Tyre for vehicle wheels

Abstract

The invention relates to a tyre comprising at least one structural element comprising a vulcanized elastomeric material obtained by vulcanizing a vulcanizable elastomeric composite made by mixing an elastomeric composition, the elastomeric composition comprises, per 100 phr of a diene elastomeric polymer: (a) from 30 phr to 95 phr of at least one styrene-butadiene polymer (SBR); (b) from 5 phr to 70 phr of at least one diene elastomeric polymer selected from the group consisting of at least one isoprene polymer (IR), at least one butadiene polymer (BR) or mixtures thereof; (c) from 10 phr to about 120 phr, preferably from 20 phr to 100 phr, of at least one white reinforcing filler; (d) from about 1% to about 20% by weight of at least one silane coupling agent relative to the amount of the white reinforcing filler; (e) from 1% to 35% by weight, preferably from 5% to 25%, with respect to the amount of silane coupling agent.

Description

Technical Field

[0001] The present invention relates to a tire for vehicle wheels, comprising a vulcanized elastomeric material obtained by vulcanizing a vulcanizable elastomeric compound, the vulcanizable elastomeric compound being prepared by mixing an elastomeric composition comprising at least one diene elastomeric polymer, silica as reinforcing filler, and at least one silane coupling agent, characterized in that the incorporation of a polyamine makes it possible to improve the vulcanization kinetics and the tire properties, in particular to improve the balance between rolling resistance, wear resistance and mechanical properties. Background Art

[0002] In the tire industry, vulcanization is a process commonly used to impart the necessary mechanical properties to the elastomeric compositions of tire components. This treatment affects the static and dynamic moduli as well as the hysteresis of the elastomeric composition at different temperatures, thus affecting the behavior of the tire on dry or wet surfaces and the rolling resistance and the tear and wear resistance of the tire during use.

[0003] Vulcanization generally uses sulfur to promote crosslinking of the elastomeric composition and reinforcement with, for example, carbon black to improve the mechanical characteristics of the finished product.

[0004] However, the use of large amounts of sulfur causes significant reversion, which results in changes in tire performance during use, while the use of large amounts of carbon black produces significant hysteresis, i.e., increased heat dissipation under dynamic conditions, which results in increased tire rolling resistance and increased fuel consumption.

[0005] In order to overcome the disadvantages caused by the use of carbon black, so-called white reinforcing fillers can be used, in particular silica as a complete or partial replacement for carbon black.

[0006] However, while the use of said white reinforcing fillers results in lower hysteresis and subsequently lower rolling resistance, it also implies a reduction in mechanical properties, in particular a reduction in tear resistance, mainly due to the poor affinity of these white reinforcing fillers compared to the elastomeric polymers commonly used in tire production.

[0007] In particular, in order to achieve a good dispersion of silica in the elastomeric polymer, it is necessary to subject the elastomeric composition to a prolonged thermomechanical mixing action ("siliconization" process), while in order to increase the affinity of silica for the elastomeric polymer, it is necessary to use suitable coupling agents, such as sulfur-containing organosilane products ("silanization" treatment).

[0008] However, the need to use such coupling agents places limits on the maximum temperatures that can be reached during the mixing and thermomechanical treatment operations of the elastomeric composition in order to avoid irreversible thermal degradation of the coupling agent.

[0009] In order to overcome the above-mentioned disadvantages, the prior art has suggested introducing other compounds that can promote the reaction of silica with coupling agents, thereby improving the interaction with elastomeric polymers, such as described in WO2021 / 014394, EP2193036 and EP2231759 in the name of the present applicant.

[0010] Although the solutions proposed in the art have brought improvements, the tire industry continues to be interested in finding new solutions suitable for obtaining optimal performance in terms of mechanical properties and hysteresis while maintaining good stability, processability and vulcanization kinetics of the elastomeric composition. Summary of the invention

[0011] The Applicant has carried out research to further improve the effectiveness of coupling agents in the production of tyre compounds, with the aim of obtaining a better balance of the vulcanization curve by obtaining good hysteresis values, without affecting the mechanical properties of the vulcanizate (ie the vulcanized elastomeric material).

[0012] Surprisingly, the Applicant has discovered that, by using polyamines in an elastomeric composition comprising at least one diene elastomeric polymer, silica as reinforcing filler and at least one silane coupling agent, it is possible to adjust the final properties of the vulcanized elastomeric material according to the desired properties.

[0013] In particular, the Applicant has observed that the presence of polyamines makes it possible to improve both the static mechanical properties (in particular the modulus of elongation and the tear resistance) and the dynamic mechanical properties, as well as to significantly reduce the hysteresis and the rolling resistance, in particular by reducing the tan δ values ​​at high temperatures, while maintaining sufficient tan δ values ​​at low temperatures, thus maintaining good grip even on wet surfaces and at low temperatures.

[0014] At the same time, the Applicant has observed higher values ​​of the silanization yield, which allows reducing the amount of coupling agent used and thus obtaining a more stable system, especially when the coupling agent is a thiosilane, since the thiosilane can act as a sulfur donor and initiate the vulcanization.

[0015] Furthermore, the Applicant has demonstrated that the vulcanization curve is significantly influenced by the presence of polyamines.

[0016] In particular, the Applicant has observed that by increasing the percentage of polyamine, the vulcanization curve changes from a typical shape with an increasing modulus to a shape including a modulus value reaching a constant maximum, without ever observing a reversion phenomenon. In addition, the vulcanization kinetics are faster, allowing shorter vulcanization cycles in industrial production processes.

[0017] Finally, the Applicant has observed that the viscosity and the scorch values ​​remain within acceptable values, allowing to maintain a good processability of the elastomeric composition.

[0018] A first aspect of the invention is therefore to provide a tire comprising at least one structural element comprising a vulcanized elastomeric material obtained by vulcanizing a vulcanizable elastomeric compound made by mixing an elastomeric composition comprising, per 100 phr of a diene elastomeric polymer:

[0019] (a) 30 to 95 phr of at least one styrene-butadiene polymer (SBR);

[0020] (b) 5 to 70 phr of at least one diene elastomeric polymer chosen from the group consisting of at least one isoprene polymer (IR), at least one butadiene polymer (BR) or mixtures thereof;

[0021] (c) 10 to about 120 phr, preferably 20 to 100 phr, of at least one white reinforcing filler;

[0022] (d) from about 1% to about 20% by weight of at least one silane coupling agent relative to the amount of the white reinforcing filler;

[0023] (e) 1 to 35%, preferably 5 to 25% by weight of a polyamine relative to the amount of the silane coupling agent.

[0024] According to a preferred embodiment, the tire of the present invention comprises:

[0025] - a carcass structure having opposite side edges associated with respective left and right bead structures;

[0026] - a tread band applied in a radially outer position with respect to said carcass structure;

[0027] - A pair of side walls applied laterally on opposite sides of said carcass structure.

[0028] In a second aspect of the invention, the invention relates to an elastomeric composition comprising, per 100 phr of diene elastomeric polymer:

[0029] (a) 30 to 95 phr of at least one styrene-butadiene polymer (SBR);

[0030] (b) 5 to 70 phr of at least one diene elastomeric polymer chosen from the group consisting of at least one isoprene polymer (IR), at least one butadiene polymer (BR) or mixtures thereof;

[0031] (c) 10 to about 120 phr, preferably 20 to 100 phr, of at least one white reinforcing filler;

[0032] (d) from about 1% to about 20% by weight of at least one silane coupling agent relative to the amount of the white reinforcing filler;

[0033] (e) 1 to 35%, preferably 5 to 25% by weight of a polyamine relative to the amount of the silane coupling agent.

[0034] definition

[0035] The term "elastomeric composition" refers to a composition comprising at least one elastomeric polymer and one or more additives, which, by mixing and possibly heating, provides an elastomeric compound suitable for use in tires and parts thereof. The elastomeric composition is "vulcanizable" because it contains a vulcanizing agent.

[0036] The components of the elastomeric composition are not usually introduced into the mixer simultaneously, but are typically added sequentially. In particular, vulcanization additives, such as vulcanizing agents and possible accelerators and retarders, are usually added in a step downstream with respect to the incorporation and processing of all other components.

[0037] In the final vulcanizable elastomeric compound, the individual components of the elastomeric composition may be altered or no longer individually traceable because they are fully or partially modified by interaction with other components as a result of thermal and / or mechanical treatments. The term "elastomeric composition" herein is meant to include the collection of all components used to prepare the elastomeric compound, whether they are actually present simultaneously, introduced sequentially or subsequently traceable in the elastomeric compound or the final tire.

[0038] The term "elastomeric polymer" means a natural or synthetic polymer which, after vulcanization, can be repeatedly stretched at room temperature to at least twice its original length and, after the tensile load is removed, recovers essentially immediately under the action of the force to approximately its original length (as defined in ASTM D1566-11 Standard Terminology Relating to Rubber).

