Process for the production of and the soles / treads for footwear resulting from said process

Abstract

The present invention relates to a process for the production of technical soles for footwear that allows soles / treads suitable for any type of footwear, of any shape and thickness, to be prepared and characterized by high abrasion resistance, long durability and high and consistent performance in all weather conditions, fully and easily aesthetically customizable.

Description

[0001] PROCESS FOR THE PRODUCTION OF AND THE SOLES / TREADS FOR FOOTWEAR RESULTING FROM SAID PROCESS

[0002] Summary of the invention

[0003] The present invention relates to a process for the production of technical soles for footwear that allows soles / treads suitable for any type of footwear, of any shape and thickness, to be prepared and characterized by high abrasion resistance, long durability and high and consistent performance in all weather conditions, fully and easily aesthetically customizable.

[0004] Technical background

[0005] Footwear is generally constituted by a sole (lower part in contact with the ground on one side and the sole of the foot on the other side) and an upper (upper part). In particular, the sole is made by using one or more materials, such as vulcanized rubber, that are resistant to abrasion and also have non-slip characteristics. This lower part of the footwear may be constituted by a single element or multiple elements assembled together, and / or a single material or multiple materials. In particular, for example, it is important that the part in direct contact with the ground, also referred to as the tread, is particularly durable, has the correct degree of grip and / or has special aesthetic connotations. In this case there may be additional elements that constitute the tread, either continuous along the entire length of the sole or placed only at some specific points to increase said performance. Furthermore, to increase the cushioning capabilities as well as the comfort and stability of the foot, in any type of shoe, from sports shoes to safety shoe via fashion footwear, a midsole, made of a shock-absorbing material, usually based on a foam polymer, for example, polyurethane, may be coupled to the tread at the upper part in contact with the sole of the foot and the upper.

[0006] Depending on the type of footwear to be made and the performance to be met by said footwear, soles are designed and produced with different materials and blends to optimally meet the needs of the specific type of footwear. For example, a shoe designed to be used for sports, such as running, must have a sole that is resistant to the abrasion, having non-slip characteristics, cushioned but also as lightweight as possible; the sole of a safety work shoe, on the other hand, will have to prioritize the ability to protect the foot from any debris on the ground, ensure the stability of the foot on uneven surfaces and provide a high coefficient of friction to prevent slipping, while maintaining, at the same time, a weight that is not too high; soles for orthopedic shoes, on the other hand, will have among their most important functions that of ensuring stability of movement and high grip on any surface, as well as providing a high level of comfort.

[0007] To meet different needs, several materials from which soles / treads may be made are currently known and used. Among the best known ones, we may mention, for example, vulcanized rubber, ethylene- vinyl acetate (EVA), polyurethane (PU), polypropylene (PP) or polystyrene (PS). Each material has specific characteristics and, also depending on the most desired and / or needed performance, may be processed using different machinery and different production processes.

[0008] To date, there is indeed no single material or manufacturing process that may produce the "perfect" sole that embodies all the ideal characteristics for each type of application.

[0009] In addition to the different material which the sole is comprised of, it may be useful, as previously mentioned, to add other elements to the main sole, either at the bottom (for example, a rubber reinforcement at the toe and heel to increase abrasion resistance) or at the top (for example, a polyurethane foam midsole to increase cushioning). Said additional elements are normally "glued" to the main sole by using chemical compounds and / or the application of pressure and high temperatures, in successive steps, so that the different materials adhere to each other.

[0010] The sole production techniques differ depending on the materials / blends used. Generally, molds are used into which the material, which may be in either a solid or viscous state, is inserted, and then thermoformed by application of specific temperatures and pressures. Should the sole be comprised of multiple elements, they should be glued together after production or added at later steps of the process.

[0011] However, the various materials in use today have limited fields of application. For example, vulcanized rubber is usually used to make soles / treads that have good grip value but are disadvantageous in terms of weight; in addition, vulcanized rubber wears out quickly and, above all, maintains its performance only within a narrow temperature range. In contrast, soles that have a polyurethane tread offer good durability but have reduced grip on certain types of surfaces, especially at low temperatures.

