Influence Of Laser Bleaching On The Structure And Properties Of Denim Fabrics

This article was researched from the pure cotton yarn, the basic material of denim garment. The changes of cotton yarn, cotton/kapok yarn and polyester/cotton blended yarn in physical properties with laser washing were analyzed. It also research the changes of two different dyes of indigo and sulphur black with laser washing. It compared the effect with laser washing and traditional washing.Laser is an easy, rapid, cost effective and environmental friendly method with high durability. These findings are valuable for industry caring about the environment. The following is the content of the results of the research:This experiment first was researched the physical properties of kapok blended yarn, polyester/cotton blended yarn and cotton yarn with or without laser washing, the results showed that the linear density, tension and strength of 3 different kinds of yarns were all declined slightly. The physical properties of the kapok and cotton blended yarn is the worst, but the kapok fiber is hollow fiber, and its decomposition temperature is higher, so physical performance decline is also relatively minimal; the twist of yarns were nearly unchanged after laser washing; there were no new organic function groups in cotton fabric, so laser is a kind of eco-friendly way to treat the denim fabrics.By setting the different laser power and speed of processing parameters, 4 different component content of indigo denim fabrics were selected to orthogonal experiment, then the physical properties of the denim fabrics with or without laser washing were tested, results showed the physical properties of denim fabrics were changed in direct proportion with speed, and in inversely proportional relationship with power; it is a fact that after laser treatment, the K/S values decreased dramatically; laser washing had different influence on the mechanical properties of denim fabrics, the largest one was for the yarn with dying in warp and weft; the initial mechanical performance of kapok denim fabric was not good, but when the processing power below 80%, it decreased smaller than others; the permeability, rubbing fastness and crease recovery angle were all declined after laser washing; the best processing parameters:power is 80%, speed is 10000 mm/min.The physical properties of indigo and sulphur black with or without laser washing were tested, there were no new organic function groups in this experiment; the K/S values decreased dramatically and the fade effect of indigo fabric was better than sulphur black one; the strength loss of indigo fabric was larger than sulphur black one, the larger gram weight was, the smaller the densities were,the larger strength was; the permeability was declined slightly; there were less changes in the fabric weight loss rate, thickness, wear resistance, resistance to dry wet rubbing fastness and crease recovery angle; the wet rubbing fastness to indigo dye was worse.Different ways of washing caused different effect and physical properties on denim fabrics; the result showed that the biggest changes in physical properties was denim fabrics with laser washing and potassium permanganate bleaching, the K/S values of denim fabric with laser washing was lowest, and the strength, the weight loss rate, the rubbing fastness and crease recovery angle of denim fabric were all reduced significantly with potassium permanganate bleaching although the K/S values was the second lowest; the air permeability of denim cloth was only rose with enzyme bleaching; the thickness of all denim fabrics were not changed; in general, laser washing is the best way to treat the denim fabrics.In addition, by comparing the experiment proves the feasibility of kapok as cowboy clothing material, and it has a great application prospect.