Patent Publication Number: US-2019168484-A1

Title: Composite panel and method of forming same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Patent Application No. PCT/CA2017/050888 with a filing date of Jul. 25, 2017, designating the United States, now pending, and further claims priority to U.S. Provisional Application No. 62/367,245 with a filing date of Jul. 27, 2016. The content of the aforementioned applications, including any intervening amendments thereto, are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The application relates generally to panels and, more particularly, to a composite panel and a method of forming same. 
     BACKGROUND OF THE ART 
     Wood composites typically consist of one type of wood adhered to another type of wood to provide a structural and/or aesthetic product. Some conventional wood composites must have a certain minimum thickness to provide them with the requisite structural properties for their given application. This minimum thickness, however, makes them unsuitable for other applications which require a thinner wood composite. Furthermore, some wood composites do not sufficiently resist moisture on their own, and thus require relatively costly coatings, or relatively complicated moisture barriers, to make them suitable for a given application. 
     SUMMARY 
     In one aspect, there is provide a composite panel, comprising: a sheet having layers, at least two of the layers being kraft paper, the layers being stacked on each other and adhered together with a resin, the sheet being corrugated with alternating peaks and valleys disposed sequentially along an axis of the sheet, each peak having a plateau and each valley having a base, each of the plateaus and the bases lying in a plane being substantially parallel to the axis of the one sheet. 
     In another aspect, there is provided a method of forming a structural composite panel, comprising: stacking layers and adhering the layers together to form a sheet, at least two of the layers being kraft paper; and corrugating the sheet along an axis to form alternating peaks and valleys disposed sequentially along the axis, each peak having a plateau and each valley having a base, each of the plateaus and the bases lying in a plane being substantially parallel to the axis of the sheet. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the accompanying figures in which: 
         FIG. 1A  is a perspective view of multiple composite panels stacked together, according to an embodiment of the present disclosure; 
         FIG. 1B  is a schematic side elevational view of part of one of the composite panels of  FIG. 1A ; and 
         FIG. 2  is a cross-sectional schematic view of part of a composite panel, according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  illustrates a composite panel  10 . More particularly,  FIG. 1A  shows multiple nested composite panels  10  stacked one on top of the other. In the depicted embodiment, the composite panel  10  includes a sheet  11  and is provided in sheet form. The entire sheet  11  is made up of the composite materials of the composite panel  10 . The composite panel  10  can be used for structural applications, such as in flooring, walls, or panels, because it can support loads applied on either side of the sheet  11 . In the depicted embodiment, the sheet  11  is corrugated. In an alternate embodiment, the sheet  11  has another undulated or wave-like shape. An outer surface of the composite panel  10  can have a finishing or lining to provide an aesthetically-pleasing appearance. As will be described in greater detail below, the composite panel  11  is a corrugated, thin, self-standing and self-supported structure made from relatively thin layers of materials. 
     Referring to  FIG. 1B , the composite panel  10  is a stack-up of layers. More particularly, the sheet  11  includes multiple layers  20 . Each of the layers  20  is stacked one against the other to form the structure of the sheet  11 , and thus the structure of the composite panel  10 . The superposition of the layers  20  may help the sheet  11  to better resist compressive forces. Two or more of the layers  20  are layers of kraft paper  21 . Kraft paper, sometimes simply referred to as “kraft”, is any suitable paper or paperboard produced from pulp using the Kraft process. In the depicted embodiment, the sheet  11  includes only two layers  20 . More particularly, the sheet  11  in  FIG. 1B  is composed only of two layers of kraft paper  21  which are stacked to abut against one another, and are adhered directly together with a resin  22 . Alternate embodiments and constructions of the sheet  11  are within the scope of the present disclosure, and some of these are described in greater detail below. 
