JP2017015461A - Galvanic cell oxygen sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a galvanic cell oxygen sensor which offers improved durability of a gold sputtering film, provides a stable sensor output, and is less susceptible to leakage of electrolyte.SOLUTION: A galvanic cell oxygen sensor X comprises, in a casing 1, a positive electrode 2 containing a precious metal, a negative electrode 3, an electrolyte 4 in contact with the positive electrode 2 and the negative electrode 3, an electrolyte accommodating section 5 for accommodating the electrolyte 4, and a gas permeable diaphragm 6 that allows a detection target gas to pass therethrough. The positive electrode 2 has peeling prevention means 10 which is provided on an electrolyte accommodating section 5 side thereof to prevent peeling of the positive electrode 2.SELECTED DRAWING: Figure 1

Description

  The present invention provides a casing having a positive electrode containing a noble metal, a negative electrode, an electrolytic solution in contact with the positive electrode and the negative electrode, an electrolytic solution containing part for containing the electrolytic solution, and a gas permeability that allows the gas to be detected to permeate. A galvanic cell type oxygen sensor provided with a diaphragm.

  In general, a galvanic cell type oxygen sensor measures a reaction current generated when oxygen is used as a reactant of a battery composed of two electrodes (a noble metal and a base metal), a gas permeable diaphragm and an electrolyte solution. Oxygen reduction is caused between the positive and negative electrodes due to the presence of oxygen, and the oxygen concentration is measured. Specifically, when oxygen penetrates into the sensor through the oxygen permeable membrane, which is a gas permeable diaphragm, from the outside through the gas vent, oxygen is dissolved in the electrolyte solution, and the oxygen dissolved in the electrolyte solution is It moves onto the positive electrode and is reduced, and the negative electrode is oxidized through the electrolytic solution. Thereby, a current corresponding to the amount of oxygen flows from the positive electrode to the negative electrode, and the oxygen concentration can be determined by measuring this current as a sensor output voltage.

  In such a galvanic cell type oxygen sensor, a metal piece is used as the positive electrode, the installation interval between the positive electrode and the oxygen permeable membrane is kept constant, and an electrolyte layer having a constant thickness is provided between the positive electrode and the oxygen permeable membrane. Let it form. At this time, it is difficult to keep the thickness of the electrolyte layer constant due to a change in external pressure or the like, and the sensor output may become unstable.

  In order to solve such a problem, for example, Patent Document 1 has been studied in which a positive electrode is integrally joined to one surface of an oxygen permeable membrane. Specifically, by forming a gold sputtering film obtained by sputtering gold, which is a noble metal, on one surface of the oxygen permeable film, the oxygen permeable film and the positive electrode can be integrated. Also, it is possible to prevent the sensor output from changing.

JP-A-6-109694

  As in Patent Document 1, in a galvanic cell type oxygen sensor in which a gold sputtering film is formed on one surface of an oxygen permeable film, and the oxygen permeable film and the positive electrode are integrated, the gold sputtering film is changed from the oxygen permeable film to the time course. There was a case of peeling due to deterioration. For this reason, there is a possibility that the conduction failure due to the crack of the gold sputtering film or the electrolyte enters between the oxygen permeable film and the gold sputtering film and the sensor output becomes unstable.

  In the galvanic cell type oxygen sensor described above, the electrolyte solution may leak from the gas permeable diaphragm provided in the vicinity of the gas vent in a high temperature or high humidity environment, and the sensor output decreases due to a decrease in the reaction area. There was a fear.

  Accordingly, an object of the present invention is to provide a galvanic cell type oxygen sensor that improves the durability of the gold sputtering film, stabilizes the sensor output, and prevents the electrolyte from leaking.

  In order to achieve the above object, a galvanic cell type oxygen sensor according to the present invention includes, in a casing, a positive electrode containing a noble metal, a negative electrode, an electrolytic solution in contact with the positive electrode and the negative electrode, and an electrolysis containing the electrolytic solution. A galvanic cell type oxygen sensor comprising a liquid storage part and a gas permeable diaphragm that allows a gas to be detected to permeate, the first characteristic configuration of the positive electrode being on the side of the electrolyte storage part in the positive electrode It is in the point provided with the peeling prevention means which prevents peeling.

