JP5665268B2 - Heat conduction sheet - Google Patents

Description

  The present invention relates to a heat conductive sheet used for efficiently radiating heat generated from semiconductor elements such as an IC, a CPU, and an LED on an electronic board inside an electric device and an electronic device to the outside.

  Conventionally, with the spread of digital home appliances, there is an increasing demand for higher speed and higher functionality of electrical components and electronic devices. However, in these electronic components and electronic devices, electronic elements such as LSIs and CPUs that perform electronic control have increased power consumption due to an increase in the degree of integration of computers and an increase in operation speed. Heat dissipation measures are indispensable because they have problems such as device defects. For heat dissipation in general electronic equipment, a heat sink or the like is attached, and the heat sink is forcibly cooled by a cooling fan or the like. Small devices such as notebook personal computers and electronic parts mounted with high density have restrictions such as a small space for installing a cooling fan, etc., and measures against heat dissipation are taken by applying silicone grease. It was. In addition, in order to meet the demand for higher performance of electronic components, cases using heat conductive sheets are increasing. When a cooling component such as a heat sink is attached to a heating element, the heat conductive sheet is used for the purpose of effectively transferring heat to the cooling component by close contact between the two.

At present, a heat conductive sheet in which silicone rubber is mixed with a filler having a relatively high heat conductivity is mainly used as the heat conductive sheet. This silicone rubber heat conductive sheet is easy to handle. However, the heat conduction sheet made of silicone rubber has a problem that the number of steps increases because the silicone resin itself as a raw material is expensive and a curing step is essential. Further, since the low molecular siloxane is contained in the silicone resin, a low molecular siloxane gas is generated when the silicone resin is used by being attached to a heating element. The gas can adhere to the electrode contacts and produce silicon dioxide, which can cause contact failure.
In addition, in order to take good heat dissipation measures, it is required that the heating element and the cooling parts such as the heat sink are in close contact with each other, and a heat conduction sheet provided with an adhesive layer is used to take better heat dissipation measures. It has been. However, since the heat conductivity of the adhesive layer is inferior, the heat transfer capability of the heat conducting sheet is not sufficiently exhibited, and the heat dissipation efficiency may be inferior.
As a solution to the above problem, a heat conductive sheet having an adhesive layer made of an adhesive containing a heat conductive filler is known (see Patent Document 1).

JP 2007-111943 A

However, in the heat conductive sheet described in Patent Document 1, the adhesion is improved by increasing the thickness of the adhesive layer. In this case, in the step of attaching the sheet to a cooling component such as a heating element or a heat sink, When the sheet is re-applied for reasons such as misalignment of the attaching position, generation of wrinkles, etc., the adhesive strength is too strong and the sheet may be damaged, resulting in poor sheet attaching workability.
Furthermore, the heat conductive sheet is required to have flame retardancy from the viewpoint of safety etc. in electrical parts and electronic equipment, but the adhesive material constituting the adhesive layer is generally inferior in flame retardancy. It is difficult to maintain the flame retardancy of the provided heat conductive sheet.

  The present invention was made in order to solve the problems of the above-described heat conductive sheet, maintains excellent heat conductivity and flame retardancy, and further has good workability for sheet pasting. It is a problem to provide.

  As a result of intensive studies to solve the above problems, the present inventors have a heat conductive layer made of a specific resin composition and an adhesive layer made of a specific resin formed on at least one surface of the heat conductive layer. And it discovered that the said subject could be solved by controlling the thickness of this adhesion layer to a fixed range, and completed this invention.

