Patent GB-492526-A (GB)
Title: Improvements in removing rust or iron-mould and preparations therefor
IPC: C11D3/33
Filed: 1937-03-17
Abstract: Rust and other metal oxide coatings are removed from metal surfaces, and iron mould is removed from fabrics, by treating with a water-soluble amino-carboxylic acid containing one or more basic nitrogen atoms which or each of which is bound to at least two organic residues, each containing a carboxyl group in the a -position to the N atom, or with a water-soluble salt of such an acid. Amino-acids specified are, nitrilo-triacetic acid, ethylene bis(imino-diacetic acid), anthranilic acid N-di-acetic acid, C-dimethyl-nitrilo triacetic acid, C-phenyl-nitrilo-triacetic acid, N-(1-carboxy cyclohexyl)-imino diacetic acid, imino-diacetic acids in which the hydrogen atom of the imino-group has been exchanged for an alkyl, aryl, aralkyl, or hydroxy-alkyl group; amino-acids obtained by reacting 1 molecular proportion of hydrazine, polyamine or hydroxylamine with several of chloracetic acid.  These are preferably used in alkaline solution, and there may be added polishing powders or agents having abrasive action, salts, and emulsifying agents, and in the case of treating rust, reducing agents such as sodium hyposulphite, sodium sulphide, and p  grape sugar.  In examples of metal polishes, (1) kieselguhr is made into a paste with a solution containing dextrin, and the sodium salt of nitrilo-triacetic acid, (2) soap is mixed with tripoli, rouge, water and the sodium salt of ethylene diamino-tetra acetic acid, (3) carbon tetrachloride is emulsified with an aqueous solution containing ammonium oleate and the sodium salt of nitrilo-triacetic acid, (4) White oil is mixed with alcohol, the di-sodium salt of nitrilo triacetic acid, bentonite, water, borax, siliceous chalk, rosin and dilute ammonia. A rusty plate is cleaned by treating with a boiling solution of sodium nitrilo-triacetate to which sodium hyposulphite or grape sugar is added preferably in small amounts.  A cotton fabric is freed from stains of iron mould, by treating with an aqueous solution containing sodium hyposulphite and sodium nitrilo-triacetate or ethylene bis-(imino diacetic) acetate, preferably a little ammonia is added. Bath sponges may also be freed from iron-mould stains in this manner. Specification 474,082 is referred to.ALSO:Rust and other oxide coatings are removed from metal surfaces, by treating with a water-soluble amino-carboxylic acid containing one or more basic nitrogen atoms which or each of which is bound to at least two organic residues each containing a carboxylic group in the a -position to the N atom, or with a water soluble p  salt of such an acid.  Amino acids specified are, nitrilo-triacetic acid, ethylene bis(imino-diacetic) acid, anthranilic acid N - di-acetic acid, C-dimethyl-nitrilo triacetic acid, C-phenyl-nitrilo-triacetic acid, N - (1-carboxycyclohexyl) imino-diacetic acid, imino-diacetic acids in which the hydrogen atom of the imino groups has been exchanged for an alkyl, aryl, or aralkyl, or hydroxy alkyl group; amino acids obtained by reacting 1 molecular proportion of hydrazine, hydroxylamine or a polyamine with several of chloracetic acid.  These are preferably used in alkaline solution and there may be added polishing powders or agents having abrasive action, salts, emulsifying agents and solvents.  In the removal of rust, reducing agents such as sodium sulphide, sodium hyposulphite or grape sugar may be added.  In examples, (1) copper plates are cleaned by treating with a mixture of kieselguhr, dextrin and sodium nitrilo-triacetate, (2) rusty tin plates are immersed in a boiling solution containing sodium nitrilo-triacetate to which grape sugar or sodium hyposulphite is added preferably in small amounts, (3) a mixture, prepared by emulsifying oleic acid with a solution of sodium nitrilo-triacetate containing ammonia, and adding alcohol, sangaj oil, ammonia, and kieselguhr, is spread over a rusty plate by brushing and rubbing, whereby the rust is removed.  Specification 474,082, [Group III], is referred to.