| 摘要 |
PROBLEM TO BE SOLVED: To improve the productivity of a blow-molded article having flexibility and rigidity by a method wherein specified polypropylene resin having flexibility is employed at the flexible structural part of an air duct or a joint part. SOLUTION: A material employing at a flexible part is a block copolymer, in which the copolymer component of ethylene-propylene follows to the homopolymer component of propylene. When the limiting viscosity of the homopolymer component is denoted by [η]PP, that of the copolymer component by [η]RC, the weight of the homopolymer component by WPP and that of the copolymer component by WRC, the product of the ratio of the limiting viscosities of the copolymer component and of the homopolymer component and the ratio of the weights of the homopolymer and of the copolymer: [([η]RC/[η]PP)×(WPP /WRC)] lies in the range of 0.2-2.0. Further, the ratio of the MFR (230 deg.C; 21.18N) of the homopolymer component to that of the copolymer comp component lies in the range of 0.3-4.0. |
