weigh 1.5g urea powder, press it into a cylindrical shape with a tablet press, fix a wire ring on the bottom surface of the sample, coat the bottom side surface and the edge of the top surface with alkyd resin blending paint, only expose the central part of the top surface, hang and dry when the top surface of the sample is coated with urea formaldehyde resin and paint on the bottom surface of the side surface. Control 30 ℃ in the thermostatic bath, put three conical flasks, add 3ml of deionized water respectively, put one sample in each bottle in the thermostatic bath, take out 1ml at regular intervals, dry and weigh the leachate, add the same volume of deionized water at the same time, take 1ml of leachate within 1-8.5h, take 3ml of leachate at 26-27h each time, and measure the integral solubility.