Protective boot and sole structure

A sole for a boot and the boot incorporating the sole. The sole provides the wearer of the boot with a level of protection from explosive devices triggered by the wearer stepping on or near the explosive device. Tie sole includes at least one layer of corrugated blast-resistant material. The corrugations provide channels that effectively channel blast gases generated by the explosion of the explosive device sidewardly and so away from the foot of the wearer of the boot. The sole further includes layers of blast-resistant material and a cocoon of material is also provided throughout the upper of the boot to provide a level of protection to the remainder of the wearer's foot

PREFERRED MODE OF CARRYING OUT THE INVENTION A boot having the features of the present invention is generally depicted as 10 in FIG. 1 . Explosive devices that are hidden in the ground and adapted to be exploded by the weight of a person walking on or near the ground where the device is buried are generally called mines The damage that can be caused by a mine is dependent on the type and quantity of the explosive used in the mine. While mines can obviously kill, the purpose of many mines is to only maim the person who is unfortunate to trigger the device. The boot having the features of the present invention is designed to be worn by infantry soldiers or others moving through areas where mines are known or possibly hidden. While no form of wearable protection can protect against all devices that are designed to cause large explosions, the present invention does offer a level of protection that is designed to protect the foot of the soldier from serious damage, such as loss of a foot, if the soldier triggers a mine having a type or quantity of explosive that would maim a person wearing normal footwear. The boot 10 has a substantially standard shaped upper 11 adapted to enclose the foot and ankle of a wearer and a sole 12 . The sole 12 comprises a heel 13 and a fore plate region 14 that extends from a position distal the heel 13 to the toe 15 of the boot 10 . The heel 13 includes at least one corrugated layer of metal-matrix composite material 16 that extends in a plane throughout at least a majority of the heel 13 . Disposed immediately above and below the corrugated layer 16 is at least one layer of planar metal-matrix composite 17 . The combination of the corrugations in the corrugated layer 16 and the respective planar layers 17 defines a plurality of channels 18 that extend transversely across the heel 13 . The channels 18 serve to channel laterally blast gases generated by the explosion of a mine beneath the boot 10 sidewardly and so serve to provide a level of protection to the foot of the wearer in the boot 10 above the corrugated layer 16 . In the depicted embodiment, the metal-matrix composite is formed from woven graphite (preferably, of the type 3K TOW, 380 g/m 2 , M60/T300) impregnated with a polymer containing a metal powder of an alloy including aluminium, nickel and molybdenum. The composite is formed in a method including the steps of: impregnating the graphite with the polymer containing the metal alloy powder; drying the graphite in a drier; passing the graphite through a molten bath of an aluminiun/nickel/molybdenum alloy that is at a temperature to carburise the polymer; and exerting a pressure on the composite to remove the excess metal alloy therefrom The step of exerting pressure on the composite is achieved by passing the composite through a set of rollers that are capable of exerting about 35 to 40 tons on the composite. It will be realised that corrugated layers of other materials could be utilised in the sole of the present invention For example, a polymer impregnated composite or an epoxy impregnated composite could be utilised in certain situations as the corrugated layer in the heel of the sole. Disposed above the corrugated layer 16 in the heel 13 is an upper layer 19 of blast-resistant material which in the depicted embodiment comprises three layers of woven aramid fibre that extend substantially to the periphery of the heel 13 . In the depicted embodiment, the three layers of aramid are each formed from 280 g/m 2 woven aramid held together by a porous coat of hot melt polyurethane adhesive. In the depicted embodiment, the corrugated layer 16 does not extend laterally as far as the upper layer 19 . Rather, a gap is left about the entire periphery of the heel 13 . The fore plate 14 is resiliently flexible and includes at least one corrugated layer of polymer impregnated composite material 21 that extends throughout at least a majority of the fore plate 14 . Disposed immediately above the corrugated layer 21 is at least one layer of