Sulfur-crosslinkable rubber mixture, vulcanizate and vehicle tyre

Abstract

The present invention relates to a sulfur-crosslinkable rubber mixture comprising 40 to 80 phr of at least one polyisoprene, 10 to 40 phr of at least one butadiene rubber that has been amino-functionalized and has a cis content of less than 80%, and 10 to 50 phr of at least one functionalized SBR rubber, to a vulcanizate, to a component part, and to a corresponding vehicle tyre.

Description

[0001] Description

[0002] Sulphur-curable rubber compound, vulcanizate and vehicle tires

[0003] The present invention relates to a sulfur-crosslinkable rubber mixture, a vulcanizate, a component and a corresponding vehicle tire.

[0004] The rubber composition of the tread largely determines the driving characteristics of a tire, especially a pneumatic vehicle tire.

[0005] Likewise, the sulfur-curable rubber compounds used in belts, hoses, and straps, especially in areas subject to high mechanical stress, are largely responsible for the stability and durability of these rubber products. Therefore, these sulfur-curable rubber compounds for pneumatic vehicle tires, belts, and hoses are subject to very high demands.

[0006] Sulphur-curable rubber compounds for the production of treads are known from the state of the art.

[0007] EP2662402B1 describes a mixture of at least two diene rubbers, 0.1-20 phr of a C9 resin, and 0.1-7 phr of another processing agent. It is assumed that the presence of the resin improves the homogeneity of the polymer blend.

[0008] US 2012 / 0289647 describes the improvement of the abrasion behavior of a tread compound without significant deterioration of the rolling resistance and wet braking properties by combining functionalized diene rubber with at least one aliphatic and / or aromatic resin and at least one filler.

[0009] DE102018211763A1 describes a mixture comprising 10-100 phr of at least one amino-functionalized butadiene rubber with a cis content of less than 80% and 25 phr of at least one carbon black. One example of the embodiment contains 40-60 phr of rubber and 60 to 40 phr of at least one polyisoprene, preferably NR, with preferably no third rubber present. Furthermore, an embodiment is disclosed that contains less than 90 phr of rubber and 10 phr of a polyisoprene, preferably 10 phr of NR, as well as a third diene rubber from the group of butadiene rubbers (SSBR, ESBR, and BR).

[0010] EP2853557A1 describes a mixture comprising 5-95 phr of at least one solution-polymerized SBR which is amino-functionalized and whose styrene content is 0.1 to 12 wt.% and which, in the unvulcanized state, has a glass transition range of -75 to -120°C, 5-95 phr of at least one further diene rubber, and 20 to 150 phr of at least one carbon black. According to a further preferred embodiment, the above-mentioned amino-functionalized SSBR is mixed with a high T g SSBR (T g = -40 to +10°C), whereby a natural and / or synthetic polymer may be present.

[0011] In summary, however, known blends comprising three rubbers (triblends), such as NR, (functionalized) SSBR, and standard BR (e.g., Nd-BR), as well as other rubbers known to those skilled in the art, no longer meet current requirements for wet grip and rolling resistance properties while maintaining high abrasion and durability. Furthermore, crack and cut resistance ("chip & chunk"), in particular, requires improvement.

[0012] Likewise, mixtures of two rubbers (diblends), comprising polyisoprene (natural and / or synthetic) and an amino-functionalized BR, do not meet the above requirements.

[0013] It was therefore the object of the present invention to provide a sulfur-crosslinkable rubber mixture, in particular for producing a tread for a vehicle tire, which overcomes the disadvantages of the prior art and, in particular, provides improved crack and cut resistance while simultaneously providing high abrasion and rolling resistance properties. In particular, the crack and cut resistance should be improved over the course of use (after aging).

[0014] Other properties (such as abrasion and wet grip, rolling resistance and processability) of the sulfur-curable rubber compound should preferably remain at least at a comparable level or even be improved.

[0015] If, in the context of the present application, the improvement of properties of the sulfur-crosslinkable rubber mixture is mentioned, this refers analogously to the improvement of the properties of a vulcanizate obtained from the sulfur-crosslinkable rubber mixture.

