JP2011111544A - Heat-conductive pressure-sensitive adhesive composition, heat-conductive pressure-sensitive adhesive sheet, and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-conductive pressure-sensitive adhesive sheet having heat conductivity, flexibility, flame retardancy and insulating properties with satisfactory balance, to provide a heat-conductive pressure-sensitive adhesive composition used as the base of the sheet and to provide an electronic component provided with the sheet. <P>SOLUTION: In the heat-conductive pressure-sensitive adhesive composition (E) including 100 pts.mass at least one polymer (S) selected from the group consisting of a rubber, an elastomer and a resin, 5 to 35 pts.mass expanded graphite powder (B), 7 to 100 pts.mass condensed phosphate (C), 150 to 500 pts.mass flame retardant heat conductive inorganic compound (D) and 0.02 to 15 pts.mass foaming agent (H), the condensed phosphate (C) has ≥7,000 mPa s viscosity at 25°C and is always a liquid in 15 to 100°C temperature region under atmospheric pressure. The heat-conductive pressure-sensitive adhesive sheet (F) is formed from the heat-conductive pressure-sensitive adhesive composition (E). The electronic component has the sheet. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat conductive pressure-sensitive adhesive composition, a heat conductive pressure-sensitive adhesive sheet formed from the heat conductive pressure-sensitive adhesive composition, and an electronic component including the sheet.

  In recent years, electronic components such as plasma display panels (PDP), integrated circuit (IC) chips, and the like have increased in heat generation as their performance has increased. As a result, there is a need to take measures against functional failures due to temperature rise. In general, a method of diffusing and radiating heat is adopted by attaching a heat sink such as a metal heat sink, heat radiating plate, or heat radiating fin to a heat generating body such as an electronic component. In order to efficiently conduct heat conduction from the heating element to the heat radiating body, various heat conduction sheets are used, but in general, a heat conductive pressure-sensitive adhesive sheet is used for fixing the heating element and the heat radiating element. is needed.

  Such a heat conductive pressure-sensitive adhesive sheet may be required to have other properties (insulation, flame retardancy, flexibility, etc.) depending on the application in addition to tackiness and heat conductivity. In order to improve the performance of a sheet-like member such as a heat conductive pressure-sensitive adhesive sheet, it is conceivable to add various fillers to the composition that forms the sheet. For example, Patent Document 1 discloses a resin composition in which graphite particles and a carbon fiber structure are contained in a thermoplastic resin, and a molded product having excellent heat dissipation and workability is obtained from the resin composition. It is stated that

JP 2008-150595 A

  As described above, the heat conductive pressure-sensitive adhesive sheet is required to have performances other than tackiness and heat conductivity depending on the application. Specifically, insulative properties have been required in order to deal with applications that are applied directly to LED light sources and the like. Furthermore, flexibility and flame retardancy have been required. However, it is difficult to provide a heat conductive pressure-sensitive adhesive sheet having thermal conductivity, flexibility, flame retardancy, and insulation by conventional techniques including the technique disclosed in Patent Document 1. Met. For example, it is conceivable to add expanded graphite powder in order to improve the flame retardancy. However, when a large amount of expanded graphite powder is used, the insulation and the like must be sacrificed. One way to obtain flexibility is to increase the expansion ratio, but there are problems such as a decrease in thermal conductivity.

  Therefore, the present invention provides a heat conductive pressure-sensitive adhesive sheet having a good balance of thermal conductivity, flexibility, flame retardancy, and insulation, a heat conductive pressure-sensitive adhesive composition that is the basis of the sheet, and An object is to provide an electronic component including the sheet.

  As a result of continual research on the heat conductive pressure-sensitive adhesive sheet, the present inventors have found an expanded graphite powder, a condensed phosphate ester satisfying predetermined conditions, a flame retardant heat conductive inorganic compound, and a foaming agent. The present inventors have found that the above-mentioned problems can be solved by molding a quantitatively contained thermally conductive pressure-sensitive adhesive composition into a sheet, and have completed the present invention.

  Thus, according to the first aspect of the present invention, 100 parts by mass of at least one polymer (S) selected from the group consisting of rubber, elastomer and resin, and 5 parts by mass or more and 35 parts by mass or less of expanded graphite powder (B). And 7 to 100 parts by mass of the condensed phosphate ester (C), 150 to 500 parts by mass of the flame-retardant heat conductive inorganic compound (D), and 0.02 or more parts by mass of the foaming agent (H). The condensed phosphate ester (C) has a viscosity at 25 ° C. of 7000 mPa · s or higher and is always liquid in a temperature range of 15 ° C. or higher and 100 ° C. or lower under atmospheric pressure. A conductive pressure sensitive adhesive composition (E) is provided.

  In the heat conductive pressure-sensitive adhesive composition (E) of the first invention, it is preferable that the glass fiber (G) is further contained in an amount of 35 parts by mass or less. When the heat conductive pressure sensitive adhesive composition (E) is made into a heat conductive pressure sensitive adhesive sheet (F) by containing a predetermined amount of glass fiber (G), the heat conductive pressure sensitive adhesive sheet (F). The flame retardancy can be improved.

  In the heat conductive pressure-sensitive adhesive composition (E) of the first invention, the polymer (S) is preferably a (meth) acrylic acid ester polymer (A1). In the present invention, “(meth) acryl” means “acryl and / or methacryl”. When the heat conductive pressure sensitive adhesive composition (E) is made into a heat conductive pressure sensitive adhesive sheet (F) by using the polymer (S) as a (meth) acrylic acid ester polymer (A1), the heat conduction It is easy to impart adhesiveness and flexibility to the pressure-sensitive adhesive sheet (F). Further, the (meth) acrylic acid ester polymer is preferable from the viewpoint that it is easy to handle because the monomer is liquid and is inexpensive.

  In the heat conductive pressure-sensitive adhesive composition (E) of the first invention, the (meth) acrylic acid ester polymer (A1) is present in the presence of the (meth) acrylic acid ester polymer (AP1). It is preferably obtained by polymerizing the acrylate monomer (α1). By setting it as this form, when making a heat conductive pressure sensitive adhesive composition (E) into a heat conductive pressure sensitive adhesive sheet (F), the moldability of this heat conductive pressure sensitive adhesive sheet (F) is improved. be able to.

  Moreover, according to 2nd this invention, the heat conductive pressure sensitive adhesive sheet (F) formed by shape | molding the heat conductive pressure sensitive adhesive composition (E) of 1st this invention in a sheet form is provided. The

  In the heat conductive pressure sensitive adhesive sheet (F) of the second aspect of the present invention, the heat conductive pressure sensitive adhesive composition (E) is composed of a (meth) acrylate polymer (AP1) and a (meth) acrylate ester. Body (α1), and while the heat conductive pressure-sensitive adhesive composition (E) is molded into a sheet or after being formed into a sheet, (meta) in the heat conductive pressure-sensitive adhesive composition (E) ) The thermal conductivity obtained by polymerizing the (meth) acrylic acid ester monomer (α1) in the thermally conductive pressure-sensitive adhesive composition (E) in the presence of the acrylic ester polymer (AP1). The pressure-sensitive adhesive composition (E) is preferably a solidified sheet-like molded body.

  Furthermore, according to 3rd this invention, the electronic component provided with the heat conductive pressure-sensitive-adhesive sheet (F) of 2nd this invention is provided.

  As an electronic component of the third aspect of the present invention, an electroluminescence (EL), a device having a light emitting diode (LED) light source, an automobile power device, a fuel cell, a solar cell, a battery, a mobile phone, a personal digital assistant (PDA), A notebook personal computer, a liquid crystal, a surface conduction electron-emitting device display (SED), a plasma display panel (PDP), an integrated circuit (IC), and the like can be given.

  According to the present invention, a heat conductive pressure-sensitive adhesive sheet having a good balance of thermal conductivity, flexibility, flame retardancy, and insulation, a heat conductive pressure-sensitive adhesive composition that is the basis of the sheet, and An electronic component including the sheet can be provided.

1. Thermally conductive pressure sensitive adhesive composition (E)
The thermally conductive pressure-sensitive adhesive composition (E) of the present invention comprises at least one polymer (S) selected from the group consisting of rubber, elastomer and resin, expanded graphite powder (B), and condensed phosphate ester. It contains a predetermined amount of (C), a flame-retardant thermally conductive inorganic compound (D), and a foaming agent (H), and may further contain a predetermined amount of glass fiber (G). Hereinafter, each of these substances will be described in detail.

<Polymer (S)>
As what comprises a polymer (S), at least 1 type arbitrarily selected from rubber | gum, an elastomer, and resin can be mentioned. And in order to shape | mold the heat conductive pressure-sensitive-adhesive composition (E) of this invention in a sheet form, and to use as a heat conductive pressure-sensitive-adhesive sheet (F), it is adhesive and / or to a polymer (S). It is preferable to provide adhesiveness. In order to provide the polymer (S) with adhesiveness and / or tackiness, the rubber, elastomer and resin are preferably selected from those having adhesiveness and / or tackiness. However, an adhesive agent can be used in combination with rubber, elastomer and resin having no adhesiveness and / or tackiness.

  Specific examples of rubbers, elastomers and resins that can be used in the present invention are listed below.

