CN106868902B - A kind of preparation method of sheet self assembly manganese dioxide modified carbon fiber reinforced resin base frication material - Google Patents

Abstract

The invention discloses a kind of preparation methods of sheet self assembly manganese dioxide modified carbon fiber reinforced resin base frication material, carbon fiber is pre-processed using acid solution oxidizing process, then utilize redox reaction in carbon fiber surface growth in situ sheet self assembly manganese dioxide using potassium permanganate and the concentrated sulfuric acid, and it is with large specific surface area, easily and many advantages, such as resin-bonded, as friction material reinforcement, applied to wet type resin-matrix friction material, can effectively increased fiber and resin-bonded specific surface area, and then improve the interfacial combined function of carbon fiber and matrix, make friction material that there is more excellent friction and wear behavior.

Description

A sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction material Preparation

technical field

The invention belongs to the field of wet friction materials, and in particular relates to a preparation method of sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction materials.

Background technique

Resin-based friction material is a multi-component composite material that is hot-pressed after being fully mixed with binder (resin), reinforcing fiber and friction performance regulator. It has excellent friction and wear performance, simple preparation process and designable performance. With the advantages of strong performance and low cost, its application is becoming more and more widespread.

The Chinese patent with the application number CN103450501A "A Method for Surface Modification of Carbon Fiber Using Potassium Persulfate/Silver Nitrate System" puts the carbon fiber into the extraction tube of the Soxhlet extractor, and uses acetone as the extraction agent to perform Soxhlet extraction to remove impurities, namely Condensation and reflux reaction at a temperature of 75-85°C for 4h-8h to obtain carbon fibers after removing surface impurities, and place the carbon fibers after cleaning with acetone in a supercritical acetone-water system with a temperature of 350-380°C and a pressure of 7-15MPa Soak for 15 to 30 minutes to remove the epoxy coating of carbon fiber. Although this method can remove the epoxy coating very well, it requires high experimental conditions and is not conducive to engineering applications.

The Chinese patent "a carbon fiber surface modification method" with the application number CN104195824A uses acetone at 60-100°C to remove the sizing agent and impurities on the surface of the carbon fiber. After cleaning and drying, the carbon fiber is placed in a round bottom flask , add concentrated acid, oxidize at 60-80°C for 2-5 hours, soak the oxidized carbon fibers in distilled water for 5-10 minutes, then take out the carbon fibers soaked in distilled water, discard the distilled water, repeat the above steps 5-10 10 times to get the pre-treated carbon fiber. This method requires many repeated steps during the experiment, which is tedious and time-consuming.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction material, to overcome the above-mentioned defects in the prior art. The final carbon fiber is used as a fiber reinforcement to prepare a resin-based friction material with the characteristics of high friction coefficient and low wear.

To achieve the above object, the present invention adopts the following technical solutions:

A method for preparing sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction material, comprising the following steps:

Step 1: Soak the carbon fiber in acetone solution, after removing the carbon fiber sizing agent, wash the carbon fiber repeatedly until neutral and dry;

Step 2: Mix the carbon fiber dried in step 1 with concentrated nitric acid to obtain a carbon fiber mixed system, heat the carbon fiber mixed system to 80-90°C and react for 2-4 hours, cool to room temperature after the reaction is completed, and alternately alternate the carbon fiber with deionized water and ethanol Wash until the solution is neutral and dry;

Step 3: Mix and grind the carbon fiber obtained in Step 2 with solid potassium permanganate, put the mixture into distilled water and stir, then add concentrated sulfuric acid and stir, then heat the obtained mixed solution to obtain flaky self-assembled manganese dioxide Modified carbon fiber rough product, the modified carbon fiber rough product is obtained by repeatedly washing to neutrality and drying;

Step 4: Disperse modified carbon fiber, aramid fiber, and paper fiber in water by wet pulping process, and then use papermaking molding process to prepare fiber reinforced material;

Step five: impregnating the fiber reinforced material with the modified phenolic resin and curing by hot pressing to obtain the resin-based friction material.

Further, in the first step, the carbon fiber is soaked in acetone solution for 36-48 hours.

Further, in step 2, carbon fiber and concentrated nitric acid are mixed at a mass ratio of 1:50 to obtain a carbon fiber mixed system.

