JP5289899B2 - Method for producing conductive elastomer - Google Patents

Description

  The present invention relates to a method for producing a conductive elastomer useful as a transparent conductive material used for, for example, an electrode for a touch panel.

Polyaniline is known as a useful conductive polymer because it can be synthesized relatively easily from inexpensive aniline in addition to its electrical properties and has excellent stability in air. As a method for synthesizing polyaniline, there are a method of electrolytic oxidation polymerization of aniline and a method of chemical oxidation polymerization. For example, polyaniline obtained by a conventional chemical oxidative polymerization method does not dissolve in an organic solvent and is infusible. For this reason, the field | area which is inferior to a moldability and can be applied was restricted. Under such circumstances, development of highly conductive polyaniline derivatives that are soluble in organic solvents is underway (see, for example, Patent Document 1).
Japanese National Patent Publication No. 2005-052058 JP 2006-176552 A

  Patent Document 1 discloses a polyaniline composition soluble in an organic solvent containing a polyaniline derivative and a compound having a phenolic hydroxyl group (secondary dopant). However, a molded body made of this polyaniline composition is relatively hard and brittle, although it has high conductivity. For this reason, there existed a problem that the softness | flexibility of a molded object was scarce.

On the other hand, Patent Document 2 introduces a conductive polymer obtained by doping polyaniline with a urethane-based polymer having a sulfonic acid functional group. In the conductive polymer, the urethane-based polymer is firmly bonded to the ionic part (NH ⁺ ) of polyaniline through sulfonate ions (SO ³⁻ ) by ionic bonds. However, as can be seen from the use of a conductive polymer as a semiconductive member for an electrophotographic machine, the conductivity of the conductive polymer is low. One reason for this is a method for producing a conductive polymer. That is, according to the method for producing a conductive polymer described in Patent Document 2, aniline and a urethane-based polymer are oxidatively polymerized at 15 ° C. in a mixed solvent of hydrochloric acid and an organic solvent. The polymerization temperature of polyaniline is around room temperature. For this reason, the molecular weight of the polyaniline obtained is small. Therefore, the conductivity of the conductive polymer is low. That is, the conductivity is not sufficient to use the conductive polymer as a conductive material such as an electrode or wiring.

  This invention is made | formed in view of such a situation, and makes it a subject to provide the manufacturing method of a highly flexible conductive elastomer with high electroconductivity and transparency.

  (1) In order to solve the above-mentioned problem, the method for producing a conductive elastomer according to the present invention comprises an organic protonic acid represented by the following formula (I) or a salt thereof in an organic solvent immiscible with water and a mixed solvent containing water. A polyaniline derivative synthesis step for obtaining a polyaniline derivative by chemically oxidatively polymerizing aniline at a temperature of −15 ° C. or lower in the presence, and an elastomer mixing step for mixing the polyaniline derivative and an elastomer having a urethane bond. It is characterized by having.

M (XAR _n ) _m (I)
[In the formula (I),
M is a kind selected from a hydrogen atom, an organic free radical, and an inorganic free radical;
X is an acidic group,
A is a hydrocarbon group which may contain a substituent,
R is a kind selected from -R ¹ , -OR ¹ , -COR ¹ , -COOR ¹ , -CO (COR ¹ ), and -CO (COOR ¹ ) {R ¹ is a substitution having 4 or more carbon atoms. A hydrocarbon group, silyl group, alkylsilyl group, — (R ² O) _x —R ³ group, — (OSiR ³ ₂ ) _x —OR ³ group (R ² is an alkylene group, R ³ is A hydrocarbon group which may be the same or different, x is an integer of 1 or more))
n is an integer greater than or equal to 2,
m is the valence of M. ]
According to the production method of the present invention, in the polyaniline derivative synthesis step, chemical oxidation polymerization of aniline is performed in a two-phase system of an organic solvent and water, specifically, in water droplets (W / O micelles) in oil. . Thereby, polymerization is possible even at a low temperature of −15 ° C. or lower. Further, by polymerizing aniline at −15 ° C. or lower, a very high molecular weight polyaniline derivative regularly arranged in a linear form can be obtained. Since it is linear and has a large molecular weight, the resulting polyaniline derivative has high conductivity.

  In general, a polymer having high conductivity tends to aggregate. For this reason, it is inferior to compatibility with an elastomer. In this regard, according to the production method of the present invention, an elastomer having a urethane bond is used. That is, in the elastomer mixing step, the polyaniline derivative and the elastomer having a urethane bond are mixed. At this time, the compatibility between the carbonyl group (C═O) in the elastomer and the NH group of the polyaniline derivative is improved by the hydrogen bonding interaction. Thus, a highly conductive and flexible conductive elastomer can be obtained by combining a highly conductive polyaniline derivative and a flexible elastomer. Moreover, as shown in a subsequent Example, according to the obtained conductive elastomer, a highly transparent thin film can be produced.

