Rubber mixture and tire

Abstract

The invention relates to a sulfur-crosslinkable rubber mixture, in particular for the tread of pneumatic vehicle tyres, containing at least the following components: at least one diene rubber, 5 to 70 phr (based on 100 parts by weight of all rubbers in the mixture) of at least one terpene resin based on biorenewable raw materials to a degree of greater than 95%, -1 to 40 phr of at least one liquid polybutadiene, which is silicone modified and has an average molecular weight Mw through GPC of 500 to 18000 g / mol, and-40 to 350 phr of at least one filler.

Description

TECHNICAL FIELD

[0001] The present invention relates to a sulfur-crosslinkable rubber mixture, in particular for the tread of a pneumatic vehicle tire.

[0002] The present invention further relates to a pneumatic vehicle tire having at least one component made from such a sulfur-vulcanized rubber mixture. BACKGROUND

[0003] Since the running properties of a tire, in particular of a pneumatic vehicle tire, depend to a large extent on the rubber composition of the tread, there are particularly high requirements on the composition of the tread mixture. There is a trade-off between most known tire properties, such as wet grip characteristics, braking characteristics, handling characteristics, rolling resistance, winter properties, wear characteristics and tear properties. Various attempts have been made to positively influence the properties of a tire by changing the polymer components, fillers and other admixtures in the tread mixture.

[0004] In addition to the above-mentioned objectives with regard to the properties of the mixture and the vulcanized rubber, there is now an effort to use rubber mixtures for vehicle tires that employ as sustainable and environmentally friendly materials as possible in order to reduce the dependency on fossil raw materials and to minimize the emission of greenhouse gases. One way to achieve a sustainable product is by recycling no longer needed old products, for example recycling old tires, wherein the recycled material is recycled into the production of new tires. Another way to increase the sustainability of a product is to use substances from renewable raw materials as additives for the rubber mixture. Such additives from renewable raw materials include vegetable oils, resins based on renewable raw materials or rice husk silica. The latter is a silica produced from biobased sodium silicate from rice husk ash.

[0005] EP 3 350 259 B1 and EP 3 350 260 B1 disclose rubber compounds for tire treads, which have good property profiles and contain terpene-styrene resins and non-functionalized liquid polybutadienes.

[0006] US 10,654,995 B2 describes a rubber mixture for tire treads, which contains an a-pinene-based resin and a liquid polybutadiene functionalized with hydroxyl end groups. SUMMARY

[0007] The problem addressed by the present invention is to provide sustainable rubber mixtures for the tread of a pneumatic vehicle tire, which produce good rolling resistance as well as good structural durability in the tire.

[0008] This object is achieved according to the present application by a sulfur-crosslinkable rubber mixture, in particular for a tread of a pneumatic vehicle tire, comprising at least the following ingredients:

[0009] at least one diene rubber,

[0010] 5 to 70 phr (parts by weight per 100 parts by weight of all rubbers in the mixture) of at least one terpene resin based to more than 95% on biorenewable raw materials,

[0011] 1 to 40 phr of at least one liquid polybutadiene, which is silicone-modified and has an average molecular weight M w by GPC of 500 to 18 000 g / mol,

[0012] 40 to 350 phr of at least one filler.

[0013] It has now surprisingly been found that at least one terpene resin based to more than 95% on biorenewable raw materials in combination with a liquid polybutadiene, which is silicone-modified and has an average molecular weight M w by GPC of 500 to 18 000 g / mol, in a diene rubber mixture containing silica in the specified amounts of this particular combination results in a low maximum loss factor tan delta max at 55°C and a low tan delta (10%) by RPA, which correlates with a low rolling resistance when used in a tire tread. The mixture according to the present application shows at the same time good stress-strain properties, like a high tensile strength and a high elongation at break, which are associated with an improved structural durability. Thus, the use of the rubber mixture according to the present application in a tread of a pneumatic vehicle tire results in a pneumatic vehicle tire characterized by a good sustainability as well as a good rolling resistance and a good durability.

