Sulfur-crosslinkable rubber mixture, vulcanisate of the rubber mixture, and vehicle tyre

Abstract

The invention relates to a sulfur-crosslinkable rubber mixture, to the vulcanisate of the rubber mixture, and to a vehicle tyre. The rubber mixture contains at least the following constituents: a) 50 to 100 phr of at least one polyisoprene, b) 0 to 50 phr of at least one butadiene rubber, where the butadiene rubber has been functionalized for binding of silica, c) 20 to 100 phr of at least one silicon dioxide of high surface area, d) 1 to 30 phr of silanes selected from at least two organosilicon compounds.

Description

[0001] Description

[0002] Sulfur-curable rubber compound, vulcanizate of the rubber compound and vehicle tires

[0003] The invention relates to a sulfur-curable rubber compound, its vulcanizate, and a vehicle tire. Furthermore, the invention relates to the use of the sulfur-curable rubber compound.

[0004] The rubber composition of the tread largely determines the driving characteristics of a vehicle tire, especially a pneumatic tire. Similarly, the rubber compounds used in belts, hoses, and straps—particularly in areas subject to high mechanical stress—are essential for the stability and durability of these rubber products. Therefore, very high demands are placed on these rubber compounds used in pneumatic tires, belts, straps, and hoses.

[0005] There are conflicting objectives between most of the known tire characteristics such as wet grip, braking performance, handling behavior, rolling resistance, winter performance, abrasion behavior and wet braking performance, especially tearing properties.

[0006] The present invention was based on the objective of providing a rubber compound which, compared to the prior art, as published, for example, in DE 102017 221 232 A1 or WO 2023 104 252 A1, exhibits an overall improvement in the property profile encompassing rolling resistance behavior, abrasion behavior, in particular abrasion resistance, and wet braking properties.

[0007] Surprisingly, the rubber compound, vulcanizate, and vehicle tire according to the invention achieve an improvement in the conflicting objectives of rolling resistance, abrasion resistance (especially wear resistance), and wet braking performance (especially wet grip). In particular, rolling resistance is improved. At the same time, the rubber compound exhibits good processability, especially miscibility and extrudability, so that the vulcanizate and vehicle tire according to the invention are also easy to process.

[0008] Thus, with the rubber compound, the vulcanizate and the vehicle tire according to the invention, an improvement is also achieved in the conflict of objectives between processability and the aforementioned properties, in particular rolling resistance behavior, abrasion behavior and wet braking behavior.

[0009] The invention encompasses all advantageous embodiments, which are reflected, inter alia, in the claims. In particular, the invention also encompasses embodiments resulting from the combination of different features, for example, components of the rubber compound, and different degrees of preference given to these features, such that a combination of a first feature designated as "preferred" or described within the framework of an advantageous embodiment with a further feature designated, for example, as "particularly preferred," is also encompassed by the invention.

[0010] The components of the sulfur-curable rubber compound according to the invention are described in more detail below. All information regarding the components of the rubber compound according to the invention, regardless of the degree of preference given to these features, also applies accordingly to the vulcanizate according to the invention, the vehicle tire according to the invention, and the use according to the invention.

[0011] The unit phr (parts per hundred parts of rubber by weight) used in this document is the standard unit of measurement for compound formulations in the rubber industry. The dosage of the parts by weight of the individual substances is measured in this document per 100 parts by weight of the total mass of all rubbers present in the mixture, with a molecular weight Mw of greater than 20,000 g / mol, using gel permeation chromatography (GPC) in accordance with ISO 13885-1. According to the invention, the rubber mixture contains at least one diene rubber from the group consisting of natural polyisoprene (NR) and synthetic polyisoprene (IR).

[0012] Diene rubbers are rubbers that are formed 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.

[0013] According to the invention, the rubber mixture further contains at least one diene rubber, which is a butadiene rubber (synonyms: BR, BR rubber, polybutadiene).

[0014] The butadiene rubber according to the invention is explicitly not one of the diene rubbers mentioned below, such as butadiene-isoprene rubber or styrene-butadiene rubber.

[0015] Other possible diene rubbers that may be present in smaller quantities in the mixture according to the invention are butadiene-isoprene rubber, styrene-butadiene rubber (SBR), in particular solution-polymerized styrene-butadiene rubber (SSBR) and emulsion-polymerized styrene-butadiene rubber (ESBR), styrene-isoprene rubber, halobutyl rubber, polynorbornene, isoprene-isobutylene copolymer, ethylene-propylene-diene rubber, nitrile rubber, chloroprene rubber, acrylate rubber, fluorocarbon rubber, silicone rubber, polysulfide rubber, epichlorohydrin rubber, styrene-isoprene-butadiene terpolymer, hydrogenated Acrylonitrile butadiene rubber and hydrogenated styrene butadiene rubber.

[0016] The mixture preferably does not include liquid rubbers, and in particular does not include rubbers that are liquid at room temperature and ambient pressure.

[0017] In particular, nitrile rubber, hydrogenated acrylonitrile butadiene rubber, chloroprene rubber, butyl rubber, halobutyl rubber, or ethylene propylene diene monomer rubber are used in the manufacture of technical rubber articles such as belts, straps, and hoses, and / or shoe soles. The preferred application is of the compound compositions known to those skilled in the art for these rubbers—specifically with regard to fillers, plasticizers, vulcanization systems, and additives.

