JP2013006951A - Heat-conductive pressure-sensitive adhesive composition, heat-conductive pressure-sensitive adhesive sheet type molded article, method for producing the composition and the molded article, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-conductive pressure-sensitive adhesive composition and a heat-conductive pressure-sensitive adhesive sheet type molded article having good productivity and high thermal conductivity, to provide methods for producing the composition and the molded article, and an electronic apparatus including the heat-conductive pressure-sensitive adhesive composition or the heat-conductive pressure-sensitive adhesive sheet type molded article.SOLUTION: The heat-conductive pressure-sensitive adhesive composition is prepared by heating a mixture composition containing a (meth)acrylic resin composition (A) containing a (meth)acrylate polymer (A1) and a (meth)acrylate monomer (α1) of 100 pts.mass, expanded graphite powder (B) of 5 to 70 pts.mass, and expandable graphite (C) of 2 to 15 pts.mass, at a temperature of 115°C or higher and 175°C or lower, to carry out at least polymerization reaction of the (meth)acrylate monomer (α1) and expansion of the expandable graphite (C).

Description

  The present invention relates to a heat conductive pressure-sensitive adhesive composition, a heat conductive pressure-sensitive adhesive sheet-like molded article, a production method thereof, and the heat conductive pressure-sensitive adhesive composition or the heat conductive pressure-sensitive adhesive sheet-like molding. The present invention relates to an electronic device having a body.

  2. Description of the Related Art In recent years, the amount of heat generated by electronic components such as integrated circuit (IC) chips provided in electronic devices such as plasma display panels and personal computers has increased along with higher performance. As a result, there is a need to take measures against functional failures due to temperature rise. In general, a method of dissipating heat by attaching a heat sink such as a metal heat sink, a heat radiating plate, or a heat radiating fin to a heat generator provided in an electronic component or the like is employed. In order to efficiently conduct heat conduction from the heat generating body to the heat radiating body, various heat conducting sheets are used. In general, in applications where a heating element and a radiator are fixed, a composition having a pressure-sensitive adhesive property in addition to thermal conductivity (hereinafter referred to as a “thermal conductive pressure-sensitive adhesive composition”) or sheet. (Hereinafter referred to as “thermally conductive pressure-sensitive adhesive sheet-like molded product”).

  The heat conductive pressure-sensitive adhesive composition and the heat conductive pressure-sensitive adhesive sheet-like molded body have a high thermal conductivity because the main purpose is to transmit heat from the heating element to the heat radiating body. In order to increase the thermal conductivity of the thermally conductive pressure-sensitive adhesive composition or the thermally conductive pressure-sensitive adhesive sheet-like molded article, it is conceivable to add a filler having a high thermal conductivity such as graphite. As a technique for combining a resin composition and graphite, for example, Patent Document 1 discloses an expanded resin (expanded graphite; see paragraph 0003 of Patent Document 1) or an acrylic resin made of at least partially compressed expanded graphite; A resin-impregnated body containing is disclosed. Patent Document 2 discloses a thermally conductive sheet containing a (meth) acrylic polymer and expanded graphite.

Japanese Patent Laid-Open No. 2002-256083 JP 2005-226007 A

  Graphite has high thermal conductivity, and the thermal conductivity of the composition can be improved by adding it to the resin composition. Further, since the expanded graphite is bulky, it is considered that when such graphite is used, the graphite is connected to each other in the resin composition to easily form a heat conduction path, and the thermal conductivity is easily improved.

  However, expanded graphite is easy to take in liquid components due to its structure, and when added to the resin composition, the fluidity of the resin composition may be lowered. It becomes difficult to mold a resin composition having lowered fluidity into a sheet or the like. Therefore, when the resin composition is formed into a sheet shape like the thermally conductive sheet described in Patent Document 2, a large amount of expanded graphite cannot be added to the resin composition. That is, in the prior art, it has been difficult to achieve both the productivity and the thermal conductivity improvement of the heat conductive pressure-sensitive adhesive composition and the heat conductive pressure-sensitive adhesive sheet-like molded body. The technique described in Patent Document 1 is a technique for impregnating expanded graphite with an acrylic resin, and is different in concept from a technique for molding a resin composition containing expanded graphite.

  In view of the above problems, the present invention provides a heat-sensitive pressure-sensitive adhesive composition and a heat-conductive pressure-sensitive adhesive sheet-like molded article having good productivity and high heat conductivity, a method for producing these, and the heat-conductive feeling. It is an object of the present invention to provide a pressure adhesive composition or an electronic device including the thermally conductive pressure-sensitive adhesive sheet-like molded body.

  The present inventors have found that the above-mentioned problems can be solved by using predetermined graphite in combination under predetermined conditions, and have completed the present invention.

  In the first aspect of the present invention, 100 mass of (meth) acrylic resin composition (A) containing (meth) acrylic acid ester polymer (A1) and (meth) acrylic acid ester monomer (α1). Part mixture, 5 to 70 parts by mass of expanded graphite powder (B), and 2 to 15 parts by mass of expandable graphite (C). The thermally conductive pressure-sensitive adhesive composition (at least) is subjected to a polymerization reaction of the (meth) acrylic acid ester monomer (α1) and expansion of the expandable graphite (C). F).

  In the present invention, “(meth) acryl” means “acryl and / or methacryl”. The “expanded graphite powder” means a powdery body obtained by expanding and pulverizing graphite, as will be described in detail later. The term “expandable graphite” means graphite that can be expanded by heating, as will be described in detail later. The “polymerization reaction of (meth) acrylate monomer (α1)” means a polymerization reaction for obtaining a polymer containing a structural unit derived from (meth) acrylate monomer (α1). In addition, as described below as a preferred embodiment, “(meth) acrylic acid ester polymer (A1) and / or (meth) acrylic acid ester monomer (α1) -derived polymer cross-linking reaction” Cross-linking reaction between (meth) acrylic acid ester polymers (A1), cross-linking reaction between polymers containing structural units derived from (meth) acrylic acid ester monomer (α1), and (meth) acrylic acid ester weight Among the crosslinking reactions of the polymer (A1) and the polymer containing a structural unit derived from the (meth) acrylic acid ester monomer (α1), it means one or a plurality of crosslinking reactions.

  In the second aspect of the present invention, 100 mass of (meth) acrylic resin composition (A) containing (meth) acrylic acid ester polymer (A1) and (meth) acrylic acid ester monomer (α1). And after forming the mixed composition containing 5 parts by mass and 70 parts by mass of expanded graphite powder (B) and 2 parts by mass to 15 parts by mass of expandable graphite (C) into a sheet shape Or while forming the mixed composition into a sheet, the mixed composition is heated at a temperature of 115 ° C. or higher and 175 ° C. or lower to polymerize and expand the (meth) acrylic acid ester monomer (α1). It is a heat conductive pressure-sensitive-adhesive sheet-like molded body (G) formed by at least expansion of the conductive graphite (C).

