IT202300024072A1 - WATERPROOF AND BREATHABLE SOLE STRUCTURE - Google Patents

Description

WATERPROOF AND BREATHABLE SOLE STRUCTURE

DESCRIPTION

Field of invention

The present invention relates to the footwear sector and, in particular, refers to a waterproof and breathable sole structure.

State of the art

Generally, a footwear item comprises a sole structure, positioned below the intended use of the footwear item, designed to support the user's foot, allowing the weight of the foot to be transferred to the ground and reducing the stresses transmitted to the foot by the ground. This structure also comprises an upper assembly, positioned above and enveloping the foot, joined to the sole structure, which, in turn, may be monolithic, i.e., constructed as a single piece, or may comprise a tread joined to a midsole.

Nowadays, in order to increase comfort, the prior art provides footwear articles comprising waterproof and breathable sole structures which, in particular, are provided with a breathable area equipped with through openings and a functional, waterproof and breathable layer, sealed in a waterproof manner along the perimeter of the breathable area.

The perforations allow vaporous sweat produced by the wearer's foot to escape through the sole structure, while the aforementioned waterproof and breathable functional layer, essentially a membrane, has the dual function of preventing water from entering the footwear from the outside and simultaneously allowing vapor to escape. In other words, the membrane acts as a barrier that prevents water from entering the footwear through the perforations, making it waterproof, but allows vapor produced by the wearer to escape through the perforations, making it vapor-permeable or breathable.

Sole structures of the above type are described, for example, in patents EP 0382904 B1 and EP 0858270 B1 and in patent application WO 98/51177.

The aforementioned functional layer is generally made of polymeric materials such as polyurethane (PU), polyester, expanded polytetrafluoroethylene (e-PTFE), whose flexural strength is put to the test during use of the footwear item.

The sole structure, in fact, is subject to repeated flexing that is transmitted to all the components that make it up and which mainly affect the forefoot area, which is the same area where the aforementioned transpiration zone is located and therefore where the membrane is present. In fact, the area of the foot where the majority of the sweat glands on the sole of the foot are located and which is therefore most affected by sweating is precisely the forefoot area.

More precisely, there is an area of the forefoot of the sole structure that is most affected by mechanical stresses such as the aforementioned flexions, which essentially corresponds to an area of the user's forefoot that is most affected by sweating, which is commonly referred to as the "maximum flexion zone" and which can be identified, for example, according to known methodologies as described below.

The aforementioned stresses can therefore cause the membrane to rupture at the maximum flexural zone, attributable to its structural failure, for example because a certain number of flexural cycles is exceeded, such as 2,000,000 cycles, according to the method presented in chapter 8.4.2 of the ISO 20344:2011 standard. Disadvantageously, the membrane rupture corresponds to the loss of waterproofness of the sole structure.

Definitions

- The term midsole refers to an element or layer, of any nature, placed between the sole and the insole, according to the general definition given in the EN ISO 19952:2005 standard, point 106, page 18.

- A material, and therefore a component considered in isolation made of such material, is waterproof if there are no points where water can penetrate when the material is subjected to a pressure of at least 1 bar for at least 30 seconds. In particular, waterproofness is assessed as the resistance of a specimen, essentially made of the material under examination, to the penetration of pressurized water, according to the method described in the EN1734 standard. According to this method, a sample of the aforementioned material is fixed to a container and used to close the container, in which the container, which is equipped with a pressurized water inlet, is filled with water so as to subject the face of the aforementioned sample facing the inside of the container to a hydrostatic pressure of 1 bar, at which point this condition is maintained for 30 seconds. In detail, the aforementioned sample is The sample is clamped between the opening of the container and a retaining ring, in which the sample and the retaining ring are covered with silicone rubber seals, and in which pressurization is achieved by forcing water from a reservoir into the container by means of a flow of compressed air regulated by a valve with a pressure gauge displaying the reached pressure. The surface of the sample outside the container is then observed. The absence of penetration points, consisting of the formation on that surface of drops with a diameter between 1 mm and 1.5 mm, indicates the impermeability of the sample and therefore of the aforementioned material. If necessary to prevent deformation of the sample, a grid of a square mesh with sides no greater than 30 mm, made of synthetic material, made with wires with a diameter between 1 mm and 1.2 mm, is fixed to it.

- Vapor permeability is the quantity of vapor that passes through a material as a result of a partial pressure gradient. ISO 20344-2004, in chapter 6.6 "Determination of water vapor permeability," relating to safety footwear, describes a test method consisting of fixing a sample of the material under test so as to close the opening of a bottle containing a certain quantity of solid desiccant, i.e., silica gel, in which the bottle is subjected to a strong current of air in a conditioned atmosphere. The bottle is rotated to mix the solid desiccant and optimize its drying action on the air contained in the bottle. The bottle is weighed before and after the test period to determine the mass of moisture that has passed through the material and been absorbed by the solid desiccant. Vapor permeability to water vapor, expressed in milligrams per square centimeter per hour [mg/cm<2>/h], is then calculated based on the measured mass of moisture, the area of the bottle opening and the test time.

- In the context of the present invention and in accordance with common practice, the terms "permeable/permeable to vapor", "permeable/permeable to water vapor", and the like are to be understood as equivalent to each other and synonymous with "breathable". Furthermore, in the context of the present invention, the terms "breathable zone" and "breathable portion" mean an area or portion permeable to water vapor as indicated above, consisting of a breathable material, such as leather, skin, fabric, non-woven fabric, etc., but also an area or portion equipped with at least one through opening.

- A water-repellent material is one that allows a drop of water to slide across its surface. This occurs because a very high contact angle is generated between the surface and the drop, preventing absorption by the material itself in the absence of hydrostatic pressure. A surface's water repellency is generally measured by the contact angle between the water droplet and the surface and its surface tension.

- In the following description, in accordance with what was previously explained and in analogy to the anatomy of the foot, the forefoot area A, the midfoot area M and the rearfoot area R of a sole structure and of a footwear item, schematically depicted in the example in figure 1a, are defined as follows:

The forefoot is located at the front of the foot, the midfoot is located at the arch, and the hindfoot is located at the back. Specifically, the forefoot generally includes portions of a shoe corresponding to the toes and the junctions between the metatarsals and proximal phalanges, while the hindfoot generally includes portions of a shoe corresponding to the heel bone.

An article of footwear (or a sole structure) further comprises a portion corresponding to the outside of the foot (lateral portion) and a portion corresponding to the inside of the foot (medial portion), each of which extends through the rearfoot, midfoot, and forefoot portions, generally corresponding to opposing portions of the article of footwear ideally separated by the Brannock axis, which can be defined as the axis that bisects the foot in a posterior-anterior direction (rearfoot-forefoot). The rearfoot, midfoot, and forefoot regions are not intended to demarcate precise areas of an article of footwear or a sole structure, but are intended to give a general representation of the areas of an article of footwear or a sole structure useful in describing the invention.

- The portion of the forefoot area subject to maximum flexion, i.e. the aforementioned maximum flexion zone, corresponds to a portion of the sole structure that extends close to, or astride, the flexion line defined in ISO 20344:2004(E), paragraph 8.4, page 64; in practice, the aforementioned flexion line is approximately orthogonal to the longitudinal axis, which for simplicity can be identified with the Brannock axis, and intersects it at a third of the length of the latter starting from the toe of the sole. Therefore, approximately, the maximum flexion zone is found approximately 1/3 of the overall length of the sole structure, starting from the toe, and is easily identified without equipment, simply by holding the sole structure in your hands and flexing it to approximately 1/3 of its length.

Alternatively to the above, the aforementioned zone of maximum flexion can be identified in greater detail by referring to the construction lines, indicated by r, s, t, defined below by considering the projection onto the ground of the internal profile of a sole structure, represented in figure 1 together with the bones of a user's foot, where it is indicated by P.

