A test method for simulating carbonization process verification of spinning oil thermal performance

Abstract

This invention discloses a test method for simulating carbonization process to verify the thermogravimetric properties of spinning oil, comprising the following steps: Step S1, oiling the slurry-free carbon fiber; Step S2, designing a corresponding TGA test program based on the actual carbonization production process of carbon fiber; designing a corresponding TGA test program based on the segmented temperature range, heating rate, and atmosphere conditions of the actual carbonization production process of carbon fiber; Step S3, conducting thermogravimetric performance testing using a TGA tester; cutting the oiled slurry-free carbon fiber sample to a preset length and starting the tester for thermogravimetric testing; Step S4, verifying the thermogravimetric properties of the spinning oil based on the test results; determining whether the thermal stability of the spinning oil meets the requirements of the carbonization production process based on the thermogravimetric performance parameters obtained from the thermogravimetric test. This invention uses slurry-free carbon fiber as the carrier of the spinning oil, which is completely consistent with the application scenario of the oil in actual carbon fiber production, accurately reflecting the thermogravimetric change law of the spinning oil in the actual carbonization process.

Description

Technical Field

[0001] This invention relates to a test method for verifying the thermogravimetric properties of spinning oils by simulating a carbonization process, and belongs to the technical field of test methods for the thermogravimetric properties of spinning oils. Background Technology

[0002] Spinning oil is a key auxiliary material in the production of fibers such as PAN-based carbon fiber. Its main function is to reduce fiber surface friction and prevent fiber breakage. It also provides protection for the fibers in subsequent pre-oxidation and carbonization processes, reducing surface defects. The thermal stability (i.e., thermogravimetric properties) of the spinning oil directly affects the stability of the carbonization process and the mechanical properties of the final carbon fiber product. If the spinning oil has poor heat resistance, it will undergo premature thermal decomposition during carbonization, producing volatile substances that cause the carbon filament surface to become sticky, break, or even form surface defects, significantly reducing key performance indicators such as tensile strength and modulus of the carbon fiber.

[0003] Currently, most thermogravimetric analysis (TGA) tests for spinning oils employ the TG-DSC method. This method typically uses a single heating or isothermal mode, and the test subjects are mostly pure spinning oils or carbon fibers containing sizing, failing to perform in-situ testing on samples with oil applied to the surface of sizing-free carbon fibers. Furthermore, existing TGA test procedures are mostly general-purpose, not designed to incorporate the segmented temperatures, heating rates, and atmospheric conditions of the actual carbonization production process of carbon fibers. This leads to a disconnect between the test scenario and the actual production scenario, resulting in thermogravimetric parameters (such as thermal decomposition temperature and mass loss rate) that cannot accurately reflect the true performance of the spinning oil during the actual carbonization process.

[0004] Furthermore, existing methods for testing the thermal properties of spinning oils have significant limitations: directly heating the oiled precursor fiber to test its thermal stability is problematic because the fiber itself is not heat-resistant and is prone to degradation and damage during testing, making effective testing impossible; directly heating the pure oil for thermal analysis fails to simulate the actual decomposition state of the oil in the actual carbonization process, and cannot reflect the impact of the bonding state between the oil and the carbon fiber surface on thermal stability when using slurry-free carbon fiber as a carrier, resulting in a serious disconnect between the test results and practical applications, further reducing the practicality of the test results. Therefore, the core objective of this invention is to solve the above-mentioned testing difficulties and develop a method for verifying the thermogravimetric properties of spinning oils that is accurate, practical, and closely aligned with actual carbonization production processes. This has become a pressing technical problem in the current carbon fiber production field.

[0005] In conclusion, the existing technology obviously has inconveniences and defects in practical use, so it is necessary to improve it. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a test method for simulating carbonization process to verify the thermogravimetric properties of spinning oil. Using slurry-free carbon fiber as the carrier of the spinning oil, it is completely consistent with the application scenario of the oil in actual carbon fiber production. This avoids the problem of test results being out of touch with actual applications caused by testing pure oil or slurry-containing carbon fiber in the prior art, and accurately reflects the thermogravimetric change law of the spinning oil in the actual carbonization process.

