Patent Publication Number: US-6655048-B2

Title: Breathable and waterproof sole for shoes

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a breathable and waterproof sole for shoes. 
     Shoes having rubber soles which can ensure particular practicality and comfort but do not allow the foot to breathe at all are already known and commercially available. 
     Rubber soles with perforations in the tread and membranes superimposed on the perforated area and sealed in the peripheral regions have also been known for a few years. 
     These soles allow correct breathing in addition to an effective exchange of heat and water vapor between the environment inside the shoe and the outside environment while ensuring the necessary impermeableness to external moisture and water. 
     Other constructive solutions provide box-like rubber soles with perforations at the lateral edges which are internally obstructed by waterproof and breathable membranes which in this case also are joined peripherally so as to form a seal. 
     These perforated soles, provided with waterproof and breathable membranes, have certainly constituted considerable improvements with respect to what was previously available. 
     Nonetheless, there are still some practical drawbacks mainly due to the area occupied by the perforations, which though being sufficient has not yet reached its optimum extension. 
     On the other hand, in the first case the number of perforations formed in the tread and the diameter of said perforations must be kept small in order to prevent pointed foreign matter entering through the perforations from penetrating until they damage or pierce the membrane. 
     Such membrane is in fact continuously subjected to the compressive action of the foot, so that even a body which is not particularly sharp might easily cause damage. 
     Soles are also known which internally comprise channels and systems for pumping air from the inside of the shoe to the outside by means of one-way valves. 
     Pumping is actuated by the compression of the foot during walking. 
     Accordingly, in this case the operation is merely mechanical and a stream of inflowing cold air is produced which in winter periods can be particularly unpleasant, since it causes rapid chilling of the feet, causing discomfort to the user. 
     Moreover, the execution of the pumping devices integrated in the soles is expensive and complicated. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to provide a breathable and waterproof sole for shoes which allows an optimum exchange of heat and water vapor with the outside, which ensures at all times an optimum internal microclimate as a function of the external microclimate, solving the abovementioned drawbacks suffered by known types. 
     Within this aim, an object of the present invention is to provide a sole in which the integrity of the breathable membrane is protected effectively while allowing adequate air circulation. 
     Another object is to provide a sole which is able to keep the inside of the shoe dry even in the presence of condensation of the water vapor produced by perspiration due to excessive external humidity. 
     Another object is to provide a sole which minimizes the problem of deposition of dirty material on the breathable membrane. 
     Another object is to provide a sole which can be easily adapted to shoes of various kinds both for daily and sports use. 
     Another object is to provide a sole whose cost is comparable to the costs of known soles. 
     Another object is to provide a sole which can be manufactured with technologies and equipment which are already known in the field. 
     This aim and these and other objects which will become better apparent hereinafter are achieved by a breathable and waterproof sole for shoes, characterized in that it comprises, at least along part of its extension: 
     a lower waterproof component, which constitutes the tread; 
     an upper component, with a supporting structure which has interconnected chambers with outlets at least on the upper and edge surfaces; 
     a membrane which is impermeable to water and vapor-permeable and externally surrounds at least the outward-facing regions of said upper component; 
     said lower and upper components and said membrane being joined so as to form a seal at least in the regions where water infiltration is possible. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further characteristics and advantages of the invention will become better apparent from the detailed description of some embodiments thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein: 
     FIG. 1 is a partially sectional view, in phantom lines, of a shoe provided with a sole according to the invention; 
     FIG. 2 is a cross-sectional view, taken along a transverse plane, of the sole of the shoe of FIG. 1; 
     FIG. 3 is a partially exploded enlarged-scale perspective view of a detail of the sole of FIG. 2; 
     FIGS. 4 to  6  are views of shoes provided with respective embodiments of the sole according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIGS. 1 to  3 , a breathable and waterproof sole for shoes according to the invention is generally designated by the reference numeral  10  and comprises a lower component  11 , which constitutes the wear tread, in this case made of waterproof material, for example a polymer such as polyurethane, rubber, PVC or the like. 
     As an alternative, it is possible to use breathable materials, such as leather, waterproofed for example by means of an upper membrane which is joined perimetrically so as to form a seal, of the type which is impermeable to water and vapor-permeable. 
     The sole  10  further comprises an upper component  12  with a supporting structure, which has interconnected chambers with outlets at least on the upper and edge surfaces. 
     In the particular embodiment shown in the figures, the upper component  12  has a lattice-like structure made of plastics by molding, with chambers  13  which are interconnected by means of openings  14  provided in the partitions  15 . 
     As shown in FIG. 1, a plurality of chambers  13  faces the lateral edge  16  and the upper supporting surface, on which in this case there is an insole  17  with through holes  18 . 
     The insole  17  can be conveniently made of leather or other suitable breathable or perforated material. 
