Method for producing a vehicle tyre blank, and corresponding vehicle tyre

Abstract

The invention relates to a method for producing a vehicle tyre blank (10), comprising the method steps of: a) producing or providing a starting composition, comprising: i) one or more rubber materials that are selected from the group consisting of isobutene-isoprene rubbers and halogenised isobutene-isoprene rubbers, and ii) one or more polyamides, b) extruding the starting composition at a temperature in the range from 220 to 290°C to obtain a mixed material, c) producing a flat material film (12) comprising the mixed material, d) contacting the flat material film (12) with a carcass layer (14) to produce a carcass laminate (16), wherein the carcass layer (14) comprises a plurality of reinforcing members (18) embedded in a vulcanisable rubber mixture, wherein the flat material film (12) is materially bonded to the carcass layer (14), and e) further processing the resulting carcass laminate (16) on a tyre assembly device and producing a vehicle tyre blank (10), wherein the vehicle tyre blank (10) comprises the carcass laminate (16).

Description

[0001] Method for producing a pneumatic vehicle tire blank and corresponding vehicle tires

[0002] Description

[0003] The invention relates to a method for producing a green vehicle tire, a method based thereon for producing a vulcanized vehicle tire, a green vehicle tire and a corresponding vulcanized vehicle tire.

[0004] The automotive industry is one of the sectors that has faced fundamental challenges since the beginning of the 21st century and has simultaneously been shaped by numerous technological innovations. Growing customer awareness of environmental aspects such as emissions profiles and resource efficiency requires new mobility concepts. At the same time, demand for improved vehicle performance and requirements regarding driving safety are increasing. Meeting these challenges is not solely the responsibility of the actual vehicle manufacturers. In practice, many of these aspects are strongly influenced by tire properties, making the optimization of tire properties an important area of ​​innovation.

[0005] Information on the technological background is disclosed, for example, in DE 102018207039 A1, WO 2008060302 A1, EP 2289993 B1, JP 2009298986 A, EP 2165824 B1 or US 2013338294 A1.

[0006] Many of the relevant driving characteristics of vehicle tires depend significantly on the rubber materials used. Of these, the rubber material of the tread, for example, is a key factor influencing rolling resistance and braking properties. In addition to the materials that come into direct contact with the road surface during later use, other components of a vehicle tire also contribute to the overall properties. One of these additional components of vehicle tires is the so-called inner layer, which is sometimes also referred to as the inner liner. In modern pneumatic vehicle tires, this inner layer serves primarily to prevent gas from escaping from the interior of the vehicle tire, thereby ensuring the necessary airtightness to make the use of previously common tire tubes superfluous.

[0007] Given this primary objective, a large part of the development of tire innerliner materials focuses heavily on their air permeability. However, the constant demand for further optimized vehicle tires, which also enable favorable rolling resistance and low energy consumption, requires further optimization of tire innerliners beyond airtightness.

[0008] Although the tire inner layer is often thinner than other tire layers, it still contributes to the overall weight of the tire. Furthermore, the inherent stiffness of the tire inner layer also influences the overall rolling resistance of the tire.

[0009] The primary object of the present invention was to eliminate or at least reduce the disadvantages of the prior art.

[0010] In particular, it was the object of the present invention to provide a method for producing a vehicle tire blank and a method based thereon for producing a vehicle tire, with which advantageous vehicle tires can be obtained.

[0011] In this respect, it was an object of the present invention that the vehicle tires obtained using the specified method should have improved rolling resistance and optimized weight. In this respect, it was an object of the present invention to minimize the amount of material that must be disposed of at the end of the vehicle tire's use.

[0012] Furthermore, it was an object of the present invention that the vehicle tires to be produced by the method to be specified should have excellent airtightness.

[0013] It was a further object of the present invention that the solution found to achieve the objects described above should be compatible with the typical manufacturing processes of modern pneumatic vehicle tires, in particular with manufacturing processes on tire building drums, which require the elevation of a tire carcass in the building process.

[0014] It was an additional object of the present invention that the tire blanks and vehicle tires that can be produced using the method to be specified should be as free as possible from defects, in particular air inclusions.

[0015] It was a supplementary object of the present invention that the processes to be specified should have the advantageous properties largely independent of the process parameters used for vulcanization, so that the solution found within the scope of the invention should be reliably applicable to a wide variety of vehicle tire types.

[0016] Furthermore, it was an object of the present invention to reduce the need for vulcanization systems in the production of vehicle tires, in particular those components which are classified as harmful to the environment and / or health, for example guanidine accelerators.

[0017] The inventors of the present invention have now found that the objects described above can surprisingly be achieved if a starting composition comprising isobutene-isoprene rubbers, which may optionally be halogenated, and polyamide is extruded in a specific temperature interval in order to form a flat material film from the resulting mixed material, which film can then be laminated to the inside of a tire carcass in order to assume the function of a tire inner layer in the vehicle tire blank or in the subsequent vehicle tire, as defined in the claims.

