A friction material composition, a method for producing a friction material, and an application thereof

Abstract

This disclosure provides a friction material composition, a method for preparing the friction material, and its application, relating to the field of automotive parts technology, to solve the problems of poor wear resistance and poor high-temperature resistance of friction materials. The friction material composition includes a resin binder and a paper base. The resin binder includes a phenolic resin, an epoxy resin, nitrile rubber, and a solvent. The mass ratio of the solid solute in the phenolic resin, the solid solute in the epoxy resin, the nitrile rubber, and the solvent is (25-45):(2-10):(2-10):(40-60). The method for preparing the friction material includes the friction material composition described above. The friction material composition provided in this disclosure is used to prepare friction materials.

Description

Technical Field

[0001] This disclosure relates to the field of automotive parts technology, and in particular to a friction material composition, a method for preparing the friction material, and its application. Background Technology

[0002] Wet paper-based friction materials are typically made by bonding fibers and fillers together using phenolic resin as a binder. The properties of the binder directly affect the flexibility, heat resistance, and tribological properties of the friction material. However, the resin binders used in related technologies are brittle, resulting in friction materials with high hardness and poor toughness. These materials are prone to cracking at the interfaces of various raw materials, exhibiting poor wear resistance and heat resistance, showing significant oxidation at temperatures exceeding 250°C. Summary of the Invention

[0003] The purpose of this disclosure is to provide a friction material composition, a method for preparing a friction material, and its application, for the preparation of friction materials.

[0004] To achieve the above objectives, this disclosure provides the following technical solution: a friction material composition comprising a resin binder and a papermaking base paper, wherein the resin binder comprises a new phenolic resin, an epoxy resin, a nitrile rubber, and a solvent, and the mass ratio of the solid solute in the new phenolic resin, the solid solute in the epoxy resin, the nitrile rubber, and the solvent is (25-45):(2-10):(2-10):(40-60).

[0005] Compared with the prior art, the friction material composition provided in this disclosure is prepared by using a resin binder and a paper substrate. The resin binder includes a new phenolic resin, an epoxy resin, nitrile rubber, and a solvent. Since the new phenolic resin is in a liquid state at 25°C, the liquid state of the new phenolic resin is beneficial to improving the wettability of the resin in the substrate, resulting in a tight bond between the paper substrate and the resin interface, and giving the substrate good shear strength and toughness. At the same time, by selecting an epoxy resin that meets the above-mentioned mass ratio requirements to modify the new phenolic resin, the hydroxymethyl groups in the new phenolic resin react chemically with the hydroxyl and epoxy groups in the epoxy resin, and the phenolic hydroxyl groups in the phenolic resin react chemically with the epoxy groups in the epoxy resin, finally crosslinking into a complex and stable three-dimensional structure, giving the mixture the excellent adhesion and toughness of epoxy resin and the excellent heat resistance of new phenolic resin. By selecting nitrile rubber that meets the above-mentioned mass ratio requirements to modify the new phenolic resin, the nitrile rubber molecular backbone has many cyano groups as side groups. The cyano groups have high reactivity and can be hydrolyzed into amide or carboxyl groups under acidic or alkaline conditions. These active groups can form hydrogen bonds with the hydrogen elements in the new phenolic resin molecules, improving the compatibility and bonding force between the phenolic resin and nitrile rubber, and also increasing the strength and density of the mixture, thus enhancing the substrate's resistance to friction and wear. Furthermore, the flowability of the new phenolic resin modified with epoxy resin and nitrile rubber is improved, further enhancing its wetting ability.

[0006] When the above-mentioned resin binder is used to prepare friction materials, the prepared friction materials can maintain the stability of their structure at high temperatures, have low expansion performance, good toughness, and high mechanical strength.

[0007] This disclosure also provides a method for preparing a friction material, which is obtained by hot pressing the above-mentioned friction material composition.

