Sulfur-crosslinkable rubber compound, vulcanized rubber compound, and vehicle tires

Description

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

[0002] The rubber composition of the tread largely determines the driving characteristics of a vehicle tire, especially a pneumatic vehicle tire.

[0003] 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, these rubber compounds for pneumatic vehicle tires, belts, and hoses are subject to very high demands.

[0004] There are conflicting objectives between most of the known tire properties such as wet grip, dry braking, handling, rolling resistance, winter properties, abrasion behavior and tear properties.

[0005] Particularly in the case of pneumatic vehicle tires, numerous attempts have been made to positively influence the properties of the tire by varying the polymer components, fillers and other additives, especially in the tread compound.

[0006] It must be taken into account that an improvement in one tire property often results in a deterioration in another property.

[0007] For example, in a given compound system, there are various known ways to optimize handling performance by increasing the stiffness of the rubber compound. Examples include increasing the filler content and increasing the network node density of the vulcanized rubber compound. While an increased filler content results in disadvantages in rolling resistance, raising the network leads to a deterioration in the tear properties and the wet grip indicators of the rubber compound.

[0008] It is also known that rubber compounds, especially for the tread of pneumatic vehicle tires, can contain silica as a filler. Furthermore, it is known that advantages regarding rolling resistance behavior and processability of the rubber compound arise when the silica is bonded to the polymer(s) using silane coupling agents.

[0009] Silane coupling agents known in the prior art are disclosed, for example, in DE 2536674 C3 and DE 2255577 C3.

[0010] In principle, a distinction can be made between silanes which only bind to silica or comparable fillers and for this purpose in particular have at least one silyl group, and silanes which, in addition to a silyl group, have a reactive sulfur group, such as in particular an S x group (with x > or equal to 2) or a mercapto group SH or blocked S-SG group, where SG stands for protecting group, so that the silane can also bind to polymers by reaction of the S x or SH group or the S-SG group after removal of the protecting group during sulfur vulcanization.

[0011] In addition, some combinations of selected silanes are disclosed in the prior art.

[0012] EP 1085045 B1 discloses a rubber mixture containing a combination of a polysulfidic silane (a mixture with 69 to 79 wt.% disulfide content, 21 to 31 wt.% trisulfide content, and 0 to 8 wt.% tetrasulfide content) and a silane that contains only one sulfur atom and therefore cannot bond to polymers. Such a silane mixture, in combination with carbon black and silica as fillers, achieves an optimized property profile with regard to laboratory predictors for, among other things, rolling resistance and abrasion, and optimal tire properties when used in the tread of vehicle tires.

[0013] WO 2012092062 discloses a combination of a blocked mercaptosilane (NXT) with filler-reinforcing silanes which have non-reactive alkyl groups between the silyl groups.

[0014] WO 2019105602 A1 also discloses a rubber mixture containing a combination of a polymer-binding silane and a filler-reinforcing silane in a polymer blend of 72 phr SSBR, 18 phr BR and 10 phr NR.

[0015] The present invention is based on the object of providing a rubber compound that, compared to the prior art, exhibits a further improvement in its property profile, including abrasion behavior, rolling resistance, and handling behavior, particularly in terms of stiffness. At the same time, the other physical properties of the rubber compound for tire application should not be negatively affected or should even be improved.

[0016] This task is solved by a rubber mixture that contains the following components: 80 to 100 phr of at least one polyisoprene selected from natural and synthetic polyisoprene; 10 to 500 phr of at least one silicic acid; and 1 to 30 phr of at least one silane A having the general empirical formula AI) and / or A-XI) AI) (R 1< ) o Si-R 2< -(SR 3< ) q -S x -(R 3< -S) q -R 2< -Si(R 1< ) o ; A-XI) (R 1< ) o Si-R 2< -(SR 3< ) s -SX; and 0.5 to 30 phr of at least one silane B having the general empirical formula BI) BI) (R 1< ) o Si-R 4< -Si(R 1< ) o 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 divalent 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 monovalent 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 the formulas AI) and / or A-XI) and / or BI) can be bridged via radicals R 1< or by condensation; and wherein the condition applies that in the formulas AI) and A-XI) and BI) 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 wherein the radicals R 2< , R 3< and R 4< can be the same or different in each molecule and within a molecule and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic / aromatic divalent C 1 -C 30 hydrocarbon groups, which may also contain heteroatoms, such as oxygen (O) and / or nitrogen (N), as well as functional groups, such as urea groups and / or amide groups,may contain; and wherein x is an integer from 2 to 10 and q is 0 or 1 or 2 or 3; and wherein s is 0 or 1 or 2 or 3; and X is a hydrogen atom or a -C(=O)-R 8< group, wherein R 8< is selected from hydrogen, C 1 -C 20 alkyl groups, C 6 -C 20 aryl groups, C 2 -C 20 alkenyl groups and C 7 -C 20 aralkyl groups. ,

[0017] Surprisingly, it has been found that the combination of silanes A and B, whereby silane A can also bind to polymers due to the polysulfidic S x group or the reactive SX group, achieves an improvement in the property profile comprising the abrasion behavior, the rolling resistance behavior and the handling behavior, in particular through the stiffness.

