Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1997-12-23
2001-03-13
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S151000, C526S169100, C526S335000, C525S914000
Reexamination Certificate
active
06201080
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a catalyst system for the production of syndiotactic 1,2-polybutadiene.
BACKGROUND OF THE INVENTION
Pure syndiotactic 1,2-polybutadiene (SPB) is a thermoplastic resin which has double bonds attached in an alternating fashion to its polymeric backbone. Films, fibers and molded articles can be made utilizing syndiotactic 1,2-polybutadiene. It can also be blended into rubbers and cocured therewith. Syndiotactic 1,2-polybutadiene can be made by solution, emulsion or suspension polymerization. It typically has a melting point which is within the range of about 195° C. to about 215° C. Many transition metal catalyst systems based on titanium, vanadium, chromiumm, molybdenum, palladium, iron and cobalt have been reported in the prior art for the preparation of syndiotactic 1,2-polybutadiene (see, i.e., J. Boor, Jr., Ziegler-Natta Catalysts and Polymerizations, Academic Press: New York, 1979, P. 144). However, the majority of these catalyst systems have no industrial application because they have insufficient polymerization activity and stereoselectivity and in some case produce low molecular weight polymers or cross-linked polymers unsuitable for commercial use. The following cobalt-containing catalyst systems have been widely known for the preparation of syndiotactic 1,2-polybutadiene:
I. Cobalt dibromide/triusobutyl aluminum/water/triphenyl phosphine disclosed in U.S. Pat. No. 4,182,813, assigned to Japan Synthetic Rubber Co. Ltd.; and,
II. Cobalt tris(acetylacetonate)/triethyl aluminum/water/carbon disulfide disclosed in U.S. Pat. No. 3,778,424, assigned to Ube Industries Ltd.
These two catalyst systems also have serious disadvantages. The cobalt dibromide/triisobutyl aluminum/water/triphenyl phosphine system yields syndiotactic 1,2-polybutadiene having low crystallinity. In addition, this catalyst system develops sufficient catalytic activity only in halogenated hydrocarbon solvents as polymerization medium, and halogenated solvents present the problems of toxicity. The second catalyst system uses carbon disulfide as one of the catalyst components, thereby necessitating the use of special safety measures due to its high volatility, low flash point as well as toxicity. Accordingly, many restrictions are required for the industrial utilization of the said catalyst system. Furthermore, the syndiotactic 1,2-polybutadiene produced with this catalyst system has a very high melting point (200° C. to 210° C.) and is therefore difficult to process.
Coordination catalysts based on chromium compounds such as triethylaluminium/chromium tris(acetylacetonate) have a low activity and have not been usable on a technical scale. JP-A-7306939 and JP-A-7364178, both assigned to Mitsubishi, disclose a process for polymerization of 1,3-butadiene to amorphous 1,2-polybutadiene by using a ternary catalyst system comprising (A) a soluble chromium compound, (B) a trialky aluminum compound, and (C) a dialkyl hydrogen phosphite. The product was reported to be a white rubbery polymer containing a portion of gel and displaying no obvious melting point.
U.S. Pat. No. 4,751,275, assigned to Bayer, discloses a process for the preparation of SPB by the solution polymerization of 1,3-butadiene in a hydrocarbon polymerization medium, such as benzene, toluene, cyclohexane, or n-hexane. The catalyst system used in this solution polymerization contains a chromium-III compound which is soluble in hydrocarbons, a trialkylaluminum compound, and di-neopentylphosphite or neopentylmethylphosphite. However, the polymerization product was not well charaterized as neither the melting temperature nor the degree of syndiotacticity is reported.
U.S. Pat. No. 4,168,357 and U.S. Pat. No. 4,168,374, assigned to Goodyear, describe chromium-containing catalysts for the preparation of high cis-1,4-polypentadiene.
Notwithstanding the foregoing prior art, it would be advantageous to produce a new and improved catalyst system that can be used to produce a syndiotactic 1,2-polybutadiene product having a higher melting point and increased syndiotacticity compared to the syndiotactic 1,2-polybutadiene produced by the processes of the prior art.
