WO2019194112A1

WO2019194112A1 - Metal-carbon laminate precursor, and method for manufacturing metal-carbon laminate precursor

Info

Publication number: WO2019194112A1
Application number: PCT/JP2019/014419
Authority: WO
Inventors: 村上　信吉; 中塚　淳; 石井　守; 徹稲熊; 孝飯島; 禰宜　教之; 岡田　克己
Original assignee: 日鉄ケミカル＆マテリアル株式会社
Priority date: 2018-04-02
Filing date: 2019-04-01
Publication date: 2019-10-10
Also published as: JPWO2019194112A1; TW201944635A; JP7258014B2

Abstract

The present invention addresses the problem of providing: a metal-carbon laminate precursor with which fine grooves such as gas flow paths in fuel cell separators can be formed with high precision by a heating and pressing treatment, and the electrical resistance across a metal-carbon laminate member in the lamination direction after the heating and pressing treatment can be kept small; and a method for manufacturing the metal-carbon laminate precursor. This metal-carbon laminate precursor (X) has a carbon-resin mixed layer (2) laminated on at least one surface of a metal substrate (1) made of a metal thin plate, wherein the carbon-resin mixed layer (2) contains: a mixed carbon powder of graphite powder and carbon black; and a binder resin made of a thermosetting resin. The carbon-resin mixed layer (2) has a porosity of 40-80 vol%, and a degree of curing of 10-50% as measured by a differential scanning calorimeter. The binder resin in the carbon-resin mixed layer (2) can be cured by a heating and pressing treatment to obtain a metal-carbon laminate member having a carbon layer laminated on the metal substrate (1).

Description

Metal carbon laminate precursor and method for producing metal carbon laminate precursor

The present invention relates to a metal carbon laminate precursor capable of obtaining a metal carbon laminate member of a metal base material and a carbon layer by heat and pressure treatment, and a method for producing the same, and is not particularly limited. It is related with the metal carbon lamination | stacking precursor suitable for obtaining, and its manufacturing method.

In recent years, polymer electrolyte fuel cells that can operate at a low temperature of 100 ° C. or less have attracted attention, and are being developed and put into practical use as driving power sources for vehicles and stationary power generators. A general polymer electrolyte fuel cell includes a membrane electrode assembly (MEA) having a catalyst layer serving as an anode and a cathode on both sides of a proton conductive electrolyte membrane, and a membrane electrode assembly (MEA). A structure composed of a gas diffusion layer disposed outside the catalyst layer and a separator disposed outside the gas diffusion layer sandwiching the membrane electrode assembly is used as a basic structure (unit cell). Are stacked by stacking as many unit cells as necessary to achieve the following output.

In such a unit cell of the polymer electrolyte fuel cell, from the gas flow path of the separator respectively disposed on the anode side and the cathode side, an oxidizing gas such as oxygen or air is provided on the cathode side, A fuel gas such as hydrogen is supplied to the anode side, and the supplied oxidizing gas and fuel gas (hereinafter sometimes referred to as “reactive gas”) are respectively supplied to the catalyst layer via the gas diffusion layer. The work is taken out in the form of electric power by utilizing the energy difference (potential difference) between the chemical reaction occurring in the anode catalyst layer and the chemical reaction occurring in the cathode catalyst layer. For example, when hydrogen gas is used as the fuel gas and oxygen gas is used as the oxidizing gas, a chemical reaction that occurs in the catalyst layer of the anode [oxidation reaction: H ₂ → 2H ⁺ + 2e ⁻ (E ₀ = 0V) ] And the chemical reaction [reduction reaction: O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (E ₀ = 1.23 V)] occurring in the cathode catalyst layer is taken out as work.

Therefore, the separator constituting the unit cell of the polymer electrolyte fuel cell not only has a function of partitioning each unit cell, but also supplies a flow path for supplying an oxidizing gas to the catalyst layer of the MEA and a fuel gas to the catalyst layer. A function to supply these reaction gases uniformly in a state of being completely separated to the catalyst layer by forming a gas flow path, a function of collecting current (electron) generated in the catalyst layer of each unit cell, and MEA This separator also has a heat dissipation function to release the generated heat to the outside. Therefore, this separator is required to have gas impermeability that does not allow reaction gas to permeate and excellent conductivity for current collection. High corrosion resistance is required for the environment to be a strong acid atmosphere.

As a separator for a polymer electrolyte fuel cell, a carbon separator that has an excellent electrical conductivity and is advantageous for a current collecting function has been used. However, since it is poor in flexibility and flexibility and is easy to break, stainless steel is used. Replacement with metal separators such as steel and titanium is under consideration. However, for example, a stainless steel has a problem that a passive film is formed, resulting in an increase in electrical resistance. In general, a metal separator has a problem that it is easily corroded in a use environment of a fuel cell. Furthermore, a metal separator is not suitable for forming a fine groove (concave portion) forming a flow path such as a gas flow path for flowing a reaction gas or a refrigerant flow path for flowing a refrigerant with high accuracy.

On the other hand, a composite type separator has been proposed in which a carbon layer formed by including graphite powder and a binder resin is provided on a metal substrate made of a thin metal plate (see, for example, Patent Documents 1 and 2). Such a composite separator is not only excellent in gas impermeability and conductivity, but also excellent in flexibility and corrosion resistance, and is considered suitable as a separator for a polymer electrolyte fuel cell. Further, when the carbon layer is obtained, grooves can be simultaneously formed in the carbon layer by compression molding a mixed material containing graphite powder and a binder resin using a predetermined mold. However, since resin flow is required for precise groove formation, there is a problem that a long time is required for molding. In the first place, there is also a problem that the corners of the fine groove shape are difficult to reproduce accurately because the mixed material is not sufficiently filled with the mold shape for groove formation.

JP 2016-110724 A JP 2017-71218 A

Among the polymer electrolyte fuel cells, it is practically important to reduce the stack size especially in the fuel cell for automobiles. Specifically, studies are being made to reduce the total thickness of the separator to 1 mm or less. In this case, the groove shape for gas flow is about 0.1 mm to 0.5 mm in both the groove depth and the channel width, and therefore, the processing accuracy is required to be at least about 0.01 mm. In order to meet such demands, in the case of composite separators, it is necessary to reduce the size of the graphite powder that forms the carbon layer. However, if the particle size is reduced, the fluidity of the material during heating and pressing decreases. It becomes difficult to satisfy the accuracy of 0.01 mm. Further, when the particle diameter is reduced, the number of contact points between particles having a large contact resistance increases, and the electrical resistance penetrating through the carbon layer molded with the binder resin increases. In this way, when a fine groove forming a flow path such as a gas flow path or a refrigerant flow path is obtained by compression molding (heating and pressurizing treatment heated under pressure), a processing accuracy of about 0.01 mm is actually maintained. However, it is extremely difficult to ensure high electrical conductivity.

Accordingly, the present inventors have intensively studied to solve the above problems in a composite fuel cell separator having a carbon layer on a metal substrate, and as a result, a thermosetting resin as a binder resin for forming the carbon layer. And pre-curing the thermosetting resin to prepare a separator precursor having a porous carbon resin mixed layer having a predetermined degree of curing and a predetermined porosity, and combining the carbon It was found that by adding carbon black to the graphite powder forming the resin mixed layer, it was possible to improve the conductivity at the same time while ensuring the fluidity at the time of compression molding, and completed the present invention.
As will be described later, the metal carbon laminate precursor (herein, the separator precursor) in the present invention can be heated and pressurized to obtain a metal carbon laminate member (herein referred to as a fuel cell separator). it can. In other words, the degree of curing of the thermosetting resin in the metal carbon laminate precursor is such that the curing reaction does not proceed as compared with the thermosetting resin when finally used as the metal carbon laminate member. Therefore, when expressing these differences, in this specification, pre-curing (in the case of a metal carbon laminated precursor) and main curing (in the case of a metal carbon laminated member) are properly used.

Therefore, an object of the present invention is to form a fine groove shape such as a gas flow path in a fuel cell separator with high accuracy by heating and pressurizing treatment, and furthermore, metal carbon lamination after the heating and pressurizing treatment. An object of the present invention is to provide a metal carbon lamination precursor capable of keeping the through electric resistance in the lamination direction of members small.
Another object of the present invention is to provide a method for producing the metal carbon laminate precursor.

