WO2016099512A1 - Microstructured composites for improved tire characteristics - Google Patents

Abstract

Methods of forming rubber-based composites and tire components that can incorporate the rubber-based composites are described. The methods can be utilized to form composites in which one or more formation materials incorporated in the composite can have a structure on the microscopic level. The materials that form the composite can be provided in the microstructured composite in a layered arrangement with one another, and can include at least about 20 layers, and the composite can include a large average number of layers, generally more than 20, per millimeter of composite thickness.

Description

MICROSTRUCTURED COMPOSITES FOR IMPROVED TIRE CHARACTERISTICS

FIELD

[0001] The present disclosure relates to methods for forming rubber based composites with controlled microstructuring of materials of the composites and to tire components incorporating the composites.

BACKGROUND

[0002] Polymeric composites are utilized in formation of tire components (e.g., treads, sidewalls, inner liners, etc.) to maximize multiple different desirable characteristics and provide a tire with the highest possible overall performance. For instance, crosslinked diene elastomers (rubbers) that form the basic matrix of many tire components have a low elastic modulus and are able to undergo extensive and reversible deformation under a broad range of conditions. Thus, the diene elastomers can provide excellent grip and flex characteristics to a tire component, even in extreme conditions of use (e.g., extremely high or low temperatures). In fact, in many instances it would be desirable to even further decrease the elastic modulus of tire components to offer further improvement in these areas. For example, a lower overall elastic modulus could provide increased wet traction capabilities to the tire tread.

[0003] Unfortunately, other desirable characteristics are not provided at optimal levels by diene elastomers. To obtain these characteristics in the tire component, additives are combined with the elastomeric polymers to provide a composite that has increased strength, wear performance, abrasion resistance, etc. The ongoing aim in tire manufacturing is to find the best combination of formation materials so as to maximize the overall qualities of the composite. Problematically, desirable characteristics often conflict, e.g., obtaining high wet and dry traction and rolling resistance and obtaining long wear and abrasion/cut resistance, and a trade-off must be accepted in the characteristics of the final composite. For example, while it would be desirable to reduce the elastic modulus of the tread to promote grip and the deformation of the tread with the ground it would likewise be desirable to increase the rigidity of the tread to promote wear performance. Problems concerning such contradictory desires have been approached by modifying the specific materials of the composites and the molecular interactions between the materials. For instance, additives of various sizes, hardness levels, and reactive functionality as well as variations in the particular elastomeric polymers used have been mixed and matched to provide the best possible compromise in desirable characteristics.

[0004] The methods used to combine the various materials of the compositions have also been subject to a certain amount of modification. For instance, the sequences of addition and the inclusion of bond formation between materials have been examined and modified to improve composite characteristics. Through all of the variations examined, however, the macroscopic combinatorial methods used (e.g., milling, mixing, etc.) have largely aspired to maximize distribution of the additive materials throughout the rubber matrix so as to form a homogenous composite.

[0005] What are needed in the art are combinatorial methods that can better promote the individual characteristics of the materials of rubber based composites and thus provide improved overall performance in tire components formed of the composites.

SUMMARY

[0006] Aspects and advantages of embodiments of the present disclosure will be set forth in part in the following description, or may be learned from the description, or may be learned through practice of the embodiments.

[0007] One example aspect of the present disclosure is directed to a tire component comprising a multilayered composite. For example, the multilayered composite can include about 20 or more layers adhered to one another and can have an average number of layers per millimeter of the thickness of about 20 or more. At least one of the layers can include a first formation material that includes a rubber and at least one other layer can include a second formation material. Other layers when present can independently include at least one of the first formation material and/or the second formation material and/or one or more other formation materials. The formation materials of the composite can differ from one another according to a mechanical property, chemical property, optical property, electronic property, or combination thereof. [0008] Tire components that can include the multilayered composite can include, without limitation, a tread, an undertread, a sidewall, a wire skim, an inner liner, a bead, an apex, or a carcass reinforcement

[0009] These and other features, aspects and advantages of various embodiments will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the related principles.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Detailed discussion of embodiments directed to one of ordinary skill in the art are set forth in the specification, which makes reference to the appended figures, in which:

[0011] FIG. 1 schematically illustrates two layers of a multilayer assembly in an exploded view.

[0012] FIG. 2 schematically illustrates two layers of a multilayer assembly in an exploded view, one of the layers including multiple formation materials arranged to form the layer.

[0013] FIG. 3 illustrates a micro-layered composite according to the present disclosure.

[0014] FIG. 4 illustrates another micro-layered composite according to the present disclosure.

[0015] FIG. 5 illustrates another micro-layered composite according to the present disclosure.

[0016] FIG. 6 illustrates another micro-layered composite according to the present disclosure.

[0017] FIG. 7 illustrates another micro-layered composite according to the present disclosure.

[0018] FIG. 8 graphically compares the friction coefficient of traditional rubber compositions with micro-layered composites of the present disclosure. DETAILED DESCRIPTION

[0019] Reference now will be made in detail to embodiments, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the embodiments, not limitation of the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments without departing from the scope or spirit of the present disclosure. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that aspects of the present disclosure cover such modifications and variations.

[0020] In general, the present disclosure is directed to methods of forming rubber-based composites and tire components that can incorporate the rubber-based composites. More specifically, the disclosed methods can be utilized to form composites in which one or more formation materials incorporated in the composite can have a dimension on the microscopic or nanoscopic level. Formation materials that form the composite can be provided in the composite in a layered arrangement, and the thickness of the individual layers can be on a micrometer scale, or even smaller in some embodiments. More specifically, the rubber based composite can include about 20 layers or more that can provide different formation materials of the composite in a structured arrangement. The composite can include a large number of layers, for example about 50 layers or more, about 100 layers or more, or about 1,000 layers or more in some embodiments. For example, and depending on the overall thickness of the rubber based composite, the rubber based composite can include thousands of layers in some embodiments, for instance from about 20 layers to about 1,500 layers, or from about 50 layers to about 1,000 layers.

[0021] The thickness of each of the layers in the formed composite can be quite small. As utilized herein, the term thickness generally refers to the distance between a first planar surface and a second parallel planar surface of a structure. For instance, and with reference to FIG. 1, the thickness of a layer 12 is the distance between the upper and lower surface of the layer (the upper surface being the visible surface in FIG. 1) that is normal to both the width w of the layer and the length 1 of the layer, both of which are measured across a surface of the layer 12. A plurality of layers can be assembled and compressed in a single or in multiple steps to form the composites such that the thickness of each layer adds to the others to form an overall thickness of the composite. For instance, following formation, the average number of layers per millimeter of thickness of the composite can be about 20 or more, about 50 or more, about 100 or more, about 250 or more, about 500 or more, or about 1 ,000 or more. In general, the average number of layers per millimeter of thickness of the composite can be about 2,000 or less, about 1 ,500 or less, or about 1 ,000 or less in some embodiments. For instance, the average number of layers per millimeter of thickness of the composite can be from about 20 to about 2,000, from about 50 to about 2,000, from about 50 to about 1 ,500, from about 50 to about 1 ,000, from about 100 to about 2,000, from about 100 to about 1 ,500, from about 100 to about 1 ,000, from about 250 to about 1 ,500, from about 250 to about 1 ,000, from about 500 to about 1 ,500, or from about 500 to about 1 ,000.

[0022] Individual layers of a composite and the formation material(s) that form each layer can be continuous across the width and/or length of the composite or can be discontinuous, which can add another dimension of variation to the composite and provide another level of design and control to the characteristics of the composite.

[0023] Through control of the structuring of the formation materials, the multilayered composites and the tire components formed of the composites can exhibit improved characteristics related to, and without limitation; impermeability, for instance in the inner liner; mechanical properties such as, modulus, wear, friction, traction, adhesion,

isotropic/anisotropic nature of characteristics, etc. of the composite as well as of a tire component formed with the composite, for example in the tire tread, the inner liner and so forth; electrical properties, for example in tire treads, tire sidewalls, etc.

[0024] By way of example, the friction coefficient of a multilayered composite formed according to the disclosed methods (and likewise a tire component incorporating the composite) can be about 120% or greater, about 130% or greater, or about 135% or greater in some embodiments of the friction coefficient of a traditionally formed composite of the same materials in which the materials are simply mixed and/or milled together. For example, a multilayered composite formed according to the disclosed methods can have a friction coefficient of about 0.35 or greater, about 0.36 or greater, or about 0.37 or greater in some embodiments.

[0025] Disclosed methods can improve adhesion between formation materials of a composite. For instance, materials that are generally incompatible with one another can be combined according to disclosed methods, and the materials can exhibit excellent adherence to one another in the formed composite. Of course, the methods can be utilized to combine compatible materials as well and the composite can exhibit improved overall characteristics. Moreover, while much of this discussion is directed to the formation of composites in which each layer includes a single formation material, and the formation materials of different layers differs in some respect, one of skill in the art will understand that the methods can be utilized to combine multiple different formation materials in multiple different layers. For instance, at least one layer can include a first formation material, and this layer can include only this first formation material or optionally can include this first formation in conjunction with one or more other formation materials. At least one other layer of the composite can include a second formation material that differs in some way from the first formation material, and this other layer can include only this second formation material or optionally can include this second formation material in conjunction with one or more other formation materials. These two types of layers can generally be included multiple times throughout the final composite.