[0018] Surprisingly, the use of this flat material film made from the specific blend material allows for the production of particularly high-performance tire inner liners, which, despite a reduced average thickness compared to typical tire inner liners, exhibit excellent airtightness. The reduced thickness and reduced stiffness allow for an improvement in the overall weight of the vehicle tires produced with it, as well as their rolling resistance. The flat material film made from the specific blend material is advantageously well-suited for processing in typical tire building processes, particularly allowing for the elevation of the previously laminated carcass. The use of such an extensible, highly airtight material film allows for the production of advantageous pneumatic vehicle tires, in particular allowing the "splice" thickness to be significantly reduced.In this respect, the inventors have found that the advantages of the invention surprisingly become apparent even when the use of a vulcanization system is dispensed with in the mixed material, so that, for example, the need for potentially environmentally and / or health-damaging materials such as guanidine accelerators can be reduced. Advantageously, the material film made from the specific mixed material has excellent processing properties and can be laminated to a carcass ply in a time- and cost-efficient manner, whereby air inclusions can be avoided without great effort. The aforementioned objects are accordingly achieved by the subject matter of the invention, as defined in the claims. Preferred embodiments of the invention emerge from the subclaims and the following explanations.

[0019] Such embodiments, which are designated as preferred below, are combined in particularly preferred embodiments with features of other embodiments designated as preferred. Combinations of two or more of the embodiments designated as particularly preferred below are thus very particularly preferred. Likewise preferred are embodiments in which a feature of an embodiment designated as preferred to any extent is combined with one or more further features of other embodiments designated as preferred to any extent. Features of preferred green vehicle tires and vulcanized vehicle tires result from the features of preferred methods.

[0020] To the extent that both specific amounts or proportions of a mixture component, for example for the rubbers or polyamides, and preferred embodiments of the mixture component are disclosed below, the specific amounts or proportions of the preferably configured mixture components are also disclosed. Furthermore, it is disclosed that the corresponding specific total amounts or

[0021] Total proportions of the mixture components, at least a part of the mixture components can be preferably designed and in particular also that preferably designed mixture components can in turn be present in the specific amounts or proportions within the specific total amounts or total proportions.

[0022] The invention relates to a method for producing a green vehicle tire, comprising the process steps: a) producing or providing a starting composition comprising: i) one or more rubbers selected from the group consisting of isobutene-isoprene rubbers and halogenated isobutene-isoprene rubbers, and ii) one or more polyamides, b) extruding the starting composition at a temperature in the range of 220 to 290 °C to obtain a mixed material, c) producing a sheet-like material film comprising the mixed material, d) contacting the sheet-like material film with a carcass ply to produce a carcass laminate, wherein the carcass ply comprises a plurality of reinforcements embedded in a vulcanizable rubber mixture, wherein the sheet-like material film is integrally bonded to the carcass ply,and e) further processing the produced carcass laminate on a tire building device and producing a green vehicle tire, wherein the green vehicle tire comprises the carcass laminate.

[0023] The method according to the invention serves to produce a green vehicle tire, which, in accordance with the understanding of one skilled in the art, can subsequently be converted into a vehicle tire in the usual manner, in particular by vulcanizing the vulcanizable rubber mixtures contained in the green vehicle tire. An example of a method according to the invention is one in which the green vehicle tire is a green pneumatic vehicle tire, or in which the vehicle tire is a pneumatic vehicle tire.

[0024] In process step a), a starting composition is first prepared, for example by mixing the components, or provided, for example by purchasing a corresponding starting composition from a supplier. The starting composition comprises one or more rubbers selected from the group consisting of isobutene-isoprene rubbers and halogenated isobutene-isoprene rubbers, as well as one or more polyamides.

[0025] In accordance with standard practice, the components of the starting composition are each referred to as "one or more." The term "one or more" refers, as is customary in the industry, to the chemical nature of the respective compounds, not to their quantity. For example, the vulcanizable rubber compound may comprise exclusively polyhexamethylene adipamide as a polyamide, which would mean that the vulcanizable rubber compound comprises a plurality of the corresponding molecules.

[0026] Insofar as mass fractions are stated below, these are usually stated as combined mass fractions of one or more components in accordance with industry practice, thereby expressing that the mass fraction of the correspondingly formed components taken together meets the corresponding criteria.

[0027] According to the invention, the starting composition comprises specific rubbers, namely one or more rubbers selected from the group consisting of isobutene-isoprene rubbers and halogenated isobutene-isoprene rubbers. In this respect, a process according to the invention is preferred, wherein the one or more rubbers are selected from the group consisting of isobutene-isoprene rubbers.

[0028] Isobutene-isoprene rubbers are widely known to experts in the rubber processing industry and are often referred to as butyl rubber (HR).

