A modified carbon fiber material and a method for producing the same

Abstract

The application provides a modified carbon fiber material and a preparation method thereof, and comprises the following steps: S1, dissolving a polyurethane reinforcing additive in anhydrous ethanol to obtain a first mixed solution; S2, pouring the first mixed solution into EL2 epoxy lamination resin, stirring to obtain a second mixed solution, heating the second mixed solution, and then cooling and preparing; S3, uniformly stirring GC polyester gel coating and coating the GC polyester gel coating on a mold, and standing until the surface is not sticky; S4, uniformly coating the second mixed solution on the surface of the GC polyester gel coating; S5, covering twill carbon fiber material on the GC polyester gel coating coated with the second mixed solution, and brushing a layer of modified EL epoxy resin on the twill carbon fiber material; S6, repeating step S5 at least once; S7, extruding the mold to discharge air bubbles, and brushing off the excess modified EL epoxy resin with a brush; and S8, standing and demolding to obtain the modified carbon fiber material. The modified carbon fiber material has strain rate sensitivity, and can improve the brittleness of a traditional carbon fiber material.

Description

Technical Field

[0001] This application relates to the field of carbon fiber materials technology, specifically to a modified carbon fiber material and its preparation method. Background Technology

[0002] Carbon fiber is an inorganic polymer fiber with a carbon content of over 90%. Due to its high carbon content, it can be used to manufacture composite materials with high-temperature resistance. Applications of high-temperature resistant materials include aerospace, military, batteries, environmental protection, automotive, and construction. Carbon fiber production consists of major processes such as precursor fiber, pre-oxidation, and carbonization, plus several minor processes within each major process. Twill carbon fiber is produced by steaming pre-oxidized polyacrylonitrile filaments, followed by processes such as filament splitting, fiber feeding, direction changing, pressure heating, and resin impregnation to form twill carbon fibers. This results in carbon fiber sheets with fuzzy or barbed pits on the surface and a layer of resin coating. This coating increases the adhesion of the carbon fiber, prevents wrinkling of the sheet, and improves air venting during molding.

[0003] However, the significant brittleness and insufficient toughness of carbon fiber materials limit their applications in certain areas. Furthermore, if carbon fiber materials possessed strain rate sensitivity, they would find wider applications in numerous fields, including biomedicine.

[0004] In view of this, this application proposes a modified carbon fiber material and its preparation method, which can obtain a carbon fiber material with strain rate sensitivity and improve the brittleness of the carbon fiber material. Summary of the Invention

[0005] To address the problems of brittleness and insufficient toughness in existing carbon fiber materials, this application provides a modified carbon fiber material and its preparation method to solve the aforementioned technical defects.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing modified carbon fiber materials, comprising the following steps:

[0008] S1. Dissolve the polyurethane reinforcing agent in anhydrous ethanol to obtain the first mixed solution;

[0009] S2. Pour the first mixed solution into EL2 epoxy laminated resin, stir to obtain the second mixed solution, heat the second mixed solution and then let it cool for later use.

[0010] S3. Stir the GC polyester gel coat evenly and apply it to the mold. Let it stand until the surface is no longer sticky.

[0011] S4. Apply the second mixed solution evenly to the surface of the GC polyester gel coat;

[0012] S5. Cover the twill carbon fiber material onto the GC polyester gel coat coated with the second mixed solution, and then brush on a layer of modified EL epoxy resin.

[0013] S6. Repeat step S5 at least once;

[0014] S7. Extrude the mold to remove air bubbles and brush off excess modified EL epoxy resin;

[0015] S8. After standing, the modified carbon fiber material can be obtained by demolding.

[0016] Preferably, in step S1, the mass ratio of polyurethane reinforcing agent to anhydrous ethanol is 1:1.

[0017] Preferably, in step S2, the mass ratio of the first mixed solution to EL2 epoxy laminated resin is 1:9.

