Use of carbon nanofiber-containing carbon networks

Abstract

The present invention relates to the use of porous, chemically interconnected carbon nanofiber-containing carbon networks to reinforce elastomers. The carbon nanofiber-containing carbon networks are advantageous when added to elastomers, particularly styrene-butadiene rubber (SBR), at 10-120 phr. Benefits include low tan δ (rolling resistance) at 60°C, high tan δ (wet grip) at 0°C, good abrasion resistance, high flexibility, and low stiffness. Reinforced elastomers can be used in many technical fields, such as tires, conveyor belts, and hoses.

Description

[Technical Field]

[0001] The present invention relates to the field of elastomer reinforcement, in particular to the field of reinforcement of tires or industrial rubber products.

[0002] Elastomers are widely used in many technical applications, such as tires, sealing systems, belts in conveyor systems, etc., hoses, automotive weatherstripping, molded rubber products, etc. The elastomer market can be subdivided into tires and industrial rubber products, where the important rubber components of commodity compounds are nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), ethylene propylene diene monomer rubber (EPDM) and / or natural rubber, and the important rubber components of high performance compounds are vinylidene fluoride monomer rubber (FKM), perfluoro-elastomer (FFKM), tetrafluoroethylene / propylene rubber (FEPM) and / or hydrogenated nitrile butadiene rubber (HNBR).

[0003] Elastomeric end products, such as tires, often contain various rubbers, each blended with chemical and structural components to impart desired properties to the end product. For example, a typical automobile tire may contain approximately 45% by weight elastomer (e.g., natural rubber, styrene-butadiene rubber (SBR), polybutadiene rubber (BR), and butyl rubber), approximately 20% reinforcing agent (e.g., carbon black and / or silica), approximately 15% metal, approximately 5% textile, and various additives, such as zinc oxide, sulfur, and others. Tires, such as automobile tires, may contain 30 to 90 phr or more of carbon black. EP 2 880 090 A1 describes the beneficial use of specific ratios of natural rubber, nanocarbon, and carbon black reinforcing agent to improve tire properties.

[0004] Furthermore, industrial rubber products (conveyor belts, fuel hoses) usually contain large amounts of reinforcing agents, such as carbon black and / or silica. In this case, a requirement may arise to prevent the buildup of static electricity, which can occur when two non-conductive materials move relative to one another. The discharge of said static charge can lead to various problems or hazards, including malfunctions of electronic equipment or fires. These risks can be prevented by including carbon black, thereby making at least one of the materials (semi-)conductive. Sealing systems also usually contain carbon black. In this case, a smooth surface is a requirement. To obtain the best possible seal, surface imperfections must be avoided or at least minimized.

[0005] In current technology, carbon black is the predominant reinforcing agent because it is cost-effective and improves the processability of elastomers. Much research has been directed toward tailoring carbon black to obtain optimal results in the final product. This has led to a variety of carbon blacks with different average particle sizes, specific surface areas, porosities, impurity contents, etc. There remains a need to further improve elastomer performance and identify technologies that allow for the mass production of improved elastomers at an acceptable price.

[0006] In research to optimize the properties of elastomer end products, it has been found that incorporating certain technologically advanced products, such as carbon nanotubes, as additives can improve the properties of elastomers. For example, International Publication No. 2016 / 045960 describes the use of nano-sized carbon structures (nanocarbons, e.g., carbon nanotubes) in the preparation of reinforced (filled) styrene-butadiene rubber (SBR). However, these materials are difficult to produce on a large scale. In many cases, these materials are difficult to disperse or are incompatible with some other ingredients. To make them effective in an industrial environment, specialized equipment is required, further impairing throughput.

[0007] US Patent Application Publication No. 2017 / 369660 describes carbon nanotube-elastomer composites, methods for producing the composites, and their use as encapsulants. It mentions a network of tubes that are physically connected by percolation.

[0008] There is a need to further develop the properties of elastomers that can be mass-produced in a cost-effective manner to obtain better and higher performance end products. There is a need to produce automobile tires with lower rolling resistance to reduce fuel consumption and meet environmental challenges while maintaining essential tire properties. There is also a need to improve the wet grip or snow performance of tires while maintaining constant rolling resistance and service life.

[0009] Similarly, there is a need for improved elastomers to produce conveyor belts with lower rolling resistance to reduce power consumption, and belts with high damage resistance to prevent downtime due to cuts, abrasions, wear, and ruptures. Also, in the field of sealing systems, there is a need for better sealing systems that provide better sealing properties and improved compression performance (i.e., operational life) of rubber compounds. Summary of the Invention

[0010] The present inventors have discovered that the use of recently developed carbon nanofiber-containing carbon networks can improve the properties of elastomers to an extent that can satisfy the aforementioned need in the art. More specifically, it has been discovered that porous, chemically interconnected carbon nanofiber-containing carbon networks can be used to reinforce elastomers. See the Examples herein. It has been discovered that these porous, chemically interconnected carbon nanofiber-containing carbon networks, which have high intraparticle porosity, can be used to produce highly reinforced elastomers. While not wishing to be bound by theory, this is believed to be due to the intraparticle pores of these networks. The strength of the elastomer can be improved without the usual drawbacks, such as reduced tan δ (wet grip) at 0°C and / or increased tan δ (rolling resistance) at 60°C and / or increased deformation (creep) with increasing temperature. The reinforced elastomer composites of the present invention are highly useful in many technical applications, such as tires or industrial rubber products, such as sealants, gaskets, conveyor belts, tubing, etc. This allows tires, such as car tires or conveyor belts, to be produced that have lower rolling resistance without compromising wet grip or product life.

[0011] The carbon network may include crystalline carbon nanofibers. The carbon nanofibers may have a length of 30 to 10,000 nm. Furthermore, the carbon network has intra-particle pores. The carbon network of the present invention can be added to an elastomer in a content of 1 to 60 wt % or 10 to 120 phr.

[0012] The invention also extends to the preparation of said carbon networks by reduced (pyrolysis) or oxidized (semi- or fully burned) carbon black preparation methods, primarily using conventional kits. [Brief explanation of the drawings]

[0013] [Figure 1A]FIG. 1A is a schematic diagram of a continuous furnace carbon black production process according to the present invention, comprising a reactor 3 along its axis, a combustion zone 3a, a reaction zone 3b, and an end zone 3c, in which a fuel a is combusted in an oxygen-containing gas b, the waste gas a1 is transferred from the combustion zone 3a to the reaction zone 3b, thereby generating a flow of hot waste gas a1 in the combustion zone, a single-phase emulsion c is sprayed (atomized) into the reaction zone 3b containing the hot waste gas, the emulsion is carbonized at a high temperature, and the reaction is quenched or stopped in the end zone 3c by spraying water d to obtain a crystalline carbon network e according to the present invention. [Figure 1B] 1B is a schematic diagram of a semi-batch carbon black production process in which single-phase emulsion c is atomized at high temperature through nozzle 4 at the top of reactor 3 into reaction zone 3b, where the emulsion is carbonized at high temperature, and a crystalline carbon network e is recovered at the bottom of the reactor. Additionally, there are two gas inlets into the reactor from the top for adding an inert gas f, preferably nitrogen, for controlling and / or depleting oxygen concentration, and for introducing a carbon-containing gas g, preferably acetylene or ethylene, into the reactor.

[0014] Aspects of the invention 1. Use of porous, chemically interconnected carbon nanofiber-containing carbon networks to reinforce elastomers. 2. Use according to embodiment 1, wherein the content of the carbon network in the reinforced elastomer is 1 to 60 wt. % or 10 to 120 phr. 3. The use of embodiment 1 or 2, wherein the carbon network comprises crystalline carbon nanofibers. 4. The use of any one of the preceding aspects, wherein the carbon network is an intra-particle porous network. 5. The use of any one of the preceding aspects, wherein the carbon nanofibers have an average fiber length of 30 to 10,000 nm. 6. The use of any one of the preceding aspects, wherein the reinforced elastomer is used in a tire or industrial rubber product. 7. A reinforced elastomer comprising 10 to 120 wt. % or 10 to 120 phr of a porous, chemically interconnected carbon nanofiber-containing carbon network. 8. The use of any one of aspects 1 to 6 or the reinforced elastomer of aspect 7, wherein the reinforced elastomer meets at least four, more preferably at least five, even more preferably at least six, and most preferably all of the following characteristics according to aspect (a) in the table:

[0015] [Table A]

[0016] 9. The use of any one of embodiments 1 to 6 and 8, or the reinforced elastomer of any one of embodiments 7 to 8, wherein the carbon network is obtainable by a process using a reactor 3 comprising a reaction zone 3b and a termination zone 3c, comprising injecting a water-in-oil or bicontinuous microemulsion c comprising metal catalyst nanoparticles into the reaction zone 3b at above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100°C, preferably at most 3000°C, more preferably at most 2500°C, and most preferably at most 2000°C to obtain a crystalline carbon network e, transferring the network e to the termination zone 3c, and spraying water d into the termination zone to quench or stop the formation of the crystalline carbon network. 10. An article comprising the reinforced elastomer of any one of embodiments 7-9. 11. The article of embodiment 10, which is a tire or an industrial rubber product.

