| 摘要 |
PURPOSE:To provide high strength while protruding an adequate rupture ductility and pore diameter by having a three-dimensional mesh structure, containing a polyethy lene of a predetermined super high molecular weight, and selecting a porosity, a permea bility, and a rupture ductility, etc., of a predetermined value, respectively. CONSTITUTION:A micro porous film containing a polyethylene of a super high molecular weight has a three-dimensional mesh structure, and a super high molecular weight polyethylene of at least 2 million in a viscosity average molecular weight is contained by at least 30wt.% of the micro porous film. The micro porous film is designed to have a porosity of not less than 40%, a permeability of not above 450sec/100cc, an elasticity in a mechanical direction of not less than 4000kg/cm<2>, a rupture ductility both in the mechanical direction and in the perpendicular direction of not less than 400%, a bubble point in an ethyl alcohol of 2 to 10kg/cm<2>, and the ratio of a maximum pore diameter to an average pore diameter of not less than 1.6. Whereby, a micro porous film can be provided such that it has an adequate elongation in its width direction while having high strength in the mechanical direction, and furthermore has an adequate pore diameter while being homogeneous. |
