A highly wettable and heat-resistant carbon fiber precursor oil, its preparation and application

Abstract

This invention relates to a highly wettable and heat-resistant carbon fiber precursor oil, its preparation, and its application. The components include a silicone oil protectant, a polyether ester, an emulsifier, an antistatic agent, a defoamer, and deionized water. The carbon fiber precursor oil of this invention exhibits excellent lubricity, heat resistance, and film-forming properties. Simultaneously, the oil possesses high wettability, resulting in excellent fiber wetting, effectively protecting the fiber, reducing ash content, and improving the performance of the carbon fiber.

Description

Technical Field

[0001] This invention belongs to the field of precursor fiber oiling agents, and specifically relates to a highly wettable and heat-resistant carbon fiber precursor fiber oiling agent and its preparation and application. Background Technology

[0002] Carbon fiber is a fibrous material with excellent properties such as high strength, high modulus, heat and corrosion resistance. It is widely used in aerospace, railway transportation, wind power generation, medical devices, and leisure and entertainment. Among them, polyacrylonitrile-based carbon fiber has the largest market share due to its superior performance and relatively low price.

[0003] Carbon fiber oil is an important auxiliary agent used in the production of carbon fiber precursor, playing a crucial role in the production of high-performance carbon fibers. The carbon fiber oil forms a uniform oil film on the surface of each monofilament, isolating the monofilaments from each other and preventing adhesion and tangling. Due to the softness and self-lubricating properties of the oil film, it also prevents frictional wear between the fiber bundle and the rollers during production. During pre-oxidation, it prevents heat accumulation or overheating, which could lead to localized thermal adhesion or tangling of the monofilaments, thus contributing to the formation of homogeneous fibers. Even during low-temperature carbonization, the oil film continues to protect the fiber surface.

[0004] Most carbon fiber oiling agents use silicone-based agents, primarily modified silicone oils with amino, epoxy, and polyether groups. These agents are formulated with silicone oil, deionized water, and additives. Currently, domestically produced oiling agents have many problems, such as poor heat resistance, poor film-forming properties, and excessively high ash content. Current patents for carbon fiber oiling agents mainly focus on improving their heat resistance and film-forming properties. For example, Chinese patent CN118773778A uses low-molecular-weight polysiloxane and phosphate-modified polysiloxane as the main components to obtain a highly protective carbon fiber oiling agent with self-crosslinking and film-forming properties; Chinese patent CN116657287A introduces phenyl-modified silicone oil into a carbon fiber oiling agent system with amino-polyether-modified silicone oil as the main component, improving the agent's heat resistance. The oiling agents in these patents all improve performance by modifying silicone oils with different functional groups, but only improve one aspect of the agent's performance, and all are short-chain modified silicone oils, resulting in high ash content. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a highly wettable and heat-resistant carbon fiber precursor oil, its preparation and application. The oil of the present invention has excellent wettability, film-forming properties and heat resistance, and provides good protection for the fiber.

[0006] This invention provides a carbon fiber precursor oiling agent, comprising the following components by weight:

[0007] 10-30 parts of silicone oil protectant;

[0008] 10-30 parts of polyether esters;

[0009] 1-5 parts emulsifier;

[0010] 1-5 parts of antistatic agent;

[0011] 1-5 parts of defoamer;

[0012] 60-80 parts deionized water;

[0013] The structural formula of the silicone oil protective agent is:

[0014] ;

[0015] Where a is an integer from 5 to 50, b is an integer from 5 to 50, c is an integer from 20 to 200, d is an integer from 5 to 50, and R is... R3 and R4 are selected from C1 to C2 respectively. 10 Alkyl groups.

[0016] Preferably, the molecular weight of the silicone oil protectant is 5000 to 30000.

[0017] Preferably, the silicone oil protectant is obtained by mixing and reacting phenyl hydrogen silicone oil, unsaturated alcohol ether, solvent and catalyst;

[0018] The unsaturated alcohol ether mentioned above is:

[0019] R3 and R4 are selected from C1 to C2 respectively. 10 Alkyl groups.

