| 摘要 |
720,616. Removing marks from record material ink. NATIONAL CASH REGISTER CO. June 16, 1952 [June 23, 1951 ; June 23, 1951], No. 15058/52. Class 146 (3). Coloured marks made by bringing a record material (e.g. paper) sensitized with an electronacceptor absorbent substance into contact with an organic compound (e.g. crystal violet lactone of malachite green lactone) of formula (where R is a saturated alkyl group containing not more than 4 carbon atoms and X if present is a dialkyl amino group containing not more than 4 carbon atoms in an alkyl group) are removed by applying to the marks an acid which forms a salt with the alkylamino groups. Specified electron acceptor substances are magnesiumtrisilicate, pyrophillite, zirconium or titanium dioxide, attapulgite or sodium aluminium silicate zeolite material in which the base exchange sodium ions may be replaced by nickel, copper, iron, zinc, mercury, barium, lead, cadmium or potassium. Specified acids are acetic, propionic, butyric, ethylhexoic and hydrochloric. The marking organic substance may contain a second compound which oxidises slowly in contact with the absorption surface to give a permanent colour, e.g. tetramethyl or tetraethyl benzidine or benzoyl leuco methylene base, and the two marking substances may be dissolved in a solvent, e.g. chlorinated diphenyl. In this case, non-oxidised substance may be removed by a solvent, e.g. acetone, methyl ethyl ketone or ethyl acetate (with or without benzene or toluene) in which the acid is dissolved. The eradicating solution may be applied by a swab or dropper and excess soaked up. Specification 712,216 is referred to.
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