WO2007116686A1 - Thermally conductive pressure-sensitive adhesive composition and thermally conductive pressure-sensitive adhesive sheet-like molded body - Google Patents

Abstract

Disclosed is a thermally conductive pressure-sensitive adhesive composition (F) obtained by adding a flame-retardant thermally conductive inorganic compound (B) and an expanded graphite powder (E) into an adhesive and/or cohesive composition (S) mainly containing at least one material selected from rubbers, elastomers and resins. Preferably, the composition (S) contains a (meth)acrylate polymer (A1) as a main component; and more preferably, it further contains a (meth)acrylate monomer (A2m). The thermally conductive pressure-sensitive adhesive composition (F) has an excellent balance among flame retardance, hardness and thermal conductivity, and is suitably used as a thermally conductive pressure-sensitive adhesive sheet-like molded body (G) by being molded into a sheet-like shape.

Description

 Specification

 Thermally conductive pressure-sensitive adhesive composition and thermally conductive pressure-sensitive adhesive sheet-like molded article

 [0001] The present invention relates to a heat conductive pressure-sensitive adhesive composition and a heat conductive pressure-sensitive adhesive sheet-like molded article formed therefrom.

 Background art

 In recent years, electronic components such as a plasma display panel (PDP) and an integrated circuit (IC) chip have increased in calorific value as their performance has increased. As a result, there is a need to take measures against functional failures due to temperature rise. Generally, 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 types of heat conductive sheets are used to efficiently conduct heat from the heating element to the heat radiating body. However, in general, a pressure-sensitive adhesive sheet is required for fixing the heating element and the heat radiating element. Is done.

 [0003] Patent Document 1 discloses a heat containing a polymer from a monomer containing a polar monomer copolymerizable with a (meth) acrylic acid alkyl ester, and thermally conductive electrically insulating particles (thermal conductive filler). A conductive electrically insulating pressure sensitive adhesive is disclosed. Specifically, a pressure sensitive adhesive is obtained by photopolymerization by adding a crosslinking agent such as acrylic acid, alumina and tripropylene glycol diatalylate to polyisooctyl acrylate syrup.

 [0004] Patent Document 2 discloses a polyfunctional (meta) (meth) acrylate monomer mixture, a photopolymerization initiator, and a crosslinker that contain a (meth) acrylic acid alkyl ester as a main component and do not contain a polar group-containing monomer. ) A thermally conductive pressure sensitive adhesive comprising a photopolymer of a mixture of attalylate and a thermally conductive filler is disclosed.

 [0005] The pressure-sensitive adhesives disclosed in these documents are difficult to balance between hardness and pressure-sensitive adhesiveness. In reality, photopolymerization is required, and equipment for that is required. It is not economically advantageous.

[0006] Patent Document 3 discloses a heat conductive pressure-sensitive adhesive obtained by blending heat conductive particles with a copolymer of an alkyl (meth) acrylate and a vinyl monomer satisfying a specific formula. Yes. The specific vinyl monomer used here is preferably a special monomer such as (meth) atalylate having a phosphoric acid group or 2-hydroxy-3-phenoxypropyl acrylate.

 This method is not economically advantageous because a large amount of special monomers must be used in order to obtain a reasonable effect, and it balances hardness and pressure-sensitive adhesiveness. There is a problem that is difficult.

 [0007] In order to solve these problems of the prior art, the present applicant has proposed a heat conductive pressure-sensitive adhesive composition containing a specific (meth) acrylate polymer having solvent solubility. Proposed (Patent Document 4) and tried to solve to some extent, but recently, heat conduction pressure-sensitive adhesive composition and heat-conducting pressure-sensitive adhesive sheet-like molded product formed by molding the heat-conducting pressure-sensitive adhesive composition Therefore, there is a tendency to improve the heat resistance. Therefore, it is an issue to balance the thermal conductivity with the conventional flame retardancy and hardness.

 Patent Document 1: Japanese Patent Laid-Open No. 6-088061

 Patent Document 2: Japanese Patent Laid-Open No. 10-324853

 Patent Document 3: Japanese Patent Laid-Open No. 2002-322449

 Patent Document 4: Japanese Patent Laid-Open No. 2002-285121

 Disclosure of the invention

 Problems to be solved by the invention

Accordingly, an object of the present invention is to provide a heat conductive pressure-sensitive adhesive composition and a heat conductive pressure-sensitive adhesive sheet-like molded article having an excellent balance of flame retardancy, hardness and heat conductivity. .

 Means for solving the problem

[0010] The present inventors have continued intensive studies on the heat conductive pressure-sensitive adhesive composition, but the heat conductive pressure-sensitive adhesive comprising a flame retardant heat conductive inorganic compound and expanded graphite powder. The inventors have found that the above object can be achieved by using a composition and a heat conductive pressure-sensitive adhesive sheet-like molded article formed by molding the composition, and based on this finding, the present invention has been completed.

 [0011] In summary, according to the present invention, the heat conductive pressure-sensitive adhesive composition described in the following (1) to (: 12)

(F) and a heat conductive pressure-sensitive adhesive sheet-like molded article according to (13) to (: 18) below are provided Is done.

 (1) A flame retardant thermally conductive inorganic compound (B) is added to an adhesive and / or adhesive composition (S) containing at least one selected from the group consisting of rubber, elastomer and resin as a main component. And thermally conductive pressure-sensitive adhesive composition (F) containing expanded graphite powder (E)

(2) The thermally conductive pressure-sensitive adhesive composition (F) according to the above (1), wherein the expanded graphite powder (E) has a primary average particle size of 5 to 500 μm.

 [0012] (3) Expanded graphite powder (E) is obtained by heat-treating acid-treated graphite at 500 to 1200 ° C.

 The heat conductive pressure-sensitive adhesive composition (F) described in (1) above, which is obtained through a process including swelling to 300 ml / g and then pulverization.

 (4) The heat conductive pressure-sensitive adhesive composition (F) according to the above (1), wherein the flame retardant heat conductive inorganic compound (B) is aluminum hydroxide.

[0013] (5) The thermally conductive pressure-sensitive adhesive composition according to (1), wherein the composition (S) contains a (meth) acrylic acid ester polymer (A1) as a main component. .

 (6) The heat conductive pressure-sensitive adhesive composition (F) according to the above (5), wherein the composition (S) further contains a (meth) acrylic acid ester monomer (A2m).

[0014] (7) The heat conductive pressure-sensitive adhesive composition (F) according to the above (6), further comprising an organic peroxide thermal polymerization initiator (C2).

 (8) (meth) acrylic acid ester polymer (A1) 100 parts by weight, (meth) acrylic acid ester monomer (A2m) 25-100 parts by weight, expanded graphite powder (E) 5-100 parts by weight, difficult Any of the above (5) to (7) comprising 100 to 450 parts by weight of a combustible heat conductive inorganic compound (B) and an organic peroxide thermal polymerization initiator (C2) 0.1 to 10 parts by weight A heat conductive pressure-sensitive adhesive composition (F) according to claim 1.

 [9] (Meth) acrylic acid ester polymer (A1) force Glass transition temperature of -20 ° C or less Unit of (meth) acrylic acid ester monomer forming a homopolymer (al) 80 The heat conductive pressure-sensitive adhesive composition (F) described in (8) above, which comprises ˜99.9% by weight and 20 to 0.1% by weight of the monomer unit (a2) having an organic acid group.

(10) The weight average molecular weight (Mw) of the (meth) acrylic acid ester polymer (A1) is The heat conductive pressure-sensitive adhesive composition (F) as described in (8) above, which is measured in the range of 100,000 to 400,000 as measured by the myelation chromatograph method (GPC method).

[11] (11) (Meth) acrylate monomer (A2m) forms a homopolymer having a glass transition temperature of -20 ° C or lower. (Meth) acrylate monomer (a5m) 70 The (meth) atalinoleic acid ester monomer mixture (A2m ′) consisting of ˜99.9% by weight and an organic acid group-containing monomer (a6m) 30 to 0.1% by weight Thermally conductive pressure sensitive adhesive composition (F).

 (12) The thermally conductive pressure-sensitive adhesive composition (F) according to (8), further comprising 0.01 to 0.8 parts by weight of a thermally decomposable organic foaming agent (D).

[0017] (13) A heat-conductive pressure-sensitive adhesive sheet obtained by molding the heat-conductive pressure-sensitive adhesive composition (F) described in (1) to (: 12) above into a sheet shape. Shaped product (G).

