A preparation method of modified urea-formaldehyde glue for moisture-proof and environment-friendly MDF
A technology for modifying urea-formaldehyde and MDF, applied in the direction of adhesives, aldehyde/ketone condensation polymer adhesives, adhesive types, etc., can solve the problem that MDF cannot pass the moisture-proof performance test, etc., to enhance physical mechanics Good performance, good water resistance and precise endpoint control
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Embodiment 1
[0020] Formaldehyde 100 parts (concentration 37%), urea 70 parts, melamine 5.5 parts, the preparation method is as follows:
[0021] ① Put 100 parts of formaldehyde aqueous solution into the reaction kettle, start the agitator, start heating up, stop heating when the temperature rises to 47°C, and adjust the pH value to 1.5 with industrial hydrochloric acid with a mass concentration of 27%.
[0022] ② When the temperature is stable at 50°C, add 23 parts of the first batch of urea evenly, and control the final temperature at 70-74°C to end the reaction.
[0023] ③ Slowly add 25-30% sodium hydroxide aqueous solution to adjust the pH to 3.8, the temperature is 76°C, add 5.5 parts of melamine and heat up and stir for 15 minutes, when the temperature reaches 87°C, add the second batch of urea 12 parts, the temperature is 86 Keep at -88°C for 25 minutes, drop the reactant into water at 45°C, and the white cloud is the first end point.
Embodiment 2
[0033] 110 parts of formaldehyde (concentration 37%), 65 parts of urea, 4.1 parts of melamine. Its preparation method is:
[0034] ① Put 110 parts of formaldehyde aqueous solution into the reaction kettle, start the agitator, start heating and heating, stop heating when the temperature rises to 47°C, and adjust the pH value to 1.8 with industrial hydrochloric acid with a mass concentration of 31%.
[0035] ② When the temperature is stable at 49°C, add 24 parts of the first batch of urea evenly, and control the final temperature to 80°C to end the reaction.
[0036] ③ Slowly add 25-30% sodium hydroxide aqueous solution to adjust the pH to 4.8, raise the temperature to 85°C, add 4.1 parts of melamine to raise the temperature and stir for 20 minutes, when the temperature reaches 89°C, add 11 parts of the second batch of urea, and keep the temperature at 88-92 The temperature was maintained at ℃ for 15 minutes, and the reactant was dropped into water at 40 ℃, and the white cloud ...
Embodiment 3
[0046] (1) Formaldehyde 120 parts (concentration 37%), urea 63.8 parts, melamine 4.9 parts. Its preparation method is as follows:
[0047] ① Put 120 parts of formaldehyde aqueous solution into the reaction kettle, start the stirrer, start heating up, stop heating when the temperature rises to 43°C, and adjust the pH value to 2.0 with industrial hydrochloric acid.
[0048] ② When the temperature is stable at 49°C, add 21.4 parts of the first batch of urea evenly, and control the final temperature to 65°C to end the reaction.
[0049] ③ Slowly add 25-30% sodium hydroxide aqueous solution to adjust the pH to 4.6, raise the temperature to 80°C, add 4.9 parts of melamine to heat up and stir for 25 minutes, the temperature is 82°C, add the second batch of 13.3 parts of urea, and keep at 88-92°C Keep it for 20 minutes, drop the reactant into water at 45°C, and the white cloud is the first end point.
[0050] ④ Add 25-30% sodium hydroxide aqueous solution to adjust the pH to 6.3, ad...
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