Plating pretreatment method

Abstract

To provide a plating material that can increase adhesion force of metal plating more than before, and to provide a plating pretreatment method.SOLUTION: A plating fiber 1 includes: a carbon fiber 10; and metal plating 20 for coating the carbon fiber 10, where plating catalyst metal 30 having an average particle diameter of 0.1 nm or more and 30 nm or less is dispersed at a surface of the carbon fiber 10 to be a boundary surface between the carbon fiber 10 and the metal plating 20. A plating pretreatment method includes: an immersion step of loading the carbon fiber 10 into a treatment tank to immerse the carbon fiber into a supercritical fluid including an organometallic complex of the plating catalyst metal 30 or a subcritical fluid; and a decompression step of decompressing the interior of the treatment tank at a speed of 0.05 kg / min or more and 0.2 kg / min or less after immersing the carbon fiber 10 into the fluid in the immersion step.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to Plating pretreatment method .

Background Art

[0002] Conventionally, plating materials obtained by applying metal plating to carbon materials such as carbon fibers have been proposed. Such plating materials can enhance the adhesion of the plating, for example, by roughening the surface of the carbon material by etching to produce an anchor effect. However, although such plating materials can enhance the adhesion of the plating by the anchor effect, the plating adhesion has not yet been sufficient.

[0003] Therefore, a pre-plating treatment method has been proposed in which a supercritical fluid or a subcritical fluid containing an organometallic complex is immersed in carbon fibers that do not contain an oil agent to attach the organometallic complex to the surface of the carbon fibers (for example, Patent Documents 1 and 2). According to this pre-plating treatment method, by attaching an organometallic complex to the surface of the carbon fibers, metal plating can be applied to the carbon fibers with higher adhesion in subsequent electroless plating processes and the like.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] Furthermore, the plating pretreatment method according to the present invention comprises an immersion step of introducing a carbon material into a treatment tank and immersing the carbon material in a supercritical or subcritical fluid containing an organometallic complex of a plating catalyst metal, and a depressurization step of reducing the pressure inside the treatment tank at a rate of 0.05 kg / min or more and 0.2 kg / min or less after immersing the carbon material in the fluid in the immersion step. [Effects of the Invention]

[0009] According to the present invention, the adhesion strength of metal plating can be further improved. Plating pretreatment method We can provide this. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing a plated fiber, which is an example of a plated material according to an embodiment of the present invention. [Figure 2] Figure 1 shows a magnified view of a portion of the plated fiber, where (a) is a photograph taken with a transmission electron microscope (TEM), (b) shows the elemental mapping of the plating catalyst metal at the same location as (a), and (c) shows the elemental mapping of the metal plating at the same location as (a). [Figure 3] This is a process diagram showing the manufacturing method of plated fibers according to this embodiment. [Figure 4] This figure shows TEM images (photographs) and elemental mappings for each process. [Figure 5] This figure shows a 180° bending test of plated fibers according to Example 1 and plated fibers according to Comparative Example 1, where (a) shows the 180° bending test in progress and (b) shows the results of the 180° bending test. [Figure 6]This graph shows the conductor resistance of the plated fiber according to Example 1 and the plated fiber according to Comparative Example 1. [Figure 7] Figure 3 shows a diagram illustrating the state of the plated fibers when the temperature is changed during the thermal reduction process. [Modes for carrying out the invention]

[0011] The present invention will be described below in accordance with preferred embodiments. It should be noted that the present invention is not limited to the embodiments shown below, and can be modified as appropriate without departing from the spirit of the invention. Furthermore, in the embodiments shown below, some illustrations and descriptions of certain components are omitted. It goes without saying that, regarding the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate, to the extent that they do not contradict the content described below.

[0012] Figure 1 is a cross-sectional view showing a plated fiber, which is an example of a plated material according to an embodiment of the present invention. The plated fiber (plated material) 1 shown in Figure 1 comprises a carbon fiber (carbon material) 10 and a metal plating 20 that coats the carbon fiber 10. The carbon fiber 10 is a fiber obtained by carbonizing acrylic fiber or pitch (a by-product of petroleum, coal, coal tar, etc.) at high temperature.

[0013] The metal plating 20 is a conductive metal plating formed on the carbon fiber 10, and is formed, for example, by an electroless plating process utilizing a chemical reaction. This metal plating 20 is composed of one or more metals selected from the group consisting of copper, silver, gold, nickel, chromium, tin, zinc, palladium, rhodium, ruthenium, antimony, bismuth, germanium, cadmium, cobalt, and indium.

