Polyester and Polyester Fabrics with

Mar 30, 2007 - The results for pilot-scale dyeings are also compared with those obtained on an industrial scale in a finishing mill. Dyeing using infr...
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Ind. Eng. Chem. Res. 2007, 46, 2710-2714

Continuous Dyeing of Cotton/Polyester and Polyester Fabrics with Reactive and Disperse Dyes Using Infrared Heat Arthur D. Broadbent,* Youssef Mir, Miriem Lhachimi, Julienne Bissou Billong, and Serge Capistran De´ partement de ge´ nie chimique, Faculte´ de ge´ nie, UniVersite´ de Sherbrooke, Sherbrooke, Que´ bec, Canada J1K 2R1

Continuous dyeing of cotton/polyester and 100% polyester fabrics was performed using mixtures of reactive and disperse dyes, or disperse dyes alone, respectively, and achieving dye fixation by heating, using an electric infrared oven situated in front of an electric hot air unit. Generally, the colors of the thermally produced dyeings were reasonably similar to those of the respective exhaust dyeings obtained using the same recipes. As expected, the thermally produced dyeings usually contained more unfixed dyes than the exhaust dyeings, largely a consequence of the quicker and less-efficient post-dyeing washing process. The results for pilotscale dyeings are also compared with those obtained on an industrial scale in a finishing mill. Dyeing using infrared heating and hot air had no influence on the light stability of the colors or on the fabric handle. Most significantly, the negligible variation of color along the fabric length during continuous thermal dyeing illustrated that the process was well-controlled in all cases and could be valuable for the dyeing of small lots of fabric. Introduction Previous papers have described the use of infrared heating for the thermal fixation of reactive dyes on cotton fibers.1,2 Recent studies3 have concentrated on the application of this technology to commercial dyeing. A process in which cotton fabric was impregnated with an alkaline solution of reactive dyes and then dried and heated in an electric infrared oven gave excellent color quality and consistency. “Thermosol” dyeing of polyester is well-known.4 For dyeing cotton/polyester fabrics, the usual sequence of operations is described as follows: (1) impregnation with a solution containing both disperse and reactive dyes; (2) gas infrared predrying; (3) cylinder contact drying; (4) heating in the thermosol oven to temperatures of ∼210 °C, causing vaporization of the non-ionic disperse dyes and their absorption by the polyester; (5) cooling; (6) impregnation with an alkaline solution containing salt; (7) steaming to cause fixation of the reactive dyes on the cotton component; and finally (8) washing to remove unfixed dyes. It is a lengthy process that requires long runs of material for economic success. Because it is usually relatively simple to install a compact electric infrared heating unit in front of a gas-fired hot air drying frame, we envisaged a continuous dyeing process in which a cotton/polyester fabric, impregnated with a solution containing both reactive and disperse dyes, would be dried and heated in the infrared unit, aiding fixation of the reactive dyes on the cotton, and then heated further in a conventional dryer under the conditions of the thermosol process. Ideally, the entire process could be performed using infrared heating, but sublimation of the disperse dyes and their absorption by the polyester fibers requires maintaining a high constant temperature of ∼200 °C for up to 1 min. This is complicated using infrared heating alone and would necessitate careful control of the fabric temperature by modulation of the voltages supplied to the infrared sources. This paper describes the continuous dyeing of a cotton/polyester fabric, on the pilot and industrial scales, * To whom correspondence should be addressed. Current contact information: Department of Chemistry, Bishop’s University, 2600 rue College, Sherbrooke, Quebec, Canada, J1M 0C8. Tel.: (819) 822-9600, X2730. E-mail: [email protected].

