| 摘要 |
<p>PURPOSE:To form a polyester sheet adaptable for the production of various vessels from low viscosity polyester resin like polyester recovered or out of rank, by retaining the sheet within a specified intrinsic viscosity and subsequently extending it by a specified percent. CONSTITUTION:Recovered polyester resin as a raw material is fed in a melt extruder provided with a deaerator to melt it at 250-310 deg.C and dried continuously to reduce the water content to 50ppm. Next, the resin is extruded and cooled to form a sheet with the thickness of 125-1000mum by dies for molding sheets. Then the sheet is heated up to 60-180 deg.C by use of a heater or the like to form by a horizontal uniaxial stretching machine a uniaxial orientation polyester sheet which can stretch as much as 2.5-120% in the component crossing in right angles with the forward direction, preferably 20-50%, and have an intrinsic viscosity of 0.40-0.63. In this way, any draw down in not brought about, and it can be reused for the moldings of various kinds of food trays and industrial trays.</p> |
