Method for providing bottoms of footwear

Abstract

A method for providing bottoms (100) of footwear, the bottoms being of the type comprising an outer shell (101) and a core (102) for filling the shell; the method comprises the following steps: a. preparing a mixture (2) which comprises a polymeric material in the form of expanded granules (3) and an adhesive (4), b. placing the shell in a complementarily-shaped cavity provided in a first mold part (7), c. filling the shell with the mixture, d. applying a second mold part (8) onto the first mold part, enclosing the cavity in which the shell is arranged, e. heating either or both of the first mold part and the second mold part, and as a consequence the mixture in the shell, f. cooling either or both of the first mold part and the second mold part, and as a consequence the mixture in the shell, at least until the complete combining of the mixture with the shell, with consequent obtaining of the bottom of the shoe, comprising the outer shell and the core constituted by the mixture, g. extracting the bottom from the cavity.

Description

[0001] METHOD FOR PROVIDING BOTTOMS OF FOOTWEAR

[0002] The present invention relates to a method for providing bottoms of footwear.

[0003] As is known, in every shoe the bottom is that part that is directly interposed between the foot (enveloped by the upper) and the ground: as such, it plays a crucial role in ensuring adequate comfort for the user, in that it has to adequately cushion contact with the ground while the weight of the user bears down on it.

[0004] In such context, and in particular in sports footwear, the use is widespread of the material known as “eTPU” for filling these bottoms.

[0005] This material is composed of an aggregate of granules, which are obtained by expanding particles of thermoplastic polyurethane (TPU), until cells or bubbles are formed around minuscule air sacs.

[0006] This material has been found to be even more appreciated than other polymeric materials in the form of expanded granules which have long been used in the manufacture of bottoms, because of its superior properties in terms of cushioning, versatility, strength, flexibility and, especially, elastic return.

[0007] Such implementation solution is not however devoid of drawbacks.

[0008] The methods adopted to date in the technique for manufacturing bottoms made or filled with eTPU (or with other polymeric materials in the form of granules) require the use of apparatuses and equipment that is dedicated, voluminous, and very expensive, which inevitably raises the cost of the finished product, making it accessible only to the manufacturing companies with the most resources, and in any case only for large-scale mass production.

[0009] The aim of the present invention is to solve the abovementioned problems, by providing a method for providing bottoms of footwear, in eTPU or other polymeric materials in the form of granules, that can be carried out simply and at low cost. Within this aim, an object of the invention is to provide a method that can be carried out in a practical and versatile manner, without the need for using expensive and cumbersome apparatuses and equipment.

[0010] Another object of the invention is to provide a method that ensures a high reliability of operation.

[0011] Another object of the invention is to provide a method that adopts a technical and structural architecture alternative to those conventional methods.

[0012] Another object of the invention is to provide a method that can be easily implemented starting with elements and materials readily available on the market.

[0013] Another object of the invention is to provide a method that is certain to be safe in use.

[0014] This aim and these and other objects which will become more apparent hereinafter are all achieved by a method according to claim 1.

[0015] Further characteristics and advantages of the invention will become more apparent from the description of a preferred, but not exclusive, embodiment of the method according to the invention, which is illustrated by way of non-limiting example in the accompanying drawings wherein:

[0016] Figure 1 is a block diagram of the method according to the invention;

[0017] Figure 2 is a perspective view of a bottom of a shoe that can be obtained with the method according to the invention;

[0018] Figure 3 is a schematic side view of a machine that can be used to carry out step a. of the method according to the invention;

[0019] Figure 4 is a schematic view of the mixture that can be obtained by carrying out step a. of the method according to the invention;

[0020] Figure 5 is a schematic cross-sectional view of a shell placed in the respective first mold part, in the configuration obtainable by carrying out step b. of the method according to the invention;

[0021] Figure 6 is a schematic cross-sectional view of the shell placed in the respective first mold part and filled with the mixture, in the configuration obtainable by carrying out step c. of the method according to the invention;

[0022] Figure 7 is a schematic cross-sectional view of the second mold part applied on the first mold part of Figure 6, in the configuration obtainable by carrying out step d. of the method according to the invention;

[0023] Figures 8 and 9 show respectively, in the first mold part and second mold part of Figures 6 and 7, the channel systems used to carry out steps e. and f. of the method according to the invention;

[0024] Figure 10 is a schematic view of the bottom of the shoe, as obtainable once extracted from the first mold part, at the end of step g. of the method according to the invention.