 (14) The heat conductive pressure-sensitive adhesive sheet-like molded article (G) according to the above (13), which is formed by casting.

 [0018] (15) The heat conductive pressure-sensitive adhesive composition (F) according to any one of the above (1) to (12) is molded into a sheet and heated to (meth) acrylic acid Thermally conductive pressure-sensitive adhesive sheet-shaped product (G) obtained by polymerizing ester monomer (A2m).

 (16) The thermally conductive and pressure-sensitive adhesive sheet-like molded article (G) according to any one of (13) to (: 15), which is foamed.

 [0019] (17) The heat conductive pressure-sensitive adhesive sheet-like molded article (G) according to the above (16), which has foam cells having an average diameter of 50 μm to 550 μm.

 (18) The thermally conductive and pressure-sensitive adhesive sheet-like molded article (G) according to (16) or (17), wherein the expansion ratio is 1.01 to 1.5.

 The invention's effect

 [0020] The heat conductive pressure-sensitive adhesive sheet-like molded article of the present invention has good flame retardancy, hardness and heat conductivity, and is excellent in the balance of these properties.

 BEST MODE FOR CARRYING OUT THE INVENTION

[0021] The heat conductive pressure-sensitive adhesive composition (F) of the present invention has adhesiveness and / or tackiness containing at least one selected from the group consisting of rubber, elastomer and resin as a main component. The composition (S) has a flame retardant thermally conductive inorganic compound (B) and an expanded graphite powder (E). Here, “main component” indicates that the total content of components selected from the group consisting of rubber, elastomer and resin is 50% by weight or more based on the weight of the composition (S).

 [0022] (I) Composition (S)

 As the main component constituting the composition (S), at least one selected from rubber, elastomer, and resin can be used. However, the composition (S) needs to have adhesiveness and / or adhesiveness. For this reason, it is preferable to select rubber, elastomer and resin from those having adhesiveness and / or tackiness. However, it is also possible to use a tackifying agent in combination with rubber, elastomer and resin that do not have adhesiveness and / or tackiness.

[0023] Examples of the rubber, elastomer and resin include conjugation polymers such as natural rubber, polybutadiene rubber and polyisoprene rubber; butyl rubber; styrene butadiene copolymer, styrene monoisoprene copolymer rubber, styrene mono Aromatic butyl-conjugated copolymers such as butadiene monoisoprene copolymer rubber, styrene isoprene block copolymer, styrene isoprene styrene block copolymer; Conjugated copolymer hydrogenated product; Atari port Cyanidine copolymer-conjugated copolymer such as nitrile monobutadiene copolymer rubber, acrylonitrile monoisoprene copolymer rubber; acrylonitrile-butadiene copolymer One conjugate of vinyl cyanide compounds, such as hydrogenated products Hydrogenated hydrogenated copolymer; cyanuric vinyl loupe aromatic conjugated diene copolymer; cyanide butyl compound aromatic butyl conjugated conjugated hydrogenated hydrogen copolymer; Mixtures of polymer and poly (nogenized butyl); polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polymethyl methacrylate, polyethyl acrylate, polyethyl methacrylate, poly (n-butyl acrylate) , Poly (n-butyl methacrylate), poly (2-ethylhexyl acrylate), poly (2-ethylhexyl methacrylate), poly [acrylic acid- (n-butyl acrylate)], poly [ Acrylic acid— (2_ethylhexyl acrylate)], poly [acrylic acid— (n-butyl acrylate) — (2_ethylhexyl acrylate)], poly [Methacrylic acid ( Poly (methacrylic acid (2-ethylhexyl acrylate)], poly [methacrylic acid (n-butyl acrylate) (2-ethylhexyl acrylate)], poly [acrylic acid] -Methacrylic acid (acrylic acid n-buter)], poly [acrylic acid-methacrylic acid (acrylic acid 2_ethylhexyl)], poly [acrylic acid-methacrylic acid- (acrylic acid n_butyl)-(acrylic acid 2 _Ethylhexyl)], poly (stearyl acrylate), poly (stearyl methacrylate), and the like (meth) acrylic polymer (here, “(meth) acrylic” means “acrylic and / or methacrylic”). ); Polyhalohydrin rubbers; polyalkylene oxides such as polyethylene oxide and polypropylene oxide; ethylene monopropylene diene Polymer (EPDM); silicone rubber; silicone resins; fluorine rubber; fluorine resin;

Polyethylene; ethylene monopropylene copolymer such as ethylene monopropylene copolymer, ethylene monobutene copolymer; polyolefin polymer such as polypropylene, poly_1-butene, poly_1-octene; Polyhalogenated vinyl resins such as poly (vinyl chloride) resin and polybrominated butyl resin; Polyhalogenated vinylidene resins such as polysalt-vinylidene resin and poly (vinylidene bromide) resin; Epoxy resin; Phenolic resin; Polyphenol Ren-Itel resin; polyamides such as Nylon-6, Nylon-6, 6, Nylon-6, 12; Polyurene; Polyester; Polyacetate vinyl; Poly (ethylene vinyl alcohol); Among them, styrene-isoprene block copolymer, styrene-isoprene styrene block copolymer, poly (ethyl acrylate), poly (n-butyl acrylate), poly (n-butyl methacrylate), poly (2-ethyl acrylate) Hexyl), poly (2-ethylhexyl methacrylate), poly [acrylic acid (butyl acrylate)], poly [acrylic acid (2-ethylhexyl acrylate)], poly [acrylic acid (acrylic acid n -Butyl) mono (2-ethylhexyl acrylate)], poly [methacrylic acid- (n-butyl acrylate)], poly [methacrylic acid- (2-ethylhexyl acrylate)], poly [methacrylic acid- (N_butyl acrylate)-(2_ethylhexyl acrylate)], poly [acrylic acid monomethacrylic acid mono (talylate n-butyl)] Poly [acrylic acid-methacrylic acid- (2-ethylhexyl acrylate)], poly [acrylic acid-methacrylic acid- (n-butyl acrylate)-(acrylic acid 2-ethylhexyl)] force Adhesiveness, adhesion It is preferable because of its excellent properties. More preferably, poly (n-butyl acrylate), poly (n-butyl methacrylate), poly (2-ethylhexyl acrylate) ), Poly (2-ethylhexyl methacrylate), poly [acrylic acid (n-butyl acrylate)], poly [acrylic acid (2-ethylhexyl acrylate)], poly [acrylic acid (acrylic acid n- Butyl) (2-ethylhexyl acrylate)], poly [methacrylic acid (n-butyl acrylate)], poly [methacrylic acid- (2-ethylhexyl acrylate)], poly [methacrylic acid- (acrylic acid) n-butyl) mono (acrylic acid 2_ethylhexyl)], poly [acrylic acid monomethacrylic acid- (acrylic acid n-butyl)], poly [acrylic acid-methacrylic acid- (acrylic acid 2-ethyl acrylate)] Xyl)], poly [acrylic acid monomethacrylic acid mono (acrylic acid n-butyl) mono (atalinoleic acid 2_ethylhexyl)], and more preferably poly [acrylic acid monomethacrylate]. Tacrylic acid— (2-ethylhexyl acrylate)]. These can be used alone or in combination of two or more.

[0025] The main component constituting the composition (S) is preferably a (meth) acrylic acid ester polymer (A1), as will be described in detail later. More preferably, the composition (S) contains the (meth) acrylate polymer (A1) as a main component, and further contains a (meth) acrylate monomer (A2m).

 [0026] Various known materials can be used as the adhesiveness-imparting agent blended into the composition (S) as desired. For example, power including petroleum resin, terpene resin, phenol resin, and rosin resin Among these, petroleum resin is preferable. These may be used alone or in combination of two or more.

 [0027] Examples of petroleum resins include C5 petroleum resins such as pentene, pentagen, and isoprene; C9 petroleum resins obtained from indene, methylindene, vinyl tolylene, styrene, α-methylstyrene, β-methylstyrene, and the like. C5-C9 copolymerized petroleum resins obtained from monomers; petroleum resins obtained from cyclopentagen and dicyclopentagen; and hydrides of those petroleum resins; these petroleum resins are treated with maleic anhydride, maleic acid, fumaric acid, Examples thereof include modified petroleum resins modified with (meth) acrylic acid and phenol.

