Preparation process of carbon fiber hard felt capable of improving interlayer strength

Abstract

The invention relates to the technical field of preparation of carbon fiber felts, and particularly discloses a preparation process of a carbon fiber hard felt capable of improving interlayer strength, which comprises the following steps: (1) immersing the carbon fiber hard felt into a saturated solution containing copper ions, performing ultrasonic treatment, then standing, and taking out the carbon fiber hard felt; and after completion, the carbon fiber hard felt is taken out and subjected to reduction treatment, and the copper ions are reduced into simple substances. And then, the obtained carbon fiber hard felt is subjected to heat treatment at the temperature higher than the copper melting point and in the protective atmosphere, and the pretreated carbon fiber hard felt is obtained after cooling. And (2) immersing the pretreated carbon fiber hard felt into a saturated solution containing magnesium ions, standing, taking out the carbon fiber hard felt, drying, and immersing into alkali liquor for treatment. And immersing the obtained pretreated carbon fiber hard felt into a dihydric phosphate solution, taking out and drying to obtain the carbon fiber hard felt. According to the process, the interlayer bonding strength of the carbon fiber hard felt can be effectively improved, so that the phenomena of cracking and layering are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber felt preparation, and in particular to a preparation process of carbon fiber hard felt with improved interlayer strength. Background Art

[0002] Carbon fiber rigid felt is a carbon fiber material made by impregnating organic fiber mats with a curing agent (such as a thermosetting resin) and bonding them layer by layer. The material is then pressed, cured at high temperature, carbonized, and graphitized. This material exhibits excellent thermal insulation properties and is widely used in energy conservation and environmental protection, automotive manufacturing, electronics, aerospace, and anti-static applications. Furthermore, carbon fiber rigid felt is used for electromagnetic shielding. Lining equipment housings or embedding it in building walls effectively prevents electromagnetic wave leakage and interference. Replacing traditional electromagnetic shielding materials with carbon fiber rigid felt can significantly reduce the overall weight of the equipment. For example, battery boxes for new energy vehicles made with carbon fiber rigid felt achieve significant weight reduction. However, because carbon fiber rigid felt is a layered structure formed by mechanical compression, and the subsequent carbonization and graphitization processes eliminate the curing agent's bonding properties, the bonding strength between the layers of the carbon fiber rigid felt is significantly reduced, making it prone to cracking and delamination during use. Summary of the Invention

[0003] The present invention provides a process for preparing a carbon fiber rigid felt with enhanced interlayer strength. This process not only effectively increases the interlayer bonding strength of the carbon fiber rigid felt, reducing cracking and delamination, but also further enhances the conductive properties of the carbon fiber rigid felt, thereby improving its electromagnetic shielding capability. Specifically, the technical solution of the present invention is as follows.

[0004] A process for preparing a carbon fiber rigid felt with improved interlayer strength comprises the following steps: (1) Immersing a carbon fiber rigid felt in a saturated solution containing copper ions and performing ultrasonic treatment, then allowing the solution to stand, and then taking out the carbon fiber rigid felt and performing reduction treatment to reduce the copper ions to a single substance. After the reduction, the obtained carbon fiber rigid felt is heat-treated at a temperature higher than the melting point of copper in a protective atmosphere, and then cooled to obtain a pretreated carbon fiber rigid felt.

[0005] (2) Immersing the pretreated carbon fiber hard felt in a saturated solution containing magnesium ions and allowing it to stand, taking it out and drying it, then immersing it in an alkaline solution for treatment. Then immersing the obtained pretreated carbon fiber hard felt in a dihydrogen phosphate solution and maintaining it, taking it out and drying it, thereby obtaining the product.

[0006] Furthermore, in step (1), the copper ions are provided by at least one of copper chloride, copper sulfate, copper nitrate, copper acetate, etc.

[0007] Furthermore, in step (1), the ultrasonic treatment time is 10 to 20 minutes. Optionally, the standing time is 5 to 30 minutes.

[0008] Furthermore, in step (1), the carbon fiber hard felt is placed in a sodium borohydride solution for reduction treatment. Optionally, the concentration of the sodium borohydride solution is 2-5 mol / L.