[0016] The present object was surprisingly achieved by a sulfur-crosslinkable rubber mixture according to claim 1, ie by a sulfur-crosslinkable rubber mixture comprising

[0017] - 40 to 80 phr of at least one polyisoprene,

[0018] - 10 to 40 phr of at least one butadiene rubber which is amino-functionalized and has a cis content of less than 80%, and

[0019] - 10 to 50 phr of at least one functionalized SBR rubber, preferably a functionalized SSBR rubber.

[0020] Surprisingly, it has been found that the combination of the above-mentioned components, in particular the combination of the three specific rubbers, achieves improved crack and cut resistance combined with high abrasion and wet grip properties. Furthermore, crack and cut resistance, in particular, is improved after aging. Other properties remain at a good level or are also improved, making such a sulfur-crosslinkable rubber mixture particularly advantageous for use in vehicle tires. The present invention further relates to a vulcanizate obtained by the sulfur vulcanization of at least one sulfur-crosslinkable rubber mixture, as defined above.

[0021] A further subject of the present invention relates to a component comprising such a vulcanizate.

[0022] A further subject of the present invention relates to a vehicle tire comprising at least one such component.

[0023] In the case of two-part treads (upper part: cap and lower part: base), the sulfur-crosslinkable 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 sulfur-crosslinkable rubber mixture according to the invention.

[0024] The sulfur-crosslinkable rubber mixture according to the invention is also suitable for treads consisting of different tread mixtures arranged side by side and / or one below the other (multi-component treads).

[0025] For the purposes of the present invention, vehicle tires are preferably understood to mean pneumatic vehicle tires and solid rubber tires, including tires for industrial and construction vehicles, truck tires, passenger car tires, and two-wheeler tires. Pneumatic truck tires are particularly preferred.

[0026] The sulfur-crosslinkable 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. The present invention further relates to the use of a sulfur-crosslinkable rubber mixture or a vulcanizate, each as defined above, for producing a technical rubber article, such as vehicle tires, in particular a tread and / or a sidewall for a vehicle tire, bellows, conveyor belts, air springs, belts, straps, or hoses, as well as shoe soles.

[0027] 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, the component according to the invention, and the vehicle tire according to the invention, as well as the use according to the invention.

[0028] Advantageous further developments are described in the subclaims.

[0029] Numerous specific details are discussed below to provide a thorough understanding of the subject matter. However, it will be apparent to one skilled in the art that the subject matter can be practiced and recreated without these specific details.

[0030] All features of one embodiment may be combined with features of another embodiment if the features of the different embodiments are compatible.

[0031] Throughout this description and the claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. The reverse is also true, meaning that the plural forms also include the singular forms. It is also understood that the term "and / or," as used herein, refers to and includes all possible combinations of one or more of the associated listed elements. It is further understood that the terms "includes," "including," "comprises," and / or "comprising," when used in this description and the claims, specify the presence of the specified features, steps, operations, elements, components, and / or groups, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0032] 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 (gel permeation chromatography) of greater than 20,000 g / mol.

[0033] The sulfur-curable rubber compound contains 40 to 80 phr of at least one polyisoprene.

[0034] The polyisoprene can preferably be synthetic polyisoprene (IR) and / or polyisoprene of natural origin (NR).

[0035] The polyisoprene 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 sulfur-crosslinkable rubber mixture contains 50 to 70 phr, particularly preferably 55 to 65 phr, most preferably 58 to 62 phr of at least one polyisoprene (most preferably this applies to a natural polyisoprene (NR)).

[0038] The sulfur-curable rubber mixture further contains 10 to 40 phr of at least one butadiene rubber which is amino-functionalized and has a cis content of less than 80%.

[0039] In the context of the present application, "amino-functionalized" means that the rubber bears 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 bear one or more amino groups.

[0040] 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%.

[0041] 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 (RH), the amino group is a primary amino group. If one additional residue is a hydrogen atom and the other is not a hydrogen atom, the amino group is a secondary amino group. If both residues are not hydrogen atoms, the amino group is a tertiary amino group.

[0042] In the context of the present invention, in principle all amino groups are conceivable as functionalization of the butadiene rubber.

[0043] 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.

[0044] 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%.

[0045] 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: CDClb).

[0046] The butadiene rubber contained according to the invention has a cis content of less than 80%, preferably in the range of 20 to 80%.