     The layers  20  are adhered together with the resin  22 . The resin  22  can be any suitable compound or adhesive that is capable of such functionality. For example, the resin  22  can be a thermoset resin  22 . Some non-limiting examples of resins  22  that can be used include poly(vinyl acetate) (PVAc), polymeric Methylene Diphenyl Diisocyanate (pMDI), phenol formaldehyde (PF), and Melamine Urea Formaldehyde (MUF). Any number of applications of resin  22 , having any suitable thickness, can be applied to one or both of the surfaces of the layers  20 . When the resin  22  is applied, one or both of the temperature and a humidity level of the resin  22  can be controlled. The pressure at which the resin  22  is applied may also be controlled. Furthermore, the temperature and pressure at which the resin  22  is applied can be optimised depending on a number of factors, such as the type of resin  22  being used, and the thickness of the layers  20 . 
     The corrugated sheet  11  is shaped to have alternating peaks  23  and valleys  24  disposed sequentially along an axis  25  of the sheet  11 . The axis  25  of the sheet  11  is the axis  25  along which the sheet  11  is corrugated. Along the axis  25  of the sheet  11 , each peak  23  is immediately adjacent to a valley  24 , which is immediately adjacent to another peak  23 . It will be appreciated that the designation of peaks  23  and valleys  24  can be inverted, such that the peaks  23  become valleys  24  and vice versa when the sheet  11  is inverted. 
     Each peak  23  has a plateau  23 A and each valley  24  has a base  24 A. The plateau  23 A includes the highest surface of the peak  23 , and the base  24 A includes the lowest surface of the valley  24 . The plateaus  23 A and the bases  24 A are the portions of the sheet  11  spaced furthest from each other in a direction transverse to the axis  25 . The plateaus  23 A and the bases  24 A are planar bodies. In the depicted embodiment, they are substantially flat members which lie in a plane that is substantially parallel to the axis  25 . The corrugated sheet  11  also has intermediate segments  26  which extend between and interconnect the adjacent peaks  23  and valleys  24 . One end of each intermediate segment  26  has a first joint portion  26 A connecting the intermediate segment  26  to the plateau  23 A. The other, opposite end of each intermediate segment  26  has a second joint portion  26 B connecting the intermediate segment  26  to the base  24 A. The flat plateaus  23 A and flat bases  24 A, in conjunction with the intermediate segments  26 , provide the corrugated sheet  11  with a trapezoidal shape. The trapezoidal corrugation of the sheet  11  may help to better resist compressive forces. The trapezoidal corrugation of the sheet  11  allows facilitates the stacking or nesting of one sheet  11  over the other, as shown in  FIG. 1A . 
     Possible dimensions for the corrugation of the composite panel  10  are now discussed in reference to  FIG. 1B . Each plateau  23 A and each base  24 A has a length L defined along the axis  25  of the sheet  11  of about 11 mm or 0.43 in, with a variation on either side of 0.1 mm or 0.0039 in. The sheet  11  has a thickness T measured transverse to the axis  25  of the sheet  11 . The thickness T in  FIG. 1B  is measured from an outer surface of one of the plateaus  23 A to the outer surface of an adjacent base  24 A. The thickness is about 19 mm or 0.75 in., with a variation on either side of 1 mm or 0.039 in. The thickness T of the panel  10  is therefore relatively small (i.e. less than 1 in.), and the panel  10  is therefore relatively thin. Adjacent plateaus  23 A, and thus adjacent bases  24 A, are separated by a distance S measured along the axis  25 . The distance S is about 50 mm, with a variation on either side of 3 mm or 0.12 in. 
     Still referring to  FIG. 1B , an axial distance C between the plateaus  23 A and the bases  24 A is defined. The distance C is a measure of the distance along the axis  25  separating the end of the bases  24 A and the beginning of a neighbouring or adjacent plateau  23 A. The distance C is similarly a measure of the distance separating the end of the plateaus  23 A and the beginning of a neighbouring or adjacent base  24 A. In  FIG. 1B , the distance C is about 14 mm or 0.55 in, with a variation on either side of 0.5 mm or 0.020. 
     The first joint portion  26 A of the intermediate segments  26  is curved and has a first radius of curvature R 1 . The second joint portion  26 B is also curved and has a second radius of curvature R 2 . The intermediate segments  26  are therefore joined to the plateaus  23 A and the bases  24 A along curved portions  26 A, 26 B. In the depicted embodiment, the first radius of curvature R 1  is different than the second radius of curvature R 2 . More particularly, the first radius of curvature R 1  is about 5.7°, with a variation on either side of 0.1°. The second radius of curvature R 2  is about 3.1°, with a variation on either side of 0.1°. An angle of corrugation a is defined between a plane P being perpendicular to the axis  25  and each intermediate segment  26 . The angle of corrugation a in  FIG. 1B  is constant such that the corrugation of the sheet  11  is the same along the axis  25 . In an alternate embodiment, the angle of corrugation a varies between the peaks  23  and valleys  24 , such that the corrugation of the sheet  11  changes along the axis  25 . In the depicted embodiment, the angle of corrugation is about 26°, with a variation on either side of 1°. 
