A rubber composition for use in the manufacture of vehicle tires

Abstract

The present invention provides a diene rubber-silica compound comprising a diene rubber matrix having dispersed therein a silica filler, the silica filler being reversibly bonded to the diene rubber matrix via dynamic imine bonds. In particular, the present invention provides such a compound, in which the diene rubber is a styrene-butadiene rubber. Such a compound can be vulcanized and is suitable for the manufacture of vehicle tire components, such as tire treads.

Description

Technical Field

[0001] The present invention relates to a recyclable diene rubber compound, a method for producing the same, and their use in the production of vehicle tires and vehicle tire parts. In particular, the present invention relates to the use of said compound for producing a tire tread.

[0002] More specifically, the present invention relates to a silica-reinforced diene rubber compound in which a reversible interaction between a silica filler and a diene rubber is brought about by a dynamic imine bond. This reversible interaction improves the mechanical properties of the rubber compound and at the same time advantageously improves the recyclability of the rubber compound.

Background Art

[0003] Diene rubbers such as natural rubber, isoprene rubber and butadiene rubber contain repeating units derived from diolefins having conjugated carbon-carbon double bonds. The properties of synthetic diene rubbers can be specifically adjusted by copolymerization of diolefin monomers with other monomers, and they are used in a wide range of applications.

[0004] Styrene-butadiene rubber (referred to as "SBR" in this specification) is an example of butadiene rubber produced by the polymerization of styrene and butadiene. The ratio of styrene to butadiene affects the properties of the polymer, and various types of SBR are used as components of automotive tires, especially in parts such as tire treads. When used in the production of tire treads, SBR is usually crosslinked using a sulfur vulcanization system. By using various reinforcing fillers such as silica and carbon black, its mechanical properties are improved. Carbon black was the first material commonly used as a filler, but recently silica has largely replaced the use of conventional carbon black in SBR-based compounds. The use of silica fillers improves rubber properties, particularly reducing rolling resistance and improving traction on wet surfaces. Other diene rubbers, including butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber (ENR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), isobutylene-isoprene rubber (IIR), styrene-isoprene-butadiene rubber (SIBR), and ethylene-propylene-diene rubber (EPDM), are also commonly used in the production of components in the automotive industry. Similar to SBR-based compounds, the mechanical properties of rubber compounds made from any diene rubber can be improved in the same way by incorporating reinforcing fillers such as silica.

[0005] When producing high-performance rubber compounds with the required mechanical properties, the dispersion of reinforcing fillers and the filler-rubber interaction are important. When polar silanol groups are present on the surface of silica, the silica becomes acidic and highly hygroscopic. This causes the aggregation of silica, which in turn leads to poor dispersion in the rubber matrix, resulting in an increase in the viscosity of the compound and a loss of reinforcing properties. Various treatments of silica have been proposed to adjust the surface chemistry of silica, such as the use of surface modifiers or silanes as "compatibilizers". Silane coupling agents such as bis(triethoxysilylpropyl)tetrasulfide (TESPT) and bis(3-triethoxysilylpropyl)disulfide (TESPD) are also used to form covalent bonds between silica and diene rubber chains, for example, the chains of SBR. These improve the dispersibility of the filler in the diene rubber matrix and strengthen the interaction between silica and rubber to reinforce the rubber compound.

[0006] Vehicle tires have a limited lifespan due to general wear and deterioration such as in tire treads, and can cause significant problems as waste. They occupy valuable space in landfills and usually do not biodegrade. Therefore, there is always a need to improve the sustainability of the rubber compounds used in tire manufacturing. The ability to recycle such materials and use them as a second raw material that can be mixed with other new raw materials has been the subject of much research. One of the most difficult types of tire materials to recycle is diene rubber filled with silica such as SBR-silica. This is because of the strong covalent bonds that exist between the rubber chains formed by the silane coupling agent and the silica filler. To recycle such materials, it is necessary to break these covalent bonds. If the covalent bonds remain, they can inhibit fluidity and compatibility and there is a possibility of co-crosslinking when the recycled material is mixed with other new polymers. Therefore, recycling is difficult and generally uneconomical.

[0007] Conventional diene rubbers reinforced with silica, such as SBR-silica compounds, have two types of covalent bonds. One is the sulfur crosslinking resulting from the vulcanization system used to cure the rubber. The other is the covalent bond between the diene rubber chain and silica due to the use of a silane coupling agent as described above. Since a great deal of energy is required to break these covalent bonds, the reuse of these rubbers as raw materials, such as SBR-silica compounds, is severely restricted by these covalent interactions.

[0008] Therefore, although silica-containing diene rubber compounds such as SBR-silica compounds have come to be preferably used in the manufacture of passenger car tires, there is a need for another method of bonding a silica filler to a diene rubber that can provide a rubber compound that maintains or improves the performance characteristics of the tire while improving recyclability.

Summary of the Invention

[0009] The inventors herein propose a reversible bonding system for silica-containing diene rubber compounds in which the silica filler is bonded to the diene rubber via a dynamic imine bond. It is proposed that this bonding system can effectively replace the covalent silane coupling of conventional diene rubber-silica compounds, thereby allowing the compound to be recycled more easily while maintaining the desired mechanical properties.

[0010] Specifically, the inventors propose a bond between a silica filler and a polymer chain of a diene rubber via a coupling agent that contains a dynamic imine bond in its backbone and is attached to both the surface of the silica and the polymer chain of the diene rubber. This dynamic imine bond is a "reversible" covalent bond. That is, since it can be disassembled and reassembled, it provides the desired reversibility to the bond between the silica and the diene rubber chain. This is useful for the recycling and reprocessing of diene rubber compounds. Without being bound by theory, the dynamic nature of the imine bond is thought to be able to effectively "reconnect" even if it is "cut" as a result of mechanical damage to the rubber compound during use. The breakage of the bond that can occur from minute cracks or fissures in the rubber compound can thus be reassembled without the need for external stimuli, and the desired mechanical properties of the compound are automatically restored. The exact temperature conditions for reassembly vary depending on the chemical structure of the components that form the dynamic imine bond. In some cases, reassembly may occur at room temperature. When higher temperatures are required to reassemble the bond, these are usually expected to occur during the use conditions. For example, the temperature rise of a rolling tire tread may assist the reassembly performance of the rubber compound.

[0011] The silica filler can be "pre-modified" (i.e., pre-prepared) by adding a coupling agent to its surface prior to dispersion into the diene rubber matrix. The coupling agent incorporates a dynamic imine bond and a functional moiety capable of directly or indirectly bonding to the polymer chain of the diene rubber during compounding and / or vulcanization to form a reversible bonding system. Alternatively, as part of the compounding and / or vulcanization process for manufacturing the rubber compound, the bonding system may be formed completely in situ. The in situ formation of the reversible bonding system involves the surface modification of the silica filler in situ and its linkage to the diene rubber chain.

[0012] Dynamic covalent bonds are covalent bonds that can be reversibly assembled and disassembled. That is, dynamic covalent bonds provide reversible chemical bonds. The dynamic imine bond formed between an aldehyde and a primary amine is an example of a dynamic covalent bond in which a dynamic equilibrium exists among the aldehyde, the amine, and the imine. A crosslinked network formed from dynamic imine bonds has been proposed for a silicone elastomer that can self-heal at high temperatures and can be recycled by hot pressing (for example, Zhao et al., Molecules, 2020, 25, 597 and Feng et al., Ind. Eng. Chem. Res., 2019, 58, 1212-1221). To date, there has been no suggestion that this type of bond can be used in composite materials where other components may interfere with the self-healing properties of the dynamic imine bond.

[0013] The inventors propose the use of dynamic imine bonds that introduce reversible interactions between silica fillers and diene rubber matrices to improve the recyclability of rubber compounds used in the manufacture of vehicle tires and vehicle tire components. They have found, contrary to expectations, that other components contained in such rubber compounds do not adversely affect the dynamic nature of the imine bond and its ability to disassemble and reassemble. Indeed, surprisingly, the inventors have found that the bonding of silica to diene rubber via dynamic imine bonds improves certain mechanical properties of the diene rubber compound compared to those known for use in the manufacture of tires using conventional silane coupling agents. In particular, the tensile strength of the rubber compound is improved compared to a rubber compound using the bifunctional silane coupling agent TESPD.

[0014] Accordingly, the present invention solves the problems associated with known rubber-silica compounds by providing a bonding system that not only retains and / or improves the main performance characteristics of rubber products but also enhances recyclability.

[0015] Accordingly, in one aspect, the present invention provides a diene rubber-silica compound comprising a diene rubber matrix in which silica fillers are dispersed, wherein the silica fillers are reversibly bonded to the diene rubber matrix via dynamic imine bonds.

[0016] In another aspect, the present invention provides a method for producing a diene rubber-silica compound as described herein, the method comprising bonding a silica filler to a diene rubber matrix via dynamic imine bonds.

[0017] In another aspect, the present invention provides a vulcanizable rubber composition comprising a diene rubber matrix in which silica fillers are dispersed, wherein the silica fillers are reversibly bonded to the diene rubber matrix via dynamic imine bonds.

[0018] In another aspect, the present invention provides a vulcanized rubber compound that is directly obtained, or can be obtained, by crosslinking a vulcanizable rubber composition as described herein.

[0019] In another aspect, the present invention provides a method for producing a vulcanized diene rubber-silica compound comprising a diene rubber matrix in which a silica dispersant reversibly bonded to the diene rubber matrix via dynamic imine bonds is dispersed, the method comprising the following steps: (i) a step of surface-modifying a silica filler by adding a coupling agent incorporating dynamic imine bonds and capable of forming a bond with a diene rubber matrix during compounding and / or vulcanization; (ii) a step of providing a vulcanizable rubber composition by compounding the obtained surface-modified silica filler with a diene rubber matrix; and (iii) a step of subjecting the vulcanizable rubber composition to vulcanization The method provided includes.