  In the third aspect of the present invention, 100 mass of (meth) acrylic resin composition (A) containing (meth) acrylic acid ester polymer (A1) and (meth) acrylic acid ester monomer (α1). A step of preparing a mixed composition comprising 5 parts by weight and 70 parts by weight or less of expanded graphite powder (B) and 2 parts by weight or more and 15 parts by weight or less of expandable graphite (C), and Heating the mixed composition at a temperature of 115 ° C. or higher and 175 ° C. or lower to perform a polymerization reaction of the (meth) acrylate monomer (α1) and expansion of the expandable graphite (C). The method for producing a heat conductive pressure-sensitive adhesive composition (F).

  The 4th aspect of this invention is 100 masses of (meth) acrylic-ester resin compositions (A) containing the (meth) acrylic-ester polymer (A1) and the (meth) acrylic-ester monomer ((alpha) 1). A step of preparing a mixed composition comprising 5 parts by weight and 70 parts by weight or less of expanded graphite powder (B) and 2 parts by weight or more and 15 parts by weight or less of expandable graphite (C), and After forming the mixed composition into a sheet shape, or while forming the mixed composition into a sheet shape, the mixed composition is heated at a temperature of 115 ° C. or higher and 175 ° C. or lower to obtain a (meth) acrylic ester. It is a manufacturing method of a heat conductive pressure-sensitive-adhesive sheet-like molded object (G) including the process of performing the polymerization reaction of a monomer ((alpha) 1), and the expansion | swelling of expansive graphite (C).

  According to a fifth aspect of the present invention, there is provided a heat radiator and the heat conductive pressure-sensitive adhesive composition (F) of the first aspect of the present invention bonded to the heat radiator, or the heat radiator and the heat radiator. It is the electronic device provided with the heat conductive pressure-sensitive-adhesive sheet-like molded object (G) of the 2nd aspect of this invention combined.

  According to the present invention, a thermally conductive pressure-sensitive adhesive composition and a thermally conductive pressure-sensitive adhesive sheet-shaped molded article having good productivity and high thermal conductivity, a production method thereof, and the thermally conductive pressure-sensitive adhesive. An electronic device provided with the composition or the heat-conductive pressure-sensitive adhesive sheet-like molded product can be provided.

1. Thermally conductive pressure-sensitive adhesive composition (F), thermally conductive pressure-sensitive adhesive sheet-like molded body (G)
The thermally conductive pressure-sensitive adhesive composition (F) of the present invention comprises a (meth) acrylic resin composition containing a (meth) acrylic acid ester polymer (A1) and a (meth) acrylic acid ester monomer (α1). A mixed composition containing the product (A), the expanded graphite powder (B), and the expandable graphite (C) is heated at a temperature of 115 ° C. or higher and 175 ° C. or lower to obtain a single (meth) acrylate ester The polymerization reaction of the body (α1) and the expansion of the expandable graphite (C) are performed at least. Moreover, the heat conductive pressure-sensitive-adhesive sheet-like molded object (G) of this invention is 115 degreeC or more and 175 degreeC after shape | molding the said mixed composition in a sheet form, or shape | molding in a sheet form. By heating at the following temperature, at least the polymerization reaction of the (meth) acrylic acid ester monomer (α1) and the expansion of the expandable graphite (C) are performed. The substance etc. which comprise a heat conductive pressure sensitive adhesive composition (F) and a heat conductive pressure sensitive adhesive sheet-like molded object (G) are demonstrated below.

<(Meth) acrylic resin composition (A)>
The (meth) acrylic resin composition (A) used in the present invention contains a (meth) acrylic acid ester polymer (A1) and a (meth) acrylic acid ester monomer (α1). In obtaining the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G), a polymerization reaction of the (meth) acrylate monomer (α1), It is preferable to perform a crosslinking reaction of a polymer containing a structural unit derived from the (meth) acrylic acid ester polymer (A1) and / or the (meth) acrylic acid ester monomer (α1). That is, a polymerization reaction for obtaining a polymer containing a structural unit derived from a (meth) acrylate monomer (α1), a crosslinking reaction between (meth) acrylate polymers (A1), (meth) acrylic acid Crosslinking reaction between polymers containing a structural unit derived from an ester monomer (α1), and a structural unit derived from a (meth) acrylic acid ester polymer (A1) and a (meth) acrylic acid ester monomer (α1) It is preferable to carry out at least one of the crosslinking reactions with a polymer containing The polymer containing the structural unit derived from the (meth) acrylic acid ester monomer (α1) is preferably mixed with the component of the (meth) acrylic acid ester polymer (A1) by performing the polymerization reaction and preferably a crosslinking reaction. / Or partly combined.

  In this invention, the usage-amount of an acrylic ester polymer (A1) and the (meth) acrylic ester monomer ((alpha) 1) is (meth) with respect to 100 mass% of (meth) acrylic resin compositions (A). The acrylic acid ester polymer (A1) is preferably 5% by mass or more and 40% by mass or less, and the (meth) acrylic acid ester monomer (α1) is preferably 60% by mass or more and 95% by mass or less. By setting the content ratio of the (meth) acrylic acid ester monomer (α1) within the above range, the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) are formed. Easy to do.

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

  The (meth) acrylic acid ester monomer (a1m) which gives the unit (a1) of the (meth) acrylic acid ester monomer is not particularly limited. For example, ethyl acrylate (the glass transition temperature of the homopolymer is -24 ° C), n-propyl acrylate (-37 ° C), n-butyl acrylate (-54 ° C), sec-butyl acrylate (-22 ° C), n-heptyl acrylate (- 60 ° C), n-hexyl acrylate (-61 ° C), n-octyl acrylate (-65 ° C), 2-ethylhexyl acrylate (-50 ° C), 2-methoxyethyl acrylate (-50) ° C), 3-methoxypropyl acrylate (-75 ° C), 3-methoxybutyl acrylate (-56 ° C), ethoxymethyl acrylate (-50 ° C), n-octyl methacrylate (-2) ° C.), can be mentioned methacrylic acid n- decyl (the -49 ° C.) and the like. Among these, n-butyl acrylate, 2-ethylhexyl acrylate, and 2-methoxyethyl acrylate are preferable, n-butyl acrylate and 2-ethylhexyl acrylate are more preferable, and 2-ethylhexyl acrylate is more preferable. These (meth) acrylic acid ester monomers (a1m) may be used individually by 1 type, and may use 2 or more types together.

  In the (meth) acrylic acid ester monomer (a1m), the monomer unit (a1) derived therefrom is preferably 80% by mass or more and 99.9% by mass in the (meth) acrylic acid ester polymer (A1). Hereinafter, it is used for the polymerization in such an amount that it is 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 viscosity of the polymerization system at the time of polymerization can be easily maintained within an appropriate range.

