Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1996-07-25
1998-04-14
Teskin, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526132, 526133, 526148, 526151, 526159, 526160, 526161, 5263472, C08F 4642, C08F 1208
Patent
active
057392277
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for controlling molecular weight of a styrenic polymer. More particularly, the present invention relates to a process for efficiently controlling molecular weight of a styrenic polymer having the syndiotactic configuration.
BACKGROUND ART
Recently, production of a styrenic polymer having the syndiotactic configuration (referred to as SPS occasionally) with a considerably high yield has been enabled by polymerization of a styrenic monomer using a catalyst comprising a transition metal compound, particularly a titanium compound, and an alkylaluminoxane as the main components. However, when a polymer is produced by this process at a temperature of polymerization in such a range that the catalyst has a high activity, the produced polymer has a considerably high molecular weight, and development of a method for controlling the molecular weight of the produced polymer is required.
As the method for controlling the molecular weight, it was proposed that the molecular weight of the polymer could be decreased by increasing the temperature of polymerization.
However, the method of controlling the molecular weight by increasing the temperature of polymerization has drawbacks in that the catalyst activity is decreased to cause decrease in the productivity and increase in the production cost, and that the styrenic polymer having the atactic configuration is formed in an increasing amount to cause deterioration of the quality.
Therefore, it is desired to develop a process for controlling the molecular weight of the polymer which keeps decrease in the activity as small as possible at a temperature which does not cause formation of the styrenic polymer having the atactic configuration.
DISCLOSURE OF THE INVENTION
As the result of extensive investigations undertaken by the present inventors under the circumstances described above, it was discovered that, by adding an organometallic compound in the process for producing a styrenic polymer by using a transition metal compound, an aluminoxane or a coordinated complex compound composed of a cation and an anion in which a plurality of groups are connected to the metal, and an alkylating agent, the molecular weight of the formed styrenic polymer can efficiently be controlled. The present invention has been completed on the basis of the discovery.
Accordingly, the present invention provides a process for controlling molecular weight of a styrenic polymer comprising adding an organometallic compound in a process for producing a crystalline styrenic polymer having a highly syndiotactic configuration by using a catalyst for producing a styrenic polymer having the syndiotactic configuration.
THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION
In the process of the present invention, a styrenic monomer is polymerized by using a catalyst for producing a styrenic polymer having the syndiotactic configuration. As the catalyst for polymerization, various types of catalyst effective for producing SPS can be used. For example, a styrenic monomer is polymerized in the presence of a catalyst for polymerization which comprises (a) a transition metal compound, (b) a coordinated complex compound composed of a cation and an anion in which a plurality of groups are connected to a metal or an aluminoxane and/or (c) an alkylating agent.
As the transition metal compound of the component (a) used in the present invention, a compound represented by the following general formula (1) or (2): metal of the lanthanoid series of the Periodic Table, R.sup.1, R.sup.2, R.sup.3, and R.sup.4 represent each an alkyl group, an alkoxy group, an aryl group, cyclopentadienyl group, an alkylthio group, a substituted cyclopentadienyl group, indenyl group, a substituted indenyl group, a fluorenyl group, a halogen atom, amino group, or a chelating agent, a, b, and c represent each an integer of 0 to 4, d and e represent each an integer of 0 to 3, and two groups selected from R.sup.1 to R.sup.4 may be crosslinked to each other through CH.sub.2 or Si(
REFERENCES:
patent: 5066741 (1991-11-01), Campbell, Jr.
patent: 5340892 (1994-08-01), Kuramoto
patent: 5428120 (1995-06-01), Newman et al.
Teshima Hideo
Tomotsu Norio
Idemitsu Kosan Co. Ltd.
Teskin Fred
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