VULCANIZABLE COMPOSITION FOR THE MANUFACTURE OF A VULCANIZATION BELLOWS

Description

[0001] The invention relates to a vulcanizable composition for producing a vulcanization bladder, a vulcanizate producible by vulcanizing a corresponding vulcanizable composition, a vulcanization bladder for use in the vulcanization of vehicle tires, a vulcanization device for vulcanizing vehicle tires, and the use of a corresponding vulcanization bladder in the vulcanization of vehicle tires. Also disclosed are the use of a corresponding vulcanizable composition in the production of vulcanization bladders and a method for producing vehicle tires.

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

[0003] The production of high-performance pneumatic vehicle tires is an area of ​​technology that has undergone numerous improvements and developments in recent decades, enabling the provision of ever-better high-performance products that meet ever-increasing demands.

[0004] One of the final production steps in the manufacture of modern pneumatic vehicle tires usually involves the vulcanization of the uncured green tire, the so-called "green tire." This is typically done by placing the tire, largely assembled from its individual components but not yet vulcanized, into a vulcanization device. This typically includes a vulcanization mold into which the green tire is placed. The mold has a textured surface on its inside to transfer the future tread pattern to the vehicle tire.

[0005] To ensure that the tire fills the mold correctly and that the tread pattern provided on the inside of the vulcanization mold is fully transferred to the vulcanized tire, it is necessary to press the green tire into the mold and the tread pattern on the sidewalls during the vulcanization process. In practice, this is achieved using a vulcanization bladder, also known as a heating bladder. This inflatable vulcanization bladder is placed inside the green tire so that it can expand into the interior of the carcass in such a way that the green tire is pressed outwards into the vulcanization mold. In practice, the vulcanization bladder is pressurized with a hot process gas, such as steam, during vulcanization in order to supply the green tire to be vulcanized with the thermal energy required for vulcanization from the inside.

[0006] The vulcanization bladder therefore plays a particularly important role in the manufacturing process of modern pneumatic vehicle tires. At the same time, the rubber vulcanization bladder is subject to high stresses, particularly thermal and mechanical stresses, and is also constantly exposed to the process gas. As a result, vulcanization bladders can usually only be used for a limited number of vulcanization cycles. Given the costs associated with replacing a vulcanization bladder and the labor required for changing or continuously quality-checking aging vulcanization bladders, vulcanization bladders make a significant contribution to the overall costs of tire production.

[0007] In addition, in the event of a material failure in the vulcanization bladder during vulcanization, production defects can occur, leading to unwanted rejects in tire production.

[0008] Even if a macroscopic crack in the vulcanization bladder does not occur, it can be observed in practice that the quality of pneumatic vehicle tires manufactured with aged vulcanization bladders deteriorates at a certain point, resulting in a risk that the required specifications will no longer be met. This deterioration in tire quality when using aged vulcanization bladders has been observed particularly for pneumatic vehicle tires whose carcass contains rayon.

[0009] While the pneumatic vehicle tire itself, especially its structure and materials, has been the focus of development for years, the vulcanization bladders used in its production have received comparatively little attention.

[0010] GB 870947A discloses a vulcanizable rubber composition comprising a butyl rubber, a halogenated butyl rubber, a highly unsaturated rubbery copolymer of a conjugated diolefin with styrene and a 2,6-dimethylol-4-hydrocarbon substituted phenol, which may be in the monocyclic or multicyclic (polymeric) state.

[0011] EP 1914063A1 relates to an expandable vulcanization bladder for use in vulcanizing rubber products. The bladder consists of an inner layer and an outer layer. The inner layer comprises a rubber composition comprising, based on parts by weight per 100 parts by weight of rubber (phr), an isobutylene copolymer rubber selected from butyl rubber and / or halobutyl rubber, wherein the butyl rubber comprises a copolymer of isobutylene and isoprene containing from about 0.5 to about 5 weight percent units derived from isoprene; wherein the halobutyl rubber is a halogenated butyl rubber comprising a chlorinated or brominated copolymer of isobutylene and isoprene containing from about 0.5 to about 5 weight percent units derived from isoprene, and wherein the outer layer comprises a rubber composition comprising a silicone rubber.

[0012] US 2005112223A1 relates to an expandable vulcanization bladder made of a butyl rubber composition containing a microencapsulated polysiloxane lubricant to impart lubricity to the bladder's surface. The invention also relates to a method for vulcanizing tires using such a bladder.

