GB790083A - Improvements in or relating to hardening agents for epoxide resins - Google Patents

Abstract

Epoxide resins having an epoxide equivalent of more than one are hardened by reacting therewith products obtained by reacting an epoxide having an epoxide equivalent of less than one with a polyamine. The hardening agent is preferably obtained by condensing dihydric phenols with epi- or dichlorhydrins in proportion ranging between 1 : 0.5 and 1 : 1 in alkaline medium and without isolating the reaction product adding the polyamine dissolved in butanol or ethylene glycol. The epoxide resins are hardened by the amine adduct by heating the mixture for an hour at 70 DEG C. or for one quarter hour at 150 DEG C. In examples: (1) 228 parts by weight of p,p1-dihydroxydiphenylpropane are dissolved in 720 parts of 5 per cent caustic soda solution and condensed at 40 DEG C. with 83 parts of epichlorhydrin. The resinous epoxide obtained is dissolved in butanol, the butanol solution washed with water and the resin freed from volatiles by distillation. 50 Parts of the condensate are dissolved in ethyleneglycol and the solution heated with 50 parts triethylenetetramine for 1 hour at 100 DEG C.; volatile components including excess amine are removed by distillation in vacuo. The hardening agent thus obtained was used to harden epoxide resins having epoxy numbers of 1.6, 3.8 and 6.1; (2) a similar amine adduct was prepared by heating 114 parts p,p1-dihydroxydiphenylpropane with 41.5 parts epichlorhydrin and reacting the product with 90 parts triethylenetetramine; (3) six butanolic solutions obtained as described in (1) were reacted respectively with 130, 100, 50, 30, and 10 parts of triethylenetetramine and products containing respectively 5.19, 4.84, 3.63, 2.73, 2.2 and 1.3 per cent nitrogen were obtained; the hardening effect of these products was found to decrease with fall of nitrogen content. Specifications 691,543 and 779,566 are referred to.