The present invention refers to the manufacture of waterproof footwear, particularly waterproof and vapour-permeable (breathable) footwear.
Waterproof, vapour-permeable footwear, that is to say footwear able to protect the foot from the entry of water, though allowing regular evaporation of perspiration meet with widespread public favour at present. To obtain the desired characteristic of watertightness and vapour-permeability, a layer or sheet of material impervious to water and pervious to vapour, that is, vapour-permeable, per se known and available on the market, is generally incorporated. The sheet is generally incorporated into the footwear as a lining or part of the lining of the upper. Footwear of this type generally have a vapour-permeable upper and a waterproof sole injection-moulded so as to be joined to the insole and to the upper.
The known footwear are made with one or more seams to join together the upper and the lining and possibly the insole. Problems arise at these seams as far as watertightness is concerned because the stitching forms a break in the continuity of the waterproof, vapour-permeable membrane and water can enter the inside of the footwear through the stitching holes. The problem is particularly serious if the upper is made of leather (as is desirable on other counts) in that the sheet of leather, even if it does not allow direct passage of water through the leather, easily conveys the water impinging thereon by capillarity in the direction in which the sheet extends, up to the edges thereof, from which the water can pass inside the footwear, possibly through the stitching holes.
Attempts have been made to remedy the problem in various ways. European patent EP 0 298 360, for instance, teaches a footwear provided with a lining with a waterproof, vapour-permeable layer and an injection moulded sole, wherein the edge of the upper is positioned at a distance with respect to the edge of the lining; the edge of the upper is stitched to one side of a porous tape, the other side of which is stitched to the lining. During injection moulding the material of the sole passes through the holes in the porous tape and forms a waterproof layer between the stitching involving the upper, which could allow moisture to pass, and the stitching involving the lining, and thus the inside of the footwear.
DE 40 04 674 refers to a footwear comprising an upper, a lining with a waterproof, vapour-permeable membrane, an insole and a sole of plastic material formed integrally at least with the upper and with the insole, where the bottom edge of the upper is joined to one end of a vertical non-porous tape, whose second end is joined to the lining and to the insole.
Said systems have the drawback, however, of being relatively complex and costly.
An object of the present invention is to overcome the problems of the prior art.
Another object is to make a footwear of the type with a waterproof, vapour-permeable lining, in which the outside water cannot pass in any way to the inside of the footwear through the components thereof, and to achieve this with an economically advantageous system that is easy to apply.
The objects have been achieved with a footwear as stated in claim 1 and a method as stated in claim 3.
The invention achieves the above objects, in particular allowing fully waterproof footwear to be made at limited cost.
The invention will be described, by way of a non-restrictive example, with reference to the attached drawings, in which:
With reference to the figures, a shoe or footwear according to the invention is designated as a whole with reference numeral 10 and comprises at least an upper 12, a lining 14, an insole 16, a sole 18 of plastic material formed directly on the other elements, and a non-porous tape 20.
The upper 12 is made of sheet material, of any type suited to the purpose, for example leather, and is cut so as to have its bottom edge 22 ending at a distance, that is more outward, with respect to the edge of the lining, as shown in the figures.
The lining 14 comprises a layer or membrane 24 of waterproof and vapour permeable, or breathable, material and preferably further comprises one or more complementary layers or sheets 26 (only one is illustrated in the figures) with thermal, aesthetic and shock-absorbing functions, as is usual. The bottom edge of the lining 14 is cut so as to be "longer" than the upper, so that it can be turned in along the bottom part of the footwear.
The insole 16 is made of conventional sheet material for insoles, for example needled fabric, and is cut so as to have an outline which defines a smaller area than the entire bottom inside area of the footwear.
The tape or band 20 is made of non-porous material, for example U.A. 014 from Uno Art, and has a layer of heat-reactive or thermo-reacting adhesive (per se known) on one side, precisely the side 21 facing upward, toward the lining, in the figures. The tape 20 is sewn, with a longitudinal margin or edge 28 thereof, to the bottom edge of the upper; said seam is designated by 30 in Figure 4. The seam is of the reversed or rolled type. The other longitudinal edge, 29, of the tape 20 is sewn together with the bottom edge of the lining 14 and the edge of the insole 16. The sewing or seam is preferably of the pinching or chain-stitch Strobel type and is designated by reference numeral 32. The side 21 of the tape in the finished footwear is adherent to a strip of lining near the bottom edge thereof.
The sole 18 is made of waterproof elastomeric material formed directly integral with the upper, the insole and the tape, by means of any per se know forming method, such as injection moulding, extrusion or other.
The foot wear manufacturing method will now be described.
In the first place, the upper 12 and the lining 14 are made or provided, cut so that the bottom peripheral edge of the lining extends a certain distance beyond the peripheral bottom edge of the upper, as well as the non-porous tape or band 20. The upper can be of any known sheet material suited to the use, for example leather. The lining comprises, in a per se known manner, a sheet or membrane of waterproof and vapour-permeable material, designated by 24, and preferably one or more further sheets coupled thereto, to perform other functions, for example to give better thermal insulation or greater comfort, or even for aesthetic purposes. The tape 20 is preferably made of a closely woven fabric of synthetic thread, coated on at least one side with a layer of glue that is heat-activated. The tape is thus non-porous. An adhesive not incorporated into the non-porous tape could also be used.
The bottom edge of the outer upper is joined to the tape by stitching; a rolled seam is preferably used, as denoted by 30 in the figures. The stitching 30 involves only the tape and the upper, not the lining. The side of the tape coated with adhesive faces toward the lining of the footwear. The tape, the lining and the edge of the insole are then joined together by stitching, preferably by a Strobel or chain sewing referenced 32.
The plastic material sole 18 is then hot moulded onto the assembly consisting of the insole, lining, upper and tape, so as to be in contact and engaged with the insole, tape and upper. Hot moulding of the sole causes activation of the adhesive on the tape, which adheres against the opposite surface of the lining, thus forming a peripheral seal against possible entry of moisture along the seam 30, along the entire perimeter of the bottom part of the shoe. Alternatively, the adhesive of the tape could be activated with a separate operation preliminary to forming of the sole.