JPH0140847B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an acrylic resin for paints that has excellent pigment dispersion stability and coating film performance. Conventionally, acrylic resins have been widely used as paint resins that have excellent performance in terms of stain resistance, chemical resistance, weather resistance, etc. of paint films. However, acrylic resins generally have poor pigment dispersibility, and have the drawback of being prone to problems such as thickening during pigment kneading, pigment sedimentation due to aggregation of primary color paints, and color separation in toning paints. In order to improve these drawbacks, for example, methods of polymerizing acrylic resins in the coexistence of animal and vegetable oil-modified alkyd resins with good pigment dispersibility (for example, Japanese Patent Application Laid-Open No. 45084-1984) and unsaturated oil-free alkyd resins have been proposed. A method of polymerization in the coexistence of a resin (for example, Japanese Patent Publication No. 53-766) has been reported. but,
In these methods, since an alkyd resin is introduced as a second component, there is a problem in that it becomes difficult to maintain the excellent coating film performance (for example, stain resistance, chemical resistance, etc.) possessed by acrylic resins. Another method is to use unsaturated tertiary monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate as monomers that have affinity with pigments when producing acrylic resins.
A method of copolymerization using class amines (for example,
Tokuko Sho 53-3409) has been reported. However, although these methods can to some extent solve problems such as thickening during pigment mixing and pigment settling due to agglomeration of primary color paints, there are problems such as color separation in toning paints cannot be completely resolved. . The present inventors conducted research to obtain an acrylic resin for paint that overcomes these drawbacks, and as a result,
The present invention has been completed by developing a method for producing an acrylic resin for paint that can solve the above problems. That is, in the method for producing an acrylic resin for paint according to the present invention, an α,β-unsaturated carboxylic acid and an alkylene oxide are combined with the general formula (a). (However, in the formula, R ₁ is a hydrogen atom or a methyl group,
R ₂ and R ₃ each represent a methyl group or an ethyl group,
n represents an integer of 1 or 2. ) 0.1 to 40 parts by weight of a reaction mixture obtained by reacting in the presence of a catalyst represented by () and a vinyl monomer () 99.9 to 60 containing 10% by weight or more of a (meth)acrylic monomer. Parts by weight are copolymerized. Here, the (meth)acrylic monomer means acrylic acid, methacrylic acid, or esters of these acids. In this specification, (meth)acrylic acid collectively refers to acrylic acid and methacrylic acid, and (meth)acrylate refers to acrylate and methacrylate, respectively. Examples of the α,β-unsaturated carboxylic acid used in the production of the reaction mixture () in the present invention include (meth)acrylic acid, and examples of the alkylene oxide include ethylene oxide and propylene oxide. The charging ratio for the reaction between α, β-unsaturated carboxylic acid and alkylene oxide may be selected arbitrarily, but considering the ease of reaction and the remaining amount of alkylene oxide, α,
β-unsaturated carboxylic acid/alkylene oxide =
It is desirable to carry out the reaction in an amount within the range of 1/0.9 to 1/1.3 (molar ratio). Examples of the catalyst represented by the general formula (a) used in the production of the reaction mixture () include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and the like. The amount of catalyst used is
Based on 100 parts by weight of α,β-unsaturated carboxylic acid
The amount ranges from 0.01 to 10 parts by weight, preferably from 0.1 to 5 parts by weight. Generally, saturated tertiary amines such as triethylamine and tributylamine; metals such as iron, chromium, and nickel, or their salts are reported as catalysts used for the reaction between α,β-unsaturated carboxylic acids and alkylene oxides. However, if the reaction mixture obtained by using these catalysts is used instead of the reaction mixture () of the present invention, it will not be possible to obtain an acrylic resin with excellent pigment dispersibility, which is the object of the present invention. It can't be. The reaction mixture () is prepared by introducing an alkylene oxide into a mixture of an α,β-unsaturated carboxylic acid and a catalyst represented by the general formula (a), and then reacting the mixture for 30 to 30 minutes under normal pressure or increased pressure.
