Stabilized rubber composition providing protection against ozone

Abstract

A rubber composition having a good antiozonation performance, particularly without the need for the use of 6PPD. Such a rubber composition is suitable for rubber articles, which include, besides sealings and gaskets, especially vehicle tires, such as rubber pneumatic tires, solid tires and non-pneumatic tires, and as well general rubber products that are exposed to continuous and intermittent dynamic operation conditions and require protection from ozonation like belts, hoses, cables, automotive mounts and bushings. In the rubber composition, the antiozonant compound is a N-heteroaromatic diaminoaryl compound of formula (II), wherein X1 to X8, R1, R1' and R2 are defined as in the description, and which is used to protect rubber composition from ozonation and consecutively from the damaging effect caused to the rubber composition by ozonation.

Description

[0001] BASF SE 240613

[0002] 1

[0003] Stabilized rubber composition providing protection against ozone

[0004] FIELD OF THE INVENTION

[0005] The present invention described herein in the following relates to rubber compositions and, more particularly, to tire rubber compositions having a good antiozonation performance, and particularly having good antiozonation performance without the need for the use of 6PPD. The rubber compositions according to the present invention are particularly suitable for rubber articles, which include, besides sealings, windscreen wipers and gaskets, especially vehicle tires, such as rubber pneumatic tires, solid tires and non-pneumatic tires, and as well general rubber products that are exposed to continuous and intermittent dynamic operation conditions and require protection from ozonation like belts, hoses, cables, automotive mounts and bushings. The invention relates as well to the use of antidegradant compounds defined hereinafter to protect rubber compositions from ozonation and consecutively from the damaging effect caused to the rubber composition caused by ozonation and to new N-heteroaromatic diaminoaryl derivatives for described use.

[0006] BACKGROUND OF THE INVENTION

[0007] Tires, such as vehicle tires, and other articles that are made of rubber, are manufactured from rubber compositions that include rubber, e.g., natural rubber, synthetic rubber or combinations thereof, reinforcing fillers, vulcanizing agents, and other components that improve the physical mechanical characteristics of both the uncured and the cured rubber compositions.

[0008] Natural rubber and synthetic polymers (such as IR, BR, SSBR, ESBR, etc.), but also natural and synthetic oils, fats and lubricants, are subject to oxidation reactions which have a disadvantageous effect on the original desired properties during prolonged storage and during the use phase in the target application, which often involves exposure to elevated temperatures. Depending on the type of polymer, the polymer chains are either shortened, up to a liquefaction of the material, or the crosslink density of the material increases. Both processes are unwanted and need to be prevented to ensure long-term consistency of the material properties. Antidegradants like antioxidants and antiozonants therefore contribute significantly to the longevity of vehicle tires and other technical rubber articles. They can react with ozone and deactivate radical species, such as, e.g., alkyl radicals, ally radicals, hydroxyl radicals, hydroperoxyl radicals, and alkylperoxy radicals, and thus protect the rubbers from degradation reactions. Antidegradants which react in particular with ozone and are able to protect the rubber from the detrimental effects of ozone are also referred to as "antiozonant agents" or "antiozonants".

[0009] If rubber articles based on highly unsaturated elastomers remain unprotected, ozone, which is present in the environment, will attack the surface of the rubber material. This ozone attack will BASF SE 240613

[0010] 2 result in cracks on the surface of the rubbers, particularly if the rubber is under strain during usage. Those initial cracks can further develop into deep and large cracks, especially when the rubber article is subject to dynamic load conditions. Such deep and large cracks may not only shorten the service life of the rubber articles such as tires but may as well - in extreme cases - eventually lead to mechanical failure and thereby pose safety issues of the rubber article in use. Different standards like DIN, ISO, VDE, SAE, and ASTM describe static (“static ozone cracking test”) and dynamic methods (“dynamic ozone cracking test”) for the investigation of the behavior of rubber samples towards ozone. Usually, rubber samples are stretched, and ozone is applied at defined temperature, humidity, and air velocity. When the surface ozone cracks of the “comparative rubber formulation part” are graded, a normalized cracking index can be calculated. For dynamic ozone cracking testing, the samples are additionally subjected to a cyclic strain in the ozone chamber. To combat the ozone attack on rubber, various antiozonants have been developed and commercialized in the past to slow down the formation of the ozone-induced cracks under static and dynamic conditions. For example, waxes of various characteristics have been developed and used in rubbers against static ozone attack by forming a film barrier on the surface. However, such film will break and lose its protective properties against ozone under dynamic conditions.

[0011] For dynamic protection, various chemical antiozonants have been developed and are commercially available, with one of the well-known and widely used groups being the substituted para- phenylenediamines (PPDs), wherein 6PPD ( / \ / -1 ,3-dimethylbutyl- / \ / -phenyl-p-phenylenediamine [CAS number: 793-24-8]) is one of its most popular representatives. The PPD “family” further includes, e.g., I PPD ( / V-isopropyl- / V-phenyl-p-phenylenediamine), 7PPD ( / V-(1 ,4-dimethylpen- tyl)- / V'-phenyl-p-phenylenediamine), 77PD ( / V, / V'-bis(1 ,4-dimethylpentyl)-p-phenylenediamine), 44PD ( / V, / V'-di-sec-butyl-p-phenylenediamine) and 8PPD ( / \ / -(1-methylheptyl)- / \ / -phenyl-p-phe- nylenediamine).

[0012] The group of PPDs may also include derivatives such as / V-cyclohexyl-A / '-phenyl-p-phenylenedi- amine (CHPPD), / V, / V'-diphenyl-p-phenylenediamine (DPPD), / V, / V'-ditolyl-p-phenylenediamine (DTPD) or SPPD ( / V-(1-phenylethyl)- / V-phenyl-p-phenylenediamine).

[0013] Yet another group of chemicals selected from quinones (Q), quinoneimines (QI), and quinonediimines (QDI) based on PPD chemistry have been reported in rubber formulations. US6,533,859 discloses a method to pretreat carbon black surface with such chemicals to improve the dispersibility of the carbon black and the dynamic properties of the rubber formulations.

[0014] EP1025155 teaches a process to improve the processability of uncured rubber through high temperature mixing of quinonediimine, natural rubber, and carbon black.

[0015] US8,207,247 teaches a process to mix a rubber composition comprising natural rubber and an additive selected from aforementioned chemicals, preferably a quinonediimine. BASF SE 240613

[0016] 3

[0017] Recently, WO 2022 / 069001 disclosed phenothiazine compounds, their use in rubber blends and vehicle tires as antiozonant.

[0018] And WO 2022 / 146441 discusses rubber compositions having improved antiozonation performance comprising hydroxyl-substituted PPDs, which are particularly suitable for rubber articles such as tires.

[0019] It is known that the PPDs can also act as primary and secondary antioxidants by scavenging free radicals and converting hydroperoxides into less harmful intermediates.

[0020] If additives have low solubility in the rubber, they can easily migrate to the surface, leading to blooming. Some antidegradants, such as IPPD, are partially poorly soluble in rubbers (or have poor compatibility) and thus have a pronounced tendency to migrate to the surface and form a visible film there. This effect is known under the name "blooming", meaning that the antidegradant “blooms” from the respective rubber. Blooming can occur during and after the curing process, either as a relatively fast process or only after prolonged storage or use. For instance, high humidity can promote the exudation of additives, and chemical substances like oxygen and ozone can react with rubber components, leading to surface changes and blooming. This phenomenon can appear uniformly or in localized areas, affecting both the appearance and performance of the product. The presence of a bloom may affect the adhesion properties of rubber components, especially in applications requiring strong bonds. But also the visual appearance of rubber goods such as tires can be negatively impacted by blooming of rubber additives. Hence, new additives with low migration are desired. These new materials can maintain rubber performance while significantly reducing the risk of blooming.

[0021] During the service life of rubber compositions comprising antiozonants of the PPD type, when these antiozonants in general (with certain exceptions) migrate to the surface, they react with and provide protection against ozone in the environment, such as in the case of tire sidewalls and treads. The loading of the antiozonant and its migration rate to the surface therefore influence the service life of the rubber articles. Obviously, the better and faster the migration to the surface, the better the initial protection. On the other side, the fixed loading of the antiozonant and an “unregulated”, meaning too fast migration of the antiozonant to the surface will not only negatively impact the long-term protection, but leads to surface leaching and / or volatilization as well, causing “staining” of the article due to excessive surface concentration.

[0022] These phenomena may be used for assessing the efficacy of antiozonant in general. Antiozonant migration and anti-ozonation longevity tests are factors which assess the efficacy by grading the surface ozone cracks on rubber samples after exposure to ozone environment. The migration rate in this process is dependent on various factors such as the molecular weight and structure of the antiozonant, the solubility and affinity of the antiozonant in the rubber formulation matrix, as well as the environmental conditions. BASF SE 240613

[0023] 4

[0024] In addition, PPDs are also prone to discoloration, which aggravates the visual effects of migration and staining. For example, if a staining antiozonant is used in a black rubber composition which is in proximity to a light-colored rubber part, the staining antiozonant will migrate into the light-colored rubber part and cause discoloration, which represents another problem of PPDs to be addressed.

[0025] Different kind of compounds and solutions have been evaluated in this regard up to now. For instance, US5,047,530 teaches the preparation and use of a larger molecule, substituted triazine for longer-lasting and non-staining ozone protection. Still, the molecule itself is prone to discoloration and therefore not suitable for use in light-colored rubber compositions.

[0026] WO 2023 / 001339 discusses a rubber blend containing substituted indole derivatives for vehicle tires and their use as ageing protectant and / or antiozonant and / or dye.

[0027] WO 2023 / 235855 discloses quinoline compounds as antidegradant compounds, as well as compositions comprising thereof, vulcanized elastomeric articles, lubricant compositions, combustible fuel compositions and fuel additive compositions. Described is also a process for retreading tires using a composition described herein.

[0028] WO2024137665 discloses rubber compositions with antidegradant compounds, including heteroaryl and diarylamine derivatives, as alternatives to 6PPD, which it seeks to replace. Nevertheless, although the scope disclosed is extremely large, it fails to specify the unique / V-het- eroaromatic para-diamino-heteroaryl substitution patterns of the present invention, nor does it address environmental safety profiles. WO2024206786 from same applicant provides likewise a broad class of heteroaryl diamine compounds (bis(alkyl)-substituted pyridine, pyrimidine, pyrazine, pyridazine diamines) as antidegradants but fails as well to specify the unique / V- heteroaromatic para-diamino-heteroaryl substitution patterns of the present invention. Nor are indications to be found with respect to improvements of environmental toxicity, which would be supported by QSAR-based toxicity predictions and experimental validation.

[0029] CN118146144 claims some specific aminopyridine compounds as antidegradents for rubber compositions, particularly for tires, which are however structurally distinct from the / V- heteroaromatic para-diamino-heteroaryl of the present invention.

[0030] LIS20180022729 and LIS20140206585 disclose both substituted heteroaromatic diarylamines as antioxidants for organic substrates, which differ from the / V-heteroaromatic para-diamino-het- eroaryl compounds of the present invention and which do not refer to any antiozonant activity and efficacy in rubber compositions.

[0031] A review of chemical antiozonants for rubber focusing on substituted p-phenylenediamines (PPDs) and their structure-activity relationships in “Rubber World - The Development of New Antiozonants” by Bertrand et al. in 1985 discusses molecular modifications and alternative nonstaining families. Compounds according to the present invention are not covered or suggested in this review of PPDs and related chemistries BASF SE 240613

[0032] 5

[0033] Rubber compositions comprising partially hydrogenated quinoline derivatives especially suitable for rubber articles, like sealings and gaskets and especially vehicle tires, such as rubber pneumatic tires, solid tires and non-pneumatic tires, and as well general rubber products that are exposed to continuous and intermittent dynamic operation conditions and require protection from ozonation are described in WO2025 / 026795.

