GB845670A - Anionic antiperspirant - Google Patents

Abstract

The invention comprises a process for the preparation of an anionic antiperspirant characterised by the step of forming a mixture of an aqueous solution of a compound which is an alkali metal or ammonium aluminate or an aluminium chlorhydroxy complex containing approximately 1,5-2,5 atoms of aluminium for 1 atom of chlorine, with a non-toxic aluminiumchelating water-and alcohol-soluble aliphatic hydroxycarboxylic acid wherein at least one hydroxy group is alpha or beta to the carboxylic group, the proportion of said acid being less than will take up all available co-ordinating positions of the aluminium, the concentration of alkali metal or ammonium aluminate being not more than 2,5 parts calculated as Al2O3 for 100 parts of the mixture, adjusting the mixture to a pH of 4-9, and reacting the mixture at not above 75 DEG C. until the resulting product when tested with an ionic precipitant for aluminium, such as ammonia or a soluble soap, shows no precipitation at a pH of 4-9 : and the anionic antiperspirant obtained thereby. By preparing the product as above at a pH of 8-9, incorporating therewith a warm alcoholic solution of a fatty acid soap and cooling to form a gel, an anionic antiperspirant in stick form is obtained. Specified hydroxycarboxylic acids are lactic, tartaric, glycollic and gluconic acids.ALSO:An anionic antiperspirant stick having a pH of 8-9 comprises a gelled alcohol solution of an alkali metal soap and a complex of a compound selected from aluminium chlorhydroxy complexes containing approximately 1,5-2,5 aluminium atoms for each chlorine atom, or alkali metal or ammonium aluminates, with an aluminiumchelating non-toxic water- and alcoholsoluble aliphatic hydroxycarboxylic acid, wherein at least 1 hydroxy group is alpha or beta to the carboxylic group, the propertion of the hydroxycarboxylic acid being less than will take up all available co-ordinating positions of the aluminium, and the concentration of the alkali metal or ammonium aluminate being not more than 2,5 parts calculated as aluminium oxide for 100 parts of the complex. Specified hydroxycarboxylic acids are lactic, tartaric, glycollic and gluconic acids. Preferably the preparation of alcohol in the stick is 30-40% by weight; preferably also the proportion of aluminium in the stick is 2,5-7% calculated as Al2O3. The aluminium complexes described above may be dispersed in water and/or alcohols and used as sprays; specified alcohols are ethanol, isopropanol, propanol and propylene glycol. The compositions of the invention may contain perfumes and humectants (such as propylene glycol, sorbitol or glycerine).