Scg Chemicals Company Limited

Thai Polyethylene Co., Ltd.

Mitsui Chemicals, Inc.

Patcharin Samphawamontri

Warachad Klomkamol

Natthaporn Suchao-In

Shinichi Kojoh

Eiji Shiba

Watcharee Cheevasrirungruang

Kenji Iwamasa

Piyawan Tiyapiboonchaiya

Yasunori Kaneko

Takashi Fukawa

Thipphaya Pathaweeisariyakul

Thippaya Pathaweeisariyakul

The present invention relates to a process for producing a multimodal polyethylene composition in the reactor system according to the invention, comprising; (a) polymerizing ethylene in an inert hydrocarbon medium in the first reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and hydrogen in an amount of 0.1-95% by mol with respect to the total gas present in the vapor phase in the first reactor to obtain a low molecular weight polyethylene or a medium molecular weight polyethylene; (b) removing in the hydrogen removal unit 98.0 to 99.8% by weight of the hydrogen comprised in a slurry mixture obtained from the first reactor at a pressure in the range of 103-145 kPa (abs) and transferring the obtained residual mixture to the second reactor; (c) polymerizing ethylene and optionally Cto Cα-olefin comonomer in the second reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and in the presence of hydrogen in an amount obtained in step (b) to obtain a first high molecular weight polyethylene or a first ultra high molecular weight polyethylene in the form of a homopolymer or a copolymer and transferring a resultant mixture to the third reactor; and (d) polymerizing ethylene, and optionally α-olefin comonomer in the third reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and hydrogen, wherein the amount of hydrogen in the third reactor is in a range of 1-70% by mol, preferably 1-60% by mol with respect to the total gas present in the vapor phase in the third reactor or optionally substantial absence of hydrogen to obtain a second high molecular weight polyethylene or a second ultra high molecular weight polyethylene homopolymer or copolymer; and a multimodal polyethylene composition obtainable this way.

Reactor system for multimodal polyethylene polymerization

The present invention relates to a bimodal polyethylene composition comprising a low molecular weight polyethylene homopolymer fraction and high molecular weight polyethylene copolymer fraction having a Cto C&#x3b1;-olefin comonomer content of 0.25 to 3% mol with respect to the total monomer comprised in the high molecular weight polyethylene comonomer fraction, wherein the content of the low molecular weight polyethylene is from 50 to 60 wt % with respect to the total weight of the bimodal polyethylene composition; and the bimodal polyethylene composition has a soluble fraction according to Temperature Rising Elution Fractionation in 1,2,4-trichlorobenzene with 300 ppm of butylated hydroxytoluene at 150&#xb0; C. of less than 6 wt %; and a pipe comprising the same.

Bimodal polyethylene composition and pipe comprising the same

The pipe articles with excellent stress crack resistance can be achieved by providing ethylene copolymer composition comprises ethylene and a C6-C10 &#x3b1;-olefin comonomer; the ethylene copolymer having a total density of 0.945-0.980 g/cmand a MFRof 0.10-0.50 g/10 min; and the ethylene copolymer having a comonomer content of 1-5% wt. The ethylene copolymer has M/Min the range of not less than 14.0; gpcBR in the range of from 0.20 to 0.80; and strain hardening modulus &#x3c;Gp&#x3e; in the range of not less than 53.4.

Ethylene copolymer composition

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Bangkok, Thailand

Patcharin Samphawamontri