[0014] The unit "phr" (parts per hundred parts of rubber by weight) used in this document is the standard unit for amounts of mixture formulations in the rubber industry. The amounts in parts by weight of the individual substances are always based here on the total mass of 100 parts by weight of all solid rubbers present in the mixture.

[0015] The term "terpene resin based on more than 95% biorenewable raw materials" is to be understood in the context of the present application to mean a terpene resin which is physically produced from renewable raw materials as a source, wherein a plant origin is particularly preferred.

[0016] According to the present application, the rubber mixture comprises at least one diene rubber. Diene rubbers are rubbers formed by polymerization or copolymerization of dienes and / or cyclic olefins and thus have C=C double bonds in the main chain or side groups.

[0017] The diene rubber is preferably selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), epoxidized polyisoprene (ENR), butadiene rubber (BR), 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, liquid rubber having a molecular weight M w of greater than 20 000 g / mol, halogenated butyl rubber, polynorbornene, isoprene-isobutylene copolymer, ethylene-propylene-diene rubber, nitrile rubber, chloroprene rubber, acrylate rubber, fluoro rubber, silicone rubber, polysulfide rubber, epichlorohydrin rubber, styrene-isoprene-butadiene terpolymer, hydrogenated acrylonitrile butadiene rubber, and hydrogenated styrene-butadiene rubber.

[0018] Nitrile rubber, hydrogenated acrylonitrile-butadiene rubber, chloroprene rubber, butyl rubber, halogenated butyl rubber or ethylene-propylene-diene rubber are in particular used in the production of industrial rubber articles such as belts, conveyor belts and hoses, and / or shoe soles. Preferably mix compositions for these rubbers known to the person skilled in the art specific in respect of fillers, plasticizers, vulcanization systems and additives are used here.

[0019] In a particularly preferred embodiment of the application, the diene rubber is selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), solution-polymerized styrene-butadiene rubber (SSBR) and emulsion-polymerized styrene-butadiene rubber (ESBR). This rubber mixture is particularly suitable for use in the tread of a vehicle tire. Natural polyisoprene is understood to mean rubber that can be obtained by harvesting from sources such as rubber trees (Hevea brasiliensis) or non-rubber tree sources (for example guayule or dandelion (for example Taraxacum koksaghyz)). Natural polyisoprene (NR) is understood to mean non-synthetic polyisoprene.

[0020] The rubber mixture according to the application contains 5 to 70 phr, preferably 20 to 60 phr, particularly preferably 30 to 50 phr, of at least one terpene resin which is based to a greater than 95% extent on biologically renewable raw materials. It is also possible to use two or more different terpene resins in the mixture. It is preferred when the terpene resin is based to a 100% extent on biologically renewable raw materials.

[0021] Terpene resins based on biorenewable raw materials to an extent of more than 95% are obtainable, for example, from raw materials produced in the production of fragrances from orange peel. However, terpene resins based on by-products from softwood pulp production are preferred. Such by-products are commercially available in large quantities and can be upgraded to terpene resins on an industrial scale.

[0022] In a preferred development of the invention, the terpene resin is not based on limonene.

[0023] The terpene resins are preferably based on α- and β-pinene.Such terpene resins can be produced from by-products of softwood pulp production.

[0024] The terpene resins based to an extent of more than 95% on biorenewable raw materials preferably have an average molecular weight M of 800 to 1500 g / mol by GPC. w Such terpene resins are easy to process and result in good tear properties.

[0025] In a preferred development of the invention, the terpene resin has a softening point of 100 to 140°C, preferably 110 to 130°C.

[0026] In order to achieve good braking characteristics of a tire whose tread consists of the rubber mixture according to the invention, the terpene resin has a glass transition temperature Tg according to DSC of 50 to 100° C., preferably 50 to 80° C.

[0027] Terpene resins that can be used according to the present invention may include, for example, the types available from Kraton Chemicals SAS. 8115 and Those of 8125. These are based to a 100% extent on biorenewable raw materials instead of limonene.

