JPS6154063B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermosetting aminoacrylic resin-based two-coat one-bake solid color coating composition containing a colored pigment and an ultraviolet absorber. The objective is to improve weather resistance defects such as cracking, blistering, discoloration, and fading caused by outdoor exposure, which are considered to be film defects of conventional two-coat one-bake paints, and to improve interlayer adhesion. The purpose of the present invention is to provide a paint composition that can be measured.

In recent years, in order to streamline and simplify the process for topcoating automobiles, etc., after applying the basecoat enamel, it is left to stand at room temperature or heated for several minutes, and then the topcoat clear is applied while the painted surface is still uncured. A two-coat, one-bake coating method is used, which is a so-called wet-on-wet method in which coating is applied and then heated and cured.

However, in the conventional two-coat, one-bake paint film, the base coat and top coat do not maintain mutual compatibility, so the dynamic elastic modulus, thermal expansion coefficient, rigidity modulus, Young's modulus, and Differences in physical properties, such as moisture permeability, breaking strength, and glass transition temperature, combine to create blisters at the interface between the base coat and top coat, resulting in peeling of the top coat or cracking of the top coat itself. Coating film defects such as peeling and peeling were likely to occur. In addition, since the top coat allows ultraviolet rays to pass through, the colored pigments in the base coat are photochemically changed by the ultraviolet rays, causing discoloration and fading.In addition, the ultraviolet rays also act on the paint film, causing deterioration, cracking, and peeling. The weather resistance was not sufficient due to factors such as the promotion of weathering.

The present invention solves the above defects by reducing the styrene component in the thermosetting acrylic resin used for the base coat and top coat, thereby improving the weather resistance of the paint film and making it possible to obtain a wet-on-wet paint film. In addition to maintaining mutual compatibility between the base coat and top coat coatings and providing interlayer adhesion between the base coat and top coat layers, a UV absorber is added to each of the base coat and top coat to eliminate the effects of UV rays, and the top coat is colored. The aim was to create a new shaping effect on the coated surface through interaction with the colored pigments in the base coat.

That is, the present invention provides a 2-coat, 1-bake type paint used in a wet-on-wet topcoat finish, which includes (1) (a) 10 to 50% by weight of melamine resin and 0 to 30% by weight as a copolymer component; 100 parts by weight of a resin mixture consisting of 90 to 50% by weight of a thermosetting acrylic resin with a glass transition temperature of 0 to 40°C containing styrene, (b) 1 to 300 parts by weight of a coloring pigment, and (c) 0.5 part by weight of an ultraviolet absorber. Solid color enamel for base coat (2) consisting of ~10 parts by weight (a) Contains 10 to 50% by weight of melamine resin and 0 to 30% by weight of styrene as a copolymer constituent, glass transition temperature -10 to 30°C A combination of a cloudy clear for top coat consisting of 100 parts by weight of a resin mixture consisting of 90 to 50 parts by weight of a thermosetting acrylic resin, (b) 0.1 to 10 parts by weight of a colored pigment, and (c) 0.5 to 10 parts by weight of an ultraviolet absorber. This is a two-coat, one-bake type solid color coating composition, and the coating film obtained from this coating composition has greatly improved weather resistance such as cracking, blistering, discoloration, and fading.

The weight ratio of the melamine resin and thermosetting acrylic resin used in the solid color enamel for base coat of the present invention (hereinafter referred to as base coat enamel) is limited to a range of 10/90 to 50/50, and this ratio is 10/90 to 50/50. If it is less than 90, the hardness of the coating film required for practical use cannot be obtained, and if it exceeds 50/50, the necessary flexibility of the coating film cannot be obtained.

