**1.1 Wool**

298 Textile Dyeing

Zenerino, A, Darmanin, T, de Givenchy, ET, Amigoni, S, & Guittard, F. (2010}). Connector

Zhai, L, Berg, M, Cebeci, F, Kim, Y, Milwid, J, Rubner, M, & Cohen, R. (2006}). Patterned

Zhang, D, Sun, Q, & Wadsworth, LC. (1998). Mechanism of corona treatment on polyolefin films. *Polymer Engineering and Science,* 38, 6, JUN, pp. 965-970, 0032-3888. Zhu, Z., Kelley M. J. (2004). Poly(ethylene terephthalate) surface modification by deep UV

polymers. *Langmuir,* 26, 16, AUG 17, pp. 13545-13549, 0743-7463.

(172 nm) irradiation, *Applied Surface Science*, 236, pp. 416-425.

*Nano Letters,* 6, 6, JUN, pp. 1213-1217, 1530-6984.

ability to design superhydrophobic and oleophobic surfaces from conducting

superhydrophobic surfaces: Toward a synthetic mimic of the namib desert beetle.

#### **1.1.1 Treatment with metal salts**

The effect of absorption of some metal ions by wool such as copper, iron, aluminum, cobalt and nickel was thoroughly investigated. The pretreatment of wool with some di- carboxylic acids was studied to present their impact on the amount of metal uptake by wool on its dyeing properties(1-3). Wool fabric was treated with copper sulphate and ferric chloride solutions (1.5% o.w.f.) at 40° and 60° C for 30 min. The effect of starting pH value of the salt solution on the acquired uptake of copper and iron by wool is illustrated in Fig. 1.1. It can be noticed that the metal uptake increases linearly and strongly for both copper and iron in the range of pH value 3-6 and 1.5-3.5 respectively. Increasing the temperature from 40° to 60°C led to an increase in the amount of metal uptake but the rate was considered to be almost the same or slightly changed. The metal uptake by wool fibres could be enhanced by chemically modifying the fibre with chelating agents able to coordinate the metal ions. It was found that treatment of wool with tannic acid and EDTA has increased the metal uptake by wool and consequently increased the weight gain (4, 5). Wool was treated with some organic acids such as oxalic, maleic, succinic and adipic acids at 75°C for 90 min. There was a weight gain in wool accompanied to these di-carboxylic acids treatments. The % increase in weights of wool was 3.6, 3.2, 2.6 and 2.5 for wool pretreated with the aforementioned organic acids respectively. These increases in weight were found to correspond to the increase in the carboxyl content of wool from 421.7 meq/100 g fibres for untreated one to 622.1, 530.5, 457.3 and 425 meq/100 g fibres for the treated wool with the aforementioned acids respectively (6). The metal uptake of treated wool with oxalic acid increases as shown in Table 1.1. Other acids treatment did not enhance the metal uptake property. This may be due to the large molar volume of these acids which might restrict the penetration of metal ions into wool macrostructure (3).

The elongation %, tensile strength at break and alkali solubility of the untreated and treated wool with metal salts solution at 60ºC are illustrated in Table 1.2. The results indicated that nearly no changes in the mechanical properties of the treated wool were noticed. It is well known that the tensile properties of wool could be affected negatively during the dyeing process especially at high temperature (7) that might require using of protective agents. This treatment made it possible to dye wool at lower temperature and reflects more protection of wool from damage during the dyeing process (Table 1.2).

following:

treatment


 75C 85C 95C

 75C 85C 95C

Pretreatment of Proteinic and Synthetic Fibres Prior to Dyeing 301

**Dyeability:** Four steps could be envisaged in the process of dye uptake: a) diffusion into the fibre surface, b) transfer across the surface, c) diffusion within the fibre to appropriate sites and d) bonding to proper sites. Various algebraic expressions have been derived from Fick's laws of diffusion in an attempt to describe experimental dyeing rates. Near parabolic rates were seen (8). The equilibrium for the dye- wool interaction could be separated into the

H OOC W H.OOC W Probably the rate of the second step would be fast and thus the first step would be the rate determining. Combining the metal ions with carboxyl groups led to increasing the reaction

Pretreatment of wool prior to the metal treatment with some organic acids such as oxalic, maleic, succinic and adipic had enhanced the wool dyeability. Oxalic acid led to nearly complete exhaustion of dye from the dyebath after 30 min at 95ºC as compared to 90 % exhaustion for the untreated one dyed for 60 min. at the same temperature (Table 1.3). The dyeing rate constant and the diffusion coefficient increased by the aforementioned treatment while the half dyeing time decreased (Table 1.4). Both alteration (alt.) and staining (st.) washing fastness properties of wool dyed with acid dye at 95ºC were found to be good.

