KR20190024275A - Manufacturing method of conductive carbon papers/epoxy composites using electroless nickel-plating - Google Patents

Abstract

The present invention relates to a method to manufacture a carbon paper/epoxy electromagnetic shielding material, which comprises: (a) a step of immersing pitch-based carbon fiber in a metal plating solution to plate the carbon fiber; (b) a step of mixing an organic polymer compound with the plated carbon fiber via a wet method to make a carbon fiber web; (c) a step of immersing the made carbon fiber web in a thermosetting resin; and (d) a step of hardening the immersed carbon fiber web. According to the present invention, nickel induces reflection and absorption of electromagnetic energy on the pitch-based carbon fiber formed through electroless plating to provide an excellent electromagnetic shield ratio, thereby providing effects of realizing high economic efficiency, a lightweight shape, and a small thickness compared to an existing epoxy composite material, while being applicable to various fields, such as an electronic device, a communication device, a precise device, a smart industry, and the like.

Description

Technical Field [0001] The present invention relates to a method of manufacturing a carbon paper / epoxy electromagnetic shielding material by nickel electroless plating,

The present invention relates to a method of manufacturing a carbon paper / epoxy electromagnetic shielding material by nickel electroless plating, and more particularly, to a method of manufacturing a carbon fiber web by mixing pitch organic carbon fibers by electroless plating and wet- And a method of producing an electromagnetic wave shielding material by impregnating a carbon fiber web with a thermosetting resin and curing the same.

As the use of electronic devices, aviation, electric vehicles, smart communication devices, and precision instrument products are rapidly increasing, electromagnetic waves generated from these products adversely affect the human body, causing various diseases such as neuralgia, headache, dizziness, I have to. In addition, since electromagnetic waves induce malfunctions not only of the human body but also of the devices operating at a specific frequency, they cause unexpected accidents and situations. Therefore, the danger of such electromagnetic disturbances is attracting attention and many studies on electromagnetic shielding Are being actively promoted both domestically and internationally.

In order to shield electromagnetic waves, there has been a method of improving the material of the product itself. Metal materials have been attracting attention as an electromagnetic wave shielding material. Recently, however, methods using light weight, have.

However, since polymeric materials themselves do not have electromagnetic shielding effect, the development of resin-based composite materials capable of absorbing electromagnetic waves while having conductivity by coating a transition metal to a polymer material in order to impart a shielding effect to such materials It is a trend.

An object of the present invention is to provide a method for producing a carbon paper / epoxy shielding material having an excellent electromagnetic wave shielding ratio by impregnating an epoxy resin with a carbon paper prepared by surface-treating pitch-based carbon fibers through electroless plating and in the form of a web have.

According to an aspect of the present invention, there is provided a method of manufacturing a carbon fiber composite material, comprising the steps of: (a) dipping a pitch-based carbon fiber into a metal plating solution; (b) preparing a carbon fiber web by mixing the plated carbon fibers with an organic polymer compound by a wet process; (c) impregnating the carbon fiber web with the thermosetting resin; And (d) curing the impregnated carbon fiber web.

According to an embodiment of the present invention, the plating temperature in step (a) is 30 to 90 ° C.

According to another embodiment of the present invention, in the step (b), the organic polymer compound is polyvinyl alcohol.

According to another embodiment of the present invention, the concentration of the organic polymer compound in the step (b) is 1 to 20 weight ratio to the pitch-based carbon fiber.

According to another embodiment of the present invention, in the step (c), the thermosetting resin is any one selected from the group consisting of phenol resin, urea resin, melamine resin, epoxy resin and unsaturated polyester resin .

As described above, according to the present invention, nickel metal on the surface of pitch-based carbon fiber formed by electroless plating induces reflection and absorption of electromagnetic energy and has an excellent shielding ratio of electromagnetic wave, so that it is more economical than conventional epoxy composite material, And can be applied to a variety of fields such as electronic devices, communication devices, precision instruments, and smart industries, and electromagnetic wave shielding materials using polymer composite resins can be produced only by injection molding of a composite resin, It is effective in terms of productivity.

Fig. 1 shows SEM results of the pitch-based carbon fibers produced in the present invention.
FIG. 2 shows the results of analyzing the electromagnetic wave shielding characteristics of the carbon paper / epoxy electromagnetic wave shielding material produced in the present invention.

Hereinafter, the present invention will be described in detail.

