KR20200025826A - Manufacturing method of polyacrylonitrile - Google Patents

Abstract

The present application relates to a method for manufacturing polyacrylonitrile. The method according to the present application can manufacture, at a high conversion rate, polyacrylonitrile which has a high molecular weight and a narrow molecular weight distribution to be suitable for a manufacturing process of carbon fiber, and the like. The method for manufacturing polyacrylonitrile includes a step of polymerizing a monomer component comprising acrylonitrile in the presence of a compound represented by formula 1.

Description

Manufacturing method of polyacrylonitrile {MANUFACTURING METHOD OF POLYACRYLONITRILE}

The present application relates to a process for producing polyacrylonitrile having high molecular weight and narrow molecular weight distribution with high conversion, polyacrylonitrile thus produced and its use.

Carbon fiber is widely applied in various technical fields such as aerospace and wind energy generation because of its high specific strength and rigidity, high chemical resistance and low thermal expansion. Typically, carbon fibers are made from polyacrylonitrile. As a conventional method for producing polyacrylonitrile, free radical polymerization can be used. On the other hand, polyacrylonitrile prepared through this method has a relatively high polydispersity index (PDI). The high polydispersity index of the polymer means that the polymer comprises polymerized units having various chain lengths. In addition, when the polymer includes a unit having a molecular weight that is too high or a unit having a molecular weight that is too low, molecular bonds are generated in the polymer, so that the polymer fiber produced using a spinning process or the like degrades properties such as mechanical properties. There is a problem. That is, in the case of polyacrylonitrile prepared using a conventional free radical polymerization method, since the polydispersity index is high, there is a problem that the mechanical properties of the carbon fiber produced by spinning it are lowered.

In order to solve such a problem, Patent Document 1 is prepared by a reversible addition-fragmentation chain transfer (RAFT) polymerization method, a method for polymerizing polyacrylonitrile having a narrow polydispersity is proposed. There is a bar. However, the polyacrylonitrile thus prepared has a weak mechanical strength due to its low molecular weight.

On the other hand, Patent Document 2 suggests that the higher the molecular weight of polyacrylonitrile, the stronger its mechanical strength is. That is, it can be seen that in order to apply the polyacrylonitrile to the carbon fiber manufacturing process, it must also have a molecular weight of at least a certain level.

Typically, in the case of preparing the polymer using the RAFT polymerization method, the molecular weight of the prepared polymer is adjusted according to the concentration of the chain transfer agent used therein. The lower the concentration of the chain transfer agent, the higher the molecular weight of the polymer, and the higher the concentration, the lower the molecular weight of the polymer. In addition, the polymer should be polymerized by adding a polymerization initiator of a predetermined concentration to the equivalent weight of the chain transfer agent, and the polymerization conversion rate increases as the content of the chain transfer agent increases. That is, when the chain transfer agent content is relatively decreased for polymer polymerization having a high molecular weight, there is a problem that the polymerization conversion rate is decreased accordingly. That is, while using a RAFT polymerization method, a study on a method for achieving a high molecular weight, a narrow polydispersity index and a high conversion rate is required.

On the other hand, Patent Document 3 discloses an emulsion polymerization method of a fluoromonomer as a RAFT polymerization method using a chain transfer agent having two terminal functional groups in one molecule. When the polymer is polymerized using the emulsion polymerization method, the polymer may be synthesized at a high molecular weight and a high conversion rate, but it is difficult to remove the surfactant used in the emulsion polymerization. In addition, these surfactants are likely to act as defects in the subsequent carbon fiber manufacturing process, specifically in the spinning or firing process of the polymer. The polymer synthesized through emulsion polymerization is present in the form of particles dispersed in an aqueous solution, which is not suitable for the wet spinning process which is a typical process in the carbon fiber manufacturing process. In other words, the polyacrylonitrile prepared by the emulsion polymerization method has a problem that can not play a role as a precursor of the carbon fiber.

Republic of Korea Patent Publication No. 10-2016-0103013 US Patent 4658004 Japanese Patent Laid-Open No. 2017-515948

The present application is to provide a method for producing a high conversion of polyacrylonitrile having a high molecular weight, low polydispersity index by polymerizing a monomer component comprising acrylonitrile in the presence of a compound of a predetermined structure

In the present application, the term alkyl group may mean an alkyl group having 1 to 15 carbon atoms, 1 to 10 carbon atoms, and 1 to 4 carbon atoms, unless otherwise specified. The alkyl group may be linear, branched, or cyclic, and may be optionally substituted with one or more substituents.

