METHOD FOR PRODUCING MORE SUSTAINABLE COMPOSITE MATERIALS FOR USE IN THE MANUFACTURE OF VEHICLE TIRES

Description

[0001] The invention relates to a method for producing a composite material for use in the manufacture of vehicle tires, an associated method for producing a vehicle tire, a reinforcing cord for use in such methods, as well as composite materials and vehicle tires that can be produced by the method and that comprise such reinforcing cords. The use of such a reinforcing cord or composite material in the manufacture of vehicle tires is also disclosed.

[0002] The subject matter of the invention is defined in the attached claims.

[0003] With a growing awareness of the need for more sustainable resource management, there is also a steadily increasing demand in the tire manufacturing sector to make the production process more sustainable and environmentally friendly. Furthermore, given the long-term uncertainty surrounding the availability of fossil fuels, there is a growing need to develop new sources of raw materials to ensure a secure supply of the materials required for tire production in the long term.

[0004] WO 2012 / 174451 A1 discloses a utilization of waste streams from industrial cycloalkane oxidation processes. The aim is to increase the monomer content in the waste stream or to provide α,ω-difunctional alkanes.

[0005] DE 102018209522 A1 relates to a reinforcing cord containing at least one yarn, wherein at least one yarn contains filaments made of PA PACM 12, which is produced from the starting materials 1,12-dodecanedioic acid and bis(4-aminocyclohexyl)methane, and wherein at least the 1,12-dodecanedioic acid is produced from renewable raw materials.

[0006] WO 2014 / 040804 A1 relates to a reinforcing cord for elastomeric products, in particular for a vehicle pneumatic tire, consisting of at least one yarn, wherein the at least one yarn consists of polyethylene furanate (PEF), the PEF being produced wholly or at least partly from biomass and / or renewable raw materials.

[0007] EP 1 757 636 A1 relates to a polyamide resin and in particular a polyamide resin comprising an adipic acid unit, a pentamethylenediamine unit and a hexamethylenediamine unit as constituent parts thereof and which can be produced using raw materials which are free from the formation of carbon dioxide.

[0008] The present invention relates to the field of so-called reinforcing cords and the composite materials produced therefrom. These reinforcing cords are used as structural elements in the manufacture of modern vehicle tires, particularly pneumatic tires. For this purpose, corresponding reinforcing cords are usually embedded in a vulcanizable rubber compound to obtain a vulcanizable composite material.

[0009] The various components of a modern pneumatic tire are typically made from different composite materials. These materials can differ, for example, in the vulcanizable rubber compound used and / or the type, number, and positioning of the reinforcing cords. The specific construction is adapted to the requirements of the respective tire components and layers. Typical applications for such vulcanizable composite materials include the carcass layers, bead reinforcements, belt bands, and the belt itself. After vulcanizing these composite materials, or the blanks containing them, vulcanized composite materials are obtained in which the reinforcing cords are embedded in the vulcanized rubber compound.

[0010] Reinforcing cords are generally familiar to experts and typically consist of one or more twisted yarns. So-called hybrid cords, such as duplex or triplex cords, are also known, in which several yarns, for example made of different materials, are twisted together at the ends.

[0011] The materials used in reinforcing cords are usually selected according to their physicochemical properties and in light of the specific requirements. Among the materials regularly used in reinforcing cords, polyamides, i.e., the condensation products of a polycarboxylic acid (e.g., a dicarboxylic acid) and a polyamine (e.g., a diamine), are of particular importance. Polyamides, especially aliphatic polyamides, are an essential component of numerous reinforcing cords for many applications due to their advantageous physicochemical properties. The reinforcing cords used in the prior art regularly comprise polyamide yarns that are petrochemically produced, i.e., petroleum-based materials.

[0012] To increase the sustainability of manufacturing such composite materials and reduce dependence on fossil raw materials, prior art attempts have been made to replace petrochemical-based yarns with natural fibers. However, this is regularly considered disadvantageous with regard to the quality and reproducibility of the resulting composite materials, particularly because natural fibers often lack the necessary physicochemical properties, such as shrinkage behavior. Furthermore, some natural fibers exhibit other properties that make them less suitable for use in composite materials for vehicle tires, such as the well-known moisture sensitivity of rayon. In addition, natural fibers are typically only available as staple fibers and not as continuous filaments.

[0013] The primary objective of the present invention was to eliminate or at least reduce the disadvantages of the prior art described above.

[0014] In this respect, the object of the present invention was to provide a method for producing a composite material which can be operated in a more sustainable manner and which reduces dependence on fossil raw materials.

[0015] The task was to obtain composite materials for the production of vehicle pneumatic tires using the specified method, materials that, despite high sustainability, possess excellent properties and with which high-performance vehicle pneumatic tires can be manufactured.

[0016] Furthermore, it was an object of the present invention that composite materials should be producible in a reproducible manner using the specified method, so that the high quality of the produced composite materials can be continuously ensured.

[0017] It was desirable that the specified method for producing composite materials be as flexible as possible with regard to the starting materials used, in order to ensure the greatest possible security of supply with regard to raw materials. Furthermore, it was an object of the present invention that the specified method for producing a composite material should allow for flexible and specific adjustment of the physicochemical properties of the composite material and the vulcanizates obtained from it, thereby enabling the corresponding composite materials to be precisely adapted to the requirements of various applications while maintaining a high degree of sustainability.

[0018] One requirement was that the specified process for manufacturing a composite material should ideally be usable on a large-scale industrial scale, enabling time- and cost-efficient vehicle tire production.

[0019] In this context, a further object of the present invention was to specify a method for manufacturing vehicle tires which is based on the specified method for manufacturing composite materials and thereby enables a particularly resource-efficient production of vehicle tires which should have a consistently high quality.

[0020] In this respect, a further object of the present invention was to provide a reinforcing cord that can be used in the inventive process for the production of composite materials. It was desirable that the reinforcing cord to be provided should be more resource-efficient to produce, but should not be, or only insignificantly, inferior with regard to its physicochemical properties to those of comparable petrochemically produced reinforcing cords.

[0021] Based on the above tasks, an additional task was to specify a composite material that can be produced using the specified method and also includes the specified reinforcement chord.

[0022] It was also an object of the present invention to provide a vehicle tire which comprises a corresponding composite material or corresponding reinforcing cords and can therefore be produced in a particularly sustainable manner.

[0023] The inventors of the present invention have now discovered that the aforementioned problems can surprisingly be solved by using a bio-based polyamide yarn in the production of composite materials for use in the manufacture of vehicle tires. This yarn comprises one of two specific bio-based polyamides from the large number of possible polyamides, which are produced from selected starting monomers, provided that these starting monomers are at least partially derived from biomass. This makes it possible to significantly reduce dependence on fossil raw materials, particularly petroleum, and to produce a particularly important component for the manufacture of vehicle tires using a sustainable process, resulting in especially environmentally friendly products.

