JP2016171111A - Solid electrolytic capacitor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor that is highly flame retarded, and a method for manufacturing the same.SOLUTION: A solid electrolytic capacitor includes: an anode conductor 1; a dielectric layer 2 formed on the anode conductor; a solid electrolyte layer 3 formed on the dielectric layer; and a cathode layer formed on the solid electrolyte layer and comprising a graphite layer 4 and a silver layer 5. The solid electrolytic capacitor includes a layer containing dissolution precipitates of a non-halogen phosphazene compound 11, such as a cyclic phenoxyphosphazene compound, in a solid electrolyte or at an interface with the dielectric layer or the cathode layer which is in contact with the solid electrolyte.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same, and more particularly to a solid electrolytic capacitor excellent in flame retardancy and a method for manufacturing the same.

Conventionally, a solid electrolytic capacitor in which a dielectric film is formed on the surface of an anode conductor made of a valve metal and the dielectric film is coated with a solid electrolyte is known.
This solid electrolyte uses organic materials such as conductive polymers and easily combustible materials such as manganese dioxide. Therefore, it is necessary to make it flame retardant in order to improve reliability. It is necessary to add a flame retardant in and near the solid electrolyte.

  In a conventional solid electrolytic capacitor, a phosphoric acid ester or the like is added as a flame retardant to a mold resin or the like in order to enhance the flame retardant effect (Patent Document 1). However, phosphoric ester-based flame retardants have high hydrolyzability, so that they are decomposed by moisture and have a drawback that the flame retardant effect is reduced. For this reason, in particular, it was difficult to add to the solid electrolyte layer using water containing water during the manufacturing process.

  Patent Document 2 discloses a method of dispersing a hardly soluble flame retardant in water with a powdered flame retardant in a solid electrolyte. Also, when antimony trioxide is used as a flame retardant, a halogen-based flame retardant is mixed in the paste in the solid electrolyte layer, or in the silver paste or carbon paste in the current collector layer, or as a constituent material of these pastes. It is disclosed that a halogen-containing substance (halogenated substance) may be used.

JP 2005-93463 A JP 2009-224673 A

  The flame retardant used in Patent Document 2 is an inorganic flame retardant and has poor water solubility, so that it easily aggregates during formation of the solid electrolyte and tends to be non-uniform in dispersion state. If the dispersion of the flame retardant becomes non-uniform, the flame retardant effect may be reduced. Moreover, in the Example of patent document 1, the example which uses a flame retardant is not shown.

  An object of the present invention is to provide a solid electrolytic capacitor in which a flame retardant is uniformly added in a layered manner in or near a solid electrolyte.

  In the present invention, a non-halogen phosphazene compound having high water resistance that acts as a flame retardant is used, and this non-halogen phosphazene compound is dissolved in a solvent and added uniformly in a layered manner in or near the solid electrolyte.

That is, according to one aspect of the present invention,
A solid electrolytic capacitor comprising an anode conductor, a dielectric layer formed on the anode conductor, a solid electrolyte formed on the dielectric layer, and a cathode layer formed on the solid electrolyte,
Provided is a solid electrolytic capacitor having a layer containing a dissolved precipitate of a non-halogen phosphazene compound in the solid electrolyte or at an interface with another layer in contact with the solid electrolyte.
According to another aspect of the present invention, there is provided a method for producing the above-mentioned solid electrolytic capacitor, wherein the non-halogen phosphazene compound is dissolved in a solvent and added. Is done.

  In the present invention, a non-halogen phosphazene compound having high water resistance is added in a solid electrolyte or in the vicinity of the solid electrolyte in a solution state dissolved in a solvent. An electrolytic capacitor can be provided.

The typical sectional view showing the structure of the solid electrolytic capacitor concerning one embodiment of the present invention. The typical sectional view showing an example of the distribution state of a non-halogen system phosphazene compound. The typical sectional view showing an example of the distribution state of a non-halogen system phosphazene compound. The typical sectional view showing an example of the distribution state of a non-halogen system phosphazene compound. The typical sectional view showing an example of the distribution state of a non-halogen system phosphazene compound.

Hereinafter, embodiments of the present invention will be described in detail.
[Solid electrolytic capacitor]
FIG. 1 is a schematic cross-sectional view showing the structure of the solid electrolytic capacitor according to the present embodiment. This electrolytic capacitor has a structure in which a dielectric layer 2, a solid electrolyte layer 3, a graphite layer 4 and a silver layer 5 are formed in this order on an anode conductor 1. The graphite layer 4 and the silver layer 5 on the outer periphery of the electrolyte layer 3 constitute a cathode layer, and are further connected to an electrode 7 serving as a connection terminal to the outside through a conductive adhesive 6. Further, a metal lead 8 made of a valve metal similar to that of the anode conductor 1 is provided on the surface of the anode conductor 1 where the solid electrolyte layer 3 is not formed. The metal lead 8 is a connection terminal different from the cathode layer. The electrode 7 is connected. Further, the whole is covered with an insulating exterior resin 9 such as an epoxy resin, and a solid electrolytic capacitor 10 is formed.