[0034] Another group of chemicals, hindered phenols, for example, 2,2'-methylenebis(4-methyl-6-tert- butylphenol), are often used as antioxidants in rubber compositions, even though they apparently offer no protection against ozone attack. Since these hindered phenols are generally nonstaining, they are often compounded in light colored articles where staining should be minimized, such as white sidewalls and colored treads in tires.

[0035] However, those hindered phenols are very efficient antioxidants but typically have limited effectiveness in protecting degradation of rubber compositions from ozone attack.

[0036] In general, it can be said, that compounds showing an excellent antioxidant performance do not necessarily also provide protection from ozone. Hence, it cannot be predicted that a high antioxidant efficiency correlates with a relevant antiozonant performance.

[0037] The literature confirms that antioxidants, which can be used to prolong the lifetime of a rubber article under flexing conditions do not necessarily work as antiozonants, i.e., they do not necessarily protect against the destructive influence of ozone on rubbers.

[0038] It has been explicitly acknowledged decades ago that the interrelation of ozone cracking and flex cracking is a continuous source of some confusion since conditions for high-speed dynamic weathering exposure are also conditions conducive to flex cracking. Antioxidants which are effective in prolonging flex life may or may not show antiozonant activity. For instance, both / V- phenyl-2-naphthylamine and / V-isopropyl- / V-phenyl-p-phenylenediamine have antiflex-cracking activity, whereas only the latter is an antiozonant while the former is not (p. 1518 in J. C. AM- BELANG et al., Rubber Chemistry and Technology 36 (4), 1963, 1497-1591).

[0039] It is well known that aromatic amines can have undesirable toxicological properties, as many representatives of this class of chemicals are known to be harmful to human and animal health and aquatic life as well.

[0040] Especially, the continuous use of the well-established antiozonant class of PPDs is becoming more and more critical. The ECHA registration dossier states that “according to available information on degradation, all PPDs in question are not readily biodegradable and no significant biodegradation is observed but full abiotic degradation takes place”.

[0041] A possible explanation for the non-biodegradability is the hypothesis that 6PPD itself and possibly also 6PPD-quinone - one of its decomposition products - are highly toxic against bacteria. Even low concentrations may have a significant effect and kill bacteria or at least inhibit bacterial growth in the biodegradation tests on 6PPD. In the atmosphere rapid photodegradation takes place by reaction with photochemically produced OH radicals. According to the ECHA BASF SE 240613

[0042] 6 registration dossier, regarding environmental and monitoring data, 6PPD has been used as an indicator for other members of the PPD family as it is commonly used in tire production.

[0043] A recent study (Tian et al., Science 371 , 185-189 (2021) “A ubiquitous tire rubber-derived chemical induces acute mortality in coho salmon") found that in the U.S. Pacific Northwest, for coho salmon (Oncorhynchus kisutch), the stormwater exposure annually causes an unexplained acute mortality when adult salmon migrate to urban creeks to reproduce. A highly toxic quinone transformation product of / \ / -(1 ,3-dimethylbutyl)- / \ / '-phenyl-p-phenylenediamine (6PPD) was found. The retrospective analysis of representative roadway runoff and stormwater-affected creeks of the U.S. West Coast indicated widespread occurrence of 6PPD-quinone at toxic concentrations. Not only revealed those results unanticipated risks of 6PPD to some aquatic species, but it uncovered the toxicological relevance of dissipated tire rubber residues as well. These findings make clear that there is an existing need for identifying suitable alternative compounds to PPDs for their safe use as antiozonants in rubber products, including tires, which could help to reduce or even eliminate the quantity required of 6PPD and other PPDs. In addition, it is also preferable that those alternative solutions have a lower discoloration tendency than PPDs, which helps improving the acceptance by the customer and broadening the application range of such alternative solutions.

[0044] Durable long-lasting rubber products that retain their original color, remain safe and reliable throughout their service life but at the same time may reduce the release of environmentally toxic substances are presently still an unresolved requirement. Such needs are addressed by the rubber compositions products of the present invention.

[0045] SUMMARY OF THE INVENTION

[0046] It is an object of the invention to provide antidegradant, especially antiozonant compounds, which can be used in particular as antidegradants in vehicle tires or other technical rubber articles in order to achieve a protective effect for these articles and thereby substituting or reducing the presence of PPDs, especially of 6PPD.

[0047] The object is achieved by the use of N-heteroaromatic diaminoaryl compounds, more specifically N-heteroaromatic para-diaminoaryl compounds or derivatives as defined herein below, also referred to as “compound according to the (present) invention”.

[0048] Similar derivatives have been described as intermediate compounds for the preparation of therapeutically active histone deacetylase inhibitors (HDAC) in WO2014 / 181137, such as compound j) N5-(2-methoxyethyl)-N2-(5-methoxypyridin-2-yl)-N5-methylpyridine-2,5-diamine on page 21 , which is synthesized according to the general procedure Method B.

[0049] However, as said, none of these structurally similar compounds show the same substitution pattern as the compounds according to the present invention. BASF SE 240613

[0050] 7

[0051] Based on Quantitative Structure-Activity Relationship (QSAR) models, which - according to ECHA - are believed to provide plausible predictions on human health and environmental fate properties of compounds based on knowledge of their chemical structure, the compounds according to the invention used hereinafter as antioxidants and antiozonants according to the present invention are expected to be less harmful to the environmental and human and animal health, for instance suggesting a lower aquatic toxicity and lower skin sensitizing potential, as compared to the classic aromatic amines used for this purpose, such as, e.g., 6PPD or IPPD. Furthermore, the compounds according to the invention are obtained by the methods described further below. Additionally, their use as an antidegradant and / or antioxidant and / or antiozonant is claimed as well.

[0052] Another object of the invention is to provide a rubber composition comprising one or more N- heteroaromatic diaminoaryl derivative(s) as defined herein below.

[0053] Embodiments of the invention may be useful for finished rubber articles including nonpneumatic tires, solid tires, pneumatic tires, and tire components. Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0054] Particular embodiments of the present invention include rubber compositions, articles made from such rubber compositions, and the methods for making the same. Such embodiments include the tire product.

[0055] The tire product according to the invention comprises a rubber composition that is based upon a cross-linkable elastomer composition, such cross-linkable elastomer composition comprising for instance a highly unsaturated diene elastomer, a reinforcing filler, a vulcanization package and an antidegradant according to the present invention.

[0056] DETAILED DESCRIPTION OF THE INVENTION

[0057] The present invention relates to antidegradant or antiozonant compounds of formula (I)

[0058] Wherein

[0059] One of X1or X3is N and the other is a group CH, and

[0060] One of X2or X4is N and the other is a group CH, BASF SE 240613

[0061] 8 and

[0062] R1is selected from a group consisting of linear or branched Ci-Cw-alkyl, Cs-Cw-cycloal- kyl, or a CyCw-arylalkyl which is bonded to the respective nitrogen atom of formula (I) via a Ci-C4-alkyl radical;

[0063] R1’ is hydrogen

[0064] R2is selected from a group consisting of hydrogen, linear or branched Ci-Cw-alkyl, C3- Cw-cycloalkyl, OR3or NR4R5, and wherein

[0065] R3is selected from hydrogen, a linear or branched Ci-Cw-alkyl group or a

[0066] Cs-C -cycloalkyl group

[0067] R4, R5are both independently from one another selected either from hydrogen, a linear or branched Ci-Cw-alkyl group or a Cs-Cw-cycloalkyl group, or

[0068] R4and R5, together with the nitrogen atom they are bonded to, form a 5- to 9-membered saturated heterocyclic ring which may be unsubstituted or substituted with one or more Ci-C4-alkyls.

[0069] Individual embodiments and preferences of the antidegradant or antiozonant compounds of formula (I) are further outlined herein below.

[0070] In one embodiment of the present invention, X2and X3in the compound of formula (I) are both

[0071] N, and antiozonant compound is represented by the following structure of formula (1.1):

[0072] In another embodiment of the present invention, X1and X2in the antiozonant compound of formula (I) are both N and the antiozonant compound is represented by the following structure of formula (1.2):

[0073] In another embodiment of the present invention, X1and X4in the compound of formula (I) are both N, and the antiozonant compound is represented by the following structure of formula (1.3): BASF SE 240613

[0074] 9

[0075] In another embodiment of the present invention, X3and X4in the compound of formula (I) are both N and the antiozonant compound is represented by the following structure of formula (1.4):

[0076] The substituents R1and R2are defined as above for the derivate of formula (I).

[0077] The individual embodiments and preferences for R1and R2outlined below apply for the deri- vates of formula (I) as well as for its derivates with structures of formulae (1.1), (1.2), (1.3) and (I.4).

[0078] The Ci-C -alkyl group may be linear or branched and typically includes 1 to 10 carbon atoms, which means that any integer of 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 of the total number of carbon atoms falls under the definition of the alkyl. The alkyl group may be alternatively described using the formula CnH2n+i wherein n is 1 to 10, as described above. In various embodiments, the alkyl group may be described as methyl, ethyl, n-propyl, / -propyl, n-butyl, / -butyl, f-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, or any isomer thereof.

[0079] Same applies analogously for preferred Ci-Ce-alkyl or Ci-C4-alkyl groups.

[0080] The above said applies as well for all Ci-Cw-alkyl, Ci-Ce-alkyl or Ci-C4-alkyl groups defined for the substituents R1, R2, R3, R4and R5.

[0081] The Cs-C -cycloalkyl group corresponds analogously to a cyclic alkyl group, which includes 3 to 10 carbon atoms, which means that any integer of 3, 4, 5, 6, 7, 8, 9 or 10 of the total number of carbon atoms falls under the definition of the alkyl. In various embodiments, the cycloalkyl group may be described as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecanyl.

[0082] In one embodiment of the present invention R1in the derivate of formula (I) is selected from a group consisting of linear or branched Cs-Cs-alkyl, Cs-Cs-cycloalkyl, or a CyCw-arylalkyl which is bonded to the respective nitrogen atom of formula (I) via a Ci-C4-alkyl radical;

[0083] Preferably R1in the derivate of formula (I) is a Cs-Cs-alkyl bonded to the respective nitrogen atom via a secondary C-atom, a Cs-Cs-cycloalkyl or a CyCs-phenylalkyl which is bonded to the respective nitrogen atom via a Ci-C2-alkyl radical. BASF SE 240613

[0084] 10

[0085] In one embodiment of the present invention, R1in the derivate of formula (I) is more preferably selected from a group consisting of / -propyl, 1-methyl-propyl, 1-methyl-butyl, 1-ethyl-propyl, 1 ,2- dimethyl-propyl, 1 ,2-dimethyl-butyl, 1 ,3-dimethyl-butyl; 1 ,2,2-trimethyl-propyl, 1-ethyl-2-methyl- propyl, 1 -ethyl-butyl, 1-methyl-pentyl, 1 ,4-dimethyl-pentyl, 1-methyl-heptyl, 1-ethyl-hexyl, cyclohexyl and a-methylbenzyl.

[0086] In one embodiment of the present invention R1is most preferably / -propyl.

[0087] In another embodiment of the present invention R1is most preferably 1 ,3-dimethyl-butyl.

[0088] R2in the derivate of formula (I) is preferably selected from an electron-donating group, such as common electron-donating groups like alkyl (e.g., methyl, ethyl), alkoxy (e.g., methoxy, ethoxy), and amino (e.g., dimethylamino) substituents.

[0089] In one embodiment of the present invention R2in the derivate of formula (I) is preferably selected from a group consisting of hydrogen, linear or branched Ci-Cs-alkyl.

[0090] In one embodiment of the present invention R2in the derivate of formula (I) is more preferably selected from a group consisting of hydrogen, methyl, ethyl, n-propyl, / -propyl, n-butyl or f-butyl. In one embodiment of the present invention R2in the derivate of formula (I) is most preferably selected from an electron-donating group such as methyl, ethyl, n-propyl, / -propyl, n-butyl, / -butyl, f-butyl.

[0091] In another embodiment of the present invention R2in the derivate of formula (I) is preferably selected from an electron-donating group such as an alkoxy group OR3, wherein R3is hydrogen, a linear or branched Ci-C4-alkyl group or a Cs-Cs-cycloalkyl group.

