Method of producing a sole / tread for footwear and sole / tread for footwear produced by the method

Abstract

The present invention relates to a method for producing a functional sole for footwear, which allows to make soles / footings suitable for any type of footwear, with any shape and thickness, and which is characterized by high wear resistance, long durability and high and stable performance in all weather conditions, completely and easily customizable in terms of aesthetics.

Description

[0001] Summary of the Invention

[0002] This invention relates to a method for producing functional soles for footwear, which allows for the preparation of soles / treads suitable for any type of footwear, having any shape and thickness, and is characterized by high abrasion resistance, long durability, and high and stable performance under all weather conditions, as well as being aesthetically completely and easily customizable. Technical Background

[0003] Footwear typically consists of a sole (the lower portion, which contacts the ground on one side and the sole of the foot on the other) and an upper (the upper portion). Specifically, the sole is made using one or more abrasion-resistant materials that also possess anti-slip properties, such as cured rubber. This lower portion of the footwear can be composed of a single element or multiple elements assembled together, and / or a single material or a combination of materials. Particularly important, for example, is that the portion in direct contact with the ground (also known as the tread) is particularly durable, possesses an appropriate level of grip, and / or has a particular aesthetic appeal. In this case, additional elements constituting the tread may be present, either continuously along the entire length of the sole or placed only at specific points to enhance these properties. Furthermore, to improve cushioning and foot comfort and stability in any type of shoe (from athletic shoes, through fashion shoes, to safety shoes), a midsole made of shock-absorbing material (typically based on foam polymers such as polyurethane) can be integrated into the tread in the upper portion that contacts the sole and upper.

[0004] Depending on the type of footwear being manufactured and the performance requirements, soles are designed and produced using different materials and blends to optimally meet the needs of specific footwear types. For example, shoes designed for sports (such as running) must have soles that are abrasion-resistant, slip-resistant, cushioned, and as lightweight as possible; on the other hand, the soles of safety work shoes must prioritize the following capabilities: protecting the foot from any debris on the ground, ensuring stability on uneven surfaces, and providing a high coefficient of friction to prevent slipping, while keeping the weight under control; and on the other hand, the most important functions of the soles of orthopedic shoes are to ensure stability during movement and high grip on any surface, as well as to provide a high level of comfort.

[0005] To meet diverse needs, several materials are currently known and used for manufacturing shoe soles / treads. Among the most well-known materials are, for example, cured rubber, ethylene-vinyl acetate (EVA), polyurethane (PU), polypropylene (PP), or polystyrene (PS). Each material has specific characteristics and, depending on the most desired and / or required properties, can be processed using different machines and different production processes.

[0006] To date, there is indeed no single material or manufacturing process that can produce a "perfect" sole that embodies all the desirable features for every type of application.

[0007] In addition to the different materials that make up the sole, as previously mentioned, it can be useful to add other elements to the main sole at the bottom (e.g., rubber reinforcements at the toe and heel to improve abrasion resistance) or at the top (e.g., a polyurethane foam midsole to increase cushioning). These additional elements are typically “glued” to the main sole in successive steps using chemical compounds and / or applying pressure and high temperatures, causing the different materials to adhere to each other.

[0008] The manufacturing process for shoe soles varies depending on the materials / blends used. Typically, a mold is used to insert materials that may be in a solid or viscous state, and then thermoforming is performed by applying specific temperatures and pressures. If the sole consists of multiple components, they should be glued together after production or added in subsequent steps of the process.

[0009] However, the various materials used today have limited applications. For example, cured rubber is often used to manufacture soles / treads with good grip values ​​but at a disadvantage in terms of weight; furthermore, cured rubber wears out relatively quickly and, in particular, retains its performance only within a narrow temperature range. In contrast, soles with polyurethane treads offer good durability but have reduced grip on certain types of surfaces, especially at low temperatures.

[0010] Therefore, there remains a need for a method for producing shoe soles / uppers that allows for the preparation of soles using a single blend and a single type of method, possessing all the desired characteristics for any application and under any temperature conditions. In other words, there remains a need for shoe soles / uppers that can simultaneously achieve lightweight, durable, slip-resistant (high grip), stable performance over a wide temperature range, and extensive and easy aesthetic customization through the application of a single technology.