[0024] Due to the high demands placed on the physicochemical properties of materials used in reinforcing cords, this finding is surprising, as it was not anticipated that composite materials produced using appropriate processes could actually be suitable for use in modern vehicle tires and, moreover, possess excellent properties comparable to those of composite materials made from petrochemical reinforcing cords. This is partly because the production of starting monomers derived from biomass is regularly associated with significant chemical and process engineering challenges, with particularly high demands placed on the processing of the materials and the necessary purity levels, which are usually difficult to achieve when starting from biomass.Accordingly, starting compositions for the polymerization of polymers whose starting monomers are produced from biomass sometimes contain impurities and / or by-products from the preceding conversion of the biomass, which are not present in comparable monomers from petrochemical processes and which can adversely affect the physicochemical properties of the polymers that can be produced from them, which is regularly considered problematic for safety-sensitive products such as vehicle tires.

[0025] According to the inventors of the present invention, with regard to the use of polyamides, it is possible, despite these reservations of the person skilled in the art, to reliably and reproducibly obtain reinforcing cords with excellent properties for two specific types or combinations of starting monomers. These cords can be used in composite materials to manufacture reproducibly high-performance vehicle tires. The inventors have concluded that the deviations in the physicochemical behavior of the polyamides produced from the bio-based starting monomers are surprisingly negligible in these cases, and / or that the differences are particularly evident in areas that are of little relevance to the application of the composite materials according to the invention in vehicle tires.

[0026] The aforementioned problems are solved accordingly by the subject matter of the invention as defined in the claims. Preferred embodiments of the invention are described in the dependent claims and the following descriptions.

[0027] Such embodiments, which are hereinafter referred to as preferred, are combined in particularly preferred embodiments with features of other embodiments referred to as preferred. Combinations of two or more of the embodiments referred to below as particularly preferred are therefore especially preferred. Also preferred are embodiments in which a feature of one embodiment referred to as preferred to any degree is combined with one or more further features of other embodiments referred to as preferred to any degree. Features of preferred reinforcing cords, composite materials, vehicle tires, and uses are derived from the features of preferred methods.

[0028] The invention relates to a method for producing a composite material for use in the manufacture of vehicle tires, comprising the following process steps: a) Producing or providing a starting composition comprising as starting monomers: i) ε-Aminocaproic acid and / or ε-Caprolactam, and / or ii) Hexamethylenediamine and Hexamethylenedicarboxylic acid, wherein the starting monomers contained in the starting composition are at least partially produced from biomass, based on the amount of substance of the starting monomers contained in the starting composition, b) Polymerizing the starting monomers contained in the starting composition to form a bio-based polyamide, forming the bio-based polyamide to form a bio-based polyamide yarn, and processing the bio-based polyamide yarn to form a reinforcing cord, and c) Embedding the reinforcing cord in a vulcanizable rubber compound to obtain the composite material.

[0029] The process according to the invention produces composite materials, in particular unvulcanized composite materials, which can subsequently be used in the manufacture of vehicle tires, e.g., as belt bands. For this purpose, a starting composition is provided that comprises specific starting monomers. These starting monomers can be ε-aminocaproic acid and / or ε-caprolactam, as well as, additionally or alternatively, the combination of the two monomers hexamethylenediamine and hexamethylenedicarboxylic acid.

[0030] In accordance with the expert understanding, different polyamides are obtained by reacting a starting composition comprising the starting monomers according to i) and / or ii), and it is also possible, in principle, to produce copolymers using both groups i) and ii). In accordance with the expert understanding, the starting composition comprises the starting monomers of the respective types in a certain quantity, such that each starting monomer is present in the starting composition in a specific amount.

[0031] A key aspect of the invention is that the starting monomers contained in the initial composition are at least partially produced from biomass. This refers to the amount of substance of the starting monomers contained in the initial composition, meaning that at least a portion of the amount of starting monomers is produced from biomass.

[0032] In accordance with the skilled person's understanding, a single molecule of a starting monomer is considered to be produced from biomass if biomass was used as the starting material in its production. Although it is explicitly preferred that a molecule of the starting monomers produced from biomass be produced entirely from biomass, i.e., without the use of chemicals not derived from biomass, it is understood by the skilled person that this is not a requirement for a starting monomer to be considered as being produced from biomass. For example, a basic chemical produced from biomass, such as 5-(hydroxymethyl)furfural, can be reacted with other substances to produce the aforementioned starting monomers. These other substances need not necessarily be produced from biomass themselves to still be considered a molecule produced from biomass.

[0033] In summary, for the purposes of the present invention, a single molecule of a starting monomer is thus produced from biomass if it is obtained directly or indirectly from biomass or its conversion, wherein the starting composition to be used according to the invention comprises specific starting monomers, of which, in relation to the amount of substance of the starting monomers in the starting composition, at least a part of the molecules must be produced from biomass in this form.

[0034] The starting composition can contain other monomers besides the starting monomers, for example for the production of copolymers, and can also include, for example, common additives or polymerization systems.

[0035] In the case of group ii), the starting composition may also already contain the reaction product hexamethylenediamine adipate (so-called "AH salt"), which is a reaction product of hexamethylenediamine and hexamethylenedicarboxylic acid, with corresponding intermediates being taken into account proportionally when determining the content of starting monomers in the starting composition. In accordance with the skilled person's understanding, it is therefore also possible, and even preferred for some applications, to first prepare intermediates from the starting composition and the starting monomers, e.g., hexamethylenediamine adipate, which are then polymerized, so that, within the scope of the present invention, the polymerization of intermediates also constitutes a polymerization of the starting monomers contained in the intermediates.

[0036] In step b) of the process according to the invention, the starting monomers contained in the initial composition are polymerized, i.e., a polymer is produced from the starting monomers. Due to the fact that the starting monomers are at least partially produced from biomass, a bio-based polyamide is obtained. This bio-based polyamide is then processed into a bio-based polyamide yarn, which can be carried out efficiently by a melt spinning process. A process according to the invention is preferred in that the bio-based polyamide yarn is formed using an extruder. Another preferred process according to the invention is one in which the bio-based polyamide yarn is produced by a spinning process, preferably a melt spinning process.

[0037] From this bio-based polyamide yarn, which comprises the bio-based polyamide produced from the starting monomers that are at least partially made from biomass, a reinforcing cord is manufactured, for example by twisting two or more such bio-based polyamide yarns together.

[0038] The resulting reinforcing cord is embedded in a vulcanizable rubber compound to obtain a vulcanizable composite material which can then be used in the manufacture of vehicle tires.

