How to effectively control and reduce the dyeing color difference

In the printing and dyeing industry, the concept of continuous rolling dyeing chromatic aberration has a wide range of color difference, there are color difference between the samples, color difference between batches, bottom color difference, color difference between left and right, color difference within the batch and so on. This is the printing and dyeing workers have long encountered complex and difficult to solve quality problems. With the expansion of China's textile exports, participation in international competition is becoming more and more intense, the quality of the requirements are becoming more and more stringent. At present, the export of dyed products, the left and right color difference and the standard requirements of the color difference within the batch in 4-5 levels above, much higher than China's national standards. At the same time the color difference assessment, also by the traditional eyes rating to computer color measurement and identification. That is, by the traditional artisan skills up to science and technology, the color of the transmission began by the physical color wrench to the digital transition to the computer's color for the CMC, DE value control within 0-6, the batch of color difference is within 0-9. Moreover, the light source for color matching has also developed from ordinary office light D65, CWF, TL84, D75 to light source for color matching such as U3O, HORIZON, INCA, etc., and the color matching has increased from one lamp to two lamps, and three lamps for color matching respectively, while the requirement of color light remains unchanged. In order to meet the quality requirements of customers, improve the export competitiveness of enterprises, control, reduce or even overcome the dyeing color difference has become an important topic for printing and dyeing workers. In this paper, the author mainly focuses on how to control and reduce the color difference between left and right (commonly known as side color) and the color difference within the batch (commonly known as LOT color).

One, grasp the stability of raw materials, reliability, is the basis for controlling the color difference; dyeing products of raw materials, mainly refers to the blank cloth and dyeing materials, regardless of the batch size, before and after the requirement of raw materials quality is the same to ensure that to overcome the important conditions of the LOT color. Even if the objective quality of the raw materials are different, must also be done in mind, treatment is different, the LOT color is strictly controlled in the smallest amount of range.

Specifically, the following practices:

l, the same color number of blank cloth, the purchasing department is required to try to purchase the same cotton mill, the same batch of origin with the cotton blank cloth.

2, such as the intermediary for the blank, must be divided into different cotton mill products, such as two factories of the blank, the production needs to be put into production according to the batch number. If necessary, pretreatment and dyeing process materials to make appropriate adjustments to overcome the batch of products within the batch color difference.

3, for some special products, such as linen, linen cotton and other semi-bleached blanks, although pre-treatment, but the sensitive color is still difficult to control its LOT color changes. Control methods can be first in each bolt (volume) sampling l meters, do a good job of each bolt (volume) and the number of sample records, test dyeing the more sensitive colors. Then according to the results of the sample LOT color, each bolt (volume) batch production. Dyeing adjustments in batches, can reduce the production of LOT color.

4, where the same color number of products, raw materials changes (including the source of origin of blank fabrics, dyes, finishing agents) supply department must notify the technical department, sorting and stacking, strict comparative testing, in order to process, technically reasonable adjustments can not be changed to cope with the changes.

5, seven chemical material to adhere to the batch needs to be prepared in full, a color regardless of the size of the first request is the same origin, the same batch, the same color, concentration of dyes. It is best to use the full test method of dyes, and if you find any difference, you should use them separately and try the samples again to avoid LOT color due to the different color light and strength of dyes.

6, do not ignore the softener and other finishing agents on the color light, shade and edge color. A large batch of colors, in the soft finishing process, it is best to use the same batch of products - production on the same machine. At the same time, we also need to cut samples on the color tracking control, otherwise the batch of LOT color and edge color are difficult to control.

7, the correct choice of dyes, is another key to control the LOT color and edge color. Many companies receive customer samples handed over to the laboratory sampling, dye matching by sampling personnel to decide. The problem is that some sampling personnel, precisely the lack of practical experience in production. They only manage to align the small samples with the customer samples, and the dyeing on the dyeing rate is high or low, the color light changes quickly or slowly, the stability of the compatibility, different color samples of the same color and the size of the changes in the spectrum is difficult to grasp. Often small samples sent to the customer to confirm, to the production only to find the existence of the problem, and then go to change the dyestuff mixing, but also by the color light, the light changes in the constraints, it seems to be very passive. For this reason, we use the computer color matching, according to the usual selected dyestuff combination, select the DE value of the most ideal match, a type of six matches, and then send the dyeing supervisor according to the quality, stability (dyeing curve is generally the same), the principle of low cost selection of a group of matches, and then handed over to the test laboratory sampling, so that the sample not only meets the requirements of the customer, and to ensure that the color difference in the production can be controlled to the most stable.

