JP2014079927A - Heat-dissipating member and method for manufacturing heat-dissipating member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-dissipating member that has good heat-dissipating properties.SOLUTION: A heat-dissipating member (1) is provided with: a base sheet (2) having a porous matrix, which comprises a fluorine resin and a heat-conducting filler, as the base; and multiple adhesive sections (3) disposed on one of the main surfaces of the base sheet (2), the sections being separated from each other. The fluorine resin of the base sheet (2) comprises polytetrafluoroethylene. The area of the one main surface of the base sheet (2) that is covered by the multiple adhesive sections (3) is 10-85% of the area of the one main surface of the base sheet (2). On the one main surface of the base sheet (2), the multiple adhesive sections (3) are disposed so as to form passageways (5) that are continuous from one edge of the base sheet to the other edge.

Description

  The present invention relates to a heat radiating member, and more particularly to a heat radiating member suitable for bonding to a heating element in an environment where a fluid such as oil is present.

  In recent years, hybrid vehicles and electric vehicles have been developed from the viewpoint of environmental friendliness. A motor is used for such a vehicle drive system, and a high output of the motor is required. In order to increase the output of the motor, it is necessary to improve the cooling performance to cope with the increase in the heat generation amount accompanying the improvement in output.

  As a method for improving the cooling performance of the vehicle motor, the use of a heat radiating member can be considered. As a heat radiating member, a member in which a heat conductive filler is dispersed in a resin matrix is known. Here, automatic transmission fluid (ATF) is sealed as lubricating oil in the lower part of the motor. Therefore, in the heat dissipating member used for the motor, the resin matrix is required to have oil resistance. .

  A fluororesin is known as a resin having oil resistance, and a heat radiating member in which a heat conductive filler is dispersed in a fluororesin matrix is also conventionally known (see, for example, Patent Document 1). Conventional heat radiating members in which a heat conductive filler is dispersed in a fluororesin matrix are mainly used for electronic devices.

  As a method for attaching the heat radiating member to the heating element, there is proposed a method of bonding an electronic device such as a power transistor and a heat sink by providing an adhesive layer on a base sheet, although it is used for electronic components (Patent Document). 2). Specifically, a thermally conductive adhesive sheet having an adhesive layer formed in a dot shape or a mesh shape and configured such that the base sheet is in direct contact with the heating element and the heat sink has been proposed. Further, it has been proposed to increase the area where the base sheet is in direct contact with the heating element and the heat sink by using silicone rubber that exhibits fluidity at room temperature as the base sheet.

JP 2008-208159 A JP 2001-110965 A

  As described in Patent Document 2, when a low-rigidity base material sheet such as silicone rubber is used, the base material sheet comes into contact with the heating element, so that it is difficult for fluid to flow between the base material sheet and the heating element. When a heat radiating member is provided for cooling the vehicle motor, if the fluid such as oil flows easily through the gap between the heat radiating member and the heat generating element, the fluid between the heat radiating member and the heat generating element. It is considered that heat dissipation from the vehicle motor is promoted by this flow. Thereby, it is thought that the heat dissipation characteristic of a heat radiating member improves.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat radiating member that is used for cooling a motor for a vehicle and has good heat radiating characteristics.

The present invention
A base material sheet based on a porous base material containing a fluororesin and a heat conductive filler;
A plurality of adhesive portions disposed away from each other on one main surface of the base sheet,
The fluororesin comprises polytetrafluoroethylene,
The area where the plurality of adhesive portions cover one main surface of the base sheet is 10% to 85% of the area of one main surface of the base sheet,
Provided is a heat dissipating member in which the plurality of adhesive portions are arranged so that a continuous path from one end to the other end of the base sheet is formed on one main surface of the base sheet.

  The present invention also provides a step (1) of obtaining a rolled laminated sheet by laminating and rolling a plurality of sheet-like molded bodies containing a polytetrafluoroethylene-containing fluororesin, a heat conductive filler, and a molding aid. A step (2) of obtaining the base sheet by removing the molding aid from the rolled laminated sheet, and a step of forming a plurality of adhesive portions by applying an adhesive material to one main surface of the obtained base sheet ( The manufacturing method of the heat radiating member including 3) is provided.

  According to the present invention, since the base material is a fluororesin having a relatively high rigidity (Young's modulus), the base material sheet is less likely to come into direct contact with the heating element. Moreover, the some adhesion part is arrange | positioned so that the channel | path which follows from one end of a base material sheet to the other end may be formed in one main surface of the said base material sheet. Accordingly, fluid such as oil easily flows between the base sheet and the heating element on one main surface of the base sheet. Therefore, the heat dissipation characteristics of the heat dissipation member can be improved.

