| 摘要 |
PURPOSE:To obtain the title sheet having each specified density and the differ ence between the crystallization peak temperatures in the temperature rise and fall measured by a differential calorimeter, suitable for thermoformed containers, by blending polyethylene terephthalate, polybutylene terephthalate and crystallization nucleating agent. CONSTITUTION:A composition is prepared by blending (A) 100pts.wt. of a polyester constituted chiefly of ethylene terephthalate recurring unit, (B) 5-30pts.wt. of a second polyester constituted chiefly of butylene terephthalate recurring unit, and (C) pref. 0.1-2wt.% based on the component A, of a crystallization nucleating agent (e.g. magnesium silicate) followed by extruding the resultant blend through e.g. a slit die and quenching, thus obtaining the objective polyester sheet with a density of <=1.34g/cm<3> and the difference between the crystallization peak temperatures in the temperature rise and fall measured by a differential calorimeter being 40-80 deg.C. |
