Process for producing olefin polymers

Details Process for producing olefin polymers Process for producing olefin polymers

1999-10-26

2001-11-13

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...

C526S127000, C526S170000, C526S128000, C526S129000, C526S172000, C502S117000, C502S152000, C502S155000

Reexamination Certificate

active

06316561

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a method for producing olefinic polymers. More precisely, it relates to a method for producing olefinic polymers, which is characterized in that a small amount of hydrogen is added to the polymerization system and olefins are polymerized in the presence of hydrogen.
BACKGROUND OF THE INVENTION
Improving the polymerization activity of catalysts in olefinic polymer production leads to the reduction in production costs, for which various studies have heretofore been made.
For example, H. H. Brintzinger (J. Polym. Sci.: Part A, Polym. Chem., Vol. 33, 1305-1317 (1995)) and S. Kojoh, et al. (Polymer, Vol. 36, No. 26, 5015-5018 (1995)) say that the activity of catalysts could be increased by controlling the hydrogen concentration in the polymerization system to fall between 3 and 20 mol % or so. Regarding its effect, however, hydrogen added could increase the catalyst activity at most 1.7 times or so, as compared with that in the absence of hydrogen.
On the other hand, known is a method of adding hydrogen that serves as a chain transfer agent, to the polymerization system in olefinic polymer production so as to control the molecular weight of the olefinic polymers produced. The method is employed in industrial-scale olefinic polymer production for which the catalyst used is typically an Mg—Ti-based, composite-type solid catalyst, and also in olefinic polymer production for which is used a metallocene-type catalyst being widely noticed in the art.
For example, in Japanese Patent Laid-Open No. 184179/1994, hydrogen is added to the olefin polymerization system for the purpose of controlling the molecular weight of the olefin polymer produced and/or enhancing the activity of the catalyst used. In its Examples, a metallocene-type catalyst having a single-crosslinked ligand of substituted indenyl groups as crosslinked at their 1-position is used for propylene polymerization, and hydrogen is added to the polymerization system whereby the activity of the catalyst used is enhanced. Regarding its effect, however, hydrogen added could increase the catalyst activity at most 2 times or so, as compared with that in the absence of hydrogen.
In International Patent Laid-Open No. WO96/30380, it is written that the activity of the catalyst used increases with the increase in the amount of hydrogen added to the polymerization system.
In the techniques noted above, the amount of hydrogen to be added to the polymerization system is large, relative to the amount of the olefin to be polymerized. In those, however, the effect of hydrogen added for activating the polymerization system is not large, and the absolute value of the polymerization activity could not be enlarged so much.
Given that situation, the object of the present invention is to provide a method for producing olefin polymers in which the polymerization activity of the catalyst used can be enhanced in a simplified manner and the catalyst used can therefore exhibit high activity.
DISCLOSURE OF THE INVENTION
We, the present inventors have assiduously studied so as to attain the object noted above, and, as a result, have found that, when a metallocene-type catalyst having a double-crosslinked ligand of indenyl or substituted indenyl groups is used in olefin polymerization and when hydrogen is added to the polymerization system, then the polymerization activity of the catalyst can be increased several times or more even though the amount of hydrogen added is smaller than previously, and the catalyst can therefore exhibit much higher polymerization activity. On the basis of this finding, we have completed the present invention.
Specifically, the invention provides a method for producing olefin polymers by polymerizing an olefin in the presence of a metallocene-type catalyst that comprises (A) a double-crosslinked transition metal compound having a structure of a general formula (I):
where
M
1
represents a metal element of Group 4 of the Periodic Table;
E
1
and E
2
each represent a ligand of an indenyl or substituted indenyl group, and form a crosslinked structure via A
1
and
A
2
1
, and E
1
and E
2
may be the same or different;
X
1
represents a a-bonding ligand, and plural X
1
's, if any, may be the same or different;
Y
1
represents a Lewis base;
A
1
and A
2
each represent a crosslinking group, and they may be the same or different, but at least one of them is a hydrocarbon group;
q represents an integer of 1 or 2, and r represents an integer of 0 or 1,
and (B) a compound capable of reacting with the transition metal compound (A) or its derivative to form an ionic complex; wherein the polymerization system is so controlled that the hydrogen concentration in the olefin therein falls between 0.01 and 10 mol %. In preferred embodiments of the method, E
1
and E
2
in formula (I) are substituted indenyl groups, and A
1
and A
2
therein are hydrocarbon groups.
The invention also provides a method for producing olefin polymers by polymerizing an olefin in the presence of a metallocene-type catalyst that comprises (A) a double-crosslinked transition metal compound having a structure of a general formula (I):
where
M
1
represents a metal element of Group 4 of the Periodic Table;
E
1
and E
2
each represent a ligand of an indenyl or substituted indenyl group, and form a crosslinked structure via A
1
and A
2
, and E
1
and E
2
may be the same or different;
X
1
represents a &sgr;-bonding ligand, and plural X
1
's, if any, may be the same or different;
Y
1
represents a Lewis base;
A
1
and A
2
each represent a crosslinking group, and they may be the same or different, but at least one of them is a hydrocarbon group;
q represents an integer of 1 or 2, and r represents an integer of 0 or 1,
and (B) a compound capable of reacting with the transition metal compound (A) or its derivative to form an ionic complex; wherein hydrogen is added to the polymerization system in an amount of from 10 to 20000 mols relative to one mol of the transition metal in the transition metal compound. In preferred embodiments of the method, E
1
and E
2
in formula (I) are substituted indenyl groups, and A
1
and A
2
therein are hydrocarbon groups.
The invention still provides a method for producing olefin polymers by polymerizing an olefin in the presence of a metallocene-type catalyst that comprises (A) a double-crosslinked transition metal compound having a structure of a general formula (I):
where
M
1
represents a metal element of Group 4 of the Periodic Table;
E
1
and E
2
each represent a ligand of an indenyl or substituted indenyl group, and form a crosslinked structure via A
1
and A
2
, and E
1
and E
2
may be the same or different;
X
1
represents a &sgr;-bonding ligand, and plural X
1
's, if any, may be the same or different;
Y
1
represents a Lewis base;
A
1
and A
2
each represent a crosslinking group, and they may be the same or different, but at least one of them is a hydrocarbon group;
q represents an integer of 1 or 2, and r represents an integer of 0 or 1,
and (B) a compound capable of reacting with the transition metal compound (A) or its derivative to form an ionic complex, and in the presence of from 0.01 to 10 mol %, relative to the amount of the olefin existing in the reaction system, of hydrogen. In preferred embodiments of the method, E
1
and E
2
in formula (I) are substituted indenyl groups, and A
1
and A
2
therein are hydrocarbon groups.
The invention still provides a method for producing olefin polymers by polymerizing an olefin in the presence of a metallocene-type catalyst that comprises (A) a double-crosslinked transition metal compound having a structure of a general formula (I):
where
M
1
represents a metal element of Group 4 of the Periodic Table;
E
1
and E
2
each represent a ligand of an indenyl or substituted indenyl group, and form a crosslinked structure via A
1
and A
2
, and E
1
and E
2
may be the same or different;
X
1
represents a &sgr;-bonding ligand, and plural X
1
's, if any, may be the same or different;
Y
1
represents a Lewis base;
A
1

Affiliated with

Also associated with

Rating

Process for producing olefin polymers does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for producing olefin polymers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing olefin polymers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2586242