Phenothiazine compounds, their preparation and their use as aging protectants, antioxidants, antiozonants and colorants in rubber blends and vehicle tires

Abstract

The invention relates to compounds, rubber mixtures containing the compounds, vehicle tires containing the rubber mixture in at least one component, methods for preparing the compounds and the use of the compounds as ageing agents and / or antioxidants and / or antiozonants and / or dyes. The compounds according to the invention have the formula I).

Description

Technical Field

[0001] The invention relates to a compound, a rubber mixture containing the compound, a vehicle tire comprising the rubber mixture in at least one component, a process for preparing the compound and the use of the compound as an ageing agent and / or antioxidant and / or antiozonant and / or dye. Background Art

[0002] Vehicle tires and industrial rubber articles are known to employ polymeric materials such as, among others, rubber.

[0003] In the case of long-term storage, and especially in target applications that are usually at high temperatures, natural rubber and synthetic polymers (such as IR, BR, SBR, ESBR, etc.), as well as natural and synthetic oils, fats and lubricants, undergo oxidation reactions, which have an adverse effect on the originally desired properties. Depending on the type of polymer, the polymer chains are shortened until the material liquefies or subsequently hardens.

[0004] Therefore, aging stabilizers play a decisive role in the durability of vehicle tires and other industrial rubber products.

[0005] Known aging stabilizers are aromatic amines, for example 6-PPD (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine), IPPD (N-isopropyl-N'-phenyl-p-phenylenediamine) or SPPD (N-(1-phenylethyl)-N'-phenyl-p-phenylenediamine).

[0006] These molecules can react with oxygen or ozone or with the free radicals formed (such as alkyl and alkyl peroxide radicals) and thus scavenge these and thus protect the rubber etc. from further oxidation reactions.

[0007] Aromatic amines have the disadvantage, however, that they are suspected to be carcinogenic and therefore harmful to health, in particular because aniline or its derivatives may be liberated.

[0008] Furthermore, the solubility of the aging stabilizer in the medium to be protected must be taken into account. A disadvantage of aging stabilizers such as IPPD is that they are poorly soluble in the rubber under certain circumstances and therefore migrate to the surface and form a usually colored film. This effect is known as "blooming"; the aging stabilizer blooms out of the corresponding rubber. In addition to the appearance, this has the disadvantage that the bloomed aging stabilizer is removed, for example by rainwater, with the result that the film is reformed by further migrating molecules, resulting in a continuous reduction in the concentration of the aging stabilizer in the medium to be protected. This leads to a poorer protective effect than would be the case without blooming and loss of aging stabilizer.

[0009] Weathering stabilizers that are particularly reactive with ozone and effectively scavenge it are also known as "antiozonants." Summary of the invention

[0010] The object of the present invention is to provide compounds which can be used, in particular, as ageing stabilizers in vehicle tires or other technical rubber products, thereby achieving an improved protective effect for these products over the prior art. In particular, the blooming behavior should be improved and at the same time compounds which are less hazardous to health than the prior art (aromatic amines) should be provided.

[0011] This object is achieved by a compound according to the invention as claimed in claim 1, by a rubber mixture according to the invention containing the compound and by a vehicle tire according to the invention comprising the rubber mixture according to the invention in at least one component. The object is further achieved by a process for preparing the compound and by the use of the compound as an ageing stabilizer and / or antioxidant and / or antiozonant.

[0012] The compound according to claim 1 can further be used as a dye.

[0013] The compound according to claim 1 has the formula I):

[0014] I)

[0015] Thus, the compound of formula I) is 3-(1,3-dimethylbutylamino)phenothiazine.

[0016] The compounds of formula I) are phenothiazine derivatives. Phenothiazines / their derivatives are used, inter alia, as drugs, for example for the treatment of Parkinson's disease, see US 20130315825 A1, and are less hazardous to health than aromatic amines such as 6PPD or IPPD.

[0017] However, phenothiazines themselves are not easily soluble in polymers (such as rubbers of vehicle tires or other industrial rubber products), thus leading to the described blooming problem. Therefore, the compounds according to the invention have the advantage of a better protective effect compared to phenothiazines.

[0018] At the same time, compared with known aging stabilizers (such as 6PPD), the compounds of formula I) according to the invention exhibit an improved protective effect, which is believed to be due in particular to, for example, increased reactivity to free radicals. However, the present invention should not be limited to a specific mechanism of action or a specific explanation.

[0019] US 3413291 discloses phenothiazine derivatives. However, the derivatives disclosed therein are also not easily soluble in rubber, such as N-isopropyl-10H-phenothiazine-3-amine. Therefore, the compounds of the present invention having formula I) show better solubility in polymers (such as rubber) compared to known phenothiazine derivatives due to the 1,3-dimethylbutyl group and therefore show improved protective effects.

[0020] CN 108069874 also discloses aging stabilizers based on phenothiazine derivatives. However, the derivatives disclosed therein are also partially R 2 A Schiff base of C═NR′ (R′ is not H, but hydrogen), as shown, for example, in formula S1).

[0021]

[0022] These materials are susceptible to hydrolysis and show low protection, presumably because there are no sp 3 -hybridized α-H atom (α-hydrogen atom), as shown in S2).

[0023]

[0024] Compared to such Schiff base phenothiazine derivatives, such as compounds of formula S1), the compounds of formula I) of the present invention therefore have the advantages of being more stable, less susceptible to hydrolysis and allowing for better protection effects.

[0025] CN 106590827 discloses phenothiazine derivatives having the formula S3):

[0026]

[0027] However, the compound of formula S3) has -S-CH 2 The disadvantage of the -NH- moieties is that, for example in rubber mixtures for vehicle tires, they can form / release mercaptans due to their easy hydrolysis, which can lead to undesired pre-crosslinking (scorching) of the rubber mixture.

