A kind of hollow polyimide fiber and preparation method thereof
The preparation of hollow polyimide fibers through dry spinning process solves the problem of slow development of polyimide fibers in the civil field, and achieves the effect of low cost, easy processing and good thermal insulation performance.
Patent Information
- Application Number
- CN202411846449.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-16
- Publication Date
- 2025-04-04
AI Technical Summary
The existing polyimide fibers are relatively slow to develop in the civil field, mainly due to high costs, difficult processing, limited color and insufficient insulation performance.
The dry spinning process is adopted to form a hollow structure of polyimide fibers with a hollow structure by mixing the spinning liquid of thermoplastic polyimide, polyamic acid and solvent.
It achieves low cost, easy processing, easy dyeing, comfortable feel and good insulation performance, and is suitable for the civil market.
Smart Images
Figure CN119753889A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of fiber preparation, and in particular to a hollow polyimide fiber and a preparation method thereof. Background Art
[0002] Polyimide fiber is limited by cost, color, processing and other factors, and its development in civilian applications is relatively slow. In view of this situation, the development of low-cost, easy-to-process, easy-to-dye, comfortable-to-touch, and heat-insulating polyimide is of great significance to the civilian market.
[0003] Conventional hollow fiber production methods can be classified into "core replacement method" and "special-shaped spinneret method". The core replacement method has complicated operation steps and low efficiency. The special-shaped spinneret method has low hollowness and poor spinning operation performance. Summary of the invention
[0004] The purpose of the present invention is to provide a hollow polyimide fiber and a preparation method thereof in view of the above-mentioned deficiencies in the prior art.
[0005] The invention discloses a method for preparing hollow polyimide fibers. The hollow polyimide fibers are prepared by dry spinning a mixed spinning solution consisting of thermoplastic polyimide, polyamic acid and a solvent.
[0006] Furthermore, the temperature of the dry spinning tunnel is higher than the melting point of the thermoplastic polyimide and the boiling point of the solvent, and the absolute value of the difference between the boiling point of the solvent and the melting point of the thermoplastic polyimide does not exceed 20 degrees Celsius.
[0007] Furthermore, the solvent is selected from a mixture of one or more of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.
[0008] Furthermore, the synthesis method of the thermoplastic polyimide is a melt polymerization method or a solution polymerization chemical cyclization method.
[0009] Further, the raw material for synthesizing thermoplastic polyimide, the diamine is selected from one or more of p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, and the dianhydride is selected from one or more of pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride;
[0010] The raw materials for synthesizing polyamic acid are: the diamine is selected from one or more of p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenylmethane; and the dianhydride is selected from one or more of pyromellitic dianhydride and biphenyltetracarboxylic dianhydride.
[0011] Further, the specific steps include:
[0012] S1: Synthesize thermoplastic polyimide by one-step process to make powder or small crystalline particles;
[0013] S2: dissolving thermoplastic polyimide powder or granules into a thermoplastic polyimide solution using a solvent;
[0014] S3: synthesizing a polyamic acid solution by solution polymerization;
[0015] S4: adding the thermoplastic polyimide solution to the polyamic acid solution, mixing them evenly, and degassing to obtain a mixed spinning solution;
[0016] S5: by controlling the spinning process parameters of the spinneret temperature, the tunnel temperature and the air volume, the mixed spinning solution is subjected to dry spinning to obtain the polyimide primary yarn with a hollow structure;
[0017] S6: The spun silk is cyclized and drawn at high temperature to obtain hollow polyimide fibers.
[0018] Furthermore, in the above step S2, the concentration of the thermoplastic polyimide solution is 20%-50%.
[0019] Furthermore, in the above step S3, the concentration of the polyamic acid solution is 15%-30%.
[0020] Furthermore, in the above step S5, the temperature of the spinning tunnel is between 150°C and 250°C; and the temperature of the spinneret is between 0°C and 50°C.
[0021] A hollow polyimide fiber prepared by the above preparation method.
