WO2008025927A2

WO2008025927A2 - Impermeable shoe

Info

Publication number: WO2008025927A2
Application number: PCT/FR2007/051851
Authority: WO
Inventors: David Xu; Adrien Lagneau
Original assignee: Decathlon
Priority date: 2006-08-28
Filing date: 2007-08-28
Publication date: 2008-03-06
Also published as: FR2905053A1; CN101573057A; FR2905053B1; EP2056687A2; WO2008025927A3; EP2056687B1; CN101573057B; ES2607790T3

Abstract

A purpose of the present invention is an impermeable shoe (1), particularly a hiking shoe, comprising a shank (2), a breathable membrane (3) and an inner liner (4). Said shoe (1) characteristically comprises a layer (5) of open-cell foam having a thickness of at least 5 mm, capable of forming a vertical ventilation space and extending exclusively on either side of the rear and interior of the shoe, intended to enclose the hindfoot area (6) over its entire height. An object of the present invention is also a walking ensemble comprising a shoe (1), particularly a hiking shoe, and at least one removable part (5) which has a layer of open-cell foam having a thickness of more than 5 mm, capable of forming a vertical ventilation space, intended to be added by the user inside the shoe so that it extends exclusively on either side of the rear part enclosing the hindfoot area (6) over its entire height.

Description

WATERPROOF SHOES

The present invention is in the technical field of waterproof shoes suitable in particular for the practice of a sport such as hiking. The need for users to be equipped with waterproof shoes allowing them to evacuate perspiration and / or heat is important whether for reasons of comfort or hygiene. Waterproof footwear, such as athletic footwear such as hiking boots, must protect the feet from shock, external conditions and maintain them to prevent any offensive movement.

Sports shoes, especially hiking, usually have a more covering structure for this purpose, often well above the ankle as classic dress shoes. They are also heavier and therefore provide greater thermal insulation. Moreover, in order to protect the user's foot from the external moisture while ensuring its breathability, it is known to have inside the shoe a breathable membrane, of the type sold under the brand name Sympatex. ® or Goretex®, ie a membrane that is impermeable to water but permeable to water vapor. An impervious shoe known from the state of the art, in particular a sports shoe such as a hiking shoe, comprises a rod on which is positioned a buttress. The buttress prevents the rod from deforming and ensures a good positioning in the shoe. A comfort foam is then placed on the buttress to protect the foot from external aggressions and overlays of different materials in the construction of the rod. Said foam also ensures the maintenance of the foot and the holding of the shoe. Finally, a waterproof and breathable complex composed of a lining, possibly a foam or 3D mesh, and a membrane, is placed on said foam in this order, the membrane in question being in first against said foam. The various previous layers are generally secured by sewing on the top of the rod. In practice, it turns out that the waterproof-breathable membranes implemented as described above have the disadvantage of limiting the evacuation of perspiration produced by the foot, especially to the horizontal of the foot. Conventionally, the perspiration produced by the foot is on average 15 g / hour during an intensive sports activity, and waterproof-breathable membranes can evacuate on average lg to 2g per hour of humidity, less 15% of the total transpiration produced by the foot in one hour.

There is therefore a continuing need for users to have waterproof footwear with improved drainage and moisture removal and / or heat removal capabilities; which functions can be personalized according to the feeling of the user and the conditions in which he practices a particular sporting activity such as hiking.

The present invention aims to provide an improved waterproof shoe overcomes the aforementioned problems. The subject of the present invention is therefore an impermeable shoe, particularly a hiking boot, comprising a rod, a breathable membrane and an inner lining, characterized in that it comprises an open-cell foam layer having a thickness of at least 5 mm, able to form a vertical ventilation space and extending exclusively on either side of the rear and internal part of the boot, intended to wrap the area of the rear foot over its entire height.

