JP2015067713A - Heat release sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat release sheet excellent in thermal conductivity and comprehensively in cold heat resistance and moist heat resistance, and capable of being used not only for fixing and heat releasing lighting devices using light emission diode (LED), electroluminescence, lighting devices for backlight, solar cells, cells such as lithium ion battery, computer components such as IC and CPU, electrical power controllers such as modules, power supply circuits such as inverters, touch panels, electromagnetic shields, components in electronic devices required to be thin and used for smart phones, tablet terminals, wireless power supplies or the like, but also for graphite sheets, metallic foils, processed products thereof or the like.SOLUTION: There is provided a heat release sheet containing heat release material containing an adhesive resin, an inorganic filler and a curing agent.

Description

  The present invention relates to a heat dissipation sheet. More specifically, the present invention relates to a heat dissipation sheet that can be suitably used for, for example, an electronic device. In addition, in this specification, a heat radiating sheet is a thing of the concept containing a heat radiating tape. Moreover, in this specification, a heat radiating sheet is a thing of the concept including the heat radiating adhesive sheet which has adhesiveness, and the heat radiating sheet which does not have adhesiveness.

  In general, a sheet made of a resin composition in which a heat-conductive filler such as alumina or silica is blended with a flexible resin may have a non-smooth surface such as a heating element or a radiator that uses the sheet. Therefore, in order to follow these surfaces, the sheet is required to have flexibility.

  As a heat conductive material having flexibility, silicone is used as a base material, and a heat conductive material filled with a semiconductor heat conductive filler (see, for example, Patent Document 1), alumina powder, zinc oxide powder, silicone gel, and A thermally conductive material containing an alkylalkoxysilane (see, for example, Patent Document 2) has been proposed. However, the use of silicone and silicone gel is practically limited because the low molecular weight siloxane compound contained therein causes poor connection of electronic components and the like.

  By the way, an electronic device may be used repeatedly in a wide temperature range from high temperature to low temperature, or may be used in a high-temperature and high-humidity atmosphere. Therefore, heat dissipation sheets used in electronic devices are required to have not only thermal conductivity but also cold and moisture resistance.

JP 2003-197833 A JP 2011-084221 A

  This invention is made | formed in view of the said prior art, and it aims at providing the thermal radiation sheet | seat excellent not only in heat conductivity but excellent in cold-heat resistance and wet heat resistance.

  The present invention relates to a heat dissipation sheet made of a heat dissipation material containing an adhesive resin, an inorganic filler, and a curing agent.

  The heat dissipating material used in the present invention further contains an aliphatic carboxylic acid ester from the viewpoint of improving the heat conductivity and the cold and heat resistance, and per 100 parts by mass of the nonvolatile content of the adhesive resin. The amount of the aliphatic carboxylic acid ester is 1.5 to 130 parts by mass, the inorganic filler is preferably plate-like inorganic particles and / or spherical inorganic particles, and the inorganic filler is plate-like inorganic particles and spherical inorganic particles. It is more preferable that

  When the heat-radiating sheet of the present invention is formed of a heat-dissipating material containing an adhesive resin, an inorganic filler, and a curing agent, the heat-dissipating sheet not only has excellent thermal conductivity but also has an effect of being excellent in cold and moisture resistance. . Moreover, the heat dissipation sheet of the present invention further contains an aliphatic carboxylic acid ester, and the amount of the aliphatic carboxylic acid ester per 100 parts by mass of the nonvolatile content of the adhesive resin is 1.5 to 130 parts by mass, When the inorganic filler is a plate-like inorganic particle and / or a spherical inorganic particle, and particularly when the plate-like inorganic particle and the spherical inorganic particle are used in combination as the inorganic filler, the thermal conductivity is further improved, and the heat resistance and moisture resistance are improved. There is an excellent effect that the thermal property can be further improved.

  As described above, the heat dissipation sheet of the present invention is made of a heat dissipation material containing an adhesive resin, an inorganic filler, and a curing agent.

  Examples of the adhesive resin include (meth) acrylic adhesive resin, silicone adhesive resin, urethane adhesive resin, vinyl alkyl ether adhesive resin, vinylpyrrolidone adhesive resin, acrylamide adhesive resin, Cellulose-based adhesive resins, rubber-based heat dissipation sheets, and the like can be mentioned, but the present invention is not limited to such examples. These adhesive resins may be used alone or in combination of two or more, as long as the object of the present invention is not impaired.

  Among adhesive resins, (meth) acrylic adhesive resin is excellent in adhesiveness and constant load peelability, can be used for various adherends, and has a wide range of versatility. (Meth) acrylic adhesive resin obtained by polymerizing a monomer component mainly composed of (meth) acrylic acid alkyl ester is more preferable.

  In this specification, “(meth) acrylic adhesive resin” means “acrylic adhesive resin” or “methacrylic adhesive resin”, and acrylic adhesive resin and methacrylic adhesive resin are respectively It may be used alone or in combination. “(Meth) acrylic acid alkyl ester” means “acrylic acid alkyl ester” or “methacrylic acid alkyl ester”, and acrylic acid alkyl ester and methacrylic acid alkyl ester may be used alone or in combination. Also good.

  The “monomer component mainly composed of (meth) acrylic acid alkyl ester” means that the content of (meth) acrylic acid alkyl ester in the monomer component is 50% by mass or more. The content of the (meth) acrylic acid alkyl ester in the monomer component is 50% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more, from the viewpoint of improving adhesiveness, cold / heat resistance and wet heat resistance. More preferably, it is 80 mass% or more. In addition, the upper limit of the content of the (meth) acrylic acid alkyl ester in the monomer component is preferably 100% by mass, but other than the (meth) acrylic acid alkyl ester as long as the object of the present invention is not impaired. A monomer may be included.

  Among (meth) acrylic acid alkyl esters, they are excellent in adhesiveness, can be used for various adherends, and have a wide range of versatility, from the viewpoint of obtaining (meth) acrylic adhesive resins. (Meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the ester is preferable, and alkyl alkyl ester having 1 to 18 carbon atoms in the alkyl ester is more preferable. Suitable alkyl (meth) acrylates include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec- Butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl acrylate, n-heptyl ( (Meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (Meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, isomyristyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, n-stearyl (meth) acrylate, iso Although stearyl (meth) acrylate, n-lauryl (meth) acrylate, etc. are mentioned, this invention is not limited only to this illustration. These (meth) acrylic acid esters may be used alone or in combination of two or more. Among these (meth) acrylic acid alkyl esters, acrylic acid alkyl esters having 1 to 18 carbon atoms of the alkyl ester are preferred, and n-butyl acrylate, n-octyl acrylate, isooctyl acrylate and 2-ethylhexyl acrylate are preferred. More preferred are n-butyl acrylate and 2-ethylhexyl acrylate.

  In the present specification, “(meth) acrylate” means “acrylate” or “methacrylate”.

  The monomer component may contain a monomer other than the (meth) acrylic acid alkyl ester as long as the object of the present invention is not impaired. As monomers other than (meth) acrylic acid alkyl ester, for example, a monomer having a carboxyl group, a monomer having a hydroxyl group, an acidic phosphate ester monomer, a monomer having an epoxy group, nitrogen Monomers having atoms, monomers having two or more polymerizable double bonds, aromatic monomers, monomers having halogen atoms, vinyl ester monomers, vinyl ether monomers, etc. However, the present invention is not limited to such examples. These monomers may be used alone or in combination of two or more. Among these monomers, a monomer having a carboxyl group and a monomer having a hydroxyl group are preferable.

  Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic anhydride and the like, but the present invention is not limited only to such illustration. These monomers having a carboxyl group may be used alone or in combination of two or more. Among these monomers having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid and maleic anhydride are preferable, and acrylic acid and methacrylic acid are more preferable. Since the monomer having a carboxyl group has a carbon-carbon double bond and a carboxyl group, it is a polyfunctional monomer.

  Examples of the monomer having a hydroxyl group include 2 to 4 carbon atoms of a hydroxyalkyl group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate. However, the present invention is not limited to such examples. These monomers having a hydroxyl group may be used alone or in combination of two or more. Among these monomers having a hydroxyl group, 2-hydroxyethyl acrylate is preferable. The monomer having a hydroxyl group is a polyfunctional monomer because it has a carbon-carbon double bond and a hydroxyl group.

  Examples of acidic phosphate ester monomers include 2-acryloyloxyethyl acid phosphate and 2-methacryloyloxyethyl acid phosphate, but the present invention is not limited to such examples. These acidic phosphate ester monomers may be used alone or in combination of two or more.

