Sulfur-crosslinkable rubber compound, vulcanizate and vehicle tire

Description

[0001] The invention relates to a sulfur-crosslinkable rubber mixture, a vulcanizate and a vehicle tire.

[0002] The rubber composition of the tread largely determines the driving characteristics of a tire, especially a pneumatic vehicle tire. Likewise, the rubber compounds used in belts, hoses, and straps, especially in areas subject to high mechanical stress, are largely responsible for the stability and durability of these rubber products. Therefore, very stringent requirements are placed on these rubber compounds for pneumatic vehicle tires, belts, and hoses.

[0003] For example, by partially or completely replacing the carbon black filler with silica in rubber compounds, the driving characteristics of a tire have been brought to a higher level in recent years. However, the well-known conflicting objectives of opposing tire properties still exist even with tread compounds containing silica. For example, an improvement in rolling resistance generally still results in a deterioration in abrasion behavior. These properties are also an important quality criterion for technical rubber products such as belts, straps, and hoses.

[0004] A variety of approaches have been pursued to resolve these conflicting objectives. For example, a wide variety of polymers, including modified ones, plasticizers, and highly dispersed fillers have been used in rubber compounds, and attempts have been made to influence the vulcanizate properties by modifying the compounding process.

[0005] Organosilanes are used in silicic acid-containing rubber compounds to make the silica hydrophobic and thereby create the bond between the filler and the polymer. For this to happen, the silica must be well distributed within the rubber compound, i.e., it must be readily dispersible. Silicas, in particular, which have a relatively high specific surface area, are known to be very difficult to disperse in rubber compounds. Polysulfidic organosilanes are bound to the polymer. However, different silanes have different effects on the physical properties of the rubber compound. For example, it is known from WO2008083242A1 that the silanes with cyclic units described therein, so-called "silated core polysulfides" (SCP), improve abrasion behavior but have no effect on rolling resistance behavior.Compared to conventional multimeric sulfur silanes, such as bis(triethoxysilylpropyl) disulfide (TESPD) and bis(triethoxysilylpropyl) tetrasulfide (TESPT), monomeric silanes, such as mercaptosilanes, do improve rolling resistance behavior, but are associated with significantly impaired processability, reduced wet grip behavior, and greater abrasion loss. Protected mercaptosilanes, i.e. mercaptosilanes in which the mercapto group is blocked, only slightly improve rolling resistance at the expense of wet grip and abrasion, although stiffness, i.e. handling potential, is reduced. The use of a silica-silane system in compounds containing natural rubber as the sole polymer or as the main polymer component, i.e. a proportion of more than 50 phr, is limited due to high abrasion losses and lower reinforcement compared to compounds with carbon black as the sole or main filler.US Pat. No. 7,625,965 B2 describes a rubber compound with 100 phr of natural rubber, which contains more than 50 phr of silica and an alkoxysilane with a benzyl chloride unit. However, it is shown that even such a silane still exhibits weaknesses in terms of rolling resistance behavior in rubber compounds with more than 50 phr of silica and 3 phr of carbon black.

[0006] JP 2012-158679 A discloses a rubber mixture comprising a silane of the general formula (R 1< R 2< R 3< Si-) m X n (-R 4< -Y) r .

[0007] JP 2011-225730 A discloses a rubber mixture comprising an organic silane of the general formula R 1< R 2< R 3< Si-R 4< -R 5< -CR 6< (3-m) -X m .

[0008] US 7 625 965 B2 discloses a rubber mixture comprising a silane of the general formula [X 1< X 2< X 3< Si-] d (G) a [-Y-(CR 3-e -Z e ) b ] c .

[0009] US 2010 / 036018 A1 discloses a rubber mixture comprising a halogen-containing aralkylsilane of the general formula X 1< X 2< X 3< Si-C(R 1< ) 2-a (Z 1< a )-G-(CR 3-c -Z 2< c ) b .

[0010] The invention is therefore based on the object of providing a silicic acid-containing rubber mixture which improves the level of properties, in particular including rolling resistance behavior, abrasion and reinforcing effect, while the other physical properties remain at approximately the same level.

[0011] The object is achieved according to the invention by the sulfur-crosslinkable rubber mixture according to claim 1.

[0012] Surprisingly, it was found that such a rubber compound has an improved level of properties and, in particular, shows improved rolling resistance behavior and, in particular, an optimized reinforcing effect, without negatively affecting the other physical properties.

[0013] A further subject of the present invention is a vulcanizate of at least one rubber mixture according to the invention.

[0014] The present invention further provides a vehicle tire comprising at least one vulcanizate of the rubber mixture according to the invention in at least one component. Preferably, the vehicle tire comprises the at least one vulcanizate at least in the tread.

[0015] The vulcanizate and the vehicle tire according to the invention are characterized by improved rolling resistance. At the same time, they exhibit excellent handling and a very good level of abrasion.

[0016] In the case of two-part treads (upper part: cap and lower part: base), the rubber mixture according to the invention can be used for both the cap and the base. Preferably, at least the cap or at least the base, or at least the cap and the base, comprise at least one vulcanizate of the rubber mixture according to the invention.

[0017] The rubber mixture according to the invention is also suitable for treads consisting of different tread mixtures arranged next to one another and / or one below the other (multi-component treads).

[0018] For the purposes of the present invention, vehicle tires are understood to mean pneumatic vehicle tires and solid rubber tires, including tires for industrial and construction vehicles, truck, car and two-wheel tires.