[0008] Compared with the prior art, the beneficial effects of the friction material preparation method provided in this disclosure are the same as the beneficial effects of the friction material composition described in the above technical solution, and will not be repeated here.

[0009] This disclosure also provides an application of a friction material composition in a gearbox.

[0010] Compared with the prior art, the beneficial effects of the friction material composition provided in this disclosure in the application of the gearbox are the same as the beneficial effects of the friction material composition described in the above-mentioned technical solutions, and will not be repeated here. Attached Figure Description

[0011] The accompanying drawings, which are included to provide a further understanding of this disclosure and form part of this disclosure, illustrate exemplary embodiments of the present disclosure and are used to explain the disclosure, but do not constitute an undue limitation of the disclosure. In the drawings:

[0012] Figure 1 A flowchart illustrating a method for preparing a friction material according to an exemplary embodiment of the present disclosure is shown. Detailed Implementation

[0013] To make the technical problems, technical solutions, and beneficial effects to be solved by this disclosure clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this disclosure and are not intended to limit it.

[0014] Friction materials utilize friction for braking or power transmission. Wet friction materials are one type of product, with a key downstream application being gearboxes (transmissions), where they use friction to synchronize speed differences. Gearbox friction materials are wet paper-based friction materials, operating by immersing themselves in various oils to transmit power.

[0015] Friction materials are characterized by good friction coefficients and wear resistance, while also possessing certain heat resistance and mechanical strength, meeting the performance requirements of vehicle or machinery transmission and braking. Wet paper-based friction materials are the mainstream wet friction materials used in automatic transmissions. They are composite materials made from paper as the base, fibers as reinforcement, and polymer materials as resin binders, with added friction modifiers. They possess a network-like porous structure that can store lubricating oil within the pores, offering advantages such as high friction coefficient, stable friction performance, good wear resistance, strong power transmission capability, and low noise. The resin binder used in friction materials is primarily phenolic resin, which softens into a viscous state at certain temperatures. Through molding and rubber vulcanization, the fibers and fillers are bonded together, forming a dense friction product with considerable strength, meeting the performance requirements of wear-resistant, high-temperature resistant, flexible, and corrosion-resistant materials. Therefore, the resin binder is the most critical matrix component in friction materials. It binds various components tightly together to achieve the desired properties, and its performance directly affects the performance of friction materials, especially its temperature resistance, which determines the performance of the friction material in use. The high-temperature resistance of the resin binder directly determines the heat fade resistance of the friction pad; therefore, the development of high-temperature resistant resins is key to the research and development of high-performance friction pads. This requires the resin binder to withstand high temperatures, maintaining its structural integrity and dimensional stability even at 350℃; it also requires high bonding strength, good compatibility with various organic or inorganic fiber fillers, fast wetting speed, and, after cross-linking, to provide the friction material with mechanical strength, toughness, and other properties.

[0016] However, the inventors discovered that the resin binder used in the related technology is brittle, resulting in friction products with high hardness and poor toughness. These products are prone to cracking at the interfaces of various raw materials and exhibit poor heat resistance, beginning to oxidize significantly at temperatures exceeding 250°C. Friction materials prepared using this resin binder exhibit poor flexibility, heat resistance, and wear resistance. Furthermore, the resin binder has poor wettability with fiber fillers. If multiple layers of base paper are hot-pressed, the interlaminar shear strength of the composite substrate is poor, easily leading to delamination. Simultaneously, the resin is distributed in flake or block form within the matrix, thus clogging pores to some extent and significantly reducing the porosity and permeability of the substrate. On the other hand, friction materials hot-pressed using this type of resin binder tend to be brittle and hard, with poor toughness, prone to cracking, poor compression resilience, and poor heat resistance.

[0017] To overcome the above problems, an exemplary embodiment of this disclosure provides a friction material composition, and the friction material prepared using this friction material composition has excellent properties such as good heat resistance, good toughness, wear resistance and high mechanical strength.

