High wear-resistant phenolic plastic for gas meter valve grid valve cover and preparation method thereof

Abstract

The application provides a high-wear-resistance phenolic plastic for a gas meter valve grid valve cover and a preparation method thereof. The plastic is composed of the following components in parts by weight: phenolic resin 60-85 parts, spherical graphite 10-25 parts, needle-shaped petroleum coke 10-20 parts, composite wear-resistant agent 7-20 parts, bifunctional coupling agent 2-5 parts, carboxyl-terminated butylnitrile rubber 3-8 parts, curing agent 8-15 parts, and curing accelerator 1-3 parts. The composite wear-resistant agent comprises polytetrafluoroethylene micro powder 3-8 parts, nano silicon carbide 2-6 parts, and calcium stearate 2-6 parts. The spherical graphite is easy to roll on the friction interface and forms a continuous lubricating film. The needle-shaped petroleum coke is oriented and arranged along the shearing direction in kneading and injection molding flow, forming a three-dimensional skeleton. The needle-shaped particles of the petroleum coke are inserted between the spherical graphite, preventing the graphite from being excessively compacted under pressure and losing the lubricating function, and simultaneously inhibiting the resin curing shrinkage and water absorption expansion. The composite wear-resistant agent is composed of the polytetrafluoroethylene micro powder, the nano silicon carbide, and the calcium stearate, forming a "soft-hard-assist" synergistic system.

Description

Technical Field

[0001] This invention relates to the field of phenolic plastics technology, and in particular to a high wear-resistant phenolic plastic for gas meter valve grille cover and its preparation method. Background Technology

[0002] Diaphragm gas meters are widely used gas metering instruments due to their compact structure, reliable metering, and economical price. Their core working principle lies in the regular reciprocating sliding of the valve cover on the valve grille (also called the valve seat) to control the direction of airflow, driving the diaphragm to move and ultimately achieving metering. Therefore, the fit between the valve cover and the valve grille directly affects the sealing effect and metering accuracy of the metering chamber.

[0003] Currently, valve grilles and covers are commonly made of phenolic resin using a molding process. To reduce the coefficient of friction, graphite is often added to the phenolic resin as a solid lubricant. However, existing technologies have the following problems in practical applications: 1. Poor flatness retention: After long-term operation, traditional graphite-filled phenolic plastics suffer from poor interfacial bonding between graphite and resin, as well as water absorption and creep of the material itself. This leads to a rapid change in the surface roughness (Ra) of the valve cover and valve grid contact surface, resulting in a decrease in flatness and affecting long-term metering stability.

[0004] 2. Insufficient wear resistance: While high-filled graphite can reduce friction, it often comes at the cost of material density and mechanical strength. Under high pressure and micro-vibration environments, wear intensifies, limiting service life.

[0005] 3. High amount of molding waste: In traditional cold runner injection molding process, the raw material in the runner solidifies due to heat to form a slurry, which accounts for about 15%-20% of the total raw material consumption, resulting in huge material waste and solid waste treatment costs.

[0006] To address the aforementioned issues, there is an urgent need to develop a special material for valve grilles and covers that combines excellent wear resistance, long-term dimensional stability, and a low coefficient of friction. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a phenolic plastic for gas meter valve grille cover that has long-term stable flatness, excellent wear resistance, and is suitable for warm runner molding process.

[0008] A high-wear-resistant phenolic plastic for a gas meter valve grille cover is composed of the following components by weight: 60-85 parts phenolic resin, 10-25 parts spherical graphite, 10-20 parts needle-shaped petroleum coke, 7-20 parts composite wear-resistant agent, 2-5 parts bifunctional coupling agent, 3-8 parts carboxyl-terminated nitrile rubber, 8-15 parts curing agent, and 1-3 parts curing accelerator. The composite wear-resistant agent includes 3-8 parts polytetrafluoroethylene micropowder, 2-6 parts nano-silicon carbide, and 2-6 parts calcium stearate. The bifunctional coupling agent is a compound of γ-aminopropyltriethoxysilane (KH-550) and γ-glycidoxypropyltrimethoxysilane (KH-560) in a 1:1 mass ratio.

