Environmentally Friendly Dyeing of PTT with Temporarily Solubilized Azo Diseperse Dyes

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1 w œwz, 45«4y 2008 Textile Science and Engineering Vol. 45, No. 4, 2008 w 266 y eyx x Á½x Á w š lœw q l œ k Environmentally Friendly Dyeing of PTT with Temporarily Solubilized Azo Diseperse Dyes Hae Kyoung Jang, Hae Rim Kim, and Jung Jin Lee Fiber System Engineering Program, Division of Polymer System Engineering, Dankook University, Yongin , Korea (Received June 7, 2008/Accepted August 5, 2008) Abstract: Temporarily solubilized azo disperse dyes containing β-sulfatoethylsulfonyl group were applied to PTT fabric and feasibility of dispersant-free dyeing was investigated. The color yields of the dyes on PTT fabric were found to be dependent on dye bath ph while not much on dyeing temperature. The optimum results were obtained at ph 5-6 and 110 o C-120 o C. The dyes showed good build-up properties on PTT fabric. Washfastness were fair to moderate and lightfastness were somewhat poor. The COD levels of the dyeing effluent from the temporarily solubilized disperse dye were much smaller than those from commercial disperse dyes. Keywords: temporarily solubilized azo disperse dye, PTT, dispersant, dyeing effluent, COD +PVTQFWEVKQP PTT(Polytrimethylene terephthalate) is a fiber material which become popular recently although it was originally developed on 1941 by Whinfield and Dickson. It has several attractive properties as a fiber such as good softness and resilience, easiness of dyeing, and great soil resistance and antistaticity [1,2]. Disperse dyeing of hydrophobic fiber such as PTT and PET is usually performed in the presence of dispersant (dispersing agent). Dispersants are added to increase solubility of disperse dye and to maintain dispersion stability during dyeing procedure. However, they may cause staining of the fabric. They are also discharged as effluents with the residual dyeing liquor, which increases the COD and BOD values of the effluent [3]. In an effort to overcome some of the environmental problems associated with the use of dispersant, our group prepared temporarily solubilized azo disperse dyes containing β-sulfatoethylsulfonyl group and investigated the feasibility of dispersant-free polyester dyeing [4,5]. The terminal sodium sulfate group of the dye confers on sufficient water solubility at room temperature without the aid of dispersants. During the dyeing procedure, the soluble dye is gradually converted to insoluble form as the β-sulfatoethylsulfonyl group is hydrolyzed into vinylsulfone group through β-elimination reaction (Scheme 1). Then the water-insoluble form of the Correspondence to Jung Jin Lee (jjlee@dankook.ac.kr) 6JG-QTGCP(KDGT5QEKGV[ dye having substantivity to hydrophobic polyester fiber such as PTT and PET can be adsorbed onto the fiber. Our group has reported several works about synthesis of the temporarily solubilized disperse dyes containing β- sulfatoethylsulfonyl group and dyeing properties of the dyes on PET and PET/Cotton blend [6-9]. The temporarily solubilized disperse dyes were successfully dyed on PET fabric without using dispersants and they exhibited moderate to good fatness properties. Recently, many researchers had reported a paper about PTT dyeing with disperse dyes [1,10,11]. However, application of the temporarily solubilized azo disperse dyes to PTT fiber has not been studied yet. In this study, dispersant-free dyeing Scheme 1. Conversion of β-sulfatoethylsulfonyl group into vinylsulfone group of the temporarily solubilized azo disperse dyes. 220