[0028] Examples of the terpene resin include a monopinene resin, β-vinene resin, and aromatic-modified terpene resin obtained by copolymerizing terpenes such as monopinene and β-pinene and aromatic monomers such as styrene. Etc. can be illustrated. [0029] As the phenol resin, a condensate of phenols and formaldehyde can be used. Examples of the phenols include phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin, and the like. These phenols and formaldehyde are subjected to addition reaction with an alkali catalyst or condensed with an acid catalyst. Examples include novolaks obtained by reaction. Further, a rosin phenol resin obtained by adding phenol to rosin with an acid catalyst and thermal polymerization can be exemplified.

 [0030] Examples of rosin resins include gum rosin, wood rosin or tall oil rosin; stabilized rosin or polymerized rosin obtained by disproportionation or hydrogenation treatment using the rosin; maleic anhydride, maleic acid, fumaric acid, (meth) acrylic Modified rosin modified with acid, phenol, etc .; and esterified products thereof.

 [0031] The alcohol used for esterification to obtain the esterified product is preferably a polyhydric alcohol. Examples thereof include divalent alcoholol such as ethylene glycol, diethylene glycol, propylene glycol and neopentyl glycol; glycerin , Trimethylol ethane, trimethylol propane and other trihydric alcohols; pentaerythritol, diglycerin and other tetrahydric alcohols; dipentaerythritol and other hexavalent alcohols, etc., which may be used alone or in combination of two or more. Can be used.

[0032] The softness point of these adhesiveness-imparting agents is not particularly limited, and those having a high softening point of 200 ° C or lower and liquids at room temperature can be appropriately selected and used.

 [0033] (I) — 1 (Meth) acrylic acid ester polymer (A1)

 The main component constituting the composition (S) is preferably a (meth) acrylic acid ester polymer (A1). More preferably, the composition (S) contains the (meth) acrylic acid ester polymer (A1) as a main component, and further contains a (meth) acrylic acid ester monomer (A2m).

 Hereinafter, the (meth) acrylic acid ester polymer (A1) and the (meth) acrylic acid ester monomer (A2m) will be described in detail.

[0034] The (meth) acrylic acid ester polymer (A1) is not particularly limited, but a (meth) acrylic acid ester monomer unit that forms a homopolymer having a glass transition temperature of -20 ° C or lower ( a 1) 80 to 99.9% by weight, and monomer units (a2) having an organic acid group (a2) 20 to 0.1% by weight are preferably contained. In the present invention, (meth) acrylic acid ester means acrylic acid ester and / or methacrylic acid ester.

 [0035] The (meth) acrylic acid ester monomer (aim) that gives a (meth) acrylic acid ester monomer unit (al) that forms a homopolymer having a glass transition temperature of 20 ° C or lower includes: Although there is no particular limitation, for example, ethyl acrylate (the glass transition temperature of the homopolymer is _24 ° C), propyl acrylate (37-C), butyl acrylate (54-C), acrylic acid sec-butyl (same as 22.C), heptyl acrylate (same as 60.C), hexyl acrylate (same as 61.C), octyl acrylate (same as _65.C), acrylic acid 2_ Ethylhexyl (same _50.C), 2-methoxyethyl acrylate (same 50 ° C), 3-methoxypropyl acrylate (same 75 ° C), 3-methoxybutyl acrylate (same _56 ° C), 2_Ethoxymethyl acrylate (same _50. C), octyl methacrylate (same 25 ° C), decyl methacrylate It can be exemplified (the _49 ° C).

 [0036] These (meth) acrylic acid ester monomers (aim) may be used alone or in combination of two or more.

 These (meth) acrylic acid ester monomers (aim) have monomer units (al) derived from the (meth) acrylic acid ester copolymer (A1), preferably 80 to 99.9% by weight. More preferably, it is used in the polymerization in an amount of 85 to 99.5% by weight. If the amount of the (meth) acrylic acid ester monomer (aim) is within the above range, the heat-conductive pressure-sensitive adhesive sheet-like molded product (G) obtained from this will have a pressure-sensitive adhesive property near room temperature. Excellent.

[0037] The monomer (a2m) that gives the monomer unit (a2) having an organic acid group is not particularly limited, and representative examples thereof include a carboxyl group, an acid anhydride group, and a sulfonic acid group. Examples of such a monomer having an organic acid group can include monomers having a sulfenic acid group, a sulfinic acid group, and a phosphoric acid group. Specific examples of the monomer having a carboxylate group include acrylic acid, methacrylic acid, crotonic acid and the like, β-ethylenically unsaturated monocarboxylic acid; itaconic acid, maleic acid, fumaric acid and the like. , Β-ethylenically unsaturated polyvalent carboxylic acids; β-ethylenically unsaturated polyvalent carboxylic acid partial esters such as methyl itaconate, butyl maleate, and propyl fumarate; It can also be hydrolyzed by maleic anhydride, itaconic anhydride, etc. Those having a group that can be derived to a lpoxyl group can be used as well.

 [0038] Specific examples of the monomer having a sulfonic acid group include allylic sulfonic acid, methallyl sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, and acrylamide β-unsaturated sulfonic acid such as 2-methylpropane sulphonic acid. Mention may be made of acids and their salts. Among these monomers having an organic acid group, acrylic acid and methacrylic acid are particularly preferable among monomers having a carboxyl group. These are industrially inexpensive and can be easily obtained, have good copolymerizability with other monomer components, and are preferable from the viewpoint of productivity.

 [0039] These monomers having an organic acid group (a2m) may be used alone or in combination of two or more.

 These monomers having organic acid groups (a2m) have monomer units (a2) derived therefrom.

In the (meth) acrylic acid ester polymer (A1), it is desirable to use it for polymerization in an amount of 20 to 0.1% by weight, preferably 15 to 0.5% by weight. When used within the above range, the viscosity of the polymerization system at the time of polymerization can be maintained within an appropriate range.

[0040] 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 it is easy and preferable to do this, an organic acid group may be introduced by a known polymer reaction after the (meth) acrylic acid ester polymer is formed.

[0041] The (meth) acrylic acid ester polymer (A1) contains 10% by weight or less of a polymer unit (a3) derived from a monomer (a3m) containing a functional group other than an organic acid group. Les, even okay. Examples of functional groups other than organic acid groups include hydroxyl groups, amino groups, amide groups, epoxy groups, mercapto groups, and the like.

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

 [0042] Examples of the monomer containing an amino group include (meth) acrylic acid N, N-dimethylolaminomethylol,

Examples include (meth) acrylic acid N, N-dimethylaminoethyl, aminostyrene, and the like. Examples of the monomer having an amide group include α, β ethylenically unsaturated carboxylic acid amide monomers such as acrylamide, methacrylolamide, N methylol acrylamide, N methylol methacrylamide, and N, N dimethylacrylamide. it can.

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

 [0043] As the monomer (a3m) containing a functional group other than an organic acid group, one type may be used alone, or two or more types may be used in combination.

 The monomer (a3m) having a functional group other than the organic acid group is such that the monomer unit (a3) derived therefrom is 10% by weight or less in the (meth) acrylate polymer (A1). It is preferably used in the polymerization in an amount. By using a monomer (a3m) of 10% by weight or less, the viscosity during polymerization can be maintained appropriately.

[0044] (Meth) acrylic acid ester polymer (A1) forms a homopolymer having a glass transition temperature of -20 ° C or lower. (Meth) acrylic acid ester monomer unit (al), organic In addition to monomer units ( _a 2) having acid groups and monomer units (a3) containing functional groups other than organic acid groups, monomers copolymerizable with these monomers (a4m The monomer unit (a4) derived from) may be contained.

 As the monomer (a4m), one type may be used alone, or two or more types may be used in combination.

 [0045] The amount of the monomer unit (a4) derived from the monomer (a4m) is preferably 10% by weight or less of the acrylate polymer (A1), more preferably 5% by weight or less. .

 The monomer (a4m) is not particularly limited, and as a specific example thereof, a monomer other than (meth) acrylate monomer (aim) that forms a homopolymer having a glass transition temperature of −20 ° C. or lower. (Meth) acrylic acid ester monomer, ，, / 3_ethylenically unsaturated polyvalent carboxylic acid complete ester, alkenyl aromatic monomer, conjugated gen monomer, non-conjugated gen monomer, cyanide Examples include bulle monomers, carboxylic acid unsaturated alcohol esters, and olefin-based monomers.