[0018] A further subject of the present invention is a vulcanizate of at least one rubber mixture according to the invention.

[0019] 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 at least one vulcanizate of the invention at least in the tread.

[0020] The vulcanizate according to the invention and the vehicle tire according to the invention are characterized by an optimized property profile from the above-mentioned properties.

[0021] 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.

[0022] 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.

[0023] The rubber mixture according to the invention is also suitable for other components of vehicle tires, such as, in particular, the flange profile, as well as for inner tire components. 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.

[0024] 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.

[0025] 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 Mw 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 coupling agents for fillers.

[0026] In the context of the present application, phf refers to the silica present, which means that other fillers that may be present, such as carbon black, are not included in the calculation of the amount of silane.

[0027] The rubber mixture according to the invention contains 80 to 100 phr, preferably 90 to 100 phr, particularly preferably 95 to 100 phr, of at least one polyisoprene selected from natural (NR) and synthetic polyisoprene (IR). The polyisoprene(s) preferably have a weight-average molecular weight Mw according to GPC of 250,000 to 5,000,000 g / mol.

[0028] According to preferred embodiments of the invention, the rubber mixture according to the invention contains 100 phr of at least one polyisoprene selected from natural (NR) and synthetic polyisoprene (IR).

[0029] The natural and / or synthetic polyisoprene in all embodiments can be either cis-1,4-polyisoprene or 3,4-polyisoprene. However, the use of cis-1,4-polyisoprenes with a cis-1,4 content of > 90 wt.% is preferred. Such a polyisoprene can be obtained by stereospecific polymerization in solution with Ziegler-Natta catalysts or using finely divided lithium alkyls. Natural rubber (NR) is also a cis-1,4-polyisoprene in which the cis-1,4 content in the natural rubber is greater than 99 wt.%.

[0030] Furthermore, a mixture of one or more natural polyisoprenes with one or more synthetic polyisoprene(s) is also conceivable.

[0031] 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).

[0032] In case the rubber compound contains less than 100 phr NR and / or IR, it contains at least one other diene rubber.

[0033] 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.

[0034] The further diene rubber is preferably selected from the group consisting of epoxidized polyisoprene, butadiene rubber (BR), butadiene-isoprene rubber, solution-polymerized styrene-butadiene rubber (SSBR), emulsion-polymerized styrene-butadiene rubber (ESBR), styrene-isoprene rubber, liquid rubbers with a molecular weight M w of greater than 20,000 g / mol, halobutyl rubber, polynorbornene, isoprene-isobutylene copolymer, ethylene-propylene-diene rubber, nitrile rubber, chloroprene rubber, acrylate rubber, fluorine rubber, silicone rubber, polysulfide rubber, epichlorohydrin rubber, Styrene-isoprene-butadiene terpolymer, hydrogenated acrylonitrile-butadiene rubber and hydrogenated styrene-butadiene rubber.

[0035] 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 preferred blend compositions for these rubbers, which are known to those skilled in the art—specific with regard to fillers, plasticizers, vulcanization systems, and additives—are used.

[0036] 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.

[0037] According to advantageous embodiments, the further diene rubber, in particular when the rubber mixture is used in vehicle tires, is selected from the group consisting of butadiene rubber (BR), solution-polymerized styrene-butadiene rubber (SSBR), emulsion-polymerized styrene-butadiene rubber (ESBR), butyl rubber (IIR) and halobutyl rubber.

[0038] According to an advantageous embodiment of the invention, the rubber mixture contains 80 to 99 phr NR and 1 to 20 phr BR, preferably 80 to 90 phr NR and 10 to 20 phr BR, for example and in particular 80 phr NR and 20 phr BR.

[0039] Such a rubber mixture is particularly suitable for treads, in particular for commercial vehicle tires, and also solves the problem underlying the invention particularly well while providing particularly good other tire properties.

[0040] According to the invention, the rubber mixture contains 10 to 500 phr of at least one silica.

[0041] 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 if a finely divided, precipitated silica is used which has a nitrogen surface area (BET surface area) (according to DIN ISO 9277 and DIN 66132) of 35 to 400 m 2 < / g, preferably of 35 to 350 m 2 < / g, particularly preferably of 85 to 320 m 2 < / g and very particularly preferably of 120 to 235 m 2 < / g, and a CTAB surface area (according to ASTM D 3765) of 30 to 400 m 2 < / g, preferably of 30 to 330 m 2 < / g, particularly preferably of 80 to 300 m 2 < / g and very particularly preferably of 110 to 230 m 2 < / g.

[0042] Such silicas, for example, lead to particularly good physical properties of the vulcanizates in rubber compounds for tire treads. Furthermore, they can offer advantages in compound processing by reducing mixing times while maintaining consistent product properties, leading to improved productivity. Thus, both Ultrasil®< VN3 (trade name) from Evonik and highly dispersible silicas, so-called HD silicas (e.g., Zeosil®< 1165 MP from Solvay), can be used as silicas.

