Modified thermal cracking carbon black, and preparation method and application thereof

Abstract

The present application relates to the technical field of carbon black modification, and provides modified thermal cracking carbon black, a preparation method and application thereof, the preparation method comprises mixing a modification liquid with thermal cracking carbon black, and performing heat treatment on the mixture in an oxygen-free environment to obtain modified thermal cracking carbon black, wherein the modification liquid is prepared by dissolving alpha-diketone and beta-diketone in a solvent. The alpha-diketone and beta-diketone in the modification liquid cooperatively modify the thermal cracking carbon black, the beta-diketone inhibits aging by forming a six-membered ring chelate with metal ions, the alpha-diketone forms an interface layer by thermal grafting after being adsorbed and enriched by the beta-diketone, and the interface layer repairs and reinforces and physically isolates; when used alone, the reinforcing and aging resistance cannot be considered together, but when the two are compounded, the reinforcing efficiency can be restored or even exceed that of the original carbon black, and the comprehensive performance meets the requirements of the sidewall rubber.

Description

Technical Field

[0001] This invention relates to the field of carbon black modification technology, and more specifically to a modified pyrolysis carbon black, its preparation method, and its application. Background Technology

[0002] Waste tires can be recycled through pyrolysis, producing pyrolysis oil, pyrolysis gas, and pyrolysis carbon black (also known as recycled carbon black or rCB). Pyrolysis carbon black accounts for approximately 30%-40% of the products and is an important secondary resource. If it can be applied to rubber products, especially tire sidewalls and triangle rubber parts, the circular economy value of waste tires will be significantly enhanced, dependence on virgin carbon black will be reduced, and carbon emissions will be lowered.

[0003] However, the direct application of existing pyrolysis carbon black in rubber compositions suffers from several prominent drawbacks, severely limiting its ability to replace virgin carbon black at a high proportion. These drawbacks are mainly reflected in the following aspects: Firstly, the problem of metal ion-catalyzed aging. Existing technologies mostly employ acid washing or alkali washing for deashing (e.g., the invention patent with announcement number CN103540172A discloses a two-acid reaction and one-alkali washing process for deashing). While this can reduce some ash content, the improvement in aging performance is limited. Secondly, the improvement in reinforcing performance is limited. Existing modification technologies mainly employ mechanical grinding, coupling agent treatment, or polymer encapsulation. For example, patent announcement number CN111471216A uses a hydroxylation modifier combined with carbon fiber and a coupling agent to surface modify pyrolysis carbon black. Patent announcement number CN110878148B removes organic impurities and dissolves some inorganic ash through alkali washing and polymer encapsulation with rubber latex. Patent announcement number CN111500092A utilizes ultrasonic curing of organic solvents to adsorb surface tar oil. These methods improve dispersibility or reduce ash content to some extent, but they are not effective in reconstructing surface active sites, and the reinforcing performance is still difficult to approach the level of native N550 or N330 carbon black.

[0004] Therefore, existing technologies still need further improvement. Summary of the Invention

[0005] To address the shortcomings of existing technologies and solve the aforementioned problems, a modified pyrolysis carbon black, its preparation method, and its applications are proposed, and the following technical solution is provided: A method for preparing modified pyrolytic carbon black includes mixing a modifying liquid with pyrolytic carbon black, and then heat-treating the mixture in an oxygen-free environment to obtain modified pyrolytic carbon black. The modifying liquid is prepared by dissolving α-diketone and β-diketone in a solvent.

[0006] Furthermore, the mass ratio of the α-diketone to the β-diketone is 5-12:2-6.

[0007] Furthermore, the total amount of the α-diketone and β-diketone used is 5-15% of the mass of the pyrolytic carbon black.

[0008] Furthermore, the total amount of the α-diketone and β-diketone used is 4-7% of the mass of the pyrolytic carbon black.

[0009] Furthermore, the α-diketone is an alicyclic α-diketone; the β-diketone is a fused-ring aromatic β-diketone.

[0010] Further, the α-diketone includes at least one of camphorquinone or 1,2-cyclohexanedione; the β-diketone includes at least one of 1,3-indanedione, 2-methyl-1,3-indanedione, or benzo[1,3]dioxacyclopenten-5-yl-β-diketone.

[0011] Further, the preparation method of the modified liquid includes: heating the solvent to 40-70°C, adding β-diketone under stirring to obtain a β-diketone solution, cooling the β-diketone solution to 30-50°C, and then adding α-diketone under light-protected conditions to obtain the modified liquid; Furthermore, the solvent is at least one of naphthenic oil, liquid polybutadiene, aromatic oil, and environmentally friendly rubber filler oil.

[0012] Furthermore, the pyrolysis carbon black is pore-forming with an alkaline solution and washed with an acidic solution until neutral before mixing.

