抄録
Sodium tripolyphosphate has ranked as the most important builder for laundry detergents since about 1955, however, phosphate-containing synthetic detergents have yet been criticized in recent years due to their contribution to the eutrophication of stagnant waters. For such a reason, the phosphate-containing synthetic detergent-one of the causing material of the eutrophication-have been restricted legislatively.
Many substitutes have been enumerated for detergent builder, Na A type of zeolite has finally been adopted as a phosphate substitute in spite of its water-insoluble pro perty.
A material for detergent builder has to possess hardwater softening property and alkalinity-giving property to washing water. In such a meaning Na A type of zeolite indicates an excellent ion-exchange capacity and hard water softening property among other zeolites. Further, the zeolites for detergent builder has to possess fine crystallinity, specifically, the mean particle size of zeolite should be smaller than one μM and possess excellent dispersibility, since they wash cloths at low temperature in Japan.
Such a small mean particle size of zeolite can be obtained by reacting sodium aluminate with activated silica gel from Japanese acid clay treated with mineral acid. And this process is characterized by producing the small mean particle size of zeolite without agglomeration at low cost.