[0046] Specific examples of (meth) acrylic acid ester monomers other than (meth) acrylic acid ester monomers (aim) forming a homopolymer having a glass transition temperature of -20 ° C or lower include Methyl acrylate (homopolymer has a glass transition temperature of 10 ° C), methyl methacrylate (105 ° C), Ethyl methacrylate (63 ° C), propyl methacrylate (25 ° C), butyl methacrylate (20 ° C), and the like.

[0047] Specific examples of α, β-ethylenically unsaturated polyvalent carboxylic acid complete esters such as methyl itaconate, butyl maleate, and propyl fumarate include dimethyl fumarate, decyl fumarate, dimethyl maleate, and jetyl maleate. Can mention dimethyl itaconate.

 Specific examples of the alkenyl aromatic monomer include styrene, trimethyl styrene, methyl a-methyl styrene, butyltoluene and dibutenebenzene.

 [0048] Specific examples of the conjugated gen-based monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentane, 2,3-dimethyl-1,3-butadiene, 2_Black-mouth_ 1,3-Butadiene, cyclopentagen and the like can be mentioned.

 Specific examples of the nonconjugated gen-based monomer include 1,4-monohexagen, dicyclopentadiene, ethylidene norbornene and the like.

[0049] Specific examples of the cyanide vinyl monomer include acrylonitrile, methacrylonitrile, _a chloroacrylonitrile, _α- ethyl acrylonitrile and the like.

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

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

 [0050] The weight average molecular weight (Mw) of the (meth) acrylic acid ester polymer (A1) is preferably in the range of 100,000 to 400,000 as measured by gel permeation chromatography (GPC method). A force in the range of 150,000 to 300,000 is more preferable.

The (meth) acrylic acid ester polymer (A1) forms a homopolymer having a glass transition temperature of −20 ° C. or lower. The (meth) acrylic acid ester monomer (aim) is a monomer having an organic acid group. Monomer (a2m), a monomer containing a functional group other than an organic acid group (a 3m) to be used if necessary, and a monomer copolymerizable with these monomers to be used if necessary (A4m) can be particularly preferably obtained by copolymerization. [0051] The method of polymerization is not particularly limited, and may be any of solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, or any other method. Solution polymerization is preferred, and among these, solution polymerization using a carboxylic acid ester such as ethyl acetate or lactic acid ethyl ester or an aromatic solvent such as benzene, toluene or xylene 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.

 [0052] 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; potassium persulfate, sodium persulfate, peroxide Ability to cite persulfates such as ammonium sulfate.

 These peroxides can be used in combination with a reducing agent as appropriate and used as a redox catalyst.

 As the azo compound polymerization initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis ( 2) -Methylbutyronitrile).

 The amount of the polymerization initiator (C1) used is not particularly limited, but is preferably in the range of 0.01 to 50 parts by weight with respect to 100 parts by weight of the monomer.

 There are no particular restrictions on the other polymerization conditions (polymerization temperature, pressure, stirring conditions, etc.) of these monomers.

 [0054] After completion of the polymerization reaction, the obtained polymer is separated from the polymerization medium if necessary. The separation method is not particularly limited. 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.

 [0055] (1)-2 (Meth) acrylic acid ester monomer (A2m)

It is more preferable that the composition (S) further contains a (meth) acrylic acid ester monomer (A2m) in addition to the main component (meth) acrylic acid ester polymer (A1). This application When the heat conductive pressure-sensitive adhesive composition (F) of the invention is molded into a heat conductive pressure-sensitive adhesive sheet-like molded body (G), the (meth) acrylic acid ester alone in the composition (S) is used. The monomer (A2m) is polymerized and converted to a (meth) acrylate polymer.

 [0056] The (meth) acrylic acid ester monomer (A2m) is not particularly limited as long as it is a (meth) acrylic acid ester monomer, but a homopolymer having a glass transition temperature of -20 ° C or lower. Preferably, it is a (meth) acrylic acid ester monomer (a5m) that forms

[0057] Examples of (meth) acrylic acid ester monomers ( _a 5m) that form homopolymers having a glass transition temperature of 20 ° C or lower include (meth) acrylic acid ester polymers (A1) The (meth) acrylic acid ester monomer (aim) used for the synthesis of (meth) acrylic acid ester monomer can be mentioned.

 The (meth) acrylic acid ester monomer (a5m) can be used alone or as a mixture of two or more.

 [0058] The (meth) acrylic acid ester monomer (A2m) is a (meth) acrylic acid ester monomer.

 (a5m) and a mixture (A2m ′) thereof with a copolymerizable monomer may be used. Particularly preferred, (meth) acrylate monomer mixture (A2m ') forms a homopolymer with a glass transition temperature of -20 ° C or less (meth) acrylate monomer (a5m) A monomer mixture (A2m ′) comprising 70 to 99.9% by weight and a monomer having an organic acid group (a6m) 30 to 0.1% by weight. The ratio of the (meth) acrylic acid ester monomer (a5m) in the (meth) acrylic acid ester monomer mixture (A2m ′) is preferably 70 to 9 · 9% by weight, more preferably 75 to 99. % By weight. When the ratio of the (meth) acrylate monomer (a5m) is in the above range, the pressure-sensitive adhesiveness and flexibility of the heat conductive pressure-sensitive adhesive sheet-like molded product (G) are excellent.

 [0059] Examples of the monomer (a6m) having an organic acid group include the same organic acid groups as exemplified as the monomer (a2m) used in the synthesis of the (meth) acrylic acid ester polymer (A1). The monomer which has this can be mentioned. As the monomer having an organic acid group (a6m), one type may be used alone, or two or more types may be used in combination.

[0060] The proportion of the monomer (a6m) having an organic acid group in the (meth) acrylic acid ester monomer mixture (A2m ') is preferably 30 to 0.1% by weight, more preferably 25 to 1% by weight . Specific force of monomer having organic acid group (a6m) When it is within the above range, the heat conductive pressure-sensitive adhesive sheet-like molded product (G) has appropriate hardness and pressure-sensitive at high temperature (100 ° C). Adhesiveness is good.

 [0061] The (meth) acrylic acid ester monomer mixture (A2m ') is composed of 70 to 99.9% by weight of the (meth) acrylic acid ester monomer (a5m) monomer (a6m ) In addition to 30 to 0.1% by weight, a monomer (a7m) copolymerizable therewith can be contained in the range of 20% by weight or less.

[0062] Copolymerizable with (meth) acrylic acid ester monomer ( _a 5m) and monomer having organic acid group (a6m) to form a homopolymer with a glass transition temperature below 120 ° C Examples of such monomers (a7 m) include monomers (a3 m), monomers (a4m) used in the synthesis of (meth) acrylic acid ester polymer (A1), or the polyfunctionality shown below Examples thereof include the same monomers as exemplified as the monomer.

 [0063] 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.

 [0064] The polyfunctional monomer includes 1,6-hexanediol di (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,12-dodecandiol di (meth) Atalylate, Polyethylene glycol di (meth) acrylate, Polypropylene glycol di (meth) acrylate, Neopentyldarlycol di (meth) acrylate, Pentaerythritol di (meth) acrylate, Trimethylolpropane tri (meth) attaly Polyfunctional (meth) atari such as dirate, pentaerythritol tri (meth) atalylate, ditrimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate Rate; 2, 4-bis (trichloromethyl) -6 Substituted Toriajin such p- methoxystyrene one 5-triazine emissions; 4_ acrylic O carboxymethyl benzophenone of such monoethylenically unsaturated saturated aromatic ketones; les use and can Rukoto.

[0065] The amount of the (meth) acrylate monomer (A2m) is usually 25 to 100 parts by weight, preferably 30 to 100 parts by weight of the (meth) acrylate polymer (A1). 50 parts by weight . If the amount of (meth) acrylic acid ester monomer (A2m) is less than the lower limit or exceeds the upper limit of the above range, the heat-sensitive pressure-sensitive adhesive sheet-like molded product (G) may be inferior in pressure-sensitive adhesiveness retention. .

 [0066] (ID m ^ ^ (E)

 The expanded graphite powder (E) constituting the heat conductive pressure-sensitive adhesive composition (F) of the present invention is not particularly limited. Examples of preferred expanded graphite powder include those obtained through a process including heat treatment of acid-treated graphite at 500 to 1200 ° C. to expand to 100 to 300 ml / g and then pulverization. be able to. More preferably, the graphite is treated with strong acid and then sintered in alkali, and then again treated with strong acid is heat-treated at 500 to 1200 ° C to remove the acid and expand to 100 to 300 ml / g. And then obtained through a process including pulverization. The heat treatment temperature in the above is particularly preferred <800 to 1,000. C.

