JP2007099913A - Ink for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide inkjet recording ink having excellent storage stability and ejection stability, while achieving good color development on plain paper or glossy paper and high gloss on glossy paper. <P>SOLUTION: The inkjet recording ink contains water and a pigment dispersed therein by using a polymer having an acid number of 50-120 mgKOH/g and a weight-average molecular weight of 20,000-120,000, and containing ≥50 wt.% benzyl acrylate and ≤15 wt.% (meth)acrylic acid polymerized as a constitutional component of the polymer. The invention further provides ink containing at least one kind of fine particles of a resin containing ≥50 wt.% benzyl acrylate and ≤15 wt.% (meth)acrylic acid polymerized as a constitutional component of the polymer and having an acid number of 50-120 mgKOH/g and a weight-average molecular weight of 20,000-120,000 in the form of a resin emulsion. <P>COPYRIGHT: (C)2007,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 color developability on plain paper and glossy paper, and high glossiness and fixability on glossy paper.

  Many conventional inks for ink jet recording use dyes as coloring materials, but those using pigments have recently started to spread. In recent years, it has become increasingly popular to create so-called photographic image recordings using an ink-jet recording apparatus and post them indoors and outdoors. Is advantageous in that printed images having various weather resistance such as light resistance, gas resistance, and water resistance can be obtained as compared with dyes used as coloring materials.

  In the ink using a pigment, as a means for dispersing the pigment in water, a method using a surfactant (see Patent Document 1) and a method using a dispersion polymer having a hydrophobic part and a hydrophilic part (see Patent Document 2) are known. ing. Also, a method of coating the surface of the pigment with a polymer has been studied, and examples thereof include a method using a phase inversion emulsification reaction or an acid precipitation method (see Patent Document 3).

Japanese Patent Laid-Open No. 01-301760 Japanese Patent Laid-Open No. 06-306317 Japanese Patent Laid-Open No. 10-140065

  However, all of the above-mentioned pigment dispersion methods use a polymer containing styrene as a main constituent, so that the fixability is not so good, and there is a problem that yellowing easily occurs during long-term storage of printed matter. In addition, when a substance having a hydrophilic part and a hydrophobic part, such as a surfactant or glycol ether, is present in the ink, the adsorption and desorption from the pigment of the polymer tends to occur in a normal case, and the storage stability is inferior. Since ink reduces bleeding on paper, a substance having a hydrophilic part and a hydrophobic part such as a surfactant and glycol ether is necessary. Ink that does not use these substances has insufficient permeability to paper and is uniform. In order to perform printing, the type of paper is limited, and there is a problem that it tends to cause a decrease in the printed image.

  Further, for example, additives for improving print quality (acetylene glycol surfactants, acetylene alcohol surfactants, silicon surfactants, di (tri) ethylene glycol monobutyl ether or 1,2, -Alkylene glycol or a mixture thereof), long-term storage stability cannot be obtained, and in the case of pigment ink, the re-dissolvability is poor, so that the ink is dried and easily clogged with the nozzles of the inkjet head, The material such as an adhesive used for the substance constituting the material is attacked to lower the adhesive strength and lower the discharge reliability. In the worst case, the discharge is impossible.

  In addition, when a pigment dispersed with a general dispersing agent as described above is used, the residue of the dispersing agent remains in the ink system, and the dispersing agent does not contribute sufficiently to the dispersion, and the viscosity is released from the pigment. There was a problem of becoming expensive. When the viscosity 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.

  In the inkjet recording ink of the present invention, water, at least 50% by weight or more of benzyl acrylate and 15% by weight or less (meth) acrylic acid are polymerized as a polymer component, and an acid value of 50 to 120 mgKOH / g is obtained. A pigment dispersed using a polymer having a weight average molecular weight of 20,000 or more and 120,000 or less, further comprising at least 50% by weight or more of benzyl acrylate and 15% by weight or less as a polymer component (Meth) acrylic acid is polymerized and contains at least one resin fine particle comprising a polymer having an acid value of 50 to 120 mgKOH / g and having a weight average molecular weight of 20,000 to 120,000 in the form of a resin emulsion. And

  The ink for ink jet recording of the present invention has excellent storage stability and ejection stability, and provides an ink jet recording ink having both high color developability on plain paper and glossy paper and high gloss on glossy paper. Have.

  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.