- - construction line r which identifies the axis of flexion of the foot, which passes through point B which represents the end of the first metatarsal facing the proximal phalanx of the big toe, and anteriorly (towards the tip of the foot) to the distal phalanx of the fifth toe, preferably tangent to the upper end of this, and which intersects the aforementioned projection, towards the outside of the foot, at a point Y. In practice, the construction line r does not cross the fifth toe: in fact, the latter is affected almost entirely by the flexion of the foot during walking.

- - construction line s, which passes halfway along the proximal phalanx of the big toe, anterior to point B and at a distance from point B equal to approximately 15-20 mm for a men's foot of size 42 with reference to French sizes, measured parallel to a longitudinal axis b which for simplicity is comparable to the aforementioned Brannock axis which bisects the foot in the forefoot-hindfoot direction. The construction line s also intersects the distal phalanx of the fourth toe between the anterior end and its midline. Thus constructed, the construction line s intersects the construction line r at a point O and the projection P at a point X. Point O lies on the plane containing the aforementioned projection of the internal profile of the sole structure onto the ground.

- - construction line t extends from the point O of intersection between construction line r and construction line s and intersects the projection P at a point Z, so that the arc YZ has a length equal to approximately half the length of the arc XY.

The above relationship, expressible as:

LXY = 2?LYZ

? obtained from experimental evidence, according to which:

the XY arch develops along a portion where the bending stress of the foot and the sole structure is maximum, and

the fourth toe, as previously seen for the fifth toe, is almost entirely excluded from flexion during walking, due to the anatomy of the human foot and, therefore, the YZ arch sized in this way identifies a portion where the flexion stress of the foot and the sole structure, although assuming a lower value than that developed in correspondence with the XY arch, still represents a non-negligible stress for the membrane.

The construction lines s, t therefore delimit the aforementioned area of maximum flexion of the sole structure.

Summary of the invention

The technical problem underlying the present invention was to provide a waterproof and breathable sole structure with characteristics capable of overcoming one or more of the drawbacks cited above with reference to the prior art.

In accordance with the invention, the aforementioned problem is solved by a sole structure of a shoe, comprising at least one breathable portion suitable for the passage of water vapor and in correspondence with which a waterproof and water vapor permeable membrane is arranged, wherein the aforementioned at least one breathable portion is arranged externally to a portion of the forefoot of the sole structure known as the maximum flexion zone.

Essentially, the proposed solution consists of placing at least the portion of the membrane located in correspondence with the aforementioned at least one breathable portion, and preferably the entire membrane, relatively far from, and in any case external to, the area of maximum flexion of the sole structure, while at the same time promoting the confluence of sweat in the vapor phase towards the aforementioned breathable portion or breathable portions if more than one is present.

In particular, this waterproof and breathable sole structure, which has an internal side designed to face the inside of the shoe and an external side designed to face the environment outside the shoe, comprises:

a tread having an upper surface on the side of the said inner side and a lower surface on the side of the said outer side,

one or more ventilation channels

a functional area comprising its own breathable portion suitable for the passage of water vapour, a membrane impermeable to water and permeable to water vapour and a sealing area surrounding the aforementioned breathable portion to which the aforementioned membrane is sealed in a waterproof manner, therefore by means of an appropriate seal,

which is characterized by the fact that

the aforementioned one or more ventilation channels are designed to direct water vapour towards the surface of the aforementioned membrane facing the aforementioned internal side,

and from the fact that

the aforementioned breathable portion of the aforementioned functional area is entirely arranged externally to a portion of the forefoot corresponding to the aforementioned area of maximum flexion.

In accordance with the above, it can therefore be said that the aforementioned functional area is overall impermeable to water and permeable to water vapor.

Preferably, the aforementioned membrane is entirely arranged externally to the aforementioned zone of maximum flexion.

Preferably, the aforementioned sealing area is located entirely external to the aforementioned maximum deflection area.

Preferably the aforementioned sealing area is substantially flat.

Preferably, the aforementioned sealing area is substantially smooth.

Preferably, the aforementioned membrane is sealed in a waterproof manner to the aforementioned sealing area by gluing with a suitable adhesive, by co-molding or by means of a third element, for example a sealing ring, made of waterproof material, such as polyvinyl chloride - PVC, or ethylene vinyl acetate - EVA, which partially overlaps the membrane and partially the sealing area.

Preferably the above membrane is made of PU, polyester, polyethylene or ePTFE.

Preferably, the aforementioned functional area is equipped with a cavity in which the aforementioned membrane is housed.

In accordance with the invention, the aforementioned sealing area may be external or internal to the aforementioned cavity, if present. In the case of a sealing area internal to the cavity, the aforementioned membrane is preferably sealed by gluing or co-molding, while in the case of a sealing area external to the cavity, the membrane is preferably sealed by means of the aforementioned third element such as the aforementioned sealing ring glued between the membrane itself and the sealing area which extends outside the aforementioned cavity, surrounding it. It should be noted that, in accordance with the above, a sealing ring can also be used in the absence of the aforementioned cavity.

Preferably, the aforementioned sole structure comprises a breathable element or a layer of breathable material arranged in correspondence with the aforementioned membrane, above or below it, and/or a layer of material equipped with channels facing, in use, towards the ground, arranged above the aforementioned membrane, which is preferably water-repellent and which overall is also indicated as a protective element.

Preferably, the aforementioned breathable element or layer of breathable material is a polyester felt or a three-dimensional fabric.

Preferably, the aforementioned one or more ventilation channels have a predominantly longitudinal direction, for example they are directed from the rear foot (or rear area of the tread) or from the forefoot (or front area of the tread), towards the aforementioned breathable portion.

The one or more ventilation channels may be more or less straight, wavy, curved, or broken, or a combination of these, but always preferably with a predominantly longitudinal direction. Preferably, the one or more ventilation channels have a width between 2 mm and 10 mm.

Preferably, the one or more ventilation channels mentioned above have a depth of between 1 mm and 5 mm.

Preferably, the aforementioned one or more ventilation channels have a bottom at the level of the aforementioned sealing area.

Preferably, the one or more ventilation channels are delimited by ribs made as a single piece with the tread, for example by injection moulding or compression moulding of a polymeric material such as rubber, polyurethane (PU), thermoplastic polyurethane (TPU), ethylene vinyl acetate (EVA), thermoplastic rubber (TR).

As previously indicated, the term "breathable portion" (or transpiration zone) refers to a portion or area that can be permeable to water vapor as indicated above, as it is made of a breathable material, or it can be a portion or area equipped with at least one through opening which, as such, also allows the passage of water vapor.

In this regard, in the case of a through opening or through openings, it should be said that they preferably have a circular or ellipsoidal shape, although other shapes, for example a quadrangular one, are not excluded.

Preferably, the aforementioned at least one through opening has a width between 2 mm and 30 mm.

Preferably, the aforementioned at least one through opening is positioned at least 14 mm from an internal edge of the sole structure so as to leave a sufficiently wide gap to ensure sealing of the membrane and bonding to any other components of the sole structure or to an upper assembly. In this regard, the aforementioned sealing area preferably has a width between 4 mm and 12 mm.

