Enhanced antiperspirant salts stabilized with calcium and concentrated aqueous solutions of such salts

A method of preparing an enhanced efficacy aluminum or aluminum-zirconium antiperspirant salt having an HPLC peak 4 to peak 3 area ratio of at least 0.5 with at least 70% of the aluminum contained in said peaks 3 and 4, which method comprises providing an aqueous solution of a non-enhanced aluminum or aluminum-zirconium antiperspirant salt, an effective amount of a soluble calcium salt, and an effective amount of a water soluble amino and/or hydroxy acid, and aging said solution for a time and at a temperature sufficient to convert the non-enhanced aluminum or aluminum-zirconium antiperspirant salt to said enhanced efficacy aluminum or aluminum-zirconium antiperspirant salt.

In a method of making an enhanced efficacy antiperspirant salt of an aluminum hydroxy halide or an aluminum hydroxy nitrate which comprises reacting aluminum with an aqueous solution of aluminum halide or aluminum nitrate or with aqueous hydrogen halide or nitric acid, the improvement wherein said aqueous solution comprises a soluble calcium salt and a water soluble amino and/or hydroxy acid.

A method of making an aqueous solution of an enhanced efficacy aluminum antiperspirant salt of the formula Al.sub.2 (OH).sub.6-a X.sub.a wherein X is Cl, Br, I or NO.sub.3 and a is about 0.3 to about 5, wherein said salt has an HPLC peak 4 to peak 3 area ratio of at least 0.5 with at least 70% of the aluminum contained in said peaks 3 and 4, which method comprises reacting aluminum with an aqueous solution of AlX.sub.3 or HX, wherein the amount of aluminum, the amount of AlX.sub.3 or HX, and the time and temperature of reaction are selected so as to provide said antiperspirant salt of the formula Al.sub.2 (OH).sub.6-a X.sub.a at a concentration of about 5% to about 45% (USP) by weight, and wherein said aqueous solution of AIX.sub.3 or HX additionally comprises a water soluble amino and/or hydroxy acid in an amount to provide an acid:Al ratio of about 2:1 to about 1:20, and a soluble calcium salt in an amount to provide a Ca:Al ratio of about 1:1 to about 1:28.