  Next, the monomer unit (a2) having an organic acid group will be described. The monomer (a2m) that gives the monomer unit (a2) having an organic acid group is not particularly limited, but representative examples thereof include organic acid groups such as a carboxyl group, an acid anhydride group, and a sulfonic acid group. The monomer which has can be mentioned. 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 the β-ethylenically unsaturated polyvalent carboxylic acid, α, β-ethylenically unsaturated polyvalent carboxylic acid partial esters such as monomethyl itaconate, monobutyl maleate, monopropyl fumarate and the like can be mentioned. 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.

  As the monomer (a2m), among the monomers having an organic acid group exemplified above, a monomer having a carboxyl group is more preferable, and among them, a monomer having an acrylic acid moiety or a methacrylic acid moiety is preferable. Particularly preferred. These monomers are industrially inexpensive and can be easily obtained, have good copolymerizability with other monomer components, and are preferable in terms of productivity. In addition, a monomer (a2m) may be used individually by 1 type, and may use 2 or more types together.

  In the monomer (a2m) having an organic acid group, the monomer unit (a2) derived from the monomer unit (a2) is preferably 0.1% by mass or more and 20% by mass or less in the (meth) acrylic acid ester polymer (A1). More preferably, it is used for the polymerization in such an amount that it is 0.5 mass% or more and 15 mass% or less. When the usage-amount of the monomer (a2m) which has an organic acid group exists in the said range, it will become easy to maintain the viscosity of the polymerization system at the time of superposition | polymerization in an appropriate range.

  The monomer unit (a2) having an organic acid group is introduced into the (meth) acrylic acid ester polymer (A1) by polymerization of the monomer (a2m) having an organic acid group as described above. Although it is simple and preferable to carry out, an organic acid group may be introduced by a known polymer reaction after the (meth) acrylic acid ester polymer (A1) is produced.

  The (meth) acrylic acid ester polymer (A1) may contain a monomer unit (a3) derived from a monomer (a3m) having 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 (meth) acrylic acid 2-hydroxyethyl and (meth) acrylic acid 3-hydroxypropyl.

  Examples of the monomer having 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.

  As the monomer (a3m) having a functional group other than the organic acid group, one type may be used alone, or two or more types may be used in combination.

  In the monomer (a3m) having a functional group other than these organic acid groups, the monomer unit (a3) derived therefrom is 10% by mass or less in the (meth) acrylate polymer (A1). It is preferable to use it for polymerization in such an amount. By using the monomer (a3m) of 10% by mass or less, it becomes easy to keep the viscosity of the polymerization system during polymerization in an appropriate range.

  The (meth) acrylic acid ester polymer (A1) has a (meth) acrylic acid ester monomer unit (a1) that forms a homopolymer having the above-described 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) having a functional group other than an organic acid group, a monomer derived from the monomer (a4m) copolymerizable with the above-described monomer. 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 specific examples thereof include (meth) acrylate monomers other than the (meth) acrylate monomer (a1m), α, β-ethylenic monomers. Saturated polycarboxylic acid complete ester monomer, alkenyl aromatic monomer, conjugated diene monomer, non-conjugated diene monomer, vinyl cyanide monomer, carboxylic acid unsaturated alcohol ester monomer, Examples include olefinic monomers.

  Specific examples of the (meth) acrylate monomer other than the (meth) acrylate monomer (a1m) include methyl acrylate (homopolymer having a glass transition temperature of 10 ° C.), methyl methacrylate. (105 ° C.), ethyl methacrylate (63 ° C.), n-propyl methacrylate (25 ° C.), and n-butyl methacrylate (20 ° C.).

  Specific examples of the α, β-ethylenically unsaturated polycarboxylic acid complete ester monomer 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 (A1) is measured by gel permeation chromatography (GPC method) and is in the range of 100,000 to 1,000,000 in terms of standard polystyrene. It is more preferable that it is in the range of 200,000 or more and 500,000 or less.

  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. However, solution polymerization is preferable. Among these, solution polymerization using a carboxylic acid ester such as ethyl acetate or ethyl lactate or an aromatic solvent such as benzene, toluene or xylene is more preferable. 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) Etc.

  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. For example, 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.

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

  As an example of the (meth) acrylic acid ester monomer (a5m) for molding 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 (A1) (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 ratio of the (meth) acrylate monomer (a5m) in the (meth) acrylate monomer (α1) is preferably 50% by mass to 100% by mass, more preferably 75% by mass to 100% by mass. It is as follows. By making the ratio of the (meth) acrylic acid ester monomer (a5m) in the (meth) acrylic acid ester monomer (α1) in the above range, the heat conductive pressure-sensitive adhesive having excellent pressure-sensitive adhesiveness and flexibility. It becomes easy to obtain the agent composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G).

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

  The (meth) acrylate monomer (α1) is a (meth) acrylate monomer (a5m) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower, and can be copolymerized with these monomers. It is good also as a thing containing the monomer (a6m) which has an organic acid group.

  Examples of the monomer (a6m) include monomers having an organic acid group similar to those exemplified as the monomer (a2m) used for the synthesis of the (meth) acrylic acid ester polymer (A1). be able to. A monomer (a6m) may be used individually by 1 type, and may use 2 or more types together.

  The ratio of the monomer (a6m) in the (meth) acrylic acid ester monomer (α1) is preferably 30% by mass or less, and more preferably 10% by mass or less. By setting the ratio of the monomer (a6m) in the (meth) acrylic acid ester monomer (α1) to the above range, the heat conductive pressure-sensitive adhesive composition (F) excellent in pressure-sensitive adhesiveness and flexibility. And it becomes easy to obtain a heat conductive pressure-sensitive-adhesive sheet-like molded object (G).

  The (meth) acrylic acid ester monomer (α1) includes a (meth) acrylic acid ester monomer (a5m), a monomer (a6m) having an organic acid group that can be optionally copolymerized, and these It is good also as a mixture with the monomer (a7m) which can be copolymerized. The ratio of the monomer (a7m) in the (meth) acrylic acid ester monomer (α1) is preferably 20% by mass or less, and more preferably 15% by mass or less.

  Examples of the monomer (a7m) include the monomer (a3m) used for the synthesis of the (meth) acrylic acid ester polymer (A1) and the same amount as those exemplified as the monomer (a4m). The body can be mentioned. A monomer (a7m) may be used individually by 1 type, and may use 2 or more types together.

<Polymerization initiator>
When obtaining the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded product (G), the (meth) acrylic acid ester monomer (α1) and a polyfunctional monomer described below are used. The body polymerizes. In order to accelerate the polymerization, it is preferable to use a polymerization initiator.

