| 摘要 |
PURPOSE:To improve the transparency, color tone and thermal properties of a polyester and at the same time to increase its mass productivity, by depolymerizing an ester oligomer or prepolymer with a small amount of water, adding a sulfur acid compound and polycondensing the product. CONSTITUTION:An ester oligomer or prepolymer of an intrinsic viscosity of 0.06-0.40, obtained by polycondensing bis(beta-hydroxyethyl) terephthalate or its low polymer is depolymerized with 1X10<-4>-500X10<-4>mol, per mol of the acid component of polyester, water, and a sulfur acid compound is added in an amount of 0.1X10<-4>-100X10<-4> equivalent, per mol of the acid component of polyester. The product is polycondensed in vacuum. Examples of said sulfur acid compounds include sulfuric acid, its esters, aliphatic sulfonic acids, and derivatives thereof, aromatic sulfonic acids and derivatives thereof.
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