A friction material for brake pads and its preparation method

Abstract

The present invention discloses a friction material for brake pads, which relates to the technical field of friction materials. The friction material is made of the following components by weight: 15-35 parts of cashew shell oil modified phenolic resin, 2-10 parts of aramid fiber, 10-20 parts of graphite, 6-12 parts of modified basalt fiber, 4-16 parts of glass fiber, 4-8 parts of rubber powder, 3-6 parts of silicon nitride, 2-4 parts of sepiolite, 5-15 parts of barium sulfate, 3-6 parts of zircon powder, and 2-10 parts of alumina. Through the synergistic effect of each component and the optimization of the interface bonding characteristics, the prepared friction material improves the noise and vibration problems during the braking process. At the same time, it can maintain stable friction coefficient and wear rate within a wide temperature range, effectively reducing the performance degradation under high-temperature conditions and extending the service life of the brake pads.

Description

Technical Field

[0001] The present invention relates to the technical field of friction materials, and particularly relates to a friction material for brake pads and a preparation method thereof. Background Art

[0002] Brake pads are key functional components in the automotive braking system that convert kinetic energy into heat energy, and achieve vehicle deceleration or stop through the frictional interaction with the brake disc (or brake drum). Its working principle is that under the action of the hydraulic system, the friction block is in close contact with the rotating brake disc, generating frictional force to counteract the rotation of the wheel. The performance of brake pads is directly related to braking distance, braking stability and comfort, and is a core component to ensure driving safety.

[0003] As the main part of brake pads, friction materials usually consist of four categories: matrix materials, reinforcing materials, friction modifiers and fillers. Matrix materials provide necessary structural support and bonding functions; reinforcing materials increase mechanical strength and wear resistance; friction modifiers stabilize the friction coefficient; fillers are used to adjust density, thermal conductivity and cost. High-quality friction materials need to meet multiple requirements such as high friction coefficient, low wear rate, high thermal stability, low noise and vibration, and environmental friendliness, and these performances need to remain relatively stable within a wide temperature range of -40°C to 800°C.

[0004] Traditional brake pad friction materials are mainly divided into three categories: organic type, semi-metallic type and ceramic type. Organic friction materials usually use phenolic resin as the matrix, and are composed of adding fiber reinforcing materials, friction modifiers, fillers and lubricants, etc.; a certain proportion of metal powder or fiber is added to semi-metallic friction materials to improve the heat resistance and wear resistance of the materials; ceramic friction materials use ceramic materials as the main component and have the characteristics of good high-temperature stability.

[0005] The key factors affecting the performance of friction materials include material formula, microstructure and preparation process. Among them, the interfacial bonding strength of materials determines the overall mechanical properties of the composite material; the formation and stability of the surface friction transfer film affect the friction coefficient; the construction of the heat diffusion path is related to the degree of high-temperature decline. In practical applications, working conditions such as frequent start-stop, high-speed heavy load and harsh environment put forward higher requirements for materials, and friction materials need to maintain stable performance under these complex conditions.

[0006] However, existing brake pad friction materials face multiple technical problems in practical applications: one is that the friction coefficient changes significantly with temperature, and the friction performance deteriorates severely at high temperatures, leading to the risk of "brake failure"; the second is that the problems of noise and vibration generated during the friction process are prominent, affecting the ride comfort; the third is that the wear rate of the friction material is relatively high and the service life is limited; the fourth is that the compatibility between the friction material and the brake disc is poor, resulting in excessive wear of the brake disc; the fifth is that traditional formulations often contain components harmful to the environment and health, such as asbestos, heavy metals, etc.

[0007] To solve the above problems, researchers have been continuously exploring new materials and process routes. Among them, asbestos-free environmentally friendly formulations, high-temperature stability formulations, and composite materials with self-lubricating properties have become research hotspots. In particular, enhancing the bonding force between fibers and the matrix through interface modification technology and introducing modified fillers with special functions have become important ways to improve the comprehensive performance of friction materials. The industry development trend gradually focuses on three major directions: nano-composite reinforcement, interface regulation technology, and functional modification, in order to achieve the decoupling of the friction coefficient and temperature and adaptive friction characteristics.

