Electrostatic selfassembly dyeing of cotton fabrics

doi: 10.1111/j.1478-4408.2011.00328.x

Electrostatic self-assembly dyeing of cotton fabrics S¸ ule S Ug˘ura,* and Merih Sarııs¸ ıkb

Coloration Technology

a

Department of Textile Engineering, Su ¨ leyman Demirel University, Isparta 32260, Turkey Email: [email protected] b

Department of Textile Engineering, Dokuz Eylu ¨ l University, _Izmir 35160, Turkey

Received: 28 September 2010; Accepted: 21 June 2011 A new approach to the dyeing of cotton fabrics using an electrostatic self-assembly method was evaluated. Cotton fabrics were pretreated with 2,3-epoxypropyltrimethylammonuium chloride and cationic charges were produced on the fabric surfaces. For the dyeing of cotton fabric, reactive and acid dyes were used. Oppositely charged anionic reactive ⁄ acid dyes and cationic poly(diallyldimethylammonium chloride) were alternately deposited on the surface of cationised cotton fabrics. Ten multilayer films of dye ⁄ poly(diallyldimethylammonium chloride) were deposited on the cotton fabric surfaces using a padder. The build-up of the multilayer films and the level of colour strength (K ⁄ S) achieved are discussed. Samples of cotton fabrics were also dyed with the same dyes, but using the exhaust method, and both types of dyed samples were compared. The washing, rubbing and light fastness properties were evaluated for the dyed fabrics.

Introduction In the early 1990s, after Decher’s group rediscovered electrostatic self-assembly (ESA) or layer-by-layer (LbL) deposition processing, the interest in fabricating multilayer thin films from oppositely charged polyelectrolytes increased in various fields of science. The layer-by-layer process is based on the alternating adsorption of charged cationic and anionic species, such as charged molecules, nanoparticles, dyes, proteins and other supramolecular species [1,2]. Multilayers containing nanoparticles have been studied extensively for their potential use in various fields of science (e.g. anti-static coatings for plastics, sensors, light-emitting diodes, fuel cells, polymer capsules, etc.). Polyelectrolyte selfassemblies of different textile fibres and structures were studied in general and these studies investigated only the possibility of using the electrostatic self-assembly method for textile materials [3–6]. In our previous studies, we investigated the possibility of nanoparticle film deposition on cotton fabrics with electrostatic self-assembly deposition, and we showed that the electrostatic selfassembly process could be used to obtain functional textiles with antimicrobial, ultraviolet (UV)-protective, self-cleaning and flame-retardant properties [7–9]. Cotton is dyed with a range of dye types, such as vat, reactive and direct dyes. In current practice, reactive dyes are predominantly used for cotton dyeing because of their high wet fastness, brilliancy and wide range of hue. However, most commercially available reactive dyes show low binding to cotton, so high concentrations of sodium chloride or sodium sulphate in the dyebath are required to enhance dye–fibre interactions. At the present time, the process of dyeing cotton fabrics with direct and reactive dyes generally requires a high quantity of energy and water and is, in addition, a process that generates high levels of pollution. Cotton fibres are negatively charged attributable to the presence of carboxyl and hydroxyl groups. Cotton can be 372

Society of Dyers and Colourists

easily dyed but the cellulose–dye bond is not very strong. One method of avoiding this problem is to cationise the cotton fibre by using cationic agents that increase the colour strength of the dyeing process and improve the wash fastness [10,11]. Extensive research has already been carried out on the cationisation process and the dyeing process of cationised fibres [11–17]. Hauser and Tabba introduced a chemical process aimed at improving the affinitiy of cotton for anionic dyes [10] by creating cationic charges on the surface of the cotton via epoxy substitution. Anionic dyes are of interest to the textile industry as they improve colour fastness in cotton goods while reducing dyeing times, energy consumption and the use of water [10]. Studies in this area are critical for improving the dyeing process from theoretical, technological, ecological and economical points of view. The pretreatment of cotton to enhance its dye adsorption using commercial cationic agents such as Matexil FC-PN, Matexil FC-ER (ICI Surfactants, Canada), Sandene 8425 (Courtaulds, UK and Clariant [formally Sandoz], Switzerland) and Solfix E (Ciba-Geigy, USA) has been explored; it was found that such pretreatment increased the colour strength of the dyeing and improved wash fastness [18–21]. Successful deposition of nanolayers onto cotton fibres and textiles via electrostatic self-assembly could open up an avenue of dyeing fibres using this method. In this study, we examined the possibility of dyeing cationised cotton fabrics by using an electrostatic self-assembly method with reactive and acid dyes and proved that dye ⁄ polyelectrolyte-based multilayer films can be created with the electrostatic self-assembly process.

