초록
Drum-type washing machines are gaining in popularity because they have the advantages of a higher washing performance and water conservation. On the other hand, drum-type machines, which have a lower wash liquor-to-fabric ratio, call into question rinsing efficiency. Though rinsing performance is one of the most important factors in effective washing, a criterion method for measuring the rinsing performance has not yet been established. We have used existing methods to evaluate the rinsing performances. In addition, we suggest a method of measuring the electrical conductivity of detergent solutions and verify the relationships with the existing methods. The load was washed once and rinsed from 0 to 5 times. After rinsing, the load was moved to the higher spin extractor, and the extracted solution was measured for alkalinity (IEC 60456), PBIS concentration (AS/NZS 2040.1), LAS concentration, pH and the electrical conductivity of the NaCl solution (KS C 9608) to evaluate the rinsing efficiency. Moreover, LAS in the fabric after the rinsing process was extracted with water by soxhlet and measured. After each step in the laundering process, the load was spun at 600 rpm, 800 rpm or 1000 rpm. Except for the pH method, every other method, which was expressed per unit fabric weight, almost showed the same tendencies as the number of rinses increased. Though, the method of measuring the electrical conductivity of the detergent solutions especially showed the highest correlation with other methods, that method is labor efficient. Therefore measuring the electrical conductivity of detergent solution in this fashion was an efficient way to evaluate rinsing performance.
