| 摘要 |
PURPOSE:To form a hydrophilic membrane on the surfaces of a membrane and micropores thereof, which is durable so that it does not drop out of said surfaces even when water is filtered therethrough, by melting a hydrophilicity-imparting agent, which is a solid at room temp. and substantially insoluble in water, by heating and depositing it on a hydrophobic porous hollow yarn membrane. CONSTITUTION:Preferred examples of the above hydrophilicity imparting agents which can be thermally molten and are a solid at room temp. and substantially insoluble in water (solubility in water at the working temp. of the membrane being 30ppm or below), are 2-22C higher fatty acid (e.g. lauric, myristic, palmitic or stearic acid) monoesters of propylene glycol. Examples of said hydrophobic porous membranes are those composed of polyethylene, polypropylene, polyvinylidene fluoride and polytetrafluoroethylene. In the continuous treatment of the hydrophobic porous hollow yarn membrane to make it hydrophilic, the yarn membrane 2 is drawn out of a delivery bobbin 1 and wound around a wind-up bobbin 2, while it is brought into contact with a heated mirror roll 3 on which is formed a thin liquid film of the hydrophilicity imparting agent which is heated in a tank 5 provided with a heating means and converted into liquid.
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