JP2000219749A - Aqueous pigment dispersion and aqueous recording liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous pigment dispersion which is sufficiently satisfactory in every aspects such as the dispersion stability, dispersion viscosity, etc., and an aqueous recording liquid containing the dispersion. SOLUTION: An aqueous pigment dispersion contains at least a pigment and an anionic group-containing organic polymer compound, wherein the anionic group-containing organic polymer compound has a solubility parameter of 9.0 to 10.0. Preferably, the anionic group-containing organic polymer compound contains as constituents one or more compounds chosen from the group consisting of a 3-5C alkyl acrylate and methacrylic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous pigment dispersion, a method for producing the same, and an aqueous recording liquid using the pigment dispersion.

[0002]

2. Description of the Related Art Conventionally, dyes have been used as coloring materials for writing instruments such as felt-tip pens and water-based markers and inks for ink jet printers. Recording liquids using dyes are excellent in coloring power and sharpness, but have problems in light resistance, water resistance and the like.

To solve the problems of light fastness and water fastness,
In recent years, conversion of colorants from dyes to pigments has been actively studied in the application fields described above. The use of pigments as colorants in this field, especially in the field of ink-jet inks, requires very high levels of dispersibility and dispersion stability in solid-liquid two-phase pigment dispersions. As means for achieving such a high degree of dispersibility and dispersion stability, JP-A-9-151342 discloses a microencapsulated pigment dispersion in which a pigment is coated with an anionic group-containing organic polymer compound.

[0004]

However, the microencapsulated pigment dispersions described in the above publications also have a satisfactory level of dispersion attainment, dispersion stability, dispersion viscosity, etc., especially for yellow and red pigments. It was not satisfactory.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have obtained an aqueous pigment dispersion containing at least a pigment and an organic polymer compound having an anionic group, An aqueous pigment dispersion characterized by using an anionic group-containing organic polymer compound having a solubility parameter in a specific range as the anionic group-containing organic polymer compound was found to satisfy such various requirements, and the present invention Was completed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The aqueous pigment dispersion of the present invention is an aqueous pigment dispersion containing at least a pigment and an organic polymer compound having an anionic group, and has a solubility parameter as the organic polymer compound having an anionic group. Is 9.0-1
It is characterized by using an anionic group-containing organic polymer compound of 0.0.

The anionic group-containing organic high molecular compound having a solubility parameter of 9.0 to 10.0 is itself known as a very small part of an enormous variety of commonly used organic high molecular compounds.

[0008] The solubility parameter is one index of the polarity of the organic polymer compound. When the organic polymer compound is a (meth) acrylate-based copolymer, the solubility parameter of the constituent monomer is considered as a homopolymer. It can be calculated from the intrinsic Sp value and the usage ratio (copolymerization ratio) of those constituent monomers.

The anionic group-containing organic polymer compound having the specific solubility parameter range used in the aqueous pigment dispersion of the present invention is not particularly limited as long as it has an anionic group. Anionic group-containing organic polymer compounds obtained by copolymerizing anionic group-containing monomers containing a sulfone group, a phospho group, a thiocarboxyl group, and the like, and other monomers copolymerizable with these anionic group-containing monomers are listed. However, in consideration of the availability of raw material monomers, price, etc., anionic group-containing organic polymer compounds containing a carboxyl group or a sulfone group are preferable, and the coexistence range of the electric neutral state and the anionic state is wide. From the viewpoint of control, an anionic group-containing organic polymer compound containing a carboxyl group is particularly preferable.

The anionic group-containing organic polymer compound having the specific solubility parameter range used in the aqueous pigment dispersion of the present invention may have, for example, a crosslinked portion.
There is an organic polymer compound having an anionic group.

Typically, an acrylate polymer having an anionic group having a crosslinking portion, an acrylate polymer having an anionic group having no crosslinking portion, having an anionic group having a crosslinking portion There are methacrylate-based polymers and methacrylate-based polymers having an anionic group having no cross-linked portion. In the present invention, both (meth) acrylate and methacrylate are referred to as (meth) acrylate. The (meth) acrylate-based polymer means a polymer obtained by polymerizing (meth) acrylate as a main component.

The most suitable organic polymer compound having an anionic group is an organic polymer compound having an anionic group in which the anionic group contains both a carboxyl group and a carboxylate group.

Examples of the monomer having a carboxyl group include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid and 4-vinylbenzoic acid; vinyl succinate, allyl maleate And polybasic unsaturated esters such as vinyl terephthalate and allyl trimellitate. Examples of monomers containing a sulfonic acid group include unsaturated sulfo-substituted alkyl or aryl esters such as 2-sulfoethyl acrylate and 4-sulfophenyl methacrylate; unsaturated sulfocarboxylic acids such as vinyl sulfosuccinate; Sulfostyrenes such as styrene-4-sulfonic acid;

