| 摘要 |
Dry, finely divided and flowable polyethylene powders are made by dissolving polyethylene at elevated temperatures in a mixture of a solvent and a non-solvent therefore, the non-solvent having a higher boiling point than the solvent and being miscible therewith, at least in the proportions in which it is used, distilling of the solvent and non-solvent and at the same time continuously breaking up and circulating the liquid-containing solid polyethylene mass which forms. Solvents specified are carbon tetrachloride, trichloroethylene, perchloroethylene, benzene, toluene and xylene. Non-solvents specified are butanol, the methyl, ethyl, propyl and butyl half-ethers of glycol, methyl isobutyl ketone, dibutyl ether and aliphatic paraffin hydrocarbons. The process may be applied to mixtures of polyethylene with other polymers, e.g. polyisobutylene, polybutadiene, polyisoprene, butadiene-acrylonitrile copolymers, natural rubber and chlorinated rubber. In addition, mixtures of polyethylenes of differing molecular weights may be jointly processed. The polyethylene and the added polymer may be mixed either before or after being dissolved in the mixture of solvent and non-solvent. |
