A short carbon fiber reinforced wood-epoxy resin type paper-based friction plate and its preparation method

Abstract

The present invention discloses a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate and a preparation method thereof. The preparation method includes: Step 1: Prepare functionalized short carbon fibers; Step 2: Prepare an aqueous dispersion with a wood cellulose mass fraction of 15-20 wt%; Step 3: Disperse 10 g of waterborne epoxy resin and 5-10 g of sodium lignosulfonate successively in 50-100 mL of an alkaline aqueous solution with a concentration of 1.0 mol / L, then mix with 50-100 mL of the wood cellulose dispersion prepared in Step 2, and add 3-8 g of the sucrose-functionalized short carbon fibers prepared in Step 1. After continuous stirring for 2-5 hours, a precursor dispersion is obtained. Through casting molding and high-temperature curing, demolding and cutting, a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate is obtained, which has excellent antifriction performance, low wear rate, excellent water stability, good mechanical properties, weather resistance and recyclability.

Description

Technical Field

[0001] The present invention belongs to the technical field of friction materials, and particularly relates to a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate and a preparation method thereof. Background Art

[0002] Paper-based friction materials are key components applied in power machinery for braking or transmission functions in a wet environment (oil lubrication). Paper-based wet friction materials mainly consist of fibers, fillers, friction property regulators, and adhesives, and their surface topography. The original paper is prepared by traditional papermaking processes, where fibers, fillers, and friction property regulators are dispersed in an aqueous medium and finally formed by dehydration. The material variety, material properties, and preparation processes determine the safety and stability of vehicle operation. Since it is formed by papermaking processes with fibers as the basic framework material, it is called "paper-based friction material". The introduction of asbestos fibers has greatly improved the performance of paper-based friction materials and correspondingly increased the cost performance, which is an important milestone in the development process of paper-based friction materials. Due to the carcinogenic risk of asbestos fibers, non-asbestos fiber paper-based friction materials have been widely studied.

[0003] With the pursuit of material lightweight and excellent performance in various industries, carbon fibers and their composites are increasingly widely used. The interface between carbon fibers and polymer matrices is one of the important factors determining the performance of composites, and the interface strength between the two has always been the bottleneck in improving the performance of composites. Good wetting between fibers and resin matrices is a prerequisite for forming excellent interfaces, and good mechanical meshing, chemical bonding, and other interactions are guarantees for improving the interface strength of composites. Due to the extremely small diameter of carbon fibers, the use of surface activation technology has limited improvement on their interface bonding strength. Therefore, other modification methods must be adopted, such as growing zinc oxide nanosheets, MOF metal transition layers, titanium dioxide nanorods, manganese dioxide nanoparticles, and other micro-nano reinforcement structures on the surface of carbon fibers, which can effectively promote the interface bonding strength between carbon fiber reinforcements and resin matrices. However, this traditional resin-based composite material shows obvious defects during use. First, its matrix materials are usually various thermosetting resins from the petrochemical industry, which will generate a large amount of greenhouse gases during preparation; second, the use of a large amount of phenolic resin adhesives makes it difficult to find suitable treatment methods for its waste, and the treatment cost of aldehyde substances is high, requiring a large amount of energy and funds. Therefore, there is an urgent need for new preparation technologies or alternative methods to fill the gap of resin-based composites in the field of sustainable development.

[0004] The mechanical strength of wood-based composites can be effectively enhanced by the hydrogen bond coupling between biomass macromolecules. Using biomass materials to replace traditional resin adhesives provides an alternative way for "carbon reduction and pollution reduction". Lignosulfonic acid is a natural polymer and an anionic surfactant. It has strong dispersing ability and is suitable for dispersing solid substances in an aqueous medium. Due to different molecular weights and functional groups, it has different degrees of dispersibility, can adsorb on the surface of various solid particles, can carry out metal ion exchange, and because there are various active groups in its organizational structure, it can produce condensation or form hydrogen bonds with other compounds. Natural wood powder is a waste product generated during wood processing, usually directly discarded or used for landfill treatment, and it is difficult to be efficiently utilized. After being treated in a deep eutectic solvent, the wood powder can be effectively deconstructed, completely opening the oriented arrangement structure of lignin and cellulose. After further treatment, a viscous wood pulp can be formed. It has development potential to convert natural biomass materials into the matrix and binder of resin-based composites through appropriate treatment methods. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate and its preparation method, and prepare a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate with excellent antifriction performance, low wear rate, excellent water stability, good mechanical properties, weather resistance and recyclability.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A preparation method of a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate, comprising the following steps:

