Water Solubilized Dyes
Original Publication Date: 1978-Jan-01
Included in the Prior Art Database: 2005-Feb-20
Water-solubilized forms of bisdithiobenzoin nickel are useful as optical character readable dyes for use in inks that are invisible to the human eye. In particular. the tetraglyceryl ether, the tetraacetic acid ether, the tetrabutanoic acid ether, and the diacid of the bridged ortho-phenylenediamine nickel complex are useful chromophores. The materials have large extinction coefficients in the near infrared and negligible absorption in the visible region of the spectrum. When so desired, these dyes may be mixed with visible dyes to produce inks both machine- and eye-readable.