JP2010006981A - Aqueous pigment dispersion for printing, ink composition and inkjet recording method - Google Patents

Abstract

【選択図】なしProvided is an aqueous pigment dispersion for printing which has excellent gloss and scratch resistance, gives a printed matter with high print quality, and also has excellent storage stability and ejection stability.
An aqueous pigment dispersion comprising (a) an aqueous medium, (b) a pigment, and (c) a dispersant. (C) The dispersant includes a water-soluble polymer obtained by copolymerizing a hydrophobic monomer, an oxyalkylene chain monomer represented by the following general formula (1), and an anionic monomer. The content weight ratio of the hydrophobic monomer structural unit and the oxyalkylene chain monomer structural unit constituting the water-soluble polymer is 0.15 to 0.80, and the content of the anionic monomer structural unit is 1 to 60 weight of the whole polymer. %, The polystyrene equivalent weight average molecular weight measured by GPC of the water-soluble polymer is 21,000 or more.

[Selection figure] None

Description

  The present invention relates to a printing solution suitable as a recording liquid for an inkjet printer or the like using a specific water-soluble polymer obtained by copolymerizing a hydrophobic monomer, a specific oxyalkylene chain monomer and an anionic monomer as a dispersant. The present invention relates to an aqueous pigment dispersion and a production method thereof, an ink composition containing the aqueous pigment dispersion, and an ink jet recording method using the ink composition.

  Inkjet printers are rapidly used for both personal use and business use due to the ease of full color, low noise, high-resolution images at a low price, and high-speed printing. It is becoming popular. At present, aqueous recording liquids are mainly used as recording liquids for ink jet printers, and printed materials with high resolution are being obtained.

  Conventionally, the aqueous recording liquid mainly contains a water-soluble dye and a liquid medium. However, the printed matter obtained with this aqueous recording liquid has insufficient water resistance, light resistance, ozone resistance and the like because the aqueous recording liquid contains a water-soluble dye. Therefore, in recent years, instead of such a dye, a pigment-dispersed aqueous recording liquid (hereinafter sometimes simply referred to as “ink”) in which a pigment is dispersed in an aqueous medium has been developed.

  In recent years, with the improvement of the resolution of printed matter, the amount of ink discharged from the ink discharge nozzle has decreased significantly. And since the request | requirement with respect to the printing speed improvement of an inkjet printer is increasing, higher pigment dispersion stability and low viscosity have been calculated | required with respect to the pigment dispersion-type aqueous recording liquid. On the other hand, a method has been proposed in which various water-soluble polymers, water-dispersible polymers, and the like are used as pigment dispersants in pigment-dispersed aqueous recording liquids.

  As this water-soluble or water-dispersible polymer, for example, a polymer containing an oxyalkylene chain is generally known. For example, as described below, it has been proposed to use a copolymer obtained by copolymerizing an oxyalkylene chain-containing monomer and a hydrophobic monomer as a polymer dispersant for a pigment with the aim of improving performance in inkjet applications.

  In Patent Document 1, in order to lower the viscosity and improve the redispersibility of the dispersion, specifically, the monomer having an ether structure of 5 to 70% by weight, the monomer having an acidic group of 10 to 45% by weight, and a pigment An ink for an ink jet printer using a copolymer of a monomer mixture composed of 5 to 50% by weight of a monomer having an affinity for the above as a dispersant has been proposed.

  In Patent Document 2, for the purpose of improving dispersion stability and printing speed, an aqueous dispersion containing fine particles coated with a resin having a polyether structure with an acid value of 5 to 70 KOHmg / g is proposed. Has been.

  In Patent Document 3, in order to improve the pigment dispersibility in a solvent-free state, specifically, a specific (meth) acrylic acid ester of 70 to 10% by weight, a specific oxyalkylene-containing monomer of 30 to 90% by weight, and A pigment dispersion using a nonionic polymer surfactant obtained by dividing and charging 0 to 50% by weight of other polymerizable vinyl monomers has been proposed.

In Patent Document 4, in order to improve printing density on plain paper, ejection stability, and long-term storage stability, specifically, 3 to 25 mol% of a monomer containing an oxyalkylene chain and α, β-ethylene are used. An aqueous pigment ink using a polymer containing 5 to 60 mol% of an unsaturated carboxylic acid has been proposed.
JP 2003-238849 A Japanese Patent Laid-Open No. 2003-238883 Japanese Patent Laid-Open No. 10-30010 JP-A-6-306317

  In recent years, in inkjet printers, the demand for pigment inks in the large-format and high-grade photo fields is increasing due to the high robustness of the printed matter. There is an increasing demand for those which simultaneously achieve stability, high gloss of printed matter on photographic paper, and high scratch resistance.

  However, none of the above patent documents suggests that the gloss of printed matter is improved, and according to the study by the present inventors, the dispersant shown in the above patent document was used. With the recording liquid prepared with the pigment dispersion, a printed matter satisfying both storage stability and ejection stability, and sufficient photographic high printing quality and scratch resistance could not be obtained.

  Accordingly, an object of the present invention is to provide an aqueous pigment dispersion for printing that is excellent in glossiness and scratch resistance, provides a printed matter with high print quality, and has excellent storage stability and ejection stability.

  In order to solve such problems, the present inventors have intensively studied an aqueous pigment dispersion for printing. As a result, the polymer dispersant is a water-soluble polymer obtained by copolymerizing a hydrophobic monomer, a specific oxyalkylene chain monomer, and an anionic monomer, and has a hydrophobic monomer structural unit / oxyalkylene chain. The content of the monomer structural unit (weight ratio) and the anionic monomer structural unit are within a specific range, and the weight average molecular weight (GPC (gel permeation chromatography) measured by GPC (gel permeation chromatography) above a specific value) By using a water-soluble polymer having a molecular weight), an aqueous pigment dispersion excellent in storage stability and ejection stability, and further, printed matter excellent in gloss, sharpness and scratch resistance on photographic paper. As a result, the present invention was completed.

  That is, the gist of the present invention is that, in an aqueous pigment dispersion containing (a) an aqueous medium, (b) a pigment, and (c) a dispersant, the (c) dispersant comprises at least one hydrophobic monomer and The hydrophobic monomer comprising a water-soluble polymer obtained by copolymerizing one or more oxyalkylene chain monomers represented by the general formula (1) and one or more anionic monomers, and constituting the water-soluble polymer The content weight ratio of the structural unit to the oxyalkylene chain monomer structural unit is 0.15 to 0.80, and the content of the anionic monomer structural unit constituting the water-soluble polymer is 1 to 60% by weight of the whole polymer. %, And the polystyrene-equivalent weight average molecular weight measured by GPC (gel permeation chromatography) of the water-soluble polymer is 21000 or more. Aqueous pigment dispersion (claim 1) consists in.

(Wherein R ¹ represents a vinyl group, an acryloyloxy group, an acryloylamino group, a methacryloyloxy group, a methacryloylamino group, an acrylamino group, a styryl group, a vinyl ether group, a vinylsilyl group, a cyanovinyl group, or a 2-cyanoacryloyl group. , R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group which may be substituted with an alkyl group, h and j are each independently an integer of 1 to 5, i and k are i + k is an integer satisfying 2 to 50.)

  Another gist of the present invention is the production of an aqueous pigment dispersion for printing, comprising the step of dispersing the (b) pigment and the (c) dispersant in a medium in the method for producing the aqueous pigment dispersion for printing. A method for producing an aqueous pigment dispersion for printing, wherein only water is used as the medium (claim 7).

  Still another subject matter of the present invention resides in an ink composition comprising the aqueous pigment dispersion for printing (claim 8).

  Still another subject matter of the present invention lies in an ink jet recording method (claim 9), characterized in that a droplet of the ink composition is ejected from an ink jet head and the droplet is adhered to a recording medium.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in glossiness, it is excellent in abrasion resistance, and it can provide the printed matter with high printing quality, and can provide the aqueous pigment dispersion for printing with favorable storage stability and discharge stability. In particular, the aqueous pigment dispersion for printing of the present invention can be suitably used for an ink composition as a recording liquid for an inkjet printer or the like, and the ink composition containing the aqueous pigment dispersion of the present invention can be used for high quality. In addition, a highly durable inkjet recording can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention does not exceed the gist thereof. These contents are not specified.

  In the following, “(meth) acrylate” means “acrylate and / or methacrylate”, and “(meth) acryl” means “acryl and / or methacryl”. The same applies to “(meth) acrylo”.

  In the case of a synthetic polymer, the “structural unit” means a unit derived from a monomer molecule used for production of the polymer by polymerization or copolymerization, or a unit in which they are modified by modification or the like. In the case of a natural polymer, it means a repeating unit or a unit modified by modification or the like.

[Aqueous pigment dispersion]
The printing aqueous pigment dispersion of the present invention comprises (a) an aqueous medium, (b) a pigment, and (c) a dispersant, and the (c) dispersant satisfies the following conditions (1) to (4): It is characterized by containing a water-soluble polymer to be filled (hereinafter sometimes referred to as “polymer (I)”).

(1) A water-soluble polymer obtained by copolymerizing one or more hydrophobic monomers and one or more oxyalkylene chain monomers represented by the following general formula (1) and one or more anionic monomers. .
(2) Content weight ratio of hydrophobic monomer structural unit and oxyalkylene chain monomer structural unit constituting the water-soluble polymer (content weight ratio of hydrophobic monomer structural unit and oxyalkylene chain monomer structural unit contained in polymer) = Hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit) is 0.15 to 0.80.
(3) The content of the anionic monomer structural unit constituting the water-soluble polymer is 1 to 60% by weight of the whole polymer.
(4) The polystyrene equivalent weight average molecular weight measured by GPC (gel permeation chromatography) of the water-soluble polymer is 21,000 or more.

(Wherein R ¹ represents a vinyl group, an acryloyloxy group, an acryloylamino group, a methacryloyloxy group, a methacryloylamino group, an acrylamino group, a styryl group, a vinyl ether group, a vinylsilyl group, a cyanovinyl group, or a 2-cyanoacryloyl group. , R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group which may be substituted with an alkyl group, h and j are each independently an integer of 1 to 5, i and k are i + k is an integer satisfying 2 to 50.)

  (C) By using the aqueous pigment dispersion of the present invention using the polymer (I) as a dispersant, the printed matter has high storage stability and ejection stability, and has high glossiness and high scratch resistance. Although the details of the reason for obtaining are not clear, it is considered as follows.

  In other words, the hydrophilic oxyalkylene chain contained in the polymer (I) interacts with each other while holding water on the paper to form a loosely widened network, and the surface of the printed material has high smoothness. The gloss of printed matter is improved by forming a film (condition (1)).

  However, low molecular weight polymers exhibit high mobility due to short polymer chains and thus have a large excluded volume space. In particular, in a state where an ink additive such as an aqueous organic solvent is added, and under a condition where the ink is heated, the motility becomes further intense, so that the excluded volume space is expanded. Under such conditions, the adsorbed polymer is gradually peeled off, and not only the stability of the recording liquid is lowered, but also the viscosity is increased and the ejection property is deteriorated, resulting in a decrease in gloss of the printed matter. For this reason, the molecular weight of the polymer needs to be large to some extent (condition (4)).

  In addition, if the value of the hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit (weight ratio) is too small, the adsorptivity of the polymer to the pigment is lowered and the dispersion stability is deteriorated. Conversely, if this value is too large, Due to the small number of oxyalkylene chain monomer structural units, the above-mentioned loosely widened network is not formed, and the gloss of the printed matter is deteriorated (condition (2)).

  Also, due to the interaction between the dispersant on the pigment surface and the paper, it is necessary to include a specific amount of an anionic monomer structural unit in order to achieve high scratch resistance (condition (3)).

  In the present invention, the value of the content weight ratio of the hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit of the polymer (I) used as the dispersant is 0.15 to 0.80, and the anionic monomer structural unit By setting the content to 1 to 60% by weight of the whole polymer, and further setting the weight average molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography) of the polymer to 21,000 or more, storage stability and ejection stability are also achieved. It is considered that a good pigment-dispersed recording liquid can be obtained, and a printed matter having excellent gloss and scratch resistance and good print quality can be obtained.

  In the present invention, the content and content ratio of the hydrophobic monomer structural unit, the oxyalkylene chain monomer structural unit and the anionic monomer structural unit contained in the polymer (I) are the same as those in the production of the polymer (I). In the actual polymer (I) obtained by analysis according to the analysis method described in the section of Examples described later, for the produced polymer (I), not by calculation from the charged amount of raw material monomer Content and content ratio.

{(C) Dispersant: Polymer (I)}
<Hydrophobic monomer>
The hydrophobic monomer as a copolymerization component of the polymer (I) is not particularly limited, and a conventionally known hydrophobic monomer can be used. In particular, the hydrophobic monomer is an aromatic ring as described below. It is preferable that it is a monomer containing an aromatic group and / or an aliphatic hydrocarbon group, such as a containing monomer and an aliphatic hydrocarbon group-containing monomer.

  The aromatic ring-containing monomer is an aromatic heterocyclic ring-containing monomer or an aromatic hydrocarbon ring-containing monomer. For example, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxyethylene glycol (meth) acrylate, 2-naphthyl ( (Meth) acrylate, 9-anthracenyl (meth) acrylate, 1-pyrenylmethyl (meth) acrylate styrene, vinylnaphthalene, styrene, α-methylstyrene, t-butylstyrene, p-methylstyrene, o-methoxystyrene, m-methoxystyrene , P-methoxystyrene, ot-butoxystyrene, mt-butoxystyrene, pt-butoxystyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene, vinyltoluene, ethyl Nirubenzen, 4-vinyl biphenyl, 1,1-diphenyl ethylene, vinyl phenol, vinyl benzoate, vinyl naphthalene, benzyl vinyl ether.

  Among these, from the viewpoint of pigment affinity, a monomer structure having an unsubstituted phenyl group such as benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, styrene, and α-methylstyrene is preferable. More preferred is methacrylate.

  The aliphatic hydrocarbon group contained in the aliphatic hydrocarbon group-containing monomer may be linear, cyclic, or branched.

  Examples of the monomer having a linear or branched aliphatic hydrocarbon group include the following.

Olefins such as ethylene, propylene, 1-butene and isobutene;
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, i-propyl (meth) acrylate, butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, amyl ( (Meth) acrylate, i-amyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, i-octyl (meth) acrylate, decyl (meth) acrylate, i-decyl (meth) acrylate, dodecyl ( (Meth) acrylate esters such as (meth) acrylate, i-dodecyl (meth) acrylate, stearyl (meth) acrylate, i-stearyl (meth) acrylate, and behenyl (meth) acrylate;
Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether;
Nitriles such as acrylonitrile and methacrylonitrile;
Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride;
Allyl compounds such as allyl acetate and allyl chloride;
Dicarboxylic acid ester derivatives such as maleic acid ester and itaconic acid ester;
Vinylsilyl compounds such as vinyltrimethoxysilane;
Vinyl esters such as vinyl acetate and isopropenyl acetate:

As a monomer having a cyclic aliphatic hydrocarbon group, for example,
Cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclononyl (meth) acrylate, cyclodecyl (meth) acrylate (Meth) acrylate esters such as isobornyl (meth) acrylate, norbornyl (meth) acrylate, adamantyl (meth) acrylate;
Cyclopentene, cycloheptene, cyclooctene, cyclododecene, 1,5-cyclooctadiene, cyclopentadiene, 1,5,9-cyclododecatriene, 1-chloro-1,5-cyclooctadiene, dicyclopentadiene, ethylidene norbornene, 5 -Cyclic olefins such as methyl norbornene-2-carboxylate and dimethyl 5-norbornene-2,3-dicarboxylate;
Etc.

