EP3579717B1

EP3579717B1 - High-comfort stretch boots obtained from an improved process

Info

Publication number: EP3579717B1
Application number: EP18714599.0A
Authority: EP
Inventors: Lorenzo MASIERO
Original assignee: Masiero Lorenzo Srl
Current assignee: Masiero Lorenzo Srl
Priority date: 2017-02-08
Filing date: 2018-02-07
Publication date: 2021-04-07
Anticipated expiration: 2038-02-07
Also published as: EP3579717A1; IT201700013395A1; WO2018146600A1

Description

TECHNICAL FIELD

The present invention is related to footwear items and production methods thereof. Particularly, it is related to boots made of elasticized natural leather obtained by means of an improved manufacturing process.

BACKGROUND ART

Various techniques are known for making boots using natural leathers obtained by treating the skins of cows, sheep, reptiles or other animals. These materials are intrinsically non elastic or at most have a limited elasticity depending on the thickness, the origin of the leather and the tanning treatment to which it is subjected (the elastic modulus is between 0.1 and 0.5 GPa, at least two orders of magnitude higher than the elastomers).
For example, document FR791196A discloses a method of manufacturing a boot from a single piece of leather material.
Compared to other footwear articles, the design and construction of boots must take into account the non-elastic nature of the leather. To make skin-tight boots it is not advisable to use stiff leather, which is easier to work with and it is preferable to use soft, low-thickness leather whose processing is however much more difficult and requires specific skills.
Moreover, the non-elastic nature of the leather and the need to ensure a close-fitting to the leg, require insertion of means into the boot that make more comfortable and easier to put on and to take off the boots especially those that reach or exceed the knee. For example, some types of known boots made of substantially rigid natural leather have a zip closure along the upper while others comprise stitched elastic inserts (named "gores") stitched into either side of the upper.
In other types of boots, the zip or the lateral elastic insert are replaced by other fastening means such as laces and eyelets. All these known types of leather boots do not present a "one-piece shape" i.e. a structure in which the upper and the leg of the boot are integrated with each other (i.e. as in the known stretch boots made of elastic fabric). In fact, due to the 2-dimensional nature of the natural leather it is unavoidable the presence of externally visible seams (or stitching or joining lines) that join the different components of the boot (e.g. upper, leg and heel) in order to create a tubular structure. To the best knowledge of the present inventor there are no known commercial boots made of leather made up of less than three components and having not less than two or three seams (for each pair of boots).
In these known types, the presence of external seams is not always appreciated as they can reduce comfort and are considered unaesthetic. In fact, sometimes they are masked by the application of decorative coverings in leather or fabric.
In view of the aforementioned peculiarities of the boots, the working techniques developed over the years have consequently been adapted to substantially rigid materials and to a "multi-piece shape", i.e. a boot structure in which two or more pieces of leather are joined together by means of one of the fastening means previously cited to allow for wearing and for removing the boots, operations not always easy in practice, especially in those types of boots very close-fitting to the legs.

