Kraft lignin wood fiberboards - The effect of kraft lignin addition to wood chips or board pulp prior to fiberboard production

Kraft lignin is a by-product of kraft pulping with great potential as an ad ditive for wood composites. Kraft lignin was added to wood chips prior to d efibration and alternatively to fibers to improve the properties of fiberbo ards. Lignin-wood fiberboards were produced on both laboratory and semi-ind ustrial scale using different methods of adding the lignin and fixing it wi th metal salt solutions. Both wet-formed (hardboards) and dry-formed (MDF) boards were produced. The properties of lignin hardboards without a post-he at-treatment were slightly better than heat-treated control hardboards. Thi s indicates that addition of kraft lignin in combination with a di- or triv alent metal salt can be an economic alternative to heat-treatment of boards . Results for MDFs indicate that boards with improved dimensional stability could be produced at relatively low cost without need of major investments in equipment.