Modified zinc oxide and its applications, UV-ozone resistant self-lubricating materials and their preparation methods and applications

Abstract

This invention provides modified zinc oxide and its applications, UV- and ozone-resistant self-lubricating materials and their preparation methods and applications, relating to the field of composite material technology. The modified zinc oxide provided by this invention is obtained by grafting zinc oxide onto a silane coupling agent using 2-mercaptobenzimidazole. The modified zinc oxide provided by this invention combines the excellent aging resistance of 2-mercaptobenzimidazole with the excellent UV absorption properties of zinc oxide, while also improving the dispersibility of nano-zinc oxide and overcoming the volatilization and migration problems of 2-mercaptobenzimidazole. This significantly improves the UV and ozone resistance of resin composites and effectively enhances their wear resistance. Resin composites filled with modified zinc oxide exhibit good reliability and service life in near-space environments, and show promising application prospects as self-lubricating pad materials for steering, load-bearing, rotating, and bushing components of aircraft.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, specifically to a modified zinc oxide and its application, a UV-ozone resistant self-lubricating material and its preparation method and application. Background Technology

[0002] Self-lubricating gasket materials are dense, high-performance functional composite materials made from special fibers and functionalized resins through tribological performance design and resin curing processes. They can be used in load-bearing and steering mechanical components of aircraft, such as rotor systems, transmission systems, rudders, and landing gear, serving to bear loads, resist wear, and reduce friction. The cruising altitude of aircraft is generally around 8–24 km, an airspace characterized by large diurnal temperature variations, high ultraviolet radiation intensity (290–400 nm), and high ozone concentration (10⁻⁶ ppm). 12 pcs / cm 3 Ultraviolet light and ozone have strong catalytic and oxidizing properties, and readily react with unsaturated chemical bonds in polymer materials, leading to the breakage of some molecular chains, amplifying existing micro-defects in the material, and accelerating the aging and performance degradation of the polymer material.

[0003] Chinese patent CN111188116A discloses a polyetheretherketone fiber-based self-lubricating fabric, which is woven from polyetheretherketone fibers and polytetrafluoroethylene fibers. This self-lubricating fabric has the characteristics of low coefficient of friction, excellent wear resistance and high bonding strength, and is suitable for use in low-speed and high-load environments. Chinese patent CN113089327A discloses an aramid III fiber reinforced self-lubricating pad composite material. The material uses sized aramid III fibers as weft yarns and aramid III fiber and PTFE fiber twisted yarns as warp yarns, woven on a loom. After desizing, the fabric is first activated by immersing in an aqueous solution of tannic acid-aminopropyltriethoxysilane, then reinforced by a hydrothermal interface reaction in a MgAl-LDH precursor solution. Next, it is thickened by immersing in a dopamine-polyethyleneimine buffer solution, and finally toughened by aramid nanofibers. This yields a strong-toughness integrated interface-modified aramid III / PTFE fabric. The aramid III fiber reinforced self-lubricating pad exhibits excellent mechanical and tribological properties, significantly improving the performance of fabric-based self-lubricating pad composite materials and enhancing the overall performance of fabric-type self-lubricating components. This material is suitable for high-temperature and high-load operating conditions. Chinese patent CN110819064A discloses a high thermal conductivity and wear-resistant self-lubricating pad, which features high thermal conductivity and good wear resistance, making it suitable for use as a sliding bearing pad. Chinese patent CN106435923A discloses a self-lubricating fabric composed of fluorinated resin yarn and other yarns, possessing advantages such as low coefficient of friction and good wear resistance, suitable for use in low-speed, high-load, and high- or low-temperature environments. Chinese patent CN111364256A discloses a self-lubricating fabric composite material, employing dopamine-modified single-walled nanotube reinforced polytetrafluoroethylene-aramid fabric composite material, exhibiting better wear resistance and excellent specific strength. However, none of the above polymer composite materials possess UV-ozone resistance, making them highly susceptible to corrosion from the combined effects of UV and ozone in near-space when used as self-lubricating pad materials, leading to performance degradation or failure, and consequently reducing the reliability of components such as joint bearings, bushings, and landing gear in aircraft.

