JPH01115976A - Aqueous pigment dispersion - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a colorant or a colorant-containing composition that does not have a single color separation and is used for writing ink, printing ink, paint, etc. It is something.

More specifically, by encapsulating two or more pigments in the same capsule, they exhibit the same behavior as a single pigment particle, providing a uniform coloring agent that cannot be obtained simply by combining individual pigments.

(Prior art) As a coloring agent for writing ink, printing ink, paint, etc.
Organic pigments and inorganic pigments have been used, and are dispersed in water using a resin face such as an aqueous resin dispersion or an aqueous resin solution, or a surfactant.

Although a pigment may be used alone, it is also common to use two or more pigments in combination. For example, combinations of organic pigments and inorganic pigments, combinations of organic pigments, inorganic pigments, and extender pigments, etc. In particular, when mixing an organic pigment 2 such as phthalocyanine blue and an inorganic pigment 9 such as titanium white,
It is a useful combination because it is a light color and maintains strong fastness.

However, the characteristics of each of the pigments used in combination2 particle size.

Due to differences in surface potential, a separation phenomenon called 9-color separation or color floating occurs even in the dispersed state and in the final applications such as writing ink, printing ink, and paint, and a great deal of energy has been spent on countermeasures.

(Problems to be Solved by the Invention) The present invention exhibits the same behavior as a single pigment by encapsulating two or more types of pigments in the same capsule, and eliminates the phenomenon of color separation and two-color floating. This is an aqueous pigment dispersion designed to prevent

[Structure of the invention]

(Means for Solving the Problem) The present invention provides a core material for an oil-based pigment dispersion containing two or more pigments, a resin, and an organic solvent for dissolving the resin.

This is an aqueous pigment dispersion that is encapsulated in a shell formed by interfacial polymerization and mixed with an aqueous resin dispersion or an aqueous water-soluble resin solution as necessary. Furthermore, the capsule is 0
．． It is an aqueous pigment dispersion having a particle size of 2 to 10 μm.

The core material in the present invention includes two or more pigments.

It is an oil-based pigment dispersion containing a resin and an organic solvent for dissolving the resin. The oil-based pigment dispersion may also contain dyes, additives, and the like.

Pigments have traditionally been used in writing inks, printing inks,
Pigments used in paints, recording materials, etc. are used.

For example, zinc yellow, yellow iron oxide, Hansa yellow, disazo yellow, quinoline yellow, permanent yellow, permanent red, red red, Lissol red, Wosochang red Ca salt, Wosochang red Mn salt,
Pyrazolone Red, Lake Sod C, Lake Kid D,
Brilliant Carmine 6B, Brilliant Carmine 3B
, dark blue, phthalocyanine blue, metal-free phthalocyanine, titanium oxide, carbon black, etc.

Preferably, the resin has the ability to disperse pigments well.1For example, ethylene-vinyl acetate copolymer, polysterene, styrene with styrene and acrylic ester, meccrylic ester, acrylonitrile, maleic ester, etc. Including copolymer systems, polyacrylic ester systems, polymethacrylic ester systems, polyester systems, polyamide systems, polyvinyl acetate systems, epoxy systems, phenolic systems, and hydrocarbon systems.

Examples include rosin, rosin-modified resin 2, petroleum-based resins, and these can be used alone or in combination.

The solvent is preferably one that dissolves or swells the resin, and even a solvent that does not dissolve the resin can be used as part of the solvent.

Examples of solvents include phthalate esters, phosphate esters, fatty acid esters, benzoate esters, citric esters, diarylalkanes, alkylphenyl ethers, polybutene, vegetable oil, and toluene.

Hydrocarbon solvents such as xylene can be used.

Note that the core material of the present invention may contain various additives, if desired.2 For example, various waxes, silicon compounds, etc. can be mentioned.

