Toe protectors

Details Toe protectors Toe protectors

1998-12-04

2003-07-29

Patterson, M. D. (Department: 3728)

Boots, shoes, and leggings

Toe caps and tips

C036S07700R

Reexamination Certificate

active

06598323

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The present invention relates to toe protectors and their composition and manufacturing process.
2. Background Art
Toe caps have served for foot protection in many different areas, from industry to sports to public safety. In the past, the field was dominated by metal or steel toe caps. This type of toe cap is illustrated by the following patents: U.S. Pat. No. 4,908,963, to Krajcir, et al, entitled “Safety Shoe”; U.S. Pat. No. 4,257,177, to Unsted, entitled “Safety Footwear”; U.S. Pat. No. 4,870,762, to Lee, entitled “Safety Shoe Structure”; U.S. Pat. No. 4,231,170, to Griswold, entitled “Instep Protector for Safety Shoes”; U.S. Pat. No. 4,575,953, to Hetzel, entitled “Safety Shoe with Toe Protecting Cap”; and U.S. Pat. No. 3,995,382, to Smith, entitled “Instep Guard for Safety Shoes.” While resistant to most forces, steel toe caps have the disadvantage of compressing under extreme pressure, and retaining the compressed shape after the force is removed. This can result in pinching or trapping the foot. In addition to the compression problem, steel toe caps have the added disadvantage of being thermally and electrically conductive, and respond to electromagnetic signals, making steel an unsuitable material for applications in certain fields such as the utility industries. These shortcomings led to the development of use of other, non-metallic compounds to make toe caps.
Numerous patents issued encompassing a variety of shapes and constructs of protective non-metallic footwear. These include U.S. Pat. No. 4,908,963, to Krajcir et al., (flexible metatarsal guard made of plastic, disposed above a steel toe); U.S. Pat. No. 5,074,060, to Brncick (molded semi-rigid plastic toe protector removably attached to shoe); U.S. Pat. No. 4,825,563, to Strongwater (wrap-around shoe attachment made of PVC, cloth, leather or vinyl); U.S. Pat. No. 4,231,170, to Griswold, (instep protector); U.S. Pat. No. 4,103,438, to Fron, (toe/instep protection made of thick polycarbonate in the shape of a clog); and U.S. Pat. No. 3,974,578, to Oettinger, et al, (elastomer cup on tip of tennis shoe).
The prior art does not provide the degree of protection required in many industrial settings. In order to reach full industrial applicability, toe protectors need to meet the minimum testing requirements set by the various safety associations (e.g., American national Standards Institute—ANSI; Occupational Safety and Health Administration—OSHA; Mine Safety and Health Administration—MSHA; and Canadian Standards Association). These tests include both compression and impact studies, and are very rigorous. The ANSI compression test consists of exerting 50 pounds per second (222.4 N) after a load of 500 pounds (2224 N) is reached. The tested specimens are ranked according to the level above this force the specimen can withstand. There are three levels of classifications based upon testing stringency: 1000 pounds, 1750 pounds, and 2500 pounds of compression. Likewise, the ANSI impact resistance test consists of measuring the distance at the moment of maximum deflection at varying forces. The clearance must be at least {fraction (16/32)} of an inch. If this clearance is maintained at deflection forces ranging form 30-75 foot-pounds, the protective footwear is said to pass. The three levels of classification for impact resistance are 30 foot-pounds, 50 foot-pounds, and 75 foot-pounds.
It has been a goal of the industry, therefore, to design a toe cap that would meet these strict safety requirements, yet still be comfortable, lightweight, and fit various shoe styles. As a result, those in the field turned to the use of polymeric compounds and other synthetics. Dykeman (U.S. Pat. No. 4,735,003) describes a toe protector made of plastic plus fibers of glass, carbon or Kevlar. Siskind (U.S. Pat. No. 4,862,606) describes a fiber-reinforced polymeric compound. The patents of Harwood (U.S. Pat. Nos. 5,210,963, and 5,331,751) disclose long synthetic fibers composed of materials such as polyurethane. Harwood (U.S. Pat. No. 5,809,666) describes a plastic toe cap of minimum thickness of 0.17 inches, and Harwood (U.S. Pat. No. 5,666,745) describes thickness at non-impact points. Several patents describe various constructs to attempt to distribute crushing impact force. These include longitudinal grooves to shift the fracture point (Dykeman), and horizontal slots in the front wall of substantially reduced cross-section for a controlled vertical collapse (Harwood). However, the toe protectors in the field use long fibers (Dykeman,—fiber length of ½ to 2 inches; Harwood,—fiber length of ¼ to one inch) in specific linear alignments. This structure requires a specific gating position and size during the manufacturing process.
The present invention utilizes short fibers or particles and a unique structure to eliminate the need for precise gating positioning, thus reducing the cost of manufacture. The short fibers also result in more consistency throughout the toe protector, and increase strength and flexibility while yielding a thinner, more comfortable device.
SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)
The present invention is directed to toe protectors, comprising short particles less than approximately 0.25 inches long and a binder. The particles are preferably non-metallic materials. In a preferred embodiment, the particles comprise fibers, and are preferably randomly arranged. In the preferred embodiment, the particles comprise graphite. In an alternative embodiment, the particles comprise glass. In yet another embodiment, the particles comprise polyparaphenylene terephthalamide. The particles may also comprise at least one of the following: polycarbonates, nylons, and ceramics.
In the preferred embodiment, the binder is a resin, such as polyurethane, polyvinylchloride, a mix of styrene, acrylonitrile and nitrile rubber, polycarbonates, nylon, polyethylene, polyethylene terephthalate, polypropylene, polyphenylene sulfide, polyetheretherketone, polyetheramide, polyamides, phenolics, polyesters, epoxies, polyacrylics, or light beam and electron beam curing materials.
The preferred particle content is between approximately 30% and 99% by weight. The preferred binder content is between approximately 1% and 70% by weight, and most preferably between approximately between 1% and 30% by weight. The invention may further comprise an impact modifier, preferably a composite rubber, and more preferably an ethylene propylene diene monomer.
The invention is also directed to toe protectors, comprising a top, a front end, and open back end and sides contiguous with the top and front, and a reinforcing matrix. The matrix preferably comprises ribs, which are horizontally and/or vertically arranged across the top and down the sides. The matrix may comprise zig-zag members. The matrix alternatively comprises at least one of the following configurations: ribs, striations, preferential thickening, and geometric shapes.
The thickness of the toe protector of the present invention is preferably less than approximately 0.165 inches at the matrix. The toe protector thickness at the non-matrix areas is preferably less than 0.135 inches.
The present invention additionally comprises a method of constructing toe protectors by providing a substance (preferably a non-metallic substance) comprising short particles less than 0.25 inches long in a composite material and a binder, and injecting the substance into a mold through a gate. In the preferred embodiment, injecting comprises injecting at a temperature between 300-600 degrees Fahrenheit and at a pressure between 10,000-25,000 psi. The gate may be a randomly-placed gate.
The toe protector of the present invention meets ANSI compression and impact resistance safety standards. A preferred embodiment of the toe protector meets ANSI compression standards of at least 1000 pounds, more preferably 1750 pounds, and most preferably 2500 pounds. A preferred embodiment of the present invention meets ANSI impact resistance stand

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