[0043] According to a preferred embodiment of the invention, the rubber mixture according to the invention contains 20 to 300 phr, preferably 20 to 250 phr, particularly preferably 20 to 150 phr and very particularly preferably 20 to 60 phr of at least one silica.

[0044] 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.

[0045] The terms "silicic acid" and "silica" are used synonymously in the present invention.

[0046] The rubber mixture according to the invention may further contain at least one carbon black, in particular an industrial carbon black.

[0047] All types of soot known to the expert person can be considered as soot.

[0048] In one embodiment, the carbon black has an iodine number, according to ASTM D 1510, which is also referred to as 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.

[0049] The DBP number according to ASTM D 2414 determines the specific absorption volume of a carbon black or a light filler using dibutyl phthalate.

[0050] The use of such a carbon black type 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 if only one type of carbon black is used in the respective rubber compound, but various types of carbon black can also be mixed into the rubber compound. The total amount of carbon black contained is preferably 0 to 250 phr.

[0051] According to an advantageous embodiment of the invention, the rubber mixture contains 0 to 20 phr, preferably 0 to 10 phr of at least one carbon black and 10 to 500 phr, preferably 10 to 60 phr of at least one silica.

[0052] According to a further advantageous embodiment of the invention, the rubber mixture contains 30 to 150 phr of at least one carbon black and 10 to 30 phr of at least one silica and thus represents a partial silica mixture.

[0053] The rubber mixture according to the invention may contain further fillers, preferably in the smallest possible amounts, i.e., preferably 0 to 20 phr, particularly preferably 0 to 10 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).

[0054] 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".

[0055] Zinc oxide is not considered a filler in the context of the present invention.

[0056] According to the invention, the rubber mixture contains 1 to 30 phf, preferably 2 to 20 phf, of at least one silane A with the general empirical formula AI) and / or A-XI) AI) (R 1< ) o Si-R 2< -(SR 3< ) q -S x -(R 3< -S) q -R 2< -Si(R 1< ) o ; A-XI) (R 1< ) o Si-R 2< -(SR 3< ) s -SX, and 0.5 to 30 phf, preferably 0.5 to 20 phf, particularly preferably 1 to 10 phf, of at least one silane B with the general empirical formula BI) BI) (R 1< ) o Si-R 4< -Si(R 1< ) o , with the above definitions.

[0057] The at least one silane A contained according to the invention is, through the SX group (silane A-XI)), a silane which can bind to polymers by splitting off X, i.e. the hydrogen atom or the -C(=O)-R 8< group, or, through the S x group (silane AI) and because x is at least 2, a silane which can bind to polymers by means of the sulfur group S x.

[0058] In each individual molecule, x is an integer from 2 to 8, although a mixture of different molecules with different values ​​for x may also be present. Preferably, x is an integer from 2 to 4. According to a particularly advantageous embodiment of the invention, x is equal to 2.

[0059] Different silanes with different X groups may also be present in the mixture. X is a hydrogen atom or a -C(=O)-R 8< group, where R 8< is selected from hydrogen, C 1 -C 20 alkyl groups, preferably C 1 -C 10 alkyl groups, C 6 -C 20 aryl groups, preferably phenyl, C 2 -C 20 alkenyl groups, and C 7 -C 20 aralkyl groups.

[0060] Preferably, X is a -C(=O)-R 8< group, where R 8< is particularly preferably a C 1 -C 20 alkyl group, again preferably a C 1 -C 10 alkyl group; X is thus an alkanoyl group.

[0061] According to a further advantageous embodiment, the alkanoyl group has a total of 7 to 9 carbon atoms, in particular 8 carbon atoms.

[0062] The index q can take the values ​​0 or 1 or 2 or 3. Preferably, q is equal to 0 or 1.

[0063] The index s can take the values ​​0 or 1 or 2 or 3. Preferably, s is equal to 0.

[0064] The silane B contained in the invention does not contain any sulfur atoms, so it cannot bind to polymers.

[0065] The following statements regarding R 1< , R 2< , R 3< and R 4< apply to the silanes according to the formulas AI), A-XI) and BI), if present in the molecules and unless otherwise stated.

[0066] R 2< , R 3< and R 4< can in particular and preferably be -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 -, -CH(CH 3 )-, -CH 2 CH(CH 3 )-, -CH(CH 3 )CH 2 -, -C(CH 3 ) 2 -, -CH(C 2 H 5 )-, -CH 2 CH 2 CH(CH 3 )-, -CH(CH 3 )CH 2 CH 2 -, -CH 2 CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 - or or be.

[0067] Preferably, R 2< is an alkylene group having 2 or 3 carbon atoms and particularly preferably -CH 2 CH 2 - or -CH 2 CH 2 CH 2 -, particularly preferably -CH 2 CH 2 CH 2 -.

[0068] Preferably, R 3< is an alkylene group having 4 to 8 carbon atoms and particularly preferably -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, particularly preferably -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -.

[0069] Preferably, R 4< is an alkylene group having 5 to 10 carbon atoms and preferably -CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -, particularly preferably -CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -.

