JPH10110030A - Production of high-purity soluble aniline based conductive polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-purity soluble aniline based conductive polymer which reveals high conductivity and is excellent in solubility in water and organic solvents, and also excellent in applicability and film strength, by polymerizing a specified aniline substituted by acidic groups, or its salt in the presence of an oxidizing agent in a solution containing a basic compound. SOLUTION: At least one compound selected from among acidic group- substituted anilines, represented by formula 1 [wherein R1 , R2 , R3 , R4 and R5 are each H, a 1-4C alkyl, a 1-4C alkoxy, an acidic group, hydroxyl, etc., provided that at least one of them is an acidic group (wherein the acidic group designates a sulfo or carboxyl group)], and alkali (alkaline earth) metal salts, etc., thereof is polymerized in a mixture of an aqueous solution containing a basic compound with a water-soluble organic solvent by using an oxidizing agent, thus giving an objective polymer having mainly structural units of formula 2 (wherein R21 , R22 , R23 and R24 are the same as R1 to R5 in formula 1), with an Mw of at least 3,000 and a residual monomer content of at most 3wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a high-purity aniline-based conductive polymer that is soluble in water or an organic solvent. The polymer can form a conductor by a simple method such as a spray coating method, a dip coating method, a roll coating method, a gravure coating method, a reverse coating method, a roll brushing method, an air knife coating method, and a curtain coating method. . The composition containing the polymer as a main component includes various antistatic agents, capacitors, batteries, EMI shields, chemical sensors, display elements, non-linear materials, anticorrosion,
It can be applied to adhesives, fibers, antistatic paints, anticorrosive paints, electrodeposition paints, plating primers, bases for electrostatic painting, electrolytic protection, and improvement of battery storage capacity. Examples of applications of the antistatic agent include packaging materials, magnetic cards, magnetic tapes, magnetic disks, photographic films, printing materials, release films, heat seal tapes / film IC trays, IC carrier tapes, cover tapes, and the like. .

[0002]

2. Description of the Related Art Doped polyaniline (conductive polymer) is well known, but is insoluble in almost all solvents and has difficulty in molding and processing. Also, a method of subjecting aniline to electrolytic oxidative polymerization [JP-A-60-23585]
No. 1, J.I. Polymer Sci. Polyme
r Chem. Ed. , 26, 1531 (198
8)] can form a polyaniline film on the electrode, but has problems such as complicated isolation operation and difficulty in mass synthesis.

In recent years, alkali-soluble sulfonated polyanilines exhibiting conductivity without adding a dopant and a method for synthesizing the same, and carboxylated polyanilines and a method for synthesizing the same have been proposed.

As a method of synthesizing a sulfonated polyaniline, for example, a method of electrochemically polymerizing aniline and m-aminobenzenesulfonic acid to synthesize a sulfonated polyaniline (Journal of the Chemical Society of Japan, 1985, 1124, Japanese Patent Laid-Open No. No. 166165), a method of synthesizing a sulfonated polyaniline by electrochemically polymerizing o-, m-, and p-aminobenzenesulfonic acid alone [Preliminary Proceedings II of the 64th Annual Meeting of the Chemical Society of Japan II 706 ( 199
2)], a method of chemically polymerizing aniline and o-, m-aminobenzenesulfonic acid to synthesize a sulfonated polyaniline (Japanese Patent Application Laid-Open No. 01-301714), an aminobenzenesulfonic acid-based compound or aminobenzenesulfonic acid A method of chemically oxidatively polymerizing a monomer containing an aniline compound and an aniline compound (JP-A-6-56987);
A method of sulfonating an emeraldine-type polymer (polyaniline) obtained by chemically or electrochemically polymerizing with concentrated sulfuric acid (JP-A-58-210902). (JP-A-61-197633), a method of sulfonating with fuming sulfuric acid [J. Am. Chem. Soc. , (1
991) 113, 2665-2671; Am. Ch
em. Soc. , (1990) 112, 2800, WO
91-06887], a method of chemically polymerizing diphenylamine-4-sulfonic acid (sodium salt) to synthesize an N-substituted sulfonated polyaniline [Polymer,
(1993) 34, 158 to 162].

A method of synthesizing a sulfonated polyaniline by electrochemically polymerizing aniline and m-aminobenzenesulfonic acid (Journal of the Chemical Society of Japan, 1985, 1124, Japanese Patent Application Laid-Open No. 02-166165) discloses that a product is formed on an electrode. Therefore, there are problems that the isolation operation is complicated and mass synthesis is difficult.

[0006] In the Preprints II, 706 (1992) of the 64th Annual Meeting of the Chemical Society of Japan, a method for synthesizing a soluble conductive polymer by electrolytic oxidation of aminobenzenesulfonic acid is described. It is hard to say that it is suitable for mass synthesis. Further, it is described that no product was obtained when aminobenzenesulfonic acid was subjected to chemical oxidative polymerization using ammonium peroxodisulfate as an oxidizing agent. Also, J.I. Am. Chem. Soc. , (1991) 11
No. 3,265-2671 states that chemical and electrochemical polymerization of o-, m-aminobenzenesulfonic acid was unsuccessful.

In Japanese Patent Application Laid-Open No. 6-56987,
Aminobenzenesulfonic acid-based compound or a mixture of aminobenzenesulfonic acid-based compound and aniline-based compound can be used in any acidic, neutral or alkaline solution to obtain a water-soluble conductive polymer by chemical oxidation polymerization. There is a description, and an example of polymerization in a sulfuric acid solution is shown in Examples, but there is no description about the molecular weight of the polymer and other physical properties, and it is not clear what kind of physical properties of the polymer were obtained. According to the follow-up test of the present inventors, a polymer having a molecular weight sufficient to form a film could not be obtained.

Further, when the present inventors attempted polymerization in an aqueous solution containing a protonic acid and in an aqueous solution using ammonium peroxodisulfate as an oxidizing agent, a water-soluble polymer was obtained, but a low molecular weight polymer was obtained. Therefore, a practical polymer for forming a film could not be obtained.