[0013] US 2018133985A1 relates to a method for producing a tire curing bladder, the method comprising the steps of (i) providing a vulcanized tire curing bladder; and (ii) applying an air barrier composition to the vulcanized tire curing bladder to form an air barrier layer. A method for restoring air retention of a tire curing bladder, the method comprising the steps of (i) providing a used tire curing bladder; and (ii) applying an air barrier composition to the used tire curing bladder to form an air barrier layer.

[0014] EP 1078955A1 relates to expandable butyl rubber bladders for use in vulcanization presses for hydrocarbon rubbers such as pneumatic tires. The bladders consist of a crosslinked elastomer consisting of repeating isobutylene units, and the bladder composition contains lecithin, particularly a modified lecithin, preferably in liquid form, dispersed in the bladder composition. The bladder composition may also contain castor oil, corn oil, and / or soybean oil. The bladder composition may further contain at least one of the following materials: graphite and polytetrafluoroethylene powder.

[0015] The invention also relates to a method for vulcanizing tires using such a butyl rubber bladder.

[0016] The central object of the present invention was to eliminate or at least mitigate the disadvantages of the prior art described above.

[0017] It was therefore the object of the present invention to provide a vulcanization bellows and a method for its production which has excellent mechanical properties and has a particularly long service life under thermal and / or mechanical stress.

[0018] The vulcanization bellows to be specified should show a high vapor retention, i.e. a low vapor permeability, even after many vulcanization cycles, especially when using steam as the process gas.

[0019] It was desirable that the vulcanization bladder to be specified not only withstands the occurring loads for many vulcanization cycles, but also that the pneumatic vehicle tires produced with the vulcanization bladder have as consistent and advantageous a quality as possible even after a high number of vulcanization cycles.

[0020] In this respect, it was a supplementary requirement that the vulcanisation bladders to be specified should, in particular, have a high degree of compatibility with pneumatic vehicle tyres in whose carcass the material rayon is used, since, according to the inventors' knowledge, these are particularly susceptible to defects that can occur when using aged vulcanisation bladders.

[0021] Based on this, it was an important object of the present invention to provide a vulcanizable composition and a vulcanizate that can be produced therefrom, from which a corresponding vulcanization bladder with the advantages described above can be obtained.

[0022] In light of the above, it was a supplementary object of the present invention to provide a vulcanization device for vulcanizing vehicle tires.

[0023] Likewise, the use of an appropriate vulcanization bellows should be specified when vulcanizing vehicle tires.

[0024] The inventors of the present invention have recognized that the above-mentioned objects can surprisingly be achieved if the vulcanizable composition used to produce the vulcanization bladders is adapted in a specific manner, as disclosed below.

[0025] In particular, to achieve the above-described objectives, it is important to adapt the vulcanizable composition used for production, which in the prior art mostly consists of isobutene-isoprene rubber in combination with chloroprene rubber. The inventors of the present invention have recognized that to achieve the above-described objectives, a vulcanizable composition must be used that has a high content of isobutene-isoprene rubber and, in addition, a specific content of halogenated isobutene-isoprene rubbers.

[0026] The above-mentioned objects are accordingly achieved by vulcanizable compositions, vulcanizates, vulcanization bellows, vulcanization devices, uses, and methods as defined in the claims and disclosed below. Preferred embodiments of the invention emerge from the subclaims and the following statements.

[0027] Those features of inventive articles that are designated as preferred below are combined in particularly preferred embodiments with other features 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 designated as preferred to any extent is combined with one or more further features designated as preferred to any extent. Features of preferred vulcanizates, vulcanization bellows, vulcanization devices, uses, and processes according to the invention emerge from the features of preferred vulcanizable compositions.

[0028] The invention relates to a vulcanizable composition for the production of a vulcanization bladder, comprising: one or more halogenated isobutene-isoprene rubbers in a total amount ranging from 2 to 15 phr, and one or more isobutene-isoprene rubbers in a total amount ranging from 85 to 98 phr.

[0029] The vulcanizable composition according to the invention is suitable for the production of vulcanization bellows. In accordance with the expert understanding, the term "vulcanizable" means that the vulcanizable composition can be crosslinked and converted into a vulcanizate upon application of thermal energy and, if appropriate, pressure. Thus, in addition to the rubbers defined above, the vulcanizable composition comprises further constituents that serve at least to enhance the vulcanizability of the system. In contrast to the rubbers defined above, however, the vulcanizable composition according to the invention is very flexible with regard to the additives used for this purpose, so that the vulcanizable composition can contain further constituents, as also specified below.In vulcanizable compositions according to the invention, vulcanization is usually carried out using activators, for example, zinc oxide, for example in combination with suitable crosslinking systems. Corresponding vulcanization processes using metal oxides, such as those used for crosslinking chloroprene rubber, are generally known to those skilled in the art.

