Branched diene rubber

Abstract

The invention relates to a branched and optionally functionalized polydiene rubber, a method of making the polydiene rubber and a composition comprising the cured polydiene rubber.

Description

Branched Diene RubberBackground

[0001] The invention relates to a branched and optionally functionalized poly diene rubber, a method of making the polydiene rubber, and a composition comprising the cured polydiene rubber.

[0002] Diene rubbers are widely used as a raw material for producing tires. Coupling agents may be used for improving diene rubber processing. Coupling agents link the polymer chains of the rubbers with each other to create a branched or star-shaped polymer architecture. This leads to a broader molecular weight distribution of the polymers and reduces the Mooney viscosity of compounds containing them and facilitates their processing. Examples of known coupling reagents include silicon tetrachloride, methyltrichlorosilane, dimethyldichlorosilane, tin tetrachloride, dibutyltin dichloride, tetraalkoxysilanes, derivatives of ethylene glycol diglycidyl ether, l,2,4-tris(chloromethyl)benzene. In US 2005 / 0107541 Al the use of a substituted silasesquioxane, a polycyclic substituted poly siloxane, as a coupling agent is reported.

[0003] Diene rubber, such as butadiene, isoprene and styrene butadiene rubber, is a key material for the production of tires. The compatibility of the rubber with the fdler, such as silica or carbon black, can be improved by introducing polar functionalities to the polymer chain. An improved polymer-filler interaction allows for a better fdler dispersion and improved tire properties, such as a lower rolling resistance and higher wet grip. Thus, functionalized diene rubber is of great interest to the tire industry. However, compounds containing functionalized rubber are typically more challenging to process, i. e. compounds have high Mooney viscosities and show poor extrusion performance.

[0004] WO 2023 / 104783 Al relates to a method of making a poly diene rubber comprising (i) polymerizing at least one aliphatic conjugated diene monomer to produce a polymer having reactive polymer chain ends, (ii) reacting at least some of the reactive polymer chain ends with a coupling agent comprising from 2 to 20 unsaturated siloxane units, (iii) using at least one functionalization agent for introducing at least one functional group to the polymer, wherein (iii) is carried out before, after or during step (ii).

[0005] WO 2023 / 104784 Al relates to a method of making a poly diene rubber comprising (i) polymerizing at least one aliphatic conjugated diene monomer to produce polymers having reactive polymer chain ends, (ii) reacting at least some of the reactive polymer chain ends with a coupling agent comprising from 2 to 20 unsaturated siloxane units.

[0006] The polydiene rubbers of the prior art are not satisfactory in every respect.

[0007] It is therefore an object of the invention to provide polydiene rubbers that have advantages compared to the prior art, especially provide an improved balance between processability and dynamic properties.

[0008] This object has been achieved by the subject-matter of the patent claims.Summary

[0009] A first aspect of the invention relates to a branched and optionally functionalized polydiene rubber comprising- repeating units derived from at least one aliphatic conjugated diene monomer; and- branching units; preferably derived from at least one siloxane; wherein the poly diene rubber has(i) a glass transition temperature (Tg) of at most -37°C, determined according to DIN EN ISO 11357;(ii) a Mooney viscosity ML 1+4 at 100°C within the range of from 50 MU to 160 MU; determined according to EN ISO 289; and(iii) a A5 value within the range of from 13° to 32°, determined by measuring the phase angle 5 by means of a rubber process analyzer (RPA) at 100°C in a frequency sweep from 0.01 Hz to 40 Hz and a deflection angle of 0.5° (shear amplitude of 6.98%), wherein A5 is the 5 value at 0.1 rad / sec minus the 5 value at 100 rad / s.

[0010] A second aspect of the invention relates to a method of making the poly diene rubber, said method comprising the steps of:(a) polymerizing the at least one aliphatic conjugated diene monomer to produce a polymer having reactive polymer chain ends;(b) reacting at least some of the reactive polymer chain ends with the at least one siloxane; and(c) optionally, introducing at least one functional group to the polydiene rubber by means of a functionalization agent, wherein optional step (c) is carried out before, after or during step (b).

[0011] A third aspect of the invention relates to a curable composition comprising the polydiene rubber according to the invention, and at least one vulcanization agent for curing the polydiene rubber; preferably wherein the content of the vulcanization agent is within the range of from 0.5 to 10 parts by weight per 100 parts by weight of diene rubber.

[0012] A fourth aspect of the invention relates to a composition comprising a cured polydiene rubber obtained by curing the curable composition according to the invention.

[0013] It has been surprisingly found that compared to state-of-the-art reference polymers, branched diene polymers having a delta delta value (RPA Frequency Sweep 100 °C; 0.5°= 6.98 %; phase angle delta between 0.1 and 100 rad / s) between 13° and 32° have improved filler dispersion, processabilityand dynamic properties when used in tire compounds. The branched diene polymers have preferably a glass transition temperature (Tg) below -34 °C.

[0014] Further, it has been surprisingly found that the branched diene polymers exhibit excellent fdler dispersion, processability and dynamic properties when used in tire compounds.

[0015] The inventive branched diene polymers contain repeating units derived from a diene monomer, a Si-containing functional group and a delta delta value (A5 value, RPA Frequency Sweep 100 °C; 0.5°= 6.98 %; phase angle delta between 0.1 and 100 rad / s) between 13° and 32°. A possible approach to synthesize such polymers is via anionic polymerization and a subsequent coupling step with 2,4,6-tri- methyl-2,4,6-trivinylcyclotrisiloxane.Detailed Description

[0016] The invention will be further illustrated in the following detailed description.

[0017] In the following description certain standards (ASTM, DIN, ISO etc.) may be referred to. If not indicated otherwise, the standards are used in the version that was in force on May 1, 2024. If no version was in force at that date because, for example, the standard has expired, then the version is referred to that was in force at a date that is closest to May 1, 2024.

[0018] In the following description the amounts of ingredients of a composition or a polymer may be indicated interchangeably by “weight percent”, “wt. %” or “% by weight”. The terms “weight percent”, “wt. %” or “% by weight” are based on the total weight of the composition or polymer, respectively, which is 100 %, unless indicated otherwise.

[0019] The term “phr” means “parts per hundred parts of rubber”, i.e., the weight percentage of an ingredient of a composition containing one or more rubber is based on the total amount of rubber which is set to 100% by weight. Therefore, total weight of the composition is usually greater than the amount of rubber and can be greater than 100% by weight.

[0020] Ranges identified in this disclosure are meant to include and disclose all values between the endpoints of the range and its end points, unless stated otherwise.

[0021] The term “comprising” is used in an open, non-limiting meaning. The phrase “a composition comprising ingredients A and B” is meant to include ingredients A and B but the composition may also have other ingredients. Contrary to the use of “comprising” the word “consisting of’ is used in a narrow, limiting meaning. The phrase “a composition consisting of ingredients A and B” is meant to describe a composition of ingredients A and B and no other ingredients.

[0022] The polydiene rubber according to the invention is branched. The branching is preferably achieved by means of siloxane-based coupling agents that are described in detail below. In consequence of using such siloxane-based coupling agents, the poly diene rubber according to the invention comprises branching units, preferably derived from at least one siloxane.

[0023] The polydiene rubber according to the invention may optionally be further modified, preferably functionalized by Si-containing functional groups. Such functionalization is preferably achieved by means of functionalizing agents that are described in detail below.

[0024] The poly diene rubber according to the invention has a glass transition temperature (Tg) of at most -37°C, determined according to DIN EN ISO 11357.

[0025] Preferably, the glass transition temperature is at most -40°C, preferably at most -43°C, more preferably at most -47°C, still more preferably at most -50°C, yet more preferably at most -53°C, even more preferably at most -56°C, most preferably at most -60°C, and in particular at most -63°C.

[0026] Preferably, the glass transition temperature is at least -90°C, preferably at least -87°C, more preferably at least -83°C, still more preferably at least -80°C, yet more preferably at least -77°C, even more preferably at least -73°C, most preferably at least -70°C, and in particular at least -67°C.

[0027] Preferably, the glass transition temperature is within the range of from -90°C to -40°C, preferably -85°C to -45°C, more preferably -80°C to -50°C, still more preferably -75°C to -55°C, and yet more preferably -70°C to -60°C.

[0028] The poly diene rubber according to the invention has a Mooney viscosity ML 1+4 at 100°C within the range of from 50 MU to 160 MU; determined according to EN ISO 289.

[0029] Preferably, the Mooney viscosity ML 1+4 at 100°C is at least 55 MU, preferably at least 60 MU, more preferably at least 65 MU, still more preferably at least 70 MU, yet more preferably at least 75 MU, even more preferably at least 80 MU, most preferably at least 85 MU, and in particular at least 90 MU.

[0030] Preferably, the Mooney viscosity ML1+4 at 100°C is at most 155 MU, preferably at most 150 MU, more preferably at most 145 MU, still more preferably at most 140 MU, yet more preferably at most 135 MU, even more preferably at most 130 MU, most preferably at most 125 MU, and in particular at most 120 MU.

[0031] Preferably, the Mooney viscosity ML1+4 at 100°C is within the range of from 65 MU to 140 MU, preferably 70 MU to 135 MU, more preferably 75 MU to 130 MU, still more preferably 80 MU to 125 MU, and yet more preferably 85 MU to 120 MU.

[0032] The polydiene rubber according to the invention has a A5 value within the range of from 13° to 32°, determined by measuring the phase angle 5 by means of a rubber process analyzer (RPA) at 100°C in a frequency sweep from 0.01 Hz to 40 Hz and a deflection angle of 0.5° (shear amplitude of 6.98%), wherein A5 is the 5 value at 0.1 rad / sec minus the 5 value at 100 rad / s.

[0033] Preferably, the A5 value is at least 14°, preferably at least 15°, more preferably at least 16°, still more preferably at least 17°, yet more preferably at least 18°, even more preferably at least 19°, most preferably at least 20°, and in particular at least 21°.

[0034] Preferably, the A5 value is at most 31°, preferably at most 30°, more preferably at most 29°, still more preferably at most 28°, yet more preferably at most 27°, even more preferably at most 26°, most preferably at most 25°, and in particular at most 24°.

[0035] Preferably, the A5 value is within the range of from 19° to 32°; preferably 18° to 32°; more preferably 20° to 32°; still more preferably 21° to 32°; yet more preferably 22° to 32°; even more preferably 23° to 32°; most preferably 24° to 32°; and in particular 25° to 31°.

[0036] In preferred embodiments, the polydiene rubber according to the invention has a weight average molecular weight (Mw) of at most 1,600,000 g / mol, preferably at most 1,500,000 g / mol, more preferably at most 1,400,000 g / mol, still more preferably at most 1,300,000 g / mol, yet more preferably at most 1,200,000 g / mol, even more preferably at most 1,100,000 g / mol, most preferably at most 1,000,000 g / mol, and in particular at most 900,000 g / mol; determined by GPC according to EN ISO 11344 with polystyrene standard.