[0009] Spherical graphite forms a continuous lubricating film on the friction surface; its layered structure is easily sheared, forming a low-friction transfer film. Needle-shaped petroleum coke, as a rigid skeleton, is interwoven into the resin, forming a three-dimensional interlocking skeleton that inhibits creep and improves compressive strength. Polytetrafluoroethylene micropowder acts as a rigid "micro-protrusion" embedded in the friction surface, resisting ploughing and abrasive wear. Nano-SiC acts as anti-wear particles to resist ploughing, and calcium stearate provides internal lubrication and release functions. Bifunctional coupling agents and interfacial bridges chemically bond one end to the active groups on the surface of the composite wear-resistant agent, and react with the other end to terminal carboxyl-terminated butadiene-acrylonitrile rubber or phenolic resin to form covalent bonds.

[0010] Preferably, the spherical graphite has an average particle size of 8-20 μm; the needle-shaped petroleum coke has an aspect ratio ≥3 and an average length of 15-30 μm. The spherical graphite, with its smaller particle size (8-20 μm), has a larger specific surface area, making it easier to mix uniformly with resin. Furthermore, its spherical shape allows it to roll during friction, reducing frictional resistance. The needle-shaped petroleum coke, with an aspect ratio ≥3, oriented along the flow direction during kneading and injection molding, forming a three-dimensional interlocking framework that effectively inhibits resin curing shrinkage and water absorption creep.

[0011] Preferably, the average particle size of the polytetrafluoroethylene micropowder is 1-5 μm; and the average particle size of the nano-silicon carbide is 50-100 nm.

[0012] Preferably, the spherical graphite is epoxy-grafted modified graphite, and the needle-shaped petroleum coke is epoxy-grafted modified petroleum coke. The epoxy-grafted modified spherical graphite and needle-shaped petroleum coke (oxidized with dilute nitric acid + grafted with KH-560) have epoxy groups on their surfaces. These epoxy groups can ring-open to form ether bonds with the phenolic hydroxyl groups of phenolic resin (under the catalysis of an accelerator), ring-open to form ester bonds with the carboxyl groups of pre-activated CTBN, and add to form CN bonds with the amino groups on the surface of SiC treated with a coupling agent.

[0013] Preferably, the curing agent is hexamethylenetetramine; the curing accelerator is zinc oxide or magnesium oxide.

[0014] A method for preparing a gas meter valve grille cover using high wear-resistant phenolic plastic includes the following steps: A pre-composite wear-resistant agent is obtained by mixing the composite wear-resistant agent with 1 / 3 to 2 / 3 parts by weight of the bifunctional coupling agent, and a pre-activated toughening agent is obtained by mixing the carboxyl-terminated butadiene-acrylonitrile rubber with the remaining bifunctional coupling agent. Phenolic resin, pre-composite wear-resistant agent and curing accelerator were ball-milled to obtain resin premix; Spherical graphite, needle-shaped petroleum coke, resin premix, pre-activated toughening agent and curing agent are sequentially added to a kneader and kneaded. After cooling, crushing and sieving, a molding compound is obtained, which is then injection molded.

[0015] PTFE, SiC, and calcium stearate are mixed with a portion of the coupling agent to coat the wear-resistant particles, improving dispersion and interface. CTBN reacts with the remaining coupling agent to generate active CTBN with terminal silanol or amide bonds, enabling it to chemically bond with carbon materials or resins. Ball milling premixing ensures uniform distribution of resin, wear-resistant agent, and accelerator. Kneading and granulation ensure thorough mixing and partial pre-crosslinking of the components, forming a flowable molding compound. Injection molding employs a warm runner process to prevent material sticking.

[0016] Preferably, the composite wear-resistant agent is dry-mixed for 20-40 minutes, and then 1 / 3-2 / 3 parts by weight of the bifunctional coupling agent is added and mixed for 15-30 minutes to obtain the pre-composite wear-resistant agent; the carboxyl-terminated nitrile rubber is mixed with the remaining bifunctional coupling agent at 60-90℃ for 5-15 minutes to obtain the pre-activated toughening agent.

[0017] Preferably, in the ball milling step, the ball milling speed is 200-300 rpm and the ball milling time is 1-2 hours.

[0018] Preferably, the molding compound is obtained by kneading at 80-110℃ for 30-60 minutes, followed by cooling, crushing, and passing through an 80-120 mesh sieve.

[0019] Preferably, before the kneading step, the spherical graphite and needle-shaped petroleum coke are modified, including the following steps: the spherical graphite and needle-shaped petroleum coke are stirred in a 10-25% (w / w) dilute nitric acid solution in a water bath at 60-80°C for 1-3 hours to obtain an oxidized carbon material; the oxidized carbon material is dispersed in an ethanol aqueous solution, and 8-12% (w / w) of γ-glycidyl etheroxypropyltrimethoxysilane is added, and the mixture is refluxed at 70-80°C for 4-6 hours.

