High-thermal-conductivity pitch-based carbon fiber multifilament separation method and monofilament detection method

Abstract

The invention provides a high-thermal-conductivity pitch-based carbon fiber multifilament separation method and a monofilament detection method, and relates to the technical field of material testing. The separation method comprises the following steps: S1, preparing a separation solution from deionized water, absolute ethyl alcohol and a surfactant according to a volume ratio of 1: (0.05-0.1): (0.05-0.1); s2, shearing the pitch-based carbon fiber multifilament by a set length, carrying out layered separation, and soaking in a separation liquid to separate the end part of the monofilament; and S3, immersing the pressure-sensitive adhesive in the separation liquid, sticking the exposed monofilament end part of the pitch-based carbon fiber multifilament in the separation liquid, and extracting to obtain the high-thermal-conductivity pitch-based carbon fiber monofilament. The invention provides a special solution and a suspension extraction method for pitch-based carbon fiber multifilaments, and the phenomena of breakage and adhesion in the monofilament separation process are effectively reduced. The separation success rate is obviously improved, and the fiber damage is reduced, so that the discreteness of a carbon fiber monofilament test result is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of material testing, and in particular to a method for separating multifilaments of high thermal conductivity asphalt-based carbon fiber and a method for detecting single filaments. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] High-performance asphalt-based carbon fiber (MPCF) is a high-performance carbon fiber with a carbon content greater than 99%. It has the advantages of high thermal conductivity, ultra-high modulus, low thermal expansion coefficient, light weight, conductivity, high strength, etc. It is widely used in the hot end components of hypersonic aircraft, large-area thin plate structures of space vehicles, heat dissipation components of electronic instrument compartments, and the force arms of the new generation of intelligent robots.

[0004] To characterize the performance of carbon fiber, it is necessary to adopt multi-scale performance evaluation and characterization, including monofilament performance, multifilament performance and composite material performance. For example, the patent with application number 202310800344X discloses a test method for the tensile strength of carbon fiber monofilaments, which can improve the efficiency of the tensile strength performance analysis of carbon fiber monofilaments and reduce the discreteness of the tensile strength test results of carbon fiber monofilaments. Carbon fiber monofilaments are separated from a bundle (1-50K) of carbon fiber products. Conventional PAN-based carbon fiber monofilaments are relatively easy to separate, while asphalt-based carbon fiber monofilaments are relatively difficult to separate: on the one hand, due to its ultra-high modulus, it breaks during the separation process, and it is difficult to obtain monofilaments of qualified length; on the other hand, the adhesion of asphalt-based carbon fiber is relatively obvious, which makes it relatively difficult to separate the monofilaments. This makes it difficult to accurately evaluate the monofilament performance of asphalt-based carbon fiber, and performance evaluation is an important indicator in the development and production of carbon fiber, which also hinders the development and production of asphalt-based carbon fiber. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for separating multifilaments of high thermal conductivity asphalt-based carbon fiber and a method for detecting single filaments, wherein the asphalt-based carbon fiber is placed in a special solution and the single filaments are separated by a suspension extraction method.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, a method for separating high thermal conductivity asphalt-based carbon fiber multifilaments comprises the following steps:

[0008] S1. Prepare a separation solution by mixing deionized water, anhydrous ethanol and a surfactant in a volume ratio of 1:(0.05-0.1):(0.05-0.1);

[0009] S2, cutting the asphalt-based carbon fiber multifilament into a set length, separating the multifilament into layers, and immersing the multifilament in a separation liquid to separate the ends of the single filaments;

[0010] S3. Immerse the pressure-sensitive adhesive in the separation liquid, adhere the exposed single filament ends of the asphalt-based carbon fiber multifilament in the separation liquid, and then pull them out to obtain high thermal conductivity asphalt-based carbon fiber single filaments.

[0011] Optionally, in S1, the surfactant includes: one or two of polypropylene glycol and toluenesulfonamide.

[0012] Optionally, in S2, the asphalt-based carbon fiber multifilament is cut into 4 to 8 cm.

[0013] Optionally, in S2, the separation interface of the laminar separation is parallel to the length direction of the single filament.

[0014] Optionally, in S2, the pitch-based carbon fiber multifilaments are suspended in a separation liquid, and the separation liquid is vibrated to separate the single filaments at the ends of the pitch-based carbon fiber multifilaments.

