Method for producing porous body containing conductive polymer, solid electrolytic capacitor, and method for producing solid electrolytic capacitor

Abstract

The present invention relates to a method for producing a porous body containing a conductive polymer, the method comprising the following steps. An immersion step (A): an immersion step for immersing a part or the whole of a porous body having an oxide of a valve metal in a conductive polymer composition containing a conductive polymer and a solvent; a holding step (B) for taking out the porous body from the conductive polymer composition used in the previous immersion step and holding the porous body at a temperature equal to or lower than the boiling point of the solvent contained in the conductive polymer composition used in the previous immersion step for a predetermined holding time; and an impregnation step (C) for impregnating a portion or the whole of the porous body after the holding step (B) in a conductive polymer composition which is the same as or different from the conductive polymer composition used in the previous impregnation step and which contains a conductive polymer and a solvent.

Description

Technical Field

[0001] The present invention relates to a method for producing a porous body containing a conductive polymer, a solid electrolytic capacitor, and a method for producing a solid electrolyte capacitor. Background Art

[0002] In solid electrolyte capacitors such as aluminum electrolytic capacitors and tantalum capacitors, conductive polymers are used as materials for solid electrolyte layers. The capacitor element containing a porous body is immersed in a dispersion or solution of a conductive polymer (represented as a conductive polymer composition in the following description), and the conductive polymer composition impregnated in the pores of the porous body is dried, thereby forming these solid electrolyte layers as layers covering the surface of the pores (Patent Documents 1 to 3). In these technologies, in order to form a layer of solid electrolyte in the pores of the porous body, the porous body is immersed in the conductive polymer composition and dried at least twice.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-30046

[0006] Patent Document 2: Japanese Patent Application No. 2021-534576

[0007] Patent Document 3: Japanese Patent Application No. 2021-534579 Summary of the invention

[0008] In recent years, there has been a demand for efficient production of higher performance solid electrolyte capacitors, and therefore, it is required to increase the amount of conductive polymer filled into the pores of a porous body to increase the area of ​​the conductive polymer covering the pore surface.

[0009] However, in the techniques of Patent Documents 1 to 3, during the process of immersing and drying the porous body in the conductive polymer composition, the openings of the pores of the porous body are sometimes blocked by the film of the conductive polymer, and sometimes the amount of conductive polymer filled into the pores of the porous body is not sufficiently increased. Therefore, in the techniques of Patent Documents 1 to 3, it is necessary to repeatedly immerse and dry the porous body in the conductive polymer composition, and the overall process requires a lot of time, which has problems in efficiency.

[0010] In addition, in the techniques of Patent Documents 1 to 3, during the process of repeatedly immersing and drying the porous body in the conductive polymer composition, the conductive polymer film formed in the pores of the porous body may be redissolved in the conductive polymer composition, or the film may be repeatedly swollen and shrunk and peeled off from the porous body. Therefore, even if the porous body is repeatedly immersed and dried in the conductive polymer composition, the filling amount of the conductive polymer in the pores of the porous body may not be sufficiently increased.

[0011] Therefore, in the techniques of Patent Documents 1 to 3, the manufacturing efficiency of the solid electrolytic capacitor cannot be improved, and the dielectric loss tangent is likely to increase.

[0012] An object of the present invention is to provide a method for efficiently producing a porous body containing a conductive polymer that can provide a solid electrolytic capacitor having a small dielectric loss tangent.

[0013] According to the present invention, there are provided the following method for producing a porous body containing a conductive polymer.

[0014] 1. A method for producing a porous body containing a conductive polymer, comprising the following steps.

[0015] An immersion step (A): an immersion step of immersing a part or the whole of the porous body having an oxide of a valve metal in a conductive polymer composition containing a conductive polymer and a solvent;

[0016] Holding step (B): a step of taking the porous body out of the conductive polymer composition used in the previous immersion step and holding it for a predetermined holding time at a temperature below the boiling point of the solvent contained in the conductive polymer composition used in the previous immersion step;

[0017] Impregnation step (C): a step of immersing a part or the whole of the porous body after the holding step (B) in a conductive polymer composition containing a conductive polymer and a solvent which is the same as or different from the conductive polymer composition used in the previous impregnation step.

[0018] 2. The method for producing a porous body containing a conductive polymer according to 1, comprising the step of immersing a part of the porous body in the conductive polymer composition and maintaining the immersion state, and then immersing a non-impregnated part of the porous body in the conductive polymer composition.

[0019] 3. The method for producing a conductive polymer-containing porous body according to 1 or 2, wherein in the step (B), the holding time is 1 second or longer and less than 10 minutes.

[0020] 4. The method for producing a porous body containing a conductive polymer according to any one of 1 to 3, wherein the step (B) and the step (C) are repeated a plurality of times.

[0021] 5. The method for producing a porous body containing a conductive polymer according to any one of 1 to 4, wherein the conductive polymer is at least one selected from the group consisting of polyaniline, polyaniline derivatives, polythiophene, polythiophene derivatives, polypyrrole and polypyrrole derivatives.

[0022] 6. The method for producing a porous body containing a conductive polymer according to any one of 1 to 5, wherein the conductive polymer is a polyaniline composite in which polyaniline is doped with a proton donor.

[0023] 7. The method for producing a conductive polymer-containing porous body according to any one of 1 to 6, wherein the conductive polymer composition further contains a phenolic compound.

[0024] 8. The method for producing a conductive polymer-containing porous body according to any one of 1 to 7, wherein the conductive polymer composition further contains a heat stabilizer.

[0025] 9. A porous body containing a conductive polymer, which is obtained by the method for producing a porous body containing a conductive polymer according to any one of 1 to 8.

[0026] 10. A method for manufacturing a solid electrolytic capacitor, comprising the following steps.

[0027] An impregnation step (A): an impregnation step of immersing a part or the whole of an anode body, which is a porous body containing a valve metal and having a surface containing an oxide of a valve metal, in a conductive polymer composition containing a conductive polymer and a solvent;

[0028] Holding step (B): a step of taking the anode body out of the conductive polymer composition used in the previous impregnation step and holding it for a predetermined holding time at a temperature below the boiling point of the solvent contained in the conductive polymer composition used in the previous impregnation step;

[0029] An immersion step (C): an immersion step of immersing a part or the whole of the anode body after the holding step (B) in a conductive polymer composition containing a conductive polymer and a solvent which is the same as or different from the conductive polymer composition used in the previous immersion step;

[0030] Drying step (D): a step of taking out the anode body from the conductive polymer composition and drying it at a temperature exceeding the boiling point of the solvent to form a solid electrolyte layer containing a conductive polymer on the anode body.

[0031] 11. The method for producing a solid electrolytic capacitor according to 10, further comprising the step of immersing the anode body having the solid electrolyte layer formed thereon in a conductive polymer composition comprising a conductive polymer and a solvent, and then drying the composition to form an outer coating layer.

[0032] 12. A solid electrolytic capacitor obtained by the method for manufacturing a solid electrolytic capacitor according to 10 or 11.

[0033] 13. A porous body with a solid electrolyte layer, comprising an oxide of a valve metal, the porous body comprising:

[0034] a solid electrolyte layer formed inside the pores of the porous body and containing polyaniline; and

[0035] A solid electrolyte layer is applied to the outside of the porous body and contains polyaniline.

[0036] 14. A solid electrolytic capacitor comprising the porous body with a solid electrolyte layer as described in 13, wherein an equivalent series resistance (ESR) of the solid electrolytic capacitor is 17 mΩ or less.

[0037] According to the present invention, it is possible to provide a method for efficiently producing a porous body containing a conductive polymer, which can provide a solid electrolytic capacitor having a small dielectric loss tangent. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a process diagram schematically showing a method for producing a conductive polymer-containing porous body according to the present embodiment.

[0039] Figure 2 This is a process diagram schematically showing a conventional method for producing a porous body containing a conductive polymer. DETAILED DESCRIPTION

[0040] [Method for producing a porous body containing a conductive polymer]

[0041] The method for producing a conductive polymer-containing porous body according to the present embodiment includes the following steps.

[0042] An immersion step (A): an immersion step of immersing a part or the whole of the porous body having an oxide of a valve metal in a conductive polymer composition containing a conductive polymer and a solvent;

[0043] Holding step (B): a step of taking the porous body out of the conductive polymer composition used in the previous immersion step and holding it for a predetermined holding time at a temperature below the boiling point of the solvent contained in the conductive polymer composition used in the previous immersion step;

[0044] Impregnation step (C): a step of immersing a part or the whole of the porous body after the holding step (B) in a conductive polymer composition containing a conductive polymer and a solvent which is the same as or different from the conductive polymer composition used in the previous impregnation step.

[0045] exist Figure 1 2 is a process diagram schematically showing a method for producing a porous body containing a conductive polymer according to the present embodiment.

[0046] exist Figure 2 2 shows a process diagram schematically describing a conventional method for producing a porous body containing a conductive polymer.

[0047] When a porous body is immersed in the conductive polymer composition, a liquid film of the conductive polymer composition may be formed at the openings of the pores while air flows into the pores, thereby achieving a liquid-sealed state in which air is sealed inside the pores of the porous body.

[0048] If the porous body having pores in a liquid-sealed state is lifted out of the conductive polymer composition and dried as in the conventional method (refer to Figure 2 (b)), the solvent component evaporates from the liquid film and solidifies to form a film composed of a conductive polymer. Therefore, when the porous body is immersed in the conductive polymer composition again (refer to Figure 2 (c)) The conductive polymer film at the pore openings prevents the conductive polymer composition from penetrating into the pores. Therefore, it is difficult to increase the amount of the conductive polymer composition filled into the pores.

[0049] Here, the “drying” in the conventional art is generally performed at a temperature higher than the boiling point of the solvent contained in the conductive polymer composition.

[0050] In the production method of this embodiment, the porous body 10 immersed in the conductive polymer composition 11 is temporarily taken out from the conductive polymer composition 11 and exposed to the air, and the porous body is kept at a temperature below the boiling point of the solvent contained in the conductive polymer composition 11 while the entire porous body is exposed to the space outside the conductive polymer composition 11 (see Figure 1 (b)). As a result, the liquid film formed at the opening of the pore disappears, the liquid-sealed state formed in the porous body 10 is eliminated, and the air sealed inside the pore is discharged. Therefore, when the porous body 10 is immersed in the conductive polymer composition 11 again (refer to Figure 1 According to (c)), the conductive polymer composition 11 can be impregnated deep into the pores of the porous body 10. In addition, the number of times of immersion in the conductive polymer composition 11 can be reduced.

[0051] By repeating the above steps (B) and (C), even if the porous body 10 is temporarily in a liquid-sealed state, in the next step (B) (see Figure 1 Since the liquid-sealed state of (b)) is eliminated and air is discharged from the pores, the conductive polymer composition can be impregnated until a sufficient thickness of the layer containing the conductive polymer is achieved.

[0052] In addition, as described later, by applying this method to the manufacture of solid electrolytic capacitors, a solid electrolyte layer containing a conductive polymer can be formed deep into the pores, thereby increasing the coating area of ​​the conductive polymer on the pore surface of the porous body, and efficiently manufacturing solid electrolytic capacitors with a small dielectric loss tangent and low loss.

