Polypropylene composite filler based on electrocatalytic oxidation coal gasification fine slag as raw material and preparation method thereof

Abstract

The invention discloses a preparation method of a polypropylene composite filler based on electrocatalytic oxidation coal gasification fine slag as a raw material, the preparation method comprises the steps of raw material treatment, system modification, material electrolytic oxidation and material post-treatment, the polypropylene composite filler comprises polypropylene resin and the polypropylene composite filler, based on the total weight of the composite material, the usage amount of the composite filler is 5-20wt%, and the usage amount of the composite filler is 5-20wt%. The raw materials comprise an environment-friendly functional auxiliary agent accounting for 0.5-5% of the total weight of the composite material, and the functional auxiliary agent is selected from one of a weather-proof agent, a halogen-free flame retardant and a bio-based antibacterial agent. The method has the advantages that the low-temperature plasma pretreatment and the composite modifier assisted electrocatalytic oxidation process are combined, a large number of active sites can be quickly and efficiently introduced on the surface of the coal gasification fine slag through the low-temperature plasma treatment, and the surface energy and the reaction activity of the coal gasification fine slag are remarkably enhanced.

Description

Technical Field

[0001] This invention relates to the field of polymer composite material preparation technology, specifically to a polypropylene composite filler based on electrocatalytic oxidation coal gasification fine slag as raw material and its preparation method. Background Technology

[0002] my country's energy structure is dominated by coal, and coal gasification technology plays a key role in the clean utilization of coal. However, the annual emissions of coal gasification slag exceed 33 million tons, with a huge historical stockpile, posing a continuous pressure on the environment and land resources. Coal gasification slag is rich in inorganic components such as SiO2, Al2O3, Fe2O3, and CaO, as well as unburned carbon residue. Theoretically, it has resource potential in building materials, environmental remediation, and functional fillers. Polypropylene, as a general-purpose plastic with excellent comprehensive performance, is limited in its application due to deficiencies in low-temperature brittleness, heat resistance, and electrical properties. Developing cost-effective fillers that can simultaneously enhance the mechanical properties of polypropylene and endow it with specific functions has significant market value. Therefore, we propose a polypropylene composite filler based on electrocatalytic oxidation of coal gasification slag as raw material and its preparation method. Summary of the Invention

[0003] The purpose of this invention is to provide a polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material and its preparation method.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material, comprising raw material processing, system modification, material electrolytic oxidation, and material post-treatment. The steps of the polypropylene composite packing material preparation method are as follows: Step 1: Dry the coal gasification fine slag and treat it with low-temperature plasma to activate its surface; Step 2: Disperse the fine residue from Step 1 in a sulfuric acid solution, add a composite modifier to the system, and obtain a suspension; Step 3: Perform segmented dynamic current electrolytic oxidation on the suspension obtained in Step 2; Step 4: Centrifuge, wash and dry the product after electrolysis in Step 3 to obtain the polypropylene composite filler.

[0005] As a further aspect of the present invention: In step one, the original coal gasification fine slag is dried at 80°C for 12-24 hours to remove free water and some bound water. Then, the dried fine slag is placed in a low-temperature plasma treatment device. The power of the low-temperature plasma treatment is 100W-500W, the treatment time is 5min-30min, and the treatment atmosphere is air.

[0006] As a further aspect of the present invention: In step two, the composite modifier includes ferric sulfate, a coupling agent, and lignin sulfonate; the concentration of the sulfuric acid solution is 0.5M-1.5M; the solid mass fraction of the fine slag is 150g / L-250g / L; the concentration of ferric sulfate in the system is 0.05M-0.15M; and Fe... 3+ / Fe 2+ During electrolysis, the redox couple can efficiently catalyze the generation of strong oxidizing species such as hydroxyl radicals. The coupling agent is a silane coupling agent or a titanate coupling agent, and its addition amount is 0.5%-3% of the dry weight of the fine residue. One end of the coupling agent can react with the hydroxyl groups on the surface of the fine residue to form a chemical bond, and the other end can interact with the polypropylene matrix or the interface layer formed subsequently. The addition amount of lignin sulfonate is 1%-5% of the dry weight of the fine residue. It prevents the particles from agglomerating during electrolysis through the steric hindrance effect, and its own phenolic hydroxyl groups and sulfonic acid groups can participate in the interface reaction.