  According to the present invention, a conductive elastomer excellent in transparency, conductivity, and flexibility can be provided.

  The method for producing a conductive elastomer of the present invention includes a polyaniline derivative synthesis step and an elastomer mixing step. Hereinafter, each step will be described.

(1) Polyaniline derivative synthesis step This step is performed at a temperature of −15 ° C. or lower in the presence of an organic protonic acid represented by the following formula (I) or a salt thereof in a mixed solvent containing water and an organic solvent immiscible with water. In this step, a polyaniline derivative is obtained by chemical oxidative polymerization of aniline.

M (XAR _n ) _m (I)
[In the formula (I),
M is a kind selected from a hydrogen atom, an organic free radical, and an inorganic free radical;
X is an acidic group,
A is a hydrocarbon group which may contain a substituent,
R is a kind selected from -R ¹ , -OR ¹ , -COR ¹ , -COOR ¹ , -CO (COR ¹ ), and -CO (COOR ¹ ) {R ¹ is a substitution having 4 or more carbon atoms. A hydrocarbon group, silyl group, alkylsilyl group, — (R ² O) _x —R ³ group, — (OSiR ³ ₂ ) _x —OR ³ group (R ² is an alkylene group, R ³ is A hydrocarbon group which may be the same or different, x is an integer of 1 or more))
n is an integer greater than or equal to 2,
m is the valence of M. ]
The mixed solvent used for the chemical oxidative polymerization of aniline includes an organic solvent immiscible with water and water. Water may be present as an acidic aqueous solution. Moreover, water may be added as an aqueous solution in which an initiator or the like is dissolved. Examples of organic solvents that are not miscible with water include hydrocarbon solvents such as octane, hexane, heptanebenzene, toluene, xylene, ethylbenzene, and tetralin, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, methylene chloride, chloroform, Examples thereof include halogen-containing solvents such as carbon chloride, dichloroethane, trichloroethane, and tetrachloroethane, and ester solvents such as ethyl acetate. Of these, octane, toluene and the like are preferred because of their low viscosity even at low temperatures.

  Moreover, what is necessary is just to determine the mixture ratio of water and the organic solvent in a mixed solvent so that a W / O micelle may be formed. By forming W / O micelles, polymerization can be performed without freezing even at a low temperature of −15 ° C. or lower. For example, the volume ratio of water and organic solvent (water / organic solvent) may be 2/1 to 200/1.

In addition to the unsubstituted aniline, those substituted with a substituent can be used. Examples of the substituent include a linear or branched hydrocarbon group such as a methyl group, an ethyl group, a hexyl group, and an octyl group, an alkoxyl group such as a methoxy group and a phenoxy group, a halogen-containing carbonized group such as an aryloxy group and a CF ₃ group. A hydrogen group etc. are mentioned.

  The organic protonic acid represented by the above formula (I) or a salt thereof has a function of protonating (adding hydrogen ions) polyaniline and exists as a dopant (counter anion) in the polyaniline derivative. The composition ratio of polyaniline and organic protonic acid or a salt thereof is not particularly limited. The molar ratio of the monomer unit of polyaniline to the organic protonic acid or a salt thereof is 0.1 to 2, preferably 0.1 to 0.5. When there is too little organic proton acid or its salt, electroconductivity will become low. On the other hand, if the amount is too large, the ratio of polyaniline is reduced, so that the conductivity is lowered. The weight composition ratio varies depending on the molecular weight of the organic protonic acid or a salt thereof. For example, when the weight ratio of polyaniline in the polyaniline derivative is 20 to 70% by weight, the polyaniline derivative exhibits excellent electrical characteristics.

  In the above formula (I), M is a kind selected from a hydrogen atom, an organic free radical, and an inorganic free radical. Examples of the organic free radical include a pyridinium group, an imidazolium group, and an anilinium group. Examples of inorganic free radicals include sodium, lithium, potassium, cerium, and ammonium.

X is an acidic group. For example, -SO ₃ ^- group, _-PO ^{3 _2-group,} -PO 4 (OH) ^- group, -OPO ₃ ^2-group, -OPO ₂ (OH) ^- group, -COO ^- group and the like. Among these, a —SO ₃ ^— group is preferable because it has a high electronegativity and can stably maintain a doping state (ionic bond).

