Heat-radiating composite film

Abstract

The present invention is a heat-radiating composite film having a heat-radiating layer and an adhesive layer, the heat-radiating composite film being characterized in that the thickness of the heat-radiating layer is 5 [mu] m or more and 200 [mu] m or less, one surface of the heat-radiating layer is a rough surface, and the rough surface has an emissivity of 0.80 or more and an expansion area ratio of 1.5 or more. And the adhesive layer is arranged on the surface, opposite to the rough surface, of the heat radiation layer. As a result, it is possible to provide a heat-radiating composite film capable of effectively reducing the temperature of a heat source.

Description

Technical Field

[0001] The present invention relates to a heat-radiating composite film. Background Art

[0002] Conventionally, in electronic devices and the like, a heatsink using a metal plate having a high thermal conductivity such as aluminum or copper has been used to suppress the temperature rise of a chip during operation. The heatsink conducts the heat generated by the chip and releases the heat from the surface using the temperature difference with the external air.

[0003] However, due to the miniaturization, thinning, and high performance of devices, the situation where a heatsink cannot be mounted is gradually increasing. For example, smartphones, digital video cameras, LED lighting, etc. require heat dissipation measures without using a heatsink due to size or weight problems.

[0004] In response to this, several heat dissipation countermeasure components using thermal radiation have been reported.

[0005] Patent Document 1 proposes a scheme in which a layer having a high emissivity is provided on one surface of a heat-conducting layer having good in-plane thermal conductivity, and a low thermal resistance adhesive layer is provided on the other surface, and then attached to a heat source. Thus, even in a gap where a heatsink cannot be installed, construction can be easily performed. However, in Patent Document 1, the emissivity of the heat-radiating layer is limited to 0.8 or more, but the maximum value of the emissivity is 1.0, and it is still insufficient as a heat dissipation countermeasure required in recent years.

[0006] Patent Document 2 proposes a scheme in which a ceramic material obtained by sintering cordierite powder is molded and used as a substitute for a heatsink or a substrate, whereby the heat from the heating element is dissipated as radiant heat. However, for this method, due to the high rigidity of the ceramic material, molding is difficult, and there is also a problem that it cannot be applied when the surface of the heat dissipation member is not flat.

[0007] In addition, a method has been proposed in which a substance obtained by diluting a curable resin composition containing particles having a high heat emissivity, called a heat-radiating paint, with an appropriate organic solvent is coated or sprayed on a heating element and dried and cured, so that a heat-radiating layer is directly laminated on the heating element to dissipate the heat from the heating element to the outside of the system (for example, Patent Documents 3 and 4). However, for coating or spraying on a heating element, the following situations can be cited, and it has the disadvantage of complicated processes: it is necessary to introduce equipment for coating or spraying; it is difficult to control the coating amount and spraying amount; a process for curing the paint is required, etc.

[0008] In addition, Patent Document 5 proposes a heat radiation sheet in which a heat radiation film is formed on one side of a metal thin plate, and an adhesive layer is bonded to the other side of the metal thin plate. However, according to the embodiment of Patent Document 5, the thickness of the adhesive layer is 180 μm, which is very thick and hinders the flow of heat.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-208458

[0012] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2006-298703.

[0013] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2004-43612

[0014] Patent Document 4: Japanese Unexamined Patent Application Publication No. 2013-144747

[0015] Patent Document 5: Japanese Unexamined Patent Application Publication No. 2004-200199 Summary of the Invention

[0016] (I) Technical Problem to be Solved

[0017] The present invention has been completed in view of the above circumstances, and an object thereof is to provide a heat-radiating composite film capable of effectively reducing the temperature of a heat source.

[0018] (II) Technical Solution

[0019] In order to solve the above technical problem, the present invention provides a heat-radiating composite film having a heat-radiating layer and an adhesive layer, and the heat-radiating composite film is characterized in that

[0020] the thickness of the heat-radiating layer is 5 μm or more and 200 μm or less, one surface of the heat-radiating layer is a rough surface, the emissivity of the rough surface is 0.80 or more, and the unfolded area ratio is 1.5 or more,

[0021] the adhesive layer is provided on the surface opposite to the rough surface of the heat-radiating layer.

[0022] As long as it is such a heat-radiating composite film, it can effectively reduce the temperature of the heat source and the internal temperature of the housing. In addition, the heat-radiating composite film of the present invention has an adhesive layer and is in the form of a film, so it can be easily applied to the heat source and the housing.

[0023] Preferably: the heat-radiating layer contains any one selected from the group consisting of polyester resin, fluororesin, acrylic resin, epoxy resin, urethane resin, and polyolefin resin.

[0024] As long as a heat-radiating composite film using a heat-radiating layer containing the above materials is used, sufficient flexibility can be exhibited.

[0025] Preferably, one or more base material layers are further provided between the heat-radiating layer and the adhesive layer, and the base material layer contains any one or more selected from the group consisting of polyester resins, fluororesins, acrylic resins, epoxy resins, polyurethane resins, polyolefin resins, silicone resins, and metal foils.

