Wood particle mixture for a wood-plastic composite material and method for producing the wood particle mixture

Abstract

A wood particle mixture is described especially made from raw wood for an extruded or injection-molded wood-plastic composite material, especially manufactured from wood-plastic compound, which significantly improve the strength properties in a wood plastic composite material. Each wood particle has certain dimensions and certain shaping.

1 . A wood particle mixture, for an extruded or injection-molded wood-plastic composite material, comprising a plurality of wood particles characterized in that each wood particle has two cut surfaces, which define its thickness and which run approximately in the direction of its grain, and each wood particle has at least one of cut edges or fracture edges defining its length in the direction of the grain and also its width perpendicular to the direction of the grain.  
     
     
         2 . The wood particle mixture according to  claim 1 , which is formed of raw wood.  
     
     
         3 . The wood particle mixture according to  claim 1 , characterized in that at least 90 wt % of the wood particles have a thickness between 0.2 mm and 2.0 mm and also a length and a width up to 8.0 mm.  
     
     
         4 . The wood particle mixture according to  claim 1 , characterized in that at least 90 wt % of the wood particles have a thickness between 0.2 mm and 1.4 mm and also a length and a width up to 2.5 mm.  
     
     
         5 . The wood particle mixture according to  claim 1 , characterized in that the cut surfaces running in the direction of the grain are arranged approximately parallel to each other.  
     
     
         6 . The wood particle mixture according to  claim 1 , characterized in that each wood particle consists of spruce wood.  
     
     
         7 . The wood particle mixture according to  claim 1 , characterized in that each wood particle consists of loblolly pine wood.  
     
     
         8 . The wood particle mixture according to  claim 1 , with a moisture content of less than 15% relative to absolute dry mass.  
     
     
         9 . The wood particle mixture according to  claim 1 , with an extract content of less than 5.5% relative to absolute dry mass.  
     
     
         10 . A composition comprising a plastic mixed with the wood particle mixture of  claim 1 .  
     
     
         11 . An article of manufacture extruded or injection molded from the composition of  claim 10 .  
     
     
         12 . Method for producing a wood particle mixture for an extruded or injection-molded wood-plastic composite material comprising generating flat chips of wood from the raw wood by at least one blade, cutting the flat chips into smaller pieces, breaking the cut-up flat chips into flat splinters, and filtering the flat splinters according to size.  
     
     
         13 . The method according to  claim 12 , wherein the flat chips are generated by means of blades placed parallel to the grain of the raw wood.  
     
     
         14 . The method according to  claim 12 , further comprising leading the flat chips into a wet bunker feeding the flat chips from the wet bunker by a vibrating flat channel to at least one cutting mill with filter passage, suctioning off the cut-up flat chips from the cutting mill by air leading chips into a wet cyclone and separating the chips from the air stream, leading the cut-up flat chips from the wet cyclone by a dosing bunker into a dryer, through which dryer the chips are suctioned by air, leading the cut-up and dried flat chips from the dryer into a drying bunker, from bunker the chips are supplied to a hammer mill with at least one filter passage, in which they are broken up into flat splinters, suctioning the flat splinters from the hammer mill, leading the chips into a drying cyclone, and separating the chips from the air stream, and leading the flat splinters from the drying cyclone into a filtering device, in which flat splinters lying in a predetermined range of sizes for the wood particle mixture are filtered out and flat splinters lying above the predetermined range of sizes are fed back into the drying bunker.  
     
     
         15 . The method according to  claim 14 , characterized in that the flat splinters, which were filtered by the filtering device and which lie in predetermined range of sizes, are fed to a wobble sieve and there flat splinters lying below the predetermined range of sizes for the wood particle mixture are separated.  
     
     
         16 . The method according to  claim 12 , characterized in that the flat chips are cut up in undefined directions.  
     
     
         17 . The method according to  claim 12 , characterized in that extracts are washed out from the raw wood and/or the flat chips and/or the cut-up flat chips and/or the flat splinters and/or the wood particle mixture.  
     
     
         18 . The device for performing the method according to  claim 12 , characterized in that the filtering device has at least two flat sieves arranged one after the other with different mesh widths.  
     
     
         19 . The device according to  claim 18 , characterized in that the first flat sieve has an open mesh width between 2 mm and 4 mm.  
     
     
         20 . The device according to  claim 18 , characterized in that the second flat sieve has an open mesh width between 0.5 mm and 1.0 mm.  
     
     
         21 . A cutting mill having an input and an output side and having the output side at least one filter passage, which is formed as an elongated hole filter, whose elongated holes have a length between 40 mm and 70 mm and a width between 3 mm and 8 mm.  
     
     
         22 . A hammer mill having an input and an output side and where the output side has at least two different alternating filter passages, which are formed as elongated hole filters, wherein the elongated holes of one of the filter passages exhibit approximately twice the width of the elongated holes of the other filter passage.  
     
     
         23 . The hammer mill according to  claim 22 , characterized in that the elongated holes have a length between 10 mm and 50 mm and a width between 0.5 mm and 2.5 mm.  
     
     
         24 . The hammer mill according to  claim 22 , characterized in that all elongated holes have a spacing between 0.5 mm and 5.0 mm relative to each other.  
     
     
         25 . The cutting mill of  claim 21 , characterized in that all elongated holes have a spacing between 0.5 mm and 5.0 mm relative to each other.  
     
     
         26 . A device for performing the method according to  claim 12 , characterized in that the blade has a length between 15 mm and 25 mm.  
     
     
         27 . A device for performing the method according to  claim 12 , characterized in that the blade is set such that the ratio of the cutting speed divided by the advancing speed is between 550 and 750.