[0011] Purpose of the invention

[0012] The object of this invention is to provide a method for producing functional soles for footwear, which allows for the preparation of soles / treads suitable for any purpose and any type of footwear, and is characterized by high abrasion resistance, long durability, stable performance under all weather conditions, and easy customization from an aesthetic point of view without being limited by color and / or design.

[0013] Another object of the present invention is to provide a sole / tread for footwear produced according to the method of the present invention.

[0014] Another object of the present invention is the use of thermosetting polymers produced according to the method of the present invention for the production of soles / upper surfaces for footwear.

[0015] These and other objectives are achieved through the subject matter of the present invention, which relates to a method for producing soles / uppers for footwear.

[0016] Brief description of the attached figures

[0017] Figure 1 : An example drawing of a type of flat sole / tread (10); (a) front view, (a') rear view, (b) and (b') side views, (c) bottom view, (d) intermediate cross-section view perpendicular to the ground, in which the missing side rims depicted in (d') and (d'') are highlighted.

[0018] Figure 2 : An example of a type of “box-shaped” sole / tread (20); (A) front view, (A') rear view, (B) and (B') side views, (C) bottom view, (D) mid-section view perpendicular to the ground, in which the presence of the side rims depicted by (D') and (D'') is highlighted. Summary of the Invention

[0019] The object of the present invention is a method for producing soles / upper surfaces for footwear, the method comprising using at least one thermosetting polymer and a vacuum molding step in a heated mold.

[0020] The term "sole" generally and as a whole refers to the part of footwear (also called shoes), which constitutes the lower part, particularly the part that contacts the ground on one side and the upper and sole of the foot on the other.

[0021] The term "tread" is intended to specifically refer to the part of the shoe sole that is in direct contact with the ground. When the sole and tread are both composed of a single element that simultaneously contacts the ground in their lower portion and the upper portion in their upper portion, the sole and tread can overlap each other.

[0022] This invention relates to a method for producing any type of functional sole, which is understood to be a sole / tread that ensures specific performance for its intended application, such as, but not limited to, sports (running, hiking, rock climbing, basketball, tennis, etc.), work (industrial, fire fighting, construction, etc.), military (combat boots, police, special forces, etc.), fashion (luxury goods, lifestyle, children's, etc.) and orthopedic shoes.

[0023] The method according to the invention also enables the production of any type of tread that can be combined with additional materials to form a sole that integrally meets the above requirements.

[0024] The term "thermosetting polymer" is intended to refer to those polymers that, under suitable temperature and pressure conditions and / or in the presence of a specific catalyst, transform into solid, insoluble, and infusible materials. This transformation occurs as a result of a crosslinking reaction, i.e., the formation of strong bonds (covalent or ionic) between the individual polymer chains at the level of reactive functional groups. Among the most well-known and widely used thermosetting polymers are members of the polyurethane (PU), synthetic rubber, and epoxy resin families. Thermoplastic polymers are not used in the method of this invention. In other words, the use of thermosetting polymers in this method is necessary to achieve the advantages of the invention described herein.

[0025] Advantageously, the material obtained at the end of the method according to the invention is a dense material. The term "dense material" herein means a material in which no air is contained, i.e., no air is introduced during its production process. In other words, the sole / tread obtained by the method of the invention does not contain foam or foam material.

[0026] The at least one thermosetting polymer that can be used in the present invention is preferably selected from members of the polyurethane family (alone or in mixtures thereof), and preferably, it is a mixture of polyurethanes produced by the condensation of at least one isocyanate with at least one polyol composed of polyester (polyester polyurethane) and the condensation of at least one isocyanate with at least one polyol composed of polyether (polyether polyurethane).

[0027] According to a preferred aspect of the invention, the at least one isocyanate is preferably 4,4'-diphenylmethane diisocyanate (CAS 101-68-8).

