JP5169293B2 - Acrylic resin composition, heat conductive pressure-sensitive adhesive sheet comprising the acrylic resin composition, method for producing the heat conductive pressure-sensitive adhesive sheet, and composite comprising a substrate and the heat conductive pressure-sensitive adhesive sheet - Google Patents

Description

  The present invention includes an acrylic resin composition, a thermally conductive pressure-sensitive adhesive sheet comprising the acrylic resin composition, a method for producing the thermally conductive pressure-sensitive adhesive sheet, and a substrate and the thermally conductive pressure-sensitive adhesive sheet. Relates to the complex.

  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 heat by attaching a heat sink such as a heat sink, a heat radiating metal plate, or a heat radiating fin to a heat generating body such as an electronic component is employed. Various heat conductive sheets are used to efficiently conduct heat from the heating element to the heat radiating body. In general, a heat conductive pressure sensitive adhesive sheet is required for fixing the heat generating element and the heat radiating element. It is said.

As such a heat conductive pressure sensitive adhesive sheet, for example, Patent Document 1 discloses a heat conductive pressure sensitive adhesive composition containing a flame retardant inorganic compound and expanded graphite powder as a main component. Yes. And the heat conductive pressure-sensitive adhesive sheet-like molded body comprising such a heat conductive pressure-sensitive adhesive composition has good flame retardancy, hardness, adhesive properties and thermal conductivity, and is excellent in the balance of these properties. .
WO2007 / 116686 pamphlet

  Like the heat conductive pressure-sensitive adhesive composition disclosed in Patent Document 1, the heat of the heat conductive pressure-sensitive adhesive sheet comprising the heat conductive pressure-sensitive adhesive composition by adding expanded graphite powder. The conductivity could be improved. However, further improvement in thermal conductivity has been desired.

  Accordingly, the present invention relates to a heat conductive pressure-sensitive adhesive sheet having improved thermal conductivity, a method for producing the heat conductive pressure-sensitive adhesive sheet, and an acrylic resin that is the basis of the heat conductive pressure-sensitive adhesive sheet. It is an object to provide a composition.

  As a result of intensive research on the heat conductive pressure-sensitive adhesive sheet, the present inventors have improved the thermal conductivity by molding an acrylic resin composition containing acrylic resins having different weight average molecular weights into a sheet shape. It has been found that a heat conductive pressure sensitive adhesive sheet can be obtained, and the present invention has been completed.

  Thus, according to the first aspect of the present invention, the (meth) acrylic acid ester polymer (A1) having a weight average molecular weight of 100,000 to 500,000 and the (meth) acrylic acid ester having a weight average molecular weight of 1,000 to 5,000. An acrylic resin composition (F) containing a polymer (A2), a (meth) acrylic acid ester monomer (A3m), and an expanded graphite powder (E) is provided.

  In the present invention, “weight average molecular weight” means that measured by gel permeation chromatography (GPC method). Further, “(meth) acrylic acid ester” means acrylic acid ester and / or methacrylic acid ester.

The acrylic resin composition (F) of the first aspect of the present invention preferably further contains aluminum hydroxide .

  In the acrylic resin composition (F) of the first invention, the (meth) acrylic acid ester polymer (A1) preferably contains a monomer unit (a2) having an organic acid group, It is preferable that the acrylate polymer (A2) contains a monomer unit (a3) having a hydroxyl group or an epoxy group.

In the acrylic resin composition (F) of the first invention, the content of the (meth) acrylic acid ester polymer (A1) is such that the (meth) acrylic acid ester polymer (A1) and the (meth) acrylic acid ester weight It is preferable that it is 10 mass%-70 mass% with respect to the total amount with a unification | combination (A2). Furthermore, 100 parts by mass of an acrylic resin mixture comprising 10% by mass to 70% by mass of (meth) acrylic acid ester polymer (A1) and 90% by mass to 30% by mass of (meth) acrylic acid ester polymer (A2), ) Acrylic ester monomer (A3m) 25 parts by mass to 100 parts by mass, expanded graphite powder (E) 10 parts by mass to 100 parts by mass, and aluminum hydroxide 50 parts by mass to 400 parts by mass It is more preferable.

  Moreover, according to 2nd this invention, the heat conductive pressure-sensitive-adhesive sheet (G) formed by heating and shape | molding the acrylic resin composition (F) of said 1st this invention in a sheet form is provided.

  Furthermore, according to 3rd this invention, the acrylic resin composition (F) of said 1st this invention is heated and shape | molded in a sheet form, The heat conductive pressure-sensitive-adhesive sheet (G) characterized by the above-mentioned. A manufacturing method is provided.

  Furthermore, according to 4th this invention, the composite (H) which provides the heat conductive pressure-sensitive-adhesive sheet (G) of said 1st this invention in the single side | surface or both surfaces of a base material is provided.

