Sample proofing customers confirm that there are often color differences in large goods?

1
Rickety form

The color of the dyed fabric should be produced according to the color number or sample specified by the customer. However, in actual production, sometimes the color of the dyed finished product does not match the specified standard color and exceeds the allowable color difference standard. The color does not conform to the standard rickets is also a color difference rickets. However, the difference between the color difference and the above-mentioned color difference is that the former identifies the color difference rickets and does not necessarily compare the dyeing standards. When directly viewing the surface of the dyed product, it can be seen whether the color of the front, back, left and right, positive and negative colors are different on the same cloth. Color identification does not conform to the standard rickets identification must be compared to the staining standards, the color of the dyed cloth may be uniform, while the shade, color shade is different from the standard.


The expressions of color mismatched standards are:

(1) It does not conform to the same type of fabric (the same type of fabric refers to the same sample and the same tissue color sample as the original sample).

(2) Does not conform to the reference sample (reference sample refers to the color of different raw materials and different tissues).

(3) It does not conform to foreign samples (samples refer to fabrics, patterns, designated color samples, digital samples of the measurement and distribution system).

(4) Dissatisfied transaction sample (transaction sample refers to the sample provided by the domestic dyeing sample card and pattern, and the sample determined by both parties in the foreign trade transaction).


2
cause

(1) Dyeing prescriptions and improper process formulation. Before the dyeing product is put into production, it must be colored and sampled. However, in fact, the actual conditions of the sample and the dyeing production are not the same, and the color of the dyeing is generally different. Therefore, this requires the dyeing workers to understand and grasp the gap between the color matching and the actual production of the dyeing, and to correctly use the data and data obtained by the color matching sample to analyze and process it, and to formulate a more realistic and reasonable. Dyeing prescriptions and processes. If it is not properly mastered, it will be adjusted many times in the dyeing production, and the color of the dyed fabric produced by it will inevitably not match the standard.

(2) The color light source is not uniform. At present, most of the color-receiving light sources in printing and dyeing factories use natural light (north-facing daylight) and ordinary fluorescent lamps. The disadvantages of the above-mentioned light sources in color discrimination are:

a) natural light is susceptible to differences due to weather changes;

b) Ordinary fluorescent lamps are quite different from natural light, and the color is generally reddish. Therefore, the color effect of the same piece of dyed cloth viewed under different light sources is different. The dyeing standard and the dyed cloth are often different due to the dyed fiber raw material, the texture structure of the grey fabric, and the dyeing material used. The result is that the color is observed under a certain light source, and the two are basically similar, while the color is observed under another light source. The gap between the two is even larger.

For example, the light jade color and light orange color dyed in the evening are often reddish when viewed during the day, causing the color to be inconsistent with the standard, resulting in some color positions being “overwhelmed by the whole army” and having to be re-dyed; The dyeing of the fabric is two-color (the hue of the two kinds of cotton and polyester fibers are different), and the result is different under the ordinary fluorescent lamp and the color light of some colors obtained under the natural light during the day, and the dyed cloth does not conform to the standard.

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(3) The dyeing production plan is not well planned. The dyeing production plan is not arranged in the order of light to deep. When the color difference is large, there is no transition color arrangement, and the cleaning work during color change is not completed, so that the dye solution is stained, and the dyed color will not conform to the standard sample. .

(4) Dyes and additives are poorly managed in batches. Dyeing production requires a relatively high color shade for the dyes used. Any dye with a different color shade will cause the dyed fabric to be inconsistent with the standard. Dye mills in the manufacture of dyes, due to the differences in raw materials used, differences in texture, differences in the synthetic process routes, and the inconsistency of process conditions, resulting in dye shades of the same product name produced in different origins and factories. Differences. Even dyes of different production batches of the same origin, the same factory, and the same product name may have differences in shade. If the dyeing factory mixes the materials and uses them regardless of the place of production or batch, the dyed color must not conform to the standard. A similar situation exists for the auxiliaries.

(5) Dyeing process conditions and operation are not well mastered. The reason why the color does not conform to the standard for this reason is as follows:

a) The semi-finished products do not meet the requirements. If the dyed semi-finished product is insufficiently silky, the mercerized strip has alkali to change the color shade. After staining with a vulcanized element, the cloth is covered with red light instead of black.

b) Hard water for dyeing, dyes sensitive to hard water are prone to dyeing rickets. For example, direct pink 12B, direct fast blue RGL, etc., will become lighter in color, and will not conform to the color standard.

c) Inappropriate management of dyeing affects the dyeing effect. For example, the insoluble azo dye is dyed, and the fabric after the semi-finished primer is not immediately developed, and the shelf life is too long, so that the phenol on the primer fabric is decomposed by the influence of air, and the color is light.

d) The weighing of the dyeing material is wrong, the dosage is not accurate, and it is not found in time during the dyeing process, and the dyed color does not conform to the standard.

e) The process conditions must be strictly controlled during the dyeing process. If the process conditions are poorly controlled, such as temperature, humidity, concentration, pressure pH, speed and drying conditions are unstable, high and low, it will affect the color of the product.