[0092] In one embodiment R3of OR3is more preferably methyl.

[0093] In one embodiment R3of OR3is more preferably ethyl.

[0094] In another embodiment of the present invention R2in the derivate of formula (I) is preferably selected from an electron-donating group such as an amino group NR4R5, wherein R4and R5are both independently from one another selected either from hydrogen or a linear or branched Ci- Ce-alkyl or a Cs-Cs-cycloalkyl group.

[0095] In one embodiment, if R2is NR4R5, R4and R5are preferably selected independently from one another from hydrogen, methyl, / -propyl or 1 ,3-dimethyl-butyl.

[0096] In one embodiment, if R2is NR4R5, R4is preferably selected from methyl, / -propyl, or 1 ,3-dime- thyl-butyl and R5is preferably either hydrogen or methyl.

[0097] In one embodiment, if R2is NR4R5, R4and R5are preferably both methyl.

[0098] In one embodiment, if R2is NR4R5, R4is preferably methyl and R5is preferably hydrogen.

[0099] In one embodiment, if R2is NR4R5, R4is preferably / -propyl and R5is preferably hydrogen.

[0100] In one embodiment, if R2is NR4R5, R4is preferably 1 ,3-dimethyl-butyl and R5is preferably hydrogen. BASF SE 240613

[0101] 11

[0102] In another embodiment of the present invention R2in the derivate of formula (I) is preferably NR4R5, wherein R4and R5, together with the nitrogen atom they are bonded to, form a 5- to 9- membered saturated heterocyclic ring which may be unsubstituted or substituted with one or more Ci-C4-alkyls.

[0103] In one embodiment, if R2is NR4R5, R4and R5, together with the nitrogen atom they are bonded to, form preferably a 5- to 7-membered saturated heterocyclic ring which may be unsubstituted or substituted with one or more Ci-C4-alkyls.

[0104] In one embodiment, if R2is NR4R5, R4and R5, together with the nitrogen atom they are bonded to form preferably a 5- to 7-membered saturated unsubstituted heterocyclic ring.

[0105] In addition to the new compounds described above, compounds of formula (II), which encompasses the structures of compounds of formula (I), but allow for a broader substitution pattern on the non-linking amino group in para-position to the nitrogen atom linking the two (hetero-)aryl rings may as well be used as antidegradants and / or antioxidants and / or antiozonants.

[0106] Thus, one embodiment of the present invention are rubber compositions stabilized against effects of ozonation comprising antiozonant compounds of formula (II) wherein

[0107] X1, X2, X3, X4, X5, X6, X7and X8are each either N or the group CH, and wherein at maximum one of X1, X3, X5and X7is N and at maximum one of X2, X4, X6and X8is N; and

[0108] R1is selected from a group consisting of linear or branched Ci-C -alkyl, C3-C10- cycloalkyl, or a CyCw-arylalkyl which is bonded to the respective nitrogen atom of formula (I) via a Ci-C4-alkyl radical;

[0109] R1’ is selected from hydrogen or a group consisting of linear or branched C1-C10- alkyl, Cs-C -cycloalkyl, or a CyCw-arylalkyl which is bonded to the respective nitrogen atom of formula (I) via a Ci-C4-alkyl radical; BASF SE 240613

[0110] 12 and

[0111] R2is selected from a group consisting of hydrogen, linear or branched Ci-C -alkyl, Cs-C -cycloalkyl, OR3or NR4R5, and wherein

[0112] R3is selected from hydrogen, a linear or branched Ci-Cw-alkyl group or a Cs-Cw-cycloalkyl group

[0113] R4, R5are both independently from one another selected either from hydrogen, a linear or branched Ci-Cw-alkyl group or a Cs-C -cyclo- alkyl group, or

[0114] R4and R5, together with the nitrogen atom they are bonded to, form a 5- to 9-membered saturated heterocyclic ring which may be unsubstituted or substituted with one or more Ci-C4-alkyls.

[0115] The individual embodiments and preferences for R1and R2as outlined above for the derivates of formula (I) apply as well for derivates of formula (II).

[0116] The individual embodiments and preferences for R1’ of compounds of formula (II) are the same as those for R1in compounds of formula (I), including also hydrogen as one preferred embodiment.

[0117] The compounds of formula (II) as described hereinabove may also be added to the rubber formulation or be present in the rubber formulation in form of their respective quinone imines which are obtained via dehydrogenation of the parent heteroaromatic diaminoaryl compound:

[0118] For the use as antiozonants, structures of individual N-heteroaromatic diaminoaryl derivative compounds are exemplified hereinbelow.

[0119] Preferred are structures of formula (I.X1), wherein R1 , RT and R2 are defined according to one line in table B.1 below, wherein each line of table B.1 represents one exemplified individual embodiment of the antiozonant compounds according to the invention: formula (I. XI) BASF SE 240613

[0120] 13

[0121] Preferred are structures of formula (I.X2), wherein R1 , R and R2 are defined according to one line in table B.1 below, wherein each line of table B.1 represents one exemplified individual em- bodiment of the antiozonants compounds according to the invention: formula (I.X2)

[0122] Preferred are structures of formula (I.X3), wherein R1, RT and R2 are defined according to one line in table B.1 below, wherein each line of table B.1 represents one exemplified individual em- bodiment of the antiozonant compounds according to the invention: formula (I.X3)

[0123] Preferred are structures of formula (I.X4), wherein R1, RT and R2 are defined according to one line in table B.1 below, wherein each line of table B.1 represents one exemplified individual em- bodiment of the antiozonants compounds according to the invention:

[0124] Table B.1: preferred definitions of substituents for exemplified structures above BASF SE 240613

[0125] 14 BASF SE 240613

[0126] 15 BASF SE 240613

[0127] 16 BASF SE 240613

[0128] 17

[0129] The object of the present invention is achieved by the use of N-heteroaromatic diaminoaryl derivatives as defined herein above, which are particularly suitable as an antidegradant and / or antiozonant in vehicle tires.

[0130] They also can be used for producing other technical rubber articles, such as rubber bands, (conveyor) belts, hoses, cables, automotive mounts, bushings, air springs, bellows, profiles, seals, membranes, tactile sensors for medical applications or robots, as well as, e.g., shoe soles or parts thereof.

[0131] In the case of vehicle tires or other technical rubber articles, the N-heteroaromatic diaminoaryl derivative compounds of formula (I) or (II) are used in particular in a rubber composition.

[0132] A further subject matter of the invention is thus, as already mentioned, a rubber composition.

[0133] The rubber composition according to the invention contains the N-heteroaromatic diaminoaryl derivative compound according to formula (I) or (II). The rubber composition according to the invention can in principle be any rubber composition in which the novel use of the N-heteroaro- matic diaminoaryl derivative compound of the formula (I) or (II) according to the invention achieves improved properties, in particular increased longevity by aging protection and / or ozone protection.

[0134] The rubber composition according to the invention contains at least one rubber.

[0135] The rubber composition according to the invention preferably contains 0.1 to 10 phr (parts per hundred), particularly preferably 0.2 to 5 phr, very particularly preferably 0.3 to 3 phr, of the compound according to formula (I) or (II).

[0136] The term phr (parts per hundred parts of rubber by weight) used in this specification is the quantity specification customary in the rubber industry for rubber composition, like rubber mixture formulations. The dosage of the parts by weight of the individual substances is referred to in this BASF SE 240613

[0137] 18 document to 100 parts by weight of the total mass of all high molecular weight rubber elastomers (Mw greater than 20,000 g / mol) present in the mixture.

[0138] Further components of the rubber compositions according to the present invention are described hereinbelow.

[0139] Rubber elastomers suitable for use with particular embodiments of the present invention include highly unsaturated diene elastomers. According to advantageous embodiments of the invention, the rubber composition according to the present invention contains at least one diene rubber. In a further embodiment the rubber composition contains a diene rubber or a mixture of two or more different diene rubbers.

[0140] Diene rubbers are rubbers which are produced by polymerization or copolymerization of dienes and / or cycloalkenes and thus either have C = C double bonds in the main chain or in the side groups.

[0141] Diene rubbers are preferably selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), epoxidized polyisoprene (ENR), (poly)butadiene rubber (BR), buta- diene-isoprene rubber, styrene-butadiene rubber (SBR), solution-polymerized styrene-butadi- ene rubber (SSBR), emulsion-polymerized styrene-butadiene rubber (ESBR), styrene-isoprene rubber, isobutylene isoprene rubber (HR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers, liquid rubbers having a molecular weight Mw of greater than 20,000 g / mol, polynorborneneisoprene-isobutylene copolymer, acrylate rubber, fluorine rubber, silicone rubber, polysulfide rubber, epichlorohydrin rubber, styrene-isoprene-butadiene terpolymer, and hydrogenated styrene-butadiene rubber.

[0142] Nitrile rubber, hydrogenated acrylonitrile butadiene rubber, chloroprene rubber, butyl rubber, ha- lobutyl rubber and / or ethylene-propylene-diene rubber (EPDM), which are often used in the production of technical rubber articles, such as belts and hoses, and / or shoe soles, may optionally be used as well with regard to the present invention.

[0143] The natural and / or synthetic polyisoprene of all embodiments can be both cis- 1 ,4-polyisoprene and 3,4-polyisoprene and copolymers thereof.

[0144] The polyisoprenes include synthetic cis-1 ,4 polyisoprene, which may be characterized as possessing cis-1 ,4 bonds at more than 90 mol.% or alternatively, at more than 98 mol.%.

[0145] Natural rubber (NR) is such a cis-1 ,4 polyisoprene, in which the cis-1 , 4-component in the natural rubber is greater than 99% by weight. Furthermore, a mixture of one or more natural polyiso- prene(s) with one or more synthetic polyisoprene(s) is also conceivable.

[0146] Within the scope of the present invention, the term "natural rubber" is to be understood as naturally occurring rubber which can be obtained from Hevea rubber trees and "non-Hevea" BASF SE 240613

[0147] 19 sources. Non-Hevea sources are, for example, Guayule shrubs and soldering teeth such as, for example, TKS (Taraxacum kok-saghyz; Russian Dandelion).

[0148] If butadiene rubber (= BR, polybutadiene) is contained in the rubber composition according to the invention, it can be all types known to the person skilled in the art. These include, inter alia, the so-called high-cis and low-cis types, where polybutadiene having a cis content is greater than or equal to 90% by wt. % as a high-cis type and polybutadiene having a cis content of less than 90% by wt. % is referred to as the low-cis type. A low-cis polybutadiene is, for example, Li- BR (lithium-catalyzed butadiene rubber) with a cis content of 20 to 50 wt. %. With a high-cis BR, particularly good properties and a low hysteresis of the rubber composition are achieved.

[0149] The polybutadienes or polybutadienes used may be end-group-modified with modifications and functionalizations and / or functionalized along the polymer chains. The modification can be those having hydroxy groups and / or ethoxy groups and / or epoxy groups and / or siloxane groups and / or amino groups and / or aminosiloxane and / or carboxy groups and / or phthalocyanine groups and / or silane groups and / or sulfide groups. Other modifications known, also referred to as functionalizations, are also possible. Constituent of such functionalizations may be metal atoms.

[0150] For the case where at least one styrene-butadiene rubber (styrene-butadiene copolymer) is contained in the rubber composition, it can be both solution-polymerized styrene-butadiene rubber (SSBR) and emulsion-polymerized styrene-butadiene rubber (ESBR), wherein also a mixture of at least one SSBR and at least one ESBR can be used. The terms "styrene-butadiene rubber" and "styrene-butadiene copolymer" are used synonymously in the context of the present invention.

[0151] The styrene-butadiene copolymer used can be end-group-modified and / or functionalized along the polymer chains with the modifications and functionalizations mentioned above for the polybutadiene.

[0152] In one embodiment, at least one diene rubber is selected from the group consisting of natural polyisoprene (NR, natural rubber), synthetic polyisoprene (IR), butadiene rubber (BR), solution polymerized styrene-butadiene rubber (SSBR), emulsion polymerized styrene-butadiene rubber (ESBR), butyl rubber (HR), and halobutyl rubber.

