Water Treatment Agent
Industrial sequestering agents are added to textile process water to bind dissolved alkaline earth metal ions that interfere with detergent performance. In wet processing and dyeing of bast fibers, sodium hexametaphosphate acts as a highly effective inorganic polyphosphate chelator and dispersant. This chemical compound prevents the formation of insoluble calcium and magnesium soaps that can deposit on flax fibers.
Its utility is bounded by high temperatures where it slowly hydrolyzes into simple orthophosphates, losing its sequestering power.
Metal Chelation
The molecular structure of this sodium salt consists of a ring of six phosphate units that coordinate with polyvalent metal ions to form soluble complexes. This sequestering action by sodium hexametaphosphate prevents the metal ions from reacting with anionic surfactants during scouring. Additionally, it helps disperse natural waxes and dirt particles, keeping them suspended in the bath.
This dispersion prevents the redeposition of contaminants onto the cleaned yarn or fabric, ensuring a high degree of whiteness after bleaching.
Scouring Application
In Chinese flax mills, the compound is added to the initial boiling bath during alkaline scouring. This addition improves the hand feel and uniformity of the subsequent dye uptake. Fabric rejects due to uneven bleaching are reduced.
