Methods for preparing tire compounds and tires containing them

Abstract

The present invention relates to a compound represented by formula (II): WF-O-ROS-GC-Fe (II) [wherein WF represents a white filler, O represents one or more oxygen bridges, ROS represents an organosilane residue, GC represents one or more ligands that form a chelate with ionic iron, and Fe represents ionic iron (Fe 3+ ) coordinated with the ligand] and to a method for its preparation and its use in the vulcanization process of elastomeric compounds.

Description

Technical Field

[0001] The present invention relates to a method for preparing an elastomeric compound for tires that can be effectively vulcanized without the introduction of zinc, characterized by the incorporation of specific modified fillers capable of activating vulcanization.

Background Art

[0002] In the tire industry, vulcanization is a process commonly used to improve the mechanical properties of natural rubber or unsaturated polymers, affecting the hardness, elasticity, hysteresis of the material at different temperatures, and as a result, the behavior of wet tires and their friction and wear during use.

[0003] Over the years, various additives have been proposed to improve the vulcanization process as vulcanization activators and accelerators.

[0004] Generally, it is desired to use these additives to increase the degree and homogeneity of crosslinking while reducing the energy and time required to complete the reaction.

[0005] The main vulcanization activators that can increase the efficiency of the process are inorganic compounds such as metal oxides and hydroxides, for example, ZnO, MgO, Ca(OH)2.

[0006] Among various activators, zinc oxide ZnO is considered the most efficient and is still used in many vulcanization processes today. This activator is used in combination with a weak organic acid (such as stearic acid) that promotes its activity in rubber.

[0007] The poor dispersibility and reactivity of microcrystalline zinc oxide in elastomeric compounds inevitably lead to its overdosage with respect to the amount actually required for crosslinking.

[0008] Since zinc can pollute land and water used for agricultural purposes and is associated with accumulation phenomena that can cause serious damage to animal and plant species and ultimately to humans, attempts have been made over the years to reduce the amount of zinc in the compound and thus the amount dispersed in the environment by the normal wear of tires.

[0009] Initially, Zn was synthesized by the terminal amino group. 2+ It has been shown to be advantageous to use materials in which the silica surface is functionalized with aminosilanes, such as 3-aminopropyl-triethoxysilane (APTES), which are bonded to the silica surface by covalent bonds of the Si-O-Si type, leading to coordination with ZnO. The application of these new materials in the vulcanization process of elastomeric compounds has demonstrated higher vulcanization efficiency and better crosslink density compared to conventionally used ZnO activators, as described in WO2020 / 110023 in the name of the applicant and in S. Mostoni et al., "Design of a Zn Single-Site Curing Activator for a More Sustainable Sulfur Cross-Link Formation in Rubber", Ind. Eng. Chem. Res. 2021, 60, 10180-10192.

[0010] Later, research was carried out on the use of other metal oxides (such as CaO, MgO, BaO, BeO, and CuO) as activators for the vulcanization of EPDM and SBR rubbers in place of zinc oxide in an attempt to completely replace the use of zinc (Lautenschlaeger, fk; Edwards, k. Model compound vulcanisation-part V. The effect of chemical additives and fillers. Rubber Chem. Technol. 1979; Vol. 53; 27-47).

[0011] Other studies conducted to compare the catalytic activity of calcium oxide and magnesium oxide in the vulcanization reaction have shown that when calcium oxide is used as an activator, the kinetics are slower and a lower degree of crosslinking is achieved. Instead, when magnesium oxide is used instead of ZnO, the accelerator reacts with good kinetics in the first stage of the vulcanization reaction, but in this case too, a lower crosslink density is reached than that obtained with zinc oxide. In this case, zinc oxide remains the best activator, providing a high degree of crosslinking (Roy, K.; Alam, M. N.; Mandal, S. K.; Debnath, S. C. Preparation of zinc-oxide-free natural rubber nanocomposites using nanostructured magnesium oxide as cure activator. J. Appl. Polym. Sci. 2015, 132, 1 - 7); (Guzman, M.; Vega, B.; Agullo, N.; Giese, U.; Borros, S. Zinc oxide versus magnesium oxide revisited. Part 1. Rubber Chem. Technol. 2012, 85, 38 - 55;)(Guzman, M.; Vega, B.; Agullo, N.; Borros, S. Zinc Oxide Versus Magnesium Oxide Revisited. Part 2. Rubber Chem. Technol, 2012, 85, 56 - 67).

[0012] Some studies have used iron, particularly iron oxide, in elastomer compounds to impart some specific properties such as magnetic, electrical or conductive properties to the final material or to influence the crosslinking reaction.

[0013] El-Nashar et al. [J Mater Sci (2006) 41, 5359 - 5364] prepared composites with good mechanical, magnetic and electrical properties by mixing different concentrations of magnetic Fe nanoparticles as fillers with a natural rubber matrix to form composites for various applications.

[0014] Bellucci et al. [Composites Part B: Engineering, Vol. 85 (2016) 196 - 206] studied the influence of the size, shape, and concentration of ferrite nanoparticles on the magnetic properties of natural rubber nanocomposites.

[0015] Smejda - Krzewicka et al. [Iranian Polymer Journal (2019) 28: 313 - 323] studied the effect of iron(III) oxide (Fe2O3) in the cross - linking process of chloroprene - butadiene rubber compounds (CR / BR) and observed that the obtained CR / BR / Fe2O3 vulcanizates are characterized by good mechanical properties, a higher curing rate, and high fire resistance.

[0016] Dziemidkiewicz et al. [Journal of Thermal Analysis and Calorimetry (2019) 138: 4395 - 4405] studied the activity of metal acetylacetonates, especially iron acetylacetonate, as vulcanizing agents for brominated isobutylene - isoprene rubber (BIIR) based on the Heck reaction.

[0017] Tantawy et al. (Polym Int 49, 1670 - 1676 (2000)) studied the effect of iron oxide (Fe3O4) combined with zinc oxide and carbon black on the vulcanization process of isobutylene - isoprene rubber (IIR) by measuring DC conductivity, thermopower, dielectric constant, and I - V characteristics. Summary of the Invention

[0018] The applicant of the present application aimed to eliminate zinc incorporated in the compound without causing any deterioration or further improvement in their performance compared to equivalent conventional compounds, which brings important environmental benefits, and initiated research to further improve the effectiveness of activating fillers in the production of compounds for tires.

[0019] Surprisingly, the applicant found that ionic iron Fe 3+It has been found that it can be bonded to the surface of the white filler via a coupling agent containing a reactive group capable of bonding to the surface of the white filler, particularly capable of forming an oxygen bridge, and a coordinating group capable of chelating ionic iron, to particles of the white filler, such as silica nanoparticles.

[0020] Therefore, the coupling agent has the following formula (I): GR-ROS-GC (I) [wherein GR represents one or more reactive groups capable of bonding to the surface of the white filler via the formation of an oxygen bridge (-O-), ROS represents an organosilane residue, and GC represents one or more coordinating groups] can be schematized by.

[0021] Moreover, the material produced by the applicant can thus be represented by the following formula (II): WF-O-ROS-GC-Fe (II) [wherein the reactive group GR reacts with the surface of the white filler (WF) to form an oxygen bridge (-O-) with the organosilane residue (ROS), and then the coordinating group GC chelates ionic iron] can be schematized by.

[0022] The applicant has surprisingly found that such materials provide various advantages when used in the vulcanization process of compounds used in the production of tires.

[0023] Advantageously, the use of such materials makes ionic iron readily available, thereby forming organometallic complexes more rapidly and efficiently.

[0024] The applicant has observed that the use of such materials allows for the use of lower mixing temperatures since it does not require the use of silanes to maximize the integrity of the material and the preparation cost of the elastomeric compound subjected to vulcanization.

[0025] Furthermore, Applicant has observed that such materials enable faster vulcanization times and better mechanical properties of the resulting vulcanized materials.

[0026] A further advantage observed by Applicant consists of the fact that it eliminates the use of zinc in the tire vulcanization process, which has clear advantages from an environmental point of view.

[0027] Thus, a first aspect of the invention is a compound represented by the following formula (II): WF-O-ROS-GC-Fe (II) wherein, WF represents a white filler, O represents one or more oxygen bridges, ROS represents an organosilane residue, GC represents one or more ligands that form a chelate with ionic iron, and Fe represents ionic iron (Fe coordinated with the ligand) 3+ ) is.