The terms open cells and open pores are equivalent. Advantageously, the vertical ventilation space removes perspiration and / or heat from the insole to the upper part of the shoe. Said space is provided on the area of the rear foot so as to be opposite the opening of said shoe for the passage of the foot. The extraction of hot air produced by the foot and / or due to the environment is called the "chimney effect". Indeed, the air warming up tends to rise due to the decrease in its density. Said ventilation space uses this effect to evacuate perspiration and / or heat to the vertical of the foot. "The chimney effect" induces a pull likely to cause an internal depression, which allows to suck fresh outside air for example through perforations above the medial malleolus and external in the shaft of the waterproof shoe. The breathable membrane also allows perspiration and heat to be removed horizontally from the foot, that is to say through the different layers separating the foot from the upper of the shoe. The stem is preferably in a breathable material, such as leather. The buttress of the stem is preferably glued partially on it and perforated to facilitate the evacuation of perspiration and heat to the horizontal.

Preferably, the inner liner is formed of a textile, for example a laminated knit by flame, gluing or sewing on a foam. Preferably the textile is stitched onto the foam to minimize obstacles to vertical and horizontal transpiration paths. The lining, by virtue of its foam, makes it possible to accentuate the "chimney effect" and thus to keep the maximum amount of hot air away from contact with the foot, the textile of the inner lining being preferably in contact with the foot of the user.

The open cell foam is preferably obtained by the so-called "slab stock" process allowing the continuous production of foam by deposition of a mixture on a conveyor belt expanding on its path on said belt. Two preferred processes are used for the production of the foam used according to the invention. These are "Max foam" or "Hennecke Planibloc" processes known in the state of the art.

The open cell foam according to the present invention is preferably based on polyurethane. The process for the foaming reaction can be chemical, for example by adding water to the mixture or physical, for example by adding to the mixture an agent having a low boiling point allowing it to pass rapidly during the manufacture of the foam under its gaseous state. The choice of the chosen expansion method, of a chemical or physical nature, depends on the nature of the polymer to be foamed.

Preferably, the open cell foam is obtained by a chemical process. The mixture thus making it possible to manufacture the foam generally comprises: diisocyanates, polyols, water, blowing agents intermediaries, charges and others. As soon as the mixture is deposited on the conveyor belt, the mixture undergoes in particular two important reactions. Polyols and diisocyanates are liquid at room temperature before reacting. In the first reaction, the diisocyanates react with water to produce carbon dioxide and amines:

(1) RN = C = O + H ₂ O → R-NH ₂ + CO ₂

The released carbon dioxide serves as a blowing agent for foam expansion. In the second reaction, the polyols reacting with the isocyanate groups at the ends of the urea chains produce the polyurethane chains (R1-NH-COO-R2), where R1 is the urea-based segment and

R2 is a polyol.

Depending on the method of manufacture of the foam, it is possible to vary the size of the cells and therefore the permeability thereof.

In an alternative embodiment, the foam layer is a cross-linked open cell foam layer.

The term "crosslinked" is understood to mean that the foam has undergone a crosslinking step during which the polymer chains forming said foam are bonded to each other by bridges or chemical bonds. This crosslinking step is irreversible in that the crosslinked foam no longer strictly speaking has a melting temperature such as a thermoplastic. The crosslinking makes it possible to improve the mechanical performance of the foam, in particular the compressive and tear strength as well as the heat resistance. This property makes it possible to maintain a sufficient vertical ventilation space when the foot of the user bears on it while maintaining good elasticity so that the open-cell foam ensures a good comfort foot home.

In addition, the crosslinking makes it possible to stabilize the foams having large open cells. Thus, the crosslinked open cell foams may have open cells having dimensions greater than one millimeter unreachable with uncrosslinked open cell foams. Logically, the larger the open cell size, the better the air and water vapor permeability.

The crosslinking may be obtained by a chemical process, for example by adding an activating agent at a given temperature, or physical for example by electron bombardment.

In a variant, the opening of the cells of the crosslinked foam layer is obtained, during the crosslinking phase, by explosion of a mixture of gases in a closed chamber, preferably based on hydrogen and oxygen. Advantageously, during this explosion, the residual membranes obstructing the open cells of the foam are redistributed during their fusion on the edges. The foam thus tends to 100% of fully open cells. The air permeability of the foams having undergone this crosslinking-explosion step is considerably improved. The Applicant has found that for two given open-cell foams having substantially the same compressive stress values after the foaming step, the crosslinking-explosion method allows to significantly increase their water vapor permeability.