[0018] The aforementioned friction material composition includes a resin binder and a paper base. It should be understood that the paper base involved in the exemplary embodiments of this disclosure can be prepared by a wet papermaking process from plant fibers, carbon fibers, aramid fibers, inorganic fibers, graphite, diatomaceous earth, alumina, and friction modifiers, etc. Of course, other paper bases can also be used, and no limitation is made herein.

[0019] The aforementioned resin adhesives include neophenolic resin, epoxy resin, nitrile rubber, and solvents. Epoxy resin has the lowest curing shrinkage rate (1%–2%) among resin adhesives and also has a low coefficient of thermal expansion (6.0 × 10⁻⁶). -5 / ℃). By chemically reacting the hydroxymethyl groups in the new phenolic resin with the hydroxyl and epoxy groups in the epoxy resin, and the phenolic hydroxyl groups in the new phenolic resin with the epoxy groups in the epoxy resin, a complex and stable three-dimensional structure is finally cross-linked. This allows for the introduction of more functional groups and different molecular chain structures into the resin adhesive. These different structures can provide mutual restraint during thermal expansion, thereby reducing the overall coefficient of thermal expansion of the material, preventing a decrease in the coefficient of friction after expansion, and enabling it to maintain structural stability at high temperatures, thus exhibiting low expansion performance. At the same time, the active end groups (such as -COOH) of the nitrile rubber undergo a grafting reaction with the hydroxymethyl groups of the phenolic resin. This chemical reaction helps to improve the compatibility and bonding force between the two, so that the resin adhesive retains its original advantages while improving wear resistance and mechanical strength. Based on this, the mass ratio of solid solute in the new phenolic resin, solid solute in the epoxy resin, nitrile rubber, and solvent is (25~45):(2~10):(2~10):(40~60). It should be understood that the proportion of nitrile rubber should not be too high. While this improves abrasion resistance (low wear rate), it also results in higher density, leading to poor air permeability and hindering the penetration of spindle oil. Simultaneously, the amount of epoxy resin used must also be controlled within the aforementioned range. Low amounts of epoxy resin are suitable for applications requiring high abrasion resistance, such as motorcycles and agricultural machinery, while high amounts result in a softer substrate, making them suitable for passenger vehicles. Therefore, resin adhesives prepared using components with the aforementioned proportions improve abrasion resistance while exhibiting good wettability, making them more suitable for the gearbox industry.

[0020] As can be seen from the above, the friction material composition provided in this disclosure is prepared by using a resin binder and a papermaking base paper. The resin binder includes a new phenolic resin, an epoxy resin, a nitrile rubber, and a solvent. Since the new phenolic resin is in a liquid state at a temperature of 25°C, the liquid state of the new phenolic resin is beneficial to improving the wettability of the resin in the substrate, making the papermaking base paper and the resin interface tightly bonded, and giving the substrate good shear strength and toughness.

[0021] By selecting epoxy resins that meet the above-mentioned mass ratio requirements to modify the new phenolic resin, the hydroxymethyl groups in the new phenolic resin react chemically with the hydroxyl and epoxy groups in the epoxy resin, and the phenolic hydroxyl groups in the phenolic resin react chemically with the epoxy groups in the epoxy resin. Finally, they crosslink into a complex and stable three-dimensional structure, giving the mixture the excellent adhesion and toughness of epoxy resin and the excellent heat resistance of new phenolic resin. At the same time, since the epoxy resin molecular chain contains ether bonds and side hydroxyl groups, these functional groups can promote the wetting and bonding force to polar substrates and fillers, thus improving its wettability.