  According to the present invention, a thermally conductive pressure-sensitive adhesive sheet with improved thermal conductivity, a method for producing the thermally conductive pressure-sensitive adhesive sheet, and an acrylic resin that is the basis of the thermally conductive pressure-sensitive adhesive sheet A composition can be obtained.

The acrylic resin composition (F) of the present invention comprises (meth) acrylic acid ester polymer (A1), (meth) acrylic acid ester polymer (A2), (meth) acrylic acid ester monomer (A3m), and In addition, the expanded graphite powder (E) as an essential constituent and further added with aluminum hydroxide or the like is polymerized while being formed into a sheet, whereby a heat conductive pressure-sensitive adhesive sheet is obtained. Hereinafter, each component which comprises an acrylic resin composition (F), a heat conductive pressure sensitive adhesive sheet, and the manufacturing method of a heat conductive pressure sensitive adhesive sheet are demonstrated in detail.

1. (Meth) acrylic acid ester polymer (A1)
The (meth) acrylic acid ester polymer (A1) has a weight average molecular weight of 100,000 to 500,000. Other conditions for the (meth) acrylic acid ester polymer (A1) that can be used in the present invention are not particularly limited, but (meth) acrylic that forms a homopolymer having a glass transition temperature of −20 ° C. or lower. It is preferable to contain the acid ester monomer unit (a1) and the monomer unit (a2) having an organic acid group.

  There is no particular limitation on the (meth) acrylate monomer (alm) that gives the (meth) acrylate monomer unit (a1) that forms a homopolymer having a glass transition temperature of −20 ° C. or less. 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 (the same − 22 ° C), heptyl acrylate (-60 ° C), hexyl acrylate (-61 ° C), octyl acrylate (-65 ° C), 2-ethylhexyl acrylate (-50 ° C), acrylic acid 2- Methoxyethyl (-50 ° C), 3-methoxypropyl acrylate (-75 ° C), 3-methoxybutyl acrylate (-56 ° C), 2-ethoxymethyl acrylate (-50 ° C) , Octyl methacrylate (same -25 ° C.), and the like decyl methacrylate (same -49 ° C.).

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

  In these (meth) acrylic acid ester monomers (alm), the monomer unit (a1) derived therefrom is preferably 80% by mass to 99.9% by mass in the (meth) acrylic acid ester polymer (A1). %, More preferably 85 to 99.5% by weight. When the amount of the (meth) acrylic acid ester monomer (alm) is within the above range, the heat-sensitive pressure-sensitive adhesive sheet (G) obtained from this 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, 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 used. 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 an organic acid group, the monomer unit (a2) derived therefrom is 20% by mass to 0.1% by mass in the (meth) acrylic acid ester polymer (A1), preferably 15%. It is desirable to be used for the polymerization in such an amount that the mass% is 0.5% by mass. 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) acrylic acid ester 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 (A1) 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) acrylate polymer (A1). 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 (A1) is a unit of (meth) acrylic acid ester monomer (a1) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, and an organic acid group. 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 (meth) acrylic acid ester polymer (A1).

  The monomer (a4m) is not particularly limited, and as a specific example thereof, a (meth) acrylic acid ester monomer (alm) other than (meth) acrylate monomer (alm) that forms 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 (meth) acrylate monomers other than (meth) acrylate monomers (alm) that form homopolymers 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 α, β-ethylenically unsaturated polyvalent carboxylic acid complete esters such as methyl itaconate, butyl maleate and propyl fumarate include dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, itacon Examples include dimethyl acid.

  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-dibutadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro- Examples thereof include 1,3-butadiene and cyclopentadiene.

  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 (meth) acrylic acid ester polymer (A1) is a (meth) acrylic acid ester monomer (a1m) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, a monomer having an organic acid group (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 polymerization initiation method is not particularly limited, but it is preferable to use a thermal polymerization initiator as the polymerization initiator (C1). 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 azo compound polymerization initiators, 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 (C1) is not specifically limited, It is preferable that it is the range of 0.01-50 mass parts 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, but in the case of solution polymerization, the (meth) acrylic acid ester polymer (A1) 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 (A1) can be controlled by appropriately adjusting the amount of the polymerization initiator used in the polymerization and the amount of the chain transfer agent.

2. (Meth) acrylic acid ester polymer (A2)
The (meth) acrylic acid ester polymer (A2) has a weight average molecular weight of 1000 or more and 5000 or less.