[0015] Optionally, in S2, the method of vibrating the separation liquid includes ultrasonic vibration and artificial shaking.

[0016] Optionally, in S3, the pressure-sensitive adhesive is one of a pressure-sensitive adhesive tape and a pressure-sensitive film.

[0017] Optionally, in S3, the pressure-sensitive adhesive is adhered to the end of the monofilament from above, and the withdrawal direction is the same as the length direction of the monofilament.

[0018] Optionally, the method further includes the step: S4, removing the monofilament from the pressure-sensitive adhesive and drying it naturally.

[0019] In a second aspect, a method for detecting high thermal conductivity asphalt-based carbon fiber monofilaments is provided, wherein the high thermal conductivity asphalt-based carbon fiber monofilaments used for detection are obtained by the above-mentioned method for separating high thermal conductivity asphalt-based carbon fiber multifilaments.

[0020] Optionally, the test content includes the tensile strength and / or thermal conductivity of the monofilament.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The present invention proposes a special solution and suspension extraction method to separate asphalt-based carbon fiber monofilaments for the specific material of asphalt-based carbon fiber, which effectively reduces the breakage and adhesion phenomena during the monofilament separation process. The separation success rate is significantly improved, and the fiber damage is reduced, thereby reducing the discreteness of the carbon fiber monofilament test results. And it is not only suitable for asphalt-based carbon fiber tows within a certain range (1~6K), but also has good adaptability to PAN-based carbon fibers of different specifications (1~50K).

[0023] 2. The separation method provided by the present invention can be used as a pre-treatment step for the performance detection of asphalt-based carbon fiber monofilaments, providing an effective means for the performance evaluation of asphalt-based carbon fiber monofilaments, which is an important contribution to the fields of materials science and engineering applications. The use of chemical reagents and the generation of waste are reduced in the process, which meets the requirements of sustainable development, and is of great significance for the research, development and production of carbon fiber materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification, 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.

[0025] Figure 1 Schematic diagram of the method for separating multifilaments of high thermal conductivity asphalt-based carbon fiber in Example 1.

[0026] Among them, 1. Petri dish; 2. filament bundle; 3. pressure-sensitive tape; 4. tweezers; 5. separation fluid. DETAILED DESCRIPTION

[0027] High-performance asphalt-based carbon fiber (MPCF) is a high-performance carbon fiber with a carbon content greater than 99%. The single-filament performance evaluation of asphalt-based carbon fiber requires separating the single filaments from a bundle (1K~6K) of asphalt-based carbon fibers. Due to the high viscosity of the sizing agent on the surface of asphalt-based carbon fibers, the mutual adhesion between the asphalt-based carbon fibers is also relatively obvious. In addition, due to the ultra-high modulus of asphalt-based carbon fibers, they are easily bent and broken during the single-filament separation process, so the separation of the single filaments is extremely difficult.

[0028] Example 1

[0029] The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments (1K specification) of this embodiment comprises the following steps:

[0030] S1, such as Figure 1 As shown, deionized water, anhydrous ethanol and polypropylene glycol are weighed in a volume ratio of 1:0.05:0.05, 100 ml, 5 ml and 5 ml respectively, to prepare separation solution 5, and a culture dish 1 is used to hold 80 ml of separation solution 5;

[0031] S2, cutting the asphalt-based carbon fiber multifilament into 8 cm lengths, and separating them into layers by manually tearing them apart, so as to separate them into a plurality of sheet-like tows 2, which are then immersed in a separation liquid 5;

[0032] S3, cut the pressure-sensitive tape 3 into a square of 1cm*0.5mm, clamp one corner of the square pressure-sensitive tape 3 with tweezers 4, place the other end of the square in the separation liquid 5 containing the fibers to be separated, slowly approach the filament bundle 2, and shake in the separation liquid 5 to make the separation liquid 5 vibrate; when some monofilaments are seen leaking out from the end of the filament bundle 2, place the square of pressure-sensitive tape 3 on the monofilament with tweezers 4, adhere the end of the monofilament from above, and pull the pressure-sensitive tape 3 out of the separation liquid 5 horizontally in a direction parallel to the length direction of the monofilament, thus completing the separation of the monofilament;

[0033] S4. After removing the monofilament adhered to the pressure-sensitive tape 3, wash it with deionized water, and dry it to obtain a high thermal conductivity asphalt-based carbon fiber monofilament.