Technical Problem

In recent years, trends in women's fashion and availability of synthetic materials with mono or bi-directional elasticity (called, respectively, mono-elastic and bi-elastic), such as elasticized fabrics or elasticized imitation leather, have brought to the market a new type of stretch boots (in short named "stretch boot"). In such boots the upper is made from a mono-elastic or a bi-elastic tubular fabric whose elastic properties allows to integrate the upper and the leg of the boot without seams or joining lines: in practice such boots are of the "single-piece" type and look like high denier stockings with soles and heels applied on them. These elastic boots, which in the following will be defined as "traditional type", have some drawbacks.
Firstly, the synthetic nature of the stretch materials which imitate the natural leather (for instance, based on polyester and elastane) leads to poor or no breathability of the boots. As a consequence hygienic problems (e.g. unpleasant odors, fungal infections, etc.) arise as well as a poor comfort feeling (e.g. skin irritations) especially with prolonged use. Moreover, even if a breathable stretch fabric was used, the boot would not assume the features and the hand of one made of natural leather, and would not be suitable for use in harsh or rainy climates. Finally, the stretch materials used do not present the valuable characteristics and attractiveness of natural leathers, especially in the luxury market.
For these reasons, footwear artisans and factories have dedicated themselves to experiment with new materials suitable for making boots in natural stretched leather that are able to meet the growing demand from a high-end female customers. However, according to the best knowledge of the present inventor, these attempts have proved unsatisfactory despite the strong market demand and availability of elastic natural leathers (for example those made by the French company Cuirs du Futur), which are potentially useful for achieving this task in combination with the great wealth of technical knowledge in the footwear field.
For example, currently elasticized leather boots are available in the market, but these are made by joining at least three shaped pieces (for single boot) of elasticized leather: for example, one to make the leg of the boot, the second piece for the upper and the third for the heel counter. These well-known leather boots do not ensure the skin-tight effect on the legs and a good comfort feeling that "one-piece" stretch boots made of stretch fabric on the contrary let.
As previously mentioned, there is a strong demand by the luxury market for close-fitting leather boots that look like a "single piece", but this demand is obviously not satisfied by the known elasticized leather boots. The fulfillment of this need requires improvements of the current production processes that at present are not adequately addressed for this type of footwear item. In fact, manufacturing of traditional stretch boots involves processing techniques typical of the rubber-plastic sector (e.g. molding of elastomeric materials) or textiles (e.g. production of tubular fabric articles like stockings). In this regard, there are scarce information useful to the expert coming from the patent literature.
For example, in the Japanese document JP2006149660A in the name of Yamamoto Keika 2006-06-15 ("Stretch boots and manufacturing method"), a stretch fabric boot and the manufacturing process thereof are described. In another document ( JP3641634B1 ), the same inventor provides the solution to the problem of economically making a seamless elasticized boot with an excellent appearance. However, these known methods are not useful for the purpose of the present invention as they are exclusively addressed to the realization of boots made of stretch fabric and not of elasticized natural leather.
In the footwear field, particularly in small-scale artisan shoe workshops, there is a tendency to maintain secret the know-how on materials and working techniques. Therefore, according to the characteristics of the end products available on the market, it is difficult or impossible for the person skilled in the art to deduce the characteristics of the processing steps and of the materials used through a "reverse engineering" activity. All this prevents the advancement of knowledge in the filed and therefore the availability of elastic boots in natural leather with the characteristics required by the market specifically the luxury market.
In conclusion, for the reasons outlined above, at the state of the art it has not properly addressed the problem of making an elasticized boot from a shaped single piece of elasticized natural leather, which present not visible seams and is able to guarantee a perfect adherence to the leg.

DISCLOSURE OF INVENTION

Object/scope of the invention

Therefore, in view of the above drawbacks of the prior art, the present invention intends to overcome the existing disadvantages related to footwear items and particularly to boots made of elasticized natural leather.
Accordingly, it is a first and main object of the present invention to provide a footwear item made of elasticized natural leather and obtained through an improved manufacturing process that allows to obtain items having superior comfort and appearance with respect to known ones. In particular, this object includes the manufacturing of skin-tight boots that even if made of natural leather and not of elasticized fabric resemble high denier stockings and similarly to stockings are easy to wear and easy to take off from the leg.
Within the main task described above, it is a second object of this invention to disclose a structure of elasticized boot in natural leather, as well as the related manufacturing process, able to guarantee a complete adherence to the leg and foot and yet breathability.
In addition, within the first and second tasks described above, a third important object of the present invention is to obtain an elasticized boot, with no evident external seams, by means of an improved process which starts from a single piece of suitably-shaped elastic natural leather. In particular, the third object includes an elasticized boot obtained by means of said improved process wherein such seams can be reduced to a single one, that is the minimum possible for a 3-dimensional item made from a flat and non-tubular material.
Furthermore, within the tasks described above, it is a fourth object of the present invention to disclose a elasticized footwear item, particularly a boot, made of natural leather obtained by means of a process that can be applied to a wide range of shapes and range of natural leather, in such a way as to follow fashion trends and fulfill market demands specifically of the luxury market.
Finally, the last object of the present invention is to provide said footwear item and said process by means of known technologies.
Additional objects and advantages of the invention will be set forth in part in the detailed description which follows and in part will be obvious from the description, or may be learned by practice of the invention.

