EP1872678B1 - Rigid-shell shoe - Google Patents

Description

The invention relates to a shoe comprising a rigid shell. In particular but not exclusively the invention relates to a shoe for the practice of sliding, for example skiing. It may also relate to other types of shoes having a rigid shell such as walking shoes, or shoes whose part of the rod is a rigid element (buttress, collar, etc. ..). It also relates to a pair of shoes and a heating machine for shaping the one or more shoes.

In known manner, a shoe for the practice of skiing comprises a rigid shell which is made of plastic material and a comfort inner boot which is formed mainly by a foam. Generally the shell is composed of a shell bottom that wraps the foot, and a rod that goes up along the user's ankle.

The hull with its rigidity properties transmits the forces between the foot and the gliding board. The liner envelops the foot of the user, it ensures the comfort of the foot inside the hull. It also transmits to the different zones of the foot or ankle the stresses to which the hull is subjected.

In order to ensure good transmission of the forces between the foot and the gliding device, the hull and the bootie must conform to the shape of the skier's foot. But the feet have complex shapes that are variable from one individual to another.

To allow an adjustment of the volume of the foot to a shoe, the shell is equipped with hook mechanisms or other equivalent devices that allow to change its interior volume.

But it is also necessary to avoid that the liner locally exerts an overpressure on the foot. Such overpressure disrupts the perception of solicitations for an experienced skier. For an occasional skier, it produces a feeling of discomfort that in the long run turns into pain.

Conversely, it is also necessary to avoid that the foot floats in the shoe because of an empty space between the foot and the liner or between the hull and the liner. Such a flutter makes driving skiing imprecise.

Thus, to precisely adapt the shoe to the volume of the foot it is known to work the shape of the shoe. For example the patent application FR2788410 describes an embodiment of a slipper according to which yarns are cut into the wall of the slipper to reduce its thickness locally or, on the contrary, to add shims of thickness.

Also it is known to modify the volume of the liner or by injecting air or gel into the pockets provided for this purpose, or conversely by creating a vacuum in compartments filled with filling material. The documents US3758964 , US3925916 , WO01 / 87100 , FR2597729 , EP672363 describe ski boots with such slippers. Also it is known to use memory foam shape, or thermoformable foams. Patent applications EP004829 and FR2739760 illustrate the production and shaping of such slippers thermoformable foam.

These techniques give good results, however their field of application is limited because the deformation of the liner is limited by the wall thickness of the liner and the interior volume of the hull.

Also, in some cases we resort to a deformation of the hull itself.

However, deforming a shell requires locally heating the wall at an elevated temperature and requires heavy equipment, hot air blower 500 ° C, including caliper and hydraulic piston, which is introduced into the shell to exert a thrust on its walls. From where a certain inaccuracy as for the localization and the amplitude of the deformation because one works on the bare hull. This is a specialist job. It can also be observed a deterioration of the external appearance of the shoe in the areas that have been heated.

There are also shoes whose shell is made with different stiffness portions. In particular these shoes have more flexible portions in the sensitive areas of the foot, including the malleolus area and metatarsals. Patent applications EP916273 and WO2004052134 describe such modes of construction.

Also the German utility model DE8611889 describes a shoe whose portions are made of a thermoplastic material, To deform the shell and adapt to the shape of the foot of the user is heated locally these portions beyond the softening point of the thermoplastic material which is order of 100 ° C, ie much lower than the softening temperature of the rest of the shell.

These modes of construction give good results, nevertheless they are not completely satisfactory.

For the EP916273 the goal is to press the foot against reinforced areas of the hull that bypass the sensitive areas of the foot, there is no frank deformation of the hull, and therefore no significant improvement in comfort for a foot that would feel overpressure of the shoe.

For the other two documents, the structure of the hull becomes hybrid. The less rigid portions of the hull are made of a completely different material than the rest of the hull. It is therefore necessary to strengthen the hull to compensate for the local loss of rigidity in these sensitive areas. The less rigid portions are areas of weakness of the shoe that are less resistant to impact and wear. In addition, as the material is different, the appearance of less rigid portions is different from the rest of the shell and ages differently.

The document US 6,025,414 discloses a thermoformable composition which comprises a gelling agent for stiffening said composition in a proportion of between 33% and 63%.

given this state of the art, there is a need for a ski boot, which is improved in that its volume can be modified by local deformation, but without significant loss of rigidity and without significant alteration of the external appearance of the ski boot. the shoe.

According to the invention, the shoe comprises a shell or a shell element, made of a rigid plastic base material whose softening point is greater than 170 ° C. The shoe is characterized in that at least in a local portion of the shell, or the shell member, the shell material contains an additive having a melting temperature of less than 100 ° C, preferably 80 ° C in a proportion of between 3 and 45%, preferably 10 to 25%.

