Tire for vehicle wheel

Abstract

The invention relates to novel adducts between lignin and pyrrole derivatives of formula (I), in which R1 to R4 and W have the meanings as defined in the description, which adducts are to be used as reinforcing fillers for vulcanizable elastomer compositions suitable for the production of tyres for vehicle wheels. # imgabs0 #

Description

Field of the Invention

[0001] The present invention relates to a novel adduct between lignin and a pyrrole derivative, which adduct is to be used as a reinforcing filler for a vulcanizable elastomeric composition suitable for the production of tires for vehicle wheels, and to a tire for vehicle wheels comprising at least one structural component comprising a vulcanized elastomeric compound obtained by vulcanizing a vulcanizable elastomeric composition comprising such an adduct between lignin and a pyrrole derivative as a reinforcing filler partially or completely replacing a conventional reinforcing filler. Prior Art

[0002] A tire for vehicle wheels generally comprises a carcass structure comprising at least one carcass ply having opposite lateral edges associated with respective bead structures, a belt structure applied at a radially outer position of the carcass structure, and a tread provided at a radially outer position of the belt structure.

[0003] In addition to supporting the weight of the vehicle, the carcass structure is designed to resist the inflation pressure and all the lateral and longitudinal stresses to which the running tire is subjected after contact with the road surface.

[0004] The belt structure is designed to transmit the above-mentioned lateral and longitudinal stresses to the carcass structure and contribute to conferring the desired characteristics of structural strength, grip, driving stability, controllability, directionality, road grip, comfort, and to maintain these performances over time.

[0005] The bead structure is designed to withstand the circumferential, lateral and combined stresses transmitted between the rim and the tire under normal use conditions (such as during acceleration, braking and when turning, even possibly at high speed).

[0006] Several structural components of the finished tire comprise a vulcanized elastomeric compound. The matrix of the vulcanized elastomeric compound is made by vulcanizing an elastomeric composition comprising at least one diene elastomeric polymer and at least one reinforcing filler to improve the characteristics of the resulting crosslinked product, in particular the mechanical properties.

[0007] Due to its high reinforcing efficiency, carbon black is a particularly used reinforcing filler. However, carbon black represents a non-renewable raw material, mainly resulting from the partial combustion process of fossil fuels (mainly naphtha, methane gas and other hydrocarbons). In addition, carbon black may have environmental concerns since it is a potential pollutant if not properly treated. Therefore, replacing or reducing the use of carbon black represents not only an objective of interest to tire manufacturers, but also an objective of common interest to the community.

[0008] The Applicant has recognized the need to supply tyres and their components that are more ecologically sustainable and ecocompatible, for example, by reducing or replacing raw materials from petroleum with raw materials produced from renewable sources, with the aim of maintaining and possibly improving the performance of the tyres.

[0009] Among the most abundant biopolymers from renewable sources applied in tyres, mention may be made of starch, cellulose, lignin and hemicellulose as examples. In the past, various attempts have been made to use some of these materials as reinforcing agents, which also have a lower specific gravity than traditional reinforcing fillers. For example, lignin has been used as such or modified in various ways as a reinforcing filler in tyre compounds.

[0010] Lignin is an organic polymer complex having a three-dimensional polymeric structure composed of phenylpropane units and belongs to the category of so-called phenylpropanoid compounds.

[0011] Lignin has a very different composition and molecular weight, both of which are functions of the selected biomass and the method of obtaining them. The composition differs both in terms of functional groups (mainly phenolic, hydroxyl and carboxylic acid groups) and molecular weight.

[0012] Research efforts have been made in the academic and industrial fields to replace traditional fillers with bio-fillers, especially lignin.

[0013] Vehicle wheel tyres containing lignin are described in patent applications US2010 / 0204368, WO2009 / 145784, JP2008 / 308615, JP2010 / 242023, JP2010 / 248282, JP2014 / 129509, CN102718995, CN103756060, WO2014 / 097108, WO2017 / 109672, WO2022 / 144759, IT102021000029213 and IT102021000029831, and are also described in patents GB723751, GB836393, US2610954, US2802815, US2906718, US3079360, US3163614, US3282871, US3296158, US3312643, US3364158, US3817974, US3984362 and US3991022.

[0014] Hait, S. et al. (2021). Treasuring was te lignin as superior reinforcing filler in high cis-polybutadiene rubber: A direct comparative study with standard reinforcing silica and carbon black. Journal of Cleaner Production, Vol. 299, 126841 discloses the use of bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) as a coupling agent in a rubber composition, which uses Mg-lignin, Na-lignin, and sulfate lignin as reinforcing fillers based on 100 phr of butadiene rubber (BR). It was found that the tensile properties of the sulfate lignin-based compound were excellent or even better compared to the standard silica-silane system and equivalently loaded reinforcing carbon black. Summary of the Invention

[0016] The Applicant has conducted in-depth research activities to find a method for producing tire compounds using lignin to partially or fully replace carbon black in elastomeric compositions for structural components commonly used in tires, with the aim of reducing the hysteresis of the composition itself, thereby reducing energy dissipation and fuel consumption during tire use, while still maintaining or improving static and dynamic mechanical properties.

[0017] Starting from the work of Hai t, S. et al., the Applicant recognized that TESPT releases ethanol when condensing with the functional groups of the filler, and the sulfur atoms contained in TESPT may cause premature vulcanization during mixing and during the non-productive mixing steps of the elastomeric composition.

[0018] The Applicant has carried out extensive work on achieving adducts between pyrrole derivatives and carbon black or silica reinforcing fillers, with the aim of increasing their compatibility with elastomeric compositions, as described in WO2016 / 050887, WO2018 / 087685, WO2018 / 087688, WO2019 / 162873, and WO20 / 225595.

[0019] The Applicant believes that pyrrole derivatives can be used to prepare adducts with lignin, which can be used to partially replace reinforcing fillers, especially carbon black, resulting in a hybrid reinforcing filler system that can act as a reinforcing filler system in elastomeric compositions suitable for tire compounds.

[0020] After extensive experimentation, the Applicant surprisingly found that elastomeric compositions comprising such a hybrid reinforcing filler system exhibit unexpected improved static and dynamic mechanical properties and similar or improved hysteresis compared to elastomeric compositions comprising conventional carbon black reinforcing fillers.

[0021] Continuing the experiments, the Applicant also surprisingly found good results with respect to the fracture properties of elastomeric compositions comprising only an adduct of lignin and a pyrrole derivative as a reinforcing filler.

[0022] Accordingly, in its first aspect, the present invention relates to an adduct of lignin and a pyrrole derivative, wherein the lignin comprises at least one functional group selected from the group consisting of hydroxyl (-OH), carboxyl (-COOH), ester (-COOR) and aldehyde (-CHO), and wherein the pyrrole derivative has the following general formula (I):

[0023]

[0024] wherein

[0025] R1 - R4 are independently selected from a hydrogen atom, a C1 - C3 alkyl group, a straight-chain or branched C2 - C 10 alkenyl or alkynyl group, an aryl group, a straight-chain or branched C7 - C 16 alkyl-aryl group, a straight-chain or branched C7 - C 16 alkenyl-aryl group, a straight-chain or branched C7 - C 16 alkynyl-aryl group, a heteroaryl group, -CO-NHW' and -CO-OW”;

[0026] W” is selected from a hydrogen atom, a straight-chain or branched C1 - C 10 alkyl group, a straight-chain or branched C2 - C 10 alkenyl or alkynyl group, an aryl group, a straight-chain or branched C7 - C 16 alkyl-aryl group, a straight-chain or branched C7 - C 16 alkenyl-aryl group, a straight-chain or branched C7 - C 16 alkynyl-aryl group, and a heteroaryl group,

[0027] W and W' are independently selected from a hydrogen atom, a straight-chain or branched C1 - C 10 alkyl group, a straight-chain or branched C2 - C 10 alkenyl or alkynyl group, a straight-chain or branched C7 - C 16 alkyl-aryl group, a straight-chain or branched C7 - C 16 alkenyl-aryl group, a straight-chain or branched C7 - C 16 alkynyl-aryl group, a heteroaryl group, an aryl group, a cyclohexyl group and a residue having the following formula (II):

[0028]

[0029] wherein M, Q and J are independently selected from a hydrogen atom, an amino group, a hydroxyl group, a linear or branched C1-C 10 alkyl group, a linear or branched C2-C 10 alkenyl or alkynyl group and a residue having the following formula (III):

[0030]

[0031] wherein I is an integer from 0 to 12, and R5 and R6 are independently selected from a hydrogen atom, a linear or branched C1-C 10 alkyl group, a linear or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 16 alkyl-aryl group, a linear or branched C7-C 16 alkenyl-aryl group, a linear or branched C7-C 16 alkynyl-aryl group, a heteroaryl group, a carboxyl group, and -(CH2) o -S-R 16 , where o is an integer from 0 to 2, and R 16 is selected from a hydrogen atom or a C1-C3 alkyl group, and Gr is selected from the group consisting of the following residues (IV) to (IX):

[0032]

[0033] wherein m is an integer from 1 to 2, n is an integer from 1 to 4, p is an integer from 2 to 4, q is an integer from 1 to 30, and R7-R 15 are independently selected from a hydrogen atom, a linear or branched C1-C 10 alkyl group, a linear or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 16 alkyl-aryl group, a linear or branched C7-C 16 alkenyl-aryl group, a linear or branched C7-C 16 alkynyl-aryl group, and a heteroaryl group, and R 11 -R 13 can also be a linear or branched C1-C 10 alkoxy group.

[0034] In its second aspect, the present invention relates to a tire for a vehicle wheel, which comprises at least one structural component, said structural component comprising a vulcanized elastomeric compound obtained by vulcanizing a vulcanizable elastomeric composition, said vulcanizable elastomeric composition comprising:

[0035] (i) 100 phr of a composition comprising at least one diene elastomeric polymer selected from natural and synthetic diene elastomeric polymers,

[0036] (ii) 0 to 100 phr of a carbon black reinforcing filler,

[0037] (iii) 2 to 100 phr of an adduct of lignin and a pyrrole derivative according to the first aspect of the present invention, and

[0038] (iv) 0.1 to 12 phr of at least one vulcanizing agent.

[0039] In its third aspect, the present invention relates to a green tire structural component comprising a vulcanizable elastomeric composition, said vulcanizable elastomeric composition comprising:

[0040] (i) 100 phr of a composition comprising at least one diene elastomeric polymer selected from natural and synthetic diene elastomeric polymers,

[0041] (ii) 0 to 100 phr of a carbon black reinforcing filler,

[0042] (iii) 2 to 100 phr of an adduct of lignin and a pyrrole derivative according to the first aspect of the present invention, and

[0043] (iv) 0.1 to 12 phr of at least one vulcanizing agent.

[0044] In its fourth aspect, the present invention relates to an elastomeric composition comprising:

[0045] (i) 100 phr of a composition comprising at least one diene elastomeric polymer selected from natural and synthetic diene elastomeric polymers,

[0046] (ii) 0 to 100 phr of a carbon black reinforcing filler,

[0047] (iii) 2 to 100 phr of an adduct of lignin and a pyrrole derivative according to the first aspect of the present invention, and

[0048] (iv) 0.1 to 12 phr of at least one vulcanizing agent.

[0049] Definitions

[0050] According to the present invention, the term "adduct" should be understood to mean a compound obtained by combining two or more components mainly through covalent bonds and, to a lesser extent, through more labile intermolecular interactions such as ionic bonds, van der Waals forces, ion-dipole interactions, and hydrogen bonds. In particular according to the present invention, the term "adduct" refers to an adduct obtained from the interaction between a pyrrole derivative (i.e., a compound of formula (I) as defined herein) and lignin comprising at least one functional group selected from hydroxyl (-OH), carboxyl (-COOH), ester (-COOR), and aldehyde (-CHO) groups via covalent bonds and intermolecular interactions.

[0051] The term "elastomeric composition" refers to a composition comprising at least one diene elastomeric polymer and one or more additives, which provides an elastomeric compound suitable for tires and their components by mixing and possibly heating.

[0052] The components of the elastomeric composition are not usually introduced into the mixing mill simultaneously, but are typically added sequentially. In particular, the vulcanization additives, such as vulcanizing agents and possibly accelerators and retarders, are usually added in a downstream step relative to the incorporation and processing of all other components.

[0053] In the final vulcanizable elastomeric compound, due to the interaction of heat and / or mechanical processing with other components, the individual components of the elastomeric composition can be completely or partially altered or no longer be separately traceable as modified. The term "elastomeric composition" as used herein means the group comprising all the components used to prepare the elastomeric compound, whether or not they are actually present simultaneously, introduced sequentially, or then traceable in the elastomeric compound or the final tire.

[0054] The term "elastomeric polymer" denotes a natural or synthetic polymer that can be repeatedly stretched at room temperature to at least twice its original length after vulcanization and returns substantially immediately to approximately its original length upon removal of the stretching load (as defined by the ASTM D1566-11 standard terminology related to rubber).

[0055] The term "diene elastomeric polymer" denotes a polymer or copolymer resulting from the polymerization of one or more different monomers, at least one of which is a conjugated diene (conjugated diolefin).

[0056] The term "elastomeric compound" denotes a compound that can be obtained by mixing at least one elastomeric polymer with at least one additive typically used to prepare tire compounds and possibly heating.

[0057] The term "vulcanizable elastomeric compound" denotes an elastomeric compound ready for vulcanization, which can be obtained by incorporating all the additives (including vulcanization additives) into the elastomeric compound.

[0058] The term "vulcanized elastomeric compound" refers to the material obtainable by vulcanization of a vulcanizable elastomeric compound.

[0059] The term "green stock" denotes a material, compound, composition, component, or tire that has not been vulcanized.

[0060] The term "vulcanization" refers to the crosslinking reaction in natural or synthetic rubber induced by a crosslinking agent usually based on sulfur.

[0061] The term "vulcanizing agent" means a product capable of transforming natural or synthetic rubber into an elastic and resistant material by forming a three-dimensional network of intermolecular and intramolecular bonds. Typical vulcanizing agents are sulfur-based compounds such as elemental sulfur, polymeric sulfur, sulfur donor reagents such as bis[(trialkoxysilyl)propyl] polysulfides, thiurams, dithiomorpholines, and caprolactam disulfides.

