Urea-formaldehyde compositions and their manufacture

Claim 1

A PROCESS FOR PRODUCING A STABLE LIQUID UREA-FORMALDEHYDE CONDENSATE CONDENSATE CONTAINING UREA IN A MOLE RATIO TO FORMALDEHYDE GREATER THAN 1, AND CHARACTERIZED BY FILMFORMING PROPERTIES, WHICH COMPRISES ADMIXING UREA WITH AQUEOUS FORMALDEHYDE IN A MODE RATIO OF UREA TO FORMALDEHYDE WITHIN THE RANGE OF FROM 0.3:1 TO 0.6:1 UNDER TEMPERATURE CONDITIONS FOR DISSOLVING THE UREA IN THE SAID AQUEOUS FORMALDEHYDE; MAINTAINING THE RESULTING UREAFORMALDEHYDE SOLUTION, AS A REACTION MIXTURE, AT A TEMPERATURE OF FORM 50 TO 100*C. AND AT A PH OF FROM 7 TO 10 FOR A PERIOD OF FROM 5 TO 60 MINUTES; THEREAFTER REDUCING THE PH OF THE SAID REACTION MIXTURE TO AVALUE WITHIN THE RANGE OF FROM 2.5 TO 5.0 AND MAINTAINING SAME AT A TEMPERATRUE WITHIN THE RANGE OF FROM 40 TO 100*C. FOR A PERIOD OF FROM 10 TO 2 HOURS; ADDING ADDITIONAL UREA TO THE RESULTING REACTION MIXTURE IN AN AMOUNT SUFFICIENT TO PROVIDE A MOLE RATIO OF TOTAL ADDED UREA TO TOTAL ADDED FORMALDEHYDE THEREIN GREATER THAN 1:1 BUT NOT EXCEEDING 2:1 AND THEN HEATING SAME FOR A PERIOD OF FROM 1 TO 30 MINUTES AT A TEMPERATURE WITHIN THE RANGE OF FROM 35 TO 80*C., AND RECOVERING RESULTING LIQUID REACTION MIXTURE AS SAID LIQUID UREA-FORMALDEHYDE CONDENSATE.