Circular production of hexamethylolmelamine

Abstract

Disclosed is a process of cyclically producing hexamethylolmelamine, comprising: adding a mother liquid and high-concentration formaldehyde aqueous solution in a hydroxylation reaction kettle; stirring and heating the solution in the kettle; adding alkali in the reaction kettle, and pre-adjusting a pH value of the solution in the kettle; then adding melamine in the reaction kettle; adding alkali again into the reaction kettle, and adjusting the pH value of the solution in the kettle; raising a temperature of the reaction solution in the kettle for reaction; introducing the solution in the kettle which has already been cooled into a centrifuge for centrifugal separation to obtain hexamethylolmelamine wet material and the mother liquid; delivering the hexamethylolmelamine wet material to a drying system for subsequent drying; returning the mother liquid back to the reaction kettle; and repeating the above steps for cyclic production. By using high-concentration formaldehyde, the present disclosure enables the mother liquid to be cyclically used for a production procedure, thereby substantially reducing the product costs and achieving zero-pollution emission.

Description

technical field [0001] The invention relates to a new environment-friendly production process of hexamethylolmelamine. Background technique [0002] Hexamethylolmelamine is used in the rubber adhesive industry to react with alcohols to produce rubber adhesive A, which is widely used in strengthening the bonding of rubber and cords. Etherified products can also be used in coil coatings and automotive coating additives. [0003] At present, the production of hexamethylol melamine generally adopts melamine and 37% formaldehyde aqueous solution or paraformaldehyde as raw materials to carry out methylolation reaction under alkaline conditions, and the product is obtained after dehydration and drying. The problems that all exist in these technologies are that there are many aldehyde-containing wastewaters and great pollution, and the mother liquor after separation and dehydration is in a paste state, which is not conducive to the recycling of the mother liquor. In addition, the ...

AI Technical Summary

Problems solved by technology

The problems existing in these technologies are that there are many aldehyde-containing waste water and great pollution, and the mother liquor after separation and dehydration is in the form of paste, which is not conducive to the recycling of the mother liquor

In addition, the filter cloth is easily blocked during centrifugation, which is not easy to clean, and a large amount of formaldehyde-containing washing wastewater is generated during cleaning, which cannot be effectively recycled or treated.

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