  In the inkjet recording ink of the present invention, water, 50% by weight or more of benzyl acrylate and 15% by weight or less of (meth) acrylic acid are polymerized as a polymer component, and an acid value of 50 to 120 mgKOH / g is obtained. And a pigment dispersed using a polymer having a weight average molecular weight of 20,000 to 120,000.

  In the present invention, a polymer in which 50% by weight or more of benzyl acrylate and 15% by weight or less of (meth) acrylic acid are polymerized is preferable. When 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. The benzyl acrylate is preferably 50% by weight or more, more preferably 60% by weight or more, and still more preferably 70% by weight or more. Polymerization with 15% by weight or less of (meth) acrylic acid is preferred. If it exceeds 15% by weight, the color developability of the inkjet ink on plain paper tends to decrease. However, it does not deny the case where it exceeds 15% by weight, and a more preferable range is 10% by weight or less. When methacrylic acid and acrylic acid are compared, it is more preferable to use acrylic acid from the viewpoint of fixability.

  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, 202, 209, 219, 254, . I. Pigment violet 19, 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.

  In the present invention, the addition amount of the pigment is preferably 0.5 to 30% by weight, more preferably 1.0 to 12% by weight. If the addition amount is 0.5% by weight or less, the print density cannot be secured, and if the addition amount is 30% by weight or more, the viscosity of the ink increases and structural viscosity is generated in the viscosity characteristics, and the ejection stability of the ink from the inkjet head 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 pigments 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 mg to 80 mg KOH / g, so that storage stability and ejection stability are improved. It is preferable from the viewpoint of providing an ink for ink jet recording which is excellent and has both high color developability 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 80 mgKOH / g, the color developability on plain paper decreases. A more preferred acid value is 50 to 70 mg KOH / g.

  Further, the pigment of the ink for ink jet recording of the present invention is, 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 yellow pigments such as CI Pigment Yellow 180, the dispersion is performed using a polymer having an average particle diameter of 20 to 110 nm and an acid value of 50 to 120 mgKOH / g. It is preferable from the viewpoint of providing an ink for ink jet recording which is excellent 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 ( 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 can also be used. However, it is preferable that at least 80% or more is a polymer obtained by copolymerization of acrylate and acrylic acid. Examples of the acrylate 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, and 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 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 the present invention, the polymer in which the pigment is dispersed preferably has a weight average molecular weight of 20,000 to 200,000. If the weight average molecular weight is less than 20,000, the long-term storage stability, thermal stability and fixability as an ink-jet ink will deteriorate, and if it exceeds 200,000, the viscosity as an ink-jet ink will increase and the dispersion stability will tend to deteriorate. There is also a tendency for the discharge stability to decrease.

  In the polymer polymerization method 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 the ether solvent include dibutyl ether, tetrahydrofuran, dioxane and the like. Furthermore, examples of the 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. As for the usage-amount of a radical polymerization initiator, 0.01-5 mol% is preferable with respect to the monomer used in the case of superposition | polymerization. The polymerization temperature is not particularly limited, but is usually in the range of 30 to 100 ° C, and preferably in the range of 40 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.

  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, ink clogging hardly occurs even in a dry state.

  Furthermore, the ink for inkjet recording of the present invention is a polymer having 50% by weight or more of benzyl acrylate and 15% by weight or less of (meth) acrylic acid as a polymer component, and having an acid value of 50 to 120 mgKOH / g. It is characterized in that at least one kind of resin fine particles composed of a polymer having an average molecular weight of 20000 to 120,000 is further contained in the ink in the form of a resin emulsion.

  In the inkjet recording ink of the present invention, by further containing the resin emulsion, while maintaining a state excellent in storage stability and ejection stability, higher color developability on plain paper and glossy paper, and High glossiness and fixability on glossy paper can be obtained.

  In the present invention, as a means for improving the color developability and glossiness, there is a method of increasing the amount of the dispersant used for dispersing the pigment. This is not preferable because it may lead to a decrease in ink viscosity and a decrease in ejection reliability. On the other hand, when the resin fine particles made of the polymer are contained in the form of a resin emulsion, it is possible to effectively improve the color developability and glossiness without causing a decrease in the ejection reliability as described above. it can. Moreover, the effect of improving the weather resistance (light resistance and gas resistance) of the ink can be obtained by adding the resin emulsion.

