MEMBRANES MICROPOREUSES EN POLYETHERS PHENOLIQUES

摘要

1356758 Polyarylene polyether membranes KHONE-POULENO SA 20 July 1972 [21 July 1971] 34045/72 Heading B5B A polyarylene polyether membrane has, on each of its faces, pores of diameter between 0À1 and 25 Á, at least some of these pores passing through the entire thickness of the membrane. The polyarylene polyether may consist essentially of a plurality of units of the formula in which Q represents a phenyl radical, Q1 represents a phenyl radical, a phenyl radical substituted by up to 5 alkyl radicals with 1 to 8 carbon atoms, a biphenyl radical, a terphenylyl radical or a naphthyl radical, A represents a halogen atom and y, the value of which can vary from one unit to another, is equal to 0, 1, 2, 3 or 4. Q and Q1 may both represent a phenyl radical and y may be 0, or may have an average value between 0À5 and 2 in which case A represents a chlorine atom. The specific viscosity of the polyarylene polyether may be between 0À3 and 1À5, especially between 0À5 and 1, measured at 25‹ C. as a 5 g./l. solution in cyclohexanone. The membrane is made by (a) forming a solution of the polyarylene polyether with a solvent and a non-solvent for the polymer, the solvent and non-solvent being miscible with one another, (b) casting the solution on a temporary support, (c) leaving the polymer layer on the support in air for 1 second to 3 minutes, at a temperature of between 10‹ C. and the boiling point of the most volatile constituent of the solution, (d) immersing the polymer layer, still on its support, in a coagulation bath, and (e) separating the membrane from the support and drying it. Suitable solvents include cyclohexane, benzene, toluene, dichloromethane, dichloroethylene, trichloroethylene, tetrachloroethylene, chloroform, dichlorobenzene, monochlorobenzene, cyclohexanone, N-methyl-2-pyrrolidone, dimethyl formamide, dimethyl acetamide and tetrahydrofurane. Specified non-solvents include water, methanol, primary, secondary or tertiary butanol, acetone and methyl ethyl ketone, the non- solvent preferably amounting to between 8 and 15% by weight based on the weight of the solution. The coagulation bath may comprise methanol, ethanol, or an aqueous solution thereof. In examples, a polymer of the given formula is used, in which Q and Q1 represent a phenyl radical and y is zero; cyclohexanone-isbutanol mixtures are used as solvent, and methanol as coagulant. The object of treating with coagulating liquid is to gel the polymer solution or to complete any initial gel formation. This treatment is preferably carried out at room temperature. Depending on the shape of the support membranes of various shapes, e.g. planar, tubular and spiral, may be made. The membrane may also be reinforced by a woven, non-woven or knitted fabric of natural or synthetic fibres. Such membranes are prepared by casting on to the screen borne by the support. The membranes of the invention find application as separators in accumulators, for the degassing of aqueous solutions, and for carrying out gas exchanges with blood.