Process for producing a percarbonate
First Claim
1. Dry particulate sodium percarbonate having:
- (a) a mean particle size of 500 μ
m to 1200 μ
m; and
(b) a seven day aged heat emission in 16 hours at 40°
C. of below 3 μ
W/g.
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Accused Products
Abstract
Sodium percarbonate is traditionally made in a crystallization process from aqueous hydrogen peroxide and sodium carbonate with recycle of mother liquor in the presence of a substantial concentration of a salting out agent, conventionally sodium chloride.
The invention provides a process intended to be conducted without addition of chloride salting-out agent in which the dissolution step is controlled to restrict the sodium carbonate concentration to below 95%, preferably 60 to 90% of its saturated concentration at a temperature preferably controlled to at most 35C. and the mole ratio of hydrogen peroxide:sodium carbonate in the reaction vessel is controlled to between 0.7 to 1.2:1, and preferably about 1:1.
In some embodiments at least a fraction of the mother liquor introduced into the dissolution tank is obtained by extraction from the reaction vessel and in other embodiments a fraction of the sodium percarbonate is introduced in solution in the mother liquor and a fraction is introduced in particulate form directly into the reaction vessel.
Large particle sodium percarbonate is provided which has a 7 day aged heat emission at 40C. of not more than 3 μW/g measured in a microcalorimeter over 16 hours that is lower than the heat emission from conventionally produced sodium percarbonate employing a chloride salting-out agent.
4 Citations
18 Claims
-
1. Dry particulate sodium percarbonate having:
-
(a) a mean particle size of 500 μ
m to 1200 μ
m; and
(b) a seven day aged heat emission in 16 hours at 40°
C. of below 3 μ
W/g. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
-
Specification