  According to this configuration, since the electrolytic solution is not easily brought into direct contact with the positive electrode by providing the anti-exfoliation means for preventing the exfoliation of the positive electrode on the side of the electrolyte container in the positive electrode, deterioration such as separation of the positive electrode Can be prevented in advance. For example, when a gold sputtering film is formed on the side of the electrolyte container in the positive electrode and the positive electrode and the gas permeable diaphragm are integrated, the durability of the gold sputtering film is improved and the peeling is prevented. be able to.

  According to a second characteristic configuration of the galvanic cell type oxygen sensor according to the present invention, the separation preventing unit is an ion exchange unit that covers a side of the electrolyte solution storage unit in the positive electrode and transmits ions contained in the electrolyte solution. In the point.

  In this configuration, even if the peeling prevention means is an ion exchange part and the electrolyte solution storage part side of the positive electrode is covered with the ion exchange part, the ion exchange part transmits ions contained in the electrolyte solution and turns the ions into the positive electrode. Therefore, the redox reaction between the positive and negative electrodes is not hindered. Therefore, in this configuration, the durability of the positive electrode is improved even in a harsh environment such as high temperature and high humidity, and a galvanic cell type oxygen sensor with stable sensor output while maintaining sensor characteristics is obtained.

  The third characteristic configuration of the galvanic cell type oxygen sensor according to the present invention is that the ion exchange part is composed of two layers formed of a solution layer and an ion exchange membrane.

  According to this configuration, by configuring the ion exchange part with two layers, the durability of the positive electrode can be further improved as compared with the case of a single layer.

  The fourth characteristic configuration of the galvanic cell type oxygen sensor according to the present invention is that it has a portion where the ion exchange part is configured to have a smaller diameter than the positive electrode.

  For example, when an ion exchange membrane is applied to the ion exchange part, if the ion exchange membrane is smaller in diameter than the positive electrode, the ion exchange membrane is positive even if a slight misalignment occurs when the ion exchange membrane is positioned on the positive electrode. It becomes difficult to come off the position on 2. Therefore, since an error in assembling the ion exchange membrane can be allowed to some extent, the galvanic cell type oxygen sensor can be easily manufactured.

  The method for manufacturing a galvanic cell type oxygen sensor according to the present invention includes, in a casing, a positive electrode containing a noble metal, a negative electrode, an electrolytic solution in contact with the positive electrode and the negative electrode, and an electrolytic solution storage unit that stores the electrolytic solution. A gas permeable membrane oxygen sensor having a gas permeable membrane that allows the gas to be detected to permeate, wherein the characteristic configuration is that a solution having the same composition as the ion exchange membrane is dropped onto the positive electrode. There exists a point which has a dripping process and the thermocompression-bonding process of thermocompression-bonding the said ion exchange membrane.

According to this structure, the galvanic cell type oxygen sensor which comprises an ion exchange part by two layers which made one layer the solution layer and made the other layer the ion exchange membrane can be manufactured. In this case, the solution layer can be easily formed by dropping, and the ion exchange membrane is excellent in adhesion to the solution layer, so that the effect of the ion exchange portion can be ensured.
Therefore, with this configuration, it is possible to manufacture a galvanic cell type oxygen sensor in which the durability of the positive electrode is further improved and the sensor output is stable while maintaining the sensor characteristics.

It is the schematic which shows the cross section of the galvanic-cell-type oxygen sensor of this invention. It is a disassembled perspective view of the galvanic cell type oxygen sensor of this invention. It is a disassembled perspective view of the galvanic cell type oxygen sensor of this invention. It is the photograph figure which expanded the 1st water retention member and the 2nd water retention member. 1 is a schematic cross-sectional view of a main part of a galvanic cell type oxygen sensor in Example 1. FIG. 3 is a schematic cross-sectional view of a main part of a galvanic cell type oxygen sensor in Example 2. FIG. (Example 3) which is decomposed | disassembled after 15 days exposure to harsh environments, and observed the state of the gold | metal sputtering film | membrane.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the galvanic cell type oxygen sensor X of the present invention includes a positive electrode 2 containing a noble metal, a negative electrode 3, and an electrolyte solution 4 in contact with the positive electrode 2 and the negative electrode 3. And an electrolyte containing part 5 that contains the electrolyte 4 and a gas permeable diaphragm 6 that allows the gas to be detected to permeate. The positive electrode 2 is prevented from peeling on the side of the electrolyte containing part 5 in the positive electrode 2. The peeling prevention means 10 is provided. The peeling prevention means 10 is an ion exchange portion 7 that covers the electrolyte solution storage portion 5 side of the positive electrode 2 and transmits ions contained in the electrolyte solution 4.