[0018] The diene rubber according to the invention comprises 50 to 100 phr polyisoprene, preferably 55 to 85 phr polyisoprene, particularly preferably 60 to 80 phr, which is preferably natural polyisoprene (NR).

[0019] The diene rubber according to the invention further comprises 0 to 50 phr butadiene rubber (BR), preferably 10 to 40 phr, particularly preferably 15 to 25 phr butadiene rubber.

[0020] The combination of 50 to 100, preferably 55 to 85 phr, particularly preferably 60 to 80 phr polyisoprene, preferably natural polyisoprene (NR), and 0 to 50 phr, preferably 10 to 40 phr, particularly preferably 15 to 25 phr butadiene rubber (BR) solves the problem underlying the invention particularly well and the rubber mixture exhibits particularly optimal processability.

[0021] Preferably, the proportions of NR and BR add up to approximately 100 phr or exactly 100.00 phr.

[0022] In the event that the rubber mixture contains less than 100 phr of NR and BR, at least one further rubber, preferably at least one further diene rubber selected from the above list, is included, such that the sum of the contained rubbers by definition equals 100 phr.

[0023] The butadiene rubber (polybutadiene, BR) contained in the rubber compound according to the invention is preferably of the low-cis type. The so-called high-cis and low-cis types refer to polybutadienes with a cis content greater than or equal to 90 wt.% (weight %, high-cis type) and polybutadienes with a cis content less than 90 wt.% (low-cis type), respectively.

[0024] The polybutadienes used can be end-modified and / or functionalized along the polymer chains. The polybutadienes can be simply or multiply modified. Modifications can include hydroxy groups, ethoxy groups, epoxy groups, siloxane groups, amino groups, aminosiloxane, carboxy groups, phthalocyanine groups, and / or silane sulfide groups. Other modifications, also known as functionalizations, are also possible and are known to a qualified professional. Metal atoms may be part of such functionalizations.

[0025] The BR rubber used in the present rubber compound is a BR specifically functionalized for the bonding of silicon dioxide or silica, preferably having a glass transition temperature Tg below -70 °C, more preferably below -75 °C. The glass transition temperature Tg is preferably not colder than -110 °C, more preferably not colder than -100 °C, and more preferably not below -95 °C. A preferred glass transition temperature is between -85 °C and -95 °C or between -75 °C and -85 °C.

[0026] The BR rubber used in the present rubber compound is preferably of the low-cis type.

[0027] The chain ends of the BR rubber used in the present rubber compound are preferably functionalized for the attachment of silicas.

[0028] The BR rubber used in the present rubber compound is preferably not oil-extended.

[0029] The BR rubber used in the present rubber compound preferably has a weight-average molar mass Mw, measured by GPC (in accordance with ISO 13885-1), in the range of 200,000 to 2,000,000 g / mol, more preferably in the range of 250,000 to 1,000,000 g / mol, more preferably in the range of 300,000 to 750,000 g / mol, and more preferably between 300,000 and 600,000 g / mol. Several of the aforementioned BR rubbers may also be blended. Liquid BR rubbers are preferably omitted from the present rubber compound.

[0030] The terms “silicic acid”, “silica” and “silicon dioxide” are used synonymously within the scope of the present invention.

[0031] The BR rubber functionalized for silica is preferably mixed in the present rubber mixture with a high-surface-area silicon dioxide, as specified in more detail later.

[0032] The functionalized BR rubber can have several functionalizations and, for example, can also be functionalized for interaction with carbon black.

[0033] The combination results in an unexpectedly significant performance advantage for the rubber compound. This includes a marked improvement in rolling resistance, unexpectedly improved wet braking performance, and unexpectedly good abrasion resistance.

[0034] Examples of BR rubbers used in the present invention are, for example, BR511 from Eneos (Tg = -78 °C, functionalized, Mw = 361,000 g / mol, 37% trans content, 30% cis content, and 30% vinyl content, high silicon dioxide affinity) or KBR820 from KKPC (Tg = -92 °C, functionalized, 40.5% cis content and 12% vinyl content, high silicon dioxide affinity). The percentages given are weight percentages.

[0035] According to the invention, the rubber mixture contains as a further component 20 to 100 phr, preferably 30 to 70 phr, particularly preferably 40 to 60 phr, more preferably 45 to 55 phr of at least one silicon dioxide.

[0036] The at least one silicon dioxide has a mean nitrogen surface area (BET surface area) according to DIN ISO 9277 of at least 210 m² / g (square meters per gram), preferably 210 to 425 m² / g, more preferably 210 to 320 m² / g, and more preferably 265 to 320 m² / g. The at least one silicon dioxide preferably also has a mean CTAB surface area according to ASTM D 3765 of over 200 m² / g, more preferably 200 to 400 m² / g, more preferably 200 to 300 m² / g, and particularly preferably 245 to 300 m² / g.

[0037] The at least one silicon dioxide is preferably amorphous silicon dioxide, preferably precipitated silica, which is also referred to as precipitated silicon dioxide.

