in Example 5. In the same manner as in No. 1, dispersion compositions shown in Table 2 below were prepared.

  Further, an oil-based ink jet printer ink having a pigment concentration of 3% was prepared in the same manner as in Example 5. As shown in Table 3 below, this ink had a small particle size and viscosity, no change after storage test and no sedimentation. In the printing test, the printing stability and re-ejectability were very good.

  Here, the pigment concentration was measured by measuring the dispersion composition in an about 2 g aluminum petri dish and drying it in an oven at 220 ° C. for 60 minutes.

  In Table 2 below, the dispersed particle size was measured by a laser Doppler type particle size distribution analyzer N4 PLUS manufactured by Coulter. In addition, the amount of adsorption is adjusted by adjusting the concentration of nonvolatile components to 5% using KF-96L-1 (manufactured by Shin-Etsu Chemical Co., Ltd.), and centrifugal force of 33500G is centrifuged from the nonvolatile components of the supernatant over 5 hours. The amount of resin adsorption on the pigment 100 was measured.

  Next, the characteristics of the oil-based ink jet printer ink were examined. Here, the particle size was measured with a laser Doppler type particle size distribution meter N4 PLUS manufactured by Coulter. The viscosity was measured with an R-type viscometer manufactured by Toki Sangyo Co., Ltd. at a rotation speed of 100 rpm. For those that could not be measured at 100 rpm, the number of revolutions was reduced. In the storage test, 40 g of ink was measured in a 60 cc glass container, sealed, and left in a constant temperature bath at 60 ° C. for 2 weeks. As a result, the case where no sediment was observed was indicated by ◯, and the case where sediment was observed was indicated by ×. The printing test is packed in Epson's C-520 ink cartridge, printed on A4 paper with a C-520 inkjet printer, and continuously printed with the Industri Pattern of the Electronics Industry Association for stable printing over 1000 sheets. Are indicated by ◯, those requiring cleaning but having continuously printed 1000 sheets or more are indicated by △, and those which are clogged and cannot be printed are indicated by ×. As for re-ejectability, the ink was set in a C-520 ink jet printer and allowed to stand at room temperature for 1 month, and then a printing test was performed again. Those showing printing were indicated by Δ, and those not showing stable printing were indicated by ×. The results are shown in Table 3.

2 is an electron micrograph of an organic pigment in a dispersion composition in Example 1 before polymer adsorption. 2 is an electron micrograph after polymer adsorption of an organic pigment in a dispersion composition in Example 1. FIG.

Claims (10)

An ink for an ink jet printer containing a pigment and an organic solvent, wherein the solubility parameter of the organic solvent is 0.78 or less. Ink for an inkjet printer according to claim 1,
Silicone graft polymer is blended,
The silicone-based graft polymer is dispersed in particles having a particle size in the range of 0.01 μm to 0.3 μm in the organic solvent in a state of being adsorbed on at least a part of the outer surface of the pigment. The ink for an ink jet printer according to claim 1. The inkjet according to claim 2, wherein the pigment is selected from the group consisting of an inorganic pigment, an organic pigment, and a dye that does not dissolve in a solvent, and the particle size of the pigment is in the range of 0.01 µm to 0.3 µm. Ink for printers. The ink for an ink jet printer according to claim 2, wherein the silicone-based graft polymer is adsorbed within a range of 5 to 3000 parts by weight with respect to 100 parts by weight of the pigment. The pigment is an organic pigment and / or carbon black;
In the state where the silicone-based graft polymer is adsorbed on at least a part of the outer surface of the organic pigment and / or carbon black, the organic solvent is formed into particles having a particle size in the range of 0.01 μm to 0.3 μm. The ink for an ink jet printer according to claim 2 or 3, wherein the ink is dispersed. The organic solvent is a solvent having a small polarity and an electric resistivity of 10 ⁹ Ω · cm or more, and the organic solvent is blended at a ratio in the range of 50 to 10,000 parts by weight with respect to 100 parts by weight of the pigment. The ink for an ink jet printer according to claim 2, wherein the ink is used. The ink for an inkjet printer according to claim 2 or 6, wherein the organic solvent is a silicone-based organic solvent. The ink for an ink jet printer according to claim 7, wherein the silicone organic solvent comprises a methylpolysiloxane and / or a cyclic methylpolysiloxane structure. The ink for an ink jet printer according to claim 2, wherein the silicone-based graft polymer has a polar group. An ink for an ink jet printer, wherein the polar group is selected from at least a carboxyl group, a hydroxyl group and an amino group.

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