  Among these, from the viewpoint of affinity with the pigment, a (meth) acrylate ester monomer having a linear alkyl structure and a monomer containing an aliphatic hydrocarbon group having a cyclic structure are preferable.

  These hydrophobic monomers may be used alone or in combination of two or more.

<Oxy-containing alkylene chain monomer>
The oxyalkylene chain monomer as a copolymerization component of the polymer (I) has an oxyalkylene chain structure in the molecule and is represented by the following general formula (1) (hereinafter, the following general formula ( The oxyalkylene chain monomer represented by 1) may be referred to as “oxyalkylene chain monomer (1)”.

(Wherein R ¹ represents a vinyl group, an acryloyloxy group, an acryloylamino group, a methacryloyloxy group, a methacryloylamino group, an acrylamino group, a styryl group, a vinyl ether group, a vinylsilyl group, a cyanovinyl group, or a 2-cyanoacryloyl group. , R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group which may be substituted with an alkyl group, h and j are each independently an integer of 1 to 5, i and k are i + k is an integer satisfying 2 to 50.)

  In the above general formula (1), the integer satisfying i + k = 2 to 50 is that when the sum of i and k is 1 or less, the gloss of the printed matter on the photo-dedicated paper is lowered. This is because the fixability is lowered.

R ² is preferably an alkyl group having 1 to 20 carbon atoms or a phenyl group which may be substituted with an alkyl group, and the alkyl group which the phenyl group of R ² may have is an alkyl group having 1 to 20 carbon atoms. An alkyl group is mentioned.

  Specific examples of the oxyalkylene-containing monomer (1) include polyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, lauroxy polyethylene glycol (meta ) Acrylate, stearoxy polyethylene glycol (meth) acrylate, nonylphenoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, poly (ethylene glycol-propylene glycol) (meth) acrylate, polyethylene Glycol-polypropylene glycol (meth) acrylate, poly ( Tylene glycol-tetramethylene glycol) (meth) acrylate, poly (propylene glycol-tetramethylene glycol) (meth) acrylate, propylene glycol-polybutylene glycol (meth) acrylate, octoxypolyethylene glycol-polypropylene glycol (meth) acrylate, steer Examples include loxypolyethylene glycol-polypropylene glycol (meth) acrylate, allyloxypolyethylene glycol-polypropylene glycol (meth) acrylate, and nonylphenoxypoly (ethylene glycol-propylene glycol) (meth) acrylate.

  As the oxyalkylene-containing monomer (1), the oxyalkylene chain is preferably an oxyethylene chain, and in particular, those represented by the following general formula (2) are effective in improving dispersion stability due to their high hydrophilicity. This is preferable. Specific examples of such oxyalkylene chain monomers include, for example, polyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, lauroxypolyethylene glycol ( Examples include meth) acrylate, stearoxy polyethylene glycol (meth) acrylate, nonylphenoxy polyethylene glycol (meth) acrylate, and phenoxy polyethylene glycol (meth) acrylate.

(In the formula, R ¹ and R ² have the same meanings as in general formula (1), and m is an integer of 2 to 50.)

In particular, among the general formula (2), R ¹ is preferably a (meth) acryloyloxy group. R ² is preferably an alkyl group having 1 to 20 carbon atoms. Moreover, it is preferable that m is an integer of 1-30. Specific examples of such oxyalkylene chain monomers include methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, lauroxypolyethylene glycol (meth) acrylate, stearoxypolyethylene glycol ( And (meth) acrylate.

R ² is more preferably an alkyl group having 1 to 10 carbon atoms, and particularly preferably an alkyl group having 1 to 5 carbon atoms.

  Among these, as the oxyalkylene chain monomer (1), methoxypolyethylene glycol (meth) acrylate is most preferable.

  These oxyalkylene chain monomers (1) may be used alone or in a combination of two or more.

<Anionic monomer>
Examples of the anionic monomer as a copolymerization component of the polymer (I) include those exemplified below, but are not limited thereto, and conventionally known ones can be used.

Carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, or salts thereof;
Vinyl sulfonic acid, allyl sulfonic acid, methacryl sulfonic acid, styrene sulfonic acid, 2-acrylamide ethane sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 2-methacrylamide ethane sulfonic acid, 2-methacrylamide-2-methyl Propanesulfonic acid, 2-acryloyloxyethanesulfonic acid, 3-acryloyloxypropanesulfonic acid, 4-acryloyloxybutanesulfonic acid, 2-methacryloyloxyethanesulfonic acid, 3-methacryloyloxypropanesulfonic acid, 4-methacryloyloxybutanesulfone Sulfonic acid monomers such as acids or salts thereof;
Vinylphosphonic acid, methacryloxyethyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, Phosphoric monomers such as dioctyl-2- (meth) acryloyloxyethyl phosphate or salts thereof:

  The anionic monomer is preferably a monomer having a carboxyl group (carboxylic acid) or a salt thereof, and more preferably acrylic acid or a salt thereof, from the viewpoint of printing quality such as low printing density or bleeding.

  The anionic monomer is preferably a salt. Of these, alkali metal salts and alkaline earth metal salts are more preferable, and sodium salts are particularly preferable.

  These anionic monomers may be used individually by 1 type, and 2 or more types may be mixed and used for them.

<Other polymerizable monomers>
The polymer (I) as the dispersing agent (c) according to the present invention comprises one or more hydrophobic monomers, one or more of the oxyalkylene chain monomers (1) and one or more anionic monomers. Any polymer may be used as long as it is polymerized, but another polymerized monomer may be further copolymerized.

  Other polymerizable monomers are not particularly limited, and conventionally known monomers can be used.

  Examples thereof include a monomer having a cationic group, a monomer having a nitrile group, and a hydrophilic nonionic monomer.

(Monomer having a cationic group)
The cationic group is a group that can have a cationic charge in an aqueous medium, and examples thereof include an amino group or a neutralized salt thereof, and a quaternized product.

  Examples of the monomer having a cationic group include the following.

Monomers having primary amino groups such as aminoethyl (meth) acrylate and aminopropyl (meth) acrylate;
Secondary such as methylaminoethyl (meth) acrylate, methylaminopropyl (meth) acrylate, ethylaminoethyl (meth) acrylate, ethylaminopropyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine A monomer having an amino group;
Monomers having a tertiary amino group such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate;
Neutralized salts of monomers having these primary to tertiary amino groups with hydrogen halide, sulfuric acid, nitric acid, organic acid, etc., quaternized products with alkyl halide, benzyl halide, dimethyl sulfuric acid, diethyl sulfuric acid and the like:

(Monomer having a nitrile group)
Examples of the monomer having a nitrile group include acrylonitrile and methacrylonitrile.

(Hydrophilic nonionic monomer)
Examples of the hydrophilic nonionic monomer include the following.

(Meth) acrylamide, N-alkyl (meth) acrylamide having 1 to 6 carbon atoms in the alkyl group, N, N-dialkyl (meth) acrylamide, C 1-3 in carbon number in the alkyl group, diacetone (meth) acrylamide, N -Methylol (meth) acrylamide, N-2-hydroxyethyl (meth) acrylamide, N, N-diethanol (meth) acrylamide, N-vinylacetamide, N-methyl-N-vinylacetamide, N-vinylformamide, N-methyl Amide group-containing monomers such as -N-vinylformamide, N- (2- (polyethylene glycol) ethyl) (meth) acrylamide, N, N- (2,2 '-(polyethylene glycol) diethyl) (meth) acrylamide;
2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, N-vinylpyrrolidone, 2-vinyl-2-oxazoline, 5-methyl-2-vinyl-2-oxazoline, N-vinyloxazolidone, 2-N-pyrrolidoneethyl A monomer having a heterocycle such as (meth) acrylate, N-vinylcaprolactam, 9-vinylcarbazole, N-vinylphthalimide, glycidyl (meth) acrylate, aziridine ring-containing monomer;
Monomers containing a hydroxyl group such as 2-hydroxyethyl (meth) acrylic acid ester, 2-hydroxypropyl (meth) acrylic acid ester, 2,3-dihydroxypropyl (meth) acrylate, 2-hydroxyethyl vinyl ether;
Glucose, mannose, galactose, glucosamine, mannosamine, galactosamine, etc., hexoses, arabinose, xylose, ribose, etc. Disaccharides such as mannobiose and sophorose, other oligosaccharides such as maltotriose, isomaltotriose, maltotetraose, maltopentaose, mannotriose and manninotriose, polysaccharides such as cellulose and modified cellulose A monomer having a structure as derived and having a glycosyl group, such as a monomer such as glucosylethyl methacrylate;
Monomers having a polyvinyl alcohol structure:

  Of these, hydrophilic nonionic monomers are preferred because of their high dispersion stability when used as dispersants. Among them, amide group-containing monomers, monomers having heterocycles, monomers containing hydroxyl groups, polyvinyl alcohol structures Among these, N-alkyl (meth) acrylamide, N-2-hydroxyethyl (meth) acrylamide, N-vinylpyrrolidone, 2-hydroxyethyl (meta) having 1 to 6 carbon atoms in the alkyl group are particularly preferable. ) An acrylic ester and a monomer having a polyvinyl alcohol structure are particularly preferred. Of these, N-2-hydroxyethyl (meth) acrylamide is most preferred.

  These other polymerizable monomers may be used alone or in a combination of two or more.

<Monomer composition>
Inclusion of hydrophobic monomer structural unit, oxyalkylene chain monomer (1) structural unit, anionic monomer structural unit and other polymerizable monomer structural units used as necessary in polymer (I) according to the present invention The amount of the hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit (weight ratio) is 0.15 to 0.8, and the content of the anionic monomer structural unit is 1 to 60% by weight of the whole polymer. It is essential to be.

  If the hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit (weight ratio) is less than 0.15, the adsorptive power of the polymer to the pigment will be weak, the viscosity will increase, and the discharge performance will deteriorate. If it is larger than .8, the glossiness of the printed matter is lowered. The hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit (weight ratio) is more preferably 0.2 to 0.8, and particularly preferably 0.3 to 0.8.

  Within the above weight ratio range, the content of the hydrophobic monomer structural unit is preferably 10% by weight or more and 40% by weight or less of the whole polymer. If the content of the hydrophobic monomer structural unit is too small, the polymer is difficult to be adsorbed to the pigment, and the liberated polymer increases and the viscosity increases. When there is too much content of a hydrophobic monomer structural unit, the water solubility of a polymer will fall and pigment dispersibility will worsen.

  Further, the content of the oxyalkylene chain monomer (1) structural unit is preferably 40% by weight or more and 80% by weight or less of the whole polymer. If the content of the oxyalkylene chain monomer (1) structural unit is too small, the gloss of the printed matter on the photographic paper is lowered, and if it is too much, the fixing property to the paper is lowered.

  Further, if the content of the anionic monomer structural unit is less than 1% by weight, the scratch resistance of the printed matter is lowered, and if it is more than 60% by weight, the glossiness of the printed matter is lowered. The content of the anionic monomer structural unit is preferably 1% by weight or more and 55% by weight or less of the whole polymer.

  The content of other polymerizable monomer structural units used as necessary is preferably 30% by weight or less of the whole polymer. By using other polymerizable monomers, effects such as improved dispersion stability and ejection properties may be obtained. However, if the content of other polymerizable monomer structural units is too large, the effect of the present invention is reduced. Resulting in. When other polymerizable monomer is used, its more preferable content is 0.1% by weight or more and 20% by weight or less of the whole polymer.

<Polymer structure>
The polymer structure of the polymer (I) according to the present invention may be any of a random copolymer, a diblock copolymer, a triblock or more multiblock copolymer, a gradient copolymer, a graft copolymer, a star copolymer, etc., among which a random copolymer is preferable. .

<Molecular weight>
The molecular weight of the polymer (I) as the dispersant (c) according to the present invention is 21000 or more as a weight average molecular weight (Mw). Especially, it is preferable that it is 21000 or more and 60000 or less, and, as for a weight average molecular weight, it is especially preferable that it is 21000 or more and 50000 or less. When the weight average molecular weight of the polymer (I) is too small, the solvent resistance of the aqueous pigment dispersion is lowered, and when the weight average molecular weight is too large, the viscosity is increased and the dischargeability is lowered.

  The number average molecular weight (Mw) of the polymer (I) is preferably 10,000 or more and 40,000 or less, and particularly preferably 12500 or more and 30000 or less.

  In addition, the value of molecular weight here is a value in terms of polystyrene measured by GPC (gel permeation chromatography).

<Water-soluble>
The “water-soluble polymer” as used herein refers to a polymer having a solubility in water at 25 ° C. of 5% by weight or more, and more preferably a polymer having a solubility of 10% by weight or more.
When such a water-soluble polymer is used as a polymer dispersant for an aqueous pigment dispersion, excellent pigment dispersibility can be obtained in the aqueous pigment dispersion. In addition, by using this aqueous pigment dispersion as a recording liquid, particularly an inkjet recording liquid, not only the dispersion stability of the pigment, but also the dischargeability of the recording liquid from the discharge nozzle, scratch resistance, print density, The effect that a printed matter having excellent gloss can be obtained is also obtained.

<Synthesis Method of Polymer (I)>
The method for synthesizing the polymer (I) is not particularly limited, and for example, a known polymerization method such as radical polymerization, ionic polymerization, polyaddition, polycondensation can be selected, and the polymer (I) was synthesized by these known methods. It may be a derivative or modified polymer. The polymer (I) is preferably synthesized using a radical polymerization method because the synthesis method is simple.

(Polymerization reaction solvent)
The radical polymerization reaction can be performed in the absence of a solvent or in the presence of a solvent, but is preferably performed in the presence of a solvent.

  Examples of the polymerization reaction solvent include ethers such as diethyl ether, tetrahydrofuran, diphenyl ether, anisole and dimethoxybenzene, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, acetonitrile, propionitrile and benzonitrile. Nitriles, acetone, methyl ethyl ketone, methyl isobutyl ketone, carbonyl compounds such as ethyl acetate, butyl acetate, ethylene carbonate, propylene carbonate, alcohols such as methanol, ethanol, propanol, isopropanol, n-butyl alcohol, t-butyl alcohol, isoamyl alcohol , Aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, methylene chloride, chloroform, chlorobenzene, carbon tetrachloride And halogenated hydrocarbons. Among these, preferred aqueous solvents as a polymerization reaction solvent.

  The aqueous solvent refers to a solvent obtained by mixing 100% water or water and a polar organic solvent at an arbitrary ratio. The polar organic solvent used here is not particularly limited as long as it can be mixed with water at an arbitrary ratio, and specific examples include methanol, ethanol, isopropanol, acetonitrile, acetone, dimethylformamide, dityl sulfoxide, tetrahydrofuran and the like. Of these, methanol, ethanol, and isopropanol are particularly preferable.

  These solvents may be a single solvent composed of only one kind or a mixed solvent composed of two or more kinds.

(Polymerization initiator)
A known radical polymerization initiator can be used for the radical polymerization reaction in the synthesis of the polymer. As the polymerization initiator, either a water-soluble polymerization initiator or an oil-soluble polymerization initiator can be used.

