| 摘要 |
PURPOSE:To obtain foam of good quality having uniform and fine foams by a method wherein a mixture of a fine powder of a polytetrafluoroethylene resin with specific viscosity and a thermoplastic polyester resin is melted within an extruder and nitrogen is injected into the molten mixture under pressure to extrude a foamable compsn. CONSTITUTION:A mixture of 0.02-0.5 pts.wt. of a fine powder of a polytetrafluoroethylene resin having viscosity such that the resin flows out of a hole with an inner diameter of 2.1mm and a length of 8.0mm in an amount 1.0g/10min or more at 340 deg.C under pressure of 20kg/cm<2> and 100 pts.wt. of a thermoplastic polyester resin is introduced into an extruder to be melted and nitrogen is injected into the mixture to form a foamable compsn. which is, in turn, extruded from the cap provided to the leading end of the extruder to be foamed. The thermoplastic polyester resin is high mol.wt. chain polyester obtained by esterifying aromatic dicarboxylic acid with dihydric alcohol. Since this thermoplastic polyester resin is used, tough foam having good heat resistance is obtained. |
