WO2000064292A1

WO2000064292A1 - Protector for footwear

Info

Publication number: WO2000064292A1
Application number: PCT/AU2000/000378
Authority: WO
Inventors: Norman William Macleod
Original assignee: Normac Agencies Pty Ltd
Priority date: 1999-04-27
Filing date: 2000-04-27
Publication date: 2000-11-02
Also published as: DE10081296T1; AUPP997699A0

Abstract

The metatarsal protector (2) includes at least one element (11, 12) which is made of energy absorbing material, e.g. energy absorbing rubber or energy absorbing foam, having a high hysteresis loss and a low rebound. Ideally butyl and/or nitrile rubber is used. The at least one element has a grid like pattern of a plurality of linear or rib-like load absorbing formations (13) projecting outwardly proud of at least one of the surfaces thereof. The load absorbing formations are solid, i.e. in the sense that they do not contain bubbles or gas pockets. At least some of the load absorbing formations on one surface of an element are offset relative to the corresponding formations on the other surface of the element, to dissipate the energy from an object which has been dropped onto the protector away from a user's foot.

Description

PROTECTOR FOR FOOTWEAR

This invention relates to footwear. More specifically, this invention relates to a metatarsal protector for an item of footwear.

A metatarsal protector is applied to an upper or roof region of an item of footwear, e.g. a safety boot, and provides protection to the metatarsal region of a user's foot. Fig 1 shows the general orientation of a metatarsal protector in a conventional work boot.

A metatarsal protector is required to meet the European standard EN 344, part 2, and traditionally such metatarsal protectors have been made from metal or other rigid material such as fibreglass. The disadvantage of using such a rigid material is that a user, i.e. a wearer of a boot fitted with such a protector, is not easily able to bend their foot. More recently a metatarsal protector made from a resilient rubber has been produced, such a protector comprising two flattened elements superimposed on each other, with the upper element having a smaller surface area than the lower element. The elements, which are typically made of a resilient material such as rubber, include internal voids or bubbles filled with air which compress elastically when a falling object impacts the protector. While these rubber protectors perform some protective function, it would be advantageous to provide a protector having improved properties, or which at least provides consumers with a choice.

According to a first aspect of this invention, there is provided a metatarsal protector including at least one element which is made of energy absorbing material selected from the group of energy absorbing rubber, energy absorbing plastics, and energy absorbing foam.

An energy absorbing rubber is a rubber which has a high hysteresis loss and a low rebound. High hysteresis rubbers typically contain large amounts of fillers and oils. Particular suitable energy absorbing high hysteresis rubbers are butyl and nitrile rubbers although it must be appreciated that other rubbers may also be used. Known metatarsal protectors of resilient rubber possess high rebound characteristics, which can be somewhat inadequate in successfully dissipating the kinetic energy of a falling object.

Advantageously the protector comprises at least a first and a second said element of energy absorbing rubber superimposed one upon the other, each of said elements having a flattened configuration with two major surfaces.

Advantageously the first element has a relatively larger surface area and the second element a relatively smaller surface area.

At least one element, typically both said first and second elements, have a plurality of load absorbing formations projecting outwardly proud of at least one of the surfaces thereof. Preferably said first and second elements have load absorbing formations projecting outwardly proud of both surfaces.

Typically for an energy absorbing rubber element, the load absorbing formations are solid, i.e. in the sense that they do not contain bubbles or air pockets. Preferably said first and second elements are also solid and do not have any internal voids or air bubbles or gas pockets formed therein.

Preferably at least some of the load absorbing formations on one surface of an element are offset relative to the corresponding formations on the other surface of the element.

This feature of offset load absorbing formations on the upper and lower surfaces of an element has the effect of more effectively dissipating the energy from an object which has been dropped onto the protector away from a user's foot.

Preferably the load absorbing formations are of elongate substantially linear or rib-like configuration. Thus the rib-like formations on one surface of the element may be positioned in between the rib-like formations on the other surface. The invention, however, includes load absorbing formations having other configurations, for example they could be discrete formations having a frustoconical or other shape. In a particularly preferred embodiment of the invention, each surface of the element has a first set of rib-like formations extending in one direction and a second set of rib-like formations extending in another direction substantially perpendicular to said first direction, so that the rib-like formations form a grid pattern.

Advantageously there is at least one discrete space or interval across the length of at least one element which is free of load absorbing formations. Preferably there are a plurality of said spaces or intervals, e.g. three to four spaced along the length of the at least one element. These spaces between load absorbing formations ease flexing of the protector and the boot to which the protector is fitted making it more comfortable to wear and to walk in.

Typically the protector further includes a flexible pouch within which the at least one energy absorbing element is contained. Preferably the pouch is made of leather, i.e. synthetic or real.

