JPH0120263B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Background and Objectives of the Invention The present invention relates to an electroplating method for carbon fiber bundles.

Carbon fiber has a high modulus of elasticity and an extremely small coefficient of thermal expansion, so it is attracting attention as a special material. Furthermore, since it itself has relatively high conductivity, it can also be subjected to electrical treatments such as electroplating, and has the potential for an even wider range of applications. Conventionally, it has been thought that carbon fibers could be electroplated and knitted into a conductive fabric-like material that could be used as a material for various electrical devices, but it has been thought that carbon fibers can be electroplated and woven into conductive fabric-like materials that can be used as materials for various electrical devices. It is inefficient and uneconomical to apply electroplating to the carbon fibers as they are, so it was considered to handle the carbon fibers in bundles and apply metal plating uniformly to each fiber. When metal plating such a carbon fiber bundle, an important problem is how to spread the fiber bundle in which the single fibers are in a bundled state and apply metal plating to each single fiber to a uniform thickness. There are two methods for opening the carbon fiber bundles: when plating the carbon fiber bundle with metal, hydrogen gas is generated as a cathode reaction, and this is used to spread the fibers, and a jet of plating liquid is applied to the fiber bundle from a direction perpendicular to the fiber bundle. Although several proposals have been made, none of them yielded satisfactory results, such as insufficient opening or breakage of single fibers. On the other hand, the carbon fiber bundle is run in a plating bath, and plating liquid jet nozzles are arranged on both sides of the running fiber bundle, and the plating liquid is spouted in the running direction of the fiber bundle. The fiber opening method causes very little breakage of single fibers, and opens the fibers well.

On the other hand, although carbon fiber bundles are conductive, they have a fairly high electrical resistance, so it is not possible to pass a high-density current through a carbon fiber bundle, and if a large current is forced to flow through the carbon fiber bundle, it will generate heat and burn out. Put it away. Therefore, when increasing the plating thickness or increasing the plating speed, a multi-stage plating method using a plurality of plating baths is essential. However, in this multi-stage plating method, the fiber opening state in the second and subsequent plating tanks is 1.
There was a problem that the plating thickness was worse than that of the tank, and the plating thickness eventually became uneven.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to provide a method for sufficiently opening a fiber bundle even in a multi-stage plating method, and stably plating each single fiber with metal to a uniform thickness. be.

(2) Summary of the Invention The present invention provides a method for electroplating the surface of each single fiber of a carbon fiber bundle little by little by sequentially passing through a plurality of plating tanks each filled with a plating solution. In order to open the carbon fiber bundles in the plating tank, a plating liquid is spouted along the running path of the carbon fiber bundle in each of the plating tanks to form a spouted flow of the plating liquid along the running path. In the second and subsequent plating baths, the non-spreading portions of the carbon fiber bundles are further electrically shielded so that only the spread portions of the carbon fiber bundles are electroplated. be.

First, an example of an embodiment of the electroplating method of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram showing the first tank and the second tank in the apparatus according to the embodiment of the example as a sectional side view, and FIG. 2 is a process diagram showing the process diagram of FIG. 1 as a top sectional view. It is a diagram. The third and subsequent tanks in the apparatus are similar to the second tank, but are not shown in the drawings. Since FIG. 1 and FIG. 2 show the same apparatus, both figures will be described together. In both figures and in each tank, 1 is a carbon fiber bundle, 2 is a metal plating tank, 3 is a metal plating bath liquid, 4 is a jetting mechanism for the metal plating bath liquid, 5 is a rectifying plate for the jetting bath liquid, 6 is an anode plate, 7 is a cathode column, 8 is a recovery tank for metal plating bath liquid, 9 is a jetting pump, and 10 is a current shielding member. As shown in the figure, the first tank 2 includes a fiber bundle 1
In a bathtub having an inlet hole and an outlet hole, when the fiber bundle 1 is passed through both holes, the metal plating liquid 3 will be filled even if some liquid leaks from the gap between the fiber bundle 1 and each hole. It's getting wet. Further, the amount of liquid 3 reduced due to liquid leakage is supplied by a spouting mechanism 4 for metal plating liquid 3, which will be described later. When the amount of metal plating liquid 3 supplied by the spouting mechanism 4 becomes excessive, the excess is made to flow out through an overflow hole (not shown) and is collected in a bath liquid recovery tank. In the first tank 2, a spouting mechanism for metal plating liquid is arranged along the traveling path of the fiber bundle 1 on both sides or around it, and in front of the spouting mechanism, there is also a jetting mechanism along the traveling path of the fiber bundle 1. In order to prevent the ejected liquid flow from spreading as much as possible and to make the ejected liquid flow reach a further distance, rectifying plates 5 are installed facing each other. A board 6 is embedded. The opposing rectifying plates 5 are spaced apart from each other to an extent that does not hinder the opening of the fiber bundle 1, as will be described later. Thereafter, the running path of the fiber bundle 1 continues to the delivery hole. A cathode column 7 is installed outside the tank on the delivery hole side, and the fiber bundle 1 to be sent out is placed on the cathode column 7.
It is designed to run while touching the tank and enter the next tank.

