JPS6121573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel and useful resin composition for powder coatings, which is a resin comprising a polyester, a glycidyl group-containing acrylic polymer, and a carboxyl group-containing vinyl polymer. The present invention relates to a composition. However, powder coatings made by combining polyester resins and acrylic resins do not exhibit sufficient physical properties and appearance. The current situation is that nothing that can be put to practical use has yet been found. However, as a result of intensive research aimed at improving these drawbacks, the present inventors have developed a polymer with a specific molecular weight obtained by the presence of (β-methyl)glycidyl (meth)acrylate, a carboxyl group-containing vinyl-based The present invention is based on the discovery of a resin composition for powder coatings that is not only compatible with polymers and specific polyester resins but also has excellent physical properties such as weather resistance of the resulting coating film. I have come to complete it. That is, the present invention provides (A) an acid value of 20 to 200 mgKOH/g and a softening point of 80 to 200 mgKOH/g;
60 to 96 parts by weight (hereinafter referred to as parts) of a polyester having a number average molecular weight of 1000 to 10000 at 150°C, (B) glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate, and β - 3 to 40 parts by weight of a polymer having a number average molecular weight of 300 to 5,000 obtained from 20 to 100% by weight of one or more compounds selected from the group consisting of methylglycidyl methacrylate and 0 to 80% by weight of other vinyl monomers. and (C) a resin composition for powder coatings comprising 1 to 20 parts by weight of a carboxyl group-containing vinyl polymer having an acid value of 10 to 200 mgKOH/g and a number average molecular weight of 300 to 10,000. It is something that provides something. First, the upper polyester (A), which is the first component of the composition of the present invention, has an acid value of 20.
~200mgKOH/g, preferably 30-70mgKOH/g
Softening point is 80~150℃, preferably 100~130℃
and the number average molecular weight is within the range of 1000 to 10000, preferably 2000 to 5000, and as long as it is within this range, it includes both branched and linear structures. But that's fine. There are no particular restrictions on the method for producing the polyester (A), and well-known and commonly used methods can be applied as they are, and the acid component and alcohol component are both well-known and commonly used dibasic acids, tribasic acids and more. Polybasic acids can be used, and dihydric alcohols and polyhydric alcohols of trihydric or higher hydric alcohols can be used. Therefore, to list only typical acid components and alcohol components, acid components include terephthalic acid, isophthalic acid, phthalic acid, methylterephthalic acid, trimellitic acid, pyromellitic acid, and their anhydrides. ;
or adipic acid, sebacic acid, succinic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyl-tetrahydrophthalic acid, hexahydrophthalic acid, methyl-hexahydrophthalic acid and their anhydrides; on the other hand, alcohol components Examples include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, bishydroxyethyl terephthalate, hydrogenated bisphenol A, and hydrogenated bisphenol A. Ethylene oxide adduct or propylene oxide adduct, trimethylolethane,
These include trimethylolpropane, glycerin, pentaerythritol, and 2,2,4-trimethylpentane-1,3-diol, and monoepoxy compounds can also be used as one of the glycol components. Next is the second component of the composition of the present invention. The above polymer (B) obtained in the presence of (β-methyl)glycidyl (meth)acrylate as an essential reaction component has a number average molecular weight of 300 to 5000, preferably 500 to 3000, particularly preferably 1000 to 2500. 20 to 100% by weight, preferably one or more (β-methyl)glycidyl (meth)acrylates selected from glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate and β-methylglycidyl methacrylate. 40 to 80% by weight, and 0 to 80% by weight of other vinyl monomers, preferably 20 to 60% by weight, particularly preferably 40 to 65% by weight. If the molecular weight of such a polymer is lower than 300, the mechanical strength of the resulting coating film will be insufficient, and smoke will be emitted when the coating film is baked; In either case, it is unsuitable because not only will the film quality or smoothness be poor, but the compatibility between the resins will also be poor, and the crosslinking reaction will not proceed sufficiently, resulting in poor coating film strength. be. In addition, if the amount of (β-methyl)glycidyl (meth)acrylate is less than 20% by weight,
Since the compatibility with the polyester (A) deteriorates and the reaction with the polyester (A) becomes insufficient, a good cured coating film cannot be obtained. Such (β-methyl)glycidyl (meth)acrylates include glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate, and β-methylglycidyl methacrylate, and among them, β-methylglycidyl methacrylate alone or in combination with glycidyl methacrylate. It is preferable to use it in combination with For this (β-methyl)glycidyl (meth)acrylate, vinyl monomers that may be used as copolymerization components include styrene,
Typical examples include (meth)acrylic acid ester, fumaric acid diester, acrylonitrile, acrylamide, etc. Among these (meth)acrylic acid esters, methyl methacrylate and cellosolve methacrylate are particularly suitable for polyester (A).