In addition, the thicker edges are also more resistant which improves the mechanical performance of the foam, especially in compression.

The cells obtained have a substantially circular shape and a diameter greater than 1 mm, or of the order of 2 mm to 5 mm. The size of the open cells obtained is a function of the foaming conditions. However, foams having open cells of which at least one dimension is greater than 1 mm after the foaming process, must undergo a crosslinking-explosion step to set the size of these cells. Without this crosslinking-explosion step, the foam is not stable and sags.

In an alternative embodiment, the foam layer has a water vapor permeability greater than 75 mg / (cm ² · 8h), preferably greater than 100 mg / (cm ² · 8h). The table below gives the results of the AFNOR NF G52-019 standard test, in particular to evaluate the water vapor permeability [mg / (cm ^2, N hours)] of a liner or rod. (eg leather) of a shoe. The values of permeability are recorded every two hours and make it possible to establish the rate of evaporation of the water.

Foams M1 and M2 were tested alone. The principle of this NF G52-019 test is to measure the amount of water evaporated through a sample during a given period and under specific hygrometric conditions.

Tab.l Ml is an open cell foam, at least one of which is greater than 1 mm in size, based on polyurethane, and having undergone an explosion of a mixture of hydrogen and oxygen in a closed room.

M2 corresponds to a conventional open cell foam of the state of the art, whose dimensions are less than one millimeter, based on polyurethane, and used in the manufacture of sports articles such as backpacks and footwear. hiking. M2 did not undergo a crosslinking-explosion operation.

Samples named M1 and M2 in the remainder of the description reproduce the same characteristics described above. The water vapor permeability of M1 is three times greater than the permeability of M2. The open cell foam M1 has an exceptional moisture transfer efficiency compared to the foam M2 illustrating the foams of the state of the art.

In an alternative embodiment, the DC stress 40 necessary to deform the open-cell foam layer by 40% of its initial thickness is greater than 5 KPa on average, preferably greater than 7 KPa on average according to the ISO 3386-1 standard. . The table below gives the results of the tests provided by the ISO 3386-1: 1986 standard entitled "Flexible cellular polymeric materials - Determination of the stress-strain characteristic of compression".

Tab.2

The size CC 40 [kPa] corresponding to the stress to be applied to deform the foam by 40% of its initial thickness.

The size SAG corresponds to the ratio between the stress to be applied to compress the foam by 65% of its initial thickness on the stress to be applied to compress the foam by 25% of its initial thickness: SAG = CC65 / CC25.

Compression stress values for M1 and M2 are very close although M1 have open cells larger than at least 3 times the size of the open cells of M2 foam. Similarly, the value of SAG is very close between M1 and M2, which means that the stress to be applied to deform 65% of their initial thicknesses M1 and M2 is of the order of three times the stress to be applied for a deformation of 25% of said initial thicknesses. The value of SAG here is specific to the behavior of the polymer forming the foams M1 and M2, namely polyurethane. The compressive strength is particularly important in the construction of a shoe since the compression exerted by the foot on the open-cell foam crushes it and reduces its thickness in operation. The thickness of the foam M1 in operation must be sufficient to maintain a vertical ventilation space and exclusively on either side of the rear and inner portion of the shoe. In addition, the open cell foam layer should not be too resistant to compression and deform sufficiently to maintain a good foot reception. This double This objective is achieved by choosing an open-cell foam having a DC stress greater than 5 KPa on average, preferably greater than 7 KPa on average and less than 20 KPa on average according to the ISO 3386-1 standard.

In a variant, the open cell foam layer is hydrophobic.

The foam layer thus has a lower water absorption capacity than a hydrophilic foam layer. The purpose is that the water vapor does not stagnate near the foot of the user but is directly evaporated through the vertical ventilation space formed by said foam over the entire height of the foot. In a variant, the open-cell foam layer comprises a majority of cells at least one of which is greater than 1 mm, preferably in the range of 2 mm to 4 mm.

Dimension in the present text means the length of one of the edges delimiting a cell or the distance separating two edges delimiting the same cell.

The majority of cells means that more than 50% of the cells of said foam layer have at least one dimension greater than 1 mm.

