Preparation method of modified coal pitch and preparation method of carbon material

Abstract

The application discloses a preparation method of modified coal pitch and a preparation method of carbon material. The preparation method of modified coal pitch comprises the following steps: mixing a plasticizing agent, a synergist and an additive, then adding coal pitch, stirring, heating to 140-160 DEG C, and constant temperature reaction, so that the modified coal pitch is obtained; the plasticizing agent comprises dibutyl phthalate and / or dioctyl phthalate; the synergist comprises one or more of light oil, naphthalene oil, wash oil, phenol oil and anthracene oil; and the additive comprises carboxymethyl cellulose and / or sodium polyacrylate. The application can significantly improve the wettability of the binder coal pitch to the aggregate without reducing the coking value of the coal pitch, makes the modified coal pitch more evenly distributed among the aggregate, and makes the obtained carbon graphite material have lower porosity, higher bulk density and more excellent electrical and mechanical properties, and the carbon graphite material has excellent thermal stability and structural integrity under high-temperature working conditions.

Description

Technical Field

[0001] This invention belongs to the field of carbon graphite materials, and particularly relates to a method for preparing a binder and a method for preparing carbon materials. Background Technology

[0002] Medium-coarse structure graphite materials possess excellent thermal shock resistance, oxidation resistance, high-temperature resistance, and chemical corrosion resistance, enabling them to adapt to various harsh high-temperature environments. In addition to advantages such as aggregate particle size matching, strong interphase interactions, and homogeneity, medium-coarse structure graphite materials also offer advantages such as low cost and short production cycle, making them widely used in casting, chemical, electronics, photovoltaic, high-temperature treatment, non-ferrous metals, ceramics, and refractory materials. The interaction between aggregates and binders during the kneading process has a significant impact on medium-coarse structure graphite materials. Ideally, the kneading process involves molten coal tar pitch first coating the porous surface of calcined coke, then slowly wetting and penetrating into the pores of the calcined coke through capillary action, ultimately filling the gaps between coke particles. However, in practice, due to surface tension, it is difficult for coal tar pitch to penetrate into the capillaries of the calcined coke, making it difficult for the calcined coke to be uniformly coated by the molten coal tar pitch. This significantly affects the homogeneity and batch stability of medium-coarse structure graphite materials.

[0003] The wetting and penetration of coal tar pitch onto the surface of calcined coke depends on factors such as coke particle size, surface energy, and porosity. Simultaneously, the softening point, chemical composition, surface tension, and viscosity of the coal tar pitch also significantly influence its interaction. A suitable viscosity facilitates the full penetration and filling of the pores in the calcined coke by the coal tar pitch, forming a uniform coating layer and improving the structural density and mechanical stability of the composite material. Current technologies typically improve the fluidity of coal tar pitch by adding light components such as anthracene oil; however, these components are prone to volatilization at high temperatures, leading to a decrease in coking value and consequently, an increase in the porosity and a decrease in the mechanical properties of the final carbon material, making it unsuitable for high-temperature environments. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for preparing modified coal tar pitch and a method for preparing carbon materials that can improve the wetting ability of coal tar pitch to aggregates and improve the thermal stability of carbon materials without reducing the coking value of coal tar pitch.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] A method for preparing modified coal tar pitch includes the following steps: mixing plasticizer, synergist and additive, then adding coal tar pitch, stirring, heating to 140-160℃, and reacting at a constant temperature to obtain the modified coal tar pitch.

[0007] The plasticizer includes dibutyl phthalate and / or dioctyl phthalate; the synergist includes one or more of light oil, naphthalene oil, wash oil, phenolic oil and anthracene oil; the additive includes carboxymethyl cellulose and / or sodium polyacrylate.

[0008] In the above preparation method, preferably, the mass ratio of the plasticizer to coal tar pitch is (1-3):100.

[0009] In the above preparation method, preferably, the mass ratio of the synergist to coal tar pitch is (2-6):100.

[0010] In the above preparation method, preferably, the mass ratio of the plasticizer, the additive and the synergist is (1-2):(1-2):2.

