Advanced Materials Research Vol. 441 (2012) pp 708-712 Online available since 2012/Jan/03 at www.scientific.net © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.441.708
Establishment of Database of Color Matching System for Supercritical CO2 Dyeing Gang HUANGa, Fengchun DONGb, Junhua WANGc and Yongtang JIAd Department of Textile and Clothing, Wuyi University, Guangdong 529020, China a
[email protected],
[email protected],
[email protected],
[email protected](corresponding author)
Keywords: Supercritical dyeing; Disperse dye; Color matching; Database
Abstract. Database of color matching system for supercritical CO2 dyeing was established and its accuracy was verified. The K/S value curves of each of the trichromatic disperse dyes (C.I. Disperse Orange 30, C.I. Disperse Red 167 and C.I. Disperse Blue 79) were parallel, which indicated that the samples suits for building database of color matching system. The color matching system was emended with calibration coefficients that were derived from data of several samples dyed with a mixtures of disperse dyes in supercritical CO2. The recipes for a given sample could be found with the calibrated color matching system in supercritical CO2 dyeing. Introduction Supercritical CO2 (SC-CO2) dyeing is a cleaner and cost-effective technology for the textile industry [1]. Considerable efforts have been extended over last two decades to optimize/improve the supercritical CO2 dyeing of PET fiber, but most of research work dealt only with single dye. However, dye mixtures are frequently used in order to obtain a variety of shades to meet the customer’s requirement. Establishment of database of color matching system is useful for the dyeing of PET fibers with mixed dyes in supercritical CO2 [2]. It is not clear if the color matching system established in aqueous dyeing suits the supercritical dyeing. C.I. Disperse Orange 30 (O-30), Red 167 (R-167) and Blue 79 (B-79) were recommended by Clariant and many other dye companies as a trichromatic color system for PET dyeing in water. Database of color matching system for supercritical CO2 dyeing based on the aforementioned disperse dyes were established and its accuracy was verified in this work. Experimental Materials. PET fabric (60 g/m2, plain weave) pretreated by scouring and heat-setting, was obtained from Wujiang Co., China. Disperse dyes were purchased from Jihua Co. (China), purified by recrystallization with acetone before use. CO2 (99.99% purity) was supplied by Huaan Co. (China). Dyeing Procedure. The dyeing was performed with single dye (O-30, R-167 and B-79), a binary combination (O-30 and B-79, mass ratio 1:1) and a ternary combination (O-30, R-167 and B-79, mass ratio 1:1:1). The dye mixtures were prepared by dissolving the selected dyes in acetone with the mentioned ratio. After solvent was evaporated, the residue was dried and ground carefully. Dyeing in SC-CO2. A SC-CO2 dyeing pilot plant was designed and constructed, which comprised mainly dyeing autoclave (24.0 L), dyestuff autoclave (1.0 L), pressurized pump, circulation pump, heat exchangers and dye separator, etc. A simplified scheme of the pilot plant is shown in Fig. 1. PET fabric (ca.40 g) was wrapped on a perforated roll in dyeing autoclave, and calculated quantity of dye was added to dyestuff autoclave. After sealing dyeing autoclave, liquid CO2 was charged into the whole system by a pressurization pump and heated. When the system reached the desired pressure (25 MPa) and temperature (120 °C), valves 5 and 6 were opened, and valves 1 and 7 were closed, then the circulation pump began to operate. After dyeing for an appropriate time, valves 5 and 6 were closed, valve 7 was opened, and the dyeing autoclave was cooled down. When the temperature dropped below the glass-transition temperature of PET fiber, valve 1 was opened to let fresh CO2 into the dyeing autoclave for the extraction of unfixed dye. After the dyeing procedure was completed, the loaded CO2 was discharged and recollected. After the interior pressure of the whole system was released to atmosphere pressure, the dyed samples were taken out.