[0028] A second aspect of the invention is a method for the preparation of a compound represented by formula (II) of the first aspect of the invention, comprising: · providing a white filler (WF); · providing a coupling agent having the following formula (I): GR-ROS-GC (I) wherein, GR represents one or more reactive groups capable of forming an oxygen (-O-) bridge with the surface of the white filler, ROS represents an organosilane residue, and GC represents one or more ligands; · providing an ionic iron precursor (Fe 3+ ) · reacting the white filler (WF) with one or more reactive groups (GR) of the compound of formula (I) to form an oxygen (-O-) bridge between the white filler and the organosilane residue (ROS); · coordinating one or more ligands (GC) of the compound of formula (I) with the ionic iron precursor (Fe 3+ ​) and a step of reacting to form a chelate, · a step of separating the obtained compound of formula (II) WF-O-ROS-GC-Fe which is represented by a method comprising at least.

[0029] A third aspect of the present invention is a method for preparing a vulcanizable elastomer compound for a tire, · a mixing step (1) of at least one elastomer polymer and at least one additive for an elastomer compound other than a vulcanizing agent to obtain a non-vulcanizable elastomer compound, · a mixing step (2) of the non-vulcanizable elastomer compound and at least one vulcanizing agent to obtain a vulcanizable elastomer compound, · a step of taking out the vulcanizable elastomer compound and comprising at least In at least one of the mixing steps (1) and (2), a compound according to the first aspect of the present invention is added, which is represented by a method.

[0030] A fourth aspect of the present invention is represented by a vulcanizable elastomer compound obtained according to the method of the third aspect of the present invention.

[0031] A fifth aspect of the present invention is a tire component comprising the vulcanizable compound of the fourth aspect of the present invention or a vulcanized compound obtained by vulcanizing the same.

[0032] A sixth aspect of the present invention is a tire for a vehicle wheel comprising a component according to the fifth aspect of the present invention.

[0033] Definitions For the purposes of this specification and the following claims, the term "phr" (parts per hundred parts by weight of rubber) means parts by weight of a given component of an elastomer composition based on 100 parts by weight of a diene elastomer polymer.

[0034] Unless otherwise indicated, all percentages are expressed as weight percentages.

[0035] As used herein, the terms "elastomeric polymer" or "rubber" or "elastomer" mean a natural or synthetic polymer that, after vulcanization, can be repeatedly stretched at room temperature to at least twice its original length and, substantially immediately after removal of the tensile load, forcibly returns to approximately its original length (according to the definition of standard terms for rubber in ASTM D1566-11).

[0036] As used herein, the term "reinforcing filler" refers to a filler typically used in the sector to improve the mechanical properties of tire rubber, preferably selected from carbon black, conventional silica, e.g., silica from sand precipitated with strong acid, preferably amorphous, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicate, kaolin, silicate fiber, and mixtures thereof.

[0037] As used herein, the term "white filler" refers to a conventional reinforcing material used in the sector, typically selected from conventional silica and silicates, optionally modified and / or derivatized by acid treatment, e.g., sepiolite, palygorskite, also known as attapulgite, montmorillonite, allophane, etc. Typically, white fillers have surface hydroxyl groups.

[0038] As used herein, the term "reactive group" refers to a group that can react with the surface hydroxyl groups of a white filler to eliminate water or alcohol and form an oxygen bridge (-O-), typically a hydroxyl group (-OH) or an alkoxy group (-OR) [wherein R represents a straight-chain or branched alkyl chain having 1 to 6 carbon atoms].

[0039] As used herein, the term "organosilane residue" means a residue containing at least one straight-chain or branched alkyl chain having 1 to 6 carbon atoms bonded to a silicon atom.

[0040] As used herein, the term "ligand" refers to a functional group containing an atom that can form a coordinate bond with ionic iron Fe, such as nitrogen, oxygen, or sulfur. 3+ and the like.

[0041] As used herein, the term "precursor of ionic iron (Fe 3+ )" refers to a compound selected from Fe2O3, Fe(OH)3, and organic or inorganic salts of Fe 3+ .

[0042] As used herein, the term "elastomer compound" is a product obtained by mixing at least one elastomer polymer with at least one of the additives commonly used in the preparation of tire compounds and optionally heating.

[0043] As used herein, the term "non-vulcanizable elastomer compound" means a product obtained by mixing at least one elastomer polymer with at least one of the additives commonly used in the preparation of tire compounds other than a vulcanizing agent. A non-vulcanizable elastomer compound may also be referred to as a phase (1) elastomer compound.

[0044] As used herein, the term "vulcanizable elastomer compound" means an elastomer compound that is ready for vulcanization with all additives including a vulcanizing agent incorporated therein. A vulcanizable elastomer compound may also be referred to as a phase (2) elastomer compound.

[0045] As used herein, the term "vulcanized elastomer compound" means a material obtained by vulcanizing a vulcanizable elastomer compound.

[0046] As used herein, the term "mixing step (1)" refers to the step of the production process of an elastomeric compound in which one or more additives, excluding the vulcanizing agent fed in step (2), can be incorporated by mixing and optionally heating.

[0047] As used herein, the term "mixing step (2)" refers to the subsequent step of the production process of an elastomeric compound in which a vulcanizing agent as well as preferably a vulcanization accelerator and / or retarder are incorporated into and mixed in the material at a controlled temperature, generally a mixing temperature lower than 160 °C.

[0048] Mixing step (1) is also referred to as a "non-productive step" because the components of the compound, excluding the crosslinking agents (e.g., sulfur and accelerators), are fed to the mixing device.

[0049] Mixing step (2), on the contrary, is referred to as a productive step. In this step, the elastomeric compound obtained from step (1) as well as the vulcanization additives that can support and / or control crosslinking are fed to the mixing device so as to provide a vulcanizable elastomeric compound.

[0050] As used herein, the term "green" is generally used to refer to a material, compound, composition, component or tire that has not yet been vulcanized.

Brief Description of the Drawings

[0051]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0052] The method for the preparation of the compound of formula (II) according to the present invention is illustrated in detail below.

[0053] This method is one or more of the following preferred embodiments, listed alone or in combination with each other, particularly the following formula (I): GR-ROS-GC (I) [wherein, GR represents one or more reactive groups, ROS represents an organosilane residue, and GC represents one or more coordinating groups] characterized by the use of a coupling agent having the same.

[0054] The method of the present invention · Step of preparing a white filler (WF), · The following formula (I): GR-ROS-GC (I) [wherein, GR represents one or more reactive groups capable of forming an oxygen (-O-) bridge with the surface of the white filler, ROS represents an organosilane residue, and GC represents one or more coordinating groups] · Step of preparing a coupling agent having the same, · Step of preparing an ionic iron precursor (Fe 3+ ) · Reacting the white filler (WF) with one or more reactive groups (GR) of the compound of formula (I) so as to form an oxygen (-O-) bridge between the white filler and the organosilane residue (ROS), · One or more coordinating groups (GC) of the compound of formula (I) with an ionic iron precursor (Fe 3+) and a step of reacting to form a chelate, · a step of separating the obtained compound of formula (II) WF-O-ROS-GC-Fe and at least includes.

[0055] The white filler can be any conventional white reinforcing filler having hydroxyl groups on its surface.

[0056] The white filler is preferably selected from conventional silicas and silicates in the form of fibers, flakes or granules, optionally modified and / or derivatized by acid treatment, such as bentonite, nontronite, beidellite, volkonskoite, hectorite, saponite, sauconite, vermiculite, sericite, sepiolite, palygorskite also known as attapulgite, montmorillonite, allophane, etc., and mixtures thereof, and more preferably it is silica.

[0057] The silica may vary in shape, specific surface area and size.

[0058] Examples of silica are calcined silica, precipitated amorphous silica, wet silica (hydrated silicic acid), or mixtures thereof.

[0059] Examples of suitable commercially available silicas are precipitated silica Rhodia Zeosil® MP1165 (BET specific surface area 160 m 2 / g), Ultrasil® VN3 GR (BET specific surface area 180 m 2 / g) and Zeosil® 1115 MP (BET specific surface area 95 - 120 m 2 / g).

[0060] Preferably, the silica has a specific surface area (BET) of at least 120 m 2 / g, more preferably at least 140 m 2 / g.

[0061] Preferably, the silica is 220 m2 smaller than / g, more preferably 180 m 2 and has a specific surface area (BET) of 180 m / g or less.

[0062] Useful examples of the compounds represented by formula (I) are alkoxysilanes functionalized with one or more functional groups containing heteroatoms, where the alkoxy group represents a reactive group GR capable of bonding to the white filler, and the functional group containing a heteroatom represents a coordinating group GC capable of forming a coordination bond with ionic iron (Fe 3+ ).

[0063] Preferred examples of the reactive group GR are alkoxy groups having 1 to 4 carbon atoms, namely methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, and tert-butoxy groups.

[0064] Preferred examples of the GC coordinating group represented by the functional group containing a heteroatom are linear or branched alkyl chains containing one or more heteroatoms in the alkyl chain or at the end, for example, for example, the formula -C n H 2n -XC m H 2m -Y or -C m H 2m -Y [wherein equal or different n and m are integers from 1 to 6 (including 1 and 6), X is a group selected from mercapto and amino, and Y is a group selected from mercapto, amino, dithiocarbamate, and carboxyl].