[0028] According to another preferred aspect of the invention, the at least one polyol is selected from poly(tetrahydrofuran) (CAS25190-06-1), poly1,2-propanediol (CAS 9042-19-7), 1,4-butanediol (CAS 110-63-4), and mixtures thereof.

[0029] According to another preferred aspect of the invention, the at least one polyol is selected from poly(tetrahydrofuran) (CAS25190-06-1), poly1,2-propanediol (CAS 9042-19-7), 1,4-butanediol (CAS 110-63-4), polyol polyesters having CAS number 27925-07-1, and mixtures thereof.

[0030] In the embodiments, the at least one polyol composed of polyether is selected from poly(tetrahydrofuran) (CAS 25190-06-1), poly1,2-propanediol (CAS 9042-19-7), and mixtures thereof.

[0031] In the embodiments, the at least one polyol composed of polyester is preferably a polyol polyester (poly(neoprene adipate)) having CAS number CAS 27925-07-1.

[0032] According to an aspect of the invention, the polyol composed of polyester and the polyol composed of polyether can be mixed with each other in a variable ratio to obtain a “starting” mixture, the “starting” mixture may also contain at least one isocyanate.

[0033] For example, the variable ratio between a polyol composed of polyester and a polyol composed of polyether is of the type 1:1 or 1:2.

[0034] For example, the “starting” mixture can be an M1 type “starting” mixture as further described below, and an M2 type “starting” mixture as further described below. The M1 and M2 “starting” mixtures can be used in the method according to the invention, for example, according to a variable M1:M2 ratio between 90:10 and 70:30, preferably an M1:M2 ratio of 80:20. In other embodiments, the M1 and M2 “starting” mixtures can be used in the method according to the invention according to a variable M1:M2 ratio between 15:85 and 25:75, for example, an M1:M2 ratio of 20:80. For example, when the M1 “starting” mixture contains at least one polyol made of polyether and the M2 “starting” mixture contains at least one polyol made of polyester, the M1 and M2 “starting” mixtures can be used at an M1:M2 ratio between 15:85 and 25:75, such as an M1:M2 ratio of 20:80.

[0035] The method for producing shoe soles / treads according to the present invention includes the following steps:

[0036] a) Forming a blend for preparing at least one thermosetting polymer selected from members of the polyurethane family, preferably a thermosetting polymer consisting of a mixture of the following:

[0037] - A polyester polyurethane produced by the condensation of at least one isocyanate and at least one polyol composed of a polyester, and

[0038] - A polyether polyurethane produced by the condensation of at least one isocyanate with at least one polyol composed of a polyether.

[0039] b) Mix the blend from step (a) with an accurate weighed amount of a suitable catalyst;

[0040] c) The blend, mixed with the catalyst from step (b), is introduced into a heated closed mold and molded therein under vacuum conditions; and optionally,

[0041] d) Combine the fabric, plastic, or cellulose film with the pattern you wish to combine with the sole / tread.

[0042] According to an aspect of the invention, the formation of a blend of at least one thermosetting liquid polymer in step (a) is accomplished by directly using commercially available polymers or by blending them together and / or adding specific additives known to those skilled in the art, which improve the technical characteristics of the polymer itself (e.g., dielectric or electrical conductivity characteristics). Non-limiting examples of additives that may be added are the compounds [pentaerythritol tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (CAS 6683-19-7) and Tns-(2,4-di-tert-butyl)phosphite (CAS 31570-04-4).

[0043] According to a preferred aspect of the invention, the accurately weighed suitable catalyst in step (b) is selected from the amine catalyst category, for example, but not limited to, amine 1,4-diazabicyclooctane (CAS 280-57-9). The catalyst, appropriately selected according to the knowledge of those skilled in the art, is added to the mixture of step (a) in an amount between 0.1% and 0.4% by weight relative to the weight of the mixture, preferably between 0.1% and 0.3% by weight. The addition is carried out using equipment equipped with a volumetric metering / mixing device, which simultaneously meteres the appropriate amount of catalyst and thoroughly blends it with the polymer from step (a). The blending and metering of the polymer and / or polymer blend with the catalyst are performed simultaneously. The metering of the catalyst and its blending with the polymer and / or polymer blend are performed shortly before the material is introduced into the mold. The metering of the catalyst and its blending with the polymer and / or polymer blend must be performed no more than 5 minutes, preferably 1 minute, and most preferably 10 seconds before the material is introduced into the mold.

