Masaru Oya

Analysis of Cleaning Process for Several Kinds of Soil by Probability Density Functional Method

A method of analyzing the detergency of various soils by assuming normal distributions for the soil adhesion and soil removal forces was developed by considering the relationship between the soil type and the distribution profile of the soil removal force. The effect of the agitation speed on the soil removal was also analyzed by this method. Washing test samples were prepared by soiling fabrics with individual soils such as particulate soils, oily dyes, and water-soluble dyes. Washing tests were conducted using a Terg-O-Tometer and four repetitive washing cycles of 5 min each. The transition of the removal efficiencies was recorded in order to calculate the mean value (μrl) and the standard deviation (σrl) of the removal strength distribution. The level of detergency and the temporal alteration in the detergency can be represented by μrl and σrl, respectively. A smaller σrl indicates a smaller increase in the detergency with time, which also indicates the existence of a certain amount of soil with a strong adhesion force. As a general trend, the values of σrl were the greatest for the oily soils, followed by those of the water-soluble soils and particulate soils in succession. The relationship between the soil removal processes and the soil adhesion force was expressed on the basis of the transition of the distribution of residual soil. Evaluation of the effects of the agitation speed on µrl and ơrl showed that σrl was not affected by the agitation speed; the value of µrl for solid soil and oily soil increased with increasing agitation, and the µrl of water-soluble soil was not specifically affected by the agitation speed. It can be assumed that the parameter ơrl is related to the characteristics of the soil and the adhesion condition, and can be applied to estimating the soil removal mechanism.

Relation between mechanism of soil removal from fabrics and a parameter derived from probability density functional method for washing force analysis

The probability density functional method is one of the washing force analysis methods that combines the classical kinetic analysis of detergency method and risk calculation method using probability density function. This paper discusses the relation between soil removal mechanisms and the value of σ rl , which is one of the two parameters used in the probability density functional method. Four repetitive washing tests were conducted using test fabrics soiled with iron(III) oxide, carbon black, four kinds of water-soluble dyes and three kinds of oily dyes, and the removal (%) was analyzed with the probability density functional method. The results show that the range of σ rl varied with removal mechanisms; mechanical removal of particle soil (0.01–0.6), dissolution into water of water-soluble soil (0.3–1.4), solubilization of oily soil into surfactant micelle (1.0–2.0) and emulsification or dispersion of oily soil (≥3.0). This tendency can be used for estimating the removal mechanism of any washing system where the soil type is unknown.

Comparison Test of Oily Soil Removal of Japanese Laundry Detergents Using a Regression Formula to Derive Soil Quantity from K/S Value of Colored Oil

Abstract How to calculate the amount of colored oily soil adhered to fabric by measuring the reflectance was studied. Fatty acid, triacylglycerol and hydrocarbon were selected as typical oily soil and mixed with Sudan IV. Removal of fatty acid was greatly affected by alkaline property of washing liquid, and those of triacylglycerol and hydrocarbon were largely affected by interfacial activity of washing liquid. The detergency of Japanese artificial soiled fabric was largely affected by the fatty acid composition.