METHOD FOR PRODUCING MULTI-LAYERED LIGNOCELLULOSE MATERIALS HAVING A CORE WITH SPECIAL PROPERTIES AND AT LEAST ONE UPPER AND ONE LOWER COVER LAYER
Abstract:
The present invention relates to a process for the batchwise or continuous, preferably continuous production of multilayer lignocellulose materials with a core and with at least one upper and one lower outer layer, comprising the following steps: a) mixing of the components of the individual layers separately from one another, b) layer-by-layer scattering of the mixtures (for the core layer and for the outer layers) to give a mat, c) precompaction after the scattering of the individual layers, d) application of a high-frequency electrical field before, during and/or after the precompaction, and then e) hot pressing, where, in step a), for the core, the lignocellulose particles A) [component A)] are mixed with B) from 0 to 25% by weight of expanded plastics particles with bulk density in the range from 10 to 150 kg/m3 [component B)], C) from 1 to 15% by weight of one or more binders selected from the group consisting of aminoplastic resin and organic isocyanate having at least two isocyanate groups [component C)], D) from 0 to 3% by weight of ammonium salts [component D)], E) from 0 to 5% by weight of additives [component E)] and F) from 0.1 to 3% by weight of alkali metal salts or alkaline earth metal salts from the group of the sulfates, nitrates, halides and mixtures of these [component F)], and for the outer layers, the lignocellulose particles G) [component G)] are mixed with H) from 1 to 15% by weight of one or more binders selected from the group consisting of aminoplastic resin and organic isocyanate having at least two isocyanate groups [component H)], I) from 0 to 2% by weight of ammonium salts [component I)], J) from 0 to 5% by weight of additives [component J)] and K) from 0 to 2% by weight of alkali metal salts or alkaline earth metal salts from the group of the sulfates, nitrates, halides and mixtures of these [component K)], wherein, after step a), the mixture for the core comprises, based on the total dry weight of the mixture of components A) to F) from 3 to 15% by weight of water, the mixture(s) for the outer layers comprise(s), based on the total dry weight of the mixture(s) of components G) to K), from 5 to 20% by weight of water, and the following conditions are met: component F)≧1.1•component K) and [component F)+component D)]≧1.1•component K)+component I
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