| 摘要 |
PROBLEM TO BE SOLVED: To obtain a separator suitable for an alkali secondary cell capable of making an electric cell have a large capacity by making a a nonwoven cloth comprising an ethylene.α-olefin copolymer hydrophilic by a method of a radiation graft polymerization, a plasma graft polymerization, etc. SOLUTION: This olefinic nonwoven cloth is obtained by melt blowing an ethylene.α-olefin copolymer obtained from a copolymerization of ethylene with an α-olefin such as 1-octene and having 0.7-7 mol.%, preferably 0.2-3 mol.% of α-olefin content to obtain a melt blown nonwoven cloth having 1-10 μm, preferably 2-7 μm average fiber diameter and >=0.6 kg/m<2> , preferably >=0.6 kg/5 cm<2> nonwoven cloth strength. The resultant nonwoven cloth is dipped in a mixed solution of acrylic acid with methacrylic acid and treating with a radiation induced graft polymerization or a plasma graft polymerization to impart hydrophilicity of >=250% liquid holding fraction. |