[0020] Oxidation with dilute nitric acid introduces -OH and -COOH groups onto the carbon surface, providing anchor points for grafting. The concentration, temperature, and time are carefully controlled to prevent excessive oxidation and damage to the carbon material. After hydrolysis of γ-glycidoxypropyltrimethoxysilane, silanols condense with surface -OH groups to form Si-OC bonds, allowing for the grafting of epoxy groups.

[0021] The present invention has the following beneficial effects: Spherical graphite rolls easily at the friction interface and forms a continuous lubricating film. Needle-shaped petroleum coke is oriented along the shear direction during kneading and injection molding flow, forming a three-dimensional skeleton. This skeleton prevents graphite from being over-compacted under pressure and losing its lubricating function. At the same time, it inhibits resin curing shrinkage and water absorption expansion, suppresses overall creep, and thus improves long-term dimensional stability.

[0022] The composite wear-resistant agent is composed of polytetrafluoroethylene micro powder, nano-silicon carbide, and calcium stearate. The polytetrafluoroethylene micro powder acts as a rigid "micro-protrusion" embedded in the friction surface to resist ploughing and abrasive wear. The nano-SiC acts as an anti-wear particle to resist ploughing, and the calcium stearate provides internal lubrication and release functions, forming a "soft-hard-auxiliary" synergistic system, which reduces the coefficient of friction and improves wear resistance.

[0023] One part of the bifunctional coupling agent is used to preactivate carboxyl-terminated nitrile butadiene rubber (NBR). The carboxyl groups at the end of the NBR react with the amino groups of the bifunctional coupling agent to form amide bonds, introducing hydrolyzable silanol groups or retained active groups at the end of the rubber molecular chain. This allows the NBR to be chemically anchored to the surface of the composite wear-resistant agent, thus improving the weak interfacial bonding between the NBR and the resin. The other part of the bifunctional coupling agent is used to coat the wear-resistant agent. The inorganic-loving end (silanol group) of the bifunctional coupling agent adsorbs or bonds to the silanol groups and calcium ions of calcium stearate on the SiC surface, while the organic-loving end (amino / epoxy group) extends outward, forming an "organic coating layer" on the surface of the wear-resistant agent particles. This coating layer significantly reduces the interfacial tension between the wear-resistant agent and the phenolic resin, allowing PTFE and SiC to be uniformly dispersed in the resin matrix, preventing agglomeration and enhancing the interfacial bonding strength.

[0024] The phenolic plastic provided by this invention is specifically designed for gas meter valve grilles and covers, offering advantages such as good molding processability, high product precision, and stable long-term performance. The resulting valve grilles and covers achieve a flatness of 0.008-0.012mm (depending on the flow range), fully meeting the requirements of high-end gas meters for core components and suitable for large-scale industrial production. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic flowchart illustrating the preparation method of the high wear-resistant phenolic plastic for the gas meter valve grille cover provided by the present invention. Detailed Implementation

[0026] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0027] A high-wear-resistant phenolic plastic for a gas meter valve grille cover is composed of the following components by weight: 60-85 parts phenolic resin, 10-25 parts spherical graphite, 10-20 parts needle-shaped petroleum coke, 7-20 parts composite wear-resistant agent, 2-5 parts bifunctional coupling agent, 3-8 parts carboxyl-terminated nitrile rubber, 8-15 parts curing agent, and 1-3 parts curing accelerator. The composite wear-resistant agent includes 3-8 parts polytetrafluoroethylene micro powder, 2-6 parts nano-silicon carbide, and 2-6 parts calcium stearate.

[0028] Spherical graphite forms a continuous lubricating film on the friction surface; its layered structure is easily sheared, forming a low-friction transfer film. Needle-shaped petroleum coke, as a rigid skeleton, is interwoven into the resin, forming a three-dimensional interlocking skeleton that inhibits creep and improves compressive strength. Polytetrafluoroethylene micropowder acts as a rigid "micro-protrusion" embedded in the friction surface, resisting ploughing and abrasive wear. Nano-SiC acts as anti-wear particles to resist ploughing, and calcium stearate provides internal lubrication and release functions. Bifunctional coupling agents and interfacial bridges chemically bond one end to the active groups on the surface of the composite wear-resistant agent, and react with the other end to terminal carboxyl-terminated butadiene-acrylonitrile rubber or phenolic resin to form covalent bonds.