[0065] Useful examples of the compounds represented by formula (I) are the following general formulas (Ia) and (Ib): (R)3Si-C n H 2n -X-C m H 2m -Y (Ia) (R)3Si-C m H 2m -Y (Ib) [In the formula, the equal or different R groups 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, the equal or different n and m are integers from 1 to 6 (including 1 and 6), X is a group selected from mercapto and amino, and Y is a group selected from mercapto, amino, dithiocarbamate, and carboxylic] represented by

[0066] Compounds that can be used in the present invention are (3-aminopropyl)triethoxysilane (APTES), N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (also known as N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDTMS)), N-(2-aminoethyl)-3-aminopropyl-triethoxysilane, N-(2-aminoethyl)-3-aminopropyl-methyl-dimethoxysilane, 3-aminopropylmethyl-diethoxysilane, 3-ureidopropyl-trimethoxysilane, 3-ureidopropyl-triethoxysilane, N-cyclohexyl(aminomethyl)methylthoxysilane, N-cyclohexyl(aminomethyl)triethoxysilane, N-cyclohexyl-3-aminopropyl-trimethoxysilane, 3-(2-aminomethylamino)propyl-triethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminoisobutyl-methyl-dimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-(2-(2-aminoethylamino)ethylamino)propyl-trimethoxysilane, N-(n-butyl)-3-aminopropyl-triethoxysilane, Ν,Ν-diethylaminopropyl-trimethoxysilane, N,N-dimethylaminopropyl-trimethoxysilane, butylaminomethyl-triethoxysilane, N-cyclohexyl(aminomethyl)trimethoxysilane, 2-aminoethylaminomethyl-triethoxysilane, diethylaminomethyl-triethoxysilane, (3-mercaptopropyl)triethoxysilane and (3-mercaptopropyl)trimethoxysilane.

[0067] Preferred compounds are (3-mercaptopropyl)trimethoxysilane, (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.

[0068] Ionic iron (Fe 3+ ) precursors are Fe2O3, Fe(OH)3, and Fe in anhydrous or hydrated forms 3+ organic or inorganic salts, such as, for example, ferric nitrate, ferric sulfate, ferric carbonate, ferric chloride, ferric bromide, ferric iodide, ferric fluoride, ferric phosphate, ferric acetate, ferric oxalate, ferric citrate, ferric gluconate, ferric fumarate, ferric lactate, etc.

[0069] The reaction step between the white filler and the coupling agent of formula (I) is carried out while hot in the solvent phase by first dispersing the white filler in a suitable solvent and then adding the coupling agent and reacting it until the reaction is complete.

[0070] The solvent used in the reaction is preferably selected from the group of non-polar solvents such as hexane, cyclohexane, benzene, and toluene.

[0071] Optionally, the white filler is first activated by dispersion in a basic aqueous solution such as a sodium hydroxide solution. The activation of the white filler is carried out at room temperature in the range of 20°C to 30°C for a period of at least 1 hour, more preferably at least 3 hours, even more preferably at least 6 hours. The activation period is preferably less than 48 hours, more preferably less than 36 hours. Advantageously, the activation period is in the range between 12 and 24 hours. The white filler thus activated is separated by conventional separation techniques (filtration, centrifugation, etc.) and then subjected to lyophilization.

[0072] The reaction between the white filler and the coupling agent is preferably carried out at a temperature higher than 40°C, more preferably higher than 60°C, even more preferably higher than 80°C. The reaction temperature is preferably lower than 200°C, more preferably lower than 180°C, even more preferably lower than 160°C.

[0073] The reaction between the white filler and the coupling agent is preferably carried out at the reflux temperature of the reaction mixture for a period of at least 1 hour, more preferably at least 3 hours, even more preferably at least 6 hours. The reaction period is preferably less than 48 hours, more preferably less than 36 hours. Advantageously, the reaction period is in the range between 12 and 24 hours.

[0074] The reaction product represented by the functionalized white filler is separated by conventional separation techniques (filtration, centrifugation, etc.) and then dried at a temperature between 60°C and 100°C.

[0075] The functionalized white filler, which can be represented by the formula WF-O-ROS-GC, is then reacted with an ionic iron precursor (Fe 3+ ) to form a chelate represented by formula (II).

[0076] The reaction is carried out by first dispersing the functionalized white filler (WF-O-ROS-GC) in a suitable solvent and then an ionic iron precursor such as (Fe 2( SO4)3*xH2O (Fe3+ ) is added and reacted until the reaction is complete, which is carried out while it is hot in the solvent phase.

[0077] The solvent used in the reaction is preferably selected from the group of polar protic solvents such as ethanol, methanol and isopropanol.

[0078] The reaction is preferably carried out at a temperature higher than 40 °C, more preferably higher than 60 °C, even more preferably higher than 80 °C. The reaction temperature is preferably lower than 200 °C, more preferably lower than 180 °C, even more preferably lower than 160 °C.

[0079] The reaction is preferably carried out at the reflux temperature of the reaction mixture for a period of at least 10 minutes, more preferably at least 30 minutes, even more preferably at least 1 hour. The reaction period is preferably less than 12 hours, more preferably less than 6 hours. Advantageously, the reaction period is in the range between 2 and 4 hours.

[0080] The reaction product represented by formula (II) according to the present invention is separated by conventional separation techniques (filtration, centrifugation, etc.) and then dried at a temperature between 60 °C and 100 °C.

[0081] A method for preparing a vulcanizable elastomer compound for tires according to the present invention is illustrated in detail below.

[0082] This method is characterized by the use of one or more of the following preferred embodiments, listed alone or in combination with each other, in particular the following formula (II): WF-O-ROS-GC-Fe (II) [wherein WF represents a white filler, O represents one or more oxygen bridges, ROS represents an organosilane residue, GC represents one or more ligands that form a chelate with ionic iron, and Fe represents ionic iron coordinated with the ligand (Fe 3+ )] characterized by the use of a compound represented by.

[0083] The method of the present invention can be a continuous process, but preferably it is a discontinuous process (batch).

[0084] When the method of the present invention is discontinuous, it can be carried out in one or more mixers, preferably in a single mixer.

[0085] The method according to the present invention includes a mixing step (step 1) of at least one diene elastomer polymer and at least one additive for an elastomer compound that is not a vulcanizing agent.

[0086] At least one additive for an elastomer compound mixed with at least one diene elastomer polymer in the mixing step (1) can be, for example, a compound of formula (II) of the present invention, a reinforcing filler, an antioxidant, a wax, a plasticizer, etc.

[0087] Generally, in the mixing step (1), no vulcanizing agent is added, and preferably, not even a vulcanization accelerator or retarder is added.

[0088] In the method of the present invention, in the mixing step (1), the compound of formula (II) of the present invention can be fed in whole or in part.

[0089] Preferably, the compound of formula (II) of the present invention is fed entirely in step (1).

[0090] In step (1), the mixing is generally carried out at a mixing temperature between 70°C and 160°C, typically for a time between 2 and 20 minutes.

[0091] Before proceeding to step (2), it may be advantageous to carry out a step of discharging and / or resting the non-vulcanized elastomer compound in order to allow completion of any reaction.

[0092] Preferably, the compound of step (1) is discharged before proceeding to step (2).

[0093] In subsequent step (2), at least one vulcanizing agent is incorporated. Optionally, in step (2), at least one vulcanization accelerator, at least one vulcanization retarder, and, if not already fully fed in mixing step (1), the compound of formula (II) of the present invention can be added.

[0094] In step (2) of the process of the present invention, the mixing temperature is generally maintained below 160°C, preferably 140°C, more preferably 120°C, so as to avoid any undesirable pre-crosslinking phenomena.

[0095] Generally, in step (2), the mixing can be carried out at a mixing temperature between 70°C and 155°C for a time between 2 and 10 minutes.

[0096] At the end of step (2), the process of the present invention involves a step of removing the vulcanizable elastomer compound, which will be defined as subsequent typical processing steps for the production of tires and their components.

[0097] In one or more of the steps of the process of the present invention, other additives commonly used in the production of tire compounds, selected based on the specific intended use of the composition, can be added. For example, the following can be added: anti-aging agents, plasticizers, adhesives, anti-ozone agents, modified resins, or mixtures thereof.

[0098] In the process of the present invention, at least one diene elastomer polymer can be selected from those commonly used in sulfur-vulcanizable elastomer compositions that are particularly suitable for producing tires, i.e., generally elastomer polymers or copolymers having unsaturated chains with a glass transition temperature (Tg) lower than 20°C, preferably in the range of 0°C to 110°C.

