JP7273378B2 - Method for producing particle-coated foil and method for producing metal-particle composite - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a particle-coated foil in which particles are coated on the foil, and a method for producing a metal-particle composite.

Here, in the present specification and claims, the term "aluminum" is used to include both pure aluminum and aluminum alloys, and the term "copper" is used to mean pure copper and aluminum alloys, unless otherwise specified in the text. It is used in the sense of including both copper alloys.

A metal-particle composite material such as a metal-carbon particle composite material generally has a high thermal conductivity or a low coefficient of linear expansion and is used as a functional material.

As a method of manufacturing such a composite material, a method of adding carbon fibers as carbon particles to molten aluminum, stirring and mixing, and cooling and solidifying (melt stirring method), a method of pushing molten aluminum into a carbon molded body having voids. (Molten metal forging method), a method of pressurizing and heating a mixture of aluminum powder and carbon powder (powder metallurgy method), and a method of extruding a mixture of aluminum powder and carbon powder (powder extrusion method). there is

Since these methods use molten aluminum or aluminum powder, the manufacturing work is complicated and the manufacturing equipment is large.

In Japanese Patent No. 5150905 (Patent Document 1), a preform is formed by forming a film containing carbon fibers as carbon particles on a sheet-like or foil-like metal support, and a plurality of these are stacked to form a laminate. is formed, and the laminate is heated and pressure-welded to integrate the preforms, thereby disclosing a method for producing a metal-based carbon fiber composite material as a metal-carbon particle composite material. In this method, the composite material obtained tends to have a higher thermal conductivity in one direction in which the carbon fibers are oriented.

In Japanese Patent No. 4441768 (Patent Document 2), a sintered precursor is formed using a mixture of flake graphite powder and a predetermined flake metal powder, and the sintered precursor is sintered under pressure, A method of making a metal-graphite composite as a metal-carbon particle composite is disclosed. This method has a problem of high manufacturing cost.

Japanese Patent Application Laid-Open No. 2006-1232 (Patent Document 3) discloses a method of manufacturing a composite material with high thermal conductivity and low thermal expansion by hot-press sintering a composite in which a crystalline carbon material layer and a metal layer are laminated. disclosed. A possible problem with this method is that it is difficult to set the sintering conditions for the composite.

International Publication No. 2017/110140 (Patent Document 4) discloses that a carbon fiber layer is formed on a metal foil by coating a metal foil with a coating liquid containing carbon fibers as carbon particles using a gravure coating device. A metal comprising a step of obtaining the formed coated foil, a step of forming a laminated body in which a plurality of coated foils are laminated, and a step of joining and integrating the coated foils by heating the laminated body- A method of manufacturing a carbon fiber composite is disclosed.

Other documents disclosing metal-carbon particle composites include JP-A-2015-25158 (Patent Document 5), JP-A-2015-217655 (Patent Document 6) and JP-A-2017-145431 (Patent Document 7).

The metal-carbon particle composite material obtained by the manufacturing method disclosed in Patent Documents 1 and 4 is a state in which a plurality of metal layers made of a metal matrix and carbon particle dispersion layers in which carbon particles are dispersed in the metal matrix are alternately laminated. It is integrally joined to

Here, hereinafter, in such a metal-particle composite material such as a metal-carbon particle composite material, the stacking direction of the metal layer and the particle dispersion layer is defined as the thickness direction of the composite material, and the thickness direction of the composite material is defined as The plane and direction perpendicular to it are defined as the plane and direction of the composite.

Furthermore, in a laminate of particle-coated foils coated with particles, the lamination direction of the particle-coated foil is defined as the thickness direction of the laminate, and the plane perpendicular to the thickness direction of the laminate and its direction is defined as the plane and planar direction of the laminate.

Japanese Patent No. 5150905 Japanese Patent No. 4441768 Japanese Unexamined Patent Application Publication No. 2006-1232 WO2017/110140 JP 2015-25158 A JP 2015-217655 A JP 2017-145431 A

As in the method for producing a metal-carbon fiber composite material disclosed in Patent Document 4 above, when a coating liquid containing carbon particles such as carbon fibers is applied onto a metal foil by a gravure coating device, generally compared A coating liquid having a relatively low viscosity is used. Therefore, the carbon particles tend to settle in the coating liquid tank (including the coating liquid pan), and in particular, the carbon particles having a large particle size tend to settle. Therefore, when the coating liquid in the coating liquid tank is applied onto the metal foil, the problem of uneven dispersion of the carbon particles on the metal foil tends to occur.

When a metal-carbon particle composite material is produced according to the production methods of Patent Documents 1 and 4 using a carbon particle-coated foil in which the carbon particles are unevenly dispersed, physical properties in the plane direction of the composite material (e.g., thermal conductivity , linear expansion coefficient).

Therefore, when coating is performed by a gravure coating apparatus, it is necessary to devise a device for uniformizing the state of dispersion of the carbon particles in the coating liquid in the coating liquid tank.

The present invention has been made in view of the above-described technical background, and an object thereof is to provide a method for producing a particle-coated foil that can easily achieve a uniform dispersion state of particles on the foil, and a particle-coated foil. An object of the present invention is to provide a method for producing a metal-particle composite material using the metal-particle composite material.

The present invention provides the following means.

1) A method for producing a particle-coated foil in which particles are coated on the foil, comprising:
Including a step of applying a coating liquid containing particles, a binder and a solvent for the binder on the foil and drying it,
The particles have an average length of 0.10 mm or more in the longest axial direction,
In the step of coating and drying, the coating solution is applied onto the foil by a bar coater having a bar with a gap width of 1.5 times or more the average length of the particles in the longest axial direction. A method for producing a particle-coated foil.

2) The method for producing a particle-coated foil according to the above item 1, wherein scale-like graphite particles are used as the particles.

3) The method for producing a particle-coated foil according to the preceding item 1, wherein carbon fibers are used as the particles.

4) The method for producing a particle-coated foil according to any one of the preceding items 1 to 3, wherein at least one selected from the group consisting of polyethylene oxide, polyvinyl alcohol and acrylic resin is used as the binder.

5) The method for producing a particle-coated foil according to any one of the preceding items 1 to 4, wherein a metal foil is used as the foil.

6) The method for producing a particle-coated foil according to 5 above, wherein the metal foil is an aluminum foil.

7) A step of forming a laminate in which a plurality of particle-coated foils obtained by the method for producing a particle-coated foil according to the preceding item 5 or 6 are laminated;
and sintering the laminate.

The present invention has the following effects.

In the preceding item 1, when the average length of the particles in the longest axis direction is 0.10 mm or more, for example, the metal-particle composite material produced using the particle-coated foil can achieve high thermal conductivity.

