KR101199305B1 - Manufacturing Method of Highly Electro-conductive Carbon Fibers Using Cobalt Based Reducing Agent - Google Patents

Abstract

The present invention relates to a method for producing a highly conductive carbon fiber, and more specifically, to increase the conductivity through the electroless plating surface treatment of nickel, in particular nickel plated to minimize the content of phosphorus (P) using a cobalt-based reducing agent It relates to a carbon fiber and a method for producing the same having better conductivity.
The highly conductive carbon fiber of the present invention has excellent properties such as heat resistance, chemical stability, electrical conductivity, electromagnetic shielding flexibility, and can be used as an internal filler of plastic having high conductivity.

Description

Manufacturing Method of Highly Electro-conductive Carbon Fibers Using Cobalt Based Reducing Agent

The present invention relates to a highly conductive carbon fiber and a method for producing the same.

Recently, almost all devices are equipped with electrical and electronic equipment for the generation, transmission, and storage of information processing, and improve the efficiency as a modern device. However, as the use of such electric and electronic equipment increases, the electromagnetic interference between devices and devices increases, causing even a large social problem such as electromagnetic disturbances in the air, and even causing serious attention to humans. .

In particular, plastics are excellent in formability and low in price, and the demand for housing in various information and communication fields is exploding. However, due to insulation and electromagnetic wave transmission, a high functional electromagnetic shielding effect is required.

Highly conductive carbon fiber has excellent properties such as heat resistance, chemical stability, electrical conductivity, electromagnetic shielding flexibility, and can be used as an internal filler of plastic having high conductivity.

Electroless plating is most often used as a method of manufacturing high-conductivity carbon fibers. In the case of electroless plating, not only has an excellent shielding effect but also has the advantage of forming a plating layer having a constant thickness on the fiber surface.

However, the conventional electroless plating method (Korean Patent No. 486,962) is a metal plating solution in which a metal salt, a reducing agent and a complexing agent coexist, and the carbon fiber is nickel-plated on the surface of the carbon fiber by nickel plating of carbon fiber by chemical reduction. By introducing a, to form a film of a constant thickness, it was a method of improving the conductivity of the carbon fiber, but as the phosphorus content of the alloy increases, the specific resistance increases rather than the problem of reducing the conductivity of the carbon fiber.

In order to solve the above problems, the present inventors have successfully completed the present invention by producing a highly conductive carbon fiber using a cobalt-based reducing agent that does not contain phosphorus. After all, the object of the present invention is to provide a method for producing a highly conductive carbon fiber by using a cobalt-based reducing agent.

In order to achieve the above object, the present invention provides a method for producing a nickel electroless plating high conductive carbon fiber using a cobalt-based reducing agent.

Specifically, the present invention provides a method for producing highly conductive carbon fibers in which nickel is plated on carbon fibers by immersing the carbon fibers in a plating solution containing a nickel salt, a complexing agent, a stabilizer, and a cobalt-based reducing agent.

Nickel electroless plating high conductivity carbon fiber manufacturing method according to the present invention can have a high conductivity by preventing the increase of the specific resistance by the phosphorus (P) component by using a cobalt-based reducing agent. In addition, even if the plating in a short time and low temperature compared to using a conventional reducing agent it is possible to plate a high content of nickel, thereby increasing the efficiency of the plating.

1 is an X-ray diffraction (XRD) analysis result of an electroless nickel plated carbon fiber according to Comparative Example 1.
Figure 2 is an XRD analysis of the electroless nickel plated carbon fiber according to Example 4.
3 is a scanning electron microscope (SEM) analysis result of the electroless nickel plated carbon fiber according to Comparative Example 1.
Figure 4 is a SEM analysis of the electroless nickel plated carbon fiber according to Example 5.

The present invention provides a nickel electroless plating highly conductive carbon fiber using a cobalt-based reducing agent and a method of manufacturing the same.

Specifically, the present invention provides a method for producing highly conductive carbon fibers in which nickel is plated on carbon fibers by immersing the carbon fibers in a plating solution containing a nickel salt, a complexing agent, a stabilizer, and a cobalt-based reducing agent.

