Cationic compounds, their preparation and the use thereof for the photochemical stabilisation of basic dyeable polyamide fibre materials

Cationic compounds of formula ##STR1## wherein R.sub.1 is the radical of formula ##STR2## Q is a radical of formula ##STR3## and the benzene ring W, in addition to being substituted by R.sub.1, --OH and Q, may also be substituted by C.sub.1 -C.sub.6 alkyl and C.sub.1 -C.sub.4 alkoxy, and wherein R.sub.0, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, n, Y.sub.1, Y.sub.2, Y.sub.3 and A.sup..crclbar. are as defined in claim 1, are suitable light stabilisers for photochemically stabilising basic dyeable polyamide fibre materials.

The present invention relates to novel cationic compounds, to their 
preparation and to the use thereof for the photochemical stabilisation of 
basic dyeable polyamide fibre materials, as well as to the preparation of 
the novel starting materials required for the synthesis of the final 
products. 
A substantial problem in the differential dyeing of carpets is the poor 
lightfastness of the basic dyeable polyamide component, especially the 
greening of the red component. 
It has now been found that this problem can be largely solved by dyeing the 
fibre materials with dye liquors that additionally contain novel cationic 
compounds. 
Accordingly, the present invention relates to novel cationic compounds of 
formula 
##STR4## 
wherein R.sub.1 is the radical of formula 
##STR5## 
Q is a radical of formula 
##STR6## 
and the benzene ring W, in addition to being substituted by R.sub.1, --OH 
and Q, may also be substituted by C.sub.1 -C.sub.6 alkyl and C.sub.1 
-C.sub.4 alkoxy, and wherein 
R.sub.0 is hydrogen or hydroxy, 
R.sub.2 is hydrogen, halogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 
alkoxy, C.sub.2 -C.sub.9 alkoxycarbonyl or carboxy, 
R.sub.3 is hydrogen or halogen, 
R.sub.4 and R.sub.5 are each independently of the other hydrogen, C.sub.1 
-C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy or halogen, or, when R.sub.0 is 
hydroxy and n is 1, are also the group of formula Q, 
R.sub.6 is hydrogen or C.sub.1 -C.sub.4 alkyl, and 
n is 1 or 2, 
Y.sub.1 is unsubstituted C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkyl 
which is substituted by halogen, cyano, hydroxy or C.sub.1 -C.sub.4 
alkoxy, or, together with Y.sub.2 and the linking N-atom, forms a 5- to 
7-membered heterocyclic ring, 
Y.sub.2 is unsubstituted C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkyl 
which is substituted by halogen, cyano, hydroxy or C.sub.1 -C.sub.4 
alkoxy, or, together with Y.sub.1 and the linking N-atom, forms a 5- to 
7-membered heterocyclic ring, 
Y.sub.3 is hydrogen, unsubstituted C.sub.1 -C.sub.4 alkyl or C.sub.1 
-C.sub.4 alkyl which is substituted by cyano, hydroxy, C.sub.1 -C.sub.4 
alkoxy, phenyl or C.sub.1 -C.sub.4 alkoxycarbonyl, or is C.sub.3 -C.sub.4 
alkenyl, or Y.sub.1, Y.sub.2 and Y.sub.3, together with the linking 
N-atom, form an unsubstituted or a C.sub.1 -C.sub.4 alkyl-substituted 
pyridinyl or quinolinyl radical, and 
A.sup..crclbar. is a colourless anion. 
When n is 1 and R.sub.0 is hydroxy, then the hydroxyl group is in 
2-position and the group Q is in 4-position. R.sub.0 is preferably 
hydrogen. 
A 5- to 7-membered heterocyclic ring --NY.sub.1 Y.sub.2 may suitably be a 
morpholino, piperidino, pyrrolidino or hexamethyleneimino ring 
(=hexahydro-1H-azepine). 
A 5- to 7-membered heterocyclic ring --NY.sub.1 Y.sub.2 Y.sub.3 may 
suitably be a pyridino, picolino, preferably .alpha.-picolino, or 
quinolino ring. 
Y.sub.1, Y.sub.2 and Y.sub.3 are preferably unsubstituted or 
hydroxy-substituted C.sub.1 -C.sub.4 alkyl. 