  Examples of the monomer having an epoxy group include (meth) acrylic acid esters having an epoxy group such as glycidyl acrylate and glycidyl methacrylate, but the present invention is not limited to such examples. These monomers having an epoxy group may be used alone or in combination of two or more. A monomer having an epoxy group is a polyfunctional monomer because it has a carbon-carbon double bond and an epoxy group.

  In this specification, “(meth) acrylic acid ester” means “acrylic acid ester” or “methacrylic acid ester”, and acrylic acid ester and methacrylic acid ester may be used alone or in combination. Also good.

  Examples of the monomer having a nitrogen atom include N-vinylpyrrolidone, (meth) acrylamide such as acrylamide and methacrylamide, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and imide acrylate. , Having a nitrogen atom such as imide methacrylate, 2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, N-hydroxyethyl (meth) acrylamide (meth) Although acrylate etc. are mentioned, this invention is not limited only to this illustration. These monomers having a nitrogen atom may be used alone or in combination of two or more.

  In the present specification, “(meth) acrylamide” means “acrylamide” or “methacrylamide”, and acrylamide and methacrylamide may be used alone or in combination. Further, “(meth) acrylate” means “acrylate” or “methacrylate”, and acrylate and methacrylate may be used alone or in combination.

  Examples of the monomer having two or more polymerizable double bonds include ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tripropylene glycol diacrylate, and tripropylene glycol. Examples include dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, methyl allyloxymethyl acrylate, etc., but the present invention is not limited to such examples. Absent. These monomers having two or more polymerizable double bonds may be used alone or in combination of two or more. A monomer having two or more polymerizable double bonds is a polyfunctional monomer because it has two or more polymerizable double bonds.

  Examples of the aromatic monomer include styrene compounds such as styrene and α-methylstyrene, but the present invention is not limited to such examples. These aromatic monomers may be used alone or in combination of two or more.

  Examples of the monomer having a halogen atom include vinyl halides such as vinyl chloride, but the present invention is not limited to such examples. Only one type of monomer having a halogen atom may be used, or two or more types may be used in combination.

  Examples of vinyl ester monomers include fatty acid vinyls such as vinyl acetate, but the present invention is not limited to such examples. Only one type of vinyl ester monomer may be used, or two or more types may be used in combination.

  Examples of vinyl ether monomers include butyl vinyl ether and cyclohexyl vinyl ether, but the present invention is not limited to such examples. These vinyl ether monomers may be used alone or in combination of two or more.

  The content of the monomer other than the alkyl acrylate ester in the monomer component is 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass from the viewpoint of improving adhesiveness, cold / heat resistance and wet heat resistance. % Or less, more preferably 20% by mass or less. Further, the lower limit of the content of the monomer other than the alkyl acrylate ester in the monomer component is preferably 0% by mass, more preferably from the viewpoint of improving the adhesiveness, cold resistance and moist heat resistance. It is 3% by mass or more, more preferably 5% by mass or more.

  The adhesive resin preferably has a crosslinkable group in order to be cured with a curing agent. The adhesive resin having a crosslinkable group can be prepared by allowing the monomer component to contain the polyfunctional monomer.

  Among the polyfunctional monomers, from the viewpoint of obtaining a heat dissipation sheet that is comprehensively excellent in adhesiveness, cold resistance, and moist heat resistance, for example, a monomer having a carboxyl group such as (meth) acrylic acid, 2-hydroxy A monomer having a hydroxyl group such as ethyl acrylate and a monomer having two or more polymerizable double bonds are preferred, and a monomer having a carboxyl group and a monomer having a hydroxyl group are more preferred.

  The content of the polyfunctional monomer in the monomer component cannot be determined unconditionally because it varies depending on the type of the polyfunctional monomer, etc., but usually from the viewpoint of sufficiently curing the adhesive resin, Preferably it is 0.1% by mass or more, more preferably 0.2% by mass or more, and further preferably 0.3% by mass or more, and preferably 10% by mass from the viewpoint of improving adhesiveness, cold / heat resistance, and moist heat resistance. Hereinafter, it is more preferably 5% by mass or less, further preferably 3% by mass or less, and still more preferably 1% by mass or less.

  When polymerizing the monomer component, a chain transfer agent may be used as necessary from the viewpoint of suppressing an increase in molecular weight distribution and gelation. Examples of the chain transfer agent include mercaptocarboxylic acids such as mercaptoacetic acid and 3-mercaptopropionic acid; methyl mercaptoacetate, methyl 3-mercaptopropionate, 2-ethylhexyl 3-mercaptopropionate, and n-octyl 3-mercaptopropionate. , Methoxybutyl 3-mercaptopropionate, stearyl 3-mercaptopropionate, trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), dipentaerythritol hexakis (3-mercapto Mercaptocarboxylic esters such as propionate); alkyl such as ethyl mercaptan, tert-butyl mercaptan, n-dodecyl mercaptan, 1,2-dimercaptoethane Llucaptans; mercaptoalcohols such as 2-mercaptoethanol and 4-mercapto-1-butanol; aromatic mercaptans such as benzenethiol, m-toluenethiol, p-toluenethiol and 2-naphthalenethiol; tris [(3- Mercaptopropionyloxy) ethyl] isocyanurate; mercaptoisocyanurates; dihydroxys such as 2-hydroxyethyl disulfide and tetraethylthiuram disulfide; dithiocarbamates such as benzyldiethyldithiocarbamate; dimers such as α-methylstyrene dimer; Examples include halogenated alkyls such as carbon tetrabromide, but the present invention is not limited to such examples. These chain transfer agents may be used alone or in combination of two or more. Among these chain transfer agents, mercaptocarboxylic acids, mercaptocarboxylic acid esters, alkyl mercaptans are obtained because they are easily available, have excellent anti-crosslinking properties, and have a low degree of decrease in polymerization rate. Compounds having a mercapto group such as mercaptoalcohols, aromatic mercaptans and mercaptoisocyanurates are preferred.

  The amount of the chain transfer agent may be appropriately set according to the composition of the monomer component, the polymerization conditions such as the polymerization temperature, the molecular weight of the target polymer, etc., and is not particularly limited, but the weight average molecular weight is several thousand to When obtaining tens of thousands of polymers, the amount is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass per 100 parts by mass of the monomer component.

  Examples of the method for polymerizing the monomer component include a bulk polymerization method, a solution polymerization method, a dispersion polymerization method, a suspension polymerization method, and an emulsion polymerization method, but the present invention is limited to such examples. It is not a thing.

  Bulk polymerization can be performed, for example, by irradiation with energy rays such as ultraviolet rays, electron beams, or radiation, or heating. When bulk polymerization of monomer components is performed by irradiation with energy rays, for example, the monomer components are irradiated by irradiation with energy rays in an inert gas atmosphere such as nitrogen gas or in an atmosphere where air is shut off. It is preferable to polymerize the monomer component.

  When polymerizing the monomer component by the bulk polymerization method, a photopolymerization initiator can be used. Examples of the photopolymerization initiator include an acetophenone polymerization initiator, a benzoin ether polymerization initiator, a benzyl ketal polymerization initiator, an acyl phosphine oxide polymerization initiator, a benzoin polymerization initiator, and a benzophenone polymerization initiator. However, the present invention is not limited to such examples. These photopolymerization initiators may be used alone or in combination of two or more. The amount of the photopolymerization initiator may be appropriately set according to the desired physical properties of the polymer to be obtained, but is usually preferably 0.01 to 50 parts by mass, more preferably 100 parts by mass of the monomer component. Is 0.03 to 20 parts by mass.

  When the monomer component is polymerized by the solution polymerization method, examples of the solvent include aromatic solvents such as benzene, toluene and xylene; alcohol solvents such as isopropyl alcohol and n-butyl alcohol; propylene glycol methyl ether and dipropylene. Ether solvents such as glycol methyl ether, ethyl cellosolve, butyl cellosolve; ester solvents such as ethyl acetate, butyl acetate, cellosolve; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol; amides such as dimethylformamide Although organic solvents, such as a system solvent, are mentioned, this invention is not limited only to this illustration. These solvents may be used alone or in combination of two or more. The amount of the solvent may be appropriately determined in consideration of the polymerization conditions, the composition of the monomer components, the concentration of the resulting polymer, and the like.

