Composite binder, friction material, brake pad, preparation method and vehicle

Abstract

The invention discloses a composite binder, a friction material, a brake pad, a preparation method and a vehicle. The composite binder of the present application comprises: an organic binder; an inorganic binder, wherein the inorganic binder comprises phosphate; a curing agent including a metal oxide; the mass ratio of the inorganic binder to the curing agent is 10: (3-7). According to the composite binder, the high-temperature bonding strength of the friction layer can be improved, braking noise is reduced, and the overall braking efficiency of the brake pad is improved.

Description

Technical Field

[0001] This application relates to the field of materials processing technology, specifically to composite binders, friction materials, brake pads and their preparation methods, and vehicles. Background Technology

[0002] Currently, organic binders combined with porous materials are commonly used for the friction layer of brake pads. Specifically, the manufacturing process of brake pads includes: first, mixing organic binders with reinforcing fibers, porous materials, and other fillers in a certain proportion to obtain a mixture; placing the mixture on a steel backing and hot-pressing it through a mold; and then performing heat treatment and other processes to obtain low-noise brake pads.

[0003] However, organic binders (such as phenolic resins) provide good adhesion for reinforcing fibers and other fillers in the friction layer at low and medium temperatures, but the high-temperature conditions during braking may cause the resin to fail, which can lead to braking noise. Summary of the Invention

[0004] This application aims to at least partially solve one of the technical problems in the related art. Therefore, one objective of this application is to provide a composite binder, friction material, brake pads, a preparation method thereon, and a vehicle. The composite binder of this application can improve the high-temperature bonding strength of the friction layer, reduce braking noise, and improve the overall braking performance of the brake pads.

[0005] The first aspect of this application discloses a composite adhesive. According to embodiments of this application, the composite adhesive comprises:

[0006] Organic adhesives;

[0007] Inorganic binders, including phosphates;

[0008] Curing agents, including metal oxides;

[0009] The mass ratio of inorganic binder to curing agent is 10:(3~7).

[0010] The bonding principle of the inorganic phosphate binder in this application is that phosphate ions continuously undergo dehydration condensation reactions during heating, and monomeric phosphate molecules polymerize into linear polyphosphates, which continue to react to form a three-dimensional POP network structure. Under the promotion of a curing agent, the aforementioned phosphate binder can undergo dehydration condensation reactions at relatively low temperatures to form a network porous structure, with the number of pores increasing with increasing temperature. The resulting network porous structure: on the one hand, can tightly bond various powders (including other raw materials in friction materials), improving the bonding strength of the powders at high temperatures, improving the high-temperature resistance of brake pads, and enhancing high-temperature bonding and shear strength; on the other hand, it can increase the specific surface area, improve the transmission path of sound waves, effectively increase the degree of sound wave absorption, and reduce brake pad noise.

[0011] Some organic binders may produce toxic substances during use. For example, most organic phenolic resins contain toxic substances such as phenols and aldehydes, and may also produce toxic gases such as carbon monoxide and sulfur dioxide at high temperatures. This not only pollutes the environment but also harms human health. Furthermore, porous materials suffer from problems such as looseness and low strength, which may cause friction surface material to detach during braking, increasing the incidence of braking noise. In this application embodiment, an inorganic binder, phosphate, is added. Under the promotion of a curing agent, a network porous structure is formed, improving high-temperature bonding performance and reducing noise, thus reducing the amount of organic binder and porous material used. A small amount of organic binder fills the pores of the network structure, synergistically ensuring the overall high-temperature performance of the composite binder. Simultaneously, the porous network structure can replace some of the porous material, reducing noise. Therefore, a small amount of organic binder and porous material can achieve high-temperature resistance and low noise. This also helps reduce the generation of toxic and harmful substances, reduces the occurrence of porous material detachment, and lowers the incidence of braking noise.

[0012] The second aspect of this application discloses a friction material whose raw material composition includes the aforementioned composite binder.

[0013] The friction material provided in this application contains the aforementioned composite binder in its raw material composition and has all the advantages of the aforementioned composite binder. The friction layer formed using this friction material exhibits high high-temperature bonding and shear strength, as well as a low braking noise rate.

[0014] A third aspect of this application discloses a brake pad, including a friction layer, wherein the friction layer is made of the aforementioned friction material.

[0015] In the friction layer of the brake pads provided in this application, the organic and inorganic binders work together to ensure the bonding and shear strength of the brake pads under low and high temperature conditions. At the same time, the porous structure formed by the dehydration and condensation of the inorganic binder and other porous materials play a role in absorbing sound waves and reducing braking noise.

[0016] The fourth aspect of this application discloses a method for preparing brake pads, comprising:

[0017] Using the above-mentioned friction material, the raw materials of the friction material are mixed to obtain a mixture;

[0018] Brake pads are prepared by hot pressing, curing, and heat treatment of the mixed materials.

[0019] This application introduces a non-toxic, high-temperature resistant inorganic binder, which works in conjunction with an organic binder to bond reinforcing fibers, porous materials, and other fillers. The inorganic binder undergoes dehydration and condensation at a certain temperature to generate a three-dimensional network porous structure. The resulting brake pad mixture is then subjected to processes such as hot pressing, curing, and heat treatment to obtain a high-temperature resistant, low-noise brake pad.

[0020] According to the fifth aspect of this application, a vehicle is provided with the above-described brake pads, or with brake pads prepared by the above-described method.