[0039] The term "diene polymer" means a polymer or copolymer derived from the polymerization of one or more different monomers, at least one of which is a conjugated diene (conjugated diene). These polymers may be partially or fully hydrogenated.

[0040] The term "elastomeric compound" means a compound obtained by mixing and possibly heating an elastomeric composition comprising at least one elastomeric polymer and at least one of the additives usually used in the preparation of tyre compounds.

[0041] The term "vulcanizable elastomeric compound" denotes an elastomeric compound ready for vulcanization obtainable by incorporating into the elastomeric compound all additives, including those that are vulcanizable.

[0042] The term "vulcanized elastomeric compound" refers to a material obtained by vulcanizing a vulcanizable elastomeric compound.

[0043] The term "green" refers to a material, compound, composition, component or tire that has not yet been cured.

[0044] The term "vulcanization" refers to the cross-linking reaction in natural or synthetic rubber caused by typical sulfur-based cross-linking agents.

[0045] The term "vulcanizing agent" means a product capable of converting natural or synthetic rubber into an elastic and resistant material due to the formation of a three-dimensional network of intermolecular and intramolecular bonds. Typical vulcanizing agents are sulfur-based compounds such as elemental sulfur, polymeric sulfur, sulfur donors such as bis[(trialkoxysilyl)propyl]polysulfide, thiuram, dimorpholine dithioate and caprolactam-disulfide.

[0046] The term "vulcanization accelerator" refers to compounds capable of shortening the duration of the vulcanization process and / or lowering the operating temperature, for example sulfonamides, thiazoles, dithiophosphoric acids, dithiocarbamates, guanidines and sulfur donors such as thiuram.

[0047] The term "vulcanization activator" refers to a product that is able to further accelerate vulcanization, so that vulcanization occurs in a shorter time and possibly at a lower temperature. An example of an activator is the stearic acid-zinc oxide system.

[0048] The term "vulcanization retarder" refers to a product capable of delaying the onset of the vulcanization reaction and / or inhibiting undesirable side reactions, such as N-(cyclohexylthio)phthalimide (CTP).

[0049] The term "vulcanization package" refers to a vulcanizing agent and one or more vulcanization additives selected from the group consisting of vulcanization activators, accelerators and retarders.

[0050] The term "reinforcing filler" refers to reinforcing materials typically used in the art to improve the mechanical properties of tire rubber, preferably selected from carbon black, conventional silica (for example silica in sand precipitated with strong acid, preferably amorphous silica), diatomaceous earth, calcium carbonate, titanium dioxide, talc, aluminum oxide, aluminosilicates, kaolin, silicate fibers and mixtures thereof.

[0051] The term "white filler" refers to conventional reinforcing materials used in this field, selected from conventional silicas and silicates, such as sepiolite, palygorskite (also known as attapulgite), montmorillonite, alloisite and the like, which may be modified by acid treatment and / or derivatization. Typically, white fillers have surface hydroxyl groups.

[0052] The term "mixing step (1)" denotes the step of the process for the preparation of an elastomeric compound in which, by mixing and possibly heating, one or more additives other than the vulcanizing agent fed in step (2) may be incorporated. The mixing step (1) is also called a "non-productive step". In the preparation of a compound, there may be several "non-productive" mixing steps which may be denoted 1a, 1b, etc.

[0053] The term "mixing step (2)" denotes the next step of the preparation process of the elastomeric compound, in which the vulcanizing agent and possibly other additives in a vulcanization package are introduced into the elastomeric compound obtained from step (1) and mixed in the material at a controlled temperature (generally at a compound temperature below 120°C) so as to provide a vulcanizable elastomeric compound. The mixing step (2) is also called a "productive step".

[0054] For purposes of this description and the claims that follow, the term "phr" (acronym for parts per hundred parts of rubber) means the parts by weight of a given elastomeric compound component per 100 parts by weight of elastomeric polymer, disregarding any extending oil.

[0055] Unless otherwise indicated, all percentages are expressed as weight percent. DETAILED DESCRIPTION

[0056] The present invention, in at least one of the aforementioned aspects, may exhibit one or more of the following preferred features.

[0057] The elastomeric composition used for manufacturing at least one structural element of the tire of the invention comprises, per 100 phr of diene elastomeric polymer: from 30 to 95 phr of at least one styrene-butadiene polymer (SBR); and from 5 to 70 phr of at least one elastomeric polymer, wherein said elastomeric polymer is chosen from the group consisting of at least one isoprene polymer (IR), at least one butadiene polymer (BR) or mixtures thereof.

[0058] According to one embodiment, the elastomeric composition used to manufacture at least one structural element of the tire of the invention is an elastomeric compound comprising, per 100 phr of diene elastomeric polymer:

[0059] (a) 40 to 70 phr, preferably 45 to 65 phr, of at least one styrene-butadiene polymer (SBR);

[0060] (b) 10 to 40 phr, preferably 15 to 35 phr of at least one isoprene polymer (IR); and

[0061] (c) 20 to 50 phr, preferably 25 to 45 phr, of at least one butadiene polymer (BR).

[0062] According to another embodiment, the elastomeric composition used to manufacture at least one structural element of the tire of the invention is an elastomeric compound comprising, per 100 phr of diene elastomeric polymer:

[0063] (a) 50 to 80 phr, preferably 55 to 75 phr, of at least one styrene-butadiene polymer (SBR); and

[0064] (b) 20 to 50 phr, preferably 25 to 45 phr, of at least one butadiene polymer (BR).

[0065] According to other embodiments, the elastomeric composition used to manufacture at least one structural element of the tire of the invention is an elastomeric compound comprising, per 100 phr of diene elastomeric polymer:

[0066] (a) 50 to 80 phr, preferably 55 to 75 phr, of at least one styrene-butadiene polymer (SBR); and

[0067] (b) 20 to 50 phr, preferably 25 to 45 phr of at least one isoprene polymer (IR).

[0068] Herein, styrene-butadiene (SBR) polymer refers to a copolymer comprising monomer units of styrene and butadiene, wherein the weight percentage of styrene is preferably in the range of 10% to 55%, more preferably in the range of 20% to 45%, and the weight percentage of vinyl (relative to butadiene) is preferably in the range of 10% to 70%, more preferably in the range of 15% to 65%.

[0069] Styrene-butadiene polymers may contain, in addition to styrene units and butadiene units, small amounts (e.g., 5% or less by weight) of other monomer units such as isoprene, dimethylbutadiene, pentadiene, methylstyrene, ethylstyrene, divinylbenzene, and diisopropenylbenzene.

[0070] Advantageously, the elastomeric composition according to the invention comprises from 40 to 80 phr of at least one styrene-butadiene (SBR) polymer.

[0071] Preferably, the styrene-butadiene polymer is a random polymer.

[0072] Preferably, the styrene-butadiene polymer may have a weight average molecular weight between 100,000 and 2,000,000 g / mol, preferably between 150,000 and 1,000,000, more preferably between 200,000 and 600,000 g / mol.

[0073] Styrene-butadiene polymers can be prepared according to known techniques such as described in US2019062535, US2019062529 or US4547560.

[0074] In one embodiment, the styrene-butadiene polymer is prepared by solution polymerization (S-SBR).

[0075] In general, solution synthesis provides polymers with narrower molecular weight distribution, less chain branching, larger molecular weight, and higher cis-1,4-polybutadiene content than polymers obtainable in emulsion.

[0076] In another embodiment, the styrene-butadiene polymer is prepared by emulsion polymerization (E-SBR).

[0077] The styrene-butadiene polymer may be a functionalized polymer, such as the functionalized SBR described in US2019062535 (paragraphs 9-13), US2019062529 (paragraphs 19-22), WO2017 / 211876A1 (component a), or WO2015 / 086039A1.

[0078] Functional groups can be introduced into the styrene-butadiene polymer by treatments known in the art, such as during the production of the styrene-butadiene polymer, by copolymerization with at least one corresponding functionalized monomer containing at least one ethylenic unsaturation, or by subsequent modification of the styrene-butadiene polymer by grafting at least one functionalized monomer in the presence of a free radical initiator (e.g., an organic peroxide).

[0079] Alternatively, functionalization can also be introduced by reaction with a suitable terminator or coupling agent. In particular, styrene-butadiene polymers obtained by anionic polymerization in the presence of an organometallic initiator (particularly an organolithium initiator) can be functionalized by reacting the residual organometallic groups derived from the initiator with a suitable terminator or coupling agent (such as, for example, amines, amides, imines, carbodiimides, alkyltin halides, substituted benzophenones, alkoxysilanes, aryloxysilanes, alkylthiols, alkyldimercaptosilanes, carboxyalkylthiols, carboxyalkylthiolsilanes and thioglycols).

