Patents Assigned to E. Merck A. G.
  • Non-bleeding indicator and dyes therefor
    Patent number: 4029598
    Abstract: In indicators comprising a carrier such as cellulose saturated with one or more azo dyes having reactive groups capable of forming a chemical bond with the carrier material, the improvement wherein the indicator is made non-bleeding by using such dyes which, in addition to the reactive group, contain at least one additional sulfonic acid and/or carboxylic acid group, an example of such a dye being 4-anilino-3'-(2-hydroxysulfonyloxyethylsulfonyl)-azobenzene-6'-carboxylic acid.
    Type: Grant
    Filed: March 14, 1969
    Date of Patent: June 14, 1977
    Assignee: E. Merck A. G.
    Inventors: Karlheinz Neisius, Wilhelm Baumer
  • Non-bleeding indicators and dyes therefor used in pH determination process
    Patent number: 4029597
    Abstract: In colorimetric indicators comprising a carrier such as cellulose saturated with one or more azo dyes having reactive groups capable of forming a chemical bond with the carrier material, the improvement wherein the indicator is made non-bleeding by using such dyes which, in addition to the reactive group, contain at least one additional sulfonic acid and/or carboxylic acid group, an example of such a dye being 4-anilino-3'-(2-hydroxysulfonyloxyethylsulfonyl)-azobenzene-6'-carboxylic acid.
    Type: Grant
    Filed: August 6, 1975
    Date of Patent: June 14, 1977
    Assignee: E. Merck A. G.
    Inventors: Karlheinz Neisius, Wilhelm Baumer