[0013] Furthermore, the alkaline solution includes at least one of potassium hydroxide solution and sodium hydroxide solution; the acidic solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0014] Furthermore, the mixing process involves spraying the modified liquid onto the surface of the pyrolytic carbon black in an atomized form for 10-15 minutes.

[0015] Furthermore, the heat treatment process involves heating to 120-140℃, holding and stirring for 45-60 minutes, and then cooling to 40-60℃ after stirring.

[0016] A modified pyrolysis carbon black prepared according to the above preparation method.

[0017] An application of the above-mentioned modified pyrolysis carbon black is its use in rubber sidewall rubber, the preparation process of which is as follows: After plasticizing styrene-butadiene rubber, antioxidants, activators and plasticizers are added for a first-stage mixing. After the first-stage mixing, the rubber is discharged to obtain a first-stage compound. The modified pyrolysis carbon black is coated on the surface of the first-stage compound and left to stand. Then, vulcanizing agents and accelerators are added for a second-stage mixing. After the second-stage mixing, the rubber is discharged to obtain a second-stage compound, which is then vulcanized to obtain the rubber sidewall rubber.

[0018] Furthermore, the settling time is 4-20 hours.

[0019] Furthermore, during the first-stage mixing, the rotation speed is 45-55 rpm, the first-stage mixing time is 120-180s, and the discharge temperature is 130-140℃.

[0020] During the two-stage mixing process, the rotation speed is 30-40 rpm, the mixing time is 180-240 s, the discharge temperature is 90-100℃, and the two-stage compound is obtained by cooling to room temperature after discharge.

[0021] During the vulcanization process, the vulcanization temperature is 145-160℃, the vulcanization pressure is 8-12 MPa, and the vulcanization time is 15-30 min.

[0022] Due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are as follows: 1. In this application, α-diketone and β-diketone in the modified liquid synergistically modify thermally decomposed carbon black. β-diketone inhibits aging by forming a six-membered ring chelate with metal ions. α-diketone is enriched by adsorption of β-diketone and then thermally grafted to form an interface layer, which repairs, reinforces and physically isolates the carbon black. When used alone, reinforcement and aging resistance cannot be achieved at the same time. The combination of the two can restore the reinforcement efficiency to or even surpass that of virgin carbon black. The comprehensive performance meets the requirements of tire sidewall rubber.

[0023] 2. The ash content of pyrolysis carbon black contains a large amount of Zn. 2+ Fe 3+ Cu 2+ These transition metal ions act as catalysts for rubber aging, causing premature embrittlement, discoloration, and cracking of the tire sidewall rubber. β-diketones form stable six-membered ring chelates with these metal ions, locking in their "toxic activity." The tensile strength retention rate significantly recovers after thermo-oxidative aging, extending tire lifespan.

[0024] 3. The surface of pyrolytic carbon black is covered with pyrolytic carbon deposits, resulting in extremely low surface energy and weak interfacial bonding with rubber molecular chains. Directly replacing conventional carbon black cannot meet the mechanical support requirements of tire sidewall rubber. Free radicals generated from the pyrolysis of α-diketone are grafted onto the carbon black surface, forming an organic-inorganic interfacial transition layer, which improves the wettability of the filler to the rubber and the content of the binder. The tensile stress at a given elongation is restored to a level close to that of virgin carbon black.

[0025] 4. The slow release of low-molecular-weight polycyclic aromatic hydrocarbons (PAHs) and sulfides remaining in the micropores of pyrolysis carbon black causes tires to emit an unpleasant burnt odor, which is unacceptable for passenger cars, especially new energy vehicles. 1,3-Indanedione has a large conjugated plane that can penetrate and block micropores during high-temperature treatment. It physically adsorbs residual small molecules through π-π stacking, inhibiting the volatilization of odor molecules, thus significantly reducing the odor level of the rubber compound and meeting the requirements for low-odor environmentally friendly tires. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application.

[0027] Unless otherwise specified in the examples, standard conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products. Unless otherwise specified, all reagents used in the examples are commercially available.

[0028] A method for preparing modified pyrolytic carbon black includes mixing a modifying liquid with pyrolytic carbon black, followed by heat treatment in an oxygen-free environment to obtain modified pyrolytic carbon black. The modifying liquid is prepared by dissolving α-diketones and β-diketones in a solvent. β-diketones preferentially anchor to the carbon black surface and micropores due to the π-π stacking effect of polycyclic aromatic hydrocarbons, and on the one hand, they interact with Zn in the ash. 2+ Fe 3+ Cu 2+ The formation of stable six-membered ring chelates by metal ions inhibits metal catalytic aging at its source. Furthermore, it eliminates odor by adsorbing and sealing residual PAHs within the pores. α-Diketones accumulate in the hydrophobic adsorption microdomains constructed by β-diketones, undergoing efficient free radical grafting reactions during heat treatment to form an organic-inorganic interface transition layer on the carbon black surface. This not only significantly repairs and reinforces the activity but also forms a physical barrier against internal metal ions. While using only α-diketones can restore some degree of tensile stress through surface grafting, the lack of metal passivation leads to a rapid deterioration of performance after long-term thermo-oxidative aging. Additionally, α-diketones are prone to sublimation at high temperatures, resulting in low grafting efficiency and insufficient odor sealing depth. Conversely, using only β-diketones can effectively complex metal ions and significantly reduce odor, but the lack of a chemical grafting layer means the carbon black-rubber interface remains primarily based on weak physical adsorption, resulting in limited recovery of reinforcing properties and failing to meet the stringent requirements for stiffness and dynamic fatigue in tire sidewall rubber. Only through synergistic compounding of the two can the efficiency of reinforcement be increased, the problems of odor and process stability be solved, and the inherent defects of single components being neglected in one aspect can be made up for.