[0017] Detailed Description In a first aspect, the present invention can be described as the use of a porous, chemically interconnected carbon nanofiber-containing carbon network (i.e., a porous carbon network comprising chemically interconnected carbon nanofibers) to reinforce an elastomer. Those skilled in the art will understand that a porous network refers to a three-dimensional structure that allows liquids or gases to pass through.

[0018] The porous network may also be referred to as a porous medium or a porous material. The pore volume of the porous carbon network according to the present invention is between 0.1 and 1.5 cm3 as measured by the Brunauer, Emmett, and Teller (BET) method (ASTM D6556-09). 3 / g, preferably 0.2 to 1.5 cm 3 / g, more preferably 0.3 to 1.3 cm 3 / g, most preferably 0.4 to 1.3 cm 3 / g.

[0019] The porous carbon network (or porous carbon network particle) according to the present invention can be considered as a large molecule in which carbon atoms are interconnected essentially by covalent bonds. Here, it is understood that porous carbon network particles are particles containing chemically interconnected (i.e., covalently bonded) fibers with intraparticle pores, as opposed to interparticle pores, which are referred to as a porous network created by multiple molecules or particles, where the pores are formed by the spaces between physically aggregated particles or molecules. Because the carbon network particle according to the present invention can be considered as a large molecule in which the pores are embedded, the intraparticle pores in the present invention may also be understood as intramolecular pores. Therefore, the terms intraparticle pores and intramolecular pores have the same meaning herein and may be used interchangeably when describing the porous network of the present invention. Compared to traditional carbon black, which does not have an intraparticle porous structure within the carbon black particle, aggregates of carbon black particles can have interparticle porous properties. Interparticle-intermolecular refers to the space between physically aggregated particles (network), while intraparticle-interparticle refers to the space within the network itself.

[0020] Without being bound by theory, it is believed that the benefit of having a network with intra-particle pores over a network with inter-particle pores is that the latter is more robust and more resilient to fracture and breakage when force is applied. Intra-particle pores refer to pores present inside the (nano)particles. Inter-particle pores refer to pores resulting from the stacking of individual particles. Inter-particle pores are weak and prone to collapse due to particle-particle interfaces. Intra-particle pores are strong due to the covalently bonded structure surrounding them and can withstand large forces and high pressures without collapsing.

[0021] As mentioned above, known reinforcing agents, such as carbon black, consist of aggregates or agglomerates of spherical particles, which may form a three-dimensional structure without covalent bonds between the individual particles (without being "chemically interconnected"), and therefore have inter-particle pores. In summary, intra-particle pores refer to the state in which the carbon atoms surrounding the pores are covalently bonded, and inter-particle pores refer to the pores that exist between particles that are physically aggregated, aggregated, etc.

[0022] The networks of the present invention can be considered one large molecule, and therefore do not require the particles or portions of the network to be fused together. Thus, the porous network of chemically interconnected carbon nanofibers is a carbon network containing unfused, intraparticle-porosity, chemically interconnected carbon nanofibers. In preferred embodiments, the intraparticle pore volume can be characterized, for example, with respect to mercury intrusion porosimetry (ASTM D4404-10) or the Brunauer, Emmett, and Teller (BET) method (ISO 9277:10), as further described below.

[0023] Those skilled in the art will readily understand that the term "chemical interconnection" in the context of a porous, chemically interconnected carbon nanofiber-containing carbon network refers to a state in which carbon nanofibers are interconnected with other nanofibers through chemical bonds. It is also understood that chemical bonds are synonymous with molecular or covalent bonds. The points where carbon nanofibers connect are typically referred to as junctions or fiber junctions, and therefore may be conveniently referred to as "covalent junctions." These terms are used interchangeably throughout this specification. In the carbon network of the present invention, the junctions are formed by covalently bonded carbon atoms. Furthermore, fiber length is defined as the distance between junctions connected by the fibrous carbon material.

[0024] At least a portion of the fibers in the carbon nanofiber-containing network of the present invention are crystalline carbon nanofibers. In the present invention, preferably at least 20 wt%, more preferably at least 40 wt%, even more preferably at least 60 wt%, even more preferably at least 80 wt%, and most preferably at least 90 wt% of the carbon in the carbon network is crystalline. Alternatively, the amount of crystalline carbon is 20-90 wt%, more preferably 30-70 wt%, and even more preferably 40-50 wt%, based on the total carbon in the carbon network of the present invention. Here, "crystallinity" has its usual meaning and refers to the degree of structural regularity in a material. In other words, the carbon atoms in the nanofibers are arranged in a regular and periodic manner to some extent. Crystalline flakes or clusters can be called crystallites. Thus, carbon crystallites are individual carbon crystals. The size of a carbon crystallite is measured by the stacking height of the graphite layers. Carbon black meeting ASTM standards has a stacking height of the graphite layers within the crystallite of 11-13 Å. The carbon nanofiber-containing carbon network of the present invention has a stacking height of at least 15 Å, preferably at least 16 Å, more preferably at least 17 Å, even more preferably at least 18 Å, even more preferably at least 19 Å, and even more preferably at least 20 Å. If necessary, carbon networks having crystallites as large as 100 Å can be produced. Therefore, the carbon network of the present invention has a maximum stacking height of 100 Å or less, more preferably 80 Å or less, even more preferably 60 Å or less, even more preferably 40 Å or less, and even more preferably 30 Å or less. Therefore, it is understood that the stacking height of the graphite layers within the crystallites in the carbon network of the present invention is 15 to 90 Å, more preferably 16 to 70 Å, even more preferably 17 to 50 Å, even more preferably 18 to 30 Å, and most preferably 19 to 25 Å.

[0025] A porous, chemically interconnected carbon nanofiber-containing carbon network can be defined as having chemically interconnected carbon nanofibers, where the carbon nanofibers are interconnected through junctions, with several (usually 3 or more, preferably at least 10 or more) nanofibers covalently bonded. The carbon nanofibers are part of the network between the junctions. The fibers are typically solid (i.e., solid and solid), elongated bodies having an average diameter or thickness of preferably 1 to 500 nm, preferably 5 to 350 nm, more preferably 100 nm or less, and in one embodiment, 50 to 100 nm, compared to the average diameter of carbon black particles, which is 10 to 400 nm. In one embodiment, the average fiber length (i.e., the average distance between two junctions), as measured, for example, by SEM, is preferably 30 to 10,000 nm, more preferably 50 to 5,000 nm, more preferably 100 to 5,000 nm, and more preferably at least 200 to 5,000 nm.

[0026] The nanofibers or structures can preferably be described by an average fiber length to thickness aspect ratio of at least 2, preferably at least 3, more preferably at least 4, and most preferably at least 5, and preferably up to less than 50, in contrast to amorphous (physically associated) aggregates formed from spherical particles obtained by conventional carbon black manufacturing.

[0027] A carbon nanofiber structure may be defined as a carbon network formed by chemically interconnected carbon nanofibers. The carbon network has a three-dimensional configuration with openings between the carbon nanofibers that are accessible to a continuous phase, which may be a liquid phase, such as a solvent or aqueous phase, a gas phase, or other phase. The carbon network has diameters in all dimensions of at least 0.5 μm, preferably at least 1 μm, preferably at least 5 μm, more preferably at least 10 μm, even more preferably at least 20 μm, and most preferably 25 μm. Alternatively, the carbon network has diameters of at least 1 μm in two dimensions and at least 5 μm, preferably at least 10 μm, more preferably at least 20 μm, and most preferably 25 μm in the other dimension. Throughout this specification, the term "dimension" is used in its ordinary sense to refer to a spatial dimension. There are three spatial dimensions that are orthogonal to each other and define space in its ordinary physical sense. Furthermore, the carbon network can be at least 10 μm in diameter in two dimensions and at least 15 μm in diameter in another dimension, preferably at least 20 μm, more preferably at least 25 μm, more preferably at least 30 μm, and most preferably at least 50 μm.

