| 摘要 |
PURPOSE:To obtain a vinyl chloride sheet wherein strains do not occur at various postformings of a thermoplastic resin in blow molding, vacuum molding, and pressure molding by pretreating calender sheets, whose outer layers and core layers are respectively formed at a specified draw ratio, at specified material temperature and face pressure singularly. CONSTITUTION:An outer layer A and a core layer C are set between a velocity ratio (draw ratio) 1.10-1.30 of a linear velocity of a calender roll and a linear velocity of a take-off roll so as to manufacture calender sheets for pressing. Next, these sheets are respectively pressed by high temperature and low pressure of a material temperature 170-175 deg.C and a face pressure 20kgf/cm<2> singularly, cooled gradually, and annealed. When the material temperature at heating the calender sheets exceeds 175 deg.C, a vinyl chloride resin is deteriorated by the heat. When the material temperature is under 170 deg.C, delustering occurs due to the heat when a semicircle of a globe is to be molded after the calender sheets are layered. When the face pressure exceeds 30kgf/cm<2>, the calender sheets flow, so that strains generate in the sheets. When the face pressure is under 10kgf/cm<2>, pockmarks generate. |
