Compreg-type products by furfurylation during hot-pressing

Abstract

Compreg, phenolic resin impregnated veneers cured under high pressure, was developed in the USA during the early 1940s and immediately found use as a replacement for stainless steel in specific niche applications, e.g. pitch propellers and connector plates in the World War II allied air fleet. Similar material is still produced here in Europe under the tradename Panzerholz, which is used in, for example, bulletproof joinery products. This paper presents two materials, similar to compreg, developed within an EU project (Ecobinders). Veneers were impregnated either with furfuryl alcohol (FA) or waterborne furan prepolymer resin with dissolved catalyst and thereafter dried/precured in an oven. The impregnated veneers were glued with FA/lignin adhesive between the plies, and cured in a hot-press under high pressure. The result was in both cases highly densified modified wood products. The products had hardness higher than any known wood species, high dimensional stability and decay resistance. The properties were generally better for the material modified with FA than for the material modified with the prepolymer which, however, had lower weight percentage gains. Kitchen counter-top prototypes were manufactured by laminating medium-density fibreboard with the FA-compregs. The prototypes were tested for surface resistance and the results fulfilled the criteria for the application.