[0008] CN109505901A discloses a friction material containing aramid fibers and a preparation method of a friction material component, which relates to the technical field of friction materials. The friction material containing aramid fibers of the present invention is made of the following raw materials: mineral fibers, aramid fibers, friction powder, nitrile rubber powder, petroleum coke, zircon powder, vermiculite, barite, artificial graphite, light calcium carbonate, resin, graphite. However, the interfacial bonding between the fibers and the matrix is weak, affecting the durability of the material.

[0009] Therefore, developing a brake pad friction material with good high-temperature stability, low noise, strong wear resistance and environmental protection is of great significance for improving the safety, reliability and comfort of automotive braking systems. Summary of the Invention

[0010] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a friction material for brake pads and its preparation method. Through the synergistic effect of each component and the optimization of the interfacial bonding characteristics, the friction material improves the noise and vibration problems during braking, and at the same time can maintain stable friction coefficients and wear rates within a wide temperature range, effectively reducing the performance degradation under high-temperature conditions and extending the service life of brake pads.

[0011] To achieve the above purpose, the present invention adopts the following technical solutions:

[0012] A friction material for brake pads is made of the following components by weight: 15-35 parts of cashew shell oil modified phenolic resin, 2-10 parts of aramid fiber, 10-20 parts of graphite, 6-12 parts of modified basalt fiber, 4-16 parts of glass fiber, 4-8 parts of rubber powder, 3-6 parts of silicon nitride, 2-4 parts of sepiolite, 5-15 parts of barium sulfate, 3-6 parts of zircon powder, 2-10 parts of alumina.

[0013] Preferably, the preparation method of the modified basalt fiber includes the following steps:

[0014] (1) Ultrasonically clean the basalt fibers successively with acetone and hydrochloric acid, then immerse them in an ethanol aqueous solution, add KH550, adjust the pH of the system, stir and react, filter, wash with alcohol, and dry the product to obtain amino-functionalized fibers.

[0015] Preparation of amino-functionalized fibers: The silanol groups on the surface of basalt fibers undergo hydrolysis and condensation with KH550 (γ-aminopropyltriethoxysilane) in an acidic ethanol solution. The triethoxysilyl groups of KH550 hydrolyze to form silanols, which then condense with the silanol groups on the fiber surface to form covalent bonds (Si-O-Si), and the terminal amino groups are exposed on the fiber surface.

[0016] Preferably, in step (1), ultrasonically clean for 30 - 60 min; adjust the pH of the system to 4 - 5 with glacial acetic acid; the stirring reaction conditions are to stir and react at 60 - 75 °C for 5 - 8 h.

[0017] Preferably, in step (1), the dosage ratio of basalt fibers, ethanol aqueous solution, and KH550 is 10 g : 150 - 200 mL : 0.2 - 1 g; the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 8 - 9 : 1 - 2.

[0018] (2) Immerse the amino-functionalized fibers in ethylene glycol dimethyl ether, then add 4-nonylphenyl glycidyl ether and triethylamine, stir and react, filter, wash, and dry the product to obtain intermediate fibers.

[0019] Ring-opening grafting of epoxy groups: The primary amino groups of the amino-functionalized fibers act as nucleophiles and attack the epoxy groups of the glycidyl ether under alkaline catalytic conditions. The reaction proceeds through the SN2 mechanism: The amino group attacks the methylene carbon of the epoxy ring, resulting in ring opening and the formation of secondary amine bonds, while generating hydroxyl groups. The catalyst accelerates the reaction process by capturing protons and retains some amino active sites by controlling the reactant ratio.

[0020] Preferably, in step (2), the dosage ratio of amino-functionalized fibers, ethylene glycol dimethyl ether, 4-nonylphenyl glycidyl ether, and triethylamine is 10 g : 100 - 150 mL : 1 - 3 g : 0.1 - 0.4 g.

[0021] Preferably, in step (2), the stirring reaction conditions are to stir and react at 40 - 55 °C for 9 - 12 h.

[0022] (3) Add the intermediate fibers and 1,1'-ferrocene dicarboxylic acid to N,N-dimethylacetamide, then add EDC and NHS, stir and react, filter, wash, and freeze-dry the product to obtain the modified basalt fibers.

