JP2006143883A - Coloring agent and ink composition for inkjet recording using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coloring agent having an excellent dispersion stability even when an ink composition is made to a high concentration while it has an equal performance to a pigment-based coloring material. <P>SOLUTION: The coloring agent comprises a polymer containing a monomer unit having a structure that a pigment compound and polyoxy ethers having an ethylenic unsaturated group are chemically bonded through a sulfonic acid group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Background of the Invention

FIELD OF THE INVENTION The present invention relates to a colorant that can provide an ink composition having excellent light material dispersibility, ejection stability and water resistance while having light resistance equivalent to that of a pigment-based color material.

BACKGROUND ART An ink jet recording method is a recording method in which ink droplets are ejected from fine nozzles and attached to a recording medium for recording. Conventionally, water-soluble dyes have been used as coloring materials in inks used in the ink jet recording method, and these water-soluble dye-based inks are required to have improved light resistance and water resistance.

  On the other hand, in order to improve the water resistance and light resistance of recorded images, inks using pigments as color materials have been developed. Usually, since the pigment is insoluble in water, a resin for dispersing the pigment in the ink is used together for the purpose of improving the ejection stability of the ink. In the pigment ink, since it is difficult to achieve both the dispersion stability of the pigment as the color material in the ink and the ejection stability of the inkjet recording, for example, the pigment dispersion made of a resin having an oxyethylene chain. An agent is used to improve the dispersion stability of the pigment (Japanese Patent Laid-Open No. 10-46079 (Patent Document 1) and the like). However, since the above-described pigment dispersion resin has a polyoxyethylene chain having extremely high water solubility, it is considered that the pigment cannot be efficiently adsorbed to the resin and the water resistance of the printed matter is insufficient.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 2003-327862 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2004-26662 (Patent Document 3) disclose a pigment at the same time when a monomer having an oxyethylene chain is polymerized. An ink composition having both water resistance and pigment dispersion stability has been proposed by adding colored polymer particles to produce colored fine particles.

  However, the pigment itself has very low reactivity with the oxyethylene chain, and the pigment and the resin are not chemically bonded. Therefore, it is presumed that in the obtained colored fine particles, the pigment and the resin are bonded only by physical adsorption affinity and maintained in a dispersed state in the ink. Such colored fine particles can be stably dispersed in the ink when having a certain particle size, but when the particle size becomes submicron order, the adsorptive power between the pigment and the resin is weakened, and the colored fine particles are stable. It is considered that it cannot exist in the ink.

Here, in order to increase the pigment concentration while maintaining the ejection stability, it is necessary to make the particle diameter of the colored fine particles smaller, so there is a concern about the dispersion stability of the pigment in the colored fine particles.
Japanese Patent Laid-Open No. 10-46079 JP 2003-327862 A JP 20042662 A

Summary of the Invention

  The present inventors have now found that even when a dye is chemically bonded to a specific monomer having an oxyethylene chain, the coloring or color tone of the dye does not change, and a colored resin comprising such a monomer is used as a colorant. It has been found that, by using it, a colorant having excellent dispersion stability can be obtained even when the ink composition has a high concentration while having performance equivalent to that of a pigment-based color material. The present invention is based on this finding.

  Accordingly, an object of the present invention is to provide a colorant having excellent dispersion stability even when the ink composition has a high concentration while having performance equivalent to that of a pigment-based color material.

  The colorant according to the present invention comprises a polymer comprising a monomer unit having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via a sulfonic acid group. Is.

Moreover, the method for producing the colorant as another aspect of the present invention includes a step of finely dispersing a nonionic polymerization initiator in an aqueous medium containing a dispersion stabilizer,
A monomer having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via a sulfonic acid group in an aqueous medium in which the polymerization initiator is finely dispersed, and the ethylenically unsaturated Adding a monomer having a bond to prepare a polymerization solution;
Heating and polymerizing the polymerization solution while stirring so that the monomer is not suspended;
Is included.

  By using such a colorant in the ink composition, the colorant has excellent dispersion stability even when the ink composition has a high concentration while having performance equivalent to that of a pigment-based color material. Can be realized.

