METHOD FOR MODIFYING CABLE CORE FOR TIRE PRODUCTION AND CABLE CORE

Description

[0001] The invention relates to a method for modifying a cable core, in particular for use in tire manufacturing, a method based thereon for manufacturing a vehicle tire, corresponding modified cable cores, rubber products, in particular vehicle tires, comprising these modified cable cores, and the use of non-metallic reinforcing strips to improve the adhesion of rubber materials to cable cores.

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

[0003] In the production of modern pneumatic tires, so-called cable cores are regularly used, particularly in the bead of the tire. Cable cores are familiar to those in the field. They are strand-like products in which a central core filament is surrounded by usually several layers of filaments, each arranged around the core filament or beneath the layer below it. The filaments in each layer lie parallel to each other and are typically twisted or wound around the layer below in a spiral. In cable cores, the filaments of a layer are usually packed closely together, so that from the outside only the outermost layer is typically visible.

[0004] In order to obtain pneumatic tires in later tire production that remain reliably on the rim even under high loads, it is regularly necessary that the cable cores used in the vulcanized vehicle tire form a firm bond with the surrounding rubber material.

[0005] It is known to those skilled in the art that the adhesive interaction between vulcanizable rubber compounds or the rubber materials produced from them with the cable cores, which are usually made of metal, is in many cases insufficient, so that without further measures, material defects can occur under heavy load, and in some cases even the production of a firm bond between the rubber material and the cable core can be difficult.

[0006] To solve this problem, adhesion promoters have typically been used, for example, as an additive to the rubber compound and / or as a coating on the cable cores. However, the use of such adhesion promoters is regularly perceived as disadvantageous. With some solutions known from the prior art, the bond strength achieved between the cable core and the rubber material by the adhesion promoter is considered insufficient. However, in most cases, and especially with many of the known high-performance adhesion promoters, the far more serious issue is that these substances are often harmful to health and can therefore expose the workers involved in production to health risks and / or pollute the environment.

[0007] Examples of the coating of cable cores, particularly for tires, are disclosed in JP 2002088668 A1, EP 3875678 A1 and DE 4125887 A1. Further information on the technological background is disclosed in AT 395732 B, US 2004 / 166299 A1, EP 2000585 A1, US 2013 / 220505 A1 and WO 2019 / 015792 A1.

[0008] Against the backdrop of increasing awareness of sustainable economic practices, many countries are also tending to prohibit or at least limit the use of corresponding adhesion promoters that are harmful to health and / or the environment, and it cannot be ruled out that in the long term all of the adhesion promoters known to be effective according to the state of the art will no longer be able to be used in significant parts of the world.

[0009] To create an alternative to the known adhesion promoters, attempts were made, for example, to wrap cable cores with fabrics to increase the bond strength, but these approaches were often found to be inadequate with regard to the bond strength to be achieved and the manufacturing effort involved in wrapping the cable core with the fabric.

[0010] The object of the present invention was to eliminate or at least reduce the disadvantages of the prior art described above.

[0011] In particular, it was an object of the present invention to provide a method for modifying a cable core with which modified cable cores can be obtained which, when used in rubber products, have excellent bond strength with the surrounding rubber material.

[0012] In this respect, it was a requirement that the specified process should do without the use of harmful substances and, in particular, should not require conventional coatings as adhesion promoters.

[0013] Against this background, it was an objective of the present invention that the specified process should be particularly reliable and that the health and environmental impact should be as low as possible.

[0014] One object of the present invention was to ensure that the cable cores produced by the specified method could be manufactured flexibly, so that the specified method could be flexibly adapted to the respective process conditions in tire manufacturing. Against this background, a complementary object was that the specified method should be efficiently integrable into existing tire manufacturing processes.

[0015] The procedure to be specified stipulated that ideally only materials should be used which the expert in the field of tire manufacturing already has available from other manufacturing steps.

[0016] It was a supplementary objective of the present invention that the specified method should ideally be particularly cost- and time-efficient, so that in particular its use in the mass production of passenger car tires on an industrial scale becomes possible.

[0017] In light of the above objectives, a supplementary objective of the present invention was to provide, based on the method to be specified, a method for the manufacture of vehicle tires which includes the step of modifying the cable core.

[0018] It is evident to the person skilled in the art that a further object of the present invention is to provide a modified cable core which, when used in the manufacture of rubber products, achieves a particularly high bond strength with the rubber material even without the use of harmful adhesion promoters.

[0019] Accordingly, a secondary object of the present invention was also to specify a rubber product, in particular a vehicle tire, comprising the modified cable cores to be specified.

[0020] Furthermore, it was an object of the present invention to specify a use of non-metallic reinforcing strips in the modification of cable cores.

[0021] The inventors of the present invention have now realized that the problems described above can be solved by utilizing the grooves present on the surface of cable cores to place non-metallic reinforcing strips in them, as defined in the claims. This surprisingly makes it possible to obtain a modified cable core that exhibits excellent adhesion to rubber materials without the need for additional adhesion promoters.