That is, the present invention is as follows.
[1]
(A) Styrenic thermoplastic elastomer 5 to 25% by mass,
(B) 1-20% by mass of a softener for rubber, and (C) 70-94% by mass of a metal hydroxide,
A heat conductive layer comprising a heat conductive resin composition containing
A heat conductive sheet having (D) an adhesive layer made of an acrylic adhesive formed on at least one side of the heat conductive layer,
The heat conductive sheet whose thickness of the said adhesion layer is 1 micrometer or more and less than 10 micrometers.
[2]
The heat conductive sheet according to the above [1], wherein the component (D) further contains a flame retardant.
[3]
The said flame retardant is a heat conductive sheet of the said [2] description which is a 1 type, or 2 or more types of mixture chosen from phosphate ester.
[4]
The heat conductive sheet according to any one of [1] to [3], wherein the component (C) is aluminum hydroxide.
[5]
The said (A) component is a heat conductive sheet in any one of said [1]-[4] which is a copolymer of a conjugated diene and a vinyl aromatic compound.
[6]
The component (A) is a hydrogenated copolymer and / or a modified hydrogenated copolymer obtained by adding hydrogen to a copolymer of a conjugated diene and a vinyl aromatic compound. 5].
[7]
The heat conductive sheet according to [5] or [6] above, wherein the content of the vinyl aromatic compound unit in the copolymer of the conjugated diene and the vinyl aromatic compound is 30% by mass or more and 90% by mass or less.
[8]
The heat conductive sheet according to any one of the above [5] to [7], wherein the content of a polymer block comprising a vinyl aromatic compound of a copolymer of the conjugated diene and a vinyl aromatic compound is 40% by mass or less. .
[9]
The heat conductive sheet according to any one of the above [5] to [8], wherein the copolymer of the conjugated diene and the vinyl aromatic compound has a weight average molecular weight of 5 × 10 ^{4 to} 100 × 10 ⁴ .
[10]
The heat conductive sheet according to any one of the above [6] to [9], wherein the hydrogenation rate of double bonds based on the conjugated diene of the hydrogenated copolymer and / or modified hydrogenated copolymer is 10% or more. .
[11]
The heat conductive sheet according to any one of [1] to [10], wherein the heat conductivity is 1.0 W / m · K or more.

  According to the present invention, it is possible to provide a heat conductive sheet that is excellent in heat conductivity and flame retardancy, and further has good workability in sheet pasting.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as the present embodiment) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

The heat conductive sheet of the present embodiment is
(A) Styrenic thermoplastic elastomer 5 to 25% by mass,
(B) 1-20% by mass of a softener for rubber, and (C) 70-94% by mass of a metal hydroxide,
A heat conductive layer comprising a heat conductive resin composition containing
(D) an adhesive layer made of an acrylic adhesive formed on at least one side of the heat conductive layer;
A heat conductive sheet having
The adhesive layer has a thickness of 1 μm or more and less than 10 μm.

  The (A) styrenic thermoplastic elastomer contained in the heat conductive resin composition forming the heat conductive layer adheres well to an adherend having a large surface shape over a wide area by plastic deformation, and has excellent heat conductivity. From the viewpoint of exhibiting the above, it is preferable to use a material exhibiting plastic deformability.

  Content of (A) styrene-type thermoplastic elastomer contained in the heat conductive resin composition of this Embodiment is 5-25 mass%, Preferably it is 5-20 mass%, More preferably, it is 8-20 mass%. It is. (A) When the content of the styrenic thermoplastic elastomer is less than 5% by mass, sufficient moldability cannot be obtained, and as a result, a heat conductive sheet that can achieve the object of the present invention cannot be obtained, and 25% by mass. When it exceeds%, thermal conductivity and flame retardancy tend to decrease.

  (A) It does not specifically limit as a styrene-type thermoplastic elastomer, A well-known thing can be used. Specifically, for example, SBS (styrene-butadiene-styrene block copolymer), SIS (styrene-isoprene-styrene block copolymer), SEBS (styrene-ethylene-butadiene-styrene block copolymer), SEPS ( And a copolymer of a conjugated diene such as a styrene-ethylene-propylene-styrene block copolymer) and a vinyl aromatic compound. Copolymers of conjugated dienes and vinyl aromatic compounds include both hydrogenated and non-hydrogenated copolymers. Preferably, hydrogenated copolymers and / or modified hydrogenated copolymers obtained by adding hydrogen are used. More preferably, it is a hydrogenated copolymer and / or a modified hydrogenated copolymer containing a random copolymer of styrene-butadiene.

  Here, the conjugated diene is a diolefin having a pair of conjugated double bonds. Specifically, for example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1, Examples include 3-pentadiene and 1,3-hexadiene, and 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene) are preferable. These may be used alone or in combination of two or more.

  Examples of the vinyl aromatic compound include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p. -Aminoethyl styrene etc. are mentioned. These may be used alone or in combination of two or more.

