| 摘要 |
Thermoplastic material, e.g. polyvinyl chloride, polystyrene or polymethacrylic acid ester, containing a non-solvent blowing agent, is obtained by treating the material simultaneously or successively with a solvent blowing agent and the non solvent blowing agent at a temperature lower than the B.P. of either agent and subsequently washing out the solvent blowing agent until less than 2% by weight, relative to the material, remains. The material contains 5-15% by weight of non-solvent blowing agent and is expanded by heating, e.g. at 75 DEG -100 DEG C. Suitable non-solvent blowing agents are butane, pentane, hexane, petroleum ether and their mixtures, whilst solvent blowing agents are low molecular esters, ethers, ketones and chlorinated aliphatic hydrocarbons, examples being given.ALSO:Thermoplastic material containing a non solvent blowing agent, is obtained by treating the material simultaneously or successively with a solvent blowing agent and the non-solvent blowing agent at a temperature lower than the B.P. of either blowing agent and subsequently washing out the solvent blowing agent until less than 2% by weight, relative to the material, remains. The material contains 5-15% by weight of non-solvent blowing agent. Materials specified are polystyrene, polymethacrylic acid ester, and polyvinyl chloride. Suitable non-solvent blowing agents are butane, pentane, hexane, petroleum ether and their mixtures, whilst solvent blowing agents are low molecular esters, ethers, ketones and chlorinated aliphatic hydrocarbons, examples being given. Heating e.g. at 75-100 DEG C. gives a cellular product.
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