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Fig. 1 Schematic diagram of the pilot plant Determination of K/S value. The K/S value and CIELAB coordinates (L*, a* and b*) of samples were measured with a spectrophotometer (Color-Eye 7000A, Gretag Macbeth, USA) under the conditions of standard illuminant D65 and 10° observer. The reflectance at the wavelength of maximum absorption (λmax) was used to calculate the K/S value of dyed fabrics by the Kubelka-Munk Eq. 1: (1 − R) 2 K /S = . (1) 2R where K is the absorption coefficient of the substrate, S is the scattering coefficient of the substrate and R is the reflectance of the dyed fabric at λmax. Results and Discussion Establishment of Database of the Trichromatic Disperse Dyes. The K/S curves of each single dye of the trichromatic disperse dyes at different dye concentrations in SC-CO2 are shown in Fig. 2 to Fig. 4. It can be seen that K/S curves of each dye were parallel. The higher the dye concentration, the higher the K/S value. The K/S value did not increase linearly with the dye concentration. In all the three figures, no line intersected with each other, which indicated that the data obtained from the samples can be used to build the database of the color matching system. Tests of the Established Color Matching System. To verify the accuracy of the established database, several samples were dyed with mixed disperse dyes in supercritical CO2 and these samples were used as the standard samples. The theoretical recipes of the samples were obtained by using the established database of the color matching system. Both the theoretical recipes and the practical recipes of the samples are listed in Table 1. It can be seen that the theoretical recipes of each sample did not agree well with the practical recipes. This may be due to the fact that the theoretical recipe was only calculated according to the samples dyed with single dyes, ignoring interaction and competition of the mixed dyes during the dyeing process. It was reported that disperse dyes interacted and competed with each other during the supercritical dyeing process [4]. Therefore, the established color matching system should be revised. Calibration of the Established Color Matching System. Some approaches were recommended to revise the already known color matching system, one of which was to add a calibration coefficient for each single dye. The calibration coefficient was calculated by Eq. 2 [5]: Cc =
cΤ . cP
(2)
where Cc is calibration coefficient, cT theoretical dye concentration, cP practical dye concentration.
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According to Eq. 2 the calibration coefficients of each disperse dye at different concentrations are shown in Table 2 and Fig. 5. To expend the calibration coefficients to the whole x-axis, an allometric curve was employed to fit the calibration coefficients of each dye and fit equations are shown in Fig. 5. 15
14
14
(% owf) 2.00 1.50 1.00 0.75 0.50 0.25 0.15
10
K/S
8 6
(% owf) 2.00 1.50 1.00 0.75 0.50 0.25 0.15
13 12 11 10 9
K/S
12
8 7 6 5
4
4 3
2
2 0 400
1 450
500
550
600
650
0 400
700
450
500
Fig. 2 K/S value curves of C.I. Disperse Orange 30 at different dye concentration 14
10
K/S
9 8 7 6 5 4
1.0 2
y=0.6703x(-0.5070) , R =0.9460
0.8 0.6 0.4
2
y=0.4456x(-0.4112) , R =0.9667
3
0.2
2
y=0.1023x
1
0.0 0.0
0 400
450
500
550
700
O-30 R-167 B-79
1.2 Calibration coefficient
11
650
1.4
2.00 1.50 1.00 0.75 0.50 0.25 0.15
12
600
Fig. 3 K/S value curves of C.I. Disperse Red 167 at different dye concentration
( % owf)
13
550
λ/nm
λ/nm
600
650
700
0.2
λ/nm
0.4
0.6
0.8
1.0
1.2
1.4
(-0.9979)
1.6
2
,R =0.9970
1.8
2.0
2.2
%owf
Fig. 4 K/S value curves of C.I. Disperse Blue 79 at different dye concentration
Fig. 5 Allometric fit curves of calibration coefficients
The calibrated theoretical recipe for a given sample, i.e., the practical recipe in a real dyeing process, could be calculated as follows. Theoretical recipe of the given sample can be obtained according to the established color matching system. Then, the obtained theoretical recipe and the equations derived from Fig. 5 were substituted to Eq. 2. By solving the Eq.2, the practical recipe for the given sample could be obtained. Table 1 Theoretical recipe and practical recipe of the samples Entry No.
