Halftone gravure printing inks containing pyridone azo dyestuffs

A dyestuff which is obtained by reacting a pyridone azo dyestuffs of the formula ##STR52## in which D denotes the radical of a diazo component,

• T.sub.1 denotes alkyl, aryl or --COOT.sub.4,
• T.sub.2 denotes H, --CN, --COOT.sub.4 or --CONH--T.sub.5 (OH).sub.n,
• T.sub.4 denotes hydrogen or alkyl,
• if n is 0, T.sub.3 and T.sub.5 each independently represent C.sub.1 -C.sub.22 -alkyl, C.sub.2 -C.sub.22 -alkenyl, C.sub.3 -C.sub.7 -cycloalkyl, benzyl, phenethyl, C.sub.2 -C.sub.18 -alkoxyalkyl, phenoxy-C.sub.1 -C.sub.22 -alkyl or phenoxy-C.sub.2 -C.sub.18 -alkoxy? alkyl and if n is 1, 2, 3 or 4,T.sub.3 and T.sub.5 each independently represent a C.sub.2 -C.sub.18 -alkyl or C.sub.2 -C.sub.18 -alkyl which is interrupted by 1-6 oxygen atoms and
• m and n denote 0, 1, 2, 3 or 4, subject to the proviso that the sum of m+n is 1, 2, 3 or 4, with oxalic acid or a carboxylic acid of the formula
• [G']-(COOH).sub.a
• in which G' denotes an aliphatic or aromatic hydrocarbon radical having 1-51 carbon atoms and a denotes 2, 3 or 4 or a carboxylic acid of the formula
• [G"]-(OCH.sub.2 CH.sub.2 -COOH).sub.a '
• in which G" denotes a saturated or unsaturated hydrocarbon radical having 2 to 20 carbon atoms or a saturated or unsaturated hydrocarbon radical in which the carbon chain can be interrupted by 1-9 non-adjacent oxygen atoms and a' denotes 2, 3, 4 or 5 to form an ester linkage between at least two identical or different pyridone azo dyestuffs.