CN111877050B - Preparation method of 3D-doped layered porous graphene sheet paper-based friction material - Google Patents

Abstract

The invention discloses a preparation method of a 3D-doped layered porous graphene sheet paper-based friction material, and belongs to the field of crossing of the paper industry and the material industry. The preparation method comprises the following steps: (1) Adding 3D layered porous graphene sheets in the process of papermaking of the polyether-ether-ketone fibers and the aramid pulp, wherein the adding amount of the 3D layered porous graphene sheets accounts for 0-1.0% of the mass ratio of the pulp, but is not 0; (2) Carrying out wet forming, dewatering and drying treatment on the mixed slurry to obtain raw paper of the friction material; (3) And (3) dipping the base paper in a polyimide resin solution, drying and hot-pressing to obtain the 3D-doped layered porous graphene sheet paper-based friction material. According to the invention, the 3D layered porous graphene sheet is added in the process of making paper by the polyether-ether-ketone fiber and aramid pulp, so that the paper can easily slide between layers, the resistance reducing performance is improved, the dimensional stability of the paper-based friction material is improved, and the wear resistance of the material is obviously improved.

Description

A preparation method of doped 3D layered porous graphene sheet-based friction material

technical field

The invention relates to a preparation method of a doped 3D layered porous graphene sheet paper-based friction material, which belongs to the intersection field of papermaking industry and material industry.

Background technique

Paper-based friction materials are mainly composed of fibers, binders, fillers, modifiers with friction properties, etc. Usually, paper-based friction material base paper is produced by papermaking, and then impregnated with resin to form paper-based friction materials. Paper-based friction materials have developed into a class of superior friction materials because of their advantages such as low production cost, stable dynamic friction coefficient, close dynamic/static friction coefficient ratio, stable lamination performance, low wear rate, long service life, low noise and protection of the dual material. More and more important wet friction materials that gradually replace resin-based and metal-based friction materials are applied to clutches in automotive transmission systems and brake pads in braking systems.

In order to improve the mechanical strength of the paper-based friction material and meet the high porosity of the paper-based friction material, by increasing the thermal conductivity during the friction process, the heat generated during the friction process can be taken away in time through the pores, thereby reducing the heat to the friction material. losses while improving friction performance and reducing wear rates. Conventional friction fillers such as diatomite, carbon black, and graphite are widely used in the preparation of paper-based friction materials, but their porosity is small and easy to agglomerate, which affects the performance of friction materials.

The reinforcing fiber in common paper-based friction materials is aramid fiber. Although long-term stability is the most important characteristic of aramid fiber, aramid fiber has poor UV resistance; aramid fiber itself contains amide groups, which are highly polar and easy to wear. Water absorption, when the H in the amide group is replaced by a hydrophilic group in some solvents, it will become easier to absorb water. Therefore, in aramid fiber friction materials, some aramid fibers are exposed on the upper and lower surfaces of the material, making the material have a strong water absorption capacity, so this type of material often suffers from water seepage problems due to surface layer damage and small cracks. In addition, in a low temperature environment, the water absorbed by the aramid fiber friction material will expand after being frozen, and then destroy the bond between the reinforcement and the matrix, which will greatly reduce the performance of the paper-based friction material.

Polyether ether ketone fiber (PEEK fiber) is a kind of fully aromatic fiber, and there are ether bonds and ketone bonds, and the moisture regain is only 0.1%, so that the high temperature resistance, friction resistance and corrosion resistance of the fiber are significantly higher than those of aromatic fibers. Lun fiber has extremely excellent comprehensive properties and is suitable for the molding process of traditional thermoplastics, making it an ideal material for aerospace, energy and chemical industry, transportation, food processing, medical and health and other fields. Under higher temperature conditions, PEEK fiber still has good friction and excellent self-lubricating properties, maintains outstanding wear rate and low friction coefficient; in addition, its tensile strength can be as high as 700MPa, and its modulus is 3 ~6GPa, because of its excellent friction resistance, high temperature resistance, and easy processing, it can be used in engine inner covers, automotive bearings, seals, brake pads, etc. in the automotive industry.