Furthermore, by using a bar coater equipped with a bar having a predetermined gap width as a coating device, coating can be performed using a coating liquid having a relatively high viscosity, and the coating liquid can be applied onto the foil. Clogging of particles at the contact portion between the foil and the bar can be suppressed. As a result, it is possible to easily achieve a uniform dispersion state of the particles on the foil.

Therefore, the particle-coated foil produced by the production method in 1 above can be suitably used as an intermediate material for producing a functional material such as a metal-carbon particle composite.

In the preceding item 2, by using scaly graphite particles as particles, for example, a metal-carbon particle composite material (more specifically, a metal-scaly graphite particle composite material) produced using a particle-coated foil is further High thermal conductivity can be achieved.

In the preceding item 3, by using carbon fibers as particles, for example, a metal-carbon particle composite material (more specifically, a metal-carbon fiber composite material) manufactured using a particle-coated foil can be reduced in linear expansion coefficient. It is possible.

In the preceding item 4, it is possible to ensure the adhesion of the particles to the foil, and to reliably prevent the binder from remaining in the metal-particle composite material produced using the particle-coated foil, for example.

In the above item 5, by using a metal foil as the foil, for example, a metal-particle composite material can be produced using a particle-coated foil.

In 7 above, by using an aluminum foil as the metal foil, for example, a particle-coated foil can be used to produce an aluminum-particle composite material that is a lightweight metal-particle composite material with high workability.

In item 7 above, a metal-particle composite material having high thermal conductivity can be produced by an inexpensive process.

FIG. 1 is a flow diagram of a manufacturing process of a metal-carbon particle composite material as a metal-particle composite material according to one embodiment of the present invention. FIG. 2 is a schematic diagram explaining the manufacturing process of the carbon particle-coated foil. FIG. 3 is a schematic diagram of the shape of some carbon particles to illustrate the longest axial length of the carbon particles. FIG. 4 is a schematic front view of a first form of bar in the bar coater. FIG. 5 is a schematic front view of a second form of bar in the bar coater. FIG. 6 is a schematic front view of a third form of bar in the bar coater. FIG. 7 is a schematic diagram of cutting a strip of the same carbon particle-coated foil. FIG. 8 is a schematic front view of a laminate of carbon particle-coated foils. FIG. 9 is a schematic diagram of sintering the laminate by a pressure heating sintering apparatus. FIG. 10 is a schematic cross-sectional view of a metal-carbon particle composite. FIG. 11 is a schematic diagram of a case in which the laminate of the carbon particle-coated foil is formed by winding a strip of the carbon particle-coated foil into a roll a plurality of times. FIG. 12 is a schematic diagram of the state in which the laminate is loaded into a container of an extrusion processing apparatus. FIG. 13 is a schematic diagram of a state in the middle of extrusion processing of the same laminate by the same extrusion processing apparatus. FIG. 14 is a schematic diagram of another example of a bar coater. FIG. 15 is a schematic front view of the cooler.

Several embodiments of the invention will now be described below with reference to the drawings.

A method for producing a metal-particle composite material according to an embodiment of the present invention produces a metal-carbon particle composite material 10 shown in FIG. 10 as a metal-particle composite material. Therefore, in this embodiment, carbon particles are used as the solid particles, and metal foil is used as the foil.

In this figure, hatching attached to the cross section of the composite material 10 is omitted in order to facilitate understanding of the internal structure of the composite material 10 .

Composite material 10 includes a metal matrix 13 and a large number of carbon particles 1 dispersed in metal matrix 13 . More specifically, the composite material 10 is formed by joining and integrating (in detail Then, it is sintered and integrated). Carbon particles 1 are substantially absent in each metal layer 12 .

Here, in this embodiment, for convenience of explanation, the lamination direction of the metal layer 12 and the carbon particle dispersed layer 11 is defined as the thickness direction of the composite material 10, and the plane perpendicular to the thickness direction of the composite material 10 That direction is defined as the plane of the composite 10 and the planar direction. Therefore, each carbon particle dispersed layer 11 of the composite material 10 is formed by dispersing the carbon particles 1 in the metal matrix 13 in the planar direction of the composite material 10 .

As shown in FIG. 1, the method for manufacturing a composite material 10 includes a step S1 of manufacturing a carbon particle-coated foil 8 in which carbon particles 1 as particles are coated on a metal foil 7 as a foil as a particle-coated foil. (This step is hereinafter also referred to as “manufacturing step S1 of carbon particle-coated foil 8”), and step S3 (see FIG. 8) of forming laminate 9 (see FIG. 8) in which a plurality of carbon particle-coated foils 8 are laminated. This step is hereinafter also referred to as a “laminate formation step S3”) and a step S4 of sintering the laminate 9 (this step is also hereinafter referred to as a “sintering step S4”) (see FIG. 9). I'm in.

Therefore, the carbon particle-coated foil 8 is used as an intermediate material for manufacturing the metal-carbon particle composite material 10, which is a functional material. Note that the carbon particle-coated foil 8 is hereinafter also simply referred to as the "coated foil 8".

The manufacturing step S1 of the coated foil 8 includes, as shown in FIG. ). In this embodiment, a strip 7A of the metal foil 7 (that is, a long belt-shaped metal foil 7) is used as the metal foil 7. As shown in FIG. Furthermore, the intended coating surface 7a of the strip 7A of the metal foil 7 to which the coating liquid 5 is applied is at least one of the surfaces on both sides in the thickness direction of the strip 7A of the metal foil 7. In terms of form, it is one surface in the thickness direction of the strip 7A of the metal foil 7, and more specifically, it is the upper surface of the strip 7A of the metal foil 7. As shown in FIG.

The material of the metal foil 7 (more specifically, the strip 7A of the metal foil 7) forms the matrix 13 of the composite material 10. As shown in FIG. The type of metal foil 7 is not limited, and it is particularly desirable to use aluminum foil or copper foil as metal foil 7 . The reason is that a composite material with high thermal conductivity can be obtained. In particular, when an aluminum foil is used as the metal foil 7, a lightweight composite material 10 with high workability can be produced.

The thickness of the strip 7A of the metal foil 7 is not limited, and is preferably 5 to 500 μm. Since the strip 7A of the metal foil 7 has a thickness of 5 μm or more, the strip 7A of the metal foil 7 can be easily manufactured. By setting the thickness of the strip material 7A of the metal foil 7 to 500 μm or less, the composite material 10 having a high carbon particle content can be reliably manufactured. A particularly desirable lower limit for the thickness of the strip 7A of the metal foil 7 is 10 μm, and a particularly desirable upper limit is 50 μm.

The width of the strip 7A of the metal foil 7 is not limited, and is, for example, 100-1500 mm.