[0004] To improve the UV-ozone resistance of polymer composites, a common method is to add light stabilizers and antioxidants as fillers in a certain proportion. Nano-zinc oxide is an excellent inorganic UV absorber with excellent UV shielding ability, a wide UV absorption wavelength range, and good transparency. It also possesses stable physicochemical properties and good thermal stability. However, the presence of numerous hydroxyl groups on the surface of nano-zinc oxide makes it hydrophilic, oleophobic, and polar, and its high surface energy makes it prone to agglomeration in the resin matrix, further affecting its UV resistance and wear resistance in the material. 2-Mercaptobenzimidazole (MB) is a hydrogen peroxide decomposition-type antioxidant that can decompose ROOH generated during the thermo-oxidative aging process of composite materials, transforming it into a more stable substance, thereby inhibiting material aging. However, MB volatilizes and migrates during processing, affecting the aging effect of the material. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a modified zinc oxide and its application, a UV-ozone aging resistant self-lubricating material and its preparation method and application. The modified zinc oxide provided by the present invention has high dispersibility in resin composite materials and can improve the UV aging resistance, ozone aging resistance and wear resistance of resin composite materials.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a modified zinc oxide, which is obtained by grafting zinc oxide with a silane coupling agent using 2-mercaptobenzimidazole.

[0008] Preferably, the mass ratio of the silane coupling agent grafted with zinc oxide to 2-mercaptobenzimidazole is 1:0.01 to 0.08.

[0009] This invention provides the application of the modified zinc oxide described in the above technical solution as a filler in resin composite materials.

[0010] This invention provides a self-lubricating material resistant to UV-ozone aging, comprising the following raw materials in parts by weight: 50-80 parts of polytetrafluoroethylene / reinforced fiber blended fabric, 18-50 parts of resin, and 2-10 parts of modified zinc oxide as described in the above technical solution.

[0011] Preferably, the mass ratio of polytetrafluoroethylene (PTFE) to reinforcing fiber in the PTFE / reinforcing fiber blended fabric is 1:0.5 to 1.8.

[0012] The reinforcing fibers include one or more of aramid, glass fiber, carbon fiber, and poly(p-phenylenebenzodioxazole) fiber.

[0013] This invention provides a method for preparing the UV-ozone resistant self-lubricating material described in the above technical solution, comprising the following steps:

[0014] A self-lubricating fabric impregnation solution is obtained by mixing resin, modified zinc oxide, and organic solvent.

[0015] The polytetrafluoroethylene / reinforced fiber blended fabric is immersed in the self-lubricating fabric impregnation solution and then dried to obtain a pre-impregnated fabric.

[0016] The preimpregnated material is cured to obtain a self-lubricating material resistant to UV-ozone aging.

[0017] Preferably, the organic solvent is a mixture of ketone solvents, alcohol solvents, and ester solvents;

[0018] The resin includes phenolic resin and / or polyimide resin;

[0019] The mass ratio of the resin to the volume of the organic solvent is 1 g: 4-9 mL.

[0020] Preferably, the mass ratio of the polytetrafluoroethylene / reinforced fiber blend to the preimpregnated material is 1:1.1 to 1.4.

[0021] Preferably, the curing pressure is 0.1-0.5 MPa, the temperature is 160-190°C, and the time is 1-2 hours.

[0022] The present invention also provides the application of the UV-ozone aging resistant self-lubricating material described in the above technical solution or the UV-ozone aging resistant self-lubricating material prepared by the preparation method described in the above technical solution as a self-lubricating pad material in aircraft.

[0023] This invention provides a modified zinc oxide, obtained by grafting zinc oxide with a silane coupling agent using 2-mercaptobenzimidazole. In the modified zinc oxide provided by this invention, the introduction of the silane coupling agent significantly reduces the number of hydroxyl groups on the zinc oxide surface, improves the oleophilicity of the nano-zinc oxide particles, and enhances the dispersibility of nano-zinc oxide in the resin matrix. The presence of zinc oxide greatly improves the thermal stability of 2-mercaptobenzimidazole, thereby overcoming the volatilization and migration problems of 2-mercaptobenzimidazole. The modified zinc oxide provided by this invention combines the excellent aging resistance of 2-mercaptobenzimidazole with the excellent UV absorption properties of zinc oxide, while overcoming the shortcomings of both. When used as a filler in resin composites, it can eliminate free radicals and peroxides generated by UV-ozone reactions, thereby significantly improving the UV resistance and ozone resistance of the resin composites. Furthermore, the modified zinc oxide provided by this invention exhibits better interfacial adsorption capacity, enhancing its adhesion to resins and improving the degree of cross-linking in the resin matrix. This allows the modified zinc oxide to effectively function as a heterojunction filler. Simultaneously, zinc oxide itself possesses good load-bearing capacity; the synergistic effect of these two factors effectively improves the load-bearing capacity and wear resistance of the resin composite material. After modification with silane coupling agents and 2-mercaptobenzimidazole, the surface roughness and the number of surface functional groups of zinc oxide increase, significantly enhancing the interfacial bonding force with the resin matrix, resulting in a 12-18% increase in adhesive strength.

