JP2010100838A - Electroconductive coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroconductive coating composition in which the long-term preservability of the composition in a solution is good, which dissolves in an organic solvent not having a hydrophilic group of strong acidity represented by sulfonic acid, and which can simply form a coating film by coating. <P>SOLUTION: The electroconductive coating composition includes: a π conjugated polymer compound; a dopant; and an organic solvent, wherein the dopant is a quinone compound (Q) expressed by general formula (1). In the formula, X<SP>1</SP>-X<SP>4</SP>are each a hydroxy group or a chlorine atom, two of X<SP>1</SP>-X<SP>4</SP>are a hydroxy group, and remaining two are a chlorine atom. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a conductive coating composition. More specifically, the present invention relates to a conductive coating composition containing a π-conjugated polymer compound and a dopant having a specific chemical structure, and a conductive film obtained therefrom.

In recent years, attempts have been made to develop conductive polymer compounds that can impart conductivity at low temperatures on flexible substrates, and application to conductive functional materials, light-emitting functional materials, photoelectric conversion functional materials, and the like is expected.
Conventionally, it is known that a compound having a sulfonic acid group as a dopant is suitable as a π-conjugated polymer conductive composition that gives a conductive film (see, for example, Patent Documents 1 and 2).
Patent Document 1 proposes a water-dispersed colloidal coating liquid using polystyrene sulfonic acid as a dopant. However, the above coating solution is extremely hydrophilic, and the conductive film produced using this coating has a high hygroscopic property. This causes a problem, and strongly acidic hydrogen ions generated by the moisture absorption corrode the metal in contact with the film. There is a problem to do. In addition, this coating solution has a problem in long-term storage stability, such as agglomeration and sedimentation unless it is stored at a low temperature.

  Patent Document 2 proposes a method using a polycondensation compound having a sulfonic acid group as a dopant, and a film showing good conductivity is obtained by performing electrolytic oxidation polymerization. However, the compound disclosed in Patent Document 2 has a problem in that the film is directly formed by electrolytic oxidation polymerization, and the process is complicated and the film can be formed only on a conductive surface.

Japanese Patent Laid-Open No. 7-90060 JP 2007-224182 A

  The present invention has been made in view of the above problems, and the present invention has good long-term storage stability of a solution composition and can be dissolved in an organic solvent without having a strongly acidic hydrophilic group typified by sulfonic acid. An object of the present invention is to provide a conductive coating composition capable of easily forming a film by coating.

  The inventors of the present invention have reached the present invention as a result of studies to achieve the above object. That is, the present invention is a conductive coating composition containing a π-conjugated polymer compound, a dopant and an organic solvent, wherein the dopant is a quinone compound (Q) represented by the general formula (1). The conductive coating composition is characterized.

[Wherein, X ^{1 to} X ⁴ are each a hydroxyl group or a chlorine atom, two of X ^{1 to} X ⁴ are a hydroxyl group, and the remaining two are a chlorine atom. ]

According to the present invention, a conductive coating composition soluble in an organic solvent can be provided.
Since this conductive coating composition does not have a strongly acidic hydrophilic group, it can also be used for applications where it comes into contact with metals that are a concern for corrosiveness. Because it is good, it can be used in a single solution.
In addition to antistatic applications, a wiring pattern can be arbitrarily formed, so that a conductive coating composition that can contribute to many industrial fields such as electronic device applications can be provided.

  The conductive coating composition of the present invention is a conductive coating composition containing a π-conjugated polymer compound, an organic solvent and a dopant, and the dopant is a quinone compound (Q) having a specific chemical structure. It is characterized by.

  The dopant used in the present invention is a quinone compound (Q) represented by the following general formula (1).

In the formula, X ^{1 to} X ⁴ are each a hydroxyl group or a chlorine atom, two of X ^{1 to} X ⁴ are hydroxyl groups, and the remaining two are chlorine atoms.

