JP5210545B2 - Water-insoluble conductive polyaniline composition and film thereof - Google Patents

Description

  The present invention relates to a water-insoluble conductive polyaniline composition and a method for producing the same, and further relates to a film comprising the water-insoluble conductive polyaniline composition.

  A conductive polyaniline composition comprising a polyaniline having a dopant has attracted attention as a stable conductive polymer, and is known to be useful in various fields. For example, as a cathode material for an aluminum electrolytic capacitor or a tantalum electrolytic capacitor, it is known that an electrolytic capacitor having excellent frequency characteristics can be obtained by impregnating a device with a polyaniline solution and then doping with a protonic acid ( Patent Document 1). In addition, in many fields such as an antistatic material, an electromagnetic wave shielding material, a magnetic recording medium, a film capacitor, and a battery, researches for practical use or practical application are in progress.

  Conductive polyaniline compositions have also been found to have exceptionally high heat resistance, especially when having selected dopants, for example, polyaniline with a monosulfonic acid having a carboxyl group as a dopant is very It has been known that it has excellent heat stability, and even if it is left at a high temperature of 125 ° C. for 650 hours, the change in conductivity is within one digit (see Patent Document 2).

  However, it is known that the conductive polyaniline composition is relatively weak in terms of water resistance, which is important in practical use as well as heat resistance. By including polymer sulfonic acid as a dopant in polyaniline, water resistance is improved as compared to polyaniline having a sulfonic acid which is a low molecular compound as a dopant (see Patent Document 3), but still sufficient. However, for example, even if polyvinyl sulfonic acid, which is a polymer sulfonic acid, is added to polyaniline as a dopant, a decrease in conductivity is inevitable if immersed in water for a long period of time.

In order to further improve the water resistance of the conductive polyaniline composition, it is useful to have polyaniline as a polymer dopant with a novolak resin having a sulfonic acid group such as a phenolsulfonic acid novolak resin or a naphtholsulfonic acid novolak resin. As already found, the water resistance is still insufficient depending on the application.
Japanese Patent Laid-Open No. 03-035516 JP 10-36667 A Japanese Patent Laid-Open No. 03-28229 JP 2002-275261 A JP 2004-27066 A

  Therefore, as a result of intensive studies to further improve the water resistance of the conductive polyaniline composition, the present inventor has made a water-insoluble conductive polymer by crosslinking a phenol sulfonic acid novolak resin or a naphthol sulfonic acid novolak resin as a dopant. The present inventors have found that a functional polyaniline composition can be obtained, and have reached the present invention.

  That is, an object of the present invention is to provide a water-insoluble conductive polyaniline composition and a method for producing the same, and further to provide a film comprising the water-insoluble conductive polyaniline composition.

  According to the present invention, there is provided a water-insoluble conductive polyaniline composition characterized in that polyaniline has at least one selected from a crosslinked phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin as a dopant. Is done.

  Here, preferably, the cross-linked phenolsulfonic acid novolak resin or naphtholsulfonic acid novolak resin is cross-linked with a polyfunctional isocyanate compound or a polyfunctional epoxy compound.

  Moreover, according to this invention, the film which consists of said water-insoluble electroconductive polyaniline composition is provided.

  Furthermore, according to the present invention, an aqueous solution comprising a water-soluble conductive polyaniline composition having at least one water-soluble resin selected from a phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin as a dopant and a polyfunctional crosslinking agent. There is provided a method for producing the water-insoluble conductive polyaniline composition, which comprises coating the substrate on a substrate, heating, and crosslinking the resin.

  In such a method for producing a water-insoluble conductive polyaniline composition, the water-soluble conductive polyaniline composition is at least one water-soluble compound selected from phenolsulfonic acid novolak resin and naphtholsulfonic acid novolak resin with respect to aniline. It can be obtained by chemical oxidative polymerization of aniline with an oxidizing agent in water in the presence of at least an equivalent amount of resin.