As shown in FIG. 2, the coating liquid 5 contains carbon particles 1, a binder 2, and a solvent 3 for the binder 2 in a mixed state.

The type of the carbon particles 1 is not limited, and the carbon particles 1 are usually carbon fibers, natural graphite particles (eg, scale-like graphite particles), artificial graphite particles (eg, anisotropic graphite particles, isotropic graphite particles). graphite particles) and pyrolytic graphite particles are used.

When carbon fibers are used as the carbon particles 1, the composite material 10 can be made to have a low coefficient of linear expansion. The type of carbon fiber is not limited, and the carbon fiber is one selected from the group consisting of PAN-based carbon fiber, pitch-based carbon fiber, and carbon nanofiber (eg, carbon nanotube, vapor growth carbon fiber). or a mixture of carbon fibers of different types.

Furthermore, as the carbon fiber, it is particularly desirable to use pitch-based carbon fiber among PAN-based carbon fiber and pitch-based carbon fiber. The reason for this is that the pitch-based carbon fiber has a higher thermal conductivity in the fiber direction than the PAN-based carbon fiber, so that the composite material 10 having a high thermal conductivity can be obtained.

The type of natural graphite particles is not limited, and scale-like graphite particles are particularly preferably used as the natural graphite particles. In this case, the thermal conductivity of the composite material 10 can be increased.

Here, the size of the carbon particles 1 contained in the coating liquid 5 will be described below with reference to FIG.

FIG. 3 shows the shapes of some carbon particles 1 arbitrarily selected from various shapes of carbon particles 1 contained in the coating liquid 5 . “L1” is the length of the carbon particle 1 in the longest axial direction. Further, the average length of the carbon particles 1 in the longest axial direction is defined as "AL1". The length L1 of the carbon particles 1 in the longest axial direction means the length of the carbon particles 1 in the longest direction. Therefore, when carbon fibers are used as the carbon particles 1, L1 is the fiber length of the carbon fibers, and AL2 is the average fiber length of the carbon fibers.

Further, the length of the carbon particles 1 contained in the coating liquid 5 in the shortest axial direction is defined as "L2", and the average length of the carbon particles 1 in the shortest axial direction is defined as "AL2". The length L2 of the carbon particles 1 in the shortest axial direction means the length of the carbon particles 1 in the shortest direction. Specifically, when flaky graphite particles are used as the carbon particles 1, L2 is the thickness of the flaky graphite particles, and AL2 is the average thickness of the flaky graphite particles. Further, when carbon fibers are used as the carbon particles 1, for example, L2 is the fiber diameter of the carbon fibers, and AL2 is the average fiber diameter of the carbon fibers.

"AL1" and "AL2" of the carbon particles 1 can be calculated by the following method.

100 carbon particles arbitrarily selected from a large number of carbon particles dispersed on a glass plate are observed with an optical microscope, and the length L1 in the longest axial direction and the length L2 in the shortest axial direction of each carbon particle are measured. do. The calculated average value of L1 is defined as the average length AL1 in the longest axial direction of the carbon particles, and the calculated average value of L2 is defined as the average length AL2 in the shortest axial direction of the carbon particles. In addition, when it is difficult to measure L2 of the carbon particles by the above method, an arbitrary cross section of the metal-carbon particle composite material 10 is observed with an electron microscope, and a large number of carbon particles exposed in the cross section are measured. The length L2 in the shortest axial direction of 100 carbon particles arbitrarily selected from among them may be measured, and the arithmetic average value of L2 may be taken as the average length AL2 in the shortest axial direction of the carbon particles.

In the carbon particles 1 contained in the coating liquid 5, the average length AL1 in the longest axis direction of the carbon particles 1 must be 0.10 mm or more (that is, AL1≧0.10 mm). When AL1 is 0.10 mm or more, the interfacial thermal resistance between the carbon particles 1 and the metal matrix 13 inside the composite material 10 can be reduced, thereby increasing the thermal conductivity of the composite material 10. be able to. A particularly desirable lower limit for AL1 is 0.15 mm.

The upper limit of AL1 is not limited, and is preferably 1 mm. When AL1 is 1 mm or less, the carbon particles 1 are placed in the strip 7A of the metal foil 7 in a state where the longest axis direction of the carbon particles 1 in the coated surface 7a of the strip 7A of the metal foil 7 is relatively random. As a result, the anisotropy of the physical properties (eg, thermal conductivity, linear expansion coefficient) of the composite material 10 in the planar direction can be reliably alleviated.

When scaly graphite particles are used as the carbon particles 1, the average aspect ratio (AL1/AL2) of the scaly graphite particles is not limited. Here, since the thermal conductivity of the scaly graphite particles is generally higher when the aspect ratio of the scaly graphite particles is larger, the average aspect ratio of the scaly graphite particles is is preferably as large as possible, particularly 30 or more. A desirable upper limit of the average aspect ratio is not limited, and is 100, for example.

When carbon fibers are used as the carbon particles 1, the fiber diameter of the carbon fibers is not limited, and the average fiber diameter of the carbon fibers is, for example, 0.1 nm to 20 μm. When the carbon fiber is at least one of PAN-based carbon fiber and pitch-based carbon fiber, the carbon fiber is preferably at least one of chopped fiber and milled fiber and has an average fiber diameter of 5 to 15 μm. When the carbon fibers are vapor-grown carbon fibers, their average fiber diameter is, for example, 0.1 nm to 20 μm.

The binder 2 provides the carbon particles 1 with binding strength to the strip material 7A of the metal foil 7. As shown in FIG. The type of binder 2 is not limited, and resin is usually used as binder 2 . Preferably, at least one selected from the group consisting of polyethylene oxide, polyvinyl alcohol and acrylic resin is used as the binder 2 . In this case, the binding of the carbon particles 1 to the strips 7A of the metal foil 7 can be reliably ensured, and further, the residual binder 2 in the composite material 10 can be reliably suppressed.

A solvent 3 dissolves the binder 2 . The type of the solvent 3 is not limited, and specifically, a hydrophilic solvent (eg, isopropyl alcohol, water), an organic solvent, or the like is used as the solvent 3 .

As shown in FIG. 2, the carbon particles 1, the binder 2 and the solvent 3 are placed in a mixing vessel 4a and stirred and mixed by a stirring mixer 4b. As a result, a coating liquid 5 containing the carbon particles 1, the binder 2 and the solvent 3 in a mixed state is prepared. It is desirable that the carbon particles 1 are uniformly dispersed in the coating liquid 5 . When preparing the coating liquid 5, predetermined additives such as a dispersant (not shown) and a surface conditioner (not shown) are added to the coating liquid 5 as necessary.

A disper, a planetary mixer, a bead mill, or the like is used as the stirring mixer 4b.

