A brake pad mixture, a synthetic brake pad and a preparation method and application thereof

Abstract

This application relates to the field of brake friction material technology, specifically disclosing a brake pad compound, a synthetic brake pad, its preparation method, and its application. The brake pad compound provided in this application comprises the following components in parts by weight: 10-13 parts liquid nitrile rubber, 8-12 parts modified phenolic resin, 20-40 parts reinforcing fiber, 8-12 parts calcium hydroxide, 1-3 parts light magnesium oxide, 10-15 parts calcium carbonate whiskers, 2-5 parts calcined alumina, 10-15 parts graphite, 5-10 parts heavy calcium carbonate, 0.8-1.2 parts sulfur, and 0.8-1.2 parts accelerator; the reinforcing fiber comprises steel fiber, aramid fiber, and mineral fiber in a weight ratio of (10-25):1:(5-15). The brake pad compound and the method for preparing the synthetic brake pad provided in this application can produce synthetic brake pads with good frictional stability and small batch-to-batch variations, resulting in high safety and reliability when used in traffic vehicle braking systems.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of brake friction materials, in particular to a brake pad mixture, a synthetic brake pad and a preparation method and application thereof. BACKGROUND

[0002] The brake pad material is a key component of the vehicle braking system, and directly affects the braking performance and service life. With the rapid development of rail transit technology, the brake pad material faces more severe working conditions, and is required to have good wear resistance, heat resistance and braking stability, and also needs to consider factors such as cost and environmental protection. The research and development of high-performance brake pad materials are crucial to improving the reliability and safety of the train braking system.

[0003] The existing brake pad materials mainly include rubber-based composite materials, which are mixed with different components to improve the overall performance of the materials. Common components include various rubbers, reinforcing fibers, fillers and the like. However, the existing brake pad preparation processes on the market often cannot guarantee the uniformity of the materials or the performance of the materials changes easily during the mixing process. For example, dry mixing mixes the mixture under no pressure, and the mixing time is short, but the mixture is fluffy and not uniform; the internal mixer mixes the mixture uniformly under certain speed and pressure conditions, but the mixture generates heat during the process, causing chemical reactions of the organic components in the mixture, resulting in unstable quality of the obtained brake pad products, large differences in friction performance between batches, and affecting the safety and stability of the entire braking system.

[0004] Therefore, it is urgent to develop a new brake pad material and a preparation method to prepare a synthetic brake pad with good internal uniformity, good friction stability and reliability, and small batch-to-batch difference. SUMMARY

[0005] In order to improve the friction stability and reliability of the synthetic brake pad, the application provides a brake pad mixture, a synthetic brake pad and a preparation method and application thereof.

[0006] In a first aspect, the application provides a brake pad mixture, which adopts the following technical scheme:

[0007] A brake pad mixture, comprising the following components by weight: 10-13 parts of liquid nitrile rubber, 8-12 parts of modified phenolic resin, 20-40 parts of reinforcing fiber, 8-12 parts of calcium hydroxide, 1-3 parts of light magnesium oxide, 10-15 parts of calcium carbonate whisker, 2-5 parts of calcined alumina, 10-15 parts of graphite, 5-10 parts of heavy calcium carbonate, 0.8-1.2 parts of sulfur, and 0.8-1.2 parts of accelerator.

[0008] The reinforcing fiber comprises steel fiber, aramid fiber and mineral fiber in a weight ratio of (10-25) : 1 : (5-15).

