JP2008231340A - Inkjet recording ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording ink which is excellent in storage stability and discharging stability and has a high color-developing property on plain paper and glossy paper and a high glossing property on glossy paper. <P>SOLUTION: This inkjet recording ink is characterized by comprising water, a pigment, a polymer for dispersing the pigment, a pigment derivative represented by formula (1), and a compound represented by formula (2): R-POn-EOm-H (2). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink for ink jet recording which is excellent in storage stability and ejection stability, and has both high colorability on plain paper and glossy paper and high glossiness on glossy paper.

  As inks for ink jet recording, both inks using dyes as pigments and inks using pigments are widely used. In an ink using a pigment, a method using a surfactant as a means for dispersing the pigment in water (see Patent Document 1), a method using a dispersion polymer having a hydrophobic part and a hydrophilic part (see Patent Document 2), Further, a method of coating the surface of the pigment with a polymer has been studied, and examples thereof include those by phase inversion emulsification reaction or acid precipitation (see Patent Document 3).

JP-A-01-301760 Japanese Patent Publication No. 5-064724 Japanese Patent Laid-Open No. 10-140065

  However, in any case, since a polymer containing styrene as a main constituent is used as a method for dispersing the pigment, the fixability is not so much, and yellowing is easily caused by long-term storage of the printed matter. In addition, in order to reduce bleeding on paper, conventional water-based inks require substances having a hydrophilic part and a hydrophobic part such as surfactants and glycol ethers. When these substances are present in the ink, There was a problem that the adsorption / desorption of the polymer from the slag was likely to occur and the storage stability was poor. On the other hand, with inks that do not use these substances, there is a problem in that the permeability to paper is insufficient and the type of paper is limited in order to perform uniform printing, which tends to cause a reduction in the printed image.

  Furthermore, for example, additives (acetylene glycol, acetylene alcohol, silicon surfactant, di (tri-ethylene) for improving print quality are added to a conventional pigment dispersion (referred to as a pigment dispersed by a general dispersant). ) When ethylene glycol monobutyl ether or 1,2-alkylene glycol or a mixture thereof is used, long-term storage stability cannot be obtained, and the re-solubility is poor, so that the ink dries and easily becomes clogged with the nozzles of the inkjet head. There have been problems such as a problem such as attacking a material such as an adhesive used for a substance constituting the head to lower the adhesive strength to deteriorate the ejection stability.

  In addition, the pigment dispersed by such a general dispersant has a high residual viscosity because the residual dispersant remains in the ink, and the dispersant does not contribute sufficiently to the dispersion and is detached from the pigment. There was a problem of ending up. When the viscosity of the ink is increased, the amount of the coloring material such as pigment is limited, and there is a problem that sufficient print quality cannot be obtained particularly on plain paper.

  The ink for inkjet recording of the present invention contains water, a pigment, a polymer for dispersing the pigment, a pigment derivative represented by formula (1), and a compound represented by formula (2). It is characterized by.

式（１）中、Ｘ₁は、−ＮＨ−、−Ｏ−、−ＣＯＮＨ−、−ＳＯ₂ＮＨ−、−ＣＨ₂ＮＨ−、−ＣＨ₂ＮＨＣＯＣＨ₂ＮＨ−または−Ｘ₃−Ｙ−Ｘ₄−を、Ｘ₂、Ｘ₄各々は、−ＮＨ−、または−Ｏ−を、Ｘ₃は、−ＣＯＮＨ−、−ＳＯ₂ＮＨ−、−ＣＨ₂ＮＨ−、−ＮＨＣＯ−、または−ＮＨＳＯ₂−を、Ｙは、アルキレン基、アルケニレン基、またはアリーレン基を、Ｚは、−ＳＯ₃Ｍ、または−ＣＯＯＭを、Ｒ₁は、複素環残基、または芳香族環残基を、Ｌは、−Ｏ−Ｒ₂、−ＮＨ−Ｒ₂、ハロゲン基、−Ｘ₁−Ｒ₁または、−Ｘ₂−Ｙ−Ｚを、Ｒ₂は、Ｈ、アルキル基、またはアルケニル基を、Ｍは、１〜３価のカチオンの一当量を、表す。

In formula (1), X _1, -NH -, - O -, - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH- or -X ₃ -Y-X ₄ - a, X _2, X ₄ each, -NH-, or -O-, X _{3 is, -CONH -, - SO 2 NH} -, - CH 2 NH -, - NHCO-, or -NHSO ₂ - Y is an alkylene group, alkenylene group or arylene group, Z is —SO ₃ M or —COOM, R ₁ is a heterocyclic residue or an aromatic ring residue, and L is — O—R ₂ , —NH—R ₂ , a halogen group, —X ₁ —R ₁ or —X ₂ —YZ, R ₂ is H, an alkyl group, or an alkenyl group; One equivalent of a trivalent cation is represented.