(Anode conductor)
The anode conductor 1 is formed of a valve metal plate, foil, or wire; a sintered body made of fine particles of the valve metal; a porous metal that has been subjected to surface expansion treatment by etching. Examples of the valve action metal include tantalum, aluminum, titanium, niobium, zirconium, and alloys thereof. Among these, at least one valve action metal selected from aluminum, tantalum and niobium is preferable. The metal lead 8 is preferably formed integrally with the anode conductor 1.

(Dielectric layer)
The dielectric layer 2 is a layer (also referred to as an oxide film) that can be formed by electrolytic oxidation of the surface of the anode conductor 1, and is also formed in a pore portion such as a sintered body or a porous body. The thickness of the dielectric layer 2 can be adjusted as appropriate by the voltage of electrolytic oxidation.

(Solid electrolyte layer)
The solid electrolyte layer 3 includes a conductive polymer obtained by polymerizing pyrrole, thiophene, aniline or a derivative thereof; an oxide derivative such as manganese dioxide or ruthenium oxide; TCNQ (7,7,8,8-tetracyanoquino) Organic semiconductors such as dimethane complex salts) can be used.
As a method for forming the solid electrolyte layer 3, for example, when the solid electrolyte is a conductive polymer, a suspension of the above-described conductive polymer is applied on the dielectric layer 2, or a dielectric is applied to the suspension. A method of immersing the anode conductor 1 (hereinafter also referred to as anode pellet) on which the body layer 2 is formed and removing the solvent from the suspension is exemplified.

  The solid electrolyte layer 3 may have a single layer structure or a multilayer structure. In the solid electrolytic capacitor 10 shown in FIG. 1, the solid electrolyte layer 3 has a two-layer structure, for example, a first conductive polymer layer 3A and a second conductive polymer layer 3B. The first conductive polymer layer 3A is also formed in the above-described pores by chemical oxidation polymerization or electrolytic polymerization, and the second conductive polymer layer 3B is formed by a coating method or a dipping method (dipping method). can do. The first conductive polymer contained in the first conductive polymer layer 3A and the second conductive polymer contained in the second conductive polymer layer 3B are the same type of polymer. Is preferred.

  As a monomer that provides a conductive polymer in chemical oxidative polymerization or electrolytic polymerization, at least one selected from pyrrole, thiophene, aniline, and derivatives thereof can be used. As a dopant used when this monomer is chemically oxidatively polymerized or electropolymerized to obtain a conductive polymer, sulfonic acid compounds such as benzenesulfonic acid, naphthalenesulfonic acid, phenolsulfonic acid, styrenesulfonic acid and derivatives thereof are used. preferable. The molecular weight of the dopant can be appropriately selected from low molecular weight compounds to high molecular weight compounds. In chemical oxidative polymerization or electrolytic polymerization, the monomer is dissolved or suspended in a solvent. This solvent may be water alone or a mixed solvent containing water and an organic solvent soluble in water.

At the time of coating or dipping, the above monomer is separately made into a conductive polymer by chemical oxidative polymerization or electrolytic polymerization, and then the conductive polymer is dispersed in water to prepare a suspension. The method of coating or dipping is not particularly limited, but it is preferable to leave it for several minutes to several tens of minutes after coating or dipping in order to sufficiently fill the porous polymer pores with the conductive polymer suspension. Moreover, it is preferable to perform pressure reduction or pressurization at the time of repetition of application or immersion, or application or immersion.
Removal of the solvent from the conductive polymer suspension can be performed by drying. The drying temperature is not particularly limited as long as the solvent can be removed, but the upper limit temperature is preferably less than 300 ° C. from the viewpoint of preventing conductive polymer deterioration due to heat. The drying time must be appropriately optimized depending on the drying temperature, but is not particularly limited as long as the conductivity is not impaired.

  As a method for forming the solid electrolyte layer 3, for example, when the solid electrolyte is manganese dioxide, a manganese nitrate solution is applied on the dielectric layer 2, or an anode conductor having a dielectric layer formed on the manganese nitrate solution is immersed. Thereafter, manganese nitrate is thermally decomposed to form a solid electrolyte layer made of manganese dioxide. As manganese nitrate, hydrates such as manganese nitrate (II) hexahydrate are preferably used. Manganese (II) nitrate hexahydrate is readily soluble in water and ethanol, and these solvents are used alone or in combination with other solvents. Although there is no restriction | limiting in particular in the thermal decomposition temperature, It can implement at the temperature of about 200-250 degreeC.