[0009] Furthermore, in step (1), the heat treatment temperature is 1120-1250° C., and the treatment time is 30-40 min.

[0010] Furthermore, in step (2), the magnesium ions are provided by at least one of magnesium chloride, magnesium sulfate, magnesium nitrate, etc. Optionally, in step (2), the standing time is not less than 10 minutes.

[0011] Furthermore, in step (2), the alkaline solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, etc. Optionally, the treatment time is not less than 5 minutes.

[0012] Furthermore, in step (2), the mass fraction of the alkali solution is 8-12%.

[0013] Furthermore, in step (2), the dihydrogen phosphate includes at least one of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, etc. Optionally, the mass fraction of the dihydrogen phosphate solution is 15-25%.

[0014] Furthermore, in step (2), the holding time is 30 to 60 minutes.

[0015] Furthermore, in step (2), the drying temperature is 80-110° C., and the drying time is 1-2 hours.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) The present invention utilizes the characteristic that the carbon fibers in the carbon fiber hard felt have a large number of pores after high-temperature carbonization and graphitization. Copper ions are first adsorbed in the fibers and on the fiber surface. After reduction, the copper ions are converted into a single substance to fill and load the pores and surface of the fibers. After completion, the obtained carbon fiber hard felt is heat-treated at a temperature higher than the melting point of copper in a protective atmosphere, and the copper element melts. After cooling, it re-solidifies, thereby connecting adjacent carbon fibers together to achieve "welding" between the carbon fibers. This not only helps to improve the strength of the carbon fibers themselves, but also effectively improves the interlayer bonding strength of the carbon fiber hard felt, reducing cracking and delamination. At the same time, the use of the copper element can further improve the conductive properties of the carbon fiber hard felt, thereby improving its electromagnetic shielding capability.

[0017] (2) The present invention further immerses the carbon fiber hard felt treated as described above into a saturated solution containing magnesium ions, thereby continuing to load magnesium ions in the residual pores of the carbon fiber and on its surface, and then uses alkali solution to obtain carbon fiber loaded with magnesium hydroxide. After encountering a dihydrogen phosphate solution, the magnesium hydroxide releases magnesium ions under the action of hydrogen ions provided by the dihydrogen phosphate solution to form struvite (NH4MgPO4•6H2O, KMgPO4•6H2O). This product has the characteristics of high strength and high bonding, which can further bond the layers of the carbon fiber hard felt, thereby obtaining a carbon fiber hard felt with high inter-layer bonding strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] Figure 1 This is a sample picture of the carbon fiber hard felt prepared in the following Example 1. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. In addition, any methods and materials similar or equivalent to those described herein may be applied to the method of the present invention. The preferred embodiments and materials described herein are for exemplary purposes only. The technical solutions of the present invention will now be described in further detail with reference to the accompanying drawings and specific examples. Example 1

[0021] A process for preparing a carbon fiber rigid felt with improved interlayer strength comprises the following steps: (1) Immerse the carbon fiber hard felt in a saturated solution of copper sulfate and ultrasonically treat it for 15 minutes (power 300W), then let it stand for 10 minutes. After the completion, take out the carbon fiber hard felt and immerse it in a sodium borohydride solution with a concentration of 4 mol / L for reduction reaction. After the completion, take out the carbon fiber hard felt, control the moisture and dry it, then place it in a heating furnace, heat it to 1200℃ at a rate of 10℃ / min in an argon protective atmosphere, keep it warm for 40 minutes, and then naturally cool it to room temperature to obtain a pretreated carbon fiber hard felt.

[0022] (2) Immerse the pretreated carbon fiber hard felt in a saturated solution of magnesium sulfate and let it stand for 20 minutes. After completion, take out the pretreated carbon fiber hard felt, dry it, and then immerse it in a 10% by mass sodium hydroxide solution and let it stand for 5 minutes. Then, dry the obtained pretreated carbon fiber hard felt in the air, immerse it in a 15% by mass potassium dihydrogen phosphate solution and let it stand for 40 minutes. After completion, take out the carbon fiber hard felt and dry it at 90°C for 2 hours to obtain the product.

