KR20110132894A - Manufacturing method of highly electro-conductive carbon fibers using boron based reducing agent - Google Patents

Abstract

PURPOSE: A manufacturing method of highly electro-conductive carbon fibers using boron based reducing agent is provided to increase conductivity, by preventing the rising of resistivity due to phosphorus components. CONSTITUTION: A manufacturing method of highly electro-conductive carbon fibers using boron based reducing agent comprises a step of plating nickel to carbon fiber by using plating liquid consisting of nickel salt, complex agent, stabilizer, and boron-based reducing agent. The nickel salt is NiSO46H2O or NiCl2·6H2O. The complex agent is NaC6H5O7. The stabilizer is Pb(NO3)2. The boron-based reducing agent is Sodium Boro Hydride, NaBH4, (CH3)2NHBH3 and the mixture thereof.

Description

Manufacturing Method of Highly Electro-Conductive Carbon Fibers Using Boron Based Reducing Agent

The present invention relates to a highly conductive carbon fiber and a method for manufacturing the same, and more specifically, to increase conductivity through electroless plating surface treatment of nickel, in particular, the content of phosphorus (P) by using a boron-based reducing agent as a reducing agent in the plating solution. The present invention relates to a carbon fiber having a superior conductivity by plating nickel with a minimized amount, and a method of manufacturing 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 the devices and devices increases, causing a great social problem such as electromagnetic disturbances, and even a serious hazard to the human body, which has been attracting high attention. .

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. In order to form a film having a constant thickness to improve the conductivity of the carbon fiber, but as the phosphorus content in the alloy increases, the specific resistance increases rather than the problem of reducing the conductivity of the carbon fiber.

Accordingly, the present inventors, in order to solve the above problems, by using a plating solution using a boron-based reducing agent, by performing a surface treatment through electroless plating, by forming a pure nickel film on the surface of the carbon fiber to produce a highly conductive carbon fiber The present invention has been successfully completed.

After all, an object of the present invention is to provide a method for producing a highly conductive carbon fiber using a boron-based reducing agent.

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

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

In the present invention, the nickel salt as the main component of the electroless nickel plating solution is preferably NiSO ₄ · 6H ₂ O or NiCl ₂ · 6H ₂ O. Specifically, as the boron-based reducing agent, sodium borohydride (NaBH ₄ ), dimethylamine borane ((CH ₃ ) ₂ NHBH ₃ ), or a mixture thereof may be used. Sodium citrate (NaCHO) may be used as the complexing agent. In addition, Pb (NO ₃ ) ₂ may be used as a stabilizer.

Nickel plating is performed on the surface of the carbon fiber through the electroless plating proposed in the present invention, and Ni-B alloy is introduced on the surface of the carbon fiber to form a film having a predetermined thickness, thereby producing a highly conductive carbon fiber.

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 boron-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 a SEM measurement result of the electroless nickel plated carbon fiber according to Example 1.
2 is a SEM measurement result of the electroless nickel plated carbon fiber according to Comparative Example 1.

The present invention provides a nickel electroless plating highly conductive carbon fiber using a boron-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 using a plating solution containing a nickel salt, a complexing agent, a stabilizer, and a boron-based reducing agent.

In the present invention, NiSO ₄ .6H ₂ O or NiCl ₂ .6H ₂ O is preferable as the nickel salt. More preferably, it is preferable to select NiSO ₄ · 6H ₂ O, because the plating speed has an effect. The reducing agent is preferably a boron-based reducing agent. This is because, unlike the conventional reducing agent, since phosphorus (P) is not included, there is an effect of preventing the increase in specific resistance due to the phosphorus component. Specifically, the boron-based reducing agent may be sodium borohydride, dimethylamine borane or a mixture thereof. Sodium citrate (NaCHO) may be used as the complexing agent. When sodium citrate is used as the complexing agent, the rate of salt reduction can be suppressed. In addition, Pb (NO ₃ ) ₂ may be used as a stabilizer. This is because the use of Pb (NO ₃ ) ₂ as a stabilizer has the effect of preventing decomposition of the bath, preventing coarse nickel precipitation, and preventing precipitation of the plating bath.

In addition, the temperature of the plating liquid is preferably 20 ~ 100 ℃. If it is less than 20 ℃ chemical reduction reaction is difficult to occur, and if it exceeds 100 ℃ the fiber surface is damaged and the fiber itself burns out. More preferably, when using dimethylamine borane as a reducing agent, 25 ~ 65 ℃ is preferred, when using sodium borohydride 40 ~ 100 ℃ is preferred.

In addition, the plating liquid can be used in the range of pH 3 ~ 17. If the pH is less than 3, there may be a problem that the quality of the plating layer is deteriorated. If the pH is higher than 17, the plating solution may cause self-decomposition and may not be smoothly plated. More preferably, when using dimethylamine borane as a reducing agent, pH 6 ~ 8.5 is preferred, and when using sodium borohydride as a reducing agent, pH 12 ~ 14 is preferred.

