JP2000021415A - Conductive porous body and metallic porous body using the same, and electrode plate for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive porous body capable of manufacturing a metal porous body having a low electric resistance value with excellent productivity and production efficiency, a metal porous body having a low electrical resistance value and capable of improving the charging and discharging efficiency in case of using it as an electrode plate for battery, and an electrode plate for battery having superior charging and discharging efficiency. SOLUTION: A conductive porous body is formed by forming a surface of a porous body as a core material made of the synthetic resin, having a continuous hole structure with a conductive layer of the aggregate of silver fine grains. The metal porous body is formed by forming a surface of the conductive porous body with a continuous plate layer with electroplating using the conductive porous body for negative electrode. Furthermore, an electrode plate for battery is formed of the metal porous body as the main body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a conductive porous body made of a synthetic resin porous body having a continuous pore structure, the surface of which is made conductive, and the conductive porous body manufactured using the conductive porous body as an intermediate material. In particular, the present invention relates to a metal porous body suitably used for a battery electrode plate such as an alkaline secondary battery, and a battery electrode plate using such a metal porous body.

[0002]

2. Description of the Related Art Alkaline secondary batteries are highly reliable and can be reduced in size and weight. Therefore, various types of alkaline secondary batteries are available, from small ones for portable equipment to large ones for industrial and large equipment. It is often used as a power source for equipment.

There are many types of alkaline secondary batteries depending on the combination of positive and negative electrodes. In most cases, a nickel electrode is used as a positive electrode. As the negative electrode, there are a cadmium electrode, a zinc electrode, an iron electrode, a hydrogen electrode, and the like. Among these, a cadmium electrode is the most common, but a hydrogen electrode using a hydrogen storage alloy as an active material also has a high capacity. Attention has been paid to low pollution.

At first, the so-called pocket type was used as the nickel electrode.
A battery filled with a large number of active material particles for the positive electrode, such as nickel hydroxide, in the gap of the current-collecting electrode plate made of a conductive material such as nickel and porous It is generalized because it is possible and can improve the characteristics of the battery as compared with the pocket type. Also, as the cadmium electrode and the hydrogen electrode, a material in which a large number of negative electrode active material particles such as cadmium and a hydrogen storage alloy are filled in the space of the porous electrode plate as described above is used.

Conventionally, a sintered body obtained by sintering nickel powder has been used as such a porous electrode plate. However, recently, since the amount of active material particles to be filled can be larger than that of the sintered body, a battery is required. As a material suitable for increasing the capacity, a metal porous body manufactured by using a porous body of a synthetic resin having a continuous pore structure and a large porosity (such as polyurethane foam) as a core material is being put to practical use.

[0006] Generally, the above-mentioned porous metal material is obtained by treating the surface of a core material with a catalyst such as palladium chloride and then performing electroless plating such as electroless nickel plating, or containing carbon fine particles such as graphite. After applying a binder resin solution and drying it to make it conductive, the conductive porous body (conductive porous body) is used as a cathode to electroplate a metal, particularly nickel, and the like, It is manufactured by forming a continuous metal plating layer (such as a nickel plating layer) and, if necessary, performing a heat treatment to remove the core material.

[0007]

However, as described above, the conductive porous body in which the surface of the porous body is made conductive by electroless plating is not easy to handle. For example, (1) continuous production Using equipment, when continuously producing a metal porous body through the conductive porous body from the core material,
Bending or stretching in the length direction by tension, which is added to the conductive porous body in sending to the next step of the electroplating step, (2) a predetermined amount of the manufactured conductive porous body,
In order to perform electroplating at one time in the next process, winding to form a roll, hoop, etc., (3) A predetermined amount of core material previously wound into a roll, hoop, etc. In order to continuously electroplate the produced conductive porous body in the next step after conducting treatment, the unwinding process when unwinding from the roll or hoop is performed. , And the growth rate of the metal plating layer such as nickel in the electroplating step is reduced, and as a result, the productivity and production efficiency of the porous metal body may be reduced.

That is, the conductive layer formed on the surface of the core material by electroless plating is a very thin and continuous metal film of about 0.1 μm in the case of electroless nickel plating, for example. When the porous body is bent, stretched, wound, deformed such as unreeling, it is easily broken or broken, and when such cracks or breaks occur, the conductivity of the conductive porous body decreases, As described above, the electric resistance value greatly increases, and as a result, the growth rate of the metal plating layer of nickel or the like in the electroplating step decreases.

