KR102340427B1 - Composite for fuel cell bipolar plate and its preparation method - Google Patents

Abstract

The present invention relates to a composite for a fuel cell separator and a method for manufacturing the same, and more particularly, a thermosetting resin containing sulfide or fluorine, a thermosetting resin-graphite nanoplatelet masterbatch, and a fuel fuel ratio in which graphite is laminated It relates to a composite for a separator and a method for manufacturing the same.
The present invention provides a composite for a fuel cell separator and a method for manufacturing the same, so that it has resistance to high temperature and high concentration of phosphoric acid compared to a conventional fuel cell separator, and can secure excellent electrical and thermal conductivity, and graphite in the composite There is an effect excellent in the dispersibility and uniformity of the nanoplatelet particles.

Description

Composite for fuel cell bipolar plate and its preparation method {Composite for fuel cell bipolar plate and its preparation method}

The present invention relates to a composite for a fuel cell separator and a method for manufacturing the same, and more particularly, a thermosetting resin containing sulfide or fluorine, a thermosetting resin-graphite nanoplatelet masterbatch, and a fuel fuel ratio in which graphite is laminated It relates to a composite for a separator and a method for manufacturing the same.

The fuel cell is a cogeneration technology that produces heat and electricity, and has the highest power generation efficiency among the candidates for distributed power generation. It is characterized by very low harmful substances in the exhaust gas compared to other power generation systems by reforming hydrocarbon-based fuel into hydrogen. . In Korea, fuel cells have already secured a considerable technological level, and an example of this is the polymer electrolyte fuel cell (PEMFC). Since PEMFC has a simple structure, it is easy to manufacture, has almost no corrosion problem, has high space efficiency, and has high energy density and efficiency. However, PEMFC has fundamental problems such as a complicated humidification system and performance degradation due to flooding in the stack.

Phosphoric acid fuel cell (PAFC) has the same power generation principle as this PEMFC, but it is more advantageous in terms of power generation efficiency and heat utilization by operating at 180 to 250 ° C, unlike the existing PEMFC operated at a relatively low temperature of 60 to 80 ° C. There are advantages. However, due to the characteristics of operation in a relatively high temperature and phosphoric acid environment, the performance of the components constituting the stack and the separator plate is required to a higher and stricter level.

Accordingly, 'Korea Patent Publication No. 10-2010-0070823' provides a composition for a fuel cell separator that can improve electrical conductivity and is easier to manufacture than a conventional graphite separator, but the strength, thermal stability and There is a problem in that the same functions are not secured, only electrical properties are improved, and improvements in physical properties are not disclosed at all.

Accordingly, an object of the present invention is to provide a composite for a fuel cell separator that can be utilized not only in a general polymer electrolyte fuel cell (PEMFC) but also in a phosphoric acid fuel cell (PAFC) requiring a higher level of performance.

KR 10-2010-0070823 A KR 10-2013-0014205 A

In order to solve the above problems, the present invention provides a fuel that can secure excellent thermal and electrical conductivity and is easy to mold by including a thermosetting resin containing sulfide or fluorine, a thermosetting resin-graphite nanoplatelet masterbatch, and graphite An object of the present invention is to provide a composite for a battery separator.

Another object of the present invention is to provide a method for manufacturing a composite for a fuel cell separator.

The present invention in order to solve the above object,

a thermoplastic resin including sulfide or fluorine;

a thermoplastic resin-graphite nanoplatelet masterbatch formed of a thermoplastic resin containing sulfide or fluorine and graphite nanoplatelet (GNP); and

Graphite (graphite); including,

The masterbatch is a form in which a thermoplastic resin is bonded on the surface of the graphite nanoplatelet,

It provides a composite for a fuel cell separator, characterized in that the thermoplastic resin, the masterbatch, and the graphite are laminated.

The thermoplastic resin is polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene (FEP), and polyfluoroalkoxyethylene copolymer. It is characterized in that at least one selected from among polyfluoroalkoxyethylene copolymers, the thermoplastic resin, masterbatch, and graphite are in powder form, and the composite contains 70 to 90% by weight of carbon.