[0030] The term phr (parts per hundred parts of rubber by weight) used in this application is the standard quantity used in the rubber industry for compound formulations. The dosage of the parts by weight of the individual substances is always based on 100 parts by weight of the total mass of all rubbers present in the mixture.

[0031] The vulcanizable composition according to the invention comprises isobutene-isoprene rubber, similar to some prior art vulcanizable compositions for the production of vulcanization bladders. However, in the inventors' estimation, a particularly high proportion of isobutene-isoprene rubber must be used.

[0032] Isobutene-isoprene rubber, also referred to as butyl rubber and regularly assigned the abbreviation IIR, is known to those skilled in the art of rubber processing. It is a synthetic rubber produced by copolymerizing isobutene and isoprene. Several different isobutene-isoprene rubbers can be used in the vulcanizable compositions according to the invention, which may differ, for example, in their isoprene content. However, it is important that the total amount of these isobutene-isoprene rubbers be within the range specified above.

[0033] In addition to the isobutene-isoprene rubber, the vulcanizable composition according to the invention comprises halogenated isobutene-isoprene rubber. 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 refers to them as chlorobutyl (CIIR) or bromobutyl (BIIR).

[0034] 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 based on whether functional groups containing a halogen atom are present along the polymer chains. Such differentiation is possible for the person skilled in the art using various analytical methods. In principle, for example, all methods that can detect the presence of halogens in the material are suitable, in particular 35< Cl NMR and 79< Br NMR spectroscopy.

[0035] Using corresponding vulcanizable compositions according to the invention, vulcanizates can be obtained by vulcanization, i.e., by crosslinking the components, from which vulcanization bladders with excellent properties, in particular excellent resistance to thermal stress and exposure to water vapor, can be obtained. The corresponding vulcanization bladders according to the invention can advantageously be used for a large number of vulcanization cycles in the production of pneumatic vehicle tires before they need to be replaced. In practice, it has been shown that vehicle tires with excellent properties can still be obtained even after numerous vulcanization cycles, even when rayon is used in the green tires or their carcasses.

[0036] Starting from the basic inventive idea, the inventors of the present invention were able to identify certain mutually complementary regions for the rubber components to be provided in the vulcanizable composition, with which particularly advantageous vulcanizates and corresponding vulcanization bladders can be obtained.

[0037] Preference is given to a vulcanizable composition according to the invention comprising one or more halogenated isobutene-isoprene rubbers in a total amount in the range from 3 to 12 phr, preferably in the range from 5 to 10 phr. Accordingly, preference is given to a vulcanizable composition according to the invention comprising one or more isobutene-isoprene rubbers in a total amount in the range from 88 to 97 phr, preferably in the range from 90 to 95 phr.

[0038] The inventors were also able to identify suitable components with regard to the chemical nature of the rubbers. A vulcanizable composition according to the invention is preferred, wherein at least one of the halogenated isobutene-isoprene rubbers, preferably all of the halogenated isobutene-isoprene rubbers in the vulcanizable composition, has a proportion of isoprene-derived repeating units in the range of 1 to 5%, preferably in the range of 2 to 4%, based on the total number of repeating units. Likewise preferred is a vulcanizable composition according to the invention, wherein at least one of the isobutene-isoprene rubbers, preferably all of the isobutene-isoprene rubbers in the vulcanizable composition, has a proportion of isoprene-derived repeating units in the range of 1 to 5%, preferably in the range of 2 to 4%, based on the total number of repeating units.

[0039] For the halogenated isobutene-isoprene rubber to be used according to the invention, it has proven particularly advantageous to use the chlorinated and / or brominated component, with chlorinated isobutene-isoprene rubber being particularly preferred in the opinion of the inventors. Accordingly, a vulcanizable composition according to the invention is preferred, wherein at least one of the halogenated isobutene-isoprene rubbers, preferably all of the halogenated isobutene-isoprene rubbers in the vulcanizable composition, is selected from the group consisting of chlorinated and brominated isobutene-isoprene rubbers, preferably selected from the group consisting of chlorinated isobutene-isoprene rubbers.