In the present application, the term alkenyl group or alkynyl group is an alkenyl group or alkynyl group having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, unless otherwise specified. Can mean. The alkenyl group or alkynyl group may be linear, branched or cyclic, and may be optionally substituted with one or more substituents.

In the present application, the term alkylene group may mean an alkylene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless otherwise specified. The alkylene group may be a straight chain, branched or cyclic alkylene group, and may be optionally substituted with one or more substituents.

In the present application, the term alkenylene group or alkynylene group is an alkenylene group or alkoxy having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, unless otherwise specified. It may mean a nylene group. The alkenylene group or alkynylene group may be linear, branched or cyclic, and may be optionally substituted with one or more substituents.

In the present application, unless otherwise specified, the term aryl group or arylene group is one benzene ring structure, two or more benzene rings are connected while sharing one or two carbon atoms, or by any linker It may mean a monovalent or divalent residue derived from a compound or a derivative thereof including the structure to which it is linked. Unless otherwise specified, the aryl group or arylene group may be, for example, an aryl group having 6 to 30 carbon atoms, 6 to 25 carbon atoms, 6 to 21 carbon atoms, 6 to 18 carbon atoms, or 6 to 13 carbon atoms.

In the present application, the term single bond may refer to a case where no separate atom exists at a corresponding site. For example, in the structure represented by A-B-C, when B is a single bond, there is no separate atom at the site represented by B, and A and C are directly connected to form a structure represented by A-C.

Polyacrylonitrile is formed by the polymerization reaction of an acrylonitrile monomer. In addition, the higher the molecular weight of polyacrylonitrile and the narrower the polydispersity index, the easier the application of carbon fiber to the precursor. When the compound of the structure is used as a chain transfer agent in a reversible addition-fragmentation chain transfer (RAFT) polymerization method, the inventors have found that polyacrylonitrile having a high molecular weight and a narrow polydispersity index is high. It has been found that it can be produced at a conversion rate, which leads to the present invention.

Hereinafter, the present application will be described in more detail.

The present application is directed to a process for preparing polyacrylonitrile. The method for producing polyacrylonitrile according to the present application is carried out by a RAFT polymerization method, and a chain transfer agent applied to the RAFT polymerization method is used to carry out the method. Specifically, in the present application, the chain transfer agent may be collectively referred to as a 'RAFT agent', which forms a dormant stage of the radical chain in which a chain reaction of a certain monomer occurs, so that propagation of radicals and radicals It can be used to control the rate of formation. In addition, the RAFT formulations can reach an equilibrium state between the active chain and the dormant chain in a short time, so that the prepared polymer has a narrow molecular weight distribution.

An exemplary embodiment of the present application provides a method of preparing polyacrylonitrile, which comprises polymerizing a monomer component including acrylonitrile in the presence of a compound represented by Formula 1 below:

[Formula 1]

In formula (1), A is an oxygen atom, a sulfur atom, -S (= O) _2- , an alkylene group, an alkenylene group, an alkynylene group, an arylene group, -C (= O) -X _1- , or -X ₁ -C (= O)-, wherein X ₁ is a single bond, oxygen atom, sulfur atom, alkylene group, alkenylene group, alkynylene group, or arylene group, Z ₁ and Z ₂ are each independently, It is a noalkyl group.

