Tread and method for forming a tread for producing a tire for a motor vehicle

Abstract

A tread (10) for producing a tire for a motor vehicle comprises a first tread section (11) and a second tread section (12), each having a first mixing element (11) and a second mixing element (14). The respective first mixing element (13) is arranged on the respective second mixing element (14) with respect to a stacking direction (S) of the tread (10). The tread further comprises a third mixing element (15) which, with respect to a running direction (L) of the tread (10), is arranged between the first tread section (11) and a second tread section (12) and connects them to one another. The third mixing element (15) is in contact with the respective second mixing element (14) and is contact-free with the respective first mixing element (13).

Description

The present invention relates to a tread for producing a tire for a motor vehicle and to a motor vehicle having such a tread. The present invention further relates to a method of forming a tread for manufacturing a tire for an automobile.Vehicles have tires that usually have a rubber component in the form of a rubber tread. Such a rubber tire is manufactured from a tread which is usually manufactured by means of an extruder. A raw material is charged through a hopper and processed in the extruder. A rotating screw mixes the material and conveys it to an exit. Subsequently, the material can be further processed as a material web or tread for tire production. In the production of tires or associated starting products, it is always a concern to keep costs low and, in addition, to be able to produce a safe and reliable tire.It is an object underlying the invention to provide or make a tread which can contribute to a production of a secure tire.The object is achieved in each case by the features of the independent patent claims. Advantageous further developments are specified in the dependent patent claims.According to one aspect of the invention, a tread for manufacturing a tire for a motor vehicle comprises a first tread portion and a second tread portion, each comprising a first mixing element and a second mixing element. The respective first mixing element is arranged or formed on the respective second mixing element with respect to a stacking direction of the tread. The tread also comprises a third mixing element which is arranged or formed between the first tread section and a second tread section with respect to a running direction of the tread and connects these to one another. The third mixing element is configured to be in contact with the respective second mixing element and free of contact with the respective first mixing element.By means of the described structure of the tread, it is possible to contribute to cost-effective and reliable production of a secure tire. The tread comprises a plurality of mixing elements which are formed differently in particular with regard to material compositions and physical properties. The tread makes it possible, by means of a simple and clear structure, to comply with regulatory safety requirements, as are specified, for example, with respect to electrostatic charging of a motor vehicle and corresponding discharge capabilities of the latter. For example, a tire permitted for road traffic should have an electrical conductivity that corresponds to an electrically conductive resistance of less than 10^10 ohms.The tread is designed in particular in the form of a material web as a rubber or rubber component and has the three or more mixing elements. The first mixing element is formed in particular by a profile mixture which establishes the contact with the roadway in a tire. The second mixing element forms a base for the first mixing element, so that the second mixing element can also be referred to as a base mixture and the first mixing element as a coating or cap mixture. The third mixing element forms a central strip between the two raceway sections, which central strip contains in particular a predefined proportion of soot. The third mixing element can also be referred to as a carbon central strip or with the English term "carbon center beam". In the following description, the terms profile mixture, base mixture and carbon median strip are therefore also used, inter alia, for the first, second and third mixing elements.It is a finding in connection with the present invention that the carbon center strip serves as a conductor for electrostatic charges and is accordingly intended to have a predefined electrical conductivity. Furthermore, the carbon central strip should also impart a certain tackiness in order to enable a secure and reliable bond of the mixing elements. By means of the described structure of the tread, both a relatively high electrical conductivity and a reliable tackiness and a secure cohesion of the components of the tread can be realized. This can contribute to increased safety of the motor vehicle and in road traffic. This is established in particular by the contact of the carbon central strip with the base mixture and the intentionally established non-contact with the profile mixture, which permits significantly less tackiness with respect to the carbon central strip than the base mixture.According to a development of the tread, the respective second mixing element is designed such that it has a side wall which extends between the respective first mixing element and the third mixing element with respect to the running direction. The side walls of the second mixing elements each cover a side wall of the associated first mixing element and, with respect to the stacking direction, form a channel or a type of chimney in which the third mixing element is formed. In a ready-to-use and rolling tire, the carbon center strips and the side walls of the base mixture would then have a short-term contact with the roadway surface during rolling. A particularly reliable electrical lead can thus be established. If the carbon central strip or the third mixing element has an interruption or a defect, an electrical lead-off is furthermore provided by one or both side walls of the base mixture or of the second mixing element, even if the electrical conductivity is lower than that of the carbon central strip.According to a further development of the tread, the mixing elements each have a predefined electrical conductivity, wherein the electrical conductivity of the third mixing element is greater than that of the second mixing element, and