[0029] Corresponding isobutene-isoprene rubbers are commercially available as typical synthetic rubbers from various manufacturers. A process according to the invention is preferred, wherein the one or more rubbers consist of monomer units derived from isobutene in a proportion ranging from 95% to 99%, based on the number of monomer units in the rubber.

[0030] Halogenated isobutene-isoprene rubbers are also generally known to those skilled in the rubber industry. These are also copolymers of isobutene and isoprene, with the isoprene units in the rubber being at least partially halogenated. When halogenated with chlorine or bromine, the skilled person also refers to them as chlorobutyl (CIIR) or bromobutyl (BIIR). These halobutyl rubbers represent the most industrially relevant halogenated isobutene-isoprene rubbers. Accordingly, a process according to the invention is also preferred, wherein the one or more rubbers are selected from the group consisting of isobutene-isoprene rubbers, chlorinated isobutene-isoprene rubbers, and brominated isobutene-isoprene rubbers.

[0031] In light of the above explanations, it is clear to the person skilled in the art that the isobutene-isoprene rubbers and halogenated isobutene-isoprene rubbers specified above are different materials that can be differentiated according to whether functional groups containing a halogen atom are present along the polymer chains. A corresponding differentiation is possible for the person skilled in the art using various analytical methods. In principle, for example, all methods that can be used to detect the presence of halogens in the material are suitable, in particular 35 CI-NMR and 79 Br NMR spectroscopy.

[0032] The second essential component in the starting composition is polyamide. Polyamides are also well known to those skilled in the rubber processing industry, where they are used primarily as materials for reinforcements. Suitable polyamides are commercially available from various manufacturers.

[0033] At least theoretically, it is also possible to use aromatic polyamides, so-called aramids, which could be particularly advantageous for applications in which high cutting loads are expected. However, in the inventors' opinion, it is particularly advantageous to use non-aromatic polyamides, in particular PA6 or PA6.6. Accordingly, a process according to the invention is preferred, wherein the one or more polyamides are selected from the group consisting of polycaprolactams, polyhexamethylene adipamides, and copolymers of these polymers, preferably selected from the group consisting of polyhexamethylene adipamides.

[0034] As is common practice in the rubber processing industry, in addition to the butyl rubbers or halobutyl rubbers and the polyamides, other components can also be included in the starting composition, for example, to adjust the physicochemical properties. However, since the inventors attribute the advantageous properties of the material films used in the process according to the invention to the advantageous combination of butyl rubber with polyamide, it is also preferred, in accordance with expert understanding, that the starting composition consists as largely as possible of these components.Accordingly, a process according to the invention is preferred wherein the combined mass fraction of the one or more rubbers and the one or more polyamides in the starting composition is 95% or more, preferably 98% or more, particularly preferably 99% or more, based on the mass of the starting composition or on the mass of the starting composition less the mass of fillers, preferably based on the mass of the starting composition. Additionally or alternatively, a process according to the invention is preferred wherein the combined mass fraction of additives that are not fillers in the starting composition is 5% or less, preferably 2% or less, particularly preferably 1% or less, based on the mass of the starting composition, preferably based on the mass of the starting composition less the mass of fillers.

[0035] In the inventors' opinion, it can be seen as a particular advantage of the process according to the invention that the starting composition does not have to be a vulcanizable rubber mixture, i.e., that the starting composition itself does not necessarily have to be vulcanizable and, for this purpose, accordingly does not have to comprise a vulcanization or crosslinking system. Accordingly, a process according to the invention is also preferred, wherein the combined mass fraction of crosslinking reagents in the starting composition is 1% or less, preferably 0.5% or less, particularly preferably 0.1% or less, based on the mass of the starting composition, preferably based on the mass of the starting composition less the mass of fillers.

[0036] In the inventors' opinion, the ratios of (halo)butyl rubber and polyamide can be adjusted quite freely by a person skilled in the art to suit the respective application requirements. However, the inventors have succeeded in identifying particularly preferred mass ratios and absolute mass fractions for the components, with which particularly advantageous blended materials can be obtained that ensure excellent airtightness and good processing properties with a low material thickness of the material films produced therefrom. In this respect, a process according to the invention is initially preferred, wherein the ratio of the combined mass fraction of the one or more rubbers to the combined mass fraction of the one or more polyamides in the starting composition is in the range from 70:30 to 30:70, preferably in the range from 60:40 to 40:60, particularly preferably in the range from 55:45 to 45:55.Additionally or alternatively, a process according to the invention is preferred, wherein the combined mass fraction of the one or more rubbers in the starting composition is in the range from 30 to 70%, preferably 40 to 60%, particularly preferably 45 to 55%, based on the mass of the starting composition, preferably based on the mass of the starting composition less the mass of fillers. Additionally or alternatively, a process according to the invention is preferred, wherein the combined mass fraction of the one or more polyamides in the starting composition is in the range from 30 to 70%, preferably 40 to 60%, particularly preferably 45 to 55%, based on the mass of the starting composition, preferably based on the mass of the starting composition less the mass of fillers.