[0028] The rubber mixture according to the invention contains 1 to 40 phr, preferably 2 to 17 phr, of at least one liquid polybutadiene which is silicone-modified and has an average molecular weight M of 500 to 18 000 g / mol as determined by GPC. w . Abbreviation M w Represents the weight average molecular weight of the polymer. w Determined by gel permeation chromatography (GPC with polybutadiene standards). M 500 to 18 000 g / mol w The value range means that polybutadiene is liquid at room temperature. Therefore, for the sake of brevity, in the context of the present invention, the short expression "liquid polybutadiene" is also used. w Values ​​are based on inclusion of silicone-modified polybutadiene.

[0029] The liquid polybutadiene can be silicone-modified at the end and / or along the chain.

[0030] It is preferred when the liquid polybutadiene has been modified with at least one group of the formula I):

[0031] (R 1 R 2 R 3 )Si-I)

[0032] wherein R 1 , R 2 , R 3 can be identical or different and can be selected from linear or branched alkoxy, cycloalkoxy, alkyl, cycloalkyl or aryl groups having 1 to 20 carbon atoms, and wherein the group of the formula I) is attached to the polymer chain of the polybutadiene directly or via a bridge, and wherein the bridge consists of a saturated or unsaturated carbon chain which can also contain cyclic and / or aliphatic and / or aromatic elements and heteroatoms in or on the chain. This modification leads to the advantage of tire rolling resistance.

[0033] In a preferred development of the present application, the liquid polybutadiene is modified at the end with triethoxysilane groups. These polybutadienes are easy to manufacture and are commercially available on an industrial scale, for example from Evonik under the name EP ST-E 60.

[0034] For improving the winter properties and the rolling resistance, the silicone-modified liquid polybutadiene has a glass transition temperature T g of the polymer (T g ) is determined by dynamic scanning calorimetry (DSC, according to DIN 53765:1994-03 or ISO 11357-2:1999-03, calibrating the DSC with a low-temperature device, calibrating according to the device type and manufacturer's instructions, the sample in an aluminum crucible with aluminum lid, cooling at 10 °C / min to a temperature below -120 °C).

[0035] The liquid polybutadiene preferably has a vinyl content (content of 1,2-bonded butadiene of the monomers of the polymer chain of the polybutadiene) of 5% to 30%, particularly preferably 10% to 25%. The liquid polybutadiene preferably has a 1,4-trans content (based on the monomers of the polymer chain of the polybutadiene) of 40% to 75%. The cis content of the liquid polybutadiene is preferably 5% to 30% (based on the monomers of the polymer chain of the polybutadiene).

[0036] The rubber mixture contains 40 to 350 phr of at least one filler. This can comprise customary amounts of fillers such as carbon black, silica, aluminosilicates, chalk, starch, magnesium oxide, titanium dioxide or rubber gels, wherein the fillers can be used in combination. Carbon nanotubes (CNTs, including discrete CNTs, so-called hollow carbon fibers (HCFs), and modified CNTs containing one or more functional groups such as hydroxyl, carboxyl and carbonyl groups) are also conceivable. Graphite and graphene and so-called "carbon-silica two-phase fillers" can be used as fillers.

[0037] Different fillers can also be used in the mixture.

[0038] If carbon black is present in the rubber mixture, any of the types of carbon black known to the person skilled in the art can be used. However, it is preferred to use carbon black having an iodine adsorption value according to ASTM D 1510 of 30 to 180 g / kg, preferably 30 to 130 kg / g, and a DBP value according to ASTM D 2414 of 80 to 200 ml / 100 g, preferably 100 to 200 ml / 100 g, more preferably 100 to 180 ml / 100 g. For applications in vehicle tires, this achieves particularly good rolling resistance indices (rebound resilience at 70°C) as well as good remaining tire properties.

[0039] In order to reduce the rolling resistance, it has been found to be advantageous when the rubber mixture contains 20 to 200 phr of silica as filler. Further fillers, such as carbon black, are additionally present in the mixture, as a result of which a total of 40 to 350 phr of filler is present in the mixture.