[0024] This invention provides a UV-ozone resistant self-lubricating material, comprising the following raw materials in parts by weight: 50-80 parts of polytetrafluoroethylene / reinforced fiber blended fabric, 20-40 parts of resin, and 2-10 parts of modified zinc oxide as described in the above technical solution. In the UV-ozone resistant self-lubricating material provided by this invention, the modified zinc oxide acts as a heterojunction filler, effectively improving the wear resistance of the self-lubricating material. In environments with strong ultraviolet radiation and high ozone concentrations, 2-mercaptobenzimidazole and zinc oxide can produce a synergistic effect, enabling the modified zinc oxide to eliminate free radicals and peroxides generated by UV-ozone action, significantly reducing the aging effects of UV light and ozone on the self-lubricating material, protecting it from further corrosion by UV-ozone action, and endowing the self-lubricating material with excellent UV-ozone aging resistance. The UV-ozone aging resistant self-lubricating material provided by this invention has excellent UV-ozone aging resistance and wear resistance, high bonding strength with steel substrates or aerospace metal materials, good reliability and service life in near-space environments, and has good application prospects as a self-lubricating pad material for steering, load-bearing, rotating and bushing components of aircraft. Attached Figure Description

[0025] Figure 1 This is a flowchart of the preparation process for modified zinc oxide. Detailed Implementation

[0026] This invention provides a modified zinc oxide, which is obtained by grafting zinc oxide with a silane coupling agent using 2-mercaptobenzimidazole.

[0027] In this invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0028] In this invention, the preferred method for preparing silane coupling agent-grafted zinc oxide includes the following steps: mixing zinc oxide, silane coupling agent and alcohol solvent, and carrying out a grafting reaction to obtain silane coupling agent-grafted zinc oxide.

[0029] In this invention, the zinc oxide particle size is preferably ≤25 μm, and the zinc oxide preferably includes one or more of disc-shaped zinc oxide, rod-shaped zinc oxide, and zinc oxide nanoparticles, more preferably including disc-shaped zinc oxide, rod-shaped zinc oxide, or zinc oxide nanoparticles. In this invention, the zinc oxide is preferably commercially available zinc oxide or prepared in-house. In this invention, the preparation method of the disc-shaped zinc oxide preferably includes the following steps: mixing a water-soluble zinc source, an inorganic strong base, and water, and carrying out a hydrothermal reaction to obtain disc-shaped zinc oxide. In this invention, the water-soluble zinc source preferably includes zinc acetate and / or zinc nitrate; the inorganic strong base is preferably a hydroxide, more preferably sodium hydroxide and / or potassium hydroxide; the mass ratio of the water-soluble zinc source to the inorganic strong base is preferably 20-30:1, more preferably 25-30:1. In this invention, the mass ratio of the water-soluble zinc source to water is preferably 1:9 to 11, more preferably 1:9.5 to 10.5, and even more preferably 1:10. This invention does not have any particular limitation on the mixing process; it is sufficient to mix the raw materials evenly, such as by stirring. The mixing temperature is preferably room temperature, and the mixing time is 5 to 30 minutes, more preferably 10 to 20 minutes. In this invention, the hydrothermal reaction temperature is preferably 100 to 160°C, more preferably 100 to 130°C; the hydrothermal reaction time is preferably 10 to 26 hours, more preferably 10 to 20 hours; the hydrothermal reaction is preferably carried out under a protective atmosphere, which preferably includes nitrogen, argon, or helium. After the hydrothermal reaction is completed, the present invention preferably further includes post-processing, which preferably includes: solid-liquid separation of the obtained hydrothermal reaction liquid, drying of the obtained solid product to obtain disc-shaped zinc oxide; the present invention does not have a special limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as centrifugation; the drying temperature is preferably 50-90℃, more preferably 50-80℃, and the present invention does not have a special limitation on the drying time, drying to constant weight is sufficient.

[0030] In this invention, the silane coupling agent preferably includes one or more of 3-chloropropyltriethoxysilane (KH-550), γ-methacryloxypropyltrimethoxysilane (KH570), and γ-glycidoxypropyltrimethoxysilane (KH560), more preferably including KH-550, KH570, or KH560. In this invention, the mass ratio of zinc oxide to the silane coupling agent is preferably 1:0.01 to 0.05, more preferably 1:0.02 to 0.04, and even more preferably 1:0.03.

[0031] In this invention, the alcohol solvent is preferably ethanol, and the alcohol solvent is preferably a dry alcohol solvent; the mass ratio of zinc oxide to the volume of the alcohol solvent is preferably 1g:20-80mL, more preferably 1g:30-70mL, and even more preferably 1g:40-60mL.

