Method for preparing tire compounds and tires containing them - Patents.com

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 elastomeric tire compounds that can be effectively vulcanized without the introduction of zinc, characterized by the incorporation of specific modified fillers capable of activating vulcanization. [Background technology]

[0002] In the tire industry, vulcanization is a process commonly used to improve the mechanical properties of natural rubber or unsaturated polymers; it is a process that affects the hardness, elasticity, hysteresis of the material at different temperatures and, consequently, the behavior of the wet tire and its friction and wear in use.

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

[0004] In general, it is desirable to use these additives to increase the degree and uniformity of crosslinking while decreasing 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 the various activators, zinc oxide (ZnO) is considered the most efficient and is still used today in many vulcanization processes. This activator is used in combination with a weak organic acid (e.g., stearic acid) to promote its activity in the rubber.

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

[0008] Since zinc can contaminate 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 compounds and thereby reduce the amount of zinc dispersed into the environment by normal tire wear.

[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-aminopropyltriethoxysilane (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 WO 2020 / 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] Subsequently, research was conducted into 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 vulcanization—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 and magnesium oxides in the vulcanization reaction showed that when calcium oxide is used as the activator, the kinetics are slower and a lower degree of crosslinking is achieved. If, instead, magnesium oxide is used instead of ZnO, the accelerator reacts with better kinetics in the first step of the vulcanization reaction, but even in this case, a lower crosslink density is reached than that obtained with zinc oxide. In this case, zinc oxide remains the best activator, resulting in a high degree of crosslinking. (Roy, K.; Alam, MN; Mandal, SK; Debnath, SC 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, especially as iron oxide, in elastomer compounds to impart some specific properties to the final material, such as magnetic, electrical or conductive properties, or to influence the cross-linking 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 effect of 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 crosslinking process of chloroprene-butadiene rubber compounds (CR / BR) and observed that the resulting CR / BR / Fe2O3 vulcanizates were characterized by good mechanical properties, higher curing speed, and high fire resistance.

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

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

[0018] The applicant has undertaken research to further improve the effectiveness of activating fillers in the production of compounds for tires, with the aim of eliminating zinc incorporated in the compounds, without worsening or even improving their performance compared to comparable conventional compounds, with important environmental benefits.

[0019] Surprisingly, the Applicant has discovered that ionic iron Fe 3+can be coupled to particles of white filler, e.g., silica nanoparticles, via a coupling agent that contains reactive groups capable of bonding with the surface of the white filler, in particular those capable of forming oxygen bridges, and coordinating groups capable of chelating iron in ionic form.

[0020] Thus, the coupling agent has the following formula (I): GR-ROS-GC (I) wherein GR represents one or more reactive groups capable of bonding with 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. This can be diagrammed as follows:

[0021] Moreover, the material produced by the applicant therefore has the following formula (II): WF-O-ROS-GC-Fe (II) [wherein the reactive group GR reacted 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 chelated the ionic iron] This can be diagrammed as follows:

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

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

[0024] Applicant has observed that the use of such materials allows for the use of lower mixing temperatures since the use of silanes is not required to maximize the integrity of the material and the cost of preparing the elastomeric compound subjected to vulcanization.

[0025] Moreover, the applicant has observed that such materials allow for faster vulcanization times and better mechanical properties of the resulting vulcanized material.

[0026] A further advantage observed by the applicant consists in 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 present invention is a compound of formula (II): WF-O-ROS-GC-Fe (II) A compound represented by [Wherein, WF represents a white filler, O represents one or more oxygen bridge bonds, ROS represents an organosilane residue, GC represents one or more coordinating groups that form a chelate with ionic iron, and Fe represents ionic iron (Fe) coordinated with the coordinating groups. 3+ ) represents is.

[0028] A second aspect of the present invention is a process for the preparation of a compound represented by formula (II) of the first aspect of the present invention, comprising: providing a white filler (WF); Formula (I): GR-ROS-GC (I) wherein GR represents one or more reactive groups capable of forming oxygen (—O—) bridges with the surface of the white filler, ROS represents an organosilane residue, and GC represents one or more coordinating groups. providing a coupling agent having Ionic iron precursor (Fe 3+ ) preparing a reacting a white filler (WF) with one or more reactive groups (GR) of said compound of formula (I) to form oxygen (—O—) bridges between said white filler and said organosilane residues (ROS); one or more coordinating groups (GC) of the compound of formula (I) are substituted with an iron precursor in ionic form (Fe 3+) to form a chelate; separating the compound of formula (II) WF-O-ROS-GC-Fe obtained; The present invention is represented by a method including at least

[0029] A third aspect of the present invention is a process for the preparation of a vulcanizable elastomeric compound for a tire, comprising: a mixing step (1) of at least one elastomeric polymer and at least one additive for elastomeric compounds other than a vulcanizing agent to obtain a non-vulcanizable elastomeric compound; a step (2) of mixing said non-vulcanizable elastomeric compound and at least one vulcanizing agent to obtain a vulcanizable elastomeric compound; removing the vulcanizable elastomeric compound; 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. Represented by the method.

[0030] A fourth aspect of the present invention is represented by a vulcanizable elastomeric compound obtainable according to the process of the third aspect of the present invention.

