JP2015122360A - Heat diffusing film and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat diffusing film superior in thermal diffusibility.SOLUTION: A heat diffusing film according to the present invention is pasted to the housing of an electronic device in use. The heat diffusing film comprises a layer A of which the thermal emittance is less than 0.5. In the heat diffusing film, the layer A is preferably composed of a laminate having a metal layer and a heat-transmissive layer. In addition, as to the heat diffusing film according to the present invention, it is preferable that the heat transmittance of the heat-transmissive layer is 60% or larger.

Description

  The present invention relates to a heat-diffusing film used by being attached to a casing of an electronic device. Further, the present invention relates to an electronic device in which a heat diffusive film is attached to a housing.

  In an electronic device such as a computer, a tablet, or a smartphone, a component (semiconductor chip or the like) inside the electronic device generates heat during use, and the temperature in the vicinity of the generated component may increase locally. In order to suppress the temperature rise of the electronic device, a heat radiating member or a sheet that diffuses heat may be used.

  There is also known a heat diffusion sheet that is directly attached to an electronic component that generates heat and transmits heat to a heat radiating member, a housing, or the like (Patent Document 1). However, this heat diffusion sheet is a sheet that conducts heat of the heat generating portion in the thickness direction of the heat diffusion sheet, and does not diffuse heat throughout the electronic device by reflection.

  In addition, for example, a heat shielding film that shields light and heat from outside such as sunlight and controls the heat inside the device is known (Patent Document 2). However, this film suppresses the temperature rise inside the device due to light rays and heat from the outside, and does not diffuse the heat caused by the heated electronic components inside the device.

JP 2010-10599 A JP 2012-219168 A

  In some cases, the suppression of heat transmission from the outside or the heat conduction within the sheet alone does not sufficiently diffuse the heat, preventing the temperature rise of the electronic device or the like. Especially in recent years, electronic devices have become smaller and thinner, making it difficult for the heat generated by the electronic components to diffuse inside the electronic devices, resulting in a local increase in temperature around the generated electronic components and a decrease in the performance of the electronic devices. In some cases, the surface temperature of the casing around the heated electronic component becomes locally high, causing low temperature burns when using the electronic device. That is, at present, there is no known sheet having a property (thermal diffusibility) for efficiently diffusing the heat of the generated electronic component throughout the entire interior of the electronic device.

  Accordingly, an object of the present invention is to provide a heat diffusive film having excellent heat diffusibility.

  Thus, as a result of intensive studies by the present inventors, it has been found that excellent thermal diffusivity can be obtained by including a layer having a specific emissivity, and the present invention has been completed.

  That is, the present invention provides a heat-diffusible film having a layer A having an emissivity of less than 0.5 and being used by being attached to a housing of an electronic device.

  The layer A is preferably a laminate having a metal layer and a heat-permeable layer.

  It is preferable that the heat permeable layer has a heat transmittance of 60% or more.

  The layer A is preferably a layer having an uneven structure on the surface.

  The heat diffusive film preferably further has a heat transfer layer and / or a heat insulating layer.

The heat diffusive film preferably has a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more.

  The heat transfer layer is preferably a layer containing thermally conductive particles.

  The heat conductivity of the heat transfer layer is preferably 20 W / m · K or more.

  The heat insulating layer is preferably a foam.

  Moreover, this invention provides the electronic device by which the said heat | fever diffusable film was stuck to the housing.

  Since the heat diffusable film of this invention has the said structure, it is excellent in heat diffusivity.

FIG. 1 is a schematic view (cross-sectional view) showing an example of a heat diffusive film having a layer A in which a heat permeable layer is provided on the entire surface of a metal layer. FIG. 2 is a schematic view (cross-sectional view) showing an example of a heat-diffusing film having a layer A having a heat-permeable layer portion and an electrically insulating layer portion on a metal layer. FIG. 3 is a schematic view (perspective view) of an explanatory diagram of a method for evaluating the rate of temperature increase by attaching a heat diffusive film to the inner surface of the housing of an electronic device. FIG. 4 is a schematic diagram (an XX cross-sectional view of FIG. 3) of an explanatory diagram of a method for evaluating a rate of temperature increase by attaching a heat diffusive film to the inner surface of a casing of an electronic device. FIG. 5 is a schematic diagram (bottom view) of an explanatory diagram of a method for evaluating the thermal diffusibility by attaching a thermal diffusive film to the inner surface of the casing of the electronic device. FIG. 6 is a graph showing the evaluation results of the thermal diffusibility of the examples.

[Heat diffusive film]
The heat-diffusing film of the present invention has at least one layer having an emissivity of less than 0.5 (sometimes referred to as “layer A”). The heat-diffusing film of the present invention may further have a heat transfer layer and / or a heat insulating layer. That is, the heat diffusive film of the present invention may be a single layer film composed only of the layer A, or may be a laminated film having the layer A and the heat transfer layer and / or the heat insulating layer. .

Although it does not specifically limit as a structure of the said laminated | multilayer film, Layer A is a surface layer (When bonding the heat diffusive film of this invention to the housing | casing internal surface of the electronic device which has an electronic component which generate | occur | produces heat, And a layer on the electronic component side that generates heat) is preferably formed. For example, layer A / heat transfer layer, layer A / heat insulating layer, layer A / heat transfer layer / heat insulating layer, layer A / heat insulating layer / transfer Examples of the configuration include a thermal layer. The laminated film may have other layers as long as the effects of the present invention are not impaired.
The “film” in the heat diffusive film of the present invention is a concept including the shapes of “tape”, “sheet” and “film”. Moreover, the heat-diffusible film of this invention may be processed into the shape according to the intended purpose (for example, punching process, cutting process, etc.).

(Layer A)
The layer A is not particularly limited as long as the emissivity is less than 0.5, but is preferably a layer having at least a metal layer, and is a laminate having at least a metal layer and a heat-permeable layer. More preferred. The layer A may further have a layer such as a pressure-sensitive adhesive layer as long as the effects of the present invention are not impaired. Among these, from the viewpoint of further excellent thermal diffusibility, the layer A is preferably a laminate of a metal layer and a heat-permeable layer.

  Although it does not specifically limit as a metal material for forming the said metal layer, For example, simple metals, such as aluminum, silver, gold | metal | money, copper, iron, titanium, platinum, nickel, indium; Gold alloy (for example, gold-copper Alloy), copper alloy (eg, copper-zinc alloy (brass, brass), copper-aluminum alloy, etc.), aluminum alloy (eg, aluminum-molybdenum alloy, aluminum-tantalum alloy, aluminum-cobalt alloy, aluminum-chromium alloy) , Aluminum-titanium alloy, aluminum-platinum alloy, etc.), nickel alloy (eg, nickel-chromium alloy, copper-nickel alloy, zinc-nickel alloy, etc.), stainless steel, magnesium alloy, etc .; ITO (indium tin oxide), etc. Is mentioned. Among these, aluminum, copper, and brass are preferable from the viewpoint of cost and emissivity. The metal material for forming a metal layer can be used individually or in combination of 2 or more types.

  The metal material for forming the metal layer may be a material other than the metal simple substance and the alloy (for example, silicon, metals (for example, alkali metal, alkaline earth), as long as the effects of the present invention are not impaired. Metals, transition metals, aluminum, indium, tin, etc.) oxides, metal hydroxides, metal halides (eg, chlorides), metal oxoacid salts (nitrates, sulfates, phosphates, Carbonate, etc.) may be included.

  From the viewpoint of cost, the metal layer preferably does not contain a material composed of simple carbon (for example, graphite such as graphite or graphite, fullerene, carbon nanotube, carbon fiber, etc.). In particular, graphite sheets (for example, those obtained by mixing graphite powder with a binder resin into a sheet form, those obtained by rolling expanded graphite or the like into a sheet form, etc.) are costly and the material is brittle and peeled off. The metal layer is preferably not a graphite sheet because graphite may cause an electrical circuit in an electronic component to be short-circuited. An alloy containing carbon as a constituent component is not included in a material composed of carbon alone.

  Although the said metal layer is not specifically limited, For example, you may have any forms, such as a metal foil layer and a metal vapor deposition layer. When the metal layer is a metal foil layer, it can be formed, for example, by laminating a metal foil (for example, an aluminum foil, a copper foil, etc.) on the heat-permeable layer via an adhesive layer. Moreover, when it is a metal vapor deposition layer, it can form by vapor-depositing the said metal material (for example, aluminum, copper, brass etc.) on the surface of a heat-permeable layer, for example.

  Although the thickness of the said metal layer is not specifically limited, For example, 1-500 micrometers is preferable, More preferably, it is 50-300 micrometers, More preferably, it is 80-200 micrometers. When the thickness is 1 μm or more, inconveniences such as cracking of the metal layer hardly occur. Low weight can be expected when the thickness is 500 μm or less.

  Although the emissivity of the said metal layer is not specifically limited, For example, it is preferable that it is less than 0.5 (for example, 0 or more and less than 0.5). As the upper limit, for example, 0.45 is preferable, and 0.4 is more preferable. As a lower limit, 0.01 is preferable, for example, More preferably, it is 0.03, More preferably, it is 0.05. When the emissivity of the metal layer is less than 0.5, heat can be reflected more efficiently. In addition, in this specification, an emissivity means what was measured based on JISA1423.

  Although the heat conductivity of the said metal layer is not specifically limited, From a viewpoint of thermal diffusion, 100-420 W / m * K is preferable, for example, More preferably, it is 350-420 W / m * K. In addition, in this specification, heat conductivity means what was measured based on JISA1412-1.

  The heat-transmitting layer is a layer having a property (heat-transmitting property) that transmits incident electromagnetic waves (for example, infrared rays and visible rays). That is, it is a layer having a property of transmitting incident thermal energy. Although the said heat-permeable layer is not specifically limited, For example, it is preferable to form from the composition containing a polyolefin-type polymer from a viewpoint that it is excellent in heat permeability.

The polyolefin polymer has at least an olefin component (ethylene, propylene, butene-1, pentene-1, hexene-1, 4-methyl-pentene-1, heptene-1, octene-1, etc.) as a monomer component constituting the polymer. Of the α-olefin, etc.).
The polyolefin polymer is not particularly limited, and examples thereof include low density polyethylene, linear low density polyethylene (linear low density polyethylene), medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene- α-olefin copolymer (for example, ethylene-propylene copolymer), ethylene-unsaturated carboxylic acid copolymer (for example, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer), ethylene- ( Ethylene such as (meth) acrylic acid ester copolymer (for example, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer), ethylene-vinyl alcohol copolymer, etc. Polymer: polypropylene, propylene-α-olefin copolymer Examples thereof include propylene polymers such as coalescence; polybutene polymers such as polybutene-1; poly-4-methylpentene-1. Among these, polypropylene is preferable from the viewpoints of cost, heat permeability, electrical insulation, and flexibility. The above polyolefin-based polymers can be used alone or in combination of two or more. When the polyolefin-based polymer is a copolymer, it may be a random copolymer or a block copolymer.

  In addition, since a polyester-type polymer has a high heat absorption rate and does not permeate | transmit heat efficiently, it is not preferable as a polymer which comprises a heat-permeable layer. In addition, from the viewpoint of imparting electrical insulation to the heat-diffusing layer, the heat-permeable layer preferably does not contain a conductive substance (for example, a metal component, a polymer having electrical conductivity, etc.). That is, the heat permeable layer preferably has electrical insulation.

  Although the manufacturing method of the said heat-permeable layer is not specifically limited, For example, the method etc. which make the composition containing a polyolefin-type polymer into a film form by the melt film-forming method (T-die method, inflation method, etc.), etc. are mentioned.