[0026] A composite can include additional types layers formed of one or more other formation materials as well, and the composite not limited to two types of layers. For instance, when additional types of layers are present, these layers can include the first formation material and/or the second formation material and/or one or more additional formation materials in any combination. As utilized herein, the term "and/or" generally indicates that one or more of the cases it connects may occur. For example, the phrase "a layer including at least one of A and/or B and/or C" indicates that the layer can include one, two or all three of A, B, and C in any combination. That is, the layer can include A alone without B and without C, B alone without A and without C, C alone without A and without B, A and B without C, A and C without B, B and C without A, or all three of A, B, and C.

[0027] In forming a composite, two or more layers can be assembled together and the assembly thus formed can be compressed in one or multiple compression steps such that the assembly is compressed to a smaller thickness. In one embodiment, the compressing step can also adhere layers of the assembly to one another (in those embodiments in which the layers were not previously adhered to one another). For instance, as illustrated in an exploded view in FIG. 1, a multilayer assembly 10 can include a first layer 12 of a first formation material and a second layer 14 of a second formation material, optionally in conjunction with a plurality of additional layers of the same or different materials. Following combination of the layers, the assembly 10 can be compressed to decrease the thickness of the assembly and optionally to also adhere the layers 12, 14 to one another and form a multilayered composite. For example, compressing of assembled layers (which can be carried out in a single compressing step or multiple compressing steps) can decrease an original thickness of the assembled layers by about 5% or more, about 10% or more, about 25% or more, about 30%> or more, about 40%> or more, about 50%> or more, about 75% or more, about 90%> or more, about 95% or more or about 99% or more. For instance, the compressing can decrease the original thickness of the assembled layers by less than 100%, for example from about 20% to about 99%), from about 30%> to about 79%, from about 30%> to about 60%>, or from about 40%> to about 60% in some embodiments. By way of example, a plurality of assembled layers having an original total thickness (i.e., the thickness of all layers when assembled together) of 5 mm that, following compressing, has a thickness of 2.5 mm, would have the original thickness (5 mm) decreased by 50 % (5 mm x 50% = 2.5 mm; 5mm - 2.5 mm = 2.5 mm). Similarly, if following compressing the thickness of the assembled layers was 0.05 mm, the original thickness will have been decreased by 99% (5 mm x 99% = 4.95 mm; 5 mm - 4.95 mm = 0.05 mm).

[0028] The multilayer composite can be formed in a single assembly step or alternatively the assembly and compressing steps can be repeated one or more times to increase the number of layers of the product and to decrease the thickness of the assembly. For instance, two or more previously compressed multilayered composites can be assembled together and compressed to decrease the thickness of the assembly and optionally to also adhere the multilayered composites to one another. Individual multilayered composites that can be assembled together can be the same as one another or can differ. In one embodiment, a first multilayered composite can be assembled with additional layers that have not been previously compressed and/or adhered to one another, and this assembly can be compressed. Of course, an assembly step can include assembly of a previously compressed multilayer composite with layers that have not been previously compressed as well as with additional multilayer composites that have been previously compressed. This stacking and compressing process can be repeated to form a final composite that includes a plurality of layers adhered together.

[0029] At least two of the layers of a multilayer assembly can include formation materials that differ from one another in at least one aspect, and upon compression of the multilayered assembly, these different materials can maintain their individual identities such that the different materials can form discernable structures on the microscopic level. The terms "formation material" and "material" are used interchangeably herein and can refer to a single component substance or a multi-component substance. For instance, a rubber formation material can be a multi-component substance that can include, for example, one or more additives, fillers, curing agents, plasticizers and so forth in combination with one or more diene elastomers as is known. Similarly, a thermoplastic formation material can include one or more thermoplastic polymers in conjunction with one or more additives, fillers, additional polymers, nucleation agents, colorants, etc. A fiber/resin composite can also be considered a multi-component formation material, for instance a continuous fiber/resin reinforced pre-preg composite. A single component substance that can be utilized as a formation material can include, for example, a single component polymer (e.g., no additives in conjunction with the polymer), a metal layer, for instance in the form of metal fibers, metal strips, metal foils, etc., a carbon fiber layer, etc.

[0030] Two or more layers can be assembled according to any layer pattern. For instance, a plurality of layers of a first material and a plurality of layers of a second material can be assembled with every other layer of the assembly being formed of a different material, for instance in an A-B-A-B-A-B pattern in the case of two different types of layers or in an A-B-C-A-B-C pattern in the case of three different types of layers. Alternatively, a plurality of layers of a first material can be assembled adjacent to each other and one or more layers of a second material can be assembled adjacent to these first layers, for instance an A-B-B-B-A- A-B-B-B-A pattern. This assembly can then be compressed to form a multilayered composite having the desired materials distribution. Similarly, two or more multilayered composites can be assembled and compressed according to a predetermined design to provide the individual layer materials in a desired fashion. As such, the various formation materials of the final composite product can be provided in a regular distribution or an irregular distribution across the thickness of the composite, for instance an A-B-A-B-B-A-B-A-A-A pattern in the case of an irregular distribution of formation materials whereas the other exemplary patterns above would be examples of a regular distribution of formation materials. The pattern of the different material layers can be utilized to control the ultimate thickness of the different materials in the final product.

[0031] The composites can be formed with a plurality of different materials, and in one embodiment the materials used to form the layers can vary throughout the thickness of a composite. For instance, materials used to form external layers of a multilayer composite can differ from those used to form internal layers of a composite, for example as in a multilayered pattern of A-B-B-C-C-C-C-B-B-A. The pattern of the layered materials can change throughout the thickness of the composite as can the materials utilized throughout the composite. Any combination of types and patterns of materials and layers can be developed to control the desired characteristics of the multilayered composite.

[0032] Different formation materials can be combined in a single layer to form

microstructures of the different formation materials across the width and/or length of a single layer. For example, and as schematically illustrated in FIG. 2, a first layer 24 of a

multilayered assembly can be formed of a first material (e.g., a rubber based material) and a second layer 22 can be formed of a plurality of sections 21, 23, 25 at least two of which can be formed of different formation materials. The formation materials of some of the sections may be the same, e.g., the formation material of section 21 and section 25 may be the same and that of section 23 may be different, or all sections of a layer can be formed of different formation materials. Though illustrated as being arranged in a regular pattern of strips in FIG. 2, it will be understood that multiple formation materials of a single layer can be arranged in any geometric or otherwise organized pattern or can be arranged randomly throughout the layer. For instance, a series of squares, circles, etc., of a first formation material can be arranged with a second formation material surrounding the shapes in the plane of the layer surface. Crossing patterns of materials may be formed in different (e.g., adjacent) layers, and materials having a directional component (e.g., fibrous materials or long strips of materials) may be applied in a layer in a circumferential direction, an axial direction, or at some angle to the radial direction as determined by the final tire component to be formed including the multilayer composite. Any random or organized pattern and any number of formation materials can be utilized in forming a single layer.

[0033] Beneficially, through control of the starting layer thickness, the number and pattern of individual layers in the multilayered construct, the number and pattern of materials in individual layers, the number of compression steps, etc., the microstructures can be formed with a controlled geometry. For instance, microstructures can be formed as a continuous layer across the width of a composite or alternatively, microstructures can be formed so as to provide discontinuous microstructures across the width of the composite.

[0034] The preferred geometry of the formation materials in a composite can depend upon the final application of the composite. By way of example, when forming a composite for use as an impermeable inner liner, it may be preferred for one or more of the materials of the composite (e.g., a rubber material with high impermeability characteristics) to be provided as a continuous microstructure layer across the entire composite width and/or length. Alternatively, in those embodiments in which the composite can come under high force during use, it may be preferred to form the composite with discontinuous

microstructures within a continuous matrix material, so as to maximize force distribution throughout the matrix. Of course, combinations of continuous and discontinuous layers as well as combinations of single material layers and multi-material layers are also encompassed in the composite materials.

[0035] Materials utilized in forming layers of a composite can differ from one another according to at least one property. The property that differs between two formation materials can be, for example, mechanical properties, chemical properties, optical properties, electronic properties, and so forth as well as combinations of properties. Mechanical properties by which the materials can differ can include, without limitation, elastic modulus, tensile strength, elongation at break, Poisson's ratio, flexural modulus, flexural strength, hardness, flexural hysteresis, glass transition temperature, color, etc. Other differential properties can include, for instance, color, refractive index, conductivity, resistance, dielectric constant, crosslink density, isomerization, copolymer characteristics (e.g., block copolymer vs. random copolymer, etc.), and so forth.

