Process for preparing and using neodymium neodecanoate

Details Process for preparing and using neodymium neodecanoate Process for preparing and using neodymium neodecanoate

2000-05-16

2002-11-19

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...

C526S335000, C526S159000, C502S263000

Reexamination Certificate

active

06482906

ABSTRACT:

FIELD OF THE INVENTION
The present application refers to a process for the preparation of neodymium neodecanoate, to the process for the preparation of a homogeneous coordination catalytic system composed of three components, of which the metal compound is the neodymium neodecanoate, to the process for the solution polymerization of butadiene for the preparation of polybutadiene with a high content of the 1,4-cis isomer, and to the elastomeric products manufactured from this polymer, particularly tires for the automotive industry.
BACKGROUND OF THE INVENTION
During the last years, saving energy and protecting the environment have become priorities of society. The market requires more and more low fuel consumption vehicles and rubber components of higher durability and wear resistance. These requirements may be satisfied through the use of tires with low resistance to rolling and higher resistance to abrasion.
Products derived from butadiene are being largely produced on an industrial scale, especially polybutadiene with a high content of the 1,4-cis form, which exhibits excellent properties for application in the manufacture of tires for the automotive industry, like abrasion resistance, fatigue resistance, tear resistance, low heat build-up and low rolling resistance.
Physical and mechanical properties of polybutadienes, as well as their ease of processing, depend on the microstructure and the microstructure displayed by these polymers. Thus, molecular weight, molecular weight distribution, polydispersion, branching index, and cis content are the major responsible factors for the performance of these polymers.
The microstructure of polybutadienes, especially the content of 1,4-cis units, influences significantly the physical properties of the pure gum and the vulcanized products. However, they do not vary significantly in the range between 25 and 80 percent of the 1,4-cis units, but change rapidly beyond these limits. This is because polybutadienes have the capacity to crystalize under pressure, improving the physical properties of the polymer. This effect increases as the content of 1,4-cis units is raised. Thus intensive research is being carried out to develop new catalytic systems that are able to produce polymers with high stereospecificity by polymerization of conjugated dienes.
Great advances have been achieved, not only in the invention of new catalytic systems, but also in the development of new polymerization processes, that yield products with controlled molecular weight, distribution of molecular weight, branch content and microstructure.
Polybutadiene may be produced by different polymerization mechanisms. However, only the coordination catalysts make it possible to achieve a high degree of chemical and steric selectivity during the polymerization process.
Polybutadiene with a high content of 1,4-cis units may be prepared using stereospecific catalysts of the Ziegler-Natta type, based on organometallic complexes of transition metals. The commercially available technologies for the manufacture of this elastomer utilize solution processes and organometallic complexes based on cobalt, titanium, nickel, and rare earths.
The production systems of high cis polybutadiene based on titanium, cobalt, and nickel have some drawbacks. Firstly, it is necessary to use aromatic solvents, because these solvents favor the rate of polymerization, the yields, the cis content, and the molecular weight. However, aromatic solvents are more toxic, and generally more expensive than aliphatic solvents. Secondly, it is necessary to work at low polymerization temperatures in order to favor the formation of the 1,4-cis isomer. This requires sophisticated cooling systems of high investment cost. Thirdly, the conversion yields are below 90%, which entails a loss of productivity and an increase of investment and operational costs, since an additional stage for recovery of non-reacted monomer becomes necessary.
With relation to the polymer's properties, products resulting from technologies based on nickel, titanium, and cobalt exhibit mechanical properties that are inferior to the ones presented by polymers obtained via rare earths, especially properties such as tear resistance, fatigue resistance, abrasion resistance and heat build up. The polymers obtained from the use of rare earths show better processability, especially tack, green strength, and mill banding.
The European patent EP 406,920 mentions the use of catalytic systems containing metallic components of the rare earths series in the preparation of rubbers with excellent qualities.
The American U.S. Pat. No. 4,461,883, describes ternary catalytic systems consisting of NdCl
3
(neodymium chloride), an alcohol and triethylaluminum, which present serious disadvantages during industrial application. This is because NdCl
3
is solid and insoluble in an inert hydrocarbon, and the product of the reaction between the NdCl
3
and the alcohol is a precipitate that is insoluble in a hydrocarbon solvent, thus generating heterogeneous systems. Heterogeneous systems lead to wider polymer polydispersion, difficult control of molecular weight, and difficult reproductibility, when compared to homogeneous systems.
The Brazilian patent application PI 7804950 describes the use of monovalent and monodented chelates of rare earth metals and the American U.S. Pat. No. 3,297,667, the use of rare earth metals chelates with monovalent bidented or bivalent bidented binders in the catalytic systems. The American U.S. Pat. No. 4,242,232 states that chelate catalysts are solid substances that do not dissolve either in the monomer or in the solvents that are appropriate for polymerization processes. The products obtained by polymerization with these catalysts in the presence of organic solvents have the appearance of swollen agglomerates. The patent also discloses known catalysts consisting of (1) a rare earth salt of a carboxylic acid, (b) a trialkylaluminum, and (c) a Lewis acid, but that rare earth carboxylates are only slightly soluble in hydrocarbons and form highly viscous masses with them, even at high dilutions. However, the reaction of carboxylates with trialkylaluminum, according to the disclosure of the aforementioned patent, has solved the problem of their solubility.
The American U.S. Pat. No. 4,242,232 refers to the catalyst, to its preparation procedure, and to its application to the solution polymerization of conjugated dienes. This catalytic system differs from the one described in the prior art by the use of Lewis acids. The Lewis acids utilized are the organometallic halides of metals pertaining to the groups IIIA or IVA of the Periodic Table, and the halides of elements of the groups IIIA, IVA, and VA of the Periodic Table. The order of addition of the catalytic components is indifferent, and the reaction proceeds over a wide temperature range, which is generally limited by the boiling point of the solvent used. Polymerization occurs at temperatures that vary from 0° to 120° C.
The American U.S. Pat. No. 4,461,883 declares that the product of the reaction between the neodymium carboxylate and the trialkylaluminum is difficult to handle, since it is extremely sensitive to the presence of humidity and oxygen, which cause the deactivation of part of the catalyst, lowering the yield of polymerization. The U.S. Pat. No. 4,461,883 refers to the process for the production of polymers of conjugated dienes utilizing a catalytic system containing a soluble lanthanide carboxylate, obtained by reaction of the carboxylate with a Lewis base. The Lewis bases utilized are, for example, acetylacetone, tetrahydrofuran, pyridine, monohydric and dihydric alcohols, containing from 1 to 10 carbon atoms. The catalytic system contains, besides the metallic component, an organic compound of aluminum and an alkylaluminum halide. In the preparation process of the catalyst, the compound with the lanthanide series metal is made to react initially with the Lewis base, at temperatures from −50° to 150° C., and, subsequently, the reaction product is reacted with the

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