JPS5952169B2 - Method for producing pigment dispersion composition for thermosetting coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a pigment dispersion composition for thermosetting coatings that can be particularly advantageously used in the production of slurry coatings or powder coatings, and more specifically, a method for producing a pigment dispersion composition for thermosetting coatings, and more particularly, a method for producing a pigment dispersion composition for thermosetting coatings that can be advantageously used in the production of slurry coatings or powder coatings. This invention relates to a method that uses a specific suspension stabilizer to eliminate the adverse effects caused by conventional suspension stabilizers and forms a coating film with excellent gloss, smoothness, etc.

Resins produced by suspension polymerization are susceptible to the suspension stabilizer used during the polymerization.

This is because the suspension stabilizer mixes into the resin and brings with it the drawbacks of the suspension stabilizer. For example, if the compatibility between the suspension stabilizer and the resin is poor, the gloss of the coating composition will be reduced. If the suspension stabilizer has a high melting point, it decomposes and becomes colored when heated, resulting in a decrease in thermal fluidity and thermal stability. Furthermore, since the suspension stabilizer itself is water-soluble, water resistance, corrosion resistance, weather resistance, etc. are impaired. Under such circumstances, great efforts have been made and many studies have been made to efficiently remove suspension stabilizers from systems containing them, but no satisfactory results have been obtained. In particular, the above-mentioned defects become a big problem in thermosetting filter slurry paints and powder paints in which this type of resin is used as is for painting without being crushed or kneaded. For example, when methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, etc. are used as suspension stabilizers, such suspension stabilizers cannot be easily removed by simple washing, and the resulting resin particles are used as they are in slurry paints or powder paints. In this case, the gloss, smoothness, etc. of the formed coating film are extremely poor.
An object of the present invention is to provide a method for producing a pigment dispersion composition for thermosetting coatings that can be effectively used as a slurry coating or a powder coating.

The present inventors have carried out intensive research to achieve this objective, and have found that high molecular weight polyethylene glycol has a function as a suspension stabilizer in an aqueous medium, and has a softening point of about 65 to 65. Focusing on the fact that it decomposes into low-boiling-point, low-molecular-weight compounds without coloring when heated at a low temperature of 67°C, and moreover at about 150°C, suspension polymerization was carried out using such polyethylene glycol as a suspension stabilizer, and after the polymerization. The resin obtained by simple washing and separation of the reaction system is not adversely affected by suspension stabilizers, and the gloss, thermal fluidity, and thermal stability, which are important properties for slurry paints and powder paints, are inhibited. It has been found that a coating film with excellent gloss, smoothness, etc. without coloring can be obtained.

The present invention was completed based on the above-mentioned findings, and the gist thereof is that a pigment A, a polymerizable monomer having 1 hydroxyl group, and a polymerizable monomer having 2 glycidyl groups is selected from the group. A liquid pigment dispersion composition containing a polymerizable monomer mixture B) containing 5 to 40% by weight of at least one alkyd resin C) and a crosslinking agent D is suspended and polymerized in an aqueous medium to disperse pigments for thermosetting coatings. In the method for producing a composition, as a suspension stabilizer during the polymerization, a compound having a molecular weight of 100,000 to 3
The present invention relates to a method for producing a pigment dispersion composition for thermosetting coatings, characterized in that polyethylene glycol of 0.00000 is used.

The pigment A used in the present invention may be one commonly used in commercially available paints, inks, plastics, etc. For example, inorganic pigments mainly composed of simple elements such as carpon plaque, aluminum powder, mica powder, etc. things, Zn, Pb, Ti, Sb, Cd, Fe, As,
Oxides, sulfates, sulfides, chromates, silicates, hydroxides, carbonates, etc. of Mg, Al, Ba, Ca, Si, CO, Cr, etc. Organic pigments include natural dye pigments, nitroso pigments, etc. Pigments, nitro pigments, azo pigments, phthalocyanine pigments, basic dye pigments, acid dye pigments, vat dye pigments, mordant dye pigments, as well as quinacridone red, quinacridone violet, berylene red, perylene. Examples include scarlet, isoindolinone pigment, dioxazine violet, aniline plaque, and organic fluorescent pigment.

