Brake pad friction material and method of making and using same

Abstract

The application relates to the technical field of braking material, and particularly discloses a kind of friction material for brake pad and a preparation method and application thereof.The friction material for brake pad comprises the following raw material components in mass fraction: nitrile rubber / cashew nut shell oil modified phenolic resin, styrene-butadiene rubber, basalt short fiber, wear-resistant aggregate and rust-preventive corrosion inhibitor;wherein the wear-resistant aggregate comprises wollastonite, calcined red mud powder, metakaolin and molybdenum disulfide;the rust-preventive corrosion inhibitor comprises magnesium-aluminum hydrotalcite, calcium hydroxide and octyl triethoxysilane modified nano-silicon dioxide.The friction material for brake pad has wear resistance, high-temperature friction stability and rust-preventive bonding capacity, effectively making up for the deficiencies of the prior art.

Description

Technical Field

[0001] This invention relates to the field of braking materials technology, and in particular to a friction material for brake pads, its preparation method, and its application. Background Technology

[0002] Automotive brake pads typically use resin-based friction materials, which are made with phenolic resin or modified phenolic resin as the binder, combined with reinforcing fibers, friction modifiers, lubricants, and inorganic fillers. These materials are produced through mixing, hot pressing, and curing. The process is mature and the materials have good formability, making them widely used in disc brakes. However, existing resin-based brake pads have the following three problems: First, under high load, long downhill, or continuous braking conditions, the temperature at the friction interface rises rapidly. The resin phase is prone to thermal decomposition, uneven carbonization, and decreased bonding strength, leading to a loose surface, localized peeling, and accelerated wear of the friction layer. This, in turn, causes a decrease in the high-temperature friction coefficient and reduced braking stability. Second, to improve wear resistance, existing technologies typically use ceramic abrasives, hard mineral fillers, or inorganic reinforcing skeletons. However, if the bonding between the hard components and the resin matrix is ​​insufficient, or if a stable third-party transfer film is lacking in the friction layer, surface brittle shedding, friction fluctuations, and abnormal wear can still easily occur during repeated braking. Third, automotive disc brakes are exposed to rain, car washes, wading, humid air, and salt spray environments for extended periods. The pores on the friction pad surface easily absorb moisture, and the iron at the brake disc contact points is easily oxidized to form iron oxide, which seeps into the pores on the friction pad surface, resulting in rust adhesion. In severe cases, this can lead to the friction pads sticking to the brake disc, difficulty in starting separation, or even brake jamming.

[0003] To address the aforementioned issues, existing technologies have improved resin-based brake pads through filler reinforcement, nano-modification, rust-preventive fillers, and high-temperature surface treatment. However, most solutions still focus on optimizing a single performance aspect, making it difficult to simultaneously achieve wear resistance, high-temperature friction stability, and rust-preventive adhesion.

[0004] Therefore, developing a brake pad material that combines a wear-resistant skeleton, a high-temperature stable friction interface, and rust-proof bonding functions in a resin-based system remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of this, the present invention provides a friction material for brake pads, its preparation method, and its application. The friction material for brake pads of the present invention utilizes a bonding and toughening system composed of nitrile rubber / cashew shell oil-modified phenolic resin and styrene-butadiene rubber, with basalt short fibers and wear-resistant aggregate forming a reinforcing support skeleton, supplemented by a rust-inhibiting and corrosion-inhibiting system, to give the resulting resin-based brake pad friction material wear resistance, high-temperature friction stability, and rust-proof bonding ability.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The first aspect of the present invention provides a friction material for brake pads, comprising the following raw material components in parts by weight: 20-30 parts of nitrile rubber / cashew shell oil modified phenolic resin, 10-20 parts of styrene-butadiene rubber, 20-40 parts of basalt short fiber, 10-15 parts of wear-resistant aggregate, and 3-5 parts of rust inhibitor and corrosion inhibitor. The wear-resistant aggregate includes wollastonite, calcined red mud powder, metakaolin, and molybdenum disulfide; the rust inhibitor includes magnesium aluminum hydrotalcite, calcium hydroxide, and octyltriethoxysilane-modified nano-silica.

