Sulfur-crosslinkable rubber composition, sulfur-vulcanized rubber composition, rubber product, and tire thereof

Abstract

The present invention relates to a sulfur-crosslinkable rubber composition, a sulfur-vulcanized rubber composition obtainable from the respective sulfur-crosslinkable rubber composition, a rubber product comprising said sulfur-vulcanized rubber composition as well as a tire thereof.

Description

[0001] Description

[0002] Sulfur-crosslinkable rubber composition, sulfur-vulcanized rubber composition, rubber product, and tire thereof

[0003] The present invention relates to a sulfur-crosslinkable rubber composition, a sulfur-vulcanized rubber composition obtainable from the respective sulfur-crosslinkable rubber composition, a rubber product comprising said sulfur-vulcanized rubber composition as well as a tire thereof.

[0004] The subject-matter of the present invention is defined in the claims below.

[0005] Since the start of the twenty-first century, the automotive industry is one of the industrial branches that is facing the most fundamental challenges and is experiencing several disruptive technological advances. The growing customer awareness for ecological aspects like emission profiles or resource efficiency requires new concepts for mobility. At the same time, there is an ever-increasing demand for improved performance characteristics of vehicles as well as overall stricter regulations with respect to safety. Meeting these challenges is not only a task for vehicle manufacturers. In fact, several of these aspects are heavily influenced by the properties of the vehicle tires, making the optimization of tire properties a key objective.

[0006] Several relevant properties of pneumatic vehicle tires, e.g. rolling resistance, hardness, and wear resistance (abrasion), are closely linked to the rubber composition of the tread. Therefore, a lot of research effort is focused on optimizing the properties of such compositions. In fact, significant progress was made in recent years, e.g. by replacing carbon black filler with silica. Unfortunately, a lot of different physical-chemical properties of sulfur-vulcanized rubber compositions that are relevant for the running properties of tires cannot be altered independently of each other, resulting in trade-offs, wherein one property cannot be enhanced without adversely affecting another relevant property. For instance, an improvement in wet grip and dry braking generally entails deterioration in rolling resistance, winter properties and abrasion characteristics. In consequence, the optimization of rubber compositions is oftentimes about resolving the trade-offs by developing solutions for increasing specific parameters without hampering the respective complementary properties too severely.

[0007] An essential ingredient in sulfur-crosslinkable rubber compositions are rubber polymers. Over time, especially such polymers became target of intensive research to identify modifications, e.g. by means of incorporating functional groups, such that certain properties are particularly improved. Typically, such modifications can be present to various extents. For example, a polymer chain, typically having two terminal ends, can be a single-end modified polymer chain or dual-end modified polymer chain. Additionally or alternatively, also the polymer backbone can be modified. Typically, such modifications and functional groups, respectively, are designed to specifically interact with a filler material or another ingredient of the composition. For example, while some functional groups are designed to specifically interact with silica, other functional groups are specifically designed to interact with carbon black. Depending on the overall rubber composition, such a modified polymer can specifically bind to silica, carbon black or both filler materials in the composition.

[0008] However, the more functional groups are present in a respective polymer, the more likely it is that such a polymer undergoes undesired side reactions such as an undesired cross-linking before mixing or premature binding to the filler material during mixing. This is typically not desired, particularly the premature binding during mixing. Particularly, dual-end modified polymers often show a tendency to prematurely bind excessively to its respective filler material during mixing such that the mixing cannot completed. Although such polymers are theoretically promising in improving physical-chemical properties, they often cannot be used.

[0009] In view of the above-described background, it is the objective of the present invention to overcome said disadvantages and to provide a sulfur- crosslinkable rubber composition providing improved physical-chemical properties by finding suitable dual-end modified polymers. It is very specifically the object to particularly further improve and better balance rolling and wear resistance (abrasion) of respective sulfur-vulcanized rubber compositions, rubber products, and particularly tires.

[0010] Furthermore, it was an objective of the present invention to provide a sulfur-crosslinkable rubber composition that exhibits an improved filler material affinity between the polymers and the filler material used in the sulfur-crosslinkable rubber composition.

[0011] The above-described objectives are solved by the subject-matter of the present invention, particularly by a sulfur-crosslinkable rubber composition comprising

[0012] (a) a filler component in a total amount ranging from 1 to 350 phr, and

[0013] (b) at least one modified conjugated diene-based polymer, which has one or more than one polymer chain each comprising a structural unit derived from a conjugated diene compound, each polymer chain having its terminal ends modified by a functional group either being a nitrogen-containing functional group or a sulfur- containing functional group, with the proviso that

[0014] A) - at least one terminal end of the terminal ends is modified by a nitrogen-containing functional group and at least another terminal end of the terminal ends is modified by a sulfur-containing functional group, and / or (preferably and)

[0015] - in each polymer chain having two corresponding terminal ends, one end is modified by a nitrogen-containing functional group and the other end is modified by a sulfur- containing functional group; or

[0016] B) - two, three or more than three polymer chains of the more than one polymer chain are bound to each other by means of either a nitrogen-containing functional group or a sulfur- containing functional group, each functioning as a linker group, and

[0017] - the functional groups modifying the terminal ends of the two, three or more than three polymer chains are (i) sulfur- containing functional groups if the linker group is a nitrogencontaining functional group or (ii) nitrogen-containing functional groups if the linker group is a sulfur-containing functional group.

[0018] In particular, the inventors found that the above-described objectives can be solved by utilizing a specific class of particularly dual-end / multi-end modified polymers as defined above, preferably as defined throughout the text. Without wishing to being bound by theory, said polymers have the advantage to not show extensive premature binding during mixing. Rather, only one end undergoes a premature binding while the other end is chemically bound not prior to sulfur-crosslinking (i.e. vulcanization). This still allows a very good handling during mixing. At the same time, physicalchemical properties such as rolling resistance, wear resistance (abrasion), and tensile stress are improved (see examples below) in respective rubber products, particularly in tires.

[0019] Hereinafter, the subject-matter of the present invention is discussed in more detail, wherein preferred embodiments of the invention are disclosed. It is particularly preferred to combine two or more preferred embodiments to obtain an especially preferred embodiment.

[0020] Correspondingly, especially preferred is a sulfur-crosslinkable rubber composition according to the invention defining two or more features of preferred embodiments of the present invention.

[0021] The term “sulfur-crosslinkable” is well known to the skilled person and defines that the rubber composition of the present invention can be cured (i.e. is curable) in the presence of sulfur such that the individual chains of the rubber polymers are crosslinked, i.e. interconnected, to obtain a cured rubber composition, i.e. sulfur-vulcanized rubber composition. This process is known as vulcanization and the obtained product is typically used to produce a broad variety of rubber products. This also means that the sulfur-crosslinkable rubber composition according to the present invention is not yet crosslinked, vulcanized, and cured, respectively.

[0022] In the context of the present invention, “phr” as used herein denotes “parts per hundred parts of rubber by weight” and is the standard unit used in the rubber industry to define the amounts of different components in a rubber composition. The respective amounts are given as parts by weight of the substance relative to the total mass of all high molecular weight rubbers present in the composition that are solid at ambient conditions and constitute 100 phr.

[0023] (a) the filler component:

[0024] The properties of the sulfur-crosslinkable rubber composition were found to be influenced by the choice of filler material used in the filler component The sulfur-crosslinkable rubber composition of the present invention comprises (a) a filler component in a total amount ranging from 1 to 350 phr. The filler component preferably comprises one or more filler material, more preferably selected from the group consisting of silica, carbon black, aluminosilicates, chalk, starch, magnesium oxide, titanium dioxide, rubber gels, graphite, graphene, hollow carbon fibers, and carbon nanotubes.

[0025] Own experiments have shown that excellent results were obtained with silica and / or carbon black. Therefore, preferred is a sulfur-crosslinkable rubber composition of the present invention, wherein the filler component comprises as filler material silica and / or carbon black.

[0026] In general, preferred is a sulfur-crosslinkable rubber composition of the present invention, comprising the filler component in a total amount ranging from 10 to 300 phr, preferably from 15 to 260 phr, more preferably from 20 to 220 phr, even more preferably from 25 to 180 phr.