[0037] Preferably, the weight average molecular weight (Mw) is at most 800,000 g / mol, preferably at most 750,000 g / mol, more preferably at most 700,000 g / mol, still more preferably at most 650,000 g / mol, yet more preferably at most 600,000 g / mol, even more preferably at most 550,000 g / mol, most preferably at most 500,000 g / mol, and in particular at most 450,000 g / mol; determined by GPC according to EN ISO 11344 with polystyrene standard.

[0038] Preferably, the weight average molecular weight (Mw) is at least 175,000 g / mol, preferably at least 200,000 g / mol, more preferably at least 225,000 g / mol, still more preferably at least 250,000 g / mol, yet more preferably at least 275,000 g / mol, even more preferably at least 300,000 g / mol, most preferably at least 325,000 g / mol, and in particular at least 350,000 g / mol; determined by GPC according to EN ISO 11344 with polystyrene standard. Preferably, the weight average molecular weight (Mw) is at least 350,000 g / mol, preferably at least 400,000 g / mol, more preferably at least 450,000 g / mol, still more preferably at least 500,000 g / mol, yet more preferably at least 550,000 g / mol, even more preferably at least 600,000 g / mol, most preferably at least 650,000 g / mol, and in particular at least 700,000 g / mol; determined by GPC according to EN ISO 11344 with polystyrene standard.

[0039] Preferably, the weight average molecular weight (Mw) is within the range of from 600,000 g / mol to 1,000,000 g / mol, preferably 650,000 g / mol to 950,000 g / mol, and more preferably 700,000 g / mol to 900,000 g / mol; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

[0040] Preferably, the weight average molecular weight (Mw) is within the range of from 300,000 g / mol to 500,000 g / mol, preferably 325,000 g / mol to 475,000 g / mol, and more preferably 350,000 g / mol to 450,000 g / mol; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

[0041] In preferred embodiments, the poly diene rubber according to the invention a number average molecular weight (Mn) of at most 800,000 g / mol, preferably at most 750,000 g / mol, more preferably atmost 700,000 g / mol, still more preferably at most 650,000 g / mol, yet more preferably at most 600,000 g / mol, even more preferably at most 550,000 g / mol, most preferably at most 500,000 g / mol, and in particular at most 450,000 g / mol; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

[0042] Preferably, the number average molecular weight (Mn) is at least 175,000 g / mol, preferably at least 200,000 g / mol, more preferably at least 225,000 g / mol, still more preferably at least 250,000 g / mol, yet more preferably at least 275,000 g / mol, even more preferably at least 300,000 g / mol, most preferably at least 325,000 g / mol, and in particular at least 350,000 g / mol; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

[0043] Preferably, the number average molecular weight (Mn) is within the range of from 300,000 g / mol to 500,000 g / mol, preferably 325,000 g / mol to 475,000 g / mol, and more preferably 350,000 g / mol to 450,000 g / mol; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

[0044] In preferred embodiments, the polydiene rubber according to the invention has a polydispersity index (PDI) of at least 1.10, preferably at least 1.15, more preferably at least 1.20, still more preferably at least 1.25, yet more preferably at least 1.30, even more preferably at least 1.35, most preferably at least 1.40, and in particular at least 1.45; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

[0045] Preferably, the polydispersity index (PDI) is at most 2.20, preferably at most 2.10, more preferably at most 2.00, still more preferably at most 1.90, yet more preferably at most 1.80, even more preferably at most 1.70, most preferably at most 1.60, and in particular at most 1.50; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

[0046] Preferably, the polydispersity index (PDI) within the range of from 1.20 to 1.80, preferably 1.30 to 1.70, more preferably 1.40 to 1.60; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

[0047] In preferred embodiments, the polydiene rubber according to the invention has a vinyl content within the range of from 26.0 wt.-% to 35.0 wt.-%, preferably 27.0 wt.-% to 34.0 wt.-%, more preferably 28.0 wt.-% to 33.0 wt.-%, still more preferably 29.0 wt.-% to 32.0 wt.-%, and yet more preferably 30.0 wt.-% to 31.0 wt.-%; determined according to ISO 12965:2000.Repeating units:

[0048] The poly diene rubber according to the invention comprises repeating units derived from at least one aliphatic conjugated diene monomer.

[0049] Preferably, the at least one aliphatic conjugated diene is a C4-25 aliphatic conjugated diene; preferably 1,3-butadiene.

[0050] In preferred embodiments, the polydiene rubber according to the invention comprises repeating units derived from at least one copolymerizable vinylaromatic comonomer; preferably selected from styrene, ortho-methyl styrene, meta-methyl styrene, para-methyl styrene, para-tertbutyl styrene and combinations thereof; preferably styrene.

[0051] In preferred embodiments, the poly diene rubber according to the invention has a styrene content within the range of from 5.0 wt.-% to 20.0 wt.-%, preferably 5.5 wt.-% to 19.0 wt.-%, more preferably 6.0 wt.-% to 18.0 wt.-%, still more preferably 6.5 wt.-% to 17.0 wt.-%, yet more preferably 7.0 wt.-% to 16.0 wt.-%, even more preferably 7.5 wt.-% to 15.0 wt.-%, most preferably 8.0 wt.-% to 14.0 wt.-%, and in particular 8.5 wt.-% to 13.0 wt.-%.Branching units (siloxane-based coupling agents)

[0052] The terms “branching units derived from at least one siloxane” and “siloxane-based coupling agents“, as used herein, may be used interchangeably.

[0053] The coupling agents according to the invention may contain at least 2 unsaturated siloxane units, preferably at least 2 to 20, more preferably from 3 to 15 and most preferably from 4 to 10 unsaturated siloxane units. Therefore, coupling agents according to the invention contain, in addition to -Si-O- units, at least two, preferably at least three, more preferably at least four units having at least one carboncarbon double bond, preferably vinyl groups (-CH=CH2groups). Typically, these units are connected to the silicon atom of the Si-O-unit. Therefore, these units are referred to herein as unsaturated siloxane units or “unsaturated -Si-0 units”. The coupling agents may be linear or branched, acyclic, cyclic for example monocyclic or polycyclic. Preferably they are cyclic, and preferably they have at least one cyclic structure, preferably a cyclic siloxane structure, i.e., a cyclic structure having at least one unsaturated -Si-O- unit as described above. Preferably, the siloxane-based coupling agents are cyclic and have a cyclic structure with at least two unsaturated siloxane units, more preferably at least three unsaturated siloxane units.

[0054] The coupling agents according to the invention preferably are used to couple poly diene rubbers, i.e., to link polymer chains with each other, preferably to create branched, for example multi-armed or star-shaped polymer architectures. The polymer coupling can be observed by an increase of molecular weight measured for example by GPC. The degree of coupling can be determined by comparing the chromatogram of the coupled polymer to the chromatogram of its precursor polymer. Upon coupling a high molecular weight fraction appears in the chromatogram. The ratio of the integral of the coupled fraction to the integral of the whole molecular weight distribution is the degree of coupling (weight % of polymer which is coupled).

[0055] An advantage of using the coupling agents according to the invention in the production of polydiene rubbers is that they allow to fine-tune the polymer structure. When the siloxane-based reagents are used in molar excess of their unsaturated units, with respect to polymer chains, the coupled polymer may contain unreacted unsaturated units from the coupling agent that may participate in a cross-linking(vulcanization) reaction. However, if the presence of unsaturated groups from the coupling agent in the polymer is not desired, their presence can be avoided or reduced by using the coupling agents in equimolar or submolar amounts (based on the molar ratio of unsaturated units of the coupling agent to polymer chains). In this case all unsaturated units of the coupling reagent can be expected to have been consumed by the coupling reaction. The molar amount of reactive polymer chains produced in the polymerization reaction can be assumed to be equivalent to the molar amount of polymerization initiator used in the polymerization reaction.

[0056] Preferably, the coupling agent according to the invention comprises from 2 to 20 unsaturated siloxane units, more preferably from 3 to 15 unsaturated siloxane units, still more preferably from 4 to 10 unsaturated siloxane units, corresponding to the general formula (1):(1),

[0057] In formula (1) each R1 independently represents an alkenyl group, preferably selected from the group consisting of vinyl (-CH=CH2), allyl (-CH-CH2-CH=CH2), n-propenyl (-CH2CH=CH2), n-butenyl (-CH2CH2CH=CH2), isobutenyl (-CH2(CH3)CH=CH2); n-pentenyl (-CH2CH2CH2CH=CH2), isopentenyl (-CH2(CH3)CH2CH=CH2, -CH2CH2(CH3)CH=CH2); and each R2 independently represents H, OH, or an organic residue, preferably having from 1 to 20 carbon atoms, and, optionally having one more heteroatoms selected from O, S, Si, N and / or a combination thereof. The hydrocarbon residue may be unsubstituted or substituted, where at least one hydrogen atom has been replaced by a substituent. Suitable substituents include siloxanes, polysiloxanes, silyls, aminosilyls, aminosiloxanes, alkylaminogroups, halogens and combinations thereof. Preferably, the hydrocarbon residue is aliphatic. Preferably, the hydrocarbon residue is selected from an alkenyl, preferably having from 2 to 10 carbon atoms, an alkyl preferably having from 1 to 10 carbon atoms, wherein the alkyl or alkenyl chain or both may be interrupted once or more than once by an ether oxygen atom, or R2 is selected from a siloxane or polysiloxane with up to 10 silicon atoms wherein the siloxane or polysiloxane may, optionally, have at least one silicone atom having at least one aliphatic substituent selected from alkyl, alkylene or alkenyl groups or a combination thereof. Preferably, at least one R2 represents methyl, or ethyl. Preferably all R2 represent methyl or ethyl or a combination thereof.

[0058] In a preferred embodiment of the invention the siloxane-based coupling agent contains at least one, preferably at least two, more preferably at least three units corresponding to the general formula (2):wherein R corresponds to R2 of formula (1) above. Preferably, R is selected from an alkyl having 1 to 10 carbon atoms and that may, optionally contain one more oxygen-ether atoms, and may be an alkoxy or polyalkoxy residue, or may, optionally contain one or more silanegroups, siloxane groups orpolysiloxane groups wherein the polysiloxane or siloxane groups may contain from 1 to 3 alkyl or alkenyl residue on the silicon atoms and the maximum number of silicon atoms, preferably, is less than 10. Preferably, R is a Ci-Cio-alkyl group, more preferably a Ci-C?-alkyl group and most preferably R is methyl.

[0059] In another preferred embodiment of the invention the unsaturated siloxane coupling agent is cyclic and corresponds to the formula (3)wherein n is 1 , 2, 3 or 4, preferably n is 1 or 2, and each R1 is as described in formula (1) and preferably at least one, more preferably all R1 represent a vinyl (-CH=CH2) group. Each R2 is as described in formula (1) above. Preferably at least one R2 is a Ci-C?-alkyl group and more preferably at least one R2 is methyl. Most preferably all R2 represent a methyl group.