  In the present invention, the polymer constituting the resin fine particles contained in the resin emulsion is preferably a polymer in which 50% by weight or more of benzyl acrylate and 15% by weight or less of (meth) acrylic acid are polymerized. When 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. The benzyl acrylate is preferably 50% by weight or more, more preferably 60% by weight or more, and still more preferably 70% by weight or more. Polymerization with 15% by weight or less of (meth) acrylic acid is preferred. If it exceeds 15% by weight, the color developability of the inkjet ink on plain paper tends to be lowered, but polymerization exceeding 15% by weight is not denied, and a more preferred range is 10% by weight or less. When methacrylic acid and acrylic acid are compared, it is more preferable to use acrylic acid from the viewpoint of fixability.

  In the present invention, when the main constituent color material of the ink is a pigment other than yellow, it is possible to use resin fine particles made of a polymer having an acid value of 50 mg to 80 mg KOH / g as the resin emulsion. In addition, it is preferable from the viewpoint of providing an ink for inkjet recording that has excellent ejection stability and has both high color developability on plain paper and glossy paper and high gloss on glossy paper. When the acid value is less than 50 mgKOH / g, the dispersion stability of the pigment is lowered, and when the acid value exceeds 80 mgKOH / g, the color developability on plain paper is lowered. A more preferred acid value is 50 to 70 mg KOH / g.

  In addition, when the main constituent color material of the ink is a yellow pigment, it is possible to use resin fine particles made of a polymer having an acid value of 50 to 120 mgKOH / g. It is more preferable from the viewpoint of realizing high glossiness and fixing property. When the acid value is less than 50 mgKOH / g, the dispersion stability of the pigment is lowered, and when the acid value exceeds 120 mgKOH / g, the color developability on plain paper is lowered.

  In the present invention, the polymer constituting the resin fine particles contained in the resin emulsion preferably has a weight average molecular weight of 20,000 to 200,000. If the weight average molecular weight is less than 20,000, the long-term storage stability, thermal stability and fixability as an ink-jet ink will deteriorate, and if it exceeds 200,000, the viscosity as an ink-jet ink will increase and the dispersion stability will tend to deteriorate. There is also a tendency for the discharge stability to decrease.

  In the ink for ink jet recording of the present invention, the constituent components of the polymer constituting the resin fine particles contained in the resin emulsion are the same as the constituent components of the polymer used for pigment dispersion. The polymer preferably contains 50% or more by weight. By using a polymer having the same component of 50% or more, the color developability and gloss can be effectively improved with a smaller amount, and the color developability of plain paper can be greatly improved.

  In the inkjet recording ink of the present invention, the average particle size of the resin fine particles contained in the resin emulsion is preferably 20 to 150 nm. If the average particle size is too small, it is difficult to obtain the effect of improving the color developability and glossiness. If it is too large, the color developability on plain paper and the glossiness on glossy paper tend to decrease. It is desirable to use in.

  In the ink for ink jet recording of the present invention, the resin fine particles contained in the resin emulsion are preferably contained in a range of 0.1 to 10% by weight with respect to the total amount of the ink. If the amount is too small, it is difficult to obtain the effect of improving the color developability and glossiness. If the amount is too large, the color developability on plain paper and glossiness on glossy paper tend to decrease. It is desirable to use in the above-mentioned range.

  In the present invention, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4, One or more selected from alkylene oxide adducts of 7,9-tetramethyl-5-decyne-4,7-diol and alkylene oxide adducts of 3,6-dimethyl-4-octyne-3,6-diol It is preferably contained in the ink. By using these pigments dispersed with the polymer of the present invention in combination, the ejection stability of the ink-jet ink is improved, and bleeding when printed on plain paper is reduced. The content is preferably 0.05 to 1% by weight based on the total amount of ink. If it is less than 0.05% by weight, bleeding on plain paper increases, and 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 to 0.7% by weight.

  2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5 One or more selected from alkylene oxide adducts of decyne-4,7-diol and alkylene oxide adducts of 3,6-dimethyl-4-octyne-3,6-diol are commercially available, Nissin Chemical Co., Ltd. Surfinol 104, Surfinol 82, Surfinol 2502, Surfinol 420, Surfinol 440, Surfinol 465, Surfinol 485, manufactured by Kawaken Fine Chemical Co., Ltd., acetylenol EOO, acetylenol E40, and acetylenol E100 are available.

  The ink of the present invention preferably contains 1,2-alkylene glycol. Among the 1,2-alkylene glycols, 1,2-hexanediol and 4-methyl-1,2-pentanediol are particularly preferable, and the pigment dispersed with the polymer of the present invention and the ejection stability of the inkjet ink by using these pigments are used. And the bleeding when printing on plain paper is reduced.