[0007] To solve the above technical problems, the present invention adopts the following technical solution: A test method for simulating carbonization process to verify the thermogravimetric properties of spinning oils includes the following steps: Step S1, oiling treatment of pulpless carbon fiber; uniformly coat the surface of pulpless carbon fiber with spinning oil, and obtain oiled pulpless carbon fiber sample after drying. Step S2: Design the corresponding TGA test program based on the actual carbonization production process of carbon fiber; design the corresponding TGA test program based on the segmented temperature range, heating rate and atmosphere conditions of the actual carbonization production process of carbon fiber. Step S3: Perform thermogravimetric analysis using a TGA tester; cut the oiled, paste-free carbon fiber sample into a preset length and start the tester to perform the thermogravimetric analysis. Step S4: Verify the thermogravimetric properties of the spinning oil based on the test results; determine whether the thermal stability of the spinning oil meets the requirements of the carbonization production process based on the thermogravimetric properties obtained from the thermogravimetric test.

[0008] Further, in step S1, the pasteless carbon wire is a PAN-based pasteless carbon wire with a diameter of 5~15μm and a length of 5~10cm; The environmental conditions for the oiling treatment are: temperature 20~25℃, relative humidity 40%~60%, and drying time 1~2 hours.

[0009] Furthermore, in step 2, the segmented temperature ranges of the actual carbonization production process of the carbon fiber include a pre-oxidation segment of 200~400℃, a low-temperature carbonization segment of 400~800℃, and a high-temperature carbonization segment of 800~1200℃. For the above segmented temperature ranges, the TGA test program sets the heating rate to 5~200℃ / min.

[0010] Furthermore, in step S2, the test atmosphere is nitrogen or air, and the atmosphere flow rate is 20~50mL / min, which is consistent with the protective atmosphere in the actual carbonization production of carbon fiber.

[0011] Furthermore, in step S3, the preset length of the sample is 0.5~1cm, the sample tray is made of ceramic material, the sample volume is 1~10mg, and the sample tray is dried at high temperature to remove impurities before testing.

[0012] Furthermore, PAN-based non-slurry carbon filaments with a diameter of 8μm and a length of 8cm were selected as carriers. The silicone oil was uniformly coated on the surface of the non-slurry carbon filaments using an dip-coating method, and the oiling rate was controlled at 1.5%. The samples were then dried for 1.5 hours at a temperature of 22℃ and a relative humidity of 50% to obtain oiled non-slurry carbon filament samples. Based on the actual carbonization production process of carbon fiber, the TGA test procedure was set in stages: the temperature range of the pre-oxidation stage was 200~400℃, with a heating rate of 10℃ / min; the temperature range of the low-temperature carbonization stage was 400~800℃, with a heating rate of 10℃ / min; the temperature range of the high-temperature carbonization stage was 800~1200℃, with a heating rate of 10℃ / min; the test atmosphere was nitrogen, with an atmosphere flow rate of 30mL / min. Cut the oiled, paste-free carbon filament sample into 0.8cm long segments, place them in a ceramic sample dish, and start the thermogravimetric analysis (TGA) test.

[0013] Furthermore, PAN-based pasteless carbon filaments with a diameter of 12μm and a length of 6cm were selected as carriers. Silicone oil was uniformly coated on the surface of the pasteless carbon filaments using a spraying method, and the oiling rate was controlled at 2.5%. The filaments were then dried for 1 hour at a temperature of 24℃ and a relative humidity of 45% to obtain oiled pasteless carbon filament samples. Based on the actual carbonization production process of carbon fiber, the TGA test procedure was set in stages: the temperature range of the pre-oxidation stage was 200~400℃, with a heating rate of 8℃ / min; the temperature range of the low-temperature carbonization stage was 400~800℃, with a heating rate of 12℃ / min; the temperature range of the high-temperature carbonization stage was 800~1200℃, with a heating rate of 15℃ / min; the test atmosphere was nitrogen, and the atmosphere flow rate was 40mL / min. Cut the oiled, paste-free carbon filament sample into 0.6cm long segments, place them in a ceramic sample dish, and start the thermogravimetric analysis (TGA) test.

