Organic silicon modified alkynol defoaming agent and preparation method thereof

The preparation method comprises the following steps: putting hydrogen-containing silicone oil and alkynol into a reaction kettle, heating to 75-85 DEG C for the first time, vacuumizing under the negative pressure of less than or equal to-0.09 MPa for 25-35 minutes, and stopping vacuumizing; adding nitrogen, adding a catalyst, heating to 100-125 DEG C for the second time, keeping the temperature for 2-5 hours, and cooling to obtain an organic silicon modified alkynol defoaming agent intermediate; mixing the organic silicon modified alkynol defoaming agent intermediate, a solvent and an emulsifier, heating and uniformly stirring to obtain the organic silicon modified alkynol defoaming agent. The carbon chain number of alkynol is 6-12, and the hydroxyl number is 4, 6 or 8. According to the invention, a micromolecular alkynol chain segment and a macromolecular organosilicon chain segment are combined through hydrosilylation, and the respective advantages of micromolecular alkynol and hydrogen-containing silicone