[0040] In this regard, the inventors of the present invention have found that it is very particularly preferred if the vulcanizable composition according to the invention consists essentially, preferably exclusively, of the rubber components defined above. Accordingly, a vulcanizable composition according to the invention is preferred in which the total amount of halogenated isobutene-isoprene rubbers and isobutene-isoprene rubbers is 95 to 100 phr, preferably 98 to 100 phr, particularly preferably 99 to 100 phr, very particularly preferably 100 phr.

[0041] For certain embodiments, particularly when process gases other than steam are to be used, it may, however, be advantageous to optimally adjust the physicochemical properties of the vulcanizable composition according to the invention to the respective requirements of the application by adding small amounts of other diene rubbers. For certain applications, a vulcanizable composition according to the invention comprising one or more further diene rubbers in a total amount in the range from 0 to 13 phr, preferably 0 to 9 phr, particularly preferably 0 to 5 phr is therefore preferred. Diene rubbers are rubbers that are produced by polymerization or copolymerization of dienes and / or cycloalkenes and thus have C=C double bonds either in the main chain or in the side groups.Preferably, the further diene rubber is selected from the group consisting of natural polyisoprene, synthetic polyisoprene, epoxidized polyisoprene, butadiene rubber, solution-polymerized styrene-butadiene rubber, emulsion-polymerized styrene-butadiene rubber, polynorbornene, ethylene-propylene-diene rubber, nitrile rubber, acrylate rubber, silicone rubber, polysulfide rubber, epichlorohydrin rubber, styrene-isoprene-butadiene terpolymer, hydrogenated acrylonitrile-butadiene rubber and hydrogenated styrene-butadiene rubber, wherein the deinrubber is particularly preferably selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), solution-polymerized styrene-butadiene rubber (SSBR) and emulsion-polymerized styrene-butadiene rubber (ESBR).

[0042] According to the inventors' findings, with regard to the aging behavior of the vulcanizates and vulcanization bellows producible from the vulcanizable composition according to the invention, it is particularly advantageous to keep the content of chloroprene rubber in the vulcanizable composition low. The chloroprene rubber regularly used in the prior art is, in accordance with the expert's understanding, chlorobutadiene rubber, which can be produced by polymerizing chloroprene, i.e., 2-chloro-1,3-butadiene, and which regularly bears the abbreviation CR. Accordingly, a vulcanizable composition according to the invention is preferred wherein the total amount of chloroprene rubber in the vulcanizable composition is less than 5 phr, preferably less than 3 phr, particularly preferably less than 1 phr.

[0043] In particularly preferred embodiments, the vulcanizable composition according to the invention also contains a phenol-formaldehyde resin that can function as a crosslinking system. Using appropriate phenol-formaldehyde resins in the appropriate total amounts, the inventors' own experiments have shown excellent performance parameters for the vulcanization bladders that can be produced. The use of octylphenol-formaldehyde resins has proven particularly useful here, as the inventors believe they have particularly high compatibility with the halogenated isobutene-isoprene rubbers used, as well as the non-halogenated isobutene-isoprene rubbers. Thus, a vulcanizable composition according to the invention comprising one or more phenol-formaldehyde resins, which can be produced by reacting formaldehyde with a substituted or unsubstituted phenol, in a total amount in the range from 5 to 15 phr, is preferred.Particularly preferred is a vulcanizable composition according to the invention comprising one or more phenol-formaldehyde resins which can be prepared by the reaction of formaldehyde with a substituted or unsubstituted phenol, in a total amount in the range of 6 to 13 phr, preferably in the range of 7 to 11 phr.In this respect, a vulcanizable composition according to the invention is also preferred, wherein at least one of the phenol-formaldehyde resins, preferably all of the phenol-formaldehyde resins in the vulcanizable composition, are selected from the group consisting of phenol-formaldehyde resins which can be prepared by reacting formaldehyde with a substituted phenol, preferably an alkylphenol, wherein preferably at least one of the phenol-formaldehyde resins, preferably all of the phenol-formaldehyde resins, are selected from the group consisting of phenol-formaldehyde resins which can be prepared by reacting formaldehyde with octylphenol, preferably 4-tert-octylphenol.