[0047] According to advantageous embodiments of the invention, the cis content of the amino-functionalized butadiene rubber B is 20 to 60%, preferably 30 to 50%.

[0048] The butadiene rubber 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.

[0049] According to an advantageous embodiment of the invention, the sulfur-crosslinkable rubber mixture contains 15 to 30 phr, more preferably 15 to 25 phr, and particularly preferably 18 to 22 phr of the amino-functionalized butadiene rubber. Butadiene rubber is known to be a diene rubber, which makes the rubber mixture according to the invention sulfur-crosslinkable.

[0050] 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.

[0051] The sulfur-curable rubber compound also contains 10 to 50 phr of at least one functionalized SBR rubber.

[0052] The functionalized SBR rubber is preferably a solution-polymerized styrene-butadiene rubber (SSBR).

[0053] Preferably, it has a styrene content of 8 to 20%, preferably of 10 to 20%, particularly preferably of 12 to 18% and / or (preferably and) a vinyl content of 25 to 45%, preferably of 25 to 40%, preferably of 27 to 35%.

[0054] The SBR rubber is preferably functionalized with carbon black and / or silica, particularly preferably with at least carbon black. The SBR rubber is preferably functionalized with carbon black and silica. This particularly applies to the preferred SSBR.

[0055] The functionalized SBR rubber (preferably SSBR rubber) used in the mixture preferably has one or more than one functionalization, preferably selected from the group consisting of silane sulfide groups, amino groups, hydroxyl groups, epoxy groups, siloxane groups, phthalocyanine groups, and carboxy groups; more preferably consisting of silane sulfide groups and amino groups, very particularly preferably it is a functionalization with silane sulfide groups. Particularly preferred silane sulfide groups are known from WO 2007 / 047943 A2. Particularly preferred amino groups are aminosilane groups (i.e. amino groups which are preferably bonded to a silicon atom via a spacer), which are preferably each either protected or unprotected. Preferred amino groups are known from WO 03 / 029299 A1 and WO 2008 / 123164 A1.

[0056] The one or more functionalizations preferably cause an interaction with the fillers contained in the mixture, preferably with carbon blacks.

[0057] The SBR rubber, preferably the SSBR rubber, has in particular a low T g , preferably less than -50°C, preferably less than -55°C. Particularly preferably, the T g in the range from -85 to -50°C, preferably from -80 to -50°C, more preferably from -75 to -55°C, most preferably from -70 to -55°C.

[0058] Particularly suitable SSBR rubbers preferably comprise 13 to 18% styrene and 27 to 33% vinyl and further have a T g in the range of -63 to - 58°C.

[0059] Unless otherwise stated, the T g determined by DSC according to ISO 22768(2020E).

[0060] In a further preferred embodiment, the sulfur-crosslinkable rubber mixture according to the invention is preferably characterized in that the sulfur-crosslinkable rubber mixture further contains at least one filler.

[0061] Suitable fillers include carbon black, graphite, graphene, and so-called "carbon-silica dual-phase fillers," chalk, starch, magnesium oxide, titanium dioxide, or rubber gels, as well as fibers (such as aramid fibers, glass fibers, carbon fibers, and cellulose fibers). One or more carbon blacks are particularly preferred as fillers.

[0062] Zinc oxide, preferably contained in the rubber mixture according to the invention, is not considered a filler in the context of the present invention. Preferably, the at least one filler comprises a carbon black having an iodine adsorption number according to ASTM D 1510 of 80 to 180 g / kg and / or a DBP number according to ASTM D 2414 of 110 to 200 ml / 100 g.

[0063] The sulfur-crosslinkable rubber mixture particularly preferably contains at least one carbon black 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 / or 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.

[0064] Particularly preferably, and for example, the sulfur-crosslinkable rubber mixture contains carbon blacks of ASTM type N 121 and / or N 220.

[0065] In a sulfur-curable rubber compound containing amino-functionalized BR and functionalized SBR, preferably functionalized SSBR, a surprising significant improvement (increase) in crack and cut resistance in tire use of 10% is achieved compared to a diblend of polyisoprene and amino-functionalized BR.

