01 Formation and processing of singeing folds
When dyeing, sometimes you will see double or multiple black folds on the cloth surface after pad dyeing, and there are fluffy white wool strips next to the black folds. This kind of folds is singed folds. The white marks that appear after the folds are baked will turn into deep black folds after the color is restored. The singeing folds are caused by the uneven cloth surface catching the folds when passing through the burner during singeing. Due to the high temperature of the burner, the area where the folds are formed will be burned. Since the creases cannot be burned, there are white strips of wool next to the black folds. .
Prevention: First of all, no folds should be made during singeing, and reasonable production processes should be formulated according to different fabrics. Thick fabrics should be piled or boiled before being singed, so that the singeing can be flattened into the fabric to reduce the possibility of folds in the singeing machine. Furthermore, That is, wet drop cloth is used for singeing to prevent the high temperature of the drop cloth from aggravating the degree of folding.
If there are singeing folds found during dyeing, it must be pre-treated and repaired before dyeing. Once the production is started and dyed, the black folds will not be processed. The method of pre-processing and repairing the singeing folds is very simple. You only need to set the cloth at high temperature to flatten it, then singe it, and then use low-alkali mercerization to eliminate the singeing folds.
02 The formation and processing of boiled rice dumplings
Roughened folds are more common in high-count and high-density polyester-cotton fabrics and pure cotton thin fabrics. During production, scale is formed during steaming and cleaning due to high water hardness, which is easy to adhere to the cloth guide roller. During long-term production, scale grooves will be formed, making the cloth guide roller inoperable. If it is flat, the fabric will fold easily. Once folds are found during production, the car should be wiped and cleaned in time. If semi-finished products are found to have folds during dyeing, reasonable techniques should be used to repair them.
Introducing several methods for repairing broken parts:
1. If the bleached fabric has uneven temporary creases or mercerized creases, it can be dyed directly without considering the impact on dyeing. If it is more serious, it can be dyed and produced as long as it is pre-shaped.
2. If there are obvious folds in the bleached fabric, and there is no fabric damage, the dyeing machine will show black folds. If the folds cause fabric damage, then the bleaching machine will show a white fold mark. For this kind of fold, you can use high temperature over-width stretching and then mercerization for repair.
3. The cloth after bleaching is seriously creased, and the creases on the cloth surface have formed aurora marks. This kind of creases is difficult to deal with. The only way is to stretch the fabric at high temperature and then perform a light sanding process to polish the creases. It is printed and polished, then boiled and bleached again to expand and repair the damaged fabric fibers, and finally the creases are smoothed out by high-concentration alkali mercerization treatment.
It is emphasized here that when repairing a fold, it is very important to accurately determine the cause of the fold first. Different treatment and prevention methods for different folds are different to avoid waste caused by unnecessary processes. For example, mercerized drying fabrics are easier to detect. Once discovered, they should be dealt with immediately. Do not leave the problem until dyeing before finalizing. If the dried folds are difficult to handle, you can spin the folds during mercerizing. This will flatten the dried folds and use the residual heat of the dropped cloth to iron the folds flat. This will save you the time of setting before dyeing. (There are several disadvantages to setting the fabric before dyeing: high temperature of the fabric will easily cause folds. If the setting effect is not good, it will easily cause needle breakage. For sensitive colors, it is easy to have defects such as the setting edge folding and white edges. Setting the fine woven fabric before dyeing will aggravate the rain. Striped fabric noodle shadow. Therefore, it is best not to set the finished semi-finished product before dyeing. If necessary, the setting temperature should be controlled at 170-180℃.)
03 Formation and treatment of track marks
Track prints often appear in heavy fabrics. When dyeing, they are both track prints, but due to different forms, the shapes displayed on the fabric after dyeing are also different (black marks, white stripes).
Commonly seen tracks are marked with messy black rungs in the weft direction. This track mark is caused by stacking indentations caused by too thick a pile of fabric in the track box. Sometimes, if the track mark is light, it can be ignored. It won’t be too obvious after dyeing. If the folds are too obvious, just heat them and wash them again to remove them. But there is another kind of white stripe track mark that you may rarely encounter, and it is not clear why it is caused by the track. Everyone knows that saturated steam is used to boil and bleach the track box for production safety. The superheated steam heats the water in the track box water tank to generate saturated steam to treat the fabric. However, if the water level in the track box is low and there is too little water, the track box will be full (240 ℃ high temperature superheated steam, so the temperature of the track plate (roller) will be too high, which will burn the fabric contact surface and form dye-repellent white spots. The longer the storage time, the heavier the white spots will be. Once the equipment fails at this time, the white spots will It’s difficult to repair, so I think the white stripes are also caused by the tracks, so we classify them as track marks.