[0007] Compared to existing technologies, the nitrile rubber / cashew shell oil modified phenolic resin and styrene-butadiene rubber in this invention constitute the bonding and toughening system in the friction material structure for brake pads. The nitrile rubber / cashew shell oil modified phenolic resin not only provides basic bonding strength and a heat-resistant skeleton but also exhibits excellent flexibility and impact resistance. The styrene-butadiene rubber further mitigates thermal and mechanical stresses, ensuring the friction material maintains good integrity and crack resistance under high temperature and alternating load conditions. Basalt short fibers and wear-resistant aggregates together form a reinforcing support skeleton, improving the tear resistance and structural stability of the friction material for brake pads through fiber bridging. The latter enhances the microscopic support and shear resistance of the friction material, improving the hardness of the friction layer and its high-temperature wear resistance. Both work synergistically to improve the wear resistance and high-temperature friction stability of the brake pads under continuous braking conditions. The addition of rust inhibitors and corrosion inhibitors reduces water vapor penetration and rust product formation, contributing to improved rust-resistant bonding capabilities of the friction material for brake pads. This invention utilizes the synergistic effect of each raw material component to endow the friction material for brake pads with good wear resistance, high-temperature friction stability and excellent anti-rust and bonding performance, thus overcoming the problem that existing resin-based brake pad materials cannot simultaneously achieve wear resistance, high-temperature friction stability and anti-rust and bonding ability.

[0008] Preferably, the wear-resistant aggregate comprises the following raw material components in the following mass percentages: 15%-20% wollastonite, 20%-30% calcined red mud powder, 50%-60% metakaolin, and 5-10% molybdenum disulfide.

[0009] More preferably, the wollastonite has a particle size of 10-50 μm and an aspect ratio of 5-15.

[0010] The needle-like or short columnar structure of wollastonite helps to build a more stable microscopic support network in the resin matrix, improves the density and shear resistance of the friction layer, and reduces excessive particle shedding during friction.

[0011] More preferably, the preparation method of the calcined red mud powder includes the following steps: ball milling the dried red mud to obtain pretreated red mud powder; heating the pretreated red mud powder to 380-500℃ for calcination to obtain the calcined red mud powder.

[0012] More preferably, the pretreated red mud powder has a particle size of 500-800 nm.

[0013] More preferably, the calcination time is 2-4 hours.

[0014] After calcination, red mud powder can improve the hardness and wear resistance of the friction layer, alleviate the problem of insufficient support caused by the softening of the resin phase at high temperature, and thus improve the friction stability of brake pads under high temperature continuous braking conditions and extend their service life.

[0015] More preferably, the particle size of the metakaolin is 50-100 μm.

[0016] When metakaolin is used in combination with calcined red mud powder, it can fill the pores between red mud particles and resin phase, thereby increasing the overall density of the friction layer. On the other hand, it can enhance the continuity and uniformity of the skeleton under high-temperature conditions, and reduce local stress concentration and pore expansion.

[0017] More preferably, the purity of the molybdenum disulfide is ≥98wt%.

[0018] Molybdenum disulfide can reduce local shear stress at the friction interface, thereby reducing dry friction, adhesive wear, and abnormal wear on the friction layer surface under high-temperature conditions. Simultaneously, the physical isolation effect of molybdenum disulfide on the friction interface can also reduce the direct bonding of rust products to the friction layer under humid conditions, thus playing an auxiliary role in rust prevention and adhesion.

[0019] Preferably, the rust inhibitor comprises magnesium aluminum hydrotalcite, calcium hydroxide, and octyltriethoxysilane-modified nano-silica in a mass ratio of 3:2:1 to 4:3:1.