In addition, the metal carbon lamination | stacking precursor which concerns on this invention can be used also for uses other than the separator for fuel cells using the above-mentioned highly accurate moldability and thermal conductivity. For example, in small electronic devices such as smartphones, tablets, notebook computers, etc., in order to release heat generated from LSI chips such as CPU, driver IC, memory, etc., the heat dissipation effect is achieved by sandwiching between these heating elements and heat dissipation components. When the heat dissipation sheet to be used is used, the metal carbon laminate precursor of the present invention can be finely shaped by heat and pressure treatment, and also has excellent heat conductivity in the pressurizing direction. It is also suitable as a metal carbon laminate precursor for a heat dissipation sheet.

That is, the gist of the present invention is as follows.
(1) A metal carbon laminate precursor capable of obtaining a metal carbon laminate member of a metal substrate and a carbon layer by a heating and pressurizing treatment heated under pressure,
A carbon resin mixed layer containing a mixed carbon powder of graphite powder and carbon black and a binder resin made of a thermosetting resin is laminated on at least one surface of a metal base made of a thin metal plate, and the carbon resin mixed layer is The porosity is 40 to 80% by volume, the degree of cure measured by a differential scanning calorimeter is 10 to 50%, and the binder resin in the carbon resin mixed layer is fully cured by heat and pressure treatment, A metal carbon laminate precursor characterized in that a metal carbon laminate member in which a carbon layer is laminated on a metal substrate can be obtained.
(2) The mass ratio of the binder resin and the mixed carbon powder in the carbon resin mixed layer is 5:95 to 40:60, and the mass ratio of the graphite powder to the carbon black in the mixed carbon powder is 99: 1. The metal-carbon laminated precursor according to (1), which is 90:10.
(3) The metal according to (1) or (2), wherein the carbon black is one or more selected from the group consisting of porous carbon black, acetylene black, and highly crystalline carbon black. Carbon laminate precursor.
(4) The metal carbon multilayer precursor according to any one of (1) to (3), wherein a crystallite size Lc in the C-axis direction by powder X-ray diffraction of the carbon black is 2 nm or more and 10 nm or less.
(5) In the pore volume measurement by the mercury intrusion method, the carbon black has a mercury intrusion amount V _Hg having a pore diameter of 10 nm to 500 nm of 1.5 mL / g or more and 3.0 mL / g or less (1) The metal carbon laminate precursor according to any one of (4) to (4).
(6) The metal carbon laminate precursor according to any one of (1) to (5), wherein the metal carbon laminate member is a fuel cell separator.

(7) A method for producing a metal carbon laminate precursor capable of obtaining a metal carbon laminate member of a metal substrate and a carbon layer by a heat and pressure treatment heated under pressure,
A mixed carbon powder of graphite powder and carbon black, a binder resin made of a thermosetting resin, and a slurry-like mixed material containing a solvent are arranged on the surface of a metal substrate made of a metal thin plate, heat-treated, and the mixed material By pre-curing the binder resin therein, a carbon resin mixed layer having a porosity of 40 to 80% by volume and a curing degree measured by a differential scanning calorimeter of 10 to 50% is formed of a metal thin plate. A method for producing a metal carbon lamination precursor, comprising laminating at least one side of a substrate.
(8) A method for producing a metal carbon laminate precursor capable of obtaining a metal carbon laminate member of a metal base material and a carbon layer by a heat and pressure treatment heated under pressure,
A first heat treatment for forming a sheet body from a mixed powder of graphite powder and carbon black and a powdered mixed material containing a binder resin made of a thermosetting resin, and the sheet body is made of a metal sheet. 2nd heat treatment performed on the surface of the base material, and by pre-curing the binder resin in the mixed material, the porosity is 40-80% by volume and measured by a differential scanning calorimeter A method for producing a metal carbon laminate precursor, comprising: laminating a carbon resin mixed layer having a degree of curing of 10 to 50% on at least one surface of a metal substrate made of a metal thin plate.
(9) The mass ratio of the binder resin and the mixed carbon powder in the mixed material is 5:95 to 40:60, and the mass ratio of the graphite powder to the carbon black in the mixed carbon powder is 99: 1 to 90. : The manufacturing method of the metal carbon lamination | stacking precursor as described in (7) or (8) which is 10.
(10) In any one of (7) to (9), the carbon black is one or more selected from the group consisting of porous carbon black, acetylene black, and highly crystalline carbon black The manufacturing method of the metal carbon lamination | stacking precursor of description.
(11) The method for producing a metal carbon laminated precursor according to any one of (7) to (10), wherein a crystallite size Lc in the C-axis direction by powder X-ray diffraction of the carbon black is 2 nm or more and 10 nm or less.
(12) In the pore volume measurement by the mercury intrusion method, the carbon black has a mercury intrusion amount V _Hg having a pore diameter of 10 nm to 500 nm of 1.5 mL / g or more and 3.0 mL / g or less (7) A method for producing a metal carbon laminate precursor according to any one of (11) to (11).
(13) The method for producing a metal carbon laminate precursor according to any one of (7) to (12), wherein the metal carbon laminate member is a fuel cell separator.

According to the metal carbon laminate precursor according to the present invention, a fine groove shape can be formed with high accuracy by heat and pressure treatment, and the through-electricity in the lamination direction of the metal carbon laminate member after the heat and pressure treatment is achieved. Resistance can be kept small. Therefore, the metal carbon laminate precursor of the present invention is used, for example, to obtain a composite type fuel cell separator provided with a carbon layer formed on a metal substrate, including graphite powder, carbon black, and a binder resin. Preferably used. That is, since the processing accuracy of the gas flow path is high, the pressure loss can be reduced, and the voltage drop due to the ohmic resistance of the separator during power generation can be reduced.

The metal carbon laminate precursor of the present invention can also be used in applications other than fuel cell separators. For example, in small electronic devices such as smartphones and tablets, heat generated from chips such as CPUs and driver ICs. It is also suitable for obtaining a heat radiating sheet for releasing heat. In other words, the metal carbon laminate precursor of the present invention can be finely shaped by heat and pressure treatment, has excellent shape followability, and has excellent heat conductivity in the pressing direction. The heat dissipation effect can be further enhanced when the heat dissipation sheet is sandwiched between a heat generating element such as that described above and a heat dissipation component such as a metal casing.

FIG. 1 is a schematic cross-sectional view for explaining a metal carbon laminate precursor according to the present invention. FIG. 2 is a schematic cross-sectional view for explaining a metal carbon laminated member Y obtained by subjecting the metal carbon laminated precursor of the present invention to heat and pressure treatment. FIG. 3 is a partial cross-sectional schematic view for explaining the state of the carbon resin mixed layer in the metal carbon laminate precursor of the present invention. FIG. 4 is a schematic view for explaining a state in which a metal carbon laminated member is manufactured by subjecting the metal carbon laminated precursor of the present invention to a heat and pressure treatment. FIG. 5 is a schematic plan view showing a fuel cell separator. FIG. 6 is a schematic diagram for explaining the test mold used in the groove shape evaluation by mold molding in the example, and FIG. 6A is a metal obtained by heating and pressurizing with the test mold. The state of the carbon layer of the carbon laminated member is shown, and FIG. 6B is an enlarged view of a part thereof.

The present invention will be described in detail below.
As shown in FIG. 1, the metal carbon laminate precursor in the present invention is a binder resin made of a mixed carbon powder of graphite powder and carbon black and a thermosetting resin on at least one surface of a metal substrate 1 made of a thin metal plate. The carbon resin mixed layer 2 containing is laminated, and the metal of the metal substrate 1 and the carbon layer 11 as shown in FIG. 2 is obtained by heat and pressure treatment (hot pressing) using a mold or the like. The carbon laminated member Y can be obtained. FIG. 1 is an example of a metal carbon lamination precursor X provided with a carbon resin mixed layer 2 on both surfaces of the metal substrate 1, and FIG. 2 shows such a metal carbon lamination precursor X heated and pressurized. It is an example of the metal carbon laminated member Y obtained by doing.