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

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

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

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

[0035] As used herein, the term "elastomeric polymer" or "rubber" or "elastomer" means a natural or synthetic polymer which, after vulcanization, at room temperature can be repeatedly stretched to at least twice its original length and will forcefully return to nearly its original length substantially immediately after removal of the tensile load (according to the standard definition for rubber in ASTM D1566-11).

[0036] As used herein, the term "reinforcing filler" refers to reinforcing materials typically used in the sector to improve the mechanical properties of tire rubber, preferably selected from among carbon black, conventional silica, for example silica from sand precipitated with strong acids, preferably amorphous, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicates, kaolin, silicate fibers and mixtures thereof.

[0037] As used herein, the term "white filler" refers to conventional reinforcing materials used in the sector, selected from among conventional silicas and silicates, optionally modified and / or derivatized by acid treatment, such as sepiolite, palygorskite, also known as attapulgite, montmorillonite, alloysite, 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 the white filler, eliminating water or alcohol, to form an oxygen bridge (-O-), typically a hydroxyl group (-OH) or an alkoxy group (-OR), where R represents a linear or branched alkyl chain having 1 to 6 carbon atoms.

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

[0040] As used herein, the term "coordinating group" refers to an ionic form of iron, Fe, such as nitrogen, oxygen, or sulfur. 3+ indicates a functional group containing an atom capable of forming a coordinate bond with

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

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

[0043] As used herein, the term "non-vulcanizable elastomeric compound" refers to a product obtained by mixing at least one elastomeric polymer with at least one of the additives commonly used in the preparation of tire compounds, other than a vulcanizing agent. Non-vulcanizable elastomeric compounds are sometimes referred to as phase (1) elastomeric compounds.

[0044] As used herein, the term "vulcanizable elastomeric compound" refers to an elastomeric compound that is ready for vulcanization and that incorporates all additives, including vulcanizing agents. Vulcanizable elastomeric compounds are sometimes referred to as phase (2) elastomeric compounds.

[0045] As used herein, the term "vulcanized elastomeric compound" means a material obtained by vulcanization of a vulcanizable elastomeric compound.

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

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

[0048] The mixing step (1) is also referred to as the "non-productive step" because the components of the compound except for the crosslinking agent (eg, sulfur and accelerator) are delivered to the mixing device.

[0049] The mixing step (2) is conversely referred to as the productive step, in which the elastomeric compound obtained from step (1) and vulcanization additives capable of supporting and / or controlling crosslinking are fed into a mixing device to provide a vulcanizable elastomeric compound.

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

[0051] [Figure 1] 1 shows a radial half section of a tire for a vehicle wheel according to the invention; [Figure 2] FIG. 1 shows a Cartesian graph of the cure curves of elastomeric compounds RIF1, CON1 and INV1 described in Example 2. [Figure 3]FIG. 1 illustrates the nominal molar ratio (nFe(precursor) / nAPTES) used in the synthesis of the SiO2-APTESx-FeY material versus the actual molar ratio (nFe / nAPTES) determined in the SiO2-APTESx-FeY material. The black dashed line represents the ideal situation that would exist if the two ratios were matched. DETAILED DESCRIPTION OF THE INVENTION

[0052] The methods for the preparation of compounds of formula (II) according to the present invention are illustrated in detail below.

[0053] The method may be carried out in accordance with one or more of the following preferred embodiments, taken alone or in combination with one another, in particular with 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. The present invention is characterized by the use of a coupling agent having the formula:

[0054] The method of the present invention comprises: providing a white filler (WF); Formula (I): GR-ROS-GC (I) wherein GR represents one or more reactive groups capable of forming oxygen (—O—) bridges with the surface of the white filler, ROS represents an organosilane residue, and GC represents one or more coordinating groups. providing a coupling agent having Ionic iron precursor (Fe 3+ ) preparing a reacting a white filler (WF) with one or more reactive groups (GR) of said compound of formula (I) to form oxygen (—O—) bridges between said white filler and said organosilane residues (ROS); one or more coordinating groups (GC) of the compound of formula (I) are substituted with an iron precursor in ionic form (Fe 3+) to form a chelate; separating the compound of formula (II) WF-O-ROS-GC-Fe obtained; 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, alloysite, etc., and mixtures thereof; more preferably, it is silica.

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

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

[0059] An example of a suitable commercially available silica is the 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 viscosity of at least 120 m 2 / g, more preferably at least 140m 2 / g specific surface area (BET).

