RU2806214C2 - Application of carbon nets containing carbon nanofibers - Google Patents

Abstract

FIELD: reinforcing elastomers.

SUBSTANCE: use of a porous carbon net that contains chemically interconnected carbon nanofibers for the reinforcement of elastomers is disclosed, in which the carbon net has intraparticle porosity, and in which the carbon nanofibers are interconnected with other carbon nanofibers in the net by chemical bonds at their intersections, and the pores in the net have a diameter of intraparticle pores of 5-150 nm as determined by mercury porosimetry, with at least 20 wt.% of the carbon in the carbon nets being in crystalline form, and the carbon nanofibers having an average length to fiber thickness ratio of at least 2. A reinforced elastomer containing the specified porous carbon mesh, and a finished product, which is a tire or rubber product containing the specified reinforced elastomer, are also disclosed.

EFFECT: group of inventions provides reinforcement of elastomers with improvement of their properties.

11 cl, 2 dwg, 8 tbl, 2 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The present invention relates to the field of reinforcing elastomers, in particular to the reinforcement of tires or rubber products.

PREVIOUS ART

Elastomers are widely used in many technological applications such as tires, sealing systems, conveyor systems such as belts, hoses, automotive weather protection, molded rubber products, etc. The elastomers market can be segmented into tires and rubber products, where the key rubber component for general purpose compounds may be nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), ethylene propylene diene monomer rubber (EPDM) and/or natural rubber, and for high performance (high quality) compounds these may be vinylidene fluoride monomer (FKM) rubbers, perfluoroelastomers (FFKM), tetrafluoroethylene/propylene rubbers (FEPM) and/or hydrogenated nitrile butadiene rubber (HNBR).

Elastomer end products, such as tires, often contain various rubbers mixed with additional chemical and structural components to give the final product the desired properties. For example, a typical automobile tire may contain approximately 45% by weight elastomers (such as natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR) and butyl rubber), approximately 20% reinforcing agent (such as carbon black and/or silica) , approximately 15% metal, approximately 5% textile, and various additives such as zinc oxide, sulfur, etc. Tires, such as automobile tires, may contain carbon black in an amount of 30-90 parts by weight. per 100 parts by mass polymer or more. Patent document EP 2880090 describes that certain ratios of natural rubber, nanocarbon and carbon black reinforcing agents are favorable for improving the properties of tires.

Also, rubber products (conveyor belts, fuel hoses) usually contain large amounts of reinforcing agents such as carbon black and/or silica. An additional requirement here may be to prevent the buildup of electrostatic charge that can occur when two non-conductive materials move relative to each other. Any discharge of said stored electrostatic charge may result in various problems or hazards, including electronic equipment failure or fire. These risks can be prevented by incorporating carbon black and thereby making at least one of the materials (semi)conductive. Also, sealing systems typically contain soot. In this case, there is an additional requirement for surface smoothness. In order to obtain the best possible seal, any surface defects must be avoided or at least minimized.

In modern technology, carbon black is the predominant reinforcing agent because it is cheap and also improves the processing of the elastomer. A large amount of research has been devoted to tuning (the production method) of carbon black to obtain optimal results in the final product. This has resulted in a variety of carbon black grades that vary in average particle size, specific surface area, porosity, impurity levels, etc. There is still a need to further improve the performance of elastomers and to find technology that can produce improved elastomers using mass production at an affordable cost.

In the quest to optimize the properties of the final elastomer product, it has been discovered that some technologically advanced products, such as carbon nanotubes, can improve the properties of elastomers when they are included as an additive. For example, patent document WO 2016/045960 describes the use of nanoscale carbon structures (nanocarbon, such as carbon nanotubes) in the preparation of reinforced styrene butadiene rubber (SBR). However, these materials are difficult to produce on a large scale. Often these materials are difficult to disperse or are incompatible with some of the other ingredients. Their use in industrial settings requires special equipment, further reducing productivity.

Patent document US2017/369660 describes carbon nanotube-elastomer composites, a method for preparing such composites, and their use as a sealing material. Also mentioned is a network of tubes that are physically connected through percolation.

There is a need to further develop the properties of elastomers that can be mass-produced in a cost-effective manner and produce higher quality and more efficient end products. There is a need to produce automobile tires with lower rolling resistance to reduce fuel consumption and solve environmental problems while maintaining other important tire properties. There is also a need to improve tire grip on wet roads or snow while maintaining consistent rolling resistance and service life.

Likewise, there is a need to produce improved elastomers to produce conveyor belts with lower rolling resistance to reduce operational power consumption, as well as belts with high damage resistance to prevent downtime due to cuts, abrasions, wear and punctures. There is also a need in the field of sealing systems for more advanced sealing systems that provide improved sealing properties as well as improved compression properties (ie, service life) of the rubber compound.

SUMMARY OF THE INVENTION

The present inventors have discovered that a newly developed grade of carbon nanofiber-containing carbon meshes can be advantageously used to improve the properties of elastomers to the extent that the above-mentioned needs in the art can be met. More specifically, it has been found that porous, chemically interconnected, carbon nanofiber-containing carbon networks can be used to reinforce elastomers. This is described in more detail in the experimental sections of this document. It has been found that these porous, chemically interconnected, carbon nanofiber-containing carbon networks having high intraparticle porosity can be used to produce a highly reinforced elastomer. Without being bound by any particular theory, it is believed that this is due to the intraparticle porosity of these networks. The strength of elastomers can be improved without the usual disadvantages such as reduced tan delta at 0°C (wet grip), and/or increased tan delta at 60°C (rolling resistance), and/or increased temperature due to accumulation heat, which leads to deformation (creep). The reinforced elastomer composite of the present invention is very useful in many technological applications such as tires or rubber products such as seals, gaskets, conveyor belts, tubes and the like. It allows tires, such as automobile tires or conveyor belts, to be produced that have lower rolling resistance without reducing the tire's wet grip or service life.

Carbon meshes may contain crystalline carbon nanofibers. Carbon nanofibers can have a length of 30-10,000 nm. In addition, carbon networks have intraparticle porosity. The carbon networks of the present invention can advantageously be added to elastomers at an inclusion level of 1-60 wt% or alternatively 10-120 phr. at 100 m.h. resin.

The present invention further extends to a method for producing said carbon meshes, largely using a conventional set employing a reductive (pyrolysis) or oxidative (partial or complete combustion) carbon black production process.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1A is a schematic diagram of a continuous furnace soot production process in accordance with the present invention, which comprises, along the axis of the reactor 3, a combustion zone 3a, a reaction zone 3b and a termination zone 3c, by generating a hot exhaust gas stream a1 in the combustion zone by combustion fuel in oxygen-containing gas b and passing exhaust gas a1 from combustion zone 3a into reaction zone 3b, spraying a single-phase emulsion c into reaction zone 3b containing the hot exhaust gas, carbonizing said emulsion at an elevated temperature, and quenching or stopping the reaction in zone 3c by completing spraying water d to obtain crystalline carbon networks e in accordance with the present invention;

Fig. 1B is a schematic diagram of a process for semi-batch production of carbon black by spraying a single-phase emulsion c through a nozzle 4 at the top of a reactor 3 into a reaction zone 3b at an elevated temperature, carbonizing said emulsion at an elevated temperature in a reaction zone 3b, and collecting crystalline carbon networks e at the bottom of the reactor . In addition, two gas inlets are present which enter the reactor from the top for adding an inert gas f, preferably nitrogen, to control and/or reduce the oxygen level, and for introducing a carbonaceous gas g, preferably acetylene or ethylene, into the reactor.

