EP1728447A1

EP1728447A1 - Method for improving the traction properties of a footwear sole and a footware sole

Info

Publication number: EP1728447A1
Application number: EP05076263A
Authority: EP
Inventors: Juhani Varjotie
Original assignee: Solegrip Oy
Current assignee: Solegrip Oy
Priority date: 2005-06-01
Filing date: 2005-06-01
Publication date: 2006-12-06

Abstract

A method is disclosed for improving the traction properties of a footwear sole (1), the underside of the footwear to this end incorporating at least one traction area (2). The invention is implemented by fabricating the traction area (2) such that a mechanical-friction-improving-material (3) is attached to the underside surface of the sole material.

Description

The present invention relates to a method for improving the traction properties of a footware sole, the underside of the footware sole to this end incorporating at least one traction area fabricated by attaching a mechanical-friction-improving material to the underside surface of the sole material. The invention also relates to a footware sole having at least a portion thereof formed into a traction area serving to improve the frictional properties of the footware, the traction area being fabricated by way of attaching a mechaniccal-friction-improving material to the underside surface of the sole material.
Slipping during activities/motion outdoors may invoke accidents that are reflected in the community as substantial costs due to hospital care, loss of working capability and wellbeing. A major portion of falling accidents take place in the wintertime on slippery roads and yard areas. The greatest risk group is formed by people aged 50 and above that also suffer from falling injuries more serious than those occurring to young individuals. Many elderly people also have a fear of falling that prevents them from entering outdoors, which obviously is a limitation to their social life. Weather conditions particularly complicated as to the risk of slipping occur at near-zero and rapidly rising/falling temperatures, as well as during snowing or icing precipitation.
For prevention of slipping, different kinds of nonintegrated traction elements dismountably attachable to the underside of footware have been developed. While these devices can increase traction on ice in a significant fashion they suffer from the nuisance of requiring repetitive mounting/dismounting on footware. Such operations are generally complicated to perform. Mechanical traction devices may also become dislodged from the underside of footware. Furthermore, the studs or spikes of the traction devices may scratch interior floors. Also studded footware suffer from this drawback. Hence, such footware is ill suited for walking in banks, shops or other public indoor areas without causing damage to floor surfaces.
An alternative approach to this problem has been attempted by way of improving the sole material of footware so as to make the footware sole coefficient of friction sufficiently high to prevent slipping. To this end, different kinds of high-friction rubber and elastomeric compounds have been developed. It has been found, however, that frictional adhesion between ice and any other material cannot be increased beyond a certain limit. Hence, the increase of footware traction thus achieved is insufficient to prevent slipping and injuries resulting therefrom. Neither have different kinds of improved sole patterns guaranteed reliable traction on ice.
Utility models FI 5885 and FI 6054 relate to the improvement of frictional properties in the wearing surface material of footware sole. Utility model FI 5885 teaches traction improvement through having the footware sole complemented with distinct frictional elements made from a material different from that of the sole body. The frictional elements may be made from, e.g., ceramic materials, polymers such as polyester, polycarbonate, and, further, coarse sand particles, stainless metallic particles or combinations these. According to utility model FI 6054, the material used in the manufacture of the wearing surface of the footware sole has distinct frictional particles compounded therein, either homogeneously or only in a portion of the wearing surface of the sole. A disadvantage of this approach is that the frictional particles become compounded into the entire body of the sole material, not onto the wearing underside of the sole alone. Hence, the method fails improve traction in a controlled fashion, but rather, the frictional properties may vary between different specimen of the same footware type. Another problem is that the footware sole thus manufactured needs a wear-in cycle before gaining its ultimate friction.
From patent publication FR 1.378.208 is known in the art a method of fabricating a footware traction area by way of attaching to the underside surface of the sole a pad of mechanical-friction-improving material. A drawback of this approach, however, is that ice and snow adhering to the sole underside nevertheless degrade the traction of the footware.
It is an object of the present invention to provide a method for improving the traction properties of footware such that footware produced in accordance with the method also provides traction on ice. The method according to the invention is characterized in that onto the mechanical-friction-improving material is applied a thin layer having low adherence to snow and water.
It is a further object of the invention to provide a footware sole with traction properties exceeding those of the art and free from the shortcomings of the prior art. The footware sole according to the invention is characterized by having a thin layer of low adherence to snow and water is applied onto the mechanical-friction-improving material.
The thin snow/water-repellent layer applied to the underside of the footware sole keeps the sole continually impervious thus preventing snow from plugging the interstices between the traction-improving particles.
In the following, the invention is described in more detail with the help of preferred embodiments by making reference to the appended drawings in which

FIG. 1 shows a sectional elevation view of a footware sole according to the invention;
FIG. 2 shows a bottom view of a footware sole according to the invention;
FIG. 3 shows a feasible structure of the footware sole traction pad; and
FIG. 4 shows a preferred embodiment of the invention in two different postures.