     Part of another embodiment of the panel  110  is shown in  FIG. 2 .  FIG. 2  shows a cross-section of part of the sheet  111  of the panel  110 . The layers  20  of the sheet  111  include a layer of wood veneer  40 . The wood veneer  40  may be made by “peeling” a circular wood log or by slicing large blocks of wood. Other techniques are possible. The type of wood used for the wood veneer  40  can vary. For example, where the wood veneer  40  will be visible and serve an aesthetic function, the wood used to make the wood veneer  40  can be a hardwood or a wood having a nice growth ring pattern. Similarly, where the wood veneer  40  will be hidden and serve a primarily structural function, a relatively inexpensive softwood can be used. It is observed that wood species with higher densities provide greater stiffness to the composite panel  110 . The layers of wood veneer  40  are relatively thin, for example thinner than about 3 mm or 0.125 in. 
     The wood veneer  40  has wood fibers  42  or grains which have an orientation. The orientation of the wood fibers  42  may depend on the manner by which the layer of wood veneer  40  is made. For example, where the layer of wood veneer  40  is peeled from an elongated log, the wood fibers  42  will have an orientation being substantially parallel to the longitudinal axis of the log. It is observed that the wood veneer  40  provides a relatively stiff resistance to bending in the direction of the orientation of its wood fibers  42 , while being relatively pliable in a direction that is transverse to the orientation of its wood fibers  42 . It can thus be appreciated that the orientation of the wood fibers  42  can be selected to optimise bending and/or pliability along any desired direction. The wood veneer  40  can be provided so that the majority of its wood fibers  42  are substantially parallel to one another, and oriented in the same direction. For example, at least 70% of the wood fibers  42  of the wood veneer  40  can be oriented along one direction. This single direction can be parallel to the axis  25  of the sheet  111 , or transverse thereto. In alternate embodiments, the layers  20  include more than one layer of wood veneer  40 . 
     Each layer of wood veneer  40  has a first side  44  and a second side  46 . The first and second sides  44 , 46  define exposed outer surfaces of the wood veneer  40  against which the resin  22  may be applied. While the first and second sides  44 , 46  define substantially continuous surfaces, the wood fibers  42  of the wood veneer  40  are not perfectly or uniformly distributed at the surfaces such that pores  48  may be formed at the surfaces. Stated differently, the pores  48  extend into the body of the wood veneer  40  from the surfaces defined by its first and second sides  44 , 46 . The pores  48  collectively form a wood matrix  49  that extends at least partially into the body of the wood veneer  40  from each of its first and second sides  44 , 46 . The resin  22  penetrates into the wood matrix  49  to seal the pores  48 . 
     The resin  22  is applied to one, or both, of the first and second sides  44 , 46  of the wood veneer  40 . The application of the resin  22  over the surfaces defined by the first and second sides  44 , 46  fills the pores  48  with the resin  22 , which penetrates into the wood matrix  49 . The resin  22  blocks the pores  48  and therefore seals them to prevent the ingress of moisture into the wood veneer  40 . 
     Still referring to  FIG. 2 , the application of the resin  22  to one or both of the first and second sides  44 , 46  will depend at least in part on the desired configuration of the composite panel  10 . For example, in the configuration where the composite panel  10  is made up of one layer of wood veneer  40  which is covered on one side with a layer of kraft paper  21  and exposed on the other, the resin  22  is applied to only one of the first and second sides  44 , 46 . In the depicted embodiment of  FIG. 2  where the composite panel  10  is made up of one layer of wood veneer  40  which is covered on both sides with kraft paper  21 , the resin  22  is applied to both the first and second sides  44 , 46 , and the kraft paper  21  is applied over the resin-filled pores  48  of each of the first and second sides  44 , 46 . The layers of kraft paper  21  in this configuration are indirectly adhered together via the core layer of wood veneer  40 . 