with various mixtures of reactive and disperse dyes, using a combination of infrared and hot air heating. The same process was also used for continuous dyeing of a 100% polyester fabric using a mixture of disperse dyes. It is well-known that some disperse dyes used for coloring the polyester component of a cotton/polyester fabric are not stable to the typical alkaline conditions required for effective reaction of reactive dyes with cotton. Because of this, two different types of dyeing systems were examined: (1) dyeing the polyester component with disperse dyes and the cotton with reactive dyes capable of reaction with cellulose under neutral conditions at relatively high temperatures; and (2) dyeing using the more-common reactive dyes, requiring alkaline fixation conditions, but mixed with selected disperse dyes known to be relatively stable to hot alkaline solutions. The dyeing procedures developed in this work represent a continuation of our previous work3 and provide a new thermal dyeing method, based on combining existing dyeing technologies, that will allow the economical continuous dyeing of small lots of cotton/polyester and polyester fabrics. Experimental Procedures Materials. The woven cotton/polyester fabric provided by our industrial partner had a 100% polyester multifilament warp and a 50/50 blended cotton/polyester filling. The warp and filling (weft) yarns in this fabric were of similar number density (reported in terms of number/cm) and weigth density (reported in terms of weight/cm), so the overall composition of the fabric was similar to a 25/75 cotton/polyester ratio. Its superficial weight was 200 g/m2. The 100% polyester filament woven fabric had a superficial weight of 80.0 g/m2. This fabric was included at the request of our industrial partner, to assess the possibility of using the infrared/hot air process for dyeing polyester alone. For the pink and green shades, the reactive dyes used were of the type that will react with the hydroxyl groups of cotton under neutral or weakly alkaline conditions at relatively high temperatures. Such dyes are usually based on a nicotinic acid leaving group bonded to a triazine ring (e.g., Figure 1A). They were applied using a low concentration of Na2HPO4. The

10.1021/ie0700617 CCC: $37.00 © 2007 American Chemical Society Published on Web 03/30/2007

Ind. Eng. Chem. Res., Vol. 46, No. 9, 2007 2711

were compared to those of dyeings obtained by conventional exhaust techniques. For these color standards, the amounts of dyes required per 100 g of fabric were related to the pad dyeing solution recipes using the following equation:

mass of dye (g) ) 100 g fabric mass of dye (g) volume of solution (L) 100 g fabric 1000 mL mass of solution (g) × × L mL mass of solution (g) Figure 1. Partial molecular structures of the reactive groups of typical reactive dyes: (A) nicotinyltriazine, (B) chlorotriazine, and (C) vinyl sulfone.

solutions of dyes also contained dispersing, anti-migration, and wetting agents. The recipes are given in Table 1. The cotton/ polyester fabric was also dyed using a combination of disperse dyes for the polyester component and normal reactive dyes requiring alkaline conditions for reaction with the cotton. The latter are usually based on chlorine or vinyl sulfone reactive groups (e.g., Figures 1B and 1C). These recipes are given in Table 2. The recipe for dyeing the 100% polyester fabric is given in Table 3. All recipes were calculated from those provided by a dyestuffs manufacturer (Tri-tex, Inc.), who also supplied all the dyes. Commercially produced colors are invariably the result of using mixtures of two or more dyes and those given in the tables are typical examples. These recipes were not expected to result in any problems of incompatibility (i.e., problems of variations in dyeing behavior caused by the presence of other dyes or auxiliary chemicals in the solution used for dyeing). Equipment. This consisted of a pad bath (1.0 L) with rubbercovered squeeze rollers, an electric infrared oven (up to 18 kW) through which the fabric passed horizontally, and a hot air unit (15 kW) with the fabric passing up and down over rollers whose positions could be adjusted to give the required residence time at the operating temperature. This equipment has already been described in a previous paper.3 The typical operating temperature was 210 °C, with an air flow of 19 m3/min, most of which was recirculated. Exhaust dyeings for use as color standards were performed in a Zeltex Polycolor laboratory dyeing machine in sealed stainless steel beakers. Continuous Dyeing Operations. The usual pilot-scale dyeing operation consisted of impregnating the 25-cm-wide cotton/ polyester fabric with dye solution (solution pick-up value of ∼75%), passing it through the infrared oven at 2.3 m/min (with a residence time of 38 s and an exit temperature of 110-115 °C), and then passing it through the hot air unit operating at 210 °C (with a residence time of 60 s). After dyeing, the colored fabric was washed. The dyeing and washing procedures have been described previously.3 For the industrial trials, the fabric was 350-400 m long and 1.75 m wide. The same dyeing recipes were used. The equipment was described in the previous paper.3 The fabric temperature at the exit of the infrared oven was typically ∼110120 °C. The drying frame was operated with low air flow at 210 °C, and the fabric residence time was 60 s at a speed of ∼20 m/min. The 100% polyester fabric was continuously dyed on the pilot scale only, using the same conditions as those for the cotton/ polyester fabric. Exhaust Dyeing Procedures. In most cases, the color and properties of dyeings obtained using the thermal dyeing method

