| 摘要 |
Hetero block copolymers comprising sequences of alternate non-random distributed sections, each section consisting of a homopolymer of ethylene or an alpha-olefin or of a different random copolymer comprising monomeric units of ethylene and/or an alpha-olefin are made by a process which involves polymerizing the monomer or mixtures of monomers alternately, each stage being continued for a predetermined time depending on the length of the required blocks, the polymerization being effected in the presence of a catalyst containing a compound of transitional metals of Group IVa, Va and/or VIa of the Periodic Table according to Mendeleeff in a valency state lower than the maximum and a metalloorganic compound of metals of Group I, II and/or III of the Periodic Table. Olefines specified are ethylene, propylene, butene and pentene. The examples describe the use of a titanium trichloride-aluminium triethyl catalyst to prepare propylene-ethylene and propylene(ethylene-propylene) block copolymers, the reactions being carried in the presence of toluene or xylene as an inert diluent. The resulting polymers may be used in the preparation of graft polymers, e.g. an ethylene-butene block copolymer may be peroxidized and then grafted with vinyl chloride, styrene, methyl methacrylate or methyl acrylate. |