[0011] In this invention, the dosage control of plasticizers, synergists, and additives has a significant impact on the flowability, uniformity, and thermal stability of the modified coal tar pitch system and the resulting carbon material. Excessive use of plasticizers and synergists can lead to a decrease in the cross-linking density between coal tar pitch molecules, weakening the structural compactness and mechanical strength of the carbon material. Under high-temperature conditions such as electrolytic aluminum anodes, this may cause accelerated anode wear or structural cracking. Insufficient dosage makes it difficult to effectively reduce the viscosity of the coal tar pitch, resulting in uneven distribution and poor flowability of the modified coal tar pitch in the mixture, leading to uneven structure during molding and affecting the thermal stability of the carbon material. There is a clear synergistic relationship between plasticizers and synergists. Synergists can improve the wettability and compatibility of the system, promoting the full penetration and uniform distribution of plasticizers in the coal tar pitch system. However, when the proportion of synergists is too low, the flow improvement effect is limited; when the proportion is too high, it will reduce the coking value of the coal tar pitch, weakening the high-temperature structural stability of the carbon material. Building upon this foundation, the present invention further introduces carboxymethyl cellulose and / or sodium polyacrylate as synergistic additives. Unlike existing technologies that only add additives to improve asphalt performance, the additives in this invention significantly promote the uniform diffusion and interfacial spreading of plasticizers and synergists in the system, thereby enhancing their flow regulation and wetting synergistic effects. When the additive dosage is too low, it is difficult to form an effective stable structure, resulting in the plasticizers and synergists being unable to fully exert their regulatory effects; when the additive dosage is too high, it will increase the viscosity of the system or introduce too many polar groups, affecting the carbonization process of the asphalt and potentially leading to a decrease in coking value. Therefore, by rationally controlling the amount of additives added, so that they can provide effective dispersion stability without affecting the carbonization characteristics of the system, the synergistic optimization of plasticizers, synergists, and additives can be achieved. Under the synergistic effect of the three, modified coal tar pitch can achieve excellent dispersion uniformity and penetration ability at a relatively low amount of modified substances added, significantly improving the coating and wetting effect of coal tar pitch between aggregates, resulting in carbon materials with higher mechanical strength, lower porosity, and better high-temperature thermal stability.

[0012] In the above preparation method, preferably, when mixing the plasticizer, synergist, and additive, the three are mixed first, stirring is started, and the oil bath temperature is raised to 100-110℃. First, the plasticizer, synergist, and additive are stirred and mixed evenly, which is beneficial for each substance to exert its effect and for their synergistic effect.

[0013] In the above preparation method, preferably, the reaction time is controlled to be 1-3 hours during the isothermal reaction. When mixing the plasticizer, synergist, additives, and coal tar pitch, it is necessary to reasonably control the reaction temperature and reaction time, ideally between 140-160℃ and 1-3 hours. If the temperature is below this range, the plasticizer will fail to react with the coal tar pitch, resulting in limited effectiveness. If the temperature is above this range, it may lead to over-reaction, such as excessive cross-linking, thermal degradation, or chemical decomposition, which will reduce the performance of the coal tar pitch and the prepared carbon material.

[0014] As a general technical concept, the present invention also provides a method for preparing carbon material, comprising the following steps: mixing calcined coke aggregate and modified coal tar pitch, kneading the mixture, statically pressing the kneaded paste into shape, and then calcining it to obtain the carbon material; wherein the modified coal tar pitch is the modified coal tar pitch prepared by the above preparation method.

[0015] In the above preparation method, preferably, the mass of the modified coal tar pitch is 15%-17% of the mass of the calcined coke aggregate.

[0016] In the above preparation method, preferably, the kneading temperature is 160-170℃ and the kneading time is 20-30min.

[0017] In this invention, the aggregate may be one or more of calcined petroleum coke, calcined pitch coke, and calcined needle coke, and the coal pitch may be one or more of modified coal pitch, medium-temperature coal pitch, and high-temperature pitch.