[0028] The carbon nanofiber-containing carbon network may have an aggregate size of 0.1 to 100 μm, preferably 1 to 50 μm, more preferably 4 to 40 μm, most preferably 5 to 35 μm, more preferably 6 to 30 μm, more preferably 7 to 25 μm, and most preferably 8 to 20 μm, as measured by laser diffraction (ISO 13320) or dynamic light scattering analysis.

[0029] The carbon nanofiber-containing carbon network may have an intra-particle pore diameter size of 5 to 150 nm, preferably 10 to 120 nm, and most preferably 10 to 100 nm, as measured by mercury intrusion porosimetry (ASTM D4404-10).

[0030] The carbon nanofiber-containing carbon network has a size of 0.10–1.1 cm as measured by mercury intrusion porosimetry (ASTM D4404-10). 3 / g, preferably 0.51 to 1.0 cm 3 / g, most preferably 0.59 to 0.91 cm 3 / g of particle internal volume.

[0031] The surface area of ​​the carbon nanofiber-containing carbon network is preferably 40 to 120 m when measured by the Brunauer, Emmett and Teller (BET) method (ISO 9277:10). 2 / g, more preferably 45 to 110m 2 / g, and even more preferably 50-100m 2 / g, most preferably 50-90m 2 / g.

[0032] The porous, chemically interconnected carbon nanofiber-containing carbon network may also contain carbon black particles incorporated as part of the network. These particles are found at the junctions between the carbon nanofibers, although carbon black particles may also be present in other parts of the network. The carbon black particles preferably have a diameter at least 0.5 times the diameter of the carbon nanofibers, more preferably at least the same diameter as the carbon nanofibers, even more preferably at least two times the diameter of the carbon nanofibers, even more preferably at least three times the diameter of the carbon nanofibers, even more preferably at least four times the diameter of the carbon nanofibers, and most preferably at least five times the diameter of the carbon nanofibers. Preferably, the diameter of the carbon black particles is up to 10 times the diameter of the carbon nanofibers. Such mixed networks are referred to as hybrid networks.

[0033] The porous, chemically interconnected carbon nanofiber-containing carbon network has a functionalized surface. In other words, the surface contains groups that change the hydrophobicity typical of carbon to a more hydrophilic surface. The surface of the carbon network contains carboxylic acid groups, hydroxyl groups, and phenols. These groups impart some polarity to the surface and may modify the properties of the compound material in which the functionalized carbon network is embedded. Without wishing to be bound by theory, it is believed that the functional groups bond to the elastomer, for example, by forming hydrogen bonds, thus increasing the elasticity of the material. Therefore, at least the stiffness and durability of the material are modified, which may result in lower rolling resistance and increased operating life of the reinforced elastomer, particularly tires or conveyor belts containing said reinforced elastomer.

[0034] The porous, chemically interconnected carbon nanofiber-containing carbon network may contain metal catalyst nanoparticles. These are a fingerprint of the preparation method. These particles may have an average particle size of 1 nm to 100 nm. Preferably, the particles are monodisperse particles with a variation of within 10%, more preferably within 5%, of their average particle size. Non-limiting examples of nanoparticles contained in the carbon nanofiber-containing carbon network include noble metals (Pt, Pd, Au, Ag), iron group elements (Fe, Co, and Ni), Ru, and Cu. Suitable metal complexes include (i) platinum precursors, such as HPtCl; HPtCl.xH0; KPtCl; KPtCl.xH0; Pt(NH)(NO); Pt(CHO), (ii) ruthenium precursors, such as Ru(NO)(NO); Ru(dip)Cl [dip=4,7-diphenyl-1,10-phenanthroline]; RuCl, (iii) palladium precursors, such as Pd(NO), or ( iv) Nickel precursors such as NiCl or NiCl.xH0; Ni(NO); Ni(NO).xH0; Ni(CHCOO); Ni(CHCOO).xH0; Ni(AOT) [AOT = bis(2-ethylhexyl) sulfosuccinate], where x is any integer selected from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and is typically 6, 7 or 8.

[0035] Porous, chemically interconnected carbon nanofiber-containing carbon networks can be obtained by a process for producing crystalline carbon networks in a reactor 3 comprising a reaction zone 3b and a termination zone 3c by injecting a water-in-oil or bicontinuous microemulsion c, preferably containing metal catalyst nanoparticles, into reaction zone 3b at a temperature above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100°C, preferably below 3000°C, more preferably below 2500°C, and most preferably below 2000°C to produce crystalline carbon networks e, transferring these networks e to termination zone 3c, where the formation of the crystalline carbon networks is quenched or stopped by spraying with water d.

[0036] In a more preferred embodiment, the network can be obtained by the above method by burning fuel a in oxygen-containing gas b and transferring waste gas a1 from combustion zone 3a to reaction zone 3b to generate a stream of hot waste gas a1 in the combustion zone, spraying a water-in-oil or bicontinuous microemulsion c containing metal catalyst nanoparticles in reaction zone 3b containing the hot waste gas, carbonizing the emulsion at a temperature above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100°C, preferably not more than 3000°C, more preferably not more than 2500°C, and most preferably not more than 2000°C, and quenching or stopping the reaction in termination zone 3c by spraying water d to obtain a crystalline carbon network e, wherein the reactor is a furnace carbon black reactor 3 comprising, along its axis, combustion zone 3a, reaction zone 3b, and termination zone 3c.

[0037] The network is preferably obtained by the above method, the details of which are shown in the section below entitled "Method for producing a carbon network containing carbon nanofibers" and in FIG. 1A.

[0038] The term "elastomer" is a combination of elastic and polymeric. Elastomers refer to materials that have viscoelastic properties. This behavior is a combination of viscous behavior, in which the material exhibits a certain resistance to deformation when stress is applied, and elastic behavior, in which the material deforms when stress is applied and returns to its original shape when the stress is removed. Elastomers are commonly referred to as rubbers. These terms are used interchangeably and interchangeably in this specification. Elastomers can be crosslinked to improve their elastic behavior and reduce their viscous behavior. For example, rubbers such as butadiene rubber and styrene-butadiene rubber (SBR) can be vulcanized. For the purposes of this invention, the term "elastomeric matrix" is intended to mean all of the elastomers (or rubbers) of a rubber composition. Thus, the elastomeric matrix may in particular be composed of a single elastomer, as well as a blend of two or more elastomers.

[0039] Reinforced elastomers refer to elastomers containing an elastomeric matrix to which a reinforcing material, e.g., a reinforcing filler, has been added. The reinforcing material improves the properties of the elastomer, such as abrasion resistance and fatigue life in general, and in the case of tires, rolling resistance, wet traction, snow performance, abrasion resistance, and operating life. Examples of reinforcing fillers include carbon black and reinforcing inorganic fillers, such as those of the siliceous type, particularly silica (SiO2), or those of the aluminum type, particularly alumina (Al2O3). The silica used is a reinforcing silica known to those skilled in the art, particularly 450m 2 / g or less, preferably 30 to 400m 2 The silica may be any precipitated or fumed silica having a BET specific surface area and a CTAB specific surface area of ​​0.1 / g.

[0040] The carbon network of the present invention functions as a reinforcing material. The amount of porous, chemically interconnected, crystalline carbon nanofiber-containing carbon network within the reinforced elastomer is 1-60 wt%, preferably 10-55 wt%, more preferably 20-50 wt%, even more preferably 30-50 wt%, and even more preferably 35-45 wt%. Here, wt% is defined in its ordinary sense and refers to a mass percentage or mass fraction normalized to 100%. It is defined as the amount of a particular chemical (here, the carbon nanofiber-containing carbon network) divided by the sum of all chemicals (here, the elastomer, including all additive materials) multiplied by 100%. It is generally accepted that 100% refers to all materials that make up the reinforced elastomer.