[0062] The term "vulcanization accelerator" refers to a compound capable of reducing the duration and / or operating temperature of the vulcanization process, such as sulfenamides, thiazoles, dithiophosphates, dithiocarbamates, guanidines, and sulfur donors such as thiurams.

[0063] The term "vulcanization activator" means a product capable of further promoting vulcanization, causing it to occur in a shorter time and possibly at a lower temperature. Examples of activators are the stearic acid-zinc oxide system.

[0064] The term "vulcanization retarder" means a product capable of delaying the start of the vulcanization reaction and / or inhibiting unwanted secondary reactions, such as N-(cyclohexylthio)phthalimide (CTP).

[0065] The term "vulcanization package" refers to a vulcanizing agent and one or more vulcanization additives selected from vulcanization activators, accelerators, and retarders.

[0066] The term "reinforcing filler" refers to a reinforcing material commonly used in the art to improve the mechanical properties of tire rubber, preferably selected from carbon black, conventional silica such as silica from sand precipitated with strong acid, preferably amorphous silica, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicates, kaolin, silicate fibers, and mixtures thereof.

[0067] The term "mixing step (1)" refers to a step in the method for preparing an elastomer compound, in which, in addition to the vulcanizing agent fed in step (2), one or more additives can be incorporated by mixing and possibly heating. Mixing step (1) is also called the "non-productive step". There may be several "non-productive" mixing steps in the preparation of the compound, which can be designated as 1a, 1b, etc.

[0068] The term "mixing step (2)" refers to the next step in the method for preparing an elastomer compound, in which the vulcanizing agent and other additives in the possible vulcanization package are introduced into the elastomer compound obtained from step (1) and mixed in the material at a controlled temperature, usually at a compound temperature below 120 °C, to provide a vulcanizable elastomer compound. Mixing step (2) is also called the "productive step".

[0069] The term "structural component" of a tire refers to any layer of elastomeric material of the tire, including reinforcing elements. A structural component of a tire can be a layer included in a reinforcing structure (such as a carcass structure or a belt structure), or it can be a reinforcing layer (such as a zero-degree belt layer, a bead reinforcing layer or "overturning flap", a sidewall reinforcing layer or "bead wrapper").

[0070] The term "radial carcass structure" denotes a carcass structure including a plurality of reinforcing elements, each reinforcing element being placed substantially in a respective plane passing through the radius of the tire. Such reinforcing elements can be incorporated into a single carcass ply or into a number of carcass plies (preferably two carcass plies) radially superposed on one another.

[0071] The terms "radial" and "axial" and the expressions "radially inner / outer" and "axially inner / outer" refer respectively to a direction substantially parallel to the equatorial plane of the tire, and a direction substantially perpendicular to the equatorial plane of the tire, i.e. respectively to a direction substantially perpendicular to the axis of rotation of the tire and a direction substantially parallel to the axis of rotation of the tire.

[0072] The term "cross-belt structure" refers to a belt structure including a first belt layer and at least a second belt layer, the first belt layer including reinforcing elements substantially parallel to one another and inclined at a predetermined angle with respect to the equatorial plane of the tire, the second belt layer being disposed in a radially outer position with respect to the first belt layer and including reinforcing elements substantially parallel to one another but having an inclination opposite to that of the reinforcing elements of the first layer with respect to the equatorial plane of the tire.

[0073] The term "zero-degree belt structure" denotes a reinforcing layer including at least one reinforcing element wound around the belt structure according to a substantially circumferential winding direction (i.e., according to a winding direction having an inclination of less than 6° with respect to the equatorial plane of the tire).

[0074] The terms "circumferential" and "circumferentially" are used with reference to the direction of the annular extension of the tire (i.e., the rolling direction of the tire), which direction corresponds to a direction lying in a plane coinciding with or substantially parallel to the equatorial plane of the tire.

[0075] The "substantially axial direction" refers to a direction inclined at an angle between about 70° and about 90° with respect to the equatorial plane of the tire.

[0076] The "substantially circumferential direction" refers to a direction extending at an angle between about 0° and about 10° with respect to the equatorial plane of the tire.

[0077] For the purposes of this specification and the appended claims, the term "phr" (an acronym for parts per hundred rubber) denotes the number of parts by weight of a given elastomeric compound component relative to 100 parts by weight of elastomeric polymer, with no incremental oil being considered.

[0078] Unless otherwise specified, all percentages are by weight.

[0079] Pyrrole derivatives

[0080] The pyrrole derivatives useful in the present invention have the following general formula (I):

[0081]

[0082] wherein

[0083] R1-R4 are independently selected from a hydrogen atom, a C1-C3 alkyl group, a straight-chain or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a straight-chain or branched C7-C 16 alkyl-aryl group, a straight-chain or branched C7-C 16 alkenyl-aryl group, a straight-chain or branched C7-C 16 alkynyl-aryl group, a heteroaryl group, -CO-NHW' and -CO-OW”;

[0084] W” is selected from a hydrogen atom, a straight-chain or branched C1-C 10 alkyl group, a straight-chain or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a straight-chain or branched C7-C 16 alkyl-aryl group, a straight-chain or branched C7-C 16 alkenyl-aryl group, a straight-chain or branched C7-C 16 alkynyl-aryl group, and a heteroaryl group,

[0085] W and W' are independently selected from a hydrogen atom, a straight-chain or branched C1-C 10 alkyl group, a straight-chain or branched C2-C 10 alkenyl or alkynyl group, a straight-chain or branched C7-C 16 alkyl-aryl group, a straight-chain or branched C7-C 16 alkenyl-aryl group, a straight-chain or branched C7-C 16 alkynyl-aryl group, a heteroaryl group, an aryl group, a cyclohexyl group and a residue having the following formula (II):

[0086]

[0087] wherein M, Q and J are independently selected from a hydrogen atom, an amino group, a hydroxyl group, a straight-chain or branched C1-C 10 alkyl group, a straight-chain or branched C2-C 10 alkenyl or alkynyl group and a residue having the following formula (III):

[0088]

[0089] wherein I is an integer from 0 to 12, and R5 and R6 are independently selected from a hydrogen atom, a linear or branched C1-C 10 alkyl group, a linear or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 16 alkyl-aryl group, a linear or branched C7-C 16 alkenyl-aryl group, a linear or branched C7-C 16 alkynyl-aryl group, a heteroaryl group, a carboxyl group, and -(CH2) o -S-R 16 , where o is an integer from 0 to 2, and R 16 is selected from a hydrogen atom or a C1-C3 alkyl group, and Gr is selected from the group consisting of the following residues (IV) to (IX):

[0090]

[0091] where m is an integer from 1 to 2, n is an integer from 1 to 4, p is an integer from 2 to 4, q is an integer from 1 to 30, and R7-R 15 are independently selected from a hydrogen atom, a linear or branched C1-C 10 alkyl group, a linear or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 16 alkyl-aryl group, a linear or branched C7-C 16 alkenyl-aryl group, a linear or branched C7-C 16 alkynyl-aryl group, and a heteroaryl group, and R 11 -R 13 can also be a linear or branched C1-C 10 alkoxy group.

[0092] According to an embodiment of the present invention, R1-R4 are independently selected from a hydrogen atom, a C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 10 alkyl-aryl group, a linear or branched C7-C 10 alkenyl-aryl group, a linear or branched C7-C 10 alkynyl-aryl group, a heteroaryl group, -CO-NHW', and -CO-OW”.

[0093] According to an embodiment of the present invention, R1-R4 are independently selected from a hydrogen atom, a C1-C3 alkyl group, an aryl group, a heteroaryl group, -CO-NHW', and -CO-OW”.

[0094] According to an embodiment of the present invention, at least one of R1-R4 is selected from -CO-NHW' and -CO-OW”.

[0095] According to an embodiment of the present invention, W” is selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 10 alkyl-aryl group, a linear or branched C7-C 10 alkenyl-aryl group, a linear or branched C7-C 10 alkynyl-aryl group, and a heteroaryl group.

[0096] According to an embodiment of the present invention, W” is selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, and a heteroaryl group.

[0097] According to an embodiment of the present invention, W' is selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, a linear or branched C7-C 10 alkyl-aryl group, a linear or branched C7-C 10 alkenyl-aryl group, a linear or branched C7-C 10 alkynyl-aryl group, a heteroaryl group, an aryl group, a cyclohexyl group, and a residue of formula (II) as described above.

[0098] According to an embodiment of the present invention, W' is selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a heteroaryl group, an aryl group, a cyclohexyl group, and a residue of formula (II) as described above.

[0099] According to an embodiment of the present invention, R1-R4 are independently selected from a hydrogen atom, a C1-C3 alkyl group.

[0100] According to an embodiment of the present invention, W is selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, a linear or branched C7-C 10 alkyl-aryl group, a linear or branched C7-C 10 alkenyl-aryl group, a linear or branched C7-C 10 alkynyl-aryl group, a heteroaryl group, an aryl group, a cyclohexyl group, and a residue of formula (II) as described above.

[0101] According to an embodiment of the present invention, W is selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a heteroaryl group, an aryl group, a cyclohexyl group, and a residue of formula (II) as described above.

[0102] According to an embodiment of the present invention, M, Q, and J are independently selected from a hydrogen atom, an amino group, a hydroxyl group, a linear or branched C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, and a residue of formula (III) as described above.

[0103] According to an embodiment of the present invention, at least one of M, Q, and J is a residue of formula (III) as described above.

[0104] According to an embodiment of the present invention, at least two of M, Q, and J are residues of formula (III) as described above.

[0105] According to an embodiment of the present invention, R5 and R6 are independently selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 10 alkyl-aryl group, a linear or branched C7-C 10 alkenyl-aryl group, a linear or branched C7-C 10 alkynyl-aryl group, a heteroaryl group, a carboxyl group, or -(CH2) o -S-R 16 , where o is an integer from 0 to 2, and R 16 is selected from a hydrogen atom or a C1-C3 alkyl group.

[0106] According to an embodiment of the present invention, R5 and R6 are independently selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a carboxyl group, or -(CH2) o -S-R 16 , where o is an integer from 0 to 2, and R 16 is selected from a hydrogen atom or a C1-C3 alkyl group.

[0107] According to an embodiment of the present invention, R5 and R6 are independently selected from a hydrogen atom, a linear or branched C1-C3 alkyl group.

[0108] According to an embodiment of the present invention, R7-R 15 are independently selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 10 alkyl-aryl group, a linear or branched C7-C 10 alkenyl-aryl group, a linear or branched C7-C 10 alkynyl-aryl group, a heteroaryl group, and a carboxyl group, and R 11 -R 13 can also be a linear or branched C1-C5 alkoxy group.

[0109] According to an embodiment of the present invention, R7-R 15 are independently selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a heteroaryl group, and a carboxyl group, and R 11 -R 13 can also be a linear or branched C1-C3 alkoxy group.

[0110] According to an embodiment of the present invention, when Gr is a residue of formula (VII), I is an integer from 0 to 4.

[0111] According to an embodiment of the present invention, m is 1, n is an integer from 1 to 2, p is an integer from 2 to 3, and q is an integer from 1 to 15.

[0112] According to an embodiment of the present invention, when Gr is a residue of formula (IV), I is an integer from 0 to 12, and R7 is a hydrogen atom.

[0113] According to an embodiment of the present invention, when Gr is a residue of formula (VIII), I is an integer from 0 to 12, and R 14 is selected from a hydrogen atom, a linear or branched C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 10 alkylaryl group.

[0114] According to an embodiment of the present invention, any group represented by W, W' or W” as defined above may optionally be substituted by an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a benzyl group, an amino group, an alkylamino group, an arylamino group, a benzylamino group, an aminoaryl group, a hydroxyl group or a carboxyl group, preferably substituted by a hydroxyl group or a carboxyl group.

[0115] According to an embodiment of the present invention, the heteroaryl group is selected from pyridine, pyrimidine, pyrrole, imidazole, furan, thiophene, indole, quinoline and azulene.

[0116] According to an embodiment of the present invention, R2-R3 are independently selected from a hydrogen atom, a C1-C3 alkyl group, a linear or branched C2-C5 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 10 alkyl-aryl group, a linear or branched C7-C 10 alkenyl-aryl group, a linear or branched C7-C 10 alkynyl-aryl group, a heteroaryl group, and R1 and R4 are independently selected from -CO-NHW' and -CO-OW”.

[0117] According to an embodiment of the present invention, the pyrrole derivative useful in the present invention bears at least one group represented by the residues (IV) to (IX) as described above, preferably where m is 1, n is an integer from 1 to 2, p is an integer from 2 to 3, q is an integer from 1 to 15, R7-R 15 are independently selected from a hydrogen atom, a linear or branched C1-C3 alkyl group and a heteroaryl group, and R 11 -R 13 may also be a linear or branched C1-C3 alkoxy group.

[0118] The pyrrole derivative useful in the present invention can be prepared according to methods known in the art. Briefly, a suitable primary amine can be reacted with a suitable diketone having the following formula (A):

[0119]

[0120] wherein R1-R4 have the meanings as described above.

[0121] According to an embodiment of the present invention, suitable diketones are selected from 2,5 - hexanedione, 3,4 - dimethyl - 2,5 - hexanedione, 2,5 - heptanedione, 6 - methylheptane - 2,5 - dione, 2,5 - octanedione, 3,6 - octanedione, 2,7 - dimethyl - 3,6 - octanedione and 2,2 - dimethyl - 3,6 - octanedione, preferably 2,5 - hexanedione and 3,6 - octanedione.

[0122] According to an embodiment of the present invention, suitable primary amines have the following formula (B):

[0123] W - NH2 (B)

[0124] wherein W has the meaning as described above.

[0125] According to an embodiment of the present invention, W is selected from a hydrogen atom, a straight - chain or branched - chain C1 - C3 alkyl group, a heteroaryl group, an aryl group, a cyclohexyl group and a residue of formula (II) as described above, preferably at least one of M, Q and J is a residue of formula (III) as described above.

