Polypropylene-based thermoplastic cable shielding material and preparation method thereof

Abstract

The invention discloses a polypropylene-based thermoplastic cable shielding material and a preparation method thereof, and the polypropylene-based thermoplastic cable shielding material comprises the following components in parts by weight: 100 parts of polypropylene resin, 10-40 parts of a modified elastomer, 2-6 parts of an amino silane functionalized carbon quantum dot compatilizer, 15-25 parts of carboxylated carbon black, 0.2-0.7 part of an antioxidant, and 0.2-2 parts of a lubricant, the modified elastomer is a mixture of a polypropylene soluble substance and a polyolefin elastomer. The modified elastomer used in the invention has good compatibility with a polypropylene matrix, and can significantly improve the toughness of the matrix and reduce physical defects of an interface; meanwhile, the amino silane functionalized carbon quantum dot compatilizer used in the invention can reduce and uniformly disperse the phase size, can also improve the dispersity of the carbon black, has conductivity and can reduce the content of the carbon black, and the cable shielding material with high conductivity and an ultra-smooth surface can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of cable materials, and particularly relates to a polypropylene-based thermoplastic cable shielding material and a preparation method thereof. Background Art

[0002] With the development of the economy and the construction of cities, a relatively large-scale power cable network has been built in China. Currently, the most commonly used insulating material for power cables is cross-linked polyethylene (XLPE). However, XLPE has high production costs, low productivity, and is difficult to recycle due to being a thermosetting material, which will cause serious environmental pollution. Currently, recyclable thermoplastic polypropylene has become a research focus due to its excellent electrical and heat resistance, which is of strategic significance for environmental protection and energy conservation. In order to apply polypropylene insulating materials, it is very important to study the matching shielding materials.

[0003] Polypropylene shielding materials usually blend polypropylene with other polyolefin elastomers to improve the flexibility and electrical properties of polypropylene, and retain the excellent thermo-mechanical properties of polypropylene. At the same time, a large amount of carbon black is added to achieve good conductivity, but there will be problems such as poor compatibility between the two phases and carbon black agglomeration, which affect conductivity and surface smoothness. Adding a large amount of carbon black will also lead to deterioration of mechanical properties and processing properties. Summary of the Invention

[0004] In view of this, the main purpose of the present invention is to provide a polypropylene-based thermoplastic cable shielding material and a preparation method thereof. This method can not only enhance the compatibility between the elastomer and the polypropylene matrix, reduce and uniformly disperse the phase size, but also improve the dispersion of carbon black and reduce the carbon black content.

[0005] To achieve the above invention purpose, the first aspect of the present invention provides a polypropylene-based thermoplastic cable shielding material, which comprises the following components in parts by weight: 100 parts of polypropylene resin, 10 - 40 parts of modified elastomer, 2 - 6 parts of amino-silane-functionalized carbon quantum dot compatibilizer, 15 - 25 parts of carboxylated carbon black, 0.2 - 0.7 part of antioxidant, and 0.2 - 2 parts of lubricant, wherein the modified elastomer is a mixture of polypropylene soluble matter and polyolefin elastomer.

[0006] Preferably, 100 parts of polypropylene resin, 20 - 30 parts of modified elastomer, 2 - 4 parts of amino-silane-functionalized carbon quantum dot compatibilizer, 20 - 25 parts of carboxylated carbon black, 0.4 - 0.5 part of antioxidant, and 0.4 - 6 parts of lubricant.

[0007] In some embodiments, the polypropylene resin is selected from random copolymer polypropylene; preferably, the soluble matter of the polypropylene resin is 5 - 30 wt%, the soluble matter IV is 1 - 5 dL / g, and the ethylene content of the soluble matter is 15 - 40 wt%.

[0008] In some embodiments, in the modified elastomer, the mass ratio of the polypropylene solubles to the polyolefin elastomer is 5:95 - 25:75. After setting this parameter, it can bring the effects of reducing the dispersed phase size, improving compatibility and toughening, and preferably 15:85 - 20:80.

[0009] In some embodiments, the polypropylene solubles are impact copolymer polypropylene, with a solubles content of 18 - 60%, and the ethylene content in the solubles is 25 - 60%; preferably, it is the solubles with a molecular weight between 30,000 - 1,000,000.

