Preparation method and application of modified polysiloxane polyol

The invention relates to a preparation method of polyhydric alcohol, in particular to a preparation method and application of modified polysiloxane polyhydric alcohol. Comprising the following steps: (1) adding a phenolic compound and an alcohol amine compound into a kettle, and carrying out a heating reaction; (2) after reacting for a certain time, adding a certain amount of epoxypropane to continuously react, reacting for a certain time, adding a basic catalyst, adding polyether modified polysiloxane, and carrying out nitrogen displacement; (3) controlling the temperature in the reaction kettle, adding epoxypropane for the second time, reacting for a certain time, and removing unreacted residual monomers; and (4) carrying out post-treatment and refining to obtain a polyether polyol product. According to the preparation method, polysiloxane, a phenolic compound and an alcohol amine compound raw material composite initiator are matched to play a synergistic effect, so that the emulsion reaction efficiency of