 [0067] The primary average particle size of the expanded graphite powder (E) is preferably 5 to 500 μm, more preferably 30 to 300 μΐη, and even more preferably 50 to 200 / im. . If the primary average particle size of Moon Gung Zhi Black Powder (E) is less than 5 μm, the viscosity of the heat conductive pressure-sensitive adhesive composition (F) will increase excessively, which may cause problems in moldability. . On the other hand, if it exceeds 500 μΐη, the presence of large domains on the surface of the molded product makes it easy to form voids at the interface with the adherend, and there is a risk that thermal conductivity and adhesiveness will be reduced.

 [0068] The amount of the expanded graphite powder (E) with respect to 100 parts by weight of the (meth) acrylic acid ester polymer (A1) is preferably 5 to: 100 parts by weight, more preferably 10 to 50 parts by weight, and still more preferably. 20 to 40 parts by weight.

 If the amount used is less than 5 parts by weight, the thermal conductivity of the heat conductive pressure-sensitive adhesive sheet-like molded product (G) is low, whereas if it exceeds 100 parts by weight, the thermal conductive pressure-sensitive adhesive sheet-like molded product (G The thermal conductivity of) does not increase so much even if the amount of expanded graphite powder (E) added is increased, resulting in inconvenience.

 [0069] (III) 籠 謹 云 魏 馳) (B)

Examples of the flame retardant thermally conductive inorganic compound (B) are not particularly limited, and examples thereof include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, dihydrate gypsum, and boric acid. Examples include zinc, kaolin clay, calcium aluminate, calcium carbonate, aluminum carbonate, and dosonite.

[0070] The flame retardant thermally conductive inorganic compound (B) may be used alone or in combination of two or more.

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

 Among the flame retardant thermally conductive inorganic compounds (B), aluminum hydroxide is particularly preferable. By using aluminum hydroxide, excellent flame retardancy can be imparted to the heat conductive pressure-sensitive adhesive composition (F) and the heat conductive pressure-sensitive adhesive sheet-like molded product (G) of the present invention.

[0071] As the hydroxide alcohol, those having a particle size of 0.2 ^ 150 ^ 111, preferably 0.7 to 100 zm are usually used. Further, it preferably has an average particle diameter of 1 to 80 zm. 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. There is a risk of reducing the shape following ability.

 On the other hand, when the average particle size exceeds 80 / m, the heat conductive pressure-sensitive adhesive sheet-like molded product (G) becomes too soft and excessively pressure-sensitively adheres, the adhesive strength decreases at high temperatures, There is a risk of thermal deformation.

[0072] The amount of the flame retardant thermally conductive inorganic compound (B) with respect to 100 parts by weight of the (meth) acrylic acid ester polymer (Al) is preferably 100 to 450 parts by weight, more preferably 150 to 300 parts by weight. Further, it is preferably 200 to 250 parts by weight.

 If the amount used is less than 100 parts by weight, the heat conductive pressure-sensitive adhesive sheet-like molded product (G) has problems such as high-temperature adhesive strength and reduced thermal conductivity. On the other hand, if it exceeds 450 parts by weight, the thermal conductivity is felt. The hardness of the pressure-adhesive sheet-like molded body (G) increases, resulting in a problem of reduced shape following ability.

[0073] (IV) Other ingredients

 (IV)-1 ^ m ^ ^ m ^ m w (C2)

When the heat conductive pressure-sensitive adhesive sheet-like molded product (G) is molded, the (meth) acrylic acid ester monomer (A2m) in the composition (S) is polymerized. In order to accelerate the polymerization, the composition (F) contains (meth) acrylic acid ester polymer (A1) and (meth) acrylic acid ester unit. In addition to the composition (S) containing the monomer (A2m), it is preferable to further contain an organic peroxide thermal polymerization initiator (C2).

 [0074] Polymerization of (meth) acrylic acid ester monomer (A2m) includes (meth) acrylic acid ester polymer (A1), expanded graphite powder (E), flame retardant thermally conductive inorganic compound (B ), An organic peroxide thermal polymerization initiator (C2), and a thermally decomposable organic foaming agent (D) described later. In the polymerization of the (meth) acrylate monomer (A2m) The conditions are not particularly limited except for the polymerization initiation method.

 [0075] As the polymerization initiator, an organic peroxide thermal polymerization initiator (C2) is used. When a photopolymerization initiator is used in place of the organic peroxide thermal polymerization initiator (C2), the adhesive strength of the resulting heat conductive pressure-sensitive adhesive sheet-shaped article (G) is poor. In addition, when an azo thermal polymerization initiator is used instead of the organic peroxide thermal polymerization initiator (C2), release of nitrogen gas occurs during decomposition, and the thermally conductive pressure-sensitive adhesive sheet-like molded product (G) This is not preferable because foam cells that are not the object of the present invention may be formed.

 [0076] Examples of the organic peroxide thermal polymerization initiator (C2) include hydroperoxides such as t-butyl hydroperoxide; benzoyl peroxide, cyclohexanone peroxide, 1, 6-bis (T-butylperoxycarbonyloxy) hexane (hereinafter sometimes abbreviated as “tBCH”), 1,1-bis (t-butylperoxy) -1,3,5-5-trimethylcyclohexanone (hereinafter referred to as “tBCH”) May be abbreviated as “TMCH.”), But it is preferable not to release volatile substances that cause odor during thermal decomposition. Among the organic peroxide thermal polymerization initiators (C2), those having a one-minute half-life temperature of 120 ° C or higher and 170 ° C or lower are preferable.

 [0077] The amount of the organic peroxide thermal polymerization initiator (C2) used is preferably 0.1 to 10 parts by weight, more preferably 100 parts by weight of the (meth) acrylic acid ester polymer (A1). Is 0.5 to 5 parts by weight, more preferably 0.5 to 2 parts by weight.

 The polymerization conversion rate of the (meth) acrylate monomer (A2m) is preferably 95% by weight or more. If the polymerization conversion rate is too low, a monomer odor remains in the resulting heat conductive pressure-sensitive adhesive sheet-like molded product (G), which is not preferable.

[0078] The thermally conductive pressure-sensitive adhesive composition of the present invention comprising an organic peroxide thermal polymerization initiator (C2) ( F), (meth) acrylic acid ester polymer (Al) 100 parts by weight, (meth) acrylic acid ester monomer (A2m) 25-100 parts by weight, expanded graphite powder (E) 5 :: 100 parts by weight The flame retardant heat conductive inorganic compound (B) is preferably contained in an amount of 100 to 450 parts by weight and the organic peroxide thermal polymerization initiator (C2) 0.

 [0079] The heat conductive pressure-sensitive adhesive composition (F) of the present invention comprises the above-mentioned (meth) acrylic acid ester polymer (A1) 100 parts by weight, (meth) acrylic acid ester monomer (A2m) 20 ~ 200 parts by weight, expanded graphite powder (E) 5 ~: 100 parts by weight, flame retardant thermally conductive inorganic compound (B) 100 to 450 parts by weight and organic peroxide thermal polymerization initiator (C2) 0.1 ~: It is more preferable that 10 parts by weight further contains 0.01 to 0.8 parts by weight of the thermally decomposable organic foaming agent (D).

 [0080] (IV)-2 organic components (D)

 As the thermally decomposable organic foaming agent (D), those having a decomposition initiation temperature of 80 ° C or higher and 200 ° C or lower are preferable.

 Examples of the thermally decomposable organic foaming agent (D) include 4,4′oxybis (benzenesulfonyl hydrazide) (hereinafter sometimes referred to as “OBSH”). The same applies to foaming systems in which a certain amount of foaming aid, described below, is mixed in an organic foaming agent with a thermal decomposition starting temperature higher than 200 ° C, such as azodicarboamide, so that the thermal decomposition starting temperature is 100 ° C or higher and 200 ° C or lower. It can be a thermally decomposable organic foaming agent (D).

 [0081] 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, palmitic acid and zinc white. A mixture of sodium stearate, sodium laurate, sodium palmitate, potassium stearate, potassium laurate, potassium palmitate, and the like.