[0039] As explained above, the starting composition to be used and the starting monomers contained therein can be produced or provided. The production of the specified starting monomers from biomass is generally known in the prior art, as is the obtaining of polyamides by polymerization of the corresponding starting monomers. In this respect, the person skilled in the art can refer to processes known from the prior art, such as those disclosed, for example, in US 9783473 B2, US 9982094 B2, US 9988491 B2, US 10081612 B2, CN 104277021, US 4400468, US 8927768 B2, or US 9199961 B2 and the documents cited therein. To produce the starting monomers to be used according to the invention or to polymerize them, the person skilled in the art thus refers to the appropriate process, depending on the starting monomer to be produced and the biomass used.

[0040] For the vast majority of companies in the tire manufacturing sector, which do not regularly have large-scale facilities for the production of starting monomers, it will be practical to purchase the corresponding starting monomers, which are at least partially produced from biomass, from specialized suppliers and to provide them using the inventive method.

[0041] If the specialist in the field of tire manufacturing does not have his own access to facilities for the polymerization of the relevant starting materials, the polymerization can be carried out, for example, at a contract manufacturer specializing in the production of polymers, for whom the conversion of corresponding starting monomers to polyamides will regularly pose no problems in light of the state of the art.

[0042] The bio-based polyamide and the bio-based polyamide yarn obtained therefrom are processed into a reinforcing cord in the process according to the invention, whereby in principle the processes and methods can be used that can also be used in the processing of petrochemically produced polyamide yarns, which can be seen as a great advantage of the process according to the invention with regard to the easy implementation of the process in manufacturing.

[0043] Determining whether a composite material was produced using the inventive method and has appropriately designed reinforcing cords is advantageously possible by applying ASTM D 6866 from 2021, which concerns the so-called C-14 method and is entitled "standard test method for determining the biobased content of solid, liquid and gaseous samples using radiocarbon analysis". Such starting monomers, which are produced from biomass, as well as the bio-based polyamides obtained from them and the polyamide yarn produced therefrom, have a significantly higher proportion of <14C in the carbon than petrochemically produced materials, i.e., materials produced from petroleum.

[0044] Although the process according to the invention makes it possible to use two different groups of starting monomers and also allows for the formation of copolymers, the inventors consider it preferable to use only one of the aforementioned groups i) or ii) of starting monomers, whereby particularly suitable specific starting monomers could be identified for hexamethylenediamine and hexamethylenedicarboxylic acid, respectively. A preferred method according to the invention is therefore one in which the starting composition comprises the starting monomers ε-aminocaproic acid and / or ε-caprolactam, preferably ε-caprolactam, and wherein the starting composition preferably consists substantially of these starting monomers.A preferred method according to the invention is one in which the starting composition comprises the starting monomers hexamethylenediamine and hexamethylenedicarboxylic acid, wherein the starting composition preferably consists substantially of these starting monomers. A preferred method according to the invention is also one in which the hexamethylenediamine is 1,6-diaminohexane and / or the hexamethylenedicarboxylic acid is 1,6-hexanedioic acid.

[0045] Although the process according to the invention is not fundamentally limited in terms of how the starting monomers are to be produced from the biomass, the inventors consider it particularly advantageous if the synthesis route proceeds via 5-(hydroxymethyl)furfural (5-HMF), which can advantageously be produced particularly efficiently and on a large scale from biomass, especially from cereal crops, e.g., from high-fructose corn syrup. All of the aforementioned starting monomers can advantageously be produced by reacting 5-HMF, so that the process according to the invention can be operated particularly efficiently when using 5-(hydroxymethyl)furfural, since the production of the starting materials is simplified by a partially overlapping synthesis route.A preferred method according to the invention is therefore one in which the starting monomers are at least partially produced by reacting 5-(hydroxymethyl)furfural, wherein the 5-(hydroxymethyl)furfural was produced from biomass.

[0046] It can be seen as an advantage of the process according to the invention that it is very flexible with regard to the biomass used for the production of the starting monomers, and in the inventors' opinion, there are no limitations in this respect. This ensures a particularly high level of supply security. A preferred method according to the invention is one in which the biomass is selected from the group consisting of plant and animal biomass, preferably from the group consisting of plant biomass, and most preferably from the group consisting of cereal plants.

[0047] Even though a more sustainable production of composite materials is possible with a small proportion of bio-based monomers in the initial composition, maximizing environmental compatibility and optimizing resource utilization makes it sensible to produce the largest possible proportion of the starting monomers from biomass. In accordance with expert understanding, this again refers not to the production of the individual molecules, but to the quantity of substance and thus to the bio-based proportion of the starting monomers in the initial composition.A preferred method according to the invention is one in which the starting monomers contained in the initial composition are produced from biomass to a degree of 40% or more, preferably 70% or more, particularly preferably 90% or more, very preferably 95% or more, further preferably 99% or more, and particularly preferably substantially completely, based on the amount of substance of the starting monomers contained in the initial composition. It is preferred if the aforementioned proportions are adjusted for each of the starting monomers used.

[0048] According to the inventors, an advantage of the process according to the invention is that, in addition to bio-based starting monomers, monomers conventionally produced from petroleum can also be used, as the process according to the invention is flexible in this respect. While it is advantageous to keep the proportion of these monomers as low as possible with a view to the most sustainable possible production of the composite materials, the inventors of the present invention have identified that the possibility of including petrochemically produced starting monomers offers a significant opportunity with regard to the performance of the resulting reinforcing cords.In particular, if the available bio-based starting monomers result in reinforcing cords during the production of the composite materials that do not yet adequately meet the specific requirements of the intended application, for example with regard to the modulus of elasticity, the targeted addition of petrochemically produced starting monomers can compensate for such deficiencies. In light of the foregoing, a person skilled in the art can determine, through standard test series, what proportion of petroleum-based starting monomers represents the ideal compromise between the physicochemical properties of the reinforcing cords and maximum sustainability. A preferred method according to the invention is one in which the starting monomers contained in the initial composition are at least partially produced from petroleum, based on the amount of starting monomers contained in the initial composition.A preferred method according to the invention is one in which the starting monomers contained in the starting composition are produced from petroleum to a degree of 0.1 to 60%, preferably 0.2 to 30%, particularly preferably 0.5 to 10%, and most preferably 1 to 5%, based on the amount of substance of the starting monomers contained in the starting composition.