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

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

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

[0064] Preferred examples of GC coordinating groups represented by heteroatom-containing functional groups include either linear or branched alkyl chains containing one or more heteroatoms within or at the end of the alkyl chain, such as those of the formula -C n H 2n -XC m H 2m -Y or -C m H 2m -Y, wherein n and m, which may be equal or different, are integers from 1 to 6 (inclusive), 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 compounds represented by formula (I) include those represented by the following general formulae (Ia) and (Ib): (R)3Si-C n H 2n -XC m H 2m -Y (Ia) (R)3Si-C m H 2m -Y (Ib) wherein the R groups, which are equal or different, are selected from alkyl or alkoxy groups having 1 to 4 carbon atoms, with the proviso that at least one of the R groups is an alkoxy group; n and m, which are equal or different, are integers from 1 to 6, inclusive; X is a group selected from mercapto and amino; and Y is a group selected from mercapto, amino, dithiocarbamate, and carboxylic. is expressed by

[0066] Compounds that can be used in the present invention include (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)methylthioxysilane, N-cyclohexyl(aminomethyl)triethoxysilane, N-cyclohexyl-3-aminopropyl-trimethoxysilane, 3-(2-aminomethylamino)propyl-triethoxysilane, N-(n-butyl) N-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-(2-(2-aminoethylamino)ethylamino)propyltrimethoxysilane, N-(n-butyl)-3-aminopropyltriethoxysilane, N,N-diethylaminopropyltrimethoxysilane, N,N-dimethylaminopropyltrimethoxysilane, butylaminomethyltriethoxysilane, N-cyclohexyl(aminomethyl)trimethoxysilane, 2-aminoethylaminomethyltriethoxysilane, diethylaminomethyltriethoxysilane, (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+ The precursors of ) are Fe2O3, Fe(OH)3, and Fe in anhydrous or hydrated forms. 3+ The ferric iron salt may be, for example, an organic or inorganic salt 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, ferric lactate, and the like.

[0069] The reaction step between the white filler and the coupling agent of formula (I) is carried out hot in the solvent phase by first dispersing the white filler in a suitable solvent, then adding the coupling agent and allowing it to react 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 sodium hydroxide solution. 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, and 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 of between 12 and 24 hours. The white filler thus activated is separated by conventional separation techniques (filtration, centrifugation, etc.) and then subjected to freeze-drying.

[0072] The reaction between the white filler and the coupling agent is preferably carried out at a temperature greater than 40° C., more preferably greater than 60° C., and even more preferably greater than 80° C. The reaction temperature is preferably less than 200° C., more preferably less than 180° C., and even more preferably less 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, and 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 of between 12 and 24 hours.

[0074] The reaction product, represented by the functionalized white filler, is isolated 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, was then treated with an ionic iron precursor (Fe 3+ ) to form a chelate represented by formula (II):

[0076] The reaction begins by first dispersing the functionalized white filler (WF-O-ROS-GC) in a suitable solvent, followed by dissolving (Fe 2( Ionic iron precursors such as (Fe SO4)3*xH2O3+ ) and reacting it until the reaction is complete.

[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 above 40° C., more preferably above 60° C., even more preferably above 80° C. The reaction temperature is preferably below 200° C., more preferably below 180° C., even more preferably below 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, and 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 of 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] The process for preparing the vulcanizable elastomeric compound for tires according to the present invention is illustrated in detail below.

[0082] The method may comprise one or more of the following preferred embodiments, taken alone or in combination with one another, in particular the following 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 coordinating groups that form a chelate with ionic iron, and Fe represents ionic iron (Fe) coordinated with the coordinating groups. 3+ ) represents The present invention is characterized by the use of a compound represented by

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

[0084] The process of the present invention, when discontinuous, can be carried out in one or more mixers, preferably in a single mixer.

[0085] The process according to the invention comprises a step (step 1) of mixing at least one diene elastomeric polymer with at least one additive for elastomeric compounds which is not a vulcanizing agent.

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

[0087] Generally, no vulcanizing agents are added in the mixing step (1), and preferably no vulcanization accelerators or even retarders are added.

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

[0089] Preferably, the compound of formula (II) of the present invention is delivered in its entirety 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 period between 2 and 20 minutes.

[0091] Before proceeding to step (2), it may be advantageous to perform a drain and / or rest step of the non-vulcanizable elastomeric compound to allow any reaction to go to completion.

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

[0093] In the 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 the compound of formula (II) of the present invention can be added if they have not already been completely delivered to the mixing step (1).

[0094] In step (2) of the process of the present invention, the mixing temperature is generally kept below 160°C, preferably below 140°C, more preferably below 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 period between 2 and 10 minutes.

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

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

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

[0099] Preferably, the diene elastomeric 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, emulsion or gas phase polymerization of one or more conjugated diolefins, optionally mixed with at least one comonomer in an amount not exceeding 60% by weight selected from monovinylarenes and / or polar comonomers.

[0101] The conjugated diolefin generally contains 4 to 12, preferably 4 to 8, carbon atoms and may be selected, for example, from the group comprising 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, with 1,3-butadiene and isoprene being particularly preferred.

[0102] The monovinylarenes that may optionally be used as comonomers generally contain 8 to 20, 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-tolylstyrene, 4-(4-phenylbutyl)styrene, and mixtures thereof. Styrene is particularly preferred.

[0103] Polar comonomers that may optionally be used may be selected, for example, from 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 elastomeric 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 1,4-cis content), 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 vulcanizable elastomeric compound may optionally contain an elastomeric polymer of one or more monoolefins with an olefinic comonomer or its derivative. The monoolefin may be selected from ethylene and α-olefins, typically containing 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and mixtures thereof. Preferred are copolymers of ethylene and α-olefins, optionally with a diene; and isobutene homopolymers or copolymers thereof, optionally with a minor amount of at least partially halogenated diene. The optional diene typically 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, vinylnorbornene, and mixtures thereof. Among these, the following are particularly preferred: ethylene / propylene (EPR) copolymers or ethylene / propylene / diene (EPDM) copolymers; polyisobutene; butyl rubber; halobutyl rubber, in particular chlorobutyl or bromobutyl rubber; or mixtures thereof.

