1. Field of the Invention
The present invention concerns a composite molding comprising a silicone gel molding and a peelable film, and a method for manufacturing the same.
2. Description of the Related Art
Silicone gel moldings are superior in terms of vibration-absorbing properties, electrical characteristics, heat resistance and water resistance, etc., and are therefore used in a broad range of applications such as shock-absorbing materials, protective materials, sealing materials and soundproofing materials, etc.
However, since silicone gel moldings of this type have a strong surface tack, problems such as the adhesion of dirt and dust to the surfaces of such molding, the adhesion of such moldings to each other, and deformation resulting from the adhesion of such moldings to other materials, etc., have been encountered. Furthermore, since silicone gels themselves have a low mechanical strength, such gels are easily deformed and damaged.
Numerous methods have been proposed in the past as methods for solving such problems. For example, methods have been proposed in which an organohydrogenpolysiloxane containing silicon-bonded hydrogen atoms is applied directly to the surface of a heat-cured silicone gel molding and diffused into the surface of said silicone gel molding, after which this organohydrogenpolysiloxane is heat-cured, thus forming a hard coating film on the surface of the silicone gel molding (see Japanese Patent Application Kokoku No. 1-25704 and Japanese Patent Application Kokoku No. 6-45222). However, although the surface tack problems of silicone gel moldings obtained using such methods is ameliorated to some extent, these methods do not completely solve the abovementioned problems of adhesion of dirt and dust, adhesion of moldings to each other and deformation of moldings. In the case of such methods, furthermore, two heating processes are required; accordingly, such methods are inferior in terms of productivity, and are not satisfactory as methods for the mass production of silicone gel moldings.
Other methods of addressing the problems of dirt pick up, adhesion and deformation of silicone gel moldings are also known. In Japanese Patent Application Kokai No. 61-277414, a silicone molding in which the degree of cure varies in the direction of thickness is obtained by applying an organohydrogenpolysiloxane to the surface of a silicone gel composition which is capable of forming a silicone gel by being cured and then heating the resulting material before diffusion takes place. In Japanese Patent Application Kokai No. 5-69511 and Japanese Patent Application Kokai No 5-69512, a silicone gel molding which has a surface layer consisting of a silicone elastomer or silicone resin layer is obtained by causing a composition which forms a silicone elastomer or silicone resin layer after curing to contact the surface of a silicone gel composition, and then curing this assembly by heating. In Japanese Patent Application Kokai No. 6-88281, a silicone gel molding which has a high-hardness surface layer is obtained by pouring a silicone gel into a mold whose inside surface has been coated beforehand with an organohydrogenpolysiloxane, and then curing this assembly by heating. However, silicone gel moldings obtained using these methods suffer from the following problem: specifically, the components which form the surface layer are drawn into the silicone gel composition so that the curing of the surface layer becomes nonuniform. Furthermore, although the surface tack of silicone gel moldings obtained by the abovementioned methods is ameliorated to some extent, the abovementioned problems of adhesion of dirt and dust, adhesion of moldings to each other and deformation of moldings remain unsolved.
It is an object of the present invention to provide (a) a composite molding consisting of a silicone gel molding and a peelable film which does not suffer from the problems of adhesion of dirt and dust, adhesion of moldings to each other or deformation of moldings, and which is superior in terms of handling characteristics during storage, shipping or mounting on other materials, and (b) a method for manufacturing such a composite molding.