The above-mentioned core substance is obtained by heating or cooling the R material, resin, solvent, other additives, etc. in a dispersing machine such as a ball mill, attritor, dyno mill, or three-roll mill as necessary to disperse them.

In the present invention, interfacial polymerization is carried out by dissolving and dispersing a hydrophobic polymerizable compound in the core material, mixing and stirring with an aqueous medium containing a dispersion stabilizer, and emulsifying it. Polymerization is carried out with a hydrophobic polymerizable compound.

Examples of the hydrophobic polymerizable compounds include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and knuc diisocyanate.
Dimethoxybiphenyl diisocyanate, dimethyldiphenylmethane diisocyanate, xylylene diisocyanate, diphenylpropane diisocyanate, trimethylene diisocyanate hexamethylene diisocyanate, propylene diisocyanate.

Butylene diisocyanate, ethyridine diisocyanate cyclohexylene diisocyanate, tolylene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenylisocyanate.

Dimethyldiphenylmethane tetraisocyanate, polyisocyanate prepolymer, tetramethylene diisothiocyanate, hexamethylene diisothiocyanate, p-phenylene diisothiocyanate, xylene-1
, urethane-based and urea resin-based shell-forming compounds such as 4-diisothiocyanate ethyridine diisocyanate,
Epoxy shell-forming compounds commercially available under trade names such as Epicote, oxazoloyl chloride, succinoyl chloride, adipoyl chloride, sebacoyl chloride, phthaloyl chloride, isophthaloyl chloride, fumaroyl chloride, Cyclohexane dicarbonyl chloride polyester with chloride group, polyamide, benzenedisulfonyl chloride, naphthalene disulfonyl chloride, oxybisbenzenedisulfonyl chloride, hexane disulfonyl chloride, ethylene bis(chloroformate), tetramethylene bis( chloroformate), 2,2'-dimethyl-
Polyamide shell-forming compounds such as 1,3-propane bis(chloroformate) and p-propane bis(chloroformate) are used, and these can be used alone or in combination of two or more.

These compounds can be added when preparing a dissolved dispersion of the core substance, but they can also be added when producing a dissolved dispersion of the core substance.
It is preferable to add it to the dissolved dispersion of the core substance immediately before mixing and stirring with water containing a dispersion stabilizer. The above-mentioned core material and polymerizable compound are mixed together in a dispersion liquid.

Mix and stir with an aqueous medium containing a dispersion stabilizer.

Dispersion stabilizers include polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose, cellulose gum, silica fine powder,
These include water-soluble polymer compounds such as sodium lauryl sulfate and sodium oleate, metal oxides, anionic surfactants, nonionic surfactants, and cationic surfactants. These dispersion stabilizers have the effect of making each particle smaller and making the particle size more uniform.

Mixing and stirring is carried out by adding the dissolved dispersion of the core substance to an aqueous medium containing a dispersion stabilizer, or vice versa.

Any method in which an aqueous medium containing a dispersion stabilizer is added to the dissolved dispersion can be used.

Mixing and stirring can be performed using a high-speed stirrer, an ultrasonic disperser, or the like. As the high-speed stirrer, a homomixer, homogenizer, colloid mill, homodisper, etc. can be used, and stirring is performed at several thousand revolutions or more.

The above-mentioned emulsification by mixing and stirring can be carried out at room temperature, but conditions such as heating, reduced pressure, or increased pressure can also be added if necessary.

In addition, when isocyanate is used as a hydrophobic polymerization compound, it is heated in the presence of a catalyst after emulsification.

It is preferable to carry out a reaction between isocyanate and water because it strengthens the capsule membrane.

Furthermore, when the viscosity of the core material is lowered using a low viscosity solvent in order to reduce the particle size by mixing and stirring, heating may be applied to remove the low viscosity solvent from the core material. It is valid.

As described above, a finely divided spherical core material is produced in the aqueous medium.