It is obtained by heating to a temperature of 120°C, preferably 50 to 100°C for reaction. In order to prevent polymerization, the reaction is preferably carried out under an air stream and a polymerization inhibitor is added. As a polymerization inhibitor,
For example, hydroquinone, hydroquinone monomethyl ether, t-butylhydroxyanisole, p-nitrophenol, phenothiazine, etc. are used, and the amount used is 0.01 to 0.1 part by weight per 100 parts by weight of α,β-unsaturated carboxylic acid. Amounts within the range are preferred. The resulting reaction mixture ()
is used as a copolymerization component without being purified by distillation. If the main fraction obtained by distillation purification is used as a copolymerization component, an acrylic resin having excellent pigment dispersibility, which is the object of the present invention, cannot be obtained. However, it is possible to remove excess unreacted alkylene oxide from the reaction mixture (2) by air blowing, vacuum distillation, or the like. The amount of the reaction mixture () to be used is in the range of 0.1 to 40 parts by weight, based on 100 parts by weight of the total of the reaction mixture () and the vinyl monomer ().
If the amount is less than 0.1 part by weight, the resulting resin will not exhibit good pigment dispersibility. Moreover, if the amount exceeds 40 parts by weight, the coating film performance (for example, water resistance, stain resistance, etc.) of the resulting resin will decrease. It is unclear why the acrylic resin for paints obtained by the production method of the present invention has excellent paint film performance and excellent pigment dispersibility. Attempts have been made to improve pigment dispersibility by copolymerizing unsaturated tertiary amines as a component of vinyl monomers, but these methods have problems with pigment kneading suitability and pigment dispersion in primary color paints. As mentioned above, although the stability can be improved, there are problems such as the inability to improve the pigment dispersion stability in toning paints. Further, as a comparison with the present invention, the present inventors first converted an α,β-unsaturated carboxylic acid and an alkylene oxide into the above general formula.
A reaction mixture is obtained using a catalyst other than the catalyst represented by (a) (e.g., triethylamine, iron powder), and the catalyst represented by the above general formula (a) is added to the reaction mixture, which is the other copolymerization component. Although copolymerization with a vinyl monomer () was attempted, the resulting resin did not exhibit the excellent pigment dispersibility that is the objective of the present invention. This point will be explained in more detail in Examples and Comparative Examples below. Therefore, the excellent pigment dispersibility of the acrylic resin for paint obtained by the production method of the present invention is due to the specific ratio of the reaction mixture () and the vinyl monomer (), which are the raw material components of the acrylic resin. This is thought to be due to the interaction of The vinyl monomer (), which is another component for obtaining the acrylic resin for paint in the production method of the present invention, contains 10% by weight or more of a (meth)acrylic monomer. Examples of (meth)acrylic monomers include (meth)acrylic acid; methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, 2-ethylhexyl ( Ester compounds of monohydric alcohols such as meth)acrylate and lauryl(meth)acrylate and (meth)acrylic acid; ) Monoester compounds with acrylic acid; dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, etc. Diester compounds with (meth)acrylic acid: glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, etc. Polyester compounds of polyhydric alcohol and (meth)acrylic acid such as: amino group-containing (meth)acrylates such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate; glycidyl (meth)acrylate, etc. One or more types selected from these groups can be effectively used. If the amount of (meth)acrylic monomer in the vinyl monomer () is less than 10% by weight, the coating film performance of the resulting acrylic resin for paints (e.g. weather resistance,
(chemical resistance, etc.) is undesirable. The type of these (meth)acrylic monomers and the amount used within the above range are appropriately determined depending on the desired coating suitability and coating film performance. Other monomers used as the vinyl monomer () include, for example, aromatic vinyl hydrocarbons such as styrene, chlorostyrene, vinyltoluene, and divinylbenzene; vinyl acetate, vinyl propionate, vinyl benzoate, Vinyl ester compounds of monovalent carboxylic acids such as vinyl versatate; Unsaturated amides or derivatives thereof such as (meth)acrylamide, diacetone acrylamide, and methylolated (meth)acrylamide; Unsaturated cyanogens such as (meth)acrylonitrile and crotonitrile Compounds; (meth)unsaturated alcohols such as allyl alcohol and croton alcohol; (meth)
