JPS637210B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for surface treatment of synthetic resin molded articles. More specifically, by applying a primer paint to the surface of a polycarbonate resin molded product before applying a top coat of surface-curing silicone resin, the paint film has excellent adhesion, is colorless and transparent, and has excellent scratch resistance, hot water resistance, weather resistance, and The present invention relates to a surface treatment method that can improve solvent resistance. In general, plastics are used for a variety of purposes because they have excellent properties such as easy moldability, light weight, impact resistance, and ease of processing.However, compared to other materials, plastics have a lower surface hardness, are easily scratched, and are resistant to solvents. The biggest drawback is that the product value tends to drop. In order to solve these drawbacks, the present inventors previously proposed applying a partially hydrolyzed condensate of alkyltrialkoxysilane to the surface of a plastic molded article and curing it (Japanese Patent Publication No. 37828/1983). However, if the plastic is polycarbonate resin, sufficient adhesion of the coating film cannot be obtained.
Therefore, it has been proposed to use a primer to further improve the adhesion of the coating film. The present inventors previously proposed the use of, for example, a partially hydrolyzed condensate of phenyltrialkoxysilane and alkyltrialkoxysilane (Japanese Patent Application No. 124897/1989) as a primer, but these primers There were drawbacks such as cracks occurring during weathering tests and poor adhesion. Therefore, the present inventors researched an even better primer to improve these drawbacks, and as a result, we found a primer with excellent paint film adhesion, colorless and transparent, scratch resistance, hot water resistance,
We have also discovered a method for surface treatment of polycarbonate resin that has excellent solvent resistance and does not reduce adhesion or cause cracks in weather resistance tests. That is, the present invention provides a surface treatment method in which a primer is applied to the surface of a polycarbonate resin molded article, heat treated, and then a paint mainly composed of a partially hydrolyzed condensate of alkyltrialkoxysilane is applied and cured. (a) 1 mol of phenyl alkoxysilane represented by the general formula C ₆ H ₅ Si (OR ¹ ) ₃ (where R ¹ is an alkyl group having 1 to 4 carbon atoms) (b) General formula R ² Si (OR ³ ₎ Partially hydrolyzed condensate of a silicon compound consisting of 0 to 10 moles of alkyltrialkoxysilane represented by 3 (where R ² and R ³ are alkyl groups having 1 to 4 carbon atoms) 100
Parts by weight, B General formula R ⁴ COOH (where R ⁴ is H or carbon number 1
A mixture consisting of a solvent containing a carboxylic acid represented by an alkyl group of 5 to 5), C: a curing catalyst, D: 1 to 10 parts by weight of an epoxy compound, and E: 0.1 to 5 parts by weight of an ultraviolet absorber. The present invention relates to a method for surface treatment of polycarbonate resin molded articles. Examples of the polycarbonate resin molded product serving as the base material in the present invention include polycarbonate resin molded products made from aromatic polycarbonates such as those obtained from bisphenol A and phosgene, aliphatic polycarbonates such as diethylene glycol bisallyl carbonate, and the like. . The primer component phenyltrialkoxysilane A) (a) used in the present invention has the general formula C ₆ H ₅ Si
(OR ¹ ) ₃ , where R ¹ is methyl, ethyl,
Examples include _C1 - _C4 alkyl groups such as propyl and butyl. A typical phenyltrialkoxysilane is phenyltriethoxysilane. The alkyltrialkoxysilane A) (b) which can be co-condensed with phenyltrialkoxysilane A) (a) is represented by the general formula R ² Si(OR ³ ) ₃ , where R ² and R ³ are methyl, ethyl, _C1 - _C4 such as propyl, butyl
An example of a typical alkyltrialkoxysilane for the alkyl group is methyltriethoxysilane. Examples of curing catalysts used in the present invention include:
tetraethylammonium hydroxide,
Quaternary ammonium hydroxide such as trimethylbenzylammonium hydroxide, γ-aminopropyltriethoxysilane, N
