METHOD FOR BLOW MOLDING OF POLYPROPYLENE

摘要

PURPOSE:To obtain a molded product excellent in transparency by a method wherein a heater is provided to the mandrel and/or the core of a blow molding die and the temp. of the core is kept higher than that of an outer die to carry out the blow molding of polypropylene. CONSTITUTION:A heater 5 is provided to the mandrel 1 and/or the core of a blow molding die to heat the same and the temp. of the core 2 is kept higher than that of an outer die 3 to carry out the blow molding of polypropylene. The temp. of the core 2 is pref. kept 5-100 deg.C higher than that of the outer die 3. By this method, a molded product excellent in transparency is obtained and the draw-down property of a parison during blow molding is improved and the molded product with reduced deviation of a wall thickness is obtained.