Composite material and preparation method therefor

Abstract

According to the present invention, a composite material can be provided having a small thickness, excellent elasticity, high thermal conductivity, and outstanding durability by filling internal pores of a porous substrate with a conductive polymer and reduced graphene oxide. The composite material according to the present invention can be used as a thermal pad to further enhance the performance of an electronic equipment heat sink module.

Description

Composite material and method for manufacturing the same

[0001] The present invention relates to a composite material used as a thermal pad and a method for manufacturing the same.

[0002] Thermal Interface Material (TIM) is a material applied or inserted between a heating element such as a semiconductor chip and a heat sink to reduce the contact thermal resistance that occurs between the two. It is mainly used to dissipate local heat generated in electronic equipment, electric vehicles, and communication equipment.

[0003] There are several types of thermal interface materials, including thermal pads, thermal pastes, thermal tapes, and phase change materials (PCMs). The most commonly known types are thermal pads and thermal pastes.

[0004] A thermal pad is a thermal interface material in the form of a pad with a fixed solid form, and is distinguished from thermal paste, which is a thermal interface material in the form of a liquid or paste. Unlike thermal paste, which is applied between a heating element and a heat sink, a thermal pad is inserted between a heating element and a heat sink and its form does not change.

[0005] Thermal pads have the advantage of not having the disadvantages of thermal paste (the application and removal process is messy, and excessive paste can leak into the surroundings, polluting the environment or causing an electrical short in severe cases) because their shape does not change. However, they have the disadvantages of being thick, having high thermal resistance, low thermal conductivity, and having poor elasticity, making it difficult to fold and store.

[0006] The present invention is intended to solve the above problem, and aims to provide a composite material that is thin, has excellent elasticity, has high thermal conductivity, and is also durable.

[0007] One aspect of the present invention relates to a composite material comprising a porous substrate, a conductive polymer, and reduced graphene oxide, wherein the porous substrate has a porosity of 50% or more, and each of the conductive polymer and the reduced graphene oxide is contained in a pore within the porous substrate or at least on one surface of the porous substrate.

[0008] In one embodiment, the porous substrate may be characterized as being Korean paper.

[0009] In one embodiment, the paper may be characterized as being a ceremonial paper.

[0010] In one embodiment, the porous substrate may be characterized by having a thickness of 0.05 mm to 1 mm.

[0011] In one embodiment, the porous substrate may be characterized by having a thickness of 0.15 mm to 0.17 mm.

[0012] In one embodiment, the porous substrate may be characterized by a porosity of 54% to 58%.

[0013] In one embodiment, the conductive polymer may be characterized by being at least one selected from the group consisting of Poly(vinyl butyral-co-vinyl alcohol-covinyl acetate), Poly(p-phenylene), Polypyrrol (PPy), Polythiophene, Poly(p-phynylene vinylene), Polyacetylyne, Polyaniline (PANI), and Poly(3,4-ethylenedioxythiophene) (PEDOT).

[0014] In one embodiment, the conductive polymer may be characterized as being Poly(vinyl butyral-co-vinyl alcohol-covinyl acetate).

[0015] In one embodiment, the conductive polymer may be included in an amount of 50 to 500 parts by weight relative to 100 parts by weight of the porous substrate.

[0016] In one embodiment, the reduced graphene may be included in an amount of 0.1 to 10 parts by weight relative to 100 parts by weight of the porous substrate.

[0017]

[0018] In one embodiment, the composite of the present invention may be characterized by a thickness of 0.2 mm or less.

[0019] In one embodiment, the composite of the present invention may be characterized by a thickness of 0.15 mm to 0.17 mm.

[0020] In one embodiment, the composite of the present invention may be characterized by a thermal conductivity of 5 W / mK or greater.

[0021] In one embodiment, the composite of the present invention may be characterized as being used as a thermal pad.

[0022] Another aspect of the present invention relates to a method for producing a composite, comprising the steps of: applying a dispersion containing a conductive polymer to a porous substrate and drying it; and applying a reduced graphene oxide aqueous solution and drying it; wherein the porous substrate has a porosity of 50% or more, and a weight ratio of the reduced graphene to the reduced graphene oxide aqueous solution is 0.01 to 0.2 wt%.

