JP2012144638A - Insulation heat radiation film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation heat radiation film that improves thermal conductivity with even a small amount of an inorganic filler and has excellent mechanical properties.SOLUTION: In the insulation heat radiation film 1 including organic particles 2, an inorganic filler 3 having insulation and thermal conductivity, and a cured resin 4, the ratio of the average particle diameter of the organic particle to that of the inorganic filler is adjusted to [the organic particle/the inorganic filler]=1/1 or more. The average particle diameter of the organic particle is in the level of 5-50 μm. The ratio of the average particle diameter of the organic particle to that of the inorganic filler may be [the organic particle/the inorganic filler]=1.5/1 or more. The ratio (weight ratio) of the organic particle to the inorganic filler may be in the level of [the organic particle/the inorganic filler]=1/1-1/5. The ratio of the inorganic filler is in the level of 40-60 wt.% relative to the entire film, and the thermal conductivity may be 2 W/mK or more. The shape of the inorganic filler may be in a plate-like shape, and especially the filler may comprise boron nitride.

Description

  The present invention relates to an insulating heat-radiating film that has insulating properties and thermal conductivity, and is used for electrical and electronic devices, and a method for manufacturing the same.

  In order to release the heat generated from the heat generating member (for example, CPU of a personal computer) of electric devices such as electric / electronic parts, a heat conductive film is interposed as a heat radiating member between the heat generating member and the housing. ing. This thermally conductive film is composed of a matrix resin (binder resin) and a thermally conductive inorganic filler, but the binder resin has a lower thermal conductivity than inorganic materials such as metal materials. For this reason, the trial which improves the heat conductivity of a heat conductive film is made | formed by mix | blending a heat conductive inorganic filler with a high ratio with respect to binder resin. Furthermore, the electric device preferably has insulating properties from the viewpoint of preventing troubles with respect to electric circuits and the like, and an insulating inorganic filler is used as the inorganic filler. However, in such a heat conductive film, when the proportion of the inorganic filler is increased in order to improve the heat conductivity, the mechanical properties and moldability of the film are lowered. In particular, boron nitride is widely used as the insulating inorganic filler. However, since boron nitride is in the form of plate-like particles, it is arranged so that the plate surface is parallel to the flow direction of the resin during molding when thermoformed. To do. Further, it is known that boron nitride itself has extremely low thermal conductivity in the thickness direction as compared to the surface direction. Therefore, in the heat dissipation sheet using boron nitride, although the thermal conductivity in the surface direction is high, the thermal conductivity in the thickness direction is low. In particular, in the case of a CPU of a personal computer, since the CPU and the heat dissipation sheet are stacked and installed in the electronic component, it is necessary to release heat in the thickness direction of the sheet. Sheets arranged in the plane direction are not suitable for such applications. Therefore, various composite materials have been proposed as composite materials for satisfying these characteristics.

  For example, JP-A-3-200377 (Patent Document 1) discloses a heat dissipation sheet in which two types of thermally conductive fillers, a plate-like thermally conductive filler and a granular thermally conductive filler, are distributed in a matrix resin. The plate-like thermally conductive filler is distributed in a multistage shape in the thickness direction in a state where the plate surface of the plate is along the longitudinal direction of the heat dissipation sheet, and the granular heat conductive filler is distributed in a multistage shape. There is disclosed a heat dissipating sheet that is distributed mainly between layers of plate-like thermally conductive fillers. In this document, boron nitride is described as the plate-like thermally conductive filler, and aluminum nitride is described as the granular thermally conductive filler. Furthermore, examples of the matrix resin include synthetic rubber, thermoplastic resin, and thermosetting resin. In the examples, silicone rubber is used.

  However, in this heat radiating sheet, although the thermal conductivity in the thickness direction is improved by combining the granular filler aluminum nitride in addition to the plate-like filler boron nitride, the ratio of the inorganic filler is large. The mechanical properties and moldability are not sufficient.

  In addition, Polymer Preprints, Japan. Vol. 58, No. 2 (2009) (Non-Patent Document 1) discloses a honeycomb composite with a highly thermally conductive nanofiller phenol resin. This document describes a method in which boron nitride particles surface-modified with alkoxysilane and phenol resin particles are mixed in an aqueous system in the presence of an epoxy group ring-opening catalyst, and then water is evaporated under vacuum heating.

  However, this honeycomb composite has low molding processability, and requires many steps to obtain a desired cured product, resulting in low productivity.

