JPH0147502B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating resin composition that provides a coating film with excellent mechanical properties and weather resistance when cured at low temperatures. In recent years, as a room temperature drying paint with good weather resistance,
Acrylic lacquer and polyisocyanate-curing urethane paints are now widely used. However, although the former has the advantage of being low-priced, its physical properties are inferior to those of cross-linked paints, while the latter has superior coating properties, but is due to isocyanate-related problems. There are problems in terms of toxicity, price, etc., and neither of these can be said to be desirable. For this reason, research and development of new curing systems have been actively conducted, but at present no one with satisfactory performance has yet been obtained. In view of the current situation, the present inventors have conducted extensive research,
First, a polyepoxy compound is blended as a curing agent component into a resin component that is a mixture of a vinyl polymer having basic nitrogen in the side chain and a vinyl polymer having a carboxyl group in the side chain in a specific ratio. It was discovered that an inexpensive resin composition that provides a cured coating film with excellent curability and ultraviolet resistance could be obtained by this method, and a patent was filed (Japanese Patent Application No. 1983-21454). However, in such a composition, the viscosity of the paint increases due to the formation of a salt between the basic nitrogen and the carboxyl group, and as a result, the amount of non-volatile components must be reduced during painting, and the sharpness of the paint film is poor. There was a drawback. Therefore, as a result of repeated research in order to improve this drawback, the present inventors found that the above composition has three
It has been discovered that by adding a certain amount of a class amine compound, it is possible to significantly improve the non-volatile content of the paint without deteriorating the curability or physical properties of the paint film, and a paint film with excellent image clarity can be obtained.The present invention I was able to complete it. That is, the present invention provides (A) a vinyl polymer having a carboxyl group in its side chain, (B) a vinyl polymer having a basic nitrogen in its side chain, (C) a polyepoxy compound, and (D) a tertiary amine. A composition comprising a compound comprising at least 5% of the carboxyl groups of component (A).
Provided is a low-temperature curing resin composition for a paint, which is characterized by containing a component (D) that neutralizes the composition. Here, the above-mentioned vinyl polymer (A) having a carboxyl group in its side chain is obtained by copolymerizing a vinyl monomer having a carboxyl group with a vinyl polymer copolymerizable therewith. Of these, typical vinyl monomers with carboxyl groups include acrylic acid, methacrylic acid, crotonic acid, itaconic acid,
Fumaric acid or maleic acid, or adducts of vinyl monomers having a hydroxyl group and carboxylic acid anhydrides, and monoesters of dibasic acids such as itaconic acid, fumaric acid or maleic acid; Typical examples of vinyl monopolymers that can be copolymerized with are methacrylic esters such as methyl methacrylate, ethyl methacrylate or butyl methacrylate, acrylic esters such as methyl acrylate, ethyl acrylate or butyl acrylate, acrylic acid or Hydroxyalkyl esters of methacrylic acid or dialkyl esters of itaconic acid, fumaric acid or maleic acid, as well as vinyl acetate, styrene, α-methylstyrene,
Vinyltoluene, acrylonitrile, methacrinitrile, acrylamide, methacrylamide, 2
- Monomers containing phosphate groups such as methacryloxyethyl phosphate. The amount of the monomer having a carboxyl group is preferably 3 to 30% by weight from the viewpoint of curability and water resistance, and the amount of the other copolymerizable monomer is 97 to 70% by weight. be. Next, the above-mentioned vinyl polymer (B) having basic nitrogen in the side chain is obtained by copolymerizing a vinyl monomer having basic nitrogen with a vinyl monomer copolymerizable therewith. Among these, typical vinyl monomers having basic nitrogen include N,N-dimethylaminoethyl acrylate or methacrylate,