Here, one of the technical points that are essentially important for solving the problems in the present invention described above is to follow the mold accuracy of the order of 0.01 mm during the heating and pressurizing process. Within the elapsed time of the heat and pressure treatment, after the binder resin and graphite powder constituting the carbon resin mixed layer flow and accurately follow the shape of the mold, the shape is fixed by curing the binder resin. I am doing so. That is, the device for securing the fluidity is the technical skeleton of the present invention, and at least (i) optimization of the porosity of the metal carbon laminate precursor as a preform, (ii) the metal carbon laminate The optimization of the degree of curing of the precursor (specifically, the degree of curing of the thermosetting resin used as the binder resin) and (iii) the blending of carbon black are simultaneously satisfied. As a result, the present inventors have found that the fluidity capable of achieving the mold accuracy as described above can be secured and the electrical resistance of the obtained metal carbon laminated member can be reduced, thereby completing the present invention.

Specifically, first, the carbon resin mixed layer in the metal carbon laminate precursor X of the present invention has a porosity of 40 to 80% by volume, preferably 50 to 70% by volume, and is measured by a differential scanning calorimeter. The degree of cure (hereinafter simply referred to as the degree of cure) is 10 to 50%, preferably 20 to 40%. When the porosity is less than 40% by volume, for example, when the metal carbon laminated member Y as shown in FIG. 2 is used as a separator of a fuel cell, the mold of the carbon resin mixed layer in the heat and pressure treatment The followability becomes insufficient, and the mixed carbon powder forming the carbon resin mixed layer and the binder resin are not sufficiently filled with the mold shape for forming the groove forming the flow path, and the fine groove shape, particularly There is a possibility that the corner of the groove may not be accurately reproduced. If the corner of the groove is rounded, the contact area that comes into contact with the MEA is reduced, and the power generation efficiency is reduced. On the other hand, if the porosity exceeds 80% by volume, the strength of the carbon resin mixed layer is insufficient, causing problems in durability and handling properties, and insufficient conductivity due to low density. There is a risk of becoming.

As for the degree of cure of the carbon resin mixed layer, if the degree of cure is less than 10%, the binder resin is not sufficiently pre-cured, the strength of the carbon resin mixed layer is insufficient, and the durability during handling is a problem. There is a risk of becoming. On the other hand, if the degree of cure exceeds 50%, the pre-curing of the binder resin proceeds too much, and the mold followability of the carbon resin mixed layer in the case of obtaining a fuel cell separator becomes insufficient, and the heat and pressure treatment The reproducibility of the fine groove shape due to is inferior.

Here, the porosity in the present invention is measured by the following method. That is, for example, the volume of the carbon resin mixed layer is quantified by forming a carbon resin mixed layer on one side of the metal substrate, cutting it into a 1 cm square, and measuring its thickness. The mercury intrusion measurement was performed using the flake as a sample, and the amount of mercury intrusion (integrated value) (unit: mL) when injecting up to 400 MPa was defined as the void of the carbon resin mixed layer, and the volume of the carbon resin mixed layer described above was defined. This void ratio is defined as the void ratio.

The degree of cure indicates the ratio of functional groups that have already reacted (crosslinked) among all functional groups of the thermosetting resin. In the present invention, differential scanning calorimetry (DSC) is used for specific measurement. The ratio of the amount of generated heat after a predetermined process to the total amount of heat of reaction of the thermosetting resin used for the binder resin is expressed in terms of 100 fractions. In detail, it can obtain | require by the method described in the Example mentioned later.

Regarding the binder resin forming the carbon resin mixed layer, for example, assuming that the finally obtained metal carbon laminated member Y is used as a separator for a fuel cell, the fuel cell is mounted on an automobile or the like. A thermosetting resin is used in consideration of durability in the operating environment. There is no restriction | limiting in particular as this thermosetting resin, For example, a phenol resin, an epoxy resin, an unsaturated polyester resin etc. can be mentioned, These 1 type (s) or 2 or more types can be used. Among them, it is preferable to use a resol type phenol resin or an epoxy resin excellent in durability. Further, for the purpose of shortening the curing time and increasing the production efficiency per hour, it is possible to apply an existing technique for shortening the curing time of the resin. For example, a curing accelerator may be mixed with a resin and used in the present invention.

In addition, as the binder resin of the present invention, when obtaining the metal carbon laminate precursor X, a powdery one at room temperature or a liquid one may be used. In the case of using a powder, since it does not deteriorate the resin flow in the heat and pressure treatment for obtaining the metal carbon laminated member or suppress the aggregation of the resin particles, It is preferable to use a powder smaller than the powder. Specifically, the average particle diameter of the resin powder is preferably in the range of 1/100 to 5 times the average particle diameter of the graphite powder. 1/100 to 3 times is preferable. On the other hand, the absolute average particle diameter of the resin powder is preferably about 1 to 200 μm, and preferably about 1 to 100 μm.

Next, with respect to the mixed carbon powder forming the carbon resin mixed layer, in the present invention, carbon black is blended as described above, and a mixture of graphite powder and carbon black is used. That is, in order to achieve both the fluidity during the heating and pressurizing treatment and the reduction of the electrical resistance when the metal carbon laminated member is used, it is essentially important to mix the carbon black with the graphite powder in solving the problems of the present invention. One of the technologies. Examples of the carbon black include porous carbon black, acetylene black, highly crystalline carbon black, and oil furnace black. Preferably, the carbon black is porous carbon black, acetylene black, or highly crystalline carbon black. There may be, and you may make it use these 1 type, or 2 or more types. With respect to these carbon blacks, in the present invention, for the purpose of improving the fluidity as described above and simultaneously reducing the electric resistance after molding, (i) the particle diameter of the carbon black, (b) the dendritic structure, and (C) Crystallinity was examined.

And it discovered that the effect of this invention could be improved further by aiming at these optimization. That is, the inventors considered that it is important to reduce the affinity of carbon black for resin and increase the fluidity, and paid attention to the crystallinity of carbon black as a physical property of carbon black that controls the affinity. As a result, by improving the crystallinity and reducing the surface functional groups, the affinity with the binder resin is reduced, the fluidity during the heat and pressure treatment can be increased to the maximum, and it is more effective in improving the processing accuracy of the groove shape. I found out. Here, the crystallinity of carbon black is the size of the graphite crystallite by X-ray diffraction, specifically, the crystallite size in the stacking direction of the hexagonal network surface of graphite is optimal as a physical property for controlling fluidity, A suitable range can be defined.

On the other hand, in order to ensure conductivity, it has been thought that it is important to reduce the contact resistance between graphite particles, and the electrical resistance of carbon black itself as a conductive auxiliary agent is compared with that of graphite. Because of its large size, it was considered important to keep the amount of carbon black mixed in order to suppress an increase in the number of contacts between carbon blacks. Thus, as a result of intensive studies, the so-called aggregate structure (also called a dendritic structure) of carbon black was developed, and the penetration resistance of the metal carbon laminated member was successfully reduced with a small amount of addition. The characteristics of carbon black will be described below.

First, (i) the particle size of carbon black was estimated to have an optimum size for increasing fluidity when mixed with graphite powder. Carbon black functions as a so-called lubricant and reduces friction between particles of graphite powder. In accordance with the guidelines, even if powders of the same size are mixed with the size of the graphite particles, the fluidity does not change and, of course, does not improve. Even if it is too small, the friction between the graphite particles cannot be improved, so it cannot contribute to the fluidity. Here, the particle diameter is not the primary particle diameter of carbon black but the aggregate diameter formed by aggregation of primary particles.

Specifically, the particle diameter of carbon black is preferably 1/1000 to 1/5 of the average diameter of the graphite powder described later, and the absolute average particle diameter is 0. .05 to 0.2 μm is preferable. The primary particle diameter of carbon black is not particularly limited, but for example, a carbon black having a particle diameter of 10 to 100 nm can be used, and preferably 10 to 70 nm. With such a primary particle size, there is no risk of destruction when a carbon resin mixed layer is molded to obtain a carbon layer, and the effect of ensuring fluidity and reducing electric resistance is reliably expressed. Can do.

In addition, (b) the fact that carbon black has a dendritic structure increases the chance of contact between particles of graphite powder with a small amount of addition, and is expected to improve conductivity by so-called percolation effect. By the way, as a physical property representing a dendritic structure, an index called dibutyl phthalate (DBP) oil absorption is common in the carbon black industry association, but in the case of fine irregularities on the surface or porous carbon black, It is known to be affected by other than the structure. Therefore, as a result of intensive studies by the present inventors, the amount of mercury absorbed by the mercury intrusion method is not affected by surface irregularities or pore structure (porous), and the carbon black dendritic structure as defined in the present invention is quantified. It was found that it is suitable for evaluation.

