This invention relates to a process for producing a container for a photographic film.
Heretofore, containers for a photographic film were injection-molded by a multicavity mold having a number of cavities of not less than 12 in a hot runner type at a molding cycle time of not more than 10 seconds from polypropylene resin having a melt flow rate(MFR, ASTM D 1238) of 16 to 80 g/10 minutes, as disclosed in Japanese Patent KOKOKU 2-38939.
In the above conventional process, molding troubles, such as short shot, weld lines, burrs, stringiness and pinholes at resin gate portion, occurred at a rate of about 0.07%, and all of the molded products are inspected visually. Although a checking apparatus of pinholes has been developed as disclosed in Japanese Patent KOKAI 61-89551, the pinhole checking apparatus occasionally troubled by the occurrence of abrasion and biting. Moreover, burrs, stringiness and the like must be checked by visual inspection.
USPTO Backgrounds
USPTO Backgrounds