  The casing 1 includes a casing body 1a and a lid portion 1b. Although the case where the casing 1 of this embodiment is made into a substantially cylindrical shape is demonstrated, it is not limited to this. The casing body 1 a is provided with a gas vent hole 1 c having a diameter of about 2 mm so that oxygen can be introduced into the casing 1. The lid portion 1b includes a frame portion 1b1 to be welded to a peripheral edge portion (skirt portion 1a1) of the casing body 1a, and a resin portion 1b2 made of resin disposed inside the frame portion 1b1.

The skirt portion 1a1 and the frame portion 1b1 are both formed in an annular shape and face each other, and the skirt portion 1a1 is formed by melting the protruding portion 1b3 in which the surface of the frame portion 1b1 on the skirt portion 1a1 side is protruded in an annular shape. And the frame part 1b1 can be welded. The back surface of the projecting portion 1b3 in the frame portion 1b1 is recessed in a groove shape.
In the present embodiment, the case where the skirt portion 1a1 and the frame portion 1b1 are welded will be described, but other methods (for example, caulking or the like) may be applied as long as they can be sufficiently joined. However, it is preferable to apply the above-described welding mode from the viewpoint of bonding strength and the like.

  Although the said resin part 1b2 can be comprised with PPS resin etc., it is not limited to this. The lid portion 1b (resin portion 1b2) is provided with an injection portion 1d so that the electrolytic solution 4 can be injected after the lid portion 1b is assembled to the casing body 1a. The injection portion 1d is formed in a cylindrical shape, and is formed with an opening 1d1 that protrudes outward.

  The lid 1b can be manufactured by insert molding by injecting the resin portion 1b2 into the center of the frame portion 1b1, but is not limited thereto, and the resin portion 1b2 is hot-pressed into the center of the frame portion 1b1. You may produce by hot press molding. By molding in this way, a part of the frame portion 1b1 (inserted portion 1b4) is fitted into the resin portion 1b2, and the frame portion 1b1 and the resin portion 1b2 are firmly coupled to improve the sealing degree in the casing 1. Can be made.

  The galvanic cell type oxygen sensor X can be disposed on another object such as the PC board 21 via an adhesive 20 such as an epoxy adhesive in a state where the casing main body 1a and the lid 1b are assembled. In the present embodiment, the galvanic cell type oxygen sensor X and the PC board 21 are referred to as a sensor unit A.

  The lid portion 1b (resin portion 1b2) of the present embodiment is provided with a fitting hole 1e into which a part of the negative electrode 3 (the reduced diameter portion 3a) is fitted, and a contact member that can be brought into contact with the end face of the fitted negative electrode 3 1f is provided. The side of the PC board 21 in the contact member 1 f includes a fitting protrusion 1 g that is fitted into the contact hole 21 a of the PC board 21. Metal thin films 22a, 22b, and 22c for electrical connection with the galvanic cell type oxygen sensor X are provided on the inner surface of the contact hole 21a of the PC board 21 and the galvanic cell type oxygen sensor X side and the back surface of the PC board 21. Each is arranged. The metal thin film 22b disposed on the galvanic cell type oxygen sensor X side of the PC board 21 is formed in an annular shape along the peripheral edge of the PC board 21, and is opposed to the frame part 1b1 of the lid part 1b. The shape is approximately the same.

  The fitting protrusion 1g in the contact member 1f and the contact hole 21a of the PC board 21 are electrically connected to the contact member 1f and the PC board 21 by bonding them with the conductive adhesive 8. Moreover, the negative electrode 3 and the contact member 1f are electrically connected to the lid portion 1b and the negative electrode 3 by bonding them with a conductive adhesive 8 and fixing them.