[0018] This invention primarily addresses the problem of poor wettability of coal tar pitch (a binder) to carbonaceous aggregates in medium-coarse structure graphite materials. It improves the thermal stability of the carbon material by enhancing the uniformity of coal tar pitch distribution, while ensuring that the coking value of the coal tar pitch is not reduced, thus avoiding excessive porosity in the carbon material and affecting product performance. The principle of this invention lies in introducing light oils, ester compounds, and synergistic additives into the coal tar pitch to alter the interfacial interaction behavior between the calcined coke and the coal tar pitch, enhancing the wetting and penetration ability of the coal tar pitch on the coke surface and pores, resulting in a more uniform distribution of the coal tar pitch among the aggregates. The medium-coarse structure graphite material prepared in this way possesses comprehensive performance advantages such as strong interfacial forces, reasonable particle size distribution, high residual carbon value, uniform and dense structure, and excellent thermal stability.

[0019] In existing technologies, esters or anthracene oils are typically added to coal tar pitch to reduce its viscosity, thereby improving its permeability during molding and making it easier to penetrate the gaps between carbonaceous aggregates. However, the use of these substances alone significantly reduces the coking value of the coal tar pitch, generating more pores during calcination, leading to decreased structural density and weakened mechanical strength of the carbon material. Furthermore, since esters and anthracene oils only adjust the system's fluidity and cannot simultaneously ensure the uniform dispersion of different components in a multiphase system, uneven wetting and insufficient spreading still exist at the interface between the coal tar pitch and the calcined coke. As a result, the distribution of coal tar pitch on the aggregate surface and in the pores is uneven, with some areas exhibiting good thermal stability while others are poorly bonded, leading to poor overall thermal stability of the carbon material.

[0020] This invention achieves synergistic regulation of the rheological properties and interfacial wetting behavior of coal tar pitch by incorporating a composite system of ester compounds and light oils, further combined with additives, through the multi-component synergistic effect. Plasticizers such as dibutyl phthalate or dioctyl phthalate can insert into the molecular chains of coal tar pitch, weakening intermolecular forces, reducing system viscosity, and improving flexibility, thereby improving the flowability and molding performance of coal tar pitch. Light oil components (such as light oil, naphthalene oil, wash oil, phenolic oil, anthracene oil, etc.) have good solubility and low viscosity characteristics, effectively dissolving polycyclic aromatic hydrocarbons and high molecular weight components in coal tar pitch, promoting the uniform distribution of plasticizers in the system, and further improving the dispersibility and structural uniformity of coal tar pitch. The highly aromatic structure of anthracene oil can also enhance the antioxidant properties of coal tar pitch and reduce thermal degradation at high temperatures, which is particularly important for high-temperature applications such as prebaked anodes for electrolytic aluminum. To further improve the uniformity and thermal stability of the system, this invention also introduces carboxymethyl cellulose or sodium polyacrylate as synergistic additives to improve interfacial wettability, strengthen intermolecular forces, and enhance the wetting and penetration ability of coal tar pitch on the surface of calcined coke, enabling coal tar pitch to smoothly and uniformly penetrate into the micropores of aggregates, achieving dense coating and orderly bonding. The mechanism of action of the additives is as follows: This invention is a multi-component organic melt system formed under high temperature conditions of 140-160℃. In this system, dibutyl phthalate / dioctyl phthalate, light oil, wash oil, naphthalene oil, phenolic oil, anthracene oil, etc., work together to cause significant molecular swelling and polarity enhancement of coal tar pitch, thereby forming an organic swelling environment with certain compatibility with polymer additives. In this organic melt system, carboxymethyl cellulose or sodium polyacrylate mainly participates in system stability through the following mechanisms: 1. Interfacial anchoring effect of polar groups: polar groups such as carboxyl and hydroxyl groups can interact with aromatic components, heteroatomic groups and light atoms in coal tar pitch. 1. The formation of polar adsorption and hydrogen bonding between light oil molecules enhances the interfacial anchoring ability of additives in the asphalt phase; 2. High-temperature swelling-steric hindrance effect: In the swollen organic environment constructed by plasticizer and light oil, the polymer chains undergo a certain degree of compliant unfolding, forming a molecular-scale steric hindrance shielding layer in the asphalt phase, inhibiting the aggregation of asphalt molecules; 3. Synergistic dispersion and interfacial stabilization effect: The additive does not disperse coal tar pitch alone, but rather stabilizes the "plasticizer-light oil-asphalt" composite phase structure by promoting the uniform diffusion of plasticizer and synergist in coal tar pitch, thereby improving the spreading uniformity of coal tar pitch on the aggregate surface and in micropores.