[0021] The vehicle proposed in this application has the aforementioned brake pads, which are resistant to high temperatures and have a low braking noise rate, exhibiting good overall braking performance.

[0022] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0024] Figure 1 A schematic diagram of the raw materials for the phosphate dehydration condensation reaction in an embodiment of this application is shown.

[0025] Figure 2 The image shows a SEM image of the composite adhesive provided in Embodiment 10 of this application after heat treatment. Detailed Implementation

[0026] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0027] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0028] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this application.

[0029] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0030] Currently, organic binders combined with porous materials are commonly used for the friction layer of brake pads. Specifically, the manufacturing process of brake pads includes: first, mixing organic binders with reinforcing fibers, porous materials, and other fillers in a certain proportion to obtain a mixture; placing the mixture on a steel backing and hot-pressing it through a mold; and then performing heat treatment and other processes to obtain low-noise brake pads.

[0031] However, organic binders (such as phenolic resins) provide good adhesion for reinforcing fibers and other fillers in the friction layer at low and medium temperatures, but the high-temperature conditions during braking may cause the resin to fail, which can lead to braking noise.

[0032] Therefore, the first aspect of this application proposes a composite adhesive. According to an embodiment of this application, the composite adhesive includes:

[0033] Organic adhesives;

[0034] Inorganic binders, including phosphates;

[0035] Curing agents, including metal oxides;

[0036] The mass ratio of inorganic binder to curing agent is 10:(3~7).

[0037] In this embodiment, the bonding principle of the inorganic phosphate binder is that phosphate ions continuously undergo dehydration condensation reactions during heating, and monomeric phosphate molecules polymerize into linear polyphosphates, which continue to react to generate a three-dimensional POP network structure. The aforementioned phosphate binder, under the promotion of a curing agent, can undergo dehydration condensation reactions at relatively low temperatures to form a network porous structure, with the number of pores increasing with temperature. The generated network porous structure: on the one hand, can tightly bond various powders (including other raw materials in friction materials), improving the bonding strength of the powders at high temperatures, improving the high-temperature resistance of brake pads, and enhancing high-temperature bonding and shear strength; on the other hand, it can increase the specific surface area, improve the transmission path of sound waves, effectively increase the degree of sound wave absorption, and reduce brake pad noise.

[0038] Some organic binders may produce toxic substances during use. For example, most organic phenolic resins contain toxic substances such as phenols and aldehydes, and may also produce toxic gases such as carbon monoxide and sulfur dioxide at high temperatures. This not only pollutes the environment but also harms human health. Furthermore, porous materials suffer from problems such as looseness and low strength, which may cause friction surface material to detach during braking, increasing the incidence of braking noise. In this application embodiment, an inorganic binder, phosphate, is added. Under the promotion of a curing agent, a network porous structure is formed, improving high-temperature bonding performance and reducing noise, thus reducing the amount of organic binder and porous material used. A small amount of organic binder fills the pores of the network structure, synergistically ensuring the overall high-temperature performance of the composite binder. Simultaneously, the porous network structure can replace some of the porous material, reducing noise. Therefore, a small amount of organic binder and porous material can achieve high-temperature resistance and low noise. This also helps reduce the generation of toxic and harmful substances, reduces the occurrence of porous material detachment, and lowers the incidence of braking noise.

[0039] In addition, the embodiments of this application use metal oxides as curing agents, which are not only suitable for promoting the dehydration and condensation of phosphates at low temperatures to form a porous network structure, but also have the advantages of high hardness, good friction resistance and good thermal stability, and can be used as friction layer materials.

[0040] In this application, phosphates are selected as the inorganic binder. Phosphates are non-toxic, high-temperature resistant, and have low thermal conductivity, which can improve the high-temperature bonding performance of the composite binder. Furthermore, the phosphates used are those prepared by reacting phosphoric acid with metal oxides / hydroxides, which have the advantages of low-temperature curing and high bonding strength.

[0041] The mass ratio of inorganic binder to curing agent is 10:(3~7). In specific examples, the mass ratio of inorganic binder to curing agent is 10:3, 10:3.5, 10:4, 10:4.5, 10:5, 10:5.5, 10:6, 10:6.5, 10:7, etc.

[0042] According to embodiments of this application, the mass ratio of inorganic binder to curing agent is 10:(5-7). Specific examples include mass ratios of 10:5, 10:5.2, 10:5.4, 10:5.6, 10:5.8, 10:6.0, 10:6.2, 10:6.4, 10:6.6, 10:6.8, and 10:7.

[0043] In this embodiment, the mass ratio of inorganic binder to curing agent satisfies the above conditions. On the one hand, this promotes the low-temperature dehydration and condensation of phosphate to form a porous network structure, thereby improving high-temperature bonding performance. On the other hand, the curing agent plays a role in regulating friction. The overall synergistic effect helps to reduce the braking noise rate of the brake pads.

[0044] According to embodiments of this application, the metal oxide includes at least one of zirconium oxide, aluminum oxide, and zinc oxide; and / or, the phosphate includes at least one of aluminum dihydrogen phosphate, zinc dihydrogen phosphate, and calcium dihydrogen phosphate.