As shown in FIG. 2, in the coating/drying step S2, an unwinding roll 23 for unwinding a strip 7A of the metal foil 7 as a web (that is, a long metal foil 7) and a strip 7A of the metal foil 7 ( A roll-to-roll type coating dryer 20 using a winding roll 24 for winding the strip 8A of the carbon particle-coated foil 8 causes the coating liquid 5 to pass through the strip 7A of the metal foil 7 (specifically, It is coated in layers continuously in the longitudinal direction on the intended coating surface 7a) of the strip 7A of the metal foil 7 and dried.

The coating dryer 20 includes a bar coater 30 as coating means and a drying oven 21 as drying means. The bar coater 30 and the drying oven 21 are arranged side by side at an intermediate position in the flow direction F of the strip 7A of the metal foil 7 between the unwinding roll 23 and the winding roll 24 . The flow direction F of the strip material 7A of the metal foil 7 is the coating direction D of the coating liquid 5 (carbon particles 1) by the bar coater 30. As shown in FIG.

The bar coater 30 measures (doctors) and coats the coating liquid 5 onto the strip 7A of the metal foil 7, and is also called a rod coater.

The bar coater 30 includes a bar 33, a backup member 32, a coating liquid supply means 31 for supplying the coating liquid 5 to the bar 33, and the like.

Bar 33 has a predetermined gap width Gw and a predetermined gap depth Gd. In FIG. 2, the bar 33 extends the strip 7A of the metal foil 7 over its entire width direction on the side of the surface 7a to be coated of the strip 7A of the metal foil 7, that is, on the upper surface side of the strip 7A of the metal foil 7. arranged in a transverse manner.

The backup member 32 is arranged facing the bar 33 on the lower surface side of the strip 7A of the metal foil 7, and has a substantially flat plate shape in this embodiment.

As the bar 33, the bar 33A shown in FIG. 4 (which will be referred to as the "first type bar 33A" for convenience of explanation) and the bar 33B shown in FIG. ) is preferably used.

A bar 33A (see FIG. 4) of the first embodiment has spiral grooves 33a formed on the outer peripheral surface of the bar 33A at equal pitches in the axial direction of the bar 33B. More specifically, the bar 33A is formed by spirally winding a wire 35 having a circular cross section around a bar body (mandrel) 34a having a circular cross section with a gap (that is, gap winding) at regular pitches.

The spiral grooves 33a formed between the winding portions 35a of the wire 35 on the outer peripheral surface of the bar 33A form a gap between the strip 7A of the metal foil 7 and the bar body 34a. The width of the groove 33a in the axial direction of the bar 33A, that is, the width of the gap between the winding portions 35a of the wire 35 in the axial direction of the bar 33A is the gap width Gw, and the depth of the groove 33a in the radial direction of the bar 33A (i.e. , the diameter of the winding portion 35a of the wire 35) is the gap depth Gd.

The bar 33B of the second embodiment (see FIG. 5) has a plurality (more specifically, a large number) of annular grooves 33b formed on the outer peripheral surface of the bar 33B at equal pitches in the axial direction of the bar 33B. More specifically, the bar 33B includes a bar body (mandrel) 34b having a circular cross-section and a plurality of ring-shaped ring portions 36 extending in the axial direction of the bar body 34b (the bar 33B) with the bar body 34b inserted therein. are provided in a fixed state at equal pitches.

The annular groove 33b formed between the ring portions 36 on the outer peripheral surface of the bar 33B forms a gap between the strip 7A of the metal foil 7 and the bar body 34b. The width of the groove 33b in the axial direction of the bar 33B, that is, the width of the gap between the ring portions 36 in the axial direction of the bar 33B is the gap width Gw, and the depth of the groove 33b in the radial direction of the bar 33B is the gap depth Gd. be.

The width Rw of the ring portion 36 is not limited, and is usually set within the range of 0.2 to 1 mm.

Here, as the bar 33 of the bar coater 30, the bar 33C shown in FIG. 6 (for convenience of explanation, this will be referred to as the "third type bar 33C") is known. This bar 33C is formed by spirally winding a wire 35 having a circular cross section around a bar body (mandrel) 34c having a circular cross section without opening a gap (that is, by closed winding). Gw is 0 mm. However, this bar 33C cannot be used. The reason will be described later.

The coating liquid supply means 31 includes a coating liquid pan 31b as a coating liquid tank 31a containing the coating liquid 5, as shown in FIG. The coating liquid supply means 31 is configured so that the coating liquid 5 is continuously supplied to the bar 33 by storing the coating liquid 5 from the pan 31 b in the liquid reservoir 38 on the upstream side of the bar 33 . It is configured. In FIG. 2 , the liquid reservoir 38 consists of a corner between the strip 7A of the metal foil 7 on the upstream side of the bar 33 and the outer peripheral surface of the bar 33 . The upstream side of the bar 33 means the upstream side of the bar 33 with respect to the flow direction F of the strip 7A of the metal foil 7. As shown in FIG.

The drying oven 21 is installed downstream of the bar coater 30 (more specifically, the bar 33 of the bar coater 30), and the coating liquid 5 applied onto the strip 7A of the metal foil 7 by the bar coater 30 is dried. By heating and drying, liquid components such as the solvent 3 in the coating liquid 5 are removed by evaporation. The downstream side of the bar coater 30 (bar 33) means the downstream side of the bar coater 30 (bar 33) with respect to the flow direction F of the strip 7A of the metal foil 7. As shown in FIG.

In the coating/drying step S2, the strip 7A of the metal foil 7 unwound from the unwinding roll 23 is sent so as to sequentially pass through the bar coater 30 and the drying oven 21, and then wound up on the winding roll 24. .

When the strip 7A of the metal foil 7 passes the position of the bar 33 of the bar coater 30 substantially horizontally, the coating liquid 5 is applied to the strip 7A of the metal foil 7 (more specifically, the strip of the metal foil 7 is coated by the bar 33). It is metered and coated in layers continuously in the length direction over substantially the entire width direction of the surface 7a) of the material 7A to be coated.

When the strip 7A of the metal foil 7 passes through the drying furnace 21, liquid components such as the solvent 3 in the coating liquid 5 are removed by evaporation. As a result, a strip 8A of the carbon particle-coated foil 8, in which the carbon particles 1 are coated on substantially the entirety of the strip 7A of the metal foil 7, is obtained. Then, the strip 8A of the coated foil 8 is wound around the winding roll 24. As shown in FIG.

Next, the definition of the gap width Gw and the gap depth Gd of the bar 33 will be explained below.

The gap width Gw of the bar 33 must be 1.5 times or more the average length AL1 of the carbon particles 1 in the longest axial direction (that is, Gw≧1.5×AL1).