In order to achieve the above object, the present invention provides a carbon paper / epoxy shielding material having excellent electromagnetic shielding ratio, comprising: (a) a step of dipping a pitch-based carbon fiber into a metal plating solution to coat carbon fiber; (b) preparing a carbon fiber web by mixing the plated carbon fibers with an organic polymer compound by a wet process; (c) impregnating the carbon fiber web with the thermosetting resin; And (d) curing the impregnated carbon fiber web.

In the step (a), the plating temperature is preferably 30 to 90 ° C. If the temperature is lower than 30 ° C, the chemical reduction reaction is difficult to occur. If the temperature is higher than 90 ° C, the fiber surface is damaged due to the high temperature, and the fiber itself is burned to deteriorate the physical properties.

The pitch-based carbon fiber may be one prepared by using a petroleum-based, coal-based, mesophase pitch or a mixture thereof as a pitch precursor. The pitch-based carbon fiber is immersed in the metal plating solution to activate the surface within the above temperature range, and the surface is electroless-plated with nickel.

The immersion time of the carbon fiber in the metal plating solution is preferably from 1 minute to 30 minutes. If the immersion time is less than 1 minute, the autocatalytic reaction time is too short, so that the amount of the nickel coating formed on the surface of the fiber is too small, and if it exceeds 30 minutes, the amount of the coating rapidly increases and the workability becomes poor.

As a main component of the nickel salt of the metal plating solution is preferably in a NiCl ₂ 6H ₂ O and NiSO ₄ 6H ₂ O. This is because the plating rate is fast at low temperatures. The complexing agent and stabilizer are preferably Na ₃ C ₆ H ₅ O ₇ 1.5H ₂ O and PdNO ₃ . This can be used to inhibit the rapid rate of salt reduction and to prevent the decomposition of the nucleus and the aggregation phenomenon.

In the step (b) of preparing the carbon fiber web by mixing the organic polymer compound with the plated carbon fiber by a wet process, the organic polymer compound is preferably an acrylic or vinyl resin, more preferably polyvinyl alcohol. Since the organic polymeric compound acts as a binder for binding nickel-plated carbon fibers as a water-soluble polymer, the carbon paper web is prepared by mixing the plated carbon fiber and the organic polymer compound, and ultrasonic dispersion and hot pressing.

The concentration of the organic polymer compound is preferably 1 to 20 wt.%, More preferably 10 to 20 wt.%, Relative to the pitch-based carbon fiber. When the concentration of the organic polymer compound is less than 1 wt.% With respect to the pitch-based carbon fiber, the concentration of the organic polymer is low, which lowers the bonding force between the fibers during the production of the carbon fiber web. If the concentration exceeds 20 wt.%, The cohesion phenomenon is induced and the binding force is lowered. This is because the organic polymer compound is mixed with an aqueous solution and ground by a wet method to prepare a carbon fiber web so that the carbon fiber is placed long side-by-side so that the problems such as breakage of carbon short fibers can be prevented in advance. The wet method has the effect of increasing the strength of the carbon fiber web by orienting the carbon fibers in a two-dimensional plane because the carbon fibers are dispersed and dispersed in the liquid medium and are nervous.

It is preferable to impregnate the plated pitch-based carbon fibers with an organic polymer compound solution in which an aqueous solution, an acrylic resin, a vinyl resin, and a dispersant are mixed and ultrasonically disperse for 1 to 60 minutes. In case of less than 1 minute, the dispersion is not effectively performed and the aggregation phenomenon is induced to lower the physical properties of the web, and the effect is insignificant at 60 minutes or longer, which is not preferable. The dispersing agent may be any one selected from the group including triton X-100, sodium dodecyl sulfate (SDS), Span 80, Tween 85 and Tween 60.

After dispersing ultrasonic waves, the carbon paper web is manufactured by high-temperature bonding at a temperature of 80 to 200 ° C at a pressure of 3 to 10 MPa in a hot pressing process using a hot press. In the case of less than 3 MPa at 80 ° C, the polymer material is excessively retained in the fiber due to the low temperature and pressure, causing the aggregation phenomenon. When the temperature is higher than 200 MPa and 10 MPa or more, Which is undesirable because no binding occurs.

The carbon fiber web is impregnated with a thermosetting resin in step (c) and dried with hot air. The thermosetting resin is preferably at least one selected from the group consisting of phenol resin, urea resin, melamine resin, epoxy resin and unsaturated polyester resin.

The carbon fiber web impregnated with the thermosetting resin is preferably subjected to hot air drying for 12 to 24 hours. When the drying time is less than 12 hours, the solvent is not completely evaporated, and when the drying time is longer than 24 hours, the cured product is exposed to a high temperature for a long period of time to cause deterioration of the fiber properties.