Detailed description of the invention

Colorant The colorant according to the present invention comprises a polymer comprising a monomer unit having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via a sulfonic acid group. Is. Conventionally, a resin having an oxyethylene chain has been used as a pigment dispersant in order to stably disperse the pigment in the ink. However, with a pigment having a particle size on the order of several tens of nanometers, the dispersion stability decreases. End up. In the present invention, colorant particles on the order of several tens of nanometers are realized by chemically bonding a dye compound to a resin having an oxyethylene chain. That is, since the colorant according to the present invention has a structure in which the dye compound is chemically bonded to the resin, even when the colorant is finely divided, the colorants hardly aggregate. Therefore, by using such a fine particle colorant, the colorant concentration in the ink can be increased, and even when a high-concentration ink composition is obtained, the dispersibility of the colorant is excellent. Excellent discharge stability and water resistance can be realized.

  In addition, even when the dye compound is chemically introduced into the polymer chain in this way, since the dye compound and the oxyethylene chain are covalently bonded via a sulfonic acid group, the original color developability of the dye compound Will not be affected. The reason for this is not clear, but is considered to be due to bonding with the polyoxyethylene chain in a state where the conjugation of the dye compound (chromophore) is maintained. Furthermore, even when a normal dye is used as the coloring compound, the colorant has the form of fine particles, and thus has light resistance equivalent to that of a pigment.

（式中、Ｒ_１は水素またはメチル基を表し、Ｒ_２は色素化合物を表し、ｍは１〜４の整数を表し、ｎは１〜２０の整数を表す。）
で表されるものであることが好ましい。このモノマー単位は、色素化合物（Ｒ_２）が、スルホン酸基を介してオキシエチレン鎖と化学的に結合した構造を有している。本発明においては、オキシエチレン鎖の鎖長は、ｎが６〜１３であることが好ましい。この範囲とすることにより、着色剤の最大粒子径を２μｍ以下とすることができる。 The monomer unit has the following formula (I):

(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a dye compound, m represents an integer of 1 to 4, and n represents an integer of 1 to 20)
It is preferable that it is represented by these. This monomer unit has a structure in which a dye compound (R ₂ ) is chemically bonded to an oxyethylene chain via a sulfonic acid group. In the present invention, n is preferably 6 to 13 in the chain length of the oxyethylene chain. By setting it as this range, the maximum particle diameter of the colorant can be 2 μm or less.

  As polyoxyethers having an ethylenically unsaturated group, the polyoxyether portion is preferably polyoxyethylene. An ether-type nonionic surfactant compound can also be used as the polyoxyether portion. As the ether-type nonionic surfactant compound in this case, polyoxyethylene alkyl ether, alkyl glyceryl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene ether, polyoxyalkylene alkyl ether, etc. are preferably used. it can. Moreover, as an ethylenically unsaturated group, although acrylic acid, methacrylic acid, etc. can be used conveniently, it is not limited to these.

As the dye compound (R ₂ ) constituting the monomer unit represented by the above formula (I), a compound having a phthalocyanine skeleton, an azo skeleton, an anthraquinone skeleton, a dioxazine skeleton, a benzimidazolone skeleton, a molybdate skeleton, or a pyrazolone skeleton is preferable. Can be used for As described above, the colorant according to the present invention is obtained by reacting R ₂ which is a dye compound with a polyoxyether having an ethylenically unsaturated group via a sulfonic acid group. It is preferable that the hue of the dye compound itself does not change due to such chemical bonding. From such a viewpoint, it is more preferable to use a compound having a phthalocyanine skeleton as R ₂ . Further, in the present invention, it has been found that when the phthalocyanine skeleton is used as the coloring compound, the bronze phenomenon that has occurred in the conventional ink composition containing a cyan colorant is remarkably improved.

  In addition to the monomer unit represented by the above formula (I), the polymer constituting the colorant further includes a monomer unit having an ethylenically unsaturated bond and not having the dye compound. It is preferable that it consists of. By using such a copolymer, the fixability of the colorant to the low recording medium is further improved.