[0106] Diene elastomeric polymers or elastomeric polymers functionalized by reaction with suitable terminating or coupling agents may also be used. In particular, diene elastomeric polymers obtained by anionic polymerization in the presence of organometallic initiators, especially organolithium initiators, may be functionalized by reacting residual organometallic groups from the initiator with suitable terminating or coupling agents, such as imines, carbodiimides, alkyltin halides, substituted benzophenones, alkoxysilanes or aryloxysilanes.

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

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

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

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

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

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

[0113] The elastomeric compounds of the present invention may contain in admixture one or more vulcanizing agents as defined above.

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

[0115] In the process 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 accelerators may be present in the vulcanizable elastomeric compound in a total amount generally ranging between 0.05 phr and 10 phr, preferably between 0.1 phr and 5 phr.

[0119] The elastomeric compounds of the present invention may contain in admixture one or more accelerators as defined above.

[0120] In the process 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] Retarders may be present in the vulcanizable elastomeric compound in an amount generally ranging between 0.05 phr and 2 phr.

[0123] The elastomeric compounds of the present invention may contain in admixture one or more retarders as defined above.

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

[0125] In the method of the present invention, the reinforcing filler is selected from carbon black, conventional silica, sand precipitated with strong acids, preferably amorphous, hydrotalcite, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicate, kaolin, silicate fibers and mixtures thereof, to name a few.

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

[0127] Carbon black is standard tire grade or 20m 2 / g or more, preferably 50m 2 / g (measured according to ASTM D6556-16 standard).

[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 fillers may be present in the vulcanizable elastomeric compound in an amount generally ranging between 0 phr and 120 phr, preferably between 3 phr and 80 phr.

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

[0132] For some applications, the elastomeric compounds prepared according to the methods 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 elastomeric compounds of the present invention may contain in admixture one or more reinforcing fillers as defined above.

[0134] In the process of the present invention, phenylenediamines, diphenylamines, dihydroquinolines, phenols, benzimidazoles, hydroquinones and derivatives thereof may be used as antioxidants, optionally in mixtures.

[0135] In the method of the present invention, the antioxidant is preferably 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 N,N'-ditolyl-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, preferably it is N-(1,3-dimethyl-butyl)-N'-phenyl-p-phenylenediamine (6PPD).

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

[0137] The antioxidants may be present in the vulcanizable elastomeric compound in a total amount generally ranging between 0 phr and 20 phr, preferably between 0.5 phr and 10 phr.

[0138] In the process 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 Repsol's N-paraffin mixture and Antilux® 654 microcrystalline wax from Rhein Chemie.

[0140] The waxes may be present in the vulcanizable elastomeric compound in a total amount generally ranging between 0 phr and 20 phr, preferably between 0.5 phr and 5 phr.

[0141] In the process of the present invention, to further improve processability, the elastomeric compound may be blended with at least one plasticizer, typically selected from mineral oils, vegetable oils, synthetic oils, polymers with low molecular weights, and mixtures thereof, such as aromatic oils, naphthenic oils, phthalates, soybean oil, and mixtures thereof. The amount of plasticizer typically ranges from 0 phr to 70 phr, preferably from 5 phr to 30 phr. Preferably, the plasticizer, if present, is added during the polymer chewing step.

[0142] A fourth aspect of the present invention is represented by a vulcanizable elastomeric compound obtainable according to the process of the third aspect of the present invention.

[0143] In the elastomeric compound according to the present invention, iron is bonded by a coordinate bond to form the compound represented by formula (II) of the present invention, Fe 3+ It exists in ionic form as iron (Fe), but not 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) spectroscopy, as described in the experimental part.

[0145] The vulcanizable elastomeric compounds of the present invention may be incorporated into one or more components of a tire.

[0146] Thanks to the method of the present invention, it is possible to eliminate the zinc incorporated in the compounds without worsening or even improving their performance compared to comparable conventional compounds, with important benefits for the environment.

[0147] According to a fifth aspect of the present invention, the elastomeric compounds of the present invention are applied to tire components such as treads, underlayers, wear-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 invention consists of a vulcanizable compound according to the invention (green component) or a vulcanized compound obtained by vulcanization thereof (vulcanized component).

[0149] A sixth aspect of the present invention is a tyre for a vehicle wheel including at least one of the components set out above.

[0150] Preferably, the tyre for vehicle wheels of the present invention comprises at least one tyre component consisting of a vulcanizable elastomeric compound (green component) according to the second aspect of the present invention or a vulcanized elastomeric compound obtainable by vulcanization thereof.

[0151] In one embodiment, the vehicle tire according to the invention comprises: a carcass structure including at least a carcass ply having opposed lateral edges associated with each bead structure; - optionally a pair of sidewalls each applied at an axially outer position on a lateral surface of the carcass structure, - optionally a belt structure applied in a radially outer position relative to the carcass structure; - a tread band applied in a radially outer position relative to said carcass structure or, if present, to the belt structure; - optionally a layer of elastomeric material, called an underlayer, applied in a position radially inward relative to said tread band; At least At least one component selected from said sidewall pair, said underlayer and said tread band comprises or preferably consists of an elastomeric compound according to the invention.