[0027] In some cases, a sulfur-crosslinkable rubber composition of the present invention is preferred, wherein the filler component comprises carbon black as filler material, preferably being present in a total amount ranging from 10 to 300 phr, preferably from 15 to 250 phr, more preferably from 20 to 200 phr, even more preferably from 25 to 150 phr, yet even more preferably from 30 to 100 phr. Preferably in some cases, carbon black is the only filler material in the composition.

[0028] In some cases, a sulfur-crosslinkable rubber composition of the present invention is preferred, wherein the filler component comprises silica as filler material, preferably being present in a total amount ranging from 10 to 300 phr, preferably from 20 to 270 phr, more preferably from 30 to 240 phr, even more preferably from 40 to 210 phr, yet even more preferably from 50 to 180 phr. Preferably in some cases, silica is the only filler material in the composition.

[0029] Suitable silicas are known to the skilled person and e.g. disclosed in US 10273351 A1.

[0030] In some cases, preferred is a sulfur-crosslinkable rubber composition according to the invention, wherein the filler component comprises as filler material silica and carbon black, preferably in a weight ratio ranging from 100: 1 to 1 : 100, wherein the filler component preferably comprises at least 0.01 phr carbon black. Thus, in some cases it is preferred that more silica is present than carbon black. In other cases, it is preferred that more carbon black is present than silica. In some cases, it is preferred that the filler component comprises silica as filler material, preferably in a total amount of 90 wt.-% or more, based on the total weight of the filler component, more preferably of 95 wt.-% or more, most preferably of 98 wt.-% or more.

[0031] (b) the at least one modified conjugated diene-based polymer:

[0032] The sulfur-crosslinkable rubber composition of the present invention comprises (b) at least one modified conjugated diene-based polymer as defined above, preferably as defined throughout the present text.

[0033] Generally, the at least one modified conjugated diene-based polymer as defined in the context of the present invention is present in the sulfur- crosslinkable rubber composition either as alternative (A) or (B) or (A) in combination with (B).

[0034] In the context of the present text, “conjugated diene-based polymer” generally denotes a polymer based on (i.e. derived from, polymerized / copolymerized from) diene compounds (i.e. monomers), having conjugated carbon-carbon double bonds. In its polymerized state, they are forming said structural unit. Preferably, the one or more than one polymer chain (except the functional groups) is entirely or at least predominantly based on said structural unit, i.e. derived from diene compounds. Preferred diene compounds comprise isoprene, butadiene and / or styrene.

[0035] More preferably, the at least one modified conjugated diene-based polymer is a modified styrene-butadiene-based polymer, a modified isoprene-based polymer and / or a modified butadiene-based polymer, even more preferably a modified styrene-butadiene-based polymer or a modified butadiene-based polymer, most preferably a modified styrene- butadiene-based polymer.

[0036] The term “modified” denotes that the polymer comprises additionally (i.e. in addition to the structural unit derived from a conjugated diene compound) said functional groups at the terminals (i.e. ends) of the polymer. This means that said functional groups are at least monovalent functional groups. They are modifying the ends of the polymer chains. Since in each alternative (A) and (B) the polymer chains have terminal ends, such monovalent functional groups are present in both alternatives.

[0037] In the context of the present invention, terminal ends refer to all ends that can be subject to a modification by said functional groups. For example, in the simplest case, the at least one modified conjugated diene-based polymer has one polymer chain, resulting in two terminal ends, which are at the beginning and the end of the polymer chain. In such a case the whole polymer has as many ends as the one polymer chain. Furthermore, both ends are modified by a functional group, wherein one functional group is a nitrogen-containing functional group and the other functional group is a sulfur-containing functional group. Thus, both types of functional groups are present one time. In the context of the present invention, this scenario is particularly preferred for the sulfur-crosslinkable rubber composition of the present invention. This also represents the most preferred form for alternative (A).

[0038] In case of two polymer chains, two scenarios are imaginable, both falling under alternative (A). In the first scenario, one of the two polymer chains is a branch of the other polymer chain, meaning that one terminal end of one polymer chain is connected to the backbone of the other polymer chain (this terminal end is not modified by a functional group in the context of alternative (A)). This results in a total of three terminal ends, which are all modified by said functional groups, wherein at least one functional group is a nitrogen-containing functional group and at least one functional group is a sulfur-containing functional group. Thus, either two nitrogen-containing functional groups are present or two sulfur-containing functional groups are present. In addition, one polymer chain still has two terminal ends (typically the main chain, where the branch is starting from), being the corresponding terminal ends of this polymer chain (meaning, belonging to its respective polymer chain), wherein one terminal end is modified by a nitrogen-containing functional group and the other terminal end is modified by a sulfur-containing functional group.

[0039] In the second scenario, still falling under alternative (A), both polymer chains are connected to each other by backbone cross-linking such that a total of four terminal ends are present, which are all modified by said functional groups. Since both polymer chains have two corresponding terminal ends (meaning, belonging to its respective polymer chain), in each individual polymer chain one terminal end is modified by nitrogencontaining functional group and the other terminal end is modified by a sulfur-containing functional group. This results in a total of two nitrogencontaining functional groups and two sulfur-containing functional groups.

[0040] Furthermore, in the context of the present invention, the at least one modified conjugated diene-based polymer is in some cases alternatively or in addition present in a form falling under alternative (B). In this alternative, at least two polymer chains are present (i.e. a single polymer chain is preferably excluded), preferably two, three or four; most preferably two or three. The difference compared to alternative (A) is that the functional groups (preferably as defined throughout the present text) are not only modifying the terminal ends as monovalent functional groups but groups of the same kind also serve / function as an at least divalent (i.e. divalent, trivalent, tetravalent, or more, etc.; preferably divalent or trivalent) linker group. Its purpose is to bind the individual polymer chains together, preferably via / through covalent bonds. As a result, such a linker group is subsequently integrated within the diene-based polymer but no longer a terminal modifier in the completed polymer. Thus, the at least one modified conjugated diene-based polymer according to alternative (B) comprises more than one polymer chain (comprising the structural unit derived from a conjugated diene compound), the monovalent functional groups modifying the terminal ends of the polymer chains, and the at least divalent linker group binding the more than one polymer chain together. In the context of the present invention, the at least divalent linker group in alternative (B) is either a nitrogen-containing functional group or a sulfur- containing functional group, with the proviso that the monovalent functional groups modifying the terminal ends are not of the same category as the linker group. In other words, if the linker group is a nitrogen-containing functional group, the functional groups modifying the terminal ends are sulfur-containing functional groups and vice versa. For example, two polymer chains are connected to each other by a sulfur- containing functional group named “S-Si-1” (see also text below as well as Table 2, modified conjugated diene-based polymer A-17, A-18, and A-28) functioning as a divalent linker group for alternative (B), wherein the two polymer chains are bound with one end to a silicon atom of “S-Si-1”. The remaining two terminal ends of the polymer chains (one in each chain) are modified by a nitrogen-containing functional group. This results in a total of two monovalent nitrogen-containing functional groups at the terminal ends and a single divalent sulfur-containing functional group within the diene- based polymer.

[0041] Regarding alternative (B), it is preferred that the linker group is a sulfur containing functional group. More preferably the linker group is a sulfur- containing functional group and the functional groups modifying the terminal ends are monovalent nitrogen-containing functional groups.

[0042] Generally, the functional groups defined in the context of the present invention preferably either are modifying the terminal ends as monovalent functional groups or (if chemically applicable) are linking at least two polymer chains together as an at least divalent linker group.

[0043] In some cases, a modified conjugated diene-based polymer of alternative (A) is more preferred than of alternative (B).

[0044] In the context of the present invention, the nitrogen-containing functional groups and sulfur-containing functional groups are each individually independent from each other. This preferably means that, having for example two nitrogen-containing functional groups as described above for the second scenario, each nitrogen-containing functional group is either different or identical. As mentioned, this principle applies likewise to the sulfur-containing functional groups. Also, the kind of nitrogen-containing functional group is independent of the kind of sulfur-containing functional group, and vice versa.

[0045] Preferably, in the context of the present invention, a nitrogen-containing functional group does not comprise a sulfur atom.

