JP2006045379A - Ink composition and inkjet recording method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition which exhibits an excellent printing quality on various kinds of recording media, particularly a high color development on ordinary paper and produces images having significantly excellent gloss on glossy paper. <P>SOLUTION: The ink composition contains a pigment, a copolymer of a vinyl polymer having a specific structure as a dispersant and a copolymerized compound of a propyleneoxy group and ethyleneoxy group having a specific chain length (hereafter called PO/EO copolymerized compound) and water as a main solvent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Background of the Invention

FIELD OF THE INVENTION The present invention relates to an ink composition for ink jet recording which has excellent print quality on various recording media, and in particular, has high color developability on plain paper and at the same time has excellent gloss on glossy paper.

BACKGROUND ART An ink jet recording method is a recording method in which printing is performed by causing ink droplets to fly and adhere to a recording medium such as paper. Due to recent advances in inkjet recording technology, the inkjet recording method has been applied to the field of high-definition printing that has been realized only by silver salt photography and offset printing. In addition, ink jet recording is also performed on glossy paper having high gloss such as photographic paper and art paper. Furthermore, in recent years, printed materials printed by inkjet printers are often used not only indoors but also outdoors for advertising and viewing purposes, and the printed materials are light resistant, gas resistant, water resistant, etc. Having excellent resistance is extremely important.

  Conventionally, an ink composition used in an ink jet recording method often uses a water-based dye as a colorant, and the water-based dye ink can be printed on various recording media, and in recording on glossy paper, Excellent gloss can be obtained. However, on the other hand, since it has the disadvantages of being inferior in light resistance, gas resistance and water resistance, recent ink development has been conducted in order to improve the disadvantages of light resistance, gas resistance and water resistance. The use of pigments has also been studied.

  An aqueous pigment ink is a dispersion in which pigment fine particles having a certain particle diameter are uniformly dispersed in an aqueous solvent, and after printing on a recording medium, an ink film containing the pigment is formed on the recording medium. Therefore, while exhibiting excellent color developability on various recording media, especially plain paper, on the other hand, when printing on a recording medium with a smooth surface such as glossy paper, light from pigment fine particles in the ink film There is a problem that the glossiness of the recorded portion is impaired due to irregular reflection.

  In response to such a problem, Japanese Patent Application Laid-Open No. 2004-75988 (Patent Document 1) enables printing with high color development and excellent glossiness by using an aqueous dispersion of water-insoluble vinyl polymer fine particles. Pigment inks have been proposed.

However, although a certain level of gloss can be obtained from the viewpoint of gloss, there is still a need for an ink composition that is further excellent in gloss.
JP 2004-75988 A

Summary of the Invention

  The present inventors have now developed a high color developability for plain paper by combining a pigment having a specific polymer fine particle as a dispersant and a copolymer of propyleneoxy group and ethyleneoxy group having a specific chain length. At the same time, it was found that an image having particularly excellent glossiness can be realized even on glossy paper. The present invention is based on this finding.

  Therefore, the present invention is an ink composition that is excellent in print quality on various recording media, and in particular, can achieve an image having particularly high gloss on plain paper as well as high color developability on plain paper. The purpose is to provide.

（式中、Ｒは、炭素数７〜１４のアルキル基を表し、ＰＯはプロピレンオキシ基を表し、ＥＯはエチレンオキシ基を表し、ｍは１〜１０の整数を表し、ｎは５〜２０の整数を表し、Ｘは１〜３の整数を表す。）
で表される化合物と、主溶媒としての水とを含んでなり、
前記ポリマーが、
Ａ）式（II）：

（式中、Ｒ^１は水素原子またはメチル基を表し、Ｒ^２は水素原子、炭素数１〜２０のアルキル基、または、炭素数１〜９のアルキルフェニル基を表し、ｏは１〜３０の整数を表す。）
で表されるモノマーＡ１、
式（III）：

（式中、Ｒ^１、Ｒ^２およびｏは式（II）で定義したものと同じ意味を表し、ｐは１〜３０の整数を表し、[ ]内のオキシエチレン基およびオキシプロピレン基はブロック付加またはランダム付加のいずれであってもよい。）で表されるモノマーＡ２、および
式（IV）：