  Although the thickness of the said heat-permeable layer is not specifically limited, For example, 1-100 micrometers is preferable. The lower limit is more preferably 3 μm, still more preferably 5 μm. Moreover, an upper limit becomes like this. More preferably, it is 50 micrometers, More preferably, it is 30 micrometers. When the thickness is 100 μm or less, not only excellent heat permeability but also low weight can be expected. Moreover, when the thickness is 20 μm or more, the metal layer is excellent in corrosion prevention effect, and the electrical insulation of the heat diffusible film can be imparted.

  The ratio of the thickness of the metal layer to the thickness of the heat-permeable layer is not particularly limited, but from the viewpoint of further excellent thermal diffusivity, the thickness of the heat-permeable layer is set to the thickness of the metal layer (100 %) Is preferably 5 to 50%, more preferably 5 to 10%.

Although the heat transmittance of the said heat-permeable layer is not specifically limited, For example, 60% or more (for example, 60 to 95%) is preferable, More preferably, it is 85% or more, More preferably, it is 90% or more. When the heat transmittance is 60% or more, electromagnetic waves (such as infrared rays) radiated from the heat source are more easily transmitted through the heat-transmitting layer, and electromagnetic waves reflected by the metal layer are transmitted through the heat-transmitting layer. It becomes easy. In addition, in this specification, heat transmittance means the value calculated | required by the following formulas.
(Heat transmittance) = 1- (emissivity)
In addition, an emissivity says what was measured based on JISA1423.

  The heat transmissivity of the heat permeable layer relative to the emissivity of the metal layer (the heat transmissivity of the heat permeable layer / the emissivity of the metal layer) is not particularly limited, but the viewpoint of further improving the heat reflection efficiency Therefore, it is preferably 2 to 180, more preferably 80 to 180.

  Although the heat absorption rate of the said heat-permeable layer is not specifically limited, For example, 30% or less (for example, 0-30%) is preferable, More preferably, it is 5% or less (for example, 0-5%). When the heat absorption rate is 30% or less, the incident electromagnetic wave is hardly absorbed in the heat-transmitting layer, and the heat-transmitting property is excellent. In addition, in this specification, heat absorption rate means what was measured based on JIS A1423.

  Although the heat conductivity of the said heat-permeable layer is not specifically limited, For example, 20 W / m * K or more is preferable, More preferably, it is 200 W / m * K or more.

  As said adhesive layer in layer A, the adhesive layer used when bonding the said metal layer and the said heat-permeable layer is mentioned, for example. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in the layer A can be appropriately selected within a range not impairing the effects of the present invention. For example, a rubber-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive (acrylic urethane-based pressure-sensitive adhesive), an acrylic-based material Known pressure-sensitive adhesives such as pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, and fluorine-based pressure-sensitive adhesives can be used. The pressure-sensitive adhesives can be used alone or in combination of two or more.

In the layer A, the heat permeable layer may be provided on the entire surface of the metal layer (for example, the entire surface of one surface of the metal layer, such as the flat surface and the back surface), or may be provided in part. It may be. For example, when the heat permeable layer is provided on the entire surface of the metal layer (particularly, the heat diffusibility of the present invention is formed on the inner surface of the casing of an electronic device having an electronic component that generates heat out of the surface of the metal layer. When the film is bonded, the heat-transmitting layer is provided over the entire surface on the side of the electronic component that generates heat), which is excellent in thermal diffusibility. When the heat permeable layer is provided on a part of the metal layer, from the viewpoint of electrical insulation, the part of the metal layer on which the heat permeable layer is not provided is electrically insulated. It is preferable that a layer having a property (sometimes referred to as an “electrically insulating layer”) is provided. In this case, it is preferable that the entire surface of the metal layer is covered with the heat-permeable layer portion and the electrically insulating layer portion. That is, the layer A may be provided with a heat permeable layer 2 on the entire surface of the metal layer 1 as shown in FIG. 1, or the heat permeable layer on the metal layer 1 as shown in FIG. The portion 21 and the portion 3 of the electrically insulating layer may be provided. 1 and 2 are also examples of a single-layer heat-diffusing film composed of only the layer A.
In addition, the said metal layer may be provided with the said heat-permeable layer and the said electrically insulating layer on the whole surface of all the surfaces of the plane of a metal layer, a back surface, and a side surface.

  The electrically insulating layer is a layer having an electrical insulating property different from that of the heat permeable layer. The electrical insulating layer is not particularly limited. For example, at least one selected from the group consisting of polyester polymers (for example, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.), acrylic polymers, and urethane polymers. The layer formed from the composition containing a polymer is mentioned. Among them, a layer made of an inexpensive and electrically insulating material such as polyethylene terephthalate or acrylic polymer is preferable.

  Although the heat absorption rate of the said electrical insulating layer (part of the said electrical insulating layer) is not specifically limited, For example, 0 to 30% is preferable. The upper limit is more preferably 10%, more preferably 5%. That is, the electrical insulating layer is preferably a heat absorbing layer having the insulating properties and heat absorbing properties. Since the heat absorption rate of the above-mentioned electrically insulating layer is 30% or less, for example, in a part where the temperature is likely to rise (for example, a part close to a heat source), heat is transmitted and the metal layer reflects the heat. An electrically insulating layer that can absorb heat directly or indirectly incident from a heat source in a part where the temperature is likely to decrease (for example, a part close to a cooling device). By providing (especially the heat-absorbing layer), heat can be efficiently diffused as a whole.

Although the thickness of the said electrical insulating layer (part of the said electrical insulating layer) is not specifically limited, For example, 1-100 micrometers is preferable. The lower limit is more preferably 5 μm, still more preferably 10 μm. Moreover, an upper limit becomes like this. More preferably, it is 30 micrometers, More preferably, it is 20 micrometers.
In addition, the part in which the said heat-permeable layer was provided, and the part in which the said electrically insulating layer were provided may be the same, or may differ.

  The ratio of the heat permeable layer portion on the metal layer is not particularly limited. For example, the total surface area of the heat permeable layer portion and the electrically insulating layer portion provided on the metal layer (heat permeable property). 50 to 100% is preferable with respect to the total area of the upper surface of the surface portion of the layer portion and the electrically insulating layer portion). The lower limit is more preferably 80%. When the ratio of the heat-permeable layer portion is within the above range, heat can be efficiently reflected and diffused without being excessively absorbed by the portion of the electrically insulating layer. In addition, from the viewpoint of suppressing a local rise in temperature around the heat source, at least near the heat source (for example, a portion including a perpendicular foot drawn from the heat source to the layer A, the measurement point 8 in FIG. 4, etc.). It is preferable that a portion of the heat-permeable layer is provided.

  The shape of the heat permeable layer portion and the shape of the electrically insulating layer portion on the metal layer are not particularly limited, and are, for example, regularly and alternately provided in a stripe shape or a spiral shape. Alternatively, it may be provided irregularly. In the case where a plurality of the heat permeable layer portions and the plurality of electrically insulating layer portions are provided, the respective compositions and thicknesses may be the same or different.

  The method for forming the electrical insulating layer is not particularly limited. For example, a composition containing a polymer component is formed into a film by a melt film formation method (T-die method, inflation method, etc.), and a metal is formed through an adhesive layer. Examples of the method include a method of sticking on a layer, a method of applying a composition containing a polymer component on a metal layer, and the like.

  The layer A is not particularly limited, but is preferably a layer having a concavo-convex structure on the surface from the viewpoint of more excellent thermal diffusibility. The concavo-convex structure provided in the layer A may be provided on the entire surface of the layer A or may be provided in part. Among them, from the viewpoint of reducing the proportion of electromagnetic waves that directly bounce back to the heat source and diffusing heat more efficiently, at least a part including a perpendicular foot that is lowered from the heat source to the layer A is provided with an uneven structure. preferable.

  The shape of each concavo-convex portion of the concavo-convex structure provided on the layer A may be all the same shape, partially the same shape, or all different shapes. The shape of each uneven | corrugated | grooved part may differ regularly, and may differ irregularly. The concavo-convex structure is not limited as long as the surface of the layer A has a surface that is not perpendicular to the heat source, and includes, for example, the case where the layer A is configured obliquely with respect to the heat source.

  Although the manufacturing method of the layer A is not specifically limited, For example, the method of laminating | stacking the said metal layer and the said heat-permeable layer (the said heat-permeable and the said electrically insulating layer) through the said adhesive layer, The said, Examples thereof include a method of forming a metal layer by depositing a metal material on the heat-permeable layer. A method for providing the concavo-convex structure on the layer A is not particularly limited, and examples thereof include embossing with an embossing roll.

The emissivity of the layer A is less than 0.5 (for example, 0 or more and less than 0.5), preferably less than 0.3, more preferably less than 0.2, and still more preferably less than 0.1. Moreover, although the details are not clear, the emissivity of the layer A is, for example, 0 from the viewpoint of absorbing a certain amount of heat reflected by the heat diffusing film and diffusing the heat in a balanced manner inside the housing of the electronic device. Is preferably 0.01 or more, more preferably 0.03 or more, still more preferably 0.05 or more, and particularly preferably 0.07 or more. Since the emissivity is less than 0.5, heat is hardly radiated and easily reflected, so that the thermal diffusivity is excellent. In particular, if the emissivity of layer A is 0.07 or more and less than 0.5, it is possible to absorb a certain amount of heat reflected by the heat-diffusing film and diffuse heat in a balanced manner inside the housing of the electronic device. In some cases, the thermal diffusibility is further improved.
The emissivity of layer A is, for example, the selection of the metal constituting the metal layer, the emissivity of the metal layer, the selection of the material constituting the heat permeable layer, the heat transmittance of the heat permeable layer, the heat permeable layer The thickness of the material to be adjusted, the surface treatment of the heat-permeable layer, etc. can be adjusted.

  Although the thickness of the layer A is not specifically limited, For example, 20-200 micrometers is preferable. The lower limit is more preferably 30 μm, still more preferably 50 μm. Moreover, an upper limit becomes like this. More preferably, it is 150 micrometers, More preferably, it is 120 micrometers. When the thickness is in the above range, it can be used not only in a thin electronic device but also low weight.

(Heat transfer layer)
The heat transfer layer is a layer having a property of conducting heat. Although the said heat-transfer layer is not specifically limited, For example, it is preferable that it is a layer containing heat conductive particle. The heat transfer layer may be an acrylic pressure-sensitive adhesive layer (acrylic pressure-sensitive adhesive layer) containing heat conductive particles. The said heat conductive particle can be used individually or in combination of 2 or more types.

Although it does not specifically limit as said heat conductive particle, For example, a hydrated metal compound is mentioned. The hydrated metal compound has a decomposition start temperature in the range of 150 to 500 ° C., and has a general formula MmOn · XH ₂ O (where M is a metal, m, n is an integer of 1 or more determined by the valence of the metal, X is a compound represented by the formula (1) or a double salt containing the compound. The said hydrated metal compound can be used individually or in combination of 2 or more types.

