PUNCTURE RESISTANT FLEXIBLE METATARSAL GUARD
A metatarsal guard includes a base layer, an elastomeric polyurethane foam layer on the base layer, and a puncture resistant layer on the elastomer foam layer on a side opposite the base layer. Advantageously, the metatarsal guard is flexible and capable of providing top-of-foot protection to the metatarsal region of a foot. The metatarsal guard is formed by a molding process. A safety shoe or boot having improved protection for the metatarsal region of a wearer's foot is also disclosed.
The metatarsal region of the human foot extends forwardly from the front of the ankle to the base of the toes and contains a number of elongated bones extending side by side. The instep of the foot is particularly vulnerable to impact and crushing forces, especially those caused by falling or dropped objects. This region of the foot may also be injured if the metatarsal guard is allowed to move from its intended position.
Footwear manufacturers have manufactured steel-toed boots and shoes with a variety of metatarsal guards and cushions in an attempt to prevent the injuries described above. The most common method of protecting the metatarsal region is by placing a tough, rigid, synthetic plastic or metal shield over the exterior of the shoe to cover the metatarsal region of the foot. However, this method of protecting the metatarsal region creates an unsightly and clumsy appearance of the shoe. Furthermore, the rigid shield limits the range of motion of the foot during walking or running. The external metatarsal shield also pinches the instep when bending or squatting and can create a snagging and tripping hazard which could cause serious injury.
Others have incorporated the rigid synthetic plastic or metal metatarsal shield into a fabric or leather cover usually matching the material from which the footwear is made. This covered shield is then attached to the toe of the boot. In effect, the metatarsal shield becomes a second tongue placed over the exterior of the safety boot. This external shield does not solve the problems mentioned above which are associated with the uncovered, external metatarsal protectors. The shoes remain bulky and clumsy in appearance. Furthermore, the metatarsal protectors continue to be rigid, which prevents a full range of foot motion and results in fewer individuals wearing such protective equipment.
Accordingly, there remains a need in the art for an improved metatarsal guard. It would be especially advantageous to provide a metatarsal guard that is flexible, impact-absorbing, and puncture-resistant, and can easily be incorporated to an inner portion of a safety shoe or boot.
SUMMARYA metatarsal guard comprises: a base layer; an elastomeric polyurethane foam layer on the base layer; and a puncture resistant layer on the elastomer foam layer on a side opposite the base layer; wherein the metatarsal guard is flexible.
A method for the manufacture of a metatarsal guard comprises: arranging in a mold the base layer; the elastomeric polyurethane foam layer on the base layer; and the puncture resistant layer on the elastomer foam layer on a side opposite the base layer; and applying heat and pressure to the mold to provide the metatarsal guard.
A safety shoe or boot having improved protection for the metatarsal region of a wearer's foot represents another aspect of the present disclosure, the safety shoe or boot comprising the metatarsal guard.
The above described and other features are exemplified by the following FIGURE and detailed description.
The following FIGURES are exemplary embodiments wherein the like elements are numbered alike.
The present inventor has unexpectedly discovered that an improved metatarsal guard can be provided using a particular combination of materials to prepare a molded or shaped product which is well suited for incorporation into a safety shoe or boot and can provide improved protection to the metatarsal region of the foot. Advantageously, the metatarsal guard according to the present disclosure is flexible and conformable to the foot of wearer, and therefore comfortable to the wearer. This is in contrast previous metatarsal guards which have been constructed from rigid plastic or metal materials which can limit range of motion and be uncomfortable. Thus, a significant improvement is provided by the present disclosure.
Accordingly, an aspect of the present disclosure is a metatarsal guard. The metatarsal guard comprises a base layer, an elastomeric polyurethane foam layer on the base layer; and a puncture resistant layer on the elastomeric foam layer, on a side opposite the base layer. The materials for each of the respective layers are carefully selected such that the resulting metatarsal guard provides a desirable combination of flexibility, puncture-resistance, and impact absorption.
The metatarsal guard disclosed herein is a molded or shaped product and can therefore be provided by a method comprising arranging in a mold the base layer, the elastomeric polyurethane foam layer on the base layer, and the puncture resistant layer on the elastomer foam layer on a side opposite the base layer. Once arranged in the mold, the method further comprises applying heat and pressure to the mold to provide the metatarsal guard.