The amount of such pigment used is usually about 1% in the liquid pigment dispersion composition.
It is preferable to select the amount in the range of 70% by weight, and especially if it exceeds about 70% by weight, the liquid pigment dispersion composition may become thickened and difficult to handle. In addition, when selecting these pigments, consideration should be given to avoid undesirable side reactions during the polymerization reaction with other components such as the polymerizable monomer mixture B) resin C) crosslinking agent D, etc. This is desirable. As the polymerizable monomer mixture B used in the present invention, at least one kind selected from the group of polymerizable monomers (1 to 2) shown below may be used alone or in combination.
Examples include those containing 0% by weight, preferably 10 to 30% by weight.

If the blending ratio of the polymerizable monomers (1 to 2) is less than 5% by weight, the crosslinking density will be low and the physical properties of the cured coating film (e.g. mechanical strength, solvent resistance, chemical resistance, etc.) will deteriorate. Moreover, if it exceeds 40% by weight, the crosslinking density becomes high, the cured coating becomes brittle, and unreacted functional groups tend to remain, which may adversely affect water resistance, weather resistance, etc. Become. Polymerizable monomers having 1 hydroxyl group (e.g. 2-
Hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, polypropylene glycol monomethacrylate, glycol monomethacrylate and 3-chloro-2-hydroxypropyl methacrylate When such monomers are used, polymerizable monomers It is desirable that the proportion in the body mixture is 30% by weight or less,
Further, as the corresponding crosslinking agent D, aminoplast resins, protox isocyanate compounds, etc. are suitable.

Polymerizable monomers having 2 glycidyl groups (eg glycidyl acrylate, methylglycidyl acrylate, glycidyl methacrylate and methylglycidyl methacrylate).

Suitable crosslinking agents D for such monomers include organic compounds having two or more carboxyl groups, polyamines, and the like. As the polymerizable monomer that may be used in combination with monomers 1 and 2 above, ordinary ones can be used, and examples thereof include the following.

5 Polymerizable monomers represented by the general formula [wherein R3 represents a hydrogen atom or a methyl group, and R4 represents a C1 to C18 alkyl group] (e.g. enal acrylate, n-butyl acrylate, isobutyl acrylate, t- butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate and lauryl methacrylate).

When such monomers are used, they are preferably used in a proportion of about 30 to 95% by weight in the polymerizable monomer mixture. Contribute to providing. 5-styrene and its derivatives (e.g. α-
methylstyrene, vinyltoluene and p-t-butylstyrene).

When such monomers are used, it is desirable that the proportion is about 50% by weight or less in the polymerizable monomer mixture, and these monomers are highly copolymerizable with other polymerizable monomers and are Gives excellent gloss. However, the above usage rate is about 50
If the amount exceeds % by weight, the weather resistance of the cured coating film tends to decrease. The amount of the polymerizable monomer mixture having such a monomer composition is preferably selected within the range of about 20 to 90% by weight of the liquid pigment dispersion composition.

As the resin C used in the present invention, alkyd resins (eg, polyester resins and oil- or fatty acid-modified alkyd resins) are representative. In the case of this resin, graft active sites (for example, active hydrogen bonds such as carbon-hydrogen bonds, nitrogen-hydrogen bonds, and mercapto groups that can be abstracted by radicals, and carbon-carbon double bonds obtained by copolymerization 1) are used. It is preferable to have. This is because when the polymerizable monomer undergoes a radical polymerization reaction, it grafts onto the added resin having graft active sites to form a graft polymer, which has the effect of improving mutual compatibility between the resins. It is possible to further improve the appearance, gloss, texture, etc. Also,
Among the crosslinking agents described below, those that dissolve in monomers to provide appropriate viscosity and contribute to pigment dispersion and stability may be used as the [resin].