  Examples of the polymerization initiator that can be used in the present invention include a photopolymerization initiator, an azo thermal polymerization initiator, and an organic peroxide thermal polymerization initiator. From the viewpoint of imparting excellent adhesiveness to the obtained heat conductive pressure-sensitive adhesive composition (F) and heat conductive pressure-sensitive adhesive sheet-like molded body (G), an organic peroxide thermal polymerization initiator is used. It is preferable to use it.

  Various known photopolymerization initiators can be used as the photopolymerization initiator. Of these, acylphosphine oxide compounds are preferred. Examples of the acylphosphine oxide compound that is a preferred photopolymerization initiator include bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and the like.

  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 ( and a peroxide such as t-butylperoxy) -3,3,5-trimethylcyclohexanone. However, those that do not release volatile substances that cause odor during thermal decomposition are preferred. Among organic peroxide thermal polymerization initiators, those having a 1-minute half-life temperature of 100 ° C. or more and 170 ° C. or less are preferable.

  The amount of the polymerization initiator used is preferably 0.01 parts by mass or more and 10 parts by mass or less, and 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic resin composition (A). It is more preferable that it is 0.3 mass part or more and 1 mass part or less. By making the usage-amount of a polymerization initiator into the said range, it becomes easy to make the polymerization conversion of a (meth) acrylic acid ester monomer ((alpha) 1) into an appropriate range, and a heat conductive pressure sensitive adhesive composition (F) and It becomes easy to prevent the monomer odor from remaining in the heat conductive pressure-sensitive adhesive sheet-like molded body (G). The polymerization conversion rate of the (meth) acrylic acid ester monomer (α1) is preferably 95% by mass or more. If the polymerization conversion rate of the (meth) acrylic acid ester monomer (α1) is 95% by mass or more, the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded product (G). It is easy to prevent the monomer odor from remaining on the surface. Moreover, by making the usage-amount of a polymerization initiator into the said range, the excessive (rapid) progress of a polymerization reaction is prevented, As a result, a heat conductive pressure-sensitive-adhesive sheet-like molded object (G) is a smooth sheet | seat. It becomes easy to prevent the situation where it does not become a shape or causes material destruction.

<Multifunctional monomer>
In the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) of the present invention, it is preferable to use a polyfunctional monomer. As the polyfunctional monomer, one that can be copolymerized with the monomer contained in the (meth) acrylic acid ester monomer (α1) is used. Moreover, the polyfunctional monomer has a plurality of polymerizable unsaturated bonds, and preferably has the unsaturated bond at the terminal. By using such a polyfunctional monomer, intramolecular and / or intermolecular crosslinking is introduced into the copolymer, and the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet are introduced. The cohesive force as a pressure-sensitive adhesive of the shaped molded body (G) can be increased.

  Usually, at the time of polymerization such as radical thermal polymerization, a certain degree of crosslinking reaction may proceed without using a polyfunctional monomer. However, in order to form a desired amount of a crosslinked structure more reliably, it is preferable to use a polyfunctional monomer.

  Examples of the polyfunctional monomer include 1,6-hexanediol di (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, and 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, ditrimethylol Polyfunctional (meth) acrylates such as propane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 2,4-bis (trichloro) Other substituted triazines such as methyl) -6-p-methoxystyrene-5-triazine, can be used monoethylenically unsaturated aromatic ketones such as 4-acryloxy benzophenone. Among these, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol tetra (meth) acrylate are preferable. A polyfunctional monomer may be used individually by 1 type, and may use 2 or more types together.

  The amount of the polyfunctional monomer used in the production of the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is the same as that of the (meth) acrylic resin composition (A). 100 parts by mass is preferably 0.1 parts by mass or more and 15 parts by mass or less, more preferably 0.2 parts by mass or more and 8 parts by mass or less, and 0.5 parts by mass or more and 2 parts by mass or less. More preferably. By setting the amount of the polyfunctional monomer used in the above range, the heat conductive pressure sensitive adhesive composition (F) and the heat conductive pressure sensitive adhesive sheet-like molded body (G) are suitable as a pressure sensitive adhesive. It becomes easy to give a strong cohesive force.

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

  As described above, when adding expanded graphite such as expanded graphite powder (B) to improve the thermal conductivity of the resin composition, the flowability of the resin composition decreases when a large amount of the graphite is added. As a result, there is a problem that it cannot be formed into a sheet or the like. According to the present invention, by using a combination of expanded graphite powder (B) and expandable graphite (C) described later, a heat conductive pressure sensitive adhesive composition (F) and a heat conductive pressure sensitive adhesive sheet form. Highly heat-sensitive pressure-sensitive adhesive composition (F) and heat-conductive pressure-sensitive adhesive sheet-like molded body (G) while providing the fluidity necessary for the mixed composition that forms the molded body (G). Thermal conductivity can be imparted. That is, according to the present invention, both the productivity of the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) and the improvement of the heat conductivity can be achieved. The reason is considered as follows.

  Since expandable graphite (C) is less likely to incorporate liquid components than expanded graphite powder (B), even if expandable graphite (C) is added to the resin composition, the same amount of expanded graphite powder (B) is used. Compared with the case where it adds, it is hard to reduce the fluidity | liquidity of this resin composition. Therefore, expandable graphite (C) and expanded graphite powder (B) are added to the mixed composition that is the basis of the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G). )), The fluidity of the mixed composition is less likely to be lower than when the same amount of expanded graphite powder (B) is added as the total amount thereof (that is, it is easy to flow). keep). When the mixed composition containing the expandable graphite (C) and the expanded graphite powder (B) is heated, the expandable graphite (C) expands as will be described later, and the expanded graphite dispersed in the mixed composition. Thermally conductive pressure-sensitive adhesive composition (F) and thermally conductive pressure-sensitive adhesive in which a thermally conductive path is formed by connecting the expanded graphite (C) expanded between the powders (B) and the thermal conductivity is improved It is considered that a sheet-like molded article (G) can be obtained.

  The average particle size of the expanded graphite powder (B) used in the present invention is preferably 10 μm or more and 1000 μm or less, more preferably 20 μm or more and 700 μm or less, and further preferably 30 μm or more and 500 μm or less. By setting the average particle size of the expanded graphite powder (B) in the above range, it becomes easy to form a heat conduction path, and it is easy to suppress the situation where the expanded graphite powder (B) is destroyed.

  In the present invention, the “average particle diameter” means that measured by the method described below. That is, it means that measured by a laser type particle size measuring machine (manufactured by Seishin Enterprise Co., Ltd.) by a micro-sorting control method (a method in which measurement target particles are allowed to pass only in the measurement region and the measurement reliability is improved). . According to this measurement method, by passing 0.01 g to 0.02 g of measurement target particles through the cell, the measurement target particles flowing into the measurement region are irradiated with semiconductor laser light having a wavelength of 670 nm, and the laser at that time By measuring light scattering and diffraction with a measuring instrument, the average particle size and particle size distribution can be calculated from the Franhofer diffraction principle.