[0082] The amount of the thermally decomposable organic foaming agent (D) used is preferably 0.01 to 0.8 parts by weight, more preferably 100 parts by weight of the (meth) acrylic acid ester polymer (A1). 0.05 to 0.6 parts by weight, more preferably 0.:! To 0.4 parts by weight, particularly preferably 0.:! To 0.3 parts by weight. Thus, the more the amount of the thermally decomposable organic foaming agent (D) used is within the above-mentioned preferable range, the average diameter of the foamed cell can be adjusted to the preferable range, and the balance between hardness and pressure-sensitive adhesiveness can be achieved. Thermally conductive pressure-sensitive adhesive sheet with excellent shape following and pressure-sensitive adhesive retention Form (G) can be obtained.

 [0083] (IV)-3 External cross-linking agent

 The heat conductive pressure-sensitive adhesive composition (F) of the present invention is added with an external cross-linking agent in order to increase the cohesive force as a pressure-sensitive adhesive and improve heat resistance, and (meth) acrylic. A crosslinked structure can be introduced into a mixture of the acid ester polymer (A1) and the polymer of the (meth) acrylate monomer (A2m).

 [0084] Examples of the external crosslinking agent include polyfunctional isocyanate crosslinking agents such as tolylene diisocyanate, trimethylolpropane diisocyanate, diphenylmethane triisocyanate; diglycidyl ether, polyethylene glycol And epoxy crosslinking agents such as diglycidyl ether and trimethylolpropan triglycidyl ether; melamine resin crosslinking agents; amino resin crosslinking agents; metal salt crosslinking agents; metal chelate crosslinking agents; The external cross-linking agent was added to the (meth) acrylic acid ester polymer (A1) and (meth) acrylic acid ester monomer (A2m) polymer mixture, and then added to this for heat treatment and radiation. By carrying out the irradiation treatment, crosslinks are formed within and / or between the molecules of the copolymer.

 [0085] The heat conductive pressure-sensitive adhesive composition (F) of the present invention comprises expanded graphite powder (E), flame retardant heat conductive inorganic compound), (meth) acrylic acid ester polymer (Al), ( In addition to the above-mentioned proportions of (meth) acrylic acid ester monomer (A2m), organic peroxide thermal polymerization initiator (C2), and thermally decomposable organic foaming agent (D), if necessary, pigments and other fillings It is possible to contain various known additives such as materials, flame retardants, anti-aging agents, thickeners and the like as long as the effects of the present invention are not impaired.

 [0086] As the pigment, any organic or inorganic material such as carbon black other than the expanded graphite powder (E) or titanium dioxide can be used.

 Examples of other fillers include inorganic compounds such as clay. Nanoparticles such as fullerenes and carbon nanotubes may be added.

 Examples of the flame retardant include ammonium polyphosphate, zinc borate, tin compound, organic phosphorus compound, red phosphorus compound, and silicone flame retardant.

[0087] As an anti-aging agent, since it is highly likely to inhibit radical polymerization, it is not usually used. If necessary, an antioxidant such as polyphenol, hydroquinone, or hindered amine can be 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.

 [0088] (V) sheet, book (G)

 The heat conductive pressure-sensitive adhesive sheet-like molded product (G) of the present invention is formed by molding a heat conductive pressure-sensitive adhesive composition (F) into a sheet shape.

[0089] When the content of the (meth) acrylic acid ester monomer (A2m) in the heat conductive pressure-sensitive adhesive composition (F) is 5% by weight or less, the heat conductive pressure-sensitive adhesive composition ( F) can be suitably molded as it is without polymerizing the (meth) acrylic acid ester monomer (A2m).

 [0090] The heat conductive pressure-sensitive adhesive sheet-like molded product (G) of the present invention may be composed of only a heat conductive pressure-sensitive adhesive composition (F) on one side or both sides thereof. It may be a composite comprising a layer of the formed heat conductive pressure sensitive adhesive composition (F).

 The thickness of the layer of the heat conductive pressure-sensitive adhesive composition (F) in the heat conductive pressure-sensitive adhesive sheet-like molded product (G) of the present invention is not particularly limited, but is usually 50 / im to 3 mm. If it is thinner than 50 μm, there is a risk that sufficient heat conductivity cannot be obtained as a result of air being easily trapped when it is applied to the heating element and the radiator. On the other hand, if it is thicker than 3 mm, the heat resistance of the thermally conductive pressure-sensitive adhesive sheet-like molded product (G) increases, and the heat dissipation may be impaired.

 [0091] When the layer of the heat conductive pressure-sensitive adhesive composition is formed on one side or both sides of the substrate, the substrate is not particularly limited.

Specific examples include foils of metals and alloys with excellent thermal conductivity such as aluminum, copper, stainless steel, and beryllium copper; sheet-like materials made of polymers with excellent thermal conductivity such as thermal conductive silicone. A heat conductive plastic film containing a heat conductive filler; various nonwoven fabrics; a glass cloth; a honeycomb structure; Plastic films include polyimide, polyethylene terephthalate, polyethylene naphthalate, polytetrafluoroethylene, polyether ketone, polyether snophone, polymethylpentene, polyetherimide, polysulfone, and polyphenylene sulfide. A film made of a heat resistant polymer such as polyamide imide, polyester imide, or aromatic polyamide can be used.

 [0092] The method of 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 peeled polyester film, or a heat conductive pressure-sensitive adhesive composition (F ), If necessary, between two exfoliated process papers, passing between rolls, and controlling the thickness through a die when extruding using an extruder, etc. Can be mentioned.

 In forming the sheet, it is desirable to apply pressure in order to make the thickness uniform. The pressurizing condition is usually lOMPa or less, preferably IMPa or less. Pressurization exceeding lOMPa is not preferable because the foamed cell may be crushed. The optimum pressing time may be selected in accordance with the temperature conditions and the type * amount of the polymerization initiator to be used, but it is preferably within 1 hour in consideration of productivity.

[0093] While conducting sheeting or after sheeting, for example, the heat conductive pressure-sensitive adhesive composition (F) is heated with hot air, an electric heater, infrared rays, or the like to thereby form a heat conductive pressure-sensitive adhesive sheet-like molded article. (G) can be suitably obtained. The heating temperature at this time was such that the organic peroxide thermal polymerization initiator (C2) and the thermally decomposable organic foaming agent (D) were efficiently decomposed, and the polymerization and heat of the (meth) acrylate monomer (A2m) Conditions under which the thermal decomposition of the degradable organic foaming agent (D) proceeds almost simultaneously are preferred. The temperature range varies depending on the types of the organic peroxide thermal polymerization initiator (C2) and the thermally decomposable organic foaming agent (D) to be used, but is preferably 100 ° C to 200 ° C.

 [0094] The heat conductive pressure-sensitive adhesive sheet-like molded body (G) is formed by molding a heat conductive pressure-sensitive adhesive composition (F) containing the heat-decomposable organic foaming agent (D) into a sheet shape. And by heating to a temperature not lower than 100 ° C and not higher than 200 ° C, the sheet of the heat conductive pressure-sensitive adhesive composition (F), polymerization of the (meth) acrylate monomer (A2m), And a sheet-like foamed molded article obtained by thermally decomposing the thermally decomposable organic foaming agent (D).

[0095] The heat-conductive pressure-sensitive adhesive sheet-like molded article (G) of the present invention is preferably a sheet-like foam-molded article, and the average diameter of the foamed cells is preferably 50 111 to 550 111, more preferably. Better Or 100 μm to 500 μm, more preferably 150 to 450 μm. The more the average diameter of the expanded senole is within the more preferable range, the better the pressure-sensitive adhesive retention.

[0096] The expansion ratio of the heat conductive pressure-sensitive adhesive sheet-like molded product (G) of the present invention is more preferably 1.01-1. 5 times, still more preferably 1.05-1. 4 times, particularly preferably. Is 1.:!~1.3 times

. The more the foaming ratio is in the above-mentioned preferable range, the better the pressure-sensitive adhesive retention.

 [0097] The heat conductive pressure-sensitive adhesive sheet-like molded product (G) of the present invention can be directly formed on a base material such as a heat radiator and provided as a part of an electronic component.

 Example

 [0098] Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, parts and percentages are by weight unless otherwise specified.

 In addition, the evaluation method of each characteristic of a (meth) acrylic acid ester copolymer, a heat conductive pressure sensitive adhesive composition (F), and a heat conductive pressure sensitive adhesive sheet-like molded product (G) is as follows.

[0099] (1) Weight average molecular weight (Mw) and number average molecular weight (Mn) of (meth) acrylic acid ester polymer (A1)

 Obtained in terms of standard polystyrene by gel permeation chromatography using tetrahydrofuran as a developing solvent.

