Liquid-core fiber and low PM10 emission friction material based on liquid-core fiber

Abstract

The present invention relates to a liquid-core fiber and a low PM10 emission friction material based on the liquid-core fiber. The liquid-core fiber comprises hollow fibers, a liquid, and an epoxy resin. The liquid is filled in the cavity inside the hollow fibers, and the epoxy resin is coated on the surface and both ends of the hollow fibers to prevent the liquid from flowing out. The friction material comprises 13-33 parts of liquid-core fibers, 10-15 parts of adhesive, 15-30 parts of friction modifier, and 25-55 parts of friction filler. The viscous liquid released when the liquid-core fibers are worn reduces the fine particle dust emission of the friction material, so that it meets increasingly stringent environmental protection requirements. At the same time, the liquid in the liquid-core fibers also has a damping effect, which can significantly enhance the noise absorption effect of the friction material.

Description

Technical Field

[0001] The present invention relates to multiple technical fields such as composite materials and environmental protection, and in particular to a liquid-core fiber and a low PM10 emission friction material based on the liquid-core fiber. Background Art

[0002] During use, automotive friction materials are subject to alternating normal pressure, shear stress, and braking heat. These factors combine to cause wear, and most of this wear material is typically emitted into the air as PM10, contributing to air pollution. In recent years, with growing environmental awareness, countries have established requirements for dust emissions from automotive friction materials during use. For example, the Euro 7 standard currently sets a PM10 friction dust emission limit of 7mg / km for passenger cars, which is set to reach 3mg / km by 2035. Such stringent regulations pose significant challenges to the research and development of friction materials.

[0003] Friction materials currently available on the market are generally divided into organic, asbestos-free, and metal-free friction materials, and low-metal or semi-metal friction materials. Organic, asbestos-free, and metal-free friction materials are primarily reinforced with aramid, mineral fibers, and the like as a matrix, while low-metal or semi-metal friction materials are primarily reinforced with various metal fibers as a matrix. Fillers used in friction materials generally include barite, alumina, calcium carbonate, graphite, coke, sulfides, and the like. These materials play an important role in maintaining structural strength and providing friction and wear performance, but they also cause wear and tear during braking, resulting in the shedding of wear debris. The shed wear products are in the form of fine particles, which are a major cause of air pollution. Therefore, there is an urgent need to develop a friction material with low PM10 emissions to reduce the air pollution caused by friction plates during use and better meet regulatory requirements. Summary of the Invention

[0004] The primary purpose of this invention is to address the aforementioned issues of the prior art by providing a low-PM10 emission friction material based on liquid-core fibers. The viscous liquid released by the liquid-core fibers during wear reduces dust emissions from the friction material, thereby meeting increasingly stringent environmental protection requirements. Furthermore, the liquid in the liquid-core fibers also has a damping effect, significantly enhancing the noise absorption of the friction material. To achieve this objective, the present invention employs the following technical solutions:

[0005] A liquid-core fiber comprises a hollow fiber and a liquid, wherein the liquid is filled in the cavity inside the hollow fiber.

[0006] Furthermore, the liquid-core fiber also includes epoxy resin, which is coated on the surface and both ends of the hollow fiber to prevent the liquid inside from being released prematurely.

[0007] Furthermore, the hollow fibers are selected from at least one of hollow carbon fibers and hollow halloysite nanotubes, and the liquid is heavy oil. Hollow carbon fibers and hollow halloysite nanotubes have advantages such as high strength and excellent wear resistance. Adsorbing heavy oil improves friction and wear performance while also reducing PM10 emissions. They have a superior adsorption effect on coarse (5-10 μm) and fine (<5 μm) wear debris particles, respectively.

[0008] The present invention also provides a method for preparing the above-mentioned liquid-core fiber. The specific process is as follows: hollow carbon fibers or hollow halloysite nanotubes are placed in a sealed container, vacuumed, and then high-temperature heavy oil is added for adsorption. Finally, epoxy resin is added to coat and cap the hollow fibers.

[0009] Furthermore, the temperature of the high-temperature heavy oil is 80-120° C., and the adsorption is performed at this temperature.

[0010] Furthermore, the epoxy resin is specifically a liquid UV-curable epoxy resin, including bisphenol A epoxy resin and alicyclic epoxy resin, etc. After the epoxy resin is added, the mixture is taken out from the sealed container and dispersed, and then irradiated with UV light to fully cure it.

