"Method for the production of breathable waterproof shoes"

DESCRIPTION

The present invention relates to a method for the production of breathable waterproof shoes.

It is known that the comfort of a shoe depends on various factors. On the one hand, it is essential that the shoe should be able to adapt to the shape of the foot and, on the other hand, it is important that it should be able to have water-repellent and breathable properties as well as lightness and flexibility.

Systems for providing breathable waterproof uppers for shoes are known, these consisting, for example, in the use of breathable membranes which ensure on the one hand waterproofing of the upper and on the other hand a certain degree of breathability of the shoe.

In the conventional processes for assembly of this type of shoe, sealing of the bottom part is particularly critical.

The upper, which is assembled with the impermeable and breathable membrane inside, is fitted, open at the bottom, onto the last on which the assembly insole is already mounted. Then the bottom end of the upper is folded over along the outer perimeter of the insole and finally glued onto the latter. During the assembly operation, it is possible that puckering may occur along the bottom outer edge of the upper, preventing the perfect gluing of the upper to the insole. Consequently, the water which is absorbed or is deposited onto the upper, or is present on the ground, may trickle to the bottom of the shoe and, if there is no seal between the upper and insole, may penetrate inside the shoe, such that the shoe is no longer waterproof.

Various technical solutions which attempt to overcome this drawback are known.

For example, in EP 1195100 the bottom part of the shoe is sealed and rendered waterproof by applying onto the outer surface of the assembly insole an adhesive material which is reactivated and then melted by means of heating or exposure to infrared rays. The application of such an adhesive, however, requires the use of dedicated equipment which, in addition to increasing the manufacturing time, also results in an increase in production costs.

In EP 1216627, on the other hand, the bottom part of the shoe is sealed by overinjecting a layer of plastic material which covers the assembly insole and the gluing edge of the upper/membrane assembly. In this case, also, the need to provide special moulds in order to form the said seal results in an increase in the production costs.

In EP 1454548, in order to reduce the folds which form during assembly of the upper with the breathable membrane, the upper is fixed onto the outer perimeter of the assembly insole, while the breathable membrane is passed through a longitudinal slit formed in the assembly insole. The bottom part is sealed by means of overinjection of a plastic material onto the insole. In this case, also, the provision of the slit on the insole, the need to pass the membrane inside this slit, the provision of special moulds and the ensuing moulding operation result in an increase in the production costs and longer manufacturing times.

Finally, in EP 1476038 also, which describes the method for production of a shoe using the "strobel" method", the bottom part of the shoe is sealed and rendered waterproof by applying onto the assembly insole an adhesive waterproof layer. The same comments made in connection with EP 1195100 are also applicable to this document.

Other processes consist in forming an inner shoe with a lining having a membrane which is also closed on the bottom so as to be entirely waterproof. This, however, results in a higher cost of the shoe and greater difficulties during industrial production of the article which result in the shoe being substantially more costly.

The object of the present invention is therefore to overcome the drawbacks of the prior art.

In particular, one object of the present invention is to provide a method which is able to obtain a shoe which is completely waterproof, lightweight, flexible and breathable and which remains as such as over time.

Moreover, another object of the present invention is to provide a method which can be easily implemented on an industrial level.

A further object of the present invention is to provide a method which is able to reduce the manufacturing time and costs required to obtain a breathable waterproof shoe.

These objects and other objects are achieved with a method for the production of impermeable and breathable semi-finished articles according to Claim 1.

In particular, the method according to the present invention, in the preferred embodiment, consists in the manufacture of a semi-finished article which, together with an outsole, forms subsequently the final shoe, said method comprising the following steps:

- forming an assembled piece by combining the upper, the bottom edge of which has been stripped, with an impermeable and breathable membrane, and a lining which also has a stripped bottom edge;

- mounting the assembled piece on an insole so as to obtain the semi-finished article, leaving the outer edge of the membrane to project beyond the edge of the upper, preferably by at least 5 mm;

- abrasive treatment of the bottom of the semi-finished article in order to remove the puckers which have formed on the upper during the assembly operation, making sure not to cause abrasion of the membrane;

- spraying the bottom part of the semi-finished article with a mixture comprising a reactive polymer material, ensuring in particular that the edges projecting from the membrane are perfectly covered by the sprayed material; and

- pressing the bottom part of the sprayed semi-finished article, so as to level the thickness of the layer of polymer material.