<Water-soluble polymerization initiator>
Examples of the water-soluble polymerization initiator include 2,2′-azobis (2-amidinopropane) dihydrochloride, 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis [2- (2-Imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2′-azobis [ N- (2-carboxyethyl) -2-methylpropionamide], 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl) propane} dihydrochloride, 2, 2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2 , 2′-azobis [2- (5-methyl) -Initiation of azo compound systems such as -imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (3,4,5,6, -tetrahydropyrimidin-2-yl) propane] dihydrochloride Oxidizing agents such as potassium persulfate, sodium persulfate, ammonium persulfate, and hydrogen peroxide alone, or sodium sulfite, sodium hyposulfite, ferrous sulfate, ferrous nitrate, sodium formaldehyde sulfoxylate, thiourea, etc. A redox initiator combined with a water-soluble reducing agent may be mentioned.
These may be used alone or in combination of two or more.

<Oil-soluble polymerization initiator>
Examples of oil-soluble polymerization initiators include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobiscyclohexane 1-carbonitrile, , 2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, dimethyl-2,2′-azobis (2-methylpropionate), Azo compound initiators such as 1,1′-azobis (1-acetoxy-1-phenylethane), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), acetylcyclohexylsulfonyl peroxide, Isobutyryl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, 2,4-dichlorobenzo Ruperoxide, t-butylperoxypivalate, 3,5,5-trimethylhexanonyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, stearoyl peroxide, propionitrile peroxide, succinic acid Peroxide, acetyl peroxide, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, parachlorobenzoyl peroxide, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, t- Butyl peroxylaurate, cyclohexanone peroxide, t-butyl peroxyisopropyl carbonate, 2,5-dimethyl-2,5-dibenzoyl peroxyhexane, t-butyl peroxyhexane -Oxyacetate, t-butylperoxybenzoate, diisobutyldiperoxyphthalate, methyl ethyl ketone peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, t-butylcumyl peroxide , T-butyl hydroperoxide, di-t-butyl peroxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide, pinane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide and cumene peroxide Peroxide polymerization initiators such as hydroperoxide (tret-butylhydroxyperoxide, cumenehydroxyperoxide, etc.), dialkyl peroxides (lauroyl peroxide, etc.) and peracids Oil-soluble peroxides such as diacyl (benzoyl peroxide, etc.), tertiary amines (triethylamine, tributylamine, etc.), naphthenates, mercaptans (mercaptoethanol, lauryl mercaptan, etc.), organometallic compounds (triethylaluminum, triethylboron, etc.) And an oil-soluble redox polymerization initiator used in combination with an oil-soluble reducing agent such as diethyl zinc).
These may be used alone or in combination of two or more.

(Additives such as chain transfer agents)
In the radical polymerization reaction, in addition to the above polymerization initiator, known materials such as a chain transfer agent, a chain terminator, and a polymerization accelerator can be added and used in order to adjust the resulting polymer to a preferred molecular weight.

(Polymerization conditions)
When conducting the polymerization reaction, raw materials such as monomers (hydrophobic monomers, oxyalkylene chain monomers (1), anionic monomers, and other polymerizable monomers used as necessary), polymerization reaction solvents, polymerization initiators, etc. The order of addition and the like is arbitrary, and examples include a method in which a monomer, a polymerization reaction solvent, and a polymerization initiator are charged all at once in a reaction vessel, and then the temperature is increased to perform a polymerization reaction. In this case, the monomer or the polymerization initiator may be additionally added as it is or in the form of a solution. As another method, a monomer solution, a polymerization reaction solvent is charged into a reaction vessel and the temperature is raised, and then a monomer solution containing a polymerization initiator, a polymerization reaction solvent, or a mixture thereof is continuously or divided. For example, and a polymerization reaction method.

  Among these, from the viewpoint of simplicity of operation, a method in which the polymerization reaction is performed by raising the temperature after charging the raw materials all at once is preferable.

  Although the usage-amount of a polymerization reaction solvent is not specifically limited, It is 1 weight part or more normally with respect to 100 weight part of monomers, Usually 2000 weight part or less, Preferably it is 1000 weight part or less.

  The amount of the polymerization initiator used varies depending on the type of the polymerization initiator used and is not particularly limited, but is usually 0.5 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the monomer.

  The polymerization temperature is not particularly limited, but is usually 0 ° C or higher, preferably 20 ° C or higher, and the upper limit is usually 200 ° C or lower, preferably 150 ° C or lower.

(Purification)
Although there is no particular problem even if the polymer obtained by polymerization is used as it is, it is preferably purified according to a conventional method and subjected to the subsequent pigment dispersion step. Purification methods include dropping the polymer solution into a solvent in which the polymer is insoluble and the monomer and polymerization initiator are soluble, reprecipitation purification by repeating the precipitation and filtration of the polymer, and the polymer and the polymer insoluble in the polymer solution and the polymerization initiator. Add a solvent that is soluble in water, remove the unreacted monomer and reaction solvent by fractional precipitation purification, heating distillation, vacuum distillation, etc. that repeat polymer precipitation and filtration, and then replace the solvent with water and / or aqueous solvent And a method of removing low molecular impurities and low molecular weight oligomer components using an ultrafiltration membrane or a dialysis membrane.

{(B) Pigment}
The (b) pigment used in the present invention is not particularly limited as long as it is appropriately selected from general pigments for each application. The following are representative examples of pigments.

Extender pigments such as calcium carbonate, kaolin clay, talc, bentonite, mica;
Metal oxide pigments typified by titanium oxide, zinc oxide, goethite, magnetite, chromium oxide, etc .;
Complex oxide pigments such as titanium yellow, titanium buff, antimony yellow, vanadium tin yellow, cobalt green, cobalt chrome green, manganese green, cobalt blue, cerulean blue, manganese blue, tungsten blue, Egyptian blue, cobalt black and the like;
Sulfide pigments such as litbon, cadmium red yellow and cadmium red;
Phosphate pigments typified by mineral violet, cobalt violet, lithium cobalt phosphate, sodium cobalt phosphate, potassium potassium phosphate, cobalt ammonium phosphate, nickel phosphate, copper phosphate;
Chromate pigments such as yellow lead and molybdate orange;
Metal complex pigments typified by ultramarine and Prussian blue;
Metal powder pigments such as aluminum paste, bronze powder, zinc powder, stainless steel flakes and nickel flakes;
Carbon black, bismuth oxychloride, basic carbonate, titanium dioxide, coated mica, ITO (indium tin oxide), ATO (antimony tin oxide) and other inorganic pigments such as pearlescent pigments and nacreous conductive pigments ;
Quinacridone pigment, quinacridone quinone pigment, dioxazine pigment, phthalocyanine pigment, anthrapyrimidine pigment, ansanthrone pigment, indanthrone pigment, flavanthrone pigment, perylene pigment, diketopyrrolopyrrole pigment, perinone Organic pigments such as pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, metal complex pigments, azomethine pigments or azo pigments:

  Specific examples of the pigment include pigments having the following pigment numbers and known carbon blacks generally used in the color material field. Note that terms such as “CI Pigment Red 2” mentioned below mean a color index (CI).

  Red colorant: C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 14, 15, 16, 17, 21, 22, 23, 31, 32, 37, 38, 41, 47, 48, 48: 1, 48: 2, 48: 3, 48: 4, 49, 49: 1, 49: 2, 50: 1, 52: 1, 52: 2, 53, 53: 1, 53: 2, 53: 3, 54, 57, 57: 1, 57: 2, 58, 58: 4, 60, 63, 63: 1, 63: 2, 64, 64: 1, 68, 69, 81, 81: 1, 81: 2, 81: 3, 81: 4, 83, 88, 90: 1, 101, 101: 1, 104, 108, 108: 1, 109, 112, 113, 114, 122, 123, 144, 146, 147, 149, 151, 166, 168, 169, 170, 172, 173, 174, 175, 176, 177, 78, 179, 181, 184, 185, 187, 188, 190, 193, 194, 200, 202, 206, 207, 208, 209, 210, 214, 216, 220, 221, 224, 230, 231, 232, 233, 235, 236, 237, 238, 239, 242, 243, 245, 247, 249, 250, 251, 253, 254, 255, 256, 257, 258, 259, 260, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276;

  Blue colorant: C.I. I. Pigment Blue 1, 1: 2, 9, 14, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17, 19, 25, 27, 28, 29, 33, 35, 36, 56, 56: 1, 60, 61, 61: 1, 62, 63, 66, 67, 68, 71, 72, 73, 74, 75, 76, 78, 79;

  Green colorant: C.I. I. Pigment Green 1, 2, 4, 7, 8, 10, 13, 14, 15, 17, 18, 19, 26, 36, 45, 48, 50, 51, 54, 55;

  Yellow colorant: C.I. I. Pigment Yellow 1, 1: 1, 2, 3, 4, 5, 6, 9, 10, 12, 13, 14, 16, 17, 23, 24, 31, 32, 34, 35, 35: 1, 36, 36: 1, 37, 37: 1, 40, 41, 42, 43, 48, 53, 55, 61, 62, 62: 1, 63, 65, 73, 74, 75, 81, 83, 87, 93, 94, 95, 97, 100, 101, 104, 105, 108, 109, 110, 111, 116, 119, 120, 126, 127, 127: 1, 128, 129, 133, 134, 136, 138, 139, 142, 147, 148, 150, 151, 153, 154, 155, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 172, 173 174, 175, 176, 180, 181, 182, 183, 184, 185, 188, 189, 190, 191, 191: 1, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202, 203, 204, 205, 206, 207, 208, 215;

  Orange colorant: C.I. I. Pigment Orange 1, 2, 5, 13, 16, 17, 19, 20, 21, 22, 23, 24, 34, 36, 38, 39, 43, 46, 48, 49, 61, 62, 64, 65, 67, 68, 69, 70, 71, 72, 73, 74, 75, 77, 78, 79;

  Violet colorant: C.I. I. Pigment Violet 1, 1: 1, 2, 2: 2, 3, 3: 1, 3: 3, 5, 5: 1, 14, 15, 16, 19, 23, 25, 27, 29, 31, 32, 37, 39, 42, 44, 47, 49, 50

  Brown colorant: C.I. I. Pigment Brown 1, 6, 11, 22, 23, 24, 25, 27, 29, 30, 31, 33, 34, 35, 37, 39, 40, 41, 42, 43, 44, 45

  Black colorant: C.I. I. Pigment Black 1, 31, 32

  Among the above pigments, red pigments preferably include quinacridone pigments, xanthene pigments, perylene pigments, antanthrone pigments, and monoazo pigments. I. Pigment Red-5, -7, -12, -112, -81, -122, -123, 146, -147, -168, -173, -202, -206, -207, -209, C.I. I. And CI Pigment Violet-19. Among these, the solid solution which consists of a quinacridone-type pigment and two or more types of quinacridone-type pigments is more preferable from the surface of a pigment's stability and hue.

  Of the above-mentioned pigments, monoazo pigments and disazo pigments are preferable as yellow pigments because color development as printed matter is better than other pigments. Among them, C.I. I. Pigment-1, -3, -16, -17, -74, -95, -120, -128, -151, -155, -175, -215 are particularly preferred from the viewpoint of the color, and among them, C . I. CI Pigment Yellow-74 and -155 are non-halogen compounds, and are particularly preferable from the viewpoint of little influence on the environment and hue.

  Of the above-mentioned pigments, a blue pigment is preferable, and a copper phthalocyanine pigment is preferable because color development as a printed matter is better than other pigments. Among them, C.I. I. Pigment Blue-15: 3 is preferable from the viewpoints of stability and hue.

  Further, as the carbon black used in the present invention, various carbon blacks such as acetylene black, channel black and furnace black can be used. Among these, channel black or furnace black is preferable, and furnace black is particularly preferable.

The DBP oil absorption amount of the above carbon black is preferably in the range of 30 to 250 ml / 100 g, more preferably in the range of 30 to 100 ml / 100 g, more preferably in the range of 30 to 70 ml / 100 g, from the viewpoint of glossiness in photographic paper. A range is particularly preferred.
The volatile content is preferably 8% by weight or less, particularly preferably 4% by weight or less.
From the viewpoint of the storage stability of the recording liquid, the pH is preferably 3 or more, more preferably 6 or more, and the upper limit is preferably 11 or less, particularly preferably 9 or less.
The BET specific surface area is usually 100 m ² / g or more, preferably 150 m ² / g or more, and the upper limit is preferably 700 m ² / g or less, particularly preferably 600 m ² / g or less.

  Here, the DBP oil absorption is a value measured by the method of JISK6221A, the volatile content is a value measured by the method of JISK6221, pH is a value measured by a glass electrode meter with a mixture of carbon black and distilled water, and the BET specific surface area is that of JISK6217. It is the value measured by the method.

  From the viewpoint of safety, it is preferable to use carbon black in which the polycyclic aromatic component is reduced by baking at 600 to 1500 ° C. or washing with water, warm water, a solvent, or the like. In particular, baking at a high temperature is more preferable because the functional group on the surface of the carbon black is removed, whereby the dispersant is more efficiently adsorbed more firmly on the surface of the carbon black.

  Specific examples of the carbon black include products shown in the following (1) to (4).

(1) # 2700B, # 2650, # 2650B, # 2600, # 2600B, 2450B, 2400B, # 2350, # 2300, # 2300B, # 2200B, # 1000, # 1000B, # 990, # 990B, # 980, # 980B, # 970, # 960, # 960B, # 950, # 950B, # 900, # 900B, # 850, # 850B, MCF88, MCF88B, MA600, MA600B, # 750B, # 650B, # 52, # 52B, # 50, # 47, # 47B, # 45, # 45B, # 45L, # 44, # 44B, # 40, # 40B, # 33, # 33B, # 32, # 32B, # 30, # 30B, # 25, # 25B, # 20, # 20B, # 10, # 10B, # 5, # 5B, CF9, CF9B, # 95, # 260, MA77 MA77B, MA7, MA7B, MA8, MA8B, MA11, MA11B, MA100, MA100B, MA100R, MA100RB, MA100S, MA230, MA220, MA200RB, MA14, # 3030B, # 3040B, # 3050B, # 3230B, # 3350B (and above, Mitsubishi Chemical company product).

(2) Monarch 1400, Black Pearls 1400, Monarch 1300, Black Pearls 1300, Monarch 1100, Black Pearls 1100, Monarch 1000, Black Pearls 1000, Monarch 900, Black Pearl 900 800, Monarch 700, Black Pearls 700, Black Pearls 2000, Vulcan XC72R, Vulcan XC72, Vulcan PA90, Vulcan 9A32, Mogul L, Black Pearls L, Regal 660R, R gal 660, Black Pearls 570, Black Pearls 520, Regal 400R, Regal 400, Regal 330R, Regal 330, Regal 300R, Black Pearls 490, Black Pearls 480, Black Pearls 480, Black Pearls 480, Black Pearls 480, Black Pearls 480, Black Pearls 480, Black Pearls 480, Black Pearls 480, Black Pearls 480 Black Pearls 420, Black Pearls 410, Regal 350R, Regal 350, Regal 250R, Regal 250, Regal 99R, Regal 99I, Elftex Pellets 115, Elftex 8, Elftex 5, Elftex 12, Mftex 12 ch 280, Black Pearls 280, Black Pearls 170, Black Pearls 160, Black Pearls 130, Monarch 120, Black Pearls 120 (above, products of Cabot Corporation).