[0020] More preferably, the magnesium aluminum hydrotalcite is a carbonate-type magnesium aluminum hydrotalcite with a Mg / Al molar ratio of 2:1-4:1.

[0021] The layered structure of magnesium aluminum hydrotalcite is beneficial for adsorbing moisture and some corrosive ions, and provides a relatively stable alkaline environment at the interface, thereby reducing the formation and diffusion of corrosion products. Nano-silica itself can improve the density, mechanical strength and wear resistance of the friction layer, and help slow down high-temperature thermal decay; octyltriethoxysilane reduces the surface energy and agglomeration of nano-silica by forming an organic hydrophobic chain layer on the surface of nano-silica, making it more uniformly dispersed in the resin matrix, while significantly reducing the adsorption and penetration of water vapor on the surface of the friction material.

[0022] Preferably, the preparation method of the nitrile rubber / cashew shell oil modified phenolic resin includes the following steps: mixing phenolic resin and cashew shell oil evenly, stirring at 65-80℃ for 20-30 min to obtain a premix; adding nitrile rubber to the premix, kneading at 110-130℃ for 1-2 h, and discharging to obtain the nitrile rubber / cashew shell oil modified phenolic resin.

[0023] More preferably, the mass ratio of the phenolic resin powder, cashew nut shell oil, and nitrile rubber is 100:6:10-100:6:15.

[0024] More preferably, the softening point of the phenolic resin powder is 90-105℃.

[0025] More preferably, the cashew nut shell oil has an acid value ≤10 mgKOH / g and a viscosity of 50-200 mPa·s at 30°C.

[0026] More preferably, the Mooney viscosity ML(1+4) of the nitrile rubber at 100°C is 40-70.

[0027] Preferably, the preparation method of the octyltriethoxysilane modified nano-silica includes the following steps: S1. Disperse nano-silica in anhydrous ethanol to obtain a silica dispersion; S2. Dissolve octyltriethoxysilane in an alcohol solution and adjust the pH to 4.8-5.2 to obtain octyltriethoxysilane hydrolysate; S3. The octyltriethoxysilane hydrolysate is slowly added to the silica dispersion and reacted at 65-70℃ for 6-8 hours. After solid-liquid separation and drying, the octyltriethoxysilane modified nano silica is obtained.

[0028] More preferably, in S1, the particle size of the nano-silica is 200-400 nm.

[0029] More preferably, in S1, the mass-to-volume ratio of the nano-silica to the anhydrous ethanol is 1g:3mL-1g:5mL.

[0030] More preferably, in S2, the mass-to-volume ratio of the octyltriethoxysilane to the alcohol solution is 1g:2mL-1g:3mL; wherein the alcohol solution is an ethanol solution with a mass fraction of 70%-80%.

[0031] More preferably, in S3, the mass ratio of the octyltriethoxysilane hydrolysate to the silica dispersion is 0.1:1-0.2:1.

[0032] A second aspect of the present invention provides a brake pad made of the aforementioned brake pad friction material.

[0033] A third aspect of the present invention provides a method for preparing the aforementioned friction material for brake pads, comprising the following steps: Step 1: Weigh each raw material component according to the design ratio, mix them evenly to obtain the mixture; Step 2: Heat the mixture to 150-165℃ and hot press it at 25-35MPa to obtain a hot-pressed body; Step 3: The hot-pressed molded body is heated to 180-210℃ for a second curing treatment, cooled, and processed into shape to obtain the brake pad precursor material; Step 4: Perform a short-term high-temperature surface ablation treatment on the brake pad precursor material at 520-580℃ to obtain the brake pad.

[0034] Preferably, in step three, the heat preservation time for the curing treatment is 4-6 hours.

[0035] Preferably, in step four, the short-time ablation treatment time for the high-temperature surface is 1-3 minutes.

[0036] The fourth aspect of the present invention provides the application of the brake pads in the field of automobile manufacturing.