  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. By using the pigment dispersed with the polymer of the present invention and these glycol ethers, bleeding when printed on plain paper by the inkjet method is further reduced, and the printing quality is improved.

  Further, the ink of the present invention preferably contains 2-butyl-2-ethyl-1,3-propanediol, and a pigment formed by dispersing the polymer of the present invention and 2-butyl-2-ethyl-1 By using 3-propanediol, the glossiness on glossy paper is improved and the color development on plain paper is improved.

  Similarly, in order to make inkjet clogging difficult to occur, it is preferable to include one or more selected from glycerin, trimethylolethane, trimethylolpropane, tetrasaccharide, pentasaccharide and hexasaccharide.

  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 ink for ink jet recording of the present invention, for example, the polymer composition for ink for ink jet recording of the present invention, an aqueous medium, an alkali such as sodium hydroxide is emulsified by high speed stirring, and a pigment is further added. And the like, 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 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 (Nanomizer).

  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.

  Further, in the method for producing an ink for ink jet recording of the present invention, an alkali solution is added to the above-described polymer composition for ink for ink jet recording which has been polymerized and heated, and then the solvent is removed, and ion exchange water or the like. A polymer composition solution for ink jet recording ink substituted with may be used.

  Further, the solvent for the ink for ink-jet recording described above after polymerization is removed by distillation under reduced pressure, the solid matter of the polymer for ink-jet recording obtained is crushed, and ion-exchanged water, an alkali solution, etc. are added and heated. The polymer solution for ink for ink jet recording obtained by dissolving may be used. 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 aforementioned alkaline solution include tertiary alkyl alkanolamines such as triethanolamine and tripropanolamine, and inorganic bases such as sodium hydroxide, potassium hydroxide and lithium hydroxide.

(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.

[Preparation of resin emulsion]
[Resin emulsion A]
The inside of a 2000 ml separable flask equipped with a stirrer, reflux tube, thermometer, and 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, 483.0 parts by weight of benzyl acrylate, 50.4 parts by weight of acrylic acid, and 4.8 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, 0.8 parts by weight of t-butylperoxy (2-ethylhexanoate) was added, and the reaction was further carried out at 80 ° C. for 1 hour. Thereafter, diethylene glycol monomethyl ether was removed by distillation under reduced pressure. Then, 600.0 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 ignition dryer at 105 ° C., the acid value of the solid matter of the polymer composition obtained is 65 mgKOH / g, The weight average molecular weight was 34,000.

  Next, after removing the methyl ethyl ketone from the polymer composition solution thus prepared by vacuum distillation using an evaporator and cooling to room temperature, ion-exchanged water and 5% aqueous sodium hydroxide solution were added to the resin composition. A resin emulsion having a content of 40% by weight and a pH of 8 was obtained.

  The average particle size of this emulsion was 55 nm as measured with a laser particle size analyzer (Zeta Sizer 3000, Malvern).

[Resin emulsion B]
Resin emulsion B was prepared in the same manner as Resin Emulsion A except that instead of 50.4 parts by weight of acrylic acid, 13.2 parts by weight of methacrylic acid and 36.5 parts by weight of acrylic acid were used. In addition, after taking a part of the polymer composition solution and drying it with a high-temperature dryer at 105 ° C. for 1 hour, the acid value of the solid matter of the obtained polymer composition for inkjet ink was 60 mgKOH / g, and the weight average molecular weight was The average particle size of this emulsion was 62 nm.

[Resin emulsion C]
Resin emulsion C was prepared in the same manner as Resin Emulsion A except that 42.6 parts by weight of acrylic acid was used instead of 50.4 parts by weight of acrylic acid. Moreover, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC intense heat dryer, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 55 mgKOH / g, and a weight average molecular weight is The average particle size of this emulsion was 58 nm.

[Resin emulsion D]
Resin emulsion D was prepared in the same manner as Resin Emulsion A except that 77.5 parts by weight of acrylic acid was used instead of 50.4 parts by weight of acrylic acid. In addition, after taking a part of the polymer composition solution and drying for 1 hour with a high-temperature dryer at 105 ° C., the acid value of the solid matter of the obtained polymer composition for inkjet ink is 100 mgKOH / g, The average particle size of this emulsion was 48 nm.

