Regenerated carbon black, rubber composition and tire

Abstract

The problem addressed by the present disclosure is to provide: a regenerated carbon black capable of obtaining a rubber composition having excellent damage resistance and capable of improving reinforcement characteristics; a rubber composition containing the regenerated carbon; [Solution] The present invention relates to a regenerated carbon black having a particle diameter (D90) of 310 nm or less at a cumulative volume fraction of 90% as measured in accordance with JIS K 6217-6: 2008, a nitrogen adsorption specific surface area of 50 m2 / g or more and 85 m2 / g or less, and a relative tinting strength of 55 or more as measured in accordance with JIS K 6217-5, and a tire manufactured from the rubber composition.

Description

Technical Field

[0001] The present disclosure relates to recycled carbon black obtained by recovering from waste. The present disclosure also relates to a rubber composition using the recycled carbon black, and a tire obtained by using the rubber composition. Background Art

[0002] In recent years, in order to achieve a sustainable society, research on recycling and sustainable materials has been actively carried out. Research on the recycling and effective utilization of waste tires has also been carried out. In particular, it is important to regenerate carbon black from waste tires as a useful material. As a method for regenerating carbon black from waste tires, the thermal decomposition treatment described in PLT 1 to 3 can be mentioned.

[0003] Incidentally, the recycled carbon black recovered by recycling (hereinafter referred to as "recycled carbon black") contains metal components, inorganic components, organic components, etc. contained in tires as impurities. When recycled carbon black is used in rubber production, it is well known that various mechanical properties such as reinforcement properties and fracture resistance properties are reduced due to the influence of impurities compared with non-recycled carbon black (so-called "virgin" carbon black). Various investigations have been carried out to suppress such a decrease in physical properties.

[0004] For example, PLT 1 discloses a method for producing recycled carbon black that can improve reinforcement properties when co-mixed in a rubber composition by uniformly and effectively thermally decomposing polymer-based waste such as rubber materials.

[0005] PLT 2 discloses that the abrasion resistance and processability of a rubber composition are improved by using recycled carbon black having a zinc compound content not greater than a given value.

[0006] In addition, PLT 3 discloses the production of carbon black from rubber decomposition oil generated by thermally decomposing rubber waste. It is disclosed that the ash content of the carbon black of PLT 3 is 0.1 to 10% by mass, and the fracture resistance property of the rubber composition is improved by using such carbon black.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] PLT 1: JP 2012-162672 A

[0010] PLT 2: JP 2012-1682 A

[0011] PLT 3: JP 2017-8223 A Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] The present disclosure is made in view of the above problems, and an object thereof is to provide recycled carbon black capable of producing rubber and tires having improved reinforcing properties while maintaining damage resistance.

[0014] Another object of the present disclosure is to provide a rubber composition containing recycled carbon black and a tire produced from the rubber composition.

[0015] Solutions to the problems

[0016] To solve the above problems, the present disclosure provides the following [1] to [5].

[0017] [1] A recycled carbon black having a particle size (D90) at which the cumulative volume percentage measured according to JIS K 6217-6:2008 reaches 90% of 310 nm or less, a nitrogen adsorption specific surface area of 50 m 2 / g or more and 85 m 2 / g or less, and a relative coloring power measured according to JIS K6217-5 of 55 or more.

[0018] [2] The recycled carbon black according to [1], having a carbon content of 85% by mass or more and 97% by mass or less.

[0019] [3] The recycled carbon black according to [1] or [2], having an ash content of 0.5% by mass or more and 10% by mass or less.

[0020] [4] The recycled carbon black according to any one of [1] to [3], obtained from a pyrolysis residue generated by thermally decomposing a rubber product containing carbon black.

[0021] [5] A rubber composition containing the recycled carbon black according to any one of [1] to [4].

[0022] [6] A tire containing the rubber composition according to [5].

[0023] Effects of the invention

[0024] According to the present disclosure, recycled carbon black capable of producing a tire having improved reinforcing properties while maintaining damage resistance can be obtained. In addition, a tire having improved reinforcing properties while maintaining damage resistance can be obtained by using a rubber composition containing recycled carbon black. Detailed description

[0025] [Recycled carbon black]

[0026] The recycled carbon black of the present disclosure has a particle size (D90) at which the cumulative volume percentage measured according to JIS K 6217-6:2008 reaches 90% of 310 nm or less, a nitrogen adsorption specific surface area of 50 m2 85 m or more per g 2 55 or more in relative coloring power measured according to JIS K6217-5. By using the recycled carbon black having the above physical properties, a tire having improved reinforcing properties while maintaining destructibility can be obtained.