Practical recipe [%owf]
Theoretical recipe [%owf]
B-79
R-167
O-30
B-79
R-167
O-30
1
0.250
0.250
0.250
0.354
0.102
0.190
2
0.500
0.500
0.500
0.418
0.106
0.326
3
1.000
1.000
1.000
0.627
0.094
0.439
4
1.500
0
1.500
0.871
0
0.540
5
2.000
0
2.000
1.115
0
0.645
Based on the above mentioned approach, the calibrated theoretical recipes of the known samples are listed in Table 3. Comparing the data in Table 3 and that in Table 1, the calibrated theoretical recipes of each sample were approximate to the practical recipe, which indicated that the accuracy of the color matching system improved after the calibration.
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Table 2 Calibration coefficients Entry No.
Calibration coefficient B-79
R-167
O-30
1
1.414
0.102
0.190
2
0.835
0.106
0.326
3
0.627
0.094
0.439
4
0.581
0
0.540
5
0.557
0
0.645
Table 3 Calibrated theoretical recipe Entry No.
Calibrated theoretical recipe [%owf] B-79
R-167
O-30
1
0.268
0.250
0.231
2
0.403
0.482
0.561
3
1.087
1.000
0.914
4
1.655
0
1.585
5
2.557
0
1.878
Tests of the Calibrated Color Matching System. To test the accuracy of the calibrated color matching system, another three samples were dyed with mixed disperse dyes in supercritical CO2. The three samples were used as the standard samples, and its practical recipe and calibrated theoretical recipe are shown in Table 4. It can be seen that, the calibrated theoretical recipe were approximate to the practical recipe, which supported the point that the calibrated color matching system could be used to find the recipe for a given sample.
Table 4 Practical recipe and calibrated theoretical recipe Practical recipe [%owf]
Calibrated theoretical recipe [%owf]
Entry No. B-79
R-167
O-30
B-79
R-167
O-30
6
0.330
0.330
0.330
0.343
0.338
0.333
7
0.660
0.660
0.660
0.676
0.683
0.690
8
1.000
0
1.000
1.014
0
1.047
Conclusions Base on the samples dyed with single dyes of the trichromatic disperse dyes, the database for color matching of PET fibers dyed in supercritical CO2 was established. The accuracy of the established color matching system was verified by several samples dyed with mixed disperse dyes. The initial theoretical recipe of the samples did not agree well with the practical recipe. By adding calibration coefficients, the calibrated theoretical recipes were approximate to the practical recipe, i.e. the calibrated color matching system could be used to find the recipe for a given sample.
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References [1] A. Hou, B. Chen, J. Dai, K. Zhang, Using supercritical carbon dioxide as solvent to replace water in polyethylene terephthalate (PET) fabric dyeing procedures, J. Clean. Prod. 18 (2010) 1009-1014. [2] E. Bach, E. Cleve, E. Schollmeyer, Past, present and future of supercritical fluid dyeing technology—an overview, Rev. Prog. Color. 32 (2002) 88-102. [3] E. Bach, E. Cleve, E. Schollmeyer, Dyeing of fiber in supercritical carbon dioxide-new results. Proc. 8th Meeting Supercrit. Fluids, France, Bordeaux, 2002. [4] L. Tušek, V. Golob, Ž. Knez, the effect of pressure and temperature on supercritical CO2 dyeing of PET-dyeing with mixtures of dyes, Int. J. Polym. Mater. 47 (2000) 657-665. [5] E. Allen, Basic equation used in computer color matching, J. Opt. Soc. Am. 9(1966) 1256-1257.
Eco-Dyeing, Finishing and Green Chemistry 10.4028/www.scientific.net/AMR.441
Establishment of Database of Color Matching System for Supercritical CO2 Dyeing 10.4028/www.scientific.net/AMR.441.708