  Although it does not specifically limit as other conditions of the (meth) acrylic acid ester polymer (A2) which can be used for this invention, Glass transition temperature similarly to the (meth) acrylic acid ester polymer (A1) mentioned above. A (meth) acrylic acid ester monomer (a1m) that forms a homopolymer having a temperature of −20 ° C. or lower, a monomer having an organic acid group (a2m), and a monomer containing a functional group other than an organic acid group It is particularly preferred by copolymerizing the monomer (a3m) and one or more monomers selected from the group consisting of monomers (a4m) copolymerizable with these monomers. Can be obtained. In addition, the method of superposition | polymerization is not specifically limited, The method similar to the (meth) acrylic acid ester polymer (A1) mentioned above can be used. However, the (meth) acrylic acid ester polymer (A2) is a single monomer having a functional group that has good reactivity with respect to the functional group of the monomer unit contained in the (meth) acrylic acid ester polymer (A1). It is preferable to contain a monomer unit. For example, when the (meth) acrylic acid ester polymer (A1) contains a monomer unit having a carboxyl group, the (meth) acrylic acid ester polymer (A2) is a hydroxyl group, an epoxy group or the like. It preferably contains a monomer unit having a functional group.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A2) can be controlled by appropriately adjusting the amount of the polymerization initiator used in the polymerization and the amount of the chain transfer agent.

  In the acrylic resin composition (F) of the present invention, the (meth) acrylic acid ester polymer with respect to the total amount of the (meth) acrylic acid ester polymer (A1) and the (meth) acrylic acid ester polymer (A2). The content of (A1) is preferably 10% by mass to 70% by mass, and the content of the (meth) acrylic acid ester polymer (A2) is preferably 90% by mass to 30% by mass.

  In the present invention, the acrylic resin mixture comprising the (meth) acrylic acid ester polymer (A1) and the (meth) acrylic acid ester polymer (A2) may be hereinafter referred to as “acrylic resin mixture (S)”. The acrylic resin mixture (S) is composed of 10% by mass to 70% by mass of the (meth) acrylic acid ester polymer (A1) and 90% by mass to 30% by mass of the (meth) acrylic acid ester polymer (A2). Preferably, (meth) acrylic acid ester polymer (A1) 20% by mass to 60% by mass and (meth) acrylic acid ester polymer (A2) 80% by mass to 40% by mass are more preferable. In the said acrylic resin mixture (S), when content of (meth) acrylic acid ester polymer (A1) and (meth) acrylic acid ester polymer (A2) exists in the said preferable range, heat conductive pressure sensitivity It is excellent in moldability when the adhesive composition (F) is made into a heat conductive pressure-sensitive adhesive sheet (G), and excellent in the heat conductivity of the resulting heat conductive pressure-sensitive adhesive sheet (G).

3. (Meth) acrylic acid ester monomer (A3m)
The heat conductive pressure sensitive adhesive composition (F) of the present invention contains a (meth) acrylic acid ester monomer (A3m), and the heat conductive pressure sensitive adhesive composition (F) is formed into a sheet shape. When the heat conductive pressure-sensitive adhesive sheet (G) is obtained, the (meth) acrylate monomer (A3m) is polymerized and converted to a (meth) acrylate polymer.

  The (meth) acrylic acid ester monomer (A3m) is not particularly limited as long as it is a (meth) acrylic acid ester monomer, but forms a homopolymer having a glass transition temperature of −20 ° C. or lower (meta ) Acrylic acid ester monomer (a5m) is preferred.

  Examples of the (meth) acrylic acid ester monomer (a5m) forming a homopolymer having a glass transition temperature of −20 ° C. or lower are exemplified as the (meth) acrylic acid ester monomer (alm) described above. (Meth) acrylic acid ester monomers similar to those mentioned above 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.

  Further, the (meth) acrylate monomer (A3m) may be used as a mixture (A3m ′) of the (meth) acrylate monomer (a5m) and a monomer copolymerizable therewith. Good.

  Particularly preferred (meth) acrylate monomer mixture (A3m ′) is a (meth) acrylate monomer (a5m) that forms a homopolymer having a glass transition temperature of −20 ° C. or less, and organic It is a monomer mixture (A3m ′) composed of a monomer (a6m) having an acid group.

  Examples of the monomer having an organic acid group (a6m) include the same monomers having an organic acid group as exemplified as the monomer (a2m) described above. 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 (meth) acrylic acid ester monomer (a5m) in the (meth) acrylic acid ester monomer mixture (A3m ′) is preferably 70% by mass to 99.9% by mass, more preferably 75% by mass. It is -99 mass%. When the ratio of the (meth) acrylic acid ester monomer (a5m) is in the above range, the pressure-sensitive adhesiveness and flexibility of the heat conductive pressure-sensitive adhesive sheet (G) are excellent.

  The ratio of the monomer (a6m) having an organic acid group in the (meth) acrylic acid ester monomer mixture (A3m ′) is preferably 30% by mass to 0.1% by mass, and more preferably 25% by mass to 1% by mass. When the ratio of the monomer having an organic acid group (a6m) is in the above range, the hardness of the heat conductive pressure sensitive adhesive sheet is appropriate, and the pressure sensitive adhesive property at high temperature (100 ° C.) is good. It becomes.