[0019] The rubber mixture according to the invention is also suitable for other components of vehicle tires, such as, in particular, the horn profile, as well as for inner tire components.

[0020] The rubber mixture according to the invention is also suitable for other technical rubber articles, such as bellows, conveyor belts, air springs, belts, straps or hoses, as well as shoe soles.

[0021] A further object of the present invention is the use of the rubber mixture according to the invention for producing a rubber article, in particular an air spring, a bellows, conveyor belt, strap, belt, hose, rubber band, profile, a seal, a membrane, tactile sensors for medical applications or robot applications, or a shoe sole or parts thereof.

[0022] The components of the sulfur-crosslinkable rubber mixture according to the invention are described in more detail below. All statements also apply to the vulcanizate according to the invention and the vehicle tire according to the invention, which comprises at least one vulcanizate according to the invention of the rubber mixture according to the invention in at least one component.

[0023] The term phr (parts per hundred parts of rubber by weight) used in this document is the quantity commonly used in the rubber industry for compound formulations. The dosage of the parts by weight of the individual substances in this document is based on 100 parts by weight of the total mass of all rubbers present in the mixture with a molecular weight M w according to GPC of greater than 20,000 g / mol. The term phf (parts per hundred parts of filler by weight) used in this document is the quantity commonly used in the rubber industry for

[0024] Coupling agents for fillers. In the context of this application, phf refers to the silica present, meaning that other fillers that may be present, such as carbon black, are not included in the calculation of the silane quantity.

[0025] According to the invention, the rubber mixture is sulfur-crosslinkable and contains at least one diene rubber for this purpose.

[0026] 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.

[0027] The diene rubber is preferably selected from the group consisting of natural polyisoprene and / or synthetic polyisoprene and / or epoxidized polyisoprene and / or butadiene rubber and / or butadiene-isoprene rubber and / or solution-polymerized styrene-butadiene rubber and / or emulsion-polymerized styrene-butadiene rubber and / or styrene-isoprene rubber and / or liquid rubbers with a molecular weight M w of greater than 20,000 g / mol and / or halobutyl rubber and / or polynorbornene and / or isoprene-isobutylene copolymer and / or ethylene-propylene-diene rubber and / or nitrile rubber and / or chloroprene rubber and / or acrylate rubber and / or Fluororubber and / or silicone rubber and / or polysulfide rubber and / or epichlorohydrin rubber and / or styrene-isoprene-butadiene terpolymer and / or hydrogenated acrylonitrile butadiene rubber and / or hydrogenated styrene-butadiene rubber.

[0028] In particular, nitrile rubber, hydrogenated acrylonitrile-butadiene rubber, chloroprene rubber, butyl rubber, halobutyl rubber, or ethylene-propylene-diene rubber are used in the production of technical rubber articles, such as belts, straps, and hoses, and / or shoe soles. The blend compositions known to those skilled in the art for these rubbers—specific with regard to fillers, plasticizers, vulcanization systems, and additives—are preferred.

[0029] The rubber compound is particularly suitable for vehicle tires, although it can in principle be used in any component, such as the tread, the sidewall, the horn profile, as well as in other so-called body components.

[0030] Preferably, the diene rubber is selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), solution-polymerized styrene-butadiene rubber (SSBR), emulsion-polymerized styrene-butadiene rubber (ESBR), butyl rubber (IIR), and halobutyl rubber.

[0031] According to a particularly preferred embodiment of the invention, the diene rubber is 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). Such a rubber mixture is particularly suitable for the tread of vehicle tires.

[0032] According to a particularly advantageous embodiment of the invention, the rubber mixture contains at least one natural polyisoprene, preferably in amounts of 2 to 100 phr, and according to a particularly advantageous embodiment of the invention, 70 to 100 phr. This achieves particularly good processability of the rubber mixture according to the invention and optimized tear properties.

[0033] According to a particularly advantageous embodiment of the invention, the rubber mixture contains at least one polybutadiene (butadiene rubber), preferably in amounts of 2 to 100 phr, and according to a particularly advantageous embodiment of the invention, 5 to 50 phr, most preferably 10 to 25 phr. This achieves particularly good abrasion and tear properties and good processability with low hysteresis loss of the rubber mixture according to the invention.

[0034] According to a particularly advantageous embodiment of the invention, the rubber mixture contains at least one styrene-butadiene rubber (SBR), preferably in amounts of 2 to 100 phr, and according to a particularly advantageous embodiment of the invention, 25 to 90 phr, most preferably 65 to 90 phr. This results in good processability with low hysteresis loss and good abrasion and tear properties of the rubber mixture according to the invention. The SBR is preferably an SSBR, which results in optimized hysteresis properties.

[0035] According to a particularly advantageous embodiment of the invention, the rubber mixture contains a polymer blend of two or more of the aforementioned rubbers NR, BR and SBR, preferably SSBR, in all conceivable combinations, the sum of all rubbers contained being 100 phr.

[0036] The natural and / or synthetic polyisoprene in all embodiments can be either cis-1,4-polyisoprene or 3,4-polyisoprene. Polyisoprene can be obtained by stereospecific polymerization in solution with Ziegler-Natta catalysts or using finely divided lithium alkyls. However, the use of cis-1,4-polyisoprenes with a cis-1,4 content of > 90 wt.% is preferred. Natural rubber (NR) is such a cis-1,4-polyisoprene, with the cis-1,4 content in the natural rubber being greater than 99 wt.%. Furthermore, a mixture of one or more natural polyisoprenes with one or more synthetic polyisoprene(s) is also conceivable.