[0022] 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.

[0023] 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 modified cable cores, rubber products, vehicle tires, and uses result from the features of preferred methods.

[0024] The invention relates to a method for modifying a cable core, in particular for use in tire manufacturing, comprising the following process steps: v1) Manufacturing or providing a cable core comprising a core filament and at least one filament layer arranged around the core filament, comprising a plurality of outer filaments, wherein the surface of the cable core has a plurality of grooves formed by the outer filaments of the outermost filament layer; v2) Manufacturing or providing one or more non-metallic reinforcing strips, wherein at least one non-metallic reinforcing strip is selected from the group consisting of coated fibers and rubber strips, comprising a vulcanizable rubber compound; and v3) Arranging the one or more non-metallic reinforcing strips in one or more of the grooves of the surface of the cable core to obtain a modified cable core, wherein the one or more non-metallic reinforcing strips are wound around the outer filament layer of the cable core.that these are arranged in the grooves of the cable core's surface.

[0025] The method according to the invention is directed towards the modification of cable cores. These cable cores are suitable for use in tire manufacturing, which also makes the method for modifying the cable cores itself particularly suitable for use in tire manufacturing. However, it should be noted that the method according to the invention and the modified cable cores that can be produced with it are, in principle, advantageous for all applications in which cable cores are to be incorporated into a rubber material.

[0026] In process step v1), a cable core is first manufactured or provided. In accordance with the skilled person's understanding, such a cable core comprises at least one core filament, preferably exactly one core filament, and several filament layers wound around the core filament, each layer comprising a plurality, i.e., two or more, filaments, wherein these filaments of the filament layers are referred to as outer filaments in contrast to the core filament. In most cases, a method according to the invention is preferred, wherein the outer filaments of at least one of the filament layers, preferably at least the outermost filament layer, and particularly preferably all filament layers, are wound around the core filament or the respective underlying filament layer, wherein the filament layers are preferably S- or Z-twisted.

[0027] It is evident to those skilled in the art that the surface structure of corresponding cable cores is essentially determined by the outermost filament layer. The outer filaments of the outermost filament layer run essentially parallel to one another, and in most industrially relevant cable cores, the outer filaments also touch their respective neighbors. This results in the outer filaments forming a multitude of grooves, i.e., depressions, on the surface of the cable core, which run regularly around the entire length of the cable core, parallel to the outer filaments. In accordance with the understanding of those skilled in the art, the term "grooves" within the scope of the present invention refers only to the grooves located on the surface of the cable core and not to any spaces between the outer filaments of two adjacent filament layers or between the outer filaments of a filament layer and the inner core filament.

[0028] The inventors of the present invention have recognized that, surprisingly, these grooves can be used to obtain a modified cable core which has excellent adhesion properties to rubber materials. For this purpose, in step v2) of the inventive method, it is necessary to produce or provide one or more reinforcing strips, which must be non-metallic reinforcing strips.

[0029] In the inventive method, these non-metallic reinforcing strips are arranged in the grooves of the cable core's surface, i.e., at specific locations on the cable core, to obtain a modified cable core. This allows for the efficient production of a modified cable core whose adhesion to rubber materials is improved by the non-metallic components on its surface, i.e., in the relevant contact area with the rubber material, since such non-metallic components, unlike metals, typically exhibit significantly better adhesion to rubber materials.

[0030] The arrangement of the non-metallic reinforcing strips in the grooves initially ensures a large contact area between the outer filaments and the non-metallic reinforcing strip. This results in particularly good adhesion of the non-metallic reinforcing strips to the surface of the cable core, for example, when using rubber-containing reinforcing strips. At the same time, the arrangement in the grooves of the cable core's surface, i.e., along the grooves of the cable core's surface, allows the non-metallic reinforcing strips to be fixed in place, preventing them from slipping along the cable core. The wrapping of the non-metallic reinforcing strips around the core filament in the grooves creates an additional mechanical connection between the non-metallic reinforcing strips and the cable core.

[0031] This is a method according to the invention, wherein one or more non-metallic reinforcing strips are wound around the outer filament layer of the cable core in such a way that they are arranged in the grooves of the surface of the cable core.

[0032] A preferred method according to the invention is one or more non-metallic reinforcing strips arranged in the grooves of the surface of the cable core over the entire length of the cable core.

[0033] A preferred method according to the invention is also one in which the arrangement of one or more non-metallic reinforcing strips in the grooves of the surface of the cable core is such that the non-metallic reinforcing strips run essentially parallel to the outer filaments of the outermost filament layer.

[0034] According to the inventors, there are two particularly promising procedures for the process step v3) of ordering.