[0053] This is presumably because a conductive polymer film (solid electrolyte layer) is densely formed on the pore surfaces of the valve metal of the solid electrolytic capacitor, thereby improving the conductivity inside the capacitor when voltage is applied, and achieving a low resistance state.

[0054] Furthermore, by applying this method to the production of a solid electrolytic capacitor, the coating area of ​​the pore surfaces of the porous body formed of the conductive polymer increases, so that a solid electrolytic capacitor having a small equivalent series resistance (ESR) and a large electrostatic capacitance can be produced.

[0055] In the present specification, “the boiling point of the solvent” refers to the boiling point of the solvent contained in the conductive polymer composition. When the conductive polymer composition contains a plurality of solvents, it refers to the boiling point of the solvent having the lowest boiling point among them.

[0056] Hereinafter, a method for producing the conductive polymer-containing porous body of this embodiment will be described.

[0057] (Process (A))

[0058] First, a part or the whole of the porous body having an oxide of a valve metal is immersed in a conductive polymer composition containing a conductive polymer and a solvent (immersion step).

[0059] As a result, the conductive polymer composition is impregnated into the pores of the porous body (sometimes simply referred to as “porous body” in the following description) having the oxide of the valve metal.

[0060] Examples of the valve metal include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony, and aluminum and tantalum are preferred. Examples of the valve metal oxide include oxides of these metals.

[0061] Examples of the porous body having a valve metal oxide include a porous body containing only a valve metal oxide and a porous body having a part of the structure of a valve metal oxide. In the latter case, the valve metal oxide is preferably present on the surface of the porous body.

[0062] The porous body is a material having pores, and preferably has a large number of pores having a diameter of about 1 nm to 10 μm on its surface.

[0063] The shape of the porous body is not particularly limited, and it may be, for example, a formed body or a film (foil) and have a certain thickness.

[0064] Examples of the porous body include a molded body containing only metal oxides (e.g., a sphere containing aluminum oxide having fine pores (alumina sphere)). In addition, examples include a film (foil) containing metal oxides (e.g., a film (foil) containing aluminum having etched pores by roughening and aluminum oxide formed on the surface thereof) (anode material for aluminum electrolytic capacitors); and a film containing a sintered body formed of tantalum particles and tantalum pentoxide formed on the surface thereof (anode material for tantalum capacitors).

[0065] The conductive polymer composition used in step (A) contains (a) a conductive polymer and (b) a solvent. Each component contained in the conductive polymer composition will be described later.

[0066] The method for impregnating the porous body having a valve metal oxide in the conductive polymer composition is not particularly limited. The entire porous body may be immersed in the conductive polymer composition in a single operation, or the porous body may be immersed in the conductive polymer composition stepwise or continuously.

[0067] "Immersing in stages" means moving the porous body in multiple times and immersing the porous body in the conductive polymer composition in stages. That is, "immersing in stages" means performing an immersion action in stages, and taking out the conductive polymer composition in step (B) after a series of immersion actions in stages. As an example of "immersing in stages" by a single input action, for example, repeatedly performing: maintaining a state of immersing the porous body in the conductive polymer composition from the lower end to a predetermined distance, then maintaining a state of immersing the porous body to the next predetermined distance, and finally immersing the porous body to the upper end.

[0068] "Continuously impregnating" means that the porous body is continuously moved at a predetermined speed and gradually impregnated with the conductive polymer composition. As an example of "continuously impregnating" by a single insertion operation, for example, the conductive polymer composition is impregnated from the lower end of the porous body to a predetermined distance at a certain speed, thereby impregnating the porous body to the upper end.

[0069] By immersing the porous body in the conductive polymer composition stepwise or continuously, the conductive polymer can be smoothly impregnated into the pores of the porous body.

[0070] When the porous body is impregnated in stages, the first impregnation is preferably performed on the porous body from the lower end e (refer to Figure 1 (b)) is the height h in the immersion direction D of the porous body (refer to Figure 1 The immersion is performed to a height position of 10 to 70% of the height of (b)), and more preferably to a height position of 15 to 50%.

[0071] When the porous body is impregnated in stages, the second impregnation is preferably performed on the porous body from the lower end e (refer to Figure 1 (b)) is the height h in the immersion direction D of the porous body (refer to Figure 1 The immersion is performed up to a height position of 20 to 90%, and more preferably up to a height position of 30 to 80%, of (b)).

[0072] When the entire porous body is immersed in the conductive polymer composition by a single insertion operation, the time for which the porous body is kept in the conductive polymer composition (hereinafter referred to as the immersion time) is usually 1 to 30 minutes, preferably 1 to 10 minutes.

[0073] When the porous body is moved several times and immersed in the conductive polymer composition in stages, the porous body is first immersed in the conductive polymer composition from the bottom to a predetermined height and maintained immersed for, for example, 1 to 30 minutes, preferably 1 to 10 minutes.

[0074] Next, the porous body is moved to further immerse a part of the non-impregnated portion in the conductive polymer composition, and the immersed state is maintained for, for example, 1 to 20 minutes, preferably 1 to 10 minutes.

[0075] The immersion times when the entire porous body is immersed in the conductive polymer composition by a single injection operation, for example, the first immersion (step (A) described later), the second immersion (step (C) described later for the first time), and the third immersion (step (C) for the second time) may be the same, may be increased sequentially, or may be decreased sequentially.

[0076] When the porous body is immersed in the conductive polymer composition in stages by a single injection operation (step (A) or step (C)), the immersion time for immersing and maintaining the porous body in each stage may be the same in each step, may be increased in sequence, or may be decreased. From the perspective of manufacturing efficiency, it is preferred to decrease the immersion time in sequence. By repeating this operation, the entire porous body is finally immersed in the conductive polymer composition.

[0077] When the porous body is immersed in the conductive polymer composition in stages, the total immersion time in each immersion stage for each feeding operation (step (A) or each step (C)), that is, the immersion time in one feeding operation, may be increased or decreased sequentially.

[0078] The temperature at which the porous body is impregnated with the conductive polymer composition is not particularly limited, but is usually room temperature.

[0079] (Process (B))

[0080] Next, the porous body is taken out from the conductive polymer composition used in the previous impregnation step and is held for a predetermined holding time at a temperature not higher than the boiling point of the solvent contained in the conductive polymer composition used in the previous impregnation step (holding step).

[0081] As a result, the liquid film formed at the openings of the pores of the porous body disappears, and the liquid-sealed state is eliminated.

[0082] For example, when step (B) is performed immediately after step (A), the "conductive polymer composition used in the previous impregnation step" means the conductive polymer composition used in step (A) performed immediately before step (B). Also, for example, when step (B) is performed immediately after step (C), the "conductive polymer composition used in the previous impregnation step" means the conductive polymer composition used in step (C) performed immediately before step (B).

[0083] In the following description of step (B), “the conductive polymer composition used in the previous impregnation step” may be simply referred to as “the conductive polymer composition”.

[0084] The space to which the porous body taken out from the conductive polymer composition is exposed, that is, the "space outside the conductive polymer composition", is preferably in the air for the sake of convenience.

[0085] The porous body taken out from the conductive polymer composition may be kept at a temperature below the boiling point of the solvent contained in the conductive polymer composition used in the previous immersion step, for example, in air or in a predetermined gas flow atmosphere such as argon or nitrogen.

[0086] The temperature of the space in which the porous body taken out from the conductive polymer composition is maintained is not particularly limited as long as it is below the boiling point of the solvent contained in the conductive polymer composition used in the previous impregnation step. From the viewpoint of smoothly eliminating the liquid-sealed state of the porous body, it is preferably at least 10°C lower than the boiling point of the solvent contained in the conductive polymer composition used in the previous impregnation step, preferably at least 15°C lower, and more preferably at least 20°C lower.

[0087] The temperature of the space in which the porous body taken out from the conductive polymer composition is kept may be, for example, 0 to 40°C, or 10 to 30°C.

[0088] When the temperature is within the above-mentioned temperature range, it is easy to suppress the solidification of the liquid film formed at the pore openings of the porous body.

[0089] The pressure of the space in which the porous body taken out from the conductive polymer composition is held is not particularly limited, but is usually atmospheric pressure, for example, 1 to 760 mmHg, or 300 to 760 mmHg.

[0090] When the pressure is within the above-mentioned pressure range, the liquid-sealed state formed in the porous body can be eliminated smoothly.

[0091] The holding time of the porous body taken out from the conductive polymer composition is not particularly limited, and may be 1 second or more, 5 seconds or more, or 10 seconds or more, and may be less than 10 minutes, 7 minutes or less, 5 minutes or less, or 3 minutes or less. From the viewpoint of manufacturing efficiency and the viewpoint of suppressing the volatilization of the solvent from the liquid film, the suitable holding time is 1 minute or less, or 30 seconds or less.

[0092] (Process (C))

[0093] Next, a part or the whole of the porous body after the holding step (B) is immersed in a conductive polymer composition containing a conductive polymer and a solvent which is the same as or different from the conductive polymer composition used in the previous immersion step (immersion step).

[0094] This allows the conductive polymer composition to penetrate deep into the porous body in which the liquid-sealed state has been eliminated, thereby achieving a state in which the conductive polymer composition is highly filled in the pores of the porous body.

[0095] The conductive polymer composition with which the porous body is impregnated in step (C) may be the same as the conductive polymer composition used in step (A) or different from the conductive polymer composition used in step (A). In addition, when step (B) and step (C) are repeated as described later, the conductive polymer composition with which the porous body is impregnated in the previous step (C) may be the same as the conductive polymer composition used in the previous step (C) or different from the conductive polymer composition used in the previous step (C).

[0096] Here, “the conductive polymer compositions are different” means that the conductive polymer and the solvent contained in the conductive polymer composition are of different types and their blending amounts are different (that is, the concentrations of the conductive polymer are different).

[0097] The porous body can be immersed in the conductive polymer composition by a single insertion operation similarly to the step (A).

[0098] Alternatively, for example, the porous body may be immersed in the conductive polymer composition stepwise or continuously in the same manner as described in step (A).

[0099] The appropriate range of the immersion time in each case and the appropriate range of the temperature at which the porous body is impregnated with the conductive polymer composition are the same as those described in the step (A).

[0100] When the porous body is impregnated stepwise, the preferred range of the height h of the porous body in the immersion direction D at each stage is the same as that described in the step (A).

[0101] The method for impregnating the porous body in the conductive polymer composition in the step (A) and the method for impregnating the porous body in the conductive polymer composition in the step (C) may be the same as or different from each other.

[0102] For example, in step (A), when the porous body is immersed in the conductive polymer composition in stages, in step (C), the entire porous body can be immersed in the conductive polymer composition by a single insertion operation, the porous body can be immersed in the conductive polymer composition continuously, or the porous body can be immersed in the conductive polymer composition in stages.

[0103] After step (C), the cycle of step (B) and step (C) may be repeated multiple times. For example, the cycle of step (B) and step (C) may be repeated 2 to 10 times in total.