  Conjugated diene polymers such as natural rubber, polybutadiene rubber, polyisoprene rubber; butyl rubber; styrene-butadiene random copolymer, styrene-isoprene random copolymer, styrene-butadiene-isoprene random copolymer, styrene-butadiene block copolymer Polymer, styrene-isoprene block copolymer, styrene-butadiene-isoprene block copolymer, styrene-isoprene-styrene block copolymer, etc., aromatic vinyl-conjugated diene copolymer; styrene-butadiene copolymer Hydrogenated aromatic vinyl-conjugated diene copolymer, such as hydrogenated product; vinyl cyanide compound-conjugated diene copolymer, such as acrylonitrile-butadiene copolymer rubber, acrylonitrile-isoprene copolymer rubber; acrylonitrile- Hydrogenates of vinyl cyanide compounds-conjugated diene copolymers, such as hydrogenates of tadiene copolymers; vinyl cyanides-aromatic vinyl-conjugated diene copolymers; vinyl cyanide compounds-aromatic vinyl-conjugated Hydrogenated diene copolymer; mixture of vinyl cyanide compound-conjugated diene copolymer and poly (vinyl halide); polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polymethyl methacrylate, polyacrylic Ethyl acetate, polyethyl methacrylate, poly (n-butyl acrylate), poly (n-butyl methacrylate), poly (2-ethylhexyl acrylate), poly (2-ethylhexyl methacrylate), poly [acrylic acid- ( N-butyl acrylate)], poly [acrylic acid- (2-ethylhexyl acrylate)], poly [acrylic acid Acid- (n-butyl acrylate)-(2-ethylhexyl acrylate)], poly [methacrylic acid- (n-butyl acrylate)], poly [methacrylic acid- (2-ethylhexyl acrylate)], poly [methacryl Acid- (n-butyl acrylate)-(2-ethylhexyl acrylate)], poly [acrylic acid-methacrylic acid- (n-butyl acrylate)], poly [acrylic acid-methacrylic acid- (2-ethylhexyl acrylate) )], Poly [acrylic acid-methacrylic acid- (n-butyl acrylate)-(2-ethylhexyl acrylate)], poly (stearyl acrylate), poly (stearyl methacrylate), (meth) acrylic polymers; polyepichloro Polyepihalohydrin rubbers such as hydrin rubber and polyepibromohydrin rubber; polyethylene oxide Polyethylene oxide such as polypropylene oxide; ethylene-propylene-diene copolymer (EPDM); silicone rubber; silicone resin; fluororubber; fluororesin; polyethylene; ethylene-propylene copolymer, ethylene-butene copolymer, etc. Ethylene-α-olefin copolymers; α-olefin polymers such as polypropylene, poly-1-butene and poly-1-octene; polyvinyl halides such as polyvinyl chloride resins and polyvinyl bromide resins Resin; Polyhalogenated vinylidene resin such as polyvinylidene chloride resin and polyvinylidene bromide resin; Epoxy resin; Phenol resin; Polyphenylene ether resin; Polyamide such as nylon-6, nylon-6,6, nylon-6,12 Polyurethane; polyester; And vinyl acetate; poly (ethylene-vinyl alcohol);

  Among the specific examples of the rubber, elastomer and resin described above, styrene-isoprene block copolymer, styrene-isoprene-styrene block copolymer, polyacrylate, poly (n-butyl acrylate), poly (acrylic acid 2 -Ethylhexyl), poly [acrylic acid- (n-butyl acrylate)], poly [acrylic acid- (2-ethylhexyl acrylate)], poly [acrylic acid- (n-butyl acrylate)-(acrylic acid 2- Ethyl hexyl)], poly [methacrylic acid- (n-butyl acrylate)], poly [methacrylic acid- (2-ethylhexyl acrylate)], poly [methacrylic acid- (n-butyl acrylate)-(acrylic acid 2- Ethylhexyl)], poly [acrylic acid-methacrylic acid- (n-butyl acrylate)], poly [acrylic acid] Acid - methacrylic acid - (2-ethylhexyl acrylate)], poly [acrylic acid - methacrylic acid - (n-butyl acrylate) - (2-ethylhexyl acrylate)] is, adhesion, preferred because of its excellent adhesiveness.

  More preferably, poly (n-butyl acrylate), poly (2-ethylhexyl acrylate), poly [acrylic acid- (n-butyl acrylate)], poly [acrylic acid- (2-ethylhexyl acrylate)], Poly [acrylic acid- (n-butyl acrylate)-(2-ethylhexyl acrylate)], poly [methacrylic acid- (n-butyl acrylate)], poly [methacrylic acid- (2-ethylhexyl acrylate)], Poly [methacrylic acid- (n-butyl acrylate)-(2-ethylhexyl acrylate)], poly [acrylic acid-methacrylic acid- (n-butyl acrylate)], poly [acrylic acid-methacrylic acid- (acrylic acid) 2-ethylhexyl)], poly [acrylic acid-methacrylic acid- (n-butyl acrylate)-(2-ethylhexyl acrylate) ], And the like.

  More preferable examples include poly [acrylic acid- (2-ethylhexyl acrylate)], poly [methacrylic acid- (2-ethylhexyl acrylate)], and poly [acrylic acid-methacrylic acid- (2-ethylhexyl acrylate)]. It is done.

  The said substance quoted as a specific example of rubber | gum, an elastomer, and resin may be used individually by 1 type, and may use 2 or more types together.

  Various known agents can be used as the tackifier imparted to the polymer (S) as desired. For example, petroleum resin, terpene resin, phenol resin and rosin resin can be mentioned, and among these, petroleum resin is preferable. These may be used individually by 1 type and may use 2 or more types together.

  Specific examples of petroleum resins include C5 petroleum resins obtained from pentene, pentadiene, isoprene, etc .; C9 petroleum resins obtained from indene, methylindene, vinyltoluene, styrene, α-methylstyrene, β-methylstyrene, etc .; C5-C9 copolymer petroleum resin obtained from monomer; petroleum resin obtained from cyclopentadiene, dicyclopentadiene; hydride of these petroleum resins; maleic anhydride, maleic acid, fumaric acid, (meth) of these petroleum resins And modified petroleum resins modified with acrylic acid, phenol, and the like.

  Examples of terpene resins include α-pinene resins, β-pinene resins, and aromatic-modified terpene resins obtained by copolymerizing terpenes such as α-pinene and β-pinene and aromatic monomers such as styrene. .

  As the phenol resin, a condensate of phenols and formaldehyde can be used. Examples of the phenols include phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin, and the like. These phenols and formaldehyde are subjected to a condensation reaction with an acid catalyst or an acid catalyst. The novolak obtained by this can be illustrated. Moreover, the rosin phenol resin etc. which are obtained by adding phenol to an rosin with an acid catalyst and thermally polymerizing can be illustrated.

  Examples of rosin resins include gum rosin, wood rosin or tall oil rosin, stabilized rosin or polymerized rosin disproportionated or hydrogenated using the rosin, maleic anhydride, maleic acid, fumaric acid, (meth) acrylic acid, Examples thereof include modified rosin modified with phenol and the like, and esterified products thereof.

  The alcohol used for esterification to obtain the esterified product is preferably a polyhydric alcohol, and examples thereof include dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and neopentyl glycol, glycerin, trimethylolethane, Examples include trihydric alcohols such as trimethylolpropane, tetrahydric alcohols such as pentaerythritol and diglycerin, and hexahydric alcohols such as dipentaerythritol. These may be used alone or in combination of two or more. You may use together.

  The softening point of these adhesiveness-imparting agents is not particularly limited, and liquids at room temperature can be appropriately selected from those having a high softening point of 200 ° C. or lower.

((Meth) acrylic acid ester polymer (A1))
As the polymer (S), a (meth) acrylic acid ester polymer (A1) is preferable. The (meth) acrylate polymer (A1) is obtained by polymerizing the (meth) acrylate monomer (α1) in the presence of the (meth) acrylate polymer (AP1). Is particularly preferred. When forming the heat conductive pressure sensitive adhesive composition (E) to form a heat conductive pressure sensitive adhesive sheet (F), or while forming the heat conductive pressure sensitive adhesive composition (E) into a sheet, or After forming into a sheet, the (meth) acrylic acid ester monomer (α1) in the thermally conductive pressure-sensitive adhesive composition (E) is polymerized and converted to a (meth) acrylic acid ester polymer, A (meth) acrylic acid ester polymer (A1) is obtained by mixing and / or partially bonding with the (meth) acrylic acid ester polymer (AP1). The (meth) acrylic acid ester polymer (A1) corresponds to all the (meth) acrylic acid ester polymer components in the heat conductive pressure-sensitive adhesive sheet (F), and the heat conductive pressure-sensitive adhesive sheet (F). It is a concept that comprehensively represents all the (meth) acrylic acid ester polymer components therein.

((Meth) acrylic acid ester polymer (AP1))
Hereinafter, the (meth) acrylic acid ester polymer (AP1) will be described in detail.

  The (meth) acrylic acid ester polymer (AP1) is not particularly limited, but a (meth) acrylic acid ester monomer unit (a1) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, and It is preferable to contain a monomer unit (a2) having an organic acid group.

  The (meth) acrylate monomer (a1m) that gives the unit (a1) of the (meth) acrylate monomer that forms a homopolymer having a glass transition temperature of −20 ° C. or lower is not particularly limited. However, for example, ethyl acrylate (the glass transition temperature of the homopolymer is -24 ° C), propyl acrylate (-37 ° C), butyl acrylate (-54 ° C), sec-butyl acrylate (same as above) -22 ° C), heptyl acrylate (-60 ° C), hexyl acrylate (-61 ° C), octyl acrylate (-65 ° C), 2-ethylhexyl acrylate (-50 ° C), acrylic acid 2 -Methoxyethyl (same -50 ° C), 3-methoxypropyl acrylate (same -75 ° C), 3-methoxybutyl acrylate (same -56 ° C), 2-ethoxymethyl acrylate (same -50) ), Octyl methacrylate (same -25 ° C.), and the like decyl methacrylate (same -49 ° C.).

  These (meth) acrylic acid ester monomers (a1m) may be used individually by 1 type, and may use 2 or more types together.

