TW231295B - Method for producing polyethylene - Google Patents

Abstract

A continuously polymerizing method for ethylene or ethylene and alpha-olefin by using high-yield Ziegler-Natta catalysts, which ischaracterized in: the catalysts (Z) are made of compounds such ashydrogenated polysiloxane, organomagnesium, organic diacids, organicphthalates, alcohols, organic alumino-halides, halides of transitionalmetal; an organometallic halide (B) is introduced during the first stagepolymerization, an organometallic compound (A) is introduced to the formedpolyethylene and solvent, catalysts, un-reacted monomer to undergo thesecond stage polymerization reaction; in which the organometallic compound (A) is selected from an organic aluminum compound having the general formula: Al(R1)3, in which R1 is selected from a monovalent organic group with 1~8 carbons,such as methyl, ethyl, n-butyl, isobutyl; in which the organometallic halide (B) is selected from an organicalumino-halide having the general formula: AlR2mX3-m, in which R2 is selected from a monovalent organic group with 1~8 carbons,such as methyl, ethyl, n-butyl, isobutyl; X is a halogen atom, such aschlorine, bromine, 1<=m<=2;in which the organic diacid is selected from a compound having the generalformula: R5(COOH)2 or an organic anhydride with the general formula: R6(CO)2O, R5 and R6 can separately be H2 or a divalent organic group with 1~10carbons, such as -CH2-, -C2H4-, -C4H9-, -C6H4-; in which the organic phthalate is selected from a compound having thegeneral formula: R7(COOR8)2, R7 is H2 or a divalent group with 1~20 carbons, such as -CH2-, -C2H4-,-C4H9-, -C6H4-; R8 is a monovalent group with 1~12 carbons, such as methyl,ethyl, n-butyl, isobutyl; in which the alpha-olefin used in the copolymerization reaction has ageneral formula: CH2=CHR12, R12 is a linear or branched alkyl with 1~6 carbons, such as methyl, ethyl,n-butyl; in which the first stage reaction is carried out at 60~90 deg.C, 1 atm to20 kg/cm2, hydrogen is 10~70% of the whole pressure, 1~10 mg of catalysts(Z) per liter of solvent, 0.3~10 mmole of organometallic halide (B) perliter of solution, the yield is 30~70%; in which the second stage reaction is carried out at 60~90 deg.C, 1 atmto 20 kg/cm2, hydrogen is 20~80% of the whole pressure, 0.05~5 mmole oforganometallic compound (A) per liter of solution, the yield is 70~30%; in which during the reaction, the overall ratio of the transitional metalcontained in the solid catalyst (Z) to the organic aluminum compound,(A)+(B), is 1:1~1200 a.m.u.; in which in the first stage reaction, the ratio of the transitional metalto the organometallic halide (B) is 1:1~800; in which the alpha-olefin used in the copolymerization is propylene,1-butene, 1-hexene and the amount added is 1~10 % of the total amount.