Optionally the protector may include at least one further element such as a pad contained within the pouch, e.g., made of foam rubber, or foam polyurethane. Advantageously the protector contains two said further pad elements, i.e. on each side of the rubber elements, positioned between the rubber elements and the pouch. It is preferred that such a pad element not be positioned between the energy absorbing elements.

One function of the foam pad elements is to improve the aesthetics of the protector, i.e. to prevent the shape of the pad showing through the pouch. A second function is to enhance the comfort of the protector.

Optionally at least one of the rubber elements may include support means, e.g. elongate strips of metal. Typically the strips of metal would be disposed internally within the element. The strips enable the protector to be shaped so as to complement the shape of the foot of a wearer, e.g., giving the protector a curved shape in a longitudinal direction. Typically the strips would permit flexing in one direction but resist flexing in another direction. According to another aspect of this invention, there is provided an item of footwear including a metatarsal protector as described above with respect to the first aspect of the invention.

The protector of the item of footwear may include any one or more of the features described above with respect to the first aspect of the invention.

Preferably the item of footwear is a boot, e.g. a safety boot.

A metatarsal protector in accordance with this invention may come in a variety of forms. It will be convenient to hereinafter describe in detail one specific embodiment of the invention with reference to the accompanying drawings. It is to be clearly understood however that the specific nature of this description does not supersede the generality of the preceding broad description. In the drawings:

Fig. 1 is a three-dimensional view of a safety boot fitted with a metatarsal protector;

Fig. 2 is similar view showing more detail of the protector of the invention fitted to the boot of Fig. 1 ;

Fig. 3 is a top plan view of one element of the protector in Fig. 2; Fig. 4 is a bottom plan view of the element of Fig. 3; Fig. 5 is cross sectional view through the element of Fig. 3, section through V-V; Fig. 6 is a top plan view of the second element of the protector of Fig. 2;

Fig. 7 is a bottom plan view of the element of Fig. 6; Fig. 8 is an isometric view of a metatarsal protector in accordance with a further embodiment of the invention, attached to a metal toecap for a workboot; and Fig. 9 is a cross-sectional view through the vertical sagittal plane of the protector and toecap combination of Fig. 8.

Fig. 1 illustrates a safety boot 1 having a metatarsal protector 2 mounted thereon. Broadly speaking, the boot comprises a sole 3, an upper 4, a toe cap 5 and a heel 6. The protector 2 extends across the upper or metatarsal region of a wearer's foot which is indicated broadly by the numeral 7. The protector 2 is typically positioned on the boot 1 with straps 8 and is permanently attached to the boot 1 by rivets 9.

Fig. 2 illustrates the protector 2 according to the invention in more detail. The protector 2 comprises two superimposed resilient rubber elements 11 and 12 enclosed within a leather pouch 10 (shown in outline). As an alternative to the fixing of the protector as illustrated in Fig. 1 , the protector may be stitched to the upper 4. The upper element 11 is smaller than (being of shorter length but substantially the same width as) the element 12, and is superimposed upon element 12, positioned towards the toe cap end of the protector 2. The reason for superimposing the two elements 11 and 12 at the toe cap end is that this region is required to fulfil a greater load bearing function than the other end thereof.

The elements 11 and 12 are made by vulcanised moulding from an energy absorbing rubber with a low rebound or high hysteresis loss. Alternatively the elements 11 and 12 may be injection moulded. Compounds of butyl and nitrile rubbers are particularly suitable, for example SBR (styrene butadiene polymer), NBR (nitrile butadiene polymer) and BD (butadiene polymer). However it is to be understood that other rubbers having high hysteresis can also be used.

One NBR formulation which is particularly suitable is:

Component (parts by weight)

(approximate)

NBR 100

DOP 50

ISAF BLACK 50 (very fine carbon black)

ZINC OXIDE 5

STEARIC ACID 1

CBS 1

SULPHUR 2

A butyl rubber formulation which is particularly suitable is: Component (parts by weight)

(approximate)

POLYSAR Butyl 400 100

DIBENSO GMF 0.5

SAF Carbon Black 55

ZINC OXIDE 5

STEARIC ACID 0.5

KENFLEX A 5

IMPROVED SUNPROOF WAX 2

SULPHUR 1.5

TELLURAC 2

ALTAX 1

Each of the elements 11 and 12 has a plurality of load absorbing formations 13 formed thereon. The elements 11 and 12 and the load absorbing formations 13 are formed of solid rubber, in the sense that there are no voids or air bubbles or air pockets contained therein.

A plurality of said formations 13 extend transversely across the width of the element 11 and a plurality of said formations 13 extend perpendicularly along the length of the element 11. The overall effect created is of a grid or waffle pattern.