[0035] In a particularly preferred embodiment, which in most cases is probably only accessible to users who have the manufacturing capabilities to produce cable cores themselves, the non-metallic reinforcing strips are arranged in the grooves of the cable core surface during the core's production. In this process, the arrangement occurs simultaneously with the creation of the outer filament layer, for example, by wrapping the non-metallic reinforcing strips around the core filament or the outer filaments of the underlying filament layer together with the outer filaments of the outermost filament layer, so that they are arranged in the grooves.This not only enables a particularly cost- and time-efficient process, but according to the inventors, it also allows for the production of particularly advantageous modified cable cores. This is because the process can result in a particularly close bond between the non-metallic reinforcing strips and the outer filaments of the outermost filament layer, especially when the non-metallic reinforcing strips are partially clamped and thus fixed between the outer filaments. Due to the inherently strong bond between the non-metallic reinforcing strips and the cable core, a particularly high bond strength of the overall assembly can also be achieved during further processing.A preferred method according to the invention is therefore one in which the cable core is produced in process step v1), wherein the production is carried out by winding the outer filaments of the outermost filament layer around the core filament or around the outer filaments of the underlying filament layer, wherein the arrangement of one or more non-metallic reinforcing strips in the grooves of the surface of the cable core is carried out simultaneously with the winding of the outer filaments of the outermost filament layer.

[0036] As an alternative to the method described above, a method according to the invention can be seen in which the arrangement of the non-metallic reinforcing strips takes place only subsequently in an already manufactured cable core, for example by wrapping it with the non-metallic reinforcing strips in such a way that they are arranged in the grooves and the winding creates an additional mechanical connection between the non-metallic reinforcing strip and the cable core.According to the inventors, this method may, in some cases, result in a lower bond strength between the non-metallic reinforcing strips and the cable core than the incorporation described above during manufacturing. However, the inventors consider this method to be significantly simpler and generally requires less equipment, particularly because the cable cores can be sourced from external suppliers and do not need to be manufactured in-house. Therefore, a preferred alternative method according to the invention is one in which the arrangement of the one or more non-metallic reinforcing strips in the grooves of the cable core surface takes place after the cable core has been manufactured or provided.

[0037] According to the inventors of the present invention, a wide range of non-metallic reinforcing strips can advantageously be used in the inventive method, and the modified cable cores thus obtained, which comprise metallic and non-metallic components, exhibit, in the inventors' opinion, essentially better adhesion to rubber materials in all cases than the insulated metallic cable cores. Nevertheless, the inventors of the present invention have succeeded in identifying particularly suitable materials for the non-metallic reinforcing strips, with which modified reinforcing cords with excellent properties can be obtained. The preferred materials were chosen particularly because of their advantageous processing properties. In addition to particularly suitable material classes, particularly advantageous materials were also identified within each of the respective classes.Therefore, it is particularly advantageous if the non-metallic reinforcing strips are made of the respective materials. According to the invention, a method according to the invention is, wherein at least one non-metallic reinforcing strip, preferably all non-metallic reinforcing strips, is selected from the group consisting of coated fibers, in particular glass fibers, natural fibers and plastic fibers, and rubber strips comprising a vulcanizable rubber compound, preferably selected from the group consisting of fibers coated with carbon black, with a vulcanizable rubber compound or with an adhesive activation, in particular natural fibers or plastic fibers, and rubber strips comprising a vulcanizable rubber compound, particularly preferably selected from the group consisting of plastic fibers coated with carbon black, in particular polyester fibers and nylon fibers, plastic fibers coated with an adhesive activation, in particular polyester fibers and nylon fibers, and rubber strips comprising a vulcanizable rubber compound.The adhesive is particularly preferably selected from the group consisting of plastic fibers coated with an adhesive activation agent, in particular polyester fibers and nylon fibers, and rubber strips comprising a vulcanizable rubber compound, wherein the adhesive activation agent is preferably selected from the group consisting of RFL dips comprising resorcinol, formaldehyde and latex, and aqueous dispersions, wherein the aqueous dispersions are substantially free of free resorcinol and resorcinol precondensates, in particular resorcinol-formaldehyde precondensates, and are free of free formaldehyde and formaldehyde-releasing substances.

[0038] In accordance with the skilled person's understanding, the preferred embodiment in the case of coated fibers also includes the use of coated yarns or fabrics of corresponding fibers.

[0039] According to the inventors, coated fibers are particularly suitable for the inventive method, as they are superior to uncoated fibers with regard to the adhesion of the modified cable core to rubber materials, as are unvulcanized rubber strips, i.e. strand-shaped material strips comprising a vulcanizable rubber mixture.