As the hydrated metal compound in the heat-conductive particles is not particularly limited, for example, aluminum hydroxide _{[Al 2 O 3 · 3H 2} O; or Al (OH) _3], boehmite [Al ₂ O ₃ · H ₂ O; or AlOOH], magnesium hydroxide [MgO.H ₂ O; or Mg (OH) ₂ ], calcium hydroxide [CaO.H ₂ O; or Ca (OH) ₂ ], zinc hydroxide [Zn (OH ₂ ), silicic acid [H ₄ SiO ₄ ; or H ₂ SiO ₃ ; or H ₂ Si ₂ O ₅ ], iron hydroxide [Fe ₂ O ₃ .H ₂ O or 2FeO (OH)], copper hydroxide [Cu (OH) ₂ ], barium hydroxide [BaO · H ₂ O; or BaO · 9H ₂ O], zirconium oxide hydrate [ZrO · nH ₂ O], tin oxide hydrate [SnO · H ₂ O], basic magnesium carbonate [3MgCO ₃ · M _{(OH) 2 · 3H 2 O} ], hydrotalcite _{[6MgO · Al 2 O 3 ·} H 2 O], dawsonite _{[Na 2 CO 3 · Al 2} O 3 · nH 2 O], borax [Na ₂ O · B ₂ O ₅ · 5H ₂ O], zinc borate [2ZnO · 3B ₂ O ₅ · 3.5H ₂ O] and the like.

  As the hydrated metal compound, a general commercially available product can be used. For example, as a commercially available product of aluminum hydroxide, a trade name “Hijilite H-100-ME” (average particle size 75 μm) (manufactured by Showa Denko KK) ), Trade name “Heidilite H-10” (average particle size 55 μm) (Showa Denko), trade name “Heidilite H-32” (average particle size 8 μm) (Showa Denko), trade name “Heidi” Light H-42 ”(average particle size 1 μm) (manufactured by Showa Denko), trade name“ B103ST ”(average particle size 8 μm) (manufactured by Nippon Light Metal Co., Ltd.), and the like. Moreover, as a commercial item of magnesium hydroxide, a brand name "KISUMA 5A" (average particle diameter 1 micrometer) (made by Kyowa Chemical Industry Co., Ltd.) etc. are mentioned.

  Furthermore, examples of the heat conductive particles include metal nitrides such as boron nitride, aluminum nitride, silicon nitride, and gallium nitride; aluminum oxide (alumina), magnesium oxide, titanium oxide, zinc oxide, tin oxide, copper oxide, Examples thereof include metal oxides such as nickel oxide and antimonic acid doped tin oxide. In addition, silicon carbide, silicon dioxide, calcium carbonate, barium titanate, potassium titanate, copper, silver, gold, nickel, aluminum, platinum, carbon black, carbon tube (carbon nanotube), carbon fiber, diamond, etc. .

  A general commercial item can be used for such a heat conductive particle. As a commercial item of boron nitride, a brand name "HP-40" (made by Mizushima alloy iron company), a brand name "PT620" (made by Momentive company), etc. are mentioned, for example. As a commercial item of aluminum oxide, a brand name "AS-50" (made by Showa Denko KK), a brand name "AL-13KT" (average particle diameter 96 micrometers) (made by Showa Denko KK), etc. are mentioned, for example. As a commercial item of antimonic acid dope tin, for example, a brand name "SN-100S" (made by Ishihara Sangyo Co., Ltd.), a brand name "SN-100P" (made by Ishihara Sangyo Co., Ltd.), and a brand name "SN-100D (water dispersion product). (Ishihara Sangyo Co., Ltd.). As a commercial item of titanium oxide, a brand name "TTO series" (made by Ishihara Sangyo Co., Ltd.) etc. are mentioned, for example. As commercial products of zinc oxide, trade name “SnO-310” (manufactured by Sumitomo Osaka Cement Co., Ltd.), trade name “SnO-350” (manufactured by Sumitomo Osaka Cement Co., Ltd.), trade name “SnO-410” (Sumitomo Osaka Cement Co., Ltd.) Manufactured).

  Among these, the thermally conductive particles are preferably hydrated metal compounds and metal oxides, more preferably aluminum hydroxide and alumina, from the viewpoint of thermal conductivity, flame retardancy, and cost.

  The shape of the heat conductive particles is not particularly limited, and may be a bulk shape, a needle shape, a plate shape, or a layer shape. The bulk shape includes, for example, a spherical shape, a rectangular parallelepiped shape, a crushed shape, or a deformed shape thereof.

  Although the average particle diameter of the said heat conductive particle is not specifically limited, For example, 0.1-1000 micrometers is preferable. The lower limit is more preferably 0.2 μm, still more preferably 0.5 μm. Moreover, the upper limit is more preferably 200 μm, still more preferably 150 μm. When the average particle size is 1000 μm or less, the size of the heat conductive particles becomes smaller than the thickness of the heat transfer layer, and the problem that the thickness of the heat transfer layer varies can be suppressed. Moreover, since the heat conductive particles do not protrude from the surface, the appearance is good.

  The heat transfer layer preferably contains two or more kinds of heat conductive particles having different average particle diameters. That is, the heat conductive particles are preferably used in combination of heat conductive particles having a small average particle diameter and heat conductive particles having a large average particle diameter. For example, it is preferable to use a combination of large heat conductive particles having an average particle diameter of 5 μm or more and small heat conductive particles having an average particle diameter of less than 5 μm. Thus, by using together the heat conductive particles having different average particle sizes, the dispersibility of the heat conductive particles can be increased, and the heat transfer layer can be filled with many heat conductive particles. . Further, when the heat conductive particles are packed more densely in the heat transfer layer, a heat conduction path by the heat conductive particles is easily constructed, and there is an effect that the heat conductivity is further improved.

  For the combination of the heat conductive particles having a small average particle diameter and the heat conductive particles having a large average particle diameter, the average particle diameter of the heat conductive particles having a large average particle diameter is obtained from the viewpoint of obtaining better heat conductivity. And a combination in which the difference between the average particle diameter of the heat conductive particles having a small average particle diameter is 20 μm or more (preferably 40 μm or more) is preferable. In addition, said difference is a difference of what has the largest average particle diameter and what has the smallest average particle diameter, when 3 or more types are included.

  Further, when combining the heat conductive particles having a small average particle diameter and the heat conductive particles having a large average particle diameter, the ratio of the heat conductive particles having a small average particle diameter and the heat conductive particles having a large average particle diameter is: Although not particularly limited, from the viewpoint of obtaining higher thermal conductivity, the former: the latter (weight ratio) is preferably 1:10 to 10: 1, more preferably 1: 5 to 5: 1, and still more preferably 1. : 2 to 2: 1.

  Although the content rate of the said heat conductive particle in the said heat-transfer layer is not specifically limited, 40-75 volume% is preferable with respect to the whole volume (100 volume%) of the said heat-transfer layer. The lower limit is more preferably 50% by volume, and still more preferably 55% by volume. Further, the upper limit is more preferably 70% by volume, and still more preferably 65% by volume. When the content rate of the said heat conductive particle is 40 volume% or more, it is excellent in heat conductivity and a flame retardance. Electrical insulation can be exhibited when the content rate of the said heat conductive particle is 75 volume% or less. The unit “volume%” used in the above content ratio can be converted to the unit “weight%” using the density of the heat conductive particles.

  The heat transfer layer is excellent in electrical insulation, and it is not necessary to provide a separate pressure-sensitive adhesive layer when it is bonded to another layer. It is preferably an acrylic pressure-sensitive adhesive layer formed from an acrylic pressure-sensitive adhesive composition containing at least a polymer and heat conductive particles.

  Although the content rate of the acrylic polymer in the said heat-transfer layer is not specifically limited, 15-59.9 volume% is preferable with respect to the heat transfer layer whole quantity (whole volume, 100 volume%). The lower limit is more preferably 20% by volume. The upper limit is more preferably 55% by volume.

  The acrylic polymer is a polymer containing an acrylic monomer (a monomer having a (meth) acryloyl group in the molecule) as a constituent monomer component. The acrylic polymer is preferably a polymer containing (meth) acrylic acid alkyl ester as a constituent monomer component. The above acrylic polymers can be used alone or in combination of two or more.

Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth ) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isoamyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate , Heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, (meth) acrylic acid Decyl, isodecyl (meth) acrylate, undecyl (meth) acrylate , Dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, Examples include (meth) acrylic acid C _1-20 alkyl esters in which the alkyl group has 1-20 carbon atoms, such as nonadecyl (meth) acrylate and eicosyl (meth) acrylate. Among these, (meth) acrylic acid C _2-12 alkyl ester having 2 to 12 carbon atoms in alkyl group is preferable, and more preferably 4 to 9 carbon atoms in alkyl group from the viewpoint of easily balancing the adhesive properties. (Meth) acrylic acid C _4-9 alkyl ester. The said (meth) acrylic-acid alkylester can be used individually or in combination of 2 or more types.

  The ratio of the (meth) acrylic acid alkyl ester to the total monomer component (100% by weight) constituting the acrylic polymer is not particularly limited, but is preferably 60% by weight or more, more preferably 70% by weight or more, and still more preferably. Is 80% by weight or more.

The monomer component constituting the acrylic polymer may further contain a polar group-containing monomer from the viewpoint of obtaining an appropriate adhesive strength. Although it does not specifically limit as said polar group containing monomer, For example, a hydroxyl group containing monomer, a nitrogen containing monomer, a sulfonic acid group containing monomer, a phosphoric acid group containing monomer etc. are mentioned. The polar group-containing monomers can be used alone or in combination of two or more.
In this specification, the polar group-containing monomer refers to a polar group-containing monomer excluding a monomer containing a carboxyl group (a monomer having a polar group excluding a carboxy group or an acid anhydride group in the molecule). .

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, ( Examples include 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl methacrylate. Among them, hydroxyethyl (meth) acrylate and hydroxybutyl (meth) acrylate are preferable from the viewpoints of good dispersibility of the heat conductive particles and good wettability to the adherend. The above hydroxyl group-containing monomers can be used alone or in combination of two or more.

  Examples of the nitrogen-containing monomer include N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) (meth) acrylamide, etc. N-hydroxyalkyl (meth) acrylamides; cyclic (meth) acrylamides such as N- (meth) acryloylmorpholine and N-acryloylpyrrolidine; acyclic (meth) acrylamides such as (meth) acrylamide and N-substituted (meth) acrylamides Is mentioned. Examples of the N-substituted (meth) acrylamide include N-alkyl (meth) acrylamides such as N-ethyl (meth) acrylamide and Nn-butyl (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, N, N-di (n-butyl) (meth) acrylamide, N, N-di (t And N, N-dialkyl (meth) acrylamide such as (butyl) (meth) acrylamide. Further, examples of the nitrogen-containing monomer include N-vinyl-2-pyrrolidone (NVP), N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl- N-vinyl cyclic amides such as 1,3-oxazin-2-one and N-vinyl-3,5-morpholinedione; aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N Monomers having amino groups such as dimethylaminopropyl (meth) acrylate; monomers having a maleimide skeleton such as N-cyclohexylmaleimide and N-phenylmaleimide; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide N-2-ethylhexylitaconimide, N-lauryl Kon'imido and itaconimide monomers such as N- cyclohexyl itaconic imide. The nitrogen-containing monomers can be used alone or in combination of two or more.

  Among them, as the nitrogen-containing monomer, N-hydroxyalkyl (meth) acrylamide, from the viewpoint of imparting appropriate polarity and easily obtaining good adhesive properties such as adhesiveness at the initial stage of bonding, adhesive reliability, N-vinyl cyclic amide, cyclic (meth) acrylamide, and N-substituted (meth) acrylamide are preferable, and N- (2-hydroxyethyl) (meth) acrylamide, N-vinyl-2-pyrrolidone, and N- (meta) are more preferable. ) Acrylylmorpholine, N, N-diethyl (meth) acrylamide.

  Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth And acryloyloxynaphthalene sulfonic acid. The said sulfonic acid group containing monomer can be used individually or in combination of 2 or more types.

  As said phosphate group containing monomer, 2-hydroxyethyl acryloyl phosphate etc. are mentioned, for example. The said phosphate group containing monomer can be used individually or in combination of 2 or more types.