In the present application, the compound represented by Chemical Formula 1 is used as a chain transfer agent, specifically, a RAFT agent, such that the polyacrylonitrile has a relatively high molecular weight and a narrow polydispersity index. That is, by using a compound having a structure in which two or more trithiocarbonyl functional groups are contained in one molecule as shown in Chemical Formula 1 and the trithiocarbonyl functional group is bonded to the compound represented by A as a RAFT agent, Polyacrylonitrile having a narrow polydispersity index can be polymerized with high conversion. On the other hand, when preparing a polyacrylonitrile using a compound containing only one trithiocarbonyl functional group in one molecule as a RAFT formulation, the molecular weight is low, there is a problem that does not secure sufficient mechanical strength. In addition, even if two or more trithiocarbonyl functional groups are included in one molecule, the conversion rate of polyacrylonitrile may be reduced when a compound directly bonded to the RAFT agent is used in the absence of a separate linker. There is a problem of rapidly decreasing. The present application can produce polyacrylonitrile by a living radical polymerization method, specifically, a RAFT polymerization method, in the presence of a compound represented by the above formula. In addition, the effect by the RAFT agent may be particularly dependent on Z ₁ and Z ₂ bound thereto. In addition, the Z ₁ and Z ₂ can control the stability of the reactivity by the carbon = sulfur double bond in the RAFT formulation, and may affect the rate of addition and fragmentation of monomer radicals.

In Formula 1, A is specifically -S (= O) _2- , an alkylene group, an alkenylene group, an alkynylene group, an arylene group, -C (= O) -X _1- , or -X ₁ -C ( = O)-, wherein X ₁ may be a single bond, an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an alkynylene group, or an arylene group, and more specifically, an alkylene group, an alkenylene group, or an alkynyl group. It may be an ethylene group, an arylene group, and more specifically, may be an alkylene group.

In addition, A of Formula 1 may be an alkylene group having 8 to 20 carbon atoms. Specifically, A in Formula 1 may be an alkylene group having 9 or more carbon atoms, or 10 or more carbon atoms, and an alkylene group having 19 or less carbon atoms, 16 or less, 14 or less carbon atoms, or 12 or less carbon atoms.

In Formula 1, Z ₁ and Z _{2 which} are each independently a cyanoalkyl group may be the same as or different from each other. The cyanoalkyl group may mean that a cyano group is bonded to an alkyl group, and may optionally mean that one or more elements or substituents are further bonded. The element or substituent that may be bonded to the cyanoalkyl group may be hydrogen, alkenyl group, alkynyl group, hydroxy group, phenyl group, benzyl group, or carboxy group.

Z ₁ and Z ₂ in Formula 1 may each independently be a cyanoalkyl group having a branched alkyl group having 1 to 8 carbon atoms. Specifically, Z ₁ and Z ₂ of Formula 1 may each independently be a cyano alkyl group having a branched alkyl group having 2 or more, 3 or more, or 4 or more carbon atoms, and a powder having 7 or less, 6 or less, or 5 or less carbon atoms. It may be a cyanoalkyl group having a topographic alkyl group.

In one embodiment of the present application, the polyacrylonitrile may be to polymerize a monomer component including acrylonitrile in the presence of a compound represented by Formula 1-1:

[Formula 1-1]

The compound of Formula 1 may be present in a ratio of 0.2 mol or less, specifically 0.15 mol or less, 0.10 mol or less, or 0.05 mol or less with respect to 100 mol of the total monomers of the monomer component. The lower limit of the content of the compound of Formula 1 is not particularly limited, but may be, for example, more than 0 moles, 0.01 moles or more, or 0.03 moles or more relative to 100 moles of the total monomers of the monomer component. When the compound of Formula 1 is present within the above range, polyacrylonitrile having a high molecular weight and a low polydispersity index may be polymerized at a high conversion rate.

The monomer component may further comprise a comonomer for the acrylonitrile. As used herein, the term comonomer refers to a monomer that is different from any monomer and that can be mixed with or polymerized with the monomer to form a copolymer. That is, the polyacrylonitrile may be a copolymer of acrylonitrile and the comonomer.

The comonomer is at least one of vinyl acid, vinyl ester, and vinyl derivative, specifically methacrylic acid, acrylic acid, itaconic acid, methacrylate, methyl methacrylate, vinyl acetate, ethyl acrylate, butyl acrylate, It may include at least one of ethyl methacrylate, vinyl amidazole, acrylamide and diacetone acrylamide, but the type thereof is not particularly limited, and may be copolymerized with an acrylonitrile monomer to form polyacrylonitrile. If so, it can be freely selected from known ones. The content of the comonomer may be 0.5 mol% or more, 0.9 mol% or more, or 1.3 mol% or more, 5 mol% or less, 4 mol% or less, 3 mol% or less, based on the total amount of acrylonitrile monomer and comonomer, Or 2 mol% or less, but is not particularly limited.