[0104] When the cycle of step (B) and step (C) is repeated a plurality of times, the conductive polymer composition with which the porous body is impregnated in each step (C) may be the same as or different from the conductive polymer composition used in the previous step (C).

[0105] (Process (D))

[0106] Step (D) is an optional step, which is a drying step for volatilizing the solvent contained in the conductive polymer composition from the porous body after step (C) to promote the fixation of the conductive polymer to the porous body. Here, "drying" is different from step (B) and refers to a solvent volatilization treatment performed at a temperature higher than the boiling point of the solvent in the conductive polymer composition.

[0107] Here, when the conductive polymer composition contains a plurality of solvents, “a temperature higher than the boiling point of the solvent in the conductive polymer composition” means the boiling point of the solvent having the highest boiling point among these solvents.

[0108] The drying temperature of the porous body containing the conductive polymer composition is a temperature higher than the boiling point of the solvent in the conductive polymer composition, and should be appropriately determined depending on the type of solvent used, and is usually 30 to 200° C., preferably 100 to 180° C. The drying time is usually 10 to 120 minutes, preferably 30 to 90 minutes.

[0109] By drying the porous body in step (D), a porous body containing a conductive polymer in which a solid electrolyte layer containing a conductive polymer is more firmly fixed inside the pores and on the surface of the porous body can be obtained.

[0110] The conductive polymer-containing porous body refers to a porous body containing a conductive polymer, and specifically refers to a porous body containing a solid electrolyte (solid electrolyte layer) containing a conductive polymer inside pores or on the surface of the porous body.

[0111] Examples of porous bodies containing conductive polymers include spheres of aluminum oxide containing a solid electrolyte containing a conductive polymer (alumina spheres), anode materials for aluminum electrolytic capacitors formed with a solid electrolyte containing a conductive polymer (solid electrolyte layer), and anode materials for tantalum capacitors (anode bodies containing valve metals and oxides thereof).

[0112] Each component contained in the conductive polymer composition used in this embodiment will be described in detail.

[0113] (a) Conductive polymer

[0114] As the conductive polymer (component (a)), polyaniline, polythiophene, polypyrrole and derivatives thereof may be mentioned. These may have a substituent or may not have a substituent. These may be used alone or in combination of two or more.

[0115] As the conductive polymer, polyaniline is preferred.

[0116] The weight average molecular weight of polyaniline is preferably 10,000 or more, more preferably 20,000 or more, further preferably 30,000 or more and 1,000,000 or less, further preferably 40,000 or more and 1,000,000 or less, particularly preferably 52,000 or more and 1,000,000 or less.

[0117] When a conductive polymer is used in a solid electrolyte layer of a solid electrolytic capacitor, for example, the larger the molecular weight of the conductive polymer, the more preferred it is from the viewpoint of being able to increase the strength of the resulting electrolyte layer. On the other hand, if the molecular weight is large, the viscosity becomes high, so it is sometimes difficult to penetrate into the pores of a porous body.

[0118] The molecular weight of polyaniline is measured by the method described in Examples.

[0119] From the viewpoint of versatility and economic efficiency, the polyaniline is preferably unsubstituted polyaniline.

[0120] When the substituent has a substituent, for example, a straight-chain or branched hydrocarbon group such as methyl, ethyl, hexyl, octyl, etc.; an alkoxy group such as methoxy, ethoxy, etc.; an aryloxy group such as phenoxy, etc.; a trifluoromethyl group (-CF 3 alkyl) and other halogenated hydrocarbons.

[0121] In one embodiment of the present invention, the conductive polymer is preferably a polyaniline composite in which a proton donor is doped into polyaniline. By using the polyaniline composite, the solubility in a solvent is improved.

[0122] The doping of proton donors in polyaniline can be confirmed by ultraviolet-visible-near-infrared spectroscopy and X-ray photoelectron spectroscopy.

[0123] The proton donor can be used without particular limitation as long as it has acidity sufficient to form a carrier of polyaniline.

[0124] Examples of the proton donor include Bronsted acids or salts thereof, preferably organic acids or salts thereof, and more preferably a proton donor represented by the following formula (I).

[0125] M(XARn)m(I)

[0126] M in formula (I) is a hydrogen atom, an organic free radical or an inorganic free radical.

[0127] Examples of the organic radical include pyridinium, imidazolium, and anilinium groups, and examples of the inorganic radical include lithium, sodium, potassium, cesium, ammonium, calcium, magnesium, and iron.

[0128] X in formula (I) is an anionic group, for example -SO 3 - Base, -PO 3 2- Base, -PO 4 (OH) - Base, -OPO 3 2- Base, -OPO 2 (OH) - -COO - Group, preferably -SO 3 - base.

[0129] A in formula (I) is a substituted or unsubstituted hydrocarbon group (having, for example, 1 to 20 carbon atoms).

[0130] The hydrocarbon group is a chain or cyclic saturated aliphatic hydrocarbon group, a chain or cyclic unsaturated aliphatic hydrocarbon group, or an aromatic hydrocarbon group.

[0131] As chain saturated aliphatic hydrocarbon groups, linear or branched alkyl groups (for example, the number of carbon atoms is 1 to 20) can be mentioned. As cyclic saturated aliphatic hydrocarbon groups, cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl (for example, the number of carbon atoms is 3 to 20) can be mentioned. The cyclic saturated aliphatic hydrocarbon group can be formed by condensing multiple cyclic saturated aliphatic hydrocarbon groups. For example, norbornyl, adamantyl, condensed adamantyl, etc. can be mentioned. As chain unsaturated aliphatic hydrocarbon groups (for example, the number of carbon atoms is 2 to 20), linear or branched alkenyl groups can be mentioned. As cyclic unsaturated aliphatic hydrocarbons (for example, the number of carbon atoms is 3 to 20), cyclic alkenyl groups can be mentioned. As aromatic hydrocarbon groups (for example, the number of carbon atoms is 6 to 20), phenyl, naphthyl, anthracenyl, etc. can be mentioned.

[0132] When A is a substituted hydrocarbon group, the substituent is an alkyl group (e.g., having 1 to 20 carbon atoms), a cycloalkyl group (e.g., having 3 to 20 carbon atoms), a vinyl group, an allyl group, an aryl group (e.g., having 6 to 20 carbon atoms), an alkoxy group (e.g., having 1 to 20 carbon atoms), a halogen atom, a hydroxyl group, an amino group, an imino group, a nitro group, a silyl group or a group containing an ester bond.

[0133] In formula (I), R is bonded to A and is -H, -R 1 、-OR 1 、-COR 1 、-COOR1 、-(C=O)-(COR 1 ), or -(C=O)-(COOR 1 ) is a substituent shown in FIG. 1 is a hydrocarbon group which may contain a substituent, a silyl group, an alkylsilyl group, -(R 2 O)xR 3 Base, or - (OSiR 3 2 )x-OR 3 Base. R 2 is an alkylene group, R 3 is a hydrocarbon group, and x is an integer greater than 1. When x is greater than 2, a plurality of R 2 Each can be the same or different. 3 Each may be the same or different.

[0134] As R 1 Examples of the hydrocarbon group (having 1 to 20 carbon atoms) include methyl, ethyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, pentadecyl, eicosyl, etc. The hydrocarbon group may be linear or branched.

[0135] The substituent of the hydrocarbon group is an alkyl group (e.g., having 1 to 20 carbon atoms), a cycloalkyl group (e.g., having 3 to 20 carbon atoms), a vinyl group, an allyl group, an aryl group (e.g., having 6 to 20 carbon atoms), an alkoxy group (e.g., having 1 to 20 carbon atoms), a halogen group, a hydroxyl group, an amino group, an imino group, a nitro group, or a group containing an ester bond. 3 The hydrocarbon group also has 1 same.

[0136] As R 2 Examples of the alkylene group (having 1 to 20 carbon atoms) include a methylene group, an ethylene group, and a propylene group.

[0137] In formula (I), n is an integer greater than or equal to 1. When n is greater than or equal to 2, a plurality of Rs may be the same or different.

[0138] In the formula (I), m is the valence of M / the valence of X.

[0139] The compound represented by formula (I) is preferably a dialkylbenzenesulfonic acid, a dialkylnaphthalenesulfonic acid, or a compound having two or more ester bonds.

[0140] The compound containing two or more ester bonds is more preferably a sulfophthalate ester or a compound represented by the following formula (II).

[0141]

Chemical formula 1

[0142]

[0143] In formula (II), M and X are the same as those in formula (I). X is preferably -SO 3 - base.

[0144] R 4 , R 5 and R 6 are each independently a hydrogen atom, a hydrocarbon group or R 9 3 Si-based. 3 R 9 Each is independently a hydrocarbon group.

[0145] As R 4 , R 5 and R 6 In the case of a hydrocarbon group, the hydrocarbon group includes a linear or branched alkyl group having 1 to 24 carbon atoms, an aryl group containing an aromatic ring (having, for example, 6 to 20 carbon atoms), and an alkylaryl group (having, for example, 7 to 20 carbon atoms).

[0146] As R 9 The hydrocarbon group, with R 4 , R 5 and R 6 The same situation.

[0147] R of formula (II) 7 and R 8 Each independently is a hydrocarbon group or -(R 10 O) q -R 11 Base. R 10 is a hydrocarbon group or a silylene group, R 11 is a hydrogen atom, a hydrocarbon group or R 12 3 Si-, q is an integer greater than or equal to 1. 3 R 12 Each is independently a hydrocarbon group.

[0148] As R 7 and R 8 The hydrocarbon group in the case of a hydrocarbon group includes a linear or branched alkyl group having 1 to 24 carbon atoms, preferably 4 or more carbon atoms, an aryl group containing an aromatic ring (for example, 6 to 20 carbon atoms), an alkylaryl group (for example, 7 to 20 carbon atoms), etc. Specific examples include butyl, pentyl, hexyl, octyl, decyl, etc., all of which are linear or branched.

[0149] As R 7 and R 8 R 10The hydrocarbon group in the case of a hydrocarbon group is, for example, a linear or branched alkylene group having 1 to 24 carbon atoms, an arylene group containing an aromatic ring (having, for example, 6 to 20 carbon atoms), an alkylarylene group (having, for example, 7 to 20 carbon atoms), or an arylalkylene group (having, for example, 7 to 20 carbon atoms). 7 and R 8 R 11 and R 12 When it is a hydrocarbon group, the hydrocarbon group and R 4 , R 5 and R 6 The same is true for the case where q is preferably 1 to 10.

[0150] As R 7 and R 8 =R 10 O) q -R 11 Specific examples of the compound represented by formula (II) are two compounds represented by the following formulae.

[0151]

Chemical formula 2

[0152]

[0153] (Wherein, X is the same as in formula (I).)

[0154] The compound represented by the above formula (II) is more preferably a sulfosuccinic acid derivative represented by the following formula (III).

[0155]

Chemical formula 3

[0156]

[0157] In formula (III), M is the same as in formula (I). m' is the valence of M.