[0037] For the purposes of the present invention, the term "natural rubber" refers to naturally occurring rubber that can be obtained from Hevea rubber trees and non-Hevea sources. Non-Hevea sources include, for example, guayule shrubs and dandelions such as TKS (Taraxacum kok-saghyz; Russian dandelion).

[0038] If the rubber mixture according to the invention contains butadiene rubber (= BR, polybutadiene), it can be any type known to the person skilled in the art.

[0039] These include the so-called high-cis and low-cis types, with polybutadiene with a cis content greater than or equal to 90% being referred to as high-cis, and polybutadiene with a cis content less than 90% being referred to as low-cis. An example of a low-cis polybutadiene is Li-BR (lithium-catalyzed butadiene rubber) with a cis content of 20 to 50%. High-cis BR achieves particularly good abrasion properties and low hysteresis of the rubber compound.

[0040] The polybutadiene(s) used can be end-group modified and / or functionalized along the polymer chains. The modifications can include hydroxyl groups, ethoxy groups, epoxy groups, siloxane groups, amino groups, aminosiloxane, carboxyl groups, phthalocyanine groups, and / or silane sulfide groups. However, other modifications known to the skilled person, also referred to as functionalizations, are also possible. Metal atoms can be a component of such functionalizations.

[0041] If at least one styrene-butadiene rubber (styrene-butadiene copolymer) is present in the rubber mixture, it can be either solution-polymerized styrene-butadiene rubber (SSBR) or emulsion-polymerized styrene-butadiene rubber (ESBR), although a mixture of at least one SSBR and at least one ESBR can also be used. The terms "styrene-butadiene rubber" and "styrene-butadiene copolymer" are used synonymously within the scope of the present invention. The styrene-butadiene copolymer used can be end-group modified with the modifications and functionalizations mentioned above for polybutadiene and / or functionalized along the polymer chains.

[0042] According to the invention, the rubber mixture contains 5 to 500 phr of at least one silica.

[0043] The silica can be the types of silica known to the person skilled in the art that are suitable as fillers for tire rubber compounds. However, it is particularly preferred to use a finely divided, precipitated silica which has a nitrogen surface area (BET surface area) (according to DIN ISO 9277 and DIN 66132) of 35 to 400 m² / g, preferably of 35 to 350 m² / g, particularly preferably of 85 to 320 m² / g and very particularly preferably of 120 to 235 m² / g, and a CTAB surface area (according to ASTM D 3765) of 30 to 400 m² / g, preferably of 30 to 330 m² / g, particularly preferably of 80 to 300 m² / g and very particularly preferably of 115 to 200 m² / g. Such silicas lead, for example, to particularly good physical properties of the vulcanizates in rubber mixtures for tire treads.Furthermore, this can result in advantages in compound processing due to a reduction in mixing time while maintaining consistent product properties, leading to improved productivity. Silicas that can be used include, for example, Ultrasil®< VN3 (trade name) from Evonik as well as highly dispersible silicas, so-called HD silicas (e.g., Zeosil®< 1165 MP from Solvay).

[0044] According to a preferred embodiment of the invention, the rubber mixture according to the invention contains 5 to 400 phr, preferably 5 to 300 phr, of at least one silica.

[0045] According to a preferred embodiment, the rubber mixture contains 10 to 200 phr and very particularly preferably 20 to 180 phr, again preferably 20 to 100 phr, of at least one silica.

[0046] In the event that at least two different silicas, which differ, for example, in their BET surface area, are contained in the rubber mixture according to the invention, the stated quantities always refer to the total amount of all silicas contained.

[0047] The terms "silicic acid" and "silica" are used synonymously in the present invention.

[0048] The rubber mixture according to the invention contains 5 to 150 phr of at least one carbon black, in particular at least one industrial carbon black.

[0049] Suitable carbon blacks include all types of carbon black known to the person skilled in the art. In one embodiment, the carbon black has an iodine number according to ASTM D 1510, also referred to as the iodine adsorption number, between 30 and 250 g / kg, preferably 30 to 180 g / kg, more preferably 40 to 180 g / kg, and most preferably 40 to 130 g / kg, and a DBP number according to ASTM D 2414 of 30 to 200 ml / 100 g, preferably 70 to 200 ml / 100 g, more preferably 90 to 200 ml / 100 g.

[0050] The DBP number according to ASTM D 2414 determines the specific absorption volume of a carbon black or a light filler using dibutyl phthalate.

[0051] The use of such a type of carbon black in the rubber compound, especially for vehicle tires, ensures the best possible compromise between abrasion resistance and heat buildup, which in turn influences the ecologically relevant rolling resistance. It is preferred that only one type of carbon black be used in the respective rubber compound, but different types of carbon black can also be mixed into the rubber compound.

[0052] According to particularly advantageous embodiments of the invention, the weight ratio of the amount of silica to the amount of carbon black is 17:1 to 1:20.

[0053] According to an advantageous embodiment of the invention, the rubber mixture contains 5 to 20 phr of at least one carbon black and 10 to 100 phr, preferably 20 to 100 phr of at least one silica.