Examples of other monomers which can be copolymerized with the anionic group-containing monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic T-butyl acid, 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, isobornyl acrylate, benzyl acrylate, 2,3-epoxypropyl acrylate, 2,2 acrylate 3
-Epoxybutyl, 2,3-epoxycyclohexyl acrylate, vinyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate , 2-ethylhexyl methacrylate, n-octyl methacrylate,
Dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, benzyl methacrylate, 2,3-epoxypropyl methacrylate, 2,3-epoxybutyl methacrylate,
2,3-epoxycyclohexyl methacrylate, vinyl methacrylate, dimethyl maleate, diethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl itaconate, benzyl itaconate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-aminoethyl acrylate, 2-aminopropyl acrylate, 3-aminopropyl acrylate, 2- (methylamino) ethyl acrylate, 2-acrylate (Methylamino) propyl, 2- (ethylamino) ethyl acrylate, 2- (ethylamino) acrylate
Propyl, 2- (dimethylamino) ethyl acrylate,
Unsaturated fatty acid esters such as 3- (dimethylamino) propyl acrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-dipropylacrylamide , N- (2-aminoethyl) acrylamide, N-
(2-aminopropyl) acrylamide, N- (3-aminopropyl) acrylamide, N- [2- (methylamino) ethyl] acrylamide, N- [2- (methylamino) propyl] acrylamide, N- [3- ( Methylamino) propyl] acrylamide, N- [2- (dimethylamino) ethyl] acrylamide, N- [2- (dimethylamino) propyl] acrylamide, N- [3-
(Dimethylamino) propyl] acrylamide, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide, N
-Dimethyl methacrylamide, N-diethyl methacrylamide, N-dipropyl methacrylamide, N- (2-
Aminoethyl) methacrylamide, N- (2-aminopropyl) methacrylamide, N- (3-aminopropyl) methacrylamide, N- [2- (methylamino) ethyl] methacrylamide, N- [2- (methylamino) )
Propyl] methacrylamide, N- [3- (methylamino) propyl] methacrylamide, N- [2- (dimethylamino) ethyl] methacrylamide, N- [2- (dimethylamino) propyl] methacrylamide, N- [ 3
-(Dimethylamino) propyl] methacrylamide, maleamide, N, N-dimethylmaleamide, fumaramid,
Unsaturated fatty acid amides such as N, N-dimethyl fumamide; unsaturated nitriles such as acrylonitrile, methacrylonitrile; vinyl acetate, vinyl propionate, vinyl butanoate, vinyl hexanoate, vinyl 2-ethylhexanoate Carboxylic acid unsaturated esters such as octadecanoate, vinyl benzoate, allyl acetate, allyl propionate, allyl hexanoate and allyl decanoate; ethyl vinyl ether, butyl vinyl ether, 2-polyoxyethylene-2- (4- Unsaturated ethers such as nonylphenoxy) methylethyl allyl ether; styrene, α
-Methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, pt-butylstyrene, 4-methoxystyrene, 4-chlorostyrene, and other styrenes; ethylene, propylene, 1-butene, 1- Unsaturated hydrocarbons such as octene, vinylcyclohexane and 4-vinylcyclohexene; unsaturated halogenated hydrocarbons such as vinyl chloride, vinylidene chloride, tetrafluoroethylene and 3-chloropropylene; 4-vinylpyridine, N- Vinyl-substituted heterocyclic compounds such as vinylcarbazole, N-vinylpyrrolidone, etc .; monomers having a substituent having an active hydrogen such as a carboxyl group, a hydroxyl group, or an amino group in the above-exemplified monomers, and ethylene oxide, propylene oxide, and cyclohexene oxide Reaction products with epoxides; Hydroxyl group of the serial exemplified in the monomer,
A monomer containing a substituent having an amino group or the like and acetic acid,
Reaction products with carboxylic acids such as propionic acid, butanoic acid, hexanoic acid, decanoic acid and dodecanoic acid can be mentioned.

In the case where the organic polymer compound having the specific solubility parameter is selected from (meth) acrylate copolymers, it is preferred that the organic polymer be selected from the group consisting of alkyl esters of acrylic acid and methacrylic acid having at least 3 to 5 carbon atoms. One or more selected compounds are used as constituents, and a copolymer obtained by polymerizing with other monomers is selected, or at least selected from the group consisting of alkyl esters of acrylic acid and methacrylic acid having 3 to 5 carbon atoms. From the viewpoint of performance, it is preferable to select a copolymer containing one or more compounds as constituent elements and styrene as a constituent element, and the latter copolymer is most preferable.

In the present invention, the solubility parameter of the anionic group-containing organic polymer compound is a numerical value obtained by summing the solubility parameters of the homopolymers of the respective constituent monomers in accordance with the weight fraction. This is a calculated value calculated as being present.

The Sp value of the homopolymer of each constituent monomer is as described in Wiley & Sons "Polymer Handbook". For example, some of them are as follows.

N-butyl methacrylate 8.25 n-butyl acrylate 8.63 2-hydroxyethyl methacrylate 9.90 Styrene 9.35 Methacrylic acid 13.11 Acrylic acid 12.89 2,3-Epoxypropyl methacrylate 8.30

More specifically, the Sp value of the organic polymer compound used in the present invention is calculated from the Sp value of the homopolymer of each constituent monomer as follows: Sp = 8.25 * X1 + 8.63 * X
2 +… can be calculated.

Since monomers having similar chemical structures have similar Sp values when homopolymerized, means for realizing copolymer Sp values 9 to 10 when copolymerized are as follows:
This can be achieved by changing the chemical structure of each constituent monomer and its copolymerization ratio. As one method, for example,
Examples include using methyl methacrylate or maleic acid.

Such an anionic group-containing organic polymer compound can be synthesized by various conventionally known reaction methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization.

The weight average molecular weight of the organic polymer compound having an anionic group used in the present invention is from 2,000 to 100,
5,000, preferably 5,000 to 5
It is particularly preferred that it is in the range of 000. If the weight-average molecular weight is too small, the dispersion stability of the aqueous pigment dispersion itself decreases, and if it is too large, not only the viscosity of the dispersion increases but also the dispersibility tends to decrease. If the weight average molecular weight is too small or too large, for example, when applied to an ink for an ink jet printer, it adversely affects the printing characteristics and makes it difficult to perform stable printing for a long period of time.

The acid value and glass transition point of the anionic group-containing organic polymer compound used in the present invention are preferably in the range of 30 to 220 mg KOH / g and -20 to 60 ° C., respectively. If the acid value is too low, the dispersibility and dispersion stability of the aqueous pigment dispersion will decrease, and the printing stability when applied to inks for inkjet printers will deteriorate. If the acid value is too high, the water resistance of the image will decrease when applied to an ink for an inkjet printer. If the glass transition point is too high, stable printing is difficult to obtain, and if it is too low, image storability such as abrasion resistance and bar-stacking resistance tends to decrease.

The anionic group-containing organic polymer compound in the aqueous pigment dispersion of the present invention has a dispersibility and a dispersion stability in which at least a part of the anionic group is ionized by a basic substance. Is preferred in terms of expression of The optimal ratio of the ionized group among the anionic groups is determined by the composition of the used anionic group-containing organic polymer compound,
Although it is not uniquely limited because it changes depending on the molecular weight, the acid value, and the like, it may be within a range in which desired dispersibility and dispersion stability are exhibited, and usually 30 to 100%, particularly 70 to 100%.
Preferably, it is set in the range of 100%. The ratio of the ionized group does not mean the molar ratio between the anionic group and the basic substance, but takes into account dissociation equilibrium. For example, when the anionic group is a carboxyl group, the ratio of the group ionized by dissociation equilibrium is less than 100% even when a stoichiometrically equivalent amount of a strong basic substance is used, and the ratio of the carboxylate group and the carboxyl group is less than 100%. It is a mixed state.