Unsaturated glycidyl ethers such as allyl glycidyl ether; unsaturated dibasic acids such as maleic acid, fumaric acid, itaconic acid, and dimer acid; monohydric alcohols and unsaturated dibasic acids such as monomethyl maleate and monoallyl maleate. monoesters with; examples include olefinic hydrocarbons such as ethylene, propylene, butadiene, isoprene, vinyl chloride, vinylidene chloride, and halogen-substituted products thereof; one or more selected from these groups; It can be used effectively. In the production method of the present invention, the acrylic resin for paint is obtained by copolymerizing 0.1 to 40 parts by weight of the reaction mixture () and 99.9 to 60 parts by weight of the vinyl monomer (). , an animal (vegetable) oil-modified alkyd resin or an unsaturated oil-free alkyd resin may be copolymerized. Copolymerization of the reaction mixture () and the vinyl monomer () can be carried out by ordinary radical copolymerization, and thereby an acrylic resin for paint can be easily obtained. The copolymerization reaction is preferably carried out by solution polymerization using an organic solvent. Examples of organic solvents include aromatic hydrocarbons such as toluene and xylene; acetate esters such as ethyl acetate, butyl acetate, and acetate ester of ethylene glycol monoethyl ether; ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexane. ; Aliphatic alcohols such as isopropanol, n-butanol, i-butanol;
Examples include alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and diethylene glycol monoethyl ether, and these organic solvents may be used alone or as a mixed solvent. However, if the acrylic resin for paint obtained by the production method of the present invention is to be used in combination with a crosslinking agent such as a polyisocyanate compound or a blocked polyisocyanate compound, the above-mentioned aliphatic alcohols or alkylene glycols may be used. Solvents that are active toward isocyanate groups, such as monoalkyl ethers, are not preferred. In the copolymerization reaction, commonly known free radical catalysts such as azobisisobutyronitrile, benzoyl peroxide, ditertiary-butyl peroxide, cumene hydroperoxide, etc. are used as the polymerization catalyst. These polymerization catalysts are used in amounts in proportions ranging from 0.1 to 10% by weight, based on the total weight of the reaction mixture () and the vinyl monomer (). Furthermore, in order to adjust the molecular weight of the acrylic resin for coatings obtained by the copolymerization reaction, a chain transfer agent or regulator such as lauryl mercaptan, 2-mercaptoethanol, carbon tetrachloride, carbon tetrabromide, etc. may be used. . The acrylic resin for coatings obtained by the production method of the present invention can be prepared using various commonly used diluting solvents, pigments, fillers, curing catalysts, etc. according to the required coating suitability and coating performance. Various paint additives, modifying resins (for example, alkyd resins, epoxy resins, cellulose derivatives, chlorinated rubber, etc.), etc. can be appropriately blended and used. Further, the acrylic resin for paint obtained by the production method of the present invention can be used as a crosslinked and cured paint by using it in combination with various crosslinking agents. Examples of crosslinking agents include aminoplast resins such as methyl etherified melamine resin, butyl etherified melamine resin, and butyl etherified benzoguanamine resin; hexamethylene diisocyanate, toluene diisocyanate, xylylene diisocyanate, cresol-blocked products of toluene diisocyanate, and xylylene diisocyanate. Examples include polyisocyanate compounds such as n-butanol blocked products, and blocked products thereof. These crosslinking agents are α, β in the reaction mixture ().
-Creates a crosslinking reaction with the reaction product of unsaturated carboxylic acid and alkylene oxide. Also (meta)
If a (meth)acrylate having a hydroxyl group (for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.) is used as the acrylic monomer, it will also react with the crosslinking agent and cause intermolecular crosslinking. form. The paints obtained using the acrylic resin for paints obtained by the production method of the present invention are free from pigment sedimentation in primary color paints, with respect to various pigments such as titanium oxide, carbon black, phthalocyanine blue, Bengara, yellow flower, etc. It has excellent pigment dispersibility and does not cause color separation in toning paints.
Furthermore, the coating material can be applied to the surface of various coated substrates (for example, metals such as iron and aluminum, plastics, slate, etc.) by various known methods, and can exhibit excellent coating film performance. Hereinafter, the present invention will be explained in more detail with reference to Production Examples, Comparative Production Examples, Examples, and Comparative Examples. In addition, parts in the examples indicate parts by weight, and % indicates weight %. Production Example 1 Acrylic acid 144 was added to a reactor equipped with a stirrer, reduction condenser, dropping funnel, thermometer and gas injection pipe.
part, dimethylaminoethyl methacrylate 4.0
1 part and 0.05 part of hydroquinone monomethyl ether, and brought the liquid temperature to 70℃ under stirring and air flow.
The temperature rose to . 122 parts of propylene oxide was added dropwise thereto over 3 hours, and the reaction was continued for an additional 5 hours.
