What are the main points of cotton reactive light dyeing process

Because reactive dyes have the advantages of excellent performance, complete chromatogram and bright color and light, they have been widely used in medium and dark colors for many years. Now some light colors and light colors include difficult-to-dye light colors such as light rice and light gray. , light stone color, etc. are also increasingly replacing the traditional vat and soluble vat dyes in the past. However, in these light-colored dyeings for a long time, many dyers are accustomed to thinking that the time of dyeing is based on color. Depending on the depth, the time for dyeing dark and strong colors should be long, the amount of auxiliaries should be large and it should be added in batches. When dyeing light colors, the dyeing time can be short, and the amount of auxiliaries can be less, and it can be added in batches or at one time. As a result, the phenomenon of colored flowers, chromatic aberration or inaccurate color light in dyeing occurs from time to time. In fact, the reason for this phenomenon is precisely controlled by this traditional concept, that is, the process points that should be paid attention to have been ignored. This work is briefly analyzed and discussed for reference by peers.

1. Determination of dyeing time: The dyeing time depends on the depth of the color. The dyeing time for light colors should be short. In fact, this is a misunderstanding. The dyeing time should not be determined according to the depth of the dyed color or the amount of dye. According to the properties of the dye itself, such as directness, dye uptake or absorption rate, including some dyeing characteristic values such as fixation rate, fixation rate, etc., the dye will not increase the dyeing rate or speed up the fixation due to the light color. It runs according to its own performance, speed and curve. If dyeing is completed in the sensitive time period of dyeing or color fixing, it will easily cause uneven dyeing and color difference. On the contrary, if the dyeing or color fixing rate reaches equilibrium or saturation, then keep warm After a period of stability, level dyeing, penetration dyeing and stable shade can be obtained, thereby avoiding the generation of chromatic aberration. Therefore, the time of dark and light dyeing should be basically the same. According to experience, it can be generally controlled after adding salt and heating for 20-30 minutes and then adding alkali to fix the color and then keeping it warm for at least 30-40 minutes.

2. Feeding method of additives: Due to the small amount of light-colored additives, it is considered that it is not necessary to add them in batches and batches like dark-colored additives during feeding, but can be pumped in at one time or quickly. In fact, this is even a misunderstanding. The time or frequency of adding dyeing auxiliaries should not be determined according to the number of auxiliaries, but according to the effect of dyes and auxiliaries and the rate and performance of mutual chemical reaction. Under the action of auxiliaries and temperature, the dyeing rate and the reaction rate with cellulose anions become faster, resulting in the adsorption and fixation on the fiber in a short time, resulting in uneven dyeing or color pattern. If the auxiliaries are still added in batches or multiple times, the dyeing of the dye and the reaction with the fiber will be milder, and there will be no rapid or instantaneous dyeing phenomenon, thus effectively avoiding color flowers, such as some special For the light color that is difficult to dye, the salt and alkali can be added in batches in 2-3 batches. That is, 1/6, 2/6, 3/6 or 1/10, 3/10, 6/10, etc., and the interval time should also be controlled at least 10-15 minutes.

3. Other process requirements and points of attention: In the production of some difficult-to-dye light colors, in addition to improving the above items, temperature, bath ratio and time are the three major elements of dyeing that need to be strictly controlled. The recommended bath ratio should be It should be as large as possible, the speed should be higher than that of conventional dyeing, and the amount of cylinders should not be too large. In addition, the post-processing at the end of dyeing is also a factor that cannot be ignored that affects the color light and fastness. Of course, these are based on the correct dye selection and On the basis of good semi-finished product quality.