That is, as a physical property that defines the development of the aggregate, the absorption amount of DBP is generally used as the colloidal physical property of industrial carbon black, but the DBP value of the porous carbon black having a specific surface area exceeding 500 m ² / g is: Since the amount of DBP that has entered the pores is included, the degree of aggregate development is not reflected. Therefore, the optimum range is defined using the mercury absorption in the pore diameter range of 10 nm to 500 nm by the mercury intrusion method as a physical property value that quantitatively represents the degree of development of the dendritic structure regardless of the presence or absence of porosity. Thus, the penetration resistance of the obtained metal carbon laminated member can be controlled.

As a suitable carbon black, specifically, in the pore volume measurement by the mercury intrusion method, the mercury intrusion amount V _Hg having a pore diameter of 10 to 500 nm is preferably 1.5 to 3.0 mL / g, More preferably, it is 1.5 to 2.5 mL / g. If the mercury intrusion amount V _Hg is smaller than 1.5 mL / g, the development of the dendritic structure may be insufficient and the effect of improving conductivity may be slight. On the other hand, if it exceeds 3.0 mL / g, Because the dendritic structure develops too much, branches are destroyed during the molding process, resulting in a decrease in the dendritic structure of the carbon black contained in the resulting metal carbon laminate, and again, insufficient improvement in conductivity There is a risk of becoming. In addition, when measuring carbon black using the mercury intrusion method, in order to reduce the variation in the measured value, the state of being crushed and dispersed in water is filtered, dried, and then formed into a pellet shaped at 10 MPa It is essential that the carbon black is subjected to testing. This is because if the powder is used as it is for the mercury intrusion measurement, voids of micron size or more may be detected. A specific method will be described in the following examples.

Further, in the case of non-porous carbon black, it can be applied to the present invention as an index for assisting the regulation by the mercury intrusion method by the conventional DBP oil absorption. That is, carbon black having a DBP oil absorption of 80 to 220 mL / 100 g is preferred. More preferably, it is 100 to 200 mL / 100 g carbon. If the DBP oil absorption is less than 80 mL / 100 g carbon, the effect of reducing penetration resistance may be small because the dendritic structure is not sufficiently developed. On the other hand, if the DBP oil absorption is more than 220 mL / 100 g carbon, the dendritic structure develops too much, so the branches break in the molding process and the resulting carbon black dendritic structure contained in the resulting metal carbon laminate member As a result, the conductivity may not be improved sufficiently.

(Iii) Regarding the crystallinity of carbon black, the interaction between the resin and carbon black is reduced, that is, the affinity is reduced and the fluidity is increased. As an index for that purpose, it has been found that the crystallite size Lc in the C-axis direction by X-ray diffraction is an index suitable for the present invention. Here, it is assumed that Lc will be an index for indirectly evaluating the amount of surface functional groups, and it is considered that the amount of surface functional groups is controlled through Lc. Specifically, it has been found that when Lc is 2 to 10 nm, the fluidity is improved and the processing accuracy is increased. When Lc is less than 2 nm, the crystallinity is not sufficiently developed, the size of the carbon hexagonal network surface is small, the edge area is large, and there are many functional groups attached thereto, so the affinity with the binder resin is high. Become. As a result, there is a possibility that the effect of improving the fluidity cannot be obtained sufficiently. On the other hand, if Lc exceeds 10 nm, the affinity is too low, so that the dispersion with respect to the binder resin is worsened and the effect of improving the molding accuracy may not be sufficiently obtained.

On the other hand, as graphite powder, for example, natural graphite powder, artificial graphite powder, expanded graphite powder, expanded graphite powder, flaky graphite powder, spheroidized graphite powder, etc., as well as pulverized fibrous carbon such as carbon fiber It may be what you did. Specific examples of such fibrous carbon include PAN-based carbon fiber and pitch-based carbon fiber milled fiber. The graphite powder may be used by mixing one or more of these.

Here, regarding the graphite powder, expanded graphite and other graphite powders are divided, and the optimum particle diameter is also described below.
These graphite powders (hereinafter, the values in parentheses are the expanded graphite values) generally have an average particle size of about 1 to 100 μm (5 to 500 μm), but the finally obtained metal carbon laminated member In view of the purpose of obtaining a smoother carbon resin layer in Y and improving the adhesion to the binder resin, it is preferable to use those having an average particle diameter of 1 to 50 μm (5 to 400 μm). . More specifically, it is possible to select an optimum particle size according to the processing accuracy of molding. For example, if an accuracy of 0.01 mm is required in processing the groove shape, graphite powder having an average particle diameter of 10 μm (300 μm) or less is preferable. On the other hand, in the case of particles having an average particle diameter smaller than 1 μm (5 μm), the fluidity of the graphite powder in the heat and pressure treatment is lowered, so that the processing accuracy may be lowered. However, since expanded graphite and spheroidized graphite can be easily deformed in the pressurizing process, they have average particle diameters of 100 to 300 μm and 20 to 30 μm for processing accuracy of 0.01 mm, respectively. Is applicable. As for the size of the milled fiber, the average diameter after pulverization is preferably 1 to 30 μm, and the length is preferably an aspect ratio of 1 to 100. In addition, the average particle diameter of graphite powder can be measured using a laser diffraction particle size distribution measuring apparatus to which a laser diffraction / scattering method is applied, respectively, in the case of the binder resin and carbon black described above. In the present invention, the particle diameter (D50) at which the cumulative value of the volume cumulative particle size distribution curve is 50% of the total, the so-called median diameter, is expressed as the average particle diameter. The aspect ratio is an average value of the ratio of the fiber diameter to the length when 100 points are randomly extracted from an image of a scanning electron microscope (SEM).

Further, the particle size distribution of the graphite powder is not particularly limited. However, since the fluidity is higher when the area where the particles are rubbed is smaller, it is preferable that the particle size distribution is sharp and the contact area between the particles is small. Further, the shape of the particles is also an important factor. If the particles are spherical, the contact area between the particles is small, and high fluidity is expected. On the other hand, since the spheroidized graphite has voids with a volume fraction of up to several tens of percent inside, it is also suitable for the present invention from the viewpoint that it can be easily deformed in a normal pressure treatment process. From the viewpoint of being easily deformed, expanded graphite is also suitable as the graphite powder used in the present invention.

In the present invention, it is important for enhancing the mixing effect of carbon black that the carbon black is uniformly dispersed on the surface of the graphite powder particles. As described above, the median diameter measured using a laser diffraction particle size distribution measuring device, which is the size of the aggregate of carbon black, is 1/1000 to 1/5 of the average diameter with respect to the particle diameter of the graphite powder. Therefore, it is necessary to use a particularly devised kneading method.
Specifically, a kneading time of at least 5 minutes is required using a mixer for edible foods (for example, Robocoup Brixer BIXER-3D manufactured by FMI Co., Ltd.). Also, a so-called planetary ball mill can be used suitably. For example, using P-5 manufactured by Fritsch Japan Co., Ltd., rotating at a rotation speed of 300 rpm and using a 1 mmΦ ball, it is inverted every 10 minutes in a dry process for 30 minutes or more. Treatment is preferred. In particular, the effect of reducing electrical resistance was the highest by being dispersed under the same conditions as described above in a wet process using water as a solvent.
In addition, practical observation of whether carbon black is uniformly dispersed with respect to the graphite powder without agglomeration is performed, for example, by using the metal carbon laminate precursor of the present invention perpendicular to the metal substrate by argon ion irradiation or the like. A simple surface can be cut out and identified by SEM observation of the cross section. That is, while carbon black has a spherical shape with a particle size of about several tens to 100 nm, graphite powder has a size as large as micron or more, and the shape is obtained by using scaly flakes as the minimum basic structural unit. Can be distinguished.