For example, aminoplast resins and blocked polyisocyanate resins are representative. The resin in these liquid pigment dispersion compositions imparts appropriate viscosity to the system and adds Sure to facilitate dispersion during pigment dispersion. Further, the resin is adsorbed onto the surface of the pigment to facilitate the dispersion of the pigment, and is also useful during subsequent suspension polymerization in terms of maintaining the dispersion stability of the pigment. Furthermore, since liquid pigment dispersion compositions containing such resins have viscosity, polymerizable monomers that are soluble in water or have a high solubility in water, such as those having hydroxyl groups, etc. Since migration to the aqueous layer is prevented during suspension polymerization, raw material loss is reduced and good stability of the dispersed particles is maintained. Furthermore, these resins also contribute to improving various properties of the cured coating film, such as appearance, gloss, texture, flexibility, and hardness. The amount of such resin used is
Usually, it is preferable to select the amount in the range of about 3 to 60% by weight in the liquid pigment dispersion composition.

If the amount used is less than about 3% by weight, the dispersion retention of the pigment decreases, and if it exceeds about 60% by weight, the viscosity increases, making it difficult to handle. Crosslinking agents D used in the present invention include aminoplast resins, phenolic resins, polyamines, blocked polyisocyanate compounds,
Typical examples include organic compounds having more than one carboxyl group. By adding these crosslinking agents, thermosetting properties are imparted to the pigment dispersion composition produced by suspension polymerization, and the resulting cured coating film has good gloss, mechanical strength, and flexibility. Various properties such as flexibility, water resistance, acid resistance, alkali resistance, corrosion resistance, and weather resistance are improved. Examples of the above aminoplast resin and phenolic resin include urea,
Examples include amino compounds such as melamine and guanamines, condensates of phenols and formaldehyde, and ether compounds of these with alcohols.

These are usually 100% of the resin component in the liquid pigment dispersion composition.
It may be used in a range of 5 to 40 parts by weight. Baking temperature when using aminoplast resin is 80
~220°C is desirable. Examples of the above-mentioned blocked polyisocyanate compounds include polyvalent isocyanates (hexamethylene diisocyanate, tolylene diisocyanate, etc.), low-molecular polyol adducts thereof, or polyisocyanates having a biuret structure or an allophanate structure. Examples include addition products with blocking agents (phenols, alcohols, lactams, active methylene compounds, amines, oximes, etc.).

These are usually 100% of the resin component in the liquid pigment dispersion composition.
It may be used in a range of 5 to 60 parts by weight. When used, it is preferable to use a dissociation catalyst such as a base (triethylamine, N-methylmorpholine, etc.) or a metal compound (dibutyltin dilaurate, stannous tin chloride, etc.) in combination. The baking temperature is preferably 120 to 220°C. Examples of the organic compounds having two or more carboxyl groups include polycarboxylic acids (adipic acid, sebacic acid, phthalic acid, trimellitic acid, etc.) and polyester resins obtained by the condensation reaction of excess polycarboxylic acid and polyol. Can be mentioned.

These are usually 100% of the resin component in the liquid pigment dispersion composition.
It may be used in a range of 3 to 50 parts by weight. The equivalent ratio of the epoxy group in the resin component to the carboxyl group in the crosslinking agent is preferably adjusted to 0.8 to 1.2. The baking temperature is preferably 120 to 220°C. The above pigment A) polymerizable monomer mixture B, resin C,
And if necessary, dispersion aid is added all at once, and the pigment is finely pulverized and dispersed by applying it to a dispersion machine to obtain a dispersion paste. In addition, additives such as a wetting agent, a coating surface conditioner, a curing aid, and an antioxidant are mixed in to prepare a liquid pigment dispersion composition.

If the crosslinking agent contributes to the pulverizing effect of the pigment, it may be added before being applied to the disperser. Furthermore, regarding the above adjustment method,
It is more advantageous to previously perform bulk polymerization of the dispersed paste pulverized and dispersed by the above-mentioned disperser at a temperature of about 80 to 150° C. at a polymerization rate of 30 to 100%. By employing such bulk polymerization, the resin component is firmly adsorbed onto the pigment surface, which contributes to maintaining stable dispersion of the pigment. Also,
Even if dispersion is started with a polymerizable monomer and a pigment, polymerization may proceed to some extent at the end of dispersion, resulting in a liquid dispersion composition containing the polymerizable monomer, resin, and pigment.

