Study on Dyeing Properties of Black Rice Pigment on Tussah Silk

YanMei JIA

College of Chemical Engineering and Material Science, Eastern Liaoning University, 325 Wenhua Road, Dandong, Liaoning, 118000, China

jiayanmei1967@163.com

Key words: black rice pigment, mordant, tussah silk, dyeing

Abstract. To enrich the color of natural dyes, a natural pigment was extracted from black rice and

used to dye tussah silk. The stability of the extract to mordant ions was investigated by Visible

Spectrum and the effect of the dyeing pH, dyeing temperature, dyeing time as well as mordant process

on dyeing properties(K/S value) were studied, the optimum dyeing process was obtained. The results

show that the optimized direct dyeing process is pH value 4. 5, dyeing at 90 °C for 60 min, the color

of dyed fabric various with metal ions. In comparison, the fabric post-mordant dyeing with ferrous

sulfate exhibits the higher color depth and better color fastness．

Introduction

Due to the environmental problem associated with synthetic dyes, the textile-wet processing industry

is currently being confronted with more and more inquiries on the theme of “dyeing with natural

dyes” and, therefore, the subject of natural colors has once again become the matter of topical

interest[1,2]. Many different kinds of vegetable dyes has been used in the Chinese traditional silk

fabric production during the historical period[3]. Black rice pigment is a kind of natural dyes

extracted from black rice, the chemical composition of the pigment is anthocyanin, which include

pelargonidine, anthocyanidin, peonidin, delphinidin, petunidin and malvidin[4]. There are

considerable research works that has been undertaken for the black rice pigment is used as a food

coloring[5], but there is no work on the textile dyeing with the pigment. The present study focused on

the dyeing of tussah silk with natural black rice pigment, the purpose is also to investigate the dyeing

properties of different dyeing process, and the depth of shade were evaluated in terms of K/S and

CIELAB color difference values of the dyed substrates and the optimum process of direct dyeing and

mordant methods were obtained.

Experimental

Materials and Instruments. Tussah silk( Liaoning Tussah Silk Institute), black rice, alum, ferrous

sulfate, copper sulfate, stannous, glacial acetic acid, sodium hydroxide (Tianjin No.3 Chemical

Reagent Factory)

Datacolor SF 600 color measurement and matching machine, TU-1901 UV double beams visible

spectrophotometer, SMD laboratory-dyeing machine, SW-8 soaping color fastness tester, Y571

crocking fastness tester, pHS-3C pH meter.

Extraction of the Pigment. 30 g of black rice were dissolved into 500mL distilled water(acetate

was added to distilled water to a pH of 3) at room temperature and then soaked 6-8 h and maintained

at 50°C for 60 min. A certain amount of distilled water was added to obtain 500mL dye bath after

filtering solution.

Direct Dyeing. In order to achieve an optimal dyeing temperature and time, as well as the dye bath

pH value, silk samples were dyed with the pigment at three temperatures : 50 °C, 70°C, and 90 °C,

dyeing time different from 15 min to75 min, and the pH value of the dye bath was different from 3 to

13 by adding sodium hydroxide, keeping the material to liquor ration at 1:50 (for 1 g of goods a dye

Advanced Materials Research Vols. 821-822 (2013) pp 626-629Online available since 2013/Sep/18 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.821-822.626

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bath volume of 50 mL was applied). The effect of pH value, dyeing temperature and dyeing time on

K/S values was studied and the optimum direct dyeing process was obtained.

Mordant Dyeing. In this paper , alum, ferrous sulfate, copper sulfate, stannous were used as

mordants. The metal salts were added to give a final dye bath concentration of 6g/L mordant. The

mordant processing carried out under the bath ratio of 1:30. Pre-mordant dyeing curve and

post-mordant dyeing curve shown in Figs. 1and 2, respectively.

Fig.1 The dyeing process of per-mordant of silk fabric

Fig.2 The dyeing process of post-mordant of silk fabric

Measurement of Visible Absorption Spectroscopy and Color Properties. The extract of black

rice was diluted to a certain concentration with distilled water and then tested by the TU-1901 UV

double beams visible spectrophotometer. Meanwhile, distilled water was taken as control.

Color values were evaluated by means of K/S value and The Surface Color Depth K/S value, CIE

Lab difference values (illuminantD65/10(°) observer) were obtained by Datacolor for the samples

dyed of the various mordant solutions.The soaping and the crocking fastness of the dyed samples were

measured respectively according to GB/T 3921.1-1997 and GB/T 3920-1997.

Results and Discussion

The Spectrum Analysis of the Extract. The visible spectrum of aqueous of black rice extract was

shown in Fig. 3. From Fig. 3 we can see that the colorant has one major peak , λmax at 512 nm in the

visible region , it could be known that the color of the pigment was red.

400 500 600 700-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

512

A

Wavelength( nm)

400 500 600 700

0.0

0.5

1.0

1.5

2.0

2.5

A

Wavelength(nm)

1 — extract

2 — extract+ Sn2+

3 — extract+ Fe2+

4 — extract+ Cu2+

5 — extract+ Al3+

1

5

Fig. 3 The visible spectrum of the extract Fig. 4 Effect of mordant on the color of the extract

Advanced Materials Research Vols. 821-822 627

The Effect of Mordant on the Color of Black Rice Extract. The black rice extract showed large

changes in different mordant as shown in Fig. 4. When the black rice extract were added Sn2 +

, Al3 +

,

Fe2 +

and Cu2 +

ions, the maximum absorption wavelength move to longer wavelengths(bathochromic

shift), its λmax original 512nm were moved to 546nm, 560nm, 582nm, 595nm and the color of the

solution changes from red to pink, purple, gray-blue and blue, respectively.

