Compositions – Electrolytes for electrical devices
Patent
1993-07-30
1995-05-02
Stoll, Robert L.
Compositions
Electrolytes for electrical devices
25218625, 25218627, 25218631, 25218638, 252 99, 252102, C11D 3395, C11D 754, C01B 1504, C09K 300
Patent
active
054116732
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/US92/00664 filed Jan. 28, 1992.
This invention relates to solid peroxy acid bleach precursor compositions and especially to particulate detergent compositions incorporating inorganic perhydrate bleaches together with N- or O-acyl group--containing peroxycarboxylic acid bleach precursors (so-called bleach activators). Such compositions have come into widespread use in recent years as heavy duty fabric cleaning products, particularly in automatic washing machines. The growth in usage of bleach activators has mirrored a decrease in fabric wash temperatures which itself has accompanied an increase in the proportion of fabrics that are colored.
One problem that has become more significant as a result of these trends is that of damage to fabric colors and materials caused by the development of localised high concentrations of bleaching species. High bleach concentrations can arise around any particulate bleaching species for several reasons. The bleaching species may itself have an intrinsically low solubility, its solubility may have been hindered by the presence of other materials such as viscous surfactant phases or the agitation regime in the immediate environment of the bleach species may not be high enough to disperse the dissolved bleach. Where a bleach activator forms a component of the composition the potential problem is increased. In addition to the potential for localised high concentrations of perhydroxyl ion arising from dissolution of the inorganic perhydrate normally contained in laundry detergent compositions, the perhydrolysis of the bleach activator to form peroxycarboxyl anions can give rise to significant localised peroxycarboxylate bleach concentrations.
The development of so-called concentrated products and their delivery via dispensing devices placed in the machine drum together with the fabric load has merely served to exacerbate these problems. Accordingly a need exists to provide detergent compositions in which the bleach activator is incorporated in a form that minimises and preferably eliminates damage to fabric colors and materials during its dissolution and perhydrolysis in the wash liquor.
The prior art contains numerous examples of bleach activators coated or agglomerated so as to increase their stability on storage in detergent compositions and/or to influence their solution behaviour.
EP-A-0070474 discloses granulate bleach activators prepared by spray drying an aqueous pumpable dispersion containing an N-acyl or O-acyl compound together with at least one water soluble cellulose ether, starch or starch derivative in a weight ratio of activator to coating of from 98:2 to 90:10.
GB-A-1507312 discloses the coating of bleach activators with a mixture of alkali metal C.sub.8 -C.sub.22 fatty acid salts in admixture with the corresponding fatty acids. GB-A-1381121 employs a molten coating of inter alia C.sub.14 -C.sub.18 fatty acid mixtures to protect solid bleach activators. GB-A-1441416 discloses a similar process employing a mixture of C.sub.12 -C.sub.14 fatty acids and C.sub.10 -C.sub.20 aliphatic alcohols. EP-A-0375241 describes stabilised bleach activator extrudates in which C.sub.5 -C.sub.18 alkyl peroxy carboxylic acid precursors are mixed with a binder selected from anionic and nonionic surfactants, film forming polymers fatty acids or mixtures of such binders.
EP-A-0356700 discloses compositions comprising a bleach activator, a water soluble film forming polymer and 2-15 % of a C.sub.3 -C.sub.6 polyvalent carboxylic acid or hydroxycarboxylic acid for enhanced stability and ease of dispersion/solubility. The carboxylic acid, of which a preferred example is citric acid, is dry mixed with the bleach activator and then granulated with the film forming polymer. The citric acid is asserted to provide an enhanced rate of dissolution of the bleach activator granules.
EP-A-0382464 concerns a process for coating or encapsulation of solid particles including bleaching compounds and bleach activators in which a melt is formed of coating material in which
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Agar Joseph T. H.
Fraser Douglas G.
Anthony Joseph D.
Borrego F. A.
Rasser J. C.
Reed T. D.
Stoll Robert L.
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