JP2019041069A - Thermally conductive molded article - Google Patents

Abstract

To provide a thermally conductive molded article having excellent thermal conductivity in both a height direction and a direction intersecting the height direction, using an expanded graphite sheet having high thermal conductivity in a main surface direction as compared to the thermal conductivity in the thickness direction.SOLUTION: A plurality of sheet-like expanded graphite sheets 10 having thermal conductivity higher in main plane directions x, y as compared with thermal conductivity in a thickness direction z is laminated in such a manner that main planes 10a overlaps each other, then the laminated graphite sheets 10 is compression-molded, accordingly a heat dissipating molded article 1 having a predetermined height is configured in which a compression direction is a height direction H.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat conductive molded body composed of a plurality of expanded graphite sheets.

Conventionally, for example, a heat conductive molded body with high heat dissipation is used as a heat radiator for a cooling unit or the like in a mobile device or an inverter control component.
On the other hand, expanded graphite having excellent thermal conductivity is also used as a material for a heat-dissipating sheet for diffusing heat generated from electronic components, for example (see Patent Document 1).

  However, such a sheet-like expanded graphite has an anisotropy in which the thermal conductivity in the thickness direction is only about 1/25 as compared with the thermal conductivity in the main surface direction. When the heat conductive molded body having the expanded graphite sheet is laminated in the thickness direction, the heat conductivity in the direction intersecting the height direction can be secured, but the height direction is the thickness direction of the sheet-like expanded graphite. Therefore, the heat conductivity in the height direction cannot be ensured, and the requirements for the heat conductive molded body cannot be satisfied.

  On the other hand, when a band-shaped expanded graphite sheet is wound in a spiral shape to form a heat conductive molded body having a predetermined height, the main surface of the expanded graphite sheet constituting the heat conductive molded body faces in the height direction. Therefore, although the heat conductivity in the height direction can be ensured, the radial direction intersecting the height direction becomes the thickness direction of the sheet-like expanded graphite. Could not satisfy the request.

JP 2005-229100 A

  Therefore, in the present invention, an expanded graphite sheet having higher heat conductivity in the principal surface direction than heat conductivity in the thickness direction is used, and has excellent heat conductivity in both the height direction and the direction intersecting the height direction. It aims at providing a heat conductive molding.

The heat conductive molded body is formed by laminating a plurality of expanded graphite sheets in the form of a sheet whose heat conductivity in the main surface direction is higher than that in the thickness direction so that the main surfaces overlap, and on the main surface. It is compression-molded in the intersecting direction and has a predetermined height with the compression direction as the height direction.
With this heat conductive molded body, excellent heat conductivity can be exhibited in both the height direction and the direction intersecting the height direction.

  More specifically, a plurality of expanded graphite sheets in the form of a sheet having higher heat conductivity in the main surface direction than in the thickness direction are laminated so that the main surfaces overlap, and in a direction intersecting the main surface. The main surface of the expanded graphite sheet intersects the height direction and the height direction of the heat conductive molded body in order to form a heat conductive molded body having a predetermined height in which the compression direction is the height direction by compression molding. Therefore, excellent thermal conductivity can be exhibited in both the height direction and the direction intersecting the height direction.

In addition, if the lamination direction of an expanded graphite sheet is not a height direction, a heat conductive molded object can be made into various shapes which have predetermined | prescribed height.
In addition, the heat conductive molded body is a mold that can use heat conductivity according to the application, such as a heat radiating body for transferring heat to dissipate heat, or a heat absorbing body or heat transfer body for positively transferring heat. It may be a body.

As an aspect of the heat conductive molded body, the shape having a predetermined height and intersecting the height direction may be an annular shape, and the expanded graphite sheet may be arranged in the radial direction of the annular shape.
The ring may be an annular ring, a square ring, or an appropriate ring, and the radial direction is a direction connecting the inner side and the outer side of the ring, for example, in the radial direction.

By this heat conductive molded body, in a circular heat conductive molded body having a predetermined height, excellent heat conductivity can be exhibited in both the height direction and the radial direction intersecting the height direction.
Specifically, because the expanded graphite sheet has a predetermined height and is arranged toward the radial direction in the ring intersecting the height direction, that is, the stacking direction of the expanded graphite sheet is a direction along the ring, Since the main surface is along the radial direction and the height direction, excellent thermal conductivity can be exhibited in both the height direction and the radial direction.

