| 摘要 |
1295874 Porous fluoro-polymers E I DU PONT DE NEMOURS & CO 25 Nov 1969 [26 Nov 1968] 57715/69 Headings C3C and C3P [Also in Division B2] An object comprises a porous core of (1) fluorine-containing addition polymer, at least the surface of the core, and/or the pores at the surface of the core being coated or filled by (2) an addition copolymer in which substantially all of the recurring units contain fluorine atoms and some of the recurring units contain sulphonyl radicals, the molar proportion of the sulphonyl radicals in (2) being greater than the molar proportion of sulphonyl radicals (if any) in (1). The core may be polytetrafluoroethylene or may be a copolymer of tetrafluoroethylene with no more than 45% by weight of copolymerizable monomer, e.g. hexafluoropropylene or a sulphonyl-containing vinyl monomer. The core may be applicated by extrusion, casting or moulding to a sheet. The coating copolymer may contain units derived from vinyl fluoride, hexafluoropropylene, vinylidene fluoride, trifluorethylene, chlorotrifluoroethylene, a perfluoro (alkyl vinyl ether) and tetrafluoroethylene. The sulphonyl radicals may be SO 2 M (wherein M is F, Cl, OH or amine or OMe wherein Me is akyl metal or quaternary ammonium). The sulphonyl radical may be contained in repeating units of formula (wherein R f is a bifunctional perfluorinated radical containing 2-8 carbon atoms, S f is a sulphonyl radical). Preferably the vinyl radical is joined to the R group through an ether linkage. The preferred sulphonyl fluoride-containing copolymer is perfluoro-(3,6-dioxa-4-methyl-7- octenesulphonyl fluoride). The object can be produced by dipping the core in a dispersion or solution of the copolymer (2), removing the solvent for dispersing medium and optionally converting some or all of the sulphonyl groups of the coating copolymer into e.g. sulphonate or sulphonic acid groups. Alternatively polymer (1) may be mixed with up to 50% copolymer (2) and the mixture shaped, e.g. by fabrication, into sheeting. The pores of the core may be open. |
