Wet-type paper-based friction material, preparation method thereof and friction plate

Abstract

The invention relates to the technical field of friction material manufacturing, in particular to a wet-type paper-based friction material, a preparation method thereof and a friction plate. The material comprises a paper base and thermosetting resin formed in the paper base, the thermosetting resin accounts for 20%-40% of the paper base by mass, and micron-sized grooves are formed in the surface of the paper base. The paper base is prepared from the following raw materials: carbon fiber-polyether-ether-ketone composite fiber, reinforced fiber, plant fiber and filler, and the mass part ratio of the carbon fiber-polyether-ether-ketone composite fiber to the reinforced fiber to the plant fiber to the filler is (5-10): (10-15): (25-35): (45-55) based on 100 mass parts of the paper base. The preparation method comprises the following steps: defibering and mixing the paper-based raw materials to form uniform paper-based slurry; conveying the pulp to a forming screen cloth with a micron-sized bulge structure, and carrying out circulating reverse pulse vacuum dehydration to form a paper base with micron-sized grooves in the surface; and finally, immersing the paper base into a thermosetting resin solution, and drying to obtain a finished product. Therefore, under the combined action of the raw materials of the paper base and the thermosetting resin, the wet-type paper-based friction material can maintain the overall mechanical structure at the high temperature, good mechanical performance is guaranteed, and the wet-type paper-based friction material can have good, stable and consistent heat dissipation performance and wear resistance and long service life.

Description

Technical Field

[0001] This application relates to the field of friction material manufacturing technology, and in particular to a wet paper-based friction material, its preparation method, and a friction pad. Background Technology

[0002] Wet paper-based friction materials are friction materials that operate in oil and are widely used in wet braking systems and torque transmission devices in passenger cars, heavy vehicles, and construction machinery. They feature a moderate coefficient of friction, with both dynamic and static friction coefficients approaching 1. The dynamic friction coefficient exhibits minimal variation with linear velocity, and noise levels are low. This material is typically manufactured using a papermaking process, where raw materials such as fibers and friction-modifying fillers are formed into paper, impregnated with resin binders, and dried. Finally, the paper is stamped, bonded, and hot-pressed to form friction pads. Currently, the automotive industry is undergoing a revolutionary shift from traditional gasoline-powered vehicles to electric vehicles. When the electric motor serves as the power source, the clutches of multi-speed gearboxes need to engage at extremely high speed differences. This process generates significant slippage work, which is converted into heat, placing higher demands on the high-temperature resistance of the friction pads made from this material.

[0003] In related technologies, thermal conductivity can be improved not only by curing a base paper made of fiber substrate and filler with thermosetting resin and combining it with carbon-based materials such as carbon fiber and graphite, but also by dispersing plate-shaped graphite particles on the surface of the fiber substrate and having their plate-shaped surfaces intersect with the substrate. This improves heat resistance, increases the coefficient of friction, and maintains a durable and smooth friction surface, while also maintaining positive μ-V characteristics over a wide speed range. However, if the heat resistance depends on the resin matrix, it may decompose or soften at high temperatures, leading to a decrease in the overall mechanical and tribological properties of the material. If a scheme of distributing plate-shaped graphite on the surface of the fiber substrate is adopted, the orientation and stable fixation of the graphite are difficult, the process is complex, and it may also lead to inconsistent thermal conductivity and tribological properties in different directions of the material. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues.

[0005] According to one aspect of this application, a wet paper-based friction material is provided, comprising: The paper base and the thermosetting resin formed in the paper base, wherein the thermosetting resin accounts for 20% to 40% of the mass of the paper base, and the surface of the paper base has micron-level grooves. The raw materials of the paper base include carbon fiber-polyether ether ketone composite fiber, reinforcing fiber, plant fiber and filler; based on 100 parts by weight of the paper base, the mass ratio of the carbon fiber-polyether ether ketone composite fiber, the reinforcing fiber, the plant fiber and the filler is (5~10):(10~15):(25~35):(45~55).

[0006] Compared with existing technologies, the wet paper-based friction material provided in this application includes a paper base and a thermosetting resin formed in the paper base. This thermosetting resin can firmly bond fibers and fillers into a whole. The thermosetting resin in this application accounts for 20% to 40% of the mass of the paper base. Within this parameter range, it enhances the material's mechanical strength and wear resistance, prevents component detachment, and improves structural durability. If the thermosetting resin content is too low, it will lead to weak bonding, a loose material structure, and easy wear; if the thermosetting resin content is too high, it will clog the pores of the paper base, worsening oil flow and heat dissipation. This will not only make the wet paper-based friction material too hard but also reduce heat dissipation, resulting in an excessively low coefficient of friction. Furthermore, the surface of the paper base has micron-level grooves, providing additional flow channels for the oil between the friction pairs. This not only promptly removes the heat generated by friction, preventing localized overheating, but also ensures the uniformity of the oil film distribution, thereby improving the heat dissipation and service life of the wet paper-based friction material. Furthermore, it balances the material's mechanical properties and porosity. This range ensures that the material has both sufficient strength and maintains the necessary permeability.