2 w266 y eyx 221 of the temporarily solubilized azo disperse dyes on PTT fabric was investigated. Color fastness and build-up properties of the dyes have also been examined. Environmental aspects of the temporarily solubilized disperse dyes was evaluated by measuring COD value of the dyeing effluent and compared with those of commercial disperse dyes. 'ZRGTKOGPVCN /CVGTKCNU Scoured, woven PTT fabric (plain, warp: SDY 75d/72f, weft: SDY 75d/72f, weight: g/m 2 ) was obtained from Huvis Co. Three temporarily solubilized azo disperse dyes were prepared by previous method [8], and their structures are given in Table 1. Commercial disperse dyes (SE type) were supplied by Kyung-In Synthetic Co. The commercial name and C.I. generic name of the dyes are shown in Table 2. All the other reagents used were of laboratory grade. &KURGTUCPVHTGG&[GKPIQH266 PTT fabrics were dyed in an IR dyeing machine without using any dispersant. The dyebaths were prepared with temporarily solubilized azo disperse dye and buffered as follows: at ph 4 and 5 with sodium acetate (0.05 M)/acetic acid; at ph 6, 7 and 8 with sodium dihydrogen phosphate (0.05 M)/disodium hydrogen phosphate; at ph 10 with sodium dihydrogen phosphate (0.05 M)/trisodium phosphate. The dye concentration was 0.2, 0.5, 1, and 2% owf, and liquor ratio was 20:1. Table 1. Temporarily solubilized azo disperse dyes used in this study Dye Structure Table 2. Commercial disperse dyes used in this study Dye Commercial name C.I. Generic name Cdye 1 Synolon Yellow K-4G C.I. Disperse Yellow 211 Cdye 2 Synolon Red K-F3BS C.I. Disperse Red 343 Cdye 3 Synolon Blue K-BR C.I. Disperse Blue Dyeing was commenced at 70 o C. The dyebath temperature was raised 1.5 o C/min to o C, maintained at this temperature for 60 min and rapidly cooled to room temperature. The dyeings were rinsed and reduction cleared in an aqueous solution of 2 g/l sodium hydroxide and 2 g/l sodium hydrosulfite at 80 o C for 10 min. /GCUWTGOGPVUQH%QNQT;KGNFCPF(CUVPGUU The color parameters of the dyed PTT fabric were determined on a Macbeth coloreye 3100 spectrophotometer, under illuminant D65 using 10 o standard observer. The dyed fabrics (dye concentration : 1% owf) were subjected to wash (ISO 105-C06/C2S:1994) and light (ISO 105-B02:1994) fastness tests after tentering at 160 o C for 60s. The shade change, together with staining of adjacent fabrics, was rated according to appropriate grey scale. %1&#PCN[UKUQH&[GKPI'HHNWGPV PTT fabrics was dyed with temporarily solubilized disperse dyes (Dyes 1-3) without using dispersant and also dyed with commercial disperse dyes (Cdyes 1-3) using dispersant. Before and after dyeing, dyeing liquor of 100 ml was collected and than COD Mn values of the dyeing liquor was measured according to the test method in KS M GUWNVUCPF&KUEWUUKQP &[GKPI2TQRGTVKGU As shown in previous studies [4,5], ph condition and dyeing temperature are important factors in dyeing of temporarily solubilized disperse dyes containing β-sulfatoethylsulfonyl group because these factors are closely related to the conversion rate of the soluble form into insoluble vinylsulfone form. In the initial stage of dyeing, the dyes are soluble in dyeing liquor but do not have enough substantivity to the hydrophobic PTT fiber yet. After the conversion reaction gradually occurs during the dyeing procedure, the dyes can then be dyed onto the fiber. Therefore, it is important to investigate the effect of ph condition and dyeing temperature on the color yield of PTT fabric. Figure 1 shows the color yield of Dye 1 on PTT fabric at various ph values and at 110 o C. At ph 4, dyeing rate was slow and color yield was unsatisfactory which is due to the low conversion rate of the soluble dye into the insoluble form. Good color yields were obtained at ph 5 and over and final K/S values were similar to one another although dyeing rates were different. Dyeing curves at ph 5 and 6 seemed to be the best and similar to that for the PET fabric at optimum dyeing condition. Figure 2 shows the color yield of Dye 1 on PTT fabric at various dye concentrations and dyeing temperatures while dyeing ph was fixed to 5. On the whole, K/S values increased as the amount of the dye increased, which suggested that Dye 1 exhibited good build-up on PTT fabric. Higher color yield was obtained at higher dyeing temperature Textile Science and Engineering, Vol. 45, No. 4, 2008

