Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-02-01
2003-04-22
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S124300, C526S351000, C526S158000, C526S123100, C502S103000, C502S118000, C502S158000, C556S009000
Reexamination Certificate
active
06552136
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an organosilicon compound, to a catalyst for olefin polymer production, and to a method for producing olefin polymers. More precisely, the invention relates to an organosilicon compound having a specific structure, to a catalyst comprising the compound for producing olefin polymers having increased stereospecificity and increased melt fluidity, and to a method for producing such olefin polymers.
BACKGROUND ART
As having a high degree of crystallinity, olefin polymers, especially polypropylenes are tough and have good tensile strength, heat resistance, chemical resistance and optical characteristics, and are well workable. In addition, they are more lightweight than polystyrenes, and are much used in the field of injection moldings, containers, wrapping and packaging materials, etc.
However, in order to further broaden the application field of polypropylenes, their toughness and heat resistance that are inferior to those of polystyrenes and ABS resins must be further improved. It is known that olefin polymers having a higher degree of stereospecificity have higher toughness and better heat resistance. Therefore, it is desired to further increase the stereospecificity of olefin polymers.
In general, olefin polymers are produced by the use of Ziegler-Natta catalysts comprising a titanium compound and an organoaluminium compound, for which, therefore, tried are (1) increasing catalyst activity, (2) increasing the stereospecificity of olefin polymers produced, and (3) improving the powdery morphology of olefin polymers for their stable production.
In producing polypropylenes, generally used is a catalyst system that comprises a solid catalyst component composed of titanium, magnesium, chlorine and an electron donor compound, and an organoaluminium compound. It is known that adding an organosilicon compound with Si—O—C bonds to the catalyst system increases the stereospecificity of the polymers produced. For example, Japanese Patent Laid-Open No. 84404/1990 discloses a catalyst system that comprises a cyclopentylalkyldimethoxysilane, dicyclopentyldimethoxysilane or the like. However, the silicon compound-containing catalyst system disclosed is problematic in that the melt fluidity dependency of the polymers produced on the amount of hydrogen used in their production is low, and therefore a larger amount of hydrogen must be used for producing polymers having increased melt fluidity, which, however, detracts from the productivity of the polymers since the monomer partial pressure shall be low.
On the other hand, Japanese Patent Laid-Open No. 223008/1988 discloses a catalyst system containing di-n-propyldimethoxysilane or the like, in which the silicon compound used increases the melt fluidity dependency of the polymers produced on the amount of hydrogen used in their production. However, the stereospecificity of the polymers produced by the use of the catalyst system is still unsatisfactory, and the polymers are still problematic in that their moldings could not still have a desired degree of toughness. Therefore, for obtaining tough moldings of the polymers, their wall thickness must be increased, for which the amount of the polymers to be used shall increase.
The object of the present invention is to provide a catalyst for olefin polymer production, which is effective for producing olefin polymers having increased stereospecificity and increased melt fluidity, and also to provide a method for producing such olefin polymers.
DISCLOSURE OF THE INVENTION
We, the present inventors have assiduously studied in order to attain the object as above, and, as a result, have found that the problems noted above can be solved by the use of a catalyst for olefin polymer production that comprises a solid catalyst component composed of titanium, magnesium and an electron donor compound, an organoaluminium compound, and a novel organosilicon compound of a general formula (I) mentioned below. On the basis of this finding, we have completed the present invention.
Specifically, the invention provides an organosilicon compound, a catalyst for olefin polymer production, and a method for producing olefin polymers, which are mentioned below.
(1) An organosilicon compound of a general formula (I):
wherein R
1
to R
3
each represent a hydrogen atom or a hydrocarbon group, and they may be the same or different, and may be bonded to the adjacent group to form a ring; R
4
and R
5
each represent a hydrocarbon group, and they may be the same or different, and may be bonded to the adjacent group to form a ring; R
6
and R
7
each represent a linear hydrocarbon group having from 1 to 10 carbon atoms, and they may be the same or different; m is an integer of at least 2; and n is an integer of at least 1.
(2) A catalyst for olefin polymer production, which comprises (A) a solid catalyst component comprising titanium, magnesium and an electron donor compound, (B) an organoaluminium compound, and (C) the organosilicon compound of (1).
(3) A method for producing olefin polymers, which comprises polymerizing an olefin by the use of the olefin polymer production catalyst of (2).
(4) The method for producing olefin polymers of (3), wherein the olefin is propylene.
BEST-MODES OF CARRYING OUT THE INVENTION
The organosilicon compound of the invention is a novel compound having the structure of above-mentioned general formula (I). That is, the compound is represented by:
wherein R
1
to R
3
each represent a hydrogen atom or a hydrocarbon group, and they may be the same or different, and may be bonded to the adjacent group to form a ring; R
4
and R
5
each represent a hydrocarbon group, and they may be the same or different, and may be bonded to the adjacent group to form a ring; R
6
and R
7
each represent a linear hydrocarbon group having from 1 to 10 carbon atoms, and they may be the same or different; m is an integer of at least 2; and n is an integer of at least 1.
Concretely, R
1
to R
3
include a hydrogen atom; linear hydrocarbon groups such as methyl, ethyl and n-propyl groups; branched hydrocarbon groups such as isopropyl, isobutyl, t-butyl and thexyl groups; saturated cyclic hydrocarbon groups such as cyclobutyl, cyclopentyl and cyclohexyl groups; and unsaturated cyclic hydrocarbon groups such as phenyl and pentamethylphenyl groups. Of those preferred are a hydrogen atom and linear hydrocarbon groups having from 1 to 6 carbon atoms; and especially preferred are a hydrogen atom, and methyl and ethyl groups.
R
4
and R
5
include linear hydrocarbon groups such as methyl, ethyl and n-propyl groups; branched hydrocarbon groups such as isopropyl, isobutyl, t-butyl and thexyl groups; saturated cyclic hydrocarbon groups such as cyclobutyl, cyclopentyl and cyclohexyl groups; and unsaturated cyclic hydrocarbon groups such as phenyl and pentamethylphenyl groups. These may be the same or different. Of those, preferred are linear hydrocarbon groups having from 1 to 6 carbon atoms; and especially preferred are methyl and ethyl groups.
R
6
and R
7
include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl and n-octyl groups. These may be the same or different. Of those, preferred are linear alkyl groups having 1 or 2 carbon atoms; and especially preferred is a methyl group.
Typical examples of the organosilicon compound of formula (I) are those where R
1
to R
3
each are a hydrogen atom, or a linear hydrocarbon group having from 1 to 6 carbon atoms, and they may the same or different, and may be bonded to the adjacent group to form a ring; R
4
and R
5
each are a linear hydrocarbon group having from 1 to 6 carbon atom, and they may be the same or different, and may be bonded to the adjacent group to form a ring; and R
6
and R
7
each are a linear alkyl group having 1 or 2 carbon atoms, and they may be the same or different, and may be bonded to the adjacent group to form a ring.
Concretely, preferred examples of the organosilicon compound of formula (I) are neopentyl-n-propyldimethoxysilane, neopentyl-n-butyldimethoxysilane, neopentyl-n-penty
Isozaki Toshio
Kadoi Yasunori
Katayama Kiyokazu
Ota Tsuyoshi
Sadashima Takanori
Choi Ling-Siu
Idemitsu Petrochemical Co. Ltd.
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