Application of Sodium Hexametaphosphate in Printing and Dyeing Industry

	With the development of economy, people's pursuit of clothes has become more meticulous. The market demand for colored fabrics is no longer a popular product such as ordinary strips, plaids or Oxford cloth, but a high-grade fabric with novel, fashionable and unique characteristics. Dyes are essential in the printing and dyeing industry, and sodium hexametaphosphate dispersant can provide the whole process of covering pretreatment, dyeing, printing and finishing.

( 1 ) Disperse dye should be dissolved in water below 40 ℃ because a large amount of dispersant has been added during the disperse dye manufacturing process. If the temperature is too high, the dispersant will be destroyed, causing the disperse dye to coagulate. Dissolution is more difficult. If the filter is not clean, it is easy to produce color dots.

( 2 ) Disperse dyes are prone to color change when exposed to metal ions. Therefore, iron is not suitable for color paste preparation, and sodium hexametaphosphate water softener should be added.

( 3 ) Disperse dye is relatively stable in weak acid, and alkaline solution is easy to hydrolyze disperse dye and affect color light. Generally, the pH is controlled within the range of 5 - 5.5. If the pH value is lower than 8 or higher than 10, the dye uptake of polyester will be reduced, resulting in staining on cotton fibers. Lactic acid or tartaric acid can be added to the color paste to adjust the pH value.

( 4 ) The original paste should be sodium alginate paste which is neutral and stable in weak acid. In order to improve the scraping effect of color paste, emulsion paste can be added at the same time, but it should not be too much, otherwise it will affect the contour of the pattern.