[Resin Emulsion E]
Resin emulsion E was prepared in the same manner as Resin Emulsion A except that 93.0 parts by weight of acrylic acid was used instead of 50.4 parts by weight of acrylic acid. In addition, after taking a part of the polymer composition solution and drying for 1 hour in a high-temperature dryer at 105 ° C., the acid value of the solid matter of the obtained polymer composition for inkjet ink is 120 mgKOH / g, The average particle size of this emulsion was 43 nm.

[Resin emulsion F]
Resin emulsion F was prepared in the same manner as Resin Emulsion A except that 155.0 parts by weight of acrylic acid was used instead of 50.4 parts by weight of acrylic acid. Moreover, 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 200 mgKOH / g, and a weight average molecular weight Was 29000, and the average particle size of this emulsion was 38 nm.

[Resin emulsion G]
Similar to Resin Emulsion A except that 9.2 parts by weight of t-butylperoxy (2-ethylhexanoate) was used instead of 4.8 parts by weight of t-butylperoxy (2-ethylhexanoate). The resin emulsion G was prepared. Moreover, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC intense heat dryer, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 65 mgKOH / g, and a weight average molecular weight is The average particle size of this emulsion was 65 nm.

[Resin emulsion H]
Similar to Resin Emulsion A, except that 4.8 parts by weight of t-butylperoxy (2-ethylhexanoate) was replaced with 2.3 parts by weight of t-butylperoxy (2-ethylhexanoate). The resin emulsion G was prepared. Moreover, after taking a part of polymer composition solution and drying for 1 hour with a 105 degreeC intense heat dryer, the acid value of the solid substance of the obtained polymer composition for inkjet inks is 65 mgKOH / g, and a weight average molecular weight is The average particle size of this emulsion was 78 nm.

[Resin emulsion I]
The inside of a 2000 ml separable flask equipped with a stirrer, reflux tube, thermometer, and dropping funnel was purged with nitrogen, and then 300.0 parts by weight of ion-exchanged water and 1 part by weight of sodium lauryl sulfate were placed in the separable flask and stirred. The temperature was raised to 70 ° C. After dissolving 1.3 parts by weight of potassium persulfate as a polymerization initiator and dissolving, 150 parts by weight of ion exchange water, 1 part by weight of sodium lauryl sulfate, 7 parts by weight of acrylamide, 225 parts by weight of methyl methacrylate, and 78 parts by weight of butyl acrylate. , And 10 parts by weight of methacrylic acid, which has been stirred, are placed in a dropping funnel and dropped into a separable flask at 70 ° C. for 4 hours to be reacted. After completion of dropping, the mixture is further maintained at 70 ° C. for 3 hours. did. 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 obtained polymer composition is 75 mgKOH / g, The weight average molecular weight was 44,000.

  The polymer composition solution thus prepared was cooled to room temperature, and ion-exchanged water and 5% aqueous sodium hydroxide solution were added to obtain a resin emulsion having a resin content of 40% by weight and a pH of 8.

  The average particle size of this emulsion was 55 nm as measured with a laser particle size analyzer (Zeta Sizer 3000, Malvern).

  [Preparation of ink]

  In the same manner as for resin emulsion A, a polymer composition solution having a resin solid content of 50% was obtained.

  Next, 3.0 parts by weight of a 30% aqueous sodium hydroxide solution is added to 120.0 parts by weight of the polymer composition solution thus prepared, and the mixture is stirred with a high-speed disper for 5 minutes. Further, Cyanine Blue G- 480.0 parts by weight of 500 pure-A (CI PB15: 1; manufactured by Sanyo Dye Co., Ltd.) was added, and the mixture was stirred with a high-speed disper for 1 hour to obtain a pigment dispersion 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 by 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 pressure-filtered using the 2.5 micrometer membrane filter (made by Advantech).

  Thereafter, as shown in ink composition 1 in Table 3, the ink was mixed with various solvents including the resin emulsion A to prepare a desired ink for ink jet recording.

  Table 3 shows the same procedure as in Example 1 except that 50.4 parts by weight of acrylic acid was replaced with 13.2 parts by weight of methacrylic acid, 36.5 parts by weight of acrylic acid, and the resin emulsion used was B. An ink for ink jet recording of composition example 2 shown in FIG.

  Example except that 42.6 parts by weight of acrylic acid was used instead of 50.4 parts by weight of acrylic acid, and the resin used was B30% and C70% (both in terms of weight conversion ratio in the resin emulsion, hereinafter the same). 1 was carried out in the same manner as in Example 1, and an ink jet recording ink of Composition Example 3 shown in Table 3 was prepared.