(3) Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Special Black 4, Special Black 4A, Special Black 4A, Special Black 4W, Color Black FW2V, Color Black FW2V, Color Black FW2 V, Printex 150T, Printex 140U, Printex 140V, Printex 95, Printex 90, Printex 85, Printex 80, Printex 75, Printex 55, Printex 45, Printex 40, Printex 40, Princex ntex 60, Printex XE, Printex L6, Printex L, Printex 300, Printex 30, Printex 3, Printex 35, Printex 25, Printex 200, Printex A, Printex G, Stex 100 (above, Degussa product).

(4) Raven 7000, Raven 5750, Raven 5250, Raven 5000 ULTRA, Raven 3500, Raven 2000, Raven 1500, Raven 1250, Raven 1250, Raven 10170, Raven 1170, Raven 1170, Raven 1170, Raven 1170, Raven 1170, Raven 1170, Raven 1170, Raven 1170, Raven 1170, Raven 1170 Raven 1000, Raven 890H, Raven 890, Raven 850, Raven 790 ULTRA, Raven 760 ULTRA, Raven 520, Raven 500, Raven 450, Raven 430, Raven 420, Raven 420, Raven 420, Raven 420, Raven 420 ULTRA, Raven H2O, Raven C ULTRA (or more, Columbia's products).

  As the pigment according to the present invention, one of the above pigments may be used alone, or two or more of them may be used in combination. It can also be used in combination with other color materials.

  The shape of the pigment may be any form such as paste, powder, solid solution and the like.

The primary particle size of these pigments may be arbitrarily set according to the purpose, but is usually 10 nm or more, and preferably 500 nm or less, more preferably 300 nm or less, still more preferably 200 nm or less, particularly Preferably it is 100 nm or less.
Here, the primary particle diameter of the pigment is an arithmetic average diameter (number average) measured by an electron microscope.

The average dispersed particle size of the pigment in the aqueous pigment dispersion of the present invention is usually 300 nm or less, preferably 200 nm or less. Moreover, as a minimum, it is 20 nm or more normally.
The average dispersed particle size can be measured using an electron microscope such as SEM or TEM, or can be measured using a commercially available dynamic light scattering measurement device.

  The pigment is not chemically modified, and a pigment that does not contain impurities other than the pigment, such as a crystallization inhibitor for promoting the reduction in the particle size of the pigment, It is preferable because it does not inhibit the adsorption. However, in order to give the pigment self-dispersibility, a pigment having self-dispersibility which has been subjected to known chemical modification in advance can also be used. That is, the pigment used in the aqueous pigment dispersion of the present invention may be an untreated pigment or a pigment whose surface is chemically modified as described above, and any pigment can be used.

{(A) Aqueous medium}
Examples of the aqueous medium (a) used in the aqueous pigment dispersion of the present invention include water and / or a water-soluble organic solvent. Although it will not specifically limit if it is generally used for this use as a water-soluble organic solvent, Specifically, it is a thing with a vapor pressure smaller than water, and the following are mentioned.

Ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propylene glycol, isopropylene glycol, polypropylene glycol, pentamethylene glycol, trimethylene glycol, butylene Glycol, isobutylene glycol, thiodiglycol, 1,2-hexanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 1,2-pentanediol, 1,5-pentanediol, 2- Methyl-2,4-pentanediol, 1,3-propanediol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, 2 Butene-1,4-diol, polyhydric alcohols such as glycerin;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol mono-t-butyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monophenyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl Ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, Lopylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol-t-butyl ether, propylene glycol monopropyl ether, propylene glycol isopropyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene Polyhydric alcohol ethers such as glycol monobutyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoisopropyl ether;
Ketones such as acetonylacetone;
Esters such as γ-butyrolactone, diacetin, triethyl phosphate;
Lower alkoxy alcohols such as 2-methoxyethanol and 2-ethoxyethanol;
Amines such as ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, triethylenetetramine, tetraethylenepentamine, pentamethyldiethylenetriamine;
Amides such as formamide, N, N-dimethylformamide, N-methylformamide, N, N-dimethylacetamide;
2-pyrrolidone, N-ethylpyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, morpholine, N-ethylmorpholine, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, imidazole, methylimidazole, hydroxyimidazole , Heterocycles such as dimethylaminopyridine, 1,3-propane sultone, hydroxyethylpiperazine, piperazine;
Sulfoxides such as dimethyl sulfoxide;
Sulfones such as sulfolane:

  These may be used alone or in combination of two or more.

  The aqueous medium used in the present invention is preferably water or a mixture of water and a water-soluble organic solvent as described above.

{Aqueous pigment dispersion composition}
The aqueous pigment dispersion of the present invention comprises the above-mentioned (a) aqueous medium, (b) pigment, and (c) polymer (I) as a dispersant.

  In the aqueous pigment dispersion of the present invention, one type of polymer (I) may be contained alone, or two or more types may be contained.

  The pigment concentration in the aqueous pigment dispersion of the present invention is usually 30% by weight or less, preferably 20% by weight or less. Here, if the pigment concentration is too high, the pigment becomes poorly dispersed, the viscosity of the dispersion increases, the dispersion becomes gelled, and the dispersion cannot be used due to dispersion failure. If the pigment concentration is too low, a sufficient printing density will not be obtained when ink is formed. Therefore, the pigment concentration is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight or more. .

  The weight ratio of the pigment in the aqueous pigment dispersion of the present invention to the polymer (I) as the dispersant according to the present invention may be appropriately selected and determined. Generally, 1 part by weight of the pigment is used. The polymer (I) (the total when two or more polymers (I) are included) is 0.01 parts by weight or more, especially 0.05 parts by weight or more, particularly 0.1 parts by weight or more. The upper limit is usually 2 parts by weight or less, preferably 1.5 parts by weight or less. If the amount of the polymer (I) is too small, the dispersion stability is lowered. If the amount of the polymer (I) is too large, the viscosity of the dispersion liquid and the ink is increased and the dischargeability is lowered.

  The aqueous pigment dispersion of the present invention may contain components other than the above-mentioned aqueous medium, pigment, and polymer (I) as a dispersant, and in particular, the ink composition of the present invention as described later. Polymers other than the polymer (I) exemplified as other additives that can be contained in the product, and other components may be contained.

[Ink composition (recording liquid)]
The ink composition of the present invention containing the aqueous pigment dispersion of the present invention characterized by containing the polymer (I) described above as a dispersant exhibits particularly excellent effects as a recording liquid, particularly an inkjet recording liquid.

  The ink composition of the present invention used as a recording liquid (hereinafter referred to as “recording liquid of the present invention”) adjusts the colorant concentration of the above-described aqueous pigment dispersion of the present invention as necessary, and further uses Depending on the conditions, various additives are added.

  As the colorant, in addition to the pigment in the aqueous pigment dispersion of the present invention described above, it is further dispersed with a self-dispersing pigment surface-treated for purposes such as toning, a dye, a surfactant, a polymer dispersant, etc. It may also contain added pigments or dyes.

  The concentration of the total colorant in the recording liquid of the present invention is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and the upper limit is 20% by weight, based on the total amount of the recording liquid. Hereinafter, it is preferably 15% by weight or less, particularly preferably 10% by weight or less. If the colorant concentration is too high, the viscosity is increased and the discharge property is deteriorated. If the colorant concentration is too low, the print density is too low. On the other hand, the amount of the colorant added to the aqueous pigment dispersion is usually 100 parts by weight or less, preferably 75 parts by weight or less, more preferably 50 parts by weight or less with respect to 100 parts by weight of the pigment in the aqueous pigment dispersion. The amount is particularly preferably 25 parts by weight or less. If the additional amount of the colorant is too large, the effect of the present invention is reduced.

  The solvent used in the recording liquid of the present invention preferably contains water and a water-soluble organic solvent, and can further contain other components as desired.

  The concentration of the water-soluble organic solvent in the recording liquid of the present invention may be appropriately selected and determined. Usually, it is preferably 1% by weight or more and 45% by weight or less, more preferably 40% by weight or less with respect to the recording liquid. In addition, the content of water in the recording liquid may be an amount that can appropriately set the concentration of the above-described colorant, water-soluble organic solvent, and optional additive components described below.

  As the water-soluble organic solvent, those exemplified as the aqueous medium of the aqueous pigment dispersion of the present invention described above can be used.

  The recording liquid of the present invention may contain various additives as necessary within the range not impairing the effects of the present invention.

  Examples of such additives include recording liquids such as penetration enhancers, surface tension modifiers, hydrotropic agents, pH adjusters, chelating agents, preservatives, viscosity modifiers, humectants, antifungal agents, and rust inhibitors. Known additives can be used.

  The content of these additives in the recording liquid of the present invention is generally 30% by weight or less, particularly preferably 15% by weight or less, based on the total amount of the recording liquid.

  Examples of penetration enhancers include lower alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol and pentanol, carbitols such as ethylene glycol monobutyl ether and triethylene glycol monobutyl ether glycol ether, and surfactants 1 A seed | species or 2 or more types is mentioned.

  As the surfactant, any one or more of nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, polymer surfactants and the like can be used. Can be used. Of these, nonionic surfactants, anionic surfactants and polymer surfactants are preferred.

  Nonionic surfactants include, for example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, polyoxyethylene derivatives, oxyethylene / oxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid Examples thereof include esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, acetylene glycols, and acetylene alcohols.

  Examples of the anionic surfactant include fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether sulfonates, alkyl phosphates, polyoxyethylene alkyl sulfates. Examples include ester salts, polyoxyethylene alkylaryl sulfate esters, alkane sulfonates, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl phosphates, α-olefin sulfonates, and the like.

  Polymeric surfactants include polyacrylic acid, styrene / acrylic acid copolymer, styrene / acrylic acid / acrylic acid ester copolymer, styrene / maleic acid copolymer, styrene / maleic acid / acrylic acid ester copolymer, styrene / methacrylic acid. Examples include copolymers, styrene / methacrylic acid / acrylic acid ester copolymers, styrene / maleic acid half ester copolymers, styrene / styrene sulfonic acid copolymers, vinyl naphthalene / maleic acid copolymers, vinyl naphthalene / acrylic acid copolymers, and salts thereof.

  Examples of the cationic surfactant include, but are not limited to, tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like.

  In addition, silicone surfactants such as polysiloxane oxyethylene adducts, fluorine surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, oxyethylene perfluoroalkyl ethers, rhamnolipids, lysolecithins, etc. Surfactants such as biosurfactants can also be used.

  The content of these surfactants may be selected and determined as appropriate. Usually, by adding in the range of 0.001 wt% or more and 5 wt% or less with respect to the recording liquid, the quick drying property and the print quality of the printed matter can be further improved.

  Examples of the surface tension adjusting agent include alcohols such as diethanolamine, triethanolamine, glycerin, and diethylene glycol, nonions, cations, anions, and amphoteric surfactants.

  As the hydrotropic agent, one or more of urea, alkylurea, ethyleneurea, propyleneurea, thiourea, guanidate, tetraalkylammonium halide and the like are preferable.

  As a humectant, 1 type (s) or 2 or more types, such as glycerol and diethylene glycol, can also be added as what also serves as a water-soluble organic solvent.

  Furthermore, a solid moisturizing agent (a water-soluble substance having a water retaining function and solid at 25 ° C.) can be added. Preferred solid humectants include saccharides, sugar alcohols, hyaluronate, trimethylolpropane, 1,2,6-triol and the like. Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), and polysaccharides. Specifically, glucose, fructose, ribose, xylose, arabinose, galactose, sorbit, maltose, and lactose. , Sucrose, trehalose and the like. Examples of sugar alcohols include maltitol, sorbitol, xylitol, and the like, and one or more of these solid humectants can be added.

  Although it does not specifically limit as a chelating agent, 1 type (s) or 2 or more types, such as a sodium salt of ethylenediaminetetraacetic acid, a diammonium salt of ethylenediaminetetraacetic acid, are used. These are preferably used in the range of 0.005 wt% to 0.5 wt% with respect to the recording liquid.

  The antifungal agent is not particularly limited, but sodium dehydroacetate, dichlorophen, sorbic acid, sodium benzoate, p-hydroxybenzoate, 1,2-Benzisothiazoline-3-one (product name: Proxel) GXL (manufactured by Arch Chemicals)) or the like is used. These are preferably contained in the range of 0.05 wt% to 1 wt% with respect to the recording liquid.

  Further, in order to adjust the pH of the recording liquid and obtain the stability of the recording liquid, it is not particularly limited, but sodium hydroxide, potassium hydroxide, lithium hydroxide, nitric acid, ammonia, diethanolamine, triethanolamine, etc. PH adjusters and buffer solutions such as phosphoric acid can be used.

  The pH of the recording liquid is usually in a neutral to alkaline range, and is preferably adjusted to about pH 6 to 11.

  Further, the recording liquid of the present invention may contain a polymer other than the polymer (I) as long as the effects of the present invention are not impaired. Specific examples of such polymers include vinyl resins such as acrylic resins, styrene-acrylic resins, polyvinyl alcohol resins, vinyl acetate resins, and polyester resins, polyamide resins, polyurethane resins, and epoxy resins. And known resins such as butadiene-based resins, petroleum-based resins, and fluorine-based resins. Among these, water-soluble or water-dispersible resins are preferable. Of these, polyvinyl alcohol resins and acrylic resins are preferable, and polyvinyl alcohol resins are particularly preferable. Among the polyvinyl alcohol-based resins, the following resins are more preferable from the viewpoint of storage stability of the recording liquid.

  Preferable polyvinyl alcohol resins include those containing a vinyl alcohol structural unit represented by the following general formula (3) and a hydrophobic group in the polymer (hereinafter referred to as “polymer (II)”). In the polymer (II), only one kind of vinyl alcohol structural unit represented by the following general formula (3) may be contained, or two or more kinds may be contained. Moreover, only 1 type of hydrophobic groups may be contained and 2 or more types may be contained.

(Wherein R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms)

Specific examples of R ³ in the general formula (3) include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, sec-butyl group, pentyl group, isopentyl group, neopentyl group. And alkyl groups such as a group, t-pentyl group, and hexyl group. Among these, a hydrogen atom or an alkyl group having a small number of carbon atoms is preferable, specifically, an alkyl group having 1 to 3 carbon atoms is preferable, and a hydrogen atom or a methyl group is particularly preferable.

  Examples of the vinyl alcohol structural unit represented by the general formula (3) include vinyl alcohol, α-methyl vinyl alcohol, α-ethyl vinyl alcohol, α-propyl vinyl alcohol, α-butyl vinyl alcohol, α-hexyl vinyl alcohol and the like. The structural unit derived from is mentioned.

  On the other hand, examples of the hydrophobic group contained in the polymer (II) include aliphatic hydrophobic groups such as alkyl groups, alkenyl groups and alkynyl groups, alicyclic hydrophobic groups such as cyclohexyl groups and isobornyl groups, and phenyl groups. And aromatic hydrophobic groups such as a naphthyl group. These groups may be unsubstituted or further have a substituent.

