FIELD: chemistry.
SUBSTANCE: disclosed is an improved solid Ziegler-Natta type catalyst for (co)polymerisation of ethylene and alpha-olefins with high efficiency. Disclosed also are a catalyst system and a method for (co)polymerisation of alpha-olefins. Said catalyst containing titanium, magnesium, aluminium, chlorine and possibly at least one metal M selected from hafnium and zirconium is obtained using a novel method involving the following successive steps: (i) obtaining a first mixture by mixing and heating to temperature of 40 to 200 °C for at least one minute in a liquid hydrocarbon medium of at least one magnesium chloride, at least one titanium compound, at least one carboxylic acid R-COOH, where R is an organic group having from 2 to 30 carbon atoms, and optionally at least one compound of said metal M in such an amount to fall into the following ranges of atomic ratios or molar ratios: M/Ti = 0.0–5.0; Mg/Ti = 3.0–15.0; R-COOH/(Mg + M) = 1.5–8; (ii) adding to first mixture obtained at step (i) at temperature from 10 to 70 °C, a chlorinating agent which is soluble in said liquid hydrocarbon medium in an amount sufficient to cause precipitation of at least 70 % of magnesium and any of said metal M present in solution, in form of solid chlorides, to obtain a second mixture containing a liquid phase and a solid phase, wherein said chlorinating agent is selected from soluble complexes of aluminium trichloride, having one of following general formulas (II) or (III): AlCl3 ∙ OR''R''' (II) AlCl3∙ Ar ∙ HX (III), in which: each R'' and R''' independently represents an organic group selected from a hydrocarbon or halogenated hydrocarbon group having from 1 to 30 carbon atoms, Ar is an optionally substituted aromatic hydrocarbon compound having from 6 to 20 carbon atoms, X is a halogen atom; (iii) adding to a second mixture obtained at a previous step (ii) an organometallic compound of a metal M', having following formula (IV): M'R''''nCl(pn) (IV), in which: M' is trivalent aluminium; R'''' is a linear or branched alkyl radical containing 1 to 20 carbon atoms, "n" is a decimal number having value from 0.5 to p, where p is the valency of M'; and performing the reaction until at least 70 % of the titanium present falls out in the form of a solid compound to obtain said solid catalyst.
EFFECT: technical result is catalyst demonstrates improvement in properties and yield of polymer, particularly high Mw of obtained polymers and copolymers of ethylene.
19 cl, 5 tbl, 36 ex