Technical Solution

The objects of the present invention are achieved by a high-comfort elasticized footwear item obtained from an improved production process, as set forth in the independent claim, whose detailed technical elements are identified by the corresponding dependent claims. The aforementioned claims, to which reference should be made for the sake of brevity, are hereinafter specifically and concretely defined and are considered an integral part of the present patent specification.

Description of Drawings

The present invention will be more fully understood by reference to the following drawings which are for illustrative purposes only:

Figure 1 depicts a three-dimensional view of the footwear item according to the preferred embodiment of this invention, represented by a female boot made of "velour stretch";
Figure 2 represents, again with reference to the preferred embodiment of the present invention, in (a), the 2-dimensional model of a typical piece of shaped elasticized leather which, once seamed, allows to construct the leg part of the boot integrated to the upper part, while in (b), a detail of the structure of the shaped elasticized leather one-piece;
Figure 3 is a schematic view from below of the boot during the assembling step, again with reference to the preferred embodiment according to the invention.

These figures illustrate and demonstrate various features and embodiments of the present invention, and of the manufacturing method thereof, but are not to be construed as limiting the invention.

Advantageous Effects of Invention

The footwear item obtained through the improved manufacturing process herein disclosed have a number of remarkable advantages which cannot be achieved by prior art compounds as it will be apparent to those skilled in the art.
The first advantage consists in a boot featuring an highly aesthetic "one-piece" appearance, i.e. having only one external seam (unlike the known leather stretch boots that have at least two or three external seams) that represents the smallest possible number for a 3d shape made from a flat 2-dimensional single piece of leather. In other words, the boot structure and the manufacturing process, result in an elasticized boot made of natural leather that is close-fitting to the foot and to the leg, and looks like an high denier stocking. Remarkably, it is possible to obtain this "one-piece" appearance in a wide variety of leather boots shapes.
Furthermore, boots according to the present invention are easy to wear and easy to take-off, just like a stocking. At the same time, they guarantee an optimal breathability and comfort that traditional known boots, i.e. based on synthetic tubular stretch fabrics or imitation leather, cannot achieve.
All these advantages and achievements have been obtained by the present inventor through non-trivial process innovation.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

For the purpose of understanding the specification and the appended claims, in the following description and claims the term "boot" designates in the broadest meaning a footwear item for men, women or children, with or without fastening means, provided with a part (for the sake of clarity is named "leg of the boot" or "leg part" in short) seamed to the upper of the boot and which generally reaches or exceeds the knee but can also reach a lower height. Therefore, the term "boot" includes footwear such as half boot, thigh boot, ankle boot, or other technically equivalent types, even if defined with terms other than those used in the present description. For the sake of brevity, the terms "mono-directional elasticity" or "mono-elastic elasticity" referred to a fabric (or similar materials) designated the physical property of (a) having a single direction of maximum elastic elongation, following the application of a tensile force, and (b) being substantially rigid in the direction orthogonal to the direction of maximum elongation. Similarly, the terms "bi-directional elasticity" or "bi-elastic" shall mean, mutatis mutandis, an elastic material capable of reversibly extending along two distinct directions.
For the sake of brevity, in the description and claims the same term "piece of elasticized leather" (singular or plural) and the same reference numbers, have been used to indicate, first the raw component obtained by making elastic a natural leather, then the semi-component obtained after precision cutting of such raw component, and finally the component of the boot obtained at the end of the assembling step. Mutatis mutandis similar considerations also apply to the lining. In both cases, the different meaning will be clear to the skilled in the art from the description.
In addition, the terms " one-piece" or "single-piece" refer to a structure in which the upper and the leg of the boot are integrated with each other (i.e. as in the known stretch boots made of elastic fabric) and are made from a single piece of suitably shaped elasticized leather (for single boot and not for a pair of boots) whose edges are joined together by a single seam (for single boot and not for a pair of boots) which is not externally visible.
Finally, in the present invention the term "natural leather" or simply "leather" will designate any animal hide or skin subjected to tanning, even if from a technical point of view the term "leather" is more correctly used to define the resulting final product from the chemical or vegetable processing of such animal skin regardless of intended use.
Accordingly, for the sake of clarity, the terms "elastic leather " or "elasticized leather" will indicate a natural skin which has been made mono-elastic or bi-elastic through appropriate procedures and treatments.