The present invention in order to solve the other object,

A first step of uniformly mixing a thermoplastic resin and graphite nanoplatelet (GNP) to form a mixture;

a second step of stirring the mixture at a high temperature to form a masterbatch; and

A third step of mixing the masterbatch and graphite through ball milling to form a reactant;

The thermoplastic resin provides a method of manufacturing a composite for a fuel cell separator, characterized in that it contains sulfide or fluorine.

The first step is characterized in that the thermoplastic resin and the graphite nanoplatelet are pulverized and uniformly mixed, and the manufacturing method further comprises the step of compressing the reactant.

The present invention provides a composite for a fuel cell separator and a method for manufacturing the same, so that it has resistance to high temperature and high concentration of phosphoric acid compared to a conventional fuel cell separator, and can secure excellent electrical and thermal conductivity, and graphite in the composite There is an effect excellent in the dispersibility and uniformity of the nanoplatelet particles.

1 is a view showing a manufacturing process of a master batch according to an embodiment of the present invention.
2 is a view showing a manufacturing process of a composite according to an embodiment and a comparative example of the present invention.
3 is a graph showing the particle size distribution according to the presence or absence of pulverization of the PPS of an embodiment of the present invention.
Figure 4a is a graph showing the electrical conductivity of the particles according to the presence or absence of pulverization of the PPS of an embodiment of the present invention.
Figure 4b is a graph showing the electrical conductivity according to the GNP content of the composite according to an embodiment and a comparative example of the present invention.
Figure 4c is a graph showing the electrical conductivity according to the carbon content of the composite according to an embodiment of the present invention.
Figure 5a is a graph showing the bending strength of the particles according to the presence or absence of pulverization of PPS in an embodiment of the present invention.
Figure 5b is a graph showing the bending strength according to the GNP content of the composite according to an embodiment and a comparative example of the present invention.
6 is an SEM image of a composite according to an embodiment and a comparative example of the present invention.
7 is a graph showing the thermal conductivity according to the GNP content of the composite according to an embodiment and a comparative example of the present invention.

In the present specification, when a part "includes" a certain component, this means that other components may be further included rather than excluding other components unless otherwise stated. And the terminology used in this specification is for describing the embodiments, and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase.

According to one aspect, the present invention provides a thermoplastic resin comprising sulfide or fluorine; a thermoplastic resin-graphite nanoplatelet masterbatch formed of a thermoplastic resin containing sulfide or fluorine and graphite nanoplatelet (GNP); and graphite, wherein the masterbatch has a form in which a thermoplastic resin is combined on the surface of the graphite nanoplatelet, and the thermoplastic resin, the masterbatch, and graphite are laminated. A composite for a separator is provided.

In the present invention, any thermoplastic resin may be used as long as it has heat resistance, but may preferably include sulfide or fluorine. Such a thermoplastic resin may be included in the composite for a fuel cell separator of the present invention in order to secure excellent heat resistance, phosphoric acid resistance and physical properties to withstand a high temperature environment, and by including such a thermoplastic resin, excellent physical properties even in extreme environments such as high temperature and high phosphoric acid It is possible to form a complex capable of maintaining More preferably, the thermoplastic resin is poly(phenylene sulfide) (PPS), polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene (FEP), and polyfluorine It may be at least one selected from among alkoxyethylene copolymers (polyfluoroalkoxyethylene copolymers). In addition, in the present invention, the thermoplastic resin may be pulverized 1 to 3 times. Such a resin may be pulverized into fine particles having a diameter of 40 to 70 times smaller than the existing diameter, and may exhibit a diameter of 20 to 30 μm. In the present invention, the thermoplastic resin may be used in a pulverized form to improve homogeneity in the composite for fuel cell separator, and may be used after pulverization or pulverized.

Such a thermoplastic resin may be included as a component for forming a masterbatch, and may be included as a component of a composite for fuel cell separator itself. Depending on the carbon content in the composite for fuel cell separator, it may be included only as a configuration for forming a masterbatch, or may be further added after mixing the masterbatch and graphite.