As described above, as the basic substance used to ionize at least a part of the anionic group of the organic polymer compound containing anionic group, known basic substances may be used. Preferred are compounds selected from the group consisting of primary, secondary and tertiary organic amines (including basic nitrogen-containing heterocyclic compounds) and alkali metal hydroxides. By ionizing at least a part of the anionic group with these exemplified suitable basic substances, the counter ion of the carboxylate group becomes ammonium ion (including the protonated cation of the basic nitrogen-containing heterocyclic compound), alkali It becomes a cation selected from the group consisting of metal ions.

According to the findings of the present inventors, as an effect of the resin polarity in the dispersion of the aqueous pigment, the interaction with the pigment which is a hydrophobic substance is preferably somewhat hydrophobic (the Sp value is small). It is considered that hydrophilicity is more preferable for stabilizing the dispersion of, and it is considered that the above-mentioned optimum range appears in the Sp value as a result of the balance between the factors having a trade-off relationship between the two.

The pigment that can be used in the aqueous pigment dispersion of the present invention is not particularly limited. However, in order to take advantage of the high dispersibility and dispersion stability that are features of the present invention, small pigments are used for primary particles. It is preferable to use a hydrophobic pigment,
For example, various organic pigments and carbon black are particularly effectively used.

Examples of organic pigments include C.I. I. Pigment Red 122, Red 202, Red 20
Quinacridone pigments such as Red 209 and Red 209 and Violet 19; I. Pigment Orange 48,
Quinacridone quinone pigments such as Orange 49;
I. Dioxazine pigments such as C.I. Pigment Violet 23 and Violet 37; I. Pigment Blue 15, Blue 15: 1, Blue 15: 2,
Same Blue 15: 3, Same Blue 15: 4, Same Blue 1
5: 6, phthalocyanine pigments such as Blue 16, Blue 68, Green 7, and Green 36;
C. I. Anthrapyrimidine pigments such as CI Pigment Yellow 108; I. Pigments such as C.I. Pigment Orange 77 and Red 168; I. Pigment Blue 60 and other indanthrone-based pigments;
I. Flavanthrone-based pigments such as CI Pigment Yellow 24; I. Anthraquinone pigments such as CI Pigment Yellow 196 and Red 177; I. Pigment Red 123, Red 149, Red 17
8, perylene pigments such as Red 179, Red 190, and Red 224; I. Perinone pigments such as CI Pigment Yellow 196 and Orange 43;
C. I. Quinophthalone pigments such as CI Pigment Yellow 138; I. Pigment Orange 71, Orange 73, Red 254, Red 255,
Diketopyrrolopyrrole pigments such as Red 264 and Red 272; I. Thioindigo pigments such as CI Pigment Red 88, Red 181 and Brown 27; I. Isoindoline pigments such as CI Pigment Yellow 139, Yellow 185, Orange 69, and Red 260; I. Pigment Yellow 1
Isoindolinone-based pigments such as C.09, Yellow 110 and Yellow 173; I. Azomethine pigments such as CI Pigment Yellow 101, Yellow 129 and Orange 65; I. Pigment Yellow 15
1, yellow 154, yellow 175, yellow 180, yellow 181, orange 36,
Red 175, Red 176, Red 185
Benzimidazolone pigments such as C.I. I. Pigment
Yellow 1, Yellow 65, Yellow 73, Yellow 74, Yellow 116, Red 3,
Red 48: 1, Red 48: 2, Red 48: 3, Red 53: 1, Red 57: 1
Monoazo pigments such as Red 115; I. Disazo pigments such as CI Pigment Yellow 12, Yellow 13, Yellow 17, Yellow 81, Yellow 83, Orange 13, Orange 16;
I. Pigment Yellow 93, Yellow 95, Yellow 128, Red 144, Red 16
6, condensed azo pigments such as Red 220, Red 221 and the like.

The pigment may be a powdery, granular or lumpy dry pigment, or may be a wet cake or a slurry.

In the aqueous pigment dispersion of the present invention, the ratio of the pigment to the organic polymer compound having an anionic group is from 25 to 2 parts by weight per 100 parts by weight of the pigment.
About 00 parts by weight is preferable. If the ratio of the anionic group-containing organic polymer compound is too low, the friction resistance when used as an aqueous recording liquid decreases, and if it is too high, the viscosity increases when the aqueous recording liquid is adjusted. A tendency is observed.

The aqueous pigment dispersion of the present invention can be produced by a process including a step of dispersing at least a mixture of a pigment, an organic polymer having an anionic group having a specific solubility parameter range, a basic substance and water. .

Examples of the steps other than the dispersing step which can be incorporated into the process for producing the aqueous pigment dispersion of the present invention include a preliminary dispersing step, a dissolving step, a dilution step, a distillation step, a centrifugal separation step, an acid precipitation step, a filtration step, Redispersion step, pH adjustment step,
And a filling step.

Examples of the pre-dispersing step include a step of mixing and dispersing a resin and a pigment in a solution state or a molten state to form a slurry, a paste, or a solid state called a masterbatch or a chip. Examples of the dissolving step include a step of dissolving a solid anionic group-containing organic polymer compound in an organic solvent, preferably a water-soluble organic solvent, or an aqueous medium containing a basic substance, or an anionic group-containing organic compound. There is a step of dissolving a water-soluble organic solvent solution of the polymer compound in an aqueous medium containing a basic substance.

In the present invention, a step of dispersing a mixture comprising a pigment, an organic polymer having an anionic group, a basic substance and water is essentially included. The mixture preferably contains a water-soluble organic solvent. More specifically, it is preferable to include a step of dispersing at least a mixture of a pigment, an anionic group-containing organic polymer compound, a basic substance, a water-soluble organic solvent, and water.

In the aqueous dispersion of the present invention, in order to exhibit more excellent properties in all aspects of the dispersion attained level, the required dispersion time, and the dispersion stability, the pigment is formed by an anionic group-containing organic polymer compound. It is preferred that the coated, encapsulated pigment be dispersed in the aqueous dispersion.
In order to form such a state, in a state where the pigment is dispersed in a liquid medium containing the anionic group-containing organic polymer compound, the anionic group-containing organic polymer in a dissolved state is used as the post-process. It is preferable to incorporate a step of coating the compound on the pigment surface.

The step of coating the surface of the pigment with the anionic group-containing organic polymer compound in a dissolved state is performed by acidifying the anionic group-containing organic polymer compound dissolved in the alkaline aqueous solution. The step of precipitating is preferred.

Examples of the distillation step include a step of removing an organic solvent when the organic solvent is used in the dispersion step, and a step of removing excess water to obtain a desired solid content concentration. Examples of the centrifugation step include a step of removing coarse particles in the dispersion that adversely affect the suitability for use as an aqueous recording liquid.

