Bringing self-healing ability to high pressure laminates through surface modification

To stay competitive, the wood industry has to innovate and develop new surface protectivesystems for wood and wood based products. Many applications of wood products aredetermined by this special surface properties, which are influenced by the nature of surfacematerial, processing parameters and usage conditions.High-pressure decorative laminates (HPL) are a practical solution for horizontal or verticalsurfaces that require high physical, mechanical and chemical performances, with a highversatility and excellent decoration ability. However, durability and reliability of the polymericlayer is still problematic because these materials are susceptible to induced damage whenexposed to critical conditions or long-term use, and may develop microcracks with negativevisual impact. A possible solution for this problem may be development of HPL with self-healingproperties that it has the ability to regenerate microcracks independently of their location.The aim of this work was study the self-healing performance of a commercial polyurethanedispersion (PUD). The commercial PUD was applied as a coating on a finished HPL (like aregular varnish), as a coating on melamine impregnated paper and then pressed (1st bath ofpaper: melamine resin, 2nd bath: PUD) and as an overlay paper impregnated with PUD andthen pressed. HPL were scratched by a steel wool and a knife. Buchholz hardness was studiedtoo. The best self-healing performance occurred for "varnish" approached and for steel wooldamage. Buchholz hardness of these HPLs was always lower than in case of a standardmelamine HPL