[0014] Further, the plating fiber 1 has a plating catalyst metal 30 for depositing the above-described metal plating 20 by a chemical reaction. The plating catalyst metal 30 is a metal composed of at least one selected from gold, platinum, palladium, nickel, silver, copper, iron, titanium, zinc, aluminum, tin, rhodium, ruthenium, antimony, bismuth, germanium, cadmium, cobalt, indium, yttrium, barium, gallium, scandium, zirconium, tantalum, molybdenum, tungsten, manganese, rhenium, osmium, iridium, thallium, rubidium, cesium, vanadium, lead, niobium, and chromium.

[0015] FIG. 2 is a partially enlarged view of the plating fiber 1 shown in FIG. 1. (a) shows a photograph taken by a transmission electron microscope (TEM), (b) shows the state of elemental mapping of the plating catalyst metal 30 at the same location as (a), and (c) shows the elemental mapping of the metal plating 20 at the same location as (a).

[0016] First, as shown in FIG. 2(a), a metal plating 20 is formed on the carbon fiber 10. Referring to FIG. 2(b) while paying attention to the interface (the surface of the carbon fiber 10) between the carbon fiber 10 and the metal plating 20, it can be seen that the plating catalyst metal 30 is dispersed in the portion corresponding to the surface of the carbon fiber 10. The average particle size of this plating catalyst metal 30 is 0.1 nm or more and 30 nm or less.

[0017] Here, when the average particle size of the plating catalyst metal 30 is 30 nm or less, it can be said that the plating catalyst metal 30 is somewhat small. When such a somewhat small plating catalyst metal 30 adheres to the surface of the carbon fiber 10 (the interface between the carbon fiber 10 and the metal plating 20) and the metal plating 20 is deposited, the metal plating 20 will be deposited at a position close to the surface of the carbon fiber 10. As a result, the metal plating 20 will easily adhere to the surface of the carbon fiber 10 and the adhesion strength will be improved.

[0018] Furthermore, in the present embodiment, the average particle size of the plating catalyst metal 30 is 0.1 nm or more. For this reason, it is possible to suppress a situation in which unevenness occurs in the metal plating 20, as in the case where the average particle size is too small when the average particle size is less than 0.1 nm, and the plating catalyst metal 30 cannot be dispersed at a high density on the surface of the carbon fiber 10.

[0019] Also, as shown in FIGS. 2(a) and 2(c), the metal plating 20 is deposited along the nano-order irregularities (depth or height is 5 nm or more and 50 nm or less) of the interface. For this reason, the metal plating 20 is deposited in accordance with the fine irregularities of the carbon fiber 10, and the metal plating 20 that matches the irregularities is obtained, and the adhesion is improved.

[0020] Next, a method for manufacturing the plated fiber 1 according to the present embodiment will be described. FIG. 3 is a process diagram showing a method for manufacturing the plated fiber 1 according to the present embodiment, and FIG. 4 is a diagram showing a TEM image (photograph) and elemental mapping in each process.

[0021] In manufacturing the plated fiber 1 according to the present embodiment, first, a bundle of carbon fibers 10 composed of a plurality of carbon fibers 10 is prepared in a fiber preparation step (FIG. 3: S1). The carbon fiber 10 prepared in the fiber preparation step may contain an oil agent or may not contain an oil agent. In the following description, it is assumed that the carbon fiber 10 contains an oil agent.

[0022] After the fiber preparation step, a pre-plating treatment is performed on the bundle of carbon fibers 10. The pre-plating treatment includes an immersion step (S2), a thermal reduction step (S3), and a depressurization step (S4).

[0023] In the pre-plating treatment, first, an immersion step is performed (S2). In the immersion step, a bundle of carbon fibers 10 is put into a treatment tank (not shown), and the bundle of carbon fibers 10 is immersed in a supercritical fluid or a subcritical fluid containing an organometallic complex of a plating catalyst metal 30 (for example, palladium) (for example, in supercritical carbon dioxide).

[0024] Subsequently, a depressurization process is performed (S3). In the depressurization process, the pressure inside the treatment tank is reduced at a rate of 0.05 kg / min to 0.2 kg / min. The depressurization rate can be adjusted by the opening of a valve and the diameter of a flow path provided on the flow path for releasing the fluid inside the treatment tank into the atmosphere. In the manufacturing method of the plated fiber 1 according to this embodiment, the average particle size of the plating catalyst metal 30 is optimized (to 30 nm or less) by setting the depressurization rate to 0.05 kg / min or more. When an organometallic complex dissolved in a supercritical or subcritical fluid is released into the atmosphere, the pressure and temperature of the fluid drop rapidly, and the dissolving power of the fluid drops rapidly. If this rapid drop in dissolving power occurs in a short time, the degree of saturation in the fluid also drops rapidly, and only a small amount is dissolved before release, resulting in the deposition of the plating catalyst metal 30 as fine particles. Therefore, increasing the depressurization rate makes the plating catalyst metal 30 finer (smaller). In addition, setting the depressurization rate to 0.2 kg / min or less prevents the equipment requirements from becoming excessively high. Furthermore, after the reduced pressure process, the plating catalyst metal 30 (organometallic complex) is located at a point slightly away from the surface of the carbon fiber 10, as shown in Figure 4, due to the influence of the surface lubricant.