[0066] The amount of at least one carbon black is preferably 25 to 100 phr, particularly preferably 30 to 100 phr, again preferably 35 to 70 phr and according to a very particularly preferred embodiment 45 to 60 phr.

[0067] The quantity of at least one soot means, in the case of two or more soots, the total quantity.

[0068] Furthermore, the sulfur-crosslinkable rubber mixture may contain other carbon blacks known in the art that do not contribute to the amount of carbon black defined above. Other carbon blacks may be added as additional fillers, but preferably in comparatively small amounts, such as 0.1 to 5 phr.

[0069] If other fillers are included in addition to carbon black, these are preferably contained in an amount of 0.1 to 50 phr.

[0070] Preferably, the sulfur-crosslinkable rubber mixture according to the invention contains carbon black as the sole filler or as the main filler, which means that the amount of carbon black is significantly greater than the amount of any other fillers present.

[0071] In a further embodiment, the sulfur-crosslinkable rubber mixture is preferably characterized by being substantially free of added silica and / or silane. Silica is synonymous here with silicic acid.

[0072] By “essentially free” it is preferably understood that the added silica and / or silane is present in an amount of less than 4 phr, preferably less than 2 phr, in the sulfur-curable rubber mixture.

[0073] In particular, the sulfur-curable rubber compound is free (except for unavoidable impurities) of added silica and / or (preferably and) silane.

[0074] Avoiding added silica and / or (preferably and) silane has a positive effect on abrasion resistance.

[0075] In one embodiment, the sulfur-crosslinkable rubber mixture is preferably characterized in that the sulfur-crosslinkable rubber mixture comprises less than 5 phr, preferably less than 3 phr, of plasticizer, in particular oil. Reducing the amount of plasticizer, in particular oil, has a positive effect on abrasion resistance.

[0076] 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 liquid polymers whose average molecular weight (determined by GPC = gel permeation chromatography, based on BS ISO 11344:2016) is between 500 and 20,000 g / mol. If additional liquid polymers are used as plasticizers in the sulfur-crosslinkable rubber mixture according to the invention, these are not included as rubber in the calculation of the composition of the polymer matrix.

[0077] The plasticizer is preferably selected from the group consisting of the above-mentioned plasticizers.

[0078] The plasticizer is particularly preferably selected from the group consisting of liquid polymers and mineral oils.

[0079] When using mineral oil, it is preferably selected from the group consisting of DAE (Distilled Aromatic Extracts), RAE (Residual Aromatic Extracts), TDAE (Treated Distilled Aromatic Extracts), MES (Mild Extracted Solvents), and naphthenic oils.

[0080] In one embodiment, the sulfur-crosslinkable rubber mixture is preferably characterized in that the sulfur-crosslinkable rubber mixture is substantially free of resins, in particular hydrocarbon resins. "Substantially free" preferably means that the amount of resins, in particular hydrocarbon resins, present is less than 2 phr, preferably less than 1 phr, in particular less than 0.5 phr.

[0081] In particular, the sulfur-curable rubber compound is free (except for unavoidable impurities) of resins, especially hydrocarbon resins.

[0082] 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.

[0083] In particular, the hydrocarbon resin is selected from the group consisting of aliphatic C5 resins and hydrocarbon resins of alpha-methylstyrene and styrene and 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.

[0084] Such hydrocarbon resins should be avoided in particular. Avoiding resins, especially hydrocarbon resins, has a positive effect on abrasion resistance.

[0085] The vulcanizate according to the invention is obtained by vulcanization. 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.

[0086] Sulfur and / or other sulfur donors as well as one or more accelerators are preferably added in a final mixing step of the sulfur-curable rubber mixture.

[0087] The accelerator is preferably selected from the group consisting of thiazole accelerators, mercapto accelerators, sulfenamide accelerators, thiocarbamate accelerators, thiuram accelerators, thiophosphate accelerators, thiourea accelerators, xanthate accelerators, and guanidine accelerators.

[0088] Preference is given to using at least one sulfenamide accelerator selected from the group consisting of N-cyclohexyl-2-benzothiazolesufenamide (CBS), N,N-dicyclohexylbenzothiazole-2-sulfenamide (DCBS), benzothiazyl-2-sulfenemorpholide (MBS), and N-tert-butyl-2-benzothiazylsulfenamide (TBBS).

