Abstract: An epoxy resin composition comprising a novolak type epoxy resin which is produced from a substituted-phenol novolak and epihalohydrin, and is 0.15 or less in a maximum absorbance of a 3% (W/V) dichloromethane solution of the epoxy resin, the absorbance being measured at a wave number of between 3570 and 3600 cm.sup.-1 with an infrared spectrophotometer having a cell of 2 mm length, which is useful particularly in encapsulating and laminating applications in electronic fields.

Abstract: Unsaturated epoxy esters with improved curability are prepared by the reaction of (1) a partial esterification compound obtained from trimellitic anhydride and/or pyromellitic anhydride and an unsaturated monoalcohol; (2) (i) a partial esterification compound obtained from a dicarboxylic anhydride and an unsaturated monoalcohol and/or ( ii) a polymerizable unsaturated monobasic acid; and (3) a compound containing at least two epoxy groups in one molecule; if desired in the presence of (4) a dicarboxylic acid or a saturated or unsaturated alkyd having carboxyl groups at both terminals and/or a saturated or unsaturated monoglycidyl compound.