[0046] Preferably, in the context of the present invention, a sulfur-containing functional group (i) does (i.e. must) comprise at least one sulfur atom, and (ii) does not comprise further nitrogen atoms or does comprise additionally one or more than one nitrogen atom. This means that the sulfur-containing functional groups as defined in the context of the present invention are defined by the presence of at least one sulfur atom and irrespective of the presence of additional nitrogen atoms. For example, the bis(dimethylamino)thiobenzophenone moiety (see text below) is such a sulfur-containing functional group although it contains additional amino groups. Thus, thioketone moieties in the context of the present invention are counted among the sulfur-containing functional groups due to the presence of a sulfur atom and irrespective of the presence of additional amino atoms. More preferably, the compound classes mentioned below further specifying the sulfur-containing functional groups are explicitly considered / defined as sulfur-containing functional groups, irrespective of having additional nitrogen atoms.

[0047] The way of synthesizing examples of modified conjugated diene-based polymers is explained in more detail in the examples section below. Preferably, in the at least one modified conjugated diene-based polymer the conjugated diene compounds are distributed statistically (i.e. randomly).

[0048] Preferably, the at least one conjugated diene-based polymer is a copolymer, i.e. it is based on two or more different diene compounds having conjugated double bonds, i.e. monomers having a different chemical structure but still being conjugated dienes.

[0049] Preferred is a sulfur-crosslinkable rubber composition of the present invention, wherein

[0050] - in the at least one modified conjugated diene-based polymer the conjugated diene compound comprises butadiene compounds and / or (preferably and) styrene compounds, and / or

[0051] - the at least one modified conjugated diene-based polymer has a styrene content ranging from 0 to 50 wt.-%, based on the total weight of the polymer, preferably from 5 to 50 wt.-%, more preferably from 5 to 40 wt.- %, even more preferably from 6 to 30 wt.-%, yet even more preferably from 6 to 20 wt.-%, most preferably from 7 to 15 wt.-%, and / or

[0052] - the at least one modified conjugated diene-based polymer has a vinyl content ranging from 10 to 80 wt.-%, based on the total weight of butadiene compounds, preferably from 15 to 65 wt.-%, more preferably from 20 to 60 wt.-%, even more preferably from 25 to 55 wt.-%, most preferably from 30 to 50 wt.-%.

[0053] The sulfur-crosslinkable rubber composition of the present invention shows a high affinity between the at least one modified conjugated diene- based polymer and the filler component. As a result thereof, a significantly improved performance is obtained after vulcanization, in particular an improved rolling resistance, wear resistance (abrasion), and tensile stress.

[0054] Preferred is a sulfur-crosslinkable rubber composition of the present invention, wherein in the at least one modified conjugated diene-based polymer the nitrogen-containing functional group comprises

[0055] -a N-hetero-cycloalkyl moiety having one, two or three ring-nitrogen atoms; preferably as a six-membered ring thereof; or

[0056] - an amino hydrocarbon moiety (equally referred to as an amino hydrocarbyl moiety) with a tertiary nitrogen atom.

[0057] Preferred is a sulfur-crosslinkable rubber composition of the present invention, wherein the N-hetero-cycloalkyl moiety having one, two or three ring-nitrogen atoms, comprises

[0058] - a piperidine moiety,

[0059] - a diazinane moiety, preferably a piperazine moiety, more preferably a 1 -silyl-piperazine moiety or a 1 -silylalkylpiperazine moiety, even more preferably a 1 -(trialkylsilyl)piperazine moiety or a 1 -(3-(dialkyl(tert-alkoxy)silyl)propyl)piperazine moiety, most preferably a 1 -(trimethylsilyl)piperazine moiety or a 1 -(3-(dimethyl(tert-butoxy)silyl)propyl)piperazine moiety; and / or

[0060] - a triazinane moiety, preferably a 1 ,3,5-triazinane moiety.

[0061] A preferred N-hetero-cycloalkyl moiety having one, two or three ring- nitrogen atoms is selected from the group consisting of compounds of formulae (1 ), (2), and (3)

[0062] wherein each independently

[0063] - R1, R2, R3, R4, and R5denotes independently a C1 to C10 hydrocarbylene group, preferably a C1 to C2 alkylene group;

[0064] - X1denotes a hydrocarbylene group or -N(A3)-, preferably a C1 alkylene group or -N(A3)-; and

[0065] - A1, A2, and A3denotes hydrogen, a trihydrocarbylsilyl group, or a C1 to C20 hydrocarbyl group; wherein

[0066] - A4denotes a C1 to C20 (i+k)-valent hydrocarbon group or a C1 to C20 (i+k)-valent group which has a nitrogen atom and no active hydrogen and which is bonded to each of the silicon atom and the nitrogen atom in formula (3) via a carbon atom;

[0067] - each of R6and R7independently denotes a C1 to C20 hydrocarbyl group;

[0068] - n1 is an integer of 0 to 2; - each of R8and R9independently denotes a C1 to C10 hydrocarbylene group;

[0069] - each of i and k is independently an integer of 1 to 6, wherein the condition i+k<10 is satisfied;

[0070] - if more than one R6is present, they are identical or different from one another;

[0071] - if more than one R7is present, they are identical or different from one another;

[0072] - if more than one R8is present, they are identical or different from one another; and

[0073] - if more than one R9s is present, they are identical or different from one another.

[0074] In some cases, a compound of formula (1 ) is preferred, wherein R1and R2is a C2 alkylene group and X1is a C1 alkylene group. This is a preferred piperidine moiety in the context of the present invention.

[0075] In some cases, a compound of formula (1 ) is preferred, wherein R1and R2is a C2 alkylene group and X1is a -N(A3)- group and A3preferably a trihydrocarby Isi ly I group. This is a preferred piperazine moiety in the context of the present invention.

[0076] In some cases, a compound of formula (3) is preferred, wherein R8and R9is a C2 alkylene group, A4is a C2 to C4 alkylene group, i is 1 , n1 is 1 or 2 (preferably 2), R6and R7are independently a C1 to C5 alkyl group. This is too a preferred piperazine moiety in the context of the present invention.

[0077] Preferred is a sulfur-crosslinkable rubber composition, wherein the amino hydrocarbon moiety with a tertiary nitrogen atom comprises

[0078] - a N,N-(dialkyl)aminohydrocarbon moiety with one or more than one double bond, preferably a reaction compound of 3-(dimethylamino)propyl lithium with isoprene; and / or

[0079] - a N,N-bis(silyl)aminoalkyl-silane moiety, preferably a N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane moiety

[0080] In the context of the present invention, the term “moiety” preferably denotes a base-structure from which the functional group is derived or based on. Thus, preferably the said moiety is preferably the compound for the respective modification of the terminal ends.

[0081] Besides the N-containing functional group, the at least one modified conjugated diene-based polymer also comprises a sulfur-containing functional group.

[0082] Preferred is a sulfur-crosslinkable rubber composition, wherein in the at least one modified conjugated diene-based polymer the sulfur-containing functional group is selected from the group consisting of

[0083] - a thiirane moiety;

[0084] - a carbon disulfide moiety;

[0085] - a hydrocarbylthiol moiety, preferably an alkene thiol moiety, most preferably a propene thiol moiety;

[0086] - a thioether moiety, preferably an aromatic thioether moiety, most preferably a phenyl vinyl sulfide moiety; - a thioester moiety;

[0087] - a dithioester moiety, preferably an aromatic dithioester moiety, most preferably a cumyl dithiobenzoate moiety;

[0088] - a thioketone moiety, preferably an aromatic thioketone moiety, most preferably a bis(dimethylamino)thiobenzophenone moiety, or preferably a branched aliphatic thioketone moiety, most preferably a di-te / t-butyl thioketone moiety;

[0089] - a dithiane moiety, preferably an alkyl dithiane moiety, most preferably a methyl-1 ,3-dithiane moiety;

[0090] - a dithiolane moiety;

[0091] - a thiophene moiety; and / or

[0092] - a dialkyl tin(IV) disulfide moiety or dialkyl silyl disulfide moiety, each comprising an alkoxy silyl group, preferably a dialkyl tin(IV) bis(alkoxysilyl alkyl sulfide) moiety.