[0012] Therefore, there is still a need to have a process for the production of soles / treads that allows soles to be prepared, with a single blend and a single type of process, that have all the desired characteristics for any application and in any temperature condition. In other words, there is still a need to be able to achieve, with the application of a single technology, soles / treads that are at the same time lightweight, durable, with non-slip characteristics (high grip), with consistent performance over a wide temperature range, as well as widely and easily customizable from an aesthetic point of view.

[0013] Objects of the invention

[0014] An object of the present invention is to provide a process for the production of technical soles for footwear that allows soles / treads suitable for any use and any type of footwear to be prepared and which are characterized by high abrasion resistance, long durability, consistent performance in all weather conditions and easily customizable from an aesthetic point of view without limitations on color and / or design.

[0015] Another object of the present invention is to provide a sole / tread for footwear produced according to the process of the present invention.

[0016] Further object of the present invention is the use of thermosetting polymers according to the process of the present invention for the production of soles / treads for footwear.

[0017] These and other objects are achieved by what is the subject matter of the present invention, which relates to a process for the production of soles / treads for footwear.

[0018] Description of the Figures

[0019] Figure 1 : example drawing of a type of flat sole / tread (10); (a) front view, (a1) rear view, (b) and (b1) side views, (c) bottom view, (d) middle section perpendicular to the ground in which the absence of side edges depicted by (d1) and (d") is highlighted.

[0020] Figure 2: example drawing of a type of "box" sole / tread (20); (A) front view, (A1) rear view, (B) and (B1) side views, (C) bottom view, (D) middle section perpendicular to the ground in which the presence of side edges depicted by (D1) and (D") is highlighted.

[0021] Description of the invention

[0022] Object of the present invention is a process for the production of soles / treads for footwear, which provides for the use of at least one thermosetting polymer and the use of a vacuum molding step inside heated molds.

[0023] By the term "sole" is meant, generically and as a whole, the part of the footwear, also referred to as the shoe, which constitutes the lower part, particularly the part in contact with the ground on the one hand and with the upper and the sole of the foot on the other hand.

[0024] By the term “tread” is meant to specifically refer to the portion of the sole in direct contact with the ground. Sole and tread may coincide with each other when they are constituted by a single element that is, at the same time, in contact with the ground in its lower part and with the upper in its upper part.

[0025] The present invention is directed to a process capable of producing any type of technical sole understood as a sole / tread that ensure specific performance for the application for which it is intended, such as for example but not limited to, sports (running, hiking, climbing, basketball, tennis, etc.), work (industry, firefighting, construction, etc.), military (Combat boots, police, special corps, etc.), fashion (luxury, lifestyle, children's, etc.), and orthopedic footwear.

[0026] The process according to the present invention also enables to produce any type of tread that may be coupled to additional materials to form a sole that meets as a whole the above requirements.

[0027] By the term "thermosetting polymers" is meant to refer to those polymers that, under appropriate conditions of temperature, pressure and / or in the presence of particular catalytic substances, are transformed into solid, insoluble and infusible materials. This transformation occurs as a result of cross-linking reactions, that is, the formation of strong bonds (covalent or ionic) between the various polymer chains at the level of reactive functional groups. Among the best-known and most widely used thermosetting polymers, members of the polyurethane (PU), synthetic rubber and epoxy resin families may be mentioned. No thermoplastic polymers are used in the process of the present invention. In other words, the use of thermosetting polymers in the process is essential to achieve the advantages of the invention, described herein.

[0028] Advantageously, the material obtained at the end of the process according to the invention is a compact material. By the term "compact material" is meant herein to refer to a material that does not include air in it, that is, it has not incorporated air during the process for its production. In other words, the sole / tread obtained by the process of the invention does not comprise foams or foamed materials.

[0029] At least one thermosetting polymer that may be used in the present invention is preferably selected from members of the polyurethane family, either alone or in a mixture with each other, preferably it is a mixture of polyurethanes resulting from the condensation between at least one isocyanate and at least one polyol constituted by polyesters (polyester polyurethanes) and between at least one isocyanate and at least one polyol constituted by poly ethers (poly ether polyurethanes).