[0152] An embodiment according to the invention relates to tires for high performance vehicles (HP, SUV and UHP), at least one component of which is preferably selected from the underlayer, the sidewall and the tread band, comprises or preferably consists of an elastomeric compound according to the invention.

[0153] An embodiment according to the invention relates to a tire for heavy vehicles, at least one component of which is preferably selected from the underlayer, the sidewall and the tread band, comprises or preferably consists of an elastomeric compound according to the invention.

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

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

[0156] Tires for bicycle wheels typically include a carcass structure wrapped around a pair of bead cores at the beads and a tread band positioned radially outward relative to the carcass structure.

[0157] The carcass structure is intended to withstand inflation pressure and support the weight of the bicycle and cyclist. 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 angled relative to one another to form a cross structure.

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

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

[0160] The tire according to the invention can be summer or winter or all season.

[0161] The tire according to the present invention comprises: - building a green tire component on at least one forming drum; - Shaping, molding and vulcanizing tires Including, Wherein constructing at least one of the components of a green tire includes: - producing at least one green component comprising, or preferably consisting of, the vulcanizable elastomeric compound of the present invention; The process can be carried out according to the following steps:

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

[0163] In Figure 1, "a" indicates the axial direction, "X" indicates the radial direction, and in particular, XX indicates the contour of the equatorial plane. For simplicity, Figure 1 shows only a portion of the tire, the remaining portion not shown being identical and symmetrically arranged with respect to the equatorial plane "XX".

[0164] The four-wheel vehicle tire 100 includes at least one carcass structure including at least one carcass layer 101 having opposing end flaps engaged with respective annular fixing structures 102, referred to as bead cores, which are optionally associated with bead fillers 104.

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

[0166] The area of ​​the tire including the bead core 102 and the filler material 104 forms a bead structure 103 that is intended to secure the tire to a corresponding mounting rim, not shown.

[0167] The carcass structure is usually of the radial type, i.e. the reinforcing elements of at least one carcass layer 101 are arranged in a plane containing the tire's axis of rotation and substantially perpendicular to the tire's equatorial plane. Said reinforcing elements generally consist of textile cords, such as rayon, nylon, polyester (for example polyethylene naphthalate, PEN), etc. Each bead structure is associated with the carcass structure by turning up the opposite lateral edges of at least one carcass layer 101 around an annular fastening structure 102 to form a so-called carcass flap 101a, as shown in Figure 1.

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

[0169] Wear resistant strips 105, optionally made of an elastomeric compound, are placed at the outer positions of each bead structure 103.

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

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

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

[0173] A tread band 109 of vulcanized elastomeric compound is applied to the belt structure 106 at a radially outer position.

[0174] Additionally, each sidewall 108 of vulcanized elastomeric compound is applied at an axially outer position on the lateral surface of the carcass structure, with each sidewall 108 extending from one of the lateral edges of the tread 109 in each bead structure 103.

[0175] At its radially outer position, the tread band 109 has a rolling surface 109a intended to come into contact with the ground. Circumferential grooves connected by transverse notches (not shown in FIG. 1) are generally made on this surface 109a so as to define a plurality of blocks of various shapes and sizes distributed over the rolling surface 109a, represented flat in FIG. 1 for the sake of simplicity.

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

[0177] A strip of elastomeric compound 110, commonly known as a "mini-sidewall" of vulcanized elastomeric compound, can optionally be provided in the connection area between the sidewall 108 and the tread band 109, this mini-sidewall being generally obtained by co-extrusion with the tread band 109 and allowing an improved 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, commonly known as a "liner", may also be provided at a radially inward position relative to the carcass layer 101, which provides the necessary impermeability to the tire's inflating air.

[0179] The stiffness of the tire sidewall 108 can be improved by providing the bead structure 103 with a reinforcing layer 120 or additional strip-like insert, commonly known as a "flipper."

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

[0181] Flipper 120 typically includes a plurality of textile cords embedded within a layer of vulcanized elastomeric compound.

[0182] The bead structure 103 of the tire may include an additional protective layer or strip, commonly known by the term “chafer” 121 , which has the function of increasing the stiffness and integrity of the bead structure 103 .

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

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

[0185] Advantageously, the layer or sheet may extend over a surface that substantially corresponds to the extension surface of said belt structure.

[0186] In a preferred embodiment, a layer or sheet of an elastomeric compound as described above can be placed between said belt structure and said tread band, said additional layer or sheet preferably extending onto a surface that substantially corresponds to the extension surface of said belt structure.

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

[0188] According to an embodiment not shown, the tire may be a tire for a wheel of a motorcycle, typically a tire having straight portions with a high tread camber.

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

[0190] According to an embodiment not shown, the tire may be a tire for the wheels of large transport vehicles such as trucks, buses, trailers, vans, etc., generally vehicles for 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 the wheels of a truck or trailer.

[0191] Set forth below are descriptions of some preparation examples and comparative examples according to the present invention, which are given only as an illustration and non-limiting of the scope of the present invention.