[0020] The solvent includes one or more of toluene, isopropanol, dichloromethane, chloroform, methanol, acetone, acetonitrile, and dimethyl sulfoxide; the catalyst is chloroplatinic acid.

[0021] The reaction in the preparation of silicone oil protective agent: under nitrogen protection, pre-activation at 50-70℃ for 1-2 h, reaction at 90-110℃ for 3-6 h, and finally de-oxidation under reduced pressure at 120-150℃.

[0022] Preferably, the preparation of the phenyl hydrogen-containing silicone oil includes: mixing octamethylcyclotetrasiloxane, benzene-containing siloxane, hydrogen-containing siloxane, end-capping agent and catalyst, reacting to obtain phenyl hydrogen-containing silicone oil;

[0023] The benzene-containing siloxane is one or more of octaphenylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, diphenyldimethoxysilane, and diphenyldiethoxysilane; the hydrogen-containing siloxane is one or more of tetramethylcyclotetrasiloxane, polymethylhydrosiloxane, pentamethylcyclopentasiloxane, heptamethyltrisiloxane, and octamethyltrisiloxane.

[0024] The end-capping agent is one or more of hexamethyldisiloxane and tetramethyldisiloxane; the catalyst is concentrated sulfuric acid.

[0025] The reaction in the preparation of phenyl hydrogen silicone oil is carried out under nitrogen protection at 40-70°C for 5-9 hours, and finally depressurized at 150-200°C.

[0026] Preferably, the polyether ester has the following structural formula: Where m is an integer from 1 to 10, and R5 is a integer from C2 to C5. 15 Alkyl groups.

[0027] Preferably, the mass ratio of the silicone oil protectant to the polyether ester is (0.5~6):1, and more preferably, the mass ratio is (0.5~2):1.

[0028] Preferably, the emulsifier includes one or more of nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isomeric alcohol polyoxyethylene ether, polyvinyl alcohol, sodium dodecylbenzene sulfonate, and trihydroxymethane polyoxyethylene ether.

[0029] Preferably, the antistatic agent comprises one or more of polyoxyethylene laurate, polyoxyethylene fatty alcohol phosphate, sorbitan fatty acid ester, dodecyltrimethylammonium chloride, and hexadecyltrimethylammonium sulfonate.

[0030] Preferably, the defoamer includes one or more of diisobutylmethanol, ethylene glycol monostearate, isoamyl alcohol, and trialkylmelamine;

[0031] Preferably, the average particle size of the raw silk oil is 150–300 nm.

[0032] This invention provides a method for preparing any of the carbon fiber precursor oils, comprising:

[0033] Weigh each component according to the mass fraction, mix the silicone oil protectant, polyether ester, emulsifier, antistatic agent, and defoamer, then add deionized water and reverse the phase to form an emulsion, thus obtaining the carbon fiber precursor oil.

[0034] This invention provides the application of any of the carbon fiber precursor oiling agents in the preparation of polyacrylonitrile-based carbon fibers.

[0035] Beneficial effects

[0036] The carbon fiber precursor oil of this invention, with silicone oil protectant and polyether esters as the main components, has excellent wettability, film-forming properties and heat resistance, and can effectively protect carbon fiber precursor, improve the mechanical properties of carbon fiber, and reduce the ash content of carbon fiber. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0038] I. The pre-oxidation and carbonization conditions in the examples and comparative examples are as follows:

[0039] Pre-oxidation was carried out in an air atmosphere, and the temperature was maintained at 240℃, 250℃, and 260℃ for 15 min respectively. Carbonization was carried out in a nitrogen atmosphere using a gradient heating method, with the duration of passing through the low-temperature carbonization zone (400℃, 500℃, 600℃, 700℃, 800℃) and the high-temperature carbonization zone (1000℃, 1100℃, 1200℃, 1300℃, 1400℃) both being 2 min.

[0040] II. The testing standards and characterization methods are as follows:

[0041] The particle size of the oil was tested using a particle size analyzer.

[0042] The contact angle was tested using a contact angle measuring instrument to measure the contact angle of the oil on the PAN film;

[0043] The residual heat rate was tested using a thermogravimetric analyzer under nitrogen conditions, and the residual heat rate at 300℃ was used for comparison.

[0044] Mechanical properties were tested according to national standard GB / T 31290-2022, with a clamping distance of 20 mm and a moving speed of 2 mm / min;

[0045] Ash content was tested according to industry standard FZ / T 50044-2018.

[0046] III. Structural formula of the silicone oil protective agent in the examples:

[0047] ,

[0048] Where R is (a): ,or

[0049] (b):

[0050] The structural formula of polyether esters is:

[0051] .

[0052] Example 1

[0053] Highly wettable and heat-resistant carbon fiber precursor oil, comprising the following components by weight:

[0054] 20 parts silicone oil protectant;

[0055] 10 parts of polyether esters;

[0056] 5 parts of fatty alcohol polyoxyethylene ether;

[0057] 3 parts of dodecyltrimethylammonium chloride;

[0058] 2 parts of diisobutylmethanol;

[0059] 60 parts of deionized water.

[0060] The preparation steps of the silicone oil protective agent are as follows:

[0061] (1) Preparation of phenyl hydrogen-containing silicone oil:

[0062] Weigh 106.76 g of octamethylcyclotetrasiloxane, 60 g of diphenyldimethoxysilane, 30 g of polymethylhydrosiloxane, 3.24 g of hexamethyldisiloxane and 3 g of concentrated sulfuric acid, add each component to a reaction vessel and mix evenly. Under nitrogen protection, react at 60°C for 7 h, and then remove the phenyl hydrogen silicone oil by depressurization at 150°C.

[0063] (2) Preparation of silicone oil protective agent:

[0064] Take 200 g of phenyl hydrogen silicone oil, 98.19 g of unsaturated alcohol ether, 74.55 g of isopropanol and 0.018 g of chloroplatinic acid, mix them evenly, pre-activate at 70 °C for 1 h under nitrogen protection, react at 90 °C for 4 h, and then remove the impurities under reduced pressure at 120 °C to obtain the product.

[0065] The R group in the silicone oil protectant is (b), R3 is a C1 alkyl group, R4 is a C2 alkyl group, the molecular weight of the silicone oil protectant is 13682, a is 16, b is 37, c is 25, and d is 36.

[0066] In the polyether esterified compound, m is 2 and R5 is a C5 alkyl group.

[0067] The preparation process and performance testing of the oil are as follows:

[0068] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 194 nm was obtained. The emulsion has excellent stability, a contact angle of 8°, and a thermal residual rate of 98% at 300°C.

[0069] When this oil was applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor was free of fuzz and had good film-forming effect. The carbon fiber obtained after pre-oxidation and carbonization treatment had a tensile strength of 5093 MPa and an ash content of 0.15%.

[0070] Example 2

[0071] Highly wettable and heat-resistant carbon fiber precursor oil, comprising the following components by weight:

[0072] 10 parts silicone oil protectant;

[0073] 20 parts of polyether esters;

[0074] 5 parts of fatty alcohol polyoxyethylene ether;

[0075] 3 parts of dodecyltrimethylammonium chloride;

[0076] 2 parts of diisobutylmethanol;

[0077] 60 parts of deionized water.

[0078] The silicone oil protectant and polyether ester are the same as in Example 1.

[0079] The preparation process and performance testing of the oil are as follows:

[0080] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 173 nm was obtained. The emulsion has excellent stability, a contact angle of 17°, and a thermal residual rate of 94% at 300°C.

[0081] When this oil agent is applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor is free of fuzz and has good film-forming effect. After pre-oxidation and carbonization treatment, the carbon fiber obtained has a tensile strength of 4798 MPa and an ash content of 0.11%.

[0082] Example 3

[0083] Highly wettable and heat-resistant carbon fiber precursor oil, comprising the following components by weight:

[0084] 15 parts silicone oil protectant;

[0085] 15 parts of polyether esters;

[0086] 5 parts of fatty alcohol polyoxyethylene ether;

[0087] 3 parts of dodecyltrimethylammonium chloride;

[0088] 2 parts of diisobutylmethanol;

[0089] 60 parts of deionized water.

[0090] The silicone oil protectant and polyether ester are the same as in Example 1.

[0091] The preparation process and performance testing of the oil are as follows:

[0092] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 185 nm was obtained. The emulsion has excellent stability, a contact angle of 12°, and a thermal residual rate of 96% at 300°C.

[0093] When this oil agent is applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor is free of fuzz and has good film-forming effect. The carbon fiber obtained after pre-oxidation and carbonization treatment has a tensile strength of 4896 MPa and an ash content of 0.13%.

[0094] Example 4

[0095] Highly wettable and heat-resistant carbon fiber precursor oil, with the same mass fractions of each component as in Example 1.

[0096] The preparation steps of the silicone oil protectant are the same as in Example 1, wherein the R group in the silicone oil protectant is (b), R3 is a C3 alkyl group, and R4 is a C6 alkyl group.

[0097] Polyether esters are the same as in Example 1.

[0098] The preparation process and performance testing of the oil are as follows:

[0099] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 197 nm was obtained. The emulsion has excellent stability, a contact angle of 9°, and a thermal residual rate of 98% at 300°C.

[0100] When this oil was applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor was free of fuzz and had good film-forming effect. After pre-oxidation and carbonization treatment, the carbon fiber obtained had a tensile strength of 4932 MPa and an ash content of 0.15%.

[0101] Example 5

[0102] Highly wettable and heat-resistant carbon fiber precursor oil, with the same mass fractions of each component as in Example 1.

[0103] The preparation steps of the silicone oil protectant are the same as in Example 1, wherein the R group in the silicone oil protectant is (b), R3 is a C5 alkyl group, and R4 is a C8 alkyl group.

[0104] The polyether esterification is the same as in Example 1.

[0105] The preparation process and performance testing of the oil are as follows:

[0106] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 193 nm was obtained. The emulsion has excellent stability, a contact angle of 8°, and a thermal residual rate of 98% at 300°C.

[0107] When this oil was applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor was free of fuzz and had good film-forming effect. The carbon fiber obtained after pre-oxidation and carbonization treatment had a tensile strength of 4967 MPa and an ash content of 0.14%.

[0108] Example 6

[0109] Highly wettable and heat-resistant carbon fiber precursor oil, with the same mass fractions of each component as in Example 1.

[0110] The silicone oil protectant is the same as in Example 1.

[0111] In the polyether ester, m is 5 and R5 is C. 10 alkyl.

[0112] The preparation process and performance testing of the oil are as follows:

[0113] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 191 nm was obtained. The emulsion has excellent stability, a contact angle of 8°, and a thermal residual rate of 98% at 300°C.

[0114] When this oil was applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor was free of fuzz and had good film-forming effect. The carbon fiber obtained after pre-oxidation and carbonization treatment had a tensile strength of 4923 MPa and an ash content of 0.15%.

[0115] Example 7

[0116] Highly wettable and heat-resistant carbon fiber precursor oil, with the same mass fractions of each component as in Example 1.

[0117] The silicone oil protectant is the same as in Example 1.

[0118] In the polyether ester, m is 7 and R5 is C. 12 alkyl.

[0119] The preparation process and performance testing of the oil are as follows:

[0120] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 186 nm was obtained. The emulsion has excellent stability, a contact angle of 8°, and a thermal residual rate of 97% at 300°C.

[0121] When this oil agent is applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor is free of fuzz and has good film-forming effect. After pre-oxidation and carbonization treatment, the carbon fiber obtained has a tensile strength of 4931 MPa and an ash content of 0.14%.

[0122] Comparative Example 1

[0123] Highly wettable and heat-resistant carbon fiber precursor oil, comprising the following components by weight:

[0124] 30 parts silicone oil protectant;

[0125] 5 parts of fatty alcohol polyoxyethylene ether;

[0126] 3 parts of dodecyltrimethylammonium chloride;

[0127] 2 parts of diisobutylmethanol;

[0128] 60 parts of deionized water.

[0129] The silicone oil protectant is the same as in Example 1.

[0130] The preparation process and performance testing of the oil are as follows:

[0131] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 267 nm was obtained. The emulsion had good stability, a contact angle of 6°, and a thermal residual rate of 99% at 300°C.

[0132] When this oil was applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor was free of fuzz and had good film-forming effect. The carbon fiber obtained after pre-oxidation and carbonization treatment had a tensile strength of 4827 MPa and an ash content of 0.21%.

[0133] Comparative Example 2

[0134] Highly wettable and heat-resistant carbon fiber precursor oil, with the same mass fractions of each component as in Example 1.

[0135] The preparation steps of the silicone oil protectant are the same as in Example 1, wherein the R group in the silicone oil protectant is (a), R1 is a C1 alkyl group, and R2 is a C2 alkyl group.

[0136] The polyether esterification is the same as in Example 1.

[0137] The preparation process and performance testing of the oil are as follows:

[0138] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 187 nm was obtained. The emulsion exhibited excellent stability, a contact angle of 21°, and a thermal residual rate of 96% at 300°C.

[0139] When this oil agent is applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor is free of fuzz and has good film-forming effect. The carbon fiber obtained after pre-oxidation and carbonization treatment has a tensile strength of 4728 MPa and an ash content of 0.19%.

[0140] Comparative Example 3

[0141] Highly wettable and heat-resistant carbon fiber precursor oil, with the same mass fractions of each component as in Example 1.

[0142] The preparation steps of the silicone oil protectant are the same as in Example 1, wherein the R group in the silicone oil protectant is (a), R1 is a C3 alkyl group, and R2 is a C6 alkyl group.

[0143] The polyether esterification is the same as in Example 1.

[0144] The preparation process and performance testing of the oil are as follows:

[0145] The components, excluding deionized water, were mixed evenly in proportion, and then deionized water was added and stirred for 4 hours. After phase inversion, an emulsion with an average particle size of 184 nm was obtained. The emulsion has excellent stability, a contact angle of 19°, and a thermal residual rate of 97% at 300°C.

[0146] When this oil agent is applied to the preparation of T700 grade carbon fiber precursor, the resulting precursor is free of fuzz and has good film-forming effect. After pre-oxidation and carbonization treatment, the carbon fiber obtained has a tensile strength of 4785 MPa and an ash content of 0.18%.

[0147] In summary, this invention synthesizes a highly wettable and heat-resistant carbon fiber precursor oil, which is composed of silicone oil protectant, polyether ester, emulsifier, antistatic agent, and defoamer.

[0148] Data from Example 1 shows that the carbon fiber precursor oiling agent of the present invention has excellent performance, protecting the fiber and improving its properties. Comparison of data from Examples 1-3 shows that changing the ratio of silicone oil protectant to polyether esters affects fiber performance; more silicone oil protectant results in better wettability and higher heat resistance, but also higher ash content. Comparison of data from Example 1 and Comparative Example 1 shows that polyether esters can improve the emulsification effect of the oiling agent. Comparison of data from Examples 4-5 shows that changing R3 and R4 in group (b) of the silicone oil protectant has no significant effect on fiber performance. Comparison of data from Examples 6-7 shows that changing m and R5 in the polyether ester has no significant effect on oiling agent performance. Comparison of data from Example 1 and Comparative Examples 2-3 shows that replacing the R group in the silicone oil protectant with (a) reduces fiber performance and increases ash content. The present invention proposes a high-wetting and heat-resistant carbon fiber precursor oiling agent, which is of great significance for improving oiling agent wettability, heat resistance, reducing ash content, and enhancing carbon fiber performance.

Claims

1. A carbon fiber precursor oil agent characterized by, The components include, by weight fraction: Silicone protective agent 10-30 parts; Polyether ester 10-30 parts; Emulsifier 1-5 parts; Antistatic agent 1-5 parts; Defoaming agent 1-5 parts; Deionized water 60-80 parts; The structural formula of the silicone protective agent is: ； wherein a is an integer from 5 to 50, b is an integer from 5 to 50, c is an integer from 20 to 200, d is an integer from 5 to 50, R is ; wherein R3, R4are independently selected from C1-C 10 alkyl; The polyether ester has a structural formula of: wherein m is an integer of 1 to 10, R5is a C2to C 15 alkyl group.

2. The carbon fiber precursor oil agent according to claim 1, characterized by, The molecular weight of the silicone protective agent is 5000-30000.

3. The carbon fiber precursor oil agent according to claim 1, characterized by, The silicone oil protective agent is obtained by mixing and reacting phenyl hydrogen-containing silicone oil, unsaturated alcohol ether, solvent and catalyst; wherein the unsaturated alcohol ether is wherein R3 and R4 are respectively selected from C1-C 10 alkyl.

4. The carbon fiber precursor oil agent according to claim 3, characterized by, The solvent includes one or more of toluene, isopropyl alcohol, dichloromethane, chloroform, methanol, acetone, acetonitrile, dimethyl sulfoxide; the catalyst is chloroplatinic acid.

5. The carbon fiber precursor oil agent according to claim 3, wherein The preparation of the phenyl hydrogen-containing silicone oil includes: uniformly mixing octamethylcyclotetrasiloxane, benzene-containing siloxane, hydrogen-containing siloxane, capping agent and catalyst, and reacting to obtain phenyl hydrogen-containing silicone oil; The benzene-containing siloxane is one or more of octaphenylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, diphenyldimethoxysilane, and diphenyldiethoxysilane; the hydrogen-containing siloxane is one or more of tetramethylcyclotetrasiloxane, polymethylhydrosiloxane, pentamethylcyclopentasiloxane, and heptamethyltrisiloxane; The capping agent is one or more of hexamethyldisiloxane and tetramethyldisiloxane; the catalyst is concentrated sulfuric acid.

6. The carbon fiber precursor oil agent according to claim 1, wherein The emulsifier includes one or more of nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isomeric alcohol polyoxyethylene ether, polyvinyl alcohol, sodium dodecylbenzenesulfonate, and trihydroxymethane polyoxyethylene ether; The antistatic agent includes one or more of polyoxyethylene laurate, polyoxyethylene fatty alcohol phosphate ester, sorbitan fatty acid ester, dodecyltrimethylammonium chloride, and cetyltrimethylammonium sulfonate; The defoaming agent includes one or more of diisobutyl carbinol, ethylene glycol monostearate, isoamyl alcohol, and trialkyl melamine; The average particle size of the precursor oil is 150-300 nm.

7. A process for the preparation of the carbon fiber precursor oil agent as claimed in any one of claims 1 to 6, characterized by, The components are weighed by mass fraction, the silicone protective agent, polyether ester, emulsifier, antistatic agent, and defoaming agent are uniformly mixed, then deionized water is added to form an emulsion through phase inversion to obtain a carbon fiber precursor oil.

8. Use of the carbon fiber precursor oil of any one of claims 1-6 in the preparation of polyacrylonitrile-based carbon fiber. ​

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