Sulfur-crosslinkable rubber compound, vulcanizate and vehicle tires

Abstract

Sulfur-curable rubber compound containing at least the following components: - 10 to 90 phr of at least one butadiene rubber B, which is amino-functionalized and has a cis content of less than 50%, and 10 to 90 phr of at least one further diene rubber, wherein the sulfur-crosslinkable rubber mixture contains at least 10 phr of at least one polyisoprene as a further diene rubber, and - 25 phr or more of at least one carbon black A, which has an iodine adsorption number according to ASTM D 1510 of 85 to 180 g / kg and a DBP number according to ASTM D 2414 of 100 to 200 ml / 100 g.

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] EP 2289990 A1 discloses a rubber mixture containing equal amounts of silica and an ASTM carbon black of type N 550, as well as functionalized polymers. Among other things, the use of 50 phr of amino-functionalized polybutadiene instead of 50 phr of unfunctionalized polybutadiene is disclosed. US 2010 / 0152369 A1 discloses a method for producing a diene-based (co)polymer, in which a corresponding (co)polymer is modified using a metal halide, as well as the use of such (co)polymers in rubber mixtures.

[0004] WO2015043901A1 discloses a rubber mixture containing amino-functionalized SSBR (solution-polymerized styrene-butadiene rubber) and carbon black.

[0005] The present invention is based on the object of providing a sulfur-crosslinkable rubber mixture on the basis of the prior art which has a further improvement in rolling resistance, wherein the other properties remain at least at a comparable level or are even improved.

[0006] The object is achieved according to the invention in that the sulfur-crosslinkable rubber mixture contains at least the following components: - 10 to 90 phr of at least one butadiene rubber B which is amino-functionalized and has a cis content of less than 50%, and 10 to 90 phr of at least one further diene rubber, wherein the sulfur-crosslinkable rubber mixture contains as further diene rubber at least 10 phr of at least one polyisoprene, and - 25 phr or more of at least one carbon black A, which has an iodine adsorption number according to ASTM D 1510 of 85 to 180 g / kg and a DBP number according to ASTM D 2414 of 100 to 200 ml / 100 g.Surprisingly, it has been found that the combination of the above-mentioned components, in particular the combination of the butadiene rubber B with the carbon black A, achieves a further improvement in the rolling resistance predictors, with other properties remaining at a good level or even being improved, resulting in improved rolling resistance behavior, particularly when used in vehicle tires.

[0007] A further subject of the present invention is a vulcanizate of at least one rubber mixture according to the invention.

[0008] 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 and / or the sidewall. Particularly preferably, the vehicle tire comprises the at least one vulcanizate at least in the tread.

[0009] The vulcanizate according to the invention and the vehicle tire according to the invention are characterized by an improvement in rolling resistance.

[0010] 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.

[0011] 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).

[0012] 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.

[0013] 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.

[0014] 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.

[0015] The term phr (parts per hundred parts of rubber by weight) used in this document is the standard quantity 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 compound with a molecular weight Mw according to GPC of greater than 20,000 g / mol.

[0016] According to the invention, the rubber mixture contains at least one butadiene rubber B which is amino-functionalized and whose cis content is less than 50%.

[0017] In the context of the present application, "amino-functionalized" means that the rubber carries one or more amino groups at at least one chain end of each polymer chain. In particular, both chain ends of each polymer chain can also carry one or more amino groups.

[0018] It is conceivable that not all polymer chains contain an amino group. The weight fraction of amino-functionalized polymer chains is preferably 30 to 100%, particularly preferably 50 to 100%, and most preferably 70 to 100%.

[0019] Amino groups (-NR2) are known to have two additional residues (R) on the nitrogen atom in addition to the bond to the respective main chain of a hydrocarbon compound. If both additional residues are hydrogen atoms (R=H), the group is a primary amino group. If one additional residue is a hydrogen atom and the other is not a hydrogen atom, the group is a secondary amino group. If both residues are not hydrogen atoms, the group is a tertiary amino group.

[0020] In the context of the present invention, in principle all amino groups are conceivable as functionalization of the butadiene rubber B.

[0021] According to an advantageous embodiment of the invention, the amino groups are tertiary amino groups. This results in health and environmental benefits, as the formation of harmful substances such as nitrosamines is more effectively prevented.