[0044] According to the present invention, the catalyst-containing blend obtained in step (b) is introduced into a heated mold in two steps: the first step includes introducing the mixture from step (b) by gravity through a hole (pour channel) present in the upper part of the closed mold; the second step includes activating a vacuum in the mold cavity, thereby allowing the blend from step (b) to reach all points in the mold cavity, regardless of the desired shape and thickness.

[0045] According to an aspect of the invention, the viscosity of the blend poured into the mold is about 2,000 Pa. s (kinematic viscosity measured at 20°C).

[0046] According to a preferred aspect, the mold is maintained at a temperature between 70°C and 100°C, preferably between 70°C and 80°C, and under a vacuum of about -0.9 bar for 10 minutes.

[0047] Advantageously, the molding process is carried out under vacuum conditions, thereby preventing the introduction of air into the blend mixed with the catalyst during the process and enabling the production of soles / treads with dense materials.

[0048] In the method of the present invention, the mold used for molding the sole / tread is preferably made of aluminum alloy, obtained by casting and subsequent machining, or directly machined from a solid aluminum block. Furthermore, the mold is closed, i.e., it consists of two parts that overlap to leave an empty internal cavity, which will be filled with the blend from step (b) and have the final shape of the sole / tread to be obtained.

[0049] The mold is equipped with one or more holes in the upper part (mold cover) that allow the introduction of the blend of step (b) and one or more devices that are capable of generating the desired vacuum value in the cavity at the appropriate time.

[0050] The mold is also equipped with a gasket arrangement that is positioned between the two main parts that make up the mold (the upper part, i.e., the mold cover, and the lower part), and the gasket arrangement is designed to keep the blend of step (b) within the cavity when a vacuum is applied to the mold.

[0051] The sole produced by the method according to the invention, due to its high performance in abrasion resistance and subsequent long durability, lightweight, high grip and stable performance over a wide temperature range, can directly form the tread of the sole, that is, the part in contact with the ground.

[0052] In particular, the soles / treads produced by the method of the present invention are characterized by:

[0053] - Measured at 23°C and stable between +6°C and +50°C (Test Method GB / T 531.1-2008), with a hardness between 60 and 70 Shore A;

[0054] - Very high abrasion resistance, with a value up to 15 mm. 3 More typically at 20 mm 3 With 40 mm 3 Between (Test method GB / T9867-2008 Method A);

[0055] - Density is 0.990 g / cm³ 3 With 1.100 g / cm 3 Between (Test method GB / T1033.1-2008 Method A);

[0056] - The coefficient of friction on dry surfaces ranges from 0.99 to 1.35 and on wet surfaces from 0.45 to 0.75 (Test method GB / T 4100-2015 Appendix M).

[0057] - Very high oil resistance, between 0.1% and 3% (test method UL 50E-2020, clause 8.13.4 and ASTM D471-16).

[0058] Depending on the blend, all previously listed characteristics, except for hardness (which remains stable between +6°C and +50°C as described), remain stable and / or show minimal variation within temperature ranges of -20°C to +40°C, or +6°C to +60°C, or -40°C to +40°C. Therefore, these characteristics / properties remain stable in temperature ranges from as low as 54°C (+6°C to +60°C) to over 80°C (-40°C to +40°C).

[0059] Furthermore, the soles / treads produced according to the present invention can have very different thicknesses, in particular, the sole / tread thicknesses that can be obtained are from 0.6 mm to 10 mm; typically from 0.6 mm to 5 mm.

[0060] An additional, extremely important, and advantageous improvement resulting from the method according to the invention is that, unless intentionally colored or customized with a specific pattern, the sole / tread obtained by the method is completely transparent, colorless, and odorless, unlike any other sole obtained by other techniques and materials.