[0010] In the present invention, introducing solubles (in-situ polymerized rubber phase) into the polypropylene resin can improve the compatibility between the matrix resin and the elastomer, reduce interfacial defects, and enhance the overall performance. At the same time, the inventors of the present invention have found through research that the low molecular weight part does not have toughening ability and will also precipitate to affect the product performance, especially for cable compound products. The ultra-high molecular weight part affects the processing performance. Therefore, the present invention selects a quantitative molecular weight part, which can not only achieve the toughening effect but also have excellent processability.

[0011] In some embodiments, the polyolefin elastomer is an ethylene-propylene copolymerized propylene-based elastomer. Preferably, the Mw of the elastomer is 12 - 35×10 4 g / mol, the molecular weight distribution is 2.2 - 3.0, and the ethylene content is 8 - 18 wt%.

[0012] In some embodiments, the modified elastomer is a mixture containing polypropylene solubles and polyolefin elastomer with an acid anhydride grafted on the surface.

[0013] In some embodiments, the modified elastomer is prepared by the following method:

[0014] S1: Heat the polypropylene solubles to dissolve them in the first solvent to obtain a solution containing polypropylene solubles;

[0015] S2: Remove the solvent in the solution and dry it to obtain solubles powder;

[0016] S3: Mix the polyolefin elastomer and the second solvent with the solubles powder, heat and dissolve, then remove the second solvent and dry to obtain the modified elastomer powder.

[0017] Preferably, step S2 further includes preparing solubles with a molecular weight between 30,000 - 1,000,000 from the solubles powder through a molecular weight fractionation device.

[0018] Preferably, it further includes step S4: Graft an acid anhydride on the surface of the modified elastomer powder in step S3. The acid anhydride is selected from maleic anhydride and / or itaconic anhydride. Preferably, the acid anhydride is maleic anhydride.

[0019] In some embodiments, the modified elastomer is prepared by the following method:

[0020] S1: Heat the impact copolymer polypropylene to 130 - 150 °C and dissolve it in a solvent, then cool it to room temperature and filter the insoluble substances to obtain a solution containing polypropylene soluble substances;

[0021] S2: Rotary evaporate the solvent in the solution and dry it to obtain soluble substance powder;

[0022] S3: Prepare soluble substances with a molecular weight between 30,000 - 1,000,000 from the soluble substance powder through the molecular weight fractionation equipment of POLYMER CHAR. The solvent used for the soluble substances is trichlorobenzene;

[0023] S4: Add the propylene-based elastomer powder and trichlorobenzene solvent to the soluble substances in step S3, heat to 150 - 175 °C, stir to dissolve, then remove the solvent and dry to obtain modified elastomer powder;

[0024] S5: Under nitrogen protection, stir and mix the modified elastomer powder in step S4 with a solution of a peroxide initiator, maleic anhydride, and an interfacial agent, swell, heat for reaction, add a precipitating agent, let it stand for precipitation, wash and dry to obtain maleic anhydride-grafted elastomer.

[0025] In the present invention, the type of solvent in step S1 is not limited as long as it can dissolve polyolefins, such as xylene, trichlorobenzene, ortho-dichlorobenzene, etc.

[0026] In the present invention, the peroxide initiator in step S4 is selected from at least one of benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, or diisopropylbenzene hydroperoxide; the interfacial agent is xylene, and the precipitating agent is acetone.

[0027] In some embodiments, the amino-silane-functionalized carbon quantum dot compatibilizer is prepared by the following method:

[0028] Place an organic small molecule precursor and a silane coupling agent containing a multi-amino structure in an inert gas atmosphere, heat to 240 - 280 °C, and react for 1 - 3 min to obtain;

[0029] In some embodiments, the organic small molecule precursor includes natural substances or synthetic organic compounds, such as at least one of citric acid, cellulose, glucose, ethylenediamine, diethylenetriamine, triethylenetetramine, and preferably citric acid powder.

[0030] Preferably, the silane coupling agent with a multi-amino structure is AEAPMS.

[0031] In some embodiments, the preparation method of the modified carbon black includes the following steps:

[0032] Mix and disperse carbon black and concentrated nitric acid, and react at 100-120 °C for 16-24 hours; after the reaction is completed, cool, separate, wash with water until the filtrate is neutral, and dry.

[0033] In some embodiments, the carbon black has a particle size of 10-30 nm, an oil absorption value greater than 130 cc / 100 g, and an iodine absorption value greater than 70 g / kg; acetylene carbon black is preferred, and Cabot VXC500 and / or XC72 are more preferred.

