| 摘要 |
A pervious cellulosic material is impregnated with an aqueous solution of polyvinyl alcohol containing a water-soluble and oxidation resistant plasticiser and a water-soluble cross-condensation agent and then dried. A cross-condensation agent is defined as an ester of an aliphatic dibasic acid containing 4 to 14 carbon atoms within the acid radical. The pervious cellulosic material may be permeable or semi-permeable and may consist of regenerated cellulose, cellulose hydrates, ethers, esters, mixed esters and ethers, substituted esters or sheets of woven or felted cellulosic fibres, e.g. paper or cotton felt. The aqueous solution may be applied to the pervious cellulosic material by spraying, dipping, calendering or brushing and drying may be accomplished by exposure to air or may be accelerated by the application of heat from radiant or conductive sources. Specified plasticizers are di- and tri-hydroxy alcohols, e.g. diethylene glycol and glycerol, which have previously been subjected to oxidation, e.g. by treatment with H2O2, KMnO4 or hot air, propylene glycol and water-soluble polyethylene glycols. Specified cross-condensation agents are diethyl glutarate and dibutyl sebacate. The aqueous polyvinyl alcohol may be derived from at least 50% hydrolized polyvinyl acetate. Examples are given. The products are useful as diaphragms in electrolytic systems. |