[0126] According to a preferred embodiment, suitable primary amines are selected from 2 - amino - 1,3 - propanediol (serine), 2 - aminoethanol, 2 - aminoacetic acid, 3 - (trimethoxysilyl) propan - 1 - amine, 3 - triethoxysilyl - propan - 1 - amine, N',N' - dimethylpropane - 1,3 - diamine, 2 - aminoethanethiol, 3 - (aminomethyl) - 3,5,5 - trimethylcyclohexylamine, hexamethylenediamine, 4,4' - methylenebis(cyclohexylamine) and 3 - (diethoxy(methoxy)silyl) propan - 1 - amine.

[0127] According to a specific embodiment, preferred examples of pyrrole derivatives useful in the present invention are:

[0128] 2 - (2,5 - dimethyl - 1H - pyrrol - 1 - yl) propane - 1,3 - diol (SP)

[0129]

[0130] 2,5 - dimethyl - 1 - (3 - (triethoxysilyl)propyl) - 1H - pyrrole (APTESP)

[0131]

[0132] 2 - (2,5 - dimethyl - 1H - pyrrol - 1 - yl) acetic acid (GlyP)

[0133]

[0134] 2 - pyrrol - 1 - yl - 1,3 - propanediol;

[0135] 2,5-Dimethyl-1-(3-(trimethoxysilyl)propyl)-1H-pyrrole (PPTMS);

[0136] O-(2-(2,5-Dimethyl-1H-pyrrol-1-yl)propyl)-O'-(2-methoxyethyl) polypropylene glycol (PPGP);

[0137] 2-(2,5-Dimethyl-1H-pyrrol-1-yl)ethane-1-thiol (SHP);

[0138] 1-(1,3-Dihydroxypropan-2-yl)-5-((1,3-dihydroxypropan-2-yl)carbamoyl)-1H-pyrrole-2-carboxylic acid;

[0139] 1-(1,2-Dihydroxypropan-3-yl)-5-((1,2-dihydroxypropan-3-yl)carbamoyl)-1H-pyrrole-2-carboxylic acid;

[0140] 1-(2-Hydroxyethyl)-5-((2-hydroxyethyl)carbamoyl)-1H-pyrrole-2-carboxylic acid;

[0141] 1-Benzyl-5-(benzylcarbamoyl)-1H-pyrrole-2-carboxylic acid;

[0142] 1-Octyl-5-(octylcarbamoyl)-1H-pyrrole-2-carboxylic acid;

[0143] 1-(1-Hydroxypropan-2-yl)-5-((1-hydroxypropan-2-yl)carbamoyl)-1H-pyrrole-2-carboxylic acid;

[0144] 1-(2-Mercaptoethyl)-5-((2-mercaptoethyl)carbamoyl)-1H-pyrrole-2-carboxylic acid;

[0145] 1-(3-(Triethoxysilyl)propyl)-5-((3-(triethoxysilyl)propyl)carbamoyl)-1H-pyrrole-2-carboxylic acid;

[0146] 1-(Carboxymethyl)-5-((carboxymethyl)carbamoyl)-1H-pyrrole-2-carboxylic acid; and

[0147] 1-(2-Aminoethyl)-5-((2-aminoethyl)carbamoyl)-1H-pyrrole-2-carboxylic acid.

[0148] Lignin

[0149] Lignin is a synthetic biopolymer in the plant world and is second only to cellulose in terms of production. Biomass formed by cellulose and lignin accounts for approximately 70% of the total biomass.

[0150] Lignin is a heavy and complex organic polymer mainly formed from phenolic compounds. In particular, lignin consists of cross-linked and three-dimensional polymer structures of phenylpropane units, especially phenylpropanols (coumaryl, coniferyl, and sinapyl). Alcohols are synthesized by plants through the enzyme cinnamoyl-CoA:NADPH oxidoreductase to reduce the corresponding acids.

[0151]

[0152] The components of lignin are present in different amounts depending on the type of plant in which it is formed. Coniferyl alcohol is the most abundant precursor of coniferous lignin. Lignin from woody angiosperms (broadleaves) is primarily derived from sinapyl alcohol. p-Coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol are all present in significant amounts in the composition of herbaceous plant lignin (mainly the grass family).

[0153] The polymer structure of lignin is very complex and has a three-dimensional form formed by cross-links that contain ether bonds (C-O-C), carbon bonds (C-C), and ester bonds (CO-O-C) in different phenylpropane units.

[0154] The main sources of lignin come from the paper industry and the biofuels production industry. In both cases, lignin represents a by-product that must be separated from the main product (cellulose or bioethanol). The unpurified crude lignin obtained from the separation process is usually burned to generate energy. The methods used to separate lignin from other plant components (cellulose and hemicellulose) produce different types of lignin.

[0155] Industrially, a distinction is mainly made between two types of native lignin: sulfonated lignin obtained by treatment methods including treatment with sulfate or sulfite (sulfate or kraft pulping, sulfite process, semi-chemical process), and sulfur-free lignin obtained by treatment methods including treatment with soda (soda pulping), with high-pressure steam (steam explosion), or with organic solvents (solvent pulping).

[0156] The "soda process" operates without using sulfur-containing chemicals. Only sodium hydroxide in water is used as the pulping reagent. To achieve a satisfactory delignification level, pulping is carried out at high temperatures (up to 210 °C), which results in a highly extended degradation of the polymeric sugars. The use of anthraquinone promotes lignin removal ("soda-anthraquinone technology") and makes the method industrially applicable.

[0157] Using a mixed sulfate (mainly Ca 2+ and Mg 2+)As an active component, the industrial production of the sulfite process has been achieved. By changing the counterion, this method can be carried out at different pH values, ranging from strongly acidic to strongly basic conditions. The classical method operates under strong (calcium) or medium (magnesium) acidic conditions. The sulfite component chemically modifies lignin and makes it water-soluble. Due to its significant ecological impact, this method has not been widely used. However, it is commonly applied in chemical pulp production because it can provide pulp that is easily bleached.

[0158] The kraft pulping method means treating the pulp with a mixture of sodium sulfate, sodium carbonate, sodium hydroxide, and sodium sulfide at elevated temperatures. Lignin is removed from the lignocellulosic material in the form of water-soluble alkali lignin dissolved in the black liquor. The lignin after kraft pulping contains at most 3% sulfur.

[0159] The "organic solvent" technique for lignin separation means adding an organic solvent to the pulping mixture to increase lignin solubility and facilitate subsequent bleaching. Water-miscible solvents such as methanol and ethanol are mainly used, so that the true chemicals (acids, bases, sulfites or sulfides, or oxidants) are still used as pulping agents. The "organic solvent" method is generally divided into acidic and basic methods. The extraction of lignin by the "organic solvent" method is described, for example, in US2010 / 159522, US2013 / 0005952, US2009 / 0062516, WO92 / 013849, WO2009 / 092749, WO2011 / 014894, WO2011 / 149341, WO2012 / 027767, and WO2015 / 075080.

[0160] The alkali metal salts of sulfonated lignin have a density of about 1.5 g / cm 3 while sulfur-free lignin has a density of about 1.3 g / cm 3 Therefore, the density of crude lignin is much lower than that of carbon black.

[0161] Preferably, the lignin is selected from softwood kraft lignin, hardwood kraft lignin, soda straw lignin, wheat straw lignin, rice husk lignin, lignin obtained by a biorefinery process, and organic solvent lignin.

[0162] Adducts between lignin and pyrrole derivatives

[0163] According to the present invention, an adduct between lignin and a pyrrole derivative is obtained by forming covalent and non-covalent bonds.

[0164] From the chemical structure of the basic components of lignin, it can be easily deduced that the latter is particularly rich in hydroxyl groups (-OH), mainly phenolic or alcoholic, and to a lesser extent carboxylic, which makes lignin particularly suitable for functionalization by esterification reactions.

[0165] In the esterification reaction, the hydroxyl groups of lignin react with pyrrole derivatives containing a carboxyl or acyl group (such as acyl halides like acetyl chloride or acid anhydrides like acetic anhydride) to form the corresponding esters. The esterification reaction involves all the hydroxyl groups of phenols and alcohols. The esterification reaction is typically carried out under heating, preferably under reflux conditions, in a suitable solvent using techniques well-known to those skilled in the art. This reaction can be carried out in the presence of a basic catalyst or an acidic catalyst (such as sulfuric acid).

[0166] The hydroxyl groups of lignin also allow for reaction with pyrrole derivatives containing an alkoxysilyl group, such as 2,5-dimethyl-1-(3-(triethoxysilyl)propyl)-1H-pyrrole and 2,5-dimethyl-1-(3-(trimethoxysilyl)propyl)-1H-pyrrole. This reaction is typically carried out under heating in a suitable solvent using techniques well-known to those skilled in the art.

[0167] On the other hand, the presence of phenolic groups enables lignin to undergo the Reimer-Tiemann reaction, thereby obtaining formylated lignin with aldehyde groups (-HC=O), which allows for functionalization by forming acetals or hemiacetals. In this case, the formylated lignin reacts with pyrrole derivatives containing one or more hydroxyl groups. This reaction is typically carried out under heating, preferably under reflux conditions, in a suitable solvent, using techniques well-known to those skilled in the art. This reaction can be carried out in the presence of a basic catalyst or an acidic catalyst (such as sulfuric acid).

[0168] In addition, the presence of ionic and non-ionic groups, such as hydroxyl, carboxyl, amide, and amino groups, in both lignin and pyrrole derivatives allows for the formation of several additional non-covalent bonds derived from intermolecular interactions, such as ionic bonds, van der Waals forces, ion-dipole interactions, and hydrogen bonds. Such non-covalent bonds contribute to a lesser extent to the binding of lignin and pyrrole derivatives and to the formation of adducts as defined herein.

[0169] According to a preferred embodiment, the adduct between lignin and pyrrole derivatives is present in the elastomer composition in an amount equal to or higher than about 5 phr, preferably higher than about 10 phr. Preferably, the adduct between lignin and pyrrole derivatives is present in the elastomer composition in an amount lower than about 75 phr, preferably lower than about 50 phr.

[0170] Diene elastomer polymer

[0171] The diene elastomer polymers for use in the present invention may be selected from those commonly used in sulfur-crosslinkable elastomeric materials, which are particularly suitable for the production of tires, i.e., elastomer polymers or copolymers having unsaturated chains, characterized in that the glass transition temperature (Tg) is generally below 20 °C, preferably in the range of 0 °C to -110 °C. 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 dienes optionally mixed with at least one comonomer selected from mono-vinyl aromatic hydrocarbons and / or polar comonomers.

[0172] The conjugated dienes generally contain 4 to 12, preferably 4 to 8 carbon atoms and may be selected, for example, from: 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 or mixtures thereof. 1,3-Butadiene and isoprene are particularly preferred.

[0173] The mono-vinyl aromatic hydrocarbons which may optionally be used as comonomers generally contain 8 to 20, preferably 8 to 12 carbon atoms and may be selected, for example, from: styrene; 1-vinylnaphthalene; 2-vinylnaphthalene; various alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl derivatives of styrene, such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-p-tolylstyrene, 4-(4-phenylbutyl)styrene or mixtures thereof. Styrene is particularly preferred.

[0174] The polar comonomers which may optionally be used may be selected, for example, from: vinylpyridine, vinylquinoline, acrylic acid and alkyl acrylates, nitriles or mixtures thereof, such as, for example, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile or mixtures thereof.

[0175] Preferably, the diene elastomer polymers useful in the present invention may be selected, for example, from: cis-1,4-polyisoprene (natural or synthetic, preferably natural rubber), 3,4-polyisoprene, polybutadiene (especially polybutadiene having 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 or mixtures thereof.

[0176] It is also possible to use diene elastomer polymers functionalized by reaction with a suitable terminating agent or coupling agent. In particular, diene elastomer polymers obtained by anionic polymerization in the presence of an organometallic initiator (especially 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 imine, carbodiimide, alkyltin halide, substituted benzophenone, alkoxysilane or aryloxysilane).

[0177] Carbon black

[0178] According to a preferred embodiment, the carbon black reinforcing filler useful in the present invention may be selected from those having a surface area of not less than 20 m 2 / g (which is determined by STSA - statistical thickness surface area - according to ISO 18852:2005).

[0179] According to a preferred embodiment, the carbon black reinforcing filler is present in the elastomer composition in an amount greater than about 15 phr, preferably greater than about 20 phr. Preferably, the carbon black reinforcing filler is present in the elastomer composition in an amount less than about 80 phr, preferably less than about 60 phr.

[0180] Additional reinforcing fillers

[0181] At least one additional reinforcing filler can be advantageously added to the above elastomer composition, usually in an amount of 1 phr to 70 phr, preferably about 10 phr to about 60 phr. The additional reinforcing filler can be selected from those commonly used in crosslinked products, especially for tires, such as silica, silicate, alumina, aluminosilicate, such as sepiolite, palygorskite (also known as attapulgite), montmorillonite, halloysite, etc. (which may be modified and / or derivatized by acid treatment), calcium carbonate, kaolin or mixtures thereof.

[0182] The silica useful in the present invention generally has a BET surface area (measured according to the ISO 5794 / 1 standard) of about 50 m 2 / g to about 500 m 2 / g, preferably about 70 m 2 / g to about 200 m 2 / g of pyrogenic silica or preferably precipitated silica.

[0183] Examples of silica reinforcing fillers useful in the present invention and commercially available are those named Hi - 190, Hi - 210, Hi - 233, Hi - Known products are available from PPG Industries (Pittsburgh, Pa.); or products named VN2, VN3, product 7000 from Evonik; or products named 1165MP and 1115MP from Solvay.

[0184] According to one embodiment, the elastomeric composition may comprise a silane coupling agent capable of interacting with silica and / or silicate that may be present as reinforcing fillers and bonding them to the diene elastomeric polymer during vulcanization.

