US Patent 7858013 Injection molding method

Die assembly (21, 22), which includes slide die halves (23, 24) and can define a primary molding section (21a, 22a) and a secondary molding section (22b, 23b) adjacent to the primary molding section according to the positions of the slide die halves, are used. After a preformed film (10) is inserted into the primary molding section, a first resin material has been injected into the primary molding section so as to mold a first part (11), and then a second resin material is injected into a secondary molding section (22b, 23b and 23a, 24a) including a part of the surface of the film of the first part as a joint surface (10a), by which a second part (12a, 12) that is joined to the first part via the joint surface is molded.