[0100] (2) Average diameter of foamed cell of heat conductive pressure-sensitive adhesive sheet-shaped product (G)

 The surface of the heat conductive pressure-sensitive adhesive sheet-like molded body (G) is observed with a laser microscope, and the diameter of 100 foamed cells is measured to determine the average diameter.

[0101] (3) Foaming ratio of heat-conductive pressure-sensitive adhesive sheet-like molded product (G)

 The volume per unit weight of the foamed thermally conductive pressure-sensitive adhesive sheet-shaped product (G) is the volume per unit weight of the unfoamed thermally conductive pressure-sensitive adhesive sheet-shaped product (G) of the same composition. It is obtained by dividing.

[0102] (4) Hardness of heat conductive pressure-sensitive adhesive sheet-like molded product (G)

Measured by the Japan Rubber Association Standard (SRIS) Asker C method. The hardness meter uses “ASKER CL-150LJ” manufactured by Kobunshi Keiki Co., Ltd. Condition adjustment by stacking six test pieces of heat conductive pressure-sensitive adhesive sheet-shaped body (G) 30mm wide x 60mm long x 1mm thick and standing in a constant temperature room at 23 ° C for 48 hours or more Use the sample that has been subjected to Measure the hardness 20 seconds after bringing the damper into contact with the sampnore. Repeat the measurement 5 times, and use the average value as the test value.

[0103] (5) Thermal conductivity of heat-conductive pressure-sensitive adhesive sheet-like molded product (G)

 The heat-conductive pressure-sensitive adhesive sheet-like molded product (G) was cut into a size of 300 mm x 160 mm x 1 mm, and left in a constant temperature room at 23 ° C for 48 hours or more. The thermal conductivity measurement is performed by the unsteady hot wire comparison method using a rapid thermal conductivity meter (QTM-500: manufactured by Kyoto Electronics Industry Co., Ltd.). In addition, as a standard plate for comparison with known thermal conductivity, silicon sponge (0.1 WZm'K), silicon rubber (0.2W / m'K), quartz (1.4WZm'K), gino-reconia (3.4W) / m'K).

 [0104] (6) Pressure-sensitive adhesive retention of thermally conductive pressure-sensitive adhesive sheet-like molded product (G)

 Lay a 25mm x 25mm x lmm test piece on an aluminum plate, press it with a 2kg roller, and then press the glass plate on the other side. After standing for 1 hour, with the test piece in a vertical position, fix the aluminum plate to the wall, suspend a 500g weight on the glass plate, and place it in a constant temperature layer at 100 ° C. In this state, measure the time (holding time) until the weight falls. The longer the time, the better the pressure-sensitive adhesive retention.

 [0105] (7) Flame resistance

 Test in accordance with UL standard UL94 “Combustion test method for plastic materials for equipment parts”. Place a sheet-like sample in a cylinder, flame contact for 10 seconds, and immediately after afterflame combustion stops, perform flame contact for the second 10 seconds, and evaluate the test items shown in Table 1. Test five samples of the same sample type and classify the combustion classes shown in Table 1 based on the results.

[0106] [Table 1] UL94 V-0 UL94 V— 1 UL94 V- 2 Maximum after-flame burning time (* 1> 0 seconds ≤ 30 seconds ≤ 30 seconds After-flame combustion after the first and second flame contact

 ≤50 seconds ≤250 seconds ≤250 seconds Sum of time (* 2)

 Afterflame time and flamelessness after the second flame contact

 ≤30 seconds ≤ 60 seconds ≤ 60 seconds Maximum sum of baking times (* 3)

 Ignition of cotton by dripping No (* 4) No (* 4) Yes After flame until flame or flameless combustion No (* 4) No (* 4) No (* 4)

[0107] (Note to Table 1)

 * 1): The maximum value of the after flame burning time obtained for each sample for 5 samples

 * 2): Sum of after flame burning time obtained for each sample, total of 5 samples

 * 3): The maximum value for the five samples of the sum of afterflame time and flameless combustion time obtained for each sample.

 * 4): All five samples must be “None”

 [Example 1]

 In a reactor, 100 parts by weight of a monomer mixture consisting of 94% 2-ethylhexyl acrylate and 6% acrylic acid, 0.03 parts by weight of 2,2′-azobisisobutyronitrile and acetic acid 700 parts by weight of ethyl was added and dissolved uniformly. After purging with nitrogen, a polymerization reaction was carried out at 80 ° C. for 6 hours. The polymerization conversion rate was 97%. The resulting polymer was dried under reduced pressure to evaporate ethyl acetate to obtain a viscous solid (meth) acrylate polymer (Al) (1). The Mw of the (meth) acrylic acid ester polymer (Al) (1) was 270,000 and Mw / Mn was 3.1.

[0109] In a mortar for a grinder, (meth) acrylic acid ester polymer (Al) (1) 100 parts by weight, 2-ethylhexyl acrylate, 91 · 3%, methacrylolic acid 6.1%, and polyethylene glycol diester Metatalylate (Oxyethylene chain repeat number = 23, manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester 23G”) 2. (Meth) acrylate monomer mixture (A2m ') consisting of 6% (1) 32 weight 1,6 bis (t-butylperoxycarbonyloxy) hexane (hereinafter abbreviated as “tBCH”), which is an organic peroxide thermal polymerization initiator (C2). ° C. ] 1.0 part by weight, 4, 4'-oxybi which is a thermally decomposable organic foaming agent (D) (Benzenesulfonyl hydrazide) (hereinafter abbreviated as “OBSH”) (manufactured by Eiwa Chemical Industry Co., Ltd., trade name Neoselbon # 1000S) 0. 2 parts, expanded graphite powder (E) EC— 1 00 (Made by Ito Graphite Industries Co., Ltd.) 30 parts by weight and aluminum hydroxide which is a flame retardant thermally conductive inorganic compound (B) (made by Nippon Light Metal Co., Ltd., trade name: BF-083: average particle size = 8 μm) 220 parts by weight were charged in a lump and thoroughly mixed at room temperature with a crusher. Thereafter, the mixture was defoamed with stirring under reduced pressure to obtain a viscous liquid heat conductive pressure-sensitive adhesive composition (F) (1). A polyester film with a release agent is laid on the bottom of a 400 mm long, 400 mm wide, 2 mm deep mold, and then the heat conductive pressure sensitive adhesive composition (F) (1) is poured into the mold. Then, it was covered with a polyester film with a release agent. This is taken out of the mold, polymerized and foamed in a hot air oven at 155 ° C for 30 minutes, and covered with a polyester film with a release agent on both sides, a thermally conductive pressure-sensitive adhesive sheet that is a foam. A compact (G) (1) was obtained.

 [0110] The polymerization conversion rate of the (meth) acrylic acid ester monomer mixture (A2m ') was calculated from the amount of residual monomers in the sheet, and it was 99.9%.

 Each characteristic was evaluated about this heat conductive pressure-sensitive-adhesive sheet-like molded object (G) (1). The results are shown in Table 2.

 [0111] Further, except that OBSH, which is a thermally decomposable organic foaming agent (D), was not used, the same operation was performed in the same manner as described above, and both sides were covered with a polyester film with a release agent. A foamed thermally conductive pressure-sensitive adhesive sheet-like molded product (G) (1 ′) was obtained.

 Each characteristic of this heat conductive pressure-sensitive adhesive sheet-like molded product (G) (1 ') was also evaluated. The results are shown in Table 2.

[0112] (Comparative Example 1)

 Except for the use of expanded graphite powder (E), the same procedure as in Example 1 was carried out, and a heat-conductive pressure-sensitive adhesive sheet-like molding, which was a foam, covered on both sides with a polyester film with a release agent The body (G) (2) and the non-foamed thermally conductive pressure-sensitive adhesive sheet-like molded body (G) (2 ′) were obtained.

Each characteristic was evaluated for the heat conductive pressure-sensitive adhesive sheet-like molded product (G) (2) and the heat conductive pressure-sensitive adhesive sheet-like molded product (G) (2 '). The results are shown in Table 2. [0113] (Comparative Example 2)

 Instead of using 30 parts by weight of EC-100, which is expanded graphite powder (E), expanded graphite (not expanded graphite powder: only acid treatment is performed on graphite, and heat treatment is performed. SYZ R_ 501 (Sanyo Trading Co., Ltd.) was used in the same manner as in Example 1 except that 30 parts by weight of SYZ R_501 (Sanyo Trading Co., Ltd.) was used. The foam was covered with a polyester film with a release agent on both sides. A heat-conductive pressure-sensitive adhesive sheet-like molded product (G) (3) and a non-foamed heat-conductive pressure-sensitive adhesive sheet-like molded product (G) (3 ′) were obtained.