[0008] Step 1: Immerse 3-8 g of activated short carbon fibers in 200-500 mL of 40 wt% sucrose solution, place the container in a microwave reactor for microwave treatment for 20-60 minutes, separate and dry after the reaction to obtain sucrose-functionalized short carbon fibers;

[0009] Step 2: Mix waste wood powder, choline chloride and oxalic acid dihydrate in a mass ratio of 1:(10-15):(10-15), continuously heat and stir at 100 °C for 3-4 hours, filter and wash the mixture, and disperse the filter residue in distilled water to form an aqueous dispersion with a lignocellulose mass fraction of 15-20 wt%.

[0010] Step 3: Disperse 10 g of waterborne epoxy resin and 5 - 10 g of sodium lignosulfonate successively in 50 - 100 mL of an alkaline aqueous solution with a concentration of 1.0 mol / L, then mix with 50 - 100 mL of the lignocellulose dispersion prepared in Step 2, and add 3 - 8 g of the sucrose-functionalized short carbon fibers prepared in Step 1. After continuously stirring for 2 - 5 hours, a precursor dispersion is obtained. After casting and curing at 200 °C for 12 - 16 hours, demolding and cutting are carried out to obtain a short carbon fiber-reinforced wood-epoxy paper-based friction plate.

[0011] The present invention also has the following technical features:

[0012] Preferably, the activation treatment method of the short carbon fibers in Step 1 is to ultrasonically treat 10 g of short carbon fibers in a solution of equal volume mixture of 200 mL of acetone and ethanol for more than 6 hours and then separate them, and dry them at 60 °C for 12 h.

[0013] Preferably, the preparation method of the 40 wt% sucrose solution in Step 1 is to disperse sucrose solid powder in a solution of equal volume mixture of ethyl acetate and water to prepare a 40 wt% sucrose solution.

[0014] Preferably, the power of the microwave treatment in Step 1 is 500 - 800 W.

[0015] Preferably, the drying in Step 1 is drying at 60 °C for 12 h.

[0016] Preferably, the waste wood powder in Step 2 includes one or a mixture of poplar wood powder, Scotch pine wood powder, willow wood powder, peach wood powder, bamboo wood powder, rice husk powder, straw powder, apple wood powder, and basswood powder.

[0017] Preferably, the washing method in Step 2 is washing with distilled water 3 - 5 times.

[0018] Preferably, the alkaline aqueous solution in Step 3 is an aqueous solution of one or a mixture of sodium hydroxide, potassium hydroxide, or calcium hydroxide.

[0019] The present invention also protects a short carbon fiber-reinforced wood-epoxy paper-based friction plate prepared by the method as described above.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] The short carbon fiber-reinforced wood-epoxy composite prepared by the present invention contains a large amount of cellulose. After lignin is dissolved into small molecules, it binds to the hydrophilic functional groups on the surface of micro-nano cellulose through hydrogen bonds, and then further undergoes hydrogen bond interaction with epoxy molecules, and is deposited on the surface of functionalized short carbon fibers under the activation of sodium lignosulfonate. Functionalizing the surface of carbon fibers with sucrose molecules can promote the interfacial interaction between the reinforcement and the matrix, thereby constructing a lignin-cellulose-carbon fiber multi-level reinforcement structure with strong hydrogen bond action at the composite interface; at the same time, epoxy resin further fills the voids of the composite, making its structure more compact, and further improving the mechanical strength of the short carbon fiber-reinforced wood-epoxy composite. While playing a reinforcing role, the composite also has high wear resistance and low wear rate; the prepared short carbon fiber-reinforced wood-epoxy composite shows excellent antifriction performance, low wear rate, excellent water stability, good mechanical properties, weather resistance and recyclability after curing and forming, achieving a good balance between the mechanical stability and sustainability of resin-based composites;