If Gw is not defined as described above, the carbon particles 1 in the coating liquid 5 are placed in the gap of the bar 33 ( It is difficult for the strip 7A of the metal foil 7 to pass through the groove 33a of the bar 33A and the groove 33b of the bar 33B of the second form from the upstream side to the downstream side in the flow direction F, so that the strip 7A of the metal foil 7 and the bar Clogging of the carbon particles 1 at the contact portion C with 33 is likely to occur.

When the clogging of the carbon particles 1 occurs, coating streaks are formed along the flow direction F on the strip 7A of the metal foil 7. As shown in FIG. In the state where coating streaks are generated, the state of dispersion of the carbon particles 1 on the strip 8A of the coated foil 8 is non-uniform. Therefore, when the metal-carbon particle composite material 10 is manufactured using such a coated foil 8, the uniformity of the physical properties of the composite material 10 in the planar direction may be impaired.

On the other hand, when Gw is defined as described above, the carbon particles 1 in the coating liquid 5 are in the gap of the bar 33 (the groove 33a of the bar 33A of the first form, the groove 33b of the bar 33B of the second form). passes reliably from the upstream side to the downstream side in the flow direction F of the strip 7A of the metal foil 7, so that clogging of the carbon particles 1 can be suppressed. As a result, the dispersion state of the carbon particles 1 on the strip 8A of the coated foil 8 can be made uniform.

In addition, in the downstream portion of the position of the winding portion 35 a of the bar 33 or the ring portion 36 on the strip 7 A of the metal foil 7 , the coating liquid 5 immediately after passing through the gap of the bar 33 . By spreading on the strip 7A of the foil 7 in the width direction of the strip 7A, the coating streak caused by the winding portion 35a or the ring portion 36 disappears.

A third form of bar 33C (see FIG. 6) cannot be used because Gw is not defined as described above. Furthermore, although not shown, a bar having no grooves on its outer peripheral surface (that is, a flat bar) cannot be used because Gw is not defined as described above.

A particularly desirable lower limit of Gw is three times the average length AL1 of the carbon particles 1 in the longest axial direction.

The upper limit of Gw is not limited, and is preferably 100 mm. When Gw is 100 mm or less, it is possible to reliably suppress breakage of the strip 7A of the metal foil 7 due to the pressure applied to the contact portion C between the strip 7A of the metal foil 7 and the bar 33 . A particularly desirable upper limit for Gw is 50 mm, and a more desirable upper limit is 10 mm.

Although the gap depth Gd of the bar 33 is not limited, it is preferably more than 1 times the average length AL2 of the carbon grains 1 in the shortest axial direction (that is, Gd>1×AL2). In this case, clogging of the carbon particles 1 at the contact portion C between the strip 7A of the metal foil 7 and the bar 33 can be reliably suppressed.

Therefore, for example, when scale-like graphite particles having an average length AL1 in the longest axial direction of 0.15 mm and an average aspect ratio (AL1/AL2) of 30 are used as the carbon particles 1, Gw is It must be 0.225 mm or greater, and since AL2 is 0.005 mm, Gd should be greater than 0.005 mm (ie, Gd>1×AL2). Furthermore, it is particularly desirable that the upper limit of Gd is 2 mm (that is, Gd≦400×AL2). When Gd is 2 mm or less, it is possible to reliably suppress breakage of the strip 7A of the metal foil 7 due to the pressure applied to the contact portion C between the strip 7A of the metal foil 7 and the bar 33 . A more desirable upper limit of Gd is 1 mm (that is, Gd≦200×AL2). A desirable lower limit for Gd is more than 0.005 mm (ie, Gd>1×AL2) as described above, and a particularly desirable lower limit for Gd is 0.3 mm (ie, Gd≧60×AL2).

When the coating liquid 5 is applied by the bar coater 30, the bar 33 may or may not be rotated around its axis. In particular, it is desirable to rotate the bar 33 . In this case, the carbon particles 1 that are about to clog at the contact portion C pass through the gaps (33a, 33b) of the bar 33, which contributes to the suppression of clogging of the carbon particles 1. When the bar 33 is rotated, the direction of rotation of the bar 33 may be the same as or opposite to the flow direction F of the strip 7A of the metal foil 7. As shown in FIG.

When the coating liquid 5 is prepared, the carbon particles 1 passed through a sieve having a predetermined mesh size are used as the carbon particles 1 contained in the coating liquid 5, so that excessively large carbon particles are coated. It is desirable not to include it in the working solution 5 . In this case, clogging of the carbon particles 1 can be reliably suppressed.

The viscosity of the coating liquid 5 is not limited, and is preferably 1000 to 20000 mPa·s at 25°C.

When the viscosity of the coating liquid 5 is 1000 mPa·s or more, the viscosity is relatively high, so sedimentation of the carbon particles 1 in the coating liquid tank 31a such as the coating liquid pan 31b can be reliably suppressed.

When the viscosity of the coating liquid 5 is 20000 mPa·s or less, the coating liquid 5 spreads over the strip 7A of the metal foil 7 in the width direction of the strip 7A immediately after passing through the gap of the bar 33. Since it spreads reliably, the occurrence of coating streaks due to the winding portion 35a of the bar 33 or the ring portion 36 can be reliably suppressed. Therefore, the carbon particles 1 can be uniformly dispersed on the strip 8A of the coated foil 8 without fail.

The amount of carbon particles applied onto the strip 7A of the metal foil 7 by the bar coater 30 is not limited, and is set in the range of 1 to 100 g/m ² , for example.

As shown in FIG. 7, in the step S3 of forming the laminate 9, first, the strip 8A of the coating foil 8 unwound from the take-up roll 24 is cut into a predetermined shape (eg, substantially rectangular shape) by a cutting machine 29. do. As a result, the coated foil 8 having a predetermined shape (for example, a substantially rectangular shape) is cut out from the strip 8A of the coated foil 8 . That is, the coated foil 8 is made up of cut pieces obtained by cutting the strip material 8A of the coated foil 8 .

Then, as shown in FIG. 8, a plurality of coating foils 8 are laminated. Thereby, a laminated body 9 in which a plurality of coated foils 8 are laminated is formed. The laminate 9 is used as a preform (sintered material).

The number of laminated coating foils 8 for forming the laminated body 9 is not limited, and is set according to the desired thickness of the composite material 10, and is, for example, 10 to 10,000.

In the sintering step S4, the laminated body 9 is sintered by heating it in a predetermined sintering atmosphere with a predetermined sintering device, thereby joining and integrating a plurality of coating foils 8 (in detail, sintering unify). A non-oxidizing atmosphere (including vacuum) or the like is applied as the sintering atmosphere.