  In these (meth) acrylate monomers (a1m), the monomer unit (a1) derived therefrom is preferably 80% by mass or more and 99.9% by mass in the (meth) acrylate polymer (AP1). % Or less, more preferably 85% by mass or more and 99.5% by mass or less. When the amount of the (meth) acrylic acid ester monomer (a1m) is within the above range, the heat-sensitive pressure-sensitive adhesive sheet (F) obtained therefrom is excellent in pressure-sensitive adhesiveness around room temperature.

  The monomer (a2m) that gives the monomer unit (a2) having an organic acid group is not particularly limited, and representative examples thereof include organic acid groups such as a carboxyl group, an acid anhydride group, and a sulfonic acid group. In addition to these, monomers containing sulfenic acid groups, sulfinic acid groups, phosphoric acid groups, and the like can also be used.

  Specific examples of the monomer having a carboxyl group include, for example, α, β-ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and α, such as itaconic acid, maleic acid, and fumaric acid. In addition to β-ethylenically unsaturated polyvalent carboxylic acid, α, β-ethylenically unsaturated polyvalent carboxylic acid partial esters such as methyl itaconate, butyl maleate and propyl fumarate can be exemplified. Moreover, what has group which can be induced | guided | derived to a carboxyl group by hydrolysis etc., such as maleic anhydride and itaconic anhydride, can be used similarly.

  Specific examples of the monomer having a sulfonic acid group include allyl sulfonic acid, methallyl sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, α, β-unsaturated sulfonic acid such as acrylamide-2-methylpropane sulfonic acid, And salts thereof.

  Among these monomers having an organic acid group, monomers having a carboxyl group are more preferable, and acrylic acid and methacrylic acid are particularly preferable. These are industrially inexpensive and can be easily obtained, have good copolymerizability with other monomer components, and are preferable in terms of productivity. These monomers (a2m) having an organic acid group may be used alone or in combination of two or more.

  In the monomer (a2m) having these organic acid groups, the monomer unit (a2) derived therefrom is 0.1% by mass or more and 20% by mass or less in the (meth) acrylic acid ester polymer (AP1). Preferably, it is used for the polymerization in such an amount that it is 0.5 mass% or more and 15 mass% or less. In use within the above range, the viscosity of the polymerization system during polymerization can be maintained within an appropriate range.

  The monomer unit (a2) having an organic acid group is introduced into the (meth) acrylate polymer by polymerization of the monomer (a2m) having an organic acid group as described above. Although simple and preferable, an organic acid group may be introduced by a known polymer reaction after the (meth) acrylic acid ester polymer is formed.

  The (meth) acrylic acid ester polymer (AP1) may contain a monomer unit (a3) derived from a monomer (a3m) containing a functional group other than an organic acid group.

  Examples of the functional group other than the organic acid group include a hydroxyl group, an amino group, an amide group, an epoxy group, and a mercapto group.

  Examples of the monomer having a hydroxyl group include (meth) acrylic acid hydroxyalkyl esters such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate.

  Examples of the monomer containing an amino group include N, N-dimethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and aminostyrene.

  Examples of monomers having an amide group include α, β-ethylenically unsaturated carboxylic acid amide monomers such as acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, and N, N-dimethylacrylamide. Can be mentioned.

  Examples of the monomer having an epoxy group include glycidyl (meth) acrylate and allyl glycidyl ether.

  The monomer (a3m) containing a functional group other than the organic acid group may be used alone or in combination of two or more.

  The monomer (a3m) having a functional group other than these organic acid groups is such that the monomer unit (a3) derived therefrom is 10% by mass or less in the (meth) acrylic acid ester polymer (AP1). It is preferred to be used in the polymerization in an appropriate amount. By using 10 mass% or less of monomer (a3m), the viscosity at the time of superposition | polymerization can be kept appropriate.

  The (meth) acrylic acid ester polymer (AP1) has a (meth) acrylic acid ester monomer unit (a1) and an organic acid group for forming a homopolymer having a glass transition temperature of −20 ° C. or lower. In addition to the monomer unit (a2) and the monomer unit (a3) containing a functional group other than the organic acid group, it is derived from a monomer (a4m) copolymerizable with these monomers. The monomer unit (a4) may be contained. A monomer (a4m) may be used individually by 1 type, and may use 2 or more types together.

  The amount of the monomer unit (a4) derived from the monomer (a4m) is preferably 10% by mass or less, more preferably 5% by mass or less of the acrylate polymer (AP1).

  Although a monomer (a4m) is not specifically limited, As a specific example, (meth) acrylic acid ester monomer (a1m) other than (meth) acrylate monomer (a1m) which molds a homopolymer having a glass transition temperature of −20 ° C. or lower. ) Acrylic acid ester monomer, α, β-ethylenically unsaturated polyvalent carboxylic acid complete ester, alkenyl aromatic monomer, conjugated diene monomer, non-conjugated diene monomer, vinyl cyanide monomer Carboxylic acid unsaturated alcohol ester, olefinic monomer and the like.

  Specific examples of the (meth) acrylate monomer other than the (meth) acrylate monomer (a1m) for forming a homopolymer having a glass transition temperature of −20 ° C. or lower include methyl acrylate (single The glass transition temperature of the polymer is 10 ° C., methyl methacrylate (105 ° C.), ethyl methacrylate (63 ° C.), propyl methacrylate (25 ° C.), butyl methacrylate (20 ° C.), and the like. be able to.

  Specific examples of the α, β-ethylenically unsaturated polyvalent carboxylic acid complete ester include dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl itaconate and the like.

  Specific examples of the alkenyl aromatic monomer include styrene, α-methylstyrene, methyl α-methylstyrene, vinyl toluene, and divinylbenzene.

  Specific examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene (synonymous with isoprene), 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. , 2-chloro-1,3-butadiene, cyclopentadiene, and the like.

  Specific examples of the non-conjugated diene monomer include 1,4-hexadiene, dicyclopentadiene, ethylidene norbornene and the like.

  Specific examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile and the like.

  Specific examples of the carboxylic acid unsaturated alcohol ester monomer include vinyl acetate.

  Specific examples of the olefin monomer include ethylene, propylene, butene, pentene and the like.

  The weight average molecular weight (Mw) of the (meth) acrylic acid ester polymer (AP1) is preferably in the range of 100,000 to 400,000 as measured by gel permeation chromatography (GPC method). It is more preferable that it is in the range of 300 to 300,000.

  The (meth) acrylic acid ester polymer (AP1) is a (meth) acrylic acid ester monomer (a1m), a monomer having an organic acid group, which forms a homopolymer having a glass transition temperature of −20 ° C. or lower. (A2m), a monomer containing a functional group other than an organic acid group (a3m) used as required, and a monomer copolymerizable with these monomers used as needed ( a4m) can be obtained particularly preferably by copolymerization.

  The polymerization method is not particularly limited, and may be any of solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization and the like, and may be other methods. Solution polymerization is preferred, and among them, solution polymerization using a carboxylic acid ester such as ethyl acetate or ethyl lactate or an aromatic solvent such as benzene, toluene or xylene as the polymerization solvent is more preferred.

  In the polymerization, the monomer may be added in portions to the polymerization reaction vessel, but it is preferable to add the whole amount at once.

  The method for initiating the polymerization is not particularly limited, but it is preferable to use a thermal polymerization initiator as the polymerization initiator. The thermal polymerization initiator is not particularly limited, and may be either a peroxide or an azo compound.

  Peroxide polymerization initiators include hydroperoxides such as t-butyl hydroperoxide, peroxides such as benzoyl peroxide and cyclohexanone peroxide, and persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate. Can be mentioned. These peroxides can also be used as a redox catalyst in appropriate combination with a reducing agent.

  As the azo compound polymerization initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile) And so on.

  Although the usage-amount of a polymerization initiator is not specifically limited, It is preferable that it is the range of 0.01 mass part or more and 50 mass parts or less with respect to 100 mass parts of monomers.

  Other polymerization conditions (polymerization temperature, pressure, stirring conditions, etc.) of these monomers are not particularly limited.

  After completion of the polymerization reaction, the obtained polymer is separated from the polymerization medium as necessary. The separation method is not particularly limited. In the case of solution polymerization, the (meth) acrylic acid ester polymer (AP1) can be obtained by placing the polymerization solution under reduced pressure and distilling off the polymerization solvent.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (AP1) can be controlled by appropriately adjusting the amount of the polymerization initiator used in the polymerization and the amount of the chain transfer agent.

((Meth) acrylic acid ester monomer (α1))
As described above, as the polymer (S), (meth) acrylic acid ester polymer (A1) is preferable, and (meth) acrylic acid ester polymer (A1) is (meth) acrylic acid ester. Those obtained by polymerizing the (meth) acrylic acid ester monomer (α1) in the presence of the polymer (AP1) are particularly preferred.

  The (meth) acrylic acid ester monomer (α1) is not particularly limited as long as it contains a (meth) acrylic acid ester monomer, but a homopolymer having a glass transition temperature of −20 ° C. or lower. It is preferable to contain the (meth) acrylic acid ester monomer (a5m) to shape | mold.

  As an example of the (meth) acrylic acid ester monomer (a5m) for forming a homopolymer having a glass transition temperature of −20 ° C. or lower, it is used for the synthesis of a (meth) acrylic acid ester polymer (AP1) (meta ) The same (meth) acrylate monomer as the acrylate monomer (a1m) can be mentioned. A (meth) acrylic acid ester monomer (a5m) may be used individually by 1 type, and may use 2 or more types together.

  The (meth) acrylic acid ester monomer (α1) may be used as a mixture of the (meth) acrylic acid ester monomer (a5m) and a monomer copolymerizable therewith.