[0032] In this invention, the preferred mixing method is to disperse zinc oxide in an alcohol solvent and then stir and mix the resulting zinc oxide dispersion with a silane coupling agent. The dispersion temperature is preferably room temperature. This invention does not have any special limitations on the dispersion and mixing temperature and time, as long as the raw materials can be mixed.

[0033] In this invention, the temperature of the grafting reaction is preferably 40-60°C, more preferably 45-55°C, and even more preferably 50°C; the time of the grafting reaction is preferably 20-30 h, more preferably 20-28 h, and even more preferably 20-25 h; the grafting reaction is preferably carried out under stirring conditions.

[0034] After the grafting reaction is completed, the present invention preferably further includes post-processing, which preferably includes: solid-liquid separation of the obtained grafting reaction solution, drying of the obtained solid product to obtain silane coupling agent grafted zinc oxide; the present invention does not have a special limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as centrifugation; the drying temperature is preferably 70-90°C, more preferably 80°C, and the present invention does not have a special limitation on the drying time, and drying to constant weight is sufficient.

[0035] In this invention, the method for preparing the modified zinc oxide preferably includes the following steps: grafting zinc oxide with a silane coupling agent, 2-mercaptobenzimidazole, an inorganic strong base and an alcohol solvent, and carrying out a modification reaction to obtain modified zinc oxide.

[0036] In this invention, the mass ratio of the silane coupling agent grafted with zinc oxide to 2-mercaptobenzimidazole is preferably 1:0.01 to 0.08, more preferably 1:0.02 to 0.06, and even more preferably 1:0.04 to 0.05.

[0037] In this invention, the inorganic strong base is preferably a hydroxide, more preferably sodium hydroxide and / or potassium hydroxide; the mass ratio of the silane coupling agent grafted zinc oxide to the inorganic strong base is preferably 1:0.01 to 0.02, more preferably 1:0.01 to 0.015, and even more preferably 1:0.01.

[0038] In this invention, the alcohol solvent is preferably ethanol, and the alcohol solvent is preferably a dry alcohol solvent; the mass ratio of the silane coupling agent grafted with zinc oxide to the volume ratio of the alcohol solvent is preferably 1g:50-150mL, more preferably 1g:60-120mL, and even more preferably 1g:60-100mL.

[0039] In this invention, the mixing is preferably carried out by dispersing silane coupling agent-grafted zinc oxide in an alcohol solvent, and then stirring and mixing the resulting silane coupling agent-grafted zinc oxide dispersion with 2-mercaptobenzimidazole and an inorganic strong base. The dispersion temperature is preferably room temperature. This invention does not have any special limitations on the dispersion and mixing temperature and time, as long as the raw materials can be mixed.

[0040] In this invention, the temperature of the modification reaction is preferably 40-60°C, more preferably 45-55°C, and even more preferably 50°C; the time of the modification reaction is preferably 20-30 h, more preferably 20-28 h, and even more preferably 20-25 h; the modification reaction is preferably carried out under stirring conditions.

[0041] After the modification reaction is completed, the present invention preferably further includes post-processing, which preferably includes: solid-liquid separation of the obtained modified reaction solution, drying of the obtained solid product to obtain silane coupling agent grafted zinc oxide; the present invention does not have a special limitation on the solid-liquid separation, and any solid-liquid separation method known to those skilled in the art can be used, such as centrifugation; the drying temperature is preferably 70-90°C, more preferably 80°C, and the present invention does not have a special limitation on the drying time, drying to constant weight is sufficient.

[0042] This invention provides the application of the modified zinc oxide described in the above technical solution as a filler in resin composite materials.

[0043] This invention provides a self-lubricating material resistant to UV-ozone aging, comprising the following raw materials in parts by weight: 50-80 parts of polytetrafluoroethylene / reinforced fiber blended fabric, 18-50 parts of resin, and 2-10 parts of modified zinc oxide as described in the above technical solution.

[0044] The raw materials for preparing the UV-ozone aging resistant self-lubricating material provided by the present invention, by weight, include 50-80 parts of polytetrafluoroethylene (PTFE) / reinforcing fiber blended fabric, preferably 55-75 parts, more preferably 60-70 parts, and even more preferably 75 parts. In the present invention, the mass ratio of PTFE to reinforcing fiber in the PTFE / reinforcing fiber blended fabric is preferably 1:0.5-1.8, more preferably 1:0.8-1.5, and even more preferably 1:1-1.2; the reinforcing fiber preferably includes one or more of aramid, glass fiber, carbon fiber, and poly(p-phenylenebenzodioxazole) fiber (PBO), more preferably including aramid, glass fiber, carbon fiber, or PBO fiber; the aramid preferably includes meta-aramid and / or para-aramid. In this invention, the polytetrafluoroethylene / reinforcing fiber blended fabric is preferably obtained by blending polytetrafluoroethylene fibers and reinforcing fibers. The fineness of the polytetrafluoroethylene fibers is preferably 200-600D, more preferably 300-500D, and even more preferably 400-500D. The fineness of the reinforcing fibers is preferably 100-400D, more preferably 150-300D, and even more preferably 200D.