[0009] The application adopts liquid nitrile rubber, modified phenolic resin and reinforcing fibers to prepare a brake pad mixture. The brake pad prepared from the brake pad mixture has good mechanical properties, excellent heat resistance and wear resistance, and is suitable for various vehicle braking systems, effectively improving braking safety and reliability. Specifically, the application adopts steel fibers, aramid fibers and mineral fibers with a weight ratio of (10-25):1:(5-15) as reinforcing fibers. The mixing uniformity between the reinforcing fibers and the liquid nitrile rubber, modified phenolic resin and fillers is good, which can effectively improve the overall mechanical strength and friction performance of the brake pad mixture, making the friction performance of the brake pad more stable. In addition, the presence of liquid nitrile rubber and modified phenolic resin not only ensures good adhesion of the material and excellent adhesion to the metal substrate, but also effectively improves the dimensional stability of the brake pad under high temperature working conditions. The use of light magnesium oxide, calcium carbonate whiskers and other fillers can optimize the friction coefficient of the material, making it more uniform and stable, thereby significantly reducing noise and vibration during braking and prolonging the service life of the brake pad.

[0010] Optionally, the weight ratio of the steel fibers, aramid fibers and mineral fibers is (15-20):1:(8-12).

[0011] In some embodiments, the weight ratio of the steel fibers, aramid fibers and mineral fibers can be (10-15):1:10, (10-20):1:10, (10-25):1:10, (15-20):1:10, (15-25):1:10, (20-25):1:10, 20:1:(5-8), 20:1:(5-10), 20:1:(5-12), 20:1:(5-15), 20:1:(8-10), 20:1:(8-12), 20:1:(8-15), 20:1:(10-12), 20:1:(10-15) or 20:1:(12-15).

[0012] In a specific embodiment, the weight ratio of the steel fibers, aramid fibers and mineral fibers can also be 10:1:10, 15:1:10, 20:1:10, 25:1:10, 20:1:5, 20:1:8 or 20:1:15.

[0013] Optionally, the diameter of the steel fibers is 0.05±0.01mm, and the aspect ratio is 25-35.

[0014] Optionally, the fineness of the calcined alumina is 2500-3500 mesh, the fineness of the calcium hydroxide is 300-350 mesh, and the fineness of the graphite is 80-120 mesh.

[0015] In a second aspect, the application provides a synthetic brake pad.

[0016] Thirdly, this application provides a method for preparing a synthetic brake pad.

[0017] A method for preparing a synthetic galvanic plate includes the following steps:

[0018] Mixing: First, add reinforcing fibers, calcium hydroxide, light magnesium oxide, calcium carbonate whiskers, calcined alumina, graphite, heavy calcium carbonate, sulfur, and accelerator into the mixing equipment. Adjust the main propeller speed v1 to 140-160 rpm and the high-speed propeller speed V to 1500-1900 rpm, and mix for 3-4 minutes. Then, inject liquid nitrile rubber and modified phenolic resin into the mixer, mix for 3-4 minutes, and obtain the brake pad mixture.

[0019] Pressing: The brake pad mixture is pressed at 80-100℃ and 50-65 bar for 200-360 seconds to produce brake pad preforms;

[0020] Curing: Curing the pre-made brake pads to obtain the synthetic brake pads.

[0021] This application provides a method for preparing synthetic brake pads. By controlling the stirring speed of the main slurry and the high-speed slurry within the above-mentioned range, the mixing uniformity of each raw material can be improved, resulting in small differences in the friction performance between batches of the prepared synthetic brake pads and good product stability.

[0022] In some implementations, the main propeller speed v1 can be 140-150 rpm or 150-160 rpm.

[0023] In one specific implementation, the main propeller speed v1 can also be 140 rpm, 150 rpm, or 160 rpm.

[0024] In some implementations, the high-speed propeller speed V can be 1500-1700 rpm or 1700-1900 rpm.

[0025] In one specific implementation, the high-speed propeller speed V can also be 1500 rpm, 1700 rpm, or 1900 rpm.

[0026] Optionally, the feeding time of the liquid nitrile rubber and modified phenolic resin is controlled within 1 minute.

[0027] Optionally, the curing temperature is 210-220℃ and the time is 6-8h.

[0028] Optionally, after the liquid nitrile rubber and modified phenolic resin are added, the main propeller speed v2 needs to be adjusted to 170-190 r / min.

