English Views: 49 Author: Site Editor Publish Time: 2021-11-03 Origin: Site
The classification and causes of common defects in dyeing and finishing production are introduced, and color unevenness (color flowers, color spots, stains), color fastness, and fiber are analyzed from the aspects of color quality, internal quality and other quality aspects. Damage, lack of elasticity, oblique warp and weft, thin and dense roads, shrinkage rate, gram quality and door width, as well as the causes of dyeing and finishing defects such as stains, pilling, crepe printing, and substandard finishing.
In summary: the spinning and weaving process should be strictly controlled to avoid dyeing and finishing defects caused by different batch numbers of yarns; at the same time, suitable dyes and dyeing and finishing aids should be selected for different fibers and different types of textiles. Reagents and dyeing equipment, carry out the appropriate process, reduce the number of repairs, and avoid the occurrence of dyeing and finishing defects.
In the dyeing and finishing of textiles, due to the many front and back links, there are many factors that affect the results of the dyeing and finishing. In addition to the more frequently occurring color quality, such as color difference defects. There are often other quality problems. Dyeing and finishing defects can be basically divided into the following three categories according to the phenomenon:
a. In terms of color quality: color difference, color unevenness (coloring, color spots, stains) and color fastness and other issues.
b. Intrinsic quality: fiber damage, lack of elasticity, warp and weft skew, thin and dense road, shrinkage rate, gram quality and door width.
c. Other quality aspects: finishing agent stains, pilling, crepe printing, crepe strips and substandard finishing.
1. Yarn (silk) and grey fabric quality
Both the quality of yarn (silk) and grey cloth affect the quality of dyed finished products, and this influence has a certain degree of latentity and is often exposed after dyeing.
And this effect is often overlapped with the problems in the dyeing and finishing process, which increases the complexity of dyeing and finishing. It also makes it more difficult to find the cause of the defect. Some dyeing and finishing defects caused by yarn (silk) and grey fabric quality problems, such as width of the door width, warp and weft skew, and expansion rate, can be adjusted slightly in the finishing process, but they cannot Solve the problem fundamentally. Therefore, the source of raw materials should be strictly controlled to ensure that the quality of yarn (silk) and grey cloth meets the indicators, and to avoid the appearance of defects in subsequent dyeing and finishing.
2. Dyeing and finishing process
The quality of the dyeing finishing process is affected by both hardware and software.
In terms of hardware: first is the applicability and integrity of hardware such as mechanical equipment, instruments and instruments; second is the inspection and selection of the quality of raw materials such as dyes and auxiliaries.
Software aspect: It is mainly reflected in the implementation options such as process prescriptions, production processes, operating procedures, etc.; in addition, it is also reflected in the management level (including technical management, discipline management) and the overall quality of the grassroots employees. First of all, we must have a clear understanding of the variety adaptability of dyeing and finishing equipment, because dyeing and finishing machinery has differentiation and specificity for different fibers and different types of textiles. It is necessary to understand the fibers that dyeing and finishing machinery can add and adapt to woven fabrics. Or knitted fabrics, if suitable for knitted fabrics. It is also necessary to distinguish whether it is suitable for warp knitted fabrics, weft knitted fabrics or flat knitted fabrics; it should also be understood whether the equipment is limited to a single type or a composite type that can be used for several types of varieties.
For example: A. High-speed and high-pressure jet dyeing machine is suitable for dyeing polyester warp knitted fabrics, and also suitable for dyeing polyester filaments for medium-thick wool-like style woven grey fabrics; but it is not suitable for low-density thin polyester filaments The dyeing of woven fabrics (such as rain yarn, terylene and other silks) is also not suitable for the dyeing of polyester-viscose, polyester-cotton and other blended fabrics and weft knitted fabrics. Otherwise, cracks (filament low-density thin woven fabrics) or pilling (polyester viscose, polyester-cotton blended fiber fabrics) or the original elastic characteristics of the fabric will be lost (weft knitted fabrics) after dyeing. ).
B. The jigger is suitable for the dyeing of woven fabrics with a wide range of light, heavy and thin in small batches and multiple varieties. But it cannot be used for knitted fabrics with a loop structure.
C. The overflow dyeing machine is suitable for weft knitted fabrics, polyester-viscose, polyester-cotton blended fibers and knitted fabrics with high elasticity requirements, but not suitable for the dyeing of warp-knitted and woven fabrics. Silk woven fabrics should be dyed on a jig dyeing machine, but crepe fabrics and real silk knitted silk fabrics that are both woven with real silk should be dyed on a specially designed machine that is significantly different from the overflow dyeing machine used for cotton. Secondly, different dyes are suitable for different fibers, and the suitable dark, medium and light colors are also different. Therefore, it is necessary to distinguish between different types of dyes. For example, the S type in disperse dyes is suitable for deep and dense color dyeing. E-type dyes are suitable for medium and light color dyeing; BES type of B-type reactive dyes is suitable for medium and light color dyeing, and B-D type is suitable for deep and thick color dyeing. Due to the different types of fibers and fabrics discussed above, the different dyes, and the different dyeing and finishing machinery and equipment, the auxiliaries selected will also be different.