[0185] According to one embodiment, the silane coupling agent useful in the present invention may be selected from those having at least one hydrolyzable silyl group, which may be represented, for example, by the following general formula (II):

[0186] (R)3Si-C n H 2n -X(II)

[0187] where the R groups may be the same or different and are selected from: alkyl, alkoxy or aryloxy, or from halogen atoms, provided that at least one R group is alkoxy or aryloxy; n is an integer from 1 to 6, including 1 and 6; X is a group selected from the following: nitroso, mercapto, amino, epoxide, vinyl, imide, chlorine, -(S) m C n H 2n -Si-(R)3 and -S-COR, where m and n are integers from 1 to 6, including the end values, and the R groups are as defined above.

[0188] According to one embodiment, the silane coupling agent may be present in the elastomeric composition in an amount ranging from 0.01 phr to about 10 phr, preferably from about 0.5 phr to about 5 phr.

[0189] Vulcanizing agent

[0190] The elastomeric composition can be vulcanized according to known techniques, in particular using a sulfur-based vulcanization system commonly used for diene elastomeric polymers. For this purpose, a sulfur-based vulcanizing agent is incorporated together with a vulcanization accelerator into the elastomeric stock obtained from the elastomeric composition after one or more thermomechanical treatment steps. In the final treatment step, the temperature is generally kept below 120 °C, preferably below 100 °C, to prevent any unwanted pre-crosslinking phenomenon.

[0191] Preferably, the vulcanizing agent comprises a sulfur-based vulcanization system, which includes sulfur or sulfur-containing molecules (sulfur donors) and vulcanization accelerators and / or activators known in the art.

[0192] Particularly effective activators are zinc compounds, especially ZnO, ZnCO3, zinc salts of saturated or unsaturated fatty acids containing 8 to 18 carbon atoms, such as zinc stearate, which is preferably formed in situ from ZnO and fatty acids in the elastomer composition, or mixtures thereof.

[0193] Commonly used accelerators can be selected from: dithiocarbamates, guanidines, thioureas, thiazoles, sulfenamides, thiurams, amines, xanthates or mixtures thereof.

[0194] According to a preferred embodiment, the crosslinkable elastomer composition comprises a vulcanizing agent in an amount equal to or greater than about 1 phr, preferably equal to or greater than about 2 phr.

[0195] Preferably, the amount of the vulcanizing agent is less than or equal to about 7.5 phr, preferably less than or equal to about 7 phr.

[0196] Advantageously, the amount of sulfur is from about 2 phr to about 6.5 phr.

[0197] Other additives

[0198] The elastomer composition according to the present invention may comprise other common additives selected based on the specific application intended for the composition. For example, the material can be mixed with: antioxidants, anti-aging agents, plasticizers, binders, anti-ozonants, modified resins or mixtures thereof.

[0199] In particular, to improve processability, the vulcanizable elastomer composition can be mixed with a plasticizer, which is generally selected from mineral oils, vegetable oils, synthetic oils or mixtures thereof, such as aromatic oils, naphthenic oils, phthalates, soybean oil or mixtures thereof. The amount of the plasticizer generally ranges from 0 phr to about 70 phr, preferably about 5 phr to about 30 phr.

[0200] Preparation of elastomer composition

[0201] The elastomer composition can be prepared by mixing a necessary amount of a diene elastomer polymer with a lignin adduct, a reinforcing filler, a vulcanizing agent and any other additives that may be present according to techniques known in the industry.

[0202] Mixing can be carried out, for example, using at least one batch mixer and / or at least one continuous mixer.

[0203] In the context of the present specification and the following claims, the term "batch mixer (or mixing device)" denotes a mixing device which is configured to periodically supply, in predetermined amounts, the various components of the material to be prepared and to mix them for a predetermined time to obtain a batch of said material.

[0204] At the end of the mixing step, the entire batch of material obtained is completely discharged from the mixing device as a single solution. Examples of batch mixers are internal mixers of the tangential rotor or of the interpenetrating rotor type.

[0205] In the context of the present specification and the appended claims, the term "continuous mixer (or mixing device)" denotes a mixing device which is configured to continuously feed, generally by means of a controlled dosing dispenser, the components of the material to be prepared, to mix the components in order to produce the material and to discharge it in a continuous flow (except for possible stoppages of the mixing device due to maintenance or changes in the material formulation).

[0206] In the terminology of the elastomer mixing machine field, continuous mixing devices are sometimes referred to as: "mixing extruders", which are considered herein to be equivalent to "continuous mixers".

[0207] Then, a continuous mixer (in particular its active elements, such as screws or mixer satellites) is provided with mixing sections and conveying sections alternating with the mixing sections, the mixing sections being capable of applying a high shear stress to the material being mixed, the conveying sections being capable of applying a thrust to the material being processed to feed it from one longitudinal end of the internal chamber to the other longitudinal end. It may also be provided with possible redistribution sections.

[0208] Examples of continuous mixing devices are twin-screw or multi-screw mixers (such as toroidal mixers), co-penetrating and co-rotating or planetary mixing devices.

[0209] Both batch mixers and continuous mixers are capable of imparting sufficient energy to the materials produced with them to mix and uniformly disperse the various components, even in the case of cold feeding of the components, and in the case of materials containing elastomeric components, of masticating the elastomeric compound, raising its temperature so that it is processable and plastic, thus facilitating the incorporation and / or distribution of the components within the elastomeric polymer matrix.

[0210] The elastomeric compound thus obtained can then be stored or directly sent to the subsequent production steps of the tyre according to the invention.

[0211] Tire

[0212] According to one embodiment, a tyre for a vehicle wheel according to the invention comprises:

[0213] - A carcass structure, said carcass structure comprising at least a carcass ply, said carcass ply having opposite lateral edges associated with respective bead structures;

[0214] - Optionally, a belt structure applied in a radially outer position relative to said carcass structure;

[0215] - A tread applied in a radially outer position to said carcass structure and said belt structure (if present), and

[0216] - Optionally, an underlayer and / or wear-resistant elongate member and / or sidewall and / or sidewall insert and / or mini-sidewall and / or underliner and / or skim coat and / or chafing strip and / or bead filler and / or sheet.

[0217] According to one embodiment, the structural components according to the present invention are selected from a carcass structure, a belt structure, additional belt layers, a skim coat, a sidewall, a sidewall insert, a wear-resistant layer, a bead filler, a bead reinforcement layer (bead filler and chafing strip) and a tread (single structure or cap base structure).

[0218] According to a preferred embodiment, the structural component is an additional belt layer. The additional belt layer is commonly referred to as a "zero-degree belt".

[0219] The carcass structure is intended to impart the required structural integrity and strength characteristics to the tire, while the belt structure is also intended to transfer the lateral and longitudinal stresses to which the running tire is subjected due to contact with the road surface to the carcass structure, so as to impart the required grip, driving stability, controllability, directionality, road grip and comfort. The zero-degree reinforcement layer (when present) alternatively is intended to limit the radial elongation of the belt structure.

[0220] Preferably, the structural component is a carcass structure including a plurality of reinforcing elements. Preferably, the carcass structure is a radial carcass structure. Preferably, a plurality of reinforcing elements are incorporated within two carcass plies radially superposed on one another.

[0221] Preferably, the belt structure includes at least one reinforcing element wound around the carcass structure in a substantially circumferential winding direction.

[0222] In one embodiment, at least one bead reinforcement layer can be associated with the carcass layer at or near the respective anchoring structure.

[0223] Preferably, said at least one bead reinforcement layer includes at least one reinforcing element.

[0224] Said at least one bead reinforcement layer can be interposed between the respective turned-up end flaps of said at least one carcass layer and the respective anchoring structure.

[0225] More preferably, the at least one bead reinforcement layer may at least partially surround the anchoring structure or the bead. This bead reinforcement is also referred to by the term "outer chafe strip".

[0226] The sidewall reinforcement layer may be associated with the respective turned-up end flaps of at least one carcass ply in the axially outermost position relative to the respective annular anchoring structure.

[0227] More preferably, the at least one sidewall reinforcement layer may extend from the carcass structure along the sidewall towards the crown. Such a sidewall reinforcement layer is also referred to by the term "bead chafe strip".

[0228] In a preferred embodiment, the structural components according to the invention are selected from a carcass structure, a belt structure, an outer chafe strip, a bead chafe strip and a coated ply.

[0229] The tire according to the invention can be used on two-wheeled, three-wheeled or four-wheeled vehicles. The tire according to the invention can be used for summer or winter use or for all seasons.

[0230] The tire according to the invention can be a tire for passenger cars, including automotive tires (e.g. high-performance tires) and tires for light transport vehicles (e.g. vans, campers, pick-up trucks), which usually have a total mass when fully loaded equal to or less than 3500 kg.

[0231] The tire according to the invention can be a tire for motorcycles, such as motorcycles belonging to the categories of scooters, scramblers, customs, supersport, superbike and sport touring. The term "tire for motorcycle wheels" means a tire having a high curvature ratio (usually greater than 0.200), which is capable of reaching a high lean angle (bank angle) during motorcycle cornering.

[0232] The tire according to the invention can be a tire for bicycle wheels, such as wheels for racing bikes, mountain bikes and city bikes. Racing bikes include high-performance bikes for road or track races, such as recumbent bikes, time trial bikes, triathlon bikes and / or so-called fitness bikes. Mountain bikes include bikes for uneven or irregular terrain, such as muddy, sandy, rocky, compacted, soft ground, etc., and in particular include mountain bikes (MTB) or all-terrain bikes (ATB) (usually divided into cross-country (XC), marathon, track, all-mountain, endurance, freeride and downhill categories). City bikes include bikes mainly for urban use on asphalt roads or bike paths, such as urban bikes, city bikes, commuter bikes and touring bikes.

[0233] Drawings

[0234] The description is given below with reference to the accompanying drawings, which are provided for illustrative purposes only and are thus non-limiting, wherein:

[0235] - Figure 1 A semi-sectional view of a tire for a vehicle wheel according to the invention is schematically shown.

[0236] - Figure 2 The FT-IR (ATR) spectra of formylated lignin (curve B) and formylated lignin / SP adduct (curve A) of Example 10 are shown.

[0237] - Figure 3 The FT-IR (ATR) spectra of lignin (curve B) and lignin / APTESP adduct (curve A) of Example 11 are shown.

[0238] - Figure 4 The FT-IR (ATR) spectra of lignin (curve B) and lignin / GlyP adduct (curve A) of Example 12 are shown. DETAILED DESCRIPTION OF THE INVENTION

[0240] The present invention will be described in more detail with reference to the attached Figure 1 , by way of illustrative embodiments, where "a" represents the axial direction and "r" represents the radial direction. For simplicity, Figure 1 only a part of the tire is shown, and the remaining parts not shown are identical and symmetrically arranged with respect to the radial direction "r".

[0241] Reference numeral 100 denotes in Figure 1 a tire for a vehicle wheel, which generally comprises a carcass structure 101 having respectively opposite end flaps that engage with corresponding annular anchoring structures 102 (referred to as bead cores), possibly associated with bead fillers 104. The tire area including the bead cores 102 and the bead fillers 104 forms a bead structure 103 intended for anchoring the tire to a corresponding mounting rim (not shown). Each bead structure 103 is associated with the carcass structure by folding the opposite lateral edges of at least one carcass ply 101 around the bead core 102 backwards so as to form the so-called carcass flaps 101a as Figure 1 shown.

[0242] The carcass structure 101 may be associated with a belt structure 106, which includes one or more belt layers 106a, 106b that are placed radially superimposed relative to each other and relative to the carcass structure 101 and typically have metal reinforcing cords. Such reinforcing cords may have a cross orientation relative to the circumferential extension direction of the tire 100. The "circumferential" direction refers to the direction that generally faces the direction of rotation of the tire, or in any case a direction that is slightly inclined relative to the direction of rotation of the tire.

[0243] The belt structure 106 further includes at least one radially external reinforcing layer 106c relative to the belt layers 106a, 106b. The radially external reinforcing layer 106c includes a fabric or metal cord that is arranged at an angle that is substantially zero relative to the circumferential extension direction of the tire and is immersed in an elastomeric material. Preferably, the cords are substantially parallel and arranged side by side to form a plurality of turns. Such turns are generally oriented according to the circumferential direction (usually having an angle between 0° and 5°), and with respect to their laying relative to the equatorial plane X-X of the tire, this orientation is generally referred to as "zero degree". The "equatorial plane" of the tire refers to the plane that is perpendicular to the axis of rotation of the tire and divides the tire into two symmetrically equal parts.

[0244] The crown 109 of the vulcanized elastomeric compound is applied in a radially inner position relative to the carcass structure 101 and / or, if present (as in the case shown), relative to the belt structure 106.

[0245] In the radially outer position, the crown 109 has a rolling part 109a that is intended to contact the ground. A circumferential groove is formed by transverse notches ( Figure 1 not shown in the figure) to define a plurality of blocks of various shapes and sizes distributed in the rolling part 109a, which is generally manufactured in this part 109a and, for simplicity, is shown as smooth in Figure 1 the figure.

[0246] To optimize the performance of the tread, the crown can be made into a two-layer structure.

[0247] This two-layer structure includes a rolling layer or part 109a (referred to as the cap) and a substrate 111 (referred to as the base) that form a so-called cap-base structure. Thus, an elastomeric material that can provide low rolling resistance for the cap 109a and at the same time provide high wear resistance and crack resistance can be used, while the elastomeric material of the substrate 111 can be specifically targeted at low hysteresis to cooperate in reducing the rolling resistance. The bottom layer 111 of the vulcanized elastomeric compound can be provided between the belt structure 106 and the rolling part 109a.

[0248] In addition, the corresponding sidewalls 108 of the vulcanized elastomeric compound are further applied to the carcass structure 101 in an axially outer position, each sidewall extending from one of the lateral edges of the crown 109 until the corresponding bead structure 103.

[0249] Optionally, a strip composed of an elastomeric compound 110 (commonly referred to as a "mini-sidewall") consisting of a vulcanized elastomeric compound may be provided in the connection region between the sidewall 108 and the crown 109. The mini-sidewall is typically obtained by co-extrusion with the crown 109 and allows for improved mechanical interaction between the crown 109 and the sidewall 108. Preferably, the end of the sidewall 108 directly covers the lateral edge of the crown 109.