Japanese Patent Laid-Open No. 3-200377 (Claims, page 2, lower right column, lines 6 to 10, line)

Polymer Preprints, Japan. Vol.58, No.2 (2009)

  Accordingly, an object of the present invention is to provide an insulating heat-radiating film that can improve thermal conductivity even with a small amount of inorganic filler and is excellent in mechanical properties, and a method for producing the same.

  Another object of the present invention is to provide an insulating heat-radiating film having high moldability and productivity and a method for producing the same.

  Still another object of the present invention is to provide an insulating heat-radiating film that can improve thermal conductivity in the thickness direction even when a plate-like inorganic filler is used, and a method for producing the same.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have combined organic particles, an inorganic filler having a particle size equal to or smaller than the average particle size of the organic particles, and a cured resin with a thermally conductive inorganic filler. The present inventors have found that the mechanical properties of the insulating heat-radiating film can be improved and that the thermal conductivity can be improved even with a small amount of inorganic filler.

  That is, the insulating heat dissipation film of the present invention is an insulating heat dissipation film containing organic particles, an inorganic filler, and a cured resin, and the inorganic filler has insulating properties and thermal conductivity. The ratio of the average particle diameter is organic particles / inorganic filler = 1/1 or more. The average particle diameter of the organic particles may be about 5 to 50 μm, and the ratio of the average particle diameter of the organic particles and the inorganic filler may be organic particles / inorganic filler = 1.5 / 1 or more. The ratio (weight ratio) between the organic particles and the inorganic filler may be organic particles / inorganic filler = 1/1 to 1/5. The ratio (weight ratio) between the cured resin and the organic particles may be about 2/1 to 1/2. The proportion of the inorganic filler may be about 100 to 500 parts by weight with respect to 100 parts by weight of the cured resin. The ratio of the inorganic filler may be about 40 to 60% by weight with respect to the entire film, and the thermal conductivity of the inorganic filler may be 2 W / m · K or more. The inorganic filler may be plate-shaped, and in particular boron nitride. The organic particles may be polyamide particles and / or crosslinked thermoplastic resin particles. The cured resin may be a cured product of a thermosetting resin (for example, epoxy resin) and a curing agent. The insulating heat dissipation film of the present invention may further contain a plasticizer. The insulating heat-radiating film of the present invention may be fixed with a cured resin in a state where the inorganic fillers are in contact with each other and are localized between the organic particles.

  The present invention also includes a method for producing the insulating heat dissipation film in which a film of a composition containing organic particles, an inorganic filler, and a cured resin precursor is formed, and then the cured resin precursor is cured. In this method, the composition may be prepared using a solvent capable of dissolving or dispersing the precursor of the cured resin and insoluble in the organic particles.

  In the present invention, a combination of organic particles, an inorganic filler having an insulating and thermal conductivity having a particle size equal to or smaller than the average particle size of the organic particles, and a cured resin can be used to heat even a small amount of inorganic filler. The conductivity can be improved, and the mechanical properties of the insulating heat dissipation film can be improved. Moreover, since high heat conductivity is realizable with a small amount of inorganic filler, a moldability and productivity can also be improved. Furthermore, thermal conductivity can be improved in the thickness direction even if a plate-like inorganic filler is used.

FIG. 1 is a schematic cross-sectional view of the insulating heat-radiating film of the present invention. FIG. 2 is a scanning electron micrograph of boron nitride used in Example 1.

[Insulating heat dissipation film]
The insulating heat dissipation film of the present invention contains organic particles, an inorganic filler, and a cured resin. In the insulating heat-radiating film of the present invention, the inorganic filler has insulating properties and thermal conductivity, and is localized between organic particles in the film to form a heat conduction path or path (channel or path). is doing. FIG. 1 is a schematic cross-sectional view of the insulating heat-radiating film of the present invention. As shown in FIG. 1, the insulating heat-radiating film 1 of the present invention is such that the inorganic filler 3 is localized in contact with each other between the organic particles 2 dispersed substantially uniformly in the film, and the cured resin 4 It is fixed. That is, the inorganic filler 2 can improve thermal conductivity even if it is a small amount of inorganic filler by forming a network structure between the organic particles 3 in the film. In particular, when the inorganic filler 3 is a plate-like inorganic filler such as boron nitride, in the gap between the organic particles, the plate surface of the plate-like filler is oriented along the gap, so that the heat conduction path along the plate surface. By forming the thermal conductivity in the thickness direction of the film can be improved.

