JP2008166592A - Method for manufacturing anode body for solid electrolytic capacitor and anode for solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an anode for a solid electrolytic capacitor which has a sufficient opening gap and meanwhile can obtain a metal sintered compact having a high mechanical strength, and the anode for the solid electrolytic capacitor. <P>SOLUTION: The method for manufacturing the anode for the solid electrolytic capacitor has: a step 1 of mixing a sintering property metal particle, a heating annihilation property resin particle containing a polyoxyalkylene resin and a dispersive solvent, and preparing and drying a mixture; a step 2 of molding the mixture, thereby molding a molding; and a step 3 of sintering the molding. In the method for manufacturing the anode for the solid electrolytic capacitor, the mixture contains the heating annihilation property resin particle having a solids content ratio of 0.01 to 20 wt.% with respect to the sintering property metal particle, and the heating annihilation property resin particle has a mean particle size of 0.1 to 5 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method for producing a solid electrolytic capacitor anode body and a solid electrolytic capacitor anode body capable of obtaining a metal sintered body having high mechanical strength while having sufficient voids.

The use of solid electrolytic capacitors is rapidly expanding as a capacitor element used in mobile phones, personal computers, digital cameras and the like.
FIG. 3 is a cross-sectional view schematically illustrating the structure of the solid electrolytic capacitor. The solid electrolytic capacitor 11 has a structure in which an anode layer 12 made of a metal such as aluminum is opposed to a cathode layer 15 with an oxide film 13 and an electrolyte layer 14 interposed therebetween. Here, since the exchange of electrons is performed through the interface between the oxide film 13 and the electrolyte layer 14 in contact with the anode layer 12, in order to obtain a capacitor having a larger capacity, the anode layer 11, the oxide film 13 and the electrolyte are used. It is effective to increase the surface area of the interface with the layer 14.

As a method of forming an anode body having a large surface area, conventionally, a method such as etching the surface of the anode body has been performed. However, in order to increase the capacity, a sintered metal body having pores is used as the anode body. It has been proposed to be used as
As a method for producing a sintered metal body having pores, for example, to a fine powder of valve action metal such as aluminum, a binder mixed with camphor or acrylic resin or the like and mixed with an organic solvent, and then mixed, An organic processing valve action metal fine powder that has been removed by volatilization of an organic solvent has been used, and after press-molding it, a method of sintering by heating at high temperature in vacuum has been performed. However, in this method, the pore diameter of the pores of the obtained metal sintered body becomes too small, and it becomes difficult to form an oxide film or an electrolyte layer inside the pores, and a sufficient surface area expansion effect cannot be obtained. There was a problem that the capacity expansion effect of the solid electrolytic capacitor could not be obtained.

On the other hand, Patent Document 1 discloses a method of using a granular binder having a particle diameter of 50 μm or less as a valve action metal binder when manufacturing a sintered metal body. According to this method, since the traces of the binder remain as pores when the binder is removed during sintering, a sintered metal body in which pores having relatively large pore diameters are uniformly formed is obtained. The use of the bonded body as the anode layer is said to improve the equivalent series resistance and tan δ characteristics of the solid electrolytic capacitor.

However, in the method described in Patent Document 1, when a large amount of a granular binder is added in order to obtain a sintered metal body having a sufficiently high porosity, it is necessary to perform degreasing and firing for a long time at an unnecessarily high temperature. The manufacturing process requires a long time, and the metal sintered body obtained by increasing the combustion heat of the granular binder is greatly strained, which may cause cracks.

Further, in Patent Document 2, 3 to 10% by weight of a solid acrylic resin that is in the form of particles or fibers and has an average particle diameter of 1 to 100 μm is mixed with the valve action metal powder in the molding step of the molded body. A method for manufacturing a solid electrolytic capacitor is described in which a molded body is molded using powder and then sintered. When such a method is used, the obtained metal sintered body has a high porosity, so an oxide film or an electrolyte layer can be formed even inside the pores, and the resistance value is small and good. A solid electrolytic capacitor having excellent tan δ characteristics is obtained.