[0023] In one embodiment, in the step of applying and drying a dispersion containing a conductive polymer to the porous substrate, the application may be performed at a speed of 5 to 15 cm / s.

[0024] In one embodiment, in the step of applying and drying a dispersion containing a conductive polymer to the porous substrate, the drying may be performed at a temperature of 40 to 80° C. for 5 minutes or less.

[0025] In one embodiment, in the step of applying and drying the reduced graphene solution, the step of applying the reduced graphene solution may be characterized in that it is performed at a speed of 5 to 15 cm / s.

[0026] In one embodiment, in the step of applying and drying the reduced graphene oxide aqueous solution, the drying may be characterized in that it is performed at a temperature of 40 to 80° C. for more than 5 minutes.

[0027] According to the present invention, the internal pores of a porous substrate can be filled with a conductive polymer and reduced graphene oxide to provide a composite material that is thin, highly elastic, yet possesses high thermal conductivity and durability. The composite material according to the present invention can be used as a thermal pad to further enhance the performance of electronic equipment heat dissipation modules.

[0028] Figure 1 is an image of the structure of the embodiment taken using a scanning electron microscope (SEM).

[0029] Figure 2 is a graph showing the results of evaluating the durability of Example 2 and Comparative Example 3.

[0030] According to one embodiment, a composite material includes a porous substrate, a conductive polymer, and reduced graphene oxide, wherein the porous substrate has a porosity of 50% or more, and each of the conductive polymer and the reduced graphene oxide is contained in a pore within the porous substrate or at least on one surface of the porous substrate.

[0031] According to another embodiment, a method for manufacturing a composite material includes the steps of applying a dispersion containing a conductive polymer to a porous substrate and drying it; and applying a reduced graphene oxide aqueous solution and drying it; wherein the porous substrate may have a porosity of 50% or more, and a weight ratio of the reduced graphene to the reduced graphene oxide aqueous solution may be 0.01 to 0.2 wt%.

[0032] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0033] Accordingly, the configuration of the embodiments described in this specification is only one of the most preferred embodiments of the present invention and does not represent all of the technical ideas of the present invention, so it should be understood that various equivalents and modified examples that can replace them may exist at the time of filing this application.

[0034] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0035] When a part in this specification is said to "comprise" a certain component, this does not mean that other components are excluded, but rather that other components may be included, unless specifically stated otherwise. Thus, for example, a composition comprising Compound A may comprise compounds other than A. However, the term "comprise" also encompasses, as a specific embodiment thereof, the more restrictive meanings of "consisting essentially / essentially of" and "consisting of," so that, for example, "a composition comprising Compound A" may also consist (essentially / essentially) of Compound A.

[0036] In this connection, it should be understood that terms such as “have” or “have” as used herein are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0037] When it is said in this specification that any element is located "on" another element, this includes not only cases where such element is in contact with the other element, but also cases where another element or material exists between the two elements.

[0038] Where an amount, concentration, or other value or parameter is given herein as a range, a preferred range, or an enumeration of an upper preferred value and a lower preferred value, this should be understood to specifically disclose any range that can be formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the range is separately disclosed. Where a range of numerical values ​​is recited herein, unless otherwise stated, e.g., there is no limiting term such as greater than, less than, etc., the range is intended to include the endpoint values ​​and all integers and fractions within the range. The scope of the present invention is not intended to be limited to the specific values ​​recited when defining a range.

[0039] Among the properties mentioned in this specification, if the measurement temperature affects the property, the property is measured at room temperature unless otherwise specified. The term "room temperature" refers to the natural temperature without heating or cooling, and may mean, for example, any temperature within the range of about 10°C to 30°C, or about 23°C or about 25°C. In addition, unless otherwise specified, the unit of temperature in this specification is ℃.

[0040] In addition, among the properties mentioned in this specification, if the measurement pressure affects the property, the property is measured at normal pressure, i.e., atmospheric pressure (approximately 1 atm), unless otherwise specified.

[0041] The first aspect of the present invention relates to a composite material.

[0042] The composite of the present invention may be characterized in that it includes, for example, a porous substrate, a conductive polymer, and reduced graphene oxide, wherein the porous substrate has a porosity of 50% or more, and each of the conductive polymer and the reduced graphene oxide is contained in a pore within the porous substrate or at least on one surface of the porous substrate.

