Patent ID: 7737239

Claim:
A propylene elastomer (PBER) comprising: (a) 50 to 85 mol % of units derived from propylene, (b) 5 to 25 mol % of units derived from 1-butene and (c) 10 to 25 mol % of units derived from ethylene, and having: a molar ratio of propylene content to ethylene content of from 89/11 to 70/30, and a modulus in tension (YM), as measured in accordance with JIS 6301, of not more than 40 Mpa, wherein said propylene elastomer (PBER) is produced by using a metallocene catalyst system comprising a transition metal compound represented by the following formula (1a): wherein R 3 is selected from the group consisting of a hydrocarbon group and a silicon-containing group; R 1 , R 2 and R 4 are identical or different from one another and selected from the group consisting of a hydrogen, a hydrocarbon group and a silicon-containing group; R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 and R 14 are identical or different from one another and are selected from the group consisting of a hydrogen, a hydrocarbon group and a silicon-containing group, or adjacent substituent groups R 5 to R 12 are optionally linked to each other to form a ring, R 13 and R 14 are the same or different from each other and are optionally linked to each other to form a ring; M is a Group 4 transition metal; Y is a carbon atom; each Q is identical or different from each other and selected from the group consisting of a halogen, a hydrocarbon group, an anionic ligand and a neutral ligand capable of coordination with a lone pair of electrons, and j is an integer of 1 to 4.