non-corrugated polymer impregnated composite 22 . The combination of the corrugations in the corrugated layer 21 and the non-corrugated layer 22 defines a plurality of channels 23 that extend transversely across the fore plate 14 . The channels 23 serve to channel laterally blast gases generated by the explosion of a mine beneath the boot 10 sidewardly and so serve to provide a level of protection to the foot of the wearer in the boot 10 above the corrugated layer 21 . Disposed above the corrugated layer 21 and non-corrugated layer 22 in the fore plate 14 is an upper layer 24 of blast-resistant material which in the depicted embodiment comprises three layers of woven aramid fibre that extend substantially to the periphery of the fore plate 14 . In the depicted embodiment, the three layers of aramid are each formed from 280 g/m 2 woven aramid held together by a porous coat of hot melt polyurethane adhesive. In the depicted embodiment, the corrugated layer 21 does not extend laterally as far as the upper layer 24 . Rather, a gap is left about the entire periphery of the fore plate 14 . While the corrugated layer in the fore plate 14 is adhered to the upper layer 24 using an epoxy adhesive, stitching can also be used to strengthen the adherence of the layers 21 , 22 and 24 together in the fore plate 14 . The sole 13 further includes a ground engaging layer 25 . The layer 25 in the depicted embodiment is formed from rubber and has been vulcanised to the remainder of the sole. The layer 25 has a tread 26 that allows the wearer to walk across ground surfaces likely to be encountered by the wearer. In the depicted embodiment, and as is depicted in FIG. 4 , the layer 25 includes an outer layer 27 and an inner layer 28 . The outer layer 27 is formed from a nitrile rubber white the inner layer 28 is formed from a softer foam rubber. In the depicted embodiment, the nitrile rubber has a specific gravity of 1.6, a Shore A hardness of 85, and a thickness of about 3 mm. The foam rubber, which provides a greater level of comfort to the wearer, has a specific gravity of 0.6 and a Shore A hardness of 40. The boot 10 also includes a cocoon 29 of substantially blast-resistant material that is incorporated into the boot 10 and which is adapted to entirely surround the foot of a wearer of the boot 10 . In the depicted embodiment, the cocoon 29 is formed from two layers of woven aramid fibre (see FIG. 4 ) that extend across the sole 13 of the boot and also up within the upper 11 of the boot 10 . As is depicted in FIG. 1 , the cocoon 29 is disposed between a cotton vamp 31 and the leather outer 32 in the upper 11 . As is depicted in FIG. 4 , the cocoon extends beneath a known in the art comfort sole liner 33 and the remainder of the sole 13 . The layers of woven aramid forming the cocoon 29 are preferably bonded by hot melt polyurethane adhesive and are stitched together using aramid fibre. While not depicted, it can be readily envisaged that the cocoon 29 can include layers of woven ceramic fibres or woven ceramic/glass-ceramic composite fibres and woven aramid fibres. The cocoon 29 is also stitched to the sole about the periphery of the sole 13 to further increase adherence of the sole 13 to the remainder of the boot 10 . An additional layer 34 of blast-resistant material is also provided ill the sole 13 . In the depicted embodiment, the additional layer 34 comprises fifteen layers of woven aramid fibre. In FIG. 4 , however, only four of the layers are depicted for clarity. It will be envisaged that more or less layers could be utilised if desired. The woven aramid fibre layers are bonded together with a hot melt polyurethane adhesive. The sole also includes a still further layer 35 of blast-resistant material or a blast shield. The blast shield 35 is, in the depicted embodiment, formed from alternating layers of woven aramid fibre and woven ceramic fibre. In the depicted embodiment, the bottommost layer 35 a (see FIG. 4 ) of the blast shield 35 is a layer of woven ceramic fibre. It will be appreciated that in the blast shield 35 that the woven ceramic fibre can be replaced with woven ceramic/glass-ceramic composite fibres in another embodiment of the invention. The various layers of the sole 13 are preferably supported in a suitable supporting medium, such as polyurethane or rubber. It will be appreciated that suitable adhesives and stitching can be employed to form the entire boot 10 including its sole 13 and cocoon 29 . A deflector plate, such as is described in the applicant's international application No PCT/SG97/00010, the contents of which are incorporated herein by reference, can also be incorporated into the sole 13 , if desired. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.