 Each characteristic of the heat conductive pressure-sensitive adhesive sheet-like molded product (G) (3) and the heat conductive pressure-sensitive adhesive sheet-like molded product (G) (3 ') was evaluated. The results are shown in Table 2.

 [0114] (Comparative Example 3)

 Instead of using 30 parts by weight of EC_100, which is expanded graphite powder (E), SPR-98 (made by Ito Graphite Industry Co., Ltd.), which is graphite (not expanded graphite powder), was used for 30 parts by weight. Otherwise, the same operation as in Example 1 was performed, and both sides were covered with a polyester film with a release agent, and the heat-conductive pressure-sensitive adhesive sheet-like molded body (G) (4) and unfoamed body, which are foams A heat conductive pressure-sensitive adhesive sheet-like molded product (G) (4 ′) was obtained.

 Each characteristic of the heat conductive pressure-sensitive adhesive sheet-like molded product (G) (4) and the heat conductive pressure-sensitive adhesive sheet-like molded product (G) (4 ′) was evaluated. The results are shown in Table 2.

[0115] [Table 2]

[0116] (Note to Table 2)

 * 1): Polyethylene glycol dimetatalylate

 * 2): 1,6_bis (t_butylperoxycarbonyloxy) hexane

 * 3): p, p'-oxybis (benzenesulfonylhydrazide)

[0117] From the results in Table 2, the following can be understood.

 (Meth) acrylic acid ester polymer (A1) 100 parts by weight, (Meth) acrylic acid ester monomer mixture (A2m ') 32 parts by weight, expanded graphite powder (E) 30 parts by weight, flame retardant thermally conductive inorganic Thermally conductive pressure-sensitive adhesive comprising 220 parts by weight of compound (B), organic peroxide thermal polymerization initiator (C2) 1.0 part by weight, and thermally decomposable organic foaming agent (D) 0.2 part The composition (F) is formed into a sheet and heated to form a sheet of the heat conductive pressure-sensitive adhesive composition (F), polymerization of the (meth) acrylate monomer mixture (A2m ′), Thermally decomposable organic foaming agent (D) (no foaming in (G) (1 ')) and thermally conductive pressure sensitive adhesive sheet with an average foam cell diameter of 200 μm In Example 1 where the molded body (G) (1) was prepared, a heat-conductive pressure-sensitive adhesive sheet-shaped molded body having good hardness, excellent pressure-sensitive adhesive retention, and thermal conductivity was obtained. Flame retardancy test results are, V- 2 becomes in UL- 94 flame retardant standards, showed flame retardant properties.

 [0118] Also, comparison is made between the thermally conductive pressure-sensitive adhesive sheet-like molded body (G) (1), which is a foam, and the thermally conductive pressure-sensitive adhesive sheet-shaped molded body (G) (1 '), which is an unfoamed body. As a result, the thermal conductivities were almost equal, and those using the expanded graphite powder showed the same thermal conductance in the foam as in the non-foam.

 On the other hand, in Comparative Example 1 in which the expanded graphite powder (E) was not used, although it had flame retardancy, it was inferior in thermal conductivity, particularly in a foam.

 In Comparative Example 2 in which expanded graphite was used instead of expanded graphite powder (E), although it had flame retardancy, it was inferior in thermal conductivity.

 In Comparative Example 3 using graphite instead of the expanded graphite powder (E), although it has flame retardancy, it was inferior in thermal conductivity, particularly in the foam.

Industrial applicability The heat conductive pressure-sensitive adhesive sheet-like molded product of the present invention has good flame retardancy, hardness and heat conductivity, and is excellent in the balance of these properties.

 Therefore, this heat conductive pressure-sensitive adhesive sheet-like molded product is a plasma display panel (

It is particularly useful as a heat conduction sheet for efficiently conducting heat from a heat generating body to a heat radiating body such as an electronic component (PDP).

Claims

The scope of the claims

 [1] An adhesive and / or tacky composition (S) containing at least one selected from the group consisting of rubber, elastomer and resin as a main component, a flame retardant thermally conductive inorganic compound (B) and A heat conductive pressure-sensitive adhesive composition (F) comprising the expanded graphite powder (E).

[2] The heat conductive pressure-sensitive adhesive composition (F) according to claim 1, wherein the primary average particle diameter of the expanded graphite powder (E) is 5 to 500 μm.

[3] Expanded graphite powder (E) was obtained through a process including heat treatment of acid-treated graphite at 500 to 1200 ° C to expand to 100 to 300 ml / g, and then powdering The heat conductive pressure-sensitive adhesive composition (F) according to claim 1, wherein the heat conductive pressure-sensitive adhesive composition is (F).

[4] The heat conductive pressure-sensitive adhesive composition (F) according to claim 1, wherein the flame retardant heat conductive inorganic compound (B) is aluminum hydroxide.

[5] The heat conductive pressure-sensitive adhesive composition (F) according to claim 1, wherein the composition (S) contains a (meth) acrylic acid ester polymer (A1) as a main component.

[6] The composition (S) force The heat conductive pressure-sensitive adhesive composition (F) according to claim 5, further comprising a (meth) acrylic acid ester monomer (A2m).

[7] The heat conductive pressure-sensitive adhesive composition (F) according to claim 6, further comprising an organic peroxide thermal polymerization initiator (C2).

[8] (Meth) acrylic acid ester polymer (A1) 100 parts by weight, (meth) acrylic acid ester monomer

 (A2m) 25 to 100 parts by weight, expanded graphite powder (E) 5 to 100 parts by weight, flame retardant thermally conductive inorganic compound (B) 100 to 450 parts by weight and organic peroxide thermal polymerization initiator (C2 0.1-: The thermally conductive pressure-sensitive adhesive composition (F) according to any one of claims 5 to 7, comprising 10 parts by weight.

 [9] (Meth) acrylic acid ester polymer (A1) force (meth) acrylic acid ester monomer unit (al) that forms a homopolymer with a glass transition temperature of -20 ° C or lower (al) 80-99. The heat conductive pressure-sensitive adhesive composition (F) according to claim 8, comprising 9% by weight and 20 to 0.1% by weight of a monomer unit (a2) having an organic acid group.

[10] Claims in which the weight average molecular weight (Mw) of the (meth) acrylic acid ester polymer (A1) is in the range of 100,000 to 400,000 as measured by gel permeation chromatography (GPC method). 9. The heat conductive pressure-sensitive adhesive composition (F) according to item 8.

[11] (Meth) acrylate monomer (A2m) forms a homopolymer with a glass transition temperature of -20 ° C or less (meth) acrylate monomer (a5m) 70-99 9. A (meth) acrylic acid ester monomer mixture (A2m ′) comprising 9% by weight and 30 to 0.1% by weight of a monomer (a6m) having an organic acid group. Thermally conductive pressure sensitive adhesive composition (F).

 [12] The thermally conductive pressure-sensitive adhesive composition (F) according to claim 8, further comprising 0.01 to 0.8 parts by weight of a thermally decomposable organic foaming agent (D).

[13] Claims: A heat-conductive pressure-sensitive adhesive sheet-shaped product (G) obtained by forming the heat-conductive pressure-sensitive adhesive composition (F) according to any of claims 5 to 5 into a sheet shape.

[14] The heat conductive pressure-sensitive adhesive sheet-like molded product according to claim 13, which is formed by casting (G)

[15] The heat conductive pressure-sensitive adhesive composition (F) according to any one of claims 7 to 12 is formed into a sheet and heated to (meth) acrylate monomer mixture (A2m ) Is a heat conductive pressure-sensitive adhesive sheet-like molded product (G).

 [16] The heat conductive pressure-sensitive adhesive sheet-like molded article (G) according to any one of claims 13 to 15, wherein the foam is foamed.

 [17] The heat conductive pressure-sensitive adhesive sheet-like molded article (G) according to claim 16, which has foam cells having an average diameter of 50 μm to 550 μm.

[18] The heat conductive pressure-sensitive adhesive sheet-like molded article (G) according to claim 16 or 17, wherein the expansion ratio is 1.01 to 1.5.