The base layer can comprise a thermoplastic polymer material. The base layer can assist with release from the mold after forming the metatarsal guard. In an aspect, the base layer can comprise a thermoplastic polyurethane. The thermoplastic polyurethane can be in the form of a film, for example, coated from a solvent-borne polyurethane thermoplastic composition. Thermoplastic polyurethane film can be desirable due to its combination of durability, elasticity, softness and flexibility.
An elastomeric polyurethane foam layer is on the base layer. Preferably the elastomeric polyurethane foam layer is directly on the base layer (i.e., no intervening layers are present). As used herein, “foam(s)” refers to a polymeric material having a cellular structure, where the cells can be open (reticulated) or closed. The properties of the foam (e.g., density, modulus, compression load deflection, tensile strength, tear strength, and so forth) can be adjusted by varying the components of the reactive compositions as is known in the art.
Polyurethane foam compositions, for use in making the elastomeric polyurethane foam layer of the metatarsal guard, are known in the art, being described, for example, in U.S. Pat. No. 6,915,741 to Price et al. In general, polyurethane foams are formed from compositions comprising an organic isocyanate component reactive with an active hydrogen-containing component, a surfactant, and a catalyst. One process for forming the foam comprises forming the above-described composition; substantially uniformly dispersing inert gas throughout the mixture by mechanical beating of the mixture to form a heat curable froth which is substantially structurally and chemically stable, but workable at ambient conditions; and curing the froth to form cured foam. Alternatively, the foam may be formed by addition of chemical or physical blowing agents known in the art, such as water, organic compounds when decomposed to generate gas, or volatile organic materials such as hydrocarbons. In an aspect, the chemical blowing agent is not halogenated (e.g., not chlorinated or fluorinated).
More specifically, the elastomeric polyurethane foam layer can be prepared by a reaction between at least one kind of diisocyanate, for example, selected from the group consisting of methylene diphenyl isocyanate (MDI), toluene diisocyanate (TDI), methylene diphenyl isocyanate (MDI) oligomer, toluene diisocyanate (TDI) oligomer, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IDPI), hydrogenated MDI (HMDI), and carbodiimide modified methylene diisocyanate; and at least one polyol mixture, for example, selected from the group consisting of polypropylene glycol, polytetramethylene glycol, and polyethylene glycol.
A cross-linking agent optionally can be used to increase cross-linking between an isocyanate pre-polymer and polyol in the polymerization reaction. Specifically, the cross-linking agent can be at least one agent selected from the group consisting of trimethylolpropane, triethanolamine, pentaerythritol, toluene diamine, ethylene diamine, glycerine, oxypropylated ethylene diamine, hexamethylene diamine, m-phenylene diamine, dimethanolamine, triethanolamine, and the like.
The polyurethane foams can be characterized by one or more of the following mechanical or physical properties. In particular, the elastomeric polyurethane foam layer can be open cell compressible foam having a specific gravity or density up to 1 g/cm3, specifically 0.08 to 0.8 g/cm3. In an aspect, the elastomeric polyurethane foam layer can have a 25% compressive strength (compression force deflection) of up to 10.0 kgf/cm2 (980.67 kPa), specifically from 0.01 to 5.0 kgf/cm2 (0.98 to 490.33 kPa). The tensile strength of the polyurethane foam can be 10 to 300 kgf/cm2, specifically 20 to 200 kgf/cm2, more specifically 50 to 150 kgf/cm2 and the elongation at break of the polyurethane foam can be 100 to 600%, specifically 300 to 500% in accordance with ASTM D3574.
In an aspect, the elastomeric polyurethane foam layer is prepared by a reaction of at least one kind of diisocyanate selected from the group consisting of methylene diphenylisocyanate (MDI), toluene diisocyanate (TDI), methylene diphenylisocyanate (MDI) oligomer, toluene diisocyanate (TDI) oligomer, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), hydrogenated MDI (HMDI) and carbodiimide modified methylene diisocyanate; and at least one polyol mixture selected from the group consisting of polypropylene glycol, polytetramethylene glycol, and polyethylene glycol.
