Friction material composition used for preparing brake pad, and preparation method therefor

Abstract

The present invention relates to the technical field of friction materials, and particularly relates to a friction material composition used for preparing a brake pad, and a preparation method therefor. The friction material composition specifically comprises the following components in parts by mass: 8-12 parts of a matrix phenolic resin, 2-6 parts of a reinforcing component, 4-8 parts of a sepiolite powder, 15-20 parts of a metal oxide, 10-15 parts of calcium carbonate, 6-10 parts of flake graphite, 1-2 parts of zinc stearate, and 1-2 parts of a friction powder. In the friction material composition used for preparing a brake pad and a preparation method therefor, the reinforcing component provided can intensively compensate for the problem of thermal fade caused by using the matrix phenolic resin as a single binder, thereby ameliorating the problem of a reduced friction coefficient caused by thermal fade, and facilitating the further improvement and maintenance of the stability of the friction coefficient at high temperatures.

Description

A friction material composition for preparing brake pads and a preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of friction materials, in particular to a friction material composition for preparing brake pads and a preparation method thereof. BACKGROUND

[0002] Friction material is an important functional material, and the quality of each component composition of the friction material will affect the friction performance; and the main binder of the organic friction material is currently phenolic resin and its modified products

[0003] However, the phenolic resin as the binder of the friction material has the following problems in use: obvious thermal recession phenomenon occurs under high temperature braking, which can cause a significant reduction in the friction coefficient; the thermal recession phenomenon is currently improved by adding physical fillers or modification treatment, but the effect is not good; therefore, it is considered to develop a component that can enhance the performance of the phenolic resin-based friction material, so that the overall friction material composition has good high-temperature resistance and maintains a good friction coefficient; in view of this, we propose a friction material composition for preparing brake pads and a preparation method thereof. SUMMARY

[0004] The purpose of the present application is to solve the problems mentioned in the background art, and to provide a friction material composition for preparing brake pads and a preparation method thereof.

[0005] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0006] A friction material composition for preparing brake pads, comprising a base phenolic resin as a binder, and the mass fraction of each component of the friction material composition is specifically:

[0007] Base phenolic resin: 8-12 parts;

[0008] Reinforcing component: 2-6 parts;

[0009] Meerschaum powder: 4-8 parts;

[0010] Metal oxide: 15-20 parts;

[0011] Calcium carbonate: 10-15 parts;

[0012] Flake graphite: 6-10 parts;

[0013] Zinc stearate: 1-2 parts;

[0014] Friction powder: 1-2 parts.

[0015] Preferably, the reinforcing component comprises polyether ether ketone resin, polyurethane elastomer in a mass ratio of 0.5-1:1, and toluene-2,4-diisocyanate accounting for 5-10% of the total mass of polyether ether ketone resin and polyurethane elastomer.

[0016] Preferably, the metal oxide is aluminum oxide, calcium oxide, magnesium oxide, or diiron trioxide.

[0017] Preferably, the metal oxide has a loose density of 3.0-3.5 g / cm 3 , and a moisture content of no more than 3%.

[0018] A preparation method of a friction material composition for preparing brake pads, the preparation method being: preparing the friction material by sequentially using a granulation process and a powder hot-pressing process according to the proportioning of each component; the specific steps being:

[0019] Step one: mixing, mixing other components in a mixing cylinder to obtain mixed powder, except for the base phenolic resin;

[0020] Step two: preliminary granulation, spraying anhydrous ethanol into the mixed powder and stirring to obtain preliminary pellets;

[0021] Step three: refinement, increasing the stirring speed in step two to break the preliminary pellets into uniform pellets;

[0022] Step four: drying, drying at 60-80°C until the water content is 3-6%, sieving, and sieving particles with a particle size of 2-10 mm;

[0023] Step five: coating and granulation, spreading base phenolic resin powder in a disc, pouring the particles in step four into the disc and shaking to coat the surface of the particles with base phenolic resin powder, and naturally drying in a ventilated place;

[0024] Step six: hot-pressing and curing treatment.

[0025] Preferably, the preparation method of the reinforcing component is: mixing polyether ether ketone resin, polyurethane elastomer, and toluene-2,4-diisocyanate in proportion, setting the temperature to 200-320°C, and obtaining a solid product after 2-6 h of reaction, and refining the powder to 38-75 μm to obtain the reinforcing component.

[0026] Preferably, the hot press forming is provided with: 6-12 MPa pressing pressure, 10-15 min pressure holding time, 140-200 DEG C hot press temperature, 130-140 DEG C mold preheating temperature.

[0027] The hot press forming process is provided with 3-5 times of hot pressing 10-15 s and intermittent exhaust process of exhaust 10-15 s before pressure holding.

