A method for preparing an impregnating agent for graphite

Abstract

This invention belongs to the field of chemical technology, specifically relating to a method for preparing an impregnating agent for graphite, comprising the following steps: (1) mixing an aromatic hydrocarbon polymer with an organic solvent, and then mixing it with medium-temperature coal tar pitch to obtain liquid-phase pre-prepared pitch; the aromatic hydrocarbon polymer is the remaining product after evaporation and purification of 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone at 120-160℃; (2) allowing the mixture to settle and separate into layers, and taking the upper extract to obtain refined pitch containing solvent; (3) obtaining refined pitch after separating the organic solvent; (4) obtaining mesophase microspheres through thermal polymerization; (5) removing the remaining light components in the mesophase microspheres to obtain the impregnating agent for graphite. This invention finds that by using an aromatic hydrocarbon condensate polymer without quinoline insolubles as one of the raw materials, the quinoline insoluble content of the product is reduced without reducing the functional performance of the impregnating agent, the softening point is moderate, and the production cost is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a method for preparing an impregnating agent for graphite. Background Technology

[0002] Impregnating agents are used in the impregnation process of graphite materials and are one of the important raw materials for the production of graphite materials. Their quality directly affects the performance and application range of graphite products.

[0003] Currently, graphite impregnating agents are mainly produced through thermal reforming of medium-temperature coal tar pitch, resulting in a relatively limited source of raw materials. Medium-temperature coal tar pitch is the distillation residue after removing light fractions from coal tar. It consists of aromatic compounds with three or more rings, oxygen-, nitrogen-, and sulfur-containing heterocyclic compounds, and a small amount of high-molecular-weight carbonaceous substances, with a molecular weight between 200 and 2000.

[0004] The main performance indicators of graphite impregnating agents include softening point, quinoline insolubles, ash content, and coking value. Using medium-temperature coal tar pitch directly as an impregnating agent is not feasible because it contains a high amount of quinoline insolubles. These quinoline insolubles, along with ash, hinder the fusion of mesophase carbon microspheres, directly affecting the resistivity and purity of graphite products. Industries such as new energy battery materials and semiconductors have strict requirements on the purity of graphite components used; therefore, it is necessary to remove ash and quinoline insolubles from the impregnating agent as much as possible. Generally, the quinoline insoluble content of medium-temperature coal tar pitch is around 5%. A high quinoline insoluble content can cause problems such as low graphite strength and short service life, requiring specific technical means to reduce the quinoline insoluble content in the impregnating agent.

[0005] The softening point is related to the temperature of the graphite product molding and impregnation process. Only when impregnated with raw coke at a temperature higher than the softening point of the impregnating agent can the impregnating agent effectively wet the surface of the coke and fill the voids in the petroleum coke. The coking value of the impregnating agent is directly related to the carbonization yield during the roasting of the graphite product. The higher the coking value of the impregnating agent, the higher the carbonization yield, the higher the bulk density of the produced graphite product, the greater the mechanical strength, and the lower the resistivity.

[0006] In summary, there is an urgent need to provide a method for preparing a graphite impregnating agent that can effectively reduce the content of quinoline insolubles and has a suitable softening point. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a graphite impregnating agent that can effectively reduce the content of quinoline insolubles and has a suitable softening point.

[0008] The above objective is achieved through the following technical solution: a method for preparing an impregnating agent for graphite, comprising the following steps:

[0009] (1) Raw material mixing: The aromatic hydrocarbon polymer is mixed with an organic solvent, and then the mixture is mixed with medium-temperature coal tar pitch to obtain liquid-phase pre-prepared pitch; wherein, the aromatic hydrocarbon polymer is the remaining product after evaporation and purification of 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone at 120-160℃.

[0010] (2) Impregnation and sedimentation: The precast asphalt in step (1) is impregnated with organic solvent, allowed to settle and separate into layers, and the upper extract is taken to obtain refined asphalt containing solvent.

[0011] (3) Vacuum distillation: The refined asphalt containing solvent in step (2) is separated from the organic solvent by vacuum distillation to obtain refined asphalt;

[0012] (4) Thermal polymerization reaction: The refined asphalt in step (3) is reacted at a predetermined temperature and pressure for a predetermined time to obtain mesophase microspheres;

[0013] (5) Reduced pressure flash evaporation: Remove the remaining light components in the mesophase microspheres in step (4) to obtain the graphite impregnating agent.

