Peanut shell-based biomass carbon black and application thereof in cable shielding material

Abstract

The invention relates to the technical field of power cable materials, in particular to peanut shell-based biomass carbon black and application of the peanut shell-based biomass carbon black to a cable shielding material, and a preparation method of the peanut shell-based biomass carbon black comprises the following specific steps: S1, raw material pretreatment; s2, primary pre-carbonization; s3, carbon powder activation; and S4, carrying out secondary carbonization. The cable shielding material is prepared from 58-60% by mass of the peanut shell-based biomass carbon black, 38-40% by mass of linear low density polyethylene, 1-2% by mass of an antioxidant and 1-2% by mass of white oil. Compared with the prior art, the method has the following beneficial effects that the zinc chloride in the activation stage is used as Lewis acid in the high-temperature pyrolysis process and is subjected to dehydration reaction with cellulose, lignin and other components in the biomass to promote aromatization crosslinking and inhibit tar generation, so that a stable porous carbon skeleton is formed, the conductivity, chemical stability and filler dispersity of the carbon black are remarkably enhanced, and the carbon black has a good application prospect. The high requirement of the cable shielding material on the functional filler is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power cable materials, in particular to peanut shell-based biomass carbon black and its application in cable shielding materials. BACKGROUND

[0002] Biomass energy is an important resource that is converted from solar energy by chlorophyll in green plants, which is indispensable to human survival. Biomass energy is considered as a potential alternative to fossil energy, which can be directly used as a carbon source to produce solid, liquid and gaseous fuels, and can be converted into energy and chemical products through other technologies. In recent years, with the global emphasis on environmental protection and sustainable development, biomass carbon black has received extensive attention due to its advantages of being renewable, environmentally friendly, widely available raw materials, and reducing dependence on petroleum resources. Biomass carbon black is prepared by pyrolysis of biomass materials, and has a porous structure, a high specific surface area, and adjustable electrical conductivity, which has great application potential in cable shielding materials, rubber products, coatings, and other fields. Commonly used biomass includes wood, straw, rice husk, and fruit shells, among which peanut shells are an important resource. As an abundant agricultural waste, peanut shells have a high carbon content, making them an ideal raw material for biomass carbon black. Peanut shell-based carbon black has the advantages of low cost, wide availability, and environmental friendliness. If it can be combined with the matrix of cable shielding materials, not only can the cost of raw materials be effectively reduced, but also the environmental friendliness and sustainability of the composite material can be improved.

[0003] Cable shielding material is a necessary structure for medium and high voltage cables, which plays an important role in shielding electromagnetic interference, protecting the internal insulation layer of the cable, and ensuring stable transmission of power signals. Its core function is to dissipate or reflect electromagnetic interference (EMI) through a conductive network to ensure signal integrity and equipment safety, which is the "invisible shield" of the power transmission system. Traditional cable shielding materials use petroleum-based carbon black as conductive filler. The technology of combining petroleum-based carbon black conductive filler with high molecular polymer can effectively realize the development of cable shielding composites. However, traditional cable shielding materials are derived from petroleum chemicals, which have complex preparation processes, non-renewable raw materials, and high prices. In addition, the surface of carbon black is inert, which leads to weak interfacial adhesion between carbon black and polyethylene (PE), ethylene-vinyl acetate (EVA), and other matrices. High filler content can easily cause material brittleness and thermal stability degradation. Biomass carbon has certain electrical conductivity, and through pyrolysis-activation process, it can construct a multi-level pore structure and high conductivity network, providing a green alternative for cable shielding materials. Compared with petroleum-based carbon black, biomass carbon black has the advantages of renewable raw materials and low cost, and its surface is rich in active groups such as hydroxyl (-OH) and carboxyl (-COOH), which can form chemical bonds with polymer matrices to improve interfacial adhesion strength. SUMMARY

[0004] The present application aims to solve the technical problems existing in the background art, and therefore provides a peanut shell-based biomass carbon black.

[0005] The peanut shell-based biomass carbon black, a preparation method thereof, and specific steps are as follows:

[0006] S1, raw material pretreatment

[0007] The waste peanut shell powder is placed in deionized water for ultrasonic cleaning to remove the mud and soluble impurities attached to the surface. Then, the peanut shell is mixed with a 10% mass concentration of sodium hydroxide solution at a solid-liquid ratio of 1:8. After stirring in a 70-80°C water bath for 3-5 hours, the peanut shell is washed with deionized water until it is neutral. After drying, the pretreated peanut shell is obtained.