[0044] Against the background of the above, the inventors of the present invention have succeeded in identifying a particularly preferred vulcanizable composition according to the invention, with which particularly advantageous properties could be achieved, particularly with regard to crack formation and crack propagation in the material. Preferred is a vulcanizable composition according to the invention comprising: one or more halogenated isobutene-isoprene rubbers in a total amount in the range of 5 to 10 phr, one or more isobutene-isoprene rubbers in a total amount in the range of 90 to 95 phr, and one or more phenol-formaldehyde resins which can be prepared by the reaction of formaldehyde with a substituted or unsubstituted phenol, in a total amount in the range of 7 to 11 phr.

[0045] In order to achieve particularly advantageous tear properties for the vulcanizates and vulcanization bladders produced from the vulcanizable compositions according to the invention, it is particularly preferred to provide fillers in the vulcanizable composition. The inventors believe that the use of carbon black is particularly advantageous, especially because it allows a higher thermal conductivity to be achieved compared to silica-filled mixtures. Thus, a vulcanizable composition according to the invention comprising one or more fillers in a total amount in the range from 10 to 150 phr, preferably in the range from 30 to 100 phr, is preferred, wherein preferably at least one of the fillers, preferably all of the fillers in the vulcanizable composition, is carbon black.

[0046] Carbon black is a non-polar filler and is particularly preferably used in amounts of 40 to 100 phr, even more preferably in amounts of 40 to 80 phr. It is again particularly preferred if the vulcanizable composition contains 57 to 67 phr of carbon black. This achieves particularly good mixing properties with regard to tear properties. The carbon black used preferably has an iodine adsorption number according to ASTM D 1510 of 30 to 110 mg / g, particularly preferably 60 to 110 mg / g, and very particularly preferably 70 to 90 mg / g. The DBP number according to ASTM D 2414 of the carbon black used is preferably 20 to 100 ml / 100g, particularly preferably 50 to 100 ml / 100g, and very particularly preferably 60 to 80 ml / 100g. Such a carbon black, with which particularly good properties can be achieved in the vulcanizable compositions according to the invention, is, for example, a carbon black of the type N 326 (iodine adsorption number = 82 mg / g; DBP number = 72 ml / 100g).

[0047] The vulcanizable composition may additionally or alternatively contain a polar filler. All polar fillers known to those skilled in the art, such as aluminum hydroxide, titanium dioxide, magnesium oxide, precipitated silica, and phyllosilicates, can be used as polar fillers. Silicon oxide-based fillers, such as silica, are preferably used as polar fillers. Silica is preferably used as the polar filler. The terms "silica" and "silica" are used synonymously within the scope of the present invention and in accordance with the understanding of those skilled in the art and each refer to silicon dioxides. The silicas used in the rubber industry are generally precipitated silicas, which are characterized in particular by their surface.For characterization, the nitrogen surface area (BET, method according to Brunauer, Emmett, Teller) according to DIN ISO 9277 and DIN 66132 is given as a measure of the inner and outer filler surface in m 2< / g and the CTAB surface area according to ASTM D 3765 is given as a measure of the outer surface, which is often regarded as the rubber-effective surface, in m 2< / g.

[0048] The silicas preferably used in vulcanizable compositions according to the invention have a nitrogen surface area of ​​greater than or equal to 100 m 2 / g, preferably between 100 and 250 m 2 / g, particularly preferably between 140 and 200 m 2 / g. Furthermore, the silicas used have a CTAB surface area of ​​between 100 and 200 m 2 / g, preferably between 120 and 180 m 2 / g, and particularly preferably between 140 and 180 m 2 / g.

[0049] It can be considered an advantage of the vulcanizable composition according to the invention that, according to the inventors' assessment, its physicochemical properties can be specifically modified and adapted to the respective requirements by adding further additives without impairing the high resistance observed according to the invention. In this context, a vulcanizable composition according to the invention comprising one or more additives in a total amount in the range from 1 to 100 phr, preferably in the range from 5 to 70 phr, particularly preferably in the range from 10 to 30 phr, is preferred, wherein the additives are selected from the group consisting of reinforcing resins, coupling agents, plasticizers, antiozonants, antiaging agents, UV stabilizers, and processing aids.

[0050] Resorcinol-formaldehyde resins, for example resorcinol-hexamethoxymethylmelamine resins (HMMM) or resorcinol-hexamethylenetetramine resins (HEXA), or modified phenolic resins can be used as reinforcing resins.

[0051] To improve processability and to bond silica and other polar fillers, if present, to the rubber, coupling agents can be used in the vulcanizable composition. Coupling agents can, in principle, be any coupling agents known to the person skilled in the art. The coupling agents, preferably silane coupling agents, are preferably used in amounts of up to 20 phr, preferably in amounts of 0.1 to 15 phr, particularly preferably in amounts of 0.5 to 10 phr.