[0045] The raw materials for preparing the UV-ozone aging resistant self-lubricating material provided by the present invention, by weight, include 18 to 50 parts of resin, preferably 20 to 45 parts, more preferably 25 to 40 parts, and even more preferably 30 to 35 parts; the resin preferably includes phenolic resin and / or polyimide resin.

[0046] Based on mass parts, the raw materials for preparing the UV-ozone resistant self-lubricating material provided by the present invention include 2 to 10 parts of the modified zinc oxide described in the above technical solution, preferably 3 to 10 parts, more preferably 5 to 10 parts, and even more preferably 5 to 10 parts.

[0047] This invention provides a method for preparing the UV-ozone resistant self-lubricating material described in the above technical solution, comprising the following steps:

[0048] A self-lubricating fabric impregnation solution is obtained by mixing resin, modified zinc oxide, and organic solvent.

[0049] The polytetrafluoroethylene / reinforced fiber blended fabric is immersed in the self-lubricating fabric impregnation solution and then dried to obtain a pre-impregnated fabric.

[0050] The preimpregnated material is cured to obtain a self-lubricating material resistant to UV-ozone aging.

[0051] This invention mixes resin, modified zinc oxide, and an organic solvent to obtain a self-lubricating fabric impregnation solution. In this invention, the organic solvent is preferably a mixture of ketone, alcohol, and ester solvents; the ketone solvent is preferably acetone; the alcohol solvent is preferably ethanol; and the ester solvent is preferably ethyl acetate. The volume ratio of the ketone, alcohol, and ester solvents in the mixed solvent is preferably 1:0.5–1.5:0.5–1.5, more preferably 1:1:1. The mass ratio of the resin to the volume of the organic solvent is preferably 1g:4–9mL, more preferably 1g:5–8mL, and even more preferably 1g:6–7mL. This invention does not have specific limitations on the mixing process; it is sufficient to ensure that the raw materials are mixed evenly.

[0052] After obtaining the self-lubricating fabric impregnation solution, the present invention impregnates a polytetrafluoroethylene (PTFE) / reinforcing fiber blended fabric in the self-lubricating fabric impregnation solution and then dries it to obtain a pre-impregnated fabric. In the present invention, the PTFE / reinforcing fiber blended fabric is preferably subjected to plasma treatment before use to obtain a plasma-treated PTFE / meta-aramid blended fabric; the power of the plasma treatment is preferably 80-120W, more preferably 100W, the plasma treatment is preferably carried out under vacuum conditions, and the plasma treatment time is preferably 8-15 min, more preferably 10 min. In the present invention, the impregnation is preferably ultrasonic impregnation, the ultrasonic impregnation time is preferably 15-30 min, more preferably 20-25 min, and the present invention does not have a special limitation on the power of the ultrasonic impregnation; ultrasonic power known to those skilled in the art can be used. In the present invention, the drying temperature is preferably 40-60℃, more preferably 50℃, and the drying time is preferably 20-30 min, more preferably 25 min. In this invention, the impregnation and drying steps are repeated. This invention does not have a particular limitation on the number of repetitions. It can increase the weight of the polytetrafluoroethylene / reinforced fiber blend by 10-40% (i.e., the mass ratio of the polytetrafluoroethylene / reinforced fiber blend to the preimpregnated material is 1:1.1-1.4), more preferably by 15-35%, and even more preferably by 20-30%.

[0053] After obtaining the pre-impregnated material, the present invention cures the pre-impregnated material to obtain a self-lubricating material resistant to UV-ozone aging. In the present invention, the curing pressure is preferably 0.1-0.5 MPa, more preferably 0.2-0.4 MPa, and further preferably 0.3 MPa; the curing temperature is preferably 160-190℃, more preferably 170-180℃, and further preferably 175℃; the curing time is preferably 1-2 hours, more preferably 1-1.5 hours. In a specific embodiment of the present invention, the curing is preferably performed by bonding the pre-impregnated material to the surface of a metal substrate before curing; the adhesive used for bonding preferably includes phenolic resin and / or polyimide resin adhesive; the material of the metal substrate preferably includes stainless steel or aerospace metal materials, and the aerospace metal materials preferably include titanium alloys or aluminum alloys.