[0022] In the dry spinning process of the present invention, the mixed spinning solution is heated by hot air in the tunnel after passing through the spinneret. When the mixed spinning solution reaches or approaches the boiling point of the solvent, it also reaches or approaches the melting point of the thermoplastic polyimide. During the volatilization of the solvent, the thermoplastic polyimide in the mixed spinning solution gradually turns into a thermoplastic polyimide melt. As the solvent in the polyamic acid decreases and gradually forms into fibers, a small amount of vaporized and expanded solvent in the center of the fiber is wrapped by the thermoplastic polyimide melt. Under the involvement of the fiber winding machine, a hollow tube is formed inside the polyimide fiber.
[0023] The present invention can obtain thermoplastic polyimide with different melting points by controlling the ratio of thermoplastic polyimide raw materials, and can control the hollowness of polyimide fiber by controlling the ratio of thermoplastic polyimide, polyamic acid and solvent.
[0024] The hollow polyimide fiber produced in this way has the characteristics of high temperature resistance and plasticity, which is convenient for subsequent processing into a variety of products. The hollow polyimide fiber produced in this way has excellent properties such as heat resistance, warmth retention, antibacterial, radiation resistance, and easy dyeing. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 and Figure 2 Physical diagram of the process adjustment stage;
[0026] Figure 3-7 This is a scanning electron microscope image of the cross section of the hollow polyimide fiber prepared in Example 1-5. DETAILED DESCRIPTION
[0027] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.
[0028] Example 1
[0029] A method for preparing a hollow polyimide fiber comprises the following steps:
[0030] (1) 4,4'-diaminodiphenylmethane is selected from the raw material diamine, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride and pyromellitic dianhydride are selected from the dianhydride, and the molar ratio of the two dianhydride components is 9:1. The thermoplastic polyimide is synthesized by melt polymerization to prepare a powder. The synthesized thermoplastic polyimide is tested and its melting point is 160°C-166°C.
[0031] (2) Thermoplastic polyimide powder is dissolved in N,N-dimethylacetamide, a solvent, to obtain a thermoplastic polyimide solution having a concentration of 35%.
[0032] (3) 4,4'-diaminodiphenyl ether is selected from the raw material diamine, pyromellitic anhydride and biphenyltetracarboxylic anhydride are selected from the dianhydride, the molar ratio of the two dianhydrides is 9:1, and N,N-dimethylacetamide is selected as the solvent to synthesize a polyamic acid solution with a concentration of 20% by solution polymerization.
[0033] (4) Add the above thermoplastic polyimide solution to the polyamic acid solution in a mass ratio of 1:2, mix evenly, and degas to obtain a mixed spinning solution.
[0034] (5) by controlling the spinning process parameters such as spinneret temperature of 10°C, tunnel temperature of 185°C and air volume, the mixed spinning solution is subjected to dry spinning to obtain polyimide primary yarn with a hollow structure;
[0035] (6) The spun silk is cyclized and drawn at high temperature to obtain hollow polyimide fibers.
[0036] Key process parameters in steps (1, 2, 3, 4, 5)
[0037]
[0038] Example 2
[0039] A method for preparing a hollow polyimide fiber comprises the following steps:
[0040] (1) 4,4'-diaminodiphenyl ether is selected from the raw material diamine, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride and pyromellitic dianhydride are selected from the dianhydride, and the molar ratio of the two dianhydride components is 8:2. The thermoplastic polyimide is synthesized by melt polymerization to prepare small crystal particles. The synthesized thermoplastic polyimide has a melting point of 178°C-182°C through testing.
[0041] (2) Thermoplastic polyimide particles were dissolved in N-methylpyrrolidone solvent to form a thermoplastic polyimide solution with a concentration of 38%.
[0042] (3) 4,4'-diaminodiphenyl ether is selected from the raw material diamine, pyromellitic anhydride and biphenyltetracarboxylic anhydride are selected from the dianhydride, the molar ratio of the two dianhydrides is 9:1, and N-methylpyrrolidone is selected as the solvent to synthesize a polyamic acid solution with a concentration of 22% by solution polymerization.
[0043] (4) Add the above thermoplastic polyimide solution to the polyamic acid solution in a mass ratio of 3:5, mix evenly, and degas to obtain a mixed spinning solution.
[0044] (5) by controlling the spinning process parameters such as spinneret temperature of 20° C., tunnel temperature of 220° C., and air volume, the mixed spinning solution is subjected to dry spinning to obtain polyimide primary yarn with a hollow structure;
[0045] (6) The spun silk is cyclized and drawn at high temperature to obtain hollow polyimide fibers.