[0028] Preferably, the solidification treatment specific method is: the material after hot press forming is placed into a heat treatment drying box, and 140-150 DEG C initial heat preservation 1-1.5 h is sequentially applied, the temperature is raised to 160-170 DEG C, heat preservation is 2-4 h, the temperature is raised to 180-200 DEG C, heat preservation is 5-8 h, and the material is taken out after natural furnace cooling to room temperature.

[0029] Preferably, the temperature rising rate of the solidification treatment is: the temperature is raised to 100-120 DEG C at 2-3 DEG C / min, and the temperature rising rate of the subsequent temperature rising stage is set to 0.25-0.75 DEG C / min.

[0030] Compared with the prior art, the beneficial effects of the present application are:

[0031] The friction material composition for preparing the brake pad and the preparation method thereof can strengthen and compensate the heat recession problem caused by the phenolic resin as a single binder, reduce the problem of reduced friction coefficient caused by heat recession, and be beneficial to further improve and maintain the high-temperature stability of the friction coefficient. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. The embodiments in the present application and the features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0033] The above technical solutions will be described in detail by the following embodiments: EMBODIMENT

[0034] A friction material composition for preparing a brake pad, comprising a base phenolic resin as a binder, and the mass fraction of each component of the friction material composition is specifically:

[0035] The base phenolic resin 2123-1T is 10 parts.

[0036] The reinforcing component is 5.5 parts.

[0037] Sepiolite powder: 7 parts;

[0038] Alumina powder: 20 parts;

[0039] QT-3 calcium carbonate: 10 parts;

[0040] Flaky graphite-195: 8 parts;

[0041] Zinc stearate: 1 part;

[0042] Friction powder: 1 part.

[0043] It should be noted that the reinforcing component in this embodiment specifically includes 2.5 parts of polyether ether ketone resin, 2.5 parts of polyurethane elastomer, and 0.5 parts of toluene-2,4-diisocyanate; in this embodiment, the reinforcing component is prepared in advance and then mixed as a composition component to prepare the friction material; the preparation method of the reinforcing component is: mixing the polyether ether ketone resin, the polyurethane elastomer, and the toluene-2,4-diisocyanate, setting the temperature to 280°C, and obtaining a solid product after 6h of reaction, and then refining, sieving, and taking the 38-75μm powder as the reinforcing component for standby.

[0044] It is worth explaining that this part of the reinforcing component plays an important performance supplement role, in which the polyurethane elastomer contains isocyanate groups, and the polyether ether ketone resin contains hydroxyl groups that can crosslink with isocyanate groups, both of which can be crosslinked under heating conditions, and the toluene-2,4-diisocyanate selected in this embodiment can not only act as a curing agent to improve the molding quality, but also further provide isocyanate groups to play a reinforcing supplement role, so that a crosslinked structure is formed among the three; the polyether ether ketone resin and the polyurethane elastomer themselves have good heat resistance and mechanical properties, and the reason why the reinforcing component raw materials are not directly mixed and granulated in this embodiment is that, compared with the direct mixing of single raw materials, a more stable and performance-combined molecular structure can be obtained after crosslinking, which can play a reinforcing role in the performance of the phenolic resin matrix.

[0045] Specifically, in this embodiment, the base phenolic resin is purchased from Hebei Zetian Chemical Co., Ltd. 2123-1T brand phenolic resin product, in which the free phenol is less than or equal to 2.5%, and the fineness is 200 mesh; the polyether ether ketone resin is purchased from Suzhou Gutai New Material Co., Ltd.; the polyurethane elastomer is purchased from Zhejiang Huafeng Thermoplastic Polyurethane Co., Ltd.; the sepiolite powder with a specific gravity of 2-2.5 g / cm3 is purchased from Shijiazhuang Leisheng Mine Product Co., Ltd.; the metal oxide aluminum oxide powder is purchased from Zhengzhou Xinli Wear-resistant Material Co., Ltd. 4000# specification, 3.2 g / cm3 product; the calcium carbonate powder is purchased from Zhejiang Qintang Calcium Co., Ltd. QT-3 type; the flaky graphite is purchased from China Graphite Group Co., Ltd. 195 type; the zinc stearate is purchased from Liyang Qiangsheng Chemical Co., Ltd.; and the friction powder is purchased from Huadai Science and Technology (Beijing) Co., Ltd.