[0043] In one embodiment, the porous substrate may be characterized as being made of Korean paper, and more preferably, the Korean paper may be characterized as being made of Daerye Korean paper.

[0044] In one embodiment, the porous substrate may have a porosity of 50% or more, and in other examples, 52% or more, 54% or more, or 56% or more, or 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, or 60% or less. The present invention can provide a composite material having excellent elasticity, thermal conductivity, and durability through the combination of a conductive polymer and reduced graphene with the porous substrate by introducing a porous substrate having a porosity in the above range.

[0045] In one embodiment, the thickness of the porous substrate may be characterized as being 0.05 mm to 1 mm. In other examples, the thickness may be 0.07 mm or more, 0.09 mm or more, 0.11 mm or more, 0.13 mm or more, or 0.15 mm or more, or 0.9 mm or less, 0.8 mm or less, 0.7 mm or less, 0.6 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, or 0.2 mm or less. The present invention can provide a composite material having excellent elasticity, etc. by controlling the thickness of the porous substrate to be within the above range.

[0046] In one embodiment, the composite of the present invention may be characterized in that each of the conductive polymer and the reduced graphene is contained within the pores within the porous substrate. The conductive polymer and the reduced graphene are uniformly distributed within each of the pores within the porous substrate, thereby enhancing durability and thermal conductivity.

[0047] In one embodiment, the conductive polymer may be characterized by being at least one selected from the group consisting of Poly(vinyl butyral-co-vinyl alcohol-covinyl acetate), Poly(p-phenylene), Polypyrrol (PPy), Polythiophene, Poly(p-phynylene vinylene), Polyacetylyne, Polyaniline (PANI), and Poly(3,4-ethylenedioxythiophene) (PEDOT). Since the composite of the present invention includes the conductive polymer as described above, the reduced graphene oxide can be better composited with the porous substrate, thereby providing excellent durability and improving thermal conductivity. In addition, by using P(VB-co-VA-co-Vac) as the conductive polymer, not only price competitiveness but also compatibility with the reduced graphene oxide and the porous substrate can be improved.

[0048] In one embodiment, the conductive polymer may be included in an amount of 50 to 500 parts by weight relative to 100 parts by weight of the porous substrate. In another embodiment, the conductive polymer may be included in an amount of 100 parts by weight or more, 150 parts by weight or more, or 200 parts by weight or more, or 450 parts by weight or less, 400 parts by weight or less, 350 parts by weight or less, or 300 parts by weight or less, relative to 100 parts by weight of the porous substrate. By including the conductive polymer in the porous substrate in the weight ratio as described above, it is possible to provide a composite material having excellent elasticity and excellent electrical conductivity.

[0049] In one embodiment, the reduced graphene may be included in an amount of 0.1 to 10 parts by weight relative to 100 parts by weight of the porous substrate. In another embodiment, the reduced graphene may be included in an amount of 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, or 0.9 parts by weight or more, or 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, or 2 parts by weight or less, relative to 100 parts by weight of the porous substrate. By including the reduced graphene in the above weight ratio relative to the porous substrate, it is possible to provide a composite material having excellent conductivity and durability through combination with a conductive polymer.

[0050] In one embodiment, the composite of the present invention may be characterized by a thickness of 0.2 mm or less. In other examples, the composite of the present invention may have a thickness of 0.19 mm or less, 0.18 mm or less, or 0.17 mm or less, or 0.01 mm or more, 0.05 mm or more, 0.1 mm or more, or 0.15 mm or more. The thickness may be measured in a manner according to the evaluation examples described below, but is not limited thereto. The composite of the present invention has excellent thermal conductivity and excellent elasticity due to its thin thickness as described above, thereby facilitating storage, etc.

[0051] In one embodiment, the composite of the present invention may be characterized by a thermal conductivity of 5 W / mK or greater. In other examples, the composite of the present invention may have a thermal conductivity of 5.5 W / mK or greater, 6.0 W / mK or greater, or 6.5 W / mK or greater, or 20 W / mK or less, 15 W / mK or less, or 10 W / mK or less. The thermal conductivity may be measured in a manner according to the evaluation examples described below, but is not limited thereto.