[0008] S2, first pre-carbonization

[0009] The pretreated peanut shell is pre-carbonized in a tube furnace at 350-450°C for 1 hour to promote the breakage of lignin side chains to generate small molecular volatile substances. Then, the temperature is increased to 750-850°C, and the pre-carbonization is continued for 3 hours under nitrogen protection. After the pretreated peanut shell is ground by a planetary ball mill for 15 minutes and then passed through a 100-mesh sieve, the carbon powder is obtained.

[0010] S3, carbon powder activation

[0011] The carbon powder is immersed in a 40% mass concentration of zinc chloride solution, and after continuous stirring in a 75°C constant temperature water bath for 24 hours, it is placed in a tube furnace for activation. The temperature is increased to 800°C at a rate of 10°C / min under a nitrogen atmosphere, and the temperature is maintained for 1 hour. Then, the carbon powder is washed with deionized water and anhydrous ethanol for 15 minutes each time, and the process is repeated three times to completely remove the residual zinc salt and pyrolysis by-products. After washing, the activated carbon powder is treated in a 80°C vacuum drying oven for 24 hours.

[0012] S4, second carbonization

[0013] The activated carbon powder is taken to a tube furnace for second carbonization using a program-controlled tube furnace. The carrier gas is nitrogen, the gas flow rate is 300 mL / min, and the heating rate is 5°C / min. After the temperature is increased to 1300-1400°C, the temperature is maintained for 2 hours to obtain the peanut shell-based biomass carbon black.

[0014] As a preferred embodiment of the above technical solution, the particle size of the waste peanut shell powder is less than 2 mm, and the ash content is less than 5%.

[0015] As a preferred embodiment of the above technical solution, the waste peanut shell powder is placed in deionized water for ultrasonic cleaning to remove the mud and soluble impurities attached to the surface. Then, the peanut shell is mixed with a 10% mass concentration of sodium hydroxide solution at a solid-liquid ratio of 1:8. After stirring in a 75°C water bath for 4 hours, the peanut shell is washed with deionized water until it is neutral. After drying, the pretreated peanut shell is obtained.

[0016] As the preferred technical solution of the above, the pretreated peanut shell is pre-carbonized in a tube furnace at 400 DEG C for 1 hour to cause the side chain of lignin to break to generate small molecule volatile substances; then the temperature is raised to 800 DEG C, and the pre-carbonization is continued for 3 hours under nitrogen protection to obtain the pre-carbonized peanut shell; the pre-carbonized peanut shell is ground by a planetary ball mill for 15 min and then passed through a 100 mesh screen to obtain the carbon powder.

[0017] As the preferred technical solution of the above, the activated carbon powder is taken into a tube furnace, and secondary carbonization is carried out by using a program-controlled tube furnace, the carrier gas is nitrogen, the gas flow rate is 300 mL / min, the heating rate is 5 DEG C / min, the temperature is raised to 1350 DEG C, and then the temperature is kept for 2 h to obtain the peanut shell-based biomass carbon black.

[0018] A cable shielding material is prepared from the peanut shell-based biomass carbon black in a mass ratio of 58-60%, linear low density polyethylene in a mass ratio of 38-40%, antioxidant in a mass ratio of 1-2%, and white oil in a mass ratio of 1-2%.

[0019] As the preferred technical solution of the above, a cable shielding material is prepared from the peanut shell-based biomass carbon black in a mass ratio of 60%, linear low density polyethylene in a mass ratio of 38%, antioxidant in a mass ratio of 1%, and white oil in a mass ratio of 1%.

[0020] As the preferred technical solution of the above, the antioxidant is a hindered phenol stabilizer.

[0021] The present application provides a peanut shell-based biomass carbon black and its application in cable shielding material, and has the following beneficial effects:

[0022] 1. The raw material peanut shell is pretreated by sodium hydroxide, which effectively breaks the lignin-carbohydrate complex through saponification reaction, and at the same time avoids excessive hydrolysis of cellulose.