[0036] By way of example, one of the layers of the composite can be formed of a more flexible material and can have a first elastic modulus and a second layer of the composite can be formed of a more rigid material and can have a second, higher elastic modulus, and these two layers can be combined with one another such that the composite includes distinct microstructures of one or both of the materials. For instance, the formation material of the more flexible layer can have an elastic modulus of about 20 megapascals (MPa) or less, about 10 MPa or less, or about 5 MPa or less in some embodiments. The formation material of the more flexible layer can have an elastic modulus of from about 0.5 MPa to about 5 MPa or from about 1 MPa to about 3 MPa in some embodiments. The formation material of the more rigid layer of the composite can have a higher elastic modulus, for instance about 10,000 MPa or greater, or about 20,000 MPa or greater in some embodiments. For instance, the formation material of the more rigid layer can have an elastic modulus of from about 25,000 MPa to about 100,000 MPa. [0037] The mechanical properties of materials of the composite can differ with regard to hardness. For instance, one of the layers of the composite can include a softer material and can have a first Shore A hardness, and a second layer of the composite include a harder material and can have a second, higher Shore A hardness. For instance, the softer material can have a Shore A hardness of about 50 or less, for instance about 40 or less, or from about 10 to about 35 in some embodiments, and the harder material can have a Shore A hardness of about 50 or greater, for instance about 60 or greater, or from about 70 to about 120 in some embodiments.

[0038] At least one of the layers of the composite can include rubber. The term rubber as utilized herein is considered to be synonymous with the term diene elastomer and is understood to mean, generally, an elastomer derived at least in part (i.e., a homopolymer or a copolymer) from diene monomers, that is to say from monomers bearing two (conjugated or unconjugated) carbon-carbon double bonds.

[0039] Diene elastomers may be classified, in a known manner, in two categories: those said to be "essentially unsaturated" and those said to be "essentially saturated". Generally, the expression "essentially unsaturated diene elastomer" is understood here to mean a diene elastomer resulting at least partly from conjugated diene monomers, having a number of diene units or units of diene origin (conjugated dienes) that is greater than 15% (mol %). Thus, for example, diene elastomers such as butyl rubbers or diene/a-olefin copolymers of the EPDM type do not fall within the above definition and may in particular be termed "essentially saturated diene elastomers" (small or very small number of units of diene origin, always less than 15%). Within the "essentially unsaturated" diene elastomer category, the expression "highly unsaturated diene elastomer" is understood in particular to mean a diene elastomer having a number of units of diene origin (conjugated dienes) that is greater than 50%.

[0040] Having given these definitions, it will be understood more particularly that a diene elastomer that can be used in the compositions according to the disclosure means:

(a) any homopolymer obtained by polymerizing a conjugated diene monomer having, for example, about 4 to about 12 carbon atoms;

(b) any copolymer obtained by copolymerizing one or more conjugated dienes with one another or with one or more vinylaromatic compounds having, for example, about 8 to about 20 carbon atoms; (c) a ternary copolymer obtained by copolymerizing ethylene, an α-olefm having, for example, about 3 to about 6 carbon atoms with an unconjugated diene monomer having, for example, about 6 to about 12 carbon atoms, such as for example the elastomers obtained from ethylene, propylene and an unconjugated diene monomer of the aforementioned type such as in one embodiment 1 ,4-hexadiene, ethylidene norbornene and dicyclo-pentadiene; and

(d) a copolymer of isobutene and isoprene (butyl rubber), and also the halogenated, in particular chlorinated or brominated, versions of this type of copolymer.

[0041] Although the present disclosure applies to any type of diene elastomer, a person skilled in the art of tires will understand that it can be beneficially utilized in one particular embodiment with essentially unsaturated diene elastomers, in particular of the (a) or (b) type above. Suitable conjugated dienes include, without limitation, 1,3-butadiene, 2-methyl-l,3- butadiene, 2,3-di(Ci-C₅ alkyl)-l,3-butadienes such as, for instance, 2, 3-dimethyl- 1,3- butadiene, 2,3-diethyl-l,3-butadiene, 2-methyl-3-ethyl- 1,3-butadiene, 2-methyl-3-isopropyl- 1,3 -butadiene, an aryl-l,3-butadiene, 1,3-pentadiene and 2,4-hexadiene.

[0042] The diene elastomer can be chosen from the group formed by polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), various butadiene copolymers, various isoprene copolymers, and blends of these elastomers. Such copolymers can be chosen from the group formed by butadiene-styrene (SBR) copolymers, whether the latter are prepared by polymerization in emulsion (ESBR) or in solution (SSBR), isoprene-butadiene (BIR) copolymers, isoprene-styrene (SIR) copolymers and isoprene-butadiene-styrene (SBIR) copolymers.

[0043] Among the polybutadienes, those that are suitable include those having a (mol %) content of 1,2 units between 4% and 80% or those having a (mol %) content of cis-1,4 units greater than 80%. Among the synthetic polyisoprenes, those that are suitable include cis-1,4- polyisoprenes, e.g., those having a (mol %) content of cis-1,4 bonds greater than 90%>.

[0044] Among the butadiene or isoprene copolymers, these are understood to mean the copolymers obtained by copolymerizing at least one of these two monomers with one or more vinylaromatic compounds having 8 to 20 carbon atoms. For example, copolymers may contain between 99% and 20%> by weight of diene units and between 1% and 80% by weight of vinyl-aromatic units. Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta- and para-methylstyrene, the commercial "vinyl-toluene" mixture, para-tert- butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesityrene, divinylbenzene and vinylnaphthalene. The copolymers may contain between 99% and 20% of diene units and between 1% and 80% of vinylaromatic units.

[0045] Embodiments of the present invention can use polyisoprenes and/or butadiene - styrene copolymers, including those having a styrene content of between 5% and 50%> by weight and more particularly, between 20%> and 40%>, a content of 1,2-bonds of the butadiene fraction of between 4% and 65%, and a content of trans-1,4 bonds of between 20%> and 80%>, butadiene -isoprene copolymers including those having an isoprene content of between 5% and 90% by weight and a glass transition temperature ("T_g"~measured in accordance with ASTM Standard D3418-03) of between -40 °C and -80 °C, isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight and a T_g of between -25 °C and -50 °C. In the case of butadiene-styrene-isoprene copolymers, those that are suitable include those having a styrene content of between 5% and 50% by weight and more particularly, between 10% and 40%, an isoprene content of between 15% and 60% by weight, and more particularly between 20% and 50%, a butadiene content of between 5% and 50%) by weight, and more particularly between 20% and 40%, a content of 1,2-units of the butadiene fraction of between 4% and 85%, a content of trans-1,4 units of the butadiene fraction of between 6% and 80%, a content of 1,2- plus 3,4-units of the isoprene fraction of between 5% and 70%, and a content of trans-1,4 units of the isoprene fraction of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a T_g of between -20 °C and -70 °C.

[0046] The elastomers and combinations of elastomers used can vary depending upon the particular tire component to be formed by the composite, as is known. For instance, in forming an inner liner, the predominant elastomer of the composition can be a butyl rubber, and in particular a butyl rubber chosen from the group of the essentially saturated diene elastomers consisting of copolymers of isobutene and of isoprene and their halogenated derivatives. In forming the inner liner, this essentially saturated elastomer to be used as a mixture with an elastomer chosen from the group of the highly unsaturated diene elastomers consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprene copolymers, butadiene/styrene copolymers, isoprene/butadiene copolymers, isoprene/styrene copolymers and isoprene/butadiene/styrene copolymers and the mixtures of these elastomers. [0047] The elastomers can have any structure which can depend on the polymerization conditions used, in particular on the presence or absence of a modifying and/or randomizing agent and on the amounts of modifying and/or randomizing agent employed. The elastomers can, for example, be block, random, sequential or microsequential elastomers and can be prepared in dispersion or in solution; they can be coupled and/or star-branched or also functionalized with a coupling and/or star-branching or functionalization agent. Mention may be made, for coupling to other components of a material such as carbon black, for example, of functional groups comprising a C— Sn bond or aminated functional groups, such as benzophenone, for example; mention may be made, for coupling to a reinforcing inorganic filler of a material, such as silica, of, for example, silanol or polysiloxane functional groups having a silanol end (such as described, for example, in FR 2 740 778 or U.S. Pat. No.

6,013,718), alkoxysilane groups (such as described, for example, in FR 2 765 882 or U.S. Pat. No. 5,977,238), carboxyl groups (such as described, for example, in WO 01/92402 or U.S. Pat. No. 6,815,473, WO 2004/096865 or US 2006/0089445) or polyether groups (such as described, for example, in EP 1 127 909 or U.S. Pat. No. 6,503,973). Mention may also be made, as other examples of functionalized elastomers, of elastomers (such as SBR, BR, NR or IR) of the epoxidized type.

[0048] A material of the compositions may contain a blend of polymers, at least one of which can be a diene elastomer. A rubber blend can include just one diene elastomer or a mixture of several diene elastomers, it being possible for the diene elastomer or elastomers to be used in combination with any type of synthetic elastomer other than a diene elastomer, indeed even with polymers other than elastomers, for example thermoplastic polymers as discussed in more detail below.

