In practical dyeing, the liquor ratio may differ between laboratory and bulk dyeing and even varies between batches of bulk dyeing. Then, the liquor ratio dependency is a key factor for attaining reproducible results.
Reactive dye is especially susceptible to liquor ratio because its affinity to cellulosic fibers is low.
It is effective to dye cellulosic fibers at a low liquor ratio, however, the lower liquor ratio is limited because it may produce unlevel dyeing, for example, in winch dyeing.
Figure 1 shows an example of the liquor ratio dependency.
| Figure 1 Liquor ratio dependency of Sumifix trichromatic dyes |
 |
As shown in Figure 1, vinylsulfone dyes are susceptible to liquor ratio because of low affinity and Sumifix Supra dyes which are designed to have higher affinity belong to the group of reactive dyes less susceptible to the liquor ratio.
The use of lesser liquor ratio dependency dyes such as Sumifix Supra or Sumifix HF dyes is recommended to avoid the trouble caused by variations in the liquor ratio.
However, a strict control of the liquor ratio is necessary to attain reproducible results even if such low dependency dyes are used.
The effect of liquor ratio on exhaustion is controlled to some extent by the change of dyeing conditions such as the amount of inorganic salt.
The liquor ratio dependency can be thought to be theoretically defined,
where
| E: |
degree of exhaustion |
|
Ws : |
weight of dye liquor |
| K: |
partition coefficient |
|
WF: |
weight of fiber |
| L: |
liquor ratio |
|
[D]s: |
dye unit concentration in the liquor |
| t: |
dyeing time |
|
[D]F: |
dye unit concentration in the fiber |
The degree of exhaustion is given by dividing the amount of dye in the fiber at t=∞ by the amount of dye in the liquor at t=0 as shown in equation (1).
The amount of dye in the fiber is equal to the amount of loss of dye in the liquor as shown in equation (2).
From equations (1) and (2), equation (2’) is given.
On the other hand, partition coefficient K is given by equation (3)
and liquor ratio is given by equation (4)
By rearranging equations (2’), (3) and (4), equation (5) is given.
Hence the degree of exhaustion E is expressed by K and L as given by equation (5).
By replacing E by the amount of fixation, the liquor ratio dependency is easily given by the value of K of individual dyes.
Practically, if the K value of individual dyes is obtained at various liquor ratio conditions, the liquor ratio dependency can be calculated by equation (5).
Correction of dyeing concentration by liquor ratio and salt(Glauber’s salt anhyd.) using correction table.
When cellulosic fiber(cotton) is dyed with reactive dye by the exhaust method, the amount of fixation of dye is influenced by the liquor ratio and amount of inorganic salt.
Sumitomo Chemicals and other dye manufacturers present a correction table which can give dyeing concentrations for the same fixation when the liquor ratio or the amount of inorganic salt varies for attaining a low liquor ratio dyeing.
An example of a correction table for executing a dyeing concentration for the variation of liquor ratio or the amount of inorganic salt is shown in Table 1.
| Table 1 An example of a correction table for dyeing concentration for the variation of the liquor ratio(LR) or the amount of Glauber’s salt anhyd. (GS). |
| (extracted from the table for Sumifix Supra Br. Red 3BF) |
| LR |
GS
(g/L) |
Dyeing
Concentration
(% o.w.f.) |
LR |
| 1:5 |
1:10 |
1:20 |
| GS (g/L) |
| 25 |
50 |
80 |
25 |
50 |
80 |
25 |
50 |
80 |
| 1:10 |
50 |
1 |
1.03 |
0.96 |
0.89 |
1.1 |
1 |
0.92 |
1.25 |
1.08 |
0.99 |
| 1.5 |
1.04 |
0.96 |
0.89 |
1.12 |
1 |
0.92 |
1.27 |
1.08 |
0.98 |
| 2 |
1.06 |
0.96 |
0.89 |
1.13 |
1 |
0.92 |
1.28 |
1.07 |
0.98 |
| 80 |
1 |
1.11 |
1.04 |
0.96 |
1.2 |
1.09 |
1 |
1.36 |
1.17 |
1.07 |
| 1.5 |
1.13 |
1.05 |
0.96 |
1.22 |
1.09 |
1 |
1.38 |
1.17 |
1.07 |
| 2 |
1.15 |
1.05 |
0.97 |
1.23 |
1.09 |
1 |
1.39 |
1.17 |
1.07 |
| 1:20 |
50 |
1 |
0.95 |
0.89 |
0.82 |
1.02 |
0.93 |
0.86 |
1.16 |
1 |
0.92 |
| 1.5 |
0.97 |
0.89 |
0.82 |
1.04 |
0.93 |
0.85 |
1.18 |
1 |
0.91 |
| 2 |
0.98 |
0.9 |
0.82 |
1.05 |
0.93 |
0.85 |
1.19 |
1 |
0.91 |
| 80 |
1 |
1.04 |
0.97 |
0.9 |
1.12 |
1.01 |
0.93 |
1.27 |
1.09 |
1 |
| 1.5 |
1.06 |
0.98 |
0.9 |
1.13 |
1.02 |
0.93 |
1.29 |
1.09 |
1 |
| 2 |
1.08 |
0.98 |
0.9 |
1.15 |
1.02 |
0.94 |
1.3 |
1.1 |
1 |
|
(Such a table is prepared for individual dyes and released as technical information.)