  In order to introduce the vinyl alcohol structural unit represented by the general formula (3) and the hydrophobic group into the polymer structure, a polymerizable monomer that induces a vinyl alcohol structural unit such as a vinyl ether monomer or a vinyl ester monomer and a hydrophobic group are introduced. After polymerizing with a polymerizable monomer having a functional group and introducing them into the polymer structure, the side chain portion of the vinyl ether monomer or vinyl ester monomer is modified by the above general formula (3 It may be converted into a vinyl alcohol structural unit represented by

  Examples of vinyl ether monomers that derive the vinyl alcohol structural unit represented by the general formula (3) include methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, Examples thereof include n-hexadecyl vinyl ether, 2-chloroethyl vinyl ether, phenyl vinyl ether, benzyl vinyl ether, and trimethylsilyl vinyl ether.

  Examples of the vinyl ester monomer for deriving the vinyl alcohol structural unit include vinyl acetate, vinyl propionate, vinyl laurate, vinyl stearate, vinyl pivalate, vinyl formate, vinyl caproate, vinyl caprate, myristine. Vinyl acetate, vinyl palmitate, vinyl 2-ethylhexanoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetate, vinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate, these α -Substituent etc. are mentioned.

  Further, the vinyl alcohol structural unit and the hydrophobic group represented by the general formula (3) contained in the polymer (II) are a main chain and / or a side chain portion in the polymer structure by a modification reaction or a modification reaction. May be introduced.

  The polymer (II) only needs to contain a vinyl alcohol structural unit represented by the general formula (3) and a hydrophobic group, and other oxyalkylene groups, hydroxyl groups, amide groups, pyrrolidone groups, oxazoline groups, etc. Representative hydrophilic groups, carboxylic acid groups, sulfonic acid groups, acidic groups typified by phosphoric acid groups, basic groups typified by amino groups, pyridinium groups, imidazolium groups, and acidic groups and basic groups And an ionic dissociation group which is a salt thereof. Among these, an ionic dissociation group structure that is an acidic group, a basic group, or a salt thereof is preferably included.

  The hydrophobic group and the ionic dissociation group contained in the polymer (II) are preferably contained in the polymer structure as monomer structural units. That is, the polymer (II) is particularly preferably a polymer including a vinyl alcohol structural unit represented by the general formula (3), a monomer structural unit having a hydrophobic group, and a monomer structural unit having an ionic dissociation group. .

  The form of the polymer (II) is not particularly limited, such as a random copolymer, a diblock copolymer, a triblock or more multiblock copolymer, a gradient copolymer, a graft copolymer, a star copolymer, etc. Among them, a block copolymer is preferable.

If the molecular weight of the polymer (II) is too large, the viscosity of the dispersion tends to increase. If the molecular weight is too small, the storage stability of the recording liquid decreases. Therefore, polyethylene glycol measured by GPC (gel permeation chromatography). The weight average molecular weight (Mw) in terms of conversion is preferably 10,000 or more, particularly 15000 or more, 70,000 or less, particularly 60000 or less.
The number average molecular weight (Mn) is preferably 5,000 or more, particularly 10,000 or more, and 50,000 or less, particularly 40,000 or less.

  In the recording liquid of the present invention, the content of all the polymers including the polymer (I) and the polymer (I) other than the polymer (I) such as the polymer (II) is usually 0.05% by weight or more, preferably 0. It is 25% by weight or more, more preferably 0.5% by weight or more, and the upper limit is usually 20% by weight or less, preferably 10% by weight or less. Moreover, as a use ratio of the polymer (I) and other polymers, the weight ratio of the polymer (I) and the other polymer may be appropriately selected and determined in the range of 99: 1 to 1:99. In order to effectively exhibit the above-described improvement effect by the polymer (I), specifically, the other polymer is 10 parts by weight or less, particularly 5 parts by weight or less, with respect to 1 part by weight of the total amount of the polymer (I). In particular, the amount is preferably 3 parts by weight or less.

  In addition, polymer fine particles may be added to the recording liquid of the present invention in order to further improve the fixability and abrasion resistance of an image on a recording medium. The polymer fine particles are not particularly limited, but those having an ionic group on the surface and a particle diameter of 10 to 150 nm are preferable.

  The amount of the polymer fine particles used may be appropriately selected and determined within a range not impairing the effects of the present invention. % By weight, more preferably 10 to 50% by weight.

[Method for producing aqueous pigment dispersion and ink composition]
In the method for producing the aqueous pigment dispersion of the present invention containing the polymer (I) described above as the dispersant, the mixing method and the order of addition of (b) pigment, (a) aqueous medium, (c) dispersant and the like are arbitrary. For example, a dispersion process may be performed on a mixture obtained by mixing (a) an aqueous medium, (b) a pigment, and (c) a dispersing agent at once using a general disperser.

  In this dispersion treatment, (a) it is preferable to perform the dispersion treatment using only water as an aqueous medium from the viewpoint of dispersibility and storage stability of the recording liquid.

  As the disperser used for the dispersion treatment, various dispersers that are generally used for pigment dispersion can be used.

  The disperser is not particularly limited, and a paint shaker, ball mill, sand mill, attritor, pearl mill, coball mill, homomixer, homogenizer, wet jet mill, ultrasonic homogenizer, and the like can be used. Glass beads, zirconia beads, alumina beads, magnetic beads, and styrene beads can be used for those using media as a disperser. Among these, a particularly preferable dispersion treatment method is a method in which beads are dispersed with a mill using a medium and then dispersed with an ultrasonic homogenizer.

  A method for obtaining an aqueous pigment dispersion having a preferable dispersed particle diameter is not particularly limited, but the pigment in the dispersion is used to reduce the size of the dispersion media of the disperser and increase the filling rate of the grinding media. Examples thereof include a method of increasing the concentration, extending the treatment time, classifying with a filter or a centrifuge after pulverization, or a combination of these methods. Although not particularly defined, when the dispersion is thickened due to heat generation during dispersion, it is desirable to carry out dispersion treatment while cooling, and conversely, heating reduces the particle size during dispersion. When it is remarkable, it is desirable to perform the dispersion treatment at a high temperature.

  The obtained dispersion is desirably subjected to pressure filtration using a filter or centrifugal separation for the purpose of removing coarse particles as necessary.

  As described above, the recording liquid (ink composition) of the present invention is mixed and dispersed in the same manner by adding a colorant and various additives as necessary to the aqueous pigment dispersion thus prepared. It is prepared by.

  Hereinafter, the present invention will be described more specifically with reference to synthesis examples, examples, and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

In the following examples, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the random copolymers A to P were measured under the following conditions using gel permeation chromatography (GPC).
Column packing: Styrene-divinylbenzene copolymer Solvent: Tetrahydrofuran Flow rate: 0.7ml / min
Temperature: 40 ° C
Calibration was performed using polystyrene.
In addition, this time, it measured using the following apparatuses, detectors, and columns.
Apparatus: Waters 2690 manufactured by Nippon Waters Co., Ltd.
Detector: Waters 2410 manufactured by Nippon Waters Co., Ltd.
Column: Shodex KF-604 / KF-603 / KF-602.5 manufactured by Showa Denko KK

In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the block copolymer X were measured under the following conditions using gel permeation chromatography (GPC).
Column packing material: Polyhydroxymethacrylate Solvent: Water / acetonitrile
(70/30 (v / v),
0.2M Tris HCl buffer, 0.1M KCl included)
Flow rate: 0.7mL / min
Temperature: 40 ° C
Calibration was performed using polyethylene glycol.
In addition, this time, it measured using the following apparatuses, detectors, and columns.
Apparatus: Waters 2695 made by Nippon Waters Co., Ltd.
Detector: Waters 2410 manufactured by Nippon Waters Co., Ltd.
Column used: Shodex OHpak manufactured by Showa Denko KK
SB-G / SB-804HQ / SB-803HQ / SB-802.5HQ

The structures of the obtained random copolymers A to P were confirmed by ¹ H-NMR using d-DMSO (dimethyl sulfoxide) as a solvent, and the composition ratio of the monomer constitutional units was calculated from NMR data.
In the following notation, “co” means “co” of the copolymer, and “b” means “block” of the block polymer.

[Polymer synthesis]
<Synthesis Example 1>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer A) Into a flask with a nitrogen-substituted interior, a nitrogen introduction tube, a stirrer and a thermometer, 2 , 2′-azobis (2,4-dimethylvaleronitrile) 5.6 g, 700 g of methanol as a solvent, 349.9 g of styrene as a monomer, and methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd., In general formula (2), m = 9) 809.8 g and 121.0 g of acrylic acid were charged. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 4 hours. Thereafter, a solution prepared by dissolving 5.6 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 56 g of methanol was added to the reaction system, and the polymerization reaction was further performed for 6 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, 78.4 g of 5N sodium hydroxide aqueous solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude polymer aqueous solution. . After removing impurities from the crude polymer aqueous solution by ultrafiltration, the polymer aqueous solution is concentrated and dried to obtain water-soluble poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer A. It was.

  The random copolymer A had a number average molecular weight (Mn) of 15000, a weight average molecular weight (Mw) of 31,000, and a molecular weight distribution of (Mw / Mn) of 2.1.

The structure of the random copolymer A was confirmed by ¹ H-NMR using d-DMSO (dimethyl sulfoxide) as a solvent. As a result, a styrene structural unit, a methoxypolyethylene glycol acrylate structural unit, and a sodium acrylate structural unit in the random copolymer A were obtained. The composition ratio was 56/21/23 (molar ratio) = 32/56/12 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.57)

<Synthesis Example 2>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer B) Into a flask with a nitrogen-substituted interior, a nitrogen introduction tube, a stirrer and a thermometer, 2 , 2′-azobis (2,4-dimethylvaleronitrile) 1.2 g, 140.8 g of methanol as a solvent, 33.8 g of styrene as a monomer, and methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) ) 126.2 g and 4.7 g of acrylic acid were charged. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 4 hours. Thereafter, a solution prepared by dissolving 0.6 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 6 g of methanol was added to the reaction system, and a polymerization reaction was further performed for 4 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, 9.2 g of 5N aqueous sodium hydroxide solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude aqueous polymer solution. . After removing impurities from the crude polymer aqueous solution by ultrafiltration, the polymer aqueous solution is concentrated and dried to obtain water-soluble poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer B. It was.

  The random copolymer B had a number average molecular weight (Mn) of 17000, a weight average molecular weight (Mw) of 33,000, and a molecular weight distribution of (Mw / Mn) of 1.9.

When the structure of the random copolymer B was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, the methoxypolyethylene glycol acrylate structural unit, and the sodium acrylate structural unit in the random copolymer B was 60/33/7 (molar ratio) = 27/70/3 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.39)

<Synthesis Example 3>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer C) Into a flask equipped with a nitrogen-substituted condenser, a nitrogen introduction tube, a stirrer and a thermometer, 2 , 2'-azobis (2,4-dimethylvaleronitrile) 3.7g, methanol 424.2g, styrene 101.5g as monomer, methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 378.7 g and 14.2 g of acrylic acid were charged. The bath temperature was raised from room temperature to 70 ° C. over 50 minutes, and a polymerization reaction was carried out at 70 ° C. for 4 hours. Thereafter, a solution prepared by dissolving 1.7 g of 2,2′-azobis (2,4-dimethylvaleronitrile), which is a polymerization initiator, in 16.5 g of methanol was added to the reaction system, and the polymerization reaction was further performed for 6 hours. .

  After completion of the reaction, the reaction solution was cooled to room temperature, 32.7 g of 5N sodium hydroxide aqueous solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude polymer aqueous solution. . After removing impurities from the crude polymer aqueous solution by ultrafiltration, the polymer aqueous solution is concentrated and dried to obtain water-soluble poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer C. It was.

  The random copolymer C had a number average molecular weight (Mn) of 18,600, a weight average molecular weight (Mw) of 33,000, and a molecular weight distribution of (Mw / Mn) of 1.8.

When the structure of the random copolymer C was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, the methoxypolyethylene glycol acrylate structural unit, and the sodium acrylate structural unit in the random copolymer C was 60/35/5 (molar ratio) = 26/72/2 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.36)

<Synthesis Example 4>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer D) Into a flask with a nitrogen-substituted interior, a nitrogen introduction tube, a stirrer and a thermometer, 2 2,2′-azobis (2,4-dimethylvaleronitrile) 2.57 g, methanol 278 g, styrene 41.28 g, methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 153. 01 g and 5.71 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 5 hours. Thereafter, a solution prepared by dissolving 1.07 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 10 g of methanol was added to the reaction system, and a polymerization reaction was further performed for 3 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, 13.18 g of 5N sodium hydroxide aqueous solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude polymer aqueous solution. After removing impurities from the crude aqueous polymer solution by ultrafiltration, the aqueous polymer solution was concentrated and dried to obtain poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer D.

  The random copolymer D had a number average molecular weight (Mn) of 12,800, a weight average molecular weight (Mw) of 22,100, and a molecular weight distribution of (Mw / Mn) of 1.7.

When the structure of the random copolymer D was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, methoxypolyethylene glycol acrylate structural unit, and sodium acrylate structural unit in the random copolymer D was 54/29/17 (molar ratio) = 28/69/3 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.41)

<Synthesis Example 5>
Synthesis of poly (styrene-co-N-2-hydroxyethylacrylamide-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (random copolymer E) Condenser with nitrogen substitution inside, nitrogen inlet tube, stirrer and thermometer A flask with a mixture was charged with 8.98 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator, 1208 g of methanol as a solvent, 191.64 g of styrene as a monomer, and 60.46 g of 2-hydroxyethylacrylamide. , 634.24 g of methoxy polyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) and 113.65 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 50 minutes, and a polymerization reaction was carried out at 70 ° C. for 4 hours. Thereafter, a solution prepared by dissolving 3.74 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 31.68 g of methanol was added to the reaction system, and the polymerization reaction was further performed for 6 hours. .

  After completion of the reaction, the reaction solution was cooled to room temperature, and 261.81 g of 5N sodium hydroxide aqueous solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude polymer aqueous solution. . After removing impurities from the crude polymer aqueous solution by ultrafiltration, the polymer aqueous solution is concentrated and dried to poly (styrene-co-2-hydroxyethylacrylamide-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): Random copolymer E was obtained.

  The random copolymer E had a number average molecular weight (Mn) of 15400, a weight average molecular weight (Mw) of 25500, and a molecular weight distribution of (Mw / Mn) of 1.7.

The structure of the random copolymer E was confirmed by ¹ H-NMR using d-DMSO as a solvent. As a result, the styrene structural unit, 2-hydroxyethylacrylamide structural unit, methoxypolyethylene glycol acrylate structural unit, acrylic The composition ratio of the sodium acid structural unit was 38/8/18/36 (molar ratio) = 23/6/51/20 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.45)

<Synthesis Example 6>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer F) Into a flask equipped with a nitrogen-substituted interior, a nitrogen introduction tube, a stirrer and a thermometer, 2 , 2'-azobis (2,4-dimethylvaleronitrile) 3.9 g, methanol 537.3 g as solvent, styrene 139.1 g as monomer, methoxypolyethylene glycol acrylate (AM-230G, Shin-Nakamura Chemical Co., Ltd.) Manufactured, and the above general formula (2) was charged with m = 23) 353.4 g and acrylic acid 58.8 g. The bath temperature was raised from room temperature to 70 ° C. over 50 minutes, and a polymerization reaction was carried out at 70 ° C. for 4 hours. Thereafter, a solution obtained by dissolving 1.8 g of 2,2′-azobis (2,4-dimethylvaleronitrile), which is a polymerization initiator, in 17.9 g of methanol was added to the reaction system, and a polymerization reaction was further performed for 6 hours. .

