Friction material and preparation method thereof, brake pad and preparation method thereof, brake disc and vehicle

Abstract

The invention discloses a friction material and a preparation method thereof, a brake pad and a preparation method thereof, a brake disc and a vehicle, the friction material comprises a first fiber, the first fiber comprises an aramid fiber, and the aramid fiber comprises an aramid fiber body; the wrapping layer covers at least part of the surface of the aramid fiber body, and the wrapping layer comprises nitrile rubber. The friction material has high damping performance and good hardness, the hardness stability at different temperatures is high, noise generated during friction is low, wear resistance and heat resistance are high, and the service life is long.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of brake pads. Specifically, the present application relates to a friction material and a preparation method thereof, a brake pad and a preparation method thereof, a brake disc and a vehicle. BACKGROUND

[0002] With the rapid development of domestic new energy automobile industry and the continuous rise of residents' disposable income, the number of China's car ownership is rising. When choosing to buy a car, consumers are increasingly demanding driving comfort. Noise is easily produced during driving, and the hardness of the brake pad will increase at low temperature, and the damping coefficient will decrease. Noise at low temperature is a long-term problem that has plagued major automobile manufacturers.

[0003] Noise is generated by friction between the brake pad and the brake disc, and the causes are very complex. In terms of brake pads, the composition of the friction material is the most important cause of brake noise. The greater the friction coefficient and hardness of the friction material, the more likely it is to produce noise during driving. At low temperatures, the hardness of the friction material will increase, the damping effect of the sound-absorbing sheet will decrease, and the probability of noise will greatly increase. SUMMARY

[0004] The present application aims to at least partially solve one of the problems in the related art. To this end, one object of the present application is to provide a friction material and a preparation method thereof, a brake pad and a preparation method thereof, a brake disc and a vehicle. The brake pad of the present application has high damping performance and good hardness, strong hardness stability at different temperatures, low noise during braking, strong wear resistance and heat resistance, and high service life.

[0005] The present application provides a friction material. According to an embodiment of the present application, the friction material comprises: a first fiber, the first fiber comprising aramid fiber, the aramid fiber comprising: an aramid fiber body; a coating layer covering at least part of the surface of the aramid fiber body, the coating layer comprising nitrile rubber.

[0006] According to the friction material of the embodiment of the present application, the aramid fiber serves as a skeleton in the friction material, and the nitrile rubber serves as a damping material in the friction material, playing a role of noise reduction. By coating the nitrile rubber on the aramid fiber, the dispersibility of the nitrile rubber is enhanced, and the stability of the spatial structure is improved, so that the influence of the change of the environmental temperature on the hardness of the nitrile rubber is effectively reduced, and the friction material can maintain stable hardness under various temperature environmental conditions, especially under low temperature environmental conditions. The nitrile rubber is attached to the surface of the aramid fiber to form a composite damping structure, in which the deformation of the rubber is effectively limited by the aramid fiber, the energy absorption capacity of the rubber is enhanced, the damping performance of the friction material is improved, and the conversion of the energy generated by friction into sound energy is effectively reduced, so that the noise is significantly reduced.

[0007] According to the embodiment of the present application, the friction material can further have the following additional technical features:

[0008] According to the embodiment of the present application, the thickness of the coating layer is 1 μm to 7 μm.

[0009] And / or, the volume of the aramid fiber is 8 to 12 times the volume of the aramid fiber body.

[0010] According to the embodiment of the present application, the thickness of the coating layer is 3 μm to 5 μm.

[0011] According to the embodiment of the present application, the first fiber further includes at least one of copper fiber and steel fiber.

[0012] According to the embodiment of the present application, the first fiber further includes copper fiber and steel fiber, and the first fiber includes, based on the total weight of the friction material:

[0013] 1 to 4 parts of the aramid fiber;

[0014] 5 to 10 parts of copper fiber;

[0015] 20 to 30 parts of steel fiber.

[0016] According to the embodiment of the present application, the friction material further includes a first adhesive, and the first adhesive includes a phenolic resin.

[0017] According to the embodiment of the present application, the phenolic resin is selected from a phenolic resin modified by nitrile rubber and / or boric acid.

[0018] According to the embodiment of the present application, based on the total weight of the friction material, the friction material includes: 1 to 4 parts of the aramid fiber and 9 to 20 parts of the first adhesive; or 1 to 4 parts of the aramid fiber and 11 to 17 parts of the first adhesive.

[0019] According to embodiments of this application, the first adhesive further comprises at least one of butyl rubber and a coupling agent;

[0020] The coupling agent includes silane coupling agents and / or titanate coupling agents.

[0021] According to an embodiment of this application, based on the total weight of the friction material, the first adhesive comprises:

[0022] 6 to 12 parts of the phenolic resin;

[0023] 2 to 5 parts of nitrile rubber;

[0024] 1 to 3 parts of coupling agent.

[0025] According to embodiments of this application, the friction material further includes a friction modifier, which includes at least one of iron powder, copper powder, graphite, vermiculite, molybdenum disulfide, zinc oxide, and aluminum oxide.

[0026] According to an embodiment of this application, based on the total weight of the friction material, the friction material comprises: 1 to 4 parts of the aramid fiber and 32 to 66 parts of the friction modifier; or, 1 to 4 parts of the aramid fiber and 38 to 51 parts of the friction modifier;

[0027] And / or, the friction modifier comprises iron powder, copper powder, graphite, vermiculite, molybdenum disulfide, zinc oxide, and aluminum oxide. Based on the total weight of the friction material, the friction modifier comprises: 10-15 parts copper powder, 5-10 parts iron powder, 5-10 parts graphite, 5-10 parts vermiculite, 3-8 parts molybdenum disulfide, 2-8 parts zinc oxide, and 2-5 parts aluminum oxide.

[0028] According to an embodiment of this application, the pH value of the friction material is 6.0 to 7.0, and the friction material further includes a pH adjuster, which includes calcium hydroxide.

[0029] According to an embodiment of this application, based on the total weight of the friction material, the friction material comprises: 1 to 4 parts of the aramid fiber and 2 to 4 parts of the pH adjuster; or, 1 to 4 parts of the aramid fiber and 2 to 4 parts of the pH adjuster.

[0030] According to an embodiment of this application, based on the total weight of the friction material, the friction material comprises:

[0031] 26 to 44 parts of a first fiber, the first fiber comprising: 1 to 4 parts of the aramid fiber, 5 to 10 parts of copper fiber and 20 to 30 parts of steel fiber;

[0032] 9 to 20 parts of a first adhesive, the first adhesive comprising: 6 to 12 parts of phenolic resin, 2 to 5 parts of nitrile rubber and 1 to 3 parts of coupling agent;

[0033] 32 to 66 parts of friction modifier, wherein the friction modifier comprises: 10 to 15 parts of copper powder, 5 to 10 parts of iron powder, 5 to 10 parts of graphite, 5 to 10 parts of vermiculite, 3 to 8 parts of molybdenum disulfide, 2 to 8 parts of zinc oxide and 2 to 5 parts of aluminum oxide;

[0034] 2 to 4 parts of pH adjuster, wherein the pH adjuster includes calcium hydroxide.

[0035] A second aspect of this application discloses a method for preparing the friction material described in the first aspect. According to an embodiment of this application, the method includes: preparing the aramid fiber, wherein the method for preparing the aramid fiber includes: placing the aramid fiber body in a nitrile rubber latex, mixing, and then drying the resulting mixture to obtain the aramid fiber.

[0036] According to embodiments of this application, the concentration of the nitrile rubber latex is 5wt% to 15wt%; and / or, the aramid fiber body is placed in the nitrile rubber latex for 1h to 2h; and / or, the drying treatment temperature is 50℃ to 80℃ and the time is 40min to 90min.