The characteristic features and further advantages of the invention will emerge from the description, provided hereinbelow, of a number of examples of embodiment, provided by way of a non-limiting example, with reference to the accompanying drawings in which:

- Figure 1 shows schematically a cross-sectioned side view of a shoe;

- Figure 2 shows, on a larger scale, a detail of the shoe shown in Figure 1 ;

- Figure 3 shows schematically the cross-section along the plane indicated by the line III-III in Figure 1 ;

- Figure 4 shows, on a larger scale, a detail of Figure 3;

- Figure 5 shows schematically a semi-finished article consisting of the upper/membrane/lining assembly and insole mounted on a last;

- Figure 6 illustrates the method of waterproofing the semifinished article according to the invention;

- Figure 7 shows schematically the semi-finished article according to Figure 5 after undergoing the waterproofing method according to the invention;

- Figure 8 illustrates schematically the method for waterproofing a semifinished article, containing breathable inserts, according to the invention;

- Figure 9 shows schematically a cross-sectioned side view of the semi-finished article according to Figure 8 on which the waterproofing process according to the invention is being carried out;

- Figure 10 shows schematically the semi-finished article according to Figure 8 after undergoing the waterproofing method according to the invention;

- Figure 11 shows schematically the cross-section along the plane indicated by the line XI-XI in Figure 10;

- Figure 12 illustrates schematically the method for waterproofing a semifinished article, made using the "strobel" technique, according to the invention;

- Figure 13 shows, on a larger scale, a detail of Figure 12;

- Figure 14 illustrates schematically the method for waterproofing a semifinished article, made using the "strobel" technique, according to the invention;

- Figure 15 shows schematically a shoe manufactured using the so-called "AGO" assembly method; - Figure 16 shows schematically the cross-section along the plane indicated by the line XVI-XVI in Figure 15.

In the description of the method for the production of breathable waterproof shoes which is provided below, the term "shoe" refers to any type of shoe, be it of the low or high type, or a sporting, technical or walking shoe.

With reference to the shoe, assuming a correct use thereof, the term "bottom" refers to the part of the shoe which is relatively closer to the ground, and "top" refers to the part of the shoe which is furthest from the ground.

In the context of the patent below, finally, "spraying" means the use of pulverized (atomized) liquid mixtures.

With reference to Figures 1 and 2, these show in schematic form a shoe, which is denoted overall by the reference number 10 , comprising a semi-finished article 11 and an outsole or tread 20.

The semi-finished article 11 consists of an assembled piece 14 formed in turn by an upper 15 made of breathable material, for example natural leather, an impermeable and breathable membrane 17, which covers the inner surface of the upper 15, and finally a breathable lining 19 of the conventional type.

The semi-finished article 11 is completed by an assembly insole 16 which is made of semi-rigid material, for example pressed cardboard, non-woven fabric, leather and the like, to which insole the bottom edge of the assembled piece 14 is fixed.

Considering now the method of the invention for the production of an impermeable and breathable semi-finished article, it comprises, as defined above, the series of steps described below.

The assembled piece 14 is formed by assembling the upper 15, the bottom edge of which has been stripped, with a breathable and impermeable membrane 17 and with a lining 19 which also has a stripped bottom edge.

The assembled piece 14 is mounted on an assembly insole 16 so as to obtain the semi-finished article 11, leaving the outer edge of the membrane to project beyond the edge of the upper 15, preferably by at least 5 mm.

The bottom of the semi-finished article 11 is subject to an abrasive treatment (operation known as "roughing" in shoe manufacturing technology) in order to remove the puckers which have formed on the assembled piece 14 during the assembly operation, making sure not to cause abrasion of the membrane 17. The bottom part of the semifinished article 11 is sprayed with a mixture comprising a reactive polymer material, ensuring in particular that the projecting edges of the membrane 17 are perfectly covered by the sprayed material.

Finally the bottom part of the sprayed semi-finished article 11 is pressed, so as to level the thickness of the layer of polymer material.

In order to understand better the particular features and the advantages of the present invention, in connection with Figures 15 and 16 the traditional method for the production of breathable waterproof shoes will be described, with particular reference to the so-called "AGO" assembly method.

Firstly an insole 16 is fixed to the last 12. The insole 16 is made of semi-rigid material, such as pressed cardboard, non-woven fabrics, leather or the like.

Then the last 12 is lined with an upper/lining/breathable membrane 14 previously assembled as described above. This upper/lining/membrane assembly 14 is breathable since it is made using breathable external materials (for example natural leather) and assembled internally with an impermeable and breathable lining.

As regards the step for formation of the assembled piece 14, assembly of the upper, membrane and lining must be performed using known methods able to ensure the integrity of the membrane and thus ensure that the upper itself is impermeable and breathable.

During the assembly step, after the assembled piece 14 has been prepared and fitted onto the last 12, the bottom part of said assembled piece 14 is folded around the bottom edge of the last 12 and glued onto the insole 16 along the entire outer perimeter thereof along a section 18, which is preferably about 2 cm wide; this section 18 may be defined as being the gluing edge which in fact joins together the insole 16 to the assembled piece 14.