  Although the ratio of the said polar group containing monomer is not specifically limited, 1-30 weight% is preferable with respect to all the monomer components (100 weight%) which comprise the said acrylic polymer. The lower limit is more preferably 2% by weight. The upper limit is more preferably 25% by weight. When the proportion of the polar group-containing monomer is 1% by weight or more, high cohesive force is obtained, and high holding power is easily obtained. On the other hand, when the proportion of the polar group-containing monomer is 30% by weight or less, it is possible to suppress the occurrence of a problem that the cohesive force becomes too high and the adhesiveness decreases.

Although the monomer component which comprises the said acrylic polymer is not specifically limited, It is preferable that a carboxyl group-containing monomer is not included substantially from a viewpoint that it is hard to produce corrosion to a metal layer. Here, the “carboxyl group-containing monomer” is a monomer having one or more carboxyl groups (may be in the form of anhydrides) in one molecule, such as (meth) acrylic acid, itaconic acid, maleic acid, Examples include fumaric acid, crotonic acid, isocrotonic acid, maleic anhydride, itaconic anhydride and the like.
In addition, “substantially free” means that it is not actively blended unless it is inevitably mixed. Specifically, it contains a carboxyl group in the monomer component constituting the acrylic polymer. The monomer content is preferably 0.1% by weight or less, more preferably less than 0.05% by weight, still more preferably less than 0.01% by weight, based on the total amount of monomer components (100% by weight). Say.

  Although the monomer component which comprises the said acrylic polymer is not specifically limited, The monomer which has an alkoxy group may be included from a viewpoint that the wettability of a heat-transfer layer improves and heat can be conducted efficiently. Examples of the monomer having an alkoxy group include 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate. Can be mentioned. The monomer which has the said alkoxy group can be used individually or in combination of 2 or more types.

  The proportion of the monomer having an alkoxy group is not particularly limited, but is preferably 3 to 20% by weight with respect to all monomer components (100% by weight) constituting the acrylic polymer. The lower limit is more preferably 5% by weight. The upper limit is more preferably 15% by weight.

  Although the monomer component which comprises the said acrylic polymer is not specifically limited, From a viewpoint that a crosslinked structure can be introduce | transduced into an acrylic polymer and the cohesion force of a heat-transfer layer can be adjusted, a polyfunctional monomer is included. You may go out. Examples of the polyfunctional monomer include hexanediol (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and pentaerythritol diester. (Meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) Acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, dibutyl (meth) acrylate, hexidyl (meth) acrylate, etc. And the like. The said polyfunctional monomer can be used individually or in combination of 2 or more types.

  Although the ratio of the said polyfunctional monomer is not specifically limited, 0.01-2 weight% is preferable with respect to all the monomer components (100 weight%) which comprise the said acrylic polymer. The lower limit is more preferably 0.02% by weight. The upper limit is more preferably 1% by weight. When the ratio of the polyfunctional monomer is 0.01% by weight or more, it is preferable because a high cohesive force can be obtained and a high holding power can be easily obtained. On the other hand, when the ratio of the polyfunctional monomer is 2% by weight or less, the cohesive force becomes too high, and the occurrence of a problem that the adhesiveness is lowered can be suppressed.

  Other monomer components constituting the acrylic polymer include monomers having an epoxy group such as glycidyl (meth) acrylate and allyl glycidyl ether; monomers having a cyano group such as acrylonitrile and methacrylonitrile; styrene, α-methyl Styrene monomers such as styrene; α-olefins such as ethylene, propylene, isoprene, butadiene, and isobutylene; monomers having an isocyanate group such as 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate; vinyl acetate, vinyl propionate, etc. Vinyl ester monomers; vinyl ether monomers such as vinyl ether; (meth) acrylic acid esters having a heterocycle such as tetrahydrofurfuryl (meth) acrylate; fluorine Monomers having a halogen atom such as (meth) acrylate; monomers having an alkoxysilyl group such as 3-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane; monomers having a siloxane bond such as silicone (meth) acrylate; cyclopentyl (meta ) Acrylate, cyclohexyl (meth) acrylate, bornyl (meth) acrylate, (meth) acrylate having an alicyclic hydrocarbon group such as isobornyl (meth) acrylate; phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl ( It may contain (meth) acrylate having an aromatic hydrocarbon group such as (meth) acrylate and (meth) acrylic acid phenoxydiethylene glycol.

  The acrylic polymer can be obtained by polymerizing the monomer component. Although it does not specifically limit as a polymerization method, For example, solution polymerization, emulsion polymerization, block polymerization, photopolymerization (active energy ray polymerization) etc. are mentioned. Among them, a polymerization method using heat or active energy rays (for example, ionizing radiation such as α rays, β rays, γ rays, neutral beam, electron beams, ultraviolet rays, etc.) is preferable, more preferably a thermal polymerization initiator. A polymerization method using a heat or active energy ray using a polymerization initiator such as a photopolymerization initiator is preferred. In particular, the polymerization method is preferably a polymerization method using active energy rays (particularly ultraviolet rays) using a photopolymerization initiator because of the advantage that the polymerization time can be shortened. The said polymerization initiator can be used individually or in combination of 2 or more types.

  The photopolymerization initiator is not particularly limited. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photo Examples thereof include active oxime photopolymerization initiators, benzoin photopolymerization initiators, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, and thioxanthone photopolymerization initiators. The said photoinitiator can be used individually or in combination of 2 or more types.

  Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, Anisole methyl ether etc. are mentioned. Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4- (t-butyl). ) Dichloroacetophenone and the like. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone and 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one. It is done. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl methyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, decylthioxanthone, and the like.

  Although the usage-amount of the said photoinitiator is not specifically limited, 0.01-5 weight part is preferable with respect to 100 weight part of monomer components which comprise the said acrylic polymer. The lower limit is more preferably 0.05 parts by weight. The upper limit is more preferably 3 parts by weight.

  In the photopolymerization, the irradiation energy, irradiation time, etc. of active energy rays (particularly ultraviolet rays) are not particularly limited. It is only necessary that the photopolymerization initiator is activated to cause the monomer component to react.

  Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis (2-methylpropionic acid) dimethyl, , 4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazoline) -2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) hydrochloride, 2,2 Azo-based polymerization initiators such as' -azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate; Peroxide-based polymerization initiators such as sid, t-butylpermaleate, t-butyl hydroperoxide, hydrogen peroxide; persulfates such as potassium persulfate and ammonium persulfate; persulfates and sodium bisulfite Examples thereof include redox polymerization initiators such as a combination and a combination of peroxide and sodium ascorbate. The said thermal polymerization initiator can be used individually or in combination of 2 or more types.

  Although the usage-amount of a thermal-polymerization initiator is not specifically limited, For example, conventionally, it can select in the range which can be utilized as a polymerization initiator. In the case of polymerization using heat, for example, the monomer component and the thermal polymerization initiator are dissolved in an appropriate solvent (for example, an organic solvent such as toluene or ethyl acetate), and the temperature is high (for example, 20 to 100 ° C. (preferably 40 to Acrylic polymer can be obtained by reacting at 80 ° C.

  The heat transfer layer may contain a crosslinking agent from the viewpoint of improving the cohesive force. The crosslinking agent is not particularly limited, and for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, a silicone crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a silane crosslinking agent, an alkyl etherified melamine crosslinking agent. And metal chelate crosslinking agents. Of these, isocyanate crosslinking agents and epoxy crosslinking agents are preferred. The said crosslinking agent is used individually or in combination of 2 or more types.

  Examples of the isocyanate crosslinking agent include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenyl. Examples include methane triisocyanate, polymethylene polyphenyl isocyanate, and adducts of these with polyols such as trimethylolpropane. Furthermore, “a compound having at least one or more isocyanate groups and one or more unsaturated bonds in one molecule” such as 2-isocyanatoethyl (meth) acrylate is also included.

  Examples of the epoxy crosslinking agent include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, Methylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine and 1,3-bis (N, N′-diamine glycidylaminomethyl) cyclohexane Etc.

  Although content of the said crosslinking agent in the said heat-transfer layer is not specifically limited, 0.01-5 weight part is preferable with respect to 100 weight part of said acrylic polymers. The lower limit is more preferably 0.02 parts by weight. Further, the upper limit is more preferably 3 parts by weight, still more preferably 2 parts by weight. When the content of the crosslinking agent is 0.01 parts by weight or more, the cohesiveness is easily obtained. Further, when the content of the crosslinking agent is 5 parts by weight or less, flexibility is easily obtained.

  Furthermore, the said heat-transfer layer may contain tackifying resin from the point of an adhesive improvement. The tackifying resin is not particularly limited, and examples thereof include petroleum resins, terpene resins, coumarone / indene resins, styrene resins, rosin resins, alkylphenol resins, and xylene resins. The tackifier resins can be used alone or in combination of two or more.

  In particular, when the monomer component constituting the acrylic polymer does not contain a carboxyl group-containing monomer, it is difficult to obtain a high adhesive force, and therefore it is preferable that a tackifier resin is included. The tackifying resin is not particularly limited. However, when an acrylic polymer is obtained by copolymerizing monomer components by irradiating ultraviolet rays, a hydrogenated type adhesive is used because it is difficult to inhibit polymerization even when used together. It is preferable to use an imparting resin. Examples of hydrogenated tackifying resins include derivatives obtained by hydrogenating tackifying resins such as rosin resins, petroleum resins, terpene resins, coumarone-indene resins, styrene resins, alkylphenol resins, xylene resins ( And hydrogenated rosin resins, hydrogenated petroleum resins, hydrogenated terpene resins, and the like. Among these, a hydrogenated rosin resin is preferable. Examples of the hydrogenated rosin-based tackifying resin include modified rosin obtained by modifying unmodified rosin (raw rosin) such as gum rosin, wood rosin and tall oil rosin by hydrogenation.

  The tackifier resin is preferably a tackifier resin having a softening point of 80 to 200 ° C. (preferably 100 to 200 ° C.) from the viewpoint of further increasing the cohesive force.

  The content of the tackifying resin in the heat transfer layer is not particularly limited, but is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer. The lower limit is more preferably 2 parts by weight, still more preferably 3 parts by weight. Moreover, the upper limit is 40 weight part, More preferably, it is 30 weight part. Adhesiveness improves that content of the said tackifying resin is 1 weight part or more. Moreover, the fall of cohesion force can be suppressed as content of the said tackifying resin is 50 weight part or less.

  The heat transfer layer may contain a phosphate ester-based dispersant containing a phosphate triester from the viewpoint of preventing an increase in the dielectric constant due to moisture absorption and hardly causing a decrease in electrical insulation over time.

  Furthermore, the heat transfer layer may contain an acrylic oligomer as long as the effects of the present invention are not impaired. Since the acrylic oligomer functions as a tackifier component, adhesion can be improved.

  Furthermore, the heat transfer layer may contain a silane coupling agent from the viewpoint of improving adhesive strength and durability and improving the affinity between the heat conductive particles and the acrylic polymer. The silane coupling agent is not particularly limited. For example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane and other epoxy group-containing silane coupling agents; 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl Amino group-containing silane coupling agents such as -N- (1,3-dimethylbutylidene) propylamine; (meth) acryl group-containing silanes such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane Coupling agent; 3-iso Inshianeto group-containing silane coupling agent such as A sulfonate triethoxysilane and the like. The said silane coupling agent can be used individually or in combination of 2 or more types.