  When the monomer component is polymerized by a solution polymerization method, a polymerization initiator can be used. Examples of the polymerization initiator include azoisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), tert-butylperoxy 2-ethylhexanoate, 2,2′-azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, and the like, but the present invention is not limited to such examples. Absent. These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator may be appropriately set according to the desired physical properties of the polymer to be obtained, but is usually preferably 0.001 to 20 parts by mass, more preferably 100 parts by mass of the monomer component. 0.005 to 10 parts by mass.

  The polymerization conditions for polymerizing the monomer components may be set as appropriate according to the polymerization method, and are not particularly limited. The polymerization temperature is preferably room temperature to 200 ° C, more preferably 40 to 140 ° C. Moreover, it is preferable that the atmosphere at the time of polymerizing a monomer component is inert gas, such as nitrogen gas and argon gas. What is necessary is just to set reaction time suitably so that the polymerization reaction of a monomer component may be completed.

  By polymerizing the monomer components as described above, a (meth) acrylic adhesive resin is obtained.

The weight average molecular weight of the (meth) acrylic adhesive resin is preferably 100,000 or more, more preferably 150,000 or more, from the viewpoint of improving the adhesiveness of the heat-dissipating sheet, cold and heat resistance, and dispersion stability of the inorganic filler. More preferably, it is 200,000 or more. The upper limit of the weight average molecular weight of the (meth) acrylic adhesive resin is not particularly limited, but is preferably 1,500,000 or less from the viewpoint of improving the adhesiveness, cold heat resistance and moist heat resistance of the heat dissipation sheet and the dispersion stability of the inorganic filler. More preferably, it is 1,200,000 or less, More preferably, it is 1,000,000 or less, More preferably, it is 900,000 or less.

  In addition, in this specification, the weight average molecular weight of (meth) acrylic-type adhesive resin is a Tosoh Co., Ltd. product number: HLC-8220GPC, as a measuring device of a gel permeation chromatography (GPC), separation column: Tosoh Co., Ltd., product number: TSKgel Super HZM-M is used, which means a conversion value by standard polystyrene [manufactured by Tosoh Co., Ltd.].

  The glass transition temperature of the (meth) acrylic adhesive resin can be easily adjusted by appropriately adjusting the type and amount of the monomer used in preparing the (meth) acrylic adhesive resin.

  The glass transition temperature (Tg) of the (meth) acrylic adhesive resin is preferably −65 ° C. or higher, more preferably −63 ° C. or higher, more preferably from the viewpoint of improving the adhesiveness, cold / heat resistance and moist heat resistance of the heat dissipation sheet. Preferably, it is −62 ° C. or higher, and preferably from −20 ° C. or lower, more preferably −30 ° C. or lower, and even more preferably −40 ° C. or lower, from the viewpoint of improving the adhesiveness, cold heat resistance and wet heat resistance of the heat radiation sheet. .

In the present specification, the glass transition temperature of the (meth) acrylic adhesive resin is the glass transition temperature of the homopolymer of the monomer used in the monomer component used as a raw material for the (meth) acrylic adhesive resin. Use the formula:
1 / Tg = Σ (Wm / Tgm) / 100
[Wm represents the content (% by mass) of monomer m in the monomer component constituting the polymer, and Tgm represents the glass transition temperature (absolute temperature: K) of the homopolymer of monomer m]
The temperature calculated | required based on the Formula of Fox (Fox) represented by these.

  If the glass transition temperature (Tg) of the main homopolymer is indicated, for example, the glass transition temperature (Tg) of the homopolymer of n-butyl acrylate is −54 ° C., the glass transition temperature of the homopolymer of 2-ethylhexyl acrylate ( Tg) is -70 ° C., N-vinylpyrrolidone homopolymer glass transition temperature (Tg) is 180 ° C., acrylic acid homopolymer glass transition temperature (Tg) is 106 ° C., and allyloxymethyl acrylate homopolymer. The glass transition temperature (Tg) of the homopolymer of 2-hydroxyethyl acrylate is -15 ° C., the glass transition temperature (Tg) of the homopolymer of vinyl acetate is 32 ° C. The glass transition temperature (Tg) of the homopolymer is 130 ° C., and the homopolymer glass of methyl acrylate The transition temperature (Tg) is 8 ° C, the glass transition temperature (Tg) of the homopolymer of ethyl acrylate is -22 ° C, the glass transition temperature (Tg) of the homopolymer of 2-hydroxyethyl methacrylate is 55 ° C, 4-hydroxybutyl acrylate The homopolymer glass transition temperature (Tg) is -70 ° C, the methyl methacrylate homopolymer glass transition temperature (Tg) is 105 ° C, the acrylonitrile homopolymer glass transition temperature (Tg) is 125 ° C, and the styrene homopolymer. Has a glass transition temperature (Tg) of 100 ° C.

  In the present specification, the glass transition temperature of the (meth) acrylic adhesive resin means a glass transition temperature obtained based on the above formula unless otherwise specified. For monomers with unknown glass transition temperature such as special monomers and polyfunctional monomers, the total amount of monomers with unknown glass transition temperature in the monomer component is 10% by mass. In the following cases, the glass transition temperature is determined using only monomers whose glass transition temperature is known. When the total amount of monomers with unknown glass transition temperatures in the monomer component exceeds 10% by mass, the glass transition temperature of the (meth) acrylic adhesive resin is determined by differential scanning calorimetry (DSC), differential It is determined by calorimetric analysis (DTA), thermomechanical analysis (TMA) or the like.

  Examples of the differential scanning calorie measuring apparatus used in the differential scanning calorimetry (DSC) include Seiko Instruments Inc., product number: DSC220C. Further, when measuring the differential scanning calorific value, a method of drawing a differential scanning calorific value (DSC) curve, a method of obtaining a first derivative curve from the differential scanning calorific value (DSC) curve, a method of performing a smoothing process, and a method of obtaining a target peak temperature There is no particular limitation. For example, when the measurement device is used, the drawing may be performed from data obtained by using the measurement device. At that time, analysis software capable of performing mathematical processing can be used. Examples of the analysis software include analysis software [manufactured by Seiko Instruments Inc., product number: EXSTAR6000], but the present invention is not limited to such examples. In addition, the peak temperature obtained in this way may include an error due to plotting of about 5 ° C. up and down.

  In consideration of the glass transition temperature of the (meth) acrylic adhesive resin, the composition of the monomer component used as a raw material for the (meth) acrylic adhesive resin can be determined.

  Examples of the inorganic filler include plate-like inorganic particles and spherical inorganic particles. The plate-like inorganic particles and the spherical inorganic particles may be used alone or in combination, but from the viewpoint of further improving the thermal conductivity and further improving the cold and wet heat resistance, the plate-like inorganic particles And spherical inorganic particles are preferably used in combination.

  Examples of the plate-like inorganic particles include alkali metals such as sodium and potassium, alkaline earth metals such as magnesium and calcium, typical metals such as graphite, aluminum, zinc and tin, iron, nickel, copper, manganese, silver and platinum Plate-like metal particles made of transition metals such as alumina; silica, titania, zirconia, magnesia, yttria, zinc oxide, iron oxide, silicon nitride, titanium nitride, boron nitride, silicon carbide, light calcium carbonate, heavy Calcium carbonate, aluminum sulfate, aluminum hydroxide, potassium titanate, talc, kaolin clay, kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amicite, bentonite, asbestos, zeolite, calcium silicate, ke Magnesium acid, diatomaceous earth, but such an inorganic material plated mineral particles such as silica sand and the like, and the present invention is not limited only to those exemplified. These plate-like inorganic particles may be used alone or in combination of two or more. Among the plate-like inorganic particles, from the viewpoint of improving thermal conductivity, plate-like inorganic particles made of aluminum, silver, copper or an alloy thereof, plate-like inorganic particles made of boron nitride, plate-like inorganic particles made of graphite, Plate-like inorganic particles made of alumina, talc and mica are preferable, plate-like inorganic particles made of aluminum, silver, copper or their alloys, plate-like inorganic particles made of boron nitride, plate-like inorganic particles made of graphite and alumina Plate-like inorganic particles are more preferred, and plate-like inorganic particles made of aluminum, silver, copper or their alloys, plate-like inorganic particles made of boron nitride, and plate-like inorganic particles made of graphite are more preferred. Each of the plate-like inorganic particles may be used alone or in combination of two or more.

