KR20200084632A - Method for preparing acrylonitrile based polymer - Google Patents

Abstract

The present invention relates to a method for producing a continuous acrylonitrile-based copolymer, comprising a reaction system including two or more reactors. The present invention provides a method for producing an acrylonitrile-based copolymer, comprising: a first polymerization step of a raw material mixture containing an acrylonitrile-based monomer in the presence of a polymerization initiator in a continuous stirred reactor; and a second polymerization step of transferring the firstly polymerized raw material mixture to a static mixer and performing second polymerization in the static mixer, wherein viscosity of the firstly polymerized raw material mixture is 40,000 to 70,000 cP at 45°C.

Description

Manufacturing method of acrylonitrile-based copolymer {METHOD FOR PREPARING ACRYLONITRILE BASED POLYMER}

The present invention relates to a method for producing an acrylonitrile-based copolymer used for the production of carbon fibers, and relates to a method for producing a continuous acrylonitrile-based copolymer including a reaction system including two or more reactors.

Carbon fiber is a fibrous carbon material composed of 90% by weight or more of carbon elements relative to the total weight, and is made of polyacrylonitrile (PAN), a petroleum-coal-based hydrocarbon residue pitch or fiber produced from rayon. It means a fiber obtained by thermally decomposing the precursor of the inert atmosphere.

Carbon fiber is a material that has the structural and organizational properties of carbon, which is a component, and has a fiber shape.It has heat resistance, chemical stability, electrical thermal conductivity, dimensional stability according to low thermal expansion, low density, friction wear characteristics, X-ray permeability, and electromagnetic wave shielding properties. , It has excellent characteristics such as biocompatibility and flexibility, and it is also possible to impart very good adsorption characteristics depending on activation conditions.

On the other hand, acrylonitrile-based polymers are widely used as raw materials for carbon fiber precursors. As a method for producing an acrylonitrile-based polymer, a solution polymerization method is mainly used. In the solution polymerization method, a mixture of an acrylonitrile-based monomer, a polymerization initiator, and a reaction solvent can be used as a spinning solution, and the process is not performed by dissolving an acrylonitrile-based polymer in a spinning solvent to make a spinning dope. It has the advantage of being economical.

On the other hand, in order to improve the productivity of the PAN-based carbon fiber, efforts have been made to improve efficiency in all processes, such as a spinning step, a flameproofing step, or a carbonization step of a carbon fiber precursor. However, when the PAN-based carbon fiber precursor is spun, there are limitations in the limit spinning draft rate and the stretching ratio depending on the solidification structure of the PAN-based polymer solution. As a result, when the spinning speed is increased to improve the productivity, the elongation of the PAN-based carbon fiber is lowered, and when the spinning speed is lowered, the productivity is lowered, and thus there is a problem that it is difficult to achieve both productivity improvement and product performance improvement.

In order to solve these problems, Patent Document 1, PAN-based polymer solution containing a small amount of ultra-high molecular weight components, even when spinning at a high spinning draft rate, it is possible to obtain a good quality precursor fiber without damaging the fiber and mass production of carbon fiber This has the advantage of being possible, and a batch type solution polymerization method has been proposed in this way.

Specifically, by dividing and adding a reagent such as a polymerization initiator in two, polymerization of an ultra high molecular weight component and polymerization of a common molecular weight component are performed in the same reaction solution, thereby easily obtaining a PAN-based polymer solution excellent in sharpness. It is suggested that there is.

However, in order to obtain a polymerization rate of a certain ultra-high molecular weight component, strict control of the timing of the injection of the reagent is required, and when the polymerization is repeated in the same reactor, the residual reagent affects the polymerization specification and the viscosity is high, and the gel in the reactor is high. Since a large amount of production occurs, separate measures such as frequent washing of the reactor are required, and the uniformity of physical properties of the PAN-based polymer produced in a batch type is greatly deteriorated, and there is a problem of quality deviation.

On the other hand, in the case of patent document 2, a method of preparing an acrylonitrile-styrene copolymer by repeating a continuous process two or more times is proposed. In the case of a solution having a high conversion rate and a high viscosity, such as a PAN-based polymer solution, it is continuous. Since the volume of the reactor that performs the food process must be relatively larger, the economic efficiency of the manufacturing process is lowered, and the stirring and the heat removal performance are low, and there is also a problem that a large amount of gel is generated in the reactor.

Therefore, simultaneous improvement of quality improvement and productivity improvement is still in demand.