[0037] As explained above, the inventors consider it particularly advantageous to form the starting composition as largely as possible from (halo)butyl rubber and polyamide. An exception to this principle, however, are fillers, which can be present in the starting composition and in the mixed material in order to further adapt the physicochemical properties to the respective application requirements and which are preferably not taken into account when calculating the mass fractions of the other components in the starting composition. Preference is given to a process according to the invention wherein the starting composition additionally comprises: iii) one or more fillers. Preference is given to a process according to the invention wherein the combined mass fraction of the one or more fillers in the starting composition is in the range from 1 to 20%, preferably 5 to 15%, based on the mass of the starting composition.

[0038] Among the various possible fillers, the inventors have recognized that the use of flat fillers made of gas-tight material is particularly advantageous. These flat fillers can, for example, be fillers in the form of platelets or flakes, the latter also being referred to by those skilled in the art as "flakes." These flat fillers ensure that, at a low layer thickness of the material film, the gas diffusion paths are artificially lengthened by the zigzag path around the flat fillers, i.e., without increasing the layer thickness. This allows particularly advantageous gas-tight properties to be achieved without having to increase the thickness of the material film.The inventors have found that the low thickness of the material film has a synergistic effect and promotes an advantageous alignment of the flat fillers, which, with low layer thicknesses, are predominantly aligned at least approximately parallel to the surface of the material film, so that a large surface coverage with gas-tight fillers results in a plan view of the surface of the material film. Suitable materials for the flat fillers include, in addition to metals and plastics known for their gas-tightness, in particular gas-tight natural materials such as lignin flakes. Accordingly, a process according to the invention is particularly preferred, wherein the one or more fillers are selected from the group consisting of platelet-shaped and flake-shaped, preferably flake-shaped, fillers.A process according to the invention is preferred, wherein the one or more fillers are selected from the group consisting of i) metals, for example aluminum or steel, ii) gas-tight plastics, for example polyesters, and iii) gas-tight natural materials, for example lignin.

[0039] In step b) of the process according to the invention, the prepared or provided starting composition is extruded. In accordance with the expert's understanding, extruding the starting composition at elevated temperatures leads to at least partial melting and mixing of the components. In principle, any type of extruder can be used for this purpose. However, a process according to the invention is preferred in which the extrusion takes place using a twin-screw extruder.

[0040] In principle, a process according to the invention is preferred, wherein the mixed material is a homogeneous mixed material.

[0041] The inventors have found that establishing a specific temperature range has proven necessary to produce a mixed material that is as homogeneous as possible and can be advantageously processed as a material film. This ensures the necessary airtightness as well as the advantageous processing properties that enable bubble-free lamination of the flat material film. In this respect, the inventors have succeeded in identifying particularly preferred temperature ranges for extrusion. A process according to the invention is preferred, wherein the extrusion of the starting composition takes place at a temperature in the range of 230 to 280°C, preferably in the range of 250 to 270°C, alternatively preferably in the range of 230 to 270°C.

[0042] In process step c), a flat material film comprising the mixed material is formed from the mixed material produced by extrusion. At least in theory, additives can be added to the mixed material during the production of the flat material film, for example, to adjust the processing properties. However, those skilled in the art will understand that, in accordance with the above explanations, it is particularly preferred for the flat material film to consist as largely as possible of the mixed material, so that it is also conceivable, for example, for the flat material film to be formed immediately after the extrusion step according to process step b).Accordingly, a method according to the invention is preferred, wherein the mass fraction of the mixed material in the flat material film is 95% or more, preferably 98% or more, particularly preferably 99% or more, very particularly preferably substantially 100%, based on the mass of the material film.

[0043] Those skilled in the field of plastics and rubber processing are familiar with the concept of flat films. In accordance with the expert's understanding, the term "flat material film" refers to a material that has a significantly greater dimension in two orthogonal spatial directions than in the third dimension orthogonal to this plane, i.e., a material whose thickness is very small relative to its surface area. Likewise, those skilled in the art, based on their specialist knowledge, are familiar with suitable plastics processing methods for forming plastic films from extrudates. Advantageously, the method according to the invention is, in principle, not limited with regard to the method used for film production.However, in the opinion of the inventors, a method according to the invention is preferred, wherein the production of the flat material film is carried out by shaping the mixed material with a rolling mill, in particular a calender.

[0044] It can be seen as a major advantage of the method according to the invention that the flat material films made of the specific mixed material allow excellent airtightness even at very low layer thicknesses, so that the resulting green tires and vehicle tires have a reduced overall weight. In order to actually utilize the advantages of the method according to the invention, it is accordingly preferred for essentially all embodiments of the invention to select a thickness with regard to the average thickness of the flat material film that is significantly lower than the average thickness of typical tire inner layers, which typically have a thickness of 1.6 mm at the time of application to the carcass.A method according to the invention is preferred, wherein the flat material film produced has an average thickness in the range from 0.05 to 0.8 mm, preferably in the range from 0.2 to 0.7 mm, particularly preferably in the range from 0.3 to 0.6 mm.