Further, the mass ratio of carbon fiber and potassium permanganate in step 3 is 1:10; in step 3, carbon fiber and potassium permanganate are mixed and ground in a mortar for 8-15 minutes.

Further, in step 3, put the ground mixture into distilled water and stir for 10 hours, then add concentrated sulfuric acid dropwise and stir for 1 hour, wherein 2.2g of the mixture is added to every 200mL of distilled water, and 0.5-1.5mL of concentrated sulfuric acid.

Further, in step 3, the mixed solution is heated at a temperature of 80-160° C. for 2-6 hours to obtain a crude product of sheet-like self-assembled manganese dioxide modified carbon fiber.

Further, in step 4, the modified carbon fiber, aramid fiber, and paper fiber are dispersed in water according to the mass ratio of (9-13):(2-3):(2-3), and then prepared by papermaking molding process Fiber reinforcement.

Further, the mass ratio of the modified phenolic resin to the modified carbon fiber in step five is (6-8):(3-5).

Further, in Step 5, the hot-press curing temperature is 150-180° C., the time is 8-15 minutes, and the pressure is 5-10 MPa.

Further, the carbon fiber in step 1 is polyacrylonitrile-based carbon fiber or pitch-based carbon fiber; the paper fiber in step 4 is wood fiber or bamboo fiber; the aramid fiber is chopped aramid fiber, precipitated aramid fiber or aramid pulp Meal.

Compared with the prior art, the present invention has the following beneficial technical effects:

In the present invention, the acid solution oxidation method is used to pretreat the carbon fiber, and then potassium permanganate and concentrated sulfuric acid are used to grow sheet-like self-assembled manganese dioxide in situ on the surface of the carbon fiber by redox reaction, and it has a large specific surface area and is easy to combine with Resin bonding and many other advantages, using it as a friction material reinforcement, applied to wet resin-based friction materials, can effectively increase the specific surface area of fiber and resin bonding, and then improve the interfacial bonding performance between carbon fiber and matrix, so that the friction material has more Excellent friction and wear properties.

Further, by controlling the conditions, the method of the present invention reduces the wear rate of the resin-based friction material prepared from carbon fibers modified by sheet-like self-assembled manganese dioxide to about 1/9 of that of the resin-based friction material prepared from original carbon fibers. The resin-based friction material has excellent friction and wear performance. According to the technical standard of GB/T 13826-2008, its dynamic friction coefficient reaches 0.09-0.16, and the friction material wear rate is 1.88×10 ^-9 cm ³ /J～1.62×10 ^{- 8} cm ³ /J, showing excellent friction and wear properties and wear resistance.

Description of drawings

Figure 1 is an SEM image of sheet-like self-assembled manganese dioxide grown on the surface of carbon fibers, wherein a is an SEM image magnified 5k times; b is an SEM image magnified 50k times;

Figure 2 is a comparison of the wear rate of the resin-based friction material prepared with sheet-like self-assembled manganese dioxide modified carbon fiber and the resin-based friction material prepared with original carbon fiber, where CF0: original carbon fiber reinforced resin-based friction material; CF1: sheet-like self-assembled Assembly of manganese dioxide modified carbon fiber reinforced resin-based friction material.

Detailed ways

The present invention is described in further detail below:

A method for preparing sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction material, comprising the following steps:

Step 1: Soak carbon fibers (polyacrylonitrile-based carbon fibers or pitch-based carbon fibers) with a length of 0.1-10 mm in acetone solution for 36-48 hours. Dry at ℃ for 12 to 24 hours;

Step 2: Mix the carbon fiber dried in step 1 with concentrated nitric acid at a mass ratio of 1:50 to obtain a carbon fiber mixed system, heat the carbon fiber mixed system to 80-90°C for 2-4 hours, cool to room temperature after the reaction is completed, and use the carbon fiber Wash with deionized water and ethanol alternately for 3 to 5 times until the solution is neutral and dry at 60-80°C for 12-24 hours;