[0080] Useful examples of terminators or coupling agents are known in the art and are described in, for example, patents EP2408626, EP2271682, EP3049447A1, EP2283046A1, EP2895515A1, WO2015 / 086039A1 and WO2017 / 211876A1.

[0081] Commercial examples of SBR polymers useful in the present invention are Tufdene E581 and E680 polymers from Asahi-Kasei (Japan), SPRINTAN SLR4602, SLR3402, SLR4630 and 941S from Trinseo (Germany), BUNA SL-4518 and BUNA SE 1502 from Arlanxeo (Germany), Europrene 5543T, Europrene 1739 and Intol 1789 from Eni (Italy), HPR620 and HP 755 from Japan Synthetic Rubber Co. (Japan), and NIPOL NS 522 from Zeon Co. (Japan).

[0082] In this context, isoprene polymer or isoprene rubber (IR) refers to a synthetic or natural elastomer obtained by 1,4-cis addition of isoprene. Preferably, the isoprene polymer is natural rubber (NR). Isoprene polymers and natural rubber are well known to those skilled in the art of tires. The isoprene polymer can optionally be functionalized with the same terminators or coupling agents as described above.

[0083] Advantageously, the elastomeric composition according to the invention comprises from 10 to 50 phr of at least one isoprene polymer (IR).

[0084] Commercial examples of suitable isoprene polymers are SIR20 from Aneka Bumi Pratama or STR 20 from Thaiteck Rubber.

[0085] Polybutadiene polymers (BR) are synthetic rubbers obtained by polymerization of 1,3-butadiene, preferably by nickel or neodymium catalysis.

[0086] The polybutadiene polymer preferably comprises a polybutadiene rubber having a cis group content greater than 90%, more preferably greater than 95%. The cis content of the polybutadiene rubber is usually provided by the supplier and can be determined by the FTIR method. This method is based on the calculation of the intensity of the band attributable to the 1,4-trans and 1,2-vinyl isomers with the band located at 1312 cm -1 The ratio between the reference bands (internal standard) of 1,4-cis and 1,4-cis-1 is determined by the difference with 100. The preparation of the samples is carried out on polybutadiene films obtained starting from solution and evaporated on a KBr window.

[0087] Advantageously, the elastomeric composition according to the invention comprises from 20 phr to 50 phr of at least one butadiene polymer (BR).

[0088] Commercial examples of polybutadiene rubber include ND-PBR (SKDN) produced by PJSC Nizhnekamskneftekhim (Russia), Europrene NEOCIS BR 60 produced by ENI (Italy), and PTFE produced by Arlanxeo (Germany). CB 22 and Nd BR 40 produced by KUMHO (South Korea).

[0089] According to one embodiment, the diene elastomeric polymers used in the elastomeric composition of the invention, in particular styrene-butadiene polymers (SBR), isoprene polymers (IR) and butadiene polymers (BR), may be partially or completely hydrogenated. According to a first variant, a portion of the diene units of the diene elastomeric polymer are hydrogenated. According to a second variant, all the diene units of the diene elastomeric polymer are hydrogenated. The partial or total hydrogenation treatment reduces the double bonds of the diene elastomeric polymer partially or completely to single bonds. The reduction of the double bonds may also be carried out with a treatment other than hydrogenation, for example a reduction treatment with aluminum hydride or a reduction treatment with an imide.

[0090] The white reinforcing filler is preferably selected from conventional silica and silicates in the form of fibers, flakes or particles, such as bentonite, nontronite, beidellite, chrome bentonite, hectorite, saponite, sauconite, vermiculite, sericite, sepiolite, palygorskite (also known as attapulgite), montmorillonite, alloisite, etc., which may be modified and / or derivatized by acid treatment, and mixtures thereof, more preferably silica. Examples of silica are pyrogenic silica, precipitated amorphous silica, wet silica (hydrated silicic acid) or mixtures thereof.

[0091] Preferably, the specific surface area (BET) of the white reinforcing filler is at least 30 m 2 / g, more preferably at least 50m 2 / g, even more preferably at least 80m 2 / g.

[0092] Preferably, the non-functionalized white reinforcing filler has a specific surface area (BET) of less than 400 m 2 / g, more preferably less than or equal to 250m 2 / g, and even more preferably less than or equal to 220m 2 / g.

[0093] Advantageously, the specific surface area (BET) of the white reinforcing filler is about 50 m 2 / g to about 350m 2 / g, more preferably about 70m 2 / g to about 240m 2 / g, even more preferably about 90m 2 / g to about 190m 2 / g.

[0094] An example of a suitable commercial silica is available from PPG Industries (Pittsburgh, Pa.) under the brand name The brand name of Evonik is The product or brand name of Solvay is Products such as precipitated silica Rhodia Zeosil MP1165 (BET surface area 160 m 2 / g), Ultrasil VN3 GR (BET specific surface area 180m 2 / g) and Zeosil 1115MP (BET surface area 95-120m 2 / g).

[0095] For some applications, the elastomeric composition may include, in addition to the white reinforcing filler, at least 1 phr, more preferably at least 2 phr, more preferably at least 3 phr or 4 phr of carbon black.

[0096] The carbon black may be selected from standard tire grade, i.e., having a carbon black content of not less than 20 m 2 / g, more preferably greater than 50m 2 / g surface area (measured according to ASTM D6556-16 standard).

[0097] Commercial examples of carbon black are N375 or N234 marketed by Birla Group (India) or Cabot Corporation.

[0098] Optionally, the elastomeric composition may comprise in admixture one or more reinforcing fillers as defined above.

[0099] Advantageously, the elastomeric composition comprises at least one silane coupling agent capable of interacting with the white reinforcing filler and binding it to the elastomeric polymer during vulcanization.

[0100] The silane coupling agents preferably used are those which can be represented by the following structural formula (I):

[0101] (R2)3Si-C t H 2t -X(I)

[0102] wherein the R2 groups may be the same or different from each other and are selected from: alkyl, alkoxy or aryloxy or halogen atoms, provided that at least one of the R2 groups is an alkoxy group or an aryloxy group; t is an integer between 1 and 6 and inclusive; X is selected from nitroso, mercapto, amino, epoxy, vinyl, imide, chlorine, -(S) u C t H 2t -Si-(R2)3 and -S-COR2, wherein u and t are integers between 1 and 6, and the group R2 is as defined above.

[0103] Particularly preferred silane coupling agents are aminosilanes and thiosilanes.

[0104] According to one embodiment, the silane coupling agent is an aminosilane represented by the following structural formula (II):

[0105] (R)3Si-C n H 2n -[XC m H 2m ] p -Y(II)

[0106] wherein the R groups are the same or different from each other and are selected from alkyl or alkoxy groups having 1 to 4 carbon atoms, provided that at least one of the R groups is an alkoxy group;

[0107] n and m are the same as or different from each other and are an integer from 1 to 6 inclusive;

[0108] p is an integer from 0 to 5, inclusive;

[0109] X is a -NH- group, and

[0110] Y is a -NH2 or NHR' group, wherein R' is an alkyl or cycloalkyl group containing 1 to 6 carbon atoms.

[0111] The aminosilane represented by the structural formula (II) that can be used in the present invention is 2-aminoethyltrimethoxysilane, 2-aminoethyltriethoxysilane, 2-aminoethyltripropoxysilane, 2-aminoethyltributoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane (APTES), 3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyltris(methoxyethoxyethoxy)silane, 3-aminopropyl-diisopropylethoxysilane , 3-(2-aminomethylamino)propyl-triethoxysilane, 3-(2-(2-aminoethylamino)ethylamino)propyltrimethoxysilane, 4-aminobutyltriethoxysilane, 4-aminobutyldimethylmethoxysilane, 4-aminobutyltriethoxysilane, N-(2-aminoethyl)aminomethyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (also known as N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDTMS)), N-(2-aminoethyl)-3-aminopropyl-triethyl Oxysilane, N-(2-aminoethyl)-3-aminopropyl-tri(2-ethylethoxy)silane, N-(2-aminoethyl)-3-aminopropyl-methyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyl-methyldiethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, N-(6-aminohexyl)-3-aminopropyltrimethoxysilane, N-(6-aminohexyl)-3-aminopropyltriethoxysilane, N-2-(vinylbenzylamino)-ethyl-3-aminopropyltrimethoxy Silane, N-cyclohexyl(aminomethyl)methyldiethoxysilane, N-cyclohexyl(aminomethyl)triethoxysilane, N-cyclohexyl(aminomethyl)trimethoxysilane, N-cyclohexyl-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropyltriethoxysilane, N-(n-butyl)-aminomethyltriethoxysilane, N,N-diethylaminopropyltrimethoxysilane, N,N-dimethylaminopropyltrimethoxysilane, N,N-diethylaminomethyltriethoxysilane.