  The monomer having such an ethylenically unsaturated bond is not particularly limited, and examples thereof include 1,3-butadiene, 1,2-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 2,3-pentadiene. , Isoprene, 1,2-hexadiene, 1,3-hexadiene, 1,4-hexanediene, 1,5-hexazine, 2,3-hexadiene, 2,4-hexadiene, 2,3-dimethyl-1,3-butadiene , 2-ethyl-1,3-butadiene, 1,2-heptadiene, 13, -heptadiene, 1,4-heptadiene, 1,5-heptadiene, 1,6-heptadiene, 2,3-heptadiene, 2,5- Heptadiene, 3,4-heptadiene, 3,5-heptadiene, cyclopentadiene, dicyclopentadiene, ethylidene norbornene, etc. Aromatic monomers such as diene monomers, styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, vinylnaphthalene, divinylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic N-propyl acid, i-propyl (meth) acrylate, n-butyl (meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, hexyl (meth) acrylate, (meth ) -2-ethylhexyl acrylate, octyl (meth) acrylate, i-nonyl (meth) acrylate, decyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxylethyl (meth) acrylate, ) Acrylic acid alkyl ester, itaconic acid, fumaric acid, (meth) acrylic acid, maleic acid Unsaturated carboxylic acids such as crotonic acid, ethyl methacrylate unsaturated carboxylic acids such as (meth) acrylamide and N-methylol acrylamide, vinyl esters such as vinyl acetate and vinyl propionate, anhydrous ethylenically unsaturated dicarboxylic acids Products, monoalkyl esters, monoamides, aminoalkyl esters of ethylenically unsaturated carboxylic acids such as aminoethyl acrylate, dimethylaminoethyl acrylate, butylaminoethyl acrylate, aminoethylacrylamide, dimethylaminomethylmethacrylamide, methylaminopropylmethacrylamino Ethylenically unsaturated carboxylic acid aminoalkylamides, vinyl cyanide compounds such as (meth) acrylonitrile, α-chloroacrylonitrile, glycidyl Meth) available unsaturated aliphatic glycidyl esters such as acrylates, these monomers may be used singly or may be used in combination of two or more. Among the above monomers, styrene and (meth) acrylic acid are preferable.

  The polymer constituting the colorant may contain a monomer unit having an ethylenically unsaturated bond as described above, but preferably contains 30 to 100 mol% of the monomer unit represented by the formula (I). By setting it as such a range, the coloring agent which has a particle diameter of several tens nanometer order can be obtained suitably.

Method for Producing Colorant A method for producing a colorant as a first embodiment according to the present invention comprises a step of finely dispersing a nonionic polymerization initiator in an aqueous medium containing a dispersion stabilizer. A monomer having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded to each other via a sulfonic acid group in a finely dispersed aqueous medium, and a monomer having an ethylenically unsaturated bond The polymerization solution is prepared by addition, and this polymerization solution is heated and polymerized in an inert atmosphere while stirring so that the monomer is not suspended, thereby obtaining a colorant. By stirring so that the monomer is not suspended in the aqueous medium in which the polymerization initiator is finely dispersed, particles having a particle diameter of 2 μm or less can be obtained. In the present invention, the monomer represented by the above formula (I) is used as a monomer having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via a sulfonic acid group. It can be preferably used.

  In addition, the method for producing a colorant according to the second aspect of the present invention includes a polyoxyether having a dye compound and an ethylenically unsaturated group via a sulfonic acid group in an aqueous medium containing a dispersion stabilizer. The monomer and the nonionic polymerization initiator having a chemically bonded structure are finely dispersed, and a monomer having an ethylenically unsaturated bond is added to the finely dispersed aqueous medium to prepare a polymerization solution. The polymerization solution is heated and polymerized in an inert atmosphere while stirring so that the monomer is not suspended, thereby obtaining a colorant. In the present invention, the monomer represented by the above formula (I) is used as a monomer having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via a sulfonic acid group. It can be preferably used. Thus, by stirring so that the monomer is not suspended in the aqueous medium in which the monomer represented by the above formula (I) and the polymerization initiator are finely dispersed, coarse particles having a particle diameter of 1 μm or more can be suppressed. it can.