(Organic particles)
Organic particles are blended in order to localize the inorganic filler by being dispersed almost uniformly in the film, and according to the mechanical properties (heat resistance, rigidity, elasticity, etc.) required for the insulating heat dissipation film Thus, it can be appropriately selected from resin particles and rubber particles. In the present invention, by using the organic particles, the flexibility of the film can be improved, and the adhesive properties with the curable resin can be enhanced to improve the mechanical characteristics.

  The resin particles include thermoplastic resin particles, crosslinked thermoplastic resin particles, and thermosetting resin particles. Examples of the thermoplastic resin constituting the thermoplastic resin particles include olefin resins, (meth) acrylic resins, styrene resins, fatty acid vinyl ester resins, polyester resins, polyamide resins, polyamideimide resins, and polyacetals. Resin, polycarbonate resin, polysulfone resin, polyphenylene ether resin, thermoplastic polyurethane resin, thermoplastic elastomer (polyolefin elastomer, polystyrene elastomer, polyester elastomer, polyamide elastomer, polyurethane elastomer, etc.), cellulose derivatives, etc. Is mentioned. The crosslinked thermoplastic resin particles may be a crosslinked body of the thermoplastic resin, etc., and depending on the type of the thermoplastic resin, a crosslinked body obtained by using a conventional crosslinking agent, or an active energy such as an electron beam. It may be a cross-linked product obtained using a wire. Examples of the thermosetting resin constituting the thermosetting resin particles include phenol resin, melamine resin, urea resin, benzoguanamine resin, silicone resin, epoxy resin, vinyl ester resin, and polyurethane resin.

  Examples of the rubber constituting the rubber particles include diene rubber (polybutadiene, polyisoprene, styrene-butadiene rubber, etc.), ethylene-propylene rubber, ethylene-vinyl acetate rubber copolymer, butyl rubber, nitrile rubber, chlorosulfonated polyethylene. , Epichlorohydrin rubber, polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber, fluorine rubber and the like.

  These organic particles can be used alone or in combination of two or more. Among these organic particles, organic particles having bonds or groups showing polarity such as amide bonds and ester bonds, and organic particles having a skeleton similar to the cured resin (for example, When the cured resin is an epoxy resin, organic particles having an aromatic skeleton, etc.) are preferred. From the viewpoint of production, organic particles having solvent resistance insoluble in a solvent capable of dissolving or dispersing the precursor of the cured resin (a solvent used for preparing the precursor) are preferable.

  Furthermore, when the curable resin is a thermosetting resin, organic particles having heat resistance capable of maintaining the particle shape at the curing temperature are preferable. When the organic particles are thermoplastic resin particles, the melting point of the thermoplastic resin particles is, for example, about 80 to 300 ° C, preferably 100 to 280 ° C, more preferably 120 to 250 ° C (particularly 150 to 220 ° C). There may be.

  Organic particles having these characteristics include thermoplastic resins such as polyamide resins, polyamideimide resins, and polyacetal resins, crosslinked thermoplastic resins such as crosslinked (meth) acrylic resins and crosslinked polystyrene resins, and epoxy resins. Particles composed of the above thermosetting resin are preferable, and polyamide-based particles and crosslinked poly (meth) acrylate-based particles are particularly preferable.

  Examples of the polyamide constituting the polyamide particles include aliphatic polyamides such as polyamide 46, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11 and polyamide 12, dicarboxylic acids (eg terephthalic acid, isophthalic acid, adipine). And polyamides obtained from diamines (for example, hexamethylenediamine, metaxylylenediamine). These polyamides are not limited to homopolyamides and may be copolyamides.

Examples of the poly (meth) acrylic acid ester constituting the crosslinked poly (meth) acrylic acid ester-based particles include poly (meth) acrylic acid C _1-6 such as poly (meth) ethyl acrylate and poly (meth) butyl acrylate. _Examples thereof include poly (meth) acrylic acid alkyl ester resins containing alkyl (particularly C _2-6 alkyl) as a main component (about 50 to 100% by weight, preferably about 70 to 100% by weight). As the crosslinking agent, a conventional crosslinking agent can be used. For example, a compound having two or more ethylenically unsaturated bonds ((poly) C ₂₋ such as ethylene glycol di (meth) acrylate and polyethylene glycol di (meth) acrylate) is used. ₁₀ alkylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, divinylbenzene, etc.) can be used. The proportion of the crosslinking agent may be about 0.1 to 10 mol% (particularly 1 to 10 mol%) of all monomers. You may improve a softness | flexibility using bridge | crosslinking polyacrylic acid ester particle | grains.