The thermosetting acrylic resin used in the above base coat enamel has a copolymer component of 0 to 0.
Glass transition temperature 0 containing 30% styrene by weight
Limited to ~40℃. Styrene in resin is 30
If the percentage by weight is exceeded, the tertiary hydrogen of styrene is activated by ultraviolet rays and becomes free radicals, which significantly accelerates the deterioration of the resin skeleton, which cannot be prevented even with ultraviolet absorbers. I can't. Furthermore, if the glass transition temperature is less than 0°C, the hardness of the final coating film required for practical purposes cannot be obtained, and if it exceeds 40°C, the flexibility of the coating film is lost, resulting in the invention of the present invention. It is not possible to prevent the paint film from cracking, blistering, peeling, etc. Note that this resin can be manufactured by a general solution polymerization method.

The polymerization ratio of the melamine resin and thermosetting acrylic resin used in the cloudy clear for top coat of the present invention (hereinafter referred to as cloudy top coat clear) is 10/90 to 50/50 for the same reason as the base coat enamel. limited to.

The thermosetting acrylic resin used in the above-mentioned top coat cloudy clear has a styrene content of 0 to 30% by weight in the copolymer components for the same reason as the thermosetting acrylic resin used in the base coat enamel. The glass transition temperature is limited to -10 to 30°C. Further, this resin can be manufactured by a general solution polymerization method similar to the thermosetting acrylic resin for base coat enamel.

The melamine resin used in the base coat enamel and top coat cloudy clear of the present invention is
Butoxymethylolmelamine resin, which is commonly used for paints, can be used.

The ultraviolet absorber used in the present invention absorbs ultraviolet rays of 290 to 315 nm present in the sun's rays, is uniformly dispersed in the resins used for base coat enamel and top coat cloudy clear, and is stable at the curing temperature of the paint. Preferably, those that do not decompose. Examples include phenyl salicylate compounds such as phenyl salicylate, p-octylphenyl salicylate, 4-t-butylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-
Hydroxy-4-methoxybenzophenone, 2.
2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, sodium-2.
2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2-hydroxy-4-oxybenzylbenzophenone, 2,2'-4,4'-tetrahydroxybenzophenone, 4-do Dehydroxy-2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2-hydroxy-4-methoxy-4'-chlorobenzophenone, 2,2'-dihydroxy-4-n-octoxy benzophenone compounds such as benzophenone,
2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-4'-
n-octyloxyphenyl)benzotriazole, 2-(2'-hydroxy-3', 5'-di-t-butylphenyl)-5-chlorobenzotriazole,
Benzotriazole compounds such as 2-(2'-hydroxy-3', 5'-di-t-amyl phenyl)-2-hydroxybenzotriazole, other bis-octylphenyl sulfides,
[2,2'-thio-bis-(4-t-octylphenolate)]-n-butylamine nickel, nickel dibutyl dithiocarbamate, etc., and one or more of these are used in the base coat enamel and top coat cloudy clear. In each case, 0.5 to 10 parts by weight are used per 100 parts by weight of the resin solid content. If the amount is less than 0.5 parts by weight, there will be no effect of absorbing ultraviolet rays, and if it exceeds 10 parts by weight, the cost will increase and the original coating performance will be impaired. Among these ultraviolet absorbers, benzotriazole-based ones are preferred because they have the best weather resistance.

As a method of adding an ultraviolet absorber to a paint, the ultraviolet absorber is dissolved in an organic solvent that serves as a solvent for the paint, and the solution is added to the paint to uniformly disperse it.
Since many ultraviolet absorbers are soluble in organic solvents such as ketonic acids, esters, and alcohols, the above operation becomes possible by selecting an appropriate organic solvent.

As the coloring pigment used in the present invention, those commonly used for conventional paints can be used.
The most appropriate blending amount for base coat enamel is 1 to 300 parts by weight per 100 parts by weight of the resin solid content; if the blending amount is less than 1 part by weight, the hiding power of the coating film will be poor; If the amount exceeds 1 part by weight, the smoothness of the coating film will be poor, which is not preferable. In top coat cloudy clear, the resin solid content
The best amount is 0.1 to 10 parts by weight per 100 parts by weight; if the amount is less than 0.1 parts by weight, the weather resistance will be poor, and if it exceeds 10 parts by weight, the gloss of the coating will decrease. .