However, when the method of Patent Document 2 was actually used, the adhesion between valve metals was poor, and the mechanical strength of the resulting metal sintered body was low, so that the sintered body was distorted and cracked. . Moreover, the size of the pores formed in the sintered metal body was also nonuniform and varied. As a result, the produced fixed electrolytic capacitor was inferior in tan δ characteristics. Further, in the method of Patent Document 2, since a resin having low heat decomposability is used as the resin component of the binder, it cannot be sintered at a low temperature in a short time. There are also problems such as distortion and cracks, and productivity.
Therefore, there has been a demand for a method for producing an anode body for a solid electrolytic capacitor, which can obtain a metal sintered body having high mechanical strength while having sufficient voids.
JP-A-10-275746 Japanese Patent No. 2912464

In view of the above situation, the present invention can provide a sintered metal body having a high mechanical strength while having sufficient voids, and can be used for a large-capacity solid electrolytic capacitor. It is an object of the present invention to provide a manufacturing method and an anode body for a solid electrolytic capacitor.

The present invention comprises a step 1 of mixing a sinterable metal particle, a heat extinguishing resin particle containing a polyoxyalkylene resin, and a dispersion solvent to prepare and dry the mixture, and molding the mixture to form a molded body. A solid electrolytic capacitor anode body having a step 2 and a step 3 for sintering the molded body, wherein the mixture has a solid content ratio of 0.01 to the sinterable metal particles. It is a manufacturing method of the anode body for solid electrolytic capacitors containing -20weight% of heat extinction resin particles, and the said heat extinction resin particles are 0.1-5 micrometers in average particle diameter.
The present invention is described in detail below.

As a result of intensive studies, the inventors have mixed the heat-extinguishing resin particles having a predetermined average particle diameter and content and a dispersion solvent with respect to the sinterable metal particles, and performing molding and sintering, Solid electrolysis that can be used for large-capacity solid electrolytic capacitors because it has high mechanical strength while having sufficient voids, so that it can obtain a sintered metal that does not generate distortion or cracks. The inventors have found that an anode body for a capacitor can be obtained, and have completed the present invention.

In the method for producing an anode body for a solid electrolytic capacitor of the present invention, first, Step 1 of mixing sinterable metal particles, heat-extinguishing resin particles containing a polyoxyalkylene resin, and a dispersion solvent to prepare and dry the mixture is performed. Do. In addition, after mixing the sinterable metal particles, the heat extinguishing resin particles and the dispersion solvent, the step of drying to produce particles composed of the sinterable metal particles and the heat extinguishing resin particles (granulation step) is also a step. 1 included.

FIG. 1 is a schematic diagram showing a mixed state of sinterable metal particles and heat-extinguishing resin particles after performing Step 1 of the present invention and granulating. As shown in FIG. 1, in the present invention, by adding and mixing a heat extinguishing resin particle 2 having a predetermined average particle diameter described later in a predetermined addition amount, the sinterable metal particles 1 are Contact is made by point contact. As a result, in the subsequent sintering step, since the bonding between the sinterable metal particles 1 becomes very strong when sintering is performed, the sintered metal obtained after the sintering has a mechanical strength. It will be excellent. Moreover, since the sinterable metal particles 1 have an appropriate interval, the obtained metal sintered body has large pores and uniform voids.
On the other hand, FIG. 2 is a schematic diagram showing a mixed state of the sinterable metal particles and the binder when granulation is performed by a conventional method in which a liquid binder is added to the sinterable metal particles as a raw material. As shown in FIG. 2, when a liquid binder is used, since the binder 3 exists in a film shape around the sinterable metal particles 1, the sinterable metal particles 1 are less likely to come into contact with each other, and the sinterability The space between the metal particles 1 is also reduced. Therefore, the obtained metal sintered body has a low porosity and inferior mechanical strength.