  (Meth) acrylic acid ester monomer mixture (A3m ′) is copolymerized with (meth) acrylic acid ester monomer (a5m) and monomer having organic acid group (a6m). A possible monomer (a7m) can be contained in the range of 20.0% by mass or less.

  As an example of the monomer (a7m), in addition to the monomer (a3m) and the monomer (a4m) described above, the same monomers as exemplified as the polyfunctional monomer shown below 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.

  As polyfunctional monomers, 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, pen erythritol 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, pen erythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol tetra (meth) acrylate are preferable.

  The (meth) acrylic acid ester monomer (A3m) preferably contains the above polyfunctional monomer. The polyfunctional monomer is preferably contained in an amount of 0.5% by mass to 5% by mass, more preferably 1% by mass to 3% by mass with respect to 100 parts by mass of the (meth) acrylic acid ester monomer (A3m). It is desirable to do.

  The amount of the (meth) acrylic acid ester monomer (A3m) is usually 25 parts by mass to 100 parts by mass, preferably 30 parts by mass to 70 parts by mass with respect to 100 parts by mass of the acrylic resin mixture (S). . If the amount of the (meth) acrylic acid ester monomer (A3m) is less than the lower limit or exceeds the upper limit of the above range, the heat-sensitive pressure-sensitive adhesive sheet (G) may be inferior in pressure-sensitive adhesion retention.

4). Expanded graphite powder (E)
As an example of the expanded graphite powder (E) 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 expanded graphite powder (E) used in the present invention preferably has a plurality of peaks in the particle size distribution. In order to have a plurality of peaks in the particle size distribution of the expanded graphite powder (E), the particle sizes are aligned so that each particle size distribution has one peak. It is preferable to prepare expanded graphite powder and mix them to obtain expanded graphite powder (E).

  The average particle size and particle size distribution of the expanded graphite powder are measured by the measurement method described below.

(Measuring method of average particle size and particle size distribution of expanded graphite powder)
Using a laser type particle size measuring machine (manufactured by Seishin Enterprise Co., Ltd.), measurement is performed by a micro-sorting control method (a method in which the measurement target particles are allowed to pass only in the measurement region and the measurement reliability is improved). When 0.01 to 0.02 g of the expanded graphite powder to be measured flows in the cell, the expanded graphite powder flowing into the measurement region is irradiated with a semiconductor laser beam having a wavelength of 670 nm, and the laser beam at that time Is measured by a measuring machine, the average particle size and particle size distribution are calculated from the Franhofer diffraction principle, and the results are displayed.

  The content of the expanded graphite powder (E) with respect to 100 parts by mass of the acrylic resin mixture (S) is preferably 10 parts by mass to 100 parts by mass, more preferably 30 parts by mass to 80 parts by mass, and even more preferably 40 parts by mass to 70 parts by mass.

  If the content of the expanded graphite powder (E) is less than the lower limit of the above range, the effect of improving the thermal conductivity of the heat conductive pressure-sensitive adhesive sheet (G) is low, whereas, if the content exceeds the upper limit of the above range, During molding, the viscosity of the heat conductive pressure-sensitive adhesive composition (F) increases, and it tends to be impossible to form a sheet or to form a sheet.

5. Aluminum hydroxide The shape of aluminum hydroxide that can be used in the present invention is not particularly limited, and may be any of spherical, needle-like, fibrous, scale-like, dendritic, flat, and indeterminate shapes.

The use of water aluminum oxide, it is possible to impart heat-conductive and pressure-sensitive adhesive composition (F) and excellent flame retardancy thermal conductivity pressure sensitive sheet (G) of the present invention.

  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 (F) is increased, and at the same time, the hardness is increased, and the shape followability of the heat conductive pressure-sensitive adhesive sheet (G) is decreased. There is a risk of causing it. On the other hand, when the average particle size exceeds 80 μm, the surface of the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is roughened, and there is a possibility that the adhesive force is reduced at high temperature or thermally deformed at high temperature. is there.

The content of aluminum hydroxide contained in the heat conductive pressure-sensitive adhesive composition (F) is preferably 50 parts by mass to 400 parts by mass, more preferably 100 parts per 100 parts by mass of the acrylic resin mixture (S). It is mass part -350 mass parts, More preferably, it is 200 mass parts -300 mass parts.

If the content of aluminum hydroxide is less than the lower limit of the above range, there is a problem such as a decrease in the high temperature adhesive force and thermal conductivity of the heat conductive pressure-sensitive adhesive sheet (G), while on the other hand, when the upper limit of the above range is exceeded, The hardness of a heat conductive pressure sensitive adhesive sheet (G) increases, and the problem of a shape followability fall arises.