（式中、Ｒ^１、Ｒ^２およびｏは、式（II）で定義したものと同じ意味を表す。）
で表されるモノマーＡ３から選ばれる、少なくとも一種のモノマーと、
Ｂ）塩生成基を有するモノマーと、
Ｃ）数平均分子量５００〜５００，０００のマクロモノマーと、
Ｄ）前記モノマーＡ）、Ｂ）、およびＣ）と共重合可能なモノマーとを重合させてなるビニルポリマーである。 The ink composition according to the present invention includes a pigment, a polymer that includes the pigment and that enables the pigment to be dispersed in the ink composition, and the following formula (I):

(In the formula, R represents an alkyl group having 7 to 14 carbon atoms, PO represents a propyleneoxy group, EO represents an ethyleneoxy group, m represents an integer of 1 to 10, and n represents 5 to 20) Represents an integer, and X represents an integer of 1 to 3.)
And water as a main solvent,
The polymer is
A) Formula (II):

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkylphenyl group having 1 to 9 carbon atoms, and o is 1 to 30. Represents an integer.)
Monomer A1 represented by
Formula (III):

(In the formula, R ¹ , R ² and o represent the same meaning as defined in formula (II), p represents an integer of 1 to 30, and the oxyethylene group and oxypropylene group in [] are block additions. Or any of random addition.) Monomer A2 represented by formula (IV):

(In the formula, R ¹ , R ² and o have the same meaning as defined in formula (II).)
At least one monomer selected from monomers A3 represented by:
B) a monomer having a salt-forming group;
C) a macromonomer having a number average molecular weight of 500 to 500,000;
D) A vinyl polymer obtained by polymerizing the monomers A), B), and C) with a copolymerizable monomer.

  According to the present invention, it is possible to realize an image excellent in print quality on various recording media, in particular, having high color developability on plain paper and at the same time having excellent gloss on glossy paper.

Detailed description of the invention

  The ink composition according to the present invention comprises a pigment, a vinyl polymer having a specific structure as a dispersant, a copolymer compound of propyleneoxy group and ethyleneoxy group having a specific chain length (hereinafter also referred to as PO / EO copolymer compound). And water as the main solvent.

  In the present invention, the pigment is in the form of particles as a result of being encompassed by the vinyl polymer. The particles are prepared from a pigment and a polymer described later. Although details will be described later, in brief, a pigment, a polymer dissolved or dispersed in an organic solvent, water, and a neutralizer as necessary are mixed and dispersed, the organic solvent is removed, and the desolvent is removed. Dispersed particles containing the pigment can be obtained. Hereinafter, each component constituting the ink composition will be described.

1. Pigment As the pigment contained in the ink composition of the present invention, organic pigments and inorganic pigments conventionally used in ink compositions for inkjet can be used.

  Organic pigments include azo pigments (for example, azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines). Pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), nitro pigments, nitroso pigments, aniline black, and the like.

  As the chromatic organic pigment, a yellow pigment, a cyan pigment, and a magenta pigment can be used. Examples of yellow pigments include C.I. I. Pigment Yellow 74, 93, 109, 110, 128, 138, 150, 151, 154, 155, 180, 185 and the like are preferably used, and Pigment Yellow 74 is particularly preferable.

  Examples of magenta pigments include C.I. I. Pigment red 122, 202, 209 and C.I. I. Pigment Violet 19 or the like is preferably used. I. Pigment Red 122 and Pigment Violet 19 are preferred.

  Examples of cyan pigments include C.I. I. Pigment Blue 15: 3, 15: 4 and 60 are preferably used. I. Pigment Blue 15: 3 and Pigment Blue 15: 4 are preferred.

  Further, as organic pigments used for color inks other than yellow, cyan, or magenta, C.I. I. Pigment green 7 (phthalocyanine green), 10 (green gold), 36, 37; C.I. I. Pigment brown 3, 5, 25, 26; I. Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 34, 36, 38, etc. can be used.

  Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Of these, carbon black is preferred particularly for black aqueous inks. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.

  Examples of extender pigments include silica, calcium carbonate, and talc.

2. Vinyl polymer The polymer used in the ink composition according to the present invention is a vinyl monomer obtained by polymerizing the following monomers A) to D).

(1) Monomer A)
The monomer A) means at least one monomer selected from the monomer A1 represented by the following formula (II), the monomer A2 represented by the following formula (III), and the monomer A3 represented by the formula (IV) To do.