A hydrophilic polymerizable compound that undergoes a polymerization reaction with the hydrophobic polymerizable compound is added to the aqueous medium while continuing to stir gently to the extent that the core substance in the aqueous medium does not precipitate.

As a hydrophilic compound that undergoes such a polymerization reaction.

Ethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, phenylene diamine, 2-hydroxytrimethylene diamine.

Polyamines such as diethylenetriamine, triethylenetetramine, diethylaminoprobylamine, and tetraethylenepenkune, piperazine, and methylpiperazine.

Piperazines such as dimethylpiperazine, ethylene glycol, catechol, resorcinol, and hydroquinone.

Dihydroxymethylbenzene, dihydroxyethylbenzene, naphthalene diol, polythiol, etc. are used.

This polymerization reaction proceeds even at room temperature, but heating is also acceptable.

In addition, when using a polybasic acid as a hydrophobic polymerizable compound, it is preferable to add a small amount of an acid neutralizer such as sodium carbonate.

After the polymerization reaction is completed, the remaining hydrophilic polymerizable compound 1 dispersion stabilizer and the like can be washed off, if necessary. Examples of washing include washing with water, washing with warm water, etc., 3 to 4 times of decantation, or centrifugation.

The aqueous pigment dispersion obtained as described above can be used as a colorant for writing instrument inks, printing inks, paints, recording liquids, and the like. In other words, this aqueous pigment dispersion,
By adding it to resin varnishes, etc., inks, paints, and recording liquids without two-color separation can be obtained.

Furthermore, an aqueous resin dispersion,
It is also possible to mix an aqueous solution of a water-soluble resin or the like to obtain a composition similar to that of an ink or the like, or to form an ink or the like.

In other words, the particles encapsulated by the above-mentioned interfacial polymerization.

Fine resin particles that become hydrophobic upon drying are mixed with an aqueous resin dispersion or the like dispersed in water, and the resin in the resin dispersion is attached to the outer surface of the capsule to cover the capsule.

As such an aqueous resin dispersion, a dispersion produced by emulsion polymerization can be used as it is or after being condensed. It is also possible to use a dispersion obtained by soap-free emulsion polymerization. for example.

JP-A-58-127702.59-1503.59-1
Although it is obtained by the technique disclosed in Publication No. 99703, etc., it is preferable that the two dispersed particles have a spherical shape of about 0.01 to 1 μm and have a uniform particle size in order to obtain a uniform film.

For example, the resin in the resin dispersion includes styrene-methyl methacrylate copolymer, isobutyl methacrylate-methyl methacrylate copolymer, and the like.

Furthermore, it is also effective to use two or more types of aqueous resin dispersions for the purpose of multifacetedly changing the properties of the outer surface of fine resin particles having different properties.

In addition, those obtained by polymerizing the following vinyl monomers can also be used.

That is, examples of vinyl monomers include styrene monomers such as styrene, vinyltoluene, human-methylstyrene, and t-butylstyrene, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and 2-ethylhexyl. Acrylate, methyl methacrylate ethyl methacrylate.

Propyl methacrylate n-butyl methacrylate.

Acrylic acid or methacrylic acid alkyl esters such as isobutyl methacrylate and 2-ethylhexyl methacrylate, monobasic acids such as acrylic acid, methacrylic acid, and crotonic acid, dibasic acids such as fumaric acid, itaconic acid, and maleic acid, or their Ethylenically unsaturated male carboxylic acid monomers such as anhydrides, N-methylol acrylamide, N-methylol methacrylamide.

NW di(meth)acrylic monomers such as N-butoxymethylacrylamide and N-butoxymethylmethacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate,
Examples include hydroxyl group-containing monomers such as hydroxypropyl methacrylate, and epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate.

The resin dispersion liquid contains capsules 10 obtained by interfacial polymerization.
A solid content ratio of 0.3 to 10 parts by weight is used relative to 0 parts by weight. If it is less than 0.3 parts by weight, the surface of the capsule cannot be sufficiently covered, and if it is more than 10 parts by weight,
You can't get the desired effect by just adding it. Furthermore, there is a possibility that the capsules may aggregate with each other.