[0038] With the described CTAB surface, the silicon dioxide used has an extremely high specific surface area and is classified as Ultra High Surface silicon dioxide.

[0039] The resulting increased reinforcement effect in rubber compounds leads to advantageous abrasion properties.

[0040] Surprisingly, the present invention has succeeded in achieving good abrasion resistance, good processability, and surprisingly improved rolling resistance properties.

[0041] Surprisingly, an improvement was achieved in the conflicting objectives of rolling resistance behavior, abrasion behavior and wet braking behavior, as well as an improvement in the conflicting objectives of the aforementioned properties and processability.

[0042] A suitable silicon dioxide with an average BET surface area of ​​275 m2 / g and an average CTAB surface area of ​​250 m2 / g is available, for example, under the trade name Premium SW from Solvay Silica Korea Co., Ltd.

[0043] Surprisingly, it has also been found that particularly good properties, especially in the conflicting objectives of rolling resistance, abrasion resistance, wet braking, and the processability of the rubber compound, are achieved when the type and quantity of diene rubber, especially NR and BR, as well as silicon dioxide, are specifically selected. Preferably, the rubber compound of these aforementioned embodiments also contains comparatively small amounts of plasticizers, preferably in amounts of 0 to 20 phr, more preferably 0 to 10 phr, and most preferably 1 to 5 phr. The plasticizer(s) contained are preferably selected from the substances listed below.

[0044] The rubber compound according to the invention, including all embodiments, can also contain at least one further filler that has a reinforcing effect or does not have a reinforcing effect.

[0045] Other reinforcing fillers are in particular carbon blacks, preferably selected from industrial carbon blacks and pyrolysis carbon blacks, with industrial carbon blacks being further preferred, and further silicon dioxides which have a CTAB surface area according to ASTM D 3765 of less than 190 m2 / g.

[0046] Carbon blacks known to those skilled in the art for use in rubber compounds can be employed. In one embodiment, the carbon black has an iodine number, according to ASTM D 1510, also referred to as the iodine adsorption number, between 30 and 250 g / kg, preferably 40 to 180 g / kg, particularly preferably 40 to 100 g / kg, and most preferably 60 to 90 g / kg.

[0047] The carbon blacks used preferably have a DBP value according to ASTM D 2414 of 80 to 200 ml / 100 g, preferably 100 to 200 ml / 100 g, and particularly preferably 110 to 180 ml / 100 g. The DBP value according to ASTM D 2414 determines the specific absorption volume of a carbon black or a light-colored filler using dibutyl phthalate. The carbon blacks used also include so-called "recovered" carbon blacks. The carbon blacks used may also be oxidized.

[0048] The total amount of soot contained corresponds to the quantities customary in the industry, preferably 0 to 50 phr.

[0049] The rubber compound may optionally contain coal. This could be, for example, ground bituminous or lignite coal. Preferably, however, HTC coal is used, which is produced by hydrothermal carbonization of at least one starting material. The abbreviation "HTC" stands for hydrothermal carbonization, which is known in the art. In this process, at least one starting material is heated together with water in a closed, pressure- and heat-resistant device, such as, in particular, an autoclave. The starting mixture is thus a suspension and / or solution of the starting material(s) in water. The heating process and the resulting steam generate an increased pressure, which depends in particular on the temperature and the fill level of the device.Hydrothermal carbonization mimics the process that naturally leads to the formation of lignite over millions of years, but does so within a short time, usually just a few hours. "HTC coal" refers to the solid product of hydrothermal carbonization.

[0050] Soot and coal can also be used as a mixture.

[0051] According to advantageous embodiments of the invention, the rubber compound contains at least one further reinforcing filler selected from the group consisting of carbon blacks, preferably selected from industrial carbon blacks and pyrolysis carbon blacks, with industrial carbon blacks being further preferred.

[0052] A carbon black of type N339 is particularly suitable and preferred.

[0053] Preferably, the fillers comprise little or no further silicon dioxides, which have a CTAB surface area according to ASTM D 3765 of less than 200 m² / g or a BET surface area of ​​less than 210 m² / g. "Little" here means an amount of at most 5 phr, preferably at most 1.5 phr.

[0054] 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, and cellulose fibers). Further potentially reinforcing fillers include, for example, carbon nanotubes (CNTs, including discrete CNTs, so-called hollow carbon fibers (HCF), and modified CNTs containing one or more functional groups, such as hydroxy, carboxy, and carbonyl groups), graphite and graphene, and so-called "carbon-silica dual-phase fibers."

[0055] According to the invention, the rubber mixture further contains 1 to 30 pph silanes in the form of at least two organosilicon compounds.

[0056] The unit pph (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.

[0057] Within the scope of the present application, pf refers to all silicon dioxides present, including those contained according to the invention and any other silicon dioxides. This means that other fillers that may be present, such as carbon black, are not included in the calculation of the silane quantity.