In the present invention, in step 1 above, the sinterable metal particles, the heat extinguishing resin particles containing the polyoxyalkylene resin, and the dispersion solvent are mixed to prepare a mixture.
In the above step 1, it is preferable to prepare a mixture by mixing sinterable metal particles and a slurry in which heat extinguishing resin particles are dispersed in a dispersion solvent.
Since the slurry is liquid, it is easy to handle, and in the mixing step, the sinterable metal particles and the heat extinguishing resin particles can be mixed uniformly, and granulation can be suitably performed. In addition, when mixing is performed using the slurry, the resin is not formed into a film as shown in FIG. 2, and sintering is performed while the sinterable metal particles are in point contact as shown in FIG. 1. The conductive metal particles are in a state of forming appropriate voids. Therefore, by using the slurry, the advantages of both the case of using a liquid binder and the case of using a solid powder binder can be enjoyed.

The said mixture contains 0.01-20 weight% of heat extinction resin particles by solid content ratio with respect to sinterable metal particles. If it is less than 0.01% by weight, a metal sintered body having sufficient voids cannot be obtained, and if it exceeds 20% by weight, the strength of the obtained metal sintered body is inferior. A preferred lower limit is 0.1% by weight and a preferred upper limit is 10% by weight.

In the above mixture, the preferable lower limit of the resin solid content is 1% by weight, and the preferable upper limit is 70% by weight. When the amount is less than 1% by weight, the sinterable metal particles, the heat extinguishing resin particles and the dispersion solvent are mixed, and the dispersion solvent is volatilized to obtain particles composed of the sinterable metal particles and the heat extinction resin particles. When granulating, handling properties and productivity may be reduced, and when it exceeds 70% by weight, the viscosity of the mixture becomes high, and the dispersibility and handling properties of the sinterable metal particles may be reduced. .

Although it does not specifically limit as said sinterable metal particle, For example, a tantalum, aluminum, niobium, titanium etc. and these alloys etc. are mentioned.
Although it does not specifically limit as an average particle diameter of the said sinterable metal particle, A preferable minimum is 1 micrometer and a preferable upper limit is 300 micrometers.

The heat extinguishing resin particles contain a polyoxyalkylene resin.
The above polyoxyalkylene resin is decomposed into low molecular weight hydrocarbons, ethers, etc. by heating to a predetermined temperature in a non-oxygen or low oxygen concentration atmosphere, and then disappears due to a phase change such as combustion reaction or evaporation. Exhibits extremely excellent heat extinction properties.
This is because the polyoxyalkylene resin has many oxygen atoms in the molecule, and therefore the polyoxyalkylene resin itself works as an oxygen supply source even when heated in a non-oxygen or low oxygen concentration atmosphere. It is done.

Although it does not specifically limit as said polyoxyalkylene resin, It is preferable to contain polyoxypropylene, polyoxyethylene, or polyoxytetramethylene. When these polyoxyalkylene resins are not contained, predetermined heat extinction properties and particle strength may not be obtained. Of these, polyoxypropylene is more preferable. In order to obtain moderate heat extinction properties and particle strength, it is preferable that 5% by weight or more of the polyoxyalkylene resin contained in the heat extinction resin particles is polyoxypropylene. Moreover, polyoxyethylene shall contain ethylene glycol.

Examples of commercially available polyoxyalkylene resins include MS polymers S-203, S-303, and S-903 (manufactured by Kaneka Corporation); Silyl SAT-200, MA-403, and MA-447. (Above, manufactured by Kaneka Corporation); Epion EP103S, EP303S, EP505S (above, manufactured by Kaneka Corporation); Exester ESS-2410, ESS-2420, ESS-3630 (above, manufactured by Asahi Glass Co., Ltd.)

Although it does not specifically limit as molecular weight of the said polyoxyalkylene resin, The minimum with a preferable number average molecular weight is 300, and a preferable upper limit is 1 million. If it is less than 300, high heat extinction may not be realized, and if it exceeds 1,000,000, high particle strength may not be realized.

In the heat extinguishing resin particles, the preferred lower limit of the content of the polyoxyalkylene resin is 5% by weight. If it is less than 5% by weight, the heat extinction property may not be sufficiently realized.