Moreover, as an aspect of this heat conductive molded body, the expanded graphite sheet may be curved with respect to the height direction.
By this heat conductive molded body, the bonding strength in the height direction between the expanded graphite sheets to be laminated is improved, and the durability can be increased.

Moreover, as an aspect of this heat conductive molded body, the expanded graphite sheet may be curved with respect to the radial direction.
With this heat conductive molded body, the bond strength in the radial direction between the expanded graphite sheets to be laminated is improved, and the durability can be increased.

Moreover, as an aspect of this heat conductive molded object, the said expanded graphite sheet may face in the direction which cross | intersects with respect to the said radial direction.
The thermal conductivity in the radial direction can be adjusted by this thermally conductive molded body.

  More specifically, the expanded graphite sheet is formed in a longer length in the radial direction than in the radial direction, that is, in the radial direction, by being directed in a direction intersecting the radial direction. can do. That is, the radial length of the expanded graphite sheet can be adjusted according to the direction crossing the radial direction, and the thermal conductivity in the radial direction of the thermally conductive molded body can be adjusted by the length of the expanded graphite sheet.

  According to the present invention, it is possible to provide a heat conductive molded body having excellent heat conductivity in both the height direction and the direction intersecting the height direction.

Explanatory drawing about an expanded graphite sheet and a heat dissipation molded object. The top view and front view of a heat dissipation molded object. Explanatory drawing about the manufacturing method of a thermal radiation molded object. Explanatory drawing about the manufacturing method of a thermal radiation molded object. Explanatory drawing about the manufacturing method of a thermal radiation molded object. The front view of a heat dissipation molded object. The top view of a heat dissipation molded object.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory view of the heat dissipation molded body 1, FIG. 2 is a plan view and a front view of the heat dissipation molded body 1, and FIGS. 3 to 5 are explanatory views of a manufacturing method of the heat dissipation molded body 1, FIG. 6 shows a front view of the heat dissipation molded body 1 in which the compressed shape of the expanded graphite sheet 10 in the height direction H is different, and FIG. 7 shows the heat dissipation molded body 1 in which the expanded graphite sheet 10 is in the direction intersecting with the radial direction R. FIG.

  Specifically, FIG. 1A shows a perspective view of an expanded graphite sheet 10 constituting the heat dissipation molded body 1, and FIG. 1B shows a perspective view of the heat dissipation molded body 1. FIG. 3A shows a perspective view of a state in which a plurality of expanded graphite sheets 10 constituting the heat dissipation molded body 1 are arranged, and FIG. 3B shows a perspective view of a compression lower mold 110 constituting the heat dissipation molded body 1. ing.

  4A shows a perspective view of a state in which a plurality of expanded graphite sheets 10 are arranged on the compression lower mold 110, FIG. 4B shows a sectional view of the same state, and FIG. The perspective view of the state which compressed the expanded graphite sheet 10 with the upper mold | type 120 is shown, FIG.5 (b) has shown sectional drawing of the state. 4A and 5B, the front half of the compression upper mold 120 is not shown and only the back half is shown for easy understanding.

  6A shows a front view of the heat dissipation molded body 1 in which the expanded graphite sheet 10 bends in the height direction H, and FIG. 6B shows the expanded graphite sheet 10 intersecting in the height direction H. The front view of the heat-radiation molded object 1 which becomes direction is shown.

  1 and FIGS. 3 to 7, for convenience of explanation, the boundary of the expanded graphite sheet 10 constituting the heat-dissipating molded body 1 is clearly illustrated, and the orientation of the expanded graphite sheet 10 is described. Actually, since the expanded graphite sheet 10 is integrated with the heat dissipation molded body 1 by compression molding, the boundary of the expanded graphite sheet 10 may be unclear.