[0054] The rubber mixture according to the invention may contain further fillers, for example in amounts of 0.1 to 50 phr. Other (non-reinforcing) fillers within the scope of the present invention include aluminosilicates, kaolin, chalk, starch, magnesium oxide, titanium dioxide or rubber gels as well as fibers (such as aramid fibers, glass fibers, carbon fibers, cellulose fibers).

[0055] Other potentially reinforcing fillers include carbon nanotubes (CNTs) including discrete CNTs, so-called hollow carbon fibers (HCFs) and modified CNTs containing one or more functional groups, such as hydroxyl, carboxy and carbonyl groups), graphite and graphene and so-called "carbon-silica dual-phase fillers".

[0056] Zinc oxide is not considered a filler in the context of the present invention.

[0057] A rubber mixture contains at least one silane B with the general empirical formula I) or II) I) (R 1< ) o Si-(R 2< -) m -AC(R 3< 2 )-X II) (R 1< ) o Si-(R 4< -) k -C(R 3< X)-A where o can be 1 or 2 or 3 and the radicals R 1< can be the same or different from one another and are selected from C 1 -C 10 alkoxy groups, C 6 -C 20 phenoxy groups, C 2 -C 10 cyclic dialkoxy groups, C 2 -C 10 dialkoxy groups, C 4 -C 10 cycloalkoxy groups, C 6 -C 20 aryl groups, C 1 -C 10 alkyl groups, C 2 -C 20 alkenyl groups, C 2 -C 20 alkynyl groups, C 7 -C 20 aralkyl groups, halides or alkyl polyether group -O-(R 6< -O) r -R 7< , where the radicals R 6< are the same or different and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic / aromatic bridging C 1 -C 30 hydrocarbon group, r is an integer from 1 to 30 and the radicals R 7< are unsubstituted or substituted, branched or unbranched terminal alkyl, alkenyl, aryl or aralkyl groups, or two R 1< correspond to a dialkoxy group having 2 to 10 carbon atoms, where o is < 3,or two or more silanes according to formula I) and / or II) can be bridged via radicals R 1< or by condensation; and wherein the condition applies that in formula I) and II) in each (R 1< ) o Si group at least one R 1< is selected from those possibilities mentioned above, in which this R 1< i) is bonded to the silicon atom via an oxygen atom or ii) is a halide; and the radicals R 2< and R 4< are branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic / aromatic C 1 -C 30 hydrocarbon groups, where the indices k and m can assume values ​​of 0 or 1; and the radicals R 3< within a molecule can be the same or different and are as defined for R 2< or are hydrogen atoms; and wherein A is an aromatic group; and wherein X is selected from halides, tosylate, mesylate and trifluoromethanesulfonate groups. ,

[0058] The silane with the above-mentioned molecular formula I) or II) has the unit -AC(R 3< 2 )-X or -C(R 3< X)-A, where X is a leaving group which, according to the formula I) or II), is arranged on a carbon atom adjacent to the aromatic compound; in the case of A = phenylene, this is the benzylic position.

[0059] All mentioned radicals R 1< and bridges of one or more silanes via radicals R 1< can be combined with each other within a silyl group.

[0060] In the case that two R 1< correspond to a dialkoxy group with 2 to 10 carbon atoms and then o < 3 (o less than three), the silicon atom is part of a ring system.

[0061] If two silanes according to formula I) and / or II) are bridged together, they share a radical R 1< or are linked to one another via an oxygen atom by combining two Si-R 1< groups. In this way, more than two silanes can be linked to one another. Following the synthesis of the silane according to formula I) and / or II), it is therefore conceivable that two silanes according to formula I) and / or II) are bridged to one another via an oxygen atom or the radicals R 1<. In this way, more than two silanes can also be linked to one another, for example via dialkoxy groups.

[0062] The rubber mixture can thus also contain oligomers which are formed by hydrolysis and condensation or by bridging by means of dialkoxy groups as R 1< of the silanes of the formula I) and / or.

[0063] The silanes according to formulas I) and II) comprise, on the condition that in formula I) and II) in each (R 1< ) o Si group at least one R 1< is selected from those possibilities mentioned above, in which this R 1< i) is bonded to the silicon atom via an oxygen atom or ii) is a halide, in each case at least one radical R 1< which can serve as a leaving group.

[0064] In particular, these are alkoxy groups, phenoxy groups or any other of the above-mentioned groups which are bonded to the silicon atom by an oxygen atom, or halides.

[0065] It is conceivable that the radicals R 1< comprise alkyl groups having 1 to 10 carbon atoms (C 1 -C 10 alkyl group) or alkoxy groups having 1 to 10 carbon atoms (C 1 -C 10 alkoxy group) or halides, particularly preferred are alkoxy groups having 1 to 10 carbon atoms (C 1 -C 10 alkoxy group).

[0066] According to some embodiments, in each silyl group at least one R 1< is a C 1 -C 10 alkoxy group, preferably C 1 -C 6 alkoxy group.

[0067] According to a further embodiment, the radicals R 1< within a silyl group (R 1< ) o Si- are and alkoxy groups having 1 or 2 carbon atoms, i.e. methoxy groups or ethoxy groups, very particularly preferably ethoxy groups, where o is 3. But also in the case of oligomers or in the case that two R 1< form a dialkoxy group, the remaining radicals R 1< are preferably alkyl groups having 1 to 10 carbon atoms or halides or alkoxy groups having 1 to 10 carbon atoms, preferably 1 or 2 carbon atoms, i.e. methoxy groups or ethoxy groups, very particularly preferably ethoxy groups.

