Pad cold-dwell process for dyeing wool piece goods with reactive dyes under acid pH

Hitherto there has been no practical pad-dwell process for wool piece goods which could be carried out without using large amounts of textile assistants. In addition, it has been necessary with all these processes to supply energy. Furthermore, large amounts of urea have always been used, which inevitably resulted in a high degree of waste water pollution. It has now been recognized according to the invention that satisfactory results can be obtained in the dyeing of wool piece goods with reactive dyes by effecting the padding operation with the dye solutions within the pH range from 1.5 to 4 and at room temperature and the subsequent dwell operation to obtain dye fixation without supply of heat. To prevent the formation of a frosting effect and to obtain deeper shades it is expediently possible also to add to the padding liquor nitrogen-containing ethoxylation products, in particular ethoxylated fatty amines, and/or alkyl polyglycol ethers.

The present invention relates to a pad cold-dwell process for dyeing piece 
goods made of wool or wool-containing fiber mixtures in an acid medium 
using reactive dyes. 
For dyeing textile sheet structures made of wool, the industry, in addition 
to more or less continuous methods, for example the pad warm-dwell method 
of German Patent DE-C2 No. 2,635,991, also knows pronounced pad-batchup 
processes of the type described in German Patent DE-C2 No. 2,635,990 for 
metal complex dyes and in German Patent DE-C2 No. 2,635,989 for reactive 
dyes. However, in all the aforementioned processes for dyeing wool piece 
goods, heat must be supplied either during the padding step or during the 
dwell step or even during both operations. For instance, in the case of 
the state of the art revealed by DE-C2 No. 2,635,989, the padding step is 
carried out at between 60.degree. C. and 80.degree. C. and the dwell 
temperature subsequently required for fixing the dye is then once more 
75.degree. to 85.degree. C. 
In addition, the padding liquors used in the dyeing techniques mentioned 
usually require, in addition to the dyes used, large amounts of 
hydrotropic substances, in particular urea. Yet the use of urea, which is 
contemplated to obtain full fixation of the reactive dyes, can lead to 
certain impairments of the wool material as a consequence of fiber damage. 
In this context, however, it must not be overlooked that in the hitherto 
disclosed dyeing processes operated on this basis the waste water is 
always polluted to a greater or lesser extent. Urea can not be removed 
again from such contaminated waste waters. As a consequence, the urea 
fertilizes the plants present in natural water courses and thereby reduces 
the total oxygen content of rivers and lakes. 
The invention explained hereinafter thus has for its object to remedy the 
abovementioned shortcomings and disadvantages in the dyeing of wool with 
reactive dyes by the pad-batchup method, in particular to reduce the 
energy consumption of the actual dyeing process still further and to cut 
the output of polluted waste waters, if possible. The present-day view is 
that every kind of energy saving and simple-to-remove waste waters are 
important. 
This object is achieved, then, according to the invention by padding the 
weblike textile material at a pH between 1.5 and 4, preferably between 2 
and 3, and at temperatures up to at most 25.degree. C., preferably in the 
neighborhood of room temperature, with an aqueous liquor which contains 
the dissolved reactive dyes and then, to fix the dyes, allowing this 
padded textile material to dwell for 18 to 36 hours in the moist state 
under the imported acid conditions and without further heat supply. 
The process outlined above has significant advantages in the energy and 
waste water balance over the state of the art. This is because it was 
found in the course of the claimed pad-dyeing technique in connection with 
dye fixation by cold dwell that by maintaining a certain pH range it is 
possible to dispense with any temperature control altogether. At the same 
time it is a deliberate decision not to use urea as a fixing assistant for 
greater depth of shade. The padding liquor thus contains only inorganic or 
organic acids and/or acid salts thereof, which ensure the setting of the 
pH range characteristic of the process and which are very simple to 
neutralize in the course of the treatment of the waste water. The 
principle of the present invention rests essentially on the presence of a 
high acid content in the padding liquors used. The new process can be 
carried out with the industrially required reliability and reproducibility 
of shade. The remarkable thing about this dyeing process if the simple and 
uncomplicated method. After a customary finishing of the dye after the 
dwell step excellent fastness properties are obtained on the wool thus 
dyed. Extremely brilliant and deep shades are the result. To set acid pH 
conditions, not only organic but also inorganic acids and salts thereof 
are possible according to the process. Examples thereof are potassium 
hydrogensulfate (bisulfate), sulfuric acid, amidosulfonic acid, formic 
acid, oxalic acid, succinic acid, tartaric acid among others. But it is 
also possible to use mixtures of such acid agents which are capable of 
realizing the specific pH in accordance with the invention. However, if 
this process is carried out with weak organic acids, such as, for example, 
acetic acid, which merely permit the setting of pH values within the range 
from 4 to about 4.8, it is found again and again that the resulting 
fastness properties are not as good as to be expected from the use of 
strong acids. For that reason it is necessary in those cases to add urea 
to the liquor as well, as already explained in DE-C2 No. 2,635,989. By 
contrast, the invention provides that, if strong organic acids which bring 
about pH values of 2 to 3 are used, the addition of urea can be dispensed 
with. It was not foreseeable in this respect that the setting of very 
specific acid conditions permits a reduction in temperature in the 
pad-batchup process for the dyeing of wool with reactive dyes. This 
reduction in the dyeing temperature is incidentally so appreciable that a 
true cold-dwell fixation is present. 