[0020] In another aspect, the present invention is a method for producing a vulcanized diene rubber-silica compound comprising a diene rubber matrix in which a silica dispersant reversibly bonded to the diene rubber matrix via a dynamic imine bond is dispersed, the method comprising the following steps: (i) adding a silica filler to the diene rubber matrix together with one or more compounds capable of reacting with the silica filler to provide a surface-modified silica filler incorporating a dynamic imine bond and having a coupling agent added thereto capable of forming a bond with the diene matrix during compounding and / or vulcanization; (ii) compounding the resulting composition to provide a vulcanizable rubber composition comprising the surface-modified silica filler; and (iii) subjecting the vulcanizable rubber composition to vulcanization. A method is provided which comprises the above.

[0021] In another aspect, the present invention provides a vulcanized diene rubber-silica compound obtainable directly or obtainable by the method described herein.

[0022] In another aspect, the present invention provides the use of the diene rubber-silica compound described herein as a component of a vehicle tire or in the manufacture of components of a vehicle tire.

[0023] In another aspect, the present invention provides a vehicle tire component made from the diene rubber-silica compound described herein.

[0024] In another aspect, the present invention provides a vehicle tire comprising the vehicle tire component described herein.

[0025] In another aspect, the present invention provides a method for recycling the diene rubber-silica compound described herein, the method comprising the step of devulcanizing the compound and optionally the step of recovering the diene rubber.

[0026] In another aspect, the present invention provides a silica filler that is surface - modified by the addition of a coupling agent capable of forming a bond with a diene rubber, and the coupling agent incorporates a dynamic imine bond.

[0027] In another aspect, the present invention provides a method for manufacturing the surface - modified silica filler described herein, the method including the step of chemically modifying silica by the addition of a coupling agent capable of forming a bond with a diene rubber, and the coupling agent incorporates a dynamic imine.

DETAILED DESCRIPTION OF THE INVENTION

[0028] In one aspect, the present invention relates to a diene rubber - silica compound comprising a diene rubber matrix in which a silica filler is dispersed, wherein the silica filler is reversibly bonded to the diene rubber matrix via a dynamic imine bond.

[0029] Unless otherwise specified, the terms "rubber compound" and "rubber composition" are used interchangeably herein and refer to a rubber blended or mixed (i.e., compounded) with various components or materials. "Diene rubber - silica compound" refers to a diene rubber mixed with a silica filler.

[0030] The present invention relates to both raw (i.e., before curing or vulcanizing) and cured or vulcanized diene rubber compounds and diene rubber compositions, i.e., after cross - linking or vulcanizing.

[0031] As used herein, the term "dienegum" refers to a rubber containing repeating units derived from at least one conjugated diolefin monomer. This includes homopolymers and copolymers having one or more additional units derived from monomers copolymerizable with the diolefin monomer. The repeating units have carbon-carbon double bonds that may be present in the polymer backbone and / or side chains. The dienegum may be natural rubber or synthetic rubber. Non-limiting examples of dienegum include butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber (ENR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), isobutylene-isoprene rubber (IIR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), and ethylene-propylene-diene rubber (EPDM).

[0032] In one embodiment, the dienegum for use in the present invention contains repeating units derived from butadiene. Examples of such rubbers include, but are not limited to, styrene-butadiene rubber (SBR) and butadiene rubber (BR). In a series of embodiments, the dienegum used in the present invention is SBR.

[0033] As used herein, the term "dynamic imine bond" refers to an imine bond (-N=CH-) that is in equilibrium with the corresponding aldehyde and primary amine in the presence of water. As will be appreciated, the nature of the aldehyde and primary amine, and thus the chemical structure of the adjacent groups in the resulting imine bond, will affect its dynamic nature. In the present invention, it is contemplated that any known dynamic imine bond may be used, which is typically formed by the reaction of an aromatic aldehyde or heteroaromatic aldehyde with a primary amine. For example, it may be formed by the reaction of an optionally substituted benzaldehyde with a primary amine, or by the reaction of an optionally substituted pyridinecarboxaldehyde with a primary amine. The resulting imine bond forms part of a "dynamic imine group" that may have, for example, the structure -N=CH-X- (where X is an optionally substituted arylene or heteroarylene group).

[0034] The dynamic nature of the imine group can be explained by the following non-limiting reaction scheme in which the imine group is in equilibrium with the primary amine and benzaldehyde.

Chemical formula

[0035] In the present invention, it is proposed that the dynamic imine bond forms part of a bonding system that serves to link the silica filler to the polymer chains of the diene rubber matrix. Specifically, it forms a component of the backbone of the coupling agent such that its dynamic nature provides a desirable reversible interaction that improves the recyclability of the diene rubber-silica compound. As will be appreciated, the "dynamic imine group" as defined herein also forms part of the bonding system.

[0036] It is intended that the main interaction between the silica and the diene rubber matrix in the rubber compound described herein is a reversible interaction brought about by dynamic imine bonds. However, other interactions, including other covalent and non-covalent interactions, may exist between the silica and the diene rubber. However, in order to achieve the desirable goal of recyclability of the rubber compound, the presence of any additional covalent interactions that are irreversible should be minimized. In one embodiment, there is substantially no irreversible covalent interaction between the silica and the diene rubber chains, such as may result from the presence of conventional coupling agents such as bifunctional silanes. "Substantially no" means that the degree of such irreversible covalent bonds between the silica and the diene rubber chains is less than 1 mol per mol of diene rubber, preferably less than 0.5 mol per mol of diene rubber, for example less than 0.3 mol per mol of diene rubber. It can be understood that the rubber compound substantially does not (e.g., does not) contain a coupling agent that covalently bonds silica to the diene rubber via an irreversible interaction. Other reversible non-covalent interactions that may exist between the silica and the diene rubber chains include any of electrostatic, van der Waals forces, hydrogen bonding, hydrophobic effects, and combinations thereof. However, in one embodiment, the only interaction is via a moiety incorporating the dynamic imine bond (or dynamic imine group) described herein.

[0037] As used herein, the term "silica filler" refers to particulate silica. Any known type of particulate silica that can reinforce the diene rubber matrix can be used in the present invention. As is understood, known silica materials usually contain some other components (e.g., as impurities), but the main component is silicon dioxide, i.e., SiO 2 2. The silicon dioxide content is generally at least 90 wt%, preferably at least 95 wt%, for example at least 97 wt%.

[0038] The silica materials used in the present invention are well-known in the art and include, in particular, precipitated silica (an amorphous form of silica), pyrogenic (fumed) silica, wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Silica may be used alone or in combination of two or more kinds. Silica is used in the form of discrete particles, i.e., highly dispersible granules. Silica may have a monodisperse size and a uniform shape. Alternatively, silica may be provided in the form of branched or linear clusters. Considering the ability to impart excellent rolling resistance and traction when wet to the tread compound, precipitated silica is preferred. The silica for use in the present invention has a specific surface area (e.g., nitrogen absorption surface area) in the range of 50 to 350 cm 2 / g, preferably 80 to 280 cm 2 / g, for example 120 to 230 cm 2 / g. The average particle size of silica can be in the range of about 5 nm to about 50 nm, preferably about 8 nm to about 35 nm, for example about 10 nm to about 28 nm. Commercially available grades of silica for use in the present invention are widely available from suppliers such as Evonik (Germany), and examples include Ultrasil® 7000GR and Ultrasil® VN3.

[0039] The silica used in the present invention reversibly binds to the diene rubber matrix via dynamic imine bonds. A coupling agent incorporating dynamic imine bonds forms bonds to the silica surface and the polymer chains of the diene rubber, thereby serving to link these parts. As described herein, the silica may be "pre-modified" or modified in situ by linkage to a coupling agent incorporating dynamic imine bonds. By "linkage" is meant that the silica is attached to the coupling agent by at least one attractive chemical or physical interaction. In one embodiment, the silica is chemically bonded to the coupling agent. For example, the silica can be chemically bonded via a covalent or non-covalent bond (e.g., hydrogen bond or electrostatic bond). Alternatively, the silica may be added to the coupling agent by physical interactions such as van der Waals forces, dipole-dipole interactions, dipole-induced dipole interactions, reversible click bonds or hydrophobic effects. Usually, the silica covalently bonds to the coupling agent.

[0040] The coupling agent can also be linked to the polymer chains of the diene rubber. The linkage to the diene rubber may be direct or indirect, for example via a crosslink such as a sulfide crosslink. Usually, the coupling agent can react with the diene rubber to form a chemical bond, typically a covalent bond. Advantageously, the covalent bonding of the coupling agent to the diene rubber matrix can be carried out during rubber compounding, for example during high temperature mixing of the rubber components and / or during the vulcanization process. If the bonding occurs during vulcanization, the coupling agent can react with sulfur to form sulfide crosslinks to the polymer chains of the diene rubber matrix.

[0041] In one embodiment, the silica is pre-modified to carry a coupling agent. In this embodiment, the silica is surface-modified by linkage with at least one coupling agent described herein. The silica is thus surface-modified and can carry a plurality of coupling agents. When two or more coupling agents are present, they may be the same or different. However, typically, when a plurality of coupling agents are present, they are the same chemical substance.

[0042] In some embodiments, the silica surface may be modified by the addition of one or more additional functional groups. Such functional groups may be essentially non-polar or polar, and those skilled in the art can easily select appropriate groups. The silica may be surface-treated, for example, to reduce the interaction between fillers during compounding and to improve the dispersibility in the rubber matrix. Compatibilizers (also known as "coating agents") suitable for this purpose are well-known in the art and include, but are not limited to, monofunctional silanes such as hexadecyltrimethoxysilane or propyltriethoxysilane. Other non-polar species that can be added to the surface of silica particles include aromatic groups and saturated aliphatic hydrocarbons. In some embodiments, the silica surface may be functionalized with one or more polar functional groups such as amine or carboxyl groups.

[0043] In one embodiment, the silica used in the present invention is only modified with one or more coupling agents described herein, that is, no other types of functional groups are bonded to its surface.

[0044] Each coupling agent added to the silica surface may contain at least one dynamic imine bond described herein. Each coupling agent may contain two or more dynamic imine bonds, for example, two or three such bonds. As will be understood, each dynamic imine bond forms part of a "dynamic imine group" as defined herein and provides the necessary reversible nature of the imine bond.