  The monomer can be dispersed in an aqueous medium by using glycols, an emulsifier, or the like, but a dispersion stabilizer is used to stably disperse the monomer. As the dispersion stabilizer, a substance having a wetting action of 100 or more in molecular weight having an acid value such as Disper BYK-190 commercially available from Big Chemie Japan, Inc. can be suitably used.

Ink Composition The ink composition according to the present invention contains the above colorant as a coloring material. By using the colorant according to the present invention, it is possible to adjust a higher concentration of ink than when a normal dye is used as a coloring material. Even when the concentration is high, nozzle clogging does not occur. Furthermore, even when the particle size of the coloring material (coloring agent) is reduced to the order of several tens of nanometers, the dispersibility of the coloring material is stably maintained, so that the viscosity is lower than that of a normal pigment-based ink. Become.

  The ink composition according to the present invention is used as a coloring material with the above-described colorant, and may contain additives used in a normal ink composition in addition to the above-described components.

  As preferred additives in the ink composition of the present invention, wetting agents, surfactants, penetrants and the like can be used.

  As the wetting agent, an alcohol compound having an alkyl group having 5 to 10 carbon atoms, an ether-modified organosiloxane compound, or the like can be preferably used.

  Examples of the alcohol compound include 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2,6-hexanetriol, ethylene glycol monohexyl ether, diethylene glycol mono Examples include hexyl ether, triethylene glycol monohexyl ether, pentanol, hexanol, heptanol, octanol and the like. The alkyl group of these compounds may be linear or branched. Preferred are 1,2-hexanediol and diethylene glycol monohexyl ether. These alcohol compounds may be used alone or in combination of two or more. Those skilled in the art can understand that these wetting agents also function as penetrants.

  As the polyether-modified organosiloxane compound, for example, a silicon surfactant BYK-345, BYK-346, BYK-347, or BYK-348 commercially available from Big Chemie Japan, Inc. can be preferably used.

  The addition amount of the wetting agent may be appropriately determined, but is preferably about 0.1 to 30% by weight, more preferably about 3 to 20% by weight.

  The ink composition according to the present invention may further contain a surfactant. Examples of surfactants include anionic surfactants (eg, sodium dodecylbenzene sulfonate, sodium lauryl sulfate, ammonium salts of polyoxyethylene alkyl ether sulfate), nonionic surfactants (eg, polyoxyethylene alkyl) Ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, etc.). These can be used alone or in combination of two or more.

  Examples of the penetrant include glycol ethers and acetylene glycol surfactants. Specific examples of glycol ethers include 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, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-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, propylene glycol mono-n-butyl ether , Dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol-iso-propyl ether These can be used, and can be used as a mixture of one or more of these.

  Among the glycol ethers, alkyl ethers of polyhydric alcohols are preferable, and ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene are particularly preferable. Glycol monoethyl ether or triethylene glycol monobutyl ether is preferred. More preferred is triethylene glycol monobutyl ether.

  The addition amount of the penetrant may be appropriately determined, but is preferably about 0.1 to 30% by weight, more preferably about 3 to 20% by weight.

  The ink composition according to the present invention may further contain a nozzle clogging preventive agent, an antiseptic, an antioxidant, a conductivity adjusting agent, a pH adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an oxygen absorber, and the like. it can.

  Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzthiazoline-3-one ( ICI's Proxel CRL, Proxel BND, Proxel GXL, Proxel XL-2, Proxel TN) and the like.

  Furthermore, examples of pH adjusters, solubilizers or antioxidants include amines such as diethanolamine, triethanolamine, propanolamine, morpholine and their modified products, potassium hydroxide, sodium hydroxide, lithium hydroxide, etc. Inorganic salts, ammonium hydroxide, quaternary ammonium hydroxide (tetramethylammonium, etc.), carbonates such as potassium carbonate, sodium carbonate, lithium carbonate and other phosphates, or N-methyl-2-pyrrolidone, urea, thiourea And L-ascorbic acid and salts thereof, such as ureas such as tetramethylurea, allophanates such as allophanate and methylallohanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret.