[0026] Such a base material layer can sufficiently ensure adhesion to the heat-radiating layer and improve the strength of the heat-radiating composite film.

[0027] At this time, more preferably, the total thickness of the heat-radiating layer and the base material layer is 30 μm or more and 200 μm or less, and the ratio of the thickness of the heat-radiating layer to the thickness of the base material layer is 0.02 or more and 39 or less.

[0028] As long as a heat-radiating composite film of a heat-radiating layer and a base material layer having the above relationship is used, a better balance between excellent heat radiation and high strength can be exhibited.

[0029] Preferably, the base material layer is a metal foil having a thermal conductivity in the plane direction of 200 W / mK or more.

[0030] As long as a heat-radiating composite film containing such a base material layer is used, heat can be conducted from a heat source to the heat-radiating layer with good efficiency.

[0031] Preferably, the thermal resistance of the adhesive layer is 1.2 cm 2 ·K / W or less.

[0032] As long as a heat-radiating composite film containing such an adhesive layer is used, heat can be conducted from a heat source to the heat-radiating layer with better efficiency.

[0033] The adhesive layer can contain a thermally conductive filler.

[0034] As long as a heat-radiating composite film containing such an adhesive layer is used, heat can be conducted from a heat source to the heat-radiating layer with better efficiency.

[0035] For example, the adhesive layer can be a cured product of a silicone composition, and the silicone composition takes the following components as essential components:

[0036] (a) A linear organopolysiloxane having alkenyl, which is 100 parts by mass;

[0037] (b) A thermally conductive filler, and 300 to 900 parts by mass thereof;

[0038] (c) An organohydrogenpolysiloxane in an amount such that the molar ratio of the hydrogen atoms directly bonded to silicon atoms in component (c) to the alkenyl groups in component (a) is 0.5 to 20; and

[0039] (d) A platinum group metal-based catalyst in an amount of 0.1 to 1,000 ppm of component (a) in terms of the mass of the platinum group metal element.

[0040] As long as it is a heat-radiating composite film containing such an adhesive layer, it has good adhesiveness and can conduct heat from a heat source to a heat-radiating layer with better efficiency.

[0041] At this time, it is preferable that the organosilicon composition further has: (e) an organosilicon resin having a branched structure in an amount of 50 to 300 parts by mass.

[0042] This component (e) can impart cohesive property to the adhesive in the adhesive layer.

[0043] (III) Beneficial effects

[0044] As described above, as long as it is the heat-radiating composite film of the present invention, it can effectively reduce the temperature of the heat source and the internal temperature of the housing. In addition, since the heat-radiating composite film of the present invention has an adhesive layer and is in the form of a film, it can be easily applied to the heat source and the housing. Brief description of the drawings

[0045] Figure 1 It is a schematic cross-sectional view showing an example of the heat-radiating composite film of the present invention.

[0046] Figure 2 It is a schematic cross-sectional view showing another example of the heat-radiating composite film of the present invention. Detailed description of the invention

[0047] As described above, there is a need to develop a heat-radiating composite film that can effectively reduce the temperature of a heat source.

[0048] The inventors of the present application repeatedly conducted in-depth studies on the above technical problems and found that the following heat-radiating composite film can effectively reduce the temperature of the heat source and the internal temperature of the housing, thus completing the present invention. In this heat-radiating composite film, the thickness of the heat-radiating layer is 5 μm or more and 200 μm or less, one surface of the heat-radiating layer is a rough surface, the emissivity of the rough surface is 0.80 or more, and the spread area ratio is 1.5 or more, and an adhesive layer is provided on the surface opposite to the rough surface of the heat-radiating layer.

[0049] That is, the present invention is a heat-radiating composite film having a heat-radiating layer and an adhesive layer, and the heat-radiating composite film is characterized in that

[0050] The thickness of the thermal radiation layer is 5 μm or more and 200 μm or less. One surface of the thermal radiation layer is a rough surface, and the emissivity of the rough surface is 0.80 or more and the unfolded area ratio is 1.5 or more.

[0051] The adhesive layer is provided on the surface opposite to the rough surface of the thermal radiation layer.

[0052] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0053] Figure 1 FIG. is a schematic cross-sectional view showing an example of the heat-radiating composite film of the present invention.

[0054] Figure 1 The heat-radiating composite film 10 has a thermal radiation layer 1 and an adhesive layer 2. One surface 11 of the thermal radiation layer 1 is a rough surface. In addition, the adhesive layer 2 is provided on the surface 12 opposite to the rough surface 11 of the thermal radiation layer 1.

[0055] As Figure 1 shown, the adhesive layer 2 can be directly provided on the surface 12 opposite to the rough surface 11 of the thermal radiation layer 1. Alternatively, as Figure 2 shown, a base material layer 3 may be provided on the opposite surface 12 of the thermal radiation layer 1, and the adhesive layer 2 may be provided on the base material layer 3. The base material layer 3 may be one layer or more than one layer. That is, the heat-radiating composite film 10 of the present invention may further have one or more base material layers 3 between the thermal radiation layer 1 and the adhesive layer 2.