In a variant, the open-cell foam layer has a density of 34 kg / m ³ . In a variant, the open cells of the foam layer are delimited by edges having a thickness of about one millimeter.

In an alternative embodiment, the foam layer has a thickness of at least 10 mm.

In waterproof footwear, especially sports shoes, offered on the market, the "chimney effect" is provided by a vertical space consisting of a set with a membrane, a laminated foam on the textile or three-dimensional textile forming the lining interior, which have an average thickness of the order of 3 mm. According to the invention, the vertical ventilation is thus improved with respect to these known shoes, in very large proportions. In an alternative embodiment, the foam layer comprises vertical channels.

The circulation and the evacuation of the hot air are thus facilitated.

In an alternative embodiment, the foam layer is a single piece asymmetric configuration with respect to a vertical plane corresponding to the median plane of the shoe.

Said piece is asymmetrical so as to marry the best shape of the foot taking into account that the external malleolus of the foot is lower than the internal malleolus. In an alternative embodiment, said part comprises a median cutout in the lower part, corresponding to the area facing the base of the Achilles heel.

The middle notch avoids creating depression on the Achilles tendon.

The shape and size of said piece are adapted according to the type of the waterproof shoe, for example depending on whether it is a hiking shoe or running shoe.

Preferably, said piece is in the form of a butterfly with a notch at its center corresponding to said area facing the base of the Achilles heel. In an alternative embodiment, the foam layer is disposed between the inner liner and the breathable membrane.

Advantageously, the "chimney effect" of the laminated foam on the textile of the inner lining and that of the vertical ventilation layer are cumulative. In addition the waterproof-breathable membrane being after said ventilation layer relative to the foot, it continues to perform its watertight function while not inhibiting the horizontal transfer of the foot of the heat and the perspiration to said ventilation space. This arrangement accelerates the evacuation of hot air to the upper part of the shoe and improves the thermal comfort of the user. In an alternative embodiment, the foam layer is disposed on the outside of the inner liner, being intended to come into contact with the foot. Much of the perspiration and hot air is thus directly routed to the vertical of the foot without having to cross the textile portion of the inner lining before being discharged vertically.

The present invention also relates to a walking assembly comprising a shoe, including hiking, and at least one removable piece, which is an open-cell foam layer having a thickness of at least 5 mm, capable of forming a space vertical ventilation, intended to be reported by the user inside the shoe so that it extends exclusively on either side of the rear portion enveloping the rear foot area over its entire height .

In a variant, said assembly comprises a plurality of removable parts, of different thickness and / or porosity and / or density.

The user can customize the drainage and ventilation he wants according to his feelings or activities. Preferably, said pieces are unique and have an asymmetrical configuration with respect to a vertical plane corresponding to the median plane of the waterproof shoe.

Said removable part may be an open-cell foam layer according to any of the embodiments described above. Preferably, said removable part is an open cell foam layer according to one of the embodiments described above laminated to a textile, such as a knit or a fabric, which acts as an inner lining intended to come into contact directly with the foot.

The present invention will be better understood on reading the description of an exemplary impermeable shoe cited in a non-limiting manner and illustrated by the figures below and in which:

- Figure 1 is a schematic representation, in perspective view, of a hiking shoe;

FIG. 2 is a partial schematic representation of the first example of a hiking boot according to the IMI cutting plane; FIG. 3 is a schematic representation in transparency of the first example of a hiking shoe;

- Figure 4 is a schematic representation of the arrangement on the foot of the single piece creating a ventilation space. FIG. 5 is a schematic representation of a cell of an open-cell foam layer having undergone the crosslinking-explosion step.

The waterproof hiking shoe 1 comprises from the outside towards the inside: a rod 2, a buttress 7, a waterproof breathable membrane 3, an open-cell foam layer 5 and an inner liner 4 locked together for mounting between the insole 8, the first mounting 9 and the outsole 10.

The inner liner 4 preferably comprises a laminated textile 4a on a foam 4b, the textile 4a being intended to be in contact with the foot. Indeed the foam 4b will often be present but can be removed. The inner lining 4 is sewn according to its folded edge with the upper part of the waterproof shoe 1 along the seam line 12.