式（２）中、Ｒは分枝を有することがある炭素数８から１６のアルキル基、アルキレン基またはアルケニレン基であって、ＰＯはプロピレンオキシ基、ＥＯはエチレンオキシ基を表し、ｎは４〜１２の整数、ｍは１〜１２の整数を表し、ＰＯとＥＯはランダムであってもブロックであってもよい。

In the formula (2), R is an alkyl group having 8 to 16 carbon atoms, an alkylene group or an alkenylene group which may have a branch, PO represents a propyleneoxy group, EO represents an ethyleneoxy group, and n represents 4 An integer of -12, m represents an integer of 1-12, and PO and EO may be random or block.

  The ink for ink-jet recording of the present invention is excellent in storage stability and ejection stability, has high color development on plain paper and glossy paper, has fixing properties in addition to sufficient gloss on glossy paper, This is due to the result of intensive studies in view of the demand for characteristics such as excellent ink ejection stability.

  The ink for inkjet recording of the present invention contains water, a pigment, a polymer for dispersing the pigment, a pigment derivative represented by formula (1), and a compound represented by formula (2). It is characterized by.

  Further, the pigment derivative represented by the formula (1) is present on the surface of the pigment. The pigment derivative represented by the formula (1) can exhibit its characteristics by being present on the surface of the pigment. In other words, it prevents crystal growth of almost all organic pigments in the ink system, exhibits a remarkable improvement effect on the resulting aggregation, and remarkably improves the fluidity of the ink. In this respect, the ink suitability can be improved, for example, an excellent film can be obtained. In addition, the polymer is polymerized with 50% by weight or more of benzyl acrylate and 15% by weight or less of (meth) acrylic acid as constituents, and has an acid value of 50 mgKOH / g or more and 120 mgKOH / g or less, and a weight average The molecular weight is preferably 20000 or more and 120,000 or less.

  If benzyl acrylate is less than 50% by weight, the fixability is lowered, so the preferred range is 50% by weight or more, but the case of less than 50% by weight is not denied. More preferably, it is 60 weight% or more, More preferably, it is 70 weight% or more. Polymerization with 15% by weight or less of (meth) acrylic acid is preferable. However, if it exceeds 15% by weight, the color developability of the inkjet ink on plain paper tends to decrease, but polymerization exceeding 15% by weight is likely to occur. A more preferable range is not more than 10% by weight. Further, when methacrylic acid and acrylic acid are compared, it is more preferable to use acrylic acid from the viewpoint of fixability.

  When the acid value of the polymer is less than 50 mgKOH / g, dispersion stability cannot be obtained, and when it exceeds 120 mgKOH / g, the color developability of plain paper is lowered. Further, when the weight average molecular weight is less than 20000, the long-term storage stability, thermal stability and fixability as an inkjet ink are deteriorated, and when it exceeds 120,000, the viscosity as an inkjet ink is increased and the dispersion stability is deteriorated. There is a tendency that the ejection stability further decreases.

  In the compound represented by the formula (2), R is preferably an alkyl group, an alkylene group, or an alkenylene group having 8 to 16 carbon atoms that may have a branch. When the number of carbon atoms is less than 8, glossiness on glossy paper is difficult to obtain. On the other hand, if it exceeds 16, a large amount of ethyleneoxy group is required to improve the solubility in water. However, if this is done, foaming tends to occur and ink jet dot loss tends to occur. Color developability on paper is also reduced. n is preferably from 4 to 12, but if it is less than 4, the glossiness on glossy paper is difficult to improve, and if it exceeds 12, an increased amount of ethyleneoxy group is required to improve the solubility in water. In this case, bubbles are easily generated, ink-jet dots are easily lost, and color developability on plain paper is also reduced. m is 1 to 12, but if it is less than 1, the solubility in water is lowered, so the addition amount is limited and glossiness of glossy paper cannot be obtained. On the other hand, if it exceeds 12, bubbles are likely to be formed, ink-jet dots are likely to be lost, and color developability on plain paper is also reduced. The addition of propyleneoxy group and ethyleneoxy group to the alkyl group may be random or block, but after adding propyleneoxy to the alkyl group in block, the structure in which ethyleneoxy is added in block is Random addition or addition of propyleneoxy to a block after adding ethyleneoxy to the alkyl group is preferable because glossiness on glossy paper improves and color developability on plain paper also improves.