For example: half-filled jet dyeing machines, liquid flow dyeing machines, etc. require the use of defoamers; and full-filled jet dyeing machines, non-nozzle overflow dyeing machines, jigsaw dyeing machines, rope dyeing machines, etc. No defoamer is needed. For example, silicone oil softeners are widely used in the soft finishing of fabrics and garments. But for the dyeing of loose fibers, single yarn bobbins and hank yarns, which are the same cotton fibers, the use of silicone oil softeners can easily have a negative effect on spinnability and weaveability; and it is usually used in fabric finishing. Unlike the padding car, the finishing of this type of softener can only be done in the dyeing machine.
In short, we should fully understand and recognize the differences in raw materials, equipment, dyes, and auxiliaries, and improve the quality and level of users in order to ensure the dyeing and finishing quality of textiles. Avoid blemishes.
1. Uneven color
The uneven color is mainly colored flowers, color spots and stains. Among them, the problem of color flowers is more likely to occur in rope dip dyeing. The selection of additives and the order of heating and feeding should be properly controlled; in tight open-width dyeing Although there is less chance of color problems, it is necessary to use leveling agents to prevent color spots and stains mainly related to the cleaning of dyes, auxiliaries and equipment. For example, some disperse dyes with low water solubility are affected by particle size, Anti-agglomeration performance, process recipes and whether the dyeing machine is cleaned thoroughly or not are affected by factors such as improper control when used. It is prone to problems of color spots and stains.
2. Color fastness
There are many items of color fastness, mainly including: soaping fastness, rubbing fastness, light fastness, perspiration fastness, chlorine fastness and weather fastness, etc. Among them, soaping fastness is mainly determined by subjective Causes; light fastness, perspiration fastness and chlorine fastness are mainly affected by objective factors, namely the nature of the dye. The rubbing fastness and weather fastness are not only related to subjective factors, but also affected by objective factors (such as the types of dyes and additives). Caused by uneven color. It mainly occurs on cotton fabrics, especially after using reactive dyes containing vinylsulfone groups; and the windmark phenomenon will not appear immediately after the fabric is dyed. The wind printing problem does not appear until the warehouse or even after the garment is finished. Generally speaking, if the fabric is not cleaned after dyeing, there is more floating color, the cloth surface is alkali, and it is not dried in time after dyeing, or it is stored in a wet or semi-wet state. After a long time, the parts exposed to the air are prone to wind printing, and this phenomenon is more obvious when the CO content in the air is higher. Due to the different uses of textiles, such as clothing, shoes and hats, bedding, curtains As well as industrial fabrics, their respective requirements for color fastness are different. Therefore, the appropriate dye variety should be selected according to the use of each textile. The color difference is not discussed here.
1. Fiber damage
Fiber fragility is directly related to the out-of-control of the pre-treatment, and it is also related to the excessive number of peeling and re-dyeing. It will cause a sharp drop in fiber strength. Severe fiber fragility will form holes in the fabric, and slightly in the garment. Needles appear. Therefore, the pre-treatment process and the number of repairs should be strictly controlled.
2. Lack of flexibility
For non-spandex weft knitted fabrics, the elasticity is formed by the combination of the weaving method (such as ribbed cloth) and the elasticity of the fiber material itself, such as stretched yarn. If the dyeing and finishing equipment is not selected properly. For example, put this kind of fabric on the nozzle pressure above 1 kg/cmz. Dyeing in a high-speed jet dyeing machine with a running speed of 400-600 m/min will expand the diameter of the fabric tube. Decrease in elasticity. If the dyeing defect occurs, then peel off the color and repair it. The elasticity will be further reduced. For fabrics with spandex participation. It is also necessary to reduce the number of repairs. The more the repairs, the more the elasticity of the fabric will decrease. In severe cases, the spandex yarn will even be broken and the final wearability will be affected.
3. Longitude and weft oblique
Woven fabrics and knitted fabrics are prone to weft skew, which is caused by equipment and operation. Weft knitted fabrics are prone to warp skew, also called wale skew. This problem is mainly caused by the direction of skew caused by weaving. The degree of harmony is affected by the twist and twist direction of the yarn count, the length of the loop and the number of loop forming systems, and the direction of rotation of the loom. Ill Although this can be corrected to a certain extent during the tentering process in the finishing process, this For all-cotton weft knitted fabrics, it is temporary, and the skew tends to return to the original position after the garment is washed, so preventive work should be done in the weaving link.
4. Shrinkage rate, gram quality and door width
Dyeing product shrinkage rate, gram quality and door width are related to each other and influence each other. In order to achieve the stability of these indicators, we should strictly control the weaving of the grey fabric. Secondly, standardize the operation in the dyeing and finishing process if the rough fabric is in the weaving process. If the control is not in place, the above indicators cannot be reached. Although some compensation and adjustment can be made in the dyeing and finishing process, it can only be a limited correction within a certain range and cannot be corrected.