In an aspect, the elastomeric polyurethane foam layer is a polyurethane foam, which can exhibit a desirable combination of compression force, deflection, compression set, as well as their good wear properties, e.g., conformability of the foot of a wearer. The polyurethane foam can have an average cell size of 50 to 250 micrometers (μm) (as can be measured in accordance with ASTM D 3574-95); a density of between about 5 to 30 pcf (0.08 to 0.48 g/cm3), specifically, 6 to 25 pcf (0.096 to 0.4 g/cm3); a compression set at 70° F. (21 degrees Celsius (° C.)) of less than about 10% as determined in accordance with ASTM-D 3574 Test D; and a 25% compression force deflection of 1 to 9 psi (7 to 63 kPa) as determined by ASTM-D 3574: PTP-0033 at 25% deflection. The foam can have a void volume content of 20 to 99%, specifically, 30 to 80%, based upon the total volume of the polymeric foam. In an aspect is an open cell foam. Such materials are marketed, for example, under the trade name PORON by the Rogers Corporation, Woodstock, Conn. PORON foams have been formulated to provide an excellent range of properties, including excellent compression set resistance. Foams with such compression set resistance can provide cushioning and maintain their original shape or thickness under loads for extended periods of time. The foam can comprise a PORON XRD™ high impact foam. The foam can comprise a PORON CFD™ high impact foam.
The elastomeric polyurethane foam can be filled or unfilled. Preferably, the elastomeric polyurethane foam is unfilled.
The elastomeric polyurethane foam layer can have a thickness of 0.1 to 10 millimeters (mm), specifically, 0.3 to 5 mm.
The foam is manufactured from a precursor composition that is mixed prior to or concomitant with foaming. Preferably, the elastomeric polyurethane foam layer can be formed by disposing a curable composition on the base layer in the mold. For example, the curable composition, comprising a mixture of polyol and isocyanate components and, optionally, one or more of a surfactant, a catalyst, and a blowing agent, is deposited onto the base layer in the open mold. The curable composition can form a cured, foamed layer (i.e., the elastomeric polyurethane foam layer) in situ during the molding process (i.e., between the base layer and the puncture resistant layer). In an aspect, the cured, foamed layer can infiltrate, at least partially, the puncture resistant layer disposed on the curable composition when cured in the mold. For example, the curable composition (and as a result the cured, foamed layer) can infiltrate the puncture resistant layer such that at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95% of the thickness of the puncture resistant layer comprises cured, foamed material in the molded product. In an aspect, the puncture resistant layer can comprise a gradient concentration of the curable composition, such that a higher content of the curable composition is present at the outer surface of the puncture resistant layer relative to the content of the curable composition at an inner portion of the puncture resistant layer. In an aspect, the puncture resistant layer can be completely impregnated with the curable composition (i.e., the curable composition can infiltrate the full thickness of the puncture resistant layer. In an aspect, the curable composition does not substantially penetrate the puncture resistant layer.
Alternatively, in some aspects, a preformed elastomeric polyurethane foam layer may be laminated to the base layer.
The puncture resistant layer is disposed on the elastomeric polyurethane foam layer, on a side opposite the base layer. Existing puncture resistant materials are typically very stiff and may severely hinder the comfort and tactile sensitivity of the wearer. Solid puncture resistant materials, such as polyethylene or leather, do not have the tip-puncture problem associated with textiles, but may be unacceptably stiff and therefore lead to severe reductions in dexterity and tactile sensitivity. The puncture resistant layer according to the present disclosure can comprise woven, high-strength fibrous materials. Exemplary woven, high-strength fibrous materials can comprise a woven polyester fabric (e.g., comprises polyester fibers) or a woven polyamide fabric (e.g., comprising polyamide fibers, for example poly aramid fibers, more specifically comprising poly(paraphenylene terephthalamide fibers). In an aspect, the puncture resistant layer can comprise a woven, high-strength fibrous material comprising a mixture of fibers, for example a mixture of polyester and polyamide fibers. In a specific aspect, a woven, high-strength fibrous material can comprise a woven polyamide outer layer and a woven polyester interior.