[0056] Hereinafter, each component of the heat-radiating composite film of the present invention will be described in more detail.

[0057] [Thermal radiation layer]

[0058] In the heat-radiating composite film 10 of the present invention, the thermal radiation layer 1 is characterized in that the thickness is 5 μm or more and 200 μm or less, preferably 10 μm or more and 100 μm or less. When it is less than 5 μm, it is difficult to form a rough surface with an unfolded area ratio of 1.5 or more on one surface 11. If it exceeds 200 μm, the heat conduction efficiency inside the heat-radiating composite film 10 will deteriorate.

[0059] In addition, the emissivity of the surface of the thermal radiation layer 1 is characterized in that it is 0.80 or more, preferably 0.83 to 0.99. When it is less than 0.80, a sufficient heat dissipation effect cannot be obtained. In addition, in the present invention, the emissivity is a value measured using a thermal radiation meter (TSS-5X-2 manufactured by JAPANSENSOR CORPORATION).

[0060] Further, one surface 11 of the heat radiation layer 1 is characterized by being a rough surface with a spread area ratio of 1.5 or more, more preferably 1.7 or more. When the spread area ratio is less than 1.5, sufficient effects cannot be obtained. The upper limit of the spread area ratio is not particularly limited and can be set to 4.0, for example. In addition, in the present invention, the spread area ratio is set as the ratio of the surface area / area, which is a value calculated from the measurement area of the film surface measured by a digital microscope (VHX-6000 manufactured by KEYENCE Corp.) and the surface area of the measurement area.

[0061] The heat-radiating composite film 10 of the present invention, which includes the above heat radiation layer 1 and has an adhesive layer 2 provided on the opposite surface 12 of the rough surface 11 of the heat radiation layer 1, can release heat from the heat source and the housing with good efficiency by being attached to the heat source and the housing that houses the heat source. As a result, the temperature of the heat source and the internal temperature of the housing can be effectively reduced. That is, the heat-radiating composite film 10 of the present invention is very useful for effectively reducing the temperature of the heat source.

[0062] [Material of the heat radiation layer]

[0063] The material of the heat radiation layer 1 is not particularly limited as long as the heat radiation rate can be ensured to be 0.80 or more. Specifically, it is preferably any one selected from the group consisting of polyester resins, fluororesins, acrylic resins, epoxy resins, polyurethane resins, and olefin resins. The heat radiation layer 1 containing the above materials can exhibit sufficient flexibility. In addition, the heat radiation layer 1 may contain ceramic powders such as silica, alumina, titanium oxide, boron nitride, or particles with a high heat radiation rate such as cordierite powder and graphite for the purpose of increasing the heat radiation rate.

[0064] [Base material layer]

[0065] In the heat-radiating composite film 10 of the present invention, the base material layer 3 is optional. Figure 2 The heat-radiating composite film 10 including the base material layer 3 as shown can exhibit higher strength.

[0066] [Material of the base material layer]

[0067] The material of the base material layer 3 is not particularly limited, and a material that can ensure adhesion to the heat radiation layer 1 is preferred. Specifically, resins the same as those of the heat radiation layer 1 can be exemplified, and polyester resin, fluororesin, acrylic resin, epoxy resin, polyurethane resin, olefin resin, silicone resin, and metal foil are preferred, and metal foil with a thermal conductivity of 200 W / mK or more in the plane direction is more preferred. If such a material is used and the area of the heat-radiating composite film 10 can be made larger than that of the heating element during installation, the base material layer 3 can quickly diffuse the heat from the heating element in the plane direction. As a result, heat can be conducted to the heat radiation layer 1 with good efficiency, and thus the advantage of increasing the area of the heat-radiating composite film 10 can be fully exerted. The thermal conductivity of the base material layer 3 in the plane direction is preferably as high as possible, but in reality, it is, for example, 1,000 W / mK or less.

[0068] In addition, in the present invention, the thermal conductivity of the base material layer 3 is a value calculated by measuring the thermal conductivity using a thermal wave analyzer TA33 / 35 manufactured by BETHEL Co., Ltd.

[0069] [Thickness of the base material layer]

[0070] The thickness of the base material layer 3 is not particularly limited. The total thickness of the heat radiation layer 1 and the base material layer 3 is preferably 30 μm or more and 200 μm or less, and more preferably 50 μm or more and 100 μm or less. In addition, the ratio of the thickness of the heat radiation layer 1 to the thickness of the base material layer 3 is preferably 0.02 or more and 39 or less, and more preferably 0.2 or more and 19 or less. As long as the heat-radiating composite film of the heat radiation layer 1 and the base material layer 3 includes the above relationship, a better balance between excellent heat radiation and high strength can be exhibited.

[0071] [Adhesive layer]

[0072] Since the heat-radiating composite film 10 of the present invention includes the adhesive layer 2, it can be easily applied to the heat source and the housing.