     In the configuration where the composite panel  10  is made up of two abutting wood veneers  40  covered on their exposed surfaces by liners, the resin  22  is applied to both the first and second sides  44 , 46  of the first wood veneer  40 , the kraft paper  21  is applied over the resin-filled pores  48  of one of the first and second sides  44 , 46  of the first wood veneer  40 , the second wood veneer  40  is applied over the resin-filled pores  48  of the other side  44 , 46  of the first wood veneer  40 , the resin  22  is applied to the free side of the second wood veneer  40 , and another layer of kraft paper  21  is applied over the resin  22  of the free side of the second wood veneer  40  to adhere the second kraft paper  21  to the free side of the second wood veneer  40 . It is therefore possible to form many configurations of the composite panel  10  including, but not limited to, liner-resin-liner (i.e. kraft paper-resin-kraft paper), liner-resin-veneer-resin-liner, and liner-resin-veneer-resin-veneer-liner. In an alternate embodiment, the liner is a polymer film or sheet. 
     It can thus be appreciated that the resin  22  and its parameters of application can be optimised to encourage “polymerisation” with the wood veneer  40 , a process similar to the chemical reaction by which monomer molecules react together to form polymer chains. Stated differently, the resin  22  becomes embedded at depth in the wood matrix  49  of the wood veneer  40  such that, when the resin  22  is cured, the resin  22  and wood veneer  40  are integral with one another. The resin  22  therefore both seals the pores  48  of the wood matrix  49 , and serves as an adhesive to strongly bind the kraft paper  21  to the wood veneer  40 . 
     In the depicted embodiment, in which the liner is a layer of kraft paper  21 , the kraft paper  21  contributes to the strength of the composite panel  110 . The kraft paper  21  has paper fibers  62 , the majority of which are oriented along the same direction. In the depicted embodiment, the paper fibers  62  are oriented substantially transverse to the orientation of the wood fibers  42  (which are shown being oriented into the page). It can thus be appreciated that the kraft paper  21 , once adhered to the wood veneer  40  via the resin  22 , helps to reinforce the strength of the composite panel  110 , particularly in the direction along which the paper fibers  62  are oriented. In such a configuration, the kraft paper  21  reinforces the composite wood material  30  in a direction that is transverse to the orientation of the wood fibers  42 . This is desirable because the composite panel  10  is expected to have the least amount of mechanical resistance in the direction transverse to the wood fibers  42 . The kraft paper  21  therefore allows the wood fibers  42  to be linked across the grain direction of the wood veneer  40 . In embodiments where the kraft paper  21  has a relatively high tensile strength, it contributes to the overall strength of the composite panel  110 . 
     The orientation of the paper fibers  62  of the layers of kraft paper  21  may also contribute to the overall strength of the composite panel  10  in  FIGS. 1A and 1B . In the depicted embodiment where the composite panel  10  includes only two layers of kraft paper  21 , a majority of the paper fibers  62  are aligned in a direction transverse to the axis  25  of the sheet  11 . In the depicted embodiment, the paper fibers  62  are shown being oriented into the page, and only a representative sample of all the paper fibers  62  is shown. (Inventeurs: merci de nous indiquer le pourcentage des fibres qui sont orientés perpendiculaires à la corrugation) 
     Examples of layers of kraft paper  21 , and their thickness and weight, are now discussed. One possible material for the layers of kraft paper  21  includes Chipboard 20 pts. The thickness of a single layer of Chipboard 20 pts. is 0.51 mm or 0.02 in. An embodiment of the composite panel  10  having only two layers of Chipboard 20 pts. adhered together with the resin  22  provided a thickness of 0.97 mm or 0.04 in, and a weight of 99.1 g/ft 2 . Another possible material for the layers of kraft paper  21  includes Chipboard 30 pts. The thickness of a single layer of Chipboard 30 pts. is 0.75 mm or 0.03 in. An embodiment of the composite panel  10  having only two layers of Chipboard 30 pts. adhered together with the resin  22  provided a thickness of 1.59 mm or 0.06 in, and a weight of 137.1 g/ft 2 . An embodiment of the composite panel  110  having two layers of paper liner  21  adhered to a core layer of wood veneer  40 , as shown in  FIG. 2 , provided a thickness of 1.18 mm or 0.045 in. 
     Testing was performed on embodiments of the composite panel  10 , 110  of the present disclosure, and the results are now described in greater detail. Table 1 below presents the results of testing to determine the modulus of elasticity (MOE), the edgewise compression strength (ECT), and the flat crush test (FCT) for a composite panel  10  having only two layers of kraft paper  21 , of either Chipboard 20 pts. or the thicker Chipboard 20 pts., adhered together with the resin  22 . 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Composite Panel Having only Two Paper Layers 
               