[0099] Preferably, the diene elastomer polymer has a weight average molecular weight (Mw) higher than 80000 g / mol.

[0100] These polymers or copolymers may be of natural origin or may be obtained by solution polymerization, emulsion polymerization or gas phase polymerization of one or more conjugated diolefins, optionally mixed with up to 60% by weight of at least one comonomer selected from monovinyl arenes and / or polar comonomers.

[0101] The conjugated diolefins generally contain 4 to 12 carbon atoms, preferably 4 to 8 carbon atoms, and may be selected from the group including, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 3-butyl-1,3-octadiene, 2-phenyl-1,3-butadiene and mixtures thereof. 1,3-Butadiene and isoprene are particularly preferred.

[0102] The monovinyl arenes that may optionally be used as comonomers generally contain 8 to 20 carbon atoms, preferably 8 to 12 carbon atoms, and may be selected from, for example, styrene; 1-vinylnaphthalene; 2-vinylnaphthalene; various alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl derivatives of styrene, such as, for example, α-methylstyrene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-p-tolyl-styrene, 4-(4-phenylbutyl)styrene, and mixtures thereof. Styrene is particularly preferred.

[0103] The polar comonomers that may optionally be used are, for example, vinylpyridine, vinylquinoline, acrylic acid and alkyl acrylate esters, nitriles, or mixtures thereof, such as, for example, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile and mixtures thereof.

[0104] Preferably, the diene elastomer polymers that can be used in the present invention can be selected from, for example, cis-1,4-polyisoprene (natural or synthetic, preferably natural rubber), 3,4-polyisoprene, polybutadiene (especially polybutadiene with a high content of 1,4-cis), optionally halogenated isoprene / isobutene copolymers, 1,3-butadiene / acrylonitrile copolymers, styrene / 1,3-butadiene copolymers, styrene / isoprene / 1,3-butadiene copolymers, styrene / 1,3-butadiene / acrylonitrile copolymers, and mixtures thereof.

[0105] The above-mentioned vulcanizable elastomer compounds may optionally contain one or more elastomer polymers of monoolefins having an olefinic comonomer or a derivative thereof. The monoolefins can be selected from, for example, ethylene and α-olefins generally containing 3 to 12 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and mixtures thereof. The following are preferred: copolymers selected from ethylene and α-olefins, optionally having a diene; isobutene homopolymers or copolymers thereof having a small amount of diene optionally at least partially halogenated. The diene that may be present generally contains 4 to 20 carbon atoms and is preferably selected from 1,3-butadiene, isoprene, 1,4-hexadiene, 1,4-cyclohexadiene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, vinyl norbornene, and mixtures thereof. Among them, the following are particularly preferred: ethylene / propylene (EPR) copolymers or ethylene / propylene / diene (EPDM) copolymers; polyisobutene; butyl rubber; halobutyl rubber, especially chlorobutyl or bromobutyl rubber; or mixtures thereof.

[0106] A diene elastomer polymer or an elastomer polymer functionalized by reaction with a suitable terminating agent or coupling agent may be used. In particular, a diene elastomer polymer obtained by anionic polymerization in the presence of an organometallic initiator (in particular, an organolithium initiator) can be functionalized by reacting the residual organometallic groups derived from the initiator with a suitable terminating agent or coupling agent such as, for example, imine, carbodiimide, alkyltin halide, substituted benzophenone, alkoxysilane or aryloxysilane.

[0107] In the process of the present invention for the preparation of a vulcanizable elastomer compound, at least one elastomer polymer may comprise one or more diene elastomer polymers as defined above in a mixture that can be advantageously subjected to a chewing step (step 1-0) for good blending.

[0108] In the process of the present invention, the amount of at least one elastomer polymer or a mixture of two or more elastomer polymers used as defined above amounts to a total of 100 phr.

[0109] In the process of the present invention, at least one vulcanizing agent is preferably selected from sulfur or, as an alternative, sulfur-containing molecules (sulfur donors) such as, for example, caprolactam disulfide (CLD), bis(trialkoxysilyl)propyl] polysulfide, dithiophosphate, phosphoryl polysulfide (SDT) and mixtures thereof.

[0110] Preferably, the vulcanizing agent is sulfur preferably selected from soluble sulfur (crystalline sulfur), insoluble sulfur (polymeric sulfur), (iii) oil-dispersed sulfur and mixtures thereof.

[0111] Commercially available examples of suitable vulcanizing agents are 65% sulfur known under the trade name Rhenogran® of Lanxess, 67% sulfur known under the trade name Crystex OT33 of Eastman, 95% sulfur known under the trade name Schwefel KC of Solvay, and orthorhombic sulfur known under the trade name Sulphur (1% oil and 0.3% silica) of Zolfindustria.

[0112] The vulcanizing agent may generally be present in the vulcanizable elastomer compound in a total amount of 0.1 to 15 phr, preferably 0.5 to 10 phr, and even more preferably 1 to 7 phr.

[0113] The elastomer compound of the present invention may contain one or more vulcanizing agents as defined above in a mixture.

[0114] In the method of the present invention, the vulcanizing agent is preferably used together with adjuvants such as vulcanization accelerators and / or retarders known to those skilled in the art.

[0115] In the method of the present invention, the vulcanization accelerator is preferably selected from dithiocarbamates, guanidines, thioureas, thiazoles, sulfenamides, sulfenimides, thiurams, amines, xanthates, and mixtures thereof.

[0116] Preferably, the accelerator is selected from N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), N-tert-butyl-2-benzothiazole-sulfenamide (TBBS), and mixtures thereof.

[0117] A commercially available example of a suitable accelerator is N-cyclohexyl-2-benzothiazole-sulfenamide Vulkacit® (CBS or CZ) sold by Lanxess.

[0118] The accelerator may generally be present in the vulcanizable elastomer compound in a total amount in the range of 0.05 phr to 10 phr, preferably 0.1 phr to 5 phr.

[0119] The elastomer compound of the present invention may contain, in a mixture, one or more accelerators as defined above.

[0120] In the method of the present invention, the vulcanization retarder may be selected from, for example, urea, phthalic anhydride, N-nitrosodiphenylamine N-cyclohexylthiophthalimide (CTP or PVI), and mixtures thereof.

[0121] A commercially available example of a suitable retarder is N-cyclohexylthiophthalimide VULKALENT® G from Lanxess.

[0122] The retarder may generally be present in the vulcanizable elastomer compound in an amount in the range of 0.05 phr to 2 phr.

[0123] The elastomer compound of the present invention may contain, in a mixture, one or more retarders as defined above.

[0124] Preferably, in the method of the present invention, preferably in the mixing step (1), one or more optional additives such as, for example, at least one reinforcing filler, at least one antioxidant, at least one wax, and at least one plasticizer may be fed.

[0125] In the method of the present invention, the reinforcing filler is selected from carbon black, conventional silica, such as, for example, sand precipitated with a strong acid, preferably amorphous, hydrotalcite, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicate, kaolin, silicate fiber, and mixtures thereof.

[0126] Preferably, the further reinforcing filler is selected from carbon black, conventional silica, silicate fiber, and mixtures thereof, and preferably it is silica.

[0127] Carbon black is of a standard grade for tires or 20 m 2Above / g, more preferably 50 m 2 It can be selected from those having a surface area (measured according to ASTM D6556-16 standard) greater than / g.

[0128] A commercially available example of a suitable reinforcing filler is Zeosil® 1165MP silica manufactured by Solvay Rhodia.

[0129] Commercially available examples of carbon black are N375 or N234 sold by Birla Group (India) or Cabot Corporation.

[0130] The reinforcing filler may generally be present in the vulcanizable elastomer compound in an amount in the range between 0 phr and 120 phr, preferably between 3 phr and 80 phr.

[0131] In one embodiment, the reinforcing filler may be absent, and in this case, the reinforcing function is performed by the compound of formula (II) according to the present invention.

[0132] For some applications, the elastomer compound prepared according to the method of the present invention may contain at least 1 phr, more preferably at least 2 phr, more preferably at least 3 or 4 phr of carbon black, which advantageously protects the elastomer from aging caused by the action of ultraviolet radiation.

[0133] The elastomer compound of the present invention may contain, as a mixture, one or more reinforcing fillers as defined above.

[0134] In the method of the present invention, as antioxidants, phenylenediamine, diphenylamine, dihydroquinoline, phenol, benzimidazole, hydroquinone and their derivatives may be used, optionally as a mixture.

[0135] In the method of the present invention, 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), N,N'-ditoly-p-phenylenediamine (DTPD), N,N'-di-beta-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, etc. and mixtures thereof, and preferably, it is N-(1,3-dimethyl-butyl)-N'-phenyl-p-phenylenediamine (6PPD).

