Sulphur-curable rubber mixture for producing a component of a pneumatic vehicle tire, pneumatic vehicle tires and uses of the sulfur-curable rubber mixture

Abstract

Sulfur-curable rubber compound, preferably for the manufacture of a component of a vehicle pneumatic tire, comprising: - 100 phr of at least one type of rubber, - at least one processing aid, - at least one vulcanizing agent - Stearic acid and - 1 to 200 phr of at least one inorganic material, wherein the inorganic material comprises at least one metal cation, wherein the inorganic material consists of at least one compound selected from the group consisting of huntite and hydromagnesite.

Description

[0001] The invention relates to a sulfur-curable rubber compound for manufacturing a component of a vehicle tire. The invention also relates to a vehicle tire comprising the sulfur-curable rubber compound and uses of the sulfur-curable rubber compound.

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

[0003] Pneumatic tires maintain their function by being filled with air. However, in the event of a puncture, the air often escapes from the tire. When deflated, pneumatic tires can only bear the load for a short time. Driving with a flat tire typically leads to rapid tire failure, preventing a vehicle with a puncture from traveling far enough to reach the nearest repair shop.

[0004] Various rubber compounds are known in the state of the art: US 2011 / 0180301 A1 discloses compositions comprising a polymer and an anti-flame agent. EP 2 331 349 B1 discloses a rubber mixture comprising 30 to 100 phr of at least one halobutyl rubber and 5 to 100 phr of a dry mixture compound containing at least 25% of at least one delaminated aluminohydrosilicate modification. Further state of the art is disclosed in DE 10 2017 223 541 A1, DE 198 34 804 A1, DE 11 2013 005 994 T5, DE 10 2017 206 374 A1, EP 1 607 408 A1 and DE 600 13 750 T2.

[0005] One objective of the invention is to provide a rubber compound or a vulcanized component, for example a component of a vehicle pneumatic tire, which remains ready for use for a longer period during a breakdown.

[0006] This problem is solved according to the invention by a sulfur-crosslinkable rubber compound, preferably for the production of a component of a vehicle pneumatic tire, comprising: - 100 phr of at least one type of rubber, - at least one processing aid, - at least one vulcanizing agent - Stearic acid and - 1 to 200 phr of at least one inorganic material, wherein the inorganic material comprised at least one metal cation, wherein the inorganic material consisted of at least one compound selected from the group consisting of huntite and hydromagnesite.

[0007] In connection with the invention, a sulfur-curable rubber compound, preferably for the manufacture of a component of a vehicle pneumatic tire, is disclosed, comprising: - 100 phr of at least one type of rubber, - at least one processing aid, - at least one vulcanizing agent and - 1 to 200 phr of at least one inorganic material, wherein the inorganic material comprises at least one metal cation.

[0008] A particular achievement of the present invention is the recognition that the function of a vehicle tire during a puncture, i.e., when deflated, is primarily caused by high thermal energy. This friction usually occurs between the inner surface of the tire and the rim. Not infrequently, this even leads to the tire catching fire. Therefore, a particularly significant achievement of the present invention was the ability to produce a sulfur-curable rubber compound with an inorganic material which, when used in a vehicle tire, allows it to remain functional for a longer period during a puncture.The use of an inorganic material in a rubber compound according to the invention in an amount of 1 to 200 phr has the technical effect of reducing the rate of temperature rise or the maximum temperature reached in the heated rubber compound according to the invention within a tire during a puncture. This has the advantage that the vehicle tire with a rubber compound according to the invention remains functional for a longer period during a puncture.

[0009] Basically, the term "inorganic material" encompasses all chemical compounds and chemical compositions that do not contain carbon in their molecular formula, and additionally includes carbonates, carbon nanotubes and graphene.

[0010] Within the scope of the present invention, the term ‘metal cation’ does not include the cations of the semimetals of the periodic table, nor the cations of germanium, antimony or polonium.

[0011] Within the scope of the present invention, the inorganic material consists of at least one compound selected from the group consisting of huntite and hydromagnesite.

[0012] A rubber compound as disclosed above is preferred, wherein the rubber compound - 1 to 20 phr of at least one processing aid and / or - comprising 1 to 10 phr of at least one vulcanizing agent.

[0013] Within the scope of the present invention, vulcanizing agents are, for example, S, ZnO, and preferably the vulcanizing agents also include vulcanization accelerators.

[0014] A rubber compound as disclosed above, or as described above as preferred, is preferred, wherein the metal cation of the inorganic material is not a zinc cation, and preferably is not a transition metal cation at all.