  In addition, the ink composition according to the present invention may contain an antioxidant and an ultraviolet absorber. Examples thereof include Tinuvin 328, 900, 1130, 384, 292, 123, 144, 622, and 770 of Ciba Geigy Corporation. 292, Irgacor 252 153, Irganox 1010, 1076, 1035, MD1024, lanthanide oxide, and the like.

  The ink composition according to the present invention can be produced by dispersing and mixing each of the above components by an appropriate method. Preferably, each component is first mixed with an appropriate disperser (eg, ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc.) Then, separately prepared resin (resin emulsion), water, water-soluble organic solvent, sugar, pH adjusting agent, preservative, antifungal agent and the like are added and sufficiently dissolved to prepare an ink solution. After sufficiently stirring, the target ink composition can be obtained by performing filtration in order to remove the coarse particle diameter and foreign matters that cause clogging.

  According to the present invention, there is provided a recording method for forming an image on a recording medium using the ink composition described above.

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

  In the examples, parts and% are based on weight unless otherwise specified.

1. Manufacture of colorants (1) Synthesis of dye monomers
While stirring 1.0 g (1 mmol) of a dye monomer copper phthalocyanine sodium tetrasulfonate derivative having an oxyethylene chain n = 6 in 5 ml of dimethylformamide, 0.5 g (4.8 mmol) of thionyl chloride was added dropwise. After dripping, it was made to react at 60 degreeC with a reflux tube for 2 hours. Thereafter, the reaction solution was cooled to room temperature, and then the reaction solution was slowly added dropwise with stirring to a hot reaction vessel charged with 5 g of New Frontier NF biisomer PEM6E (Daiichi Kogyo Seiyaku) and 10 g of pyridine. Subsequently, after stirring at room temperature for 12 hours, the reaction solution was added at once to 50 ml of methanol. The solution was subjected to suction filtration to collect a solid, and the solid was washed with methanol to obtain 0.3 g of dye monomer 1.

Oxyethylene chain n = 8 dye monomer New Frontier NF biisomer PEM6E (Daiichi Kogyo Seiyaku Co., Ltd.) 5 g and pyridine 10 g, instead of Blemmer PE350 (Nippon Yushi) 3 g and pyridine 2 g, The reaction was performed as described above. From this reaction solution, the solid content was recovered with a centrifuge (12,000 rpm, 10 minutes), and the solid content was washed with methanol to obtain 0.5 g of dye monomer 2.

While stirring 10 g (10 mmol) of a dye monomer copper phthalocyanine sodium tetrasulfonate derivative having an oxyethylene chain n = 10 in 50 ml of dimethylformamide, 5 g (48 mmol) of thionyl chloride was added dropwise. After dripping, it was made to react at 60 degreeC with a reflux tube for 3 hours. Thereafter, the reaction solution was cooled to room temperature, and then the reaction solution was slowly added dropwise with stirring to a hot reaction vessel charged with 25 g of MA-100A (manufactured by Nippon Emulsifier) and 10 g of pyridine. Subsequently, after stirring for 36 hours at room temperature, the reaction solution was added to 200 ml of methanol all at once. The reaction solution was centrifuged to collect solid content (12,000 rpm, 10 minutes), and the solid content was washed with methanol to obtain 4.7 g of dye monomer 3.

