Research of Salt-free Dyeing of Reactive dyes on Chitosan quaternary ammonium salt Treated Bombyx Mori Silk Fabric

Wei Zhang 1, a, You-gang Cheng 2, b, Jin-jie Zhou 3, c

1 School of Textiles and Clothes, Yancheng Institute of Technology, Yancheng, 224051 China

2 Yancheng College of Textile Technology, Yancheng, 224005 China

3 JiangSu Entry-Exit Inspection and Quarantine Bureau Textile Laboratory, Nanjing, 210001 China

a gzhangwei2000@163.com, b youcom991@126.com, c 374329529@qq.com

Keywords: Bombyx Mori silk fabric; Chitosan quaternary ammonium salt; reactive dyes; salt-free

dyeing; dyeing property.

Abstract. Chitosan quaternary ammonium salt (short for HTCC) was a strong cationic

water-soluble polymer. The bombyx Mori silk fabric was treated by HTCC solution and the

salt-free reactive dyeing process and properties of modified silk fabric were investigated in this

paper. The results showed that salt-free dyeing effect of silk fabric treated with Cibacron Blue

FN-G was better when HTCC concentration was 8g/L, the processing temperature was 60℃ and the

processing time was 35min; the optimum salt-free reactive dyeing process of silk fabric treated by

HTCC was: dyeing pH was 8.0, dyeing temperature was 90℃ and dyeing time was 70 min; HTCC

had obviously promoted dyeing effect, after salt-free dyeing, the dyeing rate, the color fixing rate

and the dyeing depth of silk fabric modified by HTCC solution were all increased obviously, and

the washing fastness and rubbing fastness were both improved slightly; the smaller molecular

weight of chitosan was used to modify to HTCC, the higher dyeing rate and color fixing rate of the

treated silk fabric were obtained.

Introduction

Due to the bright color, broad chromatography, excellent performance, applicability, and low

price, reactive dyes have been preferred by many people. However, the dyeing with reactive dyes

currently requires using a large amount of inorganic salts as accelerant [1]

, so it will definitely cause

pollution to environment. With the improvement of people's awareness on environmental protection,

the salt usage in the dyeing with reactive dyes must be restricted. Quaternary ammonium salt of

chitosan (HTCC) was a kind of water-soluble polymer [2-3]

with strong cationic property synthesized

by chitosan and 2, 3- epoxy propyl trimethyl ammonium chloride. By modifying fabrics with

HTCC, the binding ability of fabrics to anionic dyes could be greatly improved. Thus the dyeing

properties of reactive dyes were enhanced when the usage of inorganic salt reduces. In this study,

silk fabrics were performed with cationic modification using a self-made HTCC solution to explore

the optimum processing condition. The optimum process of the salt-free dyeing on modified silk

fabrics was investigated. Besides, the dyeing properties of the silk fabrics conducted with salt-free

dyeing were determined. The results obtained could provide theoretical basis for the salt-free dyeing

of pure silk by reactive dyes.

Experimental

Materials. Bombyx mori silk habotai (commercially available); HTCC (self-made [4]

, synthesized

by the chitosan with molecular weight of 21,000 and deacetylation degree of 92.6%); Reactive dye

Cibacron Blue FN-G; All chemicals (citric acid, sodium hypophosphite, sodium chloride and

sodium carbonate) used for the following investigations were chemically pure. Deionized water was

used throughout the work.

Advanced Materials Research Vol. 796 (2013) pp 347-352Online available since 2013/Sep/18 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.796.347

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Treatment process of HTCC. According to bath solution ratio of 1:50, the treatment solutions with

HTCC concentration of 2~12 g/L were prepared. In these solutions, the mass ratio concentrations of

citric acid and sodium hypophosphite were all 2% (the pH value of the treatment solution was

adjusted to 6). Then silk fabrics were immersed in the solutions and oscillated for 10~50 min in the

water bath with constant temperature of 20~80℃. Then they were fetched out. After two dipping

and rolling (pick-up 80%), they were dried at 80℃ for 5 min and then baked at 160℃ for 3 min.

