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LAUNDRY CARE
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Gentler hydrophobics
‘Hydrophobic’ oxygen bleaches (e.g. PBS/NOBS) have the advantage that they have a tendency to migrate to the fabric surface
and work there, rather than exerting their activity within the wash liquor. In certain usage conditions these bleaches have
been found to have an adverse effect on some synthetic fabrics which have unsaturated moieties or a high degree of polymer
cross-linking: perhaps because of a side reaction to the bleaching process involving a single-electron, free radical mechanism.
A ‘polymer-kind’ hydrophobic bleach has been described which does not have this effect: a peroxyacid bleach precursor
combined with an antioxidant and a binder/agglomerating agent. The antioxidant can be a phenolic ester of, for example,
boric acid and the combination appears to ‘scavenge’ free radicals, hence preventing fabric damage.
Corrosion inhibition
Borates are anodic inhibitors: that is, they protect ferrous metals from corrosion. It is thought likely that borate
produces a ferric-borate layer on metal surfaces, encouraging the formation of ferric oxide which acts as a barrier to ion
transport - particularly ferric ions away from the metal surface.
Corrosion of steel components in laundry and dishwash machines, particularly those used in industry, can be a problem and
borates can usefully aid the action of the silicates often employed to mitigate this. In industrial metal cleaning and
degreasing applications, borates can also be used for this reason. Their anti-tarnish property is of relevance in domestic
dishwasher formulations where the protection of the surface of metal utensils is important.
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