JPS6315301B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating method for applying a thermosetting acrylic resin paint, a polyurethane resin paint, or an epoxy resin paint to a polyamide molded article. More specifically, as a pre-painting treatment agent,
The present invention relates to a coating method for applying a thermosetting acrylic resin paint, a polyurethane resin paint, or an epoxy resin paint using a cationic surfactant. Conventionally, when polyamide resin is used in industrial parts, it is often used for internal mechanical parts such as gears, cams, and bearings, and there has been little need to paint the product for these uses. However, recently, polyamide resin has also been used for automotive exterior parts such as air spoilers, louvers, cowl top grilles, air outlet grilles, wheel caps, bumpers, etc. that take advantage of its good heat resistance and mechanical properties (toughness, etc.). is being expanded. For painting automobile exterior parts and home appliance parts, we use thermosetting acrylic resin paints with excellent weather resistance (gloss retention, color retention) and stain resistance, and coatings with high hardness, elasticity, and resistance. Excellent abrasion resistance, chemical resistance,
Polyurethane resin paints with excellent water resistance and heat resistance, and epoxy resin paints with excellent adhesion and abrasion resistance are widely used. However, these resin coatings hardly adhere to polyamide resins.
For this reason, methods such as immersing polyamide resin in a 40% phosphoric acid aqueous solution, washing with water and drying to improve adhesion have been used, but in addition to the complexity of the process,
There were problems such as dimensional changes due to water absorption. As a result of intensive research into a simple and effective pretreatment method that does not have this drawback, the present inventor found that the use of a cationic surfactant as a pretreatment agent for polyamide moldings satisfies the purpose. Based on this knowledge, the present invention was accomplished. That is, the present invention provides a method for coating a polyamide molded article, in which a cationic surfactant is attached to the surface of the polyamide molded article to be painted, and then a thermosetting acrylic resin paint, a polyurethane resin paint, or an epoxy resin paint is applied. It is something. The polyamide molded product in the present invention can be obtained by molding polyamide, rubber and/or thermoplastic resin-added polyamide, and resins obtained by filling and reinforcing these with inorganic fillers, fibers, etc. by a method known per se. . Specific examples of polyamides include polymers such as ε-caprolactam, aminocaproic acid, ω-laurinlactam, and 1,1-aminoundecanoic acid;
Polymers obtained by polycondensing diamines such as hexamethylene diamine, nonamethylene diamine, undecamethylene diamine, and dodecamethylene diamine with dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and dodecane-2-acid; Examples include copolymers of these monomers. Specific examples of mineral fillers in mineral-filled polyamides include calcium carbonate, calcium silicate, talc, kaolin, mica, titanium oxide, alumina, ferrite, silica, carbon, and mixtures thereof. Specific examples of fibers in the fiber-reinforced polyamide include glass fibers, carbon fibers, metal fibers, boron fibers, and mixtures thereof. Specific examples of the rubber in the rubber and/or thermoplastic resin-added polyamide include ethylene propylene rubber, acrylonitrile butadiene rubber,
Examples include styrene-butadiene block copolymer rubber and hydrogenated products thereof, styrene-isoprene block copolymer rubber and hydrogenated products thereof, carboxylic acid-modified rubbers thereof, and mixtures thereof. Specific examples of thermoplastic resins include polyethylene, ethylene-vinyl acetate copolymers, polypropylene, carboxylic acid-modified products thereof (including ethylene-based ionomer resins called ionomer resins), acrylonitrile-butadiene-styrene copolymers, and their A mixture can be mentioned. Specific examples of cationic surfactants which are important constituents of the present invention include the following. Primary amines and salts thereof, such as carbon atoms of 8 to