[0061] Another object of the present invention is to produce a sole / tread characterized by the properties listed above by means of the method according to the invention. Furthermore, the sole / tread produced by means of the method according to the invention comprises a dense material and does not contain thermoplastic polymers and / or foam. According to another aspect, the sole / tread produced by means of the method according to the invention does not have cushioning features. Preferably, the sole / tread produced by means of the method according to the invention is a tread, i.e., the portion of the sole (or shoe) that directly contacts the ground.

[0062] Another object of the present invention is to use, in the method of producing shoe soles according to the invention, a thermosetting liquid polymer selected from members of the polyurethane family (alone or in mixtures of each other), preferably a polyurethane mixture produced by the condensation of isocyanate with a polyol composed of polyester (polyester polyurethane) or a polyol composed of polyether (polyether polyurethane).

[0063] The method of this invention can produce soles / uppers with various shapes, sizes, and thicknesses. Therefore, flat and smooth soles covering the entire lower portion of footwear can be obtained. Figure 1 ), and smaller portions that may only occupy certain sections of the lower part of the footwear for aesthetic and / or functional reasons (e.g., heel and / or toe and / or midsole and / or toe cap). Furthermore, according to another aspect of the invention, so-called "box-shaped" soles / studs can also be produced. Figure 2 It has a raised rim ( Figure 2 The segments, represented by the letters (D') and (D''), form a three-dimensional container that can hold the midsole.

[0064] In this case, while maintaining a very small sole / tread thickness in the lower part and the wall, and typically a wall thickness between 0.6 mm and 3 mm, it is possible to produce sidewalls that are even very extended in height. Figure 2 The "box-shaped" sole (described by the letters (D') and (D'')) has a height of 1 mm to 70 mm.

[0065] According to a preferred aspect of the invention, in cases where the sole produced by the method according to the invention needs to be bonded to another element constituting the lower part of the footwear, such as when the sole only constitutes part of the tread or when it has a “box-like” structure that must be filled with polyurethane foam capable of forming a midsole, the sole does not need to be pretreated with chemical reagents and coated with adhesive before receiving the polyurethane formed by foaming the midsole in a subsequent stage.

[0066] In practice, the soles produced according to the method of the invention can be inserted into a mold as is, forming a second element (e.g., a polyurethane foam midsole) that constitutes another lower part of the footwear. This second element can be formed directly on top of the mold, resulting in perfect adhesion / cohesion between the two parts without the need for further chemical treatments, components, and / or adhesives. Alternatively, by replacing the upper portion of the mold with a suitably shaped mold cap, the lower portion of the same mold used to produce the soles / treads according to the invention can be used to form the second element. This also ensures significant cost savings, as there is no longer a need to produce a second dedicated mold set for the midsole.

[0067] This aspect constitutes an additional advantage of the soles / upper surfaces produced according to the present invention, as it allows for the avoidance of chemical treatments, adhesives and / or the deposition of other components, which is necessary in the case of shoes with foamed polyurethane midsoles and cured rubber soles / upper surfaces, which must be forcibly and preventively prepared by mild and specialized processes with non-neutral and potentially even high environmental impacts.

[0068] The method according to the present invention has many advantages compared to methods described and discovered in the prior art. The resulting functional soles / treads are indeed characterized by better properties and performance; in particular, compared to the most common and used cured rubber functional soles on the market today, they have:

[0069] - The ability to produce with a wide range of thicknesses, from very small thicknesses (starting from a fraction of a millimeter, such as the minimum thickness of 0.6 mm) to thicknesses up to 8-10 mm;

[0070] - Low density, 7%-9% lower than cured rubber;

[0071] - The combination of low density, very high abrasion resistance, and the possibility of very thin thickness allows for the production of soles that are aesthetically pleasing like rubber soles but 60% to 80% lighter.