[0060] In another preferred embodiment of the invention the unsaturated siloxane coupling agent corresponds to the general formula (4):wherein n is an integer of 1 to 20 and m is integer of 1 to 20, and each residue R is selected independently from each other and is as described for formula (2) above, andR3 is H, OH, a saturated or unsaturated hydrocarbon with 1 to 10 carbon atoms, a monovalent siloxane, polysiloxane or silane, or R3 connects to R5 to form a cyclic compound and represents a bivalent siloxane or polysiloxane with 1 to 10 silicon atoms and wherein one or at least one of the silicon atoms carries one or more alkyl or alkenyl residues having from 1 to 10 carbon atoms, or R3 and R5 jointly form a chemical bond to form a cyclic compound, andR4 is a linker group selected from (i) aliphatic hydrocarbons having from 1 to 20 carbon atoms that may optionally contain one or more oxygen ether groups, (ii) one or more silane or siloxane groups or combinations thereof, wherein one or more than one silicon atom may carry one or more aliphatic hydrocarbon groups having from 1 to 10 carbon atoms or a combination of (i) and (ii), andR5 is H, OH, a saturated or unsaturated hydrocarbon with 1 to 10 carbon atoms, a monovalent siloxane, polysiloxane or silane, or R5 is connected to R3 to form a cyclic compound and represents a bivalent siloxane or poly siloxane with 1 to 10 silicon atoms and wherein one or at least one of the silicon atoms carries one or more alkyl or alkenyl residues having from 1 to 10 carbon atoms, or R5 connects to R3 to form a cyclic compound and represents a bivalent siloxane or poly siloxane with 1 to 10 silicon atomsand wherein one or at least one of the silicon atoms carries one or more alkyl or alkenyl residues having from 1 to 10 carbon atoms, or R3 and R5 jointly form a chemical bond to form a cyclic compound.

[0061] In another preferred embodiment of the invention a polycyclic coupling agent is used. Suitable examples of polycyclic agents include those corresponding to formula (5):In formula (5) Ra, Rb, Rc, Rd, Re, Rf, Rg and Rh are identical or different from each other and are selected independently from each other a Ci-Cio-alkyl, a C2-Ce-alkenyl, a -O-Si-(R1’, R2’, R3’), wherein Rl’, R2’ and R3’ are selected independently from each other from a Ci-Cio-alkyl, a C2-C6- alkenyl, preferably vinyl, preferably at least one of Rl’, R2’ and R3’ comprises a vinyl unit, preferably all of Rl’, R2’ and R3’ are vinyl (-CH=CH2). At least one, preferably at least two, more preferably at least three of Ra, Rb, Rc, Rd, Re, Rf, Rg and Rh comprises a C2-Ce-alkenyl, preferably a vinyl (- CH=CH2). In one embodiment of a polycyclic coupling agent according to formula (5) at least four of Ra - Rh are vinyl or at least one of residues Ra - Rh is -O-Si(vinyl)3. In another embodiment of a compound according to formula (5) all of Ra - Rh are vinyl. Compounds according to formula (5) are also known as polyhedral oligomeric silsesquioxanes or POSS. The materials are commercially available or can be prepared as described, for example, in Quirk, Cheng et al in Macromolecules 2012, 45, 21, 8571-8579.

[0062] Preferably, the coupling agent according to the invention has a molecular weight of up to and including 5000 g / mol. Preferably the coupling agent has a molecular weight of less than 2000 g / mol.

[0063] Particularly preferred examples of coupling agents according to the invention include1,3,5,7-tetravinyl, 1,3,5,7-tetramethylcyclotetrasiloxane (V-D4),1,3,5-trivinyl, 1,3, 5 -trimethylcyclotrisiloxane (V-D3),octavinylsilasesquioxane, and substituted silasesquioxanes, wherein Ra is -O-Si(-CH=CH2)3, and residues Rb to Rg independently represent a Ci-C?-alkyl, preferably a cyclopentyl.

[0064] Combinations of one or coupling agents according to the invention may be used as well as combinations of one or more coupling agents of the invention with one or more other coupling agents.

[0065] Most particularly preferred examples of coupling agents according to the invention are1,3, 5,7, 9-pentavinyl-l, 3,5,7, 9-pentamethylcy- clopentasiloxane (V-D5)

[0066] Especially preferred is 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane (i.e. l,3,5-trivinyl-l,3,5- trimethylcyclotrisiloxane).Conjugated diene monomers and polydiene rubbers

[0067] In a preferred embodiment, the polydiene rubber comprises repeating units derived from at least one aliphatic conjugated diene monomer which comprises or consists of from 4 to 25, more preferably from 4 to 20 carbon atoms, still more preferably from 8 to 16 carbon atoms.

[0068] In another preferred embodiment, the polydiene rubber comprises repeating units derived from at least one aliphatic conjugated diene monomer which is 1,3-butadiene, isoprene, 1,3 -pentadiene, 2,3- dimethylbutadiene, l-phenyl-l,3-butadiene, 1,3 -hexadiene, myrcene, ocimene, or farnesene; preferably 1,3-butadiene.

[0069] In another preferred embodiment, the polydiene rubber comprises repeating units derived from at least two, three or four aliphatic conjugated diene monomers which are, independently from one another, 1,3-butadiene, isoprene, 1,3 -pentadiene, 2,3 -dimethylbutadiene, 1 -phenyl- 1,3 -butadiene, 1,3-hex- adiene, myrcene, ocimene, or famesene; preferably 1,3-butadiene.

[0070] In another preferred embodiment, the polydiene rubber comprises repeating units derived from at least one aliphatic conjugated diene monomer and at least one vinylaromatic comonomer.

[0071] Examples of suitable vinyl aromatic comonomers include, but are not limited to, styrene, orthomethyl styrene, meta-methyl styrene, para-methyl styrene, para-tertbutyl styrene, vinyl naphthalene, divinyl benzene, trivinyl benzene, divinyl naphthalene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene, a- methylstyrene, 2,4-diisopropyl-styrene and 4-tert-butylstyrene, stilbene, vinyl benzyl dimethylamine, (4-vinylbenzyl)dimethyl aminoethyl ether, N,N-dimethylaminoethyl styrene, tert-butoxystyrene, vi- nylpyridine or amino substituted derivatives (N,N-dimethylaminomethylstyrol) or copolymerizable vi- nylsilanes or multivinylsilanes with amino groups (e.g. l,4-bis[dimethyl(vinyl)silyl]piperazine), vinyl- aminodisiloxane or butadienylaminodisiloxane monomers such as 4-[3-(tert-butyl)-l,3,3-trimethyl-l-vi- nyldisiloxany Ijmorpholine, 3-(tert-buty l)-N,N-diethyl- 1 ,3 ,3 -trimethyl- 1 -vinyl-disiloxan- 1 -amine and 3 - (tert-butyl)-N,N -dibutyl- 1,3 ,3 -trimethyl- 1-vinyldisiloxan-l -amine and combinations thereof. Styrene is particularly preferred.

[0072] In another preferred embodiment, the polydiene rubbers comprise homopolymers and copolymers of 1,3-butadiene. Preferably, the polydiene rubbers according to the invention contain at least 51%by weight, preferably at least 60% by weight, based on the weight of the polydiene rubber, of units derived from 1,3 -butadiene. In one embodiment of the invention the polydiene rubbers contain at least 60% by weight, or at least 75% by weight units derived from 1,3 -butadiene.

[0073] In another preferred embodiment, the polydiene rubbers contain from 0 to 49% by weight, or from 0% to 40% by weight, based on the total weight of the poly diene rubber, of units derived from one or more comonomers.

[0074] In another preferred embodiment, the polydiene rubbers contain at least 60% by weight, or at least 70% by weight units derived from 1,3-butadiene and from 0 to 40% by weight, or from 0 to 30% by weight of units derived from one or more comonomers.

[0075] In another preferred embodiment, the polydiene rubbers contain from 0 to 20% by weight of units derived from one or more conjugated dienes other than 1,3-butadiene.

[0076] In another preferred embodiment, the polydiene rubbers contain up to 49% by weight of units derived from one or more vinylaromatic comonomer, preferably from 5 % to 40% by weight of units derived from one or more vinylaromatic comonomer. Preferably, the polydiene rubbers contain up to 49% by weight, based on the weight of the polymer, or from 0 to 40 % by weight, of units derived from styrene.

[0077] In another preferred embodiment, the polydiene rubbers comprises at least 75% or at least 95% by weight of units derived from one or more than conjugated diene monomers. In one embodiment the poly diene rubbers according to the invention comprise from 55% to 92% by weight of units derived from one or more conjugated diene monomers and from 5.8% to 45% by weight of units derived from vinyl aromatic comonomers.

[0078] Suitable copolymerizable comonomers further include one or more alpha-olefins, for example, ethene, propene, 1 -butene, 1 -pentene, 1 -hexene, 4-methyl-l -pentene, 1 -octene and / or combinations thereof.

[0079] In another preferred embodiment, the poly diene rubbers according to the invention contain from 0 to 20 % by weight of units derived from ethene, propene, 1 -butene, 1 -pentene, 1 -hexene, 4-methyl-l- pentene, 1 -octene and / or combinations thereof.

[0080] Suitable comonomers also include, but are not limited to, one or more other copolymerizable comonomers that introduce functional groups including cross-linking sites, branching sites, branches or functionalized groups. In a preferred embodiment, the diene polymers contain from 0% to 10% by weight or from 0% to 5% by weight of units derived from one or more of such other comonomers.

[0081] Combinations of one or more of the comonomers of the same chemical type as described above as well as combinations of one or more comonomers from different chemical types may be used.Functionalization

[0082] The polydiene rubbers may be additionally functionalized and may contain one or more functional groups, preferably an end group, containing, in addition to C and H atoms, at least one heteroatom selected from Si, S, N, O and / or a combination thereof. Such additionally functionalized polymers are obtainable by a reaction comprising reacting the reactive polymer chain ends with at least one functionalization reagent containing, in addition to C and H atoms, at least one heteroatom selected from Si, S, N, O and combinations thereof. The at least one functionalization reagent may be reacted with the polymer before, while or after, preferably after, reacting the polymer with the coupling agent. If necessary, the reaction product of the functionalization reaction may subsequently be treated to generate at least one -OH, -SH or -COOH group or a combination thereof or an anionic form thereof selected from -O', -S', -COO' groups and combinations thereof. Such treatment may include carrying out a hydrolysis reaction, for example by adding an alcohol or an acid, or includes a treatment with at least one other functionalization reagent that reacts with the first functionalization reagent to produce at least one -OH, -SH, or -COOH group or a combination thereof or an anionic form thereof selected from -O', -S', -COO'.

[0083] In preferred embodiments, the polydiene rubber according to the invention comprises functionalized units derived from at least one functionalization agent; preferably selected from a functionalization agent and co functionalization agents; more preferably comprising at least one group selected from anhydrides, carbamides, R3Si-, R3Si-N-, RaSi-O-. R3Si-S-, RN(H)-, -R2N- or combinations thereof, wherein each residue R represents independently -Ci- -alkyl or -OCi-12-alkyl; preferably -Ci-e-alkyl or -OCi-e-alkyl; wherein two residues R may be linked with each other to form a ring structure.

