Abstract:
A method of manufacturing a contoured sports board comprising the steps of providing a non-expanded film layer ( 16 ), providing a polymer foam layer ( 18, 19 ), bonding the film layer to the foam layer to form a top laminated sheet ( 16/17/18/19 ), providing a bottom sheet ( 21/22/23, 30 ), providing a mold having a top portion ( 44 ) and a bottom portion ( 45 ), the top and bottom portions having inner surfaces ( 63, 64 ) and configured to be placed in opposition to each other with their inner surfaces defining a cavity ( 49 ) therebetween, the inner surface of the top portion of the mold having contouring defining at least one valley ( 61, 62 ), placing the film layer of the top sheet against the inner surface of the top mold portion, mixing an isocyanate and a polyol component to provide a urethane foam forming mixture ( 50 ), spraying the mixture on the foam layer of the top sheet, placing the bottom sheet on the top sheet with the mixture between the top sheet and the bottom sheet, placing the inner surface of the bottom portion of the mold on the bottom sheet, mating the bottom portion of the mold with the top portion of the mold, applying pressure to the mold, allowing the mixture time to expand between the top sheet and the bottom sheet, unmating the top and bottom portions of the mold, whereby heat from the expansion of the mixture to form a polyurethane foam core heat laminates the top sheet and the bottom sheet to the polyurethane core to form a board having an outer surface contour generally conforming to the contour of the inner surfaces of the mold.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to foam sports boards for recreational use and, more particularly, to a contour-molded laminated foam sports board having a polyurethane foam core.  
       BACKGROUND ART  
       [0002]     Body boards for riding waves, ski boards and gliding boards made for use on snow, and other recreational sports boards made of foam, are known in the prior art. Such boards typically include a core with laminated layers surrounding the core. The outer base layer of the laminate is adapted to used on a particular sports surface (water or snow) and the top laminated layer often includes some type of imprinted graphics.  
         [0003]     For example, it is known that ski or snow boards may be constructed with a polyethylene base layer having longitudinally extending steel edges laminated to a thermoset composite such as uncured preimpregnated fiberglass. This base laminate is then applied to a preformed polyurethane foam core. Upper layers, generally consisting of a plastic top sheet, a non-woven fabric intermediate layer, and a fiberglass reinforcement layer, are applied to the top surface of the core. The conventional manufacturing process for this type of board is by compression molding. The process calls for hand laying each layer and applying resin, typically epoxy or polyester based, to impregnate the different layers. Heat and pressure are then applied, with the bonding between layers provided by the resin after it has cured for a period of time at a raised temperature. However, this type of board and manufacturing process has a number of drawbacks. For example, the preformed polyurethane foam core, the polyethylene layer and the thermoset fiberglass composite layer are generally required to be subjected to a special sanding process in order to roughen the bonding surfaces and get the bond strength required. In addition, the thermoset fiberglass composite layers are difficult to work with and require substantial curing periods during the production process.  
         [0004]     Another type of sports board known in the prior art is a wakeboard. These boards generally have a preformed and preshaped polyurethane foam core with layers of reinforcement, such as fiberglass, carbon fiber or the like, applied to the bottom and top surfaces of the foam core. A plastic sheet having an intermediate layer of non-woven fabric forms the base of the board. The top of these boards are formed of one or more layers of reinforcement, typically fiberglass, with a graphic imprinted fabric top sheet laid above the fiberglass reinforcement layer. These boards are also manufactured using the above described compression molding and have the same drawbacks as described with the prior art snow boards.  
         [0005]     A second manufacturing process known in the prior art is to use thermosetting resins, such as a polyurethane foam resin, to laminate the boards. For example, with the snow board, a thermoset fiberglass composite layer is laid onto a polyethylene base sheet. However, here too the bonding surfaces have to roughened and a special primer is applied to obtain the required bonding strength when bonding the two layers together. This two layer laminate is then placed on the bottom of a mold. A top laminate of a graphically imprinted plastic sheet, a non-woven fabric intermediate layer, and a thermoset fiberglass composite is then formed. Again, however, the surface of the thermoset composite must be sanded to provide a rough surface for bonding and a special primer is normally used to bond the thermoset composite layer to the non-woven fabric surface of the plastic top sheet. This three layer laminate is then placed on the top of the mold. After the top and bottom mold portions are mated, a polyurethane foam resin is then injected between the base laminate and the top laminate to join the two together by bonding to the roughened thermoset fiberglass composite surfaces.  