[0027] In the present disclosure, "recycled carbon black" means carbon black obtained by recycling carbon black from waste materials that have undergone recycling. The waste materials that have undergone recycling mentioned above refer to rubber products containing carbon black represented by waste rubber and waste tires. "Recycled carbon black" is different from carbon black directly produced from hydrocarbons such as petroleum or natural gas, that is, non-recycled carbon black. It should be noted that "waste" in this context includes not only materials discarded after actual use but also materials discarded after being manufactured but not actually used.

[0028] In addition, the recycled carbon black of the present disclosure is obtained from pyrolysis residues generated by pyrolyzing rubber products containing carbon black. When a rubber product containing carbon black is pyrolyzed, pyrolysis residues and volatile components (oil) are generated, and recycled carbon black can be recovered from either of them. However, the recycled carbon black of the present disclosure does not include carbon black recovered from oil.

[0029] In addition to carbon black, the pyrolysis residues obtained by pyrolyzing waste materials such as waste rubber and waste tires also contain ash. The ash is derived from non-volatile components contained in rubber and tires. Therefore, the recycled carbon black obtained from the pyrolysis residues has a relatively low carbon black content. On the other hand, in view of various physical properties required for tires produced using recycled carbon black, the higher the carbon content, the more preferable. In the recycled carbon black of the present disclosure, the carbon content is preferably 85% by mass or more, more preferably 87% by mass or more, even more preferably 89% by mass or more, and still more preferably 91% by mass or more. The upper limit of the carbon content in the recycled carbon black of the present disclosure is preferably 97% by mass. Therefore, the carbon content of the recycled carbon black of the present disclosure is preferably 85% by mass or more and 97% by mass or less, more preferably 87% by mass or more and 97% by mass or less, even more preferably 89% by mass or more and 97% by mass or less, and still more preferably 91% by mass or more and 97% by mass or less. It should be noted that the above carbon content does not include the value of adsorbed moisture.

[0030] Specifically, the ash contains zinc oxide, zinc sulfide, silicon dioxide, iron compounds (iron oxide), calcium oxide, aluminum oxide, magnesium oxide, etc. In the case of recycled carbon black produced from the pyrolysis residue obtained by pyrolyzing waste, even when various processes for removing ash are carried out, a certain amount of ash remains. In the present disclosure, the recycled carbon black may contain ash. The lower limit of the ash content in the recycled carbon black of the present disclosure may be 0.5% by mass. On the other hand, in view of the physical properties required for tires and the quality of recycled carbon black, etc., the ash content contained in the recycled carbon black is preferably 10% by mass or less, more preferably 6.5% by mass or less, and even more preferably 5.0% by mass or less. Therefore, the ash content in the recycled carbon black of the present disclosure is preferably 0.5% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 6.5% by mass or less, and even more preferably 0.5% by mass or more and 5.0% by mass or less.

[0031] Since the amount of impurities contained in the volatile components is small, the recycled carbon black recovered from the volatile components (oil) generated by pyrolysis has a low ash content and a relatively high carbon content. Non-recycled carbon black produced from hydrocarbons as raw materials (hereinafter, sometimes referred to as "ordinary carbon black") also has a high carbon content. The carbon content of these carbon blacks is about 98% by mass or more (excluding adsorbed moisture). Therefore, the recycled carbon black of the present disclosure can be said to be different from ordinary carbon black and is recycled carbon black produced by a different manufacturing method.

[0032] The recycled carbon black of the present disclosure requires that the particle size (D90) at which the cumulative volume percentage measured according to JIS K 6217-6:2008 (disc type centrifugal sedimentation method) reaches 90% be 310 nm or less. If D90 is greater than 310 nm, it is impossible to obtain rubber with sufficient destructibility. D90 is preferably 305 nm or less, more preferably 295 nm or less, and even more preferably 200 nm or less.

