JP2636793B2 - Conductive polymer compound and solid electrolytic capacitor using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be widely used for various electronic parts, electrodes, etc., and is a stable conductive polymer compound which is hard to be dedoped even in water or under high temperature and high humidity. The present invention relates to a solid electrolytic capacitor having excellent resistance and moisture resistance.

[0002]

2. Description of the Related Art In recent years, remarkable technological advances have been made in the field of functional organic materials, and even in the field of conductive polymers, electronic conjugated polymers such as polyacetylene, polyparaphenylene, polypyrrole, polythiophene, and polyaniline have been developed. A conductive polymer material to which a donating or electron-accepting compound is added as a dopant has been developed and has been put to practical use as an electrode material or a conductive thin film. Among these conductive polymers, it is known that polyaniline and polypyrrole have high conductivity and are superior in stability in air as compared with other conductive polymers.

In general, the properties of conductive polymers such as polyaniline and polypyrrole change depending on the type of dopant and its content (dopant concentration). Therefore, various dopants have been studied for the purpose of applying conductive polymers to electronic devices. For example, JP-A-3-6245
No. 1 discloses benzenesulfonic acid, p-toluenesulfonic acid, benzenesulfonyl chloride, dodecylbenzenesulfonic acid, polyvinylsulfonic acid, methanesulfonic acid,
1-butanesulfonic acid, modified Nafion, 2,3
An electrode made of polyaniline using 5-trichlorobenzenesulfonic acid and biphenylsulfonic acid as dopants is disclosed.

On the other hand, a solid electrolytic capacitor uses, as a first electrode (anode), a porous formed body of a film-forming metal such as tantalum or aluminum, a surface oxide film as a dielectric, and manganese dioxide, 7, 7, 8, or It has a structure in which an 8-tetracyanoquinodimethane complex salt, a conductive polymer, or the like is used as a second electrode (cathode), that is, a solid electrolyte. Among them, the conductivity of the solid electrolyte depends on the internal resistance and leakage current of the capacitor,
In order to greatly affect the loss and the like in a high frequency region, development of a capacitor using a conductive polymer, which is a highly conductive material, as an electrolyte is in progress.

For example, Japanese Patent Publication No. 4-56445 discloses a solid electrolytic capacitor using doped polypyrrole or an alkyl-substituted product thereof as an electrolyte. The electrolytic polymerization of pyrrole and the polypyrrole of metal on which a dielectric film is formed are disclosed. A method for forming an electrolyte by immersion in a solution is described. Further, Japanese Patent Application Laid-Open No. 62-29124 discloses a solid electrolytic capacitor using polyaniline as an electrolyte with arylsulfonic acid as a dopant.

[0006]

However, these publications on solid electrolytic capacitors include methods and dopants for improving stability under high temperature and water vapor atmosphere which are important in using polypyrrole and polyaniline for electronic devices. There is no description of the conditions. For this reason, conductive polymers are expected as materials for various electronic components and electrodes, but there are few stable conductive polymer compounds that are highly conductive and hard to dedope even in water or under high temperature and high humidity. There is a problem that it is difficult to obtain a solid electrolytic capacitor having a low internal resistance using a stable conductive polymer and having excellent heat resistance and moisture resistance.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a stable conductive polymer compound which is hardly dedoped even in water or under high temperature and high humidity, and a solid electrolytic capacitor using the same which has low internal resistance and excellent heat resistance and moisture resistance. Is to provide.

[0008]

Means for Solving the Problems The present inventors have conducted various studies to solve the above-mentioned problems. As a result, the conductive polymer compound, which is characterized by containing a sulfonated product of a methylolated melamine compound, is excellent in stability because it is hardly dedoped even in water or under high temperature and high humidity with high conductivity, and It has been found that a solid electrolytic capacitor using a conductive polymer containing a sulfonated melamine compound of methylol as an electrolyte has low internal resistance and excellent heat resistance and moisture resistance. That is, the conductive polymer compound of the present invention is characterized by containing a sulfonated product of a methylolated melamine compound. Further, the solid electrolytic capacitor of the present invention is characterized in that a conductive polymer containing a sulfonate of a melamine compound converted into a methylol is used as an electrolyte.