The composite for a fuel cell separator of the present invention may include a masterbatch formed of a thermoplastic resin and graphite nanoplatelets. In this case, the masterbatch may be in a form in which a thermoplastic resin in the form of particles is combined on the surface of the graphite nanoplatelet in the form of a sheet. Preferably, the masterbatch is formed by ball milling the pulverized thermoplastic resin and pulverized graphite nanoplatelets, blending them under high temperature and high speed conditions, re pulverizing them, and then pulverizing them again in the presence of liquid nitrogen. can be In this case, the graphite nanoplatelet may be pulverized into fine particles having a diameter of 40 to 70 times smaller than the existing diameter, and may have a diameter of 50 to 80 μm. During the preparation of the masterbatch, exfoliation of the graphite nanoplatelets may occur, and by this exfoliation phenomenon, superior dispersibility may be exhibited compared to the conventional graphite nanoplatelets, resulting in excellent thermal and electrical properties.

In addition, the composite for a fuel cell separator of the present invention may include graphite, and preferably has a carbon content of 90 wt % or more.

The composite for a fuel cell separator of the present invention may include a powdered thermoplastic resin, a masterbatch, and graphite, and may be manufactured into a fuel cell separator by compression molding after mixing the powder. Such a composite may contain 70 to 90% by weight of carbon, preferably 80 to 90% by weight of carbon. When the carbon content exceeds 90 wt%, heat resistance and chemical resistance may be improved, but the moldability of the composite may be poor, making it difficult to form into a separator or other article, and the carbon content is 70 wt% If it is less than, it may be difficult to secure physical properties for use as a fuel cell separator.

Such a composite for a fuel cell separator may be in a form in which a thermoplastic resin, a master batch, and graphite are laminated, and the number of layers may be 50 to 100. More specifically, one sheet representing a form in which one or more particles selected from a master batch and a thermoplastic resin are combined on the surface of the graphite sheet may be laminated in multiple layers. In the composite for fuel cell separator of the present invention, which is formed through the process of mixing with graphite after forming the masterbatch, graphite nanoplatelets can be evenly dispersed in the thermoplastic resin serving as a matrix, and by high dispersibility Excellent physical properties can be exhibited.

According to another aspect, the present invention provides a first step of uniformly mixing a thermoplastic resin and graphite nanoplatelet (GNP) to form a mixture; a second step of stirring the mixture at a high temperature to form a masterbatch; and a third step of mixing the masterbatch and graphite through ball milling to form a reactant, wherein the thermoplastic resin includes sulfide or fluorine It provides a method for manufacturing a composite for a fuel cell separator characterized in that.

In the first step of the method for manufacturing the composite for fuel cell separator of the present invention, the thermoplastic resin and the graphite nanoplatelet may be pulverized and mixed uniformly, and preferably, the thermoplastic resin and the graphite nanoplatelet are pulverized after pulverizing the thermoplastic resin. can be milled or ball milled to form a mixture. In this case, the mixture may be in the form of a powder.

In the second step, a masterbatch may be formed by stirring the mixture at a high temperature of 290 to 320° C. at a rate of 50 to 55 N/m for 25 to 30 minutes, and preferably grinding 1 to 3 times after formation of the masterbatch. The process may be further performed to form a micronized masterbatch.

In the third step, the masterbatch and graphite may be ball milled at 200 to 210 rpm for 360 to 720 minutes to form a reactant, wherein the carbon content in the formed reactant may be 70 to 90 wt%. Preferably, the carbon content may be 80 to 90 wt%, and when the carbon content exceeds 90 wt%, heat resistance and chemical resistance may be improved, but the formability of the composite is poor, so a separator or other article It may be difficult to form into a fuel cell, and if the carbon content is less than 70% by weight, it may be difficult to secure physical properties for use as a fuel cell separator.

The process of molding the reactant thus formed using a molding plate may be further included, and the step of compressing the reactant to a pressure of 5 to 10 ton may be further included.

The description of the thermoplastic resin, graphite nanoplatelet, and graphite used in the method for manufacturing the composite for a fuel cell separator of the present invention is the same as or similar to that described above for the composite for a fuel cell separator of the present invention, and therefore will be omitted. .

The present invention will be described in more detail by the following examples. However, the following examples are intended to illustrate the present invention, and the scope of the present invention is not limited by the examples. It is provided to complete the disclosure of the present invention, and to completely inform those of ordinary skill in the art to which the present invention pertains to the scope of the invention.

