O o d h e a d p u b L i s h I n g L i m I t e d

8.4
Reactive dyes for wool
The chemistry of reactive dyes for wool has been fully reviewed
48,49
 but the
most important features will be detailed. Studies on wool were of great
significance in the early development of reactive dyes. In particular the 
ω-
chloroacetylamino reactive group appeared as early as 1938 in the IG dye,
Supramino Orange R, as shown in 
Fig. 8.10.
Ciba put together a small range of bright wool dyes containing this grouping
in 1954 (Cibalan Brilliant). In 1952, following the patented work of Heyna
and Schumacher,
50
 Hoechst marketed Remalan and Remalan Fast, 2:1
premetallised reactive dyes for wool which contained pendant
sulphatoethylsulphone residues capable of elimination to vinylsulphone reactive
groups when applied from boiling dyebaths above pH 5. Hoechst even sold
chrome dyes with the sulphatoethylsulphone residue being incorporated in
the dye molecule, these being Metachrome Orange H3R, Metachrome Gey
RL, Salicinchrome Orange H-3R and Salicinchrome Grey RL. However, it
seemed that the marketing push for selling these dyes as fibre reactive systems
was somehow lacking, probably because wool had only a small share of the
textile fibre market. It was only when developments took place which allowed
covalent fixation of dyes on the major textile fibre, cotton, that a major
marketing effort commenced to sell the reactive dye concept for wool dyeing.
Also it should be noted that the above early reactive dyes for wool gave
considerable problems of unlevel dyeing, especially in piece dyeing and
yarn hank dyeing; thus their usage was mainly in the fields of loose-wool
stock and wool top dyeing. A major advance in reactive dyes for wool
NH
C
CH
2
Cl
Na+ –O
3
S
N
N
HO
O
8.10
 Supramino Orange R.
© 2009 Woodhead Publishing Limited

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The coloration of wool
199
occurred in 1966 with the launch of the Lanasol dyes (Ciba-Geigy); these
dyes were based on the 
α-bromoacrylamido group
51
 and were sold with the
very important level dyeing auxiliary, Albegal B. Albegal B is an amphoteric
product which possibly has the general structure shown in 
Fig. 8.11.
52
It is noteworthy that dyeing in the presence of this novel product alleviated
the problems of unlevel dyeing, associated with reactive dyeing of wool. By
happy coincidence the launch of the Lanasol dyes coincided with the marketing
of truly machine-washable wool, produced by the continuous chlorine–
Hercosett treatment of wool tops, a process developed by scientists at CSIRO
and IWS.
53
 Other companies followed suit, Bayer and Sandoz launching
difluoro-monochloro-pyrimidine dyes (Verofix/Drimalan F)
54
 and Hoechst
launching a reassembled range of ‘blocked’ vinylsulphone dyes (Hostalan).
55
Dyeings produced on the chlorine-Hercosett treated substrate with acid dyes,
acid milling dyes and premetallised dyes did not show adequate wash-fastness
properties but dyeings produced with reactive dyes gave outstanding washing
performance.
56
Modern reactive dye systems for wool fibres
In the light of increasing environmental concerns with heavy metals it is
desirable to use reactive dyes to match deep shades of black and navy blue
in order to offer the dyer a real alternative to chrome dyes. In this context
dye manufacturers have increased their efforts to offer wool dyers ranges of
attractively priced reactive dyes; examples include Lanasol CE dyes from
Ciba, Realan dyes from DyStar and Drimalan dyes from Clariant. Black and
navy blue shades are often based on the popular and widely available dye, CI
Reactive Black 5. This dye is a bifunctional reactive dye since it contains
two sulphatoethylsulphone residues, which activate to vinylsulphone on boiling
at pH 5.5.
Müller
57
 has reviewed the nature and amount of AOX residues in textile
effluents; various reactive dye systems such as halo-triazines and halo-
pyrimidines can give problems and AOX discharges can be reduced by selecting
dyes containing only sulphatoethylsulphone residues as the reactive group.
  
  
C H —
(CH CH O) SO
N
+
—(CH CH O) H
CH
C== O
NH
18
37
2
2
3
–
2
2
2
2
n
m




m + n = 7
8.11
 Amphoteric levelling agents for use in wool reactive dyeing.
© 2009 Woodhead Publishing Limited

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Advances in wool technology
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