While stirring 10 g (10 mmol) of the dye monomer copper phthalocyanine sodium tetrasulfonate derivative having an oxyethylene chain n = 13 in 50 ml of dimethylformamide, 5 g (48 mmol) of thionyl chloride was added dropwise. After dripping, it was made to react at 60 degreeC with a reflux tube for 3 hours. Thereafter, the reaction solution was cooled to room temperature, and then the reaction solution was slowly added dropwise with stirring to a hot reaction vessel charged with 40 g of PEG600 (manufactured by Nakarai) and 10 g of pyridine. Subsequently, after stirring at room temperature for 36 hours, the reaction solution was added at once to 200 ml of methanol. The reaction solution was centrifuged to collect solids (12,000 rpm, 10 minutes), and the solids were washed with methanol to obtain 4.7 g of a compound. The obtained compound was added to 30 ml of pyridine with stirring, and 0.9 g (100 mmol) of methacryloyl chloride was added dropwise to the mixture. Subsequently, after stirring for 24 hours at room temperature, the reaction solution was added to 200 ml of methanol all at once. From this reaction solution, the solid content was recovered with a centrifuge (12,000 rpm, 10 minutes), and the solid content was washed with methanol to obtain 4.5 g of dye monomer 4.

(2) Manufacture of colorant The obtained pigment monomer 1 (20.0 g), a polymerization initiator (2.0 g), Disper BYK-190 (5.0 g), and water (353 g) are mixed, and a paint shaker is used. A dispersion of the dye monomer and the polymerization initiator was prepared by stirring for 2 hours. And styrene monomer (20.0 g) g (unsaturated ethylene monomer), surfactant (sodium laurylbenzenesulfonate) (25 g) and water (75 g) were added to the resulting dispersion (380 g), and nitrogen was added. The polymerization solution was reacted overnight at 70 ° C. with stirring so that the dye monomer and the styrene monomer were not suspended in the atmosphere, thereby obtaining Colorant 1 (500 g).

  In the same manner as above, coloring agents 2 to 4 were obtained using dye monomers 2 to 4.

(3) Preparation of ink composition Each ink composition shown in Table 1 below was mixed and filtered through a 10 µm membrane filter to obtain ink compositions 1 to 8 of Examples. The resulting composition had a colorant concentration of 2%. The numbers in the table are based on weight.

In the same manner as described above, a comparative ink composition 1 shown in Table 1 below was prepared by the following operation. First, a pigment and a styrene-acrylic acid copolymer (molecular weight 1600, acid value 150) are mixed and glass beads (diameter 1.7 mm, 1.5 times the weight of the mixture (weight) in a sand mill (manufactured by Yaskawa Seisakusho). ) For 2 hours. Thereafter, the glass beads were removed, other components were added, and the mixture was stirred at room temperature for 20 minutes. Filtration through a 10 μm membrane filter. The resulting composition had a colorant concentration of 2%. The numbers in the table are based on weight.

3. Evaluation (1) Bleeding evaluation Each ink composition obtained above is filled in all rows of ink cartridges of an ink jet printer (PX-V500, manufactured by Seiko Epson Corporation), and a dedicated paper (super fine paper, manufactured by Seiko Epson Corporation). ) 10-point century alphabet letters were printed. This printed matter was left for 48 hours in a constant temperature and humidity chamber at a temperature of 40 ° C. and a humidity of 80 RH%. Thereafter, the printed matter was taken out from the thermostatic chamber, and bleeding of the image (characters) was observed.

  As a result, the character with no bleeding was marked with ◯, and the character with bleeding was marked with x. The evaluation results were as shown in Table 2 below.

(2) Bronze evaluation Each ink composition obtained above is filled in all rows of ink cartridges of an ink jet printer (PX-G900, manufactured by Seiko Epson), and is used for exclusive paper (photo paper <gloss>, manufactured by Seiko Epson). ) Was printed at a duty of 100%. When the obtained printed material was irradiated with a white fluorescent lamp from 1 m above, the reflected light from the printed material was white, and the red light was ×. The evaluation results were as shown in Table 2 below.

(3) Clogging evaluation Each ink composition was filled in all rows of ink cartridges of an ink jet printer (PX-V500, manufactured by Seiko Epson Corporation). Next, the recording head was moved to the ink replacement position, and the ink cartridge was removed. The ink jet printer was left in a constant temperature and humidity chamber having a temperature of 40 ° C. and a humidity of 80 RH% for one week. After that, remove the inkjet printer from the temperature and humidity chamber, leave it for one day at room temperature and humidity (25 ° C, 40RH%), turn on the printer, and press the cleaning button several times until all ink nozzles return. It was.