6). Other components 6.1. Polymerization initiator (C2)
It is preferable to polymerize the (meth) acrylic acid ester monomer (A3m) when forming the heat conductive pressure-sensitive adhesive sheet (G). In order to accelerate the polymerization, the thermally conductive pressure-sensitive adhesive composition (F) comprises (meth) acrylic acid ester polymer (A1), (meth) acrylic acid ester polymer (A2), and (meth) acrylic. In addition to the acid ester monomer (A3m), it is preferable to further contain a polymerization initiator (C2).

  Examples of the polymerization initiator (C2) include organic peroxide thermal polymerization initiators, photopolymerization initiators, azo-based thermal polymerization initiators, and the like. Adhesive strength of the resulting heat conductive pressure-sensitive adhesive sheet (G) From the viewpoint of the above, an organic peroxide thermal polymerization initiator is preferably used.

  Examples of organic peroxide thermal polymerization initiators include hydroperoxides 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 the organic peroxide thermal polymerization initiators, those having a one-minute half-life temperature of 120 ° C. or more and 170 ° C. or less are preferable.

  The amount of the organic peroxide thermal polymerization initiator used is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the acrylic resin mixture (S). More preferably, it is 0.5 to 2 parts by mass.

  The polymerization conversion rate of the (meth) acrylic acid ester monomer (A3m) 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 (G), which is not preferable.

6.2. Thermally decomposable organic foaming agent (D)
A foaming agent can also be added to the heat conductive pressure sensitive adhesive composition (F) of the present invention in order to foam the heat conductive pressure sensitive adhesive sheet (G) obtained therefrom. As the foaming agent, a thermally decomposable organic foaming agent (D) is preferable. Furthermore, as a thermally decomposable organic foaming agent (D), what has a decomposition | disassembly start temperature of 80 degreeC or more and 200 degrees C or less is preferable.

  Specific examples of such a thermally decomposable organic foaming agent (D) include 4,4'-oxybis (benzenesulfonylhydrazide). A foaming system in which a certain amount of a foaming assistant described later is mixed with an organic foaming agent having a thermal decomposition start temperature higher than 200 ° C. such as azodicarboxamide, and the thermal decomposition start temperature is 100 ° C. or higher and 200 ° C. or lower is also heated. The degradable organic foaming agent (D) can be used.

  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.

6.3. External cross-linking agent An external cross-linking agent is added to the heat-conductive pressure-sensitive adhesive composition (F) of the present invention in order to increase the cohesive force as a pressure-sensitive adhesive and to improve heat resistance. ) A crosslinked structure is introduced into a polymer obtained by polymerizing the (meth) acrylate monomer (A3m) in the presence of the acrylate polymer (A1) and the (meth) acrylate polymer (A2). be able to.

  External crosslinking agents include polyfunctional isocyanate-based crosslinking agents such as tolylene diisocyanate, trimethylolpropane diisocyanate, and diphenylmethane triisocyanate, and epoxy crosslinking agents such as diglycidyl ether, polyethylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether. And melamine resin crosslinking agent, amino resin crosslinking agent, metal salt crosslinking agent, metal chelate crosslinking agent, peroxide crosslinking agent, and the like.

  The external cross-linking agent is a polymer obtained by polymerizing the (meth) acrylic acid ester monomer (A3m) in the presence of the (meth) acrylic acid ester polymer (A1) and the (meth) acrylic acid ester polymer (A2). After the coalescence is obtained, it is added to this and subjected to heat treatment or radiation irradiation treatment to form crosslinks within and / or between the molecules of the copolymer.

6.4. Other components The heat conductive pressure-sensitive adhesive composition (F) of the present invention may further contain various known additives such as pigments, other fillers, flame retardants, anti-aging agents, and thickeners, if necessary. In the range which does not impair the effect of this invention, it can contain.

  As a pigment, it can be used regardless of organic type and inorganic type, such as carbon black other than expanded graphite powder (E), and titanium dioxide. Examples of other fillers include inorganic compounds such as clay. You may add nanoparticles, such as fullerene and a carbon nanotube. Examples of the flame retardant include ammonium polyphosphate, zinc borate, tin compound, organic phosphorus compound, red phosphorus compound, and silicone flame retardant. 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.

7). Thermally conductive pressure-sensitive adhesive sheet (G) and production method thereof The thermally conductive and pressure-sensitive adhesive sheet (G) of the present invention is formed by heating and molding a thermally conductive and pressure-sensitive adhesive composition (F). .

  Although the thickness of the heat conductive pressure sensitive adhesive sheet (G) of this invention is not specifically limited, Usually, they are 50 micrometers-3 mm. If it is thinner than 50 μm, air is likely to be involved when affixing to the heat generator and the heat radiating body, and as a result, sufficient thermal conductivity may not be obtained. On the other hand, if it is thicker than 3 mm, the thermal resistance in the thickness direction of the heat conductive pressure-sensitive adhesive sheet (G) is increased, and there is a possibility that the heat dissipation is impaired.

