PROCESS FOR PRODUCING WATER-REDUCING AND SLUMP-RETAINING TYPE POLYCARBOXYLIC ACID

摘要

A process for producing a water-reducing and slump-retaining type polycarboxylic acid. The process comprises the following steps: S1: providing water and a polyether; S2: providing raw materials including three mixtures A, B and C, liquid caustic soda and a catalyst; S3: starting a stirring paddle, and controlling the temperature in a reaction kettle to be between 20ºC and 30ºC throughout the whole production process; S4: sequentially adding part of the mixture A and a certain amount of the liquid caustic soda, such that the pH value of the mixed solution is weakly acidic; S5: adding the catalyst, and simultaneously dropwise adding the remaining mixture A, all the mixture C and part of the mixture B; S6: after the mixture A and mixture C are completely dropwise added, dropwise adding the remaining amount of mixture B; and S7: after the mixture B is completely dropwise added, adding the remaining liquid caustic soda for neutralization until a specified pH value is reached. The present production process can improve the conversion rate so as to reduce the production cost.