Therefore, for example, it has been studied to reduce the feed rate or to increase the curvature of the bend or winding in order to suppress the tension applied to the conductive porous body.
In such a case, it is necessary to (a) reduce the productivity and production efficiency of the porous metal body, and (b) require more space for production equipment, transportation and storage equipment. It turned out to be problematic.

The conductive layer formed on the surface of the core material by the most common electroless nickel plating as the above-mentioned electroless plating contains phosphorus (P) contained in the plating bath. After electroplating a metal plating layer such as nickel, heat treatment to remove the core material, etc.
As a result of the diffusion of the phosphorus into the metal plating layer, the electric resistance value of the manufactured porous metal body increases, and for example, when used as an electrode plate for a battery, the charge / discharge efficiency decreases. there were.

[0011] Further, the conductive porous body whose surface is made conductive by carbon fine particles as described above also causes a crack or the like of the binder resin by being particularly stretched. In addition to the large increase in the electric resistance value, such a conductive porous body has a very low growth rate of the metal plating layer in the electroplating because the electric resistance value of the carbon itself is much higher than the metal in the first place. In addition, there is a problem that productivity and production efficiency of the porous metal body are low.

[0012] The main object of the present invention is to provide a metal porous layer having a high growth rate in electroplating, being easy to handle, and hardly reducing the growth rate even when a large deformation is applied. An object of the present invention is to provide a novel conductive porous body which is excellent in productivity and production efficiency and can produce an excellent metal porous body having a low electric resistance value.

Another object of the present invention is to improve the charge / discharge efficiency when used as an electrode plate for a battery, for example, because it is manufactured from such a conductive porous body and has a low electric resistance. To provide a novel metal porous body.

Still another object of the present invention is to provide a novel battery electrode plate which is formed of such a porous metal body and has excellent charge / discharge efficiency.

[0015]

Means for Solving the Problems In order to solve the above problems,
The present inventors have conducted various studies on conductive materials for making the surface of a synthetic resin core material conductive.

As a result, although a part of the silver conductive layer formed by the electroless silver plating has a high electric resistance value in a dry state, the growth rate of the metal plating layer in the next electroplating step is low. Highly and surprisingly, this growth rate does not change much after the above-mentioned various deformations are applied to the conductive porous body, so that the metal porous body can be produced with high productivity and high production efficiency. It has been found that it has excellent properties which were previously unknown and which can be manufactured.

Therefore, as a result of further study focusing on the microstructure of the silver conductive layer, it was found that the above-described excellent characteristics can be exhibited when the conductive layer is made of an aggregate of silver fine particles. And completed the present invention.

That is, the conductive porous body of the present invention comprises, as a core material, a porous body made of synthetic resin having a continuous pore structure.
On the surface thereof, a conductive layer composed of an aggregate of silver fine particles is formed.

In the metal porous body of the present invention, a continuous metal plating layer is formed on the surface of the conductive porous body by electroplating using the conductive porous body of the present invention as a cathode. It is characterized by the following.

The metal porous body may be heat-treated after forming the metal plating layer to remove the synthetic resin core.

Further, an electrode plate for a battery according to the present invention is characterized by being mainly composed of the porous metal body of the present invention.

In the present invention, the silver fine particles constituting the conductive layer are stable to water and oxygen as characteristics of silver itself, and the surface thereof is hardly oxidized. The state is maintained.

Therefore, the conductive layer made of the aggregate of silver fine particles has a high electric resistance in a dry state due to poor electric conduction between the fine particles, but is immersed in an electroplating bath in the electroplating step. Then, the growth rate of the metal plating layer is high as described above, probably because the electric resistance between the fine particles is maintained through the plating solution penetrating into the fine gaps between the fine particles and the electric resistance value decreases.

Moreover, even if the conductive porous body is deformed, the structure of the conductive layer and the mechanism of electric conduction in the state of being immersed in the electroplating bath are hardly affected. The growth rate of the metal plating layer hardly decreases, and the metal porous body can be manufactured with high productivity and high production efficiency.

In addition, in the produced porous metal body, for example, when the core material is removed by heat treatment, a small amount of silver originating from the conductive layer of the silver fine particles described above is contained as a metal plating layer as an impurity. Although the electric resistance slightly increases in comparison with a pure metal simple substance (for example, nickel simple substance) due to the diffusion into the inside, the degree of the increase is due to the increase in the electric resistance value due to the diffusion of phosphorus from the electroless nickel plating layer. Since it is significantly smaller than the above, it hardly affects the overall electric resistance value of the porous metal body.