[0093] Very preferably, the sulfur-containing functional group comprises a thiirane moiety or a thioketone moiety, preferably a thiirane moiety or a thioketone moiety as defined above as being preferred. The inventors found that in particular good results were obtained with the aforementioned more specific functional groups (see also examples below).

[0094] Preferably, said dialkyl tin(IV) disulfide moiety and dialkyl silyl disulfide moiety, each comprising an alkoxy silyl group, is very preferably an at least divalent functional group applied in alternative (B) as linker group and less preferred in alternative (A) as a monofunctional group.

[0095] Preferred is a sulfur-crosslinkable rubber composition, wherein the at least one modified conjugated diene-based polymer has a sulfur content in a range from 50 to 800 ppm, based on the total weight of said polymer, preferably from 65 to 675 ppm, more preferably from 80 to 550 ppm, even more preferably from 95 to 425 ppm, yet even more preferably from 110 to 300 ppm, most preferably from 125 to 250. In the context of the present invention, the sulfur content was determined by using a combustion ion chromatography (Combustion IC) analysis method utilizing measuring instrument AQF-21 OOH (Nittoseiko Analytech Co., Ltd.) under the following conditions:

[0096] - Combustion temperature: Inlet: 900°C, Outlet: 1000°C

[0097] - Gas flow rate: Argon 200 mL / min, Oxygen 400 mL / min

[0098] - Humidification: 0.23 mL / min, Internal Standard Material (PO4): 20 mg / kg

[0099] - Absorbent solution (hydrogen peroxide water): 900 mg / kg; volume of absorbent solution: 5 mL, Diluted volume of final absorbent solution: 10 mL

[0100] - Column: lonPac™ AS18 (Thermo Fisher Scientific Inc.)

[0101] - Eluents: 30.5 mM KOH aqueous solution

[0102] - Flow rate: 1 mL / min

[0103] - Detector: Suppressed Conductivity Detector, SRS

[0104] - Electric current: 76 mA

[0105] - Sample quantity: A 30 mg sample of a respective modified conjugated diene-based polymer was weighed into the sample boat, and a combustion aid (WO3) was added Preferred is a sulfur-crosslinkable rubber composition, wherein the at least one modified conjugated diene-based polymer has a nitrogen content in a range from 25 to 500 ppm, based on the total weight of said polymer, preferably from 50 to 420 ppm. In the context of the present invention, the nitrogen content was determined according to JIS K 2609: 1998 “Crude petroleum and petroleum products - Determination of nitrogen content”. This means that in a trace total nitrogen analyzer (instrument: TN-2100H (Mitsubishi Chemical Analytech, Co., Ltd.)) a sample of a respective modified conjugated diene-based polymer was completely pyrolyzed under argon gas flow and then subjected to oxidative combustion with oxygen gas. The nitrogen monoxide generated was oxidized by ozone gas under dehydration conditions, and the emission intensity detected between 590 and 2500 nm was measured. The nitrogen content was determined from the area under the emission intensity curve.

[0106] A sulfur-crosslinkable rubber composition according to the invention is preferred, wherein the at least one modified conjugated diene-based polymer has a weight average molecular weight Mwin a range from 50,000 to 2,000,000 g / mol, preferably from 70,000 to 1 ,500,000 g / mol, more preferably from 90,000 to 1 ,000,000 g / mol, even more preferably from 110,000 to 750,000 g / mol, yet even more preferably from 130,000 to 500,000 g / mol, most preferably from 130,000 to 300,000 g / mol.

[0107] In the context of the present invention, the weight-average molecular weight Mw referred to above is determined by means of gel permeation chromatography (GPC) with tetrahydrofuran (THF) as eluent at 40 °C in accordance with BS ISO 11344:2004.

[0108] Preferred is a sulfur-crosslinkable rubber composition of the present invention, wherein the at least one modified conjugated diene-based polymer according to (b) is present in a total amount ranging from 10 to 99 phr, preferably from 25 to 98 phr, more preferably from 40 to 97 phr. Very preferably, the total amount is more than 40 phr. Preferably, the modified conjugated diene-based polymer according to (b) is in the sulfur- crosslinkable rubber composition the major polymer species.

[0109] (c) the diene-based rubber polymer being different from (b):

[0110] The sulfur-crosslinkable rubber composition according to the invention can comprise other diene rubber compounds. Preferred is a sulfur- crosslinkable rubber composition of the present invention further comprising

[0111] (c) a diene-based rubber polymer being different from (b), preferably selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), polybutadiene (BR; butadiene rubber), styrene-butadiene copolymer (SBR, styrene-butadiene rubber), Butylrubber (HR), and Halobutylrubber.

[0112] Preferably, the styrene-butadiene copolymer (SBR) comprises a solution- polymerized styrene-butadiene rubber (SSBR), an emulsion-polymerized styrene-butadiene rubber (ESBR), or a mixture thereof.

[0113] Very preferably, the diene-based rubber polymer being different from (b) comprises natural polyisoprene (NR) and / or polybutadiene (BR), most preferably natural polyisoprene (NR).

[0114] (d) further ingredients:

[0115] The sulfur-crosslinkable rubber composition according to the invention preferably comprises further compounds (i.e. in addition to (a), (b), and (c) as defined throughout the text).

[0116] Preferred is a sulfur-crosslinkable rubber composition according to the invention further comprising each individually one or more of i) an aging stabilizer (also known as antioxidants), preferably comprising para-phenylendiamine and / or dihydroquinoline; more preferably selected from the group consisting of N-phenyl-N’-(1 ,3- dimethylbutyl)-p-phenylenediamine (6PPD), N,N‘-diphenyl-p- phenylenediamine (DPPD), N-(1-phenylethyl)-N’-phenyl-p- phenylenediamine (SPPD), N,N‘-ditolyl-p-phenylenediamine (DTPD), N-(1 ,4-dimethylpentyl)-N'-phenyl-p-phenylenediamine (7PPD), N- isopropyl-N’-phenyl-p-phenylenediamine (IPPD), und 2,2,4-trimethyl- 1 ,2-dihydroquinoline (TMQ); ii) an activator, preferably comprising a zinc compound (including zinc complexes) and / or fatty acids; very preferably comprising zinc oxide, stearic acid and / or zinc ethylhexanoate; iii) a coupling agent (also known as bonding compound) for binding filler materials (particularly for carbon black and silica); preferably comprising S-(3-aminopropyl)-thiosulfuric acid, metal salts thereof (particularly for binding carbon black) and / or silane-coupling agents (particularly for binding silica); iv) a wax, preferably an ozone protection wax; v) a resin, preferably a tackifying resin, which is not a softener resin; vi) a masticating aid, preferably comprising 2,2’- Dibenzamido diphenyl disulfide (DBD); vii) a processing aid, preferably comprising a fatty acid ester; viii) a softener (also known as plasticizer), preferably comprising oils and / or resins (preferably oils); ix) an accelerator, preferably selected from the group consisting of thiazole compounds, mercapto compounds, sulfenamide compounds, thiocarbamate compounds, thiuram compounds, thiophosphate compounds, thiourea compounds, xanthate compounds, and guanidine compounds; and / or x) sulfur and sulfur-donor compounds, preferably thiuram disulfides and / or thiuram tetrasulfides.

[0117] Generally preferred is a sulfur-crosslinkable rubber composition according to the invention comprising said further ingredients according to (d) in a total amount ranging from 1 to 300 phr, preferably from 2 to 200 phr, more preferably from 3 to 100 phr, even more preferably from 4 to 80 phr, most preferably from 5 to 60 phr. The total amount in this context refers to the sum of i) to x).

[0118] Preferably, the aging stabilizer according to i) above is present in a total amount ranging from 0.1 phr 15 phr, preferably from 0.5 to 10 phr, most preferably from 1 to 5 phr.

[0119] Preferably, the activator according to ii) above is present in a total amount ranging from 0.1 phr 20 phr, preferably from 0.5 to 15 phr, most preferably from 1 to 10 phr.