[0030] According to a preferred aspect of the present invention, said at least one isocyanate is preferably 4,4'-diphenylmethane diisocyanate (CAS 101-68-8).

[0031] According to another preferred aspect of the present invention, said at least one polyol is selected from poly(tetrahydrofuran) (CAS 25190-06-1), poly(oxy(methyl-l,2-ethanediyl) (CAS 9042-19-7), 1,4-butanediol (CAS 110-63-4) and mixtures thereof.

[0032] According to another preferred aspect of the present invention, said at least one polyol is selected from poly(tetrahydrofuran) (CAS 25190-06-1), poly(oxy(methyl-l,2-ethanediyl) (CAS 9042-19-7), 1,4-butanediol (CAS 110-63-4), polyol polyester having CAS number 27925-07-1 and mixtures thereof.

[0033] In embodiments, said at least one polyol constituted by polyethers is selected from poly(tetrahydrofuran) (CAS 25190-06-1), poly(oxy(methyl-l,2-ethanediyl) (CAS 9042-19-7) and mixtures thereof.

[0034] In embodiments, said at least one polyol constituted by polyesters is preferably the polyol polyester having CAS number CAS 27925-07-1 (Poly(neopentyl glycol adipate).

[0035] According to an aspect of the present invention, said polyols constituted by polyesters and said polyols constituted by polyethers may be mixed with each other in variable ratios to give "starting" mixtures, which may also comprise at least one isocyanate.

[0036] For example, said variable ratios between polyols constituted by polyesters and polyols constituted by poly ethers are of the 1 : 1 or 1 :2 type, respectively.

[0037] For example, said "starting" mixtures may be a "starting" mixture of Ml type, as further set forth below, and a "starting" mixture of M2 type, as also further set forth below. Said Ml and M2 "starting" mixtures, for example may be used in the process according to the invention according to variable M1:M2 ratios between 90: 10 and 70:30, preferably an M1 :M2 ratio of 80:20. In other embodiments, said Ml and M2 "starting" mixtures may be used in the process according to the invention according to variable M1 :M2 ratios between 15:85 and 25:75, for example an M1 :M2 ratio of 20:80. For example, when the Ml "starting" mixture comprises at least one polyol constituted by polyethers and the M2 "starting" mixture comprises at least one polyol constituted by polyesters, said Ml and M2 "starting" mixtures may be used in an M1 :M2 ratio between 15:85 and 25:75, for example, an M1 :M2 ratio of 20:80.

[0038] The process for the production of soles / treads according to the present invention comprises the following steps: a) forming the blend for the preparation of at least one thermosetting polymer selected from the members of the polyurethane family, preferably it is a thermosetting polymer composed of a mixture of:

[0039] - polyester polyurethanes resulting from the condensation of at least one isocyanate with at least one polyol constituted by polyesters, and

[0040] - polyether polyurethanes resulting from the condensation of at least one isocyanate with at least one polyol constituted by polyethers; b) mixing said blend from step (a) with an appropriate catalyst accurately weighed; c) introducing said blend mixed with the catalyst of step (b) into a heated closed mold, and under vacuum conditions, in which the molding process takes place; and optionally, d) incorporating a fabric and / or a plastic or cellulose film bearing the graphics you wish to integrate with the sole / tread.

[0041] According to an aspect of the present invention, the formation of the blend of at least one thermosetting liquid polymer of step (a) is done by directly using the polymers as they are on the market or by blending them together and / or adding specific additives known to the skilled in the art, which improve the technical characteristics of the polymer itself, for example, the dielectric or electrical conductivity characteristics. Non-limiting examples of additives that may be added are the compounds [pentaerythritol tetrakys 3-(3,5-ditert-butyl-4- hydroxyphenyl )propionate] (CAS 6683-19-7) and Tns-(2,4-di-tert-butyl)-phosphite (CAS 31570-04-4).

