To provide a porous polypropylene film having interconnected through- holes and excellent air permeability, a method for the production of the film and an absorbing material having excellent air-permeability, moisture- permeability, feeling, strength and leak-proof property.
The objective porous film is composed of a resin composition containing (I) a resin selected from (i) a propylene-ethylene copolymer having an ethylene content of 3.0-7.0 wt.% and an MFR of 2.0-4.0 g/10 min measured at 230°C and (ii) a polypropylene resin mixture containing the propylene-ethylene copolymer and (II) a β-crystal nucleation agent. The film has a porosity of 20-80%, a Gurley air-permeability of ≤5,000 sec/100 cc measured in conformity with JIS P-8117, a moisture permeability of ≥2,000 g/m2.24 h measured in conformity with JIS Z-0208 and a water pressure resistance of ≥75 kPa measured in conformity with JIS L-1092 using an aqueous solution of a surfactant. The absorbing material is produced by using the film as the back sheet.
SADAMITSU KIYOSHI
HOGI MANABU
OSADA KENICHIRO
KOBAYASHI TOSHIAKI