         [0006]     As mentioned above, these conventional processes generally require the surfaces of the fiberglass that comes into contact with the foam core to be roughened so that the mechanical bond between these parts is strong enough to avoid premature delamination. In addition, the steps of laying up each layer and applying by hand the thermoset resin for the complete wetting of each layer, as well as waiting for it to cure, and preparing the surfaces to bond well with the foam are labor intensive, time consuming and require experienced technical workers. Thus the cost of manufacturing such boards is high.  
         [0007]     In addition, conventional boards of this type generally include a graphic image which is normally printed on either a rigid plastic top sheet or a fabric sheet. These conventional rigid plastic sheets may include PBT, PA, ABS or TPE and have a typical thickness of 0.5 mm. However, due to the high rigidity of the plastic sheet, they can only be molded into relatively flat surface profiles and cannot be used to provide a more highly contoured surface. The alternative fabric sheets may include natural or synthetic fabrics such as cotton or non-woven fabric and they commonly have a thickness of about 0.3 mm. With fabric sheets, while they can be molded into more contoured shapes, they have other limitations such as inferior image resolution and susceptibility to wrinkle defects in areas of high contouring.  
         [0008]     Foam sleds that include a graphic-imprinted polyethylene film top layer and a polyethylene foam core, together with a polyethylene bottom slick skin are also well-known in the prior art. These can be manufactured using conventional heat lamination to processes because each of the layers has the same polyethylene structure. However, such polyethylene-core foam boards lack the desired rigidity and stiffness that other polymeric foam core boards may have. This lack of rigidity in a polyethylene foam core will cause the sled to flex with the weight of the rider, which can result in the foam sled submerging below the snow surface and thereby reduce the speed and directional stability of the board on a snow covered slope.  
         [0009]     Accordingly, it would be desirable to provide a foam slide having a rigid foam core for faster sliding speed and better tracking stability, while also provide a board that has a top laminate that provides adequate mechanical strength, is soft, is flexible enough to be molded into highly contoured shapes, and can be provided with a wear resistant graphic top surface. It would also be advantageous to be able to manufacture such a board in a cost effective manufacturing process.  
       DISCLOSURE OF THE INVENTION  
       [0010]     With parenthetical reference to the corresponding parts, portions or surfaces of the disclosed embodiment, merely for the purposes of illustration and not by way of limitation, the present invention provides a method of manufacturing a contoured sports board comprising the steps of providing a non-expanded film layer ( 16 ), providing a polymer foam layer ( 18 / 19 ), bonding the film layer to the foam layer to form a top laminated sheet ( 16 / 17 / 18 / 19 ), providing a bottom sheet ( 21 / 22 / 23 ,  30 ), providing a mold having a top portion ( 44 ) and a bottom portion ( 45 ), the top and bottom portions having inner surfaces ( 63 ,  64 ) and configured to be placed in opposition to each other with their inner surfaces defining a cavity ( 49 ) therebetween, the inner surface of the top portion of the mold having contouring defining at least one valley ( 61 ,  62 ), placing the film layer of the top sheet against the inner surface of the top mold portion, mixing an isocyanate and a polyol component to provide a urethane foam forming mixture ( 50 ), spraying the mixture on the foam layer of the top sheet, placing the bottom sheet on the top sheet with the mixture between the top sheet and the bottom sheet, placing the inner surface of the bottom portion of the mold on the bottom sheet, mating the bottom portion of the mold with the top portion of the mold, applying pressure to the mold, allowing the mixture time to expand between the top sheet and the bottom sheet, unmating the top and bottom portions of the mold, whereby heat from the expansion of the mixture to form a polyurethane foam core heat laminates the top sheet and the bottom sheet to the polyurethane core to form a board having an outer surface contour generally conforming to the contour of the inner surfaces of the mold.  