[0084] Preferred functionalization reagents are described hereinafter.Functionalization reagents

[0085] Functionalization reagents as known in the art may be used. Examples of functionalization agents include but are not limited to linear or branched alkoxy silanes and those described in US 2013 / 0281605 Al, US 2013 / 0338300 Al, US 2013 / 0280458 Al, US 2016 / 0075809 Al, US 2016 / 0083495 Al, WO 2021 / 009154 Al, US 4,894,409 and WO 2021 / 009156.Omega-functionalization :

[0086] Typically, functionalization agents capable for introducing functional groups at the terminal end of the polymer, i.e. at the omega position, are aliphatic compounds containing in addition to carbon and hydrogen atoms, heteroatoms selected from Si, O, S and N, preferably combinations of heteroatoms selected from Si and O, combinations of selected from Si, O and S, and combination of Si, O and N, or combinations of N and O. Typically, they lead, either directly or upon hydrolysis or reaction with another functional agent or both, to the polymer having at least one polar group selected from -OH, -COOH, -SH, -NR2H+, -NR3+, -NH3+or the respective ionic or non-ionic form and salts thereof and combinations thereof. Preferably, R represents, independently, an organic residue having from 1 to 12 carbon atoms, preferably alkyl groups. Typically, the functionalization agent has a molecular weight ofless than 5,000 g / mole or even less than 2,000 g / mole. Typically, the functionalization agents are not comonomers.

[0087] Preferred functionalization agents include linear or branched alkoxysilanes, linear or branched silanes and the reagents selected from the group consisting of:and combinations thereof.

[0088] In one embodiment the functionalization reagent is a linear or branched silane or siloxane. In another embodiment of the invention the functionalization reagent is a cyclic reagent. In one embodiment of the invention the functionalization reagent is cyclic and has a 4- to 7-membered aliphatic cyclic ring, more preferably 5- or 6-membered aliphatic cyclic ring wherein the ring either has at least 2, preferably at least 3 carbon atoms and at least one heteroatom selected from N, O, S, Si or a combination thereof. In another embodiment of the invention the functionalization reagent is cyclic and has a 3- to 20-membered cyclic structure wherein the ring has at least two, preferably at least three -Si(RlR2)-O- units, wherein R1 and R2 are, independently from each other, selected from H, a Ci-Cio saturated hydrocarbon residue that, optionally, may contain one or more heteroatoms selected from O, N, S, Si or a combination thereof. Preferably, R1 and R2 are selected from methyl, ethyl, propyl and butyl.

[0089] Functionalization reagents according to formula (6):

[0090] Reagents according to formula (6) include cyclosiloxane-based functionalization reagents. In formula (6) R1 and R2 are the same or different and correspond to H, Ci-Cio saturated hydrocarbon residue, preferably methyl, ethyl, propyl and butyl, and wherein the Ci-Cio saturated hydrocarbon residue, optionally, contains one or more heteroatoms selected from O, N, S, Si or a combination thereof, and n is an integer selected from 3 to 10, preferably 4 to 6. Specific examples of reagents according to formula (6) include but are not limited to hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane, reagents according to formula (6) can lead directly or indirectly (for example via a subsequent hydrolysis) to silanol (-Si(Rl)(R2)-OH) or silanolate (-Si(Rl)(R2)-O-) groups) as described, for example in US 2016 / 0075809 Al.

[0091] Functionalization reagents according to formula (7):

[0092] Reagents according to formula (7) include silalactone-based functionalization reagents. In formula (7) R1 and R2 are the same or different and are each selected from H or a residue having from 1 to 20 carbon atoms, preferably selected from alkyls, alkoxys, cycloalkyls, cycloalkoxys, aryls, aryloxys, alkaryls, alkaryloxy, aralkyls, or aralkoxys; R3, R4 are the same or different and are each selected from H or a residue having from 1 to 20 carbon atoms, preferably from alkyl, cycloalkyl, aryl, alkaryl or aralkyl, A is a divalent organic radical, preferably having from 1 to 26 carbon atoms, and which may, in addition to hydrogen atoms, comprise heteroatoms selected from O, N, S and Si.

[0093] Preferably Rl, R2 are the same or different and are selected from H, a (Ci-C24)-alkyl, a (Ci- C24)-alkoxy, a (C3-C24) -cycloalkyl, a (C3-C24)-cycloalkoxy, a (Ce-C24)-aryl, a (Ce-C24)-aryloxy, a (Ce- C24)-alkaryl, a (Ce-C24)-alkaryloxy, a (Ce-C24)-aralkyl or a (Ce-C24)-aralkoxy radical which, optionally, may contain one or more heteroatoms selected from O, N, S or Si. Preferably R3, R4 are the same or different and are each selected from H, a (Ci-C24)-alkyl, a (C3-C24)-cycloalkyl, a (Ce-C24)-aryl, a (Ce- C24)-alkaryl or a (Ce-C24)-aralkyl radical, optionally containing one or more heteroatoms, selected from O, N, S or Si.

[0094] In one embodiment of the invention A is represented by:-Xn-(CYlH)m-(CY2Y3)o-(CYlH)p- where n is 1 or 0, m is 1, 2, 3 or 4, o is 0, 1 or 2, p is 0, 1 or 2, preferably the sum of n, m, o and p is 2 or 3; X is O, S, NR, where R is H or C1-C3 alkyl or X is N(Si(alkyl)3), wherein each “alkyl” independently from each other represents a Ci to Ce alkyl, -oxyalkyl or alkoxy; Y1 is H or C1-C3 alkyl, Y2 is H or C1-C3 alkyl, Y3 is H or C1-C3 alkyl, preferably at least one of Y2 and Y3 is H.

[0095] Specific, non-limiting-examples of A include:-CH2-; -CH2CH2-; -CH2CH2CH2-; -C(CH3)-CH2-; -CH2-C(CH3)-CH-; -CH(CH3)-C(CH3)H-; -CH(CH3)- CH2-C(CH3)H-; -CH2-C(CH3)H-C(CH3)H-; -CH(CH3)-C(CH3)H-CH2-; -O-CH2-; -O-CH2CH2-; -O- CH2CH2-CH2-; -O-C(CH3)H-; -O-CH2CH2-; -O-C(CH3)H-CH2-;-O-CH2-C(CH3)H-; -O-CH2-C(CH3)H-CH2-; -O-CH2CH2-C(CH3)H-; -O-C(CH3)H-CH2-CH2-; -S-CH2- ; -S-CH2CH2-; -S-CH2CH2-CH2-; -S-C(CH3)H-; -S-CH2CH2-; -S-C(CH3)H-CH2-; -S-CH2-C(CH3)H-; - S-CH2-C(CH3)H-CH2-; -S-CH2CH2-C(CH3)H-; -S-C(CH3)H-CH2-CH2-;-NH-CH2-; -NH-CH2CH2-; -NH-CH2CH2-CH2-; -NH-C(CH3)H-CH2-; -NH-CH2-C(CH3)H-; -NH-CH2- C(CH3)H-CH2-; -NH-CH2CH2-C(CH3)H-; -NH-C(CH3)H-CH2-CH2-;-N(CH3)-CH2-; -N(CH3)-CH2-; -N(CH3)-CH2CH2-; -N(CH3)-CH2CH2-CH2-;-N(CH3)-C(CH3)H-CH2-; -N(CH3)-CH2-C(CH3)H-; -N(CH3)-CH2-C(CH3)H-CH2-;-N(CH3)-CH2CH2-C(CH3)H-; -N(CH3)-C(CH3)H-CH2-CH2-;N(Si(alkyl)3)-CH2-; -N(Si(alkyl)3)-CH2CH2-; N(Si(alkyl)3)-CH2CH2CH2-;-N(Si(alkyl)3)-C(CH3)H-; -N(Si(alkyl)3)-CH2CH2-; -N(Si(alkyl)3)-C(CH3)H-CH2-;-N(Si(alkyl)3)-CH2-C(CH3)H-; -N(Si(alkyl)3)-CH2-C(CH3)H-CH2-;-N(Si(alkyl)3)-CH2CH2-C(CH3)H-; -N(Si(alkyl)3)-C(CH3)H-CH2-CH2-.

[0096] Examples of reagents according to formula (7) include:2.2-dimethyl-l-oxa-2-silacyclohexan-6-one, 2,2,4-trimethyl-l-oxa-2-silacyclohexan-6-one, 2,2,5-tri- methyl-l-oxa-2-silacyclohexan-6-one, 2,2,4,5-tetramethyl-l-oxa-2-silacyclohexan-6-one, 2,2-diethyl- 1 -oxa-2-silacyclohexan-8-one, 2,2-diethoxy- 1 -oxa-2-silacy clohexan-6-one, 2,2-dimethyl- 1 ,4-dioxa-2- silacyclohexan-6-one, 2,2,5-trimethyl-l,4-dioxa-2-silacyclohexan-6-one, 2,2,3,3-tetramethyl-l,4-di- oxa-2-silacyclohexan-6-one, 2,2-dimethyl- l-oxa-4-thia-2-silacyclohexan-6-one, 2,2-diethyl-l-oxa-4- thia-2-silacyclohexan-6-one, 2,2-diphenyl-l-oxa-4-thia-2-silacyclonexan-6-one, 2-methyl-2-ethenyl-l- oxa-4-thia-2-silacyclohexan-6-one, 2,2,5-trimethyl-l-oxa-4-thia-2-silacyclohexan-6-one, 2,2-dimethyl- l-oxa-4-aza-2-silacyclohexan-6-one, 2,2,4-trimethyl-l-oxa-4-aza-2-silacyclohexan-6-one, 2,4-dime- thyl-2-phenyl-l-oxa-4-aza-2-silacyclohexan-6-one, 2,2-dimethyl-4-trimethylsilyl-l-oxa-4-aza-2-si- lacyclohexan-8-one, 2,2-diethoxy-4-methyl-l-oxa-4-aza-2-silacyclohexan-6-one, 2,2,4,4-tetramethyl- l-oxa-2,4-disilacyclohexan-8-one, 3,4-dihydro-3,3-dimethyl-lH-2.3-benzoxasilin-l-one, 2,2-dimethyl- l-oxa-2-silacyclopentan-5-one, 2,2,3-trimethyl-l-oxa- 2-silacyclopenten-5-one, 2,2-dimethyl-4-phe- nyl-l-oxa-2-silacyclopentan-5-one, 2,24(tert-butyl)-l-oxa-2-silacyclopentan-5-one, 2-methyl-2-(2-pro- pen-l-yl)-l-oxa-2-silacyclopentan-5-one, l,l-dimethyl-2,l-benzoxasilol-3(lH)-one, 2,2-dimethyl- 1- oxa-2-silacycloheptan-7-one.

[0097] Reagents according to formula (7) are described, for example, in US 2016 / 0075809 Al, in particular in

[0034] -

[0042] thereof, the use of such a reagent alone or by adding it to another functionalization reagent, for example a reagent according to formula (6) can lead to the creation of silacarboxylate groups, for example groups according to the general formula -Si(Rl)(R2)-C(R3)(R4)-A-COO-.