Top view of one embodiment of heat dissipation member Sectional drawing along the VV line of FIG. 1A Top view of other embodiment of heat dissipation member Sectional drawing along the XX line of FIG. 2A Front view of the thermal property evaluation apparatus used in the examples Side view of the thermal property evaluation apparatus used in the examples A graph showing the relationship between the thermal resistance of the heat dissipation member and the coverage of the adhesive part

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by the following embodiment.

  As shown in FIG. 1A or FIG. 1B, the heat radiating member 1 includes a base sheet 2 and a plurality of adhesive portions 3 arranged on one main surface of the base sheet 2 so as to be separated from each other. The base material sheet 2 uses a porous base material containing a fluororesin and a heat conductive filler as a base material. As shown in FIG. 1B, a passage 5 is formed between the adjacent adhesive portions 3 in the heat radiating member 1. The passage 5 is a passage that is continuous from one end 2A to the other end 2B of the base sheet 2 on one main surface of the base sheet 2. The adhesive portions 3 are arranged in a dispersed manner so that such a passage 5 is formed on one main surface of the base sheet 2. When attaching to the heating element, the heat radiating member 1 and the heating element are joined via the adhesive portion 3.

  The heat radiating member 1 is provided with high oil resistance by using a porous base material containing a fluororesin as the base material sheet 2. Moreover, since the base material sheet 2 uses the porous preform | base_material containing a fluororesin as a base material, the base material sheet 2 shows comparatively high rigidity (Young's modulus). Therefore, when the heat radiating member 1 is attached to a heat generating body and the base material sheet 2 is subjected to stress, the base material sheet 2 is difficult to directly contact the heat generating body. For example, when the heating element is a motor for a vehicle, oil used for motor lubrication easily flows between the base sheet 2 and the heating element through the passage 5. For this reason, since heat is radiated from the motor by the flow of oil passing through the passage 5, the heat radiating member 1 can exhibit high heat dissipation characteristics.

  The fluororesin of the porous base material that is the base sheet 2 contains polytetrafluoroethylene (PTFE). When the fluororesin contains PTFE, it becomes easy to produce a porous base material containing a heat conductive filler at a high content. The fluororesin of the base sheet 2 may contain a fluororesin other than PTFE. Examples of fluororesins other than PFTE include meltable fluororesins. When the fluororesin contains a meltable fluororesin, it becomes easier to produce a porous base material containing a heat conductive filler at a high content. For example, a material containing a fluororesin and a heat conductive filler is made into a sheet. It becomes easy. As the meltable fluororesin, it is preferable to use at least one selected from the group consisting of perfluoroalkoxy fluororesin (PFA) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). PFA and FEP include various products having different melting points, and may be appropriately selected depending on the processing method and processing conditions for the porous base material.

Regarding the ratio of the meltable fluororesin to the fluororesin, the lower limit is preferably 5% by mass or more, more preferably 10% by mass or more, and the upper limit is preferably 70% by mass or less, more preferably 50% by mass. Hereinafter, it is more preferably 30% by mass or less.

The heat radiating member 1 is given high thermal conductivity by the heat conductive filler. Here, the heat conductive filler means a filler having a thermal conductivity of 1 W / mK or more, preferably 100 W / mK or more. The type of the heat conductive filler may be appropriately selected according to the use of the heat radiating member 1. For example, when it is desired to impart high insulation to the heat dissipating member 1, an insulating filler having a volume resistivity of 10 ¹⁴ Ω · cm or more may be used, and preferably boron nitride, aluminum nitride, alumina, silicon nitride, And at least one insulating filler selected from the group consisting of magnesium oxide is used. In a hybrid vehicle motor, a generator, etc., there is a part where a high voltage and a large transient current are generated, and the heat dissipating member 1 provided with high insulation using an insulating filler is used in such a part. It is advantageous to use.

On the other hand, when it is desired to impart high conductivity to the heat radiating member 1, a conductive filler having a volume resistivity of 10 ⁶ Ω · cm or less may be used, and preferably graphite, carbon black, carbon fiber, metal fiber (example) , Aluminum fiber, copper fiber, etc.) and at least one conductive filler selected from the group consisting of metal particles (eg, particles of gold, silver, copper, palladium, platinum, etc.) is used.