[0022] Butadiene rubber (BR) is also known to the expert as polybutadiene. It is known that polybutadienes can be differentiated, among other things, by their cis content, with polybutadienes with a cis content greater than or equal to 90% being referred to as high-cis types, and polybutadienes with a cis content less than 90% being referred to as low-cis types. An example of a low-cis polybutadiene is Li-BR (lithium-catalyzed butadiene rubber) with a cis content of 20 to 50%.

[0023] The cis content in percent refers to 100% of a polymer chain. The cis content is determined according to 13C-NMR measurements (sample extraction with acetone; solvent CDCl3).

[0024] The butadiene rubber B contained in the invention has a cis content of less than 50%.

[0025] According to advantageous embodiments of the invention, the cis content of the amino-functionalized butadiene rubber B is 30 to 50%.

[0026] The butadiene rubber B contained in the invention is produced in particular by anionic polymerization, which makes more chain ends available for functionalization compared to other production processes. This results in the advantages of the invention to a particularly high degree.

[0027] According to an advantageous embodiment of the invention, the rubber mixture contains 100 phr of the amino-functionalized butadiene rubber B.

[0028] Butadiene rubber is known to be a diene rubber, which means that the rubber mixture according to the invention is sulfur-crosslinkable.

[0029] 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.

[0030] According to the invention, the rubber mixture contains 10 to 90 phr of the at least one amino-functionalized butadiene rubber B having a cis content of less than 50% and 10 to 90 phr of at least one further diene rubber, wherein it contains at least 10 phr of at least one polyisoprene as further diene rubber.

[0031] The diene rubber is preferably selected from the group consisting of natural polyisoprene (NR) and / or synthetic polyisoprene (IR) and / or epoxidized polyisoprene (ENR) and / or butadiene rubber (BR) and / or butadiene-isoprene rubber and / or solution-polymerized styrene-butadiene rubber (SSBR). and / or emulsion-polymerized styrene-butadiene rubber (ESBR) and / or styrene-isoprene rubber and / or liquid rubbers having a molecular weight Mw 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.

[0032] 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.

[0033] In this case, the mixture compositions known to the person skilled in the art for these rubbers - which are special with regard to fillers, plasticizers, vulcanization systems and additives - are preferred.

[0034] As stated above, in the case of a blend of the butadiene rubber B with at least one other diene rubber, at least 10 phr of at least one polyisoprene is contained.

[0035] 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% 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 a cis-1,4-polyisoprene in which the cis-1,4 content in the natural rubber is greater than 99%.

[0036] Furthermore, a mixture of one or more natural polyisoprenes with one or more synthetic polyisoprene(s) is also conceivable.

[0037] According to a preferred embodiment of the invention, the rubber mixture contains at least 10 phr of at least one natural polyisoprene (NR).

[0038] The rubber mixture according to the invention can thus contain, for example, 90 phr of at least one butadiene rubber B and 10 phr of at least one polyisoprene, preferably 10 phr of NR.

[0039] According to a further example, the rubber mixture according to the invention can contain 80 phr of at least one butadiene rubber B and 20 phr of at least one polyisoprene, preferably 20 phr of NR.

[0040] According to a further example, the rubber mixture according to the invention can contain 40 to 60 phr of the at least one butadiene rubber B and 60 to 40 phr of at least one polyisoprene, preferably NR; preferably, no third rubber is present, so that the sum of the butadiene rubber B and polyisoprene present is 100 phr. For example, the rubber mixture according to the invention contains 50 phr of the at least one butadiene rubber B and 50 phr of polyisoprene, preferably 50 phr of natural rubber.

[0041] According to advantageous embodiments of the invention, the rubber mixture according to the invention can contain less than 90 phr of the at least one butadiene rubber B and 10 phr of at least one polyisoprene, preferably 10 phr of NR, as well as at least one third diene rubber, the sum of the rubber quantities also being 100 phr by definition.

[0042] The third diene rubber is preferably selected from the group consisting of SSBR, ESBR and BR, i.e. further butadiene rubber which is not butadiene rubber B according to the invention.

[0043] The other BR is in particular standard high-cis BR, which is produced, for example, using Nd catalysts (neodymium).

[0044] According to advantageous embodiments, the rubber mixture contains 10 to 60 phr of the at least one butadiene rubber B.

[0045] The rubber mixture according to the invention contains 25 phr or more of at least one carbon black A as filler, wherein the carbon black A has an iodine adsorption number according to ASTM D 1510 of 85 to 180 g / kg and a DBP number according to ASTM D 2414 of 100 to 200 ml / 100 g.

[0046] The carbon black A contained in the invention differs from carbon blacks such as N 550, which are known from amino-functionalized BR-containing rubber mixtures from the prior art, in terms of the specified surface and structural parameters.