[0015] A rubber compound as disclosed above, or as described above as preferred, is preferred, wherein the inorganic material replaces the metal cation. - comprises at least one alkali metal cation or at least one alkaline earth metal cation in stoichiometric amounts, preferably comprising at least one alkaline earth metal cation in stoichiometric amounts, and / or - at least one carbonate unit (CO3) 2- ) in stoichiometric amounts, preferably comprising a carbonate unit (CO3) 2- ) and a hydroxide unit (HO - ) in stoichiometric quantities.

[0016] One advantage of the aspect described above is that inorganic materials containing the aforementioned cations mix particularly well with rubber compounds. This is primarily due to the fact that the cations described above do not possess an excessively high positive charge.

[0017] Within the scope of the present invention, the expression "in stoichiometric amounts" preferably means that the stoichiometric coefficient in the chemical formula - of the respective chemical element, such as an alkali metal or alkali metal cation as described above, or - the respective formula unit, such as a carbonate unit (CO3) described above 2- ) or a hydroxide unit (HO - ), at least 0.1, particularly preferably at least 0.5, most preferably at least 1.

[0018] A rubber compound disclosed above as described above or as preferably described above is preferred, wherein the general molecular formula of the inorganic material corresponds to the following Formula I or Formula II: - A b M n · zH2O, (I) or - A b M n (OH) y ·zH2O, preferably with b = n + 2y, (II) is, whereby - A is an alkali metal cation and / or an alkaline earth metal cation, preferably an alkaline earth metal cation, - M = O -2 , CO3 -2 , SiO3 -2 or AlO3 -3 is preferred M = CO3 -2 ; - z is in the range of 0 to 20, preferably in the range of 1 to 20, particularly preferably in the range of 1 to 12, and - b, n and y are selected stoichiometrically such that the chemical unit represented in the overall formula is electrically neutral.

[0019] An advantage of the two aspects described above is that during the heating of the rubber compound in the puncture, a gas is released which reduces or prevents the rate of heating of the rubber compound in the tire, thus extending the puncture life of the tire in question. Particularly preferably, in the above formula (I) or in the above formula (II), A Ca 2+ and / or Mg 2+ ; preferably at least Mg 2+ .

[0020] In the above formula (I) the preferred one is A = Ca 2+ and / or Mg 2+ and M = CO3 -2 and n = b and z lies in the range of 0 to 20, preferably z = 0.

[0021] In the above formula (II) the preferred one is A = Mg 2+ and M = CO3 -2 and b = n + 2y and y = 2 and z lies in the range of 1 to 12, preferably in the range of 2 to 6.

[0022] A preferred rubber compound as disclosed above, or as described above as preferred, is a rubber compound as disclosed above, wherein the inorganic material exhibits an endothermic peak in a DSC (differential scanning calorimetry) measurement during the temperature rise of the DSC measurement, and the peak maximum of the endothermic peak is in the range of 250 to 350 °C, preferably in the range of 275 °C to 325 °C, particularly preferably in the range of 300 °C to 315 °C, wherein the temperature rise of the DSC measurement is preferably constant, preferably over the entire temperature range of 30 °C to 400 °C, and preferably is 10 K / min.

[0023] One advantage of the aspect described above is that hydrate water is released in the temperature range that lies between the operating temperature of a vehicle tire in normal operation and the temperature of the vehicle tire during a puncture or at which a rubber compound can ignite.

[0024] The released hydrate water is in a gaseous state at the time of its release.

[0025] Particularly preferred is a rubber compound as disclosed above, as described above or as described above as preferred, wherein - the rubber compound comprises at least 50 phr of the inorganic material, preferably at least 70 phr, particularly preferably 70 to 90 phr, and / or - the inorganic material - at least one carbonate unit (CO3) 2- ) in stoichiometric quantities and - exhibits an exothermic peak in a DSC measurement (Dynamic Differential Calorimetry) during the temperature increase of the DSC measurement, and the peak minimum of the exothermic peak is in the range of 400 to 600 °C, preferably in the range of 425 °C to 550 °C, particularly preferably in the range of 450 °C to 500 °C, wherein the temperature increase of the DSC measurement is preferably constant, preferably over the entire temperature range of 30 °C to 600 °C, and preferably is 10 K / min.

[0026] One advantage of the aspect described above is that carbon dioxide is released over a wide temperature range, and thus releases relatively little heat and is heat-resistant, especially within this temperature range. The rubber compound described above is therefore particularly well-suited for use in vehicle tires for trucks, agricultural vehicles, and special-purpose vehicles, such as military vehicles, since higher temperatures can occur in such tires during a puncture. Furthermore, the released gaseous carbon dioxide has the effect of at least temporarily increasing the tire's internal pressure. This extends the tire's service life during a puncture, especially if the inorganic material increases the airtightness of the rubber compound as described below, where the inorganic material is present in an amount of at least 30, preferably at least 90 phr.