[0250] In some specific embodiments, such as the embodiments shown and described herein, the stiffness of the bead 103 can be improved by providing a reinforcing layer 120 commonly referred to as an "outer chafe ply" in the tire bead.

[0251] The outer chafe ply 120 is wound around the corresponding bead core 102 and bead filler 104 so as to at least partially surround them. The outer chafe ply 120 is disposed between the carcass ply 101 and the bead structure 103. Generally, the outer chafe ply 120 contacts the carcass ply 101 and the bead structure 103. The outer chafe ply 120 typically includes a plurality of metal or fabric cords incorporated in a vulcanized elastomeric compound.

[0252] In some specific embodiments, for example, the embodiments shown and described herein, the bead structure 103 may further include an additional reinforcing layer 121, which is commonly referred to by the term "bead chafe ply" and has the function of increasing the rigidity and integrity of the bead structure 103.

[0253] The bead chafe ply 121 typically includes a plurality of cords incorporated in a vulcanized elastomeric compound; such cords are typically made of textile materials (such as aramid or rayon) or metal materials (such as steel cords).

[0254] Optionally, a wear-resistant strip 105 is provided so as to wrap around the bead structure 103 along the axially inner and outer and radially inner regions of the bead structure 103, such that when the tire 100 is mounted on a rim, it inserts itself between the bead structure 103 and the wheel rim.

[0255] In addition, the radially inner surface of the tire 100 is preferably lined with a layer of substantially airtight elastomeric material or a so-called liner 112.

[0256] According to an embodiment not shown, the tire can be a tire for a motorcycle wheel. The profile of the straight portion of a tire (not shown) for a motorcycle has a high lateral curvature because it must ensure a sufficient contact area under all leaning conditions of the motorcycle. The lateral curvature is defined by the ratio between the distance f of the ridges of the tread, measured in the equatorial plane of the tire, from a line passing through the laterally opposite ends of the tread itself, and the width C defined by the distance between the laterally opposite ends of the tread itself. A tire with a high lateral curvature means a tire with a lateral curvature ratio (f / C) of at least 0.20.

[0257] The belt structure 106, and / or the carcass structure 101, and / or the bead structure 103, such as the outer chafer 120 and / or the bead chafer 121, can advantageously be made of an elastomeric composition comprising an adduct between lignin and a pyrrole derivative according to the present invention, because the lower hysteresis means (i) a lower dissipation of energy in the form of heat during driving, thus preventing the onset of excessive operating temperatures that could endanger the integrity of the tire, and (ii) lower fuel consumption.

[0258] The construction of the tire 100 as described above is carried out by assembling the respective semi-finished products onto a forming drum (not shown) by means of at least one assembling device.

[0259] On the forming drum, at least a part of the assembly intended to form the carcass structure 101 of the tire 100 is constructed and / or assembled. More specifically, the forming drum is intended to first receive a possible liner 112 and then the carcass ply 101. Thereafter, a device (not shown) coaxially engages one of the annular anchoring structures 102 around each end flap, positions an outer sleeve comprising the belt structure 106 and the crown 109 in a coaxial centered position around the cylindrical carcass sleeve, and shapes the carcass sleeve according to an annular configuration by radial expansion of the carcass ply 101 so as to apply it against the radially inner surface of the outer sleeve.

[0260] After the construction of the green tire 100, a molding and vulcanization treatment is generally carried out in order to determine the structural stability of the tire 100 by vulcanization of the elastomeric compound, as well as to confer the desired tread pattern on the crown 109 and any distinctive graphic symbols at the sidewall 108.

[0261] The present invention will be further illustrated by a number of preparation examples hereinafter, which are for illustrative purposes only and not any limitation of the present invention. Examples

[0262] Characterization methods

[0263] Elemental analysis

[0264] Elemental analysis was performed using an Elementary Analyze Cos tech ECS model 4010.

[0265] FT-IR analysis

[0266] Using a self-supporting silica disc made of potassium bromide and a small amount of sample, the infrared spectrum was recorded in transmission mode (128 scans and 4 cm -1 resolution). The infrared spectrum disc was obtained from a disc machine by increasing the pressure. Bulk measurements were carried out using a Thermo Electron Continuum Infrared Microscope coupled with an FT-IR Nicolet Nexus spectrometer.

[0267] 1 H-NMR analysis

[0268] The NMR spectrum was recorded on a Bruker AV 400 (400 MHz).

[0269] Tollens' reagent

[0270] Tollens' reagent is a colorless basic aqueous solution containing silver ions coordinated with ammonia [Ag(NH3) 2+ . It is prepared using a two-step procedure:

[0271] - Step 1: Mix an aqueous solution of silver nitrate with an aqueous solution of sodium hydroxide, resulting in the formation of silver hydroxide, which then dissociates to give silver oxide;

[0272] - Step 2: Add ammonia water dropwise until the precipitated silver oxide is completely dissolved.

[0273] MDR rheological analysis

[0274] Using the following procedure, MDR rheological analysis was carried out using a Monsanto R.P.A.2000 rheometer with a sulfur-based system: 5.0 g of green stock was added to the RPA at 50 °C for 1 minute, and the first strain sweep test (low deformation, 0.1 - 25% strain) was carried out at 50 °C. Then the sample was crosslinked at 170 °C for 10 minutes at a frequency of 1.7 Hz and an oscillation angle of 6.98% (0.5 radian).

[0275] The following parameters were obtained: minimum torque (M L ), maximum torque (M H ), induction time (t S1 ), and time to reach the optimum vulcanization level (t 90 ), cure rate. The cure rate was calculated using the following equation:

[0276]

[0277] Dynamic-mechanical analysis in shear mode. Strain sweep test

[0278] Using the following procedure, the storage modulus G', loss modulus G", and Tanδ were measured using a rheometer Monsanto R.P.A. 2000: 5.0 g of the green stock compound was added to the RPA at 50 °C for 1 minute and the first strain sweep test (low deformation, 0.1 - 25% strain) was carried out at 50 °C. Then the sample was crosslinked at 170 °C for 10 minutes at a frequency of 1.7 Hz and an oscillation angle of 6.98% (0.5 rad). After vulcanization, the sample was held at 50 °C for 20 minutes. At 50 °C and a frequency of 1 Hz, the final values of G', G", and Tanδ were obtained with a strain sweep test at low deformation (0.1 - 25% strain).

[0279] Dynamic-mechanical analysis in axial mode

[0280] According to the following method, the dynamic mechanical properties, storage modulus E', loss modulus E", and Tanδ in the axial mode were measured using an Instron dynamic device in tension-compression mode. During the entire test, the cylindrical (length = 25 mm; diameter = 12 mm) crosslinked elastomer was held at a predetermined temperature of 10 °C, 23 °C, and 70 °C. The sample was initially pre-compressed to a longitudinal deformation of 25% relative to the initial length and then subjected to a dynamic sinusoidal strain with an amplitude of ±3.5% relative to the initial length. The frequency used was 100 Hz. The properties measured were the dynamic storage modulus (E'), the dynamic loss modulus (E"), and thus the tanδ (loss factor) through the ratio of the two moduli (E" / E'). For the frequency used (100 Hz), each modulus was plotted against temperature to observe the effect of temperature on the dynamic mechanical properties in each sample.

[0281] Tensile test

[0282] According to ISO 37 standard, at 23 °C, a tensile strength test was carried out on each sample using a Zwick Roell Z010. The tensile test is a destructive test process that provides information about the tensile strength, yield strength, and ductility of the material. It measures the force required to break the sample and the extent to which the sample is stretched or elongated to that breaking point. Tensile measurements were determined on samples of elastomer compounds vulcanized at 170 °C for 10 minutes. Three replicate samples of each rubber compound were prepared and tested to reduce any type of error.

[0283] Through this test, the stress at elongation rates of 50% (Ca0.5), 100% (Ca1), 200% (Ca2), and 300% (Ca3), as well as the breaking stress (CR) and breaking elongation (AR) were evaluated.

[0284] Synthesis of Pyrrole Derivatives

[0285] Example 1

[0286] Synthesis of 2-(2,5-Dimethyl-1H-pyrrol-1-yl)propane-1,3-diol (SP)

[0287]

[0288] A mixture of 2,5-hexanedione (8.10 g, 0.0709 mol) and 2-aminopropane-1,3-diol (6.46 g, 0.0709 mol) was poured into a 100 mL round-bottom flask equipped with a magnetic stirrer. The mixture was then stirred at 150 °C (300 rpm) for 4 hours. The reaction mixture was then cooled to room temperature. 11.76 g of a pure dark amber viscous product was obtained. 1 1H NMR (CDCl3, 400 MHz); δ (ppm) = 2.27 (s, 6H); 3.99 (m, 4H); 4.42 (quintet, 1H); 5.79 (s, 2H). 13 13C NMR (DMSO-6, 100 MHz); δ (ppm) = 127.7; 105.9; 71.6; 61.2; 13.9.

[0289] Example 2

[0290] Synthesis of 2,5-Dimethyl-1-(3-(triethoxysilyl)propyl)-1H-pyrrole (APTESP)

[0291]

[0292] 3.76 g of 3-(triethoxysilyl)propan-1-amine (0.017 mol) and 1.94 g of 2,5-hexanedione (0.017 mol) were poured into a 250 mL round-bottom flask equipped with a magnetic stirrer. The mixture was then stirred at 155 °C (300 rpm) for 4 hours with a reflux condenser installed, and then stirred for an additional 30 minutes without the reflux condenser. The reaction mixture was then cooled to room temperature. 1 1H NMR (CDCl3, 400 MHz); δ (ppm) = 5.73 (s, 2H, CH), 3.80 (m, 6H, O-CH2), 3.70 (m, 2H, N-CH2), 2.20 (s, 6H, CH3), 1.71 (m, 2H, CH2), 1.22 (m, 2H, CH2), 0.62 (m, 3H, CH3). 1313C-NMR (CDCl3, 100 MHz); δ (ppm) = 127.6, 105.6, 56.1, 51.05, 27.01, 19.2, 13.01, 12.51.

[0293] Example 3

[0294] Synthesis of 2-(2,5-dimethyl-1H-pyrrol-1-yl)acetic acid (GlyP)

[0295]

[0296] 1 g of glycine (0.013 mol) and 1.52 g of 2,5-hexanedione (0.013 mol) were poured into a 50 mL round-bottom flask equipped with a magnetic stirrer. The mixture was stirred at 75 °C for 2 hours. Thereafter, the reaction mixture was cooled to room temperature.

[0297] 1 1H NMR (CDCl3, 400 MHz); δ (ppm) = 9.68 (1H, COOH), 5.76 (s, 2H, CH), 4.47 (s, 2H, CH2), 2.14 (s, 6H, CH3). 13 13C NMR (CDCl3, 100 MHz); δ (ppm) = 173.16, 128.02, 105.50, 45.20, 12.28.

[0298] Example 4

[0299] Synthesis of 2-pyrrol-1-yl-1,3-propanediol

[0300] In a 100 mL flask equipped with a neck with a magnetic reflux stirrer, 1.32 g of 2,5-dimethoxytetrahydrofuran (10 mmol), 1 g of serine alcohol (11 mmol) and 50 mL of HCl 0.1 N (5 mmol) were measured under reflux overnight. At the end of the reaction, the pH of the solution was neutralized by adding NaHCO3 and the solvent was removed from the reaction mixture on a rotary evaporator. The residue was thus dissolved several times in ethyl acetate to extract the reaction product. After weighing, the yield was estimated to be equal to 92% taking into account the purity of the composition detected by NMR.

[0301] Example 5

[0302] Synthesis of 2,5-dimethyl-1-(3-(trimethoxysilyl)propyl)-1H-pyrrole (PPTMS)

[0303] Into a 100-mL single-necked flask equipped with a magnetic stirrer, 1 g (5.58 mmol) of 3-(trimethoxysilyl)propan-1-amine and 0.640 g (5.58 mmol) of 2,5-hexanedione were charged. The mixture was stirred at 150 °C for 6 hours. The product was isolated as a thick pale yellow viscous solid and analyzed by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). GC-MS analysis showed the compound 2,5-dimethyl-1-(3-(trimethoxysilyl)propyl)-1H-pyrrole and the unreacted 3-(trimethoxysilyl)propan-1-amine. The yellow solid was then dissolved in dichloromethane. The resulting solution was washed with deionized water. The organic phase was dried over Na2SO4 and dried thoroughly under reduced pressure. The isolated solid was the pure compound 2,5-dimethyl-1-(3-(trimethoxysilyl)propyl)-1H-pyrrole. The weight of this compound allowed us to calculate a yield equal to 89%.

[0304] Example 6

[0305] Synthesis of O-(2-(2,5-dimethyl-1H-pyrrol-1-yl)propyl)-O'-(2-methoxyethyl) polypropylene glycol (PPGP)

[0306] Into a 100-mL single-necked flask equipped with a magnetic stirrer, 1 g (1.6 mmol) of O-(2-aminopropyl)-O'-(2-methoxyethyl) polypropylene glycol (Mn = 600) and 0.190 g (1.6 mmol) of 2,5-hexanedione were charged. The mixture was stirred at 150 °C for 6 hours. The product was isolated as a very viscous amber liquid and analyzed by nuclear magnetic resonance (NMR), which showed only the expected compound O-(2-(2,5-dimethylpyrrol-1-yl)propyl)-O'-(2-methoxyethyl) polypropylene glycol. The weight measured by NMR analysis and the observed chemical purity allowed the assessment of a yield equal to 97%.

[0307] Example 7

[0308] Synthesis of 2-(2,5-dimethyl-1H-pyrrol-1-yl)ethane-1-thiol (SHP)

[0309] Under a constant N2 flow, 2.93 g (0.02577 mol) of 2-aminoethanethiol hydrochloride was introduced into a 50 mL round-bottomed double-necked flask pre-dried in an oven, and the system was brought to 50 °C with stirring (300 rpm) until complete dissolution.