  The conductive polyaniline composition according to the present invention is insoluble in water, has excellent water resistance, and also has excellent heat resistance. Therefore, in a wide range of industrial fields, antistatic, anticorrosion, electric field capacitor solid electrolyte, electroluminescence It can be used as a conductive film having practical durability for various uses such as an electrode buffer layer and a battery.

  The water-insoluble conductive polyaniline composition according to the present invention has at least one selected from a crosslinked phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin as a dopant, and the crosslinked phenolsulfonic acid The novolak resin or naphtholsulfonic acid novolak resin is preferably obtained by crosslinking at least one selected from a phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin with a polyfunctional isocyanate compound or a polyfunctional epoxy compound as a crosslinking agent. It is. Such a water-insoluble conductive polyaniline composition according to the present invention is mainly used as a film.

  The production of the water-insoluble conductive polyaniline composition according to the present invention will be described. The water-insoluble conductive polyaniline composition according to the present invention is firstly prepared in the presence of at least an equivalent equivalent of at least one water-soluble resin selected from phenolsulfonic acid novolak resin and naphtholsulfonic acid novolak resin with respect to aniline. Then, an aqueous solution of a water-soluble conductive polyaniline composition having the above resin as a dopant is obtained by chemical oxidative polymerization of aniline with an oxidizing agent, and then the water-soluble conductive polyaniline composition thus obtained is obtained. A water-insoluble conductive polyaniline having the cross-linked resin as a dopant by adding a polyfunctional cross-linking agent to an aqueous solution, applying this onto a suitable substrate, heating, and cross-linking the resin with the cross-linking agent. The composition can be obtained as a film. However, the above “equivalent” means that in an acid-base reaction, the number of equivalents of sulfonic acid groups possessed by the novolak resin is equal to the number of equivalents of amino groups possessed by aniline.

  The water-soluble conductive polyaniline composition contains aniline as an oxidizing agent in water in the presence of at least an equivalent equivalent of at least one water-soluble resin selected from phenolsulfonic acid novolak resin and naphtholsulfonic acid novolak resin. It can be obtained as an aqueous solution by chemical oxidative polymerization.

  In the present invention, the chemical oxidative polymerization aniline includes alkyl anilines such as methyl aniline and ethyl aniline, alkoxy anilines such as methoxy aniline and ethoxy aniline, and salts thereof such as sulfates. I will do it.

  In addition, as described in Japanese Patent No. 2844335, the oxidant has a standard electrode potential determined as an electromotive force in a reduction half-cell reaction based on a standard hydrogen electrode of 0.6 V or more, and water. If it is soluble in water, it is necessary to use an oxidizing agent that is neutral and that does not generate anionic species after it has been reduced. Therefore, according to the present invention, for example, hydrogen peroxide, permanganates, dichromates, manganese dioxide, lead dioxide or the like is preferably used as an oxidizing agent that does not generate anionic species after itself is reduced. .

  When an aniline is oxidatively polymerized using an oxidizing agent that generates an anionic species when it is reduced, the polyaniline that can also obtain an anionic species derived from such an oxidizing agent has a dopant. The water solubility of the polyaniline obtained may be impaired, and the water resistance and heat resistance may be impaired.

  According to the present invention, the oxidizing agent as described above is usually used in an equivalent amount with respect to aniline. When the oxidizing agent is used in excess of an equivalent amount relative to aniline, the oxidizing agent remains excessively in the reaction system after polymerization, so that the resulting conductive polyaniline composition may be deteriorated in its electrical properties. According to the present invention, a redox oxidant is also preferably used as the oxidant. The redox oxidant is composed of a combination of two components, an oxidant and a small amount of a reducing agent, and a combination of hydrogen peroxide and ferrous sulfate is well known as a Fenton reagent.

  Thus, only the novolac resin is obtained by oxidatively polymerizing aniline with the oxidizing agent in water in the presence of at least one water-soluble resin selected from a phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin. A water-soluble conductive polyaniline composition having as a dopant can be obtained.

