Formaldehyde-free amino resins on a glycol aldehyde basis for wood-based materials and decorative paper coatings

Project start / September 01, 2015

Simply reducing the formaldehyde content in adhesives for wood-based materials and impregnation resins does not seem to suffice – resins which are completely free of formaldehyde are, in fact, required. In this project, we are developing formaldehyde-free melamine and melamine-urea resins on a glycol aldehyde basis for use as adhesive in wood-based materials and as impregnation resin for decorative paper coatings. The idea is to introduce these new resins without any need for changes to the established processing conditions and without any detriment to the product properties. The manufacturing price should be comparable to the currently used formaldehyde-based amino resins.

Last modified: September 01, 2015

© Fraunhofer WKI
Shavings, formaldehyde-free melamine resin and the finished board (in the background)

Adhesives for wood-based materials have to be sufficiently available, not harmful to health or environment, and technically and economically competitive. To achieve these goals, we are using carbohydrate aldehydes (glycol aldehyde and glyceraldehyde) instead of formaldehyde to manufacture formaldehyde-free amino resins. By developing these new resins and optimizing their properties for the industrial production of wood-based materials and decorative paper coatings, we seek to reduce formaldehyde emissions to the level released only by the wood itself.

Our aim is to completely replace formaldehyde in the amino resins (urea formaldehyde [UF], melamine urea formaldehyde [MUF] and melamine formaldehyde resins [MF]) used in over 90% of wood-based materials and decorative paper coatings with new carbohydrate aldehydes (glycol aldehyde). We manufactured particle board in a preliminary test using melamine glycol aldehyde resin and assessed its mechanical and hygric properties.

Table 1: Mechanical and hygric properties of 13mm-thick particle board containing melamine glycol aldehyde resin (MG) and UF resin as a reference

Resin	Press duration	Board characteristic
Resin	Press duration	Density	Bending strength	Bending modulus of elasticity	Transverse tensile strength	Thickness swelling 24h
	s/mm	kg/m³	N/mm²	N/mm²	N/mm²	%
MG-Harz	15	682	12,0	3023	0,32	20,9
MG-Harz	22	703	11,9	3156	0,30	21,8
UF-Harz	22	711	12,3	2738	0,45	20,1
DIN EN 312:2010 (Typ 2)			≥ 11	≥ 1600	≥ 0,35	No requirement