（式中、Ｒ^１は水素原子またはメチル基を表し、Ｒ^２は水素原子、炭素数１〜２０のアルキル基または、炭素数１〜９のアルキルフェニル基を表し、ｏは１〜３０の整数を表す。）
式（III）：

（式中、Ｒ^１、Ｒ^２およびｏは式（II）で定義したものと同じ意味を表し、ｐは１〜３０の整数を表し、[ ]内のオキシエチレン基およびオキシプロピレン基はブロック付加またはランダム付加のいずれであってもよい。）
式（IV）：

（式中、Ｒ^１、Ｒ^２およびｏは、式（II）で定義したものと同じ意味を表す。） Formula (II):

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkylphenyl group having 1 to 9 carbon atoms, and o is an integer of 1 to 30. Represents.)
Formula (III):

(In the formula, R ¹ , R ² and o represent the same meaning as defined in formula (II), p represents an integer of 1 to 30, and the oxyethylene group and oxypropylene group in [] are block additions. Or any of random addition may be used.)
Formula (IV):

(In the formula, R ¹ , R ² and o have the same meaning as defined in formula (II).)

  Specific examples of the monomer A1 include polypropylene glycol mono (meth) acrylate. These can be used alone or in admixture of two or more.

  Specific examples of the monomer A2 include ethylene glycol / propylene glycol (meth) acrylate, poly (ethylene glycol / propylene glycol) mono (meth) acrylate, octoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, octoxy poly (ethylene glycol / ethylene glycol). Propylene glycol) mono (meth) acrylate, stearoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, stearoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, nonylphenoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate , Nonylphenoxypoly (ethylene glycol / propylene glycol) mono ( Data) acrylate, and the like. These can be used alone or in admixture of two or more.

  Examples of commercially available monomers A1 or A2 include Bremer PP-1000, PP-500, PP-800, AP-150, AP-400, AP-550, AP-800 manufactured by NOF Corporation. , 50PEP-300, 70PEP-350B, AEP series, 30PPT-800, 50PPT-800, 70PPT-800, APT series, 10PPB-500B, 10APB-500B, 50POEP-800B, 50AOEP-800B, ASEP series, PNEP series, PNPE Series, 43ANEP-500, 70ANEP-550 and the like.

  Specific examples of the monomer A3 include polyethylene glycol mono (meth) acrylate.

  Specific examples of commercially available monomer A include NK ester M-20G, 40G, 90G, 230G manufactured by Shin-Nakamura Kagaku Co., Ltd., Blemmer PE series of Nippon Oil & Fats Co., Ltd., PME-100, 200, 400 1000 etc. are mentioned.

  The content of the (meth) acrylic acid ester monomer (monomer A) in the vinyl polymer is preferably 5 to 45% by weight, and more preferably 5 to 35% by weight, from the viewpoint of printing density and ink viscosity.

(2) Monomer B)
Monomer B) is a monomer comprising a salt-forming group.

  The salt-forming group-containing monomer is preferably an anionic monomer or a cationic monomer. Anionic monomers and cationic monomers can be used alone or in admixture of two or more.

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

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

  As the anionic monomer, an unsaturated carboxylic acid monomer is preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoint of ink viscosity and dischargeability.

Examples of the cationic monomer include polyvinylamine, polyallylamine, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropylacrylamide and the like. Of these, N, N-dimethylaminoethyl acrylate and N, N-dimethylaminopropylacrylamide are particularly preferred. The content of the salt-forming group-containing monomer B) is 3 to 3 from the viewpoints of dispersion stability and ejection stability. It is 40% by weight, preferably 5 to 30% by weight.

(3) Monomer C)
Monomer C) is a polystyrene macromonomer having a number average molecular weight of 500 to 500,000.

  Preferable examples of the macromonomer include macromers having a polymerizable functional group at one end and preferably having a number average molecular weight of 500 to 500,000, more preferably 1,000 to 10,000.

  Specific examples of the macromonomer include a styrene macromer having a polymerizable functional group at one end, and a styrene / acrylonitrile macromer having a polymerizable functional group at one end. Among these, since a vinyl polymer can be sufficiently contained with a colorant, a styrenic macromer having a polymerizable functional group at one end is preferable.

  Acrylonitrile is mentioned as a monomer other than styrene constituting the styrenic macromonomer having a polymerizable functional group at one end. Further, the content of styrene is preferably 60% by weight or more, more preferably 70% by weight or more, from the viewpoint that the pigment is sufficiently contained in the vinyl polymer.

  Among the styrenic macromers having a polymerizable functional group at one end, those having an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group at one end are preferable.