            
           
           
               
               
               
            
               
                   
                 Chipboard 20 
                 Chipboard 30 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 MOE (ASTM D 1037 
                 145 
                 200 
               
               
                   
                 adapted) (MPa) 
               
               
                   
                 Edgewise Compressive 
                 17.5 
                 23.5 
               
               
                   
                 Strength (ECT) (N/mm) 
               
               
                   
                 Flat Crush Test 
                 41 
                 96 
               
               
                   
                 (FCT) (KPa) 
               
               
                   
                   
               
            
           
         
       
     
     Table 1 reveals that by increasing the thickness of each layer of kraft paper  21  by about 0.25 mm or 0.01 in., a relatively small amount, improvements in MOE, ECT, and FCT are obtained. 
     Table 2 below presents the results of testing to determine the MOE, the ECT, and the FCT for a composite panel  110  having two layers of kraft paper  21  adhered to a central core layer of wood veneer  40 . In the middle column, the kraft paper  21  is 28 lb medium and the wood veneer is 0.8 mm thick BassWood. In the right column, the kraft paper  21  is Chipboard 30 pts. and the wood veneer is 0.8 mm thick BassWood. Thus the only difference between the two constructions of the composite panel  110  is the layer of kraft paper  21 . 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Composite Panel Having Two Paper 
               
               
                 Layers and Wood Veneer Core 
               
            
           
           
               
               
               
            
               
                   
                 28 lb medium, 
                 Chipboard 30, 
               
               
                   
                 0.8 mm thick 
                 0.8 mm thick 
               
               
                   
                 BassWood 
                 BassWood 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 MOE modulus of 
                 730 
                 1030 
               
               
                   
                 elasticity (ASTM D 
               
               
                   
                 1037 adapted) (MPa) 
               
               
                   
                 Edgewise Compressive 
                 74 
                 96 
               
               
                   
                 Strength (ECT) (N/mm) 
               
               
                   
                 Flat Crush Test 
                 60 
                 158 
               
               
                   
                 (FCT) (KPa) 
               
               
                   
                   
               
            
           
         
       
     
     Table 2 reveals that by increasing the thickness of each layer of kraft paper  21  by a relatively small amount, improvements in MOE, ECT, and FCT are obtained. Indeed, the FCT, which is a measure of the resistance of the composite panel  110  to compression, and thus a measure of the structural strength of the composite panel  110 , more than doubles. 
     Table 3 below presents the results of testing to determine the MOE, the ECT, and the FCT for another composite panel  110  having two layers of 28 lb medium kraft paper  21  adhered to a central core layer of wood veneer  40 . In the middle column, the wood veneer is 0.6 mm thick BassWood. In the right column, the wood veneer is 0.7 mm thick Birch Wood. Thus the only difference between the two constructions of the composite panel  110  is the core layer of wood veneer  40 . 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Composite Panel Having Two Paper 
               
               
                 Layers and Wood Veneer Core 
               
            
           
           
               
               
               
            
               
                   
                 28 lb medium, 
                 28 lb medium, 
               
               
                   
                 0.6 mm thick 
                 0.7 mm thick 
               
               
                   
                 BassWood 
                 Birch Wood 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 MOE (ASTM D 1037 
                 960 
                 1370 
               
               
                   
                 adapted) (MPa) 
               
               
                   
                 Edgewise Compressive 
                 126 
                 173 
               
               
                   