In addition, after mixing the capsule dispersion obtained by interfacial polymerization and the aqueous resin dispersion, the surroundings of the capsules can be mixed by adding a solvent, heating for sub-adjustment of pH, or charging two particles by cooling and coagulation. An operation may also be used in which a resin in an aqueous resin dispersion is attached to the resin.

Two embodiments of the present invention will be described below. In the examples, 5 parts indicates parts by weight.

Example 1 (1) Preparation of oil-based pigment dispersion Taipur R-900 (inorganic pigment manufactured by DuPont Japan) 10 parts Risunome Blue SM (organic pigment manufactured by Toyo Ink Manufacturing Co., Ltd.)
10 parts Tamanol 350 (rosin-modified phenolic resin manufactured by Arayo Kagaku Kogyo ■)
10 parts Swazol 1000 (high boiling point organic solvent manufactured by Maruzen Sekiyu ■) 1
0 parts The mixture of the above formulation was dispersed in a Miki roll mill to obtain a soft oily pigment dispersion.

(2) Preparation of diluted oil pigment dispersion The above oil pigment dispersion 10 parts Swasol 1000 50 parts Millionate MR-200 (Japan Polyurethane (horizontally split isocyanate) 10 parts were mixed and a low viscosity oil pigment dispersion diluted solution was prepared. Obtained.

(3) Emulsified Emulgen 913 (nonionic activator manufactured by Kao ■) 15 parts water 3
00 parts of the aqueous solution was stirred at 400 rpm with a high-speed mixer (desktop high-speed mixer made by Tokushu Kika Kogyo Aren), and 70 parts of the diluted oil-based pigment dispersion solution was added dropwise over 10 minutes.After 9 drops had been added, the mixture was stirred for 10 minutes. Stirring was continued to effect emulsification.

(4) After encapsulation and emulsification, 40 parts of a 10% diethylene triamine aqueous solution was added at the same rotational speed, and stirring was continued for 1 hour to cause an interfacial polymerization reaction to obtain a microcapsule aqueous pigment dispersion with an oil pigment dispersion as a core material. Ta.

This aqueous pigment dispersion has a pH of 9.7 and a tube gauge of 10μ.
m or less, microscopically observed average particle size 1.5 μm, same shape 6.5
%, and the viscosity was 13 cps.

Example 2 (1) Creation of oil-based pigment dispersion Taipur R-101 (inorganic pigment manufactured by DuPont Japan)
10 parts Brilliant Carmine 6B (organic pigment manufactured by Toyo Ink Seisakusho)
10 parts ester gum AAC, (rosin ester manufactured by Arayo Kagaku Kogyo ■)
10 parts polybutene oil (LV-10 manufactured by Nippon Oil Co., Ltd.)
) 10 parts xylene 5 parts An oil pigment dispersion was obtained in the same manner as in Example 1.

(2) Preparation of oil-based pigment dispersion diluted liquid Oil-based pigment dispersion 10 parts Xylene 50 parts Coronate L
(Isocyanate manufactured by Nippon Polyurethane)
10 parts were mixed to obtain a low-viscosity oil-based pigment dispersion diluted liquid.

(3) Emulsified Demol N (anion activator manufactured by Kao ■) 20 parts water
300
An aqueous solution was prepared and emulsified in the same manner as in Example 1.

(4) After encapsulation and emulsification, 40 parts of methylene diamine aqueous solution was added to the 10% rotation speed, and the same procedure as in Example 1 was carried out to obtain a microcapsule aqueous pigment dispersion with an oil-based pigment dispersion as the core material. Ta.

This aqueous pigment dispersion has a pH of 9.3 and a tube gauge of 10μ.
m or less, and the viscosity was 20 cps.

