High-strength corrosion-resistant aramid fiber composite material and preparation process thereof

Abstract

The invention discloses a high-strength corrosion-resistant aramid composite material and a preparation process thereof, and relates to the technical field of aramid composite materials, the high-strength corrosion-resistant aramid composite material comprises the following components by mass: 60-80 parts of ethylene propylene diene monomer, 20-40 parts of hydrogenated nitrile rubber, 10-15 parts of polytetrafluoroethylene, 18-30 parts of a filler, 10-15 parts of aramid fiber, 5-8 parts of a plasticizer, and 3-6 parts of a vulcanizing agent. The EPDM rubber, the hydrogenated nitrile rubber and the polytetrafluoroethylene are compounded, and the aramid fibers and the filler are added, so that the composite material with good mechanical property and corrosion resistance is obtained; by modifying the ethylene propylene diene monomer and the aramid fiber, the compatibility among the materials is improved, and the comprehensive performance of the composite material is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aramid composite materials, in particular to a high-strength corrosion-resistant aramid composite material and a preparation process thereof. Background Art

[0002] In order to prevent the leakage of fluids and solids from adjacent interfaces and the invasion of external impurities, seals are often installed to protect the interior of mechanical equipment. According to material classification, seals commonly use EPDM rubber, nitrile rubber, fluororubber, silicone, engineering plastics, etc. In order to cope with the mechanical stress, chemical erosion and long-term reliability under complex working conditions, seals need to have high strength and corrosion resistance. Aramid fiber has the characteristics of high strength, high temperature resistance, chemical corrosion resistance and low friction coefficient. Due to its excellent performance, these characteristics make aramid fiber perform well in seals. However, if EPDM rubber is used as the rubber matrix of the composite material, the strength and resistance to chemical media of the composite material still need to be improved. Therefore, we propose a high-strength and corrosion-resistant aramid composite material and its preparation process. Summary of the Invention

[0003] The object of the present invention is to provide a high-strength, corrosion-resistant aramid composite material and a preparation process thereof, so as to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solution: a high-strength corrosion-resistant aramid composite material, comprising the following components by mass: 60 to 80 parts of EPDM rubber, 20 to 40 parts of hydrogenated nitrile rubber, 10 to 15 parts of polytetrafluoroethylene, 18 to 30 parts of filler, 10 to 15 parts of aramid fiber, 5 to 8 parts of plasticizer, and 3 to 6 parts of vulcanizer.

[0005] Furthermore, the composite material further comprises 3 to 5 parts of zinc oxide, 3 to 5 parts of magnesium oxide, 0.5 to 1.0 parts of stearic acid, and 1.5 to 6.0 parts of auxiliary agents.

[0006] Furthermore, the filler is a mixture of one or more of carbon black, talc, mica powder, calcium silicate, chopped carbon fiber, nanoclay, barium sulfate, and fumed silica.

[0007] Furthermore, the filler is 3.2 to 6.0 parts of talc powder, 5.2 to 7.0 parts of chopped carbon fibers, 6.4 to 12.0 parts of barium sulfate, and 3.2 to 5.0 parts of fumed silica.

[0008] Furthermore, the vulcanizing agent is one or a mixture of two of sulfur, peroxide vulcanizing agent, phenolic resin vulcanizing agent, and triallyl isocyanurate.

[0009] Furthermore, the vulcanizing agent is a mixture of a peroxide vulcanizing agent and triallyl isocyanurate, with a mass ratio of (1.4-2):1;

[0010] The peroxide curing agent is curing agent DCP or curing agent BIPB.

[0011] The vulcanizing agent does not contain sulfur, which prevents the formation of acidic byproducts in corrosive environments and improves the corrosion resistance of the composite material. The inclusion of the co-crosslinking agent triallyl isocyanurate in the vulcanizing agent increases the crosslink density of the system, making the molecular structure more stable and enhancing the composite material's resistance to chemical corrosion.

[0012] Furthermore, the plasticizer is selected from TP-95, DOS or a mixture of the two.

[0013] Furthermore, the auxiliary agent includes: 1.0 to 1.5 parts of antioxidant, 1 to 2 parts of accelerator, and 1 to 2 parts of antiozonant;

[0014] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168, with a mass ratio of (1-2):1;

[0015] The accelerators are accelerator M, accelerator TMTDA, and accelerator ZDC, with a mass ratio of 1:1:1;

[0016] The antiozonant is one of microcrystalline wax and antiozonant 6PPD.