JP 2008-248219 A KR 1999-0001928 A

The present invention has been devised to solve the above problems, and applies a continuous production method including a reaction system including two or more reactors, but can significantly improve conversion while suppressing deterioration in physical properties, thereby increasing productivity. It is intended to provide a method for producing a greatly increased acrylonitrile-based copolymer.

According to an embodiment of the present invention to solve the above problems, as a method for producing a continuous acrylonitrile-based copolymer comprising a reaction system comprising two or more reactors, in the presence of a polymerization initiator in a continuous stirred reactor , A first polymerization step of primary polymerization of a raw material mixture containing an acrylonitrile-based monomer; And a second polymerization step of transferring the primary polymerized raw material mixture to a static mixer for secondary polymerization in a static mixer, wherein the viscosity of the primary polymerized raw material mixture is 40,000 cP to 70,000 cP at 45°C. A method for producing an acrylonitrile-based copolymer is provided.

According to the method for producing an acrylonitrile-based copolymer of the present invention, it is possible to maximize productivity because it can suppress the deterioration in physical properties of the polymer and greatly improve the conversion rate through a multi-step polymerization reaction using two reactors. And it can provide an acrylonitrile-based copolymer having excellent uniform physical properties.

1 is a process schematic diagram for a process for producing an acrylonitrile-based copolymer according to the present invention.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention.

The terms or words used in the present specification and claims should not be interpreted as being limited to ordinary or dictionary meanings, and the inventor can appropriately define the concept of terms in order to explain his or her invention in the best way. Based on the principle of being present, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

A method for producing an acrylonitrile-based copolymer according to an embodiment of the present invention is a method for producing a continuous acrylonitrile-based copolymer including a reaction system including two or more reactors, a polymerization initiator in a continuous stirred reactor In the presence of, a first polymerization step of primary polymerization of a raw material mixture comprising an acrylonitrile-based monomer; And a second polymerization step of transferring the primary polymerized raw material mixture to a static mixer for secondary polymerization in a static mixer, wherein the viscosity of the primary polymerized raw material mixture is 40,000 cP to 70,000 cP at 45°C. Is done.

According to the above production method of the present invention, an acrylonitrile-based copolymer having uniform physical properties can be obtained, the reaction time can be shortened, and the conversion rate is improved compared to the case of using only a batch polymerization method or a continuous polymerization method. It is possible to prevent the deterioration of physical properties due to the suppression of gel formation, which is a by-product, and thus the productivity can be greatly improved.

Conventionally, in order to polymerize PAN for carbon fiber, a batch polymerization process or a continuous stirring polymerization process was performed alone. However, the batch-type polymerization process has a fast polymerization reaction rate, but has the disadvantage that the uniformity of properties decreases when a gaseous reactant is present. In the case of a continuous process, the uniformity of the physical properties of the polymerized product is excellent, but the batch type There is a disadvantage in that the reaction rate is slower than the process, and if any method goes through the polymerization process alone, there is a problem that the uniformity of physical properties and productivity of the manufacturing process decrease.

Therefore, in the case of the present invention, the polymerization step of the raw material mixture containing the acrylonitrile-based monomer for preparing the acrylonitrile-based copolymer was performed through all other polymerization reactions using two or more reactors. When the polymerization reaction is performed by using two or more reactors as in the present invention, the polymerization reaction rate is fast while considering the viscosity and conversion rate during polymerization of the raw material mixture, and finally the method for producing an acrylonitrile-based copolymer having improved physical property uniformity Can provide

More specifically, in a section having a relatively low polymerization conversion rate and a low viscosity, the uniformity of the polymerization reaction may be improved by using a continuous stirring reactor.

Meanwhile, a static mixer, which is a reactor used in the absence of a gaseous reactant, may be used in a section having a relatively high polymerization conversion rate and a high viscosity. When the polymerization reaction is performed using a static mixer, the heat transfer area per unit volume inside the reactor is larger than that of the continuous stirring reactor, so that the heat removal issue can be alleviated, and the reaction rate is also faster than that of the continuous stirring reactor. It is possible to improve the productivity of the manufacturing process.

Hereinafter, the manufacturing method according to the present invention will be described for each step.

<1st polymerization stage>

First, the first polymerization step is a step of primary polymerization of a raw material mixture containing an acrylonitrile-based monomer in the presence of a polymerization initiator in a continuous stirring reactor.

