Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1996-06-28
1998-04-14
Wu, David W.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526160, 526161, 5261691, 5261692, 526282, 526335, 526336, 526340, 5263482, 5263483, 5263484, 5263485, 5263486, 526943, 502117, 502155, C08F 464
Patent
active
057392250
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a novel process for preparing an olefin polymer, and an ethylenic polymer. More specifically, the present invention relates to a process for preparing an olefin homopolymer or an olefin copolymer very economically advantageously in which even if the amount of an expensive aluminum compound as a promotor is small, the homopolymerization or the copolymerization of an olefin can be carried out by the use of a polymerization catalyst having a high activity and an excellent copolymerizability to permit the omission of deashing and washing steps and to reduce the influence of the remaining catalyst on product quality and in which when the copolymerization is carried out, the conversion of a comonomer is high, and hence, after the completion of the polymerization, the collection of the comonomer component is unnecessary or the comonomer can be removed in a simple manner. In addition, the present invention also relates to an ethylenic polymer having high melt flow properties, an excellent molding stability (swell ratio), good mechanical properties (such as tearing strength), good heat-sealing properties and a good ESCR (environmental stress crack resistance).
BACKGROUND ART
Heretofore, an olefin polymer such as a polyethylene or an ethylene-.alpha.-olefin copolymer has been manufactured in the presence of a transition metal catalyst such as a titanium catalyst comprising a titanium compound and an organic aluminum compound, or a vanadium catalyst comprising a vanadium compound and the organic aluminum compound.
In recent years, as examples of such a transition metal catalyst, there have newly been suggested many zirconium catalysts each comprising a zirconium compound and an aluminoxane by which ethylene can be copolymerized with an .alpha.-olefin under a high polymerization activity. However, such zirconium catalysts have a drawback that a large amount of the expensive aluminoxane must be used.
On the other hand, with regard to the polyethylene or the ethylene-.alpha.-olefin copolymer, its primary structure has heretofore been controlled by adjusting a molecular weight, a molecular weight distribution or copolymerization properties (random properties, a blocking tendency and a composition distribution), or by adding a third component such as a diene so as to introduce branches.
For ethylenic polymers, various molding methods are usable, and typical known examples of the molding methods include injection molding, extrusion, blow molding, inflation, compression molding and vacuum forming. In such molding methods, the impartment of high-speed molding properties and the reduction of molding energy have been investigated for a long period of time in order to improve working properties and to thus lower a working cost, and so it is an important theme that optimum physical properties suitable for each use are imparted and the molding can be carried out with the optimum working properties.
In recent years, it has been elucidated that a uniform metallocene catalyst is excellent in the copolymerization properties between olefins, can obtain a polymer having a narrow molecular weight distribution, and has a much higher catalytic activity as compared with a conventional Vanadium catalyst. Therefore, it has been expected that the metallocene catalyst will be developed in various technical fields by the utilization of such characteristics. However, a polyolefin obtained by the use of the metallocene catalyst is poor in molding and working properties, and for this reason, the application of the metallocene catalyst to the blow molding and the inflation is unavoidably limited.
Thus, various olefin polymers, into which longchain branches are introduced in order to solve such problems, have been disclosed. For example, there have been disclosed (1) an olefin copolymer having the long-chain branches obtained by the use of an .alpha.,.omega.-diene or a cyclic endomethylenic diene (Japanese Patent Application Laid-open No. 34981/1972), (2) a process for preparing a copolymer contai
REFERENCES:
patent: 5444134 (1995-08-01), Matsumoto
Soga et al, "Recent Development In Stereochemical Control Of Heterogeneous Ziegler-Natta Catalysts", Makromolekulare Chemie, Macromolecular Symposia, vol. 63, Oct. 1, 1992, pp. 219-231.
Chein et al, "Metallocene-Methylaluminoxane Catalysts for Olefin Polymerization. V. comparsion of Cp.sub.2 ZrCl.sub.2 and CpZrCl.sub.3," Journal of Polymer Science, Polymer Chemistry Edition, vol. 28, No. 1, Jan. 15, 1990, pp. 15-38.
Kadoi Yasunori
Kawasaki Nobuo
Machida Shuji
Nakacho Kenji
Shikuma Haruo
Idemitsu Kosan Co. Ltd.
Wu David W.
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