JPH05247371A - Aqueous dispersion of pigment - Google Patents

Abstract

PURPOSE:To provide an aqueous dispersion of pigment having low viscosity, high pigment content and excellent pigment dispersibility and capable of giving a written mark or a coating film having excellent abrasion resistance. CONSTITUTION:The objective aqueous pigment dispersion is composed of a water-soluble resin, a pigment and water. The water-soluble resin is composed of a tetrabasic acid and a diol consisting of an ethylene oxide adduct of bisphenol A and/or a propylene oxide adduct of bisphenol A and/or a polycondensation product of the adduct with phthalic acid.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous pigment dispersion used in the coloring material industry. More specifically, it relates to an aqueous pigment dispersion liquid which is useful for producing an aqueous flexographic ink, an aqueous coating material, an aqueous ink for a writing instrument and the like using a pigment.

[0002]

2. Description of the Related Art Conventionally, in the coloring material industry, various aqueous resins are used as dispersants to disperse pigments, and the pigments are commercially available as colorants as they are or mixed with various aqueous resin solutions to prepare aqueous paints and inks. Used in manufacturing. Conventionally, as a water-soluble resin as these dispersants, an acrylic resin having a carboxyl group introduced, a styrene-acrylic resin, a styrene-maleic acid resin, a rosin-modified maleic acid resin and the like have been used.

[0003]

Regarding the inks and paints, the water-based type is preferable in various respects, but when drying these inks and paints, the latent heat of vaporization of water is larger than the latent heat of vaporization of the solvent. With non-volatile matter, there is a problem that water-based paints and water-based inks dry more slowly than solvent-based paints. Therefore, it is desirable that the water-based paint or water-based ink has a higher concentration (that is, less water content) than the solvent-based paint or ink, and therefore various measures have been taken. In order to obtain a high-concentration aqueous paint, it is desirable to use a water-dispersible resin. However, in order to prepare a paint using a water-dispersible resin, the pigment must first be sufficiently dispersed. The pigment is usually dispersed in a water-soluble resin,
In order to increase the pigment content as much as possible, the degree of polymerization of the water-soluble resin must be lowered. If the degree of polymerization of the water-soluble resin is lowered, the physical properties of the coating film deteriorate. This also applies to the water-based flexo ink. The same applies to water-based inks for writing utensils, and when it is attempted to increase the pigment concentration, the abrasion resistance of writings deteriorates. Therefore, an object of the present invention is to provide an aqueous pigment dispersion liquid which has a low viscosity and a high pigment content, has good pigment dispersibility, and provides a writing and a coating film having excellent abrasion resistance.

[0004]

The above objects can be achieved by the following inventions. That is, the present invention provides an aqueous pigment dispersion liquid comprising a water-soluble resin, a pigment and water, wherein the water-soluble resin is a water-soluble resin comprising a tetrabasic acid and a specific diol, and the specific diol is bisphenol A. Is an ethylene oxide additive and / or a propylene oxide additive and / or a polycondensation product of the additive and phthalic acid.

[0005]

A water-soluble resin comprising a tetrabasic acid and a specific diol, wherein the specific diol is an ethylene oxide additive and / or a propylene oxide additive of bisphenol A and / or a condensation of the additive with phthalic acid. By using a water-soluble resin, which is a polymer, as a dispersant for pigments, an aqueous pigment dispersion liquid that has a low viscosity, high pigment content, good pigment dispersibility, and provides a writing or coating film with excellent abrasion resistance can be obtained. Can be provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. The dispersant used in the present invention is a water-soluble resin composed of a tetrabasic acid and a specific diol, wherein the specific diol is bisphenol A with an ethylene oxide additive and / or a propylene oxide additive and / or the additive. It is characterized by being a polycondensation product of phthalic acid and phthalic acid. The tetrabasic acid constituting the dispersant, pyromellitic acid, naphthalene tetracarboxylic acid, biphenyl tetracarboxylic acid, benzophenone tetracarboxylic acid, and the like, further derivatives thereof, for example,
Acid anhydrides, acid halogenites, lower alcohol esters and the like can be used. Pyromellitic acid is particularly preferable as the tetrabasic acid. Since the above-mentioned tetrabasic acid is used for polycondensation and for making the resulting polyester resin water-soluble, it is necessary not to cause gelation by polycondensation and to leave a carboxyl group for water-solubilization. Is.