[0098] Functionalization reagents according to formula (8):

[0099] Reagents according to formula (8) include oxasilacycloalkanes. In formula (8) Rl, R2, R3, R4 and A are the same as described for formula (7). Examples of specific reagents according to formula (8) include:2.2-dimethyl-l-oxa-2-silacyclohexane, 2,2-diethyl-l-oxa-2-silacyclohexane,2.2-dipropyl-l-oxa-2-silacyclohexane, 2-methyl-2-phenyl-l-oxa-2-silacyclohexane, 2,2-diphenyl-l- oxa-2-silacyclohexane, 2,2,5,5-tetramethyl-l-oxa-2-silacyclohexane,2,2,3-trimethyl-l-oxa-2-silacyclohexane, 2,2-di methyl- l-oxa-2-silacyclopentane, 2,2,4-trimethyl-l- oxa-2-silacyclopentane, 2,2-dimethyl- 1 ,4-dioxa-2-silacyclohexane, 2, 2,5,5-tetramethyl-l ,4-dioxa-2,5- disilacyclohexane, 2,2,4-trimethyl-l-oxa-4-aza-2-silacyclohexane, benzo-2,2-dimethyl-l ,4-dioxa-2-si- lacyclohexane, benzo-2,2,4-trimethyl-l-oxa-4-aza-2-silacyclohexane. Reagents according to formula(8) are described, for example in US 2013 / 0281605 Al. The use of reagents according to formula (8) may lead to carbinol groups corresponding to the formula -S(R1)(R2)-C(R3)(R4)-A-OH.

[0100] Functionalization reagents according to formula (9):

[0101] In formula (9) x is an integer selected from 1, 2 and 3; R1 and R2 are independently of one another selected from -Ci-24-alkyl; preferably methyl or ethyl; more preferably methyl; R3 is a linear or branched or cyclic hydrocarbon group which contains one or more heteroatoms, preferably independently of one another selected from Si, N, O and S; preferably a Ci-Cio saturated hydrocarbon residue which contains one, two, three or four heteroatoms independently of one another selected from Si, N, O and S. In preferred embodiment, R3 is selected from -CH2CH2-R4, -CH2CH2CH2-R4, and -CH2CH2CH2CH2-R4, wherein R4 means -N(Si(Ci-4-alkyl))2, preferably -N(Si(CH3)3)2; -N(Ci-4)alkyl)2, preferably -N(CH3)2; -S-Si(Ci-4alkyl)3, preferably -S-Si(CH3)2C(CH3)3; or2,2-dimethoxy-azasilolidinyl.

[0102] Preferred reagents according to general formula (9) are according to formulas (9a) to (9f):

[0103] These reagents are commercially available.

[0104] Functionalization reagents according to formula (10):

[0105] The reagents according to formula (10) include cyclic ureas. In formula (10) R3 represents a divalent, saturated or unsaturated, linear or branched, preferably aliphatic, hydrocarbon group having from 1 to 20 carbon atoms which, in addition to C and H, may contain one or more heteroatoms, preferably independently of one another selected from O, N, S or Si. Preferably R3 corresponds to the general formula (11):-[CHX^-fCHX tO tCHX3],- (11) wherein z is 1 or 0; o, p and q are independently selected from 0, 1 and 2 with the proviso that at least one of o, p and q is not 0. X1, X2and X3are independently selected from H and linear or branched alkyl, alkylaryl and aryl groups having from 1 to 12 carbon atoms and from aminoalkyl (N-R) groups wherein R is a linear or branched or cyclic alkyl or alkylaryl residue having from 1 to 12 carbon atoms, and X1and X2may represent a chemical bond between to form a carbon-carbon bond to provide an unsaturationin the carbon chain, o, p, q, X1, X2and X3are selected such that the total number of carbon atoms is not more than 20.

[0106] In one embodiment R3 is selected from substituted alkylenes, for example from substituted alkylenes corresponding to formula (11) wherein at least one of X1, X2and X3is not H.

[0107] In one embodiment R3 is selected from unsubstituted alkylenes, for example from unsubstituted alkylenes corresponding to formula (11) wherein all of X1, X2and X3are H. In a preferred embodiment R3 corresponds to -[(CH)2]n-, wherein n is an integer from 1 to 5, preferably 1 to 3, more preferably 1 or 2.

[0108] In one embodiment R3 is selected from unsaturated substituted or unsubstituted alkylenes and, for example, corresponds to formula (Ila) wherein X1and X2together form a carbon-carbon bond. Specific examples of unsaturated alkylenes include but are not limited to -CH=CH- or -CH2-CH=CH-.

[0109] In formula (10) R1 and R2 are identical or different and represent saturated or unsaturated hydrocarbon groups having from 1 to 20 carbon atoms and wherein the hydrocarbon group may contain, in addition to C and H atoms, one or more heteroatoms, preferably selected from the group consisting of O, N, S and Si. For example, R1 and R2 may be identical or different and are selected from -(Ci- C2o)-alkyl, -(C3-C2o)-cycloalkyl, -(Ce-C2o)-aryl, -(Ce-C2o)- alkaryl or -(Ce-C2o)-aralkyl radicals which may contain one or more heteroatoms, preferably independently selected from O, N, S or Si. Preferably R1, R2 are selected independently from each other from methyl, ethyl, n-propyl, isopropyl, n-butyl, secbutyl, tert-butyl, trialkyl silyl with alkyl groups of 1 to 4 carbon atoms per alkyl group, phenyl and phenyls independently substituted with one, two or three methyl-, ethyl-, propyl, and / or- butyl residues.

[0110] Preferred specific examples of agents according to formula (10) include but are not limited to: 1 ,3 -dimethy 1-2-imidazolidinone, 1 ,3 -diethy 1-2-imidazolidinone, 1 -methy 1-3 -phenyl-2-imidazolidinone, l,3-diphenyl-2-imidazolidinone, 1, 3, 4-trimethy 1-2-imidazolidinone, l,3-bis(trimethylsilyl)-2-imidazol- idinone, l,3-dihydro-l,3-dimethyl-2H-imidazol-2-one, tetrahydro- l,3-dimethyl-2(lH)-pyrimidinone, tetrahydro- l-methyl-3-phenyl-2(lH)-pyrimidinone, tetrahydro-l,3,5-trimethyl-2(lH)-pyrimidinone, tetrahydro-3, 5 -dimethy 1-4H-1, 3, 5-oxadiazin-4-one, tetrahydro-1 ,3,5-trimethyl- 1 ,3,5-triazin-2(l HQ- one, hexahydro-1, 3-dimethyl-2H-l,3-diazepin-2-one. A particularly preferred example is 1,3-dimethyl- 2-imidazolidinone, also referred to as DMI, i.e. R3 is -CH2-CH2- and / or R1 and R2 are both -CH3.

[0111] Reagents according to formula (10) are described, for example, in US 4,894,409, and international patent applications WO 2021 / 009154 and WO 2021 / 009156.

[0112] The functionalization reagents described above can react with reactive chain ends of the polymer and are therefore also referred to herein as “omega-functionalization reagents.” Instead of or in addition to adding the omega-functionalization reagents, “alpha-functionalization agents” may be added at the beginning of the polymerization, for example as functionalized initiators. This typically leads to alpha-functionalized polymers, i.e., polymers with polar groups at the beginning of the chain. Examples of alpha-functionalization reagents are described in EP 2 847264 Al and EP 2 847 242 Al.

[0113] In case the polymerization reaction is not terminated by the reaction with the coupling reagent, or by the optional reaction with the one or more omega-functionalization agents described above, the polymerization reaction may be terminated, for example by quenching. Quenching agents known in the art may be used. Typical quenching agents for terminating the polymerization include alcohols, for example octanol.A Ipha-functionalization :

[0114] To prepare alpha-functionalized polymers the polymers may be prepared as described above except that one or more alpha-functionalization agent is used. The alpha-functionalization agent is used prior to step (b), typically the functionalization reagent is used at the beginning of the polymerization reaction, i.e., at step (a), preferably at the beginning of step (a). Typically, alpha-functionalizing agents include aliphatic compounds comprising in addition to carbon and hydrogen atoms, heteroatoms selected from Si, O, S and N, and combinations thereof. Typical alpha-functionalizing agents have a molecular weight of up to 5,000 g / mol or less than 2,000 g / mol.

[0115] Alpha-functionalization agents include functional initiators carrying the functional group or a precursor thereof, for example a protected group that can be deprotected by hydrolyzation or otherwise, for example during work up or during compounding to make a rubber compound. Functional initiators include, for example, salts of organic anions of tertiary amines or cyclic amines where the nitrogen atom forms part of the aliphatic ring structure. An example of a tertiary amine containing functional initiator is represented bywhere R3 and R4 are the same or different and are organic residues having from 1 to 20 carbon atoms, preferably selected from linear or branched alkyls, silyl-substituted alkyls, and silyls, wherein R3 and R4 may be connected form a ring structure. R2 preferably is a linear or branched Ci- to C2o-alkyl or silyl-substituted alkyl group that carries a negative charge. Further examples include but are not limited to linear or cyclic amide initiators, for example salts of aliphatic amines having 4, 5, 6 or 7 carbon atoms and at least one nitrogen atom carries a negative charge. The ring may be unsubstituted or substituted once or more than once, preferably by a Ci - to C2o-alkyl substituent. Specific examples of cyclic amide initiators include, but are not limited to:

[0116] Functional initiators also include active reaction products of one or more initiator and one or more functionalized monomers. The functionalized monomer carries at least one functional group or a precursor thereof. The functionalized monomers may be used in equimolar amounts with respect to the initiator or in excess or the initiators may be used in molar excess compared to functionalized monomers. Examples of functionalized monomers include but are not limited to dienes, aliphatic and aromatic vinyls that are functionalized to carry one or more functional groups, for example trialkylamino groups, aminosilane groups, or alkoxy groups that can be hydrolyzed into hydroxy groups, or thioalkyl groups that can be hydrolyzed into thiol groups. Specific examples of functionalized aromatic vinyl compounds include but are not limited to trialkylaminostyrenes, for example those represented by (Rl)(R2)N(R3)x- Ph-CH=CH2where x represents 1, 2, 3, 4 or 5, preferably 1, 2 or 3, and R1 , R2, and R3, preferably represent independently from each other a Ci to C20 alkyl group or alkylsilylgroups. R1 and R2 can be connected to form a ring. Further examples of functionalized aromatic vinyls include those represented bywhere R1 and R2 represent a functional group containing at least two selected from the group consisting of carbon, hydrogen, and silicon. Examples include hydrocarbon-based functional groups (functional groups containing carbon and hydrogen) such as methyl and ethyl groups which may be used as phenol- protecting groups, and silicon-based functional groups (functional groups containing carbon, hydrogen, and silicon) such as trimethylsilyl and triethoxysilyl groups. Preferred among these are hydrocarbonbased functional groups, preferably alkyl groups. The number of carbon atoms in the alkyl groups is preferably 1 to 6, more preferably 1 to 4, still more preferably 1 to 2. Preferably at least one of R1 or R2 is branched. Examples of recent publications concerning alpha-functionalization include US 2021 / 230416 Al and EP 3 733 718 Al.

[0117] Mixtures of different functionalized initiators or mixtures of functionalized and nonfunctionalized initiators may be used also.Methods of preparation

[0118] The homo- or copolymers of the invention can be prepared by methods known in the art. The polymerization may be carried out to produce a statistical polymer, also called random copolymer, a block-copolymer, a gradient copolymer or combinations of them and include linear and branched architectures as known by the person skilled in the art.