[0029] In some implementations, the main propeller speed v2 can be 150-170 rpm, 150-180 rpm, 150-190 rpm, 150-220 rpm, 170-180 rpm, 170-190 rpm, 170-220 rpm, 180-190 rpm, 180-220 rpm, or 190-220 rpm.

[0030] In one specific implementation, the main propeller speed v2 can also be 150 rpm, 170 rpm, 180 rpm, 190 rpm or 220 rpm.

[0031] Fourthly, the application of the brake pad mixture, synthetic brake pad, and synthetic brake pad preparation method provided in this application in vehicle braking systems.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. This application uses liquid nitrile rubber, modified phenolic resin, reinforcing fibers and calcium hydroxide as raw materials to prepare synthetic brake pads, and uses steel fibers, aramid fibers and mineral fibers in a weight ratio of (10-25):1:(5-15) as reinforcing fibers. The resulting synthetic brake pads have excellent friction properties and friction stability, and when used in traffic vehicle braking systems, they have good safety and reliability.

[0034] 2. This application further controls the weight ratio of steel fiber, aramid fiber and mineral fiber in the reinforcing fiber within the range of (15-20):1:(8-12), resulting in better wear resistance and smaller friction differences in the obtained synthetic brake pads.

[0035] 3. This application improves the uniformity of mixing by adjusting the main impeller speed and high-speed impeller speed in the preparation method of the synthetic brake pad, thereby improving the quality stability of the synthetic brake pad and solving the problem of inconsistent friction performance between batches of synthetic brake pads in related technologies. Detailed Implementation

[0036] This application provides a brake pad compound comprising the following components in parts by weight: 10-13 parts liquid nitrile rubber, 8-12 parts modified phenolic resin, 20-40 parts reinforcing fiber, 8-12 parts calcium hydroxide, 1-3 parts light magnesium oxide, 10-15 parts calcium carbonate whiskers, 2-5 parts calcined alumina, 10-15 parts graphite, 5-10 parts heavy calcium carbonate, 0.8-1.2 parts sulfur, and 0.8-1.2 parts accelerator; the reinforcing fiber comprises steel fiber, aramid fiber, and mineral fiber in a weight ratio of (10-25):1:(5-15). Further, the weight ratio of the steel fiber, aramid fiber, and mineral fiber is (15-20):1:(8-12).

[0037] The steel fiber has a diameter of 0.05±0.01mm and an aspect ratio of 25-35; the calcined alumina has a fineness of 2500-3500 mesh; the calcium hydroxide has a fineness of 300-350 mesh; and the graphite has a fineness of 80-120 mesh.

[0038] The method for preparing the synthetic gate element provided in this application is characterized by comprising the following steps:

[0039] (1) Mixing: Add reinforcing fiber, calcium hydroxide, light magnesium oxide, calcium carbonate whiskers, calcined alumina, graphite, heavy calcium carbonate, sulfur and accelerator into a vacuum mixer. Adjust the main paddle speed to 140-160 rpm and the high-speed paddle speed to 1500-1900 rpm, and mix for 3-4 minutes. Then, inject liquid nitrile rubber and modified phenolic resin into the mixer through the atomizing pouring port within 1 minute, and increase the main paddle speed to 170-190 r / min. After mixing for 3-4 minutes, obtain the brake pad mixture.

[0040] (2) Pressing: Press the brake pad mixture using a proportional press at 80-100℃ and a pressing pressure of 50-65 bar for 200-360s to produce brake pad preforms.

[0041] (3) Curing: Curing the preform of the brake pad at 210-220℃ for 6-8 hours to obtain the synthetic brake pad.

[0042] In this application, the liquid nitrile rubber is model LNBR-827XE; the modified phenolic resin is model PF2184; the steel fiber has a diameter of 0.05 mm and an aspect ratio of 20; the aramid fiber is model HP100; the mineral fiber is model RB250; the light magnesium oxide is model 93C-BL; the calcium hydroxide has a fineness of 325 mesh; the calcium carbonate whiskers are model NP-M02; the calcined alumina has a fineness of 3000 mesh and was purchased from Hangzhou Xiaoshan Great Wall Aluminum Materials Co., Ltd.; the graphite has a fineness of 100 mesh and was purchased from Qingdao Chenglong Graphite Co., Ltd.; the heavy calcium carbonate has a fineness of 325 mesh and was purchased from Nanyang Fuxiang Calcium Carbonate; the accelerator is model DM; all raw materials, reagents, solvents, etc. used in this application are commercially available.