[0153] According to a particular embodiment of the invention, the at least one diene rubber is selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene BASF SE 240613

[0154] 20 rubber (BR), solution-polymerized styrene-butadiene rubber (SSBR) and emulsion-polymerized styrene-butadiene rubber (ESBR).

[0155] According to a particular embodiment of the invention, the rubber composition contains at least one natural polyisoprene (NR), for instance in amounts of 5 to 55 phr, and according to a particular embodiment of the invention 5 to 25 phr, very particularly 5 to 20 phr. Such a rubber composition exhibits good processability and reversion stability and optimized tearing properties and optimum rolling resistance behavior.

[0156] According to a particular embodiment of the invention, the rubber composition contains at least one polybutadiene (BR, butadiene rubber), for instance in amounts of 10 to 80 phr, particularly 10 to 50 phr, and according to a particular embodiment of the invention 15 to 40 phr. In this way, particularly good friction and abrasion properties of the rubber composition according to the invention and an optimum braking behavior are achieved.

[0157] According to a particular embodiment of the invention, the rubber composition contains at least one solution-polymerized or emulsion-polymerized styrene-butadiene rubber (SSBR or ESBR), for instance in amounts of 10 to 80 phr, particularly 30 to 80 phr, and according to a particular embodiment of the invention 50 to 70 phr. Particularly good rolling resistance properties of the rubber composition according to the invention are hereby achieved. According to particularly advantageous embodiments of the invention, SSBR and ESBR are used in combination with at least one further rubber in order to achieve an optimal and balanced property profile.

[0158] Also suitable for use in particular embodiments of the present invention are rubber elastomers that are copolymers and include, for example, butadiene-styrene copolymers (SBR), butadieneisoprene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-butadiene-styrene copolymers (SBIR) and mixtures thereof.

[0159] The elastomer system can be a blend of various elastomers with a total of 100 phr.

[0160] In view of the above, the rubber compositions according to the present invention may be mixtures of rubbers of different origins.

[0161] In a particular embodiment the rubber compositions according to the present invention include a mixture of one or more natural and one or more synthetic rubbers.

[0162] However, the rubber compositions according to the present invention may include as well only synthetic rubber(s).

[0163] Further, the rubber compositions according to the present invention may also include only natural rubber(s). BASF SE 240613

[0164] 21

[0165] The rubber composition preferably contains at least one filler, for instance in amounts of 30 to 500 phr, particularly 50 to 400 phr, optionally 80 to 300 phr.

[0166] Reinforcing fillers used in the rubber composition according to the present invention include carbon black and / or silica (and associated silane chemistry).

[0167] Carbon black, which is an organic filler, is well known in the rubber compounding field.

[0168] The rubber composition according to the present invention contains 30 to 300 phr, particularly 30 to 200 phr, more particularly 40 to 100 phr of at least one carbon black. In these amounts, carbon black is contained as sole filler or as a main filler. If carbon black is merely present as a further filler in addition to a main filler, such as, in particular, silica (see herein below), the rubber composition according to the present invention contains 0.1 to 60 phr, particularly 3 to 40 phr, especially 5 to 30 phr of at least one carbon black.

[0169] Suitable carbon blacks are any carbon blacks known in the art and suitable for the given purpose for example, any carbon black having a BET surface area or a specific CTAB surface area both of which are less than 400 m2 / g or alternatively, between 20 and 200 m2 / g may be suitable for particular embodiments based on the desired properties of the cured rubber composition. The CTAB specific surface area is the external surface area determined in accordance with Standard AFNOR-NFT-45007 of November 1987. Suitable carbon blacks of the type HAF, ISAF and SAF, for example, are conventionally used in tire treads. Non-limitative examples of carbon blacks include, for example, the N 115, N134, N234, N299, N326, N330, N339, N343, N347, N375 and the 600 series of carbon blacks, including, but not limited to N630, N650 and N660 carbon blacks.

[0170] Silica may also be useful as reinforcement filler. The silica may be any known reinforcing silica for example, any precipitated or pyrogenic silica having a BET surface area and a specific CTAB surface area both of which are less than 450 m2 / g or alternatively, between 20 and 400 m2 / g may be suitable for particular embodiments based on the desired properties of the cured rubber composition.

[0171] Particular embodiments of rubber compositions disclosed herein may include a silica having a CTAB of between 80 and 200 m2 / g, between 100 and 190 m2 / g, between 120 and 190 m2 / g or between 140 and 180 m2 / g.

[0172] Such silicas lead, for example, to rubber compositions for tire treads having particularly good physical properties. In addition, advantages in mixing processing can result from a reduction in the mixing time with constant product properties, which result in improved productivity. Commercially available examples of such silicas are Ultrasil ® VN3 type (trade name) from Evonik and Zeosil ® 1165 MP from Solvay.

[0173] According to particular embodiments of the invention, the rubber composition contains silicic acid as filler, for instance in amounts of 30 to 500 phr, particularly 50 to 400 phr, more particularly 80 to 300 phr. In these amounts, silicic acid is used in particular as sole filler or as a main filler (more than 50% by weight based on the total amount of filler). BASF SE 240613

[0174] 22

[0175] According to a further embodiment of the invention, the rubber composition contains at least one silicic acid as a further filler, in addition to another main filler, such as in particular a carbon black. Under these circumstances it is used in amounts of 5 to 100 phr, particularly 5 to 80 phr, more particularly 10 to 60 phr.

[0176] According to a particular embodiment of the invention, the rubber composition contains 5 to 60 phr, particularly preferably 5 to 40 phr, of at least one carbon black and 50 to 300 phr, preferably 80 to 200 phr of at least one silica.

[0177] When silica is added to the rubber composition, a proportional amount of a silane coupling agent is also added to the rubber composition. The silane coupling agent is a sulfur- containing organosilicon compound that reacts with the silanol groups of the silica during mixing and with the elastomers during vulcanization to provide improved properties of the cured rubber composition. A suitable coupling agent is one that is capable of establishing a sufficient chemical and / or physical bond between the inorganic filler and the diene elastomer, which is therefore at least bifunctional, meaning which is capable of bonding physically and / or chemically with the inorganic filler. One bond may be established, for example, between a silicon atom of the coupling agent and the surface hydroxyl (OH) groups of the inorganic filler (for example, surface silanols in the case of silica), and the other bond may then be established (physically and / or chemically) with the diene elastomer, for example by means of a sulfur atom. Hence, the silane coupling agents react with the surface silanol groups of the silicic acid or other polar groups during the mixing of the rubber or rubber composition (in situ) or even before the addition of the filler to the rubber in the sense of a pretreatment (pre-modification).

[0178] Silane coupling agents used according to the present invention can be all types known, and one or more different silane coupling agents can be used in combination with one another. The rubber composition can thus contain a mixture of different silanes.

[0179] Coupling agents known from the prior art are bifunctional organosilanes which have at least one alkoxy, cycloalkoxy or phenoxy group as a leaving group on the silicon atom and which, as other functionality, have a group which, if appropriate after cleavage, can undergo a chemical reaction with the double bonds of the polymer. The last-mentioned group can be, for example, the following chemical groups: — SCN, — SH, — NH2 or — Sx— (where x = 2 to 8).

[0180] Thus, for example, 3-mercaptopropyltriethoxy silane can be used as silane coupling agents, 3- thiocyanato-propyltrimethoxysilane or 3,3 '-bis (triethoxysilylpropyl) polysulfides having 2 to 8 sulfur atoms, such as, for example, 3,3 '-bis (triethoxysilylpropyl) tetrasulfide (TESPT), the corresponding disulfide (TESPD) or other mixtures of the sulfides having 1 to 8 sulfur atoms with different contents of the various sulfides. TESPT can also be added, for example, as a mixture with industrial carbon black (e.g. X50S® from Evonik). Suitable silanes are described in WO 2008 / 083241 A1 , WO 2008 / 083242 A1 , WO 2008 / 083243 A1 and WO 2008 / 083244 A1. BASF SE 240613

[0181] 23

[0182] Blocked mercaptosilanes, e.g. as known from WO 99 / 09036, can also be used as silane coupling agents. Commercially available silanes are sold under the name NXT™ Silane by Mo- mentive, or under the name of VP Si 363® by Evonik Industries.

[0183] Further optionally reinforcing fillers are, for example, carbon nanotubes (CNT) including discrete CNTs, so-called hollow carbon fibers (HCF) and modified CNT containing one or more functional groups, such as hydroxy, carboxyl and carbonyl groups), zeolite, graphite and graphenes, and so-called "carbon-silica dual-phase".

[0184] Conventional non-reinforcing fillers such as clays, bentonite, talc, chalk, kaolin, aluminosilicate, starch, magnesium oxide, titanium dioxide may be present as well. In the context of the present invention, further non-reinforcing fillers include also rubber gels and fibers (such as, for example, aramid fibers, glass fibers, carbon fibers, cellulose fibers).

[0185] Plasticizers, which may as well be present, include oils and resins (from petroleum or other natural renewable resources, e.g., sunflower seeds, citrus orange peels). Processing oils are generally extracted from petroleum and are classified as being paraffinic, aromatic or naphthenic type processing oil, including MES and TDAE oils. Processing oils may also include, inter alia, plant-based oils, such as sunflower oil, rapeseed oil and vegetable oil. Some of the rubber compositions disclosed herein may include an elastomer, such as a styrene-butadiene rubber, that has been extended with one or more such processing oils but such oil is limited in the rubber composition of particular embodiments as being no more than 40 phr of the total elastomer content of the rubber composition.

[0186] The rubber composition according to the invention is preferably used in a vulcanized state, in particular in vehicle tires or other vulcanized technical rubber articles.

[0187] The terms "vulcanized" and "crosslinked" are used synonymously in the context of the present invention.

[0188] The vulcanization of the rubber composition according to the present invention is preferably carried out in the presence of sulfur and / or sulfur with the aid of vulcanization accelerators, wherein some vulcanization accelerators can simultaneously act as sulfur donors.

[0189] The accelerator may be selected from the group of thiazole accelerators and / or mercapto accelerators and / or sulfenamide accelerators and / or thiocarbamato accelerators and / or thiuram accelerators and / or thiophosphate accelerators and / or thiourea accelerators and / or xanthate accelerators and / or guanidine accelerators. Other known vulcanization agents may be used as well, as for example, peroxide and ionic crosslinking agents. Vulcanization agents as used herein are those materials that cause the cross-linkage of the rubber and therefore may be BASF SE 240613

[0190] 24 added only to the productive mix so that premature curing does not occur, such agents are for example elemental sulfur or sulfur donating agents, as well as peroxides.

[0191] The vulcanization system used may especially be based on sulfur and on an accelerator. Use may be made of any compound capable of acting as an accelerator of the vulcanization of elastomers in the presence of sulfur, in particular those chosen from the group of sulfenamide accelerators comprising for instance benzothiazyl-2-sulphenyl morpholide (MBS), 2-mercaptobenzo- thiazyl disulfide (abbreviated to "MBTS"), N-cyclohexyl-2- benzothiazolesulphenamide (abbreviated to "CBS"), N,N-dicyclohexyl-2- benzothiazolesulphenamide (abbreviated to "DCBS”), N- tert-butyl-2- benzothiazolesulphenamide (abbreviated to "TBBS"), N-tert-butyl-2-benzothiazole- sulphenimide (abbreviated to "TBSI ") and the mixtures of these compounds.

[0192] A primary accelerator of the sulfenamide type may be used as one embodiment of the present invention.

[0193] The rubber composition may also include vulcanization retarders, a vulcanization system based, for example, on sulfur or on a peroxide, vulcanization accelerators, vulcanization activators, and so forth.