[0029] The mechanism of the modified liquid in this case is as follows: The surface structure of pyrolytic carbon black resembles disordered graphite, consisting of 3-4 layers of graphite-like microcrystals formed by stacked hexagonal carbon rings. Its surface and micropore walls are richly covered with aromatic ring conjugated systems. β-Diketones, especially those with fused benzene ring structures, possess complete large π-conjugated planes. According to the adsorption theory of aromatic compounds on carbonaceous surfaces, strong adsorption occurs between aromatic rings through π-π electron donor-acceptor (EDA) interactions, with the adsorption effect being particularly significant in fused ring systems. Therefore, β-Diketones, due to their fused-ring aromatic structure, form π-π stacking with the graphite microcrystals on the carbon black surface, preferentially and firmly anchoring themselves to the carbon black surface and micropore entrances, constructing hydrophobic aromatic microregions on the carbon black surface. Simultaneously, the 1,3-dicarbonyl group in the β-Diketone molecule can form an enol anion through keto-enol tautomerism, which reacts with residual Zn in the ash. 2+ Fe 3+ Cu 2+ When transition metal ions form stable six-membered ring metal chelates, they are locked at lattice sites, thus inhibiting their catalytic effect on rubber aging at the source. After the solvent evaporates, the aromatic micro-regions formed by β-diketone on the carbon black surface act as an adsorption enrichment layer, providing anchoring sites for α-diketone and altering its distribution and retention efficiency on the carbon black surface.

[0030] α-Diketones contain two directly adjacent carbonyl groups (-CO-CO-), with a relatively weak C-C bond. During heat treatment at 120-140℃ in an anaerobic environment, this bond undergoes homolytic cleavage, generating acyl radicals. These radicals can then be grafted in situ onto the carbon black surface under thermomechanical and chemical action. The carbon black surface contains oxygen-containing functional groups such as phenolic hydroxyl, carboxyl, and quinone groups, and its surface edges also contain free radicals and unpaired electrons. These active sites can effectively capture free radicals, achieving chemical grafting. Without β-diketones to construct aromatic microdomains, the affinity of α-diketones for the carbon black surface is weak, and they will largely sublimate and be lost during heat treatment at 120-140℃. The actual proportion of α-diketones participating in grafting is very low, severely limiting the grafting efficiency. When β-diketones are pre-anchored on the carbon black surface via π-π stacking, their aromatic ring system adsorbs and enriches α-diketones through intermolecular π-π interactions. This significantly increases the local concentration of α-diketones in the near-surface region of the carbon black, thereby greatly reducing their high-temperature sublimation loss and ensuring that the free radicals generated by pyrolysis can efficiently graft onto the active sites on the carbon black surface. The specific chemical process of grafting is as follows: acyl free radicals generated by the pyrolysis of α-diketones attack the carbon black surface and react with surface phenolic hydroxyl / carboxyl groups. The acyl free radicals abstract hydrogen atoms from the phenolic hydroxyl or carboxyl groups, or directly couple with oxygen-centered free radicals to form ester bonds (-CO-O-) or ether bonds (-COC-), covalently bonding the alicyclic skeleton of α-diketones to the carbon black surface. Direct coupling with surface free radical sites: The edges of carbon black-like graphite layers themselves contain dangling bonds and free radical sites, and acyl free radicals can directly couple with these sites to form C-C bonds for grafting. Reaction with surface quinone / ketone groups: The quinone and ketone groups on the carbon black surface can capture free radicals, undergoing addition or coupling reactions to form new oxygen-containing cross-linked structures. These covalent grafts construct chemical bridges between the carbon black and the subsequent rubber matrix, rather than simply physical adsorption.

[0031] After α-diketone radical grafting, a covalently anchored organic-inorganic interface transition layer is formed on the carbon black surface. This interface layer acts as a secondary physical barrier, given that the β-diketone has already complexed and passivated most of the metal ions. Even if a very small number of incompletely complexed metal ions attempt to migrate to the carbon black surface, they will be blocked by this covalently grafted organic interface layer, preventing them from contacting the rubber molecular chains and thus cutting off the diffusion path of metal ions catalyzing rubber aging. The surface of pyrolysis carbon black is chemically inert due to pyrolysis carbon deposition, resulting in weak interfacial bonding with the rubber molecular chains. The covalently bonded interface layer formed by α-diketone grafting changes the filler-matrix interaction mode—from weak physical adsorption to chemical bonding—restoring the tensile stress and tensile strength to levels close to those of virgin carbon black.