Aminosilane compounds such as -β-(aminoethyl)-γ-aminopropyltriethoxysilane, alkali metal salts of inorganic acids such as sodium phosphate and sodium borate, and organic carboxylic acids such as sodium acetate, sodium oleate, and sodium naphthenate. Examples include alkali metal salts of acids, tetrasodium salt of ethylenediaminetetraacetate acid (EDTA), triethylamine, organic amines such as 1,8-diazabicyclo(5.4.0)undecene-7, and cyclic amidines or their salts. The ratio of phenyltrialkoxysilane to alkyltrialkoxysilane in the partially hydrolyzed condensate of silicon compounds as component A) as a primer is 0 to 10 mol of alkyltrialkoxysilane to 1 mol of phenyltrialkoxysilane; Preferably it is 0 to 1 mol. The initial adhesion of the coating film to polycarbonate resin is excellent when the alkyltrialkoxysilane is in the range of 0 to 10 moles, but the adhesion when immersed in hot water is poor when the alkyltrialkoxysilane is 0 to 1 mole, that is, an excess of phenyltrialkoxysilane. is better. As described in Japanese Patent Publication No. 15079/1983, the partial hydrolyzed condensate of silicon compounds in A) above is
Initial hydration obtained by adding water and a small amount of acid to phenyltrialkoxysilane alone or a mixture of phenyltrialkoxysilane and alkyltrialkoxysilane, and heating the mixture under reflux at a temperature of 50 to 80°C for about 1 to 10 hours. It is a decomposition condensation product. When used as a primer, after concentrating the initial hydrolysis condensate, alcohol such as methanol, ethanol, propanol, butanol, formic acid, acetic acid,
Carboxylic acids such as propionic acid, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, ethyl lactate and butyl acetate, ether solvents such as methyl cellosolve and ethyl cellosolve, and one or more other solvents. The solution is diluted to the above amount, the ultraviolet absorber and epoxy compound are dissolved, and a surfactant, dye, etc. are added as needed. (Hereinafter, this will be referred to as liquid A). Component B) as a primer, that is, a solvent containing carboxylic acid, is formic acid, acetic acid, propionic acid, butyric acid,
It is a carboxylic acid such as valeric acid diluted with alcohol, ketone, ester, or ether solvent.
For use as a primer, this component is mixed with the above solution A). (Hereinafter, this will be referred to as liquid B). For final primer preparation, add C) to the above B) solution.
It is obtained by mixing the components, namely the curing catalyst. At this time, if you mix component C) directly into the A) solution, the solution may gel and solidify, so C)
It is better to mix the components after mixing the B) component with the A) solution to obtain the B) solution. Particularly useful among the curing catalysts mentioned above are aminosilane compounds such as γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, triethylamine, 1,8-diazabicyclo(5.4 .0) One or more of organic amines such as undecene-7, cyclic amidines, or salts thereof can be used. The amount of curing catalyst added varies depending on the type of curing catalyst, but is 0.05 to 20 parts by weight per 100 parts by weight of component A).
Parts by weight are preferred. If the amount is less than 0.05% by weight, the curing speed is slow and the adhesion is poor. If the amount exceeds 20 parts by weight, the curing speed will increase, but the water resistance will decrease. The epoxy compound as component D) in the present invention is a polyhydric phenol such as bisphenol A, catechol, and resorcinol, or a polyhydric alcohol such as (poly)ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerol, and sorbitol. polyglycidyl ether obtained from hexahydrophthalic acid and epichlorohydrin, polyglycidyl ester obtained from hexahydrophthalic acid and epichlorohydrin,
An alicyclic epoxy resin containing an epoxy group in an alicyclic ring such as -epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate can be used. Also, alkoxysilanes having an epoxy group in the molecule, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxy cyclohexyl)ethyltrimethoxysilane, β-(3,4-
Epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)
Ethylmethyldimethoxysilane and the like can also be used. Preferably, bisphenol Aγ-polyglycidyl ether or alicyclic epoxy resin can be used. The amount of component D) added is 1 to 10 parts by weight, more preferably 2 to 10 parts by weight, per 100 parts by weight of component A). If it is more than 10 parts by weight, the adhesion of the primer to the base resin will be poor, and if it is less than 1 part by weight, cracks will occur in the coated product in the weather resistance test. Examples of the ultraviolet absorber as component E) in the present invention include the following. Examples of benzophenones include 2,3'-dihydroxy-4,4-dimethoxybenzophenone, 2,
2'-dihydroxy-4-methoxybenzophenone and 2,2',4,4'-tetrahydroxybenzophenone; as benzotriazole series, 2-
(2′-hydroxy-5′-methylphenyl)-5,
6-dichlorobenzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-methyl-
3′-tert-butylphenyl)benzotriazole,
2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chloro-benzotriazole and 2-(2'-hydroxy-5'-phenyl phenyl)
-5-chlorobenzotriazole, 2(2'-hydroxy-3',5'-dithyabutylphenyl)