[0028] CN 105272892 discloses an aging stabilizer as shown in formula S4), in which a phenol derivative is connected to a phenothiazine unit via a thioacetate and an amide linker. These linking units are also not conducive to use in rubber mixtures to be vulcanized, because thioacetates are end-capped mercaptans that decompose during vulcanization and can, for example, bond with diene-containing rubbers. In addition, the amide part lacks α-H atoms, which - as described above for formula S1) - reduces the effect of the aging stabilizer.

[0029]

[0030] CN 107935867 discloses an aging stabilizer as shown in Formula S5), which exhibits a free amine group (-NH 2 ). This increases the risk of premature crosslinking, also known as "scorch", in rubber mixtures (for example for vehicle tires or other technical rubber products).

[0031]

[0032] The compounds of the formula I) according to the invention are particularly suitable as aging stabilizers and / or antiozonants in vehicle tires and / or in industrial rubber articles and / or in oils and / or lubricants, such as, in particular, air springs, bellows, conveyor belts, belts, drive belts, hoses, rubber belts, profiles, seals, membranes, tactile sensors for medical or robotic applications, or shoe soles or parts thereof.

[0033] The compounds of the formula I) according to the invention are particularly suitable for producing rubber articles, in particular air springs, bellows, conveyor belts, belts, drive belts, hoses, rubber belts, profiles, seals, membranes, tactile sensors for medical or robotic applications, or shoe soles or parts thereof.

[0034] To use the compound according to formula I) in the preparation or substance, the compound is employed in a composition and is used in conjunction with the composition.

[0035] In vehicle tires or other technical rubber products, this is in particular a rubber mixture.

[0036] The invention further provides the use of compounds of formula I) according to the invention in oils and lubricants, such as in particular fuels or fluids for engines. Thus, the compounds according to the invention can be used in engines.

[0037] The present invention further provides the use of the compounds according to the formula I) according to the invention as dyes in fibers and / or polymers and / or paper and / or in paints and coatings.

[0038] The present invention therefore further provides a rubber mixture as mentioned above.

[0039] The rubber mixture according to the invention contains compounds of formula I). ​​The rubber mixture according to the invention can in principle be any rubber mixture in which the novel compounds of formula I) achieve improved properties, in particular increased durability, by aging stability and / or anti-ozonation action.

[0040] The rubber mixture of the invention contains at least one rubber.

[0041] It is preferred when the rubber mixture according to the invention contains 0.1 to 10 phr, particularly preferably 0.1 to 5 phr, very particularly preferably 1 to 5 phr of a compound of the formula I).

[0042] The unit "phr" (parts per hundred parts of rubber by weight) used in this document is a conventional indication of the amount of a mixture formulation in the rubber industry. The dosages of parts by weight of the individual substances are in this document based on 100 parts by weight of the total mass of all high molecular weight (Mw greater than 20 000 g / mol) and therefore solid rubber present in the mixture.

[0043] In an advantageous embodiment of the invention, the rubber mixture according to the invention contains at least one diene rubber.

[0044] Thus, the rubber mixture may contain a diene rubber or a mixture of two or more different diene rubbers.

[0045] Diene rubber is a rubber formed by polymerization or copolymerization of a diene and / or a cycloolefin, and thus has a C═C double bond in the main chain or a side group.

[0046] The diene rubber is preferably selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), epoxidized polyisoprene (ENR), butadiene rubber (BR), butadiene-isoprene rubber, solution polymerized styrene-butadiene rubber (SSBR), emulsion polymerized styrene-butadiene rubber (ESBR), styrene-isoprene rubber, polyisoprene rubber having a molecular weight M greater than 20 000 g / mol ... w Liquid rubber, halogenated butyl rubber, polynorbornene, isoprene-isobutylene copolymer, ethylene-propylene-diene rubber, nitrile rubber, chloroprene rubber, acrylate rubber, fluororubber, silicone rubber, polysulfide rubber, epichlorohydrin rubber, styrene-isoprene-butadiene terpolymer, hydrogenated acrylonitrile butadiene rubber and hydrogenated styrene-butadiene rubber.

[0047] In particular, nitrile rubber, hydrogenated acrylonitrile-butadiene rubber, chloroprene rubber, butyl rubber, halogenated butyl rubber and / or ethylene-propylene-diene rubber are used in the production of industrial rubber products such as belts, transmission belts and hoses, and / or shoe soles. Preferably, mixture compositions for these rubbers that are specific and known to those skilled in the art are used in terms of fillers, plasticizers, vulcanization systems and additives.

[0048] The natural polyisoprene and / or synthetic polyisoprene of all embodiments can be cis-1,4-polyisoprene or 3,4-polyisoprene. However, preference is given to using cis-1,4-polyisoprene with a cis-1,4 ratio of >90% by weight. Such polyisoprene can firstly be obtained by stereospecific polymerization in solution with a Ziegler-Natta catalyst or using finely dispersed alkyl lithium. Secondly, natural rubber (NR) is such a cis-1,4-polyisoprene, wherein the cis-1,4 content in the natural rubber is greater than 99% by weight.

[0049] Mixtures of one or more natural polyisoprenes with one or more synthetic polyisoprenes are furthermore conceivable.

[0050] In the context of the present invention, the term "natural rubber" is understood to mean the naturally occurring rubber that can be obtained from the Hevea rubber tree and "non-Hevea" sources. Non-Hevea sources include, for example, the Guayule shrub and dandelions such as, for example, TKS (Taraxacum rubber grass; Russian dandelion).

