Per-borates in bleaching

The purpose of bleaching agents is to bleach the natural substances in cotton fibres and cellulose fibres that make the fabric yellowish and to bleach spots that are not removed by the laundering process.Borates enhance stain removal and bleaching, stabilize enzymes, provide alkaline buffering, soften water and boost surfactant performance in detergents and cleaners. Their biostatic properties control bacteria and fungi in personal care products. New trials demonstrate that adding borates to laundry soap bars significantly improves their cleaning action and reduce levels of dirt redeposition.Bleaching agents also bleach textile colours and hence should be avoided for coloured textiles. Bleaching also impacts on the fibre structure and in that way reduces the lifetimes of textiles. Hence textile service companies naturally will be very concerned to not over-use bleaching.Per-borates are widely used for bleaching purposes. Bleaching takes place through the use of active oxygen and per-borates are normally only active at temperatures above 60C. To make per-borates active at lower temperatures, it may be necessary to add an ‘activator’ like TAED which reduces the point of activity to around 40C and a stabiliser is also normally added. An example of a stabiliser could be phosphonates in very small amounts.The per-borates are skin irritatants in their pure form. Borates are created during the laundering process. Borates will remain stable in the wastewater treatment plants and may to some extent pass through the treatment plants. Borates have limited acute toxic effects.