OPTIONS FOR IMPLEMENTING THE PRESENT INVENTION

1. The use of a porous, chemically interconnected carbon mesh containing carbon nanofibers for reinforcing elastomers;

2. Use according to embodiment 1, wherein the level of incorporation of the carbon network into the reinforced elastomer is 1-60 wt.% or 10-120 p.m. at 100 m.h. resins;

3. Use according to embodiment 1 or 2, wherein the carbon mesh contains crystalline carbon nanofibers;

4. Use according to any of the preceding embodiments, wherein the carbon mesh is an intraparticle porous mesh;

5. Use according to any of the preceding embodiments, wherein the average length of the carbon nanofibers is 30-10000 nm;

6. Use according to any of the preceding embodiments, wherein the reinforced elastomer is used in tires or rubber products;

7. Reinforced elastomer containing 10-60 wt.% or 10-120 ppm. at 100 m.h. porous, chemically interconnected resin containing carbon nanofibers of a carbon mesh;

8. Use in accordance with any of embodiments 1-6 or the reinforced elastomer in accordance with embodiment 7, wherein the reinforced elastomer is at least 4, more preferably at least 5, even more preferably at least 6, and most preferably all of the following characteristics in accordance with embodiment (a) in the table:

Preferred (a) More preferable (b) Even more preferably (c) Most preferred (d) ISO4664-1:2011, tan delta at 0 (°C) ≥ 0.1250 ≥ 0.1500 ≥ 0.1775 ≥ 0.1800 ISO4664-1:2011, tan delta at 60 (°C) ≤ 0.1350 ≤ 0.1300 ≤ 0.1300 ≤ 0.1275 ISO 4649:2010, volume loss (mm ³ ) < 115 < 115 < 110 < 110 ISO37:2011, maximum tensile strength (MPa) ≥ 22 ≥ 24 ≥ 26 ≥ 28 ISO37:2011 elongation at break (%) ≥ 350 ≥ 400 ≥ 450 ≥ 475 ISO 4666-3:2016, Temperature rise (heat storage) (°C) ≤30 ≤ 29 ≤ 28 ≤ 26 ISO 4666-3:2016, creep (%) ≤ 3 ≤ 2.9 ≤ 2.8 ≤ 2.6

9. Use in accordance with any of embodiments 1-6 and 8, or a reinforced elastomer in accordance with any of embodiments 7-8, wherein the carbon mesh is produced by a process for producing crystalline carbon meshes in a reactor 3 that contains reaction zone 3b and completion zone 3c by injecting a water-in-oil microemulsion or intercontinuous microemulsion c 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 up to 3000°C, more preferably up to 2500°C, most preferably up to 2000°C, for the production of crystalline carbon e meshes, transmission these grids e to the completion zone 3c, and quenching or stopping the formation reaction of the crystalline carbon grids in the termination zone by spraying water d;

10. A finished product comprising a reinforced elastomer in accordance with any of embodiments 7-9; And

11. The finished product in accordance with embodiment 10, which is a tire or rubber product.

DETAILED DESCRIPTION

In a first aspect, the present invention can be described as the use of porous, chemically interconnected, carbon nanofiber-containing carbon networks (ie, porous carbon networks that contain chemically interconnected carbon nanofibers) for reinforcing elastomers. One skilled in the art will understand that a porous mesh refers to a three-dimensional structure that allows fluids or gases to pass through it.

Porous mesh can also be referred to as porous media or porous material. The pore space volume of the porous carbon networks in accordance with the present invention is 0.1-1.5 cm ³ /g, preferably 0.2-1.5 cm ³ /g, more preferably 0.3-1.3 cm ³ /g and most preferably 0.4-1.3 cm ³ /g when measured using the Brunauer, Emmett and Teller (BET) method (ASTM D6556-09).

The porous carbon network of the present invention (or the porous carbon network particle of the present invention) can be considered as a large molecule in which the carbon atoms are substantially covalently bonded. This means that a porous carbon network particle is a particle with chemically interconnected (i.e., covalently bonded) fibers having intraparticle porosity, as opposed to interparticle porosity, which refers to a porous network created by a plurality of molecules or particles in which the pores formed by the space between physically aggregated particles or molecules. In the context of the present invention, intraparticle porosity may also be referred to as intramolecular porosity, since a carbon network particle according to the present invention may be considered as a large molecule having pores. Therefore, intraparticle porosity and intramolecular porosity have the same meaning in this text and can be used interchangeably to describe the porous networks of the present invention. Compare with traditional carbon black, which does not have an intraparticle porous structure within the soot particle, but aggregates of soot particles may have interparticle porosity properties. While interparticle/intermolecular pores represent the space between physical aggregated particles (networks), intraparticle/intramolecular pores represent the space within the network itself.

Without being bound by any theory, it is believed that the advantage of a mesh with intraparticle porosity compared to a mesh with interparticle porosity is that the former is more rigid and more resistant to crushing and destruction when force is applied. Intraparticle porosity refers to the pores existing within a (nano)particle. Interparticle porosity refers to pores that exist as a stacking effect of individual particles. Interparticle pores are weaker due to the particle interface and tend to collapse. Intraparticle pores are strong due to the surrounding covalently bonded structure and can withstand high forces and pressures without destruction.

As mentioned above, known reinforcing agents such as carbon black consist of aggregates or agglomerates of spherical particles that can form a three-dimensional structure, but without any covalent bond between the individual particles (not "chemically bonded"), thus having interparticle porosity . To summarize, intraparticle porosity refers to a situation in which the carbon atoms surrounding the pores are covalently bonded, while interparticle porosity refers to the pores found between particles that are physically aggregated, agglomerated, etc.

Since the mesh of the present invention can be considered as one large molecule, there is no need to fuse particles or mesh parts together. Therefore, it is preferable that the porous network of chemically bonded carbon nanofibers be an unfused, intraparticle porous, interconnected carbon nanofiber containing carbon network having intraparticle porosity. In one preferred embodiment, the volume of intraparticle pore space can be characterized as further described below, for example in terms of mercury porosimetry (ASTM D4404-10) or the Brunauer, Emmett and Teller (BET) method (ISO 9277:10).

One skilled in the art will readily understand that the term “chemically interconnected” in a porous, chemically interconnected, carbon nanofiber-containing carbon network implies that the carbon nanofibers are chemically bonded to other carbon nanofibers. It is also implied that a chemical bond is synonymous with a molecular or covalent bond. Typically, those sites where carbon nanofibers join are referred to as junctions or fiber junctions, which can thus conveniently be called “covalent junctions.” These terms are used interchangeably in this text. In the carbon networks of the present invention, compounds are formed by covalently bonded carbon atoms. It follows that the fiber length is defined as the distance between the joints that are connected by the fibrous carbon material.

At least a portion of the fibers in the carbon nanofiber-containing networks of the present invention are crystalline carbon nanofibers. Preferably, at least 20 wt% of the carbon in the carbon networks of the present invention is crystalline, 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.%. Alternatively, the amount of crystalline carbon is 20-90 wt%, more preferably 30-70 wt%, and more preferably 40-50 wt% compared to the total carbon content of the carbon networks of the present invention. Here the term "crystalline" has its usual meaning and refers to the degree of structural order in the material. In other words, the carbon atoms in the nanofibers are to some extent arranged in a regular, periodic manner. Regions or volumes that are crystalline may be referred to as crystallites. Therefore, a carbon crystallite is an individual carbon crystal. A measure of the size of carbon crystallites is the stacking height of the graphite layers. Standard grades of carbon black in accordance with ASTM have a stacking height of graphite layers inside these crystallites in the range of 11-13 Å (angstroms). The carbon nanofiber-containing carbon networks of the present invention have 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 most preferably at least 20 Å. If necessary, carbon networks with crystallites up to 100 Å in size can be produced. Therefore, the carbon networks of the present invention have a stacking height of up to 100 Å, more preferably up to 80 Å, even more preferably up to 60 Å, even more preferably up to 40 Å, and even more preferably up to 30 Å. It is therefore intended that the stacking height of the graphite layers within the crystallites in the carbon networks of the present invention be 15-90 Å, more preferably 16-70 Å, even more preferably 17-50 Å, even more preferably 18-30 Å and most preferably 19-25 Å.

Porous, chemically interconnected carbon networks containing carbon nanofibers can be defined as having chemically interconnected carbon nanofibers, wherein the carbon nanofibers are interconnected through connecting parts, with several (typically 3 or more, preferably 10 or more) nanofibers being covalently interconnected. Said carbon nanofibers are part of the mesh between the joints. The fibers are typically elongated bodies that are solid (i.e., not hollow), preferably having an average diameter or thickness of 1-500 nm, preferably 5-350 nm, more preferably up to 100 nm, in one embodiment 50-100 nm, compared to the average soot particle size of 10-400 nm. In one embodiment, the average fiber length (i.e., the average distance between two connections), determined, for example, using SEM, is preferably in the range of 30-10000 nm, more preferably 50-5000 nm, more preferably 100-5000 nm, and most preferably at least 200-5000 nm.

Nanofibers or structures may preferably be described in terms of an average fiber length to thickness ratio of at least 2, preferably at least 3, more preferably at least 4, and most preferably at least 5, preferably at most 50; which is in sharp contrast to the amorphous (physically bound) aggregates formed from spherical particles obtained through conventional carbon black production.

Carbon nanofiber structures can be defined as carbon networks formed by chemically interconnected carbon nanofibers. Said carbon networks have a three-dimensional configuration in which there is an opening between the carbon nanofibers accessible to a continuous phase, which may be a liquid such as a solvent or aqueous phase, a gas or any other phase. Said carbon meshes have a diameter 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 in all dimensions. Alternatively, said carbon meshes have a diameter of at least 1 µm in two dimensions and at least 5 µm in diameter, preferably at least 10 µm in diameter, more preferably at least 20 µm in diameter and most preferably at least 25 µm in diameter diameter in another dimension. Here, and throughout the text, the term "dimension" is used in the ordinary sense and refers to spatial dimension. There are three spatial dimensions that are orthogonal to each other and define space in its ordinary physical sense. It is further possible that said carbon meshes have a diameter of at least 10 µm in 2 dimensions and at least 15 µm, preferably at least 20 µm, more preferably at least 25 µm, even more preferably at least 30 µm, and most preferably at least 50 µm in diameter in another dimension.

