Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With oxygen or halogen containing chemical bleach or oxidant...
Patent
1996-01-26
1998-01-13
Einsmann, Margaret
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With oxygen or halogen containing chemical bleach or oxidant...
25218625, 25218626, 2521881, 427213, C11D 1700
Patent
active
057079536
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a coated bleach composition containing amidoperoxyacid which composition has been spray coated in a fluidized bed with a coating of a water-soluble salt. The present invention also relates to a coating process for application of the coating to the bleach composition.
Amidoperoxyacid bleach granules are known from U.S. Pat. No. 5,055,218. These granules generally contain 5-70 weight percent of amidoperoxyacid, 1-40 weight percent of a surfactant and 10-95 weight percent of a hydratable material. These granules are said to have a good dissolution rate in wash liquor, a good solution stability and are compatible with dry, granular detergents to make a bleach detergent composition. This patent publication does not mention caking of the granules.
The present inventors have found that the granules of U.S. Pat. No. 5,055,218 suffer from a significant caking problem, i.e. the granules tend to stick together upon storage or application of pressure as in, for example, large transportation containers. Accordingly, there is a need for a solution to this caking problem in order to facilitate the storage and transport of such amidoperoxyacid bleach granules.
Caking has been recognized as a problem for granular detergents in U.S. Pat. No. 3,950,275, for example, where it is proposed to coat the detergent granules with a builder such as anhydrous sodium sulfate, sodium tripolyphosphate, and sodium carbonate among others. The coating is performed by a known method such as using a drum granulator (example 1). The examples demonstrate a reduction in caking for these detergent granules when coated. No mention is made of the coating of peroxy-containing bleach granules in this publication.
Another patent relating to the caking of detergent granules is U.S. Pat. No. 3,989,635 which proposes to spray a coating agent selected from aqueous solutions of alkali metal silicates, carbonates and hydroxides either alone or in combination with a powder of alkali metal silicates, sulfates, carbonates and hydroxides. The coating may be accomplished in a revolving drum, a revolving cross drum or a fluidized tower, all of which methods are deemed equivalent. Again, it is not suggested to coat peroxy-containing bleach granules.
In addition, U.S. Pat. No. 4,997,590 discloses the spray coating of extruded bleach activator compositions with an aqueous solution of a water-soluble dye and a water-soluble hydratable material such as sodium sulfate. This spray coating is carried out in a drum granulator with the objective of colouring the bleach activator compositions. The use of Na.sub.2 SO.sub.4 reduces agglomeration of the particles and promotes even colouring. Although the coating process of this patent reduces cake strength for the first 30 minutes after the coating, after 24 hours uncoated particles exhibit a better cake strength than coated particles. Accordingly, this process is not suited to prevent caking during storage and transport of the particles.
British patent specification 1,476,682 and U.S. Pat. No. 3,494,787 both propose the coating of aliphatic, alicyclic and aromatic peroxyacids to reduce or prevent decomposition of the peroxyacid and to provide exotherm control should decomposition occur. The preferred peroxyacid is perphthalic acid. Among the coating agents employed are the alkali metal sulfates and alkaline earth metal sulfates. The coatings are applied by forming a fluidized bed of the sulfate coating material and feeding preformed peroxyacid particles to the fluidized bed. These publications do not mention caking.
However, British patent application 2,032,421 notes that coatings formed by the process disclosed in the above two patent specifications are not continuous, are very expensive and that the coated compositions tended to cake. Accordingly, this publication leads one of skill in the art away from the process suggested by the above two patent specifications when faced with a caking problem. Instead of the fluidized bed process, GB 2,032,421 advocates simply mixing dry or moist peroxyac
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Bouwmeester Johannes Gerhardus Bernardus
Kooijman Cornelis
Manuhutu Charles Frederik Hansfort
Ploumen Jan Joseph Hubert
Van't Land Cornelis Marinus
Akzo Nobel N.V.
Einsmann Margaret
Mancini Ralph J.
Morris Louis A.
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