Extrusion template and method

Abstract

The invention relates to an extrusion template (10) for use in the extrusion of rubber products, comprising: a) a template body (12), b) a template cut-out (16) which penetrates the template body (12) in an extrusion direction E and is delimited by a circumferential wall surface (14), and c) an elongate injector element (18) which is arranged on the template body (12), the invention relates to an extrusion template (10) comprising a template cutout (16) and a syringe element (18) which extends through the template cutout (16) in the syringe direction I between the wall surfaces (14) with an injection gap (20), the extrusion template (10) being designed to create a material gap in a strand of material extruded through the template cutout (16) in the extrusion direction E by means of the syringe element (18) and to inject an injection composition into the material gap through the injection gap (20), the extrusion die (10) comprises at least one distribution hollow (22) which is wider than the injection gap (20) in the transverse direction Q, and wherein the extrusion die (10) is designed in such a way that the injection composition injected into the material gap can enter the distribution hollow (22), as a result, the extruded strand of material guided via the distribution hollow (22) can be brought into contact with the injection composition on the outside.

Description

Technical Field

[0001] The present invention relates to an extrusion die for use in the extrusion of rubber products, an extrusion system including such an extrusion die, a method for producing a stranded vulcanizable rubber product that can be carried out by extrusion, a method for producing a vulcanized rubber product on the basis of the method, and a vulcanized rubber product produced by such a method. Background Art

[0002] An important component of modern pneumatic vehicle tires is the tread, which in many cases is decisive for the performance characteristics of these products. Today, the tread generally consists of a plurality of different components, especially various rubber materials, which can be obtained by vulcanization from vulcanizable rubber compounds. The corresponding tread is generally produced by co-extrusion of the so-called various vulcanizable rubber compounds and, generally, in terms of their construction, can be suitably described by means of their cross-sections, which are usually uniform throughout the tread strands, apart from the effect of any pattern.

[0003] In cross-sectional view, most treads, especially those in the passenger car and truck industries, include one or more rubber materials that are intended to come into contact with the road during subsequent use and are optimized in terms of their properties for this purpose. Here, the layer that can be said to act as the top layer is produced from a vulcanizable rubber compound, which is sometimes also referred to as a "capping compound" and which generally includes a large proportion of non-conductive fillers, such as precipitated silica.

[0004] Below the rubber material provided for road contact, there is usually a base ply (usually also referred to as the "base"). In the vast majority of cases, this base ply is used in particular to create sufficient adhesion between the top layer provided for road contact and the other parts of the pneumatic vehicle tire, so as to ensure a high-strength bond between the tread and the other components of the pneumatic vehicle tire.

[0005] Those skilled in the art are aware that for most applications, the tread must have a certain overall conductivity, which can prevent unwanted electrostatic accumulation. However, in many cases, the rubber material of the top layer does not have sufficient conductivity to ensure this.

[0006] Thus, in the prior art, the conductivity of the overall tread is generally achieved by means of the base compound of the underlying carcass ply, which has an increased conductivity especially due to the high carbon black content. For this purpose, for example, strands of material are led out of the carcass ply up to the upper side of the tread, thereby establishing an electrical connection between the surface of the tread and the carcass ply. In this case, the conductive base compound is usually formed up to the surface of the tread by a preliminary die in an extruder. Here, the corresponding structure is also referred to as a "carbon center beam" (CCB). Information on the technical background is disclosed, for example, in DE 4445758 B4, DE 69717958 T2, EP 1792720 A2, NL 2006420 C2, and US2018170123 A1.

[0007] However, in many cases, the formation of a CCB from the vulcanizable rubber compound of the underlying carcass ply is considered disadvantageous in terms of production engineering, for example, in terms of the number of required extruder heads, the usually complex flow management in the extruder heads, and the requirements for the material. In addition, the "base" compound is generally not intended for road contact, and thus the resulting partial coverage of the tread surface with the "base" compound is sometimes also considered disadvantageous in terms of driving characteristics. Additionally, some treads completely lack a suitable "base" compound with which a CCB can be realized, and thus the connection between the underside and the surface of the tread must be formed by means of an additional extruder.

[0008] Against this background, there is a need in this technical field for a tread construction that has sufficient conductivity but exhibits the smallest possible influence of the CCB on driving characteristics.

[0009] For this purpose, devices and methods have been developed by means of which, during the production of the tread, particularly thin conductive regions can be produced which, in the subsequent vehicle tire, extend radially through the tread and which are advantageously sufficient to reliably prevent the accumulation of static electricity. These new concepts are based on the fact that, during the formation of the vulcanizable rubber compound, the compound is introduced into the tread by applying the conductive rubber compound in a thin layer thickness to the lateral surface of the extruded strands. To form the lateral surface to be coated, the extruded tread can be cut through in its longitudinal direction, for example, as disclosed in DE 102007039100 A1, or only a part of the tread can be extruded directly and combined with other parts after appropriate coating to give the tread, for example, as disclosed in DE 102007039101 A1. Further disclosures related to such methods can be found, for example, in EP2520421 B1 and EP 3253553 B1. Depending on the requirements of the respective technology employed, the conductive rubber compound can be used directly here as the conductive material for the coating, or a suitable precursor of such a conductive rubber compound can be used directly as a solution or dispersion in an injection composition, particularly a solvent that can evaporate, thus allowing coating from an advantageously flowable solution.

[0010] The inventors have recognized that, in principle, there is a preference for embodiments in which this method is used to form a very thin conductive network (that is, in a case where a thickness of less than 20 μm is established, for example, depending on the viscosity of the conductive rubber compound used). This not only minimizes the influence of the network on the driving characteristics, but also, in particular, enables a reliable connection of the tread parts separated before coating, which, in the estimation of the inventors, is not always sufficiently ensured in the case where the network is significantly thicker. At the same time, the inventors have recognized that the corresponding thickness is sufficient to dissipate static electricity.

[0011] However, if a corresponding thin web is used, the contact area on the lower and upper sides of the tread becomes very small because the corresponding CCB has only a very small cross-sectional area. Here, in the case of the preferred thin web, the reduction is so significant compared to a conventional CCB that there is a risk that the inherently desired degree of reduction in the surface area occupied by the conductive material is too large and in all cases the reliable contact of the underlying surface can no longer be fully ensured. This problem is even further exacerbated by the fact that, for production reasons, there is a risk that during further processing, for example, during the vulcanization process carried out under pressure, the rubber elements of the thin CCB flanks will deform at the boundary surface to such an extent that the intervening thin CCB will be covered by the flank rubber elements, or these flank rubber elements will form a hollow space between them into which the CCB sinks and will thus not reach up to the surface of the tire. In these cases, a actually suitable CCB cannot perform the task it is intended to perform on a new tire because no sufficient conductive path to the road surface is formed. Summary of the Invention

[0012] The main object of the present invention is to eliminate or at least alleviate the drawbacks of the prior art.

[0013] In particular, the object of the present invention is to specify a method for producing a strand-shaped vulcanizable rubber product, in particular a tread, and an apparatus and a system designed for such a method, by means of which a particularly thin web of conductive material can be introduced into the strand-shaped vulcanizable rubber product, which webs, despite their small cross-sectional area, should ensure reliable accessibility and easy electrical contact between the web and the upper and / or lower sides of the strand-shaped vulcanizable rubber product.