  If necessary, the plate-like inorganic particles may be subjected to a surface treatment. Surface treatment includes, for example, silane coupling treatment, titanate treatment, oxidation treatment, resin coating treatment, energy ray irradiation treatment, electrochemical treatment, and the like, saturated fatty acids such as stearic acid, oleic acid, linoleic acid and the like. Although the process etc. which adsorb | suck a saturated fatty acid to plate-like inorganic particle | grains are mentioned, this invention is not limited only to this illustration. Among these surface treatments, the plate-like inorganic particles subjected to the resin coating treatment are preferable because they are excellent in insulation.

  Examples of the resin used for the plate-like inorganic particles subjected to the resin coating treatment, that is, the particles coated with the resin include acrylic resins, but the present invention is not limited to such examples. Absent. Among the acrylic resins, for example, an acrylic resin obtained by polymerizing a monomer component mainly composed of an acrylate ester is preferable, and trimethylolpropane triacrylate, acrylic acid, epoxidized polybutadiene, and divinylbenzene are used. A resin obtained by polymerizing the monomer component to be contained is more preferable.

  The coating amount of the resin in the plate-like inorganic particles coated with the resin is preferably 1 part by mass or more per 100 parts by mass of the plate-like inorganic particles, from the viewpoint of improving the electrical insulation properties, especially from the viewpoint of particularly increasing the dielectric breakdown voltage. More preferably, it is 3 parts by mass or more, more preferably 5 parts by mass or more. From the viewpoint of improving thermal conductivity, it is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less. It is.

  The aspect ratio of the plate-like inorganic particles is preferably 1 or more, more preferably 10 or more, still more preferably 30 or more, from the viewpoint of improving thermal conductivity, adhesiveness, cold / heat resistance, and moist heat resistance. From the viewpoint of suppressing thickening with time when the plate-like inorganic particles are mixed, it is preferably 500 or less, more preferably 200 or less, and still more preferably 100 or less.

The aspect ratio of the plate-like inorganic particles is a value obtained by dividing the maximum length in the plane direction of the plate-like inorganic particles by the maximum thickness of the plate-like inorganic particles. In other words, the aspect ratio of the plate-like inorganic particles is expressed by the formula:
[Aspect ratio of plate-like inorganic particles]
= [Maximum length of plate-like inorganic particles in the plane direction] / [Maximum thickness of plate-like inorganic particles]
Based on.

  The maximum length and the maximum thickness in the plane direction of the plate-like inorganic particles are determined by directly observing the plate-like inorganic particles with a scanning electron microscope or the like, and for each arbitrarily selected plate-like inorganic particle, the maximum length and the maximum thickness. The thickness can be measured and obtained as an average value in the measured number. The number of plate-like inorganic particles to be measured is not particularly limited, but is preferably about 10 to 20 from the viewpoint of improving accuracy and convenience of measurement. Note that the maximum length and the maximum thickness of the plate-like inorganic particles contained in the heat dissipation sheet are determined by measuring the plate-like inorganic particles separated by dissolving the heat dissipation sheet with a solvent such as an organic solvent. Can do.

  In the present specification, the length and thickness in the plane direction of the plate-like inorganic particles mean the maximum length and the maximum thickness in the plane direction of one plate-like inorganic particle for convenience.

  The thickness of the plate-like inorganic particles is preferably 0.01 μm or more, more preferably 0.05 μm or more, and further preferably 0.1 μm or more from the viewpoint of improving thermal conductivity. From the viewpoint of suppressing thickening with time when the particles are mixed, it is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less.

  The length in the plane direction of the plate-like inorganic particles is preferably 0.1 μm or more, more preferably 0.2 μm or more from the viewpoint of improving thermal conductivity, and the adhesive resin and the plate-like inorganic particles are mixed. From the viewpoint of suppressing thickening with time, it is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less.

  Examples of the spherical inorganic particles include spherical inorganic particles made of a metal oxide such as silica, alumina, magnesium oxide, zinc oxide and titanium oxide; spherical inorganic particles made of a metal hydroxide such as aluminum hydroxide and magnesium hydroxide; Spherical inorganic particles made of metal nitride such as boron nitride, aluminum nitride, silicon nitride, silicon carbide; spherical inorganic particles made of metal carbide such as silicon carbide; spherical inorganic particles made of inorganic powder such as carbon black and graphite; sodium Metal particles composed of alkali metals such as potassium, alkaline earth metals such as magnesium and calcium, typical metals such as aluminum, zinc and tin, and transition metals such as iron, nickel, copper, manganese, silver and platinum However, the present invention is limited to only such examples. Not to. These spherical inorganic particles may be used alone or in combination of two or more. Among these spherical inorganic particles, alumina, magnesium oxide, aluminum hydroxide, magnesium hydroxide, aluminum nitride and silicon carbide are preferable.

  The average particle diameter of the spherical inorganic particles is preferably 0.01 to 20 μm, more preferably 0.01 to 10 μm, from the viewpoint of improving the thermal conductivity of the heat dissipation sheet. The maximum particle size of the spherical inorganic particles is preferably 0.01 to 130 μm, more preferably 0.01 to 110 μm, and still more preferably 0.01 to 100 μm, from the viewpoint of improving thermal conductivity and adhesiveness. . The average particle size and the maximum particle size of the spherical inorganic particles are values measured using a laser diffraction / scattering particle size distribution measuring device [manufactured by Horiba, Ltd., product number: LA-920].

  The ratio of the plate-like inorganic particles to the spherical inorganic particles [plate-like inorganic particles / spherical inorganic particles (mass ratio)] is preferably 1/30 or more from the viewpoint of improving the thermal conductivity and adhesiveness of the heat-dissipating sheet. Preferably it is 1/25 or more, and from the viewpoint of improving the thermal conductivity and adhesiveness of the heat dissipation sheet, it is preferably 1/3 or less, more preferably 1/4 or less.

  The amount of the inorganic filler per 100 parts by mass of the non-volatile content of the adhesive resin is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, and further preferably from the viewpoint of improving the thermal conductivity and adhesiveness of the heat dissipation sheet. 200 parts by mass or more, and preferably 900 parts by mass or less, more preferably 800 parts by mass or less, and still more preferably 850 parts by mass from the viewpoint of improving the dispersion stability of the inorganic filler and the thermal conductivity and adhesiveness of the heat dissipation sheet. Hereinafter, it is still more preferably 800 parts by mass or less, particularly preferably 750 parts by mass or less.

  As the curing agent, a compound having two or more functional groups capable of reacting with the crosslinkable group of the adhesive resin in one molecule can be used.

  Examples of the curing agent include a polyisocyanate curing agent, a polyfunctional epoxy curing agent, a silicone curing agent, and the like, but the present invention is not limited to such examples.

  Examples of the polyisocyanate curing agent include aromatic polyisocyanates such as xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated products of the above aromatic polyisocyanates. Aliphatic or cycloaliphatic polyisocyanates, dimers or trimers of these polyisocyanates, adducts composed of these polyisocyanates and polyols such as trimethylolpropane, and the like. It is not limited to illustration only. These polyisocyanate curing agents may be used alone or in combination of two or more.

  Polyisocyanates are, for example, “Coronate L”, “Coronate L-55E”, “Coronate HX”, “Coronate HL”, “Coronate HL-S”, “Coronate 2234”, “Aquanate 200”, “Aquanate 210”. [The above is made by Nippon Polyurethane Industry Co., Ltd., “Coronate” and “Aquanate” are registered trademarks], “Desmodule N3400” (manufactured by Sumitomo Bayer Urethane Co., Ltd. (currently Bayer AG), “Death” "Module" is a registered trademark], "Duranate D-201", "Duranate TSE-100", "Duranate TSS-100", "Duranate 24A-100", "Duranate E-405-80T" [above, Asahi Kasei Chemicals Corporation "Duranate" is a registered trademark], "Takenate D-110N" "Nate D-120N", "Takenate M-631N", "MTERT-Olestar NP1200" (Mitsui Chemicals Polyurethane Co., Ltd., "Takenate" and "Olestar" are registered trademarks) It can be obtained. These polyisocyanates may be used alone or in combination of two or more.

  Examples of the polyfunctional epoxy curing agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A type epoxy resin, N, N, N ′, N′-tetra. Examples include glycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N-diglycidylaniline, N, N-diglycidyltoluidine, etc. It is not limited to illustration only. These polyfunctional epoxy curing agents may be used alone or in combination of two or more.

  Examples of the silicone-based curing agent include Shin-Etsu Chemical Co., Ltd., product number: X-92-122, but the present invention is not limited to such examples. Only one type of silicone curing agent may be used, or two or more types may be used in combination.

