CN-119841991-B - Preparation method of high molecular weight polyacrylonitrile

Abstract

The invention relates to the technical field of high molecular synthesis and processing, and provides a preparation method of high molecular weight polyacrylonitrile. The invention controls the proportion of the monomer, the initiator and the acidified water, so that the polymerization reaction is carried out under the condition of low monomer concentration, the monomer liquid drop polymerization can be avoided, the generation of solid particles is effectively avoided, and the dissolution difficulty of the high molecular weight polyacrylonitrile in the solution during the preparation of the spinning solution is greatly reduced. Meanwhile, the invention adopts the acidified water as a polymerization medium, is favorable for reducing the viscosity of a polymerization system, realizes equal consumption of copolymerization components, can well solve the phenomenon of scab of a polymerization reaction kettle, and finally obtains the high molecular weight polyacrylonitrile particles with uniform particle size distribution and loose particle surfaces.

Inventors

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

Assignees

• 长春工业大学

Dates

Publication Date

20260508

Application Date

20250120

Claims (8)

1. 1. A preparation method of high molecular weight polyacrylonitrile is characterized by comprising the following raw materials in parts by mass 5-14 Parts of acrylonitrile monomer, 0.18-10 parts of first auxiliary monomer, 0.06-10 parts of second auxiliary monomer, 86-95 parts of acidified water and 0.01-4 parts of initiator; The first auxiliary monomer comprises one or more of vinyl ester monomers, vinyl imidazole, 4-acryloylmorpholine and styrene; The second auxiliary monomer comprises one or more of vinyl acid monomers, vinylamine monomers, vinylamide monomers and ammonium salts of vinyl acid; The viscosity average molecular weight of the high molecular weight polyacrylonitrile is 30-120 ten thousand, and the molecular weight distribution is less than 2; the polymerization reaction comprises the steps of mixing acidified water, an acrylonitrile monomer, a first auxiliary monomer, a second auxiliary monomer and an initiator to obtain a polymerization system, and carrying out the polymerization reaction on the polymerization system, wherein the total concentration of the acrylonitrile monomer, the first auxiliary monomer and the second auxiliary monomer in the polymerization system is 5-10wt%.
2. 2. The production method according to claim 1, wherein the vinyl ester monomer comprises one or more of methyl acrylate, methyl methacrylate, vinyl acetate, propylene acetate, ethyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, cyclohexyl methacrylate, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, dimethyl maleate, dimethyl itaconate, monomethyl itaconate, monoethyl itaconate, mono-n-propyl itaconate, monoisopropyl itaconate, mono-n-butyl itaconate, monoisobutyl itaconate, ethyl 2- (dimethylamino) acrylate, propyl 3- (dimethylamino) acrylate and ethyl acrylate.
3. 3. The production method according to claim 1, wherein the vinyl acid-based monomer comprises one or more of acrylic acid, methacrylic acid, itaconic acid, methyl fumaric acid, 2-butenoic acid, maleic acid, methyl maleic acid, 2-acrylamido-2-methylpropanesulfonic acid, and methylpropanesulfonic acid; The vinylamine monomer comprises one or more of N, N-dimethylallylamine, methylpropenyl sulfonic acid amine and styrenesulfonic acid amine; The vinyl amide monomer comprises one or more of acrylamide, methacrylamide, N-methylol acrylamide and N, N-dimethyl acrylamide; the ammonium salt of a vinyl acid comprises ammonium itaconate.
4. 4. The method of claim 1, wherein the initiator comprises one or more of a water-soluble azo-based initiator, a peroxy-based initiator, a persulfate-based initiator, and a water-soluble redox complex initiation system.
5. 5. The method of producing according to claim 4, wherein the water-soluble azo-based initiator comprises one or more of azobisisobutylamidine hydrochloride, azobisiso Ding Mi, and azobis-methyl N-2-hydroxybutyl propionamide; the peroxygen initiator comprises one or more of hydrogen peroxide and peroxybenzoate; the persulfate initiator comprises one or more of persulfate and persulfate; The water-soluble redox composite initiation system comprises one or more of a persulfate-sulfite system, a benzoyl peroxide-amine system, a hydrogen peroxide-ferric salt system, a lauroyl peroxide-naphthenate system and a persulfate-sulfate system.
6. 6. The preparation method of the water-soluble redox composite initiator according to claim 4 or 5, wherein the dosages of the water-soluble azo initiator, the peroxy initiator and the persulfate initiator are independently 0.1-1% of the weight of the acrylonitrile monomer, the dosage of the oxidant in the water-soluble redox composite initiator system is 0.1-1% of the weight of the acrylonitrile monomer, and the molar ratio of the oxidant to the reducer in the water-soluble redox composite initiator system is 1:0.5-1.5.
7. 7. The preparation method of the acid-base water according to claim 1, wherein the acid-base water is prepared from acid and water, the acid comprises one or more of sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, and the pH value of the acid-base water is 1-6.
8. 8. The method according to claim 1, wherein the polymerization reaction temperature is 40 to 100 ℃.

