JP2001288264A - Method for producing polyaniline-containing solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved method for producing a solution containing a conductive polyaniline. SOLUTION: This method comprises the steps of: forming an emulsion by mixing an aniline monomer, a water-inmiscible organic solvent, at least one protonic acid dopant, and water together; stopping the agitation to separate the emulsion into an aqueous phase and a nonaqueous phase; separating the nonaqueous phase from the aqueous phase; and polymerizing the aniline monomer after adding an oxidizing agent to the nonaqueous phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyaniline-containing solution, and more particularly to a method for producing an optionally transparent polyaniline-containing solution formed in situ during the polymerization of an aniline monomer.

[0002]

BACKGROUND OF THE INVENTION Conductive coatings are widely used in antistatic electrostatic dischargers, electromagnetic interference (EMI) shields, and insulating plastic materials.

[0003] One type of conductive paint is called conductive p.
aint) is manufactured by mixing a resin with a powdered metal such as Zn, Ni or Ag. However, this type of conductive coating has several disadvantages. First,
Due to the high density of the metal powder in the conductive paint, the metal powder tends to sink to the bottom of the conductive paint every time the paint is insufficiently stirred or completely stopped. In order to keep the paint concentration uniform, it is necessary to stir the conductive paint throughout the coating. Secondly, when the coating layer of the conductive paint is dried in the open air, the metal powder particles in the conductive paint gradually precipitate and coalesce together to gradually deteriorate the quality. Third, when the paint is exposed to air, the powdered metal is susceptible to oxidation, resulting in long-term electrical-insulation. Finally, powdered metals in conductive coatings are costly and can be detrimental to the environment as debris in the plastics in which they are mixed or coated with them.

[0004] Polyaniline is one of the promising conductive polymers that can be used in a variety of applications such as paint, insulation protection, electromagnetic protection, electro-optical devices such as liquid crystal devices (LCDs) and photovoltaic cells, converters, circuit boards, and the like. It has become clear that it is one. However, since polyaniline is insoluble in common solvents, there have been many problems in processing to the above useful products.

[0005] Generally, polyaniline is prepared from hydrochloric acid or H2SO4.
Is produced as a salt of emeraldine (dark green dye) by chemically oxidative polymerization in the presence of a protonic acid such as The solid emeraldine salt usually precipitates in the reaction mixture during the polymerization. Therefore, to obtain solid polyaniline for use in each of the above applications, the solid salt must be recovered from the reaction mixture, filtered, washed with water and a solvent, and dried. The usually insoluble nature of the polyaniline so obtained has hindered the application of polyaniline.

[0006] PCT US 92 Patent No. 04167 discloses the use of functionalized protonic acids in the production of conductive polyaniline to increase the processability and solubility of the conductive polyaniline in organic solvents. ing.

Harlev et al. (US Pat. No. 5,618,469) are directed to use in the manufacture of conductive and possibly transparent coatings, and to liquid crystal and other electro-optical devices.
A method for producing a processable solution of emeraldine salt is disclosed. Such a method involves oxidatively polymerizing an aniline monomer in the presence of a protonic acid such as pyruvic acid to obtain a solid emeraldine salt, reacting the solid emeraldine salt with an aqueous ammonia solution to obtain a solid emeraldine base, Is further dissolved in an additional amount of pyruvic acid to form a polyaniline solution.

A disadvantage of the above process is that the salt of emeraldine formed in the reaction mixture during the oxidative polymerization precipitates insolublely, so that the precipitated salt is converted into solid emeraldine base which is then converted to pyrvin Complex steps may be required to dissolve in the acid to form a processable polyaniline solution.

Smith et al. (US Patent No. 5,470,505)
Is a salt of emeraldine, prepared by a standard method of oxidatively polymerizing an aniline monomer in the presence of a protonic acid, is an acid,
Especially rich H2SO4, CH3SO3H, CISO3
H, CF3SO3H and HNO3 (70% fuming concentrated nitric acid)
Which can be dissolved in a strong acid such as The salt of emeraldine (polyaniline) dissolved in one of these acid solutions is then processed into suitable articles for application.