[0112] According to one embodiment, the silane coupling agent is a sulfidosilane represented by the following structural formula (III):

[0113] (R)3Si-C n H 2n -X(III)

[0114] in

[0115] X is thiol (-SH) or -(S) m C n H 2n-Si-(R)3,

[0116] The R groups are the same as or different from each other and are selected from alkyl or alkoxy groups having 1 to 4 carbon atoms, provided that at least one of the R groups is an alkoxy group; and

[0117] n and m are the same as or different from each other and are an integer of 1 to 6 inclusive.

[0118] The sulfosilanes represented by the structural formula (III) that can be used in the present invention are bis[3-(trimethoxysilyl)propyl]-tetrasulfide (TESPT), bis[3-(triethoxysilyl)propyl]-disulfide (TESPD), bis[2-(trimethoxysilyl)ethyl]-tetrasulfide, bis[2-(triethoxysilyl)ethyl]-trisulfide, bis[3-(trimethoxysilyl)propyl]-disulfide, (1-mercaptomethyl)triethoxysilane, (2-mercaptoethyl)triethoxysilane, (3-mercaptopropyl)triethoxysilane, (3-mercaptopropyl)methyldiethoxysilane, (3-mercaptopropyl)methyldimethoxysilane, (3-mercaptopropyl)trimethoxysilane, 3-octanoylthio-1-propyltriethoxysilane and (2-mercaptoethyl)tripropoxysilane.

[0119] Preferred complexes represented by structural formulas (II) and (III) are (i) aminosilanes selected from the group consisting of (3-aminopropyl)triethoxysilane (APTES), (3-aminopropyl)trimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane [also known as N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDTMS)] and N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and (ii) sulfonylsilanes selected from the group consisting of bis[3-(trimethoxysilyl)propyl]-tetrasulfide (TESPT), bis[3-(triethoxysilyl)propyl]-disulfide (TESPD) and (3-mercaptopropyl)trimethoxysilane.

[0120] Preferably, the silane coupling agent is added to the elastomer composition in an amount of 5 to 15% by weight based on the weight of the white reinforcing filler, and more preferably, the silane coupling agent is added to the elastomer composition in an amount of 6 to 10%.

[0121] Advantageously, the elastomeric composition comprises a polyamine capable of interacting with the white reinforcing filler and the silane coupling agent and promoting their distribution in the elastomeric composition and the silanization process.

[0122] The amount of the polyamine in the elastomer composition ranges from 1 to 35% by weight, preferably from 5 to 25% by weight, relative to the amount of the silane coupling agent.

[0123] The polyamines used for the purpose of the present invention consist of linear or branched aliphatic organic complexes comprising at least three amino groups, wherein the amino groups may be primary (—NH 2 ), secondary (—NH—) or tertiary (═N—) amino groups.

[0124] According to one embodiment, the polyamine used for the purpose of the present invention is represented by the following structural formula (IV):

[0125]

[0126] wherein x is an integer of 2 to 6, R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Alk is a divalent straight-chain alkylene group having 1 to 8 carbon atoms.

[0127] In one embodiment, polyamines useful for the purposes of the present invention are, for example, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, heptaethyleneoctamine, dipropylenetriamine, tripropylenetetramine, tetrapropylenepentamine, dibutylenetriamine, tributylenetetramine, tetrabutylenepentamine, dimethylenetriamine, trimethylenetetramine, tetramethylenepentamine, pentamethylenehexamine, di(heptamethylene)triamine, di(trimethylene)triamine, decaethylenedecamine, decamethylenedecamine, N,N-dimethyldiethylenetriamine, N,N-dimethyltetraethylenepentamine, N,N-diethyltetraethylenepentamine, N,N′,N″-trimethyldiethylenetriamine, dipentenetriamine, trienetetramine, tetraheptenepentamine, trioctenenetetramine and tetrapentenepentamine.

[0128] Particularly preferred polyamines are tetramines, such as trimethylenetetramine, triethylenetetramine and tripropylenetetramine. Advantageously preferred is triethylenetetramine.

[0129] The above-mentioned elastomeric composition can be vulcanized according to known techniques, in particular using sulfur-based vulcanization systems commonly used for the manufacture of vulcanizable elastomeric compounds. To this end, a sulfur-based vulcanizing agent is added to the elastomeric composition together with a vulcanization accelerator after one or more thermomechanical treatment steps. In the last treatment step, the temperature is generally kept below 120° C. and preferably below 100° C., in order to avoid any undesirable pre-crosslinking phenomena.

[0130] The vulcanizing agent is preferably selected from sulfur, or alternatively sulfur-containing molecules (sulfur donors), such as caprolactam disulfide (CLD), bis(trialkoxysilyl)propyl]polysulfide, dithiophosphates, phosphoryl polysulfide (SDT) and mixtures thereof.

[0131] Preferably, the vulcanizing agent is sulfur, preferably selected from soluble sulfur (crystalline sulfur), insoluble sulfur (polymeric sulfur), (iii) oil-dispersible sulfur and mixtures thereof.

[0132] Commercial examples of suitable vulcanizing agents are 65% sulfur with the trade name Rhenogran from Lanxess, 67% sulfur with the trade name Crystex OT33 from Eastman, 95% sulfur with the trade name Solvay Schwefel KC, rhombic crystalline sulfur (1% oil and 0.3% silica) with the trade name Sulphur from Zolfindustria.

[0133] The vulcanizing agents are generally present in the elastomeric composition in a total amount ranging from 0.1 phr to 15 phr, preferably from 0.5 phr to 10 phr, even more preferably from 1 phr to 7 phr.

[0134] The elastomeric composition may comprise in admixture one or more vulcanizing agents as defined above.

[0135] The vulcanizing agent is preferably used together with auxiliary agents known to those skilled in the art such as vulcanization activators, accelerators and / or retarders.

[0136] Particularly effective activators are zinc complexes, in particular ZnO, ZnCO3, zinc salts of saturated or unsaturated fatty acids containing 8 to 18 carbon atoms (e.g. zinc stearate), which are preferably formed in situ in the elastomeric composition from ZnO and fatty acids, as well as BiO, PbO, Pb3C4, PbC2 or mixtures thereof.

[0137] The vulcanization accelerator is preferably selected from dithiocarbamates, guanidines, thioureas, thiazoles, sulfenamides, sulfenimides, thiurams, amines, xanthates and mixtures thereof.

[0138] Preferably, the accelerator is selected from N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), N-tert-butyl-2-benzothiazole-sulfenamide (TBBS) and mixtures thereof.

[0139] A commercial example of a suitable accelerator is commercially available from Lanxess. N-cyclohexyl-2-benzothiazole-sulfenamide (CBS or CZ).

[0140] The accelerator is generally present in the elastomeric composition in a total amount ranging between 0.05 and 10 phr, preferably between 0.1 and 5 phr.

[0141] The elastomeric composition may comprise in admixture one or more accelerators as defined above.

[0142] The vulcanization retarder may be selected from, for example, urea, phthalic anhydride, N-nitrosodiphenylamine, N-cyclohexylthiophthalimide (CTP or PVI) and mixtures thereof.

[0143] A commercial example of a suitable retarder is N-cyclohexylthiophthalimide VULKALENT G from Lanxess.

[0144] The retardant is generally present in the elastomeric composition in an amount between 0.05 and 2 phr.

[0145] The elastomeric composition may comprise in admixture one or more retarders as defined above.

[0146] The elastomer composition may include other commonly used additives, which are selected according to the specific use of the elastomer composition. For example, the following substances may be added to the elastomer composition: antioxidants, anti-aging agents, plasticizers, adhesives, anti-ozonants (especially p-phenylenediamines), waxes, modified resins, fibers (such as paste), or a mixture thereof.

[0147] In the mixture, the antioxidant may be selected from the group optionally comprising phenylenediamine, diphenylamine, dihydroquinoline, phenol, benzimidazole, hydroquinone and derivatives thereof.

[0148] The antioxidant is preferably selected from N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N-(1,3-dimethyl-butyl)-n'-phenyl-p-phenylenediamine (6PPD), N,N'-bis-(1,4-dimethyl-pentyl)-p-phenylenediamine (77PD), N,N'-bis-(1-ethyl-3-methyl-pentyl)-p-phenylenediamine (DOPD), N,N'-bis-(1,4-dimethyl-pentyl)-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine (DPPD), D), N,N'-dimethylphenyl-p-phenylenediamine (DTPD), N,N'-di-β-naphthyl-p-phenylenediamine (DNPD), N,N'-bis(1-methylheptyl)-p-phenylenediamine, N,N'-di-sec-butyl-p-phenylenediamine (44PD), N-phenyl-N-cyclohexyl-p-phenylenediamine, N-phenyl-N'-1-methylheptyl-p-phenylenediamine and the like and mixtures thereof, preferably it is N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6-PPD).