The woven materials of the present disclosure can overcome the technical limitations of the aforementioned stiff materials typically used to impart puncture resistance. The present inventor has further unexpectedly discovered that woven, high-strength fibrous materials can be incorporated into a molded or shaped product including an elastomeric polyurethane foam layer to provide a flexible metatarsal guard that also provides puncture resistance. Neither the combination of the woven, high-strength fibrous materials and elastomeric polyurethane foam layer nor molding of the combination adversely affected puncture resistance of the woven, high-strength fibrous materials.
In an aspect, the puncture resistant layer comprises the woven polyester fabric. The woven polyester fabric can have, for example, a weight of 700 to 900 g/m2, or 725 to 850 g/m2, or 750 to 800 g/m2. The woven polyester fabric can have, for example, a thickness of 0.1 to 2 millimeters, or 0.2 to 1 millimeter, or 0.2 to 0.5 millimeters, or 0.5 to 1.5 mm, or 0.75 to 1.25 mm. The woven polyester fabric can exhibit at least a level 2 puncture resistance, or at least a level 3 puncture resistance, according to EN388:6.5-16.
In an aspect, the polyester fabric layer can comprise more than one polyester fabric layer, each layer bonded to an adjacent layer with a suitable adhesive, for example a polyurethane or an epoxy, preferably a polyurethane. The stack of layers, alternating with the adhesive coating can be laminated together to provide the puncture resistant material. Without wishing to be bound by theory it is believed that the coating formed from the adhesive on the woven polyester fabric layer can further enhance the toughness of the puncture resistant material. When present, the coating or adhesive component of the puncture resistant layer can be present in an amount of 1 to 5 weight percent based on the total weight of the woven polyester fabric.
Mixed knit woven fabrics are also contemplated. For example, in an aspect the puncture resistant layer can comprise a mixed knit woven fabric comprising polyester and polyamide fibers.
An exemplary material suitable for use as the puncture resistant layer includes those available from Nam Liong Global Corporation, for example under the tradename TT-2801BT or CK-1080.
The molded metatarsal guard according to the present disclosure can have a total thickness of 1 to 20 millimeters (mm). Within this range, the molded metatarsal guard can have a total thickness of 2 to 18 mm, or 3 to 15 mm, or 5 to 13 mm. In a specific aspect, the molded metatarsal guard can have a total thickness of 5 to 7 mm. In another specific aspect, the molded metatarsal guard can have a total thickness of 11 to 14 mm.
The molded metatarsal guard described herein is advantageously flexible, in contrast with the rigid materials previously used for this application. In a further advantageous feature, in addition to the flexibility and impact absorption of the metatarsal guard, the inclusion of the particular puncture resistant layers can further provide improved puncture resistance, thereby enhancing top-of-foot protection for a wearer of a shoe which includes the metatarsal guard, which is shaped to conform to the top of the foot. For example, a force required for a dart having a tip diameter of 1 millimeter moving at a speed of 100 mm/min to puncture the metatarsal guard can be 100 Newtons or greater, for example 150 Newtons or greater, for example 175 Newtons or greater, for example 250 Newtons or greater. For example, a puncture force can be 100 to 600 Newtons, or 150 to 500 Newtons, or 250 to 500 Newtons. In an aspect, a force required for a dart having a tip diameter of 1 millimeter moving at a speed of 100 mm/min to puncture the metatarsal guard can be at least 100% greater, or at least 150% greater, or at least 200% greater, or at least 250% greater, or at least 300% greater, or at least 400% greater than a force required to puncture a comparative metatarsal guard not including the puncture resistant layer under the same conditions.
The molded metatarsal guards described herein can be particularly well suited for providing protection to the metatarsal region of a wearer's foot, particularly by incorporating the metatarsal guard into a safety shoe or boot. Accordingly, a method for providing top-of-foot protection to the metatarsal region of a foot represents another aspect of the present disclosure. The method comprises affixing a metatarsal guard inside an upper portion of a safety shoe or boot, wherein the metatarsal guard is according to the present disclosure and shaped to conform to the top of the foot.