The open cell foam layer 5 is in the form of a single piece having an asymmetrical configuration with respect to the median plane M of the shoe 1. The foam layer 5 preferably has a butterfly-shaped configuration as shown in Figure 4, and has a cutout 11 according to the median plane M in the lower part facing the base of the Achilles heel. Each "wing" 5a or 5b of said butterfly or foam layer 5 envelops the rearfoot 6 over most of its height. Advantageously, the foam layer 5 is positioned between the inner lining 4 and the breathable membrane 3. Thus, when the foot perspires, particularly in the event of effort, heat and moisture are removed mainly in two directions. Part of the heat and / or moisture is discharged vertically from the foot, along the Y axis. For this, the hot and humid air passes through the textile 4a of the inner lining 4 and is then found in a vertical ventilation space delimited by the foam 4b of the inner lining 4 and especially the open cell foam layer 5. The hot and humid air does not have to pass through the impermeable membrane. breathable 3 to reach the foam layer 5, which is not the case in waterproof shoes known from the state of the art where the transfer of moisture to the horizontal of the foot is curbed by the provision of the breathable membrane and the porous layer 5, which is directly against the rod 2 or the buttress 7, the foam layer 5 then ensuring the function of comfort and mechanical support.

The hot and humid air produced by the foot is then captured and then evacuated into said vertical ventilation space and is no longer in contact with the foot, thereby improving the thermal comfort of the user. By a "chimney effect", the hot and humid air, stored in said space, goes up into the upper part of the shoe and is discharged to the outside. Preferably, perforations are arranged according to the area 4c of the inner liner 4 to accelerate and facilitate the evacuation of perspiration and / or moisture.

Part of the perspiration is also evacuated to the horizontal of the foot along the X axis. The water vapor is then evacuated by passing through all the layers forming the impervious shoe 1 from the inside to the outside. For this purpose it is appropriate to choose breathable materials and achieve perforations in different locations on the shoe 1, such as at the level of the malleolus of the foot of the user. The rod 2 is thus made of leather or in a composite textile.

The different layers forming the impervious shoe 1 whose layers 2, 3, 4, 5 and 7 are cut to the dimensions of the shoe 1 and laminated together by gluing. Preferably the buttress 7 is not laminated on the rod 2, it is secured to the rod 2 by means of spot bonding and perforated. This method of assembly limits less the flow of hot and humid air than assembly by sewing or gluing along the entire surface of said layers.

Preferably, the open cell foam layer 5 has a thickness of the order of 10 mm. It is thus possible to adjust the volume of the ventilation space by varying the thickness, the shape and the size of the cells of the foam layer 5, or by arranging vertical channels therein. The preferred open cell foam layer is crosslinked, especially of the M1 type. At During this crosslinking step, the foam layer 5 was blown up in a closed chamber of a mixture of gases, preferably based on a mixture of oxygen and hydrogen in order to distribute the membranes on the edges. remaining following the expansion step. This crosslinking-explosion improves the air and water vapor permeability of the foam layer 5. FIG. 5a schematically shows some open cells of a crosslinked open cell foam layer 13. explosion. The cell 14 here has a substantially pentagonal shape and is delimited by five edges 15a, 15b, 15c, 15d and 15e. Depending on the nature of the foamed polymer and the initial mixture as well as the expansion and crosslinking-explosion conditions, it is possible to vary the shape, cell size, length and thickness of the edges. The edge 15a has a thickness el of the order of 1 mm and a length L1 in the range of 2 mm to 4 mm. The inner window 16 of the pore 13 has a length L2 ranging from 2 mm to 4 mm and is delimited by the inner edges of the edges 15a to 15e. Applicant has selected this Ml-type open cell foam because it gives outstanding results in water vapor permeability while providing compressive strength and comfort meeting the criteria of shoe construction. The foam layer 5 is preferably hydrophobic so that the water vapor is very little absorbed in said layer 5 and evaporates more rapidly from it to the atmosphere.