[0023] 2. In the activation stage, zinc chloride acts as a Lewis acid in the high-temperature pyrolysis process, and dehydrates with cellulose, lignin and other components in the biomass, promotes aromatic crosslinking, and inhibits tar generation, thereby forming a stable porous carbon skeleton, significantly enhancing the electrical conductivity, chemical stability and filler dispersibility of the carbon black, and meeting the high requirements of cable shielding material on functional fillers.

[0024] 3、Once pre-carbonization can initially form a carbon skeleton, but often there are problems such as tar and other volatile substances remaining, high ash content, uneven pore size distribution, and insufficient specific surface area. These defects will lead to the difficulty of carbon black in meeting the stringent requirements of medium and high voltage cable shielding materials in terms of electrical conductivity, structural stability and compatibility with the polymer matrix. Residual volatile substances from one carbonization may release gas in a high temperature environment, affecting the stability of the cable insulation layer; ash impurities can destroy the electrical conductivity continuity of the carbon black network; and insufficient pore structure limits its shielding effectiveness of electromagnetic waves.

[0025] Secondary carbonization can effectively solve the above problems by high-temperature treatment of the activated one carbonization product in an inert atmosphere. On the one hand, the high-temperature environment can further remove residual volatile matter and part of the ash, improving the purity of carbon black; on the other hand, the continuous pyrolysis can promote the graphitization transformation of the carbon structure and optimize the pore structure through the shrinkage and reconstruction of the carbon skeleton, thereby significantly enhancing the electrical conductivity, chemical stability and filler dispersibility of carbon black. In order to improve the purity, electrical conductivity and rationality of the pore structure of carbon black, meet the high requirements of cable shielding materials for functional fillers. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The figure is a process flow diagram of the present application. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described in detail below in combination with the embodiments of the present application.

[0028] Example 1

[0029] Peanut shell-based biomass carbon black and its preparation method, the specific steps are as follows:

[0030] S1, raw material pretreatment

[0031] The waste peanut shell powder is placed in deionized water and ultrasonically cleaned to remove the mud and soluble impurities attached to the surface. Then the peanut shell is mixed with a 10% mass concentration of sodium hydroxide solution at a solid-liquid ratio of 1:8, stirred in a water bath at 70°C for 3 hours, then washed with deionized water until neutral, and dried to obtain pretreated peanut shell.

[0032] Further, the waste peanut shell powder has a particle size of <2mm and an ash content of <5%.

[0033] The raw material peanut shell is pretreated with sodium hydroxide, which effectively breaks down the lignin-carbohydrate complex through saponification reaction, while avoiding excessive hydrolysis of cellulose.

[0034] S2, one pre-carbonization

[0035] The pretreated peanut shell is pre-carbonized in a tube furnace at 350°C for 1 hour to break the lignin side chain and generate small molecule volatile substances; then the temperature is raised to 750°C, and the pre-carbonization is continued for 3 hours under nitrogen protection to obtain pre-carbonized peanut shell. The pre-carbonized peanut shell is ground by a planetary ball mill for 15 min and then sieved through a 100-mesh sieve to obtain carbon powder.

[0036] S3, activation of carbon powder

[0037] The carbon powder is immersed in a 40% mass concentration zinc chloride solution, and after continuous stirring in a 75°C constant temperature water bath for 24 h, it is placed in a tube furnace for activation. The temperature is raised to 800°C at a rate of 10°C / min under a nitrogen atmosphere, and the temperature is maintained for 1 h. Finally, the residual zinc salt and pyrolysis by-products are completely removed by repeated ultrasonic cleaning with deionized water and anhydrous ethanol for 15 min each time, for a total of 3 times. After cleaning, the activated carbon powder is treated in a vacuum drying oven at 80°C for 24 h.

[0038] During the activation stage, zinc chloride acts as a Lewis acid in the high-temperature pyrolysis process and dehydrates with components such as cellulose and lignin in biomass, promoting aromatic cross-linking and inhibiting tar generation, thereby forming a stable porous carbon skeleton that significantly enhances the electrical conductivity, chemical stability, and filler dispersibility of carbon black, meeting the high requirements of cable shielding materials for functional fillers.

[0039] S4, secondary carbonization

[0040] The activated carbon powder is taken to a tube furnace for secondary carbonization using a program-controlled tube furnace. The carrier gas is nitrogen, the gas flow rate is 300 mL / min, the heating rate is 5°C / min, the temperature is raised to 1300°C, and the temperature is maintained for 2 h to obtain the peanut shell-based biomass carbon black.