[0025] With particular reference to the figures, the reference numeral 1 generally designates a method for providing bottoms 100 of footwear. More precisely, the bottom 100 that can be obtained using the method 1 is of the type that (according to a configuration traditional per se) comprises an outer shell 101 and a core 102 for filling that shell 101.

[0026] The shell 101 defines with its lower wall the sole of the shoe while the core 102 evidently plays a crucial role in conferring the mechanical properties of the bottom 100 (and of the shoe in general), in terms of cushioning capacity, strength, flexibility, elastic return etc.

[0027] The method 1 makes it possible to provide bottoms 100 intended for footwear of any type; likewise, in the preferred application the footwear is a sports shoe, a sneaker, or the like.

[0028] According to the invention, the method 1 first of all entails, in a step a., preparing a mixture 2 which comprises a polymeric material in the form of expanded granules 3 and an adhesive 4. As will become more apparent below, the mixture 2, suitably made up during the method 1, is designed to form the core 102 of the bottom 100.

[0029] In particular, the polymeric material can be chosen from thermoplastic polyurethane (often identified in the sector with the acronym “TPU”), polypropylene (“PP”), polyethylene (“PE”) and polystyrene (“PS”), and preferably (not necessarily) it is indeed thermoplastic polyurethane. In the granular 3 form in which they are employed in the present context, these materials are also identified in the sector as “eTPU”, “ePP”, “ePE”, and “ePS”. The granules 3 (spherical or other shape) are typically constituted by particles of the chosen polymeric material, made to expand until cells or bubbles are formed around minuscule air sacs.

[0030] In any case they are well-known materials, which (like the adhesive 4) can be made available for carrying out the method 1 in any way.

[0031] The function of the adhesive 4, therefore, is to compact and combine the granules 3 and it may be any adhesive, as a function of the specific requirements; in any case, in a possible solution of significant practical but non-limiting interest of the invention, it can be a polyurethane adhesive 4, preferably water-based.

[0032] The mixture 2 obtained at the end of step a. is schematically shown in Figure 4; the adhesive 4 is shown here and in the other Figures as dots purely for graphical convenience, without any intention to limit or even illustrate its actual structure: it can also be a formless and continuous mass.

[0033] Execution of step a. can occur with any instrumentation or plant, in particular using the machines and methods that the person skilled in the art may deem most suitable in order to obtain an adequate (or optimal) homogenization of the mixture 2 of granules 3 and adhesive 4. For example, it is possible to adopt a (horizontal) laboratory mixer 5 (like the one in Figure 3) or the like, in which the mixture 2 is in any case made to swirl continuously, in a vacuum, inside a chamber 6, until the desired homogenization is obtained.

[0034] The duration of step a. (the mixing time) can be freely chosen, on the basis of the mixture 2 that one wants to obtain and of the properties that one wants to confer to the bottom 100 and / or to the shoe. In this regard it should be noted that a short mixing time will result in a mixture 2 in which the adhesive 4 is still at least partially liquid (the granules 3 are still wet with the adhesive 4) and therefore still active, while a longer mixing time will determine the complete solidification of the adhesive 4 and therefore the drying of the granules 3 (the dried adhesive 4 has been completely deposited on the outer surfaces of the granules 3).

[0035] Both possibilities (granules 3 wet with the still-active adhesive 4, and dried granules 3 with the adhesive 4 inactive at ambient temperature) are comprised in the scope of protection claimed herein.

[0036] The composition of the mixture 2 (in terms of percentage of adhesive 4 and of polymeric material in the form of granules 3) may also be any, in particular as a function of the bottom 100 and / or of the footwear that one wants to obtain.

