High-performance polyacrylonitrile carbon fiber precursor oiling agent and preparation method thereof

Abstract

The invention discloses a high-performance polyacrylonitrile carbon fiber precursor oiling agent and a preparation method thereof. The high-performance polyacrylonitrile carbon fiber precursor oiling agent is prepared from the following raw materials in percentage by mass: 5-40% of phenyl silicone oil, 5-60% of polyether / amino polysiloxane block copolymer, 3-35% of quaternary ammonium polysiloxane, 0.01-0.50% of antioxidant, 1-10% of emulsifier and 5-80% of deionized water. The invention provides a brand-new structure, which is easy to be firmly combined with polyacrylonitrile fibers, has good softness and antistatic property, improves the hand feeling of the fibers, and has yellowing resistance; the heat resistance of the polyacrylonitrile fiber is obviously improved, the generation of oil dirt in the drying process is reduced, the roll sticking phenomenon is eliminated, and the conditions of broken filaments, broken filaments, doubled filaments, adhesion and the like of the precursor filaments in the pre-oxidation process are effectively prevented; the radiation resistance, the oxidation stability, the ultraviolet resistance and the chemical resistance are better; and the emulsion has extremely strong hydrophilicity and self-emulsifying ability, and is low in emulsifier consumption and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the field of fine chemicals, and particularly relates to a high-performance polyacrylonitrile carbon fiber precursor sizing agent and a preparation method thereof. Background Art

[0002] The sizing agent for polyacrylonitrile (PAN) carbon fiber precursor is a key auxiliary in the production of carbon fiber. The sizing of PAN precursor is mainly to increase the softness, heat resistance, antistatic ability of the fiber and improve the elongation at break of the precursor; after sizing treatment, the softness and antistatic performance of PAN precursor are significantly enhanced, and the hairiness, flying filaments and broken ends of the precursor are significantly reduced, and the elongation at break of the precursor is significantly improved. It can effectively prevent the melting adhesion or parallelization between single PAN filaments during the pre-oxidation process, without generating hairiness and breakage; the sizing agent directly affects the stable production and quality of carbon fiber precursor, and also has a significant impact on the quality and performance of carbon fiber.

[0003] At present, most of the sizing agents for carbon fiber precursor are silicone-based sizing agents, especially modified sizing agents based on polydimethylsiloxane, which have the advantages of good heat resistance, good flexibility, cohesion, smoothness, low surface tension and self-lubricity, etc., and are widely used in actual production.

[0004] At present, the sizing agents used by domestic enterprises producing high-performance polyacrylonitrile carbon fiber precursors mainly rely on imports, which is also an important reason for the low quality of carbon fiber. The heat resistance of domestic-produced sizing agents is poor, resulting in sticky precursors; the antistatic property of the sizing agent is not good, which easily causes hairiness, winding, breakage, etc. during the production and processing of precursors, seriously restricting the improvement of the quality and production cost of domestic high-performance carbon fiber. There is an urgent need for a sizing agent that can be used in the production of high-performance carbon fiber, which can not only improve the quality but also reduce the cost, and meet the full application of high-performance carbon fiber in the civilian field.

[0005] High-quality sizing agents must have the following characteristics: endowing the fiber with good softness and antistatic performance; endowing an appropriate friction coefficient between fibers, so that the fiber bundle has good cohesion, smoothness, reducing hairiness and broken ends caused by poor cohesion, and preventing the fiber from being damaged by friction with components such as metal and rubber; having excellent heat resistance and not generating smoke during fiber stretching and heat setting processes; not reacting chemically with the fiber bundle.

[0006] Application No.: CN201210440069.7. Inventors: Zhang Ying, Yang Xin, Zhao Xiaojuan, Huang Wei. "Organosilicon spinning finish for preparing polyacrylonitrile-based carbon fiber" is disclosed. Its characteristics are that the organosilicon spinning finish is obtained by uniformly mixing an amino polysiloxane emulsion with a mass concentration in the range of 20 - 40% prepared by mechanical emulsification method and a polydimethylsiloxane emulsion with a mass concentration in the range of 30 - 50% prepared by emulsion polymerization method; for such oil agents prepared by mechanical emulsification, the dosage of emulsifier is large. On the one hand, the use of emulsifier reduces the heat resistance of the oil agent. On the other hand, when the oil agent forms a film on the surface of polyacrylonitrile carbon fiber precursor filaments, it is easy to migrate with the volatilization of water, resulting in uneven film formation on the surface of the precursor filaments; in addition, the oil agent emulsion prepared by using emulsifier is prone to phase separation and has poor storage stability.

[0007] Application No.: CN202411456113.2. Inventors: Du Jianmin, Du Zonglin, Du Wenjie. "Silicone-free carbon fiber spinning finish and its preparation method" are disclosed. The spinning finish includes the following components: 40 - 55 parts of ester lubricant, 10 - 15 parts of surfactant, 10 - 20 parts of composite antistatic agent, 4 - 8 parts of glycerol, 5 - 8 parts of bundling agent, 0.2 - 2 parts of antioxidant, 0.1 - 1 part of defoamer, 0.5 - 2 parts of antiseptic and fungicide, 0 - 6 parts of emulsifier, 100 - 150 parts of water; for such oil agents prepared by mechanical emulsification, the dosage of emulsifier is too high, it is not easy to form a film, the film formation is uneven, the heat resistance is not high, it is easy to demulsify and stratify after being stored for too long, and too much and too fast loss of the oil agent occurs during the pre-oxidation stage, making the pre-oxidation unstable and prone to yellowing, resulting in carbon fiber defects.

[0008] U.S. Patent US20170284016A1. The oil agent mainly includes the compounding of epoxy modified silicone oil, amine modified silicone oil, polyether modified silicone oil and other auxiliary additives. The function of the oil agent is to protect the polyacrylonitrile carbon fiber precursor filaments from sticking to the rollers, melting and filament bunching during pre-oxidation in an air atmosphere at 200 - 400°C and carbonization in an inert gas atmosphere, and during the process when the temperature reaches 1000°C or above.

[0009] Based on the above analysis, there are generally problems such as poor fastness, heat resistance, antistatic property, softness and easy yellowing in the current domestic oil agents for carbon fiber precursor filaments, resulting in problems such as sticking, filament bunching, fluffing, winding, breaking and oxidation yellowing of the precursor filaments during high-temperature steam stretching, pre-oxidation, carbonization and other processing processes, and it is difficult to meet the requirements for preparing high-performance polyacrylonitrile carbon fibers. Summary of the Invention

[0010] In view of the deficiencies of the existing technologies such as poor fastness, antistatic property, heat resistance, antioxidant property, softness and easy yellowing in the oil agent for polyacrylonitrile carbon fiber precursor filaments, the present invention provides a high-performance oil agent for polyacrylonitrile carbon fiber precursor filaments and its preparation method.

[0011] To achieve the above object, the present invention adopts the following technical solutions: A high-performance sizing agent for polyacrylonitrile carbon fiber precursor and a preparation method thereof, wherein the sizing agent is composed of the following raw materials in mass percentages: Phenyl silicone oil 5-40%, polyether / aminopolysiloxane block copolymer 5-60%, quaternary ammonium salt-based polysiloxane 3-35%, antioxidant 0.01-0.50%, emulsifier 1-10%, deionized water 5-80%.

[0012] Among them, the phenyl silicone oil is a polysiloxane substituted by phenyl groups. Such silicone oils have unique physical and chemical properties, such as low freezing point, high thermal stability, good radiation resistance, oxidation stability, heat resistance, flame resistance, ultraviolet resistance and chemical resistance characteristics, and have good dispersibility and stability in the water-based system.

[0013] Preferably, the phenyl silicone oil is one or a mixture of more than one of methylphenyl silicone oil, phenylvinyl silicone oil, phenylhydrogen silicone oil, and hydroxy-terminated phenyl silicone oil in any proportion.

[0014] Preferably, the phenyl silicone oil is selected from one of methylphenyl silicone oil and hydroxy-terminated phenyl silicone oil, or a mixture of the two in a ratio of 1:1.

[0015] Among them, the polyether / aminopolysiloxane block copolymer is a block polymer formed by copolymerization of polyether and aminopolysiloxane, and is obtained by block copolymerization reaction of polyether I and aminopolysiloxane II to obtain III.

[0016] Among them, specifically, in the aminopolysiloxane II, R1 is a hydroxyl group (-OH), the alkyl group a is an integer of 10-20, and the average degree of polymerization n of the polysiloxane is between 12-25; in the polyether I, the average degree of polymerization m of the polyether is between 6-13;

[0017] The polyether / aminopolysiloxane block copolymer has a viscosity between 2,000 mPa·S and 7,500 mPa·S (25°C) and an amine value between 0.1 and 0.5.

[0018] The quaternary ammonium salt-based polysiloxane is one or any mixture of any two in any proportion of hydroxyl-containing active polysiloxane quaternary ammonium salt, quaternary ammonium salt type organosilicon gemini surfactant, polysiloxane quaternary ammonium salt-17, active polysiloxane quaternary ammonium salt, and Gemini type surfactant.

[0019] Preferably, the quaternary ammonium salt-based polysiloxane is specifically one or a mixture of two kinds in any proportion of quaternary ammonium salt-type organosilicon gemini surfactant and reactive polysiloxane quaternary ammonium salt, with a specific viscosity between 1500 and 2000 mPa·s and the amine value controlled between 0.2 and 0.6.

[0020] The antioxidant can effectively prevent the oxidation and deterioration of the sizing agent for polyacrylonitrile carbon fiber precursor during storage, and is one or a mixture of two kinds in any proportion of BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole).

[0021] The emulsifier is one or a mixture of any two of emulsifier EL-12, EL-40, Peregal A-20, octadecyl phosphate, and AE09. Preferably, it is a mixture of emulsifier EL-12 and octadecyl phosphate in a mass ratio of 1:1.

[0022] Among them, the deionized water is ultrapure water, and the required resistivity is ≥18.2 MΩ·cm (25°C).

[0023] A high-performance sizing agent for polyacrylonitrile carbon fiber precursor and its preparation method are composed of raw materials in the following mass percentages: phenyl silicone oil 5-40%, polyether / amino polysiloxane block copolymer 5-60%, quaternary ammonium salt-based polysiloxane 3-35%, antioxidant 0.01-0.50%, emulsifier 1-10%, and deionized water 5-80%.

[0024] A high-performance sizing agent for polyacrylonitrile carbon fiber precursor and its preparation method include the following processing steps: In a jacketed stainless steel homogenizing reactor, first add deionized water, heat the jacket with steam to 70-95°C, and sequentially metering and adding the emulsifier, polyether / amino polysiloxane block copolymer, quaternary ammonium salt-based polysiloxane, and antioxidant while stirring. Keep stirring at a constant temperature for 30 minutes. After all are dissolved, add phenyl silicone oil, stop after homogenizing with a homogenizer for 15 minutes, continue stirring at a constant temperature for 10-30 minutes, and then cool down. When the temperature drops to 30-45°C, the reaction ends, and it is the finished product.

[0025] The present invention has the following beneficial effects

[0026] The present invention provides a brand-new structure, which is easy to firmly combine with polyacrylonitrile fiber, has good softness and antistatic properties, improves the hand feeling of the fiber, and further enhances the anti-yellowing property.

[0027] The present invention can improve the heat resistance of polyacrylonitrile fiber, significantly reduce the generation of oil scale in the drying process and eliminate the phenomenon of sticking rollers, effectively prevent the occurrence of hairiness, breakage, doubling, adhesion, etc. of the precursor during pre-oxidation, and at the same time has good anti-irradiation performance, and its oxidation stability, anti-ultraviolet property and chemical resistance are all better.

[0028] The present invention has extremely strong hydrophilicity and self-emulsifying ability, with a small amount of emulsifier used and being environmentally friendly. Detailed implementation mode

[0029] The present invention will be further described below in conjunction with embodiments.

[0030] Example 1

[0031] A high-performance polyacrylonitrile carbon fiber precursor sizing agent and its preparation method are composed of raw materials in the following mass percentages: Methylphenyl silicone oil 17%, polyether / aminopolysiloxane block copolymer 12%, quaternary ammonium salt type organosilicon gemini surfactant 6%, butylated hydroxytoluene 0.15%, a 1:1 mixture of emulsifier EL-12 and octadecyl phosphate 2.5%, deionized water 62.4%.

[0032] A high-performance polyacrylonitrile carbon fiber precursor sizing agent and its preparation method include the following processing steps: In a sandwich stainless steel homogenizing reactor, first add 62.4 Kg of deionized water, start stirring, control the stirring speed at 100 rpm / min, heat the reactor sandwich with steam to 85 °C, sequentially measure and add 2.5 Kg of a 1:1 mass ratio mixture of EL-12 and octadecyl phosphate, 12 Kg of polyether / aminopolysiloxane block copolymer, 6 Kg of quaternary ammonium salt type organosilicon gemini surfactant. After all are dissolved, then add 17 Kg of methylphenyl silicone oil and 0.15 Kg of butylated hydroxytoluene, stir until dissolved, turn on the homogenizer, homogenize for 15 minutes, continue to keep warm at 85 °C, stir for 15 - 30 minutes and then cool down, and discharge at 30 - 40 °C.

[0033] Example 2

[0034] A high-performance polyacrylonitrile carbon fiber precursor sizing agent and its preparation method are composed of raw materials in the following mass percentages: Hydroxyl-terminated phenyl silicone oil 15%, polyether / aminopolysiloxane block copolymer 13%, active polysiloxane quaternary ammonium salt 4.5%, butylated hydroxyanisole 0.1%, a 1:1 mixture of emulsifier EL-12 and octadecyl phosphate 2.0%, deionized water 65.4%.

[0035] A high-performance sizing agent for polyacrylonitrile carbon fiber precursor and its preparation method, including the following processing steps: In a sandwich stainless steel average reaction kettle, first add 65.4 Kg of deionized water, start stirring, control the stirring speed at 100 rpm / min, pass steam through the sandwich, heat up to 90 °C, and sequentially measure and add 2.0 Kg of a mixture of EL-12 and octadecyl phosphate in a mass ratio of 1:1, 13 Kg of polyether / aminopolysiloxane block copolymer, and 4.5 Kg of active polysiloxane quaternary ammonium salt. After all are dissolved, then add 15 Kg of hydroxyl-terminated phenyl silicone oil and 0.1 Kg of butylhydroxyanisole, stir until dissolved, stop after an average of 15 minutes, stir at 90 °C for 15 - 30 minutes and then cool down, and discharge at 35 - 40 °C.

[0036] Comparative Example 1 The said Comparative Example 1 is a sizing agent for polyacrylonitrile carbon fiber precursor produced by Takemoto Oil & Fat Co., Ltd. of Japan.

[0037] Comparative Example 2 The said Comparative Example 2 is a sizing agent for polyacrylonitrile carbon fiber precursor produced by Sima Co., Ltd. of Germany.

[0038] Use Example 1, Example 2 of the present invention and Comparative Example 1, Comparative Example 2 to size the same polyacrylonitrile carbon fiber precursor respectively, and the heat residue and ash content in the air environment are shown in Table 1 It can be seen from Table 1 that the oil content rate of the precursor after sizing in Comparative Example 1 is basically close to that in Example 1 and Example 2, the residual percentage mass after low and high temperature pre-oxidation is similar, the drawing strength is lower than that in Example 1 and Example 2, and the ash content is slightly higher than that in Example 1 and Example 2; the oil content rate of the precursor and pre-oxidized fiber in Comparative Example 2 is the highest, the heat resistance is the highest, but it is not easy to remove after low and high temperature carbonization, the residual ash content of the carbon fiber is high, and the strength of the carbon fiber is reduced; The high-performance sizing agent for polyacrylonitrile carbon fiber precursor of the present invention has performance similar to that of the sizing agent for polyacrylonitrile carbon fiber precursor produced by Takemoto Oil & Fat Co., Ltd. of Japan, and has significantly improved the heat resistance of the precursor. Under the pre-oxidation condition of 300 °C, more than 90% of the sizing agent residue can still be maintained, and the protection of the polyacrylonitrile carbon fiber precursor is obvious.

[0039] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent structural or equivalent process transformations made by using the content of the specification of the present invention, or directly or indirectly applied in other related technical fields, are equally included in the patent protection scope of the present invention.

Claims

1. A high-performance sizing agent for polyacrylonitrile carbon fiber precursor and its preparation method, characterized in that: It consists of raw materials in the following mass percentages: Phenyl silicone oil 5 - 40%, polyether / aminopolysiloxane block copolymer 5 - 60%, quaternary ammonium salt-based polysiloxane 3 - 35%, antioxidant 0.01 - 0.50%, emulsifier 1 - 10%, deionized water 5 - 80%; It includes the following processing steps: In a jacketed stainless steel homogenizing reactor, first add deionized water, heat the jacket with steam to 70 - 95°C, sequentially metering and adding the emulsifier, polyether / aminopolysiloxane block copolymer, quaternary ammonium salt-based polysiloxane, and antioxidant while stirring, stir at a constant temperature for 30 minutes, then add phenyl silicone oil after all are dissolved, stop after homogenizing with a homogenizer for 15 minutes, continue stirring at a constant temperature for 10 - 30 minutes and then cool down, stop cooling when the temperature reaches 30 - 45°C to obtain the finished product.

2. A high-performance polyacrylonitrile carbon fiber precursor sizing agent and its preparation method according to claim 1, characterized in that: The phenyl silicone oil is one or a mixture of more than one of methylphenyl silicone oil, phenylvinyl silicone oil, phenylhydrogen silicone oil, and hydroxyl-terminated phenyl silicone oil mixed in any proportion.

3. A high-performance polyacrylonitrile carbon fiber precursor sizing agent and its preparation method according to claim 1, characterized in that: The polyether / aminopolysiloxane block copolymer, this block copolymer contains a block polymer formed by copolymerization of polyether and aminopolysiloxane, and is obtained by block copolymerization reaction of polyether I and aminopolysiloxane II to get III. Among them, the average polymerization degree m of the polyether in the polyether I is between 6 and 13, R1 in the aminopolysiloxane II is a hydroxyl group (-OH), the alkyl a is an integer of 10 - 20, and the average polymerization degree n of the siloxane is between 12 and 25.

4. A high-performance polyacrylonitrile carbon fiber precursor sizing agent according to claim 1 and its preparation method, characterized in that: The polyether / aminopolysiloxane block copolymer, with a viscosity between 2,000 mPa·S and 7,500 mPa·S (25°C) and an amine value between 0.1 and 0.

5.

5. A high-performance polyacrylonitrile carbon fiber precursor sizing agent according to claim 1 and its preparation method, characterized in that: The quaternary ammonium salt-based polysiloxane is one or a mixture of two of quaternary ammonium salt-type organosilicon gemini surfactant and reactive polysiloxane quaternary ammonium salt (PQMS) in any proportion, with a specific viscosity between 1,500 - 2,000 mPa·s and the amine value controlled between 0.2 and 0.

6.

6. A high-performance polyacrylonitrile carbon fiber precursor sizing agent and its preparation method according to claim 1, characterized in that: The emulsifier is a mixture of EL-12 and octadecyl phosphate ester in a mass ratio of 1:1.

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