The heat dissipation molded body 1 is a heat transfer heat dissipator that is used, for example, in a cooling part of an injector device and has high heat dissipation in the height direction H and the radial direction R, and is formed in an annular shape in plan view having a predetermined height. ing.
In the present embodiment, as shown in FIG. 1B, FIG. 2B, etc., the direction along the height of the heat dissipation molded body 1 is defined as the height direction H, and an annular shape in plan view of the heat dissipation molded body 1 The direction from the center to the outside is the radial direction R. Moreover, in this embodiment, the heat-radiation molded object 1 is formed in the annular | circular shape whose height direction H is 20 mm, the internal diameter of radial direction R is 24 mm, and an outer diameter is 37 mm. As for the radial direction R, in the drawings, only four directions are illustrated as an example at intervals of approximately 90 degrees, but any direction that extends radially outward from the center of the annular ring in plan view. It may be.

  The heat-radiation molded body 1 formed in this way is obtained by arranging the expanded graphite sheet 10 shown in FIG. 1A in the circumferential direction with respect to the center of the heat-radiation molded body 1 in plan view, as shown in FIG. As shown in FIG. 2 (b), the expanded graphite sheet 10 is compressed and integrated so as to curve in a substantially S shape with respect to the height direction H, as shown in FIG.

  The expanded graphite sheet 10 is a rectangular sheet having an appropriate thickness t with respect to the main surface 10a and having a predetermined length in main surface directions x and y to be described later. In this embodiment, as shown in FIG. 1A, the direction along the thickness of the expanded graphite sheet 10 is defined as the thickness direction z, and the two directions perpendicular to the thickness direction z and perpendicular to each other are the principal surface directions. x, y. The thickness t can be arbitrarily set regardless of the lengths of the principal surface directions x and y.

Such an expanded graphite sheet 10 has an anisotropy in which the thermal conductivity in the thickness direction z is only about 1/25 compared to the thermal conductivity in the principal surface directions x and y.
In FIGS. 1 (a) and 3 (a), the expanded graphite sheet 10 is shown with a large thickness t for easy understanding, but in this embodiment, the expanded graphite sheet 10 has a thickness t of 0.75 mm. A sheet 10 is used. In the expanded graphite sheet 10 having such a thickness t, in a 21 ° C. environment, the thermal conductivity in the principal surface directions x and y is 138 W / m · K, whereas the thermal conductivity in the thickness direction z is 5 W / m · K, which is about 1/25.

  Next, heat dissipation in the height direction H and the radial direction R is configured using the expanded graphite sheet 10 having a lower thermal conductivity in the thickness direction z than the thermal conductivity in the principal surface directions x and y. The manufacturing method of the heat-radiation molded object 1 with high is demonstrated with FIG. 3 thru | or FIG.

  First, as shown in FIGS. 3 and 4, a plurality of expanded graphite sheets 10 are oriented so that the main surface 10a is oriented along the height direction H and the radial direction R, and the main surfaces 10a overlap each other. It arrange | positions along a visual periphery direction and sets to the compression space X of the compression lower mold | type 110 which compresses and molds the expanded graphite sheet 10. FIG. Here, in the present embodiment, the expanded graphite sheet 10 is set so that the x direction of the major surface directions x and y of the major surface 10a faces the height direction H and the y direction faces the radial direction R. .

Note that a compression device that compresses the expanded graphite sheet 10 to form the heat dissipation molded body 1 includes a compression lower mold 110 and a compression upper mold 120. As shown in FIG. 3B, the compression lower mold 110 includes a cylindrical recess 111 and a columnar portion 112 disposed in the center of the cylindrical recess 111 in a plan view, and a cylindrical compression space X is formed. Yes.
The compression space X is formed in the same annular shape as the heat radiation molded body 1 in plan view, and is formed deeper than the height direction H of the heat radiation molded body 1.

  The compression upper mold 120 is integrally formed of an upper mold main body 121 and a cylindrical convex portion 122 that protrudes downward from the bottom surface of the upper mold main body 121. The cylindrical convex portion 122 is formed with an outer shape that can be fitted into the cylindrical concave portion 111 of the lower compression mold 110 and an inner shape that can be fitted with the column portion 112.