[0007] Based on this, the paper-based raw materials in this application include carbon fiber-polyetheretherketone (PEEK) composite fibers, reinforcing fibers, plant fibers, and fillers. The PEEK skin of the carbon fiber-PEEK composite fibers can self-repair at high temperatures. Wet friction materials experience frictional performance degradation and are prone to thermal cracking at localized thermal peaks. PEEK exhibits viscoelastic flow during localized heating: under external contact pressure and oil shear force, PEEK, as a micro-bonding phase, moves to the defect area, forming a stable PEEK transfer film, thereby repairing micro-damage, stabilizing the friction coefficient, delaying surface wear, improving durability, and inhibiting friction coefficient degradation at high temperatures. At extreme temperatures, the PEEK skin absorbs a large amount of heat and melts, instantly carrying away heat from the friction surface, providing the system with buffer time. After the skin melts, the carbon fiber participates in the friction process, stabilizing the friction coefficient and extending service life. Simultaneously, carbon fiber is brittle and has weak bonding with other fiber fillers; combining it with PEEK significantly improves the impact resistance, overall strength, and service life of wet paper-based friction materials. The reinforcing fibers in this application improve the mechanical properties of wet paper-based friction materials at high temperatures, giving them better high-temperature resistance. The plant fibers in this application, with their excellent interweaving ability, form a uniform fiber network, providing a stable dispersion carrier for other components and ensuring the molding quality of the paper base. The filler in this application fills the fiber gaps and precisely adjusts the friction and wear performance, ensuring the stability of the friction process. Based on 100 parts by weight of the paper base, when the mass ratio of carbon fiber-polyetheretherketone composite fiber, reinforcing fiber, plant fiber, and filler is (5~10):(10~15):(25~35):(45~55), only a small amount of carbon fiber-polyetheretherketone composite fiber is needed to achieve thermal buffering, stabilize the coefficient of friction, and extend the service life of the wet paper-based friction material, avoiding the impact of excessive addition on the dispersion and interweaving of other components. As a reinforcing component of the paper base structure, the reinforcing fibers, without affecting the function of the carbon fiber-polyetheretherketone composite fiber, improve the mechanical strength and temperature resistance of the paper base with a relatively small proportion. The plant fibers, with a moderate to high proportion, form a fiber-interwoven network that provides a uniformly dispersed carrier for composite fibers, reinforcing fibers, and fillers. This solves the problem of fiber and filler agglomeration and ensures the quality and structural consistency of the paper base. The filler, with the highest proportion, is used to adjust friction and wear properties. It can be uniformly dispersed in the fiber network, and in conjunction with the dispersion process of this application, it can ensure that the friction coefficient of the material is consistent in all directions and that the heat conduction is uniform, avoiding localized high wear or unbalanced heat dissipation.

[0008] Based on this, the combined effect of the paper-based raw materials and thermosetting resin in this application enables the wet paper-based friction material to not only maintain its overall mechanical structure at high temperatures and ensure good mechanical properties, but also to have good, stable and consistent heat dissipation performance, wear resistance and long service life.

[0009] According to another aspect of this application, a method for preparing a wet paper-based friction material is provided, comprising: Carbon fiber-polyetheretherketone composite fiber, reinforcing fiber, plant fiber and filler are loosely mixed to form a uniform paper-based pulp; based on 100 parts of the total solid mass in the paper-based pulp, the mass ratio of the carbon fiber-polyetheretherketone composite fiber, the reinforcing fiber, the plant fiber and the filler is (5~10):(10~15):(25~35):(45~55). The paper-based pulp is fed onto a forming mesh with a micron-level protrusion structure and dewatered by a cyclic reverse pulse vacuum to form a paper base with a uniformly distributed fiber filler having micron-level grooves on the surface. The paper base is immersed in a thermosetting resin solution and dried to form a wet paper-based friction material; the mass of the thermosetting resin accounts for 20% to 40% of the mass of the paper base.

[0010] According to another aspect of this application, a friction pad made of the aforementioned wet paper-based friction material is provided.

[0011] Compared with the prior art, the beneficial effects of the preparation method and friction plate of the wet paper-based friction material provided in this application are the same as those of the aforementioned wet paper-based friction material, and will not be repeated here.

[0012] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description

[0013] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0014] Figure 1 A flowchart illustrating a method for preparing a wet paper-based friction material according to an embodiment of this application is shown; Figure 2 The mesh pattern of Embodiment 1 of this application is shown; Figure 3 The mesh pattern of Embodiment 2 of this application is shown; Figure 4 The mesh pattern of Embodiment 3 of this application is shown. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.

[0016] Wet paper-based friction materials are friction materials that operate in oil and are widely used in wet braking systems and torque transmission devices in passenger cars, heavy vehicles, and construction machinery. They feature a moderate coefficient of friction, with both dynamic and static friction coefficients approaching 1. The dynamic friction coefficient exhibits minimal variation with linear velocity, and noise levels are low. This material is typically manufactured using a papermaking process, where raw materials such as fibers and friction-modifying fillers are formed into paper, impregnated with resin binders, and dried. Finally, the paper is stamped, bonded, and hot-pressed to form friction pads. Currently, the automotive industry is undergoing a revolutionary shift from traditional gasoline-powered vehicles to electric vehicles. When the electric motor serves as the power source, the clutches of multi-speed gearboxes need to engage at extremely high speed differences. This process generates significant slippage work, which is converted into heat, placing higher demands on the high-temperature resistance of the friction pads made from this material.