[0070] However, R 2< , R 3< and R 4< can also contain heteroatoms, such as oxygen (O) and / or nitrogen (N), as well as functional groups, such as urea groups and / or amide groups.

[0071] 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.

[0072] 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.

[0073] In the event that two silanes according to formula AI) and / or A-XI) and / or BI) are bridged with one another, 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 AI) and / or A-XI) and / or BI), it is therefore conceivable that two silanes according to formula AI) and / or A-XI) and / or BI) are bridged with 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.

[0074] The rubber mixture according to the invention 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 A and / or silanes B (silanes of the formula AI) and / or A-XI) and / or BI)).

[0075] The silanes according to the formulas AI) and A-XI) and BI) comprise, on the condition that in the formulas AI) and A-XI) and BI) 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.

[0076] In particular, these are alkoxy groups, phenoxy groups or any other of the above-mentioned groups that are bonded to the silicon atom with an oxygen atom, or halides.

[0077] It is preferred that the radicals R 1< comprise alkyl groups having 1 to 6 carbon atoms or alkoxy groups having 1 to 6 carbon atoms or halides, particularly preferred are alkoxy groups having 1 to 6 carbon atoms.

[0078] According to a particularly advantageous embodiment of the invention, the radicals R 1< within a silyl group (R 1< ) o Si- are equal to and alkoxy groups having 1 or 2 carbon atoms, i.e. methoxy groups or ethoxy groups, very particularly preferably ethoxy groups, where o is equal to 3.

[0079] But also in the case of oligomers or in the case where two R 1< form a dialkoxy group, the remaining radicals R 1< are preferably alkyl groups having 1 to 6 carbon atoms or halides or alkoxy groups having 1 to 6 carbon atoms, preferably 1 or 2 carbon atoms, i.e. methoxy groups or ethoxy groups, very particularly preferably ethoxy groups.

[0080] 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.

[0081] In principle, the abbreviations OEt and EtO can be used synonymously within the scope of the present invention.

[0082] Silanes A of formula AI) may be preferred: (EtO) 3 Si-CH 2 -S 2 -CH 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -S 2 -(CH 2 ) 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 3 -S 2 -(CH 2 ) 3 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 6 -S 2 -(CH 2 ) 6 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 8 -S 2 -(CH 2 ) 8 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 12 -S 2 -(CH 2 ) 12 -Si(OEt) 3 , (EtO) 3 Si-CH 2 -S 4 -CH 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -S 4 -(CH 2 ) 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 3 -S 4 -(CH 2 ) 3 -Si(OEt) 3 , (EtO) 3 Si-CH 2 -S-(CH 2 )-S 2 -(CH 2 )-S-CH 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -S-(CH 2 )-S 2 -(CH 2 )-S-(CH 2 ) 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-S 2 -(CH 2 )-S-(CH 2 ) 3 -Si(OEt) 3 , (EtO) 3 Si-CH 2 -S-(CH 2 ) 2 -S 2 -(CH 2 ) 2 -S-CH 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -S-(CH 2 ) 2 -S 2 -(CH 2 ) 2 -S-(CH 2 ) 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -S 2 -(CH 2 ) 2 -S-(CH 2 ) 3 -Si(OEt) 3 , (EtO) 3 Si-CH 2 -S-(CH 2 ) 3 -S 2 -(CH 2 ) 3 -S-CH 2 -Si(OEt) 3 , (EtO) 3 Si-CH 2 -S-(CH 2 ) 3 -S 2 -(CH 2 ) 3 -S-CH 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -S-(CH 2 ) 3 -S 2 -(CH 2 ) 3 -S-(CH 2 ) 2 -Si(OEt) 3 ,(EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -S 2 -(CH 2 ) 3 -S-(CH 2 ) 3 -Si(OEt) 3 , (EtO) 3 Si-CH 2 -S-(CH 2 ) 4 -S 2 -(CH 2 ) 4 -S-CH 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -S-(CH 2 ) 4 -S 2 -(CH 2 ) 4 -S-(CH 2 ) 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 4 -S 2 -(CH 2 ) 4 -S-(CH 2 ) 3 -Si(OEt) 3 , (EtO) 3 Si-CH 2 -S-(CH 2 ) 5 -S 2 -(CH 2 ) 5 -S-CH 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -S-(CH 2 ) 5 -S 2 -(CH 2 ) 5 -S-(CH 2 ) 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 5 -S 2 -(CH 2 ) 5 -S-(CH 2 ) 3 -Si(OEt) 3 , (EtO) 3 Si-CH 2 -S-(CH 2 ) 6 -S 2 -(CH 2 ) 6 -S-CH 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -S-(CH 2 ) 6 -S 2 -(CH 2 ) 6 -S-(CH 2 ) 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -S 2 -(CH 2 ) 6 -S-(CH 2 ) 3 -Si(OEt) 3 . ,

[0083] According to a preferred embodiment of the invention, the silane A according to the variant according to formula AI) has the following structure according to formula A-II): where x is an integer from 2 to 10.

[0084] With a silane A according to formula A-II), particularly good handling predictors as well as very good rolling resistance and abrasion behavior are achieved, while at the same time good processability is achieved.