[0310] Then the mixture was brought back to room temperature, and under a stream of N2, 2.93 g (0.02577 mol) of 2,5 - hexanedione was injected into the flask. The mixture was stirred (300 rpm) at room temperature for 12 h. Then, 1.5 g of 2 - aminoethanethiol hydrochloride was added, the temperature was raised to 50 °C, and the mixture was stirred for 1 h. The pure product was obtained by washing with water (3 × 10 mL). 3.1 g of the product was obtained (yield = 77.5%).

[0311] 1 1H NMR (D2O, 400 MHz); δ (ppm) = 2.05 (s, 6H); 2.9 (m, 4H); 3.33 (t, 1H); 3.43 (t, 1H); 5.42 (s, 2H).

[0312] Example 8

[0313] Synthesis of 1 - (1,3 - dihydroxypropan - 2 - yl) - 5 - ((1,3 - dihydroxypropan - 2 - yl)carbamoyl) - 1H - pyrrole - 2 - carboxylic acid

[0314] 3 - Hydroxy - 2 - oxo - 2H - pyran - 6 - carboxylic acid (135 mg, 0.87 mmol) and serine alcohol (2 - amino - 1,3 - propanediol, 455 mg, 4.87 mmol) were charged into a 25 mL round - bottom flask. The heterogeneous system was heated at 60 °C, then closed and kept at this temperature with stirring until the reaction was complete, which was corroborated by 1 H - NMR and 13 C - NMR analysis of the reaction mixture samples. Then 1 - (1,3 - dihydroxypropan - 2 - yl) - 5 - ((1,3 - dihydroxypropan - 2 - yl)carbamoyl) - 1H - pyrrole - 2 - carboxylic acid (Compound 1) was separated by column chromatography (75% yield).

[0315] Synthesis of formylated lignin

[0316] Example 9

[0317] Lignin formylation reaction by the Reimer - Tiemann reaction

[0318] At room temperature, 10 g of lignin and 4.73 g of potassium hydroxide were placed in a 250 ml flask and stirred until a homogeneous slurry mixture was obtained. A small amount of deionized water was added to make the mixture less viscous. Chloroform was added to the mixture, the reaction system was closed and stirred for 2 h. Then deionized water was added, and the pH of the solution was adjusted to 7 with acetic acid to promote the precipitation of formylated lignin. The solution was filtered to recover formylated lignin, which was then washed with a large amount of deionized water to remove reagent residues. The formylated lignin was dried at room temperature for 48 h.

[0319] Characterization of Formylated Lignin

[0320] Lignin was oximated to quantitatively evaluate the carbonyl groups present in both lignin and formylated lignin.

[0321] An excess of hydroxylamine hydrochloride and triethanolamine (TEA) was used as the oximation mixture. TEA was needed to shift the chemical equilibrium towards the fully oximated product. Then, by potentiometric titration, the unreacted TEA portion was titrated with HCl of known concentration to pH 3.3 (Faix, O., Andersons, B., & Zakis, G. (1998). Determination of carbonyl groups of six round robin lignins by modified oximation and FTIR spectroscopy https: / / doi.org / 10.1515 / hfsg.1998.52.3.268). The oximation solution was a water - alcohol solution with NH2OH*HCl 0.2N and TEA 0.08N. To prepare it, 1.2 g of TEA was dissolved in 96% alcohol in a 50 - ml volumetric flask (TEA stock solution). In a second 50 - ml volumetric flask, 0.7 g of NH2OH*HCl was dissolved in 5 ml of water. From the TEA stock solution, 25 ml of the solution was taken out and placed in the second flask, and then alcohol was added until the volume was reached.

[0322] 80 mg of lignin (original or formylated) was placed in a sealable capped tube (captube), dissolved in 2 mL of DMSO, and 5 mL of the oximation solution was added. The air in the tube was displaced with nitrogen, and then the tube was sealed. The sealed tube was heated at 80 °C for 2 hours and stirred at 300 rpm. Then the cooled solution was transferred to a beaker and a small amount of water (about 1 mL) was added. The excess TEA was potentiometrically titrated with 0.1N HCl to pH 3.3. The amount of carbonyl groups was calculated using the following equation.

[0323]

[0324] where a0, b0, c0 are the volumes (ml) of 0.1N HCl used for the blank titration, a is the volume (ml) of 0.1N HCl used for the sample titration, A is the weight (mg) of the lignin or formylated lignin analyzed, C is the weight (mg) of the lignin or formylated lignin in the blank c0, f is the titer of 0.1N HCl, and 280.1 is the mass (mg) of the CO group equivalent to 1 ml of 0.1N HCl multiplied by 100.

[0325] Due to the excessive use of TEA, carboxyl groups or other strongly acidic groups in lignin or formylated lignin may consume TEA during oximation. This is a significant source of increased CO. To avoid this type of error, a second pair of blank experiments (blanks b0 and c0) is required.

[0326] To check the reproducibility of the method, each titration was performed three times. The final volume of 0.1N HCl for each titration was derived from the mathematical average of the volumes found in each test of the same titration. The results of the oximation reaction are reported in Table 1 below.

[0327] Table 1

[0328] Sample %CO Mmol CO / g lignin Original lignin 0.21 0.08 Formylated lignin 1.92 0.62

[0329] As shown in Table 1, the original lignin exhibited a lower CO content than the formylated lignin. Specifically, they were found to be 0.21% and 1.92% respectively. This result indicates that the Reimer-Tiemann reaction is applicable to the formylation of lignin, leading to the generation of aldehyde groups.

[0330] Synthesis of lignin-pyrrole adducts

[0331] Example 10

[0332] Preparation of lignin / SP adducts. Reaction of formylated lignin with SP

[0333] 10 g of formylated lignin was dispersed in 50 mL of toluene, while 1 g of SP was dissolved in 50 mL of THF. The two solutions were mixed and stirred in a 250 mL flask at a temperature of 140 °C for 10 hours in the presence of 1% w / w acid catalyst (H2SO4). A Dean-Stark apparatus was used to remove the water formed during the reaction and to shift the equilibrium towards the formation of the product. The latter was finally recovered by filtration and washed with deionized water to remove unreacted SP.

[0334] Tollen's test, FT-IR (ATR) analysis and elemental analysis were performed on the formylated lignin / SP adduct.

[0335] Tollen's test was carried out as a qualitative test to check for the presence of aldehyde functional groups. Small aliquots of the original lignin, formylated lignin and formylated lignin / SP adduct were placed in three different glass test tubes and Tollen's reagent was added. The tubes were sonicated for 15 minutes to facilitate the dissolution of the lignin. The tubes were then heated in an oil bath at 50 °C for 1 hour and finally stored at room temperature for 24 hours.

[0336] Unlike vials containing native lignin and formylated lignin / SP adducts, vials containing formylated lignin produce a silver mirror. The absence of a silver mirror in vials with formylated lignin / SP adducts can be assumed to be due to the substantially absent aldehyde groups as a result of their reaction with SP.

[0337] FT-IR (ATR) spectra of formylated lignin (curve B) and formylated lignin / SP adduct (curve A) are shown in Figure 2 . The spectrum of formylated lignin shows characteristic peaks of aldehyde groups, especially C=O stretching at 1695 cm -1 and C-H stretching at 2640 cm -1 . In the spectrum of formylated lignin / SP, these peaks are absent, and a new peak appears at about 765 cm -1 . This peak can be attributed to the out-of-plane hydrogen (OPLA) of SP, as reported in (Barbera, V. et al., (2018). Domino reaction for the sustainable functionalization of few-layer graphene. Nanomaterials, 9(1), 44). This experimental evidence indicates that the pyrrole ring is retained in the formylated lignin / SP adduct. The absence of aldehyde functional groups in the formylated lignin / SP adduct indicates that the hydroxyl groups of SP react with formylated lignin to produce acetals and / or hemiacetals.

[0338] Elemental analysis by monitoring the nitrogen content was performed to quantitatively evaluate SP in the formylated lignin / SP adduct compared to native lignin and formylated lignin. The results are reported in Table 2.

[0339] Table 2

[0340] Sample N content % <![CDATA[SP content phl a > Original lignin 0.04 - Formylated lignin 0.06 - Formylated lignin / SP adduct 0.52 9

[0341] a : parts per hundred parts of lignin

[0342] As shown in Table 2, native lignin and formylated lignin exhibit lower nitrogen content relative to the formylated lignin / SP adduct. The increase in nitrogen is due to the presence of SP containing a pyrrole ring in its structure.

[0343] Example 11

[0344] Preparation of lignin / APTESP adduct

[0345] In a 250 μL round-bottom flask equipped with a magnetic stirrer, 10 g of lignin and acetone were successively poured in. A solution of 1 g of APTESP in 4 mL of acetone was prepared. This solution was dropped into the dispersion of lignin in acetone. Ultrasonic treatment was carried out for 5 minutes. Then, the solvent (acetone) was removed by using a rotary evaporator to dry the system, and then the system was treated at 120 °C for 4 hours under magnetic stirring (300 rpm). The final adduct was washed with acetone to remove unreacted pyrrole compounds.

[0346] FT-IR (ATR) analysis and elemental analysis were performed on the lignin / APTESP adduct.

[0347] The FT-IR (ATR) spectra of lignin (curve B) and the lignin / APTESP adduct (curve A) are shown in Figure 3 . In the spectrum of the lignin / APTESP adduct (curve A), typical signals of pyrrole molecules could be identified. Near 765 cm -1 , the out-of-plane (OPLA) mode of APTESP could be detected, while the shoulder peak at 1230 cm -1 was attributed to the stretching vibration of Si-O. The detection of the OPLA peak could indicate that after the functionalization reaction, the pyrrole ring retained its properties.

[0348] Based on these results and without being bound by any specific theory, it could be assumed that a reaction occurred between the silyl groups of APTESP and the hydroxyl groups of lignin.

[0349] Elemental analysis was carried out to quantitatively evaluate APTESP in the lignin / APTESP adduct by monitoring the nitrogen content compared with the original lignin. The results are reported in Table 3.

[0350] Table 3

[0351] Sample N content % <![CDATA[APTESP content phl a > Original lignin 0.04 - Lignin / APTESP adduct 0.17 3.2

[0352] a : parts per hundred parts of lignin

[0353] The lignin / APTESP adduct had a nitrogen content of 0.17%, which corresponded to 3.26% of APTESP, while lignin had a very low nitrogen content.

[0354] Example 12

[0355] Preparation of lignin / GlyP adduct

[0356] In a 250 ml flask, 10 g of lignin and 1 g of GlyP were dispersed in THF, and the solution was mixed and stirred for 10 h at a temperature of 120 °C in the presence of 1 % w / w of an acid catalyst (H2SO4). A Dean-Stark apparatus was used to remove the water formed during the reaction and to shift the equilibrium towards the formation of the product. The latter was finally recovered by removing the solvent using a rotary evaporator and washed with ethyl acetate to remove the unreacted GlyP.

[0357] The lignin / GlyP adduct was subjected to FT-IR (ATR) analysis and elemental analysis.

[0358] The FT-IR (ATR) spectra of lignin (curve B) and the lignin / GlyP adduct (curve A) are shown in Figure 4 . In the spectrum of the lignin / GlyP adduct, the typical signals of the pyrrole molecule could be identified. Near 765 cm -1 , the out-of-plane (OPLA) mode of GlyP could be detected. The detection of the OPLA peak could indicate that the pyrrole ring retained its properties after the functionalization reaction.

[0359] Based on these results and without being bound by any particular theory, it could be assumed that a reaction occurred between the carboxyl group of GlyP and the hydroxyl group of lignin.

[0360] Elemental analysis was carried out to quantitatively evaluate the GlyP in the lignin / GlyP adduct by monitoring the nitrogen content compared to the original lignin. The results are reported in Table 4.

[0361] Table 4

[0362] Sample N content % <![CDATA[GlyP content phl a > Original lignin 0.04 - Lignin / GlyP adduct 0.41 4.28

[0363] a : parts per hundred parts of lignin

[0364] The lignin / GlyP adduct had a nitrogen content of 0.41 %, which corresponded to 4.28 % of GlyP, while lignin had a very low nitrogen content.

[0365] Preparation and characterization of rubber compounds

[0366] Rubber compounds were prepared using carbon black (CB) as the sole filler and CB-(original lignin) or CB-(lignin / APTESP) or CB-(lignin / SP) as mixed filler systems. Two levels of sulfur were used: low (2 phr) and high (8.3 phr) sulfur content.

[0367] Examples R1-R6

[0368] Preparation of rubber compounds with low sulfur content

[0369] Table 5 below shows the composition of the vulcanizable elastomeric compounds R1 to R6. All amounts are expressed in phr. The lignin / APTESP adduct contains 3.3 phl of APTESP, and the lignin / SP adduct contains 9.5 phl of SP.

[0370] R1 is a reference composition. R2 and R3 are comparative compositions, and R4 to R6 are compositions of the present invention.

[0371] Table 5

[0372]

[0373]

[0374] NR: Coagulated natural rubber, obtained by centrifugation and from the coagulation of natural rubber latex HA stabilized with ammonia (60 wt% - sold by Von Bundit Co., Ltd);

[0375] CB: Carbon black, N326, Cabot Corporation;

[0376] Stearic acid: Stearic acid, Undesa;

[0377] ZnO: Zinc oxide, Zincol Ossidi;

[0378] 6PPD: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, Solatia Eastman;

[0379] TBBS: N-tert-butyl-2-benzothiazolesulfenamide, NZ / EGC, Lanxess;

[0380] Sulfur: Redball Superfine, International Sulfur Inc.

[0381] Lignin and the adducts of lignin with pyrrole compounds are fed as masterbatches into the rubber compound in natural rubber.

[0382] With the help of magnetic stirring, the raw lignin and the adducts of lignin with pyrrole compounds are dispersed in distilled water. Then the NR latex block is added to this suspension, and the mixture is stirred for 1 hour. The mixture is precipitated by adding acetic acid, the resulting masterbatch is extruded, cut into small pieces and washed several times with distilled water to remove any residual traces of acetic acid. Finally, the masterbatch is dried at room temperature. The total amount of the masterbatch and the relative amounts of NR and the raw lignin or lignin adducts are those used in the rubber compound.