  The pigment used in the present invention is, for example, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, copper oxide, iron oxide (C CI pigment black 11), metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1), but carbon black has a relatively low specific gravity and is difficult to settle in water for inkjet use. Is preferred. Further, for color use, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 74, 81, 83 (Disazo Yellow HR), 93, 94, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 128, 138, 153, 180, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (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, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (Quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 56 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc. can be used.

  The added amount of the pigment is preferably 0.5% by weight to 30% by weight, but more preferably 1.0% by weight to 12% by weight. If the addition amount is 0.5% by weight or less, the print density cannot be secured. If the addition amount is 30% by weight or more, the viscosity of the ink increases and the structural property is generated in the viscosity characteristics, and the ejection stability of the ink from the inkjet head is reduced. It tends to get worse.

  Examples of the pigment of the ink for inkjet recording of the present invention include C.I. I. Black 7, C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 6, C.I. I. Pigment green 36, C.I. I. Pigment red 122, C.I. I. Pigment red 177, C.I. I. Pigment red 254, C.I. I. Pigment violet 19, C.I. I. In the case of pigments other than yellow, such as CI Pigment Violet 23, the dispersion is performed using a polymer having an average particle size of 90 nm or less and an acid value of 50 mgKOH / g or more and 100 mgKOH / g or less. This is preferable from the viewpoint of providing an ink for ink jet recording which has excellent properties and has both high color development on plain paper and glossy paper and high gloss on glossy paper. When the average particle size exceeds 90 nm, the gloss on glossy paper decreases. Moreover, dispersion becomes unstable when the acid value is less than 50 mgKOH / g. Furthermore, when the acid value exceeds 100 mgKOH / g, the color developability on plain paper decreases. A more preferred acid value is 60 mgKOH / g to 100 mgKOH / g.

  In addition, the pigment of the inkjet recording ink of the present invention may be, for example, C.I. I. Pigment yellow 55, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 79, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138C. I. Pigment yellow 139, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 156, C.I. I. Pigment yellow 175 and C.I. I. In the case of a yellow pigment such as CI Pigment Yellow 180, it is possible to achieve storage stability by using a polymer having an average particle size of 20 nm to 110 nm and an acid value of 50 mgKOH / g to 120 mgKOH / g. This is preferable from the viewpoint of providing an ink for ink jet recording which has excellent properties and ejection stability, and has both high color developability on plain paper and glossy paper and high gloss on glossy paper. When the average particle size is less than 20 nm, the light resistance deteriorates. When the average particle size exceeds 110 nm, the color developability on plain paper decreases. Further, when the acid value is less than 50 mgKOH / g, the dispersion becomes unstable, and when the acid value exceeds 120 mgKOH / g, the color developability on plain paper decreases.

  The polymer used for dispersion of the pigment in the present invention is a commercially available styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer, polyethylene glycol ( It is also possible to use a combination of one or more selected from a (meth) acrylate- (meth) acrylic acid copolymer, a vinyl acetate-maleic acid copolymer, a styrene-maleic acid copolymer, and the like. However, it is preferable that at least 80% or more of the constituent components of the polymer are obtained by copolymerization of acrylate and acrylic acid.

  Examples of acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl carbitol acrylate, phenol EO-modified acrylate, N-vinyl pyrrolidone, Commercially available acrylates such as isobornyl acrylate, benzyl acrylate, paracumylphenol EO-modified acrylate, 2-hydroxyethyl-3-phenoxypropyl acrylate can be used. Further, ω-carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, acrylic acid dimer, or the like can be used instead of acrylic acid.

  Moreover, it is preferable that the dispersion method using the polymer used by this invention is the phase inversion emulsification in water so that a polymer may cover a pigment. By using the phase inversion emulsification method, the ink becomes stable and the color developability of plain paper is improved.

  In addition, the ink of the present invention has 2, 4, 7, 9-tetramethyl-5-decyne-4, 7-diol, 3,6-dimethyl-4-octyne-3, 6-diol, 2, 4, 7 , 9-tetramethyl-5-decyne-4,7-diol alkylene oxide adduct and 3,6-dimethyl-4-octyne-3, 6-diol alkylene oxide adduct The amount added is preferably 0.05% by weight to 1% by weight. If it is less than 0.05% by weight, bleeding on plain paper increases, which is not preferable. On the other hand, if it exceeds 1% by weight, the storage stability as an ink-jet ink deteriorates and long-term storage becomes difficult. More preferably, it is 0.1 weight% or more and 0.7 weight% or less.