In the example of the acid precipitation step, the aqueous dispersion obtained in the dispersion step is acidified by adding an acid such as hydrochloric acid, sulfuric acid or acetic acid.
There is a step of depositing an anionic group-containing organic polymer compound on the surface of the pigment particles. This step can enhance the interaction between the pigment and the anionic group-containing organic polymer compound. Examples of the filtration step include a step of removing coarse particles in the dispersion using a cartridge filter or a membrane filter in the same manner as the centrifugation step, and a step of filtering the solid content after the above-mentioned acid precipitation step by using a filter press, a Nutsche type filtration device, and pressure filtration. There is a step of filtering by an apparatus or the like. Examples of the redispersion step include a step of adding a basic substance and, if necessary, water and additives to the solid obtained by the acid precipitation step and the filtration step to obtain a dispersion again. Thereby, the counter ion of the ionized anionic group in the anionic group-containing organic polymer compound can be changed from that used in the dispersion step.

In the present production method, at least one kind of the organic polymer compound having an anionic group having the specific solubility parameter range may be used. May be divided and used, and in that case, it is preferable to use an anionic group-containing organic polymer compound having the smallest solubility parameter first.

In the dispersing step, a water-soluble organic solvent can be used in combination, whereby the liquid viscosity in the dispersing step can be reduced in some cases. Examples of the water-soluble organic solvent include ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone; methanol, ethanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 2-methoxyethanol, Alcohols such as tetrahydrofuran,
Ethers such as 1,4-dioxane and 1,2-dimethoxyethane; and amides such as dimethylformamide and N-methylpyrrolidone. These water-soluble organic solvents may be used as an anionic group-containing organic polymer compound solution, or may be separately and independently added to the dispersion mixture.

As the dispersing device that can be used in the dispersing step, devices that are already known in various systems can be used and are not particularly limited. Examples thereof include steel, stainless steel, zirconia, alumina, silicon nitride, and the like.
A method using the kinetic energy of a spherical dispersion medium made of glass or the like having a diameter of about 0.1 to 10 mm, a method using a shearing force by mechanical stirring, a pressure change of a high-speed supplied distribution bundle, a flow path A dispersion method such as a method using a force generated by a change or a collision can be adopted.

As described above, in the present invention, as the anionic organic polymer compound, an anionic organic polymer compound having a crosslinked portion can be used.
However, in the use of the aqueous recording liquid described later, a high degree of dispersion stability is often required, and the crosslinking is completed in advance, and is carried out during transport, storage, and actual use (at the time of recording). Preferably, no reaction takes place.

In the present invention, when the organic polymer compound having an anionic group contains a crosslinkable group, for example, 2,3-epoxypropyl acrylate, 2,3-epoxybutyl acrylate, 2,3-epoxy acrylate A copolymer containing a monomer comprising at least one unsaturated fatty acid having an epoxy group such as cyclohexyl, 2,3-epoxypropyl methacrylate, 2,3-epoxybutyl methacrylate, 2,3-epoxycyclohexyl methacrylate, etc. In the case of coalescence, the ring-opening reaction can be carried out at any stage after the dispersion step in the aqueous dispersion production process to effect crosslinking. The ring opening reaction temperature is preferably about 80 to 140 ° C. When the reaction temperature is too low, the reaction rate is low and a long time is required for completing the reaction, so that the pigment particles are likely to fuse with each other to form an aggregate. If the reaction temperature is too high, fusion of the pigment particles and growth of the pigment particles themselves occur, which is not preferable in any case. When the reaction temperature becomes higher than the boiling point of the dispersion, it is necessary to use a pressurized reactor.

The recording liquid of the present invention is prepared by adding a water-soluble organic solvent, water, etc. to an aqueous pigment dispersion containing at least a pigment and an anionic group-containing organic high molecular compound having a solubility parameter of 9.0 to 10.0. It is prepared by mixing. If necessary, surfactant, water-soluble resin, preservative, viscosity modifier, p
An H adjuster, a chelating agent and the like can be added.

Examples of water-soluble organic solvents that can be used for preparing the recording liquid include methanol, ethanol, 1-
Propanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 2-methoxyethanol, 2-butoxyethanol, 2- (2-methoxyethoxy) ethanol, 2- (2-butoxyethoxy) ethanol, 2- [2- (2-methoxyethoxy) ethoxy] ethanol, 2- [2- (2-butoxyethoxy)
Ethoxy] alcohols such as ethanol; 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol, 2,3-butanediol, 2,2′-oxybisethanol, 2,2′- Ethylenedioxybis (ethanol), thiodiethanol, glycerin, 1,
Polyhydric alcohols such as 2,6-hexanetriol; amides such as dimethylformamide, dimethylacetamide, N-methyl-pyrrolidone, 1,3-dimethyl-2-imidazolidinone; acetone, methyl ethyl ketone, methyl n-butyl ketone; Ketones such as methyl isobutyl ketone; tetrahydrofuran, 1,4-dioxane,
1,2-dimethoxyethane, 1,2-diethoxyethane, 2,2′-oxybis (2-methoxyethane),
2,2′-oxybis (2-ethoxyethane), 2,
2′-ethylenedioxybis (2-methoxyethane),
Ethers such as 2,2′-ethylenedioxybis (2-methoxyethane) are exemplified. The content of the water-soluble organic solvent in the recording liquid is preferably 50% by weight or less,
A range of 40% by weight is particularly preferred.

The surfactant which may be added to the recording liquid of the present invention includes anionic, cationic, zwitterionic,
Any nonionic activator may be used.

Examples of the anionic surfactant include fatty acid salts such as sodium stearate, potassium oleate, and sodium hydrogenated tallow fatty acid; sodium dodecyl sulfate, tri (2-hydroxyethyl) ammonium dodecyl sulfate, and sodium octadecyl sulfate. Alkyl sulfates such as sodium nonylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium octadecylbenzenesulfonate, sodium dodecyldiphenyletherdisulfonate; sodium dodecylnaphthalenesulfonate;
Naphthalene sulfonic acid salts such as naphthalene sulfonic acid formalin condensate; sulfosuccinate ester salts such as sodium dododecyl sulfosuccinate and dioctadecyl sodium sulfosuccinate; sodium polyoxyethylene dodecyl ether sulfate, polyoxyethylene dodecyl ether sulfate Ethyl) ammonium, sodium polyoxyethylene octadecyl ether sulfate, sodium polyoxyethylene dodecyl phenyl ether sulfate and the like; and polyoxyethylene sulfate salts such as potassium dodecyl phosphate and sodium octadecyl phosphate.