  Moreover, the quantity of the expanded graphite powder (B) used for this invention is 5 to 70 mass parts with respect to 100 mass parts of (meth) acrylic resin composition (A). The amount of the expanded graphite powder (B) is preferably 10 parts by mass or more and 60 parts by mass or less, and more preferably 20 parts by mass or more and 50 parts by mass or less. By setting the amount of the expanded graphite powder (B) within the above range, in combination with the expandable graphite (C) described later, the heat conductive pressure sensitive adhesive composition (F) and the heat conductive pressure sensitive adhesive sheet form The heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded product (G) while suppressing the fluidity of the mixed composition that is the basis of the molded product (G). The thermal conductivity of can be improved. When the expanded graphite powder (B) is added beyond the above range, the fluidity of the mixed composition decreases, and the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body ( The productivity of G) may decrease, or the hardness of the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) may increase, resulting in a decrease in shape followability. There is. When the shape followability of the heat conductive pressure-sensitive adhesive composition (F) or the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is lowered, the heat conductive pressure-sensitive adhesive composition is interposed between the heating element and the heat radiating body. When (F) or the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is disposed, it becomes difficult to transfer heat from the heat generating element to the heat radiating element.

<Expandable graphite (C)>
The expandable graphite (C) used in the present invention is graphite that can be expanded by heating. As an example of the expandable graphite (C) used in the present invention, there may be mentioned powdered powder with an acid such as sulfuric acid or nitric acid inserted between natural graphite layers. Such expansive graphite (C), for example, can be expanded to about 100 to 300 times that of graphite crystals by expanding the acid inserted between the layers by rapidly heating to 800 ° C. or more and 1000 ° C. or less. . However, if the expandable graphite (C) is excessively expanded, the thermal conductivity of the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) may be lowered. Moreover, there exists a possibility that the intensity | strength of a heat conductive pressure sensitive adhesive composition (F) and a heat conductive pressure sensitive adhesive sheet-like molded object (G) may become low. On the other hand, if the expansion of the expandable graphite (C) is insufficient, the effect of improving the heat conductivity of the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G). Is insufficient. In the present invention, the expandable graphite (C) is expanded in a mixed composition containing the (meth) acrylic resin composition (A) and the like, so that it is polymerized and optionally crosslinked (meth) acrylic resin composition (A ) Expands the expandable graphite (C). Therefore, after the polymerization or crosslinking reaction of the (meth) acrylic resin composition (A) is finished, the expandable graphite (C) is difficult to expand, so the polymerization or crosslinking reaction of the (meth) acrylic resin composition (A). It is considered that the expandable graphite (C) is expanded before or simultaneously with the reaction.

  The expansion coefficient of the expandable graphite (C) is determined by the mixed composition and the heat conductive pressure sensitive adhesive composition (F) or the heat conductive pressure sensitive adhesive sheet-like molding before and after the expandable graphite (C) is expanded. It can be calculated from the specific gravity of the body (G). The expandable graphite (C) is preferably expanded so that the particle size is 1.5 times or more and 3 times or less, and more preferably 2 times or more and 2.5 times or less.

  The expansion coefficient of the expandable graphite (C) in the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is determined by the heat conductive pressure-sensitive adhesive composition (F) and It is thought that it is influenced by the heating temperature, the heating time, the degree of curing of the (meth) acrylic resin composition (A), etc. when obtaining the heat conductive pressure-sensitive adhesive sheet-like molded product (G). In order to adjust the expansion coefficient of the expandable graphite (C) in the heat conductive pressure sensitive adhesive composition (F) and the heat conductive pressure sensitive adhesive sheet-like molded body (G), the heat conductive pressure sensitive adhesive composition is used. (F) and the method of adjusting the heating temperature or heating time at the time of obtaining a heat conductive pressure-sensitive-adhesive sheet-like molded object (G) are simple. The heating temperature needs to be 115 ° C. or higher and 175 ° C. or lower. Moreover, the said heating time can be about 20 minutes, for example.

  According to the present invention, in order to expand the expandable graphite (C) as described above, the specific gravity of the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is: It becomes smaller than the mixed composition before expanding the expandable graphite (C). Conventionally, it has been considered that the thermal conductivity of the resin composition is lowered when the specific gravity of the resin composition is reduced. However, according to the present invention, the thermally conductive pressure-sensitive adhesive composition (F) and the thermally conductive pressure-sensitive adhesive sheet-like molded product (G) even when the specific gravity is reduced by expanding the expandable graphite (C). Has a high thermal conductivity. Moreover, since specific gravity becomes small, it has the effect that it becomes soft (shape followability increases) and the advantage that a unit price becomes cheap.

  The average particle diameter before expansion of the expandable graphite (C) used in the present invention, that is, the average particle diameter of the expandable graphite (C) before heating the mixed composition is preferably 10 μm or more and 1000 μm or less, It is more preferably 20 μm or more and 700 μm or less, and further preferably 30 μm or more and 500 μm or less. By setting the average particle size of the expandable graphite (C) in the above range, in combination with the expanded graphite powder (B), the heat conductive pressure sensitive adhesive composition (F) and the heat conductive pressure sensitive adhesive sheet The heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded product (G) while suppressing the fluidity of the mixed composition that is the basis of the molded product (G). The thermal conductivity of can be improved.

  Moreover, the quantity of expansive graphite (C) used for this invention is 2 to 15 mass parts with respect to 100 mass parts of (meth) acrylic resin compositions (A). The amount of expandable graphite (C) is preferably 3 parts by mass or more and 12 parts by mass or less, and more preferably 4 parts by mass or more and 10 parts by mass or less. By setting the amount of expandable graphite (C) within the above range, as described above, in combination with the expanded graphite powder (B), the heat conductive pressure sensitive adhesive composition (F) and the heat conductive pressure sensitive adhesive The heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-shaped molded product while suppressing the fluidity of the mixed composition that is the basis of the conductive sheet-shaped molded product (G). The thermal conductivity of (G) can be improved. When the expandable graphite (C) is added beyond the above range, the expandable graphite (C) expands too much when the expandable graphite (C) is expanded, and the thermally conductive pressure-sensitive adhesive composition (F) and Problems such as difficulty in forming a heat conduction path in the heat conductive pressure-sensitive adhesive sheet-shaped molded body (G), and the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-shaped molded body There is a risk that the strength of (G) becomes weak.

<Other additives>
The heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) of the present invention may be added to the heat-sensitive pressure-sensitive adhesive sheet-like molded body (G) in addition to the components described above, as long as the effects of the present invention are not impaired. An agent can also be added. Known additives include foaming agents (including foaming aids); metal oxides, thermally conductive inorganic compounds such as PITCH carbon fibers; flame retardants such as metal hydroxides and metal salt hydrates. Thermally conductive inorganic compounds; flame retardants such as phosphate esters; glass fibers; external cross-linking agents; pigments such as carbon black and titanium dioxide; other fillers such as clay; nanoparticles such as fullerenes and carbon nanotubes; polyphenols and hydroquinones And antioxidants such as hindered amines, thickeners such as acrylic polymer particles, fine silica, and magnesium oxide.