Finally they were rinsed, dehydrated, and dried for dyeing.

Dyeing process of silk fabric. Salt dyeing process: dyeing solution was prepared using 4% dye

(o.w.f.) and 40g/L NaCl with bath solution ratio of 1:50. Dyeing was started at 30℃. In the process

of heating up to 80℃, salt was added in the dyeing solution by three times. And the pH value of

dyeing solution was adjusted to 7.5 using sodium carbonate. Then the dyes were fixed at 80℃ for

60 min. After dyeing finishing, the solution was cooled. Then the silk fabrics were removed out, and

washed with cold water, boiled with soap solution (soap 2 g/L, sodium carbonate, 2 g/L, 95℃, 15

min, bath ratio 1:30 ), washed with water again, and dried. Salt-free dyeing process were the same

with the salt dyeing process but without salt. Washing fastness was tested according to GB/T

3921-2008 and rubbing fastness was tested by GB/T 3920-2008 in this experiment.

Test instruments. 722S spectrophotometer, SW-12 washable color fastness tester, Y571B abrasion

color fastness tester, and CE7000 computer color testing and matching instrument were used to

investigate the dyeing behaviors of silk fabrics treated by HTCC in this experiment.

Results and analysis

The effect of HTCC concentration on dyeing properties. The treatment solutions with HTCC

concentration of 2 g/L, 4 g/L, 6 g/L, 8 g/L, 10 g/L, 12 g/L were prepared respectively. The pH

values of the solutions were all adjusted to 6. Then silk fabrics were immersed in these solutions.

After oscillated for 30 min in the water bath at 60℃, modified silk fabrics were conducted with

salt-free dyeing with dye Cibacron Blue FN-G.. Finally, the dyeing properties of these fabrics before

and after dyeing were determined, as shown in Figure 1 and Table 1.

020406080100

0 2 4 6 8 10 12HTCC concentration(g/L)(%) the dyeing rate the color fixing rate

Fig. 1 The relationship between the dyeing rate, color fixing rate and HTCC concentration

Figure 1 presented the relationship between the dyeing rate and color fixing rate of silk fabric to

Cibacron Blue FN-G dye and HTCC concentration. It could be seen from Figure 1 that, when

HTCC concentration was in 0~8 g/L, the dyeing rate and color fixing rate of silk fabrics to Cibacron

Blue FN-G dye grown with the increase of HTCC concentration. This was mainly because, after

treated by HTCC, silk fabrics generated effective adsorption and crosslink [2, 5]

with HTCC

molecules under the effect of citric acid by high-temperature baking. Thus a large number of

quaternary ammonium strong cations were absorbed on the surface and inside of the silk fabrics,

whilst reactive dye Cibacron Blue FN-G was anionic dye. By the attraction of cation and anion, the

dyeing properties of fabrics were greatly improved. When HTCC concentration was greater than

8g/L, the dyeing rate and color fixing rate of silk fabrics showed no increase with the increase of

HTCC concentration. This indicated that 8 g/L was the saturation point of HTCC combining with

silk fabrics. The dyeing rate and color fixing rate at this point also achieve the optimum points [6, 7]

.

348 Silk, Protective Clothing and Eco-Textiles

Tab. 1 The relationship between the K/S value, color fastness and HTCC concentration

HTCC

concentration

（g/L）

K/S

value

washing fastness rubbing fastness

color

fading

staining dry

friction

wet

friction stained

with cotton

stained

with silk

0 13.04 4 4 4 4-5 4-5

2 14.67 4 4 4 4-5 4-5

4 17.51 4 4 4 5 4-5

6 18.23 4 4-5 4 4-5 5

8 19.47 4 4-5 4 4-5 4-5

10 19.08 4 4-5 4 5 4-5

12 19.36 4 4 4 4-5 4-5

In addition, as shown in Table 1, the effect of HTCC concentration on K/S value exhibits the

same trend with that of dyeing rate and color fixing rate, while the effects on washing fastness and

rubbing fastness were not obvious. In summary, when modification concentration of HTCC to silk

fabrics was 8 g/L, the dyeing effect of silk fabrics to Cibacron Blue FN-G dye was the best.

