Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Patent
1997-01-27
1998-05-26
Teskin, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
528481, 528502R, 528503, 264102, 26421123, 26433115, 264345, 264571, C08J 318
Patent
active
057566585
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for preparing a styrenic resin, and more specifically, it relates to a method for economically and efficiently decreasing a remaining volatile component such as an unreacted monomer in a styrenic polymer powder having a syndiotactic configuration, when the styrenic polymer powder is extruded.
BACKGROUND ART
A styrenic polymer (hereinafter abbreviated to "SPS" sometimes) having a syndiotactic configuration obtained by improving a styrenic polymer having an atactic configuration is excellent in heat resistance and chemical resistance.
The group of the present inventors has already succeeded in the development of a styrenic polymer having a high syndiotacticity, and this group has further disclosed that the SPS can be obtained by the use of a catalyst comprising a titanium compound, a catalytic product (an alkylaluminoxane) of an organic aluminum compound and a condensing agent, or a coordinated complex compound comprising a cation and an anion in which a plurality of groups are bonded to a metal (Japanese Patent Application Laid-open Nos. 187708/1987 and 249503/1992).
When the styrenic polymer having the syndiotactic configuration is prepared by a non-solvent polymerization method or a slurry method, about 0.1 to 50% by weight of a remaining volatile component such as an unreacted monomer is contained in the obtained polymer. In the case that a large amount of the unreacted monomer and the like remains in a product, molding failure occurs, and in films or the like, transparency deteriorates, and molded articles unsuitable for the packing of foods are formed sometime. Therefore, as a post-treatment subsequent to the polymerization, a drying devolatilization treatment using a drying machine is necessary to remove a remaining volatile component such as the monomer therefrom.
However, in the case that the removal of the remaining volatile component is made by the use of the drying machine, a residence time is prolonged, which is not economical.
On the other hand, even when devolatilization and extrusion are carried out by the use of an extruder, the efficiency of the devolatilization noticeably deteriorates, if a large amount of the volatile component is contained. This reason is that an apparent viscosity deteriorates owing to the volatile component contained in a material powder, so that shearing heat in the extruder is poor, with the result that the temperature in the extruder does not sufficiently rise, which disturbs the efficient removal of the volatile component. As a means for raising the temperatue, it can be contrived to increase the rotational frequency of the screw of the extruder.
However, when the rotational frequency of the screw is merely increased, the temperature noticeably rises owing to the shearing heat in a position where the volatile component is removed and the apparent viscosity is increased, so that the decomposition of the resin occurs on occasion.
DISCLOSURE OF THE INVENTION
Under such circumstances, the present inventors have intensively researched with the intention of developing a technique by which the above-mentioned problems can be solved, i.e., by which a remaining volatile component such as a monomer in a styrenic polymer powder having a syndiotactic configuration can economically and efficiently be decreased at the time of extrusion, whereby a molding material having a good shape and containing a less amount of the remaining volatile component can efficiently and stably be prepared to prevent the emission of a bad smell at the time of the extrusion or molding.
As a result, it has been found that the above-mentioned theme can be achieved by carrying out the extrusion under specific conditions by the use of an extruder. The present invention has been completed on the basis of the found knowledge.
That is to say, the first aspect of the present invention is directed to a process for preparing a styrenic resin which comprises the step of extruding a styrenic polymer powder having a syndiotactic configuration
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Fukada Kazuyoshi
Onodera Tsutomu
Saeki Takashi
Idemitsu Petrochemical Co. Ltd.
Teskin Fred
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