Thus, from Table 1, for the dye Trisetile Blue RBL 100%, which requires a bath concentration of 1.12 g/L for the pale green shade, the amount of dye required for exhaust dyeing of 100 g of fabric is given by

mass of dye (g) 1.12 ) 0.084 ) 100 g fabric 1 × 1000 × 1.00 75.0 For neutral dyeing reactive dyes (pink and green shades in Table 1), an all-in-one dyeing procedure was used with a 10:1 liquor ratio and the addition of 40 g/L of Na2SO4·10H2O (Glauber’s salt). Dyeing was performed at 130 °C for 30 min, followed by washing at 100 °C for 10 min. For the dyeings using conventional reactive dyes (peat green and violet shades in Table 2), a two-bath exhaust dyeing method was used. Dyeing with the disperse dyes alone was conducted at 130 °C for 30 min in the presence of a small amount of citric acid at pH 5.0. After rinsing, dyeing in a second bath with the reactive dyes was conducted at 60 °C for 60 min in the presence of 60 g/L NaCl and 20 g/L Na2CO3. Both baths had a 10:1 liquor-tofabric ratio. The final washing was conducted at 100 °C for 10 min, using the same liquor ratio. Analytical Procedures. For each dyeing, the reflectance spectrum of an air-dried sample of fabric was measured over a wavelength region of 380-700 nm, with a 10-nm wavelength interval, using a Diano Match Scan II spectrophotometer. The dye fixation yield was calculated using the integrated values of the Kubelka-Munk (K/S) values (calculated from the reflectance values5) before and after washing: 700

( fixation (%) )



K/S(λ))W

λ)380

× 100

700

(



K/S(λ))U

λ)380

where the subscripts W and U refer to dry samples of the washed and unwashed dyeing, respectively. The reflectance spectra also allowed calculation of the CIELAB color coordinates (L*, a*, and b*) and the CIELAB color difference (∆E).5 Dyeing Quality Evaluation. The tests used to assess the amounts of residual unfixed dyes in the fabric, and also the degree of color fading on exposure to light, were not based on the usual standard methods. The results of the washing tests, and of light-induced fading, were not evaluated by comparison with a Grey Scale or the blue wool standards, respectively.4 Our industrial partner was interested in comparing the small differences in the properties of the thermal and respective exhaust dyeings. Therefore, the following procedures were used,

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Table 1. Recipes Used for Dyeing the Pink and Green Shades on Cotton/Polyester Using Neutral Dyeing Reactive Dyes chemical

pale pink

deep pink

Trisetile Yellow K-5GLS 200% Trisetile Red FBHT 150% Trisetile Yellow Brown L Trisetile Blue RBL 100% Neutrifix Yellow GL Neutrifix Red 3B Neutrifix Blue G Na2HPO4 Lyocoll RDN liquid (dispersant) sodium alginate (anti-migrant) Leonil C50 (wetting agent)

0.024 g/L 0.064 g/L

0.120 g/L 0.320 g/L

0.030 g/L 0.020 g/L 0.003 g/L 1.0 g/L 1.5 mL/L 5.0 g/L

Table 2. Recipes Used for Dyeing Cotton/Polyester Dyeing Using Reactive Dyes under Alkaline Conditions chemical

peat green

violet

Trisetile Yellow Brown L Trisetile Blue RBL 100%, Trisetile Rubine RL 200% Triactive Golden Yellow DF-RL 150% Triactive Red DF-4BL 150% Triactive Navy Blue DF-RGB 150% Na2CO3 (alkali) Lyocoll RDN liquid (dispersant) sodium alginate (anti-migrant) Leonil C50 (wetting agent)