Both monomers account for 50% by weight or more of the copolymerization component,
In particular, it is preferable to use it in an amount of 70% by weight or more. It goes without saying that in addition to this, any material can be used as long as it can be copolymerized with the glycidyl (meth)acrylate. There are no particular restrictions on the method for producing the polymer (B), and well-known and commonly used methods can be applied as is, but advantages such as the ability to adjust or control the molecular weight by removing the solvent after the polymerization reaction can be expected. Among these, this solution polymerization method is recommended. The carboxyl group-containing vinyl polymer (C), which is the third component of the composition of the present invention, has an acid value of 10.
~200mgKOH/g, preferably 15-150mgKOH/g
and has a number average molecular weight of 300 to 10,000, preferably 2,000 to 5,000, and is obtained by copolymerizing a carboxyl group-containing monomer as described below with another vinyl monomer. Typical carboxyl group-containing monomers include acrylic acid, methacrylic acid, (anhydrous) maleic acid, fumaric acid, and itaconic acid. Typical examples include acrylic acid alkyl ester, methacrylic ester, styrene, vinyltoluene, acrylamide, and acrylonitrile. The resin composition of the present invention comprises the aforementioned polyester (A), polymer (B), and carboxyl group-containing vinyl polymer (C), and the usage ratio of each of these components is 60 to 60. 96 copies, 3-40 copies, and 1-20
parts, preferably 60-85 parts and 10-30 parts and 3 parts
The proportion is ~15 copies. The composition of the invention thus obtained contains pigments or other fillers, flow modifiers such as 2-ethylhexyl acrylate polymers or silicone, and optionally various catalysts such as amines, imidazole or metal soaps, or other additives. etc., and then kneaded using an extruder or the like, and then pulverized to form a powder coating. As a powder coating method, known methods such as electrostatic coating or fluidized dip coating can be employed. Next, the present invention will be specifically explained with reference to Examples, where all parts are by weight. Synthesis Example 1 A mixture consisting of 2049 parts of neopentyl glycol, 1911 parts of dimethyl terephthalate, and 1.1 parts of zinc acetate was gradually heated to 210°C while removing the methanol produced from the system, and then 67 parts of adipic acid, terephthalate, and 67 parts of adipic acid were added. 1375 〃 of acid and 1.5 〃 of dimethyltin oxide were added, and the temperature was raised to 240°C over 10 hours. Thereafter, the temperature of the reaction product was lowered to 180°C, and 330 parts of trimellitic anhydride was added to obtain a polyester having an acid value of 35, a softening point of 126°C, and a number average molecular weight of 3000. Hereinafter, this will be abbreviated as "polyester (A-1)". Synthesis Example 2 A mixture consisting of 951 parts of neopentyl glycol, 566 parts of ethylene glycol, 1836 parts of dimethyl terephthalate, and 1.8 parts of zinc acetate was gradually heated to 210°C while removing the generated methanol from the system, and then isophthalate was obtained. 1570 parts of acid and 2 parts of dibutyltin oxide were added, and the temperature was raised to 240°C over 10 hours.
