| 摘要 |
PURPOSE:To obtain a sheet or a foamed board excellent in appearance through the use of a die lip produced by filling the microcracks in the chrome plated surface with resin powder and a thermoplastic resin, i.e., a specified polyester resin. CONSTITUTION:The thermoplastic polyester based resin foam is produced by extruding a mixture of a thermoplastic resin and a foaming agent, mixed while being fused in an extruder, through a gap 24 of a die lip 2 fixed to the forward end of the extruder to the low pressure region and foaming the mixture. The surface 21 of the die lip 2 touching a molten resin is subjected at first to chrome plating and roughened. The chrome plated surface is then heated and coasted with fine powder of cooled fluororesin thus obtaining the die tip 2 where microcracks in the chrome plated surface is filled with resin powder. A polyester resin produced through condensation of aromatic dicarboxylic acid and cliol is employed as the thermoplastic resin. |