The polyoxyalkylene resin preferably further contains a crosslinking component.
By containing the crosslinking component, the compressive strength of the heat extinguishing resin particles can be improved. For this reason, when the heat extinguishing resin particles and the inorganic powder are mixed and molded, the handling property can be improved without causing destruction of the resin particles at normal temperature. Moreover, the resin particle can be made not to swell in the organic solvent by containing the crosslinking component.
The crosslinking component is not particularly limited, and examples thereof include an acrylic polyfunctional monomer such as trimethylolpropane tri (meth) acrylate, divinylbenzene, and a macromonomer having two or more functional groups described later. .

The heat extinguishing resin particles preferably further contain an acrylic monomer polymer. The acrylic monomer polymer is easily depolymerized and excellent in thermal decomposability, and the coexistence with the polyoxyalkylene resin can further improve the decomposability.

The acrylic monomer polymer is not particularly limited. For example, ethyl acrylate, propyl acrylate, n-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, butyl methacrylate, methyl methacrylate, butyl methacrylate, isobutyl methacrylate. And the like.
A polymer of an acrylic polyfunctional monomer such as trimethylolpropane tri (meth) acrylate is preferably used.

In the heat extinguishing resin particles, the preferred upper limit of the content of the acrylic monomer polymer is 99% by weight. If it exceeds 99% by weight, the content of the polyoxyalkylene resin becomes too small, and the decomposition promoting effect may not be sufficiently obtained. A more preferred lower limit is 50% by weight, and a more preferred upper limit is 97% by weight.

The above heat extinguishing resin particles have a preferred lower limit of 10% compressive strength at 23 ° C. of 1 MPa and a preferred upper limit of 1000 MPa. When the pressure is less than 1 MPa, resin particles are destroyed at room temperature, and thus handling properties may be deteriorated when molding with mixing with inorganic powder. If it exceeds 1000 MPa, the molding machine screw may be damaged when it is molded with inorganic powder. In this specification, the 10% compressive strength means a pressure required to compress the heat extinguishing hollow resin particles by 10% with respect to the particle diameter, such as a micro hardness tester (manufactured by Fischer). Can be measured.

The heat extinguishing resin particles are preferably not swollen in an organic solvent.
When it is swollen in an organic solvent, the strength of the heat extinguishing resin particles is reduced, and therefore, when used as a porous material, a desired pore forming effect may not be obtained.

The heat extinguishing resin particles of the present invention preferably further contain a decomposition accelerator.
In this specification, the decomposition accelerator means a substance that generates radicals at a predetermined temperature and accelerates a polymer decomposition reaction caused by radicals including depolymerization.
By containing the decomposition accelerator, the decomposition of the polyoxyalkylene resin is promoted, and the heat extinguishing resin particles can be extinguished in a short time at a lower temperature.

The decomposition accelerator is not particularly limited, and examples thereof include peroxides such as benzoyl peroxide and lauroyl peroxide, 2,2′-azobisisobutyronitrile, 2-carbamoylazoformamide, 1,1 ′. -Azo compounds such as azobiscyclohexane-1-carbonitrile.

It is preferable that 90% by weight or more of the heat extinguishing resin particles disappear within 2 hours by heating to a predetermined temperature of 100 to 350 ° C. in an atmosphere having an oxygen concentration of 5% or less.
The above heat extinguishing resin particles exhibit extremely excellent decomposability even in a low temperature region in a non-oxygen or low oxygen atmosphere, and 90% by weight or more disappears.
When the time required for disappearance of 90% by weight or more exceeds 2 hours, the production efficiency of the metal sintered body may be reduced when used for producing the metal sintered body. If the portion that disappears within 2 hours is less than 90% by weight, the heat generation amount may be reduced, and the effect of suppressing deformation may be insufficient.