  Examples of commercially available styrenic macromers include AS-6, AN-6, AN-6S, HS-6S, and HS-6 manufactured by Toa Gosei Co., Ltd.

  The content of the macromonomer C) is preferably 0.1 to 40% by weight, more preferably 1 to 30% by weight, from the viewpoint of water resistance and scratch resistance.

(4) Monomer D)
Monomer D) is copolymerizable with monomers A), B), and C), and specific examples thereof include (meth) acrylic acid esters, aromatic ring-containing monomers, and macromers. These can be used alone or in admixture of two or more. This monomer D) preferably contains at least one selected from the group consisting of aromatic ring-containing monomers and macromers from the viewpoint of water resistance and scratch resistance.

  Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) butyl (meth) acrylate, (iso) amyl (meta) ) Acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, (Meth) acrylic acid esters in which the ester moiety such as (iso) stearyl (meth) acrylate is an alkyl group having 1 to 18 carbon atoms are used, and these may be used alone or in combination of two or more. Can do.

  The terms “(iso or tertiary)” and “(iso)” mean both the case where these groups are present and the case where these groups are not present. Indicates.

  From the viewpoint of water resistance, the aromatic ring-containing monomer includes styrene, vinyl naphthalene, α-methylstyrene, vinyl toluene, ethyl vinyl benzene, 4-vinyl biphenyl, 1,1-diphenyl ethylene, benzyl (meth) acrylate, phenoxyethyl ( 1 selected from the group consisting of (meth) acrylate, 2-hydroxy-3phenoxypropyl acrylate, 2-methacryloyloxyethyl-2hydroxypropyl phthalate, 2-acryloyloxyethyl phthalate and neopentyl glycol acrylate benzoate More than species are preferred. Among these, at least one selected from the group consisting of styrene, α-methylstyrene, vinyl toluene, and vinyl naphthalene is more preferable from the viewpoint of water resistance and scratch resistance.

  In the vinyl monomer obtained by polymerizing the above monomers A), B), C), and D), the monomer A) is present in an amount of 5 to 45% by weight (preferably 5 to 35% by weight), Monomer B) is 3 to 40 wt% (preferably 5 to 30 wt%), Monomer C) is 0.1 to 40 wt% (preferably 10 to 30 wt%), and Monomer D) is 0 to 87 wt% ( Preferably, it is 0 to 75% by weight.

  The weight average molecular weight of the vinyl polymer is preferably 3,000 to 300,000, more preferably 5,000 to 200,000, from the viewpoints of print density and ejection stability.

  The pigment dispersion using the vinyl polymer as a dispersant can be prepared, for example, by the method described in JP-A No. 2001-247810. Specifically, a polymer solution dissolved in a water-soluble organic solvent, a pigment, and, if necessary, a neutralizing agent are mixed to prepare a solvent dispersion, and the dispersion is developed into an aqueous phase to develop an aqueous suspension. Prepare a suspension. And the water-soluble organic solvent added at the time of solvent dispersion liquid adjustment is distilled off, and a pigment is included with a vinyl polymer particle.

  The neutralizing agent may be appropriately determined. Examples of the alkali include tertiary amines such as trimethylamine and triethylamine, ammonia, sodium hydroxide, potassium hydroxide and the like. As the acid, inorganic bases such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid, propionic acid, lactic acid, succinic acid, glycolic acid, gluconic acid, and glyceric acid can be used.

  As the organic solvent, water-soluble organic solvents are preferable, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone, diethyl ketone and methyl isobutyl ketone, ethers such as dibutyl ether, tetrahydrofuran and dioxane, and the like. It is done.

  Dispersers can be used for the process of including the pigment in the polymer. Dispersers such as ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc. To do. More preferably, a high-pressure homogenizer that is less likely to be mixed with crushed pieces of the dispersion medium is used.

  The particle size of the vinyl polymer particles thus obtained is preferably about 25 to 250 nm, more preferably the lower limit is about 30 nm and the upper limit is about 175 nm.

（式中、Ｒは、炭素数７〜１４のアルキル基を表し、ＰＯはプロピレンオキシ基を表し、ＥＯはエチレンオキシ基を表し、ｍは１〜１０の整数を表し、ｎは５〜２０の整数を表し、Ｘは１〜３の整数を表す。） 3. PO / EO Copolymer Compound The PO / EO copolymer compound used in the ink composition according to the present invention is represented by the following formula (I).