[0045] The curing agent used in this application includes at least one of zirconium oxide, alumina, and zinc oxide. These oxides, besides being suitable for promoting the dehydration condensation of phosphates to form a porous network structure at low temperatures, have advantages such as high hardness, good abrasion resistance, and good thermal stability, making them suitable as friction layer materials. In this application embodiment, the metal oxide is at least one of zirconium oxide and alumina, which can promote the dehydration condensation of phosphates to form a porous network structure at low temperatures, while also having better abrasion resistance, facilitating its interaction with inorganic binders to reduce noise.

[0046] In this embodiment, the above-mentioned dihydrogen phosphate is used as an inorganic binder, which has the advantages of being non-toxic, having low thermal conductivity, and strong bonding performance. Moreover, the above-mentioned dihydrogen phosphate has high activity and can be cured at low temperature to form a porous network structure, which is beneficial to improving high-temperature bonding performance and reducing noise.

[0047] According to embodiments of this application, the organic adhesive includes phenolic resin adhesives.

[0048] The phenolic resin adhesive used in this embodiment exhibits excellent low-temperature adhesion and fluidity at lower temperatures. It can fill the cavities in the porous structure resulting from the dehydration and condensation of phosphates, synergistically enhancing the high-temperature adhesion of the composite adhesive with the inorganic components. Furthermore, the phenolic resin adhesive possesses good elasticity, providing a cushioning effect for the friction layer and improving the safety performance of the brake pads.

[0049] According to embodiments of this application, the organic binder includes at least one of unmodified phenolic resin, nitrile-modified phenolic resin, cashew nut shell oil-modified phenolic resin, melamine-modified phenolic resin, molybdenum-modified phenolic resin, and boron-modified phenolic resin; further, the organic binder includes at least one of cashew nut shell oil-modified phenolic resin and / or boron-modified phenolic resin.

[0050] In this embodiment, the organic binder includes at least one of the above-mentioned phenolic resin binders, which is beneficial for obtaining a composite binder with good strong bonding performance. In particular, the use of modified phenolic resin binders, such as at least one of nitrile-modified phenolic resin, cashew nut shell oil-modified phenolic resin, melamine-modified phenolic resin, molybdenum-modified phenolic resin, and boron-modified phenolic resin, has better high-temperature resistance, which is beneficial for further improving the high-temperature bonding strength of the composite binder. As a more preferred embodiment, the organic binder includes at least one of cashew nut shell oil-modified phenolic resin and / or boron-modified phenolic resin.

[0051] According to embodiments of this application, the composite adhesive comprises, by weight, the following:

[0052] Organic binder, 4 to 5 parts;

[0053] Inorganic binder, 10 to 11 parts;

[0054] Hardener, 3 to 7 parts.

[0055] In this embodiment, the organic binder, inorganic binder, and curing agent satisfy the above-mentioned weight ratio, which is beneficial to fully utilize the synergistic effect between the components, improve the overall high-temperature bonding strength and shear force of the friction layer, and reduce the noise generation rate. This embodiment reduces the amount of organic binder, forming a large number of porous network structures, which improves the high-temperature resistance of the friction layer while further reducing the noise generation rate; and the addition of a relatively large amount of curing agent can play a role in regulating friction.

[0056] The second aspect of this application provides a friction material whose raw material composition includes the aforementioned composite binder.

[0057] The friction material provided in this application embodiment contains the above-mentioned composite binder in its raw material composition. It has all the advantages of the above-mentioned composite binder. The friction layer formed by using this friction material exhibits high high-temperature bonding and shear strength, as well as a low braking noise rate.

[0058] According to embodiments of this application, the raw material composition further includes porous materials, reinforcing fibers, and fillers; the mass percentage of the composite binder is 17wt% to 21wt%.

[0059] Porous materials are used to absorb sound waves and reduce noise; reinforcing fibers and fillers are used to improve the high-temperature resistance and friction performance of the friction layer. This application introduces a non-toxic, high-temperature resistant inorganic binder, which works synergistically with an organic binder to bond the reinforcing fibers, porous materials, and other fillers, thereby improving high-temperature bond strength and reducing noise.

[0060] In the embodiments of this application, the mass percentage of the composite binder in the friction material meets the above conditions, which is 17wt% to 21wt%.

[0061] According to the embodiments of this application, the raw material composition of the friction material satisfies any one of the following (1) to (3):

[0062] (1) Porous materials include at least one of expanded graphite, vermiculite and calcium silicate;

[0063] (2) The reinforcing fiber includes at least one of steel fiber, copper fiber, aramid fiber, carbon fiber and glass fiber;

[0064] (3) The filler includes at least one of flake graphite, nitrile rubber and barium sulfate.

[0065] In the embodiments of this application, for any one of the porous material, reinforcing fiber, and filler, those skilled in the art can choose conventional materials used in the field for brake pad friction layers, without limitation. As a specific example, the porous material can be at least one of expanded graphite, vermiculite, and calcium silicate, which is inexpensive and has stable high-temperature performance, and can be used as a porous friction performance regulating material. The reinforcing fiber can be at least one of steel fiber, copper fiber, aramid fiber, carbon fiber, and glass fiber, and the filler can be at least one of flake graphite, nitrile rubber, and barium sulfate.

[0066] According to embodiments of this application, the raw material composition of the friction material, by weight, includes:

[0067] Composite adhesive, 17 to 23 parts;

[0068] Porous material, 10 to 19 parts;

[0069] Reinforcing fibers, 17 to 34 parts;

[0070] Filler, 27 to 54 parts.