Step 3: Mix and grind the carbon fiber obtained in Step 2 and solid potassium permanganate at a mass ratio of 1:10 for 8 to 15 minutes, put the mixture in distilled water and stir for 10 hours, then add concentrated sulfuric acid and stir for 1 hour. Add 2.2g of the mixture to distilled water, add 0.5-1.5mL of concentrated sulfuric acid to every 200mL of distilled water, and heat the resulting mixed solution at a temperature of 80-160°C for 2-6 hours to obtain sheet-like self-assembled manganese dioxide-modified carbon fibers The crude product, the modified carbon fiber crude product is repeatedly washed to neutrality and dried at 60-80°C for 12-24 hours to obtain the modified carbon fiber;

Step 4: Use wet pulping process to mix modified carbon fiber, aramid fiber (chopped aramid fiber, precipitated aramid fiber or aramid pulp), paper fiber (wood fiber or bamboo fiber) according to (9-13 ): (2~3): The mass ratio of (2~3) is dispersed in water, and then the fiber reinforced material is made by papermaking molding process;

Step 5: After impregnating the fiber reinforced material with modified phenolic resin, heat-press curing for 8-15 minutes at a temperature of 150-180°C and a pressure of 5-10 MPa. Among them, the mass of the modified phenolic resin and the modified carbon fiber The ratio is (6~8):(3~5), and the resin-based friction material is obtained.

Below in conjunction with embodiment the present invention is described in further detail:

Example 1

Step 1: Soak polyacrylonitrile-based carbon fibers with a length of 0.1-10 mm in acetone at room temperature for 48 hours to remove sizing agents and impurities on the surface of carbon fibers, and repeatedly wash the carbon fibers until the pH is 7 and dry them;

Step 2: Weigh 2g of the dried carbon fiber in step 1, put it into a round bottom flask, add 100g of concentrated nitric acid, and react at 90°C for 2 hours. After the reaction is completed, cool to room temperature and wash the carbon fiber alternately with deionized water and ethanol for 3 times each. to neutral and tumble dry;

Step 3: Weigh 0.2g of the carbon fiber in step 2, and weigh 2g of potassium permanganate, put the two into a mortar and grind for 10min, put the ground mixture into a beaker with 200mL of distilled water and stir 10h, then add 1mL of concentrated sulfuric acid dropwise and stir for 1h, transfer the reacted solution to a 1000mL volumetric flask, and heat at 120°C for a reaction time of 4h to obtain sheet-like self-assembled manganese dioxide modified The modified carbon fiber rough product is repeatedly washed to neutrality and dried to obtain the modified carbon fiber;

Step 4: Disperse modified carbon fiber, chopped aramid fiber, and wood fiber in water at a mass ratio of 3:1:1 by wet pulping process, and then use papermaking molding process to prepare a fiber reinforced material with a diameter of 30mm ;

Step 5: After impregnating the fiber reinforced material with modified phenolic resin, use a vulcanizer to heat press and cure for 10 minutes at a temperature of 170°C and a pressure of 5 MPa to obtain a sheet-shaped self-assembled manganese dioxide reinforced resin-based friction material, in which the modified The mass ratio of phenolic resin to modified carbon fiber was 8:5, and the sheet-like self-assembled manganese dioxide reinforced resin-based friction material was obtained.

Fig. 1 is the SEM photo of the surface of the flaky self-assembled manganese dioxide modified carbon fiber sample prepared in this example. It can be seen from the figure that a large number of flaky self-assembled manganese dioxide particles appear on the surface of the fiber, thereby increasing the surface area of the carbon fiber and increasing the surface area. The activity is improved. Figure 2 is a comparison of the wear rate of the resin-based friction material prepared by the original carbon fiber and the resin-based friction material prepared by the sheet-like self-assembled manganese dioxide modified carbon fiber. It can be seen from the figure that the modified carbon fiber reinforced sample The wear rate is 1.88×10 ^-9 cm ³ /J, which is greatly reduced to 1/9 of the original carbon fiber, showing the good combination of fiber and matrix and its wear resistance.