[0037] In a possible solution of significant practical interest, step a. in any case entails preparing a mixture 2 comprising adhesive 4 in a percentage comprised between 5% and 10%, and preferably equal to 8%, where such percentages are referred to the mass of the polymeric material in the form of expanded granules 3.

[0038] It must in any case be reiterated that the values given above are merely for the purposes of example, and may vary, in addition to, as previously noted, as a function of the type of bottom 100 / footwear, also (for example) on the basis of the mixing zone, the mixing type, the ambient humidity or the ambient temperature.

[0039] The method 1 furthermore entails, in a step b., placing the shell 101 (prepared or pre-molded in advance) of the bottom 100 of the shoe in a complementarily-shaped cavity provided in a first mold part 7, for containment, as schematically shown in Figure 5.

[0040] The shell 101 can be made of polymeric material, for example of TPU, or it can be made of another material.

[0041] This first mold part 7 can be made, for example, of metal by way of machining or other, similar technologies, and if there is a particular need, it can also be made as a prototype / by rapid prototyping (for example where cavities and undercut zones are necessary which are difficult to provide by milling using tools). In any case, the possibility is not ruled out of making the first mold part 7 of nonmetallic material.

[0042] The first mold part 7 can be used exclusively for carrying out the method 1 according to the invention, but it can also be the first mold part used, prior to the method 1, for making the shell 101.

[0043] Steps a. and b. can be executed in any chronological order.

[0044] The method 1 furthermore entails, in a step c., filling the shell 101 with the mixture 2 (before or after the shell 101 has been placed in the cavity of the first mold part 7, and preferably after), thus obtaining the condition shown schematically in Figure 6. The amount of mixture 2 used is typically the amount necessary to fill the shell 101 substantially completely, as in the accompanying figures; however, the possibility is not ruled out of carrying out only a partial filling, and more generally the amount of mixture 2 used in step c. may be any, according to the specific requirements and the footwear to be made.

[0045] Subsequently, the method 1 entails, in a step d., applying a second mold part 8 (or cover) on the first mold part 7, enclosing the cavity in which the shell 101 is placed, filled with the mixture 2 (Figure 7). As can clearly be seen in the accompanying figures, typically the mixture 2 fills the shell 101 (and the cavity in the first mold part 7) substantially up to the brim and therefore the second mold part 8 at the end of step d. can be substantially in contact with the mixture 2.

[0046] The second mold part 8 can also be made, for example, of metal by way of machining or other, similar technologies, and if there is a particular need, it can also be made as a prototype / by rapid prototyping (for example where cavities and undercut zones are necessary which are difficult to provide by milling using tools). In any case, the possibility is not ruled out of making the second mold part 8 of nonmetallic material. Subsequently, the method 1 entails, in a step e., heating either or both of the first mold part 7 and the second mold part 8 (and preferably both), in order to obtain as a consequence the heating of the mixture 2 in the shell 101.

[0047] Step e. is prolonged for the desired length of time, with the first mold part 7 and the second mold part 8 mutually coupled as at the end of step d., and with the cavity maintained at a conveniently chosen temperature (which is obtained by heating, which can be done in any manner).

[0048] The duration of step e. and the temperatures imposed can be any, as a function of the bottom 100 to be made, the materials involved and its dimensions; by way of example, for a TPU shell 101 of constant thickness (4mm), length 200mm and width 90mm, a temperature of 80° C can be maintained in the cavity for a length of time of approximately 45 seconds.

[0049] Step e. makes it possible to polymerize (completely or at least partially) the adhesive 4 with the granules 3. In particular, if (as discussed previously) the granules 3 are wet with the still-active adhesive 4, then step e. makes it possible to polymerize the wet mixture 2; if (as also discussed previously) the granules 3 are dry and the adhesive 4 is inactive, then step e. of heating makes it possible to reactivate the adhesive 4 and therefore to obtain the polymerization.