In the present invention, the plating bath exposure time of the carbon fiber is preferably 1 to 60 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 self-catalytic reaction time is too short, and if the amount exceeds 60 minutes, the amount of the film rises rapidly, which is not suitable.

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 is less than 0.08 μm, the metal film is too thin to make it difficult to measure the electrical conductivity, and a problem arises that it is difficult to protect the carbon fiber surface 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 based on the total carbon fiber. If the content of nickel is less than 5% by weight, not only is it difficult to obtain even conductivity of the carbon fiber, but if it is more than 60% by weight, the fiber properties are not suitable.

In addition, the boron content of the plated fiber surface is preferably 0.3 to 10% by weight based on the total carbon fiber. If it is out of the range there may be a problem that the life of the plating liquid is lowered. More preferably, when using dimethylamine borane as the reducing agent is preferably 0.3 to 3% by weight, and when using sodium borohydride as the reducing agent is preferably 5 to 7% by weight.

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

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 merely to illustrate the present invention, but the content of the present invention is not limited by the following examples.

Experimental Example  1: 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

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, the electroless plating solution was used NiSO ₄ 6H ₂ O (20 g / L) and NaC ₆ H ₅ O ₇ as a complexing agent Pb (NO ₃ ) ₂ (0.5 ppm) was used as a stabilizer (27 g / L), respectively. The reducing agent was added sodium carbon borohydride (21 g / L) to a nickel electroless plating solution of pH 6 and electroless plated at a temperature of 30 ° C. for 1 minute, followed by complete drying in a dryer. Carbon fiber was prepared.

Table 1 below shows the results of plating film thickness, electrical conductivity, and nickel content of the carbon fibers prepared according to the type, temperature, and plating time of the boron-based reducing agent used in the present invention.

Example  2

The same process as in Example 1 was performed, but electroless plating was performed at a temperature of 65 ° C. for 1 minute.

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

Example  3

The same process as in Example 1 was performed, but the carbon fibers were placed in a nickel electroless plating solution having a pH of 7.5 and electroless plated at a temperature of 65 ° C. for 10 minutes.

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

Example  4

The same process as in Example 1 was performed, but the carbon fibers were placed in a nickel electroless plating solution having a pH of 7.5 and electroless plated at a temperature of 40 ° C. for 25 minutes.

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

Example  5

The same process as in Example 1 was performed, but the carbon fibers were placed in a nickel electroless plating solution having a pH of 8.5 and electroless plated at a temperature of 40 ° C. for 10 minutes.

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

Example  6

The same process as in Example 1 was performed, but the carbon fiber was placed in a nickel electroless plating solution having a pH of 8.5 and electroless plated at a temperature of 25 ° C. for 10 minutes.

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

Example  7

The same process as in Example 1 was performed, but the carbon fibers were placed in a nickel electroless plating solution having a pH of 17 and electroless plated at a temperature of 100 ° C. for 60 minutes.

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

Example  8

The same process as in Example 1 was performed, but the carbon fiber was placed in a nickel electroless plating solution having a pH of 3 and electroless plated at a temperature of 10 ° C. for 30 seconds.

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

Example  9

The same process as in Example 1 was performed, but the reducing agent was added to the carbon fiber in a nickel electroless plating solution having a pH of 12 using dimethylamine borane (24.3 g / L) and electroless plating at a temperature of 60 ° C. for 30 minutes. It was.

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

Example  10

The same process as in Example 1 was performed, but the reducing agent was added to the carbon fiber in a nickel electroless plating solution having a pH of 12 using dimethylamine borane (24.3 g / L) and electroless plating at a temperature of 60 ° C. for 5 minutes. It was.

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

Example  11

The same process as in Example 1 was carried out, but the reducing agent was added to the carbon fiber in a nickel electroless plating solution of pH 13 using dimethylamine borane (24.3 g / L) and electroless plating at a temperature of 90 ° C. for 20 minutes. It was.

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

Example  12

The same process as in Example 1 was performed, but the reducing agent was added to the carbon fiber in a nickel electroless plating solution having a pH of 13 using dimethylamine borane (24.3 g / L) and electroless plating at a temperature of 40 ° C. for 20 minutes. It was.

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

Example  13

Performing the same process as in Example 1, the reducing agent was added to the carbon fiber in a nickel electroless plating solution of pH 14 using dimethylamine borane (24.3 g / L) electroless plating at a temperature of 60 ℃ for 1 minute It was.

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

Example  14

The same process as in Example 1 was carried out, but the reducing agent was added to the carbon fiber in a nickel electroless plating solution having a pH of 14 using dimethylamine borane (24.3 g / L) and electroless plating at a temperature of 90 ° C. for 30 minutes. It was.