The semi- finished article 11 which is obtained completely encloses the last 12, except for the top opening through which, once the form 12 has been removed, the user's foot is inserted.

After performing roughing of the assembled piece 14 along the pre-stripped gluing edge, making sure not to cause abrasion of the membrane, the outsole 20 is applied using known adhesives for soles, which are spread over the entire surface to be covered by the outsole.

Depending on the material from which the outsole 20 is made, a different category of adhesives is used.

Roughing of the assembled piece 14 along the gluing edge 18 results in better adhesion between the assembled piece 14 and the outsole 20 and ensures uniformity in the thicknesses along the bottom of the semi-finished article 11.

The impermeability of the shoe 10 thus obtained depends solely on the quality of the adhesives and their capacity to act, also over time, as sealants for the joint between outsole 20 and assembled piece 14 and between assembled piece 14 and insole 16.

Figures to 1 to 14 illustrate the characteristic steps of the method according to the invention. The membrane 17 must have a length such that, when folded around the insole 16, it projects from the edge of the upper 15, preferably by at least 5 millimetres. The membrane 17 is thus not covered by the upper 15 along a strip which preferably has a width of at least 5 mm.

After lasting the assembled piece 14 (upper 15, membrane 17 and lining 19) onto the last 12, fixing it to the insole 16 (Figure 5), performing roughing of the upper 15 along the section 18 which corresponds to the gluing edge and before applying the outsole 20, sealing of the bottom of the semi-finished article 11 is performed (Figure 6).

This sealing operation is performed by means spraying, using known devices 24, for example the spraying device described in patent application No. TV2008A000127, of a mixture comprising a reactive polymer material, for example bi-component or multi- component polyurethane or multi-component polyurethane resins.

These materials are water-repellent and are characterized by a high degree of fluidity. Moreover they crosslink in the cold state fairly rapidly.

In Figures 6 and 8, Z indicates, in schematic form, the jet of sprayed mixture produced by the device 24.

In order to facilitate spraying, the semi-finished article 11 is overturned so that the bottom part of the semi-finished article 11 is directed upwards.

A mask or template 22 is positioned at a few centimetres from the bottom, either resting on it or resting along the edges of the semi-finished article 11. A single -piece template or a template consisting of two or more half -rings (Figure 6) may be used.

The template 22 defines the zone of the semi-finished article 11 on which the sealing operation must be carried out. It in fact covers and consequently shields against the sprayed jet Z the parts of the semi-finished article 11 which must not be covered with the layer of polymer material. The template 22 also prevents any misdirected material from being able to strike the outer part of the upper 15, soiling it.

The bottom part of the semi-finished article 11 is sealed by means of spraying, making sure in particular that the projecting edges of the membrane 17 and the area whose perimeter is defined between the said edges are perfectly covered by the sprayed material S. In some cases it may be convenient to seal also the side part of the semi-finished article 11 , if it has to be subsequently covered by the outsole 20 or some other part.

Spraying is performed while keeping the device preferably at a distance of about 10 cm from the bottom of the semi-finished article 11.

The operator may hold in one hand the semi-finished article 11 to be sealed, on which the template 22 has been mounted beforehand, and with the other hand move the device 24. The relative movement of the device 24 and the semi-finished article 11 is schematically indicated by the arrows Yl, Y2 in Figures 6 and 8. The arrows Yl, Y2, for the sake of convenience, simulate the movement performed along the longitudinal axis of the semi-finished article 11 (from the toe towards the heel and vice versa), but the spraying step may also be performed along the transverse axis of the semi-finished article 11 (from the inner side towards the outer side and vice versa) and along the vertical axis when sealing of part of the edge of the upper 15 is also required.

According to a further embodiment it may be envisaged using a "shoe assembly column" (not shown in the accompanying figures) of the type used for removing the lasts from shoes. In this case, the shoe assembly column allows fixing in position of the semifinished article 11 and the template 22 with the bottom directed upwards, so that the operator, who has one hand free, is able to perform spraying more easily.

By pressing the bottom of the semi-finished article 11 against a counter-template (not shown) the thicknesses of the material S sprayed are rendered uniform.

During this step the material S is still in the fluid state and consequently the pressing action against the counter-template allows the material S to be distributed uniformly over the entire bottom of the semi-finished article 11. The material S may also penetrate inside any interstices present in the zones where the upper 15 and insole 16 overlap, ensuring a perfect seal.

The fluidity of the material S also ensures that small spaces or holes, which may be not covered with glue during the previous operations, may be sealed.

The subsequent conversion of the sprayed material S into foam results, on the one hand, in an increase in volume, and on the other hand further helps close any interstice.