  After completion of the reaction, the reaction solution was cooled to room temperature, and after adding 135.9 g of 5N aqueous sodium hydroxide solution with stirring, a crude polymer aqueous solution was obtained by adding distilled water while removing methanol with an evaporator. . After removing impurities from the crude polymer aqueous solution by ultrafiltration, the polymer aqueous solution is concentrated and dried to obtain water-soluble poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer F. It was.

  This polymer F had a number average molecular weight (Mn) of 16,400, a weight average molecular weight (Mw) of 26800, and a molecular weight distribution of (Mw / Mn) of 1.6.

When the structure of the random copolymer F was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, methoxypolyethylene glycol acrylate structural unit, and sodium acrylate structural unit in the random copolymer F was 54/13/33 (molar ratio) = 24/62/14 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.39)

<Synthesis Example 7>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer G) Into a flask with a nitrogen-substituted condenser, a nitrogen introduction tube, a stirrer and a thermometer, 2 , 2′-azobis (2,4-dimethylvaleronitrile) 7.70 g, 972.5 g of methanol as a solvent, 200.2 g of styrene as a monomer, methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 695.9 g and 103.9 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 50 minutes, and a polymerization reaction was carried out at 70 ° C. for 4 hours. Thereafter, a solution prepared by dissolving 3.2 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 15 g of methanol was added to the reaction system, and a polymerization reaction was further performed for 6 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, 239.4 g of 5N sodium hydroxide aqueous solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude polymer aqueous solution. After removing impurities from the crude aqueous polymer solution by ultrafiltration membrane treatment, the aqueous polymer solution was concentrated and dried to obtain poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random polymer G.

  The random copolymer G had a number average molecular weight (Mn) of 18,500, a weight average molecular weight (Mw) of 31,400, and a molecular weight distribution of (Mw / Mn) of 1.7.

The structure of the random copolymer G was confirmed by ¹ H-NMR using d-DMSO as a solvent. The composition ratio of styrene units, methoxypolyethylene glycol acrylate units, and sodium acrylate units in the random copolymer was 39/22. / 39 (molar ratio) = 23/57/20 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene chain monomer composition ratio (weight ratio) = 0.38)

<Synthesis Example 8>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer H) Into a flask equipped with a nitrogen-substituted interior, a nitrogen introduction tube, a stirrer and a thermometer, 2 , 2′-azobis (2,4-dimethylvaleronitrile) 2.6 g, methanol 278.0 g as a solvent, styrene 41.3 g as a monomer, methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 153.0 g and 5.7 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 5 hours. Thereafter, a solution obtained by dissolving 1.1 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 9 g of methanol was added to the reaction system, and a polymerization reaction was further performed for 3 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, 13.2 g of 5N aqueous sodium hydroxide solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude aqueous polymer solution. After removing impurities from the crude aqueous polymer solution by ultrafiltration, the aqueous polymer solution was concentrated and dried to obtain poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer H.

  This random polymer H had a number average molecular weight (Mn) of 11,400, a weight average molecular weight (Mw) of 19,600, and a molecular weight distribution of (Mw / Mn) of 1.7.

The structure of the random copolymer H was confirmed by ¹ H-NMR using d-DMSO as a solvent. The composition ratio of the styrene structural unit, methoxypolyethylene glycol acrylate structural unit, and sodium acrylate structural unit in the random copolymer H was 52/33/15 (molar ratio) = 24/70/6 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene chain-containing monomer structural unit (weight ratio) = 0.34)

<Synthesis Example 9>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer I) To a flask equipped with a nitrogen-substituted condenser, a nitrogen introducing tube, a stirrer and a thermometer, 2 , 2'-azobis (2,4-dimethylvaleronitrile) 15.6 g, 1722.5 g of methanol as a solvent, 324.9 g of styrene as a monomer, methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 751.9 g and 112.3 g of acrylic acid were charged. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 4 hours. Thereafter, a solution prepared by dissolving 6.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 65 g of methanol was added to the reaction system, and a polymerization reaction was further performed for 6 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, 258.7 g of 5N sodium hydroxide aqueous solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude limer aqueous solution. . After removing impurities from the crude polymer aqueous solution by ultrafiltration, the polymer aqueous solution is concentrated and dried to obtain water-soluble poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer I. It was.

  The random copolymer I had a number average molecular weight (Mn) of 8000, a weight average molecular weight (Mw) of 18000, and a molecular weight distribution of (Mw / Mn) of 2.3.

When the structure of the random copolymer I was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, the methoxypolyethylene glycol acrylate structural unit, and the sodium acrylate structural unit in the random copolymer I was 52/19/29 (molar ratio) = 31/53/16 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.58)

<Synthesis Example 10>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer J) Into a flask with a nitrogen-substituted interior, a nitrogen introduction tube, a stirrer and a thermometer, 2 , 2′-azobis (2,4-dimethylvaleronitrile) 2.6 g, methanol 278 g as a solvent, styrene 41.3 g as a monomer, methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 153. 0 g and 5.7 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 5 hours. Thereafter, a solution obtained by dissolving 1.1 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 9 g of methanol was added to the reaction system, and a polymerization reaction was further performed for 3 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, 13.2 g of 5N aqueous sodium hydroxide solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude aqueous polymer solution. After removing impurities from the crude polymer aqueous solution by ultrafiltration, the polymer aqueous solution was concentrated and dried to obtain poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer J.

  The random copolymer J had a number average molecular weight (Mn) of 12,200, a weight average molecular weight (Mw) of 20,800, and a molecular weight distribution of (Mw / Mn) of 1.7.

When the structure of the random copolymer J was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, the methoxypolyethylene glycol acrylate structural unit, and the sodium acrylate structural unit in the random copolymer J was 54/33/13 (molar ratio) = 25/70/5 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.36)

<Synthesis Example 11>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Copolymer K) Into a flask equipped with a nitrogen-substituted condenser, a nitrogen introducing tube, a stirrer and a thermometer, 2 , 2′-azobis (2,4-dimethylvaleronitrile) 3.9 g, 347 g of methanol as a solvent, 69.2 g of styrene as a monomer, methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 4 g and 7.4 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 5 hours. Thereafter, a solution obtained by dissolving 1.6 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 16 g of methanol was added to the reaction system, and a polymerization reaction was further performed for 3 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, 17.0 g of 5N sodium hydroxide aqueous solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude polymer aqueous solution. . After removing impurities from the crude aqueous polymer solution by ultrafiltration, the aqueous polymer solution was concentrated and dried to obtain poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer K.

  This random copolymer K had a number average molecular weight (Mn) of 10,000, a weight average molecular weight (Mw) of 16000, and a molecular weight distribution of (Mw / Mn) of 1.6.

When the structure of the random copolymer K was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, the methoxypolyethylene glycol acrylate structural unit, and the sodium acrylate structural unit in the random copolymer K was 61/19/20 (molar ratio) = 36/53/11 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene-containing monomer structural unit (weight ratio) = 0.68)

<Synthesis Example 12>
Synthesis of poly (sodium acrylate-co-n-butyl acrylate-co-styrene) (Random Copolymer L) Into a flask equipped with a nitrogen-substituted condenser, a nitrogen introducing tube, a stirrer and a thermometer, 2 , 2′-azobis (2,4-dimethylvaleronitrile) 30 g, 3500.0 g of tetrahydrofuran as a solvent, 600.0 g of acrylic acid, 600.0 g of n-butyl acrylate, and 400.0 g of styrene as monomers. The bath temperature was raised from room temperature to 70 ° C. over 1 hour, and the polymerization reaction was carried out at 70 ° C. for 8 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, neutralized with a sodium hydroxide / methanol solution, and precipitated in isopropyl alcohol. The precipitate was filtered and vacuum dried to obtain a mixture of poly (sodium acrylate-co-n-butyl acrylate-co-styrene): random copolymer L and sodium acrylate.

  The random copolymer L had a number average molecular weight (Mn) of 11,000, a weight average molecular weight (Mw) of 18000, and a molecular weight distribution (Mw / Mn) of 1.6.

  After dissolving 30.0 g of the random copolymer L and sodium acrylate in 970.0 g of water, sodium acrylate was removed by ultrafiltration. After removing sodium acrylate, the polymer aqueous solution was concentrated and dried to obtain the random copolymer L.

  When the structure of the random copolymer L was confirmed by H-NMR using heavy water as a solvent, the composition ratio of the sodium acrylate structural unit, the n-butyl acrylate structural unit, and the styrene structural unit in the random copolymer L was 47 / It was 21/32 (molar ratio) = 46/25/29 (weight% ratio).

<Synthesis Example 13>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol methacrylate-co-sodium acrylate) (Random Copolymer M) In a flask equipped with a nitrogen-substituted condenser, a nitrogen introduction tube, a stirrer and a thermometer, 2 was added as a polymerization initiator. , 2′-azobis (2,4-dimethylvaleronitrile) 5.6 g, methanol 232.0 g as solvent, styrene 67.2 g as monomer, methoxypolyethylene glycol methacrylate (PME-200, manufactured by NOF Corporation) In the general formula (2), m = 4) 93.3 g and 39.8 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 5 hours. Thereafter, a solution prepared by dissolving 2.6 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 15.0 g of methanol was added to the reaction system, and the polymerization reaction was further performed for 5 hours. .

  After completion of the reaction, the reaction solution was cooled to room temperature, 82.0 g of 5N sodium hydroxide aqueous solution was added with stirring, and then distilled water was added while removing methanol with an evaporator to obtain a crude polymer aqueous solution. . After removing impurities from the crude aqueous polymer solution by ultrafiltration, the aqueous polymer solution was concentrated and dried to obtain poly (styrene-co-methoxypolyethyleneglycol methacrylate-co-sodium acrylate): random copolymer M.

  The random copolymer M had a number average molecular weight (Mn) of 4800, a weight average molecular weight (Mw) of 14100, and a molecular weight distribution of (Mw / Mn) of 2.9.

When the structure of this random copolymer M was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, methoxypolyethylene glycol methacrylate structural unit, and sodium acrylate structural unit in the random copolymer M was 44/20/36 (molar ratio) = 34/41/25 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit (weight ratio) = 0.83)

<Synthesis Example 14>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate) (Random Copolymer N) 2,2′-Azobis (as a polymerization initiator) was placed in a condenser equipped with nitrogen inside, a nitrogen inlet tube, a stirrer and a thermometer-equipped flask. 2,4-dimethylvaleronitrile) 2.2 g, methanol 210.7 g, styrene 60.3 g as a monomer, and methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 140.1 g Was placed in the flask. The bath temperature was raised from room temperature to 70 ° C. over 30 minutes, and a polymerization reaction was carried out at 70 ° C. for 4 hours. Thereafter, a solution prepared by dissolving 0.9 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator in 9.2 g of methanol was added to the reaction system, and the polymerization reaction was further performed for 4 hours. .

  After completion of the reaction, the reaction solution was cooled to room temperature, and distilled water was added while removing methanol with an evaporator to obtain a crude polymer aqueous solution. After removing impurities from the crude polymer aqueous solution by ultrafiltration, the polymer aqueous solution was concentrated and dried to obtain poly (styrene-co-methoxypolyethylene glycol acrylate): random copolymer N.

  The random copolymer N had a number average molecular weight (Mn) of 12000, a weight average molecular weight (Mw) of 21,400, and a molecular weight distribution of (Mw / Mn) of 1.8.

When the structure of the random copolymer N was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit and the methoxypolyethylene glycol methacrylate structural unit in the random copolymer N was 70/30 (moles). Ratio) = 33/67 (% by weight). (Hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit (weight ratio) = 0.49)

<Synthesis Example 15>
Synthesis of poly (styrene-co-methoxypolyethyleneglycol acrylate-co-sodium acrylate) (Random Polymer O) Into a condenser equipped with nitrogen, a nitrogen inlet tube, a stirrer, and a thermometer-equipped flask as a polymerization initiator , 2'-azobiz (2,4-dimethylvaleronitrile) 0.86g, methanol 129g as a solvent, styrene 21.95g as a monomer, methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.) 25 g and 96.84 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 50 minutes, and a polymerization reaction was carried out at 70 ° C. for 2 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, and after adding 295.52 g of 5N aqueous sodium hydroxide solution with stirring, distilled water was added to obtain a crude polymer aqueous solution. After removing impurities from the crude polymer aqueous solution by ultrafiltration membrane treatment, the polymer aqueous solution was concentrated and dried to obtain poly (styrene-co-methoxypolyethylene glycol acrylate-co-sodium acrylate): random copolymer O.

  The random copolymer O had a number average molecular weight (Mn) of 42,000, a weight average molecular weight (Mw) of 113700, and a molecular weight distribution of (Mw / Mn) of 2.70.

When the structure of the random copolymer O was confirmed by ¹ H-NMR using d-DMSO as a solvent, the composition ratio of the styrene structural unit, the methoxypolyethylene glycol methacrylate structural unit, and the sodium acrylate structural unit in the random copolymer O was 13/4/83 (molar ratio) = 13/17/70 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit (weight ratio) = 0.76)

<Synthesis Example 16>
Synthesis of poly (styrene-co-N-2-hydroxyethyl (meth) acrylamide-co-methoxypolyethylene glycol acrylate-co-sodium acrylate) (random polymer P) Condenser with nitrogen substitution inside, nitrogen introduction tube, stirrer In addition, 0.84 g of 2,2′-azobiz (2,4-dimethylvaleronitrile) as a polymerization initiator was charged into a flask equipped with a thermometer, 129 g of methanol as a solvent, 7.89 g of styrene as a monomer, 2-hydroxyethylacrylamide 14.60 g, 60.64 g of methoxypolyethylene glycol acrylate (Light Acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.), and 67.01 g of acrylic acid were charged into the flask. The bath temperature was raised from room temperature to 70 ° C. over 50 minutes, and a polymerization reaction was carried out at 70 ° C. for 2 hours.

  After completion of the reaction, the reaction solution was cooled to room temperature, and after adding 215.64 g of 5N aqueous sodium hydroxide solution with stirring, distilled water was added while removing methanol with an evaporator to obtain a crude aqueous polymer solution. . After removing impurities from the crude polymer aqueous solution by ultrafiltration membrane treatment, the polymer aqueous solution is concentrated and dried, and then poly (styrene-co-N-2-hydroxyethyl (meth) acrylamide-co-methoxypolyethylene glycol acrylate-co -Sodium acrylate): Random polymer P was obtained.

  The random copolymer P had a number average molecular weight (Mn) of 18,300, a weight average molecular weight (Mw) of 77900, and a molecular weight distribution of (Mw / Mn) of 4.3.