[0023] 1. Test the prepared samples according to ASTM D2344. Figure 1 The interlaminar shear strength of the carbon fiber rigid felt shown here is used to measure the interlaminar bonding ability of the carbon fiber rigid felt. 2. The electromagnetic shielding capability of the carbon fiber rigid felt prepared in this example was tested according to the "Measurement Method for Shielding Effectiveness of Electromagnetic Shielding Rooms" (GB / T 12190-2006). The results are as follows: interlaminar shear strength = 53.71 MPa, shielding effectiveness = 63.12 dB. Example 2

[0024] A process for preparing a carbon fiber rigid felt with improved interlayer strength comprises the following steps: (1) Immerse the carbon fiber hard felt in a saturated solution of copper nitrate and ultrasonically treat it for 10 minutes (power 400W), then let it stand for 30 minutes. After completion, take out the carbon fiber hard felt and immerse it in a 5 mol / L sodium borohydride solution for reduction reaction. After completion, take out the carbon fiber hard felt, control the moisture and dry it, then place it in a heating furnace, heat it to 1250℃ at a rate of 10℃ / min in an argon protective atmosphere, keep it warm for 30 minutes, and then naturally cool it to room temperature to obtain a pretreated carbon fiber hard felt.

[0025] (2) Immerse the pretreated carbon fiber hard felt in a saturated solution of magnesium nitrate and allow it to stand for 10 minutes. After completion, take out the pretreated carbon fiber hard felt, dry it, and then immerse it in an 8% by mass sodium hydroxide solution and allow it to stand for 15 minutes. Then, dry the obtained pretreated carbon fiber hard felt in the air, immerse it in a 20% by mass potassium dihydrogen phosphate solution and allow it to stand for 30 minutes. After completion, take out the carbon fiber hard felt and dry it at 80°C for 2 hours to obtain the product.

[0026] 1. The interlaminar shear strength of the carbon fiber rigid felt prepared in this example was tested according to ASTM D2344, which measures the interlaminar bonding ability of the carbon fiber rigid felt. 2. The electromagnetic shielding capability of the carbon fiber rigid felt prepared in this example was tested according to the "Measurement Method for Shielding Effectiveness of Electromagnetic Shielding Rooms" (GB / T 12190-2006). The results were as follows: interlaminar shear strength = 50.93 MPa, shielding effectiveness = 61.48 dB. Example 3

[0027] A process for preparing a carbon fiber rigid felt with improved interlayer strength comprises the following steps: (1) Immerse the carbon fiber hard felt in a saturated solution of copper chloride and ultrasonically treat it for 20 minutes (power 300W), then let it stand for 5 minutes. After completion, take out the carbon fiber hard felt and immerse it in a sodium borohydride solution with a concentration of 2 mol / L for reduction reaction. After completion, take out the carbon fiber hard felt, control the moisture and dry it, then place it in a heating furnace, heat it to 1120℃ at a rate of 10℃ / min in an argon protective atmosphere, keep it warm for 35 minutes, and then naturally cool it to room temperature to obtain a pretreated carbon fiber hard felt.

[0028] (2) Immerse the pretreated carbon fiber hard felt in a saturated solution of magnesium chloride and let it stand for 15 minutes. After completion, take out the pretreated carbon fiber hard felt, dry it, and then immerse it in a 12% by mass potassium hydroxide solution and let it stand for 10 minutes. Then, dry the obtained pretreated carbon fiber hard felt in the air, immerse it in a 25% by mass potassium dihydrogen phosphate solution and let it stand for 60 minutes. After completion, take out the carbon fiber hard felt and dry it at 110°C for 1 hour to obtain the product.

