What are the influencing factors of nylon and elastic fabric dyeingⅡ

2. The influence of dyeing temperature on nylon dyeing

Temperature is an important factor in controlling the dyeing of dyes. The temperature will affect the swelling degree of the fiber, the performance of the dye and the effect of the auxiliary agent. Nylon is a thermoplastic fiber, and the dyeing is very slow at low temperature.

The glass transition temperature of nylon 6 is 30~50℃, while the glass transition temperature of nylon 66 is 47~50℃. Generally, the initial dyeing temperature of nylon 66 can be controlled at about 40℃, while the initial dyeing temperature of nylon 6 is lower. . When the temperature of the dye bath reaches 70°C, the fiber expands sharply, and the dye uptake rate increases linearly. In the subsequent heating process, the heating rate should be strictly controlled. Of course, the effect of temperature on the dyeing rate is also different depending on the dyes. The dyes with smaller molecular weight and better levelness gradually increase with the increase of temperature, while those with larger molecular weight, levelness and migration Poor dyestuffs, only when the temperature of the dye bath is higher than 60%, begin to gradually increase with the increase of temperature, especially in the range of 65-85 °C, the heating rate should be strictly controlled. Dyed too quickly and caused colored flowers.

Therefore, the heating rate has a great influence on the dyeing, and the heating rate depends on the choice of dye, the shade of dyed color and the structure of the fabric. Step heating can be used to ensure the levelness of dyeing. The main function of the heat preservation stage is to obtain a certain migration of the dye, so the appropriate extension of the heat preservation time is helpful for the leveling and cover dyeing of the dye.

3. The influence of dye selection on nylon dyeing

The selection of dyes mainly depends on factors such as the type, hue, color depth and color fastness requirements of the dyed object. The selected dyes must have reasonable compatibility.

As far as the acid dye itself is concerned, its application performance is determined by the molecular structure itself. The simpler the molecular structure and the smaller the relative molecular mass, the greater the proportion of water-soluble groups contained, and the better the levelness, but the poorer the wet fastness. In order to improve the wet fastness of acid dyes, the proportion of organic groups will be increased to increase the relative molecular weight of the dyes and reduce the proportion of water-soluble groups, but the levelness and migration of the dyes will decrease. Therefore, it is necessary to start from the dyeing process and control the dyeing process to ensure the dyeing quality and prevent the occurrence of problems such as "colored flowers" and "willows".

The dyeing saturation value of nylon is very low, so the phenomenon of "competitive dyeing" among different dyes is very prominent when dyeing dark colors. If the selected dyes have a large difference in affinity and dyeing rate, the color of the fibers will be very different in different dyeing times, which is very easy to cause color patterns and poor color reproducibility.

In general, try to use the same series of dyes from the same company. Even if you have to choose dyes from different companies, you should try to choose dyes with similar dyeing curves, similar initial dyeing temperatures, and similar sensitivity to temperature and leveling agent. In order to minimize the "race dyeing" phenomenon between dyes.