-5-chlorobenzotriazole, 2-(2-hydroxy-5-octoxyphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole , 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5,6-dichlorobenzotriazole, and the like are effective. Particularly effective are benzotriazole-based ultraviolet absorbers. The amount of the ultraviolet absorber as described above can vary widely depending on the type of ultraviolet absorber, the type of silicon compound used, the type of solvent, the thickness of the coating, etc., but in general, per 100 parts by weight of component A), A range of 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight is suitable. Since such ultraviolet absorbers have poor solubility in alcoholic solutions of organopolysiloxanes, they are preferably dissolved in an aromatic, ketone, or ester solvent before being added to liquid A). The solid content in the primer solution is about 1 to 40% by weight, preferably about 2 to 30% by weight, and is adjusted by the amount of the solvent of component B) added. Primer application methods include dipping, spraying, flow coating, and
The primer is applied by spin coating or the like, and then dried and cured by heat treatment. The heat treatment conditions should be below the heat distortion temperature of polycarbonate resin, usually 60℃ to 130℃.
Heat curing is performed at ℃ for 5 minutes to 12 hours. Preferably, heat curing is performed at 110 to 120°C for 10 minutes to 2 hours. As for the degree of curing, good adhesion can be obtained if the primer layer is cured to such an extent that the primer layer does not peel off when the top coat is applied. If the primer layer is cured too much, the adhesion between the top coat and the primer layer will decrease, so it is necessary to select an appropriate range for curing the primer. The coating thickness of the primer can be freely selected depending on the purpose, but it is preferably about 0.1 to 10 μm. Next, as the top coating according to the present invention, a coating mainly composed of a partially hydrolyzed condensate of alkyltrialkoxysilane is used. Here, as the alkyltrialkoxysilane, those represented by the general formula R ⁷ Si(OR ³ ) ₃ are preferably used, and R ⁷ and R ³ in the formula are C ₁ such as methyl, ethyl, propyl, butyl, etc.
~ _C4 alkyl groups are preferred, with methyltrinitoxysilane being a typical example. As described in US Pat. No. 3,389,114, it is a partially hydrolyzed condensate obtained by adding water and a small amount of acid and heating the mixture at a temperature of 50 to 80°C for 1 to 10 hours. For the purpose of improving the hardness of the coating film, tetraalkoxysilane may be mixed with alkyltrialkoxysilane and co-hydrolyzed. Further, a hydrolyzate of tetraalkoxysilane may be mixed with a hydrolyzate of alkyltrialkoxysilane for use. The concentrated alkyltrialkoxysilane partial hydrolysis condensate can be mixed with alcohols such as methanol, ethanol, propanol, and butanol, carboxylic acids such as formic acid, acetic acid, and propionic acid, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ethyl acetate, and ethyl lactate. , ester solvents such as butyl acetate, ether solvents such as methyl cellosolve, ethyl cellosolve, and other solvents.
A top coat is prepared by diluting the solution to a specific level or more, and then adding a curing catalyst, a surfactant, and if necessary, an ultraviolet absorber, a dye, and other additives. Curing catalysts added for the purpose of accelerating the curing of the coating film include quaternary ammonium hydroxide such as tetraethylammonium hydroxide and trimethylbenzyl hydroxide;
Alkali metal salts of inorganic acids such as sodium phosphate and sodium borate; alkali metal salts of organic carboxylic acids such as sodium acetate, sodium oleate and sodium naphthenate; tetrasodium salt of ethylenediaminetetraacetate acid (EDTA); Triethylamine, 1,8-diazabicyclo(5,4,
0) Examples include organic amines such as undecene 7, cyclic amidines, or salts thereof. The solid content in the top coat is about 1 to 40% by weight, preferably about 10 to 30% by weight. The present invention is achieved by applying this top coat paint to a polycarbonate resin molded product etc. that has been coated and cured with the primer by a method such as a dipping method, a spray method, a flow coating method, or a spin coating method, and then drying and curing by heating. . The film thickness of the top coat varies depending on the application of the coated material, but is usually 1 to 20 microns. The usual heat curing conditions are 50 to 140°C for 15 minutes to 12 hours, preferably 80 to 130°C for 2 to 5 hours. Polycarbonate resin molded products obtained by the present invention have excellent coating film adhesion, scratch resistance, hot water resistance, weather resistance, and solvent resistance, so they can be used in automobiles, trains, etc.