[0045] In process step d), the previously produced flat material film is combined with other components of the green vehicle tire. For this purpose, the flat material film is laminated to the tire carcass to create a carcass laminate. According to the expert understanding, this lamination means that the flat material film is brought into contact with the carcass, or more precisely, the carcass ply forming the surface of the tire carcass, and is bonded to the carcass ply in a material-to-material manner, for example, by pressure application. A method according to the invention is preferred, wherein the flat material film is bonded to the carcass ply in a material-to-material manner without the use of separate adhesives.Additionally or alternatively, a method according to the invention is preferred, wherein the flat material film is bonded to the carcass ply by pressure application at a temperature in the range from 40 to 150 °C, preferably in the range from 70 to 110 °C, wherein the pressure application is preferably carried out with a pressure in the range from 200 to 400 kPa, particularly preferably in the range from 250 to 350 kPa.

[0046] During lamination, other layers can also be arranged between the carcass layer and the material film, for example comparatively narrow strips of carcass rubber, which can provide additional reinforcement, particularly in the later shoulder area of ​​the vehicle tires.

[0047] The carcasses used in green vehicle tires and their basic structure are thoroughly familiar to those skilled in the art of tire manufacturing. These tire carcasses consist of at least one carcass ply, but may also have multiple carcass plies. Against this background, the present invention defines that the material film is laminated to a carcass ply, more precisely a carcass ply forming the surface, so that the presence of additional carcass plies in the tire carcass remains possible. In addition to the carcass ply, the carcass laminate can optionally also be partially or fully covered with additional layers, for example, plates, on the film side or carcass side, so that the carcass laminate can be a multi-layer carcass laminate, for example, with three or four layers, which advantageously allows extra work cycles to be avoided and / or the need for a cross-linking system to be reduced.

[0048] In this respect, the inventors consider a configuration of the method according to the invention to be particularly advantageous in which the carcass laminate, in addition to the carcass ply and the flat material film, comprises a further cover layer made of a vulcanizable rubber mixture, which is laminated at least in sections, preferably over the entire surface, over the flat material film. This cover layer can, for example, consist of the carcass rubber lining and have an average thickness in the range of 0.1 to 0.8 mm, preferably in the range of 0.15 to 0.7 mm. This results in the great advantage that the material film is bonded on both sides to a vulcanizable rubber mixture, whereby an advantageous and particularly resilient connection of the material film to the other components of the green vehicle tire can be achieved and the material film is also at least partially protected from mechanical stress, in particular surface defects.Accordingly, a method according to the invention is particularly preferred, wherein the produced carcass laminate is contacted with a cover layer on the side of the flat material film, wherein the cover layer comprises a vulcanizable rubber mixture, preferably the vulcanizable rubber mixture of the carcass layer, wherein the flat material film is materially bonded to the cover layer.

[0049] Those skilled in the art of tire manufacturing are also well-versed in the structure of typical carcass plies, and the present invention is not limited in this respect. Carcass plies typically comprise a plurality of reinforcements, also referred to as cords, embedded in a vulcanizable rubber mixture. Based on the inventors' experiments, the inventive method is not limited in terms of the design of the carcass ply, so that all typical materials for the reinforcements and the vulcanizable rubber mixture can advantageously be used, and the skilled person is free to select these materials with a view to their desired application requirements. An example of a method according to the invention is one in which the vulcanizable rubber mixture comprises one or more diene rubbers.An example of a process according to the invention is additionally or alternatively, wherein the vulcanizable rubber mixture comprises one or more fillers. An example of a process according to the invention is additionally or alternatively, wherein the vulcanizable rubber mixture comprises one or more additives selected from the group consisting of plasticizers, anti-aging agents, and coupling agents.By way of example, in addition or alternatively, a method according to the invention is again provided, wherein the reinforcements are selected from the group consisting of metallic and textile reinforcements, preferably textile reinforcements, particularly preferably textile reinforcements with at least one yarn, wherein the yarn consists of a material selected from the group consisting of aramid, polyethylene terephthalate, polyether ketone, polyketone, polyethylene naphthalate, rayon, viscose, carbon fibers, natural fibers, glass fibers and PBO (poly(p-phenylene-2,6-benzobisoxazole)), very particularly preferably selected from the group consisting of aramid and polyethylene terephthalate.