Example 3 (1) Creation of oil-based pigment dispersion Taipur R-101 10 parts Lisunome Yellow G Toner (organic pigment manufactured by Toyo Ink Manufacturing a@) 10 parts Vylon 300 (Toyobo (polyester resin manufactured by Ikiku) 10 parts Toluene 20 5 parts ethyl acetate The mixture of the above formulation was dispersed using an attritor to obtain a soft oily pigment dispersion.

(2) Preparation of diluted oil pigment dispersion liquid Above oil pigment dispersion 15 parts toluene 30 parts ethyl acetate
5th part subrak 1160
(Isocyanate manufactured by Nippon Polyurethane)
10 parts were mixed to obtain a low-viscosity oil-based pigment dispersion diluted liquid.

(3) Emulsified hydroxylethyl cellulose BG-15 (Fuji Chemical ■g) 0.5 parts Emulgen A-60 (nonionic activator manufactured by Kao ■) 5 parts water 3
00 parts of an aqueous solution was prepared and emulsified in the same manner as in Example 1.

(4) Encapsulation A microcapsule aqueous pigment dispersion having an oil-based pigment dispersion as a core material was obtained in the same manner as in Example 1 using a 10% aqueous triethylenetetramine solution.

This aqueous pigment dispersion has a pH of 9.5 and a tube gauge of 10μ.
m or less, microscopic observation, average particle size 1.3 μm, viscosity 12c
It was ps.

Example 4 (1) Preparation of oil-based pigment dispersion Romuelo NEO5GS (inorganic pigment manufactured by Nippon Inorganic Chemical ■) 15 parts Risunome Blue SM 5 parts Vetrozine 12
0 (manufactured by Mitsui Petrochemical Co., Ltd.) 7 parts Toluene 20 parts In the same manner as in Example 3, an oil pigment dispersion was obtained.

(2) Preparation of diluted oil-based pigment dispersion 10 parts of the above oil-based pigment dispersion, 50 parts of toluene, and 10 parts of Desmodur R (Isocyanate manufactured by Bayer) were mixed to obtain a diluted oil-based pigment dispersion with low viscosity.

(3) Emulsified PVA-205 (polyvinyl alcohol manufactured by Kuraray ■)
5 parts water
300 parts of an aqueous solution was prepared and emulsified in the same manner as in Example 1.

(4) Encapsulation A microcapsule aqueous pigment dispersion with an oil-based pigment dispersion as the core material was obtained in the same manner as in Example 1 using 40 parts of a 10% piperazine aqueous solution.

This aqueous pigment dispersion has a pH of 9.2 and a tube gauge of 10μ.
m or less, microscopic observation, average particle size 3.7 μm, viscosity 16c
It was ps.

Example 5 (1) Preparation of oil-based pigment dispersion 10 parts Taipur R-900 10 parts Rimxo-NEO5GS' 10 parts Lithium blue SM 5 parts Evaflex 40 (ethylene vinyl acetate resin manufactured by Mitsui Polychemicals ■) 5 parts dioctyl phthalate 10 parts xylene
An oil pigment dispersion was obtained using 10 parts in the same manner as in Example 1.

(2) Preparation of diluted oil-based pigment dispersion 10 parts of the above oil-based pigment dispersion 50 parts of xylene 10 parts of Desmodur R were mixed to obtain a diluted oil-based pigment dispersion with low viscosity.

(3) Emulsification Emulsification was performed in the same manner as in Example 1.

(4) Encapsulation A microcapsule aqueous pigment dispersion with an oil-based pigment dispersion as the core material was obtained in the same manner as in Example 1, except that a 15% resorcinol aqueous solution was used and heated to 50°C.

This aqueous pigment dispersion has a pH of 6.3 and a tube gauge of 10μ.
m or less, microscopic observation, average particle size 5.6 μm, viscosity 35c
It was ps.