[0041] Alternatively, the amount of porous, chemically interconnected crystalline carbon nanofiber structure in the reinforced elastomer may be 10 to 120 phr, preferably 15 to 60 phr, more preferably 20 to 50 phr, even more preferably 30 to 50 phr, and even more preferably 40 to 50 phr. Here, phr refers to parts per hundred of rubber, which is a rubber industry-accepted measure commonly used to describe rubber composition. Here, all components are quantified as parts by weight, where the parts by weight of the elastomer are 100, and therefore the total exceeds 100. For example, a typical rubber might contain 100 phr of rubber, 50 phr of carbon black, 30 phr of lubricant, and 20 phr of additional additives. In this case, the carbon black content is 50 phr, or 25% by weight.

[0042] If desired, the porous, chemically interconnected carbon nanofiber-containing carbon network can be mixed with other (conventional) reinforcing fillers. For example, an elastomer can be reinforced by including 10-40 phr of carbon black and 10-40 phr of the porous, chemically interconnected carbon nanofiber-containing carbon network, more preferably 20-30 phr of carbon black and 20-30 phr of the porous, chemically interconnected carbon nanofiber-containing carbon network. Other reinforcing fillers, such as an additional 5-25 phr of silica, an additional 5-25 phr of alumina, or both, may also be added.

[0043] To reinforce the elastomer, any carbon black suitable for reinforcing natural rubber may be added to the carbon nanofiber-containing carbon network. Non-limiting examples of suitable carbon black include excellent attrition furnace (SAF N110), intermediate SAF 1N220, high attrition furnace (HAF N330), easy processing channel (EPC N300), high speed extrusion furnace (FEF N550), high modulus furnace (HMF N683), semi-reinforced furnace (SRF N770), fine thermal (FT N880) and medium thermal (MT N990).

[0044] To reinforce the elastomer, any precipitated silica suitable for reinforcing natural rubber may be added to the carbon nanofiber-containing carbon network. Non-limiting examples of suitable precipitated silica include Ultrasil 7000 and Ultrasil 7005 manufactured by Evonik, Zeosil 1165MP, 1135MP, and 1115MP manufactured by Rhodia, Hi-Sil EZ150G manufactured by PPG, and Zeopol 8715, 8745, and 8755 manufactured by Huber. When silica is incorporated into the elastomer, it is usually beneficial to also include a silane coupling agent.

[0045] The reinforcing materials, e.g., networks, may be mixed into the elastomeric matrix when it is malleable or in a liquid-like state until uniformly dispersed in the elastomeric matrix. For ease of transportation and handling, these reinforcing materials may be in the form of pellets, micropearls, beads, granules, or any suitable compacted form.

[0046] If necessary, coupling agents may be used to strengthen the bond between the reinforcing filler and the elastomer. Such agents are particularly common in combination with siliceous-type fillers, but in principle may be used with any inorganic filler. Examples of such coupling fillers include mercapto-functionalized silanes and polysulfide bisalkoxysilanes.

[0047] In addition to reinforcing fillers, which are primarily added to enhance the properties of elastomers and have the benefit of reducing the cost of the final product, it may also be beneficial to add inert fillers. These inert fillers do not reinforce the elastomer and are therefore added solely to reduce the cost of the final product. The inert filler content may be 0-40% by weight, preferably 10-35% by weight, and more preferably 20-30% by weight. Alternatively, the content may be 0-80 phr, preferably 20-70 phr, and more preferably 40-60 phr. Determining and selecting the exact amount of filler is considered within the skill of those in the art. Inert fillers that may be used in the present invention may be selected from chalk, clay, bentonite, talc, kaolin, glass microbeads, glass flakes, and mixtures of these compounds. Preferably, the inert filler is chalk. The chalk may be formed of particles with an average size (by weight) of greater than 1 μm. The median diameter of the chalk particles is preferably 0.1 to 200 μm, more preferably 0.5 to 30 μm, even more preferably 1 to 20 μm. Chalk known to those skilled in the art is natural calcium carbonate (chalk) or synthetic calcium carbonate with or without a coating (e.g. with stearic acid).

[0048] The elastomer reinforced according to the present invention may be any elastomer. Preferably, the porous, chemically interconnected crystalline carbon nanofiber structure is used to reinforce butadiene rubber, most preferably styrene-butadiene rubber (SBR), ethylene propylene diene monomer rubber (EPDM), natural rubber (NR), vinylidene fluoride monomer rubber (FKM), perfluoro-elastomer (FFKM), and tetrafluoroethylene / propylene rubber (FEPM), or a combination thereof. Preferably, the elastomer is but includes but is not limited to butadiene rubber, ethylene propylene diene monomer rubber (EPDM), natural rubber (NR), vinylidene fluoride monomer rubber (FKM), perfluoro-elastomer (FFKM), and / or tetrafluoroethylene / propylene rubber (FEPM). More preferably, the elastomer comprises styrene-butadiene rubber (SBR), and even more preferably, the elastomer is styrene-butadiene rubber (SBR).

[0049] If beneficial, the reinforced elastomer may contain additional components. For example, the reinforced elastomer may contain a curing agent. In sulfur-cured or vulcanized rubbers, it may be beneficial to incorporate a sulfur donor. Alternatively, peroxides or fluorocarbons may be used. In addition, an activator may be added to accelerate the cure. For sulfur-cured or vulcanized rubbers, zinc oxide and stearic acid are typical activators. The reinforced elastomer containing the activator may also contain an accelerator to accelerate the cure, such as N-tert-butyl-2-benzothiazylsulfenamide (TBBS).

[0050] If a foam is desired in the final product, a blowing agent such as (sodium) bicarbonate may be incorporated into the elastomer. Conversely, if air pockets or bubbles are not desired, a drying agent may be added to remove any remaining traces of water.

[0051] If the final product is a bonded composite, such as a tire, hose, or belt, it is beneficial to include a binder. Suitable binders can include materials based on cobalt-based salts, such as cobalt naphthenate or cobalt stearate, and cobalt and boron complexes.

[0052] Plasticizers may be added if it is beneficial to improve the low temperature flexibility of the elastomer. If desired, the elastomer can be made flame retardant by adding flame retardants.

[0053] The use of porous, chemically interconnected carbon nanofiber-containing carbon networks to reinforce elastomers results in high-quality elastomers that are highly suitable for use in automobile tires or other automobile parts, and industrial rubber products such as conveyor belts, hoses, rubber linings, bridge bearing pads, and vibration isolation mounts. The elastomers may also be used as footwear, soles, and / or doormats.

[0054] Applicable The use of a porous, chemically interconnected carbon nanofiber-containing carbon network (in other words, a porous carbon network containing chemically interconnected carbon nanofibers) to reinforce elastomers can result in highly functional reinforced elastomers suitable for many applications. Therefore, the present invention can also be described as a reinforced elastomer containing a porous, chemically interconnected carbon nanofiber-containing carbon network, wherein the content of the porous, chemically interconnected carbon nanofiber-containing carbon network is 1 to 60 wt %, preferably 10 to 55 wt %, more preferably 20 to 50 wt %, even more preferably 30 to 50 wt %, and even more preferably 35 to 45 wt %. Alternatively, the content of the porous, chemically interconnected crystalline carbon nanofiber structure can be described as 10 to 120 phr, preferably 10 to 60 phr, more preferably 20 to 50 phr, even more preferably 30 to 50 phr, and even more preferably 40 to 50 phr. The network can be further characterized by the degree of crystallinity and intra-particle porosity, as described above.

[0055] The reinforced elastomer of the present invention is particularly suitable for use in the manufacture of tires and / or industrial rubber products. Accordingly, the present invention extends to tires and / or industrial rubber products comprising a reinforced elastomer comprising a porous, chemically interconnected carbon nanofiber-containing carbon network. Here, the tire may be an automobile tire, such as a summer or winter automobile tire, a truck tire, a bicycle or motorcycle tire, or any tire. The industrial rubber product may refer to a conveyor belt, a tube, a sealing system, etc. The reinforced elastomer of the present invention can be used in any part of a tire or industrial rubber product. It is particularly suitable for use in the tire tread, i.e., the part of the tire that comes into contact with the road surface. In a particularly preferred embodiment, the tire according to the present invention comprises a reinforced styrene-butadiene rubber. A tire comprising the reinforced elastomer of the present invention in its tread has superior properties compared to a tire having a tread containing only carbon black and / or silica.

[0056] The properties of tires according to the invention can be tailored to reduce rolling resistance without compromising wet grip or tread wear / wear resistance / operating life. If desired, the tire can be tailored to increase wet grip without compromising flexibility or stiffness. Alternatively, tires according to the invention can be tailored to obtain superior properties as snow tires without compromising wet grip. Such tires may even have improved wet grip along with improved elongation and reduced stiffness that make them suitable as snow tires. See examples. Without wishing to be bound by any theory, the improvement may be related to the network exhibiting low deformation (creep and compression).