[0014] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages: Using slurry-free carbon fiber as a carrier for spinning oil is completely consistent with the application scenario of oil in actual carbon fiber production. This avoids the problem of test results being out of touch with actual applications caused by testing pure oil or slurry-containing carbon fiber in existing technologies. It can accurately reflect the thermogravimetric change law of spinning oil in the actual carbonization process. Based on the segmented temperatures, heating rates, and atmospheric conditions of the actual carbonization production process of carbon fiber, a customized TGA test program was developed to simulate the environment of different carbonization stages. The parameters obtained from the test, such as thermal decomposition temperature and mass loss rate, are more valuable for reference. This experimental method has clear steps, strong repeatability, no need for complicated sample pretreatment, and high testing efficiency. It can provide fast and accurate data support for the selection of spinning oil and the optimization of oiling process, and reduce product quality problems caused by improper selection of oil in carbon fiber production.

[0015] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a flowchart of the test steps for the thermogravimetric properties of the spinning oil agent of the present invention; Detailed Implementation

[0017] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0018] like Figure 1 As shown, this invention provides a test method for verifying the thermogravimetric properties of spinning oils using a simulated carbonization process, comprising the following steps: Step S1, oiling treatment of pulpless carbon fiber: Select pulpless carbon fiber as carrier, prepare spinning oil with the same solid content, and use dip coating or spray coating to evenly coat the spinning oil on the surface of pulpless carbon fiber, control the oiling rate to 0.5%~3.0%, and obtain oiled pulpless carbon fiber sample after drying.

[0019] Using slurry-free carbon fiber as the carrier of spinning oil is completely consistent with the application scenario of oil in actual carbon fiber production. This avoids the problem of test results being out of touch with actual applications caused by testing pure oil or slurry-containing carbon fiber in existing technologies. It can accurately reflect the thermogravimetric change law of spinning oil in the actual carbonization process.

[0020] Step S2: Design a corresponding TGA test program based on the actual carbonization production process of carbon fiber: Design a corresponding TGA test program based on the segmented temperature range, heating rate and atmosphere conditions of the actual carbonization production process of carbon fiber. The temperature range and heating rate of the TGA test program are consistent with the carbonization production process, and the test atmosphere is matched with the carbonization atmosphere.

[0021] Based on the segmented temperatures, heating rates, and atmospheric conditions of the actual carbonization production process of carbon fiber, a customized TGA test program was developed to simulate the environment at different carbonization stages. The parameters obtained from the test, such as thermal decomposition temperature and mass loss rate, are more valuable for reference and can be directly used to guide the selection of spinning oils.

[0022] Step S3: Perform thermogravimetric analysis using a TGA tester: Cut the oiled, slurry-free carbon fiber sample into a preset length, place it in the sample tray of the TGA tester, set the test parameters to be consistent with the designed TGA program, start the tester to perform thermogravimetric analysis, and analyze and record the sample's mass loss rate, thermal decomposition temperature, and mass loss rate.

[0023] Step S4: Verify the thermogravimetric properties of the spinning oil based on the test results: Based on the thermogravimetric properties parameters obtained from the TGA test, determine whether the thermal stability of the spinning oil meets the requirements of the carbonization production process, and complete the verification of the thermogravimetric properties of the spinning oil.

[0024] The test method of this invention has clear steps and strong repeatability. It does not require complicated sample pretreatment (such as oil extraction and concentration), and has high testing efficiency. It can provide fast and accurate data support for the selection of spinning oil and the optimization of oiling process, and reduce product quality problems caused by improper selection of oil in carbon fiber production.

