TH26694A - Method for the Preparation of Ethylene Polymer Compositions - Google Patents

Abstract

Methods for preparing ethylene polymer compositions with a density of 0.86-0.94 g/cm³ and a limiting viscosity (n) of 1-6 dl/g have been revealed using olefin polymerization catalysts composed of transition metal compounds with cycloalkadienyl ligands and ordanoaluginum oxy compounds. Methods for preparing ethylene polymer compositions with a density of 0.87-0.93 g/cm³ and a limiting viscosity (n) of 0.5-6 dl/g have also been revealed.

Claims (4)

1. A method for the preparation of ethylene polymer compounds with a density of 0.87-0.93 g/cm³ and a limiting viscosity (n) of 0.5-6 dl/g, which consists of a multi-step process comprising a polymerization step (C) in which ethylene and a-olefin are polymerized using an olefin polymerization catalyst [II] containing a transition metal (A) composed of a cycloalgadienyl ligand. and organoaluminum oxy compounds (B) to produce ethylene copolymer[III] with a density less than 0.91 g/cm³ and a limit viscosity [n] of 0.5-6 dl/g and step polymerization (d) in which ethylene or other a-olefins are polymerized by using an olefin polymerization catalyst [III] containing a titanium catalyst [C] prepared from a titanium compound represented by the formula Ti(O-R)gX4-g (where R is the hydrocarbon group, x is the halogen and 0 <= g <= 4) and containing titanium, magnesium and halogen as the main components. Organoaluminum compounds (D) and/or organoaluminum oxy compounds [E] are used to produce an ethylene copolymer [IV] with a density higher than that of the ethylene copolymer [III] and a limiting viscosity [n] of 0.5–6 dl/g, in which polymerization steps (c) and (d) are performed sequentially such that step (d) is performed with the ethylene copolymer [III] obtained in step (c) already performed, or step (c) is performed with the ethylene polymer [IV] obtained in step (d) already performed, resulting in an ethylene polymer [IV] volume of 10–1000 parts by weight of 100 parts by weight of the ethylene copolymer [III]. 2. Method for the preparation of ethylene polymer compounds according to Patent 1 where the transition metal of the transition metal compound (A) is zirconium, titanium, hafnium, chromium or vanadium. 3. A method for the preparation of the ethylene polymer composition according to claim 2, where polymerization steps (c) and (d) are performed in such a sequence that step (d) is performed with the ethylene polymer [III] obtained in step (c) which was performed earlier. 4. Method for preparing ethylene polymer composition according to claim 2, where the amount of ethylene copolymer [IV] in the polymerization step (d) is 20 - 500 parts by weight, while the amount of ethylene polymer [III] obtained in the polymerization step (c) is 100 parts by weight.