[0054] This invention also provides the application of the UV-ozone aging-resistant self-lubricating material described in the above-described technical solutions, or the UV-ozone aging-resistant self-lubricating material prepared by the preparation method described in the above-described technical solutions, as a self-lubricating gasket material in aircraft. In this invention, the application in aircraft is preferably in the steering, load-bearing, rotating, or bushing parts of the aircraft, and more preferably includes applications in joint bearings, bushings, or landing gear.

[0055] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0056] Example 1

[0057] (1) According to Figure 1 The flowchart shown illustrates the preparation of modified zinc oxide, with the specific steps as follows:

[0058] Zinc acetate and sodium hydroxide were dissolved in deionized water and magnetically stirred for 20 min. The mixture was then transferred to a reaction vessel and reacted at 160 °C for 10 h. After centrifugation, the resulting solid product was dried at 50 °C to obtain disc-shaped zinc oxide (particle size ≤25 μm). The mass ratio of zinc acetate, sodium hydroxide, and deionized water was 30:1:300.

[0059] The disc-shaped zinc oxide was dispersed in anhydrous ethanol, and silane coupling agent KH570 was added and mixed evenly. The mixture was reacted at 55°C with stirring for 20 h, centrifuged, and the resulting solid product was dried at 80°C to obtain silane coupling agent-grafted zinc oxide. The mass ratio of disc-shaped zinc oxide to silane coupling agent was 1:0.05, and the mass ratio of disc-shaped zinc oxide to the volume ratio of anhydrous ethanol was 1 g:60 mL.

[0060] The silane coupling agent-grafted zinc oxide was dispersed in anhydrous ethanol, and 2-mercaptobenzimidazole and sodium hydroxide were added. The mixture was reacted at 55°C under a nitrogen atmosphere for 20 h. After centrifugation, the resulting solid product was dried at 80°C to obtain modified zinc oxide (ZnO-s-MB). The mass ratio of the silane coupling agent-grafted zinc oxide, 2-mercaptobenzimidazole, and sodium hydroxide was 1:0.08:0.01, and the mass ratio of the silane coupling agent-grafted zinc oxide to the volume ratio of anhydrous ethanol was 1 g:60 mL.

[0061] (2) The polytetrafluoroethylene / meta-aramid blended fabric was plasma-treated for 10 min under vacuum conditions at 100 W to obtain plasma-treated polytetrafluoroethylene / meta-aramid blended fabric; wherein the fineness of the polytetrafluoroethylene fiber is 400D and the fineness of the meta-aramid fiber is 200D.

[0062] 30 parts of phenolic resin were dispersed in a mixed solvent (acetone, ethanol, and ethyl acetate in a volume ratio of 1:1:1), and 4 parts of ZnO-s-MB were added and dispersed evenly to obtain a self-lubricating fabric impregnation solution. 66 parts of plasma-treated polytetrafluoroethylene / meta-aramid blended fabric were placed in the impregnation solution and sonicated for 15 min, and then dried in an oven at 40°C for 20 min. The above impregnation-drying process was repeated until the fabric weight increased by 35% to obtain a pre-impregnated material. The mass ratio of phenolic resin to the volume ratio of the mixed solvent was 1 g: 7 mL.

[0063] The pre-impregnated material was bonded to the surface of a metal substrate with phenolic resin and cured at 0.1 MPa and 160°C for 1 hour to obtain a self-lubricating material resistant to UV-ozone aging.

[0064] Tribological properties of the UV-ozone resistant self-lubricating material: coefficient of friction 0.096, volumetric wear rate 1.27×10⁻⁶. -14 m 3 / N˙m (friction conditions: load is 50.93MPa, rotation speed is 0.203m / s), peel strength is 3.08cN / cm.

[0065] Example 2

[0066] (1) Dissolve zinc acetate and sodium hydroxide in deionized water, stir magnetically for 5 min, transfer to a reaction vessel, react at 100℃ for 26 h, centrifuge, and dry the resulting solid product at 80℃ to obtain disc-shaped zinc oxide (particle size ≤25μm); wherein, the mass ratio of zinc acetate, sodium hydroxide and deionized water is 20:1:200.

[0067] The disc-shaped zinc oxide was dispersed in anhydrous ethanol, and silane coupling agent KH560 was added and mixed evenly. The mixture was reacted at 55°C with stirring for 20 h, centrifuged, and the resulting solid product was dried at 80°C to obtain silane coupling agent-grafted zinc oxide. The mass ratio of disc-shaped zinc oxide to silane coupling agent was 1:0.07, and the mass ratio of disc-shaped zinc oxide to anhydrous ethanol was 1 g:60 mL.