When applying metal plating to the carbon fiber bundle 1, the fiber bundle 1 is introduced into the apparatus from the left side of the figure. The fiber bundle 1 enters the tank through the introduction hole of the plating tank 2, passes between a pair of jetting mechanisms as shown in the drawings and described above, and then travels between each pair of current plate 5 and anode plate 6. do. The plating tank 2 is filled with bath liquid 3, and when electricity is applied between an anode plate 6 in the tank and a cathode column 7 (described later), the potential of the cathode column 7 is changed by the running fiber bundle 1. As a result, electricity is eventually applied between the anode 6 and the fiber bundle 1 (via the plating bath liquid), and the components of the bath liquid 3 are deposited on the fiber bundle 1, forming a plating layer. be. On the other hand, the bath liquid 3 is ejected from the jetting mechanism 4 along the running direction of the fiber bundle 1.
is powerfully ejected, and the ejected flow flows through the above-mentioned rectifier plate 5.
The fiber bundle 1 running in a violent flow inside the enclosure is violently vibrated, and the vibration causes the fiber bundle 1 to
As shown in the diagram, the fibers open and become a single fiber. This single fiber is plated with metal. As described above, the fiber bundle 1 is then re-bundled from the spread state, passes through the delivery hole, comes into contact with the cathode column 7, and then exits the first tank.

The fiber bundle 1 then enters the introduction hole of the second tank. Second
The basic difference from the first tank is that the fiber bundle 1 that enters the second tank from the introduction hole is metal-plated by the current shielding member 10 until it is opened again by the jetting mechanism 4. The current from the bath liquid 3 is not received. This point is the most distinctive feature of the present invention. When attempting to continuously plate a fiber bundle by passing it through a plating tank, it is ideal to spread the fiber bundle from the entrance to the exit of the plating tank, that is, over the entire length. It is difficult to realize this. Therefore, normally the fibers are opened only partially, but the plating progresses even in the non-spreading area, which makes it even more difficult to open the plated non-spreading area, and the plating thickness also varies from the spread state. This leaves the problem that there is a significant difference between the plated part and the plated part when the fibers are not spread. Therefore, it is extremely important to prevent the fiber bundle from plating when it is not spread. The second illustrated
In the layer a current shielding element 10 is arranged and the introduced fiber bundle 1 passes through the through hole of the element 10 into the jet stream. The fiber bundle 1 passing through the through hole of the member 10 does not come into contact with enough plating liquid to be plated, and its surface is hardly or not plated at all. Therefore, when the fiber bundle 1 enters the ejected liquid stream, it is sufficiently opened and the fibers are uniformly plated. Thereafter, in the same manner as in the case of the first tank, the fiber bundle 1
leaves the second tank and heads to the third tank. 2nd tank after 3rd tank
Similar to the bath, a current shielding member is provided, and the fiber bundle 1 is not plated while the current is passing through the member.

The reason why the current shielding member was installed after the second tank is because the electric resistance of the fiber bundle is quite high in the first tank, so the mesh layer is formed after the ejection hole of the jetting mechanism, and there is no current shielding member. The non-spreading part is not plated, and on the other hand, from the second tank onward, the first
Since the plating layer is plated to some extent in the bath, current flows through this plating layer, lowering the overall electrical resistance, and as a result, not only the spread part but also the non-spread part is plated.