  Conventionally, p-chloranil, p-benzoquinone, p-quinonedioxime, dichlorodicyanoquinone (hereinafter abbreviated as DDQ), p-naphthoquinone, anthraquinone, chloroanthraquinone, It is known to add a quinone compound such as p-toluquinone as a dopant. However, when these are used, it becomes insoluble and cannot be applied as a solution, or the conductivity is improved by doping. There is a problem in that it is insufficient.

On the other hand, by using the quinone compound (Q) represented by the general formula (1) in the present invention as a dopant, it is possible to obtain a conductive coating composition that satisfies all the performances such as storage stability and conductivity. It becomes possible.
A preferred dopant in the present invention is chloranilic acid represented by the following structural formula (2). This chloranilic acid is commercially available.

  The π-conjugated polymer compound in the present invention donates electrons to the dopant and forms a charge transfer complex together with the dopant. Since this charge transfer complex exhibits conductivity as an electron carrier, the larger the amount of dopant used, the better. However, even if it is excessive, the film quality deteriorates and the conductivity decreases. Therefore, the amount of the dopant used is preferably 0.001 to 2 mol, more preferably 0.05 to 0.2 mol, per 1 mol of the monomer (repeating unit) constituting the π-conjugated polymer compound.

  As the π-conjugated polymer compound, known π-conjugated polymer compounds (for example, polythiophene, polyaniline, polypyrrole, polyacetylene, polyisothianaphthene, etc.) can be used, but they are substituted from the viewpoint of solvent solubility. Polythiophene is preferable, and more preferable is an alkyl group having 6 to 12 carbon atoms (n- or iso-hexyl group, n- or iso-heptyl group, n- or iso-octyl group, 2-ethylhexyl group, n- or iso-nonyl group, n- or iso-decyl group, n- or iso-undecyl group and n- or iso-dodecyl group) or a polythiophene substituted with a substituent represented by the general formula (3) .

In the formula, R ¹ represents an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 6.
Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n- or iso-propyl group, n-, sec-, iso- or tert-butyl group, n- or iso-pentyl group and n- or An iso-hexyl group etc. are mentioned. Of these, a methyl group is preferred from the viewpoint of solubility.

  Among these substituents, preferred are n-hexyl group, n-dodecyl group, hexyloxy group [general formula (3) (the same applies hereinafter) R1 = hexyl group, n = 0], 2,5,8-trio. Xaoctyl group (R1 = methyl group, n = 2), 2,5,8,11-tetraoxaundecyl group (R1 = methyl group, n = 3), 2,5,8,11,14,17, It is a 20-heptaoxaeicosyl group (R1 = methyl group, n = 6).

  The polythiophene can be obtained by polymerizing monomers as raw materials. The polymerization can be performed by a known method such as anionic polymerization or oxidative polymerization.

  Examples of the raw material monomer for polythiophene in the present invention include compounds having a thiophene skeleton. For example, 3-alkylthiophenes such as 3-n-hexylthiophene and 3-n-dodecylthiophene; 3-hexyloxythiophene having the general formula (3) as a substituent, 3- (2,5,8-trioxaoctyl) 3-alkoxythiophene such as thiophene, 3- (2,5,8,11-tetraoxaundecyl) thiophene and 3- (2,5,8,11,14,17,20-heptaoxaeicosyl) thiophene However, it is not limited to these. These may be used alone or in combination of two or more.

  As the organic solvent in the present invention, a solvent that dissolves the π-conjugated polymer compound and the dopant well and has an appropriate drying rate at the time of coating is desired.

  Examples of such organic solvents include C1-C10 chlorine-based, amide-based, ether-based, aromatic hydrocarbon-based, alcohol-based, ketone-based, or sulfur-based solvents. Preferred examples include chloroform, Examples include methylene chloride, dimethylformamide (hereinafter abbreviated as DMF), dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, 1,3-dioxolane, toluene, methanol, acetone, dimethyl sulfoxide, and mixtures thereof. From the viewpoint, a mixed solvent of chloroform and DMF is more preferable.

