Process for preparing thermosetting urea-formaldehyde resins doped melamine, and use of these resins as impregnating resins.

摘要

METHOD OF MANUFACTURE OF A UREA-FORMALDEHYDE RESIN doped MELANINA, wherein MELANINA TO UREA-FORMALDEHYDE MIXTURE RATIO ADDING F / NH SUB {2} than 1.5, in an aqueous medium at pH Between 6 and 8 and a temperature between 20 and 90 (degrees) C, the amount of melanin such that its proportion in the final resin is between 1 and 5% by weight and then maintained the reaction A A temperature of 80 to 103 (degrees) C, at pH 6.5 to 7.8 for 5 to 15 minutes followed by pH 4.5 5.5 TO OBTAIN A rESIN THAT HAVE A DEGREE CONDENSATION SOUGHT.