Particularly interesting compounds are those of formula 
##STR7## 
wherein R.sub.4 and R.sub.5 are hydrogen or C.sub.1 -C.sub.4 alkyl, Q and 
n are as defined for formula (1), and W.sub.1 is C.sub.1 -C.sub.4 alkoxy, 
preferably methoxy. 
Very particularly interesting compounds are those of formula 
##STR8## 
wherein Y.sub.1 and Y.sub.2 are each independently of the other methyl, 
ethyl or hydroxyethyl, and Y.sub.3 is hydrogen, methyl or ethyl, or 
wherein Y.sub.1 and Y.sub.2, together with the linking nitrogen atom, are 
the morpholino radical, and Y.sub.3 is hydrogen or methyl, or wherein 
Y.sub.1, Y.sub.2 and Y.sub.3, together with the linking nitrogen atom, are 
pyridinyl, methyl-substituted pyridinyl, preferably .alpha.-picolinyl or 
quinolinyl, and A.sup..crclbar. is Cl.sup..crclbar., CH.sub.3 
SO.sub.4.sup..crclbar. or CH.sub.3 CO.sub.2.sup..crclbar.. 
Other compounds of special interest are those of formula 
##STR9## 
wherein Y.sub.1 and Y.sub.2 are each independently of the other methyl, 
ethyl or hydroxyethyl, and 
Y.sub.3 is hydrogen, methyl or ethyl, or wherein Y.sub.1 and Y.sub.2, 
together with the linking nitrogen atom, are the morpholino radical, and 
Y.sub.3 is hydrogen or methyl, or wherein Y.sub.1, Y.sub.2 and Y.sub.3, 
together with the linking nitrogen atom, are pyridinyl, methyl-substituted 
pyridinyl, preferably .alpha.-picolinyl or quinolinyl, R.sub.3 is hydrogen 
or chloro, A.sup..crclbar. is Cl.sup..crclbar., CH.sub.3 
SO.sub.4.sup..crclbar. or CH.sub.3 CO.sub.2.sup..crclbar., and the benzene 
ring W is substituted by one or two C.sub.1 -C.sub.4 alkyl groups, 
preferably methyl and tert-butyl. 
The substituents in the above formulae have the following meanings: 
Halogen is fluoro, bromo and, preferably, chloro. 
C.sub.1 -C.sub.4 Alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, 
isobutyl, sec-butyl or tert-butyl. 
C.sub.1 -C.sub.4 Alkoxy is methoxy, ethoxy, n-propoxy, isopropoxy, 
n-butoxy, isobutoxy, sec-butoxy or tert-butoxy. 
C.sub.2 -C.sub.9 Alkoxycarbonyl is methoxycarbonyl, ethoxycarbonyl, 
n-propoxycarbonyl, n-butoxycarbonyl, pentoxycarbonyl, hexyloxycarbonyl, 
heptoxycarbonyl or octyloxycarbonyl. 
The novel cationic compounds of formula (1) are prepared as follows: 
a) to prepare compounds of formula (1), wherein Y.sub.1, Y.sub.2 and 
Y.sub.3 are an unsubstituted or a C.sub.1 -C.sub.4 alkyl-substituted 
pyridinyl or quinolinyl radical, 1 molar equivalent of a compound of 
formula 
##STR10## 
wherein R.sub.1 and W are as defined for formula (1), is reacted with at 
least 1 molar equivalent of a compound that introduces the radical of 
formula 
EQU --CH.sub.2 --N(R.sub.6)--CO--CH.sub.2 --B (9) 
wherein 
B is a leaving group such as chloro, and R.sub.6 is as defined for formula 
(4), and subsequently the resultant compound of formula 
##STR11## 
wherein R.sub.1, R.sub.6, B and W have the given meanings, is reacted with 
a compound that introduces the radical of formula 
##STR12## 
wherein Y.sub.1, Y.sub.2 and Y.sub.3, together with the linking nitrogen 
atom, are an unsubstituted or a C.sub.1 -C.sub.4 alkyl-substituted 
pyridino or quinolino ring; or 
b) to prepare compounds of formula (1), wherein Y.sub.1, Y.sub.2 and 
Y.sub.3 have a meaning that does not fall within process step a), 1 molar 
equivalent of a compound of formula 
##STR13## 
wherein R.sub.1 and W are as defined for formula (1), and Q.sub.1 is the 
radical of formula 
##STR14## 
wherein R.sub.6, Y.sub.1 and Y.sub.2 are as defined for formula (4), is 
quaternated or protonated with at least 1 molar equivalent of a compound 
of formula 
EQU Y.sub.3 --A (14), 
wherein Y.sub.3 and A are as defined for formula (4), in the temperature 
range from 0.degree. to 180.degree. C. 
