PRODUCTION OF OIL-IN-WATER TYPE EMULSION

PURPOSE:To provide an oil-in-water type emulsion having a specific property by allowing a carboxylic acid type anionic high polymer made of a specific polyacrylic acid or a specific carboxymethyl cellulose to exist in the water phase. CONSTITUTION:The oil-in-water type emulsion is obtained by forming a liquid crystal phase of a cationic surfactant by mixing the oil phase containing a di- or tri-long chain alkyl type sparingly water-soluble quaternary ammonium salt cationic surfactant with a part of the water phase and next, mixing the residual water phase to phase-invert the liquid crystal phase. In this case, the carboxylic acid type anionic high polymer made of the polyacrylic acid having carboxyl group >=30% in degree of neutralization or the carboxymethyl cellulose >=0.8 in degree of etherification is allowed to exist in the water phase. As a result, the oil-in-water type emulsion free from gelation due to the increase of viscosity even in the case of incorporating the cationic surfactant with high concn. and capable of keeping low viscosity state having excellent flowability for a long term is easily and economically produced.