The monomer component may include 80 mol% or more of acrylonitrile. Specifically, the monomer component may include at least 85 mol%, at least 90 mol%, or at least 95 mol% of acrylonitrile, and may include less than 100 mol%, or up to 99 mol%. That is, the polyacrylonitrile may include acrylonitrile as a main component.

The manufacturing method of the polyacrylonitrile of this application may specifically be solution polymerization of an acrylonitrile monomer and a comonomer. That is, the monomer component according to one embodiment of the present invention may further include a solvent. In addition, the solvent may include dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, ethylene carbonate, zinc chloride, sodium thiocyanate, and an aqueous solution thereof, and the like. Is not particularly limited. In addition, the content of the solvent may be included in the monomer component in an amount within the range of 70 parts by weight to 95 parts by weight relative to the total 100 parts by weight of the monomer component including the solvent. Specifically, the content of the solvent may be 75 parts by weight or more, based on 100 parts by weight of the total of the monomer components including the solvent. In addition, the content of the solvent may be 100 parts by weight or more, and may be 90 parts by weight or less, 85 parts by weight or less, or 80 parts by weight or less in total of the monomer components including the solvent.

The method for preparing polyacrylonitrile of the present application may not be performed by emulsion polymerization. That is, the polymerization may be carried out in the absence of a surfactant. The polyacrylonitrile prepared by the emulsion polymerization method remains a surfactant, and the surfactant may only act as a cause of deterioration of the carbon fiber when the polyacrylonitrile is subsequently applied to the carbon fiber manufacturing process. This is because there is a problem that the removal is not easy.

The method for preparing polyacrylonitrile of the present application may be performed by radical polymerization. In other words, the polymerization can be carried out in the presence of a radical initiator. Specifically, the step of polymerizing the monomer component in the present application may be to induce a polymerization reaction of acrylonitrile by heating the monomer component, and then adding a radical initiator to the heated monomer component. More specifically, the step of polymerizing the monomer component may be to induce a polymerization reaction by heating the monomer component to a temperature in the range of 40 ℃ to 85 ℃, and then adding a radical initiator to the heated monomer component. Even more specifically, the monomer component may be heated to a temperature of 45 ° C. or higher, 50 ° C. or higher, 55 ° C. or higher, 60 ° C. or higher, or 65 ° C. or higher, and may be 80 ° C. or lower, 75 ° C. or lower, or 70 ° C. or lower. Can be heated.

Radical initiators are azo compounds or organic peroxides, specifically azobisisobutyronitrile, azobiscyanovaleric acid, 2,2'-azobis- (2,4-dimethyl) valeronitrile, dilaurolyl per It may include at least one of oxide, tertiary butyl peroxide, and diisopropyl peroxydicarbonate, but the kind thereof is not particularly limited, as long as it is a compound capable of forming monomer radicals of acrylonitrile, it is known Can be selected freely.

In addition, the radical initiator may be applied at a ratio of 0.1 to 1 relative to 1 mole of the compound of Formula 1. Specifically, the radical initiator may be applied in a ratio of 0.2 mol or more, or 0.4 mol or more, and may be applied in a ratio of 0.8 or less, or 0.6 mol or less, relative to 1 mol of the compound of Formula 1.

In addition, the monomer component may further include known additives required for polymerization reactions such as coupling agents, catalysts, antioxidants, stabilizers and the like.

The method according to the present application may further comprise stirring the monomer component. In addition, the stirring step may be stirred at a stirring speed of 100 rpm to 300 rpm using a known stirring equipment. Specifically, the stirring speed may be 120 rpm or more, or 140 rpm or more, and 250 rpm or less, 200 rpm or less, or 160 rpm or less.

Polymerizing the monomer component may be carried out while maintaining the temperature of the heated monomer component at a temperature of at least 45 ℃, at least 50 ℃, at least 55 ℃, at least 60 ℃, or at least 65 ℃, 80 ℃ or less, 75 ℃ or less Or, maintained at a temperature of 70 ° C. or less.

The step of polymerizing the monomer component may be carried out for a time in the range of 15 hours to 24 hours. Specifically, the polymerization time may be 17 hours or more, or 22 hours or less.