Among these organic particles, when the cured resin is epoxy, aliphatic polyamides having C _8-16 alkylene chains (particularly, aliphatic polyamides having C _10-14 alkylene chains such as polyamide 11 and polyamide 12), etc. Polyamide-based particles, crosslinked thermoplastic resin particles such as crosslinked poly (meth) acrylic acid alkyl ester and crosslinked polystyrene are widely used.

  Examples of the shape of the organic particles include a spherical shape, an ellipsoidal shape, a polygonal shape (polygonal pyramid shape, a rectangular parallelepiped shape, a rectangular parallelepiped shape, etc.), a plate shape or a scale shape, a rod shape, and an indefinite shape. Of these shapes, an isotropic shape such as a substantially spherical shape is preferred from the viewpoint that a uniform and highly heat-conductive channel can be easily formed in the film. Therefore, the average aspect ratio (major axis / minor axis ratio) of the organic particles is, for example, about 1 to 5, preferably about 1 to 2, and more preferably about 1 to 1.5 (particularly 1 to 1.2). .

  The average particle size of the organic particles can be selected from the range of about 1 to 100 μm depending on the particle size of the inorganic filler and the thickness of the film, for example, 1 to 50 μm, preferably 2 to 40 μm, more preferably 3 to 30 μm. It is about (especially 4-25 micrometers).

  The ratio (weight ratio) between the cured resin and the organic particles described later can be selected from the range of cured resin / organic particles = 10/1 to 1/10, for example, 3/1 to 1/3, preferably 2 / 1/1/2, more preferably about 1.5 / 1 to 1 / 1.5 (particularly 1.2 / 1 to 1 / 1.2).

(Inorganic filler)
As an inorganic filler, what is necessary is just to have insulation and thermal conductivity, for example, nitrogen compounds (boron nitride, aluminum nitride, silicon nitride, carbon nitride, titanium nitride, etc.), carbon compounds (silicon carbide, fluorine carbide, Boron carbide, titanium carbide, tungsten carbide, diamond, etc.), metal oxides (silica, alumina, magnesium oxide, zinc oxide, beryllium oxide, etc.) and the like. These inorganic fillers can be used alone or in combination of two or more. Of these inorganic fillers, nitrogen compounds such as boron nitride and aluminum nitride are preferable, and boron nitride is particularly preferable from the viewpoint of excellent insulation and thermal conductivity. Boron nitride may be a hexagonal type having a structure similar to graphite or a cubic type having a diamond structure, but is effective for the hexagonal type in the present invention.

  Examples of the shape of the inorganic filler include particulate (powder), plate (or scale), fiber, and indefinite shape. Among these shapes, a plate-like filler is preferable because the gap between the organic particles can be used as a heat conduction path. The shape of these particles may be those in which primary particles having a smaller average particle size are aggregated to form secondary particles. In this case, the average particle size and shape are the average particle size of the secondary particles. Shows the shape.

  The average particle size of the inorganic filler can be appropriately selected from the range of about 0.1 to 50 μm according to the particle size of the organic particles, and is, for example, 0.1 to 30 μm, preferably 0.5 to 20 μm, more preferably 1 to It is about 15 μm (particularly 2 to 10 μm). When the inorganic filler is plate-shaped, the average particle diameter may be the average diameter of the plate surface (added average diameter of the major axis and the minor axis on the plate surface). Furthermore, when it is plate-like, the aspect ratio (average diameter / thickness of the plate surface) of the average diameter and thickness of the plate surface is, for example, 2 or more, preferably 2 to 50, more preferably 3 to 30 (especially About 5-20) may be sufficient.