[0158] R 13 and R 14 Each independently is a hydrocarbon group or -(R 15 O) r -R 16 Base. R 15 is a hydrocarbon group or a silylene group, R 16 is a hydrogen atom, a hydrocarbon group or R 17 3 Si-group, r is an integer greater than 1. 3 R 17 Each independently represents a hydrocarbon group. When r is 2 or more, a plurality of R 15 Each may be the same or different.

[0159] As R 13 and R 14 When it is a hydrocarbon group, the hydrocarbon group and R 7and R 8 same.

[0160] R 13 and R 14 In, as R 15 When it is a hydrocarbon group, the hydrocarbon group is the same as the above R 10 In addition, R 13 and R 14 In, as R 16 and R 17 When it is a hydrocarbon group, the hydrocarbon group is the same as the above R 4 , R 5 and R 6 same.

[0161] r is preferably 1-10.

[0162] As R 13 and R 14 =R 15 O) r -R 16 A specific example of base time, and R 7 and R 8 - (R 10 O) q -R 11 same.

[0163] As R 13 and R 14 The hydrocarbon group, with R 7 and R 8 Among them, butyl, hexyl, 2-ethylhexyl and decyl are preferred.

[0164] As the compound represented by formula (I), di(2-ethylhexyl)sulfosuccinic acid and sodium di(2-ethylhexyl)sulfosuccinate are preferred.

[0165] It is known that the above-mentioned proton donor can control the conductivity and solubility in a solvent of a polyaniline composite by changing its structure (Japanese Patent No. 3384566). In this embodiment, the optimal proton donor can be selected according to the required properties for each application.

[0166] The doping rate of the proton donor to polyaniline is preferably 0.30 to 0.65, more preferably 0.32 to 0.60, further preferably 0.33 to 0.57, and particularly preferably 0.34 to 0.55. Generally, if the doping rate is 0.30 or more, the solubility of the polyaniline composite in an organic solvent becomes sufficient.

[0167] The doping rate is defined by (the number of moles of proton donor doped in polyaniline) / (the number of moles of monomer units of polyaniline). For example, a doping rate of 0.5 for a polyaniline composite containing unsubstituted polyaniline and a proton donor means that one proton donor is doped for every two monomer unit molecules of polyaniline.

[0168] It should be noted that the doping rate can be calculated as long as the molar number of the proton donor and the monomer unit of polyaniline in the polyaniline composite can be measured. For example, when the proton donor is an organic sulfonic acid, the molar number of sulfur atoms from the proton donor and the molar number of nitrogen atoms from the monomer unit of polyaniline are quantified by organic element analysis, and the ratio of these values ​​is taken to calculate the doping rate.

[0169] The polyaniline composite preferably contains unsubstituted polyaniline and sulfonic acid as a proton donor, and satisfies the following formula (1).

[0170] 0.32≤S 5 / N 5 ≤0.60 (1)

[0171] (Where S 5 is the total number of moles of sulfur atoms contained in the polyaniline composite, N 5 It is the total number of moles of nitrogen atoms contained in the polyaniline composite.

[0172] It should be noted that the molar numbers of the nitrogen atoms and sulfur atoms are values ​​measured by, for example, organic element analysis.

[0173] The method for producing the soluble conductive polymer of the above embodiment is not particularly limited, and the soluble conductive polymer can be produced, for example, by the method for producing a soluble conductive polymer of the embodiment described below.

[0174] For example, the proton donor, the aniline corresponding to the polyaniline, and a surfactant (e.g., a nonionic emulsifier) ​​as required are dissolved in a water-immiscible organic solvent (e.g., a hydrocarbon solvent (preferably toluene or xylene), an acidic aqueous solution (e.g., an aqueous phosphoric acid solution) is added thereto, the reaction liquid having two liquid phases of the water-immiscible organic solvent and water is stirred, and a polymerization initiator (e.g., ammonium persulfate) is added to carry out polymerization.

[0175] After polymerization, the water-immiscible organic solvent is allowed to stand for phase separation, thereby obtaining a water-immiscible organic solvent solution of the polyaniline composite. The solution is transferred to an evaporator, and the volatile components are evaporated to obtain a polyaniline composite (protonated polyaniline).

[0176] (b) Solvent

[0177] The solvent (component (b)) is not particularly limited as long as it can dissolve or disperse the conductive polymer. The solvent (component (b)) is particularly preferably a solvent that can dissolve the conductive polymer. However, components (c) to (e) described later are not included. The solvent is preferably an organic solvent. For example, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols, ketones, ethers, and esters can be mentioned. These can be used alone or in combination of two or more.

[0178] The organic solvent may be a water-soluble organic solvent, or may be an organic solvent substantially immiscible with water (a water-immiscible organic solvent).

[0179] As the water-soluble organic solvent, a highly polar organic solvent can be used, which can be a protic polar solvent or an aprotic polar solvent. For example, alcohols such as methanol, ethanol, isopropanol, 1-propanol, 1-ethoxy-2-propanol, 2-ethoxy-1-propanol, 1-butanol, 2-butanol, 2-pentanol, benzyl alcohol, and alkoxy alcohols (such as 1-methoxy-2-propanol, 3-methoxy-1-butanol, and 3-methoxy-3-methylbutanol); ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ethers such as tetrahydrofuran, 4-methyltetrahydropyran, dioxane, diethyl ether, and ethylene glycol monotert-butyl ether; and aprotic polar solvents such as N-methylpyrrolidone.

[0180] As the water-immiscible organic solvent, a low-polarity organic solvent can be used, for example, hydrocarbon solvents such as hexane, benzene, toluene, xylene, ethylbenzene, tetralin, etc.; halogen-containing solvents such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, tetrachloroethane, etc.; ester solvents such as ethyl acetate, isobutyl acetate, n-butyl acetate, ethyl lactate, methyl lactate, etc.; ketone solvents such as methyl isobutyl ketone (MIBK), methyl ethyl ketone, cyclopentanone, cyclohexanone, etc.; ether solvents such as cyclopentyl methyl ether, etc. In addition, as the hydrocarbon solvent, an isoparaffin solvent containing one or more isoparaffins can be used.

[0181] Moreover, as a solvent, for example, "KYOWASOL C900" (manufactured by KH Neochem Co., Ltd.) can also be used.

[0182] Among them, toluene, xylene, methyl isobutyl ketone, chloroform, trichloroethane, and ethyl acetate are preferred because they have excellent solubility in the conductive polymer.

[0183] In the case of the polyaniline composite, the composite can be dissolved even in alcohols such as isopropyl alcohol, 1-butanol, 2-butanol, 2-pentanol, benzyl alcohol, and alkoxy alcohols. Alcohols are preferred over aromatics such as toluene in terms of reducing environmental load.

[0184] When an organic solvent is used as the solvent, a mixed organic solvent of a water-immiscible organic solvent and a water-soluble organic solvent at a ratio of 99 to 1:1 to 99 (mass ratio) is preferably used because generation of gel during storage can be prevented and long-term storage can be achieved.

[0185] The mixed organic solvent may contain one or two or more water-immiscible organic solvents, or may contain one or two or more water-soluble organic solvents.

[0186] The concentration of component (a) relative to the total amount of the solvent (component (b)) [component (a) / (component (a)+component (b))×100 (%)] may be 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, or 2.0% by mass or more. In addition, it is usually 15.0% by mass or less, 13.0% by mass or less, 12.0% by mass or less, 10.0% by mass or less, 9.0% by mass or less, or 8.0% by mass or less.

[0187] When the conductive polymer composition further contains one or more of the components (c) to (e) described below, the concentration of the component (a) is usually 0.3 to 20 mass %, preferably 0.5 to 20 mass %, more preferably 1 to 15 mass %, further preferably 1 to 10 mass %, and further preferably 1 to 7 mass % based on the total amount of the conductive polymer composition.

[0188] The content of the component (b) can be appropriately adjusted according to the amounts of other components and is not limited. For example, it can be 200 to 20,000 parts by mass, 300 to 17,000 parts by mass, 500 to 12,000 parts by mass, 500 to 5,000 parts by mass, or 500 to 1,500 parts by mass, based on 100 parts by mass of the component (a).

[0189] (c) Acid or salt

[0190] In one embodiment of the present aspect, the conductive polymer composition may further contain an acid or a salt (component (c)), or may not contain the acid or the salt.

[0191] Alternatively, component (c) and component (b) may be mixed and used in the form of a mixed solvent. In this case, the concentration of component (a) in the solvent is calculated relative to the total mass of component (b) and component (c).

[0192] There are no particular restrictions on the acid or salt. However, component (c) does not include components (d) and (e) described below. Acid refers to a compound having an acidic group (H ＋) Arrhenius acid or Bronsted acid. For example, sulfonic acid and its salts, phosphoric acid and its salts, phosphoric acid esters and its salts, carboxylic acids and its salts, amino acids and its salts, boric acid and its salts, monosubstituted boric acid (boronic acid) and its salts, etc. can be mentioned.

[0193] As the salt, an ammonium salt or an alkali metal salt (for example, a sodium salt, a lithium salt, a potassium salt, etc.) of the corresponding acid can be used.

[0194] Specifically, phosphoric acid and its salts; monomethyl phosphate, dimethyl phosphate, a mixture of monomethyl phosphate and dimethyl phosphate, and their salts; monoethyl phosphate, diethyl phosphate, a mixture of monoethyl phosphate and diethyl phosphate, and their salts; monoisopropyl phosphate, diisopropyl phosphate, a mixture of monoisopropyl phosphate and diisopropyl phosphate, and their salts; monobutyl phosphate, dibutyl phosphate, a mixture of monobutyl phosphate and dibutyl phosphate, and their salts; mono(2-ethylhexyl) phosphate, di(2-ethylhexyl) phosphate, a mixture of mono(2-ethylhexyl) phosphate and di(2-ethylhexyl) phosphate, and their salts; salts; acetic acid and its salts; propionic acid and its salts; butyric acid and its salts; DL-2-methylbutyric acid and its salts; 2-ethylhexanoic acid and its salts; 3,5,5-trimethylhexanoic acid and its salts; myristic acid and its salts; 2-methylpentanoic acid and its salts; adipic acid and its salts; glycine and its salts; β-alanine and its salts; DL-alanine and its salts; DL-valine and its salts; (±)-10-camphorsulfonic acid and its salts; dioctyl sulfosuccinate and its salts; 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid and its salts; boric acid and borate; dodecylbenzenesulfonic acid and dodecylbenzenesulfonic acid salts; phenylboric acid and phenylborate, etc.

[0195] These may be used alone or in combination of two or more.

[0196] Among the above, phosphate esters and salts thereof, carboxylic acids and salts thereof, carboxylic acid esters and salts thereof, amino acids and salts thereof, etc. It should be noted that a configuration may be adopted in which an acid different from the heat-resistant stabilizer is used.

[0197] The preferred solubility parameter (SP value) of component (c) is 13.0 (cal / cm 3 ) 1 / 2 Below, more preferably 11.0 (cal / cm 3 ) 1 / 2 In addition, it can be set to 10.0 (cal / cm 3 ) 1 / 2 Below. SP value is usually 0 (cal / cm 3 ) 1 / 2 above.