A method of chemically polymerizing aniline and m-aminobenzenesulfonic acid with ammonium peroxodisulfate described in JP-A-01-301714 and an aniline and m-method described in JP-A-6-56987. The present inventors have further tested a method of chemically polymerizing aminobenzenesulfonic acid with potassium permanganate. As a result, only one sulfone group is introduced into five aromatic rings, and high conductivity is obtained. As shown, it was completely insoluble in neutral and acidic water, and almost insoluble in alkaline aqueous solutions such as ammonia. Also, JP-A-61-19
In the case of sulfonation according to the method of JP 7633,
As described on the page, the solubility of polyaniline in the sulfonating solvent is not sufficient and the reaction is carried out in a dispersed state, so that only one sulfone group is introduced into five aromatic rings. The thus obtained sulfonated polyaniline having a small sulfone group introduction ratio has a problem that conductivity and solubility are not sufficient.

Also, J. J. Am. Chem. Soc. ,
(1991) 113, 2665-2671; Am.
Chem. Soc. , (1990) 112, 2800, it is stated that when polyaniline is sulfonated with fuming sulfuric acid, about one sulfone group is introduced into two aromatic rings. However, when polyaniline is sufficiently sulfonated by the present method, a large excess of fuming sulfuric acid is required because the solubility of polyaniline in fuming sulfuric acid is not sufficient. Further, when polyaniline is added to fuming sulfuric acid, there is a problem that the polymer is easily solidified. Furthermore, the polymer synthesized by the above method and the sulfonated product thereof have a problem that they dissolve in an aqueous solution containing a base such as ammonia and alkylamine, but do not dissolve in water alone.

Also, Polymer (1993) 34,
According to 158 to 162, when diphenylamine-4-sulfonic acid (sodium salt) is polymerized, an N-substituted sulfonated polyaniline having one benzenesulfonic acid group introduced into the aniline skeleton is obtained, and water alone is used. Are dissolved, but the isolation of the polymer requires an ultracentrifugation operation. When the present inventors performed additional tests, the yield of the polymer obtained from the polymerization solvent was low due to high solubility, and the polymer could not be isolated without high-speed centrifugation. Was. In addition, because of the N-substitution type, J. Am. Chem. Soc. , (199
1) The conductivity was lower than that of the polymer synthesized by the method of 113, 2665 to 2671.

As a method for synthesizing carboxylated polyaniline, for example, a production method in which 2- or 3-carboxyaniline or a salt thereof is oxidatively polymerized and then treated with a basic substance to obtain a carboxyl group in a salt form ( JP 4
No. 268331), but the amount of the oxidizing agent to be used is twice or more the amount of the raw material, and the conductivity is low. From this, it is expected that a low-molecular-weight polymer is produced with low monomer reactivity.

[0013] Further, a synthesis method comprising polymerizing methyl anthranilate (methyl anthranilate) in an aqueous acidic medium in the presence of ammonium peroxodisulfate, and then saponifying the methyl ester with alcoholic potassium hydroxide (Japanese Patent Laid-Open No. 5-226238), but the operation is very complicated because the reaction has two steps.

Further, when the present inventors tried polymerization in an aqueous solution containing a protonic acid using ammonium peroxodisulfate as an oxidizing agent with 2-carboxyaniline, no product could be obtained. Further, the present inventors attempted polymerization in an aqueous solution containing a protonic acid using ammonium peroxodisulfate as an oxidizing agent using aniline and 2-carboxyaniline, and a copolymer was obtained. Both sexes were low. It is considered that the obtained copolymer has a low copolymerization ratio of 2-carboxyaniline.

Accordingly, it is necessary to introduce more acidic groups such as a sulfone group or a carboxyl group into the aromatic ring of the main chain in order to develop conductivity and improve solubility without adding a dopant to the polymer. It is thought that there is.

In consideration of formability such as film formation by coating, in order to be able to apply to both hydrophilic and hydrophobic substrates, it is necessary to have solubility in both water and an organic solvent. Is desired. However, polyaniline sulfonates have solubility in alkaline water, but are insoluble in neutral to acidic aqueous solutions, and are not sufficiently soluble in organic solvents.

As a method for solving these various problems,
The present inventors have copolymerized at least one compound selected from the group consisting of aniline, N-alkylaniline and phenylenediamine with aminobenzenesulfonic acid using an oxidizing agent in an acidic solvent, and further obtained a sulfonating agent. A method for producing a sulfonated aniline copolymer characterized by being sulfonated by a method described in JP-A-5-1789.
No. 89). However, this method also requires an operation of sulfonating in concentrated sulfuric acid, and treatment of waste acid remains as a major problem. In addition, it is presumed that each of the copolymers synthesized by the method has a structure represented by the following formula (4).

[0018]

Embedded image (Wherein, R _26, R _27, R ₂₈ and R ₂₉ are each a group selected from the group consisting of hydrogen and a sulfone group;
R ′ is a group selected from the group consisting of hydrogen and an alkyl group having 1 to 4 carbon atoms, and the proportion of the sulfone group is such that the content of the sulfone group is 40 to 80% with respect to the aromatic ring;
Represents an arbitrary number of 1 to 1, and n represents a degree of polymerization of 2 to 150.
Number of 0. )

Furthermore, the present inventors further studied aniline, N-
By copolymerizing at least one compound selected from the group consisting of alkyl anilines and phenylenediamines with an alkoxy-substituted aminobenzenesulfonic acid, an aniline-based copolymer that eliminates a sulfonation operation that generates a large amount of waste. Manufacturing method of coalescence (Japanese Patent Application No. 5-4854)
No. 0). Incidentally, it is presumed that each of the copolymers synthesized by the method has a structure represented by the following formula (5).

[0020]

Embedded image Wherein R _30, R _31, R _32, R _33, R _34, R _35, R ₃₆ and R ₃₇ are each a group selected from the group consisting of hydrogen, an alkoxy group and a sulfone group, Is that the sulfone group has a content of 25 to 50% based on the aromatic ring, the same aromatic ring contains an alkoxy group and a sulfone group, and R ^" is hydrogen or an alkyl group having 1 to 4 carbon atoms. A group selected from the group consisting of: x represents an arbitrary number of 0 to 1, and n is a number of 2 to 1500 indicating the degree of polymerization.)