[0071] In this embodiment, the composite binder, porous material, reinforcing fiber, and filler meet the above-mentioned weight ratio, which facilitates the overall synergistic effect and improves the high-temperature resistance and low-noise performance of the friction layer. This embodiment reduces the amount of organic binder, improving high-temperature resistance and safety; simultaneously, it reduces the content of reinforcing fiber, increasing the porosity of the resulting friction layer and thus reducing noise; and by replacing part of the porous material, it further avoids excessive powder shedding that could increase braking noise.

[0072] According to embodiments of this application, the raw material composition of the friction material, by weight, includes:

[0073] Cashew shell oil modified phenolic resin, 4 to 5 parts;

[0074] 10 to 11 parts of inorganic binder;

[0075] 3 to 7 parts curing agent;

[0076] 10 to 20 parts steel fiber;

[0077] 5 to 10 parts copper fiber;

[0078] 2 to 4 parts aramid fiber;

[0079] 2 to 4 parts vermiculite;

[0080] 3-5 parts calcium silicate;

[0081] 5 to 10 parts expanded graphite;

[0082] 5 to 10 parts of flake graphite;

[0083] 2 to 4 parts of nitrile rubber;

[0084] Barium sulfate, 20 to 40 parts.

[0085] According to embodiments of this application, the raw material composition of the friction material, by weight, includes:

[0086] Cashew shell oil modified phenolic resin, 4 to 5 parts;

[0087] 10 to 11 parts phosphate;

[0088] 3 to 7 parts of metal oxide;

[0089] 10 to 20 parts steel fiber;

[0090] 5 to 10 parts copper fiber;

[0091] 2 to 4 parts aramid fiber;

[0092] 2 to 4 parts vermiculite;

[0093] 3-5 parts calcium silicate;

[0094] 5 to 10 parts expanded graphite;

[0095] 5 to 10 parts of flake graphite;

[0096] 2 to 4 parts of nitrile rubber;

[0097] Barium sulfate, 20 to 40 parts.

[0098] The specific friction material composition and formulation proposed in the embodiments of this application result in a friction layer that exhibits good high-temperature adhesion and strong shear force, while reducing the occurrence rate of braking noise.

[0099] A third aspect of this application provides a brake pad including a friction layer, wherein the friction layer is made of the aforementioned friction material.

[0100] In the friction layer of the brake pads provided in this application embodiment, the organic and inorganic binders work together to ensure the bonding and shear strength of the brake pads under low and high temperature conditions. At the same time, the porous structure formed by the dehydration condensation of the inorganic binder and other porous materials play a role in absorbing sound waves and reducing braking noise.

[0101] According to an embodiment of this application, the friction layer satisfies at least one of the following:

[0102] (a) The density of the friction layer is 2.6 g / cm³. 3~2.8g / cm 3 ;

[0103] (b) The porosity of the friction layer is 20%–25%;

[0104] (c) The thickness of the friction layer is 8mm to 12mm.

[0105] The composite binder plays a role in binding the brake pad powder. The phosphate in the binder undergoes a dehydration condensation reaction during heating, generating a three-dimensional network porous structure. Therefore, the type and content of the curing agent in the inorganic component, as well as the heat treatment temperature of the brake pad, will affect the density and porosity of the brake pad.

[0106] In this embodiment, the friction layer has a low density, which is beneficial for absorbing sound waves and reducing brake drum noise. In a specific example, the density of the friction layer is 2.6 g / cm³. 3 2.65g / cm 3 2.7g / cm 3 2.75g / cm 3 2.8g / cm 3 wait.

[0107] In this embodiment, the high porosity is beneficial for absorbing sound waves and reducing brake drum noise. Specific examples show that the porosity of the friction layer is 20%, 21%, 22%, 23%, 24%, 25%, etc.

[0108] In this embodiment, the thickness of the friction layer is 8mm to 12mm. A friction layer that is too thin will affect braking performance and service life, while a friction layer that is too thick will make the brake pads too heavy and pose potential hazards to the vehicle's braking system. Specific examples show friction layer thicknesses of 8mm, 9mm, 10mm, 11mm, and 12mm. Further, the friction layer thickness is 10mm.

[0109] According to embodiments of this application, the brake pads satisfy at least one of the following:

[0110] (i) The bonding strength of the brake pads is 4MPa to 6MPa;

[0111] (ii) The compression rate of the brake pads is 0.85% to 1.10%;

[0112] (iii) The incidence of brake pad noise >70dB is 8.1% to 10.1%.

[0113] The brake pads provided in this application have high bonding strength, ranging from 4 MPa to 6 MPa. In a specific example, the bonding strength of the brake pads is 4.65 MPa to 5.25 MPa.

[0114] The brake pads provided in this application embodiment have a compression rate of 0.85% to 1.10%, which conforms to international standards (not exceeding 2%). Too low a compression rate can easily generate braking noise, while too high a compression rate will affect braking performance.

[0115] The brake pads provided in this application have good noise reduction performance, with a >70dB noise occurrence rate of 8.1% to 10.1%.

[0116] The fourth aspect of this application discloses a method for preparing brake pads, comprising:

[0117] Using the above-mentioned friction material, the raw materials of the friction material are mixed to obtain a mixture;

[0118] Brake pads are prepared by hot pressing, curing, and heat treatment of the mixed materials.