[0017] In related technologies, wet friction materials without diatomaceous earth can be used, employing a base paper made of fiber substrate and fillers, cured with thermosetting resin, and combined with carbon-based materials such as carbon fiber and graphite to improve thermal conductivity. However, the heat resistance of this technology mainly depends on the resin matrix, which may decompose or soften at high temperatures, leading to a decrease in the overall mechanical and tribological properties of the material. Alternatively, plate-shaped graphite particles can be dispersed on the surface of the fiber substrate, allowing the plate-shaped surfaces to intersect with the substrate, enhancing thermal conductivity and tribological interaction, and maintaining positive μ-V characteristics over a wide speed range. This technique can improve heat resistance, increase the coefficient of friction by rapidly dissipating frictional heat, and simultaneously maintain the durability and smoothness of the friction surface, thereby improving the normal μ-V characteristics. However, if plate-shaped graphite is distributed on the surface of the fiber substrate, the directional distribution and stable fixation of the graphite are difficult, the process is complex, and it may also lead to inconsistent thermal conductivity and tribological properties in different directions of the material.

[0018] To address the aforementioned problems, this application provides a wet paper-based friction material that not only maintains its overall mechanical structure at high temperatures, ensuring good mechanical properties, but also exhibits good, stable, and consistent heat dissipation performance, wear resistance, and a long service life. This wet paper-based friction material comprises a paper base and a thermosetting resin formed within the paper base. The thermosetting resin accounts for 20% to 40% of the mass of the paper base, and the surface of the paper base has micron-level grooves. The raw materials for the paper base include carbon fiber-polyetheretherketone composite fibers, reinforcing fibers, plant fibers, and fillers. Based on 100 parts by mass of the paper base, the mass ratio of carbon fiber-polyetheretherketone composite fibers, reinforcing fibers, plant fibers, and fillers is (5~10):(10~15):(25~35):(45~55).

[0019] Understandably, this thermosetting resin can firmly bond the fibers and fillers into a whole. In this application, the thermosetting resin accounts for 20% to 40% of the paper base mass. Within this range, it enhances the material's mechanical strength and wear resistance, prevents component detachment, and improves structural durability. If the thermosetting resin content is too low, the bonding will be weak, resulting in a loose material structure that is prone to wear; if the thermosetting resin content is too high, it will clog the paper base pores, worsening oil flow and heat dissipation. This will not only make the wet paper-based friction material too hard but also reduce heat dissipation, leading to an excessively low coefficient of friction. Furthermore, the paper base surface has micron-level grooves, providing additional flow channels for the oil between the friction pairs. This not only promptly removes the heat generated by friction, preventing localized overheating, but also ensures the uniformity of the oil film distribution, thereby improving the heat dissipation and service life of the wet paper-based friction material. Moreover, it balances the material's mechanical properties and porosity. This range ensures that the material has sufficient strength while maintaining necessary permeability.

[0020] Based on this, the paper-based raw materials in this application include carbon fiber-polyetheretherketone (PEEK) composite fibers, reinforcing fibers, plant fibers, and fillers. Wet friction materials often experience frictional performance degradation and are prone to thermal cracking at localized thermal peaks. In this application, the PEEK skin of the carbon fiber-PEEK composite fibers exhibits viscoelastic flow during localized heating: under external contact pressure and oil shear force, PEEK, as a micro-bonding phase, moves to the defect area, forming a stable PEEK transfer film to repair micro-damage, thereby stabilizing the friction coefficient, delaying surface wear, improving durability, and inhibiting friction coefficient degradation at high temperatures. At extreme temperatures, the PEEK skin absorbs a large amount of heat and melts, instantly carrying away heat from the friction surface, providing the system with buffer time. After the skin melts, the carbon fiber participates in the friction process, stabilizing the friction coefficient and extending service life. Simultaneously, carbon fiber is brittle and has weak bonding with other fiber fillers; combining it with PEEK significantly improves the impact resistance, overall strength, and service life of wet paper-based friction materials. The reinforcing fibers in this application improve the mechanical properties of wet paper-based friction materials at high temperatures, giving them better high-temperature resistance. The plant fibers in this application, with their excellent interlacing ability, form a uniform fiber network, providing a stable dispersion carrier for other components and ensuring the molding quality of the paper base. The filler in this application fills the fiber gaps and simultaneously regulates friction and wear properties, ensuring the stability of the friction process. Based on 100 parts by weight of the paper base, when the mass ratio of carbon fiber-polyetheretherketone composite fiber, reinforcing fiber, plant fiber, and filler is (5~10):(10~15):(25~35):(45~55), only a small amount of carbon fiber-polyetheretherketone composite fiber is needed to achieve thermal buffering, stabilize the coefficient of friction, and extend the service life of the wet paper-based friction material, avoiding the impact of excessive addition on the dispersion and interlacing of other components. As a reinforcing component of the paper base structure, the reinforcing fibers, without affecting the function of the carbon fiber-polyetheretherketone composite fiber, improve the mechanical strength and temperature resistance of the paper base with a relatively small proportion. The medium to high proportion of plant fibers forms a fiber-interwoven network, providing a uniformly dispersed carrier for composite fibers, reinforcing fibers, and fillers. This solves the problem of fiber and filler agglomeration, ensuring the quality and structural consistency of the paper base. The filler, which has the highest proportion, can be uniformly dispersed in the plant fiber network. Without complex orientation processes, it can ensure consistent friction coefficients and uniform thermal conductivity in all directions, avoiding localized high wear or unbalanced heat dissipation.

[0021] In one alternative embodiment, the thermosetting resin in this application includes at least one of phenolic resin, epoxy resin, polyimide resin and melamine-formaldehyde resin, which can enhance the mechanical strength and wear resistance of the material, prevent component shedding, and improve structural durability.