[0041] Although primary pre-carbonization can initially form a carbon skeleton, there are often problems such as the presence of volatile substances such as tar, high ash content, uneven pore size distribution, and insufficient specific surface area. These defects can result in difficulties in meeting the stringent requirements of medium and high voltage cable shielding materials in terms of the electrical conductivity, structural stability, and compatibility with the polymer matrix of carbon black. The residual volatile substances from primary carbonization may release gas in a high-temperature environment, affecting the stability of the cable insulation layer; ash impurities can disrupt the electrical conductivity continuity of the carbon black network; and insufficient pore structure limits the shielding effectiveness of electromagnetic waves.

[0042] Secondary carbonization can effectively solve the above problems by high-temperature treatment of the activated primary carbonization product in an inert atmosphere. On the one hand, the high-temperature environment can further remove residual volatile matter and part of the ash, improving the purity of the carbon black; on the other hand, the continuous pyrolysis can promote the graphitization transformation of the carbon structure and optimize the pore structure through the shrinkage and reconstruction of the carbon skeleton, thereby significantly enhancing the electrical conductivity, chemical stability and filler dispersibility of the carbon black. In order to improve the purity, electrical conductivity and rationality of the pore structure of the carbon black, meet the high requirements of cable shielding materials for functional fillers.

[0043] Example 2

[0044] Peanut shell-based biomass carbon black, its preparation method, the specific steps are as follows:

[0045] S1, raw material pretreatment

[0046] The waste peanut shell powder is placed in deionized water for ultrasonic cleaning to remove the attached sand and soluble impurities on the surface. Then the peanut shell is mixed with a 10% mass concentration of sodium hydroxide solution at a solid-liquid ratio of 1:8, stirred in a water bath at 80°C for 5 hours, then washed with deionized water until neutral, dried to obtain pretreated peanut shell.

[0047] Further, the waste peanut shell powder has a particle size of <2mm and an ash content of <5%.

[0048] S2, primary pre-carbonization

[0049] The pretreated peanut shell is pre-carbonized in a tube furnace at 450°C for 1 hour to promote the breakage of lignin side chains to generate small molecular volatile matter; then heated to 850°C and continued to pre-carbonize for 3 hours under nitrogen protection, to obtain pre-carbonized peanut shell. The pre-carbonized peanut shell is ground by a planetary ball mill for 15 min and then passed through a 100 mesh sieve to obtain carbon powder.

[0050] S3, carbon powder activation

[0051] The carbon powder is immersed in a 40% mass concentration of zinc chloride solution, continuously stirred in a constant temperature water bath at 75°C for 24h, then placed in a tube furnace for activation, heated to 800°C at 10°C / min under nitrogen atmosphere, and kept for 1h. Finally, it is washed with deionized water and anhydrous ethanol for 15 min each time, repeated for 3 times, to completely remove the residual zinc salt and pyrolysis byproducts. After washing, it is treated in a vacuum drying oven at 80°C for 24h to obtain activated carbon powder.

[0052] S4, secondary carbonization

[0053] The activated carbon powder is taken to a tube furnace, secondary carbonization is carried out by using a program-controlled tube furnace, the carrier gas is nitrogen, the gas flow rate is 300 mL / min, heating is carried out at a rate of 5 ℃ / min, and after being heated to 1400 ℃, the temperature is kept for 2 h to obtain the peanut shell-based biomass carbon black.

[0054] Example 3

[0055] A peanut shell-based biomass carbon black, a preparation method thereof, and specific steps are as follows:

[0056] S1, raw material pretreatment

[0057] The waste peanut shell powder is placed in deionized water and ultrasonically cleaned to remove the mud and soluble impurities attached to the surface, then the peanut shell is mixed with a 10% mass concentration of sodium hydroxide solution according to a solid-liquid ratio of 1:8, stirred in a 75 ℃ water bath for 4 hours, then washed with deionized water until neutral, dried, and the pretreated peanut shell is obtained.

[0058] Further, the waste peanut shell powder has a particle size of <2 mm and an ash content of <5%.

