Method of preparing aqueous alkaline phenol-aldehyde condensates

Claim 1

A PROCESS FOR PREPARING A PHENOL-FORMALDEHYDE CONDENSATE IN AQUEOUS ALKALINE MEDIUM WHICH COMPRISE (A) CO-REACTING IN AQUEOUS MEDIA 1 MOLAR PROPORTION OF PHENOL WITH FROM 2.2 TO 3.5 MOLAR PROPORTIONS OF FORMALDEHYDE IN THE PRESENCE OF FROM 0.15 TO 0.6 HYDROXYL EQUIVALENT PROPORTIONS OF AN INORGANIC ALKALINE CATALYST AT A TEMPERATURE OF FROM ABOUT 100 TO 165*F. UNTIL A FREE FORMALIDEHYDE LEVEL OF WITHIN 10% OF THE MINIMUM IS ATTAINED, AND (B) CONTINUING THE CO-REACTION OF THE PHENOL AND FORMALDEHYDE AT A TEMPERATURE OF FROM ABOUT 175*F. TO REFLUX TEMPERATURE UNTIL A 70*F. VISOSITY OF AT LEAST 100 CENTIPOISES IS ATTAINED; FROM ZERO TO ABOUT 0.3 MOLAR PROPORTIONS OF PHENOL BEING CHARGED DURING STEP (B) PROVIDED THE RELATIVE PROPORTION OF PHENOL TO FORMALDEHYDE IS MAINTAINED WITHIN THE RANGE SPECIFIED IN STEP (A) AND FROM ZERO TO 0.85 HYDROXYL EQUIVALENT PROPURTIONS OF INORGANIC ALKALINE CATALYST BEING CHARGED DURING THE INTERVAL STARTING WITH THE COMPLETION OF STEP (A) AND ENDING WITH THE COMPLETION OF STEP (B) PROVIDED TO TOTAL INORGANIC ALKALINE CATALYST CHARGED DOES NOT EXCEED ABOUT 1.0 HYDROXYL EQUIVALENT PROPORTION PER MOLAR PROPORTION OF TOTAL PHENOL CHARGED; SAID INORGANIC ALKALINE CATALYST BEING SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL AND ALKALINE EARTH HYDROXIDES, OXIDES AND SALTS OF WEAK ACIDS.