Example 6 (1) Creation of oil-based pigment dispersion Mapico Red R516L (inorganic pigment manufactured by Titan Kogyo A1)
Part 2 Thai Pure R
90010 parts Silane 420 (Columbia Carbon Inorganic Pigment 10
Part Paraloid B-66 (Methacrylic acid resin manufactured by Rohm & Haas) 5 parts Toluene
20 parts were dispersed in a whole mill to obtain an oil pigment dispersion.

(2) Preparation of diluted oil pigment dispersion The above oil pigment dispersion 10 parts Toluene 40 parts Methyl ethyl ketone 10 parts Millionate MT
(Isocyanate made by Nippon Polyurethane)
10 parts were mixed to obtain a low-viscosity oil-based pigment dispersion diluted liquid.

(3) Emulsification Emulsification was performed in the same manner as in Example 1.

(4) Encapsulation In the same manner as in Example 1, a microcapsule aqueous pigment dispersion containing an oil-based pigment dispersion as a core material was obtained.

This aqueous pigment dispersion has a pH of 9.2 and a tube gauge of 10μ.
m or less, microscopic observation, average particle size 1.9 μm, viscosity 18c
It was ps.

Example 7 (1) Preparation of oil-based pigment dispersion Taipur R900 10 parts Kurimuello NEO5GS 10 parts Brilliant Carmine 6B 2 parts Sumolite P (Seiko Kagaku Seiko Cyclized Rubber) 5 parts Toluene
25 parts were dispersed in a whole mill to obtain an oil pigment dispersion.

(2) Preparation of diluted oil-based pigment dispersion 10 parts of the above oil-based pigment dispersion, 50 parts of toluene, and 10 parts of Millionate MT were mixed to obtain a diluted oil-based pigment dispersion with low viscosity.

(3) Emulsification Emulsification was performed in the same manner as in Example 1.

(4) Encapsulation In the same manner as in Example 1, a microcapsule aqueous pigment dispersion containing an oil-based pigment dispersion as a core material was obtained.

This aqueous pigment dispersion had a pH of 9°O and a tube gauge of 10μ.
m or less, microscopic observation, average particle size 3.0 μm, viscosity 23c
It was ps.

Comparative Example 1 (1) Preparation of oil-based pigment dispersion A soft oil-based pigment dispersion was obtained in the same manner as in Example 1 (1) Preparation of oil-based pigment dispersion.

(2) Preparation of diluted oil-based pigment dispersion 10 parts of oil-based pigment dispersion and 50 parts of Swasol 1000 were mixed to obtain a diluted oil-based pigment dispersion with low viscosity.

(3) Emulsification The same procedure as (3) Emulsification in Example 1 was carried out to obtain a low-viscosity emulsion of an oil-based pigment dispersion.

This emulsion has a pH of 7.0 and a tube gauge of 10μ or less.

Microscopic observation revealed that the average particle size was 1.7 μm and the viscosity was 21 cps.

In Comparative Example 1, the treatment was stopped before the encapsulation treatment was performed, and the effect of encapsulation can be compared.

Comparative Example 2 (1) Preparation of an oil-based pigment dispersion A soft oil-based pigment dispersion was obtained in the same manner as in Example 2 (1) Preparation of an oil-based pigment dispersion.

(2) Preparation of diluted oil-based pigment dispersion 10 parts of oil-based pigment dispersion and 50 parts of xylene were mixed to obtain a diluted oil-based pigment dispersion with low viscosity.

(3) Emulsification The same procedure as (3) Emulsification in Example 2 was carried out to obtain a low-viscosity emulsion of an oil-based pigment dispersion.

This emulsion has a pH of 7.1 and a tube gauge of 10 μm or less.

Microscopic observation revealed that the average particle size was 2.0 μm and the viscosity was 37 cps.