[0014] In specific applications, in step (1), after the aromatic polymer to be prepared is cooled, the prepared organic solvent is directly added to the evaporator and stirred at a temperature lower than the boiling point of the organic solvent components, thereby reducing the viscosity of the polymer system.

[0015] The applicant discovered through experiments that the residual product (aromatic hydrocarbon polymer) after evaporation and purification of the reaction of 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone at 120–160 °C is a polycyclic aromatic hydrocarbon. The resin polymer formed by the reaction of 2-hydroxy-5-nonylbenzaldehyde or 2-hydroxy-5-nonylphenylacetone at high temperatures has a complex reaction system, and the possible reaction mechanisms are as follows: Figure 2 As shown, the physicochemical properties of this product are similar to those of asphalt. The target molecular weight can be obtained by adjusting the polymerization degree of the aromatic hydrocarbon polymer through adjusting the reaction time and temperature, thereby regulating the softening point. Moreover, the addition of this aromatic hydrocarbon polymer reduces the quinoline insoluble content without reducing the functional performance of the impregnating agent. This effectively solves the technical problem that many impregnating agents prepared using medium-temperature coal tar pitch contain high levels of quinoline insolubles, which hinder the fusion of mesophase carbon microspheres and directly affect the resistivity and purity of graphite products. This invention introduces a new raw material and medium-temperature coal tar pitch to prepare graphite impregnating agents. Experimental verification shows that this impregnating agent has a low quinoline insoluble content and a moderate softening point, and its use as a graphite impregnating agent will not reduce the performance of graphite products.

[0016] A further technical solution is that the aromatic hydrocarbon polymer is the residual product after evaporation and purification of the copper extractant prepared from 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone. Thus, the aromatic hydrocarbon polymer used to prepare graphite impregnating agents with medium-temperature coal tar pitch is itself a byproduct of the copper extractant preparation process using 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone, effectively utilizing byproducts from the chemical industry and reducing the production cost of graphite impregnating agents.

[0017] A further technical solution is that, in step (1), the 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone are heated in multiple stages from 120°C to 160°C to control the molecular weight of the generated aromatic hydrocarbon polymer to be between 1000 and 1400.

[0018] A further technical solution is to control the molecular weight of the aromatic hydrocarbon polymer to be between 1000 and 1200 within a temperature gradient of 120°C to 160°C, with each gradient maintained for 1 hour, and the softening point of the aromatic hydrocarbon polymer to be controlled between 80 and 100°C.

[0019] A further technical solution is that the ratio of aromatic hydrocarbon polymer, organic solvent, and medium-temperature coal tar pitch in the liquid-phase precast asphalt is 5-10:60-80:30-50. Preferably, the ratio of aromatic hydrocarbon polymer, organic solvent, and medium-temperature coal tar pitch in the liquid-phase precast asphalt is 5-10:70-80:30-35.

[0020] A further technical solution is that the reaction temperature in step (4) is 400-500℃, the reaction pressure is 1-1.5MPaG, and the reaction time is 6-16 hours.

[0021] A further technical solution is that, in step (5), the remaining light components are removed in a vacuum flash evaporator, and the product discharged from the bottom is the graphite impregnating agent. Preferably, the vacuum flash evaporation pressure is 50–300 mmHg, and the temperature is 300–460 °C.

[0022] In the specific application process, refined asphalt is transported to a thermal polymerization reactor, and the reactor is pressurized and heated to react and obtain mesophase microspheres. Some light components generated by the thermal polymerization reaction escape from the top of the reactor. After condensation, they are collected together with the light components in step (5). After collection, they can be used for cleaning stains on chemical reaction vessels.

[0023] A further technical solution is that, in step (3), the separated light components are refluxed and recycled and used to prepare the organic solvent in step (1). The separation temperature of vacuum distillation is 80-120℃, the separation pressure is 100-300mmHg, and the content of quinoline insoluble matter in the refined asphalt obtained is ≤0.5%.

[0024] The content of quinoline insoluble matter in refined asphalt was determined according to the "Test Method for Quinoline Insoluble Matter in Coking Asphalt Products" (GB / T2293-2019), and the content of quinoline insoluble matter in refined asphalt was ≤0.5%. Preferably, the separation temperature was 110℃ and the separation pressure was 250mmHg.