Best Mode for Carrying out the Invention

With reference to the enclosed figures, in the preferred embodiment of the present invention, illustrated here by way of a non-limiting example, the footwear item made of elasticized natural leather is a "one-piece" woman's boot which covers the leg up to the knee, made of mono-elastic natural suede leather.
Said elasticized boot is indicated with the number (1) and is obtained from a single piece of elasticized natural leather (10) through the method which will be described hereinafter. By way of non-limiting example of the present invention, said elasticized natural leather (10) consists of a piece of natural leather (11) and a piece of elasticized fabric (12) which were first suitably shaped and then joined to a fabric lining (13). Said fabric lining (13) consists of a foot lining (131) and a leg lining (132) which were also suitably shaped, so as to obtain a 2-dimensional model of the boot such as that illustrated in the enclosed figure 2.
Then the edges of the 2-dimensional model are sewn to form a leg part of the boot joined to the upper part. To this part are applied during assembling: the reinforcing elements (toe and heel counter), the innersole, sole and heel, the innersole placed above the undersole, and other components. Without departing from the more general scope of the present invention, said components can vary in number, aspect, size, or they can be integrated with each other, depending on the needs and the model of the boot.
In the preferred embodiment of the present invention, the elasticized boot according to the present invention is obtained by means of a process comprising the following steps, listed here and described as a non-limiting example of the present invention:

1. Boot design and material selection;
2. Leather and lining cutting;
3. Leather and lining crimping;
4. Leather and lining trimming;
5. Skin and a lining sewing;
6. Boot preparation and mounting;
7. Boot finishing.

Step 1: Boot design and material selection.

Due to the elastic nature of the material, designing the shape of the boot according to the invention is of fundamental importance in order to obtain an item characterized by superior fit and comfort and able to guarantee a complete adherence to the leg as a stocking. In fact, starting from the characteristics of the elasticized starting leather and evaluating the overall design of the boot, the designer must identify in which portions of the boot is required greater elasticity.
The method for making the boot according to the present invention starts with an elasticized leather piece (10) comprising a piece of natural leather (11) coupled with an elasticized fabric (12). Preferably said natural leather (11) is suede but other types can also be used provided they have a thickness of between 0.3 and 1.0 mm and similar softness.
Preferably, said stretch fabric (12) is a mono-elastic fabric having a mono-directional elasticity and a thickness selected so that said coupled leather has an overall thickness between about 0.4 and 2 mm. On the market are available various elasticized fabrics suitable for the purpose which are known to those skilled in the art.
Coupling of said natural leather (11) with said elasticized fabric (12) can be performed by known techniques, for example by immersion in elastomeric materials, calendering or other equivalent techniques. Alternatively, elastic leathers can be found on the market, for instance those produced by the French company Cuirs du Futur.
Besides material selection, in this step it is accomplished the selection of shoe-lasts and shoe patterns which will be used, first, to obtain the different components of the boot, and then during working operations and boot assemblage.

Step 2: Leather and lining cutting.