As a result, according to the present invention, a conductive porous body which is excellent in productivity and production efficiency of a porous metal body and can produce an excellent porous metal body having a low electric resistance value; A metal porous body which has a low electric resistance value because it is manufactured from such a conductive porous body and which can improve the charge / discharge efficiency thereof when used as an electrode plate for a battery, and a metal porous body such as this Thus, an electrode plate for a battery having excellent charge / discharge efficiency can be obtained.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below.

First, the conductive porous body of the present invention will be described.

[0029] Such a conductive porous body is, as described above,
A porous body made of a synthetic resin having a continuous pore structure is used as a core material, and a conductive layer made of an aggregate of silver fine particles is formed on the surface thereof.

As the core material, any of various conventionally known porous bodies having a continuous pore structure formed of a synthetic resin can be used.

That is, a foam having a continuous pore structure therein and itself having a three-dimensional network structure, a nonwoven fabric made of synthetic resin fibers, and a woven fabric woven of synthetic resin fibers are exemplified.

Specific examples of the foam include the above-mentioned polyurethane foam and foams of a thermoplastic resin such as polystyrene, polyethylene, polypropylene, and polyvinyl chloride.

The synthetic resin fibers constituting the nonwoven fabric and the woven fabric are, for example, polyethylene,
Various known synthetic resin fibers such as polyester, polypropylene, and nylon can be used.

The metal porous body produced from the conductive porous body of the present invention is a metal porous body which remains without removing a core material as described later, and is used for an alkaline secondary battery. When used as an electrode plate, it is necessary that such a core material has excellent resistance to the strong alkali of the alkaline electrolyte, that is, excellent alkali resistance.

Specifically, for example, the standard ASTM D543-63 defined by the American Society for Testing and Materials (ASTM).
In the chemical resistance test during T, those which can be evaluated as G (good) or more, particularly E (excellent), with respect to a strong alkaline solution having a pH of 11 or more corresponding to an alkaline electrolyte are preferable.

As such a core material having excellent alkali resistance, a porous body formed of a polyolefin such as polyethylene or polypropylene is preferable.

Specific examples thereof include, but are not limited to, cross-linking of single fibers made of polyolefin having a diameter of about 10 to 40 μm into a nonwoven fabric having an average pore diameter of about 0.6 mm or less. A porous body having such a shape as to be joined at a portion and further extended in one direction [for example, trade name RF manufactured by Hitachi Chemical Co., Ltd.
-30].

The metal porous body produced from the conductive porous body of the present invention has a core material removed as described later, or a metal porous body left without removing the core material. However, when used for other purposes other than the electrode plate for an alkaline secondary battery, the core material does not need to have high alkali resistance as described above, but rather is subjected to heat treatment. Considering ease of removal, cost, etc., it is preferable to use a general-purpose porous body such as polyurethane foam as the core material.

The thickness, average pore diameter, porosity, etc. of the core material may be appropriately set according to the use of the porous metal body.

The conductive layer formed on the surface of the core material needs to be formed of an aggregate of silver fine particles as described above.

Although the size of the silver fine particles is not particularly limited, as described above, in consideration of the effect of improving the growth rate of the metal plating layer in the electroplating step, the smaller the particle size, the better. This is because the smaller the particle size of the silver fine particles, the smaller the gap between the fine particles described above, and the better the function of maintaining the electric conduction between the fine particles by the plating solution penetrating the gap. Can be

The specific range of the particle size of the silver fine particles is not particularly limited, but is preferably about 0.5 μm or less in terms of average particle diameter.

When the average particle size of the silver fine particles is 0.5 μm or less, as is clear from the results of Examples 1 and 2 described later, the growth rate of the metal plating layer in the electroplating step can be improved. it can. The lower limit of the range of the average particle diameter is not particularly limited, but may be about 0.
It is preferably about 01 μm.

The average particle diameter of the silver fine particles is 0.01 μm.
Below, the conductive layer behaves more like a continuous silver layer, rather than as an aggregate of silver fine particles, and the conductive porous body is deformed by the deformation of the conductive porous body. Further, cracks or breaks larger than the gaps between the silver fine particles may occur, and the growth rate of the metal plating layer in the electroplating step may be significantly reduced.

The average particle size of the silver fine particles is as described above.
Taking into account the characteristics specific to the conductive layer made of an aggregate of silver fine particles, 0.05 to 0.2 μm
It is preferably about 0.07 to 0.2 μm.

Although the thickness of the conductive layer is not particularly limited in the present invention, it is expressed as a basis weight (g / m ² ) indicating the amount of silver (g) deposited per m ^{2 of} the core material. It is preferably about 7 g / m ² .

When the basis weight of the conductive layer is less than the above range,
Because sufficient conductivity cannot be given to the core material,
The growth rate of the metal plating layer in the electroplating step may be reduced.