Carbon nanofiber-containing carbon meshes may have a volumetric aggregate size measured using laser diffraction (ISO 13320) or dynamic light scattering analysis of 0.1-100 µm, preferably 1-50 µm, more preferably 4-40 µm, more preferably 5 -35 µm, more preferably 6-30 µm, even more preferably 7-25 µm, and most preferably 8-20 µm.

The carbon nanofiber-containing carbon meshes may have an intraparticle pore diameter, measured using the mercury porosimetry method (ASTM D4404-10), of 5-150 nm, preferably 10-120 nm, and most preferably 10-100 nm.

Carbon nanofiber-containing carbon networks may have an intraparticle volume, measured using the mercury porosimetry method (ASTM D4404-10), of 0.10-1.1 cm ³ /g, preferably 0.51-1.0 cm ³ /g, and most preferably 0.59-0.91 cm ³ /g.

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

Porous, chemically interconnected, carbon nanofiber-containing carbon meshes may also contain carbon black particles embedded as part of the mesh. These particles are mainly found in the junctions between the carbon nanofibers, but may also be present in other parts of the network. The carbon black particles preferably have a diameter that is 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 2 times the diameter of the carbon nanofibers, even more preferably at least 3 times the diameter of the carbon nanofibers, even more preferably at least 4 times the diameter of the carbon nanofibers, and most preferably at least 5 times the diameter of the carbon nanofibers. Preferably, the diameter of the carbon black particles is at most 10 times larger than the diameter of the carbon nanofibers. Such mixed meshes are referred to as hybrid meshes.

Porous, chemically interconnected, carbon nanofiber-containing carbon networks have a functionalized surface. In other words, this surface contains groups that change the hydrophobic nature of the surface, typical of carbon, towards greater hydrophilicity. The surface of carbon networks contains carboxyl groups, hydroxyl groups and phenolic groups. These groups impart some surface polarity and can change the properties of the composite material containing functionalized carbon networks. Without being bound by any particular theory, it is believed that the functionalized groups bind to the elastomer, for example by forming hydrogen bonds, and therefore increase the elasticity of the materials. Consequently, at the very least, the stiffness and durability of the material are altered, which may result in lower rolling resistance and increased service life of the reinforced elastomer, in particular tires or conveyor belts containing said reinforced elastomer.

Porous, chemically interconnected, carbon nanofiber-containing carbon networks may contain metal catalyst nanoparticles. They are traces of the cooking method. These particles can have an average size from 1 nm to 100 nm. Preferably, said particles are monodisperse particles having deviations from their average size within 10%, more preferably within 5%. Non-limiting examples of nanoparticles incorporated into carbon nanofiber-containing carbon networks include noble metals (Pt, Pd, Au, Ag), iron family elements (Fe, Co and Ni), Ru and Cu. Suitable metal complex compounds may be (i) platinum precursors such as H ₂ PtCl ₆ ; H ₂ PtCl ₆ .xH ₂ O; K ₂ PtCl ₄ ; K ₂ PtCl ₄ .xH ₂ O; Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ; Pt(C ₅ H ₇ O ₂ ) ₂ , (ii) ruthenium precursors such as Ru(NO)(NO ₃ ) ₃ ; Ru(dip) ₃ Cl ₂ [dip=4,7-diphenyl-1,10-phenanthroline]; RuCl ₃ , or (iii) palladium precursors such as Pd(NO ₃ ) ₂ , or (iv) nickel precursors such as NiCl ₂ or NiCl ₂ .xH ₂ O; Ni(NO ₃ ) ₂ ; Ni(NO ₃ ) ₂ .xH ₂ O; Ni(CH ₃ COO) ₂ ; Ni(CH ₃ COO) ₂ .xH ₂ O; Ni(AOT) ₂ [AOT=bis(2-ethylhexyl)sulfosuccinate] where x can be any integer selected from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and typically can be equal to 6, 7 or 8.

The porous, chemically interconnected, carbon nanofiber-containing carbon meshes are preferably produced by a process for producing crystalline carbon meshes in a reactor 3 that contains a reaction zone 3b and a termination zone 3c by injecting a water-in-oil microemulsion or a mutually continuous microemulsion c 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 up to 3000° C, more preferably up to 2500°C, most preferably up to 2000°C, for producing crystalline carbon meshes e, transferring these e meshes to the termination zone 3c, and quenching or stopping the formation reaction of the crystalline carbon meshes in the termination zone by sputtering water d.

In a more preferred embodiment, the grids are obtained by the process described above, in which said reactor is a furnace black reactor 3, which contains, along the axis of the reactor 3, a combustion zone 3a, a reaction zone 3b and a termination zone 3c, by generating a hot exhaust gas stream a1 in the combustion zone by burning fuel in oxygen-containing gas b and passing exhaust gas a1 from combustion zone 3a into reaction zone 3b, spraying a water-in-oil microemulsion or mutually continuous microemulsion c containing metal catalyst nanoparticles into reaction zone 3b containing hot exhaust gas, carbonizing said 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 up to 3000°C , more preferably up to 2500°C, most preferably up to 2000°C, and quenching or stopping the reaction in the completion zone 3c by spraying water d to obtain crystalline carbon networks e.

The networks are preferably prepared using the above-described process, further details of which are given below in the section “Process for Preparation of Carbon Nanofiber Containing Carbon Networks” and in FIG. 1A.

The term elastomer is a combination of an elastic material and a polymer. It refers to a material that has viscoelastic properties. This behavior combines viscous behavior—the material exhibits some resistance to deformation when stress is applied—with elastic behavior—the material deforms when stress is applied and returns to its original shape when the stress is removed. Elastomers are commonly called rubbers. These terms are used interchangeably and are used without distinction in this text as in the related art. Elastomers can be cross-linked to increase their elasticity and reduce viscosity. For example, rubbers such as butadiene rubbers and styrene butadiene rubbers (SBR) can be vulcanized. For purposes of the present invention, the term "elastomeric matrix" refers to all elastomers (or rubbers) of the rubber composition. Thus, the elastomeric matrix can in particular consist of one elastomer, but also of a mixture of two or more elastomers.

Reinforced elastomer refers to an elastomer containing an elastomeric matrix supplemented with a reinforcing material, such as a reinforcing filler. Said reinforcing material improves the properties of the elastomer such as abrasion resistance and fatigue resistance in general, as well as rolling resistance, wet grip, snow performance, wear resistance and service life in the case of tires. Examples of the reinforcing filler include carbon black and reinforcing mineral fillers such as silica type fillers, in particular silica (SiO ₂ ), or alumina type fillers, in particular alumina (Al ₂ O ₃ ). The silica used may be any reinforcing silica known to one skilled in the art, in particular any precipitated or fumed silica having a BET specific surface area and a CTAB specific surface area that are both less than 450 m ² /g, preferably from 30 to 400 m ² /g.

The carbon meshes of the present invention function as a reinforcing material. The amount of porous, chemically bonded, crystalline, carbon nanofiber-containing carbon networks 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 usual meaning and refers to the percentage by mass or mass fraction normalized to 100%. It is defined as the amount of a particular component (in this case carbon nanofiber-containing carbon meshes) divided by the amount of all components (in this case the elastomer, including all added materials) and multiplied by 100%. It is generally accepted that 100% refers to all the material that makes up the reinforced elastomer.

Alternatively, the amount of porous, chemically interconnected, crystalline carbon nanofiber structures in the reinforced elastomer may be 10-120 ppm. at 100 m.h. resin, preferably 15-60 ppm. at 100 m.h. resin, more preferably 20-50 parts per part. at 100 m.h. resin, even more preferably 30-50 ppm. at 100 m.h. resin, and most preferably 40-50 ppm. at 100 m.h. resin. Here “m.ch. at 100 m.h. Resin" refers to the number of parts per hundred parts of rubber, which is a common measure in the rubber industry used to indicate the composition of rubber. Here, all ingredients are quantified as parts per part. at 100 m.h. elastomer. Thus, the total amount exceeds 100. For example, a typical rubber may contain 100 ppm. at 100 m.h. rubber resin, 50 m.h. at 100 m.h. soot resin, 30 ppm at 100 m.h. lubricant resin and 20 ppm. at 100 m.h. resins additional additives. In this case, the soot inclusion level is 50 ppm. at 100 m.h. resin or 25 wt.%.