[0011] A third object of the present invention is to provide a low PM10 emission friction material based on liquid-core fiber, the friction material comprising liquid-core fiber, adhesive, friction modifier, and friction filler.

[0012] Furthermore, the adhesive is specifically graphene-enhanced polyimide resin particles, 100% of which pass through a 320-mesh screen. This resin is selected because it has the advantages of high temperature resistance and low wear, which can reduce the wear rate of the friction material and reduce the wear of the material itself.

[0013] Furthermore, the graphene content in the graphene-enhanced polyimide resin is 0.5wt%-1wt%, and the selected graphene is specifically graphene oxide with a particle size of less than 1 micron.

[0014] Furthermore, the friction modifier is selected from at least one of stannous sulfide, graphite flakes, and nano-silicon carbide wafers.

[0015] Furthermore, the nano-SiC wafer has a diameter of 0.1mm-0.3mm and a thickness of 300-500nm. The nano-SiC wafer can play a two-dimensional reinforcing role, preventing abrasive particles from invading the surface of the friction material, thereby improving the resistance to abrasive particles and fatigue wear.

[0016] Furthermore, the friction filler is selected from at least one of barium sulfate and potassium sodium hexatitanate.

[0017] Furthermore, the friction material comprises, by weight, 13-33 parts of liquid-core fiber, 10-15 parts of adhesive, 15-30 parts of friction modifier, and 25-55 parts of friction filler.

[0018] Furthermore, the friction material comprises, by weight, 10-15 parts of liquid-core carbon fibers, 3-8 parts of liquid-core halloysite nanotubes, 10-15 parts of graphene-enhanced polyimide resin, 5-10 parts of stannous sulfide, 5-10 parts of phosphorus flake graphite, 5-10 parts of nano-silicon carbide chips, 10-25 parts of barium sulfate, and 15-30 parts of potassium sodium hexatitanate.

[0019] A fourth object of the present invention is to provide a method for preparing the above-mentioned friction material with low dust emission, comprising: preparing raw materials according to a formula, mixing the raw materials and then performing molding.

[0020] Furthermore, the raw materials are mixed uniformly in a high-speed mixer at a mixing speed of 2000-5000 rpm for 3-5 minutes, and the temperature during molding is 135-150°C and the pressure is 200-500 kg / cm 2 The molding time is 3-10 minutes, and the green body obtained by molding is placed at 145-160° C. and cured for 2-5 hours to obtain a friction material with excellent performance.

[0021] To address the environmental pollution caused by dust emissions during the use of friction materials, the inventors developed a liquid-core fiber as a key, core component of the friction material. When the friction material wears, the liquid-core fiber breaks and releases a viscous liquid, which binds fine wear debris particles into larger particles and removes them from the friction surface. Because the liquid is released synchronously with the wear process, this action continues as wear progresses, providing continuous cohesion on the friction surface and ensuring the continued effectiveness of the PM10 reduction function. When braking is complete, the wear debris and transfer materials from the friction interface coat the friction surface, thereby covering the worn end faces of the hollow fiber tubes and protecting the liquid within the tubes.

[0022] Compared with existing similar technologies, the advantages of this invention are mainly reflected in the following aspects:

[0023] (1) The low dust emission friction material provided by the present invention uses graphene-enhanced polyimide resin as a bonding component and is reinforced with liquid-core carbon fibers and liquid-core halloysite nanotubes, respectively. During normal use, the liquid in the liquid-core fibers plays a damping role, significantly improving the noise absorption function of the friction material.

[0024] (2) The liquid-core carbon fibers and liquid-core halloysite nanotubes in the low-dust emission friction material formula of the present invention also play a key role in reducing fine particle dust emissions. They mainly utilize the large amount of viscous liquid released during normal wear to aggregate and bond small wear debris particles into particles larger than PM10, thereby preventing PM10 pollution in the air.

[0025] (3) The low dust emission friction material has a simple preparation process and excellent performance. While ensuring the friction performance of the friction material, it greatly reduces the emission of PM10 dust particles and meets the stringent environmental protection requirements of various countries. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to fully understand the technical solutions and beneficial effects of the present invention, further description will be given below in conjunction with specific embodiments.