                 Strength (ECT) (N/mm) 
               
               
                   
                 Flat Crush Test 
                 131 
                 170 
               
               
                   
                 (FCT) (KPa) 
               
               
                   
                   
               
            
           
         
       
     
     Table 3 reveals that by increasing the thickness of the core layer of wood veneer  40  by a relatively small amount (i.e. 0.1 mm or 0.004 in.), improvements in MOE, ECT, and FCT are obtained. 
     Table 4 below illustrates the effect of adding a core layer of wood veneer  40  between two layers of kraft paper  21 . Table 4 below presents the results of testing to determine the MOE, the ECT, and the FCT for i) a composite panel  10  having only two layers of kraft paper  21  of Chipboard 30 pts. (middle column), and ii) a composite panel  110  having two layers of kraft paper  21  of Chipboard 30 pts. adhered to a central core layer of wood veneer  40  of 0.8 mm thick BassWood (right column). Thus the only difference between the two constructions of the composite panel  10 , 110  is the core layer of wood veneer  40 . 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Two Composite Panel Constructions 
               
            
           
           
               
               
               
            
               
                   
                   
                 CHIP 30, 0.8 mm 
               
               
                   
                 CHIP 30 
                 thick BassWood 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 MOE (ASTM D 1037 
                 200 
                 1030 
               
               
                   
                 adapted) (MPa) 
               
               
                   
                 Edgewise Compressive 
                 23.5 
                 96 
               
               
                   
                 Strength (ECT) (N/mm) 
               
               
                   
                 Flat Crush Test 
                 96 
                 158 
               
               
                   
                 (FCT) (KPa) 
               
               
                   
                   
               
            
           
         
       
     
     Table 4 reveals that by providing a core layer of wood veneer  40  between two layers of kraft paper  21 , and thus increasing the thickness of the composite panel  10 , 110  by a relatively small amount, improvements in MOE, ECT, and FCT are obtained. Indeed, the FCT, which is a measure of the resistance of the composite panel  10 , 110  to compression, and thus a measure of the structural strength of the composite panel  110 , almost doubles. The MOE increases about fivefold, and the ECT increases more than fourfold. 
     Table 5 below illustrates the effect of adding different layers of kraft paper  21  to the same core layer of wood veneer  40 . Table 5 below presents the results of testing to determine the MOE, the ECT, and the FCT for i) a composite panel  110  having only two layers of kraft paper  21  of 28 lb medium (middle column) adhered to a central core layer of wood veneer  40  of 0.8 mm thick BassWood, and ii) a composite panel  110  having two layers of kraft paper  21  of Chipboard 30 pts. adhered to a central core layer of wood veneer  40  of 0.8 mm thick BassWood (right column). Thus the only difference between the two constructions of the composite panel  110  is the type of kraft paper  21 . 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Two Composite Panel Constructions 
               
            
           
           
               
               
               
            
               
                   
                 28 lb medium, 
                 CHIP 30, 
               
               
                   
                 0.8 mm thick 
                 0.8 mm thick 
               
               
                   
                 BassWood 
                 BassWood 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 MOE (ASTM D 1037 
                 730 
                 1030 
               
               
                   
                 adapted) (MPa) 
               
               
                   
                 Edgewise Compressive 
                 74 
                 96 
               
               
                   
                 Strength (ECT) (N/mm) 
               
               
                   
                 Flat Crush Test 
                 60 
                 158 
               
               
                   
                 (FCT) (KPa) 
               
               
                   
                   
               
            
           
         
       
     
     Table 5 reveals that by increasing the thickness of each layer of kraft paper  21  adhered to the same core layer of wood veneer  40  by a relatively small amount, improvements in MOE, ECT, and FCT are obtained. Indeed, the FCT, which is a measure of the resistance of the composite panel  110  to compression, and thus a measure of the structural strength of the composite panel  110 , more than doubles. 
     Table 6 below illustrates the effect of changing the core layer of wood veneer  40  between two identical layers of kraft paper  21 . Table 6 below presents the results of testing to determine the MOE, the ECT, and the FCT for i) a composite panel  110  having two layers of kraft paper  21  of 28 lb medium (middle column) adhered to a central core layer of wood veneer  40  of 0.6 mm thick BassWood, and ii) a composite panel  110  having two layers of kraft paper  21  of 28 lb medium adhered to a central core layer of wood veneer  40  of 0.7 mm thick Birch Wood (right column). Thus the only difference between the two constructions of the composite panel  110  is the type of wood species used for the core layer of wood veneer  40 . 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Two Composite Panel Constructions 
               
