BIMODAL POLYETHYLENE COPOLYMER COMPOSITION AND PIPE MADE FROM SAID COMPOSITION Russian patent published in 2024 - IPC C08L23/08 C08F10/02 C08F210/16 C08F4/6592 F16L9/00 B29C48/18 

FIELD: chemistry.

SUBSTANCE: group of inventions relates to a bimodal composition of an ethylene/1-hexene copolymer for making pipes, a method for synthesis of a bimodal composition of an ethylene/1-hexene copolymer, a pipe consisting of a bimodal composition of an ethylene/1-hexene copolymer and a method of making a pipe. Bimodal composition of an ethylene/1-hexene copolymer for making pipes consists of an ethylene/1-hexene copolymer component with a higher molecular weight (HMW component), having a molecular weight distribution from 4.05 to 4.34, a homopolymer of polyethylene with a lower molecular weight or a component of an ethylene/1-hexene copolymer with a lower molecular weight (LMW component) having a molecular weight distribution of 2.84 to 2.88; where the fractionation of the components, characterized by the weight fraction of the PMM component and the weight fraction of the LMW component, ranges from 36.9 to 49.1 wt.% and from 63.1 to 50.9 wt.%, respectively, of the total weight of the HMW and LMW components, wherein the bimodal ethylene/1-hexene copolymer composition is obtained using a combination of a bimodal catalyst system and an auxiliary catalyst in the presence of molecular hydrogen gas; wherein said bimodal catalyst system is obtained by bringing the first activator into contact with bis-(2-(pentamethylphenylamido)-ethyl)-aminozirconium dibenzyl and (methylcyclopentadienyl) (1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl, wherein said auxiliary catalyst is obtained by contacting a second activator with (methylcyclopentadienyl) (1,3-dimethyl-4,5,6,7-tetrahydroindenyl)-zirconium dimethyl; wherein the first and second activators are the same or different; and wherein the molar ratio of molecular hydrogen gas to ethylene is from 0.001 to 0.0050; and the molar ratio of 1-hexene to ethylene is from 0.00450 to 0.01000, and has density from 0.9486 to 0.9584 g per cubic centimetre (g/cm³), measured in accordance with ASTM D792-13, method B and molecular weight dispersion from 15.3 to 22.4, measured by a test method using gel permeation chromatography (GPC). Method of making the pipe includes a step for extruding the melt through an annular die, configured to form a cylinder to obtain an initial cylinder with solid walls from a bimodal composition of an ethylene/1-hexene copolymer or a step of extrusion and spiral winding of the melt around the mandrel configured to form a wall with a soldered seam, to obtain a wall with a soldered seam and soldering unsoldered seam of wall with unsoldered seam to obtain initial cylinder with walls with sealed seam.

EFFECT: providing pipes from a bimodal composition of an ethylene/1-hexene copolymer, characterized by an increased strain hardening modulus and characteristics of an accelerated creep test with a full notch.

10 cl, 4 tbl, 3 ex