In the history of detergents, phosphates, silicates and carbonates have always been important detergent builders. Especially sodium tripolyphosphate stpp powder, which is considered to be an detergent auxiliary agent that acts close to surfactants, for that it has the excellent functions of good ability to chelate hard water, emulsification, dispersibility and PH buffering. However, with the emergence of phosphorus-rich water bodies in some areas, causing redness, the voice of phosphorus-free detergents is getting higher and higher, which has set off a climax in the development and application of phosphorus-replacement additives.
There are two directions for the development of phosphorus replacement additives. One is the development and application of new integrative agents, such as the combined application of sodium metasilicate and sodium sodium carbonate, sodium tritrimidine and sodium ethylenediaminetetraacetate, and the other is the use of ion exchangers.
Phosphates used in detergents include orthophosphate and polymeric phosphate, but the main one are polymeric phosphate, especially sodium tripolyphosphate detergent builder. Other polymeric phosphates, such as sodium pyrophosphate and sodium hexametaphosphate are easy to absorb moisture and should not be mixed into detergent powder. They can be only used in some special processes.
Phosphates can chelate hardening metal ions(mainly calcium and magnesium ions) in water to make them soluble compounds, thereby softening water. SHMP chemical has the strongest chelating ability to calcium ions, while tetrasodium pyrophosphate has the strongest ability to magnesium ions. The chelating ability of stpp chemical to calcium and magnesium ions is between the above two phosphates. Phosphates can also re-dissolve the insoluble calcium and magnesium salts and the insoluble calcium soap and phosphate remianing in the previous washing process contained in the fiber, thereby increasing the detergency of the detergent. In addition, it can also peptize insoluble substances and maintain a suspended state, can also emulsify oily substances.