[0022] By selecting nitrile rubber that meets the above-mentioned mass ratio requirements to modify the new phenolic resin, the nitrile rubber molecular backbone has many cyano groups as side groups. The cyano groups have high reactivity and can be hydrolyzed into amide or carboxyl groups under acidic or alkaline conditions. These active groups can form hydrogen bonds with the hydrogen elements in the new phenolic resin molecules, improving the compatibility and bonding force between the phenolic resin and nitrile rubber, and also increasing the strength and density of the mixture, thus enhancing the substrate's resistance to friction and wear. Furthermore, the flowability of the new phenolic resin modified with epoxy resin and nitrile rubber is improved, further enhancing its wetting ability.

[0023] When the above-mentioned resin binder is used to prepare friction materials, the prepared friction materials can maintain the stability of their structure at high temperatures, have low expansion performance, good toughness, and high mechanical strength.

[0024] As one possible implementation, the above-mentioned friction material composition further includes an alcohol solvent, with the mass ratio of resin binder to alcohol solvent being (20-40):(70-90). The friction material is prepared by diluting the resin binder with an alcohol solvent to control the solid content of the resin binder and the amount of resin coating, thereby ensuring that the prepared friction material has good shear strength, wear resistance, and wettability.

[0025] As one possible implementation, the solid content of the aforementioned resin binder is 10% to 20%, for example, it can be 10%, 15%, or 20%, etc., and is not limited to this. Too low a solid content in the resin binder will reduce the shear strength of the paper base, resulting in poor wear resistance and low friction strength, while too high a solid content will lead to low porosity and poor air permeability of the paper base. Therefore, friction materials prepared using resin binders that meet the above-mentioned solid content requirements have better wettability. If a multilayer friction material composition (substrate) is hot-pressed to form a friction material (composite substrate), the interlaminar shear strength of the composite substrate is better, and delamination can be avoided. At the same time, it avoids the resin from being distributed in flake or block form in the base paper, thereby preventing pore blockage to a certain extent, and greatly improving the porosity and air permeability of the substrate. On the other hand, the finished friction material after hot-pressing using a substrate that meets the above requirements has better toughness, better compression resilience, and better heat resistance.

[0026] As one possible implementation, the solvent is an alcohol solvent or water, and the alcohol solvent includes one or more of methanol, ethanol, and isopropanol. Using an alcohol solvent or water as a solvent allows for uniform mixing of the various components of the resin adhesive, improving the overall performance of the resin adhesive. For example, the alcohol solvent can be methanol, ethanol, isopropanol, methanol and ethanol, etc., and is not limited to these.

[0027] As one possible implementation, the aforementioned novel phenolic resin includes phenol and aryl ethers. The novel phenolic resin prepared by the condensation reaction of phenol and aryl ethers is liquid at room temperature. The liquid state of the novel phenolic resin exhibits higher wettability in the substrate, resulting in a tighter bond between the fiber filler and the resin interface, thereby improving the shear strength and toughness of the substrate.

[0028] This disclosure also provides a method for preparing a friction material, which is obtained by hot pressing the above-mentioned friction material composition.

[0029] Compared with the prior art, the beneficial effects of the friction material preparation method provided in this disclosure are the same as the beneficial effects of the friction material composition described in the above technical solution, and will not be repeated here.

[0030] In some alternative embodiments, the shear strength of the aforementioned friction material is 8.5 MPa to 9.3 MPa, the elongation at break of the friction material composition is 6.2% to 8.5%, the dynamic friction coefficient of the friction material composition is 0.16 to 0.19, the static friction coefficient of the friction material composition is 0.18 to 0.22, and the wear rate of the friction material composition is 3.5 × 10⁻⁶. -5 cm 3 / J~3.8*10 - 5 cm 3 The thermal expansion dimensional change rate of the friction material composition is 0.62% to 0.68%. Therefore, the friction material prepared through the exemplary embodiments of this disclosure exhibits superior mechanical properties, friction resistance, and thermal expansion properties.

