Sodium tripolyphosphate (STPP) is a solid inorganic compound used in a large variety of household cleaning products, mainly as a builder, but also in industrial cleaning processes and ceramics manufacture.

STPP is widely used in regular and compact laundry detergents (powder, liquid, gel, tablets), automatic dishwashing detergents (powder, liquid, gel, tablets), toilet cleaners, and surface cleaners, and provides a number of functions including sequestration of “water hardness” enabling surfactants to function effectively, pH buffering, dirt emulsification and prevention of deposition, hydrolysis of grease, and dissolving-dispersing dirt particles.

Properties

Melting point: 622 °C

Density : 2.52 g/cm3 (20℃)

vapor pressure : < 0.1 hPa (20 °C)

Storage temperature : no restrictions

solubility H2O: may be clear to slightly hazy

form : Powder/Solid

color: White

pH : 9.0-10.0 (25℃, 1% in H2O)

Water Solubility : 20 g/100 mL (20 ºC)

CAS : 7758-29-4