[0022] In one alternative embodiment, the carbon fiber-polyetheretherketone (PEEK) composite fiber in this application includes a carbon fiber core and a PEEK skin covering the core. This PEEK skin is self-healing at high temperatures. Wet friction materials experience frictional performance degradation and are prone to thermal cracking at localized thermal peaks. PEEK exhibits viscoelastic flow during localized heating: under external contact pressure and oil shear force, PEEK moves as a micro-bonding phase to the defect area, forming a stable PEEK transfer film, thereby repairing micro-damage, stabilizing the friction coefficient, delaying surface wear, improving durability, and inhibiting friction coefficient degradation at high temperatures. At extreme temperatures, the PEEK skin absorbs a large amount of heat and melts, instantly carrying away heat from the friction surface, providing a buffer time for the system. After the skin melts, the carbon fiber participates in the friction process, stabilizing the friction coefficient and extending service life. Simultaneously, carbon fiber is brittle and has weak bonding with other fiber fillers; combining it with PEEK significantly improves the impact resistance, overall strength, and lifespan of wet paper-based friction materials.

[0023] When the mass ratio of polyetheretherketone (PEEK) skin to carbon fiber core is (10~20):(80~90), the 80~90 parts of carbon fiber core, as the main structure of the composite fiber, can fully utilize its core advantages of high strength, high modulus, and stable coefficient of friction, providing basic mechanical support for wet paper-based friction materials. Simultaneously, after the PEEK skin melts, it continues to participate in the friction process, maintaining the stability of the coefficient of friction and avoiding structural weakness or fluctuations in friction performance due to insufficient core content. The 10~20 parts of PEEK skin can completely cover the carbon fiber surface, repairing micro-damage at localized high temperatures, thereby stabilizing the coefficient of friction, delaying surface wear, improving durability, and inhibiting the decline of the coefficient of friction at high temperatures. It also improves the interfacial bonding with other fibers and fillers. Furthermore, it can melt and rapidly absorb heat at extreme temperatures to achieve thermal buffering, and then re-solidify after cooling to complete self-repair. Moreover, it avoids the excessive softening film at high temperatures caused by an excessively high PEEK content, which would lead to a significant decrease in the coefficient of friction and a reduction in the rigidity of the paper-based structure.

[0024] In one alternative embodiment, the reinforcing fibers in this application include at least one of carbon fiber, aramid fiber, and poly(aramid)diazole. These reinforcing fibers can form a reinforcing network within the paper matrix, significantly improving the overall mechanical strength of the material. This allows it to resist damage such as deformation and tearing during friction, maintaining structural stability, especially under high-temperature conditions, and preventing performance collapse due to resin softening or fiber thermal degradation. Furthermore, the high toughness and impact resistance of these fibers can absorb instantaneous impact energy during friction. Combined with the self-healing properties of carbon fiber-polyetheretherketone composite fibers, this strengthens the material's impact resistance, temperature resistance, and durability. Simultaneously, they complement the interwoven network of plant fibers, ensuring material uniformity through the formability of plant fibers while maintaining sufficient strength in the paper matrix after filler filling through their own reinforcing effect.

[0025] In one alternative embodiment, the plant fiber in this application includes at least one of coniferous wood fiber, broadleaf wood fiber, cotton fiber, and flax fiber, which possesses excellent flexibility, branched structure, and high aspect ratio, enabling it to form a relatively dense and uniform three-dimensional fiber network skeleton. This network not only provides a stable and uniform dispersion carrier for the rigid carbon fiber-polyetheretherketone composite fiber, reinforcing fiber, and filler particles, but also effectively prevents component agglomeration and sedimentation, ensuring the uniformity of the paper-based structure, thereby laying the foundation for the consistency of the final friction material performance.

[0026] In one alternative embodiment, the filler in this application includes at least one of graphite, molybdenum disulfide, diatomaceous earth, magnesium oxide, aluminum oxide, calcium sulfate, potassium titanate, and silicon carbide. Graphite and molybdenum disulfide, with their excellent self-lubricating properties, can precisely reduce wear at the friction interface, stabilize the coefficient of friction, and reduce adhesive wear. Porous or sheet-like fillers such as diatomaceous earth and calcium sulfate can fill the gaps in the fiber network, improving the stability of the paper-based structure, while providing storage and flow channels for oil and assisting in heat dissipation. Hard fillers such as magnesium oxide, aluminum oxide, and silicon carbide can increase the coefficient of friction and enhance the wear resistance of the material. Potassium titanate can provide both reinforcement and lubrication. Various fillers can be flexibly combined according to working conditions and uniformly dispersed in the fiber network. Combined with the preparation process of this technology, consistent anisotropic properties of the material can be ensured, avoiding localized wear or heat dissipation imbalance.

[0027] This application also provides a method for preparing a wet paper-based friction material, which can not only maintain good mechanical properties at high or extreme high temperatures, but also have good, stable and consistent heat dissipation performance, wear resistance and long service life. Figure 1 A flowchart illustrating a method for preparing a wet paper-based friction material according to an embodiment of this application is shown. Figure 1 As shown, the preparation method includes: S101: Carbon fiber-polyetheretherketone composite fiber, reinforcing fiber, plant fiber and filler are loosely mixed to form a uniform paper base pulp.