[0029] like Figure 1 As shown, a method for preparing a high-wear-resistant phenolic plastic for a gas meter valve grille cover includes the following steps: A pre-composite wear-resistant agent is obtained by mixing the composite wear-resistant agent with 1 / 3 to 2 / 3 parts by weight of the bifunctional coupling agent, and a pre-activated toughening agent is obtained by mixing the carboxyl-terminated butadiene-acrylonitrile rubber with the remaining bifunctional coupling agent. Phenolic resin, pre-composite wear-resistant agent and curing accelerator were ball-milled to obtain resin premix; Spherical graphite, needle-shaped petroleum coke, resin premix, pre-activated toughening agent and curing agent are sequentially added to a kneader and kneaded. After cooling, crushing and sieving, a molding compound is obtained, which is then injection molded.

[0030] PTFE, SiC, and calcium stearate are mixed with a portion of the coupling agent to coat the wear-resistant particles, improving dispersion and interface. CTBN reacts with the remaining coupling agent to generate active CTBN with terminal silanol or amide bonds, enabling it to chemically bond with carbon materials or resins. Ball milling premixing ensures uniform distribution of resin, wear-resistant agent, and accelerator. Kneading and granulation ensure thorough mixing and partial pre-crosslinking of the components, forming a flowable molding compound. Injection molding employs a warm runner process to prevent material sticking.

[0031] The present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto. The raw materials used in the embodiments are all commercially available industrial products: the phenolic resin is a thermosetting phenolic resin (softening point 85-95℃); spherical graphite (average particle size 8-20μm, carbon content ≥99%); needle-shaped petroleum coke (after calcination, aspect ratio ≥3, average length 15-30μm); polytetrafluoroethylene micro powder (average particle size 1-5μm); nano-silicon carbide (average particle size 50-100nm); calcium stearate (industrial grade); the bifunctional coupling agent is a compound of γ-aminopropyltriethoxysilane (KH-550) and γ-glycidoxypropyltrimethoxysilane (KH-560) in a mass ratio of 1:1; carboxyl-terminated nitrile butadiene rubber (CTBN, acrylonitrile content 26%, carboxyl value 0.3 mmol / g); the curing agent is hexamethylenetetramine (HMTA); and the curing accelerator is zinc oxide.

[0032] Example 1

[0033] By weight: 60 parts phenolic resin, 10 parts spherical graphite, 10 parts needle-shaped petroleum coke, 7 parts composite wear-resistant agent (including 3 parts PTFE, 2 parts nano-SiC, and 2 parts calcium stearate), 2 parts bifunctional coupling agent, 3 parts CTBN, 8 parts curing agent, and 1 part curing accelerator.

[0034] Preparation method: Pre-composite wear-resistant agent: Dry mix PTFE, nano-SiC, and calcium stearate in a high-speed mixer for 20 minutes, add 1 / 3 of the bifunctional coupling agent (0.67 parts), and continue mixing for 15 minutes.

[0035] Pre-activated toughening agent: Mix CTBN with the remaining bifunctional coupling agent (1.33 parts) at 60°C for 5 minutes.

[0036] Resin premixing: Phenolic resin, pre-composite wear-resistant agent, and curing accelerator are ball-milled in a ball mill jar at 200 rpm for 1 hour.

[0037] Kneading and granulation: The modified carbon material, resin premix, pre-activated toughening agent and curing agent are kneaded in a kneader at 80°C for 30 minutes, cooled and pulverized through an 80-mesh sieve to obtain molding compound.

[0038] Warm runner injection molding: runner temperature 70℃, mold temperature 175℃, injection pressure 90 MPa, holding pressure for 25 seconds, demolding.

[0039] Post-treatment: Heat treatment at 170℃ for 2 hours.

[0040] Example 2

[0041] By weight: 85 parts phenolic resin, 25 parts spherical graphite, 20 parts needle-shaped petroleum coke, 20 parts composite wear-resistant agent (8 parts PTFE, 6 parts nano-SiC, 6 parts calcium stearate), 5 parts bifunctional coupling agent, 8 parts CTBN, 15 parts curing agent, and 3 parts curing accelerator.