[0194] If the rubber composition contains a sulfur-donating substance, it is preferably selected from the group containing, for example, thiuram disulfides, such as, for example, tetrabenzylthiuram disulfide (TBzTD) and / or tetramethylthiuram disulfide (TMTD) and / or tetraethylthiuram disulfide (TETA), and / or thiuram tetrasulfides, such as, for example, dipentamethylenthiuramtetrasulfide (DPTT), and / or dithiophosphates, such as, for example, Didis (bis-(diisopropyl)thiophosphoryl disulfide) and / or bis (O,O-2-ethylhexyl thiophosphoryl) polysulfide (e.g. Rhenocure SDT 50®, Rheinchemie GMBH) and / or zinc dichloroyldithiophosphate (e.g. Rhenocure ZDT / S ®, Rhein- chemie GMBH) and / or zinc alkyldithiophosphate, and / or I, 6-bis (N, N-dibenzylthiocar- bamoyldithio) hexane and / or diaryl polysulfides and / or dialkyl polysulfides.

[0195] Other network-forming systems, such as those obtainable, for example, under the trade names Vulkuren®, Duralink® or Perkalink®, or network-forming systems, as described in WO 2010 / 049216 A2, can also be used in the rubber composition according to the present invention.

[0196] The vulcanization system may further include various known secondary accelerators or vulcanization activators, such as zinc oxide or zinc complexes such as zinc ethylhexanoate, fatty acids (e.g. stearic acid) and guanidine derivatives (in particular diphenylguanidine, or “DPG”). Particular preference is given to the use of the accelerators TBBS and / or CBS and / or diphenylguanidine (DPG).

[0197] The proportion of the total amount of these additives is for instance 3 to 150 phr, particularly 3 to 100 phr and very particularly 5 to 80 phr.

[0198] As a further additive, zinc oxide (ZnO) can be present within the abovementioned amounts. These may be all types of zinc oxide known to the person skilled in the art, such as, for example, ZnO granules or powders. The conventionally used zinc oxide generally has a BET surface BASF SE 240613

[0199] 25 area of less than 10 m2 / g. However, it is also possible to use a zinc oxide having a BET surface area of 10 to 100 m2 / g, such as, for example, so-called "nano-zinc oxides".

[0200] Furthermore, in addition to the above, the rubber composition according to the present invention may contain customary additives in customary parts by weight, which are preferably added during their preparation in at least one basic mixing stage.

[0201] Such optional general additives include:

[0202] • agents for the binding of fillers, in particular carbon black or silicic acid, such as, for example, S-(3-aminopropyl)thiosulfuric acid and / or metal salts thereof binding to carbon black (silane coupling agents, binding to silica, have been described herein above);

[0203] • ozone protection waxes;

[0204] • resins, in particular adhesive resins for inner tire components;

[0205] • mastication aids, such as, for example, 2,2'-dibenzamidodiphenyl disulfide (DBD);

[0206] • process auxiliaries, such as, in particular, fatty acid esters and metal soaps, such as, for example, zinc soaps and / or calcium soaps;

[0207] According to particularly advantageous embodiments, the rubber composition according to the invention contains, in addition to the compounds of formula (I) or (II) according to the invention, no further antidegradants from the group of p-phenylenediamines.

[0208] In particular, according to one embodiment, the rubber composition according to the invention may contain 0 to 1 phr of further ageing inhibitors based on diamines which are selected from the group containing consisting of / V-phenyl- / V'-(1 ,3-dimethylbutyl)-p-phenylenediamine (6PPD), / V, / V'-diphenyl-p-phenylenediamine (DPPD), / V, / V'-ditolyl-p-phenylenediamine (DTPD), / V-isopro- pyl- / V'-phenyl-p-phenylenediamine (IPPD), A / -(l 1 ,4-dimethylpentyl)- / \ / -phenyl-p-phenylenedia- mine (7PPD).

[0209] With the preferably very small amounts of the mentioned diamines and the compound according to the invention according to formula (I) or (II), it is still possible to achieve a good protective effect. In such case, the compound of the formula (I) or (II) according to the invention replaces the mentioned diamines known in the prior art.

[0210] According to a further embodiment of the invention, at least one further one of said diamine ageing inhibitors may also be present, so that the compound according to the invention partially replaces the diamines known in the prior art, which allow for conventional results without losses. BASF SE 240613

[0211] 26

[0212] According to another embodiment, ageing inhibitors based on dihydroquinoline, such as TMQ, may be present in the rubber composition in addition to the compound of formula (I) or (II) according to the present invention. The amount of dihydroquinolines present, such as in particular TMQ, is for instance 0.1 to 5 phr, in particular 0.5 to 2.5 phr.

[0213] A further subject matter of the present invention is a vehicle tire which comprising the rubber composition according to the present invention containing at least one compound of formula (I) or (II) as defined herein above.

[0214] The vulcanized vehicle tire has, at least in one component, a vulcanizate of at least one rubber composition according to the invention. It is known to a person skilled in the art that most substances, such as, for example, the rubbers contained, are present in chemically modified form either after mixing or only after vulcanization.

[0215] In the context of the present invention, vehicle tires are understood to be pneumatic vehicle tires and solid rubber tires, including tires for industrial and construction site vehicles, trucks, passenger cars and two-wheel tires.

[0216] The vehicle tire according to the invention preferably has the rubber composition according to the invention in at least one outer component, wherein the outer component is preferably a tread, a side wall and / or a horn profile.

[0217] The vehicle tire according to the invention can thus comprise the rubber composition according to the present invention containing one or more compound(s) of formula (I) or (II) and a plurality of further components as described hereinabove in an optionally adapted composition.

[0218] Methods of production and use of the present invention are described in the following:

[0219] The rubber compositions that are embodiments of the present invention may be produced in suitable mixers in a manner known to those having ordinary skill in the art. Typically, the mixing may occur using two successive preparation phases, a first phase of thermo-mechanical working at high temperature followed by a second phase of mechanical working at a lower temperature.

[0220] The first phase, sometimes referred to as a "non-productive" phase, includes thoroughly mixing, typically by kneading, the various ingredients of the composition but excluding some components of the vulcanization system such as the vulcanization agents, the accelerators, and the retarders. This first phase is carried out in a suitable kneading device, such as an internal mixer of the Banbury type, until under the action of the mechanical working and the high shearing BASF SE 240613

[0221] 27 imposed on the mixture, a maximum temperature of generally between 120°C and 190°C is reached, indicating that the components are well dispersed.

[0222] After cooling the mixture, a second phase of mechanical working is implemented at a lower temperature. Sometimes referred to a "productive" phase, this finishing phase consists of incorporating some components of the aforementioned vulcanization system that were not added in the “non-productive” phase, including the vulcanization agents, the accelerators, and the retarders into the rubber composition using a suitable device, such as an open mill. It is performed for an appropriate time (typically, for example, between 1 and 30 minutes or between 2 and 10 minutes), and at a sufficiently low temperature, i.e. , lower than the vulcanization temperature of the mixture, so as to protect against premature vulcanization.

[0223] Thus the rubber composition according to the present invention can be formed into useful articles, including tire components. Tire treads, for example, may be formed as tread bands and then later made a part of a tire or they may be formed directly onto a tire carcass by, for example, extrusion and then cured in a mold. Other components such as those located in the bead area of the tire or in the sidewall may be formed and assembled into a green tire and then cured with the curing of the tire.

[0224] According to a preferred development of the invention, a plurality of accelerators is added in the final mixing stage in the production of the sulfur-crosslinkable rubber composition.

[0225] The sulfur-crosslinkable rubber composition according to the invention is prepared by the process customary in the rubber industry, in which a basic mixture with all constituents other than the vulcanization system (sulfur and vulcanization-influencing substances) is initially produced in one or more mixing stages. The finished mixture is produced by adding the vulcanization system in a last mixing stage. The finished mixture is, for example, further processed by an extrusion process or calendering and brought into the corresponding form.

[0226] The further processing is then carried out by vulcanization, wherein a sulfur crosslinking takes place on the basis of the vulcanization system added in the context of the present invention. The rubber composition according to the invention described above is particularly suitable for use in vehicle tires, in particular pneumatic vehicle tires.

[0227] For use in vehicle tires, the mixture is preferably introduced as a finished mixture before vulcanization into the form of a tread and applied as is known during the production of the vehicle tire blank.

[0228] The rubber composition according to the invention for use as a side wall 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 forms of the still unvulcanized rubber composition for one or more different body mixtures then serve for the construction of a green tire. BASF SE 240613

[0229] 28

[0230] In this context, the rubber compositions for the inner components of a tire are referred to as the body mixture, such as substantially inner core (inner layer), core profile, belt, shoulder, belt profile, carcass, bead amplifier, bead profile, horn profile and bandage. The still unvulcanized tire blank is then vulcanized.

[0231] For the use of the rubber composition according to the invention in other rubber articles such as belts, in particular in conveyor belts, the extruded or unvulcanized mixture is brought into the corresponding form and is often provided with strength carriers, for example synthetic fibers or steel cords. In most cases, this results in a multi-layer structure consisting of one and / or more layers of rubber composition, one and / or more layers of the same and / or different strength members and one and / or more further layers or the like and / or another rubber composition.

[0232] Consequently, in view of the above, the present invention relates as well to the use of the compound according to formula (I) or (II) as an antidegradant and / or antiozonant in vehicle tires and / or technical rubber articles, for instance rubber articles like an air spring, a bellow, a conveyor belt, a hose, a rubber band, a profile, a seal, a membrane, tactile sensors for medical applications or robot applications or a shoe sole or parts thereof.

[0233] EXAMPLES

[0234] The invention is further illustrated by the following examples, which are to be regarded only as illustrations and not delimitative of the invention in any way. The characterization of the innovative antiozonant molecules and the properties of the rubber compositions disclosed in the examples were evaluated as described below.

[0235] S. Synthesis Examples

[0236] S.1. Synthesis of 6-chloro- / V-(4-methylpentan-2-yl)pyridin-3-amine (Intermediate IC.1)

[0237] 5-amino-2-chloropyridine (12.8 g, 100 mmol, 1.0 equiv) and methyl isobutyl ketone (20.0 g, 200 mmol, 2.0 equiv) were dissolved in methanol (300 mL). Acetic acid (18.0 g, 300 mmol, 3.0 equiv) was added and the mixture was stirred at room temperature for 10 minutes. Sodium cya- noborohydride (9.41 g, 150 mmol, 1.5 equiv) was added and the mixture was heated to reflux for 5 hours. HPLC control did show 55% product, additional sodium cyanoborohydride (6 g, 95 mmol, 0.95 equiv) was added and the mixture was stirred at reflux overnight. The reaction mixture was poured into ammonia solution and extracted with ethyl acetate thrice. The combined BASF SE 240613

[0238] 29 organic layers were washed with brine, the organic layer was dried (Na2SO4) and the solvent was removed in vacuo. The crude product was purified by column chromatography (silica, cyclohexane I ethyl acetate gradient) which gave access to Intermediate IC.1 (14.2 g, 66.8 mmol, 67% yield) as a pale-yellow sticky oil.

[0239] 1H-NMR (400 MHz, CDCI3) 6 = 0.91 (d, J = 6.6 Hz, 3H), 0.94 (d, J = 6.6 Hz, 3H), 1.16 (d, J = 5.4 Hz, 3H), 1 .24 - 1 .33 (m, 1 H), 1.40 - 1.52 (m, 1 H), 1.67 - 1.82 (m, 1 H), 3.42 - 3.55 (m, 2H), 6.83 (dd, J = 8.6, 3.1 Hz, 1 H), 7.00 - 7.12 (m, 1 H), 7.73 (d, J = 2.9 Hz, 1 H).

[0240] S.2. Synthesis of / V5-(4-methylpentan-2-yl)- / \ / 2-(pyridin-2-yl)pyridine-2,5-diamine (Inventive Compound C.1) .