As described above, after the above-described heat extinguishing resin particles are 90% by weight or more disappeared, the resin component residue is 0.01% by weight within one hour by further heating to a predetermined temperature of 200 to 400 ° C. It becomes as follows.
The heat extinguishing resin particles exhibit extremely excellent degreasing properties in a temperature range of 200 to 400 ° C., and almost no resin component such as carbon remains.
When the time required for the resin component residue to be 0.01% by weight or less exceeds 1 hour, the production efficiency decreases. If it is lower than 200 ° C., the resin component cannot be sufficiently removed, and the resin component residue may not be 0.01% by weight or less. When the temperature at which the residue of the resin component becomes 0.01% by weight or less exceeds 400 ° C., when degreasing is performed at 400 ° C. or less in order to improve the production efficiency, the resin component such as carbon remains, The obtained sinterable inorganic material may have problems such as deformation and cracks.
In the present specification, the resin component residue is a component derived from the heat extinguisher resin particles generated as a result of burning the heat extinguishable resin particles, and mainly means carbon or the like.

The lower limit of the average particle size of the heat extinguishing resin particles is 0.1 μm, and the upper limit is 5 μm.
If the particle diameter is less than 0.1 μm, it is impossible to obtain a sintered metal body having a sufficient particle size due to the particle size being too small. The mechanical strength of the body is reduced. A preferred lower limit is 0.1 μm and a preferred upper limit is 1 μm.

It does not specifically limit as a manufacturing method of the said heat extinction resin particle, For example, the polyoxyalkylene macromonomer, the mixed monomer of a polyoxyalkylene macromonomer and another polymerizable monomer, and a decomposition accelerator are contained. Examples of the polymerization method include a polymerization method using a conventionally known polymerization method such as a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, a soap-free polymerization method, and a miniemulsion polymerization method.
Among them, a method having a step of polymerizing a polyoxyalkylene macromonomer or a mixed monomer of a polyoxyalkylene macromonomer and another polymerizable monomer is preferable. In the present specification, the macromonomer refers to a high molecular weight linear molecule having a polymerizable functional group such as a vinyl group at the molecular end, and the polyoxyalkylene macromonomer is a polymer having a linear portion having a poly moiety. A macromonomer composed of oxyalkylene.

The functional group contained in the polyoxyalkylene macromonomer is not particularly limited. For example, polymerizable unsaturated hydrocarbon such as (meth) acrylate, isocyanate group, epoxy group, hydrolyzable silyl group, hydroxyl group, carboxyl group Etc. Among them, a polyoxyalkylene macromonomer containing a polymerizable unsaturated hydrocarbon capable of radical polymerization is preferable because it can more easily produce a heat-extinguishing resin particle, and a polyoxyalkylene containing a (meth) acryloyl group having high polymerization reactivity. An alkylene macromonomer is more preferred.
Further, the number of functional groups contained in the polyoxyalkylene macromonomer is not particularly limited, but if a macromonomer having two or more functional groups is used, heat extinguishing resin particles having high compressive strength can be obtained by crosslinking. Can do.

Although it does not specifically limit as molecular weight of the polyoxyalkylene unit contained in the said polyoxyalkylene macromonomer, The minimum with a preferable number average molecular weight is 300, and a preferable upper limit is 1 million. If it is less than 300, sufficient heat extinction may not be obtained, and if it exceeds 1,000,000, sufficient particle strength may not be obtained.

Specific examples of the polyoxyalkylene macromonomer include polyoxyethylene di (meth) acrylate (manufactured by NOF Corporation; Blemmer PDE-400, PDE-600, ADE-400), polyoxypropylene di (meth). Acrylate (manufactured by NOF Corporation: Blemmer PDP-400, PDP-700, ADP-400), polyoxytetramethylene di (meth) acrylate (manufactured by NOF Corporation; Blemmer PDT-650, ADT-250), polyoxyethylene- Polyoxytetramethylene methacrylate (manufactured by NOF Corporation; Bremer 55PET-800) and the like can be mentioned.

Although it does not specifically limit as another polymerizable monomer when making it copolymerize with the said polyoxyalkylene macromonomer, Since it can manufacture simply, a radically polymerizable monomer is suitable. It does not specifically limit as said radically polymerizable monomer, For example, (meth) acrylate, (meth) acrylonitrile, (meth) acrylic acid, styrene and its derivative (s), vinyl acetate, etc. are mentioned.