[0119] The polymers can be obtained by a process comprising an anionic polymerization or a catalytic polymerization using one or more coordination catalysts. Coordination catalysts in this context include Ziegler-Natta catalysts or monometallic catalyst systems. Preferred coordination catalysts are those based on Ni, Co, Ti, Zr, Nd, V, Gd, Cr, Mo, W or Fe. Preferably the polymerization reaction comprises an anionic solution polymerization. Initiators for anionic solution polymerization include organometals, preferably based on alkali or alkaline earth metals. Examples include but are not limited to methyllithium, ethyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, pentyllithium, n-hexyllithium, cyclohexyllithium, octyllithium, decyl-lithium, 2-(6-lithio-n-hexoxy)tetrahydropyran, 3-(tert-butyldime- thylsiloxy)-! -propyllithium, phenyllithium, 4-butylphenyllithium, 1 -naphthyllithium, p-toluyllithium and allyllithium compounds, derived from tertiary N-allylamines such as [l-(dimethylamino)-2-pro- penyl]lithium, [l-[bis(phenylmethyl)amino]-2-propenyl]lithium, [l-(diphenylamino)-2-propenyl]lith- ium, [1 -(1 -pyrrolidinyl)-2-propenyl]lithium, lithium amides of secondary amines such as lithium pyr- rolidide, lithium piperidide, lithium hexamethylene imide, lithium 1 -methyl imidazolidide, lithium 1- methyl piperazide, lithium morpholide, lithium dicyclohexylamide, lithium dibenzyl amide, lithium diphenyl amide. The allyllithium compounds and the lithium amides can also be prepared in situ by reacting an organolithium compound with the respective tertiary N-allylamines or with the respective secondary amines. Di- and polyfunctional organolithium compounds can also be used, for example 1,4- dilithiobutane, dilithium piperazide. Preferably n-butyllithium, sec-butyllithium or a combination thereof are used. The initiator creates anionic, reactive monomers and the polymerization propagates by the reaction of the reactive carbanionic monomers with other monomers which creates reactive carbanionic polymer chain ends. In case of a polymerization using one or more coordination catalysts, the reactive chain ends are produced by the catalyst.

[0120] Randomizers and control agents as known in the art can be used in the polymerization for controlling the structure of the polymer, in particular for avoiding aggregations or for increasing random structures. Such agents include, for example, diethyl ether, di-n-propylether, diisopropyl ether, di-n- butylether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-butyl ether, ethylene glycol di-tert-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butyl ether, diethylene glycol di-tert-butyl ether, 2-(2-ethoxyethoxy)-2-me- thyl-propane, triethylene glycol dimethyl ether, tetrahydrofuran, ethyltetrahydrofurfuryl ether, hexyltet- rahydrofurfuryl ether, 2,2-bis(2-tetrahydrofuryl)propane, dioxane, trimethylamine, triethylamme, N,N,N,N-tetramethyl-ethylenediamine, N-methylmorpholine, N-ethylmorpholine, 1,2-dipiperidi- noethane, 1,2-dipyrrolidinoethane, 1,2-dimorpholinoethane, potassium and sodium salts of alcohols, phenols, carboxylic acids, sulphonic acids and combinations thereof. In one embodiment of the invention the polymer is a random polymer and, preferably, at least one randomizer is used in the polymerization reaction.

[0121] In one embodiment of the invention the polymer is a random polymer. In one embodiment the polymer is a block-copolymer. For the generation of block copolymers, the polymerization is preferablystarted with one monomer and subsequently, depending on the size of the blocks to be performed the other (co)monomer(s) are added. The sequence of monomer additions can be adapted depending on which blocks of different monomers are desired to be created. In one embodiment of the invention such a block is created at the beginning or at the end of the polymerization or both.

[0122] In one embodiment the polymerization is carried out in the presence of at least one solvent and preferably in solution. Preferred solvents for solution polymerizations include inert aprotic solvents, for example aliphatic hydrocarbons. Specific examples include, but are not limited to, butanes, pentanes, hexanes, heptanes, octanes, decanes and cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, 1,4-dimethylcyclohexane and combinations thereof and including isomers thereof. Further examples include alkenes such as 1 -butene or aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene, diethylbenzene or propylbenzene and combinations thereof. These solvents can be used individually or as mixtures. Preferred solvents include cyclohexane, methylcyclopentane and n-hexane. The solvents may also be mixed with polar solvents if appropriate.

[0123] The polymerization can be carried out by first introducing the (co)monomers and solvent and then starting the polymerization by adding initiator or catalyst. The polymerization may also be carried out in a feed process where the polymerization reactor is filled by adding monomers and solvents. The initiator or catalyst are introduced or added with the monomers and solvent. Variations may be used, such as introducing the solvent in the reactor, adding initiator or catalyst followed by adding the monomers. The polymerization can be carried out in a continuous mode or batchwise. Further monomer and solvent may be added during or at the end of the polymerization.

[0124] The polymerization can be carried out at normal pressure or at elevated pressure (for example, from 1 to 10 bar) or at reduced pressure. Typical reaction temperatures include room temperature but depending on the nature and amounts of comonomers the reaction temperature may be above or below room temperature. Typical ranges include, for example from -12°C to 140°C in a continuous adiabatic process, or from 50 to 120°C in a batch process.

[0125] The polymerization reaction leads to reactive polymer chain ends, preferably anionic chain ends. The polymerization mixture or solution containing reactive polymer chain ends is contacted with at least one of the siloxane-based coupling agents according to the invention at the desired progression of the polymerization reaction, for example when the desired conversion rate or the desired molecular weight range of the polymer has been reached. Typically, it is desired to carry out the coupling reaction at the end of the polymerization reaction, for example after at least 90%, or at least 95% of the monomers have been consumed. For example, the coupling agent may be added before or after the monomer feed has been stopped or discontinued. The coupling agent may be added as pure substance or as solution or dispersion. Although not preferred and not necessary, coupling agents other than the unsaturated siloxanes according to the invention may be used in addition. Typically, the addition of the coupling agent is carried out at a reaction temperature of 20°C to 130°C, or from 50°C to 130°C.

[0126] Another advantage of using the siloxane-based coupling agents for producing diene rubber is that the polymers obtained by using them can still be functionalized to produce diene rubbers with additional functional groups, preferably end groups. Therefore, the method according to the invention may further comprises the step reacting the polymer with at least one functionalization agent for introducing at least one functional group to the polymer, wherein this step may be carried out before, after or during step (ii). Typically, such functionalization reagents are aliphatic compounds containing in addition to carbon and hydrogen atoms, heteroatoms selected from Si, O, S and N, preferably combinations of heteroatoms selected from Si and O, combinations of selected from Si, O and S, and combination of Si, O and N, or combinations of N and O. Typically, they lead, either directly or upon hydrolysis or reaction with another functional agent or both, to the polymer having at least one polar group selected from -OH, -COOH, -SH or salts thereof and combinations thereof. Typically, the functionalization agent has a molecular weight of less than 5,000 g / mole or even less than 2,000 g / mole.

[0127] The manufacture of rubbers is well known in the industry and described for example in the Handbook of Synthetic Rubber, for rubbers in general in Chapter 5, pages 67 - 86, specially for SSBR Chapter 9, pages 173 -193 and specifically for HNBR Chapter 14, pages 295 - 314, ARLANXEO Deutschland GmbH, Germany, 2020.

[0128] The monomers used for the polymerization are typically obtained from fossil sources, for example by cracking from crude oil but monomers obtained from a sustainable source may be used as well. Using monomers from a sustainable source has the advantage of lowering the carbon dioxide footprint of the polymers and the articles produced from them. Monomers obtained from a sustainable source include monomers obtained from a biological source including plants fungi or bacteria. Such monomers are chemically identical to monomers obtained from fossil sources but have a higher content of the carbon 14 isotope, by which they can be identified. Monomers obtained from a sustainable source also includes monomers obtained from recycled waste materials, including recycled biological waste material (for example wood pulp), recycled rubber waste materials (for example obtained from the pyrolysis of tires) and recycled plastic waste materials. Monomers obtained from recycled materials also include ISCC+ certified monomers, which may be used, for example, in a so-called mass-balanced process to reduce the overall CCL-content of the production chain (see for example, Pete Spanos et al, “Sustainable Keltan EPDM”, RUBBERWORLD.COM, April 2023, where the process is described for EPDM polymers but the principles set out there can be also applied to other polymers accordingly). Monomers from a sustainable source may or may not have to be purified differently than those obtained from fossil sources for providing monomers at the same degree of purity.

[0129] Preferably, a method of making a poly diene rubber according to the invention as described above comprises the steps of:(a) polymerizing the at least one aliphatic conjugated diene monomer to produce a polymer having reactive polymer chain ends;(b) reacting at least some of the reactive polymer chain ends with the at least one siloxane; and(c) optionally, introducing at least one functional group to the polydiene rubber by means of a functionalization agent, wherein optional step (c) is carried out before, after or during step (b).

[0130] Another aspect of the invention relates to a poly diene rubber obtained by the method according to the invention ass described above.

[0131] The polymers may be worked up and isolated as known in the art. Antioxidants as known in the art, such as sterically hindered phenols, aromatic amines, phosphites, thioethers, may be added to the reaction mixture. Preferably they are added before or during the working up of the polymers of the invention. Extender oils used for diene rubbers such as TDAE (Treated Distillate Aromatic Extract)-, MES (Mild Extraction Solvates)-, RAE (Residual Aromatic Extract)-, TRAE (Treated Residual Aromatic Extract)-, naphthenic and heavy naphthenic oils can be added to the reaction mixture prior or during work up for providing oil-extended rubbers. The solvent can be removed from the reaction mixture by conventional methods including distillation, stripping with steam or by applying a vacuum or reduced pressure, if necessary, at elevated temperatures. Typically, the solvent is recycled.

[0132] The polymer crumbs can be further dried on mills or processed on mills, for example into sheets, or compressed for example into bales.Rubber compounds

[0133] The polymers according to the invention can be used to produce rubber compounds. Rubber compounds can be prepared by a process comprising mixing at least one polymer according to the invention with at least one filler. The rubber compounds may be vulcanizable and further comprise one or more than one curing agent. The curing agent is capable of crosslinking (curing) the diene polymer and is also referred to herein as “crosslinker” or “vulcanization agent”. Suitable curing agents include, but are not limited to, sulfur, sulfur-based compounds, and organic or inorganic peroxides.

[0134] In a preferred embodiment of the invention the curing agent includes a sulfur. Instead of a single curing agent a combination of one or more curing agents may be used, or a combination of one or more curing agent with one or more curing accelerator or curing catalysts may be used. Examples of sulfur- containing compounds acting as sulfur-donors include but are not limited to sulfur, sulfur halides, dithiodimorpholine (DTDM), tetramethylthiuramdisulphide (TMTD), tetraethylthiuramdisulphide (TETD), and dipentamethylenthiuramtetrasulphide (DPTT). Examples of curing accelerators include but are not limited to amine derivates, guanidine derivates, aldehydeamine condensation products, thiazoles, thiuram sulphides, dithiocarbamates and thiophospahtes.