[0040] Besides carbon black coatings, coatings made of a vulcanizable rubber compound have proven to be particularly preferred coatings for the fibers. Those skilled in the art will recognize that with fibers coated with a vulcanizable rubber compound, the circle closes back to the equally preferred rubber strips. However, fibers coated with a specific adhesive activation agent can be considered a particularly preferred embodiment. Such adhesive activation agents for fibers are known to those skilled in the art, with so-called RFL dips, comprising resorcinol, formaldehyde, and latex, being used in particular. According to the inventors, such adhesive activation agents for fibers lead to particularly strong bonds due to the exceptionally high adhesion of the fibers and the specific compatibility with conventional rubber compounds.Despite the familiarity of RFL dips, the inventors believe that the use of certain aqueous dispersions is particularly advantageous. These dispersions have proven to be a more environmentally friendly and less harmful alternative to RFL dips and are disclosed, for example, in WO 2019 / 015792 A1, EP 3702521 A1, EP 3702522 A1, and EP 3702523 A1. Among the fibers, plastic fibers such as polyester fibers (e.g., polyethylene terephthalate) and nylon fibers are particularly preferred.

[0041] In light of the foregoing, it is evident to those skilled in the art that such non-metallic reinforcing strips, comprising a vulcanizable rubber compound, for example in the form of a fiber coated with a vulcanizable rubber compound, can be considered advantageous for many embodiments of the method according to the invention. One reason for this preference is that, after application, such non-metallic reinforcing strips can be further shaped in the grooves of the surface of the modified cable core, for example by pressing them into the grooves to maximize the contact area, thereby advantageously producing a smoother surface of the modified cable core. This improves the adhesion between the non-metallic reinforcing strips and the cable core.Furthermore, it is also possible to largely encase the exposed metallic components on the surface of the cable core with the vulcanizable rubber compound, thus reducing the exposed surface area of ​​these metallic regions, which are generally less compatible with the rubber materials used in rubber products. In a particularly preferred embodiment, the forming process can be carried out by guiding a cable core, in whose grooves corresponding non-metallic reinforcing strips with a vulcanizable rubber compound are arranged, through a forming tool with an annular recess, for example, a tube, the inner diameter of which is dimensioned such that the non-metallic reinforcing strips are pressed into the grooves, resulting in a modified cable core whose outer shape is essentially determined by the shape of the annular recess.A preferred method according to the invention is wherein at least one non-metallic reinforcing strip, preferably all non-metallic reinforcing strips, comprises a vulcanizable rubber compound, wherein the method additionally comprises the following process step: . v4) Forming the non-metallic reinforcing strips arranged in the grooves of the surface of the modified cable core to adapt the non-metallic reinforcing strips to the shape of the grooves and / or to produce a smoother surface of the modified cable core and / or to at least partially encase, preferably completely encase, the cable core with the vulcanizable rubber compound, wherein the forming is preferably carried out with a forming tool, wherein the forming is particularly preferably carried out by guiding the modified cable core through a forming tool with an annular recess, the inner diameter of which corresponds substantially to the envelope of the cross-section of the cable core.

[0042] For certain applications, it can be advantageous if the core filament itself is multi-part, with these parts regularly joined by a metallurgical bond. In this case, a method according to the invention is preferred, wherein the core filament comprises two or more twisted sub-filaments, the sub-filaments preferably being metallurgically bonded to one another, preferably by a welding process.

[0043] Although the inventive method can be used for cable cores with only one outer filament layer, structures with multiple filament layers are generally preferred with regard to the mechanical properties of the cable cores. A preferred method according to the invention is one in which two or more, preferably three or more, filament layers are arranged around the core filament, one above the other in a radial direction.

[0044] The number of outer filaments per filament layer is essentially determined by the number of filament layers and the diameter of the individual outer filaments, with a higher number of filament layers in the outermost filament layer generally resulting in a higher number of outer filaments. However, a method according to the invention is preferred in which the outermost filament layer comprises 6 or more, preferably 8 or more, particularly preferably 12 or more, and most preferably 16 or more, outer filaments.

[0045] Although it would be possible in principle to avoid butting the outer filaments of the outermost filament layer, this is generally not preferred, particularly with regard to the manufacturing process and the durability of the resulting cable core, at least not if the non-metallic reinforcing strips are not directly arranged in the spaces between the outer filaments, as disclosed above for the preferred method of manufacturing modified cable cores. Therefore, a method according to the invention is preferred in most cases, wherein the outer filaments of the outermost filament layer touch their respective neighbors, resulting in a dense filament layer and the one or more non-metallic reinforcing strips not touching the core filament or the inner filament layers.

[0046] Although it is theoretically possible to manufacture cable cores from other materials, the vast majority of relevant applications are assumed to involve cable cores that consist of a metallic material, at least with regard to the outer filaments of the outermost layer. This is particularly true because the problem of reduced adhesion to rubber materials is generally less pronounced with other cable cores. According to the inventors of the present invention, particularly advantageous modified cable cores can be obtained synergistically if the metallic parts are provided with a copper-based coating, as this improves adhesion to the non-metallic reinforcing strips.Therefore, in most cases a method according to the invention is preferred, wherein the core filament and / or the outer filaments, preferably all filaments, are made of a metallic material, preferably steel, wherein the core filament and / or the outer filaments, preferably the outer filaments of the outermost filament layer, are coated with copper and / or a copper alloy.