  Among the curing agents, polyisocyanate dimers, polyisocyanate trimers, polyisocyanate bifunctional prepolymers and polyisocyanate adducts are preferred. Hexamethylene diisocyanate dimer, hexamethylene diisocyanate isocyanate. More preferred are adduct bodies of tolylene diisocyanate such as nurate bodies (trimers) and adduct bodies of tolylene diisocyanate and trimethylolpropane. Examples of the isocyanurate of hexamethylene diisocyanate include Asahi Kasei Chemicals Corporation, trade name: Duranate (registered trademark) TSE-100, trade name: Duranate (registered trademark) TSS-100, and the like. Is not limited to such examples.

  The amount of the curing agent is usually preferably 0.01 to 1 equivalent, more preferably 0.05 to 0.8 equivalent, when the total amount of crosslinkable groups (functional groups) of the adhesive resin is 1 equivalent. It is. In addition, the amount of the curing agent (nonvolatile content) per 100 parts by mass of the nonvolatile content of the adhesive resin is preferably 0.3 parts by mass or more, more preferably 0.5 masses, from the viewpoint of suppressing cohesive failure of the heat dissipation sheet. From the viewpoint of improving adhesiveness, cold heat resistance and wet heat resistance, it is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less.

  Moreover, you may use a hardening accelerator in a suitable quantity for a thermal radiation material. Examples of the curing accelerator include dibutyltin dilaurate, tin octoate, dibutyltin di (2-ethylhexanoate), 2-ethylhexanoate lead, 2-ethylhexyl titanate, 2-ethylhexanoate iron, Examples include 2-ethylhexanoate cobalt, zinc naphthenate, cobalt naphthenate, tin octoate, bismuth octoate, tetra-n-butyltin, diisopropoxytitanium bis (ethylacetoacetate), and zirconium tetraacetylacetonate. The present invention is not limited to such examples. These curing accelerators may be used alone or in combination of two or more.

  The heat dissipating material preferably contains an aliphatic carboxylic acid ester from the viewpoint of improving adhesiveness, cold resistance, and wet heat resistance. As the aliphatic carboxylic acid ester, an esterified product of an aliphatic carboxylic acid having 2 to 20 carbon atoms is preferable from the viewpoint of improving adhesiveness, heat resistance and heat resistance. Moreover, it is preferable that the ester group of aliphatic carboxylic acid ester is a C2-C20 alkyl group from a viewpoint of improving adhesiveness, cold-heat resistance, and heat-and-moisture resistance. Examples of the aliphatic carboxylic acid ester include monovalent aliphatic carboxylic acid esters and polyvalent aliphatic carboxylic acid esters, and any of them can be used in the present invention. The monovalent aliphatic carboxylic acid ester and the polyvalent aliphatic carboxylic acid ester may be used alone or in combination.

  Examples of the monovalent aliphatic carboxylic acid ester include alkyls of 2 to 20 carbon atoms of monovalent aliphatic carboxylic acids having 2 to 20 carbon atoms such as myristic acid alkyl ester, ricinoleic acid alkyl ester, and oleic acid alkyl ester. Although ester etc. are mentioned, this invention is not limited only to this illustration. These monovalent aliphatic carboxylic acid alkyl esters may be used alone or in combination of two or more. Among these monovalent aliphatic carboxylic acid alkyl esters, myristic acid alkyl esters are preferable, and isopropyl myristate is more preferable.

  Examples of the polyvalent aliphatic carboxylic acid ester include divalent aliphatics having 2 to 20 carbon atoms such as adipic acid alkyl ester, sebacic acid alkyl ester, azelaic acid alkyl ester, maleic acid alkyl ester, and itaconic acid alkyl ester. Although C2-C20 alkylester of carboxylic acid etc. are mentioned, this invention is not limited only to this illustration. These polyvalent aliphatic carboxylic acid alkyl esters may be used alone or in combination of two or more. Among these polyvalent aliphatic carboxylic acid alkyl esters, diisononyl adipate and diisodecyl adipate are more preferable.

  The amount of the aliphatic carboxylic acid ester is preferably 1.2 or more, more preferably 1.5 or more, from the viewpoint of improving adhesiveness, cold / heat resistance and moist heat resistance per 100 parts by mass of the nonvolatile content of the adhesive resin. From the viewpoint of maintaining the shape of the heat dissipation sheet, it is preferably 140 or less, more preferably 130 or less.

  In addition, the heat dissipation material, as long as it does not hinder the purpose of the present invention, for example, a dispersant, a tackifier, an antioxidant, a flame retardant, a flame retardant aid, an anti-settling agent, a thickener, Additives such as thixotropy-imparting agents, surfactants, antifoaming agents, antistatic agents, surface treatment agents, anti-aging agents, ultraviolet absorbers, and ultraviolet stabilizers may be contained in appropriate amounts.

  The nonvolatile content in the heat dissipation material is preferably 20% by mass or more, more preferably 30% by mass or more from the viewpoint of improving productivity, and preferably 80% by mass or less, more preferably from the viewpoint of improving coating properties. Is 70% by mass or less. The nonvolatile content in the heat dissipation material can be adjusted by adjusting the amount of the solvent, the amount of the additive, and the like contained in the heat dissipation material. The solvent may be the same as the organic solvent used for the adhesive resin solution.

  The heat dissipation material can be easily prepared by mixing an adhesive resin, an inorganic filler, a curing agent, and other components as necessary. At this time, it is preferable to use an adhesive resin solution in which an adhesive resin is dissolved in an organic solvent from the viewpoint of preparing a heat dissipation material in which an inorganic filler or the like is uniformly dispersed.

  The organic solvent used for the adhesive resin solution is not particularly limited as long as it dissolves the adhesive resin. Examples of the organic solvent include gasoline, coal tar naphtha, petroleum ether, petroleum benzine, turonic acid, mineral spirit, and the like in addition to the organic solvent used when the monomer component is polymerized by a solution polymerization method. However, the present invention is not limited to such examples. The concentration of the nonvolatile content in the adhesive resin solution is not particularly limited, but is usually about 10 to 70% by mass.

  The heat radiating sheet of the present invention may be composed only of the heat radiating material, or the adhesive layer made of the heat radiating material may be formed on one surface or both surfaces of the base material, and is made of the heat radiating material. It may have an adhesive layer and a release liner, or it has a base material and a release liner, and an adhesive layer made of the heat dissipation material is formed between the base material and the release liner. Also good.

  Examples of the method for forming the adhesive layer (heat radiating material layer) from the heat radiating material include a method of applying the heat radiating material to the surface of the release liner or the base material, but the present invention is limited only to such examples. It is not a thing.

  As a method of applying the heat dissipation material to the release liner or the substrate, for example, a coating method using a knife coater, slot die coater, lip coater, roll coater, flow coater, spray coater, bar coater, comma coater, doctor blade, etc. Examples of the coating method include dipping and the like, but the present invention is not limited to such examples. When applying the heat-dissipating material to the substrate, the heat-dissipating material may be applied directly to the substrate, or after applying the heat-dissipating material to a release liner or the like, the coated material may be transferred onto the substrate. Thus, after apply | coating a heat radiating material to a base material, it can dry and can obtain the heat radiating sheet in which the adhesion layer (heat radiating material layer) was formed on the base material.

  Examples of the release liner include polyolefin resin films such as polyethylene and polypropylene, polyester resin films such as polyethylene terephthalate, polystyrene resin films, glassine paper, and the like, but the present invention is limited only to such examples. It is not a thing. In addition, when using a resin film as a peeling liner, resin processing, such as a silicone resin and a fluororesin, may be given.

  In general, the size and shape of the release liner are preferably adjusted so as to have a size and shape corresponding to the adhesive layer (heat dissipation material layer) formed on the heat dissipation sheet.

  Examples of the base material include paper such as fine paper, kraft paper, crepe paper, and glassine paper, resin base materials, textile products such as woven fabrics, non-woven fabrics, and fabrics, and conductive base materials. The invention is not limited to such examples. Among the base materials, since the heat dissipation sheet of the present invention and, for example, a wiring board, a heat sink, and a member such as a housing that require heat dissipation can be suitably used, a resin base material, Nonwoven fabrics and conductive substrates are preferred.