On the other hand, when the conductive layer is formed by, for example, the electroless silver plating method described below, the basis weight of the conductive layer and the particle size of the silver fine particles constituting the conductive layer are substantially proportional to each other. Therefore, when the basis weight of the conductive layer exceeds the above range, the silver fine particles have a mean particle size of 0.1 to 0.3.
There is a possibility that the growth rate of the metal plating layer in the electroplating step may be reduced because the thickness is larger than the preferable range of 5 μm or less.

The weight per unit area of the conductive layer should be within the above range, especially 2-5
It is preferably about g / m ² .

In order to form a conductive layer composed of an aggregate of silver fine particles on the surface of the core material, the electroless silver plating method is employed as described above.

The electroless silver plating method means that an ammoniacal solution of silver nitrate (silver solution) is treated with an aldehyde such as formalin,
Aqueous glucose solution, Rochelle salt, reaction product of Rochelle salt and silver nitrate, glyoxal, hydrazine sulfate, boiled mixture of Rochelle salt and ice sugar, mixed with reducing agents such as a solution of sugar converted with a small amount of nitric acid It is based on a so-called silver mirror reaction for reducing and depositing silver.

However, in a general silver mirror reaction, the reaction proceeds from the moment the silver solution and the reducing agent are mixed, and
Depending on the reaction temperature, the reaction is completed after about several tens of seconds, and many of the conductive layers thus obtained are not aggregates of silver fine particles required in the present invention,
It simply becomes a continuous film.

If the composition of the bath and the conditions of the reaction are carefully selected, even a normal silver mirror reaction can be performed, for example, in Example 3 described later.
As shown in the above, a conductive layer composed of an aggregate of silver fine particles can be formed, and such a conductive layer is also included in the scope of the present invention.

However, as is evident from the results of Example 3, the conductive layer thus formed has an average particle diameter of the silver fine particles within the above-mentioned preferred range (0.5 μm or less). Therefore, the growth rate of the metal plating layer in the electroplating step tends to slightly decrease.

In the ordinary silver mirror reaction, as described above, the reaction proceeds from the moment the silver liquid and the reducing agent are mixed, and the reaction is completed after about several tens of seconds.
For example, it is not easy to form a uniform conductive layer on the entire surface of a sheet-shaped core material while continuously feeding it as described above, or in a state of being wound in a roll or hoop shape. There is also a problem that implementation is difficult.

Accordingly, the present inventors have developed a new non-conductive layer capable of uniformly and continuously forming a conductive layer in which the average particle diameter of silver fine particles is 0.5 μm or less, for example, on the surface of a sheet-shaped core material. Various studies were made on the composition of the electrolytic silver plating bath.

As a result, when the aromatic iodine compound and the amino acid are added as stabilizers, the silver solution is stabilized, and even after mixing with the reducing agent, silver does not precipitate for several weeks or more at room temperature even after mixing with the reducing agent. The electroless silver plating bath has a function of gradually depositing silver in fine particles only when it comes into contact with the surface of the core material to which tin is adsorbed as a sensitizing treatment, which has not been known until now. Have found a new fact.

Then, by using the above electroless silver plating bath, as shown in Examples 1 and 2 described below, a conductive layer having an average particle diameter of silver fine particles of 0.5 μm or less was formed on a sheet. Successfully and uniformly formed on the surface of the core material.

Among the stabilizers added to the silver plating bath, examples of the aromatic iodine compound include iodobenzene and diiodosalicyl, and examples of the amino acid include glycine, alanine and aminoacetic acid. . The aromatic iodine compound and the amino acid are preferably used in a molar ratio of 1: 1.

As the silver liquor and the reducing agent constituting the bath together with the above-mentioned stabilizer, the same ones as in the prior art can be used.
That is, as the silver liquid, an ammoniacal solution of silver nitrate can be mentioned, and as the reducing agent, aldehydes such as formalin, an aqueous solution of glucose, Rochelle salt, a reaction product of Rochelle salt and silver nitrate, glyoxal, hydrazine sulfate, Rochelle salt Examples thereof include a mixture obtained by boiling a mixture of ice sugar and a solution obtained by converting sugar with a small amount of nitric acid.

In the electroless silver plating using the above silver plating bath, the particle size of the silver fine particles formed is proportional to the plating reaction rate, that is, the deposition rate of silver fine particles, and time. To control the deposition rate, the pH of the bath
It is clear from the investigations of the inventors that the liquid temperature may be changed. That is, it has been confirmed that the higher the pH of the bath (the bath is made alkaline) and the higher the liquid temperature, the higher the deposition rate.