[0119] This application introduces a non-toxic, high-temperature resistant inorganic binder, which works in conjunction with an organic binder to bond reinforcing fibers, porous materials, and other fillers. The inorganic binder undergoes dehydration and condensation at a certain temperature to generate a three-dimensional network porous structure. The resulting brake pad mixture is then subjected to processes such as hot pressing, curing, and heat treatment to obtain a high-temperature resistant, low-noise brake pad.

[0120] According to the embodiments of this application, in the steps of hot pressing, curing and heat treatment of the mixture, the control parameters include at least one of the following (1) to (3):

[0121] (1) The hot pressing temperature is 150℃~170℃; in specific examples, the hot pressing temperature is 150℃, 155℃, 160℃, 165℃, 170℃, etc.

[0122] (2) The curing temperature is 200℃~250℃; in specific examples, the curing temperatures are 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, etc.

[0123] (4) The heat treatment temperature is 350℃~550℃, and the heat treatment time is 10min~60min. In specific examples, the heat treatment temperatures are 350℃, 400℃, 450℃, 500℃, 550℃, etc. In specific examples, the heat treatment times are 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, etc.

[0124] In this embodiment, the heat treatment temperature and heat treatment time meet the above conditions, which helps to balance the role requirements of inorganic and organic components in the composite binder, ensures that the organic binder will not fail at high temperature, and at the same time ensures that the organic binder can fully dehydrate and condense to form a porous network structure.

[0125] Under the above heat treatment temperature and time conditions, either a high-temperature, short-time treatment scheme or a low-temperature, long-time treatment scheme can be selected.

[0126] Therefore, according to the embodiments of this application, in the heat treatment step: the heat treatment temperature is 500℃~550℃, and the heat treatment time is 5min~15min; or, the heat treatment temperature is 350℃~400℃, and the heat treatment time is 60min~120min.

[0127] In specific examples, the heat treatment scheme at high temperature and short time involves heat treatment temperatures of 510℃, 520℃, 530℃, 540℃, and 550℃, etc., and heat treatment times of 5min, 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, and 15min, etc.

[0128] In specific examples, the low-temperature, long-duration heat treatment scheme uses heat treatment temperatures of 350℃, 360℃, 370℃, 380℃, 390℃, and 400℃, etc., and heat treatment times of 60min, 65min, 70min, 75min, 80min, 85min, 90min, 95min, 100min, 105min, 110min, 115min, and 120min, etc.

[0129] According to the embodiments of this application, the method for preparing brake pads specifically includes the following steps:

[0130] S1000: Preparation of friction layer mixture. The raw materials of the friction material described above are mixed to obtain the friction layer mixture. In a specific example, the raw materials of the friction material are placed in a plow-type mixer and stirred at 200 r / min to 1000 r / min for 20 min to 60 min until uniformly mixed to obtain the friction layer mixture.

[0131] S2000: Hot-press curing treatment. The friction layer mixture, the heat insulation layer material, and the steel backing are sequentially placed into a hot-press mold and hot-pressed to form the material, followed by curing. In a specific example, the steel backing, the heat insulation layer, and the friction layer powder are sequentially placed into a hot-press mold and hot-pressed at 150℃~170℃, followed by curing in an oven at 200℃~250℃.

[0132] S3000: Heat treatment. Finally, the brake pad product is obtained through a heat treatment process. In a specific example, the heat treatment process is carried out at a temperature of 350℃~550℃ for 10min~60min.

[0133] According to the fifth aspect of this application, a vehicle is provided having the above-described brake pads, or brake pads obtained by the above-described preparation method.

[0134] The vehicle proposed in this application embodiment has the above-mentioned brake pads, which are resistant to high temperatures and have a low braking noise rate, and exhibit good overall braking performance.

[0135] The following will explain the solution of this application with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0136] Example 1

[0137] 1. Composite adhesive:

[0138] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 3 parts zirconium oxide.

[0139] 2. Friction material:

[0140] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 3 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 30 parts barium sulfate.

[0141] 3. Brake pads:

[0142] Brake pad manufacturing method:

[0143] First, weigh the raw materials of the above friction material and put them into a plow-type mixer and stir at 1000 r / min for 60 min to obtain a friction layer mixture.

[0144] Then, the friction layer mixture, the heat insulation layer mixture (composed of binder (phenolic resin), reinforcing fibers (steel fiber, glass fiber and basalt fiber) and filler (rubber, friction powder and coke)) and the steel backing are placed into a hot press mold and hot-pressed at 160°C, and then cured in an oven at 200°C.

[0145] Finally, the brake pad product is obtained by heat treatment at 350℃ for 60 minutes.

[0146] Example 2

[0147] 1. Composite adhesive:

[0148] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 5 parts zirconium oxide.

[0149] 2. Friction material:

[0150] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 5 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 28 parts barium sulfate.

[0151] 3. Brake pads:

[0152] The preparation method of the brake pads is as shown in Example 1.

[0153] Example 3

[0154] 1. Composite adhesive:

[0155] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts zirconium oxide.

[0156] 2. Friction material:

[0157] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 26 parts barium sulfate.

[0158] 3. Brake pads:

[0159] The preparation method of the brake pads is as shown in Example 1.

[0160] Example 4

[0161] 1. Composite adhesive:

[0162] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts zirconium oxide.

[0163] 2. Friction material:

[0164] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 26 parts barium sulfate.

[0165] 3. Brake pads:

[0166] Brake pad manufacturing method:

[0167] First, weigh the raw materials of the friction material according to the above proportions and put them into a plow-type mixer. Stir at 1000r / min for 60min until they are evenly mixed to obtain the friction layer mixture.

