The subject of the invention is a perforated water-resistant coating for footwear protection that provides protection against penetration of water into the interior of footwear by a water-repellent layer, which layer is mechanically or otherwise treated in a way that the water-repellent layer is perforated with a series of tiny pores. The invention belongs to class A43B23/06 of the international patent classification.
A technical problem solved by the invention is protection against penetration of water in the interior of footwear and simultaneously transport of water vapour from the interior of footwear into the ambient.
It is a known fact that a human body needs to be protected against too low temperatures and especially against the influences of atmospherilia like rain and snow. A foot therefore needs protection by footwear that is impervious to water. A disadvantage of such known solution lies in that it prevents a foot from breathing and therefore causes an uneasy feeling and excess sweating. There are various solutions to the described problem that include a variety of semi-permeable membranes that prevent water from penetrating into footwear interior and provide for a limited flow of air and water vapour. A drawback of these solutions lies in the fact that an external protective layer is needed for protection against mechanical damage, and this layer is not impermeable and usually in the form of fabric or leather. Both fabric and leather absorb water thus increasing in mass, which requires more effort in the use of footwear and contributes to impaired heat insulation. Due to the rough surface of fabric the quotient of friction between fabric and snow is higher than that exerted between snow and entirely smooth surface, like that of a water-repellent material for instance. When walking in nature in any time of the year, we are often exposed to the influence of water or snow that covers a large surface of a shoe. A smooth surface provides for a quicker sliding of snow or water off a shoe and a shoe material is thus exposed to water for a shorter time period. A shorter time period during which a shoe is covered with water or snow means less possibility of penetration of water into footwear and more time for footwear to breathe.
The invention will now be described in more detail based on an embodiment and figures representing in:
The structural solution of the invention provides a possibility to manufacture footwear having a water-repellent coating 3 from a perforated material in the shape of tiny pores arranged over the surface of the material, said pores having a considerably smaller diameter than the total material thickness. The upper part 1 is manufactured from a perforated material consisting of two layers, the external one being a water-repellent layer 5 and smooth on its surface and the internal being a reinforcing layer 6 manufactured from a woven or unwoven fabric and the two layers are inseparably joined and treated in a way that tiny pores 4 are manufactured through both materials prior to use, said pores having a smaller diameter than the thickness of the external layer and are small enough to resist water penetration due to capillary pressure and yet large enough for the footwear to breathe therethrough. In special cases only a part 7 of said upper part 1 may be manufactured from a water-repellent material 7.
Said perforated material 3 consists of at least two layers and is composed of the external smooth and water-repellent layer 5 and the internal reinforcing layer 6, which is either woven or unwoven, wherein said layers are joined in a way that the external layer 5 remains smooth on its external side. The perforation 3 is effected by tiny pores, the diameter of which does not exceed the thickness of the material of the external smooth layer, the diameter preferably being less than 0.1 mm and the pores are arranged mutually close enough to provide for a sufficient breathing of the material, preferably more than 10 pores per cm2.
The structural solution of footwear manufacturing described above is hereinafter extended to footwear for ski running, wherein the topmost material is functionally or rather technologically manufactured in a way to prevent water and moisture from entering from the external side of the shoe into shoe interior on the one hand and on the other diverts moisture from foot sweating from the shoe interior towards the exterior, i.e. away from the foot.
The upper shoe material here disclosed does not form part of the invention. It consists of several layers. The outermost layer 1' is perforated, i.e. has pores of an optional diameter over its surface that are optionally arranged.
The outermost layer 1' may be manufactured in the shape of a mesh, so that it consists of, is composed of or is woven of filaments of an adequate thickness of an optional synthetic material, said filaments being mutually interwoven in an optional way and form the perforated surface of the material. The outermost layer 1' may also be made of a synthetic material, like PVC, PU, etc. by the use of technology »casting onto carrier material, where the surface of the material is mechanically perforated. Among others, the upper layer is water impermeable, smooth on its external surface and water repellent.
A next layer 2' immediately following the external upper layer is of a material that breathes, i.e. a breathable membrane. The membrane is a material, the fundamental functional capability of is determined by two features. The first is resistance of the membrane to the penetration of water and moisture from the external side towards the interior, i.e. the pressure that the membrane can take when water and moisture enter from the external side.
The second important feature is the capability of the membrane to transport water vapour from the interior of the shoe outwards (membrane permeability / permeability quotient in milligrams per square centimetre per hour), which is indicative of a certain quantity of water vapour that the membrane is capable of permeating within a certain time period.
A layer 3' laid onto the upper two layers is a protective fabric / carrying mesh (i.e. tricot), the function of which is protection of the membrane against mechanical influences or damages.
The structure of the material or laminate as described hereinbefore consists of three basic layers. Said laminate may, however, also consist of more than three basic layers, if need may be from a functional point of view. Further layers apart from the three basic ones may be added to the basic laminate in order to improve the load capacity of same, in order to improve thermo-insulation of the laminate or to improve distribution of moisture within a shoe with the purpose of getting the largest surface possible, through which moisture would evaporate through the permeable membrane from the shoe interior outwards.
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