the electrical conductivity of the second mixing element is greater than that of the first mixing element. The carbon central strip or the third mixing element has, for example, an electrical conductivity, the value of which is between 250% and 1250% inclusive of the value of the electrical conductivity of the second mixing element. The second mixing element has, for example, an electrical conductivity whose value is at least twice as great as the value of the electrical conductivity of the first mixing element. Thus, a reliable electrical conductivity of the tread and of the subsequent tire can be established. The electrical conductivity of the respective mixing element can be influenced in particular by the proportion of carbon black in the starting material.According to a further development of the tread, a starting material for forming the third mixture element has a Mooney viscosity of between 3-40 inclusive. Because the carbon central strip only has contact with the base mixture, a particularly liquid starting material can also be provided for forming the third mixture element, so that a broader field of application for viscous materials is provided. For example, the starting material for the third mixing element has a Mooney viscosity of less than or equal to 40, 30, 20, 10 or 5.The third mixing element can also be designed to be particularly narrow and have a width of 0.1-10.0 mm with respect to the running direction. The side walls of the second mixing element can also be made narrow and each have a width of 0.5-10.0 mm.According to a further aspect of the invention, a motor vehicle comprises a tire which has a configuration of the tread described above. By virtue of the fact that the motor vehicle comprises an embodiment of the tread, advantages and properties described in connection with the tread are also disclosed for the motor vehicle and vice versa.According to a further aspect of the invention, a method for forming a tread for producing a tire for a motor vehicle comprises providing a respective starting material for forming the first mixture element, the second mixture element and the third mixture element. The starting materials are designed differently in particular with regard to electrical conductive resistances or electrical conductivities, so that the mixing elements formed in each case have different electrical conductivities. The method further comprises forming the first tread portion by forming the first and second mixture elements such that the first mixture element is arranged on the second mixture element with respect to the stacking direction of the tread. The method further comprises forming the second tread portion by forming a further first and a further second mixture element, such that the further first mixture element is arranged on the further second mixture element with respect to the stacking direction. The method also comprises forming the third mixture element such that the third mixture element is arranged between the first and the second tread section with respect to the running direction of the tread and connects these to one another. The third mixture element is formed so as to be in contact with the respective second mixture element and free of contact with the respective first mixture element of the two tread portions.In particular, the previously described embodiments of the tread can be produced by means of the method described, so that advantages and properties described in connection with the tread are also disclosed for the method and vice versa. The method steps described can, if technically realizable, take place successively or substantially simultaneously. Preferably, the three mixtures are extruded simultaneously in a co-extrusion process by means of an extrusion tool. Alternatively, for example, the two tread sections can be produced and subsequently the connecting third mixture element introduced into a gap between the two tread sections.In the tire industry, the manufactured tire must have a certain electrical conductivity and meet certain target values according to regulatory requirements. The decisive factor for this is that the tread which is in contact with the road is also conductive. To establish a reliable electrical conductivity, the carbon center strip can be made of a mixture that does not correspond to the base mixture or the profile mixture. It is a finding in connection with the present invention that when forming a conventional electrically conductive center strip, it is relatively thin and may not be present continuously in the tire profile. This relates in particular to an expansion between the outer side and the inner side of the tire. Furthermore, there is a challenge to establish reliable tackiness to the other blends, in particular the profile blend. The tackiness serves in particular for the reliable retention of the tire with respect to its self-contained tread.There are a plurality of possible profile mixtures that the first mixing element can realize. It is correspondingly expensive to form a mixture for the central strip which meets the requirements described above with respect to all available profile mixtures. However, there are currently a significantly smaller number of available base mixtures which are used to form the second mixing element. In addition, the available base mixtures permit significantly higher tackiness to the carbon central strip. Due to the described structure of the tread and the contact of the carbon central strip with the base mixture, reliable tackiness is achieved and, in addition, reliable electrical conductivity and dissipation are established.In particular, the carbon center strip can be produced by means of an individual mixture which lies between the conductive mixtures which form the respective second mixture element or the base mixture of the first and second tread segment. Thus, requirements for tackiness need only be fulfilled for relatively few mixtures of the second mixing element and, in addition, the side walls of the respective second mixing element form an electrically conductive securing means. Thus, a risk of electrically non- or poorly conductive tires can be significantly reduced.Exemplary embodiments of the invention are explained below with reference to schematic drawings. The following are shown: FIGS. 1-2 show an exemplary embodiment of a tread for producing a tire for a motor vehicle in various views, FIG. 3 shows a flow chart for a method for forming the tread according