Reactive dyeing of cotton knitted fabric of differential cylinder control

Characteristics of pure cotton knitted fabric has decided they like woven fabrics of continuous dyeing, dyeing process is generally intermittent, that is, a cylinder, a cylinder production. Color difference resulting between the cylinder and cylinder (with the same recipe dye with a fabric) that cylinder differential is a persistent problem in dyeing and finishing industry. Factors affecting differential cylinder more, are rather complicated, fundamentally overcome cylinder problem impossible. However carefully analysed and controlled, the cylinder is possible within the scope of differences to a minimum. 1. quality control of grey cloth weaving quality stability is an important factor in producing cylinder differential. Natural fiber ingredients for cellulose fibers, water, natural impurity (ASH), these components will vary according to the natural environment, at the same time in the production process are also mixed with some debris, such as weaving finishes. In different raw yarn, or fabric production enterprises, these natural impurity doping not only differences in the content, and its physico-chemical properties are different, sometimes even the same yarn as raw materials, fabrics, there are also some differences on the dyeing property. Effective solution in addition to strict quality control of the weaving process, from raw cotton began to weave finish is, establishing a comprehensive traceability system for grey fabric and dyeing factory of weaving enterprise has the obligation to provide relevant data and information , to facilitate the dye factory distribution tank by reasonable or timely adjustment formula, and thus achieve the purpose of reducing cylinder differential. 2. quality control in production of semi-products due to the inconsistent quality of semi-products and cylinder differential of a considerable proportion. Semi-products quality 3 main factors: the capillary effect, pH value, whiteness. In the cylinder on the poor performance is due to thecapillary effect, cause fabric to dye dyeing ability of different because of different pH values, causing dye dyeing of different initial; due to differences in brightness, resulting in varying levels of color, crisp. So paying attention to the process before, unified pretreatment process parameters, precise control of additive dosage of each cylinder, before reunification process time, uniform dyeing machine of the operation parameters, to provide uniform stability for dyeing of semi-products, this is the important part of controlled differential cylinder. In addition, by raising the level of equipment, such as the actual realization of pretreatment and dyeing process on the device online detection (such as real-time precise detection of the pH value) and monitoring will provide an effective technical means for reducing cylinder differential. 3. the dyes and auxiliaries quality of dyes, additives on the stability of cylinder difference has a direct impact, on the selection and use of dyes, auxiliaries should note the following several points: a. batch quality and stability. Contrast dye color color difference is more than 4.5; batch of additive concentration difference in content between 0.5% per cent. B. choose excellent compatibility of dyes for dyeing of color combination. Good compatibility in several dyes combination dyeing rate of dyeing curve basically the same, different dyeing time periods only level without hue on shades of a color difference. C. low liquor ratio-dependent. Bath ratio dependence of meaning on the premise of dye amount unchanged, with bath ratio of increase or decrease, shade differences only in shades of different, and no apparent hue differences on. How to measure those complex or combination of the so-called quality of color dyes, such as some black reactive dyes. Experience shows that color shade shades of differences in the production control than to hue on the deviation control much easier. D. excellent reproducibility of dyes, goodreproducibility of dyestuffs cylinder differential will reduce the risk. E. fluctuations of pH value and dyeing and salt amount less wide adaptation range. As in the production process in the dye bath pH value of precise control and precise injection of salt and alkali additive, in the actual production process is difficult. In selecting these factors affect the small dye in dyeing process will better meet the needs of actual production. 4. poor process control the stability of cylinder is in control of other quality problems on the basis of a, such as flower color, color, and so on. Without these quality assurance, control of cylinder differential will lose its significance. Measuring technique is stable or not, dyeing success rate is the more critical to the quality of the pointer. Dyeing the success rate is above 90%, this process is a stable and mature process; in 80% per cent success rate, this process also needs to be improved; a success rate of less than 60%, this process there is a technical defect, needed improvement. A stable process should have the following characteristics: a. process operation of strong, in line with actual production conditions of the factory, workers action. When there are many tasks in the development process, often developed under laboratory conditions, no considerations or comprehensive enough to actual production conditions, so as to create practical difficulties. B. to have a certain amount of redundancy, mature and stable process not because of quality problems caused by a small mistake. Because the present conditions of dyeing and finishing industry production and the level of professionalism of workers, it is difficult to meet the operational requirements of too fine. C. dyeing of the same formula a success rate of more than 90%. 