Durable primer composition

A primer composition comprising

• (A) 100 parts by weight of a silicone-modified epoxy resin which has both epoxy groups and silicone-bonded alkoxy radicals, said silicone-modified epoxy resins being the condensation reaction product between
• (a) an alkoxy silicon compound being expressed by the average unit formula ##STR6## wherein R represents a monovalent radical selected from the group consisting of hydrocarbon radicals and substituted hydrocarbon radicals having at lease one hydrogen atom substituted by a halogen atom, cyano, mercapto, hydroxyl, methacryloxy, acryloxy, glycidoxy, and 3,4-epoxycyclohexyl, X represents an alkoxy radical or an alkoxyalkoxy radical, a has a value from 0 to 2 inclusive, b has a value from 1 to 4 inclusive and the sum of a+b has a value from 1 to 4 inclusive,
• (b) an epoxy resin having both epoxy groups and hydroxyl radicals in the molecules,
• where (a) and (b) are present in amounts sufficient to satisfy the following relationship ##EQU3## (B) 10 to 100 parts by weight of an aminoxy organosilicon compound having per molecule at least one silicon-bonded aminoxy radical which is expressed by the formula
• R.sub.2.sup.1 NO Si.tbd.
• wherein R' represent hydrogen atom, a monovalent hydrocarbon radical, a halogenated monovalent hydrocarbon radical, or two radials represented by R.sup.1 can be bonded together, and (C) 0.1 to 100 parts by weight of an organotitanate.