Abstract:
A gliding board, for sliding on water, snow and land, is constructed from polyethylene and polypropylene foams, in three-ply or more layers of constant density or different densities as a multi-layer reinforced core. The use of polypropylene foam layers encompassing the core together with the application of thermoplastic binding Layer in between each layer enhances greater cohesive characteristics to join foam materials with different properties.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to foam sports boards for recreational use having a laminated gliding board with a sandwich construction, based upon a low density polyethylene foam core and sandwich composite polypropylene foam skins. The present invention is a light-weight board that uses more durable and flexible materials and is able to create higher performance, shapes and designs for recreational use.  
       BACKGROUND OF THE INVENTION  
       [0002]     In the current market, the core and deck of most of the low-cost gliding boards are commonly made of polyethylene foam, a type of foam which has a moderate solidity. The reason being that the price of polyethylene foam is stable and reasonable, the solidity of the polyethylene foam is moderate (polyethylene foam is harder than ethylene vinyl acetate foam but softer than expanded polystyrene foam), and the processing of the material is much easier. Low density light weight polyethylene foam is comparatively reasonable but also carries an average solidity. Polypropylene foam, a different type of foam, favorably carries a greater solidity and is not detrimental by greatly increasing weight. Hence, when comparing two gliding boards which one of which is made of high stiffness foam and the other is made of low stiffness foam, the one made of high stiffness foam is more advantageous than the one made of low stiffness foam no matter the velocity or direction control of the gliding board.  
         [0003]     In a technical aspect, direct rigidity enhancement to the core of a polyethylene foam gliding board is often complicated and difficult to accomplish. Although polyethylene is the preferred foam for use in manufacturing sports boards, there exist many deficiencies that occur with this type of material. Polyethylene foam carries a tendency to lose shape and solidity after long term use and exposure to the sun. Therefore, when attempting to correct these features, augmentations should focus on the surrounding areas (the deck and bottom layer) of the foam, for example adding further layers to protect this foam. Polyethylene foam also has a considerably greater mass. Polypropylene foam, a different type of foam with comparatively similar features is less commonly used for manufacturing sports boards as it is more costly. However, this type of foam carries a one hundred percent greater solidity and a thirty to fifty percent lighter weight than polyethylene foam. In order to compensate for the cost aspect of using this type of foam, polypropylene foam will be used in a lesser amount, and placed as a protective layer surrounding the polyethylene foam. Conclusively, polypropylene foam material is exceptionally suitable for the surrounding layer of polyethylene foam core as it will appreciably strengthen the solidity of a common gliding board.  
         [0004]     However, with bonding two foam layers of different characteristics, specific work processes are needed. It is known that heat may directly be used to bond different layers together, however, the thermal laminating process usually requires complex procedures and carries risks such as undesirable shrinking of the layers. A more favorable process would involve a thermoplastic binding layer of adhesive resin, for example metallocene catalyst, which is pre-heated and applied to the surface of one of the foam layers. After the lamination, the quality of the entire foam layer is significantly improved: solidity increasing by ten per cent to thirty per cent and weight reducing five per cent to twenty per cent.  
       SUMMARY OF THE INVENTION  
       [0005]     The primary objective of the present invention is to provide an improved gliding board made of compound foam materials in order to resolve the limitations of a loss of solidity and a decrease of function. This present invention is a gliding board with a greater firmness and cohesion of structure without an increase in weight.  
         [0006]     In a second aspect, the present invention fully utilizes the characteristics of different foam material in the arrangement and the construction of a gliding board.  
         [0007]     In a third aspect, the present invention allows a variety of foam materials in the composition of the core, deck, stronger layers, concord layer and bottom solid sheet of a gliding board. The use of thermoplastic binding layers creates a durable and secure organization of core layers and provides a better performance of gliding boards. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a cross-sectional view of new invention gliding board structure with deck and concord layer.  
         [0009]      FIG. 2  is a cross-sectional view of new invention gliding board structure with plastic polymer graphic film underneath board core.  
         [0010]      FIG. 3  is a cross-sectional view of a second embodiment of new invention gliding board structure.  
         [0011]      FIG. 4 ( a ) is a partial schematic view of the new methodology of bonding of plastic polymer graphic film to deck or outer core of the present invention.  
         [0012]      FIG. 4 ( b ) is a partial schematic view of the new methodology of viscose of a polypropylene/polyethylene/ethylene vinyl acetate board core of the present invention.  