         [0011]     The bottom sheet may be formed by extruding a polymer film layer ( 23 ) and heat laminating the polymer film to a polymer foam layer ( 21 / 22 ) to form a film/foam laminated sheet ( 21 / 22 / 23 ). The polymer film may have a thickness in the range of about 0.3 to about 1.5 mm. The bottom sheet may comprises a thermoplastic polyurethane film layer ( 30 ) and the thermoplastic polyurethane film may have a thickness in the range of about 0.3 to about 1.5 mm. The bottom sheet may have a bottom surface with longitudinally-extending alternating grooves and ridges. The method may further comprise the steps of providing a second non-opaque polymer film layer having an outer surface and an inner surface, applying a graphic image to the inner surface of the second film layer, and laminating the inner surface of the second film layer to the film layer. The film layer may be selected from a group consisting of polyethylene, polypropylene, and a copolymer of ethylene vinyl acetate and polyethylene. The polymer foam layer may be selected from a group consisting of polyethylene foam, polypropylene foam, a copolymer foam of polyethylene and ethylene vinyl acetate, a copolymer foam of polyethylene and polypropylene, and a copolymer foam of polystyrene and polyethylene. The polymer foam layer may be thermoplastic polymer foam.  
         [0012]     The present invention also provides a molded sports board comprising a polyurethane foam core ( 20 ), a graphically imprinted film layer ( 16 ) having an outer surface, an intermediate polymer foam layer ( 18 / 19 ) between the film layer and the core, the film and intermediate layers having a molded profile such that the outer surface of the film layer has a contoured cross-section having multiple ridges ( 55 ,  56 ) and valleys ( 57 ,  58 ) therebetween. The valleys may have a depth ( 65 ) of at least 2 mm.  
         [0013]     Accordingly, the general object of the present invention is to provide an improved manufacturing process for a polyurethane foam core sports board.  
         [0014]     Another object is to provide a sports board that can be molded with deep or severe contouring on the top surface.  
         [0015]     Another object is to provide a sports board having a soft top surface.  
         [0016]     Another object is to provide a sports board having a semi-rigid to rigid polyurethane foam core.  
         [0017]     Another object is to provide a sports board having a sharp and wear-resistant graphic surface.  
         [0018]     Another object is to provide a sports board which can have a graphic-imprinted film surface on both the top and bottom outer surfaces of the board.  
         [0019]     Another object is to provide a board that can be manufactured in a short production cycle time.  
         [0020]     These and other objects and advantages will become apparent from the foregoing and ongoing written specification and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is a top plan view of a first embodiment of the improved sports board.  
         [0022]      FIG. 2  is a top plan view of the sports board shown in  FIG. 1  with certain graphic elements accentuated.  
         [0023]      FIG. 3  is a transverse vertical sectional view of the sports board shown in  FIG. 1 , taken generally on line A-A of  FIG. 1 .  
         [0024]      FIG. 4  is a longitudinal vertical sectional view of the sports board shown in  FIG. 1 , taken generally on line B-B of  FIG. 1 .  
         [0025]      FIG. 5  is a transverse vertical sectional view of a second cross-sectional embodiment of the sports board shown in  FIG. 1 , taken generally on line A-A of  FIG. 1 .  
         [0026]      FIG. 6  is a longitudinal vertical sectional view of the embodiment of the sports board shown in  FIG. 5 , taken generally on line B-B of  FIG. 1 .  
         [0027]      FIG. 7  is a transverse vertical sectional view of a third cross-sectional embodiment of the sports board shown in  FIG. 1 , taken generally on line A-A of  FIG. 1 .  
         [0028]      FIG. 8  is a longitudinal vertical sectional view of the embodiment of the sports board shown in  FIG. 7 , taken generally on line B-B of  FIG. 1 .  
         [0029]      FIG. 9  is a plan view of the top portion of the mold used to form the sports board shown in  FIG. 1 .  
         [0030]      FIG. 10  is a transverse vertical sectional view of the top portion of the mold shown in  FIG. 9 , taken generally on line C-C of  FIG. 9 .  
         [0031]      FIG. 11  is a longitudinal vertical cross-sectional view of the top portion of the mold shown in  FIG. 9 , taken generally on line D-D of  FIG. 9 .  