[0058] Preferably, the rubber mixture contains as silanes at least a) 1 to 30 ph, preferably 3 to 30 ph, particularly preferably 3 to 20 ph, most preferably 5 to 15 ph, at least one silane A selected from the silanes with the general formulas Al) and A-Xl):

[0059] Al) (R 1 )oSi-R 20 -(SR 30 )m-Sx-(R 30 -S)mR 20 -Si(R 1 )O;

[0060] A-XL) (R 1 )oSi-R 2 -(SR 3 ) q -SX; and optionally b) 0.5 to 30 pphf, preferably 2 to 30 pphf, particularly preferably 3 to 15 pphf, most preferably 3 to 10 pphf, at least one silane B selected from the silanes with the general formulas Bl), B-01 ) and B-02):

[0061] Bl) (R 1 )oSi-R 4 -(SR 5 )uSR 4 -Si(R 1 ) o ; B-01 ) (R 1 )oSi-R 10 -Si(R 1 ) o ;

[0062] B-02) (R 1 )oSi-R 9 ; where the indices o are independently equal to 1, 2 or 3; and where the remainders R 1are the same or different from each other and are selected from Ci-C2o-alkoxy groups, C6-C2o-phenoxy groups, C2-Cio-cyclic dialkoxy groups, C2-C2o-dialkoxy groups, C4-C2o-cycloalkoxy groups, C6-C20-aryl groups, Ci-C2o-alkyl groups, C2-C2o-alkenyl groups, C2-C2o-alkynyl groups, C7-C2o-aralkyl groups, halides or alkyl polyether groups -O-(R 6 -O)rR 7 , where the remainders R 6 are the same or different and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic / aromatic dicovalent Ci-Cso hydrocarbon groups, r is an integer from 1 to 30 and the residues R 7 unsubstituted or substituted, branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl groups, or two R 1correspond to a dialkoxy group with 2 to 10 carbon atoms, where o < 3, or two or more silanes can be linked according to the formulas Al), A-Xl), Bl), B-01 ) and / or B-02) via R groups. 1 or be bridged by condensation, where o per molecule is < 3; and where the condition holds that in formulas Al), A-Xl), Bl), B-01 ) and B-02) in each (R 1 )0Si group at least one R 1 selected from the above-mentioned possibilities, where this R 1 i) is bonded to the silicon atom via an oxygen atom, or ii) is a halide; and wherein the residue R 9 selected from Ce-C2o aryl groups, Ci-C2o alkyl groups, C2-C2o alkenyl groups, C2-C2o alkynyl groups, C1-C2o aralkyl groups; and wherein the R groups 2 , R 3 , R 4 , R 5 , R 10 , R 20 , R 30in each molecule and within a molecule are the same or different, and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic, or mixed aliphatic / aromatic dicovalent Ci-C3O hydrocarbon groups; and where x is an integer from 2 to 10; and where m is 0, 1, 2, or 3; and q is 1, 2, or 3; and u is 1, 2, or 3; and X is a hydrogen atom or a -C(=O)-R 8 group, where R 8 The selected group consists of hydrogen, Ci-C2o alkyl groups, Ce-C2o aryl groups, C2-C2o alkenyl groups and C7-C2o aralkyl groups.

[0063] The silane A contained as component a) according to the invention is, by virtue of the Sx group, where the index x is an integer from 2 to 10, or by virtue of the SX group, a silane that can bind to polymers. In the case of the SX group, this occurs by the elimination of X, i.e., the hydrogen atom or the -C(=O)-R group. 8 Group, possible.

[0064] In the case of the Sx grouping with x equal to 2 to 10, this is made possible by splitting the polysulfide group.

[0065] The mixture may also contain various silanes of type A, i.e., with different Sx and / or SX groups.

[0066] The silane B contained according to the invention has no or only single sulfur atoms that cannot bind to the polymer chains of the diene rubber, since the chemical bond -CSC- does not usually open during vulcanization.

[0067] The silane B contained according to the invention is therefore a so-called “non-binding silane”, whereby in particular the “non-binding to diene rubbers” is meant.

[0068] The mixture may also contain various silanes of type B).

[0069] Preferably, at least 5 pphf to 15 pphf of the silane according to formula A-XII are included as silane A:

[0070] A-X1) (EtO)3Si-(CH2)3-S-(CH2)6-SC(=O)-CH3 Preferably, at least 3 pphf to 10 pphf of the silane according to formula B-Il) are contained as silane B:

[0071] B-Il) (EtO)3Si-(CH2)3-S-(CH2)6-S-(CH2)3-Si(OEt)3

[0072] With such a combination of silanes A and B, preferably the silanes according to formulas A-X1) and B-I1), in combination with the other components contained in the invention, the problem underlying the invention is solved particularly well.

[0073] Preferably, the total amount of silanes A contained, including all embodiments, is 3 to 30 pphf, particularly preferably 3 to 20 pphf, and most preferably 5 to 15 pphf.

[0074] Preferably, the total amount of silanes B contained, including all embodiments, is 2 to 30 pphf, particularly preferably 3 to 15 pphf, and most preferably 3 to 10 pphf.

[0075] Particularly with the preferred, especially preferred, and most preferred amounts and embodiments of silanes A and B, very good properties are obtained with regard to the conflicting objectives of abrasion, rolling resistance, wet braking properties, and the processability of the rubber compound. The molar ratio of silanes A to silanes B is particularly preferably 20:80 to 90:10, more preferably 45:55 to 80:20.