In accordance with one embodiment of the invention, the aforementioned breathable portion is included between the aforementioned upper surface and the aforementioned lower surface of the aforementioned tread, particularly extending from the upper surface to the lower surface of the tread. In this case, the breathable portion is preferably, but not exclusively, located at the midfoot of the sole structure or at the forefoot of the sole structure anterior to the aforementioned maximum flexion zone. However, the possibility of providing the breathable portion located at the hindfoot, precisely inside the latter, or positioned between the midfoot and hindfoot, is not excluded. Two breathable portions of the aforementioned type may also be provided, in which case the present sole structure comprises a second functional zone arranged on the aforementioned tread and which comprises its own breathable portion (second breathable portion of the sole structure) suitable for the passage of water vapor, a second waterproof and water vapor permeable membrane and a second sealing zone surrounding the aforementioned breathable portion to which the aforementioned membrane is sealed in a waterproof manner, wherein the aforementioned breathable portion of the aforementioned second functional zone is entirely located externally to the aforementioned maximum flexion zone, wherein preferably the aforementioned second membrane is entirely located externally to the aforementioned maximum flexion zone, and wherein more preferably the aforementioned second sealing zone is entirely located externally to the aforementioned maximum flexion zone. In the case of two breathable portions, one is preferably placed in correspondence with the midfoot of the sole structure, the other in correspondence with the forefoot of the sole structure anterior to the aforementioned maximum flexion area.

In accordance with the aforementioned embodiment of the present invention, the aforementioned one or more ventilation channels are arranged on the aforementioned upper surface of the tread and are in fluid communication with the aforementioned functional zone and possibly with the aforementioned second functional zone.

In accordance with a variant embodiment of the invention, the present sole structure comprises a shock-absorbing element, substantially a midsole, having an upper surface, a lower surface coupled to the aforementioned upper surface of the tread and a second breathable portion suitable for the passage of water vapor, wherein the aforementioned breathable portion of the aforementioned functional area (first breathable portion) is included between the aforementioned upper surface and the aforementioned lower surface of the tread, wherein the aforementioned second breathable portion is included between the aforementioned upper surface and the aforementioned lower surface of the midsole, wherein the aforementioned one or more ventilation channels are arranged on the aforementioned upper surface of the midsole and are in fluid communication with the aforementioned second breathable portion which, preferably, is provided with at least one through opening, and wherein the aforementioned breathable portion and the aforementioned second breathable portion are substantially overlapping each other.

In accordance with the aforementioned embodiment of the invention, the present sole structure may optionally comprise a cavity (second cavity) corresponding to the aforementioned second breathable portion.

Preferably, the aforementioned sole structure comprises a breathable element or a layer of breathable material, preferably water-repellent, arranged in correspondence with the aforementioned second breathable portion and possibly housed in the aforementioned second cavity.

In accordance with a further embodiment of the invention, the present sole structure comprises a midsole having an upper surface and a lower surface coupled to the aforementioned upper surface of the tread, wherein the aforementioned breathable portion of the aforementioned functional zone is comprised between the aforementioned upper surface and the aforementioned lower surface of the midsole, wherein the sole structure comprises a second breathable portion suitable for the passage of water vapor comprised between the aforementioned upper surface and the aforementioned lower surface of the tread, wherein the aforementioned one or more ventilation channels are arranged on the aforementioned upper surface of the midsole and are in fluid communication with the aforementioned breathable portion which, preferably, is provided with at least one through opening, wherein the breathable portion of the aforementioned functional zone (first breathable portion) and the aforementioned second breathable portion are substantially overlapping each other.

In accordance with yet another embodiment of the invention, the present sole structure comprises a midsole having an upper surface, a lower surface coupled to the aforementioned upper surface of the tread and a second breathable portion suitable for the passage of water vapor and included between the aforementioned upper surface and the aforementioned lower surface of the midsole, wherein the aforementioned one or more ventilation channels comprise a first series including one or more channels arranged on the aforementioned upper surface of the midsole and a second series including one or more channels arranged on the aforementioned lower surface of the midsole, wherein the channels of the aforementioned first series and of the aforementioned second series are in fluid communication with the aforementioned second breathable portion which, preferably, is provided with at least one through opening, wherein the aforementioned breathable portion of the aforementioned functional area (first breathable portion) is ... is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion which is in fluid communication with the aforementioned second breathable portion. included between the aforementioned upper surface and the aforementioned lower surface of the tread, and in which the aforementioned breathable portion and the aforementioned second breathable portion are staggered and not overlapping.

Preferably, in the latter case, the aforementioned breathable portion of the aforementioned functional zone (first breathable portion) and the aforementioned second breathable portion extend in correspondence with the rearfoot and the midfoot of the sole structure respectively.

Preferably, the aforementioned one or more channels of the aforementioned first series extend from the aforementioned second breathable portion to the forefoot and the aforementioned one or more channels of the aforementioned second series extend from the aforementioned second breathable portion to the rearfoot.

Preferably the above-mentioned zone of maximum deflection is delimited by construction lines s, t as previously defined.

In accordance with yet another embodiment of the invention, the present sole structure comprises a midsole having an upper surface, a lower surface coupled to said upper surface of the tread, and a lateral edge comprised between said lower surface and said upper surface, wherein said breathable portion of said functional zone is comprised between said upper surface and said lower surface of the midsole, wherein said one or more ventilation channels are arranged on said upper surface of the midsole and are in fluid communication with said breathable portion, and wherein said sole structure is provided with one or more transverse passages extending on said lower surface of the midsole from said breathable portion to said lateral edge.

Brief description of the figures

Further features and advantages of the invention will be better highlighted by examining the following detailed description of some preferred but non-exclusive embodiments, illustrated for indicative and non-limitative purposes, with the support of the attached drawings, in which:

- figure 1 schematically shows a projection on the ground of the internal profile of a generic sole structure with corresponding construction lines r, s, t designed to define, in a known way, a portion of the forefoot of the sole structure known as the maximum flexion zone, together with the bones of the foot of a user;

- figure 1a schematically shows the aforementioned internal profile of a generic sole structure with respective forefoot, midfoot and rearfoot areas;

- Figure 2 is a schematic plan and top view of a first embodiment of a sole structure comprising a tread, according to the present invention;

- Figure 3 is a schematic longitudinal sectional view of the sole structure according to the present invention, taken along the plane A-A of Figure 2;

- Figure 4 is a schematic cross-sectional view of the sole structure according to the present invention, taken along the plane B-B of Figure 2;

- Figure 5 is a schematic view, in perspective and in separate parts, of a sole structure comprising a tread and a midsole, in accordance with a variant embodiment of the invention, in which the midsole is shown both in a bottom view with an upper assembly indicated by dotted lines, and in a top view;

- Figure 6 shows a schematic perspective view of the sole structure of Figure 5 with the aforementioned upper assembly indicated by dotted lines;

- Figures 7a and 7b show a schematic cross-sectional view of a detail of the sole structure of Figure 5, taken along the C-C plane of Figure 6; according to two variant embodiments of the invention;

- figure 7c is a schematic view of a detail of the sole structure of figure 5, specifically of the aforementioned midsole, in accordance with a variant embodiment of the invention;

- figures 8a and 8b show respective schematic views of a detail of the present sole structure, specifically of the aforementioned midsole, according to two different configurations, in accordance with a further embodiment variant of the invention;

- Figure 9 is a schematic view of the present sole structure comprising a tread and a midsole, in accordance with a further embodiment of the invention, in which the midsole is shown both in a bottom view with an upper assembly indicated by dotted lines, and in a top view;

- figure 10 is a schematic view of a detail of the sole structure of figure 9, specifically of the aforementioned midsole, in accordance with a variant embodiment of the invention;

- Figure 11 is a schematic view of the present sole structure comprising a tread and a midsole, in accordance with a further embodiment of the invention, in which the midsole is shown both in a bottom view with an upper assembly indicated by dotted lines, and in a top view.

Detailed description of the invention

The so-called maximum flexion zone of a sole structure or a shoe structure, like that of a foot, is located in correspondence with the forefoot and can be identified in various ways, including the one using the construction lines r, s, t previously described in detail and illustrated in figure 1, which will be referred to below together with figure 1a which schematically shows the areas of the sole structure identified as forefoot A, midfoot M and rearfoot R.