     As an alternative to what has been described, the upper component  12  can be formed for example by means of a block made of sponge-like open-cell material which is capable of bearing the weight of the user and of allowing the free passage of perspiration. 
     For this purpose it is possible to provide materials such as latex foams or polyurethane foams of the open-cell type. 
     It can also be convenient to integrate in the upper component  12  conventional impact cushioning systems, for example pads filled with air, gel, etcetera. 
     The sole  10  further comprises a membrane  19  made of a material which is impermeable to water and permeable to vapor (such as the ones commercially available and commonly known by the trade-name Gore-Tex). 
     The membrane  19 , which can also be coupled to a light supporting fabric, not shown in the figures, wraps around the edge  16  of the upper component  12  at least in the regions that face outward and is joined thereto by perimetric gluing, taking care not to obstruct the chambers  13  with the adhesive. 
     It is therefore possible to apply adhesive to the edges of the partitions  15  or to provide the membrane  19  with such an extension that it can be turned over, as shown in FIG. 2, around the edge  16  and thus be glued in an upward region and in a downward region on the perimetric parts of the upper component  12 . 
     The two ends of the membrane  19  can be mutually joined at one of the partitions  15  (as shown in FIG. 1) and then glued thereto so as to form a seal, or can be applied as a tape with heat or adhesives so as to provide a waterproof sealing joint. 
     The sole  10  further comprises, in this case, a protective element  20  superimposed on the membrane  19  and constituted for example by a fine-mesh net or by a layer of breathable material which protects the membrane  19  from contacts with blunt objects which can rupture it. 
     The protective element  20  can be applied by spot gluing or by full gluing in the regions of the membrane that are folded back around the edge  16 , so that on the edge  16  there is no adhesive which compromises breathability. 
     As an alternative, the membrane  19 , optionally with its protective element  20 , can be arranged as a mold insert onto which the upper component  12  is overmolded so as to ultimately constitute a sealed monolithic element. 
     It should also be noted that the membrane can be provided so as to make it difficult to pierce, for example by using aramid fibers or other material as a support. 
     The membrane can be made of hydrophilic polymer, and in this case can be integrated in a support which is permeable to water and comprises fibers of materials, which are technologically per se known, as composites. 
     In this case, i.e., if the membrane  19  is capable of withstanding blunt objects thanks to its very structure, the presence of the protective element  20  might not be necessary. 
     The upper component  12  is joined hermetically to the lower component  11  according to known gluing methods, or the complete sole  10  can be manufactured by means of individual or multiple injections and by inserting, as an insert, the membrane  19  (optionally with its protective element  20 ) or the membrane  19  with the already-prepared upper component  12 . 
     It is particularly important to provide a hermetic joint between all the elements in contact in the regions where water infiltration is possible. 
     The upper component  12  acts as a container which is closed at the bottom by the lower component  11  and is open perimetrically with a breathable and waterproof band. 
     The assembly is conveniently assembled to an upper  21  in manners known in the shoemaking field, taking care not to obstruct the passage of vapor from the inside of the shoe toward the chambers  13 . 
     With reference now to FIGS. 4 to  6 , said figures show respective embodiments of the invention, in the first of which the upper component  112  has a smaller extension than the lower component  111  and is extended in particular at the heel region. 
     In this case, appropriately provided channels, not shown in the figure, can be provided in an upward region in the lower component at the forefoot and it is possible to provide holes in the inner sole so that perspiration can pass easily from toe to heel. 
     In FIG. 5, the lower component  211  and the upper component  212  are monolithic so as to form the heel. 
     The sole  10  thus provided is fully impermeable and breathable along the entire edge region of the upper component  12  without thereby reducing the functionality of said sole (impact absorption, flexibility, light weight, et cetera). 
     From the point of view of operation, the foot compresses the upper component  12 , pushing perspiration out of the shoe after the moist air has entered the upper component  12  from the holes of the insole  17 . 
     By using a breathable and waterproof membrane of the type that also allows air to exit from inside, a considerable increase in the exchange of air in said shoe is achieved, which is very useful in products for athletes. 
     The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. 
     All the details may further be replaced with other technically equivalent elements. 
     Thus, for example, the lower component  11  can be conveniently constituted by a perforated lower layer with, in an upward region, a membrane which is breathable and waterproof (with or without a light supporting fabric), joined hermetically thereto in the perimetric regions. 
     The membrane can be conveniently provided in a downward region with a protective layer. 
     This occurs if it is necessary to further increase the possibility of exchange with the outside. 
     In practice, the materials used, so long as they are compatible with the contingent use, as well as the dimensions, may be any according to requirements. 
     The disclosures in Italian Patent Application No. PD2000A000253 from which this application claims priority are incorporated herein by reference.