  In order for inorganic fillers to contact each other in the gap between organic particles to form a channel (particularly because the plate surface of the plate-like inorganic filler is oriented along the gap), the average particle size of the organic particles and the inorganic filler The ratio can be selected, for example, from a range of about organic particles / inorganic filler = 1/1 to 10/1 (for example, 1.1 / 1 to 25/1). In the present invention, as described above, it is important that the inorganic fillers contact each other in the gap between the organic particles to form a channel. For this reason, the average particle diameter of the organic particles needs to be at least equal to or larger than the average particle diameter of the inorganic filler. For this reason, the lower limit in the ratio of the average particle diameter of the organic particles and the inorganic filler may be organic particles / inorganic filler = 1/1 or more, preferably 1.5 / 1 or more, more preferably 2.1. / 1 or more. The upper limit of the ratio of the average particle size of the organic particles to the inorganic filler is not particularly limited from the viewpoint that the inorganic filler is in contact with each other in the gap between the organic particles to form a channel, but the particle size of the organic particles is extremely high If it is too large, the smoothness of the surface of the resulting heat-dissipating sheet may be impaired. For this reason, the upper limit may be organic particles / inorganic filler = 25/1 or less, preferably 10/1 or less, more preferably 5/1 or less (particularly 4/1 or less). The ratio of the average particle diameter of the particles and the inorganic filler is: organic particles / inorganic filler = 1.5 / 1 to 5/1, preferably 2.1 / 1 to 4/1, more preferably 2.5 / 1 to It may be 3.5 / 1. In the present invention, by using an inorganic filler having a particle size smaller than that of the organic particles, the inorganic filler contacts in the gap between the organic particles. Can be improved.

  The proportion of the inorganic filler can be selected from a range of about 10 to 1000 parts by weight with respect to 100 parts by weight of the cured resin, for example, 100 to 500 parts by weight, preferably 150 to 400 parts by weight, and more preferably 180 to 300 parts by weight. It may be about (particularly 200 to 250 parts by weight).

  The ratio (weight ratio) between the organic particles and the inorganic filler can be selected from the range of about organic particles / inorganic filler = 1 / 0.1 to 1/10. From the viewpoint of improving thermal conductivity, organic particles / inorganic Filler = 1/1 to 1/5, preferably 1 / 1.2 to 1/4, more preferably 1 / 1.5-1 to 1/3 (particularly 1 / 1.8 to 1 / 2.5). is there. In particular, in the present invention, when the inorganic filler is a plate-like inorganic filler such as boron nitride, a film containing an inorganic filler of about 1.5 to 3 times (particularly 1.8 to 2 times) the organic particles is In order to effectively orient the plate-like inorganic filler in the gap between the organic particles, it exhibits particularly high thermal conductivity (for example, thermal conductivity of 3 W / m · K or more) and is more than 3 times that of the organic particles. It exhibits higher thermal conductivity than a film containing a large amount (for example, about 3 to 5 times) of an inorganic filler.

  Furthermore, the ratio of the said inorganic filler can be selected from the range of about 1 to 90 weight% with respect to the whole film, for example, 10 to 80 weight%, Preferably it is 30 to 70 weight%, More preferably, it is 40 to 60 weight% (Especially 45 to 55% by weight). In particular, by adjusting the ratio of the inorganic filler to about 40 to 60% by weight, for example, the thermal conductivity can be improved to 2 W / m · K or more.

(Cured resin)
The cured resin is, for example, a resin cured by heat or active energy rays (such as ultraviolet rays or electron beams), and is usually a cured product of a curable resin and a curing agent. The cured resin fixes the network structure by curing and bonding the organic particles and the inorganic filler in the network structure formed by localizing the inorganic filler in the gaps between the organic particles.

  The precursor of the cured resin is a compound having a functional group that reacts with heat, active energy rays, or the like, and can be variously cured or crosslinked with heat, active energy rays, or the like to form a resin (particularly a cured or crosslinked resin). A curable compound can be used as a precursor of the cured resin. The precursor of the curable resin may be a photocurable resin such as an ultraviolet curable resin or an electron beam curable resin, but a thermosetting resin is preferable from the viewpoint of productivity and adhesiveness.

  Examples of the thermosetting resin include thermosetting acrylic resins, unsaturated polyester resins, epoxy resins, melamine resins, phenol resins, silicone resins, polyimide resins, urethane resins, and the like. Among these, a thermosetting acrylic resin and an epoxy resin are preferable from the viewpoint of excellent adhesive strength, and an epoxy resin is particularly preferable from the viewpoint of exhibiting high adhesive strength to both organic particles and inorganic fillers.

  Examples of the epoxy resin include conventional epoxy resins such as glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, alicyclic epoxy resins, glycidyl amine type epoxy resins, and long chain aliphatic epoxy resins. Of these, glycidyl ether type epoxy resins are widely used because they are excellent in adhesiveness and dimensional stability.