A safety boot or shoe comprising the metatarsal guard represents another aspect of the present disclosure. For example, a safety shoe or boot comprising the metatarsal guard can comprise a sole; an upper portion having an interior surface, the upper portion being affixed to the sole wherein the upper portion and the sole define a cavity for receiving a wearer's foot; a rigid toe protector affixed between the upper portion and the sole; and the metatarsal guard positioned inside the upper portion and adjacent to the rigid toe protector to cover a top side of the metatarsal region of the wearer's foot. The metatarsal guard can be adhesively affixed to the interior prior of the upper portion of the safety shoe or boot. An exemplary safety shoe or boot including the metatarsal guard according to the present disclosure is depicted in
Accordingly, a significant advantage is provided by the present disclosure. The present inventor has unexpectedly discovered that the particular components described herein can be used in a molding process to provide an improved puncture-resistant, flexible metatarsal guard.
This disclosure is further illustrated by the following examples, which are non-limiting.
ExamplesTable 1 described the materials used in the following Examples.
The materials of Table 1 were used to prepare a puncture resistant composite comprising a layer of either Mixed Knit or the PE/PU disposed on a polyurethane foam layer. A fabric layer disposed on the foam layer, opposite the materials of Table 1.
The metatarsal guards were molded by placing a thermoplastic polyurethane layer (TPU) film in the open mold. A polyurethane foam precursor mixture comprising polyurethane foam raw materials (e.g., polyol, isocyanate, crosslinker, blowing agent) was poured on top of the TPU layer. The puncture resistant fabric (Mixed Knit or PE/PU) was placed on top of the foam precursor. The mold was closed, and vacuum applied. A molding temperature of 200 to 210° F. (93.3 to 98.9° C.) was used to cure the materials and provide the metatarsal guards.
The molded metatarsal guards were evaluated for puncture resistance. It is noted that presently, there is no industry accepted standard for characterizing puncture resistance for top-of-foot puncture resistance. The method used to evaluate the materials described in the present examples was based on a modified version of the ANSI: EN388 test method. Samples were tested using a speed of 100 mm/min using a dart having a tip diameter of approximately 1 mm. The force required to puncture the material was recorded in Newtons. Results are summarized in Table 2.
As shown in Table 2, the woven PE/PU and Mixed Knit materials provided improved puncture resistance compared to a metatarsal guard not including any puncture resistant layer at all (i.e., Example 1). The PE/PU puncture resistant layer provided the highest puncture force. A significant improvement is therefore provided by the present disclosure.
This disclosure further encompasses the following aspects.
Aspect 1: A metatarsal guard comprising: a base layer; an elastomeric polyurethane foam layer on the base layer; and a puncture resistant layer on the elastomer foam layer on a side opposite the base layer; wherein the metatarsal guard is flexible.
Aspect 2: The metatarsal guard of aspect 1, wherein the base layer comprises a thermoplastic polyurethane.
Aspect 3: The metatarsal guard of aspect 1 or 2, wherein the elastomeric polyurethane foam layer is an open cell polyurethane foam.
Aspect 4: The metatarsal guard of any of aspects 1 to 3, wherein the elastomeric polyurethane foam has an average cell size of 50 to 250 micrometers.
Aspect 5: The metatarsal guard of any of aspects 1 to 4, wherein the elastomeric polyurethane foam has a density of 5 to 30 pcf, specifically, 6 to 25 pcf.
Aspect 6: The metatarsal guard of any of aspects 1 to 5, wherein the elastomeric polyurethane foam has a compression set at 70° F. of less than 10% as determined in accordance with ASTM-D 3574 Test D.
Aspect 7: The metatarsal guard of any of aspects 1 to 6, wherein the elastomeric polyurethane foam has a 25% compression force deflection of 1 to 9 psi as determined by ASTM-D 3574: PTP-0033 at 25% deflection.
Aspect 8: The metatarsal guard of any of aspects 1 to 7, wherein the elastomeric polyurethane foam is unfilled.
Aspect 9: The metatarsal guard of any of aspects 1 to 8, wherein the puncture resistant layer comprises a woven polyester fabric or a woven polyamide fabric.
Aspect 10: The metatarsal guard of any of aspects 1 to 9, wherein the puncture resistant layer comprises a woven polyester fabric.