[0047] Surprisingly, the combination according to the invention results in a reduction of the so-called Payne effect and thus improved damping behavior and thus improved rolling resistance behavior, while at the same time maintaining a very good level of the other physical properties of the rubber mixture, compared to a rubber mixture containing carbon black N 550 and amino-functionalized BR.

[0048] According to particularly advantageous embodiments, the at least one carbon black A has an iodine adsorption number according to ASTM D 1510 of 100 to 180 g / kg.

[0049] According to particularly advantageous embodiments, the at least one carbon black A has a DBP number according to ASTM D 2414 of 110 to 200 ml / 100 g.

[0050] The rubber mixture particularly preferably contains at least one carbon black A which has an iodine adsorption number according to ASTM D 1510 of 110 to 180 g / kg, preferably 110 to 150 g / kg, particularly preferably 110 to 140 g / kg, and a DBP number according to ASTM D 2414 of 110 to 180 ml / 100 g, preferably 110 to 160 ml / 100 g, particularly preferably 110 to 150 ml / 100 g.

[0051] Particularly preferably, and for example, the rubber mixture contains carbon blacks of ASTM types N 121 and / or N 220.

[0052] This surprisingly results in a significant reduction in the Payne effect in a rubber mixture containing amino-functionalized BR, starting from a rubber mixture containing a standard Nd-BR. The same reduction in the Payne effect is not found with a carbon black of ASTM type N 550. The amount of the at least one carbon black A is preferably 25 to 100 phr, more preferably 30 to 100 phr, again preferably 35 to 70 phr, and according to a very particularly preferred embodiment, 45 to 60 phr.

[0053] The quantity of at least one carbon black A is to be understood as the total quantity in the case of two or more carbon blacks of type A.

[0054] Furthermore, the rubber mixture may contain other carbon blacks known in the art that do not contribute to the amount of carbon black of type A. Other carbon blacks may be added as additional fillers, but preferably in comparatively small amounts, such as 0.1 to 5 phr.

[0055] However, it is also conceivable that substances such as silane coupling agents coated on carbon black are added to the rubber mixture.

[0056] The rubber mixture according to the invention may contain further fillers, for example in amounts of 0.1 to 50 phr.

[0057] Other reinforcing fillers include, in particular, silicas, which are known as fillers for use in rubber compounds for vehicle tires.

[0058] 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”.

[0059] 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).

[0060] Zinc oxide is not considered a filler in the context of the present invention.

[0061] Preferably, the rubber mixture according to the invention contains carbon black as the sole filler or as the main filler, meaning that the amount of carbon black is significantly greater than the amount of any other fillers present. If a further filler is present in addition to carbon black, this is preferably silica.

[0062] According to an advantageous embodiment of the invention, the rubber mixture according to the invention contains carbon black and silica, such as 30 to 100 phr of carbon black in combination with 0.1 to 20 phr of silica; preferably 0.1 to 10 phr, particularly preferably 3 to 10 phr of silica.

[0063] The silica can be any of the types of silica known to those 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 that has a nitrogen surface area (BET surface area) (according to DIN ISO 9277 and DIN 66132) of 35 to 400 m². 2 / g, preferably from 35 to 350 m 2 / g, particularly preferably from 85 to 320 m 2 / g and most preferably from 120 to 235 m 2 / g, and a CTAB surface area (according to ASTM D 3765) of 30 to 400 m 2 / g, preferably from 30 to 330 m 2 / g, particularly preferably from 80 to 300 m 2 / g and most preferably from 110 to 230 m 2 / g. 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.

[0064] The terms “silicic acid” and “silica” are used synonymously in the present invention.

[0065] 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) Anti-aging agents 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 adhesive resins e) mastication aids such as 2,2'-dibenzamidodiphenyl disulfide (DBD) and f) Processing aids, in particular fatty acid esters and metal soaps, such as zinc soaps and / or calcium soaps g) Plasticizers h) Activators and / or agents for the binding of fillers, in particular carbon black or silica, such as S-(3-aminopropyl)thiosulphuric acid and / or its metal salts (binding to carbon black) and silane coupling agents (binding to silica).

[0066] The silane coupling agents can be any type known to the person skilled in the art.

[0067] Furthermore, one or more different silane coupling agents can be used in combination. The rubber compound can thus contain a mixture of different silanes.

[0068] The silane coupling agents react with the surface silanol groups of the silica or other polar groups during the mixing of the rubber or rubber compound (in situ) or even before the addition of the filler to the rubber in the sense of a pretreatment (premodification).