<Example>

Example 1 - Masterbatch Preparation (MB)

Polyphenylene sulfide (poly(phenylene sulfide), PPS) powder was pulverized in the presence of liquid nitrogen using a porcelain mortar for use in the preparation of master batches. At this time, in order to facilitate the description in the specification, polyphenylline sulfide in the form of a pulverized powder is named _{PPS g.} 20 wt % of PPS _g and 80 wt % of graphite nanoplatelet (GNP) powder were mixed with a zirconia ball (diameter: 18 mm) at 210 rpm for 6 hours with a ball mill machine (LM-BD4530, LK Lab) A uniformly mixed fine PPS _g /GNP powder was obtained by mixing. Afterwards, the fine powder was stirred at 320° C. at a speed of 50 N/m for 30 minutes, and the stirred powder (masterbatch, MB) was ground using a grinder, and finally pulverized by pulverizing in the presence of liquid nitrogen for 40 minutes. A powdered masterbatch (MB _g ) was prepared.

Example 2 - Preparation of composite for fuel cell separator (PPS) _g /MB _g /graph)

In order to prepare a composite for a fuel cell separator, the total carbon content in the composite by adding the content of GNP in the masterbatch according to Example 1 to the content of graphite included in the composite was fixed to 80% by weight. In addition, GNP in the masterbatch was included up to 5% by weight. In this case, graphite was used in the form of a plate-like powder having a particle diameter of 500 μm, and the content of carbon and oxygen was 98.19% and 1.81%, respectively, and graphite having high purity was used. _{MB g} and PPS _g prepared according to Example 1, and graphite powder were mixed with a ball mill machine (LM-BD4530, LK Lab) with a zirconia ball (diameter: 18 mm) for 6 hours at 210 rpm according to the weight, respectively to prepare a mixed powder, and put 80 g of the mixed powder into a square alloy platen of 6.0 (width) × 6.0 (length) × 3.5 (thickness) cm ³ size, and using a compressor (QM900M, QMESYS) at 2000 psi pressure at 300°C compressed for 1 hour. Thereafter, the temperature was set to -7°C per minute, and the compressed separator was cooled to 70°C to finally _{prepare a composite for fuel cell separator (PPS g} /MB _g /graphite). The manufacturing process of the composite according to Examples 1 and 2 is shown in FIG. 1 .

A composite in which the total carbon content in the composite was fixed to 80 wt% was prepared according to Examples 1 and 2, and a total of 5 types of composites shown in Table 1 below were prepared according to the weight of GNP in the masterbatch.

Example 3 - PPS _g /graphite composite production (carbon content - 80% by weight)

_{A PPS g} /graphite composite _{containing 14.22 g of PPS g} and 56.86 g of graphite was prepared through a hot forming process using the _{pulverized powdered PPS g} prepared according to Example 1 and graphite. .

Example 4 - PPS _g /graphite composite production (carbon content - 85 wt%)

_{A PPS g} /graphite composite _{containing 10.94 g of PPS g} and 62.01 g of graphite was prepared through a hot forming process using the _{pulverized powdered PPS g} prepared according to Example 1 and graphite. .

Example 5 - PPS _g /graphite composite production (carbon content - 90 wt%)

_{A PPS g} /graphite composite _{containing 7.49 g of PPS g} and 67.43 g of graphite was prepared through a hot forming process using the _{pulverized powdered PPS g} prepared according to Example 1 and graphite. .

Example 6 - PPS _g /graphite composite production (carbon content - 95 wt%)

_{A PPS g} /graphite composite _{containing 3.85 g of PPS g} and 73.15 g of graphite was prepared through a hot forming process using the _{pulverized powdered PPS g} prepared according to Example 1 and graphite. .

Comparative Example 1 - PPS _g /GNP/graphite complex manufacturing

Unlike the above example, a composite was prepared using graphite nanoplatelet (GNP) powder without the preparation of the masterbatch. GNP, PPS _g , and graphite powder were mixed with a zirconia ball (diameter: 18 mm) at 210 rpm for 6 hours with a ball mill machine (LM-BD4530, LK Lab) to prepare a mixed powder, 6.0 (width) × 6.0 (length) × 3.5 (thickness) cm ³ Put 80 g of the mixed powder into a square alloy platen of the size, and compressed using a compressor (QM900M, QMESYS) at 2000 psi pressure at 300 ℃ for 1 hour. Thereafter, the temperature was set to -7°C per minute, and the compressed separator was cooled to 70°C to finally _{prepare a PPS g} /GNP/graphite composite.