[0149] A commercial example of a suitable antioxidant is 6PPD from Solutia / Eastman.

[0150] The antioxidants are generally present in the elastomeric composition in a total amount of between 0 and 20 phr, preferably between 0.5 and 10 phr.

[0151] The wax may be, for example, a petroleum wax or a mixture of paraffin waxes.

[0152] Commercial examples of suitable waxes are Repsol N-paraffin wax blends and 654 microcrystalline wax.

[0153] The wax is generally present in the elastomeric composition in a total amount of between 0 and 20 phr, preferably between 0.5 and 5 phr.

[0154] To further improve the handling properties, the elastomeric composition can be mixed with at least one plasticizer, which is generally selected from mineral oils, vegetable oils, synthetic oils, low molecular weight polymers and mixtures thereof, such as aromatic oils, naphthenic oils, phthalates, soybean oil and mixtures thereof. The amount of plasticizer generally ranges between 0 and 70 phr, preferably between 5 and 30 phr.

[0155] The vulcanizable elastomeric compound obtained by the elastomeric composition and the addition of the above-mentioned additives according to the present invention can be prepared by mixing the basic elastomeric components and other optional additives together according to the known techniques in the art. The mixing step can be carried out, for example, using a drum-type open mixer or a mixer with tangential rotors. Interpenetrating Rotors Type of internal mixer or Ko-Kneader TM type The mixer can be carried out in a continuous mixer of the twin-screw type rotating in the same direction or in a counter-rotating direction.

[0156] The tire according to the invention may be manufactured according to a process comprising the following steps:

[0157] - Building components of a green tyre on at least one forming drum;

[0158] - Shaping, moulding and vulcanising tyres;

[0159] Wherein, constructing at least one of the green tire components comprises:

[0160] - Manufacturing at least one green tire component comprising the elastomeric composition of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0161] The following description will be made with reference to the accompanying drawings, which are provided for illustration purposes only and are therefore not intended to be limiting, in which:

[0162] - Figure 1 A half-section view showing a tire for a motor vehicle wheel according to a first embodiment of the present invention;

[0163] - Figure 2shows a Cartesian curve associated with the vulcanization curves of the elastomeric compounds REF1 and INV1-INV5 described in Example 1; and

[0164] - Figure 3 shows the Cartesian curves associated with the vulcanization curves of the elastomer compounds REF2 and OT1-OT2 described in Example 2;

[0165] - Figure 4 shows the Cartesian curves associated with the vulcanization curves of the elastomeric compounds REF BR, INV BR and OT BR described in Example 3;

[0166] - Figure 5 The Cartesian curves associated with the vulcanization curves of the elastomeric compounds REF NR, INV NR and OT NR described in Example 4 are shown. DETAILED DESCRIPTION

[0168] This description relates by way of example to tyres for motor vehicle wheels. The Applicant considers that the invention can also be applied to tyres for different vehicles such as motorcycles and bicycles.

[0169] Figure 1 In the equation, “a” represents the axial direction and “x” represents the radial direction. Figure 1 Only a portion of the tire is shown, the remaining portion not shown is identical and arranged symmetrically with respect to the radial direction "x".

[0170] refer to Figure 1 , a tyre 100 for a motor vehicle wheel comprises at least one carcass structure including at least one carcass layer 101 of elastomeric material having opposite end flaps respectively engaged with respective annular anchoring structures 102, called bead cores, which may be coupled to a bead filler 104 of elastomeric material. The tyre region comprising the bead core 102 and the filler 104 forms a reinforcing annular structure 103, the so-called bead, which is intended to anchor the tyre to a corresponding mounting rim (not shown).

[0171] The carcass structure is usually of the radial type, i.e. the reinforcing elements of at least one carcass layer 101 are located in a plane including the axis of rotation of the tire and substantially perpendicular to the equatorial plane of the tire. The reinforcing elements are usually composed of textile cords, such as rayon, nylon, polyester (such as polyethylene naphthalate, PEN). Each reinforcing annular structure is formed by folding back the opposite lateral edges of at least one carcass layer 101 around annular anchoring structures 102 so as to form a Figure 1 The so-called carcass flap 101a shown is coupled to the carcass structure.

[0172] In one embodiment, the coupling between the carcass structure and the reinforcing annular structure may be provided by a second carcass layer ( Figure 1 ) is provided.

[0173] Each reinforcing annular structure 103 is provided with a wear strip 105 of elastomeric material at an outer position. Preferably, each wear strip 105 is arranged at least at an axial outer position of the reinforcing annular structure 103 and extends at least between the side wall 108 and a radially lower portion of the reinforcing annular structure 103.

[0174] Preferably, the wear strips 105 are arranged to surround the reinforcing annular structure 103 along the axially inner and outer sides and the radially lower region thereof so that the wear strips are located between the reinforcing annular structure 103 and the rim when the tyre 100 is mounted on the rim.

[0175] The carcass structure is associated with a belt structure 106 of elastomeric material, comprising one or more belt layers 106a, 106b radially superposed relative to each other and relative to the carcass layer and generally having metallic reinforcing cords. Such reinforcing cords may have a cross orientation relative to the circumferential extension direction of the tire (100). A "circumferential" direction is a direction generally facing the direction of rotation of the tire.

[0176] At least one zero-degree reinforcement layer 106c, often referred to as a "0° belt", may be applied at the radially outermost position of the belt layers 106a, 106b, which typically incorporates a plurality of reinforcing cords (typically textile cords) oriented in a substantially circumferential direction and coated with an elastomeric material, thereby forming an angle of several degrees (e.g., between about 0° and 6°) relative to the equatorial plane of the tire.

[0177] A tread band 109 of elastomeric material is applied in a radially outer position to the belt structure 106 .

[0178] Moreover, respective side walls 108 of elastomeric material are further applied in an axially outer position on the lateral surface of the carcass structure, each extending from one of the lateral edges of the tread 109 at a respective reinforcing annular structure 103 .

[0179] In a radially outer position, the tread band 109 has a rolling surface 109a intended to come into contact with the ground. A circumferential groove is usually formed on this rolling surface 109a, which is formed by transverse notches ( Figure 1 The circumferential grooves are connected to define a plurality of blocks of different shapes and sizes distributed on the rolling surface 109a. For simplicity, the rolling surface is Figure 1 Shown as smooth.

[0180] A bottom layer 111 of elastomeric material is arranged between the belt structure 106 and the tread band 109 .

[0181] Strips of elastomeric material 110, generally called “micro-sidewalls”, may optionally be provided in the connection zone between the sidewalls 108 and the tread band 109, which micro-sidewalls are generally obtained by co-extrusion with the tread band 109 and which allow improving the mechanical interaction between the tread band 109 and the sidewalls 108. Preferably, the end portions of the sidewalls 108 directly cover the lateral edges of the tread band 109.

[0182] For a tubeless tire, a layer of elastomeric material 112 (commonly called “liner”) may also be provided in a radially inner position relative to the carcass layer 101 , which provides the necessary impermeability for inflation of the tire.

[0183] The stiffness of the tire sidewall 108 may be increased by providing the bead structure 103 with a reinforcing layer 120, commonly referred to as a flipper, or an additional strip-like insert. Typically, the flipper 120 comprises a plurality of textile cords incorporated within a layer of elastomeric material.

[0184] The bead cover 120 is a reinforcement layer wound around the corresponding bead core 102 and the bead filler 104 to at least partially surround the bead core and the bead filler, and the reinforcement layer is arranged between at least one carcass layer 101 and the bead structure 103. Generally, the bead cover is in contact with the at least one carcass layer 101 and the bead structure 103.

[0185] The bead structure 103 of the tyre may comprise a further protective layer, generally known by the term “chafer” 121 or protective strip and which has the function of increasing the rigidity and integrity of the bead structure 103 .

[0186] The chafer 121 generally comprises a plurality of cords incorporated in a layer of elastomeric material. Such cords are generally made of textile material (eg aramid or rayon) or metal material (eg steel cord).

[0187] The elastomeric composition according to the invention may advantageously be used for the manufacture of an elastomeric material incorporated in one or more of the components of a tire chosen from the tread band, the tread underlayer, the sidewalls and in general any structural element using silica as reinforcing element, preferably in the tread, even if this tread is made of two radially superimposed layers having a radially outer portion ("crown") and a radially inner portion ("base") containing different amounts of silica (called "crown and base" tread).

[0188] The use of the elastomeric composition for manufacturing the elastomeric material of the above-mentioned components allows obtaining tires with lower rolling resistance and therefore lower heat generation and fuel consumption, while obtaining good tear resistance of the tire surface and good handling during its use.

[0189] The building of the tyre 100 as described above can be carried out by assembling the corresponding semi-finished products on a forming drum (not shown) by means of at least one assembling device.