[0085] According to a particularly advantageous embodiment of the invention, it is preferred if x is equal to 2, which results in particular in optimized handling indicators, advantageous rolling resistance predictors and very good abrasion behavior.

[0086] In this embodiment, the silane has the formula (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -S 2 -(CH 2 ) 6 -S-(CH 2 ) 3 -Si(OEt) 3 .

[0087] There may also be a mixture of at least two silanes according to formula A-II) which have a different number of sulfur atoms (x = 2 or 3 or 4 or 5 or 6 or 7 or 8), wherein any possible combination is conceivable, and in each of the mixtures the monosulfide with x equal to 1 may additionally be present.

[0088] According to a preferred advantageous embodiment of the invention, the silane A according to the variant according to formula AI) has the following structure according to formula A-III): A-III) (EtO) 3 Si-(CH 2 ) 3 -S x -(CH 2 ) 3 -Si(OEt) 3 , where x is an integer from 2 to 8.

[0089] According to a particularly advantageous embodiment of the invention, it is preferred if x is equal to 2, which results in particular in optimized handling indicators, advantageous rolling resistance predictors, and very good abrasion behavior. The silane according to formula A-III) with x equal to 2 is also known to those skilled in the art as TESPD (3,3'-bis(triethoxysilylpropyl) disulfide), and it is known to those skilled in the art that it can be present in a mixture with the higher sulfides (e.g., x equal to 3 or 4) and / or the monosulfide (with x equal to 1).

[0090] Silanes A of formula A-XI) may be preferred: (EtO) 3 Si-(CH 2 ) 3 -SC(=O)-C 7 H 15 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-CH 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 2 H 5 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 3 H 7 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 4 H 9 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 5 H 11 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 6 H 13 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 7 H 15 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 9 H 19 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 11 H 23 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 13 H 27 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 15 H 31 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 )-SC(=O)-C 17 H 35 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-CH 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 2 H 5 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 3 H 7 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 4 H 9 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 5 H 11 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 6 H 13 ,(EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 7 H 15 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 9 H 19 , (Et0) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 11 H 23 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 13 H 27 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 15 H 31 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 2 -SC(=O)-C 17 H 35 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-CH 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 2 H 5 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 3 H 7 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 4 H 9 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 5 H 11 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)C 6 H 13 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 7 H 15 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)C 9 H 19 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 11 H 23 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 13 H 27 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 15 H 31 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 3 -SC(=O)-C 17 H 35 ,(EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-CH 3 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 2 H 5 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 3 H 7 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 4 H 9 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 5 H 11 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 6 H 13 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 7 H 15 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 9 H 19 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 11 H 23 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 13 H 27 , (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 15 H 31, (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-C 17 H 35 . ,

[0091] According to advantageous embodiments of the invention, at least one silane having the general empirical formula A-XI) is contained, where s is preferably equal to 0.

[0092] According to a preferred embodiment of the invention, the silane A according to the variant according to formula A-XI) has the following structure according to formula A-XII): A-XII) (EtO) 3 Si-(CH 2 ) 3 -SC(=O)-(CH 2 ) 6 -CH 3

[0093] In this particularly advantageous embodiment, the rubber mixture according to the invention shows a particularly optimized property profile of the handling indicators (in particular stiffness), rolling resistance behavior and abrasion behavior.

[0094] According to a further preferred embodiment of the invention, the silane A according to the variant according to formula A-XI) has the following structure according to formula A-XIII): A-XIII) (EtO) 3 Si-(CH 2 ) 3 -S-(CH 2 ) 6 -SC(=O)-CH 3 .

[0095] In this particularly advantageous embodiment, the rubber mixture according to the invention shows a particularly optimized property profile of the handling indicators (in particular stiffness), rolling resistance behavior and abrasion behavior.

[0096] It is also conceivable that the rubber mixture according to the invention contains a mixture of two or more of the silanes according to the formulas AI) and / or A-XI), in particular A-XII) or A-XIII).

[0097] The total amount of silanes A contained, which fall under the formula AI) and A-XI), is in any case 1 to 30 phf, preferably 2 to 20 phf.

[0098] According to an advantageous development of the invention, the amount of silanes A contained is at least 2.5 phf.

[0099] According to a further advantageous development of the invention, the amount of silanes A contained is at least 5 phf.

[0100] According to a further advantageous development of the invention, the amount of silanes A contained is at least 10 phf.

[0101] The preferred minimum quantities also apply if only one type A silane is included.

[0102] In particular, with the preferred and particularly preferred quantities and the mentioned further developments or embodiments, very good properties with regard to rolling resistance and handling predictors as well as optimized abrasion behavior and good processability (processability) result.

[0103] Silanes B of formula BI) may be preferred: (EtO) 3 Si-(CH 2 )-Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 2 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 3 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 4 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 5 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 6 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 7 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 8 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 9 -Si(OEt) 3 , (EtO) 3 Si-(CH 2 ) 10 -Si(OEt) 3 .

[0104] According to a preferred embodiment of the invention, the silane B has the following structure according to formula B-II): B-II) (EtO) 3 Si-(CH 2 ) 8 -Si(OEt) 3 .

