COMPOSITE MATERIAL

Abstract

The present application relates to a composite material, a method for producing the same, and an electromagnetic-wave shielding sheet comprising the same, which can provide a composite material having excellent impact resistance and processability while having excellent heat dissipation performance, a method for producing the composite material, and an electromagnetic-wave shielding sheet.

Claims

1. A composite material comprising a metal foam in the form of a film and a graphene component present on a surface of the metal foam or inside the metal foam, wherein the metal foam comprises pores, the pores having a size of 10 μm or less on average based on a long axis of each of the pores.

2. The composite material according to claim 1, wherein the graphene component is included in a range of 10.sup.−5 to 10.sup.−1 wt % in the composite material.

3. The composite material according to claim 1, wherein the metal foam has a thickness in a range of 10 μm to 1000 μm.

4. The composite material according to claim 1, wherein the metal foam comprises a metal or a metal alloy having a thermal conductivity of 8 W/mK or greater.

5. The composite material according to claim 1, wherein the metal foam comprises one or more metals or metal alloys selected from the group consisting of iron, cobalt, nickel, copper, phosphorus, molybdenum, zinc, manganese, chromium, indium, tin, silver, platinum, gold, aluminum, stainless steel and magnesium.

6. The composite material according to claim 1, wherein the metal foam has a porosity in a range of 30% to 99%.

7. The composite material according to claim 1, further comprising a polymer component present on the surface of the metal foam or on the graphene component.

8. The composite material according to claim 7, wherein the polymer component forms a surface layer on the surface of the metal foam or on the graphene component.

9. The composite material according to claim 7, wherein the polymer component comprises one or more resins selected from the group consisting of an acrylic resin, a silicone resin, an epoxy resin, a urethane resin, an amino resin and a phenol resin.

10. The composite material according to claim 1, wherein the graphene component forms a graphene layer on the surface of the metal foam or inside the metal foam.

11. The composite material according to claim 10, wherein the graphene layer has a thickness in a range of 10 nm or less.

12. The composite material according to claim 1, wherein the composite material has a thermal conductivity of about 0.4 W/mK or greater.

13. A method for producing the composite material according to claim 1, the method comprising: providing the metal foam; and forming the graphene component on the surface of or inside the metal foam in the form of a film.

14. An electromagnetic wave shielding sheet comprising a metal foam in the form of a sheet and a graphene component present on a surface of the metal foam or inside the metal foam, wherein the metal foam comprises pores, the pores having a size of 10 μm or less on average based on a long axis of each of the pores.

15. The electromagnetic wave shielding sheet according to claim 14, wherein the graphene component is included in a range of 10.sup.−5 to 10.sup.−1 wt % in the sheet.

16. The method of claim 13, wherein said forming is carried out by chemical vapor deposition (CVD) of the graphene component on the surface of the metal foam or inside the metal foam.

17. The method of claim 16, wherein the chemical vapor deposition (CVD) comprises high temperature chemical vapor deposition (HTCVD), inductively coupled plasma chemical vapor deposition (ICP-CVD), low pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), metal organic chemical vapor deposition (MOCVD) or plasma-enhanced chemical vapor deposition (PECVD).

Description

BRIEF DESCRIPTION OF DRAWINGS

[0067] FIGS. 1 and 2 are SEM images of metal foams according to Examples 6 and 7.

[0068] FIG. 3 is a graph showing electromagnetic wave shielding efficiency of Example 6 and Comparative Example 7.

BEST MODE

[0069] Hereinafter, the present application will be described in detail with reference to examples and comparative examples, but the scope of the present application is not limited to the following examples.

Example 1

[0070] The metal foam was a copper metal foam, where the copper foam in a film shape with a thickness of about 80 μm or so, an average pore size of 5 μm and a porosity of about 70% was used. In order to remove the oxide film on the surface of the copper foam, it was heated to 1000° C. in the presence of reducing gas (H.sub.2) for 2 hours. Thereafter, CH.sub.4 gas was injected and heated at 1000° C. for 6 hours to deposit graphene. It was confirmed through Raman analysis whether or not the graphene was deposited.

[0071] The graphene-deposited copper foam as produced above was immersed in a thermosetting resin (Dow Corning, PDMS, Sylgard 527kit) solution, and then extruded to a thickness of 100 μm using a film applicator to remove an excessive amount of the resin. Thereafter, it was cured in an oven at 120° C. for 2 hours to produce a composite material having a thickness of 100 μm.

Example 2

[0072] A composite material was produced in the same manner as in Example 1, except that the thickness of the copper foam was 100 μm and the final composite material was produced to have a thickness of about 120 μm or so.

