Process for the manufacture of cast resins of urea-formaldehyde and the like, and resins so produced

Claim 1

A PROCESS FOR THE MANUFACTURE OF A CASTING RESIN, COMPRISING THE STEPS OF HEATING THE REACTION PRODUCT UREA AND A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF FORMALDEHYDE, A MIXTURE OF FORMALDEHYDE AND ACETALDEHYDE, A MIXTURE OF FORMALDEHYDE WITH NO MORE THAN 50% ACRYLALDEHYDE AND A MIXTURE OF FORMALDEHYDE WITH NO MORE THAN 25% GLYOXAL, THE ACRYLALDEHYDE AND GLYOXAL BEING CALCULATED ON THE AMOUNT OF MOLS OF FORMALDEHYDE, 2-2.4 MOLS OF SAID SUBSTANCE BEING USED PER MOL OF UREA, PRE-CONDENSING THE REACTION PRODUCT BY HEATING IT AT BOILING TEMPERATURES FOR 1-9 HOURS AT A PH ABOVE 6.1 AND BELOW 6.85, TAKING REGULARLY SAMPLES FROM THE PRODUCT AND PERMITTING EACH SAMPLE TO COOL TO 18* C. TO MEASURE SAID PH, MAINTAINING SAID PH DURING PRECONDENSATION BY ADDING TO THE REACTION PRODUCT A FINELY PULVERIZED CATALYST SELECTED FROM THE GROUP CONSISTING OF PB,COO, CD,CDO,ZN,ZNO, AND MN2O3 WITH TRACES OF IRON SALTS, THE AMOUNT OF ADDED CATALYST BEING 0.11 TO 0.85 KG. PER 100 KG. OF PURE AQUEOUS FORMALDEHYDE OF 37% CONCENTRATION, REMOVING THE CATALYST AND THE LARGEST PART OF WATER PRESENT IN THE REACTION PRODUCT TO OBTAIN A VISCOUS PRODUCT, LOWERING THE PH OF THE VISCOUS PRODUCT TO BELOW 5.1, ADDING AN ALCOHOL CONTAINING BETWEEN THREE AND SEVEN CARBON ATOMS TO THE VISCOUS PRODUCT THE AMOUNT OF ALCOHOL BEING BETWEEN 5.0 PARTS AND 37.3 PARTS PER 100 PARTS OF UREA AND COMPLETING THE CONDENSATION IN VACUUM.