[0068] For the purposes of the present invention, ethoxy groups in the formulas of silanes are abbreviated as EtO or OEt. These two notations indicate that alkoxy groups, like ethoxy groups, are bonded to the silicon atom Si via the oxygen atom O.

[0069] In principle, the abbreviations OEt and EtO can be used synonymously within the scope of the present invention.

[0070] According to further embodiments, X in formulas I) and II) is a halide, preferably chloride or bromide or iodide.

[0071] According to one embodiment, X in formula I) and formula II) is chloride.

[0072] This solves the underlying task particularly well.

[0073] The aromatic groups A of formulas I) and II) can, in principle, be any aromatic group. The aromatic groups A may contain heteroatoms and / or bear substituents R 5< (representing a respective hydrogen atom) on one or more atoms of the aromatic framework, in addition to the substituents according to the formula.

[0074] R 5< means additional substituents as part of the aromatic group A, which in the case of two or more substituents may be independently the same or different.

[0075] It is conceivable that the aromatic groups A are selected from the group consisting of phenyl, naphthyl, anthryl, phenanthryl, pyridyl, pyridazyl, pyrimidyl, pyrazyl, triazyl, quinolyl, pyrrolyl, furanyl, thiophenyl, pyrazolyl, imidazolyl, thiazolyl and oxazolyl radicals and derivatives of the groups mentioned, wherein derivatives comprise that the aromatic group carries one or more additional substituents R 5<.

[0076] For simplicity, the groups mentioned are designated as if they were simply bonded to these groups, even if the groups have at least two linkages within the structure, as is always the case in formula I. In the case of phenyl, the IUPAC designation would be "phenylene." However, the term "phenyl" encompasses both terminal phenyl groups and phenylene groups within the context of the present invention. The same applies to all other groups mentioned, unless explicitly stated otherwise.

[0077] The substituent(s) R 5< in formula II) include any conceivable substituents, such as in particular alkyl, alkoxy, hydroxy, carboxy, amine groups or -C(R 3< 2 )-X groups or hydrocarbon radicals which contain 1 to 30 carbon atoms and may contain heteroatoms and / or double bonds and / or further aromatic groups and / or may be branched.

[0078] The linkage of the formula substituents in formula I (i.e., -(R 2< )-Si(R 1< ) o and -C(R 3< )-X) to the respective aromatic group can occur via all conceivable atoms of the aromatic skeleton. For a monocyclic aromatic compound with six skeleton atoms, such as a phenylene residue, this means, for example, that the formula substituents can be arranged in the para, meta, or ortho positions relative to one another.

[0079] The same applies to formula II) in the case that at least one further substituent R 5< is present.

[0080] According to a further embodiment, A in formula I) is a phenyl radical, i.e., a benzene ring. Here, -(R 2< )-Si(R 1< ) o and -C(R 3< )-X are preferably attached in the meta or para position to each other.

[0081] According to a further embodiment, A in formula II) is a phenyl radical, i.e. a benzene ring.

[0082] According to a further embodiment, A in formula II) is a phenyl radical additionally substituted with R 5<, i.e. a substituted benzene ring.

[0083] In this case, (R 1< ) o Si-(R 4< -) k -C(R 3< X)- and R 5< are preferably attached in meta- or para-position to each other.

[0084] Preferably, R 5< is -C(R 3< 2 )-X, where R 3< is both preferably hydrogen atoms and X is preferably a halide, preferably chloride.

[0085] According to one embodiment, in formula I) m is equal to 1, and thus the radical R 2< is present.

[0086] According to one embodiment, in formula I) R 2< is an alkylene group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, very particularly preferably 2 to 8 carbon atoms, for example and in particular 2 carbon atoms and thus an ethylene radical.

[0087] According to a further embodiment, in formula II) k is equal to 1, and thus the radical R 4< is present.

[0088] According to a further embodiment, in formula II) R 4< is an alkylene group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, very particularly preferably 1 to 8 carbon atoms, for example and in particular 1 carbon atom and thus a methylene radical which, together with the radical -C(R 3< X)- according to the formula, forms a substituted ethylene radical.

[0089] According to further embodiments, R 3< in formula II) or at least one R 3< in formula I) is a hydrogen atom.

[0090] Particularly preferably, both R 3< in formula I) are hydrogen atoms and the steric hindrance at the functional group -C(R 3< 2 )X is thus particularly low.

[0091] According to one embodiment, the silane according to formula I) has the following structure according to formula XI): where n is an integer from 0 to 29 and R 5< is defined as described above, and p can take values ​​from 0 to 4, which means that the substituent R 5< with p = 0 is not present or 1 or 2 or 3 or 4 substituents R 5< are present at different positions of the benzene ring in one molecule XI).

[0092] Where: A = phenyl, i.e. a benzene ring, m = 1 and R 2< = alkylene and both R 3< = hydrogen atoms.

[0093] According to a further embodiment, n in formula XI) is 0, whereupon R 2< is an ethylene radical.

[0094] Using a silane according to formula XI), the conflicting objectives of reinforcement and rolling resistance are resolved at a particularly high level, meaning the rubber compound achieves a particularly high level of properties. At the same time, the rubber compound with a silane according to formula XI) exhibits increased stiffness. This, in turn, is an indicator of improved handling.

[0095] Further exemplary silanes B according to formula I) are shown in the following structural formulas:

[0096] According to the invention, the rubber mixture according to the invention contains a mixture of a silane according to the following formula XIa) and a silane according to the following formula XIb) , preferably in a weight ratio of 5:1 to 1:5.