[0014] A further object of the present invention is that it should be possible to use the method, apparatus and system to be specified to produce advantageous vulcanizable or vulcanized rubber products, in particular treads with a very thin CCB and thus with excellent rolling characteristics. Thus, the object of the present invention is that, despite the thin CCB, the vulcanizable or vulcanized rubber product should allow reliable dissipation of charge, and in the case of a tread, reliable contact with the road and / or the underlying tire components should be ensured, in particular, especially in the case of a new tire whose tread surface has not been changed by wear.

[0015] Furthermore, the object of the present invention is that the method to be specified should require reduced mechanical expenditure and / or lower requirements on materials compared to the prior art.

[0016] In addition, a supplementary object of the present invention is that the method to be specified should be executable in a manner that is as efficient as possible in terms of time and cost.

[0017] A further object of the present invention is to provide advantageous vulcanized rubber products which can be produced by the processes, devices and systems to be specified.

[0018] The inventors of the present invention have now found that the above object can be achieved if, compared with the processes known from the prior art, not only is a thin conductive modification layer produced in a strand-shaped vulcanizable rubber product using an injection composition, but in addition a surface coating with a conductive material is provided on at least one side, which can be carried out during the extrusion process by means of specific distributed cavities in the extrusion die, as defined in the claims. A thin conductive surface layer which is reliably connected to the thin CCB and ensures a large contact area is advantageously obtained locally in a very efficient manner in terms of time and cost, wherein the rolling characteristics of the tyre are only slightly changed by a relatively small and thin surface modification.

[0019] Accordingly, the above object is achieved by the subject matter of the present invention as defined in the claims. Preferred design embodiments according to the invention follow from the dependent claims and the explanations below.

[0020] In a particularly preferred embodiment, the embodiments hereinafter referred to as preferred are combined with the features of other embodiments referred to as preferred. Accordingly, a combination of two or more of the embodiments hereinafter referred to as particularly preferred is most particularly preferred. Embodiments in which the features of one embodiment referred to as being to some extent preferred are combined with one or more further features of other embodiments referred to as being to some extent preferred are likewise preferred. The features of the preferred extrusion systems, processes and vulcanized rubber products will be apparent from the features of the preferred extrusion die.

[0021] The advantageous vulcanized rubber products of the present invention can be obtained by the process according to the present invention. The process according to the present invention in turn depends on the use of an extrusion system according to the present invention, which is significantly influenced by an extrusion die according to the present invention, which enables process management according to the present invention and thus the obtaining of vulcanized rubber products according to the present invention. Accordingly, the subject matters of the present invention are closely related to one another. For an understandable explanation of the present invention, with regard to the disclosure of the present invention, it is appropriate to start with the extrusion die according to the present invention.

[0022] Accordingly, in a first instance, the present invention relates to an extrusion die for use in the extrusion of rubber products, the extrusion die comprising:

[0023] a) a die body,

[0024] b) a die cutout which penetrates the die body along the extrusion direction E and is delimited by a surrounding wall surface, and

[0025] c) an elongate syringe element extending between the wall surfaces along the syringe direction I through the template incision, having an injection gap,

[0026] wherein the extrusion template is designed to generate a material gap in the material strand extruded through the template incision along the extrusion direction E by means of the syringe element, and to inject an injection composition into the material gap through the injection gap, so that the extruded material strand comes into contact with the injection composition at the walls of the material gap,

[0027] wherein the extrusion template includes at least one distribution cavity in the wall surface of the template incision, wherein the distribution cavity is wider than the injection gap along a transverse direction Q perpendicular to the extrusion direction E and perpendicular to the syringe direction I, and

[0028] wherein the extrusion template is designed such that the injection composition injected into the material gap through the injection gap can enter the distribution cavity, with the result that the extruded material strand guided through the distribution cavity can come into contact with the injection composition present in the distribution cavity on the outside of the material strand guided along the wall surface.

[0029] The extrusion template according to the invention is suitable for use in the extrusion of rubber products. Extrusion templates are well known to those skilled in the art in the field of the rubber processing industry. Extrusion templates are typically subdivided by those skilled in the art into so-called preliminary templates and final templates, which indicates their position in the extrusion system. Preliminary templates typically first guide the rubber strands used into relatively close proximity, and for this reason, these preliminary templates typically include a plurality of incisions, each of which is used to guide a rubber strand. In contrast, final templates typically have only one incision through which the individual rubber strands of the preliminary template pass. The extrusion template according to the invention is particularly suitable for use as a final template, because in this way a conduction network can be formed throughout the strand-shaped rubber product, on the surface of which favorable conduction regions can be formed simultaneously, via which charge dissipation can occur. Thus, for example, there is an extrusion template according to the invention, wherein the extrusion template is a preliminary template, wherein the extrusion template includes two or more, preferably three or more, template incisions penetrating the template body along the extrusion direction E. However, preference is given to the extrusion template according to the invention, wherein the extrusion template is a final template, wherein the extrusion template preferably includes exactly one template incision.

[0030] Due to the specific requirements for the tread of an inflated vehicle tire, the extrusion template according to the invention is particularly suitable for use in the production of these rubber products. Thus, preference is given to the extrusion template according to the invention, wherein the extrusion template is used in the extrusion of the tread of a vehicle tire.

[0031] As is known from the prior art, an extrusion die according to the invention first comprises a die body. This term refers to the workpiece in which the various die openings of the extrusion die are arranged. For example, there is an extrusion die according to the invention in which the die body is formed of metal, preferably steel.

[0032] The die openings in the die body serve to guide the extruded material through the extrusion die. In the context of the present invention, the direction along which the material to be extruded passes through the extrusion die is hereinafter referred to as the extrusion direction E. The shape of the die opening is related to the desired cross-sectional shape of the extruded material strand. In particular, a trapezoidal cross-section has proven to be particularly suitable in this regard for the extrusion of treads. Thus, it is preferred that the extrusion die according to the invention is such that the die opening has a polygonal cross-section, preferably a quadrilateral cross-section, particularly preferably a trapezoidal cross-section, in a plane perpendicular to the extrusion direction E.

[0033] Since the die body will have a non-negligible thickness, the openings penetrating the die body will necessarily be bounded by surrounding wall surfaces. In this regard, a circular die opening will be bounded by, for example, only one surrounding wall surface, while a quadrilateral die opening includes four distinguishable individual wall surfaces as the surrounding walls. In this regard, it is preferred that the extrusion die according to the invention is such that the die opening is bounded by four or more, preferably exactly four, wall surfaces.

[0034] With respect to components a) and b) described above, an extrusion die according to the invention corresponds in principle to an extrusion die known from the prior art. However, an extrusion die according to the invention now further comprises a syringe element having an injection gap, which syringe element extends between the wall surfaces of the die opening, with the result that the syringe element passes through the die opening. In the context of the present invention, the direction along which the syringe element extends from one wall surface to another is referred to as the syringe direction I.

[0035] In an extrusion die according to the invention, the syringe element has mainly two tasks. On the one hand, the syringe element passing through the die opening serves to separate the extruded material strands passing through the die opening by blocking a part of the die opening. Thus, a material gap is formed downstream of the syringe element in the extrusion direction, and this material gap acts as a flow obstacle. The syringe element now serves to inject an injection composition into the material gap through the injection gap facing this material gap. This enables the extruded material strands to come into contact with the injection composition at the walls exposed by the separation. Those skilled in the art will understand that this is thus an extrusion die according to the invention in which the syringe element is configured to be able to inject an injection composition through the injection gap.

