| 摘要 |
PURPOSE:To obtain a fine porous film having small hole-diameter and moreover large porosity by using a specified synthetic resin particles. CONSTITUTION:This porous film is composed of polyolefin and the synthetic resin particle which is dispersed in the polyolefin and has the softening temperature or decomposing temperature higher than the forming temperature of the polyolefin, and average particle diameter of 0.01-5mum. The film has the network composed of the communication hole having the maximum diameter of the small hole of at most 5mum, and it has the porosity of 30-98% and is molecularly orientated by drawing. When the average diameter of the synthetic resin particle is out of the range of 0.01-5mum, the fine porosity is not able to be obtained or only the porous film with large diameter of maximum fine hole is obtained. When the particle diameter distribution of the synthetic resin particle is in the narrower range, the more uniform fine holes may be obtained. The compounding amount of the synthetic resin particle is preferably in the range of 20-80wt.% of the total amount of polyolefin and synthetic resin. |
