| 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, outstanding in heat sealability and heat and impact resistances, suitable for thermoformed containers, by copolymerization, in the production of a polyester, of a third component and incorporation of a crystallization promoter. CONSTITUTION:A copolymerization is carried out between (A) ethylene terephthalate and (B) 2-10mol.% of a third component other than the component A, such as isophthalic acid or trimethylene glycol followed by incorporation of (C) a crystallization promoter (e.g. magnesium silicate, sodium montanate). Thence, the resultant copolymer is extruded through e.g. a slit die and quenched, thus obtaining the objective polyester sheet with a density o <=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. |