[0089] In particular, the vulcanization accelerator includes N-cyclohexyl-2-benzothiazolesufenamide (CBS).

[0090] It is preferred that the vulcanizate obtained by vulcanizing the sulfur-curable rubber mixture has a low degree of crosslinking. This results from the low dosage of sulfur and / or sulfur-donating substances and vulcanization accelerators and is recognizable by increased elongation at break values.

[0091] Therefore, the amount of vulcanization accelerator contained, in particular N-cyclohexyl-2-benzothiazolesufenamide (CBS), is less than 2 phr, in particular less than 1.5 phr, very particularly less than 1.3 phr, particularly preferably with a sulfur amount of less than 1.5 phr or less than 1.3 phr or less than 1.1 phr.

[0092] All sulfur-donating substances known to the person skilled in the art can be used as the sulfur-donating substance. If the sulfur-crosslinkable rubber mixture contains a sulfur-donating substance, this is preferably selected from the group comprising, for example, thiuram disulfides, such as, for example, tetrabenzylthiuram disulfide (TBzTD) and / or tetramethylthiuram disulfide (TMTD) and / or tetraethylthiuram disulfide (TETD), and / or thiuram tetrasulfides, such as, for example, dipentamethylenethiuram tetrasulfide (DPTT), and / or dithiophosphates, such as, for example, B. 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.

[0093] 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 sulfur-curable rubber compound. This system contains a vulcanizing agent that crosslinks with a functionality greater than four and at least one vulcanization accelerator.

[0094] The required amount of additional sulfur in the form of elemental sulfur and / or additional sulfur donor depends on the application of the respective sulfur-curable rubber compound. The respective amounts to be added are known to those skilled in the art. When adding elemental sulfur in a sulfur-curable rubber compound for the bead of vehicle tires, for example, the amounts range from 0 to 5 phr (where the value 0 is just excluded). 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 (where the value 0 is just excluded).

[0095] Furthermore, the amount of sulfur is preferably less than 1.5 phr or less than 1.3 phr or less than 1.1 phr (but in all cases preferably greater than 0).

[0096] In addition, vulcanization retarders such as CTP (N-(cyclohexylthio)phthalimide) may be present in the sulfur-curable rubber compound.

[0097] The terms “vulcanized” and “crosslinked” are used synonymously in the context of the present invention.

[0098] Furthermore, the sulfur-curable 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

[0099] - 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),

[0100] - Activators such as zinc oxide and fatty acids (e.g. stearic acid) and / or other activators such as zinc complexes such as zinc ethylhexanoate,

[0101] - Waxes,

[0102] - Mastication aids, such as 2,2'-dibenzamidodiphenyl disulfide (DBD) and

[0103] - Processing aids, such as, in particular, fatty acid esters and metal soaps, such as zinc soaps and / or calcium soaps. 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.

[0104] The total amount of other additives may include, in particular, zinc oxide (ZnO).

[0105] This can be any type of zinc oxide known to the person skilled in the art, such as ZnO granules or powder. The zinc oxide commonly used 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.

[0106] Zinc oxide is preferably present in an amount of 1 to 5 phr, in particular 3 phr.

[0107] The present invention further relates to a vulcanizate obtained by the sulfur vulcanization of at least one sulfur-crosslinkable rubber mixture as described above.

[0108] Vulcanization is generally understood to mean the conversion of plastic, rubber-like, unsaturated, or saturated polymers into a rubbery, elastic state by crosslinking them with sulfur or sulfur compounds. The individual polymer chains are irreversibly bonded together by covalent bonds. The resulting product is the vulcanizate, especially the sulfur vulcanizate.

[0109] The present invention further relates to a component comprising the vulcanizate as described above.

[0110] The present invention further relates to a vehicle tire comprising at least one vulcanizate as described above in at least one component. The present invention further relates to a vehicle tire, wherein the component as described above is a tread, in particular a tread with a ribbed profile, and / or a sidewall.

[0111] A vehicle tire is, in particular, a tire for a commercial vehicle, such as a truck or a bus.

[0112] The sulfur-crosslinkable rubber mixture described above is particularly suitable for the production of and use in vehicle tires, in particular pneumatic vehicle tires. Therefore, the vehicle tire according to the invention is preferably a pneumatic vehicle tire.