The carbon fiber web impregnated in the step (d) is cured by applying heat and pressure. It is preferable that the carbon fiber web is cured by hot pressing at a temperature of 130 to 210 ° C and a pressure of 3 MPa. When the curing temperature is 130 ° C or lower, complete curing is not induced due to a low temperature. If the curing temperature is 210 ° C or higher, the fiber surface is exposed at a high temperature to cause deterioration of physical properties. When the pressure is 3 MPa or less, the resin remains excessively in the fiber and can not be uniformly cured, thereby causing deterioration of physical properties. When the pressure is 3 MPa or more, the resin escapes and the bonding strength of the carbon fiber is lowered.

The SEM analysis results of the electromagnetic wave shielding material produced by the above method can be seen in FIG. 1, which shows that nickel is introduced on the surface of pitch-based carbon fiber through nickel plating.

FIG. 2 shows the results of analyzing the electromagnetic wave shielding characteristics of the carbon paper / epoxy electromagnetic wave shielding material produced in the present invention. The nickel - plated carbon fiber was combined with the polymer resin to increase the electrical conductivity, increase the surface reflection, and increase the electromagnetic wave absorption with the high permeability filler to produce the electromagnetic shielding material with high efficiency. Comparative Example 2, which was an epoxy resin which was not subjected to any treatment, and Comparative Example 2 which was a carbon paper / epoxy electromagnetic wave shielding material produced by using the unpatched pitch-based carbon fiber, As a result of analyzing each electromagnetic wave shielding characteristic, it can be seen that the shielding effect of Example 7 is more than twice as compared with the comparative examples. This is a result of increasing the bonding force between the pitch carbon fibers through nickel plating and increasing the conductivity by providing metallic property and inducing surface reflection of electromagnetic waves by lowering the impedance, thereby increasing the electromagnetic wave shielding efficiency.

Table 1 shows the production conditions of the conductive carbon paper according to the present invention.

Table 2 shows the electrical conductivity of the conductive carbon paper according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these examples are for illustrative purposes only and that the scope of the present invention is not construed as being limited by these examples.

Measurement example  1. Scanning electron microscope ( SEM )

The shape of the pitch-based carbon fibers prepared in the present invention was observed through FE-Scannig Electron Microscopy (S-4300SE, Hitach Co.).

Measurement example  2. Measurement of Electromagnetic Shielding Characteristics

The shielding properties of the carbon paper / epoxy electromagnetic shielding material prepared in the present invention were observed through an electromagnetic wave shielding meter (AGILENT, USA) according to ASTM D4935-59.

Measurement example  3. Electrical Conductivity Measurement

The electrical conductivity of the carbon paper / epoxy electromagnetic shielding material prepared according to the present invention was measured through a four-probe point method with resistivity tester (MCP-T610, Mitsubishi Chemical Analytech Co., Ltd.).

Example  One.

The pitch-based carbon fiber is activated by supporting it in a 0.1 M SnCl ₂ solution and a 0.0014 M PdCl ₂ solution, and then immersed in a nickel plating solution at 30 ° C for 1 minute to plasto carbon fibers. A mixed aqueous solution was prepared by adding a dispersant and 1 wt.% Of PVA to 100 parts by weight of distilled water, and the plated carbon fibers were added thereto and uniformly ultrasonically dispersed for 1 minute. The dispersed carbon fibers were ground in a square mold and hot-pressed at 80 DEG C and 3 MPa for 2 hours to produce a carbon paper web. 50 wt.% Of an epoxy resin is added to 100 parts by weight of carbon fiber in an organic solvent to prepare a mixed solution. The resin solution prepared above is impregnated with a carbon fiber web and the solvent is removed in a drying oven for 12 hours. Finally, a carbon paper / epoxy electromagnetic wave shielding material was prepared by curing at 130 ° C for 2 hours under a pressure of 3 MPa using a hot press.

Example  2.

The procedure of Example 1 was repeated except that the carbon fibers were immersed in the plating solution for 3 minutes in the plating process, and 5 wt.% Of PVA was added thereto to prepare a mixed aqueous solution. Paper / epoxy electromagnetic shielding materials.

Example  3.

The same procedure as in Example 2 was performed, except that the carbon fiber was immersed in the plating solution for 5 minutes in the plating process, and the carbon paper / epoxy electromagnetic wave shielding material was prepared by curing the resin at 150 ° C. after impregnation.