If desired, the porous, chemically interconnected, carbon nanofiber-containing carbon meshes can be mixed with other (conventional) reinforcing fillers. For example, the elastomer can be reinforced by including 10-40 m.p.h. at 100 m.h. soot resin and 10-40 ppm. at 100 m.h. porous, chemically interconnected resins containing carbon nanofibers of carbon networks, more preferably 20-30 parts by weight. at 100 m.h. soot resin and 20-30 ppm. at 100 m.h. Resins are porous, chemically interconnected, carbon nanofiber-containing carbon meshes. Other reinforcing fillers can be added, for example an additional 5-25 ppm. at 100 m.h. silica resins, additional 5-25 ppm. at 100 m.h. alumina resins, or both.

Any carbon black suitable for reinforcing natural rubber can be used in addition to carbon nanofiber-containing carbon meshes for reinforcing elastomers. Non-limiting examples of suitable carbon blacks include: ultra wear resistant furnace black (SAF N110), intermediate SAF 1N220, wear resistant furnace black (HAF N330), easy process channel black (EPC N300), fast extrusion furnace black (FEF N550), high modulus furnace black ( HMF N683), semi-reinforcing furnace black (SRF N770), fine thermal black (FT N880) and medium thermal black (MT N990).

Any precipitated silica suitable for reinforcing natural rubber can be used in addition to carbon nanofiber-containing carbon meshes for reinforcing elastomers. Non-limiting examples of suitable precipitated silica include Ultrasil 7000 and Ultrasil 7005 from Evonik, Zeosil 1165MP, 1135MP and 1115MP from Rhodia, Hi-Sil EZ150G from PPG and Zeopol 8715, 8745 and 8755 from PPG. Huber. When silica is included in an elastomer, it is usually useful to also include a silicone coupling agent.

Reinforcing materials, such as meshes, can be mixed with the elastomeric matrix while it is in a pliable or liquid state until they are uniformly dispersed in said elastomeric matrix. To facilitate transportation and handling, these reinforcing materials may be formulated as tablets, microbeads, beads, granules, or any other suitable compacted form.

If necessary, a coupling agent can be used to provide a strong bond between the reinforcing filler and the elastomer. The use of such an agent is particularly common in combination with siliceous type fillers, but in principle can be used advantageously with any mineral filler. Examples of such coupling fillers include mercapto-functional silanes as well as polysulfide bis-alkoxysilanes.

In addition to reinforcing fillers, which are added primarily to improve the properties of the elastomer and have the added benefit of limiting the cost of the final product, the addition of an inert filler may also be beneficial. Said inert filler does not reinforce the elastomer, and is thus added only to limit or reduce the cost of the final product. The level of inert filler inclusion may be 0-40 wt%, preferably 10-35 wt%, and more preferably 20-30 wt%. This switching level can be 0-80 m.h. at 100 m.h. resin, preferably 20-70 ppm. at 100 m.h. resin, and more preferably 40-60 ppm. at 100 m.h. resin. It is believed that determining the exact levels and selection of filler is within the skill of the person skilled in the art. The inert filler(s) that can be used in accordance with the present invention can be selected from chalk, clay, bentonite, talc, kaolin, glass microbeads, glass flakes, and mixtures thereof. Preferably the inert filler is chalk. Chalk can be in the form of particles having an average size (by weight) of more than 1 micron. The median particle size of the chalk is preferably 0.1-200 µm, more particularly 0.5-30 µm, and even more preferably 1-20 µm. Varieties of chalk known to one skilled in the art are natural calcium carbonates (chalk) or synthetic calcium carbonates with or without a coating (eg, stearic acid).

The elastomer that is reinforced in accordance with the present invention can be any elastomer. Preferably, the use of porous, chemically interconnected, crystalline structures of carbon nanofibers is intended for the reinforcement of butadiene rubbers, most preferably for the reinforcement of styrene butadiene rubber (SBR), ethylene propylene diene monomer rubber (EPDM), natural rubber (NR), vinylidene fluoride monomer rubbers (FKM), perfluoro elastomers (FFKM) and tetrafluoroethylene/propylene rubbers (FEPM), or combinations thereof. Preferably, the elastomer(s) is or contains butadiene rubber, ethylene propylene diene monomer rubber (EPDM), natural rubber (NR), vinylidene fluoride monomer rubbers (FKM), perfluoroelastomers (FFKM) and/or tetrafluoroethylene/propylene rubbers (FEPM). More preferably, the elastomer comprises styrene butadiene rubber (SBR), and even more preferably, the elastomer is styrene butadiene rubber (SBR).

If useful, the reinforced elastomer may contain additional ingredients. For example, the reinforced elastomer may contain a hardener. In sulfur-cured or vulcanizable rubber, the addition of a sulfur donor may be beneficial. Alternatively, peroxides or fluorinated hydrocarbons can be used. In addition, an activator can be added to facilitate vulcanization. In sulfur-curing or vulcanizing rubbers, typical activators are zinc oxide and stearic acid. The activator reinforced elastomer may also contain an accelerating additive such as N-tert-butyl-2-benzothiazyl sulfenamide (TBBS) to accelerate cure.

If it is desired that the final product be a foam, a blowing agent such as sodium bicarbonate may be incorporated into the elastomer. Alternatively, when air pockets or bubbles are undesirable, a desiccant can be added to remove any remaining traces of water.

If the end product is a bonded composite such as a tire, hose or belt, it may be useful to include a bonding agent. Suitable coupling agents may include cobalt-based salts such as cobalt naphthenate or cobalt stearate, as well as proprietary cobalt-boron complex materials.

If it is desired to improve the flexibility of the elastomer at low temperatures, a plasticizer may be added. If desired, the elastomer can be made fire resistant by adding a fire retardant.

The use of porous, chemically interconnected, carbon nanofiber-containing carbon meshes to reinforce elastomers results in a high-quality elastomer that is highly suitable for use in automobile tires or other automotive products, as well as rubber products such as conveyor belts, hoses, rubber linings, axle support gaskets and anti-vibration mounts. Also, the mentioned elastomers can be used as shoes, outsoles and/or door mats.

Application

The above-described use of porous, chemically interconnected, carbon nanofiber-containing carbon networks (or, in other words, porous carbon networks that contain chemically interconnected carbon nanofibers) for reinforcing elastomers provides very high performance reinforced elastomers that can be used in many applications. Therefore, the present invention can also be described as a reinforced elastomer comprising porous, chemically interconnected, carbon nanofiber-containing carbon networks, wherein the incorporation level of the porous, chemically interconnected, carbon nanofiber-containing carbon networks 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.%. Alternatively, the incorporation level of porous, chemically interconnected, crystalline carbon nanofiber structures can be described as 10-120 ppm. at 100 m.h. resin, preferably 10-60 ppm. at 100 m.h. resin, more preferably 20-50 parts per part. at 100 m.h. resin, even more preferably 30-50 ppm. at 100 m.h. resin, and even more preferably 40-50 ppm. at 100 m.h. resin. Networks can be further characterized in terms of crystallinity and intraparticle porosity, as detailed above.

The reinforced elastomer of the present invention is particularly suitable for use in the manufacture of tires and/or rubber products. Therefore, the present invention extends to tires and/or rubber products containing a reinforced elastomer containing porous, chemically interconnected, carbon nanofiber-containing carbon mesh. Here, the tire may be a car tire such as a summer car tire or a winter car tire, a truck tire, a bicycle or motorcycle tire, or any other tire. Industrial rubber products may refer to conveyor belts, tubes, sealing systems, etc. The reinforced elastomer of the present invention can be used in all parts of a tire or rubber product. It is particularly suitable for use in the tread of a tire, that is, the part of the tire that is in contact with the road. In one particularly preferred embodiment, the tire in accordance with the present invention contains reinforced styrene butadiene rubber. Said tires with a reinforced elastomer according to the present invention in the tread have superior properties compared to tires whose tread merely contains carbon black and/or silica.

The properties of tires in accordance with the present invention can be tuned to reduce rolling resistance without compromising wet grip or tread wear/wear resistance/lifetime. Or, if desired, the tires can be tuned to increase the tire's wet grip without compromising flexibility or stiffness. Alternatively, the tire of the present invention may be configured to provide superior winter tire performance without compromising wet traction. Such a tire may even have improved wet grip, as well as improved elongation and reduced stiffness, making it suitable as a winter tire. This is described in more detail in Example 1. Without being bound to any specific theory, these improvements can be attributed to meshes exhibiting low deformation (creep and compression).

Typically, a tire's wet grip (WG) is measured using the ISO4664-1:2011 standard. This conventional method uses tan delta at 0°C as a measure of the tire's wet grip. Preferably, the tan delta at 0°C for the reinforced elastomer in accordance with the present 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.