The quaternisation or protonation is conveniently carded out in the 
temperature range from 30.degree. to 140.degree. C. 
Suitable quaternising or protonating agents Y.sub.3 --A are typically: 
alkyl halides, including methyl iodide, ethyl iodide, ethyl bromide, butyl 
bromide or benzyl chloride; dialkyl sulfates such as dimethyl or diethyl 
sulfate; sulfonates such as methyl or ethyl tosylate or methyl or ethyl 
benzenesulfonate; alkylene oxides such as ethylene or propylene oxide or 
epichlorohydrin; acrylates such as methyl, ethyl or butyl acrylate, 
acrylonitrile; the compounds of formula 
##STR15## 
wherein Z is methyl, ethyl, propyl, butyl or phenyl; phosphites or 
phosphonates of formula 
##STR16## 
wherein R.sub.3 " is alkyl of 1 to 4 carbon atoms, D.sub.2 is hydrogen or 
unsubstituted alkyl or alkyl which is substituted by hydroxy, cyano, 
alkylcarbonyloxy or alkoxycarbonyl, each containing 1 to 4 carbon atoms in 
the alkyl moiety, and D.sub.3 is alkyl of 1 to 4 carbon atoms. 
The quaternisation of the compounds of formula (12) with alkyl halides, 
dialkyl sulfates or sulfonates to the compounds of formula (1) is 
conveniently carried out in a solvent that is inert to the alkylating 
agent. Typical examples of suitable solvents are hydrocarbons such as 
benzene, toluene and xylene; halogenated aliphatic or aromatic 
hydrocarbons, including chloroform, ethylene chloride, chlorobenzene and 
dichlorobenzene; alcohols, including ethanol, butanol, ethylene glycol and 
ethylene glycol monomethyl ether; ethers such as ethylene glycol 
dimethylether and dioxane; or amides such as dimethyl formamide and 
N-methylpyrrolidone. 
The quaternisation with the cited alkylating agents is conveniently carded 
out in the temperature range from 0.degree. to 180.degree. C., preferably 
from 30.degree. to 140.degree. C. 
The quaternisation of the compounds of formula (12) to the compounds of 
formula (1) with alkylene oxides, epichlorohydrin and derivatives thereof 
of formula 
##STR17## 
in which Z has the given meanings, acrylates or acrylonitrile, is carded 
out in the stated temperature ranges in acidic medium, conveniently in the 
presence of an organic acid such as formic acid, acetic acid, propionic 
acid or benzoic acid. It is, however, also possible to use inorganic acids 
such as sulfuric acid, phosphoric acid or hydrohalic acids for the 
quaternisation. These inorganic acids can be used in concentrated 
commercially available form, as dilute solutions or in admixture with the 
cited organic solvents, with or without the addition of water. When 
carrying out the reaction in the presence of an organic acid, the 
concentrated form of this acid will normally be used, by itself or in 
admixture with the cited organic solvents. 
Illustrative examples of preferred phosphites and phosphonates are dimethyl 
phosphite, diethyl phosphite, dimethyl methanephosphonate, diethyl 
methanephosphonate, methyl ethylmethanephosphonate, methyl 
propylmethanephosphonate, methyl butylmethanephosphonate, methyl 
hexylmethanephosphonate, methyl octylmethanephosphonate, methyl 
decylmethanephosphonate, methyl dodecylmethanephosphate, dimethyl 
.beta.-hydroxyethanephosphonate, dimethyl .beta.-acetoxyethanephosphonate, 
dimethyl .beta.-methoxycarbonylethanephosphonate and dimethyl 
.beta.-cyanoethanephosphonate. 
The reaction is carded out in water and/or an organic solvent such as 
methanol, ethanol, propanol, isopropanol, butanol, glycol, glycol methyl 
ether, glycol dimethyl ether, glycol butyl ether, diglycol methyl ether, 
methyl ethyl ketone, methyl butyl ketone, dimethyl formamide, sulfolane, 
oxypropionitrile, toluene, xylene, benzyl alcohol, phenoxyethanol, 
benzyloxypropionitrile, in the preferred temperature range from 60.degree. 
to 190.degree. C. When using liquid phosphites or phosphonates, the 
reaction can also be carded out in the absence of an additional solvent. 