[0023] Ferrocene formic acid grafting: EDC and NHS synergistically activate the carboxyl group of ferrocene formic acid. EDC reacts with carboxylic acid to form a highly reactive intermediate, and then NHS substitutes to form a stable ester derivative. This activated ester undergoes nucleophilic substitution with the residual amino groups on the fiber surface to form amide bonds.

[0024] Preferably, in step (3), the dosage ratio of intermediate fiber, 1,1'-ferrocene dicarboxylic acid, N,N-dimethylacetamide, EDC, and NHS is 10 g: 2.5 - 5 g: 100 - 150 mL: 1 - 2 g: 0.5 - 1 g.

[0025] Preferably, in step (3), the stirring reaction conditions are stirring and reacting at 25 - 40 °C for 18 - 24 h.

[0026] The present invention also claims to protect a preparation method of the friction material for brake pads, comprising the following steps: putting each raw material into a mixer and mixing evenly to obtain a mixture; hot pressing and molding the mixture to obtain a preform; drying the preform and then keeping it warm to obtain the friction material for brake pads.

[0027] Preferably, the main shaft rotation speed of the mixer is 150 - 200 r / min, the reamer rotation speed is 2000 - 2600 r / min, and the mixing time is 150 - 250 s; the hot pressing conditions are pressing at 150 - 180 °C and 8 - 12 MPa for 8 - 16 min; the heat preservation conditions are keeping warm at 150 - 180 °C for 8 - 14 h.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention provides a friction material for brake pads, and the performance is optimized through the synergistic effect of each component: Cashew shell oil modified phenolic resin is used as the matrix material, forming a stable three-dimensional cross-linked network at high temperature, endowing the material with excellent heat resistance and mechanical support; the synergistic reinforcement of aramid fiber and glass fiber significantly improves the shear resistance, and together with the rigid framework structure of modified basalt fiber, effectively improves the overall bending resistance of the material; graphite and silicon nitride form a complementary lubrication system, reducing the performance fluctuation during the friction process; the porous characteristics of sepiolite and zircon powder can adsorb thermal decomposition products and delay the high-temperature decline; rubber powder buffers vibration energy through elastic deformation and reduces braking noise. The gradient distribution of hard fillers (such as alumina, barium sulfate, etc.) optimizes the microscopic structure of the friction interface and maintains stable friction coefficient and wear characteristics within a wide temperature range.

[0030] 2. The present invention provides a modified basalt fiber, which endows the basalt fiber with multi-dimensional reinforcement characteristics through three-step chemical modification: the organic modification with KH550 introduces organic groups on the fiber surface, which can significantly improve the interfacial compatibility and bonding strength with the resin matrix; the long-chain alkyl structure of 4-nonylphenyl glycidyl ether enhances the physical interlocking effect between the fiber and the resin through the molecular entanglement effect. Its rigid benzene ring skeleton not only improves the overall toughness of the material, but also optimizes the stress transfer path through π-π interaction; the thermal stability of the grafted benzene ring can also improve the moisture and heat resistance of the friction material and inhibit interface failure under high-temperature environments; the introduced ferrocene group forms a dynamic redox interface layer during the friction process. While stabilizing the friction coefficient through the charge migration effect, its coordinated metal center can cooperate with the lubricating component to form a self-lubricating transfer film, further inhibiting the adhesive wear of the friction pair. The basalt fiber has the triple functional characteristics of interface strengthening, thermal stability improvement and friction dynamic response. Detailed implementation manners

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in detail with reference to the embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Unless otherwise specified, the chemical reagents and materials in the present invention are all purchased through market channels or synthesized from raw materials purchased through market channels.