[0073] [Material of the adhesive layer]

[0074] The material of the adhesive layer 2 is not particularly limited. As examples, organic resin polymer matrices such as acrylic resin, silicone resin, polyurethane resin, and epoxy resin can be cited. In addition, a thermally conductive filler can be added to the organic polymer matrix. In addition, the thermal resistance of the adhesive layer is preferably 1.2 cm 2 ·K / W or less. As long as the heat-radiating composite film includes such an adhesive layer 2, heat can be conducted from the heat source to the heat radiation layer 1 with better efficiency. The lower the thermal resistance of the adhesive layer, the better, but in reality, it is, for example, 0.1 cm 2 ·K / W or more.

[0075] In addition, as the material of the adhesive layer 2, a cured product of the following silicone composition is further preferably listed. The following components are essential components of the silicone composition:

[0076] (a) A linear organopolysiloxane having an alkenyl group, which is 100 parts by mass;

[0077] (b) A thermally conductive filler, which is 300 to 900 parts by mass;

[0078] (c) An organohydrogenpolysiloxane, in an amount such that the hydrogen atoms directly bonded to silicon atoms in component (c) are in a molar ratio of 0.5 to 20 with respect to the alkenyl groups in component (a); and

[0079] (d) A platinum group metal-based catalyst, which is 0.1 to 1,000 ppm of component (a) in terms of the mass of the platinum group metal element.

[0080] Hereinafter, each component will be described in detail.

[0081] [(a) Organopolysiloxane having an alkenyl group]

[0082] The organopolysiloxane having an alkenyl group as component (a) of the adhesive layer 2 is the main component of the silicone polymer matrix.

[0083] Component (a) may be an organopolysiloxane having at least 1 alkenyl group bonded to a silicon atom in one molecule, and more preferably an organopolysiloxane having 2 or more alkenyl groups bonded to a silicon atom in one molecule. Generally, the main chain portion is basically composed of repeating diorganosiloxane units, but may also include a branched structure in a part of the molecular structure, or may be a cyclic body. In particular, in terms of physical properties such as the mechanical strength of the cured product, a linear diorganopolysiloxane is preferred. The kinematic viscosity of the organopolysiloxane at 25 °C may be 100 to 50,000 mm 2 / s, more preferably 1,000 to 30,000 mm 2 / s. This kinematic viscosity is a value measured using a Cannon-Fenske viscometer as described in JIS Z 8803:2011.

[0084] The alkenyl group is preferably an alkenyl group having 2 to 8 carbon atoms, and examples thereof include vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, and cyclohexenyl. Among them, lower alkenyl groups such as vinyl and allyl are preferred, and vinyl is particularly preferred.

[0085] As a substituent other than the alkenyl group bonded to a silicon atom, any monovalent hydrocarbon group that is conventionally bonded to the silicon atom of the alkenyl-containing organopolysiloxane may be used. A monovalent hydrocarbon group having 1 to 10 carbon atoms is preferred, a monovalent hydrocarbon group having 1 to 6 carbon atoms is more preferred, and a monovalent hydrocarbon group having 1 to 3 carbon atoms is further preferred. Specific examples include: alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl; aryl groups such as tolyl, xylyl, naphthyl, biphenyl; aralkyl groups such as benzyl, phenethyl, phenylpropyl, methylbenzyl. In addition, groups in which some or all of the hydrogen atoms bonded to the carbon atoms in these groups are substituted with halogen atoms such as fluorine can be cited, for example, 3,3,3-trifluoropropyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl. Methyl, ethyl, propyl, and 3,3,3-trifluoropropyl are particularly preferred. In addition, it is not limited to the case where all functional groups other than the alkenyl group bonded to the silicon atom are the same.

[0086] [(b)Thermally conductive filler]

[0087] The thermally conductive filler incorporated into the adhesive layer 2 is not particularly limited, and the thermally conductive filler may be a single type or a combination of two or more types. Substances generally regarded as thermally conductive fillers such as metals such as copper and aluminum, metal oxides such as alumina, silica, and magnesia, and metal nitrides such as aluminum nitride and boron nitride can be used. In particular, since the heat-radiating composite film requires insulation, metal oxides, aluminum nitride, boron nitride, etc. are preferred, and alumina is more preferred.

[0088] The blending amount of the thermally conductive filler is 300 to 900 parts by mass, preferably 400 to 750 parts by mass, based on 100 parts by mass of the component (a).

[0089] [(c)Organohydrogenpolysiloxane]

[0090] The component (c) is an organohydrogenpolysiloxane, which may have an average of 2 or more, preferably 2 to 100, hydrogen atoms (silyl hydride groups) directly bonded to silicon atoms in one molecule. The component (c) functions as a crosslinking agent for the component (a). Through the hydrosilylation reaction of the silyl hydride groups in the component (c) and the alkenyl groups in the component (a), a three-dimensional network structure with a crosslinked structure is imparted. If the average number of silyl hydride groups is less than 1, curing may not occur. The organohydrogenpolysiloxane may be a conventionally known compound and may be any of linear, branched, and cyclic types.