Experimental Mercerised and bleached woven cotton fabrics were used as a substrate for the electrostatic self-assembly process. The cationisation process was used to generate cationic sites on the surface of the cotton fibres [10]. The cationic cotton fabric was prepared by using 2,3-epoxypropyl

ª 2011 The Authors. Coloration Technology ª 2011 Society of Dyers and Colourists, Color. Technol., 127, 372–375

Ug˘ur and Sarııs¸ ık Electrostatic self-assembly dyeing of cotton

+

n

N CH3

H3C 2

1

Figure 1 Chemical structure of 2,3-epoxypropyl trimethylammonium chloride (1) and Poly(diallyldimethylammonium chloride) (2)

trimethylammonium chloride (EP3MAC) (Figure 1). 2,3Epoxypropyl trimethylammonium chloride was prepared in an aqueous solution by reacting 3-chloro-2hydroxypropyltrimethylammonium chloride (CHP3MAC) with sodium hydroxide (NaOH). As EP3MAC reacts with the hydroxyl groups of cellulose, cationic charges on the surface of the sample were created. CHP3MAC (65%) and sodium hydroxide crystals were obtained from Aldrich (USA). One hundred grams of CHP3MAC and 45.5 g of sodium hydroxide were mixed into 200 ml of deionised water. The EP3MAC solution was pad applied to the cotton specimens at 100% wet pick-up and fabric samples were kept for 24 h under ambient conditions (20 C and 65% relative humidity) in Ziploc bags. The cationised cotton fabrics were dried in a commercial dryer at 60 C. Reactive and acid dyes (Remazol Brilliant Blue R spec, Remazol Brilliant Red 3BS gran, Telon Red M-3B 80%, Telon Turquoise M-5G 85%) were used for the dyeing process and were purchased from DyStar (USA). The concentration of dye solution was adjusted to 2% wt. Poly(diallyldimethylammonium chloride) (PDDA), molecular weight 100 000–200 000, was purchased from Aldrich (see Figure 1) and used as received. An aqueous solution of the polyelectrolyte was prepared at concentrations of 3 mM l)1 using deionised water. For the reactive or acid dye ⁄ PDDA multilayer films deposition process, the positively charged cotton fabrics were immersed into the following solutions alternately: (i) the anionic dye solution, (ii) the deionised water, (iii) the cationic PDDA solution, (iv) the deionised water (Figure 2). Ten dye ⁄ PDDA multilayer films were deposited on the cotton fibres by using a laboratory-type padding machine. Multilayer films deposited on cotton fabrics were cured at 150 C for 3 min. The cotton fabrics were dyed with the reactive dyes by the pad–dry method to compare the results. For the

reactive dyes, the pad–dry dye solution was: 2 g ⁄ l wetting agent, 100 g ⁄ l urea, 50 g ⁄ l sodium silicate (Na2SiO3), 2% dye and alkaline (pH 11). Untreated and cationised cotton fabrics were dyed with acid dyes using the pad–dry method. The pad–dry dye solution for the acid dyes was: 2 g ⁄ l wetting agent, 4 g ⁄ l levelling agent, 2% dye and acetic acid (pH 4). After padding with the reactive and acid dyes, the fabrics were dried at 60 C, cured at 150 C and washed with warm, hot and cold washing processes. A Minolta 3600d spectrophotometer (_Ipliksan Co., Turkey) was used to obtain the colour strength (K ⁄ S) values of the dyed samples with the layer-by-layer and pad–dry dyeing processes. The washing fastness of the dyed cotton fabrics was tested according to TS EN ISO 20105-C01 [22] using a laboratory-type washing machine (Gyrowash; James Heal, UK), rubbing fastness according to TS EN ISO 105-X12:1993 [23] using a crockmeter and light fastness according to TS 1008 EN ISO 105 B02 [24] using an Atlas Xenotest Alpha light fastness apparatus (Weiss Gallenkamp, UK).