[0040] A variety of different silicas can be used, such as "low surface area" or highly dispersible silicas, including those in mixtures. It is preferred to use finely divided, precipitated silicas having a CTAB surface area (according to ASTM D 3765) of 30 to 350 m 2 / g, preferably 110 to 250 m 2 / g. Silicas that can be used include conventional silicas, such as those of the VN3 type (trade name Hi-Sil®) from Wacker, or are highly dispersible silicas known as HD silicas (for example Ultrasil 7000 from Wacker). Silicas produced from rice husk ash are also suitable.

[0041] In order to improve the processability and in order to bond the silica to the diene rubber in the silica-containing mixture, it is preferred to use at least one silane coupling agent in the rubber mixture in an amount of 1-15 phf (parts by weight, based on 100 parts by weight of silica). The silane coupling agent can also be used as a mixture.

[0042] The expression phf (parts per hundred parts of filler by weight) used in this document is a unit of measure commonly used in the rubber industry for the amount of coupling agent for polar fillers. In the context of this application, phf relates to the silica present, meaning that any other fillers present (such as carbon black) are not included in the calculation of the amount of silane coupling agent.

[0043] In the context of the pretreatment (pre-modification) carried out during the mixing (in situ) of the rubber / rubber mixture or before the filler is added to the rubber, the silane coupling agent reacts with the surface silanol groups or other polar groups of the silicon dioxide. The silane coupling agents that can be used here include all silane coupling agents for rubber mixtures known to those skilled in the art. Such coupling agents known by the prior art are difunctional organosilanes that have at least one alkoxy, cycloalkoxy or phenoxy group as a leaving group on the silicon atom and have a group as another functional group that can optionally undergo a chemical reaction with the double bond of the polymer after splitting. The latter group can, for example, include the following chemical groups: -SCN, -SH, -NH2 or -S x - (where x = 2-8). Thus, silane coupling agents that can be used include, for example, 3-mercaptopropyltriethoxysilane, 3-thiocyanatopropyltrimethoxysilane, or 3,3'-bis(triethoxysilylpropyl)polysulfides having 2 to 8 sulfur atoms, such as 3,3'-bis(triethoxysilylpropyl)tetrasulfide (TESPT), the corresponding disulfides, or mixtures of other sulfides having 1 to 8 sulfur atoms with various sulfides in varying amounts. TESPT can also be added, for example, as a mixture with industrial carbon black (trade name X50S from Degussa). Blocked mercaptosilanes, such as those known from WO 99 / 09036, can also be used as silane coupling agents. It is also possible to use silanes as described in WO 2008 / 083241 A1, WO 2008 / 083242 A1, WO 2008 / 083243 A1 and WO 2008 / 083244 A1. It is also possible to use silanes as described in WO 2008 / 083241 A1, WO 2008 / 083242 A1, WO 2008 / 083243 A1 and WO 2008 / 083244 A1. Silanes sold under the name Silane® or those sold by Evonik Industries under the name VP Si 363. It is also possible to use “silated core polysulfides” (SCP, polysulfides with a silylated core), which are described, for example, in US 20080161477 A1 and EP 2 114 961 B1.

[0044] It is preferred when the at least one silane coupling agent in the rubber mixture is 3,3'-bis(triethoxysilylpropyl)disulfide (TESPD).

[0045] The rubber mixture according to the application can also contain different plasticizers. These are preferably present in the mixture in an amount of 5 to 50 phr, particularly preferably 5 to 30 phr. These plasticizers do not include organosilicon-modified liquid polybutadienes.

[0046] The plasticizers are preferably selected from the group consisting of plasticizers from renewable raw materials such as rapeseed oil or sunflower oil, mineral oils, phosphoric esters such as tris-(2-ethylhexyl)phosphate and liquid polymers with a weight average molecular weight distribution Mw w of 60 000 g / mol or less by GPC.

[0047] When a mineral oil is used, the mineral oil is preferably selected from the group consisting of DAE (distilled aromatic extract), RAE (residual aromatic extract), TDAE (treated distilled aromatic extract), MES (mildly extracted solvent), white mineral oil and naphthenic oil, with RAE being particularly preferred.

