| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyester film satisfactory in both flame retardancy and heat shrinkability by using a polyester resin prepared by the copolymerization of terephthalic acid and ethylene glycol as the principal components, other acid components, other glycol components and a carboxyphosphinic acid derivative. SOLUTION: A polyester resin is obtained by the copolymerization of terephthalic acid and ethylene glycol as the principal components, 3-50 mol%, in total, acid components other than terephthalic acid glycol components other than ethylene glycol and 0.05-2 wt.% (in terms of the phosphorus atoms) flame retardant represented by the formula (wherein R1 is a 1-20C divalent hydrocarbon group; R2 is a 1-10C monovalent hydrocarbon group; and R3 and R4 are each an ester-bond-forming functional group). This resin is optionally mixed with suitable amounts of various additives, the mixture is dried and molded into a film, and the film is stretched and heat-treated to obtain a flame-retardant heat-shrinkable polyester film having a thickness of 1-60μm and a shrinkage of 10-70% in at least one direction as measured by immersion in water at 80 deg.C for 1 min.
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