[0042] According to a preferred aspect of the present invention, said accurately weighted appropriate catalyst of step (b) is selected from the class of the amine catalysts, for example said amine catalyst is, but not limited to, the amine 1,4-diazabicyclooctane (CAS 280-57-9). Said catalyst, appropriately selected according to the knowledge of the technician in the field, is introduced into the mixture of step (a) in an amount between 0.1% and 0.4% by weight, preferably in an amount between 0.1 and 0.3% by weight, to the weight of the mixture. The addition is done by means of an apparatus equipped with a volumetric dosing / mixing device that simultaneously doses the right amount of catalyst and blend it intimately with the polymer from step (a). Blending between polymer, and / or the polymer blend, and catalyst occurs simultaneously with dosing. Dosing of the catalyst and its blending with the polymer, and / or polymer blend, has taken place shortly before the material is introduced into the mold. Dosing of the catalyst, and its mixing with the polymer and / or polymer blend, have to occur no more than 5 minutes before the introduction of the material into the mold, preferably 1 minute before, optimally 10 seconds before the introduction of the material into the mold.

[0043] According to the present invention, the introduction of the blend containing the catalyst obtained from step (b) inside the heated mold occurs in two steps: a first step involves the introduction of the mixture from step (b) by gravity through a hole (pouring channel) present in the upper part of the closed mold; a second step involves the activation of the vacuum inside the mold cavity, thus allowing the blend from step (b) to reach all points of the mold cavity regardless of the desired shape and thickness.

[0044] According to an aspect of the present invention, the viscosity of the blend, which is poured into the mold, is about 2,000 Pa*s (kinematic viscosity measured at 20°C).

[0045] 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 vacuum conditions of about - 0.9 bar for 10 minutes.

[0046] Advantageously, the molding process takes place under vacuum conditions, thus preventing the blend mixed with the catalyst from incorporating air during the process and enabling the production of a sole / tread of compact material. The molds for molding soles / treads in the process of the present invention are, preferably, made of aluminum alloy, are obtained by casting and subsequent machining or directly formed from a solid block of aluminum by machining. Furthermore, said molds are closed, that is, comprised of two parts that, when overlapping, leave an inner cavity free that will be filled with the blend from step (b) and that has the final shape of the sole / tread to be obtained.

[0047] The mold is equipped in the upper part (lid) with one or more holes, which allow the introduction of the blend of step (b), and one or more pieces of equipment that are capable of creating the desired vacuum value inside the cavity at the appropriate time.

[0048] The mold is also equipped with a gasket arrangement, the gaskets being positioned between the two main parts it is composed of (upper part, lid, and lower part), which is intended to hold the blend of step (b) inside the cavity at the time vacuum is applied to the mold.

[0049] The soles produced by the process according to the present invention, thanks to their high performance in terms of abrasion resistance and consequent long durability, light weight, high grip and consistent performance over a wide range of temperatures, may directly constitute the tread of the soles, that is, the part in contact with the ground.

[0050] In particular, the soles / treads produced by the process of the invention are characterized by:

[0051] - hardness between 60 and 70 Shore A, measured at 23°C and stable between +6°C and +50°C (test method GB / T 531.1-2008);

[0052] - very high abrasion resistance with values up to 15 mm3, more typically between 20 mm3and 40 mm3(test method GB / T9867-2008 Method A);

[0053] - density between 0.990 g / cm3and 1.100 g / cm3(test method GB / T1033.1-2008 Method A);

[0054] - coefficient of friction on dry surfaces from 0.99 to 1.35 and coefficient of friction on wet surfaces from 0.45 to 0.75 (test method GB / T 4100-2015 Annex M);

[0055] - very high oil immersion resistance, between 0.1% and 3% (test method UL 50E-2020 Clause 8.13.4 & ASTM D471-160).

[0056] All of the previously listed characteristics, with the exception of hardness which, as stated, keeps a stable value between +6°C and +50°C, are kept stable and / or with minimal variations over a temperature range of -20°C to +40°C, or +6°C to +60°C, or -40°C to +40°C, depending on the different blends. Therefore, said characteristics / performance are kept stable in temperature ranges from as low as 54°C (+6°C to +60°C) to over 80°C (-40°C to +40°C).