The conversion rate of the polyacrylonitrile prepared by the method according to the present application may be 70% or more. On the other hand, the upper limit of the conversion rate is not particularly limited, and may be, for example, less than 100%, 95% or less, 90% or less, 85% or less, or 80% or less. The conversion rate of a polymer may refer to the content of polymerized polymer as a percentage of the total content of monomers input for preparing the polymer, that is, the efficiency of polymerization. Therefore, polyacrylonitrile having a conversion rate in the above range may mean polymerized with high efficiency. In addition, in the present application, the conversion rate of polyacrylonitrile can be measured by the area ratio of the area corresponding to the portion converted to polyacrylonitrile through Nuclear Magnetic Resonance (NMR) analysis of polyacrylonitrile. have.

Another embodiment of the present application provides a polyacrylonitrile represented by the following Chemical Formula 2:

In formula (2), A is a unit of formula (3), X is a cyanoalkyl group, Z is a unit represented by formula (4), B is a unit of comonomer to acrylonitrile, a, b, c, d, e, f, g, h, i and j are each independently 0 or positive, b + d + g + i is positive and (a + b + c + d + e + f + g + h When + i + j) is converted to 1, b + d + g + i is a number greater than or equal to 0.8:

[Formula 3]

[Formula 4]

In formula (4), Y represents an oxygen atom, a sulfur atom, -S (= O) _2- , an alkylene group, an alkenylene group, an alkynylene group, an arylene group, -C (= O) -X _1- , or -X ₁ -C (= O)-, wherein X ₁ is a single bond, oxygen atom, sulfur atom, alkylene group, alkenylene group, alkynylene group, or arylene group, and * is at least one of A and B of formula (2) It is a site that binds with.

In formula (4), * binds to at least one of A and B in formula (2) means that A is bonded to both sides of Z of formula (2), or when B is bonded and A is bonded to one side and B to the other side It may mean that. For example, in Formula 2, when e is 0 and d and f are positive, * in Formula 4 may be a site that binds to A and B in Formula 2.

In Formula 4, Y may be the same as A in Formula 1. In addition, in Formula 4, Z and X may be a unit derived from Formula 1. The description of the cyanoalkyl group in the formula (2) may be the same as described above. X in Formula ₂ may be the same as Z ₁ and / or Z ₂ in Formula 1.

In the presence of the compound represented by Formula 1, when polymerizing a monomer component including acrylonitrile, both ends of the polyacrylonitrile are capped by the compound represented by Formula 1, which is represented by X and Z in Formula 2 above. appear. Specifically, X in Chemical Formula ₂ may mean Z ₁ and / or Z ₂ in Chemical Formula 1. In addition, in Formula 2, Z may refer to a unit in which Z ₁ and Z ₂ are separated from Formula 1, which may be represented by Formula 4. This is because the compound represented by the formula (1) is applied as a RAFT agent so that Z ₁ and / or Z ₂ of the formula (1) are reversibly added or fragmented to the polyacrylonitrile radical.

When the monomer component includes a comonomer for acrylonitrile, the polyacrylonitrile may include a polymerized unit (A) of acrylonitrile represented by Formula 3 and a polymerized unit (B) of comonomer, , A unit and B unit may be arranged in polyacrylonitrile regularly or irregularly. In the formula (2), because a, b, c, d, e, f, g, h, i and j are each independently 0 or positive. In Formula 2, when (a + b + c + d + e + f + g + h + i + j) is converted to 1, b + d + g + i is 0.80 or more, 0.85 or more, 0.90 or more, Or a number greater than or equal to 0.95, and less than 1, or less than or equal to 0.99.

In addition, the polyacrylonitrile may be prepared by the above production method.

The polyacrylonitrile may have a polydispersity index of 2 or less. Specifically, the polyacrylonitrile may have a polydispersity index of more than 1, 1.1 or more, 1.3 or more, 1.5 or more, or 1.7 or more, and may have a polydispersity index of 1.9 or less, 1.85 or less, or 1.83 or less. In the present application, the term polydispersity index may refer to the ratio of the weight average molecular weight (Mw / Mn) to the number average molecular weight of a certain polymer, and the closer to 1 the value, the more uniform the polymerization reaction means. can do.