A method for sintering the laminate 9 is selected from a vacuum hot press method, a discharge plasma sintering method, a hot isostatic sintering method (HIP method), an extrusion method, a rolling method, and the like. The discharge plasma sintering method is also called pulse current sintering method.

Specifically, as shown in FIG. 9, for example, the laminate 9 is placed in a sintering chamber 41 of a pressurized and heated sintering device (eg, vacuum hot press device, discharge plasma sintering device) 40 as a sintering device. are placed, and the laminate 9 is sintered by heating in a predetermined sintering atmosphere while pressurizing the laminate 9 in its thickness direction (that is, the lamination direction of the coated foil 8). As a result, the aforementioned metal-carbon particle composite material 10 shown in FIG. 10 is obtained.

The laminate 9 is pressed, for example, by pressing the laminate 9 in its thickness direction with a pair of pressing punches 42 provided in the sintering device 40 .

The heating temperature of the laminate 9 for sintering the laminate 9, that is, the sintering temperature of the laminate 9 is not limited, and is usually set to a temperature below the melting point of the metal material of the metal foil 7. , is preferably set to a temperature between the melting point of the metal material and a temperature about 50° C. lower than the melting point. In this case, the laminate 9 can be reliably sintered.

In the sintering step S4, the binder 2 present in the laminate 9 disappears by sublimation or thermal decomposition during the heating of the laminate 9 so that the temperature of the laminate 9 rises from approximately room temperature to the sintering temperature. removed from the body 9;

In the sintering step S4, by heating the laminate 9 as described above, part of the metal material of the metal foil 7 of each coating foil 8 permeates between the carbon particles 1 of each coating foil 8. The gaps between the carbon particles 1 substantially disappear. Furthermore, the metal material of the metal foil 7 of each coated foil 8 forms the metal matrix 13 and the carbon particles 1 of each coated foil 8 are dispersed in the metal matrix 13 .

Therefore, in the composite material 10, as described above, the metal layers 12 made of the metal matrix 13 and the carbon particle dispersed layers 11 in which the carbon particles 1 are dispersed in the metal matrix 13 in the plane direction of the composite material 10 are alternately laminated. They are joined and integrated (sintered and integrated) in a state where they are held together.

11 to 13 are diagrams for explaining a case where the laminate forming step S3 and the sintering step S4 are performed by a method different from the method described above.

In the laminated body forming step S3 shown in FIG. 11, the strip material 8A of the coating foil 8 unwound from the take-up roll 24 is wound a plurality of times in a roll shape to form a state in which the coating foil 8 is laminated. to form a laminate (roll body) 9A. In this laminate 9A, the radial direction corresponds to the lamination direction of the coated foil 8. As shown in FIG.

Next, as shown in FIG. 12, the laminate 9A is loaded into the container 51 of the extrusion device 50 so that the axial direction of the laminate 9A is parallel to the extrusion direction E of the extrusion device 50. Next, as shown in FIG. In addition, before loading the laminate 9A into the container 51, if necessary, the outer peripheral surface of the laminate 9A may be covered with a metal armor (not shown), or the axial direction of the laminate 9A may be covered. The end face may be covered with a metal lid (not shown). It is desirable that the materials of the exterior body and the lid body are the same as the metal material of the metal foil 7 .

Next, as shown in FIG. 13, while the laminate 9A is heated, the laminate 9A is pressed in the extrusion direction E by the stem 52 provided in the extrusion device 50, thereby causing the extrusion die 53 of the extrusion device 50 to move. The laminate 6A is pushed into the extrusion molding hole 54 and extruded from the extrusion molding hole 54. - 特許庁The laminated body 9A is sintered while being pressed in the radial direction of the laminated body 9A (that is, the lamination direction of the coating foil 8) when passing through the extrusion hole 54. As shown in FIG. As a result, a rod-shaped metal-carbon particle composite material 10A is obtained.

In this composite material 10A, the carbon particles 1 present in the composite material 10A are dispersed in the metal matrix of the composite material 10A in a state of being oriented in the axial direction of the composite material 10A (that is, the extrusion direction E of the laminate 9A). there is

In the coating/drying step S2 described above, the bar coater 30 is not limited to the configuration shown in FIG.

A bar coater 30A shown in the figure includes the above-described bar 33 and a coating liquid supply means 31A.

The coating liquid supply means 31A includes an applicator roll 31d, a coating container 31c, and the like. The bar 33 is supported from below by a support member 31e. The applicator roll 31d, bar 33 and support member 31e are arranged in the coating vessel 31c.

A supply pipe 31f for supplying the coating liquid 5 into the coating container 31c and a discharge pipe 31g for discharging the coating liquid 5 in the coating container 31c are connected to the coating container 31c. Reference numeral "39" is a pressing roll.

In this bar coater 30A, the coating liquid 5 in the coating container 31c is first applied by the rotating applicator roll 31d to the strip material 7A of the metal foil 7 (more specifically, the strip material 7A of the metal foil 7 is scheduled to be coated). It is applied in a thick layer on the surface 7a). In the figure, the surface to be coated 7a is the lower surface of the strip 7A of the metal foil 7. As shown in FIG.

Next, the coating liquid 5 applied onto the strip 7A of the metal foil 7 is metered and coated by the bar 33. As shown in FIG. At this time, the bar 33 may or may not be rotated about its axis. When the bar 33 is rotated, the direction of rotation of the bar 33 may be the same as or opposite to the flow direction F of the strip 7A of the metal foil 7. As shown in FIG.

Therefore, in the present embodiment, the uniform dispersion state of the carbon particles 1 on the coated foil 8 is achieved as described above, so that the metal-carbon particle composite produced using the coated foil 8 The material 10 (see FIG. 10) has highly uniform physical properties (eg, thermal conductivity, coefficient of linear expansion) in the planar direction. Therefore, it has high reliability against temperature changes such as thermal cycles.

Therefore, as shown in FIG. 15, the composite material 10 is suitable as a material for at least one of the plurality of constituent members constituting a cooler 60 that cools a heating element (indicated by a two-dot chain line) 66. can be used for

The cooler 60 includes, for example, a wiring layer 61, an insulating layer 62, a buffer layer 63, and a heat radiation member (including a cooling member) 64 as a plurality of constituent members. These are laminated in this order and joined together by a predetermined joining means (for example, brazing) to form the cooler 60 .

Examples of the heating element 66 include heat-generating elements (including semiconductor elements) such as power module chips. If the heating element 66 is a power module chip, the cooler 60 is a power module cooler. Furthermore, the cooler 60 is used by being mounted on a vehicle such as a hybrid vehicle (HEV), an electric vehicle (EV), or a train, or used as a battery cooler or the like in the energy field such as wind power generation or solar power generation. .