Comparative Example 3 10 parts of Taipur R900 10 parts of Risunome Blue SM Johncryl 678.30% ammonia aqueous solution (Johnson-
Styrene acrylic resin) 50 parts water
30 parts of the mixture of the above formulation was dispersed in a ball mill, pH 8°3, tube gauge 30.
An aqueous pigment dispersion having an average particle size of 0.13 μm and a viscosity of 470 cps was obtained.

Comparative Example 4 Dispersion of Comparative Example 3 20 parts water
80 parts of the mixture was prepared, the viscosity was 15 cps, the tube gauge was 30 μm,
An aqueous pigment dispersion having a pH of 7.7 and an average particle size of 0.13 μm was obtained.

By comparing this dispersion with the dispersion of Example 1, the encapsulation effect can be confirmed.

Comparative Example 5 Typure R10 10 parts Brilliant Carmine 6B 10 parts Emulgen A-60 5 parts Demol N
1 part water
74 parts The mixture of the above formulation was dispersed in a sand mill, pH 7°8, tube gauge 10 μm.
Below, the average particle size is 0.15 μm.

An aqueous pigment dispersion with a viscosity of 37 cps was obtained.

Comparative Example 6 Chrome Yellow NEO5GS 15 parts Risunome Blue SM 5 parts Marquid N
o32. 30% ammonia aqueous solution (rosin-modified maleic acid resin manufactured by Arayo Kagaku Kogyo) 30 parts casein 15% ammonia aqueous solution 30 parts water
20 parts of the mixture of the above formulation was dispersed with an attritor, pH 8,
8. Tube gauge 10 μm, average particle size 0.20 μm.

An aqueous pigment dispersion with a viscosity of 830 CpS was obtained.

Comparative Example 7 Thai Pure R900 10 parts Kurimu Elo NEO5GS L0 part Risunome Blue SM S part Casein 15
% ammonia aqueous solution 30 parts Styrite CM15 ammonia aqueous solution (styrene maleic acid resin manufactured by Daido Kogyo) 10 parts water
39
The mixture of the above formulation was dispersed in a ball mill to obtain an aqueous pigment dispersion having a pH of 8.5, a tube gauge of 30 μm, an average particle size of 0.32 μm, and a viscosity of 2150 cps.

Comparative Example 8 Mapico Red R516L 2 parts Typure R900 10 parts Silane 420 10 parts Shincryl 74J (acrylic resin manufactured by Johnson IAI) 40 parts Water 4
0 parts The mixture of the above formulation was dispersed in a sand mill, and the pH was adjusted to 8.
゜2, lump gauge 1 (lcrm, average particle size 0.28 μm
, an aqueous pigment dispersion with a viscosity of 47 cps was obtained.

*1. Measurement using BL type viscometer (manufactured by Tokyo Keiki) *2. Observation of assembled particles using a tube gauge The assembled particles of the dispersion were observed using a method according to JIS K-5400.

*3. Drop the dispersion onto a glass plate and cover with a cover glass. The average particle diameter was determined by examining the particle diameter in 5 fields of view with 20 particles per 1 field of view using an optical microscope with a 500 binder.

*4. The average particle diameter of the pigment particles of the dispersion was determined using a centrifugal sedimentation type particle size distribution analyzer (manufactured by Shimadzu Corporation).

*5. A sample was placed in a 300 mm height test tube with a stopper to a height of 290 mm and stored at a constant temperature of 50° C. in a test tube room.

After 30 days, separation, precipitation, and color separation of the dispersion were observed. After observation, the material was returned to a dispersed state by strong shaking and the viscosity was measured.

Claims (1)

[Claims] The core substance of an oil-based pigment dispersion containing one or more pigments, a resin, and an organic solvent for dissolving the resin is encapsulated in a shell formed by interfacial polymerization, and if necessary, An aqueous pigment dispersion characterized by being formed by mixing an aqueous resin dispersion or a water-soluble resin aqueous solution. 2. The aqueous pigment dispersion according to claim 1, wherein the capsules have a particle size of 0.2 to 10 μm.