[0037] According to embodiments of this application, the concentration of the nitrile rubber latex is 8wt% to 12wt%; and / or, the aramid fiber body is placed in the nitrile rubber latex for 1.3h to 1.7h.

[0038] According to an embodiment of this application, the method further includes: stirring at least one of the first adhesive, friction modifier, and pH modifier with the first fiber to obtain the friction material;

[0039] The stirring speed is 600-1000 r / min, and / or the stirring time is 10-30 min.

[0040] A third aspect of this application discloses a brake pad. According to an embodiment of this application, the brake pad comprises: a substrate;

[0041] A friction layer disposed on at least a portion of the surface of the substrate, the friction layer comprising the friction material described in the first aspect.

[0042] According to embodiments of this application, the porosity of the friction layer is 10% to 25%;

[0043] And / or, at 25°C, the Rockwell hardness of the friction layer is 60-75;

[0044] And / or, at -20°C, the Rockwell hardness of the friction layer is 65 to 90;

[0045] And / or, the thickness of the friction layer is 5cm to 9cm.

[0046] According to an embodiment of this application, the brake pad further includes: an adhesive layer disposed between the substrate and the friction layer;

[0047] The adhesive layer includes an adhesive material, which includes a second adhesive, a second fiber, and a filler.

[0048] According to an embodiment of this application, the second adhesive includes at least one of phenolic resin and nitrile rubber;

[0049] And / or, the second fiber includes at least one of aramid fiber, steel fiber and mineral fiber;

[0050] And / or, the filler comprises at least one of barium sulfate, vermiculite, graphite, zinc oxide, and calcium fluoride;

[0051] And / or, based on the total weight of the adhesive material, the adhesive material comprises:

[0052] 10-28 parts of a second adhesive, 27-50 parts of a second fiber, and 34-68 parts of a filler; or, 15-20 parts of a second adhesive, 30-40 parts of a second fiber, and 45-55 parts of a filler;

[0053] And / or, the thickness of the adhesive layer is 1cm to 3cm.

[0054] A fourth aspect of this application discloses a method for preparing the brake pads described in the third aspect. According to an embodiment of this application, the method includes:

[0055] The friction material and the substrate are subjected to molding treatment to obtain a molded blank;

[0056] The molded blank is cured to form the friction layer on at least a portion of the surface of the substrate, thereby obtaining the brake pad.

[0057] According to embodiments of this application, the method further includes:

[0058] The friction material, the adhesive material, and the substrate are subjected to molding to obtain the molded blank.

[0059] The molded blank is cured to form the adhesive layer and friction layer sequentially on at least a portion of the surface of the substrate, thereby obtaining the brake pad.

[0060] According to an embodiment of this application, the molding temperature is 140°C to 170°C;

[0061] And / or, the pressure of the molding process is 20 MPa to 50 MPa;

[0062] And / or, the molding process takes 3 to 10 minutes;

[0063] And / or, the curing process includes a first heat treatment and a second heat treatment, satisfying at least one of the following conditions:

[0064] The temperature of the first heat treatment is 155℃~170℃;

[0065] The first heat treatment lasts for 4 to 8 hours;

[0066] The temperature of the second heat treatment is 200℃~250℃;

[0067] The second heat treatment lasts for 3 to 5 hours.

[0068] A fifth aspect of this application discloses a brake disc. According to an embodiment of this application, the brake disc includes the brake pads described in the third aspect of this application.

[0069] A sixth aspect of this application discloses a vehicle. According to an embodiment of this application, the vehicle includes: the brake pads described in the third aspect of this application or the brake disc described in the fifth aspect.

[0070] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0071] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0072] Figure 1 A schematic diagram of a brake pad structure is shown;

[0073] Figure 2 A flowchart of a method for preparing brake pads is shown;

[0074] Figure 3 The image shown is a physical photograph of the aramid fiber coated with nitrile rubber according to Example 2 of this application;

[0075] Figure 4 The image shown is an electron microscope image of aramid fibers coated with nitrile rubber according to Example 2 of this application.

[0076] Figure label:

[0077] 100: Substrate; 200: Friction layer; 300: Adhesive layer; 400: Sound-absorbing sheet. Detailed Implementation

[0078] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0079] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0080] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this application.

[0081] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0082] This application provides a friction material in its first aspect. According to an embodiment of this application, the friction material includes: a first fiber, the first fiber comprising aramid fiber, the aramid fiber comprising: an aramid fiber body; and a coating layer covering at least a portion of the surface of the aramid fiber body, the coating layer comprising nitrile rubber.

[0083] According to the friction material of this application embodiment, aramid fibers act as the skeleton, while nitrile rubber acts as the damping material, playing a role in noise reduction. By coating aramid fibers with nitrile rubber, not only is the dispersion of nitrile fibers enhanced, but the stability of its spatial structure is also improved, effectively mitigating the influence of environmental temperature changes on the hardness of nitrile rubber. This allows the friction material to maintain stable hardness under various environmental temperature changes, and it still has high damping performance even at low temperatures, resulting in better vibration reduction and noise reduction effects. Nitrile rubber adheres to the surface of aramid fibers, forming a composite damping structure. In this structure, the presence of aramid fibers effectively restricts the deformation of nitrile rubber, enhances its energy absorption capacity, thereby improving the damping performance of the friction material and effectively reducing the conversion of energy generated by friction into sound energy, thus significantly reducing noise generation.

[0084] According to embodiments of this application, the thickness of the coating layer is 1 μm to 7 μm. Exemplarily, the thickness of the coating layer is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, or 7 μm, preferably 3 μm to 5 μm. This further enhances the stability of the nitrile fiber and mitigates the impact of environmental temperature changes on the hardness of the nitrile rubber. Additionally, it further restricts the deformation of the nitrile rubber, enhances its energy absorption capacity, and thus improves the damping performance of the friction material, resulting in better vibration reduction and noise reduction effects. Furthermore, the coating layer can stably coat the surface of the aramid fiber and is not easily detached.

[0085] According to embodiments of this application, the volume of the aramid fiber is 8 to 12 times the volume of the aramid fiber body. Exemplarily, the volume of the aramid fiber is 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, or 12 times the volume of the aramid fiber body. This facilitates the formation of a uniform coating layer of nitrile rubber on the aramid fiber body, and the coating layer is less prone to peeling off.

[0086] According to embodiments of this application, the first fiber further comprises at least one of copper fiber and steel fiber. Steel and copper fibers can enhance the mechanical strength of the friction material, thereby improving its structural stability and impact resistance. They also help absorb and dissipate energy, reducing noise and vibration. Additionally, copper fiber, as a thermal conductor, can quickly disperse the heat generated by friction, improving heat resistance.

[0087] According to an embodiment of this application, based on the total weight of the friction material, the first fiber comprises:

[0088] 1 to 4 parts of the aramid fiber, for example, 1 part, 2 parts, 3 parts, or 4 parts;

[0089] 5 to 10 parts of copper fiber, for example, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts;

[0090] 20-30 parts steel fiber. For example, 20 parts, 22 parts, 24 parts, 25 parts, 26 parts, 28 parts, and 30 parts.

[0091] Using the above-mentioned ratio of aramid fiber, copper fiber and steel fiber can further give the friction material suitable hardness, stable structural strength, and prevent premature wear and structural loosening. It can maintain relatively stable hardness under different temperature conditions, so that the friction material can maintain stable hardness under changes in ambient temperature. Even at low temperature conditions, it still has high damping performance, good vibration reduction and noise reduction effect, thus providing a consistent braking effect under various temperature environments. It can also further reduce the noise generated by the friction material during braking.