  The method for forming the heat conductive pressure-sensitive adhesive composition (F) into a sheet is not particularly limited. Suitable methods include, for example, a casting method in which the heat conductive pressure-sensitive adhesive composition (F) is applied onto process paper such as a polyester film subjected to a release treatment, and a heat conductive pressure-sensitive adhesive composition (F). Examples of the method include a method of passing between rolls by interleaving between two exfoliated process papers if necessary, and a method of controlling the thickness through a die when extruding using an extruder.

  In forming the sheet, it is desirable to apply pressure in order to make the thickness uniform. The pressure condition is usually 10 MPa or less, preferably 1 MPa or less. Pressurization exceeding 10 MPa is not preferable because the foamed cell may be crushed when the thermally conductive pressure-sensitive adhesive sheet (G) is foamed. The pressurization time may be selected in accordance with the temperature conditions and the type and amount of the polymerization initiator to be used, but is preferably within 1 hour in view of productivity.

  While forming into a sheet or after forming into a sheet, for example, the heat conductive pressure-sensitive adhesive composition (F) can be obtained by heating the heat conductive pressure-sensitive adhesive composition (F) with hot air, an electric heater, infrared rays, or the like. it can. The heating temperature at this time is preferably such that the organic peroxide thermal polymerization initiator (C2) decomposes efficiently and the polymerization of the (meth) acrylate monomer (A3m) proceeds. Although a temperature range changes with kinds of organic peroxide thermal-polymerization initiator (C2) to be used, 100 to 200 degreeC is preferable.

  The heat conductive pressure sensitive adhesive sheet (G) is obtained by forming the heat conductive pressure sensitive adhesive composition (F) into a sheet shape and heating it to a temperature of 100 ° C. or higher and 200 ° C. or lower. It is preferable that it is a sheet-like molded object formed by forming the pressure-adhesive composition (F) into a sheet and polymerizing the (meth) acrylic acid ester monomer (A3m). Foaming may be performed, but an unfoamed material is preferred because it is more excellent in thermal conductivity.

8). Complex (H)
The composite (H) of the present invention is obtained by providing a heat conductive pressure-sensitive adhesive sheet (G) on one side or both sides of a substrate.

  In the composite (H) of the present invention, when the layer of the heat conductive pressure-sensitive adhesive sheet (G) is formed on one surface or both surfaces of the substrate, the substrate 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 composite (H) of the present invention can also be provided as a part of an electronic component by directly forming a heat conductive pressure-sensitive adhesive sheet (G) on a base material such as a radiator.

  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.

(Thermal conductivity of heat conductive pressure sensitive adhesive sheet)
A heat conductive pressure-sensitive adhesive sheet was cut into a size of 50 mm width × 110 mm length × 1 mm thickness, and allowed to stand in a thermostatic chamber at 23 ° C. for 48 hours or more to prepare a sample. The thermal conductivity (unit: W / m · K) was measured by a non-stationary hot wire comparison method using a rapid thermal conductivity meter (QTM-500: manufactured by Kyoto Electronics Industry Co., Ltd.). As comparative standard plates with known thermal conductivity, silicon sponge (0.1 W / m · K), silicon rubber (0.2 W / m · K), quartz (1.4 W / m · K), zirconia ( 3.4 W / m · K) and mullite (5.7 W / m · K) were used. “-” Shown in Table 2 means that the test was not performed because the heat conductive pressure-sensitive adhesive sheet could not be prepared.

(Holding power of heat conductive pressure sensitive adhesive sheet)
An aluminum plate is pressure-bonded to one surface of a test piece having a width of 30 mm, a length of 30 mm, and a thickness of 1 mm so that air does not enter between the surfaces, and air is not inserted between the other surfaces of the test piece. The laminated body which pressure-bonded the glass plate was produced. The aluminum plate was marked so that the initial position of the test piece was known. Next, the laminate was placed on the floor with the aluminum plate facing down, and a 1 kg weight was placed so as to be directly above the test piece through the glass plate. This state was maintained for 8 minutes. Thereafter, the laminated body was placed in a constant temperature layer at 80 ° C. in a state where it was raised 90 degrees. In this state, whether or not the state of the heat conductive pressure-sensitive adhesive sheet was retained was determined based on whether or not the state could be retained after 60 minutes. “◯” shown in Table 2 means that the state was maintained after 60 minutes. On the other hand, “-” means that the test was not performed because the heat conductive pressure-sensitive adhesive sheet could not be prepared.