  The content of the vinyl aromatic compound unit in the copolymer of the conjugated diene and the vinyl aromatic compound is preferably 30% by mass to 90% by mass, more preferably 45% by mass to 90% by mass, and still more preferably. It is 45 mass% or more and 86 mass% or less. If content of a vinyl aromatic compound unit is the said range, it exists in the tendency for the heat conductive resin composition which is rich in a softness | flexibility and excellent in the bending resistance etc. to be obtained. Here, the content of the vinyl aromatic compound unit can be measured using a nuclear magnetic resonance apparatus (NMR) or the like.

  The copolymer of the conjugated diene and the vinyl aromatic compound preferably has a content of a polymer block composed of the vinyl aromatic compound of 40% by mass or less. When the content of the polymer block made of a vinyl aromatic compound is within the above range, a heat conductive resin composition having good flexibility and blocking resistance tends to be obtained.

  From the viewpoint of obtaining a copolymer of a conjugated diene and a vinyl aromatic compound excellent in blocking resistance, the content of the polymer block made of a vinyl aromatic compound is more preferably 10 to 40% by mass, still more preferably. It is 13-37 mass%, Most preferably, it is 15-35 mass%.

  From the viewpoint of obtaining a copolymer of a conjugated diene and a vinyl aromatic compound excellent in flexibility, the content of the polymer block comprising the vinyl aromatic compound is preferably less than 10% by mass, more preferably 8% by mass. Less than, more preferably less than 5% by mass.

The content of the polymer block composed of a vinyl aromatic compound is, for example, a method of oxidatively decomposing a copolymer before hydrogenation with tertiary butyl hydroperoxide using osmium tetroxide as a catalyst (IM KOLTHOFF, et al., J. Polym.Sci.1, 429 (1946)) The mass of the polymer block component comprising a vinyl aromatic compound (excluding vinyl aromatic polymer components having an average degree of polymerization of about 30 or less). Can be obtained from the following equation.
Content (% by mass) of polymer block composed of vinyl aromatic compound = {(mass of polymer block composed of vinyl aromatic compound in copolymer of conjugated diene and vinyl aromatic compound) / (conjugated diene and vinyl Mass of aromatic copolymer)} × 100

  The block ratio of the vinyl aromatic compound in the copolymer of conjugated diene and vinyl aromatic compound is preferably 40% by mass or less, more preferably 20% by mass or less, and still more preferably 18% by mass or less. Here, the block ratio of a vinyl aromatic compound means the ratio of the block amount of a polymer composed of a vinyl aromatic compound to the total vinyl aromatic compound amount of a copolymer of a conjugated diene and a vinyl aromatic compound. When the block ratio is within the above range, a heat-conductive resin composition having good flexibility tends to be obtained.

  The copolymer of the conjugated diene and the vinyl aromatic compound preferably contains 5% by mass or more of vinyl aromatic compound units in addition to the polymer block made of the vinyl aromatic compound. When the content of the vinyl aromatic unit other than the polymer block composed of the vinyl aromatic compound is 5% by mass or more, the heat resistance of the copolymer of the conjugated diene and the vinyl aromatic tends to be improved. Further, crystallization of portions other than the polymer block made of a vinyl aromatic compound can be inhibited, and the flexibility tends to be good. Furthermore, since a large amount of filler can be blended, the thermal conductivity tends to be good.

The weight average molecular weight of the copolymer of conjugated diene and vinyl aromatic compound is preferably 5 × 10 ^{4 to} 100 × 10 ⁴ , more preferably 8 × 10 ⁴ to 80 × 10 ⁴ , and even more preferably 9 ×. 10 ⁴ to 30 × 10 ⁴ . When using a copolymer of a conjugated diene and a vinyl aromatic compound having a polymer block content of a vinyl aromatic compound of 10 to 40% by mass, the weight average molecular weight is preferably 10 × 10 ⁴ to 50 ×. 10 ⁴ , more preferably 13 × 10 ⁴ to 40 × 10 ⁴ , and still more preferably 15 × 10 ⁴ to 30 × 10 ⁴ . When the weight average molecular weight is 5 × 10 ⁴ or more, the toughness tends to be good, and when it is 100 × 10 ⁴ or less, the flexibility tends to be good. Furthermore, when the weight average molecular weight is 5 × 10 ^{4 to} 100 × 10 ⁴ , the content of low molecular weight components is small, and thus volatile components tend to decrease.