In particular, in figure 1, P indicates the projection on the ground of the internal profile of a generic sole structure which, therefore, can be a sole structure according to the known art or a sole structure according to the present invention, the aforementioned zone of maximum flexion being uniquely and equally delimited, in both cases, by the construction lines s, t.

With the above in mind, the present invention provides a waterproof and breathable sole structure, comprising a waterproof and water vapor permeable membrane positioned in correspondence with a breathable portion suitable for the passage of water vapor and towards which the confluence of sweat in the vapor phase is favored, wherein the aforementioned breathable portion is positioned externally to the aforementioned maximum flexion zone. In practice, in accordance with the invention, the aforementioned membrane is at least partially, and preferably entirely, positioned externally to the aforementioned maximum flexion zone.

With reference to the example in figures 2-4, 1 indicates a sole structure of a shoe according to the present invention, which has an internal side 2 intended to face the inside of the shoe and an external side 3 intended to face the environment outside the shoe.

In detail the structure of sole 1 includes:

a tread 4 having an upper surface 5 on the side of the aforementioned internal side 2 and a lower surface 6 on the side of the aforementioned external side 3, a functional area to prevent the ingress of water from the aforementioned external side 3 towards the aforementioned internal side 2, comprising its own breathable portion 7 suitable for the passage of water vapour extending from the upper surface 5 to the lower surface 6, a membrane 10 impermeable to water and permeable to water vapour and a sealing area 9 which surrounds the breathable portion 7 and to which the membrane 10 is sealed in an impermeable manner, therefore by means of an appropriate seal;

a plurality of ventilation channels (but it must be said that in accordance with the invention, a single ventilation channel can also be envisaged) to direct, from the side of the aforementioned internal side 3, water vapour towards the surface of the membrane 10 facing the internal side 2, in the specific case towards the breathable portion 7, in which each ventilation channel, indicated with 8, has a preferably predominantly longitudinal direction, and

in which the breathable portion 7 is entirely arranged externally to the aforementioned area of maximum flexion.

In this regard, in the example of figure 2, 11 indicates an internal edge of the sole structure 1, which substantially corresponds to the projection P, on the ground, of the internal profile of the generic sole structure represented in figure 1 and to the same internal profile of the generic footwear structure represented in figure 1a.

In the embodiment in accordance with the example of Figures 2-4, as mentioned, the sole structure according to the present invention essentially comprises a breathable portion which is equipped with a plurality of through-openings 12 (but it should be noted that in accordance with the invention, a single through-opening can also be provided) positioned posteriorly, that is, towards the rear of the sole structure, with respect to the area of maximum flexion. More correctly, it is precisely the through-openings 12 that define the breathable portion 7 of the sole structure 1, which is contained within the midfoot. More rigorously, a breathable portion can be defined in general as the minimum area whose outline contains all the aforementioned through-openings. It should be added that the aforementioned outline, which is a closed line, can be appropriately modified to make it convex, thus facilitating the process of creating the membrane and any protective elements as described below, in which "convex outline" means a "convex outline." This means that the space delimited by this outline contains all the segments that connect the aforementioned through-openings. It should also be added that in all embodiments according to the present invention, a breathable portion may be made of a breathable material, such as leather, fabric, non-woven fabric, etc., in place of the through-openings. In this case, the outline of a breathable portion substantially coincides with the outline of the breathable material (or materials, if more than one).

In the case of through openings, it should be noted that they preferably have a circular or ellipsoidal shape, although other shapes, such as a quadrangular shape, are not excluded.

Furthermore, the through openings 12 have a width preferably between 2 mm and 30 mm and are preferably arranged at least 14 mm from the internal edge 11 of the sole structure 1, so as to leave a margin free of openings sufficiently large to ensure the sealing of the membrane 10 and the gluing to any other components of the sole structure or to an upper assembly intended to be bonded to the present sole structure.

The above information regarding multiple through-openings also applies if only one through-opening is provided or if a breathable material is used instead of the through-openings.

As regards the sealing area 9, which extends externally along the perimeter of the aforementioned breathable portion, it should be said that it has a width preferably between 4 mm and 12 mm and that the through openings 12 are preferably positioned internally 4 mm from the sealing area.

Furthermore, the sealing area 9 is preferably arranged entirely externally to the aforementioned area of maximum flexion and is preferably substantially flat and/or smooth so as to make the seal between the membrane 10 and the tread 4 more secure.

The membrane 10 is attached to the sealing area 9. In addition to being waterproof and permeable to water vapor, it is sealed in a waterproof manner to the aforementioned sealing area by gluing with a suitable adhesive, by co-molding, or by means of a third element, for example a sealing ring made of waterproof material, such as polyvinyl chloride - PVC, or ethylene vinyl acetate - EVA, which partially overlaps the membrane and partially the sealing area, as will be illustrated in more detail below.

The membrane 10, which is essentially a functional layer, is preferably made of polyurethane (PU), polyester, polyethylene or ePTFE.

As illustrated in the example of figures 2-4, the sole structure 1 can also be equipped with a cavity 13, however optional for the sole structure in accordance with the present invention, arranged in correspondence with the aforementioned functional area, in which the membrane 10 is housed.

Consequently, the aforementioned sealing area can be external or internal to the aforementioned cavity, if present. In the case of a sealing area internal to the cavity, the aforementioned membrane is preferably sealed by gluing or co-molding, while in the case of a sealing area external to the cavity, the membrane, as mentioned above, is preferably sealed by means of a sealing ring glued between the membrane itself and the sealing area, which extends outside the aforementioned cavity, surrounding it, as illustrated in the examples in Figures 2-4 where the aforementioned sealing ring is not shown.

It should be noted that, in accordance with the above, a sealing ring can also be used in the absence of the aforementioned cavity.

In the sealing area 9, the ventilation channels 8 converge and are interrupted, so as not to interfere with the seal of the membrane 10 on the tread 4.

With regard to the ventilation channels 8 in particular, it should be added that they can have a more or less rectilinear path, or wavy, curved, broken or a combination of these, but always with a predominantly longitudinal direction and that they are defined by ribs 14 which, depending on the ventilation channels, can be predominantly continuous or interrupted, for example when one or more ventilation channels cross, as in the example in figures 2-4.

The ribs 14 are preferably made as one piece with the tread 4, for example by injection moulding or compression moulding of a polymeric material such as rubber, polyurethane (PU), thermoplastic polyurethane (TPU), ethylene vinyl acetate (EVA), thermoplastic rubber (TR).

In particular, it is also possible to create the tread by direct injection onto the upper, using a preformed insert equipped with ventilation channels, loaded into the mold. This way, the ventilation channels are already created on the insert, for example by compression molding, and therefore are not created during the tread molding process, which can thus be speeded up and simplified. Creating ventilation channels by direct injection onto the upper, in fact, without using a preformed insert, would require particular attention to temperature, pressure, and process time, and could lead to potential defects: for example, closed channels, not visible from the outside because the inside of a sole structure created by direct injection onto the upper is practically inaccessible to the eye.

The ventilation channels 8, which are directed from the rear foot (or rear area of the tread) and from the forefoot (or front area of the tread), towards the aforementioned breathable portion, have a width preferably between 2 mm and 10 mm and a depth preferably between 1 mm and 5 mm.

Furthermore, the ventilation channels 8 preferably have a bottom at the level of the sealing area 9. In practice, the ventilation channels 8 are smoothly connected to the sealing area 9, meaning that steps between the ventilation channels and the sealing area are practically avoided, which could cause unwanted stagnation, with the consequent risk of condensation of sweat in the vapor phase. In fact, the sweat in the vapor phase coming from the ventilation channels 8 collects in correspondence with the sealing area 9 and the breathable portion 7.

In particular, in accordance with the example in figures 2-4, the sealing area 9 is in low relief by an amount H preferably between 1 and 5 mm with respect to the upper surface of the ribs 14, so as to create a cavity that receives the sweat in the vapor phase coming from the ventilation channels 8. In particular, the aforementioned cavity is defined below by the sealing area 9 and the membrane 10, and above by the aforementioned upper assembly.