2. Manufacturing method The heat conductive pressure-sensitive adhesive composition (F) of the present invention is prepared by mixing the substances described above and then heating to polymerize the (meth) acrylate monomer (α1), It can be obtained by at least expanding the expandable graphite (C).

  That is, the manufacturing method of the heat conductive pressure-sensitive-adhesive composition (F) of this invention contains the (meth) acrylic acid ester polymer (A1) and the (meth) acrylic acid ester monomer ((alpha) 1) ( A step of preparing a mixed composition comprising the (meth) acrylic resin composition (A), the expanded graphite powder (B), and the expandable graphite (C), and the mixed composition at 115 ° C. to 175 ° C. It includes a step of heating at the following temperature to perform a polymerization reaction of the (meth) acrylic acid ester monomer (α1) and expansion of the expandable graphite (C). Moreover, the manufacturing method of the heat conductive pressure-sensitive-adhesive composition (F) of this invention is the structure derived from the (meth) acrylic acid ester polymer (A1) and / or the (meth) acrylic acid ester monomer (α1). It is preferable to further include a step of performing a crosslinking reaction of the polymer containing the unit. In addition, since the conditions which can be used for others, the preferable content rate of each substance, the preferable average particle diameter of each substance, etc. are as above-mentioned, description is abbreviate | omitted.

  In the method for producing the heat conductive pressure-sensitive adhesive composition (F) of the present invention, for the heating, for example, hot air, an electric heater, infrared rays or the like can be used. The heating temperature and heating time at this time are such that the polymerization initiator is efficiently decomposed, the polymerization of the (meth) acrylic acid ester monomer (α1) and the polyfunctional monomer proceeds, and the expandable graphite ( C) is set to a range that can be appropriately expanded. The temperature range is 115 ° C. or higher and 175 ° C. or lower, and varies depending on the type of polymerization initiator used, but is preferably 120 ° C. or higher and 160 ° C. or lower, and more preferably 125 ° C. or higher and 155 ° C. or lower. The heating time can be, for example, 10 minutes or longer and 30 minutes or shorter, and is preferably 15 minutes or longer and 25 minutes or shorter.

  The heat conductive pressure-sensitive adhesive sheet-shaped molded product (G) of the present invention is obtained by mixing the materials described above into a sheet shape, or while forming into a sheet shape. It can be obtained by performing at least polymerization reaction of the monomer (α1) and expansion of the expandable graphite (C).

  That is, the manufacturing method of the heat conductive pressure-sensitive-adhesive sheet-like molded product (G) of the present invention comprises (meth) acrylic acid ester polymer (A1) and (meth) acrylic acid ester monomer (α1). 100 parts by mass of the (meth) acrylic resin composition (A) containing, 5 parts by mass to 70 parts by mass of expanded graphite powder (B), and 2 parts by mass to 15 parts by mass of expansive graphite (C). And a temperature of 115 ° C. or higher and 175 ° C. or lower after forming the mixed composition into a sheet shape or while forming the mixed composition into a sheet shape. And the step of polymerizing the (meth) acrylic acid ester monomer (α1) and expanding the expandable graphite (C). Moreover, the manufacturing method of the heat conductive pressure-sensitive-adhesive sheet-like molded object (G) of this invention is derived from the (meth) acrylic acid ester polymer (A1) and / or the (meth) acrylic acid ester monomer (α1). It is preferable to further include a step of performing a crosslinking reaction of a polymer containing the structural unit. In addition, since the substance which can be used for others, the preferable content rate of each substance, the preferable average particle diameter of each substance, etc. are as above-mentioned, description is abbreviate | omitted.

  In the method for producing the heat conductive pressure-sensitive adhesive sheet-like molded product (G) of the present invention, the heating conditions are the same as those for the method for producing the heat conductive pressure-sensitive adhesive composition (F), and thus the description thereof is omitted. To do.

  The method for molding the mixed composition into a sheet is not particularly limited. As a suitable method, for example, a cast method in which the mixed composition is applied onto process paper such as a release-treated polyester film (hereinafter sometimes referred to as “release PET film”), a mixed composition, If necessary, the film is sandwiched between two release PET films and passed between rolls installed at a predetermined interval, and when the mixed composition is extruded using an extruder, the thickness is passed through a die. And a method for controlling the thickness.

  The thickness of the heat conductive pressure-sensitive adhesive sheet-like molded body (G) can be 0.05 mm or more and 5 mm or less. By reducing the thickness of the heat conductive pressure-sensitive adhesive sheet-like molded article (G), the thermal resistance in the thickness direction of the heat conductive pressure-sensitive adhesive sheet-like molded article (G) can be reduced. From this viewpoint, the upper limit of the thickness of the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is preferably 3 mm. On the other hand, when the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is applied to the heating element and the heat radiating body by increasing the thickness of the heat-conductive pressure-sensitive adhesive sheet-like molded body (G) to some extent. It is easy to prevent entrainment of air, and as a result, it is possible to prevent an increase in thermal resistance and to improve workability in the step of attaching to the adherend. From such a viewpoint, the lower limit of the thickness of the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is preferably 0.1 mm.

  Moreover, a heat conductive pressure-sensitive-adhesive sheet-like molded object (G) can also be shape | molded on the single side | surface or both surfaces of a base material. The material which comprises the said base material is not specifically limited. Specific examples of the substrate include metals having excellent thermal conductivity such as aluminum, copper, stainless steel, and beryllium copper, and polymers having excellent thermal conductivity such as foils of alloys and thermally conductive silicone. And a sheet-like material made of the above, a heat-conductive plastic film containing a heat-conductive additive, various non-woven fabrics, a glass cloth, a honeycomb structure, and the like. Plastic films include polyimide, polyethylene terephthalate, polyethylene naphthalate, polytetrafluoroethylene, polyether ketone, polyethersulfone, polymethylpentene, polyetherimide, polysulfone, polyphenylene sulfide, polyamideimide, polyesterimide, aromatic polyamide, etc. A heat-resistant polymer film can be used.

3. Use example The heat conductive pressure-sensitive-adhesive composition (F) and heat conductive pressure-sensitive-adhesive sheet-like molded object (G) of this invention can be used as some electronic components etc. with which an electronic device etc. are equipped. In that case, it can shape | mold directly on the base material comprised with a heat radiator etc., and can also be provided as a part of components with which an electronic device is equipped. Specific examples of the electronic device and electronic component include electroluminescence (EL), a component around a heat generating part in a device having a light emitting diode (LED) light source, a component around a power device such as an automobile, a fuel cell, a solar cell, and a battery. , Devices and parts with heat generating parts such as mobile phones, personal digital assistants (PDAs), notebook computers, liquid crystals, surface conduction electron-emitting device displays (SEDs), plasma display panels (PDPs), or integrated circuits (ICs) Can be mentioned.

