Boots – shoes – and leggings – Insoles – Laminated
Utility Patent
1999-11-19
2001-01-02
Kavanaugh, Ted (Department: 3728)
Boots, shoes, and leggings
Insoles
Laminated
C036S073000, C036S03000A, C036S004000
Utility Patent
active
06167639
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to puncture resistant insoles for boots and other shoes.
Manufacturing, construction and demolition sites are often full of sharp objects such as protruding nails which present a significant hazard to unwary workers. When stepped on, upturned nails in a board or the like easily penetrate the worker's boot and foot causing considerable pain and injury. Such a puncture wound can hobble a worker for weeks and requires particular medical attention to avoid tetanus or other anaerobic bacterial infections.
The current OSHA puncture hazard requirement is being met by the incorporation of a steel or metal insole in worker footwear. The use of metal insoles presents several problems and has several undesirable characteristics. In particular, metal is, by its nature, relatively inflexible and stiff. The use of footwear which is inflexible or stiff causes workers to be unable to flex their feet when walking, climbing, or working on difficult, uneven surfaces. As a result, the wearer is subject to falling, stumbling, and slipping. In short, there is a substantial loss of sure-footedness when wearing the present puncture resistant footwear.
The metal in currently available puncture resistant footwear conducts both electricity and heat. Workers who wear footwear containing a steel insole are, thus, more subject to frostbite when working in cold environments. Further, footwear with metal insoles cannot be worn by electrical workers. Instead, a non-conducting fiberglass insole is required for those engaged in electrical work. Fiberglass manufacturing processes, however, are subject to numerous environmental issues, which tend to increase the cost of fiberglass. Moreover, the fiberglass insole must be quite thick to provide the required puncture resistance, which reduces both the comfort and flexibility of the shoe.
Insoles have been developed which comprise multiple layers of stacked fibrous materials or fabric which are bonded together by synthetic resins and the like to form resin impregnated laminates. Fibrous materials previously identified as useable include spun glass fibers or nylon. Impregnation of the fabric is indicated as necessary to provide the desired puncture resistance. However, the resin impregnation process adds to the cost of materials and labor, reduces flexibility of the resulting insole and generally adds to the overall thickness of the insole.
Any puncture resistant insole which appreciably decreases the flexibility of the footwear or which is too thick is uncomfortable for workers to wear, and workers will remove the puncture resistant footwear when supervisors or regulators are not present. In addition, many workers wear the safety shoes only when doing jobs requiring the safety shoes and then change to more comfortable shoes when they are not needed. A more comfortable shoe would make these changes unnecessary and, as a consequence, reduce worker downtime.
There remains a need for a way to increase the puncture resistance of boots and the like without sacrificing comfort and flexibility or significantly increasing the weight of the boot.
SUMMARY OF THE INVENTION
The present invention comprises an improved sole or insole for a shoe including multiple layers of a tightly woven fabric formed from high tensile strength synthetic or polymeric fibers. Preferred fibers include polyaramid fibers, such as Kevlar® or Twaron® fibers of 200 denier fineness in a 70—70 weave. Kevlar is a registered trademark of E. I. du Pont de Nemours & Co. and Twaron is a registered trademark of Akzo Nobel Fibers B.V. It is foreseen that other high tensile strength synthetic fibers, such as Spectra®, a high molecular weight polyethylene, could be utilized. In one embodiment, an insole is utilized as a liner for insertion into an existing boot or other type of shoe to provide puncture resistance. In another embodiment, the layers of puncture resistant material are secured between an inner and outer layer of the sole of the shoe. The layers of puncture resistant fabric may be secured together along the outer peripheries thereof, or they may be secured within a pocket formed from a covering material, such as foam, leather, cotton or other fabrics. The layers of puncture resistant fabric may also be secured within a pocket formed between an inner and outer sole of the boot or shoe. The layers may also be secured within various enveloping materials or structures such as a shrink wrap plastic film. In the inventive insole, the fibers forming the layers of puncture resistant fabric are not impregnated by resins or adhesives since such impregnation is not required to provide structural support and to hold the fibers in place.
OBJECTS AND ADVANTAGES OF THE INVENTION
The objects of this invention include: to provide a boot or shoe which is puncture resistant; to provide a sole for boots or shoes which resists punctures; to provide such a sole which is relatively light weight; to provide such a sole without appreciably reducing shoe flexibility; to provide such a sole which is neither thermally or electrically conductive; to provide a puncture resistant insole for forming such a sole which is relatively thin; to provide such an insole which is relatively comfortable to use; to provide such an insole which may be purchased separately as an insert for an existing boot; to provide such an insole which does not slip when positioned within a boot; to provide such an insole which is relatively inexpensive to manufacture; and to provide such an insole which is particularly well adapted for its intended purposes thereof.
Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.
The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.
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Kavanaugh Ted
Shughart Thomson & Kilroy P.C.
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