Preparation method of powdery lignin modified urea resin
The technology of urea-formaldehyde resin and lignin is applied in the field of preparation of powdery lignin-modified urea-formaldehyde resin, which can solve problems such as excessive formaldehyde emission and no powdery modified urea-formaldehyde resin, and achieve long storage period and save petrochemical industry. Raw materials, the effect of reducing production costs
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Embodiment 1
[0037] Embodiment 1 contains the sulfomethylation modification of lignin raw material
[0038] (1) Make raw materials containing lignin into an aqueous solution with a concentration of 0.1g / ml-0.4g / ml, and then adjust the pH value to 9-11 with alkali or alkaline salt;
[0039] (2) Heating to 70°C-80°C, adding 20%-60% of the lignin mass in the raw material and adding formaldehyde with a concentration of 37% and stirring at constant temperature for 2-3 hours;
[0040] (3) Add Na with 30% to 70% of the lignin mass in the raw material 2 SO 3 , adjust the pH value to 7-8 with acid or acid salt, react at 100°C-140°C for 3-4h, and then cool the reaction solution;
[0041] (4) Dry the reaction solution prepared in step (3) and pulverize it.
[0042] In the above method, the raw material containing lignin may be crude lignin, refined lignin, corn straw preparation energy alcohol residue or papermaking black liquor residue, etc.
Embodiment 2
[0043] Example 2 Preparation of powdery lignin modified urea-formaldehyde resin
[0044] Add 900g of formaldehyde (37%), add alkaline to adjust the pH value to 8-8.5, add 320g of urea, heat in a water bath at 90°C, add the first batch of melamine 10g, and react for 30mins. Cool down to 80°C, add 155g of the second batch of urea, adjust the pH to 5.6, add 193g of sulfomethyl-modified industrial lignin containing 70% (crude lignin), and react for 30mins. Add acid to adjust the pH to 4.8, react for 70 minutes, wait for the viscosity (measured at -4 cups at 25°C) to be about 22 seconds, adjust the pH to 6.2, lower the temperature to 70°C, add the third batch of urea 100g, and react for 30mins. Cool down to 59°C, add the fourth batch of urea 75g, the second batch of melamine 19g, react for 30mins, adjust the pH back to 7.5, cool down to below 50°C, and discharge to obtain a tan product. The viscosity of the glue is 19-27 seconds (Tu-4 cups measured at 25°C), after stirring evenly,...
Embodiment 3
[0045] The preparation of embodiment 3 powdery lignin modified urea-formaldehyde resin
[0046] Formaldehyde (37%) 600g, add alkaline to adjust the pH value to 8-8.5, throw urea 210g, heat in water bath at 90°C, add the first batch of melamine 7g, react for 30mins; cool down to 80°C, add the second batch of urea 35g, adjust the pH Adjust to 6.0, add 80g of sulfomethyl-modified corn stalks containing 30% lignin to prepare energy alcohol residue, and react for 30mins. Add acid to adjust the pH to 4.7, react for 70 minutes, and wait until the viscosity (measured at 25°C with -4 cups) is about 24 seconds. Adjust the pH to 5.8, lower the temperature to 70°C, add the third batch of urea 80g, and react for 30mins. Cool down to 59°C, add 70g of the fourth batch of urea, 13g of the second batch of melamine, react for 30mins, adjust the pH back to 7.5, cool down to below 50°C, and discharge to obtain a tan product. The viscosity of the glue is 21 seconds to 23 Seconds (measured at -4 ...
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