Furthermore, a liquid dispersion composition obtained by simply dissolving a pigment dispersion composition in which a pigment is previously dispersed in a resin in a polymerizable monomer can also be used. As a device for dispersing, a dispersing machine used in the conventional paint and ink industries for manufacturing paints and inks can be used. Examples include roll mills, colloid mills, fluid energy dispersion machines, vibrating ball mills, ball mills, sand gliders, and the like. These dispersion conditions are not particularly different from those for ordinary solvent-based paints, and an appropriate dispersion time is selected depending on the type of disperser and the required degree of dispersion. polymerizable monomer,
During dispersion of a mixed solution of resin and pigment, a polymerization inhibitor such as hydroquinone or 2,2'-diphenyl-1-picrylhydrazyl is added to prevent the contained polymerizable monomers from polymerizing. You may. However, if the polymerization progresses to some extent during dispersion and does not interfere with the dispersion operation, the above-mentioned polymerization inhibitor may not be added. Additives commonly used in paints, inks, etc., such as pigments, wetting agents, coating surface conditioners, curing aids, and antioxidants, may be added to the mixed solution as necessary during or before the dispersion. It can also be added within a range that does not interfere with polymerization or bulk polymerization. The suspension polymerization method carried out in the present invention can be a normal suspension polymerization method, except that polyethylene glycol having a molecular weight of 100,000 to 300,000 is used as a suspension stabilizer.

For example, the concentration range of the suspension stabilizer in an aqueous medium does not impair its suspension stability (for example, 0.5 to 10% by weight).
The specific gravity of the aqueous medium,
Other additives besides suspension stabilizers can also be used to adjust surface tension, viscosity, or reduce the solubility of easily soluble polymerizable monomers. As such additives, salts such as sodium chloride, potassium chloride, and sodium sulfate are used.
In addition, when using such salts, since they tend to change at least the cloud point of the above-mentioned suspension stabilizer, it is necessary to consider so as not to interfere with the suspension stabilizing power. Thus, they also reduce the solubility of water in the polymerizable monomers and serve to improve the transparency of the resin component. The above-mentioned liquid pigment dispersion composition is added to the above-mentioned aqueous medium in the presence of a polymerization initiator, and the temperature is maintained at about 20 to 100°C, preferably about 50 to 90°C, while stirring and dispersing the composition to react. .

By subjecting the thus obtained suspended product to simple washing and separation treatments (e.g. filtration, centrifugation),
A desired pigment dispersion composition for thermosetting coating is produced.

In general, when such polyethylene glycol has a large molecular weight, it exhibits an aggregation effect, which tends to impair the suspension stabilizer.On the other hand, when the molecular weight is too low, its effectiveness as a suspension stabilizer decreases. 100000~3
A range of 00000 is desirable.

Furthermore, in use, the effect of the compound as a suspension stabilizer differs slightly depending on the viscosity of the liquid pigment dispersion composition to be suspended, so the amount of the compound to be used, It is also important to consider molecular weight, use of other auxiliaries, etc. As the polymerization catalyst, ordinary radical polymerization initiators such as organic peroxides such as besozoyl peroxide and lauroyl peroxide, azobisnitriles such as azobisisobutyronitrile, and persulfate salts such as potassium persulfate are used. Can be used.

In addition, in order to adjust the molecular weight, conventional molecular weight regulators, such as mercaptans such as primary or tertiary dodecyl mercaptan, disulfides such as diisopropylsantogen disulfide, diazothioethers, etc.
A halogenide or the like may be used in an amount of less than 5% by weight in the reaction system. The thermosetting pigment dispersion composition for coating obtained as described above can be used as a coloring agent for various plastics.

