Abstract: Bacteriostasis liquid detergent containing sodium fatty alcohol ether carboxylate (AE₉C) and didecylmethylhydroxyethylammonium chloride (DEQ) was designed and formulated.The cold resisting,heat resisting and freeze-thaw stability of the liquid detergent products were tested,and their foaming power,detergency as well as bacteriostasis efficacy was evaluated by Ross-Miles foam meter,Terg-O-Tometer and suspension quantitative method,respectively.The results showed that the liquid detergent product displays excellent stability.Its foaming power and detergency are not affected by water hardness.When the mass ratio of AE₉C to DEQ is 7∶3,foaming power of the product achieves the minimum.When the mass ratio of AE₉C to DEQ is lower than 2∶8,its detergency test result is unqualified.When the mass ratio of AE₉C to DEQ is 7∶3,6∶4 or 5∶5,all the bacteriostasis rate of the three kinds of liquid detergent product against Staphylococcus aureus and Escherichia coli achieves 100%.

Key words: bacteriostasis liquid detergent, sodium fatty alcohol ether carboxylate, didecylmethylhydroxyethylammonium chloride, formulation optimizing