Printing is a kind of local dyeing. Therefore, when choosing to use the same type of dye for printing or dyeing, the physical and chemical properties of the chemical additives used are similar, and the principles of dyeing and fixation used are also similar. The dyes on the fibers must also have various dye fastnesses that the fabric should have during use such as wearing. These are the common points between printing and dyeing.
1. The difference between dyeing and printing
1. Dyeing solutions generally do not add thickening paste or only add a small amount of paste, while printing pastes generally add more thickening paste. This prevents the pattern from blurring out, resulting in unclear or distorted pattern outlines, and prevents dye migration during drying after printing.
2. The dye concentration is generally not high during dyeing, and the dissolution of the dye is not a big problem, so co-solvents are often not added. The dye concentration of printing paste is high, and because more paste must be added to the paste, it will be difficult to dissolve the dye, so more cosolvents are often added. For example, urea, alcohol, dissolved salt B, etc.
3. When dyeing (especially dip dyeing), the fabric has a long action time in the dye bath, which allows the dye to Diffuse and penetrate into the fibers fully to complete the dyeing process. When printing, after the paste added to the color paste is dried to form a film, the polymer film layer affects the diffusion of the dye into the fiber. Post-processing methods such as steaming and baking must be used to increase the diffusion rate of the dye to help the dye. Dyed fibers.
4. Two different types of dyes are rarely used to match colors during dyeing (except when dyeing blended fabrics), while printing often Use different types of dyes for co-printing, or even printing with the same paste. In addition, there are various processes such as discharge printing, resist printing and resist printing, so the printing process design is different from dyeing.
5. Printed fabrics have white ground printing, or white-out or anti-white printing products, so pre-processing of semi-finished printed fabrics is required. , which has similar whiteness requirements to bleached cloth semi-finished products, while dyed cloth semi-finished products have lower whiteness requirements.
6. The semi-finished products of dyed cloth are required to have a good capillary effect to facilitate the dyeing process.
Diffusion and penetration into the fiber. When processing printed fabrics, printing and drying are continuous and often completed within a few seconds at the same time. The printing pattern is required to be uniform in color, clear in outline, and
The lines are smooth and unbroken. Therefore, the scouring and bleaching semi-finished products of printed fabrics not only require a good capillary effect, but also a uniform and good instantaneous capillary effect, so that the fabric can use the capillary effect to remove the printed pattern at the moment of printing. Color paste is “acceptable”.
2. The difference between dyeing and printing
1. The differences between dyeing and printing are as follows
① Printing is better than dyeing at covering defects in gray fabrics.
② Printed fabrics have particularly strict requirements on the weft and skew of semi-finished products.
③ Dyeing and printing may have special requirements for the same type of dyes
④ Dyeing and printing have different pre-processing requirements for semi-finished products. (Such as whiteness, wool effect)
⑤ No or a small amount of thickening paste is added to the dyeing solution, and the printing paste is added More thickening paste.
⑥ During dyeing, the dye penetrates and diffuses fully. When printing, the dye is not easy to diffuse and penetrate, and must be steamed or baked.
⑦ Dyeing solution, the dye is easily soluble, no co-solvent is added. For printing paste, add more co-solvent.
⑧ Dyeing rarely uses two different types of dyes to match colors. Printing often uses different types of dyes
2. There are three similarities between dyeing and printing:
① The same type of fiber can have the same color fastness if dyed and printed with the same dye.
② The physical and chemical properties of the chemical additives used are similar.
③ The principles of dyeing and fixation using dyes are similar.
