US 11,866,521 B2
Reactor system for multimodal polyethylene polymerization
Piyawan Tiyapiboonchaiya, Bangkok (TH); Patcharin Samphawamontri, Bangkok (TH); and Warachad Klomkamol, Bangkok (TH)
Assigned to Thai Polyethylene Co., Ltd, Bangkok (TH); and SCG Chemicals Co., Ltd., Bangkok (TH)
Appl. No. 16/332,006
Filed by Thai Polyethylene Co., Ltd., Bangkok (TH); and SCG Chemicals Co., Ltd., Bangkok (TH)
PCT Filed Sep. 7, 2017, PCT No. PCT/EP2017/072477
§ 371(c)(1), (2) Date Mar. 11, 2019,
PCT Pub. No. WO2018/046604, PCT Pub. Date Mar. 15, 2018.
Claims priority of application No. 16188318 (EP), filed on Sep. 12, 2016.
Prior Publication US 2023/0192913 A1, Jun. 22, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. C08F 10/02 (2006.01); C08F 2/00 (2006.01); C08F 2/18 (2006.01); C08F 2/01 (2006.01); C08L 23/08 (2006.01)
CPC C08F 10/02 (2013.01) [C08F 2/001 (2013.01); C08F 2/01 (2013.01); C08F 2/18 (2013.01); C08L 23/0815 (2013.01); C08L 2207/062 (2013.01); C08L 2207/066 (2013.01); C08L 2314/02 (2013.01)] 7 Claims
 
1. A multimodal polyethylene composition obtained by a process for producing the multimodal polyethylene composition in a reactor system,
the reactor system comprising:
(a) a first reactor;
(b) a hydrogen removal unit arranged between the first reactor and a second reactor comprising at least one vessel connected to depressurization equipment allowing adjustment of an operating pressure to a range of 100-200 kPa (abs);
(c) the second reactor; and
(d) a third reactor;
the process comprising:
(i) polymerizing ethylene in an inert hydrocarbon medium in the first reactor in the presence of a catalyst system, comprising 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;
(ii) removing in the hydrogen removal unit 98.0 to 99.1% by weight of the hydrogen in a slurry mixture obtained from the first reactor at a pressure in the range of 103-145 kPa (abs) and transferring an obtained residual mixture to the second reactor;
(iii) polymerizing ethylene and optionally C4 to C12 α-olefin comonomer in the second reactor in the presence of a catalyst system, comprising Ziegler-Natta catalyst or metallocene, and in the pressure of hydrogen in an amount obtained in step (ii) to obtain a first high molecular weight polyethylene or a first ultra high molecular weight polyethylene homopolymer or a copolymer and transferring a resultant mixture to the third reactor; and
(iv) polymerizing ethylene, and optionally α-olefin comonomer in the third reactor in the presence of a catalyst system, comprising 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 with respect to gas in a vapor phase in the third reactor, or optionally the hydrogen is substantially absent, to obtain a second high molecular weight polyethylene or a second ultra high molecular weight polyethylene homopolymer or copolymer,
the multimodal polyethylene composition comprising:
(A) 30 to 65 parts by weight of the low molecular weight polyethylene or the medium molecular weight polyethylene;
(B) 5 to 40 parts by weight of the first high molecular weight polyethylene or the first ultra high molecular weight polyethylene; and
(C) 10 to 60 parts by weight of the second high molecular weight polyethylene or the second ultra high molecular weight polyethylene copolymer,
wherein (A), (B), and (C) each have a different weight average molecular weight.