To prevent the appearance of frosting on the wool dyeings produced 
according to the invention, the aqueous padding liquor can if necessary 
also contain, in addition, nitrogen-containing ethoxylates or alkyl 
polyglycol ethers or a mixture of the two commercially available classes 
of compounds. This is because it was found according to the present 
invention that adding 5 to 25 g/l, preferably 10 to 15 g/l, of a 30 to 70% 
strength, aqueous formulation of fatty amines containing ethylene oxide 
groups, i.e. in particular of a reaction product of 1 mol of a fatty amine 
having 12 to 20 carbon atoms, preferably stearylamine, and 8 to 15 mol of 
ethylene oxide, or adding the same amount of an alkyl polyglycol ether, 
i.e. in particular of a reaction product of straight-chain or branched 
fatty alcohols having 10 to 18 carbon atoms, preferably 1 mol of 
isotridecyl alcohol, and 5 to 8 mol of ethylene oxide, to the dyeing 
liquor gives frosting-free, brilliant and deep shades. In addition to an 
increase in the brilliance owing to the absence of frosting it was also 
noticed here, surprisingly, that a distinct increase in the color strength 
occurs. 
Suitable reactive dyes for dyeing wool fibers and the wool portion of fiber 
mixtures are the organic dyes known under this generic 
term--irrespectively of the nature of their fiber-reactive group. This 
class of dyes is designated in the Colour Index, 3rd edition, 1971 and 
supplements 1975 as "C.I. Reactive Dyes", and embraces chemical compounds 
of dye character which are capable of entering a covalent bond with OH- 
and/or NH-containing fibers. These are primarily dyes which contain at 
least one group which is reactive with hydroxyl or amino groups in the 
fiber material of polyamide structure, a precursor thereof, or a 
substituent which is reactive with the abovementioned constituents of the 
fiber molecule. Suitable basic structures of the chromophoric system of 
these organic dyes are in particular those from the series of the azo, 
anthraquinone and phthalocyanic compounds, where the azo and 
phthalocyanine dyes can be not only metalfree but also metal-containing. 
The reactive groups and precursors which form such reactive groups are for 
example epoxy groups, the ethyleneimide group, the vinyl grouping in the 
vinylsulfonyl or in the acrylic acid radical, and also the 
.beta.-sulfatoethylsulfonyl group, the .beta.-chloroethylsulfonyl group or 
the .beta.-dialkylaminoethylsulfonyl group. Also suitable for this process 
are derivatives of the tetrafluorocyclobutyl series, for example of 
tetrafluorocyclobutylacrylic acid. Reactive substituents in reactive dyes 
are those substituents which are easily detachable and leave behind an 
electrophilic radical. Interesting substituents in this respect are for 
example 1 to 3 halogen atoms on the following ring systems: quinoxaline, 
triazine, pyrimidine, phthalazine, pyridazine and pyridazone. It is also 
possible to use dyes having a plurality of reactive groups of the same or 
a different kind. These reactive dyes of the previously defined kind 
frequently have more than one sulfo group (apart from the reactive 
grouping of the dye) in the molecule, which can be distributed over the 
chromophore in any desired manner, but are preferably bonded to the 
aromatic radicals thereon. 
The present invention is preferably carried out with dyes of the 
vinylsulfonyl type, with which the fiber reacts by an addition mechanism 
via the vinylsulfonyl form of the dye. Similarly suitable coloring 
substances in the claimed process are the conversion products of such 
known sulfonyl reactive dyes with, for example, methyltaurine, in which 
the reactive group is temporarily present in a masked form. 
By means of the dyeing technique of this invention it is possible to obtain 
satisfactory dyeing results not only on the customary wool fibers, i.e. 
wool fibers which have not been pretreated with an antifelting finish, but 
also on chlorinated wool materials or those which have been given a 
nonfelting or low-felting finish by applying a polyacrylic or polyimine 
resin film. 
