| 摘要 |
PURPOSE:To obtain a terpolymer which can provide films excellent in low-temperature impact resistance, low-temperature heat sealability and heat shrinkage, by copolymerizing ethylene with propylene and an alpha-olefin by use of a specific preactivated catalyst. CONSTITUTION:A catalyst comprising a titanium tetrachloride composition and an organoaluminum halide of the formula: AlR1R2X, wherein R1 and R2 are each an alkyl, an aryl or an alkaryl and X is a halogen, is preactivated with a small amount of a C2-12alpha-olefin and a combination of a trialkylaluminum and an aromatic ester. The terpolymer is produced by polymerizing 1.0-3.5wt% ethylene, 88- 96wt% propylene and 1.0-10.0wt% C4-2alpha-olefin by use of the preactivated catalyst. Here, the preactivation is carried out so that the poly-alpha-olefin formed in the preactivation occupies 1-5wt% of the terpolymer after copolymerization, and then the copolymerization is effected at 45-65 deg.C.
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