  The shape of the heat conductive filler is not particularly limited, and spherical and non-spherical fillers can be used, and heat conduction anisotropy can be imparted by aligning in the in-plane direction by rolling. Scale-like is preferable. Further, for the same reason, it is preferable that the heat conductive filler itself has a heat conduction anisotropy. Moreover, when improving the heat conductivity of the thickness direction, you may use the heat conductive filler of the aggregation shape currently sold from each company.

  The heat conductive filler is not particularly limited as long as the heat conductive filler is supported on the fluororesin matrix without falling off, and sufficient heat conductivity can be imparted to the obtained heat radiating member. The thing of 0.2-500 micrometers is preferable, and the thing of 0.2-50 micrometers is more preferable. However, the heat conductive filler preferably has a larger particle size in order to achieve high heat conductivity. This is because even if the content of the heat conductive filler is the same, the larger the particle size, the smaller the number of interfaces, and the lower the thermal resistance. Here, the particle size is a value measured by a laser diffraction / scattering particle size / particle size distribution measuring device (eg, “Microtrack” manufactured by Nikkiso Co., Ltd.).

  The content of the heat conductive filler is preferably in the range of 50 to 95% by mass, more preferably in the range of 70 to 90% by mass, with respect to the total mass of the base sheet 2, and 80 to 90% by mass. More preferably, it is in the range. The content of the fluororesin is preferably in the range of 5 to 50% by mass, more preferably in the range of 10 to 30% by mass, and 10 to 20% by mass with respect to the total mass of the base sheet 2. More preferably, it is in the range.

  The base material sheet 2 may contain components other than a fluororesin and a heat conductive filler. Examples of such components include resins other than fluororesins, and as the resin, for example, commonly used thermoplastic resins and thermosetting resins can be used. The content of the component is preferably 10% by mass or less with respect to the total mass of the porous base material.

  When the rigidity (Young's modulus) of the base material sheet 2 is small, the base material sheet 2 is easily bent under stress, and the base material sheet 2 and the heating element are easily in direct contact. From this viewpoint, the Young's modulus of the base sheet 2 is, for example, 1 MPa or more, preferably 5 MPa or more, and more preferably 10 MPa or more. Here, “Young's modulus” refers to a value at 25 ° C. Moreover, when the thickness of the base material sheet 2 is small, the base material sheet 2 is easily bent under stress. From this viewpoint, the thickness of the base sheet 2 is, for example, 0.05 mm or more, and more preferably 0.1 mm or more. On the other hand, the thickness of the base material sheet 2 is 3 mm or less, for example, and 1 mm or less is preferable.

  The plurality of adhesive portions 3 are formed on one main surface of the base sheet 2 so as to partially cover one main surface of the base sheet 2. The ratio (coverage) of the area where the plurality of adhesive portions 3 cover the main surface with respect to the area of one main surface of the base sheet 2 affects the heat dissipation characteristics of the heat radiating member 1. Usually, a certain load is applied to the base material sheet 2. Therefore, when the coverage of the plurality of adhesive portions 3 decreases, the stress received by the plurality of adhesive portions 3 increases. Thereby, the adhesion part 3 is compressed more largely and the thickness of the adhesion part 3 becomes small. As a result, the thermal resistance of the adhesion part 3 falls and the thermal resistance of the heat radiating member 1 also falls. From this viewpoint, the area where the plurality of adhesive portions 3 cover one main surface of the base sheet 2 is preferably 85% or less of the area of one main surface of the base sheet 2, and more preferably 70% or less. Preferably, 45% or less is more preferable.

  According to the above description, it seems that the heat dissipation characteristics of the heat dissipation member 1 are improved as the coverage of the plurality of adhesive portions 3 is smaller. However, in practice, if the coverage of the plurality of adhesive portions 3 is too small, the heat resistance of the heat radiating member 1 is increased. Therefore, the area where the plurality of adhesive portions 3 cover one main surface of the substrate sheet 2 is preferably 10% or more, more preferably 13% or more, and more preferably 15% or more of the area of one main surface of the substrate sheet 2. Is more preferable. Thus, if the area which the some adhesion part 3 covers one main surface of the base material sheet 2 is defined, the thermal radiation member 1 shows a favorable thermal radiation characteristic.

