Preparation method of self-emulsifying wet spinning oil for raw filaments and preparation method of high-uniformity carbon fibers

Abstract

The application discloses a preparation method of a self-emulsifying type wet spinning raw silk oil agent and a preparation method of high-uniformity carbon fibers, and belongs to the technical field of carbon fibers. In the application, polyglycerol and epsilon-caprolactone are catalytically prepared into PG-PCL; then the PG-PCL is reacted with acrylate to obtain acrylated PG-PCL; finally, the PG-PCL, the acrylated PG-PCL and perfluoropolyether acrylate are uniformly dissolved in acetone; then carboxylated cellulose nanocrystals and iron phthalocyanine are added and high-speed shearing emulsification is carried out, and water is gradually added to form a nanoemulsion; and the high-uniformity carbon fibers are obtained by combining a low-temperature preparation method of the carbon fibers. The method synchronously solves the problems of emulsion stability, fiber uniformity and carbonization compatibility, shortens a production cycle, is suitable for high-end fields such as aerospace and new energy vehicles, and has the advantages of high performance and green manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of carbon fiber technology, specifically relating to a method for preparing a self-emulsifying wet spinning precursor oil and a method for preparing highly uniform carbon fibers. Background Technology

[0002] Carbon fiber, due to its high strength, high modulus, and excellent high-temperature resistance, is widely used in aerospace, new energy vehicles, and other fields. Wet spinning, as the mainstream process for preparing carbon fiber precursor, hinges on the selection and coating process of the oiling agent. The oiling agent not only needs to provide lubrication and antistatic functions during spinning but also needs to work synergistically with the fiber in the subsequent carbonization stage to ensure the final carbon fiber's structural density and mechanical properties. However, existing technologies still face the following key bottlenecks:

[0003] Currently, wet spinning oils mostly use small-molecule emulsifiers such as Span and Tween to construct emulsion systems. While these emulsifiers can reduce the oil-water interfacial tension, they also have problems such as high critical micelle concentration (CMC) and easy stratification during storage (centrifugal stability <70%). More seriously, emulsifier residues generate ash during carbonization, leading to increased porosity of carbon fibers and limiting the improvement of their mechanical properties.

[0004] To improve the surface lubricity of fibers, existing technologies often add silicone oil as a film-forming agent. However, silicone oil decomposes into inorganic substances during high-temperature carbonization, which clog fiber pores and are difficult to completely remove through post-processing, resulting in the tensile strength of carbon fibers being limited to 4.0-4.5 GPa.

[0005] Therefore, there is an urgent need to develop a novel oil system that combines self-emulsification stability, uniform coating ability, and carbonization synergistic enhancement effect. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method for preparing a self-emulsifying wet spinning precursor oil and a method for preparing highly uniform carbon fibers.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a self-emulsifying oiling agent for wet spinning precursor yarn, comprising the following preparation steps: 1) Under nitrogen protection, polyglycerol, ε-caprolactone, and stannous octoate were dissolved together in toluene, mixed thoroughly, and then heated to react and obtain PG-PCL; 2) Dissolve PG-PCL in DCM, cool to 0°C in an ice bath, slowly add acryloyl chloride, and simultaneously add triethanolamine. After the addition is complete, raise the temperature to react and obtain acrylated PG-PCL. 3) Dissolve PG-PCL, acrylated PG-PCL, and perfluoropolyether acrylate in acetone and mix thoroughly; then add carboxylated cellulose nanocrystals and iron phthalocyanine, emulsify at high speed, and gradually add water to form a nanoemulsion.

[0008] Further, in step 1), the mass ratio of polyglycerol, ε-caprolactone, stannous octanoate, and toluene is 1:(8-12):0.5:(30-40).

[0009] This invention utilizes a hyperbranched polymer with polyglycerol-polycaprolactone (PG-PCL) as its backbone. Its three-dimensional dendritic structure forms self-supporting nanomicelles through intramolecular microphase separation, eliminating the need for external emulsifiers and significantly improving emulsion stability.

[0010] Furthermore, in step 1), the temperature of the heating reaction is 120-140℃, and the reaction time is 18-24h.

[0011] Further, in step 2), the mass ratio of PG-PCL, DCM, acryloyl chloride, and triethanolamine is 20:200:(10-30):20.

[0012] The present invention introduces acrylated PG-PCL into the oil, and after spinning, micelle crosslinking is triggered by ultraviolet irradiation to form a nanoscale three-dimensional network coating to prevent oil migration.

[0013] Furthermore, in step 2), the temperature of the heating reaction is 23-26℃, and the reaction time is 8-16h.