[0049] Analogous to the foregoing, the process according to the invention also advantageously allows the use of recycled polyamide, i.e., polyamide that has previously been processed into products and is intended for reuse in the recycling loop. The starting monomers to be used in the process according to the invention are obtained by depolymerizing the recycled polyamide and can thus be used in step a), whereby suitable depolymerization methods are known to those skilled in the art. When carrying out the process according to the invention, it is possible for those skilled in the art to produce the corresponding starting monomers, which are produced by depolymerizing recycled polyamides, for example, themselves or to purchase such material from a supplier.A preferred method according to the invention is therefore one in which the starting monomers contained in the initial composition are at least partially produced by depolymerization of recycled polyamide, based on the amount of starting monomers contained in the initial composition. A preferred method according to the invention is one in which the starting monomers contained in the initial composition are produced by depolymerization of recycled polyamide to a degree of 0.1 to 60%, preferably 0.2 to 30%, particularly preferably 0.5 to 10%, and most preferably 1 to 5%, based on the amount of starting monomers contained in the initial composition.

[0050] In accordance with the skilled person's understanding, the starting monomers described above, which were produced by depolymerization of recycled polyamide, are not considered petroleum-based starting monomers even if the recycled polyamide used for their production was previously produced from petroleum. Thus, when using the preferred processes according to the invention, the skilled person distinguishes between the different starting monomers depending on their source, particularly when both petrochemically produced and recycled starting monomers are to be used.This is beneficial because, although the sustainability of the materials can be advantageously increased by using starting monomers produced by depolymerization of recycled polyamide, the corresponding starting monomers are in many cases less pure than materials produced fresh from petroleum and should therefore be treated as different starting materials.

[0051] It may be considered particularly surprising that the combination disclosed above can, in many cases, be regarded as more advantageous than a process based solely on bio-based starting monomers. Without wishing to be bound by this theory, it seems possible that while the bio-based starting monomers and those produced by depolymerization of recycled polyamide each have certain shortcomings compared to petrochemically produced starting monomers, for example, regarding potential impurities, these shortcomings advantageously balance each other out between the bio-based and those produced by depolymerization of recycled polyamide, resulting in a particularly high degree of sustainability without any shortcomings becoming too pronounced.In principle, the use of starting monomers produced by depolymerizing recycled polyamide can be considered particularly advantageous because it further increases the security of supply of the necessary resources. In particular, this use can also reduce the need for biomass, which can be seen as especially beneficial in view of potential conflicts with food supply.

[0052] The inventors of the present invention have now recognized that particularly advantageous composite materials with particularly advantageous reinforcing cords can be achieved not only when the bio-based starting monomers are combined with petrochemically produced starting monomers or those produced from the depolymerization of recycled polyamide, but that in particularly advantageous embodiments all of these monomers can also be used, resulting in particularly high-performance composite materials whose properties can be adjusted with particular precision.A preferred method according to the invention is therefore one in which the starting monomers contained in the starting composition are produced by depolymerization of recycled polyamide to a proportion of 40% or more, preferably 70% or more, particularly preferably 90% or more, and most preferably 95% or more, from biomass, to a proportion of 0.1 to 59.9%, preferably 0.2 to 29.8%, particularly preferably 0.5 to 9.5%, and most preferably 1 to 4%, from petroleum, and to a proportion of 0.1 to 49.9%, preferably 0.2 to 29.8%, particularly preferably 0.5 to 9.5%, and most preferably 1 to 4%, based on the amount of starting monomers contained in the starting composition.

[0053] Even though the incorporation of non-bio-based starting monomers into the materials used in the process according to the invention is particularly preferred at the level of the starting materials in the opinion of the inventors, especially with regard to the physicochemical properties of the reinforcing cords to be obtained therefrom, the inventors of the present invention have recognized that the bio-based polyamide yarn produced can also be combined with other polyamides, which are not bio-based, during processing in process step b).While it is particularly preferable from a sustainability perspective to produce the bio-based polyamide yarn essentially entirely from bio-based polyamide, analogous to the above statements regarding the starting monomers, it is advantageous, especially for specific high-performance applications, to mix the polyamide yarn with other polyamides in order to be able to adjust the physicochemical properties in a very targeted manner.

[0054] A preferred method according to the invention is one in which the bio-based polyamide yarn comprises the bio-based polyamide in a mass fraction of 40% or more, preferably 70% or more, particularly preferably 90% or more, most preferably 95% or more, and further preferably 99% or more, based on the mass of the bio-based polyamide yarn, wherein the bio-based polyamide yarn particularly preferably consists of the bio-based polyamide. However, a preferred method according to the invention is one in which one or more further polyamides are added to the bio-based polyamide before and / or during the forming of the bio-based polyamide yarn.

[0055] For the production of particularly high-performance composite materials, which have particularly high-performance reinforcing cords, the inventors of the present invention propose to additionally provide petroleum-based polyamide in the bio-based polyamide yarn, i.e., a polyamide that is produced entirely petrochemically. A preferred method according to the invention is therefore one in which the bio-based polyamide yarn additionally comprises petroleum-based polyamide produced from petroleum. A preferred method in this respect is one in which the bio-based polyamide yarn comprises petroleum-based polyamide in a mass fraction in the range of 0.1 to 60%, preferably in the range of 0.2 to 30%, particularly preferably in the range of 0.5 to 10%, and most preferably in the range of 1 to 5%, based on the mass of the polyamide yarn.

[0056] As explained above, it is possible to use recycled polyamide in the process according to the invention by depolymerization, utilizing the starting monomers produced in the process. While this is generally preferred with regard to the quality of the composite materials produced, it also requires a comparatively complex process, which often makes the production of the corresponding starting monomers less cost-effective. A more cost-effective solution, which nevertheless reduces security of supply and dependence on petroleum-based raw materials as well as biomass, is to add recycled polyamide to the bio-based polyamide yarn during processing in process step b), thereby advantageously eliminating the depolymerization step.A preferred method according to the invention is therefore one in which the bio-based polyamide yarn additionally comprises recycled polyamide, which is produced by recycling polyamide-containing products. A preferred method in this respect is one in which the bio-based polyamide yarn comprises recycled polyamide in a mass fraction in the range of 0.1 to 60%, preferably in the range of 0.2 to 30%, particularly preferably in the range of 0.5 to 10%, and most preferably in the range of 1 to 5%, based on the mass of the bio-based polyamide yarn.

[0057] According to the inventors, it is particularly advantageous if the bio-based polyamide is combined with both recycled polyamide and petrochemical-produced polyamide in the production of the polyamide yarn.A preferred method according to the invention is therefore one in which the bio-based polyamide yarn comprises the bio-based polyamide in a mass fraction of 40% or more, preferably 70% or more, particularly preferably 90% or more, and most preferably 95% or more; the petroleum-based polyamide in a mass fraction in the range of 0.1 to 60%, preferably in the range of 0.2 to 30%, particularly preferably in the range of 0.5 to 10%, and most preferably in the range of 1 to 5%; and the recycled polyamide in a mass fraction in the range of 0.1 to 60%, preferably in the range of 0.2 to 30%, particularly preferably in the range of 0.5 to 10%, and most preferably in the range of 1 to 5%, each based on the mass of the bio-based polyamide yarn.