Alkylamines with 18 alkyl groups and their acetates and hydrochlorides. Secondary amines and salts thereof, such as alkylmethylamines having an alkyl group having 8 to 18 carbon atoms, and their acetates and hydrochlorides. These are tertiary amines and salts thereof, such as alkyldimethylamines having an alkyl group having 8 to 18 carbon atoms, and their acetates and hydrochlorides. Quaternary ammonium salts, such as dialkyldimethylammonium chloride or bromide having an alkyl group having 8 to 18 carbon atoms, alkyltrimethylammonium chloride or bromide, alkylimidazolium chloride or bromide, alkyldimethylbenzylammonium chloride or bromide, polyoxy Ethylene alkyl monomethyl ammonium chloride or bromide, alkyl isoquinolinium chloride or bromide. One or more oxyethylenes are added to an alkylamine having an alkyl group having 8 to 18 carbon atoms, such as oxyethylene alkylamine, polyoxyethylene alkylamine, and polyoxyethylene alkylpropylene diamine. It is a pyridinium salt, such as an alkylpyridinium chloride or bromide having an alkyl group having 8 to 18 carbon atoms. Furthermore, amide bonds, ester bonds,
It may be an amine containing an ether bond, a quaternary ammonium salt, or a pyridinium salt. Furthermore, amphoteric surfactants having cationic activity can also be used. In particular, quaternary ammonium salts are preferred because they significantly improve adhesion. The cationic surfactant used in the present invention is usually used in the form of a solution, and solvents include water, lower alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, etc.), higher alcohols, ethers, ketones, Hydrocarbons etc. are used. Although the concentration of the solution is not limited, a solution of 0.1 to 10% by weight is preferred in order to uniformly adhere the solution to the surface of the polyamide molded article. A conventional method can be used to attach a cationic surfactant to the surface of a polyamide molded article using the above solution. For example, a method of immersing the molded article in the solution, a method of applying the solution to the surface of the molded article by spraying or brushing, or a method of applying the solution to the surface of the mold during molding by spraying or brushing and then performing molding. There is a method of attaching it to the surface of a molded article. The amount of the cationic surfactant deposited on the polyamide molded article may be 0.1 millimoles/ ^m2 or more, preferably 0.1 to 10 millimoles/ ^m2 . 0.1 millmol/
If it is less than m ² , the effect of improving the adhesion with thermosetting acrylic resin paints, polyurethane resin paints and epoxy resin paints is poor, which is not preferable. The thermosetting acrylic resin paint in the present invention is a paint made of a mixture of an acrylic resin obtained by copolymerizing an acrylic monomer having an active functional group and a crosslinking agent. Acrylic resins include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, and methacrylic acid. Acrylic monomers such as lauryl and hydroxyalkyl methacrylates,
It is a copolymer with an acrylic monomer having an active functional group, such as acrylic acid, methacrylic acid, glycidyl methacrylate, methylol acrylamide, or an etherified product of methylol acrylamide. As a crosslinking agent, amino resin, epoxy resin,
Carboxyl polymers, epoxy amino resins, etc. are used, and acids and bases are used as catalysts, if necessary. The polyurethane resin paint is a polyol-curable polyurethane resin paint. Examples of polyols include polyester polyols, acrylic polyols, polyether polyols, and the like. Polyester polyols are produced by the reaction of dibasic organic acids and glycols.
As dibasic acids, adipic acid, sebacic acid, dimer acid, phthalic anhydride, etc. are used, and as glycols, ethylene glycol, diethylene glycol, propylene glycol, trimethylolpropane, glycerin, etc. are used. Acrylic polyol is a copolymer of an acrylic monomer having a hydroxyl group and an acrylic ester.The acrylic monomer having a hydroxyl group includes 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, etc., and the acrylic ester includes acrylic ester. Methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate, etc. Alternatively, styrene may be used. Polyether polyols are obtained by reacting glycols with propylene oxide under an alkali catalyst.
As glycols, propylene glycol, glycerin, trimethylolpropane, hexanetriol, sorbitol, etc. are used. The isocyanate compound must have two or more isocyanate groups, and examples include tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), and metaxylylene diisocyanate (MXDI). ), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), hydrogenated HDI, hydrogenated TDI, hydrogenated XDI, isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), dimer acid diisocyanate (DDI), etc. It will be done. Epoxy resin paints are paints consisting of a mixture of an epoxy resin having one or more epoxy groups in the polymer molecule and a curing agent. Epoxy resins may be modified with alkyd resins, polyethylene glycols, fatty acids, coal tar, diisopropanolamine, etc., and curing agents include phenolic resins, amino resins, melamine resins, isocyanates, amines (ethylenediamine, diethylenetriamine, etc.), etc. is used. Various methods can be used for applying thermosetting acrylic resin paint, polyurethane resin paint, and epoxy resin paint.