Examples of glycidyl ether type epoxy resins include bisphenol type epoxy resins [for example, epoxy resins having a bis (hydroxyphenyl) C _1-10 alkane skeleton such as bisphenol A type, bisphenol F type, and bisphenol AD type epoxy resins, and bisphenol S type epoxy. Resin etc.], novolac type epoxy resin (eg phenol novolak type, cresol novolak type epoxy resin etc.), aliphatic type epoxy resin (eg hydrogenated bisphenol A type epoxy resin, propylene glycol mono to diglycidyl ether, pentaerythritol mono To tetraglycidyl ether), monocyclic epoxy resin (for example, resorcing ricidyl ether), heterocyclic epoxy resin (for example, triglycidyl isocyanurate). And hydantoin type epoxy resin), tetrakis (glycidyloxyphenyl) ethane and the like.

  Examples of the curing agent include amine-based curing agents [for example, aliphatic polyamines (ethylenediamine, diethylenetriamine, triethylenediamine, tetraethylenepentamine, diethylaminopropylamine, hexamethylenediamine, etc.), alicyclic polyamines (isophoronediamine, etc.), Aromatic polyamines (such as xylenediamine)], polyaminoamide-based curing agents (for example, polycondensates of polyethylene polyamines and fatty acids), acid and acid anhydride-based curing agents [for example, aliphatic carboxylic acid anhydrides (dodecenyl anhydride) Succinic acid and the like), alicyclic carboxylic acid anhydrides (such as methyltetrahydrophthalic anhydride), aromatic carboxylic acid anhydrides (such as phthalic anhydride), and the like. These curing agents can be used alone or in combination of two or more. Among these curing agents, amine-based curing agents such as the above-mentioned amine-based curing agents or modified products thereof (epoxy addition products, acrylonitrile addition products, ethylene oxide addition products, Mannich reaction products, Michael reaction products, thiourea reaction products, etc.) Particularly preferred is a modified product of an aliphatic amine-based curing agent.

  The proportion of the curing agent can be selected from a range of about 1 to 100 parts by weight with respect to 100 parts by weight of the curable resin (for example, epoxy resin) according to the type of the curable resin, for example, 10 to 90 parts by weight, The amount is preferably 20 to 80 parts by weight, more preferably about 30 to 70 parts by weight (particularly 40 to 60 parts by weight).

(Plasticizer)
The insulating heat dissipation film of the present invention may contain a plasticizer in order to improve the affinity between the organic particles and the cured resin and the flexibility of the film.

  The plasticizer can be selected according to the type of organic particles and cured resin. For example, phthalic acid esters (dibutyl phthalate, dioctyl phthalate, etc.), phosphoric acid esters (tricresyl phosphate, trioctyl phosphate, etc.), Carboxylic acid esters (dioctyl adipate, dioctyl sebacate, etc.), epoxy compounds (alkyl epoxy stearate, epoxidized soybean oil, etc.), polyols (diglycerin, polyglycerin, polyethylene glycol, polypropylene glycol, etc.), etc. It is done. These plasticizers can be used alone or in combination of two or more. Among these plasticizers, when the cured resin is an epoxy resin, polyols such as polyethylene glycol, particularly polyethylene glycol is preferred. The weight average molecular weight of polyethylene glycol is, for example, about 100 to 6000, preferably about 200 to 3000, and more preferably about 300 to 1000 (particularly about 500 to 800).

  The ratio of the plasticizer can be selected from the range of about 1 to 1000 parts by weight with respect to 100 parts by weight of the cured resin, for example, 5 to 100 parts by weight, preferably 10 to 50 parts by weight, and more preferably about 15 to 30 parts by weight. It may be. In particular, a plasticizer may be used in an amount of 100 parts by weight or more (for example, about 100 to 200 parts by weight) with respect to 100 parts by weight of the cured resin without using a solvent.

  The thermal conductivity of the insulating heat-radiating film of the present invention may be 1.9 W / m · K or more, for example, 2 to 5 W / m · K, preferably 2.5 to 4.8 W / m · K, More preferably, it may be about 3 to 4.5 W / m · K (particularly 3.5 to 4 W / m · K).

The insulating heat-radiating film of the present invention has excellent insulating properties, and the volume resistivity is, for example, 10 ⁶ Ω · cm or more, preferably 10 ⁷ Ω · cm or more, more preferably 10 ⁸ Ω · cm or more. May be.

  Insulating heat-radiating films are further made of conventional additives such as stabilizers (thermal stabilizers, UV absorbers, light stabilizers, antioxidants, etc.), dispersants, antistatic agents, colorants, flame retardants, lubricants. An agent or the like may be contained. These additives can be used alone or in combination of two or more.