[0032] If only α-diketones are used, without the π-π anchoring and enrichment effect of β-diketones, α-diketones will be largely sublimated and lost during high-temperature heat treatment, resulting in extremely low actual grafting rates and large batch-to-batch variations. Simultaneously, the metal ions are not complexed and passivated, leaving Zn residues inside the carbon black. 2 + Fe 3+ During long-term use, rubber undergoes continuous catalytic aging reactions, and its performance deteriorates rapidly after thermo-oxidative aging. If only β-diketone is used, it can effectively improve the dispersibility and aging resistance of carbon black through π-π stacking and metal complexation. However, the carbon black-rubber interface is still mainly based on weak physical adsorption, without a chemical graft layer to provide strong interfacial bonding. The recovery of tensile stress and tear strength is limited, and it cannot meet the stiffness support and dynamic fatigue requirements of the tire sidewall rubber.

[0033] In summary, the synergistic effect of α-diketone and β-diketone can achieve complementary functions such as β-diketone site enrichment, complexation and passivation, odor suppression and α-diketone free radical grafting and interfacial bonding, thus solving the triple defects of low reinforcing efficiency, severe catalytic aging and strong odor in pyrolysis carbon black.

[0034] The mass ratio of α-diketone to β-diketone is 5-12:2-6. The relatively high amount of α-diketone ensures sufficient free radical grafting density on the carbon black surface, restoring the reinforcing properties to near the level of virgin carbon black. The moderate amount of β-diketone effectively complexes metal ions and seals micropores while preventing excessive β-diketone from migrating and precipitating during rubber vulcanization, thus avoiding interference with the crosslinking network. This ratio achieves an optimal balance between reinforcement recovery and aging protection performance.

[0035] The total amount of α-diketone and β-diketone used is 5-15% of the mass of thermally decomposed carbon black.

[0036] Within this range, the dosage of α-diketone and β-diketone ensures that the modifier forms a complete coating layer on the carbon black surface and is sufficient to complex most of the harmful metal ions in the ash, thus ensuring the effectiveness of the modification; it also prevents excessive organic small molecules from migrating and precipitating during subsequent rubber processing and use, avoiding negative impacts on the appearance, adhesion properties, and dynamic fatigue properties of rubber products.

[0037] The α-diketone is an alicyclic α-diketone; the β-diketone is a fused-ring aromatic β-diketone. Alicyclic α-diketones have a rigid cyclic skeleton and excellent thermal stability, and are not easily volatilized or lost at heat treatment temperatures of 120-140℃, allowing them to continuously generate free radicals to complete interfacial grafting. Fused-ring aromatic β-diketones (such as 1,3-indanedione) have large π-conjugated planes, which on the one hand strongly adsorb onto the carbon black surface through π-π stacking, resulting in a firmly bonded modified layer; on the other hand, their high enol content leads to a fast metal complexation rate, strong chelate stability, and more effective embedding and sealing of carbon black micropores, significantly reducing odor.

[0038] Preferably, the α-diketone comprises at least one of camphorquinone or 1,2-cyclohexanedione; the β-diketone comprises at least one of 1,3-indanedione, 2-methyl-1,3-indanedione, or benzo[1,3]dioxacyclopenten-5-yl-β-diketone. Camphorquinone and 1,2-cyclohexanedione are widely available and cost-effective, while 1,3-indanedione and its derivatives are mature commercial reagents. This group of compounds showed the highest recovery rate of reinforcing properties, the most thorough metal passivation, and the most significant odor suppression in experiments.

[0039] The preparation method of the modified liquid includes: heating the solvent to 40-70℃, adding β-diketone under stirring to obtain a β-diketone solution, cooling the β-diketone solution to 30-50℃, and adding α-diketone in the dark to obtain the modified liquid. The step-by-step temperature control, adding β-diketone first and then α-diketone, and operating in the dark effectively solves the preparation problem caused by the difference in thermal stability between the two diketones. First, the thermally stable β-diketone is dissolved at a higher temperature, and then the photothermally sensitive α-diketone is added at a lower temperature and under dark conditions, avoiding premature thermal decomposition or photo-induced polymerization side reactions of the α-diketone during the preparation process, ensuring the chemical integrity and activity retention of the two active components in the modified liquid.

[0040] The pyrolysis carbon black is pore-forming with an alkaline solution and washed with an acidic solution until neutral before mixing.