Further, additives such as an antioxidant, a surface conditioner, an anti-sagging agent, and an anti-repellent agent may be added to the coating composition of the present invention, if necessary.

The coating composition of the present invention can be produced by a generally known coating production method. That is,
A predetermined coloring pigment, an organic solvent solution of the above resins (hereinafter referred to as resin solution), and an organic solvent if necessary are added and mixed, and then a dispersion machine such as a sand grinder, pebble mill, ball mill, or roll mill is used to disperse the required amount. After dispersing to a particle size, a required amount of ultraviolet absorber solution is added, and if necessary, the above-mentioned additives, resin solution and organic solvent are added and mixed to produce the product.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the Examples are not intended to limit the present invention.
Note that parts and % in the examples indicate parts by weight and % by weight.

Example 1 (1) Production of thermosetting acrylic resin for base coat enamel Styrene 7%, methyl methacrylate 56%,
A mixture of 7% butyl methacrylate, 22% 2-ethylhexyl acrylate, 7% 2-hydroxy methacrylate and 1% acrylic acid was used as a polymerization initiator using t-butyl peroxybenzoate, butanol 30%: xylol 70%
copolymerized in a mixed solution of
Acrylic resin solution ACB- at 28℃, heating residue 60%, acid value 10, viscosity (Gardner viscosity/25℃)
I got 1.

(2) Production of base coat enamel A base coat enamel of the following formulation using acrylic resin solution ACB-1 was dispersed and produced using a ball mill.

Blended acrylic resin solution ACB-1 47.3 parts Supervecamine J820-60 (Note 1) 15.8 parts Permanent Carmine BST (Note 2) 9.7 parts Ultraviolet absorber solution-A (Note 3) 10.0 parts Isobutyl acetate 17.2 parts (Note 1) ) Butylated melamine resin 60% solution, trade name, Dainippon Ink & Chemicals Co., Ltd. (Note 2) Organic red pigment, trade name, Dainichiseika Co., Ltd.
(Note 3) 2-(2′-hydroxy-3′・5′-di-t)
A solution of 10 parts of -butylphenyl)-5-chlorobenzotriazole added to 90 parts of xylol, followed by 72 parts of xylol and 20 parts of isobutyl acetate.
8 parts, ethylene glycol monobutyl ether
The viscosity (Food cup #4/20°C) was adjusted to 14 seconds using mixed solvent A consisting of

(3) Production of thermosetting acrylic resin for top coat cloudy clear 27% methyl methacrylate, 18% butyl acrylate, 2-ethylhexyl methacrylate
35%, 2-hydroxyethyl methacrylate 18
% and 2% acrylic acid were copolymerized in the same manner as the thermosetting acrylic resin for base coat enamel, with a glass transition temperature of 15°C and a heating residue of 60°C.
%, acid value 9, viscosity (Gardner viscosity/25℃) Y
An acrylic resin solution ACT-1 was obtained.

(4) Manufacture of top coat cloudy clear A cloudy clear with the following formulation using acrylic resin ACT-1 was dispersed and manufactured using a ball mill.

Mixed acrylic resin solution ACT-1 60.0 parts Supervetsucomin J820-60 20.0 parts Rubicron R451R (Note 4) 1.5 parts Ultraviolet absorber solution-B (Note 5) 5.0 parts n-butanol 13.5 parts (Note 4) Organic red Pigment, product name, Toyo Soda Co., Ltd.
(Note 5) 2-(2′-hydroxy-3′・5′-di-t)
A solution prepared by adding and dissolving 10 parts of -amylphenyl)-2-hydroxybenzotriazole in 90 parts of xylene, followed by 70 parts of Solbetsuso #100 (trade name, manufactured by Shell Oil Co., Ltd.), 15 parts of n-butanol, and 15 parts of isobutyl acetate. The viscosity (Food Cup #4/20°C) was adjusted to 25 seconds using mixed solvent B.