[0027] A preferred rubber mixture as disclosed above, or as described above as preferred, is wherein the at least one rubber comprises at least one compound, preferably one, two or three compounds, selected from the group consisting of halobutyl rubber, butyl rubber, natural rubber, epoxidized natural rubber (ENR), butadiene rubber and styrene-butadiene rubber, wherein the at least one rubber preferably comprises at least halobutyl rubber.

[0028] One advantage of the aspect described above is that the types of rubber described above can be mixed particularly well with an inorganic material such as the various inorganic materials described above.

[0029] A rubber compound as disclosed above or as described above is preferred, wherein the at least one processing aid comprises one or two plasticizers selected from the group consisting of mineral oils and resins, wherein the at least one processing aid preferably comprises at least one mineral oil.

[0030] One advantage of the aspect described above is that mineral oils, due to their high temperature resistance, are particularly well suited as processing aids or plasticizers in rubber compounds. Furthermore, they are more economical, especially cost-effective.

[0031] A rubber compound as disclosed above, or as described above as preferred, is preferred, wherein the rubber compound comprises fillers, wherein the fillers comprising at least one compound selected from the group consisting of carbon black and silica, preferably carbon black, and / or

[0032] in a total quantity of 1 to 200 phr, preferably in a total quantity of 1 to 100 phr, particularly preferably in a total quantity of 1 to 60 phr.

[0033] One advantage of the aspect described above is that the processability in the mixer and in downstream processing steps, such as extrusion, is particularly advantageous with the quantities described above. Fillers, and especially reinforcing fillers such as carbon black, impart certain desired properties to a vulcanized rubber compound, which are relevant for the specific technical application of the compound.

[0034] Optionally, the sulfur-curable rubber compound disclosed above contains at least one carbon black. Within the scope of the present invention, carbon blacks are in principle all types of carbon black known in the prior art, such as carbon black N 660. Preferably, however, a carbon black is used that has an iodine adsorption number according to ASTM D 1510 of 20 to 180 g / kg, particularly preferably 30 to 140 g / kg, and a DBP number according to ASTM D 2414 of 30 to 200 ml / 100 g, preferably 90 to 180 ml / 100 g, particularly preferably 110 to 180 ml / 100 g. A particularly suitable carbon black within the scope of the present invention is, for example, a carbon black of ASTM type N339 with an iodine adsorption number of 90 g / kg and a DBP number of 120 ml / 100 g.

[0035] The rubber compound disclosed above may optionally contain at least one silica as a filler. Silicas are reinforcing fillers. The optionally included silica may be any type known in the prior art.

[0036] According to a preferred embodiment, the rubber mixture contains 0.1 to 30 phr of at least one silica, preferably 5 to 30 phr of at least one silica.

[0037] The terms “silica”, “silica” and “silika” are used synonymously within the scope of the present invention.

[0038] The silicas used can be those known in the art and suitable as fillers for tire rubber compounds. However, it is particularly preferred to use finely dispersed, precipitated silica with a nitrogen surface area (BET surface area) (according to DIN ISO 9277 and DIN 66132) of 35 to 350 m².2 / g, preferably from 35 to 260 m 2 / g, especially preferably from 70 to 235 m 2 / g and especially preferred from 70 to 205 m 2 / g, and a CTAB surface area (according to ASTM D 3765) of 30 to 400 m² 2 / g, preferably from 30 to 255 m 2 / g, especially preferably from 65 to 230 m 2 / g and especially preferred from 65 to 200 m 2 / g, exhibits.

[0039] Such silicas, for example, result in particularly good physical properties of vulcanizates in rubber compounds for inner tire components. Furthermore, advantages in compound processing can arise from a reduction in mixing time while maintaining consistent product properties, leading to improved productivity. Examples of suitable silicas include those of the Ultrasil® VN3 type (trade name) from Evonik, silicas with a comparatively low BET surface area (such as Zeosil® 1115 or Zeosil® 1085 from Solvay), and highly dispersible silicas, so-called HD silicas (e.g., Zeosil® 1165 MP from Solvay).

[0040] The optionally included silica can be in the form of bound or unbound silica.

[0041] In the event that the silica is present in the form of bound silica, the rubber compound preferably contains at least one silane coupling agent. Silane coupling agents are also referred to as "silane" within the scope of the present invention.

[0042] One or more different silane coupling agents can be used in combination. The rubber compound can therefore contain a mixture of different silanes.

[0043] The silane coupling agents react with the surface silanol groups of silica or other polar groups during the mixing of the rubber or rubber compound (in situ) or even before the addition of the filler to the rubber as a pretreatment (pre-modification). Any silane coupling agents known in the prior art for use in rubber compounds can be used as silane coupling agents. Such coupling agents known in the prior art are bifunctional organosilanes that have at least one alkoxy, cycloalkoxy, or phenoxy group as a leaving group on the silicon atom and that possess, as a further functionality, a group which, if necessary after cleavage, can undergo a chemical reaction with the double bonds of the polymer. The latter group can be, for example, the following chemical groups: -SCN, -SH, -NH2 or -S x - (with x = 2 to 8).

