GB883748A - Improvements in or relating to glycidyl polyethers - Google Patents

Abstract

Curable compositions comprise (i) a glycidyl polyether having a 1,2-epoxy equivalency greater than 1 and derived from an epihalohydrin and a polyhydric alcohol or phenol, and (ii) 4-40% by weight of (i) of at least one diethanolamine boronate ester of the formula:- <FORM:0883748/IV (a)/1> where R is alkyl of C1-4, phenyl, halogenated phenyl, methyl-phenyl, benzyl, cyclopentyl or cyclo hexyl and R1 is H or any of the above substituents (for preparation see Group IV(b)). The glycidyl polyethers may be prepared from (a) epichlorhydrin or epibromhydrin and (b) 4,41-dihydroxy diphenyl-dimethyl methane, -methyl methane, -mathane or -sulphone, glycerol, propylene glycol, or 1,5-pentanediol in the presence of NaOH or of a mixture of LiOH and KOH. Accelerators which may be present are Cr or Ni acetylacetonate, Co or Cu salicylaldehyde, and methyl or ethyl bromide or iodide. Other optional additives include glass fibres, wood flour, asbestos, silica, hydrated alumina, TiO2, mica, graphite, Ca silicate, poly(glycol maleates) and phenolic or alkyd resins. Uses: Electrical insulation: adhesives.ALSO:Diethanolamine boronates of the formula <FORM:0883748/IV (b)/1> where R is alkyl of C1-4, phenyl, halogenated phenyl, methylphenyl, benzyl, cyclopentyl or cyclohexyl and R1 is H or any of the above substituents, are prepared by refluxing a boronic acid and a diethanolamine in the presence of at least 5% by weight of the reactants of an azeotropizer (e.g. benzene, toluene and xylene) until 2 mols of H2O are removed. The azeotropizer is then removed by heating under reduced pressure, and the product, if solid, may be recrystallized e.g. from acetone. In examples: R is phenyl and R1 is (1) methyl, (2) ethyl and (3) phenyl; in (4) R is n-butyl and R1 is methyl. The compounds are used as curing agents for epoxy resins (see Group IV(a)).