Lignocellulose fiber filler for thermoplastic composite compositions

Abstract

A discontinuous lignocellulose fiber is described for use as a reinforcing filler for thermoplastic composite compositions. The fiber filler includes a significant percentage by weight of long, “hair-like” fibers. Specifically, at least about 20 percent by weight of the fiber filler is discontinuous lignocellulose fiber with a fiber length greater than about 15 millimeters and a fiber diameter less than about 0.5 millimeters. A moldable thermoplastic composite composition including the discontinuous lignocellulose fiber comprises about 20 to about 50 percent by weight of the fiber filler and about 50 to about 80 percent by weight thermoplastic. The discontinuous lignocellulose fiber filler yields thermoplastic composite compositions having improved physical properties over basic thermoplastic. The improved physical properties can be achieved without the use of coupling agents, although coupling agents may be used to further enhance the composite properties. The discontinuous lignocellulose fiber is preferably derived from virgin, waste wood from either softwood or hardwood tree species depending on the end use of the composite composition. The thermoplastic can be selected from a number of post-consumer or post-industrial waste sources. Processes for the manufacture of the discontinuous lignocellulose fiber reinforcing filler and the thermoplastic composite compositions are also disclosed.

1 - 12 . (canceled)  
     
     
         13 . A moldable thermoplastic composite composition, comprising: 
 about 20 to about 50 percent by weight of a discontinuous lignocellulose wood fiber filler, the discontinuous lignocellulose wood fiber filler comprising at least (A) about 20 percent by weight of discontinuous lignocellulose wood fibers having a length of at least about 15 millimeters and a diameter of less than about 0.50 millimeters, and (B) a size distribution of the fiber filler as percent by total weight fiber filler withheld on ASTM screens from about 20 to about 50 percent withheld on an 8 mesh screen, about 20 to about 40 percent withheld on a 16 mesh screen, about 20 to about 30 percent withheld on a 50 mesh screen, and about 10 percent finer than a 50 mesh screen, and    about 50 to about 80 percent by weight thermoplastic.    
     
     
         14 . The moldable thermoplastic composite composition as recited in  claim 13 , wherein the thermoplastic is selected from polyethylenes, polypropylenes, polyanimides, polyvinyl chloride, ABS, polystyrene, polyester and mixtures thereof.  
     
     
         15 . The moldable thermoplastic composite composition as recited in  claim 13 , wherein the thermoplastic is derived from post consumer or post industrial waste sources.  
     
     
         16 . The moldable thermoplastic composite composition as recited in  claim 13 , further comprising about up to about 10 percent of a coupling agent.  
     
     
         17 . The moldable thermoplastic composite composition as recited in  claim 16 , wherein the coupling agent is up to about 5 percent maleic anhydride grafted polypropylene, and the thermoplastic is about 45 to about 75 percent polypropylene.  
     
     
         18 . The moldable thermoplastic composite composition as recited in  claim 16 , wherein the coupling agent is up to about 5 percent maleic anhydride grafted polyethylene, and the thermoplastic is about 45 to about 75 percent polyethylene.  
     
     
         19 . The moldable thermoplastic composite composition as recited in  claim 16 , wherein the coupling agent is up to about 10 percent ethylene methacrylic or acrylic acid, and the thermoplastic is about 40 to about 70 percent of polyethylenes, polypropylenes, polyanimides, polyvinyl chloride, ABS, polystyrene, polyester or mixtures thereof.  
     
     
         20 - 25 . (canceled)