| abstract |
The present invention provides a biodegradable expanded material having excellent expandability, moldability, impact resistance, heat resistance and storage stability. The present invention also provides a process for the preparation of the foregoing expanded material. The present invention further provides a laminate of a non-expanded material layer and an expanded material layer prepared from the foregoing expanded material which exhibits excellent impact resistance and heat resistance and an excellent transparency in the non-expanded material even after heat treatment so that a pattern printed on the inner side of the non-expanded material layer can be clearly viewed from the outside. A novel expanded material is provided made of a hydroxycarboxylic acid based polyester having a weight-average molecular weight of from 20,000 to 400,000 comprising as structural units a structural unit derived from hydroxycarboxylic acid, a structural unit derived from molecular weight increasing agent and/or a structural unit derived from polymerization catalyst deactivator. |