[0052] In one embodiment, the composite of the present invention may be characterized as being used as a thermal pad. By using the composite of the present invention as a thermal pad, the performance of an electronic equipment heat dissipation module can be further improved and the stability can be increased.

[0053] The second aspect of the present invention relates to a method for manufacturing a composite material.

[0054] Matters relating to the first aspect of the present invention may be equally applied to matters relating to the second aspect, unless specifically stated otherwise.

[0055] The method for manufacturing a composite of the present invention includes, for example, a step of applying a dispersion containing a conductive polymer to a porous substrate and drying it; and a step of applying a reduced graphene oxide aqueous solution and drying it; wherein the porous substrate may have a porosity of 50% or more, and a weight ratio of the reduced graphene to the reduced graphene oxide aqueous solution may be 0.01 to 0.2 wt%.

[0056] In one embodiment, the weight ratio of the reduced graphene to the reduced graphene aqueous solution may be, in other examples, 0.02 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, 0.06 wt% or more, 0.07 wt% or more, 0.08 wt% or more, or 0.09 wt% or more, or 0.19 wt% or less, 0.18 wt% or less, 0.17 wt% or less, 0.16 wt% or less, 0.15 wt% or less, 0.14 wt% or less, 0.13 wt% or less, 0.12 wt% or less, or 0.11 wt% or less. By setting the weight ratio of the reduced graphene to the reduced graphene aqueous solution within the above range, a composite material having high price competitiveness and excellent thermal conductivity can be provided.

[0057] In one embodiment, the weight ratio of the conductive polymer to the dispersion containing the conductive polymer may be in the range of 1 to 20 wt%. In other examples, the weight ratio of the conductive polymer to the dispersion containing the conductive polymer may be 2 wt% or more, 3 wt% or more, 4 wt% or more, 5 wt% or more, 6 wt% or more, 7 wt% or more, 8 wt% or more, or 9 wt% or less, 19 wt% or less, 18 wt% or less, 17 wt% or less, 16 wt% or less, 15 wt% or less, 14 wt% or less, 13 wt% or less, 12 wt% or less, or 11 wt% or less.

[0058] In one embodiment, in the step of applying and drying a dispersion containing a conductive polymer to the porous substrate, the application may be characterized in that it is performed at a speed of 5 to 15 cm / s. In the step of applying and drying a dispersion containing a conductive polymer to the porous substrate, the application may be performed at a speed of 7 cm / s or more or 9 cm / s or more, or at a speed of 13 cm / s or less or 11 cm / s or less, in another example.

[0059] In one embodiment, in the step of applying and drying a dispersion containing a conductive polymer to the porous substrate, the drying may be performed at a temperature of 40 to 80°C for 5 minutes or less. The drying temperature may be, but is not limited to, 50 to 70°C or 55 to 65°C in other examples. The drying time may be, but is not limited to, 4 minutes or less, 3 minutes or less, or 2 minutes or less, or 30 seconds or more in other examples.

[0060] In one embodiment, in the step of applying and drying the reduced graphene aqueous solution, the step of applying the reduced graphene aqueous solution may be characterized in that it is performed at a speed of 5 to 15 cm / s. In the step of applying and drying the reduced graphene aqueous solution, the step of applying the reduced graphene aqueous solution may be performed at a speed of 7 cm / s or more or 9 cm / s or more, or at a speed of 13 cm / s or less or 11 cm / s or less, in another example.

[0061] In one embodiment, in the step of applying and drying the reduced graphene oxide aqueous solution, the drying may be performed at a temperature of 40 to 80°C for more than 5 minutes. The drying temperature may be, but is not limited to, 50 to 70°C or 55 to 65°C in other examples. The drying time may be, but is not limited to, 6 minutes or more, 7 minutes or more, 8 minutes or more, or 9 minutes or more, or 20 minutes or less, or 15 minutes or less in other examples.

[0062] Hereinafter, the present invention will be described in detail by way of examples to specifically illustrate the disclosure of the present invention and its intended functions and effects, as described above. However, these examples may be modified in various ways, and the scope of this specification is not construed as being limited to these examples. It is emphasized that these examples are provided to represent the present invention and to provide a more concrete explanation to those skilled in the art.