[0050] Subsequently, the method 1 entails, in step f., cooling either or both of the first mold part 7 and the second mold part 8 (and preferably both), so as to also obtain the cooling of the mixture 2 and of the shell 101, at least until the complete combining of the mixture 2 with the shell 101 : effectively, once step f. is complete, the desired bottom 100 of the shoe is obtained, comprising the shell 101 (still in the cavity) and the core 102 constituted by the mixture 2 (polymerized and combined with the shell 101).

[0051] At the end of step f. the shell 101 and the mixture 2 (completely polymerized) are in fact stably and durably combined so as to form a single body (i.e. the bottom 100). The duration of step f. and the temperatures imposed in it can also be any, as a function of the bottom 100 to be made, the materials involved and its dimensions; by way of example, in the above-mentioned TPU shell 101 of constant thickness (4mm), length 200mm and width 90mm, a temperature of 30° C can be maintained in the cavity for a length of time of approximately 45 seconds.

[0052] After the conclusion of step f., the method 1 then entails extracting the bottom 100 from the cavity of the first mold part 7, so as to be able to handle it freely for the subsequent manufacture of the shoe.

[0053] Steps e. and f. can be carried out in any manner.

[0054] In an embodiment of significant practical interest, schematically shown in Figure 8 for the purposes of non-limiting example of the invention, step e. entails introducing a thermo-vector fluid into a heating channel system 9 provided in either or both of the first mold part 7 and the second mold part 8, and preferably in both, so as to heat the mold parts and consequently the mixture 2 in the shell 101.

[0055] With further reference to an embodiment of significant practical interest, schematically shown in Figure 9 for the purposes of non-limiting example of the invention, step f. entails introducing a refrigerant fluid into a cooling channel system 10 provided in either or both of the first mold part 7 and the second mold part 8, and preferably in both, so as to cool the mold parts and consequently the mixture 2 in the shell 101.

[0056] In particular, either or both of the thermo-vector fluid and the refrigerant fluid (and preferably both) can be constituted by water (but may be oil or the like). The thermo- vector fluid can for example be heated by one or more electric resistance heaters while the refrigerant fluid can for example be brought to the desired temperature by way of a thermoregulator and a refrigerator.

[0057] The channel systems 9, 10 can determine undercuts and in precisely such an eventuality, as mentioned previously, it may be preferable to use first mold parts 7 and / or second mold parts 8 made using rapid prototyping.

[0058] It should be noted that in the accompanying drawings the channel systems 9, 10 are shown only in some figures in order to better illustrate their role in the method 1 according to the invention: preferably, and evidently, they will in any case be provided in the first mold part 7 and / or in the second mold part 8 prior to commencing the method 1.

[0059] Usefully, the method 1 can entail, during execution of step e. and / or of step f., applying an overpressure on the (cavity and therefore on the) mixture 2 placed in the shell 101 (or, in other words, raising the surface pressure on the mixture 2). This is for the purpose of favoring the compaction and / or the polymerization of the mixture 2 and the combining of the latter with the shell 101.

[0060] More specifically, the method 1 can entail applying the overpressure by injecting air under pressure, conveyed in at least one channel leading to the cavity.

[0061] Advantageously, the method 1 can also entail, in a step h. after step g., storing the bottom 100 for a predefined period (for example around 12 hours), before using it in the assembly of the footwear.

[0062] The method 1 described previously, intended for the footwear sector, makes it possible to manufacture bottoms 100 of footwear with simple equipment, at low cost and with minimal space occupation; for example, the first mold part 7 and the second mold part 8 can be not much larger than the dimensions of the shell 101, or at most, such as to define an adequate number of cavities, each one in any case of dimensions complementary to those of the shell 101 and therefore of the bottom 100.

[0063] Thus it has been seen that the method according to the invention fully achieves the set aim, in that it makes it possible to obtain bottoms 100 of footwear, made of eTPU or other polymeric materials in the form of granules 3, in a simple manner and at low cost. Indeed, in particular, the method 1 makes it possible to obtain (economically and practically) bottoms 100 filled with eTPU, which as has been seen is particularly appreciated for its mechanical properties and its versatility.