[0168] Then, the friction layer mixture, the heat insulation layer mixture, and the steel backing are placed into a hot press mold and hot-pressed at 160°C, and then cured in an oven at 200°C.

[0169] Finally, the brake pad product is obtained by heat treatment at 450℃ for 30 minutes.

[0170] Example 5

[0171] 1. Composite adhesive:

[0172] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts zirconium oxide.

[0173] 2. Friction material:

[0174] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 26 parts barium sulfate.

[0175] 3. Brake pads:

[0176] Brake pad manufacturing method:

[0177] First, weigh the raw materials of the friction material according to the above proportions and put them into a plow-type mixer. Stir at 1000r / min for 60min until they are evenly mixed to obtain the friction layer mixture.

[0178] Then, the friction layer mixture, the heat insulation layer mixture, and the steel backing are placed into a hot press mold and hot-pressed at 160°C, and then cured in an oven at 200°C.

[0179] Finally, the brake pad product is obtained by heat treatment at 550℃ for 15 minutes.

[0180] Example 6

[0181] 1. Composite adhesive:

[0182] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts alumina.

[0183] 2. Friction material:

[0184] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts alumina, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 26 parts barium sulfate.

[0185] 3. Brake pads:

[0186] Brake pad manufacturing method:

[0187] First, weigh the raw materials of the friction material according to the above proportions and put them into a plow-type mixer. Stir at 1000r / min for 60min until they are evenly mixed to obtain the friction layer mixture.

[0188] Next, the friction layer mixture, the heat insulation layer mixture, and the steel backing are placed into a hot press mold and hot-pressed at 160°C, and then cured in an oven at 200°C.

[0189] Then, the brake pad product is obtained by heat treatment at 350℃ for 60 minutes.

[0190] Example 7

[0191] 1. Composite adhesive:

[0192] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts alumina.

[0193] 2. Friction material:

[0194] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts alumina, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 26 parts barium sulfate.

[0195] 3. Brake pads:

[0196] Brake pad manufacturing method:

[0197] First, weigh the raw materials of the friction material according to the above proportions and put them into a plow-type mixer. Stir at 1000r / min for 60min until they are evenly mixed to obtain the friction layer mixture.

[0198] Then, the friction layer mixture, the heat insulation layer mixture, and the steel backing are placed into a hot press mold and hot-pressed at 160°C, and then cured in an oven at 200°C.

[0199] Finally, the brake pad product is obtained by heat treatment at 450℃ for 30 minutes.

[0200] Example 8

[0201] 1. Composite adhesive:

[0202] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts alumina.

[0203] 2. Friction material:

[0204] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts alumina, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 26 parts barium sulfate.

[0205] 3. Brake pads:

[0206] Brake pad manufacturing method:

[0207] First, weigh the friction materials according to the above proportions and put them into a plow-type mixer. Stir at 1000 r / min for 60 min until they are evenly mixed to obtain the friction layer mixture.

[0208] Then, the friction layer mixture, the heat insulation layer mixture, and the steel backing are placed into a hot press mold and hot-pressed at 160°C, and then cured in an oven at 200°C.

[0209] Finally, the brake pad product is obtained by heat treatment at 550℃ for 15 minutes.

[0210] Example 9

[0211] 1. Composite adhesive:

[0212] The composite adhesive consists of 4 parts boron-modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts alumina.

[0213] 2. Friction material:

[0214] Composition of friction material: 4 parts boron-modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts alumina, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 26 parts barium sulfate.

[0215] 3. Brake pads:

[0216] Brake pad manufacturing method:

[0217] First, weigh the above materials according to the proportions and put them into a plow-type mixer. Stir at 1000r / min for 60min until they are evenly mixed to obtain the friction layer mixture.

[0218] Then, the friction layer mixture, the heat insulation layer mixture, and the steel backing are placed into a hot press mold and hot-pressed at 160°C, and then cured in an oven at 200°C.

[0219] Finally, the brake pad product is obtained by heat treatment at 550℃ for 15 minutes.

[0220] Example 10

[0221] 1. Composite adhesive:

[0222] The composite adhesive consists of 4 parts unmodified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts alumina.

[0223] 2. Friction material:

[0224] Composition of friction material: 4 parts unmodified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts alumina, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 10 parts flake graphite, 5 parts expanded graphite, 5 parts calcium silicate, 3 parts vermiculite, 2 parts nitrile rubber, and 30 parts barium sulfate.

[0225] 3. Brake pads:

[0226] Brake pad manufacturing method:

[0227] First, weigh the raw materials of the above friction material and put them into a plow-type mixer and stir at 1000 r / min for 60 min to obtain a friction layer mixture.

[0228] Then, the friction layer mixture, the heat insulation layer mixture, and the steel backing are placed into a hot press mold and hot-pressed at 160°C, and then cured in an oven at 200°C.

[0229] Finally, the brake pad product is obtained by heat treatment at 550℃ for 15 minutes.

[0230] Example 11

[0231] 1. Composite adhesive:

[0232] The composite binder consists of 5 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 3 parts zirconium oxide.

[0233] 2. Friction material:

[0234] Composition of friction material: 5 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 5 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 3 parts vermiculite, 5 parts calcium silicate, 5 parts expanded graphite, 10 parts flake graphite, 2 parts nitrile rubber, and 27 parts barium sulfate.