[0043] The present application will be further described in detail below with reference to the embodiments and performance test results.

[0044] Examples 1-8

[0045] Examples 1-8 each provide a synthetic brake pad.

[0046] The difference in the above embodiments is that the proportions of each component in the reinforcing fiber are as shown in Table 1 below.

[0047] The method for preparing the synthetic thimble provided in Examples 1-8 includes the following steps:

[0048] (1) Mixing: Add reinforcing fiber, calcium hydroxide, light magnesium oxide, calcium carbonate whiskers, calcined alumina, graphite, heavy calcium carbonate, sulfur and accelerator into a vacuum mixer, adjust the main paddle speed v1 to 150 rpm and the high-speed paddle speed V to 1700 rpm, and mix for 3 min; then inject liquid nitrile rubber and modified phenolic resin into the mixer through the atomizing pouring port of the mixer within 1 min, and increase the main paddle speed v2 to 180 r / min, and mix for 3 min to obtain the brake pad mixture.

[0049] (2) Pressing: The brake pad mixture is pressed using a proportional press at 90°C and 60 bar for 240 seconds to produce brake pad preforms.

[0050] (3) Curing: The preform of the brake pad is cured at 220℃ for 8 hours to obtain the synthetic brake pad.

[0051] Table 1 shows the weight ratio of each component of the reinforcing fiber in the synthetic brake pads provided in Examples 1-8.

[0052] Example Weight ratio of steel fibers, aramid fibers and mineral fibers 1 10：1：10 2 15：1：10 3 20：1：10 4 25：1：10 5 20：1：5 6 20：1：8 7 20：1：12 8 20：1：15

[0053] Examples 9-16

[0054] Examples 9-16 each provide a synthetic brake pad.

[0055] The difference between the above embodiments and Embodiment 3 is that the rotation speed in the mixing step is as shown in Table 2 below.

[0056] Table 2 shows the rotation speed during the mixing step of the preparation methods in Examples 3 and 9-16.

[0057]

[0058] Comparative Example 1

[0059] Comparative Example 1 provides a synthetic brake pad.

[0060] The difference between the above comparative example and Example 3 is that the reinforcing fibers include steel fibers, aramid fibers and mineral fibers in a weight ratio of 1:1:1.

[0061] Comparative Example 2

[0062] Comparative Example 2 provides a synthetic brake pad.

[0063] The difference between the above comparative example and Example 3 is that the reinforcing fibers include steel fibers, aramid fibers and mineral fibers in a weight ratio of 5:1:5.

[0064] Comparative Example 3

[0065] Comparative Example 3 provides a synthetic brake pad.

[0066] The difference between the above comparative example and Example 3 is that the main propeller speed v1 is 100 rpm and the high-speed propeller speed V is 1300 rpm.

[0067] Comparative Example 4

[0068] Comparative Example 4 provides a synthetic brake pad.

[0069] The difference between Comparative Example 4 and Example 3 lies in the method of preparing the synthetic brake pad.

[0070] The method for preparing the synthetic thimble provided in Comparative Example 4 includes the following steps:

[0071] 1. Mixing: Liquid nitrile rubber, modified phenolic resin, reinforcing fiber, calcium hydroxide, light magnesium oxide, calcium carbonate whiskers, calcined alumina, graphite, heavy calcium carbonate, sulfur and accelerator are put into a vacuum mixer. The main paddle speed v1 is adjusted to 150 rpm and the high-speed paddle speed V is adjusted to 1700 rpm. Mix for 5 minutes to obtain the brake pad mixture.