This step includes cutting of the elasticized leather (10) and of the lining (13). The elasticized leather (10) is cut to size according to a cutting profile defined by a shoe patterns, taking care to orientate the piece properly so that the unidirectional elasticity is directed along the transverse direction (T) of the boot. The cutting operation is made by means of a known cutting tool, for example a hand cutter in such a way as to advantageously determine the curling of said elasticized skin and facilitate the conformation to the mold of the boot.
In a similar manner it is performed the cutting of the lining (13), which includes a foot lining (131) made of leather and a leg lining (132), made of stretch fabric, able to guarantee proper breathability and facilitate the sliding of the foot inside the boot when it is put on and taken off.

Step 3: Leather and lining crimping.

In this step, the cut elasticized leather (10) and the cut lining (13) are placed on a crimping machine to form the boot. This operation must take into account the unidirectional elasticity characteristics of the components (10) and (13) and the overall design of the boot.
The crimping operation is carried out by means of a known crimping machine at a temperature of between 80 and 180 °C for a time comprised between 1 and 300 minutes, depending on the characteristics of the natural leather (11), which is not always homogeneous since the starting material consist of a natural leather piece.
Advantageously, the present inventor has experimentally verified that the application of a fabric softener facilitates the boot shaping, especially in those areas characterized by high curvature such as the instep and the leg part. Preferably, the softener is selected from those containing nonionic surfactants in a silicone emulsion. However, other technically-equivalent softeners can be used.
In the end product, the use of a fabric softener yields an elasticized leather boot free of wrinkles and elastic tensions (tensions make the boot "pulling on one side"), featuring superior aesthetic and comfort, unlike those traditional known at the state of the art. In light of the experiments carried out with different conditioners, this remarkable technical effect seems to be related to the fluidizing action of the fabric softener, which stretches the fibers in the natural leather (11), in the stretch fabric (12) and in the lining (13) and compensates the different elastic modules of these components (11,12,13).
In fact, it is the different elastic behavior of these components that determines the onset of wrinkles and elastic tensions that affect the aesthetics and comfort in this type of boots. At the end of the crimping step, a conditioned elasticized leather and a conditioned lining are obtained which, for the sake of simplicity, in the present description will be indicated with the same numbers (10) and (13) respectively.
Through the description provided herein it will be apparent to the skilled in the art that this manufacturing step can not be inferred from the end product, even if it determines the properties of the elasticized boot according to the present invention.

Step 4: Skin and a lining trimming

Using known techniques, in this step the elasticized leather and the lining obtained from the crimping operation are trimmed manually with a hand cutter and the aid of a precision shoe patterns so as to conform them to the final shape of the boot according to the design defined in the previous Step 1. At the end of the crimping operation, a trimmed elasticized leather and a trimmed lining are obtained. For the sake of simplicity, in the present description they will be indicated with the same numbers (10) and (13) respectively.

Step 5: Skin and a lining sewing

The trimmed pieces of elasticized leather (10) and the trimmed pieces of lining (13) obtained in the previous step are superimposed one onto another and then sewn together along the perimeter. In particular, this operation produces: a first internal seam to join the edges of the foot lining (131) along the perimeter (P₁), and a second internal seam to join the edges of the leg lining (132) along the perimeter (P₂).
Said components (10) and (13) must be oriented properly so that once they are sewn together, the unidirectional elasticity along the transverse direction (T) of the boot is preserved. Preserving the unidirectional elasticity during boot manufacturing steps represents an important object of the present invention. To achieve this and at the same time to ensure high adhesion of the lining to the elasticized leather (10) during the use of the boot, the inventor has developed a technique in the application of said first internal seam. This technique consists in the use of two different threads: an elastic thread (e.g. in elastane) where elasticity is required to make easier boot fitting, such as in the upper part (S) of the leg part; an high-resistance thread (e.g. a nylon thread) is used in those areas more subjected to wear, such as in the lower part (I) of the leg part. Moreover, a layer of glue is spread on the edges of the elasticized leather (10) and of the lining (13) to promote adhesion.
In this step, one or more additional internal seams (preferably two with non-elastic thread) and one or more reinforcing elements (13) are applied to improve rigidity of the boot and prevent it from collapsing once worn.
Optionally, in the upper part (S) of the upper leg, an anti-slip element (14) made of a silicone material, or other similar material able to adhere to the user's leg, can be applied, preferably glued.