[0241] Under argon BippyPhos [= 5-(di-ferf-butylphosphaneyl)-T,3',5'-triphenyl-T / 7-1 ,4'-bipyrazole] (1.05 g, 2.07 mmol, 0.04 equiv) and Pd2(dba)s [= tris(dibenzylideneacetone)dipalladium(0)] (0.47 g, 0.52 mmol, 0.01 equiv) were dissolved in 2-methyl-2-butanol (180 mL). Powdered potassium hydroxide (4.35 g, 77.6 mmol, 1.5 equiv) and water (1.8 mL) were added. The mixture was stirred at room temperature for 20 minutes. Subsequently, Intermediate IC.1 (11.0 g, 51.7 mmol, 1.0 equiv) and 2-aminopyridine (5.35 g, 56.9 mmol, 1.1 equiv) were added. The mixture was stirred at 90°C inner temperature overnight. The reaction mixture was filtered over silica after dilution with ethyl acetate. The organic layer was washed with water and the aqueous layer was extracted with ethyl acetate thrice. The combined organic layers were dried (Na2SO4) and the solvent was removed in vacuo. The crude product was purified by column chromatography (silica, cyclohexane I ethyl acetate gradient) which gave access to / \ / 5-(4-methylpentan-2-yl)- / \ / 2- (pyridin-2-yl)pyridine-2,5-diamine (9.00 g, 33.3 mmol, 64% yield) as a pale green solid.

[0242] 1H-NMR (400 MHz, CDCI3) 6 = 0.87 (d, J = 6.6 Hz, 3H), 0.91 (d, J = 6.6 Hz, 3H), 1.07 (d, J = 6.2 Hz, 3H), 1.21 (dt, J = 13.6, 6.9 Hz, 1 H), 1.43 (dt, J = 13.9, 7.0 Hz, 1 H), 1.73 (dp, J = 13.8, 7.1 Hz, 1 H), 3.37 - 3.47 (m, 1 H), 4.95 - 5.04 (m, 1 H), 6.70 (ddd, J = 6.9, 5.0, 1 .0 Hz, 1 H), 6.98 (dd, J = 8.9, 3.0 Hz, 1 H), 7.44 (d, J = 8.5 Hz, 1 H), 7.48 - 7.56 (m, 2H), 7.63 (d, J = 2.8 Hz, 1 H), 8.06 - 8.13 (m, 1 H), 9.06 (s, 1 H). BASF SE 240613

[0243] 30

[0244] S.3. Synthesis of / V2-(5-methoxypyridin-2-yl)- / \ / 5-(4-methylpentan-2-yl)pyridine-2,5-diamine

[0245] (Inventive Compound C.2)

[0246] Following the synthesis procedure of Synthesis Example S.2, using Intermediate IC.1 and 2- amino-5-methoxypyridine gave access to C.2 (2.1 g, 9.4 mmol, 74% yield) as a dark brown oil.

[0247] 1H-NMR (400 MHz, CDCI3) 5 = 0.91 (d, J = Q.Q Hz, 3H), 0.94 (d, J=Q.Q Hz, 3H), 1.15 (d, J = Q.2 Hz, 3H), 1.25 (dt, J= 13.7, 6.9 Hz, 1H), 1.47 (dt, J= 13.9, 7.1 Hz, 1H), 1.76 (dp, J= 13.4, 6.7 Hz, 1 H), 2.93 - 3.24 (m, 1 H), 3.45 (h, J = 6.4 Hz, 1 H), 3.81 (s, 3H), z6.94 (dd, J = 8.8, 2.9 Hz, 1H), 7.12 (s, 1H), 7.18 (dd, J= 9.0, 3.0 Hz, 1H), 7.29 (d, J= 8.8 Hz, 1H), 7.33 (d, J= 9.0 Hz, 1 H), 7.70 (d, J = 2.8 Hz, 1 H), 7.92 (d, J = 3.0 Hz, 1 H).

[0248] S.4. Synthesis of 5-chloro- / V-(4-methylpentan-2-yl)pyridin-2-amine (Intermediate IC.2)

[0249] According to the procedure provided in Synthesis Example S.1, using 2-amino-5-chloropyridine (12.9 g, 100 mmol, 1.0 equiv) gave access to Intermediate IC.2 (3.8 g, 17.9 mmol, 18% yield).

[0250] 1H-NMR (400 MHz, CDCI3) 5 = 0.90 (d, J = Q.Q Hz, 3H), 0.93 (d, J=Q.Q Hz, 3H), 1.17 (d, J = 6.3 Hz, 3H), 1.30 (ddd, J= 13.8, 7.5, 6.4 Hz, 1H), 1.39-1.47 (m, 1H), 1.64-1.79 (m, 2H), 3.69- 3.84 (m, 1H), 4.30 (m, 1H), 6.29 (d, J= 8.7 Hz, 1H), 7.33 (dd, J= 8.9, 2.6 Hz, 1H).

[0251] S.5. Synthesis of / V5-(4-methoxyphenyl)- / \ / 2-(4-methylpentan-2-yl)pyridine-2,5-diamine (Compar- ative Compound CC.4) BASF SE 240613

[0252] 31

[0253] Compound C.3 was synthesized according to the procedure provided in Synthesis Example S.2 using Intermediate IC.2 (3.8 g, 17.9 mmol, 1.0 equiv) and p-anisidine (2.42 g, 19.7 mmol, 1.1 equiv.) giving access to C.3 (3.8 g, 12.8 mmol, 72% yield) as dark brown oil.

[0254] 1H-NMR (400 MHz, CDCI3) 5 = 0.92 (d, J = Q.Q Hz, 3H), 0.94 (d, J=Q.7 Hz, 3H), 1.18 (d, J = 6.3 Hz, 3H), 1.30 (dt, J= 13.7, 6.9 Hz, 1H), 1.41 - 1.49 (m, 1H), 1.69-1.81 (m, 1H), 3.73 (m, 1H), 3.76 (s, 3H), 4.08-4.18 (m, 1H), 5.08 (s, 1H), 6.78 (s, 4H), 7.22-7.26 (m, 1H), 7.91 (d, J = 2.7 Hz, 1H).

[0255] S.6. Synthesis of / V2-(4-methoxyphenyl)- / \ / 5-(4-methylpentan-2-yl)pyridine-2,5-diamine (Comparative compound CC.5)

[0256] Compound C.4 was synthesized according to the procedure provided in Synthesis Example S.2 using Intermediate IC.1 (17.3 g, 81.3 mmol, 1.0 equiv) and p-anisidine (10.0 g, 81.3 mmol, 1.0 equiv) giving access to C.4 (18.2 g, 60.8 mmol, 75% yield) as dark red liquid.

[0257] 1H-NMR (400 MHz, CDCI3) 6 = 0.92 (t, J = 6.8 Hz, 6H), 1.13 (d, J = 6.2 Hz, 3H), 1.23 (dt, J =

[0258] 13.7, 6.9 Hz, 1H), 1.45 (dt, J= 13.9, 7.0 Hz, 1H), 1.75 (dp, J= 13.4, 6.7 Hz, 1H), 2.76-3.11 (m, 1H), 3.40 (h, J = 6.4 Hz, 1H), 3.78 (s, 3H), 6.19 (s, 1H), 6.66 (dd, J= 15.8, 8.8 Hz, 1H), 6.81 -6.91 (m, 3H), 7.11 -7.19 (m, 2H), 7.65 (d, J=2.8Hz, 1H).

[0259] 5.7. Synthesis of / V5-(4-(dimethylamino)phenyl)- / \ / 2 / V2-dimethylpyrimidine-2,5-diamine (Comparative compound CC.6)

[0260] In a four necked round bottom flask set under argon, 5-(di-tert-butylphosphaneyl)-T,3',5'-tri- phenyl-1'H-1,4'-bipyrazole (1.00 g, 1.98 mmol, 0.04 equiv) and Pd2(dba)s (0.45 g, 0.50 mmol, 0.01 equiv) and 2-methyl-2-butanol (50 mL) were mixed. Subsequently powdered potassium BASF SE 240613

[0261] 32 hydroxide (4.17 g, 74.2 mmol, 1.5 equiv) and water (1 mL) were added. The mixture was stirred at room temperature for 20 minutes. Then, 5-bromo- / V, / V-dimethylpyrimidin-2-amine (10.0 g, 49.5 mmol, 1.0 equiv) and / V / V7-dimethylbenzene-1 ,4-diamine (7.42 g, 54.4 mmol, 1.1 equiv) were added and the mixture was heated to an outer temperature of 120°C resulting to an inner temperature of 90°C. After 20 hours, the reaction mixture was filtered over silica after dilution with ethyl acetate. After washing the organic solution once with water, the water was extracted with ethyl acetate thrice. The combined organic layers were dried (Na2SO4) and after removal of the solvent in vacuo, the crude product was purified by column chromatography (silica, cyclohexane I ethyl acetate gradient). The product (10.3 g, 40.0 mmol, 81 % yield) was isolated as a dark yellow solid.

[0262] 1 H-NMR (400 MHz, CDCI3) 5 = 2.77 (s, 6H), 3.07 (s, 6H), 6.62 - 6.69 (m, 2H), 6.71 - 6.78 (m, 2H), 7.14 (s, 1 H), 8.15 (s, 2H).

[0263] S.8. Synthesis of / V2-(4-methylpentan-2-yl)- / \ / 5-phenyl-pyridine-2,5-diamine (Comparative Compound CC.2)

[0264] CC.2

[0265] Comparative Compound CC.2 was synthesized according to the procedure provided in Synthesis Example S.2 using Intermediate IC.2 (7.00 g, 32.9 mmol, 1.0 equiv.) and aniline (3.07 g, 32.9 mmol, 1.0 equiv.) giving access to CC.2 (6.10 g, 22.6 mmol, 69% yield) as dark brown solid.

[0266] 1H-NMR (400 MHz, CDCI3) 6 = 6 0.93 (d, J = 6.7 Hz, 1 H), 0.95 (d, J = 6.7 Hz, 1 H), 1.20 (d, J = 6.3 Hz, 1 H), 1.25 - 1.37 (m, 1 H), 1.41 - 1.50 (m, 1 H), 1.69 - 1.83 (m, 1 H), 3.70 - 3.85 (m, 1 H), 4.19 - 4.28 (m, 1 H), 5.31 (s, 1 H), 6.37 (d, J = 8.8 Hz, 1 H), 6.78 (ddd, J = 8.7, 7.4, 1.3 Hz, 3H), 7.14 - 7.23 (m, 2H), 7.33 (dd, J = 8.8, 2.7 Hz, 1 H), 7.97 (d, J = 2.6 Hz, 1 H) ppm.

[0267] S.9. Synthesis of / V5-(4-methylpentan-2-yl)- / \ / 2-phenyl-pyridine-2,5-diamine (Comparative Compound CC.3)

[0268] CC.3

[0269] Comparative Compound CC.3 was synthesized according to the procedure provided in Synthesis Example S.2 using Intermediate IC.1 (14.4 g, 67.7 mmol, 1.0 equiv.) and aniline (6.30 g, 67.7 mmol, 1.0 equiv.) giving access to CC.3 (15.1 g, 56.1 mmol, 83% yield) as red-brown oil. BASF SE 240613

[0270] 33

[0271] 1H-NMR (400 MHz, CDCI3) 6 = 0.92 (d, J = 6.6 Hz, 3H), 0.94 (d, J = 6.6 Hz, 3H), 1.15 (d, J = 6.2 Hz, 3H), 1.26 (dt, J = 13.7, 6.9 Hz, 1 H), 1.40 - 1.52 (m, 1 H), 1.67 - 1.83 (m, 1 H), 2.91 - 3.19 (m, 1 H), 3.37 - 3.50 (m, 1 H), 6.22 (s, 1 H), 6.80 - 6.96 (m, 3H), 7.14 - 7.31 (m, 4H), 7.70 (d, J = 2.4 Hz, 1 H) ppm.

[0272] S.10. Synthesis of 6-chloro- / \ / -isopropyl-pyridin-3-amine (Intermediate IC.3)

[0273] 5-Amino-2-chloropyridine (15.0 g, 117 mmol, 1.0 equiv.) and acetone (13.6 g, 233 mmol, 2.0 equiv.) were dissolved in methanol (350 mL). Acetic acid (28.0 g, 467 mmol, 4.0 equiv.) was added and the mixture was stirred at room temperature for 10 minutes. Sodium cyanoborohy- dride (14.7 g, 233 mmol, 2.0 equiv.) was added in portions and the mixture was heated to reflux for 16 hours, after which HPLC control showed 90% product. The reaction mixture was poured into ammonia solution and extracted with ethyl acetate thrice. The combined organic layers were washed with brine, dried over Na2SC>4 and freed from all volatiles in vacuo. The crude product was purified by column chromatography (silica, cyclohexane I ethyl acetate gradient with 1% NEta) which gave access to Intermediate IC.3 (16.9 g, 99.0 mmol, 85% yield) as a yellow oil that solidified over time.