[0021] Overall, the plasticizer, synergist and additives used in this invention have a significant synergistic effect. After reasonable proportioning and control, the softening point can be effectively reduced without lowering the coking value of coal tar pitch, the carbonization yield can be increased, the overall structural density of the material can be significantly improved, and the resulting carbon material can have higher mechanical strength and thermal stability.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] The modified coal tar preparation method of this invention can significantly improve the wettability of the binder coal tar to aggregates without reducing the coking value of the coal tar, optimize the interfacial interaction between coke and coal tar, and make the modified coal tar more uniformly distributed among the aggregates. By enhancing the penetration ability of the binder, the proportion of coal tar entering the micropores of the aggregate can be effectively increased, reducing the number of original "innate pores" in the aggregate; at the same time, the fluidity of the coal tar is improved, reducing the formation of "acquired pores" caused by local agglomeration. This method significantly enhances the wetting and coating effect of coal tar on the coke surface, resulting in carbon-graphite materials with lower porosity, higher bulk density, and better electrical and mechanical properties, and exhibiting excellent thermal stability and structural integrity under high-temperature conditions, thereby obtaining high-quality medium-coarse structure carbon-graphite products. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 The results show the wettability test results of different coal tar pitches on calcined coke in Examples 1-4 and Comparative Examples 1-5.

[0026] Figure 2 SEM images of the carbon materials obtained in Examples 1-4 and Comparative Examples 1-5 (a, b, c, d, e, f, g, h, i in the figures correspond to Examples 1, 2, 3, 4, Comparative Examples 1, 2, 3, 4, 4, and 5, respectively). Detailed Implementation

[0027] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0028] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0029] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0030] Example 1:

[0031] A method for preparing modified coal tar pitch includes the following steps: Weigh 1g of dibutyl phthalate, 2g of wash oil, and 1g of carboxymethyl cellulose into a 500mL three-necked flask. Start stirring, heat in an oil bath to 104℃, then add 50g of coal tar pitch and stir at a constant temperature for 40min. Heat to 150℃ and hold at that temperature for 2h. Finally, allow to cool naturally to room temperature and remove the flask to obtain modified coal tar pitch.

[0032] A method for preparing a carbon material includes the following steps:

[0033] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0034] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0035] Step 3: Prepare modified coal tar using the above-mentioned method for preparing modified coal tar.

[0036] Step 4: Prepare a small sample of medium-coarse structure graphite material using modified coal tar pitch. The conventional medium-coarse structure graphite material formula is adopted, and the preparation process is as follows: Calcinated coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder (the product obtained by drying in step 2, the same below) content 26%, modified coal tar pitch accounts for 15.5% of the mass of calcined coke, the kneading temperature is 165℃, the kneading time is 25min, and the kneaded paste is transferred into a mold for static pressing to obtain a green medium-coarse structure graphite material.

[0037] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0038] Example 2:

[0039] A method for preparing modified coal tar pitch includes the following steps: Weigh 1g of dioctyl phthalate, 2g of wash oil, and 1g of carboxymethyl cellulose into a 500mL three-necked flask. Start stirring, heat in an oil bath to 104℃, then add 50g of coal tar pitch and stir at a constant temperature for 40min. Heat to 150℃ and hold at that temperature for 2h. Finally, allow to cool naturally to room temperature and remove the flask to obtain modified coal tar pitch.

[0040] A method for preparing a carbon material includes the following steps:

[0041] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0042] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0043] Step 3: Prepare modified coal tar using the above-mentioned method for preparing modified coal tar.

[0044] Step 4: Prepare medium-coarse structure graphite material samples using modified coal tar pitch. The conventional medium-coarse structure graphite material formulation is adopted, and the preparation process is as follows: calcined coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder content 26%, modified coal tar pitch accounts for 15.5% of the mass of calcined coke, the kneading temperature is 165℃, the kneading time is 25min, and the kneaded paste is transferred into a mold for static pressing to obtain medium-coarse structure graphite material green body.

