Stabilized aqueous aluminum zirconium solutions
View Patent ↗The present invention describes a method and compositions by which introducing PO 4 −3 ion at particular stage in the preparation of aluminum/zirconium solutions surprisingly results in significantly improved zirconium molecular weight stability.
1. A method of making a stabilized aqueous solution comprising polymerically stable zirconium in a composition comprising aluminum, zirconium, phosphate and chloride, the method comprising the steps of: (a) combining a chloride-containing acid and a source of phosphate ion to form a phosphate mixture wherein the phosphate ion to zirconium ion ratio is approximately 0.02:1-0.151:1 weight/weight; (b) combining the phosphate mixture with a zirconium ion source and mixing well to dissolve; (c) mixing a buffer at a molar ratio of approximately 1:1 with the zirconium; (d) combining the product of step (c) with aqueous aluminum salt to a Al:Zr molar ratio of about 1:1 to about 11:1 and an (Al+Zr):Cl molar ratio of about 0.3:1 to about 2.5:1; and (e) optionally, drying to form a powder thereby producing a polymerically stable zirconium composition.
2. The method of claim 1 wherein the zirconium ion source is a Zr(CO 3 ) 2 paste.
3. The method of claim 1 wherein the zirconium ion source is zirconium oxychloride.
4. The method of claim 1 wherein the buffer is a glycine buffer.
5. The method of claim 1 wherein the phosphate ion is PO 4 −3 .
6. The method of claim 1 wherein the Al:Zr molar ratio is about 1:1 to about 11:1.
7. The method of claim 1 wherein the Al:Zr molar ratio is about 2:1 to about 10:1.
8. The method of claim 1 wherein the (Al+Zr):Cl molar ratio is about 0.3:1 to about 2.5:1.
9. The method of claim 1 wherein the (Al+Zr):Cl molar ratio is about 0.9:1 to about 2.1:1.
10. A composition made by the method of claim 1 .