N,N-diethylaminoethyl acrylate or methacrylate, N-t-butylaminoethyl acrylate or methacrylate, allylamine, 2-vinylpyridine or 4-vinylpyridine, etc.; on the other hand, vinyl polymers copolymerizable with these include As typical examples, those mentioned above can be used as they are. The amount of the basic nitrogen-containing monomer to be used is not particularly limited, but is preferably in the range of 3 to 60% by weight from the viewpoint of curability and ultraviolet resistance. may range from 97 to 40% by weight. Although the vinyl polymers (A) and (B) described above can be prepared by any known method, solution radical polymerization is particularly preferred. In this case, the solvent may be an aromatic hydrocarbon such as toluene or xylene, an alcohol such as n-butanol, isobutanol or isopropanol, an ester such as ethyl acetate or butyl acetate, or a ketone such as methyl isobutyl ketone or acetone. Polymerization can be carried out by a conventional method using such a solvent and an azo or peroxide polymerization initiator. In addition, during polymerization, lauryl mercaptan,
Chain transfer agents such as 2-mercaptoethanol, 3-mercaptopropionic acid, and α-methylstyrene dimer can also be used. The mixing ratio (weight ratio) of the vinyl polymer (A) having a carboxyl group and the vinyl polymer (B) having a basic nitrogen group is determined from the viewpoint of curability, ultraviolet resistance, water resistance, etc. A):(B)=5-95:95-5, more preferably 10-90:90-10, and these
The content of basic nitrogen in the solid resin composed of the mixture of both vinyl polymers (A) and (B) is 0.1 to 1 equivalent/
1000g resin solids, particularly preferably within the range of 0.2 to 0.7 equivalent/1000g resin solids. Furthermore, the polyepoxy compound (C) as a curing agent component refers to a compound having at least two epoxy groups in one molecule, and a typical example thereof is ethylene glycol diglycidyl ether. , hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerin diglycidyl ether, glycerin polyglycidyl ether, diglycerin, polyglycidyl ether, sorbitol polyglycidyl ether, hydrogenated bisphenol-A di Polyglycidyl ethers of polyhydric alcohols such as glycidyl ether or bisphenol-A diglycidyl ether, or glycidyl ethers of p-oxybenzoic acid, phthalic acid diglycidyl esters or hexahydrophthalic acid diglycidyl esters, and also hydantoin rings. Examples include epoxy resins containing epoxy resins, and vinyl polymers having epoxy groups in side chains. The blending amount of the polyepoxy compound (C) is the number of equivalents of carboxyl groups in the polymer (A)/+polymer (A)
Number of equivalents of carboxyl group* *+ Number of equivalents of basic nitrogen of polymer (B)/component (C)
It may be selected such that the number of equivalents of epoxy groups in is in the range of 0.5 to 2. The tertiary amine compound (D) is a low-molecular compound containing one or more, preferably one to two, tertiary amino groups in one molecule, and representative examples include trimethylamine, triethylamine,
Tributylamine, N-methylmorpholine, N-
Ethylmorpholine, N,N-dimethylbenzylamine, N,N-dimethylaniline, N,N-dimethylaminoethanol, N,N-diethylaminoethanol, N,N-diisopropylaminoethanol, N,N-dibutylaminoethanol, 1
-dimethylamino-2-propanol, N,N,
N', N'-tetramethylethylenediamine, N,
Examples include N,N',N'-tetramethylhexamethylenediamine and N,N,N',N'-tetramethylpropylenediamine. Component (D) may be added in an amount equivalent to neutralizing at least 5% of the carboxyl groups in component (A), more preferably in an amount equivalent to 20 to 200%. And (D) component is (A) or (B) or (A) and (B) in advance.
It may be added to a mixture of components (A), (B), and (C). Various conventional methods can be used to prepare a coating material using the composition of the present invention. Depending on the situation, there is a method of preparing a composition by blending pigments, solvents, additives, etc., and then blending it with a polyepoxy compound (C) as a curing agent component immediately before use to form a paint. Fiber derivatives such as nitrocellulose and cellulose acetate butyrate may also be incorporated as additives in the preparation of paints from the composition of the present invention. The paint obtained in this way is applied to the object to be coated and kept at room temperature for about 1 to 2 days, or if necessary for 60 to 60 days.
It is sufficiently cured by drying at 80°C for 20 to 30 minutes, and a cured coating film having mechanical strength and ultraviolet resistance comparable to that of urethane paints can be obtained. Moreover, the paints obtained from the compositions of the present invention are significantly cheaper than urethane paints, and there are no concerns about toxicity, which is often a problem with urethane paints. Therefore, the composition of the present invention can be effectively used in various applications conventionally used in urethane paints, such as automobile repair, woodworking, building materials, and plastics. Next, the present invention will be specifically explained using examples.
Hereinafter, all parts and percentages are based on weight. Preparation Example 1 Toluene was added to 3 flasks equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and condenser.