[0057] Furthermore, the soles / treads produced according to the present invention may have very different thicknesses, in particular, there is the possibility of obtaining sole / tread thicknesses from 0.6 mm to 10 mm; typically from 0.6 mm to 5 mm.

[0058] An additional, extremely important and advantageous improvement resulting from the process according to the present invention is that the sole / tread obtained by said process, unless intentionally colored or customized with specific graphics, is completely transparent and colorless, as well as odorless, unlike any other sole obtained by other technologies and other materials.

[0059] A sole / tread produced by the process according to the present invention, characterized by the properties listed above, is another object of the present invention. Furthermore, the sole / tread produced by the process according to the present invention comprises a compact material and does not comprise thermoplastic polymers and / or foams. According to a further aspect, the sole / tread produced by the process according to the present invention does not have cushioning characteristics. Preferably, the sole / tread produced by the process according to the present invention is a tread, that is, the portion of the sole (or shoe) in direct contact with the ground.

[0060] A further object of the present invention is the use, in a process for the production of soles according to the present invention, of a thermosetting liquid polymer selected from the members of the polyurethane family, alone or in a mixture with each other, preferably a mixture of polyurethanes resulting from condensation between isocyanate and polyols constituted by polyesters (polyester polyurethanes) or polyols constituted by polyethers (polyether polyurethanes).

[0061] The process of the invention is capable of producing soles / treads of various shapes, sizes and thicknesses. Therefore it is possible to obtain both flat and smooth soles (Figure 1), which cover the entire lower part of the footwear, and smaller portions, which may occupy only some sections of the lower part of the footwear for aesthetic and / or functional reasons, for example, the heel and / or the toe and / or the shoe waist and / or the toe cap. Furthermore, according to another aspect of the present invention, it will also be possible to produce so- called "box" soles / treads (Figure 2) that have a raised edge (Figure 2, sections denoted by the letters (D1) and (D")) thus forming a three-dimensional container in which the midsole may be housed.

[0062] In this case, while maintaining very small sole / tread thicknesses at the lower part and the wall, and typically wall thicknesses between 0.6 mm and 3 mm, it is possible to produce "box" soles with side walls (Figure 2, sections depicted by the letters (D1) and (D")) even very extended in height, for example, with heights from 1 mm to 70 mm.

[0063] According to a preferred aspect of the present invention, in cases where it is necessary for the sole produced according to the process of the invention to be coupled to another element constituting the lower part of the footwear, for example in cases where said sole constitutes only a part of the tread or in cases where it has a "box" structure that has to be filled with foamed polyurethane capable of forming the midsole, said sole will not need to be treated in advance with chemical agents and coated with glue before receiving, in a subsequent stage, the polyurethane that, by foaming, will form the midsole.

[0064] Indeed, the sole produced according to the process of the present invention may be inserted, as such, into the mold in which the second element that constitutes the other lower part of the footwear (for example, a polyurethane foam midsole) is formed, and said second element may be directly formed on top of it, thus creating a perfect adhesion / cohesion between the two parts without the need for further chemical treatments, components and / or adhesives. Alternatively, the lower part of the same mold used for the production of the sole / tread according to the present invention may be used for the formation of said second element by replacing the upper part of the mold with a lid of a suitable shape, also ensuring significant cost savings because it is no longer necessary to produce a second, dedicated set of molds to produce the midsole.

[0065] This aspect constitutes an additional advantage of the sole / tread produced according to the present invention, because it makes it possible to avoid the chemical treatments, the deposition of glues and / or other components that are instead necessary in the case of a shoe with a foamed polyurethane midsole and a vulcanized rubber sole / tread, which must be mandatorily and preventively prepared by a gentle and dedicated process, with an environmental impact which is non-neutral and potentially even high.

