Printing is actually a local dyeing, so the dye fixing principle of printing is similar to dyeing. But printing pays attention to the effect of patterns. In large-scale production, the printing process has the following characteristics:
1. Printing uses the original paste as the medium. In order to stabilize the pattern and prevent the pattern from seeping in the printing process, nearly half of the original paste should be added to the printing paste; and the dyeing medium is usually water.
2.Co-solvents are often added to printing pastes. Due to the thick requirements of printing pastes and the small amount of water, it is difficult to dissolve the dyes. It is often necessary to add co-solvents such as urea and dissolved salt B.
3. The fixing time is short and the temperature is high. The process of making printing dyes dye fibers under high temperature is called evaporation. The dyeing of printing dyes needs to go through several processes of "seal film hygroscopic expansion-dye redissolution-dye transfer-dye dyeing", and the entire steaming process should not take too long, otherwise the sharpness of the pattern outline will be affected. Therefore, high-temperature methods such as steam and baking are often used in production to speed up the diffusion of dyes, help dyes dye fibers, and shorten the steaming time. Under normal circumstances, the dyeing time should not exceed 40min, and the temperature should not be lower than 100 ℃.
4. Vat dyes need to be screened. Printing is local dyeing. When the same type of dye is used on the same fiber fabric, printing and dyeing have the same principle and reflect the same color fastness. However, not all dyes can be used for printing. Commonly, Cotton Printed Fabric For Bedding. In view of the printing pattern, the stability requirements of the color paste, and the particularity of the steaming and washing environment. Printing has different requirements for dyeing than dyeing. Generally speaking, printing dyes should have good solubility, stability, color fastness, and small directness to the fibers. In the case of anti-discharge printing, the dyes must also have pull-out resistance or pull-out resistance; Dyes used for co-printing or same-printing should have good compatibility.
Cotton Printed Fabric For Bedding
5. Semi-finished products require high pre-treatment. This is mainly reflected in three indicators: whiteness, instantaneous hair effect and weft skew. For the direct printing process, in order to clean the white ground and highlight the vividness of the flowers, semi-finished products are often required to have good whiteness, especially in the anti-discharge printing process; secondly, the time of the printing process is short and the color of the printed pattern is required to be uniform , The outline is clear, the lines are clean, and the stem cannot be broken, so the semi-finished product should have a better capillary effect, especially it should have a good instantaneous capillary effect, and the hair effect is uniform, so that the fabric can quickly absorb the color paste and reduce the paste. Defects occur; the printing effect is irreparable due to the existence of the pattern, so the weft slope of the semi-finished product must be low to ensure the regularity of the printing pattern.
6. The requirements for washing after printing are high. Unlike water washing after dyeing, after printing, the original paste should be removed by water washing to restore the feel of the fabric and remove floating colors to improve the color fastness of the product. Dyeing products require uniform color, while printed products require clear flowers, bright colors and clear outlines. In the water washing process after printing, the floating colors of dyes of different colors are washed and entered into the washing liquid together, which easily causes the fabric to be stained in white and the color is not pure, that is, stained. Therefore, the main points of water washing quality control are: strengthen water washing, remove the original paste and floating color, prevent water washing from staining, and protect the strength of the fabric.
Therefore, engaging in printing work has a wide range of knowledge, high technical content, difficult quality control, and strong challenges. It requires Cotton Printed Fabric Factory to have a strong sense of quality, rigorous work attitude, a high degree of global concept and Strong professional theory and professional skills.