  As will be described later, when the coverage is around 30%, the thermal resistance of the heat radiating member 1 is the smallest. From the viewpoint of reducing the amount of the adhesive material constituting the plurality of adhesive portions 3 while reducing the thermal resistance of the heat radiating member, the area where the plurality of adhesive portions 3 cover one main surface of the substrate sheet 2 is The area of one main surface of the sheet 2 is preferably less than 30%, particularly preferably 28% or less. From this viewpoint, the area where the plurality of adhesive portions 3 cover one main surface of the base sheet 2 is preferably 10% or more, more preferably 13% or more, and further preferably 15% or more.

  If the distance between the adjacent adhesive portions is small, the width of the passage 5 becomes too small, and the fluid hardly flows between the base sheet 2 and the heating element. Moreover, when the distance between the adjacent adhesion parts is large, it will become easy to bend the base material sheet 2, and it will become easy for the base material sheet 2 to contact a heat generating body directly. This makes it difficult for fluid to flow between the base sheet 2 and the heating element. From these viewpoints, the distance between adjacent adhesive portions is preferably 3 to 9 mm.

  As shown to FIG. 1A, the some adhesion part 3 may be arrange | positioned at dot shape. Here, “arranged in a dot shape” means that the adhesive portions 3 having a predetermined shape are arranged so as to be dispersed on one main surface of the base sheet 2. Here, the shape of the adhesive portion 3 may be circular, elliptical, triangular, polygonal, or the like in plan view. In order to reduce the resistance of the fluid flow between the base sheet 2 and the heating element, the shape of the adhesive portion 3 is preferably circular in plan view as shown in FIG. 1A. Moreover, as shown to FIG. 1A, the some adhesion part 3 may be arrange | positioned in the position corresponding to the lattice point of a square lattice. Thereby, the straight channel | path 5 is formed toward the other end 2B from the one end 2A of the base material sheet 2, and the flow resistance of the fluid which flows between the base material sheet 2 and a heat generating body is small. Further, the anisotropy of the peeling force of the heat radiating member 1 is unlikely to occur.

  2A and 2B, the heat radiating member 1 is formed in a linear shape in which a plurality of adhesive portions 3 extend in the same direction. When the plurality of adhesive portions 3 are formed in this way, a straight passage 5 is formed from one end 2A of the base sheet 2 to the other end 2B, and the fluid flows between the base sheet 2 and the heating element. The flow resistance is small.

  If the thickness of the adhesive part 3 is large, the thermal resistance of the adhesive part 3 increases and the thermal resistance of the heat radiating member 1 also increases. On the other hand, when the thickness of the adhesion part 3 is small, the base material sheet 2 tends to contact a heat generating body. From these viewpoints, the thickness of the adhesive portion 3 is, for example, 0.005 μm to 50 μm, preferably 0.01 μm to 20 μm, and more preferably 1 μm to 10 μm.

  Examples of the material used for the pressure-sensitive adhesive part 3 include pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives and silicone pressure-sensitive adhesives, and adhesives such as thermosetting adhesives (eg, epoxy resins) and hot-melt adhesives.

  Next, the manufacturing method of the heat radiating member 1 is demonstrated. The heat radiating member 1 of the present invention is a step (1) in which a rolled laminated sheet is obtained by laminating and rolling a plurality of sheet-like molded bodies containing PTFE-containing fluororesin, a heat-conducting filler, and a molding aid. A step (2) of obtaining a base material sheet which is a porous base material by removing the molding aid from the laminated sheet, and an adhesive material is applied to one main surface of the obtained base material sheet, and a plurality of adhesive parts It is preferably manufactured by a method including the step (3) of forming

  A plurality of sheet-like molded bodies containing PTFE-containing fluororesin, heat conductive filler, and molding aid used in step (1) are mixed with PTFE-containing fluororesin, heat conductive filler, and molding aid. A paste-like mixture can be prepared first and then formed into a sheet.

  The mixing of the fluororesin containing PTFE, the heat conductive filler, and the molding aid is desirably performed under conditions that suppress fiber formation of PTFE as much as possible. Specifically, it is desirable to reduce the number of rotations of the mixing device so as not to apply shear to PTFE, to shorten the mixing time, and to mix without kneading. If fiber formation occurs in the PTFE at the stage of mixing the materials, the PTFE fibers may be cut during rolling to destroy the PTFE network structure, and it is difficult to maintain the sheet shape. It may become.

  As the molding aid, for example, a saturated hydrocarbon such as dodecane or decane can be used. What is necessary is just to add a shaping | molding adjuvant so that it may become 20-55 mass% with respect to the total mass of a mixture.