A heating element 66 is mounted on the mounting surface 61a, which is the upper surface of the wiring layer 61, by soldering with a solder layer (indicated by a two-dot chain line) 67. As shown in FIG. The insulating layer 62 has electrical insulation and is usually made of ceramic. The buffer layer 63 is a layer for relaxing stress such as thermal stress generated in the cooler 60 . The heat dissipation member 64 is a member for cooling the heat generating element 66 by dissipating heat conducted from the heat generating element 66 through the wiring layer 61, the insulating layer 62 and the buffer layer 63. For example, as shown in FIG. It consists of a heat sink having a plurality of heat radiation fins 64a on the inside.

In the present invention, the heat radiating member 64 is not limited to a heat sink, and may be, for example, a heat radiating plate or a liquid cooling type cooling member provided with a coolant flow passage inside. It can be.

In the above-described cooler 60, more specifically, among the above-described plurality of constituent members 61 to 64, the constituent members excluding the insulating layer 62 (that is, the wiring layer 61, the buffer layer 63, and the heat dissipation member 64) are selected from the group. at least one of which is made of the composite material 10 of the present embodiment. Therefore, the cooler 60 has high reliability (eg, high bonding reliability) against temperature changes such as thermal cycles.

Here, in the present invention, the composite material 10 is not limited to the material used as the material for the cooler 60 described above, and may also be a material for lighting fixtures, a material for portable/mobile terminals, a material for heat spreaders, It can also be used as a material for battery modules.

Although several embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be variously modified without departing from the gist of the present invention.

In the present invention, the metal foil to which the coating liquid is applied is desirably the strip 7A of the metal foil 7 (that is, the long belt-shaped metal foil 7) as shown in the above embodiment. In addition, it may be, for example, a metal foil that is not strip-shaped (for example, a substantially square-shaped metal foil having preset length and width dimensions).

Moreover, in the present invention, the foil to which the coating liquid is applied is not limited to a metal foil, and may be a foil other than a metal foil, such as a plastic foil.

Furthermore, in the present invention, the particles are not limited to carbon particles, but may be particles other than carbon particles, such as ceramic particles. When the particles are ceramic particles, boron nitride particles, aluminum nitride particles and the like are used as the ceramic particles.

Further, the particle-coated foil obtained by the method for producing a particle-coated foil according to the present invention is used as an intermediate material for producing a functional material such as a metal-carbon particle composite material as shown in the above embodiment. Alternatively, the particle-coated foil itself may be used as a functional material.

Specific examples and comparative examples of the present invention are shown below. However, the present invention is not limited to the following examples.

<Example 1>
A container for mixing flaky graphite particles as carbon particles, a 10% by mass aqueous solution of polyethylene oxide and a 10% by mass aqueous solution of polyvinyl alcohol as binders, isopropyl alcohol and water as solvents, a dispersant, and a surface conditioner. A coating solution was prepared by putting the mixture inside and stirring and mixing with a disper. The viscosity of the coating liquid was 5000 mPa·s at 25°C.

The scale-like graphite particles had an average length AL1 in the longest axial direction of 0.15 mm, an average aspect ratio (AL1/AL2) of 30, and an average length AL2 of the shortest axial direction of 0.005 mm. rice field. The content of the flake-like graphite particles contained in the coating liquid was 90% by mass with respect to the total weight of the binder and the flake-like graphite particles.

The coating solution was applied onto a strip of aluminum foil (Al foil) using a bar coater of a roll-to-roll type coating dryer, and dried at a drying temperature of 130° C. in the drying furnace of the coating dryer. In this way, strips of scale-like graphite particle-coated foil were produced. The coating amount of the scale-like graphite particles of the coated foil was 20 g/m ² .

The material of the aluminum foil was JIS (Japanese Industrial Standards) aluminum alloy number 1N30, and its thickness was 20 μm and its width was 300 mm. The surface to be coated of the strip of aluminum foil to which the coating liquid was applied was the upper surface of the strip of aluminum foil. The coating speed of the coating liquid by the bar coater (that is, the flow speed of the strip of aluminum foil) was 1 m/min.

The configuration of the bar coater was as follows.

The bar 33A shown in FIG. 4 was used as the bar of the bar coater. The gap width Gw of the bar 33A was 0.225 mm, and the diameter of the winding portion 35a of the wire 35, that is, the gap depth Gd was 0.51 mm. Therefore, Gw was 1.5 times higher than AL1.

Next, the strip of the coated foil was cut into squares (size: 50 mm long×50 mm wide), and a plurality of square coated foils were cut out from the strip of the coated foil. Then, a laminate was formed by laminating 200 coated foils.

Then, the laminate is heated under predetermined sintering conditions while being pressurized in the thickness direction (that is, the lamination direction of the coated foil) in a vacuum atmosphere by a discharge plasma sintering apparatus as a pressurized and heated sintering apparatus. The laminate was sintered by As a result, an aluminum-flaky graphite particle composite material was obtained as a metal-carbon particle composite material. The thickness of the composite was approximately 5 mm.

The sintering conditions were as follows.

The sintering temperature was 620° C., the holding time of the sintering temperature (that is, the sintering time) was 3 hours, the rate of temperature increase from room temperature was 20° C./min, the pressure applied to the laminate was 20 MPa, and the degree of vacuum was 3 Pa. rice field. Moreover, the binder was removed from the laminate by temporarily stopping the temperature rise during the heating of the laminate from room temperature to the sintering temperature of 620°C. The binder removal conditions applied at this time were as follows.

The heating temperature of the laminate for removing the binder was 450° C., and the holding time was 30 minutes.

The sintered state of the composite was good. Furthermore, in the composite material, aluminum as a metal matrix is sufficiently penetrated between flake graphite particles, there are almost no voids inside the composite material, and the density of the composite material is less than the theoretical density of the composite material. 99%.

Moreover, the thermal conductivity in the plane direction of the composite material was 380 W/(m·K), which was higher than that of aluminum. The above thermal conductivity is a value at 20° C. (same below).

When the composite material was used as the material for the wiring layer, the buffer layer and the heat radiating member of the power module cooler, the cooler was manufactured, and the cooler had high cooling performance.

<Example 2>
An aluminum-flaky graphite particle composite material was produced in the same manner as in Example 1 above, except that the bar coater bar gap width Gw was 0.45 mm. The coating amount of the scale-like graphite particles of the coated foil was 25 g/m ² . Gw was 3-fold relative to AL1.

The sintered state of the composite was good. Furthermore, in the composite material, aluminum as a metal matrix is sufficiently penetrated between flake graphite particles, there are almost no voids inside the composite material, and the density of the composite material is less than the theoretical density of the composite material. 99%.