[0045] When multiple dynamic imine bonds are present in the coupling agent, they may each be provided in the form of the same or different dynamic imine groups. The multiple dynamic imine bonds can be formed by bonding a plurality of primary amine groups (e.g., two or three primary amine groups) to a plurality of aryl groups and / or heteroaryl groups each having an aldehyde group. In this case, each aryl group and / or heteroaryl group present in the coupling agent may be the same or different. In other cases, the multiple dynamic imine bonds may be formed between two or more primary amine groups (e.g., two or three primary amine groups) and a single aryl group or heteroaryl group having two or more (e.g., two or three) aldehyde groups capable of forming dynamic imine bonds.

[0046] In one embodiment, the silica used in the present invention contains a single dynamic imine bond that is part of a single dynamic imine group as defined in the specification.

[0047] In the present invention, it is contemplated that a wide range of coupling agents incorporating at least one dynamic imine bond can be used. The detailed nature of the coupling agent is not important as long as the coupling agent can bind (e.g., covalently) to the silica filler and (directly or indirectly) to the diene rubber matrix. As will be appreciated, the coupling agent should not contain any components that affect the performance of the rubber compound, such as groups that may have an adverse effect on the diene rubber matrix. Suitable coupling agents can be readily determined by those skilled in the art with the intended function in mind.

[0048] The coupling agent is attached to the silica surface. In one embodiment, it is attached to the silica surface via at least one covalent bond. That is, it is covalently bonded. In one embodiment, the coupling agent may be attached by two or more covalent bonds, for example, by two covalent bonds. However, usually it is attached by a single covalent bond. Due to the nature of the surface of silica having multiple silanol groups, the coupling agent usually binds to silica via a siloxane bond.

[0049] Typically, the coupling agent is an organic group having a backbone containing up to 16 atoms, preferably up to 12 atoms, and incorporates the dynamic imine bonds described herein. The coupling agent may contain, for example, up to 16 carbon atoms, for example, up to 12 carbon atoms. The coupling agent may be linear or branched and may also have one or more substituents. Typically, the coupling agent may be linear.

[0050] For example, the coupling agent has the formula (I):

Chemical formula

[0051] In one embodiment of formula (I), ring B may be an aromatic group. For example, ring B may be a phenyl ring. The coupling agent is, for example, of formula (II):

Chemical formula

[0052] In another embodiment of formula (I), ring B may be a heteroaromatic group. For example, ring B may be a 5- or 6-membered heteroaromatic group. Suitable heteroaromatic groups can contain one or more oxygen atoms, nitrogen atoms or sulfur atoms. Those containing at least one nitrogen atom are usually preferred and include pyridine rings such as 2-pyridyl.

[0053] In one embodiment of formula (I) and formula (II), each R 2 is independently, C 1-6 alkyl (preferably C 1-3 alkyl, for example, -CH 3 ), C 1-6 alkoxy (preferably C 1-3 alkoxy, for example, -OCH 3 ) and the group of formula -L 2 -R 1 selected from the group. In another embodiment, each R 2 is independently, C 1-6 alkyl (preferably C 1-3 alkyl, for example, -CH3 ) and C 1-6 alkoxy (preferably, C 1-3 alkoxy, for example, -OCH 3 ) is selected from.

[0054] In one embodiment of formula (I) and formula (II), n is 0. As can be understood, when n is 0, R 2 does not exist.

[0055] Organic linking group L 1 and L 2 The detailed nature of is not important, and suitable groups can be easily determined by those skilled in the art.

[0056] Typically, the linking group L 1 is an organic group having a skeleton containing up to 14 atoms, preferably up to 12 atoms, for example 2 to 8 atoms. It may contain, for example, up to 12 carbon atoms, for example, 2 to 8 carbon atoms. The linking group L 1 may be linear or branched and may have one or more substituents. The linking group L 1 is, for example, of formula (III):

Chemical formula

[0057] In a series of embodiments, each R in formula (III) is independently selected from -OH, C 1-3 alkoxy and C 1-3 alkyl. For example, each R is independently selected from -OH, C 1-2 alkoxy (e.g., -OCH 3 ) and C 1-2 alkyl (e.g., -CH 3 ). Typically, all R groups may be -OH.

[0058] In a series of embodiments, the group Z in formula (III) is an optionally substituted C 1-12 alkylene group, preferably a C 1-8 alkylene group, for example, a C 1-6 alkylene group or a C 1-3 alkylene group. Examples of any substituents include, for example, -OH and -NR 2 ''(each R'' is independently H or C 1-6 alkyl, preferably H). In a series of embodiments, the group Z in formula (III) is unsubstituted.

[0059] In a series of embodiments, L in formula (I) or formula (II) 2 is a single bond, that is, a direct covalent bond. When L 2 is a single bond, the functional group R 1 is directly bonded to ring B, for example, a phenyl ring.

[0060] In other embodiments, the linking group L in formula (I) or formula (II) 2 may be an organic group having a skeleton containing up to 14 atoms, preferably up to 12 atoms, for example, 2 to 8 atoms. It may contain, for example, up to 12 carbon atoms, for example, 2 to 8 carbon atoms. The linking group L 2may be linear or branched and may have one or more substituents. Typically, the linking group L 2 may be linear. L 2 is, for example, an optionally substituted C 1-12 alkylene group, preferably a C 1-6 alkylene group, for example a C 1-3 alkylene group, and may be interrupted by one or more carbon atoms. In one embodiment, L 2 may be a group of the formula -O-CH 2 -.

[0061] In formula (I) or formula (II), R 1 is a functional group capable of forming a covalent bond with the polymer chain of the diene rubber. The covalent bond may be direct (i.e., via a direct covalent bond) or indirect, i.e., via a crosslinker or crosslinking agent that covalently attaches the functional group to the polymer chain of the diene rubber. In one embodiment, R 1 is a functional group capable of forming a covalent bond with at least one unsaturated (i.e., olefinic) component of the diene rubber. In another embodiment, R 1 may be a functional group capable of forming a covalent bond with a functional group present in the diene rubber. In certain embodiments, R 1 is a functional group capable of reacting directly with the polymer chain of the diene rubber or a functional group present in the diene rubber during compounding, for example, during high-temperature mixing of the rubber components to produce a rubber compound. For example, R 1 may be a functional group capable of reacting directly with at least one -C=C- bond in the diene rubber during compounding. In other embodiments, R 1 is a functional group capable of reacting indirectly with the polymer chain of the diene rubber or a functional group present in the diene rubber, for example, in the presence of sulfur during vulcanization. R 1 may be a functional group capable of forming an indirect covalent bond with at least one -C=C- bond in the diene rubber. Suitable R 1The base can be easily determined by those skilled in the art with the intended function in mind, and includes groups widely used in coupling agents for bonding silica fillers to diene rubbers, such as reactive groups present in conventional coupling agents.

[0062] Functional groups that can react directly with the unsaturated carbon-carbon bonds in the diene rubber include groups that can react without further modification and groups that are modified in situ to generate the desired reactive groups. In one embodiment, the functional group R 1 is a mercapto group (-SH) or a protected or blocked mercapto group.

[0063] The mercapto group (-SH) can react directly with the -C=C- groups in the diene rubber without further modification and reacts at high temperatures, for example, typical temperatures used in the compounding of diene rubbers, to form sulfur crosslinks in the diene rubber chains. Protected mercapto groups are well known in the art. They are mercapto derivatives in which the mercapto group is "protected", i.e., the mercapto hydrogen is replaced by another group (the protecting group). Such groups include groups in which the protecting group is bonded to the sulfur of the mercapto group and can cleave under the conditions used in the compounding process to generate the mercapto group. Examples of protected mercapto groups include -SR, where R is C 1-6 alkyl, preferably C 1-3 alkyl, such as a short-chain, straight-chain or branched-chain alkyl group such as methyl. In one embodiment, the functional group R 1 may be -SCH 3 .

[0064] Blocked mercaptosilane coupling agents are commonly known for use in filled diene rubber compounds. Any of the blocked mercapto groups known for use with such agents can be used in the present invention. Such groups are mercapto derivatives in which the mercapto group is "blocked", i.e., the mercapto hydrogen atom is replaced by another group (the "blocking group"). Such groups include blocking groups linked to sulfur, such as carbonyl, sulfonyl, sulfinyl, phosphonyl or phosphinyl groups. In such groups, the mercaptan group is initially non-reactive due to the presence of the blocking group. That is, the blocking group substantially prevents the functional group from bonding to the diene rubber during rubber compounding. In this way, undesirable early curing of the rubber during mixing and the accompanying undesirable increase in viscosity can be avoided. If a reaction of the rubber mixture to bond the silica filler to the diene rubber is desired, a deblocking agent can be added to deblock the blocked mercapto group. If alcohol or water is present during mixing, the blocking group can be removed by hydrolysis or alcoholysis using a catalyst such as a tertiary amine or a Lewis acid. Alternatively, the deblocking agent may be a nucleophile containing a hydrogen atom exchangeable with the blocking group. Examples of such nucleophilic groups include amines containing an N-H bond, such as primary and secondary amines, imines or guanidines. Such components are widely used as components of curing systems used in the production of diene rubbers, for example, N,N'-diphenylguanidine (DPG). Any known blocked mercapto group can be used as the functional group R of the coupling agent used in the present invention. 1 as used. An example of a blocked mercapto group is the group of the formula SC(O)-C 5 H 9 present in the NXT (trademark) silane coupling agent.

[0065] Other functional groups capable of reacting directly with the unsaturated carbon-carbon bonds in the diene rubber include groups containing mono, di or polysulfide groups. Such groups include the formula -(S) x- group is included, where x is an integer from 1 to 6. For example, x may be from 1 to 4, such as 1, 2 or 4. Examples of such functional groups include -(S) x -R (where R is C1-6 alkyl, preferably C 1-3 alkyl, such as a short-chain, straight-chain or branched-chain alkyl group like methyl, etc.).) is included. The mono, di or polysulfide group may be directly bonded to the aromatic ring or heteroaromatic ring of formula (I) or formula (II), or may be bonded via the linker L 2 When directly bonded to the ring (i.e., when there is no linker), usually, the sulfide group becomes highly reactive.

[0066] The functional group capable of reacting with the functionalized diene rubber can be easily determined by those skilled in the art taking into account the nature of the functional group bonded to the polymer chain of the rubber. In one embodiment, R 1 may be an amino group capable of reacting with the carboxylated diene rubber. For example, R 1 may be a primary amine or a secondary amine. Examples of such groups include the formula -NHR x (where R x is H, C 1-6 alkyl or aryl.).

