Background and overview[1][2]
Benzoguanamine is an important chemical raw material widely used in the production of coatings, plastics, and insulation materials. Melamine, commonly known as melamine and protein, is a triazine nitrogen-containing heterocyclic organic compound that is used as a chemical raw material. It is a white monoclinic crystal, almost odorless, slightly soluble in water (3.1g/L at room temperature), soluble in methanol, formaldehyde, acetic acid, hot ethylene glycol, glycerin, pyridine, etc., insoluble in acetone, ethers, and harmful to the body Hazardous and not to be used in food processing or food additives.
Preparation[1]
Due to the increasingly stringent requirements for material quality and standards, the purity requirements for benzomelamine are also getting higher and higher. However, there are currently few reports on the production methods of benzomelamine at home and abroad.
The Chinese invention patent with application number 200610028362.7 discloses a production method of benzinated melamine, which uses high-purity dicyandiamide and benzonitrile as raw materials and inorganic salts as catalysts in an alkanol solvent. The product was washed with water several times, dewatered, dried, and screened to obtain a white crystalline powder product. The benzinated melamine produced by this method has good yield and content, and the product quality is excellent.
However, in the production process of this patented method, the unreacted raw materials dicyandiamide and benzonitrile will be hydrolyzed under strong alkali conditions to form biuret, benzamide, and benzoic acid. The benzoic acid will immediately react with the system. The condensation of alcoholic solvents produces equivalent benzoic acid esters. Therefore, the organic components in the wastewater generated during the production process include benzoguanamine, melamine, benzamide, biuret, benzoate esters, etc. The organic matter in these wastewater is eventually discharged to the sewage treatment station after the washing process, resulting in a huge amount of benzinated melamine sewage and high wastewater treatment costs.
CN201610629015.3 provides a new production method of benzoguanamine. This method uses traditional methods to prepare crude benzoguanamine, and then improves the subsequent purification steps. It not only has a high conversion rate of raw materials and high purity of the resulting product, but also It can effectively recover unreacted raw materials in the production process of benzoguanamine, thereby significantly reducing the types of organic matter and COD in the wastewater after the reaction.
In order to achieve the above objectives, the new production method of benzoguanamine designed by the present invention includes the following steps:
1) Add a certain amount of alkanol as a solvent to the reaction vessel, then add benzonitrile and dicyandiamide, and heat to 110~130°C to fully react with the inorganic base as the catalyst;
2) Heat and evaporate the reactants, evaporate 50-80% of the total weight of the solvent added, and cool the remaining evaporated materials to below 40°C;
3) Add dilute acid solution to the reactant to neutralize it to neutrality or weak alkalinity, and then filter it;
4) The filtrate obtained from the suction filtration treatment in step 3) is left to stand, and the upper organic phase is recovered by liquid separation to obtain unreacted benzonitrile and alkanol solvent;
5) Transfer all the solids obtained by suction filtration in step 3) into a container, add pure water 1 to 3 times the volume of the solids, heat to 95 to 100°C, evaporate at constant temperature for 1 to 3 hours, and then pump while hot Filter;
6) Add the solid obtained by suction filtration in step 5) to 1 to 3 times the volume of hot water and wash it with water. The hot water temperature is 60 to 80°C, and then suction filtrate again to obtain the solid;
7) Dry the solid obtained by suction filtration again and pulverize it to obtain fine benzinated melamine.
Apply[3]
CN201610431456.2 discloses a melamine-formaldehyde resin glue and its internal plastic preparation process. The pH value of the formaldehyde solution is adjusted to 8-9.5 with alkali solution, melamine is added, and the molar ratio of formaldehyde to melamine in the formaldehyde solution is 2 -3, stir and raise the temperature to 40-60°C, and keep it warm for 20-40 minutes; then add benzoguanamine and formaldehyde solutions. The molar ratio of formaldehyde to benzoguanamine is 2-3. Use alkali to adjust the pH. The molar ratio of melamine is (1-3):9, raise the temperature to 80-90°C, maintain a constant temperature, adjust the solution with alkali solution to keep the pH value between 8-9.5, and terminate the reaction when the water dilution reaches 1-2. In the present invention, benzomelamine is introduced into the polymer, and the synthesized copolymer resin has excellent toughness, good hardness, and thermal stability, and can be widely used in impregnated patches.Tissue paper, fireproof board and other fields.
CN201610436381.7 discloses a quaternary copolymerized melamine impregnated resin glue and its preparation method. The pH value of the formaldehyde solution is adjusted with alkali solution, urea and melamine are added in sequence, stirred and heated to 40-60°C, and kept warm for 10-40 minutes; Add melamine, benzoguanamine and formaldehyde solutions again, raise the temperature to 80-90°C and maintain a constant temperature. Measure the reaction solution every 5 minutes, adjust with alkali solution to maintain the pH value of 8-9.5, and terminate the reaction when the water dilution reaches 1-2. The resin synthesized by the invention has excellent toughness, good hardness, thermal stability, and good economic benefits, and can be widely used in impregnated paper decorative panels, paper decorative panels and other fields.
Main reference materials
[1] CN201610629015.3 New production method of benzinated melamine
[2] CN201621021495.7 A high-efficiency washing equipment for benzinated melamine
[3] CN201610431456.2 A kind of melamine formaldehyde resin glue and its preparation process by internal plastic method
[4] CN201610436381.7 A quaternary copolymerized melamine impregnated resin glue and its preparation method