  Examples of the resin used for the resin substrate include polyolefin resins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polystyrene, polyvinyl chloride, cellophane, acrylic resin, polyimide, polyphenylene sulfide, and polyamide. However, the present invention is not limited to such examples. Examples of the resin substrate include a resin film and a sheet. The thickness of the resin film cannot be determined unconditionally because it varies depending on the use of the heat dissipation sheet of the present invention, but is usually about 1 to 40 μm, and preferably 1 μm or more from the viewpoint of improving electrical insulation. More preferably, it is 2 μm or more, more preferably 3 μm or more. From the viewpoint of improving thermal conductivity, it is preferably 40 μm or less, more preferably 30 μm or less, even more preferably 20 μm or less, even more preferably 10 μm or less, even more. Preferably it is 5 micrometers or less.

Examples of the nonwoven fabric include a spunbond nonwoven fabric, a melt blown nonwoven fabric, and a needle punched nonwoven fabric. However, the present invention is not limited to such examples. Of these nonwoven fabrics, spunbond nonwoven fabrics are preferred. Examples of the fibers constituting the nonwoven fabric include polyolefin resins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, resins such as polystyrene, polyvinyl chloride, cellophane, acrylic resins, polyimide, polyphenylene sulfide, and polyamide. Synthetic fibers, regenerated fibers such as rayon and cupra, semisynthetic fibers such as acetate, and the like. However, the present invention is not limited to such examples. Although the thickness and basic weight of a nonwoven fabric are arbitrary, as an example, thickness is 3-50 micrometers and basic weight is 5-100 g / m < ² >. The thickness of the nonwoven fabric is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 7 μm or more from the viewpoint of improving electrical insulation, and preferably 50 μm or less, more preferably from the viewpoint of improving thermal conductivity. Is 45 μm or less, more preferably 40 μm or less. The basis weight of the nonwoven fabric is preferably 5 g / m ² or more, more preferably 10 g / m ² or more, and further preferably 15 g / m ² or more from the viewpoint of improving thermal conductivity. From the viewpoint of improving conductivity, it is preferably 100 g / m ² or less, more preferably 80 g / m ² or less, and still more preferably 60 g / m ² or less.

  Examples of conductive base materials include titanium foil, stainless steel foil, nickel foil, nickel-chromium alloy foil, copper foil, beryllium foil, aluminum foil, tin foil, lead foil, zinc foil, iron foil, molybdenum foil, and zirconium foil. , Gold foil, silver foil, platinum foil, metal foil such as palladium foil, graphite sheet, and the like can be mentioned, but the present invention is not limited to such examples. The thickness of the conductive substrate is arbitrary, but is usually about 1 to 40 μm. From the viewpoint of improving thermal conductivity, it is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 3 μm or more. From the viewpoint of improving the flexibility of the heat dissipation sheet, it is preferably 40 μm or less, more preferably 30 μm or less, still more preferably 20 μm or less, still more preferably 10 μm or less, and even more preferably 5 μm or less.

  When using the base material for the heat dissipation sheet of the present invention, the adhesive layer may be formed by directly applying the heat dissipation material on the base material. After the heat dissipation material is applied to the release liner, the adhesive layer formed May be transferred to a substrate. When applying the heat dissipation material to one surface of the substrate, it is preferable to attach a release liner to the surface of the adhesive layer in order to protect the formed adhesive layer. Moreover, when apply | coating a thermal radiation material to both surfaces of a base material, in order to protect the adhesive layer formed, it is preferable to stick a release liner to the surface of the adhesive layer of the both surfaces of the said base material, respectively. In addition, when a base material is not used for the heat-dissipating sheet of the present invention, it is preferable to apply a heat-dissipating material to a release liner and protect the surface of the adhesive layer with another release liner having a different release force from the release liner. .

  The heat dissipation material is applied to a release liner or a substrate and then dried. Examples of the drying method include irradiation with hot air and far infrared rays.

  Thickness of the pressure-sensitive adhesive layer after drying of the heat-radiating sheet of the present invention [when the heat-radiating sheet of the present invention is composed only of the pressure-sensitive adhesive layer, the thickness of the heat-radiating sheet consisting of only the pressure-sensitive adhesive layer (thickness of the release liner) If the heat dissipation sheet of the present invention has a base material, the total thickness of the adhesive layer and the base material (not including the thickness of the release liner)] From the viewpoint of increasing the mechanical strength, it is preferably 1 μm or more, more preferably 5 μm, even more preferably 10 μm or more, still more preferably 30 μm or more, and even more preferably 50 μm or more. From the viewpoint of reducing the thermal resistance of the heat dissipation sheet, Is 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less.

  The total thickness of the heat dissipation sheet of the present invention is obtained by adding the thickness of the release liner and / or the thickness of the base material to the thickness of the heat dissipation sheet not including the release liner and the base material. The total thickness of the heat dissipation sheet is preferably 1 to 600 μm, more preferably 1 to 500 μm, still more preferably 1 to 400 μm, still more preferably 1 to 300 μm, and still more preferably 1 to 600 μm, from the viewpoint of reducing thermal resistance. 250 μm. Moreover, from the viewpoint of following the unevenness of the adherend, the overall thickness of the heat dissipation sheet is preferably 1 to 600 μm, more preferably 30 to 600 μm, and still more preferably 50 to 600 μm.

The thermal resistance of the heat dissipation sheet is a value (m ² · K / W) obtained by dividing the thickness (m) of the heat dissipation material by the thermal conductivity (W / mK), and the smaller the value, The heat dissipation sheet of the present invention is excellent in thermal conductivity.

  The ratio of the maximum particle diameter of the inorganic filler to the thickness of the heat dissipation sheet (maximum particle diameter of the inorganic filler / thickness of the heat dissipation sheet) is preferably 0.01 to 2, more preferably from the viewpoint of improving the adhesiveness. Is 0.01 to 1.5, more preferably 0.03 to 1.

  The heat dissipating sheet of the present invention obtained as described above is generally excellent in heat conductivity, cold heat resistance and wet heat resistance. Therefore, the heat dissipation sheet of the present invention can be suitably used when, for example, a wiring board and a member that requires heat dissipation such as a heat sink and a housing are joined.

  EXAMPLES Next, although this invention is demonstrated further in detail based on an Example, this invention is not limited only to this Example.

Production Example 1
In a reaction vessel equipped with a cooling pipe, a nitrogen gas introduction pipe, a thermometer, a dropping funnel and a stirrer, 100 parts of ethyl acetate (mass part, the same shall apply hereinafter), 70.0 parts of n-butyl acrylate, 2-ethylhexyl acrylate 22. 7 parts, 2.0 parts of acrylic acid, 0.3 part of 2-hydroxyethyl acrylate and 5.0 parts of vinyl acetate were added, and then 0.1 part of azoisobutyronitrile was added. By reacting at 5 ° C. for 5 hours, a solution of adhesive resin A was obtained (nonvolatile content: 50% by mass). The obtained adhesive resin A had a weight average molecular weight of 600,000 and a glass transition temperature of −52.9 ° C.

Production Example 2
In a reaction vessel equipped with a cooling pipe, a nitrogen gas introduction pipe, a thermometer, a dropping funnel and a stirrer, 100 parts of ethyl acetate, 70.0 parts of n-butyl acrylate, 21.7 parts of 2-ethylhexyl acrylate, 2-hydroxyethyl After adding 0.3 part of acrylate, 3.0 part of N-vinylpyrrolidone and 5.0 part of vinyl acetate, 0.1 part of azoisobutyronitrile is added and reacted at 80 ° C. for 5 hours in a nitrogen gas atmosphere. As a result, a solution of the adhesive resin B was obtained (nonvolatile content: 50% by mass). The obtained adhesive resin B had a weight average molecular weight of 600,000 and a glass transition temperature of −51.3 ° C.

Production Example 3
In a reaction vessel equipped with a cooling pipe, a nitrogen gas introduction pipe, a thermometer, a dropping funnel and a stirrer, 100 parts of ethyl acetate, 70.0 parts of n-butyl acrylate, 22.7 parts of 2-ethylhexyl acrylate, 2. acrylic acid. 0 parts, 0.3 parts of 2-hydroxyethyl acrylate and 5.0 parts of vinyl acetate, and then 0.2 parts of azoisobutyronitrile are added and reacted at 80 ° C. for 5 hours in a nitrogen gas atmosphere. Thus, a solution of the adhesive resin C was obtained (nonvolatile content: 50% by mass). The obtained adhesive resin C had a weight average molecular weight of 300,000 and a glass transition temperature of −52.9 ° C.