To evaluate rolling resistance (RRC) according to ISO4664-1:2011, tan delta at 60°C is used as a measure. Preferably, the tan delta at 60°C for the reinforced elastomer in accordance with the present 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.

The tire according to the present invention is very resistant to tread wear. Abrasion resistance, defined as volume loss according to ISO 4649:2010, Method A, is often used to evaluate this property. The reinforced elastomer of the present invention preferably has a volume loss of less than 115 mm ³ , more preferably 110 mm ³ , even more preferably 105 mm ³ , and most preferably 100 mm ³ .

Preferably, the reinforced elastomer according to the present invention has a stiffness measured using a 300% modulus as defined in ISO37:2011. The modulus of the 300% reinforced elastomer according to the present 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 .

The reinforced elastomer according to the present invention preferably has a maximum tensile strength, as defined in ISO37:2011, 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.

Preferably, the elongation at break of the reinforced elastomer according to the present invention, as defined in ISO37:2011, 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%.

The reinforced elastomer according to the present invention preferably has a tensile strength, as defined in ISO34-1:2015, 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.

In one embodiment, meshes are used to reduce heat buildup in the reinforced elastomer.

The reinforced elastomer according to the present invention preferably has a heat storage temperature rise, as defined in 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 one preferred embodiment, the reinforced elastomer exhibiting such heat storage properties is substantially uncompromising in terms of at least one, more preferably at least two, and even more preferably all of tensile strength (ISO37:2011), abrasion resistance (ISO 4649:2010) and rolling resistance (ISO4664-1:2011) as defined above.

The reinforced elastomer according to the present invention preferably has a creep, as defined in ISO 4666-3:2016, of a maximum of 3%, more preferably a maximum of 2.9%, and even more preferably a maximum of 2.6%.

The challenge in developing elastomers is often to improve one property without sacrificing other properties. Carbon meshes address the need to strengthen elastomers while improving or maintaining tan delta at 0°C without compromising tan delta at 60°C and without compromising other properties such as abrasion resistance, 300% modulus, maximum tensile strength, elongation at break and/or tensile strength. When used in a tire tread, it is very useful to have tan delta at 0°C (tire wet grip) high and tan delta at 60°C (rolling resistance) low. Such a tread will make it possible to produce a tire that will have both low rolling resistance, which means more economical fuel consumption, and higher grip of the tire on wet road surfaces, which means increased safety. Therefore, it is preferable that the reinforced elastomer meets at least 4, more preferably at least 5, even more preferably at least 6, and most preferably all of the following characteristics according to embodiment (a) in the table below:

Preferred (a) More preferable (b) Even more preferably (c) Most preferred (d) ISO4664-1:2011, tan delta at 0 (°C) ≥ 0.1250 ≥ 0.1500 ≥ 0.1775 ≥ 0.1800 ISO4664-1:2011, tan delta at 60 (°C) ≤ 0.1350 ≤ 0.1300 ≤ 0.1300 ≤ 0.1275 ISO 4649:2010, volume loss (mm ³ ) < 115 < 115 < 110 < 110 ISO37:2011, maximum tensile strength (MPa) ≥ 22 ≥ 24 ≥ 26 ≥ 28 ISO37:2011 elongation at break (%) ≥ 350 ≥ 400 ≥ 450 ≥ 475 ISO 4666-3:2016, Temperature rise (heat storage) (°C) ≤30 ≤ 29 ≤ 28 ≤ 26 ISO 4666-3:2016, creep (%) ≤ 3 ≤ 2.9 ≤ 2.8 ≤ 2.6

These numbers refer to the properties of reinforced elastomers.

It is especially preferred that the reinforced elastomer meets at least 4, more preferably at least 5, even more preferably at least 6, and most preferably all of the characteristics according to embodiment (b) in the table above.

More preferably, the reinforced elastomer meets at least 4, more preferably at least 5, even more preferably at least 6, and most preferably all of the characteristics according to embodiment (c) in the table above.

Most preferably, the reinforced elastomer meets at least 4, more preferably at least 5, even more preferably at least 6, and most preferably all of the characteristics according to embodiment (d) in the table above.

In one embodiment, meshes are used to improve the electrical conductivity of the reinforced elastomer.

The reinforced elastomer in accordance with the present invention preferably has a volumetric electrical resistivity of preferably less than 10 ⁶ (1000000), which is perceived as static, and the reinforced elastomer exhibiting such improved electrical conductivity is essentially uncompromised in terms of hardness. Its volumetric electrical resistivity is preferably at least one, more preferably at least two orders of magnitude lower than that of traditional carbon black. Preferably, the reinforced elastomer having the advantageous volumetric electrical resistivity characteristic meets at least 4, more preferably at least 5, even more preferably at least 6, and most preferably all of the characteristics in accordance with embodiment (a) or (b) or (c) or (d) in the above table.

The use of carbon mesh to reinforce the elastomers results in a very stiff material with high tensile strength. This means the material is less likely to break down and will therefore last longer. For example, in the case of tires, this can lead to longer lasting tires that are more puncture resistant. The same benefits apply to conveyor belts, which can carry heavier loads without breaking, and which are more energy efficient due to their low rolling resistance. In addition, the reinforced elastomer of the present invention is very suitable for rubber products. The properties described above are suitable in many areas of industrial technology. For example, in the field of conveyor belts, it is very useful to reduce rolling resistance to reduce the power required to drive the belt. Grip on wet surfaces can also be very beneficial as items carried on the belt are less likely to fall off the belt. In addition to this, high abrasion resistance and tensile strength are considered beneficial in the field of conveyor belts. Likewise, the reinforced elastomer according to the present invention is very suitable for use in (industrial) tubing. High abrasion resistance and high tensile strength are also considered beneficial here.

The reinforced elastomer of the present invention can also be used in any of the other applications where rubbers are commonly used. Non-limiting examples of these applications include footwear such as soles and boots, molded rubber parts, grips, plugs, caps, bumpers, diaphragms and shock absorbers.

Process for producing carbon nanofiber-containing carbon meshes

The process for producing porous, chemically interconnected, carbon nanofiber-containing carbon networks can best be described as a modified carbon black process, where by "modified" is meant that a suitable oil, preferably an oil containing at least 14 C atoms (>C14) , such as carbon black feed oil (CBFS), is supplied to the reaction zone of the carbon black reactor as part of a single-phase emulsion, which is a thermodynamically stable microemulsion containing metal catalyst nanoparticles. The emulsion is preferably fed into the reaction zone by spraying, thereby breaking the emulsion into droplets. Although this process can be carried out in a batch or semi-batch manner, the modified carbon black production process is preferably carried out as a continuous process. A single-phase emulsion is a microemulsion containing metal catalyst nanoparticles. The preferred single-phase emulsion contains CBFS oil, and may be referred to as "emulsified CBFS" in the context of the present invention.

The process for producing carbon meshes can be carried out in a reactor 3, which contains a reaction zone 3b and a completion zone 3c, by injecting a single-phase emulsion c, which is a microemulsion containing metal catalyst nanoparticles, preferably a CBFS-containing emulsion, 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 up to 3000°C, more preferably up to 2500°C, most preferably up to 2000 °C, to produce porous, chemically interconnected, carbon nanofiber-containing carbon meshes, transfer these meshes to termination zone 3c, and quench or stop the formation of porous, chemically interconnected, carbon nanofiber-containing carbon meshes in the completion zone by spraying water d. The single-phase emulsion is preferably sprayed into the reaction zone. This is shown in Fig. 1A.

Alternatively, the process for producing porous, chemically interconnected, carbon nanofiber-containing carbon meshes is carried out in a furnace soot reactor 3, which contains, along the axis of the reactor 3, a combustion zone 3a, a reaction zone 3b and a termination zone 3c, by creating a hot exhaust gas stream a1 in combustion zone by burning fuel in oxygen-containing gas b and passing exhaust gas a1 from combustion zone 3a into reaction zone 3b, atomizing (grinding) a single-phase emulsion c according to the present invention, preferably a microemulsion containing metal catalyst nanoparticles, preferably a CBFS-containing emulsion, in reaction zone 3b containing hot off-gas, carbonizing said emulsion at elevated temperatures (above 600°C, preferably above 700°C, more preferably above 900°C, even more preferably above 1000°C, more preferably above 1100° C, preferably up to 3000°C, more preferably up to 2500°C, most preferably up to 2000°C), and quenching or stopping the reaction (ie, the formation of porous, chemically interconnected, carbon nanofiber-containing carbon networks) in the completion zone 3c by spraying water d. Reaction zone 3b contains at least one inlet (preferably a nozzle) for introducing the emulsion, preferably by spraying. This is shown in Fig. 1A.

Residence times of the emulsion in the reaction zone of the furnace carbon black reactor can be relatively short, preferably in the range of 1-1000 ms, and more preferably 10-100 ms. Longer residence times can affect the properties of carbon networks. One example would be the crystallite size, which is higher when longer residence times are used.