[0072] (2) Pressing: The brake pad mixture is pressed using a proportional press at 90°C and 60 bar for 240 seconds to produce brake pad preforms.

[0073] (3) Curing: The preform of the brake pad is cured at 220℃ for 8 hours to obtain the synthetic brake pad.

[0074] Performance testing

[0075] The frictional stability of the synthetic brake pads prepared in Examples 1-16 and Comparative Examples 1-4 was tested, and the results are shown in Table 3 below: Frictional stability experiment: The synthetic brake pads were subjected to emergency braking at 120 km / h, and the friction coefficient of the synthetic brake pads was tested; the friction coefficients of 5 batches were tested in parallel, and the relative standard deviation (RSD) of the 5 sets of data was calculated.

[0076] Note: When performing emergency braking at 120 km / h, the friction coefficient of the brake pads should be 0.310-0.406.

[0077] The smaller the relative standard deviation (RSD) value, the smaller the batch-to-batch variation of the synthesized brake pads and the better the frictional stability.

[0078] Table 3. Test results of the frictional stability of the synthetic brake pads in Examples 1-16 and Comparative Examples 1-4.

[0079]

[0080]

[0081] According to the test results in Table 3, the average friction coefficient of the synthetic brake pads obtained in Examples 1-16 of this application is 0.354-0.360, and the RSD value of the friction coefficient of the 5 batches of products is 0.38-0.69%. This indicates that the brake pad mixture and the preparation method of the synthetic brake pads provided in this application can produce synthetic brake pads with good uniformity and excellent quality stability. When used in vehicle braking systems, these brake pads can meet the requirements for safety and reliability.

[0082] The test results of Examples 1-8 and Comparative Examples 1-2 show that Examples 1-8 used steel fibers, aramid fibers, and mineral fibers in a weight ratio of (10-25):1:(5-15) as reinforcing fibers. The reinforcing fibers showed good uniformity in mixing with the components in the brake pad mixture, resulting in good quality stability of the synthesized brake pads. The average friction coefficient of the synthesized brake pads was 0.354-0.360, and the RSD value of the friction coefficient of the 5 batches of products was 0.39-0.69%. However, when Comparative Examples 1-2 used steel fibers, aramid fibers, and mineral fibers in a weight ratio of 1:1:1 or 5:1:5 as reinforcing fibers, the bonding effect between the reinforcing fibers and the rubber, resin, and fillers was poor, resulting in poor internal uniformity of the synthesized brake pads and poor quality stability. The RSD value of the friction coefficient of the 5 batches of products was as high as 1.81-2.58%. Therefore, it is shown that by using steel fiber, aramid fiber and mineral fiber in a weight ratio of (10-25):1:(5-15) as reinforcing fibers, this application can prepare a synthetic brake pad with good frictional stability.

[0083] Further comparison of Examples 1-8 revealed that the RSD values ​​of the friction coefficients of the five batches of synthetic brake pads obtained in Examples 2-3 and 6-7 were 0.39-0.47% (≤0.5%); while the RSD values ​​of the friction coefficients of the five batches of synthetic brake pads obtained in Examples 1, 4-5, and 8 were 0.52-0.69%. Therefore, it is demonstrated that the synthetic brake pads prepared by further using steel fibers, aramid fibers, and mineral fibers in a weight ratio of (15-20):1:(8-12) as reinforcing fibers in this application exhibit better frictional stability.