[0135] In another embodiment of the invention the curing agent includes a peroxide. Examples of peroxides used as vulcanizing agents include but are not limited to di-tert.-butyl-peroxides, di-(tert. -butylperoxy -trimethyl-cyclohexane), di-(tert.-butyl-peroxy-isopropyl-)benzene, dichloro-benzoylperoxide, dicumylperoxides, tert.-butyl-cumyl-peroxide, dimethyl-di(tert.-butyl-peroxy)hexane and dimethyl-di(tert.-butyl-peroxy)hexine and butyl-di(tert.-butyl-peroxy)valerate. A vulcanizing accelerator of sulfene amide-type, guanidine-type, or thiuram-type can be used together with a vulcanizing agent as required.

[0136] If added, the vulcanizing agent is typically present in an amount of from 0.5 to 10 parts by weight, preferably of from 1 to 6 parts by weight per 100 parts by weight of rubber.

[0137] The rubber compounds are suitable for making tires or components of tires such as sidewalls or tire treads. The tire or tire component will typically contain the rubber compound in is vulcanized form.

[0138] Conventional fillers can be used. Conventional fillers include silicas and carbon-based fillers, for example carbon blacks. The fillers can be used alone or in a mixture. In a particularly preferred form, the rubber compositions contain a mixture of silica fillers and carbon black. The weight ratio of silica fillers to carbon black may be from 0.01:1 to 50:1 , preferably from 0.05:1 to 20:1.

[0139] Preferably, the filler includes silica-containing particles, preferably having a BET surface area (nitrogen absorption) of from 5 to 1,000, preferably from 20 to 400 m2 / g. Such fillers may be obtained, for example, by precipitation from solutions of silicates or by flame hydrolysis of silicon halides. Silica- containing filler particles may have particle sizes of 10 to 400 nm. The silica-containing filler may also contain oxides of Al, Mg, Ca, Ba, Zn, Zr or Ti. Other examples of silicon-oxide based fillers include aluminum silicates, alkaline earth metal silicates such as magnesium silicates or calcium silicates, preferably with BET surface areas of 20 to 400 m2 / g and primary particle diameters of 10 to 400 nm, natural silicates, such as kaolin and other naturally occurring silicates including clay (layered silicas). Further examples of fillers include glass particle-based fillers like glass beads, microspheres, glass fibers and glass fiber products (mats, strands).

[0140] Polar fillers, like silica-containing fillers, may be modified to make them more hydrophobic. Suitable modification agents include silanes or silane-based compounds. Typical examples of such modifying agents include, but are not limited to compounds corresponding to the general formula (12):(RlR2R3O)3Si-R4-X (12) wherein each Rl, R2, R3 is, independently from each other, an alkyl group, preferably Rl, R2, R3 are all methyl or all ethyl, R4 is an aliphatic or aromatic linking group with 1 to 20 carbon atoms and X is sulfur-containing functional group and is selected from -SH, -SCN, -C(=O)S or a polysulfide group.

[0141] Instead of or in addition to silicas that have been modified as described above such modification may also take place in situ, for example during compounding or during the process of making tires or components thereof, for example by adding modifiers, preferably silanes or silane-based modifiers, for example including those according to formula (12), when making the rubber compounds.

[0142] Filler based on metal oxides other than silicon oxides include but are not limited to zinc oxides, calcium oxides, magnesium oxides, aluminum oxides and combinations thereof. Other fillers include metal carbonates, such as magnesium carbonates, calcium carbonates, zinc carbonates and combinationsthereof, metal hydroxides, e.g. aluminum hydroxide, magnesium hydroxide and combinations thereof, salts of alpha-beta-unsaturated fatty acids and acrylic or methacrylic acids having from 3 to 8 carbon atoms including zinc acrylates, zinc diacrylates, zinc methacrylates, zinc dimethacrylates and mixtures thereof.

[0143] In another embodiment of the invention the rubber compound contains one or more fillers based on carbon, for example one or more carbon black. The carbon blacks may be produced, for example, by the lamp-black process, the furnace-black process or the gas-black process. Preferably, the carbon back has a BET surface area (nitrogen absorption) of 20 to 200 m2 / g. Suitable examples include but are not limited to SAF, ISAF, HAF, FEF and GPF blacks.

[0144] Other examples of suitable filler include carbon-silica dual-phase filler, lignin or lignin-based materials, starch or starch-based materials and combinations thereof.

[0145] In a preferred embodiment, the filler comprises one or more silicon oxide, carbon black or a combination thereof.

[0146] Typical amounts of filler include from 5 to 200 parts per hundred parts of rubber, for example, from 10 to 150 parts by weight, or from 10 to 95 parts by weight for 100 parts by weight of rubber.

[0147] The rubber compounds may further contain one or more additional rubbers other than the diene rubbers according to the invention and one or more than one rubber additive. Additional rubbers include, for example, natural rubber and synthetic rubber. If present, they may be used in amounts in the range from 0.5 to 95 % by weight, preferably in the range from 10 to 80 % by weight, based on the total amount of rubber in the composition. Examples of suitable synthetic rubbers include BR (polybutadiene), acrylic acid alkyl ester copolymers, IR (poly isoprene), E-SBR (styrene-butadiene copolymers produced by emulsion polymerization), S-SBR (styrene-butadiene copolymers produced by solution polymerization), HR (isobutylene-isoprene copolymers), NBR (butadiene-acrylonitrile copolymers), HNBR (partially or completely hydrogenated NBR rubber), EPDM (ethylene-propylene-diene terpolymers) and mixtures thereof. Natural rubber, E-SBR and S-SBR with a glass temperature above -60 °C, polybutadiene rubber with a high cis content (> 90%) produced with catalysts based on Ni, Co, Ti or Nd, polybutadiene rubber with a vinyl content of up to 80% and mixtures thereof are of particular interest for the manufacture of automotive tires.

[0148] The rubber compounds may also comprise one or more rubber additive. Rubber additives are ingredients that may improve the processing properties of the rubber compositions, serve to crosslink the rubber compositions, improve the physical properties of the vulcanizates produced from the rubber, improve the interaction between the rubber and the filler or serve to bond the rubber to the filler. Rubber auxiliaries include, but are not limited to reaction accelerators, antioxidants, heat stabilizers, light stabilizers, ozone stabilizers, processing aids, plasticizers, tackifiers, blowing agents, dyes, pigments, waxes, extenders, organic acids, silanes, retarders, metal oxides, extender oils such as DAE (Distillate Aromatic Extract)-, TDAE (Treated Distillate Aromatic Extract)-, MES (Mild Extraction Solvates)-, RAE(Residual Aromatic Extract)-, TRAE (Treated Residual Aromatic Extract)-, naphthenic and heavy naphthenic oils as well as activators.

[0149] The total amount of rubber additives may range from 1 to 300 parts by weight, preferably from 5 to 150 parts by weight based on 100 parts by weight of total rubber in the composition.

[0150] The rubber compositions can be prepared with conventional processing equipment for making and processing of (vulcanizable) rubber compounds and include rollers, kneaders, internal mixers or mixing extruders. The rubber compositions can be produced in a single-stage or a multi-stage process, with 2 to 3 mixing stages being preferred. Cross-linking agents, for example sulfur, and accelerators may be added in a separate mixing stage, for example on a roller, with temperatures in the range of 30 °C to 90 °C being preferred. Crosslinking agent, for example sulfur, and accelerator are preferably added in the final mixing stage.Applications

[0151] The rubber compositions according to the invention can be used for producing rubber vulcanizates, in particular for producing tires, in particular tire treads.

[0152] Rubber vulcanizates can be obtained by providing a vulcanizable composition according to the invention and subjecting it to at least one curing reaction. The vulcanizable and I or the vulcanized rubber composition can be subjected to shaping prior, during or after the curing reaction. Shaping may be carried out by process steps including molding, extruding and a combination thereof.

[0153] The (vulcanizable) rubber compositions provided herein are also suitable for the manufacture of molded articles, for example for the manufacture of cable sheaths, hoses, drive belts, conveyor belts, roll linings, shoe soles, sealing rings and damping elements.

[0154] Another aspect of the invention relates to a molded article, in particular a component of a tire, for example a tire tread, or a complete tire, containing a vulcanized rubber composition obtained by vulcanizing a vulcanizable rubber composition according to the invention.Examples

[0155] The following examples further illustrate the invention but are not to be construed as limiting its scope. Examples marked as comp, examples are comparative examples.

[0156] Different cyclic vinyl siloxanes as coupling agent for S-SBRs were compared.Example 1 - preparation of branched poly diene rubbers with different coupling agents:

[0157] Methyl-vinyl-substituted siloxane derivatives with different ring sizes were investigated (V-D3 vs. V-D4 vs. V-D5). Additionally, a V-D4 derivative containing epoxide groups instead of vinyl groups was tested:

[0158] The following batch recipe was used as reference: 14 mmol butyl lithium (BuLi), 0.25 equivalents (relative to molar amount of BuLi) V-D4, and 1 equivalent of 2,2-dimethyl-l-oxa-4-thia-2-sila- cyclohexan-6-one (SL). This recipe was adjusted to obtain the same amount of siloxane units per BuLi. The poly diene rubbers were obtained via the following protocols:

[0159] Sample M - V-D3 (0,33 equivalents): An inert (nitrogen flushed) 20 L reactor was fdled with 8500 g hexane, 1,82 mmol 2,2'-(propane-2,2-diyl)bis(oxolane) (DTHFP) and 14 mmol n-butyllithium (BuLi) at 44 °C. 1335 g 1,3-Butadiene and 165 g styrene were added simultaneously, and an adiabatic polymerization was performed for 1 h. Subsequently, 4,62 mmol l,3,5-trivinyl-l,3,5-trimethylcyclo- trisiloxane (V-D3) was added to the living polymer solution and stirred for 20 min. Then, 14 mmol 2,2- dimethyl-l-oxa-4-thia-2-sila-cyclohexan-6-on was added and reacted for another 20 min. The reaction was terminated with n-octanol and stabilized with 0,3 phr Irganox 1520. The solvent was removed via steam-stripping and the final sample was dried at 60 °C under reduced pressure.

[0160] Sample K - V-D4 (0,25 equivalents)): This comparative Example was prepared as for Sample M, but 3.5 mmol l,3,5,7-tetravinyl-l,3,5,7-tetramethylcyclotetrasiloxane (V-D4) was used instead of 4.62 mmol l,3,5-trivinyl-l,3,5-trimethylcyclo-trisiloxane.

[0161] Sample N - V-D5 (0,20 equivalents): This comparative Example was prepared as Sample M, but 2.8 mmol l,3,5,7,9-pentavinyl-l,3,5,7,9-pentamethylcyclopentasiloxane (V-D5) was used instead of 4.62 mmol l,3,5-trivinyl-l,3,5-trimethylcyclo-trisiloxane (V-D3).

