| 摘要 |
PROBLEM TO BE SOLVED: To effectively suppress the self-discharge and provide excellent cycle life performance by using a polyolefin fiber subjected to a hydrophilic treatment by introducing a hydroxyl group and a carbonyl group by fluorine gas and a hydrophilic treatment by graft polymerizing an acrylic acid. SOLUTION: In a nonwoven fabric consisting of a polyolefin fiber, the polyolefin fiber is made hydrophilic by providing at least a hydroxyl group, a carbonyl group and an acrylic acid on the surface. In this case, the hydrophilic treatment of the polyolefin fiber is performed by leaving the polyolefin fiber in a 1:1 mixed gas of fluorine gas and oxygen gas for several tens minutes under ordinary temperature and normal pressure condition to introduce the hydroxyl group and the carbonyl group. The nonwoven fabric consisting of the polyolefin fiber made hydrophilic by fluorine gas is dipped in a mixed solution consisting of the acrylic acid as vinyl monomer, and the acrylic acid is graft polymerized by irradiating with ultraviolet ray for several minutes. |