         [0032]      FIG. 12  is a plan view of the bottom portion of the mold used to form the sports board shown in  FIG. 1 .  
         [0033]      FIG. 13  is a transverse vertical sectional view of the bottom portion of the mold shown in  FIG. 12 , taken generally on line E-E of  FIG. 12 .  
         [0034]      FIG. 14  is a longitudinal vertical sectional view of the bottom portion of the mold shown in  FIG. 12 , taken generally on line F-F of  FIG. 12 .  
         [0035]      FIG. 15  is a schematic showing the process by which the top laminated sheets of the preferred embodiments are formed.  
         [0036]      FIG. 16  is a schematic showing the process by which the bottom laminated sheets of the preferred embodiments are formed.  
         [0037]      FIG. 17   a - e  show the process by which the top and bottom sheets are laminated to the core to form the contoured board shown in  FIG. 1 .  
         [0038]      FIG. 18  is an enlarged longitudinal vertical sectional view of the contouring shown in  FIGS. 1, 4 ,  6  and  8 , taken within the indicated circle of  FIGS. 1, 4 ,  6  and  8 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]     At the outset, it should be clearly understood that like reference numerals are intended to identify the same structural elements, portions or surfaces consistently throughout the several drawing figures, as such elements, portions or surfaces may be further described or explained by the entire written specification, of which this detailed description is an integral part. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this invention. As used in the following description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.  
         [0040]     Referring now to the drawings and, more particularly, to  FIG. 1  thereof, the invention provides an improved contoured sports board, of which the presently preferred embodiment is generally indicated at  15 . As shown in  FIG. 1 , the top surface of the board is deeply contoured with both generally longitudinally and transversely extending ridges  55 ,  56  and valleys  57 ,  58  therebetween. These contours are also shown in the longitudinal vertical cross-sectional views of the preferred embodiments of  FIGS. 4, 6  and  8 , respectively.  FIG. 2  highlights certain of the graphics visible on the top surface of the board. These graphics are distinct and clear even with the highly contoured surfacing of the board.  
         [0041]     As shown in  FIGS. 3-4 , the first embodiment of the molded sports board comprises eight layers laminated together. Top layer  16  is unexpanded polyethylene film with imprinted graphics  40 . The graphics on layer  16  are imprinted using any of several conventional processes for printing on polyethylene. An example of such a process is corona printing, in which an electrical discharge temporarily alters the surface molecules of the polyethylene film, allowing inks to adhere to the film. Layer  16  has a thickness of between about 0.02 and 0.15 mm, and preferably a thickness of about 0.07 mm. Layer  16  has a density in the range of about 0.91 to about 0.96 g/cm 3 , and preferably a density of 0.95 g/cm 3 . Alternatively, layer  16  may comprise two non-expanded polymer film layers in order to provide and protect the graphic image. Rather than having the graphic image imprinted on the inner surface of a single film layer, two film layers may be used. A first non-opaque polymer film imprinted with graphics on one side is bonded to a second polymer film layer by a conventional laminating process, with the graphically imprinted side of the non-opaque film facing the second polymer film layer.  
         [0042]     Layer  17  is an extruded adhesive resin between layers  16  and  18 . In the preferred embodiment, layer  17  is an ethylene and methyl acrylic copolymer. Layer  17  has a thickness of between 0.02 and 0.15 mm, and preferably a thickness of 0.07 mm. Layer  17  has a density in the range of 0.90 to 0.98 g/cm 3 , and preferably a density of 0.95 g/cm 3 . The ethylene methyl acrylate copolymer EMAC provided by Eastman Chemical Company, of 100 North Eastman Road, Kingsport, Tenn. 37662, may be employed in the preferred embodiment. It is contemplated that alternative adhesive resins, such as anhydride-modified polyolefin, anhydride-modified ethylene vinyl acetate, anhydride-modified low-density polyethylene, and anhydride-modified linear low-density polyethylene, may be employed. The Bynel® adhesive resin, provided by Dupont Packaging, of 1007 Market Street, Wilmington, Del. 19898, may be employed in such an alternative embodiment.  