(In the formula, R represents an alkyl group having 7 to 14 carbon atoms, PO represents a propyleneoxy group, EO represents an ethyleneoxy group, m represents an integer of 1 to 10, and n represents 5 to 20) Represents an integer, and X represents an integer of 1 to 3.)

In the above formula (I), EO represents ethyleneoxy, that is, —CH ₂ CH ₂ O—, and PO represents propyleneoxy, that is, —CH ₂ CH ₂ CH ₂ O— or —CH (CH ₃ ) CH ₂ O—. . The EO and PO are structures in which PO is first added to the alcohol group and then EO is added in the molecule of the compound represented by formula (I) (that is, in [] in the above formula (I)). Are preferred.

  The PO / EO copolymer compound has an alkyl chain length of 7 to 14 carbon atoms. By using a combination of a PO / EO copolymer compound having an alkyl chain in this range and the above-described pigment dispersion, an image having a print portion with excellent glossiness even when glossy paper is used as a recording medium. Is obtained. The alkyl chain may be branched or linear, and the number of carbon atoms is more preferably 9-14.

  Moreover, it is preferable that n and m in the compound of the above formula (I) satisfy n / m ≧ 1.5. By setting the ratio of n / m, that is, the ethyleneoxy group to the propyleneoxy group to be 1.5 or more, an image having further excellent gloss can be realized.

  From the viewpoint of viscosity suitability of the ink composition part, the number average molecular weight of the compound of the above formula (I) is preferably 2,000 or less. In addition, a number average molecular weight is a styrene conversion molecular weight when the solvent is measured as THF using gel permeation chromatography (GPC) of L7100 system made by Hitachi, Ltd.

  The content of the PO / EO copolymer compound represented by the above formula (I) is preferably 0.5 to 5.0% by weight based on the total amount of the ink composition. If it is 0.5% by weight or more, an image having excellent gloss can be realized, and if it is 5.0% by weight or less, the viscosity of the ink composition can be easily adjusted.

  The compound of the above formula (I) can be obtained by adding a target molar amount of ethylene oxide or propylene oxide in an alkali atmosphere or the like using an alcohol having a corresponding structure or a polyhydric alcohol as a starting material. The compound of the formula (I) thus obtained is generally a mixture of two or more compounds represented by the formula (I).

  Moreover, what is marketed can also be used conveniently. Specific examples include FINESURF 560, 580, 5010, 9010, 7045, 7085, BLAUNON DAP-1008, ELP-0809B, ELP-1608B, etc. manufactured by Aoki Oil & Fat Co., Ltd.

4). Water and other components In the present invention, the chromatic ink composition contains water as a main solvent. As the water, pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water can be used. In addition, the use of water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold or bacteria can be prevented when the ink composition is stored for a long period of time.

  The ink composition according to the present invention preferably further comprises a pH adjuster. Specific examples of pH adjusters include hydroxides of alkali metals such as lithium hydroxide, potassium hydroxide and sodium hydroxide, amines such as ammonia, triethanolamine, tripropanolamine, diethanolamine and monoethanolamine. More preferred are those selected from the group consisting of triethanolamine, tripropanolamine, and mixtures thereof.

  In the present invention, the pH of the ink composition is preferably 8.0 to 11. By adjusting the pH of the ink composition in such a range, a more excellent gloss feeling can be realized. In order to bring the ink composition to a pH in the above range, it can be suitably adjusted by using the above pH adjuster.

  In addition, the ink composition according to the present invention is compatible with water, and the pigment, the polymer, the compound of the formula (I), and the pH adjuster and various components described later are included in the ink composition. It is preferable to contain a water-soluble organic solvent that can be stably dissolved or dispersed.

  Preferred examples of the water-soluble organic solvent include improved solubility of glycol ethers having low solubility in water and other components, further improved permeability to a recording medium (for example, paper), and nozzle clogging. As a function that can be expected to prevent water, alkyl alcohols having 1 to 4 carbon atoms such as ethanol, methanol, butanol, propanol, isopropanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl Ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, die Lenglycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1- Methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, Dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether , Glycol ethers such as dipropylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, formamide, acetamide, dimethyl sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin , Sulfolane, and mixtures thereof.

  In addition, glycols can be added as water-soluble organic solvents to the ink composition according to the present invention in order to suppress drying of the ink in front of the nozzles of the recording head. Examples thereof include ethylene glycol, diethylene glycol, and triethylene. Glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol having a molecular weight of 2000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1, 5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, glycerin, mesoerythritol, pentaerythritol and the like can be mentioned.

