JPH02115283A - Resin composition for automotive repair coating material - Google Patents

Abstract

PURPOSE:To obtain the title composition improved in low-temperature curability and properties of a cured film by mixing two specified polymers together. CONSTITUTION:A polymer (A) is obtained by copolymerizing 1-20wt.% polymerizable unsaturated carboxylic monomer (e.g., methacrylic acid) with 80-99wt.% another polymerizable unsaturated monomer, desirably a mixture of cyclohexyl methacrylate with methyl methacrylate, t-butyl methacrylate and lauryl methacrylate. Separately, another polymer (B) is obtained by (co) polymerizing 5-100wt.% addition-polymerizable oxazoline (e.g., 2-isopropenyl-2- oxazoline) with, optionally, other polymerizable unsaturated monomers. Component A is mixed with component B in such an amount that 0.1-3.0 equivalents of the oxazoline groups of component B are present per equivalent of the carboxyl groups of component A.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a resin composition for automobile refinish paints, and more specifically, it exhibits excellent curing properties under low temperature curing conditions and also has excellent coating film performance after curing. The present invention relates to a resin composition for automotive refinish paint.

Problems to be Solved by the Prior Art and the Invention> The field of automotive refinish paints is a field that does not inherently require heat treatment, and conventionally, acrylic lacquers that dry at room temperature and acrylic lacquers that dry at room temperature with added nitrocellulose, cellulose acetate butyrate, etc. Two-component urethane resin paints are widely used. The former acrylic lacquer is inexpensive and easy to use, and the two-component urethane resin paint has excellent coating performance due to the crosslinking reaction between polyol and polyisocyanate. It has the following drawbacks. In other words, in order to obtain the desired performance of acrylic lacquer, it is necessary to increase the molecular weight of the polymer or raise the glass transition temperature, and in order to ensure workability, it is necessary to dilute it with a large amount of organic solvent. . This does not meet the recent demand for high-solid paints from the viewpoint of resource conservation, environmental pollution, etc. Furthermore, two-component urethane resin paints have a problem with toxicity due to the polyisocyanate used.

Although various research and development efforts have been made to develop new curing systems to solve these problems, the current state of the art is that no automotive refinishing paint with performance comparable to conventional techniques has been obtained.

Means and operation for solving the above problems> The present inventors, with respect to the current situation, have developed a coating material for automobiles that exhibits excellent curing properties even at low temperatures and whose cured coating film has excellent performance. As a result of intensive research to develop a resin composition, an 8il resin composition for automobile refinish paints containing a polymer having a carboxyl group (A) and a polymer having an oxazoone group (B) as essential components has achieved the above purpose. We have discovered what can be achieved and completed the present invention.

That is, the present invention provides (a) a polymerizable unsaturated monomer containing a carboxyl group (
a) (hereinafter referred to as monomer (a)) 1 to 20% by weight and other polymerizable unsaturated monomers (b) (hereinafter referred to as monomer (
b)) 80-99% by weight (however, (a) + (
b) is 100% by weight)
Polymer (A) obtained by copolymerizing and (a) general formula (I) R2R) (wherein R1, R2, R3, R- each independently represents hydrogen, halogen, alkyl, aralkyl, phenyl or addition-polymerizable oxazoline (C) (hereinafter referred to as monomer (C)) represented by a phenyl group, and R5 is an acyclic organic group having an addition-polymerizable unsaturated bond;
A polymer (B) obtained by (co)polymerizing a monomer component (2) consisting of other polymerizable unsaturated monomers (d) (hereinafter referred to as monomer (d)) as necessary. The present invention relates to a resin composition for automobile refinish paint, characterized by containing the following.

Examples of the monomer (a) used in the production of the polymer (A) include unsaturated monocarboxylic acids such as (meth)acrylic acid, cinnamic acid and crotonic acid; maleic acid, maleic anhydride, itaconic acid, Examples include unsaturated dicarboxylic acids such as fumaric acid and monoesters thereof, and one or more selected from these groups can be used. The monomer (a) is a component for imparting reactivity to the polymer (B) to the polymer (A), and is used in an amount of 1 to 20% by weight based on the monomer component (1). If the amount used is less than 1% by weight, it may become an effective amount for the reaction with polymer (B), whereas if it exceeds 20% by weight, the water resistance of the cured coating film will decrease, which is not preferable.