(5) Preparation and performance of coating film A base coat enamel was applied to a test plate (hereinafter referred to as the test plate) which was prepared by coating a zinc phosphate-treated mild steel plate with an electrocoated primer and then an intermediate coat of Surfacer and then heating and hardening it. 61 spray gun (trade name, manufactured by Iwata Painting Machinery Co., Ltd.), and leave it for 1 minute at room temperature. Apply cloudy clear using the same Wider 61 spray gun, leave it for 10 minutes, and then bake dry. Heat curing was performed in a furnace at 140°C for 20 minutes.

The obtained coating was exposed outdoors for 24 months in Miami, Florida, USA, to test its weather resistance.The color difference (E) from before exposure was 1.41 NBS, and the change in color was very small, and cracks in the coating film were observed. No phenomena such as swelling, peeling, etc. were observed.

Example 2 (1) Production of base coat enamel A base coat enamel of the following formulation using the acrylic resin solution ACB-1 of Example 1 was produced by dispersing it using a roll mill.

Mixed acrylic resin solution ACB-1 30.0 parts Supervetsucomin J820-60 10.0 parts Paliotol Yellow 0960HD (Note 6) 25.0 parts Ultraviolet absorber solution-A 10.0 parts Isobutyl acetate 25.0 parts (Note 6) Organic yellow pigment, product Name, manufactured by BASF Corporation, followed by 60 parts of xylene and 30 parts of isobutyl acetate.
parts, ethylene glycol monobutyl ether 10
The viscosity (Food Cup #4/20°C) was adjusted to 16 seconds using mixed solvent C consisting of

(2) Production of thermosetting acrylic resin for top coat cloudy clear 9% styrene, 28% butyl methacrylate,
A mixture of 23% butyl acrylate, 19% 2-ethylhexyl methacrylate, 19% 2-hydroxyethyl methacrylate, and 2% acrylic acid was copolymerized in the same manner as in Example 1, glass transition temperature 0°C, heating residue 60%, acid Acrylic resin solution ACT with value 10 and viscosity (Gardner viscosity/25℃) U
-2 was obtained.

(3) Manufacture of top coat cloudy clear A cloudy clear with the following formulation using acrylic resin solution ACT-2 was dispersed and manufactured using a roll mill.

Mixed acrylic resin solution ACT-2 53.7 parts Supervetsucomin J820-60 23.0 parts Paliotol Yellow 0960HD 3.5 parts Ultraviolet absorber solution-B 5.0 parts n-butanol 14.8 parts #4/20°C) was adjusted to 30 seconds.

(4) Preparation and performance of coating film Base coat enamel and cloudy clear were coated on a test plate in the same manner as in Example 1 and cured by heating.

The obtained coating was exposed outdoors for 24 months in Miami, Florida, USA, to test its weather resistance, and the color difference (E) from before exposure was 1.34 NBS. No phenomena such as swelling, peeling, etc. were observed.

Example 3 (1) Production of thermosetting acrylic resin for base coat enamel 45% methyl methacrylate, 18% butyl methacrylate, 2-ethylhexyl acrylate
27%, 2-hydroxyethyl methacrylate 9
% and 1% acrylic acid were copolymerized in the same manner as in Example 1, glass transition temperature 9°C, heating residue 60%, acid value 10, viscosity (Gardner viscosity/25
℃)V acrylic resin solution ACB-2 was obtained.

(2) Production of base coat enamel A base coat enamel of the following formulation using acrylic resin solution ACB-2 was dispersed and produced using a pebble mill.

Mixed acrylic resin solution ACB-2 55.0 parts Supervetsucomin J820-60 23.6 parts Heliogen Blue 6900 (Note 7) 1.9 parts Ultraviolet absorber solution-A 10.0 parts Isobutyl acetate 9.5 parts (Note 7) Organic blue pigment, product Name: Hoechst Co., Ltd.
Preparation Next, the viscosity (Food Cup #4/20°C) was adjusted to 15 seconds using the mixed solvent A of Example 1.