  Furthermore, saccharides can be used for the same purpose. Examples include monosaccharides and polysaccharides, in addition to glucose, mannose, fructose, ribose, xylose, arabinose, lactose, galactose, aldonic acid, glucitol, maltose, cellobiose, sucrose, trehalose, maltotriose, etc. Alginic acid and its salts, cyclodextrins, and celluloses can be used. The amount added may be appropriately determined, but is preferably 0.05% by weight or more and 30% by weight or less. By being in the above range, even when the ink composition is dried at the tip of the head, the clogging can be easily recovered, and the viscosity of the ink composition capable of stable printing can be easily realized. Can do. According to a preferred embodiment of the present invention, more preferable addition amount of glucose, mannose, fructose, ribose, xylose, arabinose, lactose, galactose, aldonic acid, glucitolose, maltose, cellobiose, sucrose, trehalose, maltotriose is 3-20. % By weight. In addition, since addition of alginic acid, its salt, and cellulose tends to increase the viscosity of the ink composition, attention must be paid to the addition amount.

  Further, the ink composition according to the present invention preferably contains a surfactant in order to control its permeability or to improve the water solubility of the compound represented by the formula (I). The surfactant to be added is preferably compatible with other components in the ink composition. Further, a surfactant having high penetrability and stability is preferable. As the surfactant, amphoteric surfactants and nonionic surfactants are preferably used.

  Preferred examples of amphoteric surfactants include lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine and others Examples include imidazoline derivatives.

  Preferred examples of nonionic surfactants include acetylene glycol surfactants, acetylene alcohol surfactants, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl. Ethers such as allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene oleic acid ester, polyoxyethylene distearic acid ester , Sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxye Examples include ester surfactants such as lenmonooleate and polyoxyethylene stearate, silicon surfactants such as dimethylpolysiloxane, fluorine-containing surfactants such as other fluorine alkyl esters and perfluoroalkyl carboxylates, and the like. In particular, acetylene glycol surfactants and acetylene alcohol surfactants are preferred. When these surfactants are added to the ink composition, they are preferable because they have a low foaming property and an excellent antifoaming function. Specific examples of acetylene glycol surfactants and acetylene alcohol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne- 3,6-diol, 3,5-dimethyl-1-hexyne-3ol, etc. are available, but are also commercially available. For example, Surfynol 104, 82, 465, 485, TG of Air Products, etc. Examples include Olfin STG and Olphine E1010 manufactured by Nissin Chemical.

  The addition amount of the surfactant is preferably 0.01% by weight or more and 3% by weight or less with respect to the total amount of the ink composition, the more preferable upper limit value is 2.0% by weight, and the preferable lower limit value is 0.05% by weight.

  The ink composition according to the present invention may be added with a pH buffer, an antioxidant, an ultraviolet absorber, an antiseptic or antifungal agent, a chelating agent, and the like, if necessary.

  Specific examples of the pH buffering agent include collidine, imidazole, phosphoric acid, 3- (N-morpholino) propanesulfonic acid, tris (hydroxymethyl) aminomethane, boric acid and the like.

  Specific examples of the antioxidant or ultraviolet absorber include allophanates such as allophanate and methyl allophanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret, L-ascorbic acid and its salts, etc., manufactured by Ciba Geigy Examples include Tinuvin 328, 900, 1130, 384, 292, 123, 144, 622, 770, 292, Irgacor 252, 153, Irganox 1010, 1076, 1035, MD1024, or lanthanide oxides.

  Specific examples of preservatives or fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazoline-3- ON (Avecia's Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN) and the like. Specific examples of the chelating agent include ethylenediaminetetraacetic acid (EDTA).

5. Preparation of Ink Composition The ink composition according to the present invention may be prepared by supplying the above-described components to a dispersing / mixing machine (for example, a ball mill, a sand mill, an attritor, a basket mill, a roll mill, etc.) and dispersing them. . According to a preferred embodiment of the present invention, it is preferable to filter the ink stock solution obtained by the above-described dispersing / mixing device using a filter such as a membrane filter or a mesh filter to remove coarse particles.

