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US 5,852,179 AGranted
Preparation of disperse azo dyestuffs in the presence of alkoxylated acetylenic diols
AssigneeAir Products and Chemicals, Inc.
InventorGregory Paul Dado
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AssigneeAir Products and Chemicals, Inc.
InventorGregory Paul Dado
Estimating the term…
The use of alkoxylated acetylenic diol surfactants in the aqueous synthesis of disperse azo dyes provides a simple process for improving filtration properties of dyestuff. The surfactants may be added prior to the coupling step of the synthesis or prior to heat treatment of the dye slurry. Advantages that are realized by incorporation of the surfactants into the synthesis include decreased filtration time, increased solid content in filter cake, improved washing properties of filter cake, and increased dye yield. In addition, for azo dyes that are synthesized as non-heat-stable crystal modifications, the presence of alkoxylated acetylenic diol surfactants in the dye slurry is effective in promoting the conversion of the dye to the desired thermally stable crystal modification.
A process for the preparation of a disperse azo dye by reacting a diazonium salt of an aromatic or heteroaromatic amine with a coupling component in an aqueous media to afford an aqueous slurry of the azo dye and optionally heat treating the aqueous slurry, characterized by incorporating an alkoxylated acetylenic diol into the process.
In a process for the preparation of a disperse azo dye by reacting a diazonium salt of an aromatic or heteroaromatic amine with a coupling component in an aqueous media to afford an aqueous slurry of the azo dye and optionally heat treating the aqueous slurry, the improvement which comprises incorporating into the process prior to the heat treating step an alkoxylated acetylenic diol represented by the general formula:
Dependencies are inferred from the claim text.