  Thus, a water-soluble conductive polyaniline composition obtained by oxidative polymerization of aniline with an oxidizing agent in the presence of a water-soluble novolak resin such as a phenolsulfonic acid novolak resin or a naphtholsulfonic acid novolak resin, As described in Japanese Laid-Open Patent Publication No. 03-028229, Japanese Patent No. 2909544, Japanese Patent Laid-Open No. 2002-275261, Japanese Patent Laid-Open No. 2004-027067, etc., the general formula (I)

(In the formula, m and n respectively represent the molar fractions of the quinonediimine structural unit and the phenylenediamine structural unit in the repeating unit, and 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, and m + n = 1.)
The polyaniline represented by the above formula has the above-described phenolsulfonic acid novolak resin or naphtholsulfonic acid novolak resin as a dopant.

  The phenolsulfonic acid novolak resin or naphtholsulfonic acid novolak resin used in the present invention is preferably represented by the general formula (II)

(In the formula, Ar represents a (4 + n) -valent aromatic group, and in the case of a phenolsulfonic acid novolak resin, it is a benzene nucleus (where n is 1 or 2), and in the case of a naphtholsulfonic acid novolak resin. A naphthalene nucleus (where n is 1, 2, 3 or 4), R represents a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, a carboxyl group or an amino group, and when n is 2 or more, Same or different.)
It has a repeating unit represented by .

  In the present invention, as the phenolsulfonic acid novolak resin or naphtholsulfonic acid novolak resin, for example, a resin represented by the above general formula (II) in which R is a hydrogen atom is preferably used. Such a phenolsulfonic acid novolak resin or a naphtholsulfonic acid novolak resin can be obtained as a developed product (Konishi Chemical Co., Ltd.).

  The molecular weight of such a phenol sulfonic acid novolak resin or naphthol sulfonic acid novolak resin is not particularly limited, but usually the weight average molecular weight measured by GPC using polystyrene sulfonic acid as a standard polymer is in the range of 2,000 to 800,000. It is desirable. When the molecular weight of the phenol sulfonic acid novolak resin or the naphthol sulfonic acid novolak resin is too low, the water resistance of the resulting conductive polyaniline composition may not be sufficient even when these crosslinked resins are used as a dopant. On the other hand, when the molecular weight of the phenolsulfonic acid novolak resin or naphtholsulfonic acid novolak resin is too high, when it is dissolved in water, the viscosity of the aqueous solution is too high and it is difficult to stir uniformly. Therefore, in such an aqueous solution of novolak resin, it is difficult to uniformly oxidize and polymerize aniline.

  Next, a polyfunctional crosslinking agent is added to the aqueous solution of such a water-soluble conductive polyaniline composition, and the resulting solution is applied onto an appropriate substrate, heated, and the resin is coated with the polyfunctional crosslinking agent. By crosslinking, as a dopant, it has at least one selected from a crosslinked phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin, and thus a film made of a water-insoluble conductive polyaniline composition can be obtained. That is, according to the present invention, at least one selected from a phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin that polyaniline has as a dopant is crosslinked by reacting the phenolic hydroxyl group that it has with a crosslinking agent, A water-insoluble conductive polyaniline composition is obtained.

  Accordingly, in the present invention, a polyfunctional isocyanate compound or a polyfunctional epoxy compound is preferably used as the crosslinking agent. However, when the polyfunctional isocyanate compound is added as it is to the aqueous solution of the water-soluble conductive polyaniline composition, it easily reacts with water and does not act as a crosslinking agent. A water-dispersed type that is a polyisocyanate for paints that can be used, and a blocked polyisocyanate in which an isocyanate group is blocked with a blocking agent such as oximes are preferably used.

  As already known, the blocked polyisocyanate has an isocyanate group protected by the blocking agent in the isocyanate compound, so it does not react with water even in water. However, when heated, the blocking agent is released from the isocyanate group. Release the isocyanate group to act as an isocyanate compound.

  Examples of the water-dispersed polyisocyanates include “Aquanate” manufactured by Nippon Polyurethane Industry Co., Ltd., and examples of the block polyisocyanate include “AQB” manufactured by Nippon Polyurethane Industry Co., Ltd. Etc. can be illustrated.