[0027] Example 1

[0028] The formulation of the low dust emission friction material is:

[0029] 10 parts liquid core carbon fiber;

[0030] 3 parts liquid-core halloysite nanotubes;

[0031] 15 parts of graphene-reinforced polyimide resin;

[0032] 20 parts of barium sulfate;

[0033] 22 parts of potassium sodium hexatitanate;

[0034] 10 parts of stannous sulfide;

[0035] 10 parts of graphite flakes;

[0036] 10 nano-SiC wafers (0.2 mm in diameter, approximately 350 nm in thickness).

[0037] The preparation and method of the low dust emission friction material are as follows:

[0038] (1) 0.5 parts of graphene oxide with a particle size of less than 1 μm and 99.5 parts of polyimide resin were added to a ball mill and ball milled for 20 minutes to mix the two uniformly to obtain a graphene-reinforced polyamide resin.

[0039] (2) Hollow carbon fibers were prepared using coaxial electrospinning technology. 80 parts of hollow carbon fibers were placed in a vacuum reactor and evacuated. 10 parts of heavy oil at 80°C were then slowly injected into the reactor while stirring to allow the hollow carbon fibers to fully absorb the heavy oil. After the excess heavy oil that was not absorbed was discharged, 10 parts of liquid UV-curable epoxy resin were injected into the reactor to coat the surface and end faces of the hollow carbon fibers. Finally, the treated hollow carbon fibers were removed from the reactor, dispersed by airflow, and then placed under UV light for curing to obtain liquid-core carbon fibers filled with heavy oil.

[0040] Using hollow halloysite nanotubes and heavy oil as raw materials, heavy oil-filled liquid-core halloysite nanotubes were prepared according to the same method.

[0041] (3) Prepare the materials according to the formula, put the liquid core carbon fiber, liquid core halloysite nanotubes, graphene-enhanced polyimide resin, barium sulfate, potassium sodium hexatitanate, stannous sulfide, phosphorus flake graphite, and nano silicon carbide chips into a high-speed mixer, and mix them at a speed of 3000 rpm for 3 minutes to obtain a friction material mixture. Put the friction material mixture into a hot mold heated to 140°C in advance, close the mold, and pressurize it to 400 kg / cm 2 The mixture was kept for 5 minutes, and the mold was opened to obtain a green body, which was then heated to 145° C. and cured for 5 hours to obtain the target friction material.

[0042] Example 2

[0043] The formulation of the low dust emission friction material is:

[0044] 13 parts liquid core carbon fiber;

[0045] 6 parts liquid-core halloysite nanotubes;

[0046] 12 parts of graphene-reinforced polyimide resin;

[0047] 25 parts of barium sulfate;

[0048] 18 parts of potassium sodium hexatitanate;

[0049] 8 parts of stannous sulfide;

[0050] 8 parts of graphite flakes;

[0051] 10 nano-SiC wafers (0.2 mm in diameter, approximately 500 nm in thickness).

[0052] The preparation and method of the low dust emission friction material are as follows:

[0053] (1) 1 part of graphene oxide with a particle size of less than 1 μm and 99 parts of polyimide resin were added to a ball mill and ball milled for 20 minutes to mix the two uniformly to obtain a graphene-reinforced polyamide resin.

[0054] (2) Hollow carbon fibers were prepared using coaxial electrospinning technology. 85 parts of hollow carbon fibers were placed in a vacuum reactor and evacuated. 7.5 parts of heavy oil at 80°C were then slowly injected into the reactor while stirring to allow the hollow carbon fibers to fully absorb the heavy oil. After the excess heavy oil that was not absorbed was discharged, 7.5 parts of liquid UV-curable epoxy resin were injected into the reactor to coat the surface and end faces of the hollow fibers. Finally, the hollow carbon fibers were removed from the reactor, dispersed by air flow, and then placed under UV light for curing to obtain liquid-core carbon fibers filled with heavy oil.

[0055] Using hollow halloysite nanotubes and heavy oil as raw materials, heavy oil-filled liquid-core halloysite nanotubes were prepared according to the same method.