Therefore, the pH and temperature of the above-mentioned bath and the core material to the bath are adjusted in accordance with the average particle size of the target silver fine particles and in accordance with the type of bath, particularly the type and concentration of the reducing agent. It is preferable to set the immersion time.

The specific numerical range is not particularly limited, and although the optimum value varies depending on the type and concentration of the reducing agent as described above, the pH of the bath is usually about 9%.
~ 11, temperature about 30 ~ 50 ° C, immersion time 2 ~
Preferably, it is about 15 minutes.

As described above, the conductive porous body of the present invention provided with the conductive layer composed of the aggregate of silver fine particles has a high electric resistance in a dry state as described above. The growth rate of the metal plating layer in the process is high, and since this growth rate does not change much after the above-described various deformations are applied to the conductive porous body, the metal porous body can be efficiently formed. It has excellent characteristics that it can be manufactured with high productivity.

According to the conductive porous body of the present invention, the conductive layer is formed of silver fine particles as described above.
Since there is no possibility that the electric resistance value of the metal plating layer formed in the subsequent electroplating step is significantly improved, there is also an advantage that an excellent metal porous body having a low electric resistance value can be manufactured.

Next, the metal porous body of the present invention will be described.

As described above, such a metal porous body is continuously plated on the surface of the conductive porous body by electroplating using the conductive porous body of the present invention as a cathode.
It is constituted by forming a single layer or a multilayer metal plating layer of two or more layers made of a kind or two or more kinds of metals.

For example, a nickel-plated metal plating layer having a single-layer structure is formed between the two electrodes by dipping the conductive porous body in a nickel electroplating bath together with a suitable anode such as a nickel plate. It is formed by applying a voltage and electroplating.

The metal plating layer may be formed of a metal (for example, nickel) required for an electrode plate at least on the surface thereof. One or more layers may be formed, and a multi-layer structure in which a surface plating layer of nickel or the like is stacked on the outermost layer may be used.

The thickness of the metal plating layer is not particularly limited in the present invention, but is preferably about 5 to 30 μm, and more preferably 5 to 10 μm, in consideration of the strength and resistance value of the metal plating layer.
More preferably, it is about μm. The thickness of such a metal plating layer is, of course, its own thickness in the case of the above-described metal plating layer having a single-layer structure, but in the case of a metal plating layer having a multilayer structure of two or more layers, the thickness of each layer is Is the sum of

Also, in the porous metal body of the present invention, as described above, after the formation of the metal plating layer, the whole is firstly oxidized in the air for oxidizing and thermally decomposing the synthetic resin, and then oxidized. A heat treatment at a high temperature of about 1000 ° C. in a non-oxidizing atmosphere such as hydrogen gas to reduce the nonconductive metal plating layer, thereby completely reducing the core material, that is, the synthetic resin constituting the core material. May be removed until no carbon originating from is detected.

At this time, as described above, in the conventional electroless nickel plating layer, there is a problem that phosphorus contained in the layer diffuses into the metal plating layer and the electric resistance value of the porous metal body increases. Occurs.

On the other hand, the metal porous body of the present invention has a low electric resistance because it is manufactured using the conductive porous body of the present invention as an intermediate material as described above. It has excellent characteristics that, when used, its charge / discharge efficiency can be improved.

Next, the battery electrode plate of the present invention will be described.

Such an electrode plate is mainly composed of the porous metal body of the present invention. That is, the metal porous body produced by electroplating using the conductive porous body of the present invention as a cathode, as it is, or with the core material removed by heat treatment as described above, as a battery electrode plate used.

It is preferable that the metal porous body as the electrode plate has a porosity of about 50% or more.

If the porosity is less than the above range, the amount of the active material that can be held in the pores having the continuous pore structure becomes small, and the battery may not be able to have a high capacity.

The porosity is preferably 9 within the above range.
It is preferably at most 9%.

If the porosity exceeds this range, the overall strength of the porous metal body may be significantly reduced, making it impossible to use it as an electrode plate.

The porosity is more preferably within a range from 90 to 93%, especially in the above range, in consideration of the balance between the above-mentioned properties.

Since the electrode plate of the present invention is mainly composed of the porous metal body of the present invention as described above, it has excellent charge / discharge efficiency.
It is suitably used for secondary batteries and the like. Especially for alkaline-hydrogen secondary batteries, which are being developed as power supply batteries for hybrid vehicles, electric vehicles, etc., which need to carry a large current of about 100 A in the size of a single type dry battery. And the like.