[0033] In addition, the recycled carbon black of the present disclosure requires that the nitrogen adsorption specific surface area (N2SA) be 50 m 2 / g or more and 85 m 2 / g or less.

[0034] If the nitrogen adsorption specific surface area is less than 50 m 2 / g, it is impossible to obtain rubber with sufficient destructibility. In view of the destructibility, the nitrogen adsorption specific surface area is preferably 57 m 2 / g or more, more preferably 65 m 2 / g or more.

[0035] Generally, as the particle size of carbon black decreases, the nitrogen adsorption specific surface area tends to increase. By using carbon black having a large nitrogen adsorption specific surface area, it becomes possible to obtain rubber excellent in destructiveness resistance. However, when the nitrogen adsorption specific surface area of recycled carbon black is higher than 85 m 2 / g, the rolling resistance of the rubber tends to decrease. The nitrogen adsorption specific surface area of the recycled carbon black is preferably 80 m 2 / g or less.

[0036] The nitrogen adsorption specific surface area of the recycled carbon black of the present disclosure is preferably 57 m 2 / g or more and 85 m 2 / g or less, more preferably 65 m 2 / g or more and 85 m 2 / g or less, and even more preferably 65 m 2 / g or more and 80 m 2 / g or less.

[0037] It should be noted that the nitrogen adsorption specific surface area (N2SA) is a value measured according to ISO 4652-1.

[0038] In addition, the recycled carbon black of the present disclosure requires a relative coloring power of 55 or more measured according to JIS K 6217-5. The relative coloring power is one of the parameters related to the particle size and specific surface area of carbon black. When the relative coloring power is less than 55, sufficient destructiveness resistance cannot be obtained. The relative coloring power is preferably 60 or more, more preferably 65 or more, even more preferably 70 or more, and particularly preferably 80 or more.

[0039] [Manufacturing method of recycled carbon black]

[0040] The recycled carbon black of the present disclosure is produced from pyrolysis residues generated by pyrolyzing rubber products containing carbon black.

[0041] The manufacturing method of the recycled carbon black of the present disclosure includes a step of pyrolyzing a rubber product containing carbon black and a step of obtaining recycled carbon black from the pyrolysis residues.

[0042] In the present disclosure, the rubber product containing carbon black as a raw material is, for example, a waste tire. The waste tire is preferably those collected from large vehicles such as trucks and buses, or from passenger cars.

[0043] The rubber product can be pre-crushed before the pyrolysis step.

[0044] In the pyrolysis step, pyrolysis of the rubber product containing carbon black can be carried out using known equipment. For example, fuel, nitrogen, and the rubber product are introduced into a pyrolysis furnace, and pyrolysis is carried out. As a result of this pyrolysis step, pyrolysis residues and volatile components are generated from the rubber product.

[0045] After the thermal decomposition step, the pyrolysis residue and the volatile components are separated by known methods. The volatile components are cooled to become oil (pyrolysis oil).

[0046] The pyrolysis residue after separation is collected, and impurities such as zinc oxide, silica, and iron compounds (iron oxide) are removed from the pyrolysis residue to recover recycled carbon black. Known methods can be used as the method for removing impurities.

[0047] [Rubber composition]

[0048] The rubber composition of the present disclosure can be a rubber composition commonly used in tire production as long as it contains the above-mentioned recycled carbon black. Each component will be described below.

[0049] [Rubber component]

[0050] In the rubber composition of the present disclosure, the type of rubber is not particularly limited. Examples include natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), butyl rubber (IIR), ethylene-propylene-diene copolymer (EPDM), acrylonitrile-butadiene copolymer (NBR), and rubbers obtained by combining these.

[0051] [Filler]

[0052] The rubber composition of the present disclosure contains a filler for reinforcing the rubber composition.

[0053] In the present disclosure, the rubber composition contains the above-mentioned recycled carbon black. The compounding amount of the recycled carbon black in the rubber composition can be appropriately adjusted according to the part of the tire to which the resulting rubber is applied. For example, the compounding amount of the recycled carbon black can be adjusted in the range of 1 to 150 parts by mass per 100 parts by mass of the rubber component.

[0054] By using the rubber composition containing the recycled carbon black of the present disclosure, the destructibility resistance of the tire can be improved, and the reinforcing property can be improved.