A preferred method for synthesizing the water-soluble resin used as the dispersant in the present invention is a method in which pyromellitic dianhydride is used for ring-opening addition, and it is desirable that the reaction is carried out under the condition that dehydration reaction does not occur. The diol is the basis of the dispersant used in the present invention. The hydrophilicity (acid value), hardness, strength and pigment dispersibility of the water-soluble resin according to the present invention are determined by the selection of the diol. The diols which meet the object of the present invention are ethylene oxide and / or propylene oxide adducts of bisphenol A, and / or polycondensation products of the adducts with phthalic acid. Further, regarding phthalic acid, orthophthalic acid, isophthalic acid and terephthalic acid are mentioned, and terephthalic acid is particularly desirable. The use ratio of pyromellitic dianhydride and the above diol is determined by the molecular weight of the water-soluble resin obtained. The molecular weight that can be used is approximately 1,500 to 8,000, preferably 2,000 to 7,000. If the molecular weight is less than 1,500, the abrasion resistance of the writing material or coating film is weak, and if the molecular weight exceeds 8,000, the viscosity of the dispersion becomes too high, which is not suitable for the purpose of the present invention.

The selection of the diol is determined by the hydrophilicity (acid value) of the water-soluble resin obtained. When the dispersant of the present invention is used in an aqueous flexo ink, the acid value of the resin is preferably high. For example, a polycondensation product (acid value 180) of 5 moles of pyromellitic dianhydride and 6 moles of bisphenol A with 2 moles of propylene oxide is suitable. A slightly higher acid value is preferable for water-based inks for writing instruments and water-based jet printing inks. For example, 4 mol of pyromellitic dianhydride, 2 mol of a polycondensation product of 2 mol of bisphenol A with ethylene oxide and 1 mol of terephthalic acid, and 3 mol of polycondensation of 2 mol of bisphenol A with 2 mol of ethylene oxide. Thing (acid value 13
2) is suitable. Further, those having a slightly low acid value are suitable for dispersing pigments for water-based paints. For example, a polycondensation product (acid value 87) of 3 mol of pyromellitic dianhydride, 2 mol of propylene oxide of 2 mol of bisphenol A, and 4 mol of a polycondensation product of 1 mol of terephthalic acid is suitable.

The acid value can also be changed by post-treatment such as esterifying the carboxylic acid of the resulting water-soluble resin with a monoalcohol or acylating with an amine. As the conditions for polycondensation of the acid component and the diol component, it is desirable to flow nitrogen gas at a temperature of 140 to 170 ° C. for 4 to 10 hours. A solvent can be used if necessary. The solvent is preferably water-soluble and has no active hydrogen. The water-soluble resin used as a dispersant in the present invention can be dissolved in water as an ammonium salt, an amine salt, or an alkali metal salt. After completion of the polycondensation reaction, the product may be taken out as it is, cooled and pulverized, and then dissolved in water and a neutralizing agent. Alternatively, after the polycondensation reaction is completed, it is neutralized in the same reaction vessel and water is added thereto. It may be taken out as an aqueous solution. When it is taken out as an aqueous solution, the neutralizing agent and water are added after cooling to 100 ° C. or lower, but when cooled to 100 ° C. or lower, the viscosity of the liquid increases, so it is advisable to add a water-soluble solvent. The solvent at this time may have active hydrogen.

In the above polycondensation reaction, tribasic acids such as trimellitic acid and dibasic acids such as phthalic acid and other alcohols may be added within the range not impairing the object of the present invention. The water-soluble resin thus obtained has good coating strength (rubbing resistance) despite its low molecular weight, and also has excellent pigment dispersibility. When the pigment is dispersed using the water-soluble resin, a pigment dispersion having a high pigment content, low viscosity and good dispersion can be obtained. By using this aqueous pigment dispersion, high-concentration aqueous flexo ink,
It is possible to obtain water-based paints, water-based inks for writing instruments with high concentration and high abrasion resistance, jet printing inks, and the like. For dispersing the pigment using the water-soluble resin as a dispersant, the conventional method using a carboxy type water-soluble resin can be used as it is.

