Security paper for prepn. of official documents etc. - is coated with or contains oxy:pyrene-tri:sulphonic acid or a salt of the acid

摘要

Paper which is secure against forgery, used partic, for making official documents and materials such as cheques, traveller's cheques, and account books, and which can provide against any alteration of the writing, partic. by means of an ink-erasing pencil, contains oxyprene-trisulphonic acid or one of its salts, partic. its Na salt, on the surface of the paper or in its mass. This security paper, which has a good whiteness, is partic. sensitive to erasing pencils which instantly form visible colours on the paper.