The monomer (b) used in the production of the polymer (A) is not particularly limited as long as it is copolymerizable with the monomer (a) and does not have an oxazoline group. For example, methyl (meth) ) acrylate, ethyl (meth)acrylate,
Propyl (meth)acrylate, isopropyl (meth)
Acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)
Acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate,
(meth)acrylic alkyl esters such as lauryl (meth)acrylate and stearyl (meth)acrylate;
(Meth) such as cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, etc.
Acrylic acid cycloalkyl ester; Others (meth)acrylamide, N-methylol (meth)acrylamide, (meth)acrylonitrile, N,N'-dimethylaminoethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxy Propyl (meth)acrylate, styrene, α-methylstyrene, vinyltoluene, vinyl acetate, vinylpyridine, vinylimidazole, etc. can be mentioned, and one or two of these can be used.
More than one species can be used.

Monomer (b) accounts for 80 to 99% by weight in monomer component (1).
Use within the range. If the amount of the monomer (b) used is less than 80% by weight, the amount of the monomer (a) increases, resulting in a decrease in water resistance, and if it exceeds 99% by weight, the amount of the component (a) increases.
The amount of a) used becomes less than the amount specified in the present invention,
The features of the present invention will no longer be exhibited. Among the above monomers (b), cyclohexyl methacrylate, methyl methacrylate, tert-butyl methacrylate, and lauryl methacrylate are monomers that can be preferably used in the present invention, and when used in combination, It exhibits a remarkable synergistic effect in obtaining a P4 resin composition for automobile refinish paints with excellent image quality and image clarity. Furthermore, cyclohexyl methacrylate.

Methyl methacrylate, tert-butyl methacrylate, lauryl methacrylate in an amount of 2 to 50% by weight based on the total amount of monomer (a) and monomer (b)15 to
50% by weight 15-30% by weight 15-30% by weight (however,
The total amount of these monomers is monomer (a) and monomer (b).
) for the total amount of 17-99f! The amount is %. ), the above performance is further improved.

The monomer (C) used in the production of the polymer (B) used in the present invention has the general formula CI) R2R3 Rs (wherein R+, R2, Rt, and R- each independently represent hydrogen, halogen, , alkyl, aralkyl, phenyl or substituted phenyl, and Rs is an acyclic organic group having an addition-polymerizable unsaturated bond). Specific examples include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-
Vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-
Methyl-2-oxacillin, 2-impropenyl-5-
Examples include ethyl-2-oxacillin, and one type or a mixture of two or more types selected from these groups can be used. Among them, 2-isopropenyl-2-
Oxazo-non is preferred because it is industrially available.

When producing polymer CB), monomer (
d) may be used as a copolymerization component of monomer (e),
Monomer (d) can be used without any particular restriction as long as it is copolymerizable with monomer (C) and does not have a carboxyl group in its molecule. For example, diary polymer (A
Examples of the monomer (b) used in the production of ) are listed, and one or more of them can be used.

The amount of monomer (C) used is not particularly limited, but it is preferably 5 to 100% by weight in monomer component (2). ) may impair the durability of the cured coating, which can be a substantially effective amount. In particular, the polymer (A) is cyclohexyl methacrylate, methyl methacrylate,
When obtained using tertiary-butyl methacrylate and lauryl methacrylate, it is preferable that the amount of polymer (B) used is as small as possible in order to more fully express its characteristics; in this case, the monomer <C> is It is more preferable to use a larger amount within the above range.

Polymer (A), which is an essential component of the resin composition for automobile refinish paint of the present invention, contains monomer (a) and monomer (b), and polymer CB) contains monomer (C) and optionally Monomer (
d) are obtained by (co)polymerizing each of them. Polymerization can be carried out by well-known methods, for example Solu 7F! Polymerization method, suspension polymerization method, bulk polymerization method.