Once this kind of white stripe track mark is formed, it is very difficult to remove because it causes damage to the fabric, so it must be strictly guarded during production. When driving, the operator should pay attention to the stacking shape, thickness, and water level in the track box (neither the water level is too high) Not enough to flood the steamer).
What should be done if such white stripes are found during dyeing?
The hot alkali pile process is used, and then concentrated alkali mercerization is used to increase the penetration and dye absorption rate of the burnt area. Even after such repairs, the heavier track marks are still white.
The following can only be compensated by improving the dyeing process:
(1) For lighter track marks, two dips and two pads can be used or a pressure roller in the trough can be used to extend the immersion time to reduce track marks.
</�At the same time that the production is safe and reliable, the cotton impurities should be treated as cleanly as possible, and the dead cotton should be boiled thoroughly to improve the dye uptake rate and the quality of the dyed cloth products.
Due to the energy saving, many companies are now using cold pile pre-processed fabrics. However, the effect of cold pile on removing cotton impurities and slurry is poor. The fabric is relatively stiff, so it is easy to wrinkle during dyeing, and the cloth guide roller is easy to get dirty and cause stains. spots, so less viscous additives should be added during dyeing production, such as: anti-migration agent, whitening agent NT-2, etc.
When producing polyester-cotton brushed fabrics or pure cotton thick fabrics, if the rinsing effect is poor and the cotton wool is not cleaned properly, some fine cotton wool will stick to the cloth surface, which will be more difficult to remove after rolling and rolling, and white spots will form during dyeing. . Some dyed white spots are not obvious after using the machine, but if you rub the cloth surface with your hands in reverse, the cotton wool will fall off and many white spots will be exposed. There are also tiny cotton wool stuck on the cloth surface that are very difficult to remove and difficult to find even in the continuous dyeing machine. However, when it is necessary to add anti-wrinkle, rainproof agent, cross-linking agent and other viscous additives during tentering, the cotton wool will stick down and white spots will be exposed. . Therefore, white spots caused by cotton wool should not be underestimated. When producing sanded products, attention should be paid to diligently cleaning the cotton wool in the sanding machine blower, exhaust fan, and brush roller to prevent it from adhering to the cloth surface and making it difficult to wash after being rolled by the cloth rolling machine. Come down. If the cotton wool is still not clean after cleaning on both sides, you can brush it again with a bristle roller on the sanding machine, and then the dyed cotton wool will be clean.
For fabrics with a lot of cotton and dead cotton, increasing the alkali concentration (220g/L) during mercerization can effectively improve the surface quality of colored fabrics and reduce white stars and fabric stains.
During the production process of sanded fabrics, you must pay attention to the aurora prints, because once there are aurora prints, white spots will form during dyeing. Therefore, during mercerization alkali washing after sanding, there should be no hard objects stuck to the pads and cloth guide rollers. During frequent inspections, white spots with aurora prints are found during dyeing, which should be dealt with first.
09 Formation and prevention of pollution during dyeing
In the production of colored fabrics, orange, bright pink and other particularly bright colors are often produced, and fluorescent materials are used for production. However, during production, you may find a layer of black air on the fabric surface, which makes the fabric surface look particularly flowery. This is pollution.
Smell is usually caused by the following conditions:
1. The singeing is not clean.
If the singeing effect is poor, a layer of short fluff will remain on the cloth surface. During dyeing and production, the infrared ray of the primer is too close to the cloth surface and the speed is slow. The infrared ray will burn the short fluff on the cloth surface and form sewage. The production of darker colors will not be obvious, while the beautiful colors will be obvious.
2. Improper material selection results in seemingly black odor.
If fluorescent materials are used as dispersing materials and darker dyes are used as active materials in production, it will also cause a layer of black odor on the cloth surface due to inconsistent color and light. Moreover, the polyester-cotton fabric itself has a higher finish and brightness than cotton. Dying particularly bright colors of polyester and cotton can easily cause inconsistencies in hue and brightness. Therefore, when producing bright colors, cotton processing should be strengthened to ensure the whiteness of the fabric, so that the hues of colored fabrics, polyester and cotton are basically consistent. Prevent the generation of pollutants.
3. Caused by improper dyeing process.
For example: use dispersed fluorescent red, dispersed fluorescent peach, and dispersed purple to produce bright pink. If the baking temperature is low, the dyed cloth surface will be dark and flowery. If the baking temperature is high, the dyed cloth surface will be bright and plump. At this time, because the dispersed fluorescent pink can fully develop the color and reflect the beautiful fluorescent effect at high temperature, it should be based on the required Only by selecting dyes and formulating a reasonable production process can we produce bright and plump colored cloths.
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