GB2242607A - Disposable biodegradable absorbent footwear insert - Google Patents

Abstract

A disposable biodegradable absorbent footwear insert comprises a shaped laminar element the outline of which approximately matches that of an insole and is composed of fibrous or other absorbent biodegradable material (12) having a binding layer (13) on one face for contact with the foot of a wearer and an adhesive element (15) on the opposite face. The said opposite face may also have a reinforcing or binding layer (14) which, in place of an adhesive element, may be formed with a non-bonding adhesive over the whole of its area.

Description

A DISPOSABLE BIODEGRADABLE ABSORBENT FOOTWEAR INSERT The present invention relates generally to an improved and novel footwear insert intended for use in circumstances where the wearer may not wish to wear traditional socks.

It is traditional for footwear made of leather or imitation leather materials to be worn with the interposition of an insulating layer of knitted fabric constituted by socks or stockings. The physical function performed by the socks or stockings can be characterised in two specific features: First, the socks or stockings offer a certain degree of mechanical resilience to help to absorb impacts transmitted through the footwear to the wearer's feet, via the socks or stockings, from the normal everyday activities such as walking, running, kicking etc; secondly, the socks or stockings fulfil a further function in assisting in the absorption of moisture from the wearer's skin generated by transpiration during the course of the day.

It is well known that human skin is provided, over the whole of the area of the body, with a plurality of pores through which moisture is transpired during the normal evolution of the organic processes taking place in and under the epidermal layer. Such transpiration varies as function of distance from the vital organs in the thoracic cavity and reaches a maximum at the extremities, namely scalp hands and feet. As far as the scalp is concerned, this is usually covered by natural hair which absorbs the moisture and regulates the transfer to the atmosphere.

The hands are usually exposed to the atmosphere and transpiration by perspiration causes no uncomfortable or inconvenient effects, except in times of stress when the generation of moisture can increase beyond the capacity of the immediate environment to absorb it by evaporation resulting in the well known phenomenon of sweaty palms.

As far as the feet are concerned, however, the tradition of encasing them in footwear often results in problems due to the limited ability of the footwear materials to allow the transmission of internally generated moisture leading to a build up of such moisture within the footwear and saturation of the skin of the foot which, at the elevated temperatures which can occur, create an ideal environment for unwanted fungal growth. This condition is known, for apocryphal reasons, as athlete's foot. Although socks and stockings act to alleviate this problem they do not avoid it altogether.The situation. however, is considerably worsened by the fashion for ladies to wear no protective garments on their legs, especially during the summer months, since this deprives them of the even partly absorbent effect of such garments and direct contact between the foot and the materials from which footwear is made (which, naturally, have a very low coefficient of thermal conductivity for obvious reasons) results in an increase in temperature and therefore a corresponding increase in the rate of perspiration whilst at the same time experiencing a reduced ability to absorb the moisture or to dispose of this by evaporation.

It has been known, of course, in special circumstances, to provide for the introduction of an additional insole into footwear, especially sporting footwear, for the purpose of increasing the mechanical resilience of the sole and heal to cushion the foot against shocks encountered in sporting activities. It is also known to provide an insole having activated charcoal in relatively thick layers the function of which is to neutralise the odours generated by the material activity which proceeds from the above-mentioned warm moist conditions encountered within inadequately porous footwear. Neither of these known insoles, however, are capable of fulfilling a requirement to enable wearers to use footwear without socks or stockings and nevertheless maintain a degree of comfort from the absorption of perspiration generated within the footwear during use.The present invention addresses this problem and seeks to provide a solution thereto in a manner which is economical and acceptable both from an aesthetic and a practical point of view.

According to one aspect of the present invention, therefore, there is provided a disposable, biodegradable, absorbent footwear insert comprising a shaped laminar element the outline of which approximately matches that of an insole, comprised of fibrous or other biodegradable absorbent material having a binding layer on at least one face for contact with the foot of a wearer and an adhesive element or layer on the opposite face for retaining the element in position within the shoe or other footwear.

The essential requirements of the wearer, for minimum intrusion into the interior volume of the shoe, to allow the foot to occupy this volume unobstructed, are therefore met by the insert of the present invention which, being biodegradable and disposable allow for ready and rapid exchange of inserts after use for a fresh insert.

Preferably the said adhesive element on the opposite face of the absorbent laminar element is constituted by a self-adhesive strip protected by a removable backing layer. Such self-adhesive strip is provided in order to assist the insert in maintaining its position within the shoe bearing in mind the forces which are transmitted between the sole of the foot of a wearer and the sole of the shoe during normal use, and the possibility that the insert, especially since being made as thin as is practically possible, will have relatively little structural stiffness, may tend to move within the shoe under the wearer's sole in the absence of such retaining means.

Of course, in order to minimise this problem, there may further be provided reinforcement means extending preferably longitudinally of the insert to resist buckling or rather distortion upon insertion or removal of a foot or upon the exertion of forces between the wearers sole and the upper surface of the footwear sole during normal, or even abnormal use.

Such reinforcements may be constituted by a laminar reinforcement element formed as an intermediate layer of the insert between the upper and the lower surface layers thereof, or may in fact be constituted by one of the said surface layers themselves.