According to conventional carbon black production processes, the oil phase may be aromatic and/or aliphatic, preferably containing at least 50 wt.% C14 or higher, more preferably at least 70 wt.% C14 or higher (based on total oil weight). A list of typical oils that can be used to formulate stable emulsions includes, but is not limited to, obtain stable emulsions, carbon black starting oils (CBFS), phenolic oil, anthracene oils, fatty acids (short, medium and long chain), fatty acid esters and paraffins. The oil is preferably C14 or higher. In one embodiment, the oil preferably has high aromaticity. Aromaticity is preferably characterized in terms of the US Bureau of Mines and Geology Correlation Index (BMCI). The oil preferably has a BMCI value >50. In one embodiment, the oil has low aromaticity, preferably a BMCI <15.

CBFS is an economically attractive oil source in the context of the present invention and is preferably a mixture of heavy hydrocarbons containing predominantly C14 - C50, the total amount of C14 - C50 preferably being at least 50 wt.%, and more preferably at least 70 wt.% of the original raw materials. Some of the most important feedstocks used to produce carbon black include clarified slurry oil (CSO) obtained from the fluid catalytic cracking of gas oils, ethylene cracking residues from naphtha steam cracking, and coal oils. The presence of paraffins (<C15) significantly reduces their suitability and higher aromaticity is preferred. The concentration of aromatic compounds determines the rate at which carbon nuclei are formed. The carbon black feedstock preferably has a high BMCI value to be able to provide high yield with minimal heat input, thereby reducing production cost. In one preferred embodiment, and according to current CBFS specifications, the oil, including blends of oils, has a BMCI value greater than 120. While one skilled in the art should have no difficulty understanding what is a suitable CBFS, simply As a guide, it should be noted that from a yield point of view, the BMCI value of CBFS is preferably greater than 120, and even more preferably greater than 132. The amount of asphaltene in the oil is preferably less than 10 wt.%, and more preferably less than 5.0 wt. % by weight CBFS. CBFS is preferably low in sulfur because sulfur has a negative impact on product quality, reduces yield, and is corrosive to equipment.

Preferably, the sulfur content of the oil according to ASTM D1619 is less than 8.0 wt%, preferably less than 4.0 wt%, and more preferably less than 2.0 wt%.

The emulsion, preferably the CBFS-containing emulsion, is a "single-phase emulsion", which means that the oil phase and the water phase optically appear as one soluble mixture in which the physical separation of oil, water or surfactant is invisible to the naked eye. A single-phase emulsion may be a macroemulsion or a microemulsion, and may be kinetically or thermodynamically stable. The process by which the emulsion completely breaks down (coalescence), i.e. the system separates into bulk oil and aqueous phases, is generally thought to be controlled by four different droplet loss mechanisms, i.e. Brownian flocculation, foaming, sedimentation flocculation and disproportionation.

"Stable single-phase emulsion" in the context of the present invention means that the emulsion does not show physical separation visible to the eye, which is preferably reflected in terms of the emulsion not showing a change in pH value of more than 1.0 units. pH values, and/or that the emulsion does not show a change in viscosity of more than 20% over a period of time exceeding the production time of the carbon mesh. The term "stable" can mean "thermodynamically stable" or "kinetically stable" (with the addition of energy, i.e. with mixing). In practice, a single-phase emulsion is considered stable if no separation is optically noticeable, that is, the single-phase state is maintained for at least 1 minute after preparation of the emulsion. Thus, it is preferable for the emulsion to maintain its pH within 1.0 pH. pH and/or its viscosity with a variation of less than 20% over a period of at least 1 minute, preferably at least 5 minutes after preparation. Although increased stability is preferred for handling purposes, it should be noted that for the production process it may still be advantageous to use emulsions that are stable for relatively short periods of time of 1 min, preferably 5 min: by adding energy (stirring), the stability of the emulsion can be increased increased, and short-term stability can be increased by in-line mixing. Although macroemulsions are not thermodynamically stable and will always revert to their original, immiscible separate oil and water phases, the rate of breakdown can be low enough to make them kinetically stable throughout the production process.

As long as a stable single-phase emulsion is obtained, the amounts of water and oil are not considered limiting, but it should be noted that lower amounts of water (and higher amounts of oil) improve yields. The water content is typically 5-50% by weight of the emulsion, preferably 10-40% by weight, even more preferably up to 30% by weight, and more preferably 10-20% by weight of the emulsion. Although you can consider using more water, it will come at the expense of yield. Without being bound by any particular theory, the present inventors believe that the aqueous phase determines the shape and morphology of the networks thus obtained.

The choice of surfactant(s) is not considered a limiting factor as long as the combination of oil, water and surfactant(s) results in a stable microemulsion as defined above. As further guidance to the skilled person, it should be noted that the surfactant may be selected based on the hydrophobicity or hydrophilicity of the system, ie hydrophilic-lipophilic balance (HLB). The HLB of a surfactant is a measure of its degree of hydrophilicity or lipophilicity, determined by calculating values for different regions of the molecule according to the Griffin or Davis 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 one skilled in the art based on the requirements of maintaining a thermodynamically stable single-phase emulsion as defined above. It has been found that an emulsion containing more than 50 wt.% oil, preferably having less than 30 wt.% aqueous phase, can best be stabilized by a surfactant having an HLB value greater than 7, preferably greater than 8, more preferably greater than 9, and most preferably above 10. On the other hand, an emulsion containing at most 50 wt.% oil may best be stabilized with a surfactant having an HLB value below 12, preferably below 11, more preferably below 10, most preferably below 9. in particular below 8. The surfactant is preferably selected so that it is compatible with the oil phase. Where the oil is an emulsion containing CBFS, a highly aromatic surfactant is preferred, while an oil with a low BMCI value, eg BMCI < 15, is best stabilized using aliphatic surfactants. The surfactant(s) may be cationic, anionic or nonionic, or a mixture thereof. One or more nonionic surfactants are preferred to increase yield since there will be no residual ions left in the final product. In order to obtain a clean off-gas stream, it is preferable that the surfactant structure has a low sulfur and nitrogen content, and preferably does not contain sulfur and nitrogen. Non-limiting examples of typical nonionic surfactants that can be used to formulate stable emulsions include the commercially available Tween, Span, Hypermer, Pluronic, Emulan, Neodol, Triton X and Tergitol series.

In the context of the present invention, a microemulsion is a dispersion consisting of water, oil (preferably CBFS) and surfactant(s), which is a single optically and thermodynamically stable liquid with dispersed domain diameters ranging from approximately 1 to 500 nm, preferably from 1 to 100 nm, and typically from 10 to 50 nm. In a microemulsion, the dispersed phase domains are either globular (that is, droplets) or interconnected (forming a mutually continuous microemulsion). In one preferred embodiment, the surfactant tails form a continuous network in the oil phase of a water-in-oil (w/o) or cross-continuous emulsion. The water domains should contain a metal catalyst, preferably having an average particle size of 1-100 nm.

The single-phase emulsion, that is, a w/o emulsion or a cross-continuous microemulsion, preferably a cross-continuous microemulsion, further contains metal catalyst nanoparticles, preferably having an average particle size of 1-100 nm. One skilled in the art will find detailed guidance in the field of carbon nanotubes (CNTs) for the production and use of these types of nanoparticles. These metal nanoparticles were found to improve network formation in terms of speed and yield as well as reproducibility. Methods for the production of suitable metal nanoparticles are described in the publications of 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.