  Examples of the polyfunctional epoxy compound include “Epicoat” manufactured by Mitsubishi Chemical Corporation and “Novolac type epoxy resin” manufactured by Sumitomo Chemical Co., Ltd.

  According to the present invention, these polyfunctional crosslinking agents are usually used in an amount of 0.5 to 100 parts by weight based on at least one kind selected from a phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin that polyaniline has as a dopant. It is used in the range of 30 parts by weight, preferably in the range of 2 to 10 parts by weight.

  An aqueous solution containing a water-soluble conductive polyaniline composition and a polyfunctional crosslinking agent is applied onto an appropriate substrate such as a glass plate, a plastic plate, a plastic film, a metal plate, a metal foil, or a ceramic, and heated to heat the resin. By crosslinking with a polyfunctional crosslinking agent, a film comprising a water-insoluble conductive polyaniline composition having a crosslinked phenolsulfonic acid novolak resin or naphtholsulfonic acid novolak resin as a dopant can be obtained.

  Here, the heating temperature is usually in the range of 70 to 200 ° C. so that water is evaporated from the aqueous solution applied on the substrate and the crosslinking agent sufficiently reacts with the phenolic hydroxyl group of the resin. What is necessary is just to heat, Preferably, what is necessary is just to heat to the temperature of the range of 100-150 degreeC. The heating time can be appropriately determined by experiment, but is usually in the range of 1 minute to 24 hours, and preferably in the range of about 5 minutes to 2 hours.

  The water-insoluble conductive polyaniline composition according to the present invention thus obtained is a polyfunctional cross-linked at least one selected from a phenol sulfonic acid novolak resin and a naphthol sulfonic acid novolak resin which polyaniline has as a dopant. It reacts with the agent to have a crosslinked structure. That is, the dopant that the water-insoluble conductive polyaniline composition according to the present invention has is represented by the general formula (III) as the polyfunctional crosslinking agent.

(In the formula, Z represents a divalent organic group.)
For example, when using a diisocyanate represented by

It can be expressed as Here, the polymer chain represents at least one selected from a phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin which are polyaniline dopants. That is, at least one selected from a phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin, which are dopants of polyaniline, is crosslinked by a crosslinking agent to form a water-insoluble conductive polyaniline composition.

According to the present invention, a film made of a water-insoluble conductive polyaniline composition having an electrical conductivity of about 10 ⁻² to 10 ² S / cm can be obtained in this manner. In the conductive polyaniline film according to the present invention thus obtained, the polymer dopant has a crosslinked structure, and therefore does not dissolve even when the film is immersed in water. For example, even if such a conductive film according to the present invention is immersed in water for 500 hours, the decrease in conductivity is within one digit. In addition, the conductive film according to the present invention is excellent in heat resistance. For example, even after heating at 125 ° C. for 500 hours, the decrease in conductivity is similarly within one digit.

  Therefore, the water-insoluble conductive polyaniline composition according to the present invention is a practical and durable conductive film for various uses such as antistatic, anticorrosion, electrolytic capacitor solid electrolyte, electroluminescence electrode buffer layer, battery and the like. Can be used.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1
A phenolsulfonic acid novolak resin aqueous solution (manufactured by Konishi Chemical Industries, Ltd., weight average molecular weight 20000 by polystyrene sulfonic acid standard GPC) was adjusted to a solid content concentration of 33% by weight. 180 g of this aqueous solution was placed in a 300 mL separable flask equipped with a stirrer, a thermometer and a straight tube adapter, and 8.5 g of aniline was further added and stirred and dissolved to obtain a uniform aqueous solution. The whole flask was cooled to −5 ° C. using a low-temperature thermostatic bath, and 50 mg of ferrous sulfate was added thereto and dissolved by stirring.