[0092] According to embodiments of this application, the friction material further includes a first adhesive, which comprises a phenolic resin. The phenolic resin readily bonds to other components in the friction material, providing stable adhesion. Furthermore, the phenolic resin exhibits good thermal stability, wear resistance, and corrosion resistance, extending the service life of the friction material and maintaining its performance under harsh environmental conditions.

[0093] According to embodiments of this application, the phenolic resin is selected from nitrile rubber modified and / or boric acid modified phenolic resins. Modifying the phenolic resin with nitrile rubber can improve its thermal properties, enhance its damping performance, and better perform its noise reduction and vibration damping functions. Modifying the phenolic resin with boric acid is beneficial for improving the heat resistance and damping performance of the friction material, reducing the decrease in the coefficient of friction due to temperature rise during friction, resulting in high mechanical strength, suitable hardness, strong durability, and extended service life. Among these modifications, the combined modification method of nitrile rubber modification and boric acid modification is even more effective. Exemplarily, a method for modifying phenolic resin includes: mixing at least one of rubber and boric acid with the phenolic resin in a intensive kneading process, followed by crushing and sieving to obtain the modified phenolic resin.

[0094] According to an embodiment of this application, based on the total weight of the friction material, the friction material comprises:

[0095] The aramid fiber consists of 1 to 4 parts, for example, 1 part, 2 parts, 3 parts, or 4 parts;

[0096] The first adhesive is 9 to 20 parts, for example, 9, 10, 11, 12, 14, 15, 17, 18, 19, or 20 parts, preferably 11 to 17 parts.

[0097] According to embodiments of this application, the first adhesive further comprises at least one of butyl rubber and a coupling agent. Nitrile rubber acts as a damping material, reducing noise. Furthermore, nitrile rubber possesses excellent elasticity and oil resistance, enhancing the friction performance and wear resistance of the friction material. The coupling agent can strengthen the adhesion between the components, improving the stability of the friction material structure.

[0098] According to embodiments of this application, the coupling agent comprises a silane coupling agent and / or a titanate coupling agent. Exemplarily, the coupling agent includes γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), γ-aminopropyltriethoxysilane (KH550), and γ-methacryloyloxypropyl (KH570). This improves the adhesion of the friction material, enhancing not only its mechanical properties and thermal stability but also its processability and resistance to chemical corrosion.

[0099] According to embodiments of this application, the acrylonitrile content of the nitrile rubber is 25% to 30% by mass. Exemplarily, the acrylonitrile content of the nitrile rubber is 25%, 26%, 27%, 28%, 29%, or 30% by mass. Therefore, the nitrile rubber exhibits excellent oil and chemical resistance while maintaining good elasticity and flexibility, improving the stability and durability of the friction material over a wide temperature range and enhancing its applicability in various temperature environments.

[0100] According to an embodiment of this application, based on the total weight of the friction material, the first adhesive comprises:

[0101] The phenolic resin is 6 to 12 parts, for example, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, or 12 parts;

[0102] 2 to 5 parts of nitrile rubber, for example, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, and 5 parts;

[0103] The coupling agent can be 1 to 3 parts, for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts.

[0104] Using the above-mentioned proportions can give the friction material more suitable bonding strength and hardness, stable structural strength, and prevent premature wear and structural loosening. Furthermore, it can further improve noise reduction and enhance the friction performance and wear resistance of the friction material.

[0105] According to embodiments of this application, the friction material further includes a friction modifier, which includes at least one of iron powder, copper powder, graphite, vermiculite, molybdenum disulfide, zinc oxide, and aluminum oxide.

[0106] By adding the aforementioned substances to friction materials, the frictional properties of the materials can be improved. Specifically, iron powder can quickly disperse the heat generated by friction, improving the heat resistance of the friction material; it also has filling and dispersing properties to increase the density and consistency of the friction material, thereby quickly dispersing the heat generated during friction and reducing hot spots and thermal fade. Simultaneously, it can enhance the mechanical strength and wear resistance of the material, extending the service life of brake pads. Copper powder, as a thermal conductor, helps to quickly disperse the heat generated by friction, preventing localized overheating. Graphite provides lubrication, reducing the coefficient of friction and decreasing wear. Vermiculite expands at high temperatures, contributing to heat insulation and noise reduction. Molybdenum disulfide has good lubricity and wear resistance, maintaining frictional stability at high temperatures. Zinc oxide can improve the processing performance and thermal stability of friction materials. Aluminum oxide can increase the hardness and wear resistance of friction materials.

[0107] According to embodiments of this application, the particle size of the iron powder is 0.5 μm to 1 μm. Exemplarily, the particle size of the iron powder is 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1 μm. This results in better filling and dispersibility, improving the density and consistency of the friction material, thereby rapidly dispersing the heat generated during friction and reducing hot spots and thermal fade. Simultaneously, it also enhances the mechanical strength and wear resistance of the material, extending the service life of the brake pads.

[0108] According to embodiments of this application, the graphite particle size is 500 μm to 900 μm. Exemplarily, the graphite particle size is 500 μm, 600 μm, 700 μm, 800 μm, or 900 μm. This helps to uniformly disperse the graphite in the material, thereby improving overall frictional stability and performance consistency; furthermore, it provides a stable coefficient of friction at high temperatures, ensuring that braking performance is not affected by temperature changes; further still, it can reduce wear during friction, extending the service life of brake pads; simultaneously, it helps to improve the thermal conductivity of the material, helping to disperse the heat generated by friction and preventing localized overheating.

[0109] According to an embodiment of this application, based on the total weight of the friction material, the friction material comprises:

[0110] The aramid fiber consists of 1 to 4 parts, for example, 1 part, 2 parts, 3 parts, or 4 parts;

[0111] The friction modifier is in the range of 32 to 66 parts, for example, 32 parts, 35 parts, 38 parts, 40 parts, 45 parts, 50 parts, 51 parts, 55 parts, 60 parts, 65 parts, or 66 parts, preferably 38 to 51 parts.

[0112] Therefore, using the above ratio can further improve the friction performance of friction materials, such as noise reduction, vibration reduction, improved structural stability, thermal stability, wear resistance and corrosion resistance.

[0113] According to embodiments of this application, the friction modifier comprises iron powder, copper powder, graphite, vermiculite, molybdenum disulfide, zinc oxide, and aluminum oxide. Based on the total weight of the friction material, the friction modifier comprises: 10-15 parts of copper powder (e.g., 10, 11, 12, 13, 14, or 15 parts), 5-10 parts of iron powder (e.g., 5, 6, 7, 8, 9, or 10 parts), and 5-10 parts of... The composition comprises: graphite (e.g., 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts), vermiculite (e.g., 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts), molybdenum disulfide (e.g., 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts), zinc oxide (e.g., 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts), and aluminum oxide (e.g., 2 parts, 3 parts, 4 parts, 5 parts). Therefore, using the above proportions can further improve the friction properties of the friction material, such as noise reduction, vibration damping, improved structural stability, thermal stability, wear resistance, and corrosion resistance.

[0114] According to embodiments of this application, the friction material has a pH value of 6.0 to 7.0, and the friction material further includes a pH adjuster, which includes calcium hydroxide. This prevents the friction material from rusting.

[0115] According to an embodiment of this application, based on the total weight of the friction material, the friction material comprises: 1 to 4 parts of the aramid fiber and 2 to 4 parts of the pH adjuster; or, 1 to 4 parts of the aramid fiber and 2 to 4 parts of the pH adjuster. This facilitates adjusting the pH value of the friction material to 6.0 to 7.0.