[0033] The cashew shell oil modified phenolic resin is purchased from Cardolite Corporation, with the model NX-5341;

[0034] The aramid fiber has a diameter of 12 μm and a length of 2 - 6 mm;

[0035] The graphite is purchased from Hubei Jueneng Graphite Co., Ltd., with the brand number 7206A;

[0036] The basalt fiber is 12 μm in diameter and 4 - 10 mm in length;

[0037] The glass fiber is 3 - 6 mm alkali-free glass fiber, purchased from Tongxiang Jushi Group Co., Ltd.;

[0038] The rubber powder has a rubber content of 90 - 95% and a tensile strength of 4.5 MPa, purchased from Lingshou County Miaoxin Mineral Products Processing Factory;

[0039] The sepiolite is purchased from Shijiazhuang Leisheng Mineral Products Co., Ltd.;

[0040] The barium sulfate has a particle size of 200 - 325 mesh, purchased from Shanxi Nanfeng Group Co., Ltd.;

[0041] The alumina has a particle size of 200 - 325 mesh, purchased from Hangzhou Xiaoshan Great Wall Aluminum Industry Materials Co., Ltd.

[0042] A preparation method of a friction material for brake pads, comprising the following steps:

[0043] (1) Ultrasonically clean 10 g of basalt fibers successively with 150 mL of acetone and 150 mL of 0.1 mol / L hydrochloric acid for 45 min, then immerse them in 200 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 8 - 9:1 - 2), add 0.2 - 1 g of KH550, adjust the pH of the system to 4 - 5 with glacial acetic acid, stir and react at 60 - 75 °C for 5 - 8 h, filter, wash with alcohol, and dry the product to obtain amino-functionalized fibers;

[0044] (2) Immerse 10 g of amino-functionalized fibers in 100 - 150 mL of ethylene glycol dimethyl ether, then add 1 - 3 g of 4-nonylphenyl glycidyl ether and 0.1 - 0.4 g of triethylamine, stir and react at 40 - 55 °C for 9 - 12 h, filter, wash, and dry the product to obtain intermediate fibers;

[0045] (3) Add 10 g of intermediate fibers and 2.5 - 5 g of 1,1'-ferrocene dicarboxylic acid to 100 - 150 mL of N,N-dimethylacetamide, then add 1 - 2 g of EDC and 0.5 - 1 g of NHS, stir and react at 25 - 40 °C for 18 - 24 h, filter, wash, and freeze-dry the product to obtain the modified basalt fibers;

[0046] (4) Put 15 - 35 parts of cashew shell oil modified phenolic resin, 2 - 10 parts of aramid fiber, 10 - 20 parts of graphite, 6 - 12 parts of modified basalt fibers, 4 - 16 parts of glass fiber, 4 - 8 parts of rubber powder, 3 - 6 parts of silicon nitride, 2 - 4 parts of sepiolite, 5 - 15 parts of barium sulfate, and 3 - 6 parts of zircon powder, and 2 - 10 parts of alumina into a mixer. The main shaft speed of the mixer is 180 r / min, the reamer speed is 2400 r / min, and the mixing time is 200 s to obtain a mixture; press and thermoform it at 160 °C and 10 MPa for 12 min to obtain a preform; dry the preform and keep it at 160 °C for 12 h to obtain the friction material for brake pads.

[0047] The following is a further description of the present invention through specific examples.

[0048] Example 1

[0049] A preparation method of a friction material for brake pads, comprising the following steps:

[0050] (1) Ultrasonically clean 10 g of basalt fibers successively with 150 mL of acetone and 150 mL of 0.1 mol / L hydrochloric acid for 45 min, then immerse them in 200 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 1 g of KH550, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 75 °C for 5 h, filter, wash with alcohol, and dry the product to obtain amino-functionalized fibers;

[0051] (2) Immerse 10 g of amino-functionalized fibers in 120 mL of ethylene glycol dimethyl ether, then add 3 g of 4-nonylphenyl glycidyl ether and 0.4 g of triethylamine, stir and react at 55 °C for 9 h, filter, wash, and dry the product to obtain intermediate fibers;

[0052] (3) Add 10 g of intermediate fibers and 5 g of 1,1'-ferrocene dicarboxylic acid to 120 mL of N,N-dimethylacetamide, then add 2 g of EDC and 1 g of NHS, stir and react at 40 °C for 18 h, filter, wash, and freeze-dry the product to obtain the modified basalt fibers;

[0053] (4) Put 350 g of cashew shell oil-modified phenolic resin, 100 g of aramid fiber, 200 g of graphite, 120 g of modified basalt fibers, 160 g of glass fiber, 80 g of rubber powder, 60 g of silicon nitride, 40 g of sepiolite, 150 g of barium sulfate, 60 g of zircon powder, and 100 g of alumina into a mixer. The main shaft speed of the mixer is 180 r / min, the speed of the reamer is 2400 r / min, and the mixing time is 200 s to obtain a mixture; press and thermoform it at 160 °C and 10 MPa for 12 min to obtain a preform; dry the preform and keep it at 160 °C for 12 h to obtain the friction material for brake pads.

