The similarities between printing and dyeing

During the printing and dyeing processes, the mechanism by which dyes infect fibers is the same, both involving three stages: adsorption, diffusion, and fixation, which are both distinct and interrelated yet mutually restrictive. In the printing process, a certain color of dye is applied to a certain part of the textile according to the requirements of the pattern. After certain post-treatment, the dye is applied to the fibers, and then a printed product with one or more colors is obtained on the textile. So, printing can also be described as "partial dyeing".

When the same type of dye is used for dyeing and printing, the physical and chemical properties of the chemical auxiliaries used are similar or the same, and thus their dye adhesion and fixation principles are also similar or the same. For the same type of fiber products, if the same dye is used for dyeing and printing, they can have the same color fastness in all aspects. For example, when dyeing with VAT dyes, the fastness is good, and the fastness on printed products is also good.

The differences between printing and dyeing lie in the following aspects

In the printing and dyeing operations, dye water solution is used for dyeing processing, and generally no thickening paste is added or only a small amount of paste is added. The printing process uses color paste, which is a viscous paste made by adding a large amount of thickening paste to the dye solution or dispersion. This is to prevent unclear pattern Outlines, distorted patterns, and dye migration during post-printing drying due to pattern seepage during printing.

2. During dyeing, the dye concentration is generally not high, and the problem of dye dissolution is not significant. Usually, no co-solvent is added. During printing, the concentration of dyes and chemical auxiliaries in the color paste is much higher than that in a general dye bath. Moreover, it contains a large amount of paste, which makes it difficult for dyes to dissolve. Therefore, co-solvents such as urea, alcohol, and dissolving salt B need to be added to the printing paste.

3. During dyeing (especially immersion dyeing), the fabric has a longer action time in the dye bath, allowing the dye to diffuse and penetrate into the fibers more fully to complete the dyeing process. When printing, the dye is in the paste and is not easy to diffuse and penetrate. Therefore, after printing, post-treatment methods such as steaming or baking are required to increase the diffusion rate of the dye and help it dye the fibers.

4. When dyeing, if color matching is required, it is generally necessary to use dyes of the same type for color matching. It is rare to use two different types of dyes for color matching (except when dyeing blended fabrics). Printing, on the other hand, can be carried out by using several different types of dyes on the same textile, such as printing coatings and insoluble azo dyes together, reactive dyes and insoluble azo dyes together, reactive dyes and fast sulfonates together, insoluble azo dyes and polycondensation dyes together, etc. Sometimes, different types of dyes can also be used in the same color paste for in-paste printing. For example: coatings and insoluble azo dyes in the same paste, disperse dyes and reactive dyes in the same paste, etc. In addition, there are various processes such as discharge printing, anti-dyeing printing and anti-dyeing printing, so the design of printing processes is different from that of dyeing. Printing workers must have a profound understanding of the characteristics of various dyes and auxiliaries, and utilize the contradictions and compatibility among them to serve the products, printing out some printed products with special styles.

5. The dyes used for printing and dyeing are largely the same, but there are also some specifically designed for printing, such as reactive dyes for printing (domestic P-type reactive dyes, etc.), stable insoluble azo dyes, and soluble VAT dyes, etc.

6. Printed fabrics include products with white ground printing, or those with pull white and anti-white printing. Therefore, the whiteness requirements for semi-finished printed fabrics are similar to those for semi-finished bleached fabrics. Generally, they still need to be bleached after printing. However, the whiteness requirements for semi-finished dyed fabrics are relatively low, especially when dyeing deep and intense colors, the pretreatment does not need to be bleached.

7. The control requirements for the weft skew of the fabric during dyeing are not high. When printing, there should be no weft skew, especially for patterns such as checkered, horizontal bar, square or figure patterns. The weft skew requirements for semi-finished products are very strict, and there should also be certain requirements for the width of the fabric to avoid pattern skew and deformation of the pattern on the fabric when the width is stretched after printing.

8. Semi-finished dyed products are required to have a good capillary effect to facilitate the diffusion and penetration of dyes into the interior of fibers during dyeing. During the printing process, the printing and drying are continuous, with a short dye action time. It is also required that the printed patterns have uniform color, clear contours, smooth lines, and no broken lines. Therefore, for printed semi-finished products, not only should the rough effect be uniform and have a good "instantaneous rough effect", but also each step of the pretreatment process is very important. Only by obtaining good semi-finished product quality can the printing quality be guaranteed. Therefore, the pretreatment requirements for printed semi-finished products are higher than those for dyed semi-finished products.

9. Printing has a better concealing effect on defects in the fabric than dyeing, especially for some disordered patterns, it has a good concealing effect on certain fabric weaving defects.

For colored textiles, dyed products require uniform and rich colors, bright and transparent to the core, while printed products demand clear and elegant patterns, well-defined floral Outlines, fresh and white flowers, rich colors, and artistic qualities.