  The material of the casing body 1a and the lid portion 1b (frame portion 1b1) can be made of stainless steel, but is not limited to this, and other metals and resins can be applied. When energizing the casing body 1a and the frame portion 1b1 as electrodes, it is preferably made of metal, and if it is made of metal, evaporation of the electrolyte 4 inside can be prevented as compared with a resin.

  In the casing 1, an annular polyimide solid adhesive sheet 11, a nonwoven fabric separator 12, and a positive electrode 2 containing a noble metal are disposed in this order from the gas vent 1 c side. Since the solid adhesive sheet 11 can bring the casing 1 and the positive electrode 2 into close contact with each other, oxygen entering from the hole 1c of the casing 1 does not diffuse between the casing 1 and the positive electrode 2 and can reach the positive electrode 2 at the shortest distance. Can lead. The separator 12 may be disposed inside the solid adhesive sheet 11 with a smaller diameter than the solid adhesive sheet 11. For example, a gas-permeable porous PTFE membrane having water repellency can be used, but the separator 12 is not limited thereto. It is not something. The solid adhesive sheet 11 and the positive electrode 2 are configured to have substantially the same outer diameter.

  The solid adhesive sheet 11, the separator 12 and the positive electrode 2 are preferably fixed with a conductive adhesive 8 such as a silver-epoxy system (ECA-100). For the conductive adhesive 8, a plurality of different types of conductive adhesives may be used as appropriate in consideration of the relationship between durability temperature and manufacturing temperature. At this time, the solid adhesive sheet 11, the separator 12 and the positive electrode 2 are stacked and thermally cured, and then the side surfaces and a part of the outer periphery of the positive electrode 2 are bonded to the conductive adhesive in a state where the ion exchange part 7 is thermocompression bonded. The conductive adhesive 8 may be applied so as to be covered with 8. Accordingly, the casing main body 1a and the positive electrode 2 are bonded and fixed to the casing 1 (casing main body 1a) with the conductive adhesive 8 in a state where the solid adhesive sheet 11, the separator 12 and the positive electrode 2 are stacked. 2 is conducted.

  Therefore, when the galvanic cell type oxygen sensor X is disposed on the PC board 21 with the casing body 1a and the lid portion 1b assembled, the positive electrode 2 is electrically connected to the casing body 1a welded to the frame portion 1b1. 2 is electrically connected to the PC board 21, and the negative electrode 3 is electrically connected to the contact member 1 f provided on the lid 1 b, so that the negative electrode 3 is electrically connected to the PC board 21.

  In addition, the solid adhesive sheet 11, the separator 12, and the positive electrode 2 are stacked and thermally cured, and then the ion exchange part 7 is thermocompression bonded, and a part or the entire periphery of the side surface and the positive electrode 2 is electrically conductive adhesive. The conductive adhesive 8 may be applied so as to be covered with 8.

  In this embodiment, when the lid 1b is disposed on the PC board 21 with the casing body 1a and the lid 1b assembled, the opening 1d1 of the injection part 1d is inserted through the opening 21b of the PC board 21. It is configured.

  The positive electrode 2 is configured as a noble metal thin-film electrode having a thickness of about 1 μm, for example. As the noble metal, metals such as gold, platinum, and silver can be used. These noble metals may be provided in the form of a metal foil such as a gold foil, a platinum foil, or a silver foil, or may be provided in a form formed by sputtering on a suitable substrate. In the present embodiment, a gold sputtering film is formed by sputtering gold on the side of the electrolyte solution storage section 5 in a gas permeable diaphragm 6 (described later) that allows the gas to be detected to pass, and the positive electrode 2, the gas permeable diaphragm 6, The case where these are integrated will be described.