[0051] If the rubber mixture of the invention contains butadiene rubber (i.e. BR, polybutadiene), it can be of any type known to those skilled in the art. These include so-called high cis types and low cis types, polybutadiene having a cis content of not less than 90% by weight being referred to as high cis types, and polybutadiene having a cis content of less than 90% by weight being referred to as low cis types. An example of low cis polybutadiene is Li-BR (lithium catalyzed butadiene rubber) having a cis content of 20% to 50% by weight. Particularly good properties and low hysteresis of the rubber mixture are achieved with high cis BR.

[0052] The one or more polybutadienes used can be end-group modified and / or functionalized along the polymer chain by modification and functionalization. The modification can be selected from modifications with hydroxyl and / or ethoxy and / or epoxy and / or siloxane groups and / or amino and / or aminosiloxane and / or carboxyl and / or phthalocyanine groups and / or silane-sulfide groups. However, other modifications known to those skilled in the art, also referred to as functionalized, are also suitable. Metal atoms can be such functionalized components.

[0053] In the case where at least one styrene-butadiene rubber (styrene-butadiene copolymer) is present in the rubber mixture, it can be a solution-polymerized styrene-butadiene rubber (SSBR) or an emulsion-polymerized styrene-butadiene rubber (ESBR), and mixtures of at least one SSBR and at least one ESBR are also employable. The terms "styrene-butadiene rubber" and "styrene-butadiene copolymer" are used synonymously in the context of the present invention.

[0054] The styrene-butadiene copolymers used can be end-group modified and / or functionalized along the polymer chain by the modifications and functionalizations listed above for the polybutadienes.

[0055] The at least one diene rubber is preferably 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 (IIR) and halogenated butyl rubber.

[0056] In a particularly preferred embodiment of the present invention, the at least one diene rubber is selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), solution polymerized styrene-butadiene rubber (SSBR) and emulsion polymerized styrene-butadiene rubber (ESBR).

[0057] In a particularly advantageous embodiment of the invention, the rubber mixture contains at least one natural polyisoprene (NR), preferably in an amount of 5 to 55 phr, and in a particularly advantageous embodiment of the invention, in an amount of 5 to 25 phr, very particularly preferably 5 to 20 phr. Such a rubber mixture exhibits good processing properties and reversion stability as well as optimal tearing properties and optimal rolling resistance characteristics.

[0058] In a particularly advantageous embodiment of the invention, the rubber mixture contains at least one polybutadiene (BR, butadiene rubber), preferably in an amount of 10 to 80 phr, particularly preferably 10 to 50 phr, and in a particularly advantageous embodiment of the invention, in an amount of 15 to 40 phr. This achieves particularly good tear and wear properties and optimal braking characteristics of the rubber mixture according to the invention.

[0059] In a particularly advantageous embodiment of the invention, the rubber mixture contains at least one solution polymerized styrene-butadiene rubber (SSBR), preferably in an amount of 10 to 80 phr, particularly preferably 30 to 80 phr, and in a particularly advantageous embodiment of the invention, in an amount of 50 to 70 phr. This achieves particularly good rolling resistance properties of the rubber mixture according to the invention. In a particularly advantageous embodiment of the invention, the SSBR is used in combination with at least one further rubber to achieve an optimal and balanced distribution of properties.

[0060] It is preferred that the rubber mixture contains at least one filler, preferably in an amount of 30 to 500 phr, particularly preferably 50 to 400 phr, further preferably 80 to 300 phr.

[0061] In an advantageous embodiment of the invention, the filler is a reinforcing filler preferably selected from the group consisting of carbon black and silica.

[0062] In a particularly advantageous embodiment of the invention, the rubber mixture contains at least one silicon dioxide as filler, preferably in an amount of 30 to 500 phr, particularly preferably 50 to 400 phr, and even more preferably 80 to 300 phr.

[0063] In these amounts, silica is especially present as the sole or main filler (greater than 50% by weight based on the total filler amount).

[0064] In a further advantageous embodiment of the invention, the rubber mixture contains at least one silicon dioxide as an additional filler, preferably in an amount of 5 to 100 phr, particularly preferably 5 to 80 phr, and even more preferably 10 to 60 phr.

[0065] In these amounts, silica is present in particular as a further filler in addition to another primary filler, such as in particular carbon black.

[0066] The silica may be any type of silica known to the person skilled in the art as being suitable as a filler for tire rubber mixtures. However, particular preference is given to using finely divided precipitated silica having a molecular weight of 35 to 400 m 2 / g, preferably 35 to 350m 2 / g, more preferably 85 to 320m 2 / g and most preferably 120 to 235m 2 / g nitrogen surface area (BET surface area) (according to DIN ISO 9277 and DIN 66132), and 30 to 400 m 2 / g, preferably 30 to 330m 2 / g, more preferably 80 to 300m 2 / g and most preferably 115 to 200 m 2 / g of CTAB surface area (according to ASTM D 3765). Such silica, for example, produces particularly good physical properties of the vulcanized product in rubber mixtures for tire treads. Advantages in the processing of the mixture by reducing the mixing time can also be produced here, while retaining the same product properties, which leads to improved productivity. The silica used can therefore be, for example, from Evonik Silica of the VN3 type (trade name) or highly dispersible silica known as HD silica (e.g. from Solvay) 1165MP).

[0067] In the case of the presence of at least two different silicas (which differ, for example, in their BET surface area) in the rubber mixture of the invention, the stated amount figures relate to the total amount of all silicas present.

[0068] The terms "silicic acid" and "silicon dioxide" are used synonymously in the context of the present invention.

[0069] The rubber mixture may additionally contain further fillers, such as in particular carbon black, in particular technical carbon black or pyrolytic carbon black, or further reinforcing or non-reinforcing fillers.