Because polyether ether ketone fiber has excellent properties such as friction resistance, high temperature resistance, and corrosion resistance, it has been applied in many fields, but there are still some defects. The fiber wettability is poor, and the binding force with the fiber is weak. For example, the average fiber length, fiber content, and fiber distribution in the composite material obtained by the injection molding process are poor, or the friction resistance is poor. In the prior art, by increasing the strength material to increase its performance; CN105504670A discloses the preparation of polyimide fiber-reinforced polyetheretherketone resin-based composite material, but its polyetheretherketone resin has poor wettability to polyimide fiber and weak binding force to fiber wrapping. This leads to problems such as insufficient interlayer strength of the composite material and easy falling off; CN107245898A proposes to use carbon fiber, polyether ether ketone fiber, and plant fiber to make a resin-based friction material, but the fiber is not modified and the surface of the fiber is smooth, resulting in low bonding strength; CN104927298A discloses a carbon fiber coated with polyetherimide (PEI) to strengthen the polyetheretherketone resin-based wear-resistant composite material, but due to the inert surface of its carbon fiber, PEI has a small amount of coating on its surface and is easy to agglomerate , uneven distribution on the surface of the fiber, the wear-resistant material prepared by it has poor uniformity and friction uniformity. The above existing patents have problems such as insufficient bonding force between friction fillers, fibers and resin substrates, uneven pores, etc., resulting in a decrease in the mechanical properties and friction properties of the material.

Therefore, it is necessary to develop a polyether ether ketone fiber-based composite paper-based friction material with high porosity, good thermal conductivity and excellent friction performance.

Contents of the invention

In order to solve the problems of low porosity and poor friction performance in existing patents, the present invention provides a doped 3D layered porous graphene sheet-based friction material and its preparation method. (PEEK fiber) is modified to enhance the mechanical meshing or chemical combination between the fiber and the friction filler and resin, thereby improving the mechanical strength and friction performance of the friction material; as a new type of filler, graphene has high porosity and mechanical properties. As a form of graphene, three-dimensional (3D) layered porous graphene has many excellent properties of single-layer graphene, and its unique self-supporting structure can significantly reduce the single-layer graphene. Agglomeration effect, and its internal porous, higher mechanical strength, larger specific surface area, and very good thermal conductivity, these excellent characteristics make 3D layered porous graphene in energy, materials, environment, sensing and capacitance, etc. fields are widely used. Doped with 3D layered porous graphene sheets, and using papermaking technology to prepare polyetheretherketone fiber composite paper-based friction material, the material has good friction resistance and stability, improves the porosity of the material, and retains the excellent performance of the paper-based material. High temperature resistance and mechanical properties.

The first object of the present invention is to provide a method for preparing doped 3D layered porous graphene sheet paper-based friction material, comprising the following steps:

(1) Pretreat the polyether ether ketone fiber, then mix it with aramid pulp, and then disperse it after mixing, then add dispersant, retention and drainage aid, filler, 3D layered porous graphene sheet, and stir to obtain a mixture Slurry, wherein the amount of 3D layered porous graphene sheets accounts for 0% to 1.0% of the mass of the mixed slurry, but not 0;

(2) wet-forming, dehydrating, and drying the mixed slurry obtained in step (1) to obtain friction material base paper;

(3) The base paper obtained in the step (2) is dipped in a resin solution, dried, and hot-pressed to obtain a paper-based friction material doped with 3D layered porous graphene sheets.

In one embodiment of the present invention, the added amount of the 3D layered porous graphene sheet accounts for 0.2%-0.5% of the mass of the mixed slurry.

In one embodiment of the present invention, the added amount of the 3D layered porous graphene sheet accounts for 0.3% of the mass of the mixed slurry.

In one embodiment of the present invention, the pretreatment of the polyetheretherketone fiber in step (1) is one of coupling agent modification, acid-base modification or low-temperature plasma modification.

In one embodiment of the present invention, the modification of the coupling agent is as follows: prepare a coupling agent solution with a solid content of 10% to 20%, add polyether ether ketone fiber, seal it and place it for 0.5-3.0h, and then take it out Rinse with water for 4-6 times, and finally stand in water for 0.5-2 hours, then take it out and dry at 60-90°C for 10-12 hours.

In one embodiment of the present invention, the coupling agent is Y-aminopropyltriethoxysilane (KH550), N-β(aminoethyl)-Y-aminopropyltrimethoxysilane, aniline One of the base methyl triethoxy silane.

