Abstract:
A midsole of a shoe with multiple layers in which at least one of the layers is wrapped in film in order to protect it from the elements, provide stability and also to provide some visual features.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to the structure of a midsole for a shoe. More particularly, the present invention relates to a midsole that has a soft layer wrapped in a protective, stabilizing and/or decorative film. 
         [0003]    2. Description of the Related Art 
         [0004]    Shoes are comprised of an upper, midsole and outsole. Shoes are designed for many purposes—from protection on the job, to performance during athletic activity on the track or court, to special occasions and everyday lifestyle. In order to achieve these purposes, shoes are made with different types of uppers, midsoles and outsoles that enable them to properly suit the activity. Midsoles are an integral part of the shoe and provide stability and cushioning to the user of the shoe. 
         [0005]    A shoe midsole may be designed with various considerations. Some of those considerations present limitations and disadvantages. In some applications, the midsole must have a soft element in order to facilitate a particular is walking motion. However, due do the soft element, stability is compromised. Furthermore, due to the material that the soft element is made out of, the soft part of the midsole can take on elements, such as water, that may cause chemical reactions and lead to the breakdown of the midsole. 
         [0006]    In general, most footwear functions to keep the foot properly and comfortably positioned, stabilized, and minimizes a tendency toward a medial and/or lateral rolling motion. Prior art midsoles which have a soft lower layer are unstable and therefore usually require stabilization material such as a shank piece or a relatively hard upper midsole layer. Prior art shoes have attempted to protect the entire midsole, but not in a dual durometer, two layer configuration. 
         [0007]    Modern midsoles can be comprised of multiple layers. In particular, some midsoles have layers having different durometers of hardness. A soft durometer layer for cushioning and a firmer durometer layer for stability. Materials used are generally comprised of elastomeric materials that would include polyurethane, polyester elastomer, fluoroelastomer, chlorinated polyethylene, polyvinyl chloride, chlorosulfonated polyethylene, polyethylene/ethylene vinyl to acetate copolymer, neoprene, butadiene acrylonitrile rubber, butadiene styrene rubber, ethylene propylene polymer, natural rubber, silicone rubber, polyethylene, synthetic rubber, sulfide rubber, nitrile rubber, halogenated butyl rubber, polyethylene glycol, and combinations thereof. Soft lower layers in general are not used exclusively as they are not stable and could cause discomfort, pain or injury if is not used in conjunction with a stabilization device, such as a shank piece or relatively hard upper midsole layer to support the lateral to medial motion of the foot. The stabilization device is made from a more dense material such as rubber, plastic, thermoplastic, which acts to control pronation and guide the wearer into the proper gait cycle. 
         [0008]    Furthermore, the elastomeric materials used for midsoles include foams that are susceptible to damage from the elements that can cause chemical reactions and lead to breakdown of the midsole. In particular, outside elements such as extreme heat or cold, hydrolysis, ozone oxidation, UV radiation, and acid rain can cause a chemical breakdown of the elastomeric materials used for midsoles, thus reducing the efficiency and lifespan of the midsole. 
         [0009]    Also, there is difficulty printing intricate patterns on elastomeric materials used for midsoles and it is costly to change the color of the elastomeric material to represent a different color for each shoe style. 
         [0010]    The present invention seeks to provide a soft midsole which is s wrapped in film to protect it from the elements and to increase stability. The film may also add a decorative component to the midsole by having colors and/or prints on it. 
       SUMMARY OF THE INVENTION 
       [0011]    It is an object of the present invention to have a midsole with a layer that is relatively soft that is wrapped in an impermeable film such as thermoplastic polyurethane, polyvinyl chloride, or polyolefin. 
         [0012]    In a preferred embodiment, the invention includes a midsole that is comprised of a distinct upper layer and a distinct lower layer. The layers may be made of elastomeric materials that would include polyurethane, polyester elastomer, fluoroelastomer, chlorinated polyethylene, polyvinyl chloride, chlorosulfonated polyethylene, polyethylene/ethylene vinyl acetate copolymer, neoprene, butadiene acrylonitrile rubber, butadiene styrene rubber, ethylene propylene polymer, natural rubber, silicone rubber, polyethylene, synthetic rubber, sulfide rubber, nitrite rubber, halogenated butyl rubber, polyethylene glycol, and combinations thereof. 
         [0013]    The lower layer, which may or may not be made of the same material as the upper layer, has a density that is less than the density of the upper layer and is sufficiently low in density and high in compressibility so as to allow the lower layer to compress and deform a higher, or greater, amount under a given weight than the upper layer would compress and deform under that same weight. 
         [0014]    Due to the low density of the lower layer, the layer is particularly susceptible to damage from the elements. Outside elements, if allowed to contact the lower layer or seep in between the layers may cause chemical reactions and lead to the breakdown of the midsole. In particular, outside elements such as extreme heat or cold, hydrolysis, ozone oxidation, UV radiation, and acid rain can cause a chemical breakdown of the elastomeric materials used for midsoles, thus reducing the efficiency and lifespan of the midsole. 
         [0015]    In order to prevent such damage, the soft lower layer of the midsole is wrapped in film in order to provide protection to that layer from the elements. The film could also provide a new pattern, design or color. 
         [0016]    Furthermore, when a soft midsole layer is used in a shoe, the user of the shoe may experience excess instability such that the user loses his balance and falls down. The wrapping of the soft midsole layer with a film counteracts this effect. The film confines the soft midsole layer and prevents excess deformation of that layer, thereby enhancing stability. 