Example 1
<Creation of heat conductive pressure sensitive adhesive composition>
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 (A1) (1). The weight average molecular weight (Mw) of the (meth) acrylic acid ester polymer (A1) (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, 1 part of a cross-linking agent prepared by mixing pentaerythritol triacrylate, pentaerythritol tetraacrylate, and pentaerythritol diacrylate in a ratio of about 60: 35: 5, 2-ethylhexyl acrylate (hereinafter, 60 parts of methacrylic acid (hereinafter abbreviated as “MAA”), 1,6-bis (t-butylperoxy) which is an organic peroxide thermal polymerization initiator (C2) Carbonyloxy) hexane (hereinafter abbreviated as “tBCH”) [1 minute half-life temperature is 150 ° C. ] 1.8 parts were weighed and mixed to obtain a liquid raw material.

Next, 20 parts of (meth) acrylate polymer (A1) (1), UG-4010 (epoxy group-containing solventless acrylic resin, weight average molecular weight) which is (meth) acrylate polymer (A2) : 2900, 80 parts by Toa synthetic Ltd.), 200 parts of water of aluminum oxide, the breakdown of (60 parts of E) (expanded graphite powder (E) expanded graphite powder, EC-50 (average particle diameter: Stainless steel container (Hobart) in the order listed: 250 μm, 30 parts by Ito Graphite Industries Co., Ltd., EC-500 (average particle size: 30 μm, 30 parts by Ito Graphite Industries Co., Ltd.) Container).

  Each of the above raw materials placed in a Hobart container was stirred at 40 ° C. for 30 minutes, then evacuated and further stirred for 10 minutes to obtain a viscous liquid heat conductive pressure-sensitive adhesive composition (F) (1).

<Creation of heat conductive pressure sensitive adhesive sheet>
A method for preparing a heat conductive pressure-sensitive adhesive sheet will be described with reference to FIG. FIG. 1 is a diagram schematically showing a part of a heat conductive pressure-sensitive adhesive sheet manufacturing process. Fig.1 (a) is the figure which looked at each member used for preparation of a heat conductive pressure-sensitive-adhesive sheet from the top. FIGS. 1B to 1D are views showing a cross section taken along a broken line shown in FIG.

  A flat plate 1 made of aluminum (hereinafter referred to as “aluminum plate 1”) and a thickness adjusting frame 2 (hereinafter referred to as “frame 2”) are prepared. As shown in FIG. A frame 2 was placed on the aluminum plate 1 placed on the top. The frame 2 has a space of 297 mm long × 210 mm wide × 1 mm high inside. Next, as shown in FIG.1 (b), the film 3 made from a polyethylene terephthalate is put on the frame 2, and also a heat conductive pressure sensitive adhesive composition (F) (1) 4 (henceforth " An appropriate amount of “Composition 4” was added. Next, as shown in FIG.1 (c), as shown in FIG.1 (d), the film 5 made from a polyethylene terephthalate is put on the composition 4, and it presses strongly with a roll from the top of the film 5, as shown in FIG.1 (c). The composition 4 was formed to a size that fits inside the frame 2. Next, the composition 4 was sandwiched between the film 3 and the film 5 and sandwiched between aluminum plates that had been previously placed in an oven at 150 ° C., and returned to the oven. After 20 minutes, the sheet was taken out from the oven to obtain a heat conductive pressure-sensitive adhesive sheet according to Example 1.

(Example 2, Example 3, Comparative Example 1, and Comparative Example 2)
Implementation was carried out in the same manner as in Example 1 except that the content of the (meth) acrylic acid ester polymer (A1) (1) and the type and content of the (meth) acrylic acid ester polymer (A2) were changed. The heat conductive pressure-sensitive-adhesive sheet concerning Example 2, Example 3, the comparative example 1, and the comparative example 2 was obtained.

  Specifically, in Example 2, the content of the (meth) acrylic acid ester polymer (A1) (1) is 25 parts, and UH-2000 (hydroxyl group-containing) is used as the (meth) acrylic acid ester polymer (A2). 75 parts of a solventless acrylic resin, weight average molecular weight: 2000, manufactured by Toagosei Co., Ltd.

  In Example 3, the content of the (meth) acrylic acid ester polymer (A1) (1) was 60 parts, and 40 parts of UH-2000 was used as the (meth) acrylic acid ester polymer (A2).

  In Comparative Example 1, the content of the (meth) acrylic acid ester polymer (A1) (1) was 100 parts, and the (meth) acrylic acid ester polymer (A2) was not used.

  In Comparative Example 2, (meth) acrylic acid ester polymer (A1) (1) was not used, and 100 parts of UH-2000 was used as (meth) acrylic acid ester polymer (A2).

(Comparative Example 3)
A heat conductive pressure-sensitive adhesive sheet according to Comparative Example 3 was obtained in the same manner as Example 3 except that the expanded graphite powder (E) was not used.

(Comparative Example 4)
A heat conductive pressure-sensitive adhesive sheet according to Comparative Example 4 was obtained in the same manner as Comparative Example 1 except that the expanded graphite powder (E) was not used.