Step 6: Boot preparation and mounting

According to the present invention, the preparation for mounting the boot involves known techniques and materials. They include the application, by means of glue or mastic and specific machinery/tools, of aids for keeping the boot components in position and for giving them the shape according to the initial design. As usual in the footwear industry these aids are, for example the tip and the heel counter.
In summary, the following operations are performed: first, the elasticized leather (10) (i.e. the upper part joined to the leg part) is put over a plastic shoe-last; the operator thus takes the shape and fixes the innersole (15) by means of shoe tacks; then he takes said elasticized leather (10) and fixes it with glue over said form using a tack lasting machine; finally he proceeds with the manual shaping of said elasticized leather (10).
In this step, the operator must join to the sole (15) the lower surface (∑_inf) of the boot limited by the edge (C), making sure that the lower surface (∑_inf) is as regular as possible or, in geometrical terms, for all points (x,y) belonging to the lower surface (∑_inf) the normal versor n⊥(x,y) has a variation lower than a prefixed Δ value corresponding to an acceptable quality level of the boot. In fact, for various reasons the single piece of elasticized leather (10) does not fit perfectly with the shape of the boot (1) provided for in the design step (the same problem also applies in the case of models consisting of several portions of elasticized leather).
In fact, elasticized leather (10) is made of a natural material, whose elastic property are never perfectly identical nor repeatable (often not even within the same batch of leather); moreover, the tolerances and the unavoidable errors introduced during machine and manual working operations have to be considered; in addition, the elasticity of said piece of elasticized leather is never perfectly unidirectional and directed along the direction (T), due to the tolerances in cutting and stitching and the intrinsic curvature of the boot; finally, the piece of elasticized leather (10) geometrically has two dimensions but must fit to a three-dimensional shape.
In summary, these factors produce a limited, or often poor, adhesion of the lower surface (∑_inf) of elasticized leather (10) to the plastic shoe-last used during the assembly phase. In turn, this phenomenon causes wrinkling, i.e. areas in which the leather is "abundant" or "scarce", that not only represent unacceptable aesthetic defects but also functional defects as they can lead to the yielding and breaking of the elasticized leather during use.
Therefore, during the mounting step the operator must take these aspects into consideration and consequently must make appropriate corrections. After a careful analysis of the known stretch boots, the present inventor believes that these factors have not been considered and managed properly, and for this reason stretch boots made of natural stretch leather are not currently available in the market despite the extensive knowledge and technology available in the footwear field.
The present inventor has thus codified a method to guarantee optimal adhesion of the lower surface (∑_inf) to the shape of the foot and to minimize or eliminate defects or imperfections. Said procedure, illustrated here by way of example and not limitation of the present invention with reference to the Figure 3, comprises the following sub-steps:

i. The lower edge (C) which limits the lower surface (∑_inf) is fixed to the innersole (15) with mastic, or other adhesive, and optionally with shoe tacks;
ii. The degree of deviation of the lower surface (∑_inf) with respect to said shape and to the maximum acceptable deviation value Δ is determined;
iii. The border (C) is divided into a certain number of segment-edges C_i of equal length, where i is an integer which preferably varies between 4 and 16;
iv. A tension is applied to the segment-edge C_i in order to pull it and fix it, preferably by means of shoe tacks, on a perimeter point of the surface of the innersole (15);
v. The degree of deviation of the lower surface (∑_inf) with respect to said shape and to the overall conformation of the boot is evaluated;
vi. Optionally, heat is applied to minimize or eliminate the elastic stresses introduced during the mounting step;
vii. The sub-steps from iv. to vi. are repeated to another segment-edge C_j, with j≠ i, until said deviation is lower than the predetermined value corresponding to the acceptable quality level.