[0025] A further technical solution is that, in step (3), the light component from distillation is condensed and refluxed to a collection tank for preparing organic solvent. Distillation is stopped when there is no liquid flow through the sight glass of the collection tank pipeline. Preferably, the ratio of newly added organic solvent to recycled solvent in the collection tank is 1:0.4 to 0.6, and the temperature of the reaction system is cooled to <80°C when the organic solvent is added.

[0026] A further technical solution is that, in step (2), the precast asphalt is placed in a mixing tank and heated and mechanically stirred. After the precast asphalt is fully impregnated, it is allowed to settle. The stirring time is 1-4 hours, the stirring temperature is 60-80℃, and the settling time is 1-12 hours. Then, the upper extract is taken. Specifically, the lower bottom material can be used as paving asphalt after the solvent is removed by vacuum distillation. Preferably, the stirring time is 2 hours, the stirring temperature is 80℃, and the settling time is 2 hours.

[0027] A further technical solution is that the organic solvent includes one or more of tetrachloroethylene, white oil, quinoline, heptane, anthracene oil, and wash oil. Preferably, the organic solvent used is tetrachloroethylene, quinoline, or white oil, with a component ratio of 1:0.4–0.8:0.2–0.6.

[0028] Compared with existing technologies, this invention is not only simple and economical in process, but also effectively utilizes by-products of the chemical industry to reduce the production cost of graphite impregnating agents. At the same time, the graphite impregnating agent prepared has a low content of quinoline insolubles and a moderate softening point. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 A process flow diagram for preparing a graphite impregnating agent according to one embodiment of the present invention;

[0031] Figure 2 This invention relates to a possible reaction mechanism between 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings. This description is merely illustrative and explanatory, and should not be construed as limiting the scope of protection of the present invention. Furthermore, those skilled in the art can combine the features in the embodiments described herein and in different embodiments accordingly based on the description in this document.

[0033] Example 1

[0034] The preparation method of the graphite impregnating agent is as follows, such as... Figure 1 :

[0035] (1) Raw material mixing: 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone were purified by evaporation in a falling film evaporator. The evaporation temperature range was 120-160℃, with a gradient of 10℃ within the 120℃-160℃ range, and each gradient was maintained for 1 hour. The remaining polymer weight in the reactor was about 8%, resulting in an aromatic hydrocarbon polymer. Gel chromatography analysis showed that the molecular weight of the aromatic hydrocarbon polymer was between 1000 and 1200, and the softening point of the aromatic hydrocarbon polymer was controlled between 80 and 100℃. After evaporation, the falling film evaporator was cooled to 70℃, and a new organic solvent was introduced for mixing. The organic solvent contained tetrachloroethylene, quinoline, and white oil, with a weight ratio of 1:0.5:0.3 for each component. The mixed mixture was then fed into an asphalt mixing tank and mixed with medium-temperature coal tar pitch to produce liquid-phase pre-asphalt. The weight ratio of aromatic hydrocarbon polymer: organic solvent: medium-temperature asphalt in the liquid-phase pre-asphalt was 10:80:30.

[0036] (2) Impregnation and sedimentation: The precast asphalt in step (1) is impregnated with organic solvent, heated and mechanically stirred, and allowed to settle and separate into layers. The stirring time is 2 hours, the stirring temperature is 80℃, and the settling time is 2 hours. After sedimentation and separation, the upper extract is taken to obtain refined asphalt containing solvent.

[0037] (3) Vacuum distillation: The refined asphalt containing solvent in step (2) is separated from the organic solvent by vacuum distillation to obtain refined asphalt; the distillation temperature is selected as 110℃ and the pressure is 250mmHg. After distillation, the quinoline insoluble content of the refined asphalt is tested to be 0.26%.

[0038] (4) Thermal polymerization reaction: The refined asphalt is transported to the thermal polymerization reactor, and the reaction is carried out under pressure and temperature to obtain mesophase microspheres. Some light components generated by the thermal polymerization reaction escape from the top of the reactor. After condensation, they are collected together with the light components in step (5). After collection, they can be used for cleaning stains on chemical reaction vessels. Specifically, the reaction temperature is 420℃, the reaction pressure is 1.0MPaG, and the reaction time is 6 hours.