[0044] A rubber compound disclosed above as described above or as preferably described above is preferred, wherein the inorganic material is in the form of particles and at least 10 wt.%, preferably at least 50 wt.%, of these particles of the inorganic material have a ratio of particle length to particle width in the range of 1.0 to 10, preferably in the range of 1.0 to 5, particularly preferably in the range of 1.0 to 2.8.

[0045] One advantage of the aspect described above is that, due to the conditions described above, the particles described above have a particularly large surface area and can therefore absorb more heat in a shorter period of time. Furthermore, the particle length-to-width ratios described above increase the airtightness of a rubber compound disclosed above. Both of these factors result in a longer lifespan for the vehicle tire with a rubber compound disclosed above.

[0046] A preferred rubber compound is one as disclosed above, as described above, or as preferably described above, wherein the inorganic material is in the form of particles and the average particle size of the total quantity of particles or the size of at least 95% of the particles of the inorganic material is in the range of 0.1 µm to 1 mm, particularly preferably in the range of 1 µm to 0.5 mm, most preferably in the range of 10 µm to 0.2 mm, and most preferably in the range of 40 µm to 100 µm. The determination of the average particle size or the size of at least 95% of the particles should preferably be carried out by laser diffraction.

[0047] One advantage of the aspect described above is that, due to the conditions described above, the particles described above have a particularly large surface area and can therefore absorb more heat in a shorter period of time. Furthermore, the particle sizes described above also increase the airtightness of a rubber compound disclosed above. Both of these factors lead to a longer service life of the vehicle tire with a rubber compound disclosed above.

[0048] Within the scope of the present invention, the inorganic material of a rubber material mixture as disclosed above is preferably in the form of a free-flowing powder.

[0049] A rubber compound as disclosed above, or as described above as preferred, is preferred, wherein the rubber compound has a thermal conductivity of at least 0.25 W / (m·K), preferably at least 0.3 W / (m·K).

[0050] One advantage of the aspect described above is that, due to its thermal conductivity, the rubber compound described above can dissipate heat more quickly, and therefore such a preferred rubber compound heats up less than a rubber compound containing a different inorganic material. This results in a longer service life for the vehicle tire with a rubber compound as disclosed above.

[0051] A rubber compound disclosed above as described above or as preferably described above is preferred, wherein the inorganic material releases at least 1 wt.% or at least 5 wt.% water, preferably water of hydration, when heated in the range of 100 °C to 300 °C, based on the total amount of the inorganic material before heating, preferably the heating is carried out at 10 K / min.

[0052] The advantage of the aspect described above has already been described above.

[0053] A preferred rubber compound as disclosed above, or as described above as preferred, is presently wherein the inorganic material releases carbon dioxide upon heating in the range of 100 °C to 500 °C, preferably at least 5 wt.% carbon dioxide, and particularly preferably at least 20 wt.% carbon dioxide, in each case based on the total amount of the inorganic material before heating. Preferably, the heating is carried out at 10 K / min, and the release of the 5 wt.% or 20 wt.% carbon dioxide relates only to the range of 300 °C to 500 °C.

[0054] The advantage of the aspect described above has already been described above.

[0055] A rubber compound as disclosed above, or as described above as preferred, is preferred, wherein the rubber compound - Stearic acid, preferably in an amount of 0.1 to 8 phr, and / or - ZnO, preferably in an amount of 0.1 to 8 phr.

[0056] ZnO is a component of the crosslinking system. This is particularly true for halobutyl rubber. Stearic acid influences the crosslinking rate by adjusting the mixture to a preferred pH value. The quantities described above optimize the processability for the extrusion line and vulcanization process used, and in particular, prevent unwanted pre-vulcanization, also known as scorch. Stearic acid can also optimize the processing of extruded components by influencing their tackiness.

[0057] A rubber mixture disclosed above as described above or as preferably described above is preferred, wherein the inorganic material comprises at least one compound selected from the group consisting of carbonates, hydroxides and mixtures thereof, preferably the inorganic material consists of one compound or of both compounds selected from the group consisting of carbonates and hydroxides.

[0058] Particularly preferred is a rubber mixture as disclosed above, as described above or as preferably described above, wherein the inorganic material comprises at least one compound or at least two compounds selected from the group consisting of huntite, hydromagnesite, calcium carbonate, magnesium hydroxide and aluminum hydroxide; most preferably, the inorganic material comprises one compound or both compounds selected from the group consisting of huntite and hydromagnesite.