As shown in FIG. 1, the methylolated melamine compound in the present invention is obtained by converting a melamine skeleton, that is, a compound having a 2,4,6-triamino-1,3,5-triazine skeleton, into methylol. A compound in which three amino groups have been replaced by 1 to 6 hydroxymethyl groups. The sulfonated product is a compound in which a part or all of the hydroxymethyl group of a methylolated melamine compound is sulfonated to be a sulfomethyl group. These compounds include 2
-Hydroxymethylsulfomethylamino-4,6-diamino-1,3,5-triazine, 2,4-bis (hydroxymethylsulfomethylamino) -6-amino-1,
3,5-triazine, 2,4,6-tris (hydroxymethylsulfomethylamino) -1,3,5-triazine, 2-hydroxymethylsulfomethylamino-4,6
-Bis (dihydroxymethylamino) -1,3,5-triazine, 2,4-bis (hydroxymethylsulfomethylamino) -6-dihydroxymethylamino-1,3
5-triazine and the like. In the present invention, a mixture of two or more sulfonated melamine compounds methylolated can be used.

In the present invention, the method for synthesizing the sulfonated product of a methylolated melamine compound is not particularly limited. For example, a method of reacting melamine and formaldehyde in an aqueous solution to form methylol and then sulfonating with pyrosulfite is used. No. In this reaction, the ratio of the hydroxymethyl group to be introduced is determined by the number of moles of formaldehyde to melamine, and the ratio of the sulfomethyl group to be introduced is further determined by the number of moles of pyrosulfite.

The conductive polymer containing a sulfonated methylolated melamine compound of the present invention is a conjugated polymer compound containing the above sulfonated methylolated melamine compound as a dopant, for example, polypyrrole, polyaniline, polythiophene. , Polyfuran, polyparaphenylene, polyacetylene, polyparaphenylenevinylene, polyazulene, and derivatives thereof, and polypyrrole and polyaniline are particularly preferable from the viewpoint of high conductivity.

In the present invention, the method for producing these conductive polymers is not particularly limited. For example, compounds that can become conductive polymers in an electrolytic solution containing a sulfonate of a methylolated melamine compound or a salt thereof. In an acid solution obtained by electrolytic polymerization of a melamine compound converted into methylol and sulfonation of a methylolated melamine compound, a compound that can be a conductive polymer is oxidized and polymerized using an oxidizing agent, or a previously prepared conductive polymer is removed. After doping, it is produced by doping again with a sulfonate of a methylolated melamine compound.

As shown in FIG. 2, for example, the solid electrolytic capacitor of the present invention uses a film-forming metal 1 such as tantalum or aluminum as an anode and a surface oxide film 2 of the film-forming metal 1.
Is a capacitor electrically connected to the cathode 4 using the conductive polymer 3 as an electrolyte and the conductive polymer 3 as an electrolyte, wherein the conductive polymer contains a sulfonated melamine compound converted into methylol.

In the solid electrolytic capacitor of the present invention, the kind of the film-forming metal 2 is not limited, and a conventionally known base metal of the electrolytic capacitor such as tantalum or aluminum can be used. The shape and the method of forming the dielectric film 2 are not particularly limited, and a conventionally known material such as a fine powder sintered pellet or a rolled foil etched by an anodizing method or the like in an electrolytic solution may be used. It is used after forming a body metal oxide film.

In the solid electrolytic capacitor of the present invention, the method for producing the conductive polymer 3 as an electrolyte is not particularly limited.
As a method for forming the conductive polymer, a conventionally known method is used. These methods include, for example, a method of growing a conductive polymer from an electrode for polymerization by an electrolytic polymerization method, a method of introducing a reaction solution for forming a conductive polymer on a dielectric surface, and a method of conducting a conductive polymer. And the like. In the present invention, the conductive polymer having another synthesized dopant may be dedoped in advance, and then re-doped with a methylolated sulfonated melamine compound.

