GB828791A - Method of selectively polymerising alpha-olefins - Google Patents

Abstract

A catalyst used in the polymerization of olefins and consisting of a compound of a Group IVa, Va or VIa metal "in contact with" (defined in the Specification) metal alkyl groups containing Al or a Group II metal, is obtained in the solid or non-solid form either by the choice of components or by the separation (filtration, decantation, &c.) of a catalyst containing solid and non-solid forms. The solid form is meant to be the materials which are not capable of micellar dispersion in the medium used, whereas by non-solid is meant a material which dissolves or disperses. The Specification describes the production of catalysts from halides, oxyhalides, hydroxides, alkoxyhalides and alkoxides of Ti, Zr, V, Cr and W in conjunction with organo aluminium compounds and it is said that complexes are formed, although in the case of solids this may be on the surface only. Reference has been directed by the Comptroller to Specification 810,023.ALSO:a -Olefins of at least 3 carbon atoms are polymerized to linear, head-to-tail polymers by the use as catalyst of a compound of a Group IVa, Va or VIa metal "in contact with" (defined in the Specification) metal alkyl groups containing Al or a Group II metal, and characterized in that the polymerization is selectively regulated towards an increased crystallizable (isotactic) or non-crystalline (atactic) content by the use of catalyst in either the substantially solid or substantially non-solid form, the appropriate form resulting from the choice of components and conditions of formation, or from an intermediate step of preparing catalyst having solid and non-solid forms, wherein separation may then be effected by filtration, decantation, sedimentation, centrifuging or flotation. The non-solid form of catalyst includes materials in the state where they are dissolved or dispersed in the reaction medium used, while the solid form includes materials not capable of micellar dispersion. The Specification describes the production of catalysts from halides, oxyhalides, hydroxides, alkoxyhalides and alkoxides of the metals Ti, Zr, V, Cr and W in conjunction with organo aluminium compounds and it is suggested that complexes are formed although in the case of solid catalysts this may be only at the surface of the heavy metal compound. The monomers, solvents, reactions and fractionation of products may be as disclosed in Specification 810,023. When the alkyl groups of the metal alkyl contain up to 4 C atoms the production of crystallizable polymers may be favoured, whereas the use of lyophilic groups (e.g. alkoxy, hydroxy, C5 to C16 alkyl) in the catalyst components favours the non-crystalline polymer. In examples polymers of high crystallinity are obtained from propylene, butene and styrene by the use of catalysts derived from TiCl2 + AlEt3, and TiCl3 with AlEt3, AlPr3, AlBu3 or AlEt2Cl. Products of low crystallinity are obtained from TiCl4 with Al(C4H9)3, Al(C6H13)3, Al(C16H33)3 or Al(C12H25)2Cl; AlEt3 with Ti butylates or propylates; AlEt3 with Ti(OH)4, TiI3, CrOCl2, WCl6 or VCl4; VOCl3 + Al (C6H33)3; and Al(C10H21)3 with CrCl3, ZrCl4 or VCl4. The use as catalysts of filtered products and filtrates from AlEt3 + TiCl4 or VCl4 is also described. The examples also disclose the addition of catalyst components during polymerization, and the use of materials such as methanol, ether, benzene, toluene, and hydrochloric acid in the purification of the products. Reference has been directed by the Comptroller to Specification 810,023.