Table 1.
Composition and identification of cotton sample
| Yarn number in warp | Yarn number in weft | Fabric composition | Interlacing | |
| 68/1 | 68/1 | - | 100%c | 5/2 |
Table 2.
Conventional dyeing recipe
| Process | % | Substances | Temperature (°C) | Time (min.) | Remarks |
|---|---|---|---|---|---|
| Dyeing | 100 | Water | 40 | ||
| 2 | Dye auxiliary | 30 | |||
| 5 | Dyestuff | 60 | |||
| 1 | Formic acid | 40 | pH: 4.0 | ||
| Drain-Washing-Horsing-Mechanical operations | |||||
Fig. 1.
Visuals of a vacuum leather production drum (pressure/vacuum tanks, vacuum pump, rotary drum/reaction medium, control panel) and schematic diagram of the experimental system
Fig. 2.
Chemical dosing unit, and the set-up between the drum and dosing unit
Table 3.
Leather dyeing recipe under vacuum
| Process | % | Substances | Temp. (°C) | Time (min.) | Remarks |
|---|---|---|---|---|---|
| Dyeing | A | Water | 40 | A1-A4 | |
| 2 | Dye auxiliary | 30 | |||
| B | Dyestuff | C | B1-B4, C1-C3 | ||
| 1 | HCOOH | 40 | pH: 4.0 | ||
| Drain-Wash-Horsing-Mechanics | |||||
Table 4.
Leather and float analyses after conventional dyeing process
| Process | Dyestuff float exhaustion (%) | Color strength on leather after dyeing (K/S) |
|---|---|---|
| Conventional dyeing process | 71.18 ± 3.28 | 12.36 ± 0.57 |
Table 5.
Leather and float analyses after dyeing processes carried out in a vacuum cabinet in dependence on water usage ratios
| Process | Float exhaustion (%) | Color strength on leather (K/S) |
|---|---|---|
| 80% water use | 92.15 ± 1.47 | 20.36 ± 1.61 |
| 50% water use | 91.45 ± 1.77 | 19.20 ± 1.13 |
| 25% water use | 90.32 ± 2.63 | 18.78 ± 2.05 |
| Free of water use (only dissolving water) | 86.56 ± 2.82 | 16.45 ± 1.16 |
Table 6.
Leather and bath analyses after dyeing processes carried out in a vacuum cabinet in dependence on dyestuff usage ratios
| Process | Float exhaustion (%) | Color strength on leather (K/S) |
|---|---|---|
| 4% dyestuff | 94.02 ± 2.42 | 15.49 ± 1.90 |
| 3.5% dyestuff | 95.25 ± 2.91 | 12.41 ± 1.29 |
| 3% dyestuff | 93.35 ± 4.30 | 11.32 ± 1.37 |
| 2.5% dyestuff | 92.86 ± 3.19 | 9.45 ± 0.76 |
Table 7.
Leather and float analyses after dyeing processes carried out in a vacuum drum in dependence on the process time
| Process | Float exhaustion (%) | Color strength on leather (K/S) |
|---|---|---|
| 45 mins | 94.05 ± 2.87 | 15.18 ± 1.52 |
| 30 mins | 92.02 ± 1.96 | 12.38 ± 2.39 |
| 15 mins | 80.11 ± 3.69 | 10.77 ± 1.10 |
Fig. 3.
Opened collagen matrix by vacuum and full dyeing of leather
Fig. 4.
Residual floats of conventional dyeing (left) and vacuum dyeing (right)
Table 8.
Results of leather dyeing with metal complex dyestuff and cotton dyeing carried out in a conventional and vacuum cabinet
| Process | Float exhaustion (%) | Color strength (K/S) |
|---|---|---|
| Conventional system (metal complex dye, leather) | 74.05 ± 4.47 | 14.81 ± 3.35 |
| Vacuum system (metal complex dye, leather) | 96.79 ± 2.24 | 15.23 ± 0.74 |
| Conventional system (hypericum dye, cotton) | 92.21 ± 1.93 | 6.91 ± 1.23 |
| Vacuum system (hypericum dye, cotton) | 98.76 ± 2.01 | 7.06 ± 1.19 |
Table 9.
Rubbing fastness values of dyed samples
| Process | Rub fastness |
|---|---|
| Conventional system (acid dye, leather) | 4/5 |
| Conventional system (metal complex dye, leather) | 4/5 |
| Conventional system (hypericum dye, cotton) | 4 |
| Vacuum system (acid dye) | 4/5 |
| Vacuum system (metal complex dye) | 4/5 |
| Vacuum system (hypericum dye, cotton) | 4 |