[0034] In the separation liquid, deionized water is used as a solvent, anhydrous ethanol serves as a penetration effect, and the surfactant serves to reduce the surface tension of the liquid, thereby making it have better dispersibility and wettability.

[0035] The hardness and viscosity of pressure-sensitive tape are convenient for handling.

[0036] Example 2

[0037] The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments (6K specification) of this embodiment comprises the following steps:

[0038] S1. Weigh 100 ml, 10 ml and 10 ml of deionized water, anhydrous ethanol and toluenesulfonamide respectively in a volume ratio of 1:0.1:0.1 to prepare a separation solution, and place the separation solution in a culture dish;

[0039] S2, cutting the asphalt-based carbon fiber multifilament into 8 cm lengths, and separating them into layers by manually tearing them apart, so as to separate them into multiple sheet-like tows, immersing them in a separation liquid in a culture dish, and placing the culture dish in an ultrasonic vibration device (ultrasonic cleaning machine) to vibrate the separation liquid and the tows until separated single filaments can be observed at the ends of the tows;

[0040] S3, cut the pressure-sensitive tape into a 1cm*0.5mm square, clamp one corner of the square with tweezers, place the other end of the square in the separation liquid containing the fibers to be separated, place the pressure-sensitive tape square on the end of the monofilament with tweezers, contact the end of the monofilament from above, and pull the pressure-sensitive tape out of the water horizontally in a direction parallel to the length direction of the monofilament, thus completing the separation of the monofilament;

[0041] S4. After removing the monofilament adhered to the pressure-sensitive tape, wash it with deionized water and dry it to obtain a high thermal conductivity asphalt-based carbon fiber monofilament.

[0042] Similar to Example 1, in the separation liquid, deionized water is used as the solvent, anhydrous ethanol serves as the penetration effect, and the surfactant serves to reduce the surface tension of the liquid, so that the liquid has better dispersibility and wettability.

[0043] Since the high thermal conductivity asphalt-based carbon fiber multifilaments of 6K specifications are separated in this embodiment, the added amounts of anhydrous ethanol and surfactant are increased, and ultrasonic vibration is used to separate the single filaments.

[0044] Comparative Example 1

[0045] The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments (1K specification) of this embodiment comprises the following steps:

[0046] S1. Weigh 100 ml, 20 ml and 20 ml of deionized water, anhydrous ethanol and polypropylene glycol respectively according to the volume ratio of 1:0.2:0.2 to prepare a separation solution, and introduce the separation solution into a culture dish.

[0047] S2, cutting the asphalt-based carbon fiber multifilament into 8 cm lengths, and separating the multifilaments into layers by manually tearing them apart, so as to separate them into a plurality of sheet-like bundles, and immersing them in a separation liquid;

[0048] S3. Cut the pressure-sensitive tape into a 1cm*0.5mm square, hold one corner of the square with tweezers, place the other end of the square in the separation liquid containing the fibers to be separated, slowly approach the fibers, and shake in the separation liquid to make the separation liquid vibrate; when some monofilaments are seen leaking out, place the pressure-sensitive tape square on the monofilaments with tweezers, adhere the end of the monofilaments from above, and pull the pressure-sensitive tape out of the water horizontally in a direction parallel to the length of the monofilaments;

[0049] S4. After removing the asphalt-based carbon fiber filaments adhered to the pressure-sensitive tape, wash them with deionized water, dry them, and obtain a single fiber sample.

[0050] The sources of the high thermal conductivity asphalt-based carbon fiber multifilaments in this comparative example are the same as those in Example 1, and the difference in the method is that the proportion of anhydrous ethanol and surfactant added is significantly greater than that in Example 1.