Further, as the polymerization solvent in the chemical polymerization described above, water or an aqueous solution containing a protonic acid is used. For example, according to JP-A-1-163263, when ammonium peroxodisulfate is used as an oxidizing agent, it is particularly preferable to include a protonic acid having a pKa of 3 or less.
It is stated that those in which the protic acid and the oxidizing agent are dissolved and which are not oxidized by the oxidizing agent are used. In JP-A-4-268331, oxidative polymerization is carried out by adding an aqueous solution of ammonium persulfate to an aqueous solution of anthranilic acid, and the pH of the polymerization solvent is almost neutral.

[0022]

SUMMARY OF THE INVENTION The object of the present invention is to
A method for producing a high-purity soluble aniline-based conductive polymer that exhibits high conductivity, exhibits excellent solubility in water or an organic solvent having any pH, and has excellent coatability and film strength. It is in.

[0023]

Means for Solving the Problems The present inventors have developed a method for producing an acidic group-substituted polyaniline having a high ratio of introducing an acidic group such as a sulfone group and / or a carboxyl group to an aromatic ring as a polyaniline having high conductivity and solubility. As a result of intensive studies, it was found that aniline, such as sulfone-substituted aniline and / or carboxyl-substituted aniline, was polymerized using an oxidizing agent in a mixed solution of a basic compound-containing aqueous solution and an organic solvent mixed with water. Then, the reactivity was particularly improved, and it was found that high-molecular-weight polymers can be produced, contrary to the conventional belief that conventional anilines having a sulfone group or a carboxyl group are hardly chemically oxidized and polymerized by themselves. . The obtained polymer is further treated with an acid to further improve conductivity and solubility, and a composition containing these polymers as a main component has excellent coatability and remarkable film strength after coating. And found the present invention.

That is, the present invention provides a compound represented by the general formula (1):

Embedded image (Wherein R _1, R _2, R _3, R ₄ and R ₅ are each hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms) , A group selected from the group consisting of an acidic group, a hydroxyl group, a nitro group, and a halogen, at least one of which represents an acidic group, and the acidic group represents a sulfone group or a carboxyl group. At least one compound (a) selected from the group consisting of an acid group-substituted aniline, an alkali metal salt thereof, an alkaline earth metal salt, an ammonium salt and a substituted ammonium salt thereof is dissolved in an aqueous solution containing a basic compound (b) and water. Polymerization by an oxidizing agent in a mixed solution with a soluble organic solvent (c), represented by the following general formula (2)

Embedded image (Wherein, R _21, R _22, R ₂₃ and R ₂₄ are each hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, , A hydroxyl group, a nitro group and a halogen, at least one of which represents an acidic group, wherein the acidic group represents a sulfone group or a carboxyl group). The present invention relates to a method for producing a high-purity soluble aniline-based conductive polymer, characterized in that the polymer mainly has a weight average molecular weight of 3,000 or more and a residual monomer contained in the polymer of 3% by weight or less.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Typical examples represented by the general formula (1) are aniline substituted with a sulfone group or aniline substituted with a carboxyl group. The most typical sulfone-substituted anilines are aminobenzenesulfonic acids, specifically, o-, m-, p-aminobenzenesulfonic acid, aniline-2,6-disulfonic acid, and aniline-2,5. -Disulfonic acid, aniline-3,5-disulfonic acid, aniline-
2,4-Disulfonic acid and aniline-3,4-disulfonic acid are preferably used.

Other anilines substituted with a sulfone group include methylaminobenzenesulfonic acid, ethylaminobenzenesulfonic acid, n-propylaminobenzenesulfonic acid, iso-propylaminobenzenesulfonic acid, and n-propylaminobenzenesulfonic acid.
Alkyl group-substituted aminobenzenesulfonic acids such as -butylaminobenzenesulfonic acid, sec-butylaminobenzenesulfonic acid, t-butylaminobenzenesulfonic acid, methoxyaminobenzenesulfonic acid, ethoxyaminobenzenesulfonic acid, propoxyaminobenzenesulfonic acid, etc. Halogen-substituted aminobenzene sulfones such as alkoxy-substituted aminobenzenesulfonic acids, hydroxy-substituted aminobenzenesulfonic acids, nitro-substituted aminobenzenesulfonic acids, fluoroaminobenzenesulfonic acids, chloroaminobenzenesulfonic acids, and bromoaminobenzenesulfonic acids Acids and the like can be mentioned. Of these, alkyl-substituted aminobenzenesulfonic acids, hydroxy-substituted aminobenzenesulfonic acids, or halogen-substituted aminobenzenesulfonic acids are most practically preferable. In addition, these sulfone group-substituted anilines may be used alone or may be mixed in an isomer at an arbitrary ratio.

The most typical carboxyl group-substituted anilines are aminobenzenecarboxylic acids, specifically, o-, m-, p-aminobenzenecarboxylic acids,
Aniline-2,6-dicarboxylic acid, aniline-2,5-
Dicarboxylic acid, aniline-3,5-dicarboxylic acid, aniline-2,4-dicarboxylic acid, aniline-3,4-dicarboxylic acid and the like are preferably used.

Other carboxyl-substituted anilines include methylaminobenzenecarboxylic acid, ethylaminobenzenecarboxylic acid, n-propylaminobenzenecarboxylic acid, iso-propylaminobenzenecarboxylic acid,
Alkyl-substituted aminobenzenecarboxylic acids such as n-butylaminobenzenecarboxylic acid, sec-butylaminobenzenecarboxylic acid, t-butylaminobenzenecarboxylic acid, methoxyaminobenzenecarboxylic acid, ethoxyaminobenzenecarboxylic acid, propoxyaminobenzenecarboxylic acid Halogen-substituted aminobenzenes such as alkoxy-substituted aminobenzenecarboxylic acids, hydroxy-substituted aminobenzenecarboxylic acids, nitro-substituted aminobenzenecarboxylic acids, fluoroaminobenzenecarboxylic acids, chloroaminobenzenecarboxylic acids, bromoaminobenzenecarboxylic acids, etc. Examples thereof include carboxylic acids. Of these, alkyl-substituted aminobenzenecarboxylic acids, alkoxy-substituted aminobenzenecarboxylic acids, or halogen-substituted aminobenzenesulfonic acids are most practically preferable. These carboxyl group-substituted anilines may be used alone or may be mixed in an isomer at an arbitrary ratio.