Furthermore, as another polymerizable monomer used together with the polyoxyalkylene macromonomer, a polyfunctional monomer may be added for the purpose of improving the particle strength. The type of the polyfunctional monomer is not particularly limited, and examples thereof include acrylic polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, divinylbenzene, and the like.

Although it does not specifically limit as another polymerizable monomer used with the said polyoxyalkylene macromonomer, Using a highly depolymerizable radically polymerizable monomer can manufacture a heat extinction resin particle easily. Preferred above. For example, (meth) acrylate, (meth) acrylonitrile, (meth) acrylic acid, styrene and its derivatives, vinyl acetate and the like can be mentioned.

Among the methods for copolymerizing the polyoxyalkylene macromonomer and other polymerizable monomers, the polyoxyalkylene macromonomer and a homopolymer having a glass transition temperature of 30 ° C. or less and 1 to 50% by weight of a monomer are contained. It is preferable to use a method of copolymerizing the mixed monomers.
When a monomer having a glass transition temperature of higher than 30 ° C. is used, (adhesion insufficient) may occur. Further, if the monomer having a glass transition temperature of 30 ° C. or less of the homopolymer is less than 1% by weight, the addition amount is too small to exhibit the effect of improving adhesiveness, and exceeds 50% by weight. In the step 2, the heat extinguishing resin particles may be deformed.

When producing the above heat extinguishing resin particles, the particles containing a polyoxyalkylene resin and a decomposition accelerator may be coated with an organic resin and encapsulated. The encapsulation method is not particularly limited, and examples thereof include a coacervation method, a submerged drying method, an interfacial polymerization method, and an in-situ polymerization method.

The dispersion solvent is not particularly limited as long as it can be dispersed without dissolving the heat extinguishing resin particles and has low toxicity. For example, water, alcohol, or the like can be used.

The method for mixing the sinterable metal particles, the heat extinguishing resin particles, and the dispersion solvent is not particularly limited. For example, various mixers such as a ball mill, a blender mill, a three roll, a hensil, and a granulating dryer are used. The method to use is mentioned.

Next, in the method for producing an anode body for a solid electrolytic capacitor of the present invention, step 2 of forming a formed body is performed by forming the mixture.
The molding method is not particularly limited, and examples thereof include a method of compression molding with a press or the like into a cylindrical shape or a square shape.

Next, in the method for producing an anode body for a solid electrolytic capacitor of the present invention, Step 3 of sintering the molded body is performed.
The method for sintering is not particularly limited, and examples thereof include a method of heating to 1000 to 2000 ° C. under reduced pressure.

According to the present invention, since the sinterable metal particles are mixed with the heat extinguishing resin particles in a point contact with each other at an appropriate interval, and can be sintered at a low temperature in a short time, sufficient voids are provided. It is possible to obtain a sintered metal body having a high mechanical strength and having no distortion or cracks. When the porous metal sintered body thus obtained is used as an anode body, since the pore diameter is appropriate, the oxide film and the solid electrolyte layer can penetrate into the pores. The surface area of the interface between the anode layer and the oxide film and the electrolyte layer can be increased. As a result, a solid electrolytic capacitor having a large capacity and high reliability can be manufactured.

