ONE-PIECE SHOE WITH BOTTOM SOLE INSERT

BACKGROUND OF THE INVENTION

One-piece shoes are known in the art. These shoes result from a very efficient manufacturing process, such as that disclosed in US patent number 6,993,858 ("the '858 patent"), which is incorporated herein by reference. The '858 patent discloses a shoe that, if the strap is not included, is not only a one-piece shoe, but is also exceptionally light in weight as a consequence of its foamed plastic composition.

While the use of foamed plastic results in a very light weight shoe, it does not intrinsically result in a durable shoe. Processes can be applied to the shoe that result in a relatively tough outer skin to increase durability, but such surface treatments are subject to abrasive wear, which cause premature failure of the shoe. Thus, while such treatments are sufficient for lower wear areas of the shoe, such as the inner sole, the inner surfaces of the upper, or the toe box, they are generally not sufficient for the outer sole that is subject to abrasion from regular ground contact.

SUMMARY OF THE INVENTION

The invention is directed to providing a means for increasing the functionality of one-piece shoes, and particularly to the outer sole areas of such shoes. As opposed to prior art efforts that focused on surface or skin treatment of the outer sole of such shoes, shoe embodiments of the invention comprise at least one recess formed in the outer sole, later occupied by a tread insert. The at least one recess is preferably created at the time of shoe formation, and most preferably occurs during the injection molding process. The at least one recess can be of any geometric configuration, and can extend across the outer sole to locations adjacent to and/or extending past the outer periphery of the outer sole. While permitting the recess to exceed the periphery of the outer sole is considered within the scope of the invention, if the recess is kept within the periphery of the sole, the interface between the tread insert and the recess (and particularly the

vulnerable lateral interface) is protected from the environment and not laterally visible when the shoe is in use.

Tread insert embodiments of the invention are intended to closely fit within the at least one recess formed in the shoe. An adhesive/solvent (or combinations of adhesives/solvents) is preferably used to secure the tread insert to the shoe, although other means of fixation may be used and include non-chemical welding (or a subsequent injection molding process) or mechanical fastening. The tread insert embodiments are preferably about 5 mm in thickness, and are constructed from natural and/or synthetic rubber, for example, thermoplastic rubber ("TPR"), although the skilled practitioner would appreciate the use of alternative materials and equivalents. If a light weight shoe embodiment of the invention is desired, select use of the tread inserts is desirable. Thus, both the geometric use of the insert {e.g., the area and depth of the tread insert) and the composition of the insert {e.g., density, durability, etc.) will be evaluated and balanced against the objective of light weight.

When a tread insert is securely mated with a one-piece shoe having a complementary recess formed therein, the resulting combination maintains the advantages of a light, one-piece shoe with the advantages of a sole having increased performance factors, such as traction and importantly, durability. By intelligently locating the recesses on high load and/or high abrasion areas of the sole, and selecting a suitable material for construction of the tread inserts, one can achieve a shoe that will far outlast one piece shoes of the prior art.

As noted above, it is considered preferable to have the at least one recess perimeter be continuous, i.e., the at least one recess perimeter does not exceed the outer sole periphery. However for fashion or manufacturing reasons, it may be desirable to have the at least one recess breach the outer sole periphery. If the tread insert is constructed from a substance that is color contrasting with the outer sole, having a peripheral exposure would alert others to the presence of the insert without having to expose the bottom sole. Moreover, if a plurality of such breaches are present, a pattern can be formed, which may be desirable for less functional reasons. In addition, the invention contemplates the creation or

incorporation of an abrasion strip that is exterior of the outer sole periphery when associated with the shoe, yet extends from the tread insert so that the tread insert and the abrasion strip constitute a single piece of material. The abrasion strip or lateral bumper may be coextensive with the perimeter of the shoe or may occupy a portion thereof. The abrasion strip may extend from the tread insert in a contiguous manner or may extend there from in a segmented manner. Adhesive preferably secures the abrasion strip to the outer sole periphery and lateral portions of the shoe.

The tread insert(s) may have surface features that are the same as, similar to, or contrast with surface features associated with the outer sole. For example, a "snow shoe" version may have large lugs located on the periphery of the outer sole while the at least one tread insert has a smoother surface with sipes for better traction on smooth and wet surfaces, often encountered indoors from a winter environment, or vice versa. In addition, compound adjuncts may be used to enhance the functional aspects of the tread insert, without affecting the comfort/quality of the shoe. Examples of this approach would include a tread insert comprising silica or crushed walnuts that significant increase durability and/or traction, but if present on the inside surface of the sole, would significant adversely impact shoe comfort. In many embodiments, there are two tread inserts, namely, a ball tread insert and a heel tread insert. While a single recess and single tread insert is clearly within the scope of the invention, bifurcating the tread insert permits greater design flexibility, reduced material consumption and reduced weight. For instance, the heel tread insert can be of a first composition while the ball tread insert can be of another. The choice of compositions may affect the wear resistance of the tread insert, the flexibility of the tread insert, the color of the tread insert, the "feel" of the shoe in which the inserts are disposed (orthopedic factors), and other characteristics known to those persons skilled in the art. Finally, it should be apparent that any number of recess and insert combinations can be reasonably employed in a one-piece shoe.