According to Comparative Example 1, a composite in which the total carbon content in the composite was fixed to 80% by weight was prepared, and a total of 5 types of composites shown in Table 2 below were prepared according to the weight of GNP.

_{The manufacturing process of the PPS g} /MB _g /graphite composite according to Examples 1 to 2 and the manufacturing process and the complex formation model _{of the PPS g} /GNP/graphite composite according to Comparative Example 1 are shown in FIG. 2 .

Comparative Example 2 - Preparation of PPS/graphite composite (carbon content - 80 wt%)

14.22 g of PPS through a hot forming process using unpulverized pure PPS and graphite and 56.86 g of graphite to prepare a PPS/graphite composite.

<Experimental example>

Experimental Example 1 - Particle Size Measurement

A particle size analyzer (PSA; Mastersizer 3000, Malvern Panalytical, UK) was used to compare and analyze the particle size according to the presence or absence of pulverization of the PPS, and the size of the powder in the ethanol phase as a dispersant was measured according to the Mie scattering method.

Experimental Example 2 - Electrical conductivity measurement

In order to compare and analyze the electrical conductivity of the composite according to Example 3 and Comparative Example 2, the electrical conductivity of the composite according to Example 2 and Comparative Example 1, and the electrical conductivity of Examples 4 to 7, a constant of 0.85 A The electrical conductivity in the plane direction in the current was 10 (width) × 10 (thickness) × 50 (length) mm ³ samples, and the electrical conductivity in the thickness direction was 10 (width) × 10 (thickness) × 10 (length) ) The electrical conductivity was measured using a sample having a size of ^{mm 3 .}

Experimental Example 3 - Intensity Measurement

A universal testing machine (ST-1001, Mouser Electronics) was used to compare and analyze the bending strength of the composites according to Example 3 and Comparative Example 2 and the bending strength of the composites according to Example 2 and Comparative Example 1, and the strength was ASTM Measurements were made according to D790 by applying a 100-kgf load and a tip speed of 10 mm·min-1. The data were measured 5 times and extracted by averaging the standard deviation.

Experimental Example 4 - SEM image measurement

After the sample to the embodiment of the masterbatch prepared according to the first and to the PPS _g and correlates milled PPS _g / form of GNP simply viewed without mixing a GNP a Pt-coated electron microscope (SEM; S-4300, Hitachi , Japan) to confirm the cross-section of the inner surface of the sample.

Experimental Example 5 - Thermal conductivity measurement

A thermal conductivity analyzer (LFA 457 MicroFlash, NETZSCH, Germany) was used to comparatively analyze the thermal conductivity of the composite according to Example 2 and Comparative Example 1, and a disk sample having a thickness of 2 mm and a diameter of 18 mm prepared according to ASTM E1461 was obtained. The degree of heat diffusion was measured through laser flash analysis. Then, the thermal conductivity was calculated using the equation λ=α· C _{p ·ρ.} At this time, λ, α, C _p , ρ are respectively thermal conductivity [W·(m·K) ^-1 ], thermal diffusivity [m ² ·s ^-1 ], specific heat [J·(kg·K) ^-1 ], and density [ kg·m ^-3 ].

<Results and evaluation>

Result 1 - Result of particle size measurement

The particle size according to the presence or absence of pulverization (PPS or PPS _g ) of the PPS used in the Examples and Comparative Examples was comparatively analyzed according to Experimental Example 1, and the results are shown in FIG. 3 .

The graph of FIG. 3 is a graph showing the particle size distribution of PPS before and after pulverization. While unprocessed pure PPS exhibits a particle size of 300 μm or more and the distribution appears widely, the pulverized according to an embodiment of the present invention In _{the case of PPS g} , it was confirmed that particles having an average size of 30 μm appeared in a narrow range of distribution.