In the present invention, to the electroless nickel as a main component a salt of nickel plating solution is preferably from NiSO _4? 6H ₂ O. This is because NiSO ₄ ˜6H ₂ O has a fast plating speed at low temperatures. As the reducing agent, a cobalt (Co) -based reducing agent to which phosphorus is not added is preferable. This is because the cobalt-based reducing agent does not contain phosphorus (P), unlike the conventional reducing agent, and thus has an effect of preventing an increase in specific resistance due to the phosphorus component. Cobalt-based reducing agents specifically CoSO ₄ 7H ₂ O, or cobalt - may be used ethylenediamine (ethylenediamine) complex. Na ₃ C ₆ H ₅ O ₇ can be used as the complexing agent. When Na ₃ C ₆ H ₅ O ₇ is used as the complexing agent, it is possible to inhibit the rapid reduction rate of the salt. In addition, Pb (NO ₃ ) ₂ may be used as a stabilizer. When Pb (NO ₃ ) ₂ is used as a stabilizer, it is effective to prevent decomposition of the bath, to prevent coarse nickel precipitation, and to prevent precipitation of the plating bath.

Moreover, as for the temperature of a plating liquid, 30-90 degreeC is preferable. If it is less than 30 ℃ chemical reduction reaction is difficult to occur, and if it exceeds 90 ℃ may damage the fiber surface and burn the phenomenon of the fiber itself.

In the present invention, the plating liquid immersion time of the carbon fiber is preferably 1 to 30 minutes. Less than 1 minute is not preferable because the amount of nickel film formed on the surface of the fiber is too small because the reaction time of the autocatalytic reaction is too short. If the amount exceeds 30 minutes, the amount of the film rises rapidly, resulting in poor workability.

As described above, the thickness of the nickel plating film and the amount of nickel plating can be adjusted by controlling the plating solution temperature and the plating solution immersion time.

The carbon fiber may be activated with tin chloride (SnCl ₂ ) or palladium chloride (PdCl ₂ ) before immersion in the plating solution. By this process, tin or palladium nuclei are formed on the carbon surface, and these nuclei serve to catalyze metal precipitation.

In the present invention, the thickness of the nickel film plated on the surface of the carbon fiber is preferably 0.08 to 6.0 mu m. If the thickness of the metal film is less than 0.08 μm, it is difficult to measure the electrical conductivity, and there may be a problem that it is difficult to protect the surface of the carbon fiber during plating. When the thickness exceeds 6.0 µm, the metal film becomes excessively thick, which causes loss of excellent properties of the carbon fibers as well as poor workability.

In addition, the nickel content is suitable 5 to 60% by weight. If the content of nickel is less than 5% by weight, there may be a problem that it is difficult to obtain even conductivity of the carbon fiber, and if it exceeds 60% by weight, there may be a problem of losing the properties of the fiber.

In addition, the specific resistance of the electroless plated highly conductive carbon fiber is preferably 1 × 10 ^-3 Ωcm or less. If it exceeds 1 × 10 ^-3 Ωcm, the conductivity is too low to be used as a filling.

Hereinafter, the present invention will be described in more detail with reference to Examples.

However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

Experimental Example  Nickel Electroless  Plated Carbon fiber  Conductivity measurement

In order to measure the electrical conductivity of the nickel electroless plated carbon fiber prepared in the following examples, the specimen after measuring the resistance (V / I) using a 4-probe volum resistivity tester (Mituvishi Chemical Co., MCP-T610) The electrical conductivity σ was calculated using the relationship with the dimension (W × T: cross-sectional area of the fiber side surface; L: distance between voltage contacts).

Experimental Example  2. Nickel Electroless  Plated Carbon fiber  Surface structure, thickness change and characteristic check

Scanning electron microscope (SEM JEOL JSM0840A) and X-ray diffraction analysis were performed to observe the surface structure, thickness change and characteristics of the nickel electroless plated carbon fiber prepared in the following examples. As a generator, Rigaku Model D / MAX-III equipped with CuKα was used.