[0028] For example, prior to this step, continuous carbon fibers need to be impregnated in molten polyetheretherketone (PEEK) slurry, cooled, and then cut to form carbon fiber-PEEK composite fibers with a PEEK skin and a carbon fiber core. The molten PEEK fully coats the carbon fiber surface, filling surface defects, and utilizes the thermoplastic properties of PEEK to form a good interface with other components in subsequent processes. Cooling is performed in three stages with controlled temperature: the first stage is 150-200°C with a wind speed of 0.5-1.5 m / s and a length of 5 m; the second stage is 100-150°C with a wind speed of 1-2 m / s and a length of 5 m; and the third stage is 25-100°C with a wind speed of 2-4 m / s and a length of 3 m. This cooling control ensures good dimensional stability of the fiber. The length refers to the effective physical length of each temperature-controlled cooling zone along the continuous production path of the carbon fiber-PEEK composite fiber. Subsequently, it is cut. The cut short composite fibers retain the advantages of high strength and high modulus of carbon fiber, and are endowed with self-healing and thermal buffering functions through polyether ether ketone skin, laying the foundation for the material's subsequent high-temperature stability and friction performance.

[0029] Finally, carbon fiber-polyetheretherketone composite fiber, reinforcing fiber, plant fiber, and filler in a mass ratio of (5~10):(10~15):(25~35):(45~55) are loosened together. Mechanical force breaks up fiber agglomerates, allowing filler particles to be evenly embedded in the fiber network. This avoids performance shortcomings caused by localized enrichment or uneven distribution of a single component, ultimately forming a uniformly composed and structurally stable paper-based pulp. This provides a high-quality substrate for subsequent dewatering and resin impregnation processes, ensuring that the final material meets design requirements for frictional consistency, mechanical strength, and service life.

[0030] It should be understood that the cutting length can be adjusted according to the actual situation, and no limit is set here.

[0031] S102: The paper base slurry is fed onto a forming mesh with a micron-level raised structure and dewatered by a cyclic reverse pulse vacuum to form a paper base with micron-level grooves on the surface.

[0032] For example, prior to this step, a molded mesh with micron-level protrusions needs to be fabricated using coarse and fine threads, based on the optimal heat dissipation path of the oil. The micron-level protrusions are formed by coarse threads with a diameter of 300-500 micrometers, and fine threads with a diameter of 100 micrometers. The mesh size is 80-200 mesh. The mesh structure, designed according to the optimal heat dissipation path of the oil, adds more heat dissipation channels compared to traditional grooves. When the paper-based pulp is laid on the molded mesh, the pulp fills the gaps between the protrusions. After dehydration, the areas corresponding to the protrusions form depressions. The resulting micron-level grooves precisely guide the oil flow, extending the effective heat dissipation path of the oil at the friction interface and preventing uneven heat dissipation caused by localized oil stagnation.

[0033] Furthermore, by conveying the paper-based pulp to a forming mesh with micron-level raised structures, the heat dissipation performance of the wet friction material can be improved at a low cost while ensuring paper uniformity, without the need for additional pattern pressing and etching. In the forming mesh, coarse wires of 300-500 microns serve as the forming carrier for the micron-level raised structures, accurately replicating groove structures with appropriate depth and width, providing ample space for oil flow and heat dissipation. Fine wires of 100 microns are responsible for constructing the basic framework of the mesh, ensuring the stability of the raised structure while avoiding the impact of excessive wire diameter on pulp adhesion and dewatering. Finally, the mesh size range of 80-200 mesh ensures both the density of the mesh, firmly locking in the fibers and fillers in the paper-based pulp to prevent component loss during forming, and the provision of reasonable porosity, providing an efficient channel for subsequent cyclic reverse pulse vacuum dewatering, ensuring uniform pulp dewatering, a relatively dense paper-based structure, and clear and regular groove morphology.

[0034] It should be understood that the optimal heat dissipation path for this oil can be accurately predicted through simulation modeling or verified through actual working conditions. It can be adjusted according to the actual situation and is not limited here.

[0035] For example, in cyclic reverse pulse vacuum dewatering, the vacuum value is -2MPa to -5MPa, the reverse pulse vacuum value is -0.2MPa to -0.5MPa, and the pulse frequency is 2-4Hz. During papermaking, due to the different densities of fiber fillers, heavy fillers tend to settle to the bottom during dewatering, while light fibers float on the surface. After vacuuming, fillers near the mesh are easily removed, resulting in uneven distribution of wet friction paper in the z-direction. Applying small-amplitude, high-frequency vacuum pressure fluctuations in the vacuum chamber, i.e., increasing the reverse change of relative vacuum suction during vacuum dewatering, forms a micro-oscillation-suction dewatering rhythm, preventing fine material bridging and pore reopening without damaging the paper sheet, thereby improving the uniformity of both sides.

[0036] S103: The paper base is immersed in a thermosetting resin solution and dried to form a wet paper-based friction material.

[0037] For example, in the embodiments of this application, the mass of the thermosetting resin accounts for 20% to 40% of the mass of the paper base.

[0038] This application also provides a friction pad made of the aforementioned wet paper-based friction material.

[0039] To verify the effectiveness of the wet paper-based friction material preparation method provided in the embodiments of this application, the following are examples and comparative examples.