[0050] From the above definition that the carcass laminate is produced in process step d) before the carcass laminate is further processed on a tire building device in process step e), it follows that the lamination process must explicitly take place before the further processing of the carcass laminate. It follows from this that the positioning of the material film on the carcass ply has a significant influence on which parts of the subsequent green vehicle tire or vehicle tire are covered by the material film. Those skilled in the art in the field of tire production will understand that the bottommost carcass ply, i.e. the carcass ply that is laminated with the material film, is regularly wrapped around the bead cores or core tabs during the tire building process in order to form the bead areas of the green vehicle tire and the turn-up areas of the carcass ply.By completely covering the surface of the carcass ply, it is thus possible to obtain a green vehicle tire in which the outer sides of the ply turn-ups are also coated with the material film. In this case, this is a process according to the invention, wherein the contacting in process step d) is carried out such that the carcass ply in the carcass laminate is covered on one side by 95% or more, preferably 98% or more, particularly preferably 99% or more, and most particularly preferably essentially completely, with the material film, based on the surface of the carcass ply.Additionally or alternatively, a method according to the invention is also preferred, wherein the vehicle tire blank comprises on one or both sides a layer turn-up of the carcass ply around a bead element, wherein the surface of the carcass ply lying on the outside in the axial direction in the vehicle tire blank is formed at least partially, preferably predominantly, particularly preferably substantially completely, by the material film in the region of the layer turn-ups.

[0051] In the inventors' opinion, however, in view of the greatest possible weight reduction, it is preferable to arrange the material film only in the area in which it is actually needed for the sealing effect in the subsequent vehicle tire, and accordingly to avoid the additional weight that would arise from covering the ply turnups. The resulting arrangement, which in the subsequent tire thus only corresponds to a covering of the inside, is sometimes also referred to as a C1 / 2 arrangement. A method according to the invention is preferred for this purpose, wherein the contacting in method step d) takes place such that the carcass ply in the carcass laminate is covered on one side with the material film to 50 to 85%, preferably 60 to 80%, particularly preferably 70 to 80%, based on the surface of the carcass ply.Additionally or alternatively, a method according to the invention is preferred, wherein the material film is arranged on the carcass ply over the entire length of the carcass laminate, preferably centrally, wherein the width of the side regions lying on both sides of the material film and not covered by the material film differs particularly preferably by less than 20%, very particularly preferably by less than 10%, in particular preferably by less than 1%. Additionally or alternatively, a method according to the invention is also preferred, wherein the vehicle tire blank comprises a ply turn-up of the carcass ply around a bead element on one or both sides, wherein the surface of the carcass ply lying on the outside in the axial direction in the vehicle tire blank is covered by the material film in the region of the ply turn-ups to 10% or less, preferably to 1% or less, particularly preferably substantially not at all.As an alternative to the embodiment with layer turn-ups, a method according to the invention is also preferred, wherein the vehicle tire blank does not comprise a layer turn-up of the carcass ply around a bead element, so that the carcass ply extends between the two bead elements, wherein the surface of the carcass ply lying on the inside in the radial and axial direction in the vehicle tire blank is covered by the material film.

[0052] At the same time, the person skilled in the art will readily understand that in the vast majority of cases, the entire inside of the vehicle tire should be provided with an airtight layer over its entire circumference. When using the specific material film of the present invention, it is correspondingly expedient not to use it only in one part of the vehicle tire, for example in combination with a conventional tire inner layer, but rather to line the entire circumference of the vehicle tire accordingly, which during lamination means that the material film is applied over the entire length of the subsequently processed carcass laminate. Accordingly, a method according to the invention is preferred, wherein the radially inner surface of the green vehicle tire is formed by the material film, preferably to more than 98%, particularly preferably to more than 99%, very particularly preferably essentially completely.

[0053] In process step e), the previously produced carcass laminate is further processed into the desired green vehicle tire. For essentially all embodiments, a process according to the invention is preferred, wherein the tire building device is a tire building drum.

[0054] The regularly stranded carcass laminate is arranged on the tire building device during further processing. According to expert understanding, this usually requires the material to be closed into a ring. For this purpose, the ends of the carcass laminate are joined together in a material-to-material bond, which is also referred to by those skilled in the art as "splicing." Experts generally have the choice between so-called overlap or butt splicing.

[0055] In this respect, it can be seen as an advantage of the method according to the invention that the carcass laminate can be formed such that the applied material film protrudes at one end, so that after the ring closure it extends beyond the connection point. As a result, the flat material film covers the splicing area, thereby achieving advantageous durability and airtightness. In particular, this makes it easier to join the ends of the carcass laminate by butt splicing without reducing the gas tightness, since the flat material film promotes good bond formation. This is advantageous in many cases, since during butt splicing, no disruptive interactions between the strength members of the two ends of the carcass ply need to be taken into account.A method according to the invention is preferred, wherein in method step e) a splice, preferably a butt splice, is produced to form a ring closure between the ends of the carcass laminate.

