Patent GB-488656-A (GB)
Title: Improvements in pickling metals
IPC: C23G5/032
Filed: 1936-12-10
Abstract: A composition for cleaning metals such as iron, copper, and their alloys consists of a fatty liquid which contains a pickling agent in solution and which is of less density than water and substantially immiscible therewith.  The liquid may be made into a paste by the addition of an inert powdered material.  The liquid preferably consists of a mixture of an alcohol or phenol, a saturated or unsaturated aliphatic acid, and a pickling acid such as hydrochloric or acetic which is soluble in the alcohol or phenol.  The alcohol may be one or more of amyl, and butyl alcohols and their higher homologues, and the etherified or esterified derivatives of glycols. The aliphatic acid may be, for example, undecylenic acid, oleic acid, or stearic acid. Glycerides may be added to the liquid, and, to prevent action of the liquid or the metal, a small amount of trioxymethylene may be added.  An example of a suitable liquid is 10 per cent of undecylenic acid, 5 per cent of anhydrous acetic acid, 15 per cent of 22 DEG  B<\>ae. hydrochloric acid solution, and 70 per cent of butanol.  U.S.A. Specification 1,993,097 is referred to.  The Specification as open to inspection under Sect. 91 refers also to the use of methyl and ethyl alcohols and glycols as constituents of the liquid.  This subject-matter does not appear in the Specification as accepted.ALSO:Superficial impurities, e.g. oxides, are removed from the surfaces of metals, e.g. iron, copper, and their alloys, by treatment of the surfaces by immersion, spraying, brushing, &c. with a fatty liquid which contains a pickling agent in solution and which is of less density than water and substantially immiscible therewith. The liquid may be made into a paste by the addition of an inert powdered material.  The water &c. produced by the action of pickling agent on the metal and the oxides does not mix with the cleaning liquid and can be withdrawn; the process can be made continuous by using a bath of the liquid, continuously withdrawing any water &c. from the bottom of the bath and continuously feeding regenerating liquid to the bath.  The liquid is preferably formed by mixing an alcohol or phenol, a saturated or unsaturated aliphatic acid, and a pickling acid such as hydrochloric or acetic which is soluble in the alcohol or phenol. The alcohol may be one or more of amyl and butyl alcohols and their higher homologues, and etherified or esterified derivatives of glycols.  The aliphatic acid may be, for example, undecylenic acid, oleic acid, or stearic acid.  Glycerides may be added to the liquid, and, to prevent action of the liquid on the metal, a small amount of trioxymethylene may be added.  An example of a suitable liquid is 10 per cent of undecylenic acid, 5 per cent of anhydrous acetic acid, 15 per cent of 22 DEG  B<\>ae. hydrochloric acid solution, and 70 per cent of butanol.  The liquid may be used hot or cold, and after pickling the metal is washed e.g. with water, benzene, or a mixture of petrol and alcohol, and may be neutralized with a bath of lime water, sodium carbonate, &c. U.S.A. Specification 1,993,097 is referred to.  The Specification as open to inspection under Sect. 91 refers also to the use of methyl and ethyl alcohols and glycols as constituents of the liquid.  This subject-matter does not appear in the Specification as accepted.