Process for producing propylene-ethylene block copolymers
Abstract
Abstract A process for producing propylene-ethylene block copolymers by a three-step polymerization technique using a stereoregular catalyst, characterized in that the first-step polymerization is carried out by supplying propylene alone or a propylene/ethylene mixture so that the ethylene/propylene reaction ratio is 6/94 or less, thereby polymerizing 60 to 95% by weight of the total polymerization amount, the second-step polymerization is carried out by supplying a propylene/ethylene mixture so that the ethylene/propylene reaction ratio is 15/85 to 79/21, thereby polymerizing 1 to 20% by weight of the total polymerization amount, and the third-step polymerization is carried out by supplying a propylene/ethylene mixture so that the ethylene/propylene reaction ratio is 50/50 to 89/11, thereby polymerizing 4 to 35% by weight of the total polymerization amount, with the ethylene/propylene reaction ratio in the third step made larger than that in the second step. Said process can give propylene-ethylene block copolymers markedly well balanced in impact strength, stiffness, transparency and impact blushing.
Inventors
- 👤 Akinobu Shiga
- 👤 Masahiro Kakugo
- 👤 Hajime Sadatoshi
- 👤 Kazuki Wakamatsu
- 👤 Hiroshi Yoshioka
Bibliographic Details
Claims Analysis
Total Claims: 6References Cited (Backward Citations)
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