         [0043]     Layer  18  is expanded polyethylene foam having a thickness of between about 1 and 6 mm, and preferably a thickness of about 4 mm. Layer  18  has a density of between about 4 to 10 lbs/ft 3 , and preferably a density of about 7 lbs/ft 3 . Layer  19  is also an expanded polyethylene foam. Layer  19  has a thickness of between about 1 and 20 mm, and preferably a thickness of about 2 mm. Layer  19  has a density in the range of about 1.6 to 4 lbs/ft 3 , and preferably a density of about 2.2 lbs/ft 3 . This dual polyethylene foam laminate sheet  18 / 19 , with outer layers of differing densities, between graphic film layer  17  and polyurethane core  20  facilitates a strong bond to the film and core layers, respectively. A higher density foam  18  is used next to graphic film layer  16  because this higher density foam  18  will bond better to the film layer, in part because it has a smoother outer surface. Using a lower density polyethylene foam sheet  19  next to polyurethane foam core  20  is beneficial in that this low density foam  19  will melt faster to polyurethane core  20  and therefore provide a faster bond.  
         [0044]     Layer  20  is polyurethane foam, and acts as the core of board  15 . Layer  20  has a thickness of between about 5 and 45 mm, and preferably a thickness of about 18 mm. Layer  20  has a density in the range of about 6 to 30 lbs/ft 3 , and preferably a density of about 8 lbs/ft 3 . A polyurethane foam core provides improved rigidity and stiffness to the board.  
         [0045]     Layer  21  is expanded polyethylene foam. Layer  21  has a thickness of between about 1 and 20 mm, and preferably a thickness of about 3 mm. Layer  21  has a density in the range of about 1.6 to 4 lbs/ft 3 , and preferably a density of about 2.2 lbs/ft 3 . Layer  22  is also expanded polyethylene foam. Layer  22  has a thickness of between about 1 and 6 mm, and preferably a thickness of about 4 mm. Layer  22  has a density in the range of about 5 to 11 lbs/ft 3 , and preferably a density of 9 lbs/ft 3 .  
         [0046]     Bottom layer  23  is non-expanded polyethylene film. Layer  23  has a thickness of between about 0.3 and 1.5 mm, and preferably a thickness of about 0.5 mm. Layer  23  has a density in the range of about 0.91 to 0.96 g/cm 3 , and preferably a density of about 0.95 g/cm 3 .  
         [0047]      FIGS. 5-6  show an alternative embodiment  24  of the molded sports board. In this embodiment, board  24  has six laminated layers, rather than eight. Layers  25 - 28  are generally of the same structure and composition as layers  16 - 19 , respectively, of first embodiment  15 .  
         [0048]     Layer  29  is expanded polyurethane foam, and acts as the core of board  24 . Layer  29  has a thickness of between about 10 and 50 mm, and preferably a thickness of about 22 mm. Layer  29  has a density in the range of about 6 to 30 lbs/ft 3 , and preferably a density of about 8 lbs/ft 3 .  
         [0049]     Bottom layer  30  is non-expanded thermoplastic polyurethane (TPU) film. Layer  30  has a thickness of between about 0.3 and 2.0 mm, and preferably a thickness of about 0.7 mm. Layer  30  has a density in the range of about 0.96 to 1.16 g/cm 3 , and preferably a density of about 1.06 g/cm 3 . It is contemplated that other thermoplastic films may be used such as chlorinated polyethylene (CPE), chlorinated propylene (CPP), chlorosulfonated polyethylene (CSPE) and ethylene-propylene-diene copolymer (EPDM).  
         [0050]      FIGS. 7-8  show a third embodiment  31 . This embodiment has seven layers. Layers  32  and  33  are generally of the same structure and composition as layers  16  and  17  in the first embodiment.  
         [0051]     Layer  34  is expanded polyethylene foam. Layer  34  has a thickness of between about 4 and 10 mm, and preferably a thickness of about 7 mm. Layer  34  has a density in the range of about 1.6 to about 4 lb/ft 3 , and preferably a density of about 2.2 lb/ft 3 .  