[0022] The raw materials used in the present invention are inexpensive. The natural wood raw materials used have the advantages of wide sources, large reserves, green, environmental protection and pollution-free. Using lignocellulose extracted from wood raw materials as a functional filler enhances the sustainability of the resin matrix without using any toxic solvents, forming a low-carbon and environmentally friendly preparation system. The biomass raw materials used reduce people's excessive dependence on petroleum and reduce greenhouse gas emissions. Description of the Drawings

[0023] Figure 1 is the optical microscope morphology diagram of the functionalized short carbon fibers prepared in Example 1;

[0024] Figure 2 is the SEM morphology diagram of the tear surface of the short carbon fiber-reinforced wood-epoxy composite prepared in Example 1;

[0025] Figure 3 is the optical microscope surface morphology diagram of the short carbon fiber-reinforced wood-epoxy composite prepared in Example 2;

[0026] Figure 4 is the surface SEM diagram of the short carbon fiber-reinforced wood-epoxy composite prepared in Example 2;

[0027] Figure 5 is the infrared spectrum diagram of the short carbon fiber-reinforced wood-epoxy composite prepared in Example 3;

[0028] Figure 6 is the thermal stability performance test diagram of the short carbon fiber-reinforced wood-epoxy composite prepared in Example 3;

[0029] Figure 7 is the friction coefficient curve of the short carbon fiber reinforced wood-epoxy composite prepared in Example 3;

[0030] Figure 8 is the wear performance diagram of the short carbon fiber reinforced wood-epoxy composite prepared in Example 4. Detailed implementation mode

[0031] The following further elaborates on the specific content of the present invention in conjunction with examples.

[0032] In the following examples, the activation treatment method of short carbon fibers is to take out 10 g of short carbon fibers after ultrasonic treatment in a solution of 200 mL of acetone and ethanol in equal volume for more than 6 hours, and dry them at 60 °C for 12 h for standby; the preparation method of the sucrose solution is to disperse sucrose solid powder in a solution of ethyl acetate and water in equal volume to prepare a 40 wt% sucrose solution;

[0033] The waste wood powder is one or a mixture of poplar wood powder, Mongolian pine wood powder, willow wood powder, peach wood powder, bamboo wood powder, rice husk powder, straw powder, apple wood powder, and basswood powder.

[0034] Example 1

[0035] A preparation method of a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate, comprising the following steps:

[0036] Step 1: Completely immerse 3 g of activated short carbon fibers in 200 mL of sucrose solution, place the container in a microwave reactor for microwave treatment (800 W) for 20 minutes, and then separate and dry (60 °C, 12 h) to obtain sucrose-functionalized short carbon fibers;

[0037] Step 2: Mix 2 g of poplar wood powder, 20 g of choline chloride, and 20 g of oxalic acid dihydrate evenly, continuously heat and stir at 100 °C for 3 hours, filter and wash the mixture 3 times with water, and then disperse the filter residue in distilled water to form an aqueous dispersion with a mass fraction of wood cellulose of 15 wt%;

[0038] Step 3: Disperse 10 g of waterborne epoxy resin and 5 g of sodium lignosulfonate in 50 mL of 1.0 mol / L sodium hydroxide aqueous solution, then mix with 50 mL of wood cellulose dispersion, add 3 g of functionalized short carbon fibers, continuously stir for 2 hours to obtain a precursor dispersion, pour it into a mold and cure at 200 °C for 12 hours, and obtain a short carbon fiber reinforced wood-epoxy friction plate through demolding and cutting.

