GB1063771A - Electrolytic recording media - Google Patents

Abstract

An electrolytically conducting aqueous solution, for use in the production of electrolytic recording media, is on the acid side of neutrality, and is made up by mixing a marking compound, an electrolyte and a tetraborate sensitizer. The marking compound is aromatic and has at least two functional groups on the nucleus, at least one of these groups being hydroxyl. The recording medium comprises a porous support, e.g. paper, impregnated with the solution. Optional ingredients are a stabilizer, an antifringing agent, an acidifier, and an oxidant. Specific materials referred to are: as tetraborate-the sodium and potassium salts and their hydrates; as marking compound-catechol, gallic acid, methyl gallate, gallamide, tannic acid, pyrogallol, aminophenols, organic acids and aldehydes having a polyhydroxylated phenyl group in the molecule, reduced quinones, e.g. hydroquinone, and derivatives of the above such as esters and amides of the acids or oximes of the aldehydes or aryl-alkyl-or aralkyl-substituted analogues of the amino-phenols, acids, aldehydes or their derivatives, hydroquinone, salicylaldoxime, salicylic acid, salicylic aldehyde, O-aminophenol, hydroxylated aminotoluidines and protocatechnic acid; as electrolyte-sodium and potassium chlorides, bromides and nitrates; as stabilizer-thiourea, alkyl derivatives of thiourea, e.g. N-ethyl-thiourea, and dithiobiuret; as anti-fringing agent-alkali-metal phosphates and pyrophosphates; as acidifier-oxalic, sulphuric, nitric, hydrochloric, citric, formic, itaconic and maelic acids; and as oxidantpotassium chlorate.