[0025] Next, a thermal reduction process is performed as shown in Figure 3 (S4). In the thermal reduction process, the temperature inside the treatment tank is raised to 250°C or higher. As a result, even if the carbon fibers 10 contain an oil, the oil will volatilize. Also, because the oil volatilizes, each of the multiple carbon fibers 10 becomes open (the fibers are not stuck together). It is preferable that the heating state is continued for 30 minutes or more (preferably 1 hour or more). Furthermore, as shown in Figure 4, after the thermal reduction process, because the oil volatilizes, the plating catalyst metal 30 is not located at a distance of the oil thickness from the surface of the carbon fibers 10, but is attached to the surface of the carbon fibers 10. In particular, even if the surface of the carbon fibers 10 has nano-order irregularities, the plating catalyst metal 30 will adhere along these irregularities.

[0026] After the completion of the above-described pre-plating treatment, an electroless plating process is performed (S5). This applies a metallic plating 20 to the carbon fibers 10. In this process, some of the plating catalyst metal 30 that was attached to the surface of the carbon fibers 10 detaches from the surface as the plating is deposited. As a result, as shown in Figure 4, after the electroless plating process, the plating catalyst metal 30 is dispersed in the metallic plating 20.

[0027] Next, the examples and comparative examples will be described. Figure 5 shows a 180° bending test of plated fibers according to Example 1 and plated fibers according to Comparative Example 1, where (a) shows the 180° bending test and (b) shows the results of the 180° bending test. For the 180° bending test, as shown in Figure 5(a), a 200g weight W was suspended from one end (lower end) of the plated fiber, and the upper part of the plated fiber (slightly lower than the upper end) was sandwiched between a pair of φ2mm mandrels M. Next, the other end (upper end) of the plated fiber was repeatedly bent along the mandrel M so that the bending angle was 180°. The number of bends at which the conductor resistance value increased by 10% due to repeated bending was measured.

[0028] For the plated fibers in Example 1, fibers with various average particle sizes within the range of 0.1 nm to 30 nm were used (the depressurization rate was adjusted so that the average particle sizes were 0.1 nm, 10 nm, 20 nm, and 30 nm, respectively). Figure 5 shows the minimum number of bends for each. On the other hand, for the plated fibers in Comparative Example 1, fibers with an average particle size exceeding 30 nm were used (more specifically, fibers with an average particle size of approximately 110 nm or less, and which were electroless plated). Figure 5 shows the average value of the number of bends measured multiple times. In Example 1 and Comparative Example 1, the organometallic complex was palladium, and the metal plating was copper.

[0029] As a result of the 180° bending test described above, the plated fiber according to Example 1 underwent 10,600 bending cycles, while the plated fiber according to Comparative Example 1 underwent 7,050 bending cycles.

[0030] Thus, it was found that the plated fibers according to Example 1 are more resistant to repeated bending and less prone to peeling of the metal plating than the plated fibers according to Comparative Example 1, meaning they have higher adhesion.

[0031] Figure 6 is a graph showing the conductor resistance of the plated fiber according to Example 1 and the plated fiber according to Comparative Example 1. The graph in Figure 6 was obtained by measuring the resistance value while moving the other end of a plated fiber that has a length of 140m or more, with one end set to 0m. In Figure 6, the resistance values ​​for Example 1 and Comparative Example 1 are shown as average values.

[0032] As shown in Figure 6, the plated fiber according to Example 1 exhibits a stable resistance value at all points in its length from 0m to 140m. On the other hand, the plated fiber according to Comparative Example 1 shows spikes in resistance at lengths exceeding 50m, slightly less than 70m, approximately 90m, and slightly less than 120m. In other words, it was found that the plating deposition was stable for the plated fiber according to Example 1, while it was unstable and uneven for the plated fiber according to Comparative Example 1.

[0033] Figure 7 is a diagram showing the state of the plated fibers when the temperature is changed in the thermal reduction process shown in Figure 3. Note that in the plated fibers of Examples 2 and 3 and Comparative Examples 2 and 3 shown in Figure 7, the organometallic complex is palladium and the metal plating is copper.

[0034] As shown in Comparative Example 2 in Figure 7, when the temperature inside the treatment tank was raised to 130°C (1 hour), some oil remained. As a result, the fibers remained stuck together, and metal plating was deposited only around the fiber bundles (i.e., metal plating was not deposited between the fibers). As shown in Comparative Example 3, the same result was obtained when the temperature inside the treatment tank was raised to 200°C (1 hour) during the heat reduction process.

