Abstract:
A method of manufacturing a flexible, impact-resistant material includes the steps of providing a sheet of a closed-cell foam material and cutting the sheet into at least two tessellating patterns, preferably by a cutter. The tessellating patterns are then differentially moved relative to one another such that the surface of one of the tessellating patterns stands proud of the surface of the other tessellating patterns. A first, flexible layer of material is then bonded to the surface of the tessellating pattern standing proud of the rest. Preferably, a block arrangement is located in the cutter that causes the tessellating patterns to move relative to one another after the sheet of foam material has been cut.

Description:
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT Not applicable. 
     REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present invention relates to a method of manufacturing a flexible, impact-resistant laminate and to a laminate produced by such a method. 
         [0006]    2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
         [0007]    Such laminates are widely used as protective material which is incorporated into clothing and the like to fashion protective wear for human and animal bodies. Such protective wear is used during sport, rugby for example and equestrian sports and in other activities where a person runs a risk of injury, for example building and other trades. 
         [0008]    Conventional protective wear may form an integral part of an item of clothing, for example a shoulder pad, or be provided separately, for example a shin pad. 
         [0009]    In EP 1194050 a method of manufacturing a flexible laminate is described, comprising the following steps: 
         [0010]    1. providing a sheet of a resilient material, such as a closed cell foam; 
         [0011]    2. cutting the sheet into a plurality of spaced, separate elements using a cutter which is pressed into the sheet to cut therethrough; 
         [0012]    3. making one side of the spaced elements to stand proud of the surface of a jig provided to hold the elements in place; 
         [0013]    4. removing excess resilient material from between the spaced, separate elements; and 
         [0014]    5. bonding a flexible, resiliently stretchable substrate to one side of the separate elements by heating the substrate either to activate an adhesive applied between said one side of the separate elements and the substrate or to fuse the elements to the substrate. 
         [0015]    In this method, the cutter acts as the jig after cutting through the resilient foam to hold the elements in place while the substrate layer is applied thereto. Prior to this, excess material from between the elements is removed before the bonding of the spaced elements to the substrate. Such excess material is then scrapped. 
         [0016]    The object of the present invention is to provide an improved method of manufacturing the flexible material. 
       BRIEF SUMMARY OF THE INVENTION 
       [0017]    According to a first aspect of the present invention there is provided a method of manufacturing a flexible, impact-resistant material comprising the steps of providing a sheet of a closed-cell foam material; cutting the sheet into at least two tessellating patterns; differentially moving the tessellating patterns relative to one another such that the surface of one of the tessellating patterns stands proud of the surface of the other tessellating patterns; providing a first, flexible layer of material; and bonding a first of said tessellating patterns to one side of the first layer of material. 
         [0018]    It will be appreciated that in this method excess material from between the elements is not removed before the spaced elements are bonded to the flexible layer of material that forms substrate. Bonding of the elements to the material takes place first and excess foam material can then be scrapped. However, by appropriate design of the tessellating patterns the foam material forming the second and any subsequent patterns need not be scrapped but used to form another sheet of flexible, impact-resistant material. This greatly increases the efficiency of the process and reduces waste because all of the closed-cell foam material can be used rather a proportion of it being scrapped. This saves cost in addition to preventing unnecessary waste. The manufacturing process is also speeded up. 
         [0019]    Preferably, the sheet of closed-cell foam is cut into the tessellating patterns using a cutter which is pressed into the foam to cut therethrough. 
         [0020]    Preferably also, the cutter is adapted so that after the sheet of closed-cell foam has been cut all of the tessellating patterns stand proud of the surface of the cutter grid. 
         [0021]    Preferably also, a block arrangement is located within the cutter that causes the tessellating patterns to move relative to one another after the sheet of foam has been cut. 
         [0022]    Preferably also, the cutter comprises a plurality of cutter blades each with a polygonal or closed curve profile that are mounted on a board, a block being located within each of the cutter blades that defines an exposed surface at a level higher, relative to the cutter blades, than the level of the board surrounding the cutter blades. 
         [0023]    Preferably also, the cutter is adapted so that after the sheet of closed-cell foam has been cut all of the tessellating patterns stand proud of the cutter. 
         [0024]    Preferably also, opposing faces of the sheet of closed-cell foam material are coated with a hot-melt adhesive prior to the sheet being cut into said tessellating patterns. 