If it is desired to obtain protonated compounds of formula (1), i.e. acid 
addition salts thereof, then it is preferred to use mineral acids as 
protonating agents. Suitable protonating agents are quite generally all 
strong to medium strong organic acids or mineral acids. 
Suitable solvents in which the protonation can be carded out are ordinarily 
all inert solvents. Preferred solvents are those in which the starting 
material dissolves and from which the final product precipitates 
immediately. Illustrative examples of such solvents are: aromatic 
hydrocarbons such as benzene, toluene and xylene; halogenated 
hydrocarbons, including trichloroethane, tetrachloroethylene, 
chlorobenzene or dichlorobenzene; and also nitro compounds such as 
nitromethane, nitropropane, nitrobenzene; alkanols and open-chain or 
cyclic ethers such as butanol, dibutyl ether, ethylene glycol, ethylene 
glycol monomethyl ether, ethylene glycol monoethyl ether, anisole or 
dioxane; ketones such as cyclohexanone or methyl ethyl ketone; fatty acid 
amides such as dimethyl formamide or dimethyl acetamide; sulfoxides such 
as dimethyl sulfoxide; and carboxylates such as ethyl acetate or butyl 
acetate. 
The compounds of formula (8) are known and can be prepared by methods 
anologous to those for obtaining known compounds. 
The compounds that introduce the radical of formula (9) are likewise known 
and can be prepared by methods anologous to those for obtaining known 
compounds. A typical example of a compound of formula (9) is 
N-hydroxymethylchloroacetamide. 
The compounds of formula (10) are novel and constitute a further object of 
the invention. 
The compounds of formula (11) are known. Typical examples are: pyridine, 
picoline, preferably .alpha.-picoline, and quinoline. 
The compounds of formula (12) are also novel and therefore constitute a 
further object of the invention. 
The compounds of formula (12) can be prepared by reacting a compound of 
formula 
##STR18## 
wherein R.sub.1 and W have the given meanings, with a compound of formula 
EQU Hal--CH.sub.2 --N(R.sub.6)--CO--CH.sub.2 --N(Y.sub.1)Y.sub.2 ( 16), 
wherein Hal is chloro or bromo, and R.sub.6, Y.sub.1 and Y.sub.2 are as 
defined for formula (4), in the presence of a base, preferably sodium or 
potassium hydroxide. 
The compounds of formulae (15) and (16) are known and can be prepared by 
methods anologous to those for obtaining known compounds. 
The reaction is carded out in the temperature range from 60.degree. to 
120.degree. C., preferably from 30.degree. to 60.degree. C. 
The compounds of formula (12) can, however, also be prepared by reacting a 
compound of formula 
##STR19## 
wherein R.sub.1 and W have the given meanings, 
a) with a compound of formula 
EQU HO--CH.sub.2 --N(R.sub.6)--CO--CH.sub.2 --B (18), 
wherein B is a leaving group, preferably chloro or bromo, and R.sub.6 is as 
defined for formula (4), and 
b) reacting the resulting compound of formula 
##STR20## 
wherein R.sub.1, R.sub.6, W and B are as defined above, with a secondary 
or tertiary amine of formula 
##STR21## 
wherein Y.sub.1, Y.sub.2 and Y.sub.3 are as defined for formula (4). 
The compounds of formulae (17), (18), (19) and (20) are known and can be 
prepared by methods anologous to those for obtaining known compounds. 
The first step a) is carded out in the temperature range from 60.degree. to 
120.degree. C., and the second step b) in the temperature range from 
20.degree. to 180.degree. C. 
Accordingly, the invention also relates to the processes for the 
preparation of compounds of formulae (10) and (12). 
The cationic light stabilisers of this invention are used for dyeing basic 
dyeable (acid-modified) polyamide fibre materials in order to stabilise 
the dyed fabrics against photochemical decomposition and to enhance the 
lightfastness of the dyeings. 
The fibre materials which can be dyed in the presence of the novel light 
stabilisers are planar and, in particular, are floor coverings such as 
carpets. In addition to the above mentioned acid-modified fibre materials, 
they can consist of mixtures of unmodified (basic) and acid-modified 
polyamide materials. These materials are also known as differential dyeing 
polyamides and are described, inter alia, in W. Loy, Chemiefaserstoffe, 
Schiele und Schon, Berlin, 1978, pp. 132-141. 