[0274] 1H-NMR (400 MHz, CDCI3) 6 = 1.20 (d, J = 5.9 Hz, 6H), 3.52 - 3.62 (m, 2H), 6.82 (dd, J = 8.6,

[0275] 3.1 Hz, 1 H), 7.04 - 7.07 (m, 1 H), 7.71 (d, J = 2.9 Hz, 1 H) ppm.

[0276] S.11. Synthesis of / V5-isopropyl- / \ / 2-(5-methoxy-2-pyridyl)pyridine-2,5-diamine (Inventive Compound C.3)

[0277] C.3

[0278] Compound C.3 was synthesized according to the procedure provided in Synthesis Example S.2 using Intermediate IC.3 (12.5 g, 73.3 mmol, 1.0 equiv.) and 2-amino-5-methoxypyridine (9.09 g, 73.3 mmol, 1.0 equiv.) giving access to C.3 (10.0 g, 38.6 mmol, 53% yield) as dark-brown solid. BASF SE 240613

[0279] 34

[0280] 1H-NMR (400 MHz, CDCI3) 5 = 1.20 (d, J = 6.3 Hz, 6H), 2.91 - 3.32 (bs, 1 H), 3.49 - 3.63 (m, 1 H), 3.81 (s, 3H), 6.96 (dd, J = 8.8, 2.9 Hz, 1 H), 7.18 (dd, J = 9.0, 3.0 Hz, 1 H), 7.25 - 7.37 (m, 3H), 7.71 (d, J = 2.9 Hz, 1 H), 7.92 (d, J = 3.0 Hz, 1 H) ppm.

[0281] S.12. Synthesis of / V5-isopropyl- / V2-(6-methoxy-3-pyridyl)pyridine-2,5-diamine (Inventive Compound C.4)

[0282] C.4

[0283] Compound C.4 was synthesized according to the procedure provided in Synthesis Example S.2 using Intermediate IC.3 (12.8 g, 74.7 mmol, 1.0 equiv.) and 5-amino-2-methoxypyridine (9.28 g, 74.7 mmol, 1.0 equiv.) giving access to C.4 (7.50 g, 29.0 mmol, 39% yield) as dark-brown oil.

[0284] 1H-NMR (500 MHz, CDCI3) 6 = 1.18 (d, J = 6.3 Hz, 6H), 2.37 - 3.33 (bs, 1 H), 3.51 (hept, J = 6.3 Hz, 1 H), 3.90 (s, 3H), 6.14 (s, 1 H), 6.57 - 6.62 (m, 1 H), 6.67 - 6.73 (m, 1 H), 6.88 (dd, J = 8.8, 2.9 Hz, 1 H), 7.60 (dd, J = 8.8, 2.8 Hz, 1 H), 7.64 (d, J = 2.8 Hz, 1 H), 8.07 (d, J = 2.8 Hz, 1 H) ppm.

[0285] S.13. Synthesis of 5-chloro- / \ / -isopropyl-pyridin-2-amine (Intermediate IC.4)

[0286] 2-Amino-5-chloropyridine (15.0 g, 117 mmol, 1.0 equiv.) and acetone (13.6 g, 233 mmol, 2.0 equiv.) were dissolved in methanol (350 mL). Acetic acid (28.0 g, 467 mmol, 4.0 equiv.) was added and the mixture was stirred at room temperature for 10 minutes. Sodium cyanoborohy- dride (14.7 g, 233 mmol, 2.0 equiv.) was added in portions and the mixture was heated to reflux for 16 hours. HPLC control showed 35% product, additional sodium cyanoborohydride (5.00 g, 75.9 mmol, 0.65 equiv) and acetone (13.0 g, 223 mmol, 1.9 equiv.) were added and the mixture was stirred at reflux for 24 h. The reaction mixture was poured into ammonia solution and extracted with ethyl acetate thrice. The combined organic layers were washed with brine, dried over Na2SC>4 and freed from all volatiles in vacuo. The crude product was purified by column chromatography (silica, cyclohexane I ethyl acetate gradient with 1% NEta) which gave access to Intermediate IC.4 (10.4 g, 60.9 mmol, 52% yield) as a yellow oil that solidified over time. BASF SE 240613

[0287] 35

[0288] 1H-NMR (400 MHz, CDCI3) 6 = 1.21 (d, J = 6.4 Hz, 5H), 3.83 (m, 1 H), 4.31 - 4.51 (m, 1 H), 6.28 (d, J = 8.9 Hz, 1 H), 7.33 (dd, J = 8.9, 2.6 Hz, 1 H), 8.00 (d, J = 2.5 Hz, 1 H) ppm.

[0289] S.14. Synthesis of / V2-isopropyl- / V5-(6-methoxy-3-pyridyl)pyridine-2,5-diamine (Inventive Compound C.5)

[0290] C.5

[0291] Compound C.5 was synthesized according to the procedure provided in Synthesis Example S.2 using Intermediate IC.4 (10.0 g, 58.6 mmol, 1.0 equiv.) and 5-amino-2-methoxypyridine (7.28 g, 58.6 mmol, 1.0 equiv.) giving access to C.5 (7.30 g, 28.3 mmol, 48% yield) as dark-grey solid.

[0292] 1H-NMR (400 MHz, CDCI3) 5 = 1.23 (d, J = 6.4 Hz, 6H), 3.78 - 3.89 (bs, 1 H), 3.88 (s, 3H), 4.17 - 4.41 (bs, 1 H), 6.36 (d, J = 8.8 Hz, 1 H), 6.64 (d, J = 8.8 Hz, 1 H), 7.17 (dd, J = 8.8, 3.0 Hz, 1 H), 7.22 (dd, J = 8.8, 2.8 Hz, 1 H), 7.77 (d, J = 2.9 Hz, 1 H), 7.89 (d, J = 2.7 Hz, 1 H) ppm.

[0293] S.15. Synthesis of / V2-isopropyl- / \ / 5-(5-methoxy-2-pyridyl)pyridine-2,5-diamine (Inventive Compound C.6)

[0294] C.6

[0295] Compound C.6 was synthesized according to the procedure provided in Synthesis Example S.2 with double the amount of BippyPhos (0.08 equiv.) and Pd2(dba)s (0.02 equiv.) using Intermediate IC.4 (8.40 g, 49.2 mmol, 1.0 equiv.) and 2-amino-5-methoxypyridine (6.11 g, 49.2 mmol, 1.0 equiv.) giving access to C.6 (4.50 g, 17.4 mmol, 35% yield) as light-brown solid.

[0296] 1H-NMR (400 MHz, CDCI3) 5 = 1.24 (d, J = 6.4 Hz, 5H), 3.78 (s, 2H), 3.81 - 3.92 (m, 1 H), 4.24 - 4.41 (m, 1 H), 5.96 - 6.01 (m, 1 H), 6.38 (d, J = 8.8 Hz, 1 H), 6.49 - 6.54 (m, 1 H), 7.08 (dd, J = 9.0, 3.0 Hz, 1 H), 7.43 (dd, J = 8.8, 2.7 Hz, 1 H), 7.85 (d, J = 2.8 Hz, 1 H), 8.03 (d, J = 2.6 Hz, 1 H) ppm. BASF SE 240613

[0297] 36

[0298] C. Compound Examples

[0299] Table C.1 . Inventive antidegradant compounds and comparative compounds BASF SE 240613

[0300] 37

[0301] T. Testing Examples

[0302] Several test systems are available in order to either predict or evaluate the efficacy and the ef- fectivity of antiozonants.

[0303] For instance, antiozonant migration and antiozonation longevity tests may be assessed by grading the surface ozone cracks on a prepared rubber sample (partially comprising and partially not comprising an antiozonant) after exposure to ozone environment, e.g.in an ozone chamber for a specified duration. P.1 Preparation of SBR rubber compositions:

[0304] Table F.1. Components of the rubber composition BASF SE 240613

[0305] 38

[0306] Rubber compounds were prepared by mixing the components on a Werner&Pfleiderer GK 1,5 E internal mixer at a filling degree of 70%, a rotational speed of 50 min-1and a set temperature of 40 °C according to the general recipe provided in Table B.1 above and in the sequence described herein below.

[0307] To 137.50 phr of an emulsion styrene butadiene rubber (containing 37.5 phr TRAE (treated residual aromatic extract) extender oil and produced by cold emulsion polymerization: SBR Buna SE 1793, obtainable from Arlanxeo), 3 phr ZnO, 2 phr stearic acid and 2 phr of oligomeric 2,2,4- trimethyl-1,2-dihydroquinoline (Vulkanox HS, which is = TMQ, obtainable from Lanxess) is added in a first step. In the second and also as a third step, in total 70 phr of Carbon Black N 234 is added, which is followed as a fourth step by the addition of 1.75 phr sulfur, 1 phr of / V-cy- clohexyl-2-benzothiazyl sulfonamide (Vulkacit CZ obtainable from Lanxess) and 0.4 phr of diphenylguanidine. Finally, the respective antidegradant is added, which is either the reference compound or one of the inventive compounds.

[0308] The resulting rubber compounds were then vulcanized at 160 °C to yield 2 mm sample plaques which were cut into 100 x 15 mm2stripes.

[0309] P.2 Preparation of NR / BR rubber compositions

[0310] Vulcanized rubber compositions based on natural rubber and butyl rubber were prepared according to standard procedures used in the rubber industry.

[0311] An exemplary rubber composition is summarized in Table F.2. In a first step, the rubber components were blended in a 300 mL lab mixer with carbon black, oil, phenolic resin, stearic acid, Vulkanox HS, ozone protection wax, and antidegradant for 10 min at 160 °C. In a second step, sulfur, zinc oxide, and TBBS were added at 100 °C for 5 min.

[0312] Plaques were prepared by vulcanization of the rubber blends at 160 °C for 15 min under pressure.

[0313] Table F.2. Components of the NR / BR rubber compositions BASF SE 240613

[0314] 39

[0315] The vulcanized plaques of 2 mm thickness were then evaluated with respect to blooming of the antidegradants. T.1 Static ozone crack resistance test (according to DIN ISO 1431-1:2017-04)

[0316] 3 stripes per formulation were subjected to a static ozone crack resistance test according to DIN ISO 1431-1 :2017-04 at 23 °C and 55% relative humidity without any pre-conditioning, applying 20% strain and an ozone concentration of 50 pphm.

[0317] The samples were evaluated after 12 h exposure time with respect to their crack density and crack size according to the scheme outlined in Table S.1 (following DIN ISO 1431-1:2017-04 Appendix C):

[0318] Table S.1. Evaluation scheme for samples after static ozone crack resistance tes BASF SE 240613

[0319] 40

[0320] T.2 Tensile test (according to DIN 53504:2017-03)

[0321] Dumbbell-shaped test specimen of type S3 were die-cut from the ozone-exposed vulcanized rubber stripes and subjected to a tensile test according to DIN 53504:2017-03 at 23 °C and a speed of 200 mm / min. The tensile strength and elongation at break were recorded and the rela- tive changes calculated versus the respective values before ozone exposure, based on the median value out of 3 tensile tests each per formulation.

[0322] T.3 Dynamic ozone crack resistance test (according to DIN ISO 1431-1:2017-04)

[0323] 2 stripes per formulation were subjected to a dynamic ozone crack resistance test according to ISO 1431-1 :2024-07 at 23 °C and 35 °C, respectively. The relative humidity was 55%. Samples were pre-conditioned at 50% strain for 2 h at 23 °C in an ozone-free environment. The dynamic ozone test was performed applying 0-20% strain at a frequency of 0.5 Hz at an ozone concentration of 50 pphm.