[0017] In the above technical solution, the EPDM matrix has excellent mechanical strength, weather resistance, ozone resistance, and chemical resistance, making it suitable for use as a sealant material. Hydrogenated nitrile rubber (HNBR) has a highly saturated molecular structure, which gives it excellent corrosion resistance and good resistance to a variety of chemicals. The addition of hydrogenated nitrile rubber (HNBR) can balance the weather resistance and oil resistance of the composite material, improving its oil resistance and acid and alkali resistance. The addition of polytetrafluoroethylene can enhance the chemical inertness of the composite material and reduce the friction coefficient, thereby further improving the corrosion resistance of the composite material.

[0018] The filler is a mixture of chopped carbon fibers, barium sulfate, fumed silica, and talcum powder, and is added to the composite material system in conjunction with aramid fibers. This can effectively enhance the mechanical strength, wear resistance, heat resistance, and dimensional stability of the composite material, achieving high strength of the composite material, which helps to improve the durability of the seal. Among them, carbon fibers provide rigidity, and aramid fibers focus more on improving toughness. The two are added together to form a physical cross-linked network, which macroscopically enhances the strength of the composite material, while fumed silica, barium sulfate, and talcum powder can fill microscopic defects, further improving the mechanical properties of the composite material. At the same time, barium sulfate is chemically inert and avoids adsorption of corrosive media. Aramid fibers and chopped carbon fibers have good corrosion resistance, which improves the chemical corrosion resistance of the composite material. The layered structure of talcum powder can block the inward diffusion of corrosive media, further enhancing the corrosion resistance of the composite material.

[0019] Active zinc oxide and light magnesium oxide are also added to the preparation system of the composite material, which can activate vulcanization and act as acid absorbers to neutralize the acidic substances produced during the vulcanization process and delay corrosion.

[0020] A preparation process of a high-strength, corrosion-resistant aramid composite material, comprising the following processes:

[0021] The EPDM rubber, hydrogenated nitrile rubber, polytetrafluoroethylene, filler, aramid fiber, plasticizer, zinc oxide, magnesium oxide, stearic acid and antioxidant are mixed and kneaded to obtain a rubber compound;

[0022] The rubber mixture obtained in the previous step is mixed and homogenized, and then vulcanized and formed to obtain a composite material.

[0023] Furthermore, the rubber compound is prepared by the following process:

[0024] Place EPDM rubber and hydrogenated nitrile rubber in an internal mixer and mix at 60-80°C for 2-3 minutes; add zinc oxide, magnesium oxide, stearic acid and antioxidant and continue mixing for 1-2 minutes; add plasticizer and mix for 2-3 minutes;

[0025] The filler is added in 2 to 3 times, and mixed for 2 to 3 minutes after each addition; the aramid fiber is added and mixed at a low speed for 2 to 4 minutes; the polytetrafluoroethylene is added and mixed for 1 to 2 minutes to obtain a compound rubber.

[0026] Furthermore, the process conditions for open milling and homogenization are: roller temperature 50-60°C, three thin passes, roller distance 1-3mm; mixing in vulcanizing agent and accelerator, and completion within 3 minutes.

[0027] Furthermore, the process conditions of vulcanization molding are: mold temperature 160-170°C; vulcanization temperature 170-180°C, pressure 15-20 MPa, and time 20-30 minutes.

[0028] Furthermore, after vulcanization molding, secondary vulcanization is performed, and the secondary vulcanization temperature is 150-160° C. and the duration is 3-4 hours.

[0029] In the above technical solution, secondary vulcanization can eliminate residual peroxides in the system and reduce the content of migratable small molecules, which helps to improve the comprehensive properties of the prepared composite material.

[0030] Furthermore, the EPDM rubber is partially replaced by modified EPDM rubber, with the replacement amount being 5 to 10 wt%;

[0031] The modified EPDM rubber is prepared by the following process:

[0032] Under nitrogen atmosphere, EPDM rubber is dissolved in toluene, 5-ethylidene-2-norbornene is added, and the mixture is stirred and mixed; a catalyst is added, and the mixture is stirred and reacted for 6 to 8 hours; ethanol is added for precipitation, washing, and drying to obtain modified EPDM rubber.

[0033] Furthermore, the mass ratio of EPDM rubber, 5-ethylidene-2-norbornene, and catalyst is 100:(0.3-0.5):(0.20-0.25);

[0034] The catalyst is Hoveyda-Grubbs-Ⅱ catalyst.

[0035] Furthermore, the ratio of EPDM rubber to toluene is (5-10) g / 100 mL;

[0036] The catalyst is added in the form of a toluene solution with a concentration of 5 to 15 wt%.