During this time, the liquid temperature was maintained at 70°C. Next, the liquid temperature was raised to 100°C, and the reaction was continued at this temperature for 2 hours, and then the temperature was lowered. The reaction mixture thus obtained had an acid value of 10 mgKOH/g and a hydroxyl value of 345 mg.
It was a colorless transparent liquid substance (hereinafter referred to as [reaction mixture A]) containing KOH/g. Production Example 2 Into the same reactor used in Production Example 1, 172 parts of methacrylic acid, 4.8 parts of diethylaminoethyl methacrylate, and 0.06 parts of hydroquinone monomethyl ether were charged, and the liquid temperature was brought to 70°C under stirring and an air stream. The temperature rose. 122 parts of propylene oxide was added dropwise thereto over 3 hours, followed by reaction in the same manner as in Production Example 1, and then the temperature was lowered. The reaction mixture thus obtained had an acid value of 15 mgKOH/
g, a colorless transparent liquid substance (hereinafter referred to as [reaction mixture B]) with a hydroxyl value of 310 mgKOH/g. Comparative Production Example 1 Into the same reactor used in Production Example 1, 144 parts of acrylic acid, 4.0 parts of triethylamine, and 0.05 parts of hydroquinone monomethyl ether were charged, and the liquid temperature was raised to 70°C under stirring and an air stream. . 122 parts of propylene oxide was added dropwise thereto over 3 hours, and the reaction was continued for an additional 9 hours. During this time,
The liquid temperature was maintained at 70°C. The reaction mixture thus obtained was a colorless transparent liquid substance (hereinafter referred to as
It is referred to as [Comparative Reaction Mixture A]. ). Comparative Production Example 2 Into the same reactor used in Production Example 1, 144 parts of acrylic acid, 0.9 g of iron powder (particle size: 100 mesh), and 0.1 part of hydroquinone monomethyl ether were charged, and the liquid temperature was adjusted under stirring and an air stream. The temperature was raised to 70°C and heated at this temperature for 2 hours. Next, 122 parts of propylene oxide was added dropwise thereto over 3 hours, and the reaction was continued for an additional 9 hours. During this time, the liquid temperature is
The temperature was maintained at 70℃. The reaction mixture thus obtained had an acid value of 20 mgKOH/g and a hydroxyl value of 385 mg.
It was a colorless transparent liquid substance (hereinafter referred to as [comparative reaction mixture B]) containing KOH/g. Example 1 Toluene was added to the same reactor used in Production Example 1.
70 parts and 30 parts of ethyl acetate were charged, and the liquid temperature was raised to 70°C while stirring and under a nitrogen stream. There, 2.5 parts of [reaction mixture A] obtained in Production Example 1, 0.3 parts of methacrylic acid, and 72.2 parts of methyl methacrylate
A mixture of 25 parts of n-butyl acrylate and 1 part of azobisisobutyronitrile as a polymerization catalyst was continuously added dropwise over a period of 2 hours. During this time, the liquid temperature was maintained at 70°C. Further, by continuing polymerization for 4 hours at the same temperature, an organic solvent solution of acrylic resin for paint (hereinafter referred to as [resin solution 1]) was obtained.
That's what it means. ) was obtained. [Resin solution 1] has non-volatile content.
49.8%, viscosity 140 Stokes (25℃, measured by bubble viscometer. The same applies hereinafter), resin acid value 2.0mgKOH/
g, the resin was a transparent solution with a hydroxyl value of 8.5 mgKOH/g. Comparative Example 1 Toluene was added to the same reactor used in Production Example 1.
70 parts and 30 parts of ethyl acetate were charged, and the liquid temperature was raised to 70°C while stirring and under a nitrogen stream. There, 0.3 parts of methacrylic acid, 74.7 parts of methyl methacrylate
Example 1
A resin solution in an organic solvent (hereinafter referred to as [Comparative Resin Solution 1]) was obtained by dropping and polymerizing in the same manner as in the case of . [Comparative resin solution 1] was a transparent solution with a nonvolatile content of 50.0%, a viscosity of 105 Stokes, and a resin acid value of 2.1 mgKOH/g. Comparative Example 2 Toluene was added to the same reactor used in Production Example 1.