[0036] In order to achieve the desired injection function, it is suitable, for example, to connect the syringe element to a source of the injection composition via a pipeline. Thus, an extrusion die according to the invention which is relevant for most cases is an extrusion die in which the syringe element is connected to or can be fluidly connected to a fluid supply unit, where the fluid supply unit preferably comprises a pumping device and a reservoir for storing the injection composition.

[0037] Regarding the arrangement of the syringe element, in the case of a die cutout having a polygonal cross-section, it is particularly preferred that the syringe element extends between opposite parts of the wall. Thus, a preferred extrusion die according to the invention is one in which the syringe element extends from one wall surface of the die cutout to the opposite wall surface.

[0038] Those skilled in the art will understand that the die cutout is divided into two parts by the syringe element, and in the estimation of the inventors, it is thus particularly advantageous, in terms of the properties of the rubber strands that can be produced therefrom, to position the syringe element as centrally as possible, such that the conductive coating introduced through the syringe element extends as centrally as possible in the rubber strands. A preferred extrusion die according to the invention is one in which the syringe element is positioned in the die cutout in such a way that, in a plan view along the extrusion direction E, the die cutout is divided into two partial zones by the syringe element, and the areas of these two partial zones differ by 50% or less, preferably 30% or less, particularly preferably 10% or less, and most preferably 5% or less.

[0039] In order to ensure that the material strands separate around the syringe element in as controlled a manner as possible, and for the extrusion die according to the invention to have a robust structure, the inventors consider it suitable to arrange the syringe element also as centrally as possible relative to the extrusion direction, thereby ensuring that some walls of the extrusion die remain upstream and downstream of the syringe element in the extrusion direction, through which the extruded material can be guided. Thus, a preferred extrusion die according to the invention is one in which the syringe element is positioned in the die cutout in such a way that the distances of the syringe element from the two outlet openings of the die cutout along the extrusion direction E differ by 50% or less, preferably 30% or less, particularly preferably 10% or less, and most preferably 5% or less.

[0040] In principle, the desired separation of the extruded material strands can be achieved by an obstacle of any shape that divides the die cutout into two or more regions, and thus, for example, even syringe elements with a circular cross-section are suitable, which then have a cylindrical shape. However, in the inventors' estimation, it is particularly advantageous if the controlled separation of the material strands is facilitated by providing a wedge shape or a similar taper, which promotes the division along the flanks of the wedge, which in particular improves the flow behavior of the extruded material strands. Thus, by way of example, there is an extrusion die according to the invention, wherein the syringe element preferably has a cylindrical design at least in part over the entire length of the part of the syringe element that extends in the die cutout. However, it is preferred that the extrusion die according to the invention, wherein the syringe element tapers in a direction opposite to the extrusion direction E on the side facing away from the injection gap, preferably in the shape of a droplet.

[0041] At least in theory, the syringe element can be arranged in the extrusion die inclined with respect to the extrusion direction, as a result of which, with respect to the extrusion direction, the extruded material strand comes into contact with the syringe element earlier in one section and later in another section. Even though such a configuration is conceivable, this is not relevant to the advantages that would justify additional design effort in the inventors' estimation. Instead, in the inventors' estimation, particularly good results can be achieved if the syringe element and thus the injection direction I are substantially orthogonal to the extrusion direction, as a result of which the extruded material strand is separated by the syringe element substantially orthogonally to the extrusion direction E. Thus, it is preferred that the extrusion die according to the invention, wherein the syringe direction I encloses an angle in the range from 70° to 110°, preferably in the range from 80° to 100°, particularly preferably in the range from 85° to 95°, very particularly preferably substantially 90°, with the extrusion direction E, and / or wherein the syringe element and the wall surface in the contact area enclose an angle in the range from 70° to 110°, preferably in the range from 80° to 100°, particularly preferably in the range from 85° to 95°, very particularly preferably substantially 90°.

[0042] Depending on the subsequent arrangement of the extrusion die and thus on the gravity acting during use, it is in principle not necessary to form an injection gap over the entire length of the syringe element, since depending on the volume flow rate of the injection composition, the injection composition emerging through the shorter injection gap will be sufficient to fill the material gap and to come into contact with the extruded material strand at the wall over the entire height, which is particularly preferred. However, in view of this preferred embodiment, the inventors consider it particularly advantageous if the injection gap also extends substantially over the entire length where coating is to take place, since thereby a significantly more controlled and precise application of the injection composition into the material gap and its walls becomes possible. Thus, it is preferred that the extrusion die according to the invention is such that the injection gap extends over the entire length of that part of the syringe element which extends in the die incision.

[0043] In the context of the present invention, the mode of operation is generally described with reference to the presence of exactly one syringe element, where an extrusion die according to the invention comprising exactly one syringe element is thus suitable for producing a strand-like rubber product comprising exactly one CCB. However, in this regard, the inventors propose that an extrusion die according to the invention can also be designed in such a way that these extrusion dies can be used to form a plurality of thin CCBs in the extruded material. For certain applications, it is thus preferred that the extrusion die according to the invention is such that the extrusion die comprises two or more, preferably three or more syringe elements of preferably the same type.

[0044] Those skilled in the art will understand that in the method according to the invention carried out using the extrusion die according to the invention, the division of the material strands and the subsequent contact of the injection composition with the walls of the material gap will be followed by the recombination and reconnection of the previously separated parts of the material strands, by means of which the material gap will be closed. In the case of the preliminary die according to the invention, for example, such connection together can be carried out by means of the downstream final die. However, in particular in the case of the final die, if the extruded material extends further along the walls of the die cut in the downstream direction of the injection element in the extrusion direction, the selected length of the die cut in the extrusion direction E can also be so large that the material gap can be connected together while still within the extrusion die according to the invention. In this case, this connection region of the die cut can also include a section with a total cross-section that is at least slightly reduced relative to the die cut at the level of the syringe element, thus ensuring that the two separated parts of the material strands are pressed against each other by means of a corresponding taper. In this case, an extrusion die according to the invention is preferred, wherein the extrusion die comprises a connection region spaced apart from the syringe element along the extrusion direction E, wherein the extrusion die is configured to close the material gap created in the extruded material strands in the connection region by connecting the walls of the material gap that have come into contact with the injection composition, and wherein the connection region is preferably formed by a connection section of the die cut, in which the die cut tapers along the extrusion direction E.

[0045] In this regard, the inventors have proposed suitable dimensions for typical die cuts, which are particularly suitable for the formation of tread components. Here, the dimensions of the die cuts in the extrusion die according to the invention can be suitably defined by means of a predefined direction. The depth of the die cut is determined by the extension along the extrusion direction E. In the context of the present invention, the syringe direction I, which is generally orthogonal to the extrusion direction E, is understood as the height of the die cut. In the context of the present invention, a transverse direction Q, which is orthogonal to the extrusion direction E and the syringe direction I, is also defined. In the particularly preferred case of a non-inclined arrangement of the syringe element in the die cut, these three directions E, I, and Q thus correspond to the axes of a Cartesian coordinate system. It is preferred that the extrusion die according to the invention, wherein the die cut is an elongated die cut and has a diameter in the range of 4 mm to 40 mm, preferably in the range of 5 mm to 30 mm, particularly preferably in the range of 6 mm to 10 mm, along the syringe direction I. Additionally or alternatively, it is preferred that the extrusion die according to the invention, wherein the die cut is an elongated die cut and has a diameter in the range of 5 mm to 500 mm, particularly preferably in the range of 6 mm to 450 mm, very particularly preferably in the range of 8 mm to 400 mm, along the transverse direction Q, wherein the specific dimensions particularly depend on the product to be produced, and thus, the extrusion die for extruding truck treads will have larger dimensions than the extrusion die for bicycle treads. Additionally or alternatively, it is preferred that the extrusion die according to the invention, wherein the die cut has a diameter in the range of 3 mm to 30 mm, particularly preferably in the range of 4 mm to 15 mm, very particularly preferably in the range of 5 mm to 8 mm, along the extrusion direction E.