  Composition Example 4 shown in Table 3 was carried out in the same manner as in Example 1 except that 77.5 parts by weight of acrylic acid was used instead of 50.4 parts by weight of acrylic acid, and the resin emulsion used was D50% and E50%. Ink jet recording ink was prepared.

  Instead of 480.0 parts by weight of Cyanine G-500 pure-A, the same as Example 1 except that 480.0 parts by weight of Pigment Violet GC227-A (CI PV19; manufactured by Sanyo Pigment Co., Ltd.) was used. Then, an ink for inkjet recording of Composition Example 9 shown in Table 3 was prepared.

  The same procedure as in Example 2 was performed except that 480.0 parts by weight of Pigment Violet GC227-A was used instead of 480.0 parts by weight of Cyanine G-500 pure-A. Inkjet recording of Composition Example 10 shown in Table 3 Ink was made.

  The same as Example 1 except that 480.0 parts by weight of Fast Yellow 7413-A (CI PY74; manufactured by Sanyo Dye Co., Ltd.) was used instead of 480.0 parts by weight of Cyanine G-500 pure-A. The ink for inkjet recording of the composition example 13 shown in Table 4 was produced.

  Inkjet recording of Composition Example 14 shown in Table 4 was carried out in the same manner as in Example 2 except that 480.0 parts by weight of Fast Yellow 7413-A was used instead of 480.0 parts by weight of Cyanine G-500 pure-A. Ink was made.

  Instead of 480.0 parts by weight of Cyanine G-500 pure-A, Monarch 800 (CI PBk7: manufactured by Cabot) was performed in the same manner as in Example 1 except that 480.0 parts by weight were used. An ink for ink-jet recording having the composition example 17 shown was prepared.

  Cyanine G-500 pure-A The same procedure as in Example 2 was conducted except that 480.0 parts by weight of Monarch 800 was replaced with 480.0 parts by weight, and an ink jet recording ink of Composition Example 18 shown in Table 4 was prepared. did.

(Comparative Example 1)
The same procedure as in Example 1 was conducted except that the resin emulsion to be used was F, and an ink for inkjet recording of Composition Example 5 shown in Table 3 was prepared.

(Comparative Example 2)
Except that G was used as the resin emulsion to be used, the same procedure as in Example 3 was carried out to prepare an ink jet recording ink of Composition Example 6 shown in Table 3.

(Comparative Example 3)
The same procedure as in Example 4 was conducted, except that the resin emulsion used was changed to G30% and H70%, and ink jet recording inks of Composition Example 7 shown in Table 3 were prepared.

(Comparative Example 4)
Except that the resin emulsion to be used was changed to I, the same procedure as in Example 2 was performed to prepare an inkjet recording ink of Composition Example 8 shown in Table 3.

(Comparative Example 5)
Except that F was used as the resin emulsion to be used, the same procedure as in Example 5 was carried out to prepare an ink for inkjet recording of Composition Example 11 shown in Table 4.

(Comparative Example 6)
The same procedure as in Example 6 was conducted, except that the resin emulsion used was changed to F30% and G70%, and an inkjet recording ink of Composition Example 12 shown in Table 4 was produced.

(Comparative Example 7)
Except that F was used as the resin emulsion to be used, the same procedure as in Example 7 was carried out to prepare an ink jet recording ink of Composition Example 15 shown in Table 4.

(Comparative Example 8)
The same procedure as in Example 8 was conducted, except that the resin emulsion used was F50% and G50%, and an inkjet recording ink of Composition Example 16 shown in Table 4 was produced.

(Comparative Example 9)
The same procedure as in Example 9 was conducted except that the resin emulsion used was F, and an ink jet recording ink of Composition Example 19 shown in Table 4 was produced.

(Comparative Example 10)
The same procedure as in Example 10 was conducted except that the resin emulsion to be used was I, and ink for inkjet recording of Composition Example 20 shown in Table 4 was produced.