[0162] Sample O - Ep-D4 (0,25 equivalents): This comparative Example was prepared as Sample M, but 3.5 mmol tetrakis [(epoxy cyclohexy l)ethyl]tetramethy Icy clotetrasiloxane (Ep-D4) was used instead of 4.62 mmol l,3,5-trivinyl-l,3,5-trimethylcyclo-trisiloxane (V-D3).

[0163] Sample I - D4 (1 equivalent): This comparative Example was prepared as Sample M, but 1.18 mmol DTHFP, 9,05 mmol BuLi, 9,05 mmol octamethylcyclotetrasiloxane (D4) and 9.05 mmol 2,2- dimethyl-l-oxa-4-thia-2-sila-cyclohexan-6-on were used instead of 1.82 mmol DTHFP, 14 mmol BuLi, 4,62 mmol l,3,5-trivinyl-l,3,5-trimethylcyclo-trisiloxane (V-D3) and 14 mmol 2,2-dimethyl-l-oxa-4- thia-2-sila-cyclohexan-6-on, respectively.

[0164] It was observed that coupling of living S-SBRs with V-D3 leads to significantly lower degrees of coupling, whereas no significant difference could be observed between V-D4 and V-D5. The shape of the molecular weight distribution was similar for all three tested coupling agents, while the shapes for V-D4 and V-D5 resembled more closely. A lower degree of coupling was obtained with Ep-D4 compared to V-D4.

[0165] The following A5 values were determined:

[0166] Further data are compiled in the table here below:

[0167] Methods

[0168] The number-average molecular weight Mn, the weight average molecular weight Mw, the dispersity £> = Mw / Mn were determined using gel permeation chromatography (GPC) at 35 °C (THF as solvent and polystyrene calibration).

[0169] The microstructure (vinyl and styrene content) were determined according to ISO 12965:2000

[0170] DSC analysis was carried out in accordance with ISO 11357-1 20165 (D) with a DSC 300 Caliris (QS no. 04119) from Netzsch. For the measurement, 40 pL aluminum crucibles were used, which were tightly sealed by a cold welding process. Nitrogen with a purity of >99% was used as the purge gas. The device was function-tested using three substances (indium, cyclohexane and n-heptane). The onset of the melting temperature was recorded for each substance. For indium the melting enthalpy was also included in the functional test. DSC measurements were performed from -150 °C to 100 °C with a heating rate of 20 K / min.

[0171] A5 (Delta delta) values were determined by measuring the phase angle 5 by means of a rubber process analyzer (RPA) at 100 °C in a frequency sweep from 0.01 Hz to 40 Hz and a deflection angle of 0.5° (shear amplitude of 6.98%), wherein A5 is the 5 value at 0.1 rad / sec minus the 5 value at 100 rad / s.

[0172] The Mooney viscosity (MV) was measured according to DIN ISO 289-1 (2018) at the measuring conditions ML(l+4) at 100 °C. Mooney Stress Relaxation (MSR) was determined from the same measurement according to ASTM D 1646-00.

[0173] Dynamic properties of vulcanized compounds were determined according to DIN53513-1990 on Eplexor 500 N from Gabo-Testanlagen GmbH, Ahlden, Germany at 10 Hz in the temperature range from -100° C to +100° C at a heating rate of 1 K / min (Sample: strips with l*w*t= 60mm*10mm*2mm; free length between sample holder 30mm). The following properties can be determined this way: tan delta (60° C), i.e. the loss factor (E" / E') at 60 °C; and tan 5 (0 °C), i.e. the loss factor (E" / E') at 0° C. tan delta (60° C) is a measure of hysteresis loss from the tire under operating conditions. As tan delta (60 °C) decreases, the rolling resistance of the tire decreases, tan delta (0° C) is a measure for the wet grip of the material. As tan 5 (0° C) increases the wet grip increases.

[0174] Elastic properties were determined according to DIN53513-1990. An elastomer test system (MTS Systems GmbH, 831 Elastomer Test System) was used. The measurements were carried out at 60 °C in double shear mode with no static pre-strain in shear direction and oscillation around 0 on cylindrical samples (2 samples each 20^6 mm, pre-compressed to 5 mm thickness) and a measurement frequency of 10 Hz in the strain range from 0.1 to 40%. The method was used to obtain the following properties:

[0175] G’ (0.5%): dynamic modulus at 0.5% amplitude sweep, G’ (15%): dynamic modulus at 15% amplitude sweep, G’ (0.5%) - G’ (15%): difference of dynamic modulus at 0.5% relative to 15% amplitude sweep (also referred to as Payne effect), tan delta 7 %: loss factor (G" / G') at 7 % deformation.

[0176] The difference of G’ (0.5%) - G’ (15%) is an indication of the Payne effect of the mixture. The lower the value the better the distribution of the fdler in the mixture, the better the rubber-filler interaction. Tan delta 7 % is another measure of the hysteresis loss from the tire under operating conditions. As tan 5 7 % decreases, the rolling resistance of the tire decreases.

[0177] The rebound elasticity was determined at 60 °C according to DIN 53512.Example 2 - silica-fdled tire tread compound study:

[0178] In a silica-fdled tire tread compound study, the poly diene rubbers of Samples M, K, N, O, and I as well as two references were tested.

[0179] The silica tread compound recipes with 100 phr S-SBR are compiled in the table here below:

[0180] Ref. A is an TDAE oil-extended (5phr) S-SBR sample functionalized according to WO2014 / 173706A1 (32 wt.-% vinyl, 11 wt.-% styrene, ML(l+4)@100°C = 62 MU, A5 = 35°. Ref. B was peoduced as described for sample K.

[0181] Rubber compositions were prepared in a 1.5 L kneader using the mixing protocol shown in following table. The resulting compositions were vulcanized at 160 °C.

[0182] Mixing protocol:

[0183] Performance data are compiled in the tables here below:

[0184] As shown by the above test results, Ep-D4 has a significantly worse rolling resistance performance. V-D4 and V-D5 show similar coupling properties and yield polymers with similar compound performance. V-D3 has a lower degree of coupling and showed following benefits in the compound study:- improved filler dispersion (as demonstrated by lower Payne effect; G'(0,5%)-G'(15%));- lower compound Mooney viscosity (MV); and- excellent rolling resistance indicators (as demonstrated by low tan delta 60°C (Epl.), low tan delta 7 % (MTS), high rebound 60°C).

Claims

Patent claims:

1. A branched poly diene rubber comprising- repeating units derived from at least one aliphatic conjugated diene monomer; and- branching units, derived from at least one 6-membered cyclic siloxane; wherein the polydiene rubber has(i) a glass transition temperature (Tg) of at most -37°C, determined according to DIN EN ISO 11357;(ii) a Mooney viscosity ML1+4 at 100°C within the range of from 50 MU to 160 MU; determined according to EN ISO 289; and(iii) a A5 value within the range of from 13° to 32°, determined by measuring the phase angle 5 by means of a rubber process analyzer (RPA) at 100°C in a frequency sweep from 0.01 Hz to 40 Hz and a deflection angle of 0.5° (shear amplitude of 6.98%), wherein A5 is the 5 value at 0.1 rad / sec minus the 5 value at 100 rad / s.

2. The poly diene rubber according to claim 1, wherein the glass transition temperature is within the range of from -90°C to -40°C, preferably -85°C to -45°C, more preferably -80°C to -50°C, still more preferably -75°C to -55°C, and yet more preferably -70°C to -60°C.

3. The poly diene rubber according to claim 1 or 2, wherein the Mooney viscosity ML 1+4 at 100°C is within the range of from 65 MU to 140 MU, preferably 70 MU to 135 MU, more preferably 75 MU to 130 MU, still more preferably 80 MU to 125 MU, and yet more preferably 85 MU to 120 MU.

4. The polydiene rubber according to any of the preceding claims, wherein the A5 value is at least 14°, preferably at least 15°, more preferably at least 16°, still more preferably at least 17°, yet more preferably at least 18°, even more preferably at least 19°, most preferably at least 20°, and in particular at least 21°.

5. The poly diene rubber according to any of the preceding claims, wherein the A5 value is at most 31°, preferably at most 30°, more preferably at most 29°, still more preferably at most 28°, yet more preferably at most 27°, even more preferably at most 26°, most preferably at most 25°, and in particular at most 24°.

6. The polydiene rubber according to any of the preceding claims, wherein the A5 value is within the range of from 19° to 32°; preferably 18° to 32°; more preferably 20° to 32°; still morepreferably 21° to 32°; yet more preferably 22° to 32°; even more preferably 23° to 32°; most preferably 24° to 32°; and in particular 25° to 31°.

7. The polydiene rubber according to any of the preceding claims, which has a number average molecular weight (Mn) of at most 800,000 g / mol, preferably at most 750,000 g / mol, more preferably at most 700,000 g / mol, still more preferably at most 650,000 g / mol, yet more preferably at most 600,000 g / mol, even more preferably at most 550,000 g / mol, most preferably at most 500,000 g / mol, and in particular at most 450,000 g / mol; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

8. The poly diene rubber according to any of the preceding claims, which has a poly dispersity index (PDI) within the range of from 1.20 to 1.80, preferably 1.30 to 1.70, more preferably 1.40 to 1.60; determined by GPC according to DIN EN ISO 13885 with polystyrene standard.

9. The polydiene rubber according to any of the preceding claims, which has a vinyl content within the range of from 26.0 wt.-% to 35.0 wt.-%, preferably 27.0 wt.-% to 34.0 wt.-%, more preferably 28.0 wt.-% to 33.0 wt.-%, still more preferably 29.0 wt.-% to 32.0 wt.-%, and yet more preferably 30.0 wt.-% to 31.0 wt.-%; determined according to ISO 12965:200010. The poly diene rubber according to any of the preceding claims, wherein the at least one aliphatic conjugated diene is a C4-25 aliphatic conjugated diene; preferably 1,3-butadiene.

11. The polydiene rubber according to any of the preceding claims, which comprises repeating units derived from at least one copolymerizable vinylaromatic comonomer; preferably selected from styrene, ortho-methyl styrene, meta-methyl styrene, para-methyl styrene, para-tertbutyl styrene and combinations thereof; preferably styrene.

12. The polydiene rubber according to any of the preceding claims, wherein the at least one 6-mem- bered cyclic siloxane is an aliphatic cyclic siloxane, preferably an aliphatic cyclic alkyl vinyl siloxane, more preferably 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane.

13. A method of making a polydiene rubber according to any of the preceding claims, said method comprising the steps of:(a) polymerizing the at least one aliphatic conjugated diene monomer to produce a polymer having reactive polymer chain ends;(b) reacting at least some of the reactive polymer chain ends with the at least one 6-membered cyclic siloxane; and(c) optionally, introducing at least one functional group to the polydiene rubber by means of a functionalization agent, wherein optional step (c) is carried out before, after or during step (b).

14. A curable composition comprising- the poly diene rubber according to any of claims 1-12 and- at least one vulcanization agent for curing the poly diene rubber; preferably wherein the content of the vulcanization agent is within the range of from 0.5 to 10 parts by weight per 100 parts by weight of diene rubber.

15. A composition comprising a cured poly diene rubber obtained by curing the curable composition of claim 14; preferably wherein the composition is an article, more preferably selected from a tire or a tire tread.

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