[0057] Wet grip (WG) is usually measured according to ISO 4664-1:2011. In this accepted method, tan δ at 0° C. is used as a measure of wet grip. Preferably, the tan δ at 0° C. for the reinforced elastomers according to the invention is at least 0.1250, more preferably at least 0.1500, more preferably at least 0.1775, even more preferably at least 0.1800, even more preferably at least 0.1825, and most preferably at least 0.1850.

[0058] To assess the rolling resistance (RRC) according to ISO 4664-1:2011, tan δ at 60° C. is used as a measure. Preferably, tan δ at 60° C. for the reinforced elastomers according to the invention is at most 0.1350, more preferably at most 0.1300, even more preferably at most 0.1275, even more preferably at most 0.1250, and most preferably at most 0.1225.

[0059] The tire according to the invention is very resistant to tread wear. To evaluate this property, abrasion resistance, defined by volume loss according to ISO 4649:2010, method A, is often used. The reinforced elastomer according to the invention preferably has a tread wear resistance of 115 mm. 3 Less than 110mm, preferably 3 , and even more preferably 105 mm 3 , most preferably 100 mm 3 has a volume loss of .

[0060] Preferably, the reinforced elastomer according to the invention has a stiffness measured by the 300% modulus as defined in ISO 37:2011. The 300% modulus of the reinforced elastomer according to the invention is preferably at least 10 MPa, preferably at least 12 MPa, more preferably at least 14 MPa, even more preferably at least 16 MPa, and most preferably at least 18 MPa.

[0061] The reinforced elastomer according to the present invention preferably has an ultimate tensile strength as defined by ISO 37:2011 of at least 20 MPa, more preferably at least 22 MPa, more preferably at least 24 MPa, even more preferably at least 26 MPa, and most preferably at least 28 MPa.

[0062] Preferably, the elongation at break of the reinforced elastomer according to the present invention, as defined by ISO 37:2011, is at least 350%, more preferably at least 400%, even more preferably at least 450%, even more preferably at least 475%, and most preferably at least 500%.

[0063] The reinforced elastomer according to the present invention preferably has a tear strength as defined by ISO 34-1:2015 of at least 25 kN / m, more preferably at least 27 kN / m, even more preferably at least 29 kN / m, and most preferably at least 30 kN / m.

[0064] In one embodiment, the network is used to reduce heat buildup in reinforced elastomers.

[0065] The reinforced elastomer according to the present invention preferably has a temperature rise as defined by ISO 4666-3:2016 of at most 30° C., more preferably at most 29° C., even more preferably at most 28° C., and most preferably at most 26° C. In a preferred embodiment, the reinforced elastomer exhibiting such heat buildup properties satisfies at least one, more preferably at least two, and even more preferably all of tensile strength (ISO 37:2011), abrasion resistance (ISO 4649:2010), and rolling resistance (ISO 4664-1:2011) as described above.

[0066] The reinforced elastomer according to the present invention preferably has a creep as defined by ISO 4666-3:2016 of at most 3%, more preferably at most 2.9%, even more preferably at most 2.6%.

[0067] The challenge in developing elastomers is often to improve certain properties without compromising others. Carbon networks fulfill the need to reinforce elastomers while improving or maintaining tan δ at 0°C without compromising tan δ at 60°C and without compromising other properties, such as abrasion resistance, 300% modulus, ultimate tensile strength, elongation at break, and / or tear strength. When used in tire treads, having a high tan δ at 0°C (wet grip) and a low tan δ at 60°C (rolling resistance) is highly beneficial. Such treads make it possible to produce tires with both low rolling resistance, meaning lower fuel consumption, and high wet grip, meaning higher safety. Therefore, it is preferred that the reinforced elastomers comply with at least four, more preferably at least five, even more preferably at least six, and most preferably all, of the characteristics according to embodiment (a) in the following table:

[0068] [Table B]

[0069] These figures apply to the properties of reinforced elastomers.

[0070] It is particularly preferred that the reinforced elastomer conforms to at least four, more preferably at least five, even more preferably at least six, and most preferably all, of the characteristics according to embodiment (b) in the table above.

[0071] It is more preferred that the reinforced elastomer meets at least four, more preferably at least five, even more preferably at least six, and most preferably all of the characteristics according to embodiment (c) in the table above.

[0072] It is most preferred that the reinforced elastomer meets at least four, more preferably at least five, even more preferably at least six, and most preferably all of the characteristics according to embodiment (d) in the table above.

[0073] In one embodiment, the network is used to improve the electrical conductivity of the reinforced elastomer.

[0074] The reinforced elastomer according to the present invention is preferably a tensile strength material that is statically recognized as 10 6 Preferably, the reinforced elastomer exhibits such improved conductivity without substantially compromising hardness. The volume resistivity is preferably at least one order of magnitude lower, more preferably at least two orders of magnitude lower, than traditional carbon black. Preferably, the reinforced elastomer having advantageous volume resistivity is characterized by at least four, more preferably at least five, even more preferably at least six, and most preferably all, of the characteristics according to embodiments (a), (b), (c), or (d) in the table above.

[0075] The use of a carbon network to reinforce elastomers makes it possible to provide very tough materials with high tensile strength. This means that the material is less likely to break and therefore longer-lasting. For example, in the case of tires, this can result in long-life tires that are more resistant to bursting. The same advantage also applies to conveyor belts, which can carry heavier loads, which are more energy-efficient due to their low rolling resistance. Furthermore, the reinforced elastomers of the present invention are highly suitable for industrial rubber products. The above properties are suitable for many fields of industrial technology. For example, in the field of conveyor belts, reduced rolling resistance is very useful to reduce the power required to drive the belt. Also, wet grip can be very useful because it prevents conveyed items from falling off the belt. Furthermore, high abrasion resistance and tear strength are considered useful in the field of conveyor belts. Similarly, the reinforced elastomers of the present invention are very useful for use in (industrial) tubing. Here too, high abrasion resistance and high tear strength are considered useful.

[0076] The reinforced elastomers of the present invention can also be used in any of the other applications where rubber is typically used, including, but not limited to, footwear such as soles and boots, molded rubber parts, handle grips, plugs, caps, bumpers, diaphragms, and impact pads.

[0077] Method for producing carbon nanofiber-containing carbon network The method for obtaining a porous, chemically interconnected carbon nanofiber-containing carbon network can best be described as a modified carbon black production process, where "modified" is understood to mean that a suitable oil, preferably an oil containing at least 14 carbon atoms (greater than C14), such as a carbon black feedstock (CBFS), is provided to the reaction zone of a carbon black reactor as part of a single-phase emulsion, which is a thermodynamically stable microemulsion containing metal catalyst nanoparticles. Preferably, the emulsion is provided to the reaction zone by spraying, thus atomizing the emulsion into droplets. The process for producing modified carbon black can be carried out in a batch or semi-batch manner, but is advantageously carried out in a continuous manner. The single-phase emulsion is a microemulsion containing metal catalyst nanoparticles. A preferred single-phase emulsion comprises CBFS oil and is sometimes referred to herein as an "emulsified CBFS."

[0078] The carbon network production method can be carried out in a reactor 3 comprising a reaction zone 3b and a termination zone 3c by injecting a single-phase emulsion c, preferably a CBFS-containing emulsion, which is a microemulsion containing metal catalyst nanoparticles, into the reaction zone 3b at a temperature above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100°C, preferably below 3000°C, more preferably below 2500°C, and most preferably below 2000°C to produce porous, chemically interconnected carbon nanofiber-containing carbon networks, transferring these networks to the termination zone 3c, and quenching or stopping the formation of the porous, chemically interconnected carbon nanofiber-containing carbon networks in the termination zone by spraying with water d. The single-phase emulsion is preferably sprayed into the reaction zone. See FIG. 1A.