In addition, the polyacrylonitrile may have a weight average molecular weight of 200,000 g / mol or more. Specifically, the polyacrylonitrile may be 220,000 g / mol or more, 240,000 g / mol or more, or 250,000 g / mol or more, 400,000 g / mol or less, 350,000 g / mol or less, 300,000 g / mol or less, or 260,000 or less than or equal to g / mol. Since the weight average molecular weight of a certain polymer contributes to the mechanical strength of the carbon fiber when the polymer is applied as a precursor to the carbon fiber manufacturing process, the carbon fiber made of polyacrylonitrile having the weight average molecular weight in the above range Sufficient strength can be secured. In the present application, the weight average molecular weight, the number average molecular weight, and the polydispersity index, as measured using gel permeation chromatography, may be expressed in terms of conversion to standard polymethylmethacrylate.

Within the range of polydispersity index, weight average molecular weight and conversion rate of the polyacrylonitrile, the polyacrylonitrile can be applied as a precursor of carbon fiber having no defects and excellent mechanical strength. In particular, when the polyacrylonitrile has a polydispersity index in the above-described range, there is an advantage suitable for the manufacturing process of the carbon fiber described below, specifically, the spinning process for producing a precursor of the carbon fiber. In addition, when the polyacrylonitrile has a weight average molecular weight in the above range, the mechanical properties of the carbon fiber produced therefrom is increased, a high strength carbon fiber can be produced.

Another embodiment of the present application provides a carbon fiber made of the polyacrylonitrile. That is, the polyacrylonitrile may be applied as a precursor of carbon fiber. As described above, since the polyacrylonitrile of the present application has a high weight average molecular weight and a narrow molecular weight distribution (polydispersity index), the carbon fiber may have excellent physical properties such as mechanical properties, chemical resistance, and heat resistance. Accordingly, the carbon fiber has an advantage that can be widely applied in various fields.

The method for producing the carbon fiber is not particularly limited, and a method for producing carbon fiber using polyacrylonitrile known in the art may be applied. For example, the carbon fibers may (1) form a polymer solution comprising polyacrylonitrile, (2) spin the polymer solution by wet spinning or dry spinning to form a carbon fiber precursor, and then (3) Oxidizing the carbon fiber precursor at a first temperature (eg, 200 ° C. to 300 ° C.), and then (4) carbonizing at a second temperature higher than the first temperature (eg, 1000 ° C. to 1500 ° C.). It can be prepared through. In addition, in the above process, the graphitization may be performed at a third temperature (for example, 2000 ° C. to 3000 ° C.) higher than the second temperature (5). In addition, a post-treatment process such as surface treatment may be additionally performed for convenience of processability.

The method for producing polyacrylonitrile according to the present application has high molecular weight and low polydispersity index, so that polyacrylonitrile suitable as a precursor of carbon fiber can be produced at high conversion rate.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples according to an exemplary embodiment of the present invention, but the scope of the present invention is not limited to the following examples.

1. NMR measurement

The conversion of acrylonitrile (AN) to polyacrylonitrile was measured under the following conditions using 1 H-NMR, and was calculated by the following Equation 1 according to the result.

<Measurement conditions>

Instrument: NMR, Varian Unity Inova 500 MHz

Solvent: DMSO-d6 (dimethyl sulfoxide-d6)

[Equation 1]

% Conversion = 100 X A / (A + B)

In Equation 1, A is the area of the peak (about 3.15 ppm) derived from PAN included in the polymer in the 1H-NMR spectrum, and B is the area of the peak (about 6.0 ppm) derived from unpolymerized AN.

2. Gel Permeation Chromatography (GPC)

The weight average molecular weight and polydispersity index (PDI) of polyacrylonitrile were measured using gel permeation chromatography. Polyacrylonitrile of Examples or Comparative Examples was added to a 2 mL vial, and diluted in DMF (dimethylformamide) containing LiBr at a concentration of 0.05 M to a concentration of about 4 mg / mL. Thereafter, the standard sample for calibration and the sample to be analyzed were filtered through a syringe filter (pore size: 0.45 μm) and measured. For analysis program, Empower2 of Waters was used, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were obtained by comparing the elution time of the sample with the calibration curve, and the molecular weight distribution (PDI) as the ratio (Mw / Mn) Was calculated. The measurement conditions of GPC are as follows.

