| 摘要 |
FIELD: chemistry.SUBSTANCE: invention relates to a polypropylene-based heterophase composition and to the use of said composition to make pipes operating under pressure. The composition contains A) 80-97 wt % random propylene copolymer containing 0.1-4 wt % 1-hexene-derived links and B) 3-20 wt % propylene and ethylene copolymer having content of ethylene-derived links of 50-55 wt %, except limiting values. The composition has a melt flow index of 0.5-5 g/10 min, measured according to ISO 1133 (230°C, 5 kg), and characteristic viscosity (IV) of a xylene-soluble fraction at room temperature of 2.5-5.5 dl/g. The obtained heterophase composition has an improved balance of properties between hardness, which is shown by bending modulus values and tensile properties, and crack resistance under the effect of the environment.EFFECT: pipes made from said heterophase polyolefin composition exhibit very good creep and opacity properties.8 cl, 4 tbl, 4 ex |