12.5 g/L 11.7 g/L 1.15 g/L 0.950 g/L 0.110 g/L 0.195 g/L 20.0 g/L 2.0 mL/L 20.0 g/L 2.0 mL/L

0.150 g/L 1.20 g/L 0.270 g/L 0.0750 g/L 2.15 g/L 0.225 g/L 20.0 g/L 2.0 mL/L 20.0 g/L 2.0 mL/L

Table 3. Recipe Used for Dyeing a Khaki Shade on 100% Polyester chemical

khaki

Trisetile Yellow Brown L Trisetile Blue F-2GS Dianix Red CC (Dystar) Lyocoll RDN liquid (dispersant) sodium alginate (anti-migrant)

3.17 g/L 1.03 g/L 0.260 g/L 8.0 mL/L 20.0 g/L

because they were considered to be more sensitive than the usual standard procedures, particularly those based on a Grey Scale. The washing test, which was used to assess the amounts of unfixed reactive dyes in the cotton fibers, was conducted for 30 min at 50 °C and has already been described.3 Samples of dyed fabric were also washed with neat acetone to determine the presence of residual disperse dye particles. This test consisted of treating 5.0 g of dyed sample with 50 mL of acetone at room temperature for 10 min. For both the washing and acetone tests, the degree of dye removal was evaluated by measuring the absorption spectrum of the solution from 380 nm to 700 nm at 10-nm intervals and summing the 33 absorbance values (integrated absorbance). In addition, for both tests, the CIELAB color difference (∆E) was calculated from the reflectance spectra of dry samples before and after the treatments. Samples of all dyeings were mounted on a board inclined at an angle of 45° to horizontal and exposed to daylight behind glass for six weeks. The reflectance spectra and K/S values5 were measured before and during exposure at 33 equally spaced wavelengths from 380 nm to 700 nm. The 33 K/S values were summed to give the integrated value. Any decrease in the integrated K/S value was indicative of color fading by the light. In addition, the reflectance spectra of the initial and fully exposed samples were used to calculate the ∆E value that resulted from daylight exposure. The handle of all the dyed fabrics was assessed manually in the laboratory, and by the mill personnel, with particular emphasis on any difference in the handle between exhaust and thermally produced dyeings. Results Preliminary Trials. In the preliminary trials, three major considerations had to be addressed:

0.150 g/L 0.100 g/L 0.016 g/L 5.0 g/L 7.5 mL/L 20.0 g/L

pale green

dark green

0.320 g/L 1.12 g/L 0.313 g/L

1.60 g/L 5.60 g/L 1.57 g/L

0.513 g/L 1.0 g/L 2.0 mL/L 20.0 g/L 2.0 mL/L

2.57 g/L 1.0 g/L 2.0 mL/L 20.0 g/L 2.0 mL/L

Table 4. Results for Pilot-Scale Continuous Dyeing Trials

shade

pick-up (%)

CIELAB color difference, ∆Ea

pale pink dark pink light green dark green violet peat green

73 73 50 50 50 50

1.30 ( 0.1, slightly paler 2.30 ( 0.1, slightly paler 4.87 ( 0.3, yellower, paler 7.64 ( 0.2, yellower, paler 4.30 ( 0.2, paler 5.74 ( 0.4, paler

fixation yield (%)

integrated K/S value

97 ( 2 4.41 ( 0.22 92 ( 1 16.9 ( 0.48 79 ( 3 124 ( 6 74 ( 2 445 ( 32 73 ( 4 1388 ( 46 75 ( 2 1747 ( 51

a Averaged CIELAB ∆E value along the fabric length, with respect to an exhaust dyeing, plus or minus the standard deviation.

