Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By addition of entire unsaturated molecules – e.g.,...
Reexamination Certificate
1998-06-12
2001-01-23
Wood, Elizabeth D. (Department: 1755)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By addition of entire unsaturated molecules, e.g.,...
C585S502000, C585S506000, C585S511000
Reexamination Certificate
active
06177603
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the use of diethylzinc to reduce the viscosity of the polymer cement in the rare earth catalyzed polymerization of butadiene.
BACKGROUND OF THE INVENTION
Problems have existed in the synthesis of polyconjugated dienes broadly and specifically in the synthesis of polybutadiene, including: the reduction the polymer cement viscosity in the polymer product; suppression of gel formation in the reaction mass; and, the reduction of a broad weight distribution in the polymer product.
The use of various catalyst systems containing rare earth compounds for the polymerization of conjugated diene monomers has been disclosed. Examples of such disclosures are (1) Mazzei A., Makromol. Chem. Suppl. 4 61 (1981); (2) Witte J., Angew. Makromol. Chem. 94 119 (1981); (3) Shen Tse-Chuan et al, J. Pol. Sci. Polym. Chem. Ed. 18 3345 (1980); (4) Marwede G. and Sylvester G., Trans. 22nd Annual Proceedings of the International Institute of Synthetic Rubber Producers, Madrid Paper III-3 (1981). Such catalyst systems have two or three components, for example a lanthanoid alkyl, alkoxide or salt (e.g. neodymium tricarboxylate) with an organoaluminium compound and optionally a Lewis Acid. When used in the polymerization of conjugated dienes, they yield a product which has a high content of cis isomer (e.g. 98% for polybutadiene and 94% for polyisoprene)
Diethylzinc (hereinafter referred to as “Et
2
Zn”) is well known as a chain transfer agent in the Zeigler-Natta polymerizations as described in J. Boor, “
Zeigler
-
Natta Catalysts and Polymerizations
”, 1979, p375. Diethylzinc has also been used in BuLi and barium catalyzed polymerizations of butadiene as described in H. Hseih,
J Polym. Sci
., Polym. Chem. Ed., Vol. 14, p379-386, 1976; and, U.S. Pat. Nos. 4,129,705 and 4,092,268, to de Zaraux. EP Patent Application No. 0234 512 to Takeshi, teaches that Et
2
Zn can be used in combination with rare earth catalyzed polymerizations of butadiene, as a third, nonessential catalyst component of the system. However, Takeshi makes no disclosure that Et
2
Zn may be used reduces the viscosity of the polymerization.
Thus, there exists a long felt need to vary the molecular weight of polybutadienes during synthesis; more particularly, to reduce the polymer cement viscosity of polybutadienes during their synthesis. The instant invention purports to solve all of the foregoing problems without noticeably affecting the rate of the polymerization or the microstructure of the resultant polymer.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a three component catalyst system for the polymerization of butadiene.
More specifically, it is an object of the invention to provide an organo zinc component such as Et
2
Zn to augment the primary rare earth organic salt and dialkylmagnesium components of a catalyst system for polymerizing butadiene.
Still more specifically, it is the primary object of the present invention to substantially reduce the polymer cement viscosity of the polymerization reaction mass as a direct and proximate result of adding the third organo zinc component to the catalyst system.
Moreover, as a direct and proximate result of the addition of the organo zinc component to the catalyst system, it is an object of the invention to substantially suppress gel formation and substantially reduce the molecular weight distribution of the reaction mass during high temperature polymerization of butadiene in the presence of catalytically effective amounts of primary rare earth organic acid salt and a dialkylmagnesium components.
Further, it is an object of the instant invention to add substantial catalytically effective amounts of organo zinc to respective catalytically effective amounts of a primary rare earth organic acid salt and a dialkylmagnesium components in the high temperature polymerization of butadiene, without substantially affecting the rate of polymerization or without adversely affecting the microstructure of the resultant polybutadiene polymer product.
Finally, it is the primary object of the instant invention to provide a catalyst system based upon a rare earth metal or a complex of a rare earth metal/dialkylmagnesium catalyst and an organo zinc component.
REFERENCES:
patent: 2921060 (1960-01-01), Stuart
patent: 3070549 (1962-12-01), Ziegler et al.
patent: 4092268 (1978-05-01), De Zarauz
patent: 4129705 (1978-12-01), de Zarauz
patent: 4384982 (1983-05-01), Martin
patent: 4518753 (1985-05-01), Richards et al.
patent: 4611038 (1986-09-01), Brun et al.
patent: 4689368 (1987-08-01), Jenkins
patent: 5159022 (1992-10-01), Ikematu et al.
patent: 5686371 (1997-11-01), Ansell et al.
patent: 87102388 (1987-02-01), None
“Butadiene polymerization With a Rare Earth Compound Using a Magnesium Alkyl Cocatalyst: 2” by D.K. Jenkins,Polymer, vol. 26, pp. 152-158, Jan., 1985.
Bridgestone Corporation
Burleson David G.
Reginelli Arthur M.
Wood Elizabeth D.
LandOfFree
Organo zinc and rare earth catalyst system in the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Organo zinc and rare earth catalyst system in the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Organo zinc and rare earth catalyst system in the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2544575