[0018] Preferably, in step S2, the second mixed solution is heated to 80°C-100°C under stirring conditions, and then cooled for later use.

[0019] Preferably, in step S3, the GC polyester gel coat is stirred evenly and then coated onto the mold with a thickness of 0.3-0.4 mm, and left to stand until the surface is no longer sticky.

[0020] Preferably, in step S3, the GC polyester gel coat is stirred evenly and then applied to the mold, and left to stand for 1 hour until the surface is no longer sticky.

[0021] Preferably, in step S8, the modified carbon fiber material can be obtained by demolding after standing for at least 24 hours.

[0022] Secondly, the present invention proposes a modified carbon fiber material, which is prepared according to any of the preparation methods of modified carbon fiber materials described above.

[0023] Compared with the prior art, the beneficial results of the present invention are as follows:

[0024] (1) Significantly improves the performance of carbon fiber materials: By using polyurethane reinforcing agents and EL2 epoxy laminated resin for mixed modification, the brittleness of traditional carbon fiber materials is effectively improved and their toughness is enhanced. When subjected to external forces, this modified carbon fiber material can exhibit better impact resistance and durability, thereby broadening its application fields, especially performing well in occasions requiring high-toughness materials.

[0025] (2) Improved strain rate sensitivity: After modification by the present invention, the carbon fiber material's sensitivity to strain rate is significantly improved. This means that in fields such as biomedicine and sports equipment, where materials need to respond quickly to external mechanical stimuli, the modified carbon fiber material of the present invention can provide better comfort and performance.

[0026] (3) Simplified preparation process and reduced costs: The preparation method of this invention is relatively simple and does not require complex equipment or harsh conditions of high temperature and high pressure. Through reasonable proportioning and process control, production costs can be effectively reduced and production efficiency improved while ensuring the modification effect. This is of great significance for promoting the widespread application of carbon fiber materials.

[0027] (4) Optimize coating process and improve material quality: During the preparation process, the uniformity and consistency of the modified carbon fiber material are ensured by precisely controlling the coating thickness and settling time of the GC polyester gel coat, as well as the coating and repeated brushing times of the modified EL epoxy resin. This not only improves the quality stability of the material, but also helps to reduce waste and defect rate in the production process.

[0028] (5) Environmentally friendly and efficient, easy to promote: The raw materials used in the preparation method of this invention are all environmentally friendly materials, and the entire preparation process has no harmful emissions, which meets the requirements of modern industry for environmental protection and sustainable development. At the same time, due to the simple preparation process and low cost, the modified carbon fiber material of this invention is easier to promote and apply. Attached Figure Description

[0029] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments, taken with reference to the accompanying drawings:

[0030] Figure 1 This is a flowchart of a method for preparing a modified carbon fiber material according to a specific embodiment of this application. Detailed Implementation

[0031] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] Figure 1 A flowchart illustrating a method for preparing a modified carbon fiber material according to a specific embodiment of this application is shown, as follows: Figure 1 As shown, this invention proposes a method for preparing modified carbon fiber materials, comprising the following steps:

[0034] S1. Dissolve the polyurethane reinforcing agent in anhydrous ethanol to obtain the first mixed solution;

[0035] S2. Pour the first mixed solution into EL2 epoxy laminated resin, stir to obtain the second mixed solution, heat the second mixed solution and then let it cool for later use.

[0036] S3. Stir the GC polyester gel coat evenly and apply it to the mold. Let it stand until the surface is no longer sticky.

[0037] S4. Apply the second mixed solution evenly to the surface of the GC polyester gel coat;

[0038] S5. Cover the twill carbon fiber material onto the GC polyester gel coat coated with the second mixed solution, and then brush on a layer of modified EL epoxy resin.

[0039] S6. Repeat step S5 at least once;

[0040] S7. Extrude the mold to remove air bubbles and brush off excess modified EL epoxy resin;

[0041] S8. After standing, the modified carbon fiber material can be obtained by demolding.