[0037] In the above technical solution, EPDM rubber and methyl acrylate are mixed in a solvent, and a cross-olefin metathesis reaction occurs in a nitrogen environment at room temperature under the action of a catalyst, thereby introducing a norbornene structure into the EPDM rubber molecular chain to produce a modified EPDM rubber with enhanced resistance to chemical media; and can significantly improve the compatibility between EPDM rubber and hydrogenated nitrile rubber, thereby improving the processing performance of the composite material; the intermolecular interaction force is increased, and the mechanical properties and corrosion resistance of the composite material are enhanced.

[0038] Furthermore, the aramid fiber is surface treated, and the specific process is as follows:

[0039] Aramid fiber and dopamine solution are mixed, stirred and reacted at a temperature of 30-60° C. for 4-6 hours; epichlorohydrin and sodium borohydride are added while maintaining the system temperature at 25-50° C., and stirred and reacted for 20-60 minutes to obtain chlorinated aramid fiber; 3-amino-4,4,4-trifluoro-2-butenenitrile is added, and the mixture is reacted at 40-60° C. for 60-90 minutes; centrifugation, washing, and drying are performed to obtain modified aramid fiber.

[0040] Furthermore, the molar ratio of dopamine, epichlorohydrin, and 3-amino-4,4,4-trifluoro-2-butenenitrile is 1:(1.5-2.5):(2.4-4.0);

[0041] The mass ratio of aramid fiber and dopamine is (5-6):1;

[0042] The molar ratio of epichlorohydrin to sodium borohydride is 10:(1-3).

[0043] Furthermore, 3-amino-4,4,4-trifluoro-2-butenenitrile is added in the form of N,N-dimethylformamide solution with a concentration of 5 to 10 wt%.

[0044] Furthermore, the concentration of the dopamine solution is 2-5 g / L; specifically, the dopamine solution is prepared by dissolving dopamine hydrochloride in 0.01 M Tris-HCl buffer solution and adjusting the pH to 8.5.

[0045] In the above technical solution, dopamine spontaneously reacts in an alkaline environment to form polydopamine, which deposits and adheres to the surface of the aramid fiber through van der Waals forces, hydrogen bonds, and π-π interactions, forming polydopamine-modified aramid fiber. This roughens the fiber surface and effectively enhances the interfacial properties between the rubber matrix and the aramid fiber without compromising the mechanical properties of the aramid fiber. Epichlorohydrin is then added. During the reaction between polydopamine and epichlorohydrin, the amino groups present in the incompletely oxidized dopamine units or at the ends of the polydopamine chains have high nucleophilicity and readily attack epoxy groups in an alkaline environment, resulting in aramid fiber with chlorine-modified surfaces, referred to as chlorinated aramid fiber. Sodium borohydride can be added to the reaction to prevent excessive oxidation of the polydopamine and inhibit the formation of quinones. Then, an excess of 3-amino-4,4,4-trifluoro-2-butenenitrile is added to enable it to be grafted onto the surface of the aramid fiber through the chlorine groups on the surface of the chlorinated aramid fiber, thereby functionalizing it and obtaining a modified aramid fiber containing elemental fluorine and polar nitrile groups.

[0046] The polydopamine on the surface of the modified aramid fiber enhances the interfacial bonding between the aramid fiber and hydrogenated nitrile rubber (polar rubber), making the aramid fiber more evenly dispersed in the composite and effectively reducing its agglomeration. This promotes the formation of strong interfacial bonding and improves the mechanical properties of the composite. The introduction of fluorinated groups reduces the friction coefficient, hinders the penetration of chemical media, and improves the composite's oil, corrosion, and wear resistance.

[0047] Furthermore, except for the chopped carbon fibers, the average particle size of the filler is 1 to 50 μm.

[0048] Furthermore, the filler is surface treated, and the specific process is as follows: while the filler is stirred at a low speed, the ethanol solution of KH-570 is slowly added over 10 to 15 minutes; then the mixture is stirred and reacted at 80 to 100° C. for 60 to 90 minutes; and dried and passed through a 200-mesh sieve.

[0049] Furthermore, in the ethanol solution of KH-570, the concentration of KH-570 is 1 to 2 wt %; the concentration of the ethanol solution is 50 to 90 v %, the pH is 4 to 5, and the hydrolysis is carried out for 30 to 60 minutes;

[0050] The amount of KH-570 used is 0.3-5% of the mass of the chopped carbon fiber.

[0051] In the above technical solution, the use of silane coupling agent to modify the filler can promote the uniform dispersion of the filler in the rubber matrix, thereby improving its processing performance and improving the durability of the composite material; it can also effectively improve the interfacial bonding ability between it and the rubber matrix, enhance the interaction force between the two, and enable the olefin group to participate in the vulcanization of the rubber, increase the cross-linking degree of the system, and enhance the mechanical properties, wear resistance, and corrosion resistance of the composite material.