The acidic group-substituted aniline represented by the general formula (1) is a sulfone group-substituted alkylaniline, a carboxyl group-substituted alkylaniline, a sulfone group-substituted alkoxyaniline, a carboxyl group-substituted alkoxyaniline, a sulfone group-substituted hydroxyaniline, or a carboxyl group-substituted aniline. Hydroxyaniline, sulfone-substituted nitroaniline, carboxyl-substituted nitroaniline, sulfone-substituted fluoroaniline, carboxyl-substituted fluoroaniline,
It can be expressed as any of sulfone group-substituted chloroaniline, carboxyl group-substituted chloroaniline, sulfone group-substituted bromoaniline, and carboxyl group-substituted bromoaniline. Table 1 shows specific examples of the positions and combinations of these substituents. .

[0030]

[Table 1] Here, A: one group selected from a sulfonic acid group or a carboxylic acid group, an alkali metal salt, an ammonium salt, and a substituted ammonium salt thereof; B: a methyl group, an ethyl group, an n-propyl group, an iso-propyl Groups, n-butyl group, sec-butyl group, t-butyl group and other alkyl groups, methoxy group, ethoxy group, n
One group selected from alkoxy groups such as -propoxy group, iso-propoxy group, n-butoxy group, sec-butoxy group, t-butoxy group, hydroxy group, fluoro group, chloro group, and bromo group; H: hydrogen, methyl group, ethyl group, n-propyl group, is
o-propyl group, n-butyl group, sec-butyl group,
t-butyl group, methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, sec
-Represents one group selected from an alkyl group such as a butoxy group, an alkoxy group, a hydroxy group, a nitro group, a halogen group such as a fluoro group, a chloro group, and a bromo group.

Examples of the alkali metal in these monomers include lithium, sodium, potassium and the like. Examples of the substituted ammonium include aliphatic ammonium, cyclic saturated ammonium, and cyclic unsaturated ammonium.

As the aliphatic ammoniums, the following formula (6)

Embedded image (Wherein R _{26 to} R ₂₉ are each independently selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, CH ₂ OH and CH ₂ CH ₂ OH).

Specifically, methyl ammonium, dimethyl ammonium, trimethyl ammonium, ethyl ammonium, diethyl ammonium, triethyl ammonium, methyl ethyl ammonium, diethyl methyl ammonium, dimethyl ethyl ammonium, propyl ammonium, dipropyl ammonium, isopropyl ammonium, diisopropyl ammonium , Butyl ammonium, dibutyl ammonium, methyl propyl ammonium, ethyl propyl ammonium, methyl isopropyl ammonium, ethyl isopropyl ammonium,
Methyl butyl ammonium, ethyl butyl ammonium, tetramethyl ammonium, tetramethylol ammonium, tetraethyl ammonium, tetra n-butyl ammonium, tetra sec-butyl ammonium,
Tetra-t-butylammonium and the like can be exemplified.

Examples of cyclic saturated ammoniums include piperidinium, pyrrolidinium, morpholinium, piperazinium, and derivatives having these skeletons.

The cyclic unsaturated ammoniums include pyridinium, α-picolinium, β-picolinium, γ-
Examples include picolinium, quinolinium, isoquinolinium, pyrrolium, and derivatives having these skeletons.

Next, as the basic compound (b) used in the present invention, ammonia, aliphatic amines, cyclic saturated amines, cyclic unsaturated amines and the like are preferably used. Above all, aliphatic amines, cyclic saturated amines, cyclic unsaturated amines and the like are preferable.

Preferred aliphatic amines include the following general formula (7)

Embedded image (Wherein, R _{30 to} R ₃₂ are an alkyl group having 1 to 3 carbon atoms, C
It is a group independently selected from the group consisting of H ₂ OH and CH ₂ CH ₂ OH. ),

Or the general formula (8)

Embedded image (Wherein, R _{33 to} R ₃₆ are each independently selected from the group consisting of hydrogen, an alkyl group having 1 to 3 carbon atoms, CH ₂ OH and CH ₂ CH ₂ OH.) Hydroxide compounds can be mentioned.

The cyclic saturated amines include piperidine,
Pyrrolidine, morpholine, piperazine, derivatives having these skeletons, and ammonium hydroxide compounds thereof are preferably used.

As the cyclic unsaturated amines, pyridine,
α-picoline, β-picoline, γ-picoline, quinoline, isoquinoline, pyrroline, derivatives having these skeletons, and ammonium hydroxide compounds thereof are preferably used.

Among these basic compounds, particularly preferred are methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylmethylamine, ethyldimethylamine, diethylmethylamine, pyridine, α-picoline,
β-picoline, γ-picoline and the like can be mentioned, and when these are used, a particularly high-purity polymer can be obtained.

The concentration of the basic compound (b) is 0.1.
It is used in an amount of 1 mol / L or more, preferably 0.1 to 10.0 mol / L, more preferably 0.2 to 8.0 mol / L. If it is less than 0.1 mol / l, the yield of the obtained polymer is reduced, and
If it is more than 0 mol / liter, the conductivity tends to decrease. The basic compound (b) may be used alone or in combination of two or more.

The weight ratio of the compound (a) such as the above-mentioned acid-substituted aniline to the basic compound (b) is (a):
(B) = 1: 100-100: 1, preferably 10: 9
0 to 90:10. Here, if the ratio of the basic compound is low, the reactivity tends to decrease and the conductivity tends to decrease. Conversely, when the ratio is high, the ratio of the salt formed between the acidic group and the basic compound in the obtained polymer increases, and the conductivity tends to decrease.

The molar ratio of the acidic group (e) to the basic compound (b) in the compound (a) such as the above-mentioned acid-substituted aniline is (e) :( b) = 1: 100 to 100: 1. , Preferably 1: 0.25 to 1:20, more preferably 1:
0.5 to 1:15. Here, if the ratio of the basic compound is low, the reactivity tends to decrease and the conductivity tends to decrease.
Conversely, when the ratio is high, the ratio of the salt formed between the acidic group and the basic compound in the obtained polymer increases, and the conductivity tends to decrease.