[0034] The second aspect of the present invention provides a method for preparing a polypropylene-based thermoplastic cable shielding material, comprising the following steps:

[0035] S1. After dissolving the amino-silane functionalized carbon quantum dots, add the modified elastomer and reflux at 130-150 °C for 2-5 h, and then dry to obtain the modified elastomer carbon quantum dots;

[0036] S2. Add polypropylene resin, modified elastomer carbon quantum dots, carboxylated carbon black, antioxidant, and lubricant into a twin-screw extruder for melt blending and pelletizing, with a temperature of 195-230 °C and a rotation speed of 200-300 r / min.

[0037] The above preparation method of the present invention not only improves the dispersion uniformity of carbon black, but also improves the dispersion of the elastomer in the matrix and the interfacial compatibility of the matrix resin, and reduces the size of the dispersed phase.

[0038] In some embodiments, the modified elastomer is a modified elastomer with acid anhydride grafted on the surface.

[0039] In some embodiments, the amino-silane functionalized carbon quantum dots are dissolved in a solvent, such as xylene.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] (1) The present invention introduces solubles and elastomers into polypropylene, effectively improving the compatibility between polypropylene and elastomers, reducing interfacial defects. By introducing amino-silane functionalized carbon quantum dots as compatibilizers, not only can the interfacial compatibility of the matrix resin be further improved and the size of the dispersed phase be reduced; but also the abundant amino groups on the surface of the amino-silane functionalized carbon quantum dots can react with the carboxyl groups on the surface of the carboxylated modified carbon black to form amide bonds. On the one hand, this can greatly improve the dispersion of carbon black (which is beneficial to the two most critical properties of cable materials: high-temperature semi-conductivity and protrusions), and on the other hand, due to the excellent conductivity of carbon quantum dots, the amount of carbon black used can be further reduced (reducing mechanical loss and being beneficial to processing performance).

[0042] (2) The material prepared by the present invention has excellent electrical conductivity and mechanical properties on the one hand, and has a super-smooth surface, and on the other hand, it can be recycled and reused, showing environmental friendliness.

[0043] Other features and advantages of the present invention will be described in detail in the following specific embodiments. Specific Embodiments

[0044] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0045] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0046] The raw materials of the product and their sources are as follows:

[0047] Random copolymer polypropylene: Yanshan Petrochemical PPR4220, Mw is 690,000 g / mol, soluble matter is 6 wt%, soluble matter IV is 1.38 dL / g, and ethylene content of soluble matter is 17.1 wt%;

[0048] Random copolymer polypropylene: Formosa Plastics 5012XT, Mw is 450,000 g / mol, soluble matter is 12 wt%, soluble matter IV is 2.6 dL / g, and ethylene content of soluble matter is 28 wt%;

[0049] Impact copolymer polypropylene is Wanhua EP246R, its soluble matter content is 31%, and the ethylene content in its soluble matter is 28%;

[0050] Impact copolymer polypropylene is EP300H, its soluble matter content is 21%, and the ethylene content in its soluble matter is 38%;

[0051] Carbon black: Cabot VXC500, particle size is 20 nm, oil absorption value is 148 cc / 100 g, and iodine absorption value is 75 g / kg.

[0052] Elastomer: ExxonMobil 6202, ethylene-propylene copolymer, Mw is 160,000 g / mol, molecular weight distribution is 2.8, and ethylene content is 15 wt%;

[0053] Elastomer: ExxonMobil 6102FL, ethylene-propylene copolymer, Mw is 260,000 g / mol, molecular weight distribution is 2.8, and ethylene content is 16 wt%;

[0054] For other raw materials and reagents, if not otherwise specified, they can all be obtained through commercial channels.

[0055] The description of the product test performance is as follows:

[0056] Tensile strength and elongation at break: Using an Instron tensile tester (INSTRON 5966), the test method is in accordance with GB / T 1040.1 and GB / T 1040.2, with a thickness of 1.0 ± 0.1 mm and a tensile speed of 200 ± 20 mm / min.

[0057] Volume resistivity: Using a semi-conductive volume resistivity tester (DB-4, Shanghai Peicheng), the test method is in accordance with GBT3048.3.

[0058] The following describes in detail the polypropylene-based thermoplastic cable shielding material and its preparation method of the present invention through examples.

