Open-width dyeing and finishing processing has unique advantages such as high degree of equipment automation, complete automatic detection and control means and methods of various process technical parameters, continuous production, high production efficiency, low labor costs, and stable product quality. It is the preferred printing and dyeing processing method for cellulose fibers and blended and interwoven woven fabrics. However, if the quality, process, technology, and operation management are not in place, batch quality problems are often prone to occur, resulting in batch repairs, increasing quality costs, or worse, defective products that cannot be repaired and cannot be delivered, seriously affecting the company’s production schedule and economic benefits. and credibility.
For this reason, the causes and preventive measures of the main defects that often occur during the open-width continuous dyeing and finishing of woven fabrics are briefly described below.
Original color difference, front and back color difference
1. Causes:
1. The operation is not standardized when coloring the sample, and the process parameters are not well controlled. The coloring sample cannot reflect the true color of the dyeing formula.
2. When the cart is staked out, the weighing is inaccurate, the chemical materials are inaccurate, and various process and technical parameters are not properly controlled. The staked out samples cannot reflect the normal color of the dyeing formula, which affects the color matching. Deviations from personnel’s normal judgment and formula adjustment.
3. The customer’s samples were not carefully analyzed. The dye combination selected for the dyeing formula was different from the dyes used in the customer’s samples. There was metamerism (light jumping) phenomenon. Different colors appear under different light sources.
4. The colorist’s vision error leads to inaccurate color matching.
5. After the imitation color of the small sample and the setting out of the large truck, finishing was not carried out according to the customer contract standards, resulting in color and light changes when the large goods were finished.
6. The dye properties in the dyeing formula are too different, and the color of the fabric changes too much when the process parameters fluctuate during the cart production process.
7. The hair effect, whiteness, pH value, desizing and sanding effects of semi-finished products before dyeing are inconsistent.
8. The main process technical parameters fluctuate during dyeing, such as the fluctuation of the dye liquid level in the pad tank, the speed of the machine, the pre-baking temperature, the baking temperature, the pad pressure, the reduction (fixation) ) Fluctuations in temperature, time, dye concentration, fixative solution, reducing solution concentration, etc., lead to color changes.
9. The dye changes color during ironing, resulting in inaccurate color matching.
10. Reasons for gray fabrics: Gray fabrics from different manufacturers and different batches of the same manufacturer often have different textures after treatment due to different quality of cotton fibers, different twists of yarns, and different sizing of warp yarns. Differences in water absorption and dyeing properties lead to color differences between pieces during dyeing.
11. Reasons for dyes: There are differences in the shade and strength of dyes from different manufacturers and different batches of the same manufacturer.
2. Preventive measures:
1. Carefully analyze the customer’s incoming The fiber type, dye type used, color light source, finishing effect, etc. shall be determined using the same specifications of gray fabric, the same type of dye, and the same finishing process as required by the contract. If the customer’s sample is different from the contracted fabric, the sample should be imitated and submitted to the customer for approval before large vehicle production can be organized.
2. Sample coloring personnel and truck coloring personnel must be trained and tested for color discrimination ability, and the vision of relevant personnel should be unified.
3. When performing color matching operations, ensure the consistency of color matching conditions, such as color matching light source, brightness, observation angle, distance, etc.
4. Strengthen the performance testing of dyes used, such as the high-temperature baking and color-fixing properties of disperse dyes, the directness of reactive dyes, specific shift values, alkali resistance and temperature resistance, etc., to ensure their use Dye application performance is consistent.
5. Strengthen the management of weighing, chemical mixing and batching to eliminate errors and reduce errors.
6. Strictly operate the machine and ensure that the technical conditions of each process meet the process design standards.
7. During normal production, a large production standard sample should be left at the machine’s cloth drop area. The cloth dropper, captain, and color checker can check the sample at any time to detect problems in a timely manner. deal with.
8. When comparing colors, the sample must be fully cooled to achieve normal moisture regain. You can use steam moisture regain or hair dryer drying method.