Type of Samples Dye uptake (g dye / 100 g fibre)

Treated wool 1.89 1.9 1.92 Pretreated wool with: oxalic acid2.0 2.0 1.96 Maleic acid 1.99 2.0 1.96 Succinic acid 1.94 - - Adipic acid 1.96 - - Treatment: 0.03 M acid/100 g fibre, 75 °C, 90 min., liq. ratio 1:50, 3 %metal salt, 60 °C, 30 min., liq ratio 1:30. Dyeing: 2% C.I. Acid Red 41, \* C. I. Acid Orange 19, 95ºC, 30 min, pH 4.5, liq. ratio 1: 50 Table 1.3. Dyeability of pretreated wool fabric with some organic acids followed by metal

Type of Sample t1/2



ye W NH . D ye OOC W

Cobalt sulphate Nickel sulphate \*Ferric Chloride

 k' x 10 -4 (cm/sec) ½

4.976 6.01 8.12

7.417 8.08 9.901

8.487 9.343 10.954 D x 10 -7 cm2 sec -1

2.7611 2.8151 3.5684

2.7914 2.9277 4.2467

3.0113 3.2365 4.5914

min

14.5 13.3 9.0

12.2 11.1 7.8

10.0 8.9 6.7

– W NH .OOC W D 3 3

in the forward direction and consequently increasing the rate of dyeing.

Fig. 1.1. Dependence of metal uptake by wool on the pH value of its solution at different temperatures. Treatment: 1.5 % (o.w.f), Δ-Δ copper sulphate, o-o ferric chloride, \_\_\_40º C, \_ \_60 ºC, 30 min, liq. ratio 1:30.


Treatment: 0.03 M acid, 75 °C, 90 min., liq. ratio 1:50, 3 % metal salt, 60 °C, 30 min., liq ratio 1:30.



Treatment: 1.5 % (o.w.f.) metal salt solution; 30 min., pH 3.5; liq. ratio 1:30.

Table 1.2. Tensile strength, elongation % at break and alkali solubility of treated wool fibre with metal salts

Fig. 1.1. Dependence of metal uptake by wool on the pH value of its solution at

\_\_\_40º C, \_ \_60 ºC, 30 min, liq. ratio 1:30.

uptake

with metal salts

different temperatures. Treatment: 1.5 % (o.w.f), Δ-Δ copper sulphate, o-o ferric chloride,

Wool Samples Metal uptake (mg/100 g wool)


%

Table 1.2. Tensile strength, elongation % at break and alkali solubility of treated wool fibre

1-Untreated wool 26 41.5 8.82 2-Treated with: Aluminum sulphate 25 45.5 8.67 Copper sulphate 20 37.5 8.23 Ferric chloride 22 43.5 8.42 Cobalt sulphate 21 41.6 8.81 Nickel sulphate 21 42.0 8.80

Type of Sample Elongation

Treatment: 1.5 % (o.w.f.) metal salt solution; 30 min., pH 3.5; liq. ratio 1:30.