In the first polymerization step, a raw material mixture containing an acrylonitrile-based monomer starts polymerization in the presence of a polymerization initiator,

The viscosity of the primary polymerized raw material mixture may be 40,000 cP to 70,000 cP at 45°C, preferably 45,000 cP to 65,000 cP at 45°C, and more preferably 50,000 cP to 60,000 cP at 45°C.

In the case of the first polymerization step, a polymerization process performed in a continuous stirring reactor, when the viscosity of the primary polymerized raw material mixture is within the above range, the polymerization conversion rate or the molecular weight distribution of the final polymer is excellent, and the continuous stirring reactor It is possible to prevent the formation of by-products (gels) due to deterioration of stirring and heat removal performance.

The continuous stirring reactor, it is preferable to use a continuous stirring reactor equipped with a stirrer and a jacket so that the heat removal performance can be relatively excellent.

The raw material mixture includes an acrylonitrile-based monomer.

For example, the acrylonitrile-based monomer may be at least one selected from the group consisting of acrylonitrile and methacrylonitrile, and acrylonitrile may be preferable.

In addition, the raw material mixture may further include an organic solvent, for example, the organic solvent may be at least one selected from the group consisting of dimethyl sulfoxide, dimethyl formamide and dimethyl acetamide, of which dimethyl sulfoxide Side may be preferred.

The raw material mixture includes 200 parts by weight to 500 parts by weight of the organic solvent, preferably 240 parts by weight to 400 parts by weight, and more preferably 260 parts by weight to 320 parts by weight based on 100 parts by weight of the acrylonitrile monomer. can do. When the organic solvent is included in the above range, polymerization conversion rate and weight average molecular weight of the raw material mixture may be increased by optimally adjusting the viscosity of the raw material mixture.

Meanwhile, the raw material mixture may further include an additional monomer as a comonomer in addition to the acrylonitrile-based monomer. The comonomer may be, for example, one or more selected from the group consisting of carboxylic acid monomers and (meth)acrylate monomers.

The carboxylic acid-based monomer may be at least one selected from the group consisting of acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, crotonic acid, citraconic acid, maleic acid, and mesaconic acid, and itaconic acid is preferred. The (meth)acrylate-based monomer may be one or more selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate and propyl methacrylate, of which Methyl acrylate is preferred.

The comonomer may be included in an amount of 1 to 10 parts by weight, preferably 1 to 7 parts by weight, and more preferably 1 to 4 parts by weight based on 100 parts by weight of an acrylonitrile-based monomer. If the above-described range is satisfied, not only can the role of lowering the initiation temperature of the oxidation stabilization reaction in the acrylonitrile-based fiber manufacturing process, it is also possible to impart appropriate stretchability to the acrylonitrile-based fiber.

The polymerization reaction may be performed in the presence of a polymerization initiator, and the polymerization initiator is for initiating a polymerization reaction between acrylonitrile-based monomers in a raw material mixture or comonomers that may be added.

For example, as a polymerization initiator, azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis (2,4-dimethyl Valeronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis[N-( 2-propenyl)-2-methyl propionamide, [(cyano-1-methyl ethyl)azo]formamide, 2 2'-azobis(N-butyl-2-methyl propion amide), 2,2'- Azobis (N-cyclohexyl-2-methyl propion amide) or the like can be used, among which azobisisobutyronitrile is particularly preferred.

The polymerization initiator may be added in 0.2 parts by weight to 2.0 parts by weight, preferably 0.3 parts by weight to 1.0 parts by weight, and more preferably 0.4 parts by weight to 0.8 parts by weight based on 100 parts by weight of the acrylonitrile-based monomer. When the polymerization initiator satisfies the above-described range, the final polymerization conversion rate of the obtained polymer can be improved.

<2nd polymerization stage>

Next, the second polymerization step is a step of transferring the primary polymerized raw material mixture to a static mixer to perform secondary polymerization in the static mixer.

In the first polymerization step, a continuous stirring reactor is used, while in the second polymerization step, a second mixer is performed using a static mixer.

As mentioned above, when the polymerization reaction is performed only through the continuous stirring reaction, the polymerization reaction rate is slower than when using a static mixer, and when the viscosity of the mixture for the raw material rises as the polymerization reaction proceeds, stirring And the heat removal performance is lowered by-product (gel) may be generated in the reactor. On the other hand, when the polymerization reaction is performed through only a static mixer, physical property degradation due to a temperature gradient may occur in the front part of the reactor.