[0042] Example 1:

[0043] Dissolve 5g of polyurethane reinforcing agent in 5g of anhydrous ethanol and stir until homogeneous to obtain a first mixed solution. Pour the first mixed solution into 90g of EL2 epoxy laminating resin to obtain a second mixed solution. Heat the second mixed solution to 80℃-100℃ while stirring, and then let it cool for later use. Preferably, the second mixed solution is heated to 80℃. It should be understood that 80℃ is the temperature at which alcohol and water begin to azeotropically; below 80℃, alcohol and water will not evaporate completely; while above 100℃, resources are wasted and other compounds may be damaged.

[0044] Preparation of carbon fiber material: Prepare a suitable mold, stir the GC polyester gel coat evenly, and apply it to the mold to a thickness of 0.3-0.4 mm. A thickness less than 0.3 mm or greater than 0.4 mm will result in low bonding strength. Let it stand for 2 hours until the surface is no longer sticky. Repeated experiments showed that a standing time of less than 2 hours results in excessive stickiness, while a standing time of more than 3 hours results in insufficient viscosity.

[0045] Apply the modified EL epoxy resin evenly to the dried GC polyester gel coat surface to a thickness of 0.3-0.4 mm. If the thickness is less than 0.3 mm or greater than 0.4 mm, the bond strength will be low.

[0046] Apply a layer of modified EL2 epoxy resin to a GC polyester gel coat coated with twill carbon fiber. Repeat this process.

[0047] Gently press the entire surface or a portion of the mold coated with EL epoxy resin and twill carbon fiber to remove air bubbles, then carefully brush away excess resin. Specifically, you can use your palm, fingers, or a specialized tool (such as a scraper, roller, etc., depending on the actual situation) to flatten or roll the mold surface. It is important to ensure that the pressure is moderate—enough to remove air bubbles without damaging the carbon fiber material or disrupting its structure.

[0048] After leaving it overnight (i.e., 24 hours or more), carefully remove the carbon fiber material from the mold. It should be understood that the viscosity is high and it is difficult to demold if the time is less than 24 hours; if the time is more than 24 hours, there is no effect.

[0049] Example 2:

[0050] (1) Dissolve the polyurethane reinforcing agent in anhydrous ethanol. The mass ratio of the polyurethane reinforcing agent to anhydrous ethanol is 1:1.

[0051] (2) Pour the solution into EL2 epoxy laminated resin. The mass ratio of the solution to the epoxy resin is 1:9. Heat the mixture to 80 degrees Celsius while stirring, and then let it cool for later use.

[0052] (3) Prepare a suitable mold, stir the GC polyester gel coat evenly, apply it to the mold with a thickness of 0.3-0.4mm, and let it stand for 1 hour until the surface is no longer sticky.

[0053] (4) Apply the modified EL2 epoxy resin evenly to the dried GC polyester gel coat surface.

[0054] (5) Lay a sheet of twill carbon fiber on the EL2 epoxy laminated resin film with the fiber angle at 0°, then use a brush to spread the EL2 epoxy laminated resin evenly, and brush a second layer of modified EL2 epoxy laminated resin with the fiber angle at 90°.

[0055] (6) Repeat step (5).

[0056] (7) Brush the third layer of modified EL2 epoxy laminate resin at a fiber angle of 0°.

[0057] (8) Repeat step (5).

[0058] (9) Brush the fourth layer of modified EL2 epoxy laminate resin at a fiber angle of 90°.

[0059] (10) Gently squeeze out the air bubbles and carefully brush off the excess resin.

[0060] (11) After being placed for 24 hours or more, the modified carbon fiber material is obtained after demolding.

[0061] In a specific embodiment, the twill carbon fiber material is Toray T800 from Japan.