The layer of material S thus sprayed and pressed adheres perfectly to the bottom of the semi- finished article 11 , ensuring that the bottom is impermeable.

Any water, in fact, may penetrate into the vicnity of the layer of material S, but may not penetrate inside the shoe 10.

Impermeability of the shoe 10 is therefore ensured, irrespective as to the quality and the type of bond between semi-finished article 11 and outsole 20.

Moreover, the layer of material S, owing to the resilient properties of the reactive polymers used, ensures flexibility of the shoe 10.

It is preferable for the thickness of the layer S to be kept in the region of a few millimetres.

In the case of particular requirements, however, with the use of suitable mixtures, it is possible to obtain a greater degree of expansion. In this case, the layer S could ensure waterproofing of the bottom of the semi-finished article 11 and at the same perform a cushioning function.

After performing this pressing operation the outsole 20 may be mounted in the conventional manner; the layer S arranged between the insole 16 and the outsole 20, in fact, does not adversely affect gluing of the latter onto the semi-finished article 11.

With reference to Figures 8, 9, 10 and 11, advantageously, this waterproofing method may also be used in the case where a breathable membrane is mounted on the bottom of the semi-finished article 11.

The breathable membrane directly combined with the insole or a breathable support preferably made of fabric or thin felt will form the element 28 on which the element 36 made of felt or other compressible and breathable material will be mounted, whereby it is important to ensure that the element 28 projects preferably about 5 mm from the edge of this element 36.

By providing a suitable mask or template 22 it is then possible to perform sealing of the bottom in a manner similar to that described above.

In this case, the template 22 must have an insert 23 in the region of the element 36 joined to the breathable element 28. This insert 23 covers the element 36 (felt or other compressible and breathable material) and the breathable element 28, leaving the outer edge of the element 28 exposed, preferably by 5 mm, thus allowing the jet of spray Z to reach the said outer edge 30 of the membrane and the remaining perimetral zone 31.

The element 36 (felt or the like) during the subsequent pressing step will also prevent the material S, following compression, from being able to flow over the element 28, affecting its breathable nature.

By sealing the bottom, as described above, and the breathable element 28 along its outer perimeter 30 and 31, the water is prevented from penetrating inside the semifinished article 11, while the breathability of the semi-finished article 11 is ensured, in the case where an insole 16 with a breathable area or insert 26 is combined with the element 28.

In this way the critical problems associated with the types of known waterproofing systems are overcome.

In the description reference has been made to a shoe 10 which is made using the "AGO" assembly technique. The method according to the invention, however, may be applied also in the case where the shoe 10 is made using differing manufacturing techniques, for example the "ideal" or "strobel" techniques.

In the case of the "strobel" technique, which is understood as referring to the use of an insole made of fabric or other semi-rigid material, or similar manufacturing techniques, with reference to Figures 12 and 13, the insole 43 is joined preferably by means of stitching (stitch 41) to an edge band 40 which is perforated or made of thin mesh or is heat-melting or thermoadhesive, with a width of about 1 cm, and which in turn is joined preferably by means of stitching (stitch 42) to the upper 15, while the membrane 17 and the lining 19 are joined together by means of stitching (stitch 41) directly to the insole 43 together with the edge band 40. The spraying of polyurethane as described above (see Figure 14) with the aid of a template 22, and the subsequent pressing ensure that the material S is distributed over the entire insole 43 and on the edge band 40 where, being inserted into its meshes, it will seal the membrane 17 at its points of contact with the upper 15 and the insole 43.

In the case also of the "strobel" technique it will be possible to mount on the bottom a breathable element 28 according to the method described above.

The same comments made in connection with the "AGO" technique are applicable to the "ideal" technique, where the stitch joining the upper 15 and insole 16 is on the outside.

A further embodiment of the method according to the invention envisages the use of a spraying device 24 mounted on an automated arm. In this case, the relative moment of the sprayer 24 and the semi-finished article 11 is no longer performed manually, but by means of mechanical devices which are controlled by suitable software. This solution ensures the uniformity of the spraying operation.

As will be clear to the person skilled in the art, with the method according to the invention it is possible to ensure effective waterproofing of the semi-finished article consisting of an upper fixed to an insole.

With the method according to the invention it is also possible to waterproof semifinished articles in which breathable inserts are incorporated.

Moreover, the method according to the invention does not adversely affect the comfort of the shoe obtained by mounting an outsole on the semi-finished article.

With regard to the embodiments of the method for the production of impermeable and breathable semi-finished articles described above, the person skilled in the art may, in order to satisfy specific requirements, make modifications to and/or replace elements described with equivalent elements, without thereby departing from the scope of the accompanying claims.