[0007] As a further aspect of the present invention: in step three, the segmented dynamic current electrolysis includes a first stage electrolysis performed at a first current density and a first stirring rate, and a second stage electrolysis performed at a second current density higher than the first current density and a second stirring rate higher than the first stirring rate.

[0008] As a further aspect of the present invention: in step three, the current density of the first stage of electrolysis is 0.05 A / cm². 2 -0.15A / cm 2 The stirring rate was 300-500 r / min, and the electrolysis time was 0.5-1 h. Utilizing the active oxygen species generated by electrocatalysis, the electrolytically generated oxygen preferentially reacts with the active sites pretreated by plasma, promoting the initial and uniform anchoring of coupling agents and lignin sulfonate molecules onto the filler surface. The current density of the second-stage electrolysis was 0.15 A / cm². 2 -0.25A / cm 2 The stirring rate is 600r / min-800r / min, the electrolysis time is 1h-1.5h, and the enhanced current density promotes a more vigorous electrocatalytic oxidation reaction, which enables the initially grafted organic molecules to undergo partial cross-linking or further reaction, and builds a denser and stronger organic interface layer on the filler surface.

[0009] As a further embodiment of the present invention: In step four, the centrifugation speed is 4000 r / min-6000 r / min, the centrifugation time is 5 min-15 min, the washing is repeated with deionized water for centrifugation and washing 3-5 times until neutral, the drying temperature is 70℃-90℃, the drying time is 12 h-18 h, after drying, the material is ground and passed through a 400 mesh sieve to obtain polypropylene composite filler.

[0010] The polypropylene composite packing material is based on electrocatalytic oxidation coal gasification fine slag as raw material. The polypropylene composite packing material includes polypropylene resin and polypropylene composite packing material. The amount of the composite packing material is 5wt%-20wt% based on the total weight of the composite material.

[0011] As a further aspect of the present invention: the raw materials include environmentally friendly functional additives accounting for 0.5%-5% of the total weight of the composite material, wherein the functional additives are selected from weathering agents, halogen-free flame retardants and bio-based antibacterial agents.

[0012] As a further aspect of the present invention: in the polypropylene composite material, the amount of composite filler is 10wt%-15wt%.

[0013] Compared with the prior art, the beneficial effects of the present invention by adopting the above technical solution are as follows: 1. This invention combines low-temperature plasma pretreatment with an electrocatalytic oxidation process assisted by a composite modifier. The low-temperature plasma treatment can rapidly and efficiently introduce a large number of active sites on the surface of coal gasification fine slag, significantly enhancing its surface energy and reactivity. In the subsequent electrocatalytic oxidation process, the composite modifier can chemically react with the active sites to construct a strong and dense organic interface layer on the surface of the filler. This interface layer not only effectively improves the wettability and adhesion between the filler and the polypropylene matrix, but also significantly enhances the interfacial bonding strength through chemical bonding, thereby solving the technical problem of poor compatibility between traditional inorganic fillers and polypropylene, which easily leads to a decline in the mechanical properties of the material. 2. This invention achieves refined management of the electrolytic oxidation process through a segmented dynamic current electrolysis mode and matched with differentiated stirring rates. In the first stage, a relatively mild current density and stirring conditions are adopted, which is conducive to the full and uniform reaction between the active oxygen species generated by electrocatalysis and the active sites of plasma pretreatment. This promotes the initial and stable anchoring of coupling agents and lignin sulfonate molecules on the filler surface. In the second stage, by increasing the current density and stirring rate, a more vigorous electrocatalytic oxidation reaction is promoted, causing the initially grafted organic molecules to undergo partial cross-linking or further reaction. This results in the construction of a denser and stronger organic interface layer on the filler surface. This not only effectively avoids the energy waste and local overheating problems caused by a single high-intensity current, but also significantly improves the reaction efficiency and the uniformity of interface modification. 3. This invention, by introducing small amounts of different types of environmentally friendly functional additives, can conveniently prepare polypropylene composite materials with specific functions such as weather resistance, flame retardancy, or antibacterial properties, greatly expanding its application scenarios in the automotive, home appliance, construction, and packaging fields. By selecting lignin sulfonate as a green dispersant and interface reinforcing agent, it not only effectively prevents particle agglomeration during electrolysis, but its own active groups can also participate in interface reactions, enhancing the interface layer structure. This achieves the synergistic high-value utilization of coal gasification slag and agricultural waste, while reducing the use of traditional chemical dispersants, lowering production costs and environmental impact. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating the preparation process of the polypropylene composite filler in an embodiment of the present invention; Figure 2 This is a finished product image of the polypropylene composite filler in an embodiment of the present invention. Detailed Implementation