Example  One. Electroless  Nickel plated Carbon fiber  Manufacture Ⅰ

Carbon fiber used in the present invention is a polyacrylonitrile (PAN) -based high-strength carbon fiber (TC-3K-36) produced by Formosa Platic Co., which is desizing with acetone for 2 hours The fibers were pretreated with 0.1 M nitric acid (HNO ₃ ) for 30 minutes to remove impurities on the surface before metal plating and then used.

Nickel plating of carbon fiber was performed by electroless plating method, activated in tin chloride (SnCl ₂ ) solution for 10 minutes, washed in distilled water, and activated again for 10 minutes using palladium chloride (PdCl ₂ ). Washed.

In addition, NiSO ₄ 6H ₂ O (20 g / L) was used as the electroless plating solution, Na ₃ C ₆ H ₅ O ₇ (27 g / L) as a complexing agent, and Pb (NO ₃ ) ₂ (0.5 ppm) as a stabilizer. Were used respectively. The reducing agent was electroless plated at a temperature of 30 ° C. for 1 minute using a cobalt-ethylenediamine complex compound (27 g / L) and then completely dried in a dryer to prepare nickel plated carbon fibers.

Table 1 below shows the results of plating film thickness, specific resistance, and nickel content of the carbon fiber prepared according to the type, temperature and plating time of the non-phosphoric reducing agent used in the present invention.

Example  2. Electroless  Nickel plated Carbon fiber  Produce II

The same process as in Example 1 was carried out, but electroless plating was performed at a temperature of 60 ° C. for 10 minutes using a cobalt-ethylenediamine complex compound (27 g / L) as a reducing agent.

The plating film thickness, specific resistance, and nickel content of the nickel electroless plated carbon fiber prepared as described above were measured and the results are shown in Table 1 below.

Example  3. Electroless  Nickel plated Carbon fiber  Produce III

The same process as in Example 1 was carried out, but using the cobalt-ethylenediamine complex compound (27 g / L) as a reducing agent was electroless plated at a temperature of 30 ℃ for 20 minutes.

The plating film thickness, specific resistance, and nickel content of the nickel electroless plated carbon fiber prepared as described above were measured and the results are shown in Table 1 below.

Example  4. Electroless  Nickel plated Carbon fiber  Produce IV

The same process as in Example 1 was performed, but the electroless plating was performed at a temperature of 40 ° C. for 25 minutes using a cobalt-ethylenediamine complex compound (27 g / L) as a reducing agent.

The plating film thickness, specific resistance, and nickel content of the nickel electroless plated carbon fiber prepared as described above were measured and the results are shown in Table 1 below.

Example  5. Electroless  Nickel plated Carbon fiber  Produce V

The same process as in Example 1 was carried out, but electroless plating was performed at a temperature of 40 ° C. for 30 minutes using a cobalt-ethylenediamine complex compound (27 g / L) as a reducing agent.

The plating film thickness, specific resistance, and nickel content of the nickel electroless plated carbon fiber prepared as described above were measured and the results are shown in Table 1 below.

Example  6. Electroless  Nickel plated Carbon fiber  Produce VI

The same process as in Example 1 was carried out, but electroless plating was performed at a temperature of 90 ° C. for 10 minutes using a cobalt-ethylenediamine complex compound (27 g / L) as a reducing agent.

The plating film thickness, specific resistance, and nickel content of the nickel electroless plated carbon fiber prepared as described above were measured and the results are shown in Table 1 below.

Comparative example  One.

Perform the same process as in Example 1, using an electroless plating for 30 minutes at a temperature of 50 ℃ using NaH ₂ PO ₂ as a reducing agent, the plating film thickness, specific resistance, Nickel content was measured and the results are shown in Table 1 below.

Comparative example  2.