[0113] In principle, the application is conceivable in all tire components, in particular in a tread, especially in the cap of a tread with a cap / base construction, as already described above.

[0114] For the production of or use in vehicle tires, the mixture is preferably formed into a tread shape as a ready-mix before vulcanization and applied as known during the production of the green vehicle tire.

[0115] The sulfur-curable 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 sulfur-curable rubber mixture for one or more different body mixtures are then used to construct a green tire.

[0116] The body mixture used here is the sulfur-crosslinkable rubber mixture for the other components of a tire, such as the separator plate, inner liner (inner layer), apex, belt, shoulder, belt profile, carcass, bead reinforcement, bead profile, flange profile, and bandage. The present invention further relates to the use of a sulfur-crosslinkable rubber mixture or a vulcanizate, each as described above, for producing a technical rubber article, such as vehicle tires, in particular a tread, in particular a tread with a ribbed profile and / or a sidewall for a vehicle tire, bellows, conveyor belts, air springs, belts, straps, or hoses, as well as shoe soles.

[0117] For use of the sulfur-crosslinkable rubber mixture according to the invention in belts and straps, particularly conveyor belts, the extruded, still unvulcanized mixture is preferably formed into the appropriate shape and, during or after the process, is 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 sulfur-crosslinkable 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 sulfur-crosslinkable rubber mixture.

[0118] The invention will now be explained in more detail using non-limiting comparative and exemplary embodiments.

[0119] Examples

[0120] Otherwise, the compound was produced according to the process customary in the rubber industry under standard conditions in three stages in a laboratory mixer with a volume of 300 milliliters to 3 liters. In the first mixing stage (basic mixing stage), all components except the vulcanization system (sulfur and vulcanization-influencing substances) were mixed for 200 to 600 seconds at 145 to 165 °C, with target temperatures of 150 to 160 °C. In the second stage, the mixture from the first mixing stage was mixed again. The final mixture was created by adding the vulcanization system in the third stage (final mixing stage), which was mixed for 180 to 300 seconds at 90 to 120 °C.Test specimens were produced from all mixtures by vulcanization according to t95 (measured on a moving die rheometer according to ASTM D 5289-12 / ISO 6502) under pressure at 140°C and with these test specimens, material properties typical for the rubber industry were determined using the test methods specified below.

[0121] • Shore A hardness at room temperature using a durometer according to DIN ISO 484:2018

[0122] • Rebound resilience at 70 °C and room temperature (RT) according to ISO 4662 or ASTM D1054

[0123] • Tensile strength, elongation at break and stress value at 300% elongation (modulus 300, M300) at room temperature (RT) according to DIN 53 504

[0124] • Chip % Chunk Performance and Aging:

[0125] Chip & Chunk resistance is tested in road tests with tires in size 205 / 75 R17.5 CHS3 124 L on rough gravel roads over a distance of approximately 1,000 km. The compound candidates are then visually evaluated for damage severity in direct comparison.

[0126] The reference is set to 100 – better damage patterns are indicated by values ​​higher than 100, and deterioration by lower values. To evaluate the effect of field aging, a second set of tires for the C&C vehicle test is stored in an oven at 65°C for 28 days. The comparison compounds are designated V, and the compound according to the invention is designated E.

[0127] Table 1 : Substances used from Table 1: a) natural polyisoprene b) Amino BR: butadiene rubber, amino-functionalized, cis content less than 80%: BR500, ENEOS Corporation c) SSBR: Sprintan® SLR 3402, Synthos Group; 15% styrene and 30% vinyl content; Tg -62°C d) Carbon blacks of ASTM type N 121 e) Carbon blacks of ASTM type N 220 f) Silica VN3, Evonik

[0128] The evaluation shows that the sulfur-crosslinkable rubber mixture according to the invention, as a mixture of three rubbers (triblend), two of which are functionalized in such a way that the interaction between polymer and carbon black is improved, leads to a vulcanizate with increased tensile strength and elongation at break, whereas the comparison mixture V1 is at the level of the state of the art of the diblend.

[0129] Furthermore, an improvement in Chip & Chunk (C&C) performance is achieved in use.