[0037] In summary, this invention uses nitrile rubber / cashew shell oil modified phenolic resin, styrene-butadiene rubber, basalt short fibers, wear-resistant aggregates, and rust and corrosion inhibitors as the main raw material components to prepare a friction material for brake pads with high wear resistance, high-temperature friction stability, and rust-proof adhesion properties, thus overcoming the shortcomings of the prior art. Detailed Implementation

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The wollastonite used in the following examples and comparative examples has a particle size of 30 μm and an aspect ratio of 10.

[0040] The preparation method of the calcined red mud powder used in the following examples and comparative examples includes the following steps: ball milling the dried red mud to obtain pretreated red mud powder with a particle size of 600 nm; heating the pretreated red mud powder to 450°C and calcining it for 3 hours to obtain the calcined red mud powder.

[0041] The metakaolin used in the following examples and comparative examples has a particle size of 100 μm.

[0042] The purity of molybdenum disulfide used in the following examples and comparative examples is ≥98wt%.

[0043] The magnesium aluminum hydrotalcite used in the following examples and comparative examples is carbonate-type magnesium aluminum hydrotalcite with a Mg / Al molar ratio of 3:1.

[0044] The softening point of the phenolic resin powder used in the following examples and comparative examples is 90-105℃.

[0045] The cashew nut shell oil used in the following examples and comparative examples has an acid value of 5 mgKOH / g and a viscosity of 100 mPa·s at 30°C.

[0046] The Mooney viscosity ML(1+4) of the nitrile rubber used in the following examples and comparative examples is 60 at 100°C.

[0047] Example 1 This embodiment provides a friction material for brake pads and a brake pad prepared therefrom, comprising the following raw material components in parts by weight: 25 parts of nitrile rubber / cashew shell oil modified phenolic resin, 15 parts of styrene-butadiene rubber, 30 parts of basalt short fiber, 12 parts of wear-resistant aggregate, and 4 parts of rust inhibitor and corrosion inhibitor. The wear-resistant aggregate comprises the following raw material components by mass percentage: 18% wollastonite, 20% calcined red mud powder, 55% metakaolinite, and 7% molybdenum disulfide; the rust inhibitor comprises magnesium aluminum hydrotalcite, calcium hydroxide, and octyltriethoxysilane modified nano-silica in a mass ratio of 3:2:1.

[0048] The friction material for the brake pads includes the following steps: Step 1: Weigh each raw material component according to the design ratio, mix them evenly to obtain the mixture; Step 2: Heat the mixture to 160°C and hot press it at 28MPa to obtain a hot-pressed body; Step 3: The hot-pressed molded body is heated to 195°C for a second time and cured for 5 hours. After cooling, it is processed and shaped to obtain the brake pad precursor material. Step 4: Perform a short-term high-temperature surface ablation treatment on the brake pad precursor material at 550°C for 2 minutes to obtain the brake pad.

[0049] The preparation method of the nitrile rubber / cashew shell oil modified phenolic resin includes the following steps: 500g of phenolic resin powder and 6g of cashew shell oil are mixed evenly and stirred at 75°C for 25min to obtain a premix; 12g of nitrile rubber is added to the premix and kneaded at 125°C for 1.5h, and the mixture is discharged to obtain the nitrile rubber / cashew shell oil modified phenolic resin.

[0050] The preparation method of the octyltriethoxysilane modified nano-silica includes the following steps: S1. Disperse 50g of nano-silica with a particle size of 300nm in 150mL of anhydrous ethanol to obtain a silica dispersion. S2. Dissolve 5g of octyltriethoxysilane in 15mL of 80wt% ethanol solution, adjust the pH to 5.1, and obtain octyltriethoxysilane hydrolysate. S3. The octyltriethoxysilane hydrolysate is slowly added to the silica dispersion and reacted at 68°C for 7 hours. After solid-liquid separation and drying, the octyltriethoxysilane modified nano silica is obtained.

