JPH0651167B2 - Method for producing metal porous body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a metal porous body having a three-dimensional network structure, which imparts conductivity to a synthetic resin having a three-dimensional network structure as a pretreatment for metal plating. It concerns the improvement of the method.

Prior Art To manufacture a porous metal body having a three-dimensional network structure,
A synthetic resin having a three-dimensional network structure skeleton (a foam having a three-dimensional network structure and having air permeability, hereinafter simply referred to as a synthetic resin) is manufactured, and a metal is plated thereon. It may be used in the state of being metal-plated, that is, as a metal porous body having a skeleton structure of synthetic resin. However,
Generally, the plated porous body is heated or the synthetic resin portion is removed by another method to use as a porous body made of only metal.

As the plating method, there are (1) a method of directly metal-plating a synthetic resin only by chemical plating, and (2) a method of electroplating a metal with the synthetic resin as a cathode after imparting conductivity to the synthetic resin. .

The method of direct chemical plating on synthetic resin (1) has a slow plating speed, requires the use of a precious metal such as palladium as a catalyst, is expensive, and has a porous structure, so that defoaming or waste liquid during chemical plating is required. Due to processing problems, productivity is extremely poor and it is not suitable for mass production. Therefore, the electroplating method (2) is adopted for mass production.

In this electroplating method, conductivity must first be imparted to the synthetic resin. For this purpose, there are (a) a method in which a thin metal is chemically plated on the synthetic resin as a base, and (b) a method in which a conductive substance such as carbon is applied to the surface of the synthetic resin. Of these, the method using chemical plating is generally used, but the chemical plating method has the above-mentioned drawbacks.
In some cases, a method of coating the synthetic resin skeleton with a conductive material such as carbon powder by an appropriate method is performed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention relates to an improvement in a method of applying electrical conductivity by coating a synthetic resin with carbon powder when producing a porous metal body having a three-dimensional network structure.

Conventionally, to impart conductivity to a synthetic resin by this method, the synthetic resin is immersed in a liquid in which carbon powder is dispersed in a suitable liquid together with a binder and a dispersant, and the synthetic resin is taken out and dried. . However, this method has a drawback in that it takes a long time to dry, and in particular, a solvent containing a binder and a dispersant causes clogging between the skeletons during drying, which seriously hinders electroplating in the next step.

Such a defect is caused by, for example, the pore diameter of the synthetic resin having a three-dimensional network structure, that is, the distance between the skeletons of the network structure, for example,
It becomes remarkable as it becomes a synthetic resin with fine pores of 500 μm or less.

In order to solve such a problem in the production of the porous metal body by electroplating, the applicant of the present invention has proposed a novel method for imparting conductivity to the subject in Japanese Patent Application No. 60-64879.
However, even in the method described in Japanese Patent Application No. 60-64879, no specific processing conditions are specified, and the holes of the synthetic resin network structure are clogged, or the coated carbon layer is used as a substrate. There is still the problem that the carbon layer itself is lifted from the synthetic resin or cracks are generated in the carbon layer itself.

Therefore, the object of the present invention is to solve these problems and to obtain a carbon layer which is free from clogging of the skeleton of the network structure and adheres to the synthetic resin and which is smooth, and the metal plating in the next step is the skeleton of the network structure. It is an object of the present invention to provide a method for forming a layer of a conductive material which is uniformly applied to the entire surface.

Means for Solving the Problems In order to achieve the above object, the present inventor conducted various experiments and studies on a method of forming a conductive material on the surface of a porous synthetic resin, and after infiltrating the conductive paint suspension, By rolling the porous synthetic resin of (1) by roll compression, the film of the conductive paint suspension stretched in the network structure of the synthetic resin can be destroyed, and by further adjusting the suspension conditions of the conductive paint suspension, etc. The inventors have found that the problems can be solved and completed the present invention.

That is, according to the present invention, a synthetic resin having a three-dimensional network structure is soaked in a conductive paint suspension, excess conductive paint suspension is removed from the synthetic resin, and dried to obtain a surface of the synthetic resin. A method for producing a metal porous body, which comprises the steps of forming a conductive layer and then subjecting the synthetic resin to metal plating by electroplating, the method comprising carbon particles having a particle size of 250 to 500 mesh and 20 ° C to 40 ° C. The conductive resin suspension maintained at a temperature in the range of ° C is infiltrated with the synthetic resin, and then the synthetic resin is compressed in a wet state within an elastic limit by a roll to remove excess conductive paint suspension. There is provided a method for producing a porous metal body, which comprises removing and destroying a film of the conductive paint suspension that extends over the network structure of the synthetic resin.

It is preferable that the step of infiltrating the above-mentioned synthetic resin into the conductive paint suspension and the step of removing the excess suspension by roll compression are repeated a plurality of times, and these steps are a tank for containing the conductive paint suspension. It can also be done in-house.

According to a preferred embodiment of the present invention, the conductive paint suspension comprises
It contains water as a dispersion medium and acrylic styrene-based synthetic resin as a binder.