[0048] In an advantageous development of the application, the plasticizer used is a vegetable oil. This is an advantage from the environmental and economic point of view and provides advantageous properties in the tire. It is particularly preferred when the vegetable oil is rapeseed oil.

[0049] The rubber mixture can further contain customary additives in customary parts by weight, which are preferably added during production of the mixture in at least one primary mixing stage.

[0050] These additives include

[0051] a) aging 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) and 2,2,4- trimethyl-1,2-dihydroquinoline (TMQ),

[0052] b) activators, such as zinc oxide and fatty acids (e.g. stearic acid) or zinc complexes, such as zinc ethylhexanoate,

[0053] c) waxes,

[0054] d) plastication aids, such as 2,2'-dibenzamidodiphenyl disulfide (DBD), and

[0055] e) Processing aids, such as fatty acid salts, for example zinc soaps, and fatty acid esters and derivatives thereof.

[0056] The proportion of the total amount of further additives is 3 to 150 phr, preferably 3 to 100 phr, and more preferably 5 to 80 phr.

[0057] The vulcanization of the rubber mixture is carried out in the presence of sulfur and / or a sulfur donor with the aid of a vulcanization accelerator, some of which can also serve as a sulfur donor. The accelerator is selected from the group consisting of a thiazole accelerator and / or a mercapto accelerator and / or a sulfenamide accelerator and / or a thiocarbamate accelerator and / or a thiuram accelerator and / or a thiophosphate accelerator and / or a thiourea accelerator and / or a xanthate accelerator and / or a guanidine accelerator.

[0058] It is preferred to use a sulfenamide accelerator selected from the group consisting of N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) and / or N,N-dicyclohexylbenzothiazolyl-2-sulfenamide (DCBS) and / or benzothiazolyl-2-sulfenylmorpholine (MBS) and / or N-tert-butyl-2-benzothiazolylsulfenamide (TBBS).

[0059] The rubber mixture may also contain vulcanization retardants.

[0060] The sulfur-donating substance used can be selected from any of the sulfur-donating substances known to those skilled in the art. When the rubber mixture contains a sulfur-donating substance, it is preferably selected from the group consisting of, for example, thiuram disulfides, such as tetrabenzylthiuram disulfide (TBzTD), tetramethylthiuram disulfide (TMTD) or tetraethylthiuram disulfide (TETD), thiuram tetrasulfides, such as dipentamethylenethiuram tetrasulfide (DPTT), dithiophosphates, such as DipDis (bis(diisopropyl)thiophosphoryl disulfide), bis(O,O-2-ethylhexylthiophosphoryl)polysulfide (e.g., Rhenocure SDT) Rheinchemie GmbH), zinc dichlorodithiophosphate (e.g. Rhein Chemie) or zinc alkyl dithiophosphates, and 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane and diaryl and dialkyl polysulfides.

[0061] For example, under the trade name or Other available network-forming systems or those described in WO 2010 / 049216 A2 can also be used in the rubber mixture. The latter system contains a vulcanizing agent that crosslinks with a functionality greater than four and at least one vulcanization accelerator.

[0062] During the production of the rubber mixture, it is preferred that at least one vulcanizing agent selected from the group consisting of sulfur, a sulfur donor, a vulcanization accelerator and a vulcanizing agent crosslinking with a functionality greater than four is added to the rubber mixture in the final mixing stage. This makes it possible to produce a sulfur-crosslinked rubber mixture for use in rubber products, especially in pneumatic vehicle tires, from the mixed final mixture by vulcanization.

[0063] The terms "vulcanized" and "crosslinked" are used synonymously in the context of the present invention.

[0064] The rubber mixture is produced using methods customary in the rubber industry, in which a preliminary mixture containing all ingredients except the vulcanization system (sulfur and substances influencing vulcanization) is first produced in one or more mixing stages. The final mixture is produced by adding the vulcanization system in the final mixing stage. This final mixture is further processed, for example by an extrusion operation, and brought into the appropriate shape. This is followed by further processing by vulcanization, in which sulfur crosslinking takes place due to the addition of the vulcanization system in the context of the present invention.