(3) Manufacture of top coat cloudy clear A cloudy clear having the following formulation using the acrylic resin solution ACT-1 of Example 1 was dispersed and manufactured using a pebble mill.

Mixed acrylic resin solution ACT-1 61.6 parts Supervetsucomin J820-60 20.5 parts Hostogen Blue RGA (Note 8) 0.2 parts Ultraviolet absorber solution-B 5.0 parts n-butanol 12.7 parts (Note 8) Organic blue pigment, Trade name: Dainippon Ink & Chemicals Co., Ltd. Next, the viscosity (Food Cup #4/20°C) was adjusted to 27 seconds using the mixed solvent B of Example 1.

(4) Preparation and performance of coating film Base coat enamel and cloudy clear were coated on a test plate in the same manner as in Example 1 and cured by heating.

The obtained coating was exposed outdoors for 24 months in Miami, Florida, USA, to test its weather resistance.The color difference (E) from before exposure was 1.41 NBS, and the change in color was very small, and cracks in the coating film were observed. No phenomena such as swelling, peeling, etc. were observed.

Example 4 (1) Production of base coat enamel A base coat enamel of the following formulation using the acrylic resin solution ACB-2 of Example 3 was produced by dispersing it using a pebble mill.

Blended acrylic resin solution ACB-2 23.0 parts Super Betsukamine J820-60 7.5 parts Titanium oxide JR-602 (Note 9) 11.0 parts Mapico Yellow LLXLO (Note 10) 44.0 parts Ultraviolet absorber solution-A 10.0 parts Isobutyl acetate 4.5 parts ( Note 9) Product name, Teikoku Kako Co., Ltd. (Note 10) Yellow iron oxide, product name, Titanium Kogyo Co., Ltd. Next, the viscosity (foed cup #4/20°C) was adjusted to 15 with mixed solvent A of Example 1. Adjusted so that it was seconds.

(2) Manufacture of top coat cloudy clear A cloudy clear having the following formulation using the acrylic resin solution ACT-2 of Example 2 was dispersed and manufactured using a pebble mill.

Mixed acrylic resin solution ACT-2 56.2 parts Super Betsukamine J820-60 24.0 parts Titanium oxide JR-602 0.2 parts Mapico Yellow LLXLO 0.6 parts Ultraviolet absorber solution-B 5.0 parts n-butanol 14.0 parts Next, the mixed solvent B of Example 1 The viscosity (food cup #4/20°C) was adjusted to 30 seconds.

(3) Preparation and performance of coating film Base coat enamel and cloudy clear were coated on a test plate in the same manner as in Example 1 and cured by heating.

The obtained coating material was exposed outdoors for 24 months in Miami, Florida, USA, to test its weather resistance.The color difference (E) from before exposure was 1.30NBS, and there was very little change in color, and cracks in the coating film, No phenomena such as swelling or peeling were observed.

Claims (1)

[Claims] 1. Wet-on coating in top coat finish
In the two-coat one-bake type paint used in the wet method, (1) (a) a melamine resin with a glass transition temperature of 0 to 40°C containing 10 to 50% by weight of melamine resin and 0 to 30% by weight of styrene as a copolymer component; A solid color enamel for base coat consisting of 100 parts by weight of a resin mixture consisting of 90 to 50 parts by weight of a thermosetting acrylic resin, (b) 1 to 300 parts by weight of a colored pigment, and (c) 0.5 to 10 parts by weight of an ultraviolet absorber. 2) (a) 10 to 50% by weight of a melamine resin and 90 to 50% by weight of a thermosetting acrylic resin with a glass transition temperature of -10 to 30°C containing 0 to 30% by weight of styrene as a copolymer constituent. 100 parts by weight of a resin mixture, (b) 0.1 to 10 parts by weight of a colored pigment, and (c) 0.5 to 10 parts by weight of an ultraviolet absorber.