In one embodiment of the present invention, the water is preferably deionized water.

In one embodiment of the present invention, the acid-base modification is as follows: mix polyether ether ketone fibers with 65% concentrated sulfuric acid at a mass ratio of 1:4, stir evenly, treat for 10-30 minutes, and then vacuum Remove the acid solution by filtration, wash with water until neutral, then dry at 90-110°C, and stir well.

In one embodiment of the present invention, the low-temperature plasma modification is as follows: using a low-temperature plasma apparatus to modify polyether ether ketone fibers with air as the reaction gas condition, at a temperature of 180-220°C and a relative humidity Under the condition of 65%, set and adjust the parameters to: air pressure 15-25Pa, time 3-5min, power 50W-250W, and the polyether ether ketone fiber can be treated.

In one embodiment of the present invention, the mass ratio of the polyetheretherketone fiber to the aramid pulp described in step (1) is (2-6):(8-4).

In one embodiment of the present invention, the dispersant in step (1) is one or more of polyethylene oxide, methyl cellulose or Tween; the reinforcing agent is styrene-butadiene latex, modified One or more of starch or resin glue; the retention and drainage aid is one or more of cationic polyacrylamide, chitosan or guar gum; the filler is graphite or friction modifier , wherein, the friction modifier includes one or more of barium sulfate, kaolin or diatomaceous earth.

In one embodiment of the present invention, the resin described in step (3) is polyimide resin, phenolic resin or epoxy resin; The diluting reagent that adopts in the described resin solution is N,N-dimethyl Any one of acetamide, acetone, ethanol, toluene or xylene; the concentration of the resin solution is 2wt%-20wt%.

In one embodiment of the present invention, the hot pressing in step (3) is roller hot pressing, and the process is: 280-320° C., 0.3-1.0 MPa, and vehicle speed 4-15 m/min. In one embodiment of the present invention, the preparation method is specifically:

(1) Fiber pretreatment: modify polyether ether ketone fibers by acid-base treatment, coupling agent treatment or low-temperature plasma treatment;

(2) Mix the modified polyether ether ketone fiber and aramid pulp, the mass ratio of polyetheretherketone fiber and aramid pulp is (2～6):(8～4), mix and use Fiber deflagger for 10 to 30 minutes, then add dispersant, retention and drainage aid, filler, 3D layered porous graphene sheet, and stir for 10 to 120 s to obtain a mixed slurry, wherein the dispersant, retention and drainage aid The addition of filter agent and filler accounts for 0.05% to 1% of the mass of the mixed slurry, and the addition of 3D layered porous graphene sheets accounts for 0 to 1.0% of the mass of the mixed slurry, but not 0;

(3) The above-mentioned mixed slurry is subjected to wet forming, dehydration and drying treatment to obtain a friction material base paper.

(4) The resin is diluted with a diluent to form a resin solution, the base paper is dipped in the resin solution, dried, and hot-pressed to obtain a paper-based friction material doped with 3D layered porous graphene sheets.

The second object of the present invention is the doped 3D layered porous graphene sheet paper-based friction material prepared by the method of the present invention.

The third object of the present invention is the application of the doped 3D layered porous graphene sheet paper-based friction material of the present invention in engine inner covers, automobile bearings, seals or brake pads.

Beneficial effects of the present invention:

(1) The present invention adopts the method of combining wet papermaking forming and hot pressing treatment to prepare a new type of doped 3D layered porous graphene sheet paper-based friction material, which has simple process flow, easy operation and controllable product quality Etc.

(2) The present invention chemically modifies the surface of the polyether ether ketone fiber to enhance its chemical activity and surface properties, and enhance its binding ability with resin, thereby enhancing the wear resistance and mechanical strength of the friction material.

(3) The present invention adopts the method of adding 3D layered porous graphene sheets in the slurry, and the wear resistance, mechanical properties and thermal properties are also significantly enhanced while reducing the cost.

