JP2009289679A - Slurry composition for electrode formation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slurry composition for electrode formation which has a high mechanical strength with a sufficient gap and by which an electrode with excellent electrical characteristics is obtained and manufacturing cost is reduced, an electrode, and a method of manufacturing the electrode. <P>SOLUTION: This is the slurry composition for electrode formation which contains a noble metal particle, a heating disappearance resin particle containing polyoxyalkylene resin, and a dispersion solvent, and contains the heating disappearance resin particle 0.01-20 wt.% in solid ratio to the noble metal particle, and the average particle size of the heating disappearance resin particle is 0.05-10 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a slurry composition for forming an electrode, containing a noble metal and capable of producing a porous sensor electrode, an electrode, and a method for producing the electrode.

Conventionally, in order to control the air-fuel ratio of an internal combustion engine such as an automobile, research and development on a concentration cell type oxygen sensor for measuring the oxygen concentration in exhaust gas has been made. Research on electrode materials used in sensors is advancing.
As an electrode material for an oxygen sensor, for example, a cermet electrode in which a mixture of a platinum group metal powder and an oxygen ion conductive solid electrolyte fine powder is baked on an oxygen ion conductive solid electrolyte sintered body is known. ing. Patent Document 1 discloses an oxygen concentration cell having an electrode in which zirconium oxide produced by thermal decomposition of an aqueous solution of zirconium oxychloride impregnated and impregnated in a void of a porous conductive film made of a platinum group metal is incorporated. Has been.

Further, in Patent Document 2, in an electrode formed on an oxygen ion conductive solid electrolyte, an oxide mixed conductor is coated on the surface of a porous matrix made of a platinum group metal, and an oxide is formed between the platinum group metals. An oxygen sensor with a mixed conductor structure is disclosed.

On the other hand, an oxygen sensor using a noble metal such as platinum as described above has been proposed in which the electrode has a porous shape to increase the contact area with the gas. In such an oxygen sensor, high gas permeability is required in order to maximize sensitivity, but the porous shape causes problems such as breakage and has been difficult to cope with.
On the other hand, in order to improve the strength of the electrode, a method of increasing the content of the noble metal was also considered, but when the amount of the noble metal is increased, the resulting product becomes expensive. There has been a demand for an electrode-forming slurry composition that can suppress the cost and reduce the cost, and that can provide an electrode having sufficient voids and high mechanical strength.
Japanese Patent Publication No.57-10382 JP-A-5-249070

In view of the above situation, the present invention provides an electrode-forming slurry composition that can provide an electrode having sufficient voids, high mechanical strength, and excellent electrical characteristics, and capable of reducing manufacturing costs. An object is to provide an object, an electrode, and a method for manufacturing the electrode.

The present invention is a slurry composition for electrode formation containing precious metal particles, a heat extinguishing resin particle containing a polyoxyalkylene resin, and a dispersion solvent, wherein the heat extinguishing resin particle is added to the noble metal particle. The slurry composition for electrode formation containing 0.01 to 20% by weight in a solid content ratio and having an average particle diameter of the heat extinguishing resin particles of 0.05 to 10 μm.
The present invention is described in detail below.

As a result of intensive studies, the inventors have manufactured an electrode using a slurry composition for electrode formation containing a heat-extinguishing resin particle having a predetermined average particle diameter and content and a dispersion solvent with respect to noble metal particles. In that case, it has a high mechanical strength while having sufficient voids, so that an electrode free from distortion and cracks can be obtained, and the manufacturing cost can be reduced. The present invention has been completed.

The slurry composition for electrode formation of this invention contains 0.01-20 weight% of heat extinction resin particles by solid content ratio with respect to a noble metal particle. If the content of the heat extinguishing resin particles is less than 0.01% by weight, a metal sintered body having sufficient voids cannot be obtained, and the content of the heat extinguishing resin particles is 20% by weight. When exceeding, the intensity | strength of the metal sintered compact obtained is inferior. The minimum with preferable content of the said heat extinction resin particle is 0.1 weight%, and a preferable upper limit is 10 weight%.

