Abstract
Washing efficiency was analyzed by a statistical method similar to a method used in a calculation of probability of failure. The method uses statistical distribution of adhesive force of soil and statistical distribution of detergent power. An amount of soil removed was calculated from two distributions. A colored oily soil was spotted on a cotton cloth, and the soiled cloth was washed by a Terg-O-Tometer with alcohol ethoxylate (AE) aqueous solution. Identical soiled cloth was washed four-times using a fresh solution per wash. K/S value of test cloth was measured by digital image-processing system, and removal efficiency was calculated from the K/S value. Temporal changes of removal efficiencies were analyzed by computer simulation, and optimum parameters expressing detergent power were sought. A minimum value of difference between predicted value and experimental value was obtained in each washing condition. Detergent power calculated from parameters increased along with washing temperature and AE concentration. In two-time repetitive washing test by two distinct washing conditions, experimental removal efficiency of second-time washing test was predicted by computer simulation. The results showed that removal efficiency could be analyzed theoretically by the method using two statistical distributions.
