Concentrated aqueous dye compositions containing a low molecular weight amide and their use for dyeing paper

Claim 1

In a process for producing colored paper comprising incorporating into paper stock an effective amount of a dye composition and forming paper from said paper stock said effective amount being an amount sufficient to impart the desired color to the paper, the improvement wherein the dye composition is a concentrated, liquid dye composition comprising (i) 1 part by weight of a dye or a mixture thereof, (ii) 0.5-5 parts by weight of urea and (iii) 1 to 8 parts by weight of water, wherein said dye is a dye of the formula R.sub.11 --N= N--R.sub.13 --A--R.sub.14 --N=N--R.sub.12 or K.sub.1 --N=N--B--N=N--K.sub.2, or a salt thereof, wherein each of R 11 and R 12 is independently ##STR21## wherein R 21 is hydrogen, methyl or methoxy, and n is 1 or 2, ##STR22## wherein R 22 is hydrogen or methoxy, and R 23 is hydrogen or methyl, ##STR23## wherein R 22 is hydrogen or methoxy, and R 23 is hydrogen or methyl, A is --NH--, --NH--CO--NH--, trans--NH--CO-- CH=CH--CO--NH-- or ##STR24## wherein R 24 is hydrogen, phenyl or 3-sulfophenyl, each of K 1 and K 2 is independently ##STR25## wherein R 25 is --NH 2 or --OH, and ##STR26## wherein each R 26 is hydrogen, methyl or methoxy.