Study On The Darkening Finishing Of Black Wool Fabric

Black wool fabric, which is widely used as clothes material, should have pure black shade,gentle handle, clear surface structure and good elasticity. Recently, color-darkening finishing ofblack wool fabric has become a research hotspot among textile enterprises.In this research, chitosan pre-treatment, protease treatment and finishing with low-refractiveindex darkening agents (fluorine and polyurethane resins, etc.) were employed to achievedarkening effect. The L value of black wool fabric treated with two proteases (Espraze8.0L andSavinaze16.0L) for minutes was reduced by0.5at most. The darkening effect could also be easilyobserved by eyes. However, more notable darkening effect was obtained by finishing withlow-refractive index darkening agents.Darkening agents with low-refractive index (fluorine and polyurethane resins) were appliedonto wool fabric by high-uptake padding process and remarkable darkening effects were achieved.Agents with low-refractive index were first applied onto the fabric by immersing process. Then,excess liquid was removed without padding to increase the uptake as high as possible. Optimalexperimental conditions were determined by single factor and orthogonal experiments: theconcentration of color darkening agents TG-5243, HH-110and penetrating agent SN-10was0.75g/L,6.75g/L and0.175g/L, respectively; bath ratio was1:20, treating temperature was25℃and treating time was30min; after immersing, the treated fabrics were dried at110℃for5min andcured at170℃for3min. The L value of treated fabric reduced to9.617, which was30%lessthan untreated samples,19%less than samples treated with traditional padding method. Besides,the influences of temperature, humidity, oxygen, light on the stability of darkening effect werestudied respectively.Based on the mechanism of anti-reflective film, multistep padding method was employed inthis research to apply three kinds of color-darkening agents with different refractive index(fluorine, polyurethane and silicon resins) on black wool fabrics. Compared with one-step paddingprocess, more notable darkening effect was obtained with this multistep treatment. By two-steppadding (HH-110, TG-5243), the L value of treated fabric reduced to10.115, which was13%lessthan samples treated by one-step padding process; by three-step padding (HH-110, TG-5243, SI),the L value of treated fabric reduced to9.785, which was16%less than samples treated byone-step padding process. Then, based on the surface topography of treated wool, the mechanismof this notable effect was investigated from the point of optics. Besides, compared with samplestreated by high-uptake padding process, samples treated by multistep padding process showedbetter stability of darkening effect. Compared with traditional one-step padding method, thedarkening effect of black wool fabrics treated by multistep padding method was improved afterdecatizing.