Thermosetting adhesive formed by polycondensation of melamine or melamine urea and formaldehyde under the action of catalyst. Also known as melamine formaldehyde resin glue. Include melamine formaldehyde resin glue and melamine urea formaldehyde resin glue. It is an important amino resin. Because of its great activity, it can be cured by heating without adding or adding a small amount of curing agent.

Melamine is a triamino compound. From the chemical structure, it contains groups similar to urea molecules, so it has similar properties to urea. It reacts with formaldehyde to produce hydroxymethyl melamine, and then further polycondensation to produce melamine formaldehyde resin. Its reaction process:

Manufacture of melamine resin: generally 1 mol melamine reacts with 2 ~ 3 mol formaldehyde in alkaline or neutral medium at 80 ~ 90℃ to prepare water-soluble or water-soluble melamine resin.

Table 1

Table 2

Table 3 Melamine itself has a high melting point, and the adhesive has a high degree of crosslinking after curing, so the product has good thermal stability, hardness, wear resistance, boiling water resistance and chemical resistance. However, after curing, the adhesive layer is fragile, the product is easy to break, and the stability of pure resin is poor. Generally, modified melamine resin adhesive is not used alone.

Melamine resin adhesive is widely used in the production of paper-plastic veneers and outdoor man-made boards. As an adhesive, melamine is usually condensed with urea and formaldehyde; The method of mixing melamine resin with urea-formaldehyde resin or adding melamine monomer into urea-formaldehyde resin. See table 1, 2, 3 for the relationship between ratio and performance.