  Particularly preferred (meth) acrylate monomer (α1) has a (meth) acrylate monomer (a5m) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, and an organic acid group. It consists of a monomer (a6m) and a monomer (a7m) copolymerizable therewith.

  The ratio of the (meth) acrylate monomer (a5m) in the (meth) acrylate monomer (α1) is preferably 69.9% by mass to 99.8% by mass, more preferably 74.5%. It is not less than 98.5% by mass. When the ratio of the (meth) acrylic acid ester monomer (a5m) in the (meth) acrylic acid ester monomer (α1) is 69.9% by mass or more and 99.8% by mass or less, the heat conductive pressure sensitive The adhesive sheet (F) is excellent in pressure-sensitive adhesiveness and flexibility.

  Examples of the monomer (a6m) having an organic acid group include a monomer having the same organic acid group as that exemplified as the monomer (a2m) used for the synthesis of the (meth) acrylic acid ester polymer (AP1). A polymer can be mentioned. As the monomer having an organic acid group (a6m), one type may be used alone, or two or more types may be used in combination.

  The ratio of the monomer (a6m) having an organic acid group in the (meth) acrylic acid ester monomer (α1) is preferably 0.1% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 25% by mass. % Or less. When the ratio of the monomer (a6m) in the (meth) acrylate monomer (α1) is 0.1% by mass or more and 30% by mass or less, the hardness of the heat conductive pressure-sensitive adhesive sheet (F) is It becomes appropriate and the pressure-sensitive adhesiveness at high temperature (100 ° C.) is good.

  The (meth) acrylic acid ester monomer (α1) is a monomer capable of copolymerizing with the (meth) acrylic acid ester monomer (a5m) and the monomer having an organic acid group (a6m). The body (a7m) is preferably used in the range of 0.1% by mass to 20% by mass, more preferably 0.5% by mass to 15% by mass.

  Examples of the monomer (a7m) include a monomer (a3m), a monomer (a4m) used in the synthesis of the (meth) acrylic acid ester polymer (AP1), and a polyfunctional monomer shown below. The monomer similar to what is illustrated as a body can be mentioned.

  As the copolymerizable monomer (a7m), as described above, a polyfunctional monomer having two or more polymerizable unsaturated bonds can also be used. By copolymerizing the polyfunctional monomer, intramolecular and / or intermolecular crosslinking can be introduced into the copolymer to increase the cohesive force as a pressure-sensitive adhesive.

  Polyfunctional monomers include 1,6-hexanediol di (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, polyethylene glycol di (meth) ) Acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ditrimethylolpropane tri ( Multifunctional (meth) acrylates such as (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 2,4-bis (trichloromethyl) Other substituted triazines, such as 6-p-methoxystyrene-5-triazine, etc. monoethylenically unsaturated aromatic ketones such as 4-acryloxy benzophenone can be used. Among these, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol tetra (meth) acrylate are preferable.

  The (meth) acrylic acid ester monomer (α1) preferably contains the above polyfunctional monomer. The polyfunctional monomer is used as all or part of the monomer (a7m). As the polyfunctional monomer, the (meth) acrylic acid ester monomer (α1) is 100% by mass. Preferably, it is contained in an amount of 0.1 to 5% by mass, more preferably 0.5 to 3% by mass.

  The amount of the (meth) acrylic acid ester monomer (α1) contained in the heat conductive pressure-sensitive adhesive composition (E) is the lower limit with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (AP1). Is preferably 10 parts by mass, more preferably 20 parts by mass, and even more preferably 50 parts by mass. Moreover, it is preferable that an upper limit is 150 mass parts, It is more preferable that it is 100 mass parts, It is further more preferable that it is 80 mass parts. When the amount of the (meth) acrylic acid ester monomer (α1) contained in the heat conductive pressure-sensitive adhesive composition (E) is less than 10 parts by mass or more than 150 parts by mass, a heat conductive pressure-sensitive adhesive sheet ( The pressure-sensitive adhesive retention of F) may be inferior.

  When the heat conductive pressure sensitive adhesive sheet (F) is formed, the (meth) acrylic acid ester monomer (α1) in the heat conductive pressure sensitive adhesive composition (E) is polymerized. In order to accelerate the polymerization, the thermally conductive pressure-sensitive adhesive composition (E) is added to the (meth) acrylic acid ester polymer (AP1) and the (meth) acrylic acid ester monomer (α1), It preferably contains a polymerization initiator.

  Examples of the polymerization initiator include a photopolymerization initiator, an azo thermal polymerization initiator, an organic peroxide thermal polymerization initiator, and the like. From the viewpoint of the adhesive strength of the obtained heat conductive pressure-sensitive adhesive sheet (F). Therefore, an organic peroxide thermal polymerization initiator is preferably used.

  Various known photopolymerization initiators can be used as the photopolymerization initiator. Among these, a phosphine oxide compound is preferable. Examples of the phosphine oxide compound that is a preferred photopolymerization initiator include bis (2,4,6-trimethylbenzyl) phenylphosphine oxide and 2,4,6-trimethylbenzyldiphenylphosphine oxide.

  As the azo thermal polymerization initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile) ) And the like.

  As the organic peroxide thermal polymerization initiator, hydroperoxide such as t-butyl hydroperoxide, benzoyl peroxide, cyclohexanone peroxide, 1,6-bis (t-butylperoxycarbonyloxy) hexane, 1,1-bis ( Examples thereof include peroxides such as (t-butylperoxy) -3,3,5-trimethylcyclohexanone, but it is preferable not to release volatile substances that cause odor during thermal decomposition. Among organic peroxide thermal polymerization initiators, those having a one-minute half-life temperature of 100 ° C. or more and 170 ° C. or less are preferable.

  The amount of the polymerization initiator such as the organic peroxide thermal polymerization initiator used is preferably 0.1 parts by mass, more preferably 100 parts by mass with respect to 100 parts by mass of the (meth) acrylate monomer (α1). The upper limit is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 15 parts by mass.

  The polymerization conversion rate of the (meth) acrylic acid ester monomer (α1) is preferably 95% by mass or more. If the polymerization conversion rate is too low, a monomer odor remains in the obtained heat conductive pressure-sensitive adhesive sheet (F), which is not preferable.

<Expanded graphite powder (B)>
As an example of the expanded graphite powder (B) that can be used in the present invention, acid-treated graphite is heat-treated at 500 ° C. to 1200 ° C. to expand to 100 ml / g to 300 ml / g, and then pulverized. What was obtained through the process containing this can be mentioned. More preferably, the graphite is treated with a strong acid, sintered in an alkali, and then again treated with a strong acid at 500 ° C. to 1200 ° C. to remove the acid and to 100 ml / g to 300 ml / g. What was obtained through the process including expanding and then crushing can be mentioned. The temperature of the heat treatment is particularly preferably 800 ° C to 1000 ° C.

  The average particle size of the expanded graphite powder (B) used in the present invention is preferably 30 μm to 500 μm, more preferably 50 μm to 400 μm, and still more preferably 80 μm to 300 μm. When the average particle size of the expanded graphite powder (B) is less than 30 μm, the thermal conductivity of the heat conductive pressure-sensitive adhesive sheet (F) tends to be low. On the other hand, when the average particle diameter of the expanded graphite powder (B) exceeds 500 μm, the expanded graphite powder (B) exists in a large domain on the surface of the heat conductive pressure-sensitive adhesive sheet (F), and thus the adherend is increased. There is a possibility that voids are easily formed at the interface with the body, the thermal conductivity and adhesiveness of the heat conductive pressure-sensitive adhesive sheet (F) may be reduced, and the moldability may be deteriorated.

  The average particle size of the expanded graphite powder (B) is measured using a laser-type particle size measuring machine (manufactured by Seishin Enterprise Co., Ltd.) and a micro-sorting control method (measuring particles are allowed to pass only within the measurement region to ensure measurement reliability. (Measure to improve). In this measurement method, 0.01 g to 0.02 g of the expanded graphite powder (B) to be measured is flowed into the cell, so that the expanded graphite powder (B) flowing into the measurement region has a semiconductor with a wavelength of 670 nm. By irradiating the laser beam and measuring the scattering and diffraction of the laser beam at that time, the average particle size and particle size distribution are calculated from the Franhofer diffraction principle, and the results are displayed.

  The amount of the expanded graphite powder (B) contained in the heat conductive pressure-sensitive adhesive composition (E) is 5 parts by mass or more and 35 parts by mass or less based on 100 parts by mass of the polymer (S). The upper limit is preferably 33 parts by mass, and more preferably 30 parts by mass. The lower limit is preferably 8 parts by mass, and more preferably 10 parts by mass. If content of expanded graphite powder (B) is less than 5 mass parts, it exists in the tendency for the heat conductivity of a heat conductive pressure-sensitive-adhesive sheet (F) to be inferior. On the other hand, if the content of the expanded graphite powder (B) exceeds 35 parts by mass, it becomes difficult to form the heat conductive pressure sensitive adhesive composition (E) into a sheet, and the heat conductive pressure sensitive adhesive laminated sheet (F ) May be difficult to obtain.

<Condensed phosphate ester (C)>
A heat conductive pressure sensitive adhesive sheet (F) obtained from the heat conductive pressure sensitive adhesive composition (E) by containing a predetermined amount of the condensed phosphate ester (C) in the heat conductive pressure sensitive adhesive composition (E). ) Flame retardancy can be improved. The condensed phosphate ester (C) that can be used in the present invention has a viscosity at 25 ° C. of 7000 mPa · s or more. When the viscosity of the condensed phosphate ester (C) is too low, the moldability of the heat conductive pressure-sensitive adhesive sheet (F) is deteriorated. In the present invention, the “viscosity” of the condensed phosphate ester (C) means a viscosity measured by the method described below.