Copper Cobalt Nickel

Tensile Strength

(Kg) Alkali Solubility

**Dyeability:** Four steps could be envisaged in the process of dye uptake: a) diffusion into the fibre surface, b) transfer across the surface, c) diffusion within the fibre to appropriate sites and d) bonding to proper sites. Various algebraic expressions have been derived from Fick's laws of diffusion in an attempt to describe experimental dyeing rates. Near parabolic rates were seen (8). The equilibrium for the dye- wool interaction could be separated into the following:

$$\begin{aligned} \text{W}-\text{NH}\_3^+\text{.}\text{OOC}-\text{W} + \text{Dye} &\rightleftharpoons \text{W}-\text{NH}\_3^+\text{.}\text{.}\text{Dye} + ^\text{.}\text{OOC}-\text{W} \\ \text{H}^+\text{+}^\text{-}\text{OOC}-\text{W} &\rightleftharpoons \text{H}\text{OOC}-\text{W} \end{aligned}$$

Probably the rate of the second step would be fast and thus the first step would be the rate determining. Combining the metal ions with carboxyl groups led to increasing the reaction in the forward direction and consequently increasing the rate of dyeing.

Pretreatment of wool prior to the metal treatment with some organic acids such as oxalic, maleic, succinic and adipic had enhanced the wool dyeability. Oxalic acid led to nearly complete exhaustion of dye from the dyebath after 30 min at 95ºC as compared to 90 % exhaustion for the untreated one dyed for 60 min. at the same temperature (Table 1.3). The dyeing rate constant and the diffusion coefficient increased by the aforementioned treatment while the half dyeing time decreased (Table 1.4). Both alteration (alt.) and staining (st.) washing fastness properties of wool dyed with acid dye at 95ºC were found to be good.


Treatment: 0.03 M acid/100 g fibre, 75 °C, 90 min., liq. ratio 1:50, 3 %metal salt, 60 °C, 30 min., liq ratio 1:30. Dyeing: 2% C.I. Acid Red 41, \* C. I. Acid Orange 19, 95ºC, 30 min, pH 4.5, liq. ratio 1: 50



Pretreatment of Proteinic and Synthetic Fibres Prior to Dyeing 303

Chitosan sorption on proteinic fibres is found to be due to ionic interaction between the negative charges of carboxylic groups in the polypeptide macromolecule and the protonated amino groups of chitosan, and possibly due to hydrogen bonding between the hydroxyl or amide groups of polypeptide chains and similar groups in chitosan. The application of chitosan onto wool reveals even dye uptake resulting in higher dye exhaustion with level and full penetration of dye molecules in wool fibres(16). The treatment of wool with chitosan permits the formation of an approximately uniform sheath on individual fibres. Chitosan treatment does not involve changes in colour fastness of the dyed wool to any extent, but may reveal some problems such as weak binding. Such problems are reported to be overcome upon applying chitosan onto wool with a nonionic surfactant (17, 18). The possibilities of improving the reactive dye affinity to wool fibres and their protection from damage by conducting chitosan treatments of wool before subjecting it to reactive dyeing were reported (10). Wool fabric was treated with chitosan and nonionic surfactant using diluted concentrations 0.1- 0.7 % (w/w) and then dyeing the pretreated wool with reactive dye at 80°C for 5-60 minutes. The pretreatment of wool with chitosan enhanced the colour

Fig. 1.2. SEM graph of untreated wool.

Fig. 1.3. SEM graph of sulphamic acid-treated wool.

**1.1.3 Treatment with chitosan** 


Treatment: 1.5 % (o.w.f.) metal salt solutions, 30 min, pH 4.5, \*\*pH 3.5, liq. ratio 1: 30. Dyeing: 1% (o.w.f.), \* 2% (o.w.f) C.I. Acid Blue 221, pH 4.5, liq. ratio 1: 50.

Table 1.4. Half dyeing time (t1/2), dyeing rate constant (k') and diffusion coefficient (D) of untreated and treated wool with metal salts.