[0052] Furthermore, the polytetrafluoroethylene (PTFE) is in powder form with an average particle size of 5 to 20 μm.

[0053] Furthermore, the polytetrafluoroethylene is surface treated, and the specific process is as follows: polytetrafluoroethylene powder is added to a high-speed mixer, and the titanate coupling agent solution is slowly sprayed into it under low-speed stirring for 10 to 15 minutes; the reaction is stirred at 60 to 80° C. for 20 to 30 minutes; and the solution is dried and passed through a 200-mesh sieve.

[0054] Furthermore, the polytetrafluoroethylene powder is subjected to oxygen plasma treatment before surface modification. The process conditions of the plasma treatment are: power 50-100W, duration 2-5min, air pressure 10-80Pa, oxygen flow rate 10-30sccm; the surface is activated to increase the active groups on the surface of the polytetrafluoroethylene powder, which is more convenient for subsequent surface treatment.

[0055] Furthermore, in the titanate coupling agent solution, the volume ratio of the titanate coupling agent to the ethanol solution is (5-10):1; the ethanol solution contains 0.1-0.5v% deionized water;

[0056] The dosage of titanate coupling agent is 1% to 3% of the mass of polytetrafluoroethylene powder;

[0057] The titanate coupling agent is one of KR-TTS and KR-138S.

[0058] Furthermore, the humidity of the surface treatment environment is 30% to 50%;

[0059] The rotation speed of low-speed stirring is 200-300 rpm; the rotation speed of stirring reaction is 1000-1500 rpm.

[0060] In the above technical solution, the surface treatment of polytetrafluoroethylene powder using a titanate coupling agent can reduce the agglomeration of polytetrafluoroethylene powder in the rubber matrix, promote its uniform dispersion, and help fully exert the performance of polytetrafluoroethylene in the composite material. DETAILED DESCRIPTION

[0061] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0062] In the following specific embodiments, the "parts" are all parts by mass, unless otherwise specified;

[0063] EPDM rubber: Kumho Asiana Group KEP350;

[0064] Hydrogenated nitrile rubber: Zetpol 2010L, acrylonitrile content 26.3%, Japan Zeon;

[0065] Polytetrafluoroethylene: powder with an average particle size of 12 μm, McLean;

[0066] Aramid fiber: 1500D, Korea ALKEX;

[0067] Chopped carbon fiber: PAN-based carbon fiber, diameter 5-10 μm, length 1-100 mm, Toray, Japan;

[0068] Talc: 2500 mesh, Anhui Gerui Minerals;

[0069] Barium sulfate: 1200 mesh, Hebei Bafeng;

[0070] Fumed silica: 1165MP, Qingdao Solviria Silica Co., Ltd.

[0071] Zinc oxide: Activated zinc oxide, purity 99.5%, Lingshou County Nanyu Mineral Products Processing Plant;

[0072] Magnesium oxide: Light magnesium oxide, purity 95%, Weifang Jiuzhuo Chemical Co., Ltd.

[0073] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168, with a mass ratio of 1:1;

[0074] The accelerators are accelerator M, accelerator TMTDA, and accelerator ZDC, with a mass ratio of 1:1:1;

[0075] The antiozonant is microcrystalline wax;

[0076] The filler was surface treated, and the process was as follows: while the filler was stirred at a low speed, the ethanol solution of KH-570 was slowly added over 15 minutes; then the mixture was stirred at 90°C for 75 minutes; dried, and passed through a 200-mesh sieve; the concentration of KH-570 in the ethanol solution was 2 wt%; the concentration of the ethanol solution was 80 v%, the pH was 4.5, and the mixture was hydrolyzed for 40 minutes; the amount of KH-570 was 3% of the mass of the chopped carbon fiber;

[0077] The polytetrafluoroethylene (PTFE) was surface treated in the following process: adding the oxygen plasma-treated PTFE powder to a high-speed mixer, and slowly spraying the titanate coupling agent KR-TTS solution into the mixture under low-speed stirring for 15 minutes; stirring the mixture at 70°C for 30 minutes; drying the mixture, and filtering the mixture through a 200-mesh sieve; the titanate coupling agent solution had a volume ratio of 9:1 to the ethanol solution; the ethanol solution contained 0.3% deionized water by volume; the titanate coupling agent was used in an amount of 3% by weight of the PTFE powder; the plasma treatment process conditions were: power 80W, duration 5 minutes, pressure 50 Pa, and oxygen flow rate 20 sccm;

[0078] The ambient humidity of the surface treatment was 40±5%; the rotation speed of the low-speed stirring was 250 rpm; the rotation speed of the stirring reaction was 1200 rpm;

[0079] The dopamine solution is prepared by dissolving dopamine hydrochloride in a 0.01 M Tris-HCl buffer solution and adjusting the pH to 8.5.