  The solid electrolyte according to the present invention is not particularly limited, but manganese dioxide and a conductive polymer are preferable from the viewpoint of conductivity, and a conductive polymer is particularly preferable.

Examples of the conductive polymer that forms the solid electrolyte layer include polypyrrole, polythiophene, polyaniline, and derivatives thereof. Among these, poly (3,4-ethylenedioxythiophene) or a derivative thereof is preferable. The conductive polymer may be a homopolymer, a copolymer, one type, or two or more types.
In the case of using a conductive polymer, it is preferable to combine a dopant that imparts high conductivity to the conductive polymer. Examples of the dopant include alkyl sulfonic acid, benzene sulfonic acid, naphthalene sulfonic acid, anthraquinone sulfonic acid, camphor sulfonic acid, polyacrylic acid, polystyrene sulfonic acid, and derivatives thereof. These sulfonic acids may be monosulfonic acid, disulfonic acid or trisulfonic acid. Examples of alkylsulfonic acid derivatives include 2-acrylamido-2-methylpropanesulfonic acid. Examples of benzenesulfonic acid derivatives include phenolsulfonic acid, styrenesulfonic acid, toluenesulfonic acid, and dodecylbenzenesulfonic acid. Examples of naphthalene sulfonic acid derivatives include 1-naphthalene sulfonic acid, 2-naphthalene sulfonic acid, 1,3-naphthalene disulfonic acid, 1,3,6-naphthalene trisulfonic acid, and 6-ethyl-1-naphthalene sulfonic acid. It is done. Examples of the derivatives of anthraquinone sulfonic acid include anthraquinone-1-sulfonic acid, anthraquinone-2-sulfonic acid, anthraquinone-2,6-disulfonic acid, and 2-methylanthraquinone-6-sulfonic acid. Of these, polystyrene sulfonic acid is preferable. A suspension in which poly (3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid is stably dispersed in an aqueous solvent is obtained. Moreover, it is known that the conductive polymer composition obtained from the suspension solution has high conductivity.

(Graphite layer)
The graphite layer 4 can be formed using a graphite paste in which graphite (graphite) powder is dispersed in a predetermined solvent (diluent) together with a binder. The particle size and amount of graphite can be adjusted as appropriate so that desired conductivity can be imparted.

(Silver layer)
The silver layer 5 can be formed using a silver paste in which silver fine particles are dispersed in a predetermined solvent (diluent) together with a binder. The particle size and amount of the silver fine particles can be appropriately adjusted so that desired conductivity can be imparted.
Commercially available products can be used as the graphite paste and silver paste. Further, instead of the graphite layer, a conductive layer to which a carbon material such as carbon black is added may be formed.

[Non-halogen phosphazene compounds]
The non-halogen phosphazene compound is not particularly limited as long as it has an effect as a flame retardant, but a phosphazene compound substituted with an aryloxy group and a crosslinked product thereof are preferable. For example, a cyclic phenoxyphosphazene compound represented by the general formula (A) or a linear or branched phenoxyphosphazene compound represented by the general formula (B) is exemplified. Of these, cyclic phenoxyphosphazene compounds are particularly preferred from the viewpoint of flame retardancy.

(In the formula, m represents an integer of 3 to 25, and Ph represents a phenyl group.)

Wherein X ¹ represents a group —N═P (OPh) ₃ or a group —N═P (O) OPh, and Y ¹ represents a group —N═P (OPh) ₄ or a group —N═P (O). (OPh) ₂ is shown, n is an integer of 3 to 1000, and Ph is a phenyl group.)
Further, the compound represented by the general formula (A) or (B) is selected from the group consisting of an o-phenylene group, an m-phenylene group, a p-phenylene group, and a bisphenylene group represented by the general formula (C). A crosslinked phenoxyphosphazene compound crosslinked by at least one crosslinking group can also be used as a suitable compound.

(In the formula, A represents —C (CH ₃ ) ₂ —, —SO ₂ —, —S— or —O—, and z represents 0 or 1).

  In the crosslinked phenoxyphosphazene compound, the cyclic phenoxyphosphazene compound (A) and / or the chain phenoxyphosphazene compound (B) is used as the phenoxyphosphazene compound, and the phenylene-based crosslinking group is a phenyl group of the phenoxyphosphazene compound. The content of phenyl groups in the bridged phenoxyphosphazene compound is 50 to 99.9% based on the total number of phenyl groups in the phenoxyphosphazene compound. A phenylene-based crosslinked phenoxyphosphazene compound having at least one phenolic hydroxyl group within the range is more preferable.