Example  4.

In the same manner as in Example 3, carbon fibers were immersed in a plating solution at 60 ° C for 8 minutes in the plating process. 10 wt.% Of PVA was added to prepare a mixed aqueous solution, the carbon fibers were ultrasonically dispersed for 10 minutes, and a web was prepared at a temperature of 130 ° C. and a pressure of 6 MPa. After the resin impregnation, / Epoxy electromagnetic shielding materials.

Example  5.

The same procedure as in Example 4 was performed, except that the carbon fiber was immersed in the plating solution for 10 minutes in the plating process. The resin was impregnated and cured at 170 캜 to prepare a carbon paper / epoxy electromagnetic wave shielding material.

Example  6.

The same procedure as in Example 5 was carried out except that the carbon fiber was immersed in the plating solution for 15 minutes in the plating process. The carbon fiber was ultrasonically dispersed for 30 minutes, and a web was produced at a temperature of 180 ° C to prepare a carbon paper / epoxy electromagnetic wave shielding material.

Example  7.

The same procedure as in Example 6 was performed, except that the carbon fiber was immersed in a plating solution at 90 캜 for 20 minutes in the plating process. The mixed aqueous solution was prepared by adding 15 wt.% Of PVA, hot air dried for 24 hours after resin impregnation, and cured at 190 ° C to prepare a carbon paper / epoxy electromagnetic shielding material.

Example  8.

The same procedure as in Example 7 was carried out except that the carbon fiber was immersed in the plating solution for 25 minutes in the plating process. The carbon fiber was ultrasonically dispersed for 60 minutes, and a web was manufactured under a pressure of 10 MPa to prepare a carbon paper / epoxy electromagnetic shielding material.

Example  9.

The same procedure as in Example 8 was performed, except that the carbon fiber was immersed in the plating solution for 30 minutes in the plating process. A mixed aqueous solution was prepared by adding 20 wt.% Of PVA, and a web was prepared at a temperature of 200 ° C., and the resin was impregnated and cured at 210 ° C. to prepare a carbon paper / epoxy electromagnetic shielding material.

Comparative Example  One.

The epoxy resin used in the examples

Comparative Example  2.

A carbon paper / epoxy electromagnetic wave shielding material was prepared using the same procedure as in Example 7, except that the pitch-based carbon fiber was not plated.

Plating liquid temperature
(° C) Immersion time
(minute) abandonment
Polymer
(wt.%) Ultrasonic dispersion
(minute) carbon
Fiber web
Temperature
(° C) carbon
Fiber web
pressure
(MPa) sirocco
dry
(h) Hardening
Temperature
(° C) Example 1 30 One One One 80 3 12 130 Example 2 30 3 5 5 80 3 12 130 Example 3 30 5 5 5 80 3 12 150 Example 4 60 8 10 10 130 6 18 150 Example 5 60 10 10 10 130 6 18 170 Example 6 60 15 10 30 180 6 18 170 Example 7 90 20 15 30 180 6 24 190 Example 8 90 25 15 60 180 10 24 190 Example 9 90 30 20 60 200 10 24 210 Comparative Example 1 - - - - - - - - Comparative Example 2 - - 15 30 180 6 24 190

Electrical Conductivity (S / cm) Example 1 1.193 Example 2 2.874 Example 3 4.532 Example 4 5.854 Example 5 6.082 Example 6 7.661 Example 7 8.056 Example 8 7.080 Example 9 6.990 Comparative Example 1 - Comparative Example 2 0.929

Having described specific portions of the present invention in detail, those skilled in the art will appreciate that these specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (5)

(a) plating the carbon fiber by immersing the pitch-based carbon fiber in a metal plating solution;
(b) preparing a carbon fiber web by mixing the plated carbon fibers with an organic polymer compound by a wet process;
(c) impregnating the carbon fiber web with the thermosetting resin; And
(d) curing the impregnated carbon fiber web.
The method according to claim 1,
Wherein the plating temperature in step (a) is 30 to 90 占 폚.
The method according to claim 1,
Wherein the organic polymer compound is polyvinyl alcohol in the step (b).
The method according to claim 1,
Wherein the concentration of the organic polymer compound in the step (b) is 1 to 20 weight ratio to the pitch-based carbon fiber.
The method according to claim 1,
Wherein the thermosetting resin is one selected from the group consisting of phenol resin, urea resin, melamine resin, epoxy resin, and unsaturated polyester resin in the step (c).

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