[0091] As substituents other than the hydrogen atoms bonded to the organohydrogenpolysiloxane, the same substituents as those exemplified as substituents other than alkenyl groups for the component (a) can be mentioned.

[0092] The blending amount of the organohydrogenpolysiloxane is an amount such that the hydrogen atoms directly bonded to silicon atoms (silyl hydride groups) of the component (c) are in a molar ratio of 0.5 to 20 with respect to the alkenyl groups of the component (a), and preferably an amount such that the hydrogen atoms directly bonded to silicon atoms (silyl hydride groups) of the component (c) are in a molar ratio of 1.0 to 10 with respect to the alkenyl groups of the component (a).

[0093] [(d) Platinum group metal-based catalyst]

[0094] (d) The component is a platinum group metal-based catalyst, and any substance that can promote the addition reaction of the alkenyl group derived from the component (a) and the silyl hydride group derived from the component (c) can be used, and catalysts known as catalysts for hydrosilylation reactions can be mentioned. For example, platinum-based metal catalysts include platinum group metal monomers such as platinum (including platinum black), rhodium, and palladium; H 2 PtCl 4 ･nH 2 O, H 2 PtCl 6 ･nH 2 O, NaHPtCl 6 ･nH 2 O, KaHPtCl 6 ･nH 2 O, Na 2 PtCl 6 ･nH 2 O, K 2 PtCl 4 ･nH 2 O, PtCl 4 ･nH 2 O, PtCl 2 , Na 2 HPtCl 4 ･nH 2Platinum chlorides such as O (wherein n is an integer from 0 to 6, preferably 0 or 6), chloroplatinic acid, and chloroplatinate salts; alcohol-modified chloroplatinic acid (refer to the specification of U.S. Patent No. 3,220,972), complexes of chloroplatinic acid and olefins (refer to the specifications of U.S. Patent No. 3,159,601, U.S. Patent No. 3,159,662, and U.S. Patent No. 3,775,452); catalysts obtained by supporting platinum group metals such as platinum black and palladium on carriers such as alumina, silica, and carbon; rhodium-olefin complexes, tris(triphenylphosphine)rhodium chloride (Wilkinson's catalyst); complexes of platinum chloride, chloroplatinic acid, or chloroplatinate salts with vinyl-containing siloxanes, especially with vinyl-containing cyclic siloxanes, etc.

[0095] The amount of component (d) is 0.1 to 1,000 ppm in terms of the mass of the platinum group metal element, more preferably 250 to 750 ppm.

[0096] [(e) Organosilicon resin having a branched structure]

[0097] The organosilicon composition (adhesive) preferably contains, in addition to components (a) to (d), an organosilicon resin having a branched structure as component (e).

[0098] Component (e) can impart cohesiveness to the adhesive. Component (e) has a branched structure and is preferably a copolymer of R 3 SiO 1 / 2 units (M units) and SiO 4 / 2 units (Q units).

[0099] As substituents bonded to the organosilicon resin having a branched structure, the same substituents as those exemplified for component (a) as substituents other than the alkenyl group can be mentioned.

[0100] When blending component (e) with respect to 100 parts by mass of component (a), the blending amount is preferably 50 to 300 parts by mass, more preferably 100 to 250 parts by mass.

[0101] [Thickness of the adhesive layer]

[0102] The thickness of the adhesive layer 2 is not particularly limited, and preferably the thermal resistance of the adhesive layer 2 alone is 1.2 cm 2 ·K / W or less. The thickness of the adhesive layer 2 is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 80 μm or less. As long as the thickness of the adhesive layer 2 is 10 μm or more and 100 μm or less, air mixing can be sufficiently prevented when attached to the heating element, and the heat flow from the heating element is not hindered.

[0103] [Method for Manufacturing Heat Radiation Composite Film]

[0104] For the heat radiation layer 1 of the heat radiation composite film 10 of the present invention, it can be prepared by methods such as roughening the surface by using the pressure transfer method, or after laminating the heat radiation layer 1 on the substrate layer 3 by using the coating method, roughening one side surface 11 of the heat radiation layer 1 by using the sandblasting method, etc. However, the method for preparing the heat radiation layer 1 is not limited to these methods. In addition, as the method for laminating the adhesive layer 2 on the opposite surface 12 of the heat radiation layer 1 or on the surface of the substrate layer 3 opposite to the heat radiation layer 1, the coating method and the bonding method can be cited, but it is not limited to these methods.

[0105] Examples

[0106] Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited thereto.

[0107] [Examples 1 - 4, Comparative Examples 1 - 4]

[0108] Hereinafter, the manufacturing methods of the heat radiation composite films of the examples and comparative examples are described. In addition, the compositions of the heat radiation composite films of the examples and comparative examples are described in Table 1.