[0058] A method according to the invention is generally preferred, wherein the bio-based polyamide and / or the petroleum-based polyamide and / or the recycled polyamide, preferably comprising all polyamides, PA6 or PA6.6, preferably PA6.6, and particularly preferably consisting of PA6 or PA6.6, in particular PA6.6.

[0059] The inventors of the present invention have identified design parameters that result in particularly advantageous properties for the bio-based polyamide yarns formed according to the invention. These properties, when further processed into reinforcing cords and subsequently embedded in a vulcanizable rubber compound, lead to particularly high-performance composite materials. A preferred method according to the invention is one in which the polyamide yarn has a fineness in the range of 200 to 5000 dtex, preferably in the range of 300 to 2000 dtex or in the range of 1700 to 4500 dtex, and particularly preferably in the range of 400 to 1900 dtex or in the range of 1800 to 2500 dtex. The different ranges are particularly suitable for various applications, with lower values ​​generally used in belt bandages and higher values ​​in carcasses.A preferred method according to the invention is also one in which the polyamide yarn is twisted at 100 to 600 T / m, preferably at 150 to 550 T / m, particularly preferably at 200 to 500 T / m.

[0060] A preferred method according to the invention is one in which the polyamide yarn has a twist factor in the range of 100 to 300, preferably in the range of 150 to 250. The twist factor α is a quantity known to those skilled in the art and is calculated from the twist level in T / m (turns per meter) and the fineness in tex: α = T / m tex 1000

[0061] A method according to the invention is particularly preferred for the production of composite materials for use as belt bandages, wherein the polyamide yarn has a fineness in the range of 300 to 2000 dtex and a twist factor in the range of 100 to 200. A method according to the invention is particularly preferred for the production of composite materials for use in carcass layers, wherein the polyamide yarn has a fineness in the range of 1400 to 5000 dtex and a twist factor in the range of 150 to 250.

[0062] Similarly, the inventors of the present invention have identified specific structures of reinforcing cords that are particularly advantageous when using bio-based polyamide yarns. A preferred method according to the invention is one in which the reinforcing cord comprises two or more yarns, wherein the yarns in the reinforcing cord are preferably twisted together at the ends with 100 to 600 threads / m, more preferably with 150 to 550 threads / m, and most preferably with 200 to 500 threads / m. A preferred method according to the invention is one in which all yarns in the reinforcing cord have a fineness in the range of 200 to 5000 dtex, preferably in the range of 300 to 2000 dtex or in the range of 1700 to 4500 dtex, and particularly preferably in the range of 400 to 1900 dtex or in the range of 1800 to 2500 dtex.A preferred method according to the invention is also one in which the reinforcing cord has a total fineness in the range of 400 to 10000 dtex, preferably in the range of 600 to 7500 dtex, particularly preferably in the range of 800 to 5000 dtex.

[0063] In particular, for the production of composite materials for use as belt bandages or carcass layers, methods according to the invention are preferred in which all yarns are designed as explained above.

[0064] To achieve the greatest possible sustainability benefits of the process according to the invention and the composite materials produced therewith, the inventors of the present invention propose that the reinforcing cords be formed as extensively as possible from the bio-based polyamide. A preferred method according to the invention therefore includes 30% or more, preferably 50% or more, particularly preferably 70% or more, most preferably 90% or more, and most preferably essentially all, of the yarns contained in the reinforcing cord being bio-based polyamide yarns.

[0065] However, according to the inventors, combining the bio-based polyamide yarns with other yarns represents a particularly relevant embodiment, allowing the reinforcing cords to be adapted especially efficiently to the specific requirements of the respective applications. This makes it possible to obtain reinforcing cords whose overall properties can be adjusted with exceptional flexibility. In this context, the inventors of the present invention propose a particularly advantageous embodiment in which the bio-based polyamide yarns are combined with bio-based PET and / or recycled PET to form a reinforcing cord.Surprisingly, this combination of materials is not only particularly advantageous with regard to the sustainability of the manufacturing process and the reduction of resource dependence, but the performance of corresponding reinforcing cords and the composite materials produced with them is surprisingly not or only insignificantly worse compared to the use of petrochemically produced materials.A method according to the invention is therefore explicitly preferred, wherein the reinforcing cord comprises one or more further yarns made of materials selected from the group consisting of aramid, polyethylene terephthalate, polyetherketone, polyketone, polyethylene naphthalate, rayon, viscose, carbon fibers, natural fibers, glass fibers and PBO (poly(p-phenylene-2,6-benzobisoxazole)), preferably selected from the group consisting of aramid and polyethylene terephthalate, and particularly preferably selected from the group consisting of bio-based polyethylene terephthalate and recycled polyethylene terephthalate.

[0066] Within the scope of the present invention, the term "bio-based polyethylene terephthalate" means, in accordance with the preceding definition of bio-based polyamide, that the bio-based polyethylene terephthalate is produced by polymerization of monomers that are at least partially derived from biomass. In this context, at least the terephthalic acid or the ethylene glycol, preferably both the terephthalic acid and the ethylene glycol, is at least partially, and particularly preferably substantially completely, derived from biomass.

[0067] Within the scope of the present invention, the term "recycled polyethylene terephthalate" in accordance with the preceding definition of recycled polyamide refers to polyethylene terephthalate which has previously been processed into products and is intended for reuse in the recycling loop, and includes directly recycled polyethylene terephthalate and polyethylene terephthalate obtained from monomers obtained by depolymerization of old polyethylene terephthalate.

[0068] To obtain composite materials that are particularly suitable for the manufacture of pneumatic vehicle tires, it is often advantageous to completely embed the reinforcing cords in the vulcanizable rubber compound. The reinforcing cords can advantageously be used as individual strands or as woven fabrics. A preferred method according to the invention is therefore one in which the reinforcing cord is completely embedded, at least partially, in the vulcanizable rubber compound, so that the reinforcing cord is completely surrounded, at least partially, by the vulcanizable rubber compound. For certain applications, a further preferred method according to the invention is one in which the reinforcing cord is embedded in the vulcanizable rubber compound as a component of a woven fabric.

[0069] To optimize the properties of the composite materials produced using the inventive method, it has proven advantageous to also provide a coating for the reinforcing cords or the fabrics produced therefrom, which can be effectively achieved through hot drawing. Particularly when especially high proportions of bio-based polyamide and, optionally, particularly high proportions of recycled polyamide are used, the inventors consider the application of a high-performance adhesive impregnation particularly advisable in order to ensure high bond strength in the produced composite materials.A preferred method according to the invention further comprises, prior to process step c), the process step c0): c0) coating the reinforcing cord with a coating substance, wherein the coating of the reinforcing cord preferably involves hot drawing of the reinforcing cord, and / or wherein the coating substance is preferably selected from the group consisting of adhesion impregnations, particularly preferably selected from the group consisting of RFL dips comprising resorcinol, formaldehyde and latex, and aqueous dispersions, wherein the aqueous dispersions are essentially free of free resorcinol and resorcinol precondensates, in particular resorcinol-formaldehyde precondensates, and are free of free formaldehyde and formaldehyde-releasing substances.

