Study On Fading And Cross-color Behavior Of Cotton Fabrics In Washing Process

Cotton fabrics are popular because of their softness,comfort and good warmth.Therefore,cotton fabrics are very common in people’s daily life.In the household washing process,the proportion of cotton fabrics are dyed with reactive dyes is large,and the garments are repeatedly washed,so that fading and cross-coloring often occur during the washing process.The main reasons for the fading of the fabric are:the action of the surfactant in the detergent causing the dye molecules to fall;the process such as sun exposure causes the dye molecules to oxidize or reduce the fastness to the fabric;the temperature of the fabric during the washing process is too high causing the hydrolysis of covalent bonds.The cross color of the fabric refers to the phenomenon that the color caused by the simultaneous washing of the dark fabric and the light fabric is transferred from the dark fabric to the light fabric.In the daily washing,the above phenomenon will occur,and the influence of mechanical force on the fading of the fabric is well known.However,there are few systematic studies in this aspect,and there are insufficient understandings of the fading and cross-color behavior.Most of the existing studies still stay in qualitative analysis.Therefore,there is a need to develop new methods for exploring the dye drop process and the cross-color process,which facilitates a deeper understanding of the fading and cross-color behavior of the fabric during home washing.In this paper,the active black 5 dyeing and mixed dye-dyed cotton knitted fabrics were first studied.The amount of dye falling off from the cotton fabric during the washing process were quantitatively studied by UV-Vis and other techniques.The results show that during the washing fading process,the dye falling off the fabric is composed of the dye in the residual liquid and the dye on the fractured short fibers.After repeated washing,the proportion of dye on the short fibers is large,and the mechanical force is the main factor affecting the amount of dye on the short fibers,and the hydrophilicity of the cloth sample becomes better.The strong mechanical force causes damage to the surface of the cloth sample,leading to the decrease of the K/S value of the cloth sample and the increase of color difference AE.In the washing process,the mechanical force will affect the chromaticity change of the fabric,and the amount of dye on the short fibers is more than that on the white cloth,indicating that the adhesion of the short fibers is the main reason for color change of the cloth.And the dyeing of the free dye on the wash cloth is secondary.Secondly,by testing two different detergents,the fading and cross-coloring that occurred during the washing process were solved.The results show that for the red swatch,the detergent containing anti-coloring agent can effectively prevent the dye cross-dyeing onto the white cloth,and the best effect can be achieved when the concentration is 1.0%.For black swatches,anti-cross-color anti-cross-linking has no effect.For red and black swatches,cellulase can effectively prevent the adhesion of colored short fibers to the white cloth.The cellulase is used at 40℃ when the water hardness is 300 ppm and the pH is 6.5.The detergent with cellulase concentration of 0.4%has the best effect.Finally,the mechanism of cellulase inhibiting the adhesion of the short fibers to the fabric and the change in fabric properties after cellulase treatment were studied.The results showed that:after cellulase treatment,the capillary effect of fabric increased,the wetting time became shorter,and the hydrophilicity became better.Moreover,the weight of the fabric is reduced,the drape coefficient is lowered,the thickness is reduced and the bursting strength is lowered.But the wearing performance of the fabric is not largely affected.Increased whiteness and softness,which is caused by enzyme treatment,give the fabric a soft,smooth feel and a bright color.Due to the increased hydrophilicity of the wash fabric,the adhesion of the dropped short fibers to the wash fabric can be effectively improved by the mechanical force.