[0047] The non-metallic reinforcing strips used in the inventive method can be manufactured or provided. Manufacturing is preferred over providing, for example, by purchasing from a supplier, particularly when these materials are to be incorporated during the manufacture of the cable core. In all cases, manufacturing can preferably be carried out by dip coating of fibers or by extrusion of a vulcanizable rubber compound in strip form, i.e., as a strand-like material. A preferred method according to the invention is therefore one in which the one or more non-metallic reinforcing strips are manufactured by dip coating or extrusion, preferably by dip coating of a fiber with carbon black or an adhesive activation agent, or by extrusion of a vulcanizable rubber compound.

[0048] It can be seen as an advantage of the method according to the invention that the extent of the modification can be adapted to the specific needs of the later application. However, in the inventors' opinion, it is particularly preferred if a separate non-metallic reinforcing strip is arranged in each groove of the surface of the cable core. Accordingly, a method according to the invention is preferred in which a separate non-metallic reinforcing strip is arranged in each groove of the surface of the cable core.

[0049] According to the inventors, particularly interesting and versatile adhesion properties of the cable cords arise especially when the grooves are not continuously filled with the same non-metallic reinforcing strips, but rather with adjacent reinforcing strips made of different materials. A preferred method according to the invention is therefore one in which a non-metallic reinforcing strip is arranged in each of two adjacent grooves on the surface of the cable core, wherein the non-metallic reinforcing strips consist of different materials.

[0050] The inventors of the present invention have succeeded in identifying particularly preferred parameters for the non-metallic reinforcing strips and their arrangement to be used in the inventive method.

[0051] A preferred method according to the invention is one in which the non-metallic reinforcing strips have a diameter in the range of 0.05 to 2.0 mm, preferably in the range of 0.1 to 1.5 mm, and particularly preferably in the range of 0.15 to 1.0 mm, and / or in which the non-metallic reinforcing strips do not touch each other in the modified cable core. A preferred method according to the invention is one in which the arrangement of the one or more non-metallic reinforcing strips in the grooves of the surface of the cable core is such that a non-metallic reinforcing strip is arranged in at least 40%, preferably at least 60%, particularly preferably at least 80%, and most preferably at least 90% of the grooves.

[0052] In addition to the foregoing, the inventors of the present invention have also succeeded in identifying a particularly advantageous structure for the cable core to be used in the inventive method, which harmonizes particularly well with the non-metallic reinforcing strips to be applied in the inventive method and with which particularly high-performance modified cable cores can be obtained, which are particularly suitable for use in vehicle pneumatic tires.A preferred method according to the invention is wherein the core filament has a diameter in the range of 0.5 to 8.5 mm, preferably in the range of 0.8 to 7.5 mm, particularly preferably in the range of 1.0 to 6.5 mm, and / or wherein the outer filaments have a diameter in the range of 0.30 to 4.0 mm, preferably in the range of 0.5 to 3.5 mm, particularly preferably in the range of 0.6 to 3.0 mm, and / or wherein the cable core has a diameter in the range of 0.8 to 45.0 mm, preferably in the range of 1.3 to 40.0 mm, particularly preferably in the range of 1.8 to 38.0 mm.

[0053] The invention also relates to a method for manufacturing a vehicle tire, in particular a pneumatic vehicle tire, comprising the process steps of the inventive method for modifying cable cores, as well as the process steps: v5) Manufacturing a tire blank comprising the modified cable core in at least one component, preferably in the tire bead, particularly preferably as a bead core, wherein the modified cable core in the tire blank is at least partially surrounded by a crosslinkable rubber compound, and v6) vulcanizing the tire blank to manufacture a vehicle tire, preferably in a vulcanization mold.

[0054] The inventive method for manufacturing a vehicle tire is preferred because, by using the modified cable cores produced with the inventive method and processing them in a tire blank by means of vulcanization, vehicle tires can be obtained in which the cable core has a particularly strong and durable connection to the surrounding rubber material, so that, for example, the corresponding vehicle tires with an inventive modified cable core in the bead area remain reliably on the rim even under strong mechanical stress.

[0055] In principle, an advantage of the inventive method is that modified cable cores can be produced using the inventive method, exhibiting substantially improved adhesion compared to all crosslinkable rubber compounds used in the tire blank and the rubber materials produced therefrom. Nevertheless, the inventors of the present invention propose particularly suitable components for the crosslinkable rubber compound with which excellent adhesion properties to the modified cable cores can be achieved using the inventive method. A preferred in this respect is a method according to the invention in which the crosslinkable rubber compound 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, and 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 preferably 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).

[0056] A preferred method according to the invention is wherein the crosslinkable rubberizing 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, in particular precipitated silicon dioxide, and layered silicates, particularly preferably selected from the group consisting of carbon black and amorphous silicon dioxide.