  The addition amount of these non-halogen phosphazene compounds is preferably 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the solid content of the solid electrolyte from the viewpoint of the flame retardant effect, and more preferably 100 parts by mass of solid content of the solid electrolyte. On the other hand, 2 to 30 parts by mass is more preferable. 5 parts by mass or more and 20 parts by mass or less are particularly preferable with respect to 100 parts by mass of the solid content of the solid electrolyte. When the addition amount of the non-halogen phosphazene compound is small, the flame retardancy is lowered. Moreover, when there is much addition amount, there exists an influence on the electrical conductivity fall of a solid electrolyte.

[solvent]
The solvent for dissolving the non-halogen phosphazene compound is not particularly limited as long as it can dissolve the non-halogen phosphazene compound, but a solvent having an SP value of 8 to 15 can be selected. By using a solvent having an SP value of 8 or more and 15 or less, the non-halogen phosphazene compound is dissolved, so that it can be uniformly distributed in the solution. Examples of the solvent having an SP value of 8 to 15 include cyclohexane, butyl acetate, isobutyl acetate, methyl isoacetate, ethylene glycol diethyl ether, diethylene glycol monobutyl ether acetate, methyl isopropyl ketone, ethylene glycol dimethyl ether, and dipropylene glycol methyl ether. , Tripropylene glycol monomethyl ether, methyl propyl ketone, methyl ethyl ketone, xylene, propyl acetate, diethyl ketone, dimethyl ether, diethyl carbonate, isopropyl alcohol, propyl acetate, toluene, ethyl acetate, ethylene glycol methyl ether acetate, benzene, styrene, methyl acetate, Diethylene glycol monobutyl ether, acetone, cyclohexanone, dimethyl carbonate, ethanol Lenglycol diacetate, methyl isobutyl carbitol, dipropylene glycol, propylene glycol methyl ether, acetic acid, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, butyl alcohol, N, N-diethylformamide, hexanol, N, N-dimethylacetamide, ethylene Glycol monobenzyl ether, ethylene glycol monophenyl ether, propyl alcohol, cyclohexanol, acetonitrile, N, N-dimethylformamide, diethylene glycol, γ-butyrolactone, methyl glycol, propylene glycol, ethanol, propylene carbonate, N-ethyleneformamide, phenol, Dimethyl sulfoxide, methanol, ethylene glycol, ethanol Tylene carbonate or the like can be used. The SP value is preferably 8 to 12, more preferably 8 to 10, and particularly preferably a solvent having a carbonyl group. Examples of the solvent having a carbonyl group include methyl ethyl ketone, acetone, cyclohexanone, N, N-dimethylformamide and the like, and these are particularly preferable because they are compatible with water.

The solvent may be a mixed solvent with other solvent, and the other solvent is not particularly limited as long as the SP value is within the above range in the mixed solvent at that time. For example, water has an SP value of 23.4, which is outside the above SP value range, and does not dissolve non-halogen phosphazene compounds, but is compatible with water and combined with a solvent within the above SP value range. A solution in which a non-halogen phosphazene compound is dissolved can be prepared.
Alternatively, after the non-halogen phosphazene compound is once dissolved in the above solvent, the obtained solution may be added to another solvent. By adding in a solution state in this way, it becomes possible to uniformly distribute the non-halogen phosphazene compound, which is a flame retardant, in the solution. Depending on the SP value and mixing ratio of other solvents, non-halogen phosphazene compounds may be precipitated. In that case, it is preferable to uniformly disperse the non-halogen phosphazene compound in the solvent by using the following additives and other methods.
As described above, the non-halogen phosphazene compound added in a solution state is precipitated by evaporation of the solvent or when the solution of the non-halogen phosphazene compound is added to another liquid (hereinafter referred to as “dissolution”). The “precipitate” has a particle size much smaller than that of the powder of the original non-halogen phosphazene compound, and the uneven distribution of the flame retardant effect is less than when the powder is dispersed as it is. As a result, a good flame retardant effect can be imparted.

In order to uniformly disperse the dissolved precipitate of the non-halogen phosphazene compound in the liquid, it is preferable to add various additives.
The first is a dispersant. There are a low molecular type and a high molecular type dispersant. Examples of the low molecular weight dispersant include alkyl sulfonic acid type, quaternary ammonium type, higher alcohol ester type and the like. Examples of the polymer dispersant include hydroxypropyl methylcellulose, polyethylene oxide, and polyvinylpyrrolidone.
The second is a silane coupling agent. Examples of silane coupling agents include vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and β- (3,4-epoxycyclohexene. Xyl) ethyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl -Γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane and the like.
Further, as a method for uniformly dispersing the dissolved precipitate of the non-halogen phosphazene compound in the liquid, a mechanical dispersion method can be considered in addition to the addition of the additive. For example, there are methods using an ultrasonic wave, a bead mill, a ball mill, a homogenizer and the like.
Any of the above additive addition and mechanical dispersion methods is not particularly limited because it is effective in uniformly dispersing the dissolved precipitate of the non-halogen phosphazene compound in the liquid.