[0063] Example.

[0064] Polymer dispersion was bar-coated on Hanji (Daerye Hanji, porosity 57%, thickness 0.16 mm) using a bar coater (Meyor Rod&Air Knife Coater) at a speed of 10 cm / s and a thickness of 0.2 mm. At this time, the polymer dispersion used was Poly(vinyl butyral-co-vinyl alcohol-covinyl acetate) dispersed in ethanol at a weight ratio of 1:9 (Poly(vinyl butyral-co-vinyl alcohol-covinyl acetate):ethanol). Subsequently, the coated Hanji was dried at 60°C for approximately 1 minute.

[0065] After that, a reduced graphene oxide aqueous solution (0.1 wt%, CBBScientific Co., Ltd.) was coated using the above bar coater at a speed of 10 cm / s and a thickness setting of 0.2 mm, and then dried at 60°C for about 10 minutes to produce a composite. At this time, the reduced graphene oxide aqueous solution was used, which was prepared by reducing graphene oxide flakes produced through the modified Hummer's method to produce reduced graphene oxide flakes, and then dispersing them in water.

[0066] The manufactured composite was a composite in which conductive polymer and reduced graphene oxide were filled in the internal pores of Hanji. The thickness of the composite was approximately 0.16 mm, the thermal conductivity was 6.78 W / mK, and the weight ratio of Hanji: polymer (Poly(vinyl butyral-co-vinyl alcohol-covinyl acetate)): reduced graphene was 120:300:3.

[0067] Comparative Example 1.

[0068] A composite was manufactured in the same manner as Example 1, except that Daesung Co., Ltd.'s Aqua Satin coated paper (30% porosity, 0.15 mm thickness) was used instead of Hanji (Daerye Hanji, 57% porosity, 0.16 mm thickness).

[0069] The manufactured composite was a composite in which conductive polymer and reduced oxide graphene were filled in the internal pores of aqua satin coated paper, and the thickness of the manufactured composite was approximately 0.15 mm and the thermal conductivity was 4.35 W / mK.

[0070] Comparative Example 2.

[0071] A composite was manufactured in the same manner as in Example 1, except that commonly used cardboard (48% porosity, 0.23 mm thickness) was used instead of Korean paper (Daerye Korean paper, 57% porosity, 0.16 mm thickness).

[0072] The manufactured composite was a composite in which conductive polymer and reduced graphene were filled in the internal pores of cardboard, and the thickness of the manufactured composite was approximately 0.23 mm and the thermal conductivity was 5.71 W / mK.

[0073] Comparative Example 3.

[0074] A composite was manufactured in the same manner as in Example 1, except that the polymer dispersion was not treated on the Korean paper.

[0075] The manufactured composite was a composite in which only reduced oxide graphene was filled in the internal pores of Korean paper. The thickness of the manufactured composite was approximately 0.15 mm, and the thermal conductivity was 3.56 W / mK.

[0076] Comparative Example 4.

[0077] A composite was manufactured in the same manner as in Example 1, except that a graphite nanoplatelet (GNP) aqueous dispersion (0.1 wt%) was used instead of a reduced graphene aqueous solution (0.1 wt%, CBB Science Co., Ltd.).

[0078] The manufactured composite was a composite in which conductive polymer and graphene nanoplates were filled in the internal pores of Hanji. The thickness of the manufactured composite was approximately 0.16 mm and the thermal conductivity was 2.56 W / mK.

[0079]

[0080] Evaluation Example 1. Thickness of composite material

[0081] The thickness of each composite material in the above examples and comparative examples was measured using a thickness gauge (MISUMI). During the measurement, the thickness was measured at five arbitrary points on the composite material, and the average of these thicknesses was used as the thickness of the composite material.

[0082] Evaluation Example 2. Thermal Conductivity of Composite Materials

[0083] The thermal conductivity of each composite material of the above examples and comparative examples was measured by the Laser Flash Method using LINSEIS XFA 300.