[0067] The functional group capable of indirectly covalently bonding to the diene rubber includes a group capable of bonding to the polymer chain of the diene rubber via a crosslinking group generated during the vulcanization process. For example, such a group can react with sulfur during vulcanization to form a sulfide crosslink to at least one -C=C- bond in the diene rubber. Examples of the functional group capable of forming a sulfide crosslink to the diene rubber include a group containing olefinic unsaturation, such as a group containing one or more -C=C- bonds. Such a bond can be provided as a terminal bond or a non-terminal bond of the functional group R 1 Examples of the functional group containing a terminal -C=C- bond include vinyl and allyloxy.

[0068] In formula (I) and formula (II), the group -L 2 -R1 may be present at any position of an aromatic ring or a heteroaromatic ring. For example, when ring B is a phenyl group, the group -L 2 -R 1 may be ortho, meta or para with respect to the addition point of the imine bond as a reference point. Depending on the nature and position of the group -L 2 -R 1 , it may affect the strength of the imine bond via resonance and / or inductive effects, and thus may affect its dynamic properties, i.e., the ease of disassembly and reassembly. Therefore, the nature and position of this group on the phenyl ring can be selected accordingly. The position of the group on the ring can also take into account steric considerations in view of the need to form a desired bond with the diene rubber. Considering steric considerations, for example, it may be advantageous to place the group -L 2 -R 1 at the para position on the phenyl ring. Therefore, in a series of embodiments, the coupling agent may be provided by the structure of the following formula (IV):

Chemical formula

[0069] In one embodiment, the coupling agent is of formula (V):

Chemical formula

[0070] Functional group R 1 The group -L in formula (I), (II), (IV) or (V) where R contains a terminal -C=CH bond 2 -R 1 Non-limiting examples thereof include the following:

Chemical formula

[0071] Functional group R 1 The group -L in formula (I), (II), (IV) or (V) where R contains a mercapto group or a protected mercapto group 2 -R 1 Non-limiting examples thereof include the following:

Chemical formula

[0072] Functional group R 1 The group -L in formula (I), (II), (IV) or (V) where R contains a mono, di or polysulfide group 2 -R 1 Non-limiting examples thereof include the following:

Chemical formula

[0073] Functional group R 1 The group -L in formula (I), (II), (IV) or (V) containing a blocked mercapto group 2 -R 1 Non-limiting examples of are as follows:

Chemical formula

[0074] In a preferred embodiment, -L in formula (I), (II), (IV) or (V) 2 -R 1 is selected from vinyl (-CH=CH 2 ), allyloxy (-O-CH 2 -CH=CH 2 ), thiol (-SH) and methylthiol (-SCH 3 ). In a more preferred embodiment, -L 2 -R 1 is vinyl, thiol or methylthiol.

[0075] As used herein, the term "alkyl" refers to a monovalent saturated straight-chain or branched-chain hydrocarbon chain. It may or may not be substituted. When multiple substituents are present, they may be the same or different. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, iso-pentyl, neo-pentyl, n-hexyl, etc. The alkyl group preferably contains 1-6 carbon atoms, for example, 1-4 carbon atoms.

[0076] As used herein, the term "alkoxy" refers to an -O-alkyl group, where alkyl is as defined herein. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propyloxy, etc. Unless otherwise specified, any alkoxy group may be substituted at one or more positions by suitable substituents. When multiple substituents are present, they may be the same or different.

[0077] As used herein, the term "alkylene" refers to a saturated straight-chain or branched-chain divalent carbon chain. Examples of alkylene groups include, but are not limited to, methylene (-CH 2 -), ethylene (-CH 2 CH 2 -), propylene (-CH 2 CH 2 CH 2 -), etc. Unless otherwise specified, any alkylene group may be substituted at one or more positions by suitable substituents. When multiple substituents are present, they may be the same or different.

[0078] As used herein, the term "aryl" is intended to encompass aromatic carbocyclic systems. Such ring systems can be monocyclic or polycyclic (e.g., bicyclic) and can contain at least one unsaturated aromatic ring. When they contain polycyclic rings, they may be fused or bridged. Preferably, such systems contain 6 to 20 carbon atoms, preferably 6 to 14 carbon atoms, for example 6 or 10 carbon atoms. Examples of such groups include phenyl, 1-naphthyl, and 2-naphthyl. A preferred aryl group is phenyl. Unless otherwise specified, any "aryl" group may be substituted by one or more substituents which may be the same or different.

[0079] As used herein, the term "heteroaryl" is intended to include a heterocyclic aromatic group. Such groups can be monocyclic or bicyclic and can contain at least one unsaturated heteroaromatic ring system. When these are monocyclic, they include a 5- or 6-membered ring containing at least one heteroatom selected from nitrogen, oxygen, and sulfur and contain a conjugated bond sufficient to form an aromatic system. When these are bicyclic, they may be fused to a carbocyclic or heterocyclic ring and may contain 9 to 11 ring atoms. Examples of heteroaryl groups include thiophene, thienyl, pyridyl, thiazolyl, furyl, pyrrolyl, triazolyl, imidazolyl, oxadiazolyl, oxazolyl, pyrazolyl, imidazolonyl, oxazolonyl, thiazolonyl, tetrazolyl, thiadiazolyl, benzimidazolyl, benzoxazolyl, benzofuryl, indolyl, isoindolyl, pyridonyl, pyridazinyl, pyrimidinyl, imidazopyridyl, oxazopyridyl, thiazolopyridyl, imidazopyridazinyl, oxazolopyridazinyl, thiazolopyridazinyl, and purinyl. Unless otherwise specified, any "heteroaryl" may be substituted by one or more substituents which may be the same or different.

[0080] As used herein, the term "halogen" refers to a halogen atom, for example, -F, -Cl, -Br, or -I.

[0081] When any of the groups described herein are substituted, the substituents may be the same or different and are, hereinafter, i.e., C 1-3 alkyl (for example, -CH 3 ), C 1-3 alkoxy (for example, -OCH 3 ), and -NR 6 2 (wherein each R 6 is independently selected from H or C 1-6 alkyl, preferably C 1-3 alkyl, for example, -CH 3 ).

[0082] The surface silica described in this specification can be manufactured using methods known in the art. The exact method used depends on the nature of the coupling agent selected, for example the nature of the bonding group (if present) and the functional group selected for reaction with the diene rubber, but can be readily selected by one skilled in the art. The attachment of the coupling agent to the silica may in some cases need to be appropriately functionalized, for example by incorporating one or more reactive groups that enable attachment to the silica, for example by the formation of covalent or other types of bonds as described herein.

[0083] The dynamic imine bonds described in this specification are formed by the reaction of a primary amine with a suitable aldehyde, for example an optionally substituted benzaldehyde. Typically, the primary amine has at least one functional group that enables linkage to a silica filler, for example a silane surface. Thus, the primary amine used in the production of the modified silica is typically an aminosilane. The chemical properties of such agents are well known and a skilled chemist can readily determine an appropriate method for their reaction with silica. Usually, under the selected reaction conditions, at least one hydrolyzable group present in the aminosilane is hydrolyzed to form a reactive silanol capable of forming siloxane bonds on the surface of the silica. The primary amine group of the aminosilane can then be reacted with the selected aldehyde to form the desired dynamic imine bond.

[0084] The formation of surface-modified silica can be carried out stepwise, for example, by first bonding a group containing a primary amine to the surface of silica (e.g., by covalent bonding), and then reacting the amine with a suitable aldehyde (e.g., benzaldehyde) having a functional group capable of bonding to a diene rubber. Alternatively, a group containing a primary amine can be first reacted with an aldehyde, and then the resulting group can be bonded (e.g., by covalent bonding) to silica. In another embodiment, the surface-modified silica can be formed by a single "one-step" reaction in which all reactants are involved. The solvent and conditions suitable for each reaction or stage of the reaction can be easily selected by those skilled in the art according to the nature of the reactants.

[0085] A non-limiting example of the method for producing the surface-modified silica used in the present invention is shown in the following scheme.

Chemical formula

[0086] In Scheme 2, A represents silica particles, Y is -OH or any hydrolyzable group, for example, C 1-6 is an alkoxy, B, R, Z, L 2 , R 1 , R 2 and n are as defined herein.

[0087] When ring B is a phenyl ring, a non-limiting example of the method for producing the surface-modified silica used in the present invention is shown in the following scheme.

Chemical formula

[0088] In Scheme 3, A represents silica particles, Y is -OH or any hydrolyzable group, for example, C 1-6 is an alkoxy, R, Z, L 2 , R 1 , R2 and n is as defined herein.

[0089] Following the reaction to form the surface-modified silica, the ungrafted material may be removed using conventional methods such as washing with a suitable solvent or Soxhlet extraction in water. Optionally, the residual solvent can be removed, for example, by drying at an elevated temperature. After the production of the surface-modified silica, FTIR analysis can be used to determine the success of the reaction. Where appropriate, the yield of the modified silica can be determined by methods known in the art such as thermogravimetric analysis (TGA).

[0090] The methods described above relate to the production of "pre-modified" silica for later incorporation into a diene rubber matrix to produce a desired diene rubber-silica compound. An alternative to these methods is to produce the surface-modified silica in situ. In such a method, the components necessary to form the surface-modified silica are added to the rubber during compounding. In such embodiments, the coupling agent comprising the dynamic imine bond may be pre-synthesized before being added to the rubber matrix and the silica. However, advantageously, all the reactants necessary to form the desired coupling system in situ are added to the mixture comprising the diene rubber matrix and the silica. In this case, the dynamic imine bond is typically formed in situ during the compounding of the rubber. However, the dynamic imine bond may be formed during the vulcanization process.

[0091] The surface-modified silica and its production method described herein form a further aspect of the present invention.

[0092] Accordingly, in another aspect, the present invention provides a silica filler surface-modified by the addition of a coupling agent capable of forming a linkage to a diene rubber, wherein the coupling agent incorporates a dynamic imine bond.