[0031] For example, the shear strength of the above-mentioned friction material can be 8.5 MPa, 9.2 MPa, or 9.3 MPa, etc., and is not limited thereto; the elongation at break of the friction material composition can be 6.2%, 7.5%, or 8.5%, etc., and is not limited thereto; the dynamic friction coefficient of the friction material composition can be 0.16, 0.17, or 0.19, etc., and is not limited thereto; the static friction coefficient of the friction material composition can be 0.18, 0.20, or 0.22, etc., and is not limited thereto; the wear rate of the friction material composition can be 3.5*10 -5 cm 3 / J、3.7*10 -5 cm 3 / J or 3.8*10 -5 cm 3 The coefficients of friction material composition may be 0.62%, 0.67%, or 0.68%, etc., and are not limited to these.

[0032] In some alternative methods, Figure 1A flowchart illustrating a method for preparing a friction material according to an exemplary embodiment of this disclosure is shown. Figure 1 As shown, the preparation method of the above-mentioned friction material includes:

[0033] Step 110: Mix the new phenolic resin, epoxy resin, nitrile rubber, and solvent evenly to obtain a resin binder. The new phenolic resin can be prepared by a condensation reaction of phenol and aryl alkyl ethers under the action of a catalyst. The catalyst used is an acidic catalyst, which may include one or more of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, and p-toluenesulfonic acid. For example, the acidic catalyst can be hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, p-toluenesulfonic acid, or a mixture of hydrochloric acid and p-toluenesulfonic acid, and is not limited thereto. From an environmental perspective, the solvent used can be water. Mix the prepared new phenolic resin, epoxy resin, nitrile rubber, and solvent according to the above proportions and stir evenly to obtain the resin binder.

[0034] Step 120: Immerse the paper base in the resin binder to obtain the coated substrate. Specifically, when the friction material composition also includes an alcohol solvent, immersing the paper base in the resin binder to obtain the coated substrate includes: first mixing the resin binder and solvent evenly to obtain a coating resin solution, and then immersing the paper base in the coating resin solution to obtain the coated substrate.

[0035] For example, the above-mentioned resin binder can be diluted with an alcohol solvent and stirred evenly before use. Using a coating machine, the evenly stirred resin binder is first poured into an impregnation tank, and then the base paper is impregnated with the resin binder. After the base paper has been saturated with the resin binder in one go, it is removed and excess resin binder is drained off to obtain the coated substrate.

[0036] Step 130: Curing the coated substrate to obtain the friction material. Specifically, the coated substrate can be pre-cured under the first reaction conditions to obtain a pre-cured substrate; then, the pre-cured substrate can be cured under the second reaction conditions to obtain the friction material. The first reaction conditions include a drying temperature of 60℃~100℃ and a drying time of 5min~20min; the second reaction conditions include a heating temperature of 150℃~250℃ and a holding time of 5min~30min; and a hot pressing pressure of 1MPa~5MPa.

[0037] For example, the coated substrate can first be air-dried for a period of time to remove most of the solvent and avoid dangerous accidents, and then placed in an oven for low-temperature drying to obtain a pre-cured substrate. The drying temperature is 60℃~100℃, and the drying time is 5min~20min. For example, the drying temperature can be 60℃, 75℃, or 100℃, etc., and is not limited to these; the drying time can be 5min, 15min, or 20min, etc., and is not limited to these. Then, the pre-cured substrate is placed in a flat vulcanizing machine for curing and molding to obtain a friction material. The heating temperature is 150℃~250℃, the holding time is 5min~30min, and the hot-pressing pressure is 1MPa~5MPa. For example, the heating temperature can be 150℃, 220℃, or 250℃, etc., and is not limited to these; the holding time can be 5min, 15min, or 30min, etc., and is not limited to these; the hot-pressing pressure can be 1MPa, 2MPa, or 5MPa, etc., and is not limited to these.

[0038] This disclosure also provides an application of a friction material composition in a gearbox.

[0039] Compared with the prior art, the beneficial effects of the friction material composition provided in this disclosure in the application of the gearbox are the same as the beneficial effects of the friction material composition described in the above-mentioned technical solutions, and will not be repeated here.