            
           
           
               
               
               
            
               
                   
                 28 lb medium, 
                 28 lb medium, 
               
               
                   
                 0.6 mm thick 
                 0.7 mm thick 
               
               
                   
                 BassWood 
                 Birch Wood 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 MOE (ASTM D 1037 
                 960 
                 1370 
               
               
                   
                 adapted) (MPa) 
               
               
                   
                 Edgewise Compressive 
                 126 
                 173 
               
               
                   
                 Strength (ECT) (N/mm) 
               
               
                   
                 Flat Crush Test 
                 131 
                 170 
               
               
                   
                 (FCT) (KPa) 
               
               
                   
                   
               
            
           
         
       
     
     Table 6 reveals that by changing the species of wood for the core layer of wood veneer  40  and by increasing the thickness of the core layer of wood veneer  40  by a relatively small amount, improvements in MOE, ECT, and FCT are obtained. 
     Referring to  FIGS. 1A and 1B , there is disclosed a method of forming the structural composite panel  10 , 110 . The method includes stacking the layers  20  and adhering the layers  20  together to form the sheet  11 , where at least two of the layers  20  are layers of kraft paper  21 . The method includes corrugating the sheet  11  along the axis  25  to form alternating peaks  23  and valleys  24  disposed sequentially along the axis  25 . Each peak  23  has a plateau  23 A and each valley  24  has a base  24 A. Each of the plateaus  23 A and the bases  24 A lie in a plane being substantially parallel to the axis  25  of the sheet  11 . 
     Referring to  FIG. 2 , the method also includes applying the kraft paper  21  over the resin-filled pores  48  of the wood matrix  49  to adhere the kraft paper  21  to a corresponding side  44 , 46  of the wood veneer  40 . The kraft paper  21  can be any suitable material that seals the resin  22  between the kraft paper  21  and the corresponding side  44 , 46 . In most embodiments, but not necessarily all, the kraft paper  21  will be in the form of a sheet of the material. The material of the kraft paper  21  can include, but is not limited to, paperboard, kraft paper. The kraft paper  21  can also be coloured or be printed upon to provide a desired surface finish to the composite panel  10 , 110 . 
     The method also includes curing the resin  22  to form the composite panel  10 , 110 . The step of curing can take many forms and will be largely dependent on the resin  22  being used. For example, some resins  22  can be air-cured, while others are cured through the application of heat. Pressure can also be applied to the liner-resin-wood veneer construction during the curing process. Once cured, the resin  22  is irreversibly linked with the wood veneer  40  and/or its wood fibers  42 , as well as with the kraft paper  21 . 
     It can thus be appreciated that the present disclosure relates to a composite panel  10 , in one embodiment, having its primary structural properties provided by layers of kraft paper  21 . The composite panel  10  is therefore a corrugated paper product that provides structural strength with relatively thin layers of paper. 
     It can be further appreciated that the present disclosure relates to a composite panel  110 , which in one embodiment, having its primary structural properties provided by a wood veneer  40  core in combination with kraft paper  21 . The penetration of the resin  22  into the wood matrix  49  allows for the formation of an integrated, rigid, and reinforced composite panel  110 . 
     The possibility of controlling the orientation of the wood fibers  42 , and thus controlling the direction of flexion of the composite panel  110 , allows the composite panel  110  to be provided as a flat object, or a rolled sheet. 
     Indeed, the ability to provide both the wood veneer  40  and the kraft paper  21  in sheet form allows the composite panel  10 , 110  to be formed from a continuous fabrication process in which a sheet of the wood veneer  40  is displaced with rollers, the resin  22  is applied, and a sheet of the kraft paper  21  is placed onto the resin  22  using rollers and pressed thereagainst. Such a fabrication process is rapid and cost-effective. 
     The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.