For example, brush painting, dip painting, spray painting (air spray, airless painting, electrostatic painting), etc. Next, the present invention will be explained in more detail with reference to Examples. These examples do not limit the scope of the invention. Note that the characteristic values in the examples were measured by the following method. (1) Adhesion (a) Normal state According to JISK5400-1979, a 1 mm square grid test was conducted to determine the area percentage that did not peel off. (b) After thermal shock Thermal shock test (-30℃ x 1hr ~
After (90°C x 1 hr), a grid test was performed to determine the area percentage that did not peel off. Example 1 Nylon 66 (manufactured by Asahi Kasei Corporation, Leona
Octadecyltrimethylammonium chloride (manufactured by NOF Corporation, cationic
Using a 2% by weight solution of ethyl alcohol (AB), air spray coating was performed so that the adhesion amount was 3 millimoles/m ² to obtain a coated object. Apply thermosetting acrylic resin paint (A) to this object (manufactured by Kansai Paint Co., Ltd., Magiklon, diluted with special thinner (15 seconds/FC#4)
], same (B) (manufactured by Tokyo Paint Co., Ltd., Acrystar white, diluted with special thinner (15 seconds/FC
#4) Air spray paint with 30 minutes at room temperature.
After being left for a minute, it was cured by heating at 150°C for 30 minutes to obtain a coated product. The coating thickness of the painted object was approximately 40 μm. Table 1 shows the results of measuring the adhesion of this coated product. In addition, polyurethane resin paint (A) (manufactured by Takashi Kubo Paint Co., Ltd., Polyauto 650-110 Scarlet/Curing agent 659-009 = 4/1 (weight ratio) was applied to the object to be coated, and diluted with a special thinner (15 seconds/FC #4)
(B) (Manufactured by Tokyo Paint Co., Ltd., Urecon No. 3500
White/curing agent = 4/1 (weight ratio), diluted with special thinner (15 seconds/FC#4)), epoxy resin paint (manufactured by Kansai Paint Co., Ltd., Million No. 1A/curing agent = 4/1) (weight ratio), diluted with special thinner (15
Second/FC#4) and used) was air sprayed.
Table 1 shows the results of measuring adhesion after being left at room temperature for two weeks. Examples 2 to 6 Instead of the cationic surfactant octadecyltrimethylammonium chloride in Example 1, dodecyltrimethylammonium chloride (Cation BB, manufactured by NOF Corporation), alkyl (coconut) trimethylammonium chloride (NOF Corporation), company, cation FB), alkyl (coconut) dimethylbenzylammonium chloride (NOF Corporation, cation F ₂ -50), 1
-Hydroxyethyl 2-alkyl (beef tallow) imidazoline quaternary salt (manufactured by NOF Corporation, cationic
A coated article was prepared in the same manner as in Example 1 except that oxyethylene dodecylamine (Nimeen L-201, manufactured by NOF Corporation) was used, and the adhesion was measured. The results are shown in Table 1. Examples 7 to 10 Glass fiber reinforced nylon 66 (manufactured by Asahi Kasei Corporation, Leona) was used instead of nylon 66 in Example 1.
1300G), resin containing 30% by weight of calcium silicate in nylon 66 of Example 1, nylon of Example 1
66, 10% by weight of ethylene propylene rubber (manufactured by Japan EP Rubber Co., Ltd., EP51) and 20% by weight of ionomer resin (manufactured by DuPont, Surlyn A1706), nylon 6 (manufactured by Toray Industries, Ltd.,
A coated article was prepared in the same manner as in Example 1 except that CM1017) was used, and the adhesion was measured. The results are shown in Table 1. Comparative Examples 1 to 5 In Examples 1 and 7 to 10, coated objects to which octadecyltrimethylammonium chloride was not applied were prepared, and the adhesion was measured. The results are shown in Table 1. Comparative Examples 6 to 9 Instead of the cationic surfactant octadecyltrimethylammonium chloride of Example 1, anionic surfactants, sodium dodecylbenzenesulfonate (Nurex Spate H, manufactured by NOF Corporation), alkyl (Beef tallow) Sodium methyl taurate (Nippon Oil & Fats Co., Ltd., Diapon T-Paste), nonionic surfactant, lauric acid diethanolamide (Nippon Oil & Fats Co., Ltd., Starhome DL), polyoxyethylene nonylphenol ether (Nippon Oil & Fats Co., Ltd., Starhome DL), A coated article was prepared in the same manner as in Example 1 except that Nonion NS210 (manufactured by Yushi Co., Ltd.) was used, and the adhesion was measured. The results are shown in Table 1.

【table】

[Table] A cationic surfactant, especially a quaternary ammonium salt, attached to the painted surface of polyamide moldings has excellent adhesion with thermosetting acrylic resin paints, polyurethane resin paints, and epoxy resin paints. , it is fully usable for practical use.

Claims (1)

[Claims] 1. A method for coating a polyamide molded article, which comprises adhering a cationic surfactant to the surface of the polyamide molded article and then applying a thermosetting acrylic resin paint, polyurethane resin paint, or epoxy resin paint.