[0136] A commercially available example of a suitable antioxidant is 6PPD from Solutia / Eastman.

[0137] The antioxidant may be present in the vulcanizable elastomer compound in a total amount generally in the range of 0 phr to 20 phr, preferably between 0.5 phr and 10 phr.

[0138] In the method of the present invention, the wax may be, for example, a petroleum wax or a mixture of paraffins.

[0139] Commercially available examples of suitable waxes are the N-paraffin mixture from Repsol and Antilux® 654 microcrystalline wax from Rhein Chemie.

[0140] The wax may be present in the vulcanizable elastomer compound in a total amount generally in the range of 0 phr to 20 phr, preferably between 0.5 phr and 5 phr.

[0141] In the method of the present invention, in order to further improve processability, the elastomer compound may be admixed with at least one plasticizer generally selected from mineral oils, vegetable oils, synthetic oils, polymers having a low molecular weight, and mixtures thereof, for example, aromatic oils, naphthenic oils, phthalates, soybean oil, and mixtures thereof. The amount of the plasticizer is generally in the range of 0 phr to 70 phr, preferably 5 phr to 30 phr. Preferably, the plasticizer, if present, is added in the polymer chewing step.

[0142] A fourth aspect of the present invention is represented by a vulcanizable elastomer compound obtained according to the method of the third aspect of the present invention.

[0143] In the elastomer compound according to the present invention, iron is present in ionic form as Fe bonded by a coordination bond to form a compound represented by formula (II) of the present invention, but not in the form of metallic iron (Fe). 3+ and does not exist in the form of metallic iron (Fe).

[0144] The amount of iron in the compound can be determined, for example, by ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) spectrometry as described in the experimental part.

[0145] The vulcanizable elastomer compound of the present invention can be incorporated into one or more components of a tire.

[0146] Thanks to the method of the present invention, it is possible to eliminate zinc incorporated into the compound, with important environmental benefits, without further deteriorating or improving their performance compared to equivalent conventional compounds.

[0147] According to a fifth aspect of the present invention, the elastomer compound of the present invention is applied to tire components such as treads, underlayers, abrasion-resistant extension elements, sidewalls, sidewall inserts, mini sidewalls, underliners, rubber layers, bead fillers, and sheets, more preferably in the tread, in the underlayer, in the sidewall and underliner.

[0148] Preferably, the tire component according to the present invention is composed of a vulcanizable compound (green component) according to the present invention or a vulcanized compound (vulcanized component) obtained by vulcanizing the same.

[0149] A sixth aspect of the present invention is a vehicle wheel tire including at least one of the components shown above.

[0150] Preferably, the vehicle wheel tire according to the present invention includes at least one tire component composed of a vulcanizable elastomer compound (green component) according to the second aspect of the present invention or a vulcanized elastomer compound obtained by vulcanizing the same.

[0151] In one embodiment, the vehicle tire according to the present invention - includes at least a carcass structure including a carcass ply having opposing lateral edges each connected to a respective bead structure, - optionally, a pair of sidewalls each applied to an axially outer position of a lateral surface of the carcass structure, - optionally, a belt structure applied to a radially outer position relative to the carcass structure, - a tread band applied to a radially outer position relative to the carcass structure or, if present, to the belt structure, - optionally, a layer of an elastomeric material called an underlayer applied to a radially inner position relative to the tread band and includes at least At least one component selected from the group consisting of the sidewall pair, the underlayer, and the tread band contains or preferably consists of an elastomer compound according to the present invention.

[0152] Embodiments according to the present invention relate to high-performance vehicle (HP, SUV, and UHP) tires in which at least one component preferably selected from the underlayer, sidewall, and tread band contains or preferably consists of an elastomer compound according to the present invention.

[0153] Embodiments according to the present invention relate to large vehicle tires in which at least one component preferably selected from the underlayer, sidewall, and tread band contains or preferably consists of an elastomer compound according to the present invention.

[0154] The tire according to the present invention can be a tire for a two-, three-, or four-wheeled vehicle.

[0155] In one embodiment, the tire according to the present invention is a tire for a bicycle wheel.

[0156] A tire for a bicycle wheel typically includes a carcass structure wound around a bead core pair at the bead and a tread band disposed at a radially outer position relative to the carcass structure.

[0157] The carcass structure is intended to withstand inflation pressure and support the weight of the bicycle and the person riding the bicycle. The carcass structure includes one or more carcass plies, each including a plurality of suitably oriented reinforcing cords. In the case of some carcass plies, they are inclined relative to each other to form a cross structure.

[0158] The bead core has the role of ensuring that the tire is fixed to the wheel rim.

[0159] An air chamber into which pressurized air is introduced may be provided at a radially inner position of the carcass structure.

[0160] The tire according to the present invention can be a summer tire, a winter tire, or an all-season tire.

[0161] The tire according to the present invention - constructing the components of the green tire on at least one forming drum - shaping, moulding, and vulcanizing the tire including wherein constructing at least one of the components of the green tire - manufacturing at least one green component comprising, or preferably consisting of, the vulcanizable elastomer compound of the present invention can be manufactured according to a process including.

[0162] In particular, FIG. 1 shows a radial half-section of a vehicle wheel tire comprising a vulcanized elastomer compound prepared by vulcanization of an elastomer compound prepared according to the method of the present invention.

[0163] In FIG. 1, “a” indicates the axial direction, “X” indicates the radial direction, and in particular X-X indicates the contour of the equatorial plane. For simplicity, FIG. 1 shows only a part of the tire, and the remaining parts not shown are identical and are arranged symmetrically with respect to the equatorial plane “X-X”.

[0164] The four-wheel vehicle tire 100 includes at least one carcass structure including at least one carcass layer 101, and the carcass layer 101 has respective opposing end flaps engaged with respective annular fixed structures 102 called bead cores, which are optionally associated with bead fillers 104.

[0165] The carcass layer 101 is optionally made of an elastomer compound.

[0166] The region of the tire including the bead core 102 and the filler 104 forms a bead structure 103 intended to secure the tire to a corresponding mounting rim (not shown).

[0167] The carcass structure is typically of the radial type, i.e., the reinforcing elements of at least one carcass layer 101 are arranged substantially perpendicular to the equatorial plane of the tire on a plane including the axis of rotation of the tire. The reinforcing elements generally consist of textile cords such as rayon, nylon, polyester (e.g., polyethylene naphthalate, PEN), etc. Each bead structure is associated with the carcass structure by folding back the opposing lateral edges of at least one carcass layer 101 around the annular fixing structure 102 so as to form a so-called carcass flap 101a, as shown in FIG. 1.

[0168] In one embodiment, the connection between the carcass structure and the bead structure can be provided by a second carcass layer (not shown in FIG. 1) applied at an axially outer position with respect to the first carcass layer.

[0169] A wear-resistant strip 105, optionally made of an elastomeric compound, is disposed at an outer position of each bead structure 103.

[0170] The carcass structure is associated with a belt structure 106 including one or more belt layers 106a, 106b radially superimposed with respect to each other and with respect to the carcass layer, and each belt layer typically has textile and / or metal reinforcing cords incorporated within a layer of vulcanized elastomeric compound.

[0171] Such reinforcing cords may have a cross-orientation with respect to the direction of circumferential development of the tire 100. The "circumferential" direction generally means the direction facing the direction of rotation of the tire.

[0172] At least one zero-degree reinforcing layer 106c, which is generally known as a "0° belt", may be applied at the outermost position in the radial direction with respect to the belt layers 106a, 106b. The zero-degree reinforcing layer 106c generally incorporates a plurality of elongation reinforcing elements oriented substantially in the circumferential direction, typically metal or textile cords. Therefore, the elongation reinforcing elements form an angle of several degrees (such as an angle between about 0° and 6°) with respect to the direction parallel to the equatorial plane of the tire.

[0173] The tread band 109 of the vulcanized elastomer compound is applied at the outermost position in the radial direction of the belt structure 106.

[0174] Furthermore, each sidewall 108 of the vulcanized elastomer compound is applied at an axially outer position on the lateral surface of the carcass structure, and each sidewall 108 extends respectively from one of the lateral edges of the tread 109 in each bead structure 103.

[0175] At the outermost position in the radial direction, the tread band 109 has a rolling surface 109a intended to contact the ground. Circumferential grooves connected by transverse notches (not shown in FIG. 1) are generally formed on this surface 109a so as to define a plurality of blocks of various shapes and sizes distributed across the rolling surface 109a, and are shown flat in FIG. 1 for simplicity.

[0176] An underlayer 111 of the vulcanized elastomer compound may be disposed between the belt structure 106 and the tread band 109.