[0076] Furthermore, the rubber compound may contain common additives in usual proportions by weight, which are preferably added during its manufacture in at least one basic mixing stage. These additives include:

[0077] 1) Ozone-protecting waxes and anti-aging agents, such as diamines, like N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl-p-phenylenediamine (DTPD), N-(1,4-dimethylpentyl)-N'-phenyl-p-phenylenediamine (7PPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and / or dihydroquinolines, like 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), and / or substituted bisphenols, like 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (BPH), and / or substituted phenols, like butylhydroxytoluene (BHT),

[0078] 2) Activators, such as zinc oxide and fatty acids (e.g., stearic acid) and / or other activators, such as zinc complexes like zinc ethylhexanoate,

[0079] 3) further activators and / or agents for the binding of fillers, in particular carbon black or silicon dioxide, such as S-(3-aminopropyl)-thiosulfuric acid and / or its metal salts (binding to carbon black) as well as further silane coupling agents (binding to silicon dioxide, in particular silica) in addition to the silanes A and B contained according to the invention,

[0080] 4) Hydrocarbon resins, in particular phenolic resins, especially as adhesive resins,

[0081] 5) Mastication aids, such as 2,2'-dibenzamidodiphenyldisulfide (DBD) and

[0082] 6) Process aids, in particular fatty acid esters and metal soaps, such as zinc soaps and / or calcium soaps,

[0083] 7) Plasticizers, in particular 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 (RTL) or biomass-to-liquid (BTL) oils, preferably with a polycyclic aromatic content of less than 3 wt% according to method IP 346, or triglycerides, such as rapeseed oil, or Faktisse, or hydrocarbon resins, or liquid rubber in the form of liquid polymers, the mean molecular weight of which (determined by GPC = gel permeation chromatography, in accordance with ISO 11344) is between 500 and 20000 g / mol.

[0084] When using mineral oil, it is preferably selected from the group consisting of DAE (Destilled Aromatic Extracts), RAE (Residual Aromatic Extract), TDAE (Treated Destillated Aromatic Extracts), MES (Mild Extracted Solvents) and naphthenic oils.

[0085] The quantity of other additives in the total quantity is preferably 3 to 150 phr, particularly preferably 3 to 100 phr and most preferably 5 to 80 phr.

[0086] The rubber compound according to the invention is preferably used in vulcanized form, particularly in vehicle tires or other vulcanized technical rubber articles.

[0087] The terms “vulcanized” and “crosslinked” are used synonymously within the scope of the present invention.

[0088] The vulcanization of the rubber compound according to the invention is preferably carried out in the presence of sulfur and / or sulfur donors using vulcanization accelerators, wherein some vulcanization accelerators can also act as sulfur donors. The accelerator is selected from the group consisting of thiazole accelerators, mercapto accelerators, sulfenamide accelerators, thiocarbamate accelerators, thiuram accelerators, thiophosphate accelerators, thiohamperm accelerators, xanthate accelerators, and guanidine accelerators. Preferably, at least one sulfenamide accelerator is selected from the group consisting of N-cyclohexyl-2-benzothiazole sulfenamide (CBS), N,N-dicyclohexylbenzothiazole-2-sulfenamide (DCBS), benzothiazole-2-sulfene morpholide (MBS), N-tert-butyl-2-benzothiazole sulfenamide (TBBS), N-tert-butyl-2-benzothiazole sulfenimide (TBSI), and / or at least one guanidine accelerator, such as diphenylguanidine (DPG).In particular, two or more accelerators can also be used.

[0089] Any sulfur-donating substance known to experts can be used as the sulfur-donating substance.

[0090] Furthermore, one or more reversion protectants, such as 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, hexamethylene-1,6-bis(thiosulfate) disodium salt dihydrate, and / or tetrabenzylthiuram disulfide (TBzTD), may be used in the rubber compound.

[0091] Furthermore, vulcanization retarders may be present in the rubber compound.

[0092] The rubber compound is otherwise produced according to the standard procedure in the rubber industry, in which a base mixture containing all components except the vulcanization system (e.g., sulfur and vulcanization-influencing substances) is first produced in one or more mixing stages. The finished mixture is then produced by adding the vulcanization system in the mixing stages, preferably in the final stage.

[0093] The finished compound is further processed, for example, by extrusion or calendering, and formed into the desired shape. The rubber compound according to the invention is particularly suitable for use in vehicle tires, especially pneumatic tires. Its application in all tire components is conceivable in principle, particularly and preferably in the tread and / or the sidewall, most preferably in the tread. In the case of a tread with a cap / base construction, the rubber compound according to the invention is preferably used at least in the cap.

[0094] For use in vehicle tires, the mixture is formed as a ready-to-use compound into the appropriate shape, preferably a sidewall and / or tread, before vulcanization and applied during the manufacture of the vehicle tire blank as is known. The production of the rubber compound according to the invention for use as a body compound in vehicle tires is carried out as already described. The difference lies in the shaping after the extrusion process or the calendering of the compound. The resulting shapes of the still unvulcanized rubber compound for one or more different body compounds then serve to construct a tire blank.

[0095] The term "body compound" refers to the rubber compounds used for the other components of a tire, such as the horn profile, separating plate, inner liner (inner layer), core profile, belt, shoulder, belt profile, carcass, bead reinforcement, bead profile and bandage.