  A is a hydrocarbon group which may contain a substituent. For example, (i) a linear or branched alkyl group or alkenyl group having 1 to 24 carbon atoms, (ii) a cycloalkyl group which may contain a substituent such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, menthyl, (Iii) a dicycloalkyl group or polycycloalkyl group that may be condensed such as bicyclohexyl, norbornyl, adamantyl, etc., and (iv) a substituent such as phenyl, tosyl, thiophenyl, pyrrolinyl, pyridinyl, furanyl, etc. Aryl group containing an aromatic ring, (v) naphthyl, anthracenyl, fluorenyl, 1,2,3,4-tetrahydronaphthyl, indanyl, quinolinyl, indonyl and the like may be condensed diaryl group, polyaryl group, alkylaryl group, etc. Is mentioned.

R is a kind selected from -R ¹ , -OR ¹ , -COR ¹ , -COOR ¹ , -CO (COR ¹ ), and -CO (COOR ¹ ). Here, R ¹ is a hydrocarbon group that may contain a substituent having 4 or more carbon atoms, a silyl group, an alkylsilyl group, a — (R ² O) _x —R ³ group, or — (OSiR ³ ₂ ) _x —. It is a kind selected from OR ³ groups (R ² is an alkylene group, R ³ is a hydrocarbon group which may be the same or different, and x is an integer of 1 or more). Examples of when R ¹ is a hydrocarbon group include linear or branched butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, pentadecyl, eicosanyl, etc. Can be mentioned.

Of the compounds represented by the formula (I), dialkylbenzenesulfonic acid, dialkylnaphthalenesulfonic acid, sulfophthalic acid ester, and compounds represented by the following formula (II) are preferable.
M (XCR ⁴ (CR ⁵ ₂ COOR ⁶ ) COOR ⁷ ) _p (II)
In the formula (II), M is a kind selected from a hydrogen atom, an organic free radical, and an inorganic free radical, as in the above formula (I). X is also an acidic group as in the above formula (I). p is the valence of M.

R ⁴ and R ⁵ are each independently selected from a hydrogen atom, a hydrocarbon group, and an R ⁸ ₃ Si— group (R ⁸ is a hydrocarbon group, and three R ⁸ may be the same or different). It is a kind. Examples of the hydrocarbon group when R ⁴ and R ⁵ are hydrocarbon groups include a linear or branched alkyl group having 1 to 24 carbon atoms, an aryl group containing an aromatic ring, and an alkylaryl group. R ⁸ is the same as the hydrocarbon group for R ⁴ and R ⁵ .

R ⁶ and R ⁷ are each independently a hydrocarbon group or a — (R ⁹ O) _q —R ¹⁰ group. Here, R ⁹ is a hydrocarbon group or a silylene group, R ¹⁰ is a hydrogen atom, a hydrocarbon group, or an R ¹¹ ₃ Si— group (R ¹¹ is a hydrocarbon group, and three R ¹¹ are the same. Or may be different), and q is an integer of 1 or more. Note that q is preferably 1 to 10. In the case where R ⁶ and R ⁷ are hydrocarbon groups, the hydrocarbon group is a linear or branched alkyl group having 1 to 24 carbon atoms, preferably 4 or more carbon atoms, an aryl group containing an aromatic ring, or an alkylaryl group. Etc. Specific examples include a linear or branched butyl group, pentyl group, hexyl group, octyl group, decyl group, and the like. In the case where R ⁶ and R ⁷ are — (R ⁹ O) _q —R ¹⁰ group, the hydrocarbon group in the case where R ⁹ is a hydrocarbon group is a linear or branched alkylene having 1 to 24 carbon atoms. Group, an arylene group containing an aromatic ring, an alkylarylene group, an arylalkylene group, and the like. ^Further, the hydrocarbon group when R ^{10, R 11} is a hydrocarbon group ^are the same as the hydrocarbon group of R 4, ^{R 5.}

Specific examples of the — (R ⁹ O) _q —R ¹⁰ group include groups represented by the following structural formulas (a) and (b) (in the structural formulas (a) and (b), X Is an acidic group such as —SO ₃ group).

Of the compounds represented by the formula (II), a sulfosuccinic acid derivative represented by the following formula (III) is more preferable.
M (O ₃ SCH (CH ₂ COOR ¹² ) COOR ¹³ ) _m (III)
In the formula (III), M and m are the same as in the above formula (I). R ¹² and R ¹³ are each independently a hydrocarbon group or a — (R ¹⁴ O) _r —R ¹⁵ group. Here, R ¹⁴ is a hydrocarbon group or a silylene group, R ¹⁵ is a hydrogen atom, a hydrocarbon group, or an R ¹⁶ ₃ Si— group (R ¹⁶ is a hydrocarbon group, and three R ¹⁶ are the same or different. And r is an integer of 1 or more. In addition, as for r, it is desirable that it is 1-10.