to FIGS. 1 and 2, and FIG. 4 shows an exemplary embodiment of a system for forming the tread according to FIGS. 1 and 2.FIG. 1 shows schematically in a side view an exemplary embodiment of a tread 10 for producing a tire for a motor vehicle. FIG. 2 shows the tread 10 according to FIG. 1 in a schematic plan view. The tread 10 has a first tread portion 11 and a second tread portion 12. The two tread sections 11, 12 each have a first mixing element 13 and a second mixing element 14, wherein the respective first mixing element 13 is arranged or formed on the respective second mixing element 14 with respect to a stacking direction S of the tread 10. The tread 10 also comprises a third mixing element 15 which is arranged between the first tread portion 11 and the second tread portion 12 with respect to a running direction L of the tread 10 and connects these to one another. The third mixing member 15 is formed to be in contact with the respective second mixing member 14 and free of contact with the respective first mixing member 13.The respective second mixing element 14 has a side wall 17 which covers a side wall 16 of the associated first mixing element 13. The side wall 17 of the respective second mixing element 14 is formed such that it extends between the respective first mixing element 13 and the third mixing element 15 with respect to the running direction L. The side walls 17 of the respective second mixing element thus form, with respect to the stacking direction S, a channel or a type of chimney which extends predominantly longitudinally along a transverse direction T of the tread 10 transversely to the running direction L. The third mixing element 15 thus only or predominantly has contact with the second mixing element 14 and thus enables a cost-effective and reliable production of a secure tire which can be formed in a beneficial manner, in particular with regard to material balance and physical properties, such as electrical conductivity. The third mixing element 15 may extend along the entire cross section of the tread 10, as illustrated in FIG. 2, or partially, so that it is surrounded laterally along the longitudinal direction L by the side walls 17. The side walls 17 of the second mixing elements 14 can thus alternatively form a closed frame around the third mixing element 15 according to a plan view as in FIG. 2.The tread 10 is designed in particular in the form of a material web as a rubber or rubber component and has the mixing elements 13, 14 and 15. The first mixing element 13 is formed in particular by a profile mixture which establishes the contact with the roadway in a tire. The second mixing element 14 forms a base for the first mixing element 13, so that the second mixing element 14 can also be referred to as a base mixture and the first mixing element 13 as a coating or cap mixture. The first mixing element 13 thus forms a later outer circumferential surface and the second mixing element 14 forms an inner circumferential surface of the tire. The third mixing element 15 forms a central strip between the two raceway sections 11, 12. The third mixing element 15 can also be referred to as a carbon central strip or with the English term "carbon center beam".The mixing elements 13, 14, 15 are designed in particular in a predefined manner with regard to a respective electrical conductivity, wherein the electrical conductivity of the third mixing element 15 is significantly greater than that of the second mixing element 14, which in turn is greater than that of the first mixing element 13. The third mixing element 15 thus provides a reliable electrical discharge in the tire and, in addition, the side walls 17 of the respective second mixing element 14 enable an electrical discharge. With respect to the above term alternatives, there is a higher tackiness between the carbon center strip and the base mixture than between the carbon center strip and the coating mixture. Because the carbon central strip is in contact with the base mixture and not in contact with the coating mixture, the tread section 11, 12 can thus contribute to improved retention and, in addition, a reliable electrical conductivity can be set up for discharging electrostatic charge of a corresponding motor vehicle.FIG. 3 shows a flow chart for a method for manufacturing the tread 10 for producing a tire for a motor vehicle, which can be carried out, for example, by means of a system 1 according to FIG. 4. In a step S 1, respective starting materials for forming the first, second and third mixture elements 13, 14, 15 are provided.In a step S 2, the respective starting materials are fed to the system 1, which comprises an extruder 2, for example a cold feed extruder, in which a screw element for processing the fed material or the respective mixture is arranged. The respective mixture is fed into a container 3 of the extruder 2 and mixed by means of the screw element in a screw cylinder 4 and driven along a mass processing direction or the running direction L to an outlet 5 of the screw cylinder 4. The worm element is driven and set in rotation by means of a drive unit 6, for example an electric motor. After the processed mass leaves through the outlet 5, the tread strip 10 is shaped, for example, by means of a plurality of guide channels and / or forming tools, and a material web for producing a tire for a motor vehicle is thus provided.In step S 2, the respective mixing elements 13, 14 and 15 can be configured to be parallel or offset in time. Preferably, the mixing elements 13, 14, 15 are extruded simultaneously in a co-extrusion process by means of an extrusion tool.Alternatively, for example, in step S 2, first the second mixing elements 14 having side walls 17 may be formed. In a further step S 3, the first mixing elements 13 can then be formed subsequently on the respective second mixing elements 14. In a further step S 4, the third mixture element 15 can then subsequently be formed as a carbon central strip, which connects the tread sections 11, 12 to the respective first and second mixture elements 13, 14.List of reference characters1 System 2 Extruder 3 Container 4 Screw cylinder with screw element 5 Outlet of screw cylinder 6 Drive unit 10 Tread 11 First tread section 12 Second tread section 13 First mixing element 14 Second mixing element 15 Third mixing element 16 Sidewall of first mixing element 17 Sidewall of second mixing element L Running direction of tread S Stacking direction of tread T Transverse direction of tread