[0235] 3. Brake pads:

[0236] The preparation method of the brake pads is as shown in Example 1.

[0237] Comparative Example 1

[0238] 1. Single adhesive:

[0239] The inorganic binder consists of 10 parts aluminum dihydrogen phosphate and 3 parts zirconium oxide.

[0240] 2. Friction material:

[0241] Composition of friction material: 10 parts aluminum dihydrogen phosphate, 3 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 10 parts flake graphite, 5 parts expanded graphite, 5 parts calcium silicate, 3 parts vermiculite, 2 parts nitrile rubber, and 34 parts barium sulfate.

[0242] 3. Brake pads:

[0243] The preparation method of the brake pads is as shown in Example 1.

[0244] Comparative Example 2

[0245] 1. Single adhesive:

[0246] Composition of the organic binder: 4 parts cashew nut shell oil modified phenolic resin.

[0247] 2. Friction material:

[0248] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 3 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 10 parts flake graphite, 5 parts expanded graphite, 5 parts calcium silicate, 3 parts vermiculite, 2 parts nitrile rubber, and 40 parts barium sulfate.

[0249] 3. Brake pads:

[0250] The preparation method of the brake pads is as shown in Example 1.

[0251] Comparative Example 3

[0252] 1. Composite adhesive:

[0253] Composition of the composite adhesive: 4 parts cashew nut shell oil modified phenolic resin and 10 parts aluminum dihydrogen phosphate.

[0254] 2. Friction material:

[0255] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 10 parts flake graphite, 5 parts expanded graphite, 5 parts calcium silicate, 3 parts vermiculite, 2 parts nitrile rubber, and 33 parts barium sulfate.

[0256] 3. Brake pads:

[0257] The preparation method of the brake pads is as shown in Example 1.

[0258] Comparative Example 4

[0259] 1. Composite adhesive:

[0260] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 9 parts zirconium oxide.

[0261] 2. Friction material:

[0262] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 9 parts zirconium oxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 10 parts flake graphite, 5 parts expanded graphite, 5 parts calcium silicate, 3 parts vermiculite, 2 parts nitrile rubber, and 24 parts barium sulfate.

[0263] 3. Brake pads:

[0264] The preparation method of the brake pads is as shown in Example 1.

[0265] Comparative Example 5

[0266] 1. Composite adhesive:

[0267] Composition of the composite adhesive: 4 parts cashew nut shell oil modified phenolic resin and 10 parts sodium silicate.

[0268] 2. Friction material:

[0269] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts sodium silicate, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 10 parts flake graphite, 5 parts expanded graphite, 5 parts calcium silicate, 3 parts vermiculite, 2 parts nitrile rubber, and 33 parts barium sulfate.

[0270] 3. Brake pads:

[0271] The preparation method of the brake pads is as shown in Example 1.

[0272] Comparative Example 6

[0273] 1. Composite adhesive:

[0274] The composite binder consists of: 4 parts cashew nut shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, and 7 parts aluminum hydroxide.

[0275] 2. Friction material:

[0276] Composition of friction material: 4 parts cashew shell oil modified phenolic resin, 10 parts aluminum dihydrogen phosphate, 7 parts aluminum hydroxide, 15 parts steel fiber, 10 parts copper fiber, 3 parts aramid fiber, 10 parts flake graphite, 5 parts expanded graphite, 5 parts calcium silicate, 3 parts vermiculite, 2 parts nitrile rubber, and 26 parts barium sulfate.

[0277] 3. Brake pads:

[0278] The preparation method of the brake pads is as shown in Example 1.

[0279] Performance testing

[0280] I. Testing Method:

[0281] 1. Scanning electron microscope (SEM) was used to test the morphology of the composite adhesive provided in Example 1.

[0282] 2. Adhesion strength, the test standard is GB / T 22309, used to test the brake pads provided in each embodiment and comparative example.

[0283] 3. Compression ratio, the test standard is ISO 6310, used to test the brake pads provided in each embodiment and comparative example.

[0284] 4. Noise generation rate, the test standard is SAE J2521, used to test the brake pads provided in each embodiment and comparative example.

[0285] II. Test Results:

[0286] 1. Morphological characterization of the composite adhesive after curing.

[0287] The composite adhesive from Example 1 was mixed and then heat-treated at 350°C for 1 hour. The resulting sample was characterized by SEM.

[0288] The results are as follows Figure 2 As shown, the phosphate binder and resin are bonded together, and the surface exhibits a distinct porous structure.

[0289] 2. The test results of high-temperature shear strength, compressive strength and noise occurrence rate are shown in Table 1.

[0290] Table 1 shows the test results of the bond strength, compression ratio, and >70 dB noise generation rate of the brake pads provided in each embodiment and comparative example.

[0291]

[0292] The test results of the high-temperature shear strength, compressive strength and noise generation rate of the brake pads provided in Examples 1-10 and Comparative Examples 1-6 are shown in Table 1.