The hydrocarbon group in the case where R ¹² and R ¹³ are hydrocarbon groups is the same as the hydrocarbon group of R ⁶ and R ⁷ . Specific examples include a butyl group, a hexyl group, a 2-ethylhexyl group, and a decyl group. In the case where R ¹² and R ¹³ are — (R ¹⁴ O) _r —R ¹⁵ groups, the hydrocarbon group in the case where R ¹⁴ is a hydrocarbon group is the same as R ⁹ . ^Further, the hydrocarbon group when R ^{15, R 16} is a hydrocarbon group ^are the same as R 4, ^{R 5.} Specific examples of — (R ¹⁴ O) _r —R ¹⁵ group include specific examples of — (R ⁹ O) _q —R ¹⁰ group in R ⁶ and R ⁷ (the above structural formulas (a) and (b)) and The same.

  The organic protonic acid represented by the formula (I) or a salt thereof can be produced using a known method. For example, a corresponding sulfophthalic acid ester derivative or succinic acid ester derivative can be obtained by reacting a sulfophthalic acid derivative or sulfosuccinic acid derivative with a desired alcohol. The corresponding sulfosuccinate derivative can also be obtained by hydrosulfonylating maleate with sodium bisulfite or the like.

  As the organic protonic acid represented by the formula (I) or a salt thereof, a commercially available product can be used. For example, “Aerosol OT” (sodium diisooctyl sulfosuccinate) manufactured by Wako Pure Chemical Industries, Ltd., “Ripal (registered trademark) 870P” manufactured by Lion Corporation, and the like can be given. Some commercial products have different purities, but may be appropriately selected.

  The polymerization temperature is −15 ° C. or lower. By polymerizing at a low temperature of −15 ° C. or lower, a linear and very high molecular weight polyaniline derivative can be obtained. The polymerization temperature is more preferably −20 ° C., further lower than −20 ° C., and −30 ° C. or higher.

  The initiator for chemical oxidative polymerization is not particularly limited. For example, in addition to peroxide salts such as ammonium persulfate, sodium persulfate, and potassium persulfate, ammonium dichromate, ammonium perchlorate, potassium iron (III) sulfate, iron (III) trichloride, manganese dioxide, iodic acid Inorganic compounds such as potassium permanganate can be used. Especially, the compound which can exhibit oxidation ability at the temperature of -15 degrees C or less is desirable. Further, in order to prevent unreacted initiator from being mixed into the organic phase in the mixed solvent, a water-soluble compound is desirable. Examples of satisfying these requirements include ammonium persulfate, sodium persulfate, potassium persulfate, and ammonium perchlorate. In particular, ammonium persulfate is preferred.

  Further, in order to further improve the conductivity of the resulting polyaniline derivative, during chemical oxidative polymerization, additives such as organic protonic acids or salts thereof, inorganic protonic acids or salts thereof, methanesulfonic acid, etc. other than the above formula (I) May be added.

  The polyaniline derivative synthesized in this step is presumed to have a very high molecular weight. This is apparent from the fact that in the polymerization experiment conducted by changing the polymerization temperature, the molecular weight was increased as the polymerization temperature was lowered. That is, when the polymerization temperature was changed from −5 ° C. and −10 ° C. from the high temperature side, the polyaniline derivative increased in molecular weight as the polymerization temperature decreased. For example, when the polymerization temperature is 0 ° C., the number average molecular weight is 110,000 g / mol, and when the polymerization temperature is −5 ° C., the number average molecular weight is 180,000 g / mol and when the polymerization temperature is −10 ° C., the number average particle diameter is It became 250,000 g / mol. In addition, when it superposed | polymerized at -15 degrees C or less, there were many insoluble matters and the whole molecular weight of the polyaniline derivative could not be measured by gel permeation chromatography (GPC).

(2) Elastomer mixing step This step is a step of mixing the polyaniline derivative synthesized in the previous step and an elastomer having a urethane bond. The type of elastomer having a urethane bond (hereinafter referred to as “urethane elastomer” as appropriate) is not particularly limited. For example, ether-based, ester-based, caprolactone-based, acrylic-based, aliphatic-based urethane elastomers, and those obtained by copolymerizing silicone-based polyols or fluorine-based polyols can be used. Among these, one or more selected from polyester-based urethane elastomers and polycaprolactone-based urethane elastomers are preferred because of their good compatibility with polyaniline derivatives.