[0051] Example 2 This embodiment provides a friction material for brake pads and a brake pad prepared therefrom, comprising the following raw material components in parts by weight: 28 parts of nitrile rubber / cashew shell oil modified phenolic resin, 20 parts of styrene-butadiene rubber, 35 parts of basalt short fiber, 10 parts of wear-resistant aggregate, and 5 parts of rust inhibitor. The wear-resistant aggregate comprises the following raw material components by mass percentage: 15% wollastonite, 22% calcined red mud powder, 55% metakaolinite, and 8% molybdenum disulfide; the rust inhibitor comprises magnesium aluminum hydrotalcite, calcium hydroxide, and octyltriethoxysilane modified nano-silica in a mass ratio of 4:3:1.

[0052] The friction material for the brake pads includes the following steps: Step 1: Weigh each raw material component according to the design ratio, mix them evenly to obtain the mixture; Step 2: Heat the mixture to 158°C and hot press it at 30MPa to obtain a hot-pressed body; Step 3: The hot-pressed molded body is heated to 200°C for a second time and cured for 5 hours. After cooling, it is processed and shaped to obtain the brake pad precursor material. Step 4: Perform a short-term high-temperature surface ablation treatment on the brake pad precursor material at 550°C for 2 minutes to obtain the brake pad.

[0053] The preparation method of the nitrile rubber / cashew shell oil modified phenolic resin includes the following steps: 500g of phenolic resin powder and 6g of cashew shell oil are mixed evenly and stirred at 75°C for 25min to obtain a premix; 12g of nitrile rubber is added to the premix and kneaded at 125°C for 1.5h, and the mixture is discharged to obtain the nitrile rubber / cashew shell oil modified phenolic resin.

[0054] The preparation method of the octyltriethoxysilane modified nano-silica includes the following steps: S1. Disperse 50g of nano-silica with a particle size of 300nm in 150mL of anhydrous ethanol to obtain a silica dispersion. S2. Dissolve 5g of octyltriethoxysilane in 15mL of 80wt% ethanol solution, adjust the pH to 5.1, and obtain octyltriethoxysilane hydrolysate. S3. The octyltriethoxysilane hydrolysate is slowly added to the silica dispersion and reacted at 68°C for 7 hours. After solid-liquid separation and drying, the octyltriethoxysilane modified nano silica is obtained.

[0055] Example 3 This embodiment provides a friction material for brake pads and a brake pad prepared therefrom, comprising the following raw material components in parts by weight: 30 parts of nitrile rubber / cashew shell oil modified phenolic resin, 10 parts of styrene-butadiene rubber, 25 parts of basalt short fiber, 15 parts of wear-resistant aggregate, and 5 parts of rust inhibitor and corrosion inhibitor. The wear-resistant aggregate comprises the following raw material components by mass percentage: 20% wollastonite, 20% calcined red mud powder, 50% metakaolinite, and 10% molybdenum disulfide; the rust inhibitor comprises magnesium aluminum hydrotalcite, calcium hydroxide, and octyltriethoxysilane modified nano-silica in a mass ratio of 3:2:1.

[0056] The friction material for the brake pads includes the following steps: Step 1: Weigh each raw material component according to the design ratio, mix them evenly to obtain the mixture; Step 2: Heat the mixture to 160°C and hot press it at 28MPa to obtain a hot-pressed body; Step 3: The hot-pressed molded body is heated to 195°C for a second time and cured for 5 hours. After cooling, it is processed and shaped to obtain the brake pad precursor material. Step 4: Perform a short-term high-temperature surface ablation treatment on the brake pad precursor material at 550°C for 2 minutes to obtain the brake pad.