In the case of general PPS, as shown in FIG. 3, the particle size is not uniform and the size itself is large, so it is difficult to mix with graphite, but PPS _g has a fine and uniform particle size, so that the graphite particles are evenly covered to form a composite. Increasing the uniformity of the composite in this way can improve the mechanical properties, electrical properties and thermal conductivity of the composite itself.

Result 2 - Electrical conductivity measurement result

The electrical conductivity of the composites according to Examples and Comparative Examples was comparatively analyzed according to Experimental Example 2, and the results are shown in FIGS. 4A to 4C.

Referring to FIG. 4a showing the results of electrical conductivity in the plane direction and thickness direction of the composite according to the pulverization of PPS, the PPS _g / graphite composite according to Example 3 had electrical conductivity in the plane direction and electrical conductivity in the thickness direction of 625 S, respectively. ㆍcm- ¹ and 19 It was shown as S·cm- ¹ , and the PPS/graphite composite according to Comparative Example 2 was 523 S·cm- ¹ and 16, respectively. It was shown as S·cm- ^1. This means that the resin-graphite composite prepared without grinding or pulverization can exhibit more electrical defects and low electrical conductivity, and when pulverizing and refining is additionally performed, higher electrical conductivity can be secured and electrical defects can be lowered. meaning the result.

Looking at FIG. 4b showing the electrical conductivity results according to the weight % of GNP in the composite according to Example 2 and Comparative Example 1, in the case of the PPS _g /MB _g /graphite composite according to the Example (black graph), the GNP in the composite was As it increased, the electrical conductivity in the plane direction of the composite also increased, showing the maximum electrical conductivity value (1349 S·cm- ¹ _{) when the weight % of GNP was 5. In the case of the PPS g} /GNP/graphite composite according to the comparative example (blue color) Graph) also showed an increase in electrical conductivity as the GNP in the complex increased, showing the maximum electrical conductivity value (824 S·cm- ¹ ) when the GNP weight % was 5. In the case of electrical conductivity in the thickness direction, similarly, as the weight % of GNP increased, all electrical conductivity values increased, but the PPS _g /MB _g /graphite composite showed a maximum of 54 S·cm- ¹ , and PPS _g / In the case of the GNP/graphite composite, it was found that the maximum was 29 S·cm- ¹ , indicating that the composite including the masterbatch exhibited better electrical conductivity. Accordingly, it was confirmed that the GNPs were well dispersed in the complex prepared by forming the masterbatch and exhibited a strong synergistic effect such as electrical conductivity.

_{Referring to FIG. 4c showing the electrical conductivity according to the carbon content of the PPS g} / graphite composites of Examples 4 to 7, it was confirmed that the electrical conductivity increased as the carbon content increased in both the plane direction and the thickness direction. ^{However, in order to show the maximum electrical conductivity of 1349 S·cm-1} in the plane direction and the maximum value of 54 S·cm- ¹ of electrical conductivity in the thickness direction confirmed in FIG. 4b, the composite should contain about 93 to 96% by weight of carbon. Could know. Such a large amount of graphite is difficult to process and there is a concern that mechanical properties may be deteriorated.

Therefore, when a small amount of GNP is added as a composite in the form of a masterbatch, high electrical conductivity can be exhibited only with graphite of a weight that can secure excellent processability and mechanical properties, so that strict electrical and mechanical properties are required. It is expected that the composite according to the present invention can be utilized as a separator.

Result 3 - Intensity Measurement Results

The bending strength of the composites according to Examples and Comparative Examples was comparatively analyzed according to Experimental Example 3, and the results are shown in FIGS. 5A and 5B.

Referring to FIG. 5a showing the bending strength of the composite according to the pulverization of PPS, the composite obtained by pulverizing PSS (Example 3) had a strength of 32 MPa, which was 3 MPa higher than that of the composite without pulverization of PSS (Comparative Example 2). This result means that higher strength can be secured when PPS is pulverized and used.

In addition, _{looking at FIG. 5b showing the bending strength of the PPS g} /MB _g /graphite composite and the PPS _g /GNP/graphite composite, it was confirmed that the difference in strength did not appear significantly. In all composites, strength higher than the basic strength required to be used as a separator for fuel cells was secured, and even if graphite was partially replaced with GNP to improve electrical and thermal properties, the existing excellent strength could still be secured. is a result that means

Result 4 - SEM image measurement result

In order to compare and analyze the shape of the masterbatch prepared according to Example 1 _{and PPS g} /GNP simply ball-milled without mixing _{the PPS g} and GNP, the SEM image of the cross-section was measured according to Experimental Example 4, and the result is shown in FIG. 6 .

