JPS6226333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a paint film with excellent adhesion consisting of a specific composition on a plastic product whose surface is coated with a scratch-preventing coating. YSiX ₃ (wherein, X
is a hydrolyzable group such as chlorine, an alkoxy group, or an acetoxy group; Y is a vinyl group, a methacryloxyalkyl group, a glycidoxyalkyl group, an epoxycyclohexylalkyl group, or a mercaptoalkyl group;
The present invention relates to a method for forming a film with excellent adhesion characterized by containing a silane compound represented by an organic functional group such as an aminoalkyl group, an aminoalkylaminoalkyl group, or a ureidoalkyl group. Plastics have been used for various purposes in place of metals, glass, etc., but as the demand for preventing scratches on the surface has increased, various scratch-preventing coatings have been started and used. There are various kinds of scratch-preventing coatings, but typical ones include those whose main component is melamine resin, those whose main component is polysiloxane, those whose main component is crosslinked acrylic resin, and those whose main component is crosslinked acrylic resin. There are some that consist of a mixture of. Naturally, by applying these anti-scratch coatings, it becomes less likely to be scratched by dust or scratches, but on the other hand, the problem arises that the adhesion of the paint to the coated surface decreases. . An object of the present invention is to provide a film-forming composition that has good adhesion to plastic products provided with a scratch-resistant coating. As a result of extensive research to achieve this objective, the present inventor discovered that the adhesion was dramatically improved by including the above-mentioned silane compound in the composition for forming the film, and the present invention has been made based on this finding. It was reached. The plastic products referred to in the present invention refer to general thermoplastic plastics and thermosetting plastics, but polycarbonate resins and methacrylic resins such as polymethyl methacrylate are mainly used as base materials for plastic products with scratch-prevention coatings. This makes it particularly useful for these plastic products with anti-scratch coatings. In addition, the scratch-preventing coating referred to in the present invention is one whose main component is a melamine resin, for example, etherified methylol melamine, and if necessary, nitrified cotton, polyethers, polyols, etc. are added in the presence of a catalyst. Those whose main component is polysiloxane, such as those whose main component is tetraalkoxysilane and/or alkyltrialkoxysilane and which are cured by heating in the presence of a catalyst, and those whose main component is crosslinked acrylic resin. ,
For example, the main component is an acrylic polyfunctional monomer,
Those that are polymerized and crosslinked by heat or irradiation with active energy rays in the presence of a catalyst or sensitizer by adding other copolymerizable monomers as necessary, and those that are made of a mixture of two or more of these. say.
Particularly for those whose main component is polysiloxane, the adhesion of the paint to the surface is dramatically improved. The composition for forming the film referred to in the present invention includes common paint compositions, such as phthalic acid resin paint, vinyl resin paint, epoxy resin paint, alkyd resin paint, polyurethane resin paint, nitrocellulose lacquer, and acrylic lacquer. Although a thermosetting acrylic lacquer resin paint and the like can be used, an acrylic lacquer is particularly suitable. The silane compound referred to in the present invention has the general formula
YSiX ₃ (wherein, represents an organic functional group such as a group, an aminoalkylaminoalkyl group, or a ureidoalkyl group. Propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane, γ-
Glycidoxypropyltrimethoxysilane, γ-
Examples include mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane. Among these compounds, the type of silane compound suitable for forming the film differs depending on the composition used, so it cannot be said unconditionally, but γ-aminopropyltriethoxysilane seems to give particularly favorable results. It is. The amount of the various silane compounds mentioned above added to the composition for forming a film is 300 to 0.1 part by weight, more preferably 200 to 1 part by weight, per 100 parts by weight of the binder component in the composition for forming a film. This is desirable. The amount added
If the amount is less than 0.1 part by weight, the effect of improving adhesion will be poor, whereas if the amount added exceeds 300 parts, it will adversely affect other physical properties of the coating, such as appearance and crack resistance, which is not preferable. EXAMPLES In order to make the present invention more understandable, the present invention will be explained in detail using the following examples, but the present invention is not limited to these examples. Example (1) Molding of plastic products A methacrylic resin molding material (registered trademark "SumiPex-B" manufactured by Sumitomo Chemical Co., Ltd.) was molded using an injection molding machine to form 10 cm long, 5 cm wide, and 2 cm thick.
It was molded into a plate shape of m/m to make a plastic product. (2) Implementation of scratch-prevention coating The plastic product in (1) was dipped in a paint whose main component was polysiloxane (registered trademark "Sumiuni", a product of Sumitomo Chemical Co., Ltd.), using the dipping method (pulling speed 18 cm/min). The material was coated with a hot air circulation type drying oven at 80°C for 2 hours to cure and create a plastic product with a scratch-preventing coating on the surface. (3) Preparation of composition for forming a film A composition for forming a film was prepared by adding a silane compound to the various paints shown in Table 1 in an amount shown in Table 1 based on 100 parts by weight of the binder component in the paint. (4) Measurement of film formation and adhesion on plastic products with anti-scratch coating The film-forming composition prepared in (3) was applied to the substrate in (2) with a brush, allowed to set for 10 minutes, and then heated at 60°C. Dry and harden for 2 hours in a hot air circulation heating oven, cool to room temperature, and then use a knife to cut 100 squares at 1 mm intervals on the surface of the cellophane tape (registered trademark "Cello Tape"), a product of Nichiban Co., Ltd. ), and the results are expressed as (number of squares that do not peel off)/(number of squares in total), and are shown in Table 1. 【table】

Claims (1)

[Scope of Claims] 1. A method for forming a film on a plastic product whose surface is coated with a scratch-prevention coating made of a paint containing polysiloxane as a main component, wherein the composition for forming the film is (A) an acrylic lacquer. and 100 parts by weight of at least one type of alkyd resin paint and (B) a compound having the general formula YSiX ₃ (wherein, A method for forming a film with excellent adhesion, characterized by comprising 200 to 4 parts by weight of a silane compound represented by a selected organic functional group. 2. The film forming method according to claim 1, wherein the plastic product is made of one or a mixture of two or more selected from the group of polycarbonate resins and methacrylic resins. 3. The film forming method according to claim 1, wherein the silane compound is γ-aminopropyltriethoxysilane.