[0130] Although the SSBR is largely T g-is the same as NR, and thus has the same hysteresis as NR and therefore the energy absorption capacity should be the same between NR and SSBR, it was surprisingly found that the use of the triblend improved the chip and chunk resistance (delta approx. 10%).

[0131] Additionally, advantages are evident after aging, as the 300 modulus of the sulfur-curable rubber compound with two rubbers (diblend) can no longer be measured. The triblend shows an increase of approximately 50%, while the value is no longer determinable in the diblend. In tire tests, a more significant advantage of approximately 23% is now evident after aging.

[0132] Thus, with the sulfur-crosslinkable

[0133] Rubber compounds make it possible to obtain vulcanizates in the form of vehicle tires, whereby the cut and crack resistance is further improved, while the other properties are at a very good level.

[0134] A vehicle tire according to the invention, which has at least one vulcanizate of the sulfur-crosslinkable rubber mixture according to the invention in at least one component, in particular the tread, is optimized with regard to durability with regard to the overall level of the other requirements of rolling resistance, abrasion and handling.

[0135] A vehicle tire according to the invention, which has at least one vulcanizate of the sulfur-crosslinkable rubber mixture according to the invention in at least one component, in particular the tread, shows improved damping and improved wet braking (better grip) due to the lower rebound resilience.

[0136] In particular, such a vehicle tire, which has at least one vulcanizate of the sulfur-crosslinkable rubber mixture according to the invention in at least one component, in particular the tread, is optimized with regard to chip & chunk performance.

Claims

Patent claims 1. Sulphur-curable rubber mixture comprising - 40 to 80 phr of at least one polyisoprene, - 10 to 40 phr of at least one butadiene rubber which is amino-functionalized and has a cis content of less than 80%, and - 10 to 50 phr of at least one functionalized SBR rubber.

2. Sulphur-crosslinkable rubber mixture according to claim 1, characterized in that the cis content of the amino-functionalized butadiene rubber is 20 to 60%, preferably 30 to 50%.

3. Sulphur-crosslinkable rubber mixture according to claim 1 or 2, characterized in that the at least one functionalized SBR rubber has a T g of less than -50°C, preferably less than -55°C.

4. Sulfur-crosslinkable rubber mixture according to any one of the preceding claims, characterized in that the sulfur-crosslinkable rubber mixture further contains at least one filler, preferably a carbon black, which has an iodine adsorption number according to ASTM D 1510 of 80 to 180 g / kg and / or a DBP number according to ASTM D 2414 of 110 to 200 m 1 / 100 g.

5. Sulfur-crosslinkable rubber mixture according to any one of the preceding claims, characterized in that the sulfur-crosslinkable rubber mixture is substantially free of added silica and / or silane.

6. Sulfur-crosslinkable rubber mixture according to any one of the preceding claims, characterized in that the sulfur-crosslinkable rubber mixture comprises less than 5 phr, preferably less than 3 phr of plasticizer, in particular oil.

7. Sulphur-crosslinkable rubber mixture according to any one of the preceding claims, characterized in that the sulfur-crosslinkable rubber mixture is substantially free of resins, in particular hydrocarbon resins.

8. Sulphur-crosslinkable rubber mixture according to any one of the preceding claims, characterized in that the sulfur-crosslinkable rubber mixture contains less than 2 phr, in particular less than 1.5 phr, most preferably less than 1.3 phr of a vulcanization accelerator, particularly preferably with a sulfur amount of less than 1.5 phr or less than 1.3 phr or less than 1.1 phr, 9. Vulcanizate obtained by the sulfur vulcanization of at least one rubber mixture according to one of claims 1 to 8.

10. Component comprising the vulcanizate according to claim 9.

11. Vehicle tire, characterized in that it comprises at least one vulcanizate according to claim 9 in at least one component.

12. Vehicle tire according to claim 1, characterized in that the component is a tread, in particular a tread with a ribbed profile, and / or a sidewall.

13. Use of a rubber mixture according to one of claims 1 to 8 or of a vulcanizate according to claim 9 for producing a technical rubber article, such as vehicle tires, in particular a tread, in particular a tread with a ribbed profile and / or a sidewall for a vehicle tire, bellows, conveyor belts, air springs, belts, straps or hoses, and shoe soles.

Images