In the present invention, the ratio of the binder resin and the mixed carbon powder in the carbon resin mixed layer is such that the carbon resin mixed layer of the metal carbon stacked precursor X has a predetermined porosity, and the metal carbon stacked precursor X Considering the conductivity and strength of the carbon layer in the metal carbon laminated member Y obtained by heating and pressurizing, the mass ratio of the binder resin to the mixed carbon powder is preferably 5:95 to 40:60 More preferably, it is 10:90 to 35:65. Further, the ratio of the graphite powder to the carbon black in the mixed carbon powder is preferably 99:99 by mass ratio of the graphite powder and the carbon black from the viewpoint of more surely improving the fluidity improvement effect by adding the carbon black. The ratio is preferably 1 to 90:10, more preferably 98: 2 to 92: 8. In addition, when the ratio of carbon black in the mixed carbon powder becomes too high, the upper limit of the ratio of carbon black in the mixed carbon powder is considered to be difficult to handle such as weighing and mixing because it is bulky. It is set as the mass% according to mass ratio.

Further, as the metal base material, one made of a thin metal plate can be used, and examples thereof include metal foils such as stainless steel, titanium, titanium alloy, and aluminum alloy. There is no particular limitation on the thickness of the metal substrate, and it varies depending on the use and type of the metal carbon laminate member Y obtained by heating and pressurizing the metal carbon laminate precursor X according to the present invention. When used as a separator for a polymer electrolyte fuel cell, the thickness of the metal substrate is preferably 10 to 200 μm. Among them, a separator for stationary use used at home or the like preferably uses a metal substrate having a thickness of 50 to 200 μm, and for applications that require thinning, such as a fuel cell for automobiles. It is preferable to use a metal substrate having a thickness of 10 to 100 μm.

Next, a method for producing the metal carbon laminate precursor X in the present invention will be described. Although there is no restriction | limiting in particular about the manufacturing method, Suitably, the following methods can be used according to the form of the material to be used.
First, when using a mixed powder of graphite powder and carbon black, a binder resin made of a thermosetting resin, and a slurry-like mixed material containing a solvent, the slurry-like mixed material is made of a metal base made of a thin metal plate. The binder resin in the mixed material is pre-cured by placing on the surface of the material and then heat-treating, and as shown in FIG. 3, the graphite powder of the mixed carbon powder and the carbon black particles are bonded with the binder resin. Then, a carbon resin mixed layer having a porosity of 40 to 80% by volume and a degree of curing measured by a differential scanning calorimeter of 10 to 50% is laminated on at least one surface of the metal substrate.

The solvent used in such a slurry-like mixed material is not particularly limited, and examples thereof include alcohols and ethers. In consideration of uniform dispersion of a binder resin and mixed carbon powder, preferably 1- It is preferable to use butyl alcohol, ethylene glycol monobutyl ether, or the like. Examples of means for arranging the slurry-like mixed material on the surface of the metal substrate made of a thin metal plate include commonly used printing methods, coating methods, and coating methods.

In addition, the temperature and time in the heat treatment at this time vary depending on the type of binder resin to be used, the blending of the mixed material, etc., but the carbon resin mixed layer laminated on the metal substrate has a predetermined degree of curing and voids. Can be determined to have a rate. For example, in the case of a phenol resin, heat treatment is preferably performed at a temperature of 80 to 110 ° C. for about 3 to 30 minutes, and in the case of an epoxy resin, the same heat treatment is preferably performed. This heat treatment also serves as a solvent drying process for removing the solvent from the slurry-like mixed material disposed on the surface of the metal substrate.

On the other hand, when using a powdered mixed material containing a mixed carbon powder of graphite powder and carbon black and a binder resin made of a thermosetting resin, first, a sheet body is formed from the powdered mixed material. The first heat treatment is then performed, and then the sheet body is disposed on the surface of the metal base made of a thin metal plate, and the second heat treatment is performed to pre-cure the binder resin in the mixed material. As in the case of the previous slurry-like mixed material, as shown in FIG. 3, the graphite powder of the mixed carbon powder and the carbon black particles are bound with a binder resin, and the porosity is 40 to 80% by volume. In addition, a carbon resin mixed layer having a degree of cure of 10 to 50% measured by a differential scanning calorimeter is laminated on at least one side of the metal substrate.

At this time, both the first heat treatment and the second heat treatment preliminarily cure the binder resin. However, in the first heat treatment, it is preferable to form a sheet body from at least a powdery mixed material. In this case, the powdered mixed material is preferably heat-treated under a pressure of about 0.1 to 2 MPa. Further, in the second heat treatment, it is necessary to laminate the sheet body on the metal base material. Therefore, it is preferable that the heat treatment is performed under a pressure of about 0.1 to 2 MPa. The temperature and time in the first and second heat treatments are the same as when using a slurry-like mixed material, and differ depending on the type of binder resin used and the blending of the mixed material. For example, in the case of a phenol resin In this case, both the first and second heat treatments are preferably performed at a temperature of 80 to 110 ° C. for about 3 to 30 minutes, and the same heat treatment is preferably performed for epoxy resins.

Further, without forming a sheet body from the powdery mixed material, for example, by using a mold or the like, the powdered mixed material is arranged on one side or both sides of the metal base, and the thickness is about 0.1 to 2 MPa. The binder resin may be pre-cured by heat treatment under the above pressure, and the carbon resin mixed layer may be laminated on the metal substrate. The heat treatment at this time does not need to be divided into the first and second heat treatments as in the case of forming the sheet body, and the heat treatment temperature is the same as in the first and second heat treatments described above. However, regarding the heat treatment time, since the degree of cure of the carbon resin mixed layer is mainly determined by the temperature and time of the heat treatment, it is preferable that the first heat treatment time and the second heat treatment time are combined.

In producing the metal carbon laminate precursor X in the present invention, whether to use a powdery material or a slurry material as the mixed material to be disposed on the metal substrate is formed on the metal substrate. You may make it use properly according to the thickness of a carbon resin mixed layer. That is, the slurry-like mixed material is suitable for forming a relatively thin carbon resin mixed layer, and the powder-like mixed material is suitable for forming a relatively thick carbon resin mixed layer. .

For example, when a metal carbon laminate member Y obtained by heating and pressurizing the metal carbon laminate precursor X according to the present invention is used as a fuel cell separator, in applications where thinning is required, such as an automobile fuel cell. A carbon resin mixed layer having a thickness of about 30 to 750 μm can be formed preferably using a slurry-like mixed material. On the other hand, in applications of stationary fuel cell separators used in homes and the like, it is possible to form a carbon resin mixed layer having a thickness of about 200 to 6000 μm, preferably using a powdered mixed material. In addition, these represent the thickness of the carbon resin mixed layer laminated | stacked on the one side of the metal base material. In addition, the thickness of the carbon resin mixed layer varies depending on the use of the metal carbon laminated member Y, and can be arbitrarily set. Furthermore, the slurry-like mixed material is applied and applied multiple times to form a relatively thick carbon resin mixed layer, or conversely, a thin sheet body is obtained as much as possible from the powder-like mixed material, and relatively thin carbon The resin mixed layer may be formed and is not limited to the example described here.

Also, when a slurry-like or powder-like mixed material is arranged on the surface of the metal substrate, or when a sheet body is arranged, an adhesive may be applied to the surface of the metal substrate in advance. The adhesive is not particularly limited, but preferably, the same type of resin as the binder resin of the carbon resin mixed layer formed on the metal substrate is diluted with a solvent such as alcohol and used as the adhesive. Is good.

In the metal carbon laminate precursor X in the present invention, a carbon resin mixed layer having a predetermined porosity is laminated on a metal substrate made of a thin metal plate, and is excellent in flexibility and flexibility. It may be produced as a metal carbon laminate precursor in the form of a coil and continuously wound on a wound body. That is, it is advantageous in terms of transportability and handleability by using a long metal carbon layered precursor that is continuously wound around a wound body.

Moreover, the metal carbon lamination | stacking precursor X obtained by this invention carries out the main curing of the binder resin in a carbon resin mixed layer by heat-pressing treatment, and on the metal base material 1 as shown in FIG. The metal carbon laminated member Y in which the carbon layer 11 is laminated can be manufactured. At that time, for example, when the metal carbon laminated member Y is used as a fuel cell separator, as shown in FIG. 4, a flow path such as a gas flow path for flowing a reaction gas or a refrigerant flow path for flowing a refrigerant is used. By using the mold 20 that can form a fine groove (concave portion) to be formed, the carbon layer 11 having the flow path 12 can be obtained by heat and pressure treatment.