[0079] Alternatively, a method for producing a porous, chemically interconnected carbon nanofiber-containing carbon network is carried out in a furnace carbon black reactor 3, which includes a combustion zone 3a, a reaction zone 3b, and a termination zone 3c along the axis of the reactor 3, by burning a fuel a in an oxygen-containing gas b and transferring the waste gas a1 from the combustion zone 3a to the reaction zone 3b to generate a flow of hot waste gas a1 in the combustion zone, spraying (atomizing) a single-phase emulsion c according to the present invention, preferably a microemulsion containing metal catalyst nanoparticles, preferably a CBFS-containing emulsion, in the reaction zone 3b containing the hot waste gas, carbonizing the emulsion at an elevated temperature (above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100°C, preferably at most 3000°C, more preferably at most 2500°C, and most preferably at most 2000°C), and quenching or stopping the reaction (i.e., the formation of a porous, chemically interconnected carbon nanofiber-containing carbon network) in the termination zone 3c by spraying water d. Reaction zone 3b comprises at least one inlet (preferably a nozzle) for introducing the emulsion, preferably by atomization, see Figure 1A.

[0080] The residence time of the emulsion in the reaction zone of the furnace carbon black reactor may be relatively short, preferably 1 to 1000 milliseconds, more preferably 10 to 100 milliseconds. Longer residence times may affect the properties of the carbon network. For example, longer residence times may result in larger crystallite size.

[0081] According to conventional carbon black manufacturing methods, the oil phase may be aromatic and / or aliphatic and preferably contains at least 50% by weight (based on the total weight of the oil), more preferably at least 70% by weight of C14 or higher. Typical oils that can be used to obtain a stable emulsion include, but are not limited to, carbon black feedstock (CBFS), phenolic oil, anthracene oil, (short-medium-long chain) fatty acids, fatty acid esters, and paraffins. The oil is preferably C14 or higher. In one embodiment, the oil preferably has high aromaticity. In the art, aromaticity is preferably characterized by the Bureau of Mines Correlation Index (BMCI). Preferably, the oil has a BMCI greater than 50. In one embodiment, the oil has low aromaticity, preferably a BMCI less than 15.

[0082] CBFS is an economically attractive oil source for the present invention, preferably a heavy hydrocarbon mixture containing primarily C14-C50, with the total C14-C50 preferably comprising at least 50 wt. % of the feedstock, more preferably at least 70 wt. %. The most important feedstocks used to produce carbon black include clarified slurry oil (CSO) obtained from fluid catalytic cracking of diesel fuel, ethylene cracking residue from naphtha steam cracking, and coal tar oil. The presence of paraffins (less than C15) substantially reduces their suitability, and higher aromaticity is preferred. The concentration of aromatic compounds is determined by the rate at which carbon nuclei are formed. Carbon black feedstocks preferably have a high BMCI, which can result in high yields with minimal heat input and therefore reduce production costs. In a preferred embodiment and in accordance with current CBFS specifications, oils containing a mixture of oils have a BMCI value greater than 120. Those skilled in the art will have no difficulty in determining which CBFS are suitable, but it should be noted, merely as a guideline, that from a yield standpoint, the CBFS preferably has a BMCI value of 120, and even more preferably greater than 132. The amount of asphaltenes in the oil is preferably less than 10 wt.%, preferably less than 5.0 wt.%, of the CBFS weight. A low sulfur content in the CBFS is preferred, as sulfur has a detrimental effect on product quality, leads to low yields, and is corrosive to equipment.

[0083] It is preferred that the sulfur content of the oil be less than 8.0 wt.%, preferably less than 4.0 wt.%, more preferably less than 2.0 wt.%, according to ASTM D1619.

[0084] The emulsion, preferably a CBFS-containing emulsion, is a "single-phase emulsion," which is understood to mean that the oil and water phases optically appear as a miscible mixture with no visible physical separation of the oil, water, or surfactant. Single-phase emulsions can be macroemulsions or microemulsions and can be either kinetically or thermodynamically stable. The complete breakdown (coalescence) of an emulsion, i.e., the separation of the system into bulk oil and water phases, is generally believed to be controlled by four different droplet loss mechanisms: Brownian flocculation, creaming, flocculation-sedimentation, and heterogenization.

[0085] In the present invention, a "stable single-phase emulsion" is understood to mean that the emulsion does not exhibit visible physical separation, reflecting that the emulsion preferably does not exhibit a change in pH of more than 1.0 and / or a change in viscosity of more than 20% over a period exceeding the carbon network production time. The term "stable" can also mean "thermodynamically stable" or "kinetically stable" (by the addition of energy, i.e., by mixing). In practice, a single-phase emulsion is considered stable if demixing does not occur optically, i.e., the emulsion remains single-phase for at least 1 minute after preparation. Thus, it is preferred that the emulsion maintain its pH within 1.0 and / or its viscosity within 20% for at least 1 minute, preferably at least 5 minutes, after preparation. While long-term stability is preferred for handling purposes, manufacturing processes can still benefit from using emulsions that are stable for a relatively short period of time, such as 1 minute, preferably 5 minutes. Emulsion stability may be extended by adding energy (mixing), and short-term stability may be extended by in-line mixing. Although macroemulsions are not thermodynamically stable and will always revert to the original immiscible separate oil and water phases, the rate of breakup may be slow enough to make them kinetically stable during manufacturing.

[0086] The amounts of water and oil are not considered to be critical as long as a stable single-phase emulsion is obtained, but it should be noted that reducing the amount of water (and increasing the amount of oil) improves yield. The water content is typically 5 to 50% by weight of the emulsion, preferably 10 to 40% by weight, even more preferably 30% by weight or less, and more preferably 10 to 20% by weight of the emulsion. Larger amounts of water are conceivable, but at the expense of yield. Without wishing to be bound by theory, the inventors believe that the aqueous phase contributes to the shape and morphology of the resulting network.

[0087] The choice of surfactant is not critical as long as the combination of oil, water, and surfactant results in a stable microemulsion as described above. As further guidance to those skilled in the art, surfactants can be selected based on the hydrophobicity or hydrophilicity of the system, i.e., the hydrophilic-lipophilic balance (HLB). The HLB of a surfactant is a measure of hydrophilicity or lipophilicity and is determined by calculating the values ​​of various regions of the molecule according to the Griffin or Davies method. The appropriate HLB value depends on the type of oil and the amount of oil and water in the emulsion, and can be easily determined by those skilled in the art based on the requirement to maintain a thermodynamically stable single-phase emulsion as described above. Emulsions containing more than 50% by weight of oil and preferably less than 30% by weight of an aqueous phase are believed to be best stabilized by surfactants with an HLB value of more than 7, preferably more than 8, more preferably more than 9, and most preferably more than 10. On the other hand, emulsions containing up to 50% by weight of oil are believed to be best stabilized by surfactants with an HLB value of less than 12, preferably less than 11, more preferably less than 10, most preferably less than 9, and especially less than 8. The surfactant is preferably selected to be compatible with the oil phase. For emulsions containing CBFS, surfactants with high aromaticity are preferred, while low BMCI oils, such as those characterized by a BMCI of less than 15, are believed to be best stabilized using aliphatic surfactants. The surfactant may be cationic, anionic, or nonionic, or a mixture thereof. One or more nonionic surfactants are preferred to increase yield, since no ions remain in the final product. To obtain a clean tail gas stream, the surfactant is preferably low in sulfur and nitrogen, and preferably sulfur and nitrogen-free. Non-limiting examples of typical nonionic surfactants that can be used to obtain stable emulsions include commercially available surfactants such as Tween, Span, Hypermer, Pluronic, Emulan, Neodol, Triton X, and Tergitol.

[0088] In the present invention, a microemulsion is a dispersion composed of water, oil (preferably CBFS), and surfactant, which is a single optically and thermodynamically stable liquid with dispersed domain diameters ranging from approximately 1 to 500 nm, preferably 1 to 100 nm, and typically 10 to 50 nm. In a microemulsion, the dispersed phase domains are either spherical (i.e., droplets) or interconnected (leading to a bicontinuous microemulsion). In preferred embodiments, surfactant tails form a continuous network in the oil phase of a water-in-oil (w / o) emulsion or a bicontinuous emulsion. The water domains should contain a metal catalyst, preferably with an average particle size of 1 nm to 100 nm.