Preferably, the edges C_i can be scanned sequentially following a direction, for example a clockwise, but other sequences may be used, for example by choosing two-by-two opposed segment-edges C_i and C_j.
This procedure can be implemented manually, or by using a machine provided with a plurality of grippers able to hold and independently pull one or more of said edges C_i. In this case, the operator acts on the grippers so as to pull a segment-edge (C_i), where i is an integer, preferably equal to or greater than 8, and fit the lower surface (∑_inf) of the elastic leather (10) to the shape of the foot. Alternatively, or in combination, this fixing operation can be carried out manually.
Through the description provided herein it will be apparent to the skilled in the art that this processing step can not be inferred from the end product, even if it determines the remarkable properties of the elasticized boot according to the present invention.

Step 7: Boot finishing.

The boot is finally subjected to a number of finishing processes involving techniques and machines known in the field of footwear items. By way of example and without any limitation of the present invention, the finishing step comprises the following processing sequence: first the boot is inserted in an oven to stabilize its shape; then it is subjected to scraping for removing residues of skin or glue; then a pounding machine is used to flatten the seams and the tips of shoe tacks applied in the previous steps. This step also involves to form an impression of the heel and to mount the heel by means of mastic. To conclude, the following operations are made: removal of the shoe-last of the boot introduced in the previous preparation step; insertion of the leather sole; ironing, cleaning and packaging of the finished boot.
In order to achieve the objectives of the present invention, ironing plays an important role and it is carried out by means of special tools heated to a temperature between 70 and 150 °C, and on special preformed and heated legs. In fact, the ironing allows to further flatten the internal seams and to eliminate any wrinkles that may be present. Alternatively or in combination, a hand-ironing step can be added.
In conclusion, it is apparent to those skilled in the art that the present invention fully achieved the intended aim and objects. In fact, through the invention described hereinabove, an elasticized boot in natural leather obtained by means of an improved manufacturing process has been disclosed. Said process allows to obtain a boot featuring superior aesthetic and comfort unlike those traditional known at the state of the art.
Although the description and examples above contains many details, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Therefore, any modification of the present invention which comes within the scope of the following claims is considered part of the present invention.
In the appended claims, reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." Where the characteristics and techniques mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example, but not limitation by such reference signs.

Claims

A stretch boot in natural leather, obtained from a single piece of elasticized leather (10) through the method comprising the following steps:
a) Obtaining one or more shoe-lasts and shoe patterns for each of the components of said boot, and accordingly selecting a single portion of elasticized leather (10) having an overall thickness comprised between 0.4 and 2 mm, said elasticized leather (10) comprising a natural leather (11) and an elastic material;

b) Using one or more of said shoe patterns to cut to size a single portion of said elasticized leather (10) so as to include at least a leg part and a foot part, and so that the unidirectional elasticity is directed along the transverse direction (T) of said boot;

c) Using one or more of said shoe patterns to cut to size the lining (13) so that the unidirectional elasticity is directed along the transverse direction (T) of said boot, said lining (13) comprising a foot lining (131), made of leather, and a leg lining (132) made of stretch fabric;

d) Forming said single portion of elasticized leather (10) and said lining (13) by means of a forming or a preforming process performed with a crimping machine, so that the unidirectional elasticity of said portion (10) is directed along the transverse direction (T) according to the overall design of said boot defined in the previous step a), said forming process being performed preferably at a temperature between 80 and 180 °C degrees for a time comprised between 3 and 30 minutes, said forming process being performed in association with a fabric softener to compensate the different elastic moduli of said portion (10) of elasticized leather, of said foot lining (131) and of said leg lining (132), so as to remove, or reduce, wrinkles and elastic stresses;

e) Precision-cutting said single portion of elasticized leather (10), said foot lining (131) and said leg lining (132), obtained at the end of the previous step, with the aid of a precision shoe pattern in order to conform said lining parts (131,132) to the final form of the boot according to the design defined in the previous step a), and to obtain a trimmed single portion of elasticized leather (10), a trimmed foot lining (131) and a trimmed leg lining (132);