A conventionally well-known method can be used as a method of manufacturing a solid electrolytic capacitor using the anode body manufactured by the manufacturing method of the anode body for solid electrolytic capacitors of this invention.
For example, a disc-shaped insulating plate made of a fluororesin, silicone rubber, silicone resin, or the like is disposed at the root of an anode lead wire drawn from a previously formed anode body made of a sintered metal. Next, the metal sintered body is immersed in a chemical conversion solution such as nitric acid or phosphoric acid, and anodized to form an oxide film having a thickness of about 200 Å to 6000 Å. After forming the oxide film, a solid electrolyte layer made of manganese dioxide or an organic conductive polymer is formed. After forming the solid electrolyte layer, a carbon paste is applied to form a carbon layer, and a silver paste is applied to the surface of the carbon layer to form a silver layer. A solid electrolyte layer, a carbon layer, and a silver layer are used as the cathode layer.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the anode body for solid electrolytic capacitors which can obtain a metal sintered compact with sufficient mechanical strength, having sufficient space | gap can be provided.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Preparation of slurry containing resin particles)
(Example 1)
A monomer solution was prepared by mixing and stirring 100 parts by weight of a monomer component having the composition shown in Table 1 and 0.3 parts by weight of azobisisobutyronitrile (AIBN) as a polymerization initiator.
The total amount of the monomer solution thus obtained is added to 300 parts by weight of an aqueous solution of 1% by weight of polyvinyl alcohol (PVA) and 0.02% by weight of sodium nitrite, and stirred using a stirring and dispersing device to obtain an emulsified suspension. It was.

Next, using a 20 liter polymerization vessel equipped with a stirrer, jacket, reflux condenser and thermometer, the inside of the polymerization vessel was depressurized, and after deoxidizing the vessel, the pressure was returned to atmospheric pressure with nitrogen gas. The inside of the polymerization vessel was set to a nitrogen atmosphere. The entire amount of the resulting emulsified suspension was charged all at once into the polymerization vessel, and the polymerization was started by raising the temperature of the polymerization vessel to 60 ° C. After polymerization for 8 hours, the polymerization vessel was cooled to room temperature to obtain a slurry.

(Example 2)
A slurry was obtained in the same manner as in Example 1 except that 100 parts by weight of the monomer component having the composition shown in Table 1 was used and 1% by weight of polyoxyethylene alkyl ether was used instead of PVA.

(Example 3)
100 parts by weight of the monomer mixed according to the composition shown in Table 1 was added to 100 parts by weight of a 1.5% by weight aqueous solution of polyoxyethylene alkyl ether and stirred using a stirring and dispersing device to obtain an emulsified suspension.
Next, using a 20 liter polymerization vessel equipped with a stirrer, jacket, reflux condenser and thermometer, the inside of the polymerization vessel was depressurized, and after deoxidizing the vessel, the pressure was returned to atmospheric pressure with nitrogen gas. The inside of the polymerization vessel was set to a nitrogen atmosphere. In this polymerization vessel, 200 parts by weight of water was charged and the polymerization vessel was heated to 60 ° C., and then 0.5 parts by weight of ammonium persulfate as a polymerization initiator and 5 parts by weight of the above emulsion suspension were used as seed monomers. To start polymerization. After aging for 30 minutes, the remaining emulsified suspension was added dropwise over 2 hours. After further aging for 1 hour, the polymerization vessel was cooled to room temperature to obtain a slurry.

Example 4
When 100 parts by weight of the monomer component having the same composition as in Example 1 is used, and when the emulsion suspension is charged into the polymerization vessel, it is not a batch, but 40 parts by weight of the emulsion suspension is added as a seed monomer for polymerization. Then, after aging for 30 minutes, a slurry was obtained in the same manner as in Example 1 except that the remaining emulsified suspension was added dropwise over 2 hours.

(Comparative Examples 1 and 2)
A slurry was obtained in the same manner as in Example 1 except that 100 parts by weight of the monomer component having the composition shown in Table 1 was used.

(1) Evaluation About the resin particles contained in the obtained slurry, by using a differential scanning calorimeter (DSC-6200, manufactured by Seiko Instruments Inc.), by measuring while raising the temperature at a heating rate of 5 ° C./min, The decomposition start temperature, 50 wt% reduction temperature, weight reduction rate at 350 ° C, and the amount of resin component residue at 400 ° C were measured. The results are shown in Table 1.
Table 1 also shows the average particle diameter of the resin particles contained in the slurry and the resin solid content of the slurry.