#### **1.1.2 Treatment with sulphamic acid**

Chemical treatments of wool and its blends with synthetic fibres are one of the goals to provide new characteristics and to promote their dyeabilities (10, 11). The advent of a new practical dye resist treatment, based on sulphamic acid for wool dyeing has brought about renewed interest in its dyeing capabilities especially for its acrylic blend. The application of sulphamic acid onto wool revealed a promoted possibility of cationic dyeing. The dye uptake usually resulted in higher dye exhaustion with level and full penetration of dye molecules into wool fibres. Sulphamic acid treatment offered the possibility of producing deeper shade on wool/acrylic blend without increasing the dye concentration used. Dyeing of the blend could be then achieved with single class of dye and possibly in one bath (12, 13). Wool fabric was immersed in sulphamic acid solution using concentration of 5-20 % (w/w), padded to pickup 70 %, dried at 80°C for 15 min., and then thermofixed at 160°C for 5 min. The treated wool was subjected to dyeing with cationic dye at 80°C for time intervals of 5–60 min. Wool pretreated with either 15 % (o.w.f) sulphamic acid solution attained nearly the same dye uptake upon dyeing with cationic dye under the same conditions. Alkali solubility of wool before treatment was found to be 15.6 % and that of the sulphamic pretreated wool was found to be 30 %, indicating that there is some damage of wool pretreated under these conditions. Infrared spectroscopy of the untreated and pretreated wool with sulphamic acid shows that no new peak appearance except SO4 -2 groups, which appeared at 1150 – 1050 cm-1 and also a peak belonging to sulphamic acid groups appeared at 1090 cm-1 as compared with the untreated one (14, 15). SEM of the untreated and the sulphamic acid treated wool shows that most of the scales have disappeared and wool attained a relatively smoother surface than the untreated one (Figs 1.2 and 1.3).

min

9.3 8.4 7.4

8.8 8.2 6.5

12.3 11.7 8.6

11.7 10.5 8.0

 k' x 10 -4 (cm/sec) ½

17.3 18.762 20.692

18.1288 19.6198 22.3721

6.668 7.754 9.3165

7.1703 8.2731 9.7906 D x 10 -7 cm2 sec -1

3.5014 3.638 4.1716

3.6961 3.6427 4.6041

3.0978 3.2777 4.3088

3.1014 3.3779 4.5258

Type of Sample t1/2





untreated and treated wool with metal salts.

**1.1.2 Treatment with sulphamic acid** 

Treatment: 1.5 % (o.w.f.) metal salt solutions, 30 min, pH 4.5, \*\*pH 3.5, liq. ratio 1: 30.

attained a relatively smoother surface than the untreated one (Figs 1.2 and 1.3).

Table 1.4. Half dyeing time (t1/2), dyeing rate constant (k') and diffusion coefficient (D) of

Chemical treatments of wool and its blends with synthetic fibres are one of the goals to provide new characteristics and to promote their dyeabilities (10, 11). The advent of a new practical dye resist treatment, based on sulphamic acid for wool dyeing has brought about renewed interest in its dyeing capabilities especially for its acrylic blend. The application of sulphamic acid onto wool revealed a promoted possibility of cationic dyeing. The dye uptake usually resulted in higher dye exhaustion with level and full penetration of dye molecules into wool fibres. Sulphamic acid treatment offered the possibility of producing deeper shade on wool/acrylic blend without increasing the dye concentration used. Dyeing of the blend could be then achieved with single class of dye and possibly in one bath (12, 13). Wool fabric was immersed in sulphamic acid solution using concentration of 5-20 % (w/w), padded to pickup 70 %, dried at 80°C for 15 min., and then thermofixed at 160°C for 5 min. The treated wool was subjected to dyeing with cationic dye at 80°C for time intervals of 5–60 min. Wool pretreated with either 15 % (o.w.f) sulphamic acid solution attained nearly the same dye uptake upon dyeing with cationic dye under the same conditions. Alkali solubility of wool before treatment was found to be 15.6 % and that of the sulphamic pretreated wool was found to be 30 %, indicating that there is some damage of wool pretreated under these conditions. Infrared spectroscopy of the untreated and pretreated wool with sulphamic acid shows that no new peak appearance except SO4 -2 groups, which appeared at 1150 – 1050 cm-1 and also a peak belonging to sulphamic acid groups appeared at 1090 cm-1 as compared with the untreated one (14, 15). SEM of the untreated and the sulphamic acid treated wool shows that most of the scales have disappeared and wool

Dyeing: 1% (o.w.f.), \* 2% (o.w.f) C.I. Acid Blue 221, pH 4.5, liq. ratio 1: 50.

 75C 85C 95C

 75C 85C 95C

 75C 85C 95C

 75C 85C 95C

Fig. 1.2. SEM graph of untreated wool.

Fig. 1.3. SEM graph of sulphamic acid-treated wool.
