A production method for a resin-molded product includes preparing a mold frame including an accommodation portion accommodating the first resin member therein, a first flow path extending in a first direction, and a second flow path extending in a second direction intersecting the first direction and making the first flow path and the first resin member in the accommodation portion communicate with each other, injecting a molten resin forming the second resin member into the first flow path and causing the molten resin to flow from the first flow path to the second flow path, contacting the molten resin and the first resin member to form a welded portion between the molten resin and the first resin member, and cooling the molten resin to form the second resin member, wherein the welded portion is formed in the second flow path.

A reuse method of a used PET film includes a removal process including mechanically removing, from the used PET film, the ceramic stuck to the surface of the used PET film, a flaking process including processing the used PET film, from which the ceramic stuck to the surface has been removed, into a flake, a first pelletizing process including processing the flake into a first pellet, an adding process including adding an anti-crystallization agent to the first pellet, a second pelletizing process including processing the first pellet, to which the anti-crystallization agent has been added, into a second pellet, and a molding process including forming a resin molded article through an injection blow molding process, from the second pellet.

A reuse method of a used PET film, with a ceramic stuck to a surface thereof, is provided. The reuse method of the used PET film includes a repelletizing process, a pellet mixing process, and a molding process. The repelletizing process includes producing a first pellet by repelletizing the used PET film. The pellet mixing process includes mixing the first pellet produced through the repelletizing process, with a second pellet containing a lower percentage of components other than PET than the first pellet. The molding process includes forming a resin molded article through an injection blow molding process, from the first pellet and the second pellet, mixed together in the pellet mixing process.

Provided is a method for recycling a used PET film with ceramic adherent to a surface thereof. The method for recycling a used PET film includes a repelleting step and a molding step. In the repelleting step, the used PET film is repelleted to make pellets. In the molding step, the pellets made in the repelleting step are used to form a resin molded product.

A technique for reducing product damage is provided. To this end, a joining resin has, in at least one of a first molded product and a second molded product, a penetration portion penetrating through the molded product in a lamination direction in which the molded products are laminated and an anchor portion having a larger cross-sectional area than the rest of the penetration portion.