Claims

Tread (10) for producing a tire for a motor vehicle, having: - a first tread section (11) and a second tread section (12), which each comprise a first mixing element (13) and a second mixing element (14), wherein the respective first mixing element (13) is arranged on the respective second mixing element (14) with respect to a stacking direction (S) of the tread (10), and - a third mixing element (15), which is arranged between the first tread section (11) and the second tread section (12) with respect to a running direction (L) of the tread (10) and connects these to one another, wherein the third mixing element (15) is formed in contact with the respective second mixing element (14) and without contact with the respective first mixing element (13).Tread (10) according to Claim 1, in which the respective second mixing element (14) is formed in such a way that it has a side wall (17) which extends between the respective first mixing element (13) and the third mixing element (15) with respect to the running direction (L).Tread (10) according to Claim 2, in which the side walls (17) of the respective second mixing element (14) form, with respect to the stacking direction (S), a channel in which the third mixing element (15) is formed.Tread (10) according to one of the preceding claims, in which the respective mixing elements (13, 14, 15) each have a predefined electrical conductivity, wherein the electrical conductivity of the third mixing element (15) is greater than that of the second mixing element (14), and the electrical conductivity of the second mixing element (14) is greater than that of the first mixing element (13).Tread (10) according to one of the preceding claims, in which the third mixing element (15) has an electrical conductivity, the value of which is between 250% - 1250% inclusive of the value of the electrical conductivity of the second mixing element (14).Tread (10) according to one of the preceding claims, in which the second mixing element (14) has an electrical conductivity whose value is at least twice as great as the value of the electrical conductivity of the first mixing element (13).Tread (10) according to one of the preceding claims, in which a starting material for forming the third mixture element (15) has a Mooney viscosity of between 3-40 inclusive.Tread (10) according to one of the preceding claims, in which the third mixing element (15) has a width of 1-10 mm with respect to the running direction (L).Motor vehicle, comprising: a tyre comprising a tread (10) according to one of the preceding claims.Method for forming a tread (10) for producing a tire for a motor vehicle, comprising: - providing a respective starting material for forming a first mixture element (13), a second mixture element (14) and a third mixture element (15), - forming a first tread section (11) by forming the first and the second mixture element (13, 14) such that the first mixture element (13) is arranged on the second mixture element (14) with respect to a stacking direction (S) of the tread (10), - forming a second tread section (12) by forming a further first and a further second mixture element (13, 14) such that the further first mixture element (13) is arranged on the further second mixture element (14) with respect to the stacking direction (S) of the tread (10), and - forming the third mixing element (15) such that the third mixing element (15) is arranged between the first tread section (11) and the second tread section (12) with respect to a running direction (L) of the tread (10) and connects these to one another, and the third mixing element (15) is formed in contact with the respective second mixing element (14) and without contact with the respective first mixing element (13).

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