[0015] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0016] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0017] Please see the appendix Figure 1 This invention relates to a method for preparing polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material, including raw material processing, system modification, material electrolytic oxidation, and material post-treatment. The steps of the polypropylene composite packing material preparation method are as follows: Step 1: Dry the coal gasification fine slag and treat it with low-temperature plasma to activate its surface; Step 2: Disperse the fine residue from Step 1 in a sulfuric acid solution, add a composite modifier to the system, and obtain a suspension; Step 3: Perform segmented dynamic current electrolytic oxidation on the suspension obtained in Step 2; Step 4: Centrifuge, wash and dry the product after electrolysis in Step 3 to obtain polypropylene composite filler.

[0018] In one embodiment of the present invention: in step one, the original coal gasification fine slag is dried at 80°C for 12-24 hours to remove free water and some bound water. Then the dried fine slag is placed in a low-temperature plasma treatment device. The power of the low-temperature plasma treatment is 100W-500W, the treatment time is 5min-30min, and the treatment atmosphere is air.

[0019] In one embodiment of the present invention: In step two, the composite modifier includes ferric sulfate, a coupling agent, and lignin sulfonate; the concentration of the sulfuric acid solution is 0.5M-1.5M; the solid mass fraction of the fine slag is 150g / L-250g / L; the concentration of ferric sulfate in the system is 0.05M-0.15M; Fe 3+ / Fe 2+ During electrolysis, the redox couple can efficiently catalyze the generation of strong oxidizing species such as hydroxyl radicals. The coupling agent is a silane coupling agent or a titanate coupling agent, and its addition amount is 0.5%-3% of the dry weight of the fine residue. One end of the coupling agent can react with the hydroxyl groups on the surface of the fine residue to form a chemical bond, and the other end can interact with the polypropylene matrix or the interface layer formed subsequently. The addition amount of lignin sulfonate is 1%-5% of the dry weight of the fine residue. It prevents the particles from agglomerating during electrolysis through the steric hindrance effect, and its own phenolic hydroxyl groups and sulfonic acid groups can participate in the interface reaction.

[0020] In one embodiment of the present invention: in step three, segmented dynamic current electrolysis includes a first stage of electrolysis performed at a first current density and a first stirring rate, and a second stage of electrolysis performed at a second current density higher than the first current density and a second stirring rate higher than the first stirring rate.

[0021] In one embodiment of the present invention: in step three, the current density of the first stage of electrolysis is 0.05 A / cm². 2 -0.15A / cm 2 The stirring rate was 300-500 r / min, and the electrolysis time was 0.5-1 h. Utilizing the active oxygen species generated by electrocatalysis, the electrolytically generated oxygen preferentially reacts with the active sites pretreated by plasma, promoting the initial and uniform anchoring of coupling agents and lignin sulfonate molecules onto the filler surface. The current density of the second-stage electrolysis was 0.15 A / cm². 2 -0.25A / cm 2 The stirring rate is 600r / min-800r / min, the electrolysis time is 1h-1.5h, and the enhanced current density promotes a more vigorous electrocatalytic oxidation reaction, which enables the initially grafted organic molecules to undergo partial cross-linking or further reaction, and builds a denser and stronger organic interface layer on the filler surface.

[0022] In one embodiment of the present invention: In step four, the centrifugation speed is 4000 r / min-6000 r / min, the centrifugation time is 5 min-15 min, the washing is repeated with deionized water by centrifugation 3-5 times until neutral, the drying temperature is 70℃-90℃, the drying time is 12 h-18 h, after drying, the material is ground and passed through a 400 mesh sieve to obtain the polypropylene composite packing, as shown in the attached figure. Figure 2 As shown.

[0023] Polypropylene composite filler based on electrocatalytic oxidation coal gasification fine slag as raw material, the polypropylene composite filler includes polypropylene resin and polypropylene composite filler, and the amount of composite filler is 5wt%-20wt% based on the total weight of the composite material.