[0054] Example 2

[0055] A preparation method of a friction material for brake pads, comprising the following steps:

[0056] (1) Ultrasonically clean 10 g of basalt fibers successively with 150 mL of acetone and 150 mL of 0.1 mol / L hydrochloric acid for 45 min, then immerse them in 200 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 0.8 g of KH550, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 70 °C for 6 h, filter, wash with alcohol, and dry the product to obtain amino-functionalized fibers;

[0057] (2) Immerse 10 g of amino-functionalized fibers in 120 mL of ethylene glycol dimethyl ether, then add 2 g of 4-nonylphenyl glycidyl ether and 0.3 g of triethylamine, stir and react at 50 °C for 10 h, filter, wash, and dry the product to obtain intermediate fibers;

[0058] (3) Add 10 g of intermediate fiber and 4 g of 1,1'-ferrocene dicarboxylic acid to 120 mL of N,N-dimethylacetamide, then add 1.5 g of EDC and 0.7 g of NHS, and stir and react at 35 °C for 20 h. Filter, wash, and freeze-dry the product to obtain the modified basalt fiber;

[0059] (4) Put 300 g of cashew shell oil-modified phenolic resin, 80 g of aramid fiber, 180 g of graphite, 100 g of modified basalt fiber, 120 g of glass fiber, 60 g of rubber powder, 50 g of silicon nitride, 30 g of sepiolite, 120 g of barium sulfate, 50 g of zircon powder, and 80 g of alumina into a mixer. The main shaft speed of the mixer is 180 r / min, the reamer speed is 2400 r / min, and the mixing time is 200 s to obtain a mixture; press and thermoform it at 160 °C and 10 MPa for 12 min to obtain a preform; dry the preform and keep it warm at 160 °C for 12 h to obtain the friction material for brake pads.

[0060] Example 3

[0061] A preparation method of a friction material for brake pads, comprising the following steps:

[0062] (1) Ultrasonically clean 10 g of basalt fiber with 150 mL of acetone and 150 mL of 0.1 mol / L hydrochloric acid for 45 min in sequence, then immerse it in 200 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 0.4 g of KH550, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 65 °C for 7 h, filter, wash with alcohol, and dry the product to obtain amino-functionalized fiber;

[0063] (2) Immerse 10 g of amino-functionalized fiber in 120 mL of ethylene glycol dimethyl ether, then add 1.2 g of 4-nonylphenyl glycidyl ether and 0.2 g of triethylamine, stir and react at 45 °C for 11 h, filter, wash, and dry the product to obtain intermediate fiber;

[0064] (3) Add 10 g of intermediate fiber and 3 g of 1,1'-ferrocene dicarboxylic acid to 120 mL of N,N-dimethylacetamide, then add 1.2 g of EDC and 0.6 g of NHS, stir and react at 30 °C for 22 h, filter, wash, and freeze-dry the product to obtain the modified basalt fiber;

[0065] (4) Put 200 g of cardanol-modified phenolic resin, 40 g of aramid fiber, 120 g of graphite, 80 g of modified basalt fiber, 60 g of glass fiber, 50 g of rubber powder, 40 g of silicon nitride, 30 g of sepiolite, 80 g of barium sulfate, 40 g of zircon powder, and 40 g of alumina into a mixer. The main shaft speed of the mixer is 180 r / min, the reamer speed is 2400 r / min, and the mixing time is 200 s to obtain a mixture. Press and thermoform it at 160 °C and 10 MPa for 12 min to obtain a preform. After drying the preform, keep it at 160 °C for 12 h to obtain the friction material for brake pads.