[0059] S2, primary pre-carbonization

[0060] The pretreated peanut shell is pre-carbonized at 400 ℃ for 1 h in a tube furnace to promote the rupture of lignin side chains to generate small molecular volatile substances, then heated to 800 ℃, and pre-carbonized for 3 h under nitrogen protection, to obtain pre-carbonized peanut shell, which is ground by a planetary ball mill for 15 min and then passed through a 100-mesh sieve to obtain carbon powder.

[0061] S3, carbon powder activation

[0062] The carbon powder is immersed in a 40% mass concentration of zinc chloride solution, continuously stirred in a 75 ℃ constant temperature water bath for 24 h, then placed in a tube furnace for activation, heated to 800 ℃ at a rate of 10 ℃ / min under a nitrogen atmosphere, kept for 1 h, and then washed with deionized water and anhydrous ethanol for 15 min each time, repeated for 3 times, to completely remove the residual zinc salt and pyrolysis by-products, and after washing, the activated carbon powder is obtained by treating in a 80 ℃ vacuum drying box for 24 h.

[0063] S4, secondary carbonization

[0064] The activated carbon powder is taken to a tube furnace, secondary carbonization is carried out by using a program-controlled tube furnace, the carrier gas is nitrogen, the gas flow rate is 300 mL / min, heating is carried out at a rate of 5 ℃ / min, and after being heated to 1400 ℃, the temperature is kept for 2 h to obtain the peanut shell-based biomass carbon black.

[0065] Comparative Example 1

[0066] The comparative example 1 is compared with the example 1, the only difference is that the carbon powder activation process in S3 is not used, and the carbon powder is directly carbonized after one pre-carbonization, and the other method steps are the same.

[0067] Comparative example 2

[0068] The comparative example 2 is compared with the example 2, the only difference is that the two-step carbonization and activation method in S2, S3 and S4 is not used, but the one-step carbonization method of the existing process is used to carbonize the pretreated peanut shell prepared in S1.

[0069] The graphitization degree of the peanut shell-based biomass carbon black prepared in the above three examples and two comparative examples is tested by using an X-ray diffractometer by using an X-ray diffraction phase analysis technology. The working principle is that the sample is irradiated by X-ray, the material in the material is excited to produce secondary fluorescent X-ray, and then the related parameters of the specific crystal structure are obtained, so as to accurately evaluate the graphitization degree of the peanut shell carbon black, and the results are as follows in Table 1:

[0070] Table 1

[0071]

[0072] As shown in Table 1, the peanut shell-based biomass carbon black prepared by the process of the present application has a higher graphitization degree, which meets the high requirements of cable shielding material on functional fillers.

[0073] Comparative example 3

[0074] The comparative example 3 is compared with the example 3, the only difference is that the secondary carbonization temperature in S4 is increased to 900-1000 DEG C.

[0075] Comparative example 4

[0076] The comparative example 4 is compared with the example 3, the only difference is that the secondary carbonization temperature in S4 is increased to 1100-1200 DEG C.

[0077] Comparative example 5

[0078] The comparative example 3 is compared with the example 3, the only difference is that the secondary carbonization temperature in S4 is increased to 1500-1600 DEG C.

[0079] Comparative example 6

[0080] The comparative example 6 is compared with the example 3, the only difference is that the secondary carbonization temperature in S4 is increased to 1700-1800 DEG C.

[0081] The graphitization degree of the peanut shell-based biomass carbon black prepared in the three examples and comparative examples 3-6 is tested by using an X-ray diffractometer by using an X-ray diffraction phase analysis technology. The results are as follows in Table 2:

[0082] Table 2

[0083]

[0084] As can be seen from Table 2, in the secondary carbonization process, in the range of 900-1400℃, with the increase of carbonization temperature, the graphitization degree of the peanut shell-based biomass carbon shows a significant upward trend, but above 1400℃, the graphitization degree of the peanut shell-based biomass carbon has very limited improvement, therefore, the present application adopts 1300-1400℃ as the secondary carbonization temperature, which is the most economical.

[0085] Example 4

[0086] A cable shielding material is prepared from the peanut shell-based biomass carbon black prepared in Example 1 with a mass ratio of 58%, linear low density polyethylene with a mass ratio of 38%, antioxidant with a mass ratio of 2% and white oil with a mass ratio of 2%.

[0087] Further, the antioxidant is a hindered phenolic stabilizer.