[0014] Further, in step 3), the mass ratio of PG-PCL, acrylated PG-PCL, perfluoropolyether acrylate, acetone, carboxylated cellulose nanocrystals, iron phthalocyanine, and water is (40-50):20:(1-3):100:1:0.5:(20-40).

[0015] This invention adds surface-modified cellulose nanocrystals (CNC, diameter 5 nm, aspect ratio > 50) as a scale to guide the oil agent to self-assemble in an orderly manner along the fiber axis in the coagulation bath, thereby eliminating surface wrinkles. The oil is infused with a temperature-responsive fluorocarbon surfactant, perfluoropolyether acrylate, which triggers a change in surface tension gradient through solidification temperature difference, thereby achieving a self-spreading effect on the fiber surface and increasing the coverage to 99.5%.

[0016] Iron phthalocyanine, a transition metal phthalocyanine complex loaded with oil, catalyzes the orientation and arrangement of microcrystals inside the fiber during carbonization, thereby reducing the graphitization temperature and increasing the modulus of the carbon fiber.

[0017] Furthermore, in step 3), the high-speed shear emulsification rotation speed is 12000 rpm and the time is 30 min.

[0018] This invention also provides a method for preparing highly uniform carbon fibers, comprising the following preparation steps: S1. The pH of the nanoemulsion was adjusted to 6.5 with 0.1 M NaOH, and no stratification was observed after standing for 24 hours; S2. Fill the impregnation tank with nanoemulsion and then pass the carbon fiber precursor through the impregnation tank at a speed of 20 m / min; S3. The original fibers coated with nanoemulsion are placed in a 5℃ coagulation zone for coagulation. S4. After solidification, transfer to the UV curing area and cure at 365 nm for 10 seconds; S5. After curing, transfer to the carbonization zone and heat to 200-300℃ at a rate of 2℃ / min for 20min for pre-oxidation; then heat to 1000-1200℃ and carbonize for 30min to obtain carbon fiber.

[0019] Furthermore, in step S2, the temperature of the impregnation tank is controlled at 35°C, and the amount of oil adhering is controlled at 7-8 wt%.

[0020] It contains at least the following beneficial technical effects: This invention replaces traditional silicone oil and emulsifiers with a hyperbranched polyglycerol-polycaprolactone (PG-PCL) self-emulsifying system. Combined with a temperature-responsive perfluoropolyether surfactant and carboxylated cellulose nanocrystal (CNC) template guidance, it achieves nanoscale uniform coating on the surface of carbon fiber precursor fibers, and locks the coating structure through ultraviolet light crosslinking. This method simultaneously solves the problems of emulsion stability, fiber uniformity, and carbonization compatibility, shortens the production cycle, and is suitable for high-end fields such as aerospace and new energy vehicles, combining the advantages of high performance and green manufacturing. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments. The following embodiments are only descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0022] Unless otherwise specified, all reagents used in this invention are commercially available conventional reagents; and all methods used in this invention are conventional methods used in this technical field unless otherwise specified.

[0023] Example 1 A method for preparing highly uniform carbon fibers includes the following preparation steps: 1) Under nitrogen protection, polyglycerol, ε-caprolactone, and stannous octoate were dissolved together in toluene and mixed evenly. The mixture was then heated to 130℃ and reacted for 22 hours to obtain PG-PCL. The mass ratio of polyglycerol, ε-caprolactone, stannous octoate, and toluene was 1:10:0.5:35.

[0024] 2) Dissolve PG-PCL in DCM, cool to 0℃ in an ice bath, slowly add acryloyl chloride and triethanolamine dropwise, and after the addition is complete, heat to 25℃ and react for 12h to obtain acrylated PG-PCL; wherein the mass ratio of PG-PCL, DCM, acryloyl chloride and triethanolamine is 20:200:20:20.

[0025] 3) Dissolve PG-PCL, acrylated PG-PCL, and perfluoropolyether acrylate in acetone and mix thoroughly; then add carboxylated cellulose nanocrystals and iron phthalocyanine, and emulsify at high speed of 12000 rpm for 30 min, gradually adding water to form a nanoemulsion; wherein the mass ratio of PG-PCL, acrylated PG-PCL, perfluoropolyether acrylate, acetone, carboxylated cellulose nanocrystals, iron phthalocyanine, and water is 45:20:2:100:1:0.5:30.

[0026] 4) Adjust the pH of the nanoemulsion to 6.5 with 0.1 M NaOH and let it stand for 24 hours without stratification.

