| 摘要 |
PURPOSE:To obtain a uniform foam of a high-melting heat-resistant resin such as a thermoplastic resin, by mixing the heat-resistant resin with an alkali metal oxalate and melt-processing the mixture. CONSTITUTION:A heat-resistant resin is mixed with an alkali metal oxalate, and the obtained mixture is melt-processed to obtain the purpose resin foam. The thermoplastic resin used is a heat-resistant resin which is a high-melting thermoplatic resin and has a resin melting temperature of 330-450 deg.C. Examples of these resins include polyoxybenzoyl, its copolymers and polyether ether ketone. This foam can be obtained by adding a blowing agent to such a resin during its molding and melt-processing the mixture. Examples of the blowing agents used include alkali metal oxalates, especially, sodium and potassium salts. When the melting temperature of the resin is below 350 deg.C, said oxalate can not be decomposed during processing, and when that of the resin is above 450 deg.C, the salt decomposes before the resin is molten. Therefore, no foam can be obtained in these cases.
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