[0046] Furthermore, the inventors have also proposed suitable dimensions for the syringe element and for the injection gap width, by means of which good results in the formation of a material gap and in the uniform contact of the corresponding walls can be achieved when processing typical vulcanizable rubber compounds and injecting a wide range of injection compositions. It is preferred that the extrusion die according to the invention, wherein the syringe element has an average diameter in the range of 3 mm to 40 mm, particularly preferably in the range of 4 mm to 20 mm, very particularly preferably in the range of 6 mm to 10 mm, along the transverse direction Q. Additionally or alternatively, it is preferred that the extrusion die according to the invention, wherein the syringe gap has an average diameter in the range of 0.1 mm to 2.0 mm, particularly preferably in the range of 0.2 mm to 1.0 mm, very particularly preferably in the range of 0.5 mm to 0.8 mm, along the transverse direction Q.

[0047] Particularly advantageous properties of the extrusion die according to the invention are obtained in particular by using one or more special incisions in the wall surfaces of the die incisions, which one or more special incisions are referred to as distribution hollows in the context of the present invention because they are used to receive the injection composition injected into the material gap from the syringe element and enable the injection composition accumulated in the distribution hollows to come into contact with the material strands forced out via this distribution hollow from the outside, as a result of which the injection composition can be said to be distributed.

[0048] Due to the presence of these distribution hollows, the injection composition comes into contact not only with the walls that will subsequently be joined together again, but also with a part of the surface area that will subsequently form the surface of the extruded material strand, wherein the fluid connection between the material gap and the distribution hollows ensures that in the extruded material strand, the coated surface area and the thin conductive network that can be formed almost simultaneously are reliably connected to each other.

[0049] In this regard, those skilled in the art will understand that the syringe element will project a flow shadow in the extrusion direction E, and thus the material gap will have a certain volume. Therefore, it will not be appropriate to make the distribution hollow so small that it is entirely within the area of the material gap itself, because in this case, the distribution hollow cannot be traversed by the separated parts of the material strand. Therefore, the distribution hollow is also at least wider than the injection gap in the transverse direction Q. In subsequent practice, the actual width of the distribution hollow in the transverse direction will mainly depend on the properties of the vulcanizable rubber compound being processed, the extrusion rate and the geometric configuration of the syringe element acting as a flow obstacle, because in particular, these factors determine the size of the formed material gap. For the extrusion process desired by those skilled in the art, the distribution hollow should therefore have a larger area in the plane orthogonal to the syringe direction I than the cross-section of the formed material gap, wherein the actual size is also determined by the expected width of the surface modification that those skilled in the art want to achieve by means of the distribution hollow.

[0050] For a specified extrusion machine system using a particular vulcanizable rubber compound, in view of the present invention, it is an easy matter for those skilled in the art to identify the appropriate size of the distribution hollow and, if necessary, optimize it in conventional experiments. The complex dependence of the configuration of the extrusion die according to the invention on the subsequent intended application is taken into account in the context of the present invention by the fact that the extrusion die as defined above is configured such that the syringe composition injected into the material gap can penetrate into the distribution hollow in order to come into contact there with the extruded material strand guided via the distribution hollow.

[0051] Basically preferred is an extrusion die according to the invention, wherein the width of the distribution hollow in the transverse direction to the extrusion direction E and in the transverse direction to the syringe direction I is 2 times or more, preferably 5 times or more, particularly preferably 10 times or more, very particularly preferably 20 times or more of the injection gap. Additionally or alternatively, also preferred is an extrusion die according to the invention, wherein the width of the distribution hollow in the transverse direction to the extrusion direction E and in the transverse direction to the syringe direction I is 1.25 times or more, preferably 1.5 times or more, particularly preferably 2 times or more, very particularly preferably 5 times or more of the syringe element. Additionally or alternatively, furthermore preferred is an extrusion die according to the invention, wherein the distribution hollow preferably has an average diameter in the range of 0.1 mm to 2 mm, particularly preferably in the range of 0.2 mm to 1.0 mm, very particularly preferably in the range of 0.3 mm to 0.7 mm along the transverse direction Q.

[0052] The extrusion die according to the invention comprises at least one distribution hollow. Those skilled in the art will understand that a corresponding surface coating can thus be formed on one side of the syringe element and thus on one side of the CCB generated in the material strand, as described above. In the inventors' estimation, this is sufficient for some applications, for example, for ensuring good road contact of the CCB in the case of a tread. However, at the same time, the inventors consider it preferable for substantially all embodiments to provide two distribution hollows in order to form corresponding modified regions on both sides of the surface of the extruded strand. Even though theoretically the above function of a separate distribution opening can be achieved by combining, for example, two separate distribution openings extending to the left and right of the syringe element, it is not difficult for those skilled in the art to understand that these two distribution hollows should preferably be arranged in the walls at opposite ends of the syringe element, thus ensuring that the material strand extruded through the extrusion die is provided with an associated surface coating on both sides of the thin conductive web, so that in the case of a tread, not only excellent road contact can be ensured, but also a reliable connection with, for example, the underlying carcass ply of the tread can be ensured. Therefore, in the case of substantially all embodiments, also preferred is an extrusion die according to the invention, wherein the extrusion die includes at least one distribution hollow of preferably the same type in the region in each of the opposite wall surfaces of the die cut that contacts the syringe element, wherein the extrusion die is configured such that the injection composition injected into the material gap through the injection gap can enter the distribution hollow, so that the extruded material strand guided by the distribution hollow can come into contact with the injection composition present in the distribution hollow at the outside of the material strand guided along the wall surface.

[0053] Even if the distributed hollow portions can be arranged by more complex fluid guidance in such a way that these distributed hollow portions extend at least partially upstream of the syringe element relative to the extrusion direction E, in the estimation of the inventors, it is advisable that the resulting CCB makes contact as reliably as possible with the conductive surface coating in order to provide the distributed hollow portions and the injection gap on the same side of the syringe element. Therefore, it is preferred to use an extrusion template according to the invention, wherein the distributed hollow portions are arranged in the wall surface of the template incision on the side of the syringe element that includes the injection gap.

[0054] At least theoretically, it is conceivable that the distributed hollow portions are spaced apart from the syringe element by at least a certain amount along the extrusion direction E. However, in the estimation of the inventors, in the case of substantially all embodiments, it is preferred that the distributed hollow portions are directly adjacent to the syringe element in the extrusion direction E, and in particular, embodiments in which a part of the side wall of the distributed hollow portion is formed by a part of the syringe element are also preferred. It is preferred to use an extrusion template according to the invention, wherein a part of the side wall of the distributed hollow portion is formed by the syringe element.