  By molding these mixtures by extrusion molding, roll molding, or the like, a sheet-like molded body can be obtained. The thickness of the sheet-like molded body is, for example, 0.5 to 5 mm. A plurality of such sheet-like molded bodies are prepared.

Subsequently, the plurality of sheet-like molded bodies are overlapped (laminated) and rolled to obtain the base sheet 2. The number of the sheet-like molded bodies to be used is not particularly limited as long as it is 2 or more, and is appropriately determined in consideration of the number of layers of the sheet-like molded bodies constituting the final rolled laminated sheet to be the base sheet 2. What is necessary is just about 2-10 sheets. As described above, the manufacturing method includes rolling of the laminated body. By the lamination and rolling, the sheet strength can be improved and the heat conductive filler can be firmly fixed to the fluororesin matrix. A sheet having a high rate and flexibility can be manufactured.

  In the manufacturing method, after the step (1), a plurality of rolled laminated sheets of a sheet-like formed body are rolled and rolled, or at least one rolled laminated sheet of a sheet-like formed body, a fluororesin, and heat conduction It is preferable to further perform the step (1 ′) of superposing and rolling at least one sheet-like molded body containing a filler and a molding aid. This step is preferably repeated. At the beginning of rolling (the stage in which the number of layers of the sheet-shaped formed product is small), the sheet strength is low and it is difficult to withstand the high-magnification rolling. The heat conduction filler is more firmly fixed to the fluororesin matrix. In order to achieve high strength, it is desirable to roll the sheet-like formed body and the rolled laminated sheet of the sheet-like formed body two by two.

  Examples of embodiments of step (1) and step (1 ') will be described below. First, a plurality of (for example, 2 to 10) sheet-like molded bodies are prepared. Next, the plurality of sheet-like formed bodies are laminated, and the laminated body is rolled to obtain a rolled laminated sheet (first rolled laminated sheet) (step (1)). A plurality of (for example, 2 to 10) first rolled laminated sheets thus obtained are prepared and laminated, and the laminated body is rolled to obtain a rolled laminated sheet (second rolled laminated sheet) ( Step (1 ′)). A plurality of (for example, 2 to 10) second rolled laminated sheets obtained in this way are prepared and laminated, and the laminated body is rolled to obtain a rolled laminated sheet (third rolled laminated sheet) ( Repeat step (1 ′)). Further, a plurality of third rolled laminated sheets are prepared, laminated and rolled in the same manner, and the step (1 ′) is repeated until the number of constituent layers of the sheet-like formed body included in the target base sheet 2 is reached. . In this embodiment, the rolled laminated sheets (the first rolled laminated sheets, the second rolled laminated sheets, etc.) having the same number of laminated sheet-like formed bodies are rolled and rolled. In another embodiment, in the step (1 '), rolled laminated sheets having different numbers of laminated sheet-like formed bodies are overlapped and rolled. In still another embodiment, in step (1 '), the sheet-like formed body is overlaid and rolled on the rolled laminated sheet.

  When performing the step (1 '), it is preferable to change the rolling direction. At this time, it is preferable that the rolling direction of a process (1) and the rolling direction of a process (1 ') are orthogonal. Further, when the step (1 ') is repeated, it is preferable to change the rolling direction (particularly 90 °). By rolling while changing the direction in this way, the PTFE network extends vertically and horizontally, and the sheet strength can be further improved and the heat conductive filler can be more firmly fixed to the fluororesin matrix.

  When the number of constituent layers of the final rolled laminated sheet to be the base sheet 2 is represented by the number of layers of the sheet-like formed body included in the rolled laminated sheet, the number of constituent layers may be, for example, 2 to 5000 layers. it can. In order to improve the sheet strength, the number of constituent layers is preferably 200 or more. On the other hand, the number of constituent layers is preferably 1500 or less for thinning (for example, a sheet having a thickness of 1 mm or less).

  As described above, the base sheet 2 having a thickness of preferably about 0.05 mm to 3 mm is finally obtained.

  Step (2) can be performed according to a known method depending on the molding aid to be used. For example, a sheet obtained by rolling may be heated to remove the molding aid by drying. Thereby, a porous base material is obtained.

