GB826262A - Improvements in the stabilisation of polymers - Google Patents

Abstract

Dianils, which may be used to stabilize hydrocarbon polymers, have the formula <FORM:0826262/IV (b)/1> in which R1 and R2 represent hydrogen, alky radicals or aryl radicals, or together with the two bridging C atoms form a carbocyclic group, the total number of carbon atoms in the two radicals being not more than 12, and R3, R4, R5 and R6 represent hydrogen or alkyl radicals with a maximum of 12 carbon atoms, the total number of carbon atoms present in the radicals R1-R6 being between 2 and 32. These dianils which may or may not be symmetrical may be made by condensing 1,2-dioxo compounds with ortho-aminophenols. As 1,2-dioxo compounds there may be used glyoxal, methyl glyoxal, hexane-diones, diacetyl, benzil and cyclic diketones based on cyclohexane-dione and cyclopentane-dione. As ortho-aminophenols there may be used ortho-aminophenol itself or the latter substituted by 1 or 2 alkyl radicals, for example t-butyl or hexyl radicals.ALSO:Polymers of polymerizable hydrocarbons are stabilized by incorporating a dianil of the formula <FORM:0826262/IV (a)/1> in which R1 and R2 represent hydrogen, alkyl radicals or aryl radicals the total number of carbon atoms in the two radicals being not more than 12 and R3, R4, R5 and R6 represent hydrogen or alkyl radicals with a maximum of 12 carbon atoms, the total number of carbon atoms present in the radicals R1-R6 being between 2 and 32. The polymers may be the polymers or copolymers of ethylene, isobutylene, styrene, butadiene, isoprene, e.g. low- and high-pressure polyethylenes and butadiene-styrene copolymer. The anils which may or may not be symmetrical are preferably used in amounts of 0.001 to 1.0% of the polymer and may be obtained by condensation of 1,2-dioxo compounds with ortho-aminophenols. The 1,2-dioxo compound may be glyoxal, methyglyoxal, hexanedione, diacetyl, benzil or cyclic diketones based on cyclohexane-dione and cyclopentanedione.