[0084] - Temp. range: 60℃ setup, equipment specifications are room temperature to 300℃

[0085] - Diffusivity measuring range (mm 2 / s) : 0.01~1000 mm 2 / s

[0086] - Conductivity measuring range(W / mK): 0.1-2000 W / mK

[0087] - Thermal Diffusivity Repeatability: 2%

[0088] - IR Source: Xenon Flash Lamp

[0089] - Sample size: thickness 0.1 mm to 6 mm, sample diameter 10 mm, 12.7 mm, 25.4 mm possible

[0090] Evaluation Example 3. Structure of composite material

[0091] The structure of the composite material of the above example was confirmed through a scanning electron microscope (SEM). As shown in the SEM image, the microscopic pores of the Korean paper were filled with P(VB-co-VA-co-Vac) and reduced graphene oxide to form a composite, as shown in Fig. 1.

[0092] Evaluation Example 4. Durability of composite materials

[0093] The durability of the composites of the above examples and comparative example 3 was confirmed by visually observing whether reduced graphene oxide was removed from the tape before and after attaching the tape to the composite, and by measuring thermal conductivity.

[0094] As a result of the evaluation, in the case of Comparative Example 3, which was not treated with a conductive polymer, reduced graphene was found to come off the tape after the tape was attached and then removed. In addition, as shown in Fig. 2, the thermal conductivity after the tape was attached and then removed decreased compared to before the tape was attached. On the other hand, in the case of the Example, reduced graphene was not found to come off the tape even after the tape was attached and then removed. In addition, as shown in Fig. 2, the thermal conductivity after the tape was attached and then removed was the same as before the tape was attached.

[0095] Through this, it was confirmed that the embodiment had superior durability compared to comparative example 3.

Claims

Containing a porous substrate, a conductive polymer and reduced graphene oxide, The above porous substrate has a porosity of 50% or more, A composite material, characterized in that each of the conductive polymer and the reduced graphene is contained in a void within the porous substrate or at least on one surface of the porous substrate. A composite material, characterized in that the porous substrate in claim 1 is Korean paper. A composite material, characterized in that the paper in the second paragraph is a Daerye paper. In the first paragraph, a composite material characterized in that the thickness of the porous substrate is 0.05 mm to 1 mm, A composite material according to claim 1, characterized in that the conductive polymer is at least one selected from the group consisting of Poly(vinyl butyral-co-vinyl alcohol-covinyl acetate), Poly(p-phenylene), Polypyrrol (PPy), Polythiophene, Poly(p-phynylene vinylene), Polyacetylyne, Polyaniline (PANI), and Poly(3,4-ethylenedioxythiophene) (PEDOT). A composite material, characterized in that in claim 1, the conductive polymer is included in an amount of 50 to 500 parts by weight per 100 parts by weight of the porous substrate. A composite material, characterized in that in claim 1, the reduced oxide graphene is included in an amount of 0.1 to 10 parts by weight relative to 100 parts by weight of the porous substrate. A composite material characterized in that the thickness of the first clause is 0.2 mm or less. A composite material characterized in that the thermal conductivity of the first clause is 5 W / mK or more. A composite material characterized in that it is used as a thermal pad in claim 1. A step of applying a dispersion containing a conductive polymer to a porous substrate and drying it; and A step of applying and drying a reduced oxide graphene solution; including; The above porous substrate has a porosity of 50% or more, A method for producing a composite, characterized in that the weight ratio of the reduced oxide graphene to the reduced oxide graphene aqueous solution is 0.01 to 0.2 wt%. A method for manufacturing a composite material, characterized in that in the step of applying and drying a dispersion containing a conductive polymer to the porous substrate in the 11th paragraph, the application is performed at a speed of 5 to 15 cm / s. A method for manufacturing a composite material, characterized in that in the step of applying and drying a dispersion containing a conductive polymer to the porous substrate in the 11th paragraph, the drying is performed at a temperature of 40 to 80°C for 5 minutes or less. A method for manufacturing a composite material, characterized in that in the step of applying and drying the reduced graphene solution in the 11th paragraph, the step of applying the reduced graphene solution is performed at a speed of 5 to 15 cm / s. A method for manufacturing a composite material, characterized in that in the step of applying and drying the reduced oxide graphene solution in claim 11, the drying is performed at a temperature of 40 to 80°C for more than 5 minutes.

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