| 摘要 |
PROBLEM TO BE SOLVED: To provide a separator for secondary battery, having superior durabil ity by applying a high grade hydrophilic processing to a material, having an inner structure such as a cloth or a material having high hydrophobic property, such as polyolefin. SOLUTION: This hydrophobic processing method comprises arranging of a pair of opposing electrodes 2 and 3 with the opposing surface of one or both of the electrodes covered with a solid dielectric substance, nearly at the atmospheric pressure in a mixture gas atmosphere of oxygen gas and sulphur dioxide gas (or an inert gas) or in a mixture gas atmosphere of inert gas, oxygen gas and sulphur dioxide gas, a placing an object to be processed (for example, a nonwoven cloth of polypropylene) F between the electrodes and solid dielectric substance or between the pieces of dielectric substance generating plasma discharge by impressing an electric field between the electrodes 2 and 3, and imparting a hydrophilic property to the object F.
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