Cellulose-based end-grain core material and composites

Abstract

A composite structural product is provided which comprises light weight cores made from processed kenaf, balsa or other cellulosic stalks bonded together. These may be conveniently manufactured into core blocks, and later sized and joined as the core member of a composite structure, e.g. laminates, fiberglass walls, or plastic encased products. The other members of the composite could include many different materials, from metals to woods to synthetic polymers such as thermoplastic and thermosetting resins. In one form, the kenaf or balsa stalks are formed into small strips or grindings for use as a light core weight filler in molding processes. If combined with yet other strong materials like bamboo in the core, a light-weight, stronger, and cheaper core can be achieved for, e.g., “plastic wood” applications. Thus, an improved core and composite, and process for making them, is provided that has the ability to overcome the disadvantages of the presently available structural materials.

We claim:  
     
         1 . A composite comprising a core of plural cellulosic stalks.  
     
     
         2 . The composite of  claim 1 , wherein the core of plural cellulosic stalks comprises bonded stalks of one of the group of kenaf or balsa.  
     
     
         3 . The composite of  claim 2 , wherein the plural cellulosic stalks comprise shaped stalks.  
     
     
         4 . The composite of  claim 2 , wherein the bonded stalks further comprise compressed stalks having a density of less than 20 pounds per cubic foot.  
     
     
         5 . The composite of  claim 1 , wherein the composite further comprises one of the group of a laminate further comprising a first sheet adhered to the core, a fiberglass structure further comprising a shaped structural member and a fiberglass member on opposing sides of the core, and a plastic structural member comprising plastic surrounding the core.  
     
     
         6 . The composite of  claim 1 , wherein the plastic structural member comprises an interior element comprising a plurality of bamboo tape elements and the core and is formed in the shape of one of the group consisting of beams, columns, poles and dimensional lumber.  
     
     
         7 . The composite of  claim 1 , wherein the plural cellulosic stalks comprise compressed stalks bonded with a binder, the binder comprising at least one member selected from the group consisting of maleated polypropylene, maleated polyethylene, maleic anyhdride, hydroxyl methacrylate, silane compounds, N-vinyl pyridine, Nvinyl caprolactam, N-vinyl carbazole, methacrylic acid, ethyl methacrylate, isobutyl methacrylate, sodium styrene sulfonate, bis-vinyl phosphate, divinyl ether-ethylene glycol, vinyl acetate, vinyl toluene, vinylidene chloride, chloroprene, isoprene, dimethylaminoethyl methacrylate, isocetylvinyl ether, acrylonitrile, glycidyl methacrylate, N-vinyl pyrrolidone, acrylic acid, ethyl acrylate, itaconic acid, methyl acrylate, sodium vinyl sulfonate, cetyl vinyl ether, divinyl ether-butanediol, octadecyl vinyl acetate, and a latex glue.  
     
     
         8 . A product comprising a core block of plural cellulosic stalks.  
     
     
         9 . The product of  claim 8 , wherein the core comprises stalks of one of the group of kenaf or balsa bonded with a binder, the binder comprising at least one member selected from the group consisting of maleated polypropylene, maleated polyethylene, maleic anyhdride, hydroxyl methacrylate, silane compounds, N-vinyl pyridine, Nvinyl caprolactam, N-vinyl carbazole, methacrylic acid, ethyl methacrylate, isobutyl methacrylate, sodium styrene sulfonate, bis-vinyl phosphate, divinyl ether-ethylene glycol, vinyl acetate, vinyl toluene, vinylidene chloride, chloroprene, isoprene, dimethylaminoethyl methacrylate, isocetylvinyl ether, acrylonitrile, glycidyl methacrylate, N-vinyl pyrrolidone, acrylic acid, ethyl acrylate, itaconic acid, methyl acrylate, sodium vinyl sulfonate, cetyl vinyl ether, divinyl ether-butanediol, and octadecyl vinyl acetate, and a latex glue.  
     
     
         10 . A method of forming a composite product comprising: 
 providing a mold defining a shape for the product;    positioning a cellulosic stalk core into the mold so as to allow a desired thickness of plastic to be injected around the core;    injecting heated liquid plastic into the mold to said a desired thickness;    allowing the plastic to cool and to solidify; and    removing the product from the mold.    
     
     
         11 . The method of  claim 10 , wherein the step of positioning the core further comprises positioning along with the core a bamboo element coated with a binding agent comprising one of the group of maleated polypropylene, maleated polyethylene, maleic anyhdride, hydroxyl methacrylate, N-vinyl pyridine, N-vinyl caprolactam, N-vinyl carbaxole, methacrylic acid, ethyl methacrylate, isobutyl methacrylate, sodium styrene sulfonate, bis-vinyl phosphate, divinyl ether-ethylene glycol, vinyl acetate, vinyl toluene, vinylidene chloride, chloroprene, isoprene, dimethylaminoethyl methacrylate, isocetylvinyl ether, acrylonitrile, glycidyl methoacrylate, N-vinyl pyrrolidone, acrylic acid, ethyl acrylate, itaconic acid, methyl acrylate, sodium vinyl sulfonate, cetyl vinyl ether, divinyl ether-butanediol, octadecyl vinyl acetate, latex glue, acrylic acid, maleic anhydride, or salt or ester derivatives thereof.  
     
     
         12 . A method for forming a core for use in composites, comprising: 
 a. coating plural cellulosic stalks with a binder;    b. forcing said stalks together allowing the binder to adhere said stalks into a bound core block.    
     
     
         13 . The method of  claim 12 , further comprising: 
 c. cutting said core block into plural shaped core sheets.    
     
     
         14 . The method of  claim 12 , wherein step b further comprises compressing said stalks to form a denser bundle of stalks while allowing the binder to adhere.  
     
     
         15 . The method of  claim 12 , wherein step a is preceded by shaping said stalks into a desired form for use in forming said bound core block.