[0024] The present invention will be further described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0025] Experimental materials: Coal gasification fine residue: taken from Anhui Jinmei Zhongneng Chemical Co., Ltd., its industrial analysis is shown in Table 1; Polypropylene (PP): T30S, general grade, Sinopec; Chemical reagents: sulfuric acid, ferric sulfate heptahydrate, silane coupling agent KH-550, sodium lignosulfonate, antioxidant 1010, calcium stearate, maleic anhydride-grafted polypropylene (PP-g-MAH, grafting rate 0.8-1.0%), and ammonium polyphosphate (APP, degree of polymerization >1000), all of which are analytical grade or industrial grade. Main equipment: forced-air drying oven, low-temperature plasma surface treatment instrument (DT-03 type, Institute of Microelectronics, Chinese Academy of Sciences), digital display mechanical stirrer, DC regulated power supply, custom electrolytic cell (titanium-coated ruthenium-iridium anode, stainless steel cathode), high-speed centrifuge, twin-screw extruder (SHJ-20 type) and injection molding machine; Table 1

[0026] Example 1 (1) Preparation of composite fillers: Take 1.0 kg of original gasification fine residue, spread it evenly on a tray, and dry it in an 80℃ forced-air drying oven for 24 hours; The dried fine slag was evenly spread on the sample tray of the plasma treatment equipment. The parameters were set as follows: air atmosphere, power 300W, treatment time 10min. After treatment, the color of the fine slag was slightly lighter and the fluidity was enhanced. Accurately weigh 100.0g of the plasma-treated fine slag and place it in a 1L beaker. Add 500mL of the pre-prepared 1M sulfuric acid solution, turn on the mechanical stirrer at a speed of 300r / min, and stir for 30min to ensure thorough dispersion. Add 6.95g Fe2(SO4)3·7H2O to the suspension sequentially (to make Fe... 3+ Add approximately 0.1M concentration), 1.5g KH-550 (1.5% of the dry weight of the fine residue), and 3.0g sodium lignosulfonate (3% of the dry weight of the fine residue). Continue stirring for 60 minutes to ensure that all components are mixed evenly. Transfer the well-mixed suspension to the electrolytic cell, install the electrodes, connect the DC power supply and stirrer, and start the program: First stage, set the current density to 0.1 A / cm³. 2 The stirring rate was 400 r / min, the electrolysis time was 60 min, and in the second stage, the current density was immediately adjusted to 0.2 A / cm². 2 The stirring rate was increased to 700 r / min and the electrolysis time was 60 min. During the electrolysis process, the color of the suspension gradually darkened and weak bubbles were generated. After electrolysis, transfer all the slurry to centrifuge tubes and centrifuge at 5000 r / min for 10 min. Carefully discard the light yellow supernatant, add an equal amount of deionized water, stir with a glass rod to redisperse the precipitate, centrifuge again, and repeat this washing operation a total of 4 times. Use pH test paper to test the pH of the last washing water, which is approximately 7. Transfer the washed filter cake to a petri dish and dry it in an 80°C oven for 12 hours. The dried lumpy material was placed in a mortar and gently ground, and then passed through a 400-mesh standard sieve to obtain a gray-black, free-flowing powdered composite filler, denoted as filler A; (2) Preparation and performance testing of composite materials: Prepare the raw materials according to the following weight ratio: 88.0 parts of polypropylene granules, 0.0 parts of composite filler A, 0.3 parts of antioxidant 1010, 0.2 parts of calcium stearate, and 1.5 parts of PP-g-MAH; Pour all ingredients into a high-speed mixer and mix for 5 minutes; The mixed material is poured into the feeding hopper of a twin-screw extruder. The temperatures of each section of the extruder (from the feeding section to the die head) are set as follows: 180℃, 190℃, 200℃, 205℃, and 210℃. The main engine speed is 200r / min. After melting, the material undergoes extrusion, water cooling, traction, and pelletizing to obtain composite material particles. After drying the granules at 80°C for 4 hours, they were injected into standard ASTM tensile test specimens and UL-94 flammability test specimens using an injection molding machine at a barrel temperature of 190°C-220°C and a mold temperature of 60°C. According to GB / T1040.2-2006 standard, tensile strength was tested at a speed of 50 mm / min on a universal tensile testing machine, and the vertical flammability rating of a 1.6 mm thick specimen was tested according to UL-94 standard. Test results: Tensile strength is 28.5 MPa, UL-94 rating is V-2 (no flame retardant added, equivalent to pure PP). Example 2 (1) Preparation of composite fillers: Take 1.0 kg of original gasification fine