[0198] The SP value is calculated by the Fedors method described in "Polymer Engineering & Science", 1974, Vol. 14, pp. 147-154.

[0199] The component (c) is preferably an acid having a hydrophobic group.

[0200] Examples of the hydrophobic group include a linear alkyl group, a branched alkyl group, an alkylphenyl group, an alkylnaphthyl group, etc. The alkyl group of the linear alkyl group, the branched alkyl group, and the alkyl group contained in the alkylphenyl group and the alkylnaphthyl group preferably have 2 to 20 carbon atoms.

[0201] As component (c), alkyl carboxylic acid, phosphoric acid monoester, phosphoric acid diester, alkylbenzene carboxylic acid, alkylbenzene phosphonic acid, etc. are mentioned. It should be noted that alkylbenzene carboxylic acid is a compound represented by R-Ph-COOH, and alkylbenzene phosphonic acid is R-Ph-PO(OH) 2 The compound shown (wherein R represents an alkyl group and Ph represents a phenyl group).

[0202] The carbon number of the alkyl group of the alkyl carboxylic acid, alkylbenzene carboxylic acid and alkylbenzene phosphonic acid is preferably 2 to 20. The phosphoric acid monoester and phosphoric acid diester are preferably esters obtained from phosphoric acid and an alcohol having 2 to 20 carbon atoms.

[0203] Specific examples of the component (c) include propionic acid, DL-2-methylbutyric acid, 2-methylvaleric acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, myristic acid, monomethyl phosphate, dimethyl phosphate, a mixture of monomethyl phosphate and dimethyl phosphate, monoethyl phosphate, diethyl phosphate, a mixture of monoethyl phosphate and diethyl phosphate, monoisopropyl phosphate, diisopropyl phosphate, a mixture of monoisopropyl phosphate and diisopropyl phosphate, monobutyl phosphate, dibutyl phosphate, a mixture of monobutyl phosphate and dibutyl phosphate, mono(2-ethylhexyl) phosphate, di(2-ethylhexyl) phosphate, and a mixture of mono(2-ethylhexyl) phosphate and di(2-ethylhexyl) phosphate.

[0204] The content of the component (c) in the conductive polymer composition is preferably 0.1 to 70 mass %, more preferably 0.5 to 70 mass %, further preferably 1 to 30 mass %, and further preferably 2 to 20 mass %.

[0205] The content of component (c) can be, for example, 20 to 200 parts by mass, or 25 to 150 parts by mass relative to 100 parts by mass of component (a). It can be 200 to 900 parts by mass, or 400 to 800 parts by mass relative to 100 parts by mass of component (a). In addition, it can be more than 1000 parts by mass, for example, 1100 to 7000 parts by mass, or 1200 to 3000 parts by mass relative to 100 parts by mass of component (a).

[0206] In one embodiment, the conductive polymer composition may further include either or both of (d) a heat stabilizer and (e) a phenolic compound.

[0207] (d) Heat stabilizer

[0208] The heat-resistant stabilizer (component (d)) includes an acidic substance or a salt of an acidic substance. Component (d) does not include components (c) and (e). The acidic substance may be any of an organic acid (acid of an organic compound) or an inorganic acid (acid of an inorganic compound) containing one or more sulfonic acid groups.

[0209] The acidic substance may be any of an organic acid which is an acid of an organic compound and an inorganic acid which is an acid of an inorganic compound, but is preferably an organic acid.

[0210] The acidic substance is preferably an organic acid containing one or more sulfonic acid groups.

[0211] The organic acid having a sulfonic acid group is preferably a cyclic, chain or branched alkylsulfonic acid, a substituted or unsubstituted aromatic sulfonic acid, or a polysulfonic acid having one or more sulfonic acid groups.

[0212] Examples of the alkylsulfonic acid include methanesulfonic acid, ethanesulfonic acid, and di(2-ethylhexyl)sulfosuccinic acid. The alkyl group is preferably a linear or branched alkyl group having 1 to 18 carbon atoms.

[0213] Examples of the aromatic sulfonic acid include aromatic sulfonic acids having 6 to 20 carbon atoms, such as sulfonic acids having a benzene ring, sulfonic acids having a naphthalene skeleton, and sulfonic acids having an anthracene skeleton. Examples of the aromatic sulfonic acid include substituted or unsubstituted benzenesulfonic acid, substituted or unsubstituted naphthalenesulfonic acid, and substituted or unsubstituted anthracenesulfonic acid.

[0214] The substituent is, for example, a substituent selected from an alkyl group (eg, an alkyl group having 1 to 20 carbon atoms), an alkoxy group (eg, an alkoxy group having 1 to 20 carbon atoms), a hydroxyl group, a nitro group, a carboxyl group, and an acyl group, and may be substituted with one or more substituents.

[0215] Specifically, examples of the aromatic sulfonic acid include compounds represented by the following formula (4) or (5).

[0216]

Chemical formula 4

[0217]

[0218] (In formula (4), l is 1 or more, m is an integer of 0 or more and 5 or less, and n is an integer of 0 or more and 5 or less. When one of m or n is 0, the other is 1 or more.)

[0219]

Chemical formula 5

[0220]

[0221] (In formula (5), q is 1 or more, p is an integer of 0 or more and 7 or less, and R is each independently an alkyl group having 1 to 20 carbon atoms, a carboxyl group, a hydroxyl group, a nitro group, a cyano group, or an amino group.)

[0222] l is preferably 1 to 3. m is preferably 1 to 3. n is preferably 0 to 3.

[0223] q is preferably 1 to 3. p is preferably 0 to 3. R is preferably an alkyl group having 1 to 20 carbon atoms, a carboxyl group or a hydroxyl group.

[0224] Examples of the aromatic sulfonic acid include 4-sulfophthalic acid, 5-sulfoisophthalic acid, 5-sulfosalicylic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 2-hydroxy-6-naphthalenesulfonic acid, p-phenolsulfonic acid, toluenesulfonic acid, p-xylene-2-sulfonic acid, 4,4'-biphenyldisulfonic acid, dibenzofuran-2-sulfonic acid, flavinic acid, (+)-10-camphorsulfonic acid, monoisopropylnaphthalenesulfonic acid, 1-pyrenesulfonic acid, etc. Among them, 4-sulfophthalic acid, 5-sulfosalicylic acid, 5-sulfoisophthalic acid, 2-naphthalenesulfonic acid, dibenzofuran-2-sulfonic acid, flavinic acid, 2-hydroxy-6-naphthalenesulfonic acid, and 1-pyrenesulfonic acid are preferred from the viewpoint of improving heat resistance.

[0225] Examples of the salt of the acidic substance include the salts of the compounds listed above, and examples of the counter ion of the salt include sodium, lithium, potassium, cesium, ammonium, calcium, barium and the like.

[0226] Component (d) may be a hydrate.

[0227] The content of the component (d) is preferably 0.1 to 1000 parts by mass, more preferably 1 to 100 parts by mass, further preferably 1 to 30 parts by mass, and further preferably 2 to 8 parts by mass, based on 100 parts by mass of the component (a).

[0228] (e) Phenolic compounds

[0229] The phenolic compound (component (e)) is not particularly limited, and is a compound represented by ArOH (wherein Ar is an aryl group or a substituted aryl group). Note that component (e) is a component different from components (b) to (d).

[0230] Specifically, examples include substituted phenols such as phenol, o-cresol, m-cresol or p-cresol, o-ethylphenol, m-ethylphenol or p-ethylphenol, o-propylphenol, m-propylphenol or p-propylphenol, o-butylphenol, m-butylphenol or p-butylphenol, o-chlorophenol, m-chlorophenol or p-chlorophenol, salicylic acid, hydroxybenzoic acid, and hydroxynaphthalene; polyphenolic compounds such as catechol and resorcinol; and polymer compounds such as phenolic resins, polyphenols, and poly(hydroxystyrene).

[0231] In addition, a phenolic compound represented by the following formula (6) can be used.

[0232]

Chemical formula 6

[0233]

[0234] (In formula (6), n is an integer of 1 to 5. When n is 2 or more, a plurality of R 21 They may be the same or different.

[0235] R 21 alkyl having 2 to 10 carbon atoms, alkenyl having 2 to 20 carbon atoms, alkylthio having 1 to 20 carbon atoms, cycloalkyl having 3 to 10 carbon atoms, aryl having 6 to 20 carbon atoms, alkylaryl having 7 to 20 carbon atoms or arylalkyl having 7 to 20 carbon atoms.

[0236] As the above R 21 Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and tert-pentyl.

[0237] Examples of the alkenyl group include substituents having an unsaturated bond in the molecule of the above-mentioned alkyl group.

[0238] Examples of the cycloalkyl group include cyclopentane and cyclohexane.

[0239] Examples of the alkylthio group include a methylthio group and an ethylthio group.

[0240] Examples of the aryl group include a phenyl group and a naphthyl group.

[0241] Examples of the alkylaryl group and the arylalkyl group include substituents obtained by combining the above-mentioned alkyl group and aryl group.

[0242] Among these groups, R 21 , preferably methyl or ethyl.

[0243] The content of the component (e) is preferably 10 to 5000 parts by mass, more preferably 10 to 2000 parts by mass, and even more preferably 10 to 1000 parts by mass, based on 100 parts by mass of the component (a).

[0244] The content of the component (e) may be 100 to 10,000 parts by mass based on 100 parts by mass of the component (a).

[0245] The use of the phenolic compound is preferred because the conductivity is improved or the solubility in alcohol is improved.

[0246] The content of component (e) in the conductive polymer composition is 1 to 80 mass %, more preferably 5 to 60 mass %, and even more preferably 10 to 40 mass %. The use of the phenolic compound is preferred because the conductivity is improved or the solubility in alcohol is improved.

[0247] Alternatively, component (e) and component (b) may be mixed and used in the form of a mixed solvent. In this case, the concentration of component (a) in the solvent is calculated relative to the total mass of component (b) and component (e).

[0248] The conductive polymer composition may be basically composed of components (a) and (b), and optionally one or more components selected from (c), (d) and (e). In this case, unavoidable impurities may be contained. For example, 70% by mass or more, 80% by mass or more, 90% by mass or more, 98% by mass or more, 99% by mass or more, or 99.5% by mass or more of the conductive polymer composition may be components (a) and (b), and optionally one or more components selected from (c), (d) and (e). In addition, the conductive polymer composition may be composed only of components (a) and (b), and optionally one or more components selected from (c), (d) and (e).

[0249] In the conductive polymer-containing porous body obtained by the production method of this embodiment, a layer containing the conductive polymer is formed inside the pores of the porous body having surface irregularities and on the surface of the porous body.

[0250] [Porous body containing conductive polymer]

[0251] The conductive polymer-containing porous body of the present embodiment is obtained by the above-mentioned method for producing a conductive polymer-containing porous body of the present embodiment. The porous body and the conductive polymer are as described above.