[0016]

The sulfonated methylolated melamine compound which is a dopant of the conductive polymer of the present invention has a melamine skeleton excellent in heat resistance and contains many polar groups such as hydroxymethyl group and sulfomethyl group. Therefore, the interaction with the conductive polymer is strong. Therefore, the conductive polymer of the present invention is hardly dedoped even in water or under high temperature and high humidity, and has excellent stability.

Further, the electrolytic capacitor of the present invention has excellent stability because the conductive polymer as the electrolyte is highly conductive and is hardly dedoped even in water or under high temperature and high humidity. Excellent in moisture resistance. Also, the solid electrolytic capacitor of the present invention is completed as a capacitor, by using a conductive paste such as carbon paste or silver paste to draw out lead electrodes and sealing it with a resin or metal case as in the case of a normal solid electrolytic capacitor.

[0018]

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

Example 1 37 wt. 146 g of a 1% aqueous formaldehyde solution was placed in each of three glass reaction vessels, and 75.6 g of melamine was added to each vessel, and the mixture was heated to 80 ° C. with stirring to obtain a transparent solution.
As a result of infrared absorption spectrum measurement, this solution was 2,4,6-
Tris (dihydroxymethylamino) -1,3,5-triazine. The solution was cooled to 40 ° C. while stirring and 19 g, 38 g, and 57 g of sodium pyrosulfite were added.
g was added to each reaction vessel and then 83 g of water was added dropwise. Furthermore, p of the mixed solution is
H was adjusted to 10.5, heated at 80 ° C. for 90 minutes, and cooled to room temperature, whereupon each was 2-sulfomethylhydroxymethylamino-4,6-bis (dihydroxymethylamino) -1,3,5-triazine. Aqueous solution, 2,4-bis (sulfomethylhydroxymethylamino) -6-dihydroxymethylamino-1,3,5-triazine aqueous solution,
And an aqueous solution of 2,4,6-tris (sulfomethylhydroxymethylamino) -1,3,5-triazine.

Next, the resulting solution was passed through an ion-exchange resin (Duolite C-20, manufactured by Wako Pure Chemical Industries, Ltd.) column to obtain three types of aqueous solutions containing sulfonic acid of a methylolated melamine compound. 10 g of these aqueous solutions were added to 0.1 g.
Neutralization titration with 1N aqueous sodium hydroxide
Acid solutions of 0.18N, 0.35N, and 0.53N, respectively. From the result and the concentration of each solution, the number of sulfonic acid groups per molecule of the sulfonated product of the methylolated melamine compound contained was 1, 2, and 3, respectively.
It turned out to be.

Next, 3-sulfomethylhydroxymethylamino-4,6-bis (dihydroxymethylamino) -1,3,5-triazine, 2,4-
Bis (sulfomethylhydroxymethylamino) -6-dihydroxymethylamino-1,3,5-triazine and 2,4,6-tris (sulfomethylhydroxymethylamino) -1,3,5-triazine were sequentially 33 mmol.
A sulfonated solution of a melamine compound methylolated so as to be 1, 22, and 11 mmol was added thereto, and the mixture was stirred at 0 ° C. with 40 ml of water and 1.023 g of aniline. Add ammonium dichromate 0.8 to these solutions.
8 g and 24 mmol of 2-sulfomethylhydroxymethylamino-4,6-bis (dihydroxymethylamino)
-1,3,5-triazine, 2,4-bis (sulfomethylhydroxymethylamino) -6-dihydroxymethylamino-1,3,5-triazine, and 2,4,6-
Tris (sulfomethylhydroxymethylamino) -1,
Three kinds of aqueous solutions containing 3,5-triazine were added dropwise at 0 ° C.
For 2 hours.