Preferably, the additive is a polymer based on caprolactone or caprolactane.

The heating machine comprises a support provided to receive at least one shoe in a longitudinal direction defined by the sole, a hot air generator integrated in the support. It is characterized in that it comprises at least two blowing nozzles oriented vis-à-vis and located on each side of said longitudinal direction.

• La figure 1 représente une chaussure de ski vue du côté extérieur.
• La figure 2 montre la chaussure précédente vue du côté intérieur.
• La figure 3 est une courbe explicative de l'invention.
• Les figures 4 à 7 illustrent différents modes de réalisation d'un insert.
• La figure 8 montre un premier mode de construction d'une machine de chauffage qui ne fait pas partie de la présente invention et qui est donnée à titre informatif.
• Les figures 9 et 10 sont relatives à un autre mode de construction d'une machine de chauffage qui ne fait pas partie de la présente invention et qui est donnée à titre informatif.

The invention will be better understood with reference to the description below and the accompanying drawings which form an integral part thereof.

• The figure 1 represents a ski boot seen from the outside.
• The figure 2 shows the previous shoe seen from the inside.
• The figure 3 is an explanatory curve of the invention.
• The Figures 4 to 7 illustrate different embodiments of an insert.
• The figure 8 shows a first mode of construction of a heating machine which is not part of the present invention and which is given for information.
• The Figures 9 and 10 relate to another mode of construction of a heating machine which is not part of the present invention and which is given for information purposes.

The Figures 1 and 2 represent a shoe 10. In the example shown, the shoe is a ski boot. It could of course be another type of shoe, snowboard shoe, walking shoe, or a shoe whose part of the stem is a rigid shell element (buttress, collar, etc.. .). The shoe conventionally comprises a shell 11 and an inner comfort liner 12 provided for wrapping the foot of a user. The shell comprises a shell bottom 13 surmounted by a collar 14. The collar is connected to the shell bottom by a hinge 15 which is located approximately in the area of the malleoli. On the top of the bottom of the hull and the front of the collar the hull has two sides that can be moved apart to widen its opening to the introduction of the foot into the shoe and can be brought closer with recovery to the closure of the shoe.

The liner 12 is of any suitable type. For example it is made of foam with outer and inner shells of plastic or textile.

The hull is closed by a hook system which is intended to bring one another closer to the sides of the shell at the closure of the shoe. Four brackets 18, 19, 20, 21 are represented in the Figures 1 and 2 , the first two hooks are located at the bottom of the shell, the others at the collar. The number and position of the hooks are not limiting.

Similarly, the construction of the hull and slipper is not limiting, and the shoe could be of the rear entry type or any other type.

The shell 11 is made of a rigid plastic base material, for example polyurethane or polypropylene. In known manner such a base material is of the thermoplastic type and its softening point is relatively high, of the order of 180 ° C. The bottom shell and the collar of a shell can be made of different materials.

According to one characteristic of the invention, at least a portion of the wall of the shell contains an additive which lowers the softening point significantly.

By way of illustration, it has been shown in Figures 1 and 2 dashed lines of hull portions with additive 24, 25a, 25b, 26a, 26b, 27a, 27b and 28. Each of these portions corresponds to an area of the foot which is deemed to be sensitive.

The portion 24 corresponds to the heel, the portions 25a and 25b to the area of the malleolus, the portions 26a, 26b to the scaphoid zone, the portions 27a, 27b in the metatarsal width zone, and the portion 28 in the zone of the toes.

The number, the position and the shape of these portions with additive are not limiting. The shoe could have only part of these portions or conversely have a continuous portion covering several sensitive areas of the foot. One could also have a single portion comprising the entire wall of the shell bottom and / or collar.

In each portion an additive is added to the base material of the shell to lower its softening temperature. Good results have been obtained with an additive known as caprolactone or caprolactane, and in particular with a product known under the trade name "CAPA 6500". It is a high molecular weight linear polyester derived from caprolactone monomer. Other caprolactone-based polymers may also be suitable.

This additive has a melting temperature in an area of 60 to 80 ° C. Mixed with the material of the shell in a proportion of between 3 and 45%, preferably between 10 and 25%, it lowers the softening temperature of the base material of the shell, in particular polyurethane or polypropylene, without altering the significantly the mechanical properties of the hull, in particular its rigidity, and its aesthetics in the normal conditions of use of the shoe.

Other additives may also be suitable provided that they are miscible with the base material of the shell bottom or collar during injection, they have a low melting temperature, preferably less than 100 ° C, and that their presence in the base material significantly lowers its softening temperature.