(4) In the present invention, the modified polyether ether ketone fiber and aramid pulp are uniformly mixed and dispersed, and the friction material base paper is made by adding 3D layered porous graphene sheets and using a wet papermaking method. By impregnating in the resin solution, a paper-based friction material with enhanced friction performance is obtained, forming a three-dimensional porous network structure, which improves the friction resistance and stability, and at the same time, retains the excellent high temperature resistance, mechanical properties, and Flexibility and corrosion resistance.

Description of drawings

Figure 1 is an electron microscope image of a 3D layered porous graphene sheet.

Fig. 2 is a schematic diagram of the preparation process of the doped 3D layered porous graphene sheet-based friction material of Example 1.

Detailed ways

Test Methods:

(1) The determination method of the tensile index index is determined according to the national standard GB/T2914-2008.

(2) The determination method of the burst index is determined according to the national standard GB/T454-2002.

(3) The tear index is measured in accordance with the national standard GB/T455-2002.

(4) According to the requirements of QC/T583-1999 "Test Method for Apparent Porosity of Automobile Brake Lining", the porosity of the sample is tested by the oil absorption method, and calculated according to the formula:

In the formula: P--porosity, %;

G ₁ -- dry sample weight, g;

G ₂ -- the weight of the oil-saturated sample in the oil, g;

G ₃ -- the weight of the saturated sample in air, g.

(5) Determination of friction coefficient:

The coefficient of dynamic friction is according to the following formula

Among them: μ _d -- dynamic friction coefficient;

M _d --moment of dynamic friction, N×m

P--the load on the end face of the friction pair, N

R _CP -- sample effective radius, cm

Static friction coefficient according to the following formula

Among them: μ _j -- static friction coefficient;

M _j --Static frictional moment, N×m

P--the load on the end face of the friction pair, N

R _CP -- sample effective radius, cm

R ₁ and R ₂ are the outer and inner radii of the friction material of the sample, respectively, unit: cm.

(6) Wear rate calculation formula:

Among them: V--wear rate, cm ³ /J;

A--sample contact area, cm ² ;

Δh--the thickness difference of the friction material before and after wear, cm

n--brake clutch times

I ₀ -- the total inertia of the testing machine, kg×m ² , I ₀ is calculated by the following formula:

I ₀ =I ₁ +I ₂

I ₁ -- Inertia of the main shaft of the testing machine, I ₁ =0.035kg×m ²

I ₂ --the configuration inertia of the testing machine, I ₂ =0.2kg×m ² .

ω--Braking initial angular velocity, rad/s.

Example 1

A preparation method of a doped 3D layered porous graphene sheet paper-based friction material, as shown in Figure 2, comprising the following steps:

(1) Coupling agent modified pretreatment polyether ether ketone fiber: Prepare a coupling agent KH550 solution with a solid content of 20%, add polyether ether ketone fiber, seal the beaker with plastic wrap, place it in a fume hood for 1.5h, polyether After the ether ketone fiber is treated, take it out, wash it twice with tap water, and finally let it stand in water for 0.5h, then put it into an electric heating constant temperature drum drying oven at 80°C for 12h, and put it in a sample bag for storage;

(2) Mix the treated polyetheretherketone fiber and aramid pulp, and add 3D layered porous graphene sheets to the pulp, wherein the amount of 3D layered porous graphene sheets accounts for 0.3% of the mass of the mixed pulp , and then use the method of wet papermaking to prepare friction material base paper;

(3) Use N,N-dimethylacetamide solution to configure a polyimide resin solution with a concentration of 10%, stir at a high speed, and disperse evenly; fully impregnate the friction material base paper in the polyimide resin solution, and then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290 °C, the pressure is 0.8 MPa, and the speed is 5 m/min, that is, the doped 3D layered porous graphene sheet paper-based friction material is obtained.

Example 2

A preparation method of a doped 3D layered porous graphene sheet paper-based friction material, comprising the following steps:

(1) Coupling agent modified pretreatment polyether ether ketone fiber: Prepare a coupling agent KH550 solution with a solid content of 20%, add polyether ether ketone fiber, seal the beaker with plastic wrap, place it in a fume hood for 1.5h, polyether After the ether ketone fiber is treated, take it out, wash it twice with tap water, and finally let it stand in water for 0.5h, then put it into an electric heating constant temperature drum drying oven at 80°C for 12h, and put it in a sample bag for storage;

(2) Mix the treated polyetheretherketone fiber and aramid pulp, and add 3D layered porous graphene sheets in the pulp, wherein the amount of 3D layered porous graphene sheets accounts for 0.2% of the mass of the mixed pulp , and then use the method of wet papermaking to prepare friction material base paper;

(3) Use N,N-dimethylacetamide solution to configure a polyimide resin solution with a concentration of 10%, stir at a high speed, and disperse evenly; fully impregnate the friction material base paper in the polyimide resin solution, and then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290 °C, the pressure is 0.8 MPa, and the speed is 5 m/min, that is, the doped 3D layered porous graphene sheet paper-based friction material is obtained.

