Decorative film for insert molding, method for manufacturing decorative film for insert molding, and method for manufacturing resin molded product

A method for manufacturing a decorative film for insert molding to be formed in a three-dimensional shape before insert molding, the method comprising:

• forming, by gravure printing, a gravure print layer transmissive to visible light on a first main surface of a multilayer film, the multilayer film including a first acrylic resin layer comprising an acrylic-based resin, a second acrylic resin layer comprising an acrylic-based resin, and a first polycarbonate resin layer between the first acrylic resin layer and the second acrylic resin layer, the first polycarbonate resin layer comprising a polycarbonate-based resin, the multilayer film being transmissive to visible light;
• and
• thermally laminating a first backer film, a second backer film, and the multilayer film on which the gravure print layer is located, the first backer film comprising an acrylonitrile butadiene styrene-based resin transmissive to visible light, the second backer film including a third acrylic resin layer comprising an acrylic-based resin, a fourth acrylic resin layer comprising an acrylic-based resin, and a second polycarbonate resin layer between the third acrylic resin layer and the fourth acrylic resin layer, the second polycarbonate resin layer comprising a polycarbonate-based resin, the second backer film being transmissive to visible light,
• wherein the thermally laminating includes thermally laminating a release film, the second backer film, the first backer film, and the multilayer film under heat from a first contact heater with the first contact heater in contact with the release film, the release film in contact with the second backer film, the second backer film in contact with the first backer film, and the first backer film in contact with the multilayer film on which the gravure print layer is located, and
• the release film has a release strength with which the release film is released from the first contact heater after thermal lamination, and the release strength of the release film is lower than a release strength of the second backer film with which the second backer film is released from the first contact heater after thermal lamination performed with the first contact heater in direct contact with the second backer film.