  A conventionally known negative electrode material can be used for the negative electrode 3, and in particular, a material containing a base metal such as lead as in this embodiment can be preferably applied. Examples of the base metal include zinc, aluminum and the like in addition to lead. The negative electrode 3 of the present embodiment has a substantially cylindrical shape, and includes a reduced diameter portion 3a whose diameter is partially reduced and a large diameter portion 3b that is larger in diameter than the reduced diameter portion 3a and is surrounded by the electrolyte container 5. However, the present invention is not particularly limited to such a mode as long as the negative electrode 3 is not misaligned during sensor assembly and use of the sensor.

The electrolytic solution 4 is stored in the electrolytic solution storage unit 5 so as to be in contact with the positive electrode 2 and the negative electrode 3. A water retention member 9 for holding the electrolyte solution 4 is disposed in the electrolyte solution storage unit 5. In the present embodiment, a case will be described in which the first water retaining member 9a and the second water retaining member 9b are disposed in the electrolytic solution storage unit 5 and the water retaining members 9a and 9b are impregnated with the electrolytic solution 4. The first water retention member 9a is formed in a plate shape and disposed on the positive electrode 2 side, and the second water retention member 9b is adjacent to the first water retention member 9a, surrounds at least a part of the negative electrode 3, and contacts the negative electrode 3. It is formed in an annular shape. In the present embodiment, the second water retaining member 9b describes a mode in which the large-diameter portion 3b of the negative electrode 3 is surrounded and is in contact with the negative electrode 3. However, the present invention is not limited to this, and the volume of the electrolyte solution storage unit 5 is considered. The second water retaining member 9b may surround the reduced diameter portion 3a and the large diameter portion 3b of the negative electrode 3.
The first water retaining member 9a and the second water retaining member 9b are part of the negative electrode 3 depending on the material of the first water retaining member 9a when the casing main body 1a and the lid portion 1b are assembled (FIG. 1). However, it will become a mode which sinks into the 1st water retention member 9a.

  Moreover, in this embodiment, the 2nd water retention member 9b is comprised with the film body whose bulk density is lower than the 1st water retention member 9a (FIG. 4). In other words, the second water retaining member 9b can be a coarser film than the first water retaining member 9a. For example, the fibers constituting the second water retention member 9b are preferably thicker than the fibers constituting the first water retention member 9a and having a larger gap between the fibers. These water retaining members 9a and 9b can use film bodies having a thickness of about 0.25 to 3 mm.

As such a water retention member 9, for example, the first water retention member 9a can be a film body mainly composed of ceramic fibers. The bulk density of the film body should be about 0.18 g / cm ³ and the space ratio should be about 90%. Specifically, MC paper (manufactured by Nippon Sheet Glass Co., Ltd.) can be used. It is not limited to.

The second water retaining member 9b can be a resin film such as a polyethylene / polypropylene polymer. The bulk density of the film body is preferably about 0.08 g / cm ³ and the space ratio is about 90%. Specifically, OR-125 (manufactured by Asahi Textile Industry Co., Ltd.) can be used. However, the present invention is not limited to this.

As the electrolytic solution 4, both a basic aqueous solution and an acidic aqueous solution can be used. For example, an electrolytic solution applicable to a conventional galvanic cell type oxygen sensor such as a KOH aqueous solution as a basic aqueous solution and a buffer solution of CH ₃ COOH and CH ₃ COOK as an acidic aqueous solution can be used.

  The gas permeable diaphragm 6 that allows the gas to be detected to permeate is a diaphragm that selectively permeates oxygen and does not permeate the electrolytic solution 4, and partitions the outside and the inside of the container 1. The material of the gas permeable diaphragm 6 is not particularly limited as long as it does not transmit the electrolyte solution 4 and has oxygen permeation performance. For example, tetrafluoroethylene / hexafluoropropylene copolymer resin (FEP), tetrafluoroethylene, A conventionally well-known thing, such as a perfluoroalkyl vinyl ether copolymer (PFA), is applicable.