5. the general operation of the standard uniform dyeing factory process: tibetaners send send kind ¡ú laboratory sampling ¡ú confirm ¡ú confirm ¡ú color ¡ú plan cylinder production in dyeing workshop. Hereit should be noted is that tibetaners confirm color are generally considered to be the final color of the product, and sending the tibetaner the laboratory sampling colors shade more often than not the final product. Because we are not able to completely mimic the process of finishing and finishing and processing on the condition of some of the technology fabric shade of color have a greater impact, such as amplitude and shape drawing machine type of temperature , use softener (cationic softening agent, organic silicon softening agent can cause larger shade changes). This is caused when dyeing workshop production of the color standard according to tibetaner’s end-product requirements operation, shade and the actual end product and the tibetaner requires the existence of large deviations. Therefore, require laboratory shade dyeing stages of standards should be provided for dyeing workshop. When a tibetaner is the same color product production time interval is long, laboratories should be complex samples (that is, proof), found a large deviation correction in a timely manner. 6. production of shade when deviations within the scope of control in the client allows the e, production should be a unified control + e, or-e in deviation ¡À e If both (mutually complementary coloured light deviation), most likely due to cylinder differential is too large and was rejected by the tibetaner , while e is still within the range of tibetaner requirements. In addition, dyeingProduction of color standards is to ensure uniformity and uniqueness. There are multiple standards coexist, who really controlled differential cylinder extremely unfavorable. Because sample standard will change with time and space and have some changes, so the color sample update necessary. With the development of computer technology, the use of computers for digital management of colour difference, which can effectively solve the above problem, this is one of the enterprise development direction of modern management. 7. the right shade and color mixing methods as standard deviation and color blending in the machine is in the process of dyeing operations frequently. The factory by used of toners method the does not same, but a common of principles is: Dang shade has partial red, and partial deep Shi, should be used SOAP wash Hou toners method, because experience indicates that, red reactive dyes at any time between of extended will has a continued of Shang dye process , shade performance Shang will increasingly red; Dang shade partial yellow or partial blue Shi, should be used “half feet water” toners method, this species way will more shortcut effective; Dang shade overall partial shallow Shi, should be used by proportion “full feet water” Commission addition. 8. correct reasonable cylinder cylinder distribution methods are also effective methods to reduce cylinder differential, in principle, the same color equipped cylinder number of the less the better. When a color distribution in 2 tanks and more than 2-cylinder, the cylinder number, first the 1th cylinders, as in the original process implementation, such as the 1th cylinder does not match the shade, after adjusting the formula, then 2nd tank in dyeing; and then the 1th cylinder press 2nd tank shade for color handling, later dyed were conducted by the 2nd formula. Course in distribution cylinder number only when they are 2-cylinder, can also stain, and color mixing process at. Worthy of note is, 1th cylinder distribution of cylinder capacity should be as small as possible, after all color matching in the dyeing process is risky course of action, should, in principle, within the scope of the risk to a minimum. In addition, within the same dye dyeing of the same color, consistent volume of capacity at a time as possible, for reducing differential cylinder has a larger benefit. 9. equipment and operation of the stability of dyeing machines have a dyeing tank type is one of the important factors of the difference.In the plan when the cylinder, as far as possible be the same species within the same color in dyeing machine of the same type of production, to a great extent reduce the generation of cylinder differential. This, of course subject to actual production conditions of dyeing factory. If you can do operators of fixed, the so-called three-fixed (fixed personnel, fixed machines, fixed process) that will be more conducive to the operatives the accumulation of experience, will naturally reduce the number of actions at the same time human error. 10. staff professional qualities of poor site management experience will undoubtedly reduce staining cylinder is important that all dyeing factory there is a consensus, so key personnel in key positions of high professional quality requirements, should have the operational capacity of the combination of theory and practice. In short, cylinder differential factors are, the control is a complex process, simply return it to technology or management factors are objective enough. How to control, each factory has its own set of experiences. In the actual production, only under the joint efforts of the relevant technical and management personnel, cylinder differential incidence will be reduced. (AB group/Zhang Xiuqiang, Jiangsu)