[0040] The present disclosure is further illustrated below by way of embodiments, but these embodiments are not intended to limit the scope of the present disclosure. Experimental methods not specifically described in the following embodiments are performed according to conventional methods and conditions, or as selected in accordance with the product instructions.

[0041] Example 1

[0042] The acidic catalyst used in this embodiment is phosphoric acid, and the alcohol solvent used is methanol.

[0043] Step 1: Preparation of resin adhesive

[0044] First, a new phenolic resin is prepared by condensation reaction of phenol and aryl ether under the catalysis of phosphoric acid, wherein the amount of phosphoric acid is 6% by mass. Then, the new phenolic resin, epoxy resin, nitrile rubber and methanol solvent are weighed and mixed according to the mass ratio of solid solute in the new phenolic resin, solid solute in the epoxy resin, nitrile rubber and solvent of 36:6:6:46, and stirred evenly at medium and high speed for later use.

[0045] Step 2: Impregnating and coating the base paper with resin solution

[0046] The resin binder prepared in step 1 and methanol solvent are mixed evenly to obtain a coating resin solution. Then, using a coating machine, the evenly stirred coating resin solution is first poured into an impregnation tank, and then the base paper is impregnated with the resin solution. After the base paper has been saturated with the resin solution in one pass, it is removed, and excess resin solution is drained off to obtain the coated substrate. The mass ratio of resin binder to methanol solvent is 32:68, and the solid content of the coating resin solution is 16%.

[0047] Step 3: Preparation of pre-cured substrate

[0048] The coated substrate prepared in step 2 was first air-dried for 15 minutes to remove most of the solvent, and then placed in an oven for low-temperature drying to obtain a pre-cured substrate. The drying temperature was 80℃ and the drying time was 10 minutes.

[0049] Step 4: Preparation of friction materials

[0050] The pre-cured substrate prepared in step 3 was placed in a flat vulcanizing machine for curing and molding to obtain the friction material. The heating temperature was 200℃, the holding time was 10 min, and the hot-pressing pressure was 3 MPa. The performance parameters of the friction material prepared in this embodiment are shown in Table 1.

[0051] Example 2

[0052] The acidic catalyst used in this embodiment is hydrochloric acid, and the alcohol solvent used is ethanol.

[0053] Step 1: Preparation of resin adhesive

[0054] First, a new phenolic resin is prepared by condensation reaction of phenol and aryl ether under the catalysis of hydrochloric acid, wherein the amount of hydrochloric acid is 5% by mass. Then, the new phenolic resin, epoxy resin, nitrile rubber and ethanol solvent are weighed and mixed according to the mass ratio of solid solute in the new phenolic resin, solid solute in the epoxy resin, nitrile rubber and solvent of 45:2:10:60, and stirred at medium and high speed until uniform for later use.

[0055] Step 2: Impregnating and coating the base paper with resin solution

[0056] The resin binder prepared in step 1 and the ethanol solvent are mixed evenly to obtain a coating resin solution. Then, using a coating machine, the evenly stirred coating resin solution is first poured into an impregnation tank, and then the base paper is impregnated with the resin solution. After the base paper has been saturated with the resin solution in one pass, it is removed, and excess resin solution is drained off to obtain the coated substrate. The mass ratio of resin binder to ethanol solvent is 20:70, and the solid content of the coating resin solution is 10%.

[0057] Step 3: Preparation of pre-cured substrate

[0058] The coated substrate prepared in step 2 was first air-dried for 15 minutes to remove most of the solvent, and then placed in an oven for low-temperature drying to obtain a pre-cured substrate. The drying temperature was 60℃ and the drying time was 5 minutes.

[0059] Step 4: Preparation of friction materials

[0060] The pre-cured substrate prepared in step 3 was placed in a flat vulcanizing machine for curing and molding to obtain the friction material. The heating temperature was 250℃, the holding time was 30 min, and the hot-pressing pressure was 5 MPa. The performance parameters of the friction material prepared in this embodiment are shown in Table 1.