[0049] In one embodiment, the material can include a blend of diene elastomers including an isoprene elastomer in an amount of from about 75% to 100% by weight of all the diene elastomers, i.e. 75 to 100 phr (phr = parts by weight per hundred parts of rubber). As diene elastomers that may be blended with isoprene elastomers, mention can be made of any diene elastomer of the unsaturated type chosen, in in one embodiment from the group composed of polybutadienes, in particular cis-1,4 or 1 ,2-syndiotactic polybutadienes and those having a (mol %) content of 1,2-units between 4% and 80%>, and butadiene copolymers, especially styrene/butadiene copolymers, and in particular those having a styrene content between 5 and 50% by weight and more particularly between 20% and 40% by weight, a (mol %) content of 1,2-bonds of the butadiene part between 4% and 65%, a (mol %) content of trans-1,4 bonds between 30%> and 80%>, styrene/butadiene/isoprene copolymers, and blends of these various elastomers (BR, SBR and SBIR).

[0050] According to one embodiment, a diene elastomer blend can include predominantly (i.e., for more than 50 phr) an SBR, whether an SBR prepared in emulsion ("ESBR") or an SBR prepared in solution ("SSBR"), or an SBR/BR, SBR/NR (or SBR/IR), BR/NR (or BR/IR) or also SBR/BR/NR (or SBR/BR/IR) blend (mixture). In the case of an SBR (ESBR or SSBR) elastomer, use is made in particular of an SBR having a moderate styrene content, for example of between 20% and 35% by weight, or a high styrene content, for example from 35 to 45%), a content of vinyl bonds of the butadiene part of between 15% and 70%>, a content (mol %) of trans- 1,4-bonds of between 15% and 75% and a T_g of between -10 °C and -55 °C; such an SBR can advantageously be used as a mixture with a BR preferably having more than 90% (mol %) of cis- 1,4-bonds.

[0051] In another embodiment, a rubber blend can include a mixture of SBR and of BR which is used as a blend with natural rubber, for instance to a limit of less than 25% by weight (or less than 25 phr) of SBR and BR mixture.

[0052] According to another embodiment, a rubber material can include a blend of a (one or more) "high T_g" diene elastomer exhibiting a T_g of between -70 °C and 0 °C and of a (one or more) "low T_g" diene elastomer of between -110 °C and -80 °C, for instance between -105 °C and -90 °C. The high T_g elastomer can be chosen from the group including S-SBRs, E- SBRs, natural rubber, synthetic polyisoprenes (exhibiting a content (mol %) of cis- 1,4- structures greater than about 95% in one embodiment), BIRs, SIRs, SBIRs and the mixtures of these elastomers. The low T_g elastomer can include butadiene units according to a content (mol %) at least equal to 70%; for instance a polybutadiene (BR) exhibiting a content (mol %) of cis-l,4-structures of greater than 90%.

[0053] According to another embodiment, the rubber material can include, for example, from about 30 phr to about 100 phr, in particular from about 50 to about 100 phr, of a high T_g elastomer as a blend with from 0 to about 70 phr, in particular from 0 to about 50 phr, of a low T_g elastomer; according to another example, it comprises, for the whole of the about 100 phr, one or more SBR(s) prepared in solution. [0054] According to another embodiment, the diene elastomer can include a blend of a BR (as low T_g elastomer) exhibiting a content (mol %) of cis-l,4-structures of greater than 90% with one or more S-SBR(s) or E-SBR(s) (as high T_g elastomer(s)).

[0055] The diene elastomer material can include a crosslinking system based either on sulfur or on sulfur and/or peroxide and/or bismaleimide donors. In one embodiment the crosslinking system can be based on sulfur (or on a sulfur-donating agent) and on a primary crosslinking accelerator. Various known secondary accelerators or crosslinking activators, such as zinc oxide, stearic acid or equivalent compounds, or guanidine derivatives (in particular diphenylguanidine), can be included in the crosslinking system, being incorporated during the first non-productive phase and/or during the productive phase, as is known.

[0056] The sulfur can be used at a content that can vary depending upon the tire component to be formed by use of the composite. For instance, the sulfur can be used at a content of between about 0.5 and about 10 phr, for instance between about 0.5 and about 5 phr, or between about 0.5 and about 3 phr, when the composition obtained according to the invention is intended in formation of a tire tread.

[0057] Accelerators can be included to control the time and/or temperature required for crosslinking and to affect the properties of the vulcanizate. In one embodiment, a single accelerator system may be used, i.e., primary accelerator. The primary crosslinking accelerator can make possible the crosslinking of the rubber material in industrially acceptable times, while retaining a minimum safety time ("scorch time") during which the material can be shaped without risk of premature crosslinking ("scorching"). In general, the primary crosslinking accelerator can be used at a content varying from about 0.5 to about 10 phr, for instance from about 0.5 to about 5 phr, or from about 0.8 to about 1.5, phr. In another embodiment, combinations of a primary and a secondary accelerator can be used with the secondary accelerator being used in smaller amounts, such as from about 0.05 to about 3 phr. In addition, delayed action accelerators may be used which are not affected by normal processing temperatures but produce a satisfactory cure at ordinary vulcanization

temperatures. Vulcanization retarders might also be used.

[0058] Suitable types of accelerators that may be used include amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates (e.g., zinc dithiocarbamate), thiophosphates, xanthates, and combinations of accelerators. In one embodiment, the primary accelerator can be a sulfenamide. If a second accelerator is used, the secondary accelerator may be a guanidine, dithiocarbamate or thiuram compound.

[0059] Suitable accelerators of the thiazole type and their derivatives of the following formula are encompassed:

in which Ri represents a hydrogen atom, a 2-mercaptobenzothiazyl group of the following formula:

or a group of the following formula:

— NR₂R₃

in which R₂ and R3 independently represent a hydrogen atom, a 2-mercaptobenzothiazyl group, a Ci-C4 alkyl group or a Cs-Cg cycloalkyl group, for instance comprising 6 ring members in one embodiment, it being possible for said ring to comprise at least one heteroatom, such as S, O or N.

[0060] Thiazole accelerators and derivatives can be chosen from 2- mercaptobenzothiazole, 2-mercaptobenzothiazyl disulfide (abbreviated to "MBTS"), N- cyclohexyl-2-benzothiazolesulphenamide (abbreviated to "CBS"), N,N-dicyclohexyl-2- benzothiazolesulphenamide (abbreviated to "DCBS"), N-tert-butyl-2- benzothiazolesulphenamide (abbreviated to "TBBS"), N-cyclohexyl-2- benzothiazolesulphenimide, N-tert-butyl-2-benzothiazolesulphenimide (abbreviated to "TBSI") and mixtures of one or more of these compounds.

[0061] In addition to the diene elastomer(s) and a crosslinking system, a rubber material of the composition may further include all or part of the additives usually used in sulfur- cross-linkable diene rubber compositions intended for the manufacturing of tire components, such as, for example, plasticizers, pigments, antioxidants, antiozonants (e.g., antiozone waxes such as Cire^® Ozone C32 ST), vulcanization activators, aging inhibitors, softeners, extender oils, waxes, anti-degradation agents, anti-scorch agents, fatty acids, peptizers, antifatigue agents, methylene acceptors (for example phenolic novolak resin) or methylene donors (for example HMT or H3M)and so forth.

[0062] For example, particular embodiments of a rubber material for use in forming a composite may include at least one plasticizing oil extracted from petroleum of paraffinic, aromatic or naphthenic type, in a quantity of between 0 phr and 60 phr or alternatively between 0 phr and 35 phr or between 0 and 30 phr or between 0 and 20 phr or between 0 and 15 phr or between 0 and 10 phr. A plasticizing oil may include both extending oil present in the elastomers and plasticizing oil added during compounding. Suitable plasticizing oils include various oils as are known in the art, including aromatic, paraffinic, naphthenic, vegetable oils, and low polycyclic aromatic oils, such as mild extraction solvates, treated distillate aromatic extracts, SRAE and heavy naphthenic oils. Suitable low polycyclic aromatic oils include those having a polycyclic aromatic content of less than about 3 % by weight. In one embodiment, the rubber material may be totally devoid of the plasticizing oil extracted from petroleum.

[0063] Typical amounts of antioxidants comprise from about 1 to about 5 phr.

Representative antioxidants may be, for example, diphenyl-p-phenylenediamine, etc. Typical amounts of antiozonants comprise about 1 to 5 phr. Typical amounts of fatty acids, if used, which can include stearic acid comprise about 0.5 to about 3 phr. Typical amounts of zinc oxide comprise about 2 to about 5 phr. Typical amounts of waxes comprise about 1 to about 5 phr. Often microcrystalline waxes are used. Typical amounts of peptizers comprise about 0.1 to about 1 phr. Typical peptizers may be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.

[0064] A rubber material of the composite can include one or more reinforcing fillers as are known in the art. For example, one or more layers of the composite can be formed from an unfilled rubber material and one or more other layers of the composite can be formed from a filled rubber material that includes one or more reinforcing fillers that can affect various properties of the material such as, without limitation, tensile properties, flexural properties, abrasion characteristics, and so forth. Of course, two different materials of the composite can likewise both include rubber, neither of which include reinforcing fillers or alternatively both of which include reinforcing fillers.