The invention thus also relates to a process for stabilising basic dye able 
polyamide fibre materials. The process comprises treating said fibre 
materials with a dye liquor which, in addition to containing a disperse 
dye or cationic dye, further contains a compound of formula (1). 
The cationic dyes suitable for the process of this invention may belong to 
different dyestuff classes. They are preferably the customary salts, 
typically chlorides, sulfates or metal halides such as zinc chloride 
double salts of cationic dyes which may derive their cationic character 
from a carbonium, oxonium, sulfonium or, preferably, ammonium group. 
Illustrative examples of such chromophoric systems are azo dyes, 
especially monoazo or hydrazone dyes, diphenylmethane dyes, 
triphenylmethane dyes, methine or azomethine dyes, coumarin, ketoimine, 
cyanine, azine, xanthene, oxazine or thiazine dyes. Finally, it is also 
possible to use dye salts of the anthraquinone series containing an 
external onium group, typically an alkylammonium or cycloammonium group, 
as well as benzo,1-2-pyran dye salts that contain the cycloammonium 
group.The eligible disperse dyes, which are only very sparingly soluble in 
water and are substantially present in the dye liquor in the form of a 
fine dispersion, may belong to a very wide range of dyestuff classes, 
typically to the acridone, azo, anthraquinone, coumarin, methine, 
perinone, naphthoquinone, quinophthalone, styryl or nitro dyes. 
Mixtures of cationic or disperse dyes may also be used in the process of 
this invention. 
The invention further relates to a process for stabilising mixtures of acid 
and basic dyeable polyamide fibre materials. This process comprises 
treating said fibre materials with a liquor which, in addition to 
containing a cationic dye and a compound of formula (1), further contains 
an acid dye. 
The acid dyes are typically salts of metal-free monoazo, disazo or polyazo 
dyes, including formazan dyes, as well as anthraquinone, xanthene, nitro, 
triphenylmethane and naphthoquinone-imine dyes. The acidic character of 
these dyes is determined by acid salt-forming substituents such as 
carboxylic acid groups, sulfuric acid groups and phosphonate groups, 
phosphonic acid groups or sulfonic acid groups. These dyes may also 
contain in the molecule reactive groupings that form a covalent bond with 
the material to be dyed. Acid dyes that contain a single sulfonic acid 
group are preferred. 
Mixtures of these acid dyes may also be used, conveniently mixtures of at 
least two or three acid dyes. 
The dyeing temperature is not lower than 70.degree. C. and will usually be 
not higher than 106.degree. C. The preferred temperature range is from 
80.degree. to 130.degree. C. 
The amount of dye will depend on the desired depth of shade. Usually 
amounts of 0.001 to 10 percent by weight, preferably from 0.01 to 5 
percent by weight, based on the fibre material, have been found suitable. 
Suitable fibre material is synthetic acid-modified polyamide, by itself or 
also in blends. Synthetic acid-modified polyamide is typically that 
obtained from adipic acid and hexamethylenediamine (polyamide 66), 
.epsilon.-caprolactam (polyamide 6), from .omega.-aminoundecanoic acid 
(polyamide 11), from .omega.-aminoenanthic acid (polyamide 7), from 
.omega.-aminopelargonic acid (polyamide 8) or from sebacic acid and 
hexamethylenediamine (polyamide 610) which has been modified with 
carboxylic acids or sulfocarboxylic acids. 
The liquors suitable for use in the practice of this invention conveniently 
contain mineral acids, typically sulfuric acid or phosphoric acid, or 
organic acids such as formic acid, acetic acid, oxalic acid or, 
preferably, citric acid. They may also contain salts such as ammonium 
acetate, ammonium sulfate or sodium acetate. The acids are added in 
particular to adjust the pH of the formulations or liquors. The pH is 
usually in the range from 3 to 7, preferably from 3.5 to 4.5. 
In addition to the light stabilisers, the dyes or fluorescent whitening 
agents, the concurrent use of other assistants conventionally employed in 
dyeing technology is also possible, including typically dispersants, 
levelling agents, electrolytes, wetting agents, antifoams, foam inhibitors 
or thickeners. 