[0025] By combining the pasteless carbon fiber carrier with the TGA program of the bonding carbonization process, the core technical defects of the existing spinning oil thermogravimetric testing are solved, and the technical gap of in-situ thermogravimetric testing after oiling of pasteless carbon fiber is filled.

[0026] In step S1, the pulpless carbon fiber is a PAN-based pulpless carbon fiber with a diameter of 5-15 μm and a length of 5-10 cm. The surface is free of impurities and damage. Selecting this specification of pulpless carbon fiber is consistent with the specifications of the intermediates used in actual carbon fiber production, ensuring the authenticity of the test scenario. The environmental conditions for the oiling treatment in step S1 are: temperature 20-25℃, relative humidity 40%-60%, and drying time 1-2 hours. During the drying process, the sample should be protected from contamination with impurities. These environmental conditions avoid the influence of temperature and humidity on the uniformity of the oil coating and the drying effect, ensuring the consistency of the oiled pulpless carbon fiber samples.

[0027] In step 2, the segmented temperature range of the actual carbonization production process of the carbon fiber includes a pre-oxidation stage of 200~400℃, a low-temperature carbonization stage of 400~800℃, and a high-temperature carbonization stage of 800~1200℃. The corresponding TGA test program is set with a heating rate of 5~200℃ / min according to the above segmentation. This segmentation setting is completely matched with the actual carbonization process and can accurately simulate the thermal decomposition behavior of the oil at different carbonization stages.

[0028] Furthermore, in step S2, the test atmosphere is nitrogen or air, and the atmosphere flow rate is 20~50mL / min, which is consistent with the protective atmosphere in the actual carbonization production of carbon fiber, so as to avoid the interference of oxygen on the test results and ensure the accuracy of the test data.

[0029] Based on the segmented temperatures, heating rates, and atmospheric conditions of the actual carbonization production process of carbon fiber, a customized TGA test program was developed to simulate the environment at different carbonization stages. The parameters obtained from the test, such as thermal decomposition temperature and mass loss rate, are more valuable for reference and can be directly used to guide the selection of spinning oils. Furthermore, in step S3, the preset length of the sample is 0.5~1cm, the sample tray is made of ceramic material, the sample volume is 1~10mg, and the sample tray is dried at high temperature to remove impurities before testing. The ceramic sample tray is resistant to high temperature and has good chemical stability, which can prevent the sample tray from reacting with the sample. At the same time, the sample volume is controlled to ensure the sensitivity of the thermogravimetric test.