Furthermore, the composition can be suitably used for slurry paints and powder paints. That is, the particle size is 100μ
In the above cases, after being subjected to an appropriate pulverization treatment, if it is less than 100 μm, it can be used as it is as a slurry paint in the presence of an aqueous medium. In addition, when used in this slurry paint, a suitable amount of ordinary organic solvents, water-soluble paints, emulsion paints, etc. may be used in combination. When used as a powder coating, the composition may be appropriately dried and pulverized, or the above-mentioned slurry coating may be dried as is. In this case, the glass transition temperature of the resin particles is preferably in the range of about 5 to 100°C. When the glass transition temperature is less than about 5°C, it may be difficult to maintain the powder state of the paint at room temperature, and it may be difficult to maintain the powder state of the paint at room temperature.
If the temperature exceeds 0°C, the fluidity during baking of coating film formation tends to be poor, making it difficult to obtain a smooth cured coating film. The pigment dispersion composition for thermosetting coating produced by the method of the present invention having the above-mentioned structure has important properties such as gloss, thermal fluidity, thermal stability, etc., which are inhibited by the suspension stabilizer, especially for slurry paints and powder paints. Therefore, it is fully applicable to slurry paints and powder paints, and it is possible to form cured paint films with good appearance and performance.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples.

Note that "parts" and "%" in the example sentences mean "parts by weight" and "% by weight." Further, the contents of the [alkyd resin having a mercapto group] as the resin C used below are as follows. Example 1 A liquid mixture consisting of 10 parts of an alkyd resin having a mercapto group, 10 parts of n-butyl methacrylate and 19 parts of styrene is obtained.

Mixing 6 parts of the above liquid mixture, 7.95 parts of methyl methacrylate and 4.83 parts of glycidyl methacrylate,
Titanium white (trade name: "Ti-Pure" manufactured by Dupont) was added to this.
40 parts of t-dodecyl mercaptan were added and dispersed with a sand grind mill until the pigment coarse particle size was 10 μm or less, and then 0.8 part of t-dodecyl mercaptan was added and mixed, and this was charged into a Kolben.

The contents were heated from room temperature to 90°C over 15 minutes with stirring, and 3 parts of the above liquid mixture, 4 parts of methyl methacrylate,
A mixed solution consisting of 2.43 parts of glycidyl methacrylate, 0.2 parts of azobisisobutyronitrile, and 0.4 parts of t-dodecylmercabutane is added dropwise over a period of 1 hour (the temperature is increased from 90°C to 140°C at the start of dropping). Raise the temperature and maintain the same temperature until the end of the dropwise addition to effect bulk polymerization). After the dropwise addition was completed, the mixture was stirred for about 30 minutes while being slowly cooled, and then heated to 140°C or below to add 23.7 parts of methyl methacrylate, 14.4 parts of glycidyl methacrylate, 24 parts of the above liquid mixture, 2.3 parts of t-dodecyl mercaptan, and 1.10 parts of t-dodecyl mercaptan. -decanedicarboxylic acid 1
4 parts and 2.53 parts of 2,2'-azobis-2,4-dimethylvaleronitrile were added and thoroughly stirred to prepare a liquid pigment dispersion composition. Next, the above Kolben was given a molecular weight of 2
400 parts of an aqueous medium consisting of 40 parts of polyethylene glycol having a molecular weight of 00,000 to 250,000, 4 parts of a surfactant "Amit 105" manufactured by Kioh Atlas Co., Ltd., and 356 parts of ion-exchanged water are charged, and suspension polymerization is started.

After reacting at 70°C for 5 hours, the suspended product was separated using a centrifuge, and a bead-shaped thermosetting coating pigment dispersion composition with a particle size of 5 to 50μ (glass transition temperature of resin particles of 68.8 ℃
).

Half of the above pigment dispersion composition for thermosetting coatings is diluted with ion-exchanged water to make a slurry paint, which is spray-painted onto an iron plate and baked at 180°C for 30 minutes, resulting in a smooth and glossy cured paint. is formed.

In addition, the remaining amount of the thermosetting pigment dispersion composition for coating is sufficiently dried to form a powder coating, which is coated on an iron plate and baked at 180°C for 30 minutes, resulting in a smooth and glossy cured coating. A film is formed.