(Evaluation test 1: Evaluation of color development on plain paper)
The ink according to Examples 1 to 10 and Comparative Examples 1 to 10 was solid-printed on XeroxP paper (manufactured by Fuji Xerox Co., Ltd.) using an inkjet printer (EM-930C, manufactured by Seiko Epson Corporation) to obtain a test specimen. (Print mode is paper: plain paper, print quality: super fine, color correction: none, print direction: bidirectional). And OD (Optical Density) of each color was measured using GRETAGMACBETH SPECTROSCAN SP50 (made by Gretag) (measurement conditions were light source: D50, viewing angle: 2 degrees). The results are shown in Tables 1 and 2 as OD values.

(Evaluation test 2: Evaluation of glossiness)
The inks according to Examples 1 to 10 and Comparative Examples 1 to 10 were solid-printed on an EPSON photographic paper (manufactured by Seiko Epson Corporation) with an inkjet printer (EM-930C) to obtain a test specimen (printing mode is paper: Photo print paper, print quality: photo, color correction: none, print direction: bidirectional). The 20-degree gloss of this specimen was measured with a gloss meter (HG-268, manufactured by Suga Test Instruments Co., Ltd., V type company). The results are shown in Tables 1 and 2.

(Evaluation Test 3: Evaluation of Dispersibility)
The average particle diameter of the particles in the ink according to Examples 1 to 10 and Comparative Examples 1 to 10 was measured with a laser particle size analyzer (Zeta Sizer 3000, manufactured by Malvern). The results are shown in Tables 1 and 2.

(Evaluation Test 4: Evaluation of Storage Stability)
The initial viscosity of the pigment dispersion for ink according to Examples 1 to 10 and Comparative Examples 1 to 10 and the viscosity after standing at 70 ° C. for 1 week were measured with a rolling ball viscometer (AMVn, manufactured by Anton Paar). did. The results are shown in Tables 1 and 2 as storage stability: viscosity (mPa · s) / initial viscosity (mPa · s) after standing at 70 ° C. for 1 week.

  Tables 1 and 2 also show the monomer composition, the polymerization initiator and the pigment, and the inkjet ink composition used when the ink was produced.

In addition, the symbol shown in Table 1-Table 4 is as follows.
BZA: benzyl acrylate AA: acrylic acid MAA: methacrylic acid BPEH: t-butylperoxy (2-ethylhexanoate)
PB15: 1: C.I. I. Pigment Blue 15: 1 (trichlorophthalocyanine)
PV19: C.I. I. Pigment Violet 19 (Quinacridone)
PY74: C.I. I. Pigment Yellow 74 (Condensed Azo Pigment)
PBk7: C.I. I. Pigment Black 7 (carbon black)
1,2-HD: 1,2-hexanediol TMP: trimethylolpropane 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

As can be seen from the results described in Tables 1 to 4, when the inkjet recording inks according to Examples 1 to 10 were used, all the tests were good results, but the results of Comparative Examples 1 to 10 were used. Ink jet recording ink cannot obtain good results in any one or more of the evaluation tests.

Claims (8)

  Water, polymerized at least 50% by weight or more of benzyl acrylate and 15% by weight or less of (meth) acrylic acid as a polymer component, and having a weight average molecular weight of 20,000 to 120,000 having an acid value of 50 to 120 mgKOH / g Ink-jet recording ink comprising a pigment dispersed using a polymer, and at least 50% by weight or more of benzyl acrylate and 15% by weight or less (meth) acrylic acid are polymerized as polymer constituents. An ink comprising at least one resin fine particle comprising a polymer having an acid value of 50 to 120 mg KOH / g and a weight average molecular weight of 20,000 to 120,000 in the form of a resin emulsion.   The ink according to claim 1, wherein the polymer used in the resin emulsion is the same as the constituent component of the polymer used as the pigment dispersant in a weight conversion ratio of 50% or more.   The ink according to claim 1 or 2, wherein an average particle size of the resin fine particles contained as the resin emulsion is 30 to 150 nm.   The ink according to any one of claims 1 to 3, wherein the resin fine particles contained as the resin emulsion are contained in an amount of 0.1 to 10% by weight based on the total amount of the ink.   At least 0.05% by weight to 1% by weight of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4, The ink according to any one of claims 1 to 4, comprising at least one selected from alkylene oxide adducts of 7-diol.   The ink for inkjet recording according to any one of claims 1 to 5, comprising 1,2-alkylene glycol.   The ink for inkjet recording according to any one of claims 1 to 6, comprising one or more selected from di (tri) ethylene glycol monobutyl ether and (di) propylene glycol monobutyl ether. The ink for inkjet recording according to any one of claims 1 to 7, comprising 2-butyl-2-ethyl-1,3-propanediol.