As a result, a dark green reaction product is obtained,
After washing and drying, 2-sulfomethylhydroxymethylamino-4,6-bis (dihydroxymethylamino) -1,3,5-triazine, 2,4-bis (sulfomethylhydroxymethylamino) -6-dihydroxymethylamino -1,3,5-triazine, and 2,4
6-tris (sulfomethylhydroxymethylamino)-
Three types of polyaniline powders using 1,3,5-triazine as a dopant were obtained. These polyaniline powders are pressed and molded to a length of 10 mm, a width of 1.5 mm and a thickness of 0.1 mm.
mm, the conductivity was measured by a four-terminal method, and the results were 1.0 S / cm, 1.1 S / cm, and 1. S / cm, respectively.
It was 5 S / cm, and could be used as a conductive material for various electronic components and electrodes. In addition, the thermogravimetric analysis showed that all of them were excellent in heat resistance without a thermogravimetric change up to 300 ° C.

Example 2 5 g of a powder of polypyrrole (dopant concentration: 25 mol% based on monomer unit, conductivity: 30 S / cm) using p-toluenesulfonic acid as a dopant was suspended in pure water in an argon gas atmosphere. . 25 wt. 20 g of aqueous ammonia was added dropwise and stirred for 2 hours, then filtered and washed. Next, 0.5 g of each of the obtained polypyrrole powders was used to prepare 2-sulfomethylhydroxymethylamino-
4,6-bis (dihydroxymethylamino) -1,3
5-triazine, 2,4-bis (sulfomethylhydroxymethylamino) -6-dihydroxymethylamino-
1,3,5-triazine and 2,4,6-tris (sulfomethylhydroxymethylamino) -1,3,5
-Poured in a triazine solution and stirred at room temperature for 12 hours to obtain a dark blue powder.

These powders contained S atoms as a result of elemental analysis, and contained 2-sulfomethylhydroxymethylamino-4,6-bis (dihydroxymethylamino) -1,
3,5-triazine, 2,4-bis (sulfomethylhydroxymethylamino) -6-dihydroxymethylamino-1,3,5-triazine, and 2,4,6-tris (sulfomethylhydroxymethylamino) -1 , 3,5
-It was considered that triazine was included as a dopant. When the conductivity of the obtained polypyrrole powder was measured by the method of Example 1, it was 12 S / cm and 18 respectively.
S / cm and 20 S / cm, various electronic components,
It could be used as a conductive material such as an electrode. In addition, the thermogravimetric analysis showed that all of them were excellent in heat resistance without a thermogravimetric change up to 300 ° C.

(Example 3) 2 m in diameter with anode lead
m, 2 mm high columnar tantalum fine powder sintered pellets are immersed in a 0.05 wt% phosphoric acid aqueous solution, anodized at 48 V with a stainless steel plate as a counter electrode, washed and dried to remove metal oxide film. A sintered tantalum pellet having a dielectric film was obtained. The pellet was immersed in a 0.1 N aqueous sulfuric acid solution, and the capacitance was measured.

Next, a concentration of 13 wt. % 2,4,6-tris (sulfomethylhydroxymethylamino) -1,3,5-triazine and 5 wt. % Of aniline was prepared, and the tantalum sintered body pellet was immersed and taken out. After 5 minutes, the pellets are
t. % Ammonium bichromate and 15 wt. % Of 2,
The polymer was immersed in an aqueous solution containing 4,6-tris (sulfomethylhydroxymethylamino) -1,3,5-triazine, taken out, and kept in the air for 20 minutes to polymerize aniline. Then, it was washed with water and methanol and dried at 80 ° C. When the above operation was repeated four times, a pellet whose dielectric surface was coated with polyaniline using 2,4,6-tris (sulfomethylhydroxymethylamino) -1,3,5-triazine as a dopant was obtained. .

A cathode lead was attached to the pellet using a silver paste to complete a capacitor. The resulting capacitor has a capacitance measured at 120 Hz of 10 μF, 100 μF.
The equivalent series resistance at kHz was 0.2Ω, and the capacitor had good properties with little change in capacitance up to the resonance frequency range. In addition, even in a solder bath immersion test at 260 ° C. for 25 seconds and a humidity resistance test at a relative humidity of 95% and 85 ° C. for 8 hours, the performance was not changed and the heat resistance was excellent.

