Sci.Int.(Lahore),25(4),823-827,2013 ISSN 1013-5316; CODEN: SINTE 8 623 SOL-GEL TREATMENT OF DIRECT DYED COTTON FABRIC WITH AEROSIL®200 TO ENHANCE WATER REPELLENCY AND FASTNESS PROPERTIES Sidra Saleemi 1 , Atif Ejaz 2 , Rabia Almas 1 , Anwar uddin Tanwari 1 1 Department of Textile Engineering, Mehran University of Engineering and Technology, Jamshoro, Pakistan 2 Schools of Business and Economics, University of Management and Technology Lahore, Pakistan ABSTRACT: Silica nanoparticles were used to develop nano roughness on fabric with an aim to create super hydrophobic direct dyed cotton and to improve fastness properties. Different concentrations of silica nanoparticles were applied by sol-gel technique to explore the effect of the presence of SiO 2 on the repellency of textile fabrics along with Tetraethoxysilane (TEOS) and Tetramethoxysilane (TMOS) as a cross-linking agent. To observe the effect of finish on hydrophobicity and color yield of cotton fabric different tests as spray rating, rubbing fastness, washing fastness and color yield was assessed. Results indicate that the presence of silica nanoparticles played important role in the enrichment of repellency and fastness properties of the textile fabrics. It was observed that silica sol-gel coatings increased the colour depth of dyed samples. Keywords: Cotton, water repellency, silica nanosol, direct dye and fastness properties. INTRODUCTION Nano roughening of textile surface does not allow any water molecule to absorb on the surface [1]. Super hydrophobic nano-roughened surfaces can be prepared by controlling surface topography by various processing methods, such as sol–gel method, organic/inorganic hybrid method, electrochemical method, plasma method, phase separation method, template ,etc. Sol-gel coating not only integrate the technical properties such as super hydrophobic surface but also enhance the existing properties like washing fastness, rubbing fastness and hue of dyed samples [2]. This research was used to generate hydrophobic cotton samples dyed with direct dye by using sol-gel techniques and also enhance the fastness properties of these treated samples. Direct dye is one of the most popular dyes used for cotton due to its significant benefits, such as wide colour ranges, good substantivity, low cost, short dyeing time, and so on [3]. However, its fastness properties, especially wash fastness is poor mainly because of its hydrophilic sulphonic groups in a molecule structure. To enhance the wash fastness of cotton dyed with direct dyes, cationic compounds, resin fixatives, metallic salts, and polyfunctional cross-linking agents, etc. are widely applied [4].However these compounds may cause some disadvantages to properties, also it needs an extra step of applying these chemicals on cotton surface which will increase the cost of product. It has been concluded that the sol-gel method can improve in the wash fastness of direct dyes with silica sol, but only direct black dyes were used [5]. Current work shows that sol-gel coatings may improve the fastness properties of direct dyes other than direct black dyes. Sol-gel coatings prepared by using silica nanoparticles provide good repellency > 90 contact angle [6]. These coatings were prepared by using three steps .i.e. (sol-gel) hydrolysis, (lyogel) condensation and (xerogel) bonds formation [7]. The paper presents the results of water repellency and fastness properties of direct dyed fabric by sol-gel method. These nanosol coatings not only improve the fastness but provide good repellency. EXPERIMENTAL MATERIALS A commercially prepared ready-to-dye cotton woven fabric (136 g/m 2 ) was kindly supplied by M/S Popular Textile Mills Pvt: Ltd Karachi and two widely used commercial direct dyes, Indosol Red-BA and Indosol Black NF/1200, were used for this study. Six chemicals selected in this work were tetraethoxysilane (TEOS) and Tetramethoxysilane (TMOS) and n-octyltriethoxysilane supplied by Hangzhuo Feidian Chemical co. Ltd Shanghai, China, Silica nanoparticals (Aerosil® 200) supplied by Pharmacare Industry Lahore, Pakistan, ethanol (95%) and hydrochloric acid (37%) supplied by Al-Beruni scientific store, Hyderabad, Pakistan. METHODS Bleached cotton samples were dyed (0.5% and 3% o.w.f) with direct dyes, Indosol Red-BA and Indosol Black NF/1200, on Rapid HT dyeing machine with liquor to goods ratio of 20:1. At 40 C dye, Lyogen WD (0.25 -1 g l -1 ) and Common salt (15 g l -1 ) were added and treated for 20-30 mins. The samples were then treated at 90 C for 40-60 mins for the fixation of dye on cotton and then washed according to the method recommend by Clariant [8] and at last dried in an oven. The silica sols were prepared using Ultrasonic cleaner (FRT- 200B). These silica sols are treated at room temperature for 30 mins. A series of silica sol (Sol A to Sol D) in Table 1 was then applied on sample by dipping the fabric in solution evenly, dried at room temperature and cured at 100 C for 1 hour in laboratory oven [6].The treated samples were then stored in air tight polyethylene bags till they were tested. Table 1: Recipe with different concentration of Aerosil® 200 All quantities are in ml except Aerosil®200 Silica Sols Aerosil® 200 Ethanol Hcl TEOS/ TMOS n- octyltrieth oxysilane Sol A - 96 24 20 4 Sol B 0.02% 96 24 20 4 Sol C 0.1% 96 24 20 4 Sol D 0.2% 96 24 20 4