[0105] It is particularly surprising that the combination of a silane A according to formula AI and / or A-XI, preferably a silane according to formula A-XII) or A-XIII), with a silane B according to formula BI), preferably a silane according to formula B-II), leads to a synergistic effect with regard to abrasion behavior, rolling resistance predictors, and handling predictors. A corresponding comparative mixture from the prior art does not exhibit this effect.

[0106] It is also conceivable that the rubber mixture according to the invention contains a mixture of two silanes of formula BI), such as, for example, B-II), with another silane of formula BI). The total amount of silanes B contained, which fall under formula BI), is in any case 0.5 to 30 phf, preferably 0.5 to 20 phf, particularly preferably 0.5 to 10 phf.

[0107] According to an advantageous development of the invention, the amount of silanes B contained is at least 0.7 phf.

[0108] According to a further advantageous development of the invention, the amount of silanes B contained is at least 1.0 phf.

[0109] According to a further advantageous development of the invention, the amount of silanes B contained is at least 2.5 phf.

[0110] The preferred minimum quantities also apply if only one type B silane is included.

[0111] In particular, the preferred and particularly preferred quantities and further developments or embodiments result in good processability and very good properties with regard to rolling resistance and handling predictors as well as optimized abrasion behavior.

[0112] The molar ratio of silanes A to silanes B present is particularly preferably 20:80 to 85:15, preferably 30:70 to 85:15, particularly preferably 40:60 to 85:15, very particularly preferably 50:50 to 85:15, in particular, for example, 66.6:33.3 (and thus 2:1).

[0113] The silanes A and / or B 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 A and / or B contained according to the invention can be applied to a silica, whereby the bonding can be physical or chemical.

[0114] Silanes A and B can be applied separately to silica and then these silicas can be added to the mixture, or silanes A and B can be applied together to a silica.

[0115] The application of the silanes A and / or B contained in the invention to silica reduces, for example, the emission of volatile by-products such as ethanol when using ethoxy-substituted silanes (R 1< = ethoxy).

[0116] According to an advantageous embodiment of the invention, the silane(s) A and the silane(s) B are mixed together before being added to the rubber mixture.

[0117] This means that silane only needs to be added once, so only one dosage form is necessary.

[0118] The silanes can be mixed in the absence of air. The silanes can be mixed in a protective gas atmosphere, for example, under argon or nitrogen, preferably under nitrogen.

[0119] The mixing of the silanes can be carried out at atmospheric pressure, elevated pressure, or reduced pressure. Preferably, the mixing of the silanes can be carried out at atmospheric pressure. Elevated pressure can be a pressure of 1.1 bar to 100 bar, preferably from 1.1 bar to 50 bar, more preferably from 1.1 bar to 10 bar, and most preferably from 1.1 to 5 bar. Reduced pressure can be a pressure of 1 mbar to 1000 mbar, preferably from 250 mbar to 1000 mbar, more preferably from 500 mbar to 1000 mbar.

[0120] The mixing of the silanes can be carried out between 20°C and 100°C, preferably between 20°C and 50°C, particularly preferably between 20°C and 30°C.

[0121] The silanes can be mixed in a solvent, for example, methanol, ethanol, propanol, butanol, cyclohexanol, N,N-dimethylformamide, dimethyl sulfoxide, pentane, hexane, cyclohexane, heptane, octane, decane, toluene, xylene, acetone, acetonitrile, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloroethane, tetrachloroethylene, diethyl ether, methyl tert-butyl ether, methyl ethyl ketone, tetrahydrofuran, dioxane, pyridine, or methyl acetate, or a mixture of the aforementioned solvents. The silanes are preferably mixed without a solvent.

[0122] Furthermore, it is conceivable that the rubber mixture according to the invention contains at least one further silane coupling agent which is not a silane A or a silane B.

[0123] 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.

[0124] 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 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 zinc oxide and fatty acids (e.g. stearic acid) and / or other activators, such as zinc complexes such as zinc ethylhexanoate, c) waxes, d) hydrocarbon resins, such as, in particular, tackifying resins, e) mastication aids, such as 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.

[0125] 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.

[0126] The plasticizer is preferably selected from the group consisting of the above-mentioned plasticizers.

[0127] The plasticizer is particularly preferably selected from the group consisting of hydrocarbon resins, liquid polymers and mineral oils.

[0128] 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.

[0129] 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.

[0130] According to a preferred embodiment of the invention, the rubber mixture contains at least one liquid polymer as a plasticizer.

[0131] According to a preferred embodiment of the invention, the rubber mixture contains at least one hydrocarbon resin as a plasticizer.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] The proportion of the total amount of other additives is 3 to 150 phr, preferably 3 to 100 phr and particularly preferably 5 to 80 phr.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] Sulfur and / or other sulfur donors, as well as one or more accelerators, are added to the rubber compound in the final mixing step. The accelerator is selected from the group consisting of thiazole accelerators, mercapto accelerators, sulfenamide accelerators, thiocarbamate accelerators, thiuram accelerators, thiophosphate accelerators, thiourea accelerators, xanthate accelerators, and / or guanidine accelerators.

