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Low temperature bleach catalysts for improved tea stain removal


*Corresponding author
Clariant Produkte (Deutschland) GmbH, BU Emulsions, Detergents & Intermediates, Industriepark Hoechst, D562, 65926 Frankfurt am Main, Germany


In comparison to hand dishwashing, machine dishwashing is more convenient, and economically and ecologically preferred. Recently published consumer surveys, however, point out that short cleaning cycles at temperatures below 50°C fail to remove stubborn tea stains adequately. To fill the gap, Clariant extended its bleach product range by adding two new bleach catalysts designed for low temperature tea stain removal.
Peractive® MnOx, a synthetic analogue of the mineral Lindbergite, offers a new proposition for a low temperature bleach catalyst in automatic dishwashing detergents. The eco-friendly, biodegradable catalyst enables tea stain removal at temperatures below 50°C. Even more reactive is Peractive® MnTACN, a multi-active bleach catalyst which also supports starch removal and acts as a silver corrosion inhibitor.
Both catalysts are available in the form of storage stable co-granules (Peractive® FDO) combining the cleaning benefits of the new catalysts with the hygiene properties of the standard bleach activator tetraacetyl ethylenediamine (TAED).


Automatic dishwashers became commercially available in Europe at the beginning of the 1960s. Cleaning conditions characterized by high water consumption (75 l per wash), high temperature (75°C) and 40 g chemicals per wash made it work. The detergent based on phosphate, meta-silicate and chlorine-releasing agents resulted in a high alkaline formula (pH 12-13) with excellent cleaning and stain removal properties. These harsh conditions were standards for nearly two decades in which penetration of dishwashers in households continuously grew as more and more people could afford them.
At the end of the 1980’s, toxicological concerns and the development of powerful cleaning enzymes forced a re-formulation of ADW detergents to low-alkaline powders (pH 9 to 11). A new bleach system, a combination of perborate and tetraacetyl ethylenediamine (TAED) was compatible with sensitive enzymes and gave good tea stain removal performance at 65 to 75°C. Later on, more convenient application forms (e.g. tablets) and the substitution of perborates by sodium percarbonate (SPC) not only reduced the amount of chemicals use ...