Dyestuff prepn. (I) is obtd. by homogenising, without subdivision into fine particles, a mixt. of an organophilic dyestuff (II) of m.pt. = 140 degrees C and a polar-non-polar emulsifier (III). (I) are used for optical bleaching, dyeing and printing: mainly of linear polyesters but, also for cellulose esters, and synthetic polyamides. They can also be used or mixed fibres e.g. polyamide and polyester; cotton and polyester; or wool and polyester. (I) are very easily prepd. and are highly dispersion stable. They need no non-biodegradable dispersing agents added, nor any costly fine subdivision grinding treatment. Pref. (II) have m.pts. =100 degrees C and carry hydrophilic substits. esp. such as CO2H, CO2R, OCONHR or -(C2H4O)nR" where R is (ar)alkyl or aryl opt. substd., R" is H, acyl or R and n is 1-8. (II) carry no ionising gps. other than carboxyl. (II) esp. have formula E(G1)x Ry where E may be any usual chromophoric or optical bleaching gp.; G1 is a direct link or a polyvalent (at least divalent) bridging gp. stable under the dyeing conditions employed; and R, acting as the m.pt. lowering component and/or conferring the hydrophilic charade (II), is a 5-10C hydrocarbon or a polyoxyalkylene of 2-10 oxyalkylene units, x and y are 1-4, esp. 1-2.
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