[0066] The process according to the present invention has many advantages over what is currently described and found in the known art. The resulting technical soles / treads are indeed characterized by better characteristics and performance; in particular, compared with vulcanized-rubber technical soles, which are the most commonly found and used in the market today, they have:

[0067] - ability to be produced in a wide range of thicknesses, ranging from very small thicknesses (starting from a few tenths of a millimeter, for example, 0.6 mm minimum thickness) to thicknesses up to 8-10 mm;

[0068] - low density, 7-9% lower than the vulcanized rubber;

[0069] - the combination of low density, very high abrasion resistance and the possibility of very thin thicknesses allows producing soles that are aesthetically identical to the rubber soles but with weigh that is 60% to 80% lower;

[0070] - high durability, up to three times that of the vulcanized rubber sole using the more durable blend (the abrasion resistance of the soles produced by the process according to the present invention is typically 20 mm3[measured according to GB / T9867-2008 Test Method A], significantly lower than what is obtained in the case of the vulcanized rubber soles produced by compression, which give values starting at 60 mm3, and above);

[0071] - extremely high grip, equal to or better than the best rubber blends on the market on both wet surfaces and dry surfaces (coefficient of friction on dry surfaces from 0.99 to 1.35 and coefficient of friction on wet surfaces from 0.45 to 0.75 [GB / T 4100-2015 test method Annex M]);

[0072] - consistent performance over a wide temperature range, as previously stated, evaluated by carrying out all characterization tests at various temperatures and recording the time when measured values varied from those recorded under room / standard temperature conditions;

[0073] - possibility of aesthetic customization that is easy, infinite, limitless in shapes and colors, and quickly changeable due to the natural transparency of the sole / tread produced according to the process of the present invention, which allows one to see through it as if it were "glass", and the possibility of integrating colored graphics into its mass. Said colored graphics could be easily embedded in the sole / tread by using, for example, a fabric or plastic or cellulose film bearing the graphics to be integrated (optional step (d) of the process according to the present invention).

[0074] Peculiarities and advantages of the process according to the present invention will be set forth, for illustrative and non-limiting purpose, by the experimental section below.

[0075] Experimental section

[0076] Example 1 - Production of a flat sole / tread according to the present invention (Figure 1)

[0077] A mixture was prepared consisting of the components of Ml and M2, as set forth in Table 1 and Table 2, in a 80:20 proportion, respectively (step (a)).

[0078] Table 1 : Qualitative / quantitative composition of Ml

[0079] Table 2: Qualitative / quantitative composition of M2

[0080] In parallel, a closed mold is prepared, connected to the vacuum connections and heated to 80°C.

[0081] The mixture of the two polyurethanes prepared in step (a) is quickly fed, immediately after mixing, into an apparatus for dosing and blending the catalyst 1,4-diazabicyclooctane (CAS 280-57-9) in the proportion of 0.4% by weight to the weight of the polyurethane mixture (step (b))-

[0082] The mixture to which the catalyst from step (b) has been added is immediately poured into the casting channel / sprue of the preheated mold, taking care to pour 50% more than the volume of the final sole / tread to ensure the complete filling of the mold (step (c)).

[0083] When the pouring step is finished, wait a few seconds, preferably in the tens, for example 30 seconds, and then apply the vacuum to the mold with a pressure of -0.9 bar. The polymerization reaction is allowed to proceed for a time between 500 and 750 seconds, depending on the size of the sole / tread; typically about 600 seconds for size 42 soles.

[0084] Once the time required for the complete polymerization has elapsed, the vacuum is removed and the mold is opened, manually extracting the now-solid sole, which will be sent for classic finishing operations (deflashing, polishing, packaging).

[0085] Example 2 - Production of a sole, which comprises a midsole, accordins to the present invention

[0086] For the production of a sole, which comprises a midsole, all the steps previously described in Example 1 are followed until the mold is opened, which, however, in this case, is not followed by the extraction of the solid sole / tread.

[0087] As a matter of fact, once the mold is opened, the "box" sole / tread (20) is left in the lower part of the mold itself and the mold heating system is eliminated.

[0088] Meanwhile, polyurethane (PU) blending is carried out with the appropriate catalyst. Next, the catalyzed PU is poured into the "box" sole that will contain it, thus constituting the lower part of the “mold”.

[0089] The mold is then closed at the top with a lid that has a cavity of a suitable shape for the polyurethane to expand and form a midsole that will contact, at its top, with the lower part of the upper.

