Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1998-09-22
2000-11-28
Wu, David W.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526 86, 526 87, 526160, 526133, 526351, 526352, 526904, 526943, 502104, 502117, 502152, 525240, 525247, C08F 200, C08L 2316, B01J 3106
Patent
active
061537101
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a preactivated catalyst for olefin (co)polymerization that can produce an olefin (co)polymer having a high melt tension, a high crystallization temperature and excellent heat stability, and a catalyst for olefin (co)polymerization. The present invention also relates to an olefin (co)polymer composition having a high melt tension, a high crystallization temperature and excellent heat stability, and a method for producing the same.
BACKGROUND ART
Olefin (co)polymers such as polypropylene and polyethylene are widely used in a variety of molding fields because of their excellent mechanical properties, chemical resistance and cost-effectiveness. Conventionally, the olefin (co)polymers generally have been produced by (co)polymerizing olefin by using a so-called Ziegler-Natta catalyst, which is obtained by combining titanium trichloride or titanium tetrachloride, or a transition metal catalyst component comprising titanium trichloride or titanium tetrachloride supported by a carrier such as magnesium chloride, and an organic aluminum compound.
In recent years, on the other hand, a catalyst that is obtained by combining metallocene and aluminoxane, which is different from catalysts in the prior art, is used to (co)polymerize olefins to obtain olefin (co)polymers. The olefin (co)polymer obtained by using the metallocene-based catalyst has a narrow molecular weight distribution, and in the case of copolymers, comonomers are copolymerized uniformly. Therefore, it is known that more homogeneous olefin (co)polymers can be obtained than in the prior art. However, compared with olefin (co)polymers obtained by using a conventional catalyst type, the olefin (co)polymers obtained by using the metallocene-based catalyst have a lower melt tension, so that they are not suitable for some uses.
In order to enhance the melt tension and the crystallization temperature of polypropylene, the following methods have been proposed: a method of reacting polypropylene with an organic peroxide and a crosslinking assistant in a molten state (Japanese Laid-Open Patent Publication (Tokkai-Sho) Nos. 59-93711, 61-152754); and a method for producing gel-free polypropylene with free-end long chain branching by reacting semi-crystalline polypropylene with a peroxide having a low decomposition temperature in the absence of oxygen (Japanese Laid-Open Patent Publication (Ibkkai-Hei) No.2-298536).
Other methods for enhancing melting viscoelasticity such as melt tension have been proposed, such as a method of using a composition comprising polyethylenes or polypropylenes having different intrinsic viscosities or molecular weights, or producing such compositions by multistage polymerization.
Examples of such a method include a method in which 2 to 30 parts by weight of ultra high molecular weight polypropylene are added to 100 parts by weight of ordinary polypropylene and extrusion is performed in a temperature range from a melting point to 210.degree. C. (Japanese Patent Publication (kko-Sho) No. 61-28694), a method using multistage polymerization to obtain an extrusion sheet formed of two components of polypropylene having different molecular weights and a limiting viscosity ratio of at least 2 (Japanese Patent Publication (Ibkko-Hei) No. 1-12770), a method of producing a polyethylene composition formed of three types of polyethylene having different viscosity average molecular weights comprising 1 to 10 wt % of high viscosity average molecular weight polyethylene by melting and kneading or multistage polymerization (Japanese Patent Publication (Ibkko-Sho) No. 62-61057), a method for polymerizing polyethylene in which ultra high molecular weight polyethylene having an intrinsic viscosity of 20 dl/g or more is polymerized in an amount of 0.05 or more and less than 1 wt % by multistage polymerization with highly active titanium vanadium solid catalyst component (Japanese Patent Publication (Iokko-Hei) No. 5-79683), and a method for polymerizing polyethylene in which 0.1 to 5 wt % of ultra high molecu
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Kageyama Akiko
Kikukawa Shingo
Saito Jun
Tsutsui Mototake
Ushioda Tsutomu
Chisso Corporation
Harlan R.
Wu David W.
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