         [0052]     Layer  35  is expanded polyurethane foam, and acts as the core of board  31 . Layer  35  has a thickness of between about 5 and 45 mm, and preferably a thickness of about 18 mm. Layer  35  has a density in the range of about 6 to 30 lbs/ft 3 , and preferably a density of about 8 lb/ft 3 .  
         [0053]     Layers  36 - 38  are generally of the same structure and composition as layers  21 - 23 , respectively, of second embodiment  24 .  
         [0054]     As shown in  FIG. 18 , the surface of the boards are deeply contoured. In the preferred embodiment, the depth  65  of a valley relative to its adjacent ridge ranges from between about 2 and 25 mm, and preferably about 7 mm, and the slope  66  between the two is in the range of about 45 to 80 degrees, and preferably about 75 degrees. The distance  67  between tops of adjacent ridges may vary from between about 12 and 200 mm. Even with this deep contouring, the layers have good bonding strength and the graphics are distinct and have good image resolution.  
         [0055]     Boards  15 ,  24  and  31  are formed in a series of steps. As shown in  FIGS. 9-14 , a metal mold is created to conform to the desired profile of the finished foam sports board. Mold  43  has a top portion  44  and a bottom portion  45 . As shown, top portion  44  has an inner surface  63  with a contour that includes a number of ridges or raised areas  59 ,  60  and valleys or indentations  61 ,  62 . The contours run not only transversely  60 ,  62  but also longitudinally  59 ,  61  across the surface  63  of portion  44 . In the preferred embodiment, bottom portion  45  has an inner surface  64  that is generally planar and does not contain such contours. The molds also provide the desired curvature to the board from tip to tail. During the molding process, longitudinal valleys  61  and transverse valleys  62  will form longitudinal ridges  55  and transverse ridges  56 , respectively, and longitudinal ridges  59  and transverse ridges  60  will form longitudinal valleys  57  and transverse valleys  58 , respectively.  
         [0056]     Once mold  43  is created, the board is formed in a series of steps, some of which may vary somewhat depending on the embodiment. For each embodiment however, a top and bottom sheet are first formed.  
         [0057]     For board  15 , layer  16  is imprinted with the desired graphics using a conventional imprinting procedure. Foam layers  18  and  19  are then heat laminated to each other using a conventional heat lamination method to form a foam laminate  18 / 19 . As shown in  FIG. 15 , film layer  16  is then thread from a top roll  46  and foam laminate  18 / 19  is fed from bottom roll  47 . As layer  16  and foam laminate  18 / 19  are fed from rolls  46  and  47 , respectively, resin  17  is extruded, using a conventional extrusion process, between the inner surface of layer  16  and the outer surface of layer  18  of foam laminate  18 / 19  to form a laminated sheet of layers  16 ,  17 ,  18  and  19 . With respect to board  15 , this is the top sheet  16 / 17 / 18 / 19  referred to below. Next, layer  21  is laminated to layer  22  using a conventional heat lamination method to form a foam laminate  21 / 22 . As shown in  FIG. 16 , foam laminate  21 / 22  is then fed from a top roller  48 , while film layer  23  is extruded, using a conventional extrusion process, onto the outer surface of layer  22  of laminate  21 / 22  to form a laminated sheet of layers  21 ,  22  and  23 . With respect to board  15 , this is the bottom sheet  21 / 22 / 23  referred to below.  
         [0058]     For board  24 , a laminated top sheet of layers  25 ,  26 ,  27  and  28  is formed using the same general procedure for forming the top sheet  16 / 17 / 18 / 19  with board  15 . The bottom sheet for board  24  is a single layer  30 , and is not necessarily a laminated sheet.  
         [0059]     For board  31 , the laminated top sheet of layers  32 ,  33  and  34  is formed using the same general procedure for forming the top sheet  16 / 17 / 18 / 19  with board  15 . However, for this embodiment, a single foam layer  34  is fed from roller  47 , rather than a two layered foam laminate  18 / 19  or  27 / 28  as with board  15  and  24 , respectively. The laminated bottom sheet of layers  36 ,  37  and  38  is formed using the same general procedure for forming the bottom sheet  21 / 22 / 23  with board  15 .  