The effect of HTCC solution treatment time on dyeing properties. The treatment solution with

HTCC concentration of 8 g/L was prepared and the pH value of this solution was adjusted to 6.

Then silk fabrics were immersed in this solution and oscillated for 10 min, 15 min, 20 min, 25 min,

30 min, 35 min, 40 min, 45 min, 50 min in the water bath with constant temperature at 60℃

respectively. Finally, the silk fabrics treated were conducted with salt-free dyeing using dye

Cibacron Blue FN-G. The dyeing results were shown in Figure 2 and Table 2.

020406080100

10 15 20 25 30 35 40 45 50treatment time(min)(%) the dyeing rate the color fixing rate

Fig. 2 The relationship of the dyeing rate, the color fixing with treatment time

As shown in Figure 2, when the treatment time of HTCC solution to fabrics was in 10~35 min,

the dyeing rate, color fixing rate all increased with treatment time prolongs. While after 35 min, the

dyeing rate and color fixing rate almost showed no increase. This phenomenon indicated that the

combining of HTCC molecules and silk fibroin fibers achieved to saturation at the treatment time of

35 min, and dyeing rate and color fixing rate also achieved to the optimum points [7]

at this time.

Table 2 showed that the K/S value of silk fabrics exhibited a same changing trend with treatment

time, while washing fastness and rubbing fastness displayed unobvious relationships with treatment

time. In summary, when the treatment time of HTCC was 35 min, the dyeing effect of silk fabrics to

Cibacron Blue FN-G dye was best.

Tab. 2 The relationship of the K/S value and the color fastness with treatment time

treatment

time（min） K/S

value

washing fastness rubbing fastness

color

fading

staining dry

friction

wet

friction stained

with cotton

stained

with silk

10 16.23 4 4 4 4 4

15 18.29 4 4 4 4-5 4-5

20 18.96 4 4 4 4 4

25 19.26 4 4 4-5 4-5 4-5

30 19.47 4 4-5 4 4-5 4-5

35 19.75 4 4 4 4-5 4

Advanced Materials Research Vol. 796 349

40 19.57 4 4-5 4 4 4-5

45 19.60 4 4-5 4 4 4-5

50 19.75 4 4 4 4-5 4

The effect of HTCC solution treatment temperature on dyeing properties. The treatment

solution with HTCC concentration of 8 g/L was prepared. And the pH value of this solution was

adjusted to 6. Then silk fabrics were immersed in this solution and oscillated for 35 min in the water

bath with constant temperature at 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ respectively. Finally, the

modified silk fabrics were conducted with salt-free dyeing using dye Cibacron Blue FN-G. The

dyeing results were shown in Figure 3 and Table 3.

020406080100

20 30 40 50 60 70 80treatment temperature(℃)(%) the dyeing rate the color fixing rate

Fig. 3 The relationship of the dyeing rate, the color fixing with treatment temperature

According to Figure 3 and Table 3, when the treatment temperature of HTCC solution to silk

fabrics was in 20~60℃, the dyeing rate, the color fixing rate, and K/S value all increased with

temperature increasing. When temperature exceeded 60℃, the dyeing rate, color fixing rate, and

K/S value no longer grown with temperature increased. This indicated that temperature increasing

could promote the combining of HTCC molecules and silk fiber. Moreover, when temperature

raised to 60℃, HTCC molecules and silk fabric fibers were fully inter-absorbed and crosslink. And

the dyeing rate, color fixing rate and K/S value at this temperature all achieved the optimum points.

With the continuous increase of temperature, the dyeing rate, color fixing rate and K/S value no

longer increased.

