Degussa Aktiengesellschaft

Thomas Lieser

Birgit Bertsch-Frank

Klaus Mueller

Martin Bewersdorf

Claas-Juergen Klasen

Gunter Prescher

Manfred Dankowski

Wolfgang Leonhardt

Manfred Diehl

Claas-Jurgen Klasen

Peter Schubert

Petra Look-Herber

Joerg Herzig

Wolfgang Zikofsky

Klaus Muller

Juergen Rollmann

Coated sodium percarbonate particles contain, in the coating, sodium carbonate and also one or more magnesium compounds, preferably magnesium sulfate, optionally in a partially hydrated form, in a single layer or in separate layers in the coating. Preferred coated sodium percarbonate particles contain two layers. Particles are prepared by spraying aqueous solutions containing the coating components onto sodium percarbonate in a fluidized bed with simultaneous evaporation of the water. The particles are suitable for use in detergents, bleaches and cleansing agents.

Coated sodium percarbonate particles, a process for their preparation

Coated sodium percarbonate particles, a process for their production and

Method for the preparation of stabilized sodium percarbonate

Sodium percarbonate is produced by means of fluidized bed granulation. The process includes spraying an aqueous sodium carbonate solution and a hydrogen peroxide solution onto nuclei in a fluidized bed and evaporating the water. In the process of the invention, it is not necessary to use a phosphorus-containing crystallization inhibitor in order to avoid cloggings and incrustations in and on the nozzle. This is accomplished by spraying the solutions through separate channels in a single ternary atomizer nozzle, to provide external mixing of the solutions with respect to the nozzle.

Method for producing granulated sodium percarbonate

The invention relates to sodium perborate hydrate granulates and a method for producing sodium perborate hydrate granulates with an available oxygen content of 14 to 18% by weight, especially 15 to 16% by weight; an abrasion index according to ISO test 5937 of not more than 10%; with a rate of dissolution of below 1.5 minutes, preferably below 1.0 minutes (for 1 gram of the granulate in 500 cm.sup.3 water, at 15.degree. C.); and with a bulk weight in the range of 0.6 to 1.2 kg/dm.sup.3. The sodium perborate hydrate granulate can be produced by compacting spray-dried, essentially amorphous sodium perborate hydrate starting material which exhibits a bulk weight below that of the granulate product, and a particle size of 90% less than 100 micrometers. The hydrate starting material is further characterized in that it loses 0.2 to 2.0% of its weight when stored at 60.degree. C. and 100 Pa for 30 minutes. The starting material is compacted between rollers at a contact pressure of 5.times.10 to 2.times.10.sup.4 N/cm, and the resultant product is comminuted and the granulate is sieved according to particle size. The compacted granulate particles may be rounded off by means of a mechanical stressing prior to the sieving step. This method produces granulates with the above-mentioned characteristics which are desired in the market. The granulates are produced in a simple manner, without thermal stressing of the perborate.

Method for the production of sodium perborate hydrate granulates

The spray drying of a solution containing hydrogen peroxide and sodium metaborate to obtain primary particles which are immediately conveyed after leaving the drying zone to a granulating device and are then granulated in the presence of free and/or perborate water of crystallization. The granulated materials are dried, if necessary. The generally amorphous primary particles are converted into granulated materials with at least partially crystalline structure and significantly improved shelf life. The work is performed with advantage in a spray dryer with integrated fluid bed or in a compressing granulating device. The method is suitable for preparing perborate granulated materials with an active oxygen content of over 10% by weight, especially perborate monohydrate granular materials with 14 to 16% by weight active oxygen. A rapidly dissolving product is produced with an acceptable apparent weight for ease in packaging.

High active oxygen content granulated sodium perborate product and

The spray drying of a solution containing hydrogen peroxide and sodium metaborate to obtain primary particles which are immediately conveyed after leaving the drying zone to a granulating device and are then granulated in the presence of free and/or perborate water of crystallization. The granulated materials are dried, if necessary. The generally amorphous primary particles are converted into granulated materials with at least partially crystalline structure and significantly improved shelf life. The work is performed with advantage in a spray dryer with integrated fluid bed or in a compressing granulating device. The method is suitable for preparing perborate granulated materials with over 10% by wt., especially perborate monohydrate granular materials with 14-16% by wt. active oxygen.

Continuous method for preparation of granulated sodium perborate

Aqueous bleaching agent suspensions based on a water-soluble peroxycarboxylic acid suspended in a carrier liquid in the presence of an organic thickening agent and of an acidifying agent exhibit an improved storage resistance over known suspensions with this base. This is achieved by means of pourable to pasty bleaching agent suspensions which contain a xanthan polysaccharide or agar polysaccharide as thickening agent and, in addition, a hydrate-forming neutral salt which desensitizes peroxycarboxylic acids. Preferred suspensions exhibit a pH of 2-5 and contain 10-30% by wt. diperoxydodecanedioic acid, 5-20% by wt. sodium sulfate and 0.1-1.0% by wt. xanthan. The use of non-dried, hydrophilized and optionally in situ desensitized peroxycarboxylic acids is especially preferred. The bleaching agent suspensions are prepared by homogeneously suspending the peroxycarboxylic acid in the thickened carrier liquid. The storage-resistant bleaching agent suspensions are used as laundry bleaching agents and for preparing cleaning agents and disinfection agents.

Aqueous bleaching agent suspensions containing peroxycarboxylic acid,

Aqueous bleaching agent suspensions based on a water-insoluble peroxycarboxylic acid suspended in a carrier liquid in the presence of a colloidal silicic acid and of an acidifying agent which exhibit, in comparision to known suspensions with this base, an improved storage resistance and are more economical to prepare. This result is achieved by means of pourable-to-pasty bleaching agent suspensions which contain 0.1 to 9% by weight silicic acid in relation to the suspension and contain a hydrate-forming neutral salt which desensitizes peroxycarboxylilc acids, in an amount of 10 to 400% by weight, calculated hydrate-free and in relation to peroxycarboxylic acid added. Preferred bleaching agent suspensions contain 10-30% by weight diperoxydodecanedioic acid, 5-20% by weight sodium sulfate and 2 to 6% by weight pyrogenic silicic acid, each in relation to the suspension. The use of non-dried, hydrophilized and optionally in situ-desensitized peroxycarboxylic acids is especially preferred. The preparation of the bleaching agents is performed by homogeneously suspending the peroxycarboxylic acid in the thickened carrier liquid. The storage-resistant bleaching agent suspensions find application as laundry bleaching agents and for the preparation of cleaning and disinfecting agents.

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Hanau, Germany

Thomas Lieser