9. Strengthen the management of gray fabrics, and try to use the same batch of gray fabrics from the same manufacturer for one contract and one color position.
10. The same manufacturer and batch of dyes must be used for sample imitation, cart staking, and normal production to prevent color fluctuations due to dye differences.
Left, center and right color difference
1. Causes:
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1. The left, middle and right hair effects, whiteness and mercerizing effects of the semi-finished products are inconsistent.
2. When polyester and blended and interwoven fabrics are being shaped, the left, middle and right temperatures in the box are inconsistent.
3. The sanding effect on the left, middle and right sides of the fabric is inconsistent.
4. When dyeing, the air pressure at both ends of the padding car and the oil pressure in the middle of the padding car are not uniformly controlled during dyeing and dyeing. The pressure on the padding car line is inconsistent, resulting in different amounts of liquid on the left, middle and right sides of the fabric. ; The concentration of the dye liquor (reducing liquor, fixing liquor) in the padding tank is inconsistent; the degree of drying of each part during hot air drying and drum drying is inconsistent, resulting in dye migration; the baking temperature during dispersed baking of polyester blended and interwoven fabrics The left, middle and right are different; the wear degree of each part of the uniform rolling car is different. The temperature of the reduction (color fixing) steamer is not enough.
5. The performance of the color matching dyes selected for dyeing formulas is very different.
6. Rolling during finishing and shapingp>4. When the air volume is too large during hot air drying, the fabric will not run smoothly and cause wrinkles.
5. The pre-setting temperature of polyester blended fabric is too low, the width is too narrow, needles are off, etc.
6. The mercerizing expansion is not enough and the door width is too narrow; the cloth clips of the cloth clip mercerizing machine are worn, deformed, stripped, and the chains on both sides wear inconsistently, etc.
7. The weft skew of the fabric is too large.
8. The bending roller is worn or the angle is wrong and the expansion effect is poor; the cloth guide roller is bent and deformed.
9. Before sanding, the folded and piled fabric surface of the sanded fabric is uneven, and wrinkle marks are formed during sanding; the polyester blended fabric is folded and stored at too high a temperature before dyeing. If the time is too long, wrinkle marks will form.
10. Compact fabrics are folded and stacked for steaming, which is prone to wrinkle marks during steaming.
2. Preventive measures:
1. Strengthen the safety of mechanical equipment Maintenance to maintain mechanical flatness, uniform rolling pressure, and improve the adaptability of equipment varieties.
2. When shrinkage strips appear on gray fabrics, gray fabrics can be used for shaping; before dyeing, make sure the temperature reaches above the dyeing temperature.
3. The fabric dropping process before sanding is rolled up to prevent wrinkle marks.
4. The compact fabric adopts cold pad batch pre-treatment process to eliminate wrinkle marks.
5. Strengthen the inspection of the tracks (chains) of the setting machine and mercerizing machine to ensure that the lengths of the chains on both sides are consistent and that the cloth clips and needle sheets are intact.
6. When the fabric is pre-dried with hot air, the air volume of the circulating fan should be reasonably adjusted according to the characteristics of the fabric. Thin fabrics should reduce the air volume.
7. Strictly control the weft skew of the fabric in each process, and there should be no wrinkles during weft straightening with a weft straightening device. For a machine without a weft straightening device, if there is a huge difference in the weft inclination between the cloth incoming and outgoing wefts, find the cause and deal with it promptly.
Editor’s Note
Today, with the rapid development of printing and dyeing technology, printing and dyeing Processing must adapt to the requirements of low-carbon and environmental protection, and rely on technological progress to apply textile printing and dyeing auxiliaries with excellent performance to achieve low-temperature and efficient short-process processing methods to improve production efficiency and reduce production costs. Strengthen enterprise quality management, do a good job in pre-production preparation of products, formulate preventive measures for possible quality and technical problems, and focus on prevention. Strengthen process quality control to ensure the first-time success rate of products, eliminate large-volume repairs and defective products, and improve product quality reputation and corporate visibility.
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