[0039] Example 2

[0040] A preparation method of a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate, comprising the following steps:

[0041] Step 1: Completely immerse 8 g of activated short carbon fibers in 500 mL of sucrose solution, place the container in a microwave reactor for microwave treatment (500 W) for 60 minutes, separate and dry (60 °C, 12 h) to obtain sucrose-functionalized short carbon fibers;

[0042] Step 2: Mix 2 g of bamboo and wood powder, 30 g of choline chloride and 30 g of oxalic acid dihydrate evenly, continuously heat and stir at 100 °C for 4 hours, filter and wash the mixed solution 5 times, and disperse the filter residue in distilled water to form an aqueous dispersion with a mass fraction of wood cellulose of 20 wt%;

[0043] Step 3: Disperse 10 g of waterborne epoxy resin and 10 g of sodium lignosulfonate in 100 mL of 1.0 mol / L potassium hydroxide aqueous solution, then mix with 100 mL of wood cellulose dispersion, add 8 g of functionalized short carbon fibers, continuously stir for 5 hours to obtain a precursor dispersion, cast it in a mold and cure at 200 °C for 16 hours, and obtain a short carbon fiber reinforced wood-epoxy friction plate through demolding and cutting.

[0044] Example 3

[0045] A preparation method of a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate, comprising the following steps:

[0046] Step 1: Completely immerse 5 g of activated short carbon fibers in 300 mL of sucrose solution, place the container in a microwave reactor for microwave treatment (600 W) for 40 minutes, separate and dry (60 °C, 12 h) to obtain sucrose-functionalized short carbon fibers;

[0047] Step 2: Mix 2 g of straw powder, 25 g of choline chloride and 25 g of oxalic acid dihydrate evenly, continuously heat and stir at 100 °C for 3 hours, filter and wash the mixed solution 4 times, and disperse the filter residue in distilled water to form an aqueous dispersion with a mass fraction of wood cellulose of 18 wt%;

[0048] Step 3: Disperse 10 g of waterborne epoxy resin and 8 g of sodium lignosulfonate in 80 mL of 1.0 mol / L calcium hydroxide aqueous solution, then mix with 80 mL of wood cellulose dispersion, add 5 g of functionalized short carbon fibers, continuously stir for 4 hours to obtain a precursor dispersion, cast it in a mold and cure at 200 °C for 14 hours, and obtain a short carbon fiber reinforced wood-epoxy friction plate through demolding and cutting.

[0049] Example 4

[0050] A preparation method of a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate, comprising the following steps:

[0051] Step 1: Immerse 5 g of activated short carbon fibers completely in 400 mL of sucrose solution, place the container in a microwave reactor for microwave treatment (700 W) for 50 minutes, separate and dry (60 °C, 12 h) to obtain sucrose-functionalized short carbon fibers;

[0052] Step 2: Mix 2 g of the mixed powder of bamboo wood powder and rice husk powder, 20 g of choline chloride and 20 g of oxalic acid dihydrate evenly, continuously heat and stir at 100 °C for 3.5 hours, filter and wash the mixed solution 5 times, and disperse the filter residue in distilled water to form an aqueous dispersion with a lignocellulose mass fraction of 16 wt%;

[0053] Step 3: Disperse 10 g of waterborne epoxy resin and 6 g of sodium lignosulfonate in 50 mL of an aqueous solution prepared by mixing sodium hydroxide and potassium hydroxide in any proportion at 1.0 mol / L, then mix with 50 mL of lignocellulose dispersion, add 5 g of functionalized short carbon fibers, continuously stir for 4 hours to obtain a precursor dispersion, cast it in a mold and cure at 200 °C for 12 hours, and obtain a short carbon fiber reinforced wood-epoxy-based friction plate through demolding and cutting.