[0059] Example 1

[0060] The polypropylene-based thermoplastic cable shielding material comprises the following components in parts by weight: 100 parts of random copolymerized polypropylene, 20 parts of modified elastomer, wherein the ratio of the soluble matter to the polyolefin elastomer is 15:85, 2 parts of an amino-silane-functionalized carbon quantum dot compatibilizer, 25 parts of modified carbon black, 0.4 part of antioxidant, and 0.5 part of lubricant. The random copolymerized polypropylene is Yanshan Petrochemical 4220, the impact copolymerized polypropylene is EP246R, and the ethylene-propylene copolymer elastomer is ExxonMobil 6202. The modified carbon black is carboxylated Cabot VXC500, the antioxidant is 300, and the lubricant is a polyethylene wax PEW0363 and white oil Nynas 330 with a mass ratio of 1:1.

[0061] The preparation method of the modified elastomer is as follows: The impact copolymerized polypropylene is heated to 150 °C and dissolved in xylene, then cooled to room temperature and the insoluble matter is filtered to obtain a solution containing polypropylene soluble matter; the xylene in the solution is removed by rotary evaporation and dried to obtain a soluble matter powder; the soluble matter powder is prepared by a molecular weight fractionation device of POLYMER CHAR to obtain a soluble matter with a molecular weight between 100,000 and 800,000, and the solvent used is trichlorobenzene; the propylene-based elastomer powder and an appropriate amount of trichlorobenzene solvent are added to the soluble matter in the previous step, heated to 160 °C, stirred and dissolved, and then the solvent is removed and dried.

[0062] The surface of the modified elastomer powder is grafted with maleic anhydride. The preparation method is as follows: Under nitrogen protection, the modified elastomer powder, dibenzoyl peroxide, maleic anhydride, and xylene are added to a reaction kettle with mechanical stirring, and the mass ratio of the four is: 100:0.4:4:500. Heat and stir under reflux, add acetone, let it stand and cool, precipitate and filter, wash and dry to obtain maleic anhydride-grafted elastomer.

[0063] The preparation method of the amino-silane-functionalized carbon quantum dot compatibilizer is as follows: Place the silane coupling agent AEAPMS in a reaction kettle. After introducing nitrogen for about 10 minutes, raise the temperature to 260 °C. Then add anhydrous citric acid and react for 2 minutes. Then wash it three times with n-hexane to obtain the required product.

[0064] The preparation method of the carboxylated modified carbon black is as follows: Add Cabot VXC500 and concentrated nitric acid with a mass fraction concentration of 66% into a three-necked flask, and ultrasonically disperse for 30 minutes. After deoxygenation, heat and stir the reaction in an oil bath at 100 °C for 17 hours. Cool to room temperature, filter, and wash with deionized water until the filtrate is neutral. Finally, vacuum dry the precipitate obtained by filtration at 60 °C to obtain CB-COOH.

[0065] The preparation method of the polypropylene-based thermoplastic cable shielding material in this example is as follows: Dissolve the amino-silane-functionalized carbon quantum dot in xylene, then add maleic anhydride-grafted elastomer and reflux at 140 °C for 3 hours, and then dry to obtain the modified elastomer carbon quantum dot; Add polypropylene, modified elastomer carbon quantum dot, modified carbon black, antioxidant, and lubricant into a twin-screw extruder for melt blending and pelletizing. The temperature is 200 - 230 °C, and the rotation speed is 250 r / min.

[0066] Example 2

[0067] The polypropylene-based thermoplastic cable shielding material contains the following components in parts by weight: 100 parts of random copolymer polypropylene, 30 parts of modified elastomer, in which the ratio of the soluble matter to the polyolefin elastomer is 10:90, 2 parts of amino-silane-functionalized carbon quantum dot compatibilizer, 20 parts of modified carbon black, 0.5 part of antioxidant, and 0.4 part of lubricant. The random copolymer polypropylene is Yanshan Petrochemical 4220, the impact copolymer polypropylene is EP246R, and the ethylene-propylene copolymer elastomer used is ExxonMobil 6102FL. The modified carbon black is carboxylated Cabot VXC500, the antioxidant is 300, and the lubricant is a polyethylene wax PEW0363 and white oil Nynas 330 with a mass ratio of 1:1.

[0068] Refer to the method of Example 1 to prepare the polypropylene-based thermoplastic cable shielding material.