[0070] A major advantage of the inventive method is its inherent flexibility with regard to the vulcanizable rubber compound used. Nevertheless, the inventors of the present invention have succeeded in identifying particularly suitable compositions.

[0071] A preferred method according to the invention is one in which the vulcanizable rubber mixture comprises at least one diene rubber, wherein the diene rubber is preferably selected from the group consisting of natural polyisoprene, synthetic polyisoprene, epoxidized polyisoprene, butadiene rubber, solution-polymerized styrene-butadiene rubber, emulsion-polymerized styrene-butadiene rubber, polynorbornene, ethylene propylene diene rubber, nitrile rubber, acrylate rubber, silicone rubber, polysulfide rubber, epichlorohydrin rubber, styrene-isoprene-butadiene terpolymer, hydrogenated acrylonitrile butadiene rubber, isoprene-butadiene copolymer, and hydrogenated styrene-butadiene rubber, wherein the diene rubber is particularly preferred. selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR),solution-polymerized styrene-butadiene rubber (SSBR) and emulsion-polymerized styrene-butadiene rubber (ESBR).

[0072] Furthermore, a method according to the invention is preferred, wherein the vulcanizable rubber mixture comprises 0.5 to 8.0 phr, preferably 0.5 to 4 phr, particularly preferably 0.5 to 2 phr, sulfur.

[0073] A preferred method according to the invention is also one in which the vulcanizable rubber mixture comprises 0.1 to 100 phr of one or more fillers, wherein the fillers are selected from the group consisting of polar and non-polar fillers, preferably selected from the group consisting of carbon black, aluminum hydroxide, titanium dioxide, magnesium oxide, amorphous silicon dioxide and layered silicates, particularly preferably selected from the group consisting of carbon black and amorphous silicon dioxide, wherein the vulcanizable rubber mixture most preferably comprises a polar filler and one or more silane compounds for binding the polar fillers.

[0074] A preferred method according to the invention is wherein the vulcanizable rubber mixture comprises one or more additives selected from the group consisting of reinforcing resins, methylene donors, coupling agents, adhesion promoters and plasticizers.

[0075] A preferred method according to the invention is also one in which the vulcanizable rubber mixture comprises one or more further additives selected from the group consisting of crosslinking agents, sulfur donors, accelerators, retarders, ozone protectants, anti-aging agents, masticating aids, processing aids and activators, wherein the total amount of the further additives is preferably up to 150 phr, preferably up to 100 phr, and particularly preferably 5 to 50 phr.

[0076] As explained above, the composite materials produced using the inventive method can advantageously be used to obtain particularly high-performance vehicle tires, the overall production of which is especially sustainable. This is achieved by combining the composite materials with other tire components to form a vehicle tire blank, which can then be vulcanized under normal conditions.

[0077] The invention therefore also relates to a method for manufacturing a vehicle tire, preferably a pneumatic vehicle tire, comprising the process steps of the inventive method for manufacturing a composite material, additionally comprising the process steps: d) Manufacturing a vehicle tire blank comprising the composite material, and e) Vulcanizing the vehicle tire blank to obtain a vulcanized vehicle tire.

[0078] A preferred method according to the invention is wherein the vehicle tire blank comprises the composite material as part of the carcass and / or as part of the belt and / or as a belt bandage and / or as a bead reinforcement, preferably as part of the carcass and / or as a belt bandage.

[0079] In light of the foregoing explanations of the inventive method and the high relevance of the specific reinforcing cords to be used in the inventive method, it is evident to the person skilled in the art that the present invention also relates to a reinforcing cord.

[0080] The invention thus also relates to a reinforcing cord for use as a strength carrier, in particular for application as a bead reinforcement, in the belt bandage, in the belt and / or in the carcass of vehicle tires, suitable for use in a method according to the invention, comprising at least one bio-based polyamide yarn containing bio-based polyamide, wherein the bio-based polyamide is at least partially composed of the starting monomers i) ε-Aminocaproic acid and / or ε-caprolactam, or ii) Hexamethylenediamine and hexamethylenedicarboxylic acid, is produced, whereby the starting monomers were at least partially produced from biomass, based on the amount of substance of the starting monomers.

[0081] The reinforcing cords according to the invention can be manufactured in a particularly sustainable manner, thereby reducing dependence on fossil raw materials in the production of vehicle tires. Furthermore, the reinforcing cords according to the invention surprisingly exhibit excellent physicochemical properties, which enable their processing into particularly high-performance composite materials or into advantageous vehicle tires.

[0082] In light of the foregoing, it is evident that reinforcing cords according to the invention are preferred which can be used in preferred methods according to the invention, each yielding the advantages described above.

[0083] A reinforcing cord according to the invention is therefore also preferred, wherein the bio-based polyamide is produced at least partially, preferably completely, from the starting monomers ε-aminocaproic acid and / or ε-caprolactam, preferably ε-caprolactam.

[0084] A reinforcing cord according to the invention is therefore also preferred, wherein the bio-based polyamide is produced at least partially, preferably completely, from the starting monomers hexamethylenediamine and hexamethylenedicarboxylic acid.

[0085] A reinforcing chord according to the invention is also preferred, wherein the hexamethylenediamine is 1,6-diaminohexane and / or wherein the hexamethylenedicarboxylic acid is 1,6-hexanedioic acid.

[0086] A reinforcement cord according to the invention is also preferred, wherein the starting monomers were at least partially produced by the reaction of 5-(hydroxymethyl)furfural, wherein the 5-(hydroxymethyl)furfural was produced from biomass.

[0087] A reinforcement cord according to the invention is therefore also preferred, wherein the biomass is selected from the group consisting of plant and animal biomass, preferably selected from the group consisting of plant biomass, and particularly preferably selected from the group consisting of cereal plants.

[0088] A reinforcement cord according to the invention is therefore also preferred, wherein the starting monomers are produced from biomass to 40% or more, preferably 70% or more, particularly preferably 90% or more, very preferably 95% or more, further preferably 99% or more, and in particular preferably essentially completely, based on the amount of substance of the starting monomers.

[0089] A reinforcing cord according to the invention is therefore also preferred, wherein the starting monomers are at least partially produced from petroleum, based on the amount of substance of the starting monomers.