[0070] In the context of the present invention, further (non-reinforcing) fillers include aluminosilicates, kaolin, chalk, starch, magnesium oxide, titanium dioxide or rubber gel and also fibers (eg aramid fibers, glass fibers, carbon fibers, cellulose fibers).

[0071] Furthermore, optional reinforcing fillers are, for example, carbon nanotubes (CNTs), including discrete CNTs, hollow carbon fibers (HCFs) and modified CNTs containing one or more functional groups (such as hydroxyl, carboxyl and carbonyl groups), graphite and graphene, and so-called "carbon-silica dual-phase fillers".

[0072] In the context of the present invention, zinc oxide is not included among the fillers.

[0073] In a particularly advantageous embodiment of the invention, the rubber mixture according to the invention contains 0.1 to 60 phr, preferably 3 to 40 phr, particularly preferably 5 to 30 phr, very particularly preferably 5 to 15 phr of at least one carbon black. In these amounts, in addition to the main fillers, such as in particular silicon dioxide, carbon black is present in particular as an additional filler.

[0074] In a further advantageous embodiment of the present invention, the rubber mixture according to the present invention contains 30 to 300 phr, preferably 30 to 200 phr, particularly preferably 40 to 100 phr of at least one carbon black. In these amounts, the carbon black is present as the sole or main filler and is therefore optionally present in the above-mentioned lesser amount in combination with silica.

[0075] Suitable carbon blacks include any of the types of carbon blacks familiar to those skilled in the art.

[0076] In one embodiment, the carbon black has an iodine number (also referred to as iodine adsorption number) according to ASTM D 1510 of between 30 and 250 g / kg, preferably 30 to 180 g / kg, particularly preferably 40 to 180 g / kg and very particularly preferably 80 to 150 g / kg, and a DBP value according to ASTM D 2414 of 30 to 200 ml / 100 g, preferably 70 to 200 ml / 100 g, particularly preferably 90 to 200 ml / 100 g.

[0077] The DBP value according to ASTM D 2414 determines the specific absorption volume of carbon black or light-colored fillers by means of dibutyl phthalate.

[0078] The use of this type of carbon black in rubber mixtures, in particular for vehicle tires, ensures the best possible compromise between wear resistance and heat buildup, which in turn influences the ecologically relevant rolling resistance. It is preferred to use only one type of carbon black in the respective rubber mixture, but it is also possible to mix different types of carbon black into the rubber mixture.

[0079] In a particularly advantageous embodiment of the invention, the rubber mixture 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.

[0080] The rubber mixture may further contain conventional additives in conventional weight portions, which are preferably added in at least one primary mixing stage during the production of the mixture. These additives include

[0081] a) ageing stabilizers known from the prior art, for example diamines, such as N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl-p-phenylenediamine (DTPD), N-(1,4-dimethylpentyl)-N'-phenyl-p-phenylenediamine (7PPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), or dihydroquinolines, such as 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ),

[0082] b) activators, for example zinc oxide and fatty acids (for example stearic acid) and / or other activators, such as zinc complexes, for example zinc ethylhexanoate,

[0083] c) activators and / or agents for binding fillers, in particular carbon black or silicon dioxide, for example S-(3-aminopropyl)thiosulfate and / or its metal salts (binding of carbon black) and silane coupling agents (binding of silicon dioxide),

[0084] d) antiozonant wax,

[0085] e) resins, especially tackifying resins for tire interior parts,

[0086] f) plasticizing aids, such as 2,2'-dibenzamidodiphenyl disulfide (DBD), and

[0087] g) processing aids, such as in particular fatty acid esters and metal soaps, for example zinc soaps and / or calcium soaps,

[0088] h) Plasticizers, such as, in particular, aromatic, naphthenic or paraffinic mineral oil plasticizers, for example MES (mild extraction solvate) or RAE (residual aromatic extract) or TDAE (treated distillate aromatic extract), or rubber liquid oils (RTL) or biomass liquid oils (BTL) preferably having a polycyclic aromatic hydrocarbon content of less than 3% by weight according to method IP 346, or triglycerides, for example rapeseed oil or oil paste or hydrocarbon resins or liquid polymers having an average molecular weight (determined by GPC=gel permeation chromatography according to BS ISO 11344:2004) of between 500 and 20 000 g / mol.

[0089] When a mineral oil is used, it is preferably selected from the group consisting of DAE (Distillate Aromatic Extract) and / or RAE (Residual Aromatic Extract) and / or TDAE (Treatened Distillate Aromatic Extract) and / or MES (Mild Extracted Solvent) and / or naphthenic oil.

[0090] In a particularly advantageous embodiment, the rubber mixture according to the invention contains no further aging stabilizers from the group of p-phenylenediamines (see above list a)) in addition to the compound of formula I). ​​In a particularly preferred embodiment, the rubber mixture according to the invention contains in particular 0 to 0.1 phr, in particular 0 phr, of further aging stabilizers based on diamines selected from the group comprising, particularly preferably consisting of, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N-(1,4-dimethylpentyl)-N'-phenyl-p-phenylenediamine (7PPD).

[0091] Very small amounts of preferably 0 to 0 phr, particularly preferably 0 phr, of the abovementioned diamines and the compounds of formula I) present according to the invention enable improved protection. The compounds of formula I) according to the invention replace the listed diamines known from the prior art.

[0092] In a further advantageous embodiment of the invention, at least one further representative of the diamine aging stabilizer is present and the compounds according to the invention thus only partially replace the diamines known from the prior art. This also achieves the advantages according to the invention, but not to the optimal extent.

[0093] In an advantageous embodiment, in addition to the compounds of formula I) according to the invention, an aging stabilizer based on dihydroquinoline (such as TMQ) is present in the rubber mixture. The amount of dihydroquinoline (such as especially TMQ) present is preferably 0.1 to 3 phr, in particular 0.5 to 1.5 phr.