[0096] For the use of the rubber compound according to the invention in belts and straps, in particular in conveyor belts, the extruded, still unvulcanized compound is formed into the appropriate shape and is often provided with reinforcing elements, e.g., synthetic fibers or steel cords, either during or after this process. Further processing is then carried out by vulcanization.

[0097] As already stated at the outset, one object of the present invention is a vulcanizate obtained by sulfur vulcanization of at least one rubber compound according to the invention, including all preferred features. Another object of the present invention, as already stated at the outset, is a vehicle tire comprising at least one component of at least one vulcanizate according to the invention, including all preferred features.

[0098] Within the scope 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-wheeler tires.

[0099] A preferred vehicle tire according to the invention comprises at least one vulcanizate according to the invention, including all preferred features, at least in the tread and / or the sidewall, particularly preferably at least in the tread. A further object of the present invention, as already stated at the outset, is the use of the sulfur-curable rubber compound according to the invention, including all preferred features, for the manufacture of technical rubber articles, such as bellows, conveyor belts, air springs, belts, straps or hoses, as well as shoe soles.

[0100] The invention will now be explained in more detail with reference to comparative and exemplary embodiments, which are summarized in Tables 1 and 3.

[0101] The examples according to the invention are designated E1 and E2, and the comparative examples are designated V1 and V2. Furthermore, examples E10 and E20 according to the invention are disclosed in Table 3.

[0102] Substances used:

[0103] NR: NR TSR 20

[0104] SSBR: Sprintan SLR 3402, Trinseo, glass transition temperature Tg = -62 °C, functionalized, Mw = 470,000 g / mol

[0105] Sprintan SLR 3402 is a solution-polymerized styrene-butadiene copolymer with 15% styrene and 30% vinyl content.

[0106] B1: BR500, Eneos (JSR), Tg = -88 °C, functionalized, Mw = 512,000 g / mol. BR500 is a butadiene rubber (BR) with a low cis content. BR500 has a trans content of 49%, a cis content of 35%, and a vinyl content of 15%. BR500 is functionalized and exhibits a high carbon black (soot) affinity.

[0107] BR 2: BR511, Eneos (JSR), Tg = -78 °C, functionalized, Mw = 361,000 g / mol. BR511 is a low-cis butadiene rubber (BR). BR511 has a trans content of 37%, a cis content of 30%, and a vinyl content of 30%. BR511 is functionalized and exhibits a high affinity for silicon dioxide.

[0108] BR 3: KBR820, manufactured by KKPC (Kumho), Tg = -92 °C, functionalized. KBR820 is a low-cis butadiene rubber (BR). It has a cis content of 40.5% and a vinyl content of 12%. KBR820 is functionalized and exhibits a high affinity for silicon dioxide.

[0109] Soot:

[0110] - in V1: BC2123, Birla Carbon,

[0111] - otherwise: BC2123 or N220, Birla Carbon; or N339, Orion Engineered Carbons.

[0112] Silica 1: Zeosil® 1165MP, Solvay, mean CTAB surface area 157 m2 / g, mean BET surface area 161 m2 / g,

[0113] Silica 2: Premium SW, Solvay, average CTAB surface area 250 m² / g, average BET surface area 275 m² / g,

[0114] Silane 1: Mixture of organosilicon compounds with at least two components having the following structure according to formulas A-XII): (EtO)3Si-(CH2)3-S-(CH2)6-S-C(=O)-CH3 and B-Il): (EtO)3Si-(CH2)3-S-(CH2)6-S-(CH2)3-Si(OEt)3

[0115] Silane 2: Bis-[3-(triethoxysilyl)-propyl] disulfide (TESPD, silane with 75% S2), Evonik Industries

[0116] Silane 3: 3-Octanoylthio-1-propyltriethoxysilane, NXT, Momentive

[0117] 1) Other additives: zinc oxide, zinc soap, stearic acid, plasticizers, antioxidants, ozone-protecting wax, liquid polybutadiene

[0118] 2) DPG and vulcanizing chemicals (volcanic chemicals): Sulfenamide accelerator and sulfur

[0119] The silane (according to formula A-X1) was produced as follows:

[0120] Na2CO3 (59.78 g; 0.564 mol) and an aqueous solution of NaSH (40% in water;

[0121] 79.04 g (0.564 mol) were pre-treated with water (97.52 g). Then tetrabutylphosphonium bromide (TBPB) (50% in water; 3.190 g; 0.005 mol) was added, followed by acetyl chloride (40.58 g; 0.517 mol) dropwise over 1 h, maintaining a reaction temperature of 25–32 °C. After complete addition of the acetyl chloride, the mixture was stirred for 1 h at room temperature. Then TBPB (50% in water; 3.190 g; 0.005 mol) and 1-chloro-6-thiopropyltriethoxysilylhexane (see above;

[0122] 167.8 g (0.470 mol) was added and heated under reflux for 3–5 h. The reaction progress was monitored by gas chromatography. When the 1-chloro-6-thiopropyltriethoxy-silylhexane had reacted to >96%, water was added until all salts had dissolved and the phases were separated. The volatile components of the organic phase were removed under reduced pressure, and S-(6-((3-(Triethoxysilyl)propyl)thio)hexyl)thioacetate) was obtained as a yellow to brown liquid (yield: 90%, molar ratio: 97% S-(6-((3-(Triethoxysilyl)propyl)thio)hexyl)thioacetate (Silane A-XII), 3% bis(thiopropyltriethoxysilyl)hexane (Silane B-Il); wt%: 96 wt% S-(6-((3- (Triethoxysilyl)propyl)thio)hexyl)thioacetate (Silane A-XII), 4 wt% 1,6-bis(thiopropyltriethoxysilyl)hexane (Silane B-Il)).

