Resin composition capable of exhibiting high melt viscoelasticity, aromatic polyester resin foamed body produced therefrom and process for producing the foamed body

A process for producing an aromatic polyester resin foamed body, characterized by melting a resin composition capable of exhibiting a high melt viscoelasticity comprising 100 parts by weight of an aromatic copolyester resin which contains a branching component unit having at least three ester-forming groups in the ratio of 0.01 to 5 moles per 100 moles in total of aromatic dicarboxylic acid units and which has a limiting viscosity of 0.4 to 1.0 dl/g, and 0.05 to 5 part by weight of a compound having at least two acid anhydride groups in its molecule, thereafter mixing the resulting melt with a blowing agent, then extruding the resulting mixture into a low pressure zone and foaming the mixture.

An aromatic polyester resin foamed body having a density of at most 0.3 g/cm.sup.3, which is obtained by melting a resin composition capable of exhibiting a high melt viscoelasticity comprising 100 parts by weight of an aromatic copolyester resin which contains a branching component unit having at least three ester-forming groups in the ratio of 0.01 to 5 moles per 100 moles in total of aromatic dicarboxylic acid units and which has a limiting viscosity of 0.4 to 1.0 dl/g, and 0.05 to 5 parts by weight of a compound having at least two acid anhydride groups in its molecule, thereafter mixing the resulting melt with a blowing agent, then extruding the resulting mixture into a low pressure zone and foaming the mixture.