[0093] In another aspect, the present invention provides a method for producing a surface-modified silica filler described herein, the method including the step of chemically modifying silica by the addition of a coupling agent capable of forming a linkage to a diene rubber, the coupling agent incorporating a dynamic imine bond.

[0094] The surface-modified silica described herein acts as a reinforcing filler in a diene rubber matrix. The term "diene rubber matrix" refers to an elastomeric matrix containing a diene rubber.

[0095] Any known diene rubber can be used in the present invention, and one skilled in the art can readily select an appropriate rubber bearing in mind the intended use of the silica-diene rubber compound. Diene rubbers are well known in the art and include both natural and synthetic rubbers. Non-limiting examples of such rubbers include butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber (ENR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), isobutylene-isoprene rubber (IIR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM).

[0096] The diene rubber can be modified with one or more functional groups, and any of such functionalized diene rubbers may be used in the present invention. When the diene rubber is functionalized, any of its polymer backbone, end groups and / or side chains may be bonded to one or more functional groups. These functional groups may be incorporated into the polymer material during the production of the polymer material, or may be grafted onto the polymer thereafter. The type and position of the functional groups vary for each grade of rubber known in the art. The selection of the functionalized rubber may depend on the purpose of use of the rubber compound described herein. If any functional group can react with the coupling agent described herein, the use of the functionalized rubber can also assist in bonding the diene rubber matrix to the silica filler. Examples of the functionalized diene rubber include those carrying one or more reactive groups (e.g., alkoxysilyl groups) and / or one or more interaction groups (e.g., amino groups). Interaction groups such as amino groups can form hydrogen bonds within the rubber matrix, for example. In one embodiment, the diene rubber used in the present invention is not functionalized.

[0097] Diene rubbers, such as styrene-butadiene rubber, have functional groups added to the polymer backbone, the ends and / or the beginnings of the polymer chains, or the polymer side chains, which enable them to be chemically attached to the silica filler via the coupling agents described herein and can be used in the present invention. For example, they may, in any of the structures described herein, have the functional group R 1It may have one or more functional groups that can react directly or indirectly. In some embodiments, the diene rubber for use in the present invention is a terminally group-functionalized diene rubber, such as a terminally group-functionalized styrene-butadiene rubber. Terminally group-functionalized rubbers are well known in the art and any of those known for use in the production of rubber compounds for tire treads can be used in the present invention. In one embodiment, the diene rubber used in the present invention may be a terminally group-functionalized rubber containing a terminal carboxyl group. For example, it may include a terminally group-functionalized styrene-butadiene rubber containing a terminal carboxyl group. Such terminal carboxyl groups can be provided, for example, by terminal silane-containing carboxyl groups such as those described in International Publication No. WO 2014 / 173706, the entire content of which is incorporated herein by reference. Diene rubbers having functional groups bonded to the polymer backbone and / or the side chains of the polymer are also well known in the art for use as tire tread compounds and can be used in the same manner in the present invention.

[0098] In a series of embodiments, the diene rubber used in the present invention is suitable for use in the production of rubber compounds that can be used as tire components such as tire treads. The diene rubber used in the present invention may be, for example, a functionalized or non-functionalized styrene-butadiene rubber (SBR). Non-functionalized SBR is particularly preferred.

[0099] Styrene-butadiene rubber is well-known in the art. The term "styrene-butadiene rubber" or "SBR" as used herein is intended to generally refer to any synthetic rubber produced by the polymerization of styrene and butadiene monomers. Thus, it refers to any styrene-butadiene copolymer. SBR is commonly used in the tire industry and can be produced by well-known methods such as the copolymerization of the corresponding monomers in emulsion, suspension, or solution. The styrene monomer and the butadiene monomer can be selected in appropriate ratios depending on the use and properties of the rubber compound. For example, styrene can be present in an amount up to 80 wt%, more typically up to about 45 wt% (by weight relative to the total weight of the comonomers) in a rubber tire tread compound. The diene component is usually present in an amount of at least 50 wt%. Tire tread compounds are required to have good viscoelastic properties for contact with the road surface during use, as well as properties such as rolling resistance and traction on wet surfaces. The appropriate amount of styrene to achieve such properties is well-known in the tire industry and can be readily selected by those skilled in the art.

[0100] The selected diene rubber can be used as 100 parts of rubber in the compounds described herein, or may be blended with any elastomer or blend thereof containing both natural rubber and synthetic rubbers conventionally used for rubber compounding. Blends of different diene rubbers can also be used. Rubbers suitable for use in any blend are well known to those skilled in the art and include natural rubber, synthetic polyisoprene rubber, styrene-isoprene rubber, styrene-butadiene rubber, styrene-isoprene-butadiene rubber, butadiene-isoprene rubber, polybutadiene, butyl rubber, neoprene, acrylonitrile-butadiene rubber (NBR), silicone rubber, fluorine elastomer, ethylene acrylic rubber, ethylene propylene rubber, ethylene propylene terpolymer (EPDM), ethylene vinyl acetate copolymer, epichlorohydrin rubber, chlorinated polyethylene-propylene rubber, chlorosulfonated polyethylene rubber, hydrogenated nitrile rubber, and ethylene tetrafluoride-propylene rubber. The ratio of any polymer blend can be selected, if necessary, for example based on the viscoelastic properties of the rubber compound. Those skilled in the art can readily determine which elastomers are appropriate and their relative amounts to provide the desired range of viscoelastic properties.

[0101] In a preferred embodiment, the diene rubber selected for use in the present invention is SBR. This may be used alone or as a blend with any of the other rubbers mentioned herein. Binary blends and ternary blends are preferred. In a series of embodiments, SBR may be used in combination with butadiene rubber and / or natural rubber. When used in combination with butadiene rubber, the amount of SBR in the blend may range from 50 to 90 wt% (based on the total weight of the blend), preferably from 60 to 80 wt%, for example about 70 wt%. A binary blend of SBR:butadiene rubber present in a weight ratio of 70:30 is particularly preferred. A ternary blend comprising SBR, butadiene and natural rubber can also be used in the present invention. In such blends, SBR usually forms the main component and is present in an amount of 40 to 80 wt% (based on the total weight of the blend), preferably 50 to 70 wt%, for example about 60 wt%. The components of butadiene and natural rubber can each be present in the range of 10 to 30 wt% (based on the total weight of the blend), for example, in an amount of about 20 wt%. For example, a blend of SBR:butadiene:natural rubber present in a weight ratio of 60:20:20 may be used.

[0102] As a commercial supplier of synthetic rubbers such as SBR, Trinseo of Germany may be mentioned. A non-limiting example of the styrene-butadiene rubber used in the present invention is Sprintan 4601 (Trinseo, Germany).

[0103] Silica can be blended with the diene rubber and, optionally, other rubber materials to provide the rubber compound according to the present invention. The silica may be pre-modified to carry the coupling agent described herein, i.e., it may be "pre-modified".

[0104] The method for producing the diene rubber-silica compound described herein forms a further aspect of the present invention. Thus, in another aspect, the present invention provides a method for producing the diene rubber-silica compound described herein, which comprises reversibly binding a silica filler to a diene rubber matrix via a dynamic imine bond.

[0105] The diene rubber-silica compound in which the silica filler described herein is dispersed in a rubber matrix can be produced, for example, using methods known in the art in the production of rubber compounds, such as by compounding with other components including processing aids, curing systems, anti-degradants, pigments, additional fillers, compatibilizers for fillers, fibers, resins, etc. A person skilled in the art can easily select a combination of vulcanizable rubber compounds and perform subsequent mixing and vulcanization according to the specific rubber product desired.

[0106] For example, the vulcanizable composition can contain, in addition to the diene rubber matrix and silica filler described herein, processing aids (e.g., oils), activators (e.g., zinc oxide, stearic acid, etc.), sulfur or sulfur-donating compounds, accelerators, anti-degradants (e.g., antioxidants, anti-ozone agents, etc.), pigments, additional fillers, and compatibilizers. Zinc oxide and stearic acid function as activators for the vulcanization process by shortening the vulcanization time and also affect the length and number of crosslinks in the rubber matrix formed during curing or vulcanization. These additives can be selected according to the use of the sulfur-vulcanizable material and can be used in normal amounts.

[0107] The amount of silica mixed into the rubber compound can be selected based on the desired physical properties of the resulting compound and can depend, for example, on the presence or absence of other fillers. Suitable amounts can be easily determined by a person skilled in the art and can be, for example, in the range of about 20 to about 150 phr, preferably about 50 to about 100 phr, for example about 60 to about 90 phr (where "phr" means parts per 100 parts of rubber).

[0108] Additional reinforcing fillers may also be present, such as carbon black, carbon nanotubes, short carbon, polyamide, polyester, natural fibers, calcium carbonate, clay, alumina, aluminosilicate, etc., or any mixture thereof. However, typically, the only filler present in the composition is the silica described herein.

[0109] Processing aids improve the processability of the composition and include oils such as mineral oil, vegetable oil, synthetic oil, or any mixture thereof. These can be used in an amount of about 5 to 75 phr, preferably about 10 to 50 phr. Typical processing aids include oils such as aromatic oils. Examples of such oils include treated distillate aromatic extract (TDAE), residual aromatic extract (RAE), mild extract solvate (MES), and bio-based oilseed derivatives.

[0110] Zinc oxide can be used in an amount of about 1 to about 10 phr, preferably about 2 to about 5 phr, more preferably about 2 to about 3 phr. Stearic acid can be used in an amount of about 1 to about 5 phr, preferably about 2 to about 3 phr.

[0111] Sulfur can be used in an amount effective to achieve satisfactory curing of the composition. It can be, for example, in the range of about 1 to about 10 phr, preferably about 1 to about 5 phr, for example about 1 to about 3 phr.

[0112] Accelerators can be used in an amount of about 1 to about 5 phr, preferably about 1 to about 3 phr. Examples of accelerators include thiazole, dithiocarbamate, thiuram, guanidine, and sulfonamide. Examples of suitable accelerators include N-tert-butylbenzothiazyl sulfonamide (TBBS), N-cyclohexyl-2-benzothiazole sulfenamide (CBS), diphenylguanidine (DPG), 2-mercaptobenzothiazole (MBT), and tetrabenzylthiuram disulfide (TBZTD).