  For the step (3), a known coating method can be used, and for example, pattern coating or printing technology can be used. When the pressure-sensitive adhesive material is a solid material such as a hot-melt adhesive, the pressure-sensitive adhesive material is liquefied by heating to a temperature equal to or higher than its melting temperature, and then the step (3) is performed. The viscosity of the applied adhesive material is preferably 1 to 100,000 mPa · s. The "viscosity of the applied adhesive material" refers to the viscosity when the adhesive material is a non-crosslinked adhesive, and when the adhesive material is a crosslinked adhesive, This refers to the viscosity before cross-linking. When the adhesive material is a thermosetting adhesive, it indicates the viscosity before curing. When the adhesive material is a hot-melt adhesive, the viscosity under heat-melting is used. Point to. In addition, these viscosities are viscosities at a temperature at which the application operation to the base sheet 2 is performed. It is preferable to dry the adhesive material applied to the base material sheet 2.

  Between the process (2) and the process (3), you may further implement the process (4) of pressure-molding the base material sheet 2 which is a porous base material. The porosity of the base sheet 2 after carrying out the step (2) is usually about 50 to 80%, but by carrying out the step (4), the porosity of the base sheet 2 is 40% or less. In addition, the heat conductive fillers are more densely present, and the thermal resistance of the heat radiating member 1 can be further reduced.

  The pressure molding can be performed, for example, by pressing at a temperature of 320 to 400 ° C. and a pressure of 0.05 to 50 MPa for 1 to 15 minutes.

  Although the heat radiating member of this invention can be obtained as mentioned above, the manufacturing method of the heat radiating member of this invention is not restricted above.

  The heat dissipating member of the present invention can be adhered to the heating element by appropriately selecting an attachment method according to the type of the adhesive material. For example, when the adhesive material is an adhesive, the heat dissipating member of the present invention may be placed on the surface of the adherend and pressed. When the adhesive material is a thermosetting adhesive, the heat dissipating member of the present invention may be disposed on the surface of the adherend and heated and pressed at a temperature equal to or higher than the thermosetting temperature of the adhesive. When the adhesive material is a hot-melt adhesive, the heat dissipating member of the present invention may be disposed on the surface of the adherend, heated and pressed at a temperature equal to or higher than the melting temperature of the adhesive, and cooled.

  As described above, the heat dissipating member 1 can be easily adhered to the adherend with a good adhesive force. Moreover, the heat radiating member of this invention has favorable thermal conductivity. And since the heat radiating member of this invention uses the fluororesin with high oil resistance, it is suitable for the use in an oil environment. Moreover, since a fluororesin shows comparatively high rigidity (Young's modulus), a gap is easily formed between the base sheet 2 and the heating element. When a fluid such as oil flows through the gap, the heat dissipation characteristics of the heat dissipation member 1 can be improved. Therefore, it is most suitable for a heat radiating member for a motor for a vehicle (eg, hybrid car, electric car, etc.), and by using the heat radiating member, the vehicle motor can be cooled with high efficiency over a long period of time. When used as a heat dissipation member for a vehicle motor, the air layer in the vehicle motor may be replaced with the heat dissipation member of the present invention. For example, when there is an air layer between the stator and the case, between the stator and the coil, between the case and the coil, between the stator and the stator, etc., the heat dissipating member of the present invention may be disposed between them. The usage pattern in the vehicle motor is not limited to this. The heat dissipating member of the present invention can of course be used for other than motors for vehicles (eg, generators, electronic devices, etc.).

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these Examples. First, the evaluation method performed in this example will be described.

<Thermal resistance>
The measurement of thermal resistance was performed using the thermal characteristic evaluation apparatus 10 shown in FIGS. 3A and 3B. The thermal characteristic evaluation apparatus 10 has a heating element (heater block) 11 in the upper part and a radiator (cooling base plate configured to circulate cooling water) 12 in the lower part. The radiator 12 has a rod 13 made of aluminum (A5052, thermal conductivity: 140 W / m · K) formed so as to be a cube having one side of 20 mm. A pair of pressure adjusting screws 14 penetrating the heat generating body 11 and the heat radiating body 12 are provided on the side portions of the pair of rods 13. A load cell 15 is provided between the pressure adjusting screw 14 and the heating element 11, whereby the pressure when the pressure adjusting screw 14 is tightened is measured. Three probes 16 (diameter 1 mm) of a contact displacement meter 17 are installed inside the rod 13 on the side of the radiator 12. When the sample (heat radiating member) is not disposed between the rods 13, the upper end of the probe 16 is in contact with the lower surface of the rod 13 on the upper side (heating element 11 side). The interval (sample thickness) can be measured. A temperature sensor 18 of a thermometer 19 is attached to the back side of the heating element 11 and the upper and lower rods 13. Specifically, temperature sensors 18 are attached to one place of the heating element 11 and five places at equal intervals in the vertical direction of each rod 13.