[0116] According to an embodiment of this application, based on the total weight of the friction material, the friction material comprises:

[0117] 26 to 44 parts of a first fiber, the first fiber comprising: 1 to 4 parts of the aramid fiber, 5 to 10 parts of copper fiber and 20 to 30 parts of steel fiber;

[0118] 9 to 20 parts of a first adhesive, the first adhesive comprising: 6 to 12 parts of phenolic resin, 2 to 5 parts of nitrile rubber and 1 to 3 parts of coupling agent;

[0119] 32 to 66 parts of friction modifier, wherein the friction modifier comprises: 10 to 15 parts of copper powder, 5 to 10 parts of iron powder, 5 to 10 parts of graphite, 5 to 10 parts of vermiculite, 3 to 8 parts of molybdenum disulfide, 2 to 8 parts of zinc oxide and 2 to 5 parts of aluminum oxide;

[0120] 2 to 4 parts of pH adjuster, wherein the pH adjuster includes calcium hydroxide.

[0121] Therefore, the friction material with the above composition has high damping performance, good vibration reduction and noise reduction effect; strong thermal stability, stable structure, and little influence of environmental temperature changes on the hardness of nitrile rubber, so that the friction material can maintain stable hardness under various environmental temperature changes, especially under low temperature conditions; it has wear resistance, corrosion resistance and durability, and long service life.

[0122] The second aspect of this application discloses a method for preparing the friction material described in the first aspect. According to an embodiment of this application, the friction material includes: preparing the aramid fiber, wherein the method for preparing the aramid fiber includes: placing the aramid fiber body in a nitrile rubber latex, mixing, and then drying the resulting mixture to obtain the aramid fiber.

[0123] According to embodiments of this application, the concentration of the nitrile rubber latex is 5wt% to 15wt%, for example, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, or 15wt%, preferably 8wt% to 12wt%. This helps to obtain a coating layer of suitable thickness, improving the overall damping performance and energy absorption capacity of the friction material. Under various temperature conditions, especially low temperatures, this not only helps to reduce noise generated during braking but also maintains the stability of the brake pad's hardness and coefficient of friction, thereby providing a smoother and more reliable braking effect and extending the service life of the brake pads.

[0124] In some embodiments, the aramid fiber body is placed in the nitrile rubber latex for 1 to 2 hours, for example, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, or 2 hours, preferably 1.3 to 1.7 hours. This helps to obtain a butyl rubber layer of suitable thickness, improving the overall damping performance and energy absorption capacity of the material. Under various temperature conditions, especially low temperatures, this not only helps to reduce noise generated during braking but also maintains the stability of the brake pad's hardness and coefficient of friction, thereby providing a smoother and more reliable braking effect and extending the service life of the brake pads.

[0125] In some embodiments, the drying process is carried out at a temperature of 50°C to 80°C, for example, 50°C, 60°C, 70°C, or 80°C, for a time of 40 min to 90 min, for example, 40 min, 50 min, 60 min, 70 min, 80 min, or 90 min. This allows the emulsion to dry quickly while preventing material denaturation.

[0126] In some embodiments, the nitrile rubber latex further comprises an organic solvent, the organic solvent being at least one of ethyl acetate and butyl acetate.

[0127] According to embodiments of this application, the method further includes: stirring at least one of the first adhesive, friction modifier, and pH adjuster with the first fiber to obtain the friction material; the stirring speed is 600–1000 r / min (e.g., 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min), and / or the stirring time is 10–30 min (e.g., 10 min, 15 min, 20 min, 25 min, 30 min). This facilitates rapid and uniform mixing of the components.

[0128] A third aspect of this application discloses a brake pad. According to an embodiment of this application, see [link to embodiment]. Figure 1 The brake pad includes: a substrate 100; and a friction layer 200 disposed on at least a portion of the surface of the substrate 100, the friction layer 200 comprising the friction material described in the first aspect. As previously mentioned, the friction material of this application has high damping performance, maintaining high vibration reduction and noise reduction effects under various temperature conditions, especially low temperature conditions, and also has advantages such as strong structural stability, strong thermal stability, corrosion resistance, wear resistance, impact resistance, and long service life.

[0129] According to embodiments of this application, the porosity of the friction layer 200 is 10% to 25%, for example, it can be 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, or 25%. When the porosity of the friction layer meets the above conditions, the heat generated during friction is easily dissipated, reducing the likelihood of thermal fade, resulting in good braking performance, structural stability, low wear rate, and minimal noise.

[0130] According to an embodiment of this application, at 25°C, the Rockwell hardness of the friction layer 200 is 60-75, for example, 60, 65, 70, or 75. A friction layer meeting these hardness requirements exhibits superior frictional performance and generates less noise.

[0131] According to an embodiment of this application, at -20°C, the Rockwell hardness of the friction layer 200 is 65 to 90, for example, 65, 70, 75, 80, 85, or 90. Therefore, a friction layer satisfying the above hardness has better frictional performance and generates less noise.

[0132] According to an embodiment of this application, the thickness of the friction layer 200 is 5cm to 9cm, for example, 5cm, 5.5cm, 6cm, 6.5cm, 7cm, 7.5cm, 8cm, 8.5cm, or 9cm. Therefore, a friction layer meeting the above thickness has better friction performance and generates less noise.

[0133] According to an embodiment of this application, the brake pad further includes: an adhesive layer 300, the adhesive layer 300 being disposed between the substrate 100 and the friction layer 200;

[0134] The adhesive layer includes an adhesive material comprising a second adhesive, a second fiber, and a filler. The adhesive layer serves to bond the friction layer to the substrate, preventing the friction layer from detaching from the substrate. The second fiber, acting as a reinforcing material, possesses high tensile strength, effectively improving the mechanical strength of the adhesive material and enhancing its impact resistance and crack resistance. The second adhesive binds the components together, stabilizing the structure of the adhesive material. The filler improves the adhesiveness, mechanical strength, and wear resistance of the adhesive material.

[0135] According to embodiments of this application, the second adhesive comprises at least one of phenolic resin and nitrile rubber. Phenolic resin readily bonds to other components in the bonding material, providing stable adhesion. Furthermore, phenolic resin exhibits good thermal stability, wear resistance, and corrosion resistance, extending the service life of the friction material and maintaining its performance under harsh environmental conditions. Nitrile rubber acts as a damping material, reducing noise. Additionally, nitrile rubber possesses excellent elasticity and oil resistance, enhancing the frictional performance and wear resistance of the friction material.

[0136] According to embodiments of this application, the second fiber comprises at least one of aramid fiber, steel fiber, and mineral fiber. These fibers act as a skeleton in the bonding material, increasing its mechanical strength and impact resistance, thereby improving its structural stability and impact resistance. They also help absorb and dissipate energy, reducing noise and vibration. Furthermore, mineral fibers also increase the flexibility and tensile strength of the friction material.

[0137] According to embodiments of this application, the filler comprises at least one selected from barium sulfate, vermiculite, graphite, zinc oxide, and calcium fluoride. Barium sulfate increases the coefficient of friction, hardness, strength, and thermal stability. Vermiculite expands at high temperatures, contributing to heat insulation and noise reduction. Graphite reduces the coefficient of friction and improves thermal stability. Zinc oxide enhances the material's heat resistance and corrosion resistance. Calcium fluoride improves the material's hardness and chemical stability.

[0138] According to embodiments of this application, based on the total weight of the adhesive material, the adhesive material comprises: 10-28 parts of a second adhesive, 27-50 parts of a second fiber, and 34-68 parts of filler; or, 15-20 parts of a second adhesive, 30-40 parts of a second fiber, and 45-55 parts of filler. This further improves the adhesive properties of the adhesive material, enabling the friction material to adhere stably to the substrate. Furthermore, it further improves the thermal stability, chemical stability, and noise reduction performance of the adhesive material.

[0139] According to an embodiment of this application, the thickness of the adhesive layer 300 is 1 cm to 3 cm. This facilitates stable adhesion between the friction material and the substrate.

