JPH0211609B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin composition for coatings that can be baked at low temperatures, has fast curing properties, and can form a cured coating film with excellent gloss, physical properties of the coating film, and solvent resistance. Ever since oil shocks, there has been a growing trend towards saving resources and energy, and the field of baking paints is no exception, with various measures being taken to save energy by lowering the temperature of baking furnaces. By the way, compounds with an allyl group in the side chain are
It is well known that they generally cure at room temperature and have the property of curing at low temperatures and in a short time by heating. Therefore, the present inventors focused on the unique properties of such allyl group-containing compounds and conducted intensive studies to obtain a paint resin that can be baked at low temperatures. When introducing the allyl group into a general-purpose vinyl polymer and blending an alkyl etherified aminoplast resin and/or a polyisocyanate compound as a curing agent component, these allyl groups, specific functional groups, and curing agent component The present inventors have now completed the present invention by discovering that a useful resin composition for coatings can be obtained that has low-temperature curing properties through a composite curing process between the two. That is, the present invention provides an allyl compound (a-1) having one or more functional groups selected from a hydroxyl group, a carboxyl group, and a glycidyl group, each having a hydroxyl value per solid content of 30 to 150, an acid value of 0.1 to 50, and a vinyl polymer (a-2) having an epoxy value of 0 to 100, which has an average of 2 to 20 allyl groups in one molecule, and has an epoxy value of 200 to 100.
Alkyl etherified aminoplast resin (b-1) and/or polyisocyanate compound (b-2) to 60 to 90 parts by weight of allyl group-containing vinyl polymer (A) having a number average molecular weight of 20,000.
[Hereinafter, these (b-1) and (b-2) may be collectively referred to as "curing agent component (B)." ] in a proportion of 40 to 10 parts by weight to provide a resin composition for paint. Here, the allyl group-containing vinyl polymer (A), which is the first component of the composition of the present invention, is generally prepared by reacting a vinyl polymer having a carboxyl group in the side chain with, for example, allyl glycidyl ether. However, as an alternative method, a carboxyl group-containing allyl compound such as a monoester of a dibasic acid such as succinic acid, maleic acid or fumaric acid with allyl alcohol or ethylene glycol monoallyl ether, and glycidyl Reaction with group-containing vinyl polymers, or ethylene glycol monoallyl ether, trimethylolpropane monomer,
Even if an allyl group is introduced into the side chain by reacting a diallyl ether compound or a mono-, di-, or triallyl ether compound of pentaerythritol, a hydroxyl group-containing vinyl polymer, and a diisocyanate compound such as hexamethylene diisocyanate. good. Furthermore, an allyl group may be introduced into the side chain by reacting an allyl compound containing a hydroxyl group or a methylol group with a vinyl polymer containing a carboxylic anhydride group. In this way, an allyl compound having an allyl group and one or more functional groups selected from a hydroxyl group, a carboxyl group, and a glycidyl group in one molecule, and a hydroxyl group that can be combined with the above functional group in the allyl compound, The polymer (A) can be obtained by reaction with a vinyl polymer having one or more functional groups selected from carboxyl groups, glycidyl groups, and carboxylic anhydride groups; The vinyl polymer (a-2) having one or more functional groups selected from carboxylic acid groups is copolymerizable with a polymer monomer containing any one of these functional groups. Obtained by copolymerizing with other monomers. Here, representative examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and N-methylolated monomers. (meth)acrylamide, or a monoester of polyhydric alcohol such as glycerin or trimethylolpropane with (meth)acrylic acid, and the above carboxyl group-containing or carboxylic anhydride group-containing monomer is (meth)acrylic acid. In addition to itaconic acid,
Monoesters of dibasic acids such as crotonic acid or maleic anhydride are typical examples, and glycidyl (meth)acrylate is a typical example of the glycidyl group-containing monomer. On the other hand, representative monomers that are copolymerizable with each of these monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylate. isobutyl acrylate,
