Patent ID: 7153495

Claim:
A process for preparing stable, low iron, amino acid free aluminum zirconium aqueous antiperspirant compositions having a trace impurity level of each metal (Co, Cr, Ni, Mn, Cu) of less than 2 ppm and having an anhydrous solids content of at about 25% to about 35% which comprises: (i) heating aqueous solution of a low iron basic aluminum halide compound having an iron content of less than 30 PPM and having anhydrous solids content up to and including about44% and represented by the general empirical formula Al 2 (OH) (6-x) Yx.nH 2 O wherein Y is Cl, Br, or I and 0≦x≦6 and n is about 0.8 to 4 and at reflux temperature; (ii) admixing said compound at reflux with an amino acid free zirconium compound at a rate to maintain the refluxing solution substantially clear, said zirconium compound being selected from (a) those having the general formula ZrO(OH) 2-nz B z wherein z may vary from 0.8 to 2 and n is the valance of B and 2-nz is greater than or equal to 0 and B is selected from the group consisting of halides or nitrate; (b) those having the formula [ZrO(OH)(CO 3 ) 0.5 .nH 2 O] and [Zr 2 (OH) 4 (CO 3 ) 2 .nH 2 O]; (iii) refluxing the admixed solution for about 1–2 hours following the completion of the addition of zirconium compound, (iv) cooling the solution to room temperature, (v) and filtering it to give a clear aqueous solution of an antiperspirant salt.