         [0060]     Once these top and bottom sheets are formed, the top portion  44  and bottom portion  45  of mold  43  are separated and rotated such that portion  44  is at the lowest level and inner surface  63  faces upward to act as a tray upon which the other elements will be stacked, as shown in  FIG. 17   a . As shown in  FIG. 17   b . the respective top sheet is placed upside down on portion  44  of the mold  43  such that film layer  16 ,  25 ,  32  is against the inner surface  63  of the bottom portion  44  of mold  43 . A polyurethane forming mixture  50  is then applied to the foam layer  19 ,  28 ,  34  of the top sheet. In the preferred embodiment, this mixture  50  is applied using a conventional spray gun  51  and is formed from an isocyanate component and a polyol component, which are introduced through hoses  52  and  53  to spray gun  51  to form mixture  50 . The spraying is accomplished with this two component mechanical mixing spray gun. The isocyante and polyol components are mixed in a ratio of 1:1 by volume using a conventional proportioning equipment and then sprayed onto the inner surface of layers  19 ,  28  and  34  of the top sheets, respectively. In the preferred embodiment, this step is carried out with a tank temperature set at about 75° F., hose temperatures at 80° F., and a spraying pressure of approximately 1,500 pounds per square inch. An example of a typical formulation of the polyurethane mixture  50  employed to produce the urethane foam core is shown in the table below.  
                                                             By Weight                                        ISOCYANATE COMPONENT               Polymeric MDI (Diphenymethane Diisocyanate)   100 parts           (31.5% NCO)           POLYOL COMPONENT           Polyether Triol   93%            (370 OH#)           Glycol Crosslinker   2%           Alkylamines Catalyst   1%           Polyether-modified Polysiloxane   3%           Water   1%               100 parts                      
 
 The proportioning FPL mixer produced by Canon, of Via C, Colombo, 49 20090 Trezzano S/N, Milan, Italy, may be used in the preferred embodiment. 
 
         [0061]     Immediately after mixture  50  has been sprayed onto the inner surface of the top sheet, the bottom sheet is placed over the top sheet such that the mixture is between the inner surfaces of the top and bottom sheet, as shown in  FIG. 17   c . Bottom portion  45  of mold  43  is in turn placed over the bottom sheet. The top  44  and bottom  45  portions of mold  43  are then closed, forming a cavity  49  therebetween. Pressure is then applied to the mold by ramps to mate the two opposed mold portions  44  and  45 .  
         [0062]     As shown in  FIGS. 17   d  and  17   e , when the activated polyurethane mixture  50  between the top and bottom sheets expands to form a polyurethane foam core, it fills cavity  49  and forces the top and bottom sheets to conform to the contours of the inner surfaces  63  and  64  of top and bottom portions  44  and  45  of mold  43 , respectively. The molds are then allowed a short period of time to cool, after which the ramp pressure is released and the cured foam board is removed and the flash from the seam edge is trimmed.  
         [0063]     The sports board may further include one or more handles attached to the top surface of the board. The handles are generally attached to the board by snap-rivets and snap-posts passing through apertures in the board and coupled with the board through a flexible strap member.  
         [0064]     The method employed provides a fast curing process, which enables finished boards to be pulled from the mold after cooling for about 2 to 15 minutes. This is substantially shorter than the curing time required on conventional fiberglass reinforced polyester molding.  
         [0065]     The properties of the finished sports board may be varied from a more flexible board to a stiffer board by adjusting the density of the urethane foam. This production process results in greater efficiencies, with 20 or 30 foam boards being able to be produced per hour. Because chemical mixture  50  is completely encapsulated by the top and bottom sheets, the process does not require a mold releasing agent. The urethane mixture  50  inside the mold expands and fills up the mold cavity  49  very quickly, providing excellent wet-out to the mold surfaces and reproducing the detailed contours of the mold profile without substantial voids, pinholes or other surface defects that occur with conventional fiberglass reinforced products.  
         [0066]     The present invention contemplates that other many changes and modifications may be made. Therefore, while the presently preferred form of the sports board have been shown and described, and several modifications discussed, persons skilled in this art will readily appreciate that various additional changes and modifications may be made without departing from the spirit of the invention, as defined and differentiated by the following claims.