Examples of the cationic surfactant include alkylamine salts such as octadecyl ammonium acetate and coconut oil amine acetate; dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dioctadecyldimethylammonium chloride, dodecylbenzyldimethylammonium chloride and the like. Quaternary ammonium salts.

Examples of zwitterionic activators include alkyl betaines such as dodecyl betaine and octadecyl betaine; and amine oxides such as dodecyl dimethyl amine oxide.

Examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene octadecyl ether, and polyoxyethylene (9-octadecenyl) ether. Polyoxyethylene phenyl ethers such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether; oxirane polymers such as polyethylene oxide and co-polyethylene oxide propylene oxide; sorbitan dodecanoate and sorbitan hexadecanoate Sorbitan octadecanoate, sorbitan (9-octadecenoate) ester, sorbitan (9-octadecenoate) triester, polyoxyethylene sorbita Dodecanoic acid ester, polyoxyethylene sorbitan hexadecanoic ester, polyoxyethylene sorbitan octadecanoic ester, polyoxyethylene sorbitan octadecanoic acid triester,
Polyoxyethylene sorbitan (9-octadecenoic acid)
Esters, sorbitan fatty acid esters such as polyoxyethylene sorbitan (9-octadecenoic acid) triester; sorbitol fatty acid esters such as polyoxyethylene sorbitol (9-octadecenoic acid) tetraester; glycerin octadecanoate, glycerin (9-octadecene) Glycerin fatty acid esters such as (acid) esters. Among these nonionic surfactants, those having an HLB of 14 or more are particularly preferred.

Examples of the water-soluble resin which may be added to the aqueous recording liquid of the present invention include glue, gelatin, casein,
Albumin, gum arabic, fish gleu, alginic acid, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyethylene oxide,
Polyvinyl alcohol, polyacrylamide, polyacrylic acid, polyvinyl ether, polyvinylpyrrolidone,
Styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylate-acrylic acid copolymer and the like can be mentioned.

The water-soluble resin is used as needed for the purpose of improving fixability, adjusting viscosity and drying quickly.
When used in the recording liquid, the content of the water-soluble resin in the recording liquid is preferably 0 to 30% by weight or less, and 0 to 20% by weight.
The following are particularly preferred.

The aqueous recording liquid of the present invention can be suitably used as an ink for stationery such as a felt-tip pen, a marker, etc. and various printers and plotters. It can be suitably used as an ink for use.

The present invention includes the following specific embodiments. 1. An aqueous pigment dispersion containing at least a pigment and an anionic group-containing organic high molecular compound, wherein the anionic group-containing organic high molecular compound has a solubility parameter of 9.0 to 10.0. An aqueous pigment dispersion comprising a molecular compound.

2. The anionic group-containing organic polymer compound is an anionic group-containing organic polymer compound containing, as a constituent element, at least one compound selected from the group consisting of alkyl esters of acrylic acid and methacrylic acid having 3 to 5 carbon atoms. 2. The aqueous pigment dispersion according to the above item 1.

3. The anionic group-containing organic polymer containing at least one compound selected from the group consisting of alkyl esters of acrylic acid and methacrylic acid having 3 to 5 carbon atoms and styrene as an anionic group-containing organic polymer compound. 2. The aqueous pigment dispersion according to the above 1, which is a molecular compound.

4. 4. The aqueous pigment dispersion according to any one of the above 1 to 3, wherein the pigment is an organic pigment or carbon black.

5. 5. The aqueous pigment dispersion according to any one of the above 1 to 4, wherein the pigment is coated with an anionic group-containing organic polymer compound.

6. 6. The aqueous pigment dispersion according to any one of the above 1 to 5, wherein the anionic groups are a carboxyl group and a carboxylate group.

7. The counter ion of the carboxylate group is
7. The aqueous pigment dispersion according to the above 6, which is a cation selected from the group consisting of an organic ammonium ion and an alkali metal ion.

8. 8. The aqueous pigment dispersion according to any one of the above 1 to 7, wherein the weight average molecular weight of the organic polymer compound having an anionic group is from 5,000 to 50,000.

9. The above-mentioned 1-8, wherein the acid value of the organic polymer compound containing an anionic group is 30-220 mgKOH / g.
An aqueous pigment dispersion as described in the above.

10. The aqueous pigment dispersion according to any one of the above 1 to 9, wherein the glass transition point of the organic polymer compound having an anionic group is from -20 to 60 ° C.

11. 11. The aqueous pigment dispersion according to any one of the above items 1 to 10, wherein the ratio of the pigment to the anionic group-containing organic polymer compound is 25 parts to 200 parts by weight based on 100 parts by weight of the pigment.

12. An aqueous recording liquid comprising the aqueous pigment dispersion according to any one of the above 1 to 11.

[0066]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. In the following Examples and Comparative Examples,
“Parts” and “%” represent “parts by weight” and “% by weight”.

<Synthesis Example 1> (Synthesis of Anionic Group-Containing Organic Polymer Compound A-1) An automatic reactor having a stirrer, a dropping device, a temperature sensor, and a reflux vessel equipped with a nitrogen introducing device on the top was installed. In a reaction vessel of a polymerization reactor (polymerization tester DSL-2AS type, manufactured by Todoroki Sangyo Co., Ltd.), methyl ethyl ketone 1,0 was added.
Then, the reaction vessel was purged with nitrogen while stirring. After the temperature was raised to 75 ° C. while maintaining the inside of the reaction vessel in a nitrogen atmosphere, n-butyl methacrylate 79 was supplied from a dropping device.
1.5 parts, n-butyl acrylate 21.2 parts, 2-hydroxyethyl methacrylate 80.0 parts, methacrylic acid 1
07.3 parts and “Perbutyl O” (active ingredient t-butyl peroxy-2-ethylhexanoate, NOF Corporation)
20.0 parts of a mixed solution was added dropwise over 2 hours.

After completion of the dropwise addition, the reaction was further continued at the same temperature for 15 hours to obtain a dissolution parameter of 8.91, an acid value of 69, a glass transition temperature (calculated value) of 30 ° C., a weight average molecular weight of 18,
200 anionic group-containing organic polymer compound solutions were obtained. After completion of the reaction, a part of methyl ethyl ketone was distilled off under reduced pressure to adjust the nonvolatile content of the resin solution to 50%.

