Patent ID: 7527657

Claim:
A liquid preparation of a paper dye comprising a) 15 to 20% by weight of the dye of the formula CuPc [SO 2 NH(CH 2 ) 3 N(CH 3 ) 2 ] 2 to 3 [SO 3 H] 1 to 2 (1), in which CuPc represents copper phthalocyanine, or the alkali metal salt of (1), b) 8 to 12% by weight of ∈-caprolactam, c) 2 to 5% by weight of formic acid, d) 4 to 6% by weight of benzyl alcohol, e) 0 to 3% by weight of a lower aliphatic organic acid, f) 0 to 5% by weight of an inorganic salt and g) water, to complete to 100% by weight.