Comparative Example 1 Suspension polymerization was carried out under the same conditions as in Example 1 except that 400 parts of a 1% Metrose aqueous solution was used as the aqueous medium.
Centrifugation is performed to obtain a bead-shaped thermosetting pigment dispersion composition for coating with a particle size of 5 to 50 μm.

The above pigment dispersion composition for thermosetting coatings was made into a slurry paint or a powder paint in the same manner as in Example 1, and a cured paint film was formed, but both had no gloss at all and were poor in smoothness. .

Example 2 6 parts of the liquid mixture of Example 1, 5 parts of methyl methacrylate, 4 parts of n-butyl acrylate, 2 parts of n-butyl methacrylate, and 5 parts of glycidyl methacrylate were mixed, and 30 parts of the titanium white of Example 1 was added thereto. In addition, the pigment was dispersed with a sand grind mill until the coarse particle size was 10 μm or less, and then 0.8 part of t-dodecyl mercaptan was added and mixed, and this was charged into a Kolben.

The contents were heated from room temperature to 90°C over 20 minutes with stirring, and to this were added 3 parts of the liquid mixture of Example 1, 2 parts of methyl methacrylate, 2.5 parts of glycidyl methacrylate, 2 parts of n-butyl acrylate, and n-butyl. A mixed solution consisting of 1 part of methacrylate and 0.4 part of t-dodecyl mercaptan is added dropwise over a period of 1 hour.
Raise the temperature to 40°C and maintain the same temperature until the end of the dropwise addition to perform bulk polymerization). After the dropwise addition was completed, the mixture was stirred for about 30 minutes while slowly cooling, and then 12 parts of methyl methacrylate was added at 140°C or lower.
13.5 parts of glycidyl methacrylate, 6 parts of n-butyl acrylate, 3 parts of n-butyl methacrylate, 24 parts of the liquid mixture of Example 1, 2.
2 parts, 13 parts of 1.10-decanedicarboxylic acid and 2,
2'-azobis-2,4-dimethylvaleronitrile2.
Add 5 parts and stir thoroughly to prepare a liquid pigment dispersion composition. Next, 20 parts of polyethylene glycol with a molecular weight of 150,000 to 200,000, 0.8 part of a surfactant (trade name "Solomon" manufactured by Hakuyosha Co., Ltd.) and 37 parts of ion-exchanged water were added to the above Kolben.
Suspension polymerization is started by charging 400 parts of an aqueous medium consisting of 9.2 parts.

After reacting at 70°C for 5 hours, the suspended product was separated using a centrifuge, and a bead-shaped thermosetting pigment dispersion composition for a thermosetting coating with a particle size of 200 to 500μ (glass transition temperature of resin particles of 35
．． 5°C).

The above pigment dispersion composition for thermosetting coating was diluted approximately 5 times with ion-exchanged water and ground in a pot mill for a day and night.
Pass through a mesh sieve to remove coarse particles, with an average particle size of 10 to 2.
A suspension containing irregularly shaped particles of 0 μm was obtained, which was then concentrated in a centrifuge to a non-volatile content of approximately 40% to form a slurry paint, which was then spray painted onto an iron plate and baked at 180°C for 30 minutes. , a smooth and glossy cured coating is formed.

Comparative Example 2 When carrying out the same procedure as in Example 2 except that polyethylene glycol having a molecular weight of about 6000 is used, a suspension-stable bead-shaped pigment dispersion composition for thermosetting coating cannot be obtained.

Example 3 2 parts of an alkyd resin having a mercapto group, 5.98 parts of methyl methacrylate, 2.97 parts of styrene, 4.03 parts of n-butyl acrylate and 5.01 parts of 2-hydroxyethyl methacrylate were mixed, and the Add 30 parts of the titanium white from Example 1 and use a sand grind mill to make the pigment coarse particle size 1.
Disperse until the particle size becomes 0μ or less, then add and mix 0.6 part of t-dodecylmercaptan, and charge this into a Kolben.