Examples of emulsion polymerization methods include solution polymerization methods, but in order to maximize the characteristics of the present invention, solution polymerization methods are preferable. When employing solution polymerization methods, azobisisobutyronitrile, benzoyl peroxide, etc. are used as polymerization initiators. Radical polymerization initiators such as oxide and di-tert-butyl peroxide can be used, and as polymerization solvents, toluene, xylene and other high boiling point aromatic solvents such as ethyl acetate, butyl acetate and cellosolve can be used. Ester solvents such as acetate-1; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; alcohol solvents such as methyl alcohol, ethyl alcohol, inglobil alcohol, and butyl alcohol can be used alone or in combination.

The resin composition for automobile refinish paint of the present invention contains the polymer (A) and polymer (B) obtained by the above procedure. ii The ratio of polymer A) and polymer (B) is not particularly limited and can be set within a wide range, but it is necessary to achieve necessary and sufficient performance such as dryness, hardness, weather resistance, water resistance, and solvent resistance. The amount of oxazoline groups is 0.1 to 3.0 per equivalent of carboxyl group contained in the polymer (A).
It is preferably in the range of 0 equivalent, more preferably 0.
It is in the range of 3 to 2.0 equivalents. When the resin composition for automobile refinish paint of the present invention is used, the polymer (A) and the polymer (B) are mixed into one liquid. However, there is no particular restriction on the mixing method, and there is no particular restriction on the mixing method. It can be done depending on the method. Furthermore, at this time, coloring H14, body pigments, curing catalysts, and other commonly used additives and fillers can also be blended.

<Effects of the Invention> The resin composition for automotive refinish paint of the present invention exhibits excellent curing characteristics under low temperature curing conditions. Therefore, after low-temperature baking, the coating is so excellent that it can be used for automotive repair work such as installing automotive parts immediately! Indicating the rise in I hardness and the tightening of the coating film,
Furthermore, the coating film properties such as hardness, weather resistance, water resistance, and solvent resistance after complete curing are excellent, and it can be effectively used as an automobile repair paint.

<Examples> The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

In the examples, unless otherwise specified, % means % by weight, and parts means parts by weight.

Reference Example 1 One part of isopropyl alcohol is placed in a four-bottle flask equipped with a stirrer, a boiler, a condenser, a dropping funnel, and a nitrogen gas inlet tube.
00 parts were charged and the temperature was raised to 80°C.

12 parts of methacrylic acid while blowing nitrogen gas into it,
20 parts of methyl methacrylate, 15 parts of cyclohexyl methacrylate, 18 parts of tert-butyl methacrylate, 20 parts of butyl acrylate.

A mixture consisting of 15 parts of lauryl methacrylate and 1.0 part of azobisisobutyronitrile was added dropwise from the dropping funnel over a period of 2 hours, kept at 80°C for 6 hours, and then cooled to room temperature to obtain a mixture containing carboxyl groups. A solution of polymer (A-1) was obtained.

Reference examples 2 to 4. Comparative Reference Examples 1 to 2 Polymers (A-2) to (A- 4) and comparative polymer (A'-1
) to (A'-2) solutions were obtained.

Table 1 Reference Example 5 100 parts of ethyl acetate was placed in a four-bottle flask similar to Reference Example 1, and the temperature was raised to 80°C. While blowing nitrogen gas there, 2-impropenyl-2-oxaf 922
5 parts, 40 parts of methyl methacrylate.

20 parts of cyclohexyl methacrylate, tertiary
A mixture consisting of 15 parts of butyl methacrylate and 1.5 parts of azobisisobutyronitrile was added dropwise from the dropping funnel over 2 hours, and the mixture was further maintained at 80°C for 6 hours, cooled to room temperature, and then a polymer containing an oxazoline group was added. Combine (
A solution of B-1) was obtained.