[0097] According to a further embodiment, the silane according to formula II) has the following structure according to formula XII): Here the groups and indices are defined as for formula XI).

[0098] According to a further embodiment, the silane according to formula II) has the following structure according to formula XIII): Here the groups and indices are defined as for formula XI).

[0099] Further exemplary silanes B according to formula II) are shown in the following structural formulas:

[0100] The preparation of the described silanes B is described, for example, in US 7,625,965 B2.

[0101] According to one embodiment, the rubber mixture contains at least one silane B according to formula I).

[0102] According to one embodiment, the rubber mixture contains at least one silane B according to formula II).

[0103] According to one embodiment, the rubber mixture contains at least one silane B according to formula I) and at least one silane B according to formula II).

[0104] The amount of silane B is preferably 0.1 to 30 phf, preferably 1 to 22 phf, particularly preferably 2 to 18.5 phf, most particularly preferably 2 to 10 phf.

[0105] In the event that the rubber mixture contains two or more different silanes according to formula I) and / or II), the quantities stated refer to the total amount of silanes according to formula I) and II) contained.

[0106] It is also conceivable within the scope of the present invention that the above-mentioned silane bin is used in combination with one or more silanes from the prior art.

[0107] The silanes contained according to the invention can be applied to a carrier, for example, wax, polymer, or carbon black, and added in this form to the rubber mixture. The silanes contained according to the invention can be applied to a silica, whereby the bonding can be physical or chemical. Applying the silanes contained according to the invention to silica reduces, for example, the emission of volatile byproducts such as ethanol when using ethoxy-substituted silanes (R 1< = ethoxy).

[0108] Furthermore, the rubber mixture may contain other activators and / or agents for binding fillers, especially carbon black. These may be, for example, the compound S-(3-aminopropyl)thiosulfuric acid, disclosed in EP 2589619 A1, and / or its metal salts, which, particularly when combined with at least one carbon black as a filler, result in very good physical properties of the rubber mixture.

[0109] Furthermore, the rubber mixture may contain conventional additives in the usual parts by weight, which are preferably added in at least one basic mixing stage during its production. These additives include a) ageing inhibitors, such as those of the PPD family (phenylenediamines) and here for example 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), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), b) activators, such as for example zinc oxide and fatty acids (e.g. stearic acid) and / or other activators, such as zinc complexes such as for example zinc ethylhexanoate, c) waxes, d) hydrocarbon resins, such as in particular tackifying resins, e) mastication aids, such as for example B. 2,2'-dibenzamidodiphenyl disulfide (DBD) and f) processing aids, such as in particular fatty acid esters and metal soaps, such as zinc soaps and / or calcium soaps g) plasticizers.

[0110] The plasticizers used in the context of the present invention include all plasticizers known to the person skilled in the art, such as aromatic, naphthenic or paraffinic mineral oil plasticizers, such as MES (mild extraction solvate) or RAE (residual aromatic extract) or TDAE (treated distillate aromatic extract), or rubber-to-liquid oils (RTL) or biomass-to-liquid oils (BTL), preferably with a polycyclic aromatics content of less than 3% by weight according to method IP 346, or triglycerides, such as rapeseed oil, or factices or hydrocarbon resins or liquid polymers whose average molecular weight (determined by GPC = gel permeation chromatography, based on BS ISO 11344:2004) is between 500 and 20,000 g / mol. If additional liquid polymers are used as plasticizers in the rubber mixture according to the invention, these are not included as rubber in the calculation of the composition of the polymer matrix.

[0111] The plasticizer is preferably selected from the group consisting of the above-mentioned plasticizers.

[0112] The plasticizer is particularly preferably selected from the group consisting of hydrocarbon resins, liquid polymers and mineral oils.

[0113] When using mineral oil, this is preferably selected from the group consisting of DAE (Distilled Aromatic Extracts) and / or RAE (Residual Aromatic Extract) and / or TDAE (Treated Distilled Aromatic Extracts) and / or MES (Mild Extracted Solvents) and / or naphthenic oils.

[0114] According to a preferred embodiment of the invention, the rubber mixture contains at least one mineral oil plasticizer, preferably at least TDAE and / or RAE as plasticizer. This results in particularly good processability, in particular good miscibility of the rubber mixture.

[0115] According to a preferred embodiment of the invention, the rubber mixture contains at least one liquid polymer as a plasticizer.

[0116] According to a preferred embodiment of the invention, the rubber mixture contains at least one hydrocarbon resin as a plasticizer.

[0117] It is clear to those skilled in the art that hydrocarbon resins are polymers composed of monomers, whereby the hydrocarbon resin is formally composed of derivatives of the monomers through the linkage of the monomers to one another. However, these hydrocarbon resins are not considered rubbers within the scope of the present invention. The term "hydrocarbon resins" within the scope of the present application encompasses resins that contain carbon atoms and hydrogen atoms and may optionally contain heteroatoms, such as, in particular, oxygen atoms. The hydrocarbon resin can be a homopolymer or a copolymer. In the present application, a homopolymer is understood to mean a polymer that, according to Römpp Online Version 3.28, "is formed from monomers of only one type."The monomers may be any monomers of hydrocarbon resins known to the person skilled in the art, such as aliphatic C 5 monomers, other unsaturated compounds which can be cationically polymerized, containing aromatics and / or terpenes and / or alkenes and / or cycloalkenes.