[0252] It should be noted that the conductive polymer-containing porous body having the solid electrolyte layer formed thereon may be immersed in a solution containing the above-mentioned component (d). In this case, the component (d) is preferably a sulfonate represented by the above-mentioned formula (4) or a salt thereof.

[0253] The solution containing the impregnated component (d) may contain a solvent.

[0254] The solvent is not particularly limited as long as it can dissolve component (d), and examples thereof include water, alcohol solvents, ketone solvents, ether solvents, ester solvents, etc. The solvent may be used alone or in combination of two or more.

[0255] Specific examples of the solvent include methanol, ethanol, isopropanol, n-butanol, 1-methoxy-2-propanol, 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol, 1-ethoxy-2-propanol, ethyl acetate, butyl acetate, MIBK, methyl ethyl ketone (MEK), ethylene glycol mono-tert-butyl ether, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether.

[0256] The content of component (d) in the immersion solution is preferably 0.1% by mass to 10% by mass, more preferably 0.3% by mass to 6% by mass, and even more preferably 0.7% by mass to 3.5% by mass.

[0257] Examples of the impregnation method include dipping.

[0258] The immersion time is preferably 1 minute or longer, more preferably 3 minutes or longer and 200 minutes or shorter. The immersion temperature is preferably 5°C to 50°C.

[0259] Drying after immersion is preferably performed using an oven, a hot plate, or the like.

[0260] The drying temperature is preferably 80 to 200°C, more preferably 100 to 170°C.

[0261] The drying time is preferably 1 to 180 minutes, more preferably 3 to 60 minutes. If necessary, heating may be performed under reduced pressure. The drying temperature and drying time are not particularly limited and may be appropriately selected according to the material used.

[0262] As described above, component (d) may be added to the conductive polymer composition, or the porous body impregnated with the conductive polymer composition may be immersed in a solution of component (d). Alternatively, component (d) may be added to the composition, and the porous body may be immersed in a solution of component (d).

[0263] That is, in the porous body containing a conductive polymer obtained by the manufacturing method of one embodiment of the present invention, there is a component (d) added to the conductive polymer composition (hereinafter, sometimes referred to as component (d1)) and a component (d) impregnated after being impregnated in the conductive polymer composition (hereinafter, sometimes referred to as component (d2)). Components (d1) and (d2) may be the same or different. In different cases, for example, component (d1) is a compound represented by the above formula (5), and component (d2) is a compound represented by the above formula (4).

[0264] [Porous body with solid electrolyte layer]

[0265] The layer containing the conductive polymer formed inside the pores of the porous body and on the surface of the porous body by the method for producing a porous body containing a conductive polymer functions as a solid electrolyte layer.

[0266] The porous body with a solid electrolyte layer of the present embodiment is a porous body having an oxide of a valve metal, and has a solid electrolyte layer containing polyaniline formed inside pores of the porous body and a solid electrolyte layer containing polyaniline coated on the outside of the porous body.

[0267] The porous body with a solid electrolyte layer of this embodiment has a solid electrolyte layer formed both inside the pores of the porous body and outside the porous body.

[0268] In the porous body with a solid electrolyte layer of the present method, since the solid electrolyte layer penetrates deeply into the pores of the porous body, the coating area of ​​the solid electrolyte layer on the pore surface of the porous body increases. Therefore, the dielectric loss tangent of the solid electrolyte capacitor using it becomes smaller. In addition, the equivalent series resistance (ESR) of the solid electrolyte layer capacitor using the porous body with a solid electrolyte layer of the present method becomes smaller, and the capacitance becomes higher.

[0269] The solid electrolytic capacitor including the porous body with a solid electrolyte layer of this embodiment has an equivalent series resistance ESR of 17 mΩ or less.

[0270] [Method for manufacturing solid electrolytic capacitor]

[0271] The method for manufacturing the solid electrolytic capacitor of this embodiment includes the following steps.

[0272] An impregnation step (A): an impregnation step of immersing a part or the whole of an anode body, which is a porous body containing a valve metal and having a surface containing an oxide of a valve metal, in a conductive polymer composition containing a conductive polymer and a solvent;

[0273] Holding step (B): a step of taking the anode body out of the conductive polymer composition used in the previous impregnation step and holding it for a predetermined holding time at a temperature below the boiling point of the solvent contained in the conductive polymer composition used in the previous impregnation step;

[0274] An immersion step (C): an immersion step of immersing a part or the whole of the anode body after the holding step (B) in a conductive polymer composition containing a conductive polymer and a solvent which is the same as or different from the conductive polymer composition used in the previous immersion step;

[0275] Drying step (D): a step of taking out the anode body from the conductive polymer composition and drying it at a temperature exceeding the boiling point of the solvent to form a solid electrolyte layer containing a conductive polymer on the anode body.

[0276] A conventional method for manufacturing a solid electrolytic capacitor includes a step of roughening the surface of an anode metal (valve metal), a step of forming a dielectric film (a film of a valve metal oxide) on the roughened surface of the anode metal, and a step of forming a solid electrolyte layer. In addition, a step of forming a cathode in a manner opposed to the anode via the solid electrolyte layer is also included.

[0277] All the above steps may be performed, or the step of immersing an existing product having corresponding anodes and cathodes formed thereon (the anode body has been roughened and dried) in the conductive polymer composition may be performed.

[0278] The porous body containing a conductive polymer used in the solid electrolyte capacitor obtained by the manufacturing method of this mode has an anode body and a solid electrolyte layer. The anode body is a porous body having pores (porous) on the surface. The anode body contains a valve metal, and its surface contains an oxide of the valve metal. In this way, a solid electrolyte layer is formed on the anode body having an uneven surface. In the present invention, since the solid electrolyte layer enters the pores of the anode body more deeply, the coating area of ​​the solid electrolyte layer on the pore surface of the anode body (porous body) increases, and the dielectric loss tangent of the capacitor containing the solid electrolyte layer decreases. In addition, in the present invention, the coating area of ​​the pore surface of the anode body (porous body) is increased by the solid electrolyte layer, so that the equivalent series resistance (ESR) of the capacitor containing the solid electrolyte layer is reduced, and the capacity is increased.

[0279] Hereinafter, the manufacturing method will be described.

[0280] (Process of roughening the surface of the anode metal)

[0281] In this process, the surface of the anode metal (valve metal) of the solid electrolytic capacitor is roughened (etched) to increase the effective surface area. Alternatively, a porous body with an increased effective surface area is obtained by sintering fine powder of the anode metal (valve metal).

[0282] Examples of the anode metal include valve metals such as aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony, and aluminum or tantalum is preferred.

[0283] Roughening (etching) can be performed by a known method, for example, a method of immersing in a hydrochloric acid solution (chemical etching), a method of electrolyzing aluminum as an anode in a hydrochloric acid aqueous solution (electrochemical etching), or the like.

[0284] (Process of forming a dielectric film on the surface of the anode metal)

[0285] In this process, a dielectric oxide film is formed on the roughened anode surface. This process is usually performed by applying a voltage in an electrolyte to perform anodization (chemical conversion). Thus, a film containing an oxide (dielectric) of the anode metal is formed, and an anode body containing a valve metal and its oxide can be obtained.

[0286] Examples of the electrolyte used include aqueous solutions containing adipic acid, citric acid, phosphoric acid, and salts thereof. Anodization can be performed by a known method.

[0287] (Capacitor element formation process)

[0288] Generally, after the above-mentioned anodic oxidation, a capacitor element is formed using an anode electrode (an anode body including a valve metal and an oxide thereof) and a cathode electrode. The element shape is not particularly limited, and may be, for example, a wound element or a stacked element.

[0289] In the case of a winding type, an anode electrode and a cathode electrode are wound with a separator interposed therebetween to form a capacitor element. In the case of a stacked type, a plurality of anode electrodes and a plurality of cathode electrodes are stacked on each other to form a capacitor element.

[0290] The capacitor element in this step can be formed by a known method.

[0291] (Step of immersing the anode body in a conductive polymer solution and drying it)

[0292] In this process, an anode body comprising a valve metal and an oxide thereof is immersed in a conductive polymer composition (process (A)), the anode body is removed from the conductive polymer composition used in the impregnation process (A), and maintained at a temperature below the boiling point of the solvent contained in the conductive polymer composition used in the impregnation process (A) (process (B)). Thereafter, the anode body is immersed in a conductive polymer composition comprising a conductive polymer and a solvent which is the same as or different from the conductive polymer composition used in the impregnation process (A) (process (C)), and dried, thereby forming a solid electrolyte layer comprising a conductive polymer inside the pores and on the surface of the anode body.

[0293] In one embodiment, the cycle of step (B) and step (C) may be repeated multiple times.

[0294] When the cycle of steps (B) and (C) is repeated multiple times, the conductive polymer composition used to impregnate the anode body in each step (C) may be the same as the conductive polymer composition used in the steps (A) and (C) that have already been performed, or may be different from the conductive polymer composition used in the steps (A) and (C) that have already been performed.

[0295] The method of impregnation in the conductive polymer composition is not particularly limited as long as the conductive polymer can be sufficiently impregnated into the pores of the anode body, but a method of immersing the capacitor element itself in the conductive polymer composition is preferred.

[0296] The other aspects of step (A) to step (C) can be carried out in the same manner as the steps (A) to (C) for producing the above-mentioned porous body containing the conductive polymer. Thus, the solid electrolyte layer containing the conductive polymer can be formed deep into the pores of the anode body, so that the coating area of ​​the conductive polymer on the pore surface of the porous body is increased, and the dielectric loss tangent of the capacitor is reduced.

[0297] Furthermore, by performing the above steps (A) to (C), the coating area of ​​the pore surface of the porous body by the conductive polymer increases, so that the equivalent series resistance (ESR) of the capacitor decreases and the electrostatic capacitance increases.

[0298] Furthermore, since sufficient capacitor characteristics can be obtained even with a smaller number of immersion times than conventional ones, the number of immersion times in the conductive polymer composition can be reduced (step (C)).

[0299] In addition, the conductive polymer composition is the same as the conductive polymer composition described above.

[0300] The drying temperature is a temperature higher than the boiling point of the solvent contained in the conductive polymer composition and may be appropriately selected depending on the type of the solvent, and is usually 30 to 200° C., preferably 100 to 180° C. The drying time is usually 10 to 120 minutes, preferably 30 to 90 minutes.

[0301] (External coating)

[0302] An external coating layer may be further formed on the anode body having the solid electrolyte layer formed thereon. By coating the anode body externally, the contact with the cathode becomes good, thereby reducing the equivalent series resistance (ESR) of the capacitor element. In addition, by coating the capacitor element externally, the capacitor element can be protected from external impact and the influence of external air.

[0303] The outer coating layer can be formed, for example, by immersing the anode body having the solid electrolyte layer formed thereon in a composition for forming the outer coating layer and then drying the composition.

[0304] The composition for forming the outer coating layer is not particularly limited as long as it contains a conductive polymer and a solvent or a dispersion medium. As the composition for forming the outer coating layer, for example, the same conductive polymer composition as described in the method for producing a porous body containing a conductive polymer can be suitably used.