[0057] The preparation method of the nitrile rubber / cashew shell oil modified phenolic resin includes the following steps: 500g of phenolic resin powder and 6g of cashew shell oil are mixed evenly and stirred at 75°C for 25min to obtain a premix; 12g of nitrile rubber is added to the premix and kneaded at 125°C for 1.5h, and the mixture is discharged to obtain the nitrile rubber / cashew shell oil modified phenolic resin.

[0058] The preparation method of the octyltriethoxysilane modified nano-silica includes the following steps: S1. Disperse 50g of nano-silica with a particle size of 300nm in 150mL of anhydrous ethanol to obtain a silica dispersion. S2. Dissolve 5g of octyltriethoxysilane in 15mL of 80wt% ethanol solution, adjust the pH to 5.1, and obtain octyltriethoxysilane hydrolysate. S3. The octyltriethoxysilane hydrolysate is slowly added to the silica dispersion and reacted at 68°C for 7 hours. After solid-liquid separation and drying, the octyltriethoxysilane modified nano silica is obtained.

[0059] Comparative Example 1 This comparative example provides a friction material for brake pads and a brake pad prepared therefrom. The difference from Example 1 is that the nitrile rubber / cashew shell oil modified phenolic resin is replaced with an equal amount of cashew shell oil modified phenolic resin, while other components and contents remain unchanged, which will not be described in detail here.

[0060] Comparative Example 2 This comparative example provides a friction material for brake pads and a brake pad prepared therefrom. The difference from Example 1 is that the calcined red mud powder and molybdenum disulfide in the wear-resistant aggregate are replaced with an equal amount of dried red mud powder, while the other components and contents remain unchanged, which will not be described in detail here.

[0061] Comparative Example 3 This comparative example provides a friction material for brake pads and a brake pad prepared therefrom. The difference from Example 1 is that the octyltriethoxysilane-modified nano-silica in the rust inhibitor is replaced with an equal amount of hexadecyl phosphate-modified nano-silica. Other components and contents remain unchanged and will not be described in detail here.

[0062] The preparation method of the hexadecyl phosphate modified nano-silica includes the following steps: S1. Disperse 50g of nano-silica with a particle size of 300nm in 150mL of anhydrous ethanol to obtain a silica dispersion. S2. Dissolve 5g of hexadecyl phosphate in 15mL of 80wt% ethanol solution, adjust the pH to 5.1, and obtain hexadecyl phosphate hydrolysate. S3. The hexadecyl phosphate hydrolysate is slowly added to the silica dispersion and reacted at 68°C for 7 hours. After solid-liquid separation and drying, the hexadecyl phosphate modified nano silica is obtained.

[0063] To further demonstrate the technical effects of the present invention, the brake pads obtained in Example 1 and Comparative Examples 1-3 were tested as follows: the brake pads were tested on a JF151 constant speed friction testing machine, and the test results are shown in Table 1.

[0064] The rust adhesion test procedure is as follows: the speed is 250 r / min, and the brake is applied every 30 seconds to 0 r / min. After 30 test cycles, the brake and brake disc are immersed in 5 wt% salt water and taken out after 1 minute. The assembly and fastening are simulated on the actual vehicle with a clamping force of 17.5 KN. The brake disc is placed in a 5% salt spray chamber at a temperature of 35℃ and a humidity of 96% for 96 hours. The maximum pull-out force between the brake friction block and the brake disc after the test is shown in Table 2.

[0065] Table 1. Friction performance tests of brake pads obtained in Example 1 and Comparative Examples 1-3.

[0066] As can be seen from Table 1, the brake pad provided in Example 1 has a relatively stable coefficient of friction in the range of 100-350℃, and the wear amount at 100℃ is only 0.11mm and at 500℃ is only 0.14mm, indicating that the brake pad prepared by the present invention has very stable friction performance and excellent wear resistance.

[0067] Table 2. Rust-preventing and adhesion performance tests of brake pads obtained in Example 1 and Comparative Examples 1-3.