[0118] In a preferred embodiment of the invention, the hydrocarbon resin is selected from the group consisting of aliphatic C 5 resins and hydrocarbon resins of alpha-methylstyrene and styrene.

[0119] The hydrocarbon resin preferably has a softening point according to ASTM E 28 (Ring and Ball) of 10 to 180 °C, particularly preferably of 60 to 150 °C, most preferably of 80 to 99 °C. Furthermore, the hydrocarbon resin preferably has a molecular weight Mw of 500 to 4000 g / mol, preferably of 1300 to 2500 g / mol.

[0120] The proportion of the total amount of further additives is preferably 3 to 150 phr, preferably 3 to 100 phr and particularly preferably 5 to 80 phr.

[0121] The total amount of other additives may include zinc oxide (ZnO). This can be any type of zinc oxide known to those skilled in the art, such as ZnO granules or powder. The conventionally used zinc oxide generally has a BET surface area of ​​less than 10 m² / g. However, a zinc oxide with a BET surface area of ​​10 to 100 m² / g, such as so-called "nano-zinc oxides," can also be used.

[0122] In particular, when using the rubber mixture according to the invention for the inner components of a tire or a technical rubber article which have direct contact with existing reinforcements, a suitable adhesive system, often in the form of adhesive resins, is generally added to the rubber mixture.

[0123] Vulcanization is preferably carried out in the presence of sulfur and / or sulfur donors and with the aid of vulcanization accelerators, whereby some vulcanization accelerators can also act as sulfur donors. Sulfur and / or other sulfur donors as well as one or more accelerators are added to the rubber mixture in the final mixing step. The accelerator is selected from the group consisting of thiazole accelerators and / or mercapto accelerators and / or sulfenamide accelerators and / or thiocarbamate accelerators and / or thiuram accelerators and / or thiophosphate accelerators and / or thiourea accelerators and / or xanthate accelerators and / or guanidine accelerators and / or polyetheramine accelerators.

[0124] Preference is given to using at least one sulfenamide accelerator selected from the group consisting of N-cyclohexyl-2-benzothiazolesufenamide (CBS) and / or N,N-dicyclohexylbenzothiazole-2-sulfenamide (DCBS) and / or benzothiazyl-2-sulfenemorpholide (MBS) and / or N-tert-butyl-2-benzothiazylsulfenamide (TBBS).

[0125] All sulfur-donating substances known to the person skilled in the art can be used as the sulfur-donating substance. If the rubber mixture contains a sulfur-donating substance, it is preferably selected from the group comprising, for example, thiuram disulfides, such as tetrabenzylthiuram disulfide (TBzTD) and / or tetramethylthiuram disulfide (TMTD) and / or tetraethylthiuram disulfide (TETD), and / or thiuram tetrasulfides, such as dipentamethylenethiuram tetrasulfide (DPTT), and / or dithiophosphates, such as

[0126] DipDis (bis-(diisopropyl)thiophosphoryl disulfide) and / or bis(O,O-2-ethylhexyl-thiophosphoryl)polysulfide (e.g. Rhenocure SDT 50 ®< , Rheinchemie GmbH) and / or zinc dichloryldithiophosphate (e.g. Rhenocure ZDT / S ®< , Rheinchemie GmbH) and / or zinc alkyldithiophosphate, and / or 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane and / or diarylpolysulfides and / or dialkylpolysulfides.

[0127] Other network-forming systems, such as those available under the trade names Vulkuren®, Duralink®, or Perkalink®, or network-forming systems as described in WO 2010 / 049216 A2, can also be used in the rubber compound. This system contains a vulcanizing agent that crosslinks with a functionality greater than four and at least one vulcanization accelerator.

[0128] The required amount of additional sulfur in the form of elemental sulfur and / or additional sulfur donor depends on the application of the respective rubber compound. The respective dosage amounts are known to those skilled in the art. When adding elemental sulfur in a rubber compound for the bead of vehicle tires, for example, the amounts range from 0 to 5 phr. For vehicle tire treads, which generally have a lower sulfur content than the bead, the amount of elemental sulfur to be added is preferably from 0 to 4 phr.

[0129] According to an advantageous development of the invention, several accelerators are used.

[0130] According to an advantageous embodiment of the invention, a sulfenamide accelerator, particularly preferably TBBS, is used in combination with the guanidine accelerator DPG (diphenylguanidine). The amount of DPG is 0 to 5 phr, preferably 0.1 to 3 phr, particularly preferably 0.5 to 2.5 phr, most preferably 1 to 2.5 phr.

[0131] According to a further advantageous embodiment of the invention, a sulfenamide accelerator, particularly preferably CBS, is used in combination with polyetheramine accelerators (for example, Jeffamine®< D230). The amount of polyetheramine accelerators (for example, Jeffamine®< D230) is 0.1 to 5 phr, preferably 0.1 to 3 phr, particularly preferably 0.5 to 2.5 phr, most preferably 1 to 2.5 phr.

[0132] In addition, vulcanization retarders may be present in the rubber mixture. The terms "vulcanized" and "crosslinked" are used synonymously in the context of the present invention.

[0133] The above-described inventive rubber mixture is particularly suitable for use in vehicle tires, especially pneumatic vehicle tires. In principle, application in all tire components is conceivable, particularly in a tread, especially in the cap of a tread with a cap / base construction, as already described above.