  Table 1 shows the compositions of the thermally conductive pressure-sensitive adhesive compositions prepared in the examples and comparative examples.

<Performance evaluation of heat conductive pressure sensitive adhesive sheet>
The heat conductive pressure sensitive adhesive sheet produced above was evaluated according to the following criteria. The results are shown in Table 2.

From the above results, the heat conductive pressure-sensitive adhesive sheets (Examples 1 to 3) made of an acrylic resin composition containing two kinds of acrylic resins having different weight average molecular weights and expanded graphite powder have high thermal conductivity. I understand that. On the other hand, in the heat conductive pressure-sensitive adhesive sheet (Comparative Example 1) prepared using only an acrylic resin having a high weight average molecular weight and not using an acrylic resin having a low weight average molecular weight as the acrylic resin, Examples 1 to Examples Compared with the heat conductive pressure-sensitive adhesive sheet of No. 3, the thermal conductivity was low. In addition, as the acrylic resin, only the acrylic resin having a low weight average molecular weight is used, and the heat conductive pressure-sensitive adhesive sheet (Comparative Example 2) to be manufactured without using the acrylic resin having a high weight average molecular weight is finally a sheet. It could not be formed into a shape. Moreover, in the heat conductive pressure-sensitive adhesive sheet (Comparative Example 3 and Comparative Example 4) made of an acrylic resin composition not containing expanded graphite powder, the thermal conductivity is low regardless of the type and amount of the acrylic resin used. became. Specifically, the heat conductive pressure-sensitive adhesive sheet of Comparative Example 3 and the heat conductive pressure-sensitive adhesive sheet of Example 3 were prepared using the same amount of the same type of acrylic resin. The conductivity was much lower. The heat conductive pressure-sensitive adhesive sheet of Comparative Example 4 and the heat conductive pressure-sensitive adhesive sheet of Comparative Example 1 were prepared using the same amount of the same type of acrylic resin. However, Comparative Example 4 has a much lower thermal conductivity. became.
In addition, about holding force, it turned out that sufficient intensity | strength will be acquired if it can shape | mold into a sheet form from the acrylic resin composition used in the present Example and the comparative example.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, it can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the acrylic resin composition, the heat-conductive pressure-sensitive adhesive sheet, and the heat-conduction with such a change It should be understood that the production method and composite of the pressure-sensitive adhesive sheet are also included in the technical scope of the present invention.

It is a figure which shows roughly a part of heat conductive pressure-sensitive-adhesive sheet preparation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum plane plate 2 Thickness adjustment frame 3 Polyethylene terephthalate film 4 Thermally conductive pressure-sensitive adhesive composition 5 Polyethylene terephthalate film

Claims (9)

(Meth) acrylic acid ester polymer (A1) having a weight average molecular weight of 100,000 to 500,000, (meth) acrylic acid ester polymer (A2) having a weight average molecular weight of 1,000 to 5,000, and (meth) acrylic An acrylic resin composition (F) containing an acid ester monomer (A3m) and expanded graphite powder (E). The acrylic resin composition (F) according to claim 1, further comprising aluminum hydroxide . The acrylic resin composition (F) according to claim 1 or 2 , wherein the (meth) acrylic acid ester polymer (A1) contains a monomer unit (a2) having an organic acid group. ). The acrylic resin composition according to claim 3 , wherein the (meth) acrylic acid ester polymer (A2) contains a monomer unit (a3) having a hydroxyl group or an epoxy group. F). The content of the (meth) acrylic acid ester polymer (A1) is 10 with respect to the total amount of the (meth) acrylic acid ester polymer (A1) and the (meth) acrylic acid ester polymer (A2). The acrylic resin composition (F) according to any one of claims 1 to 4 , which is mass% to 70 mass%. 100 parts by mass of an acrylic resin mixture comprising 10% by mass to 70% by mass of the (meth) acrylic acid ester polymer (A1) and 90% by mass to 30% by mass of the (meth) acrylic acid ester polymer (A2), Contains 25 to 100 parts by weight of a (meth) acrylic acid ester monomer (A3m), 10 to 100 parts by weight of the expanded graphite powder (E), and 50 to 400 parts by weight of the aluminum hydroxide. The acrylic resin composition (F) according to any one of claims 2 to 5 . A heat conductive pressure-sensitive adhesive sheet (G) obtained by heating and molding the acrylic resin composition (F) according to any one of claims 1 to 6 . A method for producing a heat conductive pressure-sensitive adhesive sheet (G), wherein the acrylic resin composition (F) according to any one of claims 1 to 6 is heated and formed into a sheet shape. The composite_body | complex (H) which provides the heat conductive pressure-sensitive-adhesive sheet (G) of Claim 7 on the single side | surface or both surfaces of a base material.

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