[0055] During the design of the extrusion template according to the invention, it has been found that it is not a problem if the distributed hollow portions exhibit sharp edges at the upstream ends in the extrusion direction, since the extruded material compound usually slides over this edge without problems. However, depending on the configuration of the material used and depending on the size of the distributed hollow portions, the material strands can partially sink into the distributed hollow portions as they slide over them. If then a very sharp edge is also provided on the downstream side, for example as obtained by a completely square hollow portion, this edge of the distributed hollow portion may impede the sunken part of the material strands and may lead to undesired changes or impairments of the material and flow behavior. To avoid this, the inventors propose that the side of the distributed hollow portion facing the extrusion direction E should protrude in as flat a manner as possible in order to guide any part of the material strands that have sunk into the distributed hollow portion back onto the original extrusion path without too much resistance. Therefore, it is preferred to use an extrusion template according to the invention, wherein the depth of the distributed hollow portion decreases along the extrusion direction E as the distance from the syringe element increases. Additionally or alternatively, it is also preferred to use an extrusion template according to the invention, wherein the distributed hollow portion tapers away from the syringe element along the extrusion direction E. Additionally or alternatively, it is preferred here to use an extrusion template according to the invention, wherein the distributed hollow portion has a triangular or trapezoidal cross-section, preferably a triangular cross-section, in a plane parallel to the extrusion direction E.

[0056] As a particularly preferred embodiment of the extrusion die according to the invention, the inventors propose that the syringe element can have a replaceable design. For this purpose, complementary openings or incisions can be provided on opposite sides of the wall into which the syringe element can be inserted. In this case, the syringe insertion opening can be implemented, for example, as a drill hole through the die body, thus enabling the syringe element to pass through the drill hole into the die incision until the syringe element is arranged in the syringe receiving incision on the opposite side and is fixed there, for example, by form-locking engagement. Thereby, for example, with respect to the shape of the syringe element and / or the configuration of the corresponding injection gap, the selection of the syringe element can be advantageously matched to the material to be processed. Therefore, it is preferred that the extrusion die according to the invention, wherein the extrusion die includes a syringe receiving incision and a syringe insertion opening in the wall surface of the die incision, wherein the syringe element extends through the syringe insertion opening into the syringe receiving incision, wherein the extrusion die is designed such that the syringe element can be replaced in a reversible and non-destructive manner, and wherein one or more distribution cavities are preferably formed by a part of the syringe insertion opening and / or the syringe receiving incision.

[0057] In a further development of syringe elements that can be replaced in a reversible and non-destructive manner, the inventors propose that it is additionally possible to provide a plurality of complementary insertion openings and receiving incisions, such that the extrusion template according to the invention can use the syringe elements in various syringe positions, for example to achieve a higher flexibility with respect to the positioning of the CCB in the tread, without having to manufacture new extrusion templates, thus for example enabling the position of the CCB to be adapted to the desired pattern. In such an embodiment, in the estimation of the inventors, it is expedient to close unused syringe insertion openings or syringe receiving incisions with suitable closing elements (for example, with form-fitting rubber plugs). Accordingly, preference is given to an extrusion template according to the invention, wherein the extrusion template comprises two or more, preferably three or more, particularly preferably four or more complementary syringe insertion openings and syringe receiving incisions for receiving syringe elements in different syringe positions in the wall surface of the template incision, wherein at least some, preferably all, of the syringe positions are assigned at least one, preferably at least two, opposing distribution cavities, wherein in one syringe position, the syringe element extends through the corresponding syringe insertion opening into the corresponding syringe receiving incision, and wherein the extrusion template is designed such that the position of the syringe element can be changed between syringe positions in a reversible and non-destructive manner. Particularly preferred here is an extrusion template according to the invention, wherein additionally the extrusion template comprises one or more closing elements for closing, preferably form-fittingly closing, the syringe insertion openings and syringe receiving incisions of syringe positions not occupied by syringe elements and / or the distribution cavities assigned to these syringe positions.

[0058] The invention further relates to an extrusion system comprising:

[0059] aa) at least one extruder, and

[0060] bb) at least one extrusion template according to the invention.

[0061] In this case, the extrusion die according to the invention can be combined essentially with all suitable typical extruders, which can be commercially obtained from various sources. Here, the positioning of the extrusion die according to the invention in the extrusion system will depend in particular on whether it is an initial die or a final die embodiment. For example, there is an extrusion system according to the invention, in which the extrusion system additionally includes an additional initial die arranged between the extrusion die and the extruder, or includes an additional final die arranged on the side facing away from the extruder, wherein the additional initial die and the additional final die preferably do not include syringe elements. As an alternative or additionally, another illustrative extrusion system according to the invention is an extrusion system in which the extrusion system additionally includes a connecting element arranged on the side facing away from the extruder and having a connecting area, wherein the extrusion system is configured to close the material gap generated in the extruded material strand by connecting the walls of the material gap that have come into contact with the injection composition in the connecting area, wherein the connecting element is preferably formed by an additional final die arranged on the side facing away from the extruder.

[0062] Furthermore, the invention relates to a method for producing a strand-shaped vulcanizable rubber product using an extrusion system according to the invention, the method comprising the following method steps:

[0063] i) Extruding a material strand composed of at least one vulcanizable rubber compound through an extrusion die according to the invention along an extrusion direction E by means of an extruder, wherein a material gap is generated in the material strand by means of a syringe element,

[0064] ii) Injecting an injection composition from an injection gap into the material gap and the distribution hollow part so that the material strand comes into contact with the injection composition at the walls of the material gap and on the outer side of the material strand guided along the wall surface in order to obtain a modified material strand,

[0065] iii) Closing the material gap in the modified material strand by connecting the walls of the material gap that have come into contact with the injection composition in a connecting area, which is spaced apart from the syringe element along the extrusion direction E.

[0066] The method according to the invention is used for producing a strand-shaped vulcanizable rubber product, preferably a tread component. However, the method according to the invention is not limited to the tread, but is essentially applicable to adding a conductive structure to any thick-walled extrudate having a certain thickness (for example, greater than 2 mm), by means of which the static charge can be reliably dissipated. Thus, for example, there is a method according to the invention, in which the strand-shaped vulcanizable rubber product has an average thickness of 2 mm or more perpendicular to the extrusion direction E. Preferably, in the method according to the invention, the strand-shaped vulcanizable rubber product is a tread blank or a ply of a tread blank.

[0067] It can be considered that the main advantage of the method according to the present invention is that it is very flexible with respect to the vulcanizable rubber compounds used. Given that the advantageous effects of the present invention are basically attributed to the design features of the extrusion die according to the present invention and the specific process management, it can be advantageously observed that the method according to the present invention can be used for substantially all typical vulcanizable rubber compounds, especially those used in the treads of vehicle tires, and thus, in this regard, reference can be made in particular to the prior art known to those skilled in the art. In this regard, for example, there is a method according to the present invention, wherein the vulcanizable rubber compound comprises one or more diene rubbers, and / or wherein the vulcanizable rubber compound comprises one or more non-conductive fillers, and / or wherein the vulcanizable rubber compound comprises one or more additives selected from the group consisting of plasticizers, anti-aging agents and coupling agents.

[0068] Since the method according to the present invention is highly relevant for providing extrudates with a low conductivity of the conductive CCB, in most cases this will be a method according to the present invention, wherein the vulcanizable rubber compound comprises less than 10 phr, preferably less than 5 phr, particularly preferably less than 3 phr, and especially less than 0.1 phr of carbon black.