[0123] The silane of formula B-Il): 1,6-Bis(thiopropyltriethoxysilyl)hexane) was prepared as follows:

[0124] Sodium ethoxide (21% in EtOH; 82.3 g; 0.254 mol; 2.05 eq) is added to mercaptopropyltriethoxysilane (62.0 g; 0.260 mol; 2.10 eq) in such a way that the reaction temperature does not exceed 35 °C. After complete addition, the mixture is heated under reflux for 2 h. The reaction mixture is then added to 1,6-dichlorohexane (19.2 g; 0.124 mol; 1.00 eq) over 1.5 h at 80 °C. After complete addition, the mixture is heated under reflux for 3 h and then allowed to cool to room temperature. Precipitated salts are filtered off, and the product is evaporated from the solvent under reduced pressure. The product (yield: 88%, purity: > 99% on 13C NMR) was obtained as a clear liquid.

[0125] NMR method: The molar ratios and mass fractions given as analytical results in the examples above are derived from 13 C-NMR measurements with the following parameters: 100.6 MHz, 1000 scans, solvent CDCb, internal standard for calibration: tetramethylsilane, relaxation aid Cr(acac)s, for the determination of the mass fraction in the product a defined amount of dimethyl sulfone was added as an internal standard and the mass fraction was calculated from the molar ratios of the products.

[0126] The mass fractions are given in Table 1. Table 1:

[0127] The mixture was produced according to the procedure common in the rubber industry under normal conditions in 2-5 stages.

[0128] Test specimens were produced from all mixtures by vulcanization to t95 to t100 (measured on the Moving Die Rheometer according to ASTM D 5289-12 / ISO 6502) under pressure at 140-150 °C and material properties typical for the rubber industry were determined with these test specimens using the test procedures specified below.

[0129] • Shore A hardness at room temperature (RT) and at 70 °C according to ISO 868, • Rebound elasticity at room temperature (RT) and at 70 °C according to ISO 4662,

[0130] • Stress value at 300% elongation (M 300) at RT and 70 °C, tensile strength and elongation at break at room temperature (RT), according to DIN 53 504.

[0131] Furthermore, tire tests were carried out, specifically in the comparative examples V1 and V2, as well as in the inventive examples E1 and E2, each with the mixture as a tread cap. The following test methods were applied:

[0132] • Wet braking: ABS braking from 80 km / h, wet concrete, low p (low p),

[0133] • Rolling resistance: according to ISO 28580

[0134] • Abrasion: Relative weight loss of the respective tires after 15,000 km to 20,000 km of road driving at an average temperature of 5 to 10 °C.

[0135] The measured values ​​are given as a percentage relative to the measured values ​​of the comparison example V1. A higher percentage indicates better tire performance.

[0136] Table 2

[0137] As can be seen in Table 2, the rubber compounds according to the invention, in particular compound E1, surprisingly achieve a significantly improved wet braking performance in tires according to the invention, while maintaining at least the same or improved rolling resistance and abrasion behavior compared to V1. Compared to V2, the rolling resistance and abrasion behavior can be significantly improved, and the wet braking performance can be improved even further.

[0138] The tire according to E2 exhibits particularly advantageous abrasion and rolling resistance characteristics.

[0139] Furthermore, the rubber compounds according to the invention exhibit optimal processability, in particular mixability and extrudability. Thus, the conflict of objectives arising from the aforementioned properties is resolved at a higher level by the rubber compound according to the invention.

[0140] Furthermore, modified examples of rubber compounds E10 and E20 according to the invention were tested. E10 and E20 correspond to E1 and E2 (see Table 1) except that the proportion of BR was increased from 20 phr to 40 phr and the proportion of NR was decreased from 80 phr to 60 phr.

[0141] For E10 and E20, the measurement results described in Table 3 are obtained analogously to the measurements in Table 2. This shows that the problem according to the invention is also solved by a mixture according to examples E10 or E20.

[0142] Table 3

Claims

Patent claims 1. Sulfur-curable rubber compound comprising at least the following components: a) 50 to 100 phr of at least one polyisoprene, preferably one natural polyisoprene, b) 0 to 50 phr of at least one butadiene rubber, wherein the butadiene rubber is functionalized for the attachment of silica and preferably has a glass transition temperature Tg between -70 °C and -110 °C, c) 20 to 100 phr, preferably 30 to 70 phr of at least one high-surface-area silicon dioxide with a BET surface area according to DIN ISO 9277 of at least 210 m² / g, preferably 265 to 320 m² / g, d) 1 to 30 phr of silanes selected from at least two organosilicon compounds.