Nanoparticle metal catalyst is used in a cross-continuous or w/o microemulsion, preferably containing CBFS in a cross-continuous or w/o microemulsion. In one embodiment, a mutually continuous microemulsion is most preferred. Preferably, in said (mutually continuous) microemulsion, the uniformity of the metal particles is controlled by mixing a first (mutually continuous) microemulsion, in which the aqueous phase contains a metal complex salt capable of being reduced into the final metal particles, and a second (mutually continuous) microemulsion, in wherein the aqueous phase contains a reducing agent capable of reducing said metal complex salt; when mixed, the metal complex is reduced, thus forming metal particles. The controlled environment of the (mutually continuous) emulsion stabilizes the particles against sintering or Ostwald ripening. The size, concentration and durability of the catalyst particles can be easily controlled. Adjusting the average metal particle size within the above range is considered routine experimentation, for example by changing the molar ratio of metal precursor to reducing agent. Increasing the relative amount of reducing agent produces smaller particles. The metal particles thus obtained are monodisperse, and deviations from the average particle size are preferably within 10%, more preferably within 5%. In addition, the present technology places no restrictions on the actual metal precursor provided it can be reduced. Non-limiting examples of nanoparticles incorporated into carbon nanofiber-containing carbon networks include noble metals (Pt, Pd, Au, Ag), iron family elements (Fe, Co and Ni), Ru and Cu. Suitable metal complex compounds may be (i) platinum precursors such as H ₂ PtCl ₆ ; H ₂ PtCl ₆ .xH ₂ O; K ₂ PtCl ₄ ; K ₂ PtCl ₄ .xH ₂ O; Pt(NH ₃ ) ₄ (NO ₃ ) ₂ ; Pt(C ₅ H ₇ O ₂ ) ₂ , (ii) ruthenium precursors such as Ru(NO)(NO ₃ ) ₃ ; Ru(dip) ₃ Cl ₂ [dip=4,7-diphenyl-1,10-phenanthroline]; RuCl ₃ , or (iii) palladium precursors such as Pd(NO ₃ ) ₂ , or (iv) nickel precursors such as NiCl ₂ or NiCl ₂ .xH ₂ O; Ni(NO ₃ ) ₂ ; Ni(NO ₃ ) ₂ .xH ₂ O; Ni(CH ₃ COO) ₂ ; Ni(CH ₃ COO) ₂ .xH ₂ O; Ni(AOT) ₂ [AOT=bis(2-ethylhexyl)sulfosuccinate] where x can be any integer selected from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and is usually equal to 6, 7 or 8. Non-limiting suitable reducing agents include hydrogen gas, sodium borohydride, sodium bisulfate, hydrazine or hydrazine hydrate, ethylene glycol, methanol and ethanol. Citric acid and dodecylamine are also suitable. The type of metal precursor is not an essential part of the present invention. The metal of the (mutually continuous) microemulsion particles is preferably selected from the group consisting of Pt, Pd, Au, Ag, Fe, Co, Ni, Ru and Cu, as well as mixtures thereof, to control the morphology of the carbon network structures ultimately formed. Metal nanoparticles eventually become embedded within these structures and physically attach to them. Although there is no minimum concentration of metal particles at which these networks are formed—in fact, the networks are formed using a modified carbon black production process in accordance with the present invention—yield has been found to increase with increasing concentration of metal particles. In one preferred embodiment, the active metal concentration is at least 1 mM, preferably at least 5 mM, more preferably at least 10 mM, even more preferably at least 15 mM, even more preferably at least 20 mM, in particular at least 25 mM, and most preferably up to 3500 mM, preferably up to 3000 mM. In one embodiment, the metal nanoparticles are present in amounts up to 250 mM. These are the catalyst concentrations relative to the amount of aqueous phase (mutually continuous) microemulsion.

Atomization of the single-phase emulsion, preferably containing CBFS emulsion, is preferably carried out by atomization using a nozzle system 4, which allows droplets of the emulsion to contact the hot off-gas a1 in the reaction zone 3b, leading to conventional carbonation, network formation and subsequent agglomeration to obtain carbon networks according to with the present invention. The injection step preferably includes elevated temperatures above 600°C, preferably 700-3000°C, more preferably 900-2500°C, and most preferably 1100-2000°C.

In one aspect, the porous, chemically interconnected, carbon nanofiber-containing carbon networks preferably have at least one, preferably at least two, more preferably at least three, and most preferably all of the following properties:

(i) Iodine adsorption number (IAN) 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 according to the standard ASTM D1510. Alternatively, the IAN value is 30-1000 mg/g, preferably 100-800 mg/g, and more preferably 30-500 mg/g according to ASTM D1510;

(ii) Nitrogen surface area (N2SA) of at least 30 m ² /g, preferably at least 50 m ² /g, more preferably at least 100 m ² /g, and most preferably at least 150 m ² /g in accordance with ASTM D6556 standard. Alternatively, the N2SA value is 30-1000 m ² /g, preferably 100-800 m ² /g, and more preferably 30-500 m ² /g in accordance with ASTM D6556;

(iii) Statistical thickness of surface area (STSA) of at least 40 m ² /g, more preferably at least 70 m ² /g, even more preferably at least 100 m ² /g, even more preferably at least 125 m ² /g, and most preferably at least 150 m ² /g in accordance with ASTM D6556. Alternatively, the STSA value is 40-1000 m ² /g, preferably 100-800 m ² /g, and more preferably 120-500 m ² /g in accordance with ASTM D6556;

(iv) Oil absorption number (OAN) 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 at least 125 cc/100 g, and most preferably at least 150 cc/100 g according to ASTM D2414. Alternatively, the OAN value is 50-500 cc/100 g, and preferably 150-350 cc/100 g according to ASTM D2414,

Where:

IAN=Iodine Adsorption Number: The number of grams of iodine adsorbed per kilogram of soot under specified conditions, as defined in ASTM D1510;

N2SA=nitrogen surface area: the total surface area of soot, which is calculated from nitrogen adsorption data using BET theory in accordance with ASTM D6556;

STSA=Statistical Surface Area Thickness: The outer surface area of the soot which is calculated from nitrogen adsorption data using de Boer theory and the soot model according to ASTM D6556; And

OAN=Oil Absorption Number: The number of cubic centimeters of dibutyl phthalate (DBP) or paraffin oil absorbed by 100 g of carbon black under specified conditions. The OAN value is proportional to the degree of aggregation of the soot structural level, determined in accordance with ASTM D2414.

For each of IAN, N2SA (or NSA), STSA, and OAN—all typical parameters for characterizing carbon blacks—the porous, chemically interconnected, carbon nanofiber-containing carbon networks exhibit superior properties compared to traditional carbon blacks. Porous, chemically interconnected, carbon nanofiber-containing carbon networks are preferably characterized by at least one, preferably at least two, and more preferably all of (i), (ii) and (iii), as these are typical ways to characterize surface area properties of materials . In one embodiment, the porous, chemically interconnected, carbon nanofiber-containing carbon networks exhibit at least one of properties (i), (ii) and (iii), and additionally correspond to property (iv).

Example: Properties of carbon meshes in SBR

The performance of styrene butadiene rubber reinforced with carbon meshes in accordance with the present invention (“carbon meshes”) was compared with the performance of rubbers reinforced with a known brand of carbon black available from Cabot Corporation (N115). Carbon meshes were used that were prepared similar to the manufacturing process of Example 1 in patent document WO2018/002137, the contents of which are incorporated herein by reference. These meshes had an average intraparticle pore diameter measured using mercury porosimetry (ASTM D4404-10) of 20 nm. Commercially, such SBR compounds are used as reinforced components, in tire casings, or in industrial rubbers. Performance was evaluated in accordance with ASTM D3191, which describes formulation, processing, and test methods for evaluating and controlling carbon black production. The standards used to measure the properties of elastomeric compounds are listed in Table 1.

The compounds were prepared by mixing Europrene 1502 in an amount of 100 ppm. at 100 m.h. resin, carbon mesh or soot in an amount of 50 ppm. at 100 m.h. resin, 3 parts at 100 m.h. zinc oxide resin, 1 part. at 100 m.h. stearic acid resin, 1.75 parts. sulfur per 100 ppm resin, and 1 part. TBBS at 100 m.h. resin. The main ingredients were mixed in stages: at time t=0 min: add all Europrene, at time t=1 min: add 50% carbon mesh or carbon black, zinc oxide and stearic acid, at time t=2:30 min: add the remaining 50% of carbon mesh or soot, at time t=4 min: sweep, and at time t=5 min, dump. The rotor rotation speed was constant and amounted to 75 rpm. The initial temperature was 50°C and the discharge temperature was approximately 160°C. The load factor of the mixer (Banbury type, 1.6 liters, manufactured by Farrel Bridge) was 70%. The curing agents (sulfur and TBBS) were further mixed into the compound using a two-roll mill (1 L capacity, Agila) at 50°C. Test samples were cured at 160°C in electrically heated Fontijne Holland presses and conditioned for 24 hours before testing at 23°C.

These reinforced elastomers were tested in accordance with the standards shown in Table 1. The test results are shown in Table 2. In Table 2 it can be noted that the carbon meshes in accordance with the present invention have a high tan delta at 0°C in combination with a low tan delta at 60°C, which means improved rolling resistance [RRC] combined with wet grip [WG] without compromising other key characteristics such as abrasion resistance (measured as volume loss), tensile strength and elongation. Therefore, the carbon mesh of the present invention allows the production of products such as tires or conveyor belts having low rolling resistance, resulting in reduced energy costs without compromising other properties. The carbon mesh of the present invention allows the production of tires or conveyor belts that are more reliable, stronger and less prone to breaking when elongated.

Table 1: Standards used to measure the properties of elastomeric compounds.

