Polymerization catalyst system using di-se-butyl dimethyoxysilane for preparation of polypropylene
AssigneeFina Technology, Inc.
InventorJoseph Thorman
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Abstract
It has been discovered that using di-sec-butyldialkoxysilanes, such as di-sec-butyldimethoxysilane (DSBDMS), as external electron donors for Ziegler-Natta catalysts can provide a catalyst system that may prepare polypropylene films with improved properties and processing. The catalyst systems of the invention provide high activity, high bulk density, moderate hydrogen response, moderate donor response and high polydispersity (MWD). Suitable di-sec-butyldialkoxysilanes have the formula (sBu)2Si(OR″)2, where R″ is independently a straight or branched alkyl group of 1-5 carbon atoms.
Claims13
A catalyst system for the polymerization or copolymerization of olefins comprising:
- a Ziegler-Natta catalyst;
- an organoaluminum compound co-catalyst;
- and
- at least one external electron donor comprising a di-sec-butyldialkoxysilane having the formula (sBU)2Si(OR″)2, where R″ is independently a straight or branched alkyl group of 1-5 carbon atoms.
A catalyst system for the polymerization or copolymerization of olefins comprising:
- a Ziegler-Natta catalyst, where the Ziegler-Natta catalyst comprises a transition metal compound of the formula MRx where M is selected from the group consisting of titanium, chromium, and vanadium, R is selected from the group consisting of halogen or a hydrocarboxyl, and x is an integer up to and including the maximum valence of M as dictated by its position in the Periodic Table;
- an organoaluminum compound co-catalyst;
- and
- at least one external electron donor selected from the group consisting of di-sec-butyldimethoxysilane (DSBDMS), di-sec-butyldiethoxysilane (DSBDES), di-sec-butylmethoxyethoxysilane, and mixtures thereof,
- where the Al/Si molar ratio (organoaluminum compound to silane donor) ranges from about 0.5 to about 500.
Polypropylene comprising a propylene polymer or copolymer having a melt flow ranging from about 1-100 decigrams/min., a polydispersity ranging from about 7 to about 11, and xylene solubles ranging from about 0.5 to about 6 wt %.
Polypropylene formed by a process comprising:
- providing a Ziegler-Natta catalyst, and in any order:
- contacting the catalyst with an organoaluminum compound;
- contacting the catalyst with at least one electron donor comprising a di-sec-butyldialkoxysilane simultaneously with or subsequent to contacting the catalyst with an organoaluminum compound, where the di-sec-butyldialkoxysilane has the formula (sBu)2Si(OR″)2, where R″ is independently a straight or branched alkyl group of 1-5 carbon atoms;
- introducing the catalyst into a polymerization reaction zone containing the organoaluminum compound, the electron donor and propylene monomer;
- and
- removing polypropylene homopolymer or copolymer from the polymerization reaction zone.
An article formed from polypropylene comprising a propylene polymer or copolymer having a melt flow ranging from about 1-100 decigrams/min. and xylene solubles of not more than about 6% formed by a process comprising:
- providing a Ziegler-Natta catalyst, and in any order:
- contacting the catalyst with an organoaluminum compound;
- contacting the catalyst with at least one electron donor comprising a di-sec-butyldialkoxysilane simultaneously with or subsequent to contacting the catalyst with an organoaluminum compound, where the di-sec-butyldialkoxysilane has the formula (sBu)2Si(OR″)2, where R″ is independently a straight or branched alkyl group of 1-5 carbon atoms;
- introducing the catalyst into a polymerization reaction zone containing the organoaluminum compound, the electron donor and propylene monomer;
- and
- removing polypropylene homopolymer or copolymer from the polymerization reaction zone.
Dependencies are inferred from the claim text.