[0383] By using one with 55 cm3 The composite material was prepared by melt blending in an internal Brabender mixer. First, the masterbatch from NR latex was fed into the mixer at a temperature of 80 °C and plasticized for 2 minutes. Then the temperature of the mixer was lowered to 50 °C and CB was added. After plasticizing for 4 minutes, ZnO, stearic acid and 6PPD were added and mixed for 2 minutes. Finally, TBBS and sulfur were added at the same temperature and plasticized for another 2 minutes. Then the final rubber compound was discharged.

[0384] Samples of rubber compounds R1 - R6 were subjected to MDR rheological analysis, dynamic - mechanical analysis (axial mode) and tensile testing. The results are summarized in Tables 6 to 8 below.

[0385] Table 6

[0386] R1 R2 R3 R4 R5 R6 MH [dNm] 15.4 14.9 14.1 19.7 15.1 19.7 ML [dNm] 2.0 1.9 1.4 2.0 2.0 1.5 MH - ML [dNm] 13.4 13.0 12.6 17.6 13.0 18.1 t90 [min] 4.0 3.6 3.8 3.3 3.3 3.6 tS1 [min] 2.4 2.3 2.4 2.1 2.1 2.0 Curing rate [dNm / min] 8.3 9.7 8.9 14.3 10.8 11.5

[0387] When 5 phr of raw lignin was used instead of 5 phr of carbon black (R2), a slight change in the parameters obtained from the rheological experiment was observed compared to R1. Increasing the amount of lignin to 10 phr (R3) resulted in a decrease in the modulus value compared to R1. Compounds R2 and R3 with raw lignin had faster vulcanization compared to R1, as revealed particularly by the value of the curing rate.

[0388] Compounds R4 and R5 containing APTESP as a lignin modifier led to an increase in M H and M H -M L values, as well as a higher curing rate, compared to reference R1 and comparative compounds R2 and R3.

[0389] Similarly, compound R6 containing SP as a lignin modifier led to an increase in M H and M H -M L values and the curing rate.

[0390] The results of the rheometer tests showed that functionalizing lignin with pyrrole compounds led to the formation of adducts that are chemically reactive towards elastomer chains.

[0391] Table 7

[0392]

[0393]

[0394] △E': E'(10 °C) - E'(70 °C)

[0395] Replacing carbon black with raw lignin (R2 and R3) led to similar E' values compared to reference R1.

[0396] Compared to reference R1, for two lignin contents: 5 phr and 10 phr, using lignin / APTESP instead of carbon black (R4 and R5) results in higher E' values and lower tanδ values at each temperature.

[0397] Compared to reference R1, using lignin / SP instead of carbon black (R6) results in higher E' values and lower / similar tanδ values at each temperature.

[0398] The results of axial dynamic mechanical testing indicate that functionalizing lignin with a pyrrole compound results in the formation of an adduct that is chemically reactive with elastomer chains.

[0399] Table 8

[0400] R1 R2 R3 R4 R5 R6 Ca1 (MPa) 2.25±0.22 2.04±0.01 2.06±0.04 3.21±0.13 2.23±0.13 3.14±0.07 Ca2 (MPa) 6.24±0.60 5.72±0.11 4.87±0.14 9.12±0.40 6.33±0.34 8.41±0.19 Ca3 (MPa) 13.57±0.86 11.75±0.23 9.78±0.24 17.72±0.67 12.01±0.54 16.45±0.23 CR (MPa) 30.81±0.43 28.18±1.34 27.05±0.49 25.44±0.90 24.89±0.38 24.77±0.91 AR (%) 505.3±10.4 514.3±20.31 572.1±8.64 389.2±18.19 452.7±0.59 387.5±10.91 <![CDATA[Energy (MJ / cm 3 )]]> 59.18±1.47 60.22±4.38 61.58±1.28 42.01±2.92 43.11±1.60 37.42±2.23

[0401] Compared to reference R1, replacing CB with raw lignin (R2 and R3) results in lower stress values at each elongation and break, resulting in similar or greater elongation at break and similar fracture energy.

[0402] Replacing 5 phr of CB with 5 phr of lignin / APTESP or lignin / SP results in higher stress values up to 300% elongation, and thus results in lower final properties compared to reference R1.

[0403] The results of axial dynamic mechanical testing indicate that functionalizing lignin with a pyrrole compound results in the formation of an adduct that is chemically reactive with elastomer chains.

[0404] Examples R7 - R13

[0405] Preparation of rubber compounds with high sulfur content

[0406] The following Table 9 shows the composition of vulcanizable elastomer compounds R7 to R13. All amounts are in phr. The lignin / APTESP adduct contains 3.3 phl of APTESP and the lignin / SP adduct contains 9.5 phl of SP.

[0407] R7 is a reference composition. R8 and R9 are comparative compositions, and R10 to R13 are compositions of the present invention.

[0408] Table 9

[0409] R7 R8 R9 R10 R11 R12 R13 NR 100 100 100 100 100 100 100 CB 50 40 30 40 30 40 30 Original lignin - 10 20 - - - - Lignin / APTESP - - - 10.3 20.6 - - Lignin - - - 10 20 - - APTESP - - - 0.3 0.6 - - Lignin / SP - - - - - 11 22 Lignin - - - - - 10 20 SP - - - - - 1 2 Stearic acid 5 5 5 5 5 5 5 ZnO 6 6 6 6 6 6 6 6PPD 2 2 2 2 2 2 2 CBS 1 1 1 1 1 1 1 Sulfur 8.3 8.3 8.3 8.3 8.3 8.3 8.3

[0410] NR: Coagulated natural rubber, obtained by centrifugation and obtained from the coagulation of natural rubber latex HA stabilized with ammonia (60 wt% - sold by Von Bundit Co., Ltd);

[0411] CB: Carbon black, N326, Cabot Corporation;

[0412] Stearic acid: Stearol, Undesa;

[0413] ZnO: Zinc oxide, Zincol Ossidi;

[0414] 6PPD: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, Solatia Eastman;

[0415] CBS: N-cyclohexylbenzothiazole-2-sulfenamide, Rubenamid C, General Quimica;

[0416] Sulfur: Redball Superfine, International Sulfur Inc.

[0417] Lignin and the adduct of lignin and pyrrole compound are fed as masterbatch into the rubber compound in natural rubber.

[0418] With the help of magnetic stirring, the raw lignin and the adduct of lignin and pyrrole compound are dispersed in distilled water. Then the NR latex block is added to this suspension and the mixture is stirred for 1 hour. The mixture is precipitated by adding acetic acid, the obtained masterbatch is extruded, cut into small pieces and washed several times with distilled water to remove any residual trace of acetic acid. Finally, the masterbatch is dried at room temperature. The total amount of the masterbatch and the relative amounts of NR and raw lignin or lignin adduct are those used in the rubber compound.

[0419] By using an internal Brabender mixer with a 55 cm 3 chamber, the composite material is prepared via melt blending. First, the masterbatch from the NR latex is fed into the internal mixer at a temperature of 80 °C and plasticized for 2 minutes. Then the temperature of the chamber is reduced to 50 °C and CB is added. After plasticizing for 4 minutes, ZnO, stearic acid and 6PPD are added and mixed for 2 minutes. Finally, CBS and sulfur are added at the same temperature and plasticized for another 2 minutes. Then the final rubber compound is discharged.

[0420] Samples of rubber compounds R7-R13 are subjected to MDR rheological analysis, dynamic-mechanical analysis (axial mode) and tensile testing. The results are summarized in Tables 10 to 12 below.

[0421] Table 10

[0422] R7 R8 R9 R10 R11 R12 R13 MH [dNm] 21.3 19.7 14.0 29.9 21.0 26.1 18.2 ML [dNm] 1.9 1.7 1.8 2.4 1.6 1.9 1.6 MH - ML [dNm] 19.4 18 12.2 27.5 19.4 24.2 16.6 t90 [min] 4.9 4.3 4.3 4.5 4.4 4.9 4.2 tS1 [min] 2.3 2.1 1.8 2.0 2.3 2.3 2.2 Curing rate [dNm / min] 7.5 8.2 4.6 11.0 9.2 9.6 8.2

[0423] Compared with the reference compound R7, the substitution of CB with raw lignin (R8 and R9) resulted in similar ML values, thus resulting in similar viscosities, and resulting in lower M H 、M H -M L 、t s1 、t 90 and cure rate values. The decrease was particularly evident when 20 phr of lignin (R9) was used to replace 20 phr of CB. In particular, lignin had a greater impact on the cure rate and M H . Therefore, raw lignin does not promote the effective vulcanization and high density of the crosslinked network.

[0424] Compared with the reference compound R7, by replacing 10 phr of CB with 10 phr of lignin adduct (with both APTESP and SP), M H 、M H -M L and cure rate values increased significantly, while t s1 and t 90 values remained basically the same.

[0425] Compared with the reference compound R7, by replacing 20 phr of CB with 20 phr of lignin adduct with APTESP, M H 、M H -M L 、t s1 and t 90 values remained basically the same, while the cure rate increased.

[0426] Compared with the reference compound R7, by replacing 20 phr of CB with 20 phr of lignin adduct with SP, M H 、M H -M L and t 90 values decreased, while t s1 value remained basically the same and the cure rate value increased.

[0427] Considering that the lignin / SP adduct contains a larger amount of pyrrole compounds relative to the lignin / APTESP adduct, it can be assumed that the different results may be due to the interaction of pyrrole compounds with sulfur and sulfur-based crosslinking chemicals. Pyrrole compounds can act as "sulfur scavengers" and have a negative impact on crosslinking.

[0428] Table 11

[0429]

[0430]

[0431] △E': E'(10 °C) - E'(70 °C)

[0432] Compared to the reference compound R7, replacing CB with native lignin (R8 and R9) resulted in lower E' values and higher Tanδ values at all temperatures. This clearly indicates that native lignin is not a reinforcing filler.

[0433] Compared to the reference compound R7, replacing CB with lignin adducts (both with APTESP (R10 and R11) and SP (R12 and R13)) resulted in higher E' values and lower Tanδ values at all temperatures.

[0434] These results indicate that the lignin adducts act as reinforcing fillers and have better results compared to CB.

[0435] Table 12

[0436] R7 R8 R9 R10 R11 R12 R13 Ca1 (MPa) 3.8 3.7 2.9 4.7 4.1 4.5 3.8 Ca2 (MPa) 8.1 7.5 5.6 12.2 9.3 11.1 8.7 CR (MPa) 9.7 10.4 9.9 11.8 10.9 12.4 10.8 AR (%) 242.3 289.9 328.2 221.8 206.6 220.5 235.6 <![CDATA[Energy (MJ / cm 3 )]]> 11.1 15.1 15.4 12.2 11.4 12.3 11.6

[0437] Compared to the reference compound R7, replacing CB with native lignin (R8 and R9) led to lower stress values at 100% and 200% elongation, especially when replacing a larger amount of CB, and led to similar fracture stress values and a greater elongation at break, with a correspondingly higher fracture energy. These data indicate that native lignin does not act as an effective reinforcing filler.

[0438] Compared to the reference compound R7, replacing CB with lignin adducts having both APTESP (R10 and R11) and SP (R12 and R13) resulted in higher stress values at 100% and 200% elongation and at break, with similar (slightly lower) elongation at break values, and higher (for 10 phr CB replacement) or similar (for 20 phr CB replacement) fracture energy values. These findings indicate that the lignin adducts act as reinforcing fillers.

[0439] Examples R14 - R18

[0440] Preparation of rubber compounds with high sulfur content

[0441] The following Table 13 shows the composition of the vulcanizable elastomer compounds R14 to R18. All amounts are in phr. The lignin / APTESP adduct contains 3.3 phl of APTESP, the lignin / SP adduct contains 9.5 phl of SP, and the lignin / GlyP adduct contains 4.2 phl of GlyP.

[0442] R14 is the reference composition. R15 is the comparative composition, and R16 to R18 are the compositions of the present invention.

[0443] Table 13

[0444] R14 R15 R16 R17 R18 NR 100 100 100 100 100 CB 50 35 35 35 35 Original lignin - 15 - - - Lignin / APTESP - - 15.4 - - Lignin - - 15 - - APTESP - - 0.4 - - Lignin / SP - - - 16.5 - Lignin - - - 15 - SP - - - 1.5 - Lignin / GlyP - - - - 15.6 Lignin - - - - 15 GlyP - - - - 0.6 Stearic acid 5 5 5 5 5 ZnO 6 6 6 6 6 6PPD 2 2 2 2 2 CBS 1 1 1 1 1 Sulfur 8.3 8.3 8.3 8.3 8.3

[0445] NR: Coagulated natural rubber obtained by coagulating natural rubber latex HA, obtained by centrifugation and stabilized with ammonia (60% by weight - sold by Von Bundit Co., Ltd);

[0446] CB: Carbon black, N326, Cabot Corporation;

[0447] Stearic acid: Stearic acid, Undesa;

[0448] ZnO: Zinc oxide, Zincol Ossidi;

[0449] 6PPD: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, Solatia Eastman;

[0450] CBS: N-cyclohexylbenzothiazole-2-sulfenamide, Rubenamid C, General Quimica;

[0451] Sulfur: Redball Superfine, International Sulfur Inc.

[0452] Lignin and the adduct of lignin and a pyrrole compound are fed as masterbatches into the rubber compound as natural rubber.

[0453] With the help of magnetic stirring, the raw lignin and the adduct of lignin and a pyrrole compound are dispersed in distilled water. Then the NR latex block is added to this suspension and the mixture is stirred for 1 hour. The mixture is precipitated by adding acetic acid, the resulting masterbatch is extruded, cut into small pieces and washed several times with distilled water to remove any residual traces of acetic acid. Finally, the masterbatch is dried at room temperature. The total amount of the masterbatch and the relative amounts of NR and raw lignin or lignin adduct are those used in the rubber compound.