[0059] One advantage of the aspect described above is that these materials are particularly well suited for use in rubber compounds. Huntite advantageously comprises four carbonate units (CO3). 2- ) in its chemical formula. Hydromagnesite advantageously comprises four carbonate units (CO3). 2- ) and two hydroxide units (HO - ) in its chemical formula.

[0060] A rubber compound disclosed above as described above or as described above as preferred is preferred, wherein the inorganic material is present in an amount of at least 30 phr, preferably in an amount of at least 70 phr, and particularly preferred if an amount of 70 phr to 90 phr is present.

[0061] One advantage of the aspect described above is that the rubber compounds described above, with a minimum of 70 phr of inorganic material, exhibit particularly good airtightness. This has the benefit that the gases released during heating, such as water or carbon dioxide, as described above, can be retained in the vehicle's pneumatic tires for as long as possible during a puncture. Furthermore, this reduces the rate of temperature rise and / or the maximum temperature reached by the rubber compound during a puncture.

[0062] A rubber compound disclosed above as described above or as described above as preferred is preferred, wherein the inorganic material is present in an amount of not more than 90 phr or in an amount of 30 to 90 phr, preferably in an amount of 70 to 90 phr or in an amount of 30 to 50 phr.

[0063] One advantage of the aspect described above is that the rubber compound described above has several of the advantages described above.

[0064] A rubber compound as disclosed above, or as described above as preferred, is preferred, wherein the rubber compound is suitable for manufacturing an inner liner or a support element of a vehicle pneumatic tire. This has the advantages described below.

[0065] Particularly preferred is a rubber compound as disclosed above, as described above, for the manufacture of a component of a vehicle pneumatic tire, comprising: - 100 phr of at least one type of rubber, - 1 to 20 phr of at least one processing aid, - 1 to 10 phr of at least one vulcanizing agent and - 70 to 90 phr of at least one inorganic material, wherein - the inorganic material contains at least one alkaline earth metal cation in stoichiometric amounts and at least one carbonate unit (CO3). 2- ) in stoichiometric quantities, - one of which is at least one type of rubber, halobutyl rubber, - the processing aids include mineral oils, - the fillers include carbon black in a total quantity of 1 to 200 phr, - the inorganic material releases at least 5 wt.% water of hydration when heated in the range of 100 °C to 300 °C and releases at least 10 wt.% carbon dioxide when heated in the range of 300 °C to 500 °C, in each case based on the total amount of the inorganic material before heating and - the rubber mixture comprises stearic acid in an amount of 0.1 to 8 phr and ZnO in an amount of 0.1 to 8 phr.

[0066] Particularly preferred is a rubber compound as disclosed above, as described above, for the manufacture of a component of a vehicle pneumatic tire, comprising: - 100 phr of at least one type of rubber, - 1 to 20 phr of at least one processing aid, - 1 to 10 phr of at least one vulcanizing agent and - 30 to 90 phr of at least one inorganic material, where - the inorganic material contains at least one alkaline earth metal cation in stoichiometric amounts and at least one carbonate unit (CO3). 2- ) in stoichiometric quantities, - one of which is at least one type of rubber, halobutyl rubber, - the processing aids include mineral oils, - the fillers include carbon black in a total quantity of 1 to 200 phr, - the rubber compound has a thermal conductivity of at least 0.25 W / (m·K) and - the rubber mixture comprises stearic acid in an amount of 0.1 to 8 phr and ZnO in an amount of 0.1 to 8 phr.

[0067] The advantageous aspects of a rubber compound disclosed above, as described above, also apply to all aspects of vehicle pneumatic tires described below, and the advantageous aspects of disclosed vehicle pneumatic tires discussed below apply accordingly to all aspects of a rubber compound disclosed above.

[0068] Disclosure also includes a vehicle pneumatic tire comprising a rubber compound as described above or as preferably described above. A preferred vehicle pneumatic tire is one as disclosed above, wherein the vehicle pneumatic tire comprises an inner liner and the inner liner comprises the rubber compound as described above or as preferably described above.

[0069] A preferred vehicle pneumatic tire is one as described above, or as described above as preferred, wherein the vehicle pneumatic tire has at least one integrated support element, the integrated support element preferably being a reinforced sidewall. Vehicle pneumatic tires described above include, for example, SSR tires from Continental. These support elements can be made of rubber or a thermoplastic material. Additional reinforcing elements made of metal, such as steel wires or steel cords, are also possible within the integrated support elements. Rubber support elements are particularly preferred. These support elements are located between the inner layer and the reinforcing layers of the carcass.

