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A kind of three-step mixed imidization method for preparing polyimide fiber

A polyimide fiber, imidization technology, applied in the field of materials, can solve the problems of low degree of imidization of polyimide fibers, decreased fiber performance, fiber surface defects, etc., to improve the degree of imidization, mechanical Effects of improved performance and improved fiber orientation

Active Publication Date: 2019-11-22
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In addition, in the traditional polyamic acid (PAA) wet spinning process, in the prior art, chemical imidization agents are mostly added to the polyamic acid spinning solution, and then thermal imidization is performed to obtain polyimide fibers. , but because polyimide is insoluble in most organic solvents such as DMAc, DMF, NMP, etc., the amount of chemical imidization reagents is less, and the degree of imidization of polyimide fibers is relatively low, so the mechanical properties are also low. poor
Another existing technology is thermal imidization first, and then chemical imidization to obtain polyimide fibers, but since the chemical imidization process in this method will remove small molecule water, resulting in fiber surface defects, the same will degrade the fiber performance

Method used

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  • A kind of three-step mixed imidization method for preparing polyimide fiber
  • A kind of three-step mixed imidization method for preparing polyimide fiber
  • A kind of three-step mixed imidization method for preparing polyimide fiber

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] (1) PMDA and ODA are added in the NMP solvent, stirred, condensation polymerization takes place, obtains polyamic acid spinning solution, solid content is 5%;

[0034] (2) The polyamic acid spinning solution is spun according to the wet spinning process, and the spinning solution is directly passed through the coagulation bath (the volume fraction of DMAc is 5%) after being extruded from the spinneret under the nitrogen pressure of 0.3MPa, Wash with water, and dry the polyamic acid precursor fibers through a tube furnace at 100°C at a constant speed for 3 minutes;

[0035] (3) Pass the polyamic acid precursor fibers through a tube furnace at 150°C at a constant speed for 2 minutes to obtain partially imidized fibers;

[0036] (4) The above-mentioned fibers were soaked in a solution of 1:1 of acetic anhydride / pyridine for 16 hours to perform chemical imidization;

[0037] (5) Dry the fiber obtained in the previous step through a tube furnace at 100°C at a uniform speed ...

Embodiment 2

[0042] (1) BPDA and ODA are added to the DMAc solvent, stirred, and condensation polymerization takes place to obtain a polyamic acid spinning solution with a solid content of 20%;

[0043] (2) The polyamic acid spinning solution is spun according to the wet spinning process, and the spinning solution is directly passed through the coagulation bath (the volume fraction of DMAc is 6%) after being extruded from the spinneret under the nitrogen pressure of 0.2MPa, Wash with water, and dry the polyamic acid precursor fibers through a tube furnace at 60°C at a constant speed for 3 minutes;

[0044] (3) Pass the polyamic acid precursor fibers through a tube furnace at 260°C at a constant speed for 2 minutes to obtain partially imidized fibers;

[0045] (4) Soak the above fibers in a solution of acetic anhydride / pyridine at a ratio of 1:1 for 12 hours for chemical imidization;

[0046](5) Dry the fiber obtained in the previous step through a tube furnace at 60°C at a uniform speed f...

Embodiment 3

[0052] (1) Add the BPDA / PDA / ODA ratio of 10 / 7 / 3 into the DMAc solvent, stir, and undergo condensation polymerization to obtain a polyamic acid spinning solution with a solid content of 10%;

[0053] (2) The polyamic acid spinning solution is spun according to the wet spinning process, and the spinning solution is directly passed through the coagulation bath (the volume fraction of DMAc is 7%) after being extruded from the spinneret under the nitrogen pressure of 0.25MPa, Washing with water, passing the polyamic acid precursor fiber through a tube furnace at 80°C at a constant speed for 2 minutes;

[0054] (3) Pass the polyamic acid precursor fibers through a tube furnace at 260°C at a constant speed for 1 min to obtain partially imidized fibers;

[0055] (4) Soak the above fibers in a solution of acetic anhydride / pyridine at a ratio of 2:1 for 16 hours to carry out chemical imidization;

[0056] (5) Dry the fiber obtained in the previous step through a tube furnace at 80°C at...

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Abstract

The invention relates to a method for preparing polyimide fiber by combining a three-step method and imidization. The method comprises the following steps: a dianhydride monomer and a diamines monomer are subjected to a condensation polymerization reaction in a reaction solvent to obtain a polyamide acid spinning solution; according to a wet spinning technology, the spinning solution is extruded through a spinning head and is subjected to coagulation bath, washing, and drying to obtain the polyamide acid fiber; then primary heat treatment is carried out to obtain partially imidized fiber; fiber is infiltrated in an acetic anhydride / pyridine solution for chemical imidization; and finally, steps of drying and further thermal cyclization are carried out to obtain the polyimide fiber. According to the invention, the chemical imidization process is added in a traditional thermal imidization process, imidization degree of the fiber is increased, at the same time, a ring-closure reaction in a tubular furnace is reduced by the chemical imidization, draw ratio is increased, fiber orientation degree is increased, so that the mechanical properties of the polyimide fiber are greatly increased.

Description

technical field [0001] The invention belongs to the technical field of materials, and in particular relates to a method for preparing polyimide fibers through three-step mixed imidization. Background technique [0002] Polyimide is a polymer material with excellent chemical stability. It has good mechanical properties and heat resistance, outstanding dielectric properties and radiation resistance, and is widely used in aviation, aerospace, microelectronics, and separation membranes. Key materials in various fields such as lasers and lasers. [0003] However, with the development of science and technology, higher and more stringent requirements are put forward for materials in actual use and application. How to improve the mechanical properties of fibers has attracted widespread attention. [0004] At present, polyimide (PI) fibers are mainly obtained by polyamic acid (PAA) wet spinning and thermal cyclization to obtain polyimide fibers. However, due to the heat treatment p...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): D01F6/78C08G73/10
CPCC08G73/1021C08G73/1067C08G73/1071D01F6/78
Inventor 牛鸿庆刘铭张梦颖武德珍
Owner BEIJING UNIV OF CHEM TECH
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