Therefore, according to an embodiment of the present invention, when the polymerization reaction proceeds, the viscosity range is varied, and when the mixture for the raw material is polymerized in the first polymerization step, the viscosity and polymerization conversion rate of a certain level or higher are transferred to a static mixer. After that, the second polymerization step was performed.

At this time, the viscosity of the first polymerized raw material mixture may be 40,000 cP to 70,000 cP at 45°C, preferably 45,000 cP to 65,000 cP at 45°C, more preferably 50,000 cP to 60,000 cP at 45°C. .

In addition, when the primary polymerized raw material mixture is transferred to the static mixer, when the polymerization conversion ratio of the primary polymerized raw material mixture is 60% to 80%, preferably 70% to 80%, more preferably 70 % To 75%.

If the polymerization conversion rate of the primary polymerized raw material mixture is transferred when the polymerization conversion rate is less than the above range, the yield of the final product, an acrylonitrile-based copolymer, is too low and the polymerization reaction must be additionally performed, so productivity decreases. Can. As the second polymerization reaction is performed longer, there is also a fear that the physical properties of the copolymer are deteriorated.

On the other hand, if the polymerization conversion rate of the primary polymerized raw material mixture is transferred when the polymerization conversion rate exceeds the above range, the stirring and de-heating performance decreases due to the viscosity increase of the raw material mixture in the continuous stirring reactor, resulting in a byproduct gel in the reactor. This is generated, the reactor contamination can be serious, there is a problem that the reactor volume must be increased to increase the reaction volume of the continuous stirred reactor. Therefore, in order to solve the above problems, it is preferable that the time point at which the primary polymerized raw material mixture is transferred to the static mixer should be the polymerization conversion rate of the primary polymerized raw material mixture within the above range.

On the other hand, in the second polymerization step, the polymerization initiator is additionally added secondly. At this time, the polymerization initiator that is secondly introduced may be used in the same manner as the above-described polymerization initiator.

The polymerization initiator to be added may be added in a mixed state with an organic solvent, wherein the organic solvent is the same as the organic solvent described above.

At this time, the polymerization initiator additionally added in the second polymerization step is 0.2 parts by weight to 2.0 parts by weight, preferably 0.3 parts by weight to 1.0 parts by weight, and more preferably 0.4 parts by weight to 0.8 parts by weight based on 100 parts by weight of the raw material mixture. It may be parts by weight. If the above-mentioned ranges are satisfied, solution polymerization can be easily performed without lowering the polymerization conversion rate of the obtained polymer.

In addition, in the second polymerization step, it may be necessary to control the polymerization reaction temperature. For example, the reaction temperature of the second polymerization step may be preferably 60° C. to 80° C., and if the above range is satisfied, the molecular weight distribution may be narrowed (it may be small), thereby deteriorating physical properties. And can increase the conversion rate.

After being transferred to the static mixer, the viscosity of the secondary polymerized raw material mixture is 30,000 cP to 60,000 cP at 45°C, preferably 35,000 cP to 55,000 cP at 45°C, more preferably 40,000 cP to 50,000 cP at 45°C. Can be

At this time, the polymerization conversion rate of the secondary polymerized raw material mixture may be 90% or more, preferably 90% to 95%, more preferably 90% to 93%.

When the secondary polymerized raw material mixture satisfies the viscosity range and polymerization conversion range, it can be used as a spinning solution for acrylonitrile-based fiber production without additional treatment such as mixing a spinning solvent. Even when the secondary polymerized raw material mixture is used directly as a spinning solution, it is also possible to prevent the elongation of the produced fiber from being deteriorated without causing defects in the process, such as clogging of the spinning outlet.

Meanwhile, the molecular weight distribution according to Equation 1 below of the secondary polymerized raw material mixture may be 2.0 Mw/Mn to 4.0 Mw/Mn, preferably 2.4 Mw/Mn to 3.0 Mw/Mn.

[Equation 1]

Molecular weight distribution = weight average molecular weight (Mw)/number average molecular weight (Mn)

When the secondary polymerized raw material mixture has a molecular weight distribution in the above range, the conversion rate is excellent, but a decrease in the molecular weight distribution value is suppressed, and thus there is an advantage that the physical property decrease can be suppressed.

Example

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

Example 1

A reaction solution was prepared by uniformly dissolving 100 parts by weight of a monomer mixture obtained by mixing acrylonitrile and itaconic acid in a molar ratio of 99.47:0.53 to 279.0 parts by weight of dimethyl sulfoxide and 0.6 parts by weight of azobisisobutyronitrile as a radical polymerization initiator. .