Advantageously, the invention is implemented by having the frictional area of footware formed by at least one traction pad 2 attached to underside of the footware sole 1 during the manufacture thereof. The number, shape and size of traction pads may be varied as required. In principle, the entire footware sole may be comprised of a single traction pad. In the embodiment shown in FIGS. 1 and 2, the number of traction pads 2 is four.
The traction pad 2 has a high-friction surface and its attachment to the footware may be accomplished by hot-melt glueing, adhesively, by casting or using any other technique. The traction pad itself is fabricated by adhering to the surface of an elastomeric or other polymeric material, with the help of hot-melt glueing, adhesively, by casting or using any other technique, another material of high mechanical friction coefficient in the form of a hard particle 3 (see FIG. 3) which is made from a metallic material, a ceramic material such as carbide, a polymeric material or any other suitable material. Subsequent to the attachment of the particles, thereon is processed a thin layer 4 (see FIG. 3) serving to repel snow that otherwise tends to adhere to the footware sole. The material of this layer may be any material highly repellent to snow adhering to the sole underside (such as polyurethane). Alternatively, it is also possible to precoat the traction-improving particles with a snow-repellent material. For high friction, one of the most crucial factors is to keep the footware sole free from snow. Omission of the repellent coating allows snow to plug the interstices between the carbide particles 3, whereby footware traction is degraded substantially. Footware manufactured according to the present method offers good traction on ice from the first moment of use. Hence, the footware does not need wear-in as is necessary in prior-art footware fabricated using compounding technique discussed earlier in the text. According to the invention, frictional properties result from the traction caused by the physical particles and the adhesion of the elastomeric layer to ice.
Accordingly, traction pads can be located during manufacture to any underside point of the footware sole. Additional traction pads 2 may also be adapted to the sides of the sole, whereby in normal gait the pads do not make contact to the ground. In slipping, however, the footware tilts laterally thus requiring good traction at its side rather than on its underside. This situation is illustrated in FIG. 4 whose left-side diagram shows how a traction pad located behind the footware heel portion hits ice after the footware tilts in its longitudinal direction to a certain angle during, e.g., slipping backward. In the right-side diagram of FIG. 4 the footware is shown tilted laterally, whereby a traction pad 2 located at the side of the sole gains traction on the icy surface thus preventing the foot from slipping any more.
The invention may utilize the physical properties of polymeric materials such as crystallization or change of tensile elastic modulus. An example of such property change is the crystallization of certain polyurethane grades at temperatures below 0 °C, whereby the material becomes harder thus supporting hard particles embedded in the sole underside and thereby improving mechanical traction of footware on ice. Respectively, at temperatures above 0 °C, the material becomes softer thus allowing the hard particles to embed deeper in the polymer matrix, whereby the hard particles can "conceal" themselves into the maxtrix thus improving frictional traction indoors and avoiding the tendency of the footwear to scratch floor surfaces.
The elasticity of the traction pad 2 augments to repel snow adhering to the footwear underside. Preferably, the traction pads are located in the footware underside surface on such areas that are subjected to flexion. Flexure aids to repel snow from the surface of the traction pads. Obviously, the location of traction pads on the footware underside may be varied as desired.
To a person skilled in the art it is obvious that the invention is not limited to the above-described exemplary embodiments, but rather may be varied within the inventive spirit and scope of the appended claims. Other advantageous applications of the invention may be found, e.g., in trekking footware used for moving in rough terrain and thus requiring lateral traction, e.g, for climbing on hills. To this end, the footware may have traction pads at the sides of its sole as illustrated in FIG. 4, for instance. While having the above description exemplifying the footware traction properties on ice only, it is obvious that the invention may as well be applied to the traction improvement of footware intended for use on other kind of slippery surfaces. Hence, such applications include ship and boat decks, among others.

Claims

A method for improving the traction properties of a footware sole (1), the underside of the footware to this end incorporating at least one traction area (2) fabricated by way of attaching a mechanical-friction-improving material (3) to the underside surface of the sole material, characterized in that a thin layer (4) having low adherence to snow and water is applied onto the mechanical-friction-improving material (3)
A footware sole (1) at least a portion thereof incorporating a traction area (2) serving to improve the traction properties of the footware, the traction area (2) being fabricated by way of attaching a mechanical-friction-improving material (3) to the underside surface of the sole material, character- ized in that the mechanical-friction-improving material (3) is covered by a thin layer (4) having low adherence to snow and water.