Inside the cavity is placed a breathable material, for example polyester felt, three-dimensional fabric, etc., which provides support to the upper assembly without precluding perspiration, or a non-breathable material but equipped with channels facing, in use, towards the ground and which guide the sweat in the vapor phase coming from the ventilation channels 8 towards the through openings 12.

More generally, it can be said that, in accordance with the invention, the present sole structure can comprise a breathable element or a layer of breathable material arranged in correspondence with the membrane, above or below it, and/or a layer of material equipped with channels facing, in use, towards the ground, arranged above the membrane, which is preferably water-repellent and which, overall, is also indicated as a protective element.

Bearing in mind the above, it should be noted that the depth of the cavity 13 is preferably equal to the total thickness of the membrane 10 and any protective materials or elements, where present. Therefore, the template of the cavity 10 is obtained as a negative offset of the internal edge 11 of the sole structure 1, so as to leave at least 10 mm of gluing margin between the tread 4 and the upper assembly, with the cavity 13 having a longitudinal extension preferably between 5% and 50% of the length of the tread 4 and appropriately connecting the edges thus obtained with a radius of curvature preferably between 2 and 10 mm.

In the example shown in figures 2-4, the aforementioned breathable portion or transpiration zone containing the through openings 12, which can be said to be not physically but only ideally demarcated and which is designed with sharp edges only for practicality, is located in correspondence with the midfoot of the sole structure 1. Although in the example shown in figures 2-4 the aforementioned breathable portion is not physically demarcated, a longitudinal extension of between 5% and 50% of the length of the tread can also be envisaged for it.

In this regard, remembering that the aforementioned ventilation channels have the purpose of promoting the flow of sweat in the vapor phase coming from the upper assembly through a relative insole, towards the breathable portion, the following is observed.

Sweat in the vapor phase, after passing through the insole and reaching the ventilation channels, naturally tends to escape through the openings in the breathable section due to the partial vapor pressure which inside the ventilation channels is higher than that in the external environment.

A further push to the escape of sweat in the vapor phase through the through-holes comes from the compression, acting on the ventilation channels, which occurs as a result of walking.

As mentioned, in accordance with the example in Figures 2-4, sweat in the vapor phase can escape to the outside environment from the through-holes 12 located on the tread 4 at the midfoot of the present sole structure. In this regard, the breathable portion is located approximately in correspondence with the area of the sole structure where the intermediate phase of rolling occurs, i.e., the movement performed by a user's foot (therefore also performed by the sole structure according to the present invention) as it touches the ground starting from the rearfoot, then touching the midfoot, and finally the forefoot. In practice, the thrust of the sweat in the vapor phase is exerted for an initial period that essentially coincides with the first phase of rolling, thus reaching its maximum value in an area of the sole structure that progressively moves from the rearfoot until it reaches the breathable portion in the midfoot. The vapor-phase push of sweat due to compression is then exerted, as the rolling motion progresses, for a second period that essentially coincides with the final part of the rolling motion, thus reaching its maximum value around the sole structure, which progressively moves from the breathable portion in the midfoot until it reaches the forefoot. In this second period, the vapor-phase sweat immediately after the breathable portion is pushed toward the breathable portion, followed by the sweat furthest from it, i.e., at the tip of the sole structure.

As previously reported, this sole structure is intended to be joined to an upper assembly (not illustrated in the example in figures 2-4) on the inner side 2 of the sole structure 1, i.e., at the upper surface 5 of the tread 4, using known techniques such as gluing. In detail, the union between the upper assembly and the sole structure occurs at the aforementioned insole, which is located on the lower part of the upper assembly, between the lower surface of the insole and the upper surface of the sole structure.

The insole is made of breathable material or perforated, preferably at least at the forefoot and/or the aforementioned breathable portion of the functional area of the sole structure. In this way, the vapor-phase sweat produced by the user's foot inside the upper assembly can pass through the insole and reach the breathable portion of the sole structure in a "direct" manner, so to speak, through the holes in the insole (or through the breathable material), and/or in a "indirect" manner, so to speak, through the holes in the forefoot (or through the breathable material), reaching the aforementioned ventilation channels and, from there, reaching the breathable portion of the sole structure.

Advantageously, in accordance with the invention, by placing at least the portion of the membrane corresponding to the breathable portion outside the maximum flexural zone of the sole structure, the risk of breakage of the same is eliminated, and the range of usable membranes is also expanded, including, for example, membranes with a relatively low flexural strength but particularly economical.

It should be added that the design according to the example in Figures 2-4 is also particularly suitable for women's footwear that uses a sole structure comprising a tread and a relatively high heel, the latter applied in the rearfoot area. Generally, the tread thickness for this type of footwear varies between 2.5 mm and 5 mm, and therefore the aforementioned ventilation channels preferably have a depth of between 1 mm and 3 mm. It should be noted that in these types of women's footwear, it would be almost impossible to create a breathable portion in correspondence with the rearfoot.

However, if in the example shown in Figures 2-4 the breathable portion is located at the midfoot, it should be noted that, in accordance with embodiments of the present invention, it can alternatively be located at the forefoot of the sole structure, in front of the area of maximum flexion. In this case, the area of the sole structure where the final phase of rolling occurs essentially coincides with the breathable portion. In practice, the push of the sweat in the vapor phase is exerted in an almost continuous manner from the rearfoot to the forefoot before reaching the breathable portion.

Furthermore, in accordance with the invention, it should be noted that the possibility of providing a breathable portion of the aforementioned type located at the hindfoot, precisely inside the latter, or placed between the midfoot and the hindfoot is not excluded. In the case of a breathable portion at the hindfoot, the present sole structure advantageously offers further freedom of design and may be useful in designs including, for example, particular safety devices, which would make the creation of a breathable portion at the midfoot and/or the forefoot more difficult.

Two breathable portions of the aforementioned type may also be provided, in which case the present sole structure includes a second functional zone arranged on the aforementioned tread, which includes a second breathable portion suitable for the passage of water vapor, a second sealing zone surrounding the aforementioned second breathable portion, and a second waterproof and water vapor permeable membrane sealed in an impermeable manner to the aforementioned second sealing zone, in which the aforementioned second breathable portion of the aforementioned second functional zone is entirely located externally to the aforementioned maximum flexion zone, and in which preferably the aforementioned second sealing zone is entirely located externally to the aforementioned maximum flexion zone, therefore in which preferably the aforementioned second membrane is located externally to the aforementioned maximum flexion zone. In the case of two breathable portions, one is preferably arranged at the midfoot of the sole structure, the other at the forefoot of the sole structure anterior to the aforementioned maximum flexion zone. This solution is advantageous because: allows you to increase the overall breathable area of the sole structure.

With reference to the example in Figures 2-4, it should be added that the aforementioned tread extends lengthwise along a longitudinal axis in the forefoot-rearfoot direction (axis A-A). In this case, the tread is continuous within the sole structure. According to the present invention, however, it is possible to provide a discontinuous tread, that is, comprising two or more portions that are not in contact with one another and are therefore isolated from one another. In the case of a discontinuous tread, the sole structure according to the present invention also comprises a midsole, such as the embodiments described below.

With reference to figures 5, 6, 7a and 7b, a variant embodiment of the present invention is now described in detail.

In particular, the aforementioned figures show a sole structure 100 similar to the sole structure 1 illustrated with reference to the example in figures 2-4, to whose description reference is made, and from which it essentially differs in that it comprises a shock-absorbing element, in practice a midsole indicated with 115 on which ventilation channels 108 are provided in fluid communication with a relative breathable portion of the midsole (second breathable portion), while the tread does not have ventilation channels.