Example 3

A preparation method of a doped 3D layered porous graphene sheet paper-based friction material, comprising the following steps:

(1) Coupling agent modified pretreatment polyether ether ketone fiber: Prepare a coupling agent KH550 solution with a solid content of 20%, add polyether ether ketone fiber, seal the beaker with plastic wrap, place it in a fume hood for 1.5h, polyether After the ether ketone fiber is treated, take it out, wash it twice with tap water, and finally let it stand in water for 0.5h, then put it into an electric heating constant temperature drum drying oven at 80°C for 12h, and put it in a sample bag for storage;

(2) Mix the treated polyetheretherketone fiber and aramid pulp, and add 3D layered porous graphene sheets to the pulp, wherein the amount of 3D layered porous graphene sheets accounts for 0.4% of the mass of the mixed pulp , and then use the method of wet papermaking to prepare friction material base paper;

(3) Use N,N-dimethylacetamide solution to configure a polyimide resin solution with a concentration of 10%, stir at a high speed, and disperse evenly; fully impregnate the friction material base paper in the polyimide resin solution, and then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290 °C, the pressure is 0.8 MPa, and the speed is 5 m/min, that is, the doped 3D layered porous graphene sheet paper-based friction material is obtained.

Example 4

A preparation method of a doped 3D layered porous graphene sheet paper-based friction material, comprising the following steps:

(1) Coupling agent modified pretreatment polyether ether ketone fiber: Prepare a coupling agent KH550 solution with a solid content of 20%, add polyether ether ketone fiber, seal the beaker with plastic wrap, place it in a fume hood for 1.5h, polyether After the ether ketone fiber is treated, take it out, wash it twice with tap water, and finally let it stand in water for 0.5h, then put it into an electric heating constant temperature drum drying oven at 80°C for 12h, and put it in a sample bag for storage;

(2) Mix the treated polyetheretherketone fiber and aramid pulp, and add 3D layered porous graphene sheets to the pulp, wherein the amount of 3D layered porous graphene sheets accounts for 0.5% of the mass of the mixed pulp , and then use the method of wet papermaking to prepare friction material base paper;

(3) Use N,N-dimethylacetamide solution to configure a polyimide resin solution with a concentration of 10%, stir at a high speed, and disperse evenly; fully impregnate the friction material base paper in the polyimide resin solution, and then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290 °C, the pressure is 0.8 MPa, and the speed is 5 m/min, that is, the doped 3D layered porous graphene sheet paper-based friction material is obtained.

Comparative example 1

A preparation method of an undoped 3D layered porous graphene sheet paper-based friction material, comprising the following steps:

(1) Coupling agent modified pretreatment polyether ether ketone fiber: Prepare a coupling agent KH550 solution with a solid content of 20%, add polyether ether ketone fiber, seal the beaker with plastic wrap, place it in a fume hood for 1.5h, polyether After the ether ketone fiber is treated, take it out, wash it twice with tap water, and finally let it stand in water for 0.5h, then put it into an electric heating constant temperature drum drying oven at 80°C for 12h, and put it in a sample bag for storage;

(2) Mix the treated polyetheretherketone fiber and aramid pulp, and prepare the friction material base paper by wet method;

(3) use N, N-dimethylacetamide solution configuration concentration to be the polyimide resin solution of 10wt%, high-speed stirring, make uniform dispersion; The friction material base paper is fully impregnated in the polyimide resin solution, then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290°C, the pressure is 0.8 MPa, and the vehicle speed is 5m/min, that is, the non-doped 3D layered porous graphene sheet paper-based friction material is obtained.