[0140] 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).

[0141] 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

[0142] 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.

[0143] 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.

[0144] 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.

[0145] According to an advantageous development of the invention, several accelerators are used. Preferably, a sulfenamide accelerator, particularly preferably CBS, 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, and most preferably 1 to 2.5 phr.

[0146] 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.

[0147] The present invention further provides a process for producing the sulfur-crosslinkable rubber mixture according to the invention, in which a base mixture containing all components except the vulcanization system is first prepared in one or more mixing stages. The finished mixture is produced by adding the vulcanization system in a final mixing stage. The finished mixture is further processed, for example, by an extrusion process or calendering, and formed into the appropriate shape. Further processing then takes place by vulcanization, whereby sulfur crosslinking occurs due to the vulcanization system added within the scope of the present invention.

[0148] According to an advantageous embodiment of the process according to the invention, the silane(s) A and the silane(s) B are mixed together before being added to the rubber mixture, preferably in the stated molar ratios A to B and under the above-mentioned conditions including all described embodiments.

[0149] According to an advantageous embodiment of the process according to the invention, the silanes A and / or B are applied to a silica, wherein the bonding can be physical or chemical, and are added to the rubber mixture in this form, preferably in a basic mixing stage.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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 and / or different reinforcements and one or more further layers of the same and / or a different rubber mixture.

[0154] The invention will now be explained in more detail using comparative and exemplary embodiments, which are summarized in Table 1.

[0155] The quantity of silanes in phf refers to 46 phr of silica.

[0156] Otherwise, the compound was produced according to the process customary in the rubber industry under standard conditions in three stages in a laboratory mixer with a volume of 300 milliliters to 3 liters. In the first mixing stage (basic mixing stage), all components except the vulcanization system (sulfur and vulcanization-influencing substances) were mixed for 200 to 600 seconds at 145 to 165 °C, with target temperatures of 152 to 157 °C. In the second stage, the mixture from stage 1 was mixed again, a so-called remill. The finished compound was created by adding the vulcanization system in the third stage (final mixing stage), which was mixed for 180 to 300 seconds at 90 to 120 °C.

[0157] Test specimens were produced from all mixtures by vulcanization after t 95 to t 100 (measured on a moving die rheometer according to ASTM D 5289-12 / ISO 6502) under pressure at 160°C to 170°C and with these test specimens, material properties typical for the rubber industry were determined using the test methods specified below. Mooney viscosity (Visk.) (ML 1+4) 100°C according to ASTM D 1646 (2004) Loss factor tan δ (10%) from RPA (= English "rubber process analyzer") based on ASTM D6601 from the second strain sweep at 1 Hz and 70°C Shore hardness at room temperature (RT) according to ISO 868, DIN 53 505 Rebound resilience at 70°C according to DIN 53 512 and ISO 4662 Tensile stress at 300% elongation at room temperature (M 300 RT) and 70°C (M 300 70°C) according to DIN 53 504 Abrasion at room temperature according to DIN / ISO 4649 Substances used:

[0158] a) NR: Natural rubber Standard Indonesian Rubber b) IR: Synthetic polyisoprene, SKI-3 c) SSBR d) BR: Butadiene rubber, Buna CB 25 e) Silica: Zeosil 1165 MP, Solvay f) Silane A: according to formula A-XII): NXT-Silane 3-Octanoylthio-1-propyltriethoxysilane g) Silane B: according to formula B-II): Bistriethoxysilyloctane, Gelest h) Other ingredients: 3 phr zinc oxide, 2 phr stearic acid, 2 phr antiozone wax, 2.5 phr anti-aging agent (consists of 1 phr DTPD and 1.5 phr 6-PPD), 2 phr accelerator (consists of 1 phr DPG and 1 phr TBBS); 1.65 phr sulfur

[0159] As can be seen from Table 1, with rubber mixtures containing the inventive combination of silica and the silanes A and B and a high amount of NR or IR, namely the inventive mixtures E1 and E2, particularly low values ​​for DIN abrasion and thus better abrasion performance, and particularly high values ​​for M 300 at RT and 70 °C as indications of stiffness and thus improved handling indicators and particularly high values ​​for rebound resilience at 70 °C and particularly low values ​​for Tan d (10%) and thus improved rolling resistance indicators compared to V1 and V2 or V3 and V4 are achieved.

[0160] These surprising advantages do not occur in compounds with 100 phr SSBR or a polymer blend (of 10 phr NR, 72 phr SSBR and 18 phr BR) to the extent that can be seen in the compounds V6 vs. V5 and V7 or V9 vs. V8 and V10.