[0305] The method for immersing the anode body in the composition for forming the outer coating layer is not particularly limited. The immersion time is usually 1 to 30 minutes, preferably 1 to 10 minutes.

[0306] The drying temperature is usually 30 to 200° C., preferably 100 to 180° C. The drying time is usually 10 to 120 minutes, preferably 30 to 90 minutes.

[0307] [Solid electrolytic capacitors]

[0308] The solid electrolytic capacitor of this embodiment can be obtained by the above-mentioned method for manufacturing the solid electrolytic capacitor of this embodiment. Specifically, it includes an anode material (an anode body including a valve metal and an oxide thereof) containing a solid electrolyte (solid electrolyte layer), and the solid electrolyte (solid electrolyte layer) includes the conductive polymer.

[0309] In one embodiment, the dielectric loss tangent of the solid electrolytic capacitor may be appropriately selected according to the type and shape of the capacitor to be manufactured, and may be, for example, 0.5 or less, 0.35 or less, 0.20 or less, or 0.10 or less.

[0310] In addition, the dielectric loss tangent is measured by the method described in the examples.

[0311] In one embodiment of the solid electrolytic capacitor of the present aspect, the equivalent series resistance ESR is 17 mΩ or less.

[0312] The solid electrolytic capacitor of this type can be used as a circuit element mounted on an electric or electronic circuit board, particularly a circuit element mounted in an automobile or the like.

[0313] Example

[0314] Production Example 1 (Production of Polyaniline Composite 1)

[0315] 32.4 g of "NEOCOL SWC" (sodium di-2-ethylhexyl sulfosuccinate, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 13.3 g of aniline, and 0.9 g of "SORBON T-20" (a nonionic emulsifier having a polyoxyethylene sorbitan fatty acid ester structure, manufactured by Toho Chemical Industry Co., Ltd.) were added to a 1000 mL separable flask and dissolved in 320.4 g of toluene. 450 g of an 8.5 mass % phosphoric acid aqueous solution was added thereto, and the reaction liquid having two liquid phases of toluene and water was stirred, and the internal temperature of the reaction liquid was cooled to 5°C. When the internal temperature of the reaction liquid reached 5°C, a solution prepared by dissolving 39.3 g of APS (ammonium persulfate) in 90.2 g of an 8.5 mass % phosphoric acid aqueous solution was added using a dropping funnel while stirring the reaction liquid, and the solution was stirred for 4 hours while the internal temperature of the solution was kept at 5°C. After the stirring was stopped, the contents were transferred to a separatory funnel, and the aqueous phase and the toluene phase (organic phase) were allowed to stand for separation. After separation, the toluene phase (organic phase) was washed once with 180.3 g of an 8.5 mass % phosphoric acid aqueous solution and five times with 328.0 g of ion exchange water, thereby obtaining a polyaniline complex toluene solution. The solution was transferred to an evaporator, heated in a hot water bath at 60° C., and reduced pressure, thereby evaporating and distilling off the volatile components to obtain a polyaniline complex 1 (protonated polyaniline).

[0316] The weight average molecular weight (Mw) of the polyaniline of the polyaniline composite 1 was 73,000.

[0317] The weight average molecular weight of polyaniline in the polyaniline composite 1 and the polyaniline composite 2 described later was measured as follows.

[0318] 1.65-1.85 g of lithium bromide was dissolved in 2000 mL of NMP (N-methyl-2-pyrrolidone) to prepare a 0.01 M lithium bromide NMP solution. 14 μL of triethylamine was added to 10 mL of the 0.01 M lithium bromide NMP solution, and the mixture was stirred to dissolve to prepare a uniform solution. In addition, 50 μL of the polyaniline complex toluene solution was added dropwise, stirred and mixed, and then filtered through a 0.45 μm filter to prepare a sample for gel permeation chromatography (GPC) measurement.

[0319] The GPC measurement was performed using a GPC column (“Shodex KF-806M” manufactured by Showa Denko K.K., two connected columns) under the following measurement conditions.

[0320] Solvent: NMP containing 0.01M LiBr

[0321] Flow rate: 0.70mL / min

[0322] Column temperature: 60°C

[0323] Injection volume: 100 μL

[0324] UV detection wavelength: 270nm

[0325] The weight average molecular weight obtained by the above method is a polystyrene (PS) conversion value.

[0326] The doping ratio of proton donor (sodium di-2-ethylhexylsulfosuccinate) to polyaniline is 0.36.

[0327] Production Example 2 (Production of Polyaniline Composite 2)

[0328] 10.13 g of "NEOCOL SWC" (sodium di-2-ethylhexyl sulfosuccinate, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 4.17 g of aniline, and 0.32 g of "SORBON T-20" (a nonionic emulsifier having a polyoxyethylene sorbitan fatty acid ester structure, manufactured by Toho Chemical Industry Co., Ltd.) were added to a 1000 mL separable flask and dissolved in 238.37 g of toluene. 353.70 g of a 17 mass % phosphoric acid aqueous solution was added thereto, and the reaction liquid having two liquid phases of toluene and water was stirred, and the internal temperature of the reaction liquid was cooled to -2°C. When the internal temperature of the reaction liquid reached -2°C, a solution prepared by dissolving 12.3 g of APS (ammonium persulfate) in 48 g of a 17 mass % phosphoric acid aqueous solution was added using a dropping funnel while stirring the reaction liquid, and the solution was stirred for 18 hours while the internal temperature of the solution was kept at -2°C.

[0329] After the stirring stopped, the contents were transferred to a separatory funnel, and the aqueous phase and the toluene phase (organic phase) were allowed to stand for separation. After separation, the toluene phase (organic phase) was washed once with 59.4 g of an 8.5 mass % phosphoric acid aqueous solution and three times with 108.14 g of ion exchange water, thereby obtaining a polyaniline complex toluene solution. The solution was transferred to an evaporator, heated in a hot water bath at 60°C, and decompressed to evaporate and distill off the volatile components, thereby obtaining a polyaniline complex 2 (protonated polyaniline). The weight average molecular weight (Mw) of the polyaniline of the polyaniline complex 2 was 112,000.

[0330] The doping ratio of proton donor (sodium di-2-ethylhexylsulfosuccinate) to polyaniline is 0.36.

[0331] Manufacturing Example 3 (Manufacturing of anode body)

[0332] A voltage of 8.8 V was applied to 20 tantalum powder sintered bodies (porous bodies of 1.31 mm×2.55 mm×2.30 mm) in a 0.5% phosphoric acid electrolyte in the form of pellets made of tantalum powder having a specific capacity of 250,000 μFV / g for anodization, thereby forming a dielectric (tantalum oxide) on the surface of the tantalum powder sintered bodies (porous bodies) to obtain anode bodies of tantalum capacitors.

[0333] The liquid capacity of the anode body was measured using 10 wt % phosphoric acid as the electrolyte and a platinum black electrode as the counter electrode. The liquid capacity of the anode body was 1341 μF.

[0334] Example 1

[0335] (1) Preparation of conductive polymer composition for forming solid electrolyte layer

[0336] 15 g of isopropyl alcohol (component (b); boiling point 82.5° C.) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 32 g of p-tert-amylphenol (component (e)) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 53 g of 4-methyltetrahydropyran (component (b); boiling point 105° C.) (manufactured by Tokyo Chemical Industry Co., Ltd.) were stirred and mixed until uniform, to prepare a mixed solvent A.

[0337] In 95 g of the mixed solvent A, 5 g of the polyaniline composite 1 (component (a)) obtained in Production Example 1 was dissolved to obtain a polyaniline composite solution A (polyaniline composite concentration: 5 mass %).

[0338] Heat-resistant stabilizer solution A was prepared by dissolving 10 g of 2-naphthalenesulfonic acid hydrate (component (d)) (manufactured by Tokyo Chemical Industry Co., Ltd.) in 90 g of isopropyl alcohol (component (b); boiling point 82.5° C.) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0339] 0.11 g of the heat-resistant stabilizer solution A was added to 10 g of the polyaniline composite solution A (polyaniline composite concentration: 5 mass %), and the mixture was stirred and mixed, thereby obtaining a conductive polymer composition A.

[0340] (2) Formation of solid electrolyte layer

[0341] [Immersion 1st time]

[0342] The anode body obtained in Manufacturing Example 3 was fixed to a metal rod and suspended in such a manner that the length in the height direction became 2.3 mm, and was immersed in the conductive polymer composition A from the lower end side of the anode body to 1 / 3 of the height, and kept for 3 minutes. Next, the conductive polymer composition A was immersed from the lower end side of the anode body to 2 / 3 of the height, and kept for 2 minutes. Next, the entire anode body was immersed in the conductive polymer composition A, and kept for 1 minute.

[0343] Through the above operation, the first impregnation of the anode body was performed.

[0344] Next, the anode body was pulled out from the conductive polymer composition A, and the anode body was kept at room temperature for 1 minute in a state where the entire anode body was exposed to air.

[0345] [Second dipping]

[0346] Next, the anode body was immersed in the conductive polymer composition A from the lower end side to 1 / 3 of the height for 3 minutes. Next, the anode body was immersed in the conductive polymer composition A from the lower end side to 2 / 3 of the height for 2 minutes. Next, the entire anode body was immersed in the conductive polymer composition A for 1 minute.

[0347] Through the above operation, the second impregnation of the anode body was performed.

[0348] Next, the anode body was pulled out from the conductive polymer composition A, and dried at 40° C. for 7 minutes, and then further dried at 140° C. for 30 minutes to form a solid electrolyte layer.

[0349] (3) Preparation of conductive polymer composition for external coating

[0350] 30 g of 3-methoxy-3-methylbutanol (component (b)) (manufactured by Tokyo Chemical Industry Co., Ltd.), 10 g of ethylene glycol (component (b)) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 40 g of p-tert-amylphenol (component (e)) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 20 g of "KYOWASOL C900" (component (b)) (manufactured by KH Neochem Co., Ltd.) were stirred and mixed until uniform, thereby preparing a mixed solvent B.

[0351] 10 g of the polyaniline composite 2 (component (a)) obtained in Production Example 2 was dissolved in 95 g of the mixed solvent B to obtain a polyaniline composite solution B (polyaniline composite 2 concentration: 10 mass %).

[0352] Heat-resistant stabilizer solution B was prepared by dissolving 10 g of 2-naphthalenesulfonic acid hydrate (component (d)) (manufactured by Tokyo Chemical Industry Co., Ltd.) in 90 g of 3-methoxy-3-methylbutanol (component (b); boiling point 174° C.) (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0353] 0.22 g of the heat-resistant stabilizer solution B was added to 10 g of the polyaniline composite solution B (polyaniline composite 2 concentration: 10 mass %), and the mixture was stirred and mixed to obtain a conductive polymer composition B for external coating.

[0354] (4) Formation of external coating layer

[0355] First, the entire anode body having the solid electrolyte layer formed thereon was immersed in a 4-sulfophthalic acid solution (4-sulfophthalic acid concentration: 1 mass %) in which 4-sulfophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in isopropyl alcohol for 10 minutes.