residue, spread it evenly on a tray, and dry it in an 80℃ forced-air drying oven for 24 hours; The dried fine slag was evenly spread on the sample tray of the plasma treatment equipment. The parameters were set as follows: air atmosphere, power 300W, treatment time 10min. After treatment, the color of the fine slag was slightly lighter and the fluidity was enhanced. Accurately weigh 100.0g of the plasma-treated fine slag and place it in a 1L beaker. Add 500mL of the pre-prepared 1M sulfuric acid solution, turn on the mechanical stirrer at a speed of 300r / min, and stir for 30min to ensure thorough dispersion. Add 6.95g Fe2(SO4)3·7H2O to the suspension sequentially (to make Fe... 3+ Add approximately 0.1M concentration), 1.5g KH-550 (1.5% of the dry weight of the fine residue), and 3.0g sodium lignosulfonate (3% of the dry weight of the fine residue). Continue stirring for 60 minutes to ensure that all components are mixed evenly. Transfer the well-mixed suspension to the electrolytic cell, install the electrodes, connect the DC power supply and stirrer, and start the program: First stage, set the current density to 0.1 A / cm³. 2 The stirring rate was 400 r / min, the electrolysis time was 60 min, and in the second stage, the current density was immediately adjusted to 0.2 A / cm². 2 The stirring rate was increased to 700 r / min and the electrolysis time was 60 min. During the electrolysis process, the color of the suspension gradually darkened and weak bubbles were generated. After electrolysis, transfer all the slurry to centrifuge tubes and centrifuge at 5000 r / min for 10 min. Carefully discard the light yellow supernatant, add an equal amount of deionized water, stir with a glass rod to redisperse the precipitate, centrifuge again, and repeat this washing operation a total of 4 times. Use pH test paper to test the pH of the last washing water, which is approximately 7. Transfer the washed filter cake to a petri dish and dry it in an 80°C oven for 12 hours. The dried lumpy material was placed in a mortar and gently ground, and then passed through a 400-mesh standard sieve to obtain a gray-black, free-flowing powdered composite filler, which is designated as filler B. (2) Preparation and performance testing of composite materials: Prepare the raw materials according to the following weight ratio: 80.7 parts polypropylene granules, 15.0 parts composite filler B, 3.0 parts ammonium polyphosphate (APP), 0.3 parts antioxidant 10100, and 1.0 part calcium stearate; Pour all ingredients into a high-speed mixer and mix for 5 minutes; The mixed material is poured into the feeding hopper of a twin-screw extruder. The temperatures of each section of the extruder (from the feeding section to the die head) are set as follows: 180℃, 190℃, 200℃, 205℃, and 210℃. The main engine speed is 200r / min. After melting, the material undergoes extrusion, water cooling, traction, and pelletizing to obtain composite material particles. After drying the granules at 80°C for 4 hours, they were injected into standard ASTM tensile test specimens and UL-94 flammability test specimens using an injection molding machine at a barrel temperature of 190°C-220°C and a mold temperature of 60°C. Test results: The tensile strength was 26.8 MPa, and the UL-94 rating reached V-0. This indicates that the composite filler prepared in this invention has a good synergistic effect with the halogen-free flame retardant. It can maintain good mechanical properties and achieve excellent flame retardant effect even at a high filling amount. Comparative Example 1 Using untreated raw gasification slag, at a loading rate of 10 wt%, it is mixed with polypropylene and the same type of additives (but without PP-g-MAH), and the processing technology is the same as in Example 1. Test results: The tensile strength was only 12.0 MPa, and the UL-94 rating was V-2. This indicates that the unmodified fine slag has extremely poor compatibility with PP, which seriously degrades the mechanical properties of the material. Comparative Example 2 Commercially available 800-mesh heavy calcium carbonate powder was used, and mixed with polypropylene and the same type of additives at a filling amount of 10 wt%. The processing technology was the same as in Example 1. Test results: The tensile strength was 11.4 MPa and the UL-94 rating was V-2. This indicates that conventional fillers have limited reinforcing effect under the formulation and process of this experiment, and are far inferior to the composite fillers prepared by this invention. Performance Tests and Results: Tensile strength testing was conducted according to GB / T1040.2-2006, with a testing speed of 50 mm / min. Flame retardant performance is rated according to UL-94 vertical flammability rating: The test results are shown in Table 2: Table 2