The claimed process is in general carried out as follows: 
The wool textile to be dyed is padded at about room temperature with the 
padding liquor which contains dye, acid and possibly assistants. The wet 
pickup can be here, depending on the type of the textile material, between 
50 and 130% on weight of dry fiber. 
To obtain dye fixation, the moist material is then dwelled at about room 
temperature for 18 to 36 hours, which is customarily effected in the 
rolled-up state with slow rotation of the roller. Expediently this measure 
is effected in the substantial absence of air, which is obtained by 
wrapping the batched-up material in a plastic film. Given a suitably low 
wet pickup, the dwell process with the moist textile material can also be 
accomplished in the plaited state. Subsequently the completed dyeing is 
rinsed, washed and neutralized. 
In the worked examples below, the percentages relate to the weight of the 
objects thus designated. The reactive dyes mentioned are used in the 
commercially available form and constitution:

EXAMPLE 1 
(a) An aqueous padding liquor at about 20.degree. C., which contains 
10 g/l of a 4% strength, aqueous thickening based on galactomannan, 
15 g/l of the dye Reactive Blue 19 having the C.I. No. 61,200 and 
20 ml/l of concentrated (96% strength) sulfuric acid 
and has been brought to pH 2.8, is used to pad a fabric made of wool not 
pretreated with an antifelting finish. The wet pickup in the padding is 
100% on weight of dry fiber. The material treated in this way is then 
batched up in the moist state resulting from squeezing off the excess 
liquor and is left to dwell at room temperature for 24 hours with slow 
rotation of the batching roller to obtain dye fixation. Thereafter the 
dyeing thus produced is washed off with water. 
The result is a blue dyeing which has good to very good wet fastness 
properties, but which displays a frosting effect. 
(b) If the dyeing liquor prepared under 1(a) also has added to it 
15 g/l of a 30% strength aqueous formulation of the reaction product of 1 
mol of stearylamine with 12 mol of ethylene oxide (with added triisobutyl 
phosphate as a defoamer) and the padding step and also the dwell operation 
to obtain dye fixation are carried out in accordance with the above method 
1(a), a corresponding blue dyeing without the appearance of frosting is 
obtained. 
If the color strength of the dyeing obtained in 1(a) was then for 
comparison determined in reflectance measurements by means of a 
colorimeter of the MM 7000 type from Instrumental Color Systems and set 
equal to 100, then by means of color measurements on the same basis in the 
case of the dyeing obtained as in 1(b) the color strength could be found 
to be 125. 
(c) If, however, the dyeing liquor specified under 1(a) had added to it, 
instead of the substance as per 1(b), in this case 
15 g/l of an aqueous solution of the reaction product of 1 mol of 
isotridecyl alcohol with 5 mol of ethylene oxide, 
then dyeing and finishing in accordance with method 1(a) produced in this 
case a particularly brilliant blue dyeing without frosting, which, on the 
basis of color measurements under the conditions specified there, had in 
comparison to the dyeing as per 1(a) (color strength=100) a color strength 
of 211. 
The same dyeing results as in 1(a), 1(b) and 1(c) are obtained on using 7 
g/l of amidosulfonic acid, in place of sulfuric acid, and an otherwise 
identical composition of the padding liquor. 
EXAMPLE 2 
(a) An aqueous padding liquor of the composition specified in Example 1(a) 
except that instead of the blue dye used there it contains here 
20 g/l of the yellow reactive dye of the formula 
##STR1## 
and instead of sulfuric acid 80 g/l of potassium hydrogensulfate, is used 
to pad at room temperature and pH 2.9 a wool flannel material without a 
nonfelting finish with a wet pickup of 95% (on weight of fiber). After a 
20-hour dwell time to obtain dye fixation at 20.degree. C. the rest of the 
procedure is as described in Example 1(a). 
The result is a full yellow dyeing having very good wet fastness 
properties. 
(b) If in preparing the above yellow dyeing the dyeing liquor made up as in 
2(a) is used, however, with further addition of ethoxylated stearylamine 
as in Example 1(b), then finishing as per Example 1 gives a frosting-free 
dyeing having a color strength of 131, as determined colorimetrically 
against dyeing 2(a) (color strength=100). 
(c) If, however, dyeing liquor which is in accordance with 2(a) is used as 
described in Example 1(c), with further addition of ethoxylated 
isotridecyl alcohol, then a highly brilliant yellow dyeing having a 
colorimetrically determined strength value of 222 compared with the 
reference value of 100 from Example 2(a) is obtained. 