[0041] The mixing process involves spraying the modified liquid into the surface of pyrolysis carbon black in an atomized form for 10-15 minutes. Atomized spraying allows the modified liquid to contact the powdered carbon black in the form of tiny droplets, resulting in a large contact area and uniform coating. This effectively avoids carbon black clumping and uneven distribution of the modifier caused by directly pouring the liquid. The 10-15 minute spraying time ensures that the modified liquid is fully absorbed by the carbon black while preventing excessive solvent evaporation due to prolonged spraying, thus ensuring the uniformity of the coating layer.

[0042] The heat treatment process involves heating to 120-140℃, holding at this temperature with stirring for 45-60 minutes, and then cooling to 40-60℃. The 120-140℃ temperature range falls within the thermal free radical initiation temperature range of alicyclic α-diketones, which can drive the grafting reaction of α-diketones while preserving the structural integrity of β-diketones to perform complexation and passivation functions. The 45-60 minute holding time is sufficient to allow the grafting and complexation reactions to reach equilibrium, ensuring batch-to-batch stability of the modification effect. Slowly cooling to 40-60℃ before discharging prevents tempering and oxidation of the high-temperature carbon black upon contact with air, and also avoids stress within the particles caused by rapid cooling.

[0043] A modified pyrolysis carbon black prepared according to the above preparation method.

[0044] An application of the above-mentioned modified pyrolysis carbon black is its use in rubber sidewall rubber, the preparation process of which is as follows: After plasticizing styrene-butadiene rubber, antioxidants, activators, and plasticizers are added for a first-stage mixing process. During the first-stage mixing, the rotation speed is 45-55 rpm and the mixing time is 120-180 s. After the first-stage mixing, the rubber is discharged at 130-140℃ to obtain the first-stage compound. The modified pyrolysis carbon black is coated on the surface of the first-stage compound and allowed to stand for 4-20 hours. Then, vulcanizing agents and accelerators are added for a second-stage mixing process. During the second-stage mixing, the rotation speed is 30-40 rpm and the mixing time is 180-240 s. The rubber is discharged at 90-100℃. After the rubber is discharged, it is cooled to room temperature to obtain the second-stage compound, which is then vulcanized to obtain the rubber sidewall rubber.

[0045] The antioxidant includes at least one of p-phenylenediamine antioxidants and ketamine antioxidants, wherein the p-phenylenediamine antioxidant includes at least one of antioxidant 4020, antioxidant 4010NA, and antioxidant 3100; and the ketamine antioxidant is antioxidant RD.

[0046] The activator is a combination of zinc oxide and stearic acid.

[0047] The plasticizer includes at least one of aromatic oil, naphthenic oil, environmentally friendly aromatic oil (TDAE), residual aromatic extract oil (RAE), and liquid polybutadiene.

[0048] The vulcanizing agent is sulfur, preferably insoluble sulfur.

[0049] The accelerator includes at least one of sulfenamide accelerators, thiazole accelerators, and thiuram accelerators. The sulfenamide accelerator includes at least one of accelerator NS, accelerator CZ, and accelerator DZ; the thiazole accelerator includes accelerator M and accelerator DM; and the thiuram compound includes at least one of TMTD or DPTT.

[0050] By leveraging the unique thermodynamic affinity between the diketone organic coating layer on the surface of modified carbon black and the rubber matrix, pre-wetting and diffusion of carbon black are achieved during the room temperature settling stage. This process offers three key benefits: First, it completely avoids the strong shearing action of high-temperature primary mixing, fully protecting the interfacial active structure of the diketone modified layer; second, the filler-rubber interface formed by low-temperature diffusion has lower pre-stress, which is beneficial for stress dissipation under dynamic flexural stress, further improving flexural crack life; and third, the absence of carbon black in the primary mixing stage significantly reduces mixing energy consumption and discharge temperature, aligning with green manufacturing trends.

[0051] Example 1 Preparation of the modified solution: Weigh 8 parts by weight of camphorquinone (alicyclic α-diketone, purchased from Aladdin Reagent, purity 97%) and 3 parts by weight of 1,3-indanedione (fused-ring aromatic β-diketone, purchased from Bid Pharmaceutical, purity 98%), and set aside. Weigh 15 parts of naphthenic oil and add it to a jacketed reactor with a stirrer, and heat to 60°C. Slowly add 1,3-indanedione while stirring, continuing to stir until completely dissolved to obtain a β-diketone solution. Then cool the solution to 40°C, add camphorquinone under light-protected conditions, and stir until uniformly dispersed to obtain the modified solution.

[0052] Pretreatment of pyrolysis carbon black: Take 100 parts of pyrolysis carbon black (ash content approximately 15%, iodine absorption value 68 g / kg, DBP absorption value 72 cm⁻¹) 3 (100g) was first placed in a 1 mol / L sodium hydroxide aqueous solution and stirred and impregnated at 80℃ for 2 hours for alkaline pore-forming treatment. After filtration, it was washed with deionized water until the filtrate was neutral, then washed once with 0.5 mol / L dilute hydrochloric acid solution, and finally washed with deionized water until neutral. It was then dried in a 110℃ forced-air drying oven to constant weight to obtain pretreated pyrolysis carbon black.