The object of this invention is to overcome the disadvantages of the prior art and provide a new and improved catalyst system for the production of syndiotactic 1,2-polybutadiene having a higher melting point and increased syndiotacticity over syndiotactic 1,2-polybutadiene products of the prior art.
SUMMARY OF THE INVENTION
The instant invention relates to a method for forming a syndiotactic 1,2-polybutadiene product having a syndiotacticity of more than 66.5% prefererably more than 70% and a melting temperature of more than about 100° C., prefererably than about 140°. The method includes polymerizing 1,3-butadiene, in the presence of catalytically effective amounts of: (a) an organomagnesium compound; (b) a chromium compound; and, (c) a dihydrocarbyl hydrogen phosphite. The present invention also contemplates a product of the method and an article made from the product.
DETAILED DESCRIPTION OF THE INVENTION
The present invention teaches a process for producing syndiotactic 1,2-polybutadiene by polymerizing 1,3-butadiene with a catalyst system comprising: (a) a hydrocarbon-soluble chromium compound, (b) an organomagnesium compound, and (c) a dihydrocarbyl hydrogen phosphite.
The chromium compound employed in the catalyst system of the instant invention is soluble in a hydrocarbon solvent such as aromatic hydrocarbons, aliphatic hydrocarbons or cycloaliphatic hydrocarbons and includes, but is not limited to, chromium carboxylates such as chromium 2-ethylhexanoate, chromium neodecanoate, chromium naphthenate, chromium stearate, chromium oleate, and chromium benzoate; chromium &bgr;-diketonates such as chromium tris(acetylacetonate), chromium tris(trifluoroacetylacetonate), chromium tris(hexafluoroacetylacetonate), chromium tris(benzoylacetonate), and chromium tris(2,2,6,6-tetramethyl-3,5-heptanedionate); chromium alkoxides or aryloxides such as chromium ethoxide, chromium isopropoxide, chromium 2-ethylhexoxide, chromium phenoxide, chromium nonylphenoxide, and chromium naphthoxide; and organochromium compounds such as tris(allyl)chromium, tris(methallyl)chromium, tris(crotyl)chromium, bis(cyclopentadienyl)chromium (also called chromocene), bis(pentamethylcyclopentadienyl)chromium (also called decamethylchromocene), bis(benzene)chromium, bis(ethylbenzene)chromium, and bis(mesitylene)chromium.
The organomagnesium compound employed in the catalyst system of the instant invention is a dihydrocarbyl magnesium compound or a hydrocarbon soluble Grignard reagent. The dihydrocarbyl magnesium compound is represented by the formula MgR
2
, where each R, which may be the same or different, is for example, an alkyl, cycloalkyl, aryl, aralkyl, or allyl group; each group preferably containing from 1 or the appropriate minimum carbon atoms to form such group up to 20 carbon atoms. Examples of such dihydrocarbyl magnesium compounds are diethyl magnesium, di-n-propyl magnesium, diisopropyl magnesium, dibutyl magnesium, dihexyl magnesium, diphenyl magnesium, and dibenzyl magnesium. Preferably, the organomagnesium compound is soluble in hydrocarbon polymerization medium. Dibutyl magnesium is particularly preferred on the grounds of availability and solubility. The hydrocarbon soluble Grignard reagent is represented by the formula RMgX where R is a hydrocarbyl group such as exemplified above and X is fluorine, chlorine, bromine or iodine. Included but not limited to this group of RMgX catalyst components are: ethylmagnesium bromide, butylmagnesium bromide, phenylmagnesium bromide, methylmagnesium chloride, butylmagnesium chloride, ethylmagnesium iodide, phenylmagnesium iodide and the like.
The dihydrocarbyl hydrogen phosphites employed in the catalyst system of the present invention may be represented by the following keto-enol tautomeric structures:
where R
1
and R
2
are alkyl, cycloalkyl, aryl, aralkyl, or allyl groups which may or may not be identical, each group prefe
Hall James E.
Kang Jung W.
Luo Steven X. L.
Ozawa Yoichi F.
Bridgestone Corporation
Burleson David G.
Retzer Aaron B.
Teskin Fred
Troy, Sr. Frank J.
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