FIELD: polymer production. SUBSTANCE: gas-phase high-density polyethylene production process involves contact of mixture containing ethylene and one or several alpha-olefins with supported product of reaction between bis-hydrocarbylsilyl chromate and hydrocarbylaluminum or hydrocarbylboron compound in fluidized-bed reactor provided with gas recirculation line under following polymerization conditions: (i) aluminum-to-chlorine atomic ratio is limited by ca. 0.1:1 and ca. 2.9:1; (ii) amount of catalyst lies within a range of ca. 0.005 to ca.0.25 weight parts per 100 weight parts of high-density polyethylene; (ii) partial pressure of ethylene lies within a range of ca. 14.06 to ca. 28.12 kg/sq.cm; (iv) oxygen or another catalytic poison is introduced into reactor in amounts from ca. 0.005 to ca. 0.5 volume parts per 1 million of volume parts of ethylene; (v) alpha-olefin-to-ethylene volume ratio ranges from 0.0001:1 to 0.1:1; (vi) hydrogen is introduced into reactor in amounts from ca. 0.005 to ca. 0.5 mole per 1 mole of volume parts of ethylene; (vii) polymerization is carried out at temperature from ca. 80 to ca. 110 C; (viii) relatively low boiling inert hydrocarbon is introduced into gas recirculation line in amounts large enough to raise dew point of recirculation gas, which consists of alpha-olefins and other reactor gases, and recirculation gas is partially condensed and recycled into reactor where it promotes cooling by way of evaporation. EFFECT: increased resistance to slow growth of cracks during pipe-making operation and increased workability of molded products. 7 cl, 1 tbl, 5 ex
