Patent ID: 7029502

Claim:
An azo dye of formula wherein D is 2-trifluoromethyl-4-nitrophenyl, 2-cyano-4-nitrophenyl, 2-trifluoromethylphenyl, 2-trifluoromethyl-4-chlorophenyl, 2-cyano-4-nitro-6-chlorophenyl, 2-trifluoromethyl-4-nitro-6-bromophenyl, 2-phenoxysulfonylphenyl, 2-cyano-4-nitro-1-naphthyl, 2-nitro-4-phenylaminocarbonylphenyl, 2-(N-phenyl-N-ethylaminosulfonyl)phenyl, 2-nitro-4-phenoxysulfonylphenyl, 2-chloro-4-methylsulfonylphenyl, 2-phenylsulfonylphenyl, 2-nitro-4-methylsulfonylphenyl or 3,5-dicyano-4-methyl-2-thienyl and R 1 and R 2 are m-tolyl, o-tolyl, p-tolyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 2,5-dimethylphenyl, mesityl or 4-methoxyphenyl.