[0056] (3) Prepare the materials according to the formula, put the liquid core carbon fiber, liquid core halloysite nanotubes, graphene-enhanced polyimide resin, barium sulfate, potassium sodium hexatitanate, stannous sulfide, phosphorus flake graphite, and nano silicon carbide chips into a high-speed mixer, and mix them at a speed of 3000 rpm for 3 minutes to obtain a friction material mixture. Put the friction material mixture into a hot mold preheated to 140°C, close the mold, and pressurize it to 250 kg / cm 2 The mold was opened after 8 minutes to obtain a green body, which was then heated to 150°C and cured for 3 hours to obtain the target friction material.

[0057] Example 3

[0058] The formulation of the low dust emission friction material is:

[0059] 15 parts of liquid core carbon fiber;

[0060] 6 parts liquid-core halloysite nanotubes;

[0061] 10 parts of graphene-reinforced polyimide resin;

[0062] 30 parts of barium sulfate;

[0063] 19 parts of potassium sodium hexatitanate;

[0064] 5 parts of stannous sulfide;

[0065] 5 parts of graphite flakes;

[0066] 10 nano-SiC wafers (0.25 mm in diameter, approximately 400 nm in thickness).

[0067] The preparation and method of the low dust emission friction material are as follows:

[0068] (1) 0.7 parts of graphene oxide with a particle size of less than 1 μm and 99.3 parts of polyimide resin were added to a ball mill and ball milled for 20 minutes to mix the two uniformly to obtain a graphene-reinforced polyamide resin.

[0069] (2) Hollow carbon fibers were prepared using coaxial electrospinning technology. 90 parts of hollow carbon fibers were placed in a vacuum reactor and evacuated. 5 parts of heavy oil at 80°C were then slowly injected into the reactor while stirring to allow the hollow carbon fibers to fully absorb the heavy oil. After the excess heavy oil that was not absorbed was discharged, 5 parts of liquid UV-curable epoxy resin were injected into the reactor to coat the surface and end faces of the hollow fibers. Finally, the hollow carbon fibers were removed from the reactor, dispersed by air flow, and then placed under UV light for curing to obtain liquid-core carbon fibers filled with heavy oil.

[0070] Using hollow halloysite nanotubes and heavy oil as raw materials, heavy oil-filled liquid-core halloysite nanotubes were prepared according to the same method.

[0071] (3) Prepare the materials according to the formula, put the liquid core carbon fiber, liquid core halloysite nanotubes, graphene-enhanced polyimide resin, barium sulfate, potassium sodium hexatitanate, stannous sulfide, phosphorus flake graphite, and nano silicon carbide chips into a high-speed mixer, and mix them at a speed of 3000 rpm for 3 minutes to obtain a friction material mixture. Put the friction material mixture into a hot mold heated to 150°C in advance, close the mold, and pressurize it to 400 kg / cm 2 The mold was opened after 5 minutes to obtain a green body, which was then heated to 160°C and cured for 2 hours to obtain the target friction material.

[0072] Comparative Example 1

[0073] The formulation of the low dust emission friction material is:

[0074] 10 parts of uncapped liquid-core carbon fibers;

[0075] 3 parts of uncapped liquid-core halloysite nanotubes;

[0076] 15 parts of graphene-reinforced polyimide resin;

[0077] 20 parts of barium sulfate;

[0078] 22 parts of potassium sodium hexatitanate;

[0079] 10 parts of stannous sulfide;

[0080] 10 parts of graphite flakes;

[0081] 10 nano-SiC wafers (0.2 mm in diameter, approximately 350 nm in thickness).

[0082] The preparation and method of the low dust emission friction material are as follows:

[0083] (1) 0.5 parts of graphene oxide with a particle size of less than 1 μm and 99.5 parts of polyimide resin were added to a ball mill and ball milled for 20 minutes to mix the two uniformly to obtain a graphene-reinforced polyamide resin.

[0084] (2) Hollow carbon fibers were prepared using coaxial electrospinning technology. 80 parts of hollow carbon fibers were placed in a vacuum reactor and evacuated. 10 parts of heavy oil at 80°C were then slowly injected into the reactor while stirring to allow the hollow carbon fibers to fully absorb the heavy oil. The solid matter was removed and the excess heavy oil that was not absorbed was separated to obtain liquid-core carbon fibers filled with heavy oil and not capped.