[0120] There is no particular limitation to said silane-coupling agents (see iii) above). However, preferred silane-coupling agents comprise bifunctional organo silanes, wherein the silicon atom is bound to an alkyl, alkoxy, cycloalkoxy and / or phenoxy group. Preferably, the silane-coupling agent additionally comprises another functional group, preferably a SH group (i.e. it is a mercaptosilane).

[0121] More preferred silane-coupling agents comprise 3-mercaptopropyl triethoxy silane, 3-thiocyanato-propyl trimethoxy silane, 3,3‘- bis(triethoxysilylpropyl) polysulfides having 2 to 8 sulfur atoms (very preferred 3,3‘-bis(triethoxysilylpropyl) tetrasulfide (TESPT) and / or its disulfide (TESPD)) and / or mixtures of sulfides having different amounts of sulfur atoms. Very preferred is TESPT and TESPD.

[0122] Preferred silane-coupling agents comprise, additionally or alternatively, also those disclosed in WO 2008 / 083241 A1 , WO 2008 / 083242 A1 , WO 2008 / 083243 A1 and WO 2008 / 083244 A1 . Preferably, the total amount of the coupling agent according to iii) is ranging from 1 to 50 phf (parts per hundred parts of filler by weight), preferably from 2 to 40 phf, more preferably from 3 to 30 phf, even more preferably from 4 to 20 phf, most preferably from 5 to 15 phf. This most preferably applies if silane-coupling agents are the only coupling agents in the sulfur-crosslinkable rubber composition.

[0123] Preferably, the wax according to iv) above is present in a total amount ranging from 0.1 phr 15 phr, preferably from 0.5 to 10 phr, most preferably from 1 to 5 phr.

[0124] Regarding the softener according to viii) above, preferred oils comprise mineral oil and / or vegetable oil. A preferred vegetable oil comprises canola oil. Preferred mineral oils comprise mild extraction solvate (MES), destillated aromatic extracts (DAE), residual aromatic extract (RAE), treated distillate aromatic extract (TDAE), and Rubber-to-Liquid-oils (RTL oils).

[0125] Preferably, the softener according to viii) above is present in a total amount ranging from 1 phr 60 phr, preferably from 5 to 50 phr, most preferably from 10 to 40 phr.

[0126] Regarding the accelerator according to ix) above, preferred is a sulfenamide compound. Very preferably, the accelerator comprises N- cyclohexyl-2-benzothiazolsufenamide (CBS), N,N- dicyclohexylbenzothiazol-2-sulfenamide (DCBS), Benzothiazole-2- sulfenmorpholide (MBS), N-tert-Butyl-2-benzothiazolesulfenamide (TBBS) und Diphenylguanidin (DPG).

[0127] Preferably, the accelerator according to ix) above is present in a total amount ranging from 0.1 phr 15 phr, preferably from 0.25 to 10 phr, most preferably from 0.5 to 5 phr.

[0128] There is no particular limitation to said sulfur and sulfur-donor compounds according to x) above as long as they provide sulfur. In some cases, sulfur-donor compounds overlap with accelerator compounds of being from the same compound class. Preferred sulfur-donor compounds are selected from the group consisting of thiuram disulfides, thiuram tetrasulfides, dithiophosphates, and polysulfides. Preferred thiuram disulfides comprise tetrabenzylthiuramdisulfide (TBzTD), tetramethylthiuramdisulfide (TMTD) and / or tetraethylthiuramdisulfide (TETD). A preferred thiuram tetrasulfide comprises dipentamethylenethiuram tetrasulfide (DPTT). Preferred dithiophosphates comprise bis(diisopropyl)thiophosphoryl disulfide (DIPDIS), zinc dichloryldithiophosphate, and / or zinc alkyldithiophosphate. Preferred polysulfides comprise bis(O,O-2-ethylhexyl-thiophosphoryl)polysulfide, diarylpolysulfides and / or dialkylpolysulfides.

[0129] Preferably, the sulfur and sulfur-donor compound according to x) above is present in a total amount ranging from 0.1 phr 15 phr, preferably from 0.25 to 10 phr, most preferably from 0.5 to 5 phr.

[0130] The presence of further compounds such as ix) the accelerator and x) the sulfur and sulfur-donor compounds is required shortly before the vulcanization of the sulfur-crosslinkable rubber composition in order to obtain a sulfur-vulcanized rubber composition.

[0131] The sulfur-vulcanized rubber composition:

[0132] The present invention also relates to a sulfur-vulcanized rubber composition obtainable through sulfur-vulcanization of a sulfur- crosslinkable rubber composition according to the invention, preferably a sulfur-crosslinkable rubber composition of the present invention as herein described as being preferred.

[0133] Preferably, the aforementioned regarding the sulfur-crosslinkable rubber composition according to the present invention, including its preferred, more preferred, most preferred, etc. embodiments and features, applies mutatis mutandis also to the sulfur-vulcanized rubber composition of the present invention. It is essential that the vulcanization of the sulfur-crosslinkable rubber composition is conducted in the presence of sulfur and / or sulfur-donor compounds, and preferably, also vulcanization accelerators. As already mentioned above, in some case accelerators are at the same time sulfur- donor compounds.

[0134] In order to better control the vulcanization, in some cases vulcanization retarders are utilized.

[0135] Typically, all chemical compounds affecting the vulcanization, i.e. sulfur, sulfur-donor compounds, accelerators, etc., are also known as vulcanization system or cure / curing package. Commonly, they are added under mixing in a subsequent step to a pre-mixed sulfur-crosslinkable rubber composition followed by further optional process steps. Vulcanization itself is typically conducted at elevated temperatures, wherein suitable process parameters are well established in the industry.

[0136] In view of the above, the present text also relates to the use of a sulfur- crosslinkable rubber composition according to the invention for obtaining a sulfur-vulcanized rubber composition through vulcanization.

[0137] Furthermore, the present text also refers to a process for preparing a sulfur-crosslinkable rubber composition or a sulfur-vulcanized rubber composition, each according to the present invention, comprising the steps:

[0138] (A) providing or producing a filler component, preferably as described throughout the text, most preferably as described as being preferred;

[0139] (B) providing or producing at least one modified conjugated diene- based polymer as described throughout the text, most preferably as described as being preferred;

[0140] (C) optionally providing (c) a diene-based rubber polymer being different from the polymer provided and produced, respectively, in step (B), preferably as described as being preferred throughout the text,

[0141] (d) further ingredients as described throughout the text, most preferably as described as being preferred;

[0142] (D) mixing in one or more than one step the filler component from step (A), the at least one modified conjugated diene-based polymer from step (B), and what is optionally provided in step (C), such that the sulfur-crosslinkable rubber composition or the sulfur-vulcanized rubber composition results.

[0143] Regarding this process of the present invention, the aforementioned regarding the sulfur-crosslinkable rubber composition of the present invention and the sulfur-vulcanized rubber composition of the present invention preferably also applies mutatis mutandis to this process of the present invention.

[0144] In the above-mentioned process, step (D) is preferably carried out in more than one step (preferably in several individual mixing steps) in order to mix all what is provided in steps (A), (B), and optionally in (C).

[0145] Furthermore, in the above-mentioned process, the presence of a vulcanization system or cure / curing package determines whether the sulfur-crosslinkable rubber composition or the sulfur-vulcanized rubber composition is obtained.

[0146] The present invention also relates to further products obtained from the sulfur-vulcanized rubber composition. Therefore, the present invention also refers to a rubber product comprising the sulfur-vulcanized rubber composition according to the present invention, most preferably a sulfur- vulcanized rubber composition of the present invention as described as being preferred throughout the text. Preferably, the afore-mentioned regarding the sulfur-vulcanized rubber composition applies also mutatis mutandis to the rubber product of the present invention.

[0147] Preferably, the sulfur-vulcanized rubber composition according to the present invention is contained in the rubber product, preferably in the entire product or at least in one part of the product.

[0148] In some cases, preferred is a rubber product of the present invention being a technical rubber product, preferably selected from the group consisting of bellows, belts (preferably conveyor belts and breaker belts), air springs, and shoe soles.

