Several methods for controlling color difference between large goods and small samples

01 Cleaning method

A:Cold water cleaning

In cotton and its blended interwoven fabrics, if the cotton component is dyed with direct dyes or reactive dyes, and the color appears floating or dull, it is generally necessary to continue washing with water, or add additives to the water bath for washing. If the water hardness is high, 0.5~2g/L chelating dispersant can be added to improve it.

B:Warm water cleaning

When dyeing polyester blended interwoven fabrics, there are many types of dyes and auxiliaries used. Washing at 40°C can be used to facilitate the dissolution of residues contaminated on the fabric. Cellulose fibers are dyed with direct blended dyes. If the overall color of the large sample is darker than that of the small sample, the color will be similar after washing with warm water, and the color fastness can be improved to a certain extent.

C: Hot water cleaning

Hot water cleaning is mostly used for silk or synthetic fibers and their interwoven fabrics dyed with acid, direct and basic dyes. If the color is darker, 1 to 20% of the dye needs to be removed, and you can use hot water washing at 70 to 80°C. 0.3~0.5L of Pingpingjia 0 (leveling agent) can be added to the hot water bath of silk fabrics. For polyester, nylon and other synthetic fiber blended fabrics, 0.5 to 1.0L of repair agent or dyeing carrier can be added. Since the amount of additives added in the hot bath is small, the fabric only needs to be washed with running water to room temperature. If dyed fabrics are treated with cationic fixatives and softeners, it is best to add 2 to 4L of dispersant DAM to the hot bath. In principle, hot water washing (repair) should be carried out on the original dyeing equipment. For example, after jig dyeing of nylon, acetate fiber and interwoven silk, if the overflow machine (rope type) is used for hot water washing, the fabric will cause permanent wrinkles.

02 Auxiliary method

  1. Add electrolyte
  • When direct dyes are used to dye cellulose fibers, the dyeing depth is often not enough for large samples. If there is still dye in the dye bath, 1.5-5.0g/L electrolyte (NaCl, Na2SO4) can be added to promote dyeing. This is suitable for salt effect direct dyes, such as direct lightfast yellow 3RLL, orange (L, bright red BNL, red 4BL, ruby RNLL, purple BL, blue BL, B2RL, sky blue G, emerald blue GL, green 5GLL, green GL, gray 4GL, gray GB, etc. are very effective. For temperature effect direct dyes, a certain temperature needs to be maintained.
  • Use acid dyes to dye protein fibers, or use basic dyes or cationic dyes to dye acrylic fibers. If the color of the dyeing sample is too dark or has flowers, add 3 to 6 g/L Na2SO4 to fade or level dye it.
  1. Add acetic acid

(1) Use acid dyes to dye silk, wool and other protein fibers. If the dyeing sample is lighter and there is residual color in the dye solution, 0.5-2mL/L 98% acetic acid can be added to promote dyeing. The steam valve must be closed before adding, dilute it with 10 times cold water, and add it slowly while the dye is running to avoid causing new color flowers.

(2) Use K-type and KN-type reactive dyes to dye cellulose fibers. If the sample is too dark, you can add 2-3mL/L 98% acetic acid and treat it at 90-95℃ for 3Omin to promote the dye to break the bonds and eliminate the color. Generally, it can be reduced by about 20%.

(3) When dyeing silk with alkaline dyes or dyeing acrylics with cationic dyes, if the sample is too dark, you can use 2~3mI/L acetic acid and treat it in a warm water bath at 40~60℃ for 20~30 minutes to dissolve the dye. Reduce the color by 20% to 30%.

  1. Add leveling agent

(1) Use disperse dyes to dye polyester and its blended interwoven fabrics. When the large sample is darker than the small sample, a high-temperature leveling agent or repair agent can generally be added. If the color of the large sample is light, you should add the corresponding dye, but you should be careful to close the steam valve when adding to avoid color blooming. Add an appropriate amount of leveling agent first. In addition, when dyeing with disperse dyes, the temperature must be raised to a certain dyeing temperature and kept for 15-20 minutes, and then the temperature and pressure should be lowered and the sample should be checked.

 

(2) When dyeing cellulose fiber, silk, wool and nylon fabrics with direct, acidic, neutral and other dyes, in principle, flat addition of O can be used to remove the migrating dye to achieve level dyeing. The amount of O added to wool fabrics generally cannot exceed 0.3g/L. In order to prevent wool from felting, wool protective agent WOK 2% to 3% (Dystar) can also be added. When dyeing nylon with neutral dyes, if the color of the large sample is too dark or there are rungs that need to be covered, using N-ER 3% to 5% (D’ystar) will have excellent results.

 

  • When dyeing acrylic, alkali-modified polyester and silk with alkaline and cationic dyes, if the color of the dyed sample is slightly darker, hot water can be used to clean it; if the color of the sample is about 20% darker, the dyeing residual liquid can be basically washed When washing is complete, add 2 to 4L of surfactant 1227 to achieve fading through competitive dyeing.
  1. Add whitening agent

When dyeing bright colors such as ruby, rose red, violet blue, azure, sky blue and brilliant purple, if you feel that the large sample is not bright enough, you can generally add 0.0015% to 0.0025% (owf) fluorescent whitening agent. The lighter the color, the dosage The less. For cotton textiles, the fluorescent whitening agent 4BK has a better effect. It has weak fluorescence, strong brightness, low dosage, good adjustability, and wide adaptability to colors. “Light popping” caused by fluorescent whitening agents can be removed with a fluorescent stain remover that does not affect the brightness of the color.

 

E.Add staining carrier

For polyester-cotton and nylon-cotton, since polyester and nylon are hydrophobic fibers, their color is deeper than that of hydrophilic fibers such as cotton and viscose. You can add 2-4mL/L dyeing carrier in a 60°C clean water bath, and then gradually increase the temperature. to 80~9O℃, the dye on the hydrophobic fiber is slowly desorbed, and the two-phase color light is consistent. Practice has proven that the dyeing carrier can not only dissolve disperse dyes on hydrophobic fibers, but also has the ability to dissolve other dyes. When the temperature rises to 80°C, the operator must continuously take samples to check, and generally keep the temperature until the large and small samples match.

03 Add Dye (pigment) method

  1. When adding disperse dye to polyester for color correction, it is best to lower the dye bath temperature to below 80°C, then fully dilute the previously dissolved dye, and finish adding it within 5 to 8 minutes, and then continue to increase the temperature to the original dyeing temperature. Insulation dyeing for more than 15rnin ensures that the front and back colors are evenly dyed to reduce the impact on heat setting.
  2. If the color difference between the large and small samples is found after the dye comes out of the vat, you can add additional dye or adjust the color light on the large sample. When adjusting, in addition to calculating the type and quantity of dyes required on the large sample, 15% to 20% of the original prescription dyes should also be added to the blank bath.

C. For colors made up of 3 to 4 dyes, such as rice gray, tile gray, fragrant gray, silver gray and ivory white, etc., dyes (pigments) cannot be used to repair the color difference between large and small samples

 

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