(Method for measuring viscosity of condensed phosphate ester (C))
The viscosity of the condensed phosphate ester (C) was measured using a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) according to the following procedure.
(1) Weigh 300 ml of the condensed phosphate ester (C) in a room temperature environment and place it in a 500 ml container.
(2) Stirring rotor No. Select one from 1, 2, 3, 4, 5, 6, and 7 and attach to the viscometer.
(3) The container containing the condensed phosphate ester (C) is placed on the viscometer, and the rotor is submerged in the condensed phosphate ester (C) in the container. At this time, it sinks so that the dent used as a mark of a rotor may just come to the liquid interface of condensed phosphate ester (C).
(4) The rotation speed is selected from 20, 10, 4, and 2.
(5) Turn on the stirring switch and read the value after 1 minute.
(6) The value obtained by multiplying the read numerical value by the coefficient A is the viscosity [mPa · s].
The coefficient A is the selected rotor No. as shown in Table 1 below. And the number of revolutions.

  In addition, the condensed phosphate ester (C) used in the present invention is always liquid in a temperature range of 15 ° C. or more and 100 ° C. or less under atmospheric pressure. If the condensed phosphate ester (C) is not liquid when mixed, the workability is poor, and it becomes difficult to form a sheet of the heat conductive pressure-sensitive adhesive composition (E). When obtaining the heat conductive pressure sensitive adhesive composition (E) containing the condensed phosphate ester (C), the heat conductive pressure sensitive adhesive composition (E) is usually configured in an environment of 15 ° C. or higher and 100 ° C. or lower. Mix each substance. If the temperature at the time of mixing is too low, it may be lower than the glass transition temperature of the polymer (S). If it is too high, the volatilization of the monomer or the polymerization reaction will start, so the environment and workability are poor. There is a risk of becoming.

  Specific examples of the condensed phosphate ester (C) that satisfies the conditions described so far include aromatic condensed phosphate esters such as 1,3-phenylenebis (diphenylphosphate) and bisphenol Abis (diphenylphosphate); polyoxy And halogen-containing condensed phosphates such as alkylene bisdichloroalkyl phosphate; non-aromatic non-halogen-based condensed phosphates; One of these may be used alone, or two or more may be used in combination. Among these, aromatic condensed phosphates are preferred because of their relatively low specific gravity, no danger of releasing harmful substances (such as halogens), and availability, and 1,3-phenylenebis (diphenyl phosphate). ), Bisphenol A bis (diphenyl phosphate) is more preferred.

  The amount of the condensed phosphate ester (C) contained in the heat conductive pressure-sensitive adhesive composition (E) is 7 parts by mass or more and 100 parts by mass or less, based on 100 parts by mass of the polymer (S). The upper limit is preferably 80 parts by mass, and more preferably 60 parts by mass. The lower limit is preferably 20 parts by mass, and more preferably 30 parts by mass. If the content of the condensed phosphate ester (C) exceeds 100 parts by mass, it becomes difficult to form a thermally conductive pressure-sensitive adhesive composition (E), and if it is less than 7 parts by mass, the thermal conductivity is felt. The flame retardancy of the pressure-adhesive sheet (F) tends to be insufficient.

  By containing the condensed phosphate ester (C) in the heat conductive pressure-sensitive adhesive composition (E), the flame retardancy of the heat conductive pressure-sensitive adhesive sheet (F) can be improved. However, if the content of the condensed phosphate ester (C) is too large, there is a possibility that problems such as lowering the tackiness of the heat conductive pressure-sensitive adhesive sheet (F) may occur. In the present invention, the heat conductive pressure sensitive adhesive composition (E) contains a foaming agent (H) and the like described later in detail, thereby improving the flame retardancy of the heat conductive pressure sensitive adhesive sheet (F), The content of the condensed phosphate ester (C) can be suppressed. Therefore, according to the heat conductive pressure sensitive adhesive composition (E) of the present invention, the flame retardant of the heat conductive pressure sensitive adhesive sheet (F) while maintaining the tackiness of the heat conductive pressure sensitive adhesive sheet (F). Can be improved.

<Flame-retardant thermally conductive inorganic compound (D)>
The flame retardant thermally conductive inorganic compound (D) that can be used in the present invention is not particularly limited, and specific examples thereof include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, dihydrate gypsum, and boron. Examples thereof include zinc acid, kaolin clay, calcium aluminate, calcium carbonate, aluminum carbonate, and dawsonite. A flame-retardant heat conductive inorganic compound (D) may be used individually by 1 type, and may use 2 or more types together.

  The shape of the flame retardant thermally conductive inorganic compound (D) is not particularly limited, and may be any of a spherical shape, a needle shape, a fiber shape, a scale shape, a dendritic shape, a flat plate shape, and an indefinite shape.

  Among the flame retardant thermally conductive inorganic compounds (D), aluminum hydroxide is particularly preferable. By using aluminum hydroxide, excellent flame retardancy can be imparted to the heat conductive pressure-sensitive adhesive sheet (F).

  As the aluminum hydroxide, one having a particle diameter of usually 0.2 μm to 150 μm, preferably 0.7 μm to 100 μm is used. Moreover, it is preferable to have an average particle diameter of 1 μm to 80 μm. When the average particle size is less than 1 μm, the viscosity of the heat conductive pressure-sensitive adhesive composition (E) is increased, and at the same time, the hardness is increased, and the shape followability of the heat conductive pressure-sensitive adhesive sheet (F) is decreased. The thermal conductivity tends to be low. On the other hand, when the average particle size exceeds 80 μm, the surface of the heat conductive pressure-sensitive adhesive sheet (F) is roughened, and the shape followability to the adherend may be lowered.

  The amount of the flame retardant thermally conductive inorganic compound (D) contained in the thermally conductive pressure-sensitive adhesive composition (E) is 150 parts by mass or more and 500 parts by mass or less based on 100 parts by mass of the polymer (S). . The upper limit is preferably 480 parts by mass, more preferably 460 parts by mass, and even more preferably 350 parts by mass. The lower limit is preferably 170 parts by mass, more preferably 190 parts by mass, and even more preferably 250 parts by mass. When the content of the flame-retardant heat conductive inorganic compound (D) exceeds 500 parts by mass, the hardness of the heat conductive pressure-sensitive adhesive sheet (F) increases and the shape following property tends to decrease. On the other hand, if the content of the flame-retardant heat-conductive inorganic compound (D) is less than 150 parts by mass, the flame-retardant property of the heat-conductive pressure-sensitive adhesive sheet (F) may be inferior.

<Foaming agent (H)>
By containing a predetermined amount of the foaming agent (H) in the heat conductive pressure sensitive adhesive composition (E), the heat conductive pressure sensitive adhesive sheet (F) obtained from the heat conductive pressure sensitive adhesive composition (E) Flame retardancy can be further improved. As the foaming agent (H), a thermally decomposable foaming agent is preferable. Furthermore, as a thermally decomposable foaming agent, what has a decomposition start temperature of 80 degreeC or more and 500 degrees C or less is preferable, and what has a decomposition start temperature of 120 degreeC or more and 300 degrees C or less is more preferable.

  Specific examples of such thermally decomposable blowing agents include 4,4'-oxybis (benzenesulfonyl hydrazide), azodicarboxamide and the like. A foaming system having a thermal decomposition start temperature of 500 ° C. or lower by mixing a predetermined amount of a foaming aid described later with a foaming agent having a thermal decomposition start temperature higher than 500 ° C. can be similarly used as a thermally decomposable foaming agent.

  Examples of the foaming aid include zinc stearate, a mixture of stearic acid and zinc white (zinc oxide), zinc laurate, a mixture of lauric acid and zinc white, zinc palmitate, a mixture of palmitic acid and zinc white, stearin Examples include sodium acid, sodium laurate, sodium palmitate, potassium stearate, potassium laurate, and potassium palmitate.

  The amount of the foaming agent (H) contained in the heat conductive pressure-sensitive adhesive composition (E) is 0.02 parts by mass or more and 15 parts by mass or less based on 100 parts by mass of the polymer (S). The upper limit is preferably 5 parts by mass, more preferably 1 part by mass, and still more preferably 0.5 parts by mass. The lower limit is preferably 0.03 parts by mass, more preferably 0.05 parts by mass, and even more preferably 0.1 parts by mass. If content of a foaming agent (H) exceeds 15 mass parts, there exists a possibility of inhibiting heat conduction. On the other hand, if it is less than 0.02 mass part, it exists in the tendency for the effect which improves the flame retardance of a heat conductive pressure-sensitive-adhesive sheet (F) to become inadequate.

<Glass fiber (G)>
The glass fiber (G) that can be used in the present invention preferably has a fiber length of 0.1 mm to 4 mm. If the length of the glass fiber is less than 0.1 mm, when the heat conductive pressure sensitive adhesive composition (E) is used as the heat conductive pressure sensitive adhesive sheet (F), the heat conductive pressure sensitive adhesive sheet ( F) It tends to be difficult to obtain the effect of increasing the insulation (decreasing electrical conductivity). On the other hand, when the length of the glass fiber exceeds 4 mm, when the heat conductive pressure sensitive adhesive composition (E) is used as the heat conductive pressure sensitive adhesive sheet (F), the heat conductive pressure sensitive adhesive sheet (F ) Tends to decrease the thermal conductivity, and tends to be difficult to mold.