[0140] According to embodiments of this application, the acrylonitrile content of the nitrile rubber is not higher than 24% by mass, and exemplaryly not less than 20% by mass, for example, it can be 24% by mass, 23% by mass, 22% by mass, 21% by mass, or 20% by mass. Therefore, the nitrile rubber exhibits superior adhesion.

[0141] According to embodiments of this application, the graphite particle size is 500 μm to 900 μm. Exemplarily, the graphite particle size is 500 μm, 600 μm, 700 μm, 800 μm, or 900 μm. This helps to uniformly disperse the graphite in the material, thereby improving overall frictional stability and performance consistency; furthermore, it provides a stable coefficient of friction at high temperatures, ensuring that braking performance is not affected by temperature changes; further still, it can reduce wear during friction, extending the service life of brake pads; simultaneously, it helps to improve the thermal conductivity of the material, helping to disperse the heat generated by friction and preventing localized overheating.

[0142] According to embodiments of this application, the porosity of the adhesive layer 300 is 5% to 8%, for example, 5%, 6%, 7%, or 8%. Therefore, the bonding strength is suitable, and the mechanical properties, thermal stability, and durability are excellent.

[0143] According to embodiments of this application, the substrate includes an aluminum alloy plate or a steel plate.

[0144] According to an embodiment of this application, the brake pad further includes a noise-reducing plate 400, which is disposed on the side of the substrate 100 away from the adhesive layer 300. This further reduces noise generated during braking.

[0145] It should be noted that the characteristics and advantages described above for friction materials also apply to the preparation methods of friction materials and brake pads, and will not be repeated here.

[0146] A fourth aspect of this application discloses a method for preparing the brake pads described in the third aspect. According to embodiments of this application, see [link to embodiment]. Figure 2 The method includes: S100 molding process and S200 curing process. Each step will be described in detail below.

[0147] S100 molding process

[0148] In this step, the friction material and the substrate are molded to obtain a molded blank. This allows the friction material to be formed and pre-cured in the mold, improving the uniformity and consistency of the friction material structure.

[0149] According to an embodiment of this application, the method further includes: molding the friction material, the adhesive material, and the substrate to obtain the molded preform. This allows the friction material and adhesive material to be formed and pre-cured in a mold, improving the uniformity and consistency of the structure of the friction material and adhesive material.

[0150] According to an embodiment of this application, the molding temperature is 140°C to 170°C, for example, 140°C, 150°C, 160°C, or 170°C.

[0151] And / or, the pressure of the molding process is 20MPa to 50MPa, for example, 20MPa, 30MPa, 40MPa, or 50MPa;

[0152] And / or, the molding process takes 3 to 10 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes.

[0153] Therefore, using the above molding conditions helps to obtain friction and adhesive layers that meet the above porosity requirements.

[0154] S200 curing treatment

[0155] In this step, the molded preform is cured to form the friction layer on at least a portion of the surface of the substrate, resulting in the brake pad. In some embodiments, the molded preform is cured to sequentially form the adhesive layer and the friction layer on at least a portion of the surface of the substrate, resulting in the brake pad. This further enhances the structural stability, thermal stability, and chemical stability of the material.

[0156] According to an embodiment of this application, the curing process includes a first heat treatment and a second heat treatment, satisfying at least one of the following conditions:

[0157] The temperature of the first heat treatment is 155℃~170℃, for example, 155℃, 160℃, 165℃, 170℃;

[0158] The duration of the first heat treatment is 4 to 8 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours.

[0159] The temperature of the second heat treatment is 200℃~250℃, for example, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃;

[0160] The second heat treatment time is 3h to 5h, for example, 3h, 3.5h, 4h, 4.5h, 5h.

[0161] Therefore, using the above-mentioned gradient curing conditions is beneficial for the resin to cure more thoroughly.

[0162] According to an embodiment of this application, the method further includes: bonding a sound-absorbing sheet to the side of the cured substrate away from the adhesive layer.

[0163] This application discloses a brake disc in its fifth aspect. According to an embodiment of this application, the brake disc includes the brake pads described in the third aspect. Therefore, the brake disc of this application has superior braking performance and is suitable for various temperature environments, especially maintaining excellent performance in low-temperature environments.

[0164] A sixth aspect of this application discloses a vehicle. According to an embodiment of this application, the vehicle includes: the brake pads described in the third aspect and / or the brake disc described in the fourth aspect. Therefore, the vehicle of this application has excellent braking performance.

[0165] In some embodiments, the vehicle includes pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, electric trains, etc.

[0166] It should be noted that the features and advantages described above for brake pads also apply to the method for manufacturing brake pads, brake discs, and vehicles, and will not be repeated here.

[0167] The following will explain the solution of this application with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0168] Example 1

[0169] I. Rubber Coating Treatment of Aramid Fibers

[0170] Nitrile rubber was dissolved in ethyl acetate to obtain a 10 wt% ethyl acetate solution of nitrile rubber. Aramid fibers were then immersed in the ethyl acetate solution of nitrile rubber for 1.5 h and dynamically dried at 60 °C to obtain aramid fibers coated with nitrile rubber, the volume of which was 10 times that of the aramid fibers before treatment. Figure 3 The image shown is of aramid fibers coated with nitrile rubber. Figure 4 Electron micrograph of aramid fibers coated with nitrile rubber is shown.

[0171] II. Preparation of Friction Materials and Bonding Materials

[0172] 1. Preparation of friction materials

[0173] The raw materials for the friction material, by weight, include: 7 parts of nitrile rubber and boric acid-modified phenolic resin, 2 parts of medium nitrile rubber with an ACN content of 27%, 2 parts of coupling agent (KH560), 2 parts of aramid fiber coated with nitrile rubber, 6 parts of copper fiber, 10 parts of copper powder, 25 parts of steel fiber, 6 parts of iron powder, 6 parts of graphite, 6 parts of vermiculite, 4 parts of molybdenum disulfide, 3 parts of zinc oxide, 2 parts of calcium hydroxide, 3 parts of aluminum oxide, and a pH value of 6.5.

[0174] Preparation method of phenolic resin modified by nitrile rubber and boric acid: 5 parts nitrile rubber, 5 parts boric acid and 90 parts phenolic resin are placed in a mixer and mixed at 150°C for 2 hours. The mixture is then taken out, crushed and passed through a 200-mesh sieve to obtain phenolic resin modified by nitrile rubber and boric acid.

[0175] The raw materials for friction material are placed in a plow-harrow mixer, the main shaft rotates at 700 r / min, and the mixture is stirred for 30 min to obtain the friction material.

[0176] 2. Preparation of adhesive materials

[0177] The raw materials of the bonding material, by weight, include: 12 parts of phenolic resin modified with nitrile rubber and boric acid, 3 parts of aramid fiber coated with nitrile rubber, 5 parts of low nitrile rubber with an ACN content of 22%, 25 parts of barium sulfate, 8 parts of vermiculite, 25 parts of steel fiber, 3 parts of graphite, 5 parts of zinc oxide, 8 parts of calcium fluoride, and 8 parts of mineral fiber.

[0178] Place the raw materials into a plow-harrow mixer, with the main shaft rotating at 800 r / min; mix for 20 min to obtain a binder material.

[0179] III. Hot pressing and curing of friction materials

[0180] Friction material, adhesive material and steel backing are added to a mold and pressed into shape. The molding temperature is 160℃, the molding pressure is 50MPa, and the holding time is 5min, resulting in a molded blank with a friction material thickness of 7cm and an adhesive material thickness of 2cm.

[0181] The molded blank is heated at 160℃ and held for 5 hours; then the temperature is raised to 220℃ and held for 4 hours to obtain the brake pad.