[0068] The silane coupling agent-grafted zinc oxide was dispersed in anhydrous ethanol, and 2-mercaptobenzimidazole and sodium hydroxide were added. The mixture was reacted at 55°C under a nitrogen atmosphere for 20 h. After centrifugation, the resulting solid product was dried at 80°C to obtain modified zinc oxide (ZnO-s-MB). The mass ratio of the silane coupling agent-grafted zinc oxide, 2-mercaptobenzimidazole, and sodium hydroxide was 1:0.07:0.01, and the mass ratio of the silane coupling agent-grafted zinc oxide to the volume ratio of anhydrous ethanol was 1 g:60 mL.

[0069] (2) The polytetrafluoroethylene / meta-aramid blended fabric was plasma-treated for 10 min under vacuum conditions at 100 W to obtain plasma-treated polytetrafluoroethylene / meta-aramid blended fabric; wherein the fineness of the polytetrafluoroethylene fiber is 400D and the fineness of the meta-aramid fiber is 200D.

[0070] Forty parts of phenolic resin were dispersed in a mixed solvent (acetone, ethanol, and ethyl acetate in a volume ratio of 1:1:1), and ten parts of ZnO-s-MB were added and dispersed evenly to obtain a self-lubricating fabric impregnation solution. Fifty parts of plasma-treated polytetrafluoroethylene / meta-aramid blended fabric were placed in the impregnation solution and sonicated for 15 min, then dried in an oven at 40°C for 20 min. The above impregnation-drying process was repeated until the fabric weight increased by 35% to obtain a pre-impregnated material. The mass ratio of phenolic resin to the volume of the mixed solvent was 1 g: 7 mL.

[0071] The pre-impregnated material was bonded to the surface of a metal substrate with phenolic resin and cured at 0.5 MPa and 190°C for 1 hour to obtain a self-lubricating material resistant to UV-ozone aging.

[0072] Tribological properties of the UV-ozone resistant self-lubricating material: coefficient of friction 0.092, volumetric wear rate 1.1×10⁻⁶. -14 m 3 / N˙m (friction conditions: load 48.88MPa, rotational speed 0.169m / s). The UV-ozone resistant self-lubricating material was subjected to UV aging treatment (GBT 16422.3, 96h) and ozone aging treatment (GBT 7762, 100h). The tribological properties of the treated UV-ozone resistant self-lubricating material were: coefficient of friction 0.101, volumetric wear rate 1.3×10⁻⁶. -14m 3 / N˙m (friction conditions: load 48.88MPa, rotational speed 0.169m / s). This indicates that when the ZnO-s-MB addition amount is 10wt%, the wear rate of the material after UV-ozone aging increases by only 18.2%, demonstrating that the UV-ozone resistant self-lubricating material prepared in this invention has excellent UV-ozone aging resistance and wear resistance.

[0073] Comparative Example 1

[0074] The self-lubricating material was prepared according to step (2) of Example 1. The only difference from Example 1 is that ZnO-s-MB was not added to obtain the self-lubricating material.

[0075] The tribological properties of the self-lubricating material are: a coefficient of friction of 0.115 and a volumetric wear rate of 1.73 × 10⁻⁶. -14 m 3 / N˙m (friction conditions: load is 50.93MPa, rotation speed is 0.203m / s), peel strength is 2.68cN / cm.

[0076] By comparing Example 1 and Comparative Example 1, it can be seen that after adding 2 wt% of 2-mercaptobenzimidazole to modify nano zinc oxide, the friction coefficient and wear rate of the material are significantly reduced, and the peel strength is significantly increased. This indicates that 2-mercaptobenzimidazole-modified nano zinc oxide can significantly improve the wear resistance and peel strength of the material. The UV-ozone resistant self-lubricating material prepared by this invention has excellent wear resistance.

[0077] Comparative Example 2

[0078] The self-lubricating pad was prepared according to step (2) of Example 1. The only difference from Example 1 was that 4 parts of ZnO-s-MB were replaced with 4 parts of disc-shaped zinc oxide prepared in Example 1 to obtain the self-lubricating material.

[0079] The tribological properties of the self-lubricating material are: coefficient of friction 0.103, volumetric wear rate 1.54 × 10⁻⁶. -14 m 3 / N˙m (friction conditions: load is 50.93MPa, rotation speed is 0.203m / s), peel strength is 2.89cN / cm.

[0080] By comparing Example 1 and Comparative Example 2, it can be seen that, compared with zinc oxide as a filler, adding 2-mercaptobenzimidazole-modified nano zinc oxide as a filler can significantly reduce the friction coefficient and wear rate of the material and significantly increase the peel strength. This indicates that 2-mercaptobenzimidazole-modified nano zinc oxide can significantly improve the wear resistance and peel strength of the material. The UV-ozone resistant self-lubricating material prepared by this invention has excellent wear resistance.