[0090] The mold is left closed long enough to complete expansion and cross-linking of the foamed polyurethane, which depends on the type and quantity of the latter, after which the mold is opened and the sole complete with midsole is pulled out manually.

[0091] The resulting composite sole is sent to the classical finishing operations (deflashing, polishing, packaging).

[0092] Example 3 - Production of a sole / tread accordins to the present invention

[0093] A mixture was prepared consisting of the components of Ml and M2, as set forth in the previous Tables 1 and 2, in a 75:25 proportion, respectively (step (a)).

[0094] Anti-static and conductive additives are added to enable the final product to have an electrical resistance between 100 kOhm and 35 MOhm.

[0095] Proceed as in Examples 1 or 2 described above to obtain a flat sole / tread (10) or "box" sole / tread (20), according to the present invention.

[0096] Example 4 - Production of a flat sole / tread according to the present invention

[0097] A mixture was prepared consisting of the components of Ml and M2, as set forth in Table 3 and Table 4, in a 20:80 proportion, respectively (step (a)).

[0098] Other Ml :M2 proportions that may be used are, for example, 15:85 and 25:75.

[0099] Table 3: Qualitative / quantitative composition of Ml

[0100] Table 4: Qualitative / quantitative composition of M2

[0101] Once the components Ml and M2 are mixed, proceed as for Examples 1 or 2 described above to obtain a flat sole / tread (10) or "box" sole / tread (20), according to the present invention.

Claims

CLAIMS1. A process for the production of soles / treads for footwear, characterized by the following steps: a) forming the blend for the preparation of at least one thermosetting polymer selected from the members of the polyurethane family, preferably it is a thermosetting polymer composed of a mixture of:- polyester polyurethanes resulting from the condensation of at least one isocyanate with at least one polyol constituted by polyesters, and- polyether polyurethanes resulting from the condensation of at least one isocyanate with at least one polyol constituted by polyethers; b) mixing said blend from step (a) with an appropriate catalyst accurately weighed; c) introducing said blend mixed with the catalyst of step (b) into a heated closed mold, and under vacuum conditions, in which the molding process takes place; and optionally, d) incorporating a fabric or a plastic or cellulose film bearing the graphics you wish to integrate with the sole / tread.

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

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

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

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

6. The process according to any one of the preceding claims, characterized in that said at least one polyol of step (a) is selected from poly(tetrahydrofuran) (CAS 25190-06-1), poly(oxy(methyl-l,2-ethanediyl) (CAS 9042-19-7), 1,4-butanediol (CAS 110-63-4), polyol polyester having CAS number 27925-07-1, and mixturesthereof.

7. A sole / tread for footwear, produced according to the process of claim 1, characterized by:- hardness between 60 and 70 Shore A, measured at 23°C (test method GB / T 531.1- 2008);- abrasion resistance up to 15 mm3, preferably between 20 mm3and 40 mm3(test method GB / T9867-2008 Method A);- density between 0.990 g / cm3and 1.100 g / cm3(test method GB / T 1033.1-2008 Method A);- coefficient of friction on dry surfaces from 0.99 to 1.35 and coefficient of friction on wet surfaces from 0.45 to 0.75 (test method GB / T 4100-2015 Annex M);- oil immersion resistance between 0.1% and 3% (test method UL 50E-2020 Clause 8.13.4 & ASTM D471-160).

8. A flat sole / tread for footwear (10), produced according to the process of claim 1, characterized by having a thickness from 0.6 mm to 5 mm.

9. A "box" sole / tread for footwear (20), produced according to the process of claim 1, characterized by having a thickness from 0.6 mm to 5 mm in the lower portion and an edge ((D1) and (D")) from 0.6 mm to 3 mm thick which rises laterally by a height from 1 mm to 70 mm.

10. Use of a mixture of:- polyester polyurethanes resulting from the condensation of at least one isocyanate with at least one polyol constituted by polyesters, and- polyether polyurethanes resulting from the condensation of at least one isocyanate with at least one polyol constituted by polyethers for the production of technical soles for footwear according to the process of claim 1.

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