[0149] The present invention also refers to a tire, preferably a vehicle tire, most preferably a pneumatic vehicle tire, comprising the rubber product according to the present invention in at least one part of said tire.

[0150] The aforementioned regarding the sulfur-crosslinkable rubber composition of the present invention and the sulfur-vulcanized rubber composition of the present invention very preferably also applies mutatis mutandis to the tire of the present invention.

[0151] As mentioned, preferably, the vehicle tire is a pneumatic vehicle tire. However, in some cases, the vehicle tire is preferably a solid rubber tire.

[0152] Generally, in the context of the present invention, there is not restriction regarding the type of vehicle. Preferred is a vehicle tire selected from the group consisting of truck tires, passenger car tires, van tires, bicycle tires, commercial vehicle tires, and special vehicle tires.

[0153] The present text also relates to a use of at least one modified conjugated diene-based polymer as described throughout the present text, preferably as described as being preferred, in a sulfur-crosslinkable rubber composition for decreasing rolling resistance of a vehicle tire produced from the sulfur-crosslinkable rubber composition, preferably in a sulfur- crosslinkable rubber composition according to the present invention, preferably as described as being preferred throughout the present text.

[0154] Preferably, the afore-mentioned regarding the sulfur-crosslinkable rubber composition applies also mutatis mutandis to this use.

[0155] Hereinafter, the invention is described in more detail by means of experiments.

[0156] A) Synthesis of modified conjugated diene-based polymers:

[0157] Comparative Example 1

[0158] To a nitrogen-substituted autoclave reactor (capacity: 5 L), cyclohexane (2,500 g), 2,2di(tetrahydrofurfuryl)propane (0.8644 mmol) serving as a vinyl content adjusting agent (a randomizer), piperidine (4.331 mmol) serving as an initiation terminal-modifier, and styrene (50 g) and 1 ,3-butadiene (400 g) serving as monomers were added. The temperature of the contents of the reactor was adjusted to 20°C, and n-butyllithium (5.62 mmol) serving as a polymerization initiator was added to the reactor, to thereby initiate polymerization. The polymerization temperature was elevated from room temperature to 75°C over 25 minutes.

[0159] After the percent conversion of polymerization reached 99% (i.e., 25 minutes after start of polymerization), 1 ,3-butadiene (50 g) was further added over 5 minutes.

[0160] Subsequently, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane (an amino hydrocarbyl moiety with a tertiary nitrogen atom; may also be referred to as "N-Si-1" in the examples) (4.322 mmol) was added, and the mixture was caused to react for 15 minutes.

[0161] To the thus-obtained polymer solution, 2,6-di-tert-butyl-p-cresol (4.40 g) was added. Then, solvent was removed through steam stripping, and the resultant matter was dried by means of a heat roller whose temperature was controlled at 110°C, to thereby yield modified conjugated diene-based polymer A-1 (see Table 1 ).

[0162] Comparative Examples 2 to 5, and Examples 1 to 17, 19, and 20

[0163] The procedures of polymerization, solvent removal, and drying conducted in Comparative Example 1 were repeated, except that the type and amounts of the reagents employed were changed to the values shown in Table 1 , to thereby yield modified conjugated diene-based polymers A-2 to A-5, A-9 to A-25, A-27, and A-28.

[0164] Comparative Example 6

[0165] The procedures of polymerization, solvent removal, and drying conducted in Comparative Example 4 were repeated, except that reaction was performed for 15 minutes in the presence of ethylene sulfide; n-octanoyl chloride (4.322 mmol) was added before addition of 2,6-di-tert-butyl-p- cresol (4.40 g); and reaction was further performed for 10 minutes, to thereby yield modified conjugated diene-based polymer A-6.

[0166] Comparative Example 7

[0167] The procedures of polymerization, solvent removal, and drying conducted in Comparative Example 1 were repeated, except that 1 -(3- (dimethyl(tertbutoxy)silyl)propyl)piperazine (a piperazine moiety; may also be referred to as "Si-N-1 " in the examples) (4.331 mmol) and divinylbenzene (2.161 mmol) were used instead of piperidine and N-Si-1 , respectively, to thereby yield modified conjugated diene-based polymer A-7.

[0168] Comparative Example 8

[0169] To a nitrogen-substituted autoclave reactor (capacity: 5 L), cyclohexane (2,500 g), 2,2di(tetrahydrofurfuryl)propane (0.8644 mmol) serving as a vinyl content adjusting agent (a randomizer), and styrene (50 g) and 1 ,3- butadiene (400 g) serving as monomers were added. The temperature of the contents of the reactor was adjusted to 20°C. Separately, by use of a nitrogen-substituted pressure bottle (100 mL), n-butyllithium (11.24 mmol) and divinylbenzene (5.62 mmol) were reacted in cyclohexane (50 g), to thereby prepare an initiator solution. The initiator solution was added to the autoclave reactor, to thereby initiate polymerization. The polymerization temperature was elevated from room temperature to 75°C during about 25 minutes.

[0170] After the percent conversion of polymerization reached 99% (i.e., 25 minutes after start of polymerization), 1 ,3-butadiene (50 g) was further added over 5 minutes. Subsequently, ethylene sulfide (8.644 mmol) was added, and the mixture was caused to react for 15 minutes.

[0171] To the thus-obtained polymer solution, 2,6-di-tert-butyl-p-cresol (4.40 g) was added. Then, solvent was removed through steam stripping, and the resultant matter was dried by means of a heat roller whose temperature was controlled at 110°C, to thereby yield modified conjugated diene-based polymer A-8.

[0172] Example 18

[0173] The procedures of polymerization, solvent removal, and drying conducted in Example 1 were repeated, except that reaction was performed for 15 minutes in the presence of ethylene sulfide; n-octanoyl chloride (4.322 mmol) was added before addition of 2,6-di-tert-butyl-p-cresol (4.40 g); and reaction was further performed for 10 minutes, to thereby yield modified conjugated diene-based polymer A-26.

[0174] Tables 1 and 2 show physical properties of modified conjugated diene- based polymers A-1 to A-28 obtained after removal of solvent. Table 1 (A1-A15) and Table 2 (A16-A28)

[0175]

[0176] Details of the compounds listed in Tables 1 and 2 are as follows.

[0177] Initiation terminal-modifiers:

[0178] Si-N-1 denotes 1 -(3-(Dimethyl(tert-butoxy)silyl)propyl)piperazine (a piperazine moiety in the context of the present invention);

[0179] AI-200CE2 denotes a reaction product of 3-(dimethylamino)propyllithium with isoprene [ratio of reaction: isoprene / 3-(dimethylamino)propyllithium = 2 / 1 (mole ratio)] (an amino hydrocarbyl moiety with a tertiary nitrogen atom, specifically a N,N-(dialkyl)aminohydrocarbon moiety with one or more than one double bond), product of FMC

[0180] Termination terminal-modifiers:

[0181] N-Si-1 denotes N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane (an amino hydrocarbyl moiety with a tertiary nitrogen atom, specifically a N,N- bis(silyl)aminoalkyl-silane moiety)

[0182] S-Si-1 denotes a compound represented by the following formula (S-Si-1 ; a dialkyl tin(IV) bis(alkoxysilyl alkyl sulfide))

[0183] S-Si-1

[0184] Example 21

[0185] Into a nitrogen-substituted autoclave reactor (capacity: 50 L) (i.e., a first- stage reactor), there were continuously charged 1 ,3-butadiene (26.6 g / minute) and styrene (2.95 g / minute) serving as monomers; cyclohexane (180.2 g / minute) serving as a solvent; tetrahydrofuran (0.4 g / minute) serving as a vinyl content adjusting agent (a randomizer); and a mixture (mole ratio: 1 / 1 ) of n-butyllithium (serving as a polymerization initiator) and Si-N-1 (serving as an initiation terminal-modifier) (0.25 mmol / minute) at the abovespecified feed rates. The temperature inside the reactor was controlled to 75°C.