The polymerization or copolymerization is carried out by oxidative polymerization with an oxidizing agent in a mixed solution of the basic compound (b) -containing aqueous solution and an organic solvent (c) mixed with water. By using the mixed solution, the filterability of the polymer is remarkably improved, and the obtained polymer is highly purified. The organic solvent (c) is mixed with alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and water such as acetonitrile, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and dimethylsulfoxide. Organic solvents are preferably used. In particular, methanol,
Preferred are ethanol, isopropanol, acetone, acetonitrile, dimethylformamide, dimethylsulfoxide and the like. These organic solvents can be used alone or as a mixture, or as a mixture with water.

The mixing ratio (weight ratio) of water and the organic solvent is water: organic solvent (c) = 5: 95 to 95: 5, preferably 10:90 to 90:10, and more preferably 2:95.
0:80 to 80:20.

The oxidizing agent has a standard electrode potential of 0.6 V
The oxidizing agent is not particularly limited as long as it is the above oxidizing agent, but peroxodisulfuric acids such as peroxodisulfuric acid, ammonium peroxodisulfate, sodium peroxodisulfate, and potassium peroxodisulfate, hydrogen peroxide, and the like are preferably used. It is used in an amount of 0.1 to 5 mol, preferably 0.5 to 5 mol. At this time, it is also effective to add a transition metal compound such as iron or copper as a catalyst.

The reaction temperature applied in the present invention is from -15 to
The temperature range is 70 ° C, preferably -10 to 60 ° C, more preferably -5 to 40 ° C. Temperature is -15 ° C
If the temperature is lower than 70 ° C., the polymerization is not sufficient.

The hydrogen at the sulfone or carboxyl group in the polymer produced according to the invention may be hydrogen,
It is a group independently selected from the group consisting of alkali metals, ammonium and substituted ammonium, that is, these groups can be obtained not only alone but also in a mixed state.

Specifically, when polymerized in the presence of sodium hydroxide, most of the hydrogen in the sulfone group or carboxyl group in the isolated polymer has been replaced with sodium.

Similarly, the hydrogen in the sulfone group or the carboxyl group in the polymer is mostly ammonium when polymerized in the presence of ammonia, and is mostly trimethylammonium in the case of polymerization in the presence of trimethylamine, in the presence of quinoline. When polymerized, it is mostly obtained with quinolinium.

When a mixture of basic compounds is used, it is obtained in a state of mixing these. Specifically, when polymerized in the presence of sodium hydroxide and ammonia, hydrogen at the sulfone or carboxyl groups in the isolated polymer is obtained in the presence of both sodium and ammonium. Similarly, when the obtained polymer is treated with a solution in which both sodium hydroxide and ammonia are present, hydrogen in the sulfone group or carboxyl group in the polymer is obtained in a state where both sodium and ammonium are present.

The above-mentioned polymer in which a part of the acidic group forms a salt can be treated with an acid-containing solution to obtain a higher-purity polymer.

Examples of the acid include mineral acids such as hydrochloric acid, nitric acid, sulfuric acid, and borofluoric acid; superacids such as trifluoromethanesulfonic acid; and alkyls such as methanesulfonic acid, dodecylbenzenesulfonic acid, toluenesulfonic acid, and camphorsulfonic acid. Examples include group-substituted sulfonic acids, and preferably, hydrochloric acid, nitric acid, sulfuric acid, p-toluenesulfonic acid and the like are used. These solvents are not particularly limited as long as they are mixed with these protonic acids, but alcohols such as methyl alcohol, ethyl alcohol, iso-propyl alcohol, n-propyl alcohol, t-butyl alcohol, acetone, methyl ethyl ketone , Ketones such as methyl isobutyl ketone, glycols, glycol ethers, acetonitrile, N, N-dimethylformamide,
N-methylpyrrolidone, dimethylsulfoxide and the like are preferably used, and methyl alcohol, ethyl alcohol, iso-propyl alcohol, acetone and acetonitrile are particularly preferable. As the concentration of the acid used here,
0.1 to 10 mol / l, preferably 0.1 to 5 mol / l is effective.

The polymer is isolated by filtration from the reaction solution, but unreacted monomers are dissolved in the reaction solution.
At this time, as a separation device, vacuum filtration, pressure filtration,
Centrifugation, centrifugal filtration, etc. are used, especially centrifugation,
It is preferable to use a separation device such as centrifugal filtration. At the time of separation, if the temperature of the reaction solution is 5 ° C. or higher, separation of by-products is improved, and a high-purity polymer can be obtained. The temperature range is 5 to 80C, preferably 10 to 70C, more preferably 15 to 60C.

As washing solvents, alcohols such as methyl alcohol, ethyl alcohol, iso-propyl alcohol, n-propyl alcohol, t-butyl alcohol, acetone, acetonitrile, N, N-dimethylformamide, N-methyl Pyrrolidone, dimethyl sulfoxide and the like are used, and it is particularly effective to use methyl alcohol, ethyl alcohol, iso-propyl alcohol, acetone and acetonitrile.

According to the above method, the following general formula (2)

Embedded image (Wherein, R _21, R _22, R ₂₃ and R ₂₄ are each hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, , A hydroxyl group, a nitro group and a halogen, at least one of which represents an acidic group, wherein the acidic group represents a sulfone group or a carboxyl group). And a soluble aniline-based conductive polymer having a weight average molecular weight of 3,000 or more. The purity of the polymer is such that the residual monomer is 3
5% by weight or less, 5% by weight or less of oligomers having an average weight molecular weight of 1100 or less, and 3% by weight of residual salts, acids and bases
% Or less, preferably 2 wt% or less of residual monomers, 3 wt% or less of oligomers having an average weight molecular weight of 1100 or less, 2 wt% or less of residual salts, acids, and bases, more preferably 0.5 wt% or less of residual monomers, Oligomer having an average weight molecular weight of 1100 or less is 1 wt% or less,
Residual salts, acids and bases are each 1 wt% or less, particularly preferably 0.5 wt% or less of residual monomers, 0.5 wt% or less of oligomers having an average weight molecular weight of 1100 or less, and 0 or less of residual salts, acids and bases. It is of high purity of not more than 0.5 wt%. The higher the purity, the better the conductivity and solubility.