The figure 3 illustrates the results of tests that were performed with polyurethane as a raw material. In this diagram, the storage modulus expressed in MegaPascals, which characterizes the stiffness of the material as a function of temperature, is plotted on the ordinate. Curve 31 corresponds to the additive alone. We can see that the The stiffness of the material collapses to 70 ° C, which means that the material melts at this temperature.

Curves 32, 33 and 34 respectively correspond to polyurethane without additive, polyurethane with 10% additive, and polyurethane with 25% additive.

The three curves have an almost common start, which means that at ambient temperature the three materials have substantially the same rigidity. For the curves 33 and 34 it is found that the presence of the additive generates around 70 ° C a decrease in rigidity, up to a plateau that is maintained for a few tens of degrees. At this level, the material has softened sufficiently to be able to deform by creep under the effect of relatively low thrust forces.

The elevation of the temperature of the hull up to the temperature of 70 ° C can be supported by the foot of a user, with some precautions, taking into account in particular the insulating effect produced by the liner.

Thus, at this temperature, the material of the shell is able to deform under the effect of the thrust printed by a foot that would be present inside the shoe. The hull thus deforms itself to give volume in an area where the foot would be too tight. Conversely, it can also deform the hull from the outside and shape it to bring it closer to the foot in an area where the foot is not tight enough.

In addition it may be noted that the softening temperature of the portions with additive is much lower than that of the rest of the shoe. Thus, heating portions with additives can be achieved without it having any impact on the rest of the hull.

After this deformation phase, the material regains its original rigidity with the cooling of the portions with additive. As has already been said, this rigidity is of the same order of magnitude as that of the base material of the shell portion to which the insert is assembled. Thus, the presence of the additive does not significantly affect the mechanical properties of the shell.

It should also be noted that the presence of the additive in the portions does not significantly alter the aesthetics of the material in the normal conditions of use of the shoe. The heating and the deformation of the portions do not change the aesthetic aspect of the material either. Thus, the hull retains its original aesthetic appearance. Also heating the inserts of the shell is an operation that can be repeated given the thermoplastic nature of the material.

To make the additive portions of the shell, several techniques can be used. To illustrate this, Figures 4 to 7 show partial views of a shell bottom in section at an insert that forms a portion with additive. In the figure 4 insert 36 is through. It is assembled to the rest of the shell at its periphery, for example as shown, the insert is housed at an opening 37 of the shell bottom. The insert has a peripheral recess 81 which forms a peripheral rim of smaller thickness. Likewise, the opening has a peripheral recess 82 and a rim. Each of the recesses is provided to receive the rim of the other room. The assembly is carried out by any appropriate means. For example, the insert is made by overmolding or by a bi-injection technique. In this case, the assembly is carried out with the injection of the insert. Also it is possible to make an insert separately from the rest of the shell, bring it back into the opening of the shell and assemble it by gluing, welding or any other appropriate means.

According to figure 5 , the assembly of the insert 38 to the rest of the shell is made using rivets 39.

For these through embodiments may be provided a film or other suitable means on the inside of the shell to enhance the seal between the insert and the rest of the shell (not shown in the drawing).

According to figure 6 the insert 40 is non-traversing. The wall of the shell has a recess 41 in which the insert is housed. As previously the insert is assembled in the recess during its production, by counter-molding or with a bi-injection technique. It can also be attached and assembled by gluing, welding or any other means.

In the area of the insert, the residual thickness of the wall of the shell is small enough to follow the deformation of the insert by elasticity.

Instead of being continuous, the wall that forms the bottom of the recess could be discontinuous, for example in the manner of meshes of a net.

For the figure 7 , the outer wall of the insert 42 has a surface relief on all or part of its surface. Any suitable relief is suitable, a geometrically shaped relief of squares or lozenges, or portions of sphere, recessed or protruding.

In these different embodiments, the insert is made of the same basic material as the rest of the shell or a material that has the same rigidity in the conditions of use of the shoe.

The figures 8 , 9 and 10 which are not part of the present invention and are given for information purposes show constructions of heating machines. The machine 45 represented in figure 8 is a simple machine provided for a shoe that has inserts in areas 27a and 27b identified in the Figures 1 and 2 .

The machine 45 comprises a support 46 with two corridors 47 and 48 defined by borders 49, 50, 51. The length and width of the corridors are equal to or greater than the length and width of a large shoe for each corridors can receive a shoe of a pair, regardless of its size in the longitudinal direction which is defined by the sole of the shoe.