         [0013]      FIG. 4 ( c ) is a partial schematic view of the method of manufacturing of gliding board of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]     The invention is described in connection with certain preferred embodiments, i.e. using a pair of polypropylene foam layers to sandwich the core in order to enhance the rigidity, and using compound thermoplastic substance to laminate foam Layers of different category. It is to be understood that the present invention is not to be limited to any particular construction of the reinforced core of the gliding board, or to the use of any particular kind of compound thermoplastic substance in bonding the reinforced core of the gliding board. The compound thermoplastic substance may be varied in accordance with the category, grade, property and density of the foam materials composing the reinforced core, stronger layers and concord layer of the gliding board. In addition, the present invention is not limited to any particular construction of the gliding boards shown in the figures and may be of any configuration as is known in the art. Throughout the descriptions, the arrangement of the layers are described using terms “top” and “bottom” and “upper” and “lower”. In order to further clarify the location of the layers, the terms “top” and “upper” as well as “bottom” and “lower” describe the locations as they are illustrated in the drawings. The terms “outer” and “inner” are also used to describe the location of the layers, “outer” meaning further from the core, and “inner” signifying  
         [0015]      FIG. 1  shows a cross-sectional view of the structure of the present invention with which seven layers of different foam materials constitute the gliding board. This gliding board has a core represented by  13   a , laminated by a pair of stronger layers  13   b ,  13   c  with two thermoplastic layers  16   c ,  16   d  as bonding agents forming a reinforced core  13 , a deck foam  12  laminated on top of reinforced core  13 , a concord layer  14  laminated to the inner surface reinforced core  13 , a plastic graphic film  11  laminated on top of the deck foam  12  with a thermoplastic binding layer  16   a  as bonding agent, and a slick (bottom solid sheet)  15 .  
         [0016]     The core  13   a  is closed-cell low density polyethylene or polystyrene foam, having a thickness of 20 to 80 mm and a density of 1.5 to 4 lbs/ft 3 . Stronger layers, marked by  13   b  and  13   c , are closed-cell high density polypropylene foam, each having a thickness of 1.5 to 5 mm and has a density of 4 to 9 lbs/ft 3 . The stronger layers serve as the covering of the core  13   a  functioning to enhance the rigidity of the core of the gliding board. In order to laminate the core  13 a of polyethylene foam and a pair of the stronger layers of polypropylene foam  13   b  and  13   c , a pair of thermoplastic binding Layers  16   b ,  16   c  are applied, in manner of extrude coating, to the upper surface  21  and lower surface  17  of the stronger layer  13   b . Similarly, another pair of thermoplastic binding layers  16   d ,  16   e  is applied to the upper surface  18  and lower surface  23  of the strong layer  13   c . Thereafter, the said pair of stronger layers  13   b  and  13   c  are laminated to the core  13   a  in such a manner that the core  13   a  is the center of the layers, and sandwiched by layer  13   b  and layer  13   c , by heat lamination and to a form a reinforced core  13 . The functions of the thermoplastic substance not only to fill in the air cells on the surface of polypropylene board core and to enhance the stiff of the board, but also the cohesive agent to get two different foam layers firmly united.  
         [0017]     Furthermore, thermoplastic binding layers  16   c  and  16   d  also function as the cohesive agent with the core  13   a  and the layers  13   b  and  13   c  to achieve a secure and durable structure. Thermoplastic binding layers  16   b ,  16   c ,  16   d  and  16   e  are selected from a compound thermoplastic substance #1818, which is comprised of low density polyethylene, ethylene vinyl acetate and tackifying resin; substance #2828, which is comprised of metallocene-catalyzed resin and polyethylene; and substance #6868, which is comprised of anhydride-modified ethylene vinyl acetate polymers. Each thermoplastic binding layer has a thickness of approximately 0.02 to 0.10 mm.  
         [0018]     Deck  12  may be closed-cell high density ethylene vinyl acetate foam or high density polyethylene foam which has a thickness ranging from 1 to 5 mm and a density ranging from 4 to 10 lbs/ft 3 . If deck  12  is made of ethylene vinyl acetate, it has a hardness ranging from 35 to 65 degrees. Being that deck  12 , stronger layer  13   b  and the top plastic film  11  are different foam materials, and a thermoplastic binding layer  16   b  has already been coated onto the outer surface  21  of the stronger layer  13   b , another thermoplastic binding layer  16   a  must be applied to the outer surface  19  of the deck  12  as they serve as cohesive agents. By heat lamination, deck  12  is jointed to top plastic graphic film in such a manner that thermoplastic binding layer  16   a  is the center of two layers and sandwiched by layer  11  and layer  12 .  
         [0019]     Concord layer  14  is closed-cell high density polyethylene foam which has a thickness ranging from 1 to 5 mm and a density ranging from 4 to 10 lbs/ft 3 . This layer is to be bonded to the lower surface  23  of the reinforced core  13  by heat lamination. The reason being that the surface of the reinforced core  13  is made of polypropylene foam, a thermoplastic binding layer  16   e  is adopted to the outer surface  24  of the concord layer  14  for agglutination. The slick  15  is made of high density polyethylene and carries the form of a solid sheet. The solid sheet  15  has a thickness in the range of 0.1 to 1.5 mm. A process of heat-lamination is then used for bonding the concord layer  14  to the lower surface  23  of the reinforced core  13  and to the solid sheet  15  simultaneously. The rigidity of the board is enhanced with the ancillary of deck  12  and concord layer  14 .  
