| 摘要 |
PURPOSE:To provide the subject film having a specific porous structure, exhibiting high elongation to prevent unexpected failure under practical stress, having excellent handleability and producible without difficulty. CONSTITUTION:An ultra-high-molecular weight polyethylene having a viscosity- average molecular weight of >=500,000 is dissolved in a good solvent to obtain a dope. A film produced by using the dope is immersed into a poor solvent to remove the good solvent from the film and the obtained porous film is drawn to obtain the objective film having a porous layer with a number of pores and two dense layers with a number of fine pores of a smaller pore diameter than the pore of the porous layer, wherein said dense layers are formed continuous to both faces of the porous layer. The film is used in the form of a laminated film produced by laminating two or more films. |