[0055] In the present disclosure, in addition to the above-mentioned recycled carbon black, the rubber composition may further contain ordinary carbon black. When ordinary carbon black is used, its grade is not particularly limited. From the viewpoint of promoting the use of recycled materials, it is preferable that the compounding amount of ordinary carbon black is as low as possible, and it is particularly preferable that no ordinary carbon black is contained. In addition, it is preferable that the compounding amount of ordinary carbon black is less than that of recycled carbon black. However, depending on the specifications required for the rubber product, the compounding amount of ordinary carbon black may be higher than that of recycled carbon black. For example, the compounding amount of ordinary carbon black can be adjusted within the range of 0 to 150 parts by mass per 100 parts by mass of the rubber component. In this case, the mass ratio of ordinary carbon black to recycled carbon black (ordinary carbon black / recycled carbon black) is preferably in the range of 95 / 5 to 0 / 100.

[0056] The rubber composition of the present disclosure may also include silica or an inorganic filler other than silica as a filler. The type of filler other than carbon black and the compounding amount of each filler can be appropriately selected according to the part of the tire to which it is applied.

[0057] In the present disclosure, the type of silica is not particularly limited, and examples include wet silica (hydrated silica), dry silica (anhydrous silica), calcium silicate, aluminum silicate, and among them, wet silica is preferred. These types of silica can be used alone or in combination of two or more types.

[0058] In addition, in the present disclosure, the physical properties of the silica used, such as the BET specific surface area and the cetyltrimethylammonium bromide specific surface area (CTAB), are not particularly limited and can be appropriately selected according to the performance of the tire obtained from the rubber composition.

[0059] In addition, the compounding amount of silica in the rubber composition is not particularly limited and can be appropriately selected according to the performance required for the tire.

[0060] In the present disclosure, the type of inorganic filler is not particularly limited, and for example, clay, talc, calcium carbonate, and aluminum hydroxide can be used. These inorganic fillers can be appropriately selected in view of their various physical properties.

[0061] <Various components>

[0062] The rubber composition used in the present disclosure may contain various components commonly used in the rubber industry as needed within the range that does not impair the effects of the present disclosure. Examples of such components include stearic acid, anti-aging agent, zinc oxide, vulcanizing agent, vulcanization accelerator, resin, oil, and silane coupling agent.

[0063] [Tire]

[0064] The tires of the present disclosure are manufactured using a rubber composition containing the above-mentioned recycled carbon black. In particular, the rubber composition of the present disclosure is preferably applied to, but not limited to, treads, tread bases, sides, inner liners, beads, and bead fillers, etc. By using the recycled carbon black of the present disclosure, the damage resistance of the tires can be improved, and the reinforcing properties can also be improved.

[0065] Compounds other than recycled carbon black described in this specification may be partially or wholly derived from fossil resources, biological resources such as plant resources, or recycled resources such as waste tires. Alternatively, they may be derived from a mixture of two or more of fossil resources, biological resources, and recycled resources.

[0066] Examples

[0067] [Production of Rubber for Raw Materials]

[0068] Mix the respective components according to the formulation listed in Table 1 below to prepare a rubber composition. The mixing is carried out in two stages. Table 1 outlines the amounts of the respective components blended in each mixing stage. The units of the values in the formulation of Table 1 are parts by mass. The prepared rubber composition is vulcanized at 145 °C to produce rubber for raw materials.

[0069] [Table 1]

[0070]

[0071] Details of the components in Table 1 are as follows.

[0072] NR: Natural rubber, RSS#3

[0073] CB1: Carbon black, Seast 3 manufactured by Tokai Carbon Co., Ltd.

[0074] CB2: Carbon black, Seast F manufactured by Tokai Carbon Co., Ltd.

[0075] CB3: Carbon black, N660

[0076] Stearic acid: Kiri-jirushi stearic acid manufactured by NOF Corporation

[0077] Wax: Santite A manufactured by Seiko Chemical Co., Ltd.

[0078] Zinc oxide: Two types of zinc oxide manufactured by HakusuiTec Co., Ltd.

[0079] Antioxidant 1: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd.

[0080] Antioxidant 2: NONFLEX RD manufactured by Seiko Chemical Co., Ltd.