[0080] Example 1: A process for preparing a high-strength, corrosion-resistant aramid composite material, comprising the following steps:

[0081] Step 1. Under nitrogen atmosphere, dissolve EPDM rubber in toluene, add 5-ethylidene-2-norbornene, and stir to mix; add catalyst, stir and react for 6 hours; add ethanol to precipitate, wash, and dry to obtain modified EPDM rubber; the mass ratio of EPDM rubber, 5-ethylidene-2-norbornene, and catalyst is 100:0.3:0.20; the ratio of EPDM rubber to toluene is 5g / 100mL; catalyst Hoveyda-Grubbs-II is added in the form of a 5wt% toluene solution;

[0082] Step 2: Mix aramid fiber and 2g / L dopamine solution, stir and react at 30°C for 6h; keep the system temperature at 25°C, add epichlorohydrin and sodium borohydride, stir and react for 60min to obtain chlorinated aramid fiber; add 3-amino-4,4,4-trifluoro-2-butenenitrile, react at 40°C for 90min; centrifuge, wash, and dry to obtain modified aramid fiber; the molar ratio of dopamine, epichlorohydrin, and 3-amino-4,4,4-trifluoro-2-butenenitrile is 1:1.5:2.4; the mass ratio of aramid fiber and dopamine is 5:1; the molar ratio of epichlorohydrin and sodium borohydride is 10:1; 3-amino-4,4,4-trifluoro-2-butenenitrile is added in the form of a 5wt% N,N-dimethylformamide solution;

[0083] Step 3, placing EPDM rubber and hydrogenated nitrile rubber in an internal mixer and mixing at 60° C. for 3 minutes; adding zinc oxide, magnesium oxide, stearic acid and antioxidant, and continuing to mix for 2 minutes; adding plasticizer and mixing for 3 minutes; adding filler in 3 times, mixing for 3 minutes after each addition; adding modified aramid fiber and mixing at low speed for 4 minutes; adding polytetrafluoroethylene and mixing for 2 minutes to obtain a rubber compound;

[0084] The rubber mix obtained in the previous step was mixed and homogenized, with the following process: roller temperature of 50°C, three thin passes, and a roller distance of 1mm; vulcanizing agent and accelerator were mixed in within 3 minutes; vulcanization molding was carried out, with the following process: mold temperature of 160°C, vulcanization temperature of 170°C, pressure of 15MPa, time of 30 minutes; and secondary vulcanization at 150°C for 4 hours to obtain a composite material;

[0085] The composite material includes the following components by mass: 80 parts of EPDM rubber (containing 5wt% modified EPDM rubber), 20 parts of hydrogenated nitrile rubber, 10 parts of polytetrafluoroethylene, 18 parts of filler, 10 parts of modified aramid fiber, 5 parts of plasticizer, 3 parts of vulcanizing agent, 3 parts of zinc oxide, 3 parts of magnesium oxide, 0.5 parts of stearic acid, and 1.5 parts of additives; the filler is 3.2 parts of talc powder, 5.2 parts of chopped carbon fiber, 6.4 parts of barium sulfate, and 3.2 parts of fumed silica; the vulcanizing agent is a mixture of peroxide vulcanizer DCP and triallyl isocyanurate, with a mass ratio of 1.4:1; the additives include 1 part of antioxidant, 1 part of accelerator, and 1 part of antiozonant.

[0086] Example 2: A process for preparing a high-strength, corrosion-resistant aramid composite material, comprising the following steps:

[0087] Step 1. Under nitrogen atmosphere, dissolve EPDM rubber in toluene, add 5-ethylidene-2-norbornene, and stir to mix; add catalyst, stir and react for 7 hours; add ethanol to precipitate, wash, and dry to obtain modified EPDM rubber; the mass ratio of EPDM rubber, 5-ethylidene-2-norbornene, and catalyst is 100:0.4:0.22; the ratio of EPDM rubber to toluene is 8g / 100mL; catalyst Hoveyda-Grubbs-II is added in the form of a 10wt% toluene solution;

[0088] Step 2: Mix aramid fiber and 3.5 g / L dopamine solution, stir and react at 45° C. for 5 hours; keep the system temperature at 32° C., add epichlorohydrin and sodium borohydride, stir and react for 40 minutes to obtain chlorinated aramid fiber; add 3-amino-4,4,4-trifluoro-2-butenenitrile, react at 50° C. for 75 minutes; centrifuge, wash, and dry to obtain modified aramid fiber; the molar ratio of dopamine, epichlorohydrin, and 3-amino-4,4,4-trifluoro-2-butenenitrile is 1:2:3.2; the mass ratio of aramid fiber and dopamine is 5.5:1; the molar ratio of epichlorohydrin and sodium borohydride is 10:2; 3-amino-4,4,4-trifluoro-2-butenenitrile is added in the form of 8wt% N,N-dimethylformamide solution;

