| 摘要 |
1484612 Laminates E I DU PONT DE NEMOURS & CO 20 May 1975 [21 June 1974] 21578/75 Heading B5N [Also in Division C7] A composite ion-exchange polymer film comprises pendant sulphonyl groups in ionexchangeable form, each attached to a C atom to which at least one F atom is also attached, not more than 1/3 of the thickness thereof comprising polymer (i) which has an EW at least 250 greater than polymer (ii) comprising the remainder of the film. The film is used with polymer (i) facing the cathode in conventional diaphragmcell chlor-alkali production. Polymer (i) may have an EW no more than 2000 and polymer (ii) an EW of 1000-1500. The membrane may comprise a copolymer of an ethylenically unsaturated fluorocarbon, e.g. TFE with an unsaturated fluoro-sulphonyl compound of formula CF 2 =CFORfSO 2 F where the ether link is optional and Rf is a bivalent C 2-8 perfluoro radical with or without ether linkages, e.g. CF 2 = CFOCF 2 CF(CF 3 )OCF 2 CF 2 SO 2 F, and wherein the SO 2 F groups are subsequently converted to ion-exchange form such as a sulphonamide or sulphonic acid or salt group. The ion-exchange groups of polymers (i) and (ii) may be the same or different. A reinforcement of fabric of fluorinated resin, glass or quartz may be embedded in the polymer (ii). A laminate with a PTFE cloth is disclosed. |