3 222 x Á½x Á except that when 2% owf of dye was applied, K/S value of the PTT dyed at 110 o C was bigger than that at 120 or 130 o C. Figure 1. Effect of ph on color yield of dye 1 on PTT fabric (dyeing concentration: 1% owf, dyeing temperature: 110 o C). Generally, dyeing temperature did not affect the color yield of PTT so much. Figure 3 shows the effect of dye concentration and dyeing ph on color yield of Dye 1 on PTT fabric dyed at 120 o C. Low color yield was obtained at ph 4 which is consistent with the results in Figure 1. At ph 5 and over, Dye 1 exhibited satisfactory color yield. From the results in Figures 1-3, PTT fabric was successfully dyed with the temporarily solubilized disperse dye without using dispersant. Optimum dyeing ph was concluded as ph 5-6 considering good color yield, level dyeing, and compatibility of commercial dyeing condition. Dyeing temperature of o C would be good for dyeing although color yields at 110 to 130 o C were not largely different. %QORCTKUQPYKVJ%QOOGTEKCN&KURGTUG&[GU For comparison of the temporarily solubilized disperse dyes (Dyes 1-3) with the commercial dyes, SE type of commercial disperse dyes (Cdyes 1-3) were selected after considering that PTT fiber in this study would be dyed at o C. PTT fabrics were dyed with both dyes under the same dyeing conditions (1% owf, ph 6, and 120 o C) except that dispersant were only used for the commercial dye and not for the temporarily solubilized disperse dye. Fastness property and COD value of dyeing effluent were compared. Figure 4 and Table 3 show K/S values and color data of Figure 2. Effect of dye concentration and dyeing temperature on color yield of dye 1 on PTT fabric (dyeing ph: ph 5). Figure 4. K/S values of PTT fabrics dyed with temporarily solubilized disperse dyes (Dyes 1-3) and commercial dyes (Cdyes 1-3) (dyeing temperature: 120 o C, dyeing ph: ph 6, dyeing concentration: 1% owf). Figure 3. Effect of dye concentration and dyeing ph on color yield of dye 1 on PTT fabric (dyeing temperature: 120 o C). Table 3. The color data of Dyes 1-3 or commercial dyes (Cdyes 1-3) on PTT fabrics Dyes CIE L * a * b * values ISCC-NBS color L * a * b * name Dye Vivid reddish orange Dye Dark violet Dye Dark blue Cdye Vivid yellow Cdye Strong red Cdye Deep blue w œwz «y

Dye 2 4-5 3 5 2 5 5 3 2 Dye 3 4-5 3 5 2 5 5 3-4 2 Cdye 1 4-5 3 5 2-3 5 5 4 4 Cdye 2 4-5 2-3 5 2 4-5 5 3-4 3 Cdye 3 4-5 4 5 2-3 4-5 4-5 4-5 3 both dyes.

4 w266 y eyx 223 Table 4. Wash & lightfastness of PTT dyed with Dyes 1-3 or commercial dyes (Cdyes 1-3) Washfastness Dyes Staining Lightfastness Change Acetate Cotton Nylon Polyester Acryl Wool Dye Dye Dye Cdye Cdye Cdye both dyes. K/S values of the six dyes were between 17 and 21, which suggests that color depths of the dyes are not largely different from one another. Dyes 1-3 exhibited reddish orange, violet, and blue color on PTT, which is similar to the result on PET fabric. Commercial dyes (Cdyes 1-3) showed yellow, red, and blue color on PTT, respectively. Table 4 shows the results of wash and light fastness tests. Washfastness of Dyes 1-3 were good for the color change but moderate for the staining on multifabrics. Especially, ratings of staining on acetate and nylon adjacent fabrics were fair to moderate and that on wool was moderate. Cdyes 1-3 showed better wash fastness for staining by 0.5 to 1 rating when compared to Dyes 1-3. Lightfastness of Dyes 1-3 were somewhat poor while commercial dyes exhibited moderate fastness. In Dyes 1-3, the lightfastness of Dye 1 was better than that of Dye 2 or 3 by 0.5 rating. The result could be explained by considering a theory that the more aggregated the dye in the fiber, the higher its lightfastness [12]. Thus, less substituted Dye 1 would aggregate more easily than the other dyes which contain bulky substituents in their structures. An effort to improve fastness of temporarily solubilized disperse dyes are needed for commercialization of the dyes in PTT dyeings. Figure 5 and 6 show COD Mn levels of PTT dyeing liquor before and after dyeing for temporarily solubilized disperse dyes and commercial dyes. At the initial dyeing stage, COD levels of dyeing liquor for Cdyes 1-3 (484 to 557 mg/l) were higher than those for Dyes 1-3 (267 to 346 mg/l) as shown in Figure 5. In case of dyeing effluent, the difference became outstanding. Thus, in Figure 6, COD levels of dyeing liquor after dyeing for Cdyes 1-3 (394 to 454 mg/l) were still high while those for Dyes 1-3 (24 to 154 mg/l) were much lower than Cdyes. Low COD levels of dyeing effluents for the temporarily solubilized disperse dyes are probably due to the fact that dispersant were not used when applying Dyes 1-3 to PTT. As most dyes should be adsorbed onto the fiber, dyeing effluent would be composed of unexhausted dye and small amount of electrolyte which were added to adjust ph of dyeing liquors. On the other hand, dyeing liquor of commercial dyes exhibited high COD levels at the initial and even final stage of dyeing. In commercial dyeing of PTT, dispersants are contained in commercial dye itself to some extent and Figure 5. COD Mn levels of PTT dyeing liquor before dyeing for temporarily solubilized dyes (Dyes 1-3) and commercial dyes (Cdyes 1-3). Figure 6. COD Mn levels of PTT dyeing liquor after dyeing for temporarily solubilized dyes (Dyes 1-3) and commercial dyes (Cdyes 1-3). added separately for dyeing of PTT to stabilize dye dispersion. Most of the dispersants, not being adsorbed to the fiber, would be left in the dyeing liquor after dyeing and increase the COD levels. %QPENWUKQP Feasibility of dispersant-free dyeing of PTT fiber using temporarily solubilized azo disperse dyes containing β- Textile Science and Engineering, Vol. 45, No. 4, 2008