The contents were heated from room temperature to 90°C over 15 minutes while stirring, and added with 0.5 parts of alkyd resin having a mercapto group, 1.5 parts of methyl methacrylate, 1.25 parts of 2-hydroxyethyl methacrylate, and azobisisomer. Butyronitrile 0.
2 parts, 0.74 parts of styrene, 1 part of n-butyl acrylate
．． A mixed solution consisting of 1 part of t-dodecyl mercaptan and 046 parts of t-dodecyl mercaptan is added dropwise over a period of 1 hour (the temperature is raised from 90°C to 140°C at the start of the dropwise addition, and the same temperature is maintained until the end of the dropwise addition to effect bulk polymerization). After dropping, slowly cool down to approx.
Stir for 0 minutes, then add 13.4 parts of methyl methacrylate, 11.25 parts of 2-hydroxyethyl methacrylate, and 4.5 parts of alkyd resin having a mercapto group at 140°C or lower.
parts, 0.7 parts of t-dodecylmercabutane, 20.3 parts of protoxyisocyanate, 6.66 parts of styrene, 9.09 parts of n-butyl acrylate, 0 parts of dibutyltin dilaurate.
, 5 parts and 1.5 parts of 2,2'-azobis-2,4-dimethylvaleronitrile were added and thoroughly stirred to prepare a liquid pigment dispersion composition. Next, 400 parts of an aqueous medium consisting of 32 parts of polyethylene glycol having a molecular weight of 150,000 to 200,000 and 368 parts of ion exchange were separately charged into 17 leu for 11, and the above liquid pigment dispersion composition was added while stirring to carry out suspension polymerization. Start.

After reacting at 70°C for 5 hours, the suspended product was separated using a centrifuge, and a bead-shaped thermosetting pigment dispersion composition for a thermosetting coating with a particle size of 200 to 500 μm (glass transition temperature of resin particles of 37
．． 8°C).

The above thermosetting pigment dispersion composition for coating was made into a suspension and then a slurry paint in the same manner as in Example 2, and a cured paint film was formed from this, and the paint film was smooth and glossy. .

In addition, the suspension before making the slurry paint was dried to make a powder paint, and this was electrostatically coated on an iron plate for 30 minutes at 180°C.
After baking for a few minutes, a smooth, glossy cured film is formed.

Example 4 2 parts of alkyd resin having a mercapto group, 8 parts of methyl methacrylate, 8 parts of styrene, 2 parts of n-butyl methacrylate and 5 parts of 2-hydroxyethyl methacrylate were mixed, and 30 parts of the titanium white from Example 1 was added to the mixture. In addition, the pigment was dispersed with a sand grind mill until the coarse particle size was 10μ or less, and then 0.6 part of t-dodecylmercaptan was added.
Mix and pour this into the kolben.

The contents were heated from room temperature to 90°C over 15 minutes with stirring, and to this were added 1 part of alkyd resin having a mercapto group, 4 parts of methyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, and 0.2 parts of azobisisobutyronitrile. A mixed solution consisting of 2 parts of styrene, 1 part of n-butyl methacrylate, and 0.2 parts of t-dodecyl mercabutane is added dropwise over a period of 1 hour. Maintain the same temperature until the end of bulk polymerization).
After the addition was completed, the mixture was stirred for about 30 minutes while gradually cooling, and then 1
At 40°C or below, 13 parts of methyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 5 parts of alkyd resin having a mercapto group, 0.8 parts of t-dodecyl mercaptan, 21 parts of pro-isocyanate, 9 parts of styrene, n-
4 parts of butyl methacrylate, 0 parts of dibutyltin dilaurate
．． 5 parts of 2,guazobis-2,4-dimethylvaleronitrile were added and stirred sufficiently to prepare a liquid pigment dispersion composition. Next, the above Kolben was given a molecular weight of 20
32 parts of polyethylene glycol, Example 1
4 parts of a surfactant and 400 parts of an aqueous medium consisting of 364 parts of ion-exchanged water were charged, and suspension polymerization was started. 70
After reacting at ℃ for 5 hours, the suspended product was separated using a centrifuge, and a bead-shaped thermosetting coating pigment dispersion composition with a particle size of 5 to 50μ (glass transition temperature of resin particles of 7'C) was obtained. get.