[0070] In particular, the pneumatic tires described above as preferred, which are equipped with support elements integrated into the tire, are damaged relatively quickly during a puncture. The support element can only bear the load during a puncture for a limited period and is subject to particularly high friction, especially towards the end of this period. During this time, it is thermally damaged and eventually deteriorates. The pneumatic tires running on integrated support elements during a puncture are thermally damaged especially because the friction of the inner liner of the pneumatic tire against the support element generates heat. It is therefore particularly advantageous to incorporate a rubber compound as disclosed above into a pneumatic tire with an integrated support element.

[0071] The advantageous aspects of a rubber compound and a vehicle pneumatic tire as disclosed above, as described above, also apply to all aspects of the uses described below, and the advantageous aspects of disclosed uses discussed below apply accordingly to all aspects of a rubber compound and a vehicle pneumatic tire as disclosed above.

[0072] The use of a rubber compound as disclosed above, as described above or as preferably described above, for the manufacture of a component – ​​a tire, preferably an inner liner of a vehicle pneumatic tire – is also disclosed. - a component of a belt, - a component of a belt - a component of a hose or - a component of an air spring.

[0073] Disclosure also includes the use of an inorganic material as described above or as preferably described above for reducing the heat release of a rubber compound or component as described above or as preferably described above.

[0074] In the present invention, heat release is preferably carried out according to the standard DIN EN 45545-2 using 25 kW / m². 2 Irradiation was determined. The benchmark for quantifying heat release is the MAHRE value determined in the standard.

[0075] The use of an inorganic material as described above or as preferably described above for increasing the stiffness of the rubber compound is also disclosed, preferably for increasing the stiffness of the rubber compound at a temperature of up to 220 °C, particularly preferably for increasing the stiffness of the rubber compound at a temperature in the temperature range of 100 °C to 220 °C.

[0076] Due to its higher stiffness at elevated temperatures, a rubber compound as disclosed above can therefore be used for a longer period in the puncture test of a vehicle pneumatic tire.

[0077] The present invention will now be described with reference to several experimental examples and figures. Experimental examples: Sample preparation by vulcanization:

[0078] The compound was prepared according to standard rubber industry procedures under normal conditions in two stages using a laboratory mixer with a volume of 300 milliliters to 3 liters. In the first stage, the base mix, all components except the vulcanization system (i.e., sulfur and vulcanization-influencing substances) were mixed for 200 to 600 seconds at 145 to 175 °C, with target temperatures of 152 to 167 °C. The final compound was then produced by adding the vulcanization system in the second stage, the finishing mix, which was mixed for 180 to 300 seconds at 90 to 120 °C.

[0079] Test specimens were produced from all mixtures by vulcanization at 160°C and material properties typical for the rubber industry were determined using these test specimens and the test procedures specified below. Measurement methods:

[0080] General remarks: The test specimens that may be used for one of the measurement methods described below were produced using a rubber composition according to Table 1 as described below. 1. Measurement of airtightness

[0081] The results were determined in accordance with the method according to DIN 53 536 at an air temperature of 70 °C. 2. Thermal conductivity

[0082] The results were determined in accordance with the DIN 52612 method. 3. Dynamic stiffness measurement

[0083] The results were determined in accordance with the DIN 53513 method. 4. TGA measurement

[0084] The results were obtained using a Netzsch TG 209F1 Libra TGA instrument. The heating program was as follows: 35°C to 800°C with a ramp rate of 10 K / min. 18.8 mg of sample consisting of a mixture of huntite and hydromagnesite was placed in a ceramic crucible. The ambient gas used in the TGA measurement was nitrogen (N2). 5. DSC measurement

[0085] The results were obtained using a DSC 204 F1 Phoenix instrument from Netzsch. The heating program was as follows: 30°C to 550°C with a ramp rate of 10 K / min. 3.6 mg of sample were placed in a ceramic crucible. The ambient gas used in the DSC measurement was N2. Results: Table 1: Experimental data of the rubber compound produced according to the invention and not according to the invention ingredient Crowd MS Cf.-Exp.V1 Exp.E1 Exp.E2 Exp.E3 Exp.E4 Non-inventive inventive Inventive Inventive Inventive Butyl rubber CIIR, medium viscosity phr 1 100 100 100 100 100 Soot (N 660) phr 1 55 55 55 55 55 Total amount of huntite and hydromagnesite phr 1 0 30 50 70 90 mineral oil phr 1 8 8 8 8 8 ZnO phr 1 3 3 3 3 3 Stearic acid phr 1 2 2 2 2 2 Plasticizers phr 1 16 16 16 16 16 sulfur phr 2 0,4 0,4 0,4 0,4 0,4 Vulcanization accelerator phr 2 1 1 1 1 1 Note Table 1: MS stands for mixing stage Table 2: Experimental data of the rubber compound produced according to the invention and not according to the invention Characteristic Unit Comparison Experiment V1 Exp. E1 Exp. E2 Exp. E3 Not inventive. Inventive Inventive Inventive Airtightness % 100 103 108 94 specific thermal conductivity W / (m · K) 0,23 0,26 0,28 0,3 Explanations regarding airtightness testing:

[0086] In the airtightness measurement described above, the various measured values ​​of the rubber compounds from experiments V1, E1, E2, and E3 were determined and normalized as shown in Table 2 in comparison to the reference experiment V1. It should be noted that in this measurement, higher values ​​indicate poorer airtightness and lower values ​​indicate better airtightness. Therefore, it can be concluded from Table 2 that rubber compounds with an inorganic material content of more than 70 phr, such as that from experiment E3, exhibit improved airtightness compared to the rubber compound from reference experiment V1 with 0 phr of inorganic material. Explanations regarding thermal conductivity measurement:

[0087] In the thermal conductivity measurement described above, the different specific thermal conductivities of the rubber compounds from experiments V1, E1, E2, and E3 were determined. Table 2 therefore shows that rubber compounds with an inorganic material content of more than 30 phr exhibit improved thermal conductivity compared to the rubber compound from the reference experiment V1, which contained 0 phr of inorganic material. This leads to the advantages described above, as heat can be dissipated more quickly. Character description:

[0088] It shows: Fig. 1: The results of a TGA measurement of an inorganic material of a rubber compound according to the invention; Fig. 2: The results of a DSC measurement of an inorganic material of a rubber compound according to the invention; Fig.3: The results of a measurement of the dynamic stiffness of a vulcanized rubber compound according to the invention. Explanations for Figure 1, TGA measurement:

[0089] In Fig. Figure 1 shows the results of the TGA measurement, in which a mixture of huntite and hydromagnesite, as an example of an inorganic material in a rubber compound according to the invention, was heated. The x-axis shows the temperature in degrees Celsius and the y-axis the respective mass loss, with the initial weight of the sample normalized to 100%. The ambient gas during the TGA measurement was nitrogen up to 550°C and subsequently oxygen, and the measurement was performed at a gas flow rate of 20 milliliters per minute.

[0090] In Fig. 1 Four offsets O1, O2, O3 and O4 can be seen, each of which has led to a corresponding mass change dm 1, dm 2, dm 3 and dm 4.

[0091] The first O1 offset occurred around 261 °C and resulted in a mass change dm 1 of approximately 8%. Due to this 8% mass reduction and the strongly endothermic peak at 311 °C, as in Fig. As shown in Figure 2 (DSC measurement), the first offset O1 can be attributed to the loss of hydration water.

[0092] The second O2 offset occurred around 400 °C and resulted in a mass change (dm²) of approximately 27.4%. Due to this mass reduction of 27.4% and the slightly endothermic peak at 432 °C, as in Fig. As shown in 2 (DSC measurement), the second offset O2 can be attributed to the decomposition of the carbonate. Explanations for Figure 2, DSC measurement:

[0093] In Fig. Figure 2 shows the graphical representation of the DSC measurement result, with the temperature of each measurement point on the x-axis. The graph of the DSC measurement in Fig.Figure 2 has two y-axes, with the right y-axis representing the gas flow rate, which was constant at 20 milliliters per minute. The gas used in this case was nitrogen. The left y-axis shows the energy released or absorbed from the sample during heating. It is important to note that exothermic reactions are indicated by a negative peak, as shown next to the left y-axis. The graph in Fig. The DSC curve shown in Figure 2 has three peaks, P1, P2 and P3, where peaks P1 and P2 represent endothermic peaks and peak P3 represents an exothermic peak.

[0094] As described above, peak P1 at 311 °C can be attributed to the loss of hydration water from the sample, since peak P1 is strongly exothermic and the first O1 offset around 261 °C resulted in a mass change dm1 of approximately 8%. As described above, peak P2 at 432 °C can be attributed to the decomposition of the carbonate in the sample, since peak P2 is only slightly exothermic and the second O2 offset around 400 °C resulted in a mass change dm2 of approximately 27.4%. Explanations for Figure 3, Measurement of the dynamic stiffness of a vulcanized rubber compound according to the invention:

[0095] In Fig.Figure 3 shows the results of the stiffness measurement graphically. The x-axis again indicates the temperature of the respective measurement points. The y-axis shows the modulus E' in MPa on a logarithmic scale. Dynamic stiffness is quantified using the modulus E', as this modulus is relevant to the stiffness of the compound during punctures. A high value is desirable to support the tire during punctures. As the tire deteriorates, the temperature rises, and the cooling effect from the release of water vapor or other materials begins at higher temperatures.

[0096] The vulcanized rubber mixtures according to the invention decompose after the release of water and the dynamic modulus E' of the comparison mixture and the rubber mixtures E1 to E4 according to the invention decrease.