By using this table the dyeing concentration can easily be corrected from the dyeing conditions you are now using to a new condition of liquor ratio or amount of Glauber’s salt anhyd..
An example of correction is made using this table.
(1) In cases where all conditions are listed in the table.
| Present condition |
-> |
New condition |
| Liquor ratio |
1：20 |
Liquor ratio |
1：5 |
| Glauber' salt anhyd. |
50g/L |
Glauber' salt anhyd. |
25g/L |
| Dyeing concentration |
2.0%(o.w.f.) |
|
|
Search the present condition of LR 1:20, GS 50g/L and dyeing concentration 2%(o.w.f.) (see left side and underlined) and new condition of LR 1:5 and GS 25g/L(see upper side), you will find 0.98 at one of the intersections. This is the correction factor.
The dyeing concentration for the new condition is obtained by multiplying the value for the present condition (2%(o.w.f.)) by this correction factor.
2.0×0.98=1.96%(o.w.f.)
In the new condition, dyeing concentration of 1.96%(o.w.f.) gives the same depth on the fiber as the present dyeing condition of 2%(o.w.f.).
(2) In cases where the present condition is not listed in the table.
For example, the present condition of GS is not listed
| Present condition |
-> |
New condition |
| Liquor ratio |
1：20 |
Liquor ratio |
1：5 |
| Glauber' salt anhyd. |
60g/L |
Glauber' salt anhyd. |
25g/L |
| Dyeing concentration |
2.0%(o.w.f.) |
|
|
In this case, two correction factors for GS 50g/L and 80g/L are read and the correction factor for 60g/L is obtained by proportional allotment.
| 1：20、2.0% (o.w.f.) |
 |
1：5 |
| 50 g/L |
 |
0.98 |
| 80 g/L |
|
1.08 |
1.01 is the correction factor for GS 60g/L, and the dyeing concentration for the new condition is 2.0×1.01=2.02%(o.w.f.).
(3) In cases where the new condition is not listed in the table.
For example, the new condition of GS is not listed
| Present condition |
-> |
New condition |
| Liquor ratio |
1：20 |
Liquor ratio |
1：5 |
| Glauber' salt anhyd. |
50g/L |
Glauber' salt anhyd. |
30g/L |
| Dyeing concentration |
2.0%(o.w.f.) |
|
|
| 1：20、2.0% (o.w.f.) |
|
1：5 |
| 50 g/L |
|
0.9 |
| 25 g/L |
|
0.98 |
The calculation is made by the same method as the case (2), and 0.92 is obtained as a correction factor.
Then the new dyeing concentration for GS 30g/L is 2.0×0.92=1.84%(o.w.f.).
(4) In cases where the value of liquor ratio is not listed
The calculation is made with the same method as the case of Glauber’s salt anhyd.
(5) In cases where the value of dyeing concentration is not listed.
The calculation is made with the same method as the case of Glauber’s salt anhyd. or liquor ratio, but in general an assumption from the nearest dyeing concentration is possible.
(6) In cases where the values of liquor ratio, amount of Glauber’s salt anhyd and dyeing concentration are not listed.
The aforementioned methods should be combined.
(7) In cases of combination dyeing.
The correction factor is calculated according to the aforementioned methods (1)～(6) for individual dyes. |