Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With oxygen or halogen containing chemical bleach or oxidant...
Patent
1996-10-01
1997-10-28
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, 25218627, 25218629, 25218632, C01B 1510, C11D 339, C11D 1700
Patent
active
056818076
DESCRIPTION:
BRIEF SUMMARY
The invention relates to the use of lactobionic acid, lactobionic acid salts and/or lactobionic acid derivatives as a coating material for coating particulate alkali metal peroxy salts, a process for the preparation of coated particulate alkali metal peroxy salts in which lactobionic acid, a lactobionic acid salt and/or a lactobionic acid derivative are used as coating material for coating the alkali metal peroxy salt particles and, additionally, the coated, particulate alkali metal peroxy salts obtained according to the preceding process and their application.
It is well known that peroxy compounds can be used as bleaching compounds in detergent mixtures in powder form. In the usual heavy duty detergents for household use, sodium perborate tetrahydrate or sodium perborate monohydrate are usually used as bleaching agents since these materials are relatively resistant to decomposition in a pure detergent medium. However, use is made of other alkali metal peroxy salts, in particular peroxycarbonate (percarbonate) with increasing frequency. These alkali metal peroxy salts, percarbonate in particular, are stable in the pure dry state; however, they have the disadvantage of decomposing easily in the presence of moisture with loss of active oxygen; this will be illustrated in further detail below by way of the example of percarbonate, particularly sodium percarbonate (PCS).
The above disadvantages are attributable in particular to the fact that percarbonate can never be entirely dry since, apart from the residual water from the production process, water is always formed by decomposition of hydrogen peroxide in the PCS itself. During the preparation of PCS from solutions (wet process), it must also be remembered that, instead of a well defined, homogenous compound, a mixture of compounds, some of them containing water of hydration, with the following formula are obtained: not only from the base powder by way of which a major part of the moisture is introduced into the detergent composition via the individual components such as zeolite, carboxymethylcellulose, soda, optical brighteners etc. but a percentage of the undesirable moisture consequently originates from the percarbonate itself. For this reason, an optimum coating layer for alkali metal peroxy salts, in particular for percarbonate, ought to keep off not only the moisture affecting the percarbonate particle from outside, but it ought to simultaneously be capable of sufficiently protecting the percarbonate against the water of crystallization formed from the percarbonate itself and/or the moisture of decomposition. In addition, the coating material used for coating the PCS particles ought not to impede the rate of dissolution of the percarbonate. Apart from their protective and coating function, the coating materials used should be able to accomplish additional tasks in ready-to-use composition containing the coated alkali metal peroxy salt.
To stabilize alkali metal peroxy salts, it had previously been suggested according to the state of the art to coat alkali metal peroxy salts, e.g. with inorganic stabilizing materials or mineral protective films.
German Offenlegungsschriften 33 21 082 and 33 48 394, for example, describe the use of borate which may additionally contain an alkali metal silicate as coating agent for coating percarbonate. A similar coating material of different boric acids, if necessary again containing alkali metal silicate, is described in German Offenlegungsschrift 28 00 916. Mineral salts are also recommended as coating materials according to the state of the art. German Offenlegungsschrift 29 15 980, for example, describes coating of sodium percarbonate with alkaline earth metal salts which are applied onto the sodium percarbonate particles from an aqueous solution. Moreover, German patents 24 17 572 and 26 22 610 describe the stabilization of alkali metal peroxy salts by coating with a mineral protective film of sodium carbonate with other mineral salts, in particular with sodium sulphate. According to German patent 26 22 610, this m
REFERENCES:
patent: 5069808 (1991-12-01), Gerling et al.
Doetsch Werner
Gerling Klaus-Guenter
Hecken Gerd
Honig Helmut
Mathes Manfred
Einsmann Margaret
Solvay Interox GmbH
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