6). Inkjet recording method and apparatus An inkjet recording method in which the ink composition according to the present invention is used discharges ink composition droplets and attaches the droplets to a heated recording medium for printing. As an example of a method for ejecting ink composition droplets, for example, an electrostrictive element is used to convert an electrical signal into a mechanical signal, and ink stored in the nozzle head portion is intermittently ejected onto the surface of the recording medium. A method of recording characters and symbols, ink heated in the nozzle head portion is heated rapidly at a location very close to the discharge portion, bubbles are generated, and the ink is intermittently discharged by the volume expansion caused by the bubbles, and characters are printed on the surface of the recording medium. And a method of recording symbols. According to a preferred embodiment of the present invention, the ink composition according to the present invention is preferably used in an ink jet recording method using an electrostrictive element. The ejection of the ink composition droplets is preferably performed by a recording head that ejects ink droplets using the mechanical action of the piezoelectric element.

  Further, according to the present invention, a recorded matter recorded by the recording method is also provided.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

1. Preparation of vinyl polymer A monomer having the following composition was prepared.

Polypropylene glycol monomethacrylate (n = 9) 15% by weight
(A compound in which R ₁ is methyl and R ₂ is hydrogen in the formula (II). Trade name: Blemmer PP-500, manufactured by NOF)
Polyethylene glycol monomethacrylate (n = 23) 10% by weight
(In formula (III), m = 23, a compound in which R ₁ and R ₂ are methyl. Trade name: NK ESTER M230G, manufactured by Shin-Nakamura Chemical Co., Ltd.)
Methacrylic acid 14% by weight
Styrene monomer 36% by weight
15% by weight of styrene macromer
(Styrene-acrylonitrile copolymer macromer, styrene content: 75% by weight, number average molecular weight: 6,000, polymerizable functional group: methacryloyl group, trade name: AN-6, manufactured by TOAGOSEI)
n-butyl methacrylate 10% by weight
A reaction vessel was charged with 20 parts by weight of methyl ethyl ketone, 0.03 part by weight of a polymerization chain transfer agent (2-mercaptan etarule), and 10% of the total amount of the above monomers, and mixed. Thereafter, the container was replaced with nitrogen gas. Meanwhile, the dropping device was filled with the remaining 90% of the monomer composition.

  Polymer chain transfer agent (2-mercaptan ethanol) 0.27 wt%, methyl ethyl ketone 60 wt%, and 2,2'-azobis (2,4-dimethylvaleronitrile) were then added to the dropping apparatus and mixed. Thereafter, the dropping device was replaced with nitrogen gas.

  The temperature of the mixture in the reaction vessel was raised to 65 ° C. with stirring in a nitrogen atmosphere, and the mixture in the dropping apparatus was dropped into the reaction vessel over 3 hours. Two hours after the completion of dropping at 65 ° C., a solution in which 0.3% by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 5% by weight of methyl ethyl ketone was added. The mixture was aged at 65 ° C. for 2 hours and further at 70 ° C. for 2 hours to obtain a polymer solution.

  A portion of the polymer solution obtained as described above was isolated by drying under reduced pressure by removing the solvent.

  The weight average molecular weight was determined by gel permeation chromatography using polystyrene as a standard substance and phosphoric acid having a concentration of 60 mmol / L and dimethylformamide containing 50 mmol / L of lithium bromide as a solvent. As a result, the weight average molecular weight was 70,000.

2. Preparation of Pigment Dispersion Dissolve 5 parts by weight of the vinyl polymer obtained above in 45 parts by weight of methyl ethyl ketone, add a predetermined amount of a neutralizing agent (20% aqueous sodium hydroxide solution) to form a salt-forming group. Neutralized, and as a pigment, I. 20 parts by weight of Pigment Violet 19 was added and kneaded in a bead mill for 2 hours.

  After 120 parts by weight of ion-exchanged water was added to the kneaded product obtained above and stirred, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, and a part of the water was further removed, so that the solid content concentration was 20%. A weight percent pigment dispersion was obtained.

を用いた（比較例３および４）。

3. Preparation of PO / EO Copolymer Compound FINESURF (manufactured by Aoki Oil & Fats Co., Ltd.) was used as the PO / EO copolymer compound represented by the formula (I). Table 1 below shows the alkyl chain length, EO / PO molar ratio, and molecular weight for each FINESURF used as an example. In addition, as a comparative example, a PO / EO copolymer compound represented by the following formula (V) in which R represented by the above formula (I) is C4, m is 6, and n is 4

(Comparative Examples 3 and 4).

