How did Sodium Tripolyphosphate act on detergent?

As we know,there are many raw materials been used in detergent,such as Surface active agent, whitening agent, anti - reprecipitation agent, fluorescent whitening agent, essence, etc.The main raw material is Surface active agent and detergent auxiliary .

Sodium Triplyphosphate,as the auxiliary of detergent,take the function of taking of the Ca and Mg,to improve the surface active,and also,could buffer PH ,soften,disperse and reprecipitation.