[0062] Alternatively, the preparation method of twill carbon fiber material is as follows:

[0063] A sizing solution was prepared by mixing polyacrylonitrile pre-oxidized yarn with an average monofilament diameter of 7 micrometers and an epoxy resin solution with a viscosity of 4500 mPa·s at a ratio of 10:3. This solution was used to impregnate the pre-oxidized yarn, resulting in an epoxy resin content of 16% on the surface of the pre-oxidized yarn. The pre-oxidized yarn was then heated in a drying cylinder with a heat medium temperature of 180 degrees Celsius to obtain carbon fiber yarn with an epoxy resin content of 16%.

[0064] Four layers of carbon fiber impregnated with 16% epoxy resin were subjected to four impregnation, drying, cooling and winding processes to obtain twill carbon fiber material with a single filament yarn diameter of 7 micrometers and an epoxy resin content of 16%.

[0065] The present invention also proposes a modified carbon fiber material, which is prepared according to any of the preparation methods of modified carbon fiber materials described above.

[0066] This invention addresses the shortcomings of existing carbon fiber materials, such as lack of strain sensitivity and high brittleness, by modifying the carbon fiber material. The resulting carbon fiber material exhibits strain sensitivity, becoming rigid instantly upon application of external force, and then undergoing elastic deformation under slow application of external force. Furthermore, it improves the toughness of the carbon fiber material to a certain extent. Moreover, the equipment used in this invention is simple, requiring no harsh conditions of high temperature and high pressure, making it both environmentally friendly and efficient.

[0067] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for preparing a modified carbon fiber material, characterized in that, Includes the following steps: S1. Dissolve the polyurethane reinforcing agent in anhydrous ethanol to obtain a first mixed solution, wherein the mass ratio of the polyurethane reinforcing agent to the anhydrous ethanol is 1:

1. S2. Pour the first mixed solution into EL2 epoxy laminated resin, stir to obtain a second mixed solution, the mass ratio of the first mixed solution to the EL2 epoxy laminated resin is 1:9, heat the second mixed solution to 80℃-100℃ and then let it cool for later use. S3. Stir the GC polyester gel coat evenly and apply it to the mold. Let it stand until the surface is no longer sticky. S4. The second mixed solution is evenly coated onto the surface of the GC polyester gel coat; S5. The twill carbon fiber material is coated onto the GC polyester gel coat coated with the second mixed solution, and then a layer of modified EL epoxy resin is brushed on it. S6. Repeat step S5 at least once; S7. Squeeze the mold to expel air bubbles and brush off excess modified EL epoxy resin; S8. Modified carbon fiber material can be obtained by demolding after standing for at least 24 hours. In step S5, the preparation method of the twill carbon fiber material is as follows: A sizing solution was prepared by mixing polyacrylonitrile pre-oxidized yarn with an average monofilament yarn diameter of 7 micrometers and an epoxy resin solution with a viscosity of 4500 mPa·s at a ratio of 10:

3. The pre-oxidized yarn was then impregnated with the solution to achieve an epoxy resin content of 16% on the surface of the pre-oxidized yarn. The pre-oxidized yarn was then heated in a drying cylinder with a heat medium temperature of 180 degrees Celsius to obtain carbon fiber with an epoxy resin content of 16%. Four layers of carbon fiber with an epoxy resin content of 16% were then subjected to four impregnation, drying, cooling, and winding processes to obtain a twill carbon fiber material with a monofilament yarn diameter of 7 micrometers and an epoxy resin content of 16%.

2. The method for preparing the modified carbon fiber material according to claim 1, characterized in that, In step S3, the GC polyester gel coat is stirred evenly and then coated onto the mold to a thickness of 0.3-0.4 mm. It is then left to stand until the surface is no longer sticky.

3. The method for preparing the modified carbon fiber material according to claim 1, characterized in that, In step S3, the GC polyester gel coat is stirred evenly and then applied to the mold, and left to stand for 1 hour until the surface is no longer sticky.

4. A modified carbon fiber material, characterized in that, The modified carbon fiber material was prepared according to any one of the preparation methods described in claims 1-3.

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