[0040] Example 1 The first step involves impregnating continuous carbon fibers in molten polyetheretherketone (PEEK) slurry, cooling it, and then cutting it to form a carbon fiber-PEEK composite fiber with a PEEK skin and a carbon fiber core. Cooling is performed using a three-stage temperature control system: the first stage is 150℃ with a wind speed of 0.5 m / s and a length of 5 m; the second stage is 100℃ with a wind speed of 1 m / s and a length of 5 m; and the third stage is 25℃ with a wind speed of 2 m / s and a length of 3 m.

[0041] Carbon fiber-polyetheretherketone composite fiber, carbon fiber, aramid fiber, polyarylene diazole, softwood fiber, hardwood fiber, cotton fiber, flax fiber, graphite, molybdenum disulfide, diatomaceous earth, magnesium oxide, aluminum oxide, calcium sulfate, potassium titanate, and silicon carbide are loosely mixed to form a homogeneous paper-based pulp. The pulp consists of 5 parts carbon fiber-polyetheretherketone composite fiber, 5 parts carbon fiber, 5 parts aramid fiber, 5 parts polyarylene diazole, 20 parts softwood fiber, 10 parts hardwood fiber, 10 parts graphite, 5 parts molybdenum disulfide, 25 parts diatomaceous earth, 4 parts magnesium oxide, 2 parts aluminum oxide, 2 parts calcium sulfate, 1 part potassium titanate, and 1 part silicon carbide.

[0042] The second step involves feeding the paper-based pulp onto a forming mesh with micron-level raised structures, and then dewatering it using a cyclic reverse-pulse vacuum to form a paper base with micron-level grooves on its surface. During the cyclic reverse-pulse vacuum dewatering, the vacuum value is -2 MPa, the reverse-pulse vacuum value is -0.2 MPa, and the pulse frequency is 4 Hz. The mesh size is 100 mesh, with coarse wire diameter of 300 μm and fine wire diameter of 100 μm. Figure 2 The mesh pattern of Embodiment 1 of this application is shown. Figure 2 As shown, in this embodiment, the paper-based pulp is conveyed with... Figure 2 The mesh fabric with the pattern shown, after being dehydrated, can form a mesh with... Figure 2 The grooves shown are the same size as the thick lines.

[0043] The third step involves immersing the paper base in a thermosetting resin solution and drying and curing it at 20°C to form a wet paper-based friction material. The thermosetting resin comprises 20% of the mass of the paper base.

[0044] Example 2 The first step involves impregnating continuous carbon fibers in molten polyetheretherketone (PEEK) slurry, cooling it, and then cutting it to form a carbon fiber-PEEK composite fiber with a PEEK skin and a carbon fiber core. Cooling is performed using a three-stage temperature control system: the first stage is 200℃ with a wind speed of 1.5 m / s and a length of 5 m; the second stage is 150℃ with a wind speed of 2 m / s and a length of 5 m; and the third stage is 100℃ with a wind speed of 4 m / s and a length of 3 m.

[0045] Carbon fiber-polyetheretherketone composite fiber, carbon fiber, aramid fiber, polyarylene diazole, softwood fiber, hardwood fiber, cotton fiber, flax fiber, graphite, molybdenum disulfide, diatomaceous earth, magnesium oxide, aluminum oxide, calcium sulfate, potassium titanate, and silicon carbide are loosely mixed to form a homogeneous paper-based pulp. The pulp consists of 10 parts carbon fiber-polyetheretherketone composite fiber, 5 parts carbon fiber, 4 parts aramid fiber, 1 part polyarylene diazole, 15 parts softwood fiber, 10 parts cotton fiber, 10 parts flax fiber, 8 parts graphite, 2 parts molybdenum disulfide, 25 parts diatomaceous earth, 5 parts magnesium oxide, 2 parts aluminum oxide, 2 parts calcium sulfate, and 1 part potassium titanate.

[0046] The second step involves feeding the paper-based pulp onto a forming mesh with micron-level raised structures, and then dewatering it using a cyclic reverse-pulse vacuum to form a paper base with micron-level grooves on its surface. During the cyclic reverse-pulse vacuum dewatering, the vacuum value is -5 MPa, the reverse-pulse vacuum value is -0.5 MPa, and the pulse frequency is 2 Hz. The mesh size is 80 mesh, with coarse wire diameter of 400 μm and fine wire diameter of 100 μm. Figure 3 The mesh pattern of Embodiment 2 of this application is shown. Figure 3 As shown, in this embodiment, the paper-based pulp is conveyed with... Figure 3 The mesh fabric with the pattern shown, after being dehydrated, can form a mesh with... Figure 3 The grooves shown are the same size as the thick lines.

[0047] The third step involves immersing the paper base in a thermosetting resin solution and drying and curing it at 20°C to form a wet paper-based friction material. The thermosetting resin comprises 40% of the mass of the paper base.

[0048] Example 3 The first step involves impregnating continuous carbon fibers in molten polyetheretherketone (PEEK) slurry, cooling it, and then cutting it to form a carbon fiber-PEEK composite fiber with a PEEK skin and a carbon fiber core. Cooling is performed using a three-stage temperature control system: the first stage is 180℃ with a wind speed of 1 m / s and a length of 5 m; the second stage is 120℃ with a wind speed of 1.5 m / s and a length of 5 m; and the third stage is 80℃ with a wind speed of 3 m / s and a length of 3 m.