In the slurry composition for forming an electrode of the present invention, a preferable lower limit of the resin solid content is 1% by weight, and a preferable upper limit is 70% by weight. When the resin solid content is less than 1% by weight, for example, in the subsequent step, when the particles composed of the noble metal particles and the heat extinguishing resin particles are granulated by volatilizing the dispersion solvent, the handling property and When the resin solid content exceeds 70% by weight, the viscosity of the electrode-forming slurry composition increases, and the dispersibility and handling properties of the noble metal particles may decrease.

Although it does not specifically limit as said noble metal particle, For example, platinum, gold | metal | money, silver, copper, palladium, rhodium, zinc, cobalt, indium, nickel, chromium, antimony, bismuth, germanium, cadmium etc. are mentioned. Moreover, these alloys can also be used.

The average particle diameter of the noble metal particles is not particularly limited, but a preferable lower limit is 0.05 μm and a preferable upper limit is 100 μm. When the average particle diameter of the noble metal particles is less than 0.05 μm, if the precious metal particles are left at room temperature, the sintering proceeds and becomes unstable. On the other hand, when the average particle diameter of the noble metal particles exceeds 100 μm, the difference in surface energy with respect to the bulk noble metal becomes small and the activity becomes small.

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, S-903 (manufactured by Kaneka), Silyl SAT-200, MA-403, 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.) and the like.

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. When the number average molecular weight is less than 300, high heat extinction properties may not be realized, and when the number average molecular weight 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. When the content of the polyoxyalkylene resin 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, and examples thereof include ethyl acrylate, propyl acrylate, n-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, butyl methacrylate, methyl methacrylate, butyl methacrylate, and 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. When the content of the acrylic monomer polymer exceeds 99% by weight, the content of the polyoxyalkylene resin is too small, and the decomposition promoting effect may not be sufficiently obtained. A more preferable lower limit of the content of the acrylic monomer polymer is 50% by weight, and a more preferable 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 10% compressive strength is less than 1 MPa, the resin particles are destroyed at room temperature, and thus handling properties may be deteriorated when mixed with noble metal particles and molded. When the 10% compressive strength exceeds 1000 MPa, the molding machine screw may be damaged when it is mixed with noble metal particles and molded. In this specification, the 10% compressive strength means a pressure required to compress the heat extinguishing resin particles by 10% with respect to the particle diameter, for example, a micro hardness meter (manufactured by Fischer) or the like. 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 is 0.01 wt% or less exceeds 400 ° C., when degreasing is performed at 400 ° C. or less in order to improve 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 extinguisher resin particles, and mainly means carbon or the like.

The heat extinguishing resin particles may be heat extinguishing hollow resin particles having voids inside. The preferable lower limit of the hollowness ratio at 23 ° C. of the heat extinguishing hollow resin particles is 5%, and the preferable upper limit is 95%. When the hollow ratio is less than 5%, the effect of reducing combustion heat generation is not sufficient, and deformation or cracking occurs in the electrode obtained after molding. When the hollow ratio exceeds 95%, the particle strength of the heat extinguishing hollow resin particles decreases, and the particle shape cannot be maintained. In addition, the more preferable minimum of the said hollow ratio is 30%, a more preferable upper limit is 95%, and a still more preferable minimum is 50%.
In the present specification, the hollow ratio refers to the ratio of the volume of the hollow portion to the total volume of the heat extinguishing hollow resin fine particles, and is measured by using, for example, a porosimeter 2000 (manufactured by AMCO). Can do.

The lower limit of the average particle diameter of the heat extinguishing resin particles is 0.05 μm, and the upper limit is 10 μm.
If the average particle size of the heat extinguishing resin particles is less than 0.05 μm, the particle size is too small to obtain an electrode having sufficient voids, and the average particle size of the heat extinguishing resin particles is 10 μm. If it exceeds 1, contact between the noble metal particles does not become point contact, and the mechanical strength of the obtained electrode decreases. The minimum with a preferable average particle diameter of the said heat extinction resin particle is 0.07 micrometer, and a preferable upper limit is 4 micrometers.