  Next, 12.9 g of 30% hydrogen peroxide solution was added to 64.5 g of ion-exchanged water in a beaker and dissolved by stirring to obtain a colorless and transparent uniform aqueous solution. This aqueous hydrogen peroxide solution was gradually dropped into the above separable flask at a rate of 1 mL / min or less from a straight tube adapter using a tubing pump while stirring. At this time, the dropping rate was appropriately adjusted so as to keep the temperature of the reaction system at −3 ° C. or lower.

  The aqueous solution in the flask was initially colorless and transparent, but turned from greenish blue to blackish green as aniline polymerization proceeded. However, no precipitate of polyaniline was formed in the aqueous solution, and the aqueous solution remained uniform. Thus, after dripping the hydrogen peroxide aqueous solution over 1 hour, stirring was further continued for 30 minutes while keeping the temperature of the reaction system at −3 ° C. or lower.

  After returning the polyaniline aqueous solution thus obtained to room temperature, 13.8 g of an aqueous block polyisocyanate (AQB-102 manufactured by Nippon Polyurethane Industry Co., Ltd.) is added as a cross-linking agent to the aqueous solution. Stir until.

  Next, four banks of 120 μm thick resin tape are stacked on both sides of the glass plate to form a bank, and an aqueous polyaniline solution in which the cross-linking agent is dissolved is cast between the banks, and after squeezing with a glass rod, drying is performed. In the machine, it was dried at 80 ° C. for 30 minutes to evaporate water. Furthermore, the dryer temperature was raised to 150 ° C., and subsequently, the phenolsulfonic acid novolak resin was crosslinked with isocyanate.

  The black-green polyaniline film thus obtained was peeled off from the glass plate, a part was cut out, and the conductivity was measured by the four-terminal method by van der Pauw method. It was 8.7 S / cm. A part of the obtained polyaniline film was cut out and immersed in water, but the polyaniline film did not dissolve at all.

  Therefore, after the polyaniline film was immersed in water for 500 hours, taken out, dried, and again measured for conductivity by the van der Pou method, the conductivity was 7.7 S / cm. The decrease was very small compared to before immersing for 500 hours. Furthermore, when the polyaniline film separated from the glass plate was placed in a dryer at a temperature of 125 ° C. for 500 hours and then subjected to 4-terminal conductivity measurement, the conductivity was 6.25 S / cm. That is, the polyaniline film was excellent in heat resistance.

Comparative Example 1
In Example 1, after obtaining a polyaniline aqueous solution, a polyaniline film was prepared on a glass plate in the same manner as in Example 1 except that no crosslinking agent was added thereto. The obtained polyaniline film had a conductivity of 9.3 S / cm, almost the same as the polyaniline film according to Example 1.

  However, when a part of this film was immersed in water, the shape of the film gradually collapsed and finally dissolved in water. Further, the electrical conductivity after the polyaniline film was placed in a drier at a temperature of 125 ° C. for 500 hours had an electrical conductivity of 6.9 S / cm, almost the same as the polyaniline film according to Example 1. When a part of the film was immersed in water, the shape gradually collapsed and finally dissolved in water.

Claims (4)

A water-insoluble conductive polyaniline composition comprising polyaniline as a dopant, at least one selected from a phenolsulfonic acid novolak resin and a naphtholsulfonic acid novolak resin each crosslinked with a polyfunctional isocyanate compound . A film comprising the water-insoluble conductive polyaniline composition according to claim 1 . A water-soluble conductive polyaniline composition having at least one water-soluble resin selected from a phenol sulfonic acid novolak resin and a naphthol sulfonic acid novolak resin as a dopant and an aqueous solution containing a polyfunctional isocyanate compound as a crosslinking agent are coated on a substrate. The method for producing a water-insoluble conductive polyaniline composition according to claim 1, wherein the resin is crosslinked by heating. In the presence of at least an equivalent equivalent of at least one water-soluble resin selected from phenolsulfonic acid novolak resin and naphtholsulfonic acid novolak resin with respect to aniline, aniline is chemically oxidatively polymerized with an oxidizing agent in water, The method for producing a water-insoluble conductive polyaniline composition according to claim 3 , wherein a water-soluble conductive polyaniline composition is obtained.