Method for producing wood-plastic composite material

Abstract

The invention relates to a method for producing a wood-plastic composite material, by which means the composite material is provided with a pre-determined color and pre-determined material characteristics during the course of the method. The method according to the invention is characterized by the drying and treatment of the wood chips using chromophore substances and/or active substances in a fluidized bed appliance during one of the method steps preceding the extrusion. Following the treatment, sorted wood chips can be removed from the fluidized bed within a pre-selected dimension spectrum and extruded with plastic in the subsequent method step.

1 - 7 . (canceled) 
   
   
       8 . A method for producing a wood-plastic composite material, comprising the steps of
 drying wood chips in a fluidized bed apparatus to a residual moisture content below 10%   processing the wood ships by adding color-forming substances and/or active substances,   removing the wood chips from the fluidized bed apparatus, and   feeding the processed wood chips with plastic and to an extruder, producing wood-plastic-composite material.   
   
   
       9 . The method according to  claim 8 , further comprising the step of
 discharging the wood chips from the fluidized bed according to size with a predetermined size distribution.   
   
   
       10 . The method according to  claim 9 , wherein the wood chips are discharged according to size with dimensions of ≧0.1 mm. 
   
   
       11 . The method according to  claim 9 , wherein the wood chips are processed in the fluidized bed apparatus with an excess of color-forming materials and/or active substances necessary for complete coloration and/or penetration of the wood chips. 
   
   
       12 . The method according to  claim 8 , wherein fluidizing in the fluidized bed apparatus is accomplished with a fluidizing gas at a temperature in a range from 40° C. to 100° C., and dried to a residual moisture content in a range from 0.5% to 10%, followed by an injection of color-forming substances and/or active substances into the fluidized bed,
 wherein the wood chips are treated for a time between 10 minutes to 30 minutes at a fluidized bed temperature between 35° C. to 40° C.,   wherein the entry temperature of the fluidizing gas is in a range between 75° C. to 85° C., and wherein the temperature of the fluidized bed is increased to 60° C. to 35° C. for a duration between 2 minutes and 10 minutes for post-drying the wood chips, and   wherein the dried and processed wood chips are removed from the fluidized bed apparatus.   
   
   
       13 . The method according to  claim 8 , wherein the color-forming substances and/or active substances are introduced in the fluidized bed in a liquid dispersed form. 
   
   
       14 . The method according to  claim 12 , wherein the temperature of the fluidizing gas is in a range between 60° C. to 80 20  C. 
   
   
       15 . The method according to  claim 12 , wherein the drying is accomplished to a residual moisture content in the range between 1% to 3%. 
   
   
       16 . The method according to  claim 8 , wherein additional auxiliary substances or additives are added to the processed wood chips and plastic before it is fed to the extruder. 
   
   
       17 . The method according to  claim 14 , wherein the quantity of the color-forming substances injected into the fluidized bed is in a range between 4 mass % and 6 mass %. 
   
   
       18 . The method according to  claim 14 , wherein the quantity of the active substances injected into the fluidized bed is in a range between 1 mass % and 2 mass %.