| 摘要 |
PROBLEM TO BE SOLVED: To obtain a copolymer which is excellent in impact resistance and in the balance between low-temp. heat sealability and rigidity by specifying the stereoregularity index, compsn., and physical properties of a random copoly mer of propylene, ethylene and 1-butane. SOLUTION: This copolymer has a stereoregularity index P obtd. by using the formula (wherein I, Im, Tδδand Sαγare the signal strengths 19.8-22.2, 21.4-22.2, 33.3 and 38.0 ppm, respectively) from a spectrum measured with<13> C-NMR of 85 mol. % or higher and satisfies the following conditions: the content (αmol %) of ethylene units and that (βmol. %) of 1-butane units satisfy the formula: 0.1<=α+β<4; the MI is 1-12 g/10 min; the boiling diethyl ether extract E andα+βsatisfy the formula: E<=0.2(α+β)+0.6; the m.p. Tm ( deg.C) obtd. with a differential scanning calorimeter andα+βsatisfy the formula; Tm <=164-3.6(α+β); and the MI and the relaxation timeτobtd. by the frequency dispersion measurement at a frequencyω#0 of 10<0> red/sec satisfy the formula:τ<=0.65-0.025MI. |