In detail, the sole structure 100 comprises a tread 104 equipped with through openings 112 which define a breathable portion 107 which is surrounded by a sealing area 109 to which a membrane 110 is attached in a waterproof manner, which is entirely similar to the membrane 10 described previously and to which reference is made.

The aforementioned membrane, the breathable portion 107 and the sealing area 109 define a functional area that is overall waterproof and permeable to water vapor.

The aforementioned midsole, indicated with the numerical reference 115, is connected to the tread 104 and comprises an upper surface 116 and a lower surface 117 coupled to the tread 104 in correspondence with the upper surface 105 of the latter.

The midsole 115 preferably extends across the entire surface of the tread 104.

As mentioned above, the midsole 115 is also equipped with a breathable portion, also identified as the second breathable portion and indicated with 118, suitable for the passage of water vapor and extending from the upper surface 116 to the lower surface 117 of the midsole.

The ventilation channels 108 are arranged on the upper surface 116 of the midsole 115 and are in fluid communication with the second breathable portion 118 which, preferably and as illustrated in the examples in the figures, is equipped with through openings 112a, in which the breathable portion 107 of the functional area, therefore of the tread (first breathable portion) and the second breathable portion 118 of the midsole are substantially overlapped and preferably arranged in correspondence with the midfoot, as illustrated in figure 5, although the possibility of providing them in correspondence with the rearfoot or between the midfoot and rearfoot or in the forefoot outside the maximum flexion zone is not excluded.

The ventilation channels 108 have a substantially longitudinal extension and preferably an almost rectilinear path.

Additionally, substantially transverse channels can be optionally provided, as shown in the examples in the figures (not illustrated), also with an almost straight path from the outside of the foot to the inside of the foot and preferably oriented along the aforementioned construction lines r, s, and t described above. This is advantageous because it allows the sole structure to flex in accordance with the movement of the foot during the various phases of the rolling motion.

In practice, the ventilation channels 108 of the midsole 115 of the sole structure 100 perform substantially the same function as the ventilation channels 8 of the tread 4 of the sole structure 1.

The use of the 115 midsole advantageously allows for a lighter sole structure because, since the aforementioned ventilation channels are no longer provided on the tread, the tread itself can be made with a reduced thickness: this leads to a lighter sole structure because the tread is usually made of materials that have a density that can be even two or three times that of the materials used for the midsole.

In the example of figure 5 the ventilation channels 108 are shown in correspondence with the forefoot but, in accordance with the invention, they can be provided alternatively or in addition in correspondence with the rearfoot, furthermore they can also have a similar layout to that of the ventilation channels 8 of the sole structure 1 previously described.

Also in this case, the present sole structure may optionally comprise a cavity 113 (first cavity) arranged on the upper surface 105 of the tread 104 in which the membrane 110 is housed, and it may optionally comprise a cavity 120 (second cavity) arranged on the midsole 115, in particular in correspondence with the aforementioned second breathable portion.

The sole structure according to the present invention can therefore comprise two, one or no cavities.

With particular reference to the cavity 113 provided on the tread 104 and in which the membrane 110 is arranged, it should be noted that the sealing of the latter to the sealing area 109 can take place by gluing, or by means of a sealing element 122, as shown in the example of figures 7a and 7b respectively where the sole structure 100 is illustrated without midsole, in which the sealing element 122 can be, for example, a sealing ring made of PVC or EVA.

A protective element such as a water-repellent polyester felt can also be placed below and/or above the membrane 110.

The protective element, which is therefore optional, can also be defined as a breathable element or layer of breathable material and in the example in figure 5 is indicated with the numerical reference 121.

In particular, a protective element placed above the membrane can serve to "equalize" the difference in height, possibly created by the sealing element, which can be felt by a user, and in general serves to provide additional protection to the membrane that comes into contact with the upper assembly.

A protective element located underneath the membrane shields it from any roughness on the tread surface it comes into contact with. Roughness may be present, especially at the through-holes, due to leaks from the tread molding material and/or due to an imperfect carding operation required to remove material residues to make the aforementioned through-holes passable. Otherwise, in the case of a tread made, for example, of compressed PU or EVA (where such material residues, due to the molding process, cannot be avoided), these openings would be blind.

When the protective element is placed below the membrane and the latter is sealed directly to the tread, i.e. without the aforementioned sealing element, the protective element has smaller dimensions than the membrane, being obtained for example with a negative offset of 4-6 mm with respect to the membrane template so as not to obstruct the seal.

As regards cavity 120 located on midsole 115, it must be said that it has practically the same template as cavity 113 located on tread 104.

The sole structure 100 may also comprise a breathable element or a layer of breathable material, preferably water-repellent, arranged in correspondence with the second breathable portion 118 and possibly housed in the cavity 120 of the midsole, above or below the through-openings 112a, depending on the position of the cavity 120: arranged on the upper or lower surface of the midsole. It should be added that the cavity 120 may be completely through-opening and completely filled by the aforementioned breathable element or layer of breathable material. In the latter case, in practice it is like having a single through-opening filled with the breathable element or layer of breathable material.

The breathable element or layer of breathable material is shaped according to the cavity template 120 and can be made, for example, of three-dimensional fabric.

The aforementioned breathable element or layer of breathable material at the midsole contributes to further lightening the sole structure while ensuring the flow of sweat in the vapor phase coming from the through-openings 112a of the midsole 115 towards the membrane 110, and from there out towards the external environment through the through-openings 112 in the tread 104.

Also in this embodiment, in accordance with the invention, the evacuation of sweat in the vapor phase occurs far from the area of greatest sweating and maximum flexion of the foot, thanks to the combined action of the ventilation channels 108 of the midsole and the through openings 112a and 112 provided on the midsole 115 and on the tread 104 respectively.

As regards the aforementioned ventilation channels, it should be added that as an alternative to what is reported above, they can have a curvilinear shape that mainly affects the areas most affected by the rolling motion, in particular the portion of the forefoot closest to the outside of the foot, as illustrated in Fig. 7c which shows a left midsole 115, which is a shock-absorbing element, equipped with ventilation channels 108a with a convexity facing the outside of the foot. This design allows for better exploitation of the compression resulting from the rolling motion because it follows its shape more faithfully.

For the embodiments described with reference to figures 5, 6, 7a, 7b and 7c, unless otherwise specified, what was previously reported for the sole structure 1 with the relative variants described with reference to figures 2-4 applies.

With reference to figures 8a and 8b, a further embodiment of the present invention is now described according to two different configurations.

In detail, the examples in figures 8a and 8b schematically illustrate a particular of the present invention, namely a midsole 225 of a sole structure similar to the sole structure 100 described with reference to the example in figures 5, 6, 7a, 7b and 7c to which reference is made, and from which it essentially differs in that it comprises a membrane 210 connected to the midsole 225, in correspondence with a sealing area 209, rather than to the tread, the latter not being illustrated in the example in figures 8a and 8b.

The 225 midsole is therefore intended to be attached to a tread that does not have ventilation channels and does not have a sealing area, while it does have a second breathable portion.

In practice, in the embodiment of the example in figures 8a and 8b, the functional area with its breathable portion (first breathable portion) of the sole structure is arranged in correspondence with the midsole and not with the tread as occurs in the embodiments described previously.

In detail, the midsole 225 comprises an upper surface 226, a lower surface 227 intended to be coupled to the upper surface of the aforementioned tread and the aforementioned breathable portion 207 suitable for the passage of water vapour and extending from the upper surface 226 to the lower surface 227.

Furthermore, the midsole 225 has ventilation channels 208 arranged on its upper surface 226, which are in fluid communication with the breathable portion 207 which, preferably, is equipped with through openings 212a.

