JPH0940895A - Microcapsule ink composition for ink jet recording and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition excellent in colorability, light resistance, stably dispersible finely for a long period of time. SOLUTION: Colored resin particles (microcapsule) containing a pigment of an achromatic color such as carbon black, silica, etc., are dispersed into an aqueous medium by a self-water-dispersible resin dyed by a dye such as a self-water-dispersible dyed resin obtained by neutralizing >=60mol % of an acid group of a styrene (meth)acrylic acid copolymer having >=50 and <=280 acid value to give the objective microcapsule ink composition for ink jet recording.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a microcapsule ink composition for ink jet recording and a method for producing the same, and more specifically to a colored resin particle in which an achromatic pigment is encapsulated by a self-water-dispersible resin dyed with a dye. The present invention relates to a microcapsule ink composition for inkjet recording, which comprises as a microcapsule component, and a method for producing the same.

[0002]

2. Description of the Related Art Among conventional inks for ink jet recording, dye inks can obtain high color development, but they have drawbacks such as poor water resistance / light resistance and large blurring of characters in printing. On the other hand, the pigment ink has good water resistance, light resistance, and bleeding of characters, but has a drawback that color development is worse than that of the dye ink. Further, since the pigment used in the black ink is generally carbon black, it is unavoidable that it has a slightly reddish hue.

In order to solve the above drawbacks, it has been proposed to color the polymer particles with a dye. As a specific example, in JP-A-58-45272, an ink composition containing a urethane polymer latex containing a dye is proposed. Stuff,
In JP-A-62-95366, a polymer and an oil dye are dissolved in a water-insoluble organic solvent, further mixed with an aqueous solution containing a surfactant to emulsify, and then the solvent is evaporated to be encapsulated in polymer particles. A method for preparing an inkjet composition containing a dye has been proposed. However, since there is no core material, it is difficult to obtain colored particles that are fine particles and have excellent dispersion stability. Further, since the polymer is colored with a dye, it is not always excellent in light resistance.

On the other hand, Japanese Patent Laid-Open No. 3-160069 proposes an image recording ink in which a dye or a pigment is adsorbed on the surface of emulsion particles. However, there are many unadsorbed dyes and pigments which are caused by dyes and pigments such as bleed. Deterioration in characteristics was unavoidable.

[0005]

The problem to be solved by the present invention is to provide a microcapsule ink composition for ink jet recording which is excellent in color developability and light fastness and which is fine particles and excellent in dispersion stability. .

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have accomplished the present invention.

That is, according to the present invention, colored resin particles (B) in which an achromatic pigment is encapsulated by a self-water-dispersible resin (A) dyed with a dye are dispersed in an aqueous medium (C) containing water as an essential component. Another object is to provide a microcapsule ink composition for inkjet recording, which is characterized by being dispersed.

The present invention also provides a synthetic resin (1) having an acid group, which can be self-dispersed in water by neutralization, a base (2) capable of neutralizing the acid group, a dye (3), and an achromatic pigment (4). And a self-water-dispersible colored resin solution obtained by mixing at least a part of acid groups of the resin (1) obtained by mixing the organic solvent (5) in the presence of water, and water as an essential component. Mixed with an aqueous medium (C) for phase inversion emulsification to obtain colored resin particles (B) containing achromatic pigment (4) in self-water dispersible resin (A) dyed with dye (3). Another object of the present invention is to provide a method for producing a microcapsule ink composition for inkjet recording, which comprises dispersing in an aqueous medium (C) and then removing the organic solvent (5) from the obtained aqueous dispersion.

In the present invention, the self-water dispersible resin (A) forming the microcapsules, that is, the shell material resin of the so-called microcapsules, exhibits self-water dispersibility by neutralization.
In the synthetic resin (1) having an acid group, a self-water-dispersible resin in which at least a part of the acid group is neutralized with a base (2) is used. Such a resin is preferable because it wets well with an achromatic pigment and has good compatibility with a dye.

The acid group possessed by the synthetic resin (1) is not particularly limited and may be a carboxylic acid group, a sulfonic acid group, a sulfinic acid group, etc. Among them, the carboxylic acid group is generally used.

The acid value of the synthetic resin (1) is 50 or more and 280.
The following is preferred. When the acid value of the synthetic resin (1) is less than 50, the aqueous dispersion stability of the obtained colored resin particles is not sufficient,
When the acid value exceeds 280, aggregation tends to occur during neutralization of the water-dispersible resin dissolved in an organic solvent with a base,
In addition, since some of the resin dissolves when added to water, nozzle clogging is likely to occur.
The acid value of (1) is in the range of 50 or more and 280 or less, preferably 70 to 250.