The structure of the random copolymer P was confirmed by ¹ H-NMR using d-DMSO as a solvent. As a result, a styrene structural unit, a 2-hydroxyethylacrylamide structural unit, a methoxypolyethylene glycol acrylate structural unit, an acrylic in the random copolymer P were obtained. The composition ratio of the sodium acid structural unit was 7/5/11/77 (molar ratio) = 5/4/38/53 (weight% ratio). (Hydrophobic monomer structural unit / oxyalkylene chain monomer structural unit (weight ratio) = 0.13)

<Synthesis Example 17>
Synthesis of polyvinyl alcohol-b-poly (sodium acrylate-co-methyl acrylate-co-sodium methacrylate-co-benzyl methacrylate-co-styrene) (block copolymer X) Capacitor with nitrogen substitution inside, nitrogen introduction tube Into a flask equipped with a stirrer and a thermometer, 3587 g of vinyl acetate, 1907 g of chloroform as a chain transfer agent and a solvent were charged, and the temperature was raised to 70 ° C. over 1 hour. Next, a polymerization initiator solution in which 0.3 g of azobis (2-methylbutyronitrile) as a polymerization initiator was dissolved in 534 g of chloroform was dropped over 6 hours. Thereafter, a polymerization initiator solution in which 0.5 g of azobis (2-methylbutyronitrile) as a polymerization initiator was dissolved in 444.5 g of chloroform was dropped over 5 hours. After dropwise addition of the polymerization initiator solution, the mixture was heated and polymerized for 10 hours under reflux conditions. After completion of the reaction, 0.01 N sodium hydroxide / methanol solution was continuously added dropwise to the reaction solution, and unreacted vinyl acetate and chloroform were distilled off under reduced pressure at an internal temperature of 40 ° C. to obtain a polyvinyl acetate methanol solution (polymer concentration). 74% by weight). This polyvinyl acetate had a number average molecular weight (Mn) of 3500 and a molecular weight distribution (Mw / Mn) of 2.4.

The terminal structure of the polyvinyl acetate was —CCl ₃ . This is because, in ¹ H-NMR (solvent CDCl ₃ ), a peak of a methylene group (peak of chemical shift δ = 2.8 to 3.2) was observed adjacent to the end of the polyvinyl acetate, Based on the fact that the number average molecular weight (3500) calculated by using -CCl ₃ as the terminal structure and the number average molecular weight determined from GPC coincide with each other, a group in which one end is quantitatively halogen-substituted (-CCl ₃ ) It was confirmed that the polyvinyl acetate having the above could be synthesized.

  Next, a condenser with a nitrogen-substituted interior, a nitrogen inlet tube, a stirrer and a thermometer-equipped flask, 17 g of methanol as a solvent and 1048.5 g of isopropyl alcohol, 2623 g of methyl acrylate, 2142 g of benzyl methacrylate, and styrene as monomers 63.5 g and the above polyvinyl acetate methanol solution 1353 g as a macroinitiator were charged, and the temperature was raised from room temperature to 60 ° C. over 1 hour. When the internal temperature reached 60 ° C., a catalyst solution in which 0.6 g of cuprous bromide as a catalyst and 12.0 g of tris (2-dimethylamino) ethylamine as a ligand were dissolved in 30 g of methanol was added. After addition of the catalyst solution, the mixture was heated and polymerized for 30 hours under reflux conditions.

  The number average molecular weight (Mn) of the obtained polymer increased with the lapse of the polymerization reaction time.

  Table 1 shows the molar ratio of each monomer of methyl acrylate (MA), benzyl methacrylate (BzMA), and styrene (St) in the polymer calculated from the amount of monomer consumption in the polymerization solution, obtained from gas chromatography. .

  As is clear from Table 1, the composition of the block copolymer linked with polyvinyl acetate changes as the number average molecular weight increases, and the monomer composition in the block copolymer changes toward the end (gradient). ) Polyvinyl acetate-b-poly (methyl acrylate-co-benzyl methacrylate-co-styrene) was confirmed. The polymer had a number average molecular weight of 16,300 and a molecular weight distribution (Mw / Mn) of 1.63. In this polyvinyl acetate block copolymer, the linking group connecting the polyvinyl acetate block and the other block is a dichloromethylene group.

  Next, in a reaction vessel equipped with a condenser, a stirrer and a thermometer, the above polymerized solution 502 g was dissolved in a mixed solvent of 276 g of methanol, 552 g of tetrahydrofuran and 138 g of water, and then the temperature was raised to 60 ° C. and 728 g of 5N sodium hydroxide aqueous solution. In addition, the reaction was carried out at 65 ° C. for 7 hours. After completion of the reaction, 550 g of tetrahydrofuran (THF) and 140 g of water were added to the polymer mass obtained by removing the supernatant and suspended, and then 280 g of methanol was added to precipitate the polymer. The supernatant was removed again, 300 g of water was added, neutralized with acetic acid, the solution was heated to 90 ° C., and the remaining THF and methanol were distilled off to obtain an aqueous polymer solution. Thereafter, impurities were removed from the aqueous polymer solution using an ultrafiltration membrane (ACP-1050, manufactured by Asahi Kasei Corporation). Polyvinyl alcohol-b-poly (sodium acrylate-co-methyl acrylate-co-methacrylic acid) in which the copolymer linked to the polyvinyl alcohol block is a gradient copolymer by concentrating and drying the polymer aqueous solution after ultrafiltration Sodium-co-benzyl methacrylate-co-styrene) (block copolymer X) was obtained.

  In this polyvinyl alcohol block copolymer X, the linking group linking the polyvinyl alcohol block and the other block is one in which some or all of the chlorine atoms in the linking group (dichloromethylene group) are replaced with hydrogen atoms. It is.

The structure of this block copolymer X was confirmed by ¹ H-NMR using heavy water as a solvent. The composition ratio of the vinyl alcohol structural unit, sodium acrylate structural unit, methyl acrylate structural unit, sodium methacrylate structural unit, benzyl methacrylate structural unit, and styrene structural unit in the block copolymer X determined by ¹ H-NMR is as follows: 25: 26: 21: 2: 21: 5 (molar ratio). The number average molecular weight (Mn) of the polymer was 14,000, and the molecular weight distribution (Mw / Mn) was 1.59.

[Examples and Comparative Examples]
Below, polymers A to G which are the polymers (I) according to the present invention obtained in Synthesis Examples 1 to 7, or polymers H to P other than the polymer (I) obtained in Synthesis Examples 8 to 16, and The manufacture example of the aqueous pigment dispersion using the block copolymer X obtained in Synthesis Example 17 and the evaluation results of the ink using the same are shown.

<Example 1>
Pigment Blue-15: 3 (manufactured by Dainichi Seika Kogyo Co., Ltd .; powder; solid content 100 wt%) 28.0 g, random copolymer A aqueous solution (random copolymer A concentration 10.2 wt%) 109.4 g, block copolymer X 14.4 g of an aqueous solution (block copolymer X concentration: 9.8% by weight) and 128.3 g of deionized water are mixed and preliminarily maintained for 1 hour with CLEARMIX (MTECHNIQUE; CLM-0.8S), which is a rotary disperser. After dispersion, 0.3 mmφ zirconia beads were used as a medium for dispersion for 8 hours at 25 ° C. using a self-made bead mill. After removing the beads, the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 180 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion A.

This pigment dispersion A was used to make an ink according to the following formulation.
(Ink composition)
Pigment dispersion A 5.63 g
Deionized water 6.60g
2-pyrrolidone 0.77g
Glycerin 1.13g
1,6-hexanediol 0.74 g
Olfin E1010 (Surfactant manufactured by Air Products) 0.15 g

  The above components were mixed, stirred for 15 minutes, and subjected to ultrasonic treatment for 30 minutes to obtain a recording liquid (ink composition) of Example 1.

  With respect to the obtained recording liquid of Example 1, the following characteristics (1) to (4) were evaluated by the following test methods. The results are shown in Table 3.

  In addition, an inkjet recording system printer (BJ-S700 printer manufactured by Canon Inc.) was used as the printer, and a commercially available glossy paper (Glossy Paper SP-101 manufactured by Canon Inc.) was used as the printing paper.

(1) Stability of recording liquid For the recording liquid, the dispersed particle diameter and viscosity of the pigment immediately after preparation and the dispersed particle diameter and viscosity of the pigment after being held at 70 ° C. for 15 hours were measured. The smaller the increase in particle size and viscosity after holding, the more stable it is.

  The dispersed particle size of the pigment was measured by diluting the recording liquid 10,000 times with deionized water and using a dilution probe with Otsuka Electronics Co., Ltd. FPAR-1000, and the average particle size was calculated by the Cumulant method. . The viscosity was measured using a rheometer (REOLOGICA AB Instruments; VAR-100; cone 1 ° / 55φ), and the value at a shear rate of 100 / sec was read.

(2) Print clarity (glossiness)
The gloss and haze of the glossy paper printed with the recording liquid was dried for 1 day at room temperature, and the gloss and haze were measured. Gross measurement and haze measurement were performed using a Haze-Gloss meter (Cat. No. 4601 manufactured by BYK Gardner), and a measured value of 20 ° was adopted as the gloss value. In general, when the gloss is high, the haze tends to be high. Therefore, it is difficult to obtain the superiority or inferiority of the glossiness only by comparing the respective values. Therefore, the haze / gross value was compared as the sharpness. The smaller this value is, the lower the clearness, that is, the lower the light irregular reflection on the image surface.

(3) Dischargeability of recording liquid After the recording liquid was filled in the cartridge, printing was performed on 50 glossy papers in a plain paper mode with a printer, and visually observed for blurring, etc., and evaluated according to the following criteria.
○: No fading △: Fading during printing ×: Image cannot be printed neatly

(4) Scratch resistance of printed matter The printed surface of the printed matter obtained by the evaluation in (2) was rubbed with a finger, and the presence or absence of peeling of the printed surface was visually observed and evaluated according to the following criteria.
○: There is no peeling of the printed surface, and the scratch resistance is excellent.
Δ: There is some peeling of the printed surface.
X: The printed surface peels off, causing a problem in practical use, and the scratch resistance is poor.

<Example 2>
Pigment Blue-15: 3 (manufactured by Dainichi Seika Kogyo Co., Ltd .; powder; solid content: 100% by weight) 28.0 g, random copolymer B aqueous solution (random copolymer B concentration 24.7% by weight), 45.3 g, block copolymer X 14.3 g of an aqueous solution (block copolymer X concentration: 9.8% by weight) and 192.3 g of deionized water were mixed, and after pre-dispersing for 1 hour with CLEARMIX (MTECHNIQUE; CLM-0.8S), 0.3 mmφ A zirconia bead was used as a medium for dispersion for 8 hours at 25 ° C. using a self-made bead mill. After removing the beads, a pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 180 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion B.

  Using this pigment dispersion B instead of the pigment dispersion A, a recording liquid was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 3.

<Example 3>
Pigment Yellow 155 (Clariant INK JET YELLOW 4G VP2532; powder; solid content 100.0% by weight) 28.0 g, random copolymer A aqueous solution (random copolymer A concentration 10.2% by weight) 54.7 g, block copolymer X aqueous solution (Block copolymer X concentration: 9.8 wt%) 43.0 g and deionized water 154.3 g were mixed, pre-dispersed for 10 minutes with a homomixer, and then at 25 ° C. using a bead mill with 0.3 mmφ zirconia beads as media. And after removing the beads, the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 120 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion C.

  Using this pigment dispersion C instead of the pigment dispersion A, a recording liquid was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 3.

<Example 4>
Pigment Yellow 155 (INK JET YELLOW 4G VP2532 manufactured by Clariant, powder; solid content 100.0 wt%) 28.0 g, random copolymer B aqueous solution (random copolymer B concentration 24.7 wt%) 22.7 g, block copolymer X aqueous solution (Block copolymer X concentration 9.8% by weight) 43.0 g and deionized water 186.3 g were mixed, pre-dispersed for 10 minutes with a homomixer, and then at 25 ° C. using a bead mill with 0.3 mmφ zirconia beads as media. And after removing the beads, the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 120 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion D.

  Using this pigment dispersion D instead of pigment dispersion A, a recording liquid was prepared in the same manner as in Example 1, and evaluated in the same manner. The results are shown in Table 3.

<Example 5>
Carbon black (Mitsubishi Chemical Corporation: # 990; powder; solid content 100 wt%) 28.0 g, random copolymer A aqueous solution (random copolymer A concentration 10.1 wt%) 110.7 g, and deionized water 141.3 g Were mixed for 8 hours at 25 ° C. using a self-made bead mill with 0.5 mmφ zirconia beads as media, and after removing the beads, a pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 90 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion E.

The pigment dispersion E was used to make an ink according to the following formulation.
(Ink composition)
Pigment dispersion E 5.53 g
Deionized water 6.00 g
2-pyrrolidone 0.33g
Glycerin 0.86g
Triethylene glycol 0.72g
Olfin E1010 (Surfactant manufactured by Air Products) 0.15 g
1.32 g ethylene urea

  The above components were mixed, stirred for 15 minutes, and subjected to ultrasonic treatment for 30 minutes to obtain a recording liquid (ink composition) of Example 5.

  This recording liquid was evaluated in the same manner as in Example 1. The results are shown in Table 3.

<Example 6>
Firing product carbon black (# 2300B (manufactured by Mitsubishi Chemical Corporation) at 1200 ° C. for 1 month in a nitrogen atmosphere; powder; solid content: 100 wt%) 28.0 g, random copolymer C aqueous solution (random copolymer C concentration 18) 3 wt%) 61.2 g, block copolymer X aqueous solution (block copolymer X concentration 10.0 wt%) 14.0 g, and 176.8 g of deionized water were mixed, and 0.3 mmφ zirconia beads were used as media Using a bead mill, dispersion was carried out at 60 ° C. for 7 hours and further at 40 ° C. for 1 hour to remove the beads. Then, the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 120 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho, US-600T; used chip 36 mmφ) to obtain pigment dispersion F.

  Using this pigment dispersion F instead of pigment dispersion E, a recording liquid was prepared in the same manner as in Example 5 and evaluated in the same manner. The results are shown in Table 3.

<Example 7>
Firing product carbon black (# 2300B (manufactured by Mitsubishi Chemical Corporation) in a nitrogen atmosphere at 1200 ° C. for 1 month; powder; solid content 100% by weight) 28.0 g, random copolymer D aqueous solution (random copolymer D concentration 13) .3 wt%) 84.2 g, block copolymer X aqueous solution (block copolymer X concentration 10.0 wt%) 14.0 g, and deionized water 153.8 g were mixed, and the zirconia beads of 0.3 mmφ were used as media Using a bead mill, dispersion was carried out at 60 ° C. for 7 hours and further at 40 ° C. for 1 hour to remove the beads. Then, the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 90 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; chip used: 36 mmφ) to obtain pigment dispersion G.

  Using this pigment dispersion G instead of pigment dispersion E, a recording liquid was prepared in the same manner as in Example 5 and evaluated in the same manner. The results are shown in Table 3.

<Example 8>
Firing product carbon black (# 2300B (manufactured by Mitsubishi Chemical Corporation) under nitrogen atmosphere at 1200 ° C. for 1 month; powder; solid content 100% by weight) 28.0 g, random copolymer E aqueous solution (random copolymer E concentration 13) 8 wt.%) 81.3 g, block copolymer X aqueous solution (block copolymer X concentration 15.6 wt.%) 9.0 g, and deionized water 161.7 g were mixed, and Claremix (manufactured by MTECHNIQUE; CLM-0. 8S), pre-dispersed for 1 hour, 0.3mmφ zirconia beads as a medium, dispersed using a bead mill for 7 hours at 60 ° C and 1 hour at 40 ° C. After removing the beads, the pigment concentration was adjusted to 8% by weight. To obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 120 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho, US-600T; used chip 36 mmφ) to obtain pigment dispersion H.