The electrode plate of the present invention can be used as an electrode plate for batteries other than the alkaline secondary battery. Further, the metal porous body of the present invention may be, for example, a carrier for various catalysts, a member for various heating devices (a member for vaporizing or atomizing kerosene, a gas flame plate, etc.) in addition to the electrode plate for the battery. Such as silencers for noise reduction of engines and air equipment, oil mist separators, soot collection members in exhaust gas from diesel engines, electromagnetic wave shielding members, various filters, pistons for diesel engines, etc., and wear-resistant parts for hydraulic equipment, etc. Can be used for various applications.

[0083]

The present invention will be described below based on examples and comparative examples.

Example 1 A sample having a thickness of 1 mm, an average pore diameter of 0.45 mm, and a porosity of 98% was prepared.
A polyurethane foam having a continuous pore structure is used as a core material. First, this core material is treated with a tin chloride aqueous solution at a liquid temperature of 30 ° C. [tin chloride concentration 20 g / liter, concentrated hydrochloric acid concentration 10 m
1 / liter] for 5 minutes to sensitize the surface.

Next, after washing the above core material with water, warm water and deionized water in this order, the following components are added to 1 liter of water, and diluted nitric acid is added to adjust the pH to 9.9.
Immersed in an electroless silver plating bath at a liquid temperature of 35 ° C. for 10 minutes to form a conductive layer having a basis weight of 2 g / m ² ,
After washing with water, a conductive porous body was produced.

(Ingredient) (mmol) * Silver nitrate 8.8 (silver concentration 0.93 g / l) * Ethylenediamine 54 * Rochelle salt 35 * 3,5-Diiodosalicylic acid 0.04 * Glycine 0.04 Manufactured When the conductive porous body was observed using a scanning electron microscope, it was confirmed that a conductive layer composed of an aggregate of silver fine particles was formed on the surface of the core material. The average particle size of the silver fine particles constituting the conductive layer was calculated from an actually measured value from a photograph taken using a scanning electron microscope, and was found to be 0.08 μm. Further, the distribution of the actual particle diameter of the silver fine particles photographed in the above-mentioned photograph is 0.
It was 5 μm or less.

Example 2 An electroless silver plating bath having a solution temperature of 40 ° C. was used, in which the following components were added to 1 liter of water and the pH was adjusted to 10.2 by adding nitric acid and sodium hydroxide. Except that, in the same manner as in Example 1, a conductive porous body having a conductive layer with a basis weight of 5 g / m ² was produced.

(Ingredient) (mmol) * Silver nitrate 8.8 (silver concentration 0.93 g / liter) * Ethylenediamine 54 * Rochelle salt 35 * 3,5-Diiodosalicylic acid 0.04 * Glutamic acid 0.04 When the conductive porous body was observed using a scanning electron microscope, it was confirmed that a conductive layer composed of an aggregate of silver fine particles was formed on the surface of the core material. Further, the average particle size of the silver fine particles constituting the conductive layer was calculated from an actually measured value from a photograph taken using a scanning electron microscope, and was 0.2 μm. The distribution of the actual particle size of the silver fine particles photographed in the above photograph is 0.5%.
μm or less.

Example 3 The same procedure was followed as in Example 1 except that the electroless silver plating bath produced by the following production method was used, and the basis weight was 8 g / g.
A conductive porous body having an m ² conductive layer was produced. The conditions of the electroless silver plating were 1 minute at room temperature. When the manufactured conductive porous body was observed using a scanning electron microscope, it was confirmed that a conductive layer formed of an aggregate of silver fine particles was formed on the surface of the core material. Further, the average particle size of the silver fine particles constituting the conductive layer was calculated from an actually measured value from a photograph taken using a scanning electron microscope, and it was 0.7 μm. The approximate distribution of the actual particle size of the silver fine particles taken in the above photograph is 0.6 to
It was 1.0 μm. Although very small, large-sized silver particles having a particle size of several μm were also confirmed. (Manufacture of electroless silver plating bath) Ammonia water is added dropwise to an aqueous solution of silver nitrate having a concentration of 10 g / liter until the color of the solution turns brown to transparent, and then a mixed aqueous solution of hydrazine sulfate and sodium hydroxide [hydrazine sulfate concentration] 2
0 g / liter and a sodium hydroxide concentration of 5 g / liter] to prepare an electroless silver plating bath.

Comparative Example 1 The same polyurethane foam as used in Example 1 was used as a core material, and this core material was first treated with a 10% aqueous sulfuric acid solution at a rate of 1 g / liter of a surfactant. (Liquid temperature 60 ° C.) for acid cleaning.