[0089] Step 3, placing EPDM rubber and hydrogenated nitrile rubber in an internal mixer and mixing at 70° C. for 2.5 minutes; adding zinc oxide, magnesium oxide, stearic acid and antioxidant, and continuing to mix for 1.5 minutes; adding plasticizer and mixing for 2.5 minutes; adding filler in three times, mixing for 2.5 minutes after each addition; adding modified aramid fiber and mixing at low speed for 3 minutes; adding polytetrafluoroethylene and mixing for 1.5 minutes to obtain a rubber mixture;

[0090] The rubber mix obtained in the previous step was mixed and homogenized at a roller temperature of 55°C, three thin passes, and a roller distance of 2mm. The vulcanizing agent and accelerator were mixed in within 3 minutes. The vulcanization molding process was performed at a mold temperature of 165°C, a vulcanization temperature of 175°C, a pressure of 18 MPa, and a duration of 25 minutes. The composite material was obtained by secondary vulcanization at 155°C for 3.5 hours.

[0091] The composite material includes the following components by mass: 70 parts of EPDM rubber (containing 7wt% modified EPDM rubber), 30 parts of hydrogenated nitrile rubber, 12 parts of polytetrafluoroethylene, 24 parts of filler, 12 parts of modified aramid fiber, 6 parts of plasticizer, 4.5 parts of vulcanizer, 4 parts of zinc oxide, 4 parts of magnesium oxide, 0.8 parts of stearic acid, and 3.6 parts of additives; the filler is 4.6 parts of talc powder, 6.1 parts of chopped carbon fiber, 9.2 parts of barium sulfate, and 4.1 parts of fumed silica; the vulcanizer is a mixture of peroxide vulcanizer DCP and triallyl isocyanurate, with a mass ratio of 1.7:1; the additives include: 1.2 parts of antioxidant, 1.2 parts of accelerator, and 1.2 parts of antiozonant.

[0092] Example 3: A process for preparing a high-strength, corrosion-resistant aramid composite material, comprising the following steps:

[0093] Step 1. Under nitrogen atmosphere, dissolve EPDM rubber in toluene, add 5-ethylidene-2-norbornene, and stir to mix; add catalyst, stir and react for 8 hours; add ethanol to precipitate, wash, and dry to obtain modified EPDM rubber; the mass ratio of EPDM rubber, 5-ethylidene-2-norbornene, and catalyst is 100:0.5:0.25; the ratio of EPDM rubber to toluene is 10g / 100mL; catalyst Hoveyda-Grubbs-II is added in the form of a 15wt% toluene solution;

[0094] Step 2: Mix aramid fiber and 5g / L dopamine solution, stir and react at 60°C for 4h; keep the system temperature at 50°C, add epichlorohydrin and sodium borohydride, stir and react for 20min to obtain chlorinated aramid fiber; add 3-amino-4,4,4-trifluoro-2-butenenitrile, react at 60°C for 60min; centrifuge, wash, and dry to obtain modified aramid fiber; the molar ratio of dopamine, epichlorohydrin, and 3-amino-4,4,4-trifluoro-2-butenenitrile is 1:2.5:4.0; the mass ratio of aramid fiber and dopamine is 6:1; the molar ratio of epichlorohydrin and sodium borohydride is 10:3; 3-amino-4,4,4-trifluoro-2-butenenitrile is added in the form of a 10wt% N,N-dimethylformamide solution;

[0095] Step 3, placing EPDM rubber and hydrogenated nitrile rubber in an internal mixer and mixing at 80° C. for 2 minutes; adding zinc oxide, magnesium oxide, stearic acid and antioxidant, and continuing to mix for 1 minute; adding plasticizer and mixing for 2 minutes; adding filler in two times, mixing for 2 minutes after each addition; adding aramid fiber and mixing at low speed for 2 minutes; adding polytetrafluoroethylene and mixing for 1 minute to obtain a rubber mixture;

[0096] The rubber mix obtained in the previous step was mixed and homogenized, with the following process: roller temperature of 60°C, three thin passes, and a roller distance of 3mm; vulcanizing agent and accelerator were mixed in within 3 minutes; vulcanization molding was carried out, with the following process: mold temperature of 170°C; vulcanization temperature of 180°C, pressure of 15MPa, time of 20 minutes; and secondary vulcanization at 160°C for 3 hours to obtain a composite material;

