| 摘要 |
PURPOSE:To reduce the discoloration of a molded product by applying ultraviolet irradiation treatment to a polypropylene molded product to which a phosphorus type oxidation inhibitor is added and subsequently heat-treating the same at specific treatment temp. within a specific treatment time range. CONSTITUTION:PP used in a sheet, a film, an injection molded product, a hollow molded product or a profile extrusion molded product is a homopolymer of PP, a copolymer of PP and alpha-olefin other than PP or a graft copolymer of acrylic acid or maleic anhydride and said homopolymer or copolymer and, as a phosphorus type oxidation inhibitor, 2,2-methylene bis(4,6-di-t-butylphenyl) octyl phosphite is used. The treatment temp. (A: unit deg.C) at the time of heat treatment performed after ultraviolet irradiation treatment is 80-450 deg.C and, when said temp. is lower than 80 deg.C, the reducing effect of discoloration is not almost obtained and, when the temp. exceeds 450 deg.C, the deformation and deterioration of the molded product are generated. A treatment time (B: unit sec) is set to 100<=Bsq. rt. A<=300 in the relation to temp. and, when said time is below 100/sq. rt. A sec, discoloration reducing effect is not developed and, when the time exceeds 300/sq. rt. A sec, the deformation of deterioration of the molded product is generated. |