In the measurement, first, the heat radiating member 1 (20 mm × 20 mm) of each example and comparative example was sandwiched between the pair of rods 13 from above and below. The pressure adjusting screw 14 was tightened to apply pressure to the heat dissipating member 20 to set the temperature of the heating element 11 to 150 ° C. and to circulate 20 ° C. cooling water through the heat dissipating body 12. After the temperature of the heating element 11 and the upper and lower rods 13 is stabilized, the temperature of the upper and lower rods 13 is measured by each temperature sensor 18, and the thermal conductivity (W / m · K) and temperature gradient of the upper and lower rods 13 are measured. The heat flux passing through the heat radiating member 1 was calculated, and the temperature at the interface between the upper and lower rods 13 and the heat radiating member 20 was calculated. And using these, the thermal resistance (cm < ² > * K / W) in the said pressure was computed using the thermal conductivity equation (Fourier's law). In addition, the thermal resistance was calculated | required about the case where the pressure of 200 N was applied to the heat radiating member 20. FIG.
Q = −λgradT
R = L / λ
Q: Thermal flow rate per unit area gradT: Temperature gradient L: Sample (heat radiating member) thickness λ: Thermal conductivity R: Thermal resistance

<Peeling force>
The heat radiating member was cut into a size of 10 mm width and 40 mm length. A 180 mm peel test (peeling speed: 300 mm / min) is performed in an atmosphere of 23 ° C. by pressing a 2 kg heavy rubber roller on a 2 mm thick aluminum plate once in a reciprocating manner to determine the peeling force. It was.

<Example 1>
Boron nitride powder (manufactured by Denki Kagaku Kogyo Co., Ltd., product number “SGPS”) and PTFE powder (manufactured by Daikin Kogyo Co., Ltd., product number “F104U”) were mixed at a mass ratio of 80:20. A paste-like mixture was obtained by further adding 60 parts by mass of decane to 100 parts by mass of the mixture and kneading.

  By rolling the paste-like mixture thus obtained with a rolling roll, two sheet-like molded bodies having a thickness of 3 mm were formed. Next, a first laminated sheet having a number of laminations of 2 was formed by rolling the two sheet-like molded bodies on top of each other. Next, the 1st lamination sheet was cut | disconnected and divided into two, they were piled up and rolled, and the 2nd lamination sheet whose number of lamination | stacking was 4 was formed. A series of these steps of cutting, overlapping and rolling was repeated 5 times while changing the rolling direction by 90 °. The laminated sheet was rolled a plurality of times to obtain a rolled laminated sheet having a thickness of about 0.6 mm.

  Next, the obtained rolled laminated sheet was heated at 150 ° C. for 20 minutes to remove the molding aid. Subsequently, it pressed at 380 degreeC and 10 Mpa for 5 minutes, and obtained the base material sheet about 0.2 mm in thickness.

  Next, in a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 95 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid, 150 parts by weight of ethyl acetate and 2,2′-azobisisobutyro Nitrile (AIBN) 0.1 part by mass was added and a polymerization reaction (solution polymerization) was performed at 60 ° C. for 8 hours to obtain an acrylic polymer solution.

  20 parts by mass of rosin phenolic tackifier resin (manufactured by Sumitomo Bakelite, “Sumilite Resin PR12603”), 100 parts by mass of solid content of the obtained acrylic polymer solution, and an oil-soluble isocyanate-based crosslinking agent solution as an external crosslinking agent (Nippon Polyurethane Industry Co., Ltd., “Coronate L”, solid content concentration: 75% by mass) Add 1.33 parts by weight (1 part by weight in terms of solids) and dilute with 2280 parts by mass of ethyl acetate. An adhesive material solution having a content of 5% by mass was obtained.

The adhesive material solution was applied in the form of dots to one main surface of the base sheet obtained as described above using a dispenser (manufactured by Musashi Engineering Co., Ltd., “SM300DS-S, MPP-1”). A plurality of adhesive portions were formed. The formation pattern of the plurality of adhesive portions was as follows.
Shape of each dot: Distance between adjacent dots having a diameter of 2.2 mm: 5 mm
Dot placement: Placed on grid points of square grid

  The base material sheet coated with the adhesive material was heated in a drying oven at 130 ° C. for 3 minutes to obtain a heat radiating member according to Example 1. In Example 1, the ratio (coverage) between the area of one main surface of the base sheet and the area where the plurality of adhesive portions cover the main surface was 15.2%.

