PRODUCTION OF CRYSTALLINE UNSATURATED POLYESTER RESIN

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a crystalline unsaturated polyester resin useful as a raw material for a molding material using a recycled polyethylene terephthalate (hereinafter abbreviated to R-PET). SOLUTION: A recovered polyethylene terephthalate having >=0.1 wt.% and <=10 wt.% water content is subjected to glycol decomposition and polycondensation is carried out by adding anα,β-unsaturated polybasic acid or its acid anhydride to give an unsaturated polyester resin. The unsaturated polyester resin is dissolved in a polymerizable monomer, cooled and solidified. Since the unsaturated polyester resin obtained from the recovered polyethylene terephthalate as a raw material is solidified at normal temperature while containing the monomer, a raw material for a suitable molding material can be obtained at an extremely low cost.