There may also be further provided a lightly adhesive layer on both opposite faces of the element so that, upon insertion of a foot into the shoe, the absorbent insert bonds lightly to the sole of the foot to retain this in position against disturbing forces. Providing the upper and lower surface layers are caused to adhere to their facingcooperative surfaces of the foot and the shoe respectively, any potential delamination of the element due to the transmission of forces can be tolerated provided it does not detrimentally affect the absorbency of the fibrous material from which the intermediate layers are made.

In embodiments of the invention in which the body of the element is composed of a plurality of layers of fibrous absorbent material the outer players may further be bonded together through the thickness of the element in some convenient way. This may be achieved, for example, by impressing a pattern of bonding lines on the outer layers, with a selected adhesive material impregnating these lines and the fibrous filler material constituting the body of the insert.

As mentioned above, it is preferred that the thickness of the element varies over the area thereof from a minimum comprising, in the extreme case, solely the two outer surface layers, to a maximum substantially wholly composed of the interior absorbent players and the outer surface layers.

At least the outer surface layer exposed to the foot of the wearer in use of the element may be composed of a semi-permeable membrane. Such membranes are known to permit the transmission of moisture in one direction selectively and to resist the transmission of moisture in the other direction. Such materials are known and used for purposes such as child's nappy liners where an even greater amount of moisture frequently needs to be transmitted to an absorbent body.

The present invention can also be considered to be constituted by the use of a shaped porous multi-layer laminar element having a minimum thickness in correspondence with the ball and heel of the foot of a wearer as an insole to absorb perspiration from the wearer's foot. Furthermore, the present invention also comprehends a footwear insole for use in place of socks to insulate a wearer's foot from direct contact with the sole of the shoe and to provide maximum comfort without detrimentally affecting the use of the foot thereby intruding into the volume occupied by the wearer's fcot within it.

One embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a footwear insert formed as an embodiment of the present invention; Figure 2 is a sectional view taken on the line ii-ii thereof; Figure 3 is a sectional view taken on the line iii iii thereof; and Figure 4 is an enlarged transverse sectional view taken on the line iv-iv.

Referring now to the drawings the insert shown is generally indicated with the reference numeral 11 and comprises a main body 12 of absorbent fibrous filler material, having an upper layer 13 which conveniently may be a semi-permeable membrane, and a lower layer 14 which may be a rather more stiff reinforcing layer, but nevertheless extremely thin. Beneath the reinforcing layer 14 is a self-adhesive strip 15 coated with the backing strip 16. The dimensions of these components have, in the drawings, been exaggerated for the sake of clarity.

With reference to Figure 1 it can be seen that the outline 17 of the element 11 approximately follows the shape of the interior of a shoe, and has areas of different thickness which are identified by shading and outlined, namely a first area 18 constituting the area of contact of the toes, and an area 19 constituting the area of contact of the ball of the foot, which is joined by a narrow isthmus 20 to a further enlarged area 21 constituting the area of contact of the heel. Around the perimeter of the element there is a ridge 22 of greater thickness, and there is a further major area 23 of greater thickness in PUK89028/JH/JMS correspondence with the arch of the foot. The shaded areas 18, 19, 20, 21 are all of minimum thickness, in the extreme this may be no more than the thickness of the upper and lower layers 13, 14 although, in practice, a narrow layer of the filler 12 may also be incorporated in these areas such that their overall unstressed thickness is about half to one millimetre, namely approximately the same thickness as the knitted layer of a sock or stocking.

Claims (11)

1. A disposable, biodegradable absorbent footwear insert comprising a shaped laminar element the outline of which approximately matches that of an insole, composed of fibrous or other biodegradable absorbent material having a binding layer on one face for contact with the foot of a wearer and an adhesive element on the opposite face for retaining the element in position within the shoe or other footwear.

2. An absorbent footwear insert as claimed in Claim 1, in which the said adhesive element on the opposite face of the absorbent laminar element is constituted by a selfadhesive strip protected by a removable backing layer.

3. An absorbent footwear insert as claimed in Claim 1 or Claim 2, in which there are further provided reinforcement means extending longitudinally of the insert to resist buckling or other distortion upon insertion or removal of a foot from the footwear.

4. An absorbent footwear insert as claimed in Claim 3, in which the said reinforcement is constituted by a laminar reinforcement element constituting an intermediate or surface layer of the element.

5. An absorbent footwear element as claimed in any preceding Claim, in which there is further provided a lightly adhesive layer on both opposite faces of the element.

6. An absorbent footwear element as claimed in any preceding Claim, in which the body of the element is composed of a plurality of layers of fibrous absorbent material and the outer layers are bonded together through the thickness of the element.

7. An absorbent footwear element as claimed in any preceding Claim, in which the thickness of the element varies over the area of the element from a minimum comprising solely the two outer surface layers to a maximum substantially wholly comprised of the interior absorbent layers and the outer surface layers.

8. An absorbent footwear element as claimed in any preceding Claim, in which at least the surface layer exposed to the foot of the wearer in use of the element is composed of a semi-permeable membrane.

9. The use of a shaped porous multi-layer laminar element having a minimum thickness in correspondence with the ball and heel of the foot of a wearer as an insole to absorb perspiration from the wearer's foot.

10. A footwear insole for use in place of socks to insulate a wearer's foot from direct contact with the sole of a shoe and provide maximum comfort without detrimentally affecting the absorbency of the fibrous material from which the intermediate layers are made or by intruding into the volume occupied by the wearer's foot within the shoe.

11. A footwear insole substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.