(Embodiment 4) 10 mm.times.5 m at a thickness of 150 .mu.m whose surface area is enlarged almost 50 times by etching.
m of aluminum foil of 5 wt. Anodized at 100 V in an aqueous solution of ammonium borate at 100 V, washed and dried to obtain an aluminum foil having a dielectric film composed of a metal oxide film. This foil was immersed in a 0.1N sulfuric acid aqueous solution, and the capacitance was measured to be 1.5 μF.

A gold wire was brought into contact with the upper part of this aluminum foil, and the weight of 0.8 wt. % Pyrrole and 5 wt. % 2,4
6-tris (sulfomethylhydroxymethylamino)-
It was immersed once in an electrolytic polymerization solution consisting of an acetonitrile solution containing 1,3,5-triazine and pulled up, and a part of the lower portion was kept immersed in the solution. In this state, when a voltage of 7.8 V was applied between the gold wire and the nickel plate disposed below the aluminum foil as a cathode, polypyrrole grew immediately from the gold wire, and dendritic polypyrrole was formed on the aluminum foil surface. After about 6 minutes, the solution at the bottom of the foil was reached. Next, the whole including the gold wire was immersed in the electrolytic polymerization solution, and a voltage of 1.8 V was applied to react for 30 minutes. The obtained foil is immersed in methyl alcohol, washed, dried at 85 ° C., and the surface of the dielectric film is coated with 2,4,6-tris (sulfomethylhydroxymethylamino) -1,3,5-triazine as a dopant. Thus, pellets coated with polypyrrole were obtained.

A negative electrode lead was attached to the pellet using a silver paste to complete a capacitor. The resulting capacitor had a capacitance measured at 120 Hz of 1.2 μF,
The equivalent series resistance at 0 kHz was 0.1Ω, and the capacitor had good properties with little change in capacitance up to the resonance frequency range.
In addition, even in a solder bath immersion test at 260 ° C. for 25 seconds and a humidity resistance test at a relative humidity of 95% and 85 ° C. for 8 hours, the performance was not changed and the heat resistance was excellent.

[0031]

As described above, since the conductive polymer compound of the present invention contains a sulfonated product of a methylolated melamine compound, the conductive polymer compound is hardly dedoped even in water or under high temperature and high humidity, and has a stable conductive property. Since it can be configured as a polymer compound, it can be widely used for various electronic components and electrodes, and the reliability of such electronic components and electrodes can be improved.

Further, according to the present invention, by forming a solid electrolytic capacitor using a conductive polymer containing a sulfonated product of a methylolated melamine compound as an electrolyte or a cathode, the internal resistance is reduced and heat resistance and moisture resistance are reduced. An excellent solid electrolytic capacitor can be obtained.

[Brief description of the drawings]

FIG. 1 is a structural formula of a sulfonated product of a methylolated melamine compound according to the present invention.

FIG. 2 is a structural diagram of an example of a solid electrolytic capacitor according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 film forming metal (anode) 2 surface oxide film 3 conductive polymer 4 cathode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01B 1/16 H01B 1/16 A

Claims (5)

(57) [Claims] 1. A conductive polymer compound containing a sulfonated melamine compound methylolated. 2. The conductive polymer compound according to claim 1, wherein the conductive polymer compound is a conjugated polymer compound containing, as a dopant, a sulfonated product of a methylolated melamine compound. 3. The conductive polymer compound according to claim 2, wherein the conductive polymer compound is polyaniline, polypyrrole, or a derivative thereof. 4. A solid electrolytic capacitor using, as an electrolyte, a conductive polymer containing a sulfonated melamine compound methylolated. 5. The solid electrolytic capacitor according to claim 4, wherein the film-forming metal is an anode, the surface oxide film of the film-forming metal is a dielectric, and the conductive polymer provided on the dielectric is a cathode or an electrolyte.