[0053] Preparation of modified pyrolysis carbon black: The pretreated pyrolysis carbon black was fed into a high-speed mixer and preheated to 110°C at 900 rpm. The modification liquid was sprayed evenly onto the surface of the stirring pyrolysis carbon black through an atomizing nozzle for 12 minutes. After spraying, high-speed mixing continued at 110°C for 20 minutes to allow the modification liquid to fully penetrate and adsorb. The mixture was transferred to a nitrogen-protected reactor and heated to 130°C under nitrogen atmosphere, and kept at this temperature with stirring for 50 minutes for heat treatment. After the heat treatment, the mixture was cooled to 50°C under nitrogen protection with stirring, discharged, and passed through a 60-mesh sieve to obtain the modified pyrolysis carbon black.

[0054] Example 2 Compared to Example 1, the modified liquid in this example is prepared by simple mixing, and everything else is the same as in Example 1.

[0055] The modified solution is prepared by weighing 8 parts by weight of camphorquinone, 3 parts by weight of 1,3-indanedione, and 15 parts by weight of naphthenic oil and adding them to a jacketed reactor equipped with a stirrer, then heating to 50°C. The mixture is stirred until uniformly dispersed to obtain the modified solution.

[0056] Example 3 Compared to Example 1, the modified liquid in this example is simply mixed with carbon black, and everything else is the same as in Example 1.

[0057] Specifically, the modified liquid is poured into the pyrolysis carbon black being stirred, and the mixture is continued to be mixed at high speed at 110°C for 20 minutes to allow the modified liquid to fully penetrate and adsorb.

[0058] Example 4 Compared with Example 1, this example changes the types and proportions of α-diketone and β-diketone, while everything else remains the same as in Example 1. Specifically, 5 parts by weight of 1,2-cyclohexanedione and 2 parts by weight of 1,3-indanedione are weighed and set aside.

[0059] Example 5 Compared with Example 1, this example changes the types and proportions of α-diketone and β-diketone, while everything else remains the same as in Example 1. Specifically, 10 parts by weight of camphorquinone and 5 parts by weight of 2-methyl-1,3-indanedione are weighed and set aside.

[0060] Example 6 Compared with Example 1, this example changes the process parameters for the preparation of modified pyrolytic carbon black mixing process and heat treatment, while all other aspects are the same as in Example 1.

[0061] Specifically, the pretreated pyrolysis carbon black is fed into a high-speed mixer and preheated to 110°C at 900 rpm. The modified liquid is then uniformly sprayed onto the surface of the stirring pyrolysis carbon black through an atomizing nozzle for 15 minutes. After spraying, high-speed mixing continues at 110°C for 20 minutes to allow the modified liquid to fully penetrate and adsorb. The mixture is then transferred to a nitrogen-protected reactor and heated to 120°C under nitrogen atmosphere, and maintained at this temperature with stirring for 60 minutes for heat treatment. After heat treatment, the mixture is cooled to 40°C under nitrogen protection with stirring, discharged, and passed through a 60-mesh sieve to obtain the modified pyrolysis carbon black.

[0062] Example 7 Compared with Example 1, this example changes the process parameters for the preparation of modified pyrolytic carbon black mixing process and heat treatment, while all other aspects are the same as in Example 1.

[0063] Specifically, the pretreated pyrolysis carbon black is fed into a high-speed mixer and preheated to 110°C at 900 rpm. The modified liquid is then uniformly sprayed onto the surface of the stirring pyrolysis carbon black through an atomizing nozzle for 10 minutes. After spraying, high-speed mixing continues at 110°C for 20 minutes to allow the modified liquid to fully penetrate and adsorb. The mixture is then transferred to a nitrogen-protected reactor and heated to 140°C under nitrogen atmosphere, and held at this temperature with stirring for 45 minutes for heat treatment. After the heat treatment, the mixture is cooled to 60°C under nitrogen protection with stirring, discharged, and passed through a 60-mesh sieve to obtain the modified pyrolysis carbon black.

[0064] Comparative Example 1 Compared with Example 1, the modified liquid of this comparative example does not contain α-diketone, but is otherwise the same as that of Example 1.

[0065] Comparative Example 2 Compared with Example 1, the modified liquid of this comparative example does not contain β-diketone, but is otherwise the same as that of Example 1.

[0066] Comparative Example 3 Compared with Example 1, the modified liquid in this comparative example is not subjected to heat treatment, but otherwise it is the same as Example 1.

[0067] Comparative Example 4 Compared with Example 1, this comparative example has 5 parts α-diketone and 15 parts β-diketone added to the modified solution by mass, and all other aspects are the same as in Example 1.

[0068] Comparative Example 5 Compared with Example 1, this comparative example uses carbon black N330 instead of modified pyrolysis carbon black.