[0186] The polymer solution obtained in the first-stage reactor was continuously discharged at a rate of 210.2 g / minute. Ethylene sulfide was added to the discharged polymer solution at a rate of 0.20 mmol / minute, and the mixture was continuously fed into a second-stage reactor, where the mixture was caused to react. At the outlet of the second-stage reactor, di-tert-butyl-p- cresol was added so that the amount thereof was adjusted to 0.88 parts by mass to 100 parts by mass of the polymer. The thus-obtained polymer solution was subjected to steam stripping for removal of the solvent, and the resultant matter was dried by means of a heat roller whose temperature was controlled at 110°C, to thereby yield modified conjugated diene-based polymer A-29. Physical properties of modified conjugated diene-based polymer A-29 were as follows.

[0187] Bound styrene content: 10%, vinyl group content: 39%, Mw: 960,000, Mw / Mn: 1.6, nitrogen content: 68 ppm, and sulfur content: 133 ppm.

[0188] B) Production of sulfur-crosslinkable rubber compositions:

[0189] Comparative Examples 1 to 8 and Examples 1 to 21

[0190] According to formulations shown in Tables 3 and 4, components (ingredients) were blended, and each mixture was melt-kneaded, to thereby produce a polymer composition of interest. Melt-kneading was carried out in the following manner.

[0191] A first-stage kneading operation was performed by use of a batch-type mixer equipped with a temperature-controller (Labo Plastomill, product of Toyo Seiki Seisaku-sho, Ltd.). The kneading temperature was controlled to 100°C, and each modified conjugated diene-based polymer, polybutadiene rubber (BR), an extender oil, silica, carbon black, a silane coupling agent, stearic acid, an antioxidant, and zinc oxide were kneaded at a rotation speed of 60 rpm for 4 minutes.

[0192] Next, second-stage kneading was carried out. The kneaded product obtained by the first-stage kneading operation was cooled to room temperature. A vulcanization accelerator and sulfur were added to the cooled product. The resultant mixture was fed into the mixer. While the kneading temperature was controlled to 70°C, the mixture was kneaded at a rotation speed of 60 rpm for 1.5 minutes, to thereby yield polymer compositions (Q-1 to Q-29). In all cases, the temperature of the kneaded product discharged by the mixer was 100°C or lower. Subsequently, each of the produced compositions was molded with vulcanization at 160°C for a specific time by means of a vulcanization press machine, to thereby produce a sulfur-vulcanized rubber composition and to obtain respective specimens. These specimens were assessed further in terms of their physical properties. Tables 3 and 4 show the results.

[0193] Examples 22 and 23 as well as Comparative Examples CE9 to CE14

[0194] Examples 22 and 23 as well as Comparative Examples CE9 to CE14 (Table 5) were mixed similar as described above and according to a standard industry procedure, in which all the constituents apart from the vulcanization system (sulfur and vulcanization-influencing compounds) were first mixed in the first stage (base-mixing stage). By addition of the vulcanization system in the second stage (ready-mixing stage), the finished mixture was produced, with mixing at 90 to 120° C.

[0195] The respective compositions were used to produce specimens by vulcanization after approximately 10 minutes for carbon black-containing compositions and approximately 14 minutes for silica-containing compositions under pressure at 160 °C. These specimens were used to determine physical properties as mentioned and summarized in Table 6.

[0196] Rolling resistance (3% tan delta at 50°C; Tables 3 and 4) The ratio (tan delta at 50°C); i.e., loss modulus GVstorage modulus G', of each vulcanized rubber sample was determined by means of a shear-type dynamic spectrometer (product of TA Instruments) at an angular velocity of 100 rad / second and 50°C under a shear strain of 3%. The measurement was represented by an index with respect to the rolling resistance of the sample of Comparative Example 1 as 100. The greater the value, the more suitable (i.e., smaller) the rolling resistance and fuel efficiency.

[0197] Rolling resistance (tan delta at 70°C; Table 6)

[0198] Rolling resistance in this case refers to the loss factor tangens delta max at 70°C as maximum value of the strain sweep from dynamic-mechanic measurement according to DIN 53513.

[0199] Strength ((TBxEB) / 2; Tables 3 and 4)

[0200] A vulcanized rubber sample was subjected to a tensile test in accordance with JIS K6251 :2010. In the test, the test sample was a dumbbell No. 3 sample, and tensile stress at break (TB, MPa) and elongation at break (EB, %) were measured at room temperature. A half value of the tensile product (=(TBxEB)) was employed to provide a strength. The measurement was represented by an index with respect to the strength of the sample of Comparative Example 1 as 100. The greater the value, the higher the strength.

[0201] Shore A hardness (Table 6)

[0202] Shore A hardness was determined at room temperature by means of a Durometer based on DIN 53505.

[0203] Rebound resilience (Table 6)

[0204] The rebound resilience was determined at 70°C according to DIN 53 512 (resilience 70°C).

[0205] Wear resistance (DIN abrasion; Tables 3 and 4) Wear resistance of a vulcanized rubber sample was determined by means of a DIN abrasion tester (product of Toyo Seiki Seisaku-sho, Ltd.) at a load of 10 N and 25°C in accordance with JIS K6264. The measurement was represented by an index with respect to the wear resistance of the sample of Comparative Example 1 as 100. The greater the value, the more excellent the wear resistance.

[0206] Abrasion as shown in Table 6 was determined at room temperature according to DIN / ISO 4649. The lower the value, the better the abrasion.

[0207] Table 3 (Q1-Q14) and Table 4 (Q15-Q29)

[0208]

[0209] Details of the compounds listed in Tables 3 to 4 are as follows.

[0210] *1 ) Tradename "BR01 ," ENEOS Materials Corporation

[0211] *2) Tradename "ZEOSIL 1165MP," product of Solvay

[0212] *3) Tradename "DIABLACK N330," product of Mitsubish Chemical *4) Tradename "Si75," product of Evonik

[0213] *5) Process oil, tradename "T-DAE," product of ENEOS

[0214] *6) Ozonone 6C, product of Seiko Chemical Co., Ltd.

[0215] *7) Tradename "Nocceler D," product of Ouchi Sinko Chemical Industrial Co., Ltd. *8) Tradename "Nocceler CZ-G," product of Ouchi Sinko Chemical Industrial Co., Ltd.

[0216] As is clear from Tables 1 to 4, cross-linked bodies exhibiting rolling resistance, wear resistance, and strength in a well-balanced manner were able to be produced from any of the modified conjugated diene-based polymers obtained in Examples 1 to 21 .

[0217] Further experimental compositions were tested as summarized in Table 5 below. Physical properties thereof are summarized in Table 6 below.

[0218] Table 5; “CE” denotes “Comparative Example”; “E” denotes “Example”:

[0219] Details of the compounds listed in Table 5 are as follows.

[0220] *1Natural Rubber (NR), TSR type

[0221] #2SBR unfunctionalized styrol-butadiene copolymer (SBR) *3N220, Orion

[0222] *4VN3, Evonik

[0223] *5TESPD, Evonik

[0224] *6combination of 6PPD, TMQ, and DTPD for CE1 to CE3 and E22; 6 PPD for CE4 to CE6 and E23 *7TDAE

[0225] *8TBBS for CE1 to CE3 and E22; a combination of DPG and CBS for CE4 to CE6 and E23

[0226] Table 6, physical properties of compositions according to Table 5

[0227] According to Table 6, all examples clearly show that a comparatively good Shore A hardness is not compromised by utilizing the modified conjugated diene-based polymers. Comparing Example E22 with its respective comparative examples CE9 to CE11 , a very narrow range from 62 to 64 ShA is maintained. A correspondingly similar result is obtained for E23 compared to CE12 to CE14 (ranging from 63 to 68 ShA).

[0228] In contrast, the resilience at 70°C is significantly increased in each set of examples. A maximum of 58% is obtained for E22 compared to lower values obtained with comparative examples CE9 to CE11 (only ranging from 48 to 55%). A similar pattern can be seen for E23 (54%) compared to CE12 to CE14 (only ranging from 43 to 51 %).

[0229] Furthermore, tangens delta at 70°C is also improved (i.e. reduced) significantly. A minimum of 0.108 is obtained for E22 compared to significantly higher values obtained with comparative examples CE9 to

[0230] CE11 (only ranging from 0.124 to 0.148). Again, a similar pattern can be seen for E23 (0.115) compared to CE12 to CE14 (only ranging from 0.141 to 0.166). A combination of increased resilience and reduced tangens delta impressively shows that a significantly improved rolling resistance is obtained with the compositions according to the invention.

