| 摘要 |
PURPOSE:To obtain a porous film having excellent drawability and vent holes, by blending a polyolefin based polymer with a thermoplastic polyester polymer using specific heating and kneading condition, forming a film and drawing the obtained film. CONSTITUTION:A polymer blend consisting of (A) 100pts.wt. polyolefin based polymer, (B) 0-50pts.wt. polyester polyether type thermoplastic elastomer and (C) a particulate thermoplastic polyester polymer having <=0.5 intrinsic viscosity in an amount of 25-90pts.wt. based on 100pts.wt. total amount of the components (A) and (B) is heated and melted in an extruder above the melting point of the component (C) at >=200/sec shearing rate while being cooled so as to provide a temperature range below the crystallization temperature of the component (C) and above the melting point of the component (A), cooled below the crystallization temperature of the component (C), formed into a film above the melting point of the component (A) and quenched to provide an undrawn film, which is then drawn to afford the aimed film having pores with 0.1-100mu average pore diameter, >=200g/m<2>.24hr moisture permeability and >=80cmAq water resistant pressure. |