[0061] Example 3

[0062] The acidic catalyst used in this embodiment is oxalic acid, and the alcohol solvent used is isopropanol.

[0063] Step 1: Preparation of resin adhesive

[0064] First, a new phenolic resin is prepared by condensation reaction of phenol and aryl ether under the catalysis of oxalic acid, wherein the amount of oxalic acid is 8% by mass. Then, the new phenolic resin, epoxy resin, nitrile rubber and isopropanol solvent are weighed and mixed according to the mass ratio of solid solute in the new phenolic resin, solid solute in the epoxy resin, nitrile rubber and solvent of 25:10:2:40, and stirred evenly at medium and high speed for later use.

[0065] Step 2: Impregnating and coating the base paper with resin solution

[0066] The resin binder prepared in step 1 and isopropanol solvent are mixed evenly to obtain a coating resin solution. Then, using a coating machine, the evenly stirred coating resin solution is first poured into an impregnation tank, and then the base paper is impregnated with the resin solution. After the base paper has been saturated with the resin solution in one pass, it is removed, and excess resin solution is drained off to obtain the coated substrate. The mass ratio of resin binder to alcohol solvent is 40:90, and the solid content of the coating resin solution is 20%.

[0067] Step 3: Preparation of pre-cured substrate

[0068] The coated substrate prepared in step 2 was first air-dried for 15 minutes to remove most of the solvent, and then placed in an oven for low-temperature drying to obtain a pre-cured substrate. The drying temperature was 100℃ and the drying time was 20 minutes.

[0069] Step 4: Preparation of friction materials

[0070] The pre-cured substrate prepared in step 3 was placed in a flat vulcanizing machine for curing and molding to obtain the friction material. The heating temperature was 250℃, the holding time was 5 min, and the hot-pressing pressure was 1 MPa. The performance parameters of the friction material prepared in this embodiment are shown in Table 1.

[0071] Comparative Example 1

[0072] The acidic catalyst used in this comparative example is phosphoric acid, and the alcohol solvent used is methanol.

[0073] Step 1: Preparation of resin adhesive

[0074] First, a new phenolic resin was prepared by condensation reaction of phenol and aryl ether under the catalysis of phosphoric acid, wherein the amount of phosphoric acid used was 6 parts by mass. Then, the new phenolic resin was weighed and mixed with methanol solvent, and stirred at medium to high speed until homogeneous for later use. The amount of solid solute in the new phenolic resin was 36 parts by mass, and the amount of methanol solvent was 46 parts by mass.

[0075] Steps 2 to 4 are the same as in Example 1, and the performance parameters of the prepared friction material are shown in Table 1.

[0076] The test methods for the properties of friction materials disclosed herein are as follows:

[0077] Thickness: The thickness of the friction material under no pressure was measured using a thickness gauge. Unit: mm.

[0078] Air permeability: The air permeability of the friction material was tested using a fabric air permeability tester. The unit is L / (m·s).

[0079] Shear strength: The shear strength of the friction material was tested using a universal testing machine. The unit is MPa.

[0080] Elongation at break: The elongation at break of the friction material was tested using a universal testing machine. The unit is %.

[0081] Friction coefficient: The friction performance was tested in accordance with GB / T35472.6, including the midpoint dynamic friction coefficient and the static friction coefficient, without units.

[0082] Wear rate: The ratio of the volume of the sample being worn to the frictional work, i.e., the volume of the sample worn per unit frictional work, unit: cm. 3 / J.

[0083] Dimensional expansion rate of thermal expansion: The sample was cut into 5mm*5mm pieces and heated at 10℃ / min using a TMA apparatus (TA Corporation). The thickness expansion rate of the sample was measured from 50℃ to 360℃. Unit: %.