[0069] The modified pyrolysis carbon black obtained in Examples 1-7 and Comparative Examples 1-5 were applied to the preparation of rubber sidewall rubber. Specific experimental examples are as follows.

[0070] Experimental Example 1 Styrene-butadiene rubber (SBR) was plasticized in an internal mixer for 40 seconds, followed by the addition of antioxidants, activators, and plasticizers. The internal mixer rotor speed was set to 50 rpm, and the mixing time was 150 seconds, with the discharge temperature controlled at 135°C. After discharge, the rubber was passed through a two-roll mill three times, and the sheet was cooled to room temperature to obtain a first-stage compound.

[0071] A section of the rubber compound was left to stand at room temperature for 12 hours. During this time, 45 parts of modified pyrolysis carbon black prepared in Example 1 were coated onto the surface of the rubber compound, so that the surface of the rubber compound was completely covered with carbon black powder to form a composite, and the compound was left to stand.

[0072] The composite material, after being left to stand and soak, was fed into an internal mixer at a rotor speed of 35 rpm for 210 seconds to ensure the carbon black was fully incorporated and evenly dispersed into the rubber compound. Then, the vulcanizing agent and accelerator were added, and mixing continued until homogeneous. The discharge temperature was controlled at 95℃. After discharge, the compound was passed through a two-roll mill and rolled into triangular sheets five times. The sheets were then cooled to obtain the two-stage compound.

[0073] The two-stage compound rubber was placed into a mold of a flat vulcanizing machine and vulcanized at 150°C and 10 MPa for 20 minutes. After cooling, the rubber sidewall rubber sample was obtained.

[0074] The formulation of the rubber sidewall rubber in this embodiment is shown in Table 1 below.

[0075] Table 1 Rubber Sidewall Compound Experimental Example 2 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared in Example 2, and all other aspects are the same as in Experimental Example 1.

[0076] Experimental Example 3 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared in Example 3, and all other aspects are the same as Experimental Example 1.

[0077] Experimental Example 4 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared in Example 4, and all other aspects are the same as in Experimental Example 1.

[0078] Experimental Example 5 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared in Example 5, and all other aspects are the same as Experimental Example 1.

[0079] Experimental Example 6 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared in Example 6, and all other aspects are the same as Experimental Example 1.

[0080] Experimental Example 7 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared in Example 7, and all other aspects are the same as Experimental Example 1.

[0081] Comparative Example 1 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared by Comparative Example 1, and all other aspects are the same as Experimental Example 1.

[0082] Comparative Example 2 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared by Comparative Example 2, and all other aspects are the same as Experimental Example 1.

[0083] Comparative Example 3 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared by Comparative Example 3, and all other aspects are the same as Experimental Example 1.

[0084] Comparative Example 4 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared by Comparative Example 4, and all other aspects are the same as Experimental Example 1.

[0085] Comparative Example 5 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared by Comparative Example 5, and all other aspects are the same as Experimental Example 1.

[0086] Comparative Example 6 Compared with Experimental Example 1, this experimental example uses the modified pyrolysis carbon black prepared in Comparative Example 1, but the timing of its addition has been changed; otherwise, it is the same as Experimental Example 1.

[0087] Specifically, styrene-butadiene rubber was plasticized in an internal mixer for 40 seconds, followed by the addition of 45 parts of modified pyrolytic carbon black, antioxidant, activator, and plasticizer prepared in Example 1. The internal mixer rotor speed was set to 50 rpm, and the mixing time was 150 seconds, with the discharge temperature controlled at 135°C. After discharge, the rubber was passed through a two-roll mill three times, and the sheet was cooled to room temperature to obtain a first-stage compound.

[0088] The first stage of compound was fed into an internal mixer, with the rotor speed set to 35 rpm, and mixed for 210 seconds to ensure that the carbon black was fully incorporated into the compound and evenly dispersed. Then, the vulcanizing agent and accelerator were added, and mixing continued until homogeneous. The discharge temperature was controlled at 95℃. After discharge, the compound was passed through a two-roll mill and rolled into triangular sheets five times. The sheets were then cooled to obtain the second stage of compound.

[0089] The two-stage compound rubber was placed into a mold of a flat vulcanizing machine and vulcanized at 150°C and 10 MPa for 20 minutes. After cooling, the rubber sidewall rubber sample was obtained.

[0090] The rubber sidewall samples obtained from Experimental Examples 1-7 and Comparative Examples 1-6 were tested in accordance with the standards shown below, and the test results are shown in Tables 2-3 below.

[0091] Tensile strength, stress at 300% constant elongation, elongation at break: GB / T 528-2009; Tear strength: GB / T 529-2008 Shore hardness: GB / T 39693.4-2025; Tensile property retention rate after hot air aging: GB / T 3512-2014; Flexural crack life: GB / T 13934-2006; Carbon black dispersion grade: GB / T 6030-2006; Odor rating of rubber compound: Sensory evaluation method (refer to VDA 270 odor test method).