The reaction solution was introduced into a raw material mixture tank 1 equipped with a stirrer, and nitrogen was purged to remove dissolved oxygen.

Subsequently, the reaction solution was added to a nitrogen-stirred continuous stirring reactor (CSTR) 3 in advance using a raw material mixture transfer pump 2, and the temperature of the reaction solution in the reactor was maintained at 68°C.

Subsequently, when the reaction solution is started to be added to the continuous stirring reactor (CSTR), the reaction solution is withdrawn from the lower part of the reactor using a pump after 10 hours have elapsed, and then, using the first polymerization material transfer pump (4), It was put into the mixer.

At the same time, the radical polymerization initiator solution (azobisisobutyronitrile compared to 100 parts by weight of the radical polymerization initiator solution is included in 0.6 parts by weight) corresponding to 100 parts by weight of the reaction solution flow rate is also included in the polymerization initiator solution tank (5) It was put into the static mixer 7 through the polymerization initiator solution transfer pump 6 together. At this time, the temperature of the reaction solution in the static mixer 7 was maintained at 75°C, and the reaction solution was added until the residence time in the static mixer 7 became 3 hours.

Thereafter, when the temperature, flow rate, stirrer load, and pressure of the static mixer 7 in the static mixer 7 become constant, it is determined that the steady state has been reached, and then an acrylonitrile-based copolymer at the rear end of the static mixer 7 A solution was obtained.

The polymerization conversion rate in the continuous stirring reactor (CSTR) 3 was 75.1%, the viscosity was 55,700 cp at 45°C, and the conversion rate of the acrylonitrile-based copolymer obtained at the rear stage of the static mixer 7 was 91.9%, 45°C. The viscosity was 37,100 cp. The process at this time is also shown in FIG. 1.

Example 2

An acrylonitrile-based copolymer was prepared in the same manner as in Example 1, except that the polymerization conversion rate in the continuous stirring reactor (CSTR) (3) was adjusted to be 72.3% and the viscosity was 51,500 cP at 45°C. .

Example 3

The same as in Example 1, except that the temperature in the static mixer 7 was adjusted to 80°C so that the polymerization conversion rate in the static mixer 7 was 93.2% and the viscosity was 45,700 cP at 45°C. A nitrile-based copolymer was prepared.

Example 4

The same as in Example 1, except that the temperature in the static mixer 7 was adjusted to 85° C. so that the polymerization conversion rate in the static mixer 7 was 94% and the viscosity was 42,300 cP at 45°C. A nitrile-based copolymer was prepared.

[Comparative example]

Comparative Example 1

A reaction solution was prepared by uniformly dissolving 100 parts by weight of a monomer mixture obtained by mixing acrylonitrile and itaconic acid in a molar ratio of 99.47:0.53 to 279.0 parts by weight of dimethyl sulfoxide and 0.6 parts by weight of azobisisobutyronitrile as a radical polymerization initiator. .

The reaction solution was introduced into a raw material mixing vessel equipped with a stirrer, and nitrogen was purged to remove dissolved oxygen.

Subsequently, the reaction solution was added to the nitrogen-substituted first continuous stirring reactor (CSTR) at a predetermined flow rate using a pump, and the temperature of the reactants in the reactor was maintained at 68°C.

Subsequently, at the time 10 hours after the start of injecting the reaction solution into the first continuous stirring reactor (CSTR), the reaction solution was withdrawn from the lower part of the reactor using a pump, and this was followed by the second continuous stirring reactor (CSTR). Was put in.

At the same time, a polymerization initiator solution corresponding to 100 parts by weight compared to 100 parts by weight of the reaction solution in the second continuous stirring reactor (CSTR) (0.8 parts by weight of azobisisobutyronitrile compared to 100 parts by weight of the polymerization initiator solution) Was added to the static mixer using a pump. At this time, the temperature of the reaction solution in the second continuous stirring reactor (CSTR) was maintained at 75° C., and the reaction solution was retained for 3 hours.

The finally obtained acrylonitrile-based copolymer had a polymerization conversion rate of 86.0% and a viscosity of 30,500 cp at 45°C.

Comparative Example 2

An acrylonitrile-based copolymer was prepared in the same manner as in Comparative Example 1, except that the residence time was 4.5 hours after being introduced into the second continuous stirring reactor (CSTR).