Results and Discussion Figure 3 illustrates the K ⁄ S values of the samples dyed with Reactive Red and Reactive Blue dyes by the electrostatic self-assembly and pad–dry methods. The colour strength values of the reactive dyes (2% owf) are significantly higher for the electrostatic self-assembly dyed cationised cotton than for the pad–dry dyed untreated cotton. The K ⁄ S values of the fabrics dyed using the pad–dry method with the Reactive Red and Reactive Blue dyes can be obtained between layers 6–8 with the electrostatic self-assembly method. Figure 4 illustrates the K ⁄ S values of the samples dyed with Acid Red and Acid Blue dyes by the electrostatic

Reactive Red ESA

Padding

10 Layer number

O

CI–

CH3 + – N CH3 CI CH3

24.65

8

22.632

6

21.669 18.749

4 13.249

2

22.214 Wash

Dyebath

Fabric

Reactive Blue ESA

Polyelectrolyte solution

3

Wash

4

Layer number

2

1

Padding 18.121

10 8

16.828 13.897

6 11.117

4 2

7.299 15.916

Figure 2 Schematic representation of the electrostatic selfassembly dyeing process

Figure 3 K ⁄ S values of the dyed fabrics with reactive dyes


373


Acid Red ESA

Padding 15.462

10 11.53

Layer number

8 6

9.2425

4 2

7.9354 4.9617 8.344 Acid Blue ESA

Padding 23.721

Layer number

10 8

Padding acid dyes onto cationised cotton caused tailing issues for both red and blue dyes. The reason for this problem is that the dyes exhausted onto the fabric very quickly; but with the electrostatic self-assembly method, the dyeing tailing problem was not observed. Table 1 shows the washing (staining and colour change), rubbing (wet and dry) and light fastness results of the dyed samples by both the electrostatic selfassembly and pad–dry methods. The washing and rubbing fastness test results of the dyed samples that were obtained by the electrostatic self-assembly and paddry methods were similar, with the differences between the values being no greater than a half value. For the light fastness properties, the electrostatic self-assembly dyeing results are either the same or higher than the pad–dry method.

23.126 22.632

6 4

20.656

2

15.812 17.579

Figure 4 K ⁄ S values of the dyed fabrics with acid dyes

self-assembly and pad–dry methods. The K ⁄ S values of the acid dyes (2% owf) are significantly higher for the electrostatic self-assembly dyed cationised cotton than for the pad–dry dyed cationised cotton. Using the pad–dry method, untreated and cationised fabrics were dyed. The untreated fabrics gave 0.40 and 0.24 K ⁄ S values for Acid Red and Acid Blue dyes by this method, respectively. Untreated cotton could not be dyed to useful depths of shade with the acid dyes because of the lack of affinity between the fibre and the anionic acid dye molecules. However, cationised cotton strongly attracts acid dyes, allowing the cotton to be dyed to good strengths of colour. The colour strength values of the fabrics dyed by the pad–dry method with Acid Red and Acid Blue dyes can be obtained near the fourth layer using the electrostatic self-assembly method. For the fabrics dyed by electrostatic self-assembly, the K ⁄ S values increased as the layer number increases.

Conclusions The use of the electrostatic self-assembly method to deposit dye ⁄ polyelectrolyte multilayers on cotton fibres is reported. Pretreatment of cotton with 2,3-epoxypropyl trimethylammonium chloride (EP3MAC) was used to create positively charged fibres. Cationised cotton can be dyed without auxiliary chemicals with a variety of reactive and acid dyes to give excellent colour yields using the electrostatic self-assembly method. The colour fastness (washing, rubbing and light) of electrostatic selfassembly dyeing is equal or superior to the colour fastness of the same dyes by the pad–dry method. The K ⁄ S of the electrostatic self-assembly dyed samples was at all times higher than that of the pad–dry dyed samples. Higher K ⁄ S values are obtained with electrostatic self-assembly dyeing with between 6 and 8 layers for reactive dyes. With acid dyes, the K ⁄ S values were higher than the cationised cotton pad–dry dyed samples near the fourth layer. The dyeing procedure for electrostatic self-assembly uses less water and fewer chemical auxiliaries and requires less energy than the pad–dry method. So, by the electrostatic self-assembly method, not only was pollution from auxiliary chemicals eliminated, but the efficiency of dye utilisation was also enhanced. These results indicate the feasibility of using the electrostatic self-assembly method to dye cotton fibres.

Table 1 Fastness test results of the fabrics

Dyestuff Reactive

Remazol Red Remazol Blue

Acid

Telon Red Telon Turquoise

374

Washing fastness

Rubbing fastness

Dyeing method

Staining

Colour change

Dry

Wet

Light fastness

Pad–dry ESA Pad–dry ESA Pad–dry ESA Pad–dry ESA

4 4⁄5 4 3⁄4 4⁄5 4 4 4⁄5

4⁄5 4⁄5 4 4 4⁄5 4⁄5 4⁄5 4⁄5

4 4⁄5 4⁄5 4 4 4⁄5 4⁄5 4⁄5

3 4 3⁄4 3 3 3 3 3

3⁄4 4 3 3 3 3 3 4



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