What are the nylon dyeing experiences?

 

1. The nylon fabric needs to be washed before setting

Normally dyeing nylon and spandex fabrics requires washing before setting, because the content of spandex is high, and the relative amount of silicon lubricant is relatively high (the content of silicone oil in spandex is generally up to 8%). If the silicone oil is not removed before the setting, Then, when the embryo is at high temperature, the silicone oil will be cross-linked and will be adsorbed on the nylon yarn, which will seriously hinder the dyeing of the acidic materials during dyeing, thereby forming dyed flowers.

a. Generally, dry-cleaning machine (perchloroethylene as extractant) is used for airtight degreasing. This is a better method, and the removal efficiency of silicone oil is high;

b. Second, a flat-width washing machine will be used, which can adjust the number of feeding tanks and washing tanks, add degreasing agents and chelating dispersants, and overflow and drain each tank, and the total water consumption is controlled at 1:40-1 ：60. Generally, the degreasing efficiency is only 30%-40%, but it can make the oil distribution of the cloth more uniform and improve the dyeing. It is important to pay attention to the selection of degreasing agent and dispersant to prevent the silicone oil from demulsification and staining. Leukoplakia is formed when;

c. Third, the beam cylinder or JET cylinder will be used to remove oil first (including some indefinite embryos, which are directly dropped for oil removal and dyeing). The oil removal efficiency will be relatively high, but it is necessary to pay attention to the cloth surface problem. If there is no pre-shrinking, directly drop the dye tank to remove the oil. After dyeing, creases and chicken feet marks will easily appear on the cloth surface. It is recommended to wash it with open width (phase dye pre-shrink to relieve stress), and then drop the tank to remove the oil;

2. High temperature predetermined embryo affects dyeing

Nylon fabric, under high temperature conditions, the terminal amino group is very easy to be oxidized (acidic material coloring group), if the nylon high temperature anti-yellowing protective agent 190 degrees and 193 degrees are not added, it will greatly absorb the color of subsequent dyeing As a result, nylon high-temperature anti-yellowing agent (expensive) must be added when setting the embryo, and it is usually recommended to use LANXESS (Bayer) GR 25-40g/l.

A straightforward mention is the problem of yarn splitting after purchase. We found that often after a batch of yarn comes back, one or two yarns are always colored differently from other yarns. Sometimes the storage conditions of the yarn count will also cause the difference in the color absorption of the nylon yarn, so the storage of the nylon yarn is very important.

3. The choice of dyes when dyeing

Light-colored printing and dyeing auxiliaries try to use small molecule dyes with high leveling properties but poor fastness. Metal mordant dyes should not be used. Otherwise, a little difference in color absorption of the raw materials will be magnified, causing serious horizontal and vertical stripes;
In the acid color card of other major companies, each dye is divided into different level dyeing grades. The level dyeing grade is basically inversely proportional to its wet fastness, and the recommended dyeing temperature and pH. You can ask them for the color. Card reference, not much to say here

4. Determination of dyeing process

a. Corresponding to the results of the selection of materials, formulate different dyeing processes. Explain that the commonly used nylon 66 is dyed at 100-105 degrees, and 6 is dyed at 90-95 degrees.

b. pH is a key influencing factor. Carefully use smoothing agents, ammonium sulfate, acetic acid, and new slow-release acid agents. Generally speaking, ammonium sulfate is sufficient for light colors (if you choose Claraint, take a look at their introduction of dyeing pH ), for medium and dark colors, it is recommended to add some ammonium sulfate first. When the temperature rises to 80-90 degrees, the HAC is drawn into the curve without pressure. Of course, if you use a slow-release acid, you can add it at low temperature, and when the temperature rises , The acid is gradually released, the same effect is the same; everyone can do step-by-step dyeing in the chemical room, and analyze the influencing factors during dyeing to get the control method;

c. When printing and dyeing auxiliaries are lightly dyed due to fastness issues and have to use dyes with large molecules and low level dyeing, consider using retarders. First use CN to dye once, make CN sit first, then dye, when dyeing A weak cationic leveling agent can be used. For a darker color, pay attention to the drainage effect after dyeing and reduce the fastness;

d. When dyeing, bleaching or extremely bright colors, it is recommended to boil the white powder before dyeing.

5. Fastness control

After dyeing, please wash to the bottom of the water to clear, fix the color with an anionic fixing agent, and press the dye between the fixing agent molecules and the cloth body. If it is very dark and the fastness cannot be achieved, please fix it in an anionic fixing agent. After coloring, add cationic color fixation. This process can be selected in the dyeing vat or the sizing machine tank. Of course, pay attention to the problem of color stains and head-to-tail differences.

Nowadays, many companies have developed reactive dyes for dyeing nylon. The effect is good, but the price is too expensive.

6. The yellowing fastness of nylon plastic bags

This problem has been haunting dyeing and finishing producers. Light nylon is prone to yellowing of plastic bags. This type of customer complaints are the most, and compensation is often due to the problem. The cost of anti-yellowing treatment of plastic bags is relatively high and easy It can cause color change and increase the difficulty of dyeing and finishing. Dyeing vat treatment or post finishing treatment can be used.

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