Tab. 3 The relationship of the K/S value and the color fastness with treatment temperature

treatment

temperature

（min）

K/S

value

washing fastness rubbing fastness

color

fading

staining

dry

friction

wet

friction stained

with

cotton

stained

with silk

20 14.51 4 4 4 4 4

30 15.66 4 4 4 4 4

40 18.04 4 4 4 4 4

50 19.07 4 4-5 4 4-5 4

60 19.75 4 4 4 4-5 4

70 19.73 4 4 4 4 4

80 19.68 4 4-5 4 4 4-5

It was seen from Table 3 that, treatment temperature had little effect on washing fastness and rubbing fastness. To sum up, when the treatment temperature of HTCC solution to silk fabrics was 60℃, the dyeing effect of silk fabrics to Cibacron Blue FN-G dye was best. The salt-free dyeing process of the silk fabrics treated by HTCC solution. Basing on single factor test, the treatment solution with HTCC concentration of 8 g/L was prepared according to bath ratio of 1:50. In this solution, the mass ratio concentrations of citric acid and sodium hypophosphite were all 2% (the pH value of the treatment solution was adjusted to 6). Then silk fabrics were immersed in this solution and oscillated for 35 min in the water bath with constant temperature of 60℃. Then they were fetched out. After two dipping and rolling of pick-up 80%, they were pre-dried at 80℃ for 5 min and then baked at 160℃ for 3 min. Afterwards, they were rinsed,

350 Silk, Protective Clothing and Eco-Textiles

dehydrated, and dried for dyeing. Finally, three-factor and three-level test was conducted to using L9 (3

4) orthogonal table to find the optimum process condition of the salt-free dyeing of silk fabrics.

The factors and levels were shown in Table 4. The range analysis results of orthogonal test were shown in Table 5.

Tab.4 Factors and levels

level (A)dyeing

temperature(℃) (B)dyeing time(min)

(C)pH value of

dyeing solution

1 70 50 7.0

2 80 60 7.5

3 90 70 8.0

Tab.5 Orthogonal experiment and visual analysis of salt-free dyeing of silk fiber treated with HTCC

test number A B C color fixing

rate (%) K/S value

1 1 1 1 84.2 16.08

2 1 2 2 86.5 17.31

3 1 3 3 87.9 18.52

4 2 1 2 86.9 17.50

5 2 2 3 87.4 18.61

6 2 3 1 85.9 16.53

7 3 1 3 88.2 19.08

8 3 2 1 86.4 17.12

9 3 3 2 88.9 19.64

color

fixing

rate (%)

K1 258.6 259.3 256.5

T1=782.3 K2 260.2 260.3 262.3

K3 263.5 262.7 263.5

R 4.9 3.4 7.0

K/S

value

K1 51.91 52.66 49.73

T2=160.39 K2 52.64 53.04 54.45

K3 55.84 54.69 56.21

R 3.93 2.03 6.48

As shown in Table 5, the effects of dyeing solution pH value, dyeing temperature, and dyeing

time on the test indexes of color fixing rate and K/S value were decreased in order. Range analysis

suggested that the optimum process combination of salt-free dyeing on the silk fabrics treated by

HTCC solution was A3B3C3. Namely, when dyeing temperature was 90℃, dyeing time was 70 min,

dyeing solution pH value was 8.0, the salt-free dyeing of silk fabrics showed the best color fixing

rate and K/S value.

The salt-free dyeing properties of silk fabrics treated by HTCC solution. The silk fabrics

treated by HTCC solution were performed with salt-free dyeing adopting salt-free dyeing process.

Meanwhile, the silk fabrics untreated by HTCC solution were conducted with salt dyeing for

comparison. The dyeing properties comparison results were showed in Table 6.