[0081] Comparative Example 3

[0082] The self-lubricating pad was prepared according to step (2) of Example 1. The only difference from Example 1 was that 4 parts of ZnO-s-MB were replaced with 4 parts of 2-mercaptobenzimidazole to obtain the self-lubricating material.

[0083] The tribological properties of the self-lubricating material are: a coefficient of friction of 0.096 and a volumetric wear rate of 1.61 × 10⁻⁶. -14 m 3 / N˙m (friction conditions: load is 50.93MPa, rotation speed is 0.203m / s), peel strength is 2.90cN / cm.

[0084] By comparing Example 1 and Comparative Example 3, it can be seen that compared with 2-mercaptobenzimidazole filler, the addition of 2-mercaptobenzimidazole modified nano zinc oxide as filler significantly reduces the wear rate and increases the peel strength of the material. This indicates that 2-mercaptobenzimidazole modified nano zinc oxide can significantly improve the wear resistance and peel strength of the material. The UV-ozone resistant self-lubricating material prepared by this invention has excellent wear resistance.

[0085] Comparative Example 4

[0086] The self-lubricating material was prepared according to step (2) of Example 2. The only difference from Example 2 was that 10 parts of ZnO-s-MB were used to replace 2-mercaptobenzimidazole and the disc-shaped zinc oxide prepared in step (1) of Example 2. The total amount of 2-mercaptobenzimidazole and disc-shaped zinc oxide was 10 parts. The mass ratio of disc-shaped zinc oxide to 2-mercaptobenzimidazole was the same as that of disc-shaped zinc oxide to 2-mercaptobenzimidazole in the preparation of ZnO-s-MB in Example 2.

[0087] The tribological properties of the self-lubricating material are: a coefficient of friction of 0.11 and a volumetric wear rate of 1.73 × 10⁻⁶. -14 m 3 / N˙m (friction conditions: load 48.88MPa, rotational speed 0.169m / s). The self-lubricating material was subjected to UV aging treatment (GBT16422.3, 96h) and ozone aging treatment (GBT7762, 100h). The tribological properties of the treated self-lubricating material were: coefficient of friction 0.12, volumetric wear rate 2.01×10⁻⁶. -14 m 3 / N˙m (friction conditions: load 48.88MPa, rotational speed 0.169m / s). This indicates that, compared to adding zinc oxide and 2-mercaptobenzimidazole, the use of 2-mercaptobenzimidazole-modified nano-zinc oxide as a filler in this invention significantly improves the material's resistance to UV-ozone aging and abrasion resistance.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A kind of UV-ozone aging resistant self-lubricating material, comprising the following mass parts of preparation raw materials: polytetrafluoroethylene / reinforced fiber mixed braid 50-80 parts, resin 18-50 parts, modified zinc oxide 2-10 parts; The modified zinc oxide is obtained by modifying zinc oxide grafted with 2-mercapto benzimidazole silane coupling agent;The mass ratio of the zinc oxide grafted with silane coupling agent and 2-mercapto benzimidazole is 1:0.06-0.08; The mass ratio of polytetrafluoroethylene and reinforced fiber in the polytetrafluoroethylene / reinforced fiber mixed braid is 1:0.5-1.8;The reinforced fiber is aramid fiber.

2. The preparation method of the UV-ozone aging resistant self-lubricating material of claim 1, comprising the following steps: Mixing resin, modified zinc oxide and organic solvent to obtain self-lubricating impregnating solution; Placing polytetrafluoroethylene / reinforced fiber mixed braid in the self-lubricating impregnating solution for impregnation and drying to obtain pre-impregnated material; Curing the pre-impregnated material to obtain UV-ozone aging resistant self-lubricating material.

3. The preparation method according to claim 2, characterized in that, The organic solvent is a mixed solvent of ketone solvent, alcohol solvent and ester solvent; The resin comprises phenolic resin and / or polyimide resin; The mass ratio of the resin to the volume of organic solvent is 1g:4-9mL.

4. The production method according to claim 2, characterized by, The mass ratio of the polytetrafluoroethylene / reinforced fiber mixed braid to the pre-impregnated material is 1:1.1-1.

4.

5. The preparation method according to claim 2, characterized in that, The curing pressure is 0.1-0.5MPa, the temperature is 160-190℃, and the time is 1-2h.

6. The application of the UV-ozone aging resistant self-lubricating material of claim 1 or the UV-ozone aging resistant self-lubricating material prepared by the preparation method of any one of claims 2-5 as self-lubricating gasket material in aerospace vehicles.

Images