[0069] Coupling agents known from the prior art are bifunctional organosilanes that possess at least one alkoxy, cycloalkoxy, or phenoxy group as a leaving group on the silicon atom and that have, as another functionality, a group that, after cleavage, can enter into a chemical reaction with the double bonds of the polymer. The latter group can be, for example, the following chemical groups: -SCN, -SH, -NH2 or -S x - (with x = 2 to 8).

[0070] For example, 3-mercaptopropyltriethoxysilane, 3-thiocyanatopropyltrimethoxysilane, or 3,3'-bis(triethoxysilylpropyl)polysulfides with 2 to 8 sulfur atoms, such as 3,3'-bis(triethoxysilylpropyl)tetrasulfide (TESPT), the corresponding disulfide (TESPD), or mixtures of sulfides with 1 to 8 sulfur atoms with varying contents of the various sulfides, can be used as silane coupling agents. TESPT can also be added, for example, as a mixture with carbon black (trade name X50S® from Evonik).

[0071] Blocked mercaptosilanes, such as those known from WO 99 / 09036, can also be used as silane coupling agents. Silanes such as those described in WO 2008 / 083241 A1, WO 2008 / 083242 A1, WO 2008 / 083243 A1, and WO 2008 / 083244 A1 can also be used. Examples of suitable silanes include those marketed under the name NXT in various versions by Momentive, USA, or those marketed under the name VP Si 363® by Evonik Industries.

[0072] 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.

[0073] The plasticizer is preferably selected from the group consisting of the above-mentioned plasticizers.

[0074] The plasticizer is particularly preferably selected from the group consisting of hydrocarbon resins, liquid polymers and mineral oils.

[0075] 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.

[0076] 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.

[0077] According to a preferred embodiment of the invention, the rubber mixture contains at least one liquid polymer as a plasticizer.

[0078] According to a preferred embodiment of the invention, the rubber mixture contains at least one hydrocarbon resin as a plasticizer.

[0079] 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 linking 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 C5 monomers, other unsaturated compounds that can be cationically polymerized, containing aromatics and / or terpenes and / or alkenes and / or cycloalkenes.

[0080] In a preferred embodiment of the invention, the hydrocarbon resin is selected from the group consisting of aliphatic C5 resins and hydrocarbon resins of alpha-methylstyrene and styrene.

[0081] 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.

[0082] 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.

[0083] 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 m 2 / g. However, it can also be a zinc oxide with a BET surface area of ​​10 to 100 m 2 / g, such as so-called “nano-zinc oxides”, can be used.

[0084] 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.

[0085] 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.

[0086] 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).

[0087] 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

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] In addition, vulcanization retarders such as CTP (N-(cyclohexylthio)phthalimide) may be present in the rubber compound.

[0093] The terms “vulcanized” and “crosslinked” are used synonymously in the context of the present invention.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] The invention will now be explained in more detail using comparative and exemplary embodiments, which are summarized in the following tables.

[0099] The comparison mixtures are marked with V, the mixtures according to the invention are marked with E.

[0100] Otherwise, the compound was produced according to the procedure 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, target temperatures of 150 to 160 °C. In the second stage, the mixture from the first mixing stage was mixed again. By adding the vulcanization system in the third stage (final mixing stage), the final mixture was produced, which was mixed for 180 to 300 seconds at 90 to 120 °C. Test specimens were made from all mixtures by vulcanization after t 95(measured on a moving die rheometer according to ASTM D 5289-12 / ISO 6502) under pressure at 160°C and with these test specimens, material properties typical for the rubber industry were determined using the test methods specified below. • Shore A hardness at room temperature using a durometer according to DIN ISO 7619-1 • Tensile strength and stress value at 300% elongation (modulus 300, M300) at room temperature (RT) according to DIN 53 504 • Rebound resilience at 70 °C according to ISO 4662 or ASTM D1054 • Measurements on the Payne effect: Difference E'(0.15%) - E'(8%): ​​dynamic storage modulus E' at 55 °C from dynamic-mechanical measurement according to DIN 53 513, strain sweep at 0.15% and 8% strain • Abrasion at room temperature according to DIN / ISO 4649 Substances used from Table 1: a) Nd-BR, high-cis b) Butadiene rubber B, amino-functionalized: BR500, JSR Corporation c) Silica VN3, Evonik d) 3 phr aromatic hydrocarbon resin, 5 phr plasticizer such as TDAE oil, 6 phr anti-aging agent and ozone protection wax, 3 phr zinc oxide, 2 phr stearic acid, 1.5 phr TESPT 50 wt% on carbon black (ie 0.75 phr TESPT and 0.75 phr carbon black) e) CBS