[0094] In a further advantageous embodiment, the rubber mixture according to the invention comprises no further aging stabilizers, ie 0 phr of further aging stabilizers other than the compound of the invention of formula I).

[0095] The silane coupling agent may be of any type known to those skilled in the art.

[0096] Furthermore, one or more different silane coupling agents can be used in combination with one another. The rubber mixture can therefore contain a mixture of different silanes.

[0097] Silane coupling agents react with surface silanol groups or other polar groups of silica during mixing of the rubber / rubber mixture (in situ) or in the context of pretreatment (premodification) even before adding fillers to the rubber.

[0098] Coupling agents known from the prior art are difunctional organosilanes which have at least one alkoxy, cycloalkoxy or phenoxy group as a leaving group on the silicon atom and a group as a further functional group which, possibly after cleavage, can enter into a chemical reaction with the double bonds of the polymer. The latter group may, for example, comprise the following chemical groups:

[0099] -SCN, -SH, -NH 2 or -S x -(where x=2 to 8).

[0100] Thus, silane coupling agents that can be used include, for example, 3-mercaptopropyltriethoxysilane, 3-thiocyanatopropyltrimethoxysilane or 3,3'-bis(triethoxysilylpropyl)polysulfides having 2 to 8 sulfur atoms, such as 3,3'-bis(triethoxysilylpropyl)tetrasulfide (TESPT), the corresponding disulfide (TESPD) or else mixtures of sulfides having 1 to 8 sulfur atoms with various sulfides in different contents. TESPT can also, for example, be used as a carbon black (trade name TESPD from Evonik) as a coupling agent. ) was added to the mixture.

[0101] End-capped mercaptosilanes, as are known, for example, from WO 99 / 09036, can also be used as silane coupling agents. It is also possible to use silanes as described in WO 2008 / 083241 A1, WO 2008 / 083242 A1, WO 2008 / 083243 A1 and WO 2008 / 083244 A1. It is also possible to use, for example, the silanes sold in various variants under the name NXT by Momentive, USA, or under the name VP Si The following are those sold by Evonik Industries.

[0102] The total proportion of further additives is preferably from 3 to 150 phr, more preferably from 3 to 100 phr and most preferably from 5 to 80 phr.

[0103] Zinc oxide (ZnO) may be included in the above-mentioned amount in the total ratio of the other additives.

[0104] This can be any type of zinc oxide known to the person skilled in the art, for example ZnO granules or powder. Conventionally used zinc oxides usually have a BET surface area of ​​less than 10 m2 / g. However, it is also possible to use zinc oxides with a BET surface area of ​​10 to 100 m2 / g, for example so-called "nano zinc oxide".

[0105] The rubber mixtures according to the invention are preferably used in vulcanized form, in particular in vehicle tires or other vulcanized industrial rubber articles.

[0106] The vulcanization of the rubber mixture of the present invention is preferably carried out in the presence of sulphur and / or sulphur donors with the aid of vulcanization accelerators, some of which may simultaneously act as sulphur donors. The accelerator is selected from the group consisting of thiazole accelerators and / or thiol-containing accelerators and / or sulfenamide accelerators and / or thiocarbamate accelerators and / or thiuram accelerators and / or thiophosphate accelerators and / or thiourea accelerators and / or xanthate accelerators and / or guanidine accelerators.

[0107] It is preferred to use a sulfonamide accelerator selected from the group consisting of N-cyclohexyl-2-benzothiazolesulfenamide (CBS) and / or N,N-dicyclohexylbenzothiazole-2-sulfenamide (DCBS) and / or benzothiazolyl-2-sulfenomorpholide (MBS) and / or N-tert-butyl-2-benzothiazolylsulfenamide (TBBS) or a guanidine accelerator such as diphenylguanidine (DPG).

[0108] The sulfur-donating substance used may be any sulfur-donating substance known to the person skilled in the art. If the rubber mixture contains a sulfur-donating substance, the latter is preferably selected from the group comprising, for example, thiuram disulfides, such as tetrabenzylthiuram disulfide (TBzTD) and / or tetramethylthiuram disulfide (TMTD) and / or tetraethylthiuram disulfide (TETD), and / or thiuram tetrasulfides, such as dipentamethylenethiuram tetrasulfide (DPTT), and / or dithiophosphates, such as

[0109] DipDis (bis(diisopropyl)phosphorothioate disulfide) and / or bis(O,O-2-ethylhexylphosphorothioate) polysulfide (e.g. Rhenocure SDT Rheinchemie GmbH) and / or zinc dichlorooxydithiophosphate (e.g. Rhenocure ZDT / Rhein Chemie) and / or zinc alkyl dithiophosphates and / or 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane and / or diaryl polysulfides and / or dialkyl polysulfides.

[0110] Such as, for example, a trademark The further network-forming systems obtained or as described in WO 2010 / 049216 A2 can also be used in the rubber mixture. Such systems contain a vulcanizing agent which crosslinks with a functionality greater than four and at least one vulcanization accelerator.

[0111] Particular preference is given to using the accelerators TBBS and / or CBS and / or diphenylguanidine (DPG).

[0112] Vulcanization retarders may also be present in the rubber mixture.

[0113] The terms "vulcanized" and "cross-linked" are used synonymously in the context of the present invention.

[0114] In a preferred development of the invention, accelerators are added in the final mixing stage during the production of the sulfur-crosslinkable rubber mixture.

[0115] Sulfur cross-linkable rubber mixture of the present invention is produced by the usual method in the rubber industry, wherein the basic mixture of all the ingredients except the vulcanization system (sulfur and the material that affects the vulcanization) is first produced in one or more mixing stages. The final mixture is produced by adding the vulcanization system in the last mixing stage. For example, the final mixture is further processed and made into a suitable shape by means of extrusion operation or calendering.

