Process for dyeing fibre materials

Process for dyeing hydrophobic fibre materials, preferably polyester fibres, using dyestuffs of the formula ##STR1## wherein THE AROMATIC RINGS A and B can be further substituted, PA1 The azo group is in the meta-position or para-position relative to the amino group of the diphenylamine and the phenolic hydroxyl group is in the ortho-position or para-position relative to the azo group. These dyestuffs are distinguished by high drawing power and good building up and fastness properties.

The subject of the invention is a process for dyeing hydrophobic fibre 
materials, which is characterised in that dyestuffs of the formula 
##STR2## 
wherein THE AROMATIC RINGS A and B can be substituted by halogen, alkyl, 
alkoxy, cycloalkyl or aryl, 
The azo group is in the meta-position or para-position relative to the 
amino group of the diphenylamine and the phenolic hydroxyl group is in the 
ortho-position or para-position relative to the azo group, 
Are used. 
Some of the azo compounds to be used according to the invention are known; 
for example compounds of this type are mentioned in DOS (German Published 
Specification) No. 2,249,643 as intermediate products for acid dyestuffs. 
Surprisingly, it has now been found that they can also excellently be used 
as disperse dyestuffs and in this case are distinguished by a good uptake 
and build-up power and by a good level of fastness properties. 
In the abovementioned formula (I), alkyl preferably denotes alkyl radicals 
with 1-4 C atoms which optionally can also be monosubstituted by cyano, 
halogen, such as chlorine, bromine or fluorine, hydroxyl or C.sub.1 
-C.sub.4 -alkoxy; examples which may be mentioned are: methyl, ethyl, 
n-propyl, iso-propyl, n-butyl, tert.-butyl, cyanoethyl or 2-chloroethyl. 
Suitable aryl is, in particular, phenyl which is optionally monosubstituted 
to trisubstituted by halogen, C.sub.1 -C.sub.4 -alkyl or C.sub.1 -C.sub.4 
-alkoxy; phenyl, tolyl and chlorophenyl are preferred. 
Suitable alkoxy is, in particular, C.sub.1 -C.sub.4 -alkoxy. 
Suitable halogen is chlorine, bromine and fluorine, but preferably 
chlorine. 
Suitable cycloalkyl is, for example, cyclopentyl, cyclohexyl and 
cycloheptyl. 
Dyestuffs to be used particularly preferentially are those which correspond 
to the formula 
##STR3## 
wherein R.sub.1 and R.sub.2 independently of one another represent 
hydrogen, chlorine, methyl, ethyl, methoxy or ethoxy and 
R.sub.3 and R.sub.4 independently of one another represent hydrogen, 
chlorine, methyl, ethyl, propyl, butyl, methoxy, ethoxy, cyclohexyl or 
phenyl and the phenolic hydroxyl group is in the ortho-position or 
para-position relative to the azo group. 
The dyestuffs to be used according to the invention are obtained, for 
example, when amines of the formula 
##STR4## 
are diazotised and the diazo compounds are subjected to a coupling 
reaction with corresponding phenols. 
Fibre materials which are preferably to be dyed are those made of cellulose 
triacetate and aromatic polyesters, such as, for example, polyethylene 
terephthalate and poly-1,4-cyclohexane-dimethylene terephthalate, as well 
as those made of synthetic polyamides, such as, for example, 
polycaprolactam, polyhexamethylenediamine adipate or polyaminoundecanoic 
acid. The dyestuffs can be employed in all of the dyeing processes 
customary for the said types of fibre, that is to say in the exhaustion 
process, the HT (high temperature) process and the continuous process, 
from aqueous and organic liquor.

EXAMPLE 1 
1 part of the dyestuff of the formula 
##STR5## 
which has been finely dispersed by customary processes, is fed into 2,000 
parts of water. The pH is adjusted to a value of 5 to 6 with acetic acid 
and 4 parts of ammonium sulphate and 2 parts of a commercially available 
dispersing agent based on a naphthalenesulphonic acid/formaldehyde 
condensation product are added. 100 parts of a polyester fabric based on 
polyethylene glycol terephthalate are introduced into the dye liquor thus 
obtained and dyeing is carried out for 11/2 hours at 
120.degree.-130.degree. C. After subsequent rinsing, reductive 
after-treatment with a 0.2% strength alkaline solution of sodium 
dithionite for 15 minutes at 60.degree. C., rinsing and drying, a 
reddish-tinged yellow dyeing with good fastness properties is obtained. 
EXAMPLE 2 
100 parts of a fabric made of polyethylene terephthalate fibres are 
introduced, at room temperature, into a dyebath which has been prepared 
from 1 part of the dyestuff according to Example 1 and 1,000 parts of 
tetrachloroethylene. The bath is heated to 110.degree. C. in the course of 
20 minutes with vigorous circulation of the liquor and is kept at this 
temperature for 45 minutes. The liquor is then separated off and the 
fabric is rinsed with fresh tetrachloroethylene at 40.degree. C. After 
separating off the rinsing liquor, the dyed goods are freed from adhering 
solvent by centrifuging and drying in a stream of air. A deep, 
reddish-tinged yellow dyeing with good general fastness properties is 
again obtained. 
Similar good results are obtained when the following dyestuffs are employed 
and dyeing is carried out according to one of the processes mentioned: 
##STR6##