In this case, the heating and pressurizing treatment may be performed so as to advance the curing reaction of the binder resin precured in the carbon resin mixed layer 2 of the metal carbon laminate precursor X. For example, when the metal carbon laminated member Y is used as a fuel cell separator, it is preferable to obtain a carbon layer 11 having a degree of cure of 60 to 100% as measured by a differential scanning calorimeter. As specific treatment conditions for the heat and pressure treatment, for example, when the binder resin is a phenol resin, the heat and pressure for about 1 second to 20 minutes under the heat and pressure conditions of 160 to 220 ° C. and 20 to 60 MPa. It is preferable to perform the treatment, and even in the case of an epoxy resin, the same degree of heat and pressure treatment may be performed to fully cure the binder resin. When obtaining a separator for a fuel cell, the carbon layer 11 after heat and pressure treatment should have a certain degree of porosity. According to the heat and pressure treatment under such conditions, the metal obtained The carbon layer of the carbon laminated member Y has a porosity of about 5 to 30% by volume.

FIG. 5 shows an example in which the metal carbon laminated member Y is a fuel cell separator. In addition to the flow path 12 through which the reaction gas and the like flow, an opening 13 for supplying the reaction gas, And a fixing hole 14 for stacking MEAs. However, the fuel cell separator is not limited to such a shape. FIG. 2 shows an A-A ′ cross section of the separator shown in FIG.

Moreover, the metal carbon laminate member Y obtained by heating and pressurizing the metal carbon laminate precursor X according to the present invention not only has excellent conductivity and gas impermeability, but also has excellent flexibility and corrosion resistance. It can be used other than the fuel cell separator as described above. For example, it is also suitable as a heat radiating sheet, a current collector, a gasket, various sealing materials, and the like.

Hereinafter, the metal carbon laminated precursor of the present invention will be described more specifically based on experimental examples. However, the present invention is not limited to these contents. In addition, various materials used in this experimental example, their abbreviations, and methods for measuring (evaluating) various physical property values are as follows.

<Graphite powder>
G1: Spherical graphite powder SG-BH8 (average particle diameter 8 μm) manufactured by Ito Graphite Industries Co., Ltd.
G2: Expanded graphite powder SG-BH (average particle size 20 μm) manufactured by Ito Graphite Industries Co., Ltd.
<Carbon black>
The following four types C1 to C10 were prepared as typical conductive aids.
C1: Denka acetylene black Li435 (average primary particle size 23 nm) manufactured by Denka Co., Ltd.
C2: Denka Co., Ltd. Denka Black (powder) (average primary particle size 35 nm)
C3: Ketjen Black Ketjen Black EC600JD (average primary particle size 35 nm) manufactured by Lion Specialty Chemicals
C4: Conductive grade carbon black # 4500 manufactured by Tokai Carbon Corporation
C5: Graphite carbon black # 3855 manufactured by Tokai Carbon Co.
C6: C3 EC600JD heated at 10 ° C. per minute under a flow of argon using a graphitization furnace manufactured by Tokyo Vacuum and heated at 1800 ° C. for 1 hour.
C7: Heat-treated at 2000 ° C. for 1 hour by the same method as C6.
C8: Heat-treated at 2200 ° C. for 1 hour by the same method as C6.
C9: C1 Li435 heat-treated at 1500 ° C. for 1 hour by the same method as C6.
C10: Heat-treated at 1800 ° C. for 1 hour by the same method as C9.
<Binder resin>
R1: Resol type phenol resin AH1305 (liquid type, solid content 60%) manufactured by Lignite
R2: Resol type phenol resin AH1148 (powder type) manufactured by Lignite
<Solvent>
E1: Ethylene glycol monobutyl ether <metal substrate> manufactured by Tokyo Chemical Industry Co., Ltd.
M1: Pure titanium 1 type (thickness 50 μm) manufactured by Nippon Steel & Sumitomo Metal Corporation

(Measurement of porosity)
The mercury intrusion data was measured using an automatic mercury porosimeter (Autopore IV 9520) manufactured by Shimadzu Corporation. At the time of measurement, five sheet-like samples cut into a square of 10 mm on a side from the carbon resin mixed layer of the obtained metal carbon laminate precursor were prepared and measured in a dedicated sample container. The amount of mercury intrusion (accumulated value) when pressed to 400 MPa (unit: mL) is the void of the carbon resin mixed layer, and the ratio of this void to the volume of the carbon resin mixed layer calculated from the sample shape and thickness is the porosity. Define.

[Measurement of degree of cure]
Using a differential scanning calorimeter (abbreviated as DSC) (DSC 214 Polyma, manufactured by NETZSCH), DSC data of the sample to be measured (carbon resin mixed layer of metal carbon laminate precursor) was measured. The measurement conditions were a heating rate of 10 ° C./minute, the total heat generation amount was calculated from the exothermic peak using the software attached to the apparatus, the total heat generation amount of the mixed material used was calculated in the same manner, and the degree of cure ( DSC:%) was calculated.
Curing degree (%) = 100 − [(total calorific value of carbon resin mixed layer / total calorific value of mixed material) × 100]

[Measurement of Lc by X-ray diffraction method]
Using CuKα rays as an X-ray source, an X-ray diffraction pattern of carbon black was measured by a so-called powder X-ray diffraction method. The slit conditions of the apparatus were set to a diverging slit of 1 °, a light receiving slit of 0.15 mm, and a scattering slit of 1 °. For the measurement, SmartLab manufactured by Rigaku Corporation was used. From the peak position and half-value width of the (002) plane diffraction line of the graphite crystal observed around 26 °, the size of the crystallite size by the 002 diffraction line, that is, the crystallite in the C-axis direction is calculated using the Scherrer equation. The size Lc was calculated. Note that Lc was calculated assuming that the K value of the Scherrer equation was 1.05.

[Measurement of mercury absorption by mercury intrusion method]
Weigh 0.5 to 2.0 g of carbon black, put it in a 50 mL glass sample bottle, and further 10 to 20 g of glass beads with a diameter of 1 mm and 15 g of water. For the purpose of sufficient dispersion, a slurry was prepared using a rocking mill (RM-01 manufactured by Seiwa Giken Co., Ltd.). The treatment conditions were treatment at 300 rpm for 10 minutes. The prepared slurry is filtered under reduced pressure and then vacuum dried at 100 ° C. for several hours. The powder is compacted at 10 MPa using a cylindrical pellet mold having a diameter of 10 mm, and a pellet having a diameter of 10 mm and a thickness of several mm. This was used as a sample for mercury intrusion. The sample thus formed is loaded into a sample container of a measuring device (Autopore IV9520 manufactured by Shimadzu Corporation), and mercury is injected under the conditions of an initial introduction pressure of 5 kPa and a maximum injection pressure of 400 MPa. Absorption was measured. From the measurement results, the horizontal axis represents the mercury pressure converted to pore diameter (μm), and the vertical axis represents mercury absorption (cc / g) to obtain these relationships, and the pore diameter is between 10 nm and 500 nm. Mercury absorption amount (mercury intrusion amount) V _Hg was calculated. Conversion to pore diameter was performed by analysis software attached to the apparatus.

[Evaluation of groove shape by mold molding]
As shown in FIG. 6A, the width of the recesses a = 0.4 mm, the interval of the recesses b = 0.4 mm, the depth of the recesses c = 0.4 mm, and the length of the recesses (not shown) = 100 mm. Using the test mold 41 having a total of 100 rectangular grooves 42, the metal carbon laminate precursor obtained in the experimental example was subjected to a heat and pressure treatment for 10 seconds under a heat and pressure condition of a temperature of 200 ° C. and a pressure of 40 MPa. went. About the obtained metal carbon lamination | stacking member, the groove shape formed in the carbon layer 31 (what the carbon resin mixed layer of the metal carbon lamination | stacking precursor was heat-pressed) was evaluated. In addition, the recessed part of this test metal mold | die 41 was processed by R = 0.02.