[0116] This is followed by further processing by vulcanization, wherein, due to the addition of a vulcanization system in the context of the present invention, sulfur crosslinking occurs.

[0117] The above-described rubber mixtures of the invention are particularly suitable for use in vehicle tires, in particular pneumatic vehicle tires.

[0118] For use in vehicle tires, the mixture as a final mixture before vulcanization is preferably brought into the shape of a tread and applied in a known manner during the production of a green vehicle tire.

[0119] As already described, the production of rubber mixture of the present invention is carried out, and this rubber mixture is used as the sidewall or other body mixture of vehicle tire.The difference is the shaping after the extrusion operation / calendering of the mixture.The shape of the rubber mixture not yet vulcanized for one or more different body mixtures thus obtained is then used for the construction of green tire.

[0120] Here, "body mixture" refers to the rubber mixture for the internal components of the tire, such as mainly rubber rollers, inner liner (inner layer), ring core profile, belt, tire shoulder, belt profile, carcass, bead reinforcement, bead profile, flange profile and hoop. The uncured green tire is subsequently vulcanized.

[0121] In order to use the rubber mixture of the invention in drive belts and other belts, in particular in conveyor belts, the extruded, not yet vulcanized mixture is brought into a suitable shape and is generally provided simultaneously or subsequently with strength members, such as synthetic fibers or steel cords. This generally provides a multilayer construction consisting of one and / or more layers of rubber mixture, one and / or more layers of identical and / or different strength members and one and / or more further layers of identical and / or another rubber mixture.

[0122] The invention further provides a vehicle tire which comprises, in at least one component, a rubber mixture according to the invention, which contains the compound according to the invention.

[0123] The vulcanized vehicle tire comprises at least one vulcanized rubber of rubber mixture according to the present invention in at least one component.Those skilled in the art know that most materials (for example existing rubber) exist in the form of chemical change after mixing or only after vulcanization.

[0124] Within the context of the present invention, "vehicle tyres" are understood to mean vehicle pneumatic tyres and solid rubber tyres, including tyres for industrial and construction site vehicles, trucks, cars and two-wheeled vehicle tyres.

[0125] The vehicle tire according to the invention preferably comprises the rubber mixture according to the invention in at least one external component, wherein the external component is preferably the tread, the sidewall and / or the flange profile.

[0126] The vehicle tire according to the invention can therefore also comprise in two or more components a rubber mixture according to the invention with an optionally suitable composition, which contains the compound of the formula I) according to the invention.

[0127] The present invention further provides a process for preparing a compound of formula I), wherein the process comprises at least the following process steps:

[0128] a) providing a substance having the formula A)

[0129]

[0130] b) Providing methyl isobutyl ketone (MIBK) and hydrogen (H 2 );

[0131] c) reacting the substance according to step a) with the substance according to step b), preferably in the presence of a hydrogenation catalyst, to obtain a substance having formula I)

[0132]

[0133] The present invention further provides a further process for preparing a compound of formula I), wherein the process comprises at least the following process steps:

[0134] a1) providing a substance having the formula A)

[0135]

[0136] b1) providing a reducing agent, in particular tin(II) chloride dihydrate;

[0137] c1) reacting the substance according to step a1) with the substance from step b1) to obtain a substance having formula C1)

[0138]

[0139] d1) provides methyl isobutyl ketone (MIBK) and hydrogen (H 2 );

[0140] e1) reacting a substance of formula C1) with a hydrogenation catalyst according to step d1), preferably in the presence of a hydrogenation catalyst, to obtain a substance of formula I)

[0141]

[0142] The substance methyl isobutyl ketone (MIBK) is commercially available.

[0143] The reducing agent may be any reducing agent known to those skilled in the art and suitable for reducing the nitro group (NO 2 ) is reduced to an amino group (-NH 2 Tin(II) chloride dihydrate is particularly suitable. This is commercially available.

[0144] The process of steps a) to c) is preferred over the process of steps a1) to e1) because fewer process steps are required.

[0145] Preference is given to the process step in which the reaction with hydrogen is carried out using a suitable catalyst, which is referred to in the context of the present invention as a "hydrogenation catalyst".

[0146] The hydrogenation catalyst of the process (step c) / e1)) is preferably a noble metal catalyst, such as in particular palladium (Pd) or platinum (Pt). The noble metal is preferably employed on carbon (C), such as palladium on carbon (Pd / C) or platinum on carbon (Pt / C).

[0147] Other known catalysts such as Raney nickel or copper chromite may also be used.

[0148] Preference is given to using Pt / C in step c).

[0149] Preference is given to using Pd / C in step e1).

[0150] The hydrogen pressure in the corresponding process steps using hydrogen is preferably 1 to 50 bar, particularly preferably 10 to 45 bar. According to an advantageous embodiment of the invention, a pressure of 20 to 40 bar is preferred.

[0151] The hydrogenation reaction in step c) / e1) is preferably carried out in an autoclave, in particular in a stainless steel autoclave.

[0152] The temperature in process steps c) and e1) is preferably from room temperature (RT, in particular 20°C) to 150°C, preferably 130°C.

[0153] The present invention further provides a further process for preparing a compound of formula I), wherein the process comprises at least the following process steps:

[0154] a2) providing a substance having the formula A2):

[0155]

[0156] b2) providing elemental sulfur and o-dichlorobenzene (ortho-dichlorobenzene);

[0157] c2) reacting the material of step a2) with the material of step b2) to obtain a material having formula I)

[0158] BRIEF DESCRIPTION OF THE DRAWINGS

[0159] Figure 1a and Figure 1b The cleavage mechanism is shown. DETAILED DESCRIPTION

[0160] The present invention will be described in more detail below with reference to working examples.