Abe et al. (US Patent No. 5,728,321)
Dopant (do in oxidative polymerization of aniline monomer
pant) as a doped state by a method using a special protonic acid such as hydrofluoroboric acid, perchloric acid, or any other organic acid having an acid dissociation constant pKa of 4.8 or less. (Dissolved in an aprotic polar solvent such as N-methyl-2-pyrrolidone).
Further, the polyaniline insoluble in the organic solvent obtained by the above method can be dissolved in the aprotic solvent in a state that does not contain any inclusions (undoped). Undoping for making the doped polyaniline soluble in an organic solvent is troublesome and has a problem of increasing the production cost.

[0011]

The traditional process for producing polyaniline in a processable form, including the process described above, is to obtain solid polyaniline due to the insolubility of the polyaniline formed in the reaction mixture. In order to do so, it is necessary to recover, filter, wash and dry the reaction products,
Further, there is a problem that an additional step of converting a salt of emeraldine into a base of emeraldine and dissolving solid polyaniline or the base of emeraldine in a solvent is necessary in order to obtain a desired polyaniline solution.

[0012]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a processable solution of polyaniline which is doped with an acid prepared by oxidative polymerization of aniline monomers. The present invention provides a method for producing a solution in which the obtained (acid-containing) polyaniline is sufficiently dissolved in the non-aqueous phase in the mixture of the polymerization reaction.

According to the above method, the use of an additional solvent for dissolving the polyaniline and / or the undoping or redopeing of the solid polymerization product is not required. The method provides a by-product comprising a polyaniline-containing aqueous solution in which microparticles are suspended.

Both the non-aqueous and aqueous solutions of polyaniline are formed in situ and used as such as compositions for producing cast products such as films, fibers, or for mixing with other polymer and paint compositions. it can.

The present invention also relates to a process for producing polyaniline from aniline monomers, which process does not produce insoluble solids after oxidative polymerization and requires filtration, washing, drying and optionally grinding the solids. There is no way to provide.

The present invention further provides a method for producing a desired clear polyaniline solution formed in situ.

In one aspect of the present invention, a method for preparing a conductive polyaniline comprises the steps of: mixing together an aniline monomer, a water-immiscible organic solvent, at least one protonic acid doping agent, and water. Forming an emulsion by stirring and stirring; stopping the stirring to separate the emulsion into an aqueous phase and a non-aqueous phase; separating the non-aqueous phase from the aqueous phase; and adding an oxidizing agent to the non-aqueous phase. A step of polymerizing the aniline monomer.

In another aspect of the present invention, a transparent polyaniline solution formed in a non-aqueous in situ contains polyaniline doped with a protic acid prepared by the following steps. Mixing the aniline monomer, the water-immiscible organic solvent, at least one protic acid doping agent, and water together to form an emulsion; and stopping the stirring to bring the emulsion into an aqueous phase and a non-aqueous phase. Separating the non-aqueous phase from the aqueous phase; and adding an oxidizing agent to the non-aqueous phase to polymerize the aniline monomer.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments. As described above, the present invention has the first
Also provided is a method wherein the polyaniline doped with the protonic acid produced by oxidative polymerization is dissolved in the non-aqueous or oily phase of the reaction mixture so that no solids are formed during the polymerization. Polyaniline is highly soluble in the non-aqueous phase. High polyaniline solubility is achieved by adjusting the proportion of the acid dopant and by carefully choosing the organic solvent.

The polyaniline produced by the method of the present invention has the following formula:

Embedded image (Wherein R1 and R2 are alkyl, alkoxy, alkylsulfonyl, arylsulfonyl, halogen, alkoxycarbonyl, alkylthio, alkylsulfuryl,
Represents any substituent including a sulfonyl- or carboxy-substituted alkyl or aryl substituent such as cycloalkyl, p-aminophenylsulfate and p-aminophenylcarboxylic acid, and n represents an integer of 0 to 5) It can be produced by polymerization of unsubstituted or substituted aniline monomers.