[0056] Further processing in process step e) and the production of a green vehicle tire will, in the vast majority of cases, involve raising the carcass and subsequently bonding it to the tread package. Raising the carcass regularly occurs during carcass production. During the raising step, the stretchable material film is stretched so that the final thickness in the green vehicle tire is reduced compared to the thickness of the flat material film used. A method according to the invention is preferred, wherein process step e) comprises forming a green tire carcass by raising the carcass laminate, preferably by raising it by 20% or more, preferably by 30% or more.A method according to the invention is preferred, wherein the average thickness of the flat material film in the vehicle tire blank is in the range from 0.01 to 1.0 mm, preferably in the range from 0.09 to 0.6 mm, particularly preferably in the range from 0.15 to 0.4 mm.

[0057] The subsequent step of joining the carcass to the tread package, which is sometimes also referred to as "cambering", involves the further expansion of the tire carcass prepared as described above against a tread package arranged above it, which in addition to the actual treads, in many cases can also include additional reinforcement layers, for example belt bandages.

[0058] The invention also relates to a method for producing a vulcanized vehicle tire, comprising the method steps of the method according to the invention for producing a green vehicle tire, as well as the method step: f) vulcanizing the green vehicle tire with vulcanization of the vulcanizable rubber mixture to obtain a vulcanized vehicle tire.

[0059] Here, the green vehicle tire is vulcanized using the process commonly used in the tire industry, for example by sulfur-based crosslinking in a vulcanization mold.

[0060] The invention further relates to a green vehicle tire, preferably produced or producible by the method according to the invention, comprising: x) a green tire carcass having at least one carcass ply, wherein the carcass ply comprises a plurality of reinforcements embedded in a vulcanizable rubber mixture, y) a green tread located radially outward relative to the green tire carcass, and z) a material film comprising a mixed material, wherein the mixed material is producible by extrusion of a starting composition at a temperature in the range of 230 to 290 °C, wherein the starting composition comprises: i) one or more rubbers selected from the group consisting of isobutene-isoprene rubbers and halogenated isobutene-isoprene rubbers, and ii) one or more polyamides, wherein the material film is integrally bonded to the carcass ply,and wherein the radially inner surface of the vehicle tire blank is formed by the material film or a cover layer covering the material film (12) and bonded thereto.

[0061] Finally, the invention also relates to a vulcanized vehicle tire, produced or producible by the method according to the invention for producing a green vehicle tire and / or produced or producible by vulcanization of the green vehicle tire according to the invention.

[0062] The invention and preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying figures.

[0063] Fig. 1 is a schematic representation of process step d) of the process according to the invention in a preferred embodiment.

[0064] Fig. 2 is a schematic cross-sectional view through the

[0065] Carcass laminate during the formation of a butt splice. Fig. 3 shows a schematic representation of a green vehicle tire after production using the method according to the invention in a preferred embodiment.

[0066] Fig. 1 shows process step d) of the method according to the invention for producing a green vehicle tire 10 in a preferred embodiment. The flat material film 12, previously produced from a starting composition comprising butyl rubber and polyamide by extrusion at a temperature in the range of 220 to 290 °C, is applied centrally to the surface of a carcass ply 14, which can be unwound from a roll, for example. The dashed line in Fig. 1 indicates the separating cut with which the produced carcass laminate 16 can be separated from the roll in order to feed it to the further tire building process. In Fig. 1, it can be seen that the flat material film 12 protrudes slightly beyond the carcass ply 14 at one end, whereas the separating cut is made at a small distance from the material film 12. This arrangement makes it particularly easy to create an advantageous butt splice.

[0067] The production of a corresponding butt splice during the ring closure of the carcass laminate 16 is schematically illustrated in Fig. 2. Fig. 2 shows a schematic cross-section through the two ends of the carcass laminate 16 in the region of the ring closure. The carcass ply 14 contains a plurality of reinforcement members 18 embedded in a vulcanizable rubber mixture, which are indicated as circles in Fig. 2. The projecting flat material film 12 makes it particularly easy to butt splice the two ends of the carcass laminate 14, with the material film 12 covering the resulting connection area between the ends of the carcass ply 14.

[0068] Fig. 3 shows, in a highly simplified, schematic representation, an exemplary green vehicle tire 10 as can be obtained at the end of process step e) of the method according to the invention. The produced carcass laminate 16, which in the example shown comprises a carcass ply 14 and a material film 12 laminated thereon, is wrapped on both sides around a bead core 24 with a core tab 26 arranged thereon. The carcass laminate 16 was raised on the tire building drum against a tread package consisting of a green tread 22 and a belt ply 28 arranged underneath to obtain the final green vehicle tire 10, which can then be vulcanized, for example, in a vulcanization mold and provided with a profile in the tread.

[0069] The process according to the invention was tested in practice and the vehicle tires produced with it were evaluated with regard to their advantageous properties:

[0070] For this purpose, a starting composition consisting of 50% isobutene-isoprene rubber and 50% polyamide PA6 was converted into a homogeneous blend using a KraussMaffei Group ZE25A X54D twin-screw extruder at an average temperature of 240 °C. A flat material film with an average thickness of 0.5 mm was produced from this blend. This film was laminated to a standard carcass fabric (two twisted polyester cords, each with a linear weight of 1400 dtex).

