UV-resistant epoxy-chalcone resins

4,4'-Dihydroxychalcone (chalcone A) or 3-ethoxy-4,4'-dihydroxychalcone (chalcone B - a new compound) were obtained and then reacted with bisphenol A and epichlorohydrin (eqns. 1 and 2 and Tables 3 and 4). The concentration of chalcone in the bisphenol mixture should range from 40 to 60 mol% to yield a resin with good properties. Photo-crosslinking was carried out with a UV lamp at 150 W. The structure of the resulting resins before and after crosslinking was examined by FT-IR, NMR and UV techniques. The breaking strength (Figs. 1 and 3) of the resins was studied in relation to resin composition and irradiation time. The good solubility of the chalcone B-based resins and their nontoxicity makes the resin 16 (Table 4) to be the best choice for printed circuit applications (Fig. 8).