  2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5 -An alkylene oxide adduct of decyne-4,7-diol is commercially available, Surfinol 104, Surfinol 82, Surfinol 2502, Surfinol 420, Surfinol 440, Surfinol 465, Surfinol manufactured by Nissin Chemical Co., Ltd. 485, acetylenol EOO, acetylenol E40, acetylenol E100 manufactured by Kawaken Fine Chemical Co., Ltd. and the like.

  The ink of the present invention preferably contains 1,2-alkylene glycol. Among 1,2-alkylene glycols, 1,2-hexanediol and 4-methyl-1,2-pentanediol are particularly preferable, improving the ejection stability of inkjet ink and reducing bleeding when printed on plain paper. To do.

  The ink of the present invention is one kind selected from di (tri) ethylene glycol monobutyl ether, (di) propylene glycol monobutyl ether, di (tri) ethylene glycol monopentyl ether and di (tri) ethylene glycol monohexyl ether. It is preferable to comprise the above. Bleeding when printing on plain paper by the inkjet method is further reduced, and the print quality is improved.

  The ink of the present invention preferably comprises 2-butyl-2-ethyl-1,3-propanediol. Glossiness on glossy paper is improved, and color development on plain paper is improved.

  Moreover, although the polymer in this invention has a carboxyl group, it is preferable to comprise triethanolamine and / or tripropanolamine as the counter ion. By using triethanolamine and / or tripropanolamine, clogging of the inkjet ink is less likely to occur even in a dry state.

  As a method for polymerizing the polymer of the present invention, an alcohol solvent, a ketone solvent, an ether solvent, or a glycol ether solvent can be used as a solvent. However, since it is an aqueous pigment dispersion, it is necessary to be able to remove the above-mentioned solvent later. Therefore, the following can be used as such a solvent. Examples of the alcohol solvent include methanol, ethanol, isopropanol, 1-butanol, tertiary butanol, isobutanol, diacetone alcohol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of ether solvents include dibutyl ether, tetrahydrofuran, dioxane and the like. Furthermore, examples of glycol ethers include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, and butyl cellosolve.

  Moreover, as a radical polymerization initiator for polymerizing a polymer, t-butyl peroxy (2-ethylhexanoate), di-t-butyl peroxide, t-butyl peroxybenzoate, t-butyl peroxyoct Organic peroxides such as ate, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2′-azobisbutyrate, 2, Azo compounds such as 2′-azobis (2-methylbutyronitrile), potassium persulfate, sodium persulfate, and the like can be used, but are not limited to these, and start other than the above as long as radical polymerization is possible. An agent can also be used. The amount of radical polymerization initiator used is preferably 0.01 mol% or more and 5 mol% or less with respect to the monomer used in the polymerization. The polymerization temperature is not particularly limited, but is usually in the range of 30 ° C to 100 ° C, and preferably in the range of 40 ° C to 90 ° C. When the polymerization temperature is too low, it is necessary to take a long time for the polymerization of the monomer, and in some cases, the polymerization rate may decrease and a large amount of monomer may remain.

  In addition, the ink of the present invention contains one or more selected from glycerin, trimethylolethane, trimethylolpropane, tetracarbon sugar, pentose sugar and hexose sugar in order to make ink jet clogging less likely. It is preferable to become.

  In the present invention, a dispersant, a surface tension adjusting agent or a penetrating agent (surfactant), a wetting and drying preventing agent, an antiseptic, a bactericidal agent, a pH adjusting agent, a rust preventing agent, a moisturizing agent and other additives are added as necessary. An agent may be used. These may be used alone or in combination of two or more.

  Next, as a method for producing the inkjet ink of the present invention, for example, the polymer composition for inkjet ink of the present invention, an aqueous medium, an alkali such as sodium hydroxide is emulsified by high-speed stirring, and a pigment or the like is further added. And a method of strongly dispersing with a disper or the like. Further, if necessary, a method of dispersing with a three-roll mill or the like, dispersing the obtained pigment slurry to a predetermined particle size with a high-pressure disperser or the like, and then removing the organic solvent or the like from the obtained pigment dispersion Etc. may be performed.

  The above-mentioned high-pressure disperser is not particularly limited, and examples thereof include a microfluidizer (Microfluidics), an optimizer (Sugino Machine), a wet jet mill (Genus), and a nanomizer (SG Engineering). It is done.