  In the galvanic cell type oxygen sensor X of the present invention, the side of the electrolyte container 5 in the positive electrode 2 is covered with an ion exchange unit 7 that transmits ions contained in the electrolyte 4. In this invention, what is necessary is just to make it the aspect which covers the electrolyte solution accommodating part 5 side with the ion exchange part 7 in the positive electrode 2 at least. The ion exchange part 7 can use an ion exchange membrane, for example, and when the electrolyte solution 4 is a basic aqueous solution, an anion exchange membrane can be used. At this time, for example, an anion exchange membrane using a quaternary ammonium salt can be used as the ion exchange membrane. Further, when the electrolytic solution 4 is an acidic aqueous solution, a cation exchange membrane may be used. Specifically, the ion exchange membrane is Nafion (registered trademark: manufactured by DuPont), Aciplex (registered trademark: manufactured by Asahi Kasei), Flemion (registered trademark: manufactured by Asahi Glass), Yuasa graft membrane (manufactured by Yuasa Membrane System) However, it is not limited to these.

  In addition to the ion exchange membrane, a form in which the sputtering membrane is not directly buffered, for example, hydrophilic porous polyethylene (Polymic / registered trademark: manufactured by Nippon Sheet Glass Co., Ltd.), hydrophilic porous polyolefin, hydrophilic porous PTFE, cellophane. (Phullamura Chemical Co., Ltd.), papillon (registered trademark: manufactured by Sanki Co., Ltd.), etc. can be brought into close contact with the upper surface of the sputtered film to provide the peeling prevention means 10.

  Thus, by covering the side of the electrolyte container 5 in the positive electrode 2 with the ion exchange unit 7, it is difficult for the electrolyte 4 to come into direct contact with the positive electrode 2, thereby preventing the positive electrode 2 from being deteriorated. it can. In the case where the gold sputtering film is formed and the positive electrode 2 and the gas permeable diaphragm 6 are integrated as in the present embodiment, the durability of the gold sputtering film is improved and the peeling is prevented in advance. Can do. At this time, even if the positive electrode 2 is covered with the ion exchange part 7, the ion exchange part 7 can pass ions such as hydroxide ions contained in the electrolytic solution 4 and supply the ions to the positive electrode 2. It does not interfere with the redox reaction between the positive and negative electrodes. Therefore, in this configuration, a galvanic cell type oxygen sensor having a stable sensor output while maintaining sensor characteristics is obtained.

  The ion exchange part 7 can be composed of a plurality of layers. In this embodiment, the case where the ion exchange part 7 is comprised by two layers is demonstrated. As the two layers, both layers may be the ion exchange membrane 7, one layer is a layer to which a resin solution or a Nafion solution having the same composition as the ion exchange membrane 7 is applied, and the other layer is the ion exchange membrane 7. It is good. When a Nafion solution is used, the Nafion solution has a concentration of 5 to 20 wt%, and the solvent may be a mixture of lower alcohol and pure water (15 to 34%) or pure water. When one layer is a solution layer 7a such as a resin solution and the other layer is an ion exchange membrane 7b as in this configuration, the adhesiveness of the ion exchange membrane 7b is improved, so that the effect of the ion exchange portion 7 is ensured. Can be.

  When one layer is the solution layer 7a and the other layer is the ion exchange membrane 7b, a dropping step of dropping a solution having the same composition as the ion exchange membrane 7b on the positive electrode 2 and an ion exchange membrane 7b The positive electrode 2 can be covered with the ion exchange part 7 by performing the thermocompression bonding process of thermocompression bonding. In the dropping step, an appropriate amount (for example, 5 to 100 μL) of the solution may be dropped onto the positive electrode 2. What is necessary is just to perform the timing which performs a dripping process, after overlapping the solid adhesive sheet 11, the separator 12, and the positive electrode 2, and making it thermoset. Although this embodiment demonstrates the case where the ion exchange membrane 7b is thermocompression-bonded (thermocompression-bonding process) after a dripping process, it can also be set as the aspect without the ion-exchange membrane 7b. Thereafter, the conductive adhesive 8 may be applied so that the conductive adhesive 8 covers a part or the entire periphery of the side surface and the outer edge of the positive electrode 2 on the side of the electrolyte container 5. In this case, in the ion exchange part 7 and the positive electrode 2, the ion exchange part 7 may be configured to have a portion configured to have a smaller diameter than the positive electrode 2. That is, the ion exchange membrane 7 b can be made smaller in diameter than the positive electrode 2. Moreover, by covering with the conductive adhesive 8, it becomes difficult for the electrolytic solution to enter the interface between the ion exchange part 7 and the gold sputtering film.