         [0017]    The wrapping of the soft layer of the midsole in a film is typically done during the molding process. The film is positioned into the mold having a surface complementary to the desired predetermined surface shape of the midsole. The film may be applied in a vacuum mold. The vacuum mold forms the shape of the film so that it is in the desired shape of the midsole layer. The elastomeric material that makes up the midsole layer is poured inside the mold and inside the film that is formed to the desired shape of the midsole layer. 
         [0018]    The film used in the vacuum mold forming process is formed either to the side or upwards of the midsole layer. Any excess film is then either trimmed or folded over onto the top surface of the midsole layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    By way of example only, selected embodiments and aspects of the present invention are described below. Each such description refers to a particular figure (“FIG.”) which shows the described matter. All such figures are shown in drawings that accompany this specification. Each such figure includes one or more reference numbers that identify one or more part(s) or element(s) of the invention. 
           [0020]      FIG. 1  is an exploded view of the midsole. 
           [0021]      FIG. 2  is an exploded view of the lower layer and film. 
           [0022]      FIG. 3  is a cross section view of the lower layer and film. 
           [0023]      FIG. 4  is a cross section view of the lower layer and film. 
           [0024]      FIG. 4A  is a cross section view of the midsole. 
           [0025]      FIG. 5  is an elevation view of the midsole. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]    The invention will now be described with reference to the preferred embodiment shown in  FIG. 1 . This embodiment shows a midsole  101 , the upper layer of the midsole  100 , the lower layer of the midsole  102  and the film  104 . As used herein, “above” and “below” refer to relative locations of identified elements when a shoe and thus the midsole is in its normal, upright position as shown in  FIGS. 1 and 5 . 
         [0027]    The midsole  101 , as shown in  FIG. 1 , comprises an upper layer  100  and a lower layer  102 . The upper layer  100  may comprise a plurality of sub-layers. The upper layer  100  has a top surface  113  substantially opposite a bottom surface  115 . The upper layer  100  has a peripheral wall  103 . The lower layer  102  has a top surface  117  substantially opposite a bottom surface  121 . The lower layer  102  has a peripheral wall  105 . As shown in  FIGS. 1 and 5 , when the midsole is in its normal, upright position, the lower layer  102  is below the upper layer  100 . 
         [0028]    In the preferred embodiment, the upper layer  100  has a first density and the lower layer  102  has a second density that is less dense than the first density. The upper layer  100  has a first compressibility and the lower layer  102  has a second compressibility that is greater than the first compressibility. The compressibility of the lower layer  102  is relatively high. The upper layer  100  is typically made of elastomeric materials that would include polyurethane, polyester elastomer, fluoroelastomer, chlorinated polyethylene, polyvinyl chloride, chlorosulfonated polyethylene, polyethylene/ethylene vinyl acetate copolymer, neoprene, butadiene acrylonitrile rubber, butadiene styrene rubber, ethylene propylene polymer, natural rubber, silicone rubber, polyethylene, synthetic rubber, sulfide rubber, nitrile rubber, halogenated butyl rubber, polyethylene glycol, and combinations thereof. However, the upper layer  100  can be made from any other material without departing from the scope of the present invention. The lower layer  102  is made of a compressible and deformable yet resilient material which may or may not be the same material of which the upper layer  100  is made. The upper layer  100  has a bottom surface  115  that may be connected to the top surface  117  of the lower layer  102  by either friction and/or an adhesive, molding and/or other similar means. However, the upper layer  100  and lower layer  102  can be connected by other means, not connected at all, or connected only in part, without departing from the scope of the present invention. 
         [0029]    In the preferred embodiment, the bottom surface  121  and the peripheral wall  105  of the lower layer  102  are wrapped by film  104 . The film  104  may also overlap the peripheral wall  105  and extend to the top surface  117  of the lower layer  102 . The film may be wrapped by hand, through a molding process, a vacuum molding process or overlay. However, the film may be wrapped by other means without departing from the scope of the present invention. The film  104  may be made out of polyurethane, polyvinyl chloride, rubber, thermal plastic rubber or thermoplastic polyurethane. However, the film  100  can be made from any other material without departing from the scope of the present invention. The bottom surface  121  and peripheral wall  105  are wrapped by film  104 , prior to the lower layer  102  being connected to the upper layer  100 . 
         [0030]      FIG. 2  is an exploded view of the lower layer  102  and the film  104 . As shown, the film  104  is normally flat or in rolls. The film  104  can either be translucent, transparent, colored or patterned. The film  104  is applied to the bottom surface  121  and peripheral wall  1 . 05  of the lower layer  102  as described above. 
         [0031]      FIG. 3  shows a cross section view of the film  104  combined with the lower layer  102 , during the production process. As shown, the film  104  overlaps to the side of the lower layer  102  up the peripheral wall  104  and can be trimmed or folded over to the top surface  117  of the lower layer  102 . 
         [0032]      FIG. 4  is a cross section view of the film  104  combined with the lower layer  102 , during an alternative production process. As shown, the film overlaps upwards of the peripheral wall of the lower layer  102  and can be trimmed or folded over to the top surface  117 . 
         [0033]      FIG. 4A  is a cross section view of the film  104  combined with the lower layer  102 . During the production process, as shown, the film is folded upwards on the top surface  117  of the lower layer  102 . 
         [0034]      FIG. 5  is an elevation view of a preferred embodiment of the complete midsole  101 .  FIG. 5  shows the upper layer  100  placed on top of the lower layer  102  and film  104  combined together to form the complete midsole  101 . The midsole  101  is below a shoe upper (shown in phantom) in a complete shoe. The midsole  101  is above a shoe outsole (shown in phantom) in a complete shoe.