  It is preferable that the quantity of the glass fiber (G) contained in a heat conductive pressure sensitive adhesive composition (E) is 35 mass parts or less by making a polymer (S) into 100 mass parts. The upper limit is more preferably 25 parts by mass and even more preferably 15 parts by mass. The lower limit is more preferably 2 parts by mass, and still more preferably 5 parts by mass. When the amount of the glass fiber (G) contained in the heat conductive pressure-sensitive adhesive composition (E) exceeds 35 parts by mass, the heat conductive pressure-sensitive adhesive composition (E) to the heat conductive pressure-sensitive adhesive sheet ( F) tends to be difficult to mold.

<Other thermally conductive inorganic compounds>
The heat conductive pressure-sensitive adhesive composition (E) of the present invention may contain a heat conductive inorganic compound other than the expanded graphite powder (B) and the flame retardant heat conductive inorganic compound (D) as an optional component. it can. The heat conductive inorganic compound is illustrated below.

(PITCH carbon fiber (I))
The PITCH-based carbon fiber (I) is a carbon fiber that uses pitch (by-products such as petroleum, coal, coal tar) as a raw material, and has a feature of high thermal conductivity. When the PITCH-based carbon fiber (I) is contained in the heat conductive pressure-sensitive adhesive composition (E), the content thereof is preferably 400 parts by mass or less, more preferably 100 parts by mass or less, based on 100 parts by mass of the polymer (S). Is preferably 300 parts by mass or less, more preferably 270 parts by mass or less. When the content of the PITCH-based carbon fiber (I) exceeds 400 parts by mass, the heat conductive pressure-sensitive adhesive composition (E) is used as the heat conductive pressure-sensitive adhesive sheet (F). It exists in the tendency for the surface state of an adhesive sheet (F) to worsen.

<Other ingredients>
The heat conductive pressure-sensitive adhesive composition (E) may further contain various known additives such as an external cross-linking agent, a pigment, other fillers, an anti-aging agent, and a thickener, if necessary. It can contain in the range which does not impair an effect.

(External crosslinking agent)
The heat conductive pressure sensitive adhesive composition (E) is added with an external cross-linking agent in order to increase the cohesive force as a pressure sensitive adhesive and improve the heat resistance, and the (meth) acrylic acid ester polymer. A crosslinked structure can be introduced into a polymer obtained by polymerizing the (meth) acrylic acid ester monomer (α1) in the presence of (AP1).

  Examples of external crosslinking agents include polyfunctional isocyanate crosslinking agents such as tolylene diisocyanate, trimethylolpropane diisocyanate, diphenylmethane triisocyanate; epoxy crosslinking such as diglycidyl ether, polyethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether Melamine resin crosslinking agent; amino resin crosslinking agent; metal salt crosslinking agent; metal chelate crosslinking agent; peroxide crosslinking agent;

  The external crosslinking agent is obtained by polymerizing the (meth) acrylic acid ester monomer (α1) in the presence of the (meth) acrylic acid ester polymer (AP1), and then added to this. By performing heat treatment or radiation irradiation treatment, a crosslink is formed within and / or between molecules of the copolymer.

(Other)
The pigment can be used regardless of organic type or inorganic type such as carbon black and titanium dioxide. Examples of other fillers include inorganic compounds such as clay. You may add nanoparticles, such as fullerene and a carbon nanotube. Antioxidants such as polyphenols, hydroquinones, and hindered amines can be used as the anti-aging agent because they are likely to inhibit radical polymerization and are not usually used. As the thickener, inorganic polymer fine particles such as acrylic polymer particles and fine silica, and reactive inorganic compounds such as magnesium oxide can be used.

2. Thermally conductive pressure sensitive adhesive sheet (F)
The heat conductive pressure sensitive adhesive sheet (F) of the present invention is a sheet-like form of the heat conductive pressure sensitive adhesive composition (E). A heat conductive pressure sensitive adhesive composition (E) can be shape | molded in a sheet form, and it can be set as a heat conductive pressure sensitive adhesive sheet (F). When the heat conductive adhesive composition (E) is formed into a sheet, it is preferably heated.

  In the heat conductive pressure-sensitive adhesive sheet (F) of the present invention, preferably, the heat conductive pressure-sensitive adhesive composition (E) is a (meth) acrylate polymer (AP1) and a (meth) acrylate ester. The (meth) acrylic acid ester polymer (AP1), while the body (α1) is contained and the thermally conductive pressure-sensitive adhesive composition (E) is molded into a sheet or after being molded into a sheet The solid molded sheet-like molded body of the thermally conductive pressure-sensitive adhesive composition (E) obtained by polymerizing the (meth) acrylic acid ester monomer (α1) below.

  However, when the content of the liquid component typified by a monomer or the like in the heat conductive pressure-sensitive adhesive composition (E) is 5% by mass or less, the heat conductive pressure-sensitive adhesive composition (E ) Can be regarded as substantially equivalent to the case of solidification. In fact, it can be considered that the thermally conductive pressure-sensitive adhesive composition (E) that does not contain a liquid component such as the (meth) acrylic acid ester monomer (α1) is equivalent to the case where it is solidified.

  In the heat conductive pressure-sensitive adhesive composition (E), when the content of a liquid component represented by a monomer or the like in the heat conductive pressure-sensitive adhesive composition (E) is 5% by mass or less. The heat conductive pressure-sensitive adhesive composition (E) is molded as it is without solidifying the liquid component (for example, polymerization of the monomer), and the heat conductive pressure-sensitive adhesive sheet ( F).

  The heat conductive pressure-sensitive adhesive sheet (F) of the present invention may be composed only of the heat conductive pressure-sensitive adhesive composition (E) or a solidified product thereof, and is formed on a substrate and one or both surfaces thereof. Alternatively, it may be a composite comprising the heat conductive pressure-sensitive adhesive composition (E) or a solidified product thereof.

  Although the thickness of the layer of the heat conductive pressure sensitive adhesive composition (E) or its solidified material in the heat conductive pressure sensitive adhesive sheet (F) of this invention is not specifically limited, It is preferable that it is 100 micrometers-3000 micrometers. If the thickness is less than 100 μm, air is likely to be entrained when affixing to the heating element and the radiator, and as a result, sufficient thermal conductivity may not be obtained or workability in the process of affixing to the adherend may be inferior. On the other hand, when it is thicker than 3000 μm, the thermal resistance in the thickness direction of the heat conductive pressure-sensitive adhesive sheet (F) is increased, and there is a possibility that the heat dissipation is impaired.

  When the layer of the heat conductive pressure sensitive adhesive composition (E) or its solidified product is molded on one side or both sides of the base material, the base material is not particularly limited.

  Specific examples of the substrate include metals having excellent thermal conductivity such as aluminum, copper, stainless steel, and beryllium copper, and foils of alloys and polymers having excellent thermal conductivity such as thermal conductive silicone. A sheet-like material, a heat conductive plastic film containing a heat conductive filler, various nonwoven fabrics, glass cloth, a honeycomb structure, or the like can be used.

  Plastic films include polyimide, polyethylene terephthalate, polyethylene naphthalate, polytetrafluoroethylene, polyether ketone, polyethersulfone, polymethylpentene, polyetherimide, polysulfone, polyphenylene sulfide, polyamideimide, polyesterimide, aromatic polyamide, etc. A film made of a heat-resistant polymer can be used.

  The method for forming the heat conductive pressure-sensitive adhesive composition (E) or the solidified product thereof into a sheet is not particularly limited. Suitable methods include, for example, a casting method in which the heat conductive pressure-sensitive adhesive composition (E) is applied onto process paper such as a polyester film subjected to a release treatment, the heat conductive pressure-sensitive adhesive composition (E) or The solidified product is sandwiched between two exfoliated process papers if necessary and passed between rolls, and the thickness is controlled through a die during extrusion using an extruder, etc. Is mentioned.

  While forming into a sheet or after forming into a sheet, for example, the heat conductive pressure-sensitive adhesive composition (E) is suitably obtained by heating the heat conductive pressure-sensitive adhesive composition (E) with hot air, an electric heater, infrared rays, or the like. be able to. The heating temperature at this time is preferably such that the organic peroxide thermal polymerization initiator decomposes efficiently and the polymerization of the (meth) acrylic acid ester monomer (α1) proceeds. Although a temperature range changes with kinds of organic peroxide thermal-polymerization initiator to be used, 100 to 200 degreeC is preferable and 130 to 180 degreeC is more preferable.

  The heat conductive pressure-sensitive adhesive sheet (F) is obtained by forming the heat conductive pressure-sensitive adhesive composition (E) into a sheet shape and heating it to a temperature of 100 ° C. or higher and 200 ° C. or lower. It is a sheet-like molded article obtained by forming a sheet of the pressure-sensitive adhesive composition (E) and polymerizing the (meth) acrylic acid ester monomer (α1) in the heat conductive pressure-sensitive adhesive composition (E). It is preferable.

3. Electronic component The above-mentioned heat conductive pressure-sensitive adhesive sheet (F) of the present invention can be used as a part of an electronic component. At that time, it can be directly molded on a base material such as a radiator and provided as a part of the electronic component. Specific examples of the electronic component include components around a heat generating part in a device having an electroluminescence (EL) light emitting diode (LED) light source, components around a power device such as an automobile, a fuel cell, a solar cell, a battery, and a mobile phone. And devices and parts having a heat generating part such as a personal digital assistant (PDA), a notebook computer, a liquid crystal, a surface conduction electron-emitting device display (SED), a plasma display panel (PDP), or an integrated circuit (IC). .

  In addition, as an example of the usage method for the electronic device of the heat conductive pressure-sensitive adhesive sheet (F) of the present invention, an LED light source can be used in a specific manner as described below. That is, it is directly attached to the LED light source; sandwiched between the LED light source and a heat dissipation material (heat sink, fan, Peltier element, heat pipe, graphite sheet, etc.); , Heat pipe, graphite sheet, etc.); used as a casing surrounding the LED light source; affixed to the casing surrounding the LED light source; and filling a gap between the LED light source and the casing. Application examples of LED light sources include backlight devices for display devices having a transmissive liquid crystal panel (TVs, mobile phones, PCs, notebook PCs, PDAs, etc.); vehicle lamps; industrial lighting; commercial lighting; Lighting; and the like.