[0109] [Heat Radiation Layer and Substrate Layer]

[0110] A - 1

[0111] Heat radiation layer: Acrylic resin (heat dissipation coating manufactured by Pelnox, Ltd., product name: Pelcool, thickness: 50 μm, emissivity: 0.86, spreading area ratio: 1.7, thermal conductivity in the plane direction: 0.1 W / mK)

[0112] Substrate layer: None

[0113] The above heat dissipation coating was coated on a separator coated with a silicone resin release agent by using a comma coater so as to have the above thickness, heated and cured under the conditions of 80°C × 10 minutes, and then heated and cured under the conditions of 120°C × 10 minutes. Then, sandblasting was performed on the surface of the cured film, and it was peeled off from the separator to obtain the above heat radiation layer.

[0114] A - 2

[0115] Heat radiation layer: Acrylic resin (heat dissipation coating manufactured by Pelnox, Ltd., product name: Pelcool, thickness: 30 μm, emissivity: 0.86, spreading area ratio: 1.7, thermal conductivity in the plane direction: 0.1 W / mK)

[0116] Base material layer: Aluminum foil 20μm (Thermal conductivity in the plane direction: 236 W / mK)

[0117] Using a comma coater, coat the above heat dissipation coating on the aluminum foil to achieve the above thickness, heat cure it under the conditions of 80°C × 10 minutes, and then heat cure it under the conditions of 120°C × 10 minutes. Then, perform sandblasting on the surface of the cured film to obtain the above base material layer and the above heat radiation layer formed on this base material layer.

[0118] A-3

[0119] Heat radiation layer: Acrylic resin (Heat dissipation coating manufactured by Pelnox, Ltd., product name: Pelcool, thickness: 30μm, emissivity: 0.86, spreading area ratio: 1.2, thermal conductivity in the plane direction: 0.1 W / mK)

[0120] Base material layer: Aluminum foil 20μm (Thermal conductivity in the plane direction: 236 W / mK)

[0121] Using a comma coater, coat the above heat dissipation coating on the aluminum foil to achieve the above thickness, heat cure it under the conditions of 80°C × 10 minutes, and then heat cure it under the conditions of 120°C × 10 minutes. Then, perform wire drawing on the surface of the cured film to obtain the above base material layer and the above heat radiation layer formed on this base material layer.

[0122] A-4

[0123] Heat radiation layer: Acrylic resin (Heat dissipation coating manufactured by Pelnox, Ltd., product name: Pelcool, thickness: 30μm, emissivity: 0.86, spreading area ratio: 1.0, thermal conductivity in the plane direction: 0.1 W / mK)

[0124] Base material layer: Aluminum foil 20μm (Thermal conductivity in the plane direction: 236 W / mK)

[0125] The above heat radiation layer is obtained by the following method: Using a comma coater, coat the above heat dissipation coating on the aluminum foil to achieve the above thickness, heat cure it under the conditions of 80°C × 10 minutes, and then heat cure it under the conditions of 120°C × 10 minutes. That is, the heat radiation layer A-4 does not have a rough surface.

[0126] [Adhesive layer]

[0127] B-1

[0128] Silicone adhesive 50μm (Thermal resistance: 2.8 cm 2 ·K / W)

[0129] The above-mentioned adhesive layer is obtained by the following method: using a comma coater to coat an addition reaction type silicone adhesive manufactured by Shin-Etsu Chemical Co., Ltd. on a spacer coated with a fluorine-modified silicone resin release agent so as to achieve the above-mentioned thickness, heating and curing under the conditions of 80°C for 3 minutes, and then heating and curing under the conditions of 120°C for 5 minutes.

[0130] B-2

[0131] Silicone adhesive 50μm (Thermal resistance: 0.9cm 2 ·K / W)

[0132] The above-mentioned silicone adhesive is a silicone composition composed of the following components (a) to (g), and is a substance prepared by mixing for 60 minutes at 25°C using a planetary mixer according to the above-mentioned respective components and blending amounts.

[0133] (a) Component: An organopolysiloxane represented by the following formula (1) and having a kinematic viscosity of 30,000 mm 2 / s at 25°C

[0134] [Chemical formula 1]

[0135]

[0136] (m is a number such that the kinematic viscosity at 25°C is 30,000 mm 2 / s)

[0137] Blending amount: 100 parts by mass

[0138] (b) Component: Alumina powder having an average particle size of 1μm and 0.5 mass% of coarse particles of 30μm or more

[0139] Blending amount: 510 parts by mass

[0140] (c) Component: A methylhydrogenpolysiloxane represented by the following average formula (2) and having a silicon atom-bonded hydrogen atom in the side chain

[0141] [Chemical formula 2]

[0142]

[0143] Blending amount: 1.7 parts by mass

[0144] (d) Component: 5 mass% chloroplatinic acid 2-ethylhexanol solution

[0145] Blending amount: 1.0 part by mass

[0146] (e) Component: Substantially composed of (CH 3 )3 SiO 1 / 2 Unit (M unit) and SiO 4 / 2 Unit (Q unit) to form a toluene solution of silicone resin (molar ratio of M unit / Q unit is 1.15) (non-volatile component is 70% by mass; kinematic viscosity at 25 °C is 30 mm 2 / s)