         [0020]      FIG. 2  shows a cross-sectional view of another structure of the invention. The structure of this gliding board consists of layer  23  acting as a core, a pair of stronger layers  22  and  24 , top plastic film  21 , a concord layer  25 , and a slick (bottom solid sheet)  26 . Similarly, the core may be closed-cell low density polyethylene foam or polystyrene having a thickness from 20 to 80 mm and a density ranging from 1.5 to 4 lbs/ft 3 . Similar to the embodiment in  FIG. 1 , core  23  is surrounded by stronger layers  22  and  24 . The stronger layers are closed-cell high density crosslink or non-crosslink polypropylene foam having a thickness in the range of 1.5 to 5 mm and a density ranging from 4 to 9 lbs/ft 3 . A pair of thermoplastic binding layers  27   a  and  27   b , respectively, are applied to the upper surface  29   c  and lower surface  29   a  of stronger layer  22 . Similarly, another pair of thermoplastic binding layers  27   c ,  27   d , respectively, are applied to the upper surface  29   b  and lower surface  29   d  of stronger layer  24 . Thermoplastic binding layers  27   b  and  27   c  serve to bond the core  23  and stronger Layers  22  and  24 . The thermoplastic substances applied in this embodiment are the same as illustrated in  FIG. 1 . A heat lamination method bonds layers  23 ,  22  and  24 , and subsequently forming a reinforced core  28 . A polyethylene plastic film  25  having graphic imprinted on the lower surface is adhered to the bottom surface  29   d  of the reinforced core  28 . The plastic film layer  25  is closed-cell high density polyethylene foam having a thickness in the range of 0.02 to 0.15 mm. As mentioned above, a thermoplastic binding layer  27   d  is previously adhered to the lower surface  29   d  of the reinforced core  28 . Thereafter, heat lamination processes bond the top plastic film  21  from the top and the slick  26  to form the gliding board. Slick  26  is high density polyethylene foam and top plastic film  21  is selected from polypropylene, PET and polyethylene foam in single or dual-layers. In this invention, graphics on both sides of the gliding board can be seen.  
         [0021]      FIG. 3  shows a cross-sectional view of a third embodiment of the present invention of a gliding board. Similar to the embodiment in  FIG. 2 , the construction of this embodiment has a reinforced core  38  comparable to reinforced core  28 . Conversely, with the exception of reinforced core  38 , the foam layers in this arrangement consist largely of polypropylene material. A dual-layer top plastic film with printing represented by layer  31  consists of polypropylene and is adhered to the upper surface  39   c  of the reinforced core  38  by heat lamination without the aid of thermoplastic substance. Similarly, another plastic film layer  35  and a slick of polyethylene  36  are adhered to the bottom surface  39   d  of the reinforced core  38  also without the aid of thermoplastic substance by heat lamination simultaneously when bonding the top plastic film  31 . Top plastic film  31  has a thickness ranging from 0.03 to 0.1 mm. The slick  36  has a thickness ranging from 0.1 to 1.5 mm.  
         [0022]      FIG. 4   a  illustrates a schematic view of the methodology of bonding top plastic graphic film  41  to a high density polypropylene or polyethylene or ethylene vinyl acetate deck  44  in the present invention. By shoving the compound thermoplastic substance #1818 which contains ethylene vinyl acetate copolymer and tackifying resin, or substance #2828 which contains metallocene-catalyzed resin and polyethylene; or substance #6868 which contains anhydride-modified ethylene vinyl acetate polymer into furnace  45  with a high temperature of 180 to 200 degrees, and thereafter passing through a T-die  46  for injection. A layer of compound thermoplastic substance is in between the plastic film  41  and deck  44  which are both in roll format and to be bonded and pressurized by the upper embossing or nip roller  42  and a lower nip roller  43  for reinforcement of the stiffness of the graphic film  41  to the deck  44 .  
         [0023]      FIG. 4   b  illustrates a schematic view of the new methodology of viscose of the board core layers of the invention. Similar to the procedure in  FIG. 4   a , by shoving the thermoplastic substances (#1818/ #2828/ #6868)  50  into the furnace  51  with a high temperature of 180 to 200 degrees, and thereafter passing through a T-die  52  for injection, a layer of thermoplastic substance  56  is on the surface of the polypropylene or polyethylene or ethylene vinyl acetate foam board  55  which is exported from a roll format and to be bonded and pressurized by the upper roller  53  and a lower roller  54  for reinforcement of the stiffness of the board. The same procedure will be repeated when the thermoplastic substance need to be coated on both sides of the foam layer.  
         [0024]      FIG. 4   c  is a schematic view of the method of manufacturing a gliding board of the invention. By applying a heat lamination method through the febrifacient  61  and pushing through the pair of rollers  63 ,  64  for pressurizing, to bond the synthesizer of top plastic film and the deck  60  to the synthesizer of reinforced core, the concord layer and the high density solid sheet  65 . Thereafter, behind the rollers  63 ,  64 , the outer core  60  and board core  65  are pressed to have a curved shape at the front of the board, and the semi-product of the gliding board  66  will be processed afterwards by further heat lamination to extend the graphic film from top to the bottom of the solid sheet to form the gliding board.  
         [0025]     The foregoing description should be considered as illustrative only of the principles of the invention. Since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents, including the composition by means of the number of layers, the densities of the foam materials and the thickness of each layers, may be resorted to, falling within the scope of the invention.