[0027] As shown in Table 2, the composite material prepared in Example 1 of this invention has a tensile strength of up to 28.5 MPa, which is much higher than that of the comparative example using unmodified fine slag and heavy calcium carbonate powder, and even nearly 50% higher than that of pure polypropylene matrix. This fully demonstrates the excellent effect of this invention in terms of interface modification and mechanical reinforcement. Example 2 achieves excellent flame retardant performance of UL-94V-0 level while maintaining high tensile strength, demonstrating the flexibility of this invention in functional applications.

[0028] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit the present invention. Those skilled in the art can make appropriate adjustments to the process parameters, types and amounts of additives under the guidance of the principles of the present invention, and such adjustments should be considered to fall within the protection scope of the present invention.

[0029] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material, comprising raw material processing, system modification, material electrolytic oxidation, and material post-treatment, characterized in that: The steps for preparing the polypropylene composite filler are as follows: Step 1: Dry the coal gasification fine slag and treat it with low-temperature plasma to activate its surface; Step 2: Disperse the fine residue from Step 1 in a sulfuric acid solution, add a composite modifier to the system, and obtain a suspension; Step 3: Perform segmented dynamic current electrolytic oxidation on the suspension obtained in Step 2; Step 4: Centrifuge, wash and dry the product after electrolysis in Step 3 to obtain the polypropylene composite filler.

2. The method for preparing polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material according to claim 1, characterized in that: In step one, the power of the low-temperature plasma treatment is 100W-500W, the treatment time is 5min-30min, and the treatment atmosphere is air.

3. The method for preparing polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material according to claim 2, characterized in that: In step two, the composite modifier includes ferric sulfate, a coupling agent, and lignin sulfonate. The concentration of the sulfuric acid solution is 0.5M-1.5M, the solid mass fraction of the fine slag is 150g / L-250g / L, the concentration of ferric sulfate in the system is 0.05M-0.15M, the coupling agent is a silane coupling agent or a titanate coupling agent, and its addition amount is 0.5%-3% of the dry basis mass of the fine slag. The addition amount of lignin sulfonate is 1%-5% of the dry basis mass of the fine slag.

4. The method for preparing polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material according to claim 3, characterized in that: In step three, the segmented dynamic current electrolysis includes a first stage of electrolysis performed at a first current density and a first stirring rate, and a second stage of electrolysis performed at a second current density higher than the first current density and a second stirring rate higher than the first stirring rate.

5. The method for preparing polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material according to claim 4, characterized in that: In step three, the current density of the first stage of electrolysis is 0.05 A / cm². 2 -0.15A / cm 2 The stirring rate was 300 r / min-500 r / min, the electrolysis time was 0.5 h-1 h, and the current density of the second stage of electrolysis was 0.15 A / cm². 2 -0.25A / cm 2 The stirring rate is 600 r / min-800 r / min, and the electrolysis time is 1 h-1.5 h.

6. The method for preparing polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material according to claim 5, characterized in that: In step four, the centrifugation speed is 4000r / min-6000r / min, the centrifugation time is 5min-15min, the washing is repeated with deionized water for 3-5 centrifugations until neutral, the drying temperature is 70-90℃, and the drying time is 12h-18h.

7. The polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material according to any one of claims 1-6, characterized in that: The polypropylene composite filler includes polypropylene resin and polypropylene composite filler, and the amount of the composite filler is 5wt%-20wt% based on the total weight of the composite material.

8. The polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material according to claim 7, characterized in that: The raw materials include environmentally friendly functional additives accounting for 0.5%-5% of the total weight of the composite material. The functional additives are selected from weathering agents, halogen-free flame retardants, and bio-based antibacterial agents.

9. The polypropylene composite packing material based on electrocatalytic oxidation coal gasification fine slag as raw material according to claim 8, characterized in that: In the polypropylene composite material, the amount of composite filler is 10wt%-15wt%.

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