[0089] The single-phase emulsion, i.e., water-in-oil or bicontinuous microemulsion, preferably bicontinuous microemulsion, further comprises metal catalyst nanoparticles, preferably having an average particle size of 1 to 100 nm. Those skilled in the art will find various guidance for producing and using such nanoparticles in the field of carbon nanotubes (CNTs). These metal nanoparticles have been found to improve network formation and reproducibility, both in terms of speed and yield. Methods for producing suitable metal nanoparticles are described in Vinciguerra et al. "Growth mechanisms in chemical vapor deposited carbon nanotubes" Nanotechnology (2003) 14, 655; Perez-Cabero et al. "Growing mechanism of CNTs: a kinetic approach" J. Catal. (2004) 224, 197-205; Gavillet et al. "Microscopic mechanisms for the catalyst assisted growth of single-wall carbon nanotubes" Carbon. (2002) 40, 1649-1663; and Amelinckx et al. "A formation mechanism for catalytically grown helix-shaped graphite nanotubes" Science (1994) 265, 635-639, the contents of which with respect to the production of metal nanoparticles are incorporated herein by reference.

[0090] Metal catalyst nanoparticles are used in bicontinuous or water-in-oil microemulsions, preferably CBFS-containing bicontinuous or water-in-oil microemulsions. In one embodiment, bicontinuous microemulsions are most preferred. Advantageously, the uniformity of the metal particles is controlled in the (bicontinuous) microemulsion by mixing a first (bicontinuous) microemulsion, whose aqueous phase contains a metal complex salt capable of being reduced to metal particles, with a second (bicontinuous) microemulsion, whose aqueous phase contains a reducing group capable of reducing the metal complex salt. Upon mixing, the metal complex is reduced to form metal particles. The controlled (bicontinuous) emulsion environment stabilizes the particles against calcination or Ostwald ripening. The size, concentration, and durability of the catalyst particles are easily controlled. It is considered routine experimentation to adjust the average metal particle size within the above range, for example, by varying the molar ratio of metal precursor to reducing agent. Increasing the relative amount of reducing agent results in smaller particles. The metal particles thus obtained are monodisperse, with a deviation from the average particle size preferably within 10%, more preferably within 5%. Furthermore, current technology does not limit the metal precursors as long as they are reduced. Non-limiting examples of nanoparticles contained in the carbon nanofiber-containing carbon network include noble metals (Pt, Pd, Au, Ag), iron group elements (Fe, Co, and Ni), Ru, and Cu. Suitable metal complexes include (i) platinum precursors, e.g., HPtCl; HPtCl.xH0; KPtCl; KPtCl.xH0; Pt(NH)(NO); Pt(CHO), (ii) ruthenium precursors, e.g., Ru(NO)(NO); Ru(dip)Cl [dip = 4,7-diphenyl-1,10-phenanthroline]; RuCl; (iii) palladium precursors, e.g., Pd(NO); may be (iv) a nickel precursor, e.g., NiCl or NiCl.xH0; Ni(NO); Ni(NO.) xH0; Ni(CHCOO); Ni(CHCOO).xH0; Ni(AOT) [AOT = bis(2-ethylhexyl) sulfosuccinate], where x may be any integer selected from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and is typically 6, 7 or 8.Non-limiting examples of suitable reducing agents include hydrogen gas, sodium borohydride, sodium hydrogen sulfate, hydrazine or hydrazine hydrate, ethylene glycol, methanol, and ethanol. Citric acid and dodecylamine can also be used. The type of metal precursor is not essential to the present invention. The metal of the particles in the (bicontinuous) microemulsion is preferably selected from the group consisting of Pt, Pd, Au, Ag, Fe, Co, Ni, Ru, and Cu, and mixtures thereof, to control the morphology of the carbon structure network that ultimately forms. The metal nanoparticles ultimately become embedded within these structures, and the metal particles are physically attached to the structure. There is no minimum concentration of metal particles to form these networks; in fact, networks are formed using the modified carbon black production method of the present invention, and it has been found that the yield increases with metal particle concentration. In a preferred embodiment, the concentration of the active metal is at least 1 mM, preferably at least 5 mM, preferably at least 10 mM, more preferably at least 15 mM, more preferably at least 20 mM, in particular at least 25 mM, most preferably at most 3500 mM, preferably at most 3000 mM. In one embodiment, the concentration of the metal nanoparticles is at most 250 mM. These are catalyst concentrations relative to the volume of the aqueous phase of the (bicontinuous) microemulsion.

[0091] Atomization of the single-phase emulsion, preferably a CBFS-containing emulsion, is preferably achieved by spraying using a nozzle 4, which allows the emulsion droplets to come into contact with the hot waste gas a1 in the reaction zone 3b, whereby traditional carbonization, network formation and subsequent condensation occur, producing the carbon network of the present invention. The impregnation step is preferably carried out at temperatures above 600°C, preferably between 700 and 3000°C, more preferably between 900 and 2500°C, more preferably between 1100 and 2000°C.

[0092] In one aspect, the porous, chemically interconnected carbon nanofiber-containing carbon network preferably has the following characteristics:

[0093] (i) an iodine adsorption capacity (IAN) according to ASTM D1510 of at least 30 mg / g, preferably at least 50 mg / g, more preferably at least 100 mg / g, and most preferably at least 150 mg / g. Alternatively, the IAN according to ASTM D1510 is between 30 and 1000 mg / g, preferably between 100 and 800 mg / g, and more preferably between 30 and 500 mg / g; (ii) At least 30 m in accordance with ASTM D6556 2 / g, preferably at least 50m 2 / g, more preferably at least 100m 2 / g, most preferably at least 150m 2 / g nitrogen surface area (N2SA). Alternatively, N2SA is defined as 30 to 1000 m2 according to ASTM D6556. 2 / g, preferably 100 to 800m 2 / g, more preferably 30 to 500m 2 / g; (iii) At least 40 m in accordance with ASTM D6556 2 / g, more preferably at least 70m 2 / g, and even more preferably at least 100m 2 / g, and even more preferably at least 125m 2 / g, most preferably at least 150m 2 / g. Alternatively, STSA is the statistical thickness surface area (STSA) of 40 to 1000 m according to ASTM D6556. 2 / g, preferably 100 to 800m 2 / g, more preferably 120 to 500m 2 / g; (iv) An Oil Average Number (OAN) according to ASTM D2414 of at least 50 cc / 100 g, preferably at least 75 cc / 100 g, more preferably at least 100 cc / 100 g, even more preferably at least 125 cc / 100 g, and most preferably at least 150 cc / 100 g. Alternatively, the OAN according to ASTM D2414 is between 50 and 500 cc / 100 g, preferably between 150 and 350 cc / 100 g.

[0094] where: IAN = Iodine Adsorption Number: the number of grams of iodine adsorbed per kilogram of carbon black under specified conditions as defined in ASTM D1510; N2SA = Nitrogen surface area: total surface area of ​​carbon black calculated from nitrogen adsorption data using BET theory according to ASTM D6556; STSA = Statistical Thickness Surface Area: the external surface area of ​​carbon black calculated from nitrogen adsorption data using Boer theory and the carbon black model according to ASTM D6556; and OAN = Oil Supply Number: The number of square centimeters of dibutyl phthalate (DBP) or paraffin oil adsorbed by 100 g of carbon black under specified conditions. The OAN value is proportional to the degree of agglomeration of the carbon black structure, as determined in accordance with ASTM D2414. The compound has at least one, preferably at least two, more preferably at least three, and most preferably all of the above.

[0095] The porous, chemically interconnected carbon nanofiber-containing carbon network exhibits superior properties compared to traditional carbon black with respect to each of IAN, NSA (or NSA), STSA, and OAN, all of which are typical parameters for characterizing carbon black materials. The porous, chemically interconnected carbon nanofiber-containing carbon network is preferably characterized by at least one, preferably at least two, and more preferably all of (i), (ii), and (iii), as these are common ways of characterizing the surface area properties of a material. In one embodiment, the porous, chemically interconnected carbon nanofiber-containing carbon network exhibits at least one of (i), (ii), and (iii), and further complies with (iv).

[0096] Example: Properties of carbon network in SBR The performance of styrene-butadiene rubber reinforced with a carbon network according to the present invention ("Carbon Network") was compared with that of rubber reinforced with a known carbon black (N115) obtained from Cabot Corporation. The carbon network was prepared similarly to the method of Example 1 of International Publication No. 2018 / 002137, the contents of which are incorporated herein by reference, and used as is. The average intraparticle pore size of the network was 20 nm, as measured by mercury intrusion porosimetry (ASTM D4404-10). Such SBR compounds are commercially used as reinforcing components in both tire frameworks and industrial rubbers. Performance was evaluated according to ASTM D3191, which describes the compounding, processing, and test methods for the evaluation and production control of carbon black. The standards used to measure the properties of the elastomeric compounds are listed in Table 1.