[0088] Example 5

[0089] A cable shielding material is prepared from the peanut shell-based biomass carbon black prepared in Example 2 with a mass ratio of 60%, linear low density polyethylene with a mass ratio of 38%, antioxidant with a mass ratio of 1% and white oil with a mass ratio of 1%.

[0090] Further, the antioxidant is a hindered phenolic stabilizer.

[0091] Example 6

[0092] A cable shielding material is prepared from the peanut shell-based biomass carbon black prepared in Example 3 with a mass ratio of 58%, linear low density polyethylene with a mass ratio of 40%, antioxidant with a mass ratio of 1% and white oil with a mass ratio of 1%.

[0093] Further, the antioxidant is a hindered phenolic stabilizer.

[0094] Comparative Example 7

[0095] In Comparative Example 7, the proportioning of the cable shielding material is adjusted to peanut shell-based biomass carbon black with a mass ratio of 30%, linear low density polyethylene with a mass ratio of 67%, antioxidant with a mass ratio of 1.5% and white oil with a mass ratio of 1.5%.

[0096] Comparative Example 8

[0097] In Comparative Example 8, the proportioning of the cable shielding material is adjusted to peanut shell-based biomass carbon black with a mass ratio of 40%, linear low density polyethylene with a mass ratio of 57%, antioxidant with a mass ratio of 1.5% and white oil with a mass ratio of 1.5%.

[0098] Comparative Example 9

[0099] Comparative Example 9 adjusts the proportion of the cable shielding material to 50% peanut shell-based biomass carbon black, 47% linear low density polyethylene, 1.5% antioxidant and 1.5% white oil by mass.

[0100] Comparative Example 10

[0101] Comparative Example 10 adjusts the proportion of the cable shielding material to 70% peanut shell-based biomass carbon black, 27% linear low density polyethylene, 1.5% antioxidant and 1.5% white oil by mass.

[0102] The elongation at break, tensile strength and volume resistivity of the seven cable shielding materials provided by Example 4-Example 6 and Comparative Example 7-Comparative Example 10 are measured, and the results are as follows in Table 3:

[0103] Table 3

[0104]

[0105] As can be seen from Table 3, as the content of peanut shell carbon black increases, the elongation at break of the material decreases significantly; while the tensile strength first increases and then decreases, reaching a peak when the content of carbon black is 40%, and then decreasing. From the analysis of materials science, LLDPE as a semi-crystalline thermoplastic plastic, adding a certain amount of carbon black can enhance the matrix and significantly improve the tensile strength of the composite material. However, when the content of carbon black exceeds 40%, due to the serious agglomeration of carbon black particles, a large number of interface defects are generated in the material, which in turn leads to a decrease in tensile strength. As can be seen, when the peanut shell carbon black is added in an appropriate amount in the cable shielding composite material, the strength of the material can be effectively improved, while excessive filling leads to a significant decrease in the toughness of the material due to the agglomeration effect.

[0106] The volume resistivity of the shielding material shows a clear negative correlation with the content of carbon black. In the process of gradually increasing the content of peanut shell carbon black from 30% to 40%, the volume resistivity decreases from 1×10 11 Ω·cm to 8.2×10 10 Ω·cm, and the downward trend in this stage is relatively flat. The reason is that when the content of carbon black is low, the distance between the carbon black particles is too large, making it difficult to build a stable conductive network in the polymer matrix. When the content of carbon black is further increased from 40% to 60%, the volume resistivity decreases from 8.2×10 10Ω·cm sharply dropped to about 21 Ω·cm, and the drop was 9 orders of magnitude. When the content of carbon black was more than 60%, even if it was increased to 70%, the resistivity was only reduced to about 5 Ω·cm, and the decrease rate was significantly slowed down. This shows that when the content of carbon black reaches 60%, a continuous conductive network has been formed inside the shielding material. Subsequent increase of carbon black can make the conductive network more dense, but the effect of improving the overall conductivity is no longer obvious, so the decrease rate of the volume resistivity is significantly slowed down. In summary, when the content of peanut shell carbon black reaches 60%, the volume resistivity of the shielding material meets the requirements of GB / T10738-2007 standard. Although further increasing the content of carbon black can further optimize the conductive performance, from the cost and performance improvement cost-effectiveness, the addition of 60% of carbon black is a better choice for preparing the shielding material.