[0090] A reinforcing cord according to the invention is therefore also preferred, wherein the starting monomers are produced from petroleum to 0.1 to 60%, preferably to 0.2 to 30%, particularly preferably to 0.5 to 10%, and most preferably to 1 to 5%, based on the amount of substance of the starting monomers.

[0091] A reinforcing cord according to the invention is also preferred, wherein the starting monomers are at least partially produced by depolymerization of recycled polyamide, based on the amount of substance of the starting monomers.

[0092] A preferred reinforcing cord according to the invention is therefore also preferred, wherein the starting monomers are produced by depolymerization of recycled polyamide to a concentration of 0.1 to 60%, preferably 0.2 to 30%, particularly preferably 0.5 to 10%, and most preferably 1 to 5%, based on the amount of substance of the starting monomers.

[0093] A reinforcing cord according to the invention is also preferred, wherein the starting monomers are produced to 40% or more, preferably 70% or more, particularly preferably 90% or more, most preferably 95% or more from biomass, to 0.1 to 59.9%, preferably 0.2 to 29.8%, particularly preferably 0.5 to 9.5%, most preferably 1 to 4% from petroleum, and to 0.1 to 49.9%, preferably 0.2 to 29.8%, particularly preferably 0.5 to 9.5%, most preferably 1 to 4% by depolymerization of recycled polyamide, based on the amount of substance of the starting monomers.

[0094] A reinforcing cord according to the invention is also preferred, wherein the bio-based polyamide yarn comprises the bio-based polyamide in a mass fraction of 40% or more, preferably 70% or more, particularly preferably 90% or more, most preferably 95% or more, further preferably 99% or more, based on the mass of the bio-based polyamide yarn, wherein the bio-based polyamide yarn particularly preferably consists of the bio-based polyamide.

[0095] A reinforcement cord according to the invention is therefore also preferred, wherein the bio-based polyamide yarn additionally comprises petroleum-based polyamide, which is produced from petroleum.

[0096] A reinforcement cord according to the invention is therefore also preferred, wherein the bio-based polyamide yarn comprises petroleum-based polyamide in a mass fraction in the range of 0.1 to 60%, preferably in the range of 0.2 to 30%, particularly preferably in the range of 0.5 to 10%, and most preferably in the range of 1 to 5%, based on the mass of the polyamide yarn.

[0097] A reinforcement cord according to the invention is also preferred, wherein the bio-based polyamide yarn additionally comprises recycled polyamide, which is produced by recycling polyamide-containing products.

[0098] A reinforcement cord according to the invention is therefore also preferred, wherein the bio-based polyamide yarn comprises recycled polyamide in a mass fraction in the range of 0.1 to 60%, preferably in the range of 0.2 to 30%, particularly preferably in the range of 0.5 to 10%, and most preferably in the range of 1 to 5%, based on the mass of the bio-based polyamide yarn.

[0099] A preferred reinforcement cord according to the invention is therefore also a bio-based polyamide yarn, wherein the bio-based polyamide yarn comprises the bio-based polyamide in a mass fraction of 40% or more, preferably 70% or more, particularly preferably 90% or more, and most preferably 95% or more, the petroleum-based polyamide in a mass fraction in the range of 0.1 to 60%, preferably in the range of 0.2 to 30%, particularly preferably in the range of 0.5 to 10%, and most preferably in the range of 1 to 5%, and the recycled polyamide in a mass fraction in the range of 0.1 to 60%, preferably in the range of 0.2 to 30%, particularly preferably in the range of 0.5 to 10%, and most preferably in the range of 1 to 5%, in each case based on the mass of the bio-based polyamide yarn.

[0100] A reinforcement cord according to the invention is therefore also preferred, wherein the bio-based polyamide and / or the petroleum-based polyamide and / or the recycled polyamide, preferably all polyamides, are PA6 or PA6.6, preferably PA6.6.

[0101] A reinforcing cord according to the invention is also preferred, wherein the polyamide yarn has a fineness in the range of 200 to 5000 dtex, preferably in the range of 300 to 2000 dtex or in the range of 1700 to 4500 dtex, particularly preferably in the range of 400 to 1900 dtex or in the range of 1800 to 2500 dtex.

[0102] Furthermore, a reinforcing cord according to the invention is also preferred, wherein the polyamide yarn is twisted with 100 to 600 T / m, preferably with 150 to 550 T / m, particularly preferably with 200 to 500 T / m.

[0103] A reinforcing cord according to the invention is also preferred, wherein the reinforcing cord comprises two or more yarns, wherein the yarns in the reinforcing cord are preferably twisted together at the ends with 100 to 600 T / m, particularly preferably with 150 to 550 T / m, and most preferably with 200 to 500 T / m.

[0104] A reinforcement cord according to the invention is also preferred, wherein all yarns in the reinforcement cord have a fineness in the range of 200 to 5000 dtex, preferably in the range of 300 to 2000 dtex or in the range of 1700 to 4500 dtex, particularly preferably in the range of 400 to 1900 dtex or in the range of 1800 to 2500 dtex.

[0105] A reinforcement cord according to the invention is therefore also preferred, wherein the reinforcement cord has a total fineness in the range of 400 to 10000 dtex, preferably in the range of 600 to 7500 dtex, particularly preferably in the range of 800 to 5000 dtex.

[0106] A reinforcement cord according to the invention is therefore also preferred, wherein 30% or more, preferably 50% or more, particularly preferably 70% or more, most preferably 90% or more, and in particular preferably essentially all, of the yarns contained in the reinforcement cord are bio-based polyamide yarns.

[0107] A reinforcement cord according to the invention is therefore also preferred, wherein the reinforcement cord comprises one or more further yarns made of materials selected from the group consisting of aramid, polyethylene terephthalate, polyetherketone, polyketone, polyethylene naphthalate, rayon, viscose, natural fibers and glass fibers, preferably selected from the group consisting of aramid and polyethylene terephthalate, and particularly preferably selected from the group consisting of bio-based polyethylene terephthalate.

[0108] The invention further relates to a composite material for the manufacture of vehicle tires, preferably manufactured or manufacturable using the inventive method, comprising: x) a vulcanizable rubber compound, and y) one or more reinforcing cords according to the invention embedded in the vulcanizable rubber compound.

[0109] A composite material according to the invention is preferred, wherein the reinforcing cord is at least partially completely embedded in the vulcanizable rubber mixture, so that the reinforcing cord is at least partially completely surrounded by the vulcanizable rubber mixture.

[0110] The invention also relates to a vehicle tire, in particular a pneumatic vehicle tire, preferably manufactured or manufacturable using the inventive method, comprising a vulcanized composite material according to the invention. Preferably, the vehicle tire according to the invention comprises the vulcanized composite material according to the invention as part of the carcass and / or as a belt band.