  The pressure at the time of dispersing with the above-described high-pressure disperser may be any as long as it can reach the desired pigment particle diameter, but is preferably 100 MPa to 300 MPa. If it is less than 100 MPa, the dispersed particle size tends to be large, and it takes time to disperse, and unless the number of passes is extremely increased, a stable dispersion is difficult to obtain, which is not economical. Moreover, when it exceeds 300 MPa, it is easy to become overdispersed, and it is difficult to obtain the stability of the dispersion. If the desired pigment particle diameter cannot be reached, the dispersion may be carried out by increasing the number of dispersions or increasing the pressure within the aforementioned pressure range.

  In addition, in the method for producing an ink-jet ink of the present invention, an alkali solution is added to the above-described polymer composition for ink-jet ink that has been polymerized and heated, and then the solvent is removed and replaced with ion-exchanged water or the like. You may use the polymer composition solution for inkjet inks.

  Further, the solvent for the above-described ink-jet ink polymer that has been polymerized is removed by distillation under reduced pressure, the solid matter of the obtained ink-jet ink polymer is crushed, and ion-exchanged water, an alkali solution, etc. are added and dissolved by heating, You may use the polymer solution for inkjet inks obtained. In this case, thereafter, it is not necessary to remove the organic solvent and the like from the obtained pigment dispersion.

  Examples of the alkali used in the alkali solution include tertiary alkanolamines such as triethanolamine and tripropanolamine, alkylalkanolamines, inorganic bases such as sodium hydroxide, potassium hydroxide, and lithium hydroxide. It is done.

(Example)
The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples, and various modifications can be made without departing from the gist of the present invention.

  The inside of a 2000 ml separable flask equipped with a stirrer, a reflux tube, a thermometer, and a dropping funnel was purged with nitrogen, and then 200.0 parts by weight of diethylene glycol monomethyl ether was placed in the separable flask and heated to 80 ° C. while stirring. . Next, 200.0 parts by weight of diethylene glycol monomethyl ether, 486.0 parts by weight of benzyl acrylate, 46.8 parts by weight of acrylic acid, and 3.0 parts by weight of t-butylperoxy (2-ethylhexanoate) are placed in the dropping funnel. The reaction was conducted dropwise at 80 ° C. over 4 hours in a separable flask. After completion of the dropwise addition, the mixture was kept at 80 ° C. for 1 hour, 0.6 parts by weight of t-butylperoxy (2-ethylhexanoate) was added, and further reacted at 80 ° C. for 1 hour. Thereafter, diethylene glycol monomethyl ether was removed by distillation under reduced pressure. Then, 560.0 parts by weight of methyl ethyl ketone was added to obtain a polymer composition solution having a resin solid content of 50%. After taking a part of the polymer composition solution thus obtained and drying for 1 hour in an oven at 105 ° C., the acid value of the solid of the obtained polymer composition is 60 mgKOH / g, The weight average molecular weight was 49000.

  Subsequently, 1.0 part of a pigment derivative represented by the formula (3) having copper phthalocyanine as an organic dye residue (hereinafter sometimes referred to as “pigment derivative (3)”), C.I. I. 9.0 parts of Pigment Blue 15: 4, 20 parts of ethylene glycol, and 100 parts of sodium sulfate were mixed and kneaded at 50 ° C. to 70 ° C. for 10 hours. After the kneaded material is dispersed in warm water, it is subjected to surface treatment by filtration and washing. I. Pigment Blue 15: 4 was obtained.

  Next, 3.0 parts by weight of 30% aqueous sodium hydroxide solution was added to 120.0 parts by weight of the polymer composition solution, stirred for 5 minutes with a high-speed disper, and further subjected to surface treatment. I. 480.0 parts by weight of Pigment Blue 15: 4 paste having a pigment concentration of 30% was added and stirred with a high-speed disperser for 1.5 hours to obtain a pigment-dispersed slurry. Then, the pigment dispersion slurry was continuously dispersed 10 times at a pressure of 200 MPa with an ultrahigh pressure homogenizer (Microfluidizer, manufactured by Mizuho Kogyo Co., Ltd.) to obtain a pigment dispersion.

  Further, methyl ethyl ketone and a part of water were distilled off from the pigment dispersion thus obtained by vacuum distillation using an evaporator, and centrifuged at 5000 rpm for 30 minutes with a centrifuge (05P-21, manufactured by Hitachi, Ltd.). Then, ion-exchanged water was added so that the pigment concentration was 15% by weight to prepare a pigment dispersion. And it filtered under pressure using a 5 micrometer membrane filter (made by Advantech). Thereafter, ink jet inks having the ink composition 1 shown in Table 2 were prepared. In addition, about the compound represented by Formula (2), the substance which has the block structure added in the order of PO and EO whose R is a nonyl group, n is 7, and m is 4, was used.