[0081] Vulcanization accelerator 1: Sanceler CM-G manufactured by Sanshin Chemical Industry Co., Ltd.

[0082] Sulfur: HK200-5 manufactured by Hosoi Chemical Industry Co., Ltd.

[0083] Retarder: Retarder CTP manufactured by Toray Fine Chemicals Co., Ltd.

[0084] [Production of recycled carbon black]

[0085] Recycled carbon blacks 2 to 7 are produced using raw material rubbers A and B through the following steps.

[0086] Raw material rubber A or raw material rubber B is put into a metal container purged with nitrogen. Subsequently, the metal container is placed in an electric furnace heated to the temperature outlined in Table 2, and thermal decomposition is carried out under a nitrogen stream. The oil generated by thermal decomposition during heating is collected with a trap, and heating is stopped when the generation of oil visually ceases. After heating is stopped, the system is cooled to room temperature, and the metal container is taken out of the electric furnace to stop thermal decomposition. The residue inside the metal container is collected to obtain recycled carbon blacks 2 to 7.

[0087] As recycled carbon black 1, a commercially available recycled carbon black produced by thermal decomposition was prepared.

[0088] In Table 2, "recycled carbon black" is abbreviated as "r-CB".

[0089] [Evaluation of recycled carbon black]

[0090] 1. Particle size distribution

[0091] Measurement samples are taken from recycled carbon blacks 1 to 7. The particle size distribution of each sample is measured according to JIS K6217-6:2008 (disc centrifuge sedimentation method). As the measurement device, a BI-DCP particle size analyzer manufactured by Brookhaven Instruments is used. From the obtained particle size distribution, the particle diameter (D90) at which the cumulative volume percentage reaches 90% is obtained. The results are outlined in Table 2. In Table 2, the decimal point is rounded off.

[0092] 2. Nitrogen adsorption specific surface area

[0093] The nitrogen adsorption specific surface area of recycled carbon blacks 1 to 7 was measured according to ISO 4652-1. The results are summarized in Table 2. In Table 2, the decimal points are rounded off.

[0094] 3. Relative tinting strength

[0095] The relative tinting strength of recycled carbon blacks 1 to 7 was obtained by conducting measurements according to JIS K 6217-5 and adjusting using a calibration curve and a correction factor. The results are summarized in Table 2. In Table 2, the decimal points are rounded off.

[0096] 4. Carbon content and ash content

[0097] The carbon content of recycled carbon blacks 1 to 7 was measured by thermogravimetric analysis (TGA).

[0098] The sample was heated from room temperature to 550 °C in a nitrogen atmosphere and then further heated in an air atmosphere to maintain 550 °C, and the weight loss was measured. The weight loss (mass %) during heating from room temperature to 550 °C in a nitrogen atmosphere was defined as "weight loss 1", and the weight loss (mass %) during heating while maintaining 550 °C in an air atmosphere was defined as "weight loss 2". Weight loss 2 was regarded as the carbon content. The ash content was calculated by the following formula:

[0099] Ash content (mass %) = 100 - weight loss 1 - weight loss 2

[0100] The results are summarized in Table 2. In Table 2, the carbon content is expressed to the first decimal place. The ash content is expressed with two significant figures.

[0101] [Table 2]

[0102]

[0103] As described in Table 2, the D90 of recycled carbon black 1 (r-CB1, commercially available recycled carbon black) is large. In addition, the ash content of recycled carbon black 1 is greater than those of recycled carbon blacks 2 to 7 (r-CB2 to 7).

[0104] The nitrogen adsorption specific surface area of recycled carbon black 2 is small. Recycled carbon blacks 3 to 7 satisfy that D90 is 310 nm or less and the nitrogen adsorption specific surface area is in the range of 50 m 2 / g or more and 85 m 2 / g or less, and also satisfy that the relative tinting strength is 55 or more.

[0105] [Production of rubber using recycled carbon black]

[0106] Mix the respective components according to the formulation listed in Table 3 below to prepare a rubber composition. The mixing is carried out in two stages. Table 3 outlines the amounts of the respective components blended in each mixing stage. The values in the formulation of Table 3 are in parts by mass. The prepared rubber composition is vulcanized at 145 °C to obtain the rubbers of the examples and comparative examples.