  The expanded graphite sheet 10 disposed in the compression space X has a length in the y direction slightly shorter than the length in the radial direction R of the compression space X, and the length in the x direction is the height direction of the heat dissipation molded body 1. It is formed longer than H. In this embodiment, 120 expanded graphite sheets 10 are arranged in the circumferential direction and set in the compression space X as described above, but the number is reduced for convenience. Moreover, the number of sheets used of the expanded graphite sheet 10 can be arbitrarily changed according to the purpose, application, use conditions, etc. of the heat dissipation molded body 1.

  In this way, the expanded graphite sheet 10 whose length in the y direction is slightly shorter than the length in the radial direction R of the compression space X and whose length in the x direction is longer than the height direction H of the heat dissipation molded body 1 is compressed. After the arrangement in the space X, the cylindrical convex portion 122 of the compression upper mold 120 is inserted from above the compression lower mold 110 into the upper part of the expanded graphite sheet 10 in the compression space X, and as shown in FIG. The mold 110 is press-fitted until the upper surface 110a of the mold 110 and the bottom surface of the upper mold body 121 of the compression upper mold 120 face each other.

  As described above, the expanded graphite sheet 10 disposed in the compression space X is press-fitted until the upper surface 110a of the compression lower mold 110 and the bottom surface of the upper mold body 121 of the compression upper mold 120 face each other, as described above. Are compressed and integrated so as to be bent in a substantially S shape with respect to the height direction H. Thereby, the thermal radiation molded object 1 can be comprised from the some expanded graphite sheet 10. FIG.

  Depending on the arrangement of the expanded graphite sheet 10 in the compression space X and the amount of compression in the height direction H with respect to the length in the x direction, the expanded graphite sheet 10 does not curve in a substantially S shape with respect to the height direction H. The expanded graphite sheet 10 may be linear in the height direction H. For example, the expanded graphite sheet 10 is compressed so as to be bent with respect to the height direction H as shown in FIG. In some cases. Furthermore, as shown in FIG. 6B, the expanded graphite sheet 10 may face in a direction that intersects the height direction H.

  Thus, the heat dissipation molded body 1 having a predetermined height includes a plurality of expanded graphite sheets 10 having a sheet shape having a higher thermal conductivity in the principal surface directions x and y than the thermal conductivity in the thickness direction z. The main surface 10a is laminated so that it overlaps, and it is compression molded in the main surface directions x and y, and the compression direction is the height direction H, so it exhibits excellent thermal conductivity in both the height direction H and the radial direction R. can do.

  More specifically, a plurality of expanded graphite sheets 10 in the form of a sheet having higher thermal conductivity in the main surface directions x and y than the thermal conductivity in the thickness direction z are stacked so that the main surfaces 10a overlap, and the main surface The main surface 10a of the expanded graphite sheet 10 is formed in the height direction of the heat dissipation molded body 1 in order to form the heat dissipation molded body 1 having a predetermined height in which the compression direction is the height direction H by compression molding in the directions x and y. Excellent thermal conductivity can be exhibited in both the height direction H and the radial direction R in the H direction and the radial direction R.

  Further, the heat dissipation molded body 1 has a predetermined height because the shape in plan view intersecting the height direction H is an annular shape, and the expanded graphite sheet 10 is arranged in the annular radial direction R. In the annular heat dissipation molded body 1, excellent thermal conductivity can be exhibited in both the height direction H and the radial direction R intersecting the height direction H.

  Specifically, since the expanded graphite sheet 10 has a predetermined height and is arranged in the radial direction R in the annular shape in plan view, that is, the stacking direction of the expanded graphite sheet 10 is a direction along the annular shape. Since the surface 10a is along the radial direction R and the height direction H, excellent thermal conductivity can be exhibited in both the height direction H and the radial direction R.

  In addition, since the thickness direction z of the expanded graphite sheet 10 faces the circumferential direction of the annular shape in a plan view, the annular heat dissipation molded body 1 has a low thermal conductivity in the circumferential direction, but the height direction H and the radial direction R. Because of its excellent thermal conductivity, it exhibits excellent thermal conductivity for the top and bottom surfaces of the heat dissipation molded body 1 as well as the inner peripheral surface and the outer peripheral surface. can do.

  Further, when the expanded graphite sheet 10 is curved in a substantially S shape with respect to the height direction H, or when the expanded graphite sheet 10 is bent with respect to the height direction H as shown in FIG. The bonding strength in the height direction H between the expanded graphite sheets 10 to be laminated is improved, the density is improved, and the durability of the heat dissipation molded body 1 can be improved.