Performed in the same process as in Example 1, using the NaH ₂ PO ₂ as a reducing agent to perform electroless plating for 30 minutes at a temperature of 80 ℃, in the prepared nickel electroless plating carbon fiber plated film thickness, resistivity, Nickel content was measured and the results are shown in Table 1 below.

division reducing agent time
(minute) Temperature
(℃) Nickel content
(%) thickness
(Μm) Resistivity
(Ωcm) Example 1 Cobalt-Ethylenediamine Complex One 30 5 0.08 9.18 × 10 ^-5 Example 2 10 60 35 1.61 3.37 × 10 ^-5 Example 3 20 30 40 2.21 2.20 × 10 ^-5 Example 4 25 40 45 3.68 1.83 × 10 ^-6 Example 5 30 40 50 3.71 1.82 × 10 ^-6 Example 6 10 90 40 3.55 2.81 × 10 ^-5 Comparative Example 1 NaH ₂ PO ₂ 30 50 3 0.01 0.81 × 10 ^-3 Comparative Example 2 30 80 4 0.07 0.92 × 10 ^-3

Highly conductive carbon fibers prepared as described above can be made of pure nickel on the surface of carbon fiber by using a plating solution using a cobalt-based reducing agent, thereby improving the conductivity compared to nickel-phosphorus (Ni-P) plating, and at the same time, The thickness was uniform and uniform plating was possible.

In addition, when the cobalt-based reducing agent is used as shown in Table 1, it can be seen that the nickel content is increased even when the plating is performed at a low temperature and a short time, compared to Comparative Examples 1 and 2. In addition, when compared with Example 1 and Comparative Example 2 has a similar nickel content ratio and the thickness of the nickel plating, the specific resistance of Example 1 containing less phosphorus is much lower than that of Comparative Example 2 it can be confirmed that the electrical conductivity is increased. there was.

In addition, X-ray diffraction analyzer (XRD) analysis results of the electroless nickel plated carbon fiber according to Comparative Example 1 (Fig. 1) and XRD analysis results of the electroless nickel plated carbon fiber according to Example 4 (Fig. 2) In the case of Comparative Example 1 NiP ₂ peak is observed while in Example 4 it can be seen that only the Ni peak is observed. Comparing the SEM results (FIG. 3) of the scanning electron microscope (SEM) analysis according to Comparative Example 1 and the SEM analysis results (FIG. 4) of the electroless nickel plated carbon fibers according to Example 5, a cobalt-based reducing agent was used in terms of plating thickness. When it is confirmed that there is a difference that a thick nickel film is formed.

Claims (11)

A method for producing a highly conductive carbon fiber having a specific resistance of 1 × 10 ⁻³ Ωcm or less, prepared by plating carbon fiber with nickel by immersing the carbon fiber in a plating solution containing a nickel salt, a complexing agent, a stabilizer, and a cobalt-based reducing agent.
The method of claim 1, wherein the nickel salt is NiSO ₄ 6H ₂ O.
The method of manufacturing a highly conductive carbon fiber according to claim 1, wherein the complexing agent is Na ₃ C ₆ H ₅ O ₇ .
The method of manufacturing a highly conductive carbon fiber according to claim 1, wherein the stabilizer is Pb (NO ₃ ) ₂ .
The method of claim 1, wherein the cobalt-based reducing agent is CoSO ₄ ~ 7H ₂ O or cobalt-ethylenediamine complex method.
The method of manufacturing a highly conductive carbon fiber according to claim 1, wherein the plating solution has a temperature of 30 to 90 ° C.
The method of claim 1, wherein the immersion time is 1 to 30 minutes.
The method of manufacturing a highly conductive carbon fiber according to claim 1, wherein the carbon fiber is activated with tin chloride (SnCl ₂ ) or palladium chloride (PdCl ₂ ) before the carbon fiber is immersed.
The method of manufacturing a highly conductive carbon fiber according to claim 1, wherein nickel is plated on the carbon fiber in a thickness of 0.08 to 6.0 µm.
The method of manufacturing a highly conductive carbon fiber according to claim 1, wherein the nickel content plated on the carbon fiber is 5 to 60 wt%.
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