[0085] Using hollow halloysite nanotubes and heavy oil as raw materials, heavy oil-filled uncapped liquid-core halloysite nanotubes were prepared according to the same method.

[0086] (3) Prepare the materials according to the formula, put the uncapped liquid core carbon fiber, uncapped liquid core halloysite nanotube, graphene-enhanced polyimide resin, barium sulfate, potassium sodium hexatitanate, stannous sulfide, phosphorus flake graphite, and nano-silicon carbide wafer into a high-speed mixer, and mix them at a speed of 3000 rpm for 3 minutes to obtain a friction material mixture. Put the friction material mixture into a hot mold preheated to 140°C, close the mold, and pressurize it to 400 kg / cm 2 The mixture was kept for 5 minutes, and the mold was opened to obtain a green body, which was then heated to 145° C. and cured for 5 hours to obtain the target friction material.

[0087] Comparative Example 2

[0088] The formulation of the low dust emission friction material is:

[0089] 13 parts liquid core carbon fiber;

[0090] 15 parts of graphene-reinforced polyimide resin;

[0091] 20 parts of barium sulfate;

[0092] 22 parts of potassium sodium hexatitanate;

[0093] 10 parts of stannous sulfide;

[0094] 10 parts of graphite flakes;

[0095] 10 nano-SiC wafers (0.2 mm in diameter, approximately 350 nm in thickness).

[0096] The preparation and method of the low dust emission friction material are as follows:

[0097] (1) 0.5 parts of graphene oxide with a particle size of less than 1 μm and 99.5 parts of polyimide resin were added to a ball mill and ball milled for 20 minutes to mix the two uniformly to obtain a graphene-reinforced polyamide resin.

[0098] (2) Hollow carbon fibers were prepared using coaxial electrospinning technology. 80 parts of hollow carbon fibers were placed in a vacuum reactor and evacuated. 10 parts of heavy oil at 80°C were then slowly injected into the reactor while stirring to allow the hollow carbon fibers to fully absorb the heavy oil. After the excess heavy oil that was not absorbed was discharged, 10 parts of liquid UV-curable epoxy resin were injected into the reactor to coat the surface and end faces of the hollow fibers. Finally, the treated hollow carbon fibers were removed from the reactor, dispersed by airflow, and then placed under UV light for curing to obtain liquid-core carbon fibers filled with heavy oil.

[0099] (3) Prepare the materials according to the formula, put the liquid core carbon fiber, graphene reinforced polyimide resin, barium sulfate, potassium sodium hexatitanate, stannous sulfide, phosphorus flake graphite, and nano silicon carbide wafer into a high-speed mixer, and mix them at a speed of 3000 rpm for 3 minutes to obtain a friction material mixture. Put the friction material mixture into a hot mold heated to 140°C in advance, close the mold, and pressurize it to 400 kg / cm 2 The mixture was kept for 5 minutes, and the mold was opened to obtain a green body, which was then heated to 145° C. and cured for 5 hours to obtain the target friction material.

[0100] Comparative Example 3

[0101] The formulation of the low dust emission friction material is:

[0102] 10 parts of ordinary carbon fiber;

[0103] 3 parts ordinary halloysite nanotubes;

[0104] 15 parts of graphene-reinforced polyimide resin;

[0105] 20 parts of barium sulfate;

[0106] 22 parts of potassium sodium hexatitanate;

[0107] 10 parts of stannous sulfide;

[0108] 10 parts of graphite flakes;

[0109] 10 nano-SiC wafers (0.2 mm in diameter, approximately 350 nm in thickness).

[0110] The preparation and method of the low dust emission friction material are as follows:

[0111] (1) 0.5 parts of graphene oxide with a particle size of less than 1 μm and 99.5 parts of polyimide resin were added to a ball mill and ball milled for 20 minutes to mix the two uniformly to obtain a graphene-reinforced polyamide resin.

[0112] (2) Prepare the materials according to the formula, put carbon fiber, halloysite nanotubes, graphene-enhanced polyimide resin, barium sulfate, potassium sodium hexatitanate, stannous sulfide, graphite flakes, and nano-silicon carbide chips into a high-speed mixer, and mix them at a speed of 3000 rpm for 3 minutes to obtain a friction material mixture. Put the friction material mixture into a hot mold preheated to 140°C, close the mold, and pressurize it to 400 kg / cm 2 The mixture was kept for 5 minutes, and the mold was opened to obtain a green body, which was then heated to 145° C. and cured for 5 hours to obtain the target friction material.