Aircraft window glass, building window glass, ski goggles, sunglass lenses, protective eyewear lenses,
Useful for preventing scratches on prescription eyeglass lenses and optical equipment lenses. The present invention will be explained below with reference to Examples. Example 1 720 g (3 moles) of phenyltriethoxysilane, 160 g (9 moles) of water, and 1 c.c. of 0.1N hydrochloric acid were placed in a reactor equipped with a reflux condenser, mixed well, and heated under reflux for 4 hours. The liquid, which was initially a non-uniform layer, became a uniform layer. Next, ethanol was removed by distillation and the mixture was concentrated to obtain a solid product of a partially hydrolyzed condensate of phenyltriethoxysilane. 100 parts (hereinafter referred to as parts by weight) of a partially hydrolyzed condensate of phenyltriethoxysilane (solid), 6 parts of Epicote 828 (manufactured by Ciel Chemical; trade name of bisphenol A polyglycidyl ether),
and 1.2 parts of Tinuvin 327 (manufactured by Ciba Geigy; trade name of benzotriazole ultraviolet absorber) with n-
300 parts of butanol was dissolved and 30 parts of acetic acid was added. Cool this to below 20°C and add γ-aminopropyltriethoxysilane 16 on top of it while stirring.
1 part was gradually added, and further 7 parts of water were added and mixed well to prepare a primer solution. The viscosity of the primer solution was measured with a Bruckfield viscometer and was 10 centipoise at 20°C. Next, a top coat was prepared as follows. 356 g (2 moles) of methyltriethoxysilane, 108 g (6 moles) of water, and 1 c.c. of 0.1N hydrochloric acid were thoroughly mixed and heated under reflux for 4 hours. Next, ethanol was removed by distillation to obtain a partially hydrolyzed condensate of methyltriethoxysilane. 30 parts of partially hydrolyzed condensate of methyltriethoxysilane, 50 parts of industrial ethanol, 20 parts of acetic acid, 1.0 parts of tetraethylammonium hydroxide
% aqueous solution and 0.5 part of a surfactant were thoroughly mixed to prepare a top coat. A 100 x 100 x 2 mm polycarbonate resin sheet was washed and dried, immersed in the primer solution, and pulled up at a pulling speed of 20 cm/min without vibration. It was immediately placed in a hot air dryer and heated at 120°C for 1 hour. The primer-coated sheet was then dipped into the top coat and pulled up at a pulling speed of 20 cm/min without vibration. Immediately put it in a hot air dryer.
It was heated at 90° C. for 5 hours to obtain a polycarbonate sheet having a surface hardened film. This coating sheet was evaluated by the following method. The results are shown in Table 1. 1 Measurement of abrasion resistance Weared wheels were measured using a taper mamo tester (manufactured by Yasuda Seiki).
The surface of the coating sheet was scratched under the conditions of CS-10F load of 500g and 100 cycles. Next, total light transmittance and scattered light were measured using a haze meter (manufactured by Suga Test Instruments), and scratch resistance was expressed as haze (%) = scattered light/total light transmittance x 100. 2. Initial Adhesion The sheet was placed on a cross-cut tester (manufactured by Toyo Seiki) and fixed, and a single-edged razor was applied with a load of 200 g to make 11 vertical and horizontal cuts at 1 mm intervals to create cross hatches. A cellophane adhesive tape was pasted on the crosshatch, and the tape was strongly pulled in a direction perpendicular to the sheet to observe the peeling state of the paint film. It is expressed as the number of squares remaining (numerator) out of 100 crosshatch squares (denominator). 3. Hot water resistance After immersing the coating sheet in hot water at 100°C or 60°C, the same procedure as the initial adhesion test was conducted, and the test was expressed as the time at which the adhesion started to decrease. 4 Weather resistance test A weather resistance test was conducted using a sunshine in-type weather meter, and the same as the initial adhesion test was conducted.