[0177] A strip made of an elastomeric compound 110, which is generally known as a "mini sidewall" of a vulcanized elastomeric compound, can be optionally provided in the connection area between the sidewall 108 and the tread band 109. This mini sidewall is generally obtained by co-extrusion with the tread band 109 and enables improvement of the mechanical interaction between the tread band 109 and the sidewall 108. Preferably, the end of the sidewall 108 directly covers the lateral edge of the tread band 109.

[0178] In the case of a tubeless tire, a rubber layer 112, which is generally known as a "liner" and provides the impermeability required for the inflation air of the tire, can also be provided at a radially inner position with respect to the carcass layer 101.

[0179] The rigidity of the tire sidewall 108 can be improved by providing a reinforcing layer 120, which is generally known as a "flipper", or an additional strip-like insert in the bead structure 103.

[0180] The flipper 120 is a reinforcing layer that is wound around each bead core 102 and bead filler 104 so as to at least partially surround them, and the reinforcing layer is disposed between at least one carcass layer 101 and the bead structure 103. Usually, the flipper is in contact with the at least one carcass layer 101 and the bead structure 103.

[0181] The flipper 120 typically includes a plurality of textile cords incorporated within a layer of vulcanized elastomeric compound.

[0182] The bead structure 103 of the tire may include a further protective layer or protective strip, which is generally known by the term "chafer" 121 and has the function of increasing the rigidity and integrity of the bead structure 103.

[0183] The chafer 121 typically includes a plurality of cords incorporated within a rubber layer of a vulcanized elastomer compound. Such cords are generally made of a textile material (such as aramid or rayon) or a metallic material (such as a steel cord).

[0184] A layer or sheet of the elastomer compound can be disposed between the belt structure and the carcass structure. The layer can have a uniform thickness. Alternatively, the layer can have a variable thickness axially. For example, the layer can have a greater thickness near its axial outer edge compared to the central (crown) region.

[0185] Advantageously, the layer or sheet can extend up to a surface that substantially corresponds to the extension plane of the belt structure.

[0186] In a preferred embodiment, a layer or sheet of the elastomer compound as described above can be placed between the belt structure and the tread band, and the additional layer or sheet preferably extends up to a surface that substantially corresponds to the extension plane of the belt structure.

[0187] The elastomer compound according to the present invention can advantageously be incorporated into one or more of the tire components selected from a belt structure, a carcass structure, a tread band, an underlayer, a sidewall, a mini sidewall, a sidewall insert, a bead, a flipper, a chafer, a sheet, and a wear-resistant strip, and preferably can be incorporated into at least the sidewall and / or the underlayer.

[0188] According to an embodiment not shown, the tire can be a tire for a two-wheeled vehicle, which typically has a straight portion with a high tread camber.

[0189] According to an embodiment not shown, the tire can be a tire for a bicycle wheel.

[0190] According to an embodiment not shown, the tire can be a tire for wheels of large transport vehicles such as trucks, buses, trailers, vans, etc., generally a tire for vehicles to which the tire is subjected to high loads. Preferably, such a tire is adapted to be mounted on a wheel rim having a diameter of 17.5 inches or more for wheels of a steer or trailer.

[0191] A description of some preparation examples and comparative examples according to the present invention, which are described only by way of illustration and not limitation of the scope of the present invention, is set forth below.

[0192] Experimental part Analysis method White filler functionalization The functionalization of the white filler was verified by ATR-FTIR, TGA, CHNS, and BET analysis.

[0193] ATR-FTIR analysis was performed on a Perkin Elmer Spectrum 100 instrument (spectrum with a resolution of 4 cm -1 , region of 650 - 400 cm -1 , 32 scans).

[0194] Thermogravimetric analysis (TGA) was performed using a TGA / DCS1 STARe system (Mettler Toledo) instrument with a constant gas flow (50 mL per minute). The method used involves applying a heating ramp of 10 °C per minute starting from an initial temperature of 30 °C to a final temperature of up to 1000 °C. Two 15-minute isotherms were also added at 150 °C and 1000 °C. The measurements were carried out in an alumina crucible with a volume of 75 μL.

[0195] CHNS analysis was performed on an Elementar VarioMICRO analyzer with a CHNS instrument configuration. The measurement uncertainty is reported to be 0.1%. The measured values were normalized against a sulfanilamide standard. The combustion column was at a temperature of 1150 °C, while the reduction column was at 850 °C.

[0196] The BET analysis was carried out using a Micromeritics TristarII porosity and surface area analyzer.

[0197] Determination of iron content The iron content can be measured by ICP-AES spectroscopy (inductively coupled plasma-atomic emission spectroscopy) using an ICP simultaneous plasma spectrometer (TJA IRIS II model; excitation source: high-frequency generator with a frequency of 27.12 MHz and a variable output power up to 1750 W).

[0198] MDR rheometric analysis (according to ISO 6502): An Alpha Technologies MDR2000 type rheometer was used. The test was carried out at 170 °C for 10 minutes at a vibration frequency of 1.66 Hz (100 vibrations per minute) and a vibration amplitude of ±0.5 ° to measure the time required to achieve an increase in two rheometric units (TS2), the maximum torque value (MH), and the time required to achieve 30% (T30) and 100% (T100) of the maximum torque value (MH), respectively.

[0199] Properties of vulcanized materials The elastomer material prepared in the previous example was vulcanized to obtain a specimen, and analytical characterization and evaluation of dynamic mechanical properties were performed on this.

[0200] Unless otherwise instructed, vulcanization was carried out in a mold in a hydraulic press at 170 °C and a pressure of 200 bar for about 10 minutes.

[0201] Static modulus of elasticity: The static mechanical properties were measured at 23 °C according to the ISO 37:2005 standard. In particular, the tensile stress at various elongation levels (10%, 50%, 100%, and 300%, named CA0.1, CA0.5, CA1, and CA3 in order) was measured for samples of the vulcanized elastomer composition.

[0202] Dynamic coefficient: The dynamic mechanical properties were measured in compression and tension using an Instron® dynamic device and the following method. A sample of a vulcanized elastomeric cylindrical composition (length = 25 mm; diameter = 18 mm) preloaded with a longitudinal deformation of up to 25% of the initial length during compression and maintained at a predetermined temperature (10 °C, 23 °C or 100 °C) during the test was subjected to a dynamic sinusoidal stress with an amplitude of ±3.5% with respect to the preloaded length at frequencies of 1 Hz, 10 Hz and 100 Hz.

[0203] The dynamic mechanical properties are expressed in terms of the dynamic elastic modulus (E’), the viscous dynamic modulus (E’’) and the dielectric tangent (loss factor). The dielectric tangent value was calculated as the ratio between the viscous dynamic modulus (module) (E’’) and the dynamic elastic modulus (E’).

[0204] G (shear) dynamic coefficient: They were measured using a Monsanto R.P.A. rheometer 2000 according to the following method: punching out the vulcanizable elastomeric composition of the sample in the instrument “RPA” (for 10 minutes at 170 °C) and vulcanizing it to obtain a cylindrical test specimen with a weight in the range of 4.5 - 5.5 g. The vulcanized sample was subjected to a dynamic measurement of the shear elastic modulus (G’) at 70 °C, 10 Hz frequency, 0.1% and 10% strain. The dynamic elastic properties were expressed in terms of the dynamic shear elastic modulus (G’), the viscous shear modulus (G’’) and the dielectric tangent (loss factor) at 3% and 9% strain. The dielectric tangent value was calculated as the ratio between the viscous shear modulus (G’’) and the dynamic shear elastic modulus (E’).

[0205] Example 1 Preparation of functionalized silica Materials used · Rhodia Zeosil® MP1165 precipitated silica produced by Rhodia (specific surface area BET 160 m 2 / g), · Coupling agent (APTES) produced by Sigma Aldrich: (3-aminopropyl)triethoxysilane H2N(CH2)3Si(OC2H5)3 (99%), · Ferric sulfate (Fe2(SO4)3*xH2O) produced by Sigma Aldrich, · Toluene (99%) produced by Alfa Aesar, · Absolute ethanol EtOH (99.9%) produced by Scharlau.

[0206] The preparation consists of a two-step process in which silica is first functionalized with a coupling agent and, after recovery, the anhydrous powder is reacted with an iron precursor (hydrated ferric sulfate) to bind ionic iron (Fe 3+ ) via the formation of a chelate with the ligand GC.

[0207] The first step 1 g of SiO2 powder was dispersed in 25 ml of toluene in a 50 ml flask with stirring at 120 °C for 10 minutes. Then, 0.394 ml of (3-aminopropyl)triethoxysilane (APTES), calculated in such a way as to have a molar ratio equal to 1:2 between APTES and the number of hydroxyl groups on the silica surface, was added to the dispersion and the reaction mixture was maintained at 120 °C for 24 hours with stirring (reflux conditions). After cooling, the reaction product (SiO2-APTES) was recovered by vacuum filtration, washed twice with fresh toluene and dried overnight in an oven at 80 °C.