[0068] As can be seen from Table 2, the maximum disengagement torque between the brake friction block and the brake disc after the test of the brake pad obtained in Example 1 is much lower than that in Comparative Examples 1-3, indicating that Example 1 has the best anti-rust and bonding performance.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A friction material for brake pads, characterized in that, The raw material components include the following parts by weight: 20-30 parts of nitrile rubber / cashew shell oil modified phenolic resin, 10-20 parts of styrene-butadiene rubber, 20-40 parts of basalt short fiber, 10-15 parts of wear-resistant aggregate, and 3-5 parts of rust inhibitor and corrosion inhibitor. The wear-resistant aggregate includes wollastonite, calcined red mud powder, metakaolin, and molybdenum disulfide; the rust inhibitor includes magnesium aluminum hydrotalcite, calcium hydroxide, and octyltriethoxysilane-modified nano-silica.

2. The friction material for brake pads as described in claim 1, characterized in that, The wear-resistant aggregate comprises the following raw material components in the following mass percentages: 15%-20% wollastonite, 20%-30% calcined red mud powder, 50%-60% metakaolin, and 5-10% molybdenum disulfide.

3. The friction material for brake pads as described in claim 1, characterized in that, The rust inhibitor comprises magnesium aluminum hydrotalcite, calcium hydroxide, and octyltriethoxysilane-modified nano-silica in a mass ratio of 3:2:1 to 4:3:

1.

4. The friction material for brake pads as described in claim 1, characterized in that, The preparation method of the nitrile rubber / cashew shell oil modified phenolic resin includes the following steps: mixing phenolic resin and cashew shell oil evenly, stirring at 65-80℃ for 20-30 min to obtain a premix; adding nitrile rubber to the premix, kneading at 110-130℃ for 1-2 h, and discharging to obtain the nitrile rubber / cashew shell oil modified phenolic resin.

5. The friction material for brake pads as described in claim 1, characterized in that, The mass ratio of the phenolic resin, cashew nut shell oil, and nitrile rubber is 100:6:10-100:6:

15.

6. The friction material for brake pads as described in claim 1, characterized in that, The preparation method of the octyltriethoxysilane modified nano-silica includes the following steps: S1. Disperse nano-silica in anhydrous ethanol to obtain a silica dispersion; S2. Dissolve octyltriethoxysilane in an alcohol solution and adjust the pH to 4.8-5.2 to obtain octyltriethoxysilane hydrolysate; S3. The octyltriethoxysilane hydrolysate is slowly added to the silica dispersion and reacted at 65-70℃ for 6-8 hours. After solid-liquid separation and drying, the octyltriethoxysilane modified nano silica is obtained.

7. The friction material for brake pads as described in claim 6, characterized in that, In S1, the mass-to-volume ratio of the nano-silica to the anhydrous ethanol is 1g:3mL-1g:5mL; In S2, the mass-to-volume ratio of the octyltriethoxysilane to the alcohol solution is 1g:2mL-1g:3mL; wherein the alcohol solution is an ethanol solution with a mass fraction of 70%-80%. In S3, the mass ratio of the octyltriethoxysilane hydrolysate to the silica dispersion is 0.1:1-0.2:

1.

8. A brake pad, characterized in that, The brake pads are made using the friction material described in any one of claims 1-7.

9. A method for preparing a brake pad as described in claim 8, characterized in that, Includes the following steps: Step 1: Weigh each raw material component according to the design ratio, mix them evenly to obtain the mixture; Step 2: Heat the mixture to 150-165℃ and hot press it at 25-35MPa to obtain a hot-pressed body; Step 3: The hot-pressed molded body is heated to 180-210℃ for a second curing treatment, cooled, and processed into shape to obtain the brake pad precursor material; Step 4: Perform a short-term high-temperature surface ablation treatment on the brake pad precursor material at 520-580℃ to obtain the brake pad.

10. The application of the brake pad as described in claim 8 in the field of automobile manufacturing.

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