[0107] Details of the components in Table 3 are as follows.

[0108] SBR: Styrene-butadiene rubber, SBR1500

[0109] r-CB1 to 7: The above-mentioned recycled carbon black 1 to 7

[0110] Stearic acid: Kiri-jirushi stearic acid manufactured by NOF Corporation

[0111] Wax: Santite A manufactured by Seiko Chemical Co., Ltd.

[0112] Antioxidant 1: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd.

[0113] Antioxidant 2: NONFLEX RD manufactured by Seiko Chemical Co., Ltd.

[0114] Zinc oxide: Two types of zinc oxide manufactured by HakusuiTec Co., Ltd.

[0115] Vulcanization accelerator 2: Soxinol D manufactured by Sumitomo Chemical Co., Ltd.

[0116] Vulcanization accelerator 3: Sanceler NS-G manufactured by Sanshin Chemical Industry Co., Ltd.

[0117] Vulcanization accelerator 4: Sanceler DM-TG manufactured by Sanshin Chemical Industry Co., Ltd.

[0118] Sulfur: HK200-5 manufactured by Hosoi Chemical Industry Co., Ltd.

[0119] [Performance Evaluation of Vulcanized Rubber]

[0120] 1. Destructive resistance

[0121] The tensile strength (TB) was measured by subjecting the vulcanized rubbers of each example and comparative example to a tensile test at room temperature according to JIS K6251:2017. The destructibility was expressed as an index with the tensile strength of the test piece of Comparative Example 1 regarded as 100 according to the following formula:

[0122] Destructibility index = (tensile strength of the test piece other than Comparative Example 1 / tensile strength of the test piece of Comparative Example 1) × 100.

[0123] The higher the destructibility index, the more resistant the vulcanized rubber is to destruction and the more excellent the destructibility is. The results are summarized in Table 3.

[0124] 2. Reinforcement characteristics

[0125] The tensile strength (TB) was measured by subjecting the vulcanized rubbers of each example and comparative example to a tensile test at room temperature according to JIS K6251:2017. Using the tensile strength of the vulcanized rubbers of each example and comparative example at 300% strain, the reinforcement characteristics were expressed based on Comparative Example 1 using the following formula:

[0126] Reinforcement characteristics index = (tensile strength of the test piece other than Comparative Example 1 at 300% strain / tensile strength of the test piece of Comparative Example 1 at 300% strain) × 100.

[0127] The higher the reinforcement characteristics index, the better the reinforcement characteristics. The results are summarized in Table 3.

[0128] [Table 3]

[0129]

[0130] When the destructibility is 100 or more and the reinforcement characteristics are 160 or more, the sample is judged as "qualified".

[0131] As described in Table 3, Examples 1 to 5 using recycled carbon black (Recycled Carbon Black 3 to 7) satisfying D90 of 310 nm or less, nitrogen adsorption specific surface area of 50 m 2 / g or more and 85 m 2 / g or less, and relative coloring power of 55 or more satisfy a destructibility index of 100 or more and reinforcement characteristics of 160 or more. In other words, it can be understood that the destructibility of Examples 1 to 5 is equal to or higher than that of Comparative Example 1, while having significantly improved reinforcement characteristics.

[0132] On the other hand, in Comparative Example 2 using recycled carbon black 2 with a small nitrogen adsorption specific surface area, the reinforcement characteristics cannot be sufficiently improved.

Claims

1. A recycled carbon black, having a particle size (D90) at which the cumulative volume percentage measured according to JIS K 6217-6:2008 reaches 90% of 310 nm or less, The nitrogen adsorption specific surface area is 50 m 2 / g or more and 85 m 2 / g or less, and and having a relative coloring power measured according to JIS K 6217-5 of 55 or more.

2. The recycled carbon black according to claim 1, having a carbon content of 85% by mass or more and 97% by mass or less.

3. The recycled carbon black according to claim 1 or 2, having an ash content of 0.5% by mass or more and 10% by mass or less.

4. The recycled carbon black according to claim 1 or 2, obtained from pyrolysis residues generated by thermally decomposing a rubber product containing carbon black.

5. A rubber composition comprising the recycled carbon black according to claim 1 or 2.

6. A tire comprising the rubber composition according to claim 5.

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