| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for producing an unsaturated polyester resin (hereinafter abbreviated to polyester resin) using a recovered polyethylene terephthalate (hereinafter abbreviated to R-PET) as a raw material, more precisely a method for producing a polyester resin using an R-PET having a prescribed metal content. SOLUTION: In this method for producing an unsaturated polyester resin by sub jecting a polyethylene terephthalate to glycol decomposition and carrying out polycondensation by adding anα,β-unsaturated polybasic acid or its acid anhydride, a recovered polyethylene terephthalate having <=1,000 ppm of total content of heavy metals selected from zirconium, vanadium, chromium, molybdenum, manganese, iron, nickel, lead, tin and copper is used. Since a polyester resin having shelf stability and curability can be obtained from an R-PET as a raw material, a preferable raw material for a molding material can be obtained at an extremely low cost.</p> |