  At this time, since the conductive adhesive 8 can cover a part of the side surface and the outer periphery of the positive electrode 2 or the entire periphery, the solid adhesive sheet 11, the separator 12, and the positive electrode 2 can be firmly fixed. In addition, since the electrolyte solution 4 impregnated in the ion exchange part 7 can be reliably cut off at the position of the conductive adhesive 8 covering a part of the outer periphery of the positive electrode 2 or the entire periphery, the electrolyte solution 4 is solid-bonded. It becomes difficult to contact the sheet 11, and leakage of the electrolyte solution 4 can be prevented in advance.

  Further, in the ion exchange part 7, when the ion exchange membrane 7 b has a smaller diameter than the positive electrode 2, even if a slight misalignment occurs when the ion exchange membrane 7 b is positioned on the positive electrode 2 during thermocompression bonding, The exchange membrane 7b is difficult to be removed from the position on the positive electrode 2. For this reason, an error in assembling the ion exchange membrane 7b can be allowed to some extent, so that the manufacturing becomes easy.

  After performing the dropping step, a drying step for drying the solution may be performed. This drying may be natural drying near room temperature, or may be performed using a dryer or the like. The drying temperature and time are not particularly limited, such as several hours around 120 ° C., and can be set as appropriate as long as the temperature does not change the properties of the solution. In addition, the thermocompression bonding step can be performed, for example, at a temperature of about 100 to 120 ° C. for 1.5 to 5 minutes, but is not limited to these as long as the temperature does not change the properties of the ion exchange membrane 7b. Absent. In addition, after apply | coating the conductive adhesive 8, it is good also as natural drying, and you may dry about 1 to several hours at the temperature of about 140 degreeC using a drying machine etc.

  In addition, the solid adhesive sheet 11, the separator 12 and the positive electrode 2 are stacked and thermally cured, and then the conductive adhesive 8 is applied, and then the dropping process and the thermocompression bonding process are performed to cover the positive electrode 2 with the ion exchange unit 7. May be.

  As described above, by configuring the ion exchange part 7 with two layers (a plurality of layers), durability (prevention of deterioration of the positive electrode 2) can be further improved as compared with the case of a single layer.

[Example 1]
Examples of the present invention will be described.
The case where the ion exchange part 7 is comprised by two layers is demonstrated when manufacturing the galvanic cell type oxygen sensor X (outside diameter 15mm, height 10mm) of this invention. In this example, one layer was a solution layer 7a to which a Nafion solution was applied, and the other layer was an ion exchange membrane 7b (Nafion). After solid adhesive sheet 11, separator 12, and positive electrode 2 on which a gold sputtering film having a thickness of about 1 μm is formed in advance by sputtering on gas permeable diaphragm 6 in a conventional manner are stacked on casing body 1 a and thermally cured. A dropping step of dropping 10 μL of Nafion solution onto the positive electrode 2 was performed to form a solution layer 7a. Thereafter, after natural drying for 3 hours or more, a thermocompression bonding process was performed in which the ion exchange membrane 7b was pressure-bonded at 110 ° C. for 2 minutes to form the ion exchange part 7 (FIG. 5). After that, the conductive adhesive 8 is applied so as to cover a part or the entire circumference of the side surface and the outer edge of the positive electrode 2 on the side of the electrolytic solution housing portion 5 with the conductive adhesive 8 and fired at 140 ° C. for 1 hour. did.

  In this case, since the thickness of the ion exchange part 7 covering the positive electrode 2 can be formed uniformly, the ion exchange part 7 can be peeled off and deteriorated compared with the case where the thickness of the ion exchange part 7 is uneven. Can be prevented.

  Thereafter, MC paper (manufactured by Nippon Sheet Glass Co., Ltd.) as the first water retention member 9a, OR-125 as the second water retention member 9b, and the negative electrode 3 made of lead were assembled. In this state, the peripheral edge portion of the casing body 1a and the lid portion 1b are welded and assembled, the electrolyte solution (acidic aqueous solution) 4 is injected from the injection portion 1d, and then heated and melted to open the opening portion 1d1 of the injection portion 1d. Sealed and disposed on the PC board 21 via the epoxy adhesive 20 as shown in FIG.