One valuable feature of the protector is that the formations 13 on the upper surface 14 of the elements 11 and 12 are offset relative to the formations 13 on the lower surface 15. This is illustrated in more detail in Fig. 5. Furthermore, when element 11 is superimposed on element 12, the formations 13 on the upper surface 14 of element 12 are offset relative to the formations 13 on the lower surface 15 (i.e. the facing surface) of element 11. The feature of the offset formations 13 has the effect of dissipating some energy transversely outwardly towards the edges of the elements 11 and 12 when a load is dropped from above, due to the formations 13 including continuous transverse ribs across the width of the protector.

There are three discrete spaces or intervals 17 along the length of the element 11 which are free of formations 13. These spaces 17 ease flexing of the protector 2 thereby making it more comfortable to a wearer or user.

Apart from the difference in size, the element 12 is broadly speaking similar to the element 11 , except it includes only one space 17.

Optionally the protector 2 may further include foam pads (not shown) spaced over the elements 11 and 12 (but not between them) and within the pouch 10. These pads enhance the aesthetics and comfort of the protector 2.

The protector 2 may also include curved strips of metal (not shown) disposed within the rubber matrix of the elements 11 and 12. Essentially, these strips provide a skeleton for the element which enables it to be curved to complement the curve of the top of a user's foot. A further function of the metal strip is to readily permit flexing in one direction but to resist flexing in the other direction, thus such strips might be arranged to extend across and not along the protector 2. The elements 11 and 12 of a protector 2 as described above may have a thickness (i.e. the dimension between surfaces 14 and 15) of about 1 to 1.5 mm and formations 13 about 2 to 2.5 mm high, giving an overall thickness for each element of about 5 to 6 mm. The formations 13, being ribs, are preferably semicircular in cross section, however other cross sections may be used. The ribs 13 may be spaced about 10 mm apart such that a generally square grid pattern is formed. However other grid patterns of other sizes and shapes may be provided. Furthermore, formations 13 other than ribs may be provided, including discrete cylindrical, frustoconical, conical or other shapes. A typical length for element 11 is about 12 cm and for element 12 is about 17 cm, although these dimensions may vary as they will depend on the particular size and type of protective footwear the protector is to be attached to. Similarly the widths of the elements 11 and 12 will also vary depending on the environment for the protector.

An advantage of the protector indicated above is that it is light and flexible yet is particularly effective at directing the energy of a falling object away from a user's foot. Clearly, the amount of rubber in a protector as described above having a relatively thin section with ribs thereon is reduced compared to the size of a section that would be normally expected of a protector of this material. Thus the invention allows for a savings in materials cost. The combination of the use of energy-absorbing material, the load-absorbing formations, and the absence of internal voids or air pockets results in a protector which can be extremely highly absorptive of energy. In other words, when an object is dropped thereon the protector absorbs the impact and does not (to any more than a minimal extent) rebound therefrom. Moreover, the simple solid moulded construction affords an extremely inexpensive product.

The metatarsal protector shown in Fig. 8 is not designed to be contained in a pouch, but to be an integral part of safety boot 1 , positioned between the lining and upper of the boot. To this end, protector 2 is fixedly connected to a conventional metal toe-cap 21 , in a manner described in more detail below, in order that the protector and toecap combination can be incorporated into boot 1 during manufacture as a single integral item. This allows secure interengagement between the two and ensures that there is no risk of an unprotected area of the metatarsal region of the wearer's foot between protector 2 and toecap 21.

Protector 2 consists of two resilient rubber elements 11 and 12 fabricated from energy-absorbing NBR material. Both elements are of flattened plate-like form with approximately straight lateral edges 22 which taper inwardly towards curved posterior edge 23. The elements are manufactured in one piece with a small flexible linking element 20 to ensure they remain together after fabrication.

The upper surface 14 of lower element 12 and the lower surface 15 of upper element 11 are respectively provided with a regular grid of linear rib-like projections 13, projecting approximately 4.5mm from their respective surfaces. The opposed surfaces (upper surface of upper element 11 and lower surface of upper element 12) are free of projections, to avoid "shadowing" of the pattern of projections 13 on the upper and lower surface (the lining) of the boot upper 4.

