Ligniinipohjaiset liima-aineet ja menetelmä niiden valmistamiseksi

The invention concerns a lignin and/or carbohydrate-based adhesive binder for fiber boards, particle boards and similar wood-based products, comprising a foamed mixture of an aqueous suspension of lignin and/or carbohydrates obtained from a process of pulping lignocellulosic materials, the mixture being foamed to 1.1 to 10 times the volume of the liquid mixture and the density of the foam being 0.1 to 0.9 kg/l, and the medium foam bubble diameter 0.01 to 0.05 mm. The invention also concerns a method of preparing lignin and/or carbohydrate-based adhesive binders for wood-based products, as well as particle boards, fiber boards or similar wood-based products comprising wood particles, flakes or fibres mixed with the adhesive binder. By foaming the adhesive, an even dispersion of the solids is provided, which improves the quality of the products and gives rise to substantial savings in adhesive use.