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

Example  15

The same process as in Example 1 was performed, but the reducing agent was added to the carbon fiber in a nickel electroless plating solution having a pH of 17 using dimethylamine borane (24.3 g / L) and electroless plating at a temperature of 100 ° C. for 60 minutes. It was.

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

Example  16

The same process as in Example 1 was performed, but the reducing agent was added to the carbon fiber in a nickel electroless plating solution of pH 3 using dimethylamine borane (24.3 g / L) and electroless plating at a temperature of 10 ° C. for 30 seconds. It was.

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

Comparative example  One

Perform the same process as in Example 1, using the NaH ₂ PO ₂ as a reducing agent for 30 minutes at an temperature of 50 ℃ electroless plating, the thickness of the plated film, electrical conductivity in the prepared electroless nickel plated carbon fiber , The nickel content was measured and the results are shown in Table 1 below.

Comparative example  2

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

division reducing agent time
(minute) Temperature
(℃) Boron content
(%) pH thickness
(Μm) Resistivity
(Ωcm) Example 1 Sodium borohydride One 25 0.3 6 0.68 5.85 × 10 ^-4 Example 2 One 65 0.3 6 0.81 5.14 × 10 ^-4 Example 3 10 65 1.5 7.5 2.74 4.16 × 10 ^-5 Example 4 30 65 1.5 7.5 4.82 4.71 × 10 ^-6 Example 5 10 40 3 8.5 2.83 4.08 × 10 ^-5 Example 6 10 25 3 8.5 2.28 6.14 × 10 ^-5 Example 7 60 100 10 17 6.81 1.56 × 10 ^-7 Example 8 0.5 10 0.1 3 - 3.89 × 10 ^-3 Example 9 Dimethylamine Borane 30 60 5 12 4.91 3.16 × 10 ^-6 Example 10 5 60 5 12 2.62 5.89 × 10 ^-5 Example 11 20 90 6 13 4.23 1.18 × 10 ^-5 Example 12 20 40 6 13 4.08 2.15 × 10 ^-5 Example 13 One 60 7 14 0.91 4.56 × 10 ^-4 Example 14 30 90 7 14 5.13 0.89 × 10 ^-6 Example 15 60 100 10 17 7.18 1.27 × 10 ^-7 Example 16 0.5 10 0.1 3 - 3.89 × 10 ^-3 Comparative Example 1 NaH ₂ PO ₂ 30 50 - 6 0.01 0.81 × 10 ^-3 Comparative Example 2 30 80 - 6 0.07 0.92 × 10 ^-3

The highly conductive carbon fibers prepared as described above have a higher conductivity than the nickel-phosphorus (Ni-P) plating by introducing Ni-P into the carbon fiber surface by using a plating solution using a boron-based reducing agent, and at the same time, the fiber surface shape. The thickness of was uniform and uniform plating was possible.

In addition, as shown in Table 1, when the boron-based reducing agent is used it can be seen that the electrical resistance is significantly lower compared to Comparative Examples 1 and 2.

In addition, when comparing the electron scanning microscope (SEM) measurement results (SEM) of the electroless nickel plated carbon fiber according to Example 1 (Fig. 1) and SEM measurement results (Fig. 2) of the electroless nickel plated carbon fiber according to Comparative Example 1 In terms of the thickness of nickel plated on the surface of the carbon fiber, it was confirmed that a thicker nickel film was formed using the boron-based reducing agent.

Claims (12)

A method for producing a highly conductive carbon fiber in which nickel is plated on a carbon fiber using a plating solution containing a nickel salt, a complexing agent, a stabilizer, and a boron-based reducing agent.
The method of claim 1, wherein the nickel salt is NiSO ₄ 6H ₂ O or NiCl ₂ · 6H ₂ O.
The method of producing a highly conductive carbon fiber according to claim 1, wherein the complexing agent is NaC 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 boron-based reducing agent is sodium boro hydride (Sodium Boro Hydride, NaBH ₄ ), dimethylamine borane ((CH ₃ ) ₂ NHBH ₃ ) or a mixture of high carbon fiber, characterized in that Way.
The method of claim 1, wherein the temperature of the plating liquid is 20 ~ 100 ℃.
The method of claim 1, wherein the plating time is 1 to 60 minutes.
The method of claim 1, wherein the plating solution is pH 3 ~ 17.
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 claim 1, wherein the nickel content to be plated on the carbon fiber is 5 to 60% by weight.
The method of manufacturing a highly conductive carbon fiber according to claim 1, wherein the boron content to be plated on the carbon fiber is 0.3 to 10% by weight.
The method of claim 1, wherein the carbon fiber is activated with tin chloride (SnCl ₂ ) or palladium chloride (PdCl ₂ ) before plating the carbon fiber.

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