[0030] Specifically, for PAN-based pasteless carbon filaments with a diameter of 8μm and a length of 8cm, the specific implementation method is as follows: PAN-based pasteless carbon wire (8μm in diameter, 8cm in length, with no impurities or damage on the surface) was selected as the carrier. A silicone-free oil was uniformly coated onto the surface of the carbon wire using a dip-coating method, with the oil application rate controlled at 1.5%. The wire was then air-dried for 1.5 hours at 22℃ and 50% relative humidity to obtain the oiled pasteless carbon wire sample. (Step S1) Corresponding to the above-mentioned PAN-based pulpless carbon fiber, based on the actual carbonization production process of carbon fiber, the TGA test procedure was set in segments: pre-oxidation section 200~400℃, heating rate 10℃ / min; low-temperature carbonization section 400~800℃, heating rate 10℃ / min; high-temperature carbonization section 800~1200℃, heating rate 10℃ / min; the test atmosphere was nitrogen, and the atmosphere flow rate was 30mL / min. (Step S2) Cut the oiled, slurry-free carbon filament sample into 0.8 cm long segments. Select a ceramic sample dish (pre-dried at 800℃ for 2 hours to remove impurities), place 8 mg of sample in the sample dish, put the sample dish into the TGA analyzer, set the test parameters to be consistent with the TGA program designed above, start the analyzer to perform thermogravimetric analysis, and analyze and record the sample's mass loss rate, thermal decomposition temperature, and mass loss rate. (Step S3) According to TGA test results, the mass loss rate of this silicone-free agent was 8.2% in the pre-oxidation stage (200~400℃), and 25.3% in the low-temperature carbonization stage (400~800℃). The thermal decomposition temperature was 385℃. (Step S4) The specific implementation method for PAN-based pasteless carbon filaments with a diameter of 12μm and a length of 6cm is as follows: PAN-based pasteless carbon wire (12μm in diameter, 6cm in length, with no impurities or damage on the surface) was selected as the carrier. A silicone oil was uniformly coated onto the surface of the pasteless carbon wire using a spraying method, with the oil application rate controlled at 2.5%. The wire was then air-dried for 1 hour at 24℃ and 45% relative humidity to obtain the oiled pasteless carbon wire sample. (Step S1) Based on the actual carbonization production process of carbon fiber, the TGA test procedure was set in stages: pre-oxidation stage 200~400℃, heating rate 8℃ / min; low-temperature carbonization stage 400~800℃, heating rate 12℃ / min; high-temperature carbonization stage 800~1200℃, heating rate 15℃ / min; the test atmosphere was nitrogen, and the atmosphere flow rate was 40mL / min. (Step S2) Cut the oiled, slurry-free carbon filament sample into 0.6 cm long segments. Select an oxygen ceramic sample tray (pre-dried at 800℃ for 2 hours to remove impurities), place 6 mg of sample in the tray, and put the tray into the TGA analyzer. Set the test parameters to be consistent with the TGA program designed above, start the analyzer to perform thermogravimetric analysis, and record the sample's mass loss rate, thermal decomposition temperature, and mass loss rate in real time. (Step S3) According to TGA test results, the mass loss rate of this silicone oil agent was 9.7% in the pre-oxidation stage (200~400℃), and 28.9% in the low-temperature carbonization stage (400~800℃). The thermal decomposition temperature was 362℃. (Step S4) For the aforementioned PAN-based pulpless carbon fiber with a diameter of 8μm and a length of 8cm, if existing technology is used to test the thermogravimetric properties of the spinning oil, a pure silicone-free oil is selected as the test sample. A single heating rate (10℃ / min) is used to raise the temperature from room temperature to 1200℃, with air as the test atmosphere, and other test conditions consistent with Example 1. The test results show that the thermal decomposition temperature of this silicone-free oil is 320℃, and the mass loss rate reaches 45% at 400℃, which is significantly different from the test results of Example 1. Furthermore, the test results cannot reflect the true thermal stability of the oil during the actual carbonization process and cannot be used to guide production selection, further demonstrating the superiority of the method of the present invention.

[0031] The above description provides examples of the preferred embodiments of the present invention. Parts not detailed herein are common knowledge to those skilled in the art. The scope of protection of the present invention is determined by the claims. Any equivalent modifications based on the technical teachings of the present invention are also within the scope of protection of the present invention.

Claims

1. A test method for verifying the thermogravimetric properties of spinning oils using a simulated carbonization process, characterized in that: Includes the following steps: Step S1, oiling treatment of pulpless carbon fiber; uniformly coat the surface of pulpless carbon fiber with spinning oil, and obtain oiled pulpless carbon fiber sample after drying. Step S2: Design the corresponding TGA test program based on the actual carbonization production process of carbon fiber. Based on the segmented temperature ranges, heating rates, and atmospheric conditions of the actual carbonization production process of carbon fiber, a corresponding TGA test procedure is designed. Step S3: Perform thermogravimetric analysis using a TGA tester; cut the oiled, paste-free carbon fiber sample into a preset length and start the tester to perform the thermogravimetric analysis. Step S4: Verify the thermogravimetric properties of the spinning oil based on the test results; Based on the thermogravimetric properties obtained from the thermogravimetric analysis, determine whether the thermal stability of the spinning oil meets the requirements of the carbonization production process.