As such a synthetic resin (1), a vinyl copolymer having a carboxylic acid group is preferable, for example, styrene or substituted styrene such as α-methylstyrene, acrylic acid methyl ester, acrylic acid ethyl ester,
At least one or more selected from acrylic acid butyl ester, acrylic acid 2-ethylhexyl ester and other acrylic acid esters, methacrylic acid methyl ester, methacrylic acid ethyl ester, methacrylic acid butyl ester, methacrylic acid 2-ethylhexyl and other methacrylic acid esters. A vinyl copolymer containing a monomer unit and at least one or more monomer units selected from acrylic acid and methacrylic acid is preferable, and more preferably a vinyl copolymer using a styrene monomer, an acrylic acid monomer, or a methacrylic acid monomer as an essential monomer component. It is a polymer.
The vinyl copolymer using these monomers does not have a group such as an ester bond which is easily separated by light, heat, solvent or the like in its molecular structure, and thus can be said to be an extremely stable resin. In particular, the constituent ratio of these essential monomer components is 60 to 90 mol% of styrene monomer and 5 of acrylic acid monomer.
~ 15 mol%, methacrylic acid monomer 5-25 mol%
In that case, excellent colored resin particles (colored microcapsule particles) without nozzle clogging can be used for inkjet recording.

The molecular weight range of the above-mentioned synthetic resin (1) is not particularly limited, but one having a molecular weight of 1,000 or more and 100,000 or less is more preferable. Of course, the resin (1) is not particularly limited as long as it forms stable microcapsules when combined with the aqueous medium (C) described later, and two or more kinds of them are mixed and used at the same time. You may.

Further, even if the glass transition temperature of the synthetic resin (1) is less than 50 ° C., the fixability of characters after printing on recording paper is good, but nozzle clogging and storage stability are further enhanced. Considering this, a glass transition temperature of preferably 50 ° C. or higher, more preferably 60 ° C. or higher is suitable for inkjet recording.

Neutralization with the base (2), that is, neutralization with an alkaline neutralizing agent, is necessary to neutralize the synthetic resin (1) to such an extent that it does not dissolve in water.
May be added in excess. It is preferable to neutralize 60 mol% or more of the acid groups of the synthetic resin (1). When the neutralization rate is 60 mol% or more, the obtained colored resin particles (B) are fine particles and have excellent dispersion stability.

The content of the self-water-dispersible resin (A) in the aqueous medium (C) is not particularly limited as long as the effects of the present invention are achieved, but in the finally obtained aqueous ink composition. The amount is preferably 0.5 to 20% by weight.

Examples of the base (2) include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, basic substances such as ammonia, triethylamine and morpholine, and especially triethanolamine and diethanolamine. , N-methyldiethanolamine and other alcohol amines can be used, but the use of alcohol amine is particularly preferable. Being an alcohol amine,
It is possible to obtain an ink for inkjet recording which is more excellent in the dispersion stability of the colored resin particles (B) and has improved nozzle clogging due to particle aggregation due to evaporation of water or an organic solvent.

Synthetic resin having an acid group used in the present invention
As a method of neutralizing by adding the base (2) related to (1),
There are methods such as adding in advance to a solution of the synthetic resin (1) in an organic solvent, or adding to the aqueous medium when the organic solvent solution of the synthetic resin (1) and the aqueous medium (C) are mixed. For the adoption, the best condition may be selected.

On the other hand, the pigments used in the present invention are achromatic pigments, such as black pigments and white pigments, and black pigments such as carbon black.
As the white pigment, in addition to titanium white, extender pigments such as silica, zinc oxide and alumina are included in the present invention. The above-mentioned white pigment is generally used as it is, but if necessary, it may be used in the form of a color pigment in which a dye is adsorbed on the surface of the white pigment.

The dye is not particularly limited, but a dye soluble in an organic solvent is preferable. Representative examples include azo dyes such as monoazo and disazo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoimine dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes. Examples thereof include naphthalimide dyes, perinone dyes, phthalocyanine dyes, triallylmethane dyes, and the like, but are not limited to these examples. These dyes may be present in a partially dispersed form, but it is preferable to select one that is soluble in the shell resin forming the microcapsules.