Example 3

[0073] A composite material was produced in the same manner as in Example 1, except that the thickness of the copper foam was 120 μm and the final composite material was produced to have a thickness of about 140 μm or so.

Example 4

[0074] A composite material was produced in the same manner as in Example 2, except that the metal foam was produced to have a porosity of about 60% or so.

Example 5

[0075] A composite material was produced in the same manner as in Example 2, except that the metal foam was produced to have a porosity of about 50% or so.

Example 6

[0076] The metal foam was a copper metal foam, where the copper foam in a film shape with a thickness of about 90 μm or so and a porosity of about 62% was used. FIG. 1 shows an SEM image (left) and a pore size distribution graph (right) of the metal foam according to Example 6.

[0077] The copper foam was reduced at 1000° C. for 1 hour under H.sub.2 atmosphere. Thereafter, the partial pressure of the gas was changed to H.sub.2/CH.sub.4=15/50 to grow graphene at 1000° C. for 20 minutes, and while the temperature was gradually lowered to room temperature under H.sub.2 atmosphere, the graphene-deposited copper foam was formed to produce an electromagnetic wave shielding sheet according to the present application.

Example 7

[0078] An electromagnetic wave shielding sheet was produced in the same manner as in Example 6, except that the metal foam was a copper metal foam, where the copper foam in a film shape with a thickness of about 100 μm or so and a porosity of about 65% was used. FIG. 2 shows an SEM image (left) and a pore size distribution graph (right) of the metal foam according to Example 7.

Comparative Example 1

[0079] After a copper filler was mixed with a PDMS resin as a metal filler, the mixture was molded using a film applicator into the form of a film having a thickness of about 120 μm or so and cured to produce a composite material in the form of a film.

Comparative Example 2

[0080] After a graphite filler was mixed with a PDMS resin as a metal filler, the mixture was molded using a film applicator into the form of a film having a thickness of about 120 μm or so and cured to produce a composite material in the form of a film.

Comparative Example 3

[0081] After a CNT filler was mixed with a PDMS resin as a metal filler, the mixture was molded using a film applicator into the form of a film having a thickness of about 120 μm or so and cured to produce a composite material in the form of a film.

Comparative Example 4

[0082] A copper foam was produced by plating copper on a polyurethane foam and then baking it at high temperature to remove the polyurethane. The produced copper foam had an average pore size of 450 μm, a porosity of 95% or more and a thickness of 1.6 mm.

[0083] A composite material was produced by depositing graphene on the copper foam in the form of a film in the same manner as in Example 1.

Comparative Example 5

[0084] A composite material was produced in the same manner as in Comparative Example 4, except for depositing no graphene.

Comparative Example 6

[0085] A composite material was produced in the same manner as in Example 2, except for forming no graphene.

Comparative Example 7

[0086] An electromagnetic wave shielding sheet was produced in the same manner as in Example 6, except for depositing no graphene.

Experimental Example 1-Thermal Conductivity Measurement

[0087] By obtaining thermal diffusivity (A), specific heat (B), and density (C) of the composite material, the thermal conductivity of each composite material produced according to Examples and Comparative Examples was obtained by an equation of thermal conductivity=ABC, where the thermal diffusivity (A) was measured using a laser flash method (LFA equipment, model name: LFA467), the specific heat was measured using DSC (differential scanning calorimeter) equipment, and the density was measured using the Archimedes method. In addition, the thermal conductivity is a value for the thickness direction (Z axis) of the composite material.

TABLE-US-00001 TABLE 1 Thermal conductivity (W/mK) Remarks Example 1 5.11 — Example 2 5.16 — Example 3 5.01 — Example 4 5.55 — Example 5 5.87 — Comparative Example 1 0.37 — Comparative Example 2 0.34 — Comparative Example 3 0.47 — Comparative Example 4 1.77 — Comparative Example 5 1.71 Comparative Example 6 3.41 —

Experimental Example 2-Measurement of Electromagnetic Wave Shielding Efficiency

[0088] For each electromagnetic wave shielding sheet produced in Examples 6 and 7, and Comparative Example 7, the electromagnetic wave shielding efficiency was measured using an electromagnetic wave shielding efficiency measuring apparatus from Keycom. FIG. 3 showed the results of measuring the shielding efficiency from 300 MHz to 3 GHz for Example 6 (graphene-deposited copper foam) and Comparative Example 7 (copper foam without graphene deposition). In the case of Comparative Example, as shown in FIG. 3, the shielding efficiency decreased as the frequency was increased, whereas in the case of Example 6, it reached 100 dB as the instrument measurement limit.