The organic solvent used in the method of the present invention is a substituted or unsubstituted aromatic compound such as benzene, toluene, p-xylene, m-xylene, naphthalene, ethylbenzene, styrene, ethyl acetate, n-propyl acetate, isopropyl acetate. , N-butyl acetate, isobutyl acetate, n-acetic acid
Liquid esters such as pentyl, cyclic compounds such as cyclic hexane, methylcyclohexane and aminocyclohexane; higher ketones such as hexanone, butanone and pentanone; heterocyclic compounds such as tetrahydrofuran and hexahydropyridine; phenol; m-cresol; Cresol, chlorophenol, p-isobutylphenol,
substituted and unsubstituted phenolic compounds such as p-tert-butylphenol and p-sulfonylphenol, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene,
It is preferably selected from the group consisting of halogenated aromatic compounds such as p-dichlorobenzene; and mixtures thereof; toluene, xylene, benzene, n-butyl acetate,
Methylcyclohexane and dimethylcyclohexane are more preferred, and toluene is particularly preferred.

As the doping agent used in the method of the present invention, ordinary protonic acids are suitable. Doping agent is HC
1, H2SO4, boric acid, phosphoric acid, selenic acid, sulfuric acid, persulfuric acid, toluenesulfonic acid, benzenesulfonic acid, xylenesulfonic acid (XSA), and dodecylbenzenesulfonic acid (DBSA). More preferably, it is more preferably selected from the group consisting of HCl, toluenesulfonic acid, benzenesulfonic acid, xylenesulfonic acid (XSA), and dodecylbenzenesulfonic acid (DBSA), and HCl, DBSA, and xylenesulfonic acid (XSA) Is particularly preferred.

The oxidizing agent used in the method of the present invention includes ammonium peroxysulfate (ammonium peroxysulfate, APS), persulfates such as ammonium persulfate and potassium persulfate, perchlorates such as potassium perchlorate; potassium chloride and the like. And iodinated salts such as potassium iodide, iron (II) chloride, fuming sulfuric acid, and ozone. In particular, APS can be used.

The polymerization temperature in the process of the present invention is from 25 to 6
It can vary between 0 ° C. However, the preferred temperature has been found to be about 40 ° C. The polymerization is preferably performed at a pH of 1 or less. The following examples illustrate preferred embodiments of the present invention.

(Example 1) 10 g of concentrated hydrochloric acid, 5 g of DBSA
And 40 g of water were placed in the flask to prepare an aqueous solution.
5 g of APS was dissolved in 50 g of water in a beaker to prepare an oxidizing agent aqueous solution. An aniline solution prepared from 40 g of toluene and 2 g of aniline was added to the flask. The mixture in the flask was vigorously stirred to form an emulsion. Next, after stirring was stopped, the emulsion was allowed to stand and separated into an aqueous phase and a non-aqueous phase or an oil phase. The non-aqueous phase was separated from the aqueous phase. For the polymerization, an aqueous APS solution was added dropwise to the non-aqueous phase with stirring. The reaction mixture was stirred to further form an emulsion. The reaction was performed at room temperature for 1 to 2 hours. The pH of the emulsion was controlled to 1 or less. After the polymerization, the stirring was stopped and the emulsion was allowed to stand, whereby the emulsion separated into a lower phase and an upper phase. The upper phase containing the soluble polyaniline showed transparency. No solid precipitate was observed in the upper phase with the naked eye. The polyaniline solution obtained by the above polymerization can be directly used for applications such as production of conductive paint.

Example 2 12 g of DBSA, HCl 2
Polyaniline was produced in the same manner as in Example 1, except that 00 g and 200 g of water were used for preparation in the flask, 36 g of aniline was dissolved in 120 g of toluene, and 12 g of APS was dissolved in 120 g of water. After the polymerization, a clear solution was observed in the upper phase. No solid precipitate was observed in the solution.

Example 3 72 g of DBSA, HCl 2
Polyaniline was produced in the same manner as in Example 1 except that 40 g and 1200 g of water were used for preparation in the flask, 216 g of aniline was dissolved in 720 g of toluene, and 72 g of APS was dissolved in 720 g of water.
After the polymerization, a clear solution was obtained in the upper phase. No solid precipitate was observed in the solution.

Example 4 A polyaniline was produced in the same manner as in Example 1 except that 1 g of xylene sulfonic acid and 3.5 g of DBSA were added to the aniline solution in the flask.