These include 2-ethylhexyl (meth)acrylate, acrylonitrile, styrene, vinyltoluene, vinyl acetate, dibutyl fumarate or dibutyl itaconate, as well as oil-free alkyd resins with copolymerizable unsaturated double bonds. It will be done. The vinyl polymer (a-2) having a hydroxyl group, a carboxyl group, a glycidyl group, and/or a carboxylic anhydride group in its side chain is prepared by adding various monomers such as those mentioned above to benzoyl peroxide, kyumene hydroperoxide, etc. , di-tertiary butyl peroxide, di-tertiary butyl hydroperoxide, azobisisobutyronitrile or azobisisobutyramide. preferable. Solvents used in this solution polymerization include aromatic hydrocarbons such as benzene, toluene or xylene; ketones such as methyl ethyl ketone or methyl isobutyl ketone; esters such as ethyl acetate, butyl acetate or cellosolve acetate; butanol. or alcohols such as isobutanol; or cellosolves such as methyl cellosolve or butyl cellosolve are typical examples, and these may be used alone or in combination depending on the purpose. In this way, allyl compounds (a-
1) and the hydroxyl value is in the range of 30 to 150, preferably 40 to 100, the acid value is in the range of 0.1 to 50, preferably 5 to 25, and the epoxy value is in the range of 0 to 100, preferably 1). By reacting with a vinyl polymer (a-2) having a range of 0 to 50, a vinyl polymer (A) having an average of 2 to 20 allyl groups in one molecule is produced. can get. If the number of allyl groups is less than 2, the low-temperature curability will be poor, and if it exceeds 20, it will have an adverse effect on stability, which is not preferred. Allyl group-containing vinyl polymer thus obtained
The curing agent component (B) to be added to (A) includes an alkyl etherified aminoplast resin (b-1) and a polyisocyanate compound (b-2), of which the former resin (b-1) is representative. Examples include methylated melamine resins, butylated melamine resins, butylated urea resins or butylated benzoguanamine resins, while the latter compounds (b-
Typical examples of 2) include hexamethylene diisocyanate, tolylene diisocyanate, O-, m
- or diisocyanates such as p-xylene diisocyanate or diphenylmethane diisocyanate; or those obtained by adding these diisocyanates to the hydroxyl groups of polyhydric alcohols such as glycerin, trimethylolpropane, or pentaerythritol; There are polyisocyanate compounds such as those obtained by forming biuret bonds with a small amount of water. Furthermore, polyisocyanates in which the isocyanate groups in these addition polyisocyanate compounds are blocked with a known and commonly used blocking agent such as phenol, oxime or methanol can also be used. If necessary, an epoxy resin may be added to the composition of the present invention to further improve the corrosion resistance of the coating film. Generally, a diglycidyl ether type epoxy resin of bisphenol A is used. Typical examples include "Epicron 1050, 4050" (products of Dainippon Ink & Chemicals Co., Ltd.), "Epicote 828, 1001, 1004" (products of Ciel Chemical Co., Ltd.), or "Araldite 6071, 6084".
(Ciba Geigy product) etc. are commercially available. In such a case, the blending ratio (weight % ratio) of the allyl group-containing vinyl polymer and the epoxy resin as a curing agent component is suitably in the range of 50-95:5-40:0-20. In addition, when baking the composition of the present invention at a low temperature and in a short time, it is desirable to add a metal dryer, which can also be called an allyl group curing accelerator, and such metal dryers include magnesium, calcium, manganese, Examples include naphthenate or octanoate such as cobalt. The amount used is in the range of 0 to 1.0% by weight, more preferably 0.01 to 0.5% by weight of the metal content, based on the resin solid content. If it exceeds 1.0% by weight, stability decreases, which is not preferable. Furthermore, peroxides can also be used with this metal dryer, and typical examples of such peroxides include methyl ethyl ketone peroxide,
Examples include benzoyl peroxide, di-tertiary-butyl peroxide, tertiary-butyl hydroperoxide, cumene hydroperoxide or tertiary-butyl perbenzoate. The amount of peroxide to be used is 1% by weight or less, more preferably 0.01 to 0.5% by weight, based on the solid content of the resin. The thus obtained composition of the present invention has a fast curing property that allows a cured coating film to be obtained by baking at a low temperature and in a short time, but the physical properties of the coating film are extremely good, and the coating film has gloss, flexibility, and solvent resistance. It also has the advantage of being excellent in hardness, stain resistance, and chemical resistance, and has a wide range of uses as a top coat paint for automobiles, home appliances, etc. Next, the present invention will be specifically explained with reference to Examples, and unless otherwise specified, all parts and percentages are based on weight. Reference Example 1 [Allyl group-containing vinyl polymer (A-
Adjustment example of 1)] 150 parts of xylene and 60 parts of n-butanol were charged into a reactor equipped with a stirrer, a thermometer, a cooler, a dropping device, and a nitrogen gas inlet, and the temperature was raised to 110°C while blowing nitrogen gas. Heat styrene 150 at the same temperature.