Comparative example 2

A preparation method of an undoped 3D layered porous graphene sheet paper-based friction material, comprising the following steps:

(1) Acid-base modification pretreatment of polyetheretherketone fiber: mix polyetheretherketone fiber with 65% concentrated sulfuric acid in a mass ratio of 1:4, stir evenly, treat for 30 minutes, and then vacuum filter to remove the acid solution. Wash with deionized water until neutral, then dry at 105°C, stir evenly, and set aside;

(2) Mix the treated polyetheretherketone fiber and aramid pulp, and prepare the friction material base paper by wet method;

(3) Use N,N-dimethylacetamide solution to configure a polyimide resin solution with a concentration of 10%, stir at a high speed, and disperse evenly; fully impregnate the friction material base paper in the polyimide resin solution, and then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290°C, the pressure is 0.8 MPa, and the vehicle speed is 5m/min, that is, the non-doped 3D layered porous graphene sheet paper-based friction material is obtained.

Comparative example 3

A preparation method of an undoped 3D layered porous graphene sheet paper-based friction material, comprising the following steps:

(1) Modification at low-temperature plasma: Use low-temperature plasma instrument to modify polyetheretherketone fibers with air as the reaction gas. Under the conditions of temperature 200°C and relative humidity 65%, set and adjust parameters to : The air pressure is 20Pa, the time is 3min, the power is 100W, and the sample is processed for use;

(2) Mix the treated polyetheretherketone fiber and aramid pulp, and prepare the friction material base paper by wet method;

(3) Use N,N-dimethylacetamide solution to prepare a polyimide resin solution with a concentration of 5%, stir at a high speed, and disperse evenly; fully immerse the poly friction material base paper in the polyimide resin solution, Then, it is dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290°C, the pressure is 0.8 MPa, and the vehicle speed is 5m/min, so as to obtain an undoped 3D layered porous graphene sheet paper-based friction material.

Example 5

A preparation method of a doped 3D layered porous graphene sheet paper-based friction material, comprising the following steps:

(1) Coupling agent modified pretreatment polyether ether ketone fiber: Prepare a coupling agent KH550 solution with a solid content of 20%, add polyether ether ketone fiber, seal the beaker with plastic wrap, place it in a fume hood for 1.5h, polyether After the ether ketone fiber is treated, take it out, wash it twice with tap water, and finally let it stand in water for 0.5h, then put it into an electric heating constant temperature drum drying oven at 80°C for 12h, and put it in a sample bag for storage;

(2) Mix the treated polyetheretherketone fiber and aramid pulp, and add 3D layered porous graphene sheets into the pulp, wherein the amount of 3D layered porous graphene sheets accounts for 0.1% of the mass of the mixed pulp , and then use the method of wet papermaking to prepare friction material base paper;

(3) Use N,N-dimethylacetamide solution to configure a polyimide resin solution with a concentration of 10%, stir at a high speed, and disperse evenly; fully impregnate the friction material base paper in the polyimide resin solution, and then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290 °C, the pressure is 0.8 MPa, and the speed is 5 m/min, that is, the doped 3D layered porous graphene sheet paper-based friction material is obtained.

Comparative example 4

A method for preparing a diatomite-doped paper-based friction material, comprising the following steps:

(1) Coupling agent modified pretreatment polyether ether ketone fiber: Prepare a coupling agent KH550 solution with a solid content of 20%, add polyether ether ketone fiber, seal the beaker with plastic wrap, place it in a fume hood for 1.5h, polyether After the ether ketone fiber is treated, take it out, wash it twice with tap water, and finally let it stand in water for 0.5h, then put it into an electric heating constant temperature drum drying oven at 80°C for 12h, and put it in a sample bag for storage;

(2) Mix the treated polyether ether ketone fiber and aramid pulp, add diatomite powder into the pulp, wherein the amount of diatomite added accounts for 0.3% of the mass of the mixed pulp, and then use the wet method to make Method for preparing friction material base paper;

(3) Use N,N-dimethylacetamide solution to configure a polyimide resin solution with a concentration of 10%, stir at a high speed, and disperse evenly; fully impregnate the friction material base paper in the polyimide resin solution, and then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290°C, the pressure is 0.8 MPa, and the vehicle speed is 5m/min, that is, the doped diatomite paper-based friction material is obtained.