[0039] (5) Vacuum flash evaporation: Pump the material at the bottom of the reactor in step (4) into a vacuum flash evaporator to remove the remaining light components in the mesophase microspheres and obtain graphite impregnating agent 1. The vacuum flash evaporation pressure is 200 mmHg, the temperature is 400℃, and the yield is 76.1%.

[0040] Example 2

[0041] The preparation method of the graphite impregnating agent is as follows, such as... Figure 1 :

[0042] (1) Raw material mixing: 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone were purified by evaporation in a falling film evaporator. The evaporation temperature range was 120-160℃. Within the range of 120℃ to 160℃, the temperature was increased in increments of 10℃, with each increment lasting for 1 hour. The remaining polymer weight in the reactor was approximately 8%, yielding an aromatic hydrocarbon polymer. Gel chromatography analysis showed that the molecular weight of the aromatic hydrocarbon polymer was between 1000 and 1200, and the softening point of the aromatic hydrocarbon polymer was controlled between 80 and 100℃. After evaporation, the falling film evaporator was cooled to 70℃. The fresh organic solvent was mixed with the organic solvent recovered in the collection tank at a ratio of fresh organic solvent to recycled organic solvent of 1:0.4. The organic solvent contained tetrachloroethylene, quinoline, and white oil, with a weight ratio of 1:0.5:0.3 for each component. The mixed mixture is fed into an asphalt mixing tank and mixed with medium-temperature coal tar pitch to produce liquid-phase pre-asphalt. The weight ratio of aromatic polymer, organic solvent and medium-temperature asphalt in the liquid-phase pre-asphalt is 10:80:30.

[0043] (2) Impregnation and sedimentation: The precast asphalt in step (1) is impregnated with organic solvent, heated and mechanically stirred, and allowed to settle and separate into layers. The stirring time is 2 hours, the stirring temperature is 80℃, and the settling time is 2 hours. After sedimentation and separation, the upper extract is taken to obtain refined asphalt containing solvent.

[0044] (3) Vacuum distillation: The refined asphalt containing solvent in step (2) is subjected to vacuum distillation to separate the organic solvent, and then the organic solvent is condensed and refluxed into a collection tank. The distillation temperature is 110℃ and the pressure is 250mmHg. After distillation, the quinoline insoluble content of the refined asphalt is 0.27%.

[0045] (4) Thermal polymerization reaction: The refined asphalt is transported to the thermal polymerization reactor, and the reaction is carried out under pressure and temperature to obtain mesophase microspheres. Some light components generated by the thermal polymerization reaction escape from the top of the reactor. After condensation, they are collected together with the light components in step (5). After collection, they can be used for cleaning stains on chemical reaction vessels. Specifically, the reaction temperature is 420℃, the reaction pressure is 1.0MPaG, and the reaction time is 6 hours.

[0046] (5) Vacuum flash evaporation: Pump the material at the bottom of the reactor in step (4) into a vacuum flash evaporator to remove the remaining light components in the mesophase microspheres and obtain graphite impregnating agent 2. The vacuum flash evaporation pressure is 200 mmHg, the temperature is 400℃, and the yield is 76.9%.

[0047] Example 3

[0048] The preparation method of the graphite impregnating agent is as follows, such as... Figure 1 :

[0049] (1) Raw material mixing: 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone were purified by evaporation in a falling film evaporator. The evaporation temperature range was 120-160℃. Within the range of 120℃ to 160℃, the temperature was increased in increments of 10℃, with each increment lasting for 1.4 hours. The remaining polymer weight in the reactor was approximately 8%, yielding an aromatic hydrocarbon polymer. Gel chromatography analysis showed that the molecular weight of the aromatic hydrocarbon polymer was between 1200 and 1400, and the softening point of the aromatic hydrocarbon polymer was controlled between 80 and 100℃. After evaporation, the falling film evaporator was cooled to 70℃. The fresh organic solvent was mixed with the organic solvent recovered in the collection tank at a ratio of fresh organic solvent to recycled organic solvent of 1:0.4. The organic solvent contained heptane, anthracene oil, and wash oil, with a weight ratio of 1:0.5:0.3 for each component. The mixed mixture is fed into an asphalt mixing tank and mixed with medium-temperature coal tar pitch to form liquid-phase pre-asphalt, wherein the weight ratio of aromatic polymer: organic solvent: medium-temperature asphalt in the liquid-phase pre-asphalt is 5:60:50.