[0097] The composite material includes the following components by mass: 60 parts of EPDM rubber (containing 10wt% modified EPDM rubber), 40 parts of hydrogenated nitrile rubber, 15 parts of polytetrafluoroethylene, 30 parts of filler, 15 parts of modified aramid fiber, 8 parts of plasticizer, 6 parts of vulcanizer, 5 parts of zinc oxide, 5 parts of magnesium oxide, 1.0 part of stearic acid, and 6.0 parts of additives; the filler is 6.0 parts of talc powder, 7.0 parts of chopped carbon fiber, 12.0 parts of barium sulfate, and 5.0 parts of fumed silica; the vulcanizer is a mixture of peroxide vulcanizer BIPB and triallyl isocyanurate, with a mass ratio of 2:1; the additives include: 1.5 parts of antioxidant, 2 parts of accelerator, and 2 parts of antiozonant.

[0098] Comparative Example 1: A preparation process of a high-strength, corrosion-resistant aramid composite material, comprising the following processes:

[0099] Steps 1 / 2 are the same as steps 2 / 3 in Example 1 to obtain a composite material, which includes the following components by mass: 80 parts of EPDM rubber, 20 parts of hydrogenated nitrile rubber, 10 parts of polytetrafluoroethylene, 18 parts of filler, 10 parts of modified aramid fiber, 5 parts of plasticizer, 3 parts of vulcanizing agent, 3 parts of zinc oxide, 3 parts of magnesium oxide, 0.5 parts of stearic acid, and 1.5 parts of additives.

[0100] Comparative Example 2: A preparation process for a high-strength, corrosion-resistant aramid composite material, comprising the following processes:

[0101] Step 1: Mix aramid fiber and 2 g / L dopamine solution, stir and react at 30° C. for 6 hours; maintain the system temperature at 25° C., add KH570, stir and react for 60 minutes; centrifuge, wash, and dry to obtain modified aramid fiber; the molar ratio of dopamine to KH570 is 1:1.5; the mass ratio of aramid fiber to dopamine is 5:1;

[0102] Step 2 is the same as step 2 in Comparative Example 1 to obtain a composite material.

[0103] Comparative Example 3: A preparation process of a high-strength, corrosion-resistant aramid composite material, comprising the following processes:

[0104] Step 1: Mix aramid fiber and 2 g / L dopamine solution, stir and react at 30° C. for 6 hours; maintain the system temperature at 25° C., add trifluoropropane trimethoxysilane, stir and react for 60 minutes; centrifuge, wash, and dry to obtain modified aramid fiber; the molar ratio of dopamine to trifluoropropane trimethoxysilane is 1:1.5; and the mass ratio of aramid fiber to dopamine is 5:1;

[0105] Step 2 is the same as step 2 in Comparative Example 1 to obtain a composite material.

[0106] Comparative Example 4: A preparation process for a high-strength, corrosion-resistant aramid composite material, comprising the following processes:

[0107] Step 1. Under low-speed stirring, slowly add the ethanol solution of KH-570 to the aramid fiber for 15 minutes; then stir and react at 90°C for 75 minutes; dry and pass through a 200-mesh sieve; the concentration of KH-570 in the ethanol solution is 2wt%; the concentration of the ethanol solution is 80v%, the pH is 4.5, and the hydrolysis is carried out for 40 minutes; the amount of KH-570 is 3% of the mass of the chopped carbon fiber; the ambient humidity of the surface treatment is 40±5%; the low-speed stirring speed is 250rpm; the stirring reaction speed is 1200rpm;

[0108] Step 2 is the same as step 2 in Comparative Example 1 to obtain a composite material.

[0109] Experiment: Take the composite materials obtained in Examples 1-3 and Comparative Examples 1-4, prepare samples, test their properties and record the test results:

[0110] Mechanical properties test: GB / T 528 is used as the reference standard, and a universal testing machine is used to test the tensile properties of the sample at a tensile rate of 500 mm / min; GB / T 529 is used as the reference standard to test the tear strength of the sample;

[0111] Hardness test: GB / T 231.1 is used as the reference standard, and a Shore hardness tester is used to test the hardness of the sample;

[0112] Oil resistance test: Place the sample in IRM903 standard oil at 70°C, take it out and dry it after 72 hours, and measure the volume change rate of the sample before and after the test;

[0113] Corrosion resistance test: Place the samples in 10% sulfuric acid / 10% sodium hydroxide, take them out and dry them after 168 hours, and measure the mass change rate of the samples before and after the test;

[0114] Wear resistance test: GB / T 9867 was used as the reference standard. The wear rate of the sample was tested using an abrasion testing machine with a load of 10 N, a rotation speed of 0.1 m / s, and a duration of 30 min.