  The content of the silane coupling agent in the heat transfer layer is not particularly limited, but is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer. The lower limit is more preferably 0.02 parts by weight, still more preferably 0.05 parts by weight. The upper limit is more preferably 5 parts by weight, still more preferably 2 parts by weight. When the content of the silane coupling agent is 0.01 parts by weight or more, an effect of improving affinity is easily obtained, which is preferable. Further, it is preferable that the content of the silane coupling agent is 10 parts by weight or less because the problem of a decrease in thermal conductivity due to the silane coupling agent hardly occurs.

  Furthermore, the heat transfer layer contains additives such as plasticizers, anti-aging agents, colorants (pigments, dyes, etc.), antistatic agents, etc. as long as they do not impair the effects of the present invention. You may go out. Furthermore, air bubbles may be included from the viewpoint of improving the cushioning property and improving the unevenness following property.

  The acrylic pressure-sensitive adhesive composition may have any form, and examples thereof include an emulsion type, a solvent type (solution type), an active energy ray curable type, and a hot melt type (hot melt type). . Among these, a solvent-type acrylic pressure-sensitive adhesive composition and an active energy ray-curable acrylic pressure-sensitive adhesive composition are preferable.

The solvent-type acrylic pressure-sensitive adhesive composition is preferably an acrylic pressure-sensitive adhesive composition containing at least an acrylic polymer and thermally conductive particles. The active energy ray-curable acrylic pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive composition containing at least a monomer mixture or a partial polymer thereof, which is a composition for forming an acrylic polymer, and thermally conductive particles. Preferably there is. Among these, the acrylic pressure-sensitive adhesive composition is preferably an active energy ray-curable acrylic pressure-sensitive adhesive composition from the viewpoint of productivity, environmental aspects, and ease of obtaining a thick pressure-sensitive adhesive layer. In addition, when the said acrylic adhesive composition is an active energy ray hardening-type acrylic adhesive composition, the monomer component may be included with the partial polymer of a monomer mixture.
In this specification, the “monomer mixture” means a mixture of only monomer components, and includes a case of being composed of only one monomer component.

  The heat transfer layer is formed, for example, from the acrylic pressure-sensitive adhesive composition using a known or conventional method. For example, the heat transfer layer is formed by coating the acrylic pressure-sensitive adhesive composition on a suitable support such as a release liner or a substrate to form an acrylic pressure-sensitive adhesive composition layer, The pressure-sensitive adhesive composition layer may be formed by curing (for example, curing with heat or active energy rays). Furthermore, if necessary, in addition to curing, it may be further dried by heating. In addition, since the photopolymerization reaction is easily inhibited by oxygen in the air, curing by active energy rays (photocuring) is performed in an environment where oxygen is blocked by covering with a release liner or by reacting in a nitrogen atmosphere. Preferably it is done.

  Although the thickness of the said heat-transfer layer is not specifically limited, For example, 50-5000 micrometers is preferable from the point of a step absorbency point, the point of an adhesive characteristic, the point of thermal conductivity, or an electrical insulation. The lower limit is more preferably 100 μm, still more preferably 500 μm. Moreover, the upper limit is more preferably 3000 μm, still more preferably 2000 μm, and particularly preferably 1000 μm, from the viewpoint of ease of obtaining a pressure-sensitive adhesive layer having a uniform thickness and workability. The heat transfer layer may have a single layer structure or a laminated structure.

  The thermal conductivity of the heat transfer layer is not particularly limited, but is preferably 20 W / m · K or more (for example, 20 to 1700 W / m · K), more preferably 100 to 1700 W / m · K, and still more preferably. Is 200-1700 W / m · K. When the thermal conductivity is 20 W / m · K or more, the heat transmitted to the heat transfer layer without being reflected by the layer A is efficiently conducted in the heat transfer layer, so that the heat from the heat source is further increased. It can be diffused efficiently.

  By providing the heat transfer layer, the thermal conductivity of the heat diffusive film of the present invention is improved. That is, by providing the heat transfer layer, for example, the temperature rise near the heat source (for example, the portion including the perpendicular foot from the heat source to the layer A, the measurement point 8 in FIG. 4) can be further suppressed. And heat can be dispersed throughout the heat diffusive film.

(Insulation layer)
As said heat insulation layer, the layer which consists of a foam, the layer containing a hollow microsphere, these laminated bodies, etc. are mentioned, for example. Among these, a layer made of a foam is preferable from the viewpoint of excellent heat insulation. Examples of the foam include foams described in JP2012-51984, JP2012-41490, JP2012-51985, and 2012-41491.
The heat insulating layer may be a heat insulating layer having adhesiveness from the viewpoint that it is not necessary to provide a pressure-sensitive adhesive layer when laminating with the layer A or the heat transfer layer.

  The foam is preferably a foam having spherical cells, for example. The “spherical bubble” includes not only a strictly spherical bubble but also a substantially spherical bubble having a partial strain or a bubble composed of a space having a large strain.

  The average pore diameter of the spherical bubbles in the foam is not particularly limited, but is preferably 0.01 μm or more and less than 20 μm, for example. The lower limit is more preferably 0.1 μm, still more preferably 1 μm. Further, the upper limit is more preferably 15 μm, still more preferably 10 μm. When the average pore diameter is within the above range, the average pore diameter of the spherical bubbles can be precisely controlled to be excellent in toughness and heat resistance.

Although the density of the said foam is not specifically limited, For example, 0.15-0.9 g / cm < ³ > is preferable, More preferably, it is 0.15-0.7 g / cm < ³ >, More preferably, it is 0.15-0. 5 g / cm ³ . When the density is within the above range, it is possible to obtain a foam excellent in toughness and heat resistance while widely controlling the density range of the foam.

  The foam may have an open cell structure having a through hole between adjacent spherical cells. The open cell structure may be an open cell structure having through holes between most or all adjacent spherical cells, or may be a semi-independent semi-open cell structure having a relatively small number of through holes.

  Although the average hole diameter of the through-hole which has between adjacent spherical bubbles is not specifically limited, For example, 0.001-5 micrometers or less are preferable. The lower limit is more preferably 0.01 μm. Further, the upper limit is more preferably 4 μm, still more preferably 3 μm. When the average pore diameter of the through-holes between adjacent spherical bubbles is within the above range, the toughness and heat resistance are excellent.

  The foam preferably has a surface opening. Although the average hole diameter of the said surface opening part is not specifically limited, For example, 0.001-5 micrometers is preferable. The lower limit is more preferably 0.01 μm. Further, the upper limit is more preferably 4 μm, still more preferably 3 μm. When the average pore diameter of the surface opening is within the above range, the toughness and heat resistance are excellent.

  The method for producing the foam is not particularly limited. For example, a continuous oil phase component and an aqueous phase component are continuously supplied to an emulsifier to prepare a W / O emulsion, and then the obtained W The “continuous method” is a method in which a water-containing polymer is produced by polymerizing a / O type emulsion, and then the obtained water-containing polymer is dehydrated. Moreover, for example, a W / O type emulsion was prepared by supplying an appropriate amount of an aqueous phase component to the continuous oil phase component in an emulsifier and continuously supplying the aqueous phase component while stirring. There is a “batch method” in which a water-containing polymer is produced by polymerizing a W / O type emulsion, and then the obtained water-containing polymer is dehydrated. Among these, the continuous method is preferable from the viewpoint of production efficiency.

  More specifically, the method for producing the foam includes, for example, a step (I) of preparing a W / O emulsion, a step (II) of shaping the obtained W / O emulsion, and a shaping. It is preferable to include a step (III) of polymerizing the prepared W / O emulsion and a step (IV) of dehydrating the obtained water-containing polymer. Here, at least a part of the step (II) for shaping the obtained W / O emulsion and the step (III) for polymerizing the shaped W / O emulsion may be performed simultaneously.

  The W / O type emulsion used for preparing the foam is not particularly limited. For example, the W / O type emulsion includes a continuous oil phase component and an aqueous phase component immiscible with the continuous oil phase component. Preferably there is. The W / O type emulsion is an emulsion in which a water phase component is dispersed in a continuous oil phase component.

  The aqueous phase component may be any aqueous fluid that is substantially immiscible with the continuous oil phase component. From the viewpoint of ease of handling and low cost, water such as ion exchange water is preferable.

  The aqueous phase component may contain an additive as long as the effects of the present invention are not impaired. Examples of the additive include a polymerization initiator and a water-soluble salt. Among these, water-soluble salts are preferable from the viewpoint of the stability of the W / O emulsion. Examples of the water-soluble salt include sodium carbonate, calcium carbonate, potassium carbonate, sodium phosphate, calcium phosphate, potassium phosphate, sodium chloride, and potassium chloride. The said additive can be used individually or in combination of 2 or more types.

  The ratio (ratio) of the water phase component in the W / O type emulsion is not particularly limited, but is preferably 30 to 95% by weight with respect to the W / O type emulsion (100% by weight), for example. The lower limit is more preferably 40% by weight, still more preferably 50% by weight, and particularly preferably 55% by weight. The upper limit is more preferably 90% by weight, still more preferably 85% by weight, and particularly preferably 80% by weight.

  Although it does not specifically limit as said continuous oil phase component, For example, it is preferable that a hydrophilic polyurethane type polymer and an ethylenically unsaturated monomer are included.

  The hydrophilic polyurethane polymer is not particularly limited. From the viewpoint of obtaining excellent emulsifiability and stationary storage stability without adding an emulsifier, for example, a polyoxyethylene polyoxypropylene glycol-derived polymer is used. It preferably contains oxyethylene polyoxypropylene units. The hydrophilic polyurethane polymer can be obtained, for example, by reacting polyoxyethylene polyoxypropylene glycol with a diisocyanate compound.

  Examples of the polyoxyethylene polyoxypropylene glycol include polyether polyols (ADEKA (registered trademark) Pluronic L-31, L-61, L-71, L-101, L-121, L, manufactured by ADEKA Corporation). -42, L-62, L-72, L-122, 25R-1, 25R-2, 17R-2) and polyoxyethylene polyoxypropylene glycol (Pronon (registered trademark) 052 manufactured by Nippon Oil & Fats Co., Ltd. , 102, 202). The said polyoxyethylene polyoxypropylene glycol can be used individually or in combination of 2 or more types.

  Examples of the diisocyanate compound include aromatic, aliphatic, and alicyclic diisocyanates, dimers and trimers of these diisocyanates, polyphenylmethane polyisocyanate, and the like. Aromatic, aliphatic, and alicyclic diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate. 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4 -Diisocyanate, dicyclohexylmethane-4,4-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methyl Cyclohexane diisocyanate, m- tetramethylxylylene diisocyanate. Examples of the diisocyanate trimer include isocyanurate type, burette type, and allophanate type. Among these, alicyclic diisocyanates are preferable from the viewpoint of rapid urethane reactivity with polyols and suppression of reaction with water. The said diisocyanate compound can be used individually or in combination of 2 or more types.

  The hydrophilic polyurethane-based polymer may have an unsaturated double bond capable of radical polymerization at the terminal.

  The method for preparing the hydrophilic polyurethane polymer is not particularly limited, and examples thereof include a method in which polyoxyethylene polyoxypropylene glycol and a diisocyanate compound are reacted in the presence of a urethane reaction catalyst.

  The ratio of the polyoxyethylene polyoxypropylene glycol and the diisocyanate compound in producing the hydrophilic polyurethane-based polymer is not particularly limited, but is preferably NCO / OH (equivalent ratio) of 1 to 3, for example. The lower limit is more preferably 1.2, still more preferably 1.4, and particularly preferably 1.6. The upper limit is more preferably 2.5, and still more preferably 2. When NCO / OH (equivalent ratio) is less than 1, a gelled product may be easily formed when a hydrophilic polyurethane polymer is produced. When NCO / OH (equivalent ratio) exceeds 3, the amount of residual diisocyanate compound increases and the W / O emulsion may become unstable.