The weight average molecular weight of this polymer is 3
000-3,240,000, preferably 5,000-
1,000,000, more preferably 10,000 to
500,000.

This polymer is subjected to a water or a base containing ammonia, an alkylamine or the like, a base such as ammonium acetate or ammonium oxalate or a basic salt, an acid such as hydrochloric acid, sulfuric acid or the like without further sulfonation. , Methyl alcohol, ethyl alcohol, isopropyl alcohol, and the like, or a mixture thereof.

The polymer obtained by this method is
It can be expressed as having a phenylenediamine structure (reduced type) and a quinodiimine structure (oxidized type) represented by the following general formula (3).

Embedded image (Wherein, R _{25 to} R ₄₀ represent an electron-withdrawing group, an acidic group, hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms,
4, a group selected from the group consisting of linear or branched alkoxy, hydroxyl, nitro, and halogen;
At least one of them represents an acidic group. Here, the acidic group indicates a sulfone group or a carboxyl group. Of these, at least two of the four substituents on each aromatic ring are each preferably a combination of an acidic group and an alkyl group, a hydroxyl group, a halogen group or an alkoxy group, and particularly preferably a combination of an acidic group and an alkoxy group.

The phenylenediamine structure (reduced form) and the quinodiimine structure (oxidized form) can be reversibly converted at any ratio by oxidation or reduction. The ratio of the phenylenediamine structure to the quinodiimine structure is 0.2 <
The range of x <0.8 is preferable from the viewpoint of conductivity and solubility, and the range of 0.3 <x <0.7 is more preferable. The ratio is small when oxidized with an oxidizing agent such as benzoyl peroxide, ammonium peroxodisulfate, and hydrogen peroxide, but reduced when reduced with a reducing agent such as hydrazine, phenylhydrazine, sodium borohydride, and sodium hydride. Big things are obtained.

The high-purity soluble aniline-based conductive polymer of the present invention, as a structural unit other than those represented by the above general formula (1) or (2), has an effect on solubility, conductivity and properties. As long as it is not present, it may contain at least one structural unit selected from substituted or unsubstituted aniline, thiophene, pyrrole, phenylene and vinylene.

In this case, the content of the acidic group to the repeating unit of the general formula (1) or the general formula (2), that is, the aromatic ring is 70% or more, preferably 80% or more.
More preferably, it must be contained at 90% or more. If the content is less than 70%, the solubility in water is insufficient, so that it is not preferred. The higher the content of the acidic group with respect to the aromatic ring, the better the solubility in water, and the one with a content of the acidic group of 100% has the highest solubility.

[0064]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[Measurement Method] The IR spectrum was measured using an apparatus manufactured by PerkinElmer (model 1600). For the measurement of the molecular weight distribution and the molecular weight, GPC measurement (in terms of polyethylene glycol) was performed using a GPC column for an aqueous solution. The column was used by connecting three types of gel filtration chromatography columns for aqueous solution. In addition, a 0.2 M phosphate buffer solution was used as an eluent. Analysis of the acid group-substituted aniline, residual salt, and acid in the polymer was performed using ion chromatography. The column used was an anion column, and the eluent used was 1 mmol / l acetate buffer. The conductivity is
The conductivity was measured by a four-terminal method, and the surface resistance was measured by a two-terminal method. The pencil test method was used for the film strength.

Example 1 100 mmol of o-aminobenzenesulfonic acid was added at 25 ° C.
The solution was stirred and dissolved in a 4 mol / l trimethylamine solution (acetonitrile / water = 1/1; weight ratio), and a solution of 100 mmol of ammonium peroxodisulfate (acetonitrile / water = 1/1; weight ratio) was added dropwise. After dropping, 2
After further stirring at 5 ° C. for 12 hours, the reaction product was separated by filtration with a centrifugal filter, washed with methyl alcohol and dried to obtain 15 g of a polymer powder. This had a volume resistance of 12.0 Ωcm. The residual monomer contained in this polymer, o-aminobenzenesulfonic acid, was 1%, and trimethylamine sulfate, a by-product salt, was 1%.

3 parts by weight of the above polymer was stirred and dissolved in 100 parts by weight of water at room temperature to prepare a conductive composition. The solution thus obtained was applied on a glass substrate by a spin coating method, and dried at 100 ° C. A film having a thickness of 0.1 μm and a smooth surface resistance value of 1.0 × 10 ⁵ Ω / □ was obtained.

As a result of GPC measurement, the molecular weight of this product was found to be number average molecular weight (Mn) 15,000 and weight average molecular weight (M
w) 19,000, Z-average molecular weight (Mz) 21,00
0, the degree of dispersion Mw / Mn = 1.3, and Mz / Mw = 1.1.

The polymer was added little by little to 10 ml of water, 0.1 mol / l sulfuric acid aqueous solution or 0.1 mol / l aqueous ammonia, and filtered when it was no longer dissolved. The solubility of the polymer was water 350 mg / ml 0.1 mol / l aqueous sulfuric acid solution 295 mg / ml 0.1 mol / l aqueous ammonia 400 mg / ml.

FIG. 1 shows the IR spectrum of the polymer, FIG. 2 shows the ion chromatography of the residual monomer and residual by-product salt in the polymer, and FIG. 2 shows the high-performance liquid chromatography of the residual monomer and basic compound in the polymer. FIG. 3 shows the graph, and FIG. 4 shows a chart of the GPC measurement in the polymer. The assignment of the IR spectrum is as follows. Sulfone group: absorption around 1120, 1020 cm | Polymer skeleton: absorption around 1500 cm |

Example 2 100 mmol of 2-aminoanisole-4-sulfonic acid
Was dissolved in a 4 mol / l triethylamine solution (acetone / water = 1/1; weight ratio) at 5 ° C., and a 100 mmol solution of ammonium peroxodisulfate (acetone / water = 1/1) was dissolved.
(1; weight ratio) while cooling. After completion of the dropwise addition, the mixture was further stirred at 20 ° C. for 12 hours, then the reaction product was separated by a centrifugal filter, washed with ethyl alcohol and dried to obtain about 18 g of a polymer powder. This had a volume resistivity of 10.0 Ω · cm. The residual monomer contained in this polymer, 2-aminoanisole-4-sulfonic acid, was 0.5%, and triethylamine sulfate, a by-product salt, was 0.4%.