4). Preparation of Ink Composition According to the composition shown in Table 2 below, the above-mentioned pigment dispersion, PO / EO copolymer compound, solvents and ultrapure water were mixed and stirred for 2 hours. Subsequently, the mixture was filtered using a membrane filter (trade name) (manufactured by Nippon Millipore Limited) having a pore diameter of about 8 μm to prepare a color ink. In Table 2, the amount of each composition added is% by weight. Further, the pH value of each ink composition was measured. The measurement results of pH were as shown in Table 2.

5. Evaluation of Ink Composition The following tests were performed on the ink compositions of Examples 1 to 8 and Comparative Examples 1 to 4. The results are shown in Table 3.

Evaluation 1: Glossiness test Glossiness was evaluated by printing on 1440 × 720 dpi on PM photo paper manufactured by Seiko Epson Corporation using an ink jet printer PX-G900 manufactured by Seiko Epson Corporation and leaving it at 25 ° C. for 24 hours. Then, the specular glossiness of the recording surface at an incident angle of 20 degrees was measured by using a gloss meter GM-268 manufactured by Konica Minolta Sensing Co., Ltd. A value obtained by taking an average of 5 times for each recording paper was calculated and evaluated based on the following criteria.

A: Specular gloss is 60 or more B: Specular gloss is 55 or more and less than 60 C: Specular gloss is 50 or more and less than 55 D: Specular gloss is less than 50 Evaluation 2: Print density test Using the printer, Solid printing was performed on Xerox 4024 at 720 × 720 dpi, and after leaving for 24 hours at 25 ° C., the print density on the recording surface was measured using a Spectrolino manufactured by Gretag. A value obtained by taking an average of 5 times for each recording paper was calculated and evaluated based on the following criteria.

A: Print density is 1.1 or more B: Print density is 1.0 or more and less than 1.1 C: Print density is 0.9 or more and less than 1.0

Claims (11)

A pigment, a polymer including the pigment and capable of dispersing the pigment in the ink composition, and a compound represented by the following formula (I):

(In the formula, R represents an alkyl group having 7 to 14 carbon atoms, PO represents a propyleneoxy group, EO represents an ethyleneoxy group, m represents an integer of 1 to 10, and n represents 5 to 20) Represents an integer, X
Represents an integer of 1 to 3. )
And water as a main solvent,
The polymer is
A) Formula (II):

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkylphenyl group having 1 to 9 carbon atoms, and o is 1 to 30. Represents an integer.)
Monomer A1 represented by
Formula (III):

(Wherein R ¹ , R ² and o represent the same meaning as defined in formula (II), p represents an integer of 1 to 30, and the oxyethylene group and oxypropylene group in [] are block additions. Or any of random addition.) Monomer A2 represented by formula (IV):

(In the formula, R ¹ , R ² and o have the same meaning as defined in formula (II).)
At least one monomer selected from monomers A3 represented by:
B) a monomer having a salt-forming group;
C) a macromonomer having a number average molecular weight of 500 to 500,000;
D) An ink composition, which is a vinyl polymer obtained by polymerizing the monomers A), B), and C) with a copolymerizable monomer. The vinyl polymer is
5 to 45% by weight of monomer A)
3-40% by weight of said monomer B),
0.1 to 40% by weight of the monomer C),
The ink composition according to claim 1, wherein the monomer D) is polymerized with 0 to 87% by weight.   The ink composition according to claim 1, wherein n and m in the compound of the formula (I) satisfy n / m ≧ 1.5.   The ink composition according to claim 1, wherein the compound of the formula (I) has a number average molecular weight of 2000 or less.   The ink composition according to any one of claims 1 to 4, wherein the compound of formula (I) is contained in an amount of 0.5 to 5.0% by weight based on the total amount of the ink composition.   The ink composition according to any one of claims 1 to 5, wherein the pH is in the range of 8.0 to 11.0.   The ink composition according to any one of claims 1 to 6, further comprising a pH adjusting agent selected from the group consisting of alkali metal hydroxides, triethanolamine, tripropanolamine, and mixtures thereof. object.   The ink composition according to any one of claims 1 to 7, further comprising a water-soluble organic solvent and / or a surfactant. The water-soluble organic solvent is selected from the group consisting of polyhydric alcohols, glycol-based butyl ethers, pyrrolidones, and mixtures thereof;
The ink composition according to claim 8, wherein the surfactant is an acetylene glycol surfactant.   An ink jet recording method for performing printing by discharging droplets of an ink composition and attaching the droplets to a recording medium, wherein the ink composition according to any one of claims 1 to 9 is used. An ink jet recording method using   A recorded matter recorded by the ink jet recording method according to claim 10.