f) Attaching by sewing said trimmed foot lining (131) and said trimmed leg lining to the foot part and to the leg part, respectively, of said trimmed single portion of elasticized leather (10), so that the unidirectional elasticity of said portion (10) is directed along the transverse direction (T) according to the overall design of said boot defined in the previous step a), said sewing comprising at least:
- a first inner seam made along the perimeter (P₁) for the trimmed foot lining (131), said first seam being made by means of a non-elastic thread having high-breakage resistance, preferably a nylon thread;

- a second inner seam made along the perimeter (P₂) for the trimmed leg lining (132), said second seam being made in the lower part (I) of the leg part by means of a non-elastic high-breakage-resistance thread, preferably a nylon thread, and in the upper part (S) of the leg part by means of an elastic thread, preferably a spandex thread;

g) Attaching by sewing the longitudinal edges (L) of said trimmed single portion of elasticized leather (10) in order to form a substantially tubular structure wherein the unidirectional elasticity is directed along the transverse direction (T) according to the overall design of said boot defined in the previous step a), said sewing being made by means of a non-elastic high-breakage resistance thread, preferably a nylon thread;

h) Applying, by gluing or additional internal seams, one or more reinforcing elements (13) to improve boot stiffness and prevent boot collapsing when worn, said additional internal seams, being preferably two and made with non-elastic thread;

i) Optionally, applying a non-slip element (14) in the upper part (S) of the leg part, preferably by gluing, said non-slip element (14) being made of a silicone-based material, or a material able to adhere to the user's leg;

j) Minimizing the deviation between the lower surface (∑_inf) and the shape of the foot part through a manual procedure or a machine-assisted procedure, comprising the following sub-steps:
i. Placing a shoe-last selected in the previous step a) in the lower end of said substantially tubular structure made of said trimmed single portion of elasticized leather (10);

ii. Attaching to the innersole (15) the lower edge (C) which limits said lower surface (∑_inf), preferably with mastic or other adhesive and optionally with shoe tacks;

iii. Evaluating the degree of deviation of said lower surface (∑_inf) compared to said foot part shape;

iv. Dividing said lower edge (C) in a number of leather borders C_i, preferably of equal length, where i is an integer number between 4 and 16;

v. Pulling and fixing a leather border C_i, preferably by means of shoe tacks, on a perimeter point of the innersole surface (15);

vi. Evaluating the degree of deviation of said lower surface (∑_inf) compared to said foot part shape and to the overall shape of the boot;

vii. Optionally, applying heat to minimize or remove the elastic stresses introduced during the boot making steps;

viii. Repeat sub-steps from iv. to vi. to another C_j leather border, until said degree of deviation is below a predetermined value Δ corresponding to an acceptable quality level;

k) Subjecting said boot to one or more finishing operations selected from the group consisting of: shape stabilization of said boot, preferably in a oven ; removal of leather or glue residues by scraping; flattening the seams made in steps f), g) and h) with a pounding machine; taking an impression of the heel and then fixing the heel, preferably by means of mastic; insertion of the leather innersole;

l) Ironing of the boot (1) with a heated tool at a temperature between 70 and 150 °C on leg-shaped preheated forms to further remove residual stresses and to flatten the internal seams.
The boot according to the preceding claim, wherein said leather is selected from the group consisting of: suede, bovine or calf leather, lambskin leather, or a combination thereof.
The boot according to claim 1 wherein said elastic material is an elasticized fabric coupled to said natural leather (11), preferably a mono-elastic breathable stretch fabric.
The boot according to one or more of claims 1 to 3 wherein said natural leather (11) has a thickness comprised between 0.3 and 1.0 mm.
The boot according to claim 3 wherein said elasticized fabric has a thickness in a range between 0.1 and 1.4 mm.
The boot according to claim 1 wherein said fabric softener is a silicone-based softener comprising nonionic surfactants.