Further, the reaction was continued at the same temperature to achieve an acid value of 25 and a softening point of
A polyester having a temperature of 105°C and a number average molecular weight of 3700 was obtained. Hereinafter, this will be referred to as "polyester (A-
2)". Synthesis example 3 β-methylglycidyl methacrylate
A mixture of 10 parts of glycidyl methacrylate, 40 parts of methyl methacrylate, 1 part of t-butyl perbenzoate, and 0.5 parts of cumene hydroperoxide was added dropwise to 100 parts of xylene at 150°C under pressure and polymerized. Upon removal of , a polymer having a number average molecular weight of 1500 was obtained. Hereinafter, this will be abbreviated as "polymer (B-1)". Synthesis Example 4 A mixture of 20 parts of β-methylglycidyl methacrylate, 30 parts of glycidyl methacrylate, 50 parts of cellosolve methacrylate, and 2 parts of t-butyl perbenzoate was added dropwise to 100 parts of xylene at 155°C to polymerize, and then the xylene was removed. A polymer having a number average molecular weight of 1300 was obtained. Hereinafter, this will be abbreviated as "polymer (B-2)". Synthesis Example 5 A number average molecular weight of 1700 was obtained in the same manner as Synthesis Example 4, except that 15 parts of methacrylic acid, 60 parts of styrene, 25 parts of n-butyl acrylate, 1 part of t-butyl perbenzoate and 0.5 parts of cumene hydroperoxide were used. A polymer having an acid value of 95 was obtained. below,
This is abbreviated as "polymer (C-1)". Synthesis Example 6 A number average molecular weight of 2000 and a number average molecular weight of 2000 and A polymer having an acid value of 75 was obtained. below,
This is abbreviated as "polymer (C-2)." Example 1 Polyester (A-1) obtained in Synthesis Example 1
70 parts and 20 parts of the polymer (B-1) obtained in Synthesis Example 3
and 10 parts of the polymer (C-1) obtained in Synthesis Example 5, and further added 50 parts of titanium oxide and 1 part of "Acronal 4F" (flow regulator manufactured by BASF, West Germany).
After mixing, the mixture was kneaded using an extruder, cooled, and pulverized to obtain a powder coating. Next, this paint was applied to a mild steel plate and baked at 180°C for 20 minutes to obtain a paint film. Example 2 The amount of polyester (A-1) used was changed to 75 parts, and 20 parts of polymer (B-2) and polymer (C-1) were used instead of polymer (B-1). 5
A coating film was obtained in the same manner as in Example 1, except that the polymer (C-2) in Example 1 was used. Example 3 Polyester (A-2) obtained in Synthesis Example 2 70
20 parts of the polymer (B-1) obtained in Synthesis Example 3,
Example 1 except that 10 parts of the polymer (C-1) obtained in Synthesis Example 5, 1 part of carbon black, 10 parts of barium sulfate, and 1 part of "Acronal 4F" were added.
A coating film was obtained in the same manner as above. The performance of the coating films obtained in each example is summarized in Table 1, and all were excellent in appearance, mechanical strength, and weather resistance. 【table】

Claims (1)

[Claims] 1 (A) Acid value 20-200mgKOH/g, softening point 80-150
60 to 96 parts by weight of a polyester having a temperature of 1,000 to 10,000 °C and a number average molecular weight of 1,000 to 10,000; 3 to 40 parts by weight of a glycidyl group-containing acrylic polymer having a number average molecular weight of 300 to 5,000 obtained from 1% by weight and 0 to 80% by weight of other vinyl monomers,
and (C) acid value 10-200mgHOH/g and number average molecular weight
1. A resin composition for powder coating, comprising 1 to 20 parts by weight of a vinyl polymer containing 300 to 10,000 carboxyl groups.