Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-02-03
2002-05-21
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S164000, C526S335000, C526S336000, C526S337000, C526S338000, C526S339000, C526S340000
Reexamination Certificate
active
06391990
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of producing a conjugated diene polymer, and more particularly to a method of producing a conjugated diene polymer which can provide polymers having sufficiently controlled molecular weight and molecular weight distribution and excellent mechanical properties, thermal properties and the like by using a catalyst of a lanthanoid compound having a high polymerization activity and a hydrocarbon solvent containing an aromatic hydrocarbon as a polymerization solvent to control a polymerization rate and conduct continuous polymerization. Further, the invention relates to a method of producing a conjugated diene polymer capable of providing polymers having an excellent wear resistance, a reduced cold flow and the like by reacting and modifying the above obtained conjugated diene polymer with a particular compound.
2. Description of Related Art
Since the conjugated diene polymers play an industrially very important role, there have hitherto been proposed many proposals for a polymerization catalyst of a conjugated diene monomer in the production of the conjugated diene polymer. Particularly, many polymerization catalysts giving a high content of cis-1,4-bond have been developed for providing conjugated diene polymers having excellent mechanical and thermal properties. For example, there is well-known a composite catalyst system containing a compound of a transition metal such as nickel, cobalt, titanium or the like as an essential component. Among them, some catalysts have industrially and widely been used as a polymerization catalyst of butadiene, isoprene or the like (see End. Ing. Chem., 48, 784(1956) and JP-B-37-8198).
On the other hand, in order to obtain polymers having a higher content of cis-1,4-bond, there has been studied and developed a high stereospecific polymerization using a composite catalyst system comprising a rare earth metal compound and an organometal compound of an element of Group I-III and having a higher activity (Makromol. Chem. Suppl., 4, 61 (1981), J. Polym. Sci. Polym. Chem. Ed., 18, 3345 (1980), German Patent Application No. 2,848,964, Sci. Sinica., 23, 734 (1980), Rubber Chem. Technol., 68, 117 (1985) and the like).
Among these catalyst systems, it has been confirmed that a composite catalyst containing a neodymium compound and an organoaluminum compound as an essential component has an excellent polymerization activity and provides a polymer having a high content of cis-1,4-bond, which has already been industrialized as a polymerization catalyst for butadiene or the like (Macromolecules, 15, 230 (1982), Makromol. Chem., 94, 119 (1981) and the like). However, the demand for high polymer materials in market is more increasing with the advance of recent industrial technique and hence it is required to develop conjugated diene polymers having excellent mechanical properties such as wear resistance and the like and thermal properties such as thermal stability and the like.
In order to solve the above problem, there are made studies with respect to a polymerization method capable of providing polymers having a narrow molecular weight distribution by using a catalyst having a further higher activity. For example, it is reported that the polymerization activity becomes high when using a two-component catalyst system consisting of a neodymium compound and methylaluminoxane (Polymer Communication, 32, No. 17, p514 (1991) and the like). And also, it is reported that a catalyst system obtained by adding an organoaluminum compound and/or Lewis acid to the system of the neodymium compound and aluminoxane is high in the polymerization activity and provides a conjugated diene polymer having a narrow molecular weight distribution (JP-A-6-211916, JP-A-6-306113, JP-A-8-73515 and the like). However, when using these catalysts, the resulting polymer is generally a straight chain polymer being less in the branched structure, so that it is difficult to mix such a polymer with another high polymer material such as rubber or various fillers, or there is a problem in the processability and the cold flow becomes large to cause a problem in the storage and transportation.
In JP-A-63-178102, JP-A-630297403, JP-A-63-305101, JP-A-5-51406, JP-A-5-59103 and the like is report that the conjugated diene monomer is polymerized by using the catalyst system of neodymium compound and organoaluminum compound and reacted with a particular compound as a modifying agent to provide a polymer having an improved processability. In this catalyst system, however, the polymerization activity can not be said to be a sufficiently satisfactory high level.
DESCRIPTION OF THE INVENTION
It is an object of the invention to provide a method of producing a conjugated diene polymer having a narrow molecular weight distribution and excellent mechanical and thermal properties by using a catalyst system comprising a lanthanoid compound and aluminoxane and having a high polymerization activity and a polymerization solvent including an aromatic hydrocarbon to conduct continuous polymerization while controlling a polymerization rate.
It is another object of the invention to provide a method of producing a conjugated diene polymer capable of reacting the above obtained polymer with a particular compound to provide conjugated diene polymer having further excellent mechanical properties such as wear resistance and the like and reducing cold flow or the like to facilitate storage, transportation and the like.
According to the invention, there is the provision of a method of producing a conjugated diene polymer which comprises continuously polymerizing a conjugated diene monomer with a catalyst consisting essentially of the following components (1) to (3) in a hydrocarbon solvent containing 5-50% by weight of an aromatic hydrocarbon to obtain a conjugated diene polymer having a ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of not more than 4:
Component (1): a lanthanoid compound;
Component (2): an aluminoxane; and
Component (3): a halogenated organometal compound, a halogenated metal compound or a halogenated organic compound having at least one of chlorine atom, bromine atom and iodine atom.
As the hydrocarbon solvent, use may be made of a saturated alicyclic hydrocarbon such as cyclopentane, cyclohexane or the like; a saturated aliphatic hydrocarbon such as butane, pentane, hexane, heptane or the like; and so on. And also, the hydrocarbon solvent contains 5~50% by weight, preferably 10~40% by weight, more particularly 15~35% by weight of the aromatic hydrocarbon. As the aromatic hydrocarbon, use may be made of toluene, xylene, benzene and so on. Particularly, toluene is preferable because it is low in the solidification point and can be used even at a low temperature and hardly remains in the resulting polymer. When the amount of the aromatic hydrocarbon is less than 5% by weight, the polymerization rate can not sufficiently be controlled, while when it exceeds 50% by weight, the polymerization rate is too small.
As the conjugated diene monomer, mention may be made of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, cyclo-1,3-pentadiene and so on. Particularly, polymer made from 1,3-butadiene and isoprene is useful. These conjugated diene monomers may be used alone or in admixture of two or more monomers. When two or more monomers are used, a copolymer is obtained.
The production of the conjugated diene polymer according to the first aspect of the invention is carried out by the continuous polymerization. The term “continuous polymerization” used herein means that the catalyst is always fed into the reaction system and is existent at an active state. The concentration of the catalyst is not particularly restricted because the molecular weight distribution and the like of the resulting polymer can be controlled even at the high concentration or low concentration. And also, the continuous polymerization may be carried out by a single reactor but also pl
Hattori Iwakazu
Ishino Yoshiki
Mori Yoshihiro
Nakayama Satoshi
JSR Corporation
Lipman Bernard
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