ZEOLITES AND NOVEL SILICATES AS RAW-MATER IALS FOR DETERGENTS

Special crystalline and amorphous silicates soda/silicate compounds as well as zeolite P are offered as an alternative to zeolite A. These b uilders have in common that they contribute to the softening of water and thus to the inhibition of coarse precipitations which may lend to incrustations on textiles The mechanisms of these builders are however quite different. Whereas the builder efficacy of zeolites is essentia lly due to the ion exchange capacity, the builder properties of the sp ecial silicates are largely determined by the dissolution kinetics and the structure of the formed silicate anions. Physicochemical investig ations and washing tests show that zeolite P as well as the special si licates may partially or completely substitute zeolite A. A benefit of zeolite P is, that the calcium binding is quicker and substantially s tronger in comparison to zeolite A. As a consequence, the amount of or ganic cobuilders (e.g. polycarboxylates) that have to be used in combi nation with Zeolite A can be reduced in the detergent formulas. Furthe rmore, zeolite P exhibits a superior uptake for non-ionic surfactants in comparison to zeolite A. This is essentially due to the smaller par ticle size of zeolite P and may be of potential advantage for special production technologies. Additionally, zeolite P shows a better compat ibility with bleach components in some detergent formulas. All silicat es are distinguished from the heterogeneous zeolites by several proper ties: they are principally soluble, they contribute to the alkalinity of the washing liquor and they are generally more compatible to sensit ive bleach components like percarbonate. Soda/silicate compounds are e specially suited for the partial substitution of zeolite A. On the oth er hand crystalline layered silicates (like delta-sodium disilicate) a nd especially certain amorphous silicates with reduced solubility may completely substitute zeolite due to their superior antiincrustation e fficiency. A prerequisite for the maintainance of the good builder eff iciency of the silicates is a gentle processing with a far reaching pr eservation of the silicate or granule structure. The possibilities to process zeolites are surely more versatile. The future market developm ent of the silicates as well as of zeolite P depends particularly on t he price development.