A conductive composition was prepared by dissolving 5 parts by weight of the polymer in 100 parts by weight of a 0.2 mol / l sulfuric acid aqueous solution at room temperature with stirring. The solution thus obtained was applied on a glass substrate by a spin coating method, and dried at 100 ° C. Film pressure 0.2 μm, smooth surface resistance 1.0 ×
A film of 10 ⁵ Ω / □ was obtained.

Example 3 100 mmol of 2-aminophenol-4-sulfonic acid
Was dissolved at 5 ° C. in a 3 mol / l methylpyridine solution (acetonitrile / water = 3/7; weight ratio), and a 100 mmol solution of ammonium peroxodisulfate (acetone / water =
(3/7; weight ratio) was added dropwise while cooling. After completion of the dropwise addition, the mixture was further stirred at 20 ° C for 12 hours, and then the polymerization solution was heated to 40 ° C. After heating, the mixture was further stirred at 40 ° C. for 2 hours, and the reaction product was separated by a centrifugal filter, washed with methyl alcohol and dried to obtain about 15 g of a polymer powder. Its volume resistance is 8.
It was 0 Ω · cm. Further, 2-aminoanisole-4-sulfonic acid as a residual monomer contained in this polymer was 0.1%, and methylpyridine sulfate as a by-product salt was 0.1%.

3 parts by weight of the above polymer was stirred and dissolved in 100 parts by weight of water at room temperature to prepare a conductive composition. The solution thus obtained was applied on a PET film by a spin coating method, and dried at 120 ° C. A film having a smooth surface resistance of 1.0 × 10 ⁵ Ω / □ on the surface having a thickness of 1 μm was obtained.

Example 4 100 mmol of 2-aminophenol-4-sulfonic acid
Was dissolved at 10 ° C. in a 3 mol / l pyridine solution (N, N-dimethylformamide / water = 7/3; weight ratio), and a 100 mmol ammonium peroxodisulfate solution (N, N
(N-dimethylformamide / water = 7/3; weight ratio) was added dropwise while cooling to -5 to 30 ° C. After completion of the dropwise addition, the mixture was further stirred at 20 ° C. for 12 hours, and then the reaction product was separated by filtration, then washed with acetone and dried to obtain about 20 g of a polymer powder. Its volume resistance is 12.0Ω
cm. The residual monomer contained in the polymer, 2-aminoanisole-4-sulfonic acid, was 1.0%, and methylpyridine sulfate, a by-product salt, was 1.0%.
%Met.

3 parts by weight of the polymer was stirred and dissolved at room temperature in 100 parts by weight of a solution of isopropyl alcohol / water = 5/5 (weight ratio) to prepare a conductive composition. The solution thus obtained was applied on a quartz substrate by spin coating, and dried at 120 ° C. A film having a smooth surface resistance of 4.0 × 10 ⁵ Ω / □ on the surface having a thickness of 0.1 μm was obtained.

Example 5 2-methyl-4-aminobenzenesulfonic acid 100 mm
was dissolved in a 4 mol / l trimethylamine solution (isopropylamine / water = 1/1; weight ratio) at 5 ° C. while cooling a 100 mmol ammonium peroxodisulfate solution (isopropylamine / water = 1/1; weight ratio). It was added dropwise so as to reach 0 to 10 ° C. After dropping, 20 ° C
After further stirring for 12 hours, the polymerization solution was heated to 40 ° C. After heating, the mixture was further stirred at 40 ° C. for 2 hours, then the reaction product was separated by filtration, washed with isopropyl alcohol and dried to obtain about 14 g of a polymer powder. This had a volume resistivity of 10.0 Ω · cm. The residual monomer contained in this polymer, 2-methyl-4-aminobenzenesulfonic acid, was 0.6%, and trimethylamine sulfate, a by-product salt, was 0.5%.

3 parts by weight of the above polymer and a water-soluble polyester resin "Alastar 300" (Arakawa Chemical Industry Co., Ltd.)
00 parts by weight were stirred and dissolved at room temperature in 100 parts by weight of water to prepare a conductive composition. The solution thus obtained is treated with PE
Dip coating method on T film, 120
Dry at ℃. A film having a film thickness of 1 μm and a smooth surface resistance value of 3.0 × 10 ⁵ Ω / □ was obtained.

Example 6 100 mmol of o-aminobenzenesulfonic acid was added at 25 ° C.
And dissolved in a 3 mol / l trimethylamine solution (DMSO / water = 3/7; weight ratio) with a solution of 100 mmol of ammonium peroxodisulfate (DMSO / water = 3 /
7; by weight) was added dropwise while cooling to -5 to 30 ° C. After completion of the dropwise addition, the mixture was further stirred at 20 ° C. for 12 hours, and the reaction product was separated by a centrifugal filter and dried to obtain 15 g of a polymer powder. This had a volume resistivity of 20.0 Ωcm. The residual monomer contained in the polymer, o-aminobenzenesulfonic acid, was 1.0%, and trimethylamine sulfate, a by-product salt, was 1.%.
2%.

5 parts by weight of the above polymer was stirred and dissolved in 100 parts by weight of water at room temperature to prepare a conductive composition. The solution thus obtained was applied on a PET film by a dip coating method, and dried at 120 ° C. A film having a thickness of 1 μm and a smooth surface resistance of 8.0 × 10 ⁵ Ω / □ was obtained.

Comparative Example 1 2-aminoanisole-4-sulfonic acid 100 mmol
Is dissolved at 10 ° C. in a 3 mol / l aqueous piperidine solution,
A 100 mmol aqueous solution of ammonium peroxodisulfate was added dropwise while cooling to 15 to 30 ° C. After the dropwise addition, the mixture was further stirred at 20 ° C. for 12 hours, and then the reaction product was washed with acetonitrile and dried, and about 8 g of polymer powder was obtained.
I got This had a volume resistance value of 55.0 Ω · cm. The residual monomer contained in this polymer, 2-aminoanisole-4-sulfonic acid, was 5%, and piperidine sulfate, a by-product salt, was 9%.

