| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyester useful for a container for packing a food and a beverage, etc., capable of reducing the formation of a cyclic oligomer in melting and showing specific qualities, by mixing a polyester containing a condensation polymerization catalyst with a specific phosphorus compound after solid-phase polymerization. SOLUTION: This polyester consists essentially of a polyethylene terephthalate containing (A) Sb, Ti or Ge and (B) an OH-containing phosphorus compound derived from phosphoric acid such as orthophosphoric acid, a (poly) metaphosphoric acid, a polyphosphoric acid of the formula Hn+2 Pn O3n+1 ((n)>=2) and their salts or esters and is regulated to have a cyclic oligomer content after melting at 280 deg.C for 5 minutes lower than that of the same polyester containing only the component A. The polyester is obtained by carrying out melt condensation polymerization using 1×10<-6> to 1×10<-2> mol based on 1mol of the total acid component (Z) of the component A and then solid-phase polymerization to give a polyester and mixing the polymer with the component B in an amount corresponding to 1×10<-6> to 1×10<-2> mol based on 1mol of Z.
|