Description

Preparation method of high molecular weight polyacrylonitrile Technical Field The invention relates to the technical field of high molecular synthesis and processing, in particular to a preparation method of high molecular weight polyacrylonitrile. 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 in combination with plastic, metal, ceramic, etc. matrices to form fiber reinforced composites for the preparation of high strength structural materials, and carbon fiber is therefore one of the engineering materials for high end applications. The raw materials for spinning, namely 'precursor', of the carbon fiber mainly comprise Polyacrylonitrile (PAN), viscose fiber, asphalt and the like. The polyacrylonitrile-based carbon fiber is the main stream of carbon fiber production due to the characteristics of excellent quality of finished products, simple process and excellent mechanical properties. Research shows that the quality of polyacrylonitrile precursor determines the performance of carbon fiber, and the production of high-performance carbon fiber is not separated from high-quality polyacrylonitrile precursor. At present, most of industrial production of polyacrylonitrile adopts homogeneous solution polymerization, namely monomer, initiator and the like are dissolved in an organic solvent for polymerization reaction, the process flow of the method is simple, the quality of the obtained spinning solution is better, but the method has the defects of lower monomer conversion rate, the solvent adopted by the method generally has larger chain transfer constant, the polyacrylonitrile with high average molecular weight is difficult to obtain, and the molecular weight distribution of the obtained polymer is wider. The aqueous phase precipitation polymerization process is to disperse acrylonitrile monomer and initiator into aqueous phase for polymerization reaction. Since polyacrylonitrile is insoluble in water, the polymer formed will continue to precipitate out of the aqueous phase as a precipitate as the polymerization proceeds. Compared with homogeneous solution polymerization, the heterogeneous aqueous phase precipitation polymerization has a complex process flow, but can obtain a polymer with higher molecular weight. At present, solid large particles are easy to generate when aqueous phase precipitation polymerization is carried out industrially, the molecular weight distribution and the dissolution performance of a polymerization product are seriously influenced, and the spinnability of spinning solution and the operability of subsequent pre-oxidation and carbonization are further influenced, so that the improvement of the mechanical properties of polyacrylonitrile fibers and carbon fibers is not facilitated. Meanwhile, another technical problem of aqueous phase precipitation polymerization is that the polymerization product in the polymerization process is easily attached to the wall of the polymerization vessel, a phenomenon called "scarring". Because of the difference between the polymerization environment at the scab and the inside of the kettle, the molecular weight, copolymerization composition and the like of the product at the scab are greatly different from those of the normal product in the kettle, and the molecular weight distribution of the polyacrylonitrile is wider. Disclosure of Invention In view of this, the present invention provides a process for the preparation of high molecular weight polyacrylonitrile. The preparation method provided by the invention can obtain the polyacrylonitrile particles with uniform particle size, narrow particle size distribution and loose particle surfaces and high molecular weight. In order to achieve the above object, the present invention provides the following technical solutions: The preparation method of the high molecular weight polyacrylonitrile comprises the following raw materials, by mass, 5-14 parts of acrylonitrile monomers, 0-10 parts of first auxiliary monomers, 0-10 parts of second auxiliary monomers, 86-95 parts of acidified water and 0.01-4 parts of initiator; The first auxiliary monomer comprises one or more of vinyl ester monomers, vinyl imidazole, 4-acryloylmorpholine and styrene; The second auxiliary monomer comprises one or more of vinyl acid monomers, vinylamine monomers, vinylamide monomers and ammonium salts of vinyl acid; The viscosity average molecular weight of the high molecular weight polyacrylonitrile is 30-120 ten thousand, and the molecular weight distribution is less than 2. Preferably, the vinyl ester monomers include one or more of methyl acrylate, methyl methacrylate, vinyl acetate, propylene acetate, ethyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, cyclohexyl methacrylate, isobutyl a