[0069] In view of the above statements, those skilled in the art will understand that the extrusion die according to the present invention and the method according to the present invention are not restricted in principle with respect to the injection compositions used either. Those skilled in the art will basically select suitable injection compositions in view of their respective application requirements, the vulcanizable rubber compounds used, the extrusion materials, and other parameters of their specific process management, so as to ensure that these injection compositions are suitable for their purposes. Examples of injection compositions that can be used are disclosed in particular in the prior art recognized above. In this regard, for example, there is a method according to the present invention, wherein the injection composition is a dispersion comprising:

[0070] - at least one diene rubber, preferably polyisoprene,

[0071] - at least one conductive filler, preferably carbon black, preferably having a combined mass content of 50 phr or more, preferably 70 phr or more, and

[0072] - a carrier liquid, preferably having a combined mass content of 450 phr or more, preferably 600 phr or more.

[0073] In this regard, furthermore, for example, there is a method according to the present invention, wherein the injection composition further comprises:

[0074] - At least one liquid diene polymer, preferably having a combined mass content of 50 phr or more, preferably 70 phr or more, and / or

[0075] - A sulfur-based vulcanization system, preferably comprising at least one vulcanization accelerator, particularly preferably having a combined mass content of 2.5 phr or more, preferably 5 phr or more.

[0076] The term phr (parts per hundred parts of rubber by weight) used herein is a conventional quantity index in the rubber industry for compound formulations, by means of which the mass content of components in a rubber compound is indicated relative to the mass of the high molecular weight rubber present in the rubber compound (weight average molar mass Mw according to GPC greater than 60 000 g / mol), where the combined mass content of the high molecular weight rubber in the rubber compound corresponds to 100 phr. The determination of the weight average molar mass is carried out by gel permeation chromatography according to DIN 55672-1:2016-03 (GPC, using tetrahydrofuran as the eluent, polystyrene standard; SEC = size exclusion chromatography).

[0077] For the selection of the injection composition, the inventors propose that in the method according to the invention, injection compositions with not too high viscosities can be processed particularly efficiently, so that they can flow out of the material gap into the distribution cavity in a particularly efficient manner and come into contact with the wall there. Therefore, the method according to the invention is preferred, wherein the dynamic viscosity η of the injection composition measured at 20 °C according to DIN 53211:1987-06 is 30 Pa*s or less, preferably 20 Pa*s or less, particularly preferably 10 Pa*s or less.

[0078] Injectable compositions known from the prior art generally rely on the use of volatile solvents as carrier liquids. Thereby, the components of the rubber composition dispersed in the solvent contained in the injectable composition can be applied to the walls of the material gaps, and after the solvent has evaporated, these components remain there as a coating. However, the inventors of the present invention have found that for process engineering and health reasons, and in view of the quality of the resulting conductive network, it is highly preferred to avoid using volatile solvents as much as possible. Instead, the inventors have developed a technique in which the carrier liquid is formed by high-boiling components (i.e., especially mineral oils, and in this case especially paraffin mineral oils). The corresponding injectable composition is not (at least not primarily) converted into a coating by evaporation of the solvent; rather, a large proportion of the mineral oil can penetrate into the underlying vulcanizable rubber compound, leaving a coating that generates a surface layer due to contact with the injectable composition, which surface layer particularly has an increased carbon black content and thus has a favorable electrical conductivity. Therefore, it is particularly preferred that in the method according to the present invention, the carrier liquid is a mineral oil, preferably a paraffin mineral oil. Additionally or alternatively, it is also particularly preferred that in the method according to the present invention, the carrier liquid has a boiling point of 120 °C or higher, preferably 140 °C or higher, particularly preferably 160 °C or higher.

[0079] Furthermore, the present invention relates to a method for producing a vulcanized rubber product, which method comprises the method steps of the method according to the present invention for producing a strand-shaped vulcanizable rubber product, and the following steps:

[0080] iv) vulcanizing the strand-shaped vulcanizable rubber product or a rubber blank comprising the strand-shaped vulcanizable rubber product, preferably a vehicle tire blank, wherein the vulcanizable rubber compound is vulcanized to obtain a vulcanized rubber product, preferably a vehicle tire.

[0081] Here, the strand-shaped vulcanizable rubber product is vulcanized, for example, by methods customary in the tire industry (e.g., by sulfur-based crosslinking, e.g., at a temperature in the range of 130 °C to 200 °C, preferably in the range of 150 °C to 180 °C).

[0082] Finally, the present invention also relates to a vulcanized rubber product, which vulcanized rubber product is preferably produced by or can be produced by the method according to the present invention for producing a vulcanized rubber product, wherein the rubber element comprises a vulcanized rubber compound,

[0083] wherein, on at least one surface, the rubber element comprises a modified region extending on the surface along the covering direction B,

[0084] wherein the rubber element comprises a modified layer that is connected to the modified region along the covering direction B and extends through the rubber element along the layer direction S,

[0085] Among them, the modified region and the modified layer include a vulcanized rubber material, and the composition of this vulcanized rubber material is different from the composition of the vulcanized rubber compound.

[0086] Among them, the average width of the modified layer in the extension direction A is 30 μm or less, and this extension direction is perpendicular to the covering direction B and perpendicular to the layer direction S.

[0087] Among them, the average width of the modified layer in the extension direction A is smaller than the average width of the modified region, and this extension direction is perpendicular to the covering direction B and perpendicular to the layer direction S.

[0088] In principle, the vulcanized rubber product can be any form of rubber product, which includes the extrusion of a stranded starting material in a previous working step. The vulcanized rubber product according to the present invention is vulcanized and therefore no longer includes any vulcanizable rubber compound, but includes the corresponding rubber material that can be produced from it. Therefore, the vulcanized rubber product particularly includes a rubber element, and this rubber element includes a specific conductive structure that can be produced by the method according to the present invention. For example, the corresponding rubber element can be the tread of an inflated vehicle tire.

[0089] Preferred is the vulcanized rubber product according to the present invention, wherein this vulcanized rubber product is a vehicle tire, preferably an inflated vehicle tire. In this context, preferred is the vulcanized rubber product according to the present invention, wherein the rubber element is a tread or a constituent ply of the tread, particularly a constituent ply of the tread intended for road contact.

[0090] In the context of the present invention, the assembly of the conductive structure from the web (i.e., the modified layer) and the conductive surface layer (i.e., the modified region) in the rubber element is mainly defined with respect to two directions (i.e., the covering direction B and the layer direction S).

[0091] On at least one surface, the rubber element includes a modified region, in which the composition is different from the composition of the remaining vulcanized rubber compound in the rubber element, and as explained above, this can be achieved by coating or modifying the previous vulcanizable rubber compound in the method according to the present invention. Those skilled in the art will understand that the modified region is only the part that has been produced in the extruded stranded vulcanizable rubber product by the action of the distribution hollow in the extrusion template according to the present invention. Therefore, at the production time point of the unvulcanized rubber element, the covering direction B corresponds to the extrusion direction E.

[0092] By means of the above process management, the modified region is connected to the modified layer (i.e., the thin conductive CCB). This modified layer extends through the vulcanized rubber product and is materially connected to the surface modified region. Due to contact with the injection composition, the modified layer also has a chemical composition different from the surrounding vulcanized rubber compound.

[0093] The direction in which the modified layer extends through the rubber element is referred to as the layer direction S. Using as an example a tread of an inflated vehicle tire that includes a conductive structure approximately centered relative to the tread, the covering direction B thus corresponds to the circumferential direction, while the layer direction S approximately corresponds, for example, to the radial direction.

