Amino acid free stable aluminum/zirconium antiperspirant solution
View Patent ↗An amino acid free stable aluminum zirconium polyhydric alcohol aqueous solution having a high anhydrous antiperspirant solid concentration and a high percentage of low molecular weight aluminum species, i.e., containing 60% or more of band IV peak area based on high pressure liquid chromatography, is prepared by adding a zirconium salt to an aqueous polyhydric alcohol solution of a basic aluminum chloride.
1. A method for preparing a stable aqueous solution of an aluminum zirconium antiperspirant composition having enhanced efficacy by having a high proportion of lower molecular weight aluminum species comprising mixing and reacting a basic aluminum salt polyhydric alcohol aqueous solution with a zirconium compound at a temperature not exceeding 105° C. until a clear solution is attained and filtering the solution.
2. A method according to claim 1 , wherein said polyhydric alcohol (aqueous) solution contains 20 to 55% by weight of an aluminum compound having the formula Al 2 (OH) 6-a X a ·mP·nH 2 O wherein a is a numerical value greater than zero and less than 6.0, X is an ion selected from chloride, bromide, iodine, nitrate, perchlorate or sulfate, P is polyhydric alcohol having at least two carbon atoms and at least two hydroxyl groups, m has a numerical number of about 0.1 to about 1.5 and n has a numerical value of about 0.5 to about 4.
3. A method according to claim 1 , wherein said zirconium complex compound has the formula ZrO(OH) b X 2-b wherein b is a numerical number from 0 to 1.3 and x is a member of the group consisting of chloride, bromide, iodide, nitrate, perchlorate and sulfate ions.
4. The method according to claim 2 wherein the filtered solution has a metal to chloride ratio of 0.9 to 1.2.
5. The method according to claim 4 , wherein said the filtered aluminum zirconium antiperspirant solution has a HPLC Band IV area of about 20 to 75%.
6. The method according to claim 4 , wherein the filtered antiperspirant solution has a HPLC Band IV area of about 45 to 65%.
7. The method according to claim 4 , wherein the solution has 27 Al NMR spectrum wherein 100% of the total area is contained in the range of chemical shift of about 0 to about 10 ppm.
8. The method according to claim 4 , wherein said the stable antiperspirant solution has the Al/Zr ratio of about 0.8 to 10.
9. The method according to claim 3 , wherein said zirconium salt is zirconium oxychloride.
10. The method according to claim 1 , wherein the filtered product solution is dried.
11. The method according to claim 1 , wherein the filtered product is spray dried.
12. The method of claim 1 , wherein the solution is prepared by first pre-mixing in solution a zirconium salt and a polyhydric alcohol and subsequently reacting the thus prepared solution with a basic aluminum salt.
13. The method of claim 1 , wherein a basic aluminum salt solution is pre-mixed with a polyhydric alcohol and the thus prepared solution is reacted in solution with a zirconium compound.