When the water-soluble resin in the present invention is used to disperse the pigment, any known pigment such as organic pigments and inorganic pigments can be used. Examples of organic pigments include phthalocyanine-based, azo-based, anthraquinone-based, perinone-perylene-based, indigo-thioindigo-based, isoindolinone-based, azomethine-based, azomethineazo-based, dioxazine-based, quinacridone-based, aniline black-based, triphenyl Examples thereof include methane type and carbon black type, and examples of the inorganic pigment include titanium oxide type, iron oxide type, iron hydroxide type, chromium oxide type, spinel type calcined pigment, lead chromate type and the like. When the pigment is dispersed using the water-soluble resin, a water-soluble solvent can be used if necessary. For example, carbon number 1
Alcohols of 3 to 3, ethylene glycol monoethers of alcohols of 1 to 4 carbons, diethylene glycol monoether, propylene glycol monoether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol, diethylene glycol, propylene glycol and the like can be used.

As for the disperser, there is no problem except that it is water-based, and a disperser using beads of glass or zircon, or a ceramic ball mill can be used. Ball mills made of non-rust steel can also be used with care. or,
The water-soluble resin and the pigment taken out in solid form are kneadered,
It is also possible to knead with a Banbury mixer or a mixing roll to form color chips, which can be dissolved in water and a neutralizing agent.

EXAMPLES Next, the present invention will be described more specifically with reference to examples. In the text, "parts" or "%" means "parts by weight" or "% by weight" unless otherwise specified.

Example 1 1209.6 parts of bisphenol A supplemented with 2 mol of propylene oxide, 349.2 parts of dimethyl terephthalate and 0.5 parts of tetra-n-butoxytitanium were placed in a reaction vessel at 210 ° C. in a nitrogen stream. Stir for 10 hours. 15
After cooling to 0 ° C., 294.3 parts of pyromellitic dianhydride and 434.7 parts of diethylene glycol dimethyl ether were added, and the temperature was once adjusted to 170 ° C. in a nitrogen stream, and then at 6 ° C. at 150 ° C.
Stir for hours. Further, 434.3 parts of ethylene glycol monobutyl ether is added and stirred. The reaction mixture is 80
After cooling to 0 ° C., a mixed solution of 163.9 parts of 28% ammonia water and 1,574.1 parts of water is added and well stirred. It is cooled and taken out to obtain a water-soluble resin liquid-1. 100 parts of the above water-soluble resin liquid-1 is dissolved in 431 parts of water, and 9 parts of 28% ammonia water is added. To this solution, 360 parts of solvent-stabilized copper phthalocyanine blue is added, stirred and dispersed by a horizontal bead mill to obtain Pigment Dispersion Liquid-1 of the invention. To 100 parts of a white acrylic emulsion paint (for exterior: glossy), 5 parts of the above pigment dispersion liquid-1 was added,
When the paint obtained by stirring was applied to the slate plate by brushing, a beautiful blue surface was obtained without any deterioration in gloss or color separation.

Example 2 360 parts of an aqueous alkyd resin (resin content 50%, butyl cellosolve 20%, water 30%; water diluted dispersion type) 360 parts, rutile type titanium dioxide pigment 250 parts, water 330 parts and water-soluble melamine crosslinking agent 60 parts Is dispersed using a sand mill to give White Paint-2. 650 parts of valve handle to 17 of water-soluble resin liquid-1
Dispersed in 0 part and 180 parts of water, the pigment dispersion liquid of the present invention-2
And To 370 parts of the white paint-2, 30 parts of the pigment dispersion-2 is added and stirred to obtain a colored paint-2.
Apply the above colored paint-2 to a tin plate with an applicator.
After coating to a thickness of 6 μm / wet and air-drying, 130 ℃ 3
The coated plate was baked for 0 minutes. This coated plate had a beautiful light brown color and the surface condition of the coating film was good.

Example 3 150 parts of water-soluble resin liquid-1 was dissolved in 520 parts of water, and 2
30 parts of 8% ammonia water and 300 parts of carbon black are added and stirred. This is dispersed by a horizontal bead mill to obtain a pigment dispersion liquid-2 of the invention. Acrylic resin emulsion for paint (MFT 15 ° C.) 90 parts, 5 parts of the above pigment dispersion-2, thickener (nonionic activator type) 0.0
2 parts, 4.98 parts of water and 3 parts of texanol (film forming aid) were mixed and stirred to obtain a paint. The paint showed no deterioration in gloss in a storage stability test at 50 ° C. for 1 month. In addition, the paint applied to a steel plate (32 μm / dry) had good gloss and did not swell in the water resistance test for one week. The paint is most suitable as a black paint for chassis.

