| Denim clothing has always been on the throne of the trend and has a long history and broad prospects.The core of denim keeping fresh in recent years is the continuous innovation of raw materials and the ever-changing washing process.Traditional denim mostly uses cotton and polyester as raw materials,and the fabric is relatively simple,which is difficult to meet people's increasing demand for clothing diversity.In addition,traditional washing processes such as hydrogen peroxide washing process,sodium hypochlorite washing process and potassium permanganate washing process will produce a large amount of printing and dyeing sewage,which is inconsistent with the style of denim that keeps pace with the times.Ozone decolorization technology is widely spread in printing and dyeing sewage treatment.Therefore,this paper uses the ozone decolorization technology to decolorize the new denim raw material bio-based indigo-dyed PA56.Firstly,the effects of ozone treatment time,environmental p H,and moisture content on the decolorization effect of ozone-treated indigo-dyed PA56 fibers were investigated by singlefactor controlled variable method.Then the orthogonal experiment method was used to explore the optimal process parameters of ozone decolorizing indigo-dyed PA56 fiber.The results show that the longer the ozone treatment time,the more serious the surface damage of PA56 fibers,the greater the loss of breaking strength and elongation at break.The mechanical properties of fibers in neutral environment are obviously better than those in acid-alkaline environment,and the moisture content has little effect on the mechanical properties of fibers.It shows that under the condition that the mechanical properties of PA56 fiber treated with ozone remain intact,the best process parameters for decolorization effect are: ozone treatment for 20 min,environmental p H=9,and moisture content of 10%.Secondly,different ozone concentrations and different treatment time gradients were designed to treat indigo dyed PA56 fibers.In this paper,the kinetics of ozone decolorization of indigo-dyed PA56 fibers by ozone decolorization was investigated.Research shows: the whole decolorization process was divided into two stages: fast decolorization and slow decolorization.The pseudo-first-order kinetic models can describe the decolorization process of PA56 fibers dyed with indigo dyed by four different concentrations of ozone.The decolorization process was analyzed by overall and piecewise fitting respectively,and it was shown that the kinetic constants all increased with the increase of ozone concentration,and the higher the concentration,the worse the overall fitting effect.From the color index,it can be seen that the color change of PA56 fiber after ozone decolorization is mainly bluish-green,of which it is obviously bluish.Finally,the ozone washing water was compared with the traditional washing water,and the influence of different washing methods on the indexes of PA56/cotton blended yarn was explored.Research shows: Various washing processes were performed on the PA56/cotton blended yarn,and it was found that the hairiness of the blended yarn would increase after washing,and the yarn itself would be damaged.Water process>Hydrogen peroxide washing process>Ozone washing process>Enzyme washing process.The decolorization effect of potassium permanganate washing process and sodium hypochlorite washing process is the best,and the change rate of K/S value of both reaches 98.31 % and 92.86 %.However,the surface hairiness and weak knots of the two yarns increased,the fiber cohesion decreased,and the mechanical properties decreased more.Ozone washing water has the best washing effect on the premise of ensuring mechanical properties.At the same time,the blended yarns show different hydrophilicity after washing,and from good to bad are the sodium hypochlorite washing process,potassium permanganate washing process,ozone washing process and hydrogen peroxide washing process. |
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