  Specific examples other than the LED light source include the following. That is, PDP panel; IC heating part; Cold cathode tube (CCFL); Organic EL light source; Inorganic EL light source; High luminance light emitting LED light source; High luminance light emitting organic EL light source; And so on.

  Furthermore, as a usage method of the heat conductive pressure-sensitive-adhesive sheet (F) of this invention, affixing on the housing | casing of an apparatus etc. can be mentioned. For example, in an apparatus used for an automobile or the like, it is attached to the inside of a casing provided in the automobile; it is attached to the exterior of the casing provided in the automobile; a heat generating part (car navigation / A fuel cell / heat exchanger) and the casing; and affixing to a heat sink connected to a heat generating part (car navigation / fuel cell / heat exchanger) in the casing of the automobile; Can be mentioned.

  In addition to a motor vehicle, the heat conductive pressure-sensitive-adhesive sheet (F) of this invention can be used by the same method. For example, a personal computer; a house; a TV; a mobile phone; a vending machine; a refrigerator; a solar cell; a surface conduction electron-emitting device display (SED); an organic EL display; an inorganic EL display; Notebook PCs; PDAs; fuel cells; semiconductor devices; rice cookers; washing machines; washing dryers; optical semiconductor devices combining optical semiconductor elements and phosphors; various power devices;

  Furthermore, the heat conductive pressure-sensitive adhesive sheet (F) of the present invention is not limited to the above method of use, and can be used according to applications. For example, used for heat equalization of carpets and warm mats; used as LED light source / heat source sealant; used as solar cell sealant; used as solar cell backsheet Used between the backsheet of the solar cell and the roof; used inside the heat insulating layer inside the vending machine; used inside the housing of the organic EL lighting with a desiccant and a hygroscopic agent; organic EL lighting Use with desiccant and hygroscopic agent on the heat conductive layer inside the housing of the LED; Use with desiccant and hygroscopic agent on the heat conductive layer and heat dissipation layer inside the housing of the organic EL lighting Used for heat conduction layer inside the housing of organic EL lighting, epoxy heat dissipation layer, and on top of it with desiccant and hygroscopic agent; cooling equipment, clothing, towels, sheets, etc. for cooling humans and animals On the opposite side of the body to the member Used for pressure members of fixing devices mounted on image forming apparatuses such as electrophotographic copying machines and electrophotographic printers; Pressurizing fixing devices mounted on image forming apparatuses such as electrophotographic copying machines and electrophotographic printers Used as a member itself; used as a heat flow control heat transfer part for placing a treatment object of a membrane control device; used as a heat flow control heat transfer part for placing a treatment object of a film control device; outer layer of a radioactive substance storage container It can be used between the interior and interior; used in a box body with a solar panel that absorbs sunlight; used between the reflective sheet of the CCFL backlight and the aluminum chassis.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the examples. The “parts” and “%” used here are based on mass unless otherwise specified.

<Thickness>
The thickness of the heat conductive pressure sensitive adhesive sheet was measured. The thickness of a polyethylene terephthalate film with a release agent (hereinafter referred to as “release PET”) was corrected to zero and placed on a thickness measuring instrument with the release PET attached thereto, and the thickness was measured. The results are shown in Tables 2-5.

<Thermal conductivity>
A test piece was prepared by cutting a thermally conductive pressure-sensitive adhesive sheet into a size of 50 mm width × 110 mm length with scissors. The release PET of this test piece was peeled off, and a wrap film was affixed to the surface where the release PET was peeled off so as not to enter air. The size of the wrap film may be larger than the adhesive surface of the test piece. And the heat conductivity was measured using the test piece which stuck this wrap film. The thermal conductivity (unit: W / m · K) was measured by a non-stationary hot wire comparison method using a rapid thermal conductivity meter (trade name “QTM-500”, manufactured by Kyoto Electronics Industry Co., Ltd.). For the reference plate, silicon sponge (current value: 1A), silicone rubber (current value: 2A), and quartz (current value: 4A) were used in this order. The results are shown in Tables 2-5. If the result of this evaluation is greater than 1.0 W / m · K, it can be said that the thermal conductivity is excellent.

<Burning time>
Five test pieces were prepared by cutting the thermally conductive pressure-sensitive adhesive sheet into a size of width 10 mm × length 150 mm. A Bunsen burner air and gas flow rate was adjusted to produce a blue flame of about 20 mm in height, and a burner flame was applied to the lower end of a vertically supported specimen (so that it crossed the flame about 10 mm) and held for 10 seconds. After that, the test piece and the burner flame were released. Thereafter, as soon as the flame of the test piece disappeared, the burner flame was applied to the test piece and held for another 10 seconds, and then the test piece and the burner flame were separated. The flaming and non-flaming combustion durations after the first and second flame contact and the presence or absence of combustion drops (drip) were evaluated. The results are shown in Tables 2-5. In Tables 2 to 5, the numbers written in the column of the burning time indicate the total time of the flaming and non-flamming burning times of the five test pieces.
<Flame retardance>
UL-94 (flame retardant standard) was determined by the above burning time test. That is, the flaming combustion duration after the end of the first and second flame contact, the total of the flammable combustion duration and the flameless combustion duration after the end of the second flame contact, Whether it corresponds to V-0, V-1, or V-2 was determined based on the total flameless combustion time and the presence or absence of combustion drops (drip). In both the first and second times, the flammable combustion was completed within 10 seconds, and the total of the second flammable combustion duration and the flameless combustion time was within 30 seconds. The total flame burning time was within 50 seconds, and there was no burning fallen thing as V-0. In addition, the first and second flames were burned within 30 seconds, and the total of the second flame burning time and the flameless burning time was within 60 seconds, and another 5 flames were burned. And the flameless combustion time was within 250 seconds, and V-2 was defined as the one that had combustion fallen objects. Furthermore, all burned items were out of specification. The results are shown in Tables 2-5. If this evaluation satisfies the V-0 condition, it can be said that the flame retardancy is excellent.

<Volume resistivity>
A test piece was prepared by cutting a thermally conductive pressure-sensitive adhesive sheet into a size of 80 mm × 80 mm. A test piece was set on a digital ultra-high resistance / micro current resistance meter (trade name “8340A”, manufactured by ADC Co., Ltd.), and current was passed through both right and left sides of the test piece to measure resistivity. The voltage started from 500 V and gradually decreased to a measurable voltage, and the resistivity at the measurable voltage was measured. The charging time was 1 minute. The measurement was performed three times, and the average value was defined as the volume resistivity (unit: Ω · cm) of the heat conductive pressure-sensitive adhesive sheet. The results are shown in Tables 2-5. If the result of this evaluation is 1.0 × 10 ⁸ Ω · cm or more, it can be said to be non-conductive.

<Hardness>
A plurality of test pieces were prepared by cutting the heat conductive pressure sensitive adhesive sheet into a size of 30 mm × 50 mm. The release PET was peeled off from these test pieces, the surface was pulverized using talc, and a sample was prepared so as to have a thickness of about 6 mm. The sample was placed on a sample table of a hardness meter (trade name “CL-150”, manufactured by Kobunshi Keiki Co., Ltd.), and the damper was dropped to measure the hardness. A value 20 seconds after the damper contacted the sample was read as a measured value. The measurement was performed in a 23 ° C. atmosphere. The results are shown in Tables 2-5. If the result of this evaluation is less than 25, it can be said that the flexibility is excellent.

Example 1
A reactor was charged with 100 parts of a monomer mixture composed of 94% 2-ethylhexyl acrylate and 6% acrylic acid, 0.03 parts 2,2′-azobisisobutyronitrile and 700 parts ethyl acetate. Then, after substitution with nitrogen, a polymerization reaction was carried out at 80 ° C. for 6 hours. The polymerization conversion rate was 97%. The obtained polymer was dried under reduced pressure to evaporate ethyl acetate to obtain a viscous solid (meth) acrylic acid ester polymer (AP1-1). The weight average molecular weight (Mw) of the (meth) acrylic acid ester polymer (AP1-1) was 270,000, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 3.1. The weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined in terms of standard polystyrene by gel permeation chromatography using tetrahydrofuran as an eluent.

  Next, using an electronic balance, 0.5 part of a polyfunctional monomer obtained by mixing pentaerythritol triacrylate, pentaerythritol tetraacrylate and pentaerythritol diacrylate in a ratio of 60: 35: 5, 2-ethylhexyl acrylate (Hereinafter abbreviated as “2EHA”) 38 parts, methacrylic acid (hereinafter abbreviated as “MAA”) 3.4 parts, 1,6-bis (t- Butylperoxycarbonyloxy) hexane (hereinafter abbreviated as “tBCH”) [1 minute half-life temperature is 150 ° C. ] Weighed and mixed in the order of 0.6 part to obtain a liquid raw material.