After adding dropwise over 5 hours a mixture of monomers consisting of: The temperature was gradually raised to 120°C, and 120 parts of xylene was added dropwise over a further 2 hours. Then, the reaction was continued for about 10 hours, and the solid content was 51.2%, the viscosity (Gardner, hereinafter the same) was Y-Z ² , and the color number (Gardner, the same below).
is 1 and the acid value is 38.6 (a-
After obtaining 2-1), add α-methylstyrene to it.
18 parts, 0.6 parts of 2-methylimidazole, 45.6 parts of allyl glycidyl ether, and 45.6 parts of xylene were charged and reacted at 120°C for 3 hours. The solution of the allyl group-containing vinyl polymer (A-1) thus obtained had a solid content of 50.8% and a viscosity of
Y, acid value was 7.5, and color number was 1-2. Reference Example 2 [Preparation Example of Comparative Control Polymer (A'-1)] 150 parts of xylene and 60 parts of n-butanol were charged into the same reactor as in Reference Example 1, and the temperature was raised to 110°C while blowing nitrogen gas. At the same temperature, styrene 172.8
parts, 54 parts of 2-hydroxylethyl methacrylate,
125.7 parts of butyl acrylate, 7.5 parts of acrylic acid, 30 parts of xylene and azobisisobutyronitrile
A mixture consisting of 3.6 parts was added dropwise over a period of 5 hours,
Next, after raising the temperature to 120°C, 120 parts of xylene was added dropwise over 2 hours, and the reaction was continued for about 10 hours. The solution of polymer (A'-1) thus obtained had a solid content of 49.9%, a viscosity of W ² -X, an acid value of 7.7, and a color number of 1. Reference Example 3 [Preparation Example of Comparative Control Polymer (A'-2)] A vinyl polymer (a-2-1) was obtained by carrying out the same operation as in Reference Example 1, but the following allyl glycidyl ether, etc. A polymer obtained without any charging and therefore without any allyl group introduction reaction was designated as a comparative polymer (A'-2). Reference Example 4 [Allyl group-containing vinyl polymer (A-
Preparation example of 2)] 210 parts of xylene was charged into the same reactor as in Reference Example 1, and the temperature was raised to 110°C while blowing nitrogen gas, and at the same temperature, 108 parts of styrene and 2-methacrylic acid were added.
54 parts of hydroxyethyl, 162 parts of ethyl acrylate,
A mixture of monomers consisting of 36 parts of methacrylic acid, 30 parts of xylene, and 3.6 parts of azobisisobutyronitrile was added dropwise over a period of 5 hours, and then the temperature was gradually raised to 120°C for an additional 2 hours. of xylene was added dropwise, and the reaction was continued for about 10 hours to obtain a vinyl polymer (a-2-2). Thereafter, 4.2 parts of dipentene, 0.6 parts of 2-methylimidazole, 35.0 parts of allyl glycidyl ether, and xylene were added to this polymer (a-2-2).
35.8 parts were charged and reacted at 120°C for 3 hours. The solution of the allyl group-containing vinyl polymer (A-2) thus obtained had a solid content of 51.7%, a viscosity of W-X,
It had an acid value of 8.2 and a color number of 1. Reference Example 5 [Example of Preparation of Comparative Control Polymer (A'-3)] The same operation as in Reference Example 4 was carried out except that 118 parts of styrene, 177.2 parts of ethyl acrylate, and 10.8 parts of methacrylic acid were used. The process was repeated to obtain a vinyl polymer (a-2-3). The same procedure as in Reference Example 4 was repeated except that this polymer (a-2-3) was used, and the amounts of allyl glycidyl ether and xylene to be charged therein were changed to 4.8 parts. , an ^allyl group-containing vinyl polymer (A' -3) was obtained. Reference Example 6 [Allyl group-containing vinyl polymer (A-
3) Preparation example] In a reaction vessel similar to Reference Example 1, add 310 xylene
The temperature was raised to 110℃ in a nitrogen gas stream,
At the same temperature, 58 parts of styrene, 50 parts of methyl methacrylate, 144 parts of n-butyl methacrylate, 20 parts of isobutyl acrylate, 2-
80 parts of ethylhexyl, 8 parts of maleic anhydride,
A mixture consisting of 5 parts of xylene and 5 parts of azobisisobutyronitrile was added dropwise over 5 hours, and the reaction was continued by maintaining the same temperature for about 15 hours to produce a vinyl polymer. (a-
2-4) was obtained. Next, the temperature was raised to 120°C, and this polymer (a-
