METHOD FOR PREPARING HIGHLY TRANSPARENT POLYESTER SHEET HAVING IMPROVED HEAT RESISTANCE

摘要

PURPOSE: A method for preparing a polyester sheet that presents excellent release property, good transparency and markedly improved heat resistance is provided. CONSTITUTION: A method for preparing a highly transparent polyester sheet having improved heat resistance according to the present invention comprises the steps: a) melting, extruding and cooling polyethylene naphthalate resin having limit viscosity of 0.4 to 1.0 dl/g and glass transition point(Tg) of 110 to 120 degees celsius wherein the main repeating unit of the resin contains at least 60 parts by weight of ethylene naphthalate to form a sheet; and b) applying water-soluble coating solution that contains colloidal alumina, water soluble polyester resin, water soluble polyurethane resin and water soluble acryl emulsion on at least one surface of the said formed sheet.