5 224 x Á½x Á sulfatoethylsulfonyl group was examined and color fastness as well as environmental aspects of the dyes were compared with commercial disperse dyes. PTT fabric was successfully dyed with the dyes without using any dispersant. The color yield of the dyes on PTT fibric was found to be highly dependent on dyebath ph although effect of dyeing temperature was not significant under the studied condition of o C. The optimum dyeing condition was decided as ph 5-6 and o C. Dye 1 showed good build-up on PTT. Washfastness of PTT dyed with Dyes 1-3 were only fair to moderate on the staining acetate, nylon and wool and lightfastness were somewhat poor. The fastness results of commercial dyes were better than Dyes 1-3 by 0.5 to 1.5 ratings. The COD levels of the dyeing effluent from the temporarily solubilized disperse dyes were remarkably smaller than those from commercial disperse dyes, which is probably attributed to whether dispesants are used or not. It is expected that the temporarily solubilized disperse dyes can also be applied to PTT blend fabric such as PET/PTT or PTT/Cotton by environmentally friendly dyeing. #EMPQYNGFIGOGPV The present research was conducted by the research fund of Dankook University in GHGTGPEGU 1. Y. Yang, H. Brown, and S. Li, Some Sorption Characteristics of Poly(trimethylene terephthalate) with Disperse Dyers, J Appl Polym Sci, 2002, 86, Y. J. Hwang, M. G. McCord, and B. C. Kang, Helium/ Oxygen Atmospheric Pressure Plasma Treatment on Poly (ethylene terephthalate) and Poly(trimethylene terephthalate) Knitted Fabrics, Fiber Polym, 2005, 6(2), S. Y. Lin, A New Lignosulfonate Dispersant for Dyes, Text Chem Color, 1981, 13(11), W. J. Lee and J. P. Kim, The Rate of Hydrolysis of Temporarily Solubilised Disperse Dyes, J Soc Dyers Colour, 1999, 115, W. J. Lee and J. P. Kim, Dispersant-free Dyeing of Polyester with Temporarily Solubilised Disperse Dyes, J Soc Dyers Colour, 1999, 115, J. J. Lee, N. K. Han, W. J. Lee, J. H. Choi, and J. P. Kim, Dispersant-free Dyeing of Polyester with Temporarily Solubilised Azo Disperse Dyes from 1-Substituted-2- hydroxypyrid-6-one Derivatives, Color Technol, 2002, 118, J. J. Lee, N. K. Han, W. J. Lee, J. H. Choi, and J. P. Kim, One-bath Dyeing of a Polyester/Cotton Blend with Reactive Disperse Dyes from 2-Hydroxypyrid-6-one Derivatives, Color Technol, 2003, 119, J. J. Lee, W. J. Lee, and J. P. Kim, Dispersant-free Dyeing of Polyester with Temporarily Solubilized Azo Disperse Dyes from Indole Derivatives, Fiber Polym, 2003, 4(2), J. J. Lee, W. J. Lee, J. H. Choi, and J. P. Kim, Synthesis and Application of Temporarily Solubilised Azo Disperse Dyes Containing β-sulphatoethylsulphonyl Group, Dyes Pigments, 2005, 65, Y. Yang, S. Li, H. Brown, and P. Casey, Dyeing Behavior of 100% Poly(trimethylene terephthalate) (PTT) Textiles, Text Chem Color Am D, 1999, 1(3), S. Yoon, T, Kim, Y. Lim, and K. Cho, The Interpretation of Dyeing Behavior of Poly(trimethylene terephthalate) Fiber with a Disperse Dye, J Koean Soc Dyers Finishers, 2001, 13(4), P.G F. GordonG and P. Gregory, Organic Chemistry in Colour, Springer-Verlag, NY, 1987, pp w œwz «y

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