[0069] Example 3

[0070] Polypropylene-based thermoplastic cable shielding material, comprising the following components in parts by weight: 100 parts of random copolymerized polypropylene, 25 parts of modified elastomer, wherein the proportion of soluble matter to polyolefin elastomer is 20:80, 4 parts of amino-silane functionalized carbon quantum dot compatibilizer, 25 parts of modified carbon black, 0.5 part of antioxidant, and 0.6 part of lubricant. The random copolymerized polypropylene is Formosa Plastics 5012XT, the impact copolymer polypropylene is EP300H, and the ethylene-propylene copolymer elastomer is ExxonMobil 6102FL. The modified carbon black is carboxylated Cabot VXC500, the antioxidant is 300, and the lubricant is polyethylene wax PEW0363 and white oil Nynas 330 with a mass ratio of 1:1.

[0071] Prepare the polypropylene-based thermoplastic cable shielding material according to the method of Example 1.

[0072] Example 4

[0073] Refer to the method of Example 3, the difference is: after obtaining the polypropylene soluble matter, no treatment is carried out, that is, the preparation method of the modified elastomer is: heat the impact copolymer polypropylene to 150 °C and dissolve it in xylene, then cool to room temperature and filter the insoluble matter to obtain a solution containing polypropylene soluble matter; rotary evaporate the xylene in the solution and dry it to obtain the soluble matter powder.

[0074] Comparative Example 1

[0075] Refer to the method of Example 1, the difference is: this method does not use a compatibilizer, and the remaining formula and preparation method are the same.

[0076] Comparative Example 2

[0077] Refer to the method of Example 2, the difference is: the surface of the modified elastomer powder in this method is not grafted with maleic anhydride, and the remaining formula and preparation method are the same.

[0078] Comparative Example 3

[0079] Refer to the method of Example 3, the difference is: the carbon black used in this method is ordinary carbon black Cabot VXC500 without carboxylation treatment, and the remaining formula and preparation method are the same.

[0080] The performance test results of the above examples and comparative examples are shown in Table 1.

[0081] Table 1 Performance Test Results

[0082]

[0083] As can be seen from the data in Table 1, when comparing Examples 1-4 with Comparative Examples 1-3, Examples 1-3 have excellent mechanical properties and conductive effects due to the good compatibility between the matrix resins and the good dispersion of carbon black. In Example 4, the molecular weight fractionation treatment was not carried out on the obtained soluble polypropylene, which mainly had some effects on the mechanical properties. In Comparative Example 1, no compatibilizer was used, resulting in poor dispersion and easy agglomeration of carbon black, and phase separation was prone to occur in the matrix resin, making it difficult to form a conductive path. In Comparative Example 2, maleic anhydride was not grafted on the surface of the elastomer, and the compatibility between polypropylene and the elastomer was poor, resulting in a certain loss of mechanical properties. In Comparative Example 3, the carbon black was not carboxylated and modified, and the dispersion was poor, which had a greater impact on the conductive performance. In summary, Comparative Examples 1-3 are inferior to Examples in terms of mechanical and conductive effects.

[0084] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation manners here. All obvious changes or modifications derived from the technical solutions of the present invention are within the spirit scope covered by the present invention.

Claims

1. A polypropylene-based thermoplastic cable shielding material, characterized in that, It comprises the following components in parts by weight: 100 parts of polypropylene resin, 10 - 40 parts of modified elastomer, 2 - 6 parts of amino - silane functionalized carbon quantum dot compatibilizer, 15 - 25 parts of carboxylated carbon black, 0.2 - 0.7 part of antioxidant, and 0.2 - 2 parts of lubricant, wherein the modified elastomer is a mixture of polypropylene soluble matter and polyolefin elastomer.

2. The cable shielding material according to claim 1, characterized in that, The polypropylene resin is selected from random copolymer polypropylene; preferably, the soluble matter in the polypropylene resin is 5 - 30 wt%, the soluble matter IV is 1 - 5 dL / g, and the ethylene content of the soluble matter is 15 - 40 wt%.

3. The cable shielding material according to claim 1 or 2, characterized in that In the modified elastomer, the mass ratio of polypropylene soluble matter to polyolefin elastomer is 5:95 - 25:75, preferably 15:85 - 20:80; Preferably, the polypropylene soluble matter is impact copolymer polypropylene, its soluble matter content is 18 - 60 wt%, and the ethylene content in its soluble matter is 25 - 60 wt%; more preferably, its soluble matter is the soluble matter with a molecular weight between 30,000 - 1,000,000; and / or, The polyolefin elastomer is an ethylene-propylene copolymerized propylene-based elastomer. Preferably, the Mw of the elastomer is 12 - 35 * 10 4 g / mol, the molecular weight distribution is 2.2 - 3.0, and the ethylene content is 8 - 18 wt%; The modified elastomer is a mixture of polypropylene soluble matter and polyolefin elastomer grafted with anhydride on the surface.