[0046] Key process parameters in steps (1, 2, 3, 4, 5)
[0047]
[0048] Example 3
[0049] A method for preparing a hollow polyimide fiber comprises the following steps:
[0050] (1) 4,4'-diaminodiphenylmethane and 4,4'-diaminodiphenyl ether are selected from the raw material diamines, and the molar ratio of the two diamines is 5:5. 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is selected from the dianhydride, and thermoplastic polyimide is synthesized by melt polymerization to prepare small crystal particles. The synthesized thermoplastic polyimide has been tested and its melting point is 151°C-154°C.
[0051] (2) Thermoplastic polyimide particles are dissolved in N,N-dimethylformamide solvent to form a thermoplastic polyimide solution with a concentration of 32%.
[0052] (3) 4,4'-diaminodiphenylmethane is selected from the raw material diamines, pyromellitic acid dianhydride and biphenyltetracarboxylic acid dianhydride are selected from the dianhydrides, the molar ratio of the two dianhydrides is 9:1, and N,N-dimethylformamide is selected as the solvent to synthesize a polyamic acid solution with a concentration of 25% by solution polymerization.
[0053] (4) Add the above thermoplastic polyimide solution to the polyamic acid solution in a mass ratio of 1:2, mix evenly, and degas to obtain a mixed spinning solution.
[0054] (5) by controlling the spinning process parameters such as spinneret temperature of 5°C, tunnel temperature of 178°C and air volume, the mixed spinning solution is subjected to dry spinning to obtain polyimide primary yarn with a hollow structure;
[0055] (6) The spun silk is cyclized and drawn at high temperature to obtain hollow polyimide fibers.
[0056] Key process parameters in steps (1, 2, 3, 4, 5)
[0057]
[0058] Example 4
[0059] A method for preparing a hollow polyimide fiber comprises the following steps:
[0060] (1) 4,4'-diaminodiphenyl ether is selected from the raw material diamine, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride and pyromellitic dianhydride are selected from the dianhydride, and the two dianhydride components are synthesized by melt polymerization at a molar ratio of 7:3 to prepare a thermoplastic polyimide. The synthesized thermoplastic polyimide is tested and has a melting point of 195°C-201°C.
[0061] (2) Thermoplastic polyimide powder was dissolved in N-methylpyrrolidone solvent to obtain a thermoplastic polyimide solution with a concentration of 36%.
[0062] (3) Selecting 4,4'-diaminodiphenyl ether from the raw material diamine, selecting pyromellitic dianhydride from the dianhydride, and selecting N-methylpyrrolidone from the solvent, a polyamic acid solution with a concentration of 23% is synthesized by solution polymerization.
[0063] (4) Add the above thermoplastic polyimide solution to the polyamic acid solution in a mass ratio of 3:7, mix evenly, and degas to obtain a mixed spinning solution.
[0064] (5) by controlling the spinning process parameters such as spinneret temperature of 15° C., tunnel temperature of 230° C., and air volume, the mixed spinning solution is subjected to dry spinning to obtain polyimide primary filaments having a hollow structure;
[0065] (6) The spun silk is cyclized and drawn at high temperature to obtain hollow polyimide fibers.
[0066] Key process parameters in steps (1, 2, 3, 4, 5)
[0067]
[0068]
[0069] Example 5
[0070] A method for preparing a hollow polyimide fiber comprises the following steps:
[0071] (1) 4,4'-diaminodiphenyl ether is selected from the raw material diamine, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride and pyromellitic dianhydride are selected from the dianhydride, and the molar ratio of the two dianhydrides is 8:2. The thermoplastic polyimide is synthesized by melt polymerization to prepare a powder. The synthesized thermoplastic polyimide is tested and its melting point is 178°C-182°C.
[0072] (2) Solvent Selection: N,N-dimethylacetamide and N-methylpyrrolidone were mixed in a mass ratio of 5:5 to dissolve the thermoplastic polyimide powder into a thermoplastic polyimide solution with a concentration of 30%.