In accordance with the invention, the aforementioned breathable portion of the midsole (first breathable portion) and the aforementioned breathable portion of the tread (second breathable portion) substantially overlap each other, in particular at the midfoot, although the possibility of providing them at the rearfoot or between the midfoot and the rearfoot or in the forefoot outside the maximum flexion zone is not excluded.

In the example of Figure 8a, the sealing area 209 to which the membrane 210 is sealed is arranged on the upper surface 226 of the midsole. Furthermore, on the upper surface 226 there may be a cavity 213 in which the membrane 210 is housed.

Alternatively, as shown in the example of figure 8b, the membrane 210 can be sealed on the lower surface 227 of the midsole 225 on which the sealing area 209 is also arranged and on which there can be a cavity 213 that accommodates the membrane 210.

Bearing in mind what has been reported above, it is noted that, in particular with reference to the example in figure 8a, depending on the type of seal, the sealing area 209 can be provided external to the cavity 213 or internal to the cavity 213. If the membrane is sealed directly to the midsole and internally to the cavity, then the seal is created, for example, using glue at least along an external band of the cavity between approximately 4 mm and approximately 6 mm wide. If the membrane is sealed to the midsole indirectly through a sealing element of the type considered previously, then the latter is placed astride the membrane and the sealing area, and in correspondence with the latter, the sealing element is joined to form a seal to the midsole.

With reference to the example in figure 8b, it should be noted that the membrane is practically always sealed in correspondence with a sealing area contained within the cavity. In this case, the membrane is always sealed directly to the midsole without the need for a sealing element.

Similarly to what is reported for the previous embodiments to which reference is made, a breathable element or a layer of breathable material, not illustrated in the examples in Figures 8a and 8b, can be positioned below or above the membrane, depending on the position of the membrane, for all or part of the thickness of the midsole, taking care to maintain the sealing area for the membrane. This means that the template of the aforementioned breathable element or layer of breathable material is smaller than the template of the membrane, being in practice obtained as a negative offset of a value between 4 mm and 10 mm from the latter.

The aforementioned breathable element or layer of breathable material is advantageous because it further reduces the weight of the current sole structure.

In general, the use of the aforementioned breathable element or layer of breathable material is also advantageous because it allows the use of materials characterized not only by high breathability, but also by elasticity (i.e., the ability of a material to reversibly deform following an impact) and/or resilience (i.e., the ability of a material to absorb the energy resulting from stress, typically an impact) different from those of the midsole material. Since the membrane can be positioned not only in the midfoot but also in the rearfoot, the use of a breathable element or layer of breathable material made of particularly elastic material can increase the elastic response of the sole structure, thus returning part of the stress experienced as upward thrust, making walking less tiring.

For the embodiments of figures 8a and 8b, unless otherwise specified, the same applies as previously reported for the sole structures 1 and 100, with relative variants, illustrated with reference to the respective figures to whose description reference is made.

With reference to figure 9, a further embodiment of the present invention is now described.

In detail, the example in figure 9 illustrates a sole structure 300 similar to the sole structure 100 described with reference to the example in figures 5, 6, 7a, 7b and 7c to which reference is made, and from which it differs essentially in that the breathable portion of the functional area provided on the tread (first breathable portion) and the breathable portion of the midsole (second breathable portion) are not superimposed on each other, and in that they include ventilation channels both on the upper surface of the midsole and on the lower surface of the midsole.

The sole structure 300 comprises a midsole 325 connected to a tread 304 which does not have ventilation channels while it has a sealing area 309 which surrounds a breathable portion 318 (first breathable portion) preferably comprising through openings 312, to which a membrane 310 arranged in a cavity 313 is sealed.

In the example of figure 9, the sealing area 309 is inside the cavity 313, however it is also possible to provide a sealing area outside the cavity and surrounding the latter if the aforementioned membrane is sealed to the tread through a sealing element similar to the one previously described.

In particular, the midsole 325 comprises an upper surface 326 and a lower surface 327 coupled to the upper surface of the tread 304, on which ventilation channels 308 are present, and a breathable portion 318a (second breathable portion) suitable for the passage of water vapor and extending from the upper surface 326 to the lower surface 327 of the midsole, wherein the ventilation channels 308 comprise a first series of channels 308a arranged on the upper surface 326 of the midsole and a second series of channels 308b arranged on the lower surface 327 of the midsole, wherein the channels of the aforementioned first series and of the aforementioned second series are in fluid communication with the second breathable portion 318a of the midsole 325, which is preferably provided with through openings 312a.

In particular, the aforementioned ventilation channels flow into the through openings 312a.

It should be added that the channels 308a of the first series extend from the second breathable portion 318a to the forefoot and the channels 318b of the second series extend from the second breathable portion 318a to the rearfoot.

As mentioned above, the breathable portion 318 of the tread and the breathable portion 318a of the midsole do not overlap, and in particular, the first is located at the rear foot and the second at the mid foot.

Each channel 308b of the aforementioned second series flows, at the end opposite to that which flows into the corresponding through-opening 312a, into the breathable portion 318 of the tread 304. In this way, the sweat in the vapor phase produced mostly at the forefoot reaches the channels 308a of the first series of ventilation channels, passes through the through-openings 312a to reach the channels 308b of the second series of ventilation channels, and from here reaches the openings 312 provided on the tread 304 (after having passed through the membrane 310) from which it reaches the external environment.

This construction is advantageous because it allows for greater freedom of design, in particular allowing the through-holes provided on the tread for the release of vapor-phase sweat to be placed at the rear foot, where the surface area available for transpiration may in some cases be larger than that available at the midfoot, and the use of components in the rear foot area of the midsole, such as fluid-filled pads, luminous devices, sensors, or the like, which would otherwise prevent the aforementioned through-holes from being placed at the rear foot.

With regard to the aforementioned ventilation channels, it should be added that they can be substantially longitudinal as illustrated in the example in figure 9. Alternatively, the channels 308a of the first series of channels can have a convexity facing the external portion of the foot, similarly to what is illustrated in the example in figure 7c, and/or the channels 308b of the second series of channels can have a convexity facing the outside of the foot as in the example in figure 10, so as to follow the rolling motion more faithfully, maximizing at almost every point the compression acting on the sweat in the vapor phase present inside the ventilation channels themselves.

For the embodiments illustrated with reference to figures 9 and 10, unless otherwise specified, the same applies as for the sole structures described previously, with relative variants, to whose description reference is made.

With reference to figure 11, a further embodiment of the present invention is now described.

In detail, the example in figure 11 schematically illustrates a sole structure 400 similar to the sole structure described with reference to the example in figures 8a and 8b to which reference is made, and from which it differs essentially in that the tread does not have a breathable portion.

The sole structure 400 comprises a midsole 425 connected to a tread 404, in which the tread has neither ventilation channels nor a breathable portion, while the midsole 425, which comprises an upper surface 426, a lower surface 427 coupled to the upper surface 405 of the tread, and a lateral edge 450 extending between the lower surface 427 and the upper surface 426, is equipped with a breathable portion 407 comprised between the upper surface 426 and the lower surface 427.

The sole structure 400 also comprises ventilation channels 408 arranged on the upper surface 426 of the midsole, which are in fluid communication with the breathable portion 407, which, preferably, is provided with through openings 412.

Therefore, in this embodiment, the relevant sole structure comprises a functional area comprising the aforementioned breathable portion 407 suitable for the passage of water vapour, a membrane 410 which is impermeable to water and permeable to water vapour and a sealing area 409 which surrounds the breathable portion 407 and to which the membrane 410 is sealed in a waterproof manner.

In the example of figure 11, the sealing area 409 to which the membrane 410 is sealed is arranged on the upper surface 426 of the midsole and surrounds a cavity 413 in correspondence with which the through openings 412 are arranged.

In accordance with the invention, the sole structure 400 is further provided with one or more passages 460, in the example of figure 11 three passages, which extend transversely on the lower surface 427 of the midsole 425, from the breathable portion 407 to the lateral edge 450.