[0054] Please refer to Figure 1 As shown, it is the optical microscope morphology diagram of the functionalized short carbon fibers prepared in Example 1. We can obviously observe that a large number of attachments have formed on the surface of the carbon fibers. This is because the carbon fibers have carried a large number of hydroxyl groups and oxygen-containing groups on the surface after a long time of activation treatment, which is conducive to the interaction between sucrose macromolecules and the carbon fiber surface during the sucrose functionalization process and causes agglomeration, resulting in sugar aggregates; during the sucrose functionalization process of carbon fibers, there is no need to perform carbonization treatment on the functionalized carbon fibers, avoiding the consumption of a large amount of energy and unnecessary steps.

[0055] Please refer to Figure 2 As shown, it is the SEM morphology diagram of the tear surface of the carbon fiber reinforced wood-epoxy-based composite prepared in Example 1. It can be found that the carbon fibers are randomly distributed in the matrix of the paper-based friction plate, which will contribute to the entanglement of carbon fibers in the wood-epoxy resin matrix and the elimination of gaps, greatly promoting the densification of the green body, so that it obtains excellent mechanical stability and high wear resistance after high-temperature curing treatment; during this process, sodium lignosulfonate can effectively enhance the compatibility between epoxy resin and lignocellulose, enhance its adhesion with carbon fibers, and make a very tight structure form between the components.

[0056] Please refer to Figure 3 and Figure 4As shown, it is the surface light microscope morphology diagram and surface SEM diagram of the short carbon fiber reinforced wood-epoxy composite prepared in Example 2. It can be found that the paper-based friction plate prepared by the present invention has a relatively rough surface, and there are a large number of uneven protrusions on the microscopic surface, which will greatly promote the wear resistance of the paper-based friction plate. Because the paper-based friction plate as a friction material must have sufficient high wear resistance to exert stable friction performance, the surface protrusions can serve as a good transition layer to improve the friction force and the dynamic and static friction coefficients.

[0057] Please refer to Figure 5 As shown, it is the infrared spectrum diagram of the short carbon fiber reinforced wood-epoxy composite prepared in Example 3. In order to further detect the chemical reaction of epoxy resin in the lignocellulose matrix and its interaction with the lignocellulose components, the infrared spectrum of the paper-based friction plate was recorded. The peaks near 3390 and 2920 cm -1 are attributed to the O-H stretching of the hydroxyl groups in the waterborne epoxy resin and lignocellulose and the C-H stretching of the methylene group, and the absorbance at 816 cm -1 corresponds to the CH group of the para-substituted benzene ring in the epoxy resin. In addition, there are typical infrared peaks corresponding to the lignocellulose part, indicating the deposition of lignocellulose and its complete coverage and protection of the short carbon fibers.

[0058] Please refer to Figure 6 As shown, it is the heat resistance stability test diagram of the short carbon fiber reinforced wood-epoxy composite prepared in Example 3. Using a xenon lamp to simulate sunlight irradiation, at a light power density of 200 mW / cm 3 (about 2 sun energies), within the 240-minute range of continuous irradiation, the final surface temperature of the friction plate reaches 75 °C, and under continuous irradiation, its final thermal mass loss is less than 0.7%. This is mainly because during the high-temperature curing process, the components in the precursor slurry form a dense integrated structure, and almost all the moisture is lost, obtaining excellent mechanical stability and heat resistance.

[0059] Please refer to Figure 7As shown, it is the friction coefficient curve graph of the short carbon fiber reinforced wood-epoxy composite prepared by Example 3. As a key component applied to light transmission machinery to perform braking and transmission functions, relatively high requirements are put forward for its friction performance. The present invention uses wood cellulose as the wear-resistant seasoning of the paper-based friction plate, enhances the compatibility between epoxy resin and wood cellulose through sodium lignosulfonate, and promotes the bonding strength between the functionalized short carbon fibers and each component. Wood cellulose deposits on the surface of the paper-based friction plate, having a high surface roughness, and can be used as a natural wear-resistant layer to enhance the wear resistance of the paper-based friction plate. Finally, the paper-based friction plate prepared by the present invention has a sufficiently high friction coefficient (between 0.2 and 0.4), meeting the performance requirements of the paper-based friction material (as a friction material).

