金属イオン封鎖剤の洗浄助剤的効果

It has been reported that standard carbonaceous soiled fabrics used for evaluation of detergency gave insensitive or incorrect measure of soil removal if builders such as sodium tripolyphosphate were present in a detergent test solution. On the contrary, condensed phosphate showed pronounced increase on detergency for naturally soiled fabrics. Explanation for the above mentioned fact has been given as follows. There are more or less polyvalent cations, mainly calcium ions, in natural dirts fabrics inevitably. These cations cause particulate soils to aggregate on fabrics, for most particulate soils and cellulose fibres are negatively charged in an aqueous system. (Schulze-Hardy rule about flocculation in colloid chemistry). A condensed phosphate builder acts as sequestering agent to chelate these harmfull flocculating cations in detergent solution. Particulate soils on fabrics will be dispersed by surfactant more easily after calcium ions are removed in solution and then washing will proceed. The authors intended to improve the test fabrics for detergency evaluation to show similar tendency about soil removal as for naturally soiled fabrics whenever a builder is present and also to give an indirect substantiation of the theory. The standard car bonaceous soiled fabrics and test fabrics soiled with ferric oxinate were dipped in aqueous calcium chloride solution in order to contaminate with calcium as naturally soiled cloths do. The soiled fabrics with calcium and those without calcium were washed by surfactant solutions with and without a builder. Two kinds of surfactant and three kinds of sequestering agents were used. Degrees of detergency were obtained in each experiments and were compared with each other by statistical analysis. The builder effect could not be found for carbonaceous soiled fabrics without and even with calcium. On the other hand, the test fabrics soiled with ferric oxinate and calcium showed significantly larger degrees of detergency for surfactant solution with builders than for it without builders. The theory of builder effect by sequestering mechanism holds in the case of soiled fabrics with ferric oxinate without any contradiction. However, behaviors of carbonaceous soiled fabrics for detergency could not be explained by this theory.