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, but examples thereof include polymerizable unsaturated hydrocarbons such as (meth) acrylate, isocyanate groups, epoxy groups, hydrolyzable silyl groups, hydroxyl groups, and carboxyl groups. 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 the number average molecular weight 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- Examples include polyoxytetramethylene methacrylate (manufactured by NOF Corporation, BLEMMER 55PET-800).

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 may be insufficient. 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 some cases, 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 method for producing the heat extinguishing hollow resin fine particles is not particularly limited. For example, using the above-described monomer and hollowing agent, suspension polymerization method, emulsion polymerization method, dispersion polymerization method, soap-free polymerization method, miniemulsion A conventionally known polymerization method such as a polymerization method may be used.
In addition, as a method for producing the above heat extinguishing hollow resin fine particles, other polymerizable monomers are added to the polyoxyalkylene macromonomer having a functional group and the hollowing agent as required, and suspension polymerization is performed in a solvent. Is preferred.

Although it does not specifically limit as said hollowing agent, Since it is easy to handle when drying in a hollowing process, it is preferable that it is an organic solvent with a boiling point of -50-200 degreeC.

When an organic solvent having a boiling point of −50 to 200 ° C. is used as the hollowing agent, it is preferably mixed with the polyoxyalkylene macromonomer or mixed monomer to obtain a uniform solution and then suspension polymerization. As a result, the polyoxyalkylene macromonomer or the mixed monomer is phase-separated from the organic solvent as the polymerization proceeds, and particles in which the organic solvent is included in the polymer particles can be obtained. Thereafter, if the organic solvent contained in the obtained particles is evaporated and dried, a cavity is left in the particles, and heat extinguishing hollow particles can be obtained.

The organic solvent having a boiling point of −50 to 200 ° C. is not particularly limited. For example, butane, isobutane, pentane, isopentane, hexane, cyclohexane, heptane, octane, isooctane, toluene, ethyl acetate, methyl ethyl ketone, acetone, methylene chloride, Examples include chloroform and carbon tetrachloride. These may be used alone or in combination of two or more.

The medium for suspending the polyoxyalkylene macromonomer or mixed monomer and the hollowing agent is not particularly limited as long as it is incompatible with the polyoxyalkylene macromonomer, mixed monomer or hollowing agent. , Pure water, aqueous solution and the like.

The heat extinguishing hollow resin fine particles are prepared, for example, as an emulsion in which a water-containing hollowing agent is encapsulated in a polyoxyalkylene macromonomer or a mixed monomer of a polyoxyalkylene macromonomer and another polymerizable monomer. It can also be produced by a method comprising the steps of: dispersing the emulsion in water; and polymerizing the polyoxyalkylene macromonomer or the mixed monomer.

In such a production method, an emulsion (W / O emulsion) in which a hollowing agent containing water is encapsulated in the above polyoxyalkylene macromonomer or mixed monomer is dispersed in water to thereby form a three-layer emulsion. Since (W / O / W emulsion) is formed, particles in which a hollowing agent containing water is included in the polymer particles can be obtained more suitably. Then, by evaporating and drying the hollowing agent encapsulated in the obtained particles, voids remain in the particles, and heat extinguishing hollow resin fine particles can be produced. Each layer of the W / O / W emulsion may contain various additives for the purpose of stabilizing the emulsion.

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 slurry composition for forming an electrode of the present invention may further contain a binder resin.
The binder resin is not particularly limited, and examples thereof include acrylic resin, acetal resin, cellulose, urethane resin, vinyl acetate emulsion, SBR emulsion, EVA emulsion and the like.

