EP0792594A1

EP0792594A1 - Improved vapor-permeable footwear

Info

Publication number: EP0792594A1
Application number: EP19970200540
Authority: EP
Inventors: Diego Caletti; Antonio Ferrarese
Original assignee: WL Gore and Associates SRL
Current assignee: WL Gore and Associates SRL
Priority date: 1996-03-19
Filing date: 1997-02-25
Publication date: 1997-09-03
Also published as: IT241753Y1; ITVI960024V0; JPH1057103A; ITVI960024U1

Abstract

It has been found that inserting a layer of a micro-capillary felt (7) in the space defined between the outsole (2) and midsole (3) allows footwear to be provided with a soft plantar zone and a very flexible outsole (2) so as to contribute to the evacuation of vapor resulting from evaporation of perspiration of the foot and enhance comfort for the user while still having the advantages derived from the application of the vapor-permeable and water-tight material (6). More specifically, the footwear according to the invention has an outsole (2), a midsole (3), and an upper. Between the midsole (3) and outsole (2) is a layer of a liquid water-impervious and water vapor-permeable material (6). The outsole (2) and the midsole (3) can have a plurality of holes (4,4') for letting vapor from the interior migrate to the outside of the footwear.

Description

FIELD OF THE INVENTION

The present invention provides improved vapor-permeable footwear which is provided with a layer of a vapor-permeable and water-tight material.

BACKGROUND OF THE INVENTION

Footwear made of synthetic materials, especially footwear of foamed polyurethane, plastics and similar materials have become very popular in recent years. This footwear, especially footwear having a plastic outsole and textile upper, has two major disadvantages. On the one hand, the use of plastics completely inhibits water-vapor transmission, i.e., breathability hereinafter, through the outsole with all the well known negative consequences for the user. One the other hand, the use of a textile fabric for making the upper makes such footwear permeable for liquids so that it cannot be recommended for use in bad weather or on wet terrain.
Footwear to obviate these disadvantages is known wherein an inner layer of a water-vapor-permeable and liquid water-tight material, such as a material known as stretched porous polytetrafluoroethylene is provided at the sole and/or upper. This material contributes to a free passage of water vapor from the interior to the outside of the footwear, while offering an absolutely impermeable barrier against water penetration.
In some cases, the prior art footwear has an inner lining of a pouch type that covers completely the interior of the footwear. In other cases, the above-mentioned vapor-permeable and water-tight material is provided to cover the top part of the upper or at least a portion of the same.
In certain applications. the above-mentioned vapor-permeable and water-tight material is inserted between the outsole and midsole, the outsole and midsole having a plurality of holes for the passage of vapor through the outsole.

SUMMARY OF THE INVENTION

It has now been found that inserting a layer of a micro-capillary felt in the space defined between the outsole and midsole allows footwear to be provided with a soft plantar zone and a very flexible outsole so as to contribute to the evacuation of vapor resulting from evaporation of perspiration of the foot and enhance comfort for the user while still having the advantages derived from the application of the vapor-permeable and water-tight material.
More specifically, the footwear according to the invention has an outsole, a midsole, and an upper. Between the midsole and outsole is a layer of a liquid water-impervious and water vapor-permeable material. The outsole and the midsole can have a plurality of holes for letting vapor from the interior migrate to the outside of the footwear.
The felt is positioned on top of the liquid water impervious, water vapor permeable layer in the space defined between the outsole and midsole. This construction allows a piece of footwear to be provided that offers a greater comfort to the user while retaining all advantages of water-tightness and vapor permeability inherent in this type of footwear.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 schematically shows a sectional view of footwear according to the invention;
Figure 2 shows a sectional view of footwear of Figure 1 in an orthogonal plane.

DETAILED DESCRIPTION OF THE INVENTION

Reference numeral 1 in the drawings designates an upper of footwear attached to an outsole that has a grip sole 2 and a midsole 3.
The midsole and the grip sole each has a plurality of holes 4 and 4' for the passage of vapor resulting from perspiration of the foot from the interior to the outside of the footwear.
A lining layer 5 is eventually provided in the interior of the shoe. The lining is internally fixed to the upper and is preferably in the form of a pouch.
A layer 6 of a water vapor-permeable and liquid water-tight material such as stretched porous PTFE is adhered to grip sole 2, between the grip sole and the turned-up part of the upper so as to contribute to the removal of vapor while blocking the ingress of liquids from the outside.
This layer of material 6 is preferably adhered along the perimeter so that the middle portion with holes 4 remains free.
The invention is characterized by inserting in the space defined between the outsole and midsole a layer 7 of a micro-capillary felt, e. g., a needle-loomed monofilament felt e. g., of polyester, with a weight of 110 to 200 g/m².
The use of this micro-capillary felt offers an advantage of substantially increasing the surface for transmission of vapor owing to the availability of the internal microscopic cavities so as to remove, through diffusion, the vapor from the surrounding zones and to evacuate it through the holes in the grip sole.
The felt layer can be, e.g., 2 to 3 mm thick.
The insertion of such felt into the space defined between the outer sole, and midsole contributes to the formation, at the contact with the foot, of a layer of a soft material and enables the grip sole to be made as thin and compact as possible thus ensuring good flexibility of the outsole.
It is preferred that midsole 3 be made of three layers, with two outer layers 8 enclosing a layer 9 of a so called spacer material, e.g., of polyamide in the form of a plurality of wavy filaments or, in general, rough filaments so as to maintain a spacing between the two outer layers and define a plurality of passages contributing to the transfer of vapor, without its absorption, toward micro-capillary felt layer 7 so as to further enhance breathability.
As a result, footwear is provided that offers an improved comfort and convenience for the user.
It will be further apparent that dimensions and materials used may vary depending on specific application.

Claims

Footwear of the type having a midsole, and an outsole made with a plurality of holes for the passage of vapor, and a layer of a liquid impermeable and water vapor-permeable material provided between the outsole and a midsole, characterized by the fact that a layer of felt is present between the outsole and midsole.
The footwear of claim 1, characterized by the fact that said felt is a micro-capillary felt.
The footwear of claim 2, characterized by the fact that the midsole has at least one layer defining a plurality of passages contributing to the transfer of vapor toward the micro-capillary felt.
The footwear of claim 2, characterized by the fact that said felt is a needle-loomed monofilament felt.
The footwear of claim 4, characterized by the fact that said felt is of polyester, with a weight of 110 to 200 g/m².