  C.I. surface-treated with a pigment derivative represented by the formula (4) (hereinafter also referred to as “pigment derivative (4)”). I. An inkjet ink having the ink composition 2 shown in Table 2 was prepared in the same manner as in Example 1 except that Pigment Red 255 was used to prepare a pigment dispersion.

  C. C. surface-treated with a pigment derivative represented by the formula (5) (hereinafter sometimes referred to as “pigment derivative (5)”). I. An inkjet ink having the ink composition 3 shown in Table 2 was prepared in the same manner as in Example 1 except that Pigment Yellow 74 was used to prepare a pigment dispersion.

  1.0 part of a pigment derivative (3) obtained using the same method as in Example 1, C.I. I. 9.0 parts of Pigment Blue 15: 3, 20 parts of ethylene glycol and 100 parts of sodium sulfate were mixed and kneaded at 50 ° C. to 70 ° C. for 10 hours. After the kneaded material is dispersed in warm water, it is subjected to surface treatment by filtration and washing. I. Pigment Blue 15: 3 was obtained.

  Subsequently, the inside of a 2000 ml separable flask equipped with a stirrer, a reflux tube, a thermometer, and a dropping funnel was purged with nitrogen, and then 200.0 parts by weight of diethylene glycol monomethyl ether was placed in the separable flask and stirred at 80 ° C. The temperature rose. Next, 200.0 parts by weight of diethylene glycol monomethyl ether, 486.0 parts by weight of benzyl acrylate, 36.0 parts by weight of acrylic acid, and 5.9 parts by weight of t-butylperoxy (2-ethylhexanoate) are placed in the dropping funnel. The reaction was conducted dropwise at 80 ° C. over 4 hours in a separable flask. After completion of the dropwise addition, the mixture was kept at 80 ° C. for 1 hour, 0.6 parts by weight of t-butylperoxy (2-ethylhexanoate) was added, and further reacted at 80 ° C. for 1 hour. Thereafter, diethylene glycol monomethyl ether was removed by distillation under reduced pressure. Then, 560.0 parts by weight of methyl ethyl ketone was added to obtain a polymer composition solution having a resin solid content of 50%. After taking a part of the polymer composition solution thus obtained and drying for 1 hour in a high-temperature dryer at 105 ° C., the acid value of the solid matter of the polymer composition obtained is 95 mgKOH / g, The weight average molecular weight was 26000.

  Thereafter, a pigment dispersion was prepared using the same method as in Example 1, and ink jet inks having the ink composition 4 shown in Table 2 were prepared. For compound (2), a substance having a block structure in which R is a decyl group, n is 6, and m is 4 and added in the order of EO and PO was used.

  C. I. Pigment Blue 15: 3 instead of C.I. I. The same procedure as in Example 4 was conducted except that Pigment Violet 19 was replaced with Pigment Derivative (3) and Pigment Derivative (4), and an ink jet ink of Ink Composition 5 shown in Table 2 was produced.

  C. I. Pigment Blue 15: 3 instead of C.I. I. The same procedure as in Example 4 was conducted except that Pigment Yellow 98 was replaced with Pigment Derivative (3) and Pigment Derivative (3), and ink jet inks having the ink composition 6 shown in Table 2 were prepared.

  Except that n of the compound (2) was changed to 9 and m was changed to 5, it was carried out in the same manner as in Example 1, and ink jet inks having the ink composition 7 shown in Table 2 were prepared.

  An ink jet ink having an ink composition 8 shown in Table 2 was prepared in the same manner as in Example 1 except that R of the compound (2) was changed to a dodecyl group, n was changed to 5, and m was changed to 6.

  An ink-jet ink having an ink composition 9 shown in Table 2 was prepared in the same manner as in Example 1 except that 70.0 parts by weight of acrylic acid was used instead of 46.8 parts by weight of acrylic acid. In addition, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC high temperature drier, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 100 mgKOH / g, and is a weight average. The molecular weight was 31000.

  Ink of ink composition 10 shown in Table 2 is carried out in the same manner as in Example 1 except that the addition form of PO and EO is changed to a substance having a random structure, where n is 7 and m is 4 in compound (2). Ink was made. In addition, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC high heat dryer, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 55 mgKOH / g, and is a weight average. The molecular weight was 48,000.

(Comparative Example 1)
The same procedure as in Example 1 was conducted except that the pigment derivative (3) was not added and the pigment surface treatment was not performed, and ink jet inks having the ink composition 11 shown in Table 2 were prepared.