[0147] Blending amount: 175 parts by mass

[0148] (f) Component: 3-methyl-1-tridecyn-3-ol as an addition reaction control agent

[0149] Blending amount: 0.2 parts by mass

[0150] (g) Component: Dimethylpolysiloxane represented by the following formula (3) with an average degree of polymerization of 30 and one end capped with trimethoxysilyl

[0151] [Chemical formula 3]

[0152]

[0153] Blending amount: 14 parts by mass

[0154] The above-mentioned adhesive layer B-2 is obtained by the following method: using a comma coater to coat the above-prepared silicone adhesive on a spacer coated with a fluorine-modified silicone resin release agent so as to have the above thickness, heating and curing under the conditions of 80 °C × 3 minutes, and then heating and curing under the conditions of 120 °C × 5 minutes.

[0155] [Evaluation method of adhesive layer]

[0156] Evaluate the thermal resistance of the adhesive layer by the method shown below. The results are shown in Table 1.

[0157] Clamp the obtained adhesive layer with a diameter of 12.7 mm between two aluminum plates with a diameter of 12.7 mm × a thickness of 1 mm, apply a pressure of 137.9 kPa (20 psi), and place it at room temperature (25 °C) for 60 minutes, and then measure the thermal resistance of the above-mentioned adhesive layer using a thermal resistance measuring instrument based on the laser flash method (LFA447 NanoFlash manufactured by NETZSCH).

[0158] [Manufacturing method of heat-radiating composite film]

[0159] In the manner of forming the structure shown in Table 1, in Example 1 and Example 3, the above-mentioned adhesive layer was laminated on the heat radiation layer, and in Example 2 and 4 and Comparative Examples 1 to 4, the above-mentioned adhesive layer was laminated on the side of the substrate layer opposite to the heat radiation layer. Using a laminating device, a pressure of 0.5 MPa was applied to each of the obtained laminates at room temperature (25°C) for 5 minutes to obtain the heat-radiating composite films of Example 1 to 4 and Comparative Examples 1 to 4. For each of the obtained heat-radiating composite films, a heat radiation test was carried out by the evaluation method shown below. The results are shown in Table 1 together.

[0160] [Evaluation method for heat-radiating composite film]

[0161] ·Heat radiation test

[0162] For the three surfaces of the 15 mm × 15 mm top surface and the 15 mm × 10 mm side surface of a heat source with a width of 15 mm × a length of 15 mm × a height of 10 mm, the heat-radiating composite film was attached in such a way that no air bubbles invaded and all the surfaces were covered with the heat-radiating composite film. 4 W of electricity was applied to the heat source, and then the temperature of the surface of the heat source without the heat-radiating composite film attached was measured after 2 hours. This test assumes a situation where the area of the heat dissipation film is the same as or smaller than the heat source during installation. In addition, the measurement environment was set to 25°C and the humidity was set to 50%.

[0163] [Table 1]

[0164]

[0165] As can be seen from Table 1, in the heat radiation test, regardless of the thermal conductivity of the substrate layer in the surface direction of the substrate layer and the thermal resistance of the adhesive layer, as long as the emissivity of the heat radiation layer is the same, the heat source temperatures of Examples 1 to 4 with a heat radiation layer expansion area ratio of 1.7 are significantly lower than those of Comparative Examples 3 and 4 with a heat radiation layer expansion area ratio of 1.0, and heat radiation is effectively carried out. However, for Comparative Examples 1 and 2 with a heat radiation layer expansion area ratio of 1.2, no clear effect was confirmed compared to Comparative Examples 3 and 4 with a heat radiation layer expansion area ratio of 1.0. That is, it can be known that when the area of the heat-radiating composite film is the same as or smaller than the heating element, regardless of the substrate layer and the adhesive layer, as long as the emissivity of the heat radiation layer is the same, the heat-radiating composite film with a heat radiation layer expansion area ratio of 1.5 or more is suitable for heat radiation.

[0166] Industrial applicability

[0167] The heat-radiating composite film of the present invention is effective in reducing the temperature of the heating element and releasing the heat released by the heating element to the outside of the housing, and can be suitably used for electronic terminals such as smart phones or notebook computers, personal computer servers, etc., for example.

[0168] This specification includes the following solutions.

[0169] [1] A heat-radiating composite film having a heat-radiating layer and an adhesive layer, wherein the heat-radiating composite film is characterized in that

[0170] the thickness of the heat-radiating layer is 5 μm or more and 200 μm or less, one surface of the heat-radiating layer is a rough surface, the emissivity of the rough surface is 0.80 or more, and the spread area ratio is 1.5 or more,

[0171] the adhesive layer is provided on the surface opposite to the rough surface of the heat-radiating layer.