[0052] Amounts of up to 20 phr, preferably amounts of 0.1 to 10 phr, particularly preferably amounts of 0.1 to 5 phr, of at least one plasticizer may also be present in the vulcanizable composition. This plasticizer is preferably selected from the group consisting of mineral oils, synthetic plasticizers, fatty acids, fatty acid derivatives, plasticizer resins, factices, glycerides, terpenes, biomass-to-liquid oils (BTL oils), and rubber-to-liquid oils (RTL oils). Plasticizer resins are understood to mean, in particular, hydrocarbon resins that are not reinforcing resins.

[0053] Anti-aging agents are compounds known to those skilled in the art for this purpose, such as N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), or 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ). Mastication aids are, for example, compounds such as 2,2'-dibenzamidodiphenyl disulfide (DBD).

[0054] The activators are, for example, zinc oxide, stearic acid, or salts thereof. The amount of zinc oxide in the vulcanizable composition is preferably 0.1 to 10 phr, more preferably 2 to 10 phr, and most preferably 2 to 6 phr. The vulcanizable composition according to the invention can contain, for example, stearic acid or salts thereof in amounts of up to 1 phr.

[0055] The advantage of the above-described vulcanizable composition according to the invention is that vulcanizates can be produced from it by vulcanization, which possess advantageous physicochemical properties. Accordingly, the vulcanizates produced from corresponding vulcanizable compositions according to the invention are also considered particularly advantageous. Vulcanization is carried out in accordance with the expert's understanding using established methods, for example, by using metal oxide as activators. Vulcanization is advantageously carried out in a temperature range of 120 to 240 °C, preferably 140 to 220 °C.

[0056] The invention thus also relates to a vulcanizate which can be produced by vulcanizing a vulcanizable composition according to the invention.

[0057] In accordance with the understanding of those skilled in the art, the vulcanizate is defined here by the starting materials used for its preparation, as stated above for the vulcanizable composition according to the invention. As with all disordered materials, such as polymers, this is the only practical way to efficiently describe the resulting material, since structural characterization is virtually impossible.

[0058] Accordingly, the use of a vulcanizable composition according to the invention in the production of vulcanizates according to the invention and vulcanization bladders according to the invention for use in the vulcanization of vehicle tires, in particular vehicle tires comprising the material rayon, in particular in the carcass, is also disclosed.

[0059] Vulcanization bladders according to the invention can be obtained from the vulcanizate obtained, for example, by vulcanization as described above. These vulcanization bladders according to the invention are particularly advantageous because they exhibit particularly high durability when used in the production of pneumatic vehicle tires and remain usable even after numerous vulcanization cycles without adversely affecting the properties of the pneumatic vehicle tires produced with them.

[0060] The invention thus also relates in particular to a vulcanization bellows for use in the vulcanization of vehicle tires, in particular in the vulcanization of passenger car, truck and special tires, comprising a vulcanizate according to the invention.

[0061] According to the invention, the vulcanization bladder according to the invention comprises the vulcanizate obtained from the vulcanizable composition according to the invention by vulcanization. In a particularly preferred embodiment, the vulcanization bladder according to the invention consists essentially entirely of this vulcanizate, ie, it comprises no further components.

[0062] In an alternative embodiment, however, the vulcanization bellows according to the invention may comprise, in addition to the vulcanizate according to the invention, further components, for example struts and / or reinforcing cords, which impart additional structure and / or stability to the vulcanization bellows.

[0063] Since the advantages described above are evident when using the vulcanization bladders according to the invention in the vulcanization of vehicle tires, the use of corresponding vulcanization bladders in the production of vehicle tires is correspondingly advantageous.

[0064] The invention thus also relates to the use of a vulcanization bladder according to the invention in the vulcanization of vehicle tires, in particular vehicle tires comprising the material rayon, for extending the maintenance and / or replacement interval of the vulcanization device.

[0065] Surprisingly, it has proven particularly advantageous that the reusability of vulcanization bladders according to the invention is particularly high, even in the production of vehicle tires comprising the material rayon. According to the inventors' assessment, corresponding vehicle tires comprising the material rayon are in practice regularly particularly susceptible to defects that can occur when using aged vulcanization bladders. Without wishing to be bound by this theory, the inventors of the present invention assume that this is due to the unwanted escape of water vapor from the vulcanization bladder, e.g., through diffusion or through minute cracks, which leads to a change in the modulus in the hygroscopic rayon, which can adversely alter the properties of the produced pneumatic vehicle tire.