[0046] The preparation method of the friction material composition for preparing the brake pad in this embodiment is as follows: the friction material is prepared by using the granulation process and the powder hot-pressing process in sequence according to the proportion of each component; and the specific steps are as follows:

[0047] Step one: mixing, except for the base phenolic resin, other components are mixed in the mixing cylinder to obtain mixed powder;

[0048] Step two: preliminary granulation, 30% of the total mass of the powder is sprayed with anhydrous ethanol on the mixed powder, and the mixture is stirred uniformly to obtain preliminary pellets;

[0049] Step three: refinement, the preliminary pellets are broken into uniform pellets;

[0050] Step four: drying, drying at 80°C until the water content is 5%, sieving, and sieving the particles with a particle size of 2-10 mm;

[0051] Step five: coating granulation, the base phenolic resin powder is laid in a disc, the particles of step four are poured into the disc and shaken to coat the surface of the particles with the base phenolic resin powder, and the disc is naturally dried in a ventilated place;

[0052] Step six: hot-pressing, the material of step five is placed in a hot-pressing mold, the pressing pressure is set to 8 MPa, the mold preheating temperature is set to 140°C, when the temperature rises to 180°C, the intermittent exhaust process of 3 times of hot-pressing for 10 s and exhaust for 10 s is repeated, and then the hot-pressing temperature is set to 180°C for 10 min of pressure maintaining;

[0053] Step seven: curing treatment, the material hot-pressed in step six is placed in a JF980D type heat treatment drying oven, the temperature is controlled to rise from room temperature to 120°C at a rate of 2-3°C / min, the temperature is raised to 150°C at a rate of 0.5°C / min, the initial temperature is maintained for 1 h, the temperature is continuously raised to 160°C at a rate of 0.5°C / min, the temperature is maintained for 3 h, the temperature is raised to 180°C at a rate of 0.5°C / min, the temperature is maintained for 6 h, and the material is taken out after the oven is naturally cooled to room temperature to obtain the friction material composition.

[0054] It should be explained that the exhaust process is applied in the hot pressing process in the embodiment, which aims to exhaust the gap gas between materials, residual volatile gas in the resin-based material and the like in the hot pressing temperature rising process, so as to avoid that the gas cannot be exhausted in the hot pressing process and affects the molding quality.

[0055] The purpose of the curing treatment is to improve the curing degree of the matrix phenolic resin and each component, eliminate the thermal stress inside the material to prevent deformation, and at the same time limit the temperature rising rate, the temperature rising speed should not be too fast, and it is not easy to take out quickly, and quality problems such as sudden cooling deformation or sudden heating fracture need to be prevented. Embodiment

[0056] The difference between the embodiment and embodiment 1 is only that in the embodiment, the mass fraction ratio of polyether ether ketone resin and polyurethane elastomer in the reinforcing component is 0.5:1, 1.25 parts of polyether ether ketone resin and 2.5 parts of polyurethane elastomer are set, and other conditions are consistent.

[0057] Comparative example 1

[0058] The difference between the comparative example and embodiment 1 is only that in the comparative example, the reinforcing component is not prepared separately, but the raw materials of the reinforcing component are directly involved in the mixing of step one, and other conditions are consistent.

[0059] Comparative example 2

[0060] The difference between the comparative example and embodiment 1 is only that in the comparative example, no intermittent exhaust process is provided in the hot pressing process, and other conditions are consistent.

[0061] Comparative example 3

[0062] The difference between the comparative example and embodiment 1 is only that in the comparative example, no curing treatment is applied, and other conditions are consistent.

[0063] Comparative example 4

[0064] The difference between the comparative example and embodiment 1 is only that in the comparative example, no reinforcing component is added, and 15.5 parts of matrix phenolic resin are directly used, and other conditions are consistent.

[0065] According to the above embodiment 1, embodiment 2 and comparative examples 1 to 4, samples are prepared, and the friction coefficient and wear amount are tested, and the specific test method is as follows:

[0066] First, each sample is run-in, heated by a heating tube, controlled at a temperature below 100℃, and tested after the surface of the test piece and the friction disc contact surface are ≥95%;

[0067] (1) Coefficient of friction: MMW-1A universal friction and wear tester is selected, the pressure load is 30N, the rotation speed is 200r / min, the friction time is 10min; the small thrust ring sample is selected 32GrMn steel, the opposite diameter is 28mm, the measurement is 5 times to take the average value, and the test temperature is controlled to be 100-350℃.

[0068] (2) Wear amount: the wear amount is measured by the mass loss of the test block per unit time, the rotation speed of the rotating disc is 330r / min, the wear on the rotating disc is 180min, the wear amount after the test at 100-350℃ is weighed, and the percentage of the wear amount to the original mass is taken.