[0208] The characterization of the above preparation and of the functionalized silica (SiO2-APTES) obtained in the first step by ATR-FTIR, TGA and CHNS analysis is similar to that described in WO2020 / 110023 in the name of the applicant and in S. Mostoni et al., “Design of a Zn Single-Site Curing Activator for a More Sustainable Sulfur Cross-Link Formation in Rubber” Ind. Eng. Chem. Res. 2021, 60, 10180-10192.

[0209] TGA and CHNS analysis made it possible to confirm the functionalization of silica after reaction with APTES, and the results are summarized in Table A below.

[0210] [Table 1]

[0211] Second step 1 g of the functionalized silica (SiO2-APTES) obtained in the first step was dispersed in 50 mL of ethanol with stirring at 100 °C for 20 minutes so as to obtain a homogeneous suspension. Then, an appropriate amount of iron precursor (Fe2(SO4)3·xH2O) was added. The amounts of the iron precursor used were calculated considering molar ratios Fe / APTES (n Fe(precursor) / n APTES ) equal to 1:20, 1:10, 1:2, 1:1 and 2:1, assuming that iron ions cannot bind directly to the surface of silica nanoparticles.

[0212] The reaction was carried out for 2 hours, and after cooling, the reaction product (SiO2-APTES-Fe) was separated by filtration under vacuum, washed twice with fresh ethanol to remove unreacted salts, and dried at 80 °C for 12 hours.

[0213] In this way, SiO2-APTES x -Fe Y[wherein the subscripts Y and X denote the nominal molar ratio Fe / APTES (n Fe(precursor) / n APTES ) used during the synthesis reaction, respectively], five different catalysts named as such are prepared.

[0214] Characterization of the obtained materials ICP-OES-Inductively coupled plasma optical emission spectrometry This characterization technique enables the determination of the amount of Fe 3+ ions immobilized on silica nanoparticles by utilizing the amine ligand (APTES), and enables the estimation of the type of metal-ligand coordination by leveraging the analysis of materials prepared with different irons starting from metal precursors with different contents.

[0215] ICP analysis was carried out using a Perkin Elmer Optima 7000DV spectrometer (software-controlled WinLab32) connected to a microwave digestion system. For each analysis, 0.2 g of the powder material was finely ground and then the sample was prepared by dissolving it in an acid solution composed of 4 mL of HNO3, 3 mL of HCl, and 1 mL of HF. Subsequently, the sample was processed in the digestion system in the following steps: i) 160 °C for 8 minutes, ii) 200 °C for 5 minutes, iii) 200 °C for 20 minutes. The solution was diluted with 12 mL of MilliQ water, and finally 15 mL of this solution was further diluted 1:100 and introduced into the ICP instrument for analysis. The vaporized sample was transported inside the plasma source by a constant flow of argon at 20 L / min.

[0216] Table B below indicates the number of Fe 3+ ions and APTES molecules determined by ICP and TGA measurements for each of the five prepared catalysts.

[0217] [Table 2]

[0218] Fe coordinated by APTES molecules 3+The amount of ions increased as the amount of the metal precursor used in the synthesis increased. However, SiO2-APTES x -Fe Y The maximum n Fe / n APTES molar ratio obtained in the material is always about 1 even in the presence of excess iron, while the maximum n Fe / n APTES = 0.5, and the calculated molar ratio (n Fe / n APTES ) and the nominal molar ratio (n Fe(precursor) / n APTES ) are almost identical (Figure 3). This tendency suggests that in SiO2-APTES x -Fe Y , even if double coordination cannot be excluded when the amount of iron used in the synthesis is incomplete compared to that of APTES, the iron metal center is preferentially coordinated by the APTES molecules fixed on the silica.

[0219] TEM - Transmission Electron Microscopy Analysis The morphology of the activator was studied by TEM and TEM-EDX analysis, and the latter of these enables investigation of the elemental composition of the material in particular.

[0220] The analysis was carried out using a JEOL Jem-2100plus TEM transmission electron microscope operating at 200 kV with a Gatan Rio (trademark) complementary metal oxide semiconductor (CMOS) camera of 8 megapixels. The powder sample to be analyzed was supported by a specific copper grid for TEM analysis.

[0221] From the analysis performed, a substantially homogeneous distribution of iron was observed on the surface of the silica particles, accompanied by the presence of sulfur ions that may be derived from the residual sulfate groups of the metal precursor, which almost certainly remains within the coordination sphere of the metal but does not affect its reactivity.

[0222] Example 2 Preparation of Elastomer Compounds Table 1 below shows the formulations of a reference compound (RIF1) containing silica and zinc oxide, a comparative compound (CON1) containing silica and ferric sulfate itself, and a compound (INV1) according to the invention containing a vulcanization activator SiO2-APTES2-Fe1 with a molar ratio Fe / APTES 1:2 prepared as described in Example 1.

[0223] The reference compound (RIF1) is a conventional compound commonly used in the production of tire parts, and the comparative compound (CON1) is a compound prepared to demonstrate the inactivity of common iron salts compared to the vulcanization activator used in the compound (INV1) of the present invention.

[0224] [Table 3]

[0225] All components except sulfur and accelerator (CBS) were mixed together in an internal mixer (model Pomini PL1.6) for about 5 minutes (first step). As soon as the temperature reached 145 ± 5 °C, the elastomer compound was taken out. Then, sulfur and accelerator (CBS) were added and the mixing was carried out in an open roll mixer (second step).

[0226] Specimens were prepared using the compounds in Table 1 and MDR rheometric measurements and the (shear) dynamic coefficient G were performed on them as described above.

[0227] The results are summarized in Table 2 below.

[0228] [Table 4]

[0229] The results show that the compound (INV1) of the present invention containing the vulcanization activator SiO2-APTES2-Fe1 of the present invention has Fe 3+It has been demonstrated to have high vulcanization efficiency not only compared to the comparative compound (CON1) containing the general salts thereof, but also compared to the reference compounds containing conventional zinc-based vulcanization activators.

[0230] The high G’(3%) and G’(9%) values indicated the high elasticity of the compound, predicting high tire response and thus better performance during its use. The low values of the dielectric tangent (3%) and (9%) conversely indicated low hysteresis and thus low rolling resistance values of the tire.

[0231] Fe2(SO4)3 alone could not activate the vulcanization process, i.e., without forming a metal complex with the organic ligand immobilized on the silica surface, because low torque values were obtained, resulting in insufficient mechanical properties.

[0232] The results obtained led to the development of a heterogeneous catalyst, confirming that the vulcanization activator SiO2-APTES2-Fe1 had a decisive effect on vulcanization efficiency and its chemical nature could act as a dual-functional filler that could modulate the final properties of the material.

[0233] Figure 2 shows a cartograph regarding the vulcanization curves of the elastomer compounds RIF1, CON1, and INV1.

[0234] By using the compound of the present invention as a vulcanization activator, a complete and homogeneous dispersion of iron, which has an undeniable advantage in the subsequent vulcanization reaction, was obtained. Furthermore, the absence of zinc made these mixtures sustainable from an environmental perspective by avoiding the release of zinc, which is toxic to aquatic organisms, into the environment.

[0235] Example 3 Preparation of the elastomer compound Table 3 below shows the formulations of reference compounds (RIF2 and RIF3) containing silica and variable amounts of zinc oxide, and of a compound according to the invention (INV2) containing the vulcanization activator SiO2-APTES2-Fe1 with a molar ratio Fe / APTES of 1:2 prepared as described in Example 1 and without addition of a vulcanization accelerator (CBS).

[0236]

Table 5

[0237] All components except sulfur and the accelerator (CBS) were mixed together in an internal mixer (model Pomini PL1.6) for about 5 minutes (first step). As soon as the temperature reached 145 ± 5 °C, the elastomer compound was taken out. If intended, sulfur and the accelerator (CBS) were then added and the mixing was carried out in an open roll mixer (second step).

[0238] Using the compounds of Table 3, specimens were prepared and for these, MDR rheometric measurements and the static elastic moduli CA0.1, CA0.5 and CA1 were carried out as described above.

[0239] The results are summarized in Table 4 below.

[0240]

Table 6

[0241] The maximum torque results (MH) demonstrated the excellent vulcanization efficiency of the compound of the invention (INV2) containing the vulcanization activator SiO2-APTES2-Fe1 of the invention, compared to the reference compounds (RIF2 and RIF3) containing different amounts of conventional zinc-based vulcanization activators even in the absence of an accelerator.

[0242] The compound (INV2) of the present invention indicated good elasticity of the compound and showed higher values of Ca0.1, Ca0.5, and Ca1 than the reference compounds (RIF2 and RIF3), predicting good response characteristics and handling of the tire under service conditions as well as its better durability.