Then, after washing the core material with water,
The surface was sensitized by immersing in a palladium chloride-tin chloride mixed aqueous solution at 0.2 ° C. [palladium chloride concentration 0.2 g / l, tin chloride concentration 20 g / l, hydrochloric acid (35% by volume) concentration 200 ml / l] for 1 minute. Processed.

Next, after washing the above-mentioned core material with water, it was immersed for 5 minutes in an electroless nickel plating bath at a liquid temperature of 60 ° C., in which the following components were added to water, to give a conductive weight of 10 g / m ² . A layer was formed and washed with water to produce a conductive porous body.

(Component) (Concentration) * Nickel sulfate 20 g / L * Sodium acetate 5 g / L * Sodium hypophosphite 10 g / L * Sodium citrate 5 g / L * Lactic acid 3 mL / L Manufactured conductive porous material When the body was observed using a scanning electron microscope, it was confirmed that a conductive layer composed of a continuous nickel film was formed on the surface of the core material.

Comparative Example 2 A fine particle of graphite having an average particle diameter of 0.8 μm was added to an alcohol solution in which polyvinyl alcohol and a phenol resin were dissolved at a weight ratio of 7: 3 to an alcohol solution having a concentration of 10 μm.
A coating solution was prepared by dispersing so as to be 0 g / liter.

Next, this coating solution was spray-coated on both sides of the same polyurethane foam used in Example 1 as a core material, and then heated to 100 ° C. and dried to give a basis weight of 20 g / m ^2. Was produced.

When the manufactured conductive porous body was observed using a scanning electron microscope, it was confirmed that a conductive layer composed of an aggregate of graphite fine particles was formed on the surface of the core material. . Further, the average particle size of the graphite fine particles constituting the conductive layer was calculated from an actually measured value from a photograph taken using a scanning electron microscope, and found to be 0.8 μm, which was the same as the graphite fine particles as a raw material. . The actual particle size distribution of the graphite fine particles photographed in the above photograph is 0.1 to
It was 1.5 μm.

The conductive porous bodies produced in the above Examples and Comparative Examples were subjected to the following tests to evaluate the characteristics.

Measurement of Electric Resistance Value I (Initial Value) The conductive porous bodies of Examples and Comparative Examples were 1 cm wide and 1 cm long.
Cut out into a 0cm rectangular shape, and between the both ends in the length direction,
The electric resistance (Ω) in a dry state was measured.

Measurement of Electric Resistance II (After Stretching) The conductive porous body of each of Examples and Comparative Examples was stretched by 10% in one direction and then returned to the original state, so that the stretched direction coincided with the length direction. , 1 cm wide and 10 cm long, and the electrical resistance (Ω) in the dry state between both ends in the length direction was measured.

Measurement of Electric Resistance III (After Bending) Each of the conductive porous bodies of Examples and Comparative Examples was 1 cm wide and 1 cm long.
A 0 cm rectangular shape was cut out, applied to a round bar having a radius of 6 cm, subjected to a 180 ° bending test, returned to its original position, and the electrical resistance value (Ω) between both ends in the length direction in a dry state was measured.

Metal Plating Layer Growth Test The conductive porous body of each of Examples and Comparative Examples was cut out into a rectangular shape having a width of 10 cm and a length of 30 cm.
The conductive porous body was sandwiched between a pair of jigs made of copper over the entire width, and a weight made of polyvinyl chloride was attached to the other end.

Next, the following components were added to 1 liter of water while the conductive porous body was suspended vertically with the weight down so that only the copper jig emerged above the liquid surface. It was immersed in a nickel electroplating bath at a liquid temperature of 45 ° C. <Electroplating bath> (Component) (concentration) * Nickel sulfamate 450 g / liter * Boric acid 30 g / liter Further below the weight of the electroplating bath, platinum is used so as not to contact the conductive porous body. Electrodes were placed.

The copper jig was connected to the cathode of the power supply, and the platinum electrode was connected to the anode of the power supply.
Nickel plating is performed under the condition of 0 A / dm ² , and the growth rate of the nickel plating layer that grows from the surface of the conductive porous body downward from the liquid surface side of the bath, that is, toward the tip end with a weight (c)
m / min) was measured visually.

In the tests, the conductive porous bodies of Examples and Comparative Examples were respectively subjected to the initial state where no deformation was applied (initial state), the state where the above-described stretching was applied (after stretching), and the bending. Each sample in the added state (after bending) was prepared and performed.