  The hydrophilic polyurethane-based polymer is not particularly limited, but from the viewpoint of stably dispersing the aqueous phase component in the continuous oil phase component, for example, the content ratio of polyoxyethylene in the polyoxyethylene polyoxypropylene unit is 5 to 25% by weight is preferable. The lower limit is more preferably 10% by weight, still more preferably 15% by weight. Further, the upper limit is more preferably 25% by weight, still more preferably 20% by weight. When the said content rate is less than 5 weight%, there exists a possibility that it may become difficult to disperse | distribute a water phase component stably in a continuous oil phase component. When the said content rate exceeds 25 weight%, there exists a possibility of phase-inversion to an O / W type (oil-in-water type) emulsion.

The hydrophilic polyurethane polymer is not particularly limited. For example, the hydrophilic polyurethane polymer is preferably in the range of 10 to 30 parts by weight with respect to 70 to 90 parts by weight of the ethylenically unsaturated monomer, and more preferably, The hydrophilic polyurethane polymer is in the range of 10 to 25 parts by weight with respect to 75 to 90 parts by weight of the ethylenically unsaturated monomer.
Further, the content of the hydrophilic polyurethane polymer in the hydrophilic polyurethane polymer is preferably, for example, 1 to 30 parts by weight, more preferably 1 to 25 parts by weight with respect to 100 parts by weight of the aqueous phase component. It is.

  Although the weight average molecular weight of the said hydrophilic polyurethane type polymer is not specifically limited, For example, 5000-50000 are preferable. The lower limit is more preferably 7000, still more preferably 8000, and particularly preferably 10,000. The upper limit is more preferably 40000, still more preferably 30000, and particularly preferably 20000.

Although it does not specifically limit as said ethylenically unsaturated monomer, For example, (meth) acrylic acid ester is mentioned. Although it does not specifically limit as (meth) acrylic acid ester, For example, the carbon number of an alkyl group is 1-20 (preferably 4-18), (meth) acrylic acid _C1-20 alkyl ester, carbon number is 1 (Meth) acrylic acid ester which has -20 (preferably 4-18) cycloalkyl group is mentioned. The said ethylenically unsaturated monomer can be used individually or in combination of 2 or more types.

_{Examples of the} (meth) acrylic acid C _1-20 alkyl ester include those described above. Of these, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable. The (meth) acrylic acid C _1-20 alkyl ester may be used alone or in combination of two or more.

  Although the content rate of the (meth) acrylic acid ester in the said ethylenically unsaturated monomer is not specifically limited, For example, 80-100 weight% is preferable with respect to ethylenically unsaturated monomer component whole quantity (100 weight%). The lower limit is more preferably 85% by weight. The upper limit is more preferably 98% by weight.

  The ethylenically unsaturated monomer may further contain a polar group-containing monomer, a carboxyl group-containing monomer, and an acid anhydride monomer. The above-mentioned thing is mentioned as said polar group containing monomer. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, ω-carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, itaconic acid, maleic acid. Acid, fumaric acid, crotonic acid and the like can be mentioned. Examples of the acid anhydride monomer include maleic anhydride and itaconic anhydride.

  The content ratio of the polar group-containing monomer in the ethylenically unsaturated monomer is not particularly limited. For example, the content is more than 0% by weight and 20% by weight or less with respect to the total amount of the ethylenically unsaturated monomer component (100% by weight). preferable. The lower limit is more preferably 2% by weight. The upper limit is more preferably 15% by weight.

  The continuous oil phase component may further contain a polymerization initiator. Examples of the polymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone (for example, Ciba Japan, trade name; DAROCURE-2959, in addition to the above-mentioned polymerization initiators. ), Α-hydroxy-α, α′-dimethylacetophenone (for example, Ciba Japan, trade name: Darocur-1173), methoxyacetophenone, 2-hydroxy-2-cyclohexylacetophenone (for example, Ciba Japan) Acetophenone photopolymerization initiator such as Irgacure-184); ketal photopolymerization initiator such as benzyldimethyl ketal; other halogenated ketones; acylphosphine oxide (for example, manufactured by Ciba Japan Co., Ltd.) Trade name; Irgacure-819). The said polymerization initiator can be used individually or in combination of 2 or more types.

  Although the content rate of the said polymerization initiator in the said continuous oil phase component is not specifically limited, For example, 0.05-5.0 weight% is preferable with respect to the whole continuous oil phase component (100 weight%). The lower limit is more preferably 0.1% by weight. The upper limit is more preferably 1.0% by weight. When the said content rate is less than 0.05 weight%, there exists a possibility that the amount of unreacted monomer components may increase and the residual monomer amount in the porous material obtained may increase. When the said content rate exceeds 5.0 weight%, there exists a possibility that the mechanical physical property of the foam obtained may fall.

  In the photopolymerization, the irradiation energy, irradiation time, etc. of active energy rays (particularly ultraviolet rays) are not particularly limited. Since curing with active energy rays may be inhibited by oxygen in the air, for example, an inert gas such as nitrogen is blown into the reaction system before light irradiation, and oxygen is replaced with the inert gas. Or by depressurization treatment.

  The continuous oil phase component further includes “one or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization reactive oligomers” and “weight average molecular weights. One or more selected from polyfunctional (meth) acrylates and polyfunctional (meth) acrylamides having a molecular weight of 500 or less ”may be included. Here, the polyfunctional (meth) acrylate is a polyfunctional (meth) acrylate having at least two ethylenically unsaturated groups in one molecule, and the polyfunctional (meth) acrylamide is at least in one molecule. It is a polyfunctional (meth) acrylamide having two ethylenically unsaturated groups.

  Examples of the polyfunctional (meth) acrylate include 1,10-decanediol, 1,8-octanediol, 1,6 hexane-diol, 1,4-butanediol, 1,3-butanediol, and 1,4. Butane-2-enediol, ethylene glycol, diethylene glycol, trimethylolpropane, pentaerythritol, hydroquinone, catechol, resorcinol, triethylene glycol, polyethylene glycol, sorbitol, polypropylene glycol, polytetramethylene glycol, bisphenol A propylene oxide modified products, etc. Examples thereof include those derived from polyols and bisphenol A.

  Examples of the polyfunctional (meth) acrylamide include diacrylamides, triacrylamides, tetraacrylamides, dimethacrylamides, trimethacrylamides, tetramethacrylamides derived from the corresponding diamines, triamines, tetraamines, etc. Examples include amides.

  Examples of the polymerization reactive oligomer include urethane (meth) acrylate, epoxy (meth) acrylate, copolyester (meth) acrylate, and oligomer di (meth) acrylate. Among these, hydrophobic urethane (meth) acrylate is preferable.

  Although the weight average molecular weight of the said polymerization reactive oligomer is not specifically limited, For example, 1500-10000 are preferable. The lower limit is more preferably 2000 or more.

  “One or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization-reactive oligomers” and “polyfunctional (meth) having a weight average molecular weight of 500 or less When using together with “one or more selected from acrylate and polyfunctional (meth) acrylamide”, “from polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamide, and polymerization reactive oligomer” The amount of “one or more selected” is not particularly limited, but is, for example, from 30 to the total amount (100% by weight) of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component. 100% by weight is preferred. The upper limit is more preferably 80% by weight. When the amount used is less than 30% by weight, the cohesive strength of the resulting foam may be reduced, and it may be difficult to achieve both toughness and flexibility. When the amount used exceeds 100% by weight, the emulsion stability of the W / O type emulsion is lowered, and a desired foam may not be obtained.

  “One or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization-reactive oligomers” and “polyfunctional (meth) having a weight average molecular weight of 500 or less When using together with “one or more selected from acrylate and polyfunctional (meth) acrylamide” “one or more selected from polyfunctional (meth) acrylate and polyfunctional (meth) acrylamide having a weight average molecular weight of 500 or less” Although the usage-amount of is not specifically limited, For example, 1-30 weight% is preferable with respect to the total amount (100 weight%) of the hydrophilic polyurethane type polymer and ethylenically unsaturated monomer in a continuous oil phase component. The lower limit is more preferably 5% by weight. The upper limit is more preferably 20% by weight. When the amount used is less than 1% by weight, the heat resistance may be lowered, or the cell structure may be crushed by shrinkage when the water-containing polymer is dehydrated. When the amount used exceeds 30% by weight, the toughness of the foam is lowered, and the brittleness may be exhibited.

  The continuous oil phase component may contain other components as long as the effects of the present invention are not impaired. Examples of the other components include a catalyst, an antioxidant, and an organic solvent. The said other component can be used individually or in combination of 2 or more types.

  Examples of the catalyst include urethane reaction catalysts such as dibutyltin dilaurate. Arbitrary appropriate content rates can be employ | adopted for the content rate of the said catalyst according to the target catalytic reaction. The said catalyst can be used individually or in combination of 2 or more types.

  Examples of the antioxidant include phenol-based antioxidants, thioether-based antioxidants, and phosphorus-based antioxidants. Arbitrary appropriate content rates can be employ | adopted for the content rate of the said antioxidant in the range which does not impair the effect of this invention. The said antioxidant can be used individually or in combination of 2 or more types.

  Any appropriate organic solvent can be adopted as the organic solvent as long as the effects of the present invention are not impaired. Arbitrary appropriate content rates can be employ | adopted for the content rate of the said organic solvent in the range which does not impair the effect of this invention. The said organic solvent can be used individually or in combination of 2 or more types.

  The method for preparing the continuous oil phase component is not particularly limited. For example, a mixed syrup containing a hydrophilic polyurethane polymer and an ethylenically unsaturated monomer is prepared, and the polymerization syrup is mixed with a polymerization initiator, a crosslinking agent, and the like. The method of mix | blending these components etc. and preparing a continuous oil phase component is mentioned.

  The above W / O type emulsion is a tackifying resin; talc; calcium carbonate, magnesium carbonate, silicic acid and salts thereof, clay, mica powder, aluminum hydroxide, magnesium hydroxide, as long as the effects of the present invention are not impaired. It may contain fillers such as zinc white, bentonine, carbon black, silica, alumina, aluminum silicate, acetylene black, aluminum powder; pigments; dyes and the like.

  The method for producing the W / O type emulsion is not particularly limited. For example, a “continuous method for forming a W / O type emulsion by continuously supplying a continuous oil phase component and an aqueous phase component to an emulsifier. ”Or“ batch method ”in which an appropriate amount of the aqueous phase component is added to the continuous oil phase component in an emulsifier and the aqueous phase component is continuously supplied with stirring to form a W / O type emulsion. Is mentioned.

  The step (II) for shaping the W / O type emulsion is not particularly limited. For example, the W / O type emulsion is continuously supplied onto a running belt to form a smooth sheet on the belt. The method of shaping is mentioned. Further, it may be formed by coating on one surface of a thermoplastic resin film.

  The step (III) for polymerizing the shaped W / O emulsion is not particularly limited. For example, the W / O emulsion is heated on the traveling belt having a structure in which the belt surface of the belt conveyor is heated by a heating device. O type emulsion is continuously fed, a method of polymerizing by heating while forming a smooth sheet on the belt, and a structure in which the belt surface of the belt conveyor is heated by irradiation of active energy rays There is a method in which a W / O emulsion is continuously supplied onto a belt to be polymerized and polymerized by irradiation with active energy rays while forming a smooth sheet on the belt.