In the microcapsules of the present invention, these achromatic pigments / dyes are present as colored resin particles in which the achromatic pigment is encapsulated by the self-water-dispersible resin dyed with the dye. These colored resin particles (colored microcapsule particles) are excellent in dispersion stability, and also have effects such as good water resistance and light resistance, no blurring of characters, and good color development. Furthermore, it shows various usefulness in terms of color.

For example, unlike coloring different pigments, particles of different colors are rarely mixed so that there is no color separation in the printed matter, and the pigment alone has an effect of improving the color developability as compared with the color that tends to sink. Dyes alone have poor light fastness, but the combined use of pigments has the advantage that the light fastness is greatly improved due to the ultraviolet light scattering / absorption effect. Furthermore,
When the achromatic pigment of the core material is an extender pigment having a small refractive index such as silica or alumina, the transparency is high, and a transparent and bright color is obtained by the self-water-dispersible resin dyed with the dye. A white pigment having a large refractive index, such as titanium white, has the advantage that a self-water-dispersible resin dyed with a dye can produce a bright and highly concealable color.
On the other hand, when the core material is carbon black, which is a black pigment, the main purpose of dyeing with a dye is toning. In particular, when the pigment is carbon black and the dye is a black dye and / or a blue dye in combination, it is possible to reproduce a high-grade jet black hue which is not present in conventional carbon black.

The total amount of the dye and achromatic pigment used in the present invention is not particularly limited as long as the effect of the present invention is achieved, but it is 0.5 in the finally obtained water-based ink.
The amount is preferably about 20% by weight. In order to achieve the effect of the present invention, the weight ratio of the dye to the achromatic pigment is preferably in the range of 1% by weight to 50% by weight.

The colored microcapsules of the present invention are
The achromatic pigment is microencapsulated at the same time as the dye is dyed with the dye, the resin is dyed with the dye and then the pigment is microencapsulated, and the resin particles (microcapsule particles) containing the pigment are dyed with the dye. It is formed by means such as dyeing.

The composition of the present invention containing the formed colored microcapsule component, that is, the ink jet ink of the present invention in which the colored microcapsules in which the achromatic pigment is encapsulated by the self-water dispersible resin dyed with a dye are dispersed in an aqueous medium. The recording composition, for example, a dye and an achromatic pigment are added to an organic solvent solution of a synthetic resin (1), dissolved and dispersed by using a stirrer or a dispersing device and well mixed, and then the presence of the base (2). It can be prepared by mixing it with an aqueous solvent (C) below.

More specifically, the microcapsule ink composition for ink jet recording of the present invention can be easily produced by preparing it by a microencapsulation method generally called a phase inversion emulsification method. In the production by the phase inversion emulsification method, basically, the first step is to dissolve the synthetic resin (1) in an organic solvent, which is soluble in an organic solvent and self-dispersible by neutralization. The step of dispersing and dissolving in a resin solution (mill base step), the second step is to mix the solution with an excess amount of an aqueous medium in the presence of a base (2), whereby the dye disperses the water-dispersible resin. The process comprises the step of obtaining resin particles encapsulating an achromatic pigment (encapsulation step), and in some cases, as a third step,
A step of removing the organic solvent used in the first-stage mill base step (solvent removal step) may be included.

In the production of the above-mentioned microcapsule ink composition, both the dye and the achromatic pigment are preferably dispersed or dissolved in a self-water-dispersible resin before being dispersed in an aqueous medium.

When encapsulating using the phase inversion emulsification method, the organic solvent used in the first step is a ketone solvent such as acetone, dimethyl ketone, methyl ethyl ketone;
Alcohol solvents such as methanol, ethanol and isopropyl alcohol; ether solvents such as tetrahydrofuran and dioxane; chlorine solvents such as chloroform and methylene chloride; aromatic solvents such as benzene and toluene; ester solvents such as ethyl acetate. Glycol ether solvents such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether; amides and the like can be used as long as they dissolve the resin, but in the case of the phase inversion emulsification method using the synthetic resin (1), a ketone A combination of at least one selected from a system solvent and an alcohol solvent gives good microcapsules, and this combination is preferable.

In the present invention, additives such as a dispersant, a plasticizer, an antioxidant and an ultraviolet absorber may be used together with an organic solvent, a resin and a dye / pigment, if necessary. In the second stage encapsulation, the resin and the dye / achromatic pigment are mixed with the above solvent and dissolved / dispersed by using a stirrer or a dispersion device, and the obtained organic solvent solution and water are the aqueous medium containing the essential components. This is done by mixing and.