[0190] At least part of the components intended to form the carcass structure of the tyre may be built and / or assembled on a forming drum. More particularly, the forming drum is intended to receive first a possible liner and then the carcass structure and the wear strips. Subsequently, means not shown coaxially engage one of the annular anchoring structures around each of the end flaps, position the external sleeve comprising the belt structure and the tread band in a coaxially centered position around the cylindrical carcass sleeve and shape the carcass sleeve according to a substantially annular configuration by radial expansion of the carcass structure so that the carcass sleeve bears against the radially inner surface of the external sleeve.

[0191] After the green tyre has been built, it is generally subjected to moulding and vulcanization processes in order to determine the structural stability of the tyre by crosslinking the elastomeric composition, as well as to impart the desired tread pattern to the tread band and any distinctive graphic symbols to the sidewalls.

[0192] According to an embodiment not shown, the tyre may be a tyre for motorcycle wheels, which is generally a tyre having straight sections each characterized by a high tread camber angle.

[0193] According to an embodiment not shown, the tire may be a tire for a bicycle wheel.

[0194] The following is a description of some preliminary examples and comparative examples according to the present invention, which are only used for illustration and not for limiting the protection scope of the present invention.

[0195] Experimental Section

[0196] Analytical methods

[0197] Scorch time The time required for the Mooney viscosity to increase by 5 points is measured in minutes at 127°C according to ISO 289 / 2 (1994).

[0198] According to ISO 289-1:1994, the thermal conductivity of non-vulcanized elastomeric compositions at 100°C is Moni ML (1+ 4) Viscosity .

[0199] According to ISO 48:2007, the vulcanized elastomeric composition is measured at 23°C. IRHD hardness .

[0200] MDR Rheological Analysis (According to ISO 6502): Use an Alpha Technologies model MDR2000 rheometer. The test is carried out at 170°C for 30 minutes, with an oscillation frequency of 1.66 Hz (100 oscillations per minute) and an oscillation amplitude of ±0.5°, measuring the minimum torque value (ML), the maximum torque (MH), the time required for the torque to increase by two units (TS2), and the time required to reach different percentages (30%, 60% and 90%) of the maximum torque value (MH).

[0201] Silanization rate Is the percentage of silane that has reacted with silica to the total amount of available silane. Unreacted silane is assessed after the first mixing step. Unreacted silane is removed from the material by dissolving in a solvent. The resulting solution is chemically analyzed to determine the Si-C bond concentration. The amount of Si-C bonds found in the solution is proportional to the amount of unreacted silane. The percent silanization is calculated from the ratio of the concentration of unreacted silane to the concentration of initial silane present in the formulation.

[0202] Properties of vulcanized materials

[0203] The elastomeric materials prepared in the previous examples were vulcanized to obtain samples, which were then subjected to analytical characterization and dynamic mechanical property evaluation. Unless otherwise stated, vulcanization was carried out in a mold, in a hydraulic press, at 170° C. and 200 bar pressure for about 10 minutes.

[0204] Static modulus : Static mechanical properties were measured according to ISO 37:2005 standard at 23° C. In particular, tensile stress, load and elongation at break (CR, AR, respectively) at different elongation levels (100% and 300%, named sequentially CA1 and CA3) were measured on annular specimens of the vulcanized elastomeric composition.

[0205] Dynamic modulus Dynamic mechanical properties were measured using an Instron dynamic device in compression and tension operation according to the following method. Cylindrical vulcanized elastomeric composition samples (height = 25 mm; diameter = 14 mm) were subjected to a dynamic sinusoidal voltage with an amplitude of ±3.5% relative to the preloaded length and a frequency of 100 Hz, the cylindrical vulcanized elastomeric composition samples having a compressive preload with a longitudinal deformation of up to 25% relative to the initial length and maintained at a predetermined temperature (-10° C., 23° C. or 70° C.) during the test.

[0206] The dynamic mechanical properties are expressed in terms of dynamic elastic modulus (E') and Tan delta (loss factor). The Tan delta value is calculated as the ratio between the viscous dynamic modulus (E") and the dynamic elastic modulus (E').

[0207] DIN wear is the amount of complexes removed by operating under the standard conditions given in the DIN 53516 or ISO 4649 standards.

[0208] Normalized wear It is obtained by multiplying the DIN abrasion value by the ratio between the CA3 value of the reference and the CA3 value of the sample in question.

[0209] Example 1

[0210] In this example, a reference compound is compared to a compound of the present invention that includes increasing amounts of triethylenetetramine in place of a portion of the silane coupling agent.

[0211] The elastomeric materials listed in Table 1 below were prepared as follows (the amounts of the various components are in phr).

[0212] In the first step, the elastomer component, white reinforcing filler, silane coupling agent and triethylenetetramine were mixed in an internal mixer (model: Pomini PL1,6) for about 6 minutes until the temperature reached about 135° C. In the second step, the zinc-based component and other protective agents were added and mixing continued for about 4 minutes until the temperature reached about 135° C. Finally, sulfur and other vulcanization additives were added and mixed for another 2 minutes until the temperature reached about 95° C., and then the vulcanizable elastomer compound was discharged.

[0213] Table 1

[0214] Composition ingredients REF1 INV1 INV2 INV3 INV4 INV5 NR 25 25 25 25 25 25 BR 30 30 30 30 30 30 SSBR 62 62 62 62 62 62 Carbon Black 5 5 5 5 5 5 Silicon dioxide 95 95 95 95 95 95 TESPT 7.6 5.9 5.9 5.9 5.9 5.9 TETA - 1.7 1.35 1.0 0.65 0.33 Stearic acid 3 3 3 3 3 3 wax 2 2 2 2 2 2 Resin 1 8 8 8 8 8 8 Resin 2 19 19 19 19 19 19 Zinc Oxide 2.7 2.7 2.7 2.7 2.7 2.7 6PPD 5 5 5 5 5 5 CBS 2 2 2 2 2 2 PVI 0.3 0.3 0.3 0.3 0.3 0.3 sulfur 1 1 1 1 1 1

[0215] NR: Natural Rubber-SIR 20-Standard Indonesian Rubber

[0216] BR: Standard polybutadiene (high cis 97%) - SKD NHEODIMIO - (NizhnekamskneftekhimExport)

[0217] SSBR: Styrene butadiene copolymer, extruded with 37.5 parts of TDAE oil per 100 parts of dry polymer - Microstructure with 24.9% styrene content and 61.7% vinyl content in the butadiene fraction - SPRINTAN TM SLR 4630-Trinseo

[0218] Carbon black: N330 from Cabot Corporation

[0219] Silica: 7000-Evonik

[0220] TESPT: Bis[3-(triethoxysilyl)propyl]tetrasulfide- -Evonik

[0221] TETA: triethylenetetramine -

[0222] Wax: RIOWAX BM-01-Ser SpA

[0223] Resin 1: Polybutadiene- 130-Evonik

[0224] Resin 2: Styrene-butadiene copolymer- 100

[0225] Zinc Oxide: Standard zinc oxide from A-Esse;

[0226] 6PPD: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine SANTOFLEX 6PPD from EASTMAN;

[0227] CBS: N-cyclohexylbenzothiazole-2-sulfenamide RUBENAMID C EG / C from GENERAL QUIMICA.

[0228] Sulfur: Sulfur 98.50% (1% oil) - Zolfindustria

[0229] According to the above method, the vulcanizable elastomeric compound thus prepared was subjected to evaluation of vulcanization behavior (170°C, 30 minutes), and then its static and dynamic mechanical properties and wear resistance were evaluated. Table 2 below shows the rheological, mechanical, dynamic and static characteristics of the composition of Table 1.

[0230] Table 2

[0231]

[0232]

[0233] The Mooney viscosity of the compounds according to the invention is always higher than that of the reference, without however affecting the mixing procedure. The Mooney viscosity tends to rise from the value of the INV1 compound to a maximum value for the INV3 compound, when the triethylenetetramine content is equal to 17%, and then falls back to the value of the INV5 compound, which is almost equal to the value of the INV1 compound.

[0234] The kinetics of the complexes of the present invention are affected by the presence of triethylenetetramine, which Figure 2 It can also be observed in the vulcanization curves of , where the compounds of the invention are observed to have faster kinetics than the reference composition and to show a curve that clearly flattens out to a constant modulus value, in contrast to the curve of the reference composition which shows a typical curve with an increasing modulus.

[0235] For the INV1 compound containing the highest amount of triethylenetetramine, the scorch time as well as the cure kinetics were too fast, but by reducing the amount of triethylenetetramine, both the scorch time and the cure kinetics reached the desired level.

[0236] The silanization level of the INV1 and INV3 composites of the present invention is almost 100%.