[0027] 5) Fill the impregnation tank with nanoemulsion and then pass the carbon fiber precursor through the impregnation tank at a speed of 20 m / min; control the temperature of the impregnation tank at 35℃ and control the amount of oil adhering to 7 wt%.

[0028] 6) The original fibers coated with nanoemulsion are placed in a 5℃ coagulation zone for coagulation.

[0029] 7) After solidification, transfer to the UV curing area and cure at 365 nm for 10 seconds.

[0030] 8) After curing, transfer to the carbonization zone and heat to 220℃ at a rate of 2℃ / min for 20min for pre-oxidation; then heat to 1050℃ and carbonize for 30min to obtain carbon fiber.

[0031] Example 2 A method for preparing highly uniform carbon fibers includes the following preparation steps: 1) Under nitrogen protection, polyglycerol, ε-caprolactone, and stannous octoate were dissolved together in toluene and mixed evenly. The mixture was then heated to 120℃ and reacted for 18h to obtain PG-PCL. The mass ratio of polyglycerol, ε-caprolactone, stannous octoate, and toluene was 1:8:0.5:30.

[0032] 2) Dissolve PG-PCL in DCM, cool to 0℃ in an ice bath, slowly add acryloyl chloride and triethanolamine dropwise, and after the addition is complete, heat to 23℃ and react for 8 hours to obtain acrylated PG-PCL; wherein the mass ratio of PG-PCL, DCM, acryloyl chloride and triethanolamine is 20:200:10:20.

[0033] 3) Dissolve PG-PCL, acrylated PG-PCL, and perfluoropolyether acrylate in acetone and mix thoroughly; then add carboxylated cellulose nanocrystals and iron phthalocyanine, and emulsify at high speed of 12000 rpm for 30 min, gradually adding water to form a nanoemulsion; wherein the mass ratio of PG-PCL, acrylated PG-PCL, perfluoropolyether acrylate, acetone, carboxylated cellulose nanocrystals, iron phthalocyanine, and water is 40:20:1:100:1:0.5:20.

[0034] 4) Adjust the pH of the nanoemulsion to 6.5 with 0.1 M NaOH and let it stand for 24 hours without stratification.

[0035] 5) Fill the impregnation tank with nanoemulsion and then pass the carbon fiber precursor through the impregnation tank at a speed of 20 m / min; control the temperature of the impregnation tank at 35℃ and control the amount of oil adhering to 8 wt%.

[0036] 6) The original fibers coated with nanoemulsion are placed in a 5℃ coagulation zone for coagulation.

[0037] 7) After solidification, transfer to the UV curing area and cure at 365 nm for 10 seconds.

[0038] 8) After curing, transfer to the carbonization zone and heat to 200℃ at a rate of 2℃ / min for 20min for pre-oxidation; then heat to 1000℃ and carbonize for 30min to obtain carbon fiber.

[0039] Example 3 A method for preparing highly uniform carbon fibers includes the following preparation steps: 1) Under nitrogen protection, polyglycerol, ε-caprolactone, and stannous octoate were dissolved together in toluene and mixed evenly. The mixture was then heated to 140℃ and reacted for 24 hours to obtain PG-PCL. The mass ratio of polyglycerol, ε-caprolactone, stannous octoate, and toluene was 1:12:0.5:40.

[0040] 2) Dissolve PG-PCL in DCM, cool to 0℃ in an ice bath, slowly add acryloyl chloride and triethanolamine dropwise, and after the addition is complete, heat to 26℃ and react for 16h to obtain acrylated PG-PCL; wherein the mass ratio of PG-PCL, DCM, acryloyl chloride and triethanolamine is 20:200:30:20.

[0041] 3) Dissolve PG-PCL, acrylated PG-PCL, and perfluoropolyether acrylate in acetone and mix thoroughly; then add carboxylated cellulose nanocrystals and iron phthalocyanine, and emulsify at high speed of 12000 rpm for 30 min, gradually adding water to form a nanoemulsion; wherein the mass ratio of PG-PCL, acrylated PG-PCL, perfluoropolyether acrylate, acetone, carboxylated cellulose nanocrystals, iron phthalocyanine, and water is 50:20:3:100:1:0.5:40.

[0042] 4) Adjust the pH of the nanoemulsion to 6.5 with 0.1 M NaOH and let it stand for 24 hours without stratification.

[0043] 5) Fill the impregnation tank with nanoemulsion and then pass the carbon fiber precursor through the impregnation tank at a speed of 20 m / min; control the temperature of the impregnation tank at 35℃ and control the amount of oil adhering to 7 wt%.

