1. Formaldehyde-based thermosetting adhesives and binders

1.1 Urea formaldehyde (UF) adhesives and binders

UF adhesives and binders are produced by the chemical reaction of formaldehyde – or formaldehyde – with urea, as shown in figure 1 .

In the first stage, urea and formaldehyde react in an aqueous acid medium.

Formalin/urea ratios, pH and temperature can be varied. In general, however, an excess of formaldehyde is used, so that the molecules are terminated by methylol groups.

The reaction is stopped when the desired viscosity is reached, and the glue is delivered to the user.

The second step, at the end-user's, is to add a catalyst to...