4. The cable shielding material according to any one of claims 1 to 3, characterized in that The modified elastomer is prepared by the following method: S1: Heat up and dissolve the polypropylene soluble matter in the first solvent to obtain a solution containing the polypropylene soluble matter; S2: Remove the first solvent in the solution and dry it to obtain soluble matter powder; S3: Mix the polyolefin elastomer and the second solvent with the soluble matter powder, heat up and dissolve it, then remove the second solvent and dry it to obtain modified elastomer powder; Preferably, step S2 further includes preparing the soluble matter with a molecular weight between 30,000 - 1,000,000 from the soluble matter powder through a molecular weight fractionation device.

5. The cable shielding material according to claim 4, characterized in that, It further includes step S4: Graft anhydride on the surface of the modified elastomer powder in step S3, and the anhydride is selected from maleic anhydride and / or itaconic anhydride. Preferably, the anhydride is maleic anhydride.

6. The cable shielding material according to claim 5, characterized in that, The modified elastomer is prepared by the following method: S1: Heat up the impact copolymer polypropylene to 130 - 150 °C and dissolve it in the solvent, then cool it to room temperature and filter out the insoluble matter to obtain a solution containing the polypropylene soluble matter; S2: Rotary evaporate and remove the solvent in the solution and dry it to obtain soluble matter powder; S3: Prepare the soluble matter with a molecular weight between 30,000 - 1,000,000 from the soluble matter powder through a molecular weight fractionation device, and the solvent used for the soluble matter is trichlorobenzene; S4: Add the propylene - based elastomer powder and trichlorobenzene solvent to the soluble matter in step S3, heat up to 150 - 175 °C, stir and dissolve it, then remove the solvent and dry it to obtain modified elastomer powder; S5: Under nitrogen protection, stir - mix, swell, and heat - react the modified elastomer powder in step S4 with a solution containing a peroxide initiator, maleic anhydride, and an interfacial agent, add a precipitating agent, let it stand for precipitation, wash and dry to obtain maleic anhydride - g - elastomer.

7. The cable shielding material according to any one of claims 1 - 6, wherein The amino - silane functionalized carbon quantum dot compatibilizer is prepared by the following method: It is prepared by heating an organic small molecule precursor and a silane coupling agent containing a polyamino structure to 240 - 280 °C in an inert gas atmosphere and reacting for 1 - 3 min; Preferably, the organic small molecule precursor is selected from at least one of citric acid, cellulose, glucose, ethylenediamine, diethylenetriamine, triethylenetetramine, and preferably citric acid powder; Preferably, the silane coupling agent with a polyamino structure is AEAPMS.

8. The cable shielding material according to any one of claims 1 - 7, characterized in that The preparation method of the carboxylated carbon black comprises the following steps: Mix and disperse carbon black and concentrated nitric acid, and react at 100 - 120 °C for 16 - 24 hours; after the reaction is completed, cool, separate, wash with water until the filtrate is neutral, and dry; The particle size of the carbon black is 10 - 30 nm, the oil absorption value is greater than 130 cc / 100 g, and the iodine absorption value is greater than 70 g / kg; preferably acetylene carbon black, more preferably Cabot VXC500 and / or XC72.

9. A method for preparing the polypropylene-based thermoplastic cable shielding material according to any one of claims 1-8, characterized in that, Comprises the following steps: S1. After dissolving the amino - silane - functionalized carbon quantum dots, add a modified elastomer and reflux at 130 - 150 °C for 2 - 5 h, and then dry to obtain modified elastomer carbon quantum dots; S2. Add polypropylene resin, modified elastomer carbon quantum dots, carboxylated carbon black, antioxidant, and lubricant into a twin - screw extruder for melt - blending and pelletizing, with the temperature at 195 - 230 °C and the rotation speed at 200 - 300 r / min.

10. The preparation method of the cable shielding material according to claim 9, wherein, The modified elastomer is a modified elastomer with an acid anhydride grafted on the surface, and the acid anhydride is selected from maleic anhydride and / or itaconic anhydride. Preferably, the acid anhydride is maleic anhydride.

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