Production of Metallic Porous Body and Measurement of Its Electric Resistance Value The above-mentioned growth rate of the nickel plating layer was measured for the conductive porous bodies of Examples and Comparative Examples in an initial state without any deformation. After that, nickel electroplating is further continued under the same conditions to form a nickel plating layer having a basis weight of 600 g / m ^{2 on} the surface of each conductive porous body. 5 minutes, then 900 ° C
The core material was removed by heat treatment in a reducing atmosphere for 30 minutes to produce a porous metal body.

Then, each of the metal porous bodies was 1 cm wide and 1 cm long.
It was cut into a rectangular shape of 0 cm, and the electrical resistance value (Ω) between both ends in the length direction in a dry state was measured.

Tables 1 and 2 show the above results.

[0108]

[Table 1]

[0109]

[Table 2] From both tables, the conductive porous body of Comparative Example 1 in which the surface of the core material was made conductive by a continuous layer of electroless nickel plating, the electric resistance value was significantly increased by stretching and bending. It was found that it broke, and the electric resistance increased to infinity.

In order to produce a porous metal body, nickel electroplating was carried out using the conductive porous body of Comparative Example 1 as a cathode. It was found that the nickel plating layer could not be grown on the sample in which the speed was remarkably reduced, and especially the sample in which the continuous film was broken by stretching and the electric resistance value was increased to infinity.

Further, a porous metal body was manufactured using a sample in an initial state in which the growth rate of the nickel plating layer was relatively high and no deformation was applied. It was found that the resistance value significantly increased.

Further, the conductive porous body of Comparative Example 2 in which the surface of the core material was made conductive by fine particles of carbon inherently has a remarkably high electric resistance value, and in particular, the binder resin is cracked by stretching. It was found that the electric resistance value further increased.

In order to produce a porous metal body, nickel was electroplated using the conductive porous body of Comparative Example 2 as a cathode. From the initial state where no deformation was applied, the plating rate was remarkably increased. In addition to the low, especially the sample whose electric resistance value has increased significantly by stretching as described above,
It was found that the nickel plating layer could not be grown.

When a metal porous body was manufactured using the conductive porous body in the initial state without any deformation, the electric resistance was slightly higher than in each of the examples.

On the other hand, all of the conductive porous bodies of Examples 1 to 3 in which the surface of the core material was made conductive by a conductive layer composed of an aggregate of silver fine particles, the electric resistance value was too small by stretching and bending. Turned out not to rise. In particular,
In the conductive porous bodies of Examples 1 and 2 in which the average particle diameter of the silver fine particles was 0.5 μm or less, the electric resistance value hardly changed even by stretching and bending.

In order to produce a metal porous body, nickel was electroplated using the conductive porous bodies of Examples 1 to 3 as cathodes. In any state after the deformation, the growth rate of the nickel plating layer did not change and was completely the same. In particular, in the conductive porous bodies of Examples 1 and 2, the growth rate of the nickel plating layer itself was also lower than that of Example 3.
Or a higher value than the initial state of Comparative Example 1.

Further, when a metal porous body was manufactured using the conductive porous body in the initial state without deformation, the electric resistance value was remarkably lower than that of Comparative Example 1.

[0118]

As described in detail above, according to the present invention,
With excellent productivity and production efficiency of porous metal body,
A conductive porous body capable of producing a metal porous body having a low electric resistance value, and an electric resistance value which is low due to being produced from such a conductive porous body, for example, when used as an electrode plate for a battery. It has a specific function and effect that it is possible to provide a metal porous body capable of improving charge / discharge efficiency and an electrode plate for a battery formed of such a metal porous body and having excellent charge / discharge efficiency. .

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akiyo Kariya 1-1-1 Kunyokita, Itami-shi, Itami-shi, Hyogo F-term in Sumitomo Electric Industries, Ltd. Itami Works (reference) 5H017 AA02 BB01 BB16 CC28 DD05 DD06 EE01 EE04 HH03

Claims (6)

[Claims] 1. A conductive porous body characterized in that a porous body made of synthetic resin having a continuous pore structure is used as a core material, and a conductive layer made of an aggregate of silver fine particles is formed on the surface thereof. . 2. The conductive porous body according to claim 1, wherein the silver fine particles forming the conductive layer have an average particle size of 0.5 μm or less. 3. A continuous metal plating layer formed on the surface of the conductive porous body by electroplating using the conductive porous body according to claim 1 as a cathode. body. 4. The metal porous body according to claim 3, wherein the metal plating layer is a nickel plating layer. 5. A porous metal body, wherein the porous metal body according to claim 3 is heat-treated to remove a synthetic resin core. 6. An electrode plate for a battery, comprising the metal porous body according to claim 3 or 5 as a main component.