[0094] Furthermore, the above definitions of the vulcanized rubber product according to the invention represent the dimensions that the modified layer and the modified region have relative to each other. In a direction perpendicular to the covering direction B and perpendicular to the layer direction S, these relationships will be defined as the extension direction A. In a preferred embodiment where the modified layer and the modified region are substantially orthogonally oriented, this third direction corresponds to the third axis of a Cartesian coordinate system. Using as an example a tread located on a vehicle tire, the covering direction of the tread is the circumferential direction and the layer direction of the tread is the radial direction, the extension direction A will correspond to the axial direction.

[0095] The preferred vulcanized rubber product according to the invention will be clear from the statements above regarding the preferred method and the extrusion die.

[0096] For example, it is preferred that the vulcanized rubber product according to the invention, wherein on each of two opposite surfaces, preferably on the surface provided for road contact and the surface facing away from said surface, the rubber element includes a modified region extending along the covering direction B on this surface, wherein the modified layer is connected to the two modified regions.

[0097] Furthermore, it is preferred that the vulcanized rubber product according to the invention, wherein the modified layer extends completely through the rubber element along the layer direction S.

[0098] It is also preferred that the vulcanized rubber product according to the invention, wherein the rubber element includes two or more tread plies made of different vulcanized rubber compounds, wherein the modified layer extends through all the tread plies along the layer direction S.

[0099] It is likewise preferred that the vulcanized rubber product according to the invention, wherein the rubber element is arranged in the vulcanized rubber product with one surface on the conductive ply, wherein the modified layer extends from the surface provided for road contact to the conductive ply along the layer direction S, and wherein the modified region preferably contacts the conductive ply.

[0100] It is likewise preferred that the vulcanized rubber product according to the invention, wherein the average width of the modified layer in the extension direction A is 20 μm or less, preferably 10 μm or less, particularly preferably 5 μm or less, and / or wherein the average width of the modified layer in the extension direction A is in the range of 0.5 μm to 20 μm, preferably in the range of 1 μm to 10 μm.

[0101] Furthermore, it is preferred that the vulcanized rubber product according to the present invention, wherein the average width of the modified region in the extension direction A is 50 mm or less, preferably 10 mm or less, particularly preferably 5 mm or less, and / or wherein the average width of the modified region in the extension direction A is in the range of 1 mm to 40 mm, preferably in the range of 2 mm to 20 mm, particularly preferably in the range of 3 mm to 10 mm.

[0102] Furthermore, it is preferred that the vulcanized rubber product according to the present invention, wherein the average width of the modified layer in the extension direction A is 20 times or more, preferably 50 times or more, particularly preferably 100 times or more, very particularly preferably 200 times or more of the modified layer.

[0103] It is also preferred that the vulcanized rubber product according to the present invention, wherein the vulcanized rubber material has a higher electrical conductivity than the vulcanized rubber compound, preferably 10 times or more, preferably 100 times or more, particularly preferably 1000 times or more.

[0104] Furthermore, it is preferred that the vulcanized rubber product according to the present invention, wherein the vulcanized rubber compound can be produced by vulcanizing a vulcanizable rubber compound, and wherein the vulcanized rubber material can be produced by vulcanizing an injection composition, the injection composition comprising:

[0105] - at least one diene rubber, preferably polyisoprene,

[0106] - at least one conductive filler, preferably carbon black, preferably having a combined mass content of 50 phr or more, preferably 70 phr or more, and

[0107] - a carrier liquid, preferably having a combined mass content of 450 phr or more, preferably 600 phr or more,

[0108] Or a mixed composition comprising a vulcanizable rubber compound and an injection composition, the mixed composition can be produced by bringing the injection composition into contact with the vulcanizable rubber compound. BRIEF DESCRIPTION OF THE DRAWINGS

[0109] The present invention and preferred embodiments of the present invention will be explained and described in more detail hereinafter with reference to the drawings. In the drawings:

[0110] Figure 1 A highly simplified schematic illustration of material defects occurring in the prior art is shown;

[0111] Figure 2 A schematic illustration of an extrusion die according to the present invention in a preferred embodiment is shown;

[0112] Figure 3 Shows Figure 2Enlarged view of the area around the syringe element of the extrusion template according to the invention, as shown;

[0113] Figure 4 Schematic exploded view of a vulcanized rubber product according to the invention in a preferred embodiment; and

[0114] Figure 5 Shows Figure 4 Schematic visualization of the conduction structure of the vulcanized rubber product shown.

[0115] List of reference numerals

[0116] 10 Extrusion template

[0117] 12 Template body

[0118] 14 Wall surface

[0119] 16 Template cutout

[0120] 18 Syringe element

[0121] 20 Injection gap

[0122] 22 Distribution hollow part

[0123] 24 Vulcanized rubber product

[0124] 26a, 26b Modified area

[0125] 28 Modified layer

[0126] E Extrusion direction

[0127] I Syringe direction

[0128] Q Transverse direction

[0129] B Covering direction

[0130] S Layer direction

[0131] A Extension direction Detailed description

[0132] Figure 1 Visualizes, in a highly simplified illustration, the defects that can occur in the extruded material strands when the conduction network is made particularly thin. In Figure 1 a) of, the conduction network is overlapped by the material strands on its flanks after extrusion and does not extend far enough to the intended contact surfaces of the corresponding rubber product. In Figure 1 b) of, the ends of the conduction network are covered by material displacements of the type that can occur, for example, after the tread blank has been inserted into the tire mold. In Figure 1 both cases, the conduction network cannot ensure the required charge dissipation.

[0133] Figure 2 shows the extrusion die 10 (sometimes also referred to as the injection rod) according to the invention in a preferred embodiment. In this case, the extrusion direction E, the syringe direction I, and the transverse direction Q have been entered in Figure 2 .

[0134] The extrusion die 10 according to the invention comprises a die body 12 and a die cutout 16 enclosed by wall surfaces 14 in this die body 12. A syringe element 18 extends through the die cutout 16 between the wall surfaces 14 and comprises an injection gap 20.

[0135] In Figure 2 the example shown, the extrusion die 10 is implemented as a preliminary die and has a die body 12 made of steel, in which there is a die cutout 16 with a trapezoidal cross-section. The syringe element 18 extends through the die cutout 16 between the wall surfaces 14 and is arranged exactly centered in the example shown.

[0136] At the end of the syringe element 18 outside the extrusion die 10, a drilling is indicated, via which the syringe element 18 can be connected via a fluid line to a reservoir (not shown) for injecting the composition. In this case, the cylindrical syringe element 18 is substantially orthogonal to the wall surfaces 14, wherein the injection gap 20 extends substantially over the entire height of the die cutout 16. In the wall surfaces 14 of the die cutout 16, in each case in the region in contact with the syringe element 18, the extrusion die 10 has two identically designed distribution cavities 22 (only one visible), which are arranged such that the injection composition from the injection gap 20 can also enter the distribution cavities 22 during operation, so that the injection composition can also come into contact with the extruded material strands passing through it from the outside along the wall.