[0231] At the same time, abrasion is either also improved (see E22 compared to CE9 to CE11 ) or is at least not significantly compromised (see E23 compared to CE12 to CE14).

[0232] Furthermore, example E22 has been reproduced with the exception that modified conjugated diene-based polymer A-15 was used instead of A-9, resulting in an example “E22a”. The following was obtained for E22a: Shore A hardness: 64; Resilience (70°C): 60, Tan delta (70°C): 0.100; and Abrasion (RT): 71 .

[0233] Likewise, example E23 has been reproduced with the exception that modified conjugated diene-based polymer A-22 was used instead of A-9 resulting in example “E23a”. The following was obtained for E23a: Shore A hardness: 68; Resilience (70°C): 57, Tan delta (70°C): 0.103; and Abrasion (RT): 70.

Claims

Claims1. A sulfur-crosslinkable rubber composition comprising(a) a filler component in a total amount ranging from 1 to 350 phr, and(b) at least one modified conjugated diene-based polymer, which has one or more than one polymer chain each comprising a structural unit derived from a conjugated diene compound, each polymer chain having its terminal ends modified by a functional group either being a nitrogen-containing functional group or a sulfur- containing functional group, with the proviso thatA) - at least one terminal end of the terminal ends is modified by a nitrogen-containing functional group and at least another terminal end of the terminal ends is modified by a sulfur-containing functional group, and- in each polymer chain having two corresponding terminal ends, one end is modified by a nitrogen-containing functional group and the other end is modified by a sulfur- containing functional group; orB) - two, three or more than three polymer chains of the more than one polymer chain are bound to each other by means of either a nitrogen-containing functional group or a sulfur- containing functional group, each functioning as a linker group, and- the functional groups modifying the terminal ends of the two, three or more than three polymer chains are (i) sulfur-containing functional groups if the linker group is a nitrogencontaining functional group or (ii) nitrogen-containing functional groups if the linker group is a sulfur-containing functional group.

2. The sulfur-crosslinkable rubber composition according to claim 1 , wherein the filler component comprises as filler material silica and / or carbon black.

3. The sulfur-crosslinkable rubber composition according to claim 1 or 2, comprising the filler component in a total amount ranging from 10 to 300 phr, preferably from 15 to 260 phr, more preferably from 20 to 220 phr, even more preferably from 25 to 180 phr.

4. The sulfur-crosslinkable rubber composition according to any one of claims 1 to 3, wherein- in the at least one modified conjugated diene-based polymer the conjugated diene compound comprises butadiene compounds and / or styrene compounds, and / or- the at least one modified conjugated diene-based polymer has a styrene content ranging from 0 to 50 wt.-%, based on the total weight of the polymer, preferably from 5 to 50 wt.-%, more preferably from 5 to 40 wt.- %, even more preferably from 6 to 30 wt.-%, yet even more preferably from 6 to 20 wt.-%, most preferably from 7 to 15 wt.-%, and / or- the at least one modified conjugated diene-based polymer has a vinyl content ranging from 10 to 80 wt.-%, based on the total weight of butadiene compounds, preferably from 15 to 65 wt.-%, more preferably from 20 to 60 wt.-%, even more preferably from 25 to 55 wt.-%, most preferably from 30 to 50 wt.-%.

5. The sulfur-crosslinkable rubber composition according to anyone of claims 1 to 4, wherein in the at least one modified conjugated diene-based polymer the nitrogen-containing functional group comprises-a N-hetero-cycloalkyl moiety having one, two or three ring-nitrogen atoms; preferably as a six-membered ring thereof; or- an amino hydrocarbon moiety with a tertiary nitrogen atom.

6. The sulfur-crosslinkable rubber composition according to claim 5, wherein the N-hetero-cycloalkyl moiety having one, two or three ring-nitrogen atoms, comprises- a piperidine moiety,- a diazinane moiety, preferably a piperazine moiety, more preferably a 1 -silyl-piperazine moiety or a 1 -silylalkylpiperazine moiety, even more preferably a 1 -(trialkylsilyl)piperazine moiety or a 1 -(3-(dialkyl(tert-alkoxy)silyl)propyl)piperazine moiety, most preferably a 1 -(trimethylsilyl)piperazine moiety or a 1 -(3-(dimethyl(tert-butoxy)silyl)propyl)piperazine moiety; and / or- a triazinane moiety, preferably a 1 ,3,5-triazinane moiety.

7. The sulfur-crosslinkable rubber composition according to claim 5, wherein the amino hydrocarbon moiety with a tertiary nitrogen atom comprises- a N,N-(dialkyl)aminohydrocarbon moiety with one or more than one double bond, preferably a reaction compound of 3-(dimethylamino)propyl lithium with isoprene; and / or- a N,N-bis(silyl)aminoalkyl-silane moiety, preferably a N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane moiety.

8. The sulfur-crosslinkable rubber composition according to any one of claims 1 to 7, wherein in the at least one modified conjugated diene-based polymer the sulfur-containing functional group is selected from the group consisting of- a thiirane moiety;- a carbon disulfide moiety;- a hydrocarbylthiol moiety, preferably an alkene thiol moiety, most preferably a propene thiol moiety;- a thioether moiety, preferably an aromatic thioether moiety, most preferably a phenyl vinyl sulfide moiety;- a thioester moiety;- a dithioester moiety,preferably an aromatic dithioester moiety, most preferably a cumyl dithiobenzoate moiety;- a thioketone moiety, preferably an aromatic thioketone moiety, most preferably a bis(dimethylamino)thiobenzophenone moiety, or preferably a branched aliphatic thioketone moiety, most preferably a di-te / t-butyl thioketone moiety;- a dithiane moiety, preferably an alkyl dithiane moiety, most preferably a methyl-1 ,3-dithiane moiety;- a dithiolane moiety;- a thiophene moiety; and / or- a dialkyl tin(IV) disulfide moiety or dialkyl silyl disulfide moiety, each comprising an alkoxy silyl group, preferably a dialkyl tin(IV) bis(alkoxysilyl alkyl sulfide) moiety.

9. The sulfur-crosslinkable rubber composition according to anyone of claims 1 to 8, wherein the at least one modified conjugated diene-based polymer has a sulfur content in a range from 50 to 800 ppm, based on the total weight of said polymer, preferably from 65 to 675 ppm, more preferably from 80 to 550 ppm, even more preferably from 95 to 425 ppm, yet even more preferably from 110 to 300 ppm, most preferably from 125 to 250.

10. The sulfur-crosslinkable rubber composition according to any one of claims claim 1 to 9, wherein the at least one modified conjugated diene- based polymer has a nitrogen content in a range from 25 to 500 ppm, based on the total weight of said polymer, preferably from 50 to 420 ppm.11 . The sulfur-crosslinkable rubber composition according to any one of claims 1 to 10, wherein the at least one modified conjugated diene-based polymer has a weight average molecular weight Mwin a range from 50,000 to 2,000,000 g / mol, preferably from 70,000 to 1 ,500,000 g / mol, more preferably from 90,000 to 1 ,000,000 g / mol, even more preferably from110,000 to 750,000 g / mol, yet even more preferably from 130,000 to 500,000 g / mol, most preferably from 130,000 to 300,000 g / mol.

12. The sulfur-crosslinkable rubber composition according to any one of claims 1 to 11 , further comprising(c) a diene-based rubber polymer being different from (b), preferably selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), polybutadiene (BR; butadiene rubber), styrene-butadiene copolymer (SBR, styrene-butadiene rubber), Butylrubber (HR), and Halobutylrubber.

13. A sulfur-vulcanized rubber composition obtainable through sulfur- vulcanization of the sulfur-crosslinkable rubber composition according to any one of claims 1 to 12.

14. A rubber product comprising the sulfur-vulcanized rubber composition according to claim 13.

15. A tire, preferably a vehicle tire, most preferably a pneumatic vehicle tire, comprising the rubber product according to claim 14 in at least one part of said tire.

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