Further according to a preferred embodiment of the present invention, it is preferable to dry the synthetic resin moistened with the conductive paint suspension in an atmosphere in the range of 40 ° C to 80 ° C.

Here, the mesh means a Tyler mesh.

Action As described above, in the method for producing a porous metal body of the present invention, the particle size of the suspension of the conductive paint is reduced when forming the layer of the conductive paint.
It is characterized in that it mainly contains carbon particles of 250 to 500 mesh and is maintained at a temperature in the range of 20 to 40 ° C.

The reasons for limiting the conditions of the method for producing a porous metal body of the present invention will be described below.

Regarding the particle size of carbon particles, the particle size of the sponge-like synthetic resin having a three-dimensional network structure is
For example, in the case of fine pores of 500 μm or less, if the particle size of the conductive coating carbon exceeds 250 mesh, the pores of the resin are likely to be clogged and the product metal porous body is three-dimensional. The features of the network are lost. Further, if the particle size of the carbon particles is less than 500 mesh, it becomes difficult to secure the conductivity required for electroplating. For this reason, it is necessary to limit carbon mainly to particles having a particle size in the range of 250 to 500 mesh.

Temperature of suspension of conductive paint The suspension of conductive paint consists of carbon particles, binder, dispersant and dispersion medium. Must be maintained. When the temperature of the suspension is lower than 20 ° C., the uniform suspension state collapses, and only the binder concentrates on the surface of the skeleton forming the network structure of the synthetic resin to form a layer. Therefore, the layer of carbon particles applied thereon is easily peeled off, and it is not possible to form the metal plating firmly adhered thereto. On the other hand, when the temperature of the suspension exceeds 40 ° C., the amount of evaporation of the dispersion medium is large, the suspension is concentrated with the lapse of the coating treatment time, and the coating amount of carbon fluctuates. Therefore, the temperature of the suspension should be kept in the range of 20 ° C to 40 ° C.

Drying temperature When drying the applied conductive paint, if it is dried in an atmosphere exceeding 80 ° C, the thermal expansion coefficient of carbon and the binder will be different and cracks will tend to occur in the coating layer. It is not possible to obtain a coating layer having uniform conductivity, and it is not possible to achieve uniform metal plating in the next step. On the other hand, drying in an atmosphere of less than 40 ° C takes time and is inefficient. Therefore, it is preferable to dry at a temperature in the range of 40 ° C to 80 ° C.

Hereinafter, the present invention will be described by way of examples with reference to the accompanying drawings. These examples are merely illustrative of the present invention,
Of course, this does not limit the scope of the present invention.

Examples FIG. 1 is a schematic diagram of an apparatus used to carry out the step of wetting a synthetic resin into a suspension of a conductive coating material according to the present invention and compressing and removing excess suspension by rolling. .

As shown, a belt-shaped synthetic resin 1 having a three-dimensional network structure 1
Is wound around the supply bobbin 2, and the resin 1 is unwound from the bobbin 2 and guided through the guide roller 3 into the tank 5 containing the suspension 4 of the conductive paint. The suspension of the conductive paint contains carbon particles in the dispersion medium, a binder and a dispersant, and is kept at a temperature in the range of 20 ° C to 40 ° C. The carbon particles have a particle size in the range of 250 to 500 mesh.

A deflector roll 6 is arranged in the tank 5, and a pair of squeezing rolls 7 and 7 ′ is arranged above the deflector roll 6 and above the suspension surface. Therefore, the strip-shaped synthetic resin 1 infiltrated into the suspension
Is deflected vertically by the deflector roll 6 and the excess suspension is squeezed out by the squeezing rolls 7 and 7 '.

A deflector roll 8 and a winding bobbin 9 are provided outside the tank 5.
The deflector roll 8 and the winding bobbin 9 are provided with a hot air nozzle group 10. In this way, the running direction of the belt-shaped synthetic resin 1 is changed to the direction of the winding bobbin 9 by the deflector roll 8 and dried by the hot air nozzle group 10, and then the winding bobbin 9 is wound.
To be wound up. Here, the temperature of the hot air jetted from the hot air nozzle group 10 is preferably in the range of 40 ° C to 80 ° C.

As described above, when the apparatus shown in FIG. 1 is used, the steps of wetting the synthetic resin into the suspension of the conductive coating material, removing the excess suspension, and drying in the method for producing a porous metal body of the present invention can be performed. It can be done automatically. Further, by complying with the various processing conditions according to the present invention described above, it is possible to form a uniform conductive layer having a stitch structure without clogging and to smoothly perform metal plating in the next step.

FIG. 2 is a schematic diagram of an apparatus for practicing another aspect of the present invention. In FIG. 2, members corresponding to those of the apparatus shown in FIG. 1 are designated by the same reference numerals, and the supply bobbin 2, the winding bobbin 9, and the hot air nozzle group 10 are omitted.