Specifically, using a Macroscope VR-3000 manufactured by Keyence Corporation, measurement is performed in a direction crossing the plurality of rectangular grooves 42 in the test mold 41 in the width direction (indicated by broken arrows in FIG. 6). The total of straight lines D forming the bottom surface of the groove 42 was obtained. Similarly, the carbon layer 31 is measured in the direction crossing the plurality of protruding protrusions 32 formed by the test mold 41 in the width direction (broken arrow direction in FIG. 6) using the macroscope. The sum of straight lines D ′ forming the tops of the respective protrusions 32 was calculated, and the molding accuracy coefficient was calculated from the following formula. FIG. 6B is an enlarged view of the straight line D that forms the bottom surface of the rectangular groove 42 and the straight line D ′ that forms the top of the protruding protrusion 32. Moreover, the metal carbon lamination | stacking precursor in this experiment example forms a carbon resin mixed layer on the front and back both surfaces of a metal base material, and heat-presses each carbon resin mixed layer using the test die 41, respectively. However, in this groove shape evaluation, one carbon layer of the obtained metal carbon laminated member was evaluated, and a molding accuracy coefficient was calculated.
Molding accuracy factor (%) = [(total of straight lines D ′) / (total of straight lines D)] × 100

(Evaluation of penetration resistance)
With respect to the metal carbon laminated member after the heat and pressure treatment obtained in the above [Evaluation of groove shape by mold molding], the penetration resistance was measured as follows.
First, a square plate made of gold (Au) having a side of 1 cm is arranged vertically as electrodes, and a sample (metal carbon laminated member) to be measured is sandwiched between them and a pressure of 5 MPa is applied, and 10 mA is applied. The direct current was passed, the voltage between the upper and lower electrodes at that time was measured, and the resistance value was calculated.

(Experimental example 1: Control of porosity and curing degree by heat treatment)
First, 9.5 parts by mass of G1 spheroidal graphite powder as graphite powder and 0.5 part by mass of C1 Li435 as carbon black were prepared, and these were used for commercial cutter mixers (manufactured by FMI Co., Ltd.). The mixed carbon powder in which the graphite powder and the carbon black powder were sufficiently mixed was prepared by placing in a RoboCup Brixer R-3D) and treating for 30 minutes. Next, together with the obtained mixed carbon powder, 2 parts by mass of R1 resol type phenol resin as a binder resin and 7 parts by mass of E1 ethylene glycol monobutyl ether as a solvent are sealed in a container, and manufactured by THINKY Were kneaded at 300 rpm for 1 minute, and then kneaded at 1000 rpm for 2 minutes to obtain a slurry-like mixed material.

Next, the surface of a 250 mm × 400 mm × 50 μm thick titanium foil (M1: pure titanium 1 type) was thoroughly washed with acetone in advance, and the slurry-like mixed material obtained above was applied to one surface thereof. . When coating, adjust the gap so that it has a predetermined thickness after heat treatment with a doctor blade, and apply an applicator moving speed of 20 mm / min using an automatic coating machine (BEVS Adjustable Applicator). Worked. The coating area was 15 cm × 35 cm.

Next, after putting the titanium foil in a warm air dryer set at 80 ° C. and performing a solvent drying treatment for 5 minutes, using a hot press machine preliminarily kept at 90 ° C. under a pressure of 0.8 MPa. For 1 minute. Next, a slurry-like mixed material was applied to the other surface of the titanium foil in the same manner as described above, and after the solvent was dried, heat treatment was performed under the same conditions. In this way, a carbon carbon mixed precursor according to Experiment No. 1-1 having a total thickness of about 110 μm provided with a carbon resin mixed layer with a thickness of 30 μm on each side of the titanium foil was obtained. In addition, the metal carbon laminate precursors according to Experiment Nos. 1-2 to 1-24 were prepared in the same manner as in Experiment No. 1-1 except that the blending of the mixed materials and the heat treatment conditions were changed as shown in Table 1. Obtained.

About the metal carbon lamination | stacking precursor of each experiment No. obtained in the said Experimental example 1, the porosity and hardening degree of the carbon resin mixed layer were measured by the method mentioned above. Further, the metal carbon laminate precursor was subjected to heat and pressure treatment by the method described in [Evaluation of groove shape by mold molding] and [Evaluation of penetration resistance], and the penetration resistance of the obtained metal carbon laminate member was obtained. The molding accuracy coefficient of the carbon layer was determined. The results are shown in Table 2. Further, for the carbon black used, Lc and V _Hg obtained according to the previous [Measurement of Lc by X-ray diffraction method] and [Measurement of mercury absorption by mercury intrusion method] were calculated, and the results are summarized in Table 2. Show.

(Experimental example 2: Effect of preparation method of mixed carbon powder)
By changing the preparation method of the mixed carbon powder in Experimental Example 1, the effect of dispersing graphite and carbon black was examined. In the cutter mixer apparatus (referred to as apparatus A) used in Experimental Example 1, the mixing treatment time was changed as shown in Table 3. Further, for the purpose of improving the dispersion state of the mixed carbon powder, as shown in Table 3, mixing was performed using a planetary ball mill (planet ball mill P-5 manufactured by Fritsch Japan Co., Ltd., referred to as device B). The container / ball used in the apparatus B was made of zirconia, and the ball size was 1 mmφ. Using an 80 mL container, 25 mL of mixed carbon powder and 25 mL of balls were placed in the container and processed at the number of rotations and time shown in Table 3.

The obtained slurry-like mixed material was applied to the titanium foil M1 one side at a time in the same manner as in Experimental Example 1, subjected to a solvent drying treatment at 80 ° C. for 5 minutes, and then kept hot at 90 ° C. in advance. Experiment No. 2 in which a heat treatment was performed for 1.7 minutes under a pressure of 0.8 MPa, a carbon resin mixed layer having a thickness of 30 μm on each side of the titanium foil, and a total thickness of about 110 μm. Each metal carbon lamination | stacking precursor was obtained. About the obtained metal carbon lamination | stacking precursor, the penetration resistance and the shaping | molding precision coefficient of the carbon layer were calculated | required like the experimental example 1 like the porosity and the hardening degree of a carbon resin mixed layer. The results are summarized in Table 4.

(Experimental example 3: Use of powdery mixed material)
Prepare 6.65 parts by mass of G1 spheroidal graphite powder as graphite powder and 0.5 parts by mass of C1 acetylene black Li435 as carbon black. First, G1 and C1 are sufficient under the same method and conditions as in Experimental Example 1. Then, 2 parts by mass of R2 resol type phenol resin was prepared as a binder resin, and this R2 was added, and the same apparatus was used for the treatment for dispersion with a treatment time of 5 minutes. . By the way, in the cutter mixer used in this experimental example, the processing time is optimally about 5 minutes, and when it exceeds 10 minutes, a thermosetting resin such as R2 is heated in the cutter mixer process and fused to the carter blade. The penetration resistance of the metal carbon laminated member finally obtained is good at 2.9 mΩ · cm ² , but the porosity of the carbon resin mixed layer in the metal carbon laminated precursor is reduced (31%) In addition, the precision of the molding process due to the heating and pressurizing treatment was reduced (82%), and it was not applicable to the present invention.

For the mixture of the mixed carbon powder and the resin powder R2 prepared and sufficiently dispersed in this way, 2.85 parts by mass of G2 which is expanded graphite is further prepared, and these are mixed with a rocking mixer RM manufactured by Aichi Electric Co., Ltd. A mixed material consisting of powder was prepared by mixing at -10 rpm for 30 minutes at -10 rpm. Since G2 which is expanded graphite exfoliates the material when a strong share is applied, the result is that the aggregation is increased. Therefore, the above conditions are selected because the method of applying the share requires attention.

The mixed material composed of the powder obtained above is sandwiched between plates of 49.7 mm square × 10 mm thickness in a 50 mm square mold so as to have a predetermined thickness, and the pressure is 2 MPa and the temperature is 90 ° C. for 10 minutes. Were subjected to hot pressing (first heat treatment) to obtain a sheet body of 50 mm × 50 mm × thickness of about 3 mm. Similarly, a total of two sheet bodies are prepared, and the sheet bodies are overlapped on both the front and back surfaces of a 50 mm × 50 mm × 50 μm thick titanium foil (M1: pure titanium type), and the above-mentioned inner dimension of 50 mm square is obtained. Using a mold, hot pressing was performed at a pressure of 2 MPa and a temperature of 90 ° C. for 10 minutes (second heat treatment). In this way, a carbon carbon mixed precursor of Experiment No. 3-1 having a total thickness of about 6 mm provided with a carbon resin mixed layer having a thickness of about 3 mm on each of the front and back surfaces of the titanium foil was obtained.