[0050] (2) Impregnation and sedimentation: The precast asphalt in step (1) is impregnated with organic solvent, heated and mechanically stirred, and allowed to settle and separate into layers. The stirring time is 4 hours, the stirring temperature is 60℃, and the settling time is 12 hours. After sedimentation and separation, the upper extract is taken to obtain refined asphalt containing solvent.

[0051] (3) Vacuum distillation: The refined asphalt containing solvent from step (2) is subjected to vacuum distillation to separate the organic solvent, and then the organic solvent is condensed and refluxed into a collection tank. The distillation temperature is 80℃ and the pressure is 300mmHg. After distillation, the quinoline insoluble content of the refined asphalt is 0.3%.

[0052] (4) Thermal polymerization reaction: The refined asphalt is transported to the thermal polymerization reactor, and the reaction is carried out under pressure and temperature to obtain mesophase microspheres. Some light components generated by the thermal polymerization reaction escape from the top of the reactor. After condensation, they are collected together with the light components in step (5). After collection, they can be used for cleaning stains on chemical reaction vessels. Specifically, the reaction temperature is 400℃, the reaction pressure is 1.5MPaG, and the reaction time is 10 hours.

[0053] (5) Vacuum flash evaporation: Pump the material at the bottom of the reactor in step (4) into the vacuum flash evaporator to remove the remaining light components in the mesophase microspheres and obtain graphite impregnating agent 3. The vacuum flash evaporation pressure is 300 mmHg, the temperature is 300℃, and the yield is 77.3%.

[0054] Example 4

[0055] The preparation method of the graphite impregnating agent is as follows, such as... Figure 1 :

[0056] (1) Raw material mixing: 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone were purified by evaporation in a falling film evaporator. The evaporation temperature range was 120-160℃. Within the range of 120℃ to 160℃, the temperature was increased in increments of 10℃, with each increment lasting for 1.2 hours. The remaining polymer weight in the reactor was approximately 8%, yielding an aromatic hydrocarbon polymer. Gel chromatography analysis showed that the molecular weight of the aromatic hydrocarbon polymer was between 1200 and 1300, and the softening point of the aromatic hydrocarbon polymer was controlled between 80 and 100℃. After evaporation, the falling film evaporator was cooled to 70℃. The fresh organic solvent was mixed with the organic solvent recovered in the collection tank at a ratio of fresh organic solvent to recycled organic solvent of 1:0.6. The organic solvent contained tetrachloroethylene, quinoline, and white oil, with a weight ratio of 1:0.8:0.2 for each component. The mixed mixture is fed into an asphalt mixing tank and mixed with medium-temperature coal tar pitch to produce liquid-phase pre-asphalt. The weight ratio of aromatic polymer, organic solvent and medium-temperature asphalt in the liquid-phase pre-asphalt is 8:80:40.

[0057] (2) Impregnation and sedimentation: The precast asphalt in step (1) is impregnated with organic solvent, heated and mechanically stirred, and allowed to settle and separate into layers. The stirring time is 1 hour, the stirring temperature is 70℃, and the settling time is 1 hour. After sedimentation and separation, the upper extract is taken to obtain refined asphalt containing solvent.

[0058] (3) Vacuum distillation: The refined asphalt containing solvent in step (2) is subjected to vacuum distillation to separate the organic solvent, and then the organic solvent is condensed and refluxed into a collection tank. The distillation temperature is 120℃ and the pressure is 100mmHg. After distillation, the quinoline insoluble content of the refined asphalt is 0.24%.

[0059] (4) Thermal polymerization reaction: The refined asphalt is transported to the thermal polymerization reactor, and the reaction is carried out under pressure and temperature to obtain mesophase microspheres. Some light components generated by the thermal polymerization reaction escape from the top of the reactor. After condensation, they are collected together with the light components in step (5). After collection, they can be used for cleaning stains on chemical reaction vessels. Specifically, the reaction temperature is 500℃, the reaction pressure is 1.2MPaG, and the reaction time is 16 hours.

[0060] (5) Vacuum flash evaporation: Pump the material at the bottom of the reactor in step (4) into a vacuum flash evaporator to remove the remaining light components in the mesophase microspheres and obtain graphite impregnating agent 4. The vacuum flash evaporation pressure is 50 mmHg, the temperature is 460℃, and the yield is 75.3%.

[0061] Comparative Example 1

[0062] Except for the absence of the byproduct (aromatic polymer) after evaporation and purification of 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone in a falling film evaporator, the process is the same as in Example 1.