         [0025]    Preferably also, the method comprises the additional step of bonding the closed-cell foam comprising one of the tessellating patterns to one side of a second flexible layer of material on the other side of the laminate to the first layer of material after the foam material defining said one tessellating pattern has been removed from contact with the other tessellating patterns. 
         [0026]    Preferably also, the method comprises the additional steps of providing a third flexible layer of material and bonding a second tessellating pattern to one side of the third layer of material after the foam material defining the first tessellating pattern has been removed therefrom to create a second flexible, impact-resistant laminate. 
         [0027]    Preferably also, the flexible layers of material to which the closed-cell foam is bonded comprise at least one of the following, namely a resiliently stretchable fabric, a knitted fabric, a woven fabric, a plastics sheeting. 
         [0028]    According to second aspect of the present invention there is provided a flexible, impact-resistant laminate manufactured in accordance with the first aspect of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0029]    The various aspects of the present invention will now be described by way of example with reference to the accompanying drawings. 
           [0030]      FIG. 1  is a perspective view of a flexible, impact-resistant laminate manufactured in accordance with the method of the present invention. 
           [0031]      FIG. 2  is a top plan view of a sheet of closed-cell foam cut into two tessellating patterns in accordance with the method of the present invention. 
           [0032]      FIG. 3  is a top plan view of a cutter for use in the method according to the present invention. 
           [0033]      FIG. 4  is a vertical cross-sectional view, to an enlarged scale, through part of the cutter as shown in  FIG. 3 . 
           [0034]      FIGS. 5 to 8  are schematic views of a series of diagrams showing various stages during the manufacture of a laminate as shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    As shown in  FIG. 1 , a flexible, impact resistant laminate manufactured according to the present invention comprises a plurality of elements i of a resilient closed-cell foam fused to or joined by an adhesive to a flexible layer of material  2 . The elements  1  are evenly arranged, each element  1  being spaced from adjacent elements  1  by between 1 mm and 4 mm. 
         [0036]    In the embodiment illustrated, a margin of material  2  is provided around the periphery of the elements  1  and along the edges of the material at opposite ends respectively there are strips  3  of VELCRO (™), only one of which is shown. These strips  3  can be used to join a piece of the laminate together, for example to for a wrist band or shin pad. 
         [0037]    Alternatively, the edges of the laminate can be sewn or otherwise secured to clothing parts or other material dependent on the use to which it is to be put. 
         [0038]    Advantageously, the closed-cell foam is a polyethylene foam and the elements  1  comprise cubes which are evenly distributed with a density of between 100 and 8000 cells or elements/m 2 . For some applications, the density can be lower than for protective wear as the greater the density, the greater the flexibility of the laminate. For protective wear a density between 2000 and 6000 elements/m 2  is preferable as it allows the laminate to flex easily in all directions without “locking up” or preventing movement in a particular direction. Also, it enables the laminate to be cut into small pieces, for example to form protective wear of different sizes, without significantly affecting its ability to flex. 
         [0039]    Although the elements  1  are shown as cubes in  FIG. 1 , the foam can be cut into other shapes, an hexagonal shape being preferable for some applications. 
         [0040]    If the laminate is to be used in the production of protective wear or upholstery, the material  2  is preferably made of a resiliently stretchable knitted fabric, advantageously one comprising polyester or elastane fibers. However, in other applications, the material  2  can be made of a hard-wearing knitted or woven fabric or film, that does not need to be stretchable. Suitable films include plastics films such as sheets of polyethylene or polyurethane. 
         [0041]    In some applications, a second layer of flexible material is bonded over the elements so that they are sandwiched between two layers. In this case, if the first layer of material is resiliently stretchable or elastic, this helps to prevent puckering of one side of the laminate when it is flexed. 
         [0042]    Advantageously, however, both the outer layers of material are resiliently stretchable. In cases where only a single stretchable layer of material  2  is provided and the laminate is to be used in a curved configuration, for example in protective clothing, the laminate is preferably arranged so that the stretchable material layer lies on the outside surface of the curve. 
         [0043]      FIG. 3  shows a plan view of a first embodiment of cutter io used in the manufacture of the material shown in  FIG. 1 . The cutter io comprises a plurality of blades ii with a polygonal or closed curve profile that are mounted on a board  12 . In the present embodiment the blades  11  each define a rectangular profile which determines the size of the elements  1 . If the laminate material is for use in protective wear, for example, the blades  11  may have sides that are 12 mm long with corners of radius 2.5 mm. However, it will be appreciated that any appropriate blade profile  11  could be used. Also, the height of the blades  11  of the cutter  10  are arranged to be slightly smaller than the thickness of foam sheet with which the cutter  10  is to be used. This means that when the cutter  10  is used to cut a sheet of foam as shown in  FIG. 2 , the foam is cut into two tessellating patterns comprising a cellular matrix  8  and a regular series of elements  9  comprising blocks or cubes  18 . 