In addition, the metal carbon laminate precursor of Experiment No. 3-2 was obtained in the same manner as in Experiment No. 3-1, except that the blending of the mixed materials and the heat treatment conditions were changed as shown in Table 5. It was. About the obtained metal carbon lamination | stacking precursor, the penetration resistance and the shaping | molding precision coefficient of the carbon layer were calculated | required like the experimental example 1 like the porosity and the hardening degree of a carbon resin mixed layer. The results are summarized in Table 6.

Further, in the same manner as described above, a metal carbon lamination precursor of Experiment No. 3-1 and a metal carbon lamination precursor of Experiment No. 3-2 were prepared, respectively, and heated and pressurized at a temperature of 200 ° C. and a pressure of 40 MPa. Under the conditions, press molding (heat pressure treatment) for 20 minutes was performed. The thermal conductivity in the thickness direction (pressure direction) of the metal carbon laminate obtained in this way was measured using a thermal diffusivity / thermal conductivity measuring device (eye phase mobile 1u manufactured by Eye Phase). As a result, the metal carbon laminated member according to Experiment No. 3-1 was 26.0 W / m · K, and the metal carbon laminated member according to Experiment No. 3-2 was 16.0 W / m · K. By the way, among the heat-dissipating sheets that are used to diffuse (heat-dissipate) heat from heat generating elements such as CPUs of small electronic devices such as smartphones and tablets, The thermal conductivity in the thickness direction is about 4 to 7 W / m · K (for example, catalog of carbon graphite MHM manufactured by Idle Dream Co., Ltd. http://www004.upp.so-net.ne.jp/ill-dream/ See 361161651.pdf). That is, if the metal carbon lamination | stacking precursor which concerns on this invention is used, the thermal radiation sheet excellent in thermal conductivity can be obtained. In addition, the metal carbon laminate precursor of the present invention is reinforced by a metal base material and has excellent flexibility and flexibility, but the carbon layer after heat and pressure treatment has excellent molding accuracy. In addition to high adhesion, it is also possible to enhance the heat dissipation effect by providing an uneven shape. For example, in addition to the heat dissipation sheet of a chip such as a CPU mounted on a small electronic device as described above, a large display It can also be suitably used when it is mounted on the back surface of LED lighting or the like to dissipate the heat generated.

(Experimental example 4: Effect of carbon black species and mixing amount)
As shown in Table 7, experimental examples Nos. 4-1 to 4-9 were made in the same manner as in experimental examples No. 1-6 except that the type of carbon black was changed. Experimental Examples Nos. 4-10 to 4-17 were conducted by changing the mixing ratio of G1 and C10 in .4-9. At that time, in Experimental Example No. 4-17, a planetary ball mill (Apparatus B) was used instead of the cutter mixer (Apparatus A) in the case of Experimental Example No. 1-6 as a method for adjusting the mixed carbon powder. Processing for 20 minutes was performed at 200 rpm. Except these, it carried out similarly to Experimental example 1, and obtained each metal carbon lamination | stacking precursor of experiment No.4. About the obtained metal carbon lamination | stacking precursor, the penetration resistance and the shaping | molding precision coefficient of the carbon layer were calculated | required like the experimental example 1 like the porosity and the hardening degree of a carbon resin mixed layer. The results are summarized in Table 8.

As can be seen from the experimental results of the above experimental examples 1 to 4, while using a mixed carbon powder of graphite powder and carbon black, the porosity is 40 to 80% by volume and the DSC curing degree is 10 to 50%. If it is a metal carbon laminate precursor with a carbon resin mixed layer, it can be obtained while exhibiting excellent molding accuracy in heat and pressure treatment using a mold compared to other metal carbon laminate precursors. The effect of reducing the penetration resistance of the laminated member can be surely exhibited.

1: metal substrate, 2: carbon resin mixed layer, 3: graphite powder, 4: carbon black, 5: binder resin, 11: carbon layer, 12: flow path, 13: opening, 14: fixing hole, 20: Die, 31: carbon layer, 32: protruding protrusion, 41: test mold, 42: rectangular groove.

Claims

A metal carbon laminate precursor capable of obtaining a metal carbon laminate member of a metal substrate and a carbon layer by a heating and pressurizing treatment heated under pressure,
A carbon resin mixed layer containing a mixed carbon powder of graphite powder and carbon black and a binder resin made of a thermosetting resin is laminated on at least one surface of a metal base made of a thin metal plate, and the carbon resin mixed layer is The porosity is 40 to 80% by volume, the degree of cure measured by a differential scanning calorimeter is 10 to 50%, and the binder resin in the carbon resin mixed layer is fully cured by heat and pressure treatment, A metal carbon laminate precursor characterized in that a metal carbon laminate member in which a carbon layer is laminated on a metal substrate can be obtained.
The mass ratio of the binder resin and the mixed carbon powder in the carbon resin mixed layer is 5:95 to 40:60, and the mass ratio of the graphite powder to the carbon black in the mixed carbon powder is 99: 1 to 90: The metal carbon laminate precursor according to claim 1, which is 10.
The metal carbon laminate precursor according to claim 1 or 2, wherein the carbon black is one or more selected from the group consisting of porous carbon black, acetylene black, and highly crystalline carbon black.
The metal carbon laminate precursor according to any one of claims 1 to 3, wherein a crystallite size Lc in the C-axis direction by powder X-ray diffraction of the carbon black is 2 nm or more and 10 nm or less.
The carbon black has a mercury intrusion amount V Hg having a pore diameter of 10 nm to 500 nm in a pore volume measurement by a mercury intrusion method of 1.5 mL / g or more and 3.0 mL / g or less. The metal carbon lamination | stacking precursor in any one.
The metal carbon laminate precursor according to any one of claims 1 to 5, wherein the metal carbon laminate member is a separator for a fuel cell.
A method for producing a metal carbon laminate precursor capable of obtaining a metal carbon laminate member of a metal substrate and a carbon layer by a heating and pressurizing treatment heated under pressure,
A mixed carbon powder of graphite powder and carbon black, a binder resin made of a thermosetting resin, and a slurry-like mixed material containing a solvent are arranged on the surface of a metal substrate made of a metal thin plate, heat-treated, and the mixed material By pre-curing the binder resin therein, a carbon resin mixed layer having a porosity of 40 to 80% by volume and a curing degree measured by a differential scanning calorimeter of 10 to 50% is formed of a metal thin plate. A method for producing a metal carbon lamination precursor, comprising laminating at least one side of a substrate.
A method for producing a metal carbon laminate precursor capable of obtaining a metal carbon laminate member of a metal substrate and a carbon layer by a heating and pressurizing treatment heated under pressure,
A first heat treatment for forming a sheet body from a mixed powder of graphite powder and carbon black and a powdered mixed material containing a binder resin made of a thermosetting resin, and the sheet body is made of a metal sheet. 2nd heat treatment performed on the surface of the base material, and by pre-curing the binder resin in the mixed material, the porosity is 40-80% by volume and measured by a differential scanning calorimeter A method for producing a metal carbon laminate precursor, comprising: laminating a carbon resin mixed layer having a degree of curing of 10 to 50% on at least one surface of a metal substrate made of a metal thin plate.
The mass ratio of the binder resin and the mixed carbon powder in the mixed material is 5:95 to 40:60, and the mass ratio of the graphite powder to the carbon black in the mixed carbon powder is 99: 1 to 90:10. The manufacturing method of the metal carbon lamination | stacking precursor of a certain 7 or 8.
The metal carbon laminate according to any one of claims 7 to 9, wherein the carbon black is one or more selected from the group consisting of porous carbon black, acetylene black, and highly crystalline carbon black. A method for producing a precursor.
11. The method for producing a metal-carbon laminated precursor according to claim 7, wherein the carbon black has a crystallite size Lc in the C-axis direction by powder X-ray diffraction of 2 nm or more and 10 nm or less.
The carbon black has a mercury intrusion amount V Hg of not less than 1.5 mL / g and not more than 3.0 mL / g in pore volume measurement by mercury intrusion method with a pore diameter of 10 nm to 500 nm. The manufacturing method of the metal carbon lamination | stacking precursor in any one.
13. The method for producing a metal carbon laminate precursor according to claim 7, wherein the metal carbon laminate member is a separator for a fuel cell.