It is expressed as the weather meter irradiation time at which adhesion begins to deteriorate. The time required for craze to occur on the coated surface of the sheet is also displayed. 5 Solvent resistance Place acetone on the sheet to the extent that it does not flow.
It is expressed as the time until blistering or peeling occurs on the paint film. If the acetone evaporates and becomes low, add more acetone. Example 2 In Example 1, phenyltriethoxysilane
The same procedure as in Example 1 was carried out except that 960 g (4 moles) of phenyltriethoxysilane and 178 g (1 mole) of methyltriethoxysilane were used instead of 720 g (3 moles). The results are shown in Table 1. Example 3 In Example 1, phenyltriethoxysilane
The same procedure as in Example 1 was carried out except that 240 g (1 mol) of phenyltriethoxysilane and 356 g (2 mol) of methyltriethoxysilane were used instead of 720 g (3 mol). The results are shown in Table 1. Example 4 The same procedure as in Example 2 was carried out, except that 3 parts of Epicote 828 (product of Ciel Corporation; bisphenol A type epoxy resin) was used instead of 6 parts. The results are shown in Table 1. Example 5 In Example 2, N-β-(aminoethyl)-γ was used instead of γ-aminopropyltriethoxysilane.
The same procedure as in Example 2 was carried out except that -aminopropyltriethoxysilane was used. The results are shown in Table 1. Example 6 The same procedure as in Example 2 was carried out except that 70.3 parts of 1,8-diazabicyclo(5.4.0) undecene was used instead of γ-aminopropyltriethoxysilane. The results are shown in Table 1. Example 7 In Example 2, Epicote 828 (manufactured by Ciel Chemical; bisphenol A polyglycidyl ether)
The same procedure as in Example 2 was carried out except that 6 parts of γ-glycidoxypropyltrimethoxysilane was used instead of . The results are shown in Table 1. Example 8 Example 2 except that Tinuvin p (manufactured by Ciba Geigy; a benzotriazole ultraviolet absorber) was used instead of Tinuvin 327 (manufactured by Ciba Geigy; a benzotriazole ultraviolet absorber).
I did the same thing. The results are shown in Table 1. Example 9 The same procedure as in Example 2 was carried out except that a polydiethylene glycol bisallyl carbonate plate was used instead of the polycarbonate sheet used in Example 2. The results are shown in Table 1. Comparative Example 1 In Example 1, Epicote 828 (manufactured by Ciel Chemical; bisphenol A polyglycidyl ether)
The same procedure as in Example 1 was carried out except that 20 parts were added instead of 6 parts. The results are shown in Table 1. Comparative Example 2 Various tests were conducted on the original polycarbonate as it was. The results are shown in Table 1. Comparative Example 3 The same top coat as in the example was applied to a polycarbonate sheet without using a primer, and then heated and cured in the same manner. The results are shown in Table 1. Comparative Example 4 The same procedure as in Example 1 was carried out except that γ-aminopropyltriethoxysilane was applied instead of the primer paint of Example 1. The results are shown in Table 1.

【table】

【table】

Claims (1)

[Scope of Claims] 1. Surface treatment of a polycarbonate resin molded product, in which a primer is applied to the surface of the polycarbonate resin molded product, heated, and then a paint mainly composed of a partial hydrolyzate of alkyltrialkoxysilane is applied and cured. In the method, the primer is (a) having the general formula C ₆ H ₅ Si(OR ¹ ) ₃ (wherein R ¹ has a carbon number of 1 to
1 ^mol of ^{phenyltrialkoxysilane} _represented by the ^alkyl group ^of
a partial hydrolyzed condensate of a silicon compound consisting of 0 to 10 moles of alkyltrialkoxysilane represented by (-4 alkyl groups); a curing catalyst;
A method for surface treatment of polycarbonate resin molded articles, characterized by using a mixture consisting of an epoxy compound and an ultraviolet absorber. 2. Claims characterized in that the primer is prepared in a solvent containing a carboxylic acid represented by the general formula R ⁴ COOH (where R ⁴ is H or an alkyl group having 1 to 5 carbon atoms) The method described in paragraph 1. 3. A primer comprising 100 parts by weight of a partially hydrolyzed condensate of a silicon compound, 0.05 to 20 parts by weight of a curing catalyst, 10 parts by weight of an epoxy compound 1, and 0.1 to 5 parts by weight of an ultraviolet absorber. The method according to scope 1 or 2.