[0049] Carbon fiber-polyetheretherketone composite fiber, carbon fiber, aramid fiber, polyarylene diazole, softwood fiber, hardwood fiber, cotton fiber, flax fiber, graphite, molybdenum disulfide, diatomaceous earth, magnesium oxide, aluminum oxide, calcium sulfate, potassium titanate, and silicon carbide are loosely mixed to form a homogeneous paper-based pulp. The pulp consists of 8 parts carbon fiber-polyetheretherketone composite fiber, 8 parts carbon fiber, 2 parts aramid fiber, 2 parts polyarylene diazole, 20 parts cotton fiber, 5 parts flax fiber, 15 parts graphite, 3 parts molybdenum disulfide, 27 parts diatomaceous earth, 4 parts magnesium oxide, 2 parts aluminum oxide, 2 parts calcium sulfate, 1 part potassium titanate, and 1 part silicon carbide.

[0050] The second step involves feeding the paper-based pulp onto a forming mesh with micron-level raised structures, and then dewatering it using a cyclic reverse-pulse vacuum to form a paper base with micron-level grooves on its surface. During the cyclic reverse-pulse vacuum dewatering, the vacuum value is -3 MPa, the reverse-pulse vacuum value is -0.3 MPa, and the pulse frequency is 3 Hz. The mesh size is 200 mesh, with coarse wire diameter of 500 μm and fine wire diameter of 100 μm. Figure 4 The mesh pattern of Embodiment 3 of this application is shown. Figure 4 As shown, in this embodiment, the paper-based pulp is conveyed with... Figure 4 The mesh fabric with the pattern shown, after being dehydrated, can form a mesh with... Figure 4 The grooves shown are the same size as the thick lines.

[0051] The third step involves immersing the paper base in a thermosetting resin solution and drying and curing it at 20°C to form a wet paper-based friction material. The thermosetting resin comprises 35% of the mass of the paper base.

[0052] Comparative Example 1 The first step involves dissolving and mixing carbon fiber, aramid fiber, polyarylene diazole, softwood fiber, hardwood fiber, cotton fiber, flax fiber, graphite, molybdenum disulfide, diatomaceous earth, magnesium oxide, aluminum oxide, calcium sulfate, potassium titanate, and silicon carbide to form a homogeneous paper-based pulp. The pulp composition is as follows: carbon fiber 10 parts, aramid fiber 5 parts, polyarylene diazole 5 parts, softwood fiber 20 parts, hardwood fiber 10 parts, graphite 10 parts, molybdenum disulfide 5 parts, diatomaceous earth 25 parts, magnesium oxide 4 parts, aluminum oxide 2 parts, calcium sulfate 2 parts, potassium titanate 1 part, and silicon carbide 1 part.

[0053] The second step involves conveying the paper-based pulp to a standard forming wire for vacuum dewatering. The dewatering pressure is -3 MPa.

[0054] The third step involves immersing the paper base in a thermosetting resin solution and drying and curing it at 20°C to form a wet paper-based friction material. The thermosetting resin comprises 20% of the mass of the paper base.

[0055] Comparative Example 2 The first step involves impregnating continuous carbon fibers in molten polyetheretherketone (PEEK) slurry, cooling it, and then cutting it to form a carbon fiber-PEEK composite fiber with a PEEK skin and a carbon fiber core. Cooling is performed using a three-stage temperature control system: the first stage is 150℃ with a wind speed of 0.5 m / s and a length of 5 m; the second stage is 100℃ with a wind speed of 1 m / s and a length of 5 m; and the third stage is 25℃ with a wind speed of 2 m / s and a length of 3 m.

[0056] Carbon fiber-polyetheretherketone composite fiber, carbon fiber, aramid fiber, polyarylene diazole, softwood fiber, hardwood fiber, cotton fiber, flax fiber, graphite, molybdenum disulfide, diatomaceous earth, magnesium oxide, aluminum oxide, calcium sulfate, potassium titanate, and silicon carbide are loosely mixed to form a homogeneous paper-based pulp. The pulp consists of 8 parts carbon fiber-polyetheretherketone composite fiber, 8 parts carbon fiber, 2 parts aramid fiber, 2 parts polyarylene diazole, 20 parts cotton fiber, 5 parts flax fiber, 15 parts graphite, 3 parts molybdenum disulfide, 27 parts diatomaceous earth, 4 parts magnesium oxide, 2 parts aluminum oxide, 2 parts calcium sulfate, 1 part potassium titanate, and 1 part silicon carbide.

[0057] The second step involves conveying the paper-based pulp to a standard forming wire for vacuum dewatering. The dewatering pressure is -3 MPa.

[0058] The third step involves immersing the paper base in a thermosetting resin solution and drying and curing it at 20°C to form a wet paper-based friction material. The thermosetting resin comprises 35% of the mass of the paper base.

[0059] The fourth step involves assembling the impregnated paper base into a friction pad. A 55nm picosecond fiber laser is then used to micro-etch the surface of the friction pad paper base using the micro-morphology of the coarse lines in Reference Example 1, forming micro-oil grooves. The overall processing time for a single friction pad is 90 seconds.

[0060] To better compare the performance of the embodiments and comparative examples, the above-mentioned wet paper-based friction material was patched and hot-pressed into a friction sheet.

[0061] Next, the friction plates in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to performance tests. The friction performance was tested according to GB / T 35472.6 Test Method for Friction Elements of Wet Automatic Transmissions; with reference to JB / T7909-2011 Test Method for Friction Performance of Wet Sintered Metal Friction Materials, with speed and inertia as constant values, the pressure was increased to shorten the engagement time and increase the average power density. If the friction pair still did not fail after the test, the energy density and average power density could be further increased under the condition that other parameters remained unchanged, and the next level of test could be carried out until failure was observed. The appearance of failure characteristics was observed. The uniformity of the wet friction paper was observed visually and under a microscope. The impact resistance was judged by observing whether the friction material showed delamination, cracks, etc., using a drop hammer impact test.