[0101] As can be seen from Table 1, the combination of a carbon black A with a butadiene rubber B (amino-functionalized and cis content less than 50%) leads to a significant reduction in the Payne effect compared to rubber mixtures from the prior art, which is evident from the greater change in the difference E'(0.15%) - E'(8%) of the respective inventive mixture containing the carbon blacks N 121 or N 220. This difference changes more significantly from V2 to E1 and from V3 to E2 than from V1 to V4.

[0102] At the same time, with the carbon blacks N 121 and N 220 in the inventive mixtures E1 and E2, a significant improvement in the rolling resistance predictor rebound resilience at 70 °C is evident compared to V2 and V3, while the change from V1 to V4 with the carbon black N 550 is only slight.

[0103] At the same time, the rubber mixtures E1 and E2 according to the invention have a better abrasion level compared to V4.

[0104] In addition, the rubber mixtures E1 and E2 according to the invention have improved tensile strengths.

[0105] Thus, with the mixtures according to the invention it is possible to further improve the rolling resistance behavior in a rubber mixture, while the other properties remain at a very good level.

[0106] A vehicle tire according to the invention, which has at least one vulcanizate of the rubber mixture according to the invention in at least one component, in particular the tread, is optimized with regard to rolling resistance with regard to the overall level of the other requirements of durability, abrasion and handling. Table 1 Components Unit V1 V2 V3 V4 E1 E2 NR TSR phr 50 50 50 50 50 50 BR a) phr 50 50 50 - - - Amino BR b) phr - - - 50 50 50 Carbon black N 550 phr 55 - - 55 - - Soot N 121 phr - 55 - - 55 - Carbon black N 220 phr - - 55 - - 55 Silica c) phr 6,0 6,0 6,0 6,0 6,0 6,0 additives d) phr 20,5 20,5 20,5 20,5 20,5 20,5 accelerator e) phr 2,0 2,0 2,0 2,0 2,0 2,0 sulfur phr 1,1 1,1 1,1 1,1 1,1 1,1 CTP phr 0,15 0,15 0,15 0,15 0,15 0,15 Characteristics Shore hardness RT Shore A 64 68,4 67 64 67,4 66,4 Rebound load: 70 °C % 70,3 57,4 57,5 70,9 60,7 60,5 Module 300 MPa 14 13,5 12,2 14,9 14,4 12,8 Tensile strength MPa 17,6 19,9 18,6 17,2 22 20,8 E'(0.15%) - E'(8%) MPa 3,4 9,3 9,5 2,9 8,2 7,4 DIN abrasion mm 3 87 56 61 88 65 69

Claims

[1] Sulphur-crosslinkable rubber mixture containing at least the following components: - 10 to 90 phr of at least one butadiene rubber B which is amino-functionalized and has a cis content of less than 50%, and 10 to 90 phr of at least one further diene rubber, wherein the sulfur-crosslinkable rubber mixture contains as further diene rubber at least 10 phr of at least one polyisoprene, and - 25 phr or more of at least one carbon black A which has an iodine adsorption number according to ASTM D 1510 of 85 to 180 g / kg and a DBP number according to ASTM D 2414 of 100 to 200 ml / 100 g. [2] Sulphur-crosslinkable rubber mixture according to claim 1, characterized by that it contains at least 10 phr of at least one natural polyisoprene. [3] Sulphur-crosslinkable rubber mixture according to one of the preceding claims, characterized bythat the at least one carbon black A has an iodine adsorption number according to ASTM D 1510 of 100 to 180 g / kg. [4] Sulphur-crosslinkable rubber mixture according to one of the preceding claims, characterized by that the at least one carbon black A has a DBP number according to ASTM D 2414 of 110 to 200 ml / 100 g. [5] Vulcanizate obtained by the sulfur vulcanization of at least one rubber mixture according to one of claims 1 to 4. [6] Vehicle tires, characterized by that it has at least one vulcanizate according to claim 5 in at least one component. [7] Vehicle tyre according to claim 6, characterized by that the component is a tread and / or a sidewall. [8] Use of a rubber mixture according to one of claims 1 to 4 for the production of a technical rubber article, such as bellows, conveyor belts, air springs, belts, straps or hoses, as well as shoe soles.