[0293] As shown in Table 1, the brake pads prepared using the composite adhesive thermal insulation material provided by this invention exhibit high bonding strength and excellent noise reduction performance. Specifically, the brake pads provided in Examples 1-10 have a bonding strength of 4.65 MPa to 5.25 MPa, a compression ratio of 0.85% to 1.10%, a noise generation rate >70 dB of 8.1% to 10.1%, and a density of 2.60 to 2.70 g / cm³. 3The porosity is 21.1%–23.5%. Comparing the data from Examples 1–10 and Comparative Examples 1–2 shows that, compared to a single binder, the composite binder exhibits both strong adhesion and low noise generation. Comparing the data from Examples 1–5 and Comparative Examples 1–3 shows that the content and type of curing agent, as well as the content of phenolic resin, affect the compressibility and porosity of the friction layer, thereby affecting the braking noise generation rate of the brake pads. Comparing the data from Example 1 and Comparative Examples 3–6 shows that non-phosphate binders, excessive curing agents, etc., all affect the bonding strength and noise generation rate of the brake pads.

[0294] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A composite adhesive, characterized in that, include: Organic adhesives; Inorganic binders, wherein the inorganic binders include phosphates; Curing agent, said curing agent comprising metal oxide; The mass ratio of the inorganic binder to the curing agent is 10:(3-7).

2. The composite adhesive according to claim 1, characterized in that, The mass ratio of the inorganic binder to the curing agent is 10:(5-7).

3. The composite adhesive according to claim 1 or 2, characterized in that, The metal oxide includes at least one of zirconium oxide, aluminum oxide and zinc oxide; And / or, the phosphate includes at least one of aluminum dihydrogen phosphate, zinc dihydrogen phosphate, and calcium dihydrogen phosphate.

4. The composite adhesive according to any one of claims 1 to 3, characterized in that, The organic binder includes phenolic resin binders.

5. The composite adhesive according to any one of claims 1 to 4, characterized in that, The organic binder includes at least one of unmodified phenolic resin, nitrile-modified phenolic resin, cashew nut shell oil-modified phenolic resin, melamine-modified phenolic resin, molybdenum-modified phenolic resin, and boron-modified phenolic resin; further, the organic binder includes cashew nut shell oil-modified phenolic resin and / or boron-modified phenolic resin.

6. The composite adhesive according to any one of claims 1 to 5, characterized in that, By weight, it includes: Organic binder, 4 to 5 parts; Inorganic binder, 10 to 11 parts; Hardener, 3 to 7 parts.

7. A friction material, characterized in that, The raw material composition includes the composite adhesive as described in any one of claims 1 to 6.

8. The friction material according to claim 7, characterized in that, The raw material composition also includes porous materials, reinforcing fibers, and fillers; the composite binder has a mass percentage of 17wt% to 21wt%.

9. The friction material according to claim 8, characterized in that, The raw material composition satisfies any one of the following (1) to (3): (1) The porous material includes at least one of expanded graphite, vermiculite and calcium silicate; (2) The reinforcing fiber includes at least one of steel fiber, copper fiber, aramid fiber, carbon fiber and glass fiber; (3) The filler includes at least one of flake graphite, silica powder, nitrile rubber and barium sulfate.

10. The friction material according to any one of claims 7 to 9, characterized in that, By weight, the raw material composition includes: Composite adhesive, 17 to 23 parts; Porous material, 10 to 19 parts; Reinforcing fibers, 17 to 34 parts; Filler, 27 to 54 parts.

11. The friction material according to any one of claims 7 to 10, characterized in that, By weight, the raw material composition includes: Cashew shell oil modified phenolic resin, 4 to 5 parts; 10 to 11 parts of inorganic binder; 3 to 7 parts curing agent; 10 to 20 parts steel fiber; 5 to 10 parts copper fiber; 2 to 4 parts aramid fiber; 2 to 4 parts vermiculite; 3-5 parts calcium silicate; 5 to 10 parts expanded graphite; 5 to 10 parts of flake graphite; 2 to 4 parts of nitrile rubber; Barium sulfate, 20 to 40 parts.

12. A brake pad, characterized in that, It includes a friction layer, the material of which includes the friction material according to any one of claims 7 to 11.

13. The brake pad according to claim 12, characterized in that, The friction layer satisfies at least one of the following: (a) The density of the friction layer is 2.6 g / cm³. 3 ~2.8g / cm 3 ; (b) The porosity of the friction layer is 20% to 25%; (c) The thickness of the friction layer is 8 mm to 12 mm.

14. The brake pad according to claim 12 or 13, characterized in that, The brake pads satisfy at least one of the following: (i) The bonding strength of the brake pads is 4 MPa to 6 MPa; (ii) The compression rate of the brake pads is 0.85% to 1.10%; (iii) The occurrence rate of >70dB noise in the brake pads is 8.1% to 10.1%.

15. A method for preparing brake pads, characterized in that, include: Using the friction material according to any one of claims 7 to 11, the raw materials of the friction material are mixed to obtain a mixture; Brake pads are prepared by hot pressing, curing, and heat treatment of the mixture.

16. The preparation method according to claim 15, characterized in that, In the steps of hot pressing, curing and heat treatment of the mixture, the control parameters include at least one of the following (1) to (3): (1) The hot pressing temperature is 150℃~170℃; (2) The curing temperature is 200℃~250℃; (3) The heat treatment temperature is 350℃~550℃ and the heat treatment time is 15min~60min.

17. The preparation method according to claim 15 or 16, characterized in that, In the heat treatment step: The heat treatment temperature is 500℃~550℃, and the heat treatment time is 5min~15min; Alternatively, the heat treatment temperature is 350℃~400℃, and the heat treatment time is 60min~120min.

18. A vehicle, characterized in that, The brake pads are those according to any one of claims 12 to 14, or those obtained by the preparation method according to any one of claims 15 to 17.

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