Preparation method for propyl silicate waterproof agent

The invention discloses a preparation method for a propyl silicate waterproof agent and belongs to the technical field of waterproof agents. According to the preparation method disclosed by the invention, a by-product, namely, propyltrichlorosilane in a process for producing a silane coupling agent, namely, gamma-chloropropyl trichlorosilane, is reacted with methanol in a molar ratio of 1: (3 to 5) to prepare propyltrimethoxysilane, then the propyltrimethoxysilane is hydrolyzed to obtain propylsilanol, and the propylsilanol is reacted with strong base under the suppression protection of methanol to prepare the propyl silicate aqueous solution-type waterproof agent. The preparation method disclosed by the invention is simple in preparation process, short in reaction time, and adequate in reaction; the yield of propyl silicate is greater than 75%; the generation of wastewater and solid wastes in the preparation process is avoided, so that pollution to environment is avoided.