[0097] In Fig.Figure 3 clearly shows that all the rubber compounds according to the invention in experiments E1, E2, E3, and E4 are stiffer than the rubber compound in the comparison experiment V1. This is particularly advantageous for temperatures above 150 °C, which are frequently reached in the rubber compound during the puncture test of a vehicle tire. Due to the higher stiffness at elevated temperatures, the rubber compound can therefore be used for a longer period in the puncture test of a vehicle tire according to the invention. Reference symbol list: G Gas flow rate on the second y-axis O1 first onset of the TGA measurement O2 second onset of the TGA measurement O3 third onset of the TGA measurement O4 fourth onset of the TGA measurement dm1 Mass difference of the first onset of the TGA measurement dm² Mass difference of the second onset of the TGA measurement dm3 Mass difference of the third onset of the TGA measurement dm4 Mass difference of the fourth onset of the TGA measurement P1 Peak maximum of the endothermic first peak of the DSC measurement P2 peak maximum of the endothermic second peak of the DSC measurement P3 Peak minimum of the exothermic third peak of the DSC measurement

Claims

[1] Sulfur-curable rubber compound, preferably for the manufacture of a component of a vehicle pneumatic tire, comprising: - 100 phr of at least one type of rubber, - at least one processing aid, - at least one vulcanizing agent - Stearic acid and - 1 to 200 phr of at least one inorganic material, wherein the inorganic material comprises at least one metal cation, wherein the inorganic material consists of at least one compound selected from the group consisting of huntite and hydromagnesite. [2] Rubber compound according to claim 1, wherein the inorganic material has an endothermic peak (P1) in a DSC (differential scanning calorimetry) measurement during the temperature rise of the DSC measurement and the peak maximum of the endothermic peak (P1) is in the range of 250 to 350 °C, preferably in the range of 275 °C to 325 °C, particularly preferably in the range of 300 °C to 315 °C, wherein preferably the temperature rise of the DSC measurement is constant and is 10 K / min. [3] Rubber compound according to any of the preceding claims, wherein the at least one rubber comprises at least one compound selected from the group consisting of halobutyl rubber, butyl rubber, natural rubber, epoxidized natural rubber, butadiene rubber and styrene-butadiene rubber, wherein the at least one rubber preferably comprises at least butyl rubber. [4] Rubber compound according to any of the preceding claims, wherein the at least one processing aid comprises one or two plasticizers selected from the group consisting of mineral oils and resins, wherein the at least one processing aid preferably comprises at least one mineral oil. [5] Rubber compound according to any of the preceding claims, wherein the rubber compound comprises fillers, the fillers comprising at least one compound selected from the group consisting of carbon black and silica, preferably carbon black, and / or being present in a total amount of 1 to 200 phr. [6] Rubber compound according to any of the preceding claims, wherein the inorganic material is in the form of particles and - at least 10 wt.%, preferably at least 50 wt.%, of these particles of the inorganic material have a particle length to particle width ratio in the range of 1.0 to 2.8 and / or - the average particle size of the total quantity of particles or the size of at least 95% of the particles of the inorganic material is in the range of 0.1 µm to 1 mm, particularly preferably in the range of 1 µm to 0.5 mm, most preferably in the range of 10 µm to 0.2 mm, and most preferably in the range of 40 µm to 100 µm. [7] Rubber compound according to any one of the preceding claims, wherein - the rubber compound has a thermal conductivity of at least 0.25 W / (m·K), preferably at least 0.3 W / (m·K), - the inorganic material releases at least 1 wt.% or at least 5 wt.% water, preferably water of hydration, when heated in the range of 100 °C to 300 °C, based on the total amount of the inorganic material before heating, preferably the heating is carried out at 10 K / min, and / or - the inorganic material releases carbon dioxide when heated in the range of 100 °C to 500 °C, preferably at least 5 wt.% carbon dioxide, particularly preferably at least 20 wt.% carbon dioxide, in each case based on the total amount of the inorganic material before heating. [8] Rubber compound according to any of the preceding claims, wherein the inorganic material is present in an amount of at least 30 phr, preferably in an amount of at least 70 phr, and particularly preferably in an amount of 70 phr to 90 phr. [9] Vehicle pneumatic tire comprising a rubber compound according to any of the preceding claims. [10] Vehicle pneumatic tire according to claim 9, wherein the vehicle pneumatic tire comprises an inner liner and the inner liner comprises the rubber compound according to any one of claims 1 to 8. [11] Use of a rubber compound according to any one of claims 1 to 8 for the manufacture of a component of a tire, a component of a belt, a component of a strap or a component of a tube, preferably an inner liner of a vehicle pneumatic tire. [12] Use of an inorganic material as defined in any one of claims 1 to 8 - to reduce heat release during the heating of a rubber compound or component as defined in the preceding claim 11 and / or - to increase the stiffness of the rubber compound.

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