Short wet—steam dyeing process of cotton fabrics with reactive dyes

SUN+Fu-yun　WANG+Zhao-feng　FANG+Kuan-jun

【Abstract】The effects of Reactive Black 5 utilized to cotton fabrics by short wet-steam process on the dyeing properties were investigated. This study will provide a theoretical reference for short wet-steam process of cotton fabrics with bifunctional reactive dyes. The optimal amount of Selilao agent was 20 g/L， while the soaping and rubbing fastness of the dyed cotton fabrics were both reached to 4-5 rating.

【Key words】Cotton fabrics； Bifunctional reactive dyes； Short wet-steam process

0 Introduction

Apparel products made of cotton fibres have the largest share in the textile market[1]. Cotton fabrics were primarily dyed with reactive dyes. Since strong response stability， high fixation？and？dye-up？rate of bifunctional reactive dyes， it is often utilized to cotton fabrics， which given the cotton excellent color fastness[2].

Short wet-steam process was the application of superheated steam or steam mixed with hot air to fixation， overcoming the previous problems caused by dye migration and energy consumption when drying progress[3].

The objective of the present work was focused on the effect of Reactive Black 5 utilized to cotton fabrics by short wet-steam process on the dyeing properties.This study will provide a theoretical reference for short wet-steam process of cotton fabrics with bifunctional reactive dyes.

1 Experimental

1.1 Materials

Desized， scoured， bleached and3/1twill weave cotton fabric， weighing264g/m2， was used throughout the investigation. Reactive Black5was provided by Tianjin Dekai Chemical Co.， Ltd. Selilao agent was provided by The Yellow River Delta textile science and technology research institute. The standard soap flakes were purchased from Macro chemical products factory. Deionised water was used in all experiments. The structure of Reactive Black 5 was shown below.

1.2 Fabric dyeing and color measurements

The fabric samples were padded twice with a solution containing various amounts of reactive dyes and alkali on a laboratory padding mangle. The pick-up rates were approximately 80%for all samples. Then， the fabrics were steaming at 100°C for 3 min. After batching， the washing-off was then carried out by exhaust method followed by heat rinse， soaping off， warm rinse and cold rinse. The color of dyed fabric was measured using a SP60 integrating sphere spectrophotometer （X-Rite， USA）. The relative color strength of the cotton fabric was expressed as the K/S value[4].endprint

1.3 Rubbing and soaping fastness measurements

Rubbing and soaping fastness of the dyed cotton fabrics was tested according to GB/T29865-2013 and GB/T 3921-2008.

2 Results and discussion

2.1 Influence of Selilao concentration on the color values

Selilao is an effective compound alkali agent. As shown in Table 1， increasing the alkaline agent amount from 0 g/L to 20 g/L evidently raised the K/S values from 2.1to 22.8. However， further increasing the alkaline agent amount from 20 g/L to 40 g/L， the k/s values decreased from 22.8 to 20.2. This may be because at higher pH， lower colour yields were obtained on the blend since the dyes became easier to hydrolyze[5].Therefore， the optimal amount of Selilao agent was 20 g/L.

Table1 Effect of Selilao dosage on color index of dyed cotton fabrica

aReactive Black 5， 20g/L； steaming at 100 0C for 3min.

Influence of dye concentration on the color values was presented in table 2. It is clearly that increasing the dye concentration from 5 g/L to 40 g/L resulted in the K/S values enhanced from 6.8 to 21.5 rapidly， while the increase got smaller and smaller. The reason is that although increasing the dye concentration， the number of hydroxyl groups of cotton fibers that react with dyes is fixed， leading to the K/S values enhancement became smaller and smaller[6].

2.2 Effect of dyes concentrations on the color values

Table2 Influence of dye concentration on the color valuesa

aSelilao agent， 20g/L； steaming at 100℃ for 3min.

2.3 Fastness properties of the dyed cotton fabrics a

The soaping and rubbing fastness of the dyed cotton fabrics were given in table 3. The obvious great color fastness of cotton fabrics obtained by Reactive Black 5， reaching to 4-5 rating， where it is absolutely conforming to the requirements of the product.

Table3 Soaping and Rubbing fastness of the dyed cotton fabricsa

aReactive Black 5， 20g/L； Selilao agent， 20g/L.

3 Conclusion

Reactive Black5was utilized to cotton fabrics by short wet-steam process. The optimal amount of Selilao agent was 20g/L， while the soaping and rubbing fastness of the dyed cotton fabrics were both reached to 4-5rating， where it is absolutely conforming to the requirements of the product.

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[6]Tam K Y，Smith E R，Booth J，et al.Kinetics and Mechanism of Dyeing Processes： The Dyeing of Cotton Fabrics with a Procion Blue Dichlorotriazinyl Reactive Dye[J].Journal of Colloid & Interface Science， 1997， 186（2）：387.endprint