Degussa Aktiengesellschaft

Joerg Herzig

Birgit Bertsch-Frank

Thomas Lieser

Wolfgang Zikofsky

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.

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Maintal, Germany

Joerg Herzig