| 摘要 |
Dyes containing both azo groups and disulphide groups are prepared by diazotization and coupling using components containing a reducible disulphide (-S-S-) linkage or by reduction and subsequent oxidation of an azo dye containing a thiocyano group. The specified dyes may be prepared by reduction and oxidation of 5-thiocyano-2-amino-toluene--> b -naphtol; reducing p-introaniline --> 1-phenyl-3-methyl-5-pyrazolone, diazotising and coupling to half a mole b -hydroxynaphthoic acid dithioanilide; coupling tetrazotized 4, 41-diaminodiphenyldisulphide to 2 mols of 1-phenyl-3-methyl-5-pyrazolone; and in the examples other similar mono- and disazo dyes are prepared.ALSO:Textile fibres are dyed in the following steps: padding with an aqueous composition comprising azo-disulphide dyestuff pigment and optionally a sulphur dye in reduced or non-reduced form which may be water-soluble or in pigment form, reducing the dyestuff oxidising, scouring and drying the fibres. As azo-disulphide dyes there are used dyes containing a reducible disulphide group (-5-5-) connected between aromatic nuclei as well as azo groups (-N=N-), also dyes which upon reduction and oxidation form such dyes. Examples of suitable dyes are 3 : 31-dimethyldiphenyldisulphide-4 : 41-bis-(azo-b -naphthol), 5-thiocyano-2-amino-toluene --> b -naphthol and the dyestuff formed by reacting m-nitro-aniline-->3-methyl-5-pyrazolone with 1 mol 2 : 4 : 6-trichloro-s-triazine and reacting the condensation product with 0.5 mole 4 : 41-diaminodiphenyl disulphide. A number of modes of operation are described which comprise (a) applying the dye composition, drying, applying the reducing agent, steaming, optionally washing, exidising and finishing and (b) applying the dye composition containing a reducing agent, steaming and proceeding as in (a). The specified reducing agents are sodium sulphide, polysulphide and sulphydrate as well as alkaline solutions of thiourea, sodium s-sodiocarboxymethyl thiosulphate, HOOC-R1-S-CS-S-R2-COOH (R1CR2 being alkylene). The oxidising bath may have a pH of 4-6 and contain sodium bichromate and means for removing H2S gas may be required in some cases. Examples of dyeing cotton, viscose and nylon fabrics are given and an apparatus for a mode of continuous operation is described.
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