| abstract |
Provided is a porous film which is excellent in a tearnstrength and has a low heat shrinkage. Such film is produced bynsubjecting to heat treatment on specific conditions, a porous filmncomprising a resin composition comprising:n (a) a polypropylene base resin blend comprising 100 parts bynweight of an ethylene-propylene block copolymer having anmaximum peak temperature (Tm) of 140°C ≤ Tm ≤ 165°Cnwhich is given by differential scanning calorimetry (DSC), 3nto 40 parts by weight of low density polyethylene and 3 to 40nparts by weight of an ethylene-vinyl acetate copolymer, (b) calcium carbonate, (c) titanium oxide coated on a surface thereof with silica and/ornalumina, (d) a hindered amine light stabilizer having a molecular weightnof 1500 to 4500, (e) an ethyl ester phosphorous acid or biphenylene phosphonitenantioxidant, and (f) a hindered phenol antioxidant, nwherein the above resin composition comprises 100 to 200 parts bynweight of (b), 0.5 to 20 parts by weight of (c), 0.2 to 10 parts by weightnof (d), 0.03 to 3 parts by weight of (e) and 0.05 to 3 parts by weight ofn(f) each per 100 parts by weight of (a). A laminate sheet comprisingnthis polypropylene base porous film and a polyolefin base nonwovennfabric is excellent in a moisture permeability, a weatherability and anheat resistance. |