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

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

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

[0195] CHNS analysis was performed on an Elementar VarioMICRO analyzer configured with CHNS. The published measurement uncertainty is 0.1%. Measurements were normalized to a sulfanilamide standard. The combustion column temperature is 1150°C, while the reduction column temperature is 850°C.

[0196] BET analysis was performed on a Micromeritics Tristar II porosity and surface area analysis instrument.

[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 variable output power up to 1750 W).

[0198] MDR rheometric analysis (according to ISO 6502): A rheometer Alpha Technologies MDR2000 type was used. Tests were carried out at 170°C for 10 minutes at an oscillation frequency of 1.66 Hz (100 oscillations per minute) and an oscillation amplitude of ±0.5° to measure the time required to achieve an increase of 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 elastomeric materials prepared in the previous examples were vulcanized to obtain specimens for analytical characterization and evaluation of dynamic mechanical properties.

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

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

[0202] Dynamic Modulus: Dynamic mechanical properties were measured in compression and tension using an Instron® dynamic device using the following method: Vulcanized elastomeric cylindrical composition specimens (length = 25 mm; diameter = 18 mm), preloaded in compression to a longitudinal deformation of up to 25% relative to their initial length and maintained at a given temperature (10°C, 23°C, or 100°C) throughout the test, were subjected to dynamic sinusoidal stresses with amplitudes of ±3.5% relative to the preload 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 loss factor (loss factor). The dielectric loss factor value was calculated as the ratio between the dynamic viscous modulus (E'') and the dynamic elastic modulus (E').

[0204] G (shear) dynamic moduli: They were measured using a Monsanto RPA rheometer 2000 according to the following method: Cylindrical test specimens with weights ranging from 4.5 to 5.5 g were obtained by punching out the vulcanizable elastomer compositions and vulcanizing them in the RPA instrument (at 170 °C for 10 minutes). The vulcanized samples were subjected to dynamic measurements of shear modulus (G') at 70 °C, 10 Hz frequency, and 0.1 and 10% strain. Dynamic elastic properties were expressed in terms of dynamic shear modulus (G'), dynamic viscous shear modulus (G''), and dielectric loss factor (loss factor) at 3 and 9% strain. The dielectric loss factor value was calculated as the ratio between the dynamic viscous shear modulus (G'') and the dynamic shear modulus (E').

[0205] Example 1 Preparation of functionalized silica Materials used Rhodia Zeosil® MP1165 precipitated silica (specific surface area BET 160 m) produced by Rhodia 2 / g), Coupling agent (APTES): (3-aminopropyl)triethoxysilane H2N(CH2)3Si(OC2H5)3 (99%) produced by Sigma Aldrich 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 consisted of a two-step process in which silica was first functionalized with a coupling agent, and after recovery, the anhydrous powder was reacted with an iron precursor (hydrated ferric sulfate) to give iron in ionic form (Fe ) via the formation of a chelate with the coordinating group GC. 3+ ) and combine it with

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

[0208] The above preparation and characterization by ATR-FTIR, TGA and CHNS analyses of the functionalized silica (SiO2-APTES) obtained in the first step are similar to those described in WO 2020 / 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 analyses made it possible to confirm the functionalization of the 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 at 100 °C for 20 min under stirring to obtain a homogeneous suspension. Then, an appropriate amount of iron precursor (Fe2(SO4)3*xH2O) was added. The amount of iron precursor used was determined based on the assumption that iron ions cannot directly bond with the surface of the silica nanoparticles, and molar ratios of Fe / APTES (n) were equal to 1:20, 1:10, 1:2, 1:1, and 2:1. Fe(precursor) / n APTES ) was taken into account in the calculation.

[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 eliminate unreacted salts, and dried at 80 °C for 12 hours.

[0213] In this way, SiO2-APTES x -Fe Ywhere the subscripts Y and X represent the nominal molar ratio Fe / APTES (n Fe(precursor) / n APTES Five different catalysts, designated [[(R)- ...

[0214] Characterization of the obtained materials ICP-OES - Inductively Coupled Plasma Optical Emission Spectroscopy This characterization technique utilizes Fe, which is immobilized on silica nanoparticles using an amine ligand (APTES). 3+ This allowed the determination of the amount of ions and, by utilizing the analysis of materials prepared with different iron starting from metal precursors with different contents, allowed the estimation of the type of metal-ligand coordination.

[0215] ICP analysis was performed using a Perkin Elmer Optima 7000DV spectrometer (software controlled by WinLab32) coupled to a microwave digestion system. For each analysis, 0.2 g of powder material was finely ground and then dissolved in an acid solution consisting of 34 mL of HNO, 3 mL of HCl, and 1 mL of HF to prepare the sample. The sample was then treated in the digestion system in the following steps: i) 8 min at 160 °C, ii) 5 min at 200 °C, and iii) 20 min at 200 °C. The solution was diluted with 12 mL of Milli-Q 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 shows the Fe content determined by ICP and TGA measurements for each of the five prepared catalysts. 3+ The number of ions and APTES molecules is indicated.