[0069] The specific data are as follows:

[0070]

[0071] From the data in the above table, it can be seen that the initial friction coefficients of example 1 and example 2 at 100℃ are similar, but as the temperature increases, the friction coefficient attenuation trend is greater than that of example 1, and the content of the reinforcing component will affect the thermal decay performance of the friction material, and the wear rate is slightly increased, and the reinforcing component is reduced, and the wear resistance is affected;

[0072] From the data of comparative example 1 and comparative example 4, if the mixture is directly mixed, the friction coefficient of the material will not be obviously improved compared with using all phenolic resin, that is, the anti-thermal decay ability is not fully exhibited, and the mixture cannot form a crosslinked structure between the reinforcing materials, so that the effective function is not realized, and the friction coefficient and the wear amount are still poor;

[0073] From the data of comparative example 2 and comparative example 3, the friction coefficients are similar, but the wear amount is obviously increased, and the reason is that the preparation method is easy to cause internal pores, cracks or deformation defects in the friction material, and the scrap rate of the finished product is high, so it is necessary to apply the solidification and intermittent exhaust process.

[0074] In summary, the reinforcing component and the preparation method thereof can obviously improve the use performance of the friction material, and example 1 can be preferably selected as the implementation manner.

[0075] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

Claims

1. A friction material composition for brake pads comprising as a binder a matrix phenolic resin, characterized in that: The mass fraction of each component of the friction material composition is specifically as follows: matrix phenolic resin: 8-12 parts; reinforcing component: 2-6 parts; sepiolite powder: 4-8 parts; metal oxide: 15-20 parts; calcium carbonate: 10-15 parts; flake graphite: 6-10 parts; zinc stearate: 1-2 parts; friction powder: 1-2 parts.

2. The friction material composition for making brake pads according to claim 1, wherein: The reinforcing component comprises polyether ether ketone resin, polyurethane elastomer, and tolylene-2,4-diisocyanate, and the mass fraction of the polyether ether ketone resin, the polyurethane elastomer, and the tolylene-2,4-diisocyanate is 0.5-1:1 and 5-10% of the total mass of the polyether ether ketone resin and the polyurethane elastomer.

3. The friction material composition for making brake pads as claimed in claim 2 wherein: The metal oxide is aluminum oxide, calcium oxide, magnesium oxide, or diiron trioxide.

4. The friction material composition for making brake pads according to claim 3, wherein: The metal oxide is provided at a bulk density of 3.0-3.5 g / cm 3 a moisture content of not more than 3%.

5. A method for producing a friction material composition for brake pads, suitable for use in the friction material composition according to any one of claims 1 to 4, characterized in that: The preparation method is as follows: the friction material is prepared by using a granulation process and a powder hot-pressing process in sequence according to the proportioning of each component; and the specific steps are as follows: Step one: mixing, except for the matrix phenolic resin, other components are mixed in a mixing cylinder to obtain mixed powder; Step two: preliminary granulation, anhydrous ethanol is sprayed on the mixed powder, and the mixture is stirred uniformly to obtain preliminary pellets; Step three: refinement, the stirring speed in step two is increased to break the preliminary pellets into uniform pellets; Step four: drying, drying is performed at 60-80℃ until the water content is 3-6%, and the pellets with a particle size of 2-10mm are screened out; Step five: coating and granulation, the matrix phenolic resin powder is laid in a disc, the pellets in step four are poured into the disc and shaken to coat the surface of the pellets with the matrix phenolic resin powder, and the disc is naturally dried in a ventilated place; Step six: hot-pressing and curing treatment.

6. The method of claim 5, wherein the friction material composition for brake pads is prepared by the steps of: The preparation method of the reinforcing component is as follows: the polyether ether ketone resin, the polyurethane elastomer, and the tolylene-2,4-diisocyanate are mixed in proportion, the temperature is set to 200-320℃, and the reaction is performed for 2-6h to obtain a solid product, and the powder with a particle size of 38-75μm is refined to be used as the reinforcing component.

7. The method of claim 5, wherein the friction material composition for brake pads is prepared by the steps of: The hot-pressing is provided with a pressing pressure of 6-12MPa, a pressure maintaining time of 10-15min, a hot-pressing temperature of 140-200℃, and a mold preheating temperature of 130-140℃. ​ During the hot-pressing, an intermittent exhaust process is provided before pressure maintaining, which comprises 3-5 times of hot-pressing for 10-15s and exhaust for 10-15s.

8. The method of claim 5, wherein the friction material composition for brake pads is prepared by the steps of: The curing treatment is specifically performed as follows: the material after hot-pressing is placed in a heat treatment drying box, and the initial temperature is set to 140-150℃ for 1-1.5h, the temperature is then increased to 160-170℃, and the temperature is maintained for 2-4h, then the temperature is increased to 180-200℃, and the temperature is maintained for 5-8h, and the material is taken out after natural furnace cooling to room temperature. ​ 9. The method for preparing the friction material composition for brake pads as described in claim 8, characterized in that: The temperature rising rate of the solidification treatment is: 2-3℃ / min to 100-120℃, and the temperature rising rate of the subsequent temperature rising stage is set to 0.25-0.75℃ / min.

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