<Example 2 and Example 3>
Except having made the formation pattern of the some adhesion part into as Table 1, it carried out similarly to Example 1, and obtained the heat radiating member which concerns on Example 2 and Example 3. FIG.

<Example 4>
A heat radiating member of Example 3 was obtained in the same manner as in Example 1 except that the formation pattern of the adhesive portion was a line width of 1 mm and a line interval of 4.5 mm and was formed in a straight line extending in the same direction.

<Example 5>
A heat radiating member of Example 5 was obtained in the same manner as in Example 4 except that the formation pattern of the adhesive portion was as shown in Table 2.

<Comparative Example 1 and Comparative Example 2>
Except having made the formation pattern of the some adhesion part as Table 1, it carried out similarly to Example 1, and obtained the heat radiating member which concerns on the comparative example 1 and the comparative example 2. FIG.

<Comparative Example 3>
A heat radiating member according to Comparative Example 3 was obtained in the same manner as in Example 1 except that the adhesive portion was applied to the entire surface of one main surface of the base sheet.

<Comparative Example 4>
A heat radiating member of Comparative Example 4 was obtained in the same manner as in Example 4 except that the formation pattern of the adhesive portion was as shown in Table 2.

  About each Example and each comparative example, thermal resistance and peeling force were measured by said method. The results are shown in Table 1 and Table 2, respectively. Moreover, in Examples 1-3 and Comparative Examples 1-3, the graph which showed the relationship between a coverage and thermal resistance is shown in FIG.

  As shown in Table 1, the heat resistance of the heat dissipation members of Examples 1 to 3 is smaller than the heat resistance of Comparative Examples 1 to 3, and it is suggested that the heat dissipation members of Examples 1 to 3 exhibit good heat dissipation characteristics. It was done. Moreover, as shown in FIG. 4, it was shown that the thermal resistance of the heat radiating member is minimized when the coverage is around 30%.

Moreover, as shown in Table 1 and Table 2, it was suggested that when the distance between adjacent adhesive portions is in the range of 3 to 9 mm, the heat dissipation member exhibits a small thermal resistance.

  The heat dissipating member of the present invention is suitable for use in an oil environment and is useful as a heat dissipating member for a vehicle motor.

Claims (11)

A base material sheet based on a porous base material containing a fluororesin and a heat conductive filler;
A plurality of adhesive portions disposed away from each other on one main surface of the base sheet,
The fluororesin comprises polytetrafluoroethylene,
The area where the plurality of adhesive portions cover one main surface of the base sheet is 10% to 85% of the area of one main surface of the base sheet,
The heat radiating member in which the plurality of adhesive portions are arranged so that a continuous path from one end to the other end of the base sheet is formed on one main surface of the base sheet.   The heat radiating member of Claim 1 whose Young's modulus of the said base material sheet is 1 Mpa or more.   The heat radiating member of Claim 1 or 2 whose distance of the said adjacent adhesion parts is 3-9 mm.   The heat radiating member according to claim 1, wherein the plurality of adhesive portions are arranged in a dot shape.   The heat radiating member according to claim 1, wherein the plurality of adhesive portions are arranged at positions corresponding to lattice points of a square lattice.   The heat dissipation member according to claim 4 or 5, wherein the plurality of adhesive portions are circular.   The heat radiating member according to claim 1, wherein the plurality of adhesive portions are arranged in a straight line extending in the same direction.   The heat dissipation member according to any one of claims 1 to 7, wherein the fluororesin further includes at least one selected from the group consisting of a perfluoroalkoxy fluororesin and a tetrafluoroethylene-hexafluoropropylene copolymer. .   The heat radiating member according to any one of claims 1 to 8, wherein the thermally conductive filler is at least one insulating filler selected from the group consisting of boron nitride, aluminum nitride, alumina, silicon nitride, and magnesium oxide. .   The heat radiating member according to claim 1, wherein the heat conductive filler is at least one conductive filler selected from the group consisting of graphite, carbon black, carbon fiber, metal fiber, and metal particles. . A step (1) of obtaining a rolled laminated sheet by laminating and rolling a plurality of sheet-like molded bodies containing a polytetrafluoroethylene-containing fluororesin, a thermally conductive filler, and a molding aid;
A step (2) of obtaining the base material sheet by removing the molding aid from the obtained rolled laminated sheet, and an adhesive material is applied to one main surface of the obtained base material sheet to form a plurality of adhesive portions The manufacturing method of a heat radiating member including a process (3).

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