[0172] [2] The heat-radiating composite film according to [1], wherein the heat-radiating layer contains any one selected from the group consisting of polyester resins, fluororesins, acrylic resins, epoxy resins, polyurethane resins, and polyolefin resins.

[0173] [3] The heat-radiating composite film according to [1] or [2], characterized in that there is further one or more substrate layers between the heat-radiating layer and the adhesive layer, and the substrate layer contains any one or more selected from the group consisting of polyester resins, fluororesins, acrylic resins, epoxy resins, polyurethane resins, polyolefin resins, silicone resins, and metal foils.

[0174] [4] The heat-radiating composite film according to [3], characterized in that the total thickness of the heat-radiating layer and the substrate layer is 30 μm or more and 200 μm or less, and the ratio of the thickness of the heat-radiating layer to the thickness of the substrate layer is 0.02 or more and 39 or less.

[0175] [5] The heat-radiating composite film according to [3] or [4], wherein the substrate layer is a metal foil having a thermal conductivity in the plane direction of 200 W / mK or more.

[0176] [6] The heat-radiating composite film according to any one of [1] to [5], characterized in that the thermal resistance of the adhesive layer is 1.2 cm 2 ·K / W or less.

[0177] [7] The heat-radiating composite film according to any one of [1] to [6], characterized in that the adhesive layer contains a thermally conductive filler.

[0178] [8] The heat-radiating composite film according to any one of [1] to [7], characterized in that the adhesive layer is a cured product of a silicone composition, and the silicone composition includes the following components as essential components:

[0179] (a) A linear organopolysiloxane having an alkenyl group, which is 100 parts by mass;

[0180] (b) A thermally conductive filler, which is 300 to 900 parts by mass;

[0181] (c) An organohydrogenpolysiloxane, which is in an amount such that the hydrogen atoms directly bonded to silicon atoms in component (c) are in a molar ratio of 0.5 to 20 with respect to the alkenyl groups in component (a); and

[0182] (d) A platinum group metal-based catalyst, which is 0.1 to 1,000 ppm of component (a) in terms of the mass of the platinum group metal element.

[0183] [9] The heat-radiating composite film according to [8], characterized in that the organosilicon composition further has: (e) an organosilicon resin having a branched structure, which is 50 to 300 parts by mass.

[0184] In addition, the present invention is not limited to the above embodiments. The above embodiments are only examples, and technical solutions having substantially the same constitution as the technical concept described in the claims of the present invention and exhibiting the same technical effects are all included within the protection scope of the present invention.

Claims

1. A heat-radiating composite film having a heat-radiating layer and an adhesive layer, wherein the heat-radiating composite film is characterized in that, the thickness of the heat-radiating layer is 5 μm or more and 200 μm or less, one surface of the heat-radiating layer is a rough surface, the emissivity of the rough surface is 0.80 or more and the spread area ratio is 1.5 or more, the adhesive layer is provided on the surface opposite to the rough surface of the heat-radiating layer.

2. The heat-radiating composite film according to claim 1, wherein, the heat-radiating layer comprises any one selected from the group consisting of polyester resin, fluororesin, acrylic resin, epoxy resin, polyurethane resin and polyolefin resin.

3. The heat-radiating composite film according to claim 1, characterized in that, one or more substrate layers are further provided between the heat-radiating layer and the adhesive layer, and the substrate layer comprises any one or more selected from the group consisting of polyester resin, fluororesin, acrylic resin, epoxy resin, polyurethane resin, polyolefin resin, silicone resin and metal foil.

4. The heat-radiating composite film according to claim 3, characterized in that, the total thickness of the heat-radiating layer and the substrate layer is 30 μm or more and 200 μm or less, and the ratio of the thickness of the heat-radiating layer to the thickness of the substrate layer is 0.02 or more and 39 or less.

5. The heat-radiating composite film according to claim 3, wherein, the substrate layer is a metal foil having a thermal conductivity in the plane direction of 200 W / mK or more.

6. The heat-radiating composite film according to claim 1, characterized in that, The thermal resistance of the adhesive layer is 1.2 cm 2 ·K / W or less.

7. The heat-radiating composite film according to claim 1, characterized in that, the adhesive layer comprises a thermally conductive filler.

8. The heat-radiating composite film according to claim 1, characterized in that, the adhesive layer is a cured product of a silicone composition, and the silicone composition takes the following components as essential components: (a) A linear organopolysiloxane having an alkenyl group, which is 100 parts by mass; (b) A thermally conductive filler, which is 300 to 900 parts by mass; (c) An organohydrogenpolysiloxane, the amount of which is such that the hydrogen atoms directly bonded to the silicon atoms in component (c) are in a molar ratio of 0.5 to 20 with respect to the alkenyl groups in component (a); and (d) A platinum group metal-based catalyst, the mass of which is 0.1 to 1,000 ppm of component (a) in terms of the platinum group metal element.

9. The heat-radiating composite film according to claim 8, characterized in that, the silicone composition further has: (e) A silicone resin having a branched structure, which is 50 to 300 parts by mass.

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