| abstract |
A novel propylene elastomer having such characteristics that: (1) it is composed of 50-95 mole % of units derived from propylene and 50-5 mole % of units derived from 1-butene, (2) it has a triad tracticity (mm faction) of at least 90 % as determined by 13C-NMR spectrometry (in hexachlorobutadiene using tetramethylsilane as the internal standard), (3) it has a limiting viscosity of 0.1-12 dl/g (at 135 °C in decalin), (4) it has a molecular weight distribution (Mw/Mn) of 3 or less, and (5) it has a randomness parameter (B) of 1.0 to 1.5, preferably 1.0 to 1.3. In addition, it is desirable that: (6) it has a melting point (Tm) of 60-140 °C and the following relationship holds between the Tm and the 1-butene unit content (M, mole %): -2.6 M + 130 « Tm « -2.3 M + 155, (7) the following relationship holds between the degree of crystallinity (C) and the 1-butene unit content (M, mole %) C » -1.5 M + 75, the elastomer is excellent in rigidity, heat and scratch resistances, transparency, heat sealability, and blocking resistance. It can be produced by using a specified transition metal compound as the catalyst. |