(Comparative Example 2)
An ink jet ink having an ink composition 12 shown in Table 2 was prepared in the same manner as in Example 2 except that the pigment derivative (4) was not added and the pigment surface treatment was not performed.

(Comparative Example 3)
The same procedure as in Example 3 was conducted except that the pigment derivative (5) was not added and the pigment surface treatment was not performed, and ink jet inks having the ink composition 13 shown in Table 2 were prepared.

(Comparative Example 4)
An inkjet ink having the ink composition 14 shown in Table 2 was prepared in the same manner as in Example 1 except that R of the compound (2) was changed to a pentyl group, n was changed to 3, and m was changed to 2.

(Comparative Example 5)
An inkjet ink having the ink composition 15 shown in Table 2 was prepared in the same manner as in Example 2 except that R of the compound (2) was changed to a pentyl group, n was changed to 3, and m was changed to 2.

(Comparative Example 6)
An inkjet ink having the ink composition 16 shown in Table 2 was prepared in the same manner as in Example 3 except that R of the compound (2) was changed to a pentyl group, n was changed to 3, and m was changed to 2.

(Comparative Example 7)
An ink-jet ink having an ink composition 17 shown in Table 2 was prepared in the same manner as in Example 1 except that 30.0 parts by weight of acrylic acid was used instead of 46.8 parts by weight of acrylic acid. In addition, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC high temperature drier, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 40 mgKOH / g, and is a weight average. The molecular weight was 28000.

(Comparative Example 8)
The same procedure as in Example 1 was carried out except that 50.0 parts by weight of acrylic acid and 40.0 parts by weight of methacrylic acid were used instead of 46.8 parts by weight of acrylic acid. Created ink. In addition, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC high temperature drier, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 110 mgKOH / g, and is a weight average. The molecular weight was 110,000.

(Comparative Example 9)
An ink jet ink having an ink composition 19 shown in Table 2 was prepared in the same manner as in Example 1 except that the acrylic acid was changed to 40.0 parts by weight and changed to 100.0 parts by weight. In addition, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC high heat dryer, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 130 mgKOH / g, and is a weight average. The molecular weight was 50,000.

(Comparative Example 10)
The same procedure as in Example 1 was conducted except that the amount of t-butylperoxy (2-ethylhexanoate) added was changed from 3.6 parts by weight to 9.1 parts by weight. Inkjet ink was prepared. In addition, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC high heat dryer, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 60 mgKOH / g, and is a weight average. The molecular weight was 18000.

(Comparative Example 11)
The same procedure as in Example 1 was conducted except that the amount of t-butylperoxy (2-ethylhexanoate) added was changed from 3.6 parts by weight to 1.8 parts by weight. Inkjet ink was prepared. In addition, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC high heat dryer, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 60 mgKOH / g, and is a weight average. The molecular weight was 130,000.

(Evaluation Test 1: Evaluation Method for Colorability of Plain Paper)
The inkjet ink according to Examples 1 to 10 and Comparative Examples 1 to 11 was solid-printed on XeroxP paper (manufactured by Fuji Xerox Co., Ltd.) using an inkjet printer (EM-930C, manufactured by Seiko Epson Corporation), and a test specimen was obtained. Obtained. The print mode was paper: plain paper, print quality: super fine, color correction: none, print direction: bidirectional. And it is by measuring the OD value of each color using GRETAGMACBETH SPECTROSCANSP50 (made by Gretag (USA)). The results are shown in Table 1 as OD values.

(Evaluation Test 2: Glossiness Evaluation Method)
The inkjet inks according to Examples 1 to 10 and Comparative Examples 1 to 11 were solid-printed on photographic paper <glossy> (Seiko Epson Corporation) with an inkjet printer (EM-930C, manufactured by Seiko Epson Corporation), and a test specimen Got. The print mode was paper: photo print paper, print quality: photo, color correction: none, print direction: bidirectional. The 20 degree gloss of this test specimen was measured with a gloss meter (HG-268, manufactured by Suga Test Instruments Co., Ltd.). The results are shown in Table 1.

(Evaluation Test 3: Dispersibility Evaluation Method)
The average particle diameter of the particles in the inkjet inks according to Examples 1 to 10 and Comparative Examples 1 to 11 was measured with a laser particle size analyzer (Zeta Sizer 3000, manufactured by Malvern, UK). The results are shown in Table 1.

