CN-119841990-B - Ammoniation method of polyacrylonitrile powder

CN119841990BCN 119841990 BCN119841990 BCN 119841990BCN-119841990-B

Abstract

The invention relates to the technical field of polyacrylonitrile-based carbon fibers, and provides an ammonification method of polyacrylonitrile powder. The method comprises the steps of removing single carboxyl-containing polyacrylonitrile material liquid obtained by precipitation polymerization, and then drying for the first time to obtain carboxyl-containing polyacrylonitrile powder, wherein the carboxyl-containing polyacrylonitrile powder is soaked in an aqueous solution of an ammoniation reagent for ammoniation, and the ammoniation reagent is ammonium salt. The method starts from the source of the spinning solution, the method is simple to operate, has high ammoniation efficiency, can effectively improve the hydrophilicity of the polyacrylonitrile, overcomes the defects of large smell and high toxicity of common liquid amine and gas ammonia, ensures that an ammoniated system is pure and environment-friendly, and further avoids the influence of impurities generated by post-pre-oxidation and carbonization on the performance of the final carbon fiber because the special ammoniated reagent does not introduce miscellaneous elements into the system.

Inventors

FU ZHONGYU
ZHANG HUIXUAN
YAN HUIJIE
LI SONGSONG
GUO WEI
WANG CHUNQI
LIU SHUANG
Mao Bingqi
JIANG YANBO
CHEN HAIJUN

Assignees

长春工业大学

Dates

Publication Date: 20260512
Application Date: 20250120

Claims (7)

1. An ammonification method of polyacrylonitrile powder is characterized by comprising the following steps: Removing single carboxyl-containing polyacrylonitrile feed liquid obtained by precipitation polymerization, and then drying for the first time to obtain carboxyl-containing polyacrylonitrile powder; The carboxyl-containing polyacrylonitrile powder is soaked in an ammonification reagent aqueous solution for ammonification, the ammonification reagent is ammonium salt, the concentration of the ammonification reagent aqueous solution is 0.01 mol/L-5 mol/L, the amino molar quantity of the ammonium salt in the ammonification reagent aqueous solution is greater than or equal to the molar quantity of carboxyl in the ammonified carboxyl-containing polyacrylonitrile powder, the ammonification process further comprises washing the obtained ammonification product and then carrying out second drying, and the ammonium salt comprises one or more of ammonium carbonate, ammonium acetate, ammonium formate and ammonium bicarbonate.
2. The ammonification process according to claim 1, wherein the molar ratio of the amino group in the ammonium salt to the carboxyl group in the carboxyl group-containing polyacrylonitrile powder is 1 to 10:1.
3. The ammonification process according to claim 1, wherein the comonomer used in the precipitation polymerization is a carboxyl group-containing comonomer, and the carboxyl group-containing comonomer comprises one or more of itaconic acid, acrylic acid, methacrylic acid, maleic acid, methyl maleic acid and fumaric acid.
4. The ammonification method according to claim 1, wherein the ammonification temperature is 30-100 ℃ and the ammonification time is 0.5-48 h.
5. The ammonifying process according to claim 1, wherein the process of removing monomers is carried out by pouring the carboxyl group-containing polyacrylonitrile feed solution into deionized water, and then filtering and washing.
6. The ammonifying method according to claim 1, wherein the temperature of the first drying is 40-80 ℃.
7. The ammonifying method according to claim 1, wherein the second drying temperature is 40-80 ℃.

Description

Ammoniation method of polyacrylonitrile powder Technical Field The invention relates to the technical field of polyacrylonitrile-based carbon fibers, in particular to an ammonification method of polyacrylonitrile powder. Background With the development of the fields of aerospace, wind power blades, electric automobiles, pressure vessels and the like, the demand for light and high-strength composite materials is more and more urgent. Carbon fiber is often used with plastic, metal, ceramic and other substrates to make fiber reinforced composites for the preparation of high strength structural materials. The preparation method of the carbon fiber comprises the steps of preparing precursor into precursor through spinning, and preparing the carbon fiber through pre-oxidation and carbonization. The precursor for spinning mainly comprises Polyacrylonitrile (PAN), viscose fiber, asphalt and the like. The polyacrylonitrile-based carbon fiber has the advantages of excellent quality of finished products, simple process and excellent mechanical properties, and becomes the main stream of carbon fiber production. In the production process of the polyacrylonitrile precursor, the coagulation forming of the spinning solution is completed by double diffusion of a solvent and a precipitator and precipitation of polyacrylonitrile molecules. The current spinning methods adopted in industry are mostly wet spinning. However, the solidification double diffusion rate in the wet spinning process is relatively high, so that defects such as macropores, skin-core structures, irregular fiber structures and the like of the polyacrylonitrile fiber are easily caused, the defects are inherited into the polyacrylonitrile fiber and the carbon fiber, and the performance and the application field of the carbon fiber are seriously weakened. The solidification double-diffusion process has a great relationship with the hydrophilicity of the spinning solution, and the improvement of the hydrophilicity of the spinning solution can slow down the solidification forming speed of the spinning solution and reduce the defects of macropores, skin-core structures, irregular fiber structures and the like. Increasing the hydrophilicity of the dope by ammoniating it is an effective means to avoid the above problems. Currently, the main ammoniation modes in the market are divided into 3 modes, namely adding ammonia before polymerization, adding ammonia before single removal after polymerization (adding ammonia after polymerization for short) and adding ammonia in a coagulating bath. The method can improve the hydrophilicity of the spinning solution, but has the defects that 1, ammonia addition before polymerization can produce an obstruction effect on polymerization reaction and simultaneously has adverse effects on mass transfer and heat transfer in the polymerization process. 2. Ammonia is added before single removal after polymerization, and the ammoniation degree is not easy to control. 3. Ammonia is added in the coagulating bath, so that the ammonia in the coagulating bath is not easy to uniformly mix and react with the high-viscosity spinning solution, and the ammoniation efficiency is low. Disclosure of Invention In view of this, the present invention provides an ammonification method for polyacrylonitrile powder. According to the invention, from the source of the spinning solution, the polyacrylonitrile powder after the removal of the monomer is effectively aminated before the spinning solution is prepared, so that the hydrophilicity of the polyacrylonitrile can be effectively improved, and the method is simple to operate and environment-friendly. In order to achieve the above object, the present invention provides the following technical solutions: an ammonification method of polyacrylonitrile powder comprises the following steps: Removing single carboxyl-containing polyacrylonitrile feed liquid obtained by precipitation polymerization, and then drying for the first time to obtain carboxyl-containing polyacrylonitrile powder; and (3) immersing the carboxyl-containing polyacrylonitrile powder into an aqueous solution of an ammoniation reagent for ammoniation, wherein the ammoniation reagent is ammonium salt. Preferably, the ammonium salt comprises one or more of ammonium carbonate, ammonium acetate, ammonium formate and ammonium bicarbonate. Preferably, the concentration of the ammoniation reagent aqueous solution is 0.01 mol/L-5 mol/L. Preferably, the amino molar quantity of the ammonium salt in the ammoniation reagent aqueous solution is more than or equal to the molar quantity of carboxyl in the ammoniated carboxyl-containing polyacrylonitrile powder. Preferably, the molar ratio of the amino group in the ammonium salt to the carboxyl group in the carboxyl-containing polyacrylonitrile powder is 1-10:1, and more preferably 1-5:1. Preferably, the comonomer used for the precipitation polymerization is a carboxyl group-containing comonomer including one o