70 parts and 30 parts of ethyl acetate were charged, and the liquid temperature was raised to 70°C while stirring and under a nitrogen stream. There, 2.5 parts of [comparative reaction mixture A] obtained in Comparative Production Example 1,
0.3 parts of methacrylic acid, methyl methacrylate
A mixture of 72.2 parts of n-butyl acrylate, 25 parts of n-butyl acrylate, and 1 part of azobisisobutyronitrile was added dropwise in the same manner as in Example 1, and polymerized to form an organic solvent solution of the resin (hereinafter referred to as [Comparative Resin solution 2) was obtained. [Comparative resin solution 2] has a nonvolatile content of 50.1%, a viscosity of 127 Stokes, a resin acid value of 2.1 mgKOH/g, and a resin hydroxyl value of 8.6 mg.
It was a clear solution of KOH/g. Comparative Example 3 Toluene was added to the same reactor used in Production Example 1.
70 parts and 30 parts of ethyl acetate were charged, and the liquid temperature was raised to 70°C while stirring and under a nitrogen stream. Thereto, 2.5 parts of [comparative reaction mixture B] obtained in Comparative Production Example 2,
0.3 parts of methacrylic acid, methyl methacrylate
A mixture of 72.2 parts of n-butyl acrylate, 25 parts of n-butyl acrylate, and 1 part of azobisisobutyronitrile was added dropwise and polymerized in the same manner as in Example 1. Solution 3) was obtained. [Comparative resin solution 3] has a nonvolatile content of 49.9%, a viscosity of 120 Stokes, a resin acid value of 2.0 mgKOH/g, and a resin hydroxyl value of 8.9 mg.
It was a clear solution of KOH/g. Comparative Example 4 Toluene was added to the same reactor used in Production Example 1.
70 parts and 30 parts of ethyl acetate were charged, and the liquid temperature was raised to 70°C while stirring and under a nitrogen stream. Thereto, 2.5 parts of [comparative reaction mixture B] obtained in Comparative Production Example 2,
0.04 parts of dimethylaminoethyl methacrylate,
0.3 parts of methacrylic acid, methyl methacrylate
A mixture of 72.2 parts of n-butyl acrylate, 25 parts of n-butyl acrylate, and 1 part of azobisisobutyronitrile was added dropwise and polymerized in the same manner as in Example 1. Solution 4) was obtained. [Comparative resin solution 4] has a nonvolatile content of 49.8%, a viscosity of 122 Stokes, a resin acid value of 1.9 mgKOH/g, and a resin hydroxyl value of 9.1 mg.
It was a clear solution of KOH/g. Example 2 Toluene was added to the same reactor used in Production Example 1.
43 parts, [Reaction mixture A] 2 obtained in Production Example 1
parts, methyl methacrylate 58 parts, vinyl acetate 40 parts
1 part and 0.8 part of azobisisobutyronitrile were charged, and the liquid temperature was raised to 75° C. while stirring and under a nitrogen stream, and polymerization was carried out while maintaining this temperature for 13 hours. Thereafter, 57 parts of toluene was added to dilute the solution to obtain an organic solvent solution of an acrylic resin for paint (hereinafter referred to as "Resin Solution 2"). [Resin solution 2] has a non-volatile content of 48.1%, a viscosity of 320 Stokes,
The resin hydroxyl group was a clear solution containing 6.5 mg KOH/g. Example 3 Toluene was added to the same reactor used in Production Example 1.
43 parts, [Reaction mixture B] 2 obtained in Production Example 2
parts, methyl methacrylate 58 parts, vinyl acetate 40 parts
1 part and 0.8 part of azobisisobutyronitrile were charged, and the liquid temperature was raised to 75°C under stirring and a nitrogen stream, and polymerization was carried out in the same manner as in Example 2.
Thereafter, 57 parts of toluene was added to dilute the solution to obtain an organic solvent solution of an acrylic resin for paint (hereinafter referred to as "Resin Solution 3"). [Resin solution 3] has a non-volatile content of 48.2%, a viscosity of 332 Stokes,
The resin was a transparent solution with a hydroxyl value of 6.2 mgKOH/g. Comparative Example 5 Toluene was added to the same reactor used in Production Example 1.
43 parts, methyl methacrylate 60 parts, vinyl acetate
40 parts and 0.8 parts of azobisisobutyronitrile were charged, and the liquid temperature was raised to 75° C. while stirring and under a nitrogen stream, and polymerization was carried out in the same manner as in Example 2. Thereafter, 57 parts of toluene was added to dilute the resin to obtain an organic solvent solution of the resin (hereinafter referred to as [Comparative Resin Solution 5]). [Comparative Resin Solution 5]
was a clear solution with a non-volatile content of 48.5% and a viscosity of 278 Stokes. Example 4 Xylene was added to the same reactor used in Preparation Example 1.
