PREPARATION OF FINE PARTICULATE HEATTRESISTANT BENZOTHIAZOLE AZO DYE

摘要

PURPOSE:To rearrange the beta-form crystal of a specific benzothiazole azo dye to the alpha-form crystal stable to heat efficiently, by heat-treating the beta-form crystal in the presence of an anion dispersing agent under specific conditions. CONSTITUTION:(A) A mixture of 2-amino-5,6-dichlorobenozthiazole with 2-amino- 6,7-dichlorobenzothiazole is diazotized and coupled with N-ethyl-N-beta-cyanoethylaniline or (B) the mixture is diazotized and coupled with N-ethyl-N-beta-cyanoethyl- m-toluidine to give a wet azo dye cake of the beta-form crystal unstable to heat. The resultant wet cake is heated in an aqueous medium containing an anion dispersing agent and if necessary a nonionic surfactant at 80-100 deg.C to convert the beta-form crystal to the alpha-form crystal having improved heat resistance. USE:Dyeing a polyester fiber.