Aspect 11: The metatarsal guard of aspect 10, wherein the woven polyester fabric has a weight of 750 to 800 g/m2.
Aspect 12: The metatarsal guard of any of aspects 1 to 11, wherein the puncture resistant layer has a thickness of 0.5 to 1.5 millimeters.
Aspect 13: The metatarsal guard of any of aspects 1 to 11, wherein the puncture resistant layer comprises a woven polyester fabric having a weight of 750 to 800 g/m2; a thickness of 0.65 to 1.25 millimeters; and a level 3 puncture resistance according to EN388:6.5-16.
Aspect 14: The metatarsal guard of any of aspects 1 to 13, wherein the metatarsal guard has a thickness of 1 to 20 mm, or 2 to 18 mm, or 3 to 15 mm, or 5 to 13 mm, or 5 to 7 mm, or 11 to 14 mm.
Aspect 15: The metatarsal guard of any of aspects 1 to 14, wherein the metatarsal guard is formed by a method comprising: arranging in a mold the base layer; the elastomeric polyurethane foam layer on the base layer; and the puncture resistant layer on the elastomer foam layer on a side opposite the base layer; and applying heat and pressure to the mold to provide the metatarsal guard.
Aspect 16: A method for the manufacture of a metatarsal guard of any of aspects 1 to 15, the method comprising: arranging in a mold the base layer; the elastomeric polyurethane foam layer on the base layer; and the puncture resistant layer on the elastomer foam layer on a side opposite the base layer; and applying heat and pressure to the mold to provide the metatarsal guard.
Aspect 17: A safety shoe or boot having improved protection for the metatarsal region of a wearer's foot, the safety shoe or boot comprising the metatarsal guard of any of aspects 1 to 15.
Aspect 18: The safety shoe or boot of aspect 17, comprising: a sole; an upper portion having an interior surface, the upper portion being affixed to the sole wherein the upper portion and the sole define a cavity for receiving a wearer's foot; a rigid toe protector affixed between the upper portion and the sole; and the metatarsal guard positioned inside the upper portion and adjacent to the rigid toe protector to cover a top side of the metatarsal region of the wearer's foot.
Aspect 19: The safety shoe or boot of aspect 18, wherein the metatarsal guard is adhesively affixed to the interior of the upper portion.
Aspect 20: A method for providing top-of-foot protection to the metatarsal region of a foot, the method comprising: affixing a metatarsal guard inside an upper portion of a safety shoe or boot, the metatarsal guard comprising: a base layer; an elastomeric polyurethane foam layer on the base layer; and a puncture resistant layer on the elastomer foam layer on a side opposite the base layer; wherein the metatarsal guard is flexible.
The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.
All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “first,” “second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “a” and “an” and “the” do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and/or” unless clearly stated otherwise. Reference throughout the specification to “an aspect” means that a particular element described in connection with the aspect is included in at least one aspect described herein, and may or may not be present in other aspects. The term “combination thereof” as used herein includes one or more of the listed elements, and is open, allowing the presence of one or more like elements not named. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various aspects.
It will be understood that when an element is referred to as being “on” another element or “in contact” with another element, it can be directly on the other element or intervening elements may be present therebetween, unless explicitly stated otherwise. In contrast, when an element is referred to as being “directly on” or “directly in contact with” another element, there are no intervening elements present.
Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.
Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.
Compounds are described using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash (“-”) that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example,-CHO is attached through carbon of the carbonyl group.
While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.
Claims
1. A metatarsal guard comprising:
- a base layer;
- an elastomeric polyurethane foam layer on the base layer; and
- a puncture resistant layer on the elastomer foam layer on a side opposite the base layer;
- wherein the metatarsal guard is flexible.
2. The metatarsal guard of claim 1, wherein the base layer comprises a thermoplastic polyurethane.
3. The metatarsal guard of claim 1, wherein the elastomeric polyurethane foam layer is an open cell polyurethane foam.
4. The metatarsal guard of claim 1, wherein the elastomeric polyurethane foam has an average cell size of 50 to 250 micrometers.
5. The metatarsal guard of claim 1, wherein the elastomeric polyurethane foam has a density of 5 to 30 pcf (0.08 to 0.48 g/cm3).