[0062] Table 1 shows the performance parameters of Examples 1 to 3 and Comparative Examples 1 to 2.

[0063] Table 1

[0064] As shown in Table 1, compared to Comparative Example 1, the dynamic and static friction coefficients of Examples 1 to 3 of this application all exhibit narrow-range fluctuations, indicating good paper base uniformity. This demonstrates that the friction pads made from the wet paper-based friction materials of Examples 1 to 3, which undergo cyclic anti-pulse vacuum dehydration, exhibit stable friction performance and good paper base uniformity. Furthermore, a higher energy load failure level indicates a higher energy load that can be withstood. The energy load failure levels of Examples 1 to 3 reach level 6, far exceeding level 4 of Comparative Example 1 and level 5 of Comparative Example 2. The material exhibits minimal or no visible failure characteristics, indicating that it can withstand higher energy impacts without failure and has good heat dissipation. Although Comparative Example 2 has the same groove pattern as Example 1, the burrs at the groove edges generated after laser etching affect heat dissipation. Examples 1 to 3 also demonstrate good impact resistance. This is the result of the combined effects of carbon fiber-polyetheretherketone, the molded mesh with micron-level protrusions, reinforcing fibers, and thermosetting resin. Comparative Example 2 uses laser etching to create micro-morphology, which can achieve trenches but is complex, time-consuming, and costly. Examples 1 to 3, on the other hand, use a shaped mesh with micron-level protrusions and a cyclic reverse pulse vacuum dehydration process, which is simple, cost-controllable, and has better heat dissipation performance.

[0065] The above description is merely a specific embodiment of this application. Obviously, various modifications and combinations can be made without departing from the spirit and scope of this application. Accordingly, this specification and accompanying drawings are merely exemplary descriptions of this application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and modifications of this application fall within the scope of the claims of this application and their equivalents, the intent of this application includes these modifications and modifications. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the stated claims. It should also be noted that in the apparatus and method of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalent solutions of this application. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be applied within the widest scope consistent with the principles and novel features disclosed herein. The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although several exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A wet paper-based friction material, characterized by, The paper base and the thermosetting resin formed in the paper base, the mass of the thermosetting resin accounts for 20%~40% of the mass of the paper base, the surface of the paper base has microscale grooves; The raw material of the paper base includes carbon fiber-polyether ether ketone composite fiber, reinforcing fiber, plant fiber and filler; the mass ratio of the carbon fiber-polyether ether ketone composite fiber, the reinforcing fiber, the plant fiber and the filler is (5~10):(10~15):(25~35):(45~55) based on 100 parts of the mass of the paper base. The carbon fiber-polyether ether ketone composite fiber includes a carbon fiber core layer and a polyether ether ketone skin layer coated on the core layer; the mass ratio of the polyether ether ketone skin layer and the carbon fiber core layer is (10~20):(80~90).

2. The wet paper-based friction material of claim 1, wherein The reinforcing fiber includes at least one of carbon fiber, aramid fiber and polyaryl oxadiazole.

3. The wet paper-based friction material of claim 1, wherein The plant fiber includes at least one of coniferous wood fiber, broadleaf wood fiber, cotton fiber and flax fiber.

4. The wet paper-based friction material of claim 1, wherein The filler includes at least one of graphite, molybdenum disulfide, diatomite, magnesium oxide, aluminum oxide, calcium sulfate, potassium titanate and silicon carbide.

5. The wet paper-based friction material according to any one of claims 1 to 4, wherein The paper base and the thermosetting resin formed in the paper base, the mass of the thermosetting resin accounts for 20%~40% of the mass of the paper base, the surface of the paper base has microscale grooves; 6. A method of producing the wet paper-based friction material according to any one of claims 1 to 5, characterized by, The paper base is immersed in a thermosetting resin solution, and after drying, a wet paper base friction material is formed; the mass of the thermosetting resin accounts for 20%~40% of the mass of the paper base. Before the carbon fiber-polyether ether ketone composite fiber, the reinforcing fiber, the plant fiber and the filler are defibrated and mixed, the preparation method further includes: The continuous carbon fiber is immersed in molten polyether ether ketone slurry, and after cooling, it is cut to form a carbon fiber-polyether ether ketone composite fiber with a skin layer of polyether ether ketone and a core layer of carbon fiber. In the circulating reverse pulse vacuum dewatering, the vacuum value is-2MPa~-5MPa, the reverse pulse vacuum value is-0.2MPa~-0.5MPa, and the pulse frequency is 2-4Hz.

7. The method of making a wet paper-based friction material of claim 6, wherein, Before the paper base slurry is transported to the forming screen cloth with microscale convex structure, the preparation method further includes: A forming screen cloth with microscale convex structure is made by using thick lines and thin lines; the microscale convex structure is formed by the thick lines, the diameter of the thick lines is 300 microns~500 microns, and the diameter of the thin lines is 100 microns.

8. The method of claim 6, wherein the wet paper-based friction material is prepared by the steps of:

10. A friction plate made of the wet paper base friction material of any one of claims 1~5.

9. The method of making a wet paper-based friction material of claim 6, wherein, ​ ​ ​

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