[0243] Example 4 Preparation of Elastomer Compounds Table 5 below shows the formulations of the reference compounds (RIF4 and RIF5) containing silica and variable amounts of zinc oxide, as well as the compound (INV3) according to the present invention containing the vulcanization activator SiO2-APTES2-Fe1 with a molar ratio of Fe / APTES 1:2 prepared as described in Example 1.

[0244] In this test, all compounds were added without a vulcanization accelerator (CBS).

[0245] [Table 7]

[0246] All components except sulfur were mixed together in an internal mixer (model Pomini PL1.6) for about 5 minutes (first step). As soon as the temperature reached 145 ± 5 °C, the elastomer compound was taken out. Then, sulfur was added and the mixing was carried out in an open roll mixer (second step).

[0247] Using the compounds in Table 5, specimens were prepared and subjected to MDR rheometric measurements and static elastic moduli CA0.1, CA0.5, CA1, and CA3 as described above.

[0248] The results are summarized in Table 6 below.

[0249] [Table 8]

[0250] The values of the maximum torque (MH) and the static elastic modulus (Ca0.1, Ca0.5, Ca1, and Ca3) of the compound (INV3) of the present invention showed a significant increase in characteristic values as demonstrated by the values of TS2 and T30, as well as how the vulcanization activator SiO2-APTES2-Fe1 of the present invention played a significant role in both mechanical properties and vulcanization kinetics.

[0251] The data in Table 6 confirmed that SiO2-APTES2-Fe1 is a complete and efficient vulcanization activator even in the absence of a vulcanization accelerator.

[0252] Example 5 Preparation of Elastomer Compounds The following Table 7 shows the formulations of reference compounds (RIF6 and RIF7) containing silica and zinc oxide, and of the compound (INV4) according to the present invention containing the vulcanization activator SiO2-APTES2-Fe1 with a 1:2 molar ratio of Fe / APTES prepared as described in Example 1 and without adding a vulcanization accelerator (CBS).

[0253] [Table 9]

[0254] All components except sulfur and the accelerator (CBS) were mixed together in an internal mixer (model Pomini PL1.6) for about 5 minutes (first step). As soon as the temperature reached 145 ± 5 °C, the elastomer compound was taken out. If intended, sulfur and the accelerator (CBS) were then added and the mixing was carried out in an open roll mixer (second step).

[0255] Using the compounds in Table 7, specimens were prepared and for them, MDR rheometric measurements, the (shear) dynamic coefficient G and the static elastic modulus CA0.1 were carried out as described above.

[0256] The results are summarized in Table 8 below.

[0257]

Table 10

[0258] The results in Table 8 demonstrated that the vulcanization activator SiO2-APTES2-Fe1 of the present invention showed high vulcanization efficiency even in the absence of an accelerator and even for compounds containing different polymers.

[0259] The values Ca0.1, G’, and MH indicating the vulcanization of the material were all higher in the compound (INV4) of the present invention than in the reference compounds (RIF6 and RIF7).

Claims

1. Formula (II): WF-O-ROS-GC-Fe (II) [wherein, WF represents a white filler, O represents one or more oxygen bridge bonds, ROS represents an organosilane residue, GC represents one or more coordination groups that form a chelate with ionic iron, and Fe represents ionic iron coordinated with the coordination group (Fe ３＋ ).] A compound represented by.

2. A method for preparing the compound of formula (II) according to Claim 1, comprising: - A step of preparing a white filler (WF); - The following formula (I): GR-ROS-GC (I) [wherein, GR represents one or more reactive groups capable of forming an oxygen (-O-) bridge with the surface of the white filler, ROS represents an organosilane residue, and GC represents one or more coordinating groups] - A step of preparing a coupling agent having; ・ Prepare an ionic iron precursor (Fe ３＋ ), and - Reacting the white filler (WF) with one or more reactive groups (GR) of the compound of formula (I) so as to form an oxygen (-O-) bridge between the white filler and the organosilane residue (ROS); ・ Reacting one or more coordinating groups (GC) of the compound of formula (I) with an ionic iron precursor (Fe ３＋ ) to form a chelate; - A step of separating the obtained compound of formula (II) WF-O-ROS-GC-Fe A method comprising at least.

3. The compound according to Claim 1 or the method according to Claim 2, wherein the white filler WF is selected from the group consisting of silica and silicates in the form of fibers, films or granules.

4. The compound or method according to Claim 3, wherein the white filler WF is selected from the group consisting of bentonite, nontronite, beidellite, volkonskoite, hectorite, saponite, sauconite, vermiculite, sericite, sepiolite, palygorskite also known as attapulgite, montmorillonite, allophane, etc., and mixtures thereof, optionally modified and / or derivatized by acid treatment.

5. The compound according to Claim 1 or the method according to Claim 2, wherein the coordinating group (GC) is a linear or branched alkyl chain containing one or more heteroatoms inside or at the end of the alkyl chain.

6. wherein the ligand GC is of the formula -C ｎ H ２ｎ -X-C ｍ H ２ｍ -Y or -C ｍ H ２ｍ -Y [wherein equal or different n and m are integers from 1 to 6 (including 1 and 6), X is a group selected from mercapto and amino, and Y is a group selected from mercapto, amino, dithiocarbamate, and carboxyl], the compound or method according to claim 5.

7. The method according to Claim 2, wherein the reactive group GR is an alkoxy group having 1 to 4 carbon atoms.

8. The coupling agent is of general formula (Ia) or (Ib): (R) ３ Si-C ｎ H ２ｎ -X-C ｍ H ２ｍ -Y (Ia) (R) ３ Si-C ｍ H ２ｍ -Y (Ib) [wherein, the same or different R groups 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 the same or different n and m are integers from 1 to 6 (including 1 and 6), X is a group selected from mercapto and amino, and Y is a group selected from mercapto, amino, dithiocarbamate, and carboxyl] The method according to claim 2, represented by

9. The coupling agent is selected from the group consisting of (3-aminopropyl)triethoxysilane (APTES), N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (also known as N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDTMS)), N-(2-aminoethyl)-3-aminopropyl-triethoxysilane, N-(2-aminoethyl)-3-aminopropyl-methyl-dimethoxysilane, 3-aminopropylmethyl-diethoxysilane, 3-ureidopropyl-trimethoxysilane, 3-ureidopropyl-triethoxysilane, N-cyclohexyl(aminomethyl)methyldiethoxysilane, N-cyclohexyl(aminomethyl)triethoxysilane, N-cyclohexyl-3-aminopropyl-trimethoxysilane, 3-(2-aminomethylamino)propyl-triethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxy-silane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminoisobutyl-methyl-dimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-(2-(2-aminoethylamino)ethylamino)propyl-trimethoxysilane, N-(n-butyl)-3-aminopropyl-triethoxysilane, Ν,Ν-diethylaminopropyl-trimethoxysilane, N,N-dimethylaminopropyl-trimethoxysilane, butylaminomethyl-triethoxysilane, N-cyclohexyl(aminomethyl)trimethoxy-silane, 2-aminoethylaminomethyl-triethoxysilane, diethylaminomethyl-triethoxysilane, (3-mercaptopropyl)triethoxysilane, and (3-mercaptopropyl)trimethoxysilane, the method according to claim 2

10. The method according to claim 9, wherein the coupling agent is selected from the group consisting of (3-mercaptopropyl)trimethoxysilane, (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.

11. The ionic iron precursor (Fe ３＋ ), which is selected from the group consisting of ferric oxide (Fe ２ O ３ ), ferric hydroxide (Fe(OH) ３ ), and organic or inorganic salts of Fe ３＋ ), the method according to claim 2.

12. The method according to claim 11, wherein the organic or inorganic salt of iron is selected from the group consisting of ferric nitrate, ferric sulfate, ferric carbonate, ferric chloride, ferric bromide, ferric iodide, ferric fluoride, ferric phosphate, ferric acetate, ferric oxalate, ferric citrate, ferric gluconate, ferric fumarate, and ferric lactate.

13. A method for the preparation of a vulcanizable elastomer compound for a tire, comprising: - A mixing step (1) of at least one elastomeric polymer and at least one additive for an elastomer compound other than a vulcanizing agent to obtain an unvulcanized elastomer compound; - A mixing step (2) of the unvulcanized elastomer compound and at least one vulcanizing agent to obtain a vulcanizable elastomer compound; - A step of taking out the vulcanizable elastomer compound, and at least including: In at least one of the mixing steps (1) and (2), the compound of formula (II) according to claim 1 is added. Method.

14. A vulcanizable elastomer compound obtained according to the method of claim 13.

15. A tire component comprising the vulcanizable compound according to claim 14 or a vulcanized compound obtained by vulcanizing the same.

16. A tire for a vehicle wheel comprising the component according to claim 15.

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