The thermosetting pigment dispersion composition for coating was made into a slurry paint or a powder paint in the same manner as in Example 1, and when cured paint films were formed, all the paint films were smooth and glossy.

Example 5 8 parts of the liquid mixture of Example 1, 8 parts of methyl methacrylate, 6 parts of styrene, 1 part of n-butyl acrylate, 2 parts of n-butyl methacrylate and 3 parts of hydroxypropyl methacrylate were mixed, and a red pigment (large 8 parts of Nippon Ink Kogyo Co., Ltd. (trade name "Corofain Red 236") were added and dispersed with a sand grind mill until the pigment coarse particle size was 10μ or less, and then t-dodecylmercaptan O,
Add 5 parts, mix and charge this to a Kolben.

The contents were heated from room temperature to 90°C over 15 minutes with stirring, and to this were added 4 parts of the liquid mixture of Example 1, 3 parts of styrene, 1 part of n-butyl methacrylate, 1.5 parts of hydroxypropyl methacrylate, and t-dodecyl. Mercaptan 0.3
(The temperature is raised from 90° C. to 140° C. at the start of dropping and maintained at the same temperature until the end of dropping to effect bulk polymerization.) After the dropwise addition was completed, the mixture was stirred for about 30 minutes while slowly cooling, and then at 140°C or lower, 28 parts of methyl methacrylate, 21 parts of styrene, 3.5 parts of n-butyl acrylate, 7 parts of n-butyl methacrylate, and 10.5 parts of hydroxypropyl methacrylate were added. 1.5 parts of mercabutane, melamine-formaldehyde resin (trade name [CyOl-303] manufactured by American Cyanamid)
20 parts, 0.5 part of dibutyltin dilaurate and 2,
2! -Azobis-2,4-dimethylvaleronitrile3.
Add 5 parts and stir thoroughly to prepare a liquid pigment dispersion composition.

Next, 400 parts of an aqueous medium consisting of 20 parts of polyethylene glycol having a molecular weight of 150,000 to 200,000, 2 parts of the surfactant of Example 1, and 378 parts of ion-exchanged water are charged into the above Kolben, and suspension polymerization is started.

After reacting at 70°C for 5 hours, the suspended product was separated using a centrifuge and a bead-shaped thermosetting coating pigment dispersion composition with a particle size of 200 to 500μ (glass transition temperature of resin particles of 63
℃) is obtained. The above thermosetting pigment dispersion composition for coating was made into a suspension and then a slurry paint in the same manner as in Example 2,
When a cured coating film was formed from this, the coating film was smooth and glossy.

In addition, the suspension before making the slurry paint was dried to make a powder paint, which was then electrostatically coated on an iron plate for 30 minutes at 180°C.
After baking for 0 minutes, a smooth and glossy cured coating is formed.

Comparative Example 3 When carried out in the same manner as in Example 5 except that polyethylene glycol having a molecular weight of about 540,000 to 600,000 was used, the suspension product agglomerated and a suspension-stable pigment dispersion composition for thermosetting coating was obtained. I can't get it.

Claims (1)

[Scope of Claims] 1 Pigment A, containing 5 to 40% by weight of at least one selected from the group of (1) a polymerizable monomer having a hydroxyl group and (2) a polymerizable monomer having a glycidyl group. In a method for producing a pigment dispersion composition for thermosetting coating by suspension polymerizing a liquid pigment dispersion composition containing a polymerizable monomer mixture B, an alkyd resin C, and a crosslinking agent D in an aqueous medium, the above-mentioned polymerization As a suspension stabilizer when the molecular weight is 100,000 to 3
1. A method for producing a pigment dispersion composition for thermosetting coatings, characterized in that polyethylene glycol of 0.00000 is used. 2. The method according to item 1 above, wherein the liquid pigment dispersion composition to be subjected to suspension polymerization is subjected to bulk polymerization in advance.