  When superposing | polymerizing by heating, superposition | polymerization temperature (heating temperature) is although it does not specifically limit, For example, 23-150 degreeC is preferable. The lower limit is more preferably 50 ° C, further preferably 70 ° C, particularly preferably 80 ° C, and most preferably 90 ° C. Further, the upper limit is more preferably 130 ° C, and even more preferably 110 ° C. When the polymerization temperature is less than 23 ° C., the polymerization takes a long time, and industrial productivity may be reduced. When the polymerization temperature exceeds 150 ° C., the pore size of the obtained foam may be non-uniform or the strength of the foam may be reduced. The polymerization temperature may not be constant. For example, the polymerization temperature may be varied in two stages or multiple stages during the polymerization.

When polymerizing by irradiation with active energy rays, as active energy rays, for example,
Examples include ultraviolet rays, visible rays, and electron beams. Among these, visible to ultraviolet light having a wavelength of 200 to 800 nm is preferable from the viewpoint that light can penetrate through the W / O type emulsion and a suitable photopolymerization initiator and a high string are easily available.

In addition, since active energy ray irradiation is easily inhibited by oxygen in the air, for example, after applying a W / O emulsion on one surface of a substrate such as a thermoplastic resin film and shaping, under an inert gas atmosphere UV rays such as polyethylene terephthalate coated with a release agent such as silicone after passing through a W / O emulsion on one surface of a substrate such as a thermoplastic resin film and shaping, but blocking oxygen It is preferable to carry out by covering the film.
The inert gas atmosphere requires, for example, that oxygen is not present as much as possible, and includes an atmosphere having an oxygen concentration of 5000 ppm or less.

  The thermoplastic resin film is not particularly limited as long as it can be formed by coating a W / O emulsion on one side. For example, a plastic film or sheet such as polyester, olefin resin, or polyvinyl chloride is used. Can be mentioned.

  The dehydration method in step (IV) is not particularly limited, and examples thereof include vacuum drying, freeze drying, press drying, microwave drying, drying in a thermal oven, drying by infrared rays, or a combination of these techniques. Can be mentioned.

  Although the thickness of the said heat insulation layer is not specifically limited, From a heat insulating viewpoint, 20-500 micrometers is preferable, for example. The lower limit is more preferably 30 μm, still more preferably 50 μm. Further, the upper limit is more preferably 400 μm, still more preferably 300 μm. The heat insulating layer may have a single layer structure or a laminated structure.

  Although the heat conductivity of the said heat insulation layer is not specifically limited, For example, 0.01-0.3 W / m * K is preferable, More preferably, 0.01-0.2 W / m * K, More preferably, it is 0.00. 01 to 0.1 W / m · K. A heat insulation effect can be expected when the thermal conductivity is 0.3 W / m · K or less.

(Release liner)
In the heat diffusive film of the present invention, the film surface may be protected by a release liner. The release liner is not particularly limited, and examples thereof include a release liner having a release treatment layer formed on at least one surface of a conventional release paper, a low-adhesive substrate, and a release liner substrate.

  The low-adhesive substrate is not particularly limited. For example, fluorine-based polymers (for example, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer) And low adhesive substrates made of nonpolar polymers (for example, olefinic resins such as polyethylene and polypropylene). .

  The release liner substrate in the release liner in which the release treatment layer is formed on at least one surface of the release liner substrate is not particularly limited. For example, a polyester film such as a polyethylene terephthalate film; a polyethylene film, a polypropylene film Examples include olefin resin films; polyvinyl chloride films; polyimide films; polyamide films such as nylon films; and plastic substrate films (synthetic resin films) such as rayon films. In addition, paper-based substrates such as high-quality paper, Japanese paper, kraft paper, glassine paper, synthetic paper, and top coat paper are also included. Furthermore, what laminated these by lamination, co-extrusion, etc. (2-3 layer composite body) etc. are mentioned.

  The release treatment agent for forming the release treatment layer is not particularly limited, and examples thereof include silicone release treatment agents, fluorine release treatment agents, and long-chain alkyl release treatment agents. In addition, an exfoliation processing agent can be used individually or in combination of 2 or more types.

  The thickness and formation method of the release liner are not particularly limited. The thickness of the release liner is not included in the thickness of the heat diffusive film of the present invention.

  The heat diffusive film of the present invention is not particularly limited, and is produced by a known or conventional method. The heat transfer layer and / or the heat insulation layer are not particularly limited, but may be laminated via an adhesive layer, for example. When the heat transfer layer is an acrylic pressure-sensitive adhesive layer containing heat conductive particles, the heat transfer layer can be directly bonded to the layer A or the adherend. When the heat insulating layer is a foam, since the foam has adsorptivity, the heat insulating layer can be directly bonded to the layer A or the adherend.

  Although the thickness of the heat diffusable film of this invention is not specifically limited, For example, 20-500 micrometers is preferable. The lower limit is more preferably 30 μm, still more preferably 50 μm. Further, the upper limit is more preferably 400 μm, still more preferably 300 μm.

The heat diffusive film of the present invention preferably has electrical insulation. The volume resistivity of the heat diffusive film of the present invention is preferably 1 × 10 ¹⁰ Ω · cm or more (for example, 1 × 10 ¹⁰ to 1 × 10 ¹³ Ω · cm), more preferably 1 × 10 ¹¹ Ω. -It is cm or more. The said volume resistivity says what was measured based on JISC2318.
The volume resistivity can be adjusted, for example, by providing a heat permeable layer or an electrically insulating layer on the surface of the layer A.

  Since the heat diffusible film of the present invention includes the layer A having an emissivity of less than 0.5, the heat diffusive film is excellent in heat diffusibility. When layer A has a metal layer, heat radiated from the heat source (electromagnetic waves such as infrared rays and visible light) is reflected by the metal layer, so that heat is diffused more efficiently than heat conduction in the layer. In addition, local temperature rise around the heat source can be suppressed. Furthermore, when the layer A has a heat-permeable layer and a metal layer, the heat-permeable layer transmits heat, and the transmitted heat is reflected by the metal layer, so that heat can be diffused more efficiently. In addition, since the surface of the metal layer is covered with a heat-permeable layer, the electrical insulation is excellent.

  When the heat diffusive film of the present invention has a heat transfer layer in addition to the layer A, a part of the heat transmitted without being reflected by the layer A is conductively diffused in the heat transfer layer. Can diffuse. Further, when a heat insulating layer is included in addition to the layer A, a part of the heat transmitted without being reflected by the layer A is difficult to conduct in the heat insulating layer. The temperature of the surface of the enclosure near the heat generating electronic component inside the electronic device is not easily raised, and problems such as low temperature burns are less likely to occur when using the electronic device.

  The heat-diffusing film of the present invention is used for application to a casing (an inner surface of a casing) of an electronic device (including electronic components). In particular, it is suitably used for application to a case of an electronic device having components (for example, a CPU, a semiconductor chip, a memory, an SSD, a hard disk, a power supply unit, a DVD drive, a display light source, etc.) serving as a heat source.

[Electronics]
The electronic device of the present invention is an electronic device in which the heat-diffusing film of the present invention is attached to a casing. Examples of the electronic device of the present invention include a computer, a tablet, a smartphone, a car navigation system, a mobile phone, a portable game machine, a digital camera, a digital video camera, an electronic notebook, an electronic dictionary, a communication module, and a TV (various displays such as a liquid crystal television). In addition, electronic components (for example, a hard disk drive, a power supply unit, a DVD drive, a liquid crystal monitor, etc.) inside these electronic devices are included.

  The electronic device of the present invention may include a part that serves as a heat source (for example, a CPU, a semiconductor chip, a memory, an SSD, a hard disk, a power supply unit, a DVD drive, a display light source, etc.) inside the housing. In the electronic device of the present invention, it is preferable that the heat diffusive film of the present invention is attached to a housing (an inner surface of the housing). In particular, it is preferable that the heat diffusible film of the present invention is stuck so that the layer A is on the component side that serves as a heat source. When the layer A of the heat diffusible film of the present invention is a laminate of a metal layer and a heat permeable layer, the component side where the heat permeable layer is a heat source from the viewpoint of further excellent heat diffusibility. It is preferable that the heat-diffusible film of the present invention is stuck so that

  The electronic device of the present invention has an electronic device having components that generate heat during use (for example, a semiconductor chip that generates heat during use) because the heat diffusive film of the present invention is attached to the housing (inner surface of the housing) of the electronic device. Computer), the heat can be efficiently diffused inside the electronic device. The same effect can be obtained even when the heat diffusive film of the present invention is attached to the housing of an electronic component such as a hard disk drive inside the electronic device.

  In the electronic device of the present invention, the heat diffusible film of the present invention may be bonded to the housing through an adhesive layer, for example. Moreover, when the heat-diffusible film of this invention has the said heat-transfer layers, such as an acrylic adhesive layer containing a heat conductive particle, it may be bonded together to the housing via the heat-transfer layer. Moreover, when the heat-diffusible film of this invention has the said heat insulation layers, such as a layer which consists of foams, it may be bonded together by the housing through the heat insulation layer.

  As for the electronic device of this invention, the heat | fever diffusable film of this invention may be stuck to the whole inner surface of the housing of an electronic device, and may be stuck to one part. Since the heat diffusive film of the present invention is excellent in the property of reflecting heat and diffusing to the entire electronic device (whole body), it is excellent even when the pasting area is small as compared with the film that diffuses heat by heat conduction. Can exhibit thermal diffusivity. Although it does not specifically limit as an affixing area of the heat diffusable film of this invention, For example, 30 to 100% is preferable with respect to the total area of the housing inner surface of an electronic device.

  Although the thickness of the electronic device of this invention is not specifically limited, For example, 1-10 mm may be sufficient. The heat diffusive film of the present invention can exhibit excellent heat diffusibility even in a thin electronic device in which it is difficult to provide a cooling device in the electronic device or in a thin electronic device in which air is not easily circulated inside the electronic device.

  Since the heat diffusive film of the present invention is excellent in the property of diffusing heat by reflecting heat, it is not directly attached to a component that becomes a heat source inside the electronic device, but between the heat source and the heat diffusible film. In addition, it is preferable to provide a space in which heat (electromagnetic waves (for example, infrared rays and visible rays)) can be reflected and diffused. For this reason, in the electronic device of the present invention, it is preferable that the component serving as a heat source and the heat diffusive film of the present invention are separated by, for example, 0.1 to 5 mm.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited at all by these.