[0072] - High durability, up to three times that of cured rubber soles using more durable blends (the abrasion resistance of soles produced by the method according to the invention is typically 20 mm). 3 [Measured according to GB / T9867-2008 Test Method A], the abrasion resistance is significantly lower than that obtained in the case of cured rubber soles produced by compression, which provides abrasion resistance from 60 mm. 3 (starting values ​​and above);

[0073] - Extremely high grip, equal to or better than the best rubber blends on both wet and dry surfaces (coefficient of friction from 0.99 to 1.35 on dry surfaces and from 0.45 to 0.75 on wet surfaces [GB / T4100-2015 Test Method Appendix M]).

[0074] - Stable performance over a wide temperature range, as previously described, is evaluated by performing all characterization tests at various temperatures and recording the time it takes for the measured values ​​to differ from those recorded under room temperature / standard temperature conditions;

[0075] - Due to the natural transparency of the soles / treads produced according to the method of the invention (which allows them to be seen as "glass") and the possibility of integrating colored patterns into their whole, aesthetic customization can be easy, unlimited, unrestricted in shape and color, and can be changed quickly. The colored patterns can be easily embedded into the soles / treads by using, for example, fabrics, plastics, or cellulose films with the patterns to be integrated (optional step (d) of the method according to the invention).

[0076] For illustrative and non-limiting purposes, the characteristics and advantages of the method according to the invention will be explained through the following experimental section.

[0077] Experimental Section

[0078] Example 1 - Production of flat shoe soles / treads according to the present invention ( Figure 1 )

[0079] Prepare a mixture of components M1 and M2 as described in Tables 1 and 2 in a ratio of 80:20 (step (a)).

[0080] Table 1: Qualitative / Quantitative Composition of M1

[0081]

[0082] Table 2: Qualitative / Quantitative Composition of M2

[0083]

[0084] In parallel, a closed mold is prepared, connected to a vacuum connector, and heated to 80°C.

[0085] The mixture of the two polyurethanes prepared in step (a) is immediately and rapidly fed into a device for metering and blending the catalyst 1,4-diazabicyclooctane (CAS 280-57-9) at a ratio of 0.4% by weight relative to the weight of the polyurethane mixture (step (b)).

[0086] Immediately pour the mixture, to which the catalyst from step (b) has been added, into the casting channel / gate of the preheated mold, being careful to pour 50% more than the final sole / tread volume to ensure complete filling of the mold (step (c)).

[0087] Once the pouring step is complete, wait a few seconds (preferably tens of seconds, e.g., 30 seconds), and then apply a vacuum of -0.9 bar to the mold. Depending on the size of the sole / tread, allow the polymerization reaction to proceed for between 500 and 750 seconds; for a size 42 sole, typically about 600 seconds.

[0088] Once the time required for complete polymerization has elapsed, the vacuum is removed and the mold is opened. The sole, now solid, is then manually removed and sent for routine finishing operations (deburring, polishing, and packaging).

[0089] Example 2 - Production of a shoe sole including a midsole according to the present invention

[0090] To produce the sole, including the midsole, follow all the steps previously described in Example 1 until the mold is opened; however, in this case, the solid sole / tread is not then removed.

[0091] In fact, once the mold is opened, the "box-shaped" sole / tread (20) remains in the lower part of the mold itself, and the mold heating system is removed.

[0092] Simultaneously, polyurethane (PU) is blended using a suitable catalyst. Next, the catalyzed PU is poured into a "box-shaped" shoe sole to contain it, thus forming the lower part of the "mold".

[0093] The mold is then closed on top with a mold cap having a suitably shaped cavity to allow the polyurethane to expand and form the midsole, which will contact the lower part of the upper at its top.

[0094] The mold is closed for a sufficient amount of time to allow the polyurethane foam to expand and crosslink, depending on the type and quantity of the foam. After that, the mold is opened and the complete sole with the midsole is manually pulled out.

[0095] The resulting composite soles are then sent for routine finishing processes (deburring, polishing, and packaging).

[0096] Example 3 - Production of shoe soles / treads according to the present invention

[0097] Prepare a mixture of components M1 and M2 as described in Tables 1 and 2 above in a ratio of 75:25 (step (a)).

[0098] Antistatic and conductive additives are added to give the final product a resistance between 100 kOhm and 35 MOhm.