2. Sulfur-curable rubber compound according to claim 1, wherein the proportions of natural polyisoprene and butadiene rubber add up to exactly 100 phr, preferably to 100.00 phr.

3. Sulfur-curable rubber compound according to one of claims 1 or 2, wherein the butadiene rubber contained in the rubber compound according to the invention is of the low-cis type, i.e. the cis content in the butadiene rubber is less than 90 wt.%.

4. Sulfur-curable rubber compound according to one of claims 1 to 3, wherein the two organosilicon compounds at least 1 to 30 pphf, preferably 5 to 15 pphf of a silane A selected from the silanes with the general formulas Al) and A-Xl): Al) (R 1 )oSi-R 20 -(SR 30 )m-Sx-(R 30 -S)mR 20 -Si(R 1 )O; A-XL) (R 1 )oSi-R 2 -(SR 3 ) q -SX; and 0.5 to 30 pphf, preferably 3 to 10 pphf of a silane B, which is selected from the silanes with the general molecular formulas Bl), B-01 ) and B-02): Bl) (R 1 )oSi-R 4 -(SR 5)uSR 4 -Si(R 1 ) o ; B-01 ) (R 1 )oSi-R 10 -Si(R 1 ) o ; B-02) (R 1 )oSi-R 9 ; comprising, where the indices o are independently equal to 1, 2 or 3; and where the remainders R 1 are the same or different from each other and are selected from Ci-C2o-alkoxy groups, C6-C2o-phenoxy groups, C2-Cio-cyclic dialkoxy groups, C2-C2o-dialkoxy groups, C4-C20-cycloalkoxy groups, Ce-C2o-aryl groups, C1-C20-alkyl groups, C2-C2o-alkenyl groups, C2-C2o-alkynyl groups, C7-C2o-aralkyl groups, halides or alkyl polyether groups -O-(R 6 -O)rR 7 , where the remainders R 6 are the same or different and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic / aromatic dicovalent Ci-Cao hydrocarbon groups, r is an integer from 1 to 30 and the residues R 7unsubstituted or substituted, branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl groups, or two R 1 correspond to a dialkoxy group with 2 to 10 carbon atoms, where o < 3, or two or more silanes can be linked according to the formulas Al), A-Xl), Bl), B-01 ) and / or B-02) via R groups. 1 or be bridged by condensation, where o per molecule is < 3; and where the condition holds that in formulas Al), A-Xl), Bl), B-01 ) and B-02) in each (R 1 )0Si group at least one R 1 selected from the above-mentioned possibilities, where this R 1 is bonded to the silicon atom via an oxygen atom or is a halide; and wherein the residue R 9 selected from C6-C20 aryl groups, C1-C20 alkyl groups, C2-C20 alkenyl groups, C2-C20 alkynyl groups, C7-C20 aralkyl groups; and wherein the R groups 2 , R 3 , R 4 , R 5, R 10 , R 20 , R 30 in each molecule and within a molecule are the same or different, and are branched or unbranched, saturated or unsaturated, aliphatic, aromatic, or mixed aliphatic / aromatic dicovalent Ci-Cso hydrocarbon groups; and where x is an integer from 2 to 10; and where m is equal to 0, 1, 2, or 3; and q is equal to 1, 2, or 3; and u is equal to 1, 2, or 3; and X is a hydrogen atom or a -C(=O)-R 8 group, where R 8 The selected group consists of hydrogen, Ci-C2o alkyl groups, Ce-C2o aryl groups, C2-C2o alkenyl groups and C7-C2o aralkyl groups.

5. Sulfur-curable rubber compound according to claim 4, wherein silane A comprises 5 pphf to 15 pphf of the silane according to formula A-X1): A-Xll) (EtO)3Si-(CH2)3-S-(CH2)6-SC(=O)-CH3.

6. Sulfur-curable rubber compound according to claim 4 or 5, wherein silane B 3 pphf to 10 pphf of the silane according to formula B-Il) are contained: B-Il) (EtO)3Si-(CH2)3-S-(CH2)6-S-(CH2)3-Si(OEt)3.

7. Sulfur-curable rubber compound according to any one of claims 4 to 6, wherein the molar ratio of silane A to silane B is 20:80 to 90:10, preferably 45:55 to 80:

20.

8. Sulfur-curable rubber compound according to any one of claims 1 to 7, wherein the at least one high-surface silicon dioxide has a CTAB surface area according to ASTM D 3765 of over 200 m2 / g, preferably 245 to 300 m2 / g.

9. Sulfur-curable rubber compound according to any one of claims 1 to 8, wherein the rubber compound according to the invention does not contain any liquid rubbers.

10. Vulcanizate obtained by sulfur vulcanization of at least one rubber mixture according to any one of claims 1 to 9.

11. Vehicle tire, characterized in that it comprises at least one vulcanizate according to claim 10 in at least one component.

12. Vehicle tire according to claim 11, characterized in that it comprises at least one vulcanizate according to claim 10 at least in the tread and / or the sidewall, particularly preferably at least in the tread.

13. Use of the rubber compound according to any one of claims 1 to 9 for the manufacture of technical rubber articles, such as bellows, conveyor belts, air springs, belts, straps or hoses, as well as shoe soles.

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