METHOD OF NARROWING DISTRIBUTION OF SHORT-CHAIN BRANCHINGS IN TWO-STAGE ETHYLENE POLYMERISATIONS AND IN THEIR PRODUCTS Russian patent published in 2009 - IPC C08F210/16 C08F297/08 C08F2/44 

FIELD: chemistry.

SUBSTANCE: invention relates to improved two-stage method, in which in first polymerisation reactor ethylene homopolymer is obtained, and in second polymerisation reactor ethylene-α-olefin copolymer is obtained; said polymerisations being carried out in inert hydrocarbon medium using solid highly active catalyst, which contains transitive metal, and aluminium-organic co-catalyst, and said homopolymer and co-polymer are joined obtaining product in form of final polyethylene resin, ensuring narrowing of distribution of short-chain branchings in ethylene-α-olefin copolymer, which differs by the fact that it includes carrying out copolymerisation in second polymerisation reactor in presence of from 1 to 100 p/mln, calculated per amount of inert hydrocarbon, monoalkyltrialkoxysilane, described by formula R²Si(OR³)₃, where R² represents C_1-10 alkyl group, and R³ represents C_1-5 alkyl group, with simultaneous preservation in reactor of such conditions and rates of raw material supply, at which obtained is copolymer which has density equal 0.940 g/cm³ or less and contains 90% or more of copolymer with low degree of short-chain branchings, having fewer than 10 branchings per 1000 carbon atoms.

EFFECT: method allows to obtain resins demonstrating improved physical characteristics.

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