[Method for adding non-halogen phosphazene compound]
The addition method of the non-halogen phosphazene compound in the solid electrolyte layer 3 (entire region or between layers of the solid electrolyte) and in a close part (immediately above the oxide film, outside the solid electrolyte) is as follows.

First, the addition method of the non-halogen phosphazene compound in the solid electrolyte layer (entire area) differs depending on the formation method of the solid electrolyte layer.
For example, when the solid electrolyte is a conductive polymer, the addition method differs depending on the method of forming the conductive polymer layer. When a conductive polymer layer is formed on a dielectric layer by applying a conductive polymer solution (coating, dipping, etc.), a solvent selected from solvents having an SP value of 8 to 15 (hereinafter referred to as “selected solvent”). Or a mixed solution prepared by mixing a solution in which a non-halogen phosphazene compound is dissolved in a mixed solvent of the selected solvent and other solvent and a solution in which a conductive polymer is dissolved or a dispersed dispersion. Form. The conductive polymer and the non-halogen phosphazene compound may be dissolved or uniformly dispersed in the mixed solution. There are two methods for forming a conductive polymer layer using chemical oxidative polymerization. First, a conductive polymer layer is formed in advance on a dielectric layer by chemical oxidative polymerization (hereinafter referred to as chemical chemistry). In this chemical polymerization layer, a solution in which a non-halogen phosphazene compound is dissolved in the selected solvent or a mixed solvent with another solvent is soaked, and only the solvent is volatilized to enter the chemical polymerization layer. Non-halogen phosphazene compounds are included. In the second method, either a monomer or a dopant used for chemical oxidative polymerization is dissolved in the selected solvent or a mixed solvent of the selected solvent and another solvent, and a non-halogen phosphazene compound is further dissolved. Using these solutions, a conductive polymer layer is formed by chemical oxidative polymerization. At this time, the non-halogen phosphazene compound may be dissolved in both the monomer solution and the dopant solution. When the conductive polymer layer is formed using electrolytic polymerization, the monomer, dopant and non-halogen phosphazene compound used for electrolytic polymerization are dissolved in the selected solvent or a mixed solvent of the selected solvent and other solvents. And formed by electrolytic polymerization in the solution.

  When the solid electrolyte is manganese dioxide, manganese nitrate and a non-halogen phosphazene compound are dissolved in the selected solvent or a mixed solvent of the selected solvent and other solvents. Alternatively, a solution in which a non-halogen phosphazene compound is dissolved in a manganese nitrate solution may be added. Thereafter, it is thermally decomposed to form a manganese dioxide layer. From the viewpoint of preventing decomposition of the non-halogen phosphazene compound by heat, the thermal decomposition temperature is preferably equal to or higher than the decomposition temperature of manganese nitrate and lower than the decomposition temperature of the non-halogen phosphazene compound. Usually, thermal decomposition can be performed at a temperature of about 200 ° C to 250 ° C.

  FIG. 2 shows a cross-sectional view of the capacitor element in the case where a non-halogen phosphazene compound is added to the entire area of the solid electrolyte layer. 11 schematically shows the presence of a non-halogen phosphazene compound. In practice, dissolved precipitates of non-halogen phosphazene compounds are distributed in a microcrystalline dispersion state or a film state. The same applies to the following figures. In the example shown in FIG. 2, the second conductive polymer layer 3B formed by applying or dipping a conductive polymer solution in the first conductive polymer layer 3A formed by chemical oxidative polymerization or electrolytic polymerization. Both of them are added with a non-halogen phosphazene compound 11 at the time of their formation so that they are evenly distributed over the entire area. However, the non-halogen phosphazene compound 11 may be added only to the entire region of the first conductive polymer layer 3A or only to the entire region of the second conductive polymer layer 3B. Therefore, the non-halogen phosphazene compound may be contained uniformly in a layered manner in at least one layer of the solid electrolyte. 2 to 5 show a mode in which a void is formed between the first conductive polymer layer 3A and the second conductive polymer layer 3B in the hole portion of the anode conductor 1. However, this allows the formation of voids and does not require the formation of voids.