[0065] It is possible to use any type of reinforcing filler known for its abilities to reinforce a rubber composition that can be used for manufacturing tires, for example an organic filler such as carbon black, or else an inorganic reinforcing filler such as silica, with which a coupling agent must be associated.

[0066] As carbon blacks, all the carbon blacks are suitable, especially the blacks of the HAF, ISAF, and SAF type conventionally used in tires (known as tire-grade blacks). Among the latter, mention can be made of the reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), such as for example the blacks Nl 15, N134, N234, N326, N330, N339, N347, N375, or else, depending on the targeted applications, the blacks of higher series (for example, N660, N683, N772, N900). The carbon blacks can be, for example, already incorporated into an isoprene elastomer in the form of a masterbatch (see, for example, Applications WO 97/36724 or WO 99/16600).

[0067] Inorganic reinforcing fillers are also encompassed herein. As utilized herein, the term "inorganic reinforcing fillers" (also known as a "white" filler, "clear" filler or a "non- black filler") generally refers to any inorganic or mineral filler (regardless of its color and its origin (natural or synthetic)) capable of reinforcing, by itself without any means other than an intermediate coupling agent, a rubber composition intended for manufacturing tires, in other words capable of replacing, in its reinforcing role, a conventional tire-grade carbon black; such a filler can be characterized, in one embodiment, by the presence of hydroxyl (— OH) groups at a surface.

[0068] The physical state under which a reinforcing inorganic filler is provided is not critical to the disclosed methods, whether it is in the form of a powder, of micropearls, of granules, of beads or any other appropriate densified form. Of course, the term reinforcing inorganic filler is also understood to mean mixtures of different reinforcing inorganic fillers, in particular of highly dispersible siliceous and/or aluminous fillers.

[0069] Suitable inorganic reinforcing fillers can include mineral fillers of the siliceous type, for example silica (Si0₂) or of the aluminous type, for example alumina (AI₂O₃). Silica used may be any reinforcing silica known to a person skilled in the art, especially any precipitated or fumed silica having a BET surface area and also a CTAB specific surface area that are both below about 450 m²/g, for instance from about 30 to about 400 m²/g. As highly dispersible (known as "HD") precipitated silicas, mention will be made, for example, of the silicas Ultrasil^® 7000 and Ultrasil^® 7005 from Degussa, the silicas Zeosil^® 1165 MP, 1135 MP and 1115 MP from Rhodia, the silica Hi-Sil^® EZ150G from PPG, the silicas Zeopol^® 8715, 8745 and 8755 from Huber, and the silicas having a high specific surface area such as described in Application WO 03/16837.

[0070] Reinforcing alumina used can be a highly dispersible alumina having a BET surface area from about 30 to about 400 m²/g, or between about 60 and about 250 m²/g, and/or an average particle size of about 500 nm, or about 200 nm. Non-limitative examples of such reinforcing aluminas are in particular the aluminas A125 or CR125 (from Baikowski), APA-100RDX (from Condea), Aluminoxid C (from Degussa) or AKP-G015 (Sumitomo Chemicals). In one embodiment an alumina reinforcing material can be aluminum

(oxide)hy droxides .

[0071] A person skilled in the art will understand that, as a filler equivalent to inorganic reinforcing fillers described, a reinforcing filler of another nature, for instance of an organic nature, can be used. For instance, an organic reinforcing filler can include an inorganic layer such as silica, or else can include, at its surface, functional sites, for instance hydroxyl sites, to allow the use of a coupling agent to establish a bond between the filler and the elastomer.

[0072] There may also be utilized other conventional fillers in a material of the composite, either in conjunction with the reinforcing fillers described above or without as desired. Fillers as may be included in a material of a composite can provide a reinforcing role or another role, as desired, and can include, without limitation, particles of clay, bentonite, talc, chalk, kaolin or titanium oxides, diatomaceous earth, pulverized quartz, mica, calcium silicate, magnesium silicate, glass powder, calcium carbonate, barium sulfate, zinc carbonate, and so forth.

[0073] When a composite is intended for tire treads having low rolling resistance, the inorganic reinforcing filler used in one or more of the materials of the composite, in particular when this is silica, can have a BET surface area between 45 and 400 m²/g, or between 60 and 300 m²/g in some embodiments.

[0074] The total reinforcing filler content of a material of the composite (carbon black, other types of reinforcing filler or mixture of these two types of filler) can be between 20 and 200 phr, or between 30 and 150 phr in some embodiment, the preferred amount being, in a known manner, different depending on the particular applications targeted: the level of reinforcement expected with regard to a bicycle tire, for example, is, of course, less than that required with regard to a tire capable of running at high speed in a sustained manner, for example a motorcycle tire, a tire for a passenger vehicle or a tire for a utility vehicle, such as a heavy vehicle.

[0075] An inorganic reinforcing filler can be coupled to a diene elastomer by use of an at least bifunctional coupling agent (or bonding agent) as is known. A coupling agent can provide a sufficient connection, of chemical and/or physical nature, between an inorganic filler and a diene elastomer. A coupling agent can include, for instance, bifunctional organosilanes or polyorganosiloxanes.

[0076] Use can be made in one particular embodiment of polysulfide silanes as coupling agents, said to be "symmetrical" or "asymmetrical" depending on their particular structure, such as described, for example, in applications WO 03/002648 and WO 03/002649.

[0077] Symmetrical polysulfide silanes can include, without limitation, those having the following general formula:

Z— A— S„— A— Z

in which n is an integer from 2 to 8 (e.g., from 2 to 5);

A is a divalent hydrocarbon-based radical (e.g., Ci-Cig alkylene groups or C₆-Ci2 arylene groups, for example Ci-Cio, or C1-C4, alkylenes, in particular propylene); and

Z corresponds to one of the formulae below:

^R4 ^R4 R₅

Si R4 Si R₅ Si R₅

R₅ ^R5 R₅ in which: the R4 radicals, which are substituted or unsubstituted, and identical to or different from one another, represent a Ci-Cig alkyl, C5-C18 cycloalkyl or C₆-Ci8 aryl group (e.g., Ci- C₆ alkyl, cyclohexyl or phenyl groups, such as C1-C4 alkyl groups, and in one embodiment methyl and/or ethyl); and the R₅ radicals, which are substituted or unsubstituted and identical to or different from one another, represent a Ci-Ci₈ alkoxy or C₅-Ci₈ cycloalkoxy group (e.g., chosen from Ci-Cg alkoxy and C₅-Cg cycloalkoxy groups, for example a group chosen from C1-C4 alkoxy groups, such as methoxy and ethoxy groups).

[0078] As examples of polysulfide silanes, mention can be made of disulfides, trisulfides and tetrasulfides of bis(3-trimethoxy-silylpropyl) and bis(3-triethoxysilylpropyl)

polysulphides. Among these compounds, use can be made of bis(3- triethoxysilylpropyl)tetrasulfide, abbreviated to TESPT, of formula [(C₂H₅0)₃Si(CH)₃S₂]₂ or bis(triethoxysilylpropyl)disulfide, abbreviated to TESPD, of formula [(C₂H₅0)₃Si(CH₂)₃S]₂. Mention will also be made, as examples, of the polysulfides (especially disulfides, trisulfides or tetrasulfides) of bis(mono(Ci-C₄)alkoxydi(Ci-C₄)alkyl-silylpropyl), more particularly bis(monoethoxydimethyl-silylpropyl)tetrasulfide as described in Patent Application WO 02/083782.

[0079] As a coupling agents other than a polysulfide alkoxy silanes, mention can be made of bifunctional polyorganosiloxanes and hydroxysilane polysulfides (R₅=OH in the formula above) as described in Patent Applications WO 02/30939 and WO 02/31041, or else of silanes or polyorganosiloxanes bearing azodicarbonyl functional groups, such as described, for example, in Patent Applications WO 2006/125532, WO 2006/125533 and WO

2006/125534.

[0080] A rubber material including a coupling agent can generally include the coupling agent in a content of between about 4 and about 12 phr, for instance between about 3 and about 8 phr.

[0081] A coupling agent can be pregrafted to a diene elastomer or to an inorganic reinforcing filler. In general, however, for reasons of better processing of the materials in the green state, to use the coupling agent either grafted to the inorganic reinforcing filler, or in the free state (i.e. ungrafted).

[0082] In one embodiment, one or more of the materials of the composite can include one or more thermoplastic polymers. A thermoplastic polymer can be, for example, amorphous thermoplastic polymers or semicrystalline thermoplastic polymers, the glass transition temperature of an amorphous thermoplastic polymer and the melting point of a semi- crystalline thermoplastic polymer can vary, for example from about 80 °C to about 300 °C.

[0083] Thermoplastic polymers as may be included in a material of the composite can be chosen, without limitation, from polypropylenes, polyethylenes, polystyrenes,

acrylonitrile/butadiene/styrene copolymers, polymethyl methacrylates, polyamides, polyphenylene ethers, polycarbonates, polyacetals, thermoplastic polyurethanes,

thermoplastic fluoropolymers, polyethylene terephthalates, polybutylene terephthalates, polyethylene naphthoates, and polyesters.