Instrument: Alliance series by Waters

Column: Use 2 PL mixed B

Solvent: Dimethyl formamide (DMF) with 0.05 M LiBr

Column temperature: 60 ℃

Sample concentration: 4 mg / mL, 100 μL injection

Standard samples: polymethyl methacrylate (Mp: 1250000, 903000, 308000, 182000, 93300, 58700, 10000, 2580)

The structure of the chain transfer agent (RAFT agent) used in the examples and the comparative examples is as follows.

Chain transfer agent A-bis (2-cyano-2-propyl) 1,10-dekendyl bis (trithiocarbonate)

Chain transfer agent A was synthesized in the following order:

1) Under normal temperature conditions (about 25 ° C.), 1 equivalent of 1,10-dekeneddithiol and 2.6 equivalents of sodium hydride (NaH) are reacted with a diethylether solvent to give 2.2 equivalents of carbon disulfide (CS ₂ ). Reaction to give the result in the form of a salt.

2) The resultant obtained in 1) is reacted with 1.1 equivalents of iodine relative to the resultant using a diethylether solvent at room temperature to obtain the resultant.

3) The resultant obtained in 2) is reacted with an excess of azobisbutyronitrile (AIBN) at about 78 ° C. using ethyl acetate solvent to introduce cyanopropyl group to obtain chain transfer agent A.

Chain transfer agent B-bis (dodecylsulfanylthiocarbonyl) disulfide

As the chain transfer agent B, Sigma-Aldrich Co. No. 723126 was used.

Chain transfer agent C-2,21-dimethyl-4,19-dithioxo-3,5,18,20-tetracyadocosaidiioic acid

Chain transfer agent C was synthesized in the following order:

1) Mix 1 equivalent of 1,12-dodecanedithiol and 0.2 equivalent of tetrapropylammonium bromide with mild heating in an acetone / water mixed solvent and react with 2 equivalents of sodium hydroxide.

2) Reduce the temperature of the solution with cooling water (ice water) and react by adding 2 equivalents of CS ₂ .

3) A chain transfer agent C is obtained by reacting 2 equivalents of 2-bromo propanoic acid at room temperature.

Chain transfer agent D-2-cyano-2-propyl dodecyl trithiocarbonate

As chain transfer agent D, Zepu No. 723037 from Sigma-Aldrich was used.

Example 1 Synthesis of Polyacrylonitrile (A1)

Acrylonitrile monomer and itaconic acid monomer were placed in the reactor in a molar ratio of 98.70: 1.30, and about 80% by weight of dimethyl sulfoxide (DMSO) solvent relative to the total solution was added. Thereafter, the chain transfer agent A was added to the mixture in an amount of 0.05 mol% based on the total number of moles of the monomer to prepare a monomer component. The reactor containing the monomer component was purged with nitrogen and then heated to add azobisbutyronitrile (AIBN) as an initiator at a molar ratio of 0.5 to the mole number of chain transfer agent A at a temperature of about 67 ° C. Thereafter, a polyacrylonitrile (A1) was obtained by stirring at a temperature of about 67 ° C. and about 150 rpm for 20 hours using a stirrer.

Example 2 Synthesis of Polyacrylonitrile (A2)

Polyacrylonitrile (A2) was obtained in the same manner as in Example 1 except that 0.0666 mol% of Chain Transfer A was applied to the total number of monomers.

Comparative Example 1 Synthesis of Polyacrylonitrile (B)

Polyacrylonitrile (B) was obtained in the same manner as in Example 1, except that 0.05 mol% of the chain transfer agent D was applied based on the total number of monomers.

Comparative Example 2-Synthesis of Polyacrylonitrile (C)

Polyacrylonitrile (C) was obtained in the same manner as in Example 1 except that 0.0333 mol% of chain transfer agent D was applied based on the total number of monomers.

Comparative Example 3-Synthesis of Polyacrylonitrile (D)

Polyacrylonitrile (D) was obtained in the same manner as in Example 1, except that 0.02 mol% of chain transfer agent D was applied based on the total number of monomers.

Comparative Example 4-Synthesis of Polyacrylonitrile (E)

Polyacrylonitrile (E) was obtained in the same manner as in Example 1, except that 0.05 mol% of chain transfer agent B was applied to the total number of monomers.