[0051] Comparative Example 2

[0052] The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments (6K specification) of this embodiment comprises the following steps:

[0053] S1. Prepare a separation solution by mixing deionized water, anhydrous ethanol and sodium dodecylbenzene sulfonate in a volume ratio of 1:0.1:0.1, and place the separation solution in a culture dish;

[0054] S2, cutting the asphalt-based carbon fiber multifilament into 5 cm lengths, and separating them into layers by manually tearing them apart, so as to separate them into multiple sheet-like tows, immersing them in a separation liquid in a culture dish, and placing the culture dish in an ultrasonic vibration device (ultrasonic cleaning machine) to vibrate the separation liquid and the tows until separated single filaments can be observed at the ends of the tows;

[0055] S3, cut the pressure-sensitive tape into a 1cm*0.5mm square, clamp one corner of the square with tweezers, place the other end of the square in the separation liquid containing the fibers to be separated, place the pressure-sensitive tape square on the end of the monofilament with tweezers, contact the end of the monofilament from above, and pull the pressure-sensitive tape out of the water horizontally in a direction parallel to the length direction of the monofilament;

[0056] S4. After removing the asphalt-based carbon fiber filaments adhered to the pressure-sensitive tape, wash them with deionized water, dry them, and obtain a single fiber sample.

[0057] The sources of the high thermal conductivity asphalt-based carbon fiber multifilaments in this comparative example and Example 2 are the same, and the difference in the methods is that the surfactant used is sodium dodecylbenzene sulfonate.

[0058] Comparative Example 3

[0059] The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments (2K specification) of this embodiment comprises the following steps:

[0060] S1. Prepare a separation solution by mixing deionized water, anhydrous ethanol and sodium dodecylbenzene sulfonate in a volume ratio of 1:0.2:0.2, and place the separation solution in a culture dish;

[0061] S2, cutting the asphalt-based carbon fiber multifilament into 5 cm lengths, and separating them into layers by manually tearing them apart, so as to separate them into multiple sheet-like tows, immersing them in a separation liquid in a culture dish, and placing the culture dish in an ultrasonic vibration device (ultrasonic cleaning machine) to vibrate the separation liquid and the tows until separated single filaments can be observed at the ends of the tows;

[0062] S3, cut the pressure-sensitive tape into a 1cm*0.5mm square, clamp one corner of the square with tweezers, place the other end of the square in the separation liquid containing the fibers to be separated, place the pressure-sensitive tape square on the end of the monofilament with tweezers, contact the end of the monofilament from above, and pull the pressure-sensitive tape out of the water horizontally in a direction parallel to the length direction of the monofilament, thus completing the separation of the monofilament;

[0063] S4. After removing the monofilament adhered to the pressure-sensitive tape, wash it with deionized water and dry it to obtain a high thermal conductivity asphalt-based carbon fiber monofilament sample.

[0064] The high thermal conductivity asphalt-based carbon fiber multifilaments of this comparative example and Example 2 are derived from the same manufacturer, and the microscopic defects of the carbon fiber raw materials in the multifilaments are consistent with those of Example 2. The difference in method from Example 2 is that the types of additives are different and the content is higher than that of Example 2.

[0065] Example 4

[0066] A method for detecting high thermal conductivity asphalt-based carbon fiber monofilaments, the monofilaments used are obtained by the methods of the above embodiments 1, 2 and comparative examples 1, 2, and 3. 20 to 25 monofilament samples are taken for each method to evaluate their degree of discreteness.

[0067] The test content is the tensile strength of high thermal conductivity asphalt-based carbon fiber monofilaments. The test method is carried out in accordance with the Chinese patent application number 202310800344X "A method and device for testing the tensile strength of carbon fiber monofilaments", and the test results are shown in Table 1.

[0068] Table 1 Tensile strength test results of high thermal conductivity asphalt-based carbon fiber monofilaments

[0069] performance Average tensile strength (MPa) Valid samples (pcs) Coefficient of dispersion (%) Example 1 2.87 20 7.3 Example 2 2.98 18 8.9 Comparative Example 1 2.56 23 24.8 Comparative Example 2 2.49 21 25.7 Comparative Example 3 2.37 22 28.9

[0070] The dispersion coefficient refers to the degree of deviation of the test results. Since the high thermal conductivity asphalt-based carbon fiber multifilaments of the same specifications in each embodiment or comparative example are selected from the same batch of products, the performance of the monofilaments therein should be uniform. However, the dispersion coefficients of comparative examples 1, 2 and 3 are much higher than those of embodiments 1 and 2, indicating that the samples have been damaged to varying degrees during the sampling process. This damage not only leads to an increase in the dispersion coefficient, but also a decrease in the tensile strength. Therefore, the higher the average tensile strength in the measurement results and the smaller the dispersion coefficient, the less damage the sample preparation method causes to the carbon fiber monofilaments, and the better the performance of the carbon fiber monofilaments themselves can be reflected.