  The thickness of the insulating heat dissipation film can be selected depending on the application, for example, can be selected from a range of about 1 to 1000 μm, for example, 5 to 500 μm, preferably 10 to 400 μm, more preferably 30 to 300 μm (particularly 50 to 200 μm). )

[Insulating heat dissipation film manufacturing method]
The insulating heat-radiating film of the present invention can be obtained by forming a film of a composition containing organic particles, an inorganic filler, and a cured resin precursor, and then curing the cured resin precursor. As a preparation method of the composition, as described above, by increasing the proportion of the plasticizer, the composition may be prepared without using a solvent, but both mechanical properties and thermal conductivity can be achieved. From the viewpoint of easy production of a film, it is preferable to prepare a composition using a solvent that can dissolve or disperse a precursor of a cured resin and insoluble organic particles. As a preparation method of a composition, the method of mixing each component using a conventional mixer (mixer) may be sufficient, for example.

  Examples of the solvent include ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.). ), Aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), water, alcohols (ethanol, isopropanol, butanol, Cyclohexanol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether (1-methoxy-2-propanol), etc.), cellosolve acetates, sulfoxides (dimethylsulfoxy) Etc.), amides (dimethylformamide, dimethylacetamide, etc.), and others.

  These solvents can be used alone or in combination of two or more. In the present invention, among these solvents, the cured resin precursor is dissolved or dispersed in order to maintain the particle shape of the organic particles and to uniformly adhere the cured resin precursor to the organic particles and the inorganic filler. Solvents that are possible and insoluble in organic particles are used. In the present invention, by using such a solvent, the organic particles maintain the particle shape in the film forming step, so that the liquid composition containing the cured resin precursor and the inorganic filler is uniformly distributed between the organic particles. A network structure in which inorganic fillers are localized between organic particles can be formed.

  The solvent used for the precursor of the cured resin can be appropriately selected according to the type of the cured resin and the organic particles. For example, when the cured resin is an epoxy resin and the organic particles are polyamide particles, ketones (particularly methyl ethyl ketone) Dialkyl ketones), aromatic hydrocarbons (especially aromatic hydrocarbons such as toluene), or a mixed solvent thereof may be used.

  When the composition uses a solvent, the solid content may be, for example, about 10 to 70% by weight, preferably 30 to 65% by weight, more preferably about 40 to 60% by weight.

  As a method for forming the film, a method of coating on a substrate (for example, release paper) using a conventional method such as a bar coater or a knife coater can be used.

  The curing method is selected according to the type of cured resin, and a conventional method can be used.In the case of a thermosetting resin, heat treatment may be performed according to the type of resin, and in the case of a photocurable resin, It may be cured by irradiating with active energy. In the thermosetting resin, for example, the curing temperature may be, for example, about 50 to 200 ° C, preferably 60 to 150 ° C, and more preferably about 70 to 100 ° C.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the electroconductivity of the insulating heat-radiating film obtained in the Example was measured with the following method.

(Thermal conductivity)
The thermal diffusivity in the thickness direction of the film was measured using a laser flash thermal conductivity measuring apparatus (manufactured by NETZSCH), and the thermal conductivity was determined based on the following formula.

Thermal conductivity (W / m · K) = density (g / cm ³ ) × specific heat (J / kg · K) × thermal diffusivity (mm ² / s)

Example 1
7 parts by weight of epoxy resin (bisphenol A type liquid epoxy resin, "jER828" manufactured by Mitsubishi Chemical Corporation), 3 parts by weight of curing agent (modified aliphatic polyamine, "jER Cure ST12" manufactured by Mitsubishi Chemical Corporation), polyamide 12 Particles (average particle size 20 μm, melting point 180 ° C.) 10 parts by weight, boron nitride (“GP” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 8 μm, aspect ratio 2 or more) 34 parts by weight, plasticizer (Wako Pure Chemical Industries, Ltd.) 2 parts by weight of “PEG 600” manufactured by Co., Ltd. and 44 parts by weight of solvent (methyl ethyl ketone) were mixed using a self-revolving mixing deaerator (“ARE-250” manufactured by Shinky Co., Ltd.), and the composition was mixed. Produced. The obtained composition was coated on release paper using a bar coater (# 90) and dried at a temperature of 60 ° C. for 30 minutes. Then, after hardening at 80 degreeC for 3 hours, it peeled from the release paper and obtained the 100-micrometer-thick cured film. Scanning electron micrographs (3000 times) of boron nitride (“GP” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 8 μm) are shown in FIG. 2, and as is apparent from FIG. The inorganic particles are in the form of a plate.