[0182] Example 2

[0183] I. Rubber Coating Treatment of Aramid Fibers

[0184] Nitrile rubber was dissolved in ethyl acetate to obtain a 10 wt% ethyl acetate solution of nitrile rubber. Aramid fibers were then immersed in the ethyl acetate solution of nitrile rubber for 1.5 h and dynamically dried at 60 °C to obtain aramid fibers coated with nitrile rubber, the volume of which was 10 times that of the aramid fibers before treatment.

[0185] II. Preparation of Friction Materials and Bonding Materials

[0186] 1. Preparation of friction materials

[0187] The raw materials for the friction material, by weight, include: 9 parts of nitrile rubber and boric acid-modified phenolic resin, 3 parts of medium nitrile rubber with an ACN content of 27%, 2 parts of coupling agent (KH560), 2 parts of aramid fiber coated with nitrile rubber, 8 parts of copper fiber, 12 parts of copper powder, 25 parts of steel fiber, 8 parts of iron powder, 8 parts of graphite, 7 parts of vermiculite, 5 parts of molybdenum disulfide, 5 parts of zinc oxide, 3 parts of calcium hydroxide, 3 parts of aluminum oxide, and a pH value of 6.5.

[0188] Preparation method of phenolic resin modified by nitrile rubber and boric acid: same as in Example 1.

[0189] The raw materials are placed in a plow and harrow mixer, the main shaft rotates at 700 r / min, and the mixture is stirred for 30 minutes to obtain friction material.

[0190] 2. Preparation of adhesive materials

[0191] The raw materials of the bonding material, by weight, include: 12 parts of phenolic resin modified with nitrile rubber and boric acid, 3 parts of aramid fiber coated with nitrile rubber, 5 parts of low nitrile rubber with an ACN content of less than 24%, 25 parts of barium sulfate, 8 parts of vermiculite, 25 parts of steel fiber, 3 parts of graphite, 5 parts of zinc oxide, 8 parts of calcium fluoride, and 8 parts of mineral fiber.

[0192] Place the raw materials into a plow-harrow mixer, with the main shaft rotating at 800 r / min; mix for 20 min to obtain a binder material.

[0193] III. Hot pressing and curing of friction materials

[0194] Friction material, adhesive material and steel backing are added to a mold and pressed into shape. The molding temperature is 160℃, the molding pressure is 35MPa, and the holding time is 5min, resulting in a molded blank with a friction material thickness of 7cm and an adhesive material thickness of 2cm.

[0195] The molded blank is heated at 160℃ and held for 5 hours; then the temperature is raised to 220℃ and held for 4 hours to obtain the brake pad.

[0196] Example 3

[0197] I. Rubber Coating Treatment of Aramid Fibers

[0198] Nitrile rubber was dissolved in ethyl acetate to obtain a 10 wt% ethyl acetate solution of nitrile rubber. Aramid fibers were then immersed in the ethyl acetate solution of nitrile rubber for 1.5 h and dynamically dried at 60 °C to obtain aramid fibers coated with nitrile rubber, the volume of which was 10 times that of the aramid fibers before treatment.

[0199] II. Preparation of Friction Materials and Bonding Materials

[0200] 1. Preparation of friction materials

[0201] The raw materials for the friction material, by weight, include: 11 parts of phenolic resin modified with nitrile rubber and boric acid, 4 parts of medium nitrile rubber with an ACN content of 27%, 2 parts of coupling agent (KH560), 2 parts of aramid fiber coated with nitrile rubber, 10 parts of copper fiber, 14 parts of copper powder, 25 parts of steel fiber, 8 parts of iron powder, 8 parts of graphite, 7 parts of vermiculite, 7 parts of molybdenum disulfide, 7 parts of zinc oxide, 4 parts of calcium hydroxide, 3 parts of aluminum oxide, and a pH value of 6.5.

[0202] Preparation method of phenolic resin modified by nitrile rubber and boric acid: Same as in Example 1. Place the raw materials in a plow-harrow mixer, rotate the main shaft at 700 r / min, and stir for 30 min to obtain friction material.

[0203] 2. Preparation of adhesive materials

[0204] The raw materials of the bonding material, by weight, include: 12 parts of phenolic resin modified with nitrile rubber and boric acid, 3 parts of aramid fiber coated with nitrile rubber, 5 parts of low nitrile rubber with an ACN content of less than 24%, 25 parts of barium sulfate, 8 parts of vermiculite, 25 parts of steel fiber, 3 parts of graphite, 5 parts of zinc oxide, 8 parts of calcium fluoride, and 8 parts of mineral fiber.

[0205] Place the raw materials into a plow-harrow mixer, with the main shaft rotating at 800 r / min; mix for 20 min to obtain a binder material.

[0206] III. Hot pressing and curing of friction materials

[0207] Friction material, adhesive material and steel backing are added to a mold and pressed into shape. The molding temperature is 160℃, the molding pressure is 20MPa, and the holding time is 5min, resulting in a molded blank with a friction material thickness of 7cm and an adhesive material thickness of 2cm.

[0208] The molded blank is heated at 160℃ and held for 5 hours; then heated to 220℃ and held for 4 hours to obtain the brake pad.

[0209] Example 4

[0210] I. Rubber Coating Treatment of Aramid Fibers

[0211] Nitrile rubber was dissolved in ethyl acetate to obtain a 5 wt% ethyl acetate solution of nitrile rubber. Aramid fibers were then immersed in the ethyl acetate solution of nitrile rubber for 1.5 h and dynamically dried at 60 °C to obtain aramid fibers coated with nitrile rubber, the volume of which was 10 times that of the aramid fibers before treatment.

[0212] II. Preparation of Friction Materials and Bonding Materials

[0213] Same as Example 2.

[0214] III. Hot pressing and curing of friction materials

[0215] Same as Example 2.

[0216] Example 5

[0217] I. Rubber Coating Treatment of Aramid Fibers

[0218] Nitrile rubber was dissolved in ethyl acetate to obtain a 15 wt% ethyl acetate solution of nitrile rubber. Aramid fibers were then immersed in the ethyl acetate solution of nitrile rubber for 1.5 h and dynamically dried at 60 °C to obtain aramid fibers coated with nitrile rubber, the volume of which was 10 times that of the aramid fibers before treatment.

[0219] II. Preparation of Friction Materials and Bonding Materials

[0220] Same as Example 2.

[0221] III. Hot pressing and curing of friction materials

[0222] Same as Example 2.

[0223] Example 6

[0224] I. Rubber Coating Treatment of Aramid Fibers

[0225] Nitrile rubber was dissolved in ethyl acetate to obtain a 10 wt% ethyl acetate solution of nitrile rubber. Aramid fibers were then immersed in the ethyl acetate solution of nitrile rubber for 1 hour and dynamically dried at 60°C to obtain aramid fibers coated with nitrile rubber, the volume of which was 10 times that of the aramid fibers before treatment.

[0226] II. Preparation of Friction Materials and Bonding Materials

[0227] Same as Example 2.

[0228] III. Hot pressing and curing of friction materials

[0229] Same as Example 2.

[0230] Example 7

[0231] I. Rubber Coating Treatment of Aramid Fibers

[0232] Nitrile rubber was dissolved in ethyl acetate to obtain a 10 wt% ethyl acetate solution of nitrile rubber. Aramid fibers were then immersed in the ethyl acetate solution of nitrile rubber for 2 hours and dynamically dried at 60°C to obtain aramid fibers coated with nitrile rubber, the volume of which was 10 times that of the aramid fibers before treatment.

[0233] II. Preparation of Friction Materials and Bonding Materials

[0234] Same as Example 2.

[0235] III. Hot pressing and curing of friction materials

[0236] Same as Example 2.