[0217] [Table 2]

[0218] Fe coordinated by APTES molecules 3+The amount of ions increased with increasing amounts of metal precursors used during synthesis. x -Fe Y The maximum n obtained in the material Fe / n APTES The molar ratio is always about 1, even in the presence of excess iron, while up to n Fe / n APTES = 0.5, the calculated molar ratio (n Fe / n APTES ) and nominal molar ratio (n Fe(precursor) / n APTES ) are almost identical (Fig. 3). This tendency is consistent with that of SiO2-APTES x -Fe Y In this study, we suggest that the iron metal center is preferentially coordinated by silica-anchored APTES molecules, even though double coordination cannot be ruled out if the amount of iron used during synthesis is incomplete compared to that of APTES.

[0219] TEM - Transmission Electron Microscopy Analysis The morphology of the activators was studied by TEM and TEM-EDX analysis, the latter of which makes it possible in particular to investigate the elemental composition of the materials.

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

[0221] From the analyses carried out, a substantially homogeneous distribution of iron was observed on the surface of the silica particles, accompanied by the presence of sulfur ions, which may originate from residual sulfate groups of the metal precursor, which almost certainly remain within the coordination sphere of the metal but do not affect its reactivity.

[0222] Example 2 Preparation of Elastomeric Compounds Table 1 below shows formulations of a reference compound (RIF1) containing silica and zinc oxide, a comparative compound (CON1) containing silica and ferric sulfate itself, and a compound according to the invention (INV1) containing the vulcanization activator SiO-APTES-Fe in a molar ratio of 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 components, and the comparative compound (CON1) is a compound made to demonstrate the inertness of common iron salts compared to the vulcanization activators used in the compound of the present invention (INV1).

[0224] [Table 3]

[0225] All ingredients except for the 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 removed. Then, the sulfur and accelerator (CBS) were added and mixing was carried out in an open roll mixer (second step).

[0226] The compounds in Table 1 were used to prepare specimens on which MDR rheometric measurements and (shear) dynamic modulus G were performed as described above.

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

[0228] [Table 4]

[0229] The results show that the compound of the present invention (INV1) containing the vulcanization activator SiO2-APTES2-Fe1 of the present invention 3+It was demonstrated that the compound has high vulcanization efficiency not only compared to a comparative compound (CON1) containing a common salt of , but also compared to a reference compound containing a conventional zinc-based vulcanization activator.

[0230] High G'(3%) and G'(9%) values ​​indicated high elasticity of the compound, which predicted high tire response and therefore better performance during its use. Low values ​​of dissipation factor (3%) and (9%) conversely indicated low hysteresis and therefore low rolling resistance of the tire.

[0231] Fe2(SO4)3 alone, i.e., without forming a metal complex with the organic ligands anchored to the silica surface, was unable to activate the vulcanization process, since low torque values ​​were obtained, resulting in poor mechanical properties.

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

[0233] FIG. 2 shows a Cartesian graph of the cure curves of the elastomeric compounds RIF1, CON1 and INV1.

[0234] The use of the compounds of the present invention as vulcanization activators resulted in a complete and homogeneous dispersion of iron in the subsequent vulcanization reaction, which is an undoubted advantage. Moreover, the absence of zinc made these mixtures sustainable from an environmental point of view, avoiding the release of zinc into the environment, which is toxic to aquatic organisms.

[0235] Example 3 Preparation of Elastomeric Compounds Table 3 below shows the formulations of reference compounds (RIF2 and RIF3) containing silica and varying amounts of zinc oxide, and of a compound according to the invention (INV2) containing a vulcanization activator SiO2-APTES2-Fe1 with a molar ratio Fe / APTES of 1:2 and no vulcanization accelerator (CBS), prepared as described in Example 1.

[0236] [Table 5]

[0237] All ingredients except for the 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 removed. If intended, the sulfur and accelerator (CBS) were then added and mixing was carried out in an open roll mixer (second step).

[0238] The compounds in Table 3 were used to prepare specimens on which MDR rheometric measurements and static moduli CA0.1, CA0.5 and CA1 were performed as described above.

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

[0240] [Table 6]

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

[0242] The compound of the present invention (INV2) exhibited higher Ca0.1, Ca0.5, and Ca1 values ​​than the reference compounds (RIF2 and RIF3), indicating good elasticity of the compound and predicting good response characteristics and handling of the tire and its greater durability in use conditions.

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

[0244] In this test, all compounds were free of added accelerators (CBS).

[0245] [Table 7]

[0246] All ingredients 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 removed. Then, sulfur was added and mixing was carried out in an open roll mixer (second step).

[0247] The compounds in Table 5 were used to prepare specimens on which MDR rheometric measurements and static moduli CA0.1, CA0.5, CA1 and CA3 were performed as described above.

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

[0249] [Table 8]

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

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

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

[0253] [Table 9]

[0254] All ingredients except for the 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 removed. If intended, the sulfur and accelerator (CBS) were then added and mixing was carried out in an open roll mixer (second step).

[0255] The compounds in Table 7 were used to prepare specimens on which MDR rheometric measurements, (shear) dynamic modulus G and static modulus CA0.1 were performed as described above.

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

[0257] [Table 10]

[0258] The results in Table 8 demonstrate that the vulcanization activator SiO2-APTES2-Fe1 of the present invention exhibits high vulcanization efficiency, even in the presence of different polymers and in the absence of an accelerator.