[0045] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0046] Example 3:

[0047] A method for preparing modified coal tar pitch includes the following steps: Weigh 1g of dibutyl phthalate, 2g of naphthalene oil, and 1g of carboxymethyl cellulose into a 500mL three-necked flask. Start stirring, heat in an oil bath to 104℃, then add 50g of coal tar pitch and stir at a constant temperature for 40min. Heat to 140℃ and hold at that temperature for 1h. Finally, allow to cool naturally to room temperature and remove the flask to obtain modified coal tar pitch.

[0048] A method for preparing a carbon material includes the following steps:

[0049] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0050] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0051] Step 3: Prepare modified coal tar using the above-mentioned method for preparing modified coal tar.

[0052] Step 4: Prepare medium-coarse structure graphite material samples using modified coal tar pitch. The conventional medium-coarse structure graphite material formulation is adopted, and the preparation process is as follows: calcined coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder content 26%, modified coal tar pitch accounts for 15.5% of the mass of calcined coke, the kneading temperature is 165℃, the kneading time is 25min, and the kneaded paste is transferred into a mold for static pressing to obtain medium-coarse structure graphite material green body.

[0053] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0054] Example 4:

[0055] A method for preparing modified coal tar pitch includes the following steps: Weigh 1g of dibutyl phthalate, 2g of wash oil, and 1g of sodium polyacrylate into a 500mL three-necked flask. Start stirring, heat in an oil bath to 104℃, add 50g of coal tar pitch, and stir at a constant temperature for 40min. Heat to 160℃, maintain the temperature for 3h, and finally cool naturally to room temperature to obtain modified coal tar pitch.

[0056] A method for preparing a carbon material includes the following steps:

[0057] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0058] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0059] Step 3: Prepare modified coal tar using the above-mentioned method for preparing modified coal tar.

[0060] Step 4: Prepare medium-coarse structure graphite material samples using modified coal tar pitch. The conventional medium-coarse structure graphite material formulation is adopted, and the preparation process is as follows: calcined coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder content 26%, modified coal tar pitch accounts for 15.5% of the mass of calcined coke, the kneading temperature is 165℃, the kneading time is 25min, and the kneaded paste is transferred into a mold for static pressing to obtain medium-coarse structure graphite material green body.

[0061] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0062] Comparative Example 1:

[0063] A method for preparing a carbon material includes the following steps:

[0064] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0065] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0066] Step 3: Weigh 1g of dibutyl phthalate and pour it into a 500mL three-necked flask. Start stirring, heat in an oil bath to 130℃, then add 50g of coal tar pitch and stir at a constant temperature for 40min. Heat to 150℃ and hold at that temperature for 2h. Finally, allow it to cool naturally to room temperature and remove it to obtain modified coal tar pitch.

[0067] Step 4: Prepare medium-coarse structure graphite material samples using modified coal tar pitch. The conventional medium-coarse structure graphite material formulation is adopted, and the preparation process is as follows: calcined coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder content 26%, modified coal tar pitch accounting for 15.5% of the mass of calcined coke, kneading temperature 165℃, kneading time 25min, after kneading the paste is transferred into a mold and statically pressed to obtain medium-coarse structure graphite material green body.

[0068] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0069] Comparative Example 2:

[0070] A method for preparing a carbon material includes the following steps:

[0071] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0072] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0073] Step 3: Weigh 3g of washing oil and pour it into a 500mL three-necked flask. Turn on the stirrer, heat the oil bath to 104℃, add 50g of coal tar pitch, and stir at a constant temperature for 40min. Heat to 150℃ and hold at that temperature for 2h. Finally, let it cool naturally to room temperature and remove it to obtain modified coal tar pitch.

[0074] Step 4: Prepare medium-coarse structure graphite material samples using modified coal tar pitch. The conventional medium-coarse structure graphite material formulation is adopted, and the preparation process is as follows: calcined coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder content 26%, modified coal tar pitch accounting for 15.5% of the mass of calcined coke, kneading temperature 165℃, kneading time 25min, after kneading the paste is transferred into a mold and statically pressed to obtain medium-coarse structure graphite material green body.

