Anisotropic thermal conductive resin member and manufacturing method thereof

Abstract

An aspect of the present invention is an anisotropic thermal conductive resin member including a plurality of bundled thermoplastic resin stretch fibers.

Claims

1. A method of manufacturing an anisotropic thermal conductive resin member, comprising: a step of producing stretch fibers by stretching a thermoplastic resin, wherein the thermoplastic resin consists of at least one selected from the group consisting of an acrylic polymer, a methacrylic polymer, polyethylene terephthalate, polyarylate, polysulfone, and polyether ether ketone; and a step of bundling the plurality of stretch fibers by at least one binder selected from the group consisting of polyurethane, an acrylic polymer, and an epoxy resin wherein the anisotropic thermal conductive resin member consists of the stretch fibers and the at least one binder.

2. The method according to claim 1, wherein a diameter of each of the stretch fibers is 200 μm or less.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1(a) is a perspective view showing a resin member according to one embodiment, and FIG. 1(b) is a schematic view showing movement of phonons in a stretch fiber.

(2) FIG. 2 is a schematic view showing a stretch fiber producing step according to one embodiment.

DESCRIPTION OF EMBODIMENTS

(3) Embodiments of the present invention will be appropriately described below in detail with reference to the drawings.

(4) FIG. 1(a) is a perspective view showing a resin member according to one embodiment. As shown in FIG. 1(a), a resin member 1 includes a plurality of bundled stretch fibers (also called fiber strands) 2, and is formed into a fiber form.

(5) For example, the plurality of stretch fibers 2 are aggregated (bundled) by a binder 3 that binds the stretch fibers 2 so that they extend in substantially the same direction. When viewed in a cross section, the plurality of stretch fibers 2 may be regularly arranged or irregularly arranged. For example, as shown in FIG. 1(a), the cross-sectional shape of the stretch fibers 2 may be a substantially perfect circle, or may be a regular shape such as an elliptical shape or a polygonal shape, or may be an irregular shape.

(6) The stretch fibers 2 are fibers obtained by stretching a thermoplastic resin. Examples of thermoplastic resins include an acrylic polymer, a methacrylic polymer, polyamide, polyethylene terephthalate, polyarylate, polysulfone, and polyether ether ketone.

(7) In consideration of both ease of phonon confinement and ease of phonon incidence, the diameter (maximum diameter) of the stretch fiber 2 is preferably 0.1 μm or more, more preferably 10 μm or more, and still more preferably 100 μm or more. In consideration of handling properties when bundling, the diameter (maximum diameter) of the stretch fiber 2 is preferably 1,000 μm or less, more preferably 500 μm or less, and still more preferably 200 μm or less.

(8) The binder 3 is not particularly limited, and may be made of, for example, polyurethane, an acrylic polymer, an epoxy resin or the like.

(9) FIG. 1(b) is a schematic view showing movement of phonons in the stretch fibers 2. In the resin member 1, since the stretch fibers 2 are fibers having high orientation, even if they are formed of a thermoplastic resin having low crystallinity, as shown in FIG. 1(b), phonons P are easily confined in the stretch fibers 2. Therefore, heat (phonons) is conducted with anisotropy (directivity) in the extension direction of the stretch fibers 2. That is, the resin member 1 has anisotropic thermal conductivity in which phonons are unlikely to be conducted between the stretch fibers 2 and heat can be anisotropically conducted in one extension direction of the stretch fibers 2. In addition, in the resin member 1, when the plurality of stretch fibers 2 are bundled, the cross-sectional area of the heat conduction path (the stretch fibers 2) is larger, and thus heat can be conducted with high efficiency.

(10) Next, a method of manufacturing the resin member 1 will be described. This manufacturing method includes a step in which a thermoplastic resin is stretched to produce stretch fibers (stretch fiber producing step) and a step in which the plurality of stretch fibers are bundled (bundling step).

(11) FIG. 2 is a schematic view illustrating a stretch fiber producing step according to one embodiment. In the stretch fiber producing step, first, as shown in FIG. 2, a thermoplastic resin 4 is heated in a heating furnace 5 and stretched in a winding direction (pulling direction) by being wound (pulled) by a winding part 6. Specifically, first, for example, the thermoplastic resin 4 molded into a rod having a diameter of 5 to 50 mm is put into the heating furnace 5. The thermoplastic resin 4 is heated in the heating furnace 5 and stretched by being wound (pulled) by the winding part 6 installed at the tip of the heating furnace 5.

(12) The temperature of the heating furnace 5 is appropriately set according to the softening temperature of the thermoplastic resin 4, and in order to suitably impart orientation when the thermoplastic resin 4 is stretched, preferably, the temperature is equal to or higher than a thermal distortion temperature of the thermoplastic resin and lower than the melting point. The thermoplastic resin 4 is stretched, for example, under conditions in which the stretch ratio is 10 to 1,000.

(13) The stretch fibers 2 thus ejected from the heating furnace 5 in this manner are formed into a fine wire having a diameter smaller than the diameter of the thermoplastic resin 4 (the diameter of the rod) before they are put into the heating furnace 5. The stretch fibers 2 are wound around the winding part 6 along a roller 7 that is appropriately provided between the heating furnace 5 and the winding part 6.

(14) In the bundling step following the stretch fiber producing step, a plurality of stretch fibers 2 are prepared, and the plurality of stretch fibers 2 are bundled using the binder 3. The bundling method may be a known method. Thereby, the resin member 1 is obtained.

(15) In the method of manufacturing the resin member 1 described above, when the stretch fibers 2 having high orientation are produced by stretching, even if they are formed of a thermoplastic resin having low crystallinity, the stretch fibers 2 that easily confine phonons P in fibers are obtained. Therefore, in this manufacturing method, the resin member 1 that conducts heat with anisotropy (directivity) in the extension direction of the stretch fibers 2 is obtained. In addition, in the method of manufacturing the resin member 1, the cross-sectional area of the heat conduction path (the stretch fibers 2) is increased by bundling the plurality of stretch fibers 2, and thus the resin member 1 capable of conducting heat with high efficiency is obtained.