(Evaluation Test 4: Evaluation Method of Storage Stability)
The initial viscosity of the pigment dispersion for inkjet ink used in Examples 1 to 10 and Comparative Examples 1 to 11 and the viscosity after standing at 70 ° C. for 1 week were measured using a rolling ball viscometer (AMVn, Anton Paar (Germany). )). The results are shown in Table 1 as storage stability: viscosity (mPa · s) / initial viscosity (mPa · s) after standing at 70 ° C. for 1 week. Table 1 also shows the monomer composition, the polymerization initiator and the pigment, and the inkjet ink composition used when the inkjet ink was produced.

In addition, the symbol shown in Table 1 and Table 2 is as follows.
BZA: benzyl acrylate AA: acrylic acid MAA: methacrylic acid BPEH: t-butylperoxy (2-ethylhexanoate)
PB15: 3: C.I. I. Pigment Blue 15: 3
PB15: 4: C.I. I. Pigment Blue 15: 4
PR255: C.I. I. Pigment Red 255
PV19: C.I. I. Pigment Violet 19
PY74: C.I. I. Pigment Yellow 74
PY98: C.I. I. Pigment Yellow 98
DEGmBE: diethylene glycol monobutyl ether TEGmBE: triethylene glycol monobutyl ether PGmBE: propylene glycol monobutyl ether DPGmBE: dipropylene glycol monobutyl ether BEPD: 2-butyl-2-ethyl-1,3-propanediol 1,2-HD: 1,2 -Hexanediol TMP: Trimethylolpropane

  In Table 1, BZA, AA, MAA, BPEH, PB15: 3, PB15: 4, PR255, PV19, PY74 and PY98 are shown in parts by weight. Moreover, in Table 2, it shows by weight% of each component. Table 1 also shows the ratio of the number of carbons of R in formula (2), the number of moles of added propyleneoxy PO (n), and the number of moles of added ethyleneoxyEO (m). The PO and EO addition forms in formula (2) indicate whether propyleneoxy PO and ethyleneoxy EO are added to R in a block or random manner. In addition, in the case of block addition, the PO and EO addition order is shown as POEO when propyleneoxyPO is added to R first, and as EOPO when ethyleneoxyEO is added first to the alkyl group R.

  As can be seen from the results in Table 1, when the inkjet inks according to Examples 1 to 10 are used, the evaluation tests 1 to 4 are all good results, but when the inkjet inks according to Comparative Examples 1 to 11 are used. The evaluation tests 1 to 4 do not give good results in any one or a plurality of items.

Claims (7)

An ink for ink jet recording comprising water, a pigment, a polymer for dispersing the pigment, a pigment derivative represented by formula (1), and a compound represented by formula (2).

In formula (1), X _1, -NH -, - O -, - CONH -, - SO 2 NH -, - CH 2 NH -, - CH 2 NHCOCH 2 NH- or -X ₃ -Y-X ₄ - a, X _2, X ₄ each, -NH-, or -O-, X _{3 is, -CONH -, - SO 2 NH} -, - CH 2 NH -, - NHCO-, or -NHSO ₂ - Y is an alkylene group, alkenylene group or arylene group, Z is —SO ₃ M or —COOM, R ₁ is a heterocyclic residue or an aromatic ring residue, and L is — O—R ₂ , —NH—R ₂ , a halogen group, —X ₁ —R ₁ or —X ₂ —YZ, R ₂ is H, an alkyl group, or an alkenyl group; One equivalent of a trivalent cation is represented.

In the formula (2), R is an alkyl group having 8 to 16 carbon atoms, an alkylene group or an alkenylene group which may have a branch, PO represents a propyleneoxy group, EO represents an ethyleneoxy group, and n represents 4 An integer of -12, m represents an integer of 1-12, and PO and EO may be random or block.   The ink for inkjet recording according to claim 1, wherein the pigment derivative represented by the formula (1) is present on the surface of the pigment.   The polymer is polymerized with at least 50% by weight or more of benzyl acrylate and 15% by weight or less (meth) acrylic acid as its constituent components, and has an acid value of 50 mgKOH / g or more and 120 mgKOH / g or less, and a weight average molecular weight. The ink for inkjet recording according to claim 1, wherein is from 20,000 to 120,000.   0.05% to 1% by weight of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4,7 The ink for inkjet recording according to any one of claims 1 to 3, further comprising at least one selected from alkylene oxide adducts of diols.   The ink for inkjet recording according to claim 1, comprising 1,2-alkylene glycol.   The ink for inkjet recording according to any one of claims 1 to 5, comprising at least one selected from di (tri) ethylene glycol monobutyl ether and (di) propylene glycol monobutyl ether.   The ink for ink jet recording according to any one of claims 1 to 6, comprising 2-butyl-2-ethyl-1,3-propanediol.