| 摘要 |
PURPOSE:To improve efficiently the fine moldability of mechanically ground polyethylene (hereafter called PE) by conducting rotational molding of PE powder mixture having a specific angle of repose. CONSTITUTION:Rotational molding is performed by using PE powder mixture with angles of repose 33-39 deg. and bulk specific gravities 0.33-0.40g/cc obtained by kneading 80-20wt% by weight mechanically ground PE that contains 80wt% or more by weight particles with diameters 150-500mum and has angles of repose 40 deg. or more obtained when pellet shaped PE is ground mechanically, and 20-80wt% by weight spherical powder PE that contains 70wt% or more by weight particles with diameters 150-300mum and has angles of repose 36 deg. or less. Thus, it is possible to solve problems such as difficult fine moldability, difficulty of design in molding surface decorations and products of irregular thickness, necessity of exact control for molding conditions, false reproducibility for molding dies, occurrence of pin holes, cavities, etc., which all are found in raw powder PE for conventional rotation molding. |