Comparative Example 5-Synthesis of Polyacrylonitrile (F)

Polyacrylonitrile (F) was obtained in the same manner as in Example 1 except that 0.05 mol% of the chain transfer agent C was applied to the total number of monomers.

The physical property evaluation results of the polyacrylonitrile prepared according to Examples 1 to 2 and Comparative Examples 1 to 5 are shown in Table 1 below.

A1 A2 B C D E F Mn (kg / mol) 134 118 100 114 97 97 145 Mw (kg / mol) 250 207 158 177 144 164 332 PDI 1.80 1.74 1.58 1.55 1.48 1.69 2.29 % Conversion 71.8 75.3 71.2 46.5 27.5 49.4 72.8

According to Table 1, for the polyacrylonitrile (A1 and A2) according to Examples 1 and 2, which are polyacrylonitriles polymerized under the conditions according to the present application, a polydispersity index of 2 or less, weight of 200 kg / mol or more It can be seen that it is a suitable polyacrylonitrile, having an average molecular weight and made at a high conversion of at least 70%, and when used in the future production of carbon fibers. However, the polyacrylonitrile (B to F) according to Comparative Examples 1 to 5, which does not satisfy the conditions according to the present application, does not meet at least one of the polydispersity index, weight average molecular weight, and conversion rate conditions targeted by the present application. I can see that I can not.

Claims (14)

A method for producing a polyacrylonitrile comprising the step of polymerizing a monomer component comprising acrylonitrile in the presence of a compound represented by the formula (1):
[Formula 1]

In formula (1), A is an oxygen atom, a sulfur atom, -S (= O) _2- , an alkylene group, an alkenylene group, an alkynylene group, an arylene group, -C (= O) -X _1- , or -X ₁ -C (= O)-, wherein X ₁ is a single bond, oxygen atom, sulfur atom, alkylene group, alkenylene group, alkynylene group, or arylene group, Z ₁ and Z ₂ are each independently, It is a noalkyl group. The method for producing polyacrylonitrile according to claim 1, wherein A in Formula 1 is an alkylene group having 8 to 20 carbon atoms. The method for producing polyacrylonitrile according to claim 1, wherein Z ₁ and Z ₂ in Formula 1 each independently represent a cyanoalkyl group having a branched alkyl group having 1 to 8 carbon atoms. The process for producing polyacrylonitrile according to claim 1, wherein the monomer component comprises 80 mol% or more of acrylonitrile. The method of claim 1 wherein the monomer component further comprises a comonomer to acrylonitrile. The method of claim 1, wherein the compound of Formula 1 is present at a ratio of 0.2 mol or less relative to 100 mol of the total monomers of the monomer component. The process of claim 1 wherein the polymerization is carried out in the presence of a radical initiator. The method of claim 7, wherein the radical initiator is applied at a ratio of 0.1 to 1 based on 1 mole of the compound of Formula 1. 9. The process for producing polyacrylonitrile according to claim 1, wherein the polymerization is carried out in the absence of a surfactant. The process for producing polyacrylonitrile according to claim 1, wherein the conversion of acrylonitrile to polyacrylonitrile is 70% or more. Polyacrylonitrile represented by the following formula (2):
[Formula 2]

In formula (2), A is a unit of formula (3), X is a cyanoalkyl group, Z is a unit represented by formula (4), B is a unit of comonomer to acrylonitrile, a, b, c, d, e, f, g, h, i and j are each independently 0 or positive, b + d + g + i is positive and (a + b + c + d + e + f + g + h When + i + j) is converted to 1, b + d + g + i is a number greater than or equal to 0.8:
[Formula 3]

[Formula 4]

In formula (4), Y represents an oxygen atom, a sulfur atom, -S (= O) _2- , an alkylene group, an alkenylene group, an alkynylene group, an arylene group, -C (= O) -X _1- , or -X ₁ -C (= O)-, wherein X ₁ is a single bond, oxygen atom, sulfur atom, alkylene group, alkenylene group, alkynylene group, or arylene group, and * is at least one of A and B of formula (2) It is a site that binds with. 12. The polyacrylonitrile of claim 11 having a polydispersity index of 2 or less. 12. The polyacrylonitrile of claim 11 having a weight average molecular weight of at least 200,000 g / mol. Carbon fiber made of the polyacrylonitrile of claim 11.