[0071] The resulting carcass laminate was cambered against a tread pack on a tire building drum, so that the flat material film extended from one bead area to the other. The vehicle tires obtained from this green tire by vulcanization exhibited a reduced weight and advantageous rolling resistance compared to conventionally manufactured vehicle tires with a standard inner liner. Furthermore, the airtightness of the vehicle tires produced according to the invention was determined compared to an otherwise identical reference in which a conventional tire inner layer made of a butyl rubber compound with a thickness of 1.5 mm was used instead of the material film.

[0072] In the test, pressure loss was determined as a 30-day pressure loss under ambient conditions, with the values ​​obtained as the average of three measurements. For this purpose, the tire is mounted on a rim and stored on a shelf under constant conditions for six weeks. The measured air loss is then converted into pressure loss per 30 days.

[0073] For the tires produced according to the invention with the film-based inner liner, a pressure loss of only 3.7% was advantageously measured after 30 days, despite the low layer thickness. Even though this value is higher than the 2.5% pressure loss observed for the reference with a standard inner liner, this is a positive result given the significantly reduced layer thickness. If a lower pressure loss were required for pneumatic vehicle tires produced according to the invention, this could easily be achieved by slightly increasing the layer thickness and / or adding flat fillers.

[0074] List of reference symbols

[0075] 10 vehicle tire tubes

[0076] 12 material foil

[0077] 14 carcass ply 16 carcass laminate

[0078] 18 strength members

[0079] 20 tire carcass blanks

[0080] 22 Tread blank

[0081] 24 Bead core 26 Core vane

[0082] 28 Belt position

Claims

Claims 1. A method for producing a green vehicle tire (10), comprising the method steps: a) producing or providing a starting composition comprising: i) one or more rubbers selected from the group consisting of isobutene-isoprene rubbers and halogenated isobutene-isoprene rubbers, and ii) one or more polyamides, b) extruding the starting composition at a temperature in the range from 220 to 290 °C to obtain a mixed material, c) producing a sheet-like material film (12) comprising the mixed material, d) contacting the sheet-like material film (12) with a carcass ply (14) to produce a carcass laminate (16), wherein the carcass ply (14) comprises a plurality of strength members (18) embedded in a vulcanizable rubber mixture, wherein the sheet-like material film (12) is integrally bonded to the carcass ply (14) is connected,and e) further processing the produced carcass laminate (16) on a tire building device and producing a vehicle tire blank (10), wherein the vehicle tire blank (10) comprises the carcass laminate (16).

2. A process according to claim 1, wherein the combined mass fraction of the one or more rubbers in the Initial composition is in the range of 30 to 70%, based on the mass of the initial composition.

3. A process according to any one of claims 1 or 2, wherein the combined mass fraction of the one or more polyamides in the starting composition is in the range of 30 to 70%, based on the mass of the starting composition.

4. A process according to any one of claims 1 to 3, wherein the starting composition additionally comprises: iii) one or more fillers.

5. The method of claim 4, wherein the one or more fillers are selected from the group consisting of platelet-shaped and flake-shaped fillers.

6. A process according to any one of claims 1 to 5, wherein the extrusion of the starting composition takes place at a temperature in the range of 230 to 280 °C.

7. Method according to one of claims 1 to 6, wherein the produced flat material film (12) has an average thickness in the range of 0.05 to 0.8 mm.

8. A method for producing a vulcanized vehicle tire, comprising the method steps of the method for producing a green vehicle tire (10) according to one of claims 1 to 7, and the method step: f) vulcanizing the green vehicle tire (10) while vulcanizing the vulcanizable rubber mixture to obtain a vulcanized vehicle tire.

9. A vehicle tire green comprising: x) a tire carcass green (20) with at least one carcass ply (14), wherein the carcass ply (14) comprises a plurality of reinforcements (18) embedded in a vulcanizable rubber mixture, y) a tread green (22) located radially outward relative to the tire carcass green (20), and z) a material film (12) comprising a mixed material, wherein the mixed material can be produced by extrusion of a Starting composition at a temperature in the range of 220 to 290 °C, wherein the starting composition comprises: i) one or more rubbers selected from the group consisting of isobutene-isoprene rubbers and halogenated isobutene-isoprene rubbers, and ii) one or more polyamides, wherein the material film (12) is integrally bonded to the carcass ply (14), and wherein the radially inner surface of the vehicle tire blank (10) is formed by the material film (12) or a cover layer is formed covering the material film (12) and bonded thereto.

10. Vulcanized vehicle tire, manufactured or producible by the method according to claim 8 and / or manufactured or producible by Vulcanization of the green vehicle tire (10) according to claim 9.

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