For the embodiment shown in figure 11, unless otherwise specified, the same applies as previously reported for the sole structures illustrated with reference to figures 8a and 8b, with relative variants, to whose description reference is made.

The advantages of the present invention, which have become evident during the description above, can be summarized by noting that a waterproof and breathable sole structure is provided, which is particularly resistant and long-lasting and, therefore, capable of avoiding breakage following repeated bending cycles.

Furthermore, this sole structure advantageously guarantees a high level of comfort while walking.

Furthermore, advantageously, this sole structure can be produced at a low cost.

The sole structure according to the present invention is therefore economical and reliable.

This is achieved by moving at least the breathable portion associated with the waterproof and breathable membrane away from the so-called maximum flex zone of the sole structure, where the foot's sweat glands are also present. This also facilitates the flow of sweat in the vapor phase towards the breathable portion of the tread and, where appropriate, the midsole, where it can be expelled to the outside of the shoe.

In this regard, it should be remembered that the purpose of the invention is to preserve the functionality of the aforementioned functional area for a long time to prevent the entry of water from the outside into the footwear comprising the present sole structure. Recalling that by construction, the outline of the aforementioned sealing area of the tread or midsole contains the outline of the aforementioned breathable portion of the tread or midsole, and that the membrane extends both into the breathable portion and into the sealing area, it should be emphasized that the aforementioned functionality can be preserved even in the event of a rupture of the membrane in the sealing area of the tread or midsole, since in this case the waterproofing would still be guaranteed by the presence of the seal. Therefore, in accordance with the invention, it is sufficient for the aforementioned breathable portion of the functional area to be external to the maximum flexion area, while preferably the sealing area and the entire membrane are also external to the maximum flexion area.

To the present invention, in the embodiments illustrated and described, in order to satisfy contingent and specific needs, a person skilled in the art may make numerous variations and modifications, all of which however fall within the scope of protection of the invention as defined by the following claims.

Claims (17)

1. Waterproof and breathable sole structure having an internal side (2) intended to face the inside of a shoe and an external side (3) intended to face the environment outside the shoe, wherein said sole structure (1) comprises: a tread (4) having an upper surface (5) on the side of said inner side (2) and a lower surface (6) on the side of said outer side (3), one or more ventilation channels (8), a functional area comprising its own breathable portion suitable for the passage of water vapour, a membrane (10) impermeable to water and permeable to water vapour and a sealing area (9) surrounding said breathable portion to which said membrane is sealed in an impermeable manner, characterized by the fact that said one or more ventilation channels (8) are capable of directing water vapour towards the surface of said membrane facing said internal side and by the fact that said breathable portion of said functional area is entirely located externally to a portion of the forefoot corresponding to an area of maximum flexion. 2. Sole structure according to claim 1, wherein said membrane (10) is entirely located externally to said maximum flexion zone and/or wherein said sealing zone (9) is entirely located externally to said maximum flexion zone. 3. Sole structure according to claim 1 or 2, wherein said sealing area (9) is substantially flat, wherein preferably said sealing area is essentially smooth. 4. Sole structure according to any of the preceding claims, wherein said functional area is provided with a cavity (13) in which said membrane (10) is housed. 5. Sole structure according to any of the preceding claims, comprising a breathable element or a layer of breathable material (121), preferably water-repellent, arranged in correspondence with said membrane, above or below it and/or a layer of material equipped with channels facing, in use, towards the ground, arranged above said membrane. 6. Sole structure according to any of the preceding claims, wherein said breathable portion is included between said upper surface (5) and said lower surface (6) of said tread, wherein preferably said breathable portion is arranged at the midfoot or at the forefoot anteriorly to said maximum flexion zone. 7. The sole structure of claim 6, comprising a second functional zone arranged on said tread and comprising its own breathable portion suitable for the passage of water vapor, a second sealing zone surrounding said breathable portion, and a second waterproof and water vapor permeable membrane sealed in an impermeable manner to said second sealing zone, wherein said breathable portion of said second functional zone is entirely located externally to said maximum flexion zone, wherein preferably said second sealing zone is entirely located externally to said maximum flexion zone and/or wherein said second membrane is entirely located externally to said maximum flexion zone. 8. Sole structure according to claim 6 or 7, wherein said one or more ventilation channels (8) are arranged on said upper surface (5) of said tread (4) and are in fluid communication with said functional zone and possibly with said second functional zone. 9. Sole structure according to claim 6, comprising a midsole (115) having an upper surface (116), a lower surface (117) coupled to said upper surface (105) of said tread (104) and a second breathable portion (118) suitable for the passage of water vapour and included between said upper surface (116) and said lower surface (117) of said midsole (115), wherein said one or more ventilation channels (108) are arranged on said upper surface (116) of said midsole (115) and are in fluid communication with said second breathable portion (118), and wherein said breathable portion (107) and said second breathable portion (118) are substantially superimposed on each other. 10. Sole structure according to claim 9, comprising a breathable element or a layer of breathable material (121), preferably water-repellent, arranged in correspondence with said second breathable portion (118). 11. A sole structure according to any of claims 1-5, comprising a midsole (225) having an upper surface (226) and a lower surface (227) coupled to said upper surface of said tread, wherein said breathable portion (207) of said functional zone is comprised between said upper surface (226) and said lower surface (227) of said midsole (225), said sole structure comprising a second breathable portion comprised between said upper surface (5) and said lower surface (6) of said tread, wherein said one or more ventilation channels (208) are arranged on said upper surface (226) of said midsole (225) and are in fluid communication with said breathable portion (207), wherein said breathable portion (207) and said second breathable portion are substantially overlapped with each other. 12. Sole structure (300) according to claim 6, comprising a midsole (325) having an upper surface (326), a lower surface (327) coupled to said upper surface of said tread (304) and a second breathable portion (318a) suitable for the passage of water vapour and comprised between said upper surface (326) and said lower surface (327) of said midsole (325), wherein said one or more ventilation channels (308) comprise a first set including one or more channels (308a) arranged on said upper surface (326) of said midsole and a second set including one or more channels (308b) arranged on said lower surface (327) of said midsole, wherein the channels (308a, 308b) of said first series and of said second series are in fluid communication with said second breathable portion (318a), wherein said breathable portion (318) and said second breathable portion (318a) are staggered with respect to each other and not overlapped. 13. Sole structure (300) according to claim 12, wherein said breathable portion (318) of said functional zone and said second breathable portion (318a) are extended at the rear foot and the midfoot respectively, wherein preferably said one or more channels (308a) of said first series are extended from said second breathable portion (318a) to the forefoot and said one or more channels (308b) of said second series are extended from said second breathable portion (318a) to the rear foot. 14. A sole structure according to any of claims 1-5, comprising a midsole (425) having an upper surface (426), a lower surface (427) coupled to said upper surface (405) of said tread (404) and a lateral edge (450) comprised between said lower surface (427) and said upper surface (426), wherein said breathable portion (407) of said functional zone is comprised between said upper surface (426) and said lower surface (427) of said midsole (425), wherein said one or more ventilation channels (408) are arranged on said upper surface (426) of said midsole and are in fluid communication with said breathable portion (407), and wherein said sole structure is provided with one or more ventilation channels (408). transverse passages (460) extending on said lower surface (427) of said midsole from said breathable portion (407) to said lateral edge (450). 15. Sole structure according to any of the preceding claims, wherein said one or more ventilation channels (8) have a width between 2 mm and 10 mm, wherein preferably said one or more ventilation channels (8) have a depth between 1 mm and 5 mm. 16. Sole structure according to any of the preceding claims, wherein said one or more ventilation channels (8) have a bottom at the level of said sealing area (9). 17. Sole structure according to any of the preceding claims, wherein said zone of maximum flexion is delimited by construction lines s, t.