80 parts and 20 parts of butyl acetate were charged, and the liquid temperature was raised to 80° C. while stirring and under a nitrogen stream. There, 12 parts of [reaction mixture A] obtained in Production Example 1, 1 part of acrylic acid, 27 parts of methyl methacrylate, 21 parts of ethyl acrylate, 18 parts of n-butyl acrylate,
A mixture consisting of 21 parts of styrene and 1 part of benziisoperoxide as a polymerization catalyst was continuously added dropwise over a period of 2 hours. During this time, the liquid temperature was maintained at 80°C. Further, polymerization was continued for 8 hours at the same temperature to obtain an organic solvent solution of an acrylic resin for paint (hereinafter referred to as [resin solution 4]). [Resin solution 4] has a nonvolatile content of 50.0%, a viscosity of 18.7 Stokes, a resin acid value of 7.6 mgKOH/g, and a resin hydroxyl value of
It was a clear solution with 52.0 mgKOH/g. Example 5 Xylene was added to the same reactor used in Preparation Example 1.
80 parts and 20 parts of butyl acetate were charged, and the liquid temperature was raised to 80° C. while stirring and under a nitrogen stream. There, 13 parts of [reaction mixture B] obtained in Production Example 2, 1 part of acrylic acid, 26 parts of methyl methacrylate, 21 parts of ethyl acrylate, 18 parts of n-butyl acrylate,
21 parts styrene and 1 part benzoyl peroxide
of the mixture was added dropwise continuously over a period of 2 hours. Hereinafter, by polymerizing in the same manner as in Example 4, an organic solvent solution of an acrylic resin for paint (hereinafter referred to as [Resin Solution 5]) was obtained. [Resin Solution 5] had a nonvolatile content of 50.5 %, a viscosity of 37.0 Stokes, a resin acid group of 8.0 mgKOH/g, and a resin hydroxyl value of 49.7 mgKOH/g. Comparative Example 6 Xylene was placed in the same reactor used in Production Example 1.
80 parts and 20 parts of butyl acetate were charged, and the liquid temperature was raised to 80° C. while stirring and under a nitrogen stream. There, 12 parts of [comparative reaction mixture A] obtained in Comparative Production Example 1,
1 part acrylic acid, 27 parts methyl methacrylate,
A mixture consisting of 21 parts of ethyl acrylate, 18 parts of n-butyl acrylate, 21 parts of styrene and 1 part of benzoyl peroxide was continuously added dropwise over 2 hours. Hereinafter, polymerization was carried out in the same manner as in Example 4 to obtain a resin solution in an organic solvent (hereinafter referred to as [Comparative Resin Solution 6]). [Comparative resin solution 6] was a transparent solution with a nonvolatile content of 50.2%, a viscosity of 12.8 Stokes, a resin acid value of 7.7 mgKOH/g, and a resin hydroxyl value of 51.7 mgKOH/g. Comparative Example 7 Xylene was added to the same reactor used in Production Example 1.
80 parts and 20 parts of butyl acetate were charged, and the liquid temperature was raised to 80° C. while stirring and under a nitrogen stream. There, 12 parts of [comparative reaction mixture B] obtained in Comparative Production Example 2,
1 part acrylic acid, 27 parts methyl methacrylate,
A mixture consisting of 21 parts of ethyl acrylate, 18 parts of n-butyl acrylate, 21 parts of styrene and 1 part of benzoyl peroxide was continuously added dropwise over 2 hours. Hereinafter, polymerization was carried out in the same manner as in Example 4 to obtain a resin solution in an organic solvent (hereinafter referred to as [Comparative Resin Solution 7]). [Comparative resin solution 7] was a transparent solution with a nonvolatile content of 49.9%, a viscosity of 10.1 Stokes, a resin acid value of 7.6 mgKOH/g, and a resin hydroxyl value of 51.5 mgKOH/g. Example 6 [Resin solution 1] to [Resin solution 5] and [Comparative resin solution 1] to [Comparative resin solution 7] obtained in Examples 1 to 5 and Comparative Examples 1 to 7 were used in the following procedure. Prepare primary color paint by kneading various pigments,
Pigment dispersibility was tested. The results are shown in Table 1.