[0237] Example 8

[0238] I. Rubber Coating Treatment of Aramid Fibers

[0239] Same as Example 2.

[0240] II. Preparation of Friction Materials and Bonding Materials

[0241] 1. Preparation of friction materials

[0242] The raw materials for friction materials, by weight, include: 9 parts phenolic resin, 3 parts medium-density nitrile rubber with an ACN content of 25%-30%, 2 parts coupling agent (KH560), 2 parts aramid fiber coated with nitrile rubber, 8 parts copper fiber, 12 parts copper powder, 25 parts steel fiber, 8 parts iron powder, 8 parts graphite, 7 parts vermiculite, 5 parts molybdenum disulfide, 5 parts zinc oxide, 3 parts calcium hydroxide, and 3 parts aluminum oxide.

[0243] The raw materials are placed in a plow and harrow mixer, the main shaft rotates at 700 r / min, and the mixture is stirred for 30 minutes to obtain friction material.

[0244] 2. Preparation of adhesive materials

[0245] Same as Example 2.

[0246] III. Hot pressing and curing of friction materials

[0247] Same as Example 2.

[0248] Example 9

[0249] I. Rubber Coating Treatment of Aramid Fibers

[0250] Same as Example 2.

[0251] II. Preparation of Friction Materials and Bonding Materials

[0252] 1. Preparation of friction materials

[0253] The raw materials for friction materials, by weight, include: 9 parts of phenolic resin modified with nitrile rubber, 3 parts of medium nitrile rubber with an ACN content of 25%-30%, 2 parts of coupling agent (KH560), 2 parts of aramid fiber coated with nitrile rubber, 8 parts of copper fiber, 12 parts of copper powder, 25 parts of steel fiber, 8 parts of iron powder, 8 parts of graphite, 7 parts of vermiculite, 5 parts of molybdenum disulfide, 5 parts of zinc oxide, 3 parts of calcium hydroxide, and 3 parts of aluminum oxide.

[0254] Preparation method of nitrile rubber modified phenolic resin: 10 parts of nitrile rubber and 90 parts of phenolic resin are placed in a mixer and mixed at 150°C for 2 hours. The mixture is then taken out, crushed, and passed through a 200-mesh sieve to obtain nitrile rubber modified phenolic resin.

[0255] The raw materials are placed in a plow and harrow mixer, the main shaft rotates at 700 r / min, and the mixture is stirred for 30 minutes to obtain friction material.

[0256] 2. Preparation of adhesive materials

[0257] Same as Example 2.

[0258] III. Hot pressing and curing of friction materials

[0259] Same as Example 2.

[0260] Example 10

[0261] I. Rubber Coating Treatment of Aramid Fibers

[0262] Same as Example 2.

[0263] II. Preparation of Friction Materials and Bonding Materials

[0264] 1. Preparation of friction materials

[0265] The raw materials for friction materials, by weight, include: 9 parts boric acid-modified phenolic resin, 3 parts medium-density nitrile rubber with an ACN content of 25%-30%, 2 parts coupling agent (KH560), 2 parts aramid fiber coated with nitrile rubber, 8 parts copper fiber, 12 parts copper powder, 25 parts steel fiber, 8 parts iron powder, 8 parts graphite, 7 parts vermiculite, 5 parts molybdenum disulfide, 5 parts zinc oxide, 3 parts calcium hydroxide, and 3 parts aluminum oxide.

[0266] Preparation method of boric acid modified phenolic resin: 10 parts boric acid and 90 parts phenolic resin are placed in a mixer and mixed at 150°C for 2 hours to obtain boric acid modified phenolic resin.

[0267] The raw materials are placed in a plow and harrow mixer, the main shaft rotates at 700 r / min, and the mixture is stirred for 30 minutes to obtain friction material.

[0268] 2. Preparation of adhesive materials

[0269] Same as Example 2.

[0270] III. Hot pressing and curing of friction materials

[0271] Same as Example 2.

[0272] Example 11

[0273] The difference from Example 2 is that the aramid fiber coated with nitrile rubber is 6 parts.

[0274] Example 12

[0275] The difference from Example 2 is that the amount of phenolic resin modified by nitrile rubber and boric acid is 15 parts.

[0276] Example 13

[0277] The difference from Example 2 is that the volume of the aramid fiber coated with nitrile rubber is 6 times that of the aramid fiber before treatment.

[0278] Example 14

[0279] The difference from Example 2 is that the volume of the aramid fiber coated with nitrile rubber is 14 times that of the aramid fiber before treatment.

[0280] Comparative Example 1

[0281] The difference from Example 2 is that the aramid fibers coated with nitrile rubber are replaced with aramid fibers.

[0282] Test case

[0283] 1. The thickness of the nitrile rubber layer in the aramid fibers coated with nitrile rubber prepared in Examples 1 and 4-7 was measured using a scanning electron microscope.

[0284] Table 1. Thickness of the nitrile rubber layer in aramid fibers coated with nitrile rubber.

[0285]

[0286] 2. The friction layer and adhesive layer of the brake pads prepared in Examples 1-15 and Comparative Example 1 were tested respectively. The specific steps are as follows:

[0287] Porosity: Measured using the vacuum water absorption method.

[0288] Rockwell hardness: Measured using a Rockwell hardness tester according to national standard GB / T 5766-2023.

[0289] The physical properties of the friction layer are shown in Table 2. The physical properties of the adhesive layer are as follows: the density of the adhesive layer is 2.75 g / cm³. 3 The bonding layer has a porosity of 6%, a Rockwell hardness of 60 at room temperature (25℃), a Rockwell hardness of 63 at low temperature (-20℃), a thickness of 2cm, and a shear strength of 10.5MPa. Table 2 shows the physical properties of the friction layer and bonding layer of the brake pad.

[0290]

[0291] 3. The brake pads prepared in Examples 1-14 and Comparative Example 1 were subjected to extreme cold noise bench tests according to SAE J2521 2006 standard. The results are shown in Table 3.

[0292] Table 3 Noise Test

[0293]

[0294]

[0295]

[0296] As shown in Tables 2 and 3, the friction layers prepared in Examples 1-14 exhibited minimal hardness changes at room temperature and low temperature, and generated fewer noises in room temperature, high temperature, and low temperature environments. In Comparative Example 1, because the aramid fibers lacked an nitrile rubber coating, the friction layer showed a significant increase in hardness at low temperatures, and generated more noises in room temperature, high temperature, and low temperature environments.

[0297] As can be seen from Examples 2, 4, and 5, the thickness of the nitrile rubber layer increases with the increase of the nitrile rubber emulsion concentration. As can be seen from Examples 2, 6, and 7, the thickness of the nitrile rubber layer increases with the increase of the aramid fiber soaking time. Compared with Examples 2 and 4-7, the brake pad of Example 2 has the best noise test results in normal temperature, high temperature, and low temperature environments.

[0298] As can be seen from Examples 2 and 8-10, modification of phenolic resin with nitrile rubber can improve its thermal properties and damping performance, thus better fulfilling its noise reduction and vibration damping functions. Modification of phenolic resin with boric acid is beneficial for improving the heat resistance and damping performance of friction materials, reducing the frequency of noise generation. The phenolic resin obtained by composite modification with butyl rubber and boric acid exhibits even better overall performance.

[0299] As can be seen from Examples 2, 11, and 12, the excessive addition of nitrile rubber and boric acid-modified phenolic resin results in a higher overall binder content, which in turn leads to more frequent brake pad noise. Similarly, the high addition of aramid fiber coated with nitrile rubber results in a higher overall fiber content, also contributing to more frequent brake pad noise. When the friction material comprises 1–4 parts aramid fiber and 9–20 parts binder, the overall performance of the brake pad is better.