Comparative example 5

A preparation method of doped graphite paper-based friction material, comprising the following steps:

(1) Coupling agent modified pretreatment polyether ether ketone fiber: Prepare a coupling agent KH550 solution with a solid content of 20%, add polyether ether ketone fiber, seal the beaker with plastic wrap, place it in a fume hood for 1.5h, polyether After the ether ketone fiber is treated, take it out, wash it twice with tap water, and finally let it stand in water for 0.5h, then put it into an electric heating constant temperature drum drying oven at 80°C for 12h, and put it in a sample bag for storage;

(2) Mix the treated polyether ether ketone fiber and aramid pulp, add graphite powder into the pulp, wherein, the amount of graphite added accounts for 0.3% of the mass of the mixed pulp, and then use the method of wet papermaking to prepare friction powder material base paper;

(3) Use N,N-dimethylacetamide solution to configure a polyimide resin solution with a concentration of 10%, stir at a high speed, and disperse evenly; fully impregnate the friction material base paper in the polyimide resin solution, and then , dried and hot-pressed. The hot-pressing process is as follows: the temperature is 290°C, the pressure is 0.8 MPa, and the vehicle speed is 5m/min, that is, the doped graphite paper-based friction material is obtained.

According to the methods of Examples 1-5 and Comparative Examples 1-5, the properties of the (non-)doped 3D layered porous graphene sheet paper-based friction material prepared are shown in Table 1 below, and Examples 1-5 are doped Different concentrations of 3D layered porous graphene sheet paper-based friction material, when the concentration is 0.3%, the performance of the paper-based friction material is the best. When the doping concentration is too high, the friction performance may decrease due to the uneven dispersion of graphene. Comparative examples 1 to 3 show that different modification methods have different effects on the performance of friction materials, among which the modification of amino coupling agent improves the performance of non-doped 3D layered porous graphene sheet-based paper-based friction materials most obviously.

Table 1 Performance test data of the (non-)doped 3D layered porous graphene sheet paper-based friction material prepared in Examples and Comparative Examples

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with this technology can make various changes and modifications without departing from the technology and scope of the present invention. Therefore The scope of protection of the present invention should be defined by the claims.

Claims (7)

1. A preparation method of a 3D-doped layered porous graphene sheet paper-based friction material is characterized by comprising the following steps:

(1) Pretreating polyether-ether-ketone fibers, mixing the pretreated polyether-ether-ketone fibers with aramid pulp, defibering the mixture, adding a dispersing agent, a retention and filtration aid, a filler and a 3D layered porous graphene sheet, and stirring the mixture to obtain mixed slurry, wherein the addition amount of the 3D layered porous graphene sheet accounts for 0.3% of the mass of the mixed slurry;

(2) Carrying out wet forming, dewatering and drying treatment on the mixed slurry obtained in the step (1) to obtain raw paper of the friction material;

(3) Dipping the base paper obtained in the step (2) in a resin solution, drying and hot-pressing to obtain a 3D-doped layered porous graphene sheet paper-based friction material;

the pretreatment of the polyether-ether-ketone fiber in the step (1) is one of coupling agent modification, acid-base modification or low-temperature plasma modification;

the mass ratio of the polyether-ether-ketone fibers to the aramid pulp in the step (1) is (2~6): (8~4).

2. The method according to claim 1, wherein the coupling agent is one of silane coupling agents KH550, KH560, KH570 and KH 792.

3. The method of claim 1, wherein the acid-base modification is performed by using an acid-base modifier, and the acid-base modifier is one of sulfuric acid, nitric acid and NaOH.

4. The method of claim 1, wherein the coating gas used in the low temperature plasma modification is N ₂ 、O ₂ And one of the air, the power is 50W to 400W.

5. The method according to claim 1, wherein the hot pressing in step (3) is a roller type hot pressing, and the process is as follows: 280-320 ℃, 0.3-1.0 MPa and 4-15m/min of vehicle speed.

6. The doped 3D layered porous graphene sheet paper-based friction material prepared by the method of any one of claims 1 to 5.

7. The use of the doped 3D layered porous graphene sheet paper-based friction material of claim 6 in an engine inner cover, an automobile bearing, a seal or a brake pad.

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