The method for producing the electrode-forming slurry composition of the present invention is not particularly limited. For example, the noble metal particles, the heat extinguishing resin particles, and the dispersion solvent may be a ball mill, a blender mill, a three-roll roll, a hensil, a granulating mold. The method of mixing using various mixers, such as a dryer, etc. are mentioned.

By using the slurry composition for electrode formation of the present invention, for example, an air battery such as a zinc-air battery, an aluminum-air battery, a sugar-air battery, a fuel cell such as an oxyhydrogen fuel cell or a methanol fuel cell, an enzyme An oxygen electrode or an air electrode of an electrochemical device such as a sensor or an electrochemical sensor such as an oxygen sensor can be manufactured. Such an electrode is also one aspect of the present invention.

The electrode of the present invention includes, for example, Step 1 of preparing and drying the slurry composition for electrode formation of the present invention, Step 2 of forming a molded body by molding the slurry composition for electrode formation after drying, and It can be manufactured by a method having step 3 of sintering the molded body. Such an electrode manufacturing method is also one aspect of the present invention.

In the method for producing an electrode of the present invention, first, Step 1 of preparing and drying the slurry composition for electrode formation of the present invention is performed. In addition, after preparing the slurry composition for electrode formation of this invention, it dries and the process (granulation process) which produces the particle | grains which consist of a noble metal particle and a heat extinction resin particle is also contained in the process 1.

FIG. 1 is a schematic diagram showing a mixed state of noble metal particles and heat extinguishing resin particles after performing Step 1 of the present invention and granulating. In the figure, the case where platinum particles are used as the noble metal particles will be described.
As shown in FIG. 1, in the present invention, platinum particles 1 are bonded by point contact by adding and mixing heat extinguishing resin particles 2 having a predetermined average particle diameter, which will be described later, in a predetermined addition amount. It will come into contact. Thereby, in the subsequent sintering step, when the sintering is performed, the bonding between the platinum particles 1 becomes very strong. Therefore, the sintered metal obtained after sintering is excellent in mechanical strength. Become. Moreover, since the platinum 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 view showing a mixed state of platinum particles and a binder when granulation is performed by a conventional method in which a liquid binder is added to platinum particles as a raw material. As shown in FIG. 2, when a liquid binder is used, since the binder 3 is present in the form of a film around the platinum particles 1, the platinum particles 1 are less likely to contact each other and the voids between the platinum particles 1 are also reduced. . Therefore, the obtained metal sintered body has a low porosity and inferior mechanical strength.

In the above step 1, it is preferable to prepare a slurry composition for electrode formation by mixing noble metal particles and a dispersion in which heat extinguishing resin particles are dispersed in a dispersion solvent.
Since the dispersion is in a liquid state, it is easy to handle, and in Step 1, the precious 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 above dispersion liquid, the resin is not formed into a film as shown in FIG. 2, while noble metal particles (platinum particles) are in point contact as shown in FIG. 1, The noble metal particles are in a state of forming appropriate voids. Therefore, by using the above dispersion liquid, it is possible to enjoy the advantages of both the case of using a liquid binder and the case of using a solid powder binder.

Next, in the method for producing an electrode of the present invention, Step 2 of forming a molded body is performed by molding the slurry composition for electrode formation after drying.
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 electrode manufacturing method 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, the noble metal particles are mixed with the heat-extinguishing resin particles in a state of point contact with each other at an appropriate interval, and can be sintered at a low temperature for a short time. A sintered metal body having high mechanical strength and free from distortion and cracks can be obtained. When the porous metal sintered body thus obtained is used as an electrode, the pore diameter of the pore is appropriate, so that the oxide film and the solid electrolyte layer can penetrate into the pore. And the surface area of the interface between the oxide film and the electrolyte layer can be increased. As a result, electronic devices such as a fuel cell, an oxygen sensor, and a solid electrolytic capacitor having a large capacity and high reliability can be manufactured.