(1) The selected reactive and disperse dyes were stable, under the given dyeing conditions; (2) The heating processes in the infrared oven and hot air unit did not involve excessive temperatures likely to cause a deterioration of the handle of the fabric; and (3) Drying of the fabric impregnated with the solution of reactive and disperse dyes did not result in preferential migration of dyes. The first problem was avoided by selecting dyes in consultation with a dye manufacturer (Tri-tex, Inc.). We also avoided the use of NaOH solutions for reactive dye fixation, because early trials showed that this could significantly change the color that is produced. Based on our previous work,3 we quickly established that the impregnated fabric could be dried in the infrared oven and safely heated to an exit temperature of ∼110115 °C. The fabric showed no evidence of stiffness or a rougher handle, provided that the residence time in the hot air unit, operating at 210 °C, did not exceed 60 s. Early in the preliminary trials, the recipe for the peat green shade gave dyeings with uneven coloration and a difference in color of the two faces of the fabric. The addition of 20 g/L of sodium alginate to suppress this preferential dye migration caused such aggregation of the blue disperse dye in the bath that blue spots were then observed on the otherwise uniformly dyed fabric. This dye was replaced by a more-suitable blue disperse dye. As a consequence of this experience, sodium alginate was added to all dye solutions to suppress migration. The recipes listed in Tables 1 and 2 gave uniform dyeings with colors very similar to those of dyeings prepared by conventional exhaust dyeing methods using the same recipes, less the sodium alginate. Dyeing Cotton/Polyester with Disperse and Reactive Dyes. The typical procedure for pilot-scale continuous dyeing of the cotton/polyester fabric with a mixture of reactive and disperse dyes involved impregnating the dry fabric with a solution containing all the dyes and auxiliaries, drying and heating in the infrared oven (2.3 m/min) to an exit temperature of ∼110115 °C, followed by heating at 210 °C for 60 s in the hot air unit. Samples of dyed fabric were then washed to remove any unfixed dyes.3 The results for the pilot-scale trials for the six

Ind. Eng. Chem. Res., Vol. 46, No. 9, 2007 2713 Table 5. Results for Continuous Dyeing Trials in the Mill K/S Value shade

pick-up (%)

pale pink dark pink dark green violet

45 45 64 64

CIELAB color difference,

∆Ea

6.40 ( 0.1, paler 5.90 ( 0.1, paler 6.13 ( 0.4, darkerc 3.83 ( 0.2, darkerc

fixation yield(%)

integrated

calculatedb

84 ( 2 83 ( 1 72 ( 2 66 ( 1

3.00 ( 0.07 9.10 ( 0.1 613 ( 19 1736 ( 32

2.7 10.4 570 1777

a Averaged CIELAB ∆E value along the fabric length, with respect to an exhaust dyeing, plus or minus the standard deviation. b Values of K/S calculated from the integrated values in Table 4 and adjusted proportionately to the solution retention values for the mill trials. c Measured with respect to a pilot-scale continuous dyeing obtained at a lower solution pick-up percentage.

Table 6. Integrated Absorbance Values for Washing Solutions and CIELAB Color Differences, as a Consequence of Washing Pilot-Scale Dyeings

Exhaust Dyeings

shade

integrated absorbance

CIELAB color difference, ∆E

integrated absorbance

CIELAB color difference, ∆E

light green dark green peat green violet

2.5 2.1 14.0 6.1

3.1 1.2 3.0 1.9

1.1 1.3 2.8 1.8

1.7 1.1 0.38 0.18

Mill Dyeings integrated absorbance

CIELAB color difference, ∆E

1.8

1.2

4.0

0.82

Table 7. Integrated Absorbance Values for Acetone Solutions and CIELAB Color Differences, as a Consequence of Acetone Extraction Pilot-Scale Dyeings