  In addition, when the solid electrolyte layer 3 is gradually thickened in several steps, a solution in which a non-halogen phosphazene compound is dissolved is applied to the previously formed solid electrolyte layer. The anode body having the solid electrolyte layer previously formed in the solution can be immersed (dipped), dried by heating and removed to remove the solvent. Thereafter, the remaining solid electrolyte layer is formed. FIG. 3 shows an example in which the non-halogen phosphazene compound 11 is added between the layers of the second conductive polymer layer 3B. After the formation of the first conductive polymer layer 3A, a solution in which a non-halogen phosphazene compound is dissolved is applied or immersed on the first conductive polymer layer 3A, and the first conductive polymer layer 3A. A part of the surface layer or the entire conductive polymer layer 3A may be impregnated with a non-halogen phosphazene compound.

  Next, a method for adding a non-halogen phosphazene compound to a portion adjacent to the solid electrolyte layer (immediately above the oxide film, outside the solid electrolyte) is the non-halogen phosphazene compound mixed with the selected solvent or other solvent. The compound is dissolved in advance, and the solution is applied, for example, directly on the oxide film or outside the solid electrolyte layer, or the anode body after the oxide film is formed on the solution or the anode body after the solid electrolyte layer is formed. And then drying by heating to remove the solvent, whereby a layer of a non-halogen phosphazene compound dissolved precipitate can be formed. 4 and 5, the cross section of the capacitor element when the non-halogen phosphazene compound 11 is added directly above the oxide film (dielectric film 2) or outside the solid electrolyte layer 3 (under the graphite layer 4). The figure is shown.

Furthermore, a combination of FIG. 2 and FIG. 4 and / or FIG. 5 or a combination of FIG. 3 and FIG. 4 and / or FIG.
Eventually, the solvent in which the non-halogen phosphazene compound was dissolved is removed, and the non-halogen phosphazene compound precipitates as a solid (dissolved precipitate). As described above, the original powder of the non-halogen phosphazene compound Compared to the above, it is in a finely dispersed state with a very small particle size or a film-like product of a non-halogen phosphazene compound. Thus, in the present invention, the water-resistant non-halogen phosphazene compound can be added as a uniform distribution layer of the flame retardant in the solid electrolyte layer and in the vicinity thereof.

  As a method for forming the graphite layer 4, the above-described graphite paste is applied on the solid electrolyte layer 3, or the anode pellet formed with the solid electrolyte layer 3 is immersed in the graphite paste, and the solvent is removed from the graphite paste. The method of doing is mentioned. Removal of the solvent from the graphite paste can be performed by drying. The drying temperature is not particularly limited as long as the solvent can be removed, but the upper limit temperature is preferably less than 300 ° C. from the viewpoint of preventing deterioration of the lower solid electrolyte layer due to heat. The drying time must be appropriately optimized depending on the drying temperature, but is not particularly limited as long as the conductivity is not impaired.

  As a method for forming the silver layer 5, there is a method in which the above silver paste is applied on the graphite layer 4 or an anode pellet in which the graphite layer 4 is formed is immersed in the silver paste, and the solvent is removed from the silver paste. Can be mentioned. Removal of the solvent from the silver paste can be performed by drying. The drying temperature is not particularly limited as long as the solvent can be removed, but the upper limit temperature is preferably less than 300 ° C. from the viewpoint of preventing deterioration of the lower solid electrolyte layer due to heat. The drying time must be appropriately optimized depending on the drying temperature, but is not particularly limited as long as the conductivity is not impaired.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited only to these Examples.

Examples 1-44, Comparative Examples 1-4
A sintered body of fine tantalum powder (valve metal porous body) was selected as the anode conductor 1.
As shown in FIG. 1, a solid electrolytic capacitor according to an embodiment of the present invention includes an anode conductor 1 having a metal lead 8 as an anode side electrode, and a dielectric layer obtained by anodizing the surface of the anode conductor 1. 2, a solid electrolyte layer 3, a cathode layer composed of a graphite layer 4 and a silver layer 5, a conductive adhesive 6 and an external electrode 7, and an exterior resin 9. A solid electrolytic capacitor was manufactured by the following method.
The sintered body of fine tantalum powder was anodized at 16 V in an aqueous phosphoric acid solution to obtain a pellet in which the entire surface of the fine tantalum powder was covered with the dielectric layer 2. Next, the amount of the flame retardant shown in Table 1 was changed, the location of addition, and the type of solid electrolyte, and the solid electrolyte layer 3 was formed by the method shown in Table 1.