The urethane elastomer desirably has at least one sulfonic acid functional group of a sulfonic acid group and a sulfonic acid group. In this case, sulfonic acid ions (SO ³⁻ ) of the urethane elastomer dope the polyaniline. For this reason, the urethane elastomer and the polyaniline derivative are firmly bonded by ionic bonding. Therefore, in addition to the urethane bond, the compatibility between the polyaniline derivative and the urethane elastomer is further improved by having a sulfonic acid functional group.

  The urethane elastomer can be obtained, for example, by reacting a polyol obtained by reacting an acid component and a glycol component with an organic polyisocyanate. In the reaction of a polyol or the like with an organic polyisocyanate, it is desirable to use a catalyst. Examples of the catalyst include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, cerium and other metals, metal alkoxides, metal salts And metal oxides. Of these, alkali metals, alkaline earth metals, zinc, titanium, lead carbonates, carboxylates, borates, silicates, oxides, and organometallic compounds are suitable.

  Examples of the acid component of the polyol include aliphatic dibasic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, dodecynylsuccinic acid, 1,2-cyclohexanedicarboxylic acid, and 1,3-cyclohexanedicarboxylic acid. Such as acid, 1,4-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2-bis (4-carboxycyclohexyl) methane, 2,2bis (4-carboxycyclohexyl) propane And aromatic dicarboxylic acids such as terephthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid and naphthalenedicarboxylic acid. These may be used alone or in combination of two or more. Of these, adipic acid, sebacic acid, dodecinyl succinic acid, and 1,2-cyclohexanedicarboxylic acid are preferable from the viewpoint of dispersibility. When a sulfonic acid functional group is introduced into the skeleton, an aromatic dicarboxylic acid containing a sulfonic acid metal salt such as 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, or sodium sulfoterephthalic acid may be copolymerized. .

  Examples of the glycol component of the polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl Aliphatic glycols such as -3-hydroxypropyl, 2 ', 2'-dimethyl-3-hydroxypropanate, 2,2-diethyl-1,3-propanediol, and 1,3-bis (hydroxymethyl) cyclohexane 1,4-bis (hydroxymethyl) cyclohexane, 1,4-bis (hydroxy Til) cyclohexane, 1,4-bis (hydroxypropyl) cyclohexane, 1,4-bis (hydroxymethoxy) cyclohexane, 1,4-bis (hydroxyethoxy) cyclohexane, 2,2-bis (4-hydroxymethoxycyclohexyl) propane 2,2-bis (4-hydroxyethoxycyclohexyl) propane, bis (4-hydroxycyclohexyl) methane, alicyclic glycols such as 2,2-bis (4-hydroxycyclohexyl) propane, and the like. These may be used alone or in combination of two or more. Among them, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2-dimethyl-3-hydroxypropyl, 2 ', 2'-dimethyl-3- Hydroxypropanate and 1,6-hexanediol are preferred. When a sulfonic acid functional group is introduced into the skeleton, a sulfonic acid metal salt-containing glycol such as 2-sodium sulfo-1,4-butanediol or 2-sodium sulfo-1,6-hexanediol may be copolymerized. .

  Examples of the organic polyisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, m-phenylene diisocyanate, and 3,3′-dimethoxy-4. , 4'-biphenylene diisocyanate, 2,6-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-diphenylene diisocyanate, 4,4'-diisocyanate diphenyl ether, 1,5- Naphthalene diisocyanate, m-xylene diisocyanate, 1,3-diisocyanate methylcyclohexane, 1,4-diisocyanate methyl xylohexane, 4,4'-diisocyanate cyclohexane, 4,4 - diisocyanate cyclohexylmethane, isophorone diisocyanate, and the like. These may be used alone or in combination of two or more. Of these, 4,4′-diphenylmethane diisocyanate is preferred.

  The polyaniline derivative and the urethane elastomer may be mixed by, for example, mixing a solution in which the polyaniline derivative is dissolved in a predetermined organic solvent and a solution in which the urethane elastomer is dissolved in the predetermined organic solvent. Further, both may be carried out by mixing (dry blending) a solid polyaniline derivative and a urethane elastomer. By mixing each other in the form of a solution, the transparency of the thin film produced from the obtained conductive elastomer can be improved. Moreover, when the mutual solvent is the same, the compatibility is improved, so that the transparency of the thin film is further increased. The solvent for dissolving the polyaniline derivative may be the same as or different from the organic solvent used for the chemical oxidative polymerization.

  The polyaniline derivative and the urethane elastomer are desirably blended so that the polyaniline is 3% by weight or more and 50% by weight when the total of the polyaniline derivative and the urethane elastomer is 100% by weight. When polyaniline is less than 3% by weight, the flexibility of the conductive elastomer is improved, but the conductivity is lowered. On the other hand, when the polyaniline is more than 50% by weight, the conductivity of the conductive elastomer is improved, but the flexibility is lowered. That is, the conductive elastomer becomes hard and brittle.