[0060] Please refer to Figure 8 As shown, it is the wear morphology graph of the short carbon fiber reinforced wood-epoxy composite prepared by Example 4. The surface of the paper-based friction plate becomes smoother after undergoing the friction test, and relatively clear wear marks are generated. However, the wear-resistant layer on the surface of the paper-based friction plate does not show obvious wear, the protrusion structure on its surface remains intact, the overall material does not undergo any fatigue fracture or crack generation, and no obvious wear debris is generated, indicating that the paper-based friction plate prepared by the present invention has high anti-wear performance.

[0061] Although the content of the present invention has been introduced in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention.

Claims

1. Preparation method of short carbon fiber reinforced wood-epoxy resin type paper-based friction plate, characterized in that, it includes the following steps: Step 1: Immerse 3-8 g of activated short carbon fibers in 200-500 mL of 40 wt% sucrose solution, place the container in a microwave reactor for microwave treatment for 20-60 minutes, separate and dry after the reaction to obtain sucrose-functionalized short carbon fibers; The activation treatment method of the short carbon fibers is to ultrasonically treat 10 g of short carbon fibers in a solution of equal volume mixture of 200 mL of acetone and ethanol for more than 6 hours, then separate, and dry at 60 °C for 12 h; Step 2: Mix waste wood powder, choline chloride and oxalic acid dihydrate evenly according to the mass ratio of 1:(10-15):(10-15), continuously heat and stir at 100 °C for 3-4 hours, filter and wash the mixture, and then disperse the filter residue in distilled water to form an aqueous dispersion with a mass fraction of wood cellulose of 15-20 wt%; Step 3: Disperse 10 g of water-based epoxy resin and 5-10 g of sodium lignosulfonate in 50-100 mL of alkaline aqueous solution with a concentration of 1.0 mol / L in sequence, then mix with 50-100 mL of the wood cellulose dispersion prepared in Step 2, add 3-8 g of the sucrose-functionalized short carbon fibers prepared in Step 1, continuously stir for 2-5 hours to obtain a precursor dispersion, and after casting and curing at 200 °C for 12-16 hours, demold and cut to obtain a short carbon fiber reinforced wood-epoxy resin type paper-based friction plate.

2. The preparation method of the short carbon fiber reinforced wood-epoxy resin type paper-based friction plate as described in claim 1, characterized in that, the preparation method of the 40 wt% sucrose solution described in Step 1 is to disperse sucrose solid powder in a solution of equal volume mixture of ethyl acetate and water to prepare a 40 wt% sucrose solution.

3. The preparation method of the short carbon fiber reinforced wood-epoxy resin type paper-based friction plate as described in claim 1, characterized in that, the power of the microwave treatment described in Step 1 is 500-800 W.

4. The preparation method of the short carbon fiber reinforced wood-epoxy resin type paper-based friction plate as described in claim 1, characterized in that, the drying described in Step 1 is drying at 60 °C for 12 h.

5. The preparation method of the short carbon fiber reinforced wood-epoxy resin type paper-based friction plate as described in claim 1, characterized in that, the waste wood powder described in Step 2 includes one or a mixture of poplar wood powder, Scotch pine wood powder, willow wood powder, peach wood powder, bamboo wood powder, rice husk powder, straw powder, apple wood powder, basswood powder.

6. The preparation method of the short carbon fiber reinforced wood-epoxy resin type paper-based friction plate as described in claim 1, characterized in that, the washing method described in Step 2 is washing with distilled water 3-5 times.

7. The preparation method of the short carbon fiber reinforced wood-epoxy resin type paper-based friction plate as described in claim 1, characterized in that, the alkaline aqueous solution described in Step 3 is an aqueous solution of one or a mixture of sodium hydroxide, potassium hydroxide or calcium hydroxide.

8. A short carbon fiber reinforced wood-epoxy paper-based friction plate prepared by the method according to any one of claims 1 to 7.

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