[0084] According to one embodiment, a material of the composite can be a rubber based material and can include a thermoplastic polymer in the form of polymeric particles. For example, polymeric particles including a thermoplastic polymer can have a volume-average diameter of less than or equal to about 200 mm, or between 50 mm and 100 about mm as may be determined with a Coulter counter as is known in the art.

[0085] When incorporated in a rubber based material, thermoplastic polymeric particles can generally be incorporated at a concentration of from about 10 to about 50 phr, or from about 20 to about 40 phr. For example, polymeric particles can represent about 20% or less, about 10% or less, by volume, with respect to the total volume of the rubber based material.

[0086] The presence in the composition of polymeric particles of thermoplastic polymers can be utilized to affect the softening of the composition during the rise in temperature, in particular in the event of braking. This can be utilized to increase the contact surface area of the tread on the ground, in particular rough ground, and thus the grip.

[0087] Of course, the inclusion of thermoplastic polymers is not limited to the form of polymeric particles, and thermoplastic materials can be incorporated into the composites and materials of the composites in any suitable form. By way of example a layer of the composite can be formed of a thermoplastic-based material, with no rubber included in the layer. In one embodiment, a layer of the composite can be a thermoplastic film. A thermoplastic film can be extruded or solution formed according to known methodology, and one or more layers of the film can be assembled with one or more layers of a rubber material according to disclosed formation methods. Of course, thermoplastic materials utilized in a composite can include fillers and additives as are known in the art.

[0088] Adhesives can also be included in a multilayer composite. An adhesive can be utilized, for instance, to improve adhesion between individual layers. Any adhesive as is known in the art can be utilized, with preferred adhesives generally depending upon the layers on either side of the adhesive layer.

[0089] By way of example, in one embodiment, an adhesive layer can include an unsaturated thermoplastic styrene (TPS) copolymer as described in U.S. Patent No. 8,679,608 to Lesage, et al, which is incorporated herein by reference, a TPS copolymer adhesive can include styrene blocks and diene blocks, these diene blocks being in particular isoprene or butadiene blocks. In general, an adhesive layer can include about 50 phr or more of the TPS copolymer, for instance about 70 phr, or from about 80 phr to about 100 phr.

[0090] Unsaturated TPS elastomers such as, for example, SBS, SIS or SBBS are well known and are commercially available, for example from Kraton under the tradename Kraton D^® (e.g., products Dl 161, Dl 118, Dl 116, Dl 163 for examples of SIS and SBS elastomers), from Dynasol under the tradename Calprene^® (e.g., products C405, C411, C412 for examples of SBS elastomers) and from Asahi under the tradename Tuftec^® (e.g., product PI 500 for an example of an SBBS elastomer).

[0091] An adhesive layer may optionally comprise, depending on the particular applications employed, a liquid plasticizing agent (which is liquid at ambient temperature, i.e. 23 °C), which can plasticize the TPS copolymer and thus give more flexibility to

the adhesive layer. A liquid plasticizing agent may consist of an extender oil as described within, for instance a polybutene oil such as polyisobutylene oil, paraffinic oils and mixtures of these oils. A liquid plasticizing agent can be present at a content between 0 and 100 phr, for instance between 5 and 50 phr, or within a range from 10 to 40 phr.

A liquid elastomer may also be utilized as a plasticizing oil, that is to say an elastomer having a low number average molecular weight, typically about 50,000 or less, for instance about 30 000 g/mol or less.

[0092] Other suitable adhesives as are known in the art may be utilized including, without limitation, pressure sensitive adhesives, repositionable adhesives, thermosetting adhesives, and combinations of any two or more thereof. For instance, stabilized cyanoacrylate adhesives, and stabilized cyanoacrylate adhesives as disclosed in U.S. Patent No. 6,642,337 to Misiak, et al. and U.S. Pat. No. 5,530,037 to McDonnell, et al. and incorporated by reference herein may be utilized.

[0093] Epoxy adhesives as are known in the art may be utilized including, without limitation, mono functional epoxides (e.g., phenyl glycidyl ether, cresyl glycidyl ether, and glycidyl ethers of alcohols (e.g., dodecyl alcohol)), multifunctional epoxides (e.g., epoxides of polyunsaturated organic compounds, oligomers of epihalohydrins, glycidyl derivatives of hydantoin and hydantoin derivatives, glycidyl ethers of polyvalent alcohols, glycidyl derivatives of triazines, and glycidyl ethers of polyhydric phenols (e.g., glycidyl ethers of dihydric phenols, including resorcinol, hydroquinone, bis-(4-hydroxy-3,5-difluorophenyl)- methane, 1 , 1 -bis-(4-hydroxyphenyl)-ethane, 2,2-bis-(4-hydroxy-3-methylphenyl)-propane, 2,2-bis-(4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis(4-hydroxyphenyl)-propane (i.e., bisphenol A), and bis-(4-hydroxyphenyl)-methane (i.e., bisphenol F, which may contain varying amounts of 2-hydroxyphenyl isomers)), cycloaliphatic epoxy resins, epoxy novolac resins (i.e., glycidyl ethers of novolac resins), and combinations thereof. [0094] Fibrous materials can be included in the composites. For instance, a polymeric layer can include fibers as reinforcing filler in the polymeric matrix, e.g., a rubber based material and/or a thermoplastic based material can include a fibrous filler. Fibrous materials can also encompass woven or non- woven materials, which can be incorporated as a layer of a multilayered composite.

[0095] Reinforcing fibers can be metal fibers (e.g., stainless steel fibers), metallized inorganic fibers, metallized synthetic fibers, graphite fibers, polymer fibers, or a combination thereof. Non-limiting examples of fibrous fillers include inorganic fibers, including processed mineral fibers such as those derived from blends comprising at least one of aluminum silicates, aluminum oxides, magnesium oxides, and calcium sulfate hemihydrate, boron fibers, ceramic fibers such as silicon carbide, and fibers from mixed oxides of aluminum, boron and silicon sold under the trade name NEXTEL^® by 3M Co., St. Paul, Minn., USA. Also included among fibrous fillers are single crystal fibers or "whiskers" including silicon carbide, alumina, boron carbide, iron, nickel, and copper. Fibrous fillers such as carbon fibers, glass fibers (e.g., lime-aluminum borosilicate glass that is soda-free ("E" glass), A, C, ECR, R, S, D, or NE glasses), basalt fibers, including textile glass fibers and quartz can also be included for purposes of this disclosure.

[0096] Organic reinforcing fibrous fillers and synthetic reinforcing fibers can be used. This includes organic polymers capable of forming fibers such as polyethylene terephthalate, polybutylene terephthalate and other polyesters, polyarylates, polyethylene, polyvinylalcohol, polytetrafluoroethylene, acrylic resins, high tenacity fibers with high thermal stability including aromatic polyamides, polyaramid fibers such as Kevlar (product of Du Pont), polybenzimidazole, polyimide fibers such as polyimide 2080 and PBZ fiber (both products of Dow Chemical Company); and polyphenylene sulfide, polyether ether ketone, polyimide, polybenzoxazole, aromatic polyimides or polyetherimides, and the like. Combinations of any of the foregoing fibers can also be used.

[0097] Reinforcing fibers generally can have an elastic modulus higher than 10

GigaPascals (GPa). Fibers can be provided in the form of monofilament or multifilament fibers; non-woven fibrous reinforcements such as continuous strand mat, chopped strand mat, tissues, papers, and felts or the like. In one embodiment, the reinforcing fibers can be discontinuous, in the form of single discrete fibers within a polymeric matrix. Where glass fibers are used and are provided in the form of chopped strand bundles, the bundles can be broken down into single fibers before the material is formed. Fiber sizes can vary as is known in the art. In one embodiment, discontinuous reinforcing fibers can be about 5 to about 75 millimeters (mm) in the longest dimension, for instance about 6 to about 60 mm, or about 7 to about 50 mm in the longest dimension. Shorter fibers of a length less than about 5 mm are also encompassed. In one embodiment, the fibers can have a length of from about 3 mm to about 5 mm. In another embodiment, the fibers can be continuous fibers. Fiber diameters can vary depending upon the particular fiber used. Discontinuous reinforcing fibers can have a diameter of about 5 to 125 micrometers (μιη), or about 10 to about 100 μιη in one embodiment. The fibers, for instance, can have a diameter of less than about 100 μιη, such as less than about 50 μιη. For instance, the fibers can be chopped or continuous fibers and can have a fiber diameter of from about 5 μιη to about 50 μιη, such as from about 5 μιη to about 15 μιη.

[0098] Fibrous fillers can exist in the form of whiskers, needles, rods, tubes, strands, elongated platelets, lamellar platelets, ellipsoids, micro fibers, nanofibers and nanotubes, elongated fullerenes, and the like. Where such fillers exist in aggregate form, an aggregate can have an aspect ratio greater than 1.