[0084] The test results of Examples 3, 9-16, and Comparative Examples 3-4 show that, in Examples 3 and 9-16, by adjusting the order of adding each raw material and controlling the main propeller speed v1 in the mixing process within the range of 140-160 rpm and the high-speed propeller speed V within the range of 1500-1900 rpm, the average friction coefficient of the synthesized brake pads was 0.356-0.360, and the RSD value of the friction coefficient of the 5 batches of products was 0.39-0.78%. In Comparative Example 3, by controlling the main propeller speed v1 in the mixing process within the range of 100 rpm and the high-speed propeller speed V within the range of 1300 rpm, the average friction coefficient of the synthesized brake pads was 0.357, and the RSD value of the friction coefficient of the 5 batches of products was as high as 2.80%. In Comparative Example 4, by directly mixing all raw materials at once, the average friction coefficient of the synthesized brake pads was 0.353, and the RSD value of the friction coefficient of the 5 batches of products was as high as 3.87%. Therefore, this application explains that the order of adding raw materials is adjusted as follows: reinforcing fibers and fillers are added first, followed by liquid nitrile rubber and modified phenolic resin. Furthermore, the main propeller speed v1 during the mixing process is controlled within the range of 140-160 rpm, and the high-speed propeller speed V is controlled within the range of 1500-1900 rpm. This ensures that the materials for the synthesized brake pads are thoroughly and uniformly mixed, thereby significantly improving the quality stability of the synthesized brake pads. Further comparison of the test results of Examples 3 and 13-16 shows that as the main propeller speed v2 increases, the friction coefficient RSD values ​​of the five batches of synthesized brake pads obtained show a trend of first decreasing and then remaining essentially unchanged. Specifically, in Example 13, when both the main propeller speed v1 and v2 are set to 150 rpm, the friction coefficient RSD value of the five batches of synthesized brake pads obtained is 0.78% (>0.5%); while the friction coefficient RSD values ​​of the five batches of synthesized brake pads obtained in Examples 3 and 14-16 are 0.39-0.48% (≤0.5%). Therefore, considering the overall cost, this application further controls the main propeller speed v2 within the range of 170-190 rpm, resulting in better uniformity of the synthesized brake pads, smaller differences in friction performance between batches of the synthesized brake pads, and better product stability.

[0085] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A composite thimble, characterized in that, Made from a mixture of brake pad materials; The brake pad mixture comprises the following components in parts by weight: 10-13 parts liquid nitrile rubber, 8-12 parts modified phenolic resin, 20-40 parts reinforcing fiber, 8-12 parts calcium hydroxide, 1-3 parts light magnesium oxide, 10-15 parts calcium carbonate whiskers, 2-5 parts calcined alumina, 10-15 parts graphite, 5-10 parts heavy calcium carbonate, 0.8-1.2 parts sulfur, and 0.8-1.2 parts accelerator; The reinforcing fibers comprise steel fibers, aramid fibers, and mineral fibers in a weight ratio of (15-20):1:(8-12); The method for preparing the synthetic galvanic plate includes the following steps: Mixing: First, add reinforcing fibers, calcium hydroxide, light magnesium oxide, calcium carbonate whiskers, calcined alumina, graphite, heavy calcium carbonate, sulfur, and accelerator into the mixing equipment. Adjust the main propeller speed v1 to 140-160 rpm and the high-speed propeller speed V to 1500-1900 rpm, and mix for 3-4 minutes. Then, inject liquid nitrile rubber and modified phenolic resin into the mixer, adjust the main propeller speed v2 to 170-190 r / min, and mix for 3-4 minutes to obtain the brake pad mixture. Pressing: The brake pad mixture is pressed at 80-100℃ and 50-65 bar for 200-360 seconds to produce brake pad preforms; Curing: Curing the pre-made brake pads to obtain the synthetic brake pads.

2. The composite brake pad according to claim 1, characterized in that, The steel fiber has a diameter of 0.05±0.01mm and an aspect ratio of 25-35.

3. The composite brake pad according to any one of claims 1-2, characterized in that, The fineness of the calcined alumina is 2500-3500 mesh, the fineness of the calcium hydroxide is 300-350 mesh, and the fineness of the graphite is 80-120 mesh.

4. The composite brake pad according to claim 1, characterized in that, The feeding time of the liquid nitrile rubber and modified phenolic resin is controlled within 1 minute.

5. The composite brake pad according to claim 1, characterized in that, The curing temperature is 210-220℃, and the time is 6-8 hours.

6. The application of a synthetic brake pad as described in any one of claims 1-5 in a vehicle braking system.

Images