[0259] The values ​​Ca0.1, G' and MH, which indicate the vulcanization of the material, were all higher for the compound of the invention (INV4) than for 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 coordinating groups that form a chelate with ionic iron, and Fe represents ionic iron (Fe) coordinated with the coordinating groups. ３＋ ) is represented by A compound wherein said white filler WF is selected from the group consisting of silica and silicates in the form of fibers, films or granules.

2. 2. The compound according to claim 1, 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, alloysite, and mixtures thereof, optionally modified and / or derivatized by acid treatment.

3. 2. The compound of claim 1, wherein the coordinating group (GC) is a linear or branched alkyl chain containing one or more heteroatoms internal or at the end of the alkyl chain.

4. The coordination group GC has the formula -C ｎ H ２ｎ -X-C ｍ H ２ｍ -Y or -C ｍ H ２ｍ -Y, wherein n and m, which are equal or different, are integers from 1 to 6 (inclusive), X is a group selected from mercapto and amino, and Y is a group selected from mercapto, amino, dithiocarbamate, and carboxyl.

5. A process for preparing a compound of formula (II) according to claim 1, comprising: providing a white filler (WF), said white filler WF being selected from the group consisting of silica and silicates in the form of fibers, films or granules; The following formula (I): GR-ROS-GC (I) wherein GR represents one or more reactive groups capable of forming oxygen (—O—) bridges with the surface of the white filler, ROS represents an organosilane residue, and GC represents one or more coordinating groups. providing a coupling agent having Ionic iron precursor (Fe ３＋ ) and reacting a white filler (WF) with one or more reactive groups (GR) of said compound of formula (I) to form oxygen (—O—) bridges between said white filler and said organosilane residue (ROS); one or more coordinating groups (GC) of the compound of formula (I) are substituted with an iron precursor in ionic form (Fe ３＋ ) to form a chelate; isolating the compound of formula (II) WF-O-ROS-GC-Fe obtained; The method includes at least

6. 6. The method according to claim 5, 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, alloysite, and mixtures thereof, optionally modified and / or derivatized by acid treatment.

7. 10. The compound of claim 1 or the method of claim 5, wherein the coordinating group (GC) is a linear or branched alkyl chain containing one or more heteroatoms internal or at the end of the alkyl chain.

8. The coordination group GC has the formula -C ｎ H ２ｎ -X-C ｍ H ２ｍ -Y or -C ｍ H ２ｍ 8. The method of claim 7, wherein n and m are equal or different integers from 1 to 6 (inclusive), X is a group selected from mercapto and amino, and Y is a group selected from mercapto, amino, dithiocarbamate, and carboxyl.

9. The method of claim 5, wherein the reactive group GR is an alkoxy group having 1 to 4 carbon atoms.

10. The coupling agent is represented by 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 R groups, which are equal or different, are selected from alkyl or alkoxy groups having 1 to 4 carbon atoms, with the proviso that at least one of the R groups is an alkoxy group; n and m, which are equal or different, are integers from 1 to 6, inclusive; X is a group selected from mercapto and amino; and Y is a group selected from mercapto, amino, dithiocarbamate, and carboxyl. The method of claim 5 , wherein the

11. The coupling agent may be (3-aminopropyl)triethoxysilane (APTES), (3-aminopropyl)trimethoxysilane, 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 6. The method of claim 5, wherein the silane is selected from the group consisting of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-(2-(2-aminoethylamino)ethylamino)propyltrimethoxysilane, N-(n-butyl)-3-aminopropyltriethoxysilane, N,N-diethylaminopropyltrimethoxysilane, N,N-dimethylaminopropyltrimethoxysilane, butylaminomethyltriethoxysilane, N-cyclohexyl(aminomethyl)trimethoxysilane, 2-aminoethylaminomethyltriethoxysilane, diethylaminomethyltriethoxysilane, (3-mercaptopropyl)triethoxysilane and (3-mercaptopropyl)trimethoxysilane.

12. 12. The method of claim 11, 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.

13. The ionic iron precursor (Fe ３＋ ) is ferric oxide (Fe ２ O ３ ), ferric hydroxide (Fe(OH) ３ ), and Fe ３＋ 6. The method of claim 5, wherein the organic or inorganic salt is selected from the group consisting of:

14. 14. The method of claim 13, 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.

15. 1. A process for the preparation of a vulcanizable elastomeric compound for a tire, comprising: a mixing step (1) of at least one elastomeric polymer and at least one additive for elastomeric compounds other than a vulcanizing agent to obtain a non-vulcanizable elastomeric compound; a step (2) of mixing said non-vulcanizable elastomeric compound and at least one vulcanizing agent to obtain a vulcanizable elastomeric compound; - removing said vulcanizable elastomeric compound; At least In at least one of the mixing steps (1) and (2), a compound of formula (II) according to claim 1 is added. method.

16. A vulcanizable elastomeric compound comprising at least one elastomeric polymer, at least one additive for elastomeric compounds, at least one vulcanizing agent, and a compound of formula (II) as described in claim 1.

17. A tire component comprising the vulcanizable elastomeric compound of claim 16 or a vulcanized compound obtained by vulcanization thereof.

18. A tire for a vehicle wheel, comprising the components described in claim 17.

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