[0113] The compatibilizer can be used to reduce the formation of silica aggregates during compounding and can be present in an amount of about 0 to about 5 phr, preferably about 1 to about 3 phr. In one embodiment, no additional compatibilizer is present. Many compatibilizers are known for use in combining silica and rubber. Examples of silica-based compatibilizers include silanes such as alkylalkoxysilanes, for example hexadecyltrimethoxysilane, octyltriethoxysilane, and hexyltrimethoxysilane.

[0114] There may be other coupling agents that function to covalently bond silica to the SBR matrix, but for the reasons described herein, it is usually preferred that these are not present. If these are present, they should be provided in small amounts. The appropriate amount of any coupling agent can be determined by one of ordinary skill in the art, taking into account factors such as its molecular weight, the number of functional groups it contains, and its reactivity. Most coupling agents can be used in an equimolar amount based on the amount of silica. When using bis(triethoxysilylpropyl)tetrasulfide as the coupling agent, this can be provided in an amount of about 0.6 to about 4.8 phr per 80 phr of silica, preferably 1.2 to 3.2 phr per 80 phr of silica. Examples of coupling agents include bifunctional silanes such as bis(3-triethoxysilylpropyl)tetrasulfide (TESPT), bis(3-triethoxysilylpropyl)disulfide (TESPD), and 3-octanoylthio-1-propyltriethoxysilane. In one embodiment, no additional coupling agent is present.

[0115] The rubber compound can be manufactured by methods known in the art and includes mixing (i.e., compounding) the rubber, the silica filler, and any other components described herein to produce a rubber compound for subsequent vulcanization.

[0116] Mixing of the components is typically done at the stage where the components are added. To optimize the dispersion of the silica filler, a multi-step mixing process is usually preferred and may involve the use of multiple mixers, such as various mixers arranged in series. For example, when mixing a tire tread compound, the mixing process may include an initial mixing stage to produce a masterbatch, one or more subsequent additional non-productive mixing stages, and finally a productive mixing stage to add a curing agent (i.e., sulfur or a sulfur donor and an accelerator). Mixers that may be used are well known in the art and include, for example, an open mill or a Banbury-type mixer having tangential or intermeshing rotors.

[0117] Typically, a first masterbatch is produced by mixing rubber, a silica filler, processing aids, zinc oxide, stearic acid, anti-degradants (antioxidants, antiozonants, etc.), pigments, additional fillers, compatibilizers, coupling agents (if present). After this first masterbatch, there may follow another masterbatch to which additional fillers and additives are added, or a non-productive mixing stage where no additional components are added. Non-productive mixing stages may be used to further disperse components (such as fillers) within the rubber or to lower the viscosity of the mixed rubber compound.

[0118] To avoid premature crosslinking of the mixture and the composition, the temperature is maintained below a predetermined level. Generally, the temperature can be maintained below 150°C, preferably below 140°C. When producing the first masterbatch, the mixing can be carried out at a temperature of, for example, about 80 to about 110°C, for example, about 100°C. In non-productive mixing stages, the temperature can be raised to, for example, up to about 150°C, for example, up to about 130°C. If in situ surface modification of the silica filler (e.g., silanization) is carried out during the mixing procedure, it may be necessary to use the upper limit temperature of this range for the reaction to occur. Similarly, when adding additional compatibilizers during mixing, it may be necessary to carry out the mixing at a higher temperature so that these compatibilizers react reliably with the silica surface. The mixing time can vary, but a person skilled in the art can easily determine the mixing time based on the composition of the mixture and the type of mixer used. Usually, a mixing time of at least 1 minute, preferably 2 to 30 minutes, is sufficient to obtain the desired homogeneous composition.

[0119] The final mixing stage involves the addition of a curing agent containing an accelerator and an anti-degradant. The temperature of this mixing stage is generally lower, for example, within the range of about 40°C to about 60°C, for example, about 50°C. After this final mixing, a non-productive mixing stage without adding components may further follow.

[0120] To obtain a vulcanizable rubber compound, the most suitable type of mixing can be easily selected. The mixing speed can be easily determined, for example, in the range of about 20 to about 100 rpm, for example, in the range of about 30 to about 80 rpm, preferably at a speed of about 50 rpm.

[0121] When introducing a coupling agent that in-situ surface-modifies silica to incorporate dynamic imine bonds, the modification of the silica surface is typically carried out during one or more of the non-productive mixing steps. The components necessary to form the coupling agent (e.g., aminosilane and substituted benzaldehyde) can be introduced simultaneously within one of the non-productive mixing steps. They then react with each other and also with the silica surface to form the desired surface-modified silica filler. Alternatively, the components that react to form the coupling agent may be added separately during the same or different steps as the non-productive mixing. For example, aminosilane may be added together with diene rubber, unmodified silica, and process oil in the first step of non-productive mixing, followed by the addition of substituted benzaldehyde together with zinc oxide and stearic acid in the second step of non-productive mixing. This sequential addition of reactants can be advantageous in ensuring that the aminosilane first reacts reliably with the surface of the silica, avoiding and at least minimizing the adsorption of benzaldehyde onto the silica surface.

[0122] The production of the diene rubber-silica compound described herein, in which the silica is surface-modified in-situ, represents a preferred embodiment of the present invention, not only from the perspective of the convenience of the production method but also from the perspective of the potential impact on the dynamic properties of the resulting rubber compound. In some cases, at least one of the dynamic properties of the final rubber compound may be improved compared to the same rubber compound produced using pre-modified silica.

[0123] The vulcanizable rubber compound can be supplied as an uncured (so-called "green") tire component for final vulcanization to cure the composition. Curing to crosslink the rubber component and, if necessary, curing to bind a coupling agent to the diene rubber can be carried out by known methods. For example, in the tire industry, an uncured rubber (so-called "green body") is manufactured and subsequently cured in a press mold, while at the same time the rubber component is crosslinked and the components are formed into the final tire. Vulcanization mainly cures the rubber by crosslinking with sulfur crosslinks. The vulcanization method is known. Suitable vulcanization conditions usually include heating at a temperature in the range of 120 to 200 °C for 5 to 180 minutes.

[0124] The vulcanizable rubber composition forms a further aspect of the present invention. Thus, in another aspect, the present invention provides a vulcanizable rubber composition comprising a diene rubber matrix in which a silica filler is dispersed, wherein the silica filler is reversibly bound to the diene rubber matrix via a dynamic imine bond.

[0125] The vulcanized rubber compound obtained directly or obtainable by crosslinking any of the vulcanizable rubber compositions described herein is also part of the present invention.

[0126] A method for producing a vulcanized rubber compound also forms part of the present invention. Such methods include methods for pre-modifying silica to bind a coupling agent incorporating a dynamic imine bond, and methods for surface-modifying the silica described herein in situ. The vulcanized rubber compound produced by any of the methods described herein is also part of the present invention.

[0127] Thus, in another aspect, the present invention provides a method for producing a vulcanized diene rubber-silica compound comprising a diene rubber matrix in which a silica filler reversibly bound to the diene rubber matrix via a dynamic imine bond is dispersed, said method comprising the following steps:. (i) A step of surface-modifying a silica filler by adding a coupling agent that incorporates a dynamic imine bond and can form a bond with a diene rubber matrix during compounding and / or vulcanization. (ii) A step of providing a vulcanizable rubber composition by compounding the obtained surface-modified silica filler with a diene rubber matrix, and (iii) A step of subjecting the vulcanizable rubber composition to vulcanization.

[0128] In yet another aspect, the present invention provides a method for producing a vulcanized diene rubber-silica compound comprising a diene rubber matrix in which a silica filler reversibly bonded to the diene rubber matrix via a dynamic imine bond is dispersed, said method comprising the following steps: (i) Adding a silica filler to a diene rubber matrix together with one or more compounds capable of reacting with the silica filler to provide a surface-modified silica filler incorporating a dynamic imine bond and having a coupling agent added thereto that can form a bond with the diene matrix during compounding and / or vulcanization. (ii) A step of providing a vulcanizable rubber composition comprising the surface-modified silica filler by compounding the obtained composition, and (iii) A step of subjecting the vulcanizable rubber composition to vulcanization.

[0129] When the silica is surface-modified in situ, a person skilled in the art can easily select a compound that can react with the silica filler to provide the desired surface-modified silica filler, taking into account the nature of the desired coupling agent incorporating a dynamic imine bond. In one embodiment, the surface-modified silica can be produced in situ by the reaction of a silica filler with compounds of general formulas (VI) and (VII): [Chemical formula] [wherein, Y is -OH or any hydrolyzable group, for example, C 1-6 alkoxy, Each R is independently selected from -OH, C 1-6 alkoxy (preferably C 1-3 alkoxy) and C 1-6 alkyl (preferably C 1-3 alkyl), Z is an optionally substituted C 1-12 alkylene group, and the C 1-12 alkylene group is interrupted by one or more groups selected from -O-, -SiR' 2 - (each R' is independently -OH, C 1-6 alkoxy or C 1-6 alkyl. ), -PR''-, -NR''- and -OP(O)(OR'')O- (R'' is H or C 1-6 alkyl, preferably C 1-3 alkyl, for example methyl. ) and may be interrupted, Ring B is an aromatic group or a heteroaromatic group, L 2 is either a single bond or an organic linking group, R 1 is a functional group capable of forming a bond with the diene rubber matrix, Each R 2 is independently C 1-6 alkyl (preferably C 1-3 alkyl, for example, -CH 3 ), C 1-6 alkoxy (preferably C 1-3 alkoxy, for example, -OCH 3 ), halogen (for example, F, Cl, Br or I), and a group of the formula -L 2 -R 1 selected from the group n is an integer from 0 to 4, preferably from 0 to 2, for example 0 or 1.

[0130] The compounds of formulas (VI) and (VII) can be contacted simultaneously with a silica filler to form surface-modified silica in situ. However, advantageously, they can be contacted sequentially with the silica filler, for example, in separate non-productive mixing steps of the rubber compounding process. The compound of formula (VI) can, for example, first be contacted with the silica filler and subsequently with the compound of formula (VII). In this way, the adsorption of the compound of formula (VII) onto the silica surface is minimized.

