Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1996-12-24
1998-10-20
Teskin, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526133, 526153, 526160, 526346, 526905, C08F 238, C08F 4642
Patent
active
058247530
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing a styrenic polymer. More particularly, the present invention relates to a process for producing a styrenic polymer having the syndiotactic configuration which enables decrease in the amount of the catalyst, decrease in the amount of residual metals, and decrease in the cost of production.
BACKGROUND ART
Recently, a process for producing a styrenic polymer having the syndiotactic configuration (hereinafter, this polymer is occasionally referred to as SPS) by using a catalyst comprising a transition metal compound, particularly a titanium compound, and an alkylaluminoxane as the main components thereof has been proposed (the specifications of Japanese Patent Application Laid-Open No. Showa 62(1987)-187708, and other related applications).
In order to produce a styrenic polymer having the syndiotactic configuration efficiently in the above process without using the alkylaluminoxane which is expensive and used in a large amount, a process using a coordinated complex compound comprising an anion having a plurality of groups bonded to a metal and a cation has also been proposed (the specifications of Japanese Patent Application Laid-Open Nos. Heisei 2(1990)-415573 and Heisei 2(1990)-415574).
In the above process of polymerizing a styrenic monomer by using a transition metal and an aluminoxane, introduction of hydrogen into the polymerization system as the agent for molecular weight control has been proposed in order to control the molecular weight (the specification of Japanese Patent Application Laid-Open No. Showa 63(1988)-179906).
However, when a coordinated complex compound comprising an anion having a plurality of groups bonded to a metal and a cation is used in place of an aluminoxane because the aluminoxane is expensive and causes a low yield, the polymerization temperature is increased or an alkylaluminum is added in a large amount as an agent for molecular weight control. This causes drawbacks in that the yield of the obtained SPS is decreased and that the amount of residual metals is increased.
When the molecular weight distribution is controlled by increasing the temperature during the polymerization, drawbacks are found in that the yield of SPS is decreased and that the cost of the catalyst is increased.
In the specification of Japanese Patent Application Laid-Open No. Heisei 3(1991)-119006, a process in which a plurality of titanium catalysts are used has been disclosed. In the specification of Japanese Patent Application Laid-Open No. Heisei 6(1994)-116328, a process in which two different types of cocatalyst component and an organoaluminum component are added has been disclosed. However, the processes disclosed in the above specifications have drawbacks in that two or more types of transition metal complex compound are required and that the amount of residual aluminum is increased, and it is difficult that the molecular weight distribution is efficiently controlled by these processes.
DISCLOSURE OF THE INVENTION
As the result of the extensive studies conducted by the present inventors under the above circumstances to enable the efficient control of the molecular weight and the molecular weight distribution and to decrease the cost of production in the process for producing the styrenic polymer, it has been discovered that the amount of the catalyst and the amount of residual metals are decreased and the cost of production is also decreased by increasing the activity of the catalyst and that the molecular weight distribution can be controlled by adding hydrogen after the polymerization of styrene has started or by changing the amount of supplied hydrogen. The present invention has been completed on the basis of the discovery.
Accordingly, the present invention provides a process for producing a styrenic polymer having the syndiotactic configuration which process comprises a plurality of polymerization stages, at least one polymerization stage selected as desired from the plurality of polymerization stages being a polyme
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Naganuma Shoji
Tomotsu Norio
Idemitsu Kosan Co. Ltd.
Teskin Fred
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