  In addition, as an example of the usage method for the electronic device of the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded body (G) of the present invention, an LED light source is exemplified below. Examples of usage can be mentioned. 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 housing surrounding the LED light source; pasted on a housing surrounding the LED light source; filling a gap between the LED light source and the housing; Examples of LED light source applications include backlight devices for display devices having transmissive liquid crystal panels (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 composition (F) and heat conductive pressure-sensitive-adhesive sheet-like molded object (G) of this invention, affixing on the housing | casing of an apparatus etc. can be mentioned. For example, when used in a device provided in an automobile or the like, it is affixed inside a casing provided in the automobile; affixed outside the casing provided in the automobile; a heat generating part (inside the casing provided in the automobile) Connecting the car navigation / fuel cell / heat exchanger) and the housing; affixing to a heat sink connected to the heat generating part (car navigation / fuel cell / heat exchanger) in the housing of the automobile; Etc.

  In addition, the heat conductive pressure-sensitive-adhesive composition (F) and heat conductive pressure-sensitive-adhesive sheet-like molded object (G) of this invention can be used with the same method other than a motor vehicle. For example, personal computers; homes; TVs; mobile phones; vending machines; refrigerators; solar cells; surface-conduction electron-emitting device displays (SEDs); organic EL displays; inorganic EL displays; Organic EL display; laptop computer; PDA; fuel cell; semiconductor device; rice cooker; washing machine; laundry dryer; optical semiconductor device combining optical semiconductor elements and phosphors; Is mentioned.

  Furthermore, the heat-conductive pressure-sensitive adhesive composition (F) and the heat-conductive pressure-sensitive adhesive sheet-like molded body (G) of the invention are not limited to the above-described usage methods, and may be used in other methods depending on the application. Is possible. For example, used for heat uniformity of carpets and warm mats, etc .; 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 moisture absorbent; cooling equipment, clothing, towels, sheets, etc. for cooling humans and animals Used on the opposite side of the body to the member Used as a pressure member of a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer; Pressing member of a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer Used as a heat transfer part for heat flow control on which the treatment object of the membrane control device is placed; Used for a heat transfer part for heat flow control on which the treatment object of the film control device is placed; and the outer layer of the radioactive substance storage container It is used between interiors; it is used in a box body provided with a solar panel that absorbs sunlight; it is used between a reflective sheet of a CCFL backlight and an 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.

<Fluidity>
The fluidity of the mixed composition obtained through the first, second, and third mixing steps (first and second mixing steps when the expanded graphite powder is not used) described below was evaluated. Specifically, the Hobart container in which the mixed composition was put was tilted by 30 ° with respect to the horizontal plane, and the state of the mixed composition after 1 minute was evaluated. The results are shown in Tables 1 and 2. The case where the mixed composition flowed along the inclination was indicated as “◯”, and the case where it did not move was indicated as “X”. The fluidity of the mixed composition makes it easier to form the mixed composition into a sheet. That is, it becomes easy to manufacture a heat conductive pressure-sensitive adhesive sheet-like molded body.

<Thermal conductivity>
The thermal conductivity of the heat conductive pressure sensitive adhesive sheet-like molded body was evaluated. It can be said that the higher the thermal conductivity, the higher the thermal conductivity. First, a test piece was prepared by cutting a thermally conductive pressure-sensitive adhesive sheet-like molded body produced as described later into a size of 50 mm width × 110 mm length. Thereafter, the release PET film is peeled from one surface of the test piece, and a wrap film made of polyvinylidene chloride (thickness: 15 μm is formed so as to prevent air from entering so as to cover the entire surface from which the release PET film has been peeled off. ) 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 (QTM-500, manufactured by Kyoto Electronics Industry Co., Ltd.). For the reference plate, silicone sponge (current value: 1A), silicone rubber (current value: 2A), and quartz (current value: 4A) were used in this order. However, when the thermal conductivity exceeded 1.5 W / m · K, quartz (current value: 4 A), zirconia, and mullite were used in this order as the reference plate. The measurement was performed in a 23 ° C. atmosphere. The results are shown in Tables 1 and 2.

<Specific gravity>
A test piece was prepared by cutting a heat-conductive pressure-sensitive adhesive sheet-like molded body produced as described later into a size of 30 mm width × 50 mm length. The test piece was sandwiched between clamps of an automatic hydrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd., DENSIMETER-H) and hung on a hook of a balance in a specific gravity measuring section, and the specific gravity of the test piece was measured.

<Preparation of heat conductive pressure-sensitive adhesive sheet-like molded body>
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 performed 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, 1 part of a polyfunctional monomer obtained by mixing pentaerythritol triacrylate, pentaerythritol tetraacrylate and pentaerythritol diacrylate in a ratio of 60: 35: 5, 70 parts of 2-ethylhexyl acrylate (2EHA), 1 part of an organic peroxide thermal polymerization initiator (1,6-bis (t-butylperoxycarbonyloxy) hexane (1 minute half-life temperature is 150 ° C.)) was weighed with an electronic balance, It mixed with 30 parts of said (meth) acrylic acid ester polymer (A1-1). For the mixing, a thermostatic bath (manufactured by Toki Sangyo Co., Ltd., trade name “Viscomate 150III”) and Hobart mixer (manufactured by Kodaira Seisakusho, trade name “ACM-5LVT type”, capacity: 5 L) were used. The temperature control of the Hobart container was set to 60 ° C., the rotation speed scale was set to 3, and the mixture was stirred for 10 minutes. This process is referred to as a first mixing process.

  Next, 5 parts of expandable graphite (trade name “9950200”, average particle size: 250 μm, manufactured by Ito Graphite Industries Co., Ltd.) are weighed and put into the Hobart container, and the temperature control of the Hobart container is set to 60 ° C. The mixture was stirred for 10 minutes at a rotation speed scale of 5. This process is referred to as a second mixing process.

  Next, 30 parts of expanded graphite powder (product name “EC-50”, average particle size: 250 μm, manufactured by Ito Graphite Industries Co., Ltd.) are weighed and put into the Hobart container, and the inside of the Hobart container is evacuated (−0 0.1 MPa (G)), the temperature control of the Hobart container was set to 60 ° C., the rotation speed scale was set to 3, and the mixture was stirred for 10 minutes while vacuum degassing. This process is referred to as a third mixing process.

