棉织物过度氧化引起破洞的检测方法

Detection method of holes caused by excessive oxidation of cotton fabrics

棉织物在氧漂工序中容易出现破洞现象,为了查清破洞产生的原因,本文将不同破洞的棉织物放入20 mL硫代硫酸银络合物测试溶液中煮沸2 min,用去离子水冲洗后观察破洞周围的颜色变化。结果表明,由机械等外力造成的破洞,破洞口与布面颜色一致;因局部过度氧化引起的破洞,破洞口颜色比布面颜色深。通过X射线衍射仪、扫描电镜和X射线光电子能谱仪对其进行表征,得出棉织物经测试溶液检测后,表面有银析出,颜色深的洞口含银量比其他部位多,表明这类棉织物破洞是因为局部过度氧化造成的。

In recent years,cotton fabrics,especially summer clothing,have been increasingly favored by young people in domestic market for their mercerization,moisture absorption,breathability and soft touch,and the market potential demanding for cotton cloth has been huge.Under the requirement of energy saving and emission reduction for high energy-consumption printing and dyeing enterprises by the Chinese government,most dyeing plants have adopted the more efficient short process of one-bath one-step cold pad-batch for cotton cloth bleaching.The hydrogen peroxide added in this process is over three times more than that of the traditional process.After oxygen bleaching mercerization of the cotton cloth,local excessive oxidation occurs and oxygen bleaching holes are more likely to occur.In the production process of cotton cloth,the selection process of different cotton cloth specifications is different,resulting in complex reasons for holes.Therefore,it is necessary to find out the causes of holes in the production process and formulate corresponding preventive measures and technological processes.In this experiment,aldehyde cellulose produced by bleaching cotton cloth with hydrogen peroxide was oxidized by a self-made weak oxidation reagent,so that metal silver atoms could be directly precipitated on the cloth surface.According to the number of silver atoms precipitated from the cloth surface and the hole opening,the color depth was formed,the intensity of hydrogen peroxide decomposition was judged,and whether the hole on cotton cloth was caused by excessive oxidation was proved from the side.Then,1 mL of 8%silver nitrate solution,and 2 mL of mixed solution of 20%sodium bicarbonate and 20%caustic soda were added into 17 mL of deionized water.Then,the mixed solution was shaken up quickly.Subsequently,5g of cloth with holes was boiled in the solution for 2 min under 100℃,and then it was washed with deionized water.The color difference around the hole of that fabric was observed.The cotton cloth with holes were characterized by Fourier transform infrared spectroscopy,X-ray diffraction,scanning electron microscope(SEM)and X-ray photoelectron spectroscopy.The test results of the self-made solution show that the holes caused by mechanical and other external forces have the same color as the holes on the cloth surface,indicating that the silver content precipitated is basically the same.As for holes caused by local overoxidation,the color of the opening is darker than the cloth surface,and the silver content of the hole area is obviously higher than that of other parts.During the test,it is found that the decomposition rate of hydrogen peroxide is affected by temperatures,pH values and metal ions,and the symbionts and textile auxiliaries in gray cloth can inhibit the decomposition of hydrogen peroxide.Fourier transform infrared spectroscopy shows that the structure of most cotton fiber polysaccharides changes into dialdehyde cellulose after oxygen bleaching.After treatment with the self-made hole breaking detection reagent,the aldehyde group and silver ions have oxidation-reduction reaction,and the aldehyde group disappears.Through characterizing the cotton cloth tested by the self-made hole detection reagent,it is concluded that the black particulate matters on the cotton cloth surface are silver atoms.The hole areas such as burnt holes,hook holes,weak yarn strength holes and damp mildew holes are of the same shade as the cloth surface.Nevertheless,compared with the main elements of the cloth surface,there are more black silver atoms in the hole than in other places,which makes the color darker than in other places.As the demand for oxygen bleached mercerized cotton cloth is gradually increasing in domestic market,it is significant to determine the causes of holes for production prevention,which will be beneficial to cost saving and energy conservation and emission reduction.For the cotton cloth with holes during the production process,the semi-finished cotton cloth can be treated through lower tension process on the machines,increase the friction between yarns by adding adhesives,or even be changed to the overflow or air cylinder with low tension for dyeing,so as to reduce the probability of holes as much as possible and minimize the loss.In the future,the weaving mill will equip the magnetic metal cloth inspection machine in the gray cloth inspection.As long as the fabric has more than a certain amount of metal ions,the metal alarm device on the cloth inspection machine will raise the alarm to prevent the problematic gray cloth flowing into the next process,which guarantees the good quality.