Example 1
On the trade name “aluminum foil” (manufactured by Sumi Light Aluminum Foil Co., Ltd., thickness: 100 μm) as a metal layer, the following heat insulating layer was bonded with a roller to provide a heat insulating layer having a thickness of 190 μm. This heat insulation layer has adhesiveness. And the heat-diffusible film which has the structure of a heat insulation layer / metal layer was obtained. In the heat diffusible film of Example 1, the metal layer corresponds to the layer A. Moreover, the said heat insulation layer was provided in the whole surface of one surface of a metal layer (layer A).
The heat insulation layer was prepared by the following method.
In a reaction vessel equipped with a condenser, a thermometer, and a stirrer, a monomer solution consisting of 2-ethylhexyl acrylate (manufactured by Toagosei Co., Ltd., hereinafter abbreviated as “2EHA”) as an ethylenically unsaturated monomer 171.9 wt. Parts, 100 parts by weight of Adeka (registered trademark) Pluronic L-62 (molecular weight 2500, manufactured by ADEKA, polyether polyol) as polyoxyethylene polyoxypropylene glycol, and ferric acetylacetone (Nippon Chemical Co., Ltd.) as a urethane reaction catalyst Sangyo Co., Ltd. (trade name “Nursem Ferric”) 0.014 parts by weight and hindered phenolic antioxidant (BASF, trade name “Irganox 1010”) 0.2 parts by weight were added. While stirring, hydrogenated xylylene diisocyanate (manufactured by Takeda Pharmaceutical Co., Ltd., Takenate 600) 1 Was added dropwise .9 parts by weight, it was reacted for 4 hours at 65 ° C.. In addition, the usage-amount of the polyisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.4. Thereafter, 3.7 parts by weight of 2-hydroxyethyl acrylate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “HEA”) was added dropwise and reacted at 65 ° C. for 2 hours to obtain a hydrophilic polyurethane polymer / ethylenically unsaturated. Monomer mixed syrup was obtained.
To 100 parts by weight of the obtained hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup, 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester A-HD-N”) ) (Molecular weight 226) 20 parts by weight, as a reactive oligomer, both ends of a polyurethane synthesized from polytetramethylene glycol and isophorone diisocyanate were treated with HEA, urethane acrylate having an ethylenically unsaturated group at both ends (molecular weight) 3720) 62.5 parts by weight, as a photoinitiator, 0.51 part by weight of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF, trade name “Irgacure TPO”), hindered phenolic antioxidant 1 agent (BASF, trade name “Irganox 1010”) Parts were uniformly mixed, continuous oil phase component (hereinafter, referred to as "oil phase") it was. On the other hand, with respect to 100 parts by weight of the oil phase, 300 parts by weight of ion-exchanged water as an aqueous phase component (hereinafter referred to as “water phase”) is placed in a stirring mixer which is an emulsifier charged with the oil phase at room temperature. A stable W / O emulsion was prepared by continuously supplying dropwise. The weight ratio of the water phase to the oil phase was 75/25.
The obtained W / O emulsion was applied on a base material that had been subjected to a release treatment so that the thickness after light irradiation was 190 μm while stirring at room temperature, and was continuously molded. Further, a polyethylene terephthalate film having a thickness of 38 μm and subjected to a release treatment was placed thereon. This sheet was irradiated with ultraviolet rays having a light illuminance of 125 mW / cm ² (measured with TOPCON UVR-T1 having a peak sensitivity maximum wave of 350 nm) using a metal halide lamp (80 W / cm) to obtain a highly hydrous crosslinked polymer having a thickness of 190 μm. . Next, the top film is peeled off, and the high water content crosslinked polymer is heated at 150 ° C. for 2 minutes, whereby the thickness is 190 μm, the bubble ratio is about 75%, the average spherical bubble diameter is 3.0 μm, A heat insulating layer having an average through-hole diameter of 1 μm and an average surface opening diameter of 2 μm was obtained. The obtained heat insulating layer had a thermal conductivity of 0.04 W / m · K.

(Example 2)
The thickness after drying the heat-permeable layer (trade name “5005VP”, manufactured by LANXESS) on the product name “aluminum foil” (made by Sumi Light Aluminum Foil Co., Ltd., thickness 100 μm) as the metal layer. It was coated with an applicator so as to have a thickness of 7 μm, and a heat-permeable layer was provided on the entire surface of one of the metal layers. Then, the heat insulation layer (heat conduction suppression layer) similar to Example 1 was bonded with the roller on the surface opposite to the surface on which the heat-permeable layer was applied, and a heat insulation layer having a thickness of 190 μm was provided. This heat insulation layer has adhesiveness. And the heat diffusable film which has the structure of a heat insulation layer / metal layer / heat-permeable layer was obtained. In the heat diffusible film of Example 2, the metal layer / heat permeable layer corresponds to the layer A. Further, the heat insulating layer was provided on the entire surface of one surface of the metal layer of the layer A.

(Evaluation)
(Temperature rise rate)
3 and 4 show a method of evaluating the rate of temperature rise by attaching a heat diffusive film (100 mm × 250 mm: area ratio of 50% to the bottom surface of the notebook computer) to the inner surface of the bottom surface of the casing 4 of the notebook computer. It is the schematic of explanatory drawing.
As shown in FIGS. 3 and 4, the thermal diffusibility is such that the layer A is on the CPU side as the heat source on the inner surface of the casing 4 of the electronic device having the substrate 5 provided with the CPU 6 as the heat source. Film 7 was pasted. The heat diffusive film was affixed to a position away from the CPU as a heat source, and the temperature at the measurement point 8 in FIG. 4 was measured. A point closest to the CPU 6 that is a heat generation source on the inner surface of the housing was defined as a measurement point 8.
Without attaching the heat diffusive film, the temperature at the measurement point 8 (temperature before heat generation, (unit: ° C.)) was measured using an infrared thermography (trade name “H2640”, manufactured by Nippon Avionics Co., Ltd.). Thereafter, the CPU was operated for 20 minutes at 100% operation, and the temperature at the measurement point 8 (temperature after heat generation, (unit: ° C.)) was measured. The measurement was performed in an environment at a temperature of 20 to 25 ° C.
The difference between the pre-heat generation temperature and the post-heat generation temperature was defined as “temperature rise without film (unit: ° C.)”. After laminating the heat-diffusible films obtained in the examples, the same evaluation as described above was performed, and the “elevated temperature (unit: ° C.) when laminating the films” of each example was measured.
Thereafter, the temperature increase rate (%) was calculated by the following equation.
Temperature rise rate (%) = (Rise temperature when films are bonded) / (Rise temperature when there is no film) × 100

(Thermal diffusion)
The thermal diffusive film obtained in the example (100 mm × 250 mm: 50% area ratio with respect to the bottom surface of the notebook computer) is pasted on the inner surface of the bottom surface of the casing of the notebook computer 4 in the same manner as the evaluation of the temperature rise rate. (FIGS. 3 and 4). In addition, a notebook personal computer (a notebook personal computer without a film) having no film attached to the inner surface of the casing of the notebook personal computer 4 was also prepared.
The temperature (the temperature before heat generation, (unit: ° C.)) of the bottom surface of each notebook computer was measured using an infrared thermography (trade name “H2640”, manufactured by Nippon Avionics Co., Ltd.). Thereafter, each notebook computer was operated at 100% CPU for 20 minutes, and the bottom surface temperature of the notebook computer was measured using an infrared thermography (trade name “H2640”, manufactured by Nippon Avionics Co., Ltd.). The temperature was measured continuously from the measurement start point 91 to the measurement end point 92 (near the center) along the dotted line shown in FIG. 5 (temperature after heat generation, (unit: ° C.)). The measurement was performed in an environment at a temperature of 20 to 25 ° C. FIG. 5 is a bottom view of the notebook computer in which the heat-diffusing film 7 obtained in the example is attached to the inner surface of the bottom surface of the casing of the notebook computer 4. In FIG. 5, the positions of the heat source CPU 6 and the heat diffusive film 7 are shown.
The position of each measurement point (the ratio of the distance between the measurement start point 91 and each measurement point with respect to the distance between the measurement start point 91 and the measurement end point 92) was obtained from the following equation. The position of the measurement start point 91 is 0, and the position of the measurement end point 92 is 1.
(Position of each measurement point) = (Distance between measurement start point 91 and each measurement point (unit: mm)) / (Distance between measurement start point 91 and measurement end point 92 (unit: mm))
Moreover, the rising temperature ratio of each measurement point was calculated | required as follows. The difference between the post-heat generation temperature and the pre-heat temperature at the measurement point where the temperature was the highest among the temperatures of the bottom surface of the notebook computer without the film attached (increased temperature) was 1. That is, in the notebook personal computer to which no film was attached, the rising temperature ratio at the measurement point where the temperature was the highest was set to 1. And the rising temperature ratio of each measurement point of the notebook personal computer to which the notebook personal computer to which the film was not affixed and the thermal diffusible film obtained in each Example was attached was calculated by the following formula.
Rising temperature ratio at each measurement point = ((Temperature after heat generation at measurement point)-(Temperature before heat generation at each notebook computer)) / ((Temperature rises the most among the temperatures at the bottom of the laptop without film attached) (The temperature after the heat generation at the measuring point)-(The temperature before the heat generation of the laptop without film))
The position of each measurement point is taken on the horizontal axis, the temperature rise ratio at each measurement point is taken on the vertical axis, and the change in the rise temperature ratio is shown in FIG.

(Thermal conductivity)
The thermal conductivity of each layer of the thermally diffusible film obtained in the examples was measured according to JIS A1412-1.

(Emissivity)
The emissivity of each layer of the thermally diffusible film obtained in the examples was measured using an emissometer (trade name “D & S AERD emissivity meter” manufactured by Kyoto Electronics Industry Co., Ltd.).

As can be seen from Table 1, the heat diffusible film of the present invention was able to suppress the temperature rise.
Moreover, as shown in FIG. 6, when the heat diffusible film of this invention was used, the position of the measurement point was 0.7-1 vicinity, and the temperature of the bottom face of a notebook computer was rising. Further, the temperature rise ratio was small near the CPU as the heat source (the position of the measurement point was around 0.3). This indicates that the heat near the heat source diffuses to the surroundings, and the temperature at a position away from the heat source rises. In particular, the heat diffusive film of Example 2 had a small rising temperature ratio and efficiently diffused heat throughout the interior of the notebook computer. From this result, among the heat reflected by the heat diffusive film, there is heat that is randomly reflected inside the housing and incident on the heat diffusible film again, so the emissivity of the layer A is set to an appropriate range. By doing so, it is speculated that heat can be diffused in a well-balanced manner as a whole.
Small and thin electronic devices are extremely susceptible to heat accumulation, so even a slight rise in temperature has a large effect. By using the heat diffusive film of the present invention, the heat of the generated electronic component can be efficiently diffused throughout the interior of the electronic device.
The notebook personal computer used for the evaluation of thermal diffusivity has a fan in the vicinity of the measurement point of 0 to 0.2 (near the CPU as a heat source), and releases heat to the outside. When the position of the measurement point is in the vicinity of 0 to 0.2, heat is released to the outside, so the temperature rise ratio is considered to be low. Although details are unknown, in the heat diffusive film of Example 2, the layer A has an appropriate emissivity and the diffused heat is more easily released to the outside, or the position of the measurement point is 0 to 0.00. In the vicinity of 2, the rising temperature ratio was low.

DESCRIPTION OF SYMBOLS 1 Metal layer 2 Heat permeable layer 21 Heat permeable layer part 3 Electrical insulating layer part 4 Electronic device casing 5 Substrate 6 CPU as heat source
7 Thermal diffusion film 8 Measurement point 91 Measurement start point 92 Measurement end point

Claims (10)

  A heat-diffusing film used by being attached to a casing of an electronic device, characterized by having a layer A having an emissivity of less than 0.5.   The heat-diffusible film according to claim 1, wherein the layer A is a laminate having a metal layer and a heat-permeable layer.   The heat diffusive film according to claim 2, wherein the heat permeable layer has a heat transmittance of 60% or more.   The heat diffusible film according to claim 1, wherein the layer A is a layer having a concavo-convex structure on a surface thereof.   Furthermore, the heat-diffusible film of any one of Claims 1-4 which has a heat-transfer layer and / or a heat insulation layer. The heat-diffusible film according to claim 1, which has a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more.   The heat-diffusing film according to claim 5 or 6, wherein the heat transfer layer is a layer containing heat conductive particles.   The thermal conductivity of the heat transfer layer is 20 W / m · K or more. The heat diffusible film according to any one of claims 5 to 7.   The heat-diffusing film according to claim 5 or 6, wherein the heat insulating layer is a foam.   An electronic device in which the heat-diffusing film according to any one of claims 1 to 9 is attached to a casing.

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