Example 4 700 parts of pyromellitic dianhydride, 1,232 parts of bisphenol A with 2 mol of propylene oxide and 700 parts of diethylene glycol dimethyl ether were charged into a reaction vessel, and the temperature was raised to 165 ° C. in a nitrogen stream.
Heat and stir at 6 ° C for 6 hours. Cool to 90 ° C and water 1,8
A mixed liquid of 13 parts and 385 parts of 28% ammonia water is added, stirred, cooled, and taken out to obtain a water-soluble resin liquid-4.
To 400 parts of water, 70 parts of the above water-soluble resin liquid-4 and 12 parts of 28% ammonia water are added and stirred, 300 parts of permanent carmine 2B is added and stirred, and dispersed by a horizontal bead mill, and the water-soluble resin liquid- Dispersion liquid 4 was prepared by adding 70 parts of No. 4 and 150 parts of water and stirring. Aqueous flexo prepared by mixing and stirring 48.8 parts of an acrylic / styrene emulsion resin (resin content 47%) using water-soluble acrylic resin as a protective colloid, 50 parts of the above Dispersion-4 and 1.2 parts of a low molecular weight polyethylene emulsion. Ink-4. Printing on corrugated liner paper with the water-based flexo ink-4 gave a beautiful printed matter. The printed matter was subjected to a Gakushin-type friction tester using liner paper as a test paper at a load of 200 g for 10
A rubbing test was conducted, but color fading was slight.

Example 5 Bisphenol A Ethylene Oxide 2 mol Additive 6
16 parts dimethyl terephthalate 194 parts tetra-n-
0.4 parts of butoxytitanium is placed in a reaction vessel, and the reaction is carried out by stirring in a nitrogen stream at 170 ° C. for 10 hours. The above reaction mixture was cooled to 150 ° C., and 462 parts of ethylene oxide 2 mol addition product of bisphenol A, 428 parts of pyromellitic dianhydride and diethylene glycol dimethyl ether 43 were added.
5.5 parts were added and the mixture was once heated to 165 ° C. and then stirred at 150 ° C. for 6 hours in a nitrogen stream. Cool to 85 ° C,
A mixed liquid of 242.8 parts of 28% ammonia water and 1,934.7 parts of water is added, well stirred, and taken out to obtain a water-soluble resin liquid-5. Water 308 parts, ethylene glycol 80
Parts, 8 parts of ammonia water and 80 parts of water-soluble resin liquid-5 are mixed well, 320 parts of copper phthalocyanine blue (solvent unstable type) is added thereto, stirred and dispersed by a horizontal bead mill. 2,048 parts of water and 160 of water-soluble resin liquid-4
Parts, 176 parts of ethylene glycol, and 16 parts of 28% ammonia water are added, stirred, and subjected to ultracentrifugation to remove coarse particles to obtain dispersion-5. The dispersion liquid-5 has a viscosity of 3.
It was as low as 5 cps and had a pH of 9.1. As a result of filling this in a ballpoint pen and writing on Kent paper, it is dark blue,
Writing fast didn't cause blurring. Further, the written portion was subjected to a friction test with a Gakushin type friction tester, and as a result, there was little white paper contamination and good results were obtained.

[0018]

[Effect] As described above, the aqueous pigment dispersion of the present invention has a low viscosity and a high solid content, is resistant to friction, and is suitable as a coloring agent for aqueous flexographic inks, aqueous inks for writing instruments, aqueous inks for jet printing or aqueous paints. There is.

Claims (4)

[Claims] 1. An aqueous pigment dispersion liquid comprising a water-soluble resin, a pigment and water, wherein the water-soluble resin is a water-soluble resin comprising a tetrabasic acid and a specific diol, and the specific diol is bisphenol A. An aqueous pigment dispersion characterized by being an ethylene oxide additive and / or a propylene oxide additive and / or a polycondensation product of the additive and phthalic acid. 2. The aqueous pigment dispersion according to claim 1, wherein the tetrabasic acid is pyromellitic acid. 3. The water-soluble resin has a molecular weight of 1,500 to 8,
The aqueous pigment dispersion liquid according to claim 1, which is 000. 4. The aqueous pigment dispersion according to claim 1, wherein the water-soluble resin has an acid value of 40 to 200.