  Here, as the conductive polymer solution used in the dip method, a conductive polymer solution containing poly (3,4-ethylenedioxythiophene), polystyrenesulfonic acid as a dopant, and water as a solvent was prepared. As for the conductive polymer, referring to Japanese Patent No. 2636968, 3,4-ethylenedioxythiophene (hereinafter abbreviated as EDT) which is a monomer, and polystyrene sulfonic acid (hereinafter referred to as PSS) which functions as a dopant and a dispersant. Are mixed in water so that the mass ratio becomes EDT / PSS = 1/3, and a polymerization reaction is caused by chemical oxidative polymerization. After the polymerization reaction, impurities such as unreacted monomers are removed, and the remainder is removed. Obtained as a conductive polymer solution. In the obtained conductive polymer solution, the combined content of the conductive polymer and the dopant was 1.0% by mass.

  In the chemical oxidative polymerization, pellets were immersed in a solution mixed with water so that the mass ratio of EDT and PSS was EDT / PSS = 1/3, and a polymerization reaction was performed by chemical oxidative polymerization.

  In the electropolymerization, the pellet is immersed in a solution mixed with water so that the mass ratio of EDT and PSS is EDT / PSS = 1/3, and the polymerization reaction is performed by electropolymerization using a carbon electrode as a counter electrode. I let you.

In the case of manganese dioxide, the pellet was immersed in an aqueous manganese nitrate solution having a concentration of 20% by mass, and then thermally decomposed at a temperature of 230 ° C., and this was repeated a plurality of times.
As the non-halogen phosphazene compound of the example, a crosslinked phenoxyphosphazene oligomer (manufactured by Otsuka Chemical, trade name “SPB-100”, referred to as flame retardant 1) is used, and cyclohexanone (SP value = 9.9) is used as a solvent. A 20 mass% flame retardant solution was prepared. In Comparative Examples 3 and 4, triphenyl phosphate (referred to as Flame Retardant 2) was added as a flame retardant as a powder.

Addition points are as follows.
A: Interface between dielectric layer and solid electrolyte B: In solid electrolyte C: Solid electrolyte layer D: Interface between solid electrolyte and graphite layer

About the addition site | part A, the flame retardant solution was apply | coated on the dielectric material layer, the solvent was dried and removed at 160 degreeC, and this was repeated until it became a regular addition amount.
About the addition location B, according to the manufacturing method of each solid electrolyte, it added to the solution of each solid electrolyte or its precursor so that a flame retardant might become a regular addition amount. In the examples, the flame retardant solution was used, and in the comparative examples, the flame retardant 2 was added as a powder to the solution.
About the addition location C, each solid electrolyte was formed in several steps, the flame retardant solution was apply | coated in the meantime, and it dried and formed at 160 degreeC. Those having a large addition amount were added in a plurality of layers.
For the addition site D, after forming each solid electrolyte layer, the flame retardant solution is applied on the solid electrolyte layer, the solvent is removed by drying at 160 ° C., and this is repeated until the specified addition amount is reached. Added.

  Then, after immersing and pulling up pellets in the graphite paste, drying was performed at 120 ° C. for 1 hour to form a graphite layer 4. After the formation of the graphite layer 4, the pellet was dipped in the silver paste and pulled up, and then dried at 120 ° C. for 1 hour to form the silver layer 5. Then, the conductive adhesive 6, the external electrode 7, and the exterior resin 9 were formed in order, and the solid electrolytic capacitor 10 was manufactured.

  The thus produced solid electrolytic capacitor was measured for electrostatic capacity at 120 Hz and ESR at 100 kHz. Next, an ignition check test was performed on the solid electrolytic capacitor. After mounting each capacitor on a printed circuit board, apply an overvoltage of 32V, which is twice the anodic oxidation voltage, short-circuit the capacitor element, and whether or not the capacitor element smokes / fires in a state where an overcurrent of 3A is applied I confirmed. In addition, 50 each level was used for the test, and the number of capacitor elements that smoked (number of smokes) and the number of capacitor elements that ignited (number of fires) were counted. For flame retardancy, the number of smoke was 5 or less, the number of fires was 0, and the others were x.

  The application of an overvoltage of 32 V and an overcurrent of 3 A is a severe condition (destructive test) that cannot be realized in a normal use state for a solid electrolytic capacitor. Table 1 shows the results.

  In Examples, the flame retardant properties were all high when the addition amount of the non-halogen phosphazene compound was 1 to 50 parts by mass with respect to 100 parts by mass of the solid electrolyte solid content. Moreover, if the addition amount was up to 20 parts by mass, it was confirmed that the ESR values were the same as those of Comparative Examples 1 and 2 in which no flame retardant was added, and there was almost no influence on ESR. If the addition amount was up to 50 parts by mass, it was confirmed that ESR was within an allowable range. In Comparative Examples 3 and 4 using triphenyl phosphate (flame retardant 2) having hydrolyzability, the flame retardant was hydrolyzed during the production of the solid electrolyte, and the flame retardancy could not be sufficiently imparted.