The support 46 contains a hot air generator. This generator is of a known type, it comprises a source of hot air, for example a heating resistor, and a ventilation. Optionally it is possible to use an external hot air generator which is connected to the support. The borders of the corridors have nozzles which are located two by two on each side of the longitudinal direction defined by the shoe sole and opening opposite vis-à-vis the interior of the corridor. Only the nozzles 52 and 53 are visible in the figure 8 . The nozzles are connected to the furnace, for example by means of ducts which are housed in the curbs.

The nozzles are provided to diffuse towards the shoe hot air from the generator. Optionally one can provide a stop 56, 57 at the bottom of each lane. The position of the stop is established according to the size of the shoe so that the portions to be deformed are well opposite a nozzle. The temperature of the air which is diffused by the nozzles is sufficient so that the wall of the hull reaches its softening temperature after a few minutes. For example, the air temperature is 120 ° C +/- 10 ° C. This temperature is higher than the softening temperature of the inserts, but it remains lower than the softening temperature of the rest of the shell. The heating of the portions does not affect the rest of the hull. The temperature of the air could be lower, if we accept that the heating time is more important.

To deform the shoe, the procedure is as follows. The shoes are placed on the support, the hot air is diffused by the nozzles during about ten minutes. Once the softening temperature is reached, the user introduces his feet into the shoes. The wall of the hull then deforms itself under the pressure it receives from the foot. The hull is then allowed to cool to its original rigidity. Given that the softening temperature is relatively low, the skier can also introduce the feet in the shoes from the beginning of heating.

To deform other areas of the shoes could be provided other nozzles next to other portions with additive of the shoe. Optionally we can enhance the borders to accommodate nozzles that would be for example at the height of the malleolus or collar of the shoe. If the machine has several nozzles, one can provide for each of the nozzles a shutter so as to select the nozzles through which the hot air will be diffused.

The Figures 9 and 10 relate to another mode of construction of a heating machine. This machine is also intended to ensure the shaping of the liner, as described in the patent application FR2739760 quoted in the preamble. For this purpose, the machine has a support 76 which is provided to receive the two shoes 77 and 78 of a pair in an inverted position, the shoe soles being oriented parallel. A hot air generator is located in the support 76, or is connected thereto. Conduits 59 and 60 channel hot air into the boot liner. A pipe 62 channels the hot air to nozzles 64, 65, 66 and 67 which are situated in pairs on each side of the longitudinal direction defined by the shoe sole, and which open opposite level of the zones 27a and 27b of the shoes. According to the illustrated embodiment, the nozzles are located at the ends of the branches of a manifold 70 which is connected to the pipe 62. The manifold 70 is connected to the pipe 62 by a hinge, and it is operated by a lever 71 which allows to position the nozzles according to the shoe size. The branches of the manifold can be telescopic to adjust the position of the nozzles precisely.

The heating machine has a similar operation as previously described. The hot air is sent inside the liner and towards the outer wall of the shoe shell. After about ten minutes, the shoes are removed from the support, and the user introduces the feet in the slippers. Simultaneously, the inner volume of the liner and the volume of the shell adapt to the feet of the user.

As in the previous case can be provided other nozzles for other portions with additive of the shoe and shutters to select the active nozzles.

Other heating modes may also be suitable. Thus, infrared resistors can be used to heat the inserts of the shell from the outside. Also we can drown resistors in the inserts or bring them back by screen printing. It is also possible to heat the inserts by induction on a metal mesh which is present in the insert. Other techniques can be used, a halogen lamp, a heated silicone pad, hot water, steam.

Naturally, the present description is given only as an indication, and one could adopt other implementations of the invention without departing from the scope thereof.

In particular, the invention is not limited to the field of ski boots, it also applies to all shoes that have an outer shell of plastic and any shoe whose stem comprises a rigid shell element, such as buttress or necklace.

Claims (6)

1. Boot comprising a shell (11), or a shell element, made of a rigid base material chosen from among polyurethane and polypropylene, characterized in that at least in a local portion of the shell (24, 25a, 25b, 26a, 26b, 27a, 27b, 28), or of the shell element, the material of the shell encloses a caprolactone-based polymer, in a proportion between 3% and 45%, preferably 10% to 25%.
2. Boot according to Claim 1, characterized in that a portion with additive (24, 25a, 25b, 26a, 26b, 27a, 27b, 28) is formed by an insert (36, 38, 40, 42) whose base material has the same rigidity as the base material of the shell part onto which it is assembled, and which encloses said additive.
3. Boot according to Claim 2, characterized in that the insert is made of the same base material as the shell part onto which it is assembled.
4. Boot according to Claim 2, characterized in that the insert (36, 38) passes the whole way through.
5. Boot according to Claim 2, characterized in that the insert (40) does not pass the whole way through and that it is housed in a recess (41) in the wall of the shell.
6. Boot according to Claim 2, characterized in that the insert (42) has a superficial relief on its outer face.

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