[0044] 6) The original fibers coated with nanoemulsion are placed in a 5℃ coagulation zone for coagulation.

[0045] 7) After solidification, transfer to the UV curing area and cure at 365 nm for 10 seconds.

[0046] 8) After curing, transfer to the carbonization zone and heat to 300℃ at a rate of 2℃ / min for 20min for pre-oxidation; then heat to 1200℃ and carbonize for 30min to obtain carbon fiber.

[0047] Experimental Example 1 1. Emulsion stability test, the test results are shown in Table 1.

[0048] Table 1

[0049] 2. Fiber surface uniformity test.

[0050] Detection method: Surface roughness was measured using atomic force microscopy and then automatically calculated using computer software. Coverage Scanning Electron Microscopy (SEM): Backscattered Electron (BSE) mode distinguishes between oil and fiber surfaces. ImageJ software was used to set thresholds, marking oil areas (dark) as black and fiber substrates (bright) as white; Coverage = Number of black pixels / Total number of pixels 100%.

[0051] The results are shown in Table 2. Table 2

[0052] 3. Testing of carbon fiber mechanical properties Test standard: GB / T 31290-2015, test results are shown in Table 3.

[0053] Table 3

[0054] According to the above tests, the carbon fiber oil prepared by the present invention does not contain silicone oil, has self-emulsifying properties and does not require the use of additional emulsifiers, and has high coverage uniformity. At the same time, the resulting carbon fiber has good mechanical properties.

[0055] Although the present invention has been described in detail above, it is not limited thereto. Those skilled in the art can make modifications based on the principles of the present invention. Therefore, all modifications made in accordance with the principles of the present invention should be understood as falling within the protection scope of the present invention.

Claims

1. A method for preparing a self-emulsifying oiling agent for wet spinning precursor yarn, comprising the following preparation steps: 1) Under nitrogen protection, polyglycerol, ε-caprolactone, and stannous octoate were dissolved together in toluene, mixed thoroughly, and then heated to react and obtain PG-PCL; 2) Dissolve PG-PCL in DCM, cool to 0°C in an ice bath, slowly add acryloyl chloride, and simultaneously add triethanolamine. After the addition is complete, raise the temperature to react and obtain acrylated PG-PCL. 3) Dissolve PG-PCL, acrylated PG-PCL, and perfluoropolyether acrylate in acetone and mix thoroughly; then add carboxylated cellulose nanocrystals and iron phthalocyanine, emulsify at high speed, and gradually add water to form a nanoemulsion.

2. The preparation method according to claim 1, characterized in that, In step 1), the mass ratio of polyglycerol, ε-caprolactone, stannous octanoate, and toluene is 1:(8-12):0.5:(30-40).

3. The preparation method according to claim 1, characterized in that, The temperature of the heating reaction in step 1) is 120-140℃, and the reaction time is 18-24h.

4. The preparation method according to claim 1, characterized in that, In step 2), the mass ratio of PG-PCL, DCM, acryloyl chloride, and triethanolamine is 20:200:(10-30):

20.

5. The preparation method according to claim 1, characterized in that, In step 2), the temperature for the heating reaction is 23-26℃, and the reaction time is 8-16h.

6. The preparation method according to claim 1, characterized in that, In step 3), the mass ratio of PG-PCL, acrylated PG-PCL, perfluoropolyether acrylate, acetone, carboxylated cellulose nanocrystals, iron phthalocyanine, and water is (40-50):20:(1-3):100:1:0.5:(20-40).

7. The preparation method according to claim 1, characterized in that, In step 3), the high-speed shear emulsification rotation speed is 12000 rpm and the time is 30 min.

8. A method for preparing highly uniform carbon fibers, characterized in that, The preparation steps include the following: S1. The nanoemulsion described in claim 1 is adjusted to pH 6.5 with 0.1 M NaOH and allowed to stand for 24 hours without separation; S2. Fill the impregnation tank with nanoemulsion and then pass the carbon fiber precursor through the impregnation tank at a speed of 20 m / min; S3. The original fibers coated with nanoemulsion are placed in a 5℃ coagulation zone for coagulation. S4. After solidification, transfer to the UV curing area and cure at 365 nm for 10 seconds; S5. After curing, transfer to the carbonization zone and heat to 200-300℃ at a rate of 2℃ / min for 20min for pre-oxidation; then heat to 1000-1200℃ and carbonize for 30min to obtain carbon fiber.

9. The preparation method according to claim 8, characterized in that, In S2, the temperature of the impregnation tank is controlled at 35°C, and the amount of oil adhering is controlled at 7-8 wt%.

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