[0057] The aforementioned components of the crosslinkable rubber compound are also possible components of the vulcanizable rubber compound, which can be used as non-metallic reinforcing strips, and are also preferred for these vulcanizable rubber compounds.

[0058] Although it is generally possible to use the modified cable cores produced by the inventive method for any component of the tire, the inventors believe that the most relevant application will usually be in the sidewall area, particularly in the bead area. A preferred method according to the invention for manufacturing a vehicle tire is therefore one in which the tire blank comprises at least two modified cable cores, wherein the modified cable cores are preferably arranged in the sidewall area, wherein the modified cable cores are particularly preferably completely surrounded by a crosslinkable rubber compound, and wherein the modified cable cores are particularly preferably arranged in the bead.

[0059] Although it would be theoretically possible to form the crosslinkable rubber compound surrounding the modified cable core in the tire blank and the vulcanizable rubber compound, preferably used as a non-metallic reinforcing strip, from the same compound, this is less preferred. In this case, the improved adhesion would primarily result from the mechanical wrapping of the cable core, while the compatibility of the vulcanizable rubber compound with the crosslinkable rubber compound would, as expected, be high.

[0060] For many applications, however, it is particularly advantageous to use different compounds. The vulcanizable rubber compound, which forms part of the non-metallic reinforcing strip on the cable core, can be advantageously designed to exhibit maximum adhesion to the cable core, whereas the vulcanizable rubber compound in the vehicle tire blank can be optimized primarily for the physicochemical properties required for use in the vehicle tire. With such a design, a particularly favorable ratio of bond strength to advantageous physicochemical properties of the vehicle tire obtained through vulcanization is regularly achieved.A preferred method according to the invention is therefore for the production of a vehicle tire, wherein the crosslinkable rubber compound surrounding the modified cable core in the tire blank differs from the vulcanizable rubber compound contained in the modified cable core, in particular with regard to the composition of the respective mixture.

[0061] In light of the foregoing, it is evident to those skilled in the art that it is particularly advantageous if no separate adhesion promoter is used, since this would not be required in any case when using the cable core modified in the inventive method. Therefore, a method according to the invention for manufacturing a vehicle tire is preferred, wherein the modified cable core is used in the tire blank without the use of a separate adhesion promoter, in particular without a separate coating with an adhesion promoter.

[0062] The person skilled in the art recognizes that not only is the inventive method for modifying the cable cores advantageous, but that the advantages described above also result for the cable cores produced with this method, i.e., cable cores in whose grooves of the surface non-metallic reinforcing strips are arranged, in particular with regard to the excellent adhesion to rubber materials, which can be achieved even without the use of potentially harmful adhesion promoters.The invention therefore also relates to a modified cable core, preferably manufactured or manufacturable by a method according to the invention, comprising a core filament and at least one filament layer arranged around the core filament, comprising a plurality of outer filaments, wherein the surface of the modified cable core has a plurality of grooves formed by the outer filaments of the outermost filament layer, wherein one or more non-metallic reinforcing strips are arranged in the grooves of the surface of the modified cable core, wherein at least one non-metallic reinforcing strip is selected from the group consisting of coated fibers and rubber strips comprising a vulcanizable rubber compound, wherein the one or more non-metallic reinforcing strips are wound around the outer filament layer of the cable core such that they are arranged in the grooves of the surface of the cable core.

[0063] Since the modified cable cores according to the invention are intended and designed for use in rubber products, and since the advantages of the modified cable core according to the invention are particularly pronounced in this application, it is clear to those skilled in the art that the invention also relates to a corresponding rubber product comprising the cable core and having an advantageously increased bond strength, particularly in the interface between the rubber material and the modified cable core. Accordingly, the invention also relates to a rubber product, in particular an air spring, comprising the modified cable core according to the invention in at least one component, wherein the modified cable core in the rubber product is at least partially surrounded by a cross-linked rubber compound, and wherein a vulcanizable rubber compound optionally contained in the modified cable core is vulcanized.

[0064] A particularly preferred rubber product according to the invention is a vehicle tire, for example for passenger cars or trucks, although it is also suitable for other demanding tire applications, for example in the agricultural or military sector. A preferred rubber product according to the invention is a vehicle tire, preferably a passenger car or truck tire, comprising the modified cable core in the tire bead, preferably as the bead core.

[0065] The invention also relates to a vehicle tire, preferably manufactured or manufacturable using the inventive method for manufacturing a vehicle tire, and / or comprising the inventive modified cable core in at least one component, preferably in the tire bead, particularly preferably as a bead core, wherein the modified cable core in the vehicle tire is at least partially surrounded by a cross-linked rubber compound and wherein a vulcanizable rubber compound optionally contained in the modified cable core is vulcanized. Passenger car and truck tires, as well as tires for agricultural, forestry, and military vehicles, are particularly preferred.