3
Overcome

(1) To explore the law and sum up experience. It is necessary to pay attention to groping and summarizing the rules and experience between the color matching and the actual production of large samples, and strive to achieve a successful dyeing on the train. In order to ensure the rationality of the large production process, the following must be done:

a) The size of the fabric should be the same, and the process conditions of the semi-finished products should be consistent. It is advisable to use the same batch of semi-finished products.

b) The rolling mill with a small sample during padding should control a certain pressure. The pressure of the big rolling car and the small rolling car should be relatively fixed, and it should not be arbitrarily changed, so that the size is easy to obtain consistent. The bath ratio should be consistent when dip dyeing.

c) The crown, color, suffix and lot number of the dye used in the sample should be the same as the large production , as well as the additives used. The conditions for dyeing the sample are in line with the large sample.

d) When color matching, the main color dye should be relatively fixed, and the dye should be proofed by the variable adjustment color light to facilitate the uniformity of the size and color.

e) After the sample is tested, the influence of the affinity of the dye on the fiber and the adhesion force on the difference between the small sample and the large color are also considered. Since the small-scale padding is discontinuous, the residual dye solution is no longer reused, so the influence on the affinity is extremely small. The large-scale padding is continuous, and the groove dyeing liquid and the residual residue are continuously reused. If the affinity of the dye to the fiber is relatively large, such as indosin, vat dye leuco, direct, active, Naf Proper dyes, the dye concentration of the fabric taking away the groove dyeing liquid during padding will be greater than the dye concentration of the residual dyeing liquid in the groove. If the replenishing liquid is insufficient, the concentration of the groove dyeing liquid will be more and more light, and the fabric is The concentration of the dye that carries away the dye solution will also gradually decrease until the reduction in the concentration of the rolling solution is just balanced with the concentration of the replenishing solution, but this has caused a large difference in the color of the fabric.

Therefore, in actual production, the difference between the amount of each dye in the large sample and the small sample of the machine must be obtained according to the actual conditions of each machine, so as to calculate the use of the machine table and the process conditions. The percentage difference in dye usage only. The sample prescription plus (or minus) the percentage difference of the dye is a large sample. In this way, the dye concentration of the bathing solution can be balanced from the beginning to the end, and the color difference between the color matching sample and the large sample can be basically the same.

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(2) The dye is to be screened. For those dyes that are prone to discoloration during the dyeing process, dyes are generally not used. If it must be used, the corresponding measures must be taken to understand and master the performance of the dye. For example, when a soluble vat dye is used for dyeing a polyester-cotton blend fabric, the color change of the dye at high temperatures should be considered. Some dyes in acid dyes change color at a certain temperature, such as weakly acidic black GR, which changes color when the temperature is higher than 96 °C. For fabrics that require ironing fastness, after dyeing, high temperature hot drawing process is required. When color matching, dyes that do not change color at high temperature are considered. Otherwise, the dyes will change color and the color will not conform to the standard.

(3) It is necessary to adopt a standard light source that is suitable for daylight discrimination. The whole process of dyeing production color matching, large production and dyeing finished product inspection is carried out under a uniform simulated sunlight source, so as to greatly reduce the difficulty of color discrimination due to different light sources, and ensure that the color of the dyed product conforms to the standard sample. It is generally preferred to use a standard light source box, and a computer color measuring instrument can be used conditionally.

(4) It is necessary to arrange the dyeing production plan reasonably. In the small-batch, multi-color dyeing, in order to reduce the brakes, clean parking time and avoid the shortcomings of the cloth wrinkling frequently with the brakes, to improve production efficiency and avoid cross-color contamination caused by non-conformity For the purpose of the sample, it is necessary to divide the color positions that need to be produced in the near future into two categories: light medium color and deep variegated color. Each type arranges the production progress according to the chromatogram from shallow to deep. From red to yellow, it must be transitioned from orange. From yellow to blue, it must be transitioned from green. From blue to red, it must be transitioned from Qinglian. If there is no transitional color, it must be braked or cleaned, and cleaned. Dip-dyeing uses intermittent equipment, sometimes different color positions can be fixed relative to the machine to prevent chromatic aberration.

(5) Strengthen the management of the batch number of dyes and additives. Dyes of the same color and different origins shall be piled separately; the same color, the same manufacturer, and different batches of dyes shall be stacked separately. It is best to use the same batch of dyes for the same batch of cloth. In principle, do not use different batches of dyes to avoid the difference in color. The management of auxiliaries should also use the same management method as dyes.

(6) Strict process discipline. Grasp the three-level inspection of the craft on board (self-checking of the vehicle, workshop and factory inspection). Master the dyeing process conditions to ensure that the car is on the process. We must conscientiously grasp the sample and sample system of every worker in order to check and check, find out the problem in time, and ensure that the color of the dyed product meets the standard.


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