JPS6357456B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for adhering resin molded articles to which a mold release agent is attached. The surface of resin molded products, including elastic materials and low-foam materials made by injecting thermosetting resins and liquid rubbers that are liquid at room temperature such as urethane and epoxy resins into molds, and hardening them, is coated with molds in advance during molding. Usually, 5 to 20 g/m ² of a silicone-based or wax-based mold release agent is applied to the surface. Conventionally, in order to bond these resin molded products with a mold release agent attached, a pure frame was used after the process of removing the mold release agent, such as washing with a solvent, sanding, or cutting, since ordinary adhesives do not bond. The method involved applying adhesive to the resin surface. An object of the present invention is to develop an adhesive that can adhere even if a mold release agent is attached to the surface of a resin molded product, and to provide a method for bonding resin molded products that can omit the step of removing the mold release agent. The present invention is a method for bonding resin molded articles using an adhesive containing an epoxy resin-polyamide resin as a main component and 1 to 20 parts of benzyl alcohol added in terms of solid content weight. The epoxy resin used in the present invention has a highly reactive three-membered ring epoxy group in one molecule, such as glycidyl ether type, glycidyl ester type, glycidyl amine type, linear aliphatic epoxide type, and alicyclic epoxide type. It refers to those that have one or more amines, single substances such as copolymers with urethane resins, copolymers with acrylic resins, etc., and those that cure by crosslinking with amines, but among these, epibis type is the best. Next, polyamide resin consists of dimer acid and ethylenediamine obtained by thermally polymerizing drying oil, semi-drying oil, tall oil, etc.
It is a resin obtained by condensing alkylene polyamines such as diethylenetriamine and triethylenetetramine, and is traditionally used as a curing agent for epoxy resins.Among these, low molecular weight polyamides with an amine value of 600 or more Amines are the best. Next, pbenzyl alcohol is an industrial product used as a volatile retention agent, paint, solvent, and raw material for ester production. 1 to 20 copies are effective. That is, if it is less than 1 part, no adhesive effect is observed, and if it is more than 20 parts, the cohesive force of the adhesive layer becomes weak and sufficient adhesive strength cannot be obtained. It also includes adhesive compositions modified by adding known compounding agents such as curing accelerators, plasticizers, extenders, fillers, etc. according to the purpose, if necessary. In the present invention, a polyamide resin, which is a curing agent component of an epoxy resin, in particular a low molecular weight polyamide amine with an amine value of 600 or more, and benzyl alcohol dissolve the mold release agent adhering to the surface of the resin molded product and bond it. It is thought that it is absorbed and dispersed in the layer and exhibits the inherent adhesion of epoxy resin at the adhesive interface, and this effect is exhibited in the coexistence of polyamide resin and benzyl alcohol. As molding agents, both silicone-based and wax-based molding agents are found to be effective. As described above, in the present invention, by using a special adhesive, resin molded articles to which a mold release agent is attached can be bonded, and the step of removing the mold release agent can be omitted. Therefore, it is of great industrial value since it is possible to simplify the process of combining the resin molded product with other adherends such as metal, glass, wood, etc. by adhesive processing. Next, the present invention will be explained by examples. Parts indicate parts by weight. Examples 1, 2, 3 and Comparative Example 1 A bisphenol A type epoxy resin with an epoxy equivalent of about 190, a polyamide resin with an amine value of about 900, benzyl alcohol, and heavy calcium carbonate were mixed and prepared as shown in Table 1. Adhesives were prepared and used as adhesives for Examples 1, 2, and 3 and Comparative Example 1. Next, a 4 mm thick hard urethane resin molding coated with a silicone mold release agent of approximately 10 g/m ² and a wax type mold release agent of approximately 30 g/m ² was applied to a 0.3 mm thick galvanized iron plate.
Table 2 shows the results of measuring the tensile shear adhesive strength at room temperature after bonding with a spacer interposed so that the thickness of the adhesive layer was 1 mm and curing at 60° C. for 20 minutes. Comparative Example 2 In Example 2, instead of benzyl alcohol,
An adhesive of Comparative Example 2 was prepared using xylene, which can serve as a solvent for a mold release agent. Comparative Example 3 In Example 2, instead of benzyl alcohol,
An adhesive of Comparative Example 3 was prepared using mineral spirits that can be used as a solvent for a mold release agent. Comparative Example 4 In Example 2, instead of benzyl alcohol,
An adhesive of Comparative Example 4 was prepared using methyl ethyl ketone, which can serve as a mold release agent and a solvent for either epoxy resin or polyamide resin. Comparative Example 5 In Example 2, instead of benzyl alcohol,
An adhesive of Comparative Example 5 was prepared using trichlorethylene, which can serve as a mold release agent and a solvent for both epoxy resins and polyamide resins. Next, the adhesive strength of each adhesive of Comparative Examples 2, 3, 4, and 5 was measured using the same test piece and test method as in Example 1, but in all cases, the adhesive strength was determined by interfacial peeling from the resin molded product. Nakatsuta.

【table】

[Table] *marked is broken from urethane resin

Claims (1)

[Scope of Claims] 1. When bonding a resin molded product to which a mold release agent is attached, an adhesive made of an epoxy resin-polyamide resin as a main component with 1 to 20 parts of benzyl alcohol added in terms of solid content weight. A method for adhering resin molded articles, characterized by using an adhesive. 2. The method for bonding resin molded articles according to claim 1, wherein the polyamide resin is a low molecular weight polyamide amine with an amine value of 600 or more.