Liquid cleaning compositions and their use

#The present invention relates to liquid cleaning compositions containing proteolytic enzymes and stabilising systems for those enzymes. It also relates to methods of using such compositions for the cleaning of substrates.

#In liquid detergent compositions, especially those for the washing of textile fabrics, it is common to include one or more enzymes for assisting removal of various kinds of soil. Amongst these are proteolytic enzymes, often referred to as “proteases”. Proteases are used to assist in removal of protein-based soil. However, the very nature and activity of these enzymes means that they attack any other component in the liquid composition which has a protein-like structure. As a result, they can degrade other enzymes in the liquid,.as.well as undergoing self-degradation. To counteract this, it is usual also to incorporate an enzyme stabilising system. Such stabiliser systems commonly consist of a boron compound, eg. borax, together with a polyol, eg. glycerol or sorbitol. These components are believed to form an enzyme-inhibiting complex by dilution of the composition into the wash liquor, disabling the inhibiting effect so that the protease can act upon the proteinaceous soil.

#Other protease stabilisers such as calcium chloride/calcium formate are also known but are not as effective as those systems based on boron. However, for environmental reasons, it is desired to reduce the amount of boron in the composition.

#The following example formulation was prepared:

#2 Parts by Ingredient Weight LAS-acid 7.02 sLES 13.13 Coconut fatty acid 1.00 NI 7EO 8.25 NaOH 0.63 Monoethanolamine 0.25 Sodium Citrate 2aq 4.00 Sodium tetraborate. 3.81 5aq Sorbitol 4.06 PPG 4.42 Fluorescer 0.26 Protease Enzyme 0.4 (4%) Minors 0.63 Water Balance PPG = propylene glycol LAS acid = C10-C14 alkyl benzene sulphonic acid sLES = sodium lauryl ether sulphate (average 3 ethyleneoxy units) NI xEO = C12-C13 fatty alcohol ethoxylated with an average of x ethyleneoxy units.

#Polyoxometalate (Me3NH)4(NbO2)PW11O39 disclosed in Racherla et al, EP-A-1 141 210 was dosed at 0.5% by weight on top of the control composition above.