[0356] Next, the anode body was lifted out of the 4-sulfophthalic acid solution and taken out, and dried at 150° C. for 60 minutes.

[0357] Next, the entire anode body having the solid electrolyte layer formed thereon was immersed in the conductive polymer composition B for external coating and kept there for 5 minutes.

[0358] Next, the anode body was pulled out from the conductive polymer composition B, dried at 80° C. for 60 minutes, and then further dried at 170° C. for 30 minutes to coat the outside of the anode body on which the solid electrolyte layer was formed.

[0359] Next, the entire anode body was immersed in a 4-sulfophthalic acid solution (4-sulfophthalic acid concentration: 1 mass %) in which 4-sulfophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in isopropyl alcohol for 10 minutes.

[0360] Next, the anode body was pulled out from the 4-sulfophthalic acid solution and taken out, and dried at 150° C. for 60 minutes to obtain an anode body with a solid electrolyte layer.

[0361] <Evaluation of electrical properties>

[0362] The anode body with a solid electrolyte layer produced in Example 1 was immersed in a carbon paste solution prepared by diluting 0.2 g of carbon paste "TU-10S" (produced by Asahi Chemical Research Laboratory Co., Ltd.) with 7.8 g of diethylene glycol monoethyl ether (produced by Tokyo Chemical Industry Co., Ltd.) and stirring and mixing for 10 seconds, and then dried at 150° C. for 30 minutes.

[0363] Next, 0.8 g of silver paste "4922N" (manufactured by DuPont) was diluted with 0.4 g of n-butyl acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and stirred and mixed, and the above-mentioned anode body was immersed in the obtained silver paste solution for 10 seconds, dried at 40°C for 30 minutes, and further dried at 105°C for 60 minutes to obtain a capacitor.

[0364] The capacitors obtained above were measured for capacitance (Cap) and dielectric loss (tan δ) at a frequency of 120 Hz and equivalent series resistance (ESR) at a frequency of 100 kHz using an LCR meter “Precision LCR Meter E4980A” (manufactured by Agilent Technologies Japan, Ltd.). The evaluation results are shown in Table 1.

[0365] It should be noted that the "capacitance development rate" in Table 1 is a value obtained by dividing the measured value of the electrostatic capacitance (Cap) of each capacitor element having a solid electrolyte layer formed using a conductive polymer by the liquid capacity. The higher the capacity development rate, the better the capacitor characteristics. The capacity development rate is calculated by the following formula (α).

[0366] Capacity development rate [%] = electrostatic capacitance of solid electrolytic capacitor (Cap) / liquid capacity × 100 ... (α)

[0367] Example 2

[0368] In the step “(2) Formation of solid electrolyte layer” of Example 1, after the anode body was immersed in the conductive polymer composition A for the second time, the anode body was pulled out of the conductive polymer composition A and kept at room temperature for 1 minute while the entire anode body was exposed to air.

[0369] Next, the anode body was immersed in the conductive polymer composition A from the lower end side to 1 / 3 of the height for 3 minutes. Next, the anode body was immersed in the conductive polymer composition A from the lower end side to 2 / 3 of the height for 2 minutes. Next, the entire anode body was immersed in the conductive polymer composition A for 1 minute.

[0370] Next, the anode body was pulled out from the conductive polymer composition A, and dried at 40° C. for 7 minutes, and then further dried at 140° C. for 30 minutes to form a solid electrolyte layer.

[0371] The other steps were carried out in the same manner as in Example 1 to obtain an anode body with a solid electrolyte layer.

[0372] Using the obtained anode body, a capacitor was produced in the same manner as in Example 1, and the electrical characteristics were evaluated. The evaluation results are shown in Table 1.

[0373] Comparative Example 1

[0374] In the step “(2) Formation of solid electrolyte layer”, after the anode body is immersed in the conductive polymer composition A for the first time, the anode body is lifted out of the conductive polymer composition A and taken out, dried at 40° C. for 7 minutes, and further dried at 140° C. for 30 minutes to form a solid electrolyte layer.

[0375] The other steps were carried out in the same manner as in Example 1 to obtain an anode body with a solid electrolyte layer.

[0376] Using the obtained anode body, a capacitor was produced in the same manner as in Example 1, and the electrical characteristics were evaluated. The evaluation results are shown in Table 1.

[0377]

Table 1

[0378]

[0379] Manufacturing Example 4 (Manufacturing of anode body)

[0380] A voltage of 8.8 V was applied to 20 tantalum powder sintered bodies (porous bodies measuring 1.71 mm × 3.01 mm × 2.89 mm) in a 0.5% phosphoric acid electrolyte in the form of pellets made of tantalum powder having a specific capacity of 70,000 μFV / g for anodization, thereby forming a dielectric (tantalum oxide) on the surface of the tantalum powder sintered bodies (porous bodies) to obtain anode bodies of tantalum capacitors.

[0381] The liquid capacity of the anode body was measured using 10 wt % phosphoric acid as the electrolyte and a platinum black electrode as the counter electrode. The liquid capacity of the anode body was 961 μF.

[0382] Example 3

[0383] Using the anode body obtained in Manufacturing Example 4, a solid electrolyte layer was formed on the anode body in the same manner as in Example 1 except that the anode body was fixed to a metal rod and suspended so that the length in the height direction was 2.89 mm in “(2) Formation of Solid Electrolyte Layer” and the anode body was impregnated.

[0384] The other steps were carried out in the same manner as in Example 1 to obtain an anode body with a solid electrolyte layer.

[0385] Using the obtained anode body, a capacitor was produced in the same manner as in Example 1, and the electrical characteristics were evaluated. The evaluation results are shown in Table 2.

[0386] Comparative Example 2

[0387] A solid electrolyte layer was formed on the anode body in the same manner as in Comparative Example 1 except that the anode body obtained in Production Example 4 was used.

[0388] The other steps were carried out in the same manner as in Comparative Example 1 to obtain an anode body with a solid electrolyte layer.

[0389] Using the obtained anode body, a capacitor was produced in the same manner as in Example 1, and the electrical characteristics were evaluated. The evaluation results are shown in Table 2.

[0390]

Table 2

[0391]

[0392] As shown in Tables 1 and 2, in Examples 1 to 3, after the first immersion of the anode body, the anode body was exposed to air at a temperature below the boiling point of the solvent (82.5°C), and then the second immersion was performed. Therefore, the dielectric loss tangent in the capacitor was suppressed to a small value, the equivalent series resistance (ESR) was small, and a high capacity realization rate could be obtained.

[0393] This is presumably because the conductive polymer composition smoothly permeates into the pores of the anode body during the second and subsequent immersions, and a conductive polymer film is densely formed on the pore surfaces of the anode body, increasing the film area on the pore surfaces.

[0394] Industrial Applicability

[0395] The solid electrolytic capacitor obtained by the production method of the present invention can be used as a circuit element mounted on an electric or electronic circuit board, particularly a circuit element mounted on an automobile or the like.

[0396] Several embodiments and / or examples of the present invention have been described in detail above, but it is easy for those skilled in the art to make various changes to these illustrative embodiments and / or examples without departing substantially from the new teachings and effects of the present invention. Therefore, these various changes are included within the scope of the present invention.

[0397] The contents of the documents described in this specification and the application serving as the basis for the Paris Convention priority claim of the present application are incorporated herein in their entirety.

Claims

1. A method for producing a porous body containing a conductive polymer, comprising the following steps: Impregnation step A: an impregnation step of immersing a part or the whole of the porous body having an oxide of a valve metal in a conductive polymer composition containing a conductive polymer and a solvent; Holding step B: a step of taking the porous body out of the conductive polymer composition used in the previous impregnation step and holding it at a temperature below the boiling point of the solvent contained in the conductive polymer composition used in the previous impregnation step for a predetermined holding time; Immersing step C: an immersion step of immersing a part or the whole of the porous body after the holding step B in a conductive polymer composition containing a conductive polymer and a solvent which is the same as or different from the conductive polymer composition used in the previous immersion step.

2. The method for producing a porous body containing a conductive polymer according to claim 1, comprising the step of immersing a portion of the porous body in the conductive polymer composition and maintaining the immersion state, and then immersing a non-impregnated portion of the porous body in the conductive polymer composition.

3. The method for producing a porous body containing a conductive polymer according to claim 1 or 2, wherein: In the step B, the holding time is 1 second or longer and less than 10 minutes.

4. The method for producing a porous body containing a conductive polymer according to any one of claims 1 to 3, wherein: The step B and the step C are repeated multiple times.

5. The method for producing a porous body containing a conductive polymer according to any one of claims 1 to 4, wherein: The conductive polymer is one or more selected from the group consisting of polyaniline, polyaniline derivatives, polythiophene, polythiophene derivatives, polypyrrole, and polypyrrole derivatives.

6. The method for producing a porous body containing a conductive polymer according to any one of claims 1 to 5, wherein: The conductive polymer is a polyaniline composite obtained by doping polyaniline with a proton donor.

7. The method for producing a porous body containing a conductive polymer according to any one of claims 1 to 6, wherein: The conductive polymer composition further includes a phenolic compound.

8. The method for producing a porous body containing a conductive polymer according to any one of claims 1 to 7, wherein: The conductive polymer composition further includes a heat stabilizer. 9 . A conductive polymer-containing porous body obtained by the method for producing a conductive polymer-containing porous body according to claim 1 .

10. A method for manufacturing a solid electrolytic capacitor, comprising the following steps: An impregnation step A is an impregnation step of immersing a part or the whole of an anode body, which is a porous body having a surface containing an oxide of a valve metal and containing a valve metal, in a conductive polymer composition containing a conductive polymer and a solvent; Holding step B: a step of taking the anode body out of the conductive polymer composition used in the previous impregnation step and holding it at a temperature below the boiling point of the solvent contained in the conductive polymer composition used in the previous impregnation step for a predetermined holding time; An immersion step C is an immersion step of immersing a part or the whole of the anode body after the holding step B in a conductive polymer composition containing a conductive polymer and a solvent which is the same as or different from the conductive polymer composition used in the previous immersion step; Drying step D: a drying step of taking out the anode body from the conductive polymer composition and drying it at a temperature exceeding the boiling point of the solvent to form a solid electrolyte layer containing a conductive polymer on the anode body. 11 . The method for manufacturing a solid electrolytic capacitor according to claim 10 , further comprising the step of immersing the anode body having the solid electrolyte layer formed thereon in a conductive polymer composition containing a conductive polymer and a solvent, and then drying the composition to form an outer coating layer. 12 . A solid electrolytic capacitor obtained by the method for producing a solid electrolytic capacitor according to claim 10 or 11 .

13. A porous body with a solid electrolyte layer, comprising an oxide of a valve metal, the porous body comprising: a solid electrolyte layer formed inside the pores of the porous body and containing polyaniline; and A solid electrolyte layer is coated on the outside of the porous body and includes polyaniline. 14 . A solid electrolytic capacitor comprising the porous body with a solid electrolyte layer according to claim 13 , wherein an equivalent series resistance (ESR) of the solid electrolytic capacitor is 17 mΩ or less.

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