[0066] In light of the foregoing, the surprisingly advantageous use of non-metallic reinforcing strips in the grooves of the surface of a cable core is also part of the invention, since this use surprisingly improves the adhesion of the cable core modified in this way to rubber materials, as disclosed above.Finally, the invention also relates to the use of non-metallic reinforcing strips in the grooves formed on the surface of a cable core by the outer filaments of the outermost filament layer to improve the adhesion of rubber materials to the cable core, wherein at least one non-metallic reinforcing strip is selected from the group consisting of coated fibers and rubber strips comprising a vulcanizable rubber compound, wherein the non-metallic reinforcing strips are wound around the outer filament layer of the cable core in such a way that they are arranged in the grooves of the surface of the cable core.

[0067] Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying drawings. These show: Fig. 1 shows a schematic flow diagram of the inventive method for modifying a cable core in a first preferred embodiment in cross-section through a cable core; Fig. 2 shows a schematic flow diagram of the inventive method for modifying a cable core in a second preferred embodiment in cross-section through a cable core; and Fig. 3 shows a schematic flow diagram of the inventive method for modifying a cable core in a third preferred embodiment in cross-section through a cable core.

[0068] Fig. 1Figure 1 shows a schematic visualization in three steps of the inventive method for modifying a cable core 10 in a first preferred embodiment, wherein the cable core 10 and the non-metallic reinforcing strips 18 are shown in cross-section for clarity. A cable core 10 is provided, comprising a core filament 12 and a filament layer arranged around the core filament 12, wherein the filament layer, which in this case is automatically also the outermost filament layer, is formed by eight outer filaments 14 that uniformly surround the core filament 12.

[0069] The arrangement of the outer filaments 14 results in a total of eight grooves 16 on the surface of the cable core 10. In the illustrated example, the core filament 12 is formed in one piece, and the outer filaments 14 are wound around the core filament 12 (S-twisted). The outer filaments 14 of the outer filament layer touch each other, resulting in a dense filament layer. In the example shown, all of the filaments, i.e., the core filament 12 and the outer filaments 14, are made of steel and coated with a two-layer coating consisting of a first copper layer and an overlying bronze coating.

[0070] In the middle figure, a non-metallic reinforcing strip 18 is now arranged on the provided cable core 10, the arrangement taking place in a groove 16 in the surface of the cable core 10, so that a modified cable core 20 is obtained. This arrangement is carried out after the cable core 10 has been manufactured. In the Fig. 1 In the example shown, the non-metallic reinforcing strip 18 is a nylon yarn coated with carbon black by dip coating. This coated yarn is arranged in the corresponding groove 16 along the entire length of the cable core 10, so that it runs essentially parallel to the outer filaments 14 that form the groove 16. Since the non-metallic reinforcing strip 18 follows the winding, it is also wound around the cable core 10, thus creating an additional mechanical connection.

[0071] In a further process step, additional non-metallic reinforcing strips 18 are now arranged in the further grooves 16 on the surface of the cable core 10, so that in the right-hand figure the in Fig. 1 In the illustrated embodiment, all grooves 16 are covered with corresponding non-metallic reinforcing strips 18. In this embodiment, the materials used for the non-metallic reinforcing strips 18 alternate between the nylon coated as described above and a polyester yarn (PET) coated with an RFL dip, resulting in a particularly high-performance modified cable core 20.

[0072] The in Fig. 2 The schematically represented process flow of the method according to the invention corresponds in its basic structure to that in Fig. 1 The procedure shown. Fig. 2However, a non-metallic reinforcing strip 18 is a rubber strip comprising a vulcanizable rubber compound, which can be obtained, for example, by extrusion. The viscosity of the non-metallic reinforcing strip 18 is selected such that it can be adapted to the shape of the groove 16 by slight pressure, thereby smoothing the overall surface of the cable core 10. Analogously to the Fig. 1 Here too, a corresponding non-metallic reinforcing strip 18 can be arranged in all grooves 16, whereby at the end of the Fig. 2 The method shown results in a modified cable core 20, on whose surface only minor metallic areas are visible.

[0073] The in Fig. 3 The schematically represented process flow of the method of the invention largely corresponds to the one described above. Fig. 2described method. However, in this example, the viscosity of the vulcanizable rubber compound used is higher, so in the last step, a forming tool is used to shape the non-metallic reinforcing strips 18 arranged in the grooves 16 of the surface of the modified cable core 20. The modified cable core 20 is guided through the annular recess of this tool to press the non-metallic reinforcing strips 18 onto the cable core 10 and remove excess material, so that the final cross-section of the modified cable core 20 essentially corresponds to the envelope of the cross-section of the cable core 10, since a formed non-metallic reinforcing strip 18 is arranged in each of the grooves 16. Reference symbol list

[0074] 10 Cable core 12 Core filament 14 Outer filaments 16 Grooves 18 Non-metallic reinforcing strip 20 Modified cable core