[0029] 1. The interlaminar shear strength of the carbon fiber rigid felt prepared in this example was tested according to ASTM D2344, which measures the interlaminar bonding ability of the carbon fiber rigid felt. 2. The electromagnetic shielding capability of the carbon fiber rigid felt prepared in this example was tested according to the "Measurement Method for Shielding Effectiveness of Electromagnetic Shielding Rooms" (GB / T 12190-2006). The results were as follows: interlaminar shear strength = 55.04 MPa, shielding effectiveness = 58.32 dB. Example 4

[0030] A process for preparing a carbon fiber rigid felt with improved interlayer strength comprises the following steps: immersing the carbon fiber rigid felt in a saturated solution of magnesium sulfate and allowing it to stand for 20 minutes. After immersing the carbon fiber rigid felt, the felt is dried and immersed in a 10% by mass sodium hydroxide solution and allowed to stand for 5 minutes. The obtained carbon fiber rigid felt is then dried and immersed in a 15% by mass potassium dihydrogen phosphate solution and allowed to stand for 40 minutes. After immersing the carbon fiber rigid felt, the felt is removed and dried at 90°C for 2 hours to obtain the product.

[0031] 1. The interlaminar shear strength of the carbon fiber rigid felt prepared in this example was tested according to ASTM D2344, which measures the interlaminar bonding ability of the carbon fiber rigid felt. 2. The electromagnetic shielding capability of the carbon fiber rigid felt prepared in this example was tested according to the "Measurement Method for Shielding Effectiveness of Electromagnetic Shielding Rooms" (GB / T 12190-2006). The results were as follows: interlaminar shear strength = 49.43 MPa, shielding effectiveness = 52.85 dB. Example 5

[0032] A process for preparing a carbon fiber rigid felt with improved interlayer strength comprises the following steps: immersing the carbon fiber rigid felt in a saturated solution of copper nitrate, ultrasonically treating it for 10 minutes (power 400W), then allowing it to stand for 30 minutes. After the process is complete, the carbon fiber rigid felt is removed and immersed in a 5 mol / L sodium borohydride solution for a reduction reaction. After the process is complete, the carbon fiber rigid felt is removed, drained of moisture, and air-dried. The felt is then placed in a heating furnace and heated to 1250°C at a rate of 10°C / min in an argon protective atmosphere, held at that temperature for 30 minutes, and then naturally cooled to room temperature.

[0033] 1. The interlaminar shear strength of the carbon fiber rigid felt prepared in this example was tested according to ASTM D2344, which measures the interlaminar bonding ability of the carbon fiber rigid felt. 2. The electromagnetic shielding capability of the carbon fiber rigid felt prepared in this example was tested according to the "Measurement Method for Shielding Effectiveness of Electromagnetic Shielding Rooms" (GB / T 12190-2006). The results were as follows: interlaminar shear strength = 47.54 MPa, shielding effectiveness = 60.27 dB. Example 6

[0034] A process for preparing a carbon fiber rigid felt with improved interlayer strength comprises the following steps: (1) Immerse the carbon fiber hard felt in a saturated solution of copper chloride and ultrasonically treat it for 20 minutes (power 300W), then let it stand for 5 minutes. After completion, take out the carbon fiber hard felt, control the moisture and dry it in the air, then place it in a heating furnace, heat it to 1120℃ at a rate of 10℃ / min in an argon protective atmosphere, keep it warm for 35 minutes, and then naturally cool it to room temperature to obtain a pretreated carbon fiber hard felt.

[0035] (2) Immerse the pretreated carbon fiber hard felt in a saturated solution of magnesium chloride and let it stand for 15 minutes. After completion, take out the pretreated carbon fiber hard felt, dry it, and then immerse it in a 12% by mass potassium hydroxide solution and let it stand for 10 minutes. Then, dry the obtained pretreated carbon fiber hard felt in the air, immerse it in a 25% by mass potassium dihydrogen phosphate solution and let it stand for 60 minutes. After completion, take out the carbon fiber hard felt and dry it at 110°C for 1 hour to obtain the product.