[0066] However, with a vulcanization bladder according to the invention comprising the vulcanizate according to the invention, which can be produced by vulcanization from the vulcanizable composition according to the invention, a particularly advantageous vapor retention can be achieved, which persists even over many vulcanization cycles. The inventors of the present invention suspect this to be one of the reasons for the improved performance of the vulcanization bladders according to the invention in the production of vehicle tires comprising the material rayon.

[0067] When using vulcanization bellows according to the invention in the vulcanization of vehicle tires, an extension of the maintenance and / or replacement interval of the vulcanization device used is advantageously achieved.

[0068] In light of the above, it is clear to those skilled in the art that the invention also relates to a vulcanization device that, in addition to a conventional vulcanization mold, also comprises a vulcanization bladder according to the invention. Accordingly, the invention relates to a vulcanization device for vulcanizing vehicle tires, comprising a vulcanization mold and a vulcanization bladder according to the invention.

[0069] In particularly preferred embodiments, the vulcanization device according to the invention can further comprise further vulcanization bellows according to the invention, which are provided as reserve and replacement parts for the vulcanization bellows according to the invention.

[0070] Also disclosed is a method for producing vehicle tires comprising the steps: A) introducing an unvulcanized vehicle tire into the vulcanization mold of a vulcanization device according to the invention, comprising a vulcanization bladder according to the invention for fitting into the interior of the unvulcanized vehicle tire, and B) vulcanizing the unvulcanized vehicle tire, wherein the vulcanization bladder according to the invention is expanded by an introduced process gas, preferably steam, in order to press the unvulcanized vehicle tire against the preferably structured inner wall of the vulcanization mold.

[0071] The disclosed method for producing vehicle tires is particularly advantageous because it can be operated in a particularly time- and cost-efficient manner through the use of vulcanization bladders according to the invention or a vulcanization device according to the invention which comprises the vulcanization bladders according to the invention, since the vulcanization bladders have to be replaced less frequently and thus a larger number of vehicle tires can be produced per time, which advantageously have particularly consistent properties, even if the vulcanization bladder according to the invention has already been used in several vulcanization cycles.

[0072] Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying experimental data.

[0073] Vulcanizable compositions V1 and E1 were provided, the composition of which is summarized in Table 1. The vulcanizable compositions are produced according to the process commonly used in the rubber industry in a laboratory tangential mixer. Initially, a base mixture containing all components except the vulcanization system (sulfur and vulcanization-influencing substances) is prepared in one or more mixing stages. The vulcanizable composition is created by adding the vulcanization system in a final mixing stage. Table 1 Components Unit V1 E1 Chlorinated isobutene-isoprene rubber a)< phr - 10 Isobutene-isoprene rubber b)< phr 95 90 Chloroprene rubber c)< phr 5 - Soot d)< phr 54 54 Castor oil e)< phr 5 5 Plasticizers f)< phr 4 4 Zinc oxide g)< phr 5 5 Zinc stearate h)< phr 1 1 Fatty acid derivatives i)< phr 1 1 Octylphenol formaldehyde j)< phr 9 9 a) CBK-139 from NIZHNEKAMSKNEFTEKHIM, b) X_BUTYL RB 301 from ARLANXEO, c) NEOPRENE WM-1 from DENKA PERFORMANCE ELASTOMER LLC, d) CORAX N 220 from KG DEUTSCHE GASRUSSWERKE GMBH, e) CASTOR OIL from FAUTH, f) STRUKTOL 40 MS-F from SCHILL+SEILACHER "STRUKTOL" GmbH, g) ZNO S-6 from SLOVZINK, h) LIGASTAR ZN 101 C from PETER GREVEN GMBH & CO KG, i) PAT 757 / C from WUERTZ GMBH & CO. KG, j) SL-7015 Modified from Sino Legend Chemical Co., Ltd.

