Abstract: The invention provides a method for producing a foamed article comprising the steps of: heating a mixture comprising (a) 100 parts by weight of linear saturated polyester, (b) 0.1 to 10 parts by weight of a mixture as a coupling agent of 0 to 100% by weight of a compound having two epoxy groups in the molecule, and 100 to 0% by weight of a compound having two or more epoxy groups, and (c) 0.01 to 5 parts by weight of a metal salt of a carboxylic acid as a coupling reaction catalyst, at a temperature of a melting point of the polyester or more to provide a melt flow rate of 50 g/10 minutes or less and swell of 10 to 200%, whereby a polyester resin is formed; and heating and foaming the polyester resin using a foaming agent .

Abstract: A method for producing a high molecular weight polyester having swell of 1-200 percent is described. In the method, a mixture consisting of (a) 100 parts by weight of a linear saturated polyester; (b) 0.3˜10 parts by weight of a mixture, as a coupling agent, which is composed of (1) 0-100 percent by weight of a bifunctional epoxide ingredient containing 2 epoxide groups per molecule and (2) 100-0 percent by weight of a polyfunctional epoxide ingredient containing 3 and more epoxide groups per molecule; and (c) 0.01˜5 parts by weight of metal salt of carboxylic acid as a catalyst for coupling reaction, is heated at a temperature higher than a melting point of said polyester resin.

Abstract: A method for producing a high molecular weight polyester having swell of 1-200 percent is described. In the method, a mixture consisting of (a) 100 parts by weight of a linear saturated polyester; (b) 0.3˜10 parts by weight of a mixture, as a coupling agent, which is composed of (1) 0-100 percent by weight of a bifunctional epoxide ingredient containing 2 epoxide groups per molecule and (2) 100-0 percent by weight of a polyfunctional epoxide ingredient containing 3 and more epoxide groups per molecule; and (c) 0.01˜5 parts by weight of metal salt of carboxylic acid as a catalyst for coupling reaction, is heated at a temperature higher than a melting point of said polyester resin.