[0131] In another embodiment, the present invention provides a vulcanized diene rubber-silica compound obtained by, directly obtained by, or obtainable by any of the methods described herein. Such compounds obtained by a process in which a surface-modified silica filler is generated in situ form a preferred embodiment of the present invention.

[0132] The rubber compounds described herein are particularly used in the manufacture of vehicle tires, in particular in the manufacture of tire parts such as tire treads. Tire treads can be used in any vehicle tire, but are particularly used in the manufacture of automobile tire treads. Other uses of the rubber compound include vibration dampers, sidewall rubber, inner liner rubber, bead filler rubber, body ply rubber, skim shock rubber, and tread rubber.

[0133] Accordingly, in another aspect, the present invention provides the use of the diene rubber-silica compounds described herein as parts of vehicle tires or in the manufacture of parts of vehicle tires.

[0134] In another aspect, the present invention provides vehicle tire parts such as tire treads made from the diene rubber-silica compounds described herein. A vehicle tire comprising the vehicle tire part also forms part of the present invention.

[0135] The assembly and manufacturing methods of tire components are well known in the art. Following the assembly of a "green" tire, compression molding is performed in a suitable mold, and the final tire is manufactured by vulcanization.

[0136] The rubber compound according to the present invention may also be used for applications other than tires, such as the manufacture of hoses and seals.

[0137] In the present invention, by replacing a conventional filler with a chemically modified silica filler, a rubber compound having not only acceptable wet traction and rolling resistance for use as a tire tread rubber compound but also excellent physical properties can be obtained. In the tire industry, various tests of rubber compounds are used to predict the properties of cured tires. These properties include the following, namely, Payne effect: This indicates the extent of the filler network and is measured using a rubber process analyzer. Mechanical properties such as tensile strength, elongation at break point, reinforcement index, etc.: ASTM D412 standard using a universal testing machine Zwick Z05 (Zwick, Germany) at a crosshead speed of 500 mm / min. The rebound rate at 60 °C is a predictor of the rolling resistance of the tread compound. An increase in the rebound rate at 60 °C, when compared to the compound of interest, indicates a low rolling resistance. The rebound force can be measured using Zwick 5109 (Zwick, Germany) in accordance with ISO 8307. Hardness, Shore A can be measured using a universal hardness tester (Zwick, Germany) in accordance with DIN 53505. Dynamic mechanical properties: These can be measured using a Gabo-Netzsch Eplexor at a frequency of 10 Hz with a dynamic strain of 1% below 0 °C and 3% at room temperature. The loss factor (tangent δ, i.e., tan δ) at 0 °C is an indicator of wet traction. When compared to a control compound, an increase in tan δ at 0 °C correlates with an improvement in the wet traction of the tread compound. The tan δ at 60 °C is an indicator of rolling resistance. When compared to a control compound, a lower resulting value indicates a decrease in rolling resistance.

[0138] The diene rubber-silica compounds described herein can be recycled using methods known in the art. Recycling includes devulcanization of the rubber. During recycling, the rubber compound is usually cut into a finely ground form. The presence of dynamic imine bonds between the silica filler and the diene rubber chains allows for further treatment of the rubber compound, thereby enabling the cleavage of reversible bonds without requiring harsh treatment conditions. For example, methods such as mild chemical, thermophysical, or biological treatment can be used. After removing impurities, the rubber can be combined with one or more additional polymer components and converted into a new polymer material.

[0139] Accordingly, in a further aspect, the present invention provides a method for recycling a diene rubber-silica compound described herein, the method comprising the step of devulcanizing the compound and optionally the step of recovering the diene rubber.

[0140] The method of recycling may include a step of shearing a compound to form a finely crushed rubber composition and then subjecting it to desulfurization. The shearing of the diene rubber-silica compound can be achieved using any known method such as pulverization. After being finely crushed, desulfurization can be carried out to regenerate the rubber. Examples of desulfurization methods include physical processes (e.g., mechanical, thermomechanical, microwave, and ultrasonic), or chemical processes (e.g., the use of radical scavengers, nucleophilic additives, catalyst systems or chemical probes). Thermal desulfurization can be carried out at a temperature of 180 to 300 °C. Thermochemical desulfurization can be achieved by using a desulfurization aid (e.g., disulfides such as diphenyl sulfide, dibutyl sulfide, di(2-aminophenyl) disulfide) and using a temperature of 180 to 300 °C.

[0141] The recovered diene rubber can be blended with the original unused diene rubber and / or other additional polymer components and used in the production of new polymer materials.

Brief Description of the Drawings

[0142] The present invention is further illustrated by the following non-limiting examples and the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Example

[0143] [Test Procedure] 1. Payne effect The Payne effect was measured using a Rubber Process Analyzer RPA Elite (TA instruments) at a frequency of 1.6 Hz and a temperature of 60 °C with a strain sweep from 0.1% to 100% for both cured and uncured samples. The cured samples were previously vulcanized in the apparatus chamber according to the vulcanization conditions of 160 °C.

[0144] 2. Elastic modulus, tensile strength, and elongation at break The elastic modulus, tensile strength (stress at maximum strain), and elongation at break were measured using a universal testing machine Zwick Z05 (Zwick, Germany) operating at a crosshead speed of 500 mm / min in accordance with ASTM D412. The elastic modulus (100% (M100)) and 300% (M300)), tensile strength (Ts), and elongation at break (Eb) were calculated according to the calculations of ASTM D412. The reinforcement index was determined as the ratio of M300 to M100.

[0145] 3. Resilience The resilience of the rubber sample, which is based on the ratio of the returned energy to the supplied energy, was measured using a testing machine Zwick 5109 (Zwick, Germany) in accordance with ISO 8307. The resilience rate was calculated according to ISO 8307.

[0146] 4. Hardness, Shore A The Shore A hardness was measured using a universal hardness tester (Zwick, Germany) in accordance with DIN 53505.

[0147] 5. Loss elastic modulus and storage elastic modulus, and loss factor (tanδ) The dynamic mechanical measurements of the vulcanized samples were performed using a Gabo-Netzsch Eplexor. The measurements were carried out at a frequency of 10 Hz, a dynamic strain of 1% below 0 °C, and 3% at room temperature (RT). The change in strain at room temperature was investigated due to the softening of the rubber at high temperatures where noise could occur during measurement.

[0148] 6. Mechanical Properties at High Temperatures The mechanical properties of the compound at 100 °C were measured by a universal testing machine Zwick Z010 (Zwick, Germany) operated at a crosshead speed of 500 mm / min and a limit strain of 330%. The tests were carried out in a thermostatic chamber at 100 °C. The measurement of the dynamic properties of the vulcanized compound before and after cycling the sample with a tensile machine was performed with a Gabo-Netzsch Eplexor. The measurements were carried out at a frequency of 10 Hz, a dynamic strain of 1% below 0 °C, and 3% at room temperature (RT). The change in strain at room temperature was investigated due to the softening of the rubber at high temperatures where noise could occur during measurement. The cycling of the sample was performed with a universal testing machine Zwick Z010 (Zwick, Germany) operated at a crosshead speed of 500 mm / min and a limit strain of 200%. All samples were cycled 5 times at 100 °C.

[0149] 7. Creep Deformation The creep test was carried out using a universal testing machine Zwick Z010 (Zwick, Germany). A force of 15 N was applied to the sample and maintained for 1 hour. After that, the stress was released and the change in strain of the sample was measured for an additional 1 hour. The experimental temperature was 100 °C. The procedure of the creep test is shown in Figure 1.

[0150] [Manufacture of the Rubber Compound According to the Present Invention] The rubber compound for tire treads was manufactured using non-functionalized solution styrene butadiene rubber (SSBR) as the polymer matrix and silica as the filler. The modification of silica was carried out by reacting silica with an aminosilane and a benzaldehyde compound to obtain dynamic imine bonds. This reaction was carried out either during the mixing of the rubber compound (i.e., in situ) or before mixing with the rubber compound (i.e., the silica was "pre-modified").

[0151] [Materials] Rubber: Non-functionalized SSBR: Spirintan 4601 (Trinseo, Germany) Silica: ULTRASIL® 7000 GR (Evonik Resource Efficiency GmbH, Germany) 3-Aminopropyltriethoxysilane (Sigma Aldrich, Netherlands) 3-Vinylbenzaldehyde (Sigma Aldrich, Netherlands) 4-Allyloxybenzaldehyde (Sigma Aldrich, Netherlands) 4-(Methylthio)benzaldehyde (Sigma Aldrich, Netherlands) TDAE (Hansen & Rosenthal, Germany), Zinc oxide (Millipore Sigma, Germany), Stearic acid (Millipore Sigma, Germany), Sulfur (Caldic B.V., Netherlands), N-Tert-butylbenzothiazylsulfonamide (TBBS) (Caldic B.V., Netherlands), Bis(3-triethoxysilylpropyl)disulfide (TESPD): Si266® (Evonik Resource Efficiency GmbH, Germany) Hexadecyltrimethoxysilane (Sigma Aldrich, Netherlands).

[0152] Silica modification: The modification of silica in situ was carried out by reacting an aminosilane (3-aminopropyltriethoxysilane) with each of the following benzaldehydes during the mixing of the rubber compound: 3-vinylbenzaldehyde, 4-allyloxybenzaldehyde, 4-(methylthio)benzaldehyde

[0153] The pre-modification of silica was carried out by reacting silica with an aminosilane (3-aminopropyltriethoxysilane) and a selected benzaldehyde in the following two-step reaction:

[0154] Step 1: Reaction of silica with aminosilane The amount of silica used was 100 g, and that of the aminosilane was 8 g. The reaction was carried out at 70 °C for 24 hours using toluene as a solvent. After the first step of the reaction, the product was filtered.

[0155] Step 2: Reaction with benzaldehyde The reaction of the pre-modified silica with the selected benzaldehyde was carried out at 40 °C for 24 hours using toluene as a solvent. The obtained product was extracted in toluene using a Soxhlet unit for 24 hours. The amounts of different benzaldehydes used were as follows: 3-vinylbenzaldehyde 4.8 g, 4-allyloxybenzaldehyde 5.9 g, 4-(methylthio)benzaldehyde 5 g

[0156] [Manufacture of the rubber compound according to the present invention] The rubber compound (SSBR / modified silica) according to the present invention was manufactured in a closed mixer (Brabender Plasticorder 350S, Duisburg, Germany) at a filling rate of 0.7, an initial temperature of 100 °C, and a rotor speed of 50 rpm. Samples were manufactured according to the formulation in Table 1 and the mixing procedure in Table 2.