[0063] The product property test results of the graphite impregnating agents prepared in Examples 1-4 and Comparative Example 1 are listed in Table 1. As shown in Table 1, the products of Examples 1-4 can all be used as graphite impregnating agents. Compared to the product of Comparative Example 1, which only used medium-temperature coal tar pitch, the products of Examples 1-4, which used medium-temperature coal tar pitch and aromatic polymer as raw materials, had higher coking values ​​and lower quinoline insoluble content, similar yields, and moderate softening points. Furthermore, comparing the products of Examples 1 and 2, the product of Example 2 used recycled solvent, yet its product properties were similar, its yield was close, and solvent recovery could reduce costs.

[0064] Table 1. Properties of products prepared in each embodiment and comparative example.

[0065]

[0066]

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an impregnating agent for graphite, characterized in that, Includes the following steps: (1) Raw material mixing: The aromatic hydrocarbon polymer is mixed with an organic solvent, and then the mixture is mixed with medium-temperature coal tar pitch to obtain liquid-phase pre-prepared pitch; wherein, the aromatic hydrocarbon polymer is the remaining product after evaporation and purification of 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone at 120~160 °C. (2) Impregnation and sedimentation: The precast asphalt in step (1) is impregnated with organic solvent, allowed to settle and separate into layers, and the upper extract is taken to obtain refined asphalt containing solvent. (3) Vacuum distillation: The refined asphalt containing solvent in step (2) is separated from the organic solvent by vacuum distillation to obtain refined asphalt; (4) Thermal polymerization reaction: The refined asphalt in step (3) is reacted at a predetermined temperature and pressure for a predetermined time to obtain mesophase microspheres; (5) Reduced pressure flash evaporation: Remove the remaining light components in the mesophase microspheres in step (4) to obtain the graphite impregnating agent; The aromatic hydrocarbon polymer is the remaining product after evaporating and purifying the copper extractant by preparing a copper extractant from 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone. In step (1), the 2-hydroxy-5-nonylbenzaldehyde and 2-hydroxy-5-nonylphenylacetone are heated in multiple stages from 120°C to 160°C to control the molecular weight of the generated aromatic hydrocarbon polymer to be between 1000 and 1400.

2. The method for preparing the graphite impregnating agent according to claim 1, characterized in that, Within the range of 120℃ to 160℃, in increments of 10℃, each gradient is maintained for 1 hour, controlling the molecular weight of the aromatic hydrocarbon polymer to be between 1000 and 1200, and controlling the softening point of the aromatic hydrocarbon polymer to be between 80 and 100℃.

3. The method for preparing the graphite impregnating agent according to claim 2, characterized in that, The ratio of aromatic hydrocarbon polymer, organic solvent and medium-temperature coal tar pitch in the liquid-phase precast asphalt is 5~10:60~80:30~50.

4. The method for preparing the graphite impregnating agent according to any one of claims 1 to 3, characterized in that, The reaction temperature in step (4) is 400~500℃, the reaction pressure is 1~1.5 MPaG, and the reaction time is 6~16 hours.

5. The method for preparing the graphite impregnating agent according to any one of claims 1 to 3, characterized in that, In step (3), the separated light components are refluxed and recycled and used to prepare the organic solvent in step (1). The separation temperature of vacuum distillation is 80~120℃, the separation pressure is 100-300 mmHg, and the content of quinoline insoluble matter in the refined asphalt obtained is ≤0.5%.

6. The method for preparing the graphite impregnating agent according to claim 5, characterized in that, In step (3), the distilled light components are condensed and refluxed to the collection tank for the preparation of organic solvents. Distillation is stopped when there is no liquid flow through the sight glass of the collection tank pipeline.

7. The method for preparing the graphite impregnating agent according to claim 5, characterized in that, In step (2), the precast asphalt is placed in a mixing tank and heated and mechanically stirred. After the precast asphalt is fully impregnated, it is allowed to settle. The stirring time is 1 to 4 hours, the stirring temperature is 60 to 80 ℃, and the settling time is 1 to 12 hours. Then the upper extract is taken.

8. The method for preparing the graphite impregnating agent according to claim 1, characterized in that, The organic solvent includes one or more of tetrachloroethylene, white oil, quinoline, heptane, anthracene oil, and wash oil.

Images