In order to dissolve a π-conjugated polymer compound and a dopant in an organic solvent to form a conductive coating composition, the π-conjugated polymer compound and the dopant can be dissolved together in the organic solvent, but they are insoluble during mixing. From the viewpoint of preventing generation of a product, it is preferable to dissolve the π-conjugated polymer compound and the dopant in an organic solvent and mix the respective solutions. The organic solvent to be used may be used alone or in combination of two or more if compatible.
If the concentration of each solution is too high, insoluble matter may be generated at the time of mixing. Therefore, it is desirable that the concentration of the solution is dilute, but if the concentration is too low, the film-forming property at the time of application deteriorates. Accordingly, the concentration of each solution is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, and particularly preferably 0.1 to 2% by weight.

  The conductive coating composition obtained by dissolving in a solvent as described above is applied to a substrate by a method such as dip coating, spin coating, blade coating, and printing, and then the solvent is dried and removed. Can be obtained.

  The conductive film formed by applying the conductive coating composition of the present invention can be used as a solid electrolyte of a solid electrolytic capacitor.

  The conductive film formed by applying the conductive coating composition of the present invention is a touch panel in which a pair of panel plates having a conductive layer are arranged so that the conductive layers face each other with a spacer interposed therebetween. The conductive layer can be used.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these.

<Production Example 1>
Synthesis of poly-3- (2,5,8-trioxaoctyl) thiophene represented by the following structural formula (4):
Macromolecules, Vol. 26, pages 2234 to 2239, 3-bromothiophene (manufactured by Aldrich), diethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), sodium hydride (manufactured by Wako Pure Chemical Industries, Ltd.), copper iodide 3- (2,5,8-trioxaoctyl) thiophene, a monomer, was obtained from (I) (Wako Pure Chemical Industries, Ltd.) and the like.
5 parts of the obtained 3- (2,5,8-trioxaoctyl) thiophene and 5 parts of iron (III) chloride were dissolved in 50 parts of chloroform and stirred at room temperature for 2 hours. The resulting mixture was concentrated with an evaporator and then subjected to Soxhlet extraction with 150 ml of chloroform, and chloroform was distilled off to obtain 4.1 parts of poly-3- (2,5,8-trioxaoctyl) thiophene (yield). Rate: 82%).

<Production Example 2>
Synthesis of poly-3- (2,5,8,11-tetraoxaundecyl) thiophene represented by the following structural formula (5):
The same operation as in Production Example 1 was performed except that diethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to triethylene glycol monomethyl ether (manufactured by Sankyo Chemical Co., Ltd.) in Production Example 1, and poly-3- (2,5 , 8,11-tetraoxaundecyl) thiophene.

<Production Example 3>
Synthesis of poly-3- (2,5,8,11,14,17,20-heptaoxaeicosyl) thiophene represented by the following structural formula (5):
Except that diethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to hexaethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) in Production Example 1, the same operation as in Production Example 1 was carried out to obtain poly-3- (2, 5, 8,11,14,17,20-Heptaoxaeicosyl) thiophene was obtained.

Example 1
0.005 g of poly-3- (2,5,8-trioxaoctyl) thiophene was dissolved in 0.5 ml of chloroform. Further, 0.005 g of chloranilic acid was dissolved in 0.5 ml of DMF. By mixing these, the conductive coating composition of the present invention was obtained.
Moreover, when this composition was allowed to stand at room temperature for 1 hour, 6 hours, and 7 days and the appearance was confirmed, it remained a uniform liquid.

The composition after standing for 7 days was applied to a 3 cm × 7 cm rectangular pattern on a glass substrate using a doctor blade so that the film thickness after drying was 0.4 μm, and the film was obtained by natural drying. .
The surface resistance of the film was measured in accordance with JIS K 7194 “Resistivity Test Method Using Conductive Plastic 4-Probe Method” and found to be 30 kΩ / □. The electrical conductivity was 0.8 S / cm as a result of calculating from the following mathematical formula.