Production Example 4
In a reaction vessel equipped with a cooling pipe, a nitrogen gas introduction pipe, a thermometer, a dropping funnel and a stirrer, 100 parts of ethyl acetate, 70.0 parts of n-butyl acrylate, 21.7 parts of 2-ethylhexyl acrylate, 2-hydroxyethyl After adding 0.3 part of acrylate, 3.0 part of N-vinylpyrrolidone and 5.0 part of vinyl acetate, 0.2 part of azoisobutyronitrile is added and reacted at 80 ° C. for 5 hours in a nitrogen gas atmosphere. As a result, a solution of the adhesive resin D was obtained (nonvolatile content: 50% by mass). The obtained adhesive resin D had a weight average molecular weight of 300,000 and a glass transition temperature of −51.3 ° C.

Example 1
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin A obtained in Production Example 1 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 40). ) After mixing the adhesive resin A solution, spherical alumina particles, plate-like boron nitride particles and diisononyl adipate so that the amount of diisononyl adipate is 10 parts. Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 200 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 2
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin B obtained in Production Example 2 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 200) ) After mixing the adhesive resin B solution, spherical alumina particles, plate-like boron nitride particles and diisononyl adipate so that the amount of diisononyl adipate is 60 parts. Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin B becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness after drying of about 300 μm was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 3
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin C obtained in Production Example 3 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 40). ) After mixing the adhesive resin C solution, spherical alumina particles, plate-like boron nitride particles and diisononyl adipate so that the amount of diisononyl adipate is 5 parts. Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin C becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 200 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 4
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of nonvolatile content of the adhesive resin D obtained in Production Example 4 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 40). ), And the mixture of the adhesive resin D, spherical alumina particles, plate-like boron nitride particles and diisononyl adipate so that the amount of diisononyl adipate is 5 parts, the non-volatile content is Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin D becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 200 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 5
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of nonvolatile content of the adhesive resin A obtained in Production Example 1 is 300 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 100) ), 25 parts of aluminum hydroxide particles (maximum particle size: 10 μm), 200 parts, and 20 parts of diisononyl adipate, solution of adhesive resin A, spherical alumina particles, plate nitriding After mixing boron particles, aluminum hydroxide particles, and diisononyl adipate, ethyl acetate was added so that the content of non-volatile content was 50% by mass, and the mixture was sufficiently stirred to obtain a mixed solution.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 250 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 6
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of nonvolatile content of the adhesive resin A obtained in Production Example 1 is 500 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 20). ) After mixing the adhesive resin A solution, spherical alumina particles, plate-like boron nitride particles and isopropyl myristate so that the amount of isopropyl myristate is 5 parts. Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 150 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 7
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of nonvolatile content of the adhesive resin B obtained in Production Example 2 is 500 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 40). After mixing the adhesive resin B solution, spherical alumina particles, plate-like boron nitride particles and isopropyl myristate so that the amount of) is 50 parts and the amount of isopropyl myristate is 15 parts, the non-volatile content is Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin B becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 150 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 8
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin A obtained in Production Example 1 is 600 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 10). ) After mixing the adhesive resin A solution, spherical alumina particles, plate-like boron nitride particles and diisodecyl adipate so that the amount of diisodecyl adipate is 15 parts. Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 250 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 9
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of nonvolatile content of the adhesive resin A obtained in Production Example 1 is 600 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 100) ) After mixing the solution of adhesive resin A, spherical alumina particles, plate-like boron nitride particles and diisodecyl adipate so that the amount of diisodecyl adipate is 80 parts. Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness after drying of about 300 μm was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 10
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin A obtained in Production Example 1 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 80 ), The mixture of the adhesive resin A, the spherical alumina particles, the plate-like boron nitride particles and the diisodecyl adipate are mixed so that the amount of diisodecyl adipate is 20 parts. Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat radiation material obtained above is applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS) and dried in an atmosphere at 100 ° C. for 2 minutes, so that the thickness after drying is about 99 μm. A heat-dissipating sheet A having an adhesive layer was obtained. Further, the heat-dissipating material obtained above was applied onto a release liner [manufactured by Toyobo Co., Ltd., product number: E-7006] and dried in an atmosphere at 100 ° C. for 2 minutes, so that the thickness after drying was about A heat dissipation sheet B having a 99 μm adhesive layer was obtained.

  Next, the heat radiating sheet A and the heat radiating sheet B obtained above are respectively transferred to both surfaces of a polyethylene terephthalate film (thickness: 2 μm) and cured at 40 ° C. for 2 days, thereby forming polyethylene as a base material (core material). A heat dissipation sheet having a terephthalate film and having an overall thickness of about 200 μm was obtained. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 11
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin A obtained in Production Example 1 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 80 ), The mixture of the adhesive resin A, the spherical alumina particles, the plate-like boron nitride particles and the diisodecyl adipate are mixed so that the amount of diisodecyl adipate is 20 parts. Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS) and dried in an atmosphere at 100 ° C. for 2 minutes, so that the thickness after drying was about 95 μm. A heat-dissipating sheet A having an adhesive layer was obtained. Further, the heat-dissipating material obtained above was applied onto a release liner [manufactured by Toyobo Co., Ltd., product number: E-7006] and dried in an atmosphere at 100 ° C. for 2 minutes, so that the thickness after drying was about A heat-dissipating sheet B having a 95 μm adhesive layer was obtained.

  Next, the heat-dissipating sheet A and the heat-dissipating sheet B obtained above are respectively transferred to both surfaces of a graphite sheet (thickness: 10 μm) and cured at 40 ° C. for 2 days, whereby a graphite sheet is used as a base material (core material). A heat radiating sheet having a total thickness of about 200 μm was obtained. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 12
The amount of spherical alumina particles (maximum particle size: 10 μm) per 100 parts of nonvolatile content of the adhesive resin A obtained in Production Example 1 is 300 parts, plate-like boron nitride particles (maximum length: 5 μm, aspect ratio: 10). ), The mixture of the adhesive resin A, spherical alumina particles, plate-like boron nitride particles and diisononyl adipate so that the amount of diisononyl adipate is 3 parts, the non-volatile content is Ethyl acetate was added so that it might become 50 mass%, and the mixed solution was obtained by fully stirring.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 50 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling each release liner.

Example 13
A heat radiating sheet was produced in the same manner as in Example 1 except that the spherical alumina particles were not used.

Example 14
A heat radiating sheet was produced in the same manner as in Example 1 except that the plate-like boron nitride particles were not used.

Comparative Example 1
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin A obtained in Production Example 1 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 40). ), 75 parts of the tackifier, [Arakawa Chemical Industries, Ltd., product number: Superester A-18] so that the amount of the adhesive resin A solution, spherical alumina particles, and plate-like nitriding are 20 parts. After mixing the boron particles and the tackifier, ethyl acetate was added so that the nonvolatile content was 50 mass%, and the mixture was sufficiently stirred to obtain a mixed solution.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS), dried in an atmosphere at 60 ° C. for 3 minutes, and then dried in an atmosphere at 110 ° C. for 3 minutes. As a result, an adhesive layer having a thickness of about 200 μm after drying was formed. Thereafter, the surface of the adhesive layer was protected with a polyester release liner [manufactured by Toyobo Co., Ltd., product number: E-7006], and cured at 40 ° C. for 3 days to obtain a heat radiating sheet. This heat radiating sheet was used as a heat radiating sheet having adhesive layers on both sides by peeling the release liner.

Comparative Example 2
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin A obtained in Production Example 1 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 200) ), The mixture of the adhesive resin A solution, spherical alumina particles, and plate-like boron nitride particles were mixed, and then ethyl acetate was added so that the content of nonvolatile content was 50% by mass. By thoroughly stirring, a mixed solution was obtained.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat dissipation material obtained above was applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS) so that the thickness after drying was about 200 μm, and dried in an atmosphere at 100 ° C. for 5 minutes. However, since the shape of the heat radiating sheet could not be maintained, its physical properties could not be measured.

Comparative Example 3
The amount of spherical alumina particles (maximum particle size: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin A obtained in Production Example 1 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 40). ), And the mixture of the adhesive resin A, spherical alumina particles and isopropyl myristate so that the amount of isopropyl myristate is 150 parts, the nonvolatile content is 50% by mass. Ethyl acetate was added to, and the mixture was sufficiently stirred to obtain a mixed solution.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat radiation material obtained above is applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS) and dried in an atmosphere at 100 ° C. for 5 minutes, whereby the thickness of the adhesive layer is about 200 μm. However, since the shape of the heat dissipation sheet could not be maintained, its physical properties could not be measured.