Exhaust Dyeings

shade

integrated absorbance

CIELAB color difference, ∆E

integrated absorbance

CIELAB color difference, ∆E

pale pink dark pink light green dark green peat green violet

0.39 1.31 1.6 2.8 34.8 13.5

0.1 0.2 1.3 0.3 1.5 1.2

0.23 0.32 0.4 1.3 3.3 2.3

0.1 0.1 2.0 1.1 0.5 0.18

Mill Dyeings integrated absorbance

CIELAB color difference, ∆E

2.4

0.7

7.2

0.7

Table 8. Rates of Decrease in the Integrated K/S Values and Final CIELAB Color Difference on Light Exposure to Daylight over Six Weeks Pilot-Scale Dyeings

Exhaust Dyeings

shade

rate of decrease of integrated K/S value (per day)

CIELAB color difference, ∆E

rate of decrease of integrated K/S value (per day)

CIELAB color difference, ∆E

pale pink dark pink light green dark green peat green violet

negligible negligible 0.7 2.2 7.7 2.4

∼0 ∼0 2.0 2.1 3.2 2.4

0.5 0.2 9.3 1.8

1.7 1.0 2.5 2.5

recipes studied are given in Table 4. Subsequently, some of the recipes also were used for full-scale dyeing trials, using the infrared and drying equipment at the mill. These results are given in Table 5. Washing, Acetone Extraction, and Light-Fading Tests. The washing tests were conducted to assess the amounts of residual reactive dyes remaining in the final fabrics; those results are given in Table 6. Acetone extraction tests were conducted to evaluate the amounts of unfixed residual disperse dyes in the final fabrics; those results are given in Table 7. The light and dark green shades showed no significant fading over six weeks of exposure to daylight. The peat green and violet shades were much deeper and did fade somewhat for both the infrared and exhaust samples; those results are given in Table 8. Continuous Dyeing of 100% Polyester. Because of the significance of 100% polyester fabrics in our partner’s overall production, we were asked to examine thermal dyeing of such a fabric using the new infrared/hot air dyeing method. Pilotscale continuous dyeing of a woven 100% polyester fabric was conducted under the same conditions used for the previous dyeing of the cotton/polyester fabric using a mixture of disperse dyes for a medium khaki shade (see Table 3). The color obtained was very similar to that of the standard fabric provided by our industrial partner. The average CIELAB color difference along

the fabric, with respect to the mill standard, was ∆E ) 1.12 (very slightly paler), with a standard deviation of 0.10. The dye fixation yield for the pilot-scale dyeing was 99.5%. The integrated K/S value for the pilot-scale dyeing was 59.5, with the mill standard having a value of 60.2. The dyed sample showed very slight light fading over six weeks of exposure to daylight, identical to that of the mill standard. The acetone extraction test gave zero absorbance, which indicated that no residual disperse dye particles were present in the fabric. Much to our industrial partner’s satisfaction, the fabric dyed using the infrared method was essentially identical in all respects to their product. Discussion and Conclusions For the pilot-scale continuous dyeings, which were conducted in the laboratory, there was always some color difference, with respect to the corresponding dyeing prepared by an exhaust dyeing procedure using the same recipe. In most cases, this was mainly a consequence of the thermal dyeings being somewhat paler. This was not surprising, considering the differences in the fixation conditions. Although the same basic cotton/polyester fabric was used in all the pilot-scale and mill trials, different fabric rolls did not always have the same pre-dyeing preparation treatments. Because of this, it was difficult to control the