[0099] Perform the operation as described in Example 1 or 2 above to obtain a flat sole / tread (10) or a "box-shaped" sole / tread (20) according to the invention.

[0100] Example 4 - Production of flat shoe soles / treads according to the present invention

[0101] Prepare a mixture of components M1 and M2 as described in Tables 3 and 4 in a ratio of 20:80 (step (a)).

[0102] Other usable M1:M2 ratios are, for example, 15:85 and 25:75.

[0103] Table 3: Qualitative / Quantitative Composition of M1

[0104]

[0105] Table 4: Qualitative / Quantitative Composition of M2

[0106]

[0107] Once components M1 and M2 are mixed, the process is carried out as described above for Example 1 or 2 to obtain a flat sole / tread (10) or a “box-shaped” sole / tread (20) according to the invention.

Claims

1. A method for producing soles / uppers for footwear, Its characteristics include the following steps: a) Forming a blend for preparing at least one thermosetting polymer selected from members of the polyurethane family, preferably a thermosetting polymer consisting of a mixture of the following: - A polyester polyurethane produced by the condensation of at least one isocyanate and at least one polyol composed of a polyester, and - A polyether polyurethane produced by the condensation of at least one isocyanate with at least one polyol composed of a polyether. b) Mix the blend from step (a) with an accurate weighed amount of a suitable catalyst; c) The blend, which is mixed with the catalyst of step (b), is introduced into a heated closed mold and molded therein under vacuum conditions; And optionally, d) Combine the fabric, plastic, or cellulose film with the pattern you wish to combine with the sole / tread.

2. The method according to claim 1, characterized in that, The catalyst in step (b) is an amine catalyst, preferably 1,4-diazabicyclooctane (CAS 280-57-9).

3. The method according to claim 1 or 2, characterized in that, The catalyst in step (b) is added in an amount between 0.1% and 0.4% by weight relative to the polymer mixture, preferably in an amount between 0.1% and 0.3% by weight.

4. The method according to any one of the preceding claims, characterized in that, The vacuum conditions in step (c) consist of a pressure of -0.9 bar applied in the closed mold.

5. The method according to any one of the preceding claims, characterized in that, The at least one isocyanate in step (a) is 4,4'-diphenylmethane diisocyanate (CAS 101-68-8).

6. The method according to any one of the preceding claims, characterized in that, The at least one polyol in step (a) is selected from poly(tetrahydrofuran) (CAS 25190-06-1), poly1,2-propanediol (CAS 9042-19-7), 1,4-butanediol (CAS 110-63-4), polyol polyesters having CAS number 27925-07-1, and mixtures thereof.

7. A sole / tread for footwear produced according to the method of claim 1, characterized in that: - Measured at 23°C (Test Method GB / T 531.1-2008), the hardness is between 60 and 70 Shore A; - Abrasion resistance up to 15 mm 3 Preferably at 20 mm 3 With 40 mm 3 Between (Test method GB / T9867-2008 Method A); - Density is 0.990 g / cm³ 3 With 1.100 g / cm 3 Between (Test method GB / T1033.1-2008 Method A); - The coefficient of friction on dry surfaces ranges from 0.99 to 1.35 and on wet surfaces from 0.45 to 0.75 (Test method GB / T 4100-2015 Appendix M). - Oil resistance is between 0.1% and 3% (test method UL 50E-2020, clause 8.13.4 and ASTM D471-16).

8. A flat sole / tread (10) for footwear produced according to the method of claim 1, characterized in that, It has a thickness of 0.6 mm to 5 mm.

9. A "box-shaped" sole / tread (20) for footwear produced according to the method of claim 1, characterized in that, The lower portion has a thickness of 0.6 mm to 5 mm and a rim ((D') and (D'')) of 0.6 mm to 3 mm, the rim rising laterally to a height of 1 mm to 70 mm.

10. Use of a mixture for producing a functional sole for footwear according to the method of claim 1, said mixture having the following components: - A polyester polyurethane produced by the condensation of at least one isocyanate and at least one polyol composed of a polyester, and - A polyether polyurethane produced by the condensation of at least one isocyanate with at least one polyol composed of a polyether.

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