         [0044]      FIG. 4  is a diagram showing a vertical section through one of the blades  11  and the surrounding board  12 . It can be seen that within each of the cutter blades  11  is a block  13  which has an exposed surface at a level higher relative to the blades  11  than the level of the board  12  surrounding the blades  11 . This means that after cutting of the sheet of foam, the foam cubes  18  within the blades  11  are raised above the level of the matrix  8  after cutting. The reason for this will now be explained and the steps involved in manufacturing a laminate using the cutter shown in  FIGS. 3 and 4  will now be described with reference to the sequence of drawings as shown in  FIGS. 5 to 8 . 
         [0045]    First, both sides of a sheet  15  of closed cell foam are coated on both sides with a hot melt adhesive  16 . The foam  15  is then placed over a cutter  10 , of the type shown in  FIGS. 3 and 4 , and either pressed down with a press  17 , as shown in  FIG. 5 , or passed through nip rollers (not shown) so that the cutter  10  cuts through the foam  15  to form a cellular matrix  8 , as shown in  FIG. 2 , and a plurality of separate cubes  18 . Once the press  17  is removed, owing to its springy nature the foam  15  will tend to spring back slightly so that its upper surface stands proud above the upper surface of the cutter  10  as defined by the edges of the blades  11 . However, as the foam cubes  18  within the blades are supported by the blocks  13  at a higher level than the cellular matrix  8 , the cubes  18  stands proud of the surface of the matrix  8  as shown in  FIG. 7 . The cutter  10  therefore acts as a jig, holding the cut foam in position during the next stage of the manufacturing process. 
         [0046]    Next, as shown in  FIG. 6 , a first layer of material  19  is placed over the foam  15  and the cutter  10 . In view of the difference in height between the cellular matrix  8  and the cubes  18 , the inner surface of the material  19  only contacts the upper surface of the cubes  18 . A heated platen  20  is now brought into contact with outer surface of the material  19  and heat is conducted through the material  19  to the foam of the cubes  18  which activates the adhesive coating  16 . This bonds the material  19  to the cubes  18  but not to the cellular matrix  8 . Heated nip rollers (not shown) could be used in place of the platen  20 . Once the adhesive has been activated, the material  19  can be lifted away from the cutter  10  taking the cubes  18  with it and leaving the cellular matrix  8  behind, as shown in  FIG. 7 . The cellular matrix  8  could now be scrapped. 
         [0047]    Preferably, however, the cellular matrix  8  is then also bonded to another layer of flexible material  19  in exactly the same way as the cubes  8 . Hence, none of the foam sheet  15  is wasted, which is advantageous because it is both expensive to produce and to dispose of as a waste product. It will be appreciated, therefore, that preferably the cutter  10  is adapted to cut the foam sheet  15  into two tessellating patterns which are both suitable for use in the production of a useable laminate, each pattern having foam regions that are neither too small nor too narrow to be practical. For example, the patterns may comprise one which forms a cellular matrix and the other foam elements, as in the illustrated embodiment, or both could form elements in a checkerboard pattern or similar with square or other polygonal shapes. The patterns may also define stripes or swirling patterns. The patterns could also be specially adapted and bespoke for particular applications of the laminate as such a laminate will have different properties in different areas and when flexed in different directions. 
         [0048]    It is also conceivable for more than two tessellating patterns to be cut and two series of blocks  13  of different heights arranged in the cutter  10  so that each pattern is raised by a different amount to enable each foam pattern to be individually bonded to a separate layer of material  19 . 
         [0049]    As shown in  FIG. 8 , once the foam cubes  18  or cellular matrix  8  have been bonded to a first layer of material  19 , a second layer of a flexible material  22  can be then bonded to the other side of the foam by supporting the laminate on a board  21  and using a heated platen  20  or heated nip rollers (not shown) in the same way as for the first layer of material  19 . 
         [0050]    Variations to the above method are possible, for example the closed-cell foam may be fused to the layers  19  and  22  by the application of heat so that it partially melts on the surface rather than being adhered thereto. In addition, other impact resistance materials, such as an elastomeric material, could be used to fill the spaces between the regions of closed-cell foam.