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retention of solution during padding, which thus also contributed to the observed color differences. This was even more difficult during the mill trials, where the short run of fabric did not allow any change in pad roller pressure. This complicated direct comparison of the results from the pilot-scale dyeings (Table 4) with those from the mill (Table 5). When the integrated K/S values of the pilot-scale dyeings were adjusted proportionately to correspond to the solution pick-up of the mill dyeings, they were much more similar to those of the dyeings conducted at the mill (compare the two right-hand columns in Table 5). What was significant in all these trials was the negligible variation in color along the length of the dyed fabric. This is shown by the small values of the standard deviations of the CIELAB color differences (in the range of 0.1-0.4), the percentage fixation yields (in the range of 1-4), and the integrated K/S values (usually approximately (2%-3%). Visual examination confirmed that the dyeings had no visible lengthwise or lateral color differences, which was a very satisfying result for our industrial partner. A commercial dyehouse must produce specific colors demanded by their clients. The color differences found on changing from exhaust dyeing procedures to the more rapid thermal process described here indicate that some recipe modification would be required to match the colors requested by clients. Despite this observation, the infrared/hot air dyeing process was well-controlled and gave good color consistency along the entire fabric length. Given the compact size of an electric infrared heating unit, in front of a conventional gas-fired drying range, the process is particularly suitable for the continuous dyeing of small lots of fabric, particularly in paler shades where high fixation yields are obtained. The washing tests on the dyeings did not show any particularly significant differences between exhaust and thermally produced dyeings. Staining tests were not conducted, because, in most cases, the degree of color loss into the solution was not particularly significant. The differences that can be seen in Table 6 are mainly a consequence of the more-severe washing procedure that is used for the laboratory exhaust dyeings and also more-effective continuous washing at the mill, compared to the procedure used after continuous dyeing in the laboratory. Only the dark peat green dyeing showed a problematic result. For this deep shade, the acetone extraction test was also not particularly satisfactory. For this extraction test, results were better for the paler shades, as expected. In fact, for both of the pink shades, there was no color loss on washing in water and almost none on acetone extraction. Our industrial partner had some initial concerns that the thermal infrared/hot air dyeing method might reduce the light

stability of the dyed colors. The test procedure used allowed assessment of small differences in fading between corresponding dyeings prepared by exhaust and infrared methods. The results indicated that the thermal dyeing procedure had no influence on the light fastness of the dyeings produced. Compared with normal ranges of dyes, the numbers of either neutral dyeing reactive dyes or alkali-stable disperse dyes are limited. This study only involved a small number of combinations and it was not possible to say whether the procedure with neutral dyeing reactive with regular disperse dyes was superior to the use of regular reactive dyes with alkali-stable disperse dyes. The single continuous dyeing conducted on the 100% polyester fabric was particularly successful with properties almost identical to those of the standard dyed fabric provided by our industrial partner. Given the success of dyeing trials using reactive dyes on cotton,1-3 and the results on dyeing cotton/ polyester and polyester fabrics described here, the thermal dyeing procedure should be applicable to all cotton/polyester fabrics, independent of their fiber compositions. Acknowledgment This project was funded by a co-operative R&D grant from the University-Industry program of the Natural Sciences and Engineering Research Council of Canada and by Hydro-Que´bec and Consoltex, Inc. The authors also gratefully acknowledge the assistance of the Bureau de Liaison Entreprise-Universite´ of Universite´ de Sherbrooke and Tri-tex, Inc. (St-Eustache, Que´bec). Literature Cited (1) Broadbent, A. D.; The´rien, N.; Zhao, Y. Effects of Process Variables on the Fixation of Reactive Dyes to Cotton Using Infrared Radiation. Ind. Eng. Chem. Res. 1995, 34, 943. (2) Broadbent, A. D.; The´rien, N.; Zhao, Y. Comparison of Thermal Fixation of Reactive Dyes on Cotton Using Infrared Radiation or Hot Air. Ind. Eng. Chem. Res. 1998, 37, 1781. (3) Broadbent, A. D.; Bissou Billong, J.; Lhachimi, M.; Mir, Y.; Capistran, S. Continuous Dyeing of Cotton with Reactive Dyes Using Infrared Heat. Ind. Eng. Chem. Res. 2005, 44, 3954. (4) Broadbent, A. D. Basic Principles of Textile Coloration; Society of Dyers and Colourists: Bradford, U.K., 2001. (5) McDonald, R. Colour Physics for Industry, 2nd Edition; Society of Dyers and Colourists: Bradford, U.K., 1997.

ReceiVed for reView January 10, 2007 ReVised manuscript receiVed February 26, 2007 Accepted February 28, 2007 IE0700617