  Next, the mixed composition obtained through the first, second, and third mixing steps is hung on a release PET film having a thickness of 50 μm, and another release having a thickness of 50 μm is further formed on the mixed composition. Covered with PET film. This laminate in which the mixed composition was sandwiched between release PET films was passed through a pair of rolls with a distance of 1 mm between them to form a sheet. Thereafter, the laminate was put into an oven and heated at the production temperature shown in Table 1 for 15 minutes. Through this heating step, the (meth) acrylic acid ester monomer is polymerized and cross-linked, and the expandable graphite is expanded to be referred to as a heat conductive pressure-sensitive adhesive sheet-like molded body (hereinafter simply referred to as “sheet”). ) (G1) was obtained. In addition, it was 99.9% when the polymerization conversion rate of the (meth) acrylic acid ester monomer was computed from the amount of residual monomers in a sheet | seat (G1).

(Examples 2 to 8 and Comparative Examples 1 to 7)
Thermally conductive pressure-sensitive adhesives according to Examples 2 to 8 and Comparative Examples 1 to 7 in the same manner as in Example 1 except that the composition of each substance and the production temperature were changed as shown in Tables 1 and 2. A sheet-like molded body was produced. However, when the expanded graphite powder is not used, the third mixing step is not performed. In addition, phosphorus pen-like graphite (manufactured by Ito Graphite Industries Co., Ltd., trade name “CNP35”, average particle size: 30 μm) was mixed in the second mixing step. In Comparative Example 5, the fluidity of the mixed composition was low, and a heat conductive pressure-sensitive adhesive sheet-like molded product could not be produced.

As shown in Table 1, the sheets (G1) to (G8) according to the examples all had good fluidity of the mixed composition before being formed into a sheet shape, and it was easy to form into a sheet shape. . Sheets (G1) to (G8) had high thermal conductivity. On the other hand, as shown in Table 2, are the sheets (GC1) to (GC7) according to the comparative examples difficult to form into a sheet due to poor fluidity of the mixed composition before forming into a sheet? Even if it could be formed into a sheet shape, the thermal conductivity was low. Specifically, it was as follows.
-Comparative example 1: The sheet | seat (GC1) of the comparative example 1 which did not use expansive graphite had low heat conductivity. It can be inferred that the formation of the heat conduction path in the sheet was insufficient because the expansive graphite was not used.
Comparative Example 2: The sheet (GC2) of Comparative Example 2 using limpen-like graphite instead of expanded graphite powder also had a low thermal conductivity. Limpen-like graphite has a smaller volume than expanded graphite powder of the same mass. For this reason, even if the expandable graphite is expanded, it cannot be sufficiently connected between the limpen-like graphite in which the expandable graphite is dispersed, and it can be inferred that the formation of a heat conduction path in the sheet was insufficient.
-Comparative example 3: The sheet | seat (GC3) of the comparative example 3 which replaced with the expansive graphite and used the limpen-like graphite also had low heat conductivity. It can be inferred that the combination of the limpen-like graphite and the expanded graphite powder was insufficient in forming the heat conduction path in the sheet as compared with the combination of the expanded graphite powder and the expandable graphite.
-Comparative example 4: The sheet | seat (GC4) of the comparative example 4 which increased the usage-amount of expansive graphite also had low heat conductivity. Since the specific gravity of the sheet is small, it can be presumed that the voids in the sheet have increased due to the excessive content of the expandable graphite.
Comparative Example 5: In Comparative Example 5, the fluidity of the mixed composition was lowered due to excessive use of the expanded graphite powder, and could not be formed into a sheet.
Comparative Example 6: The sheet (GC6) of Comparative Example 6 also had a low thermal conductivity. It can be inferred that by reducing the production temperature, the expansion of the expandable graphite becomes insufficient, and the formation of the heat conduction path in the sheet was insufficient.
Comparative Example 7: The sheet (GC7) of Comparative Example 7 also had a low thermal conductivity. Since the specific gravity of the sheet is small, it can be inferred that the expansion of the expansive graphite is excessive due to the high production temperature, and the voids in the sheet are increased.

Claims (5)

100 parts by weight of (meth) acrylic acid ester polymer (A1) and (meth) acrylic resin composition (A1) containing (meth) acrylic acid ester monomer (α1),
5 parts by mass or more and 70 parts by mass or less of expanded graphite powder (B),
2 parts by mass or more and 15 parts by mass or less of expansive graphite (C);
A mixed composition containing is heated at a temperature of 115 ° C. or higher and 175 ° C. or lower,
A heat conductive pressure-sensitive adhesive composition (F) comprising at least a polymerization reaction of the (meth) acrylic acid ester monomer (α1) and expansion of the expandable graphite (C). 100 parts by weight of (meth) acrylic acid ester polymer (A1) and (meth) acrylic resin composition (A1) containing (meth) acrylic acid ester monomer (α1),
5 parts by mass or more and 70 parts by mass or less of expanded graphite powder (B),
2 parts by mass or more and 15 parts by mass or less of expansive graphite (C);
Or after forming the mixed composition into a sheet, or while forming the mixed composition into a sheet, heating the mixed composition at a temperature of 115 ° C. or higher and 175 ° C. or lower,
A thermally conductive pressure-sensitive adhesive sheet-like molded article (G), wherein at least polymerization reaction of the (meth) acrylic acid ester monomer (α1) and expansion of the expandable graphite (C) are performed. 100 parts by weight of (meth) acrylic acid ester polymer (A1) and (meth) acrylic resin composition (A1) containing (meth) acrylic acid ester monomer (α1),
5 parts by mass or more and 70 parts by mass or less of expanded graphite powder (B),
2 parts by mass or more and 15 parts by mass or less of expansive graphite (C);
Producing a mixed composition comprising:
Heating the mixed composition at a temperature of 115 ° C. or higher and 175 ° C. or lower to perform a polymerization reaction of the (meth) acrylic acid ester monomer (α1) and expansion of the expandable graphite (C);
The manufacturing method of a heat conductive pressure sensitive adhesive composition (F) containing this. 100 parts by weight of (meth) acrylic acid ester polymer (A1) and (meth) acrylic resin composition (A1) containing (meth) acrylic acid ester monomer (α1),
5 parts by mass or more and 70 parts by mass or less of expanded graphite powder (B),
2 parts by mass or more and 15 parts by mass or less of expansive graphite (C);
Producing a mixed composition comprising:
After forming the mixed composition into a sheet shape or while forming the mixed composition into a sheet shape, the mixed composition is heated at a temperature of 115 ° C. or higher and 175 ° C. or lower to obtain the (meth) acrylic acid. The manufacturing method of a heat conductive pressure-sensitive-adhesive sheet-like molded object (G) including the process of performing the polymerization reaction of ester monomer ((alpha) 1), and the expansion | swelling of the said expandable graphite (C).   The heat conductive pressure-sensitive adhesive composition (F) according to claim 1 bonded to the heat radiator and the heat radiator, or the heat conduction according to claim 2 bonded to the heat radiator and the heat radiator. Electronic device comprising a pressure-sensitive adhesive sheet-like molded body (G).