The present invention is not limited to the above embodiment,
Various modifications and changes can be made without departing from the spirit of the present invention.

[0030]

As is apparent from the above description, according to the present invention, it is possible to provide a method for producing a solution in which polyaniline is sufficiently dissolved in a mixture. Also,
The process according to the invention can obviate the use of further solvents for dissolving the polyaniline and / or the undoping or redopeing of the solid polymerization product.

Further, in the method for producing a polyaniline-containing solution from an aniline monomer, no insoluble solid substance is formed after oxidative polymerization, and there is no need to filter, wash, dry and possibly grind the solid substance, thereby simplifying the process. can do.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/42 C08K 5/42 C08L 79/00 C08L 79/00 A H01B 1/20 H01B 1/20 A F Term (reference) 4J002 CM051 DD016 DG036 DG066 DH026 DK006 EV236 FD206 GH01 GP00 GQ00 4J043 PA02 QB02 RA01 SA05 SB01 UA121 XA12 XA13 XA14 XA17 XA19 XA28 XA34 XB13 XB15 YB05 YB13 ZA42 ZB01 DA03

Claims (12)

[Claims] 1. An emulsion is formed by stirring together an aniline monomer, an organic solvent immiscible with water, at least one protonic acid doping agent, and water; And separating the non-aqueous phase from the aqueous phase; and adding an oxidizing agent to the non-aqueous phase to polymerize the aniline monomer. After adding the oxidizing agent, another emulsion is formed. Forming a non-aqueous, transparent, non-aqueous polyaniline solution formed in situ by a method for producing a conductive polyaniline-containing solution. 2. The method according to claim 1, wherein an additional amount of a doping agent is added to the non-aqueous phase to control the pH of the non-aqueous phase before polymerization. 3. The organic solvent is benzene, toluene, p
-Xylene, m-xylene, o-xylene, naphthalene, ethylbenzene, styrene, ethyl acetate, n-acetic acid
Propyl, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, cyclic hexane, methylcyclohexane, aminocyclohexane, hexanone, butanone, pentanone, tetrahydrofuran, hexahydropyridine, phenol, m-cresol, p-cresol, Chlorophenol, p-isobutylphenol,
The polyaniline-containing composition according to claim 1, wherein the polyaniline is selected from the group consisting of p-tert-butylphenol, p-sulfonylphenol, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene and a mixture thereof. Method for producing a solution. 4. The method for producing a polyaniline-containing solution according to claim 1, wherein the organic solvent is toluene. 5. The method according to claim 1, wherein the doping agent is HCl, H2SO.
4. Boric acid, phosphoric acid, selenic acid, sulfuric acid, persulfuric acid, dodecylbenzenesulfonic acid (DBSA), toluenesulfonic acid, benzenesulfonic acid and xylenesulfonic acid (XS
The method for producing a polyaniline-containing solution according to claim 1, wherein the method is selected from the group consisting of A). 6. The method for producing a polyaniline-containing solution according to claim 5, wherein the doping agent includes HCl and DBSA. 7. The method according to claim 1, wherein the doping agent further comprises XS
The method for producing a polyaniline-containing solution according to claim 6, wherein A is contained. 8. The method according to claim 1, wherein the oxidizing agent is ammonium peroxysulfate (APS), ammonium persulfate, potassium persulfate,
The method for producing a polyaniline-containing solution according to claim 1, wherein the method is selected from the group consisting of potassium perchlorate, potassium chloride, potassium iodide, iron (II) chloride, fuming sulfuric acid, and ozone. 9. The method for producing a polyaniline-containing solution according to claim 8, wherein the oxidizing agent is APS. 10. The method for producing a polyaniline-containing solution according to claim 9, wherein the pH of the non-aqueous phase is 1 or less. 11. The method for producing a polyaniline-containing solution according to claim 1, wherein the weight ratio between the aniline monomer and the doping agent is in the range of 1: 1 to 100: 1. 12. The method for producing a polyaniline-containing solution according to claim 1, wherein the polymerization is further performed by adding the oxidizing agent to the aqueous phase.