Also in the following synthesis examples, the nonvolatile content of the resin solution was adjusted to 50% by distilling or adding the solvent under reduced pressure.

<Synthesis Example 2> (Synthesis of Anionic Group-Containing Organic Polymer Compound A-2) The monomer composition was 700.1 parts of n-butyl methacrylate,
42.6 parts of n-butyl acrylate, 150.0 parts of 2-hydroxyethyl methacrylate, 107.3 parts of methacrylic acid
In the same manner as in Synthesis Example 1 except that 20.0 parts of “perbutyl O” was changed to 80.0 parts, the dissolution parameter 9.04, the acid value 68, and the glass transition temperature (calculated value) 30 were used.
An organic polymer compound solution having an anionic group having a weight average molecular weight of 20,300 at ℃ was obtained.

<Synthesis Example 3> (Synthesis of Organic Polymer Compound A-3 Containing Anionic Group) The monomer composition was 685.7 parts of n-butyl methacrylate,
Except having changed to 25.3 parts of n-butyl acrylate, 150.0 parts of 2-hydroxyethyl methacrylate, and 139.0 parts of acrylic acid, a solubility parameter of 9.15, an acid value of 108, Glass transition temperature (calculated value) 3
An organic polymer compound solution containing an anionic group having a weight average molecular weight of 24,700 at 0 ° C. was obtained.

<Synthesis Example 4> (Synthesis of Anionic Group-Containing Organic Polymer Compound A-4) The monomer composition was changed to 377.7 parts of n-butyl methacrylate,
165.0 parts of n-butyl acrylate, 2-methacrylic acid 2-
150.0 parts of hydroxyethyl, methacrylic acid
Dissolution parameters 9.30, acid value 70, glass transition temperature (calculated value) 30 ° C, weight average molecular weight 23,
800 anionic group-containing organic polymer compound solutions were obtained.

<Synthesis Example 5> (Synthesis of Anionic Group-Containing Organic Polymer Compound A-5) The monomer composition was changed to 450.4 parts of n-butyl methacrylate,
127.6 parts of n-butyl acrylate, 2-methacrylic acid 2-
75.0 parts of hydroxyethyl, 167.0 parts of acrylic acid
Synthesis Example 2 except that the amount of styrene was changed to 180.0 parts.
In the same manner as described above, the melting parameter is 9.39, the acid value is 130, the glass transition temperature (calculated value) is 30 ° C., the weight average molecular weight is 27,
300 anionic group-containing organic polymer compound solutions were obtained.

<Synthesis Example 6> (Synthesis of Organic Polymer Compound A-6 Containing Anionic Group) The monomer composition was 535.1 parts of n-butyl methacrylate,
10.6 parts of n-butyl acrylate, 75.0 parts of 2-hydroxyethyl methacrylate, 199.3 parts of methacrylic acid
Synthesis Example 2 except that the amount of styrene was changed to 180.0 parts.
In the same manner as described above, the melting parameter 9.53, the acid value 130, the glass transition temperature (calculated value) 53 ° C., the weight average molecular weight 23,
300 anionic group-containing organic polymer compound solutions were obtained.

<Synthesis Example 7> (Synthesis of Anionic Group-Containing Organic Polymer Compound A-7) The monomer composition was changed to 337.6 parts of n-butyl methacrylate,
208.1 parts of n-butyl acrylate, 2-methacrylic acid 2-
75.0 parts of hydroxyethyl, 199.3 methacrylic acid
Synthesis Example 2 except that the amount of styrene was changed to 180.0 parts.
In the same manner as described above, the melting parameter 9.61, the acid value 130, the glass transition temperature (calculated value) 30 ° C., the weight average molecular weight 24,
As a result, 900 anionic group-containing organic polymer compound solutions were obtained.

<Synthesis Example 8> (Synthesis of Anionic Group-Containing Organic Polymer Compound A-8) The monomer composition was changed to 405.2 parts of n-butyl methacrylate,
45.5 parts of n-butyl acrylate, 150.0 parts of 2-hydroxyethyl methacrylate, 199.3 parts of methacrylic acid
Synthesis Example 2 except that the amount of styrene was changed to 200.0 parts.
In the same manner as described above, the melting parameter is 9.70, the acid value is 130, the glass transition temperature (calculated value) is 53 ° C., the weight average molecular weight is 20,
000 anionic group-containing organic polymer compound solutions were obtained.

<Synthesis Example 9> (Synthesis of Organic Polymer Compound A-9 Containing Anionic Group) The monomer composition was changed to 335.1 parts of n-butyl methacrylate,
357.6 parts of n-butyl acrylate, 2-methacrylic acid 2-
150.0 parts of hydroxyethyl, methacrylic acid
3 parts, 2,3-epoxypropyl methacrylate 50.0
The melting parameters were 9.16, the acid value was 70, and the glass transition temperature (calculated value) was 0 in the same manner as in Synthesis Example 2 except that the parts were changed to parts.
An organic polymer compound solution containing an anionic group having a weight average molecular weight of 42,300 was obtained at ℃.

<Synthesis Example 10> (Synthesis of Organic Polymer Compound A-10 Containing Anionic Group) The monomer composition was changed to 6.5 parts of n-butyl methacrylate, 186.6 parts of n-butyl acrylate, and 306.
9 parts, the solubility parameter was 10.37, the acid value was 70,
Glass transition temperature (calculated value) 68 ° C, weight average molecular weight 1
9,600 anionic group-containing organic polymer compound solutions were obtained.

Example 1-A In a mixing vessel equipped with a cooling jacket, 1,000 parts of the anionic group-containing organic polymer compound A-2 solution obtained in Synthesis Example 2 and a 20% aqueous sodium hydroxide solution 210 , 2800 parts of water, and 1,000 parts of Fastgen Blue TGR (CI Pigment Blue 15: 3, manufactured by Dainippon Ink and Chemicals, Inc.) were charged, stirred and mixed. A dispersing device (SC mill SC100 / 32) in which the mixed liquid is filled with zirconia beads having a diameter of 0.3 mm.
, Manufactured by Mitsui Mining Co., Ltd.) and dispersed for 2 hours by a circulation method. The rotation speed of the dispersing device is 2700 rotations / minute,
Cooling water is passed through the cooling jacket and the dispersion temperature is 40 ° C.
It was kept below.

After the dispersion was completed, the undiluted dispersion was taken out of the mixing tank, and then the mixing tank and the dispersing apparatus flow path were washed with 10,000 parts of water. The diluted dispersion was placed in a glass distillation apparatus, and the entire amount of methyl ethyl ketone and a part of water were distilled off to obtain a concentrated dispersion.