[0300] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A friction material, characterized by, Comprising: a first fiber, the first fiber comprising: an aramid fiber, the aramid fiber comprising: an aramid fiber body; 2. The friction material of claim 1, wherein a coating layer covering at least a part of a surface of the aramid fiber body, the coating layer comprising nitrile rubber. The thickness of the coating layer is 1 μm to 7 μm; 3. The friction material of claim 1, wherein and / or, the volume of the aramid fiber is 8 to 12 times the volume of the aramid fiber body.

4. The friction material of claim 1 wherein, The thickness of the coating layer is 3 μm to 5 μm.

5. The friction material of claim 4 wherein, The first fiber further comprises at least one of a copper fiber and a steel fiber. The first fiber further comprises a copper fiber and a steel fiber, the first fiber comprising, based on the total weight of the friction material: 1 to 4 parts of the aramid fiber; 5 to 10 parts of the copper fiber; 6. The friction material of any one of claims 1-5, wherein 20 to 30 parts of the steel fiber.

7. The friction material of claim 6 wherein, Further comprising a first binder, the first binder comprising a phenol resin.

8. The friction material of claim 6 wherein, The phenol resin is selected from a group consisting of a nitrile rubber-modified and / or a boric acid-modified phenol resin.

9. The friction material of claim 6 wherein, The friction material comprises, based on the total weight of the friction material: 1 to 4 parts of the aramid fiber and 9 to 20 parts of the first binder; or, 1 to 4 parts of the first fiber and 11 to 17 parts of the first binder. The first binder further comprises at least one of a butyl rubber and a coupling agent; 10. The friction material of claim 9, wherein The coupling agent comprises a silane coupling agent and / or a titanate coupling agent. The first binder comprises, based on the total weight of the friction material: 6 to 12 parts of the phenol resin; 2 to 5 parts of the nitrile rubber; 11. The friction material of any one of claims 1-5, wherein 1 to 3 parts of the coupling agent.

12. The friction material of claim 11, wherein, Further comprising a friction modifier, the friction modifier comprising at least one of iron powder, copper powder, graphite, vermiculite, molybdenum disulfide, zinc oxide, and aluminum oxide. The friction material comprises, based on the total weight of the friction material: 1 to 4 parts of the aramid fiber and 32 to 66 parts of the friction modifier; or, 1 to 4 parts of the aramid fiber and 38 to 51 parts of the friction modifier; 13. The friction material of any one of claims 1-5, wherein and / or, the friction modifier comprises iron powder, copper powder, graphite, vermiculite, molybdenum disulfide, zinc oxide, and aluminum oxide, the friction modifier comprising, based on the total weight of the friction material: 10 to 15 parts of copper powder, 5 to 10 parts of iron powder, 5 to 10 parts of graphite, 5 to 10 parts of vermiculite, 3 to 8 parts of molybdenum disulfide, 2 to 8 parts of zinc oxide, and 2 to 5 parts of aluminum oxide.

14. The friction material of claim 13, wherein The friction material has a pH value of 6.0 to 7.0, the friction material further comprising a pH adjuster, the pH adjuster comprising calcium hydroxide.

15. The friction material of claim 1 wherein, The friction material comprises, based on the total weight of the friction material: 1 to 4 parts of the aramid fiber and 2 to 4 parts of the pH adjuster; or, 1 to 4 parts of the aramid fiber and 2 to 4 parts of the pH adjuster. The friction material comprises, based on the total weight of the friction material: 26 to 44 parts of a first fiber, the first fiber comprising: 1 to 4 parts of the aramid fiber, 5 to 10 parts of the copper fiber, and 20 to 30 parts of the steel fiber; 9 to 20 parts of a first binder, the first binder comprising: 6 to 12 parts of the phenol resin, 2 to 5 parts of the nitrile rubber, and 1 to 3 parts of the coupling agent; 32-66 parts of a friction modifier, the friction modifier comprising: 10-15 parts of copper powder, 5-10 parts of iron powder, 5-10 parts of graphite, 5-10 parts of vermiculite, 3-8 parts of molybdenum disulfide, 2-8 parts of zinc oxide and 2-5 parts of aluminum oxide; 2-4 parts of a pH modifier, the pH modifier comprising calcium hydroxide.

16. A method of producing the friction material according to any one of claims 1 to 15, characterized by, Comprising: preparing the aramid fiber, the method for preparing the aramid fiber comprising: placing the aramid fiber body into a nitrile rubber emulsion, mixing, and then drying the obtained mixture to obtain the aramid fiber.

17. The method of claim 16, wherein, The concentration of the nitrile rubber emulsion is 5wt%-15wt%; and / or, the aramid fiber body is placed in the nitrile rubber emulsion for 1h-2h; and / or, the drying treatment is carried out at a temperature of 50°C-80°C for 40min-90min.

18. The method of claim 16, wherein, The concentration of the nitrile rubber emulsion is 8wt%-12wt%; and / or, the aramid fiber body is placed in the nitrile rubber emulsion for 1.3h-1.7h.

19. The method of claim 16, wherein, Further comprising: stirring at least one of the first binder, the friction modifier and the pH modifier with the first fiber to obtain the friction material; The stirring speed is 600-1000r / min, and / or, the stirring time is 10-30min.

20. A brake pad, characterized by Comprising: a substrate; a friction layer, the friction layer being arranged on at least part of the surface of the substrate, the friction layer comprising the friction material according to any one of claims 1-15.

21. The brake pad of claim 20, wherein, The porosity of the friction layer is 10%-25%; and / or, the Rockwell hardness of the friction layer is 60-75 at 25°C; and / or, the Rockwell hardness of the friction layer is 65-90 at -20°C; and / or, the thickness of the friction layer is 5cm-9cm.

22. The brake pad of claim 20, wherein Further comprising: a bonding layer, the bonding layer being arranged between the substrate and the friction layer; The bonding layer comprises a bonding material, the bonding material comprising: a second binder, a second fiber and a filler.

23. The brake pad of claim 22, wherein, The second binder comprises at least one of phenolic resin and nitrile rubber; and / or, the second fiber comprises at least one of aramid fiber, steel fiber and mineral fiber; and / or, the filler comprises at least one of barium sulfate, vermiculite, graphite, zinc oxide and calcium fluoride; and / or, the bonding material comprises: 10-28 parts of the second binder, 27-50 parts of the second fiber and 34-68 parts of the filler; or, 15-20 parts of the second binder, 30-40 parts of the second fiber and 45-55 parts of the filler; and / or, the thickness of the bonding layer is 1cm-3cm.

24. A method of making the brake pad of any one of claims 20 to 23, characterized by, Comprising: molding the friction material and the substrate to obtain a molded body; solidifying the molded body to form the friction layer on at least part of the surface of the substrate to obtain the brake pad.

25. The method of claim 24, wherein, Further comprising: molding the friction material, the bonding material and the substrate to obtain the molded body; The mold pressing blank is subjected to a solidification treatment to sequentially form the bonding layer and the friction layer on at least part of the surface of the base material, thereby obtaining the brake pad.

26. The method of claim 24, wherein, The temperature of the mold pressing treatment is 140-170°C; And / or, the pressure of the mold pressing treatment is 20-50 MPa; And / or, the time of the mold pressing treatment is 3-10 min; And / or, the solidification treatment comprises a first heating treatment and a second heating treatment, at least one of the following conditions being satisfied: The temperature of the first heating treatment is 155-170°C; The time of the first heating treatment is 4-8 h; The temperature of the second heating treatment is 200-250°C; The time of the second heating treatment is 3-5 h.

27. A brake disc characterised in that Comprising: The brake pad of any one of claims 20-23.

28. A vehicle characterized by Comprising: The brake pad of any one of claims 20-23 and / or the brake disc of claim 27.

Images