1: anode conductor 2: dielectric layer 3: solid electrolyte layer 3A: first conductive polymer layer 3B: second conductive polymer layer 4: graphite layer 5: silver layer 6: conductive adhesive 7: electrode 8: Metal lead (valve action metal)
9: Exterior resin 10: Solid electrolytic capacitor 11: Non-halogen phosphazene compound

Claims (16)

A solid electrolytic capacitor comprising an anode conductor, a dielectric layer formed on the anode conductor, a solid electrolyte formed on the dielectric layer, and a cathode layer formed on the solid electrolyte,
A solid electrolytic capacitor having a layer containing a dissolved precipitate of a non-halogen phosphazene compound in the solid electrolyte or at an interface with another layer in contact with the solid electrolyte.   The solid electrolytic capacitor according to claim 1, wherein the non-halogen phosphazene compound is distributed throughout at least one layer of the solid electrolyte.   The solid electrolytic capacitor according to claim 1, wherein the non-halogen phosphazene compound is distributed between layers of the solid electrolyte.   The solid electrolytic capacitor according to claim 1, wherein the non-halogen phosphazene compound is distributed at an interface between the solid electrolyte and the dielectric layer.   The solid electrolytic capacitor according to claim 1, wherein the non-halogen phosphazene compound is distributed at an interface between the solid electrolyte and the cathode layer.   The solid electrolytic capacitor according to claim 1, wherein the non-halogen phosphazene compound is contained in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the solid content of the solid electrolyte. The non-halogen phosphazene compound is a cyclic phenoxyphosphazene compound represented by the following general formula (A), a linear or branched phenoxyphosphazene compound represented by the following general formula (B), or a general formula (A) or ( The compound of B) is crosslinked by at least one crosslinking group selected from the group consisting of an o-phenylene group, an m-phenylene group, a p-phenylene group, and a bisphenylene group represented by the general formula (C). The solid electrolytic capacitor according to claim 1, wherein the solid electrolytic capacitor is selected from crosslinked phenoxyphosphazene compounds.

(In the formula, m represents an integer of 3 to 25, and Ph represents a phenyl group.)

Wherein X ¹ represents a group —N═P (OPh) ₃ or a group —N═P (O) OPh, and Y ¹ represents a group —N═P (OPh) ₄ or a group —N═P (O). (OPh) ₂ is shown, n is an integer of 3 to 1000, and Ph is a phenyl group.)

(In the formula, A represents —C (CH ₃ ) ₂ —, —SO ₂ —, —S— or —O—, and z represents 0 or 1).   A method for producing a solid electrolytic capacitor according to any one of claims 1 to 7, wherein the non-halogen phosphazene compound is dissolved in a solvent and added.   The method for producing a solid electrolytic capacitor according to claim 7, wherein the solvent is a solvent having a solubility parameter (SP value) of 8 to 15.   The method for producing a solid electrolytic capacitor according to claim 8, wherein the solid electrolyte contains a conductive polymer.   The method for producing a solid electrolytic capacitor according to claim 10, wherein the solid electrolyte containing the conductive polymer is formed by chemical oxidative polymerization or electrolytic polymerization of a solution containing the non-halogen phosphazene compound and a conductive monomer.   The solid electrolyte containing the conductive polymer is formed using a mixed solution prepared by mixing a solution in which the non-halogen phosphazene compound is dissolved and a solution or dispersion in which the conductive polymer is dissolved. The manufacturing method of the solid electrolytic capacitor of Claim 10 or 11 to be performed.   The method for producing a solid electrolytic capacitor according to claim 8 or 9, wherein the solid electrolyte contains manganese dioxide.   The solid electrolyte containing manganese dioxide is a mixture of a solution in which the non-halogen phosphazene compound is dissolved and a solution in which manganese nitrate is dissolved or a dispersed dispersion, or a solution in which the non-halogen phosphazene compound and manganese nitrate are dissolved. The method for producing a solid electrolytic capacitor according to claim 13, wherein the solution is formed by thermal decomposition of the solution.   15. The method according to claim 8, further comprising: forming a dielectric layer on the anode conductor, and then applying a solution in which the non-halogen phosphazene compound is dissolved to the dielectric layer to remove the solvent. The manufacturing method of the solid electrolytic capacitor of description.   16. The method according to claim 8, further comprising: forming a dielectric layer and a solid electrolyte on the anode conductor, and then applying a solution in which the non-halogen phosphazene compound is dissolved to the solid electrolyte to remove the solvent. 2. A method for producing a solid electrolytic capacitor according to item 1.

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