2-4) was charged with 6 parts of "Dipentene-T" (Dipentene manufactured by Nippon Terpene Chemical Co., Ltd.), 10.7 parts of glycerin monoallyl ether, 10.7 parts of xylene, and 0.1 part of 2-methylimidazole. 120
When the reaction was carried out by keeping it at ℃ for 3 hours,
The solid content is 50.5%, the viscosity is V, the acid value is 6.0, and
A desired polymer having a color number of 1 was obtained. Hereinafter, this will be abbreviated as polymer (A-3). Example 1 The polymer (A-1) obtained in Reference Example 1, "Supervecamine L-121-60" (butylated melamine resin manufactured by Dainippon Ink and Chemicals Co., Ltd.), "Epiclon
1050” and “Typeke R-580” (Ishihara Sangyo)
(rutile type titanium oxide) manufactured by Co., Ltd.) at a solid content weight ratio of 65:
Mix it so that it is 30:5:100, knead it in a ball mill, and then mix it with a mixed solvent of xylene:n-butanol=70:30 (weight ratio) for 20 seconds (Food Cup #4). The dilution was adjusted as follows. Thereafter, 24% lead naphthenate and 6% cobalt naphthenate were added in an amount corresponding to 0.5% each based on the resin solid content of the prepared paint. Comparative Examples 1 and 2 In place of polymer (A-1), Reference Example 2 was used, respectively.
Two types of paints were obtained by repeating the same operation as in Example 1, except that polymers (A'-1) and (A'-2) obtained in Example 1 and 3 were used separately. Example 2 A coating material was obtained in the same manner as in Example 1, except that the polymer (A-2) obtained in Reference Example 4 was used instead. Comparative Example 3 A coating material was obtained in the same manner as in Example 1, except that the polymer (A'-3) obtained in Reference Example 5 was used instead. Example 3 The polymer (A-2) obtained in Reference Example 4 and "Tiepeke R-580" were combined to achieve PWC50 in the final blend.
% in a ball mill, and then mixed with "Bernok DN-950" (Dainippon Ink & Chemicals Co., Ltd.).
Isocyanate prepolymer) -OH/-
After blending so that NCO=1/1, the mixture was diluted for 20 seconds (food cup #4) with a mixed solvent of xylene:butyl acetate=50:50 (weight ratio). Thereafter, 0.6 parts and 0.2 parts of 24% lead naphthenate and 6% cobalt naphthenate were added to this prepared paint, respectively, based on the solid content of the polymer (A-2) used therein. Barnotsk
Only DN-950 was added just before painting. Comparative Example 4 A coating was prepared in the same manner as in Example 3, except that the polymer (A'-3) obtained in Reference Example 5 was used. Example 4 The blending ratio of the polymer (A-3) obtained in Reference Example 6, "Super Betsukamine L-121-60" and "Tiepeque R-580" was determined by solid content weight ratio.
A paint was obtained in the same manner as in Example 1, except that the composition was changed to 48:12:40. Example 5 The polymer (A-1) obtained in Reference Example 1, "Supervecamine L-121-60", and "Burnok D-550" [block type manufactured by Dainippon Ink and Chemicals Co., Ltd.] Example 1 was carried out in the same manner as in Example 1, except that the blending ratio of [Isocyanate prepolymer] and "Tiepeque R-580" was changed to a blending composition such that the solid content weight ratio was 70:20:10:100. I got the paint. The various paints obtained above were applied to steel plates separately, and the paints obtained in Examples 1, 2, 4 and 5 and Comparative Examples 1, 2 and 3 were coated with
On the other hand, in the case of the coatings obtained in Example 3 and Comparative Example 4, the coating performance after baking at 80℃ for 20 minutes was evaluated. It is shown in Table-1.

【table】

【table】

Claims (1)

[Claims] 1 Allyl compound (a-1) having one or more functional groups selected from hydroxyl group, carboxyl group, and glycidyl group, and each having a hydroxyl value per solid content of 30 to 150, an acid value of 0.1 to 50, and an epoxy value is a vinyl polymer in the range of 0 to 100 (a-
2) on average 2 to 1 molecule in one molecule obtained by reacting with
An allyl group-containing vinyl polymer (A) having 20 allyl groups and a number average molecular weight of 2,000 to 20,000.
A resin composition for coating, comprising 40 to 10 parts by weight of an alkyl etherified aminoplast resin (b-1) and/or a polyisocyanate compound (b-2) to 60 to 90 parts by weight.