8, the three primary colors although there are ten thousand variations, but the three primary colors are not omnipotent. Practice has proved that we can't rely on all three primary colors, in the face of any one color, the best way is to choose a similar color dye as the main color, according to the color light and then other dyes fine-tuning. At the same time, the matching of dyes should be adhered to the principle of less rather than more, the less the better.

Two, reform and strengthen the internal management of enterprises, is to reduce the color difference of the guarantee. The reason why printing and dyeing products are difficult to do, the reason why the printing and dyeing factory is operating difficult, is the production characteristics of printing and dyeing products. Dyeing and printing products from the blank cloth to the finished product often after more than 10 procedures. The production process combines chemical, physical, mechanical, environmental, human factors such as changes. more than 10 production links, any one link has a problem, will affect the quality of the final product. Therefore, continuous reform, strengthen the production management of printing and dyeing products is to control the reduction of color difference, to ensure product quality needs.

1, adhere to the technology-led production and operation management, is a feasible way to control the color difference: dyeing and printing plant traditional enterprise management, there are plans and technology, workshop and technology, technology and equipment, each in its own way of malpractice. It is unfavorable to highlight the position of process technology and product quality. A few years ago, we merged the technology and planning into the Ministry of Public Works, and the whole factory production was only led by one department of the Ministry of Public Works. At the same time, we reformed the management mode of production operation into a technology-oriented and quality-focused management mode. Under the premise of ensuring the small color difference, we specially design the pre-treatment process for difficult colors and varieties. Changed the previous multiple varieties of the same refining and bleaching process. Emphasize in the production operation management technology sings the main role, planning, workshop, equipment as a good supporting role. And the purchase of dyeing and chemical materials is under the control of the Ministry of Public Works. In the production process, whether it is the adjustment of the plan or the handling of the problem, whether it is the day shift or the night shift, the decision-making power, the right to command in the hands of the technical supervisor. This avoids the contradiction of pulling each other's strings and emphasizing production over quality, reflecting the role of "process as the core" to ensure quality.

2, strengthen the production operation in the field of technical management, is to reduce the color difference of the key: Given the characteristics of printing and dyeing products production, the vast majority of color difference or other quality problems are produced in the production operation. For a long time, printing and dyeing factory often mentioned "prevention first". But how to reflect in the actual operation? We think that the site monitoring of printing and dyeing plant, quality tracking, prevention and cure is the most practical "prevention-oriented", over the years, we attach great importance to the management of the production site. All production plans, process technicians, offices are located inside the production plant. Whether it is the manager of the Ministry of Public Works, workshop director, or refining and bleaching, roll dyeing, rolling dyeing, finishing the technical director and technicians, the focus of the daily work in the workshop site, the workshop (workshop) is the office. In this way, the technicians are able to know the operation of the products, the operation of the machines, the operation of the staff, and the change of the quality. At the same time, they are required to do "three to the scene" (when the machine is turned on, change varieties, stop for some reason must go to the scene), check the "four first" (take over the first piece of cloth, change varieties of the first piece of cloth, the first piece of cloth after clearing the machine, the first piece of cloth after the maintenance of the equipment), as well as seriously "grasp the triple" (the unification of technical operation, technology on board the inspection system, the quality of the next machine standardization), to the product operation of the process of boarding the "three degrees of "(temperature, speed, concentration) can maintain the correct and consistent before and after, so that the quality of each off-machine half-products can be stable and consistent, is the key to control and reduce the color difference.

