add 100 kg of phenethylphenol into the reaction kettle, heat to 50 ℃, add 9 kg of 50% lye, continue to raise the temperature to 120 ℃, and dehydrate under reduced pressure. After dehydration for 10 min, raise the temperature to 140 ℃ to remove the water. Then replace the air in the kettle with nitrogen and slowly add 364 kg of ethylene oxide, react at 150~160 ℃, 0.05~0.15 MPa for about 2 h, and stop the reaction when the pressure no longer drops. The cloud point is measured by sampling. When the cloud point reaches 102~102.5 ℃, the reaction is terminated, the temperature is reduced to about 80 ℃, and the pH value is adjusted to 5.0~6.0 with glacial acetic acid.