[0324] The samples were evaluated after different exposure times ranging from 1 to 24 h with respect to their crack density and crack size according to the scheme outlined in Table S.1.

[0325] R. Results

[0326] ASF SE 240613

[0327] 41 able R.1. Results of static ozone crack resistance test (T.1 ) of vulcanized SBR rubber compositions after 12 h ozone exposure and change of tensi properties (T.2) before and after ozone test for comparative compounds (*3 specimen each): able R.2. Results of static ozone crack resistance test (T.1) of vulcanized SBR rubber compositions and change of tensile properties (T.2) before a after ozone test for inventive compounds (*3 specimen each):

[0328] ASF SE 240613

[0329] 42 able R.3. Results of dynamic ozone crack resistance test (T.3) of vulcanized SBR rubber compositions for comparative compounds at 23 °C (*2 specimen each): able R.4. Results of dynamic ozone crack resistance test (T.3) of vulcanized SBR rubber compositions for inventive compounds at 23 °C (*2 specimen ea

[0330] ASF SE 240613

[0331] 43 able R.5. Results of dynamic ozone crack resistance test (T.3) of vulcanized SBR rubber compositions for comparative compounds at 35 °C (*2 specimen each): able R.6. Results of dynamic ozone crack resistance test (T.3) of vulcanized SBR rubber compositions for inventive compounds at 35 °C (*2 specimen ea

[0332] BASF SE 240613

[0333] 44

[0334] Table R.7. Evaluation of blooming on vulcanized NR / BR rubber compositions

[0335] Comparison of results in the static ozone resistance test with Inv. Ex.1 in Table R.2 to those with Comp. Ex. 4 in Table R.1 shows that Inventive Compound C.1 gave smaller crack size after 12 h of ozone exposure and thus offers better protection against the detrimental influence of ozone compared to Comparative Compound CC.3. This finding was confirmed by the results of the dynamic ozone resistance tests at 23 °C and 35 °C as can be seen from Inv. Ex. 1 in Tables R.4 and R.6 versus Comp. Ex. 4 in Tables R.3 and R.5. At 23 °C, the time to formation of large cracks (as indicated by the rating “3”) was enhanced by the presence of A / -pyridyl-substituted Inventive Compound C.1 in Inv. Ex. 1 versus the respective A / -phenyl-substituted Comparative Compound CC.3 in Comp. Ex. 4. At 35 °C, Inventive Compound C.1 prolonged the time to formation of a high crack density (as indicated by the rating “N”) versus the respective A / -phenyl-substituted Comparative Compound CC.3.

[0336] The same trend was observed when comparing the rubber composition from Inv. Ex. 2 to the rubber compositions of Comp. Ex. 5 and Comp. Ex. 6 comprising the comparative compounds CC.4 and CC.5, respectively. The presence of the p-methoxy-substituted A / -pyridyl group in Inventive Compound C.2 present in Inv. Ex. 2 provides the rubber formulation with a very significantly improved resistance to ozone under both, static and dynamic, load conditions versus the respective Comparative Compounds CC. in Comp. Ex. 5 and CC.5 in Comp. Ex. 6 which both exhibit a non-heteroaro- matic p-methoxy-substituted A / -phenyl group.

[0337] Thus, it is concluded that the presence of a heteroaromatic, preferably substituted A / -pyridyl substituent in heteroaromatic diaminopyridy antidegradants is beneficial for the desired efficacy against the detrimental influence of ozone on vulcanized rubber articles compared to the presence of the respective, optionally substituted, non-heteoraromatic A / -phenyl substituents.

[0338] Furthermore, it can be learned from the results of Inv. Ex. 1 and Inv. Ex. 2 in Tables R.2, R.4 and R.6 that the introduction of an alkoxy substituent at the ancillary A / -pyridyl group further enhances the ozone protective ability of Inventive Compound C.2 versus Inventive Compound C.1 whose A / -pyridyl group does not have an alkoxysubstituent.

[0339] Therefore, it is concluded that the introduction of an electron-donating group such as an alkoxy group in the A / -py ridyl substituent in para position to the diamino-heteroaryl group, increases the antidegradant performance of the A / -heteroaromatic diamin-pyridyl derivatives as defined herein.

[0340] As can further be seen from Table R.7, although Comparative Compound CC.6, which has been disclosed by WO2012 / 162818 as an antioxidant for organic polymers, provides some ozone resistance to SBR rubber as can be seen from the results of the static ozone crack resistance test in Table R.1 , it shows strong blooming in the tested NR / BR rubber composition BASF SE 240613

[0341] 45 which is an undesired behavior and points to low compatibility with the rubber matrix. In comparison, the Inventive Compounds C.1 and C.2 show no blooming in the NR / BR rubber composition and therefore exhibit good compatibility with the rubber matrix.

Claims

BASF SE 24061346CLAIMS1. A rubber composition stabilized against effects of ozonation comprising antidegradant or antiozonant compounds of formula (II)whereinX1, X2, X3, X4, X5, X6, X7and X8are each either N or the group CH, and wherein at maximum one of X1, X3, X5and X7is N and at maximum one of X2, X4, X6and X8is N, andR1is selected from a group consisting of linear or branched Ci-Cw-alkyl, Cs-Cw-cycloalkyl, or a CyCw-arylalkyl which is bonded to the respective nitrogen atom of formula (I) via a Ci-C4-alkyl radical;R1’ is selected from hydrogen or a group consisting of linear or branched Ci-Cw-alkyl, Cs-C -cycloalkyl, or a CyCw-arylalkyl which is bonded to the respective nitrogen atom of formula (I) via a Ci-C4-alkyl radical;R2is selected from a group consisting of hydrogen, linear or branched Ci-Cw-alkyl, Cs-Cw-cycloalkyl, OR3or NR4R5, and whereinR3is selected from hydrogen, a linear or branched Ci-Cw-alkyl group or a Cs-Cw-cycloalkyl groupR4, R5are both independently from one another selected either from hydrogen, a linear or branched Ci-Cw-alkyl group or a Cs-Cw-cycloalkyl group, orR4and R5, together with the nitrogen atom they are bonded to, form a 5- to 9-membered saturated heterocyclic ring which may be unsubstituted or substituted with one or more Ci-C4-alkyls.

2. An antidegradant or antiozonant compound of formula (I)BASF SE 24061347WhereinX1, X2, X3and X4are each either N or the group CH, and wherein one of X1or X3is N, and the other is a group CH, and one of X2or X4is N, and the other is a group CH; andR1is selected from a group consisting of linear or branched Ci-C -alkyl, C3-C10- cycloalkyl, or a CyCw-arylalkyl which is bonded to the respective nitrogen atom of formula (I) via a Ci-C4-alkyl radical;R1’ is hydrogenR2is selected from a group consisting of hydrogen, linear or branched Ci-Cw-alkyl, Cs-C -cycloalkyl, OR3or NR4R5, and whereinR3is selected from hydrogen, a linear or branched Ci-Cw-alkyl group or a Cs-Cw-cycloalkyl groupR4, R5are both independently from one another selected either from hydrogen, a linear or branched Ci-Cw-alkyl group or a Cs-C -cyclo- alkyl group, orR4and R5, together with the nitrogen atom they are bonded to, form a 5- to 9-membered saturated heterocyclic ring which may be unsubstituted or substituted with one or more Ci-C4-alkyls.

3. The antidegradant or antiozonant compound of formula (I) according to claim 2, wherein said antiozonant is of the following structures ofBASF SE 24061348 formula(1.3), orformula (1.4): (l.4)4. The antidegradant or antiozonant compound of formula (I) or of formula (II) according to claim 1 ,2 or claim 3, whereinR1is a Cs-Cs-alkyl bonded to the respective nitrogen atom via a secondary C-atom, a Cs-Cs-cycloalkyl or a CyCs-phenylalkyl which is bonded to the respective nitrogen atom via a Ci-C2-alkyl radical.

5. The antidegradant or antiozonant compound of formula (I) or of formula (II) according to claim 1 , 2, 3 or claim 4, whereinR2is selected from hydrogen or a linear or branched Ci-Cs-alkyl.

6. The antidegradant or antiozonant compound of formula (I) or of formula (II) according to claim 1 , 2, 3 or claim 4, whereinR2is OR3, and wherein R3is hydrogen, a linear or branched Ci-C4-alkyl group or a Cs- Cs-cycloalkyl group7. The antidegradant or antiozonant compound of formula (I) or of formula (II) according to claim 1, 2, 3 or claim 4, whereinR2is OR3, and wherein R3methyl or ethyl.

8. The antidegradant or antiozonant compound of formula (I) or of formula (II) according to claim 1 , 2,3 or claim 4, whereinR2is NR4R5, and R4, R5are independently from one another selected either from hydrogen or a linear or branched Ci-Cs-alkyl, orR4and R5, together with the nitrogen atom they are bonded to, form a 5- to 7-mem- bered saturated heterocyclic ring which may be unsubstituted or substituted with one or more Ci-C4-alkyls.

9. The antidegradant or antiozonant compound of formula (I) or of formula (II) according to claim 3, whereinR1is selected from a group consisting of / -propyl, 1-methyl-propyl, 1-methyl-butyl, 1- ethyl-propyl, 1,2-dimethyl-propyl, 1 ,2-dimethyl-butyl, 1,3-dimethyl-butyl; 1 ,2,2-trime- thyl-propyl, 1-ethyl-2-methyl-propyl, 1 -ethyl-butyl, 1-methyl-pentyl, 1,4-dimethyl-pen- tyl, 1-methyl-heptyl, 1-ethyl-hexyl, cyclohexyl, and a-methylbenzyl;R2is selected from a group consisting of methyl, ethyl, n-propyl, / -propyl, n-butyl, / -butyl, f-butyl , OR3or NR4R5, and whereinBASF SE 24061349R3is methyl;R4is methyl, / -propyl, or 1 ,3-dimethyl-butyl;R5is either hydrogen or methyl; orR4and R5, together with the nitrogen atom they are bonded to, form a 5- to 7- membered saturated unsubstituted heterocyclic ring.

10. The rubber composition according to claim 1 , comprising at least one antidegradant or antiozonant compound of formula (I) or (II) as defined in any of claims 1-9, which further contains a diene rubber, a reinforcing filler, a plasticizer and / or a vulcanization system.11 . The rubber composition according to claim 1 or 10, which contains at least a highly unsaturated diene rubber selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene, polybutadiene, natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), solution polymerized styrene-butadiene rubber (SSBR), emulsion polymerized styrene-butadiene rubber (ESBR), butyl rubber (HR), and halobutyl rubber and any combinations thereof.

12. The rubber composition according to any one of claims 1 , 10 or 11 , which contains a reinforcing filler selected from the group consisting of carbon blacks, silicas, graphene, graphite, and combinations thereof.

13. The rubber composition according to any one of claims 1 ,10 to 12, which contains a plasticizer selected from the group consisting of oils, resins, and combinations thereof.

14. The rubber composition according to any one of claims 1 , 10 to 13, which contains a vulcanization system comprising sulfur and an accelerator.

15. The rubber composition according to any one of claims 1 , 10 to 14, wherein the amount of the antiozonant is between 0.2 to 10 phr, preferably between 0.5 to 3 phr.

16. A vehicle tire comprising a stabilized rubber composition according to any one of claims 1 , 10 to 15, comprising at least one antidegradant or antiozonant compound of formula (I) or (II) as defined in any of claims 1-9.

17. A vehicle tire according to claim 16, wherein the rubber composition is comprised in one outer component, and wherein the outer component is preferably a tread, a side wall and / or a rhombus.

18. Use of the compound according to formula (I) or (II) as defined in any of claims 1 to 9 as an antidegradant and / or antiozonant in vehicle tires and / or technical rubber articles.

19. The use according to claim 18, wherein the rubber article is an air spring, bellow, conveyor belt, hose, rubber band, profile, a seal, a membrane, tactile sensors for medical applications or robot applications or a shoe sole or parts thereof.

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