[0157]

Table 1

[0158]

Table 2

[0159] The details of the final rubber compound according to the present invention are shown in Table 3 below.

[0160]

Table 3

[0161] [Manufacture of reference rubber] Two reference rubber compounds were manufactured. The details are shown in Table 4.

[0162]

Table 4

[0163] In Reference 1, the bifunctional silane coupling agent TESPD was used to bond silica and SSBR. In Reference 2, the monofunctional silane (hexadecyltrimethoxysilane) was used for in-situ modification of silica. The reference compounds were manufactured according to the formulation shown in Table 5 and according to the mixing procedure (the silane is "TESPD" or hexadecyltrimethoxysilane as required) used for the compound according to the present invention shown in Table 2.

[0164]

Table 5

[0165] [Testing of rubber compounds] All rubber compounds were subjected to various tests outlined in the test procedure. The results of the measured Payne effect are shown in Table 6 and in Figures 2 and 3 of the accompanying drawings.

[0166]

Table 6

[0167] The results of the unvulcanized and vulcanized Payne effects indicate that the rubber compound according to the present invention exhibits a higher Payne effect than the reference compound and shows a strong filler network. The higher value of G’ at 100% strain obtained for the vulcanized Payne effect of the rubber compound of the present invention compared to the reference compound indicates a higher interaction between the filler and the rubber in these compounds. The Payne effect of the compounds of the present invention is similar regardless of whether the silica was “pre-modified” (E1 - E3) or modified in situ (E4 - E6).

[0168] The results of the mechanical properties of the vulcanized compounds are shown in Table 7 and the attached Figures 4 and 5.

[0169] [Table 7]

[0170] The results of the mechanical properties indicate that all the compounds of the present invention have a reinforcement index equivalent to that of reference compound 1. All the compounds according to the present invention also show a higher elongation at break and higher tensile strength than reference compounds 1 and 2.

[0171] The resilience characteristics and hardness of the compounds are shown in Table 8. The results of resilience indicate that all the compounds of the present invention show values equivalent to those of reference compound 1. Therefore, their dynamic properties are equivalent to those of rubber compounds using TESPD, a state-of-the-art bifunctional silane coupling agent. Reference compound 2 contains a coating agent that does not react with the rubber and does not bind the silica to the rubber matrix, resulting in a low resilience level. The higher resilience results of the compounds of the present invention are evidence of a high binding efficiency. Regarding hardness, all the compounds according to the present invention showed higher values than reference compounds 1 and 2.

[0172] [Table 8]

[0173] The results of the dynamic mechanical measurements of the vulcanized samples are shown in Table 9 and the attached FIG. 6.

[0174]

Table 9

[0175] Analyzing the loss factor (tanδ) as a function of temperature for the compounds of the present invention, E4 and E6 have lower tanδ values at 60 ° C compared to reference compounds 1 and 2 (indicating better rolling resistance), and E5 has a similar tanδ value at 60 ° C as reference compound 1. All compounds according to the present invention have lower tanδ values at 0 ° C and lower maximum tanδ values than reference compounds 1 and 2.

[0176] The recombinability of the new bonds generated by the silica modification according to the present invention was analyzed by studying the mechanical response of the compounds at high temperatures and analyzing the changes in the dynamic properties after subjecting the compounds to cycling (fatigue tests).

[0177] The results of the mechanical properties measured at 100 ° C are shown in FIG. 7, which show that the compounds according to the present invention exhibit similar resistance to high temperatures. All compounds except reference compound 2 broke before reaching the critical strain (330% strain) set for the experiment. However, all compounds according to the present invention reached a higher tensile strength than reference compound 1, and E5 also showed a higher elongation at break.

[0178] The results of the dynamic mechanical measurements of the vulcanized compounds before and after cycling on a tensile machine are shown in Table 10.

[0179]

Table 10

[0180] Compounds E4 and E6 according to the present invention exhibit superior performance compared to reference compound 1 in terms of dynamic properties after being subjected to 5 cycles at 100°C up to 200% strain. Both Compounds E4 and E6, after the cycles, have a lower tanδ value at 60°C (indicating better rolling resistance) than reference compound 1, a higher tanδ value at 0°C, and a higher maximum tanδ value (indicating superior wet grip).

[0181] The recombinability of the new bonds generated by silica modification according to the present invention was further analyzed by conducting a creep experiment. The results are shown in FIG. 8. The results indicate that E5 and E6 reach a higher elongation in response to the applied force and the recovery of the original shape is almost the same as that of reference compound 1. For E6, not only is the elongation significantly lower, but the residual strain is also lower compared to other compounds.

[0182] The present invention has been described with reference to exemplary embodiments. Changes and modifications are considered to form part of the present invention as long as they are within the scope of the present disclosure and the appended claims. The scope of the present disclosure should be determined with reference to the claims and is considered to include equivalents.

Claims

1. A diene rubber-silica compound comprising a diene rubber matrix in which a silica filler is dispersed, wherein the silica filler is reversibly bonded to the diene rubber matrix via a dynamic imine bond.

2. The diene rubber-silica compound according to claim 1, wherein the diene rubber matrix comprises styrene-butadiene rubber.

3. The silica filler incorporates a dynamic imine bond and is surface-modified with a coupling agent that binds to the diene rubber matrix, and the coupling agent has the formula (I): 【Chemical 1】 [Wherein, * indicates the attachment point of the coupling agent to the silica surface, Ring B is an aromatic group or a heteroaromatic group, L １ is an organic linking group, L ２ is either a single bond or an organic linking group, R １ is a functional group capable of forming a bond with the diene rubber matrix, Each R ２ is, independently of one another, C １－６ alkyl, C １－６ alkoxy, halogen, and Formula - L ２ -R １ group selected from, n is an integer from 0 to 4. ] The diene rubber-silica compound according to claim 1 or 2, having the structure of.

4. The coupling agent has the formula (II): 【Chemical 2】 [wherein, *, L １ , L ２ , R １ , R ２ and n are as defined in claim 3.], The diene rubber-silica compound according to claim 3, having the structure of

5. The coupling agent has the formula (IV): [Chemical Formula 3] (IV) [wherein, *, L １ , L ２ , R １ , R ２ and n are as defined in claim 3.], The diene rubber-silica compound according to claim 3, having the structure of

6. L １ is the formula (III): 【Chemical Formula 4】 [Wherein, Each R is independently selected from -OH, C １－６ alkoxy and C １－６ alkyl, Z is an optionally substituted C １－１２ alkylene group, and the C １－１２ alkylene group may be interrupted by one or more groups selected from -O-, -SiR' 2 -(each R' is independently -OH, C １－６ alkoxy or C １－６ alkyl).), -PR''-, -NR''- and -OP(O)(OR'')O- (R'' is H or C １－６ alkyl).). The diene rubber-silica compound according to claim 3, which is a group of ].

7. The coupling agent has the formula (V): [Chemical Formula 5] [wherein, *, L ２ and R １ are as defined in claim 3, and each R is as defined in claim 6.] The diene rubber-silica compound according to claim 3, having the structure of

8. L ２ The diene rubber-silica compound according to claim 3, wherein L is a single bond.

9. R １ The diene rubber-silica compound according to claim 3, wherein R is selected from the group consisting of a mercapto group; a protected mercapto group; a blocked mercapto group; a mono-, di- or polysulfide group; and a group containing a carbon-carbon double bond.

10. -L ２ -R １ The group of has the following structure: 【Chemical Formula 6】 [Here, p is an integer from 1 to 6, m is an integer from 1 to 6. ] The diene rubber-silica compound according to claim 3, represented by one of.

11. -L ２ -R １ The group of has the following structure: 【Chemical Formula 7】 [Here, x is an integer from 1 to 6, p is an integer from 1 to 6, m is an integer from 1 to 6. ] The diene rubber-silica compound according to claim 3, represented by one of.

12. -L ２ -R １ The group of has the following structure: 【Chemical 8】 [Here, p is an integer from 1 to 6, m is an integer from 1 to 8. ] The diene rubber-silica compound according to claim 3, represented by one of.

13. -L ２ -R １ is vinyl (-CH=CH ２ ) allyloxy (-O-CH ２ -CH=CH ２ ), thiol (-SH) and methylthio (-SCH ３ ), the diene rubber-silica compound according to claim 3, selected from.

14. The diene rubber-silica compound according to claim 1 or 2, which is vulcanizable.

15. A vulcanized rubber compound directly obtained, or obtainable, by crosslinking the diene rubber-silica compound according to claim 14.

16. A method for producing the diene rubber-silica compound according to claim 1, comprising the following steps: (i) A step of surface-modifying the silica filler by adding a coupling agent that incorporates a dynamic imine bond and can form a linkage with the diene rubber matrix during compounding and / or vulcanization. (ii) providing a rubber composition capable of being vulcanized by compounding the obtained surface-modified silica filler with a diene rubber matrix, and (iii) subjecting the rubber composition capable of being vulcanized to vulcanization A method comprising:

17. A method for producing a diene rubber-silica compound according to claim 1, comprising the following steps: (i) adding a silica filler to a diene rubber matrix together with one or more compounds capable of reacting with the silica filler, incorporating a dynamic imine bond, and adding a coupling agent capable of forming a linkage with the diene matrix during compounding and / or vulcanization to provide a surface-modified silica filler; (ii) providing a rubber composition capable of being vulcanized and containing the surface-modified silica filler by compounding the obtained composition, and (iii) subjecting the rubber composition capable of being vulcanized to vulcanization A method comprising:

18. A diene rubber-silica compound obtained directly or obtainable by the method according to claim 16 or claim 17.

19. A vehicle tire part made from the compound according to claim 1 or 2.

20. A vehicle tire comprising the vehicle tire part according to claim 19.

21. A silica filler surface-modified by the addition of a coupling agent capable of forming a reversible linkage with a diene rubber, the coupling agent incorporating a dynamic imine bond.

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