After cooling to room temperature, 10% hydrochloric acid was added dropwise to the concentrated dispersion while stirring to adjust the pH to 3.5, and the solid content was filtered with a Nutsche filter and washed with water. The cake is placed in a container, 305 parts of a 20% aqueous potassium hydroxide solution and 200 parts of water are added, and a dispersion stirrer (TK homodisper 20) is added.
Mold, manufactured by Tokushu Kika Kogyo Co., Ltd.). After removing coarse particles with a centrifuge (50A-IV, Sakuma Seisakusho), the nonvolatile content was adjusted to 20%.
A water-based pigment dispersion was obtained.

<Examples 1-B to D> As pigments, Fastgen Super Magenta RTS (CI Pigment Red 122, manufactured by Dainippon Ink and Chemicals, Inc.), Shimla Fast Yellow 4192 (CI Pigment Yellow) 154, manufactured by Dainippon Ink and Chemicals, Inc.) and Monarch 880 (carbon black, manufactured by Cabot)
In the same manner as in Example 1-A, except that was used, an aqueous pigment dispersion having a nonvolatile content of 20% was obtained.

<Examples 2-A to D> As the anionic group-containing organic polymer compound, the anionic group-containing organic polymer compound A-3 obtained in Synthesis Example 3 was used.
210 parts of 0% sodium hydroxide aqueous solution to 330 parts, and 20% aqueous potassium hydroxide solution 30 used for redispersion
An aqueous pigment dispersion having a nonvolatile content of 20% was obtained in the same manner as in Examples 1-A to D, except that 5 parts was changed to 485 parts.

<Examples 3-A to D> As the anionic group-containing organic polymer compound, the anionic group-containing organic polymer compound A-4 obtained in Synthesis Example 4 was used.
210 parts of a 0% aqueous sodium hydroxide solution to 230 parts, and a 20% aqueous potassium hydroxide solution 30 used for redispersion.
An aqueous pigment dispersion having a nonvolatile content of 20% was obtained in the same manner as in Examples 1-A to D except that 5 parts was changed to 315 parts.

<Examples 4-A to D> As the anionic group-containing organic high molecular compound, the anionic group-containing organic high molecular compound A-5 obtained in Synthesis Example 5 was used.
210 parts of a 0% sodium hydroxide aqueous solution to 400 parts, and a 20% potassium hydroxide aqueous solution 30 used for redispersion.
An aqueous pigment dispersion having a nonvolatile content of 20% was obtained in the same manner as in Examples 1-A to D except that 5 parts was changed to 585 parts.

<Examples 5-A to D> As the anionic group-containing organic polymer compound, the anionic group-containing organic polymer compound A-6 obtained in Synthesis Example 6 was used.
210 parts of a 0% sodium hydroxide aqueous solution to 400 parts, and a 20% potassium hydroxide aqueous solution 30 used for redispersion.
An aqueous pigment dispersion having a nonvolatile content of 20% was obtained in the same manner as in Examples 1-A to D except that 5 parts was changed to 585 parts.

<Examples 6-A to 6-D> The anionic group-containing organic polymer compound A-7 obtained in Synthesis Example 7 was used as the anionic group-containing organic polymer compound.
210 parts of a 0% sodium hydroxide aqueous solution to 400 parts, and a 20% potassium hydroxide aqueous solution 30 used for redispersion.
An aqueous pigment dispersion having a nonvolatile content of 20% was obtained in the same manner as in Examples 1-A to D except that 5 parts was changed to 585 parts.

<Examples 7-A to D> The anionic group-containing organic high molecular compound A-8 obtained in Synthesis Example 8 was used as the anionic group-containing organic high molecular compound.
210 parts of a 0% sodium hydroxide aqueous solution to 400 parts, and a 20% potassium hydroxide aqueous solution 30 used for redispersion.
An aqueous pigment dispersion having a nonvolatile content of 20% was obtained in the same manner as in Examples 1-A to D except that 5 parts was changed to 585 parts.

<Example 8-A> In a mixing tank equipped with a cooling jacket, 1,000 parts of the anionic group-containing organic polymer compound A-9 solution obtained in Synthesis Example 9 and a 20% aqueous sodium hydroxide solution 215 were added. Parts, 2800 parts of water, and 1,000 parts of Fastgen Blue TGR (CI Pigment Blue 15: 3, manufactured by Dainippon Ink and Chemicals, Inc.) were charged, stirred and mixed. The mixed liquid is dispersed in a dispersion device (SC mill SC10
0/32, manufactured by Mitsui Mining Co., Ltd.) and dispersed for 2 hours by a circulation method. The rotation speed of the dispersing device is 2700 rotations /
The temperature of the dispersion was kept at 40 ° C. or lower by passing cold water through the cooling jacket.

After the dispersion was completed, the undiluted dispersion was extracted from the mixing tank, and then the mixing tank and the dispersing apparatus flow path were washed with 10,000 parts of water.

The diluted dispersion was placed in a pressure reactor, the vessel was sealed, and the mixture was heated to 140 ° C. for 2 hours with stirring to cause a crosslinking reaction.

The diluted dispersion liquid subjected to the crosslinking reaction was placed in a glass distillation apparatus, and the whole amount of ethyl ethyl ketone and a part of water were distilled off to obtain an aqueous pigment dispersion having a nonvolatile content of 20%.

<Examples 8-B to D> Fastener super magenta RTS (CI Pigment Red 122, manufactured by Dainippon Ink and Chemicals, Inc.), Shimla Fast Yellow 4192 (CI Pigment Yellow) as pigments 154, manufactured by Dainippon Ink and Chemicals, Inc.) and Monarch 880 (carbon black, manufactured by Cabot)
Was used in the same manner as in Example 8-A, except that an aqueous pigment dispersion having a nonvolatile content of 20% was obtained.

Example 9 In a mixing vessel equipped with a cooling jacket, 1,000 parts of the anionic group-containing organic polymer compound A-2 solution obtained in Synthesis Example 2, 210 parts of a 20% aqueous sodium hydroxide solution, 2800 parts of water, Fastgen Blue T
1,000 parts of GR (CI Pigment Blue 15: 3, manufactured by Dainippon Ink and Chemicals, Inc.) were charged, stirred and mixed. The mixed solution was passed through a dispersing apparatus (SC Mill SC100 / 32, manufactured by Mitsui Mining Co., Ltd.) filled with zirconia beads having a diameter of 0.3 mm, and dispersed for 2 hours by a circulation method. The rotation speed of the dispersing device was set to 2700 rpm, and the temperature of the dispersion liquid was kept at 40 ° C. or lower by passing cold water through a cooling jacket.

