Percarboxylic acid solutions with improved stability when in contact with stainless steel and process for producing said percarboxylic acid solutions

The process according to claim to 1, further comprising adding at least one stabilizer in a total quantity of up to 0.1 wt. %.

A percarboxylic acid solution with improved stability when in contact with stainless steel, consisting essentially of a percarboxylic acid having 1 to 12 C atoms and one or two peroxycarboxyl groups and a solvent system, wherein said percarboxylic acid solution contains at least one polyphosphoric acid of the formula H.sub.n+2 P.sub.n O.sub.3n+1, in which n denotes the average degree of condensation and is greater than or equal to 2.3, in a quantity of 0.2 to 10 wt. % relative to said percarboxylic acid solution;

• said percarboxylic acid solution produced by a process reacting a carboxylic acid having 1 to 12 C atoms and one or two carboxyl groups with hydrogen peroxide in the presence of a solvent system, an acidic catalyst and optionally at least one stabilizer, at a temperature 0.degree. to 70.degree. C. to produce a reaction mixture containing said percarboxylic acid;
• wherein said catalyst is a polyphosphoric acid of the formula H.sub.n+2 P.sub.n O.sub.3n+1, in which n denotes the average degree of condensation and is greater than or equal to 2.3, in a quantity of 0.2 to 10 wt. % relative to said percarboxylic acid solution.