[0075] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0076] Comparative Example 3:

[0077] A method for preparing a carbon material includes the following steps:

[0078] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0079] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0080] Step 3: Weigh 1g of dibutyl phthalate and 1g of carboxymethyl cellulose into a 500mL three-necked flask. Start stirring, heat in an oil bath to 104℃, then add 50g of coal tar pitch and stir at a constant temperature for 40min. Heat to 150℃ and hold at that temperature for 2h. Finally, allow to cool naturally to room temperature and remove the flask to obtain modified coal tar pitch.

[0081] Step 4: Prepare medium-coarse structure graphite material samples using coal tar pitch. The conventional medium-coarse structure graphite material formulation is adopted, and the preparation process is as follows: calcined coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder content 26%, modified coal tar pitch accounting for 15.5% of the mass of calcined coke, kneading temperature 165℃, kneading time 25min, after kneading the paste is transferred into a mold and statically pressed to obtain medium-coarse structure graphite material green body.

[0082] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0083] Comparative Example 4:

[0084] A method for preparing a carbon material includes the following steps:

[0085] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0086] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0087] Step 3: Weigh 1g of dibutyl phthalate, 2g of wash oil, and 1g of carboxymethyl cellulose into a 500mL three-necked flask. Start stirring, heat in an oil bath to 90℃, then add 50g of coal tar pitch and stir at a constant temperature for 40min. Increase the temperature to 180℃ and hold for 2h. Finally, allow to cool naturally to room temperature and remove the flask to obtain modified coal tar pitch.

[0088] Step 4: Prepare medium-coarse structure graphite material samples using coal tar pitch. The conventional medium-coarse structure graphite material formulation is adopted, and the preparation process is as follows: calcined coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder content 26%, modified coal tar pitch accounting for 15.5% of the mass of calcined coke, kneading temperature 165℃, kneading time 25min, after kneading the paste is transferred into a mold and statically pressed to obtain medium-coarse structure graphite material green body.

[0089] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0090] Comparative Example 5:

[0091] A method for preparing a carbon material includes the following steps:

[0092] Step 1: Prepare particle size D using Raymond mill and high-energy air jet mill. 50 It is a calcined petroleum coke aggregate with a particle size of 25 μm.

[0093] Step 2: Place the calcined coke aggregate from Step 1 into a 120℃ oven to remove moisture for 3 hours.

[0094] Step 3: Weigh 1g of dibutyl phthalate, 2g of wash oil, and 1g of carboxymethyl cellulose into a 500mL three-necked flask. Start stirring, heat in an oil bath to 90℃, add 50g of coal tar pitch, stir at a constant temperature for 40min, stop the reaction and allow it to cool naturally to room temperature to obtain modified coal tar pitch.

[0095] Step 4: Prepare medium-coarse structure graphite material samples using coal tar pitch. The conventional medium-coarse structure graphite material formulation is adopted, and the preparation process is as follows: calcined coke particle size distribution: 6-3mm content 24%, 3-1mm content 24%, 1-0.076mm content 26%, powder content 26%, modified coal tar pitch accounting for 15.5% of the mass of calcined coke, kneading temperature 165℃, kneading time 25min, after kneading the paste is transferred into a mold and statically pressed to obtain medium-coarse structure graphite material green body.

[0096] Step 5: The green body is placed in a laboratory roasting furnace for roasting, and samples are taken for analysis and testing. The roasted samples are measured for properties such as density and mechanical strength according to industry standards.

[0097] Figure 1 The results show the wettability test results of different coal tar pitches on calcined coke in Examples 1-4 and Comparative Examples 1-5. Figure 2 The images show SEM images of the carbon materials obtained in Examples 1-4 and Comparative Examples 1-5. As can be seen from the images, modified coal tar pitch significantly improves the wetting effect on calcined coke. Furthermore, the medium-coarse structure graphite material prepared from modified coal tar pitch with added additives significantly improves its bulk density and reduces porosity.

