The products, which are based on polyepoxide, polymerize on exposure to actinic radiation and are useful in the preparation of printing plates for offset printing and of printed circuits, particularly multilayer circuits. They are formed by coupling two molecules of a polyepoxide by means of a dihydric phenol which contains a chalcone or chalcone-like grouping, such as 1,3-bis(p-hydroxyphenyl)prop-1-en-3-one or 1,5-bis(p-hydroxyphenyl) penta-1,4-dien-3-one, so sensitizing the material to the radiation, and then, to achieve polymerizability, ring-opening at least some of the residual epoxide groups so as to incorporate olefinic acyloxy groups (R.sup.6 CH=C(R.sup.5)COO-), such as sorboyl groups.