[0071] Example 5

[0072] A method for detecting the thermal conductivity of high thermal conductivity asphalt-based carbon fiber monofilaments, wherein the monofilaments used are obtained by the methods of the above-mentioned embodiments 1, 2 and comparative examples 1, 2 and 3, and 5 to 10 monofilaments are taken to evaluate their degree of dispersion.

[0073] The test content is the thermal conductivity of the high thermal conductivity asphalt-based carbon fiber monofilament, and the thermal conductivity of the asphalt-based carbon fiber monofilament is indirectly measured by the resistance method. The test results are shown in Table 2.

[0074] Table 2 Thermal conductivity test results of high thermal conductivity asphalt-based carbon fiber monofilament

[0075] performance Average thermal conductivity (W / (m·K)) Valid samples (pcs) Coefficient of dispersion (%) Example 1 1035.5 5 4.2 Example 2 1046.8 5 3.5 Comparative Example 1 905.4 5 10.5 Comparative Example 2 857.9 5 9.7 Comparative Example 3 923.5 5 8.6

[0076] Similar to the data results in Table 1, the dispersion coefficient refers to the degree of deviation of the test results. The performance of the monofilaments from the same batch of products should be uniform, but the dispersion coefficients of Comparative Examples 1, 2 and 3 are much higher than those of Examples 1 and 2, indicating that the test samples were damaged to varying degrees during the sampling process. This damage not only leads to an increase in the dispersion coefficient, but also leads to a decrease in the thermal conductivity test results, making the test results significantly lower than the state of the monofilaments inside the high thermal conductivity asphalt-based carbon fiber multifilaments. Therefore, the higher the average thermal conductivity in the measurement results and the smaller the dispersion coefficient, the less damage the sample preparation method causes to the carbon fiber monofilaments, and the better the performance of the carbon fiber monofilaments themselves can be reflected.

[0077] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for separating high thermal conductivity asphalt-based carbon fiber multifilaments, characterized in that the steps include: S1. Prepare a separation solution by mixing deionized water, anhydrous ethanol and a surfactant in a volume ratio of 1:(0.05-0.1):(0.05-0.1); S2, cutting the asphalt-based carbon fiber multifilament into a set length, separating the multifilament into layers, and immersing the multifilament in a separation liquid to separate the ends of the single filaments; S3. Immerse the pressure-sensitive adhesive in the separation liquid, adhere the exposed single filament ends of the asphalt-based carbon fiber multifilament in the separation liquid, and then pull them out to obtain high thermal conductivity asphalt-based carbon fiber single filaments.

2. The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments according to claim 1, characterized in that: In S1, the surfactant includes: polyethylene glycol and toluenesulfonamide.

3. The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments according to claim 1, characterized in that: In S2, the pitch-based carbon fiber multifilament is cut into 4 to 8 cm.

4. The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments according to claim 1, characterized in that: In S2, the separation interface of the lamellar separation is parallel to the length direction of the single fiber.

5. The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments according to claim 1, characterized in that: In S2, the pitch-based carbon fiber multifilaments are suspended in a separation liquid, and the separation liquid is vibrated to separate the single filaments at the ends of the pitch-based carbon fiber multifilaments.

6. The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments according to claim 5, characterized in that: Methods for vibrating the separation liquid include ultrasonic vibration and artificial shaking.

7. The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments according to claim 1, characterized in that: Pressure sensitive adhesive is a type of pressure sensitive adhesive tape and pressure sensitive film.

8. The method for separating high thermal conductivity asphalt-based carbon fiber multifilaments according to claim 1, characterized in that: The pressure-sensitive adhesive is adhered to the end of the monofilament from above, and the withdrawal direction is the same as the length direction of the monofilament.

9. The method for separating multifilaments of high thermal conductivity asphalt-based carbon fibers according to claim 1, characterized in that: The method further comprises step S4 of removing the monofilament from the pressure-sensitive adhesive and drying the monofilament naturally.

10. A method for detecting high thermal conductivity asphalt-based carbon fiber monofilaments, characterized in that: The high thermal conductivity asphalt-based carbon fiber monofilament used for testing is obtained by the above-mentioned method for separating high thermal conductivity asphalt-based carbon fiber multifilaments, and the testing content includes the tensile strength and / or thermal conductivity of the monofilament.

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