Looking at the cross section of the masterbatch on the left side of FIG. 6 , it was confirmed that _{well-dispersed GNPs protrude from the MB g surface.} It was found that the manufacturing method according to the embodiment of the present invention generated sufficient shear stress to disperse the GNPs, and through this, the masterbatch prepared according to the embodiment of the present invention secured uniformity.

On the other hand, looking at the cross-section of the composite on the right side of FIG. 6 , it was confirmed that a lump having a diameter greater than 1 mm was formed. This is due to the π-π interaction, and dispersion was not performed properly, and it is thought that the uniformity and physical properties of the complex may be deteriorated as a result. Therefore, in the present invention, a composite for a fuel cell separator was prepared using PPS and graphite as secondary fillers using _{MB g powder pulverized from the masterbatch.}

Result 5 - Thermal conductivity measurement result

The thermal conductivity of the composites according to Example 2 and Comparative Example 1 was comparatively analyzed according to Experimental Example 5, and the results are shown in FIG. 7 .

7 shows the thickness direction thermal conductivity of the composite according to the GNP weight%. The PPS _g /MB _g /graphite composite and the PPS _g /GNP/graphite composite had thermal conductivity of ^{144 W·(m·K) - 1} and 78 W·(m·K) ^-1 when the GNP content was 4 wt%, respectively. _{is shown, and it was confirmed that the thermal conductivity of the PPS g} /MB _g /graphite composite was increased by about 140% compared to when GNP was not included. On the other hand, it was found that only about 30% of the _{PPS g} / GNP / graphite complex was increased, indicating that GNP was well dispersed in the PPS substrate _{of the PPS g} / MB _{g / graphite complex prepared according to an embodiment of the present invention.} Could know.

Claims (7)

a pulverized thermoplastic resin having a diameter of 20 to 30 μm containing sulfide or fluorine;
a thermoplastic resin-graphite nanoplatelet masterbatch formed of separately pulverized thermoplastic resin and graphite nanoplatelet (GNP) having the same diameter as the thermoplastic resin; and
Graphite (graphite); including;
The masterbatch is in a form in which graphite nanoplatelets are dispersed in the thermoplastic resin,
The graphite nanoplatelet is a composite for a fuel cell separator, characterized in that it contains 0.71 to 5% by weight based on 100% by weight of the masterbatch.
The method of claim 1,
The thermoplastic resin is poly(phenylene sulfide) (PPS), polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene (FEP), and polyfluoroalkoxyethylene copolymer. A composite for a fuel cell separator, characterized in that at least one selected from polyfluoroalkoxyethylene copolymers.
The method of claim 1,
The composite for a fuel cell separator, characterized in that the thermoplastic resin, the masterbatch, and the graphite are in the form of a powder.
The method of claim 1,
The composite is a composite for a fuel cell separator, characterized in that it contains 70 to 90% by weight of carbon.
A first step of uniformly mixing a pulverized thermoplastic resin having a diameter of 20 to 30 μm including sulfide or fluorine and graphite nanoplatelet (GNP) to form a mixture;
a second step of stirring the mixture at a high temperature to form a masterbatch; and
A third step of forming a reactant by mixing the master batch, a separately pulverized thermoplastic resin having the same diameter as the thermoplastic resin and graphite, and
The masterbatch is in a form in which graphite nanoplatelets are dispersed in the thermoplastic resin,
The method for producing a composite for a fuel cell separator, characterized in that the graphite nanoplatelet contains 0.71 to 5% by weight based on 100% by weight of the masterbatch.
6. The method of claim 5,
The first step is a method of manufacturing a composite for a fuel cell separator, characterized in that the thermoplastic resin and the graphite nanoplatelet are pulverized and uniformly mixed.
6. The method of claim 5,
The method of manufacturing a composite for a fuel cell separator, characterized in that it further comprises the step of compressing the reactant.

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