  Using this pigment dispersion H instead of the pigment dispersion E, a recording liquid was prepared in the same manner as in Example 5 and evaluated in the same manner. The results are shown in Table 3.

<Example 9>
Firing product carbon black (# 2300B (manufactured by Mitsubishi Chemical Corporation) in a nitrogen atmosphere at 1200 ° C. for 1 month; powder; solid content: 100% by weight) 28.0 g, random copolymer F aqueous solution (random copolymer F concentration 17) 0.06%), block copolymer X aqueous solution (block copolymer X concentration 11.6% by weight) 12.1 g, and 173.9 g of deionized water were mixed, and Claremix (manufactured by MTECHNIQUE; CLM-0. 8S), pre-dispersed for 1 hour, 0.3mmφ zirconia beads as a medium, dispersed at 70 ° C for 7 hours and 40 ° C for 1 hour using a bead mill. After removing the beads, the pigment concentration was adjusted to 8% by weight. To obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed with an ultrasonic homogenizer (Nippon Seiki Seisakusho, US-600T; used chip 36 mmφ) for 120 minutes to obtain pigment dispersion I.

  Using this pigment dispersion I instead of pigment dispersion E, a recording liquid was prepared in the same manner as in Example 5 and evaluated in the same manner. The results are shown in Table 3.

<Example 10>
Baked product carbon black (# 2300B (manufactured by Mitsubishi Chemical Corporation) at 1200 ° C. for 1 month in a nitrogen atmosphere; powder; solid content 100% by weight) 28.0 g, random copolymer G aqueous solution (random copolymer G concentration 16) 0.0 wt.%) 70.0 g and deionized water 182.0 g were mixed, pre-dispersed with CLEARMIX (MTECHNIQUE; CLM-0.8S) for 1 hour, and then self-made with 0.3 mmφ zirconia beads as media Was used for dispersion for 8 hours at 60 ° C., and the beads were removed, and then the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 120 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion J.

  An ink was prepared in the same manner as in Example 5 using this pigment dispersion J instead of the pigment dispersion E, and evaluated in the same manner. The results are shown in Table 3.

<Comparative Example 1>
Pigment Blue-15: 3 (manufactured by Dainichi Seika Kogyo Co., Ltd .; powder; solid content 100 wt%) 28.0 g, random copolymer H aqueous solution (random copolymer H concentration 15.6 wt%) 71.8 g, block copolymer X 14.1 g of an aqueous solution (block copolymer X concentration 10.0 wt%) and 166.3 g of deionized water were mixed, and after pre-dispersing for 1 hour with CLEARMIX (MTECHNIQUE; CLM-0.8S), 0.3 mmφ A zirconia bead was used as a medium for dispersion for 8 hours at 25 ° C. using a self-made bead mill. After removing the beads, a pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 180 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion K.

  Using this pigment dispersion K instead of the pigment dispersion A, a recording liquid was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 3.

<Comparative example 2>
Pigment Blue-15: 3 (manufactured by Dainichi Seika Kogyo Co., Ltd .; powder; solid content: 100 wt%) 28.0 g, random copolymer I aqueous solution (random copolymer I concentration 10.0 wt%), 111.7 g, block copolymer X 14.4 g of an aqueous solution (block copolymer X concentration: 9.8% by weight) and 126.0 g of deionized water were mixed, and after pre-dispersion with CLEARMIX (manufactured by MTECHNIQUE; CLM-0.8S) for 1 hour, 0.3 mmφ A zirconia bead was used as a medium for dispersion for 8 hours at 25 ° C. using a self-made bead mill. After removing the beads, a pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 180 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain pigment dispersion L.

  Using this pigment dispersion L instead of the pigment dispersion A, a recording liquid was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 3.

<Comparative Example 3>
Pigment Yellow 155 (Clariant INK JET YELLOW 4G VP2532; powder; solid content 100.0 wt%) 28.0 g, random copolymer J aqueous solution (random copolymer J concentration 16.2 wt%) 35.0 g, block copolymer X aqueous solution (Block copolymer X concentration: 9.8% by weight) 43.0 g and deionized water 174.0 g were mixed, pre-dispersed for 10 minutes with a homomixer, and then at 25 ° C. using a bead mill with 0.3 mmφ zirconia beads as media. And after removing the beads, the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 120 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) to obtain a pigment dispersion M.

  Using this pigment dispersion M instead of the pigment dispersion A, a recording liquid was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 3.

<Comparative example 4>
Pigment Yellow 155 (Clariant INK JET YELLOW 4G VP2532; powder; solid content 100.0% by weight) 28.0 g, random copolymer K aqueous solution (random copolymer K concentration 15.7% by weight) 35.7 g, block copolymer X aqueous solution (Block copolymer X concentration: 9.8 wt%) 43.0 g and deionized water 173.3 g were mixed, pre-dispersed for 10 minutes with a homomixer, and then at 25 ° C. using a bead mill with 0.3 mmφ zirconia beads as the medium. And after removing the beads, the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 120 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; chip used: 36 mmφ) to obtain pigment dispersion N.

  Using this pigment dispersion N instead of the pigment dispersion A, a recording liquid was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 3.

<Comparative Example 5>
Pigment Blue-15: 3 (manufactured by Dainichi Seika Kogyo Co., Ltd .; powder; solid content 100 wt%) 28.0 g, random copolymer L aqueous solution (random copolymer L concentration 20.5 wt%) 136.6 g, block copolymer X aqueous solution (Block copolymer X concentration 9.8% by weight) 1.4 g and deionized water 114.0 g were mixed, and after pre-dispersion for 1 hour with CLEARMIX (MTECHNIQUE; CLM-0.8S), 0.3 mmφ Using zirconia beads as a medium, a self-made bead mill was used for dispersion for 1 hour at 25 ° C. After removing the beads, the pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) for 120 minutes to obtain a pigment dispersion O.

  Using this pigment dispersion O instead of the pigment dispersion A, a recording liquid was prepared in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 3.

<Comparative Example 6>
Carbon black (Mitsubishi Chemical Corporation: # 990) 28.0 g, random copolymer M aqueous solution (random copolymer M concentration 11.1 wt%) 101.3 g, and deionized water 150.7 g were mixed, and 0.5 mmφ Using a self-made bead mill using zirconia beads as a medium, dispersion was performed at room temperature for 8 hours, and after removing the beads, a pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; used chip 36 mmφ) for 30 minutes to obtain a pigment dispersion P.

  Using this pigment dispersion P instead of the pigment dispersion E, a recording liquid was prepared in the same manner as in Example 5 and evaluated in the same manner. The results are shown in Table 3.

<Comparative Example 7>
Carbon black (Mitsubishi Chemical Corporation: # 960) 28.0 g, random copolymer N aqueous solution (random copolymer N concentration 14.0 wt%) 119.8 g, and deionized water 132.2 g were mixed, and 0.5 mmφ was mixed. Using a self-made bead mill using zirconia beads as a medium, dispersion was performed at 25 ° C. for 8 hours, and after removing the beads, a pigment concentration was adjusted to 8% by weight to obtain a dispersion.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed with an ultrasonic homogenizer (Nippon Seiki Seisakusho, US-600T; used chip 36 mmφ) for 30 minutes to obtain pigment dispersion Q.

  Using this pigment dispersion Q instead of the oxyalkylene chain monomer dispersion E, a recording liquid was prepared and evaluated in the same manner as in Example 5. The results are shown in Table 3.

<Comparative Example 8>
Firing product carbon black (# 2300B (manufactured by Mitsubishi Chemical Corporation) under nitrogen atmosphere at 1200 ° C. for 1 month; powder; solid content 100% by weight) 28.0 g, random copolymer O aqueous solution (random copolymer O concentration 13) 8 wt%) 81.0 g, block copolymer X aqueous solution (block copolymer X concentration 9.8 wt%) 14.3 g, and deionized water 156.7 g were mixed, and Claremix (manufactured by MTECHNIQUE; CLM-0. After pre-dispersing at 8S) for 1 hour, 0.3 mmφ zirconia beads were dispersed as a medium using a self-made bead mill at 60 ° C. for 8 hours.

<Comparative Example 9>
Firing product carbon black (# 2300B (manufactured by Mitsubishi Chemical Corporation) under nitrogen atmosphere at 1200 ° C. for 1 month; powder; solid content 100% by weight) 28.0 g, random copolymer P aqueous solution (random copolymer P concentration 14) 7 wt%) 76.0 g, block copolymer X aqueous solution (block copolymer X concentration 9.8 wt%) 14.4 g, and deionized water 161.7 g were mixed, and CLEARMIX (manufactured by MTECHNIQUE; CLM-0. 8S), pre-dispersed for 1 hour, 0.3mmφ zirconia beads were used as media to disperse for 8 hours at 60 ° C using a self-made bead mill. After removing the beads, the dispersion was adjusted to a pigment concentration of 8% by weight. Obtained.

  The above dispersion was placed in a 500 ml tall beaker, the beaker was immersed in ice water, and dispersed for 120 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho; US-600T; chip used: 36 mmφ) to obtain a pigment dispersion R.

  Using this pigment dispersion R instead of the pigment dispersion E, a recording liquid was prepared in the same manner as in Example 5 and evaluated in the same manner. The results are shown in Table 3.

  The pigments and random copolymers used in the recording liquids of the examples and comparative examples are summarized in Table 2.

  From Tables 2 and 3, the following is clear.

Comparative Examples 1, 3, and 4 are those using random copolymers H, J, and K obtained by copolymerizing a hydrophobic monomer, an oxyalkylene chain monomer, and an anionic monomer, but the weight average molecular weight (Mw) is Since it is low, the heat resistance of the recording liquid is insufficient.

  Comparative Example 2 uses a random copolymer I obtained by copolymerizing a hydrophobic monomer, an oxyalkylene chain monomer, and an anionic monomer. However, since the weight average molecular weight (Mw) is low, printing performance is poor. I can't get anything.

  Comparative Example 5 uses a random copolymer L obtained by copolymerizing a hydrophobic monomer and an anionic monomer, but has no oxyalkylene chain and has a low weight average molecular weight (Mw). Since the gloss value of the printed matter is lower than that of No. 2 and thus the haze / gloss value is also high, both glossiness and sharpness are insufficient.

  Comparative Example 6 uses a random copolymer M obtained by copolymerizing a hydrophobic monomer, an oxyalkylene chain monomer, and an anionic monomer, and has a low weight average molecular weight (Mw) and a hydrophobic monomer structural unit. / Since the value of the oxyalkylene chain monomer structural unit (weight ratio) exceeds 0.8, the gloss value of the printed matter is lower than that of Example 5 using the same carbon black. Since the gloss value is high, both glossiness and sharpness are insufficient.

  Comparative Example 7 uses a random copolymer N obtained by copolymerizing a hydrophobic monomer and an oxyalkylene chain monomer, but does not contain an anionic monomer structural unit, so the heat resistance of the recording liquid is poor, The printed material has poor scratch resistance.

  Comparative Example 8 uses a random copolymer O obtained by copolymerizing a hydrophobic monomer, an oxyalkylene chain monomer, and an anionic monomer, but the anionic monomer structural unit constituting the polymer exceeds 60% by weight. It was impossible to disperse.

  Comparative Example 9 uses a polymer P obtained by copolymerizing a hydrophobic monomer, an oxyalkylene chain monomer, an anionic monomer, and another polymerizable monomer. The hydrophobic monomer structural unit constituting the polymer / Since the value of the oxyalkylene chain monomer structural unit (weight ratio) is smaller than 0.15, the average particle size of the pigment in the recording liquid is large and no discharge is performed.

  On the other hand, in Examples 1 to 10 using the polymers A to G, which are the polymers (I) according to the present invention, the heat resistance of the recording liquid is good and the discharge property is also better than these comparative examples. Although it is good, the scratch resistance of the printed matter is also good, and both the glossiness and the sharpness are excellent, and it is clear that the printing properties, particularly the glossiness for photographic paper, is excellent.

  From the above results, a water-soluble polymer obtained by copolymerizing one or more hydrophobic monomers, one or more specific oxyalkylene chain monomers and one or more anionic monomers, and the water-soluble polymer The anionic monomer structural unit constituting the water-soluble polymer having a value of the hydrophobic monomer structural unit constituting the oxyalkylene chain monomer structural unit (weight ratio) of 0.15 to 0.80 The present invention uses as a dispersant a polymer (I) whose amount is 1 to 60% by weight of the whole polymer and whose weight average molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography) is 21,000 or more. For recording liquids using water-based pigment dispersions, conventional styrene-acrylic dispersants and oxyalkylene chain monomers are used. Solvent resistance and ejection properties are higher than recording liquids using pigment dispersions prepared with different dispersants, and the printed matter obtained from the recording liquids is excellent in gloss, sharpness, and scratch resistance, and has a high print quality. It is clear that it is good.

Claims (9)

In an aqueous pigment dispersion comprising (a) an aqueous medium, (b) a pigment, and (c) a dispersant,
The (c) dispersant is obtained by copolymerizing one or more hydrophobic monomers and one or more oxyalkylene chain monomers represented by the following general formula (1) and one or more anionic monomers. Including a water-soluble polymer,
The content weight ratio of the hydrophobic monomer structural unit and the oxyalkylene chain monomer structural unit constituting the water-soluble polymer is 0.15 to 0.80,
The content of the anionic monomer structural unit constituting the water-soluble polymer is 1 to 60% by weight of the whole polymer,
A water-based pigment dispersion for printing, wherein the water-soluble polymer has a polystyrene-reduced weight average molecular weight of 21,000 or more as measured by GPC (gel permeation chromatography).

(Wherein R ¹ represents a vinyl group, an acryloyloxy group, an acryloylamino group, a methacryloyloxy group, a methacryloylamino group, an acrylamino group, a styryl group, a vinyl ether group, a vinylsilyl group, a cyanovinyl group, or a 2-cyanoacryloyl group. , R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group which may be substituted with an alkyl group, h and j are each independently an integer of 1 to 5, i and k are i + k is an integer satisfying 2 to 50.)   The aqueous pigment dispersion for printing according to claim 1, wherein the anionic monomer is a carboxylic acid and / or a salt thereof.   The aqueous pigment dispersion for printing according to claim 1 or 2, wherein the average dispersed particle size of the pigment (b) is 300 nm or less.   The aqueous pigment dispersion for printing according to any one of claims 1 to 3, wherein the oxyalkylene chain of the oxyalkylene-containing monomer is an oxyethylene chain.   The aqueous pigment dispersion for printing according to any one of claims 1 to 4, wherein the hydrophobic monomer contains an aromatic group and / or an aliphatic hydrocarbon group. The aqueous pigment dispersion for printing according to any one of claims 1 to 5, wherein R ² in the general formula (1) is an alkyl group having 1 to 20 carbon atoms or a phenyl group which may be substituted with an alkyl group.   The method for producing an aqueous printing pigment dispersion according to any one of claims 1 to 6, wherein the aqueous printing pigment dispersion has a step of dispersing (b) a pigment and (c) a dispersant in a medium. A method for producing an aqueous pigment dispersion for printing, wherein only water is used as the medium.   An ink composition comprising the aqueous pigment dispersion for printing according to any one of claims 1 to 7.   An ink jet recording method, comprising: ejecting droplets of the ink composition according to claim 8 from an ink jet head and attaching the droplets to a recording medium.