As a method for producing an electronic device using the electrode produced by the electrode production method of the present invention, a conventionally known method can be used.
For example, when manufacturing a solid electrolytic capacitor, a disc made of a fluororesin, a silicone rubber, a silicone resin, or the like is formed at the root of a lead wire for an anode drawn from a previously formed anode body made of a sintered metal. An insulating plate is arranged. 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 electrode composition slurry composition and electrode which can obtain the electrode which has sufficient mechanical strength, is excellent in electrical characteristics while having sufficient space | gap, and can aim at reduction of manufacturing cost. And the manufacturing method of an electrode 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.

(Example 1)
(Preparation of dispersion containing resin particles)
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 resin particle-containing dispersion.

(Example 2)
A resin particle-containing dispersion 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 resin particle-containing dispersion.

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 resin particle-containing dispersion was obtained in the same manner as in Example 1 except that the remaining emulsion suspension was added dropwise over 2 hours.

(Comparative Examples 1 and 2)
A resin particle-containing dispersion 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 By measuring the resin particles contained in the obtained dispersion liquid while using a differential scanning calorimeter (DSC-6200, manufactured by Seiko Instruments Inc.) at a heating rate of 5 ° C./min. The decomposition start temperature, the 50% by weight reduction temperature, the 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 and particle solid content concentration of the resin particles.

(Examples 5-9, Comparative Examples 3-6)
(Preparation of slurry)
According to the composition of Table 2, while stirring the platinum powder at 80 ° C., the resin particle-containing dispersion was dropped, and the resin particles were mixed with the platinum powder to prepare a slurry.

(Production of sintered body)
About the obtained slurry, the solvent water was volatilized and the platinum powder was granulated. The obtained granulated platinum 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 noble metal 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 1.0% by weight or less. ○, those exceeding 1.0% 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.

ADVANTAGE OF THE INVENTION According to this invention, the electrode composition slurry composition and electrode which can obtain the electrode which has sufficient mechanical strength, is excellent in electrical characteristics while having sufficient space | gap, and can aim at reduction of manufacturing cost. And the manufacturing method of an electrode can be provided.

It is sectional drawing which shows typically the mixed state of the platinum particle and heat extinction resin particle in this invention. It is sectional drawing which shows typically the mixed state of the platinum 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 Platinum 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 (10)

A slurry composition for electrode formation containing noble metal particles, heat extinguishing resin particles containing a polyoxyalkylene resin, and a dispersion solvent,
Containing the heat extinguishing resin particles in a solid content ratio of 0.01 to 20% by weight with respect to the noble metal particles;
The electrode forming slurry composition, wherein the heat extinguishing resin particles have an average particle diameter of 0.05 to 10 μm. The slurry composition for electrode formation according to claim 1, wherein the resin solid content is 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. The slurry composition for electrode formation according to claim 1 or 2, wherein the residue of the resin component becomes 0.01 wt% or less within 1 hour by further heating to a predetermined temperature of 200 to 400 ° C. object. 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 slurry composition for forming an electrode according to claim 1, 2, or 3. 5. The slurry composition for forming an electrode according to claim 1, wherein the polyoxyalkylene resin contains polyoxypropylene, polyoxyethylene, or polyoxytetramethylene. The slurry composition for forming an electrode according to claim 1, 2, 3, 4, or 5, wherein the polyoxyalkylene resin contains 5% by weight or more of polyoxypropylene. The slurry composition for electrode formation according to claim 1, 2, 3, 4, 5 or 6, wherein the dispersion solvent is water and / or alcohol. Furthermore, binder resin is contained, The slurry composition for electrode formation of Claim 1, 2, 3, 4, 5, 6 or 7 characterized by the above-mentioned. The electrode manufactured using the slurry composition for electrode formation of Claim 1, 2, 3, 4, 5, 6, 7 or 8. A step 1 of preparing and drying the electrode-forming slurry composition according to claim 1, 2, 3, 4, 5, 6, 7 or 8.
Step 2 of forming a molded body by molding the slurry composition for electrode formation after drying, and
The manufacturing method of the electrode characterized by having the process 3 which sinters the said molded object.

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