[0161] With the rubber mixture according to the invention, a further improvement in the property profile, including abrasion behavior, rolling resistance behavior and handling behavior, in particular through stiffness, is achieved compared to the prior art. Table 1 Components Unit V1 E1 V2 V3 E2 V4 V5 V6 V7 V8 V9 V10 NR a)< phr 100 100 100 - - - - - - 10 10 10 IR b)< phr - - - 100 100 100 - - - - - - SSBR c)< phr - - - - - - 100 100 100 72 72 72 BR d)< phr - - - - - - - - - 18 18 18 Silica e)< phr 46 46 46 46 46 46 46 46 46 46 46 46 Silane A f)< phf 10,2 10,2 - 10,2 10,2 - 10,2 10,2 - 10,2 10,2 - Silane B g)< phf - 6,2 6,2 - 6,2 6,2 - 6,2 6,2 - 6,2 6,2 Other ingredients h)< phr 13,2 13,2 13,2 13,2 13,2 13,2 13,2 13,2 13,2 13,2 13,2 13,2 Characteristics Mooney (ML1+4) ME 81 76 87 63 58 69 87 72 89 77 69 84 Tan d (10%) 0,092 0,077 0,121 0,084 0,066 0,117 0,123 0,101 0,168 0,108 0,092 0,158 Shore hardness RT Sh A 54 57 54 56 58 55 59 60 58 60 61 58 Check back 70 °C % 71 73 67 67 70 60 60 60 54 62 63 54 M 300 RT MPa 6,9 7,5 4,5 4,8 5,5 2,7 5,9 5,8 3,2 5,2 5,5 2,6 M 300 70 °C MPa 4,5 5 3,1 3,5 4,2 2,1 5,4 5,5 3 4,9 5,1 2,3 DIN abrasion mm 3< 129 127 187 153 140 174 162 172 217 119 142 193

Claims

1. Sulfur-crosslinkable rubber mixture containing at least the following constituents: - 80 to 100 phr of at least one polyisoprene selected from natural and synthetic polyisoprene; - 10 to 500 phr of at least one silica; and - 1 to 30 phf of at least one silane A having the general empirical formula A-I) and / or A-XI)         A-I)     (R1)oSi-R2-(S-R3)q-Sx-(R3-S)q-R2-Si(R1)o;         A-XI)     (R1)oSi-R2-(S-R3)s-S-X; and - 0.5 to 30 phf of at least one silane B having the general empirical formula BI)         B-I)     (R1)oSi-R4-Si(R1)o wherein o may be 1 or 2 or 3 and the radicals R1 may be identical or different and are selected from C1-C10-alkoxy groups, C6-C20-phenoxy groups, C2-C10-cyclic dialkoxy groups, C2-C10-dialkoxy groups, C4-C10-cycloalkoxy groups, C6-C20-aryl groups, C1-C10-alkyl groups, C2-C20-alkenyl groups, C2-C20-alkynyl groups, C7-C20-aralkyl groups, halides or alkyl polyether group -O-(R6-O)r-R7, wherein the radicals R6 are identical or different and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic / aromatic divalent C1-C30-hydrocarbon groups, r is an integer from 1 to 30 and the radicals R7 are unsubstituted or substituted, branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl groups, or two R1 correspond to a dialkoxy group having 2 to 10 carbon atoms, in which case o is < 3, or two or more silanes of formulae A-I) and / or A-XI) and / or B-I) may be bridged via radicals R1 or by condensation; and with the proviso that in the formulae A-I) and A-XI) and B-I) in each (R1)oSi group at least one R1 is selected from the aforementioned options where this R1 i) is bonded to the silicon atom via an oxygen atom or ii) is a halide; and wherein the radicals R2, R3 and R4 in each molecule and within a molecule may be identical or different and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic / aromatic divalent C1-C30 hydrocarbon groups which may also contain heteroatoms, such as oxygen (O) and / or nitrogen (N), and functional groups, such as urea groups and / or amide groups; and wherein x is an integer from 2 to 10 and q is 0 or 1 or 2 or 3; and wherein s is 0 or 1 or 2 or 3; and X is a hydrogen atom or a -C(=O)-R8 group, wherein R8 is selected from hydrogen, C1-C20-alkyl groups, C6-C20-aryl groups, C2-C20-alkenyl groups and C7-C20-aralkyl groups.

2. Sulfur-crosslinkable rubber mixture according to Claim 1, characterized in that it contains at least one silane having the general empirical formula A-XI), wherein s is preferably 0.

3. Sulfur-crosslinkable rubber mixture according to either of the preceding claims, characterized in that X is a -C(=O)-R8 group, wherein R8 is a C1-C20-alkyl group, preferably a C1-C10-alkyl group.

4. Sulfur-crosslinkable rubber mixture according to any of the preceding claims, characterized in that R2 is an alkylene group having 2 or 3 carbon atoms.

5. Sulfur-crosslinkable rubber mixture according to any of the preceding claims, characterized in that R4 is an alkylene group having 5 to 10 carbon atoms, preferably 8 carbon atoms.

6. Sulfur-crosslinkable rubber mixture according to any of the preceding claims, characterized in that the silane A-XI) has the following structure according to formula A-XII):         A-XII)     (EtO)3Si-(CH2)3-S-C(=O)(CH2)6-CH3.

7. Sulfur-crosslinkable rubber mixture according to any of the preceding claims, characterized in that the silane B has the following structure according to formula B-II):         B-II)     (EtO)3Si-(CH2)8-Si(OEt)3.

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

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

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