Moreover, the thermal conductivity in the plane direction of the composite material was 410 W/(m·K), which was higher than that of aluminum.

When the composite material was used as the material for the wiring layer, the buffer layer and the heat radiating member of the power module cooler, the cooler was manufactured, and the cooler had high cooling performance.

<Example 3>
Same as Example 1 above except that the average length AL1 of the longest axis of the flake graphite particles is 0.30 mm (its average aspect ratio is 30) and the gap width Gw of the bars of the bar coater is 50 mm. to produce an aluminum-flaky graphite particle composite. The coating amount of the scale-like graphite particles of the coated foil was 25 g/m ² . The bar gap width Gw of the bar coater was 167 times that of AL1.

The sintered state of the composite was good. Furthermore, in the composite material, aluminum as a metal matrix is sufficiently penetrated between flake graphite particles, there are almost no voids inside the composite material, and the density of the composite material is less than the theoretical density of the composite material. 99%.

Moreover, the thermal conductivity in the plane direction of the composite material was 440 W/(m·K), which was higher than that of aluminum.

When the composite material was used as the material for the wiring layer, the buffer layer and the heat radiating member of the power module cooler, the cooler was manufactured, and the cooler had high cooling performance.

<Example 4>
Carbon fibers as carbon particles, 10% by weight aqueous solution of polyethylene oxide and 10% by weight aqueous solution of polyvinyl alcohol as binders, isopropyl alcohol and water as solvents, a dispersant, and a surface conditioner are placed in a mixing container. were added and mixed by stirring with a disper to prepare a coating liquid. The viscosity of the coating liquid was 5000 mPa·s at 25°C.

The average length AL1 of the longest axial direction of the carbon fibers is 0.15 mm, and the average aspect ratio (AL1/AL2) thereof is 15, so the average length of the shortest axial direction (i.e. the average fiber diameter of the carbon fibers) AL2 was 0.01 mm. The content of carbon fibers contained in the coating liquid was 90% by mass with respect to the total mass of the binder and carbon fibers.

Next, using the coating liquid, an aluminum-carbon fiber composite material as a metal-carbon particle composite material was produced in the same manner as in Example 1 above. The carbon fiber coating amount of the coated foil was 20 g/m ² . The bar gap width Gw of the bar coater was 1.5 times that of AL1.

The sintered state of the composite was good. Furthermore, in the composite material, aluminum as a metal matrix penetrates sufficiently between the carbon fibers, there are almost no voids inside the composite material, and the density of the composite material is 99% of the theoretical density of the composite material. Met.

Moreover, the thermal conductivity in the plane direction of the composite material was 280 W/(m·K), which was higher than that of aluminum.

When the composite material was used as the material for the wiring layer, the buffer layer and the heat radiating member of the power module cooler, the cooler was manufactured, and the cooler had high cooling performance.

<Example 5>
A copper-flaky graphite particle composite material was produced as a metal-carbon particle composite material in the same manner as in Example 2 above, except that a copper foil (Cu foil) was used as the metal foil. The thickness of the copper foil was 30 μm and its width was 500 mm. The coating amount of the scale-like graphite particles of the coated foil was 20 g/m ² . The bar gap width Gw of the bar coater was three times that of AL1.

The sintering conditions were as follows.

The sintering temperature was 900°C, the holding time of the sintering temperature (that is, the sintering time) was 3 hours, the rate of temperature increase from room temperature was 20°C/min, the pressure applied to the laminate was 20 MPa, and the degree of vacuum was 3 Pa. rice field. In addition, the binder was removed from the laminate by temporarily stopping the temperature rise during the heating of the laminate from room temperature to the sintering temperature. The binder removal conditions applied at this time were as follows.

The heating temperature of the laminate for removing the binder was 450° C., and the holding time was 30 minutes.

The sintered state of the composite was good. Furthermore, in the composite material, copper as a metal matrix sufficiently penetrates between the scale-like graphite particles, there are almost no voids inside the composite material, and the density of the composite material is less than the theoretical density of the composite material. 99%.

Moreover, the thermal conductivity in the plane direction of the composite material was 460 W/(m·K), which was higher than that of aluminum.

When the composite material was used as the material for the wiring layer, the buffer layer and the heat radiating member of the power module cooler, the cooler was manufactured, and the cooler had high cooling performance.

<Comparative Example 1>
An attempt was made to produce an aluminum-scale graphite particle composite material in the same manner as in Example 1 above, except that the bar coater bar gap width Gw was 0.15 mm. As a result, clogging of the flake-like graphite particles occurred at the point of contact between the aluminum foil and the bar immediately after the start of coating, and coating could not be carried out continuously. Note that in this case, Gw was 1 times that of AL1.

The results of Examples 1 to 5 and Comparative Example 1 are shown in Table 1.

In the "sintered state" column in Table 1, "○" means that the sintered state of the composite material was good.

In the "coating amount", "sintered state" and "thermal conductivity" columns, "-" means that it was impossible to measure or evaluate because coating could not be performed continuously. there is

INDUSTRIAL APPLICABILITY The present invention is applicable to a method for producing a particle-coated foil in which particles are coated on a foil and a method for producing a metal-particle composite.

1: Carbon particles 2: Binder 3: Solvent 5: Coating liquid 7: Metal foil 7A: Metal foil strip 8: Carbon particle coated foil 8A: Carbon particle coated foil strip 9: Laminate 10: Metal - Carbon particle composite material 11: carbon particle dispersion layer 12: metal layer 13: metal matrix 20: coating dryer 21: drying ovens 30, 30A: bar coater 33: bar

Claims (7)

A method for producing a particle-coated foil in which particles are coated on the foil,
Including a step of applying a coating liquid containing particles, a binder and a solvent for the binder on the foil and drying it,
In the step of coating and drying, the coating solution is applied onto the foil by a bar coater having a bar with a gap width of 1.5 times or more the average length of the particles in the longest axial direction. A method for producing a particle-coated foil. 2. The method for producing a particle-coated foil according to claim 1, wherein scale-like graphite particles are used as said particles. 2. The method for producing a particle-coated foil according to claim 1, wherein carbon fibers are used as said particles. The method for producing a particle-coated foil according to any one of claims 1 to 3, wherein at least one selected from the group consisting of polyethylene oxide, polyvinyl alcohol and acrylic resin is used as the binder. The method for producing a particle-coated foil according to any one of claims 1 to 4, wherein a metal foil is used as the foil. 6. The method for producing a particle-coated foil according to claim 5, wherein said metal foil is an aluminum foil. a step of forming a laminate in which a plurality of particle-coated foils obtained by the method for producing a particle-coated foil according to claim 5 or 6 are laminated;
and sintering the laminate.

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