| 摘要 |
1397721 Porous ionic membranes ALLIED CHEMICAL CORP 26 July 1972 [27 July 1971] 34992/72 Heading B5B [Also in Divisions C3 and B1-B2] A porous ionic membrane having a fixed charged is obtained by casting a solution having dissolved in it: (a) from 15 to 80% by weight of a matrix polymer, (b) from 10 to 80% by weight of a polyelectrolyte, and (c) at least 2À5% by weight of a cross-linking agent, all percentages being based on the combined weight of (a) + (b) + (c). After casting the film is dried at a temperature below the activation temperature of the cross-linking agent to remove at least a major portion of the casting solvent. The film is then cured by heating it to a high enough temperature to activate the cross-linking agent and so produce an insoluble membrane. In the examples the matrix polymer is polyvinylidene fluoride, polyvinylchloride-acrylonitrile copolymer, polyvinyl alcohol or polyvinyl butyral. The polyelectrolyte may be polystyrene sulphuric acid either free or as the sodium salt, polyvinylmethylimidazolium iodide or polyvinyl sulphonic acid. The cross-linking agent may be a mixture of a complex of BF 3 and monoethanolamine with either epoxide novolac resin or bisphenol-A- epoxide, or it may be trimethylol propane, formaldehyde or glutaraldehyde. Polyvinylmethyl ethyl-maleic anhydride and phenol-formaldehyde condensate serve as cross-linking agents and matrix polymers. Both a copolymer of maleic anhydride and vinyl sulphonic acid and a linear condensate of phenolsulphonic acid, phenol and formaldehyde can serve as polyelectrolyte and cross-linking agent. |