EXAMPLE 3 
(a) An aqueous padding liquor at about 20.degree. C., which contains 
10 g/l of a 4% strength aqueous thickening based on galactomannan, 
15 g/l of the red reactive dye of the formula 
##STR2## 
and 90 g/l of tartaric acid, 
is used to pad at pH 3 a wool fabric with a polyimine resin nonfelting 
finish with a wet pickup of 100% (on weight of fiber). After a 28-hour 
dwell time to obtain dye fixation at room temperature the rest of the 
procedure is as specified in Example 1a). 
The result is a full red dyeing. 
(b) If, however, in dyeing with the liquor of 3(a) 12 g/l of ethoxylated 
stearylamine are present as in Example 1(b), then the result is a 
brilliant red dyeing having a colorimetrically determined color strength 
of 151 compared with that of dyeing 3(a) having the reference value of 
100. 
(c) If dyeing liquor 3(a) has additionally added to it ethoxylated 
isotridecyl alcohol as in Example 1(c) and the procedure followed is as 
specified there, the result is, after finishing, a particularly brilliant 
red dye having a color strength of 164 compared with that of dyeing 
3(a)=100. 
EXAMPLE 4 
(a) An aqueous padding liquor at about 25.degree. C., which contains 
10 g/l of a 4% strength, aqueous thickening based on galactomannan, 
30 g/l of the dye Reactive Orange 16 having the C.I. No. 17,757 and 
20 ml/l of concentrated (96% strength) sulfuric acid, 
and has been brought to pH 2.5, is used to impregnate a wool fabric which 
has no nonfelting finish with a wet pick-up of 100% (on weight of fiber). 
After a batchup time of 24 hours at room temperature to obtain dye 
fixation and also finishing as described in Example 1(a) an orange-red 
dyeing having very good wet fastness properties is obtained. 
(b) If, within the framework of the above dyeing method, ethoxylated 
stearylamine as in Example 1(b) is also added, the result is a 
corresponding dyeing having a measured depth of shade of 179, compared 
with that of dyeing 4(a)=100. 
(c) On adding the ethoxylated isotridecyl alcohol quoted in Example 1(c) to 
liquor 4(a) at otherwise identical dyeing conditions a particularly 
brilliant orange dyeing of depth of shade 224, compared with that of 
dyeing 4(a)=100 is obtained. 
EXAMPLE 5 
(a) An aqueous liquor at room temperature which has the composition 
specified in Example 1(a), except that the yellow dye specified there is 
replaced here by 
30 g/l of the commercially available (with added methyltaurine) red 
reactive dye of the formula 
##STR3## 
is used to pad a wool fabric with no nonfelting finish at pH 2.5 with a 
wet pickup of 100% (on weight of fiber). After a dwell time of the moist 
material of 24 hours at about 20.degree. C., the textile material thus 
dyed is washed off with water. The result is a full red dyeing. 
(b) If in preparing the above dye the ethoxylated stearylamine of Example 
1(b) is also added the result is a deeper red dyeing than obtained in 
process 5(a), having a color strength of 126 compared with the color 
strength of 100 for dyeing 5(a). 
(c) The addition of ethoxylated isotridecyl alcohol as specified in Example 
1(c) to padding liquor 5(a) leads to a highly brilliant, deep red dyeing 
of color strength 188 compared with the dyeing of 5(a) having the 
reference value 100. 
EXAMPLE 6 
An aqueous padding liquor at room temperature, which contains 
10 g/l of fully etherified (methylated) carob bean flour, 
15 g/l of a 30% strength aqueous solution of the reaction product of 1 mol 
of stearylamine with 12 mol of ethylene oxide (with triisobutyl phosphate 
as defoamer), 
40 g/l of the red reactive dye of the formula 
##STR4## 
10 g/l of the yellow reactive dye of the formula 
##STR5## 
and 25 ml/l of concentrated sulfuric acid 
and has been brought to pH 2.6, is used to pad a wool fabric with no 
nonfelting finish with a wet pickup of 95% (on weight of fiber). After a 
24-hour dwell time to obtain dye fixation at about 20.degree. C., 
finishing is effected as described in Example 1(a). 
The result is a brilliant highly red dyeing having very good wet fastness 
properties. 
EXAMPLE 7 
An aqueous padding liquor as described in Example 6, which instead of the 
dyes specified there contains here a mixture of 15 g/l of the yellow 
reactive dye of the formula 
##STR6## 
and 15 g/l of the red reactive dye of the formula 
##STR7## 
and also 15 g/l of the dye Reactive Blue 19 having the C.I. No. 61,200 
and 
25 ml/l of concentrated sulfuric acid 
is used for dyeing and dye fixation as specified in Example 6. 
The result is a neutral gray having good to very good fastness properties.