3, the fulfillment of all levels of quality veto is to control the reduction of color difference guarantee: printing and dyeing production of the most fatal malpractice is the loose management, sloppy gatekeeper. Often a large number of quality problems before going to the root cause. Effective treatment of color difference, in addition to strict management, there is an urgent need for quality at all levels of serious and meticulous control. We fulfill the right to veto the quality of all levels, practice has proved to be another guarantee to reduce the color difference.

①The use of the department found that the difference in quality of raw materials, the right to order the return of its authority to replace.

②Technical staff of the state of the equipment to have a rigorous inspection system. Equipment problems found to affect product quality, the right to suspend production. Notify the equipment department to repair until it is complete.

③ Dyeing technology director of the pretreatment quality has the right to veto quality. Where found that the refining and bleaching half-products affect the quality of dyeing, the right to be obliged to rework to meet the standard.

④Quality inspection personnel of the dyed products in the edge color and LOT color inspection, less than the standard, have the right to return to the dyeing supervisor rework to meet the standard.

⑤Technical supervisors at all levels have the power of rewarding, punishing, adjusting and dismissing the employees under them for their operation level and performance. Where the position does not meet the technical requirements of the operation of the staff - are to adhere to the processing, proper placement.

6 customer is the "emperor", where customers require product repair due to quality problems, to accept unconditionally, no delay.

Three, seriously grasp the technical organization of each link measures to achieve the purpose of reducing the color difference: Dyeing edge color and LOT color, not only the dyeing process will produce. Side color and LOT color control, in addition to the management and raw materials involved in the enterprise, as well as technology, technology, equipment, operation and its control methods, etc. The whole process is intricate and complex. The whole process is intricate and complex, any one link of the error, will "touch a hair and move the whole body", and cause color difference.

1, pretreatment is the basis for the control of color difference: dyeing side color and LOT color, most people focus on the dyeing process to check the cause. And ignore the pretreatment of the basis for color difference. This one-sided tendency is obviously wrong. It can be said that: pre-treatment gross effect, whiteness of the same, the production of color difference has a pivotal role. Therefore, to achieve the purpose of controlling and reducing the color difference, it is necessary to spend effort to grasp the basis of the pre-treatment work.

1 ① desizing net cooking refining through: many enterprises due to the limitations of the equipment or planning and cost factors, often desizing cooking refining into one. But this desizing process, for some products with high pulp content (such as corduroy, Pakistan and India's blank fabrics), the gross effect is very unstable after boiling and bleaching. After exploring, we think: cotton fabric pretreatment can not ignore the importance of desizing. Desizing net can be boiled through, and only desizing net can give the pretreatment a stable prerequisite. In practice, we believe that: sewing head → desizing → burnishing → cooking and bleaching is the most ideal process design, dyeing products generally require more than 8cm of gross effect, left and right and before and after the fluctuations in gross effect should be controlled within 2cm.

② Rolling car rolling rate is consistent: pre-treatment rolling car rolling rate, whether to keep the front and back and left in the right rolling fluid is the printing and dyeing plant is easy to ignore the problem. Especially boiling bleaching and mercerizing rolling liquid rolling, such as rolling liquid rate is not stable, will inevitably cause dyeing color difference. Therefore, the pretreatment focus on the maintenance of the rolling mill to upgrade to the level of dyeing mill to deal with. Weekly rest days, the equipment department should focus on overhauling, the first shift every week, the technicians have to determine the rolling rate of the rolling car left and right, in line with the requirements to be put into production.

3 printing and dyeing production, it is difficult to avoid sudden electromechanical failure, which has a larger amount of cloth (600-800M) of the continuous decoction of bleaching machines have a greater impact. Occurrence of such problems, cooking and bleaching stopping time more than specified, each factory should be based on the actual development of rigorous rework measures, and the number of rework, box number accurate notification of the dyeing supervisor, in order to dyeing, respectively, samples put into production, to avoid the production of color difference.

④Adhereby adhere to the pretreatment quality inspection and clear handover standards. Appearance quality check of pre-treatment half-products is relatively simple. Inner quality inspection, such as gross efficiency, PH value, pulp rate inspection is not difficult. This article has been mentioned earlier, "the standardization of the quality of the next machine" must be persistent, serious implementation.