GB677641A - Improvements in or relating to a process of polymerizing ethylene - Google Patents

Abstract

Solid polymers are prepared by polymerizing ethylene in the gaseous state and under elevated pressure, at a temperature below the softeningpoint of the polymer, in the presence of a catalyst which is mixed homogeneously in the reaction zone with the ethylene, an aqueous solution of a surface-active substance being maintained on the interior surfaces of the reaction vessel to prevent access of polyethylene thereto. Catalysts specified are peroxydicarbonate esters of the general formula <FORM:0677641/IV (a)/1> where R1 and R2 may be the same or different organic radicals such as methyl, ethyl, propyl, butyl, amyl, benzyl, phenyl, tolyl, cyclopentyl, methylcyclopentyl, cyclohexyl, vinyl, allyl, and propenyl radicals; tert.-butyl hydroperoxide; and polymeric peroxy compounds produced by the reaction between sodium peroxide and ethylene glycol bis-(chloroformate). Surface-active substances specified are sodium or potassium oleates or stearates, sodium dodecylbenzenesulphonate and mixtures thereof with sodium sulphate, diisopropyl naphthalene sulphonates, alkyl phenol sulphonates, petroleum sulphonates, alkyl sulphonates, sulphonated fatty esters, sulphonated fatty acid amides, sodium lauryl sulphate, sulphated fatty acids, quaternary ammonium halides, phosphorated alcohols, alkyl phosphoric acid soaps, fatty acid soaps of alkylolamines, sodium metasilicate, trisodium phosphate, and sodium hexametaphosphate. The ethylene is preferably purified before polymerization, suitably by treatment with heated copper, alkali metal, or alkaline earth metal. Polymerization may be carried out either intermittently or continuously, the catalyst being injected into the ethylene stream, or separately into the reaction vessel. The solution of surface active substance may be sprayed on to the walls of the reaction vessel, or the reaction vessel may be rolled to distribute the solution on its walls. The polyethylene is collected as an aqueous suspension, and after separation may be milled to improve its flexibility. Specification 560,497, [Group III], is referred to.