(Production of sintered body)
(Examples 5-9, Comparative Examples 3-6)
In accordance with the composition of Table 2, while stirring the fine powder of tantalum at 80 ° C., the resin particle-containing slurry is dropped, the resin particles are mixed with the tantalum powder, the solvent water is volatilized, and the tantalum powder is granulated. went. The obtained granulated tantalum powder was press-compressed into a square shape, then heated to 400 ° C. at a heating rate of 10 ° C./min in vacuum, and held for 1 hour to degrease the resin particles. Thereafter, sintering was performed at a heating rate of 40 ° C./h, a maximum temperature of 1400 ° C., and a holding time of 3 hours to obtain a sintered body of 1.10 mm × 1.80 mm × 1.45 mm square.

(2) Evaluation (2-1) Granulation property The granulated tantalum powder obtained in Examples and Comparative Examples is sieved with a sieve having an opening of 32 μm (500 mesh), and the pass rate of the sieve is 0.1% by weight or less. ○, those exceeding 0.1% by weight were evaluated as x.

(2-2) Strain evaluation The obtained sintered body was visually observed, and the occurrence of strain, cracks and chips was evaluated according to the following criteria.
○: No distortion, crack or chipping was observed.
X: Strain, cracks and chips were observed.

(2-3) Resin component residue ratio A differential scanning calorimeter (DSC-6200, manufactured by Seiko Instruments Inc.) was used to measure the amount of resin component residue in the sintered body.

According to the present invention, it is possible to provide a solid electrolytic capacitor anode body manufacturing method and a solid electrolytic capacitor anode body capable of obtaining a metal sintered body having high mechanical strength while having sufficient voids. it can.

It is sectional drawing which shows typically the mixed state of the sinterable metal particle and heat extinction resin particle in this invention. It is sectional drawing which shows typically the mixed state of the sinterable metal particle and binder in the conventional method. It is sectional drawing which illustrates the structure of a solid electrolytic capacitor typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sinterable metal particle 2 Heat extinction resin particle 3 Binder 11 Solid electrolytic capacitor 12 Anode layer 13 Anodized film 14 Electrolyte layer 15 Cathode layer

Claims (8)

Step 1 of mixing sinterable metal particles, heat extinguishing resin particles containing a polyoxyalkylene resin, and a dispersion solvent, preparing a mixture, and drying;
Step 2 of forming a molded body by forming the mixture, and
A method for producing an anode body for a solid electrolytic capacitor, comprising the step 3 of sintering the molded body,
The mixture contains 0.01 to 20 wt% heat extinguishing resin particles in a solid content ratio with respect to the sinterable metal particles,
The method for producing an anode body for a solid electrolytic capacitor, wherein the heat extinguishing resin particles have an average particle diameter of 0.1 to 5 μm. 2. The method for producing an anode body for a solid electrolytic capacitor according to claim 1, wherein the mixture has a resin solid content of 1 to 70% by weight. Heat extinguishing resin particles are heated to a predetermined temperature of 100 to 350 ° C. in an atmosphere having an oxygen concentration of 5% or less, and 90% by weight or more disappears within 2 hours, and 90% by weight or more disappears. 3. The anode for a solid electrolytic capacitor according to claim 1, wherein the resin component residue is 0.01% by weight or less within one hour by further heating to a predetermined temperature of 200 to 400 ° C. Body manufacturing method. The heat-extinguishing resin particles contain a copolymer obtained by polymerizing a mixed monomer containing a polyoxyalkylene macromonomer and a monomer having a glass transition temperature of 30 ° C. or less of 1 to 50% by weight. The method for producing an anode body for a solid electrolytic capacitor according to claim 1, 2, or 3. 5. The method for producing an anode body for a solid electrolytic capacitor according to claim 1, wherein the polyoxyalkylene resin contains polyoxypropylene, polyoxyethylene, or polyoxytetramethylene. 6. The method for producing an anode body for a solid electrolytic capacitor according to claim 1, wherein the polyoxyalkylene resin contains 5% by weight or more of polyoxypropylene. The method for producing an anode body for a solid electrolytic capacitor according to claim 1, wherein the dispersion solvent is water and / or alcohol. A solid electrolytic capacitor anode body manufactured using the method for manufacturing a solid electrolytic capacitor anode body according to claim 1, 2, 3, 4, 6, or 7.

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