Example 2

Step 1: Soak the pitch-based carbon fiber with a length of 0.1-10 mm in acetone at room temperature for 36 hours to remove the sizing agent and impurities on the surface of the carbon fiber, wash the carbon fiber repeatedly until the pH is 7, and dry it;

Step 2: Weigh 2 g of the dried carbon fiber in step 1 and put it into a round bottom flask, add 100 g of concentrated nitric acid, and react at 80°C for 4 hours. After the reaction is completed, cool to room temperature and wash the carbon fiber alternately with deionized water and ethanol 4 times each. to neutral and tumble dry;

Step 3: Weigh 0.2g of the carbon fiber in step 2, and weigh 2g of potassium permanganate, put the two into a mortar and grind for 8min, put the ground mixture into a beaker with 200mL of distilled water and stir 10h, then add 0.5mL of concentrated sulfuric acid dropwise and stir for 1h, transfer the reacted solution to a 1000mL volumetric flask, heat at 80°C, and the reaction time is 2h to obtain sheet-like self-assembled manganese dioxide Modified carbon fiber rough product, the modified carbon fiber rough product is obtained by repeatedly washing to neutrality and drying;

Step 4: Disperse modified carbon fiber, precipitated aramid fiber, and bamboo fiber in water at a mass ratio of 13:2:2 by wet pulping process, and then use papermaking molding process to prepare a fiber reinforced material with a diameter of 30mm ;

Step 5: After impregnating the fiber reinforced material with modified phenolic resin, use a vulcanizer to heat press and cure for 15 minutes at a temperature of 180°C and a pressure of 8 MPa to obtain a sheet-like self-assembled manganese dioxide reinforced resin-based friction material, in which the modified The mass ratio of phenolic resin to modified carbon fiber was 6:3, and the dynamic friction coefficient of the obtained sheet-like self-assembled manganese dioxide reinforced resin-based friction material was 0.12, and the wear rate was 1.88×10 ^-9 cm ³ /J.

Example 3

Step 1: Soak the pitch-based carbon fiber with a length of 0.1-10 mm in acetone for 48 hours at room temperature to remove the sizing agent and impurities on the surface of the carbon fiber, wash the carbon fiber repeatedly until the pH is 7, and dry it;

Step 2: Weigh 2g of the dried carbon fiber in step 1, put it into a round bottom flask, add 100g of concentrated nitric acid, and react at 90°C for 2 hours. After the reaction is completed, cool to room temperature and wash the carbon fiber alternately with deionized water and ethanol for 3 times each. to neutral and tumble dry;

Step 3: Weigh 0.2g of the carbon fiber in step 2, and weigh 2g of potassium permanganate, put the two into a mortar and grind for 10min, put the ground mixture into a beaker with 200mL of distilled water and stir 10h, then add 1mL of concentrated sulfuric acid dropwise and stir for 1h, transfer the reacted solution to a 1000mL volumetric flask, and heat at 120°C for a reaction time of 6h to obtain sheet-like self-assembled manganese dioxide modified The modified carbon fiber rough product is repeatedly washed to neutrality and dried to obtain the modified carbon fiber;

Step 4: Disperse modified carbon fiber, aramid pulp, and wood fiber in water at a mass ratio of 9:2:2 by wet pulping process, and then use papermaking molding process to prepare a fiber reinforced material with a diameter of 30 mm;

Step 5: After impregnating the fiber reinforced material with modified phenolic resin, use a vulcanizer to cure it by hot pressing at 150°C and 10 MPa for 10 minutes to obtain a sheet-shaped self-assembled manganese dioxide reinforced resin-based friction material, in which the modified The mass ratio of phenolic resin to modified carbon fiber was 8:5, and the kinetic friction coefficient of the sheet-like self-assembled manganese dioxide reinforced resin-based friction material was 0.13, and the wear rate was 5.73×10 ^-9 cm ³ /J.

Example 4

Step 1: Soak polyacrylonitrile-based carbon fibers with a length of 0.1-10 mm in acetone at room temperature for 42 hours to remove sizing agents and impurities on the surface of carbon fibers, and repeatedly wash the carbon fibers until the pH is 7 and dry them;

Step 2: Weigh 2g of the dried carbon fiber in step 1 and put it into a round-bottomed flask, add 100g of concentrated nitric acid, react at 85°C for 3 hours, cool to room temperature after the reaction is completed, and wash the carbon fiber alternately with deionized water and ethanol 5 times each to neutral and tumble dry;