The liquors eligible for use in the practice of this invention may further 
contain photochemically active antioxidants such as copper complexes of 
bisazomethines. These copper complexes are disclosed, inter alia, in U.S. 
Pat. No. 4,655,783. 
The invention is illustrated by the following Examples in which parts and 
percentages are by weight.

EXAMPLE 1 
##STR22## 
135 g of the compound of formula 
##STR23## 
and 116 g of N-hydroxymethylchloroacetamide are homogenised and then 
added, with stirring, over 90 minutes at 0.degree.-5.degree. C. to 660 ml 
of sulfuric acid (95-97%). The reaction is allowed to go to completion for 
2 hours at 0.degree.-5.degree.. The viscous, yellow solution is then 
poured over 20 minutes into 3000 g of a mixture of ice/water of 
0.degree.-5.degree.. The resultant pale yellow suspension is stirred for 
30 minutes, filtered, and the filter product is washed with water until 
neutral and then dried, giving 191 g (96.5% of theory) of the compound of 
formula 
##STR24## 
16.5 g of the compound of formula (101b) are heated to reflux in 85 ml of 
pyridine, whereupon the dense, white suspension goes into solution. After 
3 minutes, crystals of the product precipitates. The suspension is stirred 
for 10 minutes, filtered, and the filter product is washed with toluene. 
The residue is dried at 90.degree. C., giving 19.0 g (93% of theory) of 
the compound of formula (101). 
The procedure described in this Example is repeated, but replacing pyridine 
with an equimolar amount of methyl pyridine, trimethylamine, diethyl 
methylamine, dimethyl .beta.-hydroxyethylamine, morpholine, diethyl amine, 
dimethyl amine or quinoline, and using as compound of formula (101a) an 
equimolar amount of the compound of formula 
##STR25## 
to give the compounds listed in the following Table. These compounds can 
also be prepared by reacting the compound of formula (101b) with a 
corresponding amine, and subsequently quaternising or protonating as 
described above. 
TABLE 1 
__________________________________________________________________________ 
Example 
Compound of formula 
__________________________________________________________________________ 
##STR26## 
3 
##STR27## 
4 
##STR28## 
5 
##STR29## 
6 
##STR30## 
7 
##STR31## 
8 
##STR32## 
9 
##STR33## 
10 
##STR34## 
11 
##STR35## 
12 
##STR36## 
13 
##STR37## 
14 
##STR38## 
15 
##STR39## 
16 
##STR40## 
17 
##STR41## 
18 
##STR42## 
__________________________________________________________________________ 
EXAMPLE 19 
Four 10 g hanks of basic-modified polyamide (DUPONT 554F) are each treated 
in a dyeing machine (AHIBA.RTM. dyeing machine) with liquors (liquor to 
goods ratio 1:50) that have been adjusted to pH 4.5 with acetic acid and 
which contain the following dyes and ingredients (based on the fibre 
material): red-dyeing mixture comprising: 
9 parts of the dye of formula 
##STR43## 
36 parts of the dye of formula 
##STR44## 
and 1% of a non-ionic levelling agent. 
The first dye liquor (A) contains 0.25% of the above dye mixture. The 
second dye liquor (B) contains 0.25% of the above dye mixture and 0.5% of 
compound (101) according to Example 1. 
The third dye liquor (C) contains 0.25% of the above dye mixture and 1% of 
compound (101) according to Example 1. 
The fourth dye liquor (D) contains 0.25% of the above dye mixture and 2% of 
compound (101) according to Example 1. 
The material to be dyed is put into each liquor of 40.degree. C. prepared 
as described above, treated for 5 minutes, and the temperature is raised 
to 95.degree. C. at a rate of 1.5.degree. C./minute. Dyeing is carded out 
for 30 minutes at this temperature, then 1% of acetic acid (80%), diluted 
with water, is added, and dyeing is continued for a further 30 minutes. 
The liquor is then cooled and the dyeing is rinsed in cold water, 
centrifuged and dried at 80.degree. C. 
The lightfastness of the dyeings is thereafter determined by the xenon 
light method (Swiss Standard SN-ISO 105-B02; evaluation according to the 
blue scale from 1 to 8). 
The results are summarised in the following Table I. 
TABLE I 
______________________________________ 
Lightfastness 
Liquor xenon light 300 h 
______________________________________ 
A -4 
B 5 
C 5+ 
D 5-6 
______________________________________