Showa Denko K.k.

Japan Polyolefins Co., Ltd.

Japan Polyethylene Corporation

Hidenobu Torigoe

Takashi Monoi

Masakazu Yamamoto

Shintaro Inazawa

Yoshimitsu Ishihara

Yasunori Takemoto

Haruhiko Ikeda

Shigeki Saito

A method for producing an ethylene polymer which comprises continuously polymerizing ethylene alone or copolymerizing ethylene and a C-C&#x3b1;-olefin by multistage polymerization in a plurality of polymerization reactors connected in series in the presence of a chromium catalyst having at least a part of chromium atoms converted to hexavalent chromium carried on an inorganic oxide carrier by calcination-activating in a non-reducing atmosphere, wherein an organoaluminum compound of the formula (1):(R)Al(OR)(OSiRRR)&#x2003;&#x2003;(1)(in the above formula, Rand Rmay be the same or different, each represents a C-Calkyl group or a C-Caryl group, R, Rand Rmay be the same or different, each represents a C-Calkyl group or a C-Caryl group, R, ORand OSiRRRrespectively may be the same or different when each has a plurality of kinds, and x, y and z are respectively 0&#x2266;x&#x2266;3, 0&#x2266;y&#x3c;3, 0&#x2266;z&#x3c;3, and x+y+z=3) is introduced at least one or all of the polymerization reactors.

Ethylene polymer, catalyst for producing thereof and method for producing thereof

The invention relates to a method for producing an ethylene polymer, comprising performing polymerization of ethylene in co-presence of hydrogen using a trialkylaluminum compound-carried chromium catalyst, wherein the chromium catalyst is obtained by calcination-activating a chromium compound that is carried on an inorganic oxide carrier in a non-reducing atmosphere to convert chromium atoms in the chromium compound into hexavalent chromium atoms for at least a portion thereof, and treating with a trialkylaluminum compound in an inert hydrocarbon solvent to carry thereon and removing to dry the solvent so that the chromium atoms are not over-reduced by the trialkylaluminum compound, and to an ethylene polymer suitable for blow molded articles obtained by the production method. The ethylene polymer of the invention have improved environment stress crack resistance (ESCR) and impact resistance in a good balance and are suitable for molded blow articles, in particular large size blow molded articles.

Ethylene polymers and method for producing the same

A catalyst for the production of an ethylene polymer comprising a specific trivalent alkyl chromium compound, an inorganic oxide solid and optionally an organoaluminum compound (first catalyst), a catalyst for the production of an ethylene polymer comprising the specific trivalent alkyl chromium compound, a specific tetravalent alkyl chromium compound and an inorganic oxide solid (second catalyst) and a process for producing an ethylene polymer using those catalysts. The first catalyst of the present invention does not cause deterioration with the passage of time, is stable to heat and light, has greatly improved activity and can efficiently produce an ethylene copolymer with &agr;-olefin. The second catalyst of the present invention can efficiently produce an ethylene polymer having low molecular weight and narrow molecular weight distribution suitable for use in injection molding or an ethylene polymer having excellent balance between rigidity and ESCR and also excellent moldability suitable for use in blow molding or film molding.

Catalyst for the production of ethylene polymer and process for producing ethylene polymer

Process for preparing ethylene polymer and catalyst used therefor

Ethylenic polymers and process for the production thereof

Preparation method of ethylene base polymer

A process for the production of ethylenic polymers is disclosed in which an ethylenic monomer is polymerized in the presence of a catalyst comprising a chromium compound, an alumoxane and an organometallic alkoxide and/or organometallic siloxide and a carrier supporting thereon these compounds. The resultant polymer has a balanced proportion of rigidity and environmental stress cracking resistance (ESCR) and an excellent moldability property.

Process for the production of ethylenic polymers

Growing community of inventors

Oita, Japan

Hidenobu Torigoe