In a variant not shown, a foam is secured to the foam 4b of the inner liner 4 by spot bonding so as to enlarge the vertical ventilation space and thus improve the thermal comfort of the user. Said foam is preferably 2 mm thick. In a variant not shown, the foam layer 5 is removable and detachably fixed by any means known from the state of the art, preferably to the textile 4a of the inner lining 4. It will thus be possible to provide foam layers of size, density and thickness varied according to the activity and feeling of the user, he will have in his shoe to customize his comfort. In a variant not shown, it is possible to laminate, for example by gluing, according to the surface of the breathable membrane 3 a protective knit to strengthen it, especially as the layers entering the construction of the shoe 1 are offset from each other and may damage it. The waterproof-breathable membranes currently marketed are 80% of the time alone and are not laminated with other materials, and their users have to transform them. There are also on the market waterproof-breathable membranes sold in a waterproof and breathable complex, which is respectively composed in this order of a lining for example a protective knit, possibly a foam or a mesh in three dimensions and the waterproof-breathable membrane. Depending on the quality and the targeted cost of the waterproof shoe 1, the breathable membrane 3 may be alone or replaced by a waterproof and breathable complex as described above.

Claims

1. Waterproof footwear (1), in particular for hiking, comprising a rod (2), a breathable membrane (3) and an inner lining (4) characterized in that it comprises a layer (5) of cellular foam having a thickness of at least 5 mm, capable of forming a vertical ventilation space and extending exclusively on either side of the rear and inner part of the boot, intended to envelop the area of the rear foot (6) over its entire height.

2. Shoe (1) according to claim 1, characterized in that the open cell foam layer (5) is crosslinked.

3. Shoe (1) according to claim 2, characterized in that the opening of the cells of the crosslinked foam layer (5) is obtained, during the crosslinking phase, by explosion of a gas mixture in a chamber closed, preferably based on hydrogen and oxygen.

4. Shoe (1) according to any one of claims 1 to 3, characterized in that the foam layer has a water vapor permeability greater than 75 mg / (cm ² .8h), preferably greater than 100 mg / (cm ² .8h).

5. Shoe (1) according to any one of claims 1 to 4, characterized in that the DC stress 40 necessary to deform by 40% of its initial thickness the open cell foam layer (5) is greater than 5 KPa on average, preferably greater than 7KPa on average according to ISO 3386-1.

6. Shoe (1) according to any one of claims 1 to 5 characterized in that the foam layer (5) is hydrophobic.

7. Shoe (1) according to any one of claims 1 to 6 characterized in that the open cell foam layer (5) comprises a majority of cells of which at least one of the dimensions (L1, L2) is greater at 1 mm, preferably in the range of 2 mm to 4 mm.

8. Shoe (1) according to any one of claims 1 to 7 characterized in that the open cell foam layer (5) has a density of about 34 Kg / m3.

9. Shoe (1) according to any one of claims 1 to 8 characterized in that the open cells of the foam layer (5) are delimited by ridges (15a, 15b, 15c, 15d, 15e) having a thickness (el) of the order of 1 mm.

10. Shoe (1) according to any one of claims 1 to 9 characterized in that the foam layer has a thickness of at least 10 mm.

11. Shoe (1) according to any one of claims 1 to 10 characterized in that the foam layer comprises vertical channels.

12. Shoe (1) according to any one of claims 1 to 11 characterized in that the foam layer (5) is a single piece of asymmetric configuration with respect to a vertical plane corresponding to the median plane of the shoe.

13. Shoe (1) according to claim 12 characterized in that the piece (5) has a central cutout (11) at the bottom, corresponding to the area facing the base of the Achilles heel.

14. Shoe (1) according to any one of claims 1 to 13 characterized in that the foam layer (5) is disposed between the inner liner (4) and the breathable membrane (3).

15. Shoe (1) according to any one of claims 1 to 13 characterized in that the foam layer is disposed on the outside of the inner liner (4), being intended to come into contact with the foot.

16. Walking assembly comprising a shoe (1), in particular hiking, and at least one removable piece (5), which is an open-cell foam layer having a thickness greater than 5 mm, capable of forming a ventilation space vertical, intended to be reported by the user inside the shoe so that it extends exclusively on either side of the rear portion wrapping the rear foot area (6) over its entire length. height.

17. Walking assembly according to claim 16 characterized in that it comprises a plurality of removable parts (5), of different thickness and / or porosity and / or density.