[0134] For use in vehicle tires, the mixture is preferably formed into a tread shape as a ready-mix before vulcanization and applied as usual during the production of the green vehicle tire.

[0135] The rubber mixture according to the invention for use as a sidewall or other body mixture in vehicle tires is produced as already described. The difference lies in the shaping after the extrusion process or calendering of the mixture. The resulting shapes of the still unvulcanized rubber mixture for one or more different body mixtures are then used to construct a green tire.

[0136] The body mixture refers to the rubber mixtures for the other components of a tire, such as the separator plate, inner liner (inner layer), apex, belt, shoulder, belt tread, carcass, bead reinforcement, bead tread, horn tread and bandage. To use the rubber mixture according to the invention in belts and straps, in particular in conveyor belts, the extruded, still unvulcanized mixture is formed into the appropriate shape and, during or after the process, often provided with reinforcements, e.g., synthetic fibers or steel cords. This usually results in a multi-layer structure consisting of one or more layers of rubber mixture, one or more layers of the same or different reinforcements and one or more further layers of the same or a different rubber mixture.

[0137] The invention will now be explained in more detail using comparative and exemplary embodiments, which are summarized in the following tables.

[0138] The comparison mixtures are marked with V, the mixtures according to the invention are marked with E. The quantity of silanes in phf refers to the respective amount of silica.

[0139] The mixtures were prepared under standard conditions in several stages in a laboratory tangential mixer. Test specimens were produced from all mixtures by vulcanization, and these specimens were used to determine material properties typical for the rubber industry. The following test procedures were used for the specimen tests described above: Rebound resilience at 70°C according to ISO 4662 Conditioned Shore A hardness at room temperature in accordance with DIN ISO 7619-1, preconditioned ten times with 5 MPa and then tested according to ISO 868 Stress value at 200 % and 300 % elongation (M200 or M300) at room temperature according to ISO 37 Abrasion at room temperature according to DIN / ISO 4649 Loss factor tan d, synonymous with tan 8, at 55°C from dynamic-mechanical measurement according to DIN 53 513

[0140] Compared to the comparison mixtures, the rubber mixture according to the invention exhibits an improved property profile, particularly with regard to abrasion and rolling resistance behavior, as well as the reinforcing effect. The rubber mixture according to the invention exhibits an improved reinforcing effect, which is evident from the higher values ​​for M200 and M300 and thus a higher stiffness at high elongations (200% and 300%, respectively). Thus, the rubber mixture according to the invention also exhibits improved handling behavior. Table 1 Components Unit V1 V2 V3 E2 NR a)< phr 100 100 100 100 Silica b)< phr 46 46 37 37 Silane c)< phf 7,2 - 7,2 - Silane d)< phf - 7,7 - 7,7 Soot N339 phr 3 3 - - Soot N121 phr - - 12 12 Plasticizer TDAE phr 3 3 3 3 ZnO phr 3 3 3 3 Additives e)< phr 8 8 8 8 Accelerator f)< phr 3 3 3 3 sulfur phr 1,6 1,6 1,6 1,6 Characteristics Cond. Shore hardness (RT) Shore A 57,5 58,9 58,9 65,5 Rebound load (70 °C) % 70,9 72,5 68,9 71,3 Module 200 (RT) MPa 5,5 7,8 5,8 10,3 Module 300 (RT) MPa 10,3 15,6 11,0 18,8 Tan d MPa 0,077 0,071 0,088 0,078 Abrasion mm 3< 123 107 115 108 Substances used a< NR, TSR b< Zeosil 1165MP, Rhodia, CTAB 155m 2< / g, BET 160 m 2< / g c< TESPD, Evonik d< Mixture of silane according to formula XIa) and XIb) in a ratio of 2 to 3 e< Anti-aging agent, ozone protection wax, stearic acid f< TBBS, DPG

Claims

1. Sulfur-crosslinkable rubber mixture containing at least the following constituents: - at least one diene rubber and - 5 to 500 phr of at least one silica and - 5 to 150 phr of at least one carbon black and - a mixture of silanes B of formula XIa) and of formula XIb) 2. Rubber mixture according to Claim 1, characterized in that the weight ratio of the amount of silica to the amount of carbon black is 17:1 to 1:20.

3. Rubber mixture according to any of the preceding claims, characterized in that it contains 5 to 20 phr of at least one carbon black and 10 to 100 phr, preferably 20 to 100 phr, of at least one silica.

4. Rubber mixture according to any of the preceding claims, characterized in that it contains 0.1 to 30 phf of silane B.

5. Rubber mixture according to any of the preceding claims, characterized in that it contains the silanes according to formula XIa) and formula XIb) in the weight ratio 5:1 to 1:5.

6. Rubber mixture according to any of the preceding claims, characterized in that the diene rubber is 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).

7. Vulcanizate obtained by the sulfur vulcanization of at least one rubber mixture according to any of Claims 1 to 6.

8. Vehicle tyre, characterized in that it comprises at least one vulcanizate according to Claim 7 in at least one component.

9. Vehicle tyre according to Claim 8, characterized in that it includes at least one vulcanizate according to Claim 7 in the tread.

10. Use of a rubber mixture according to any of Claims 1 to 6 for producing a rubber article, especially an air spring, a bellows, a conveyor belt, a strap, a drive belt, a hose, a rubber band, a profile, a seal, a membrane, tactile sensors for medical applications or robotics applications, or a shoe sole or parts thereof.