[0042] Preparation method: Dry mix the pre-composite wear-resistant agent for 40 minutes, add 2 / 3 of the coupling agent (3.33 parts) and mix for 30 minutes; mix the pre-activated toughening agent at 90℃ for 15 minutes; ball mill at 300 rpm for 2 hours; knead at 110℃ for 60 minutes, and pass through a 120-mesh sieve; injection molding runner temperature at 90℃, mold temperature at 185℃, pressure at 120 MPa, and hold pressure for 40 seconds; post-treatment at 190℃ for 4 hours.

[0043] Example 3

[0044] By weight: 72 parts phenolic resin, 17 parts spherical graphite, 15 parts needle-shaped petroleum coke, 13 parts composite wear-resistant agent (5.5 parts PTFE, 4 parts nano-SiC, 3.5 parts calcium stearate), 3.5 parts bifunctional coupling agent, 5.5 parts CTBN, 11 parts curing agent, and 2 parts curing accelerator.

[0045] Preparation method: Dry mix the pre-composite wear-resistant agent for 30 minutes, add 1 / 2 coupling agent (1.75 parts) and mix for 22 minutes; mix the pre-activated toughening agent at 75℃ for 10 minutes; ball mill at 250 rpm for 1.5 hours; knead at 95℃ for 45 minutes, and pass through a 100-mesh sieve; injection molding runner temperature at 80℃, mold temperature at 180℃, pressure at 105 MPa, and hold pressure for 32 seconds; post-treatment at 180℃ for 3 hours.

[0046] Example 4

[0047] The composition is the same as in Example 3. The process parameters are as follows: dry mix the pre-composite wear-resistant agent for 20 minutes, add 1 / 3 of the coupling agent (1.17 parts) and mix for 15 minutes; mix the pre-activated toughening agent at 60°C for 5 minutes; ball mill at 200 rpm for 1 hour; knead at 80°C for 30 minutes, and pass through an 80-mesh sieve; injection molding runner at 70°C / 175°C / 90 MPa for 25 seconds; post-treatment at 170°C for 2 hours.

[0048] Example 5

[0049] The composition is the same as in Example 3. The process parameters are as follows: dry mix the pre-composite wear-resistant agent for 40 minutes, add 2 / 3 of the coupling agent (2.33 parts) and mix for 30 minutes; mix the pre-activated toughening agent at 90°C for 15 minutes; ball mill at 300 rpm for 2 hours; knead at 110°C for 60 minutes and pass through a 120-mesh sieve; injection molding runner at 90°C / 185°C / 120 MPa for 40 seconds; post-treatment at 190°C for 4 hours.

[0050] Example 6

[0051] The composition is the same as in Example 3, but the process adds a carbon material modification step; otherwise, it is the same as in Example 3.

[0052] Carbon material modification steps: Spherical graphite and needle-shaped petroleum coke were added to 10% dilute nitric acid, stirred in a water bath at 60°C for 1 hour, washed until neutral, and dried at 110°C. Then, they were dispersed in 95% ethanol, and KH-560 (8% by weight of carbon material) was added. The pH was adjusted to 4.5 with acetic acid, refluxed at 70°C for 4 hours, filtered and washed, and vacuum dried at 90°C to obtain epoxy-grafted carbon material.

[0053] Example 7

[0054] The composition is the same as in Example 3, but the process adds a carbon material modification step; otherwise, it is the same as in Example 3.

[0055] Carbon material modification steps: Carbon material modification involves treating with 25% dilute nitric acid at 80℃ for 3 hours, using 12% KH-560, and refluxing at 80℃ for 6 hours.

[0056] Comparative Example A commercially available graphite phenolic molding compound for gas meter valve covers was selected, and a traditional cold runner injection molding process was adopted. The mold temperature was 175℃, and the holding time was 40 seconds.

[0057] Tests: The coefficient of friction was tested according to GB / T 3960-2016, the specific wear rate was tested according to GB / T 3960-2016 "Plastics Sliding Friction and Wear Test Method", the flexural strength was tested according to GB / T 9341-2008, and the heat distortion temperature was tested according to GB / T 1634.2-2019. The results are shown in Table 1.