After the dispersion was completed, the undiluted dispersion was extracted from the mixing tank, and then the mixing tank and the dispersing apparatus channel were washed with 10,000 parts of water.

The diluted dispersion was put into a glass distillation apparatus, and the entire amount of methyl ethyl ketone and a part of water were distilled off. After cooling to room temperature, coarse particles were removed with a centrifugal separator (Model 50A-IV, Sakuma Seisakusho), and the nonvolatile content was adjusted to obtain an aqueous pigment dispersion having a nonvolatile content of 20%.

<Examples 9-B to D> As pigments, Fastgen Super Magenta RTS (CI Pigment Red 122, manufactured by Dainippon Ink and Chemicals, Inc.), Shimla Fast Yellow 4192 (CI Pigment Yellow) 154, manufactured by Dainippon Ink and Chemicals, Inc.) and Monarch 880 (carbon black, manufactured by Cabot)
In the same manner as in Example 9-A, except that was used, an aqueous pigment dispersion having a nonvolatile content of 20% was obtained.

<Comparative Examples 1-A to D> [0098] Except that 1,000 parts of the anionic group-containing organic polymer compound A-1 solution obtained in Synthesis Example 1 was used as the anionic group-containing organic polymer compound. Non-volatile content 20% in the same manner as in Examples 1-A to D
A water-based pigment dispersion was obtained.

<Comparative Examples 2-A to D> Except that 1,000 parts of the anionic group-containing organic polymer compound A-10 solution obtained in Synthesis Example 10 was used as the anionic group-containing organic polymer compound. Non-volatile content 2 in the same manner as in Examples 1-A to D
A 0% aqueous pigment dispersion was obtained.

<Example 10> (Evaluation of aptitude of aqueous recording liquid for thermal ink jet printer) The aqueous pigment dispersions obtained in Examples 1 to 9 and Comparative Examples 1 and 2 were described in JP-A-6-122846. The ink for a thermal inkjet printer was prepared with reference to Example 2 of Example 1. The ink composition is shown below.

Aqueous pigment dispersion 25 parts Glycerin 8 parts Ethylene glycol 5 parts Ethanol 5 parts Emulgen 120 (manufactured by Kao Corporation) 0.05 parts Water 57 parts

The average particle size of the ink thus prepared was measured. The average particle diameter was defined as the median diameter measured with a laser Doppler particle size analyzer Microtrac (UPA150, manufactured by Leeds & Northrop).

As a stability evaluation, the magenta ink was subjected to a storage test at 70 ° C. for 5 days, and the change in average particle diameter was examined. Further, 100 sheets of continuous printing were performed on the cyan ink with a thermal inkjet printer (BJC-600J type, manufactured by Canon Inc.), and the printing performance was evaluated. The results are shown in the table.

[0104]

[Table 1] Table

<Note> Stability ：: Change in average particle size is less than 5% △: 〃 5% or more and less than 20% ×: ２０ 20% or more Printability ：: 50 or more sheets can be printed △: 10 to less than 50 sheets Blurring and the like occur. ×: Blurring and the like occur in less than 10 sheets.

TGR, RTS, 4192 and 8 in the table
80 is the above-mentioned Fastogen Blue TG in order, respectively.
R, Fastgen Super Magenta RTS, Shimla Fast Yellow 4192 and Monarch 880.

The following can be seen from the above table. -When a yellow pigment or a black pigment is used, a resin outside the solubility parameter range gives microcapsules having a larger initial particle size than the resin within the range (Example 1 and Comparative Examples 1 and 2). -When a red pigment is used, a resin within the solubility parameter range gives a microcapsule having a small change in particle size and excellent stability than a resin outside the range (Example 1 and Comparative Examples 1 and 2). When using a red pigment or a blue pigment, acid precipitation gives microcapsules having a smaller initial particle diameter than acid precipitation (Examples 1 and 9). -When a blue pigment is used, microcapsules having a smaller initial particle size are obtained when crosslinked is not crosslinked (Examples 1 and 8). -When a red pigment is used, microcapsules having a smaller initial particle size are obtained by including styrene as a comonomer than by not including styrene (Examples 1 and 2). When using a red pigment, rather than not including styrene,
The inclusion gives microcapsules with small particle size change and excellent stability (Examples 1 and 2).

[0108]

The aqueous pigment dispersion of the present invention uses an anionic group-containing organic polymer compound having a solubility parameter in a specific range. Than when using
An aqueous pigment dispersion having a smaller initial particle size or a smaller change over time in particle size can be obtained, and excellent dispersibility and dispersion stability can be obtained. as a result,
When used in a recording liquid such as an ink for an ink jet printer, a recording liquid having excellent storage stability, color rendering properties, and transparency can be provided, and a clear image can be formed.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F070 AA18 AA27 AA29 AA32 AA37 AB21 AC04 AC31 AE04 CA02 CB01 4J037 AA02 AA30 CC13 CC16 CC30 DD23 DD24 EE03 EE28 EE43 FF06 FF07 FF15 FF22 FF25 4J039 AD03 AD09 AD09 AD09 AD09 EA38 EA44 GA24 GA26

Claims (5)

[Claims] 1. An aqueous pigment dispersion containing at least a pigment and an anionic group-containing organic polymer compound,
An aqueous pigment dispersion, wherein an organic polymer compound having an anionic group having a solubility parameter of 9.0 to 10.0 is used as the organic polymer compound having an anionic group. 2. An organic polymer compound having an anionic group,
At least 3 carbon atoms of acrylic acid and methacrylic acid
The aqueous pigment dispersion according to claim 1, wherein the aqueous pigment dispersion is an anionic group-containing organic polymer compound containing, as a constituent element, at least one compound selected from the group consisting of alkyl esters of No. 5. 3. An organic polymer compound having an anionic group,
At least 3 carbon atoms of acrylic acid and methacrylic acid
The aqueous pigment dispersion according to claim 1, wherein the aqueous pigment dispersion is an anionic group-containing organic polymer compound containing, as constituents, one or more compounds selected from the group consisting of alkyl esters of 5 and styrene. 4. The aqueous pigment dispersion according to claim 1, wherein the pigment is coated with an anionic group-containing organic polymer compound. 5. An aqueous recording liquid comprising the aqueous pigment dispersion according to claim 1.