Preparation method for synthesizing polysiloxane neutralizing agent by using alkaline process

The invention relates to a preparation method for synthesizing a polysiloxane neutralizing agent, and particularly relates to the preparation method for synthesizing the polysiloxane neutralizing agent by using an alkaline process. The neutralizing agent can be used for neutralizing dimethyl siloxane different in viscosity. The preparation method comprises the following detailed steps: adding phosphoric acid and hydroxyl blocked siloxane which has dimethyl siloxane links into a reaction container, stirring and heating, controlling the temperature and dehydrating until the mixture is transparent, wherein silicon-based phosphate with different viscosities can be prepared by regulating the dehydration time. The silicon-based phosphate is used as the neutralizing agent for alkaline-process polymerization, and the neutralization time is shortened by 65%-95% in comparison with the conventional neutralization time; moreover, the preparation method is simple in preparation process, convenient to operate and easy to popularize and industrialize, also has an excellent neutralization effect and can be used for remarkably improving the thermal stability of polysiloxane.