[0137] Figure 2 The syringe element 18 in

[0138] Figure 3 shows Figure 2 an enlarged detail of the extrusion die 10 according to the invention as shown, in which, in particular, the details in the region of the syringe element 18 are shown to an enlarged scale. One of the two distributed cavities 22 is particularly clearly visible in Figure 3 . In the transverse direction Q, the distributed cavity 22 is wider than the injection gap 20, where Figure 3 the relationships that are particularly relevant in practice are not shown in the schematic illustration. In practice, for the sake of clarity, the injection gap 20 will in most cases likely be significantly smaller than Figure 3 that indicated in Figure 3 . For example, the injection gap 20 can have an average width of about 0.1 mm, while the distributed cavity 22 has a width of, for example, 3 mm in the transverse direction Q in order to advantageously form a wide contact surface in the rubber product that can be produced therewith. As can be seen in

[0139] Then, Figure 4 a schematic illustration of a vulcanized rubber product 24 of the type that can be obtained with the extrusion die 10 as shown in Figure 2 and Figure 3 is shown in an exploded view, where, for the sake of clarity, only one segment of the strand is depicted, and this segment can also extend significantly longer in the covering direction B. The schematically shown vulcanized rubber product 24 is a tread having a "cap" and "base" configuration.

[0140] The tread portions arranged on both sides and consisting of a vulcanized rubber compound are separated from each other by a conductive structure that can be produced by the method according to the invention using the extrusion die 10 according to the invention, where the selected exploded view is used to make this structure more visible. Figure 4 Details of the tread are shown, in which the covering direction B has been entered, and the modified regions 26a, 26b extend along this covering direction on the surface of the vulcanized rubber product 24. The layer direction S has also been entered, and the modified layer 28 extends along this layer direction through the "cap" and "base" plies of the vulcanized rubber product 24. The extension direction A (along which the widths of the modified layer 28 and the two modified regions 26a, 26b can be determined) is perpendicular to these two directions in each case. For the modified layer 28, the vulcanized rubber product 24 advantageously includes a thin CCB, however, for this CCB, advantageous contact is possible through the large but on the other hand thin modified regions 26a, 26b compared with the prior art.

[0141] Finally, Figure 5shows Figure 4 a schematic enlarged view of the conductive structure in Figure 4 . Here, it can be clearly seen that these two modified regions 26a, 26b have a significantly greater average width along the extension direction A than the modified layer 28. However, at the same time, it can also be seen that the thickness of the modified regions 26a, 26b along the layer direction does not differ significantly from the thickness of the modified layer 28.

Claims

1. An extrusion die (10) for use in the extrusion of rubber products, the extrusion die comprising: a) a die body (12), b) a die cut (16) that penetrates the die body (12) along an extrusion direction E and is bounded by surrounding wall surfaces (14), and c) an elongate syringe element (18) that extends between the wall surfaces (14) through the die cut (16) along a syringe direction I, the syringe element having an injection gap (20), wherein the extrusion die (10) is designed to create a material gap in a material strand extruded through the die cuts (16) along the extrusion direction E by means of the syringe element (18), and to inject an injection composition through the injection gap (20) into the material gap so that the extruded material strand contacts the injection composition at the walls of the material gap, wherein the extrusion die (10) includes at least one distribution cavity (22) in the wall surface (14) of the die cut (16), wherein the distribution cavity (22) is wider than the injection gap (20) along a transverse direction Q that is perpendicular to the extrusion direction E and perpendicular to the syringe direction I, and wherein the extrusion die (10) is designed such that the injection composition injected through the injection gap (20) into the material gap can enter the distribution cavity (22), with the result that the extruded material strand guided through the distribution cavity (22) can contact the injection composition present in the distribution cavity (22) outside the material strand guided along the wall surface (14).

2. The extrusion die plate (10) according to claim 1, wherein, The width of the distribution cavity (22) transverse to the extrusion direction E and transverse to the syringe direction I is 5 times or more that of the injection gap (20).

3. The extrusion die plate (10) according to any one of claims 1 or 2, wherein The depth of the distribution cavity (22) decreases along the extrusion direction E as the distance from the syringe element (18) increases.

4. The extrusion die plate (10) according to any one of claims 1 to 3, wherein, The side walls of the distribution cavity (22) are partly formed by the syringe element (18).

5. The extrusion die plate (10) according to any one of claims 1 to 4, wherein, The extrusion die (10) includes at least one distribution cavity (22) in the region of each of the opposite wall surfaces (14) of the die cut (16) that contacts the syringe element (18).

6. The extrusion die plate (10) according to any one of claims 1 to 5, wherein, The extrusion die (10) includes a syringe receiving cut and a syringe insertion opening in the wall surfaces (14) of the die cut (16), wherein the syringe element (18) extends through the syringe insertion opening into the syringe receiving cut, and wherein the extrusion die (10) is designed such that the syringe element (18) can be replaced in a reversible and non-destructive manner.

7. The extrusion die plate (10) according to any one of claims 1 to 6, wherein, The extrusion die (10) includes two or more complementary syringe insertion openings and syringe receiving cuts in these wall surfaces (14) of the die cutout (16) for receiving syringe elements (18) in different syringe positions, wherein at least some of these syringe positions are assigned at least one distribution hollow (22), and wherein in one syringe position, the syringe element (18) extends through the corresponding syringe insertion opening into the corresponding syringe receiving cut, and wherein the extrusion die (10) is designed such that the position of the syringe element (18) can be changed between these syringe positions in a reversible and non-destructive manner.

8. An extrusion system, comprising: aa) at least one extruder, and bb) at least one extrusion die (10) as claimed in any one of claims 1 to 7.

9. A method for producing a strand-shaped vulcanizable rubber product using the extrusion system as claimed in claim 8, the method comprising the following method steps: i) Extruding a strand of material composed of at least one vulcanizable rubber compound through the extrusion die (10) along the extrusion direction E by means of an extruder, wherein, generating a material gap in the material strand by means of the syringe element (18), ii) injecting an injection composition from the injection gap (20) into the material gap and the distribution hollow (22) such that the material strand comes into contact with the injection composition at the walls of the material gap and on the outside of the material strand guided along the wall surface (14) in order to obtain a modified material strand, iii) closing the material gap in the modified material strand by joining together the walls of the material gap that have come into contact with the injection composition in a joining region that is spaced apart from the syringe element (18) along the extrusion direction E.

10. The method according to claim 9, wherein, The strand-shaped vulcanizable rubber product is a tread blank or a ply cord of a tread blank.

11. A method for producing a vulcanized rubber product (24), the method comprising the method steps of the method for producing a strand-shaped vulcanizable rubber product as claimed in any one of claims 1 to 10, and the following step: iv) vulcanizing the strand-shaped vulcanizable rubber product or a rubber blank comprising the strand-shaped vulcanizable rubber product, wherein the vulcanizable rubber compound is vulcanized to obtain a vulcanized rubber product (24).

12. A vulcanized rubber product (24), having a rubber element comprising a vulcanized rubber compound, Among them, on at least one surface, the rubber element comprises modified regions (26a, 26b) extending on the surface along a covering direction B, wherein the rubber element comprises a modified layer (28) that is connected to the modified regions (26a, 26b) along the covering direction B and extends through the rubber element along a layer direction S, wherein the modified regions (26a, 26b) and the modified layer (28) comprise a vulcanized rubber material, the composition of which is different from the composition of the vulcanized rubber compound, wherein the average width of the modified layer (28) in an extension direction A, which is perpendicular to the covering direction B and perpendicular to the layer direction S, is 30 μm or less. Wherein, an average width of the modified layer (28) in the extension direction A is smaller than an average width of the modified region (26a, 26b), and the extension direction is perpendicular to the covering direction B and perpendicular to the layer direction S.

13. The vulcanized rubber product according to claim 12, wherein, On each of two opposite surfaces, preferably on the surface provided for road contact and on the surface facing away from said surface, the rubber element comprises a modified region (26) extending on the surface along the covering direction B, wherein the modified layer (28) is connected to two modified regions (26a, 26b).

Images