[0058] Table 1 Example 1 0.13 3.7 x 10 -6 ]]> 88 188 Example 2 0.10 3.5 x 10 -6 ]] 93 202 Example 3 0.11 3.2 x 10 -6 ]]> 96 196 Example 4 0.12 3.6 x 10 -6 ]] 92 192 Example 5 0.11 3.1 x 10 -6 ]] 98 199 Example 6 0.08 <![CDATA[2.5×10 -6 ]]> 101 211 Example 7 0.06 <![CDATA[2.3×10 -6 ]]> 103 213 Comparative Example 0.21 70 163 As shown in Table 1, the method of the present invention significantly improves the frictional properties, mechanical properties and dimensional stability.

[0059] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A high-wear-resistant phenolic plastic for a gas meter valve grille cover, characterized in that, The product is composed of the following components by weight: 60-85 parts phenolic resin, 10-25 parts spherical graphite, 10-20 parts needle-shaped petroleum coke, 7-20 parts composite wear-resistant agent, 2-5 parts bifunctional coupling agent, 3-8 parts carboxyl-terminated nitrile rubber, 8-15 parts curing agent, and 1-3 parts curing accelerator. The composite wear-resistant agent includes 3-8 parts polytetrafluoroethylene micro powder, 2-6 parts nano-silicon carbide, and 2-6 parts calcium stearate. The bifunctional coupling agent is a compound of γ-aminopropyltriethoxysilane (KH-550) and γ-glycidoxypropyltrimethoxysilane (KH-560) in a mass ratio of 1:

1.

2. The high wear-resistant phenolic plastic for the gas meter valve grille cover according to claim 1, characterized in that, The average particle size of the spherical graphite is 8-20 μm; the aspect ratio of the needle-shaped petroleum coke is ≥3, and the average length is 15-30 μm.

3. The high wear-resistant phenolic plastic for the gas meter valve grille cover according to claim 1, characterized in that, The average particle size of the polytetrafluoroethylene micro powder is 1-5 μm; the average particle size of the nano-silicon carbide is 50-100 nm.

4. The high wear-resistant phenolic plastic for the gas meter valve grille cover according to claim 1, characterized in that, The spherical graphite is epoxy-grafted modified graphite, and the needle-shaped petroleum coke is epoxy-grafted modified petroleum coke.

5. The high wear-resistant phenolic plastic for the gas meter valve grille cover according to claim 1, characterized in that, The curing agent is hexamethylenetetramine; the curing accelerator is zinc oxide or magnesium oxide.

6. A method for preparing a high-wear-resistant phenolic plastic for the gas meter valve grille cover according to any one of claims 1 to 5, characterized in that, Includes the following steps: A pre-composite wear-resistant agent is obtained by mixing the composite wear-resistant agent with 1 / 3 to 2 / 3 parts by weight of the bifunctional coupling agent, and a pre-activated toughening agent is obtained by mixing the carboxyl-terminated butadiene-acrylonitrile rubber with the remaining bifunctional coupling agent. Phenolic resin, pre-composite wear-resistant agent and curing accelerator were ball-milled to obtain resin premix; Spherical graphite, needle-shaped petroleum coke, resin premix, pre-activated toughening agent and curing agent are sequentially added to a kneader and kneaded. After cooling, crushing and sieving, a molding compound is obtained, which is then injection molded.

7. The preparation method according to claim 6, characterized in that, Dry mix the composite wear-resistant agent for 20-40 minutes, then add 1 / 3-2 / 3 parts by weight of the bifunctional coupling agent and mix for 15-30 minutes to obtain the pre-composite wear-resistant agent; mix the carboxyl-terminated nitrile rubber with the remaining bifunctional coupling agent at 60-90℃ for 5-15 minutes to obtain the pre-activated toughening agent.

8. The preparation method according to claim 6, characterized in that, In the ball milling process, the ball milling speed is 200-300 rpm and the ball milling time is 1-2 hours.

9. The preparation method according to claim 6, characterized in that, Knead at 80-110℃ for 30-60 minutes, then cool, crush, and pass through an 80-120 mesh sieve to obtain molding compound.

10. The preparation method according to claim 6, characterized in that, Before the kneading step, the spherical graphite and needle-shaped petroleum coke are modified, including the following steps: the spherical graphite and needle-shaped petroleum coke are stirred in a 10-25% (w / w) dilute nitric acid solution in a water bath at 60-80°C for 1-3 hours to obtain an oxidized carbon material; the oxidized carbon material is dispersed in an ethanol aqueous solution, and γ-glycidyl etheroxypropyltrimethoxysilane (8-12% by mass of the oxidized carbon material) is added, and the mixture is refluxed at 70-80°C for 4-6 hours.

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