Process for the preparation of perhydrates |
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| 申请号 | US28512572 | 申请日 | 1972-08-31 | 公开(公告)号 | US3860694A | 公开(公告)日 | 1975-01-14 |
| 申请人 | DU PONT; | 发明人 | JAYAWANT MADHUSUDAN D; | ||||
| 摘要 | A process for producing stable, particular perhydrates of sodium carbonate and phosphates comprising contacting the precursor of the perhydrate with concentrated hydrogen peroxide solution in such quantity as to develop the desired active oxygen content in the particles. The perhydrate is recovered by drying. Stabilizers may be present in the precursor or may be added prior to, with, or after hydrogen peroxide addition. The perhydrate may be agglomerated to meet end-use particle size requirements by contacting the particles with water, optionally containing an agglomerating agent or stabilizer. Reaction and perhydrate uniformity are achieved by balancing water content, reaction conditions, residence time under reaction conditions, and stabilizer content. | ||||||
| 权利要求 | 2. A process of claim 1 wherein the reaction temperature is about 25* to 50*C. 3. A process of claim 1 wherein the particle size is about 30 to 140 U.S. standard sieve number. 4. A process of claim 1 wherein the drying temperature is about ambient to 90*C. 5. A process of claim 1 wherein the stabilizer is magnesium silicate. 6. A process of claim 5 wherein the magnesium silicate is formed in situ. 7. A process of claim 1 wherein the hydrogen peroxide concentration is about 50 to 70 percent by weight. 8. A process of claim 1 wherein the residence period is about 10 minutes to 3 hours. 9. A process of claim 1 comprising the additional step of agglomerating the perhydrate after drying. 10. A process of claim 1 comprising the additional step of adding about 0 to 2 moles of water per mole of precursor prior to the addition of hydrogen peroxide. 11. A process of claim 1 wherein the precursor is sodium carbonate. 12. A process of claim 1 wherein the precursor is selected from the group consisting of the pyrophosphates of sodium, disodium hydrogen phosphate and trisodium phosphate. 13. A process of claim 1 wherein the precursor is a mixture of sodium carbonate and sodium phosphate. 14. The process of claim 1 wherein the stabilizer is incorporated into the hydrogen peroxide with which the particulate precursor is contacted. 15. The process of claim 1 wherein the stabilizer is incorporated into the particulate precursor. 16. THE PROCESS OF CLAIM 1 WHEREIN THE FINAL PRODUCT IS STABILIZED WITH 500 TO 5,000 PARTS PER MILLION BY WEIGHT IS OF SI 17. The process of claim 1 wherein ethylenediamine tetraacetic acid, diethylenetriamine pentaacetic acid, benzoic acid, silica, magnesium stearate, calcium silicate, clays, titanium dioxide, stearic acid amides and stearic acid metal salts are incorporated as additives into the final product at concentrations of from 500 to 10,000 parts per million. 18. The process of claim 17 wherein the additive is added to the particulate precursor. 19. A dry process for the production of a stable perhydrate comprising: a. Forming a moist particulate reaction mass by contacting a particulate precursor selected from the group consisting of sodium carbonate, sodium phosphates, and mixtures thereof, of particle size U.S. standard sieve number 14 to 325 mesh, under agitation and at a reaction temperature of about 20* to 60*C. with aqueous hydrogen peroxide in two stages: in the first stage adding about 5 to 20 percent hydrogen peroxide by weight until up to about 20 percent of the total peroxide requirement has been added while maintaining the water content of the reaction mass below about 20 percent, then in the second stage adding the remaining peroxide requirement as a peroxide solution of about 35 to 90 percent concentration, the total peroxide requirement being added over a period of at least one-Quarter hour; b. Maintaining the reaction mass under the above conditions for a residence period of at least about five minutes after hydrogen peroxide addition is complete; c. Adding water during the residence period to make the water content of the reaction mass during reaction from about 4 to 35 percent based on the dry weight of the reaction mass; d. Stabilizing the final product against loss of active oxygen by incorporating therein a stabilizer selected from the group consisting of magnesium sulfate, magnesium silicate, magnesium chloride, magnesium fluosilicate, magnesium oxide, and magnesium hydroxide, expressed as Mg; sodium silicate, expressed as Si and mixtures thereof so as to introduce into the reaction mass, based on the weight of the dry perhydrate, about 300 to 1200 parts per million by weight of Mg and 200 to 10,000 parts per million by weight of Si and e. Drying the reaction mass. 20. A process of claim 19 wherein the reaction temperature is about 25* to 50*C. 21. A process of claim 19 wherein the drying temperature is about ambient to 90*C. 22. A process of claim 19 wherein the hydrogen peroxide concentration during the second stage is about 50 to 70 percent by weight. 23. A process of claim 19 wherein the particle size is about 30 to 140 U.S. standard sieve number. 24. A process of claim 19 wherein the stabilizer is magnesium silicate. 25. A process of claim 24 wherein the magnesium silicate is formed in situ. 26. A process of claim 19 wherein the residence period is about 10 minutes to 3 hours. 27. A process of claim 19 comprising the additional step of agglomerating the perhydrate after drying. 28. A process of claim 19 comprising the additional step of adding up to 2 moles of water per mole of precursor immediately prior to the addition of hydrogen peroxide. 29. A process of claim 19 wherein the precursor is sodium carbonate. 30. A process of claim 19 wherein the precursor is selected from the group consisting of the pyrophosphates of sodium, disodium hydrogen phosphate and trisodium phosphate. 31. A process of claim 19 wherein the precursor is a mixture of soidum carbonate and sodium phosphate. 32. The process of claim 19 wherein the stabilizer is incorporated into the hydrogen peroxide with which the particulate precursor is contacted. 33. The process of claim 19 wherein the stabilizer is incorporated into the particulate precursor. 34. The process of claim 19 wherein the final product is stabilized with 500 to 5,000 parts per million by weight of Si. 35. The process of claim 19 wherein ethylenediamine tetraacetic acid, diethylenetriamine pentaacetic acid, benzoic acid, silica, magnesium stearate, calcium silicate, clays, titanium dioxide, stearic acid amides and stearic acid metal salts are incorporated as additives into the final product at concentrations of from 500 to 10,000 parts per million. 36. The process of claim 35 wherein the additive is added to the particulate precursor. |
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