In the second stage microencapsulation, the first
In the presence of the base (2) in the millbase obtained in the step, water or an aqueous solution is mixed to perform encapsulation, but depending on the achromatic pigment or dye used, loose aggregation of the capsules may occur, so encapsulation occurs. It is preferable to add water or an aqueous solution afterwards to carry out mixing and dispersion. In this step, in an aqueous medium containing water as an essential component, a coloring solution containing a self-water-dispersible resin may be added, but on the contrary, adding an aqueous medium to a coloring solution containing the resin provides uniform particles. It is preferable in that an aqueous dispersion having a diameter can be obtained. If necessary, a surfactant may be used in combination, and the emulsion may be forcibly emulsified. However, it is preferable not to use a surfactant or protective colloid because it tends to deteriorate the physical properties of the finally obtained particles.

The base (2) is added to the millbase or aqueous solution. The water used in the aqueous medium is preferably ion-exchanged water or higher grade. As a third step, after the encapsulation is completed, a desolvation step of removing the organic solvent that dissolves the synthetic resin (1) used in the first mill-base step is performed to suppress the swelling / aggregation of the colored microcapsules. A stable and stable aqueous dispersion is obtained, which is suitable for an aqueous ink for inkjet recording. If necessary, water may be removed in this desolvation step. Also, of course,
This third stage process may be omitted in some cases.

In order to put the composition of the present invention containing colored microcapsules into practical use as an ink composition for ink jet recording, it is preferable to use a water-soluble organic solvent as an additive for preventing drying. As the anti-drying agent, polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, glycerin, etc. or alkyl ethers thereof, N-methyl-2-pyrrolidone, which are conventionally known, Examples thereof include pyrrolidones such as 2-pyrrolidone, amides, dimethyl sulfoxide, imidazolidinone, and the like, but are not limited thereto.

If necessary, a water-soluble organic solvent for imparting permeability may be added, and lower alcohols such as ethanol and isopropyl alcohol, glycol ethers such as diethylene glycol-N-butyl ether and the like can be used. It is not limited to. In addition, additives such as a water-soluble resin, a pH adjuster, a surfactant for dispersion / defoaming / penetration into paper, an antiseptic, a chelating agent and the like can be added if necessary.

These additives can be added in any suitable process from the first stage to the final stage, but it is preferable to avoid adding the additives after the final filtration. After the final composition adjustment is completed, it is preferable to remove large-sized particles by filter filtration, centrifugation, etc. to obtain the aqueous ink of the present invention.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described below by taking as an example a case where it is produced by a phase inversion emulsification method.

As the synthetic resin, at least one monomer selected from the group consisting of styrene, substituted styrene, and (meth) acrylic acid ester, and (meth) acrylic acid are obtained by copolymerization, and the acid value is 50 or more and 280. Hereinafter, a synthetic resin solution prepared by dissolving a vinyl copolymer having a molecular weight of 1,000 or more and 100,000 or less in an organic solvent, an achromatic pigment, and a dye soluble in the synthetic resin as a dye are mixed and kneaded to form a colored mill base. obtain. The weight ratio of the dye to the pigment is in the range of 1% by weight to 50% by weight. A base capable of neutralizing the acid group of the synthetic resin is added to this colored mill base, and the mixture is stirred and mixed, and further, an aqueous medium containing water is added dropwise with stirring and mixed to perform phase inversion emulsification, whereby the dye is dyed. An aqueous dispersion of colored microcapsules in which colored resin particles in which an achromatic pigment is encapsulated by the self-water-dispersible resin are dispersed in an aqueous medium are obtained. At this time, the addition amount of the base as the alkali neutralizing agent is in the range of neutralizing 60 mol% or more of the acid groups. When the achromatic pigment or dye used causes loose agglomeration of the capsules, water or an aqueous solution is additionally mixed and redispersed after the encapsulation. Furthermore, the organic solvent used for dissolving the synthetic resin is removed by vacuum distillation to obtain an ink composition for inkjet recording.

[0037]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following examples, "part" means "part by weight".