In addition, the obtained primary color paints were mixed according to the following procedure to prepare a toning paint, and the pigment dispersibility was similarly tested. The results are shown in Table 2. As shown in Tables 1 and 2, the paints using the acrylic resin for paints obtained by the production method of the present invention have excellent pigment dispersibility in both primary color paints and toning paints. [Preparation of primary color paint] (White paint) [Resin solution 1] to [Resin solution 5] and [Comparative resin solution 1] to [Comparative resin solution 7] were each coated with white pigment “Taipeke R-820” (Ishihara Sangyo Co., Ltd.). Made by company,
Rutile type titanium oxide) was added so that the resin/pigment ratio was 1 to 1 (weight ratio), and kneaded for 30 minutes in a sand mill (using glass beads. The same applies hereinafter). This is xylene/toluene/butyl acetate = 1/1/
1 (weight ratio) thinner (hereinafter simply "thinner")
It's called. The sample was diluted to a paint viscosity of 20 seconds (Food Cup No. 4.25°C. The same applies below). (Black paint) Black pigment “FW-200” (manufactured by Degutsa, Carbon Black) was added to each of [Resin solution 1] to [Resin solution 5] and [Comparative resin solution 1] to [Comparative resin solution 7]. /pigment=1/0.04 (weight ratio)
The mixture was added and kneaded for 30 minutes using a sand mill. This was diluted with thinner in the same manner as in the preparation of the white paint described above, and used as a sample. (Blue paint) Blue pigment "Phthalocyanine Blue-4930P" was added to each of [Resin solution 1] to [Resin solution 5] and [Comparative resin solution 1] to [Comparative resin solution 7].
(manufactured by Dainichiseika Kaisha, Ltd.) was added at a resin/pigment ratio of 1/0.16 (weight ratio), and kneaded for 30 minutes in a sand mill. This was diluted with thinner in the same manner as in the preparation of the white paint described above, and used as a sample. [Preparation of toning paint] The three primary color paints of white, black, and blue obtained using each resin solution were mixed at the following blending ratios to prepare samples of toning paints. Gray color: white paint/black paint = 90/10 (weight ratio) Light blue color: white paint/blue paint = 90/10 (weight ratio)

【table】

【table】

[Table] Example 7 Among the white paints obtained in Example 6, those prepared using [Resin Solution 1] to [Resin Solution 5] and [Comparative Resin Solutions 1, 5 and 7] were used. The coating performance was evaluated. However, for the white paints prepared using [Resin Solutions 4 and 5] and [Comparative Resin Solution 7], respectively, "Super Betsukamine J-820" (butylated melamine manufactured by Dainippon Ink Chemical Co., Ltd.) was used. A 50% solution of resin) was blended at a ratio of resin/melamine resin (non-volatile content) = 75/25, and the paint viscosity was reduced with thinner.
The sample was diluted to 20 seconds. The results were as shown in Table 3. A dull steel plate with a thickness of 0.6 mm treated with Parker #144 was used as the coating base material, and each white paint was hand-sprayed onto this plate and left at room temperature for one week or baked at a temperature of 160°C for 20 minutes. This was used as a test piece. As shown in Table 3, the paint using the acrylic resin for paint obtained by the production method of the present invention is
It is comparable to the conventional paint used for comparison, and has good coating performance.

【table】

Claims (1)

[Claims] 1 α,β-unsaturated carboxylic acid and alkylene oxide represented by the general formula (a) (However, in the formula, R ₁ is a hydrogen atom or a methyl group,
R ₂ and R ₃ each represent a methyl group or an ethyl group,
n represents an integer of 1 or 2. ) 0.1 to 40 parts by weight of a reaction mixture obtained by reacting in the presence of a catalyst shown in ) and a vinyl monomer () 99.9 to 60 containing 10% by weight or more of a (meth)acrylic monomer. A method for producing an acrylic resin for paint, comprising copolymerizing parts by weight. 2 The charging ratio of α,β-unsaturated carboxylic acid and alkylene oxide is former/latter = 1/0.9 to 1/
The method for producing an acrylic resin for paint according to claim 1, wherein the molar ratio is within the range of 1.3 (molar ratio). 3 The amount of catalyst represented by general formula (a) is α, β
- The method for producing an acrylic resin for paint according to claim 1, wherein the amount is within the range of 0.1 to 10 parts by weight per 100 parts by weight of the unsaturated carboxylic acid.