[0098] Performance tests were conducted on the calcined samples obtained in Examples 1-4 and Comparative Examples 1-5. The residual carbon value of the asphalt was typically tested using the high-temperature ignition method or the Concorde carbon method. During the test, a certain amount of coal tar pitch sample was placed in a crucible and gradually heated to approximately 500-550°C under air-free conditions, allowing the light components and volatiles to completely volatilize. The remaining carbonaceous portion is the residual carbon. After the sample cooled, the mass of the residue was weighed to obtain the residual carbon value of the asphalt. The green density and calcined density were determined by weighing and volume measurement. First, the dry weight of the sample was measured using a precise electronic balance. Then, the volume of the sample was measured using the immersion method. The density was calculated by dividing the sample's mass by its volume. Porosity determination relied on Archimedes' principle, involving measuring the sample's mass in dry, wet, and suspended states. By measuring the sample's mass under different conditions, the porosity could be accurately calculated. Compressive strength testing was performed using a specialized compression testing machine. In the test, uniform pressure was applied to the sample until fracture occurred, and the maximum load was recorded. Compressive strength was calculated by dividing the maximum load by the sample's original cross-sectional area. Flexural strength was determined using a three-point bending test method. In this test, the anode sample was placed between two supports, with the center point subjected to force until fracture. Flexural strength was calculated based on the applied force and the sample's dimensions. The results are shown in Table 1 below.

[0099] Table 1: Performance test results of calcined samples

[0100]

[0101] As shown in Table 1, the medium-coarse structure graphite materials in Examples 1-4 have high green density and calcined density, as well as high flexural and compressive strength. Among them, the calcined product of Example 1 has a density of 1.68 g / cm³. 3The compressive strength reached 32 MPa and the flexural strength reached 10 MPa, which is excellent. This shows that the method of the present invention can indeed improve the wetting effect of the binder on the aggregate, improve the interaction between the two, and finally obtain a homogeneous, strong interphase interface force, well-matched particle size, high bulk density and excellent comprehensive performance medium-coarse structure graphite material.

[0102] As demonstrated in Example 1 and Comparative Examples 1-3, a single modifying component or two components cannot simultaneously regulate the intermolecular forces of pitch molecules and the interfacial tension between coal tar pitch and coke. Example 1, through the synergistic effect of plasticizers, synergists, and additives, achieved a multiple balance between viscosity control, dispersion stability, and interfacial wetting, enabling coal tar pitch to uniformly penetrate the aggregate micropores at low viscosity, forming a dense coating layer, thereby significantly improving the mechanical properties and thermal stability of the carbon material.

[0103] As can be seen from Example 1 and Comparative Examples 4-5, the reaction temperature also has a great influence on the performance of the final product. The modified coal tar pitch obtained within the reaction temperature range of the present invention has the best fluidity, uniformity and thermal stability.

Claims

1. A method for preparing modified coal tar pitch, characterized in that, The process includes the following steps: mixing plasticizer, synergist and additive, then adding coal tar pitch, stirring, heating to 140-160℃, and reacting at a constant temperature to obtain the modified coal tar pitch. The plasticizer includes dibutyl phthalate and / or dioctyl phthalate; the synergist includes one or more of light oil, naphthalene oil, wash oil, phenolic oil and anthracene oil; the additive includes carboxymethyl cellulose and / or sodium polyacrylate. The mass ratio of the plasticizer, the additive, and the synergist is (1-2):(1-2):2; the mass ratio of the plasticizer and coal tar pitch is (1-3):

100. When mixing plasticizers, synergists and additives, first mix the three together, start stirring, and heat in an oil bath to 100-110℃.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the synergist to coal tar pitch is (2-6):

100.

3. The preparation method according to claim 1 or 2, characterized in that, When reacting at a constant temperature, the reaction time should be controlled to be 1-3 hours.

4. A method for preparing a carbon material, characterized in that, Includes the following steps: Calcined coke aggregate and modified coal tar pitch are mixed and kneaded. The kneaded paste is then statically pressed into shape and then calcined to obtain the carbon material. The modified coal tar pitch is the modified coal tar pitch prepared by the preparation method according to any one of claims 1-3.

5. The preparation method according to claim 4, characterized in that, The mass of the modified coal tar pitch is 15%-17% of the mass of the calcined coke aggregate.

6. The preparation method according to claim 4, characterized in that, The mixing temperature is 160-170℃, and the mixing time is 20-30 minutes.

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