Next, 58 parts of the (meth) acrylic acid ester polymer (AP1-1) and expanded graphite powder (B-1) (trade name “EC-50”, manufactured by Ito Graphite Industries, Ltd., average particle diameter: 250 μm) 14 parts, condensed phosphate ester (C-1) (trade name “CR-741”, manufactured by Daihachi Chemical Industry Co., Ltd., viscosity: 32000 mPa · s (25 ° C.), 15-100 under atmospheric pressure 48 parts of a liquid always in the temperature range of 0 ° C., 48 parts of the compound name “bisphenol A bis (diphenyl phosphate)” and a foaming agent (H-2) (trade name “Neoselbon N # 1000S”, manufactured by Eiwa Chemical Industry Co., Ltd.) 19 parts, 288 parts of flammable heat conductive inorganic compound (D-1) (aluminum hydroxide, trade name “BF083”, manufactured by Nippon Light Metal Co., Ltd., average particle size: 8 μm), and the liquid raw material are listed. Hobart in order It was charged into a vessel and degassed with stirring mixture under reduced pressure, to give heat-conductive and pressure-sensitive adhesive composition (E-1). The mixing was performed according to the following conditions using a Hobart mixer (trade name “ACM-5LVT type, capacity: 5 L”) manufactured by Kodaira Seisakusho.
Mixing conditions:
Using a thermostatic bath (trade name “Viscomate 150III”, manufactured by Toki Sangyo Co., Ltd.), the temperature control of the Hobart container was set to 40 ° C.
1. 1. Mix in the rotation speed memory 3 × 10 minutes 2. Mix in the rotation speed memory 5 × 10 minutes Rotation speed memory 3 × 10 minutes, mixing while vacuum degassing at -0.1 MPa

  Thereafter, the thermally conductive pressure-sensitive adhesive composition (E-1) is sandwiched between release PET films, formed into a sheet shape with a roll from the release PET film, and polymerized in a hot air oven at 150 ° C. for 20 minutes. To obtain a heat conductive pressure sensitive adhesive sheet (F-1) having a thickness of 1 mm, both surfaces of which were covered with release PET. The polymerization conversion rate of the (meth) acrylic acid ester monomer mixture (α1-1) was calculated from the amount of residual monomers in the heat conductive pressure-sensitive adhesive sheet (F-1), which was 99.9%. It was.

(Examples 2-5, 7-10)
As shown in Table 2 and Table 3, the heat conductive pressure-sensitive adhesive sheets (F-2) to (F-5) and (F) were obtained in the same manner as in Example 1 except that the amount of each compound was changed. -7) to (F-10) were obtained.

(Example 6)
When stirring and mixing in a Hobart container, glass fiber (G) (trade name “chopped strand”, Owens Corning Japan, glass fiber, fiber length: 3 mm) was added, except that 6.8 parts were added. In the same manner as in Example 1, a heat conductive pressure sensitive adhesive sheet (F-6) was obtained.

(Example 11)
Instead of the liquid raw material and the (meth) acrylic acid ester polymer (AP1-1), 90 parts of isoprene homopolymer terminal hydroxyl group-modified liquid product (trade name “PP-IP”, manufactured by Idemitsu Kosan Co., Ltd.) and polyurethane ( A heat conductive pressure-sensitive adhesive sheet (F-11) was obtained in the same manner as in Example 1 except that 10 parts of the trade name “PU-330” (manufactured by Hirono Chemical Co., Ltd.) was used.

(Comparative Examples 1, 3-8)
As shown in Table 4 and Table 5, the heat conductive pressure-sensitive adhesive sheets (FC-1), (FC-3) to (FC-) were the same as in Example 1 except that the amount of each compound was changed. 8) was obtained.

(Comparative Example 2)
When stirring and mixing in a Hobart container, the expanded graphite powder (B) (trade name “EC-50”, manufactured by Ito Graphite Industries Co., Ltd., average particle size: 250 μm) is replaced with 14 parts of flaky graphite (trade name “ A heat conductive pressure-sensitive adhesive sheet (FC-2) was obtained in the same manner as in Example 1 except that 14 parts of “W-5” manufactured by Ito Graphite Industries Co., Ltd., average particle diameter: 5 μm) were used.

(Comparative Example 9)
Example 1 except that 48 parts of glass fiber (G) (trade name “chopped strand”, manufactured by Owens Corning Japan Co., Ltd., glass fiber, fiber length: 3 mm) were added when stirring and mixing in a Hobart container. In the same manner as above, a heat conductive pressure-sensitive adhesive sheet (FC-9) was obtained.

<Performance evaluation>
The evaluation results of the sheets (F-1) to (F-11) prepared in the examples are shown in Tables 2 and 3, and the evaluation results of the sheets (FC-1) to (FC-9) prepared in the comparative examples are shown. The results are shown in Table 4 and Table 5.

  As shown in Table 2 and Table 3, the sheets (F-1) to (F-11) according to the examples are all thermally conductive (thermal conductivity), flame retardant, insulating (volume resistivity), and flexible. Excellent in hardness (hardness). On the other hand, as shown in Tables 4 and 5, any of the above performances of the sheets (FC-1) to (FC-9) according to the comparative examples was inferior. Specifically, the sheet (FC-1) of Comparative Example 1 having a low content of the condensed phosphate ester (C) was inferior in flame retardancy and flexibility. The sheet (FC-2) of Comparative Example 2 using scaly graphite instead of the expanded graphite powder (B) was inferior in thermal conductivity, flame retardancy, and flexibility. The sheet (FC-3) of Comparative Example 3 not containing the foaming agent (H) was inferior in flexibility. The sheet (FC-4) of Comparative Example 4 which does not contain the foaming agent (H) and has a larger content of the expanded graphite powder (B) than Comparative Example 3 was inferior in insulation in addition to flexibility. . The sheet (FC-5) of Comparative Example 5 in which the content of the expanded graphite powder (B) exceeded the range specified in the present invention was inferior in insulation and flexibility. The sheet (FC-6) of Comparative Example 6 in which the content of the expanded graphite powder (B) was below the range specified in the present invention was inferior in thermal conductivity and flame retardancy. The sheet (FC-7) of Comparative Example 7 in which the content of the flame retardant thermally conductive inorganic compound (D) was below the range specified in the present invention was inferior in flame retardancy. The sheet (FC-8) of Comparative Example 8 in which the content of the foaming agent (H) exceeded the range specified in the present invention was inferior in thermal conductivity and flame retardancy. The sheet (FC-9) of Comparative Example 9 in which the content of the glass fiber (G) exceeded the range specified in the present invention was inferior in flexibility.

<Temperature reduction effect when interposed between heat source and heat sink>
A ceramic heater (trade name “MS-5”, 25 mm × 25 mm, manufactured by Sakaguchi Electric Heat Co., Ltd.), a heat conductive pressure-sensitive adhesive sheet, and an aluminum plate (200 mm × 50 mm × thickness 2 mm) are laminated in this order. The heater was connected to the slider and heated at 37V for 90 minutes, and then the maximum temperature on the surface of the ceramic heater was measured. The results are shown in Table 6.

(Example A)
The above measurement was performed using a sheet (F-2 ′) similar to the sheet (F-2) of Example 2 except that the thickness was 1.5 mm. Table 6 shows the thickness, thermal conductivity, and hardness of the sheet (F-2 ′).

(Comparative Example A)
The above measurement was performed using a sheet (FC-4 ′) similar to the sheet (FC-4) of Comparative Example 4. Table 6 shows the thickness, thermal conductivity, and hardness of the sheet (FC-4 ′).

  As shown in Table 6, the sheet (F-2 ') of the present invention had a greater temperature reduction effect than the sheet (FC-4') outside the scope of the present invention.

  Although the present invention has been described in connection with the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein, The heat conductive pressure-sensitive adhesive composition, the heat conductive pressure-sensitive adhesive sheet, and the electronic can be changed as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification. Components should also be understood as being within the scope of the present invention.

Claims (8)

100 parts by mass of at least one polymer (S) selected from the group consisting of rubber, elastomer and resin;
Expanded graphite powder (B) 5 parts by mass or more and 35 parts by mass or less;
7 to 100 parts by mass of the condensed phosphate ester (C),
Flame-retardant thermally conductive inorganic compound (D) 150 parts by weight or more and 500 parts by weight or less,
Foaming agent (H) 0.02 parts by mass or more and 15 parts by mass or less,
The condensed phosphoric ester (C) has a viscosity at 25 ° C. of 7000 mPa · s or more and is always liquid in a temperature range of 15 ° C. or more and 100 ° C. or less under atmospheric pressure ( E). Furthermore, the heat conductive pressure-sensitive-adhesive composition (E) of Claim 1 containing 35 mass parts or less of glass fibers (G). The heat conductive pressure-sensitive-adhesive composition (E) of Claim 1 or 2 whose said polymer (S) is a (meth) acrylic acid ester polymer (A1). The (meth) acrylic acid ester polymer (A1) is obtained by polymerizing the (meth) acrylic acid ester monomer (α1) in the presence of the (meth) acrylic acid ester polymer (AP1). The heat conductive pressure-sensitive-adhesive composition (E) of Claim 3 which exists. The heat conductive pressure sensitive adhesive sheet (F) formed by shape | molding the heat conductive pressure sensitive adhesive composition (E) in any one of Claims 1-4 in a sheet form. While the heat conductive pressure-sensitive adhesive composition (E) according to claim 4 is formed into a sheet or after being formed into a sheet, the (meta) in the heat conductive pressure-sensitive adhesive composition (E) is formed. ) The heat obtained by polymerizing the (meth) acrylate monomer (α1) in the thermally conductive pressure-sensitive adhesive composition (E) in the presence of the acrylate polymer (AP1). A heat conductive pressure-sensitive adhesive sheet (F), which is a solidified sheet-like molded body of the conductive pressure-sensitive adhesive composition (E). The electronic component provided with the heat conductive pressure-sensitive-adhesive sheet (F) of Claim 5 or 6. Equipment with electroluminescence (EL), light emitting diode (LED) light source, automotive power device, fuel cell, solar cell, battery, mobile phone, personal digital assistant (PDA), notebook computer, liquid crystal, surface conduction electron-emitting device The electronic component according to claim 7, wherein the electronic component is a display (SED), a plasma display panel (PDP), or an integrated circuit (IC).