The carbon fiber bundle 1 in the present invention is a bundle of conventionally known carbon fibers, and in the method of the present invention, the bundle is passed through a metal plating bath as it is, and each single fiber is uniformly plated. . Metal plating solutions are conventionally known, and their main metals include copper, silver, gold, tin, chromium, lead-tin, nickel-tin, copper-tin, iron, and zinc. The jetting mechanism consists of a plating liquid jetting power and a jetting nozzle.
The ejecting power is a so-called pump, and the plating liquid forcefully pushed out by the pump is further ejected from an ejection nozzle with a narrowed inner hole to make the plating liquid in the tank into a strong liquid flow. The jetting mechanism is arranged to generate a jetting liquid flow along the traveling direction of the traveling fiber bundle. Only one unit may be placed on one side, but preferably several units may be placed on both sides of the fiber bundle to stabilize the running of the fiber bundle, or in a ring shape centered on the running position of the fiber bundle. .
The rectifier plate 5 is a separator plate that secures a liquid path, and is arranged to allow the liquid flow to reach a long distance without being spread too much. In the case of a plate-shaped rectifying plate disposed opposite to each other on both sides of the running position, it is more preferable that the current plate has an annular shape centered on the running position of the fiber bundle. This is because the annular shape prevents the liquid flow from dispersing upward and downward.

When the fiber bundle travels through the current plate, the fibers are opened due to the turbulence of the ejected liquid flow, and an anode plate is placed inside or behind the current plate so that electroplating occurs at this time. The form and arrangement of the anode plate are arbitrary. Depending on its shape and placement, the anode plate can also function as a rectifier plate.
The cathode column placed outside the tank comes into contact with the fiber bundle coming out of the plating tank and functions as a cathode. Although the figure shows a case where columnar objects are arranged facing each other, the shape does not necessarily have to be columnar, and may be plate-like or arranged on only one side.

The current shielding member, which is the most characteristic feature of the present invention, may be tubular as shown, or may have other shapes. Of course, it is made of an electrically insulating material, and the electricity that is applied to the plating solution bath does not pass inside.

The plating solution slightly leaking from the inlet or outlet hole of each tank and the plating solution overflowing into the bathtub is collected into the tank via a pipe or groove. The plating solution in the recovery tank may be supplied to the jetting mechanism as shown, or it may be supplied to the bath solely for replenishment of the plating solution. A pump 9 is provided for replenishing them. In the figure, the pipe from the pump 9 is shown as being connected to the jetting mechanism 4, but it does not necessarily need to be connected to the jetting mechanism 4 depending on the purpose of supplying the plating liquid from the pipe.

(3) Example The present invention was carried out using the apparatus shown in FIGS. 1 and 2. 3000 carbon fibers with a diameter of 7μ
This was bundled and supplied to the first tank. A copper plating solution is used as the metal plating bath solution, and a current of 5 to 10 V and 5 to 20 V is passed to the first tank, and a current of 5 to 20 V and 10 to 50 A is passed to the second tank, and the carbon fiber is heated. The traveling speed of the bundle was approximately 0.3-1 m/min.

In this example, both the first tank and the second tank were in a good opening state, and copper plating with a substantially uniform thickness was applied.

(4) Effects of the Invention According to the present invention, the introduced fiber bundle can be sufficiently opened in a multistage electroplating tank, and for this purpose, a metal plating layer is uniformly and rapidly formed on the surface of each single fiber. can be formed, so it is possible to efficiently produce metal-plated fibers of excellent quality. Furthermore, the apparatus implementing the present invention has an economical advantage in that it is only necessary to install members of extremely simple structure.

[Brief explanation of drawings]

FIG. 1 is a process diagram including a cross section of the first tank and the second tank of the electroplating bath according to an embodiment of the present invention as seen from the side, and FIG. 2 is a process diagram including a cross section of each tank in FIG. 1 as seen from the top surface. It is a diagram. DESCRIPTION OF SYMBOLS 1... Carbon fiber bundle, 2... Metal plating tank, 3... Metal plating bath liquid, 4... Metal plating bath liquid jetting mechanism, 5
. . . Current plate for spouting bath liquid, 6. Anode plate, 7. Cathode column, 8. Metal-plated bath liquid recovery tank, 9. Spout pump, 10. Current shielding member.

Claims (1)

[Claims] 1. In a method of electroplating the surface of each single fiber of a carbon fiber bundle little by little by sequentially passing through a plurality of plating tanks each filled with a plating solution, the carbon fiber bundle traveling in each of the plating tanks is opened. forming a spouted liquid flow of the plating liquid along the running path of the carbon fiber bundle by spouting the plating liquid along the running path of the carbon fiber bundle in each of the plating tanks,
A method for electroplating a carbon fiber bundle, characterized in that in the second and subsequent plating tanks, only the spread part of the carbon fiber bundle is electroplated by electrically shielding the non-spread part of the carbon fiber bundle. .