[0066] Example 4

[0067] A preparation method of a friction material for brake pads, comprising the following steps:

[0068] (1) Ultrasonically clean 10 g of basalt fiber with 150 mL of acetone and 150 mL of 0.1 mol / L hydrochloric acid for 45 min in sequence, then immerse it in 200 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 0.2 g of KH550, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 60 °C for 8 h, filter, wash with alcohol, and dry the product to obtain amino-functionalized fiber.

[0069] (2) Immerse 10 g of amino-functionalized fiber in 120 mL of ethylene glycol dimethyl ether, then add 1 g of 4-nonylphenyl glycidyl ether and 0.1 g of triethylamine, stir and react at 40 °C for 12 h, filter, wash, and dry the product to obtain intermediate fiber.

[0070] (3) Add 10 g of intermediate fiber and 2.5 g of 1,1'-ferrocene dicarboxylic acid to 120 mL of N,N-dimethylacetamide, then add 1 g of EDC and 0.5 g of NHS, stir and react at 25 °C for 24 h, filter, wash, and freeze-dry the product to obtain the modified basalt fiber.

[0071] (4) Put 150 g of cardanol-modified phenolic resin, 20 g of aramid fiber, 100 g of graphite, 60 g of modified basalt fiber, 40 g of glass fiber, 40 g of rubber powder, 30 g of silicon nitride, 20 g of sepiolite, 50 g of barium sulfate, 30 g of zircon powder, and 20 g of alumina into a mixer. The main shaft speed of the mixer is 180 r / min, the reamer speed is 2400 r / min, and the mixing time is 200 s to obtain a mixture. Press and thermoform it at 160 °C and 10 MPa for 12 min to obtain a preform. After drying the preform, keep it at 160 °C for 12 h to obtain the friction material for brake pads.

[0072] Comparative Example 1

[0073] A preparation method of a friction material, comprising the following steps:

[0074] (1) Ultrasonically clean 10 g of basalt fibers successively with 150 mL of acetone and 150 mL of 0.1 mol / L hydrochloric acid for 45 min, then immerse them in 200 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 1 g of KH550, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 75 °C for 5 h, filter, wash with alcohol, and dry the product to obtain amino-functionalized fibers;

[0075] (2) Immerse 10 g of amino-functionalized fibers in 120 mL of ethylene glycol dimethyl ether, then add 3 g of 4-nonylphenyl glycidyl ether and 0.4 g of triethylamine, stir and react at 55 °C for 9 h, filter, wash, and dry the product to obtain intermediate fibers;

[0076] (3) Put 350 g of cashew shell oil-modified phenolic resin, 100 g of aramid fiber, 200 g of graphite, 120 g of intermediate fibers, 160 g of glass fiber, 80 g of rubber powder, 60 g of silicon nitride, 40 g of sepiolite, 150 g of barium sulfate, 60 g of zircon powder, and 100 g of alumina into a mixer. The main shaft speed of the mixer is 180 r / min, the reamer speed is 2400 r / min, and the mixing time is 200 s to obtain a mixture; hot press and mold it at 160 °C and 10 MPa for 12 min to obtain a preform; dry the preform and keep it at 160 °C for 12 h to obtain the friction material.

[0077] Comparative Example 2

[0078] A preparation method of a friction material, comprising the following steps:

[0079] (1) Ultrasonically clean 10 g of basalt fibers successively with 150 mL of acetone and 150 mL of 0.1 mol / L hydrochloric acid for 45 min, then immerse them in 200 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 9:1), add 1 g of KH550, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 75 °C for 5 h, filter, wash with alcohol, and dry the product to obtain amino-functionalized fibers;

[0080] (2) Put 350 g of cashew nut shell oil modified phenolic resin, 100 g of aramid fiber, 200 g of graphite, 120 g of aminated fiber, 160 g of glass fiber, 80 g of rubber powder, 60 g of silicon nitride, 40 g of sepiolite, 150 g of barium sulfate, 60 g of zircon powder, and 100 g of alumina into a mixer. The main shaft speed of the mixer is 180 r / min, the reamer speed is 2,400 r / min, and the mixing time is 200 s to obtain a mixture; press and hot-mold it at 160 °C and 10 MPa for 12 min to obtain a preform; dry the preform and keep it at 160 °C for 12 h to obtain the friction material.

