PROCESS FOR PRODUCING POLYESTER RESIN FOAM AND POLYESTER RESIN FOAM SHEET

摘要

PURPOSE:To produce a foam having a high expansion ratio and homogeneous and fine cells without any coloring by adding an acid anhydride-containing compound to a thermoplastic polyester-based resin, melting the resultant blend, mixing the melt with a foaming agent and extruding the obtained mixture under conditions of a low pressure. CONSTITUTION:(B) A compound (preferably pyromellitic anhydride or benzophenonetetracarboxylic anhydride) having >=2 acid anhydride groups in the molecule in an amount of 0.05-5 pts.wt. is added to (A) 100 pts.wt. thermoplastic polyester-based resin [preferably polycyclohexane terephthalate, amorphous polyester, polyethylene terephthalate(PET) or polybutylene terephthalate(PBT)] and the resultant mixture is melted in an extruding expansion molding machine. A foaming agent (e.g. gaseous carbon dioxide or isopentane) is then injected into the melt and the obtained melt is subsequently extruded through a nozzle of the extruding expansion molding machine under conditions of a low pressure to afford a polyester resin-based foam having a high expansion ratio and homogeneous fine cells.