Compositions – Oxidative bleachant – oxidant containing – or generative – Composition containing a stabilizer or a product in the form...
Patent
1997-10-02
2000-04-25
Kopec, Mark
Compositions
Oxidative bleachant, oxidant containing, or generative
Composition containing a stabilizer or a product in the form...
510309, 510367, 510435, 510478, 510509, 4234152, C01B 1510
Patent
active
060540664
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention relates to a process for the production of a novel sodium percarbonate product which can be used as an active oxygen-containing compound in pH-regulated washing and cleaning agent systems, in particular in the slightly alkaline pH range.
It is well known that peroxy compounds can be used as bleaching compounds in washing agent mixtures in powder form. In the usual household heavy-duty detergents, sodium perborate tetrahydrate or sodium perborate monohydrate is commonly used as the bleaching agent since these materials are relatively resistant to decomposition in pure washing agent media. However, with increasing frequency, other alkali metal peroxy salts, in particular peroxy carbonates such as sodium percarbonate (PCS) are being used. Commonly, PCS is produced e.g. from solutions (wet method). In this connection, it should not be forgotten that it is not a clearly defined homogeneous compound, but a mixture of compounds, some of which contain water of hydration, with e.g. the following formulae: CO.sub.3 .multidot.H.sub.2 O.sub.2 ; from the chemical point of view PCS can therefore be more accurately referred to as sodium carbonate peroxyhydrate.
The use of peroxycarbonate (PCS) in washing agent and cleaning agent systems still causes some problems from the technical point of view of application. It has, for example, been found that the use of peroxycarbonate with the simultaneous application of bleaching agent activators such as TAED (tetraacetylethylenediamine) at a high pH of approximately 11 does not lead to an optimum bleaching effect in certain washing agent systems such as it is obtained, on the other hand, at a low pH of e.g. 8 to 9.
There is consequently a requirement for a sodium percarbonate-containing product which is not easily affected by the pH in modern washing and cleaning agent systems and is consequently able to develop an optimum bleaching effect. Moreover, the product should have a suitable active oxygen content and a good active oxygen stability and storage stability, in particular in the presence of other common washing agent and cleaning agent components.
This object is achieved by the process according to the invention detailed in the patent claims, the product according to the invention and its use according to the invention.
In particular, the invention relates to a process for the production of a mixed sodium percarbonate/sodium bicarbonate compound which is characterized in that a mixture of a starting product containing sodium bicarbonate and of an aqueous hydrogen peroxide solution is reacted with--at least slight--heating and that the mixed sodium percarbonate/sodium bicarbonate compound formed is obtained by simultaneous or subsequent drying. In the present process, products containing sodium bicarbonate which are known as such and are of synthetic or natural origin can be used. In particular, sodium bicarbonate with the formula NaHCO.sub.3 can be used in the process according to the invention with particularly good results; this sodium bicarbonate is also referred to as sodium hydrogen carbonate. To be able to convert the sodium bicarbonate to sodium percarbonate, at least slight heating is required since only a slight reaction of the starting product to form sodium percarbonate is observed on mixing of the sodium bicarbonate-containing starting product with the aqueous hydrogen peroxide solution alone (e.g. at room temperature). Preferably, the mixture is reacted in particular with heating to a temperature of at least approximately 50.degree. C. During this process, a genuine mixture of sodium percarbonate and sodium bicarbonate is formed which essentially contains no other reaction products; for example, a soda content of maximum approximately 1% by wt. has only been found in the present reaction products. Carbon dioxide (H.sub.2 CO.sub.3) which is formed as a further reaction product is removed during the conversion or drying as a gaseous product, e.g. as CO.sub.2, and water. The aqueous hydrogen peroxide solution which is used as further star
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Beck Harald
Fuchs, deceased Paul-Wilhem
Honig Helmut
Mathes Manfred
Kopec Mark
Mruk Brian P.
Solvay Interox GmbH
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