  (3) The method for producing a conductive elastomer of the present invention can be configured to further include a secondary dopant addition step in addition to the above two steps. That is, the secondary dopant addition step is performed between the polyaniline derivative synthesis step and the elastomer mixing step or after the elastomer mixing step. In the secondary dopant addition step, a compound having a phenolic hydroxyl group is added as a secondary dopant to a polyaniline derivative or a mixture of a polyaniline derivative and an elastomer having a urethane bond. The compound having a phenolic hydroxyl group functions as a dopant together with the organic protonic acid or a salt thereof. Therefore, the conductivity of the resulting conductive elastomer is further improved by adding a compound having a phenolic hydroxyl group.

  The compound having a phenolic hydroxyl group is a compound represented by the general formula ArOH (Ar is an aryl group or a substituted aryl group). Specifically, phenol, o-, m-, p-cresol, o-, m-, p-ethylphenol, o-, m-, p-propylphenol, o-, m-, p-butylphenol, o Substituted phenols such as-, m-, p-chlorophenol, salicylic acid, hydroxybenzoic acid and hydroxynaphthalene, polyhydric phenol compounds such as catechol and resorcinol, polymer compounds such as phenol resin, polyphenol and poly (hydroxystyrene), etc. Is mentioned.

  The addition amount of the compound having a phenolic hydroxyl group (secondary dopant) is desirably 0.01 to 1000% by weight when the whole polyaniline derivative is 100% by weight. More preferably, the content is 0.5 to 500% by weight. When there is too little addition amount of a secondary dopant, the electroconductive improvement effect will not be acquired. Moreover, when too large, there exists a possibility that the uniformity and transparency of a conductive elastomer may fall.

  (4) The conductive elastomer obtained by the production method of the present invention can be formed into a thin film, for example. In this case, a solution obtained by dissolving a conductive elastomer in a solvent is used as a spin coat method, spray method, ink jet method, dip method, cast method, doctor blade method, bar code method, screen printing method, gravure printing method, Langmuir brodid. (LB) What is necessary is just to form into a film using well-known methods, such as a film formation method and a centrifugal molding method. Moreover, you may shape | mold by the extrusion molding method, the injection molding method, the inflation molding method, etc.

  Next, the present invention will be described more specifically with reference to examples.

<Production of polyaniline derivative>
First, 22.2 g (50 mmol) of sodium diisooctylsulfosuccinate (“Aerosol OT” manufactured by Wako Pure Chemical Industries, Ltd.) was added to 237 mL of isooctane, and dissolved by stirring. Subsequently, an aqueous ammonium persulfate solution (5.71 g (25 mmol) of ammonium persulfate / 13 mL of water) was added to this solution at −10 ° C. to form W / O micelles. Further, 4.81 g (50 mmol) of methanesulfonic acid was added to the same solution. Next, while this solution was stirred at −20 ° C., 2.33 g (25 mmol) of aniline / 37 mL of ethanol / 200 mL of isooctane was added dropwise to initiate chemical oxidative polymerization. The polymerization was carried out for 24 hours. After completion of the polymerization, the reaction solution was transferred to a separating funnel, the aqueous phase was removed from the reaction solution separated into two layers, and the organic phase was washed twice with ion-exchanged water and twice with 1N hydrochloric acid. Volatile components (organic solvent) were distilled off from the solution containing the desired product under reduced pressure to obtain a solid polyaniline derivative.

<Manufacture of urethane elastomer>
(1) Polycaprolactone-based urethane elastomer First, 90 parts by weight of polycaprolactone diol (number average molecular weight: 2000) was dissolved in methyl ethyl ketone (MEK) so that the solid content was 30% by weight. Next, 0.02 part by weight of catalyst dibutyltin dilaurate was added, and 12.5 parts by weight of 4,4′-diphenylmethane diisocyanate was added while stirring at 80 ° C. 59 parts by weight was added to obtain a polycaprolactone urethane elastomer (number average molecular weight: 65,000). The structural formula of the obtained polycaprolactone-based urethane elastomer is shown in the following structural formula (c). In the structural formula (c), m: n: p = 1: 10: 170.

(2) Polyester urethane elastomer First, 84.1 parts by weight of 5-sodium sulfoisophthalic acid, 155.8 parts by weight of 1,6-hexanediol, and 321.7 parts by weight of neopentyl glycol were mixed and mixed at 5 ° C at 200 ° C. The transesterification reaction was performed for a time. Subsequently, 334.7 parts by weight of adipic acid and 224.3 parts by weight of terephthalic acid were added and reacted at 200 ° C. for 10 hours. Thereafter, the reaction system is depressurized to about 0.27 × 10 ⁵ Pa over 3 hours, and further subjected to a polycondensation reaction at about 6.67 × 10 ^{2 to} 0.27 × 10 ⁴ Pa at 210 ° C. for 2 hours. Diol (number average molecular weight: 2000) was obtained. Next, 90 parts by weight of the obtained polyester diol was dissolved in MEK so that the solid content was 30% by weight. Then, 0.02 part by weight of dibutyltin dilaurate as a catalyst was added, 12.5 parts by weight of 4,4′-diphenylmethane diisocyanate was added while stirring at 80 ° C., and 1.18 of 1,6-hexanediol was further added. By adding parts by weight, a polyester urethane elastomer having a sulfonic acid functional group (number average molecular weight: 50,000, sulfonic acid functional group amount: 0.2 mmol / g) was obtained. The structural formula of the obtained polyester urethane elastomer is shown in the following structural formula (d). In the structural formula (d), X: Y: Z: m: n: p = 4.3: 9.6: 8.2: 1: 2: 7.3.

<Manufacture of conductive elastomer>
(1) Example First, 30 parts by weight of the produced polyaniline derivative was dissolved in 600 parts by weight of toluene to prepare a 5% by weight toluene solution of the polyaniline derivative. In addition, 70 parts by weight of the two types of urethane elastomer produced were each dissolved in 1500 parts by weight of tetrahydrofuran (THF) to prepare two types of elastomer THF solutions. Next, the toluene solution of the polyaniline derivative was added to each of the two types of elastomer THF solutions, stirred, and then ultrasonically dispersed. Furthermore, 120 parts by weight of a secondary dopant, m-cresol, was added and ultrasonically dispersed to obtain two types of conductive elastomers having different elastomer types. A conductive elastomer using a polycaprolactone-based urethane elastomer was taken as Example 1, and a conductive elastomer using a polyester-based urethane elastomer was taken as Example 2.

(2) Comparative Example A conductive polymer was produced in the same manner as in the above Example except that polybutyl acrylate was used instead of the urethane elastomer. The obtained conductive polymer was referred to as Comparative Example 1.

Moreover, the conductive polymer was manufactured by the method different from an Example. First, a polyester urethane elastomer was produced. 178 parts by weight of 5-sodium sulfoisophthalic acid, 155.8 parts by weight of 1,6-hexanediol, and 321.7 parts by weight of neopentyl glycol were mixed and subjected to transesterification at 200 ° C. for 5 hours. Subsequently, 480.8 parts by weight of adipic acid was added and reacted at 200 ° C. for 10 hours. Thereafter, the reaction system is depressurized to about 0.27 × 10 ⁵ Pa over 3 hours, and further subjected to a polycondensation reaction at about 6.67 × 10 ^{2 to} 0.27 × 10 ⁴ Pa at 210 ° C. for 2 hours. Diol (number average molecular weight: 2000) was obtained. Next, 100 parts by weight of the obtained polyester diol was dissolved in MEK so that the solid content was 30% by weight. Then, 0.02 part by weight of dibutyltin dilaurate as a catalyst is added, and 12.5 parts by weight of 4,4′-diphenylmethane diisocyanate is added while stirring at 80 ° C. to obtain a polyester-based urethane elastomer having a sulfonic acid functional group. (Number average molecular weight: 20,000, sulfonic acid functional group amount: 0.5 mmol / g) was obtained.

  Next, 93 g of aniline, 1333 g of the obtained urethane elastomer, 6000 mL of MEK, and 6000 mL of IN hydrochloric acid were placed in a flask. Then, while stirring at 15 ° C., 228.2 g of ammonium persulfate dissolved in 1000 mL of IN hydrochloric acid was added dropwise over 1 hour, and chemical oxidative polymerization was performed for 20 hours. After completion of the polymerization, the polymer was washed with water and methanol and dried to obtain a conductive polymer. The obtained conductive polymer was referred to as Comparative Example 2.

<Evaluation method>
A thin film was produced from the produced conductive elastomer and conductive polymer (hereinafter referred to as “conductive elastomer etc.” as appropriate), and the physical properties of the thin film were evaluated. The following two types of thin films were prepared for each evaluation item. First, for evaluation of transparency and conductivity, a thin film having a film thickness shown in Table 1 below was produced by spin coating (hereinafter referred to as “thin film A”). The spin coating was performed for 1 minute at a rotation speed of 1000 rpm. Then, it was vacuum-dried at 60 ° C. for 30 minutes. Second, for evaluation of flexibility, a thin film having a thickness of about 20 μm was produced by a casting method (hereinafter referred to as “thin film B”). That is, a THF solution such as a conductive elastomer was cast on a substrate with an applicator and dried at 60 ° C. for 30 minutes.

  The evaluation items were three items of transparency, conductivity, and flexibility. Hereinafter, each evaluation method will be described.

[transparency]
The total transmittance of the thin film A was measured. The measurement was performed using an ultraviolet-visible near-infrared spectrophotometer “V-570” manufactured by JASCO Corporation. A value calculated by averaging the transmittances at wavelengths of 400 to 800 nm was defined as the total transmittance.

[Conductivity]
The conductivity of the thin film A was measured by a resistivity meter “Loresta (registered trademark) GP” manufactured by Dia Instruments Co., Ltd. (based on the four-probe method of JIS K7194 (1994)).

[Flexibility]
The tensile fracture elongation of the thin film B was measured according to JIS K 7113 (1995). The shape of the test piece was No. 1.

<Evaluation results>
The evaluation results of the thin films of Examples and Comparative Examples are shown in Table 1 together with the composition of the conductive elastomer and the like. In addition, about the thin film of the comparative example 2, since the raw material and manufacturing method of the used conductive polymer differ from another Example etc., a composition is abbreviate | omitted.

  As shown in Table 1, the total transmittance of the thin films of Examples 1 and 2 was 80% or more. That is, it can be seen that the thin films of Examples 1 and 2 have high transparency. Further, the conductivity of the thin film of Examples 1 and 2 was very high as compared with the thin film of Comparative Example 2. The thin film of Comparative Example 2 contains polyaniline and urethane elastomer, but is made of a conductive polymer manufactured by a method different from that of Examples 1 and 2. That is, it can be seen that when the production method of the present invention is employed, a highly conductive conductive elastomer can be produced. Moreover, the tensile fracture elongation of the thin films of Examples 1 and 2 was larger than that of the thin films of Comparative Examples 1 and 2. From this result, it can be seen that the thin films of Examples 1 and 2 are flexible. In particular, compared with the thin film of Comparative Example 1 that does not contain a urethane elastomer, the effect of improving flexibility is great. Thus, according to the manufacturing method of the present invention, a conductive elastomer excellent in transparency, conductivity, and flexibility could be easily manufactured.

  Since the conductive elastomer produced by the production method of the present invention has high transparency, conductivity, and flexibility, in addition to the electrode for touch panel and the transparent wiring, an electromagnetic shielding film, a thermoelectric conversion film, further a solar cell, It can be used for various applications such as a deformable display such as liquid crystal and electroluminescence (EL).

Claims (3)

Seen containing an organic solvent and water immiscible with water, mixed solvent volume ratio between water and organic solvent (water / organic solvent) is 2/1 to 200/1, represented by the following formula (I) A polyaniline derivative synthesis step for obtaining a polyaniline derivative by chemical oxidative polymerization of aniline at a temperature of −15 ° C. or lower in the presence of an organic protonic acid or a salt thereof;
An elastomer mixing step of mixing the polyaniline derivative and one or more elastomers selected from a polyester urethane elastomer having a urethane bond and a polycaprolactone urethane elastomer ;
A secondary dopant addition step in which a compound having a phenolic hydroxyl group is added as a secondary dopant between the polyaniline derivative synthesis step and the elastomer mixing step or after the elastomer mixing step;
A process for producing a conductive elastomer, comprising:
M (XAR _n ) _m (I)
[In the formula (I),
M is a kind selected from a hydrogen atom, an organic free radical, and an inorganic free radical;
X is an acidic group,
A is a hydrocarbon group which may contain a substituent,
R is a kind selected from -R ¹ , -OR ¹ , -COR ¹ , -COOR ¹ , -CO (COR ¹ ), and -CO (COOR ¹ ) {R ¹ is a substitution having 4 or more carbon atoms. A hydrocarbon group, silyl group, alkylsilyl group, — (R ² O) _x —R ³ group, — (OSiR ³ ₂ ) _x —OR ³ group (R ² is an alkylene group, R ³ is A hydrocarbon group which may be the same or different, x is an integer of 1 or more))
n is an integer greater than or equal to 2,
m is the valence of M. ] The method for producing a conductive elastomer according to claim 1, wherein the elastomer having a urethane bond is one or more selected from the polycaprolactone-based urethane elastomer. The method for producing a conductive elastomer according to claim 1, wherein the elastomer having a urethane bond further has a sulfonic acid functional group.