[0073] (3) 4,4'-diaminodiphenyl ether is selected from the raw material diamine, pyromellitic anhydride and biphenyltetracarboxylic anhydride are selected from the dianhydride, the molar ratio of the two dianhydrides is 9:1, and a mixture of N,N-dimethylacetamide and N-methylpyrrolidone in a mass ratio of 5:5 is selected as the solvent, and a polyamic acid solution with a concentration of 22% is synthesized by solution polymerization.
[0074] (4) Add the above thermoplastic polyimide solution to the polyamic acid solution in a mass ratio of 1:3, mix evenly, and degas to obtain a mixed spinning solution.
[0075] (5) by controlling the spinning process parameters such as spinneret temperature of 10° C., tunnel temperature of 200° C., and air volume, the mixed spinning solution is subjected to dry spinning to obtain polyimide primary yarn with a hollow structure;
[0076] (6) The spun silk is cyclized and drawn at high temperature to obtain hollow polyimide fibers.
[0077] Key process parameters in steps (1, 2, 3, 4, 5)
[0078]
[0079]
[0080] Figure 1 and Figure 2This is a physical picture of the process adjustment stage. You can see the process adjustment stage with the naked eye. The process and principle of hollow fiber formation. The vaporized solvent forms a hollow tube inside the fiber under controllable expansion, which is similar to plastic blow molding.
[0081] Figure 3-7 This is a scanning electron microscope image of the cross section of the hollow polyimide fiber prepared in Example 1-5, in which the hollow tube structure of the fiber can be clearly seen.
[0082] For matters not mentioned above, the prior art applies.
[0083] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing a hollow polyimide fiber, characterized in that: The hollow polyimide fiber is prepared by dry spinning a mixed spinning solution consisting of thermoplastic polyimide, polyamic acid and a solvent.
2. The method for preparing a hollow polyimide fiber according to claim 1, characterized in that: The temperature of the dry spinning tunnel is higher than the melting point of the thermoplastic polyimide and the boiling point of the solvent, and the absolute value of the difference between the boiling point of the solvent and the melting point of the thermoplastic polyimide does not exceed 20 degrees Celsius.
3. The method for preparing a hollow polyimide fiber according to claim 1, characterized in that: The solvent is selected from a mixture of one or more of N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone.
4. The method for preparing a hollow polyimide fiber according to claim 1, characterized in that: The synthesis method of the thermoplastic polyimide is a melt polymerization method or a solution polymerization chemical cyclization method.
5. The method for preparing a hollow polyimide fiber according to claim 1, characterized in that: The raw material for synthesizing thermoplastic polyimide, the diamine is selected from one or more of p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, and the dianhydride is selected from one or more of pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride; The raw materials for synthesizing polyamic acid are: the diamine is selected from one or more of p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenylmethane; and the dianhydride is selected from one or more of pyromellitic dianhydride and biphenyltetracarboxylic dianhydride.
6. The method for preparing a hollow polyimide fiber according to claim 1, characterized in that: The specific steps include: S1: Synthesize thermoplastic polyimide by one-step process to make powder or small crystalline particles; S2: dissolving thermoplastic polyimide powder or granules into a thermoplastic polyimide solution using a solvent; S3: synthesizing a polyamic acid solution by solution polymerization; S4: adding the thermoplastic polyimide solution to the polyamic acid solution, mixing them evenly, and degassing to obtain a mixed spinning solution; S5: by controlling the spinning process parameters of the spinneret temperature, the tunnel temperature and the air volume, the mixed spinning solution is subjected to dry spinning to obtain the polyimide primary yarn with a hollow structure; S6: The spun silk is cyclized and drawn at high temperature to obtain hollow polyimide fibers.
7. The method for preparing a hollow polyimide fiber according to claim 6, characterized in that: In the above step S2, the concentration of the thermoplastic polyimide solution is 20%-50%.
8. The method for preparing a hollow polyimide fiber according to claim 6, characterized in that: In the above step S3, the concentration of the polyamic acid solution is 15%-30%.
9. The method for preparing a hollow polyimide fiber according to claim 6, characterized in that: In the above step S5, the temperature of the spinning tunnel is between 150°C and 250°C; the temperature of the spinneret is between 0°C and 50°C.
10. A hollow polyimide fiber prepared by the preparation method according to any one of claims 1 to 9.