[0161] The component having formula I) is prepared as follows:

[0162] X1): The compound of the invention having the formula I) (3-(1,3-dimethylbutyl) is synthesized according to process steps a) to c) Amino)phenothiazine):

[0163]

[0164] 0.50 g (2.05 mmol, 1 equivalent) 3-nitrophenothiazine, 0.18 g platinum on carbon (5%) (0.4 g on 4.67 mmol substrate) and 20.0 mL methyl isobutyl ketone were weighed into a stainless steel autoclave equipped with a Teflon liner. The autoclave was then pressurized to 40 bar with hydrogen and stirred at 120° C. for 10 hours. After the reaction was terminated, excess hydrogen was blown off and the suspension was passed through diatomaceous earth. Filter and wash with ethanol. Concentrate the filtrate to dryness and dry in vacuo. Light grey to purple solid; yield 0.57 g (93% of theory).

[0165] 1 H-NMR (500MHz, DMSO-d6) δ=8.09(s,1H),6.94(td,J=7.6,1.5Hz,1H),6.88(dd,J=7.6,1.4Hz,1H ),6.69-6.63(m,2H),6.51(d,J=8.4Hz,1H),6.27(dd,J=8.5,2.5Hz,1H),6.21(d,J=2.5Hz,1H),4 .82(d,J=8.9Hz,1H),3.30(dt,J=8.6,6.5Hz,1H),1.70(dp,J=13.5,6.7Hz,1H),1.38(dt,J=13. 9,7.1Hz,1H),1.16(dt,J=13.5,6.8Hz,1H),1.02(d,J=6.1Hz,3H),0.87(dd,J=19.4,6.6Hz,6H).

[0166] 13 C-NMR (126MHz, DMSO-d6)δ=144.5,143.9,131.8,127.7,126.6,121.0,117 .6,116.5,115.8,114.4,112.1,110.7,46.5,46.4,25.0,23.2,23.0,21.2.

[0167] ESI-MS (electrospray ionization mass spectrometry) [M+H] + =299.

[0168] In a further experiment X2), the reaction was carried out as described above, but with the difference that, although the autoclave was likewise pressurized to 40 bar with hydrogen, the mixture was stirred at 40° C. for 3 hours.

[0169] Similar yields were obtained as shown in Table 1 below.

[0170] Table 1

[0171]

[0172] The starting material 3-nitrophenothiazine of formula A) described according to the above method was prepared according to the disclosure in US 20130315825A1.

[0173] Alternatively, 3-nitrophenothiazine can be prepared by a one-step copper (Cu) catalyzed synthesis as disclosed in WO 2017011531 A2 (page 217). 3-nitrophenothiazine can be further obtained by a non-catalytic reaction disclosed in S. Wu, W. Hu, S. Zhang, RSC Advances, 2016, 6 (29), 24257-24260. 3-nitrophenothiazine can be further obtained from phenothiazine by reacting with sodium nitrite as disclosed in WO 2007110627A2.

[0174] Alternatively, starting from 3-nitrophenothiazine, substances of the formula I) are obtained in two steps according to process steps a1) to e1):

[0175] Synthesis of 3-aminophenothiazine:

[0176]

[0177] Under protective gas, 22 g (90.0 mmol, 1.0 equivalent) of 3-nitrophenothiazine was weighed, dissolved in 800 mL of ethanol, mixed with 102 g (534 mmol, 5.0 equivalent) of tin (II) chloride dihydrate, and stirred for 4 days under boiling heat. Once the reaction reached room temperature (RT), one third of the solvent was distilled off and the remainder was poured onto ice. Subsequently, the pH of the mixture was adjusted to pH = 7 using an aqueous potassium hydroxide solution and extracted three times with ethyl acetate. The organic phase was washed with a saturated NaCl solution and then filtered through Na 2 SO 4 After drying, a brown solid was obtained; yield 18.9 g (98% of theory). 1 H-NMR (500MHz, DMSO-d6) δ = 8.08 (s, 1H), 6.94 (td, J = 7.7, 1.5Hz, 1H), 6.88 (dd, J = 7.7 ,1.5Hz,1H),6.71-6.60(m,2H),6.46(d,J=8.3Hz,1H),6.32-6.22(m,H),4.64(s,2H).

[0178] ESI-MS [M+H] + =215.

[0179] Synthesis of 3-(1,3-dimethylbutylamino)phenothiazine:

[0180]

[0181] 5.00 g (23.3 mmol, 1 equivalent) of 3-aminophenothiazine, 2.00 g of palladium on carbon (5%) (0.4 g on 4.67 mmol of substrate) and 50.0 mL of methyl isobutyl ketone were weighed into a stainless steel autoclave lined with Teflon. The autoclave was then pressurized to 40 bar with hydrogen and stirred at 120° C. for 10 hours. After the reaction was terminated, excess hydrogen was blown off and the suspension was passed through diatomaceous earth. Filter and wash with ethanol. Concentrate the filtrate to dryness and dry in vacuo. Light grey to purple solid; yield 6.61 g (95% of theory).

[0182] 1 H-NMR (500MHz, DMSO-d6) δ=8.09(s,1H),6.94(td,J=7.6,1.5Hz,1H),6.88(dd,J=7.6,1.4Hz,1H ),6.69-6.63(m,2H),6.51(d,J=8.4Hz,1H),6.27(dd,J=8.5,2.5Hz,1H),6.21(d,J=2.5Hz,1H),4 .82(d,J=8.9Hz,1H),3.30(dt,J=8.6,6.5Hz,1H),1.70(dp,J=13.5,6.7Hz,1H),1.38(dt,J=13. 9,7.1Hz,1H),1.16(dt,J=13.5,6.8Hz,1H),1.02(d,J=6.1Hz,3H),0.87(dd,J=19.4,6.6Hz,6H).

