DETAILED DESCRIPTION

[0020] The present invention provides a sandal with high traction material on the supper surface of the sandal sole. The traction material comprises granules of hard material such as crushed rock, ceramic or hard polymers (e.g. phenolic). The traction material can be distributed over the entire sandal, or can be located only in weight-bearing areas of the sandal (e.g. under the foot ball, toes and heel). The traction material can be absent from the instep area (central portion) of the sandal. The granules can be incorporated (embedded) into the material of the sandal sole (e.g. incorporated into a foam rubber sandal sole), or can be adhered to the sandal sole with an adhesive (e.g. urethane, rubber or epoxy), or can be adhered to a patch (e.g. fabric or plastic) that is bonded (may be removable or nonremovable) to the sandal sole. The traction surface grips the foot, even when wet. In this way, slipping is prevented, and damage to the sandal and personal injuries are avoided.

[0021] FIG. 1 shows a flip-flop sandal according to the present invention. The sandal has a sole 20 with straps 22. The straps 22 hold the sandal on a wearers foot. The sandal includes granules 24 disposed over the surface of the sandal sole 20. The granules are hard and small (preferably smaller than 3 mm diameter or so) and provide a high traction surface that does not become slippery when wet.

[0022] The granules 24 can be made of many different materials including crushed rock, silicates, limestone, pumice, phenolics or other materials. The granules should be made of a material that is harder than the sole. For example, the granules can be made of relatively hard rubber particles. In this case, the granules should have a relatively high coefficient of friction when wet. The granules can have a wide size range, for example in the range of about 50-2000 microns.

[0023] The granules are preferably adhered to the sole 20 with an adhesive such as urethane, epoxy or the like. Rubber or latex adhesives can also be used. The adhesive can be solvent based or a curable adhesive or any other asdhesive. The granules can be mixed in the adhesive to form a slurry before being applied to the sandal. Alternatively, the sandal is coated with adhesive material, and then the granules are sprinkled onto the coated sandal.

[0024] FIG. 2 shows an alternative embodiment of the invention in which the granules are present only in a heel portion 26 and a front portion 28. The front portion 28 is in contact with the ball of the foot and toes when the sandal is worn. A central portion 30 (under the foot arch) is not coated with granules. The central portion 30 is generally not weight bearing. Absence of granules in the central portion 30 is preferred because granules can tend to irritate the arch of the foot, which does not have thick, tough skin.

[0025] FIG. 3 shows another embodiment in which the granules 24 are only provided on a portion of the sole aligned with the ball of the foot. In many cases, providing granules only in the region of the foot ball will provide adequate traction between the foot and sandal.

[0026] FIG. 4 shows a cross-sectional view of the present sandal. The granules 24 are adhered to the sole 20 with an adhesive 32. The granules 24 project from the adhesive to provide a high traction surface. The adhesive may be applied as a thin layer.

[0027] FIGS. 5a and 5b show embodiments in which the granules 24 are incorporated into the material of the sole 20. Sandal soles 20 are typically made of foam rubber or similar materials and are typically made by molding. In the embodiment of FIG. 5a, the granules 24 are embedded in an upper layer 25 of the sole. The upper layer 25 containing granules is bonded (e.g. by adhesive) to a lower layer 27 that does not contain granules 24. The top layer 25 may be 1-5 millimeters thick, for example. In FIG. 5b the sole has granules embedded throughout its entire volume.

[0028] FIG. 6 shows an embodiment where patches 34 on the sandal contain the granules 24.

[0029] In a preferred embodiment, the patches 34 are recessed in the sole. FIG. 7 shows a cross-sectional view. The top surface of the patches may be raised slightly above the top surface of the sole 20. This will provide better contact between the foot and the granules 24.

[0030] FIG. 8 illustrates a method for making a sandal with patches 34. In this method, the sandal sole 20 has recesses 36 for receiving the patches 34. The patches 34 in this case are pre-molded discs or plugs with embedded granules 24. The patches 34 are sized to fit within the recesses and are glued into the recesses. The patches 34 may be molded from urethanes, rubber or other polymers. Preferably, the patches 34 are made from a material that is harder than the sandal sole.

[0031] FIG. 9 shows another aspect of the invention, the sandal includes a length of webbing 38 or strip of fabric with granules 24 bonded thereon. The strip 38 may be permanently bonded to the sandal, or may be removable, for example by hook-and-loop fasteners. In this way, the granules 24 can be removed from the sandal when they are not desired.

[0032] FIG. 10 shows another aspect of the invention in which cuts or trenches 40 divide the sandal sole 20 into separately flexible zones or columns 42. With the columns 42 separately flexible, the sandal sole 20 can conform to the foot, even if the granules 24 and associated adhesive create a relatively rigid surface.

[0033] Although the present invention has been illustrated with sandals having a flip-flop or ‘thong’ type strap, the present invention includes any open-toe sandal, including sandals having straps made of webbing. The present invention is particularly applicable to sandals designed for use in and around water.

[0034] It will be clear to one skilled in the art that the above embodiment may be altered in many ways without departing from the scope of the invention. Accordingly, the scope of the invention should be determined by the following claims and their legal equivalents.