[0097] The compound was prepared by mixing 100 phr of Europrene 1502, 50 phr of carbon network or carbon black, 3 phr of zinc oxide, 1 phr of stearic acid, 1.75 phr of sulfur, and 1 phr of TBBS. The main components were mixed in stages as follows: t = 0 min: Add all of the Europrene; t = 1 min: Add 50% of the carbon network or carbon black, zinc oxide, and stearic acid; t = 2 min: Add the remaining carbon network or carbon black; t = 4 min: Sweep; and t = 5 min: Dump. The rotor speed was constant at 75 rpm. The starting temperature was 50°C, and the dump temperature was approximately 160°C. The dosage rate in the mixer (Banbury type, 1.6 liters, Farrel Bridge) was 70%. The vulcanizing agents (sulfur and TBBS) were added to the compound at 50°C and mixed using a two-roll mill (1 liter, Agila). The samples were vulcanized in an electrically heated Fontijne Holland Presse at 160°C and conditioned at 23°C for 24 hours before testing.

[0098] The reinforced elastomers were tested according to the specifications shown in Table 1. The test results are shown in Table 2. From Table 2, it can be seen that the carbon networks according to the invention combine a high tan δ at 0°C and a low tan δ at 60°C, which means that they have improved rolling resistance (RRC) combined with wet grip (WG), without compromising other important vectors, such as abrasion resistance (measured by volume loss), tensile strength, and elongation. Thus, the carbon networks of the invention allow for the production of products, such as tires or conveyor belts, with low rolling resistance, which provides benefits in energy consumption without compromising other properties. The carbon networks of the invention allow for the production of tires or conveyor belts that are more durable, stronger, and less likely to break when stretched.

[0099] [Table 1]

[0100] [Table 2]

[0101] It was also found that the same carbon network reduced volume resistivity by three orders of magnitude compared to N115 at the same hardness level.

[0102] [Table 3]

[0103] Example: Properties of carbon networks in natural rubber (NR) The performance of natural rubber reinforced with a carbon network according to the present invention ("carbon network") was compared with that of rubber reinforced with known carbon blacks (N115, N550) obtained from Cabot Corporation. The carbon network was prepared similarly to the method of Example 1 of International Publication No. 2018 / 002137, the contents of which are incorporated herein by reference, and used as is. The average intraparticle pore size of the network was 20 nm, as measured by mercury intrusion porosimetry (ASTM D4404-10). Such NR compounds are commercially used as reinforcing components in both tire treads and industrial rubbers. Performance was evaluated according to ASTM D3191, which describes the compounding, processing, and test methods for the evaluation and production control of carbon black. The standards used to measure the properties of the elastomeric compounds are listed in Table 1.

[0104] The compound was prepared by mixing 100 phr of TSR-10, 50 phr of carbon network or carbon black, 5 phr of zinc oxide, 3 phr of stearic acid, 2.5 phr of sulfur, and 0.6 phr of MBTS. The main components were mixed in stages as follows: t = 0 min: Add all NR; t = 1 min: Add 50% of the carbon network or carbon black, zinc oxide, and stearic acid; t = 2 min: Add the remaining carbon network or carbon black; t = 4 min: Sweep; and t = 5 min: Dump. The rotor speed was constant at 75 rpm. The starting temperature was 50°C, and the dump temperature was approximately 160°C. The dosage rate in the mixer (Banbury type, 1.6 liter, Farrel Bridge) was 70%. The vulcanizing agents (sulfur and MBTS) were added to the compound at 50°C and mixed using a two-roll mill (1 liter, Agila). The samples were vulcanized in an electrically heated Fontijne Holland Presse at 160°C and conditioned at 23°C for 24 hours before testing.

[0105] The reinforced elastomers were tested according to the specifications shown in Table 4.

[0106] The test results are shown in Table 5. Table 5 shows that the carbon network according to the present invention combines a lower tan δ at 60°C with improved tensile strength, elongation, and tear strength. Thus, the carbon network according to the present invention allows for the production of products, such as tires or conveyor belts, with low rolling resistance, which provides benefits in energy consumption without compromising other properties. The carbon network according to the present invention allows for the production of tires or conveyor belts that are more durable, stronger, and less likely to break when stretched. Furthermore, the performance was compared with that of N550 (carbon black, Carbot Corporation), which is commonly used, for example, in hoses. The results in Table 6 suggest improved flexibility and abrasion resistance.

[0107] [Table 4]

[0108] [Table 5]

[0109] [Table 6]

Claims

1. 1. Use of a porous carbon network comprising covalently interconnected carbon nanofibers for reinforcing an elastomer, wherein the carbon network is an intraparticle porous network, the carbon nanofibers are chemically interconnected with other nanofibers in the network through junctions, the pores in the network have an intraparticle pore size of 5 to 150 nm as measured by mercury intrusion porosimetry according to ASTM D4404-10, at least 20 wt. % of the carbon in the carbon network is crystalline, and the carbon nanofibers have an average fiber length-to-thickness aspect ratio of at least 2.

2. 2. The use according to claim 1, wherein the content of the carbon network in the reinforced elastomer is 1 to 60% by weight or 10 to 120 phr.

3. The use according to claim 1 or 2, wherein the carbon nanofibers have an average fiber length of 30 to 10,000 nm.

4. The use according to any one of claims 1 to 3, wherein the reinforced elastomer is used in tires or industrial rubber products.

5. The use according to any one of claims 1 to 4 for reducing heat buildup in the reinforced elastomer.

6. Use according to any one of claims 1 to 5 for improving the electrical conductivity of the reinforced elastomer.

7. Use according to any one of claims 1 to 6, wherein the reinforced elastomer meets at least four of the characteristics according to (a) in the table below. Table 1

8. Use according to any one of claims 1 to 7, wherein the reinforced elastomer meets at least four of the characteristics according to (b) in the table below. Table 2

9. The use described in any one of claims 1 to 8, wherein the reinforced elastomer meets at least four of the characteristics according to (c) in the table below. Table 3

10. The use described in any one of claims 1 to 9, wherein the reinforced elastomer meets at least four of the characteristics according to (d) in the table below. Table 4

11. The use according to any one of claims 1 to 10, wherein the carbon network is obtainable by a method using a reactor 3 comprising a reaction zone 3b and a termination zone 3c, injecting a water-in-oil or bicontinuous microemulsion c comprising metal catalyst nanoparticles into the reaction zone 3b at a temperature above 600°C to obtain a crystalline carbon network e, transferring the network e to the termination zone 3c, and spraying water d into the termination zone to quench or stop the formation of the crystalline carbon network.

12. A reinforced elastomer comprising 10 to 60 wt % or 10 to 120 phr of a porous carbon network comprising covalently interconnected carbon nanofibers, wherein the carbon network is an intraparticle porous network, the carbon nanofibers are chemically interconnected to other nanofibers in the network via junctions, the pores in the network have an intraparticle pore size of 5 to 150 nm as measured by mercury intrusion porosimetry according to ASTM D4404-10, at least 20 wt % of the carbon in the carbon network is crystalline, and the carbon nanofibers have an average length-to-thickness aspect ratio of at least 2.

13. 13. The reinforced elastomer of claim 12, wherein the reinforced elastomer meets at least four of the characteristics according to (a) in the table below. Table 5

14. 14. The reinforced elastomer of claim 12 or 13, wherein the reinforced elastomer meets at least four of the characteristics according to (b) in the table below. Table 6

15. A reinforced elastomer described in any one of claims 12 to 14, wherein the reinforced elastomer meets at least four of the characteristics according to (c) in the table below. Table 7

16. A reinforced elastomer described in any one of claims 12 to 15, wherein the reinforced elastomer meets at least four of the characteristics according to (d) in the table below. Table 8

17. 17. The reinforced elastomer according to any one of claims 12 to 16, wherein the carbon network is obtainable by a method using a reactor 3 comprising a reaction zone 3b and a termination zone 3c, injecting a water-in-oil or bicontinuous microemulsion c comprising metal catalyst nanoparticles into the reaction zone 3b at a temperature above 600°C to obtain a crystalline carbon network e, transferring the network e to the termination zone 3c, and spraying water d into the termination zone to quench or stop the formation of the crystalline carbon network.

18. An article comprising the reinforced elastomer of any one of claims 12 to 17.

19. 19. The article of claim 18, which is a tire or industrial rubber product.

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