| 摘要 |
PROBLEM TO BE SOLVED: To obtain a foam having uniform and fine cells continuously and stably by melting a composition comprising a polyester resin comprising a polyethylene terephthalate resin and a polybasic carboxylic acid and an oxazoline-group-containing compound, adding a blowing agent to the melt and extruding the melt into a low-pressure zone to expansion-mold it. SOLUTION: Desirably the number-average molecular weight of the polyethylene terephthalate resin is 10,000-50,000, and its intrinsic viscosity is 0.5-1.1 dl/g. The polycarboxylic acid used is desirably one having at least three carboxyl groups in the molecule and having a molecular weight of 150-350 and is exemplified by trimellitic acid. The compound having at least two oxazoline groups (e.g. a condensate of a polycarboxylic acid with 2- aminoalcohol) is used in an amount of 0.1-10 pts.wt. per 100 pts.wt. polyester resin (having a number-average molecular weight of 3,000-40,000). The blowing agent used is exemplified by a liquid volatile one (e.g. butane). |