[0065] The rubber mixture can be used in a variety of different rubber products. It can be used in different components of a pneumatic vehicle tire. It is preferably used to produce a pneumatic vehicle tire, such as a passenger car, truck, truck or two-wheeled vehicle tire, in which the rubber mixture forms at least the road-contacting portion of the tread.

[0066] In a pneumatic vehicle tire, the tread can consist of a single mixture designed according to the invention. However, it is commonplace for today's pneumatic vehicle tires to have a tread referred to as a crown / base construction. Here "crown" means the portion of the tread that is in contact with the road, arranged radially on the outside (upper tread portion or tread crown). Here "base" means the portion of the tread that is arranged radially on the inside and thus does not come into contact with the road during driving operation, or only at the end of the tire's life (lower tread portion or tread base). In the case of a pneumatic vehicle tire having such a crown / base structure, the rubber mixture used at least for the crown is designed according to claim 1.

[0067] The pneumatic vehicle tire of the present invention can also have a tread consisting of various tread mixtures arranged in rows next to each other and / or above and below each other (multicomponent tread).

[0068] In the production of a pneumatic vehicle tire, the mixture is brought into the shape of the tread, preferably at least the shape of the tread crown, as a final mixture before vulcanization and applied in a known manner in the production of a vehicle tire blank. The tread, preferably at least the tread crown, can also be wound onto the tire blank in the form of a narrow strip of rubber mixture.

[0069] The invention encompasses all advantageous configurations reflected, inter alia, in the claims. The invention particularly also encompasses configurations resulting from the combination of different features (e.g. ingredients of the rubber mixture) with different preferred levels, such that the invention also encompasses the combination of a first feature described as "preferred" or in the case of an advantageous embodiment with a further feature described as "particularly preferred". DETAILED DESCRIPTION

[0070] The invention will now be elucidated in detail with reference to comparative and working examples summarized in Table 1.

[0071] The comparative mixtures are here designated V, the mixtures of the invention are designated E.

[0072] The mixtures are produced in three stages in a laboratory mixer under standard conditions by methods customary in the rubber industry, in which in the first mixing stage (premixing stage) all the ingredients except the vulcanization system (sulfur and substances influencing vulcanization) are mixed first. In the second mixing stage, the premix is mixed again. In the third stage (final mixing stage) the vulcanization system is added to give the final mixture, which is mixed at 90 to 120°C.

[0073] The loss factor tan delta (10%) of the mixtures is then determined using an RPA (Rubber Processing Analyzer) according to ASTM D6601 by a second strain sweep in the conditioned state of vulcanization at 1 Hz, 70°C and 10% strain, wherein the test sample is produced in the device by 10 minutes vulcanization under pressure at 170°C.

[0074] Furthermore, test samples are produced using all the mixtures by vulcanization under pressure at 160°C for 20 minutes, and these test samples are used to determine typical material properties for the rubber industry by the test methods specified below:

[0075] - Shore A hardness at room temperature according to ISO 868

[0076] - Resilience at room temperature and at 70°C according to ISO 4662

[0077] - Tensile strength at room temperature according to ISO 37

[0078] - Elongation at break at room temperature according to ISO 37

[0079] - Maximum loss factor tan delta at 55°C according to ISO 4664-1 as maximum value of strain sweep (frequency 10 Hz) from dynamic-mechanical measurement max

[0080] Maximum loss factor tan d at 55 °C max A low loss factor tan d at 55 °C max and a low loss factor tan d by RPA (10%) indicate a low rolling resistance. Stress-strain properties like tensile strength and elongation at break can be related to structural durability.

