| 摘要 |
PURPOSE:To prepare an epoxy resin compsn. which, when applied to the surface of an electric or electronic part as an insulation coating, forms a coating film capable of being clearly printed by laser irradiation without adversely affecting the electrical and other properties by compounding an epoxy resin compsn. with bismuth oxalate. CONSTITUTION:An epoxy resin compsn. comprising an epoxy resin, a hardener, a filler, etc., is compounded with bismuth oxalate pref. having a mean particle diameter of 100mum or lower pref. in an amt. of 0.5-20wt.% based on the compsn. Bismuth oxalate, a white powder, undergoes decarboxylation when heated to 250-350 deg.C into bismuth oxide (III), a black powder. Hence when the epoxy resin compsn. contg. bismuth oxalate is irradiated with laser beams in accordance with a character or pattern, only an irradiated part of the surface of the compsn. turns black, leaving an unirradiated part white and thus a clear black printing of the character or pattern on a white substrate is made possible. |