The apparatus shown in FIG. 2 is composed of an elongated tank 5 for containing a suspension 4 of a conductive paint, and inside the tank 5, there is a front portion (corresponding to an inlet side portion of the belt-shaped synthetic resin 1) and a rear portion. Deflector rolls 3 and 3'are respectively arranged at the portions (corresponding to the outlet side of the strip-shaped synthetic resin 1). Between the deflector rolls 3 and 3 ', three pairs of squeezing rolls 7 and 7'are arranged. Therefore, the strip-shaped synthetic resin 1 introduced into the suspension 4 of the conductive paint in the tank 5 is infiltrated into the suspension and the deflector roll 3 can change the traveling direction horizontally, so that the squeeze at the leading position is reduced. The excess suspension is squeezed out by rolls 7, 7 ', leaving these squeeze rolls 7, 7'as the suspension re-infiltrates into the synthetic resin and then the squeeze rolls 7, 7'in the next position Excess suspension is squeezed out with. These are repeated until the squeeze rolls 7 and 7'in the final position are exited.

A deflector roll 3'is arranged on the downstream side of the final position of the squeezing rolls 7 and 7 ', a pair of squeezing rolls 7 and 7'is arranged above it, and a deflector roll 8 is arranged above it. Therefore, the strip-shaped synthetic resin 1 exiting the squeezing rolls 7 and 7'at the last position in the tank is infiltrated by the suspension liquid 4 and runs vertically by the deflector roll 3 ',
Excess suspension is removed by squeezing rolls 7, 7 ',
Next, the traveling direction is changed by the deflector roll 8, and drying and winding are performed by a hot air nozzle and a winding bobbin (not shown).

Next, using the apparatus shown in FIG. 1, the conductivity imparting treatment of the polyurethane foam was performed. The polyurethane foam used was a sponge having a three-dimensional network structure with a pore size of about 500 μm, and had a strip shape with a thickness of 1.8 mm. On the other hand, the suspension of the conductive paint is composed of carbon particles having an average particle size of 10 μm dispersed in water together with a suitable binder and dispersant, and the suspension temperature in the tank is (30 ± 5) ° C. Held in. Further, it was dried using hot air at (60 ± 10) ° C.

The band-shaped synthetic resin after coating was not clogged, and the inside of the network structure was covered with a carbon layer having a uniform thickness and no cracks.

As described above, the present invention has succeeded in forming a conductive layer with high quality and high efficiency on a synthetic resin having a three-dimensional network structure as a base for metal plating. In particular, in the method of the present invention, it is possible to effectively destroy the film of the conductive paint stretched in the network structure of the synthetic resin by roll compression, and the sponge-like synthetic resin is not clogged with the pores and is further applied. Since the carbon layer is formed in close contact with the synthetic resin, there is no risk of peeling. Further, since the carbon particles and the binder are uniformly dispersed and held in the suspension, the carbon particles on the surface of the synthetic resin also form a uniform layer, and cracks do not occur.

Therefore, a conductive layer suitable for metal plating in the next step is formed, and a high quality metal porous body can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view of one embodiment of an apparatus used for forming a conductive layer on a belt-shaped synthetic resin according to the method of the present invention, and FIG. 2 is a schematic view of an apparatus used for forming a conductive layer on a belt-shaped synthetic resin according to the method of the present invention. FIG. 7 is a schematic view of yet another embodiment of an apparatus used to form a permeable layer. (Main reference numbers) 1 ... Band-shaped synthetic resin, 2 ... Supply bobbin, 3,3 ', 6,8 ... Deflector roll, 4 ... Suspension of conductive paint, 7,7' ... Squeeze roll, 9 ... Winding bobbin, 10 ... Hot air nozzle group,

Claims (5)

[Claims] 1. A synthetic resin having a three-dimensional network structure is infiltrated into a conductive paint suspension to remove excess conductive paint suspension from the synthetic resin and dried to make the surface of the synthetic resin conductive. A method for producing a porous metal body, comprising the steps of forming a layer of, and then subjecting the synthetic resin to metal plating by electroplating, the method comprising carbon particles having a particle size of 250 to 500 mesh and a temperature of 20 ° C to 40 ° C. The conductive resin suspension maintained at a temperature in the range is infiltrated with the synthetic resin, and then the synthetic resin is compressed in a wet state by a roll within elastic limits to remove excess conductive paint suspension. A method for producing a porous metal body, which comprises destroying a film of the conductive coating material suspension extending in a network structure of the synthetic resin. 2. The method for producing a porous metal body according to claim 1, wherein the wet synthetic resin is dried at a temperature in the range of 40 ° C. to 80 ° C. 3. The method according to claim 1, wherein the step of infiltrating the conductive resin suspension of the synthetic resin and the step of roll compression are repeated a plurality of times. The method for producing a porous metal body according to. 4. The step of infiltrating the conductive resin suspension of the synthetic resin and the roll compression step is repeated a plurality of times in a tank containing the conductive coating suspension. 4. The method for producing a porous metal body according to any one of items 1 to 3. 5. The conductive paint suspension according to claim 1, wherein water is used as a dispersion medium and acrylic styrene synthetic resin is used as a binder. 2. The method for producing a metal porous body according to item 1.