Application of Sequestering Agent in Printing and Dyeing

1. The printing and dyeing industry of water treatment requires soft water except for individual processes

The sequestering agent has the effect of softening water quality to sequester the metal ions in the water during the water softening process.

2. Desizing

Usually, heavy metal compounds are added to the sizing of the fabric as spinning agents, such as zinc salts, copper sulfate and organic copper-containing compounds. But these compounds are not conducive to enzyme desizing. With the sequestering agent, the sizing agent is easier to puff, detach from the fiber, decompose and remove the colloidal state, and can prevent impurities and slurry from depositing on the fiber again, which can make the base fabric whiter and safer to desizing.

3. Boiling-off

Adding a sequestering agent in the scouring process can chelate and disperse the calcium and magnesium ions in the scouring liquid, which is beneficial to the removal of pectin and prevents insoluble calcium and magnesium salts from depositing on the fabric, thereby improving the capillary effect and eliminating calcium spots, which greatly improves the scouring effect and the levelness of dyeing.

4. Bleaching

Metal ions contained in fibers and in unsoftened water or Fe3+ in equipment pipes will accelerate the decomposition of hydrogen peroxide, causing textiles in the bleaching process of local excessive oxidation, strength decline, and even holes. The agent can effectively block metal ions, indirectly control the decomposition rate of hydrogen peroxide, and prevent fabric damage. When it is used for washing after bleaching, it can promote the removal of degraded impurities from the fiber surface during bleaching. Because sodium silicate is often used as an oxygen bleaching stabilizer in hydrogen peroxide bleaching, it will produce silica scale after long term use. Thus, the sequester agent can prevent silicate crystals from depositing on the equipment and also make the hard scale that has been generated on the equipment clean.

5. Dyeing

During dyeing, the color is often affected by metal ions in hard water. With the heavy metal ions, the dye decomposition may happen, too. The function of sequestering agent including dispersion, complexation and electrostatic repulsion can help the dye to dissolve, improve its diffusion rate, and make the dye fully and uniformly diffuse and dissolve in the dye solution in a shorter time, so as to dye the fiber. It can also complexate the metal ions and impurities in the dye solution to form a stable complex, reduce the association of dyes, avoid the generation of blemishes and other defects, and indirectly play a leveling role.

6. Polyester alkali reduction

The agent can effectively prevent the accumulation of debris from polluting the equipment.

7. Soaping

Adding an appropriate amount of the sequestering agent during soaping can completely remove the floating color on the surface of the printed and dyed fabric, and make the fabric get better dye fastness. In addition, it can also promote the printing paste to be washed away quickly when the printed product is soaped.

8. Discoloration

When the fabric is not dyed or the dyed flower needs to be peeled off, the sequestering agent will help the fabric to peel off the color and have a better reduction effect.