[0081] Perform performance tests on the friction materials prepared in Examples 1 to 4 and Comparative Examples 1 to 2. Refer to GB / T 33835-2017 "Test Method for Impact Strength of Friction Materials" to test their impact strength, refer to GB 5763-2018 "Brake Linings for Motor Vehicles" to test their friction coefficient and wear rate, refer to SAE J2468-2018 "Test Procedure for Compressibility of Brake Pads for Road Vehicles" to test their normal temperature (25 °C) compression variable and hot compression variable, and use an AWA6128A type standing wave tube sound absorption coefficient tester to test the sound absorption coefficient. The specific data is shown in Table 1.

[0082] Table 1 Test Results of Friction Material Performance

[0083]

[0084] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A friction material for a brake pad, characterized in that: The invention is prepared from the following components by weight: 15-35 parts of cashew nut shell oil modified phenolic resin, 2-10 parts of aramid fiber, 10-20 parts of graphite, 6-12 parts of modified basalt fiber, 4-16 parts of glass fiber, 4-8 parts of rubber powder, 3-6 parts of silicon nitride, 2-4 parts of sepiolite, 5-15 parts of barium sulfate, 3-6 parts of zircon powder and 2-10 parts of alumina; The preparation method of the modified basalt fiber comprises the following steps: (1) The basalt fiber is ultrasonically cleaned with acetone and hydrochloric acid in sequence, then immersed in an ethanol aqueous solution, KH550 is added, the pH of the system is adjusted, the reaction is stirred, and the product is filtered, washed with alcohol, and dried to obtain an amino fiber; (2) immersing the amino fiber in ethylene glycol dimethyl ether, then adding 4-nonylbenzene glycidyl ether and triethylamine, stirring to react, filtering, washing, and drying the product to obtain an intermediate fiber; (3) adding the intermediate fiber and 1,1'-ferrocenecarboxylic acid to N,N-dimethylacetamide, then adding EDC and NHS, stirring to react, filtering, washing, and freeze-drying the product to obtain the modified basalt fiber.

2. The friction material for brake pads according to claim 1, characterized in that: In step (1), ultrasonic cleaning is performed for 30 to 60 minutes; the pH value of the system is adjusted to 4 to 5 with glacial acetic acid; and the stirring reaction conditions are 60 to 75° C. and the stirring reaction is performed for 5 to 8 hours.

3. The friction material for brake pads according to claim 1, characterized in that: In step (1), the usage ratio of basalt fiber, ethanol aqueous solution and KH550 is 10 g: 150-200 mL: 0.2-1 g; the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 8-9: 1-2.

4. The friction material for brake pads according to claim 1, characterized in that: In step (2), the usage ratio of amino fiber, ethylene glycol dimethyl ether, 4-nonylbenzene glycidyl ether and triethylamine is 10 g: 100-150 mL: 1-3 g: 0.1-0.4 g.

5. The friction material for brake pads according to claim 1, characterized in that: In step (2), the stirring reaction conditions are 40-55° C. for 9-12 h.

6. The friction material for brake pads according to claim 1, characterized in that: In step (3), the usage ratio of the intermediate fiber, 1,1'-ferrocenecarboxylic acid, N,N-dimethylacetamide, EDC, and NHS is 10 g: 2.5-5 g: 100-150 mL: 1-2 g: 0.5-1 g.

7. The friction material for brake pads according to claim 1, characterized in that: In step (3), the stirring reaction conditions are 25-40° C. and 18-24 h.

8. A method for preparing a friction material for a brake pad as claimed in any one of claims 1 to 7, characterized in that: The method comprises the following steps: putting various raw materials into a mixer and mixing them evenly to obtain a mixture; hot pressing the mixture to obtain a preform; and drying and heat-insulating the preform to obtain the friction material for the brake pad.

9. The preparation method according to claim 8, characterized in that: The main shaft speed of the mixer is 150~200r / min, the reamer speed is 2000~2600r / min, and the mixing time is 150~250s; the hot pressing conditions are 150~180℃, 8~12MPa for 8~16min; the insulation conditions are 150~180℃ for 8~14h.

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