| 摘要 |
PURPOSE:To provide the title cap which can be produced inexpensively in good efficiency and is excellent in fitting strength, sealability, etc., at low and high temperatures by molding a polyethylene resin specified in a melt index, a bending modulus, a Shore hardness and a degree of crystallinity. CONSTITUTION:A polyethylene resin (e.g. homopolyethylene resin or ethylene/ propylene copolymer resin) of a melt index of 4-60g/10min, a bending modulus >=4000g/cm<2>, a Shore hardness >=55D and a degree of crystallinity >=70% is molded by, e.g. injection molding to produce a cap 1 of a container 2 of a photographic film cartridge. The cap 1 can be produced inexpensively because the rate of crystallization of the above polyethylene resin is so high that the rigidity is high enough to suppress deformation or the like even in a shortened cooling time, and the molding cycle can be shortened. |