Tab.6 Dyeing properties of silk fabrics

samples

the

dyeing

rate

（%）

the

color

fixing

rate

（%）

K/S

value

washing fastness rubbing fastness

color

fading

staining

dry

friction

wet

friction stained

with

cotton

stained

with

silk

Salt dyeing of fabrics

without treatment 64.8 55.9 15.91 4 4 4-5 4-5 4-5

Salt-free dyeing of

fabrics with HTCC

treatment

94.5 90.2 19.86 4 4 4-5 5 4-5

Advanced Materials Research Vol. 796 351

It could be known Table 6 that, comparing with the salt dyeing properties of the silk fabrics

untreated by HTCC solution, the salt-free dyeing properties of the treated silk fabrics were

significantly improved. The dyeing rate, color fixing rate, K/S value all increase significantly, but

color fastness showed little changes. This phenomenon fully showed that HTCC had obviously

promoted dyeing effect. Thus salt-free process could be utilized to the silk fabrics treated by HTCC

solution. This finding played an important role in reducing environmental pollution.

The effect of the chitosan molecular weight on salt-free dyeing properties of silk fabrics

treated by the HTCC solution. Figure 4 showed that the dyeing rate, color fixing rate and K/S

value of the silk fabrics treated by the HTCC solutions synthesized with the chitosan with different

molecule weights. The figure indicated that the smaller the chitosan molecular weight was, the

better the dyeing properties of the silk fabrics treated by synthesized HTCC solutions. This was

mainly because that the HTCC synthesized by the chitosan with smaller molecular could more

easily enter into the silk fibers. Therefore, under the effect of citric acid, HTCC and fiber were

transformed into covalent bonds by high-temperature heating. Thus the silk fabrics were provided

with strong cationic properties, while reactive dyes were anionic. The dyeing properties of silk

fabrics were greatly improved by negative and positive attraction.

020406080100

0 5 10 15 20 25 30molecular weights of chitosan(×10000)the dyeing rate(%)the color fixing rate(%)K/S value

Fig. 4 The relationship of the chitosan molecular weight with the dyeing properties of fabrics

Summary

The salt-free dyeing effect of silk fabric treated with Cibacron Blue FN-G was better when

HTCC concentration was 8g/L, the processing temperature was 60℃ and the processing time was

35min. The optimum salt-free reactive dyeing process of silk fabric treated by HTCC was: dyeing

pH was 8.0, dyeing temperature was 90℃ and dyeing time was 70 min. HTCC had obviously

promoted dyeing effect. Compared with the salt dyeing properties of the silk fabrics untreated by

HTCC solution, the salt-free dyeing properties of the treated silk fabrics were significantly

improved, the dyeing rate, color fixing rate and K/S value all increase significantly, and the washing

fastness and rubbing fastness were both improved slightly. The smaller molecular weight of

chitosan was used to modify to HTCC, the higher dyeing rate and color fixing rate of the treated

silk fabric were obtained.

References

[1] D.S. Zhang, H. LIN, F.Zhang, et al: Textile Auxiliaries, Vol. 25(2008), p. 20

[2] W. Zhang, H. LIN, Y.H Lu, et al: Dyeing and Finishing, Vol. 1(2007), p. 8

[3] F. Zhang, H. Y. Xiao, Y. X. Chen, et al: Textile Science and Technology Progress, Vol. 1(2011),

p. 5

[4] W. Zhang, B. Zhu, Y. Y. Chen : Journal of Textile Research, Vol. 10(2010), p. 71

[5] W. Zhang, Y. H. Lu, H. Lin, et al : Silk Monthly, Vol. 5(2010), p. 5

[6] W. Xiang, J. Zhou: Dyeing and Finishing, Vol. 19(2007), p. 8

[7] X. H. Gao, X. P. Jia: Silk Monthly, Vol. 48(2011), p. 5

352 Silk, Protective Clothing and Eco-Textiles

Silk, Protective Clothing and Eco-Textiles 10.4028/www.scientific.net/AMR.796 Research of Salt-Free Dyeing of Reactive Dyes on Chitosan Quaternary Ammonium Salt Treated

Bombyx mori Silk Fabric 10.4028/www.scientific.net/AMR.796.347