Example 2
The same operation as in Example 1 was performed except that the amount of chloroform used was 0.05 ml and the amount of chloranilic acid used was 0.0005 g in Example 1, to obtain the conductive coating composition of the present invention. .
The appearance of the composition after standing at room temperature for 1 hour, 6 hours and 7 days remained a uniform liquid.
The composition after standing for 7 days was applied to a 3 cm × 7 cm rectangular pattern on a glass substrate using a doctor blade so that the film thickness after drying was 0.2 μm, and the film was obtained by natural drying. .
The film surface resistance was 100 kΩ / □, and the conductivity was 0.5 S / cm.

Example 3
Example 1 except that poly-3- (2,5,8-trioxaoctyl) thiophene was replaced with poly-3- (2,5,8,11-tetraoxaundecyl) thiophene in Example 1. The conductive coating composition of the present invention was obtained in the same manner as described above.
The appearance of the composition after standing at room temperature for 1 hour, 6 hours and 7 days remained a uniform liquid.
The composition after standing for 7 days was used in the same manner as in Example 2 to obtain a film. The thickness of the coating was 0.2 μm, the surface resistance was 80 kΩ / □, and the conductivity was 0.6 S / cm.

Example 4
0.005 g of poly-3- (2,5,8,11-tetraoxaundecyl) thiophene was dissolved in 0.5 ml of 1,3-dioxolane. Further, 0.005 g of chloranilic acid was dissolved in 0.5 ml of methanol. By mixing these, the conductive coating composition of the present invention was obtained.
The appearance of the composition after standing at room temperature for 1 hour, 6 hours and 7 days remained a uniform liquid.
The composition after standing for 7 days was used in the same manner as in Example 2 to obtain a film. The thickness of the film was 0.2 μm, the surface resistance was 70 kΩ / □, and the conductivity was 0.7 S / cm.

Example 5
In Example 1, 0.005 g of poly-3- (2,5,8-trioxaoctyl) thiophene was converted to poly-3- (2,5,8,11,14,17,20-heptaoxaeicosyl) thiophene. Except having replaced with 0.0075g, operation similar to Example 1 was performed and the electroconductive coating composition of this invention was obtained.
The appearance of the composition after standing at room temperature for 1 hour, 6 hours and 7 days remained a uniform liquid.
The composition after standing for 7 days was used in the same manner as in Example 2 to obtain a film. The thickness of the film was 0.2 μm, the surface resistance was 100 kΩ / □, and the conductivity was 0.5 S / cm.

Example 6
Poly-3- (2,5,8,11,14,17,20-heptaoxaeicosyl) thiophene (0.0075 g) was dissolved in methanol (0.15 ml). Further, 0.005 g of chloranilic acid was dissolved in 0.15 ml of methanol. By mixing these, the conductive coating composition of the present invention was obtained.
The appearance of the composition after standing at room temperature for 1 hour, 6 hours and 7 days remained a uniform liquid.
The composition after standing for 7 days was applied to a 3 cm × 7 cm rectangular pattern on a glass substrate using a doctor blade so that the film thickness after drying was 0.5 μm, and the film was obtained by natural drying. .
The surface resistance of the film was 40 kΩ / □, and the conductivity was 0.5 S / cm.

Comparative Example 1
A conductive coating composition was produced in the same manner as in Example 1 except that chloranilic acid was replaced with DDQ.
When this composition was allowed to stand at room temperature for 1 hour and then visually observed for appearance, it was found that agglomerated fine powder was slightly mixed and dispersed.
In addition, the appearance after standing for 6 hours was such that the above-mentioned aggregated fine powder increased and settled, and a supernatant was observed. Furthermore, the appearance after standing for 7 days was a state where the solid-liquid separation was completely performed on the gel-like aggregates on the bottom of the container and the colorless and transparent supernatant.
A coating film was obtained using the composition after standing for 1 hour in the same manner as in Example 1. The conductivity of the coating was 0.04 S / cm. However, an attempt was made to coat the composition after standing for 6 hours, but it was impossible to form a uniform film because the mixed fine powder was an obstacle.