When upper element 11 is folded down to lie over lower element 12 projections 13 on the two elements come into contact with one another, and the grids are disposed such that they are offset one relative to the other when elements 11 and 12 are superimposed, thus assisting in energy dissipation as earlier described. The peripheral portions of the grids of projections 13 towards outer edges 22 and 23 are chamfered (e.g. by machining during the manufacturing process) such that, when superimposed and incorporated into an article of footwear, edges 22 and 23 of, respectively, elements 11 and 12 are able to taper together towards each other, to avoid any abrupt discontinuities in the boot upper around the protector. Likewise elements 11 and 12 feature chamfered areas 24 running laterally across their anterior portions as shown, which allow the elements to taper anteriorly towards one another to "feather" the protector into the toecap area. To assist this smooth feathering, lower element 12 is provided with a thicker anterior strip 25 and thicker side portions 26 depending downwardly therefrom in use, against which thicker portions the anterior edge 27 of upper element 11 abuts when the elements are assembled. At the very anterior edge of lower element 12 a thinner toe strip 28 is provided, extending laterally across the element and running into side portions 26. This toe strip is fixed to the inside face at the posterior edge of toecap 21 , by gluing or similar, and ensures that there is little or no surface discontinuity between the protector and the toecap on either the upper or lower surface.

To avoid the difficulties that may be associated with placement of the protector between the boot upper and the lining, the protector (and the toecap) may be attached by way of adhesive to the underside of the upper before the lining is lasted. After lasting, it can be difficult to pull back the upper far enough to enable placement of the protector.

Fig. 9 shows the assembled protector and toecap combination, the smooth surfaces being evident in this cross sectional view.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.

Claims

CLAIMS:

1. A metatarsal protector including at least one element which is made of energy absorbing material selected from the group of energy absorbing rubber, energy absorbing plastics, and energy absorbing foam.

2. A metatarsal protector according to claim 1 of butyl and/or nitrile rubber.

3. A metatarsal protector according to claim 1 or claim 2, comprising at least a first and a second said element of energy absorbing material superimposed one upon the other, each of said elements having a flattened configuration with two major surfaces.

4. A metatarsal protector according to claim 3, wherein the first element has a relatively larger surface area and the second element a relatively smaller surface area.

5. A metatarsal protector according to any preceding claim, the at least one element having a plurality of load absorbing formations projecting outwardly proud of at least one of the surfaces thereof.

6. A metatarsal protector according to claim 5 insofar as dependent on claim 3 or claim 4, wherein the surfaces of the elements which face one another are each provided with said plurality of load absorbing formations projecting outwardly proud thereof, whilst said opposed surfaces are substantially free of projections.

7. A metatarsal protector according to claim 5 or claim 6, said plurality of load absorbing formations projecting to a lesser extent from said at least one element in areas adjacent the periphery of said at least one element than in central areas thereof.

8. A metatarsal protector according to any one of claims 5 to 7, the load absorbing formations containing no gas pockets.

9. A metatarsal protector according to any one of claims 5 to 8, at least some of said load absorbing formations on one surface of an element being offset relative to the corresponding formations on the other surface of the element.

10. A metatarsal protector according to any one of claims 5 to 9, the load absorbing formations being of elongate substantially linear or rib-like configuration.

11. A metatarsal protector according to claim 10, each surface of the element having a first set of rib-like formations extending in one direction and a second set of rib-like formations extending in another direction substantially perpendicular to said first direction, so that said rib-like formations form a grid pattern.

12. A metatarsal protector according to any one of claims 5 to 11 , including at least one discrete space or interval across the length of at least one element which is free of load absorbing formations.

13. A metatarsal protector according to any preceding claim, further including a flexible pouch within which the at least one energy absorbing element is contained.

14. A metatarsal protector according to claim 13, wherein the protector includes at least one further pad element contained within said pouch, in order to improve the aesthetics of the protector and to enhance the comfort of the protector.

15. A metatarsal protector according to any preceding claim, at least one of the rubber elements including support means.

16. A metatarsal protector according to claim 15, the support means comprising elongate strips of metal disposed internally within the element, to enable the protector to be shaped so as to complement the shape of the foot of a wearer.

17. A metatarsal protector according to claim 15 or claim 16, said support means arranged and designed to permit flexing in one direction but resist flexing in another direction.

18. A metatarsal protector according to any preceding claim, including a toe strip at an anterior edge thereof for attachment to a toecap.

19. A metatarsal protector according to claim 18, shaped and sized in the vicinity of said toe strip such that, when attached to a toecap, the outer surface of the protector is substantially flush with that of the toecap.

20. A metatarsal protector according to claim 18 or claim 19, said toe strip including side portions which, in use, form downwardly depending anterior portions of said protector for attachment to the toecap.

21. A metatarsal protector according to any preceding claim in combination with a toecap.

22. An item of footwear including the metatarsal protector of any preceding claim.

23. A metatarsal protector substantially as herein described with reference to any one of the embodiments represented in drawing figures 2 to 9.

24. An item of footwear substantially as herein described with reference to any one of the embodiments represented in drawing figures 2 to 9.