Example 1 Carbon black 20 parts Styrene acrylate resin 20 parts (Styrene / 2-ethylhexyl acrylate / acrylic acid = 77/10/13; acid value 100, molecular weight 40,000) Oily phthalocyanine dye 2 Parts 49 parts of methyl ethyl ketone was kneaded for 4 hours with a paint shaker using glass beads having a diameter of 0.2 mm, 40 parts of methyl ethyl ketone and 40 parts of isopropyl alcohol were added, and the contents were taken out to obtain 171 parts of a mill base solution.

To 171 parts of the mill base, 5.3 parts of triethanolamine (corresponding to a resin neutralization ratio of 100%) was added and stirred while 50 parts of glycerin and 120 parts of ion-exchanged water were added.
Part of the mixed solution was added dropwise at a rate of 5 ml per minute to obtain a colored microcapsule composition. The obtained colored microcapsule composition was subjected to a dispersion treatment again using a collision type dispersion device Nanomizer (manufactured by Nanomizer Co., Ltd.) at a pressure of 1500 kg / cm ² . A mixture of 80 parts of glycerin and 300 parts of ion-exchanged water was added dropwise to the obtained treatment liquid at a rate of 5 ml / min, and then methyl ethyl ketone and isopropyl alcohol were distilled off by using a rotary evaporator to finally disperse the colored microcapsules in water. I got a thing.

This aqueous dispersion was filtered using a 1.5 μm filter to obtain a microcapsule ink for ink jet recording. The microcapsules in the obtained ink had an average particle size of 0.1 μm, showed stable dispersion for a long time without aggregates, and printing using an inkjet printer was stable. Had a jet black color tone, had no bleeding, and was excellent in water resistance and light resistance.

Comparative Example 1 A microcapsule ink for ink jet recording was obtained in the same manner as in Example 1 except that the oily phthalocyanine dye was removed from the mill base. The obtained printed matter was slightly brownish and could not be said to have a good color tone.

Example 2 Colloidal silica 2 parts Styrene acrylic acid resin 40 parts (styrene / 2-ethylhexyl acrylate / acrylic acid / methacrylic acid = 72/5/10/13; acid value 15
5, molecular weight 45,000) Oily magenta dye 4 parts Methyl ethyl ketone 50 parts Glass beads 150 parts Blended for 4 hours with a paint shaker, methyl ethyl ketone 40 parts Isopropyl alcohol 40 parts was added and the contents were taken out, and the mill base solution was added. 176 parts were obtained.

16.5 parts of triethanolamine (corresponding to a resin neutralization ratio of 100%) was added to 176 parts of the mill base, and 65 parts of glycerin and 21 parts of ion-exchanged water were added with stirring.
0 part of the mixed solution was added dropwise at a rate of 5 ml per minute to obtain a colored microcapsule composition.

The obtained colored microcapsule liquid was subjected to a dispersion treatment again using a collision type dispersion device Nanomizer (manufactured by Nanomizer Co., Ltd.) at a pressure of 1500 kg / cm ² . A mixture of 75 parts of glycerin and 210 parts of ion-exchanged water was added dropwise to the obtained treatment liquid at a rate of 5 ml / min, and then methyl ethyl ketone and isopropyl alcohol were distilled off using a rotary evaporator to obtain a final aqueous dispersion of colored microcapsules. Got

This aqueous dispersion was filtered using a 1.5 m filter to obtain a microcapsule ink composition for inkjet recording. The microcapsules in the obtained ink had an average particle size of 0.086 μm, showed stable dispersion for a long period without aggregates, and printing using an inkjet printer was stable, and the obtained printed matter was obtained. Had a bright magenta color tone, had no bleeding, and was excellent in water resistance and light resistance.

(Comparative Example 2) Styrene acrylic acid resin 40 parts (styrene / 2-ethylhexyl acrylate / acrylic acid / methacrylic acid = 72/5/10/13; acid value 15
5, molecular weight 45,000) Oily magenta dye 4 parts Methyl ethyl ketone 90 parts Isopropyl alcohol 40 parts The composition of Example 2 except colloidal silica was dissolved with a stirrer to obtain 174 parts of a mill base solution.

To 174 parts of the mill base, 16.5 parts of triethanolamine (corresponding to a resin neutralization ratio of 100%) was added and stirred with 65 parts of glycerin and 21 parts of ion-exchanged water.
0 part of the mixed solution was added dropwise at a rate of 5 ml per minute to obtain a colored resin emulsion.

