Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1996-01-02
1998-05-05
Teskin, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526126, 526128, 526133, 526135, 526142, 526144, 526160, 526164, 526170, 526347, C08F 480, C08F21002
Patent
active
057476136
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing an aromatic vinyl compound-based copolymer. More particularly, it pertains to a process for efficiently producing an aromatic vinyl compound-based copolymer which is minimized in residual amounts of ash and toxic substances, maintains polymer performance at a high temperature and has a high degree of syndiotactic configuration in its aromatic vinyl chain by the use of a catalyst which has a high activity and favorable copolymerization properties and is free from deterioration of activity due to the by-production of a Lewis base such as an amine, while dispensing with an expensive aluminoxane.
BACKGROUND ART
It is known that olefinic polymers are produced in the presence of a catalyst system comprising Ziegler-Natta catalyst as a principal component. In recent years in particular there have been observed a number of processes for producing olefinic polymers in the presence of a soluble type catalyst comprising a transition metal compound and an aluminoxane as a co-catalyst. However, the aluminoxane, especially a highly active methylaluminoxane suffers the disadvantages that trimethylaluminum as a starting raw material is expensive and causes danger in the production process of an aluminoxane with the results that a methylaluminoxane becomes an expensive compound, and in a catalyst system containing the methylaluminoxane as a co-catalyst, a large amount of the aluminoxane is required in comparison with an transition metal compound, thereby inevitably increasing the production cost of the polymer.
With regard to a polymerization catalyst system without the use of such an expensive aluminoxane, it is reported that a metallocene cation complex which is formed by bringing a neutral metallocene into contact with an ionic compound containing an iron (III) cation possesses polymerization American Chemical Society (J. Am. Chem. Soc.) vol 108, page 7410 (1987)!. In the above-mentioned system in which an ionic compound containing a cation of iron (III) is used as an ionizing agent for the metallocene, a metallocene cation complex is formed by drawing a ligand through the utilization of the oxidation-reduction performance of an iron (III) cation with the reaction formula exemplified by the following. Fe is a metal and A is an anion.
When the above-mentioned reaction is put into practice under a polymerizaiton condition, a compound originating from the iron III cation remains in the resulting resin after the polymerization. The compound is sometimes responsible for the coloration of the resulting resin, thus impairing the properties inherent to the resin.
There is also disclosed a protonation method as an ionization method of a metallocene. (Refer to European Patent No. 277004.) This is a method for forming a metallocene cation by allowing a metallocene having a group capable of reacting with a proton to react with an ammonium salt having an active proton with the reaction formula exemplified by the following.
There is formed in this reaction, as a by-product, a Lewis base (that is, an amine such as R.sub.3 N), which can be coordinated with the metallocene cation, thus deteriorating the catalytic activity. In addition, both the catalyst and a resin produced in the presence of the catalyst contain a toxic residual amine.
There is further disclosed a process for producing a metallocene cation by bringing an ionized ionic compound into contact with a neutral metallocene. (Refer to European Patent No. 426637.) By the term ionized ionic compound as used herein is meant an ionic compound containing a cation without an active proton, which compound is exemplified a by triphenylcarbenium cation.
In this reaction, as exemplified by the following reaction formula, a ligand is drawn from a metallocene by a carbenium ion to form a metallocene cation. group.
In the aforesaid case, the by-produced Ph.sub.3 C--R is a polymerization solvent-like compound.
The conventional carbenium compound, however, is not highly soluble in a solvent with a low polarity which
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Shouzaki Hajime
Takeuchi Mizutomo
Tomotsu Norio
Idemitsu Kosan Co. Ltd.
Teskin Fred
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