Comparative Example 4
The amount of spherical alumina particles (maximum particle diameter: 90 μm) per 100 parts of the nonvolatile content of the adhesive resin A obtained in Production Example 1 is 525 parts, plate-like boron nitride particles (maximum length: 20 μm, aspect ratio: 100) ), The mixture of the adhesive resin A, the spherical alumina particles and isopropyl myristate so that the amount of isopropyl myristate is 1 part, and then the nonvolatile content is 50% by mass. Ethyl acetate was added to, and the mixture was sufficiently stirred to obtain a mixed solution.

  Next, the amount of the curing agent [manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate, product name: Coronate L-55E] with respect to 100 parts of the active ingredient (nonvolatile content) of the adhesive resin A becomes 2 parts (nonvolatile content). Thus, the heat dissipation material was obtained by mixing the mixed solution and hardener which were obtained above.

  The heat radiation material obtained above is applied onto a release liner (manufactured by Sanei Kaken Co., Ltd., product number: K-80HS) and dried in an atmosphere at 100 ° C. for 5 minutes, whereby the thickness of the adhesive layer is about 200 μm. The heat dissipation sheet was obtained.

Comparative Example 5
The amount of n-butyl acrylate is 10 parts, the amount of 2-ethylhexyl acrylate is 90 parts, the amount of 1,6-hexanediol acrylate is 0.1 part, and the amount of spherical alumina particles (maximum particle size: 90 μm) is 300 parts. N-butyl acrylate, 2-aluminum hydroxide particles (maximum particle size: 10 μm), 700 parts, 15 parts of isopropyl myristate and 0.1 parts of photopolymerization initiator, A heat conductive composition was obtained by mixing ethylhexyl acrylate, 1,6-hexanediol acrylate, spherical alumina particles, spherical aluminum hydroxide particles, isopropyl myristate and a photopolymerization initiator. The obtained heat conductive composition was coated on a polyethylene terephthalate film (release film) treated with a silicone release agent, and polymerized by irradiating with ultraviolet rays at an ultraviolet intensity of 5 mW / cm ² for 10 minutes, thereby causing an adhesive layer. A heat conductive adhesive sheet having a thickness of 200 μm was obtained. Although the weight average molecular weight of the adhesive resin obtained by polymerizing the thermally conductive composition could not be measured, when the glass transition temperature was measured, the glass transition temperature was −68.5 ° C. there were.

  Next, the following physical properties were examined using the heat dissipation sheet obtained in each example or each comparative example. The results are shown in Table 1.

(Thermal conductivity)
The thermal diffusivity of the heat-dissipating sheet was measured using a thermal diffusivity / thermal conductivity measuring device [trade name: ai-phase mobile 1 manufactured by Hitachi High-Technologies Corporation]. The specific heat of the heat radiating sheet was measured using a differential scanning calorimeter [manufactured by Seiko Instruments Inc., product number: DSC220C]. Moreover, the specific gravity of the heat dissipation sheet was determined by cutting the heat dissipation sheet into a size of 50 mm in length and 50 mm in width and measuring the mass of the obtained test piece.

Next, the thermal conductivity (hereinafter also referred to as “initial thermal conductivity”) is expressed by the formula:
[Thermal conductivity (W / mK)] = [thermal diffusivity (m ² / s)] × [specific heat (J / kgK)] × [specific gravity (g / cm ³ )]
The thermal conductivity of the heat dissipation sheet was evaluated based on the following evaluation criteria.
[Evaluation criteria]
30: Thermal conductivity is 3 W / mK or more 20: Thermal conductivity is 1 W / mK or more and less than 3 W / mK 10: Thermal conductivity is 0.5 W / mK or more and less than 1 W / mK 0: Thermal conductivity is 0.5 W / m less than mK

[Adhesiveness]
A heat-dissipating sheet having a length of 50 mm and a width of 25 mm was prepared by peeling off one side of the liner and backing a polyethylene terephthalate film (thickness: 25 μm).

The other release liner of the test piece obtained above was peeled off, and the adhesive surface was attached to an aluminum plate (thickness: 1 mm), and added with a roller having a mass of 2 kg in an atmosphere at a temperature of 23 ° C. and a relative humidity of 65%. After press-bonding and allowing to stand for 24 hours, the test piece is peeled off from the aluminum plate at a peeling rate of 300 mm / min in the direction of 180 °, and the adhesive strength at that time is measured. evaluated.
[Evaluation criteria]
30: Adhesive strength is 1000 mN / 25 mm or more 20: Adhesive strength is 500 mN / 25 mm or more and less than 1000 mN / 25 mm 10: Adhesive force is less than 500 mN / 25 mm

[Cool resistance]
A series of operations of leaving the heat dissipation sheet in an atmosphere of −40 ° C. for 10 minutes and then leaving the heat dissipation sheet in an atmosphere of 120 ° C. for 0 minute is defined as one cycle (about 20 minutes), and the operation is performed for 500 cycles. After that, in the same manner as the “thermal conductivity”, the thermal conductivity of the heat radiating sheet (hereinafter referred to as the thermal conductivity after the cooling test) is obtained by the formula:
[Change rate of thermal conductivity]
= [| Thermal conductivity after the cold test-initial thermal conductivity |] / [initial thermal conductivity] × 100
Based on the above, the rate of change in thermal conductivity was determined, and cold resistance was evaluated based on the following evaluation criteria.
[Evaluation criteria]
30: Change rate of thermal conductivity is less than 20% 20: Change rate of thermal conductivity is 20% or more and less than 30% 10: Change rate of thermal conductivity is 30% or more and less than 40% 0: Change rate of thermal conductivity Is 40% or more, or the thermal conductivity cannot be measured (breakage of the coating film, etc.)

[Moisture and heat resistance]
The heat-dissipating sheet is placed in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90%, and the thermal conductivity (hereinafter referred to as the thermal conductivity after the wet heat test) is obtained after 1000 hours in the same manner as the above “thermal conductivity” :
[Change rate of thermal conductivity]
= [| Thermal conductivity after the wet heat test-the initial thermal conductivity |] / [the initial thermal conductivity] × 100
Based on the above, the rate of change in thermal conductivity was determined, and the resistance to moist heat was evaluated based on the following evaluation criteria.
[Evaluation criteria]
30: Change rate of thermal conductivity is less than 20% 20: Change rate of thermal conductivity is 20% or more and less than 30% 10: Change rate of thermal conductivity is 30% or more and less than 40% 0: Change rate of thermal conductivity Is 40% or more, or the thermal conductivity cannot be measured (breakage of the coating film, etc.)

  Next, each score of the thermal conductivity, adhesiveness, cold resistance, and wet heat resistance of the heat-dissipating sheet obtained in each example or each comparative example was summed. The total score is shown in the column of comprehensive evaluation in Table 1.

  From the results shown in Table 1, the heat dissipation sheet obtained in each comparative example has an overall evaluation of 80 points or less, whereas the heat dissipation sheet obtained in each example has an overall evaluation. Since all are 90 points or more, it turns out that it is excellent in heat conductivity, cold-heat resistance, and heat-and-moisture resistance comprehensively. Furthermore, since the heat-radiation sheet obtained in Examples 1-12 uses both plate-like inorganic particles and spherical inorganic particles as inorganic fillers, in contrast to Comparative Examples 1-5 and Examples 13-14, It can be seen that the heat conductivity, the cold heat resistance and the heat and moisture resistance are more excellent overall.

  Therefore, any of the heat dissipation sheets obtained in each example is expected to be used when, for example, a wiring board and a member that requires heat dissipation such as a heat sink and a housing are joined. . In addition, the heat dissipation sheet obtained in each example is, for example, a lighting device having a substrate on which a light emitting element is mounted and a radiator, a smart phone or a tablet terminal that is required to be thin, an electronic device used for wireless power feeding, etc. It is expected to be used when fixing internal components or dissipating heat.

  The heat dissipating sheet of the present invention is, for example, a lighting device using a light emitting diode (LED) or electroluminescence, a backlight lighting device, a battery such as a solar battery or a lithium ion battery, or a computer such as an IC or CPU. Power components such as parts and modules, power circuits such as inverters, touch panels, electromagnetic shields, smartphones and tablet devices that require thinning, components inside electronic devices used for wireless power supply, etc. In addition, it can be suitably used for graphite sheets, metal foils, processed products thereof, and the like.

Claims (1)

  A heat dissipation sheet comprising a heat dissipation material containing an adhesive resin, an inorganic filler, and a curing agent.