  In the present embodiment, in the ion exchange part 7 and the positive electrode 2, the ion exchange membrane 7 b is configured to have a smaller diameter than the positive electrode 2.

[Example 2]
The galvanic cell type oxygen sensor X in this example is obtained by stacking the solid adhesive sheet 11, the separator 12, and the positive electrode 2 on which a gold sputtering film is deposited and thermosetting them, and then outer sides of these side surfaces and the electrolyte container 5 side. A part or the whole circumference was applied so as to be covered with the conductive adhesive 8 (FIG. 6). Thereafter, the solution layer 7a and the ion exchange membrane 7b were stacked on the casing body 1a and thermocompression bonded. Other conditions were performed according to Example 1.

Example 3
The ion exchange part 7 is not formed in the galvanic cell type oxygen sensor X of Example 1 and the galvanic cell type oxygen sensor X of Example 1 as a comparative example (the first water retaining member 9a and the second water retaining member 9b are not provided). Using the sensor of the aspect, it was decomposed after being exposed to a harsh environment for 15 days, and the state of the gold sputtering film was observed. The harsh environment in this example was a condition in which a heat cycle of −25 to 55 ° C. was repeated. The results are shown in FIG.

  As a result, in the galvanic cell type oxygen sensor X of Example 1, no deterioration such as peeling of the gold sputtering film was observed (FIG. 7A). On the other hand, in the galvanic cell type oxygen sensor of the comparative example, degradation such as peeling was observed near the center of the gold sputtering film (FIG. 7B: arrow portion). This was considered because the electrolyte solution 4 was in direct contact with the positive electrode 2 (gold sputtering film).

  Therefore, with the galvanic cell type oxygen sensor X of the present invention, even if it is a severe ring as described above, deterioration such as peeling of the gold sputtering film is not recognized, and durability is improved, thereby stabilizing the sensor output. It was recognized.

  The present invention provides a casing having a positive electrode containing a noble metal, a negative electrode, an electrolytic solution in contact with the positive electrode and the negative electrode, an electrolytic solution containing part for containing the electrolytic solution, and a gas permeability that allows the gas to be detected to permeate. And a galvanic cell oxygen sensor equipped with a diaphragm.

X Galvanic cell type oxygen sensor 1 Casing 2 Positive electrode 3 Negative electrode 4 Electrolyte 5 Electrolyte container 6 Gas permeable diaphragm 7 Ion exchange part 10 Peeling prevention means

Claims (5)

In the casing, a positive electrode containing a noble metal, a negative electrode, an electrolytic solution in contact with the positive electrode and the negative electrode, an electrolytic solution storage unit that stores the electrolytic solution, and a gas-permeable diaphragm that allows the gas to be detected to permeate. A galvanic cell type oxygen sensor provided,
A galvanic cell type oxygen sensor provided with a peeling prevention means for preventing peeling of the positive electrode on the side of the electrolytic solution housing portion in the positive electrode.   2. The galvanic cell type oxygen sensor according to claim 1, wherein the peeling prevention unit is an ion exchange portion that covers the electrolyte solution storage portion side of the positive electrode and transmits ions contained in the electrolyte solution.   The galvanic cell type oxygen sensor according to claim 2, wherein the ion exchange part is composed of two layers formed of a solution layer and an ion exchange membrane.   The galvanic cell type oxygen sensor according to claim 2 or 3, wherein the ion exchange part has a portion configured to have a smaller diameter than the positive electrode. In the casing, a positive electrode containing a noble metal, a negative electrode, an electrolytic solution in contact with the positive electrode and the negative electrode, an electrolytic solution storage unit that stores the electrolytic solution, and a gas-permeable diaphragm that allows the gas to be detected to permeate. A galvanic cell type oxygen sensor manufacturing method comprising:
A method for producing a galvanic cell type oxygen sensor, comprising: a dropping step of dropping a solution having the same composition as the ion exchange membrane onto the positive electrode; and a thermocompression bonding step of thermocompression bonding the ion exchange membrane.