Optimization of the Dyeing pH Value. The influence of pH value on K/S value of the dyed silk

（dyeing at 80°C for 60min） shown in Fig.5. From Fig.5 we can see that the K/S value will increase

with the decrease of pH value, but if the pH value is too low, the loss strength of the fiber will also

increase, so pH=4.5 is the best.

Optimization of Dyeing Temperature and Time. The K/S values of the dyed silk (dye bath

pH=4.5)were shown in Fig 6. As shown in Fig. 6 , there were some differences in K/S values in

different dyeing temperature and dyeing time with the extract of black rice. Over the same time , the

K/S value increased as the temperature rose and the increasing trend for time was less. When time was

60min , K/S tended to an equilibrium value and the optimum dyeing temperature was 90 °C and

dyeing time was 60min.

2 4 6 8 10 12 140

1

2

3

4

K/S

pH value

10 20 30 40 50 60 70 80

1

2

3

4

5

K/S

Dyeing time(min)

90℃ 70℃ 50℃Fig. 5 The effect of pH on K/S value Fig.6 The effect of dyeing temperature and time on K/S value

Optimization of Mordant Process. In order to obtain an appropriate mordant method ,silk

samples carried on the mordant process with two ways : pre-mordant , and post-mordant ,and the

samples carried on soaping process after the dyeing and the mordant processes . As shown in Table 1,

the post-mordant process had the higher K/S value than pre- mordant processes . It was because that in

post-mordant process , the dyes adsorbed in fiber were easy to form one kind of insoluble complex

compound with the metallic ion and fixed immediately on the fiber . In this experiment , the

post-mordant process was optimized.

Optimization of Mordant with K/S Value and Color Fastness. Color characteristic values and

the crocking and soaping color fastnesses of the dyed silk samples were measured and shown in Table

1. As shown in Table 1, under the action of different mordant , such as alum, ferrous sulfate, copper

sulfate and stannous, the silk obtained different shade and color depth. K/S values in descending

order is: Fe2+

> Cu2+

> Sn2+

> Al3+

> direct directing, where the dyed silk mordant with Fe2+

get the best

color depth. Crock fastness and soaping fastness of the dyed silk mordanting with iron reach level 3,

while direct dyeing sample has a poor fastness, which due to the large color change after soaping. The

processing with various mordant can improve the dyeing depth and fastness. By mordant process, the

mordant agent formed coordinate linkage between dyes and fibers, complexation reaction occurred

among mordant ions, phenolic hydroxyl of dyes and amino and carboxyl raction group of silk fibers,

the structure of the complex compound were shown in Fig. 7.

628 Advances in Textile Engineering and Materials III

Table 1 Color characteristic values and color fastness for all samples

Mordant K/S

L a* b

*

c*

Crock

fast ness

Soaping

fastness

Dry Wet Fade Stain

Direct dyeing 3.517 51.17 11.01 16.35 1.53 3~4 3 1~2 4

Iron Pre-mordant 6.56 36.72 -4.17 5.33 5.33 4 3 3 4~5

Post-mordant 6.91 35.12 -4.56 5.73 5.73 4~5 4 3~4 5

Cop-

per

Pre-mordant 4.31 45.23 -4.38 12.67 12.67 4 3 2-3 4~5

Post-mordant 4.85 44.53 -5.22 12.87 12.87 4~5 3~4 2-3 5

Alum Pre-mordant 3.62 47.90 3.87 7.91 7.91 3~4 3 1~2 4~5

Post-mordant 3.73 46.29 3.83 8.21 8.21 4 3 2 4~5

Tin Pre-mordant 5.65 43.13 -0.62 0.59 0.59 3 3 2 3~4

Post-mordant 5.80 41.58 -0.52 0.63 0.63 4 3~4 2~3 4

Dyeing conditions：liquor ratio 1:50, pH= 4.5, 90°C for 60 min

M2+

O

OH

HO

OR

O

O

O

H2N

O

C

black rice pigment mordant ion silk Fig.7 The structure of complex compound of mordant, dyes and silk fiber

Conclusions

(1) Black rice pigment showed favorable dyeing performance on silk. The optimum dyeing process

was that when the ratio of liquor was 1:50, temperature was 90, time was 60min and pH value was

4.5.

( 2 ) The silk can obtain different hue and depth of color dyed by black rice pigment with different

mordants, among which ferrisulphas post-mordanting samples have the best color depth and dyeing

fastness of the soaping color fastness and crocking fastness with greed 3.

References

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[2] CAI Suying. Dyeing performance of acutissima shell natural coloring matter for wool fabrics.

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[3] WU Ruozi,LAI Yulong,OU Shijun,et al. Extraction of Natural Tea Dyes and Its Application on

Silk Fabrics. Advanced Textile Technology. 19(2011), p. 1-4

[4] Raja A S M, Thilagavathi G. Influence of enzyme and mordant treatments on the antimicrobial

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