[0113] To fully understand the performance of the friction materials produced in Examples 1-3 and Comparative Examples 1-3, a series of tests were conducted on brake pads (120*44*13mm) made from these materials. Various friction properties, including average friction coefficient, first-fade friction coefficient, second-fade friction coefficient, and weight wear, were tested according to SAE J2522. PM10 friction dust emissions were also measured using the GTRWLTP test method. The test results for the various samples are shown in Table 1.

[0114] Table 1 Comparison of performance test results of different brake pads

[0115]

[0116] As shown in Table 1, compared to the uncapped liquid-core fiber in Comparative Example 1, the single liquid-core fiber in Comparative Example 2, and the conventional fiber without a liquid core in Comparative Example 3, the friction materials produced using UV-curable epoxy resin-coated and end-capped liquid-core fibers in Examples 1-3 of the present invention significantly reduced PM10 dust emissions, maintained a stable friction coefficient, and exhibited reduced wear. This is because the uncapped liquid-core fibers in Comparative Example 1 prematurely drained the liquid stored within them. This premature, concentrated discharge not only reduced the friction coefficient but also prevented wear particles from agglomerating later due to the premature emptying of the liquid from the fibers, ultimately resulting in significant PM10 emissions. The single liquid-core fibers in Comparative Example 2 lacked the ability to agglomerate fine dust particles, failing to achieve optimal PM10 emission reductions. The conventional fibers in Comparative Example 3 completely lacked dust agglomeration, resulting in higher PM10 emissions.

Claims

1. A liquid-core fiber, characterized in that: The liquid-core fiber includes a hollow fiber, a liquid, and an epoxy resin. The liquid is filled in the cavity inside the hollow fiber, and the epoxy resin is coated on the surface and both ends of the hollow fiber. The preparation method of the liquid-core fiber includes: placing the hollow fiber in a sealed container, adding liquid for adsorption after vacuuming, and finally adding epoxy resin to coat and cap the hollow fiber. The hollow fiber is selected from at least one of hollow carbon fiber and hollow halloysite nanotube, and the liquid is specifically heavy oil.

2. The liquid-core fiber according to claim 1, wherein: The temperature of the liquid when added is 80-120°C.

3. The liquid-core fiber according to claim 1, wherein: The epoxy resin is specifically a liquid ultraviolet-curable epoxy resin. After the epoxy resin is added, the solid is separated from the sealed container and dispersed, and then irradiated with ultraviolet light to fully cure it.

4. Low PM10 emission friction material based on liquid core fiber, characterized by: The friction material comprises, by weight, 13-33 parts of liquid-core fiber, 10-15 parts of adhesive, 15-30 parts of friction modifier, and 25-55 parts of friction filler. The liquid-core fiber is selected from any one of claims 1-3.

5. The friction material according to claim 4, wherein: The adhesive is specifically a graphene-reinforced polyimide resin, and the graphene content is 0.5wt%-1wt%, and the graphene is specifically graphene oxide with a particle size of less than 1 micron; the friction modifier is selected from at least one of stannous sulfide, graphite flakes, and nano-silicon carbide wafers; and the friction filler is selected from at least one of barium sulfate and potassium sodium hexatitanate.

6. The friction material according to claim 4, wherein: The friction material comprises, by weight, 10-15 parts of liquid-core carbon fibers, 3-8 parts of liquid-core halloysite nanotubes, 10-15 parts of graphene-reinforced polyimide resin, 5-10 parts of stannous sulfide, 5-10 parts of phosphorus flake graphite, 5-10 parts of nano-silicon carbide chips, 10-25 parts of barium sulfate, and 15-30 parts of potassium sodium hexatitanate.

7. The method for preparing the friction material according to claim 4, characterized in that The method comprises: preparing raw materials according to a formula, mixing the raw materials and then performing molding.

8. The method according to claim 7, wherein: The raw materials are mixed evenly in a high-speed mixer at a speed of 2000-5000 rpm. The temperature during molding is 135-150°C and the pressure is 200-500 kg / cm 2 The green body obtained by compression molding is placed at 145-160°C for curing.

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