5. Via willows, rungs and sparsely dense roads
Warp willows and crosspieces can occur on woven fabrics and knitted fabrics. From the appearance point of view (such as rain-like stripes, horizontal stripes and color stripes, etc.), it is a problem of color quality. However, the main reason for this step is not because the company failed to manage the production plan, and the fiber raw material management is chaotic. This type of problem caused by the mixed weaving of fibers of different batches and batches is not obvious on the white blank, so it is easy to be ignored. Although dyes with good hiding properties are selected during dyeing, such problems can be controlled to a certain extent, but they cannot be fundamentally controlled. The above problem is solved. Generally speaking, it is best to arrange the production of white fabrics with such problems, followed by the production of black or printed fabrics. The dense road means that after the fabric is dyed, the surface of the fabric presents a phenomenon such as optical illusion properties.
Similarly, the problem of thin and dense roads is not easy to be found in the white blank and is often ignored. The thin and dense roads appear because the knitting needle position has loosened after the knitting machine has been used for a long time. Arrangement is irregular; woven fabrics may be caused by the abnormal beating-up device of the loom. These problems are generally caused by the lack of technical quality of the loom maintenance work, and the lack of management responsibility and inadequate management.
Therefore, it is necessary to improve the quality level of grassroots employees, strengthen the supervision of managers, and avoid the appearance of such defects.
1. Finishing agent stains
There are many types of finishing, and their importance and influence on textiles is no less than that of the dyeing finishing process. Finishing defects will inevitably appear. In the process design, in order to shorten the production process, save time, and be soft, antistatic, and waterproof. Oil-proof finishing is often carried out together. However, due to the compatibility problems of various additives, it is more likely to cause the appearance of spots, stains and other defects of the finishing agent. In addition, some finishing defects are irreparable for textiles with multi-color yarns and multi-color cloths, such as the use of silicone oil softeners to dye cotton fiber loose fibers, single yarn bobbins and hank yarns. Finishing is often carried out in a dyeing machine. After a long period of continuous use, such softeners will form agglomerations on the inner wall of the processing equipment and its pipes. After a certain degree, the accumulation may suddenly fall on the fibers and cause silicone oil stains, while the fiber silicone oil It is very difficult to remove stains; in addition, people require durability of the effects of finishing aids. But the better the durability, the more difficult it is to repair and remove. For example, silicone softeners, fluorine-based three-prevention finishing agents, coating agents, etc. are all varieties with excellent durability and difficult to remove. Therefore, in the use of such reagents, repairs should be avoided as much as possible, and the use process should be meticulous and standardized.
2. Pilling
Pilling is prone to occur for unmercerized polyester-cotton blended, polyester-viscose blended and polyester-acrylic blended fabrics. As described in 1.2, improper selection of dyeing machines is one of the reasons for this type of dyeing and finishing. one.
3. Crepe printed crepe strips
Large-area wrinkle printing is one of the problems caused by loose dip dyeing. The root cause is mainly caused by the dyeing form of the dyeing machine and its equipment characteristics. Anti-wrinkle additives are beneficial to avoid the appearance of wrinkles in the liquid jet dyeing machine. The difference in the shrinkage rate of the fabric in the dyeing bath caused by the grey fabric yarn and fabric texture will also cause the appearance of wrinkle marks. The straight wrinkle strips are mainly caused by the tight open-width dyeing equipment system without control and prevention. Therefore, the process should be strictly controlled.
4. Substandard finishing
Functional finishing such as soft, waterproof and antistatic, etc. If the functional index is not reached, re-finish it again. However, for the saturation point of the functional index of some finishing auxiliaries, an experimental appraisal should be made, otherwise the finishing effect shall be repeated Not big.
There are many factors that affect the quality of dyeing and finishing. There are factors such as fibers, grey fabrics, dyes and auxiliaries, as well as the matching of textile varieties and equipment; it also includes all aspects of technology, technology, management and the quality of grassroots employees. factor.
Therefore, repairs in dyeing and finishing production cannot be completely avoided; repairing is also an indispensable technology in dyeing and finishing production. However, once certain defects occur, they cannot be repaired and returned to normal. Especially some hard damages such as fiber brittleness, holes, cracks in the fabric structure, pilling, etc.; other types of textiles such as multi-color yarn, multi-color yarn-dyed, yarn-dyed and printed varieties . For non-brilliance flaws that can be stripped and re-dye repaired, such as finishing agent stains, discoloration, coloring, staining, etc., it is not suitable for repairing certain textile and weaving flaws; Such as too serious warp willows, cross bars, sparse and dense roads, gram quality, and door widths.
It is generally difficult to fundamentally correct in the dyeing and finishing process. Therefore, in the production process, where all possible problems may occur, a comprehensive prevention-oriented strategy should be adopted in a timely manner, so as to be proactive and truly effective in reducing and avoiding dyeing and finishing production. Qualitative issues in the process.
