A hollow vessel for heat sterilization, which is superior in the transparency and in the impact resistance with scarce odor, made of a polyolefin resin having characteristic properties comprising an underwater light transmittance of 70-99% resulting from determination of light transmission at a wave length of 450 nm for a resin specimen of a thickness of 0.5 mm which has been subjected to a heat sterilization treatment with steam at a temperature of 121.degree. C. for 20 minutes; a tensile elastic modulus of 200-700 MPa, determined according to ASTM D 638 for a resin specimen of a thickness of 0.5 mm which has been subjected to a heat sterilization treatment with steam; a haze value difference .DELTA. Haze of 1-20%, determined according to ASTM D 1330 for a resin specimen of a thickness of 0.5 mm respectively before and after a heat sterilization treatment thereof with steam; and a high-speed impact strength of 1.5-10 J, determined on an impact test at 0.degree. C. as the total rupture energy required for rupturing a resin specimen of 0.5 mm.times.9 cm.times.9 cm which has been subjected to a heat sterilization treatment with steam, wherein the impact test is carried out by settling the specimen on a jig having a hole of 1 inch diameter for receiving an impinging weight having an impact top of a diameter of 0.5 inch and causing the weight to impinge thereonto at an impingement speed of 3 m/sec.
Provided are a novel polypropylene resin composition, a gas permeable film comprising the same and provided with satisfactory optical characteristics (transparency, gloss and see throughness) as well as an excellent gas permeability (water vapor, oxygen and ethylene gas) without damaging a rigidity and a vegetable and fruit freshness long term-maintaining method using the above gas permeable film for a wrapping film. The polypropylene resin composition described above comprises 40 to 95% by weight of a propylene polymer (A) and 5 to 60% by weight of an ethylene/propylene/butene random copolymer (B) having a butene content of 3 to 40% by weight and an ethylene content of 10 to 30% by weight, wherein a ratio (.eta..sub.B /.eta..sub.A) of an intrinsic viscosity .eta..sub.B of the component (B) described above to an intrinsic viscosity .eta..sub.A of the component (A) described above falls in a range of 0.5 to 1.3; and the .eta..sub.B described above falls in a range of 0.5 to 3.0 dl/g. The gas permeable film described above is a single layer or multilayer film comprising at least one layer of a film of the polypropylene resin composition described above and having a thickness of 10 to 100 .mu.m, and it has the following characteristics: (1) a permeability T.sub.H2O of water vapor is 9 to 50 g/m.sup.2.multidot.24 h (based on JIS Z 0208), (2) a permeability T.sub.O2 of oxygen is 600 to 12500 nmol/m.sup.2.multidot.s.multidot.100 kPa (based on JIS K 7126-A) and (3) a permeability T.sub.ethylene of ethylene gas is 600 to 22500 nmol/m.sup.2.multidot.s.multidot.100 kPa (based on JIS K 7126-A).