Comparative Example 3

An acrylonitrile-based copolymer was prepared in the same manner as in Comparative Example 1, except that the residence time was 7.5 hours after being introduced into the second continuous stirring reactor (CSTR).

Comparative Example 4

The polymerization conversion rate in the continuous stirring reactor (CSTR) was adjusted to 71.8% and the viscosity to be 57,910 cP at 45° C., and the acrylonitrile-based air was the same as in Example 1, except that a static mixer was not used. Copolymers were prepared.

Experimental Example 1

The polymerization conversion and molecular weight distribution (PDI: Mw/Mn) of the acrylonitrile-based copolymers prepared in Examples and Comparative Examples were measured and are shown in Table 1 below.

1) polymerization conversion rate

0.5 g of the obtained polymer solution was precipitated in water, washed with hot water and dried under reduced pressure at 120° C. for 2 hours. The weight of the dried resin was measured to measure the content of solids, and polymerization conversion was measured by the following equation.

Polymerization conversion rate (%): (measured solid content)/ (content of solid content per 0.5 g of reaction solution calculated by the ratio of solid content and solvent added in the reactor)Х100

2) Molecular weight distribution (PDI)

The obtained polymer solution was measured for weight average molecular weight (Mw) and number average molecular weight (Mn) using GPC (Gel Permeation Chromatography) under the following conditions, and the molecular weight distribution was calculated.

Column: PLmixed B Х 2, solvent: DMF/0.05 M LiBr (0.45 μm Filtered), flow rate: 1.0 mL/min, sample concentration: 4.0 mg/mL, injection volume: 100 μl, column temperature: 65, Detector: Waters RI Detector , Standard: PMMA)

CSTR residence time Static mixer residence time Polymerization conversion rate
(%) Molecular weight (Mw) Molecular weight distribution
(Mw/Mn) Example 1 10 3 91.9 303,000 2.76 Example 2 9 3 91.5 299,000 2.81 Example 3 10 3 93.2 305,000 3.19 Example 4 10 3 94.0 295,000 3.42 Comparative Example 1 10 3 86.0 313,000 3.14 Comparative Example 2 10 4.5 86.9 260,000 3.01 Comparative Example 3 10 7.5 88.1 280,000 3.20 Comparative Example 4 9 3 71.8 375,000 2.00

Referring to Table 1, it can be seen that the polymerization conversion rate of the acrylonitrile-based copolymer prepared according to the embodiment is improved.

1. Raw material mixture tank
2. Raw material mixture transfer pump
3. Continuous Stirred Reactor (CSTR)
4. First polymerization pump
5. Polymerization initiator solution tank
6. Polymerization initiator solution transfer pump
7. Static Mixer

Claims (7)

As a method for producing a continuous acrylonitrile-based copolymer comprising a reaction system comprising two or more reactors,
A first polymerization step of primaryly polymerizing a raw material mixture containing an acrylonitrile-based monomer in the presence of a polymerization initiator in a continuous stirring reactor; And
Including a second polymerization step of transferring the primary polymerized raw material mixture to a static mixer to perform secondary polymerization in the static mixer;
The viscosity of the primary polymerized raw material mixture is 40,000 cP to 70,000 cP at 45°C.
According to claim 1,
The viscosity of the secondary polymerized raw material mixture is 30,000 cP to 60,000 cP at 45°C.
According to claim 1,

A method for producing an acrylonitrile-based copolymer, wherein when the primary polymerized raw material mixture is transferred to a static mixer, the polymerization conversion rate of the primary polymerized raw material mixture is 60% to 80%.
According to claim 3,
A method for producing an acrylonitrile-based copolymer, wherein the point of time when the primary polymerized raw material mixture is transferred to a static mixer is when the polymerization conversion rate of the primary polymerized raw material mixture is 70% to 80%.
According to claim 1,
The method for producing an acrylonitrile-based copolymer having a polymerization conversion ratio of the secondary polymerized raw material mixture of 90% or more.
According to claim 1,
A method for preparing an acrylonitrile-based copolymer having a molecular weight distribution according to Equation 1 below of the secondary polymerized raw material mixture is 2.0 Mw/Mn to 4.0 Mw/Mn:
[Equation 1]
Molecular weight distribution = weight average molecular weight (Mw)/number average molecular weight (Mn)
The method of claim 6,
Method for producing an acrylonitrile-based copolymer having a weight average molecular weight of the secondary polymerized raw material mixture is 250,000 Mw to 350,000 Mw.

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