Discussion on the technique of color light sample of exhaust dyeing process

Abstract : This paper systematically elaborates the accuracy and stability of the color light pattern of the exhaust dyeing process. From the three aspects of playing sample, enlarging sample, and mass production, we analyzed the factors affecting shade, and put forward operational considerations in combination with practice.

The requirements for the shade and color of dyed fabrics for export clothing are increasingly demanding. Therefore, how to improve the accuracy and stability of the color shade of the exported dyeing cloth and adapt to the customer's requirements becomes more and more important. It not only relates to the economic benefits of the company, but also relates to the company's reputation. Therefore, some people called the color of the symbol accuracy and stability, called the soul of the dye. The author discusses how to improve the accuracy and stability of the color light sample in the dyeing and dyeing process, and discusses some practical experiences.
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1 proofing dithering

1.1 First of all, the new color sheet issued by the business plan department must be carefully reviewed. Among them, the standard sample should be complete, the light source must be clear, the fabric organization specification should be clear, the color fastness requirements (soaping, friction, sun exposure, chlorine resistance, dry cleaning, etc.) and finishing requirements (soft, waterproof, antibacterial, flame retardant , UV protection, etc.) To be precise, the sample delivery time should be reasonable. When problems are discovered, it is necessary to have a unified understanding with the business planning department.

1.2 Before proofing, it is necessary to jointly determine the quality of the semi-finished products with the production planning department. Such as mercerized cloth is not mercerized cloth; grinding cloth or unsmoothed cloth; the white cloth or bleached cloth; pre-shaped cloth or post-shaped cloth; pre-shrinking water cloth or shrink cloth. The principle is that the cloth used for proofing must be consistent with the large-scale production cloth in the future, in order to unify the technological process and technological conditions, and should not be changed on the way.

1.3 Before the proofing, the production plan shall be unified with the production planning department. If the production is liquid jet dyeing, or flat cylinder dyeing dyeing, once determined, it should not be changed on the way. Because of the different proofing conditions for liquid dyeing and jelly dyeing, the dyes and auxiliaries used are also different. If you change, you can only re-proof the sample. The prescription for the proofing must not be used in combination.

1.4 According to the customer's color list, the dyeing depth, color brightness and color fastness are required. If dyeing deep dark color, use high-strength, high deep-deep, high-humidity fastness dyes; dyeing light-colored color, use high levelness, high light fastness dye; if the chlorine fastness If it is required, chlorine-resistant dyes should be selected; for the fastness to dry cleaning, dyes that are resistant to organic solvents should be used; when dyeing cotton/cotton/cotton/polyester fabrics, especially when dyeing white or flashing colors, they must be selected. Small stained dyes. In the case of nylon-cotton-cotton-cotton-stretch fabrics, when dyeing nylon, disperse dyes should be used together with neutral dyes or acid dyes to ensure vividness, color fastness, and uniform fabric surface to meet customer requirements. It should be pointed out here that nylon and spandex have great differences in the color-receiving properties (darkness, shade) of disperse dyes. Disperse dyes alone dye nylon, but its level dyeing is good, but spandex is often produced in the cloth Silk" jumps out, affecting the uniformity and color of the fabric.

1.5 Before the approval of the sample, the original sample provided by the customer must be reconsidered. The original samples provided by customers usually have the following situations:

(1) The original organization specifications are different from the organization specifications specified by the order

In this case, the light absorption, reflection, and transmission of the fabric are often different, making it difficult to match the sample with the original sample light. At this point, you should play a few different shades of different shades for customers to choose, so as to improve the customer's acceptance rate.

(2) The original sample is not a fabric but printed cardboard

In this case, because the surface of the paper sample is smooth and has a strong luster, and the pattern is a printed coating, not a dye, etc., the colored light of the dyed sample is generally difficult to match with the original sample under the irradiating light source. At this time, only a few different shades of different shades can be selected for customers to choose.

(3) When dyeing cotton brocade or cotton/polyester blend fabrics, if the original samples provided by the customer, the color shade of the bicomponent fibers is poor and the homochromaticity of the color light is poor. At this point, there are usually two cases: First, it is necessary to retain this two-color effect; Second, do not double-color effect, but to uniform color. Therefore, the color depth of the bicomponent fibers should be flattened (due to the poor dyeing property of the bicomponent fibers in the original sample). In this case, be sure to ask the customer clearly so that the sample is not confirmed.

(4) The original sample is under a light source with a certain amount of fluorescence

In this case, pay special attention. Generally, there are two possibilities: first, the fabric should have a fluorescent effect under a specific light source; second, the fabric itself does not require fluorescence, but when dyeing, an optical brightener is added for the sake of brightening. . At this point, we must first understand the customer's real requirements, and then, according to the requirements of the approval.

(5) The original sample is a silk fabric or an acrylic fabric (or acrylic yarn), but the sample must be made of pure cotton, cotton, or cotton.
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In this case, the original sample is often dyed with an acid dye or a cationic dye, and the vividness is particularly good, so that the sample cannot reach the brightness requirement of the original sample. In this case, you must first try to get a similar sample for the customer's reference and explain the reason to the customer. If fluorescent brighteners are added to brighten, customer consent must be obtained.

(6) In the customer's color list, often with "white" color number, such as: natural white, ivory white and pearl white, but no physical standard sample. In this case, it is necessary to clarify the so-called “shade” in the color list in advance, which means white, bleached or whitened. If the customer is confused about this, it is difficult to identify the three types of whitening, bleaching, and whitening to be recognized by the customer. If the product is identified as a whitening sample, three kinds of samples of yellow, red, and blue light are generally provided. , Let the customer confirm. For this kind of situation, we must take it seriously. Otherwise, when it comes to acceptance of large cargoes, it is easy to disagree with customers and even rework.