[0454] By using an internal Brabender mixer with a 55 cm 3 chamber, the composite material is prepared via melt blending. First, the masterbatch from the NR latex is fed into the internal mixer at a temperature of 80 °C and plastisized for 2 minutes. Then the temperature of the chamber is lowered to 50 °C and CB is added. After plastisizing for 4 minutes, ZnO, stearic acid and 6PPD are added and mixed for 2 minutes. Finally, CBS and sulfur are added at the same temperature and plastisized for another 2 minutes. Then the final rubber compound is discharged.

[0455] Samples of rubber compounds R14 to R18 were subjected to MDR rheological analysis, dynamic-mechanical analysis (axial mode), and tensile testing. The results are summarized in Tables 14 to 16 below.

[0456] Table 14

[0457]

[0458]

[0459] Compared to reference compound R14, replacing CB with native lignin (R15) resulted in similar M L values, thus resulting in similar viscosities, and in lower M H and M H - M L and t s1 and cure rate values. In particular, lignin had a greater effect on the cure rate and M H . Thus, native lignin does not promote the effective vulcanization and high density of the crosslinked network.

[0460] Compared to reference compound R14, by replacing 15 phr of CB with any lignin adduct (R16 - R18) at 15 phr, M H , M H - M L and cure rate values increased significantly, while t s1 and t 90 values remained essentially the same.

[0461] Table 15

[0462]

[0463] △E': E'(10 °C) - E'(70 °C)

[0464] Compared to reference compound R14, replacing CB with native lignin (R15) resulted in lower E' values at all temperatures and similar Tanδ values. This indicates that native lignin is not an effective reinforcing filler.

[0465] Compared to reference compound R14, by replacing 15 phr of CB with any lignin adduct (R16 - R18), higher E' values and lower Tanδ values were obtained at all temperatures. These results indicate that the adducts act as reinforcing fillers, with better results compared to CB.

[0466] Table 16

[0467] R14 R15 R16 R17 R18 Ca1 (MPa) 3.6 2.8 4.8 4.5 3.9 Ca2 (MPa) 7.9 5.5 11.8 10.4 9.4 Ca3 (MPa) - 8.9 - - - CR (MPa) 9.4 9.7 12.1 11.3 10.7 AR (%) 254.6 331.4 224.6 205.3 207.4 <![CDATA[Energy (MJ / cm 3 )]]> 11.1 15.1 12.4 10.9 11.4

[0468] Compared with the reference compound R14, replacing CB with the raw lignin (R15) resulted in lower stress values at 100% and 200% elongation, and led to similar fracture stress values and larger elongation at break, with correspondingly higher fracture energy. These data indicate that the raw lignin does not act as a reinforcing filler.

[0469] Compared with the reference compound R14, by replacing CB with lignin adducts (R16 - R18), higher stress values at 100% and 200% elongation and at break were obtained, with similar elongation at break values and higher or similar fracture energy values. These findings suggest that the lignin adducts act as reinforcing fillers.

[0470] Examples R19 - R23

[0471] Preparation of low - sulfur - content rubber compounds with lignin / lignin adducts as the sole reinforcing filler

[0472] Table 17 below shows the compositions of the vulcanizable elastomer compounds R19 to R23. All amounts are expressed in phr. The lignin / APTESP adduct contains 3.3 phl of APTESP.

[0473] R19 - 21 are comparative compositions, and R22 and R23 are the compositions of the present invention.

[0474] Table 17

[0475]

[0476]

[0477] NR: Coagulated natural rubber, obtained by centrifugation and obtained from the coagulation of ammonia - stabilized natural rubber latex HA (60 wt% - sold by Von Bundit Co., Ltd);

[0478] Stearic acid: Stearite, Undesa;

[0479] ZnO: Zinc oxide, Zincol Ossidi;

[0480] 6PPD: N - (1,3 - dimethylbutyl) - N'-phenyl - p - phenylenediamine, Solatia Eastman;

[0481] TBBS: N - tert - butyl - 2 - benzothiazole sulfenamide, NZ / EGC, Lanxess;

[0482] Sulfur: Redball Superfine, International Sulfur Inc.

[0483] Lignin and the adduct of lignin and pyrrole compound are fed as masterbatch into the rubber compound for natural rubber.

[0484] With the aid of magnetic stirring, the raw lignin and the adduct of lignin and pyrrole compound are dispersed in distilled water. Then the NR latex block is added to this suspension and the mixture is stirred for 1 hour. The mixture is precipitated by adding acetic acid, the obtained masterbatch is extruded, cut into small pieces and washed several times with distilled water to remove any residual trace of acetic acid. Finally, the masterbatch is dried at room temperature. The total amount of the masterbatch and the relative amounts of NR and raw lignin or lignin adduct are those used in the rubber compound.

[0485] By using an internal Brabender mixer with a chamber of 55 cm 3 the composite material is prepared via melt blending. First, the masterbatch from the NR latex is fed into the internal mixer at a temperature of 80 °C and plastisized for 2 minutes. Then the temperature of the chamber is reduced to 50 °C and lignin or lignin adduct is added according to the formulation. After plastisizing for 4 minutes, ZnO, stearic acid and 6PPD are added and mixed for 2 minutes. Finally, TBBS and sulfur are added at the same temperature and plastisized for another 2 minutes. Then the final rubber compound is discharged.

[0486] Specimens of rubber compounds R19 to R23 are subjected to MDR rheological analysis, dynamic-mechanical analysis (axial mode) and tensile testing. The results are summarized in Tables 18 to 20 below.

[0487] Table 18

[0488] R19 R20 R21 R22 R23 MH [dNm] 6.2 4.7 3.9 6.2 7.7 ML [dNm] 1.1 0.9 0.9 1.6 1.8 MH - ML [dNm] 5.1 3.8 3 4.6 5.9 t90 [min] 3.9 3.1 3.2 2.8 4.7 tS1 [min] 2.5 1.9 1.9 2.3 3.1 Curing rate [dNm / min] 3.6 3.2 2.5 9.2 3.7

[0489] Compared with the rubber compounds R20 and R21 filled with raw lignin, the use of lignin / APTESP in compounds R22 and R23 gives the rubber compounds higher M H values and an increased curing rate. This aspect can be attributed to the fact that raw lignin without any functionalization cannot interact with the sulfur vulcanizing components and / or rubber chains. Therefore, it can be explained why for the rubber composites filled with raw lignin, the M H values decrease by increasing the amount of lignin.

[0490] Table 19

[0491]

[0492] △E': E'(10 °C) - E'(70 °C)

[0493] The results showed two different trends for the rubber compounds filled with 10 phr or 20 phr of filler. The compound filled with 20 phr of lignin / APTESP adduct (R23) showed higher E' values at all temperatures compared to the compound filled with 10 phr of raw lignin (R21), while no significant difference was observed between the rubber compounds filled with 10 phr of lignin / APTESP (R22) or raw lignin (R20). Notably, the NR compound filled with 20 phr of lignin / APTESP adduct (R23) showed a significant increase in the E' value with increasing temperature. The increase in the elastic modulus with temperature is a typical feature of entropy elasticity.

[0494] Table 20

[0495] R19 R20 R21 R22 R23 Ca0.5 (MPa) 0.59 0.65 0.66 0.63 0.69 Ca1 (MPa) 0.87 1.02 1.01 0.96 0.97 Ca3 (MPa) 2.07 2.67 2.62 3.13 2.02 CR (MPa) 13.33 15.62 13.73 18.45 14.91 AR (%) 584.28 600.01 600.32 587.39 623.08 <![CDATA[Energy (MJ / cm 3 )]]> 18.74 25.91 23.09 14.44 21.92

[0496] For all compounds, the stress-strain curves at 50% and 100% elongation were similar, probably reflecting the low filler concentration. Some differences were observed in the fracture properties of the compounds filled with lignin / APTESP (R22 and R23), which had improved fracture loads relative to the reference compound (R19) and the corresponding comparative compositions (R20 and R21). The compound filled with 10 phr of lignin / APTESP (R22) showed the highest reinforcement at 300% elongation relative to all other rubber compounds.

Claims

1. An adduct of lignin and a pyrrole derivative, wherein the lignin contains at least one functional group selected from hydroxyl (-OH), carboxyl (-COOH), ester (-COOR), and aldehyde (-CHO), and wherein the pyrrole derivative has the following general formula (I): wherein R1 - R4 are independently selected from a hydrogen atom, a C1 - C3 alkyl group, a straight-chain or branched C2 - C 10 alkenyl or alkynyl group, an aryl group, a straight-chain or branched C7 - C 16 alkyl-aryl group, a straight-chain or branched C7 - C 16 alkenyl-aryl group, a straight-chain or branched C7 - C 16 alkynyl-aryl group, a heteroaryl group, -CO-NHW' and -CO-OW” "W" is selected from a hydrogen atom, a straight-chain or branched C1-C 10 alkyl group, a straight-chain or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a straight-chain or branched C7-C 16 alkyl-aryl group, a straight-chain or branched C7-C 16 alkenyl-aryl group, a straight-chain or branched C7-C 16 alkynyl-aryl group, and a heteroaryl group, W and W' are independently selected from a hydrogen atom, a linear or branched C1-C 10 alkyl group, a linear or branched C2-C 10 alkenyl or alkynyl group, a linear or branched C7-C 16 alkyl-aryl group, a linear or branched C7-C 16 alkenyl-aryl group, a linear or branched C7-C 16 alkynyl-aryl group, heteroaryl group, aryl group, cyclohexyl group, and a residue having the following formula (II): wherein M, Q, and J are independently selected from a hydrogen atom, an amino group, a hydroxyl group, a linear or branched C1-C 10 alkyl group, a linear or branched C2-C 10 alkenyl or alkynyl group, and a residue having the following formula (III): wherein I is an integer from 0 to 12, and R5 and R6 are independently selected from a hydrogen atom, a linear or branched C1-C 10 alkyl group, a linear or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a linear or branched C7-C 16 alkyl-aryl group, a linear or branched C7-C 16 alkenyl-aryl group, a linear or branched C7-C 16 alkynyl-aryl group, a heteroaryl group, a carboxyl group, and -(CH2) o -S-R 16 , where o is an integer from 0 to 2, and R 16 is selected from a hydrogen atom or a C1-C3 alkyl group, and Gr is selected from the group consisting of the following residues (IV) to (IX): where m is an integer from 1 to 2, n is an integer from 1 to 4, p is an integer from 2 to 4, q is an integer from 1 to 30, and R7-R 15 are independently selected from a hydrogen atom, a straight-chain or branched C1-C 10 alkyl group, a straight-chain or branched C2-C 10 alkenyl or alkynyl group, an aryl group, a straight-chain or branched C7-C 16 alkyl-aryl group, a straight-chain or branched C7-C 16 alkenyl-aryl group, a straight-chain or branched C7-C 16 alkynyl-aryl group, and a heteroaryl group, and R 11 -R 13 may also be a straight-chain or branched C1-C 10 alkoxy group.

2. A tire for a vehicle wheel, comprising at least one structural component, the structural component comprising a vulcanized elastomeric stock obtained by vulcanizing a vulcanizable elastomeric composition, the vulcanizable elastomeric composition comprising: (i) 100 phr of a composition comprising at least one diene elastomeric polymer selected from natural and synthetic diene elastomeric polymers, (ii) 0 to 100 phr of a carbon black reinforcing filler, (iii) 2 to 100 phr of the adduct of lignin and a pyrrole derivative according to claim 1, and (iv) 0.1 to 12 phr of at least one vulcanizing agent.

3. A green tire structural component, comprising a vulcanizable elastomeric composition, the vulcanizable elastomeric composition comprising: (i) 100 phr of a composition comprising at least one diene elastomeric polymer selected from natural and synthetic diene elastomeric polymers, (ii) 0 to 100 phr of a carbon black reinforcing filler, (iii) 2 to 100 phr of the adduct of lignin and a pyrrole derivative according to claim 1, and (iv) 0.1 to 12 phr of at least one vulcanizing agent.

4. A vulcanizable elastomeric composition, comprising: (i) 100 phr of a composition comprising at least one diene elastomeric polymer selected from natural and synthetic diene elastomeric polymers, (ii) 0 to 100 phr of a carbon black reinforcing filler, (iii) 2 to 100 phr of the adduct of lignin and a pyrrole derivative according to claim 1, and (iv) 0.1 to 12 phr of at least one vulcanizing agent.

5. The tire for a vehicle wheel according to claim 2, or the structural component according to claim 3, or the elastomeric composition according to claim 4, characterized in that The vulcanizable elastomeric composition comprises the adduct of lignin and a pyrrole derivative according to claim 1 in an amount equal to or higher than 5 phr, preferably higher than 10 phr.

6. The tire for a vehicle wheel according to claim 2, or the structural component according to claim 3, or the elastomeric composition according to claim 4, characterized in that The vulcanizable elastomeric composition comprises the adduct of lignin and a pyrrole derivative according to claim 1 in an amount lower than 75 phr, preferably lower than 50 phr.

7. The tire for a vehicle wheel according to claim 2, or the structural component according to claim 3, or the elastomeric composition according to claim 4, characterized in that The vulcanizable elastomeric composition comprises a carbon black reinforcing filler in an amount greater than 15 phr, preferably greater than 20 phr.

8. The tire for a vehicle wheel according to claim 2, or the structural component according to claim 3, or the elastomeric composition according to claim 4, characterized in that The vulcanizable elastomeric composition comprises a carbon black reinforcing filler in an amount lower than about 80 phr, preferably lower than about 60 phr.

9. The tire for a vehicle wheel according to claim 2, or the structural component according to claim 3, or the elastomeric composition according to claim 4, characterized in that, The vulcanizable elastomeric composition comprises from 1 phr to 70 phr, preferably from about 10 phr to about 60 phr, of at least one additional reinforcing filler selected from silica, silicate, alumina, aluminosilicate, such as sepiolite, palygorskite also known as attapulgite, montmorillonite, halloysite, etc., which may be modified and / or derivatized by acid treatment, calcium carbonate, kaolin, or a mixture thereof.

10. The tire for a vehicle wheel according to claim 2 or the structural component according to claim 3, wherein the structural component is selected from a carcass structure, a belt structure, an additional belt layer, a rubberized layer, a sidewall, a sidewall insert, a wear-resistant layer, a bead filler, a bead reinforcement layer, and a tread.

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