6. The metatarsal guard of claim 1, wherein the elastomeric polyurethane foam has a compression set at 70° F. of less than 10% as determined in accordance with ASTM-D 3574 Test D and a 25% compression force deflection of 1 to 9 psi as determined by ASTM-D 3574: PTP-0033 at 25% deflection.
7. The metatarsal guard of claim 1, wherein the elastomeric polyurethane foam is unfilled.
8. The metatarsal guard of claim 1, wherein the puncture resistant layer comprises a woven polyester fabric or a woven polyamide fabric.
9. The metatarsal guard of claim 1, wherein the puncture resistant layer comprises a woven polyester fabric.
10. The metatarsal guard of claim 10, wherein the woven polyester fabric has a weight of 750 to 800 g/m2.
11. The metatarsal guard of claim 1, wherein the puncture resistant layer has a thickness of 0.1 to 2 millimeters.
12. The metatarsal guard of claim 1, wherein the puncture resistant layer comprises a woven polyester fabric having
- a weight of 750 to 800 g/m2;
- a thickness of 0.65 to 1.25 millimeters; and
- a level 3 puncture resistance according to EN388:6.5-16.
13. The metatarsal guard of claim 1, wherein the metatarsal guard has a thickness of 1 to 20 millimeters (mm).
14. The metatarsal guard of claim 1, wherein the metatarsal guard is formed by a method comprising:
- arranging in a mold the base layer; the elastomeric polyurethane foam layer on the base layer; and the puncture resistant layer on the elastomer foam layer on a side opposite the base layer; and
- applying heat and pressure to the mold to provide the metatarsal guard.
15. The metatarsal guard of claim 1, comprising:
- the base layer, comprising a thermoplastic polyurethane;
- the elastomeric polyurethane foam layer, wherein the elastomeric polyurethane foam layer is an open cell polyurethane foam, the elastomeric polyurethane foam has an average cell size of 50 to 250 micrometers, and the elastomeric polyurethane foam has a density of 5 to 30 pcf.; and
- the puncture resistant layer, comprising a woven polyester fabric having a weight of 750 to 800 g/m2, a thickness of 0.65 to 1.25 millimeters, and a level 3 puncture resistance according to EN388:6.5-16;
- wherein the metatarsal guard is flexible; and
- wherein the metatarsal guard has a total thickness of 5 to 7 millimeters or 11 to 14 mm.
16. The metatarsal guard of claim 1, wherein a force required for a dart having a tip diameter of 1 millimeter moving at a speed of 100 mm/min to puncture the metatarsal guard is at least 100% greater than a force required to puncture a comparative metatarsal guard not including the puncture resistant layer.
17. A method for the manufacture of a metatarsal guard of claim 1, the method comprising:
- arranging in a mold the base layer; the elastomeric polyurethane foam layer on the base layer; and the puncture resistant layer on the elastomer foam layer on a side opposite the base layer; and
- applying heat and pressure to the mold to provide the metatarsal guard.
18. A safety shoe or boot having improved protection for the metatarsal region of a wearer's foot, the safety shoe or boot comprising the metatarsal guard of claim 1.
19. The safety shoe or boot of claim 18, comprising:
- a sole;
- an upper portion having an interior surface, the upper portion being affixed to the sole wherein the upper portion and the sole define a cavity for receiving a wearer's foot;
- a rigid toe protector affixed between the upper portion and the sole; and
- the metatarsal guard positioned inside the upper portion and adjacent to the rigid toe protector to cover a top side of the metatarsal region of the wearer's foot.
20. A method for providing top-of-foot protection to the metatarsal region of a foot, the method comprising:
- affixing a metatarsal guard inside an upper portion of a safety shoe or boot, the metatarsal guard comprising:
- a base layer;
- an elastomeric polyurethane foam layer on the base layer; and
- a puncture resistant layer on the elastomer foam layer on a side opposite the base layer;
- wherein the metatarsal guard is flexible.
Type: Application
Filed: Mar 31, 2023
Publication Date: Oct 3, 2024
Inventor: Loni Decelles (Brooklyn, CT)
Application Number: 18/129,774