As a result, the case where the cleaning was resumed within 4 cleanings was marked with ◯, and the case where the cleaning was resumed after 5 cleanings was marked with X. The evaluation results were as shown in Table 2 below.

Claims (21)

  A colorant comprising a polymer comprising a monomer unit having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via a sulfonic acid group. The monomer unit is represented by the following formula (I):

(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a dye compound, m represents an integer of 1 to 4, and n represents an integer of 1 to 20)
A colorant represented by   The colorant according to claim 1, wherein n in the formula 1 is 6-13. The R _{2 in the} formula (I) is a dye compound selected from a phthalocyanine skeleton, an azo skeleton, an anthraquinone skeleton, a dioxazine skeleton, a benzimidazolone skeleton, a molybdate skeleton, and a pyrazolone skeleton. Coloring agent.   The colorant according to any one of claims 1 to 4, wherein the polymer further comprises a monomer unit having an ethylenically unsaturated bond and not having the dye compound.   The monomer unit having an ethylenically unsaturated bond, and the monomer unit not having the dye compound includes one or more selected from the group consisting of a styrene monomer and a (meth) acrylic acid monomer. The colorant according to claim 5, comprising:   The colorant according to claim 5 or 6, wherein the polymer comprises 30 to 100 mol% of a monomer unit represented by the formula (I). A method for producing the colorant according to any one of claims 1 to 7,
Finely dispersing a nonionic polymerization initiator in an aqueous medium comprising a dispersion stabilizer;
A monomer having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via a sulfonic acid group in an aqueous medium in which the polymerization initiator is finely dispersed, and the ethylenically unsaturated Adding a monomer having a bond to prepare a polymerization solution;
Heating and polymerizing the polymerization solution while stirring so that the monomer is not suspended;
Comprising a method. A method for producing the colorant according to any one of claims 1 to 7,
A monomer having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via a sulfonic acid group to an aqueous medium containing a dispersion stabilizer and initiation of nonionic polymerization A step of finely dispersing the agent;
Adding a monomer having an ethylenically unsaturated bond to an aqueous medium in which the monomer and the polymerization initiator are finely dispersed, and preparing a polymerization solution;
Heating and polymerizing the polymerization solution while stirring so that the monomer is not suspended;
Comprising a method. A monomer having a structure in which a dye compound and a polyoxyether having an ethylenically unsaturated group are chemically bonded via the sulfonic acid group is represented by the following formula (II):

(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a dye compound, m represents an integer of 1 to 4, and n represents an integer of 1 to 20)
The method of Claim 8 or 9 represented by these.   The method according to claim 10, wherein n in the formula (II) is 6-13. The R _{2 in the} formula (II) is a dye compound selected from a phthalocyanine skeleton, an azo skeleton, an anthraquinone skeleton, a dioxazine skeleton, a benzimidazolone skeleton, a molybdate skeleton, and a pyrazolone skeleton. Method.   The method according to any one of claims 8 to 12, wherein the monomer further comprises a monomer having an ethylenically unsaturated bond and not having the dye compound.   The monomer having an ethylenically unsaturated bond, wherein the monomer not having the dye compound comprises one or more selected from the group consisting of a styrene monomer and a (meth) acrylic acid monomer The method according to claim 13.   An ink composition comprising the colorant according to any one of claims 1 to 7.   The ink composition according to claim 15, wherein the average particle diameter of the colorant is 100 nm or less.   The ink composition according to claim 15 or 16, further comprising a dispersion stabilizer.   The ink composition according to any one of claims 15 to 17, further comprising a wetting agent.   The ink composition according to any one of claims 15 to 18, further comprising a surfactant.   An ink jet recording method for performing printing by ejecting droplets of an ink composition and attaching the droplets to a recording medium, wherein the ink composition according to any one of claims 15 to 19 is used. An ink jet recording method using   A recorded matter recorded by the inkjet recording method according to claim 20.