Step 3: Weigh 0.2g of the carbon fiber in step 2, and weigh 2g of potassium permanganate, put the two into a mortar and grind for 15min, put the ground mixture into a beaker with 200mL of distilled water and stir 10h, then add 1.5mL of concentrated sulfuric acid dropwise and stir for 1h, transfer the reacted solution to a 1000mL volumetric flask, and heat at 160°C for 4h to obtain flaky self-assembled manganese dioxide Modified carbon fiber rough product, the modified carbon fiber rough product is obtained by repeatedly washing to neutrality and drying;

Step 4: Disperse modified carbon fiber, chopped aramid fiber, and bamboo fiber in water at a mass ratio of 13:3:3 by wet pulping process, and then use papermaking molding process to prepare a fiber reinforced material with a diameter of 30mm ;

Step 5: After impregnating the fiber reinforced material with modified phenolic resin, use a vulcanizer to heat press and cure for 8 minutes at a temperature of 160°C and a pressure of 10 MPa to obtain a sheet-shaped self-assembled manganese dioxide reinforced resin-based friction material, in which the modified The mass ratio of phenolic resin to modified carbon fiber is 7:4, and the dynamic friction coefficient of the obtained sheet-like self-assembled manganese dioxide reinforced resin-based friction material is 0.11, and the wear rate is 4.10×10 ^-9 cm ³ /J.

Claims (6)

1. A method for preparing a sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction material, comprising the following steps: Step 1: Soak the carbon fiber in acetone solution, after removing the carbon fiber sizing agent, wash the carbon fiber repeatedly until neutral and dry; Step 2: Mix the carbon fiber dried in step 1 with concentrated nitric acid at a mass ratio of 1:50 to obtain a carbon fiber mixed system, heat the carbon fiber mixed system to 80-90°C for 2-4 hours, cool to room temperature after the reaction is completed, and use the carbon fiber Wash with deionized water and ethanol repeatedly and alternately until the solution is neutral and dry; Step 3: Mix and grind the carbon fiber obtained in step 2 with solid potassium permanganate, and the mass ratio of carbon fiber to potassium permanganate is 1:10, put the ground mixture into distilled water and stir for 10 hours, and then add After the concentrated sulfuric acid was stirred for 1 hour, 2.2 g of the mixture was added to every 200 mL of distilled water, and 0.5 to 1.5 mL of concentrated sulfuric acid was added to every 200 mL of distilled water, and then the obtained mixed solution was heated at a temperature of 80 to 160°C for 2 to 6 hours to obtain Sheet-shaped self-assembled manganese dioxide modified carbon fiber crude product, the modified carbon fiber crude product is repeatedly washed to neutral and dried to obtain the modified carbon fiber; Step 4: Use wet pulping process to disperse modified carbon fiber, aramid fiber, and paper fiber in water according to the mass ratio of (9~13):(2~3):(2~3), and then use papermaking to form process to produce fiber reinforced materials; Step five: impregnating the fiber reinforced material with the modified phenolic resin and curing by hot pressing to obtain the resin-based friction material. 2. The preparation method of a sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction material according to claim 1, characterized in that in step 1, the carbon fiber is soaked in acetone solution for 36-48 hours. 3. The preparation method of a kind of sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction material according to claim 1, characterized in that, in step 3, carbon fiber and potassium permanganate are mixed in a mortar and ground 8 ~ 15min. 4. the preparation method of a kind of sheet-like self-assembled manganese dioxide modified carbon fiber reinforced resin-based friction material according to claim 1, is characterized in that, in the step 5, the mass ratio of modified phenolic resin and modified carbon fiber is ( 6~8): (3~5). 5. The preparation method of a sheet-like self-assembled manganese dioxide modified carbon fiber-reinforced resin-based friction material according to claim 1, characterized in that, in step 5, the hot-press curing temperature is 150-180°C, and the time is 8 ～15min, the pressure is 5～10MPa. 6. The preparation method of a kind of sheet-like self-assembled manganese dioxide modified carbon fiber-reinforced resin-based friction material according to claim 1, wherein the carbon fiber in step 1 is polyacrylonitrile-based carbon fiber or pitch-based carbon fiber; step The paper fiber in 4 is wood fiber or bamboo fiber; the aramid fiber is chopped aramid fiber, precipitated aramid fiber or aramid pulp.