[0115]

[0116] According to the data in the above table, we can clearly draw the following conclusions:

[0117] The composite materials obtained in Examples 1-3 were compared with the composite materials obtained in Comparative Examples 1-4. The test results show that:

[0118] Compared to the comparative examples, the composite materials obtained in Examples 1-3 exhibited higher strength and hardness data, exhibited smaller changes in volume and mass under the action of gasoline, acids, and alkalis, and exhibited lower friction and wear. This demonstrates that the present invention improves the mechanical properties, oil resistance, and corrosion resistance of the composite materials, as well as their wear resistance.

[0119] Compared to Example 1, the composite material of Comparative Example 1 did not contain modified EPDM rubber. Compared to Comparative Example 1, the aramid fibers in Comparative Example 2 were modified with dopamine and KH570; the aramid fibers in Comparative Example 3 were modified with dopamine and trifluoropropane trimethoxysilane; and the aramid fibers in Comparative Example 4 were modified with KH570. The composite materials obtained in Comparative Examples 1-4 exhibited decreased strength and hardness, increased volume and mass changes under the influence of gasoline, acids, and alkalis, and increased friction and wear. This demonstrates that the present invention's design of the composite material components and process can improve the composite material's comprehensive mechanical properties, oil resistance, corrosion resistance, and wear resistance.

[0120] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A high-strength, corrosion-resistant aramid composite material, characterized by: The invention comprises the following components by mass: 60 to 80 parts of EPDM rubber, 20 to 40 parts of hydrogenated nitrile rubber, 10 to 15 parts of polytetrafluoroethylene, 18 to 30 parts of filler, 10 to 15 parts of aramid fiber, 5 to 8 parts of plasticizer and 3 to 6 parts of vulcanizing agent.

2. The high-strength, corrosion-resistant aramid composite material according to claim 1, characterized in that: The filler is a mixture of one or more of carbon black, talc powder, mica powder, calcium silicate, chopped carbon fiber, nano clay, barium sulfate, and fumed silica.

3. The high-strength, corrosion-resistant aramid composite material according to claim 1, characterized in that: The vulcanizing agent is a mixture of a peroxide vulcanizing agent and triallyl isocyanurate, with a mass ratio of (1.4-2):

1.

4. A process for preparing a high-strength, corrosion-resistant aramid composite material, characterized by: Including the following processes: The EPDM rubber, hydrogenated nitrile rubber, polytetrafluoroethylene, filler, aramid fiber, plasticizer, zinc oxide, magnesium oxide, stearic acid and antioxidant are mixed and kneaded to obtain a rubber compound; The rubber mixture obtained in the previous step is mixed and homogenized, and then vulcanized and formed to obtain a composite material.

5. The process for preparing a high-strength, corrosion-resistant aramid composite material according to claim 4, characterized in that: The EPDM rubber is partially replaced with modified EPDM rubber, with the replacement amount being 5 to 10 wt%; The modified EPDM rubber is prepared by the following process: Under nitrogen atmosphere, EPDM rubber is dissolved in toluene, 5-ethylidene-2-norbornene is added, and the mixture is stirred and mixed; a catalyst is added, and the mixture is stirred and reacted for 6 to 8 hours; ethanol is added for precipitation, washing, and drying to obtain modified EPDM rubber.

6. The process for preparing a high-strength, corrosion-resistant aramid composite material according to claim 5, characterized in that: The mass ratio of EPDM rubber to 5-ethylidene-2-norbornene is 100:(0.3-0.5).

7. The process for preparing a high-strength, corrosion-resistant aramid composite material according to claim 4, characterized in that: The aramid fiber is surface treated, and the specific process is as follows: Aramid fiber and dopamine solution are mixed, stirred and reacted at a temperature of 30-60°C for 4-6 hours; epichlorohydrin and sodium borohydride are added while maintaining the system temperature at 25-50°C, and stirred and reacted for 20-60 minutes to obtain chlorinated aramid fiber; 3-amino-4,4,4-trifluoro-2-butenenitrile is added, and the mixture is reacted at 40-60°C for 60-90 minutes to obtain modified aramid fiber.

8. The process for preparing a high-strength, corrosion-resistant aramid composite material according to claim 7, characterized in that: The molar ratio of dopamine, epichlorohydrin and 3-amino-4,4,4-trifluoro-2-butenenitrile is 1:(1.5-2.5):(2.4-4.0).

9. The process for preparing a high-strength, corrosion-resistant aramid composite material according to claim 7, characterized in that: The mass ratio of aramid fiber to dopamine is (5-6):

1.

10. The process for preparing a high-strength, corrosion-resistant aramid composite material according to claim 7, characterized in that: The molar ratio of epichlorohydrin to sodium borohydride is 10:(1-3).

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