[0237] Furthermore, the static mechanical properties increase linearly with the triethylenetetramine content, obtaining values ​​for CA1 and CA3 substantially equal to those of the reference already using the INV4 compound, and obtaining higher values ​​for the CA3 / CA1 ratio, which predicts a better tear resistance and dispersibility of the white filler, which is always superior to that of the reference.

[0238] Finally, the compounds according to the invention show better dynamic mechanical properties than the reference compounds, with lower hysteresis values ​​at 70°C, which indicates a reduced rolling resistance, and equal or slightly higher hysteresis values ​​at 23°C and -10°C, which indicates greater adhesion on wet surfaces and at low temperatures.

[0239] The abrasion, especially the normalized abrasion, remains equal to or slightly better than the reference, with slightly worse values ​​being found only when the amount of triethylenetetramine is greater than 20% relative to the amount of silane coupling agent.

[0240] Example 2

[0241] In this example, a reference compound is compared to a compound of the present invention which includes increasing amounts of triethylenetetramine in addition to a silane coupling agent.

[0242] The elastomeric materials listed in Table 3 below were prepared as follows (the amounts of the various components are in phr).

[0243] In the first step, the elastomer component, white reinforcing filler, silane coupling agent and triethylenetetramine were mixed in an internal mixer (model: Pomini PL 1,6) for about 6 minutes until the temperature reached about 135° C. In the second step, the zinc-based component and other protective agents were added and mixing continued for about 4 minutes until the temperature reached about 135° C. Finally, sulfur and other vulcanization additives were added and mixed for another 2 minutes until the temperature reached about 95° C., and then the vulcanizable elastomer compound was discharged.

[0244] Table 3

[0245] Composition ingredients REF2 OT1 OT2 NR 25 25 25 BR 30 30 30 SSBR 62 62 62 Carbon Black 5 5 5 Silicon dioxide 95 95 95 TESPT 7.6 7.6 7.6 TETA - 0.65 0.33 Stearic acid 3 3 3 wax 2 2 2 Resin 1 8 8 8 Resin 2 19 19 19 Zinc Oxide 2.7 2.7 2.7 6PPD 5 5 5 CBS 2 2 2 PVI 0.3 0.3 0.3 sulfur 0.9 0.9 0.9

[0246] NR: Natural Rubber-SIR20-Standard Indonesian Rubber

[0247] BR: Standard polybutadiene (high cis 97%) - SKD HEODIMIO - Nizhnekamskneftekhim Export)

[0248] SSBR: Styrene butadiene copolymer, extruded with 37.5 parts of TDAE oil per 100 parts of dry polymer - Microstructure with 24.9% styrene content and 61.7% vinyl content in the butadiene fraction - SPRINTAN TM SLR 4630-Trinseo

[0249] Carbon black: N330 from Cabot Corporation

[0250] Silica: 7000-Evonik

[0251] TESPT: Bis[3-(triethoxysilyl)propyl]tetrasulfide- -Evonik

[0252] TETA: triethylenetetramine -

[0253] Wax: RIOWAX BM-01-Ser SpA

[0254] Resin 1: Polybutadiene- 130-Evonik

[0255] Resin 2: Styrene-butadiene copolymer- 100

[0256] Zinc Oxide: Standard zinc oxide from A-Esse;

[0257] 6PPD: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine SANTOFLEX 6PPD from EASTMAN;

[0258] CBS: N-cyclohexylbenzothiazole-2-sulfenamide RUBENAMID C EG / C from GENERAL QUIMICA.

[0259] Sulfur: Sulfur 98.50% (1% oil) - Zolfindustria

[0260] According to the above method, the vulcanization behavior of the elastomer composition thus prepared was evaluated (170°C, 30 minutes), and then its static and dynamic mechanical properties and wear resistance were evaluated. Table 4 below shows the rheological, mechanical, dynamic and static characteristics of the composition of Table 3.

[0261] Table 4

[0262]

[0263]

[0264] By adding triethylenetetramine, the Mooney viscosity decreased slightly, while the scorch time increased, which is the opposite behavior to that seen in Example 1, where triethylenetetramine replaced a portion of the silane coupling agent.

[0265] Figure 3 The curing curve of the compound OT1 according to the invention, as can be seen in the Figure, is not much different from the curve shown in Example 1, showing a clear flattening of the curve at a constant modulus value, while the curve of the compound OT2 according to the invention shows an incremental modulus similar to that of the curve of the reference compound. Both compounds according to the invention have faster kinetics than the reference compound.

[0266] Moreover, using only very small amounts of triethylenetetramine, the static mechanical properties have been significantly improved, higher CA1 and CA3 values ​​have been obtained using the OT2 compound, with a triethylenetetramine content of only 4% compared to the amount of silane coupling agent, and higher CA3 / CA1 ratio values, indicative of tear resistance, have been obtained, which are always better than the reference.

[0267] Finally, the compounds according to the invention show better dynamic mechanical properties than the reference compounds, with lower hysteresis values ​​at 70°C, which indicates a reduced rolling resistance, and the same or slightly higher hysteresis values ​​at 23°C and -10°C, which indicates greater adhesion on wet surfaces and at low temperatures.

[0268] The wear loss is essentially the same as the reference value, while the normalized wear value shows a clear improvement.

[0269] Example 3

[0270] In this example, a reference compound (REF BR) comprising a different polymer compound (consisting only of SSBR and BR) is compared with a compound of the present invention (a compound comprising an amount of triethylenetetramine in addition to a silane coupling agent (OT BR), and a compound comprising an amount of triethylenetetramine replacing a portion of the silane coupling agent (INV BR)).

[0271] The elastomeric materials listed in Table 5 below were prepared as follows (the amounts of the various components are in phr).

[0272] In the first step, the elastomer component, white reinforcing filler, silane coupling agent and triethylenetetramine were mixed in an internal mixer (model: Pomini PL 1,6) for about 6 minutes until the temperature reached about 135° C. In the second step, the zinc-based component and other protective agents were added and mixing continued for about 4 minutes until the temperature reached about 135° C. Finally, sulfur and other vulcanization additives were added and mixed for another 2 minutes until the temperature reached about 95° C., and then the vulcanizable elastomer compound was discharged.

[0273] Table 5

[0274]

[0275]

[0276] SSBR: Styrene butadiene copolymer, extruded with 37.5 parts of TDAE oil per 100 parts of dry polymer - Microstructure with 24.9% styrene content and 61.7% vinyl content in the butadiene fraction - SPRINTAN TM SLR 4630-Trinseo

[0277] BR: Standard polybutadiene (high cis 97%) - SKD HEODIMIO - (NizhnekamskneftekhimExport)

[0278] Carbon black: N330 from Cabot Corporation

[0279] Silica: 7000-Evonik

[0280] TESPT: Bis[3-(triethoxysilyl)propyl]tetrasulfide- -Evonik

[0281] TETA: triethylenetetramine -

[0282] Wax: RIOWAX BM-01-Ser SpA

[0283] Resin 1: Polybutadiene- 130-Evonik

[0284] Resin 2: Styrene-butadiene copolymer- 100

[0285] Zinc Oxide: Standard zinc oxide from A-Esse;

[0286] 6PPD: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine SANTOFLEX 6PPD from EASTMAN;

[0287] CBS: N-cyclohexylbenzothiazole-2-sulfenamide RUBENAMID C EG / C from GENERAL QUIMICA.

[0288] Sulfur: Sulfur 98.50% (1% oil) - Zolfindustria

[0289] According to the above method, the vulcanization behavior of the elastomer composition thus prepared was evaluated (170°C, 30 minutes), and then its static and dynamic mechanical properties and wear resistance were evaluated. Table 6 below shows the rheological, mechanical, dynamic and static characteristics of the composition of Table 6.

[0290] Table 6

[0291]

[0292]

[0293] From the tests carried out it can be seen that the vulcanization kinetics are improved for both the INV BR and the OT BR compounds according to the invention.

[0294] The kinetics are accelerated, on the one hand due to the shorter scorch times, which however never reach very low levels, especially for the INV BR compounds, and on the other hand due to the vulcanization curve ( Figure 4 ) also show that in the early stages of vulcanization, the constant modulus values ​​tend to be flat and the kinetics are faster, which is more obvious for the INV BR compound.

[0295] The static mechanical properties of the compounds of the invention (INV BR and OT BR) show similar improvements as the use of triethylenetetramine in compounds with three elastomeric polymers. In fact, higher Ca3 values ​​are obtained in both cases, as well as higher Ca3 / Ca1 ratios, indicating better tear resistance and dispersibility of the white filler.

[0296] Also in this case, as in the previous example, there is an improvement in the dynamic mechanical properties.