[0183] 13 C-NMR (126MHz, DMSO-d6)δ=144.5,143.9,131.8,127.7,126.6,121.0,117 .6,116.5,115.8,114.4,112.1,110.7,46.5,46.4,25.0,23.2,23.0,21.2.

[0184] ESI-MS [M+H] + =299.

[0185] Alternatively, the substances of the formula I) are obtained in one step according to process steps a2) to c2):

[0186] Synthesis of 3-(1,3-dimethylbutylamino)-phenothiazine:

[0187]

[0188] Under protective gas, 10 g (37.3 mmol, 1 equivalent) of 6-PPD (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) was dissolved in 80 mL of degassed o-dichlorobenzene and mixed with 2.9 g (89 mmol, 2.4 equivalents, based on monomer "S") of sulfur and 0.95 g (3.73 mmol, 0.1 equivalent) of iodine (I 2 ) was mixed. The mixture was heated at reflux (180°C) for 4 hours. The hydrogen sulfide formed was passed into a 5% NaOH solution. Once cooled to room temperature (RT), the mixture was mixed with dichloromethane (DCM) and saturated Na 2 S 2 O 3 The resulting black solid was removed by filtration, and the organic phase was separated from the aqueous phase. The organic phase was washed with saturated NaCl solution and then purified by Na 2 SO 4 Dry and concentrate to dryness. The black solid was analyzed by UV-VIS spectroscopy (ultraviolet and visible spectroscopy) coupled with LC-MS (liquid chromatography-mass spectrometry). It contains 39% (E)-N-(4-methylpentan-2-yl)-3H-phenothiazine-3-imine by-product (lower molecule on the right side of the reaction arrow) and 24% of unidentified substances. The remaining 37% is composed of starting materials and compounds of formula I of the present invention.

[0189] The compounds of the present invention having formula I) exhibit an increased reactivity relative to 6PPD. This is for example related to the binding dissociation energy (BDE) and the free activation enthalpy Δ R G ≠ and the free standard reaction enthalpy Δ R These values ​​are reported in Table 2. Figure 1a and Figure 1b The cracking mechanism is shown, with values ​​related to:

[0190] Table 2

[0191] molecular BDE[kJ / mol] <![CDATA[Δ R G°[kJ / mol]]]> <![CDATA[Δ R G ≠ [kJ / mol]]]> 6PPD 313 -25.6 19.1 Formula I) 251 -52.8 6.3

[0192] It is clear from Table 2 that the compounds of the present invention having formula I) have lower bond dissociation energy and lower free enthalpy.

[0193] The compounds of the formula I) therefore make it possible to achieve an improved protective effect in the applications mentioned.

[0194] For use in rubber mixtures for vehicle tires, the compounds of the invention with formula I) are added in a mixing stage in the production of the rubber mixture in a manner known to the person skilled in the art, for example instead of the aging stabilizers known in the prior art, such as 6PPD, 7PPD or IPPD etc.

Claims

1. A compound having formula I):

2. A rubber mixture comprising the compound of formula I) as claimed in claim 1.

3. The rubber mixture as claimed in claim 2, It is characterized in that The rubber mixture contains at least one diene rubber.

4. The rubber mixture as claimed in claim 3, It is characterized in that The rubber mixture contains at least one diene rubber selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), solution polymerized styrene-butadiene rubber (SSBR), emulsion polymerized styrene-butadiene rubber (ESBR), butyl rubber (IIR) and halogenated butyl rubber.

5. A vehicle tire comprising the rubber mixture as claimed in any one of claims 2 to 4 in at least one component.

6. The vehicle tire according to claim 5, It is characterized in that The vehicle tire contains at least one rubber mixture as claimed in any one of claims 2 to 4 in at least one outer component.

7. The vehicle tire according to claim 6, It is characterized in that The external component is a tread, sidewall and / or flange profile.

8. A method for preparing a compound of formula I) as claimed in claim 1, wherein include: At least the following method steps: a) providing a substance having the formula A) b) Providing methyl isobutyl ketone (MIBK) and hydrogen (H 2 ); c) reacting the substance according to step a) with the substance according to step b) to obtain the substance having formula I) 9. A method for preparing a compound of formula I) as claimed in claim 1, wherein include: At least the following method steps: a1) providing a substance having the formula A) b1) providing a reducing agent; c1) reacting the substance according to step a1) with the substance from step b1) to obtain a substance having formula C1) d1) provides methyl isobutyl ketone (MIBK) and hydrogen (H 2 ); e1) reacting the substance of formula C1) with the substance according to step d1) to obtain the substance of formula I) 10. The method according to claim 9, It is characterized in that The reducing agent is tin(II) chloride dihydrate.

11. A method for preparing a compound of formula I) as claimed in claim 1, wherein include: At least the following method steps: a2) providing a substance having the formula A2): b2) providing elemental sulfur and o-dichlorobenzene; c2) reacting the substance according to step a2) with the substance according to step b2) to obtain the substance of formula I) 12. Use of a compound of formula I) as claimed in claim 1 as an ageing stabilizer and / or antiozonant in technical rubber products and / or oils and / or lubricants.

13. The use according to claim 12, It is characterized in that These industrial rubber products are vehicle tires, air springs, bellows, belts, hoses, profiles, seals, membranes, tactile sensors for medical applications or robotic applications, or shoe soles or parts thereof.

14. Use of a compound of formula I) as claimed in claim 1 in a fuel for engines.

15. Use of a compound of the formula I) as claimed in claim 1 as a dye in fibers and / or polymers and / or paper and / or in coatings.

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