Example 2
A cured film was obtained from the composition in the same manner as in Example 1 except that the addition amount of boron nitride was 23 parts by weight and the addition amount of the solvent was 38 parts by weight.

Example 3
7 parts by weight of epoxy resin (jER828), 3 parts by weight of curing agent (jER Cure ST12), crosslinked polyacrylic acid ester particles (“Techpolymer ARX-15” manufactured by Sekisui Plastics Co., Ltd., average particle size 15 μm) 20 weights Part, 20 parts by weight of boron nitride (GP), and 15 parts by weight of a plasticizer (PEG 600) were mixed using a self-revolving mixing and defoaming machine (ARE-250) to prepare a composition. Using the obtained composition, a cured film having a thickness of 100 μm was obtained in the same manner as in Example 1.

Comparative Example 1
A cured film was obtained from the composition in the same manner as in Example 1 except that polyamide 12 particles were not added.

Comparative Example 2
A cured film was obtained from the composition in the same manner as in Example 2 except that polyamide 12 particles were not added.

Comparative Example 3
A cured film was obtained from the composition in the same manner as in Example 1 except that polyamide 12 having an average particle diameter of 5 μm was used as polyamide 12 particles.

  Table 1 shows the measurement results of the conductivity of the cured films obtained in the examples and comparative examples.

  As is clear from the results in Table 1, the cured films of the examples show high thermal conductivity, whereas the cured films of the comparative examples have low thermal conductivity.

  The conductive heat dissipation film of the present invention can be used for various applications requiring insulation and thermal conductivity. For example, electrical / electronic parts (heat dissipation plates, semiconductor elements) such as image display devices, computers, lighting equipment, batteries, etc. , Thermoelectric conversion elements, photoelectric conversion elements, electromagnetic wave absorbing / dissipating materials, substrates, separators, etc.), and particularly useful as heat sinks for computer CPUs, power modules, LEDs, and the like.

DESCRIPTION OF SYMBOLS 1 ... Insulating heat dissipation film 2 ... Organic particle 3 ... Inorganic filler 4 ... Curing resin

Claims (15)

  An insulating heat dissipation film comprising organic particles, an inorganic filler, and a cured resin, wherein the inorganic filler has insulating properties and thermal conductivity, and a ratio of an average particle size between the organic particles and the inorganic filler is organic particles / inorganic Insulating heat dissipation film with filler = 1/1 or more.   The insulating heat-radiating film according to claim 1, wherein the average particle diameter of the organic particles is 5 to 50 μm, and the ratio of the average particle diameter of the organic particles and the inorganic filler is organic particles / inorganic filler = 1.5 / 1 or more. .   The insulating heat-radiating film according to claim 1 or 2, wherein a ratio (weight ratio) between the organic particles and the inorganic filler is organic particles / inorganic filler = 1/1 to 1/5.   The insulating heat-radiating film according to claim 1, wherein a ratio (weight ratio) between the cured resin and the organic particles is 2/1 to 1/2.   The insulating heat-radiating film according to any one of claims 1 to 4, wherein a ratio of the inorganic filler is 100 to 500 parts by weight with respect to 100 parts by weight of the cured resin.   The insulating heat-radiating film according to any one of claims 1 to 5, wherein the proportion of the inorganic filler is 40 to 60% by weight with respect to the entire film, and the thermal conductivity of the inorganic filler is 2 W / m · K or more. .   The shape of an inorganic filler is plate shape, The insulating heat-radiating film in any one of Claims 1-6.   The insulating heat-radiating film according to any one of claims 1 to 7, wherein the inorganic filler is boron nitride.   The insulating heat-radiating film according to claim 1, wherein the organic particles are polyamide-based particles and / or crosslinked thermoplastic resin particles.   The insulating heat-radiating film according to claim 1, wherein the cured resin is a cured product of a thermosetting resin and a curing agent.   The insulating heat-radiating film according to claim 10, wherein the thermosetting resin is an epoxy resin.   Furthermore, the insulating thermal radiation film in any one of Claims 1-11 containing a plasticizer.   The insulating heat-radiating film according to any one of claims 1 to 12, which is fixed with a cured resin in a state where the inorganic fillers are in contact with each other and are localized between the organic particles.   The method for producing an insulating heat-radiating film according to claim 1, wherein after forming a film of a composition containing organic particles, an inorganic filler, and a precursor of a cured resin, the precursor of the cured resin is cured.   15. The method according to claim 14, wherein the composition is prepared using a solvent capable of dissolving or dispersing the precursor of the cured resin and insoluble organic particles.