Property Standard Tan delta at 0°C ISO4664-1:2011 Tan delta at 60°C ISO4664-1:2011 Loss of volume ISO 4649:2010 method A Maximum tensile strength ISO37:2011 Elongation at break ISO37:2011 Temperature increase ISO 4666-3:2016 Creep ISO 4666-3:2016

Table 2: Properties of elastomeric compounds

Property Tan delta at 0°C
(WG) Tan delta at 60°C
(RRC) Volume loss
[mm ³ ] Maximum tensile strength
[MPa] Elongation
upon rupture
[%] Temperature rise (heat accumulation)
[°C] Creep
[%] N115 0.1866 0.1441 108 27.4 457 33.7 3.3 Carbon meshes 0.1852 0.1272 108 28.9 503 25.6 2.5

The same carbon meshes were also found to reduce bulk electrical resistivity performance by 3 orders of magnitude at the same hardness levels as N115:

Table 3: Volume resistivity

Quantity [m.h. at 100 m.h. resin] Shore A hardness Volume resistivity [Ohm.cm] N115 50 66 10 ⁺⁶ (1000000) Carbon meshes 60 67 10 ⁺³ (1000)

Example: Properties of carbon networks in natural rubber (NR)

The performance of natural rubber reinforced with carbon meshes in accordance with the present invention (“carbon mesh”) was compared with the performance of rubbers reinforced with a known brand of carbon black available from Cabot Corporation (N115, N550). Carbon meshes were used that were prepared similar to the manufacturing process of Example 1 in patent document WO2018/002137, the contents of which are incorporated herein by reference. These meshes had an average intraparticle pore diameter measured using mercury porosimetry (ASTM D4404-10) of 20 nm. Commercially, such NR compounds are used as reinforced components, in tire tread or in industrial rubbers. Performance was evaluated in accordance with ASTM D3192, which describes formulation, processing, and test methods for evaluating and controlling carbon black production. The standards used to measure the properties of elastomeric compounds are listed in Table 1.

The compounds were prepared by mixing TSR-10 in an amount of 100 ppm. at 100 m.h. resin, carbon mesh or soot in an amount of 50 ppm. at 100 m.h. resin, 5 parts at 100 m.h. zinc oxide resin, 3 parts. at 100 m.h. stearic acid resin, 2.5 parts. sulfur per 100 ppm resin, and 0.6 m.p. MBTS at 100 m.h. resin. The main ingredients were mixed in stages: at time t=0 min: add all NR, at time t=1 min: add 50% carbon mesh or carbon black, zinc oxide and stearic acid, at time t=2:30 min: add the remaining 50% of carbon mesh or soot, at time t=4 min: sweep, and at time t=5 min, dump. The rotor rotation speed was constant and amounted to 75 rpm. The initial temperature was 50°C and the discharge temperature was approximately 160°C. The load factor of the mixer (Banbury type, 1.6 liters, manufactured by Farrel Bridge) was 70%. The curing agents (sulfur and MBTS) were further mixed into the compound using a two-roll mill (1 L capacity, Agila) at 50°C. Test samples were cured at 160°C in electrically heated Fontijne Holland presses and conditioned for 24 hours before testing at 23°C.

These reinforced elastomers were tested according to the standards shown in Table 4.

The test results are shown in Table 5. In Table 5, it can be noted that the carbon meshes in accordance with the present invention have a lower tan delta at 60°C in combination with improved tensile strength, elongation and tensile strength. Therefore, the carbon mesh of the present invention allows the production of products such as tires or conveyor belts having low rolling resistance, resulting in reduced energy costs without compromising other properties. The carbon mesh of the present invention allows the production of tires or conveyor belts that are more reliable, stronger and less prone to breaking when elongated. In addition, performance was compared with N550 (carbon black, Carbot Corporation), commonly used in hoses, for example. The results in Table 6 suggest improved flexibility and abrasion resistance.

Table 4: Standards used to measure the properties of elastomeric compounds.

Property Standard Tan delta at 60°C ISO4664-1:2011 Volume loss ISO 4649:2010 method A Maximum tensile strength ISO37:2011 Elongation at break ISO37:2011 Tensile strength ISO 34-1:2015

Table 5. Tensile properties, hysteresis in NR (ASTM D3192) at the same abrasion resistance.

Tensile strength
[MPa] Elongation
[%] Tensile strength at 23C
[kN/m] Abrasion resistance (volume loss)
[mm ³ ] Tanδ at 60C N115 28.2 592 94 153 0.1075 Carbon meshes 29.0 616 104 155 0.1057

Table 6. Improvement of abrasion resistance and mechanical properties for hose applications.

Carbon meshes N550 Tensile Strength(MPa) 27.7 25.7 Elongation (%) 522 488 Mod100 [MPa] * 2.7 3.2 Mod300 [MPa] * 13.6 14.9 MRI* 5.04 4.66 Abrasion resistance [mm ³ ] 125 148 Mooney Viscosity [MU] 57 62

* Mod100 - voltage required to elongate the sample by 100%; Mod300 is the voltage required to elongate the sample by 300%; MRI=MOD300/MOD100.

Claims (13)

1. The use of a porous carbon network, which contains chemically interconnected carbon nanofibers, for the reinforcement of elastomers, in which the carbon network has intraparticle porosity, and in which the carbon nanofibers are interconnected with other carbon nanofibers in the network by chemical bonds at their intersections, and the pores in the network have the diameter of the intraparticle pores is 5-150 nm as determined by mercury porosimetry, at least 20 wt.% of the carbon in the carbon networks is in crystalline form, and the carbon nanofibers have an average length to fiber thickness ratio of at least 2. 2. Application according to claim 1, in which the level of inclusion of the carbon mesh in the reinforced elastomer is 1-60 wt.% or 10-120 wt.h. per 100 parts by weight polymer. 3. Application according to claim 1 or 2, in which the average length of carbon nanofibers is 30-10000 nm. 4. Use as claimed in any one of the preceding claims, wherein the reinforced elastomer is used in tires or rubber products. 5. Use according to any of the preceding claims to reduce heat buildup in the reinforced elastomer. 6. Use according to any of the preceding claims to improve the electrical conductivity of the reinforced elastomer. 7. Reinforced elastomer for the manufacture of tires or rubber products, containing 10-60 wt.% or 10-120 wt.h. per 100 parts by weight a polymer of a porous carbon network that contains chemically interconnected carbon nanofibers, in which the carbon network has intraparticle porosity, and in which the carbon nanofibers are interconnected with other carbon nanofibers in the network by chemical bonds at their intersections, and the pores in the network have an intraparticle pore diameter of 5-150 nm as determined by mercury porosimetry, wherein at least 20 wt.% of the carbon in the carbon networks is in crystalline form, and the carbon nanofibers have an average length to fiber thickness ratio of at least 2. 8. Application according to any one of paragraphs. 1-6 or the reinforced elastomer according to claim 7, wherein the reinforced elastomer meets at least 4, more preferably at least 5, even more preferably at least 6, and most preferably all of the following characteristics in accordance with the table below: tire grip on wet road surfaces, tan delta at 0 (°C) ≥ 0.1250 rolling resistance, tan delta at 60 (°C) ≤ 0.1350 abrasion resistance, volume loss (mm ³ ) < 115 modulus 300%, maximum tensile strength (MPa) ≥ 22 elongation at break (%) ≥ 350 temperature rise (heat accumulation) (°C) ≤ 30 creep (%) ≤ 3 9. Application according to any one of paragraphs. 1-6 and 8 or a reinforced elastomer according to any one of paragraphs. 7, 8, wherein the reinforced elastomer meets at least 4, more preferably at least 5, even more preferably at least 6, and most preferably all of the following characteristics in accordance with the table below: tire grip on wet road surfaces, tan delta at 0 (°C) ≥ 0.1500 rolling resistance, tan delta at 60 (°C) ≤ 0.1300 abrasion resistance, volume loss (mm ³ ) < 115 modulus 300%, maximum tensile strength (MPa) ≥ 24 elongation at break (%) ≥ 400 Temperature rise (heat accumulation) (°C) ≤ 29 creep (%) ≤ 2.9 10. Reinforced elastomer according to any one of paragraphs. 7-9, in which the carbon mesh is obtained by a method for producing crystalline carbon meshes in a reactor 3, which contains a reaction zone 3b and a completion zone 3c, by injecting a water-in-oil microemulsion or a mutually continuous microemulsion c containing nanoparticles metal catalyst 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 up to 3000°C, more preferably up to 2500°C, most preferably up to 2000°C, producing crystalline carbon meshes e, moving these meshes e to the termination zone 3c, and quenching or stopping the crystalline carbon mesh forming reaction in the termination zone by spraying water d. 11. Finished product containing a reinforced elastomer according to any one of paragraphs. 7-10, which is a tire or rubber product selected from seals, gaskets, conveyor belts, tubes, hoses, rubber pads, axle bearing gaskets and anti-vibration mounts.

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