Note that, as shown in FIG. 7, the expanded graphite sheet 10 of the heat-dissipation molded body 1 may be curved in the radial direction R while facing the direction intersecting the radial direction R.
Also in this case, the bonding strength in the radial direction R between the expanded graphite sheets 10 to be laminated can be improved, and the durability of the heat dissipation molded body 1 can be improved.

In particular, by directing the expanded graphite sheet 10 in a direction crossing the radial direction R, the thermal conductivity in the radial direction R of the heat dissipation molded body 1 can be adjusted.
More specifically, the expanded graphite sheet 10 is arranged in the radial direction from the center of the annular shape in plan view, as shown in FIG. Compared to the case, the expanded graphite sheet 10 having a long length in the y direction can be used even in the same annular shape in plan view.

  Here, since the expanded graphite sheet 10 constituting the heat dissipation molded body 1 has low thermal conductivity in the thickness direction z as described above, heat conduction is performed between the expanded graphite sheets 10 that are laminated so that the principal surfaces 10a face each other. However, since heat conduction is performed in the principal surface directions x and y of the expanded graphite sheet 10, the thermal conductivity in the radial direction R of the heat dissipation molded body 1 contributes to the length of the expanded graphite sheet 10 in the y direction. .

  As described above, by directing the expanded graphite sheet 10 in a direction crossing the radial direction R, or by bending the expanded graphite sheet 10 with respect to the radial direction R, the length of the expanded graphite sheet 10 in the y direction can be increased. The thermal conductivity in the radial direction R of the heat dissipation molded body 1 can be adjusted by adjusting the length of the expanded graphite sheet 10 in the y direction.

  Of course, as shown in FIG. 6, the thermal conductivity in the height direction H of the heat-radiation molded body 1 can also be adjusted by curving the expanded graphite sheet 10 with respect to the height direction H or by turning it in the intersecting direction. However, the amount of adjustment for adjusting the length of the expanded graphite sheet 10 in the x direction is smaller than in the case where the expanded graphite sheet 10 is directed in the direction intersecting the radial direction R.

As described above, in the correspondence between the configuration of the present invention and the above-described embodiment, the thickness direction of the present embodiment corresponds to the thickness direction z,
Similarly,
The surface direction corresponds to the principal surface direction x, y,
The expanded graphite sheet corresponds to the expanded graphite sheet 10,
The direction intersecting the surface and the radial direction correspond to the radial direction R,
The height direction corresponds to the height direction H,
Although a heat conductive molded object respond | corresponds to the thermal radiation molded object 1, it is not limited to the said embodiment.

  In the above description, the heat dissipating molded body 1 having an annular shape in plan view is configured, but may be a square ring or an appropriate ring. Various shapes having a height can be employed.

  Moreover, although the heat-radiation molded object 1 was a heat radiating body for transferring heat and radiating heat, it uses heat conductivity according to the application such as a heat absorbing body or a heat transfer body for positively transferring heat. You may use as a possible molded object.

DESCRIPTION OF SYMBOLS 1 ... Heat dissipation molded object 10 ... Expanded graphite sheet H ... Height direction R ... Radial direction x, y ... Main surface direction z ... Thickness direction

Claims (5)

A plurality of expanded graphite sheets that are in the form of a sheet having higher thermal conductivity in the principal surface direction than the thermal conductivity in the thickness direction are laminated so that the principal surfaces overlap, and are compressed in the direction intersecting the principal surface. A heat conductive molded body having a predetermined height in which the compression direction is the height direction. A shape having a predetermined height and intersecting the height direction is annular,
The heat conductive molded object according to claim 1, wherein the expanded graphite sheet is arranged in a radial direction in the annular shape. The heat conductive molded body according to claim 2, wherein the expanded graphite sheet is curved with respect to the height direction. The heat conductive molded body according to claim 2 or 3, wherein the expanded graphite sheet is curved with respect to the radial direction. The thermally conductive molded article according to claim 2 or 3, wherein the expanded graphite sheet is oriented in a direction intersecting the radial direction.

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