[0092] Table 2 Test results of rubber sidewall samples from Experimental Examples 1-7 Table 3 Test results of rubber sidewall samples from comparative examples 1-6 Example 1 employed the optimal scheme of this invention, namely, stepwise temperature-controlled preparation of the modified liquid, atomized spray mixing, and anaerobic heat treatment. The resulting sidewall rubber tensile strength recovered to 98.1% of the original N330, and the aging retention rate and odor level both surpassed those of the original N330. Example 2 changed the modified liquid preparation method to simple mixing. The performance was slightly lower than that of Example 1, but still significantly better than the single diketone modification scheme, indicating that stepwise temperature-controlled preparation is beneficial for protecting the activity of α-diketone. Example 3 changed atomized spraying to direct pouring and mixing. The performance was slightly lower than that of Example 1, but still better than the comparative examples, indicating that atomized spraying is crucial for coating uniformity and performance stability. Examples 4-7 changed the raw materials and preparation process of the modified liquid, and similar excellent performance was obtained, proving that the modifier combination and process range of this invention have wide applicability.

[0093] Comparative Example 1, using only β-diketone, showed a tensile strength of only 17.7 MPa and an aging retention rate of 68%, indicating severely insufficient reinforcement. Comparative Example 2, using only α-diketone, saw its aging retention rate plummet to 53% and its odor level deteriorate to level 4, failing to suppress metal catalytic aging and odor volatilization. Comparative Example 3, without heat treatment, showed a tensile strength of only 17.6 MPa, demonstrating that anaerobic heat treatment is a necessary condition for α-diketone grafting. Comparative Example 4 (α:β = 5:15 imbalanced ratio) suffered from deteriorated tensile stress and odor due to excessive β-diketone interfering with vulcanization. Comparative Example 5, using carbon black N330, achieved the best reinforcement, but its aging retention rate of 72% was surpassed by the 78% of Example 1. Comparative Example 6, using a conventional feeding process, showed an aging retention rate of only 55%, strongly demonstrating that a high-temperature, high-shear process can destroy the diketone modified layer, highlighting the irreplaceable nature of the storage coating and two-stage mixing application process of this application.

[0094] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing modified pyrolysis carbon black, characterized in that, The preparation method includes mixing the modified liquid with thermally decomposed carbon black, and then heat-treating the mixture in an oxygen-free environment to obtain modified thermally decomposed carbon black. The modified liquid is prepared by dissolving α-diketone and β-diketone in a solvent. The mass ratio of the α-diketone to the β-diketone is 5-12:2-6.

2. The method for preparing modified pyrolysis carbon black according to claim 1, characterized in that, The total amount of α-diketone and β-diketone used is 5-15% of the mass of thermally decomposed carbon black.

3. The method for preparing modified pyrolysis carbon black according to claim 1, characterized in that, The α-diketone is an alicyclic α-diketone; the β-diketone is a fused-ring aromatic β-diketone.

4. The method for preparing modified pyrolysis carbon black according to claim 3, characterized in that, The α-diketone includes at least one of camphorquinone or 1,2-cyclohexanedione; the β-diketone includes at least one of 1,3-indanedione, 2-methyl-1,3-indanedione, or benzo[1,3]dioxacyclopenten-5-yl-β-diketone.

5. The method for preparing modified pyrolysis carbon black according to claim 1, characterized in that, The preparation method of the modified liquid includes: heating the solvent to 40-70°C, adding β-diketone under stirring to obtain a β-diketone solution, cooling the β-diketone solution to 30-50°C, and then adding α-diketone under light-protected conditions to obtain the modified liquid; The solvent is at least one of naphthenic oil, liquid polybutadiene, aromatic oil, and environmentally friendly rubber filler oil.

6. The method for preparing modified pyrolysis carbon black according to claim 1, characterized in that, The mixing process involves spraying the modified liquid onto the surface of the pyrolytic carbon black in an atomized form for 10-15 minutes.

7. The method for preparing modified pyrolysis carbon black according to claim 1, characterized in that, The heat treatment process involves heating to 120-140℃, holding and stirring for 45-60 minutes, and then cooling to 40-60℃ after stirring.

8. A modified pyrolysis carbon black prepared by the preparation method according to any one of claims 1-7.

9. An application of the modified pyrolysis carbon black according to claim 8, characterized in that, Its application in rubber sidewall rubber, the preparation process of which is as follows: After plasticizing styrene-butadiene rubber, antioxidants, activators and plasticizers are added for a first-stage mixing. After the first-stage mixing, the rubber is discharged to obtain a first-stage compound. The modified pyrolysis carbon black is coated on the surface of the first-stage compound and left to stand. Then, vulcanizing agents and accelerators are added for a second-stage mixing. After the second-stage mixing, the rubber is discharged to obtain a second-stage compound, which is then vulcanized to obtain the rubber sidewall rubber.

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