[0099] Fiber types can be used either alone or in combination with other types of fiber, through, for example, co-weaving or core/sheath, side-by-side, orange-type or matrix and fibril constructions, or by other methods known to one skilled in the art of fiber manufacture. Typical co-woven structures include glass fiber-carbon fiber, carbon fiber-aromatic polyimide (aramid) fiber, and aromatic polyimide fiber-glass fiber. Fibrous fillers can be supplied in the form of, for example, rovings, woven fibrous reinforcements, such as 0-90 degree fabrics, non-woven fibrous reinforcements such as continuous strand mat, chopped strand mat, tissues, papers and felts and 3-dimensionally woven reinforcements, performs and braids. In general the amount of fibrous filler present in the nanocomposite can range anywhere from about 0 to about 50 wt. % based on the total weight of the composition, preferably from about 0 to about 20 wt. % thereof.

[00100] Fibers may be pretreated with a sizing as is generally known. In one embodiment, the fibers may have a high yield or small K numbers. A tow is indicated by the yield or K number. For instance, glass fiber tows may have 50 yield and up, for instance from about 115 yield to about 1200 yield. [00101] The rubber layers of the composite can be manufactured in suitable mixers, using two successive preparation phases well known to a person skilled in the art: a first phase of thermomechanical working or kneading (sometimes referred to as a "non-productive" phase) at high temperature, up to a maximum temperature (denoted by T_max) between 110 °C and 190 °C, for instance between 130 °C and 180 °C, followed by a second phase of mechanical working (sometimes referred to as a "productive" phase) at a lower temperature, typically below 110 °C, for example between 40 °C and 100 °C, a finishing phase during which the crosslinking or vulcanization system is incorporated. Such phases have been described, for example, in Applications EP-A-0501227, EP-A-0735088, EP-A-0810258, EP-A-0881252, W099/28376, WO00/05300, WO00/05301 or WO02/10269.

[00102] A process for manufacturing a rubber material includes a step of incorporating into a diene elastomer, during a first so-called "non-productive" step, one or more additives by thermomechanically kneading the whole mixture, in one or more goes, until a maximum temperature between 110 °C and 190 °C is reached. Additives as may be incorporated during a non-productive step can include processing aids, aging inhibitors, fatty acids, etc. In those materials in which the rubber is filled with a reinforcement filler, the reinforcement filler can be incorporated with the rubber during the non-productive step. The total kneading time, in this non-productive phase, is generally between 2 and 10 minutes.

[00103] The mixture can be cooled following the non-productive phase to a temperature below 100 °C. Following cooling, during a second "productive" step, the crosslinking or vulcanization system can be added. This mixture is then kneaded to a maximum temperature that is below 120 °C. The productive phase mixing can be carried out for a few minutes, for example between 5 and 15 minutes. Finally, the mixture is extruded, milled, or calendered to form a sheet-like material for combination with other materials as disclosed herein.

[00104] As previously mentioned, layers of the composite can include rubber based layers as well as layers of other formation materials. For instance, a thermoplastic based polymeric layer in the form of a polymeric film, sheet, nonwoven, or woven layer can be included in a composite. For example, a layer in the form of a nonwoven mat formed of fibers, e.g., melt blown fibers, can be incorporated into a composite. A melt-blowing process can include extruding a polymeric composition from an extruder through a linear array of single- extrusion orifices directly into a high velocity heated air stream. The rapidly moving hot air greatly attenuates the fibers as they leave the orifices. The impinging high- velocity hot air attenuates the filaments and forms the fibers. The discontinuous fibers may be deposited on a conveyor or takeup screen to form a random, entangled web that may be incorporated into a composite as described herein.

[00105] According to another embodiment, a layer of the composite can include electrospun fibers, for instance in the form of a nonwoven web. An electrospun formation process can be utilized to form high surface area webs of small fibers have a diameter of less than about 100 nm, less than about 50 nm, or less than about 20 nm in some embodiments. An electrospinning process can form the nano-sized fibers from a solution or a melt, generally depending upon the particular polymer to be utilized.

[00106] The standard process for electrospinning can include a spinneret connected to a high-voltage (5 to 50 kV) direct current power supply, a syringe pump, and a grounded collector. A polymer solution, sol-gel, particulate suspension or melt is loaded into the spinneret and this liquid is extruded from the needle tip at a constant rate by a syringe pump. Alternatively, the droplet at the tip of the spinneret can be replenished by feeding from a header tank providing a constant feed pressure.

[00107] The critical field strength required to overcome the forces due to surface tension of the solution/melt and form a jet will depend on many variables of the system. These variables include not only the type of polymer and solvent, but also the solution concentration and viscosity, as well as the temperature of the system. In general, characterization of the jet formed, and hence characterization of the fibers formed, depends primarily upon

solution/melt viscosity, net charge density carried by the electrospinning jet and surface tension of the solution.

[00108] To form the composites, two or more layers can be assembled. For instance, one or more rubber based layers and one or more layers of a second formation material (e.g., a different rubber material, a thermoplastic based material, etc.) can be coextruded to form a multilayered assembly. In another embodiment, a layer (e.g., a nonwoven mat) can be formed directly on to a previously formed rubber based layer. Alternatively, the different layers can be formed individually and then assembled. Combinations of formation and assembly can be encompassed as well, with some layers being directly formed on the assembly and other layers (e.g., layers that include multiple different formation materials) being formed prior to the assembly. The thickness of the initial layers can be of any suitable size. For instance, the initial layers can be about 0.5 mm or greater, such as from about 0.5 mm to about 10 mm, or from about 1 mm to about 5 mm in some embodiments. It will be understood, however, that the particular thickness of a layer can depend upon the formation material, for instance, and adhesive layer may be quite thin as compared to other layers.

[00109] Following assembly, the multilayered structure can be compressed and the original thickness of the assembled layers can be decreased by the compressing. In one embodiments, the compressing can also bond the individual layers to one another, for instance in those embodiments in which layers have not been previously bonded to one another. The number of compressing steps and the compression of each steps can be controlled so as to control the structuring of the final product including the average number of layers per millimeter thickness of the final product and the continuity or discontinuity of materials throughout the final product. Compressing methods can include any form of compressing as may be utilized to decrease the overall thickness of the assembled layers and optionally bond individual layers to one another. For instance, a milling process (i.e., sending two or more layers through a nip formed between two rolls so as to compress the layers) can be used. A milling process can be a continuous process and can include one nip or several nips in series with one another, as desired. The space between the two rolls that form a nip can be utilized in controlling the thickness decrease of a compressing step. Other compressing methods can include a plate press, in which the assembled layers are subjected to compression between two plates or platens; a stamping process; and so forth. Optionally, a compressing step can be carried out in conjunction with the application of heat. For instance, the assembled layers can be compressed between heated rolls in a milling process or heated plates. However, when heat is applied during the compressing of the assembly, the temperature of the rubbers of the assembly should be maintained below vulcanization conditions.

[00110] The compressing step(s) can be controlled to control the final microstructuring of the formed composite. For instance, through control of the compressing (e.g., number of compressing steps, amount of compression obtained at each step, etc.), the final product can include continuous layers across the width of the composite, or alternatively one or more formation materials of the composite can form discontinuous layers across the width of the composite, as the compressing in one or more of the steps can cause breaks to form in the layer(s) of the materials during the compressing. [00111] The assembly and compressing steps can be repeated one or more times to form a composite. By way of example, following a first pressing, the thus formed multilayered composite can be cut into pieces and those pieces, each of which being a multilayered composite, can be assembled together. Alternatively, the initial multilayered composite can be folded over on itself one or more times to assemble multiple multilayered composites and this assembly can then be subjected to one or more compressing steps.

[00112] The multilayered composites that are assembled need not be identical to one another. For instance one or more multilayered composites that differ from one another with respect to some aspect can be assembled, optionally in conjunction with multilayered composites that are the same as one another, and this assembly can then be subjected to compressing. In addition, one or more multilayered assemblies can be assembled with layers that have not been previously compressed, as discussed previously.

[00113] A formation process can be a continuous process in which a first compressing step is carried out, the compressed materials are folded one or more times, and/or otherwise assembled in conjunction with other layers, and the new assembly is compressed. This process can be repeated until the final desired formation is attained. Moreover, subsequent compressing steps can be the same as one another or can vary, for instance with regard to the percentage of thickness decrease of the assembly that is obtained in each compressing step.