[0036] 1. The interlaminar shear strength of the carbon fiber rigid felt prepared in this example was tested according to ASTM D2344, which measures the interlaminar bonding ability of the carbon fiber rigid felt. 2. The electromagnetic shielding capability of the carbon fiber rigid felt prepared in this example was tested according to the "Measurement Method for Shielding Effectiveness of Electromagnetic Shielding Rooms" (GB / T 12190-2006). The results were as follows: interlaminar shear strength = 50.16 MPa, shielding effectiveness = 48.89 dB. Example 7

[0037] A process for preparing a carbon fiber rigid felt with improved interlayer strength comprises the following steps: (1) Immerse the carbon fiber hard felt in a saturated solution of copper nitrate and ultrasonically treat it for 10 minutes (power 400W), then let it stand for 30 minutes. After the treatment, take out the carbon fiber hard felt and immerse it in a sodium borohydride solution with a concentration of 5 mol / L for reduction reaction. After the treatment, take out the carbon fiber hard felt, control the moisture and dry it in the air to obtain the pretreated carbon fiber hard felt.

[0038] (2) Immerse the pretreated carbon fiber hard felt in a saturated solution of magnesium nitrate and allow it to stand for 10 minutes. After completion, take out the pretreated carbon fiber hard felt, dry it, and then immerse it in an 8% by mass sodium hydroxide solution and allow it to stand for 15 minutes. Then, dry the obtained pretreated carbon fiber hard felt in the air, immerse it in a 20% by mass potassium dihydrogen phosphate solution and allow it to stand for 30 minutes. After completion, take out the carbon fiber hard felt and dry it at 80°C for 2 hours to obtain the product.

[0039] 1. The interlaminar shear strength of the carbon fiber rigid felt prepared in this example was tested according to ASTM D2344, which measures the interlaminar bonding ability of the carbon fiber rigid felt. 2. The electromagnetic shielding capability of the carbon fiber rigid felt prepared in this example was tested according to the "Measurement Method for Shielding Effectiveness of Electromagnetic Shielding Rooms" (GB / T 12190-2006). The results were as follows: interlaminar shear strength = 46.34 MPa, shielding effectiveness = 57.76 dB.

[0040] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A process for preparing a carbon fiber rigid felt with improved interlayer strength, characterized in that: The steps include: (1) Immersing the carbon fiber hard felt in a saturated solution containing copper ions and performing ultrasonic treatment, then allowing it to stand, and after completion, taking out the carbon fiber hard felt and performing reduction treatment to reduce the copper ions to a single substance; after completion, heat-treating the obtained carbon fiber hard felt at a temperature higher than the melting point of copper in a protective atmosphere, and cooling it to obtain a pretreated carbon fiber hard felt; (2) Immersing the pretreated carbon fiber hard felt into a saturated solution containing magnesium ions and allowing it to stand, taking out the pretreated carbon fiber hard felt after drying and then immersing it in an alkaline solution for treatment; then immersing the obtained pretreated carbon fiber hard felt in a dihydrogen phosphate solution and maintaining it, taking it out and drying it after completion, thereby obtaining the product.

2. The process for preparing a carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (1), the copper ions are provided by at least one of copper chloride, copper sulfate, copper nitrate and copper acetate.

3. The process for preparing a carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (1), the ultrasonic treatment time is 10 to 20 minutes; optionally, the standing time is 5 to 30 minutes.

4. The process for preparing a carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (1), the carbon fiber hard felt is placed in a sodium borohydride solution for reduction treatment; optionally, the concentration of the sodium borohydride solution is 2-5 mol / L.

5. The process for preparing a carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (1), the heat treatment temperature is 1120-1250° C., and the treatment time is 30-40 min.

6. The process for preparing a carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (2), the magnesium ions are provided by at least one of magnesium chloride, magnesium sulfate, and magnesium nitrate; Optionally, in step (2), the mass fraction of the alkali solution is 8-12%; Optionally, in step (2), the standing time is not less than 10 minutes.

7. The process for preparing a carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (2), the alkaline solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, and ammonia water; optionally, the treatment time is not less than 5 minutes.

8. The process for preparing a carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (2), the dihydrogen phosphate includes at least one of potassium dihydrogen phosphate and ammonium dihydrogen phosphate; optionally, the mass fraction of the dihydrogen phosphate solution is 15-25%.

9. The process for preparing a carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (2), the holding time is 30 to 60 minutes.

10. The process for preparing carbon fiber hard felt with improved interlayer strength according to claim 1, characterized in that: In step (2), the drying temperature is 80-110° C., and the drying time is 1-2 hours.

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