2. The test method for verifying the thermogravimetric properties of spinning oils using a simulated carbonization process as described in claim 1, characterized in that: In step S1, the pasteless carbon wire is a PAN-based pasteless carbon wire with a diameter of 5~15μm and a length of 5~10cm; The environmental conditions for the oiling treatment are: temperature 20~25℃, relative humidity 40%~60%, and drying time 1~2 hours.

3. The test method for verifying the thermogravimetric properties of spinning oils using a simulated carbonization process as described in claim 2, characterized in that: In step 2, the segmented temperature ranges of the actual carbonization production process of the carbon fiber include a pre-oxidation segment of 200~400℃, a low-temperature carbonization segment of 400~800℃, and a high-temperature carbonization segment of 800~1200℃. For the above segmented temperature ranges, the TGA test program sets the heating rate to 5~200℃ / min.

4. The test method for verifying the thermogravimetric properties of spinning oils using a simulated carbonization process as described in claim 3, characterized in that: In step S2, the test atmosphere is nitrogen or air, and the atmosphere flow rate is 20~50mL / min, which is consistent with the protective atmosphere in the actual carbonization production of carbon fiber.

5. The test method for verifying the thermogravimetric properties of spinning oils using a simulated carbonization process as described in claim 4, characterized in that: In step S3, the preset length of the sample is 0.5~1cm, the sample tray is made of ceramic material, the sample volume is 1~10mg, and the sample tray is dried at high temperature to remove impurities before testing.

6. The test method for verifying the thermogravimetric properties of spinning oils using a simulated carbonization process as described in claim 5, characterized in that: PAN-based non-slurry carbon filaments with a diameter of 8μm and a length of 8cm were selected as carriers. The non-silicone oil was uniformly coated on the surface of the non-slurry carbon filaments using the dip-coating method, and the oiling rate was controlled at 1.5%. The samples were dried for 1.5 hours at a temperature of 22℃ and a relative humidity of 50% to obtain oiled non-slurry carbon filament samples. Based on the actual carbonization production process of carbon fiber, the TGA test procedure was set in stages: the temperature range of the pre-oxidation stage was 200~400℃, with a heating rate of 10℃ / min; the temperature range of the low-temperature carbonization stage was 400~800℃, with a heating rate of 10℃ / min; the temperature range of the high-temperature carbonization stage was 800~1200℃, with a heating rate of 10℃ / min; the test atmosphere was nitrogen, with an atmosphere flow rate of 30mL / min. Cut the oiled, paste-free carbon filament sample into 0.8cm long segments, place them in a ceramic sample dish, and start the thermogravimetric analysis (TGA) test.

7. The test method for verifying the thermogravimetric properties of spinning oils using a simulated carbonization process as described in claim 5, characterized in that: PAN-based pasteless carbon wire with a diameter of 12μm and a length of 6cm was selected as the carrier. The silicone oil was uniformly coated on the surface of the pasteless carbon wire by spraying, and the oiling rate was controlled at 2.5%. The sample of oiled pasteless carbon wire was obtained by air drying for 1 hour at a temperature of 24℃ and a relative humidity of 45%. Based on the actual carbonization production process of carbon fiber, the TGA test procedure was set in stages: the temperature range of the pre-oxidation stage was 200~400℃, with a heating rate of 8℃ / min; the temperature range of the low-temperature carbonization stage was 400~800℃, with a heating rate of 12℃ / min; the temperature range of the high-temperature carbonization stage was 800~1200℃, with a heating rate of 15℃ / min; the test atmosphere was nitrogen, and the atmosphere flow rate was 40mL / min. Cut the oiled, paste-free carbon filament sample into 0.6cm long segments, place them in a ceramic sample dish, and start the thermogravimetric analysis (TGA) test.

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