Proportion of raw materials: raw material specification (solid content) and dosage (kg) Remarks: Formaldehyde 36-37% 1000 Ordinary formaldehyde (commercially available) glue must be an environmentally friendly formaldehyde modifier 99.8% 200 water (use: reduction modifier) 400-600 well water urea 98% 550 commercially available polyvinyl alcohol 2090 developed by Xingtai Ninth Five-Year Wood Development Center. 0% moderate alkali pressure production process: 1. Add 1000 kg of ordinary formaldehyde into the reaction kettle, then add 200 kg of environment-friendly formaldehyde modifier, add 400-600 kg of cold water (the modifier needs to be diluted with water), and start stirring evenly. Add polyvinyl alcohol (2099 or 2299 model) 1 ~ 2 kg, add 550 kg of urea, and start to heat up. (no need to adjust the PH value). 2. Stop heating at about 55℃ ~ 70℃ (the stop temperature is that the solution in the reaction kettle can self-heat to about 95℃), then self-heat to about 95℃ and react for 75 minutes without adjusting the PH value. 3. Reduce the temperature from 95℃ to 87℃, and then adjust the acid to PH 4.8. /kloc-after fogging in 0/8℃ ~ 20℃ water, when there are fine lines in the fog, immediately press the alkali to PH 7.5. Gelation at 90℃. 4. Cool to 45℃. During this period, the PH value should be well controlled, generally between 7.0 and 7.5. Appearance milky white mucus remarks viscosity 0.25 ~ 0.4 Pa. S free formaldehyde content : 50% storage period > 30 days 5. Matters needing attention: ① acid adjustment: 20% ammonium chloride solution, about 20 kg. Alkaline pressure: 30% sodium hydroxide solution is about 10kg (based on the increase of PH value from 4.8 to 7.5). (2) Temperature: 18℃ ~ 20℃ After the mist rises in water, when there are tiny filaments in the mist, immediately press the alkali to PH 7.5. Generally, alkali pressure is not needed after fog-free, and obvious filaments appear at this time. ③ Hint: The amount of acid and alkali used in this process is more than that in the general process, so more alkali should be used and mixed when pressing alkali.