In addition to the foregoing, the tread insert(s) need not be homogeneous; embodiments of the invention provide for zoned tread inserts and/or laminated inserts where areas of differing mechanical properties can be realized, depending upon performance and cost considerations. Finally, the term "one-piece shoe", as used herein, refers to any injection molded or single step formation shoe, such as the Holey Soles ^tm or Crocs ^tm brand shoes, regardless of whether straps or other structure is subsequently attached.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of a one-piece shoe having tread inserts integrated therein;

Fig. 2 is an exploded view of the embodiment shown in Fig. 1 ;

Fig. 3 is a side elevation view in partial section illustrating the relationship between the recesses and the tread inserts; and

Fig. 4 is a plan view of the embodiment shown in Fig. 1.

DESCRIPTION OF THE INVENTION EMBODIMENTS

The following discussion is presented to enable a person skilled in the art to make and use the invention. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention as defined by the appended claims. Thus, the present invention is not intended to be limited to the embodiments show, but is to be accorded the widest scope consistent with the principles and features disclosed herein. Turing then to the several Figures wherein like elements or parts are given like numbers, and more particularly to Figs. 3 and 4, a perspective view of a one- piece shoe having tread inserts integrated therein is shown. Shoe 10 comprises sole 20, which has inner surface 22 (see Fig. 3), outer surface 24, toe portion 26, ball portion 28, instep or arch portion 30 and heel portion 32. In addition, shoe 10

further comprises sidewall 40, which includes toe portion 42, lateral portion 44 and heel portion 46. Sidewall 40 generally refers to that portion of shoe 10 that is between the sole and the upper or vamp, and which extends about the perimeter of the shoe. At a minimum, the sidewall includes that portion of the shoe exterior that is between the inner surface and outer surface of the sole. All "portions" referenced herein do not perse represent discrete elements or boundaries of shoe 10, but instead are presented for reference purposes only unless otherwise indicated.

Shoe 10 may be molded to provide recesses 12a and 12b, or these recesses may be formed post injection such as by grinding, cutting, hot stamping (melting), solvent melting, etc. However, forming recesses 12a and 12b during the shoe molding process provides the greatest level of accuracy for recess formation as well as production throughput. In the illustrated embodiments, the depth of either recess 12a or 12b is preferably about 4mm. Referring more specifically to Figs. 2 and 3, tread inserts 50a and 50b will now be described. Each tread insert 50a or 50b comprises inner surface 52, which contacts outer sole 24 when installed in a recess 12a or 12b, outer surface 54, which may include siping or other tread features/patterns 56, and peripheral surface 58. Tread inserts are preferably constructed from an injection molding process using natural or synthetic rubber, and adhered by way of solvent and/or adhesive to shoe 10, although as noted elsewhere herein, other fastening means may be used without departing from the scope and spirit of the invention. The tread inserts may be color coordinated with the shoe, or may contrast with the shoe and/or each other (if two or more). Additionally, any tread insert may comprise multiple colors or be of heterogeneous composition.

Tread insert(s) 50a and/or 50b preferably have a sectional thickness equal to the sectional depth of respective recess(es) 12a and/or 12b, although function, design and/or aesthetic considerations may dictate a thicker or thinner tread insert. In addition, the sectional thickness of a tread insert need not be constant; traction features, orthopedic derived features, protrusions, recesses, undulations, waves, raised patterns and similar treatments can be incorporated into the tread

insert and vary, to varying degrees, the performance and aesthetics of the shoe. Thus, it is possible to have a single shoe design be adapted, via different tread inserts, into a beach shoe or a mud shoe.

From the foregoing, it should also be apparent that the number and geometric form of the shoe recesses are within the discretion of the skilled practitioner. Recesses forming various patterns, either fanciful or functional, can be filled with various inserts that individually and/or collectively occupy the recesses. Moreover, the location of the recesses is not constrained to outer surface 24 of sole 20. Because of the homogeneous nature of shoe 10, recesses 12 can be formed in sidewall 40, and particularly in toe portion 42 and heel portion 46 to reduce the effects of toe and heel scuffing. In addition, and as described previously, the formed recesses may extend beyond the perimeter of outer surface 24 such that peripheral surface 58 of a tread insert 50 may be exposed. This design may be of particular use when alerting a prospective purchaser to any "internal" features of the insert, particularly when orthopedic designs are employed.