(7) For cotton, cotton, polyester, viscose, polyester-viscose and other blended fabrics or blended fabrics, the original samples provided by customers are sometimes flash-colored (ie, the two fiber components have different colors with a flash effect). For flash color samples, it must be determined exactly what kind of fiber is what color, generally cannot be changed. If the colors are reversed, there are generally two situations: First, the overall effect of the cloth is mostly inconsistent; second, if the proportion of blending is similar and the weaving specifications are appropriate, the overall effect of the cloth surface is basically similar, giving people the illusion. However, the potential problem is that the customer will refuse to receive the goods once they have noticed that the fibers are miscolored and must be re-stained. Therefore, the flash color should be particularly serious and not sloppy.

(8) Nylon and polyester contained in cotton/cotton/cotton fabrics are not all matt and sometimes light. The strength of nylon and polyester luster has a great influence on the brightness and brilliance of the dyed shade of fabric. Therefore, it must be determined whether the nylon or polyester contained in the original sample provided by the customer is glossy or matt. If there is light, the same fabric should be used for proofing. If the fabric is dyed with a light-free fabric, the shade of light must be inconsistent. Such as brightening with fluorescent brightener, usually customers do not receive. Therefore, you must obtain customer approval in advance and you must not make your own claim.

(9) The nylon component in the cotton-knitted fabric, usually nylon 6, but also nylon 66. Because nylon 6 has more than double the amino group content than nylon 66, nylon 6 has a high affinity for anionic dyes, good dyeing depth, and easy to dye darker shades. Nylon 66, due to its low amino content, is only suitable for dyeing in light shades. Therefore, before proofing, first, try to ask the weaving factory about the type of nylon. Second, try to dye deep shades with nylon 6. If nylon 66 is used to dye deep shades, even with acid baths and ultra-high temperature (100°C) saturated dyeing, depth requirements are often difficult to achieve. Even if the sample reaches the depth, the reproducibility of the sample is often poor, and there is also the problem of low color fastness and serious sewage.

(10) Twill fabrics with positive and negative sides are generally faceted with twills. There are exceptions and negatives are positive. Therefore, the original samples provided by customers should be carefully examined. If you find that the swatches in the color sheet are facing up, be sure to find out whether the opposite is a positive color or whether the customer is affixing a swatch. It must not be empiricism and be changed without authorization. Otherwise, sample replay is a trivial matter. If it is put into production, it will cast a big mistake.

(11) Sometimes the color sheets provided by customers include both the original samples (usually different from the required texture in the color sheets) and the approved samples (usually the first approved samples that are commissioned by other factories, and their textures are general and color The requirements in the singles are the same), but there is usually a certain shade or depth difference between the two. At this point, the customer's request generally has two kinds: one is based on the original sample as a standard, re-approved sample; the other is to provide the first approved sample as a standard, re-proofing. In this regard, it is important to understand the intent of the customer and not subjectively judged.

1.6 There are clear light source requirements, such as natural light, daylight lighting, D65 light (artificial daylight), TL84 light (white light in European department stores), CWF light (white light in American department stores). F/A light (indoor tungsten light), UV light (ultraviolet light), etc. In the actual work of the factory, there are the following problems:

1.6.1 Standard Light Box

(1) The standard light box and the lamp used have more brands. Different brands of light boxes and lamps have certain differences in color shades.

(2) Improper use of the standard light box. For example, on a gray floor of a light box, a color card type card is placed, and even on the gray inner wall of the light box, a prescription paper and a color model board are attached, which will cause a certain influence on the color light, and thus appear when the standard light box is matched. The shade of light in the factory light box matches, but the color light deviation in the customer company's light box causes the approval of the sample and the large color light to be difficult.
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Therefore, the standard light box, especially the lamp, must use products that meet international standards, and use the lamp to be correct, so as to eliminate the standard light box caused by the non-standard light source and improper use of the light box, resulting in color difference.

1.6.2 D65 light source

The D65 light source is an artificial daylight source. Compared with natural light sources, their response to colored light is not exactly the same. Some customers confuse the two and think that D65 light is natural light. Therefore, the proof color sheet is often specified as a D65 color match, and when a small sample (or large sample) is accepted, natural light is used for color matching. Therefore, disagreement often occurs between a factory and a customer. In this regard, it is necessary to communicate with customers, make a unified understanding, and eliminate misunderstandings.

1.6.3 Different Light Sources

Some customers require two different light sources for color matching, and even require two light sources to be turned on at the same time, using a hybrid light source for color matching. In this case, it is usually necessary to produce obvious jumping lights. That is, under different light sources, different shades of light are produced, even if it is not. 

Different dyes have different structures and have different light absorption and reflection properties for different light sources. It is not easy to solve the problem of jump lights for fight color dyes (2 to 3 only fight). The only way to do dye compatibility test is to use dyes that are compatible with the light source. Such as active red M-3BE, active yellow M-3RE, active black KN-B combination, DyStar's active red 3BS, active yellow 3RS, active blue FBN combination, active red B-2BFN, active yellow B-4RFN, Reactive black KN-B combination, etc., under different light sources, the degree of jumping lights is relatively small. The reactive black KN-G2RC, reactive black N and other mixed dyes, generally jumping lights serious, should pay attention when using.

1.6.4 Color Lights

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