The obtained colored resin emulsion was subjected to dispersion treatment again using a collision type dispersion device Nanomizer (manufactured by Nanomizer Co., Ltd.) at a pressure of 1500 kg / cm ² . A mixture of 75 parts of glycerin and 210 parts of ion-exchanged water was added dropwise to the obtained treatment liquid at a rate of 5 ml / min, and then methyl ethyl ketone and isopropyl alcohol were distilled off using a rotary evaporator to obtain a final colored resin emulsion. It was This colored resin emulsion could not be filtered even with a 5 m filter, and a microcapsule ink composition for inkjet recording could not be obtained. 0.22 for colored resin emulsion
Although it had an average particle size of μm, about 2% of coarse particles of 1 μm or more were present.

(Example 3) Instead of the styrene acrylic resin of Example 2, a styrene acrylic resin (styrene / acrylic acid / methacrylic acid = 65/10/25; acid value 22)
1, the molecular weight is 45,000), and the neutralization rate of the resin is 1
A microcapsule ink composition for inkjet recording was prepared in the same manner as in Example 2 except that triethanolamine was used in an amount corresponding to 00%. The microcapsules in the obtained ink had an average particle size of 0.060 μm, showed stable dispersion for a long time without aggregates, and the printing using an inkjet printer was stable. Had a bright magenta color tone, had no bleeding, and was excellent in water resistance and light resistance.

[0050]

The microcapsule ink composition for inkjet recording of the present invention in which the colored resin particles containing the achromatic pigment in the self-water dispersible resin dyed with the dye are dispersed in the aqueous medium (C) are excellent. It has color developability and light resistance, and enables stable dispersion over a long period of time.

Claims (14)

[Claims] 1. A self-water-dispersible resin (A) dyed with a dye.
Resin particles (B) containing an achromatic pigment
Is dispersed in an aqueous medium (C) containing water as an essential component, the microcapsule ink composition for inkjet recording. 2. The achromatic pigment is a white pigment.
The microcapsule ink composition for inkjet recording as described above. 3. The white pigment is titanium white, silica,
The microcapsule ink composition for inkjet recording according to claim 2, which is at least one selected from zinc oxide and alumina. 4. The microcapsule ink composition for inkjet recording according to claim 1, wherein the achromatic pigment is carbon black. 5. The microcapsule ink composition for inkjet recording according to claim 4, wherein the pigment is carbon black and the dye is a black dye and / or a blue dye. 6. The weight ratio of the dye to the pigment is 1% to.
The microcapsule ink composition for inkjet recording according to claim 1 or 5, which is in a range of 50%. 7. The self-water-dispersible resin (A) is a self-water-dispersible resin obtained by neutralizing at least a part of acid groups of a synthetic resin (1) having an acid group with a base (2). 1. The water-based ink for inkjet recording according to 1. 8. The water-based ink for ink jet recording according to claim 7, wherein the synthetic resin (1) is a vinyl copolymer having a carboxylic acid group. 9. The synthetic resin (1) is a vinyl copolymer of (meth) acrylic acid and at least one monomer selected from the group consisting of styrene, substituted styrene and (meth) acrylic acid ester. 8. The water-based ink for inkjet recording according to item 8. 10. The microcapsule ink composition for inkjet recording according to claim 7, wherein the base (2) is an alcohol amine. 11. A synthetic resin (1) having an acid group capable of self-dispersing in water by neutralization, a base (2) capable of neutralizing the acid group, a dye (3) and an achromatic pigment (4). Self-water-dispersible colored resin solution obtained by neutralizing at least a part of acid groups of the resin (1) obtained by mixing in the presence of an organic solvent (5), and an aqueous medium containing water as an essential component. (C) is mixed to perform phase inversion emulsification, and a dye
Achromatic pigment with self-water dispersible resin (A) dyed with (3) (4)
The colored resin particles (B) encapsulating the above are dispersed in an aqueous medium (C), and then the obtained aqueous dispersion is used to prepare the organic solvent.
A method for producing a microcapsule ink composition for inkjet recording, which comprises removing (5). 12. The method for producing an aqueous ink for inkjet recording according to claim 11, wherein the synthetic resin (1) is a vinyl copolymer having a carboxylic acid group. 13. The synthetic resin (1) is a vinyl copolymer of (meth) acrylic acid and at least one monomer selected from the group consisting of styrene, substituted styrene and (meth) acrylic acid ester. 13. The method for producing a water-based ink for inkjet recording according to item 12. 14. The method for producing a microcapsule ink composition for inkjet recording according to claim 11, wherein the base (2) is alcohol amine.