[0074] Vulcanizates were prepared from these vulcanizable compositions by vulcanization at 210 °C (13 min, isothermal). The physical properties of the vulcanizable compositions and the resulting vulcanizates are summarized in Table 2. Table 2 Sizes Unit V1 E1 Networking time min 17 14,4 Mooney viscosity (ML1+4) Mooney units 83,6 81,2 Tensile strength MPa 13,3 14,6 Elongation at break % 776,4 742,4 Force (300% elongation) MPa 4,5 5,4 Hardness (Shore A, RT) Shore A 59,6 56,1 Rebound resilience (RT) % 9,2 8,4 Pass rate (fresh) g / (m 2 < d) 0,2 0,2 Pass rate (steam aged) g / (m 2 < d) 0,5 0,3 Vapor retention capacity (48 h at 200 °C) % 64,70 68,59

[0075] Unless otherwise stated, the standards and measurement regulations listed below refer to the version valid on 1 July 2021.

[0076] The Mooney viscosity at room temperature was determined using a rotor according to DIN 53 523 according to ASTM D 1646 BS ISO 289.

[0077] The Shore A hardness at room temperature was determined according to DIN 53 505.

[0078] The elongation at break, the force at 300% elongation and the rebound resilience were determined using a ring geometry according to DIN 53504-R1 (density determination of the ring according to DIN EN ISO 1183-2) in a measuring method according to DIN ISO 5725 or DIN 53512:2000-04 using a test device type 5109 from Zwick.

[0079] The transmission rates and vapor retention capacity were determined according to ASTM F-1249 using a Mocon Permatran-W 3 / 33, where the value in g / (m 2< d) indicates how many grams per day pass through one square meter.

[0080] In addition, crack initiation (at 1024 cycles) and crack propagation (at 512 cycles) were investigated on steam-aged samples (48 h at 200 °C) according to ISO 132. Table 3 Sizes Unit V1 E1 De Mattia crack formation Crack Class 1 - 6 0 Crack class 2 - 1 0 De Mattia crack continuation Crack length 1 mm 25 10 Crack length 2 mm 25 10

[0081] From the above measurement data it is evident that particularly advantageous vulcanizates can be obtained by vulcanization with vulcanizable compositions according to the invention, which are excellently suited for use in vulcanization bellows.

[0082] In particular, low permeation rates and high vapor retention capacity are advantageously observed for vulcanizates according to the invention. The data compiled in Table 3 also show that, compared to the prior art, excellent values ​​are achieved with vulcanizates according to the invention in terms of crack initiation, and that crack propagation is significantly reduced in materials according to the invention.

Claims

1. Vulcanizable composition for producing a vulcanization bladder, comprising: - one or more halogenated isobutene-isoprene rubbers in a total amount in the range from 2 to 15 phr and - one or more isobutene-isoprene rubbers in a total amount in the range from 85 to 98 phr.

2. Vulcanizable composition according to Claim 1, comprising one or more halogenated isobutene-isoprene rubbers in a total amount in the range from 3 to 12 phr, preferably in the range from 5 to 10 phr.

3. Vulcanizable composition according to either of Claims 1 or 2, comprising one or more isobutene-isoprene rubbers in a total amount in the range from 88 to 97 phr, preferably in the range from 90 to 95 phr.

4. Vulcanizable composition according to any of Claims 1 to 3, wherein at least one of the halogenated isobutene-isoprene rubbers, preferably all of the halogenated isobutene-isoprene rubbers in the vulcanizable composition, are selected from the group consisting of chlorinated and brominated isobutene-isoprene rubbers, preferably are selected from the group consisting of chlorinated isobutene-isoprene rubbers.

5. Vulcanizable composition according to any of Claims 1 to 4, comprising one or more phenol-formaldehyde resins producible by reaction of formaldehyde with a substituted or unsubstituted phenol in a total amount in the range from 5 to 15 phr, preferably in the range from 6 to 13 phr, particularly preferably in the range from 7 to 11 phr.

6. Vulcanizable composition according to any of Claims 1 to 5, comprising one or more fillers in a total amount in the range from 10 to 150 phr, preferably in the range from 30 to 100 phr, wherein preferably at least one of the fillers, preferably all of the fillers, in the vulcanizable composition, are carbon black.

7. Vulcanizate producible by vulcanization of a vulcanizable composition according to any of Claims 1 to 6.

8. Vulcanization bladder for use in the vulcanization of vehicle tires, especially in the vulcanization of car, truck and specialty tires, comprising a vulcanizate according to Claim 7.

9. Vulcanization apparatus for vulcanization of vehicle tires, comprising a vulcanization mold and a vulcanization bladder according to Claim 8.

10. Use of a vulcanization bladder according to Claim 8 in the vulcanization of vehicle tires, especially of vehicle tires comprising the material rayon, for extending the maintenance and / or replacement interval of the vulcanization apparatus.