Reference Examples 6 to 8 Polymers (E-2) to (B-4) were prepared by repeating the same operations as in Reference Example 5, except that the composition of the polymerizable monomer was as shown in Table 2. ) was obtained.

2nd ft Examples 1-7. Comparative Examples 1 to 3 Polymer (A) 9 Polymer (B
) to prepare resin compositions (1) to (7) for automobile refinish paints.
) and comparative automotive supplementary paint resin compositions (1') to (3
′) was obtained. After coating these resin compositions for automobile refinishing paints on a mild steel plate to a dry film thickness of 40μ,
Force drying was performed at °C for 40 minutes. The drying properties and coating layer performance test results of these resin compositions for automobile refinish paints are shown in Table 3. The performance test method and its evaluation criteria are as follows.

1) Drying property: Evaluated by finger touch on forced drying.

0... No change O... A little mark left
``A Surface condition after rubbing with cotton 50 times.

O... No abnormality 0... Loss of gloss ×... Paint film melted and disappeared 3) Humidity resistance: Surface condition R after being left in an atmosphere of 50°C and 198% RH for 4 days.

■ ... No abnormality 0 ... Slight matting × ... Significant matting, blistering 4) Gasoline resistance = Surface condition after soaking for 2 hours.

O... No abnormality O... Slightly dulling × ... Significantly dulling 5) Cycle test: (18 hours of germicidal lamp irradiation) + (2 hours of water immersion) + (-20
One cycle is (°C, 2 hours) + (60°C, 2 hours), and the surface condition of the coating film after 1O cycle.

■ ... No abnormality 0 ... Slight loss of gloss × ... Significant loss of gloss and cracking 6) Pencil hardness: The scratch hardness of the coating film was measured using Mitsubishi Uni SQ:i under a load of 250 g.

7) Visual judgment of fleshy and double-painted belly.

O...Good 0...Slightly poor X...Defect 8) Sharpness: Visual judgment of the coating film.

■... Good condition O...Slightly poor ×...Poor

Claims (1)

[Claims] 1. (a) 1 to 20% by weight of a polymerizable unsaturated monomer having a carboxyl group (a) and 80 to 99% by weight of other polymerizable unsaturated monomers (b) (provided that , (a) + (b) is 10
Polymers (A) and (B) obtained by copolymerizing the monomer component (1) consisting of In the formula, R_1, R_2, R_3, and R_4 are each independently hydrogen, halogen, alkyl, aralkyl, phenyl, or substituted phenyl group, and R_5 is an acyclic organic group having an addition polymerizable unsaturated bond.) A polymer obtained by (co)polymerizing the monomer component (2) consisting of the addition-polymerizable oxazoline (c) represented by the expression and, if necessary, one or more other polymerizable unsaturated monomers (d). A resin composition for automobile refinish paint, characterized by containing a combination (B). 2. The resin composition for automobile refinish paint according to claim 1, wherein cyclohexyl methacrylate is used as the other polymerizable unsaturated monomer (b). 3. The resin composition for automobile refinish paint according to claim 1, wherein methyl methacrylate is used as the other polymerizable unsaturated monomer (b). 4. The resin composition for automobile refinish paint according to claim 1, wherein tert-butyl methacrylate is used as the other polymerizable unsaturated monomer (b). 5. The resin composition for automobile refinish paint according to claim 1, wherein lauryl methacrylate is used as the other polymerizable unsaturated monomer (b). 6. The resin composition for automobile refinish paint according to claim 1, wherein cyclohexyl methacrylate, methyl methacrylate, tert-butyl methacrylate and lauryl methacrylate are used in combination as the other polymerizable unsaturated monomer (b). 7. Based on the monomer component (1), 2 to 50% by weight of cyclohexyl methacrylate, 5 to 50% by weight of methyl methacrylate, 5 to 30% by weight of tertiary butyl methacrylate, and 5 to 5% of lauryl methacrylate. 3
0% by weight (however, the total amount of these monomers is the monomer component (
1), it is 17 to 99% by weight. 7. The resin composition for automobile refinish paint according to claim 6, which is used in an amount of: