Highly hydrophobic polyacrylonitrile spinning dope and method for preparing the same

Abstract

The application discloses a high-hydrophobic polyacrylonitrile spinning solution and a preparation method thereof. The high-hydrophobic polyacrylonitrile spinning solution is prepared by copolymerization of acrylonitrile, fluorine-containing monomers and alkenyl silane in an organic solution. The fluorine-containing monomers have the structure shown in formula A. The high-hydrophobic polyacrylonitrile spinning solution provided by the application can significantly improve the chemical stability and wear resistance of the fiber material prepared from the polyacrylonitrile spinning solution based on the copolymerized fluorine-containing monomers and alkenyl silane. The tertiary amine, fluorocarbon and silane structures in the monomers can effectively change the hydrophobic capacity of the fiber material, so that the fiber material has excellent hydrophobic capacity and can be widely applied to polyacrylonitrile fiber materials in the field of oil-water separation.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a highly hydrophobic polyacrylonitrile spinning solution and its preparation method. Background Technology

[0002] The advent of high-performance carbon fiber marks another breakthrough in the history of materials development. It possesses excellent properties such as high specific strength, high specific modulus, ablation resistance, wear resistance, and fatigue resistance. As the most important reinforcing material in the field of advanced composite materials, it is widely used in various fields, including military and civilian industries. Compared with viscose-based and pitch-based carbon fibers, polyacrylonitrile-based carbon fiber has seen significant development due to its simpler production process and better mechanical properties, becoming the main direction of carbon fiber development.

[0003] Polyacrylonitrile-based carbon fiber is a new material that developed rapidly in the 1960s. Due to its excellent properties such as light weight, high specific strength, high specific modulus, high temperature resistance, corrosion resistance, wear resistance, fatigue resistance, electrical conductivity, and thermal conductivity, it is widely used in military industries such as satellites, launch vehicles, tactical missiles, and spacecraft, and has become an indispensable material in the aerospace industry. High-quality carbon fiber precursors should possess characteristics such as high heat resistance, few pore structures, few surface defects, dense structure, and good tensile strength.

[0004] Polyacrylonitrile-based carbon fiber is prepared by spinning a polymer with acrylonitrile as the main chain structural unit, followed by oxidation and carbonization. The synthesis of acrylonitrile copolymer is the first step in the preparation of precursor fiber. The quality of polyacrylonitrile precursor fiber is affected not only by the spinning process conditions, but more importantly by the microstructure of the polymer molecular chain, such as the type, composition, molecular weight, and molecular weight distribution of the comonomer. Therefore, high-quality polyacrylonitrile polymer is a prerequisite for the preparation of high-quality precursor fiber.

[0005] Spinning solutions used to prepare polyacrylonitrile precursor fibers are classified into homopolymers and copolymers. Homopolymers of acrylonitrile have poor solubility, resulting in poor spinnability. Furthermore, due to the presence of numerous -CN groups in their chemical structure, strong intermolecular forces, and the lack of side chains, the pre-oxidation and carbonization processes are lengthy, leading to high product cost and low strength. To overcome these shortcomings of homopolymer polyacrylonitrile resins, the resin is typically modified by adding binary or multi-vinyl comonomers to the acrylonitrile.

[0006] However, the stability of fiber materials produced by polyacrylonitrile spinning dope in existing technologies still needs to be improved, and they do not have high hydrophobicity, which limits their application in the field of oil-water separation.

[0007] Therefore, there is an urgent need for a polyacrylonitrile spinning solution that can significantly improve the stability and hydrophobicity of fiber materials. Summary of the Invention

[0008] Purpose of the invention: In view of the deficiencies of the prior art, the purpose of this invention is to provide a highly hydrophobic polyacrylonitrile spinning solution that can significantly improve the stability and hydrophobicity of fiber materials and its preparation method.

[0009] Technical solution:

[0010] A highly hydrophobic polyacrylonitrile spinning solution is prepared by copolymerization of acrylonitrile, fluorinated monomers and alkenyl silanes in an organic solution.

[0011] The fluorinated monomer has the structure shown in formula A:

[0012] .

[0013] The highly hydrophobic polyacrylonitrile spinning solution of the present invention has a polyacrylonitrile structure with good processability. After spinning, it can form a fiber material with good mechanical properties and weather resistance. It can not only replace wool as a textile, but also be made into a fiber membrane as a membrane material for oil-water separation.

[0014] Further, the fluorinated monomer is prepared by the following steps: 1H,1H-perfluoro-1-hexanol and 3-N,N-dimethylaminomethacryloyl chloride are added to a reactor, and the reaction is carried out under the protection of a polymerization inhibitor. After heating, the reaction is completed, cooled, washed, dried, and distilled to obtain the fluorinated monomer.

[0015] The highly hydrophobic polyacrylonitrile spinning solution of the present invention has a tertiary amine structure and a long-chain fluorocarbon structure in its copolymerized fluorinated monomer. On the one hand, the non-polar and multi-branched tertiary amine structure can endow polyacrylonitrile with excellent hydrophobicity and improve the dispersibility of the resulting fibers, thereby increasing the number of pores on the fiber surface. On the other hand, the long-chain fluorocarbon structure can not only further improve the hydrophobicity of polyacrylonitrile, but also significantly improve the chemical resistance of the material.

[0016] Furthermore, the mass ratio of 1H,1H-perfluoro-1-hexanol to 3-N,N-dimethylaminomethacryloyl chloride is 2-2.5:1.

[0017] Furthermore, the polymerization inhibitor is selected from hydroquinone, p-methoxyphenol, or 2,6-di-tert-butyl-p-cresol.

[0018] Furthermore, the reaction temperature is 40-70℃, and the reaction time is 8-16 hours.

[0019] Furthermore, the alkenylsilane is selected from allyltriethoxysilane, vinyltriacetylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, or γ-methacrylatepropyltrimethoxysilane.

[0020] The highly hydrophobic polyacrylonitrile spinning solution of the present invention has a copolymerized alkenylsilane monomer with a multi-branched silane structure. On the one hand, its multi-branched spatial structure can further improve the hydrophobicity of polyacrylonitrile; on the other hand, its silane structure can be uniformly dispersed on the surface of the fiber and cross-linked to form a stable network structure. This not only improves the chemical stability of the fiber material, but also plays a protective role during the friction process of the fiber material, improving its wear resistance and further extending its service life.

[0021] Furthermore, the organic solvent is selected from N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide.

[0022] The preparation method of any of the above-mentioned highly hydrophobic polyacrylonitrile spinning dopes includes the following steps: adding acrylonitrile, fluorinated monomer, alkenyl silane, initiator and organic solvent to a reactor, heating to 50-70℃ and reacting for 12-40 hours, and removing residual monomers and bubbles under reduced pressure to obtain the highly hydrophobic polyacrylonitrile spinning dopes.

[0023] Furthermore, the initiator is selected from one of azobisisobutyronitrile or azobisisoheptanenitrile.

[0024] Furthermore, the molar ratio of acrylonitrile, fluorinated monomer and alkenylsilane is (25-30):(5-8):(3-5).

[0025] Beneficial effects:

[0026] (1) The high hydrophobic polyacrylonitrile spinning solution provided by the present invention is obtained by copolymerization of acrylonitrile, fluorinated monomer and alkenyl silane in an organic solution. Based on the copolymerization of fluorinated monomer and alkenyl silane, the chemical stability and wear resistance of the fiber material obtained by polyacrylonitrile spinning solution can be significantly improved. Furthermore, the tertiary amine, carbon fluorine and silane structure in its monomer can effectively change the hydrophobicity of the fiber material, giving it excellent hydrophobicity. It can be widely used in polyacrylonitrile fiber materials in the field of oil-water separation.

[0027] (2) The highly hydrophobic polyacrylonitrile spinning solution provided by the present invention has good processability due to its polyacrylonitrile structure. After spinning, it can form a fiber material with good mechanical properties and weather resistance. It can not only replace wool as a textile, but also be made into a fiber membrane as a membrane material for oil-water separation.

[0028] (3) In the high hydrophobic polyacrylonitrile spinning solution provided by the present invention, the copolymerized fluorine-containing monomers have tertiary amine structure and long-chain fluorocarbon structure. On the one hand, the non-polar and multi-branched tertiary amine structure can endow polyacrylonitrile with excellent hydrophobicity and improve the dispersibility of the fiber, thereby increasing the number of pores on the fiber surface. On the other hand, the long-chain fluorocarbon structure can not only further improve the hydrophobicity of polyacrylonitrile, but also significantly improve the chemical resistance of the material.

[0029] (4) In the high hydrophobic polyacrylonitrile spinning solution provided by the present invention, the copolymerized alkenyl silane monomer has a multi-branched silane structure. On the one hand, its multi-branched spatial structure can further improve the hydrophobicity of polyacrylonitrile; on the other hand, its silane structure can be uniformly dispersed on the surface of the fiber and cross-linked to form a stable network structure, which can not only improve the chemical stability of the fiber material, but also play a protective role in the friction process of the fiber material, improve its wear resistance, and further improve its service life.

[0030] (5) The high hydrophobic polyacrylonitrile spinning solution provided by the present invention, by simultaneously grafting fluorine-containing monomers and alkenyl silane structures into polyacrylonitrile, allows the long-chain carbon-fluorine structure and silane structure to be uniformly distributed on the surface of the fiber material at the same time, which can compensate for the defects in the spatial structure between them, improve the density of the surface structure of the fiber material, and significantly improve the stability of the fiber material through the synergistic effect. Detailed Implementation

[0031] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0032] The commercially available polyacrylonitrile spinning solution was prepared by mixing fine PAN powder purchased from Dongguan Zhangmutou Hengtai Plastic Raw Materials Business Department with N,N-dimethylformamide; the other reagents and equipment were conventional reagents and equipment in this technical field.

[0033] Preparation of fluorine-containing monomers

[0034] Fluorine-containing monomers are prepared by the following steps:

[0035] In a reactor, 2g of 1H,1H-perfluoro-1-hexanol and 1g of 3-N,N-dimethylaminomethacryloyl chloride were added. Under the protection of 0.1g hydroquinone, the mixture was heated to 60°C and reacted for 12 hours. After cooling, washing, drying, and distillation, the fluorinated monomer was obtained.

[0036] Mass spectrometry data of fluorine-containing monomers: The products were analyzed by LC-MS, and the m / z of the products were 411.07 (100.0%) and 412.10 (13.9%).

[0037] Example 1

[0038] The highly hydrophobic polyacrylonitrile spinning solution was prepared by the following steps:

[0039] In a closed reactor, 0.3 mol of acrylonitrile, 0.05 mol of fluorinated monomer, 0.03 mol of allyltriethoxysilane, 0.3 g of azobisisobutyronitrile and 100 mL of N,N-dimethylformamide were added. The mixture was heated to 70 °C and reacted for 24 hours. After removing residual monomers and bubbles under reduced pressure, the highly hydrophobic polyacrylonitrile spinning solution was obtained.

[0040] Example 2

[0041] The method is basically the same as in Example 1, except that each monomer and its content are changed to 0.25 mol of acrylonitrile, 0.08 mol of fluorinated monomer and 0.04 mol of vinyltriacetylsilane.

[0042] Example 3

[0043] The method is basically the same as in Example 1, except that the monomers and their contents are changed to 0.23 mol of acrylonitrile, 0.08 mol of fluorinated monomer and 0.05 mol of γ-methacrylate propyltrimethoxysilane.

[0044] Comparative Example 1

[0045] Commercially available polyacrylonitrile spinning dope.

[0046] Comparative Example 2

[0047] The process is basically the same as in Example 1, except that the fluorinated monomer is replaced with an equal amount of acrylonitrile.

[0048] Comparative Example 3

[0049] The basic formula is the same as in Example 1, except that allyltriethoxysilane is replaced with an equal amount of vinylidene chloride.

[0050] Comparative Example 4

[0051] The method is basically the same as in Example 1, except that the fluorinated monomer is replaced with an equal amount of acrylonitrile and the allyltriethoxysilane is replaced with an equal amount of vinylidene chloride.

[0052] Performance testing

[0053] The products of Examples 1-3 and Comparative Examples 1-4 were prepared into fibers of the same specifications through wet spinning, coagulation molding, washing, hot stretching, drying, and heat setting, respectively, and then their performance was tested.

[0054] Tensile strength test: The tensile strength of the fibers obtained from Examples 1-3 and Comparative Examples 1-4 was tested according to the test standard of GB / T 3362-2005 Tensile Properties Test Method for Carbon Fiber Multifilament.

[0055] Acid resistance test: The fibers obtained from the products of Examples 1-3 and Comparative Examples 1-4 were immersed in a 25wt% sulfuric acid aqueous solution for 240 hours, and the tensile strength of the fibers after immersion was tested again.

[0056] Alkali resistance test: The fibers obtained from the products of Examples 1-3 and Comparative Examples 1-4 were immersed in a 10wt% sodium hydroxide aqueous solution for 240 hours, and the tensile strength of the fibers after immersion was tested again.

[0057] Abrasion resistance test: According to the test method of GB / T1768-2006, the abrasion quality of the fibers obtained from the products of Examples 1-3 and Comparative Examples 1-4 above was tested under the condition of 750g / 500r.

[0058] Hydrophobicity test: The water contact angle of the fibers made from the products of Examples 1-3 and Comparative Examples 1-4 was tested.

[0059] The test results are shown in the table below:

[0060]

[0061] According to the comparison of the test results of Examples 1-3 and Comparative Example 1, the fiber material prepared by the highly hydrophobic polyacrylonitrile spinning solution provided by the present invention has excellent mechanical strength and stability, and strong hydrophobicity, and can be effectively applied in the field of oil-water separation.

[0062] According to the comparison of the test results of Examples 1-3 and Comparative Examples 2-4, the highly hydrophobic polyacrylonitrile spinning solution provided by the present invention can significantly improve the mechanical strength, acid and alkali resistance and wear resistance of the fiber material through the structure of its polymerized fluorinated monomers and alkenyl silane monomers, and can also significantly improve the hydrophobic properties of the fiber material.

[0063] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A highly hydrophobic polyacrylonitrile spinning solution, characterized in that, The highly hydrophobic polyacrylonitrile spinning solution is prepared by copolymerization of acrylonitrile, fluorinated monomers and alkenyl silanes in an organic solvent. The fluorinated monomer has the structure shown in formula A: ； The alkenylsilane is selected from one of allyltriethoxysilane, vinyltriacetylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, or γ-methacrylatepropyltrimethoxysilane; The molar ratio of acrylonitrile, fluorinated monomer and alkenylsilane is (25-30):(5-8):(3-5).

2. The highly hydrophobic polyacrylonitrile spinning solution according to claim 1, characterized in that, The fluorinated monomer is prepared by the following steps: 1H,1H-perfluoro-1-hexanol and 3-N,N-dimethylaminomethacryloyl chloride are added to a reactor, and the reaction is carried out under the protection of a polymerization inhibitor. After heating, the reaction is completed, cooled, washed, dried, and distilled to obtain the fluorinated monomer.

3. The highly hydrophobic polyacrylonitrile spinning solution according to claim 2, characterized in that, The mass ratio of 1H,1H-perfluoro-1-hexanol to 3-N,N-dimethylaminomethacryloyl chloride is 2-2.5:

1.

4. The highly hydrophobic polyacrylonitrile spinning solution according to claim 2, characterized in that, The polymerization inhibitor is selected from hydroquinone, p-methoxyphenol, or 2,6-di-tert-butyl-p-cresol.

5. The highly hydrophobic polyacrylonitrile spinning solution according to claim 2, characterized in that, The reaction temperature is 40-70℃, and the reaction time is 8-16 hours.

6. The highly hydrophobic polyacrylonitrile spinning solution according to claim 1, characterized in that, The organic solvent is selected from one of N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide.

7. The method for preparing the highly hydrophobic polyacrylonitrile spinning solution according to any one of claims 1-6, characterized in that, The process includes the following steps: adding acrylonitrile, fluorinated monomer, alkenylsilane, initiator and organic solvent to a reactor, heating to 50-70℃ and reacting for 12-40 hours, and then removing residual monomer and bubbles under reduced pressure to obtain the highly hydrophobic polyacrylonitrile spinning dope.

8. The method for preparing the highly hydrophobic polyacrylonitrile spinning solution according to claim 7, characterized in that, The initiator is selected from either azobisisobutyronitrile or azobisisoheptanenitrile.

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