[0084] Table 1 Performance parameters of friction materials

[0085]

[0086] As shown in Table 1, the shear strength and elongation at break of the friction material in this embodiment are better than those in the comparative example. It can be seen that the friction material prepared by using a friction material composition that meets the proportioning and component requirements of this application has better toughness, is less prone to cracking during use, and has a longer service life.

[0087] The friction material of this embodiment has better air permeability than the comparative example, allowing the heat generated during use to dissipate better and preventing performance degradation due to overheating of the friction pads. Furthermore, the excellent air permeability facilitates the circulation and distribution of lubricating oil, reducing wear on the friction material. The vents allow lubricating oil to penetrate the friction material more effectively, reducing wear and energy loss caused by friction.

[0088] The friction material of this embodiment has a better dynamic friction coefficient and a better static friction coefficient than the comparative example. It can be seen that the friction material of this disclosure can generate greater friction during sliding, thereby improving braking ability, making braking faster and more efficient, and helping to prevent clutch slippage, ensuring smoother operation.

[0089] The wear rate of the friction material in this embodiment is lower than that in the comparative example, indicating that the friction material of this disclosure has better braking effect and longer service life.

[0090] The thermal expansion dimensional change rate of the friction material in this embodiment is lower than that in the comparative example. It can be seen that the friction material of this disclosure has low expansion performance in high temperature environment and can maintain the stability of its structure.

[0091] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0092] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A friction material composition, characterized in that, The friction material composition comprises a resin binder, a paper base, and an alcohol solvent, wherein the mass ratio of the resin binder to the alcohol solvent is (20~40):(70~90). The resin binder comprises a new phenolic resin, an epoxy resin, a nitrile rubber, and a solvent. The new phenolic resin is prepared from phenol and an aryl ether. The mass ratio of the solid solute in the new phenolic resin, the solid solute in the epoxy resin, the nitrile rubber, and the solvent is (25~45):(2~10):(2~10):(40~60).

2. The friction material composition according to claim 1, characterized in that, The solid content of the resin adhesive is 10%~20%; and / or, The solvent is an alcohol solvent or water.

3. The friction material composition according to any one of claims 1 or 2, characterized in that, The alcohol solvent includes one or more of methanol, ethanol, and isopropanol.

4. A method for preparing a friction material, characterized in that, The friction material is obtained by hot pressing the friction material composition according to any one of claims 1 to 3.

5. The method for preparing the friction material according to claim 4, characterized in that, The friction material has a shear strength of 8.5 MPa to 9.3 MPa, an elongation at break of 6.2% to 8.5%, a dynamic friction coefficient of 0.16 to 0.19, a static friction coefficient of 0.18 to 0.22, and a wear rate of 3.5 × 10⁻⁶. -5 cm 3 / J~3.8×10 -5 cm 3 / J, the thermal expansion dimensional change rate of the friction material composition is 0.62%~0.68%.

6. The method for preparing the friction material according to claim 4, characterized in that, The method for preparing the friction material includes: A resin binder is obtained by uniformly mixing phenolic resin, epoxy resin, nitrile rubber and solvent. The resin binder and the solvent are mixed evenly to obtain a coating resin solution; The paper base is immersed in the coating resin solution to obtain a coated substrate; The coated substrate is cured to obtain a friction material.

7. The method for preparing the friction material according to claim 6, characterized in that, The step of curing the coated substrate to obtain a friction material includes: Under the first reaction conditions, the coated substrate is subjected to a pre-curing treatment to obtain a pre-cured substrate; Under the second reaction conditions, the pre-cured substrate is cured to obtain a friction material. The first reaction conditions include a drying temperature of 60℃~100℃ and a drying time of 5min~20min. The second reaction conditions include a heating temperature of 150℃~250℃ and a holding time of 5min~30min. The hot pressing pressure is 1MPa~5MPa.

8. The use of a friction material composition according to any one of claims 1-3 in a gearbox.

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