Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Patent
1995-09-27
1999-01-12
Bell, Mark L.
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
502123, 502129, 502132, 576160, 576346, 576943, 556 43, 556 52, 556 58, B01J 3100, B01J 3700, C08F 402, C08F 460
Patent
active
058589040
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a catalyst for producing a vinyl-based polymer such as a polyolefin, and a process for producing a vinyl-based aromatic polymer by using the same, especially a process for efficiently producing a styrenic polymer having a low molecular weight.
BACKGROUND ART
There have heretofore been known the processes for producing high-performance styrenic polymers having a high degree of syndiotactic configuration in high yield by allowing a reaction product of an aluminoxane with a transition metal complex to act on styrene. (Refer to Japanese Patent Application Laid-Open Nos. 187708/1987, 179906/1988, 241009/1988, etc.) The catalyst system containing an aluminoxane has the advantage of high activity, but it is required in the case of methylaluminoxane which has a particularly high activity to use a large amount thereof against a transition metal compound. In particular in order to obtain a styrenic polymer having a molecular weight of 600,000 or less, it is necessary to add a large amount of a Lewis acid to the reaction system or set the temperature at the time of polymerization to a high level. The above-mentioned necessity is responsible for such problems as a large amount of ash remaining in the product polymer and deteriorated catalytic activity.
As a catalyst free from an aluminoxane for producing a styrenic polymer and a process for producing the same without the use of an aluminoxane, there is disclosed in Japanese Patent Application Laid-Open No. 249504/1992, a method for polymerizing a styrenic monomer by the use of a catalyst system which comprises a transition metal compound and a non-coordination ionic compound. However in the case of producing a polymer, a catalyst system not containing an aluminoxane causes difficulty in controlling the molecular weight of the product polymer as compared with a catalyst system containing an aluminoxane. In particular, in order to obtain a styrenic polymer having a weight-average molecular weight of 600,000 or less, it is still necessary to add a large amount of a molecular-weight depressant to the polymerization system or to set the polymerization reaction temperature at a high level. Such necessity brings about a decrease in the catalytic efficiency and an increase in the amount of residual ash, thereby increasing the polymer production cost and deteriorating the physical properties of the resulting polymer.
Under such circumstances, it is an object of the present invention to provide a catalyst for producing a vinyl-based polymer capable of efficiently producing a vinyl product-addition polymer such as polystyrene and polyolefin as well as a process for efficiently producing in a low production cost, an aromatic polymer having a low molecular weight and a high degree of syndiotactic configuration.
DISCLOSURE OF THE INVENTION
As a result of intensive research and investigation accumulated by the present inventors for the purpose of attaining the above-mentioned object, it has been found that the object can be attained by the use of a polymerization catalyst which comprises in combination, a transition metal compound having a tetra-substituted cyclopentadienyl group as a .pi.-ligand, a specific promoter or an ionic complex and a Lewis acid. The present invention has been accomplished on the basis of the foregoing finding and information. In addition, the present invention provides more useful means for solving such problems as catalytic efficiency, thermal stability of the transition metal compound itself, ease of purfication, molecular weight of the resultant polymer etc. in the case of using the above-mentioned transition metal compound having a tetra-substituted cyclopentadienyl group as a .pi.-ligand.
Specifically, the present invention provides in combination, an (A) transition metal compound having a tetra-substituted cyclopentadienyl group as a .pi.-ligand, a (B) aluminoxane and/or ionic compound having a non-coordinating anion and a cation and a (C) Lewis acid; and comprises producing a vinyl-based aromati
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Shouzaki Hajime
Takeuchi Mizutomo
Tomotsu Norio
Bell Mark L.
Idemitsu Kosan Co. Ltd.
Pasterczyk J.
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