300 parts and 300 parts of n-butanol were charged, and the temperature was raised to 110°C under a nitrogen stream. Next, at the same temperature, 300 parts of styrene, 297 parts of methyl methacrylate, and 150 parts of butyl methacrylate were added.
parts, butyl acrylate 150 parts, acrylic acid 103 parts
parts, 10 parts of azobisisobutyronitrile, 5 parts of t-butylperoxybenzoate and toluene.
A mixture of 400 parts was added dropwise over a period of 4 hours and then kept at the same temperature for 10 hours to reduce the non-volatile content to 53.3%.
A carboxyl group-containing polymer solution A-1 having a Gardner viscosity of X, a Gardner color of 1 or less, and an acid value of 38.1 was obtained. Preparation Example 2 Into the same reactor as Preparation Example 1, add 300 parts of toluene, n
- Add 300 parts of butanol and heat to 110℃ under nitrogen stream.
The temperature rises to Next, from 300 parts of styrene, 338 parts of methyl methacrylate, 150 parts of butyl methacrylate, 150 parts of butyl acrylate, 62 parts of methacrylic acid, 15 parts of azobisisobutyronitrile, 3 parts of t-butylperoxybenzoate and 400 parts of toluene. The mixture was added dropwise over a period of 4 hours, and then maintained at the same temperature for 10 hours to obtain a carboxyl group-containing polymer solution A-2 having a nonvolatile content of 51.9%, a Gardner viscosity T, a Gardner color of 1 or less, and an acid value of 19.7. Obtained. Preparation Example 3 300 parts of toluene and 300 parts of n-butanol were placed in the same reactor as in Example 1, and the mixture was heated to 80 parts under a nitrogen stream.
The temperature was raised to ℃. Next, a mixture consisting of 300 parts of styrene, 300 parts of methyl methacrylate, 200 parts of butyl acrylate, 200 parts of dimethylaminoethyl methacrylate, 20 parts of azobisisobutyronitrile and 400 parts of toluene was added dropwise over a period of 4 hours. Then,
By maintaining the same temperature for 10 hours, a polymer solution B-1 having basic nitrogen having a nonvolatile content of 51.4%, a Gardner viscosity of S, and a Gardner color of 1 to 2 was obtained. Preparation Example 4 The same operation as Preparation Example 3 was repeated except that butyl acrylate was replaced with 300 parts of butyl methacrylate and dimethylaminoethyl methacrylate was changed to 100 parts. A polymer solution B-2 having a basic nitrogen content of 1 or less was obtained. Examples 1 to 3 and Comparative Examples 1 to 3 Clear paints were prepared according to the formulations listed in Table 1, and toluene/n-butanol = 70/3
diluted with 0 mixed solvent and applied to zinc phosphate treated steel plate.
It was applied to a film thickness of 50μ. Then at 60℃
After being force-dried for 30 minutes and left at room temperature for 1 day, the film performance was evaluated. As shown in Table 1, the nonvolatile content of the paint prepared from the composition of the present invention during application is significantly higher than that of the comparative example, and the amount of solvent can be reduced accordingly.
The coating film had good image clarity and physical properties. Here, the UV resistance was determined by applying the above clear paint on a pre-applied white urethane film in the same manner as above, and then applying it at 23℃ for 1 hour.
After drying for a week, apply a 15W germicidal lamp from a distance of 20cm.
Evaluation was made by examining the change in yellowing degree of the coating film irradiated for 24 hours (specifically, the Δb value - the difference between the b value of the unirradiated coating film and that of the irradiated coating film). This△
The smaller the b value, the better the UV resistance.

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Claims (1)

[Scope of Claims] 1 (A) Copolymerization of 3 to 30% by weight of a monomer having a carboxyl group and 97 to 70% by weight of a monomer copolymerizable with this carboxyl group-containing monomer. 5 to 95 parts by weight of the vinyl polymer having a carboxyl group in the side chain obtained by 97-40% by weight of other monomers copolymerizable with the amount
95 to 5 parts by weight of a vinyl polymer having a basic nitrogen atom in the side chain obtained by copolymerizing (C)
A composition comprising a polyepoxy compound and (D) a tertiary amine compound, the number of equivalents of carboxyl groups of the above polymer (A) + the above polymer (
Contains the compound (C) within the range such that the number of equivalents of basic nitrogen in B)/the number of equivalents of the epoxy group in the above compound (C) = 0.5 to 2, and the number of equivalents of the carboxyl group in the polymer (A). A resin composition for a low-temperature curing coating, characterized in that it contains the above compound (D) in an amount equivalent to neutralizing at least 5%.