REFRIGERATOR OIL COMPOSITION

PURPOSE: To obtain the title compsn. which has excellent valve sludge preventive properties, wear resistance, low-temp. solubility, stability in a cooling medium and antiseize characteristics, by blending particular paraffinic and naphthenic base oils with each other. CONSTITUTION: A distillate of a b.p. of 250W450°C obtd. by distilling a paraffinic crude oil is, e.g., hydrogenated and, if necessary, purified by alkali distillation or sulfuric acid washing. Then, the resultant oil is dewaxed with a solvent and, if necessary, hydrogenated, followed by deep dewaxing treatment etc. Thus, a paraffinic base oil (A) having a pour point ≤-350°C, a sulfur content ≤50ppm and a dynamic viscosity of 5W500cSt (40°C) is obtnd. Subsequently, 2W30wt% naphthenic base oil (B) having a pour point ≤-35°C, a sulfur content of 0.05W1wt% and a dynamic viscosity of 5W500cSt (40°C) obtd. by solvent extraction followed by hydrogenating treatment, clay treatment, etc., is blended with 70W98wt% component A and, if ...