[0035] In contrast, as shown in Example 2, when the temperature inside the treatment tank was raised to 250°C (1 hour), no oil residue remained. As a result, the fibers did not stick together and remained in an open state, allowing the metal plating to precipitate even between the fibers. Similarly, as shown in Example 3, when the temperature inside the treatment tank was raised to 300°C (1 hour) during the heat reduction process, the same result was obtained.

[0036] In this way, according to the plated fiber 1 of this embodiment, a plating catalyst metal 30 with an average particle size of 0.1 nm to 30 nm is dispersed on the surface of the carbon fiber 10. Since the average particle size of the plating catalyst metal 30 is 30 nm or less, even if the metal plating 20 is deposited at the position furthest from the interface among the plating catalyst metals 30, the plating catalyst metals 30 themselves are small, so the metal plating 20 is deposited at a position relatively close to the interface, thereby increasing the adhesion strength of the metal plating 20.

[0037] Furthermore, since the average particle size of the plating catalyst metal 30 is 0.1 nm or more, it is possible to suppress situations where the average particle size becomes too small, as in the case where the average particle size is less than 0.1 nm, and unevenness occurs in the metal plating 20 unless the plating catalyst metal 30 is dispersed at high density on the surface of the carbon fiber 10.

[0038] Furthermore, since the metal plating 20 is deposited along the surface irregularities of the carbon fiber 10, the metal plating 20 is deposited in accordance with the fine irregularities of the carbon fiber 10, further enhancing adhesion.

[0039] Furthermore, according to the pre-plating treatment method of this embodiment, the pressure inside the treatment tank is reduced at a rate of 0.05 kg / min to 0.2 kg / min after the immersion step, which leads to the plating catalyst metal 30 adhering to the carbon fiber 10 such that the average particle size is 0.1 nm to 30 nm. Therefore, the adhesion strength of the metal plating 20 can be further enhanced.

[0040] Furthermore, by raising the temperature inside the treatment tank to over 250°C, the organometallic complex is activated while simultaneously removing any oil, even if the carbon fiber 10 contains oil. Therefore, the degree of freedom in selecting the carbon fiber 10 can be improved.

[0041] Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments, and modifications may be made or well-known technologies may be combined without departing from the spirit of the present invention.

[0042] For example, in the above embodiment, a plated fiber 1 in which a metal plating 20 is applied to a carbon fiber 10 was described, but the material to which the metal plating 20 is applied is not limited to carbon fiber 10, but may be other carbon materials.

[0043] Furthermore, in the above embodiment, the metal plating 20 is deposited along the surface irregularities of the carbon fiber 10. However, it is not necessary for the metal plating 20 to be deposited along all irregularities. For example, if the metal plating 20 is deposited along 80% or more of the irregularities with a depth or height of 3 nm to 50 nm, it can be said that the metal plating 20 is deposited along the surface irregularities of the carbon fiber 10.

[0044] Furthermore, in the plating pretreatment method according to the above embodiment, the thermal reduction step is not limited to 250°C and 300°C, but may also be exposed to higher temperatures or longer periods of time, as long as it does not damage the carbon fibers 10.

[0045] Furthermore, the depressurization rate may be adjusted so that the average particle size of the plating catalyst metal 30 is smaller than the average height of the surface irregularities of the carbon fiber 10.

[0046] In addition, in this embodiment, the plated fiber 1 has the plating catalyst metal 30 attached to the surface of the carbon fiber 10 by volatilizing the oil at a high temperature of 250°C or higher. However, this is not limited to this method, and any method that can attach the plating catalyst metal 30 to the surface of the carbon fiber 10, such as removing the oil by washing, is acceptable, and the material is not limited to one manufactured through a process that exposes it to a high temperature of 250°C or higher. [Explanation of symbols]

[0047] 1: Plated fiber (plated material) 10: Carbon fiber (carbon material) 20: Metal plating 30: Catalyst metal for plating

Claims

1. The process involves introducing a carbon material into a processing tank and immersing the carbon material in a supercritical or subcritical fluid containing an organometallic complex of a plating catalyst metal, and After immersing the carbon material in the fluid in the immersion step, a depressurization step is performed in which the inside of the treatment tank is depressurized at a rate of 0.05 kg / min or more and 0.2 kg / min or less. A method for pre-treatment before plating, characterized by comprising the following:

2. A thermal reduction process is performed after the depressurization step, in which the temperature inside the treatment tank is raised to 250°C or higher. The pre-plating treatment method according to claim 1, further comprising the features described above.

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