Claims

1. Method for modifying a cable core (10), in particular for use in tyre manufacture, comprising the following method steps: v1) producing or providing a cable core (10), comprising a core filament (12) and at least one filament ply arranged around the core filament (12), comprising a multiplicity of outer filaments (14), wherein the surface of the cable core (10) has a multiplicity of grooves (16), which are formed by the outer filaments (14) of the outermost filament ply, v2) producing or providing one or more non-metal reinforcing strips (18), wherein at least one non-metal reinforcing strip (18) is selected from the group consisting of coated fibres and rubber strips, comprising a vulcanizable rubber compound, and v3) arranging the one or more non-metal reinforcing strips (18) in one or more of the grooves (16) of the surface of the cable core (10) to obtain a modified cable core (20), wherein the one or more non-metal reinforcing strips (18) are wound around the outer filament ply of the cable core (10) such that they are arranged in the grooves (16) of the surface of the cable core (10).

2. Method according to Claim 1, wherein the cable core (10) is produced in method step v1), wherein it is produced by winding the outer filaments (14) of the outermost filament ply around the core filament (12) or around the outer filaments (14) of the underlying filament ply, wherein the one or more non-metal reinforcing strips (18) are arranged in the grooves (16) of the surface of the cable core (10) at the same time as the outer filaments (14) of the outermost filament ply are wound.

3. Method according to Claim 1, wherein the one or more non-metal reinforcing strips (18) are arranged in the grooves (16) of the surface of the cable core (10) after the cable core (10) is produced or provided.

4. Method according to one of Claims 1 to 3, wherein at least one non-metal reinforcing strip (18), preferably all of the non-metal reinforcing strips (18), is / are selected from the group consisting of coated glass fibres, natural fibres, synthetic fibres and rubber strips, comprising a vulcanizable rubber compound.

5. Method according to one of Claims 1 to 4, wherein at least one non-metal reinforcing strip (18), preferably all of the non-metal reinforcing strips (18), comprise(s) a vulcanizable rubber compound, wherein the method additionally comprises the following method step: v4) extruding the non-metal reinforcing strips (18) arranged in the grooves (16) of the surface of the modified cable core (20) to adapt the non-metal reinforcing strips (18) to the form of the grooves (16) and / or to create a smoother surface of the modified cable core (20) and / or to at least partially encapsulate, preferably completely encapsulate, the cable core (10) with the vulcanizable rubber compound, wherein the extruding is preferably performed with an extrusion die, wherein the extruding is particularly preferably performed by the modified cable core (20) being passed through an extrusion die with an annular clearance, the inside diameter of which corresponds substantially to the envelope of the cross section of the cable core (10).

6. Method for producing a vehicle tyre, in particular a pneumatic vehicle tyre, comprising the method steps of the method according to one of Claims 1 to 5 and the method steps of: v5) producing a green tyre comprising the modified cable core (20) in at least one component, preferably in the tyre bead, particularly preferably as a bead core, wherein the modified cable core (20) in the green tyre is at least partially surrounded by a crosslinkable rubberizing compound, and v6) vulcanizing the green tyre to produce a vehicle tyre, preferably in a vulcanizing mould.

7. Modified cable core (20), comprising a core filament (12) and, arranged around the core filament (12), at least one filament ply, comprising a multiplicity of outer filaments (14), wherein the surface of the modified cable core (20) has a multiplicity of grooves (16), which are formed by the outer filaments (14) of the outermost filament ply, wherein one or more non-metal reinforcing strips (18) are arranged in the grooves (16) of the surface of the modified cable core (20), wherein at least one non-metal reinforcing strip (18) is selected from the group consisting of coated fibres and rubber strips, comprising a vulcanizable rubber compound, wherein the one or more non-metal reinforcing strips (18) are wound around the outer filament ply of the cable core (10) such that they are arranged in the grooves (16) of the surface of the cable core (10).

8. Rubber product, in particular an air spring, comprising the modified cable core (20) according to Claim 7 in at least one component, wherein the modified cable core (20) in the rubber product is at least partially surrounded by a crosslinked rubberizing compound and wherein a vulcanizable rubber compound possibly contained in the modified cable core (20) is in a vulcanized state.

9. Rubber product according to Claim 8, wherein the rubber product is a vehicle tyre, preferably a car or truck tyre, comprising the modified cable core (20) in the tyre bead, preferably as a bead core.

10. Use of non-metal reinforcing strips (18) in the grooves (16) formed on the surface of a cable core (10) by the outer filaments (14) of the outermost filament ply to improve the adhesion of rubber materials to the cable core (10), wherein at least one non-metal reinforcing strip (18) is selected from the group consisting of coated fibres and rubber strips, comprising a vulcanizable rubber compound, wherein the non-metal reinforcing strips (18) are wound around the outer filament ply of the cable core (10) such that they are arranged in the grooves (16) of the surface of the cable core (10).