[00114] Through variations in materials utilized, layer patterns, and number of repetitions of the layering and compressing processes, multilayered composites can be formed with a variety of structures. For instance, individual materials of the composites can be in the form of continuous or discontinuous layers across the composite materials. In addition, the layers of the formed composites can have a controlled thickness. For instance, individual layers of a formed composite can be about 100 μιη or less, about 50 μιη or less, about 20 μιη or less, about 10 μιη or less or in the nanometer range, for instance about 500 nm or less, about 400 nm or less, or about 200 nm or less. For instance, individual layers of the composite can have a thickness of from about 100 nm to about 100 μιη, from about 200 nm to about 100 μιη, from about 1 μιη to about 100 μιη or from about 10 μιη to about 50 μιη, in some

embodiments. Of course, individual layers of a composite can be outside of this range. For instance, an adhesive layer that includes only an adhesive between adjacent layers, may be less than 100 nm in thickness following compressing. Other layers likewise can be quite small and less than 100 nm in thickness. Likewise, a formed composite can have one or more thicker layers within the composite. For instance, the formed composite can have a layer with a thickness greater than about 100 μιη, and this thicker layer can be sandwiched between other, thinner layers or alternatively can be an outer layer of a composite. The composite can similarly have several thicker layers with one or more thinner layers on one or both sides of the thicker layers. In general, and as discussed above, the formed composite can have an average number of layers per millimeter of thickness of about 20 or more.

[00115] Vulcanization (or curing) of the rubber of the multilayerd composite can be carried out according to standard practice following formation of the final composite product. For instance, rubber of the formed multilayered composite can be vulcanized at a temperature generally between 130 °C and 200 °C for a sufficient time which may vary, for example, between 5 and 90 minutes depending, in particular, on the curing temperature, the

vulcanization system used, the vulcanization kinetics of the composition in question or, for example, the size (e.g., thickness) of the layered material.

[00116] The composite materials can be utilized in forming any of a variety of different tire components including, without limitation, a tread, undertread, sidewall, wire skim, inner liner, bead, apex, any compound used in a tire carcass, including carcass reinforcement and in other components for tires. For instance, a multilayered composite can be assembled with other materials to form a tire component or to combine tire components. By way of example, a multilayered composite can be assembled adjacent to another component of the tire component. In one embodiment, a multilayered composite can be assembled such that it is sandwiched between two other tire components as is known in the art.

[00117] Particular embodiments of the present invention include components intended for passenger-car or light truck tires but the disclosure is not limited only to such tires. It is noted that the particular embodiments of the components of the present disclosure are intended to be fitted on motor vehicles or non-motor vehicles such as bicycles, motorcycles, racing cars, industrial vehicles such as vans, heavy vehicles such as buses and trucks, off- road vehicles such as agricultural, mining, and construction machinery, aircraft or other transport or handling vehicles.

[00118] The present disclosure may be better understood with reference to the examples set forth below.

Example 1 [00119] Two rubber formulations were prepared. The formulations are described in the table below. Amounts are provided in parts by weight per hundred parts of rubber (phr).

[00120] Formulations of Mix A and Mix B were separately milled between two rolls to 1 mm skims using a standard milling process. The milling machine included an upper roll heated to 60 °C to avoid sticking to Mix B (which had a high T_g) and the lower roll was heated to 40 °C to avoid bad aspect with the low T_g Mix B. The rolls were operated at an identical, no friction low speed. The nip of the mill was decreased each pass by from about 0.1 to about 0.4 mm for layers that were from about 2 to about 4 mm in thickness and from about 0.2 to about 0.7 mm for layers that were from about 4 to about 20 mm in thickness.

[00121] Rectangular samples of each milled mix were cut to a size of 1 mm x 20 cm x 60 cm. Sixteen bi-layered composites were formed by assembling one skim of Mix B with one skim of Mix A. The resulting bi-layered assembly had a composite thickness of 2 mm. The thickness of each bi-layered composite was reduced by passing it several times through the milling process. Eight 4-layered composites were prepared by combined two of the bi- layered composites following thickness reduction. The composites were combined to have a Mix A layer alternated with a Mix B layer. The thickness of each 4-layered composite was reduced by passing it several times through the milling rolls.

[00122] Two 16-layered composites were then formed. To form the 16-layered composites, four of the 4-layered composites were combined and the thickness of the 16- layered composites was reduced in the milling process.

[00123] Each of the 16-layered composites was cut in four equal pieces. Two 32-layered composites were formed by assembling two 16-layered composites together. The thickness of the 32-layered composites was then reduced by passing through the milling system several times. The compressed 32-layered composites were cut into four equal pieces and two 64- layered composites were formed by assembling together two 32-layered composites and reducing the thickness of the assemblies.

[00124] The 64-layered composites were cut and two 128-layered composites were formed and the thicknesses reduced by use of the milling system. Thickness of each of the 128- layered composites was reduced to about 2.1 mm by passing it several times through the milling system.

[00125] The rubber of the resulting composite was then cured for 40 minutes at 150 °C.

[00126] Both optical and scanning electron microscopy images were performed on the resulting samples. FIG. 3, FIG. 4 and FIG. 5 present images of increasing magnification of the resulting composites.

Example 2

[00127] Two rubber formulations were prepared. The formulations are described in the table below. Amounts are provided in parts by weight per hundred parts of rubber (phr).

Silica - 50.00

Coupling agent - 5.00

Anti-scorch agent - 0.50

Total 109.40 168.23

[00128] The two mixes were calendered to form 1 mm skims. 150 mm x 150 mm squares were punched out of the skims.

[00129] The following pattern was used to form a first multilayered composite

(Representative Example 1):

C-D-C-C-D-C-C-D-C

[00130] The following pattern was used to form a second multilayered composite

(Representative Example 2):

D-C-D-D-C-D-D-C-D

[00131] The multilayered composites thus formed were placed between two Teflon^® films and placed in a plate press. The plate press was set to 1 minute at 120 °C and 40 tons of pressure. The multilayered structures were allowed to sit in the press without pressure for 1 minute to warm up. Following, pressure was applied and then placed on a cold surface to cool down. The compressed sample was then removed from the Teflon^® films.

[00132] The compressed sample was then cut into four equal sectors. The four sectors were stacked on top of one another. This multilayered assembly was placed into the press for 1 minute without pressure to warm up. The assembly was then compressed again. The cutting, assembly, and compression steps were repeated twice more.

[00133] FIG. 6 presents a microscopic image of the final product formed of the

Representative Example 1 (C-D-C-C-D-C-C-D-C) and FIG. 7 presents a microscopic image of the final product formed of the Representative Example 2 (D-C-D-D-C-D-D-C-D). The darker material is the softer Mix A of the composites. As can be seen, the Mix B component of the composites is discontinuous across the composite.

[00134] Two comparative rubber formulations were prepared. Comparative Example 1 included a standard combination and vulcanization of components as were utilized in forming Representative Example 1 (i.e., the total amount of components used in forming the entire multilayered composite of Representative Example 1). Comparative Example 2 included a standard combination and vulcanization of components as were utilized in forming Representative Example 2 (i.e., the total amount of components used in forming the entire multilayered composite of Representative Example 2).

[00135] FIG. 8 graphically illustrates the friction coefficient for Comparative Example 1, Comparative Example 2, Representative Example 2, and Representative Example 1. As can be seen Representative Example 1 composite shows a 36% improvement over the

Comparative Example 1 that was formed of the same materials, and the Representative Example 2 composite shows a 20% improvement over the Comparative Example 2 that was formed of the same materials.

[00136] While the present subject matter has been described in detail with respect to specific example embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.

Claims

WHAT IS CLAIMED IS:

1. A tire component comprising a multilayered composite having a thickness and including 20 or more layers adhered to one another, the multilayered composite comprising an average number of layers per millimeter of the thickness of 20 or more, wherein at least one of the layers comprises a first formation material that includes a rubber and wherein at least one other layer comprises a second formation material, other layers when present independently comprising at least one of the first formation material and/or the second formation material and/or one or more other formation materials, the formation materials differing from one another according to a mechanical property, chemical property, optical property, electronic property, or combination thereof.

2. The tire component of claim 1, the multilayered composite comprising an average number of layers per millimeter of thickness of from 100 to 2,000, or from 250 to 1,500, or from 500 to 1,000.

3. The tire component of claim 1 or claim 2, wherein the rubber is an essentially unsaturated diene elastomer.

4. The tire component of any of the preceding claims, wherein at least one of the layers is a discontinuous layer.

5. The tire component of any of the preceding claims, wherein one or more of the formation materials comprises a reinforcing filler.

6. The tire component of any one of the preceding claims, wherein one or more of the formation materials comprises at least one of a fiber and/or a thermoplastic polymer.

7. The tire component of claim 6, wherein one or more of the formation materials comprises a woven or nonwoven material.

8. The tire component of any of the preceding claims, wherein one or more of the formation materials comprises an adhesive.

9. The tire component of any of the preceding claims, wherein the second formation material and/or one or more other formation materials comprise an additional rubber that is the same or different from the rubber of the first formation material.

10. The tire component of any of the preceding claims, wherein at least one of the layers includes multiple formation materials.

11. The tire component of claim 10, wherein the multiple formation materials are arranged in a pattern selected from random, geometric, or combinations in the at least one layer.

12. The tire component of any of the preceding claims, wherein the formation materials have a regular distribution across the thickness of the multilayered composite.

13. The tire component of any of claims 1 through 11, wherein the formation materials an irregular distribution across the thickness of the composite.

14. The tire component of any of the preceding claims, wherein the tire component is a tread, an undertread, a sidewall, a wire skim, an inner liner, a bead, an apex, or a carcass reinforcement.