[0111] The composite material and the vehicle tire according to the invention offer the advantages disclosed above for the method according to the invention.

[0112] Finally, the invention relates to the use of a reinforcing cord or a composite material according to the invention in the manufacture of vehicle tires to reduce the need for fossil resources. Example A:

[0113] As a particularly advantageous embodiment of the invention, the inventors propose the following method according to the invention.

[0114] 5-(Hydromethyl)furfural is provided, which is obtained from high-fructose corn syrup. Starting with this material, it is reacted to form 1,6-diaminohexane and 1,6-hexanedioic acid, which, after purification in process step a), are used as starting monomers.

[0115] The starting composition contains the corresponding starting monomers essentially in stoichiometric proportions, whereby, due to the manufacturing process, virtually all of the starting monomers in the starting composition are produced from biomass. This starting composition is polymerized to form the polyamide PA6.6, with the production proceeding via the intermediate hexamethylenediamine adipate ("AH salt"). The polyamide PA6.6 is then processed into a polyamide yarn using a melt spinning process. The polyamide yarn has a fineness of 1400 dtex.

[0116] Two of these bio-based polyamide yarns are then twisted together with a twist factor of 150, resulting in a total fineness of 2800 dtex (1400 x 2) for the reinforcing cord, making it particularly suitable for use in a belt bandage. The resulting reinforcing cords are then embedded in a vulcanizable rubber compound by calendering, so that they are essentially completely surrounded by the vulcanizable rubber compound in the resulting composite material. For this purpose, the reinforcing cords are first coated with an RFL dip as an adhesive impregnation.

[0117] The vulcanizable rubber compound used comprises 100 phr polyisoprene, 65 phr carbon black, 1.5 phr sulfur, 4 phr of a reinforcing resin, 4 phr zinc oxide, 3 phr antioxidant, 0.5 phr stearic acid and 1 phr accelerator DCBS.

[0118] The vulcanizable composite material produced in this way can then be assembled with other components to form a vehicle tire blank, from which a vehicle tire can be obtained through vulcanization. Example B:

[0119] As an advantageous modification of the exemplary process A described above, it is proposed to change the composition of the starting material in process step a). Exemplary variants include starting material compositions in which the starting monomers are produced from 95% biomass and 5% petroleum. Alternatively, the starting monomers are produced, for example, from 80% biomass and 20% by depolymerization of recycled polyamide. As a particularly preferred example, the starting monomers are produced from 94% biomass, 4% by depolymerization of recycled polyamide, and 2% petroleum. Example C:

[0120] As a further advantageous modification of the exemplary processes A and B described above, the exemplary process is modified such that in process step b), the polyamide is mixed with other polyamides during the forming of the bio-based polyamide yarn, which can be done, for example, in an extruder. This can be done, for example, such that the mass fraction of bio-based polyamide is 97% and the mass fraction of petroleum-based polyamide is 3%. Alternatively, the mass fraction of bio-based polyamide can be set to, for example, 74%, with the remaining 26% being made up of recycled polyamide, which is obtained, for example, by recycling polyamide textiles. In a particularly preferred exemplary embodiment, the bio-based polyamide yarn comprises 75% bio-based polyamide, 20% recycled polyamide, and 5% petroleum-based polyamide. Example D:

[0121] As a further advantageous modification of the exemplary methods AB and C described above, it is proposed to replace one of the bio-based polyamide yarns in each of the reinforcing cords with an aramid yarn or a PET yarn. In a particularly advantageous further development of this example, the PET yarn is a PET yarn made from recycled PET or which is at least partially produced from biomass.

Claims

1. Process for producing a composite material for use in the production of vehicle tyres comprising the process steps of: a) producing or providing a starting composition comprising as starting monomers: i) ε-aminocaproic acid and / or ε-caprolactam and / or ii) hexamethylenediamine and hexamethylenedicarboxylic acid, wherein the starting monomers present in the starting composition are at least partially produced from biomass based on the amount of substance of the starting monomers present in the starting composition, b) polymerizing the starting monomers present in the starting composition to afford a biobased polyamide, forming the biobased polyamide into a biobased polyamide yarn and processing the biobased polyamide yarn into a reinforcing cord and c) embedding the reinforcing cord in a vulcanizable rubber mixture to obtain the composite material.

2. Process according to Claim 1, wherein the starting monomers present in the starting composition are produced to an extent of 40% or more from biomass based on the amount of substance of the starting monomers present in the starting composition.

3. Process according to either of Claims 1 or 2, wherein the starting monomers present in the starting composition are at least partially produced from petroleum and / or wherein the starting monomers present in the starting composition are at least partially produced by depolymerization of recycled polyamide.

4. Process according to any of Claims 1 to 3, wherein the biobased polyamide yarn comprises the biobased polyamide in a mass fraction of 40% or more based on the mass of the biobased polyamide yarn.

5. Process according to any of Claims 1 to 4, wherein the biobased polyamide yarn additionally comprises petroleum-based polyamide which is produced from petroleum and / or wherein the biobased polyamide yarn additionally comprises recycled polyamide produced by recycling polyamide-containing products.

6. Process according to any of Claims 1 to 5, wherein the reinforcing cord comprises one or more further yarns composed of materials selected from the group consisting of aramid, polyethylene terephthalate, polyether ketone, polyketone, polyethylene naphthalate, rayon, viscose, carbon fibres, natural fibres, glass fibres and poly(p-phenylene-2,6-benzobisoxazole), preferably selected from the group consisting of aramid and polyethylene terephthalate, particularly preferably selected from the group consisting of biobased polyethylene terephthalate and recycled polyethylene terephthalate.

7. Process for producing a vehicle tyre, preferably a pneumatic vehicle tyre, comprising the process steps of the process according to any of Claims 1 to 6 and additionally comprising the process steps: d) producing a green vehicle tyre comprising the composite material and e) vulcanizing the green vehicle tyre to obtain a vulcanized vehicle tyre.

8. Reinforcing cord for use as a strength member, in particular for application as a bead reinforcer, in the belt bandage, in the belt and / or in the carcass of vehicle tyres, suitable for use in a process according to any of Claims 1 to 7 comprising at least one biobased polyamide yarn containing biobased polyamide, wherein the biobased polyamide was at least partially produced from the starting monomers i) ε-aminocaproic acid and / or ε-caprolactam or ii) hexamethylenediamine and hexamethylenedicarboxylic acid, wherein the starting monomers have been at least partially produced from biomass.

9. Composite material for producing vehicle tyres comprising: x) a vulcanizable rubber mixture and y) one or more reinforcing cords according to Claim 8 embedded in the vulcanizable rubber mixture.

10. Vehicle tyre, in particular pneumatic vehicle tyre, comprising a vulcanized composite material according to Claim 9.