3 parts by weight of the above polymer was stirred and dissolved in 100 parts by weight of water at room temperature to prepare a conductive composition. The solution thus obtained was applied on a glass substrate by a spin coating method, but the coatability was poor and a uniform film could not be formed.

Comparative Example 2 100 mmol of o-aminobenzenesulfonic acid was added at 25 ° C.
Then, a solution of 100 mmol of ammonium peroxodisulfate (DMSO / water = 3/7; weight ratio) was added dropwise while cooling to a temperature of -5 to 30 ° C. After dropping, 20
After further stirring at 12 ° C. for 12 hours, the reaction product was separated by a centrifugal filter and dried to obtain 7 g of a polymer powder. This had a volume resistivity of 150.0 Ωcm. The residual monomer contained in this polymer, o-aminobenzenesulfonic acid, was 8.0%, and trimethylamine sulfate, a by-product salt, was 11%.

5 parts by weight of the polymer was stirred and dissolved in 100 parts by weight of water at room temperature to prepare a conductive composition. The solution thus obtained was applied on a PET film by a dip coating method, but the coatability was poor and a uniform film could not be formed.

Comparative Example 3 100 mmol of 2-aminophenol-4-sulfonic acid
Was dissolved in a 3 mol / l aqueous solution of triethylamine at 10 ° C, and a 100 mmol solution of ammonium peroxodisulfate was added dropwise while cooling to 5 to 20 ° C. After completion of the dropwise addition, the mixture was further stirred at 20 ° C. for 12 hours, then the reaction product was separated by a centrifugal filter, washed with acetonitrile, and dried to obtain about 12 g of a polymer powder. This had a volume resistance of 35.0 Ω · cm. The residual monomer contained in this polymer, 2-aminophenol-4-sulfonic acid, was 4%, and piperidine sulfate, a by-product salt, was 5%.

3 parts by weight of the above polymer was dissolved in 100 parts by weight of water at room temperature with stirring to prepare a conductive composition. The solution thus obtained was applied on a PET film by a dip coating method, and dried at 150 ° C. A film having a thickness of 1 μm and a smooth surface resistance value of 8.0 × 10 ⁶ Ω / □ was obtained. However, the obtained film had crystals precipitated on the surface and was not smooth.

[0087]

According to the present invention, high conductivity is exhibited, and at the same time, excellent solubility in aqueous solutions having all pHs of alkaline, neutral (particularly simple water) and acidic, and organic solvents such as acetonitrile and alcohol. Thus, it was possible to provide a method for producing a high-purity soluble conductive polymer having excellent coatability and film strength.

[Brief description of the drawings]

FIG. 1 is an IR chart in a polymer in Example 1.

FIG. 2 is a chart of ion chromatography of residual monomers and residual by-product salts in a polymer in Example 1.

FIG. 3 is a high-performance liquid chromatography chart of residual monomers and basic compounds in a polymer in Example 1.

FIG. 4 is a GPC chart of a polymer in Example 1.

Claims (9)

[Claims] 1. A compound of the general formula (1) (Wherein R _1, R _2, R _3, R ₄ and R ₅ are each hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms) , A group selected from the group consisting of an acidic group, a hydroxyl group, a nitro group, and a halogen, at least one of which represents an acidic group, and the acidic group represents a sulfone group or a carboxyl group. At least one compound (a) selected from the group consisting of an acid group-substituted aniline, an alkali metal salt thereof, an alkaline earth metal salt, an ammonium salt and a substituted ammonium salt thereof is dissolved in an aqueous solution containing a basic compound (b) and water. The polymerization is carried out with an oxidizing agent in a mixed solution with a soluble organic solvent (c). (Wherein, R _21, R _22, R ₂₃ and R ₂₄ are each hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an acidic group, , A hydroxyl group, a nitro group and a halogen, at least one of which represents an acidic group, wherein the acidic group represents a sulfone group or a carboxyl group). A method for producing a high-purity soluble aniline-based conductive polymer, characterized in that the polymer mainly has a weight average molecular weight of 3000 or more and a residual monomer content of 3% by weight or less. 2. The structural formula of the soluble aniline-based conductive polymer is represented by the following general formula (3). (Wherein, R _{25 to} R ₄₀ represent an electron-withdrawing group, an acidic group, hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms,
4, a group selected from the group consisting of linear or branched alkoxy, hydroxyl, nitro, and halogen;
At least one of them represents an acidic group. The method for producing a high-purity soluble aniline-based conductive polymer according to claim 1, wherein the acidic group has a repeating unit represented by a sulfone group or a carboxyl group. 3. The method for producing a high-purity soluble aniline-based conductive polymer according to claim 1, wherein the basic compound (b) is an alkylamine having 1 to 3 carbon atoms and / or a heterocyclic amine. 4. The high-purity soluble solvent according to claim 1, wherein the organic solvent is at least one selected from the group consisting of alcohols, ketones, acetonitrile, dimethylformamide and dimethylsulfoxide. A method for producing an aniline-based conductive polymer. 5. The method for producing a high-purity soluble aniline-based conductive polymer according to claim 1, wherein after the polymerization, the polymer is subjected to an acid treatment with a solution (d) containing a protonic acid. 6. The process for producing a high-purity soluble aniline-based conductive polymer according to claim 1, wherein the oxidative polymerization is carried out at a temperature of 50 ° C. or lower. 7. The method according to claim 1, wherein after the polymerization, the polymer or the polymer after the acid treatment is washed with at least one solvent selected from methanol, ethanol, isopropyl alcohol, acetone, acetonitrile and N, N-dimethylformamide. 7. The method for producing a high-purity soluble aniline-based conductive polymer according to 1, 2, 3, 4, 5, or 6. 8. The method according to claim 1, wherein after the polymerization, the polymer or the acid-treated polymer is isolated using a separation device utilizing centrifugal force. A method for producing a high-purity soluble aniline-based conductive polymer. 9. The method for producing a high-purity soluble aniline-based conductive polymer according to claim 8, wherein the temperature of the polymerization solution is 10 ° C. or less when the polymer is isolated using a separation device utilizing centrifugal force.