[0064] Precisely because it requires the use of apparatuses and machines of low cost and reduced bulk, the method 1 is not only practical but also versatile: reconfiguration for manufacturing different bottoms 100 can be easily done by modifying the process parameters (times, durations, composition etc.) described up to this point and / or, at most, adopting a different first mold part 7 and / or second mold part 8.

[0065] The simplicity of the method 1 also consists therefore in the fact that it does not require special and expensive machines in order to carry out the filling, making use instead of an adhesive 4 that is easy to source and to use.

[0066] The method 1 according to the invention is further distinguished from conventional methods by its superior productive and commercial sustainability, and the ability to easily and practically recycle the materials used, and a great lightness and flexibility of the bottom 100 that is obtained.

[0067] The simplicity of the method 1 is further assurance of reliability of operation.

[0068] The invention, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements.

[0069] In the embodiments illustrated, individual characteristics shown in relation to specific examples may in reality be substituted with other, different characteristics, existing in other embodiments.

[0070] In practice, the materials employed, as well as the dimensions, may be any according to requirements and to the state of the art.

[0071] Where the technical features mentioned in any claim are followed by reference numerals and / or signs, those reference numerals and / or signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference numerals and / or signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference numerals and / or signs.

Claims

CLAIMS1. A method for providing botoms (100) of footwear, said bottoms (100) being of the type comprising an outer shell (101) and a core (102) for filling the shell (101), characterized in that it comprises the following steps: a. preparing a mixture (2) which comprises a polymeric material in the form of expanded granules (3) and an adhesive (4), b. placing the shell (101) of the bottom (100) of a shoe in a complementarily-shaped cavity provided in a first mold part (7), for containment, c. filling the shell (101) with the mixture (2), d. applying a second mold part (8) onto the first mold part (7), enclosing the cavity in which the shell (101) is arranged, e. heating either or both of the first mold part (7) and the second mold part (8), and as a consequence the mixture (2) in the shell (101), f. cooling either or both of the first mold part (7) and the second mold part (8), and as a consequence the mixture (2) in the shell (101), at least until the complete combining of the mixture (2) with the shell (101), with consequent obtaining of the bottom (100) of the shoe, comprising the outer shell (101) and the core (102) constituted by the mixture (2), g. extracting the sole (100) from the cavity.

2. The method according to claim 1, characterized in that said polymeric material is chosen from thermoplastic polyurethane, polypropylene, polyethylene and polystyrene, and preferably is thermoplastic polyurethane.

3. The method according to claim 1 or 2, characterized in that said adhesive (4) is a polyurethane adhesive (4), preferably water-based.

4. The method according to one or more of the preceding claims, characterized in that said step a. entails preparing a mixture (2) comprising adhesive (4) in a percentage comprised between 5% and 10%, and preferably equal to 8%, said percentages referring to the mass of polymericmaterial in the form of expanded granules (3).

5. The method according to one or more of the preceding claims, characterized in that said step e. entails introducing a thermo-vector fluid into a heating channel system (9) provided in either or both of the first mold part (7) and the second mold part (8), and preferably in both, in order to heat the first mold part (7) and / or the second mold part (8) and consequently the mixture (2) in the shell (101).

6. The method according to one or more of the preceding claims, characterized in that said step f. entails introducing a refrigerant fluid into a cooling channel system (10) provided in either or both of the first mold part (7) and the second mold part (8), and preferably in both, in order to cool the first mold part (7) and / or the second mold part (8) and consequently the mixture (2) in the shell (101).

7. The method according to claim 5 or 6, characterized in that either or both of said thermo-vector fluid and said refrigerant fluid are constituted by water.

8. The method according to one or more of the preceding claims, characterized in that it entails, during the execution of said step e. and / or of said step f., applying an overpressure on the mixture (2) placed in the shell (101).

9. The method according to claim 8, characterized in that it entails applying the overpressure by injecting air under pressure, conveyed in at least one channel leading to the cavity.

10. The method according to one or more of the preceding claims, characterized in that it entails, in a step h. subsequent to said step g., storing the sole (100) for a predefined period, before using it in the assembly of the shoe.

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