[0081] Table 1

[0082]

[0083] SLR-3402, Trinseo, functionalized solution polymerized styrene-butadiene copolymer with functionalization for polymer / silica and polymer / carbon black interactions, T g = -62 °C

[0084] b LBR-302, Kuraray, liquid polybutadiene, T g = -85 °C

[0085] EP ST-E 60, Evonik, liquid polybutadiene end-modified with triethoxysilane, Tg = -80 °C, average molar mass M w ca. 13 600 g / mol (GPC, polybutadiene standards)

[0086] d 1165 MP, Solvay S.A., BET surface area = 155 m 2 / g (measured with nitrogen), CTAB surface area = 156-157 m 2 / g;

[0087] 4401, Cognis Chemicals, a-methylstyrene resin, softening point = 85 °C (according to ASTM E 28), T g = 45 °C

[0088] 8115, Cognis Chemicals, non-limonene based terpene resin, softening point = 115 °C (according to ASTM E 28), T g = 66 °C

[0089] g 3,3'-Bis(triethoxysilylpropyl)disulfide (TESPD)

[0090] From the data in Table 1 it is clear that the terpene resin based on biorenewable raw materials is to an extent greater than 95% homopolymerized with the liquid polybutadiene (which is silicone-modified and has an average molecular weight M of 13 600 g / mol as determined by GPC). w The presence of the combination of modified polybutadiene 2(V) and terpene resin 3(V) has the following result: in mixture 4(E), the stress-strain characteristics tensile strength and elongation at break are improved, i.e., increased, unexpectedly to a degree that far exceeds the expected effect of the individual measures (the addition of modified polybutadiene 2(V) and the replacement of α-methyl-styrene resin with terpene resin 3(V)). As a result, mixture 4(E) has high structural durability. In mixture 4(E), the maximum loss factor tan δ at 55°C is max and tan δ (10%) by RPA are also significantly improved, ie, reduced, which results in a reduction in the rolling resistance of the tread of the pneumatic vehicle tire.

Claims

1. A sulphur-crosslinkable rubber mixture, in particular for use in the tread of pneumatic vehicle tyres, comprising at least: - at least one diene rubber, - 5 to 70 phr (based on 100 parts by weight of all rubbers in the mixture) of at least one terpene resin based to an extent of more than 95% on biorenewable raw materials, 1 to 40 phr of at least one liquid polybutadiene, which is silicone-modified and has an average molecular weight M of 500 to 18 000 g / mol by GPC w ,as well as - 40-350 phr of at least one filler.

2. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The rubber mixture contains 20 to 60 phr, preferably 30 to 50 phr, of at least one terpene resin based to an extent of more than 95% on biorenewable raw materials.

3. The sulfur-crosslinkable rubber mixture according to claim 1 or 2, characterized in that The terpene resin is based to an extent of 100% on biorenewable raw materials.

4. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The terpene resin is not limonene based.

5. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The terpene resins are based on α- and β-pinene.

6. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The terpene resin has an average molecular weight M of 800 to 1500 g / mol as determined by GPC. w .

7. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The terpene resin has a softening point of 100 to 140°C, preferably 110 to 130°C.

8. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The terpene resin has a glass transition temperature Tg of 50°C to 100°C, preferably 50°C to 80°C.

9. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The rubber mixture contains 2 to 17 phr of the silicone-modified liquid polybutadiene.

10. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The liquid polybutadiene is silicone modified at the ends and / or along the chain.

11. The sulfur-crosslinkable rubber mixture according to claim 10, characterized in that The organosilicon-modified liquid polybutadiene is terminally modified with triethoxysilane groups.

12. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The silicone-modified liquid polybutadiene has a glass transition temperature T of -85°C to -30°C as determined by DSC. g .

13. The sulfur-crosslinkable rubber mixture according to claim 1, characterized in that The rubber mixture contains 20 to 200 phr of silica as filler.

14. Pneumatic vehicle tire comprising at least one component made from the sulfur-vulcanized rubber mixture according to any one of claims 1 to 13.

15. A pneumatic vehicle tire as claimed in claim 14, having a tread, at least the road contacting portion of the tread being made from the sulfur-vulcanized rubber mixture as claimed in any one of claims 1 to 13.

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