  The molecular weight distribution (Mw / Mn) (ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn)) of the copolymer of the conjugated diene and the vinyl aromatic compound is 1.01 to 1.05 from the viewpoint of molding processability. It is preferable that it is 8.0, More preferably, it is 1.1-6.0, More preferably, it is 1.1-5.0.

  The shape of the molecular weight distribution measured by gel permeation chromatography (GPC) is not particularly limited, and may have a polymodal molecular weight distribution having two or more peaks (peaks). Preferably, it has a monomodal molecular weight distribution.

  Here, the molecular weight of the copolymer of conjugated diene and vinyl aromatic compound is measured by gel permeation chromatography (GPC), and the peak obtained from the chromatogram is obtained from the measurement of commercially available standard polystyrene. The weight average molecular weight determined using a standard curve (created using the peak molecular weight of standard polystyrene). Similarly, the molecular weight distribution of the copolymer of conjugated diene and vinyl aromatic can also be determined from the measurement by GPC.

  The hydrogenated copolymer and modified hydrogenated copolymer obtained by adding hydrogen to a copolymer of conjugated diene and vinyl aromatic are each a double bond based on the conjugated diene in the copolymer before hydrogenation. Is preferably 10% or more, more preferably 75% or more, and still more preferably 85% or more. When the hydrogenation rate is 10% or more, the flexibility, strength, and elongation due to thermal deterioration do not decrease, and good heat resistance tends to be exhibited. From the viewpoint of obtaining a heat dissipation material having excellent heat resistance, the hydrogenation rate is preferably 85% or more, more preferably 90% or more, and still more preferably 95% or more. From the viewpoint of obtaining a heat dissipation material having excellent weather resistance, the hydrogenation rate is preferably 75% or more, more preferably 85% or more, and still more preferably 90% or more. In addition, when the copolymer is crosslinked, the hydrogenation rate is preferably 98% or less, more preferably 95% or less, and still more preferably 90% or less.

  Here, the hydrogenation rate of the double bond based on the conjugated diene is a hydrogenated copolymer with respect to the double bond of the conjugated diene contained in each of the copolymer before hydrogenation and the copolymer before modification hydrogenation. And the ratio of each hydrogenated double bond of the modified hydrogenated copolymer.

  The hydrogenation rate of the hydrogenated copolymer and the modified hydrogenated copolymer can be measured using a nuclear magnetic resonance apparatus (NMR) or the like.

  The hydrogenation rate of the aromatic double bond based on the vinyl aromatic compound in the copolymer is not particularly limited, but is preferably 50% or less, more preferably 30% or less, and still more preferably 20% or less. is there.

It is particularly preferable that the copolymer of the conjugated diene and the vinyl aromatic compound has at least one structure selected from the following general formulas (i) to (v). Moreover, the mixture which contains two or more of the following structures in arbitrary ratios may be sufficient.
(I) b
(Ii) ba
(Iii) b-a-b
(Iv) (ba) _m -Z
(V) (b−a) _n −Z−a _p
(Here, b is a random copolymer block of conjugated diene and vinyl aromatic compound (hereinafter referred to as block b), and a is a vinyl aromatic polymer block (hereinafter referred to as block a). m is an integer greater than or equal to 2, n and p are each an integer greater than or equal to 1. Z shows a coupling agent residue.)

  In the above general formula, the vinyl aromatic compounds in the block b may be distributed uniformly or in a tapered shape. The block b may include a plurality of portions where the vinyl aromatic compound is uniformly distributed and / or a portion where the vinyl aromatic compound is distributed in a tapered shape. M is 2 or more, preferably an integer of 2 to 10, and n and p are each 1 or more, preferably an integer of 1 to 10. By making the block b into a random structure of a conjugated diene and a vinyl aromatic compound, the crystal portion in the copolymer can be reduced or eliminated as much as possible, and a large amount of filler can be mixed.

  In the present embodiment, the modified hydrogenated copolymer refers to a copolymer having a functional group in a polymer chain. Examples of the functional group include a hydroxyl group, a carboxyl group, a carbonyl group, a thiocarbonyl group, an acid halide group, an acid anhydride group, a carboxylic acid group, a thiocarboxylic acid group, an aldehyde group, a thioaldehyde group, a carboxylic acid ester group, and an epoxy. Group, thioepoxy group, sulfide group, isocyanate group, isothiocyanate group, amide group, sulfonic acid group, sulfonic acid ester group, phosphoