GB880747A - Improvements in and relating to the catalytic polymerisation of olefins - Google Patents

Abstract

Polymers of alpha-mono-olefines containing at least three carbon atoms in the molecule are made by polymerizing one or more of the monomers in the presence of a catalyst comprising titanium trichloride and an aluminium alkyl compound, and sufficient of a zinc dialkyl and/or diaryl compound to produce a polymer whose molecular weight is substantially lower than that of a polymer produced in the absence of said zinc compound under otherwise equal conditions. The polymerization may also be effected in the additional presence of an aliphatic tertiary or secondary amine having at least five carbon atoms per molecule, an aliphatic primary amine having at least 4 carbon atoms per molecule, or a heterocyclic nitrogen compound having 5- or 6-membered rings and an alkyl substituent of up to 6 carbon atoms on one or both carbon atoms alpha to the nitrogen atom in the ring. The polymerization is generally carried out in the presence of an organic solvent or diluent such as benzene, heptane, or iso-octane. Mono-olefines specified are propylene, 1-butene, 1-pentene, 3-methyl-1-pentene, and 1-decene. The polymerization may also be carried out in the presence of ethylene, e.g. to give a copolymer of propylene and ethylene. The zinc dialkyls and/or aryls may be added to the catalyst, or at any stage of the reaction. If desired, they may be formed in situ, e.g. by adding a zinc compound, such as the fluoride or stearate, which interacts with the aluminium alkyl of the catalyst to form a zinc alkyl and an aluminium salt. The titanium trichloride of the catalyst may be a commercial product, but preferably it is formed by reducing titanium tetrahalide with an aluminium trialkyl in a two stage process until the mol. ratio of total aluminium to titanium is 1:1, or by partially reducing titanium tetrahalide with an aluminium trialkyl and subsequently completing the reduction to give the above ratio by using a dialkyl aluminium chloride. The organo zinc compound may be zinc diethyl, di-n-propyl, di-isopropyl, di-isobutyl, di-isoamyl, diphenyl or ditolyl. The organo-aluminium compound of the catalyst may be aluminium diethyl chloride, aluminium diethyl bromide, aluminium triethyl, aluminium tri-isobutyl, or aluminium tri-isopropyl. Triethyl amine is the exemplified nitrogen-containing compound. The polymer is recovered from the polymerizate by conventional techniques. Specifications 799,823 and 810,023 are referred to.