[0107] According to the GB / T1040.2-2006 standard, the key mechanical property index of the cable shielding material is tensile strength ≥ 15 MPa, and elongation at break ≥ 200%. The addition of 60% of carbon black also meets the requirements of GB / T1040.2-2006 standard.

[0108] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. Peanut shell-based biomass carbon black, characterized in that... The preparation method, specifically the following steps: S1. Raw material pretreatment Waste peanut shell powder is placed in deionized water and ultrasonically cleaned to remove mud and soluble impurities attached to the surface. Then, peanut shells are mixed with 10% sodium hydroxide solution at a solid-liquid ratio of 1:

8. The mixture is stirred in a water bath at 70℃-80℃ for 3-5 hours and then rinsed with deionized water until neutral. After drying, pretreated peanut shells are obtained. S2, Primary pre-carbonization The pretreated peanut shells were pre-carbonized in a tube furnace at 350℃-450℃ for 1 hour to induce the lignin side chain to break and generate small molecule volatiles; then the temperature was raised to 750℃-850℃ and kept constant under nitrogen protection for another 3 hours to obtain pre-carbonized peanut shells. The pre-carbonized peanut shells were then ground in a planetary ball mill for 15 minutes and passed through a 100-mesh sieve to obtain charcoal powder. S3, Carbon Powder Activation The carbon powder was immersed in a 40% zinc chloride solution and stirred continuously in a 75°C constant temperature water bath for 24 hours. Then it was placed in a tube furnace for activation. The temperature was raised to 800°C at 10°C / min and held for 1 hour under a nitrogen atmosphere. Finally, it was subjected to alternating ultrasonic cleaning with deionized water and anhydrous ethanol for 15 minutes each time, repeated 3 times, to thoroughly remove residual zinc salts and pyrolysis byproducts. After cleaning, it was treated in an 80°C vacuum drying oven for 24 hours to obtain activated carbon powder. S4, secondary carbonization The activated carbon powder was placed in a tube furnace and subjected to secondary carbonization using a programmable temperature controlled tube furnace. The carrier gas was nitrogen, the gas flow rate was 300 mL / min, and the heating rate was 5℃ / min. After heating to 1300℃-1400℃, the temperature was held for 2 hours to obtain the peanut shell-based biomass carbon black.

2. The peanut shell-based biomass carbon black according to claim 1, characterized in that: The waste peanut shell powder has a particle size of <2mm and an ash content of <5%.

3. The peanut shell-based biomass carbon black according to claim 1, characterized in that: Waste peanut shell powder was ultrasonically cleaned in deionized water to remove mud and soluble impurities adhering to the surface. Then, the peanut shells were mixed with a 10% sodium hydroxide solution at a solid-liquid ratio of 1:

8. After stirring in a water bath at 75°C for 4 hours, the mixture was rinsed with deionized water until neutral and dried to obtain pretreated peanut shells.

4. The peanut shell-based biomass carbon black according to claim 1, characterized in that: The pretreated peanut shells were pre-carbonized in a tube furnace at 400°C for 1 hour to induce the lignin side chains to break and generate small volatile molecules. The temperature was then raised to 800°C and kept constant under nitrogen protection for another 3 hours to obtain pre-carbonized peanut shells. The pre-carbonized peanut shells were then ground in a planetary ball mill for 15 minutes and passed through a 100-mesh sieve to obtain carbon powder.

5. The peanut shell-based biomass carbon black according to claim 1, characterized in that: The activated carbon powder was placed in a tube furnace and subjected to secondary carbonization using a programmable temperature controlled tube furnace. The carrier gas was nitrogen, the gas flow rate was 300 mL / min, and the heating rate was 5℃ / min. After heating to 1350℃, the temperature was maintained for 2 hours to obtain the peanut shell-based biomass carbon black.

6. A cable shielding material, characterized in that: It is prepared by mass ratio of 58-60% of peanut shell-based biomass carbon black as described in any one of claims 1-5, 38-40% of linear low-density polyethylene, 1-2% of antioxidant and 1-2% of white oil.

7. A cable shielding material, characterized in that: It is prepared by mass ratio of 60% of peanut shell-based biomass carbon black as described in any one of claims 1-5, 38% of linear low-density polyethylene, 1% of antioxidant and 1% of white oil.

8. The cable shielding material according to claim 7, characterized in that: The antioxidant is a hindered phenolic stabilizer.

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