[0297] In the compounds of the invention (INV BR and OT BR) there is the fact that the hysteresis values ​​at low temperatures (-10°C and 23°C) are increased, indicating a better performance in wet conditions, but at the same time the hysteresis values ​​at high temperatures (70°C) are lower, indicating a lower rolling resistance and therefore a higher efficiency of the tire from the point of view of fuel consumption.

[0298] Finally, considering the pure mass loss in the DIN wear test, the wear is already reduced, and there is a further improvement if one instead considers the normalized wear which takes into account the greater stiffness represented by the value of Ca3.

[0299] Example 4

[0300] In this example, a reference compound (REF NR) comprising a different polymer compound (consisting only of SSBR and NR) is compared with the compounds of the present invention (a compound comprising an amount of triethylenetetramine in addition to a silane coupling agent (OTNR); and a compound comprising an amount of triethylenetetramine replacing a portion of the silane coupling agent (INV NR)).

[0301] The elastomeric materials listed in Table 7 below were prepared as follows (the amounts of the various components are in phr).

[0302] In the first step, the elastomer component, white reinforcing filler, silane coupling agent and triethylenetetramine were mixed in an internal mixer (model: PominiPL1,6) for about 6 minutes until the temperature reached about 135°C. In the second step, the zinc-based component and other protective agents were added and mixing continued for about 4 minutes until the temperature reached about 135°C. Finally, sulfur and other vulcanization additives were added and mixed for another 2 minutes until the temperature reached about 95°C, and then the vulcanizable elastomer compound was discharged.

[0303] Table 7

[0304] Composition ingredients REF BR INV BR OT BR NR 42 42 42 SSBR 80 80 80 Carbon Black 5 5 5 Silicon dioxide 95 95 95 TESPT 7.6 5.9 7.6 TETA - 1 0.65 Stearic acid 3 3 3 wax 2 2 2 Resin 1 8 8 8 Resin 2 19 19 19 Zinc Oxide 2.7 2.7 2.7 6PPD 5 5 5 CBS 2 2 2 PVI 0.3 0.3 0.3 sulfur 0.9 0.9 0.9

[0305] NR: Natural Rubber-SIR20-Standard Indonesian Rubber

[0306] SSBR: Styrene butadiene copolymer, extruded with 37.5 parts of TDAE oil per 100 parts of dry polymer - Microstructure with 24.9% styrene content and 61.7% vinyl content in the butadiene fraction - SPRINTAN TM SLR 4630-Trinseo

[0307] Silica: 7000-Evonik

[0308] TESPT: Bis[3-(triethoxysilyl)propyl]tetrasulfide- -Evonik

[0309] TETA: triethylenetetramine -

[0310] Wax: RIOWAX BM-01-Ser SpA

[0311] Resin 1: Polybutadiene- 130-Evonik

[0312] Resin 2: Styrene-butadiene copolymer- 100

[0313] Carbon black: N330 from Cabot Corporation

[0314] Zinc Oxide: Standard zinc oxide from A-Esse;

[0315] 6PPD: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine SANTOFLEX 6PPD from EASTMAN;

[0316] CBS: N-cyclohexylbenzothiazole-2-sulfenamide RUBENAMID C EG / C from GENERAL QUIMICA.

[0317] Sulfur: Sulfur 98.50% (1% oil) - Zolfindustria

[0318] According to the above method, the vulcanization behavior of the elastomer composition thus prepared was evaluated (170°C, 30 minutes), and then its static and dynamic mechanical properties and wear resistance were evaluated. Table 8 below shows the rheological, mechanical, dynamic and static characteristics of the composition of Table 8.

[0319] Table 8

[0320]

[0321]

[0322] Also in this context, the tests carried out showed that the vulcanization kinetics were improved for both the INV NR and OT NR compounds according to the invention.

[0323] The kinetics are accelerated, on the one hand due to the shorter scorch time, which, however, does not reach very low levels in any case, especially for the INV NR compound, and on the other hand due to the vulcanization curve ( Figure 5 ) also show that in the early stage of vulcanization, the constant modulus value tends to be flat while the kinetics are faster, which is particularly evident for the INV NR composite.

[0324] The static mechanical properties of the INV NR and OT NR composites of the present invention show similar improvements to those seen with triethylenetetramine in composites with three polymers. In fact, higher Ca3 values ​​are obtained in both cases, as well as higher Ca3 / Ca1 ratios, indicating better tear resistance and dispersion of the white filler.

[0325] Also in this case, as in the previous example, there is an improvement in the dynamic mechanical properties.

[0326] The inventive (INV NR and OT NR) composites have hysteresis values ​​at low temperature (23°C) higher than or in line with the reference, indicating good performance in wet conditions, but at the same time have lower hysteresis values ​​at high temperature (70°C), indicating lower rolling resistance and therefore more efficient tire from a fuel consumption point of view.

[0327] Finally, the wear is almost the same as that of the reference, especially the normalized wear of the OT NR composite is slightly improved.

Claims

1. A tire comprising at least one structural element comprising a vulcanized elastomeric material obtained by vulcanizing a vulcanizable elastomeric compound, the vulcanizable elastomeric compound being obtained by mixing an elastomeric composition comprising, per 100 phr of a diene elastomeric polymer: (a) 30 to 95 phr of at least one styrene-butadiene polymer (SBR); (b) 5 to 70 phr of at least one diene elastomeric polymer chosen from the group consisting of at least one isoprene polymer (IR), at least one butadiene polymer (BR) or mixtures thereof; (c) 10 to about 120 phr, preferably 20 to 100 phr, of at least one white reinforcing filler; (d) from about 1% to about 20% by weight of at least one silane coupling agent relative to the amount of the white reinforcing filler; (e) 1 to 35%, preferably 5 to 25% by weight of a polyamine relative to the amount of the silane coupling agent.

2. The tire according to claim 1, wherein: The elastomeric composition comprises, per 100 phr of diene elastomeric polymer: (a) 40 to 70 phr of at least one styrene-butadiene polymer (SBR); (b) 10 to 40 phr of at least one isoprene polymer (IR); and (c) 20 to 50 phr of at least one butadiene polymer (BR).

3. The tire according to claim 1, wherein: The elastomeric composition comprises, per 100 phr of diene elastomeric polymer: (a) 50 to 80 phr of at least one styrene-butadiene polymer (SBR); and (b) 20 to 50 phr of at least one butadiene polymer (BR).

4. The tire according to claim 1, wherein: The elastomeric composition comprises, per 100 phr of diene elastomeric polymer: (a) 50 to 80 phr of at least one styrene-butadiene polymer (SBR); and (b) 20 to 50 phr of at least one isoprene polymer (IR).

5. The tire according to claim 1, wherein: The polyamine is represented by the following structural formula (IV): wherein x is an integer of 2 to 6, R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Alk is a divalent straight-chain alkylene group having 1 to 8 carbon atoms.

6. The tire according to claim 1, wherein: The polyamine is selected from the group consisting of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, heptaethyleneoctamine, dipropylenetriamine, tripropylenetetramine, tetrapropylenepentamine, dibutylenetriamine, tributylenetetramine, tetrabutylenepentamine, dimethylenetriamine, trimethylenetetramine, tetramethylenepentamine, pentamethylenehexamine, di(heptamethylene)triamine, di(trimethylene)triamine, decaethylenedecamine, decamethylenedecamine, N,N-dimethyldiethylenetriamine, N,N-dimethyltetraethylenepentamine, N,N-diethyltetraethylenepentamine, N,N',N"-trimethyldiethylenetriamine, dipentenetriamine, trienetetramine, tetraheptenepentamine, trioctenenetetramine and tetrapentenepentamine.

7. The tire according to claim 1, wherein: The polyamine is selected from the group consisting of trimethylenetetramine, triethylenetetramine and tripropylenetetramine, preferably triethylenetetramine.

8. The tire according to claim 1, wherein: The tire comprises: - a carcass structure having opposite side edges associated with respective left and right bead structures; - a tread band applied in a radially outer position with respect to said carcass structure; - a pair of sidewalls applied laterally on opposite sides of said carcass structure; Therein, the structural element is at least one of the tread band or the pair of sidewalls.

9. An elastomeric composition comprising, per 100 phr of diene elastomeric polymer: (a) 30 to 95 phr of at least one styrene-butadiene polymer (SBR); (b) 5 to 70 phr of at least one diene elastomeric polymer chosen from the group consisting of at least one isoprene polymer (IR), at least one butadiene polymer (BR) or mixtures thereof; (c) 10 to about 120 phr, preferably 20 to 100 phr, of at least one white reinforcing filler; (d) from about 1% to about 20% by weight of at least one silane coupling agent relative to the amount of the white reinforcing filler; (e) 1 to 35%, preferably 5 to 25% by weight of a polyamine relative to the amount of the silane coupling agent.

10. The elastomer composition according to claim 9, wherein The elastomeric composition comprises the components as defined in claims 2 to 7.

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