Comparative Example 2
A conductive coating composition was produced in the same manner as in Example 4 except that chloranilic acid was replaced with DDQ.
When this composition was allowed to stand at room temperature for 1 hour and then visually observed for appearance, it was found that agglomerated fine powder was slightly mixed and dispersed.
In addition, the appearance after standing for 6 hours was such that the above-mentioned aggregated fine powder increased and settled, and a supernatant was observed. Furthermore, the appearance after standing for 7 days was a state where the solid-liquid separation was completely performed on the gel-like aggregates on the bottom of the container and the colorless and transparent supernatant.
A coating film was obtained using the composition after standing for 1 hour in the same manner as in Example 1. The conductivity of the coating was 0.02 S / cm. However, an attempt was made to coat the composition after standing for 6 hours, but it was impossible to form a uniform film because the mixed fine powder was an obstacle.

Comparative Example 3
A conductive coating composition was produced in the same manner as in Example 6 except that chloranilic acid was replaced with DDQ.
When this composition was allowed to stand at room temperature for 1 hour and then visually observed for appearance, it was found that agglomerated fine powder was slightly mixed and dispersed.
In addition, the appearance after standing for 6 hours was such that the above-mentioned aggregated fine powder increased and settled, and a supernatant was observed. Furthermore, the appearance after standing for 7 days was a state where the solid-liquid separation was completely performed on the gel-like aggregates on the bottom of the container and the colorless and transparent supernatant.
A coating film was obtained using the composition after standing for 1 hour in the same manner as in Example 1. The conductivity of the coating was 0.01 S / cm. However, an attempt was made to coat the composition after standing for 6 hours, but it was impossible to form a uniform film because the mixed fine powder was an obstacle.

  Table 1 summarizes the appearance of the conductive coating compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3 and the electrical conductivity of the film.

  As is clear from Table 1, the compositions of Examples 1 to 6 of the present invention are in a uniform liquid state even after standing for 7 days, can form a clean film, and are excellent in storage stability. Moreover, the conductivity of the obtained film is high. On the other hand, the compositions of Comparative Examples 1 to 3 were in a state in which the appearance was slightly mixed and dispersed after standing for 1 hour, and the presence of a supernatant was observed after standing for 6 hours. Couldn't get.

  Since the conductive coating composition of the present invention can be dissolved in an organic solvent and a film can be easily formed by coating, it can be applied to conductive functional materials, light-emitting functional materials, photoelectric conversion functional materials, and the like. It can also be applied to low heat-resistant and flexible substrates such as films, and is useful for common industrial issues such as miniaturization, weight reduction, and cost reduction.

Claims (7)

A conductive coating composition comprising a π-conjugated polymer compound, a dopant and an organic solvent, wherein the dopant is a quinone compound (Q) represented by the general formula (1) Composition.
[Wherein, X ^{1 to} X ⁴ are each a hydroxyl group or a chlorine atom, two of X ^{1 to} X ⁴ are a hydroxyl group, and the remaining two are a chlorine atom. ]   The conductive coating composition according to claim 1, wherein the quinone compound (Q) is chloranilic acid.   The conductive coating composition according to claim 1, wherein the π-conjugated polymer compound is an optionally substituted polythiophene.   The organic solvent is one or more organic solvents selected from the group consisting of chloroform, methylene chloride, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, 1,3-dioxolane, toluene, methanol, acetone, dimethyl sulfoxide. The conductive coating composition according to any one of 1 to 3.   The electroconductive film obtained by apply | coating the electroconductive coating composition in any one of Claims 1-4 to a base material.   A solid electrolytic capacitor using the conductive film according to claim 5 as a solid electrolyte.   It is a touch panel which arrange | positions a pair of panel board which has a conductive layer so that conductive layers may oppose through a spacer, Comprising: At least one conductive layer uses the conductive film of Claim 5 Touch panel characterized by.