Abstract

Melamine-based resins [MF, MUF, MUPF, PM(U)F] used as wood adhesives represent one of the largest groups of aminoplastic resins. They are made by the reaction of formaldehyde with melamine using urea, phenol, or other components as comonomers. The hardened resins show duroplastic hardening behavior; they are three-dimensionally cross-linked and hence insoluble, nonmeltable networks. Analytical methods to determine the chemical identity of the complex mixtures (ie, nmr spectroscopy, ir spectroscopy, hplc, as well as mass spectrometry) are described in this article. Melamine-based resins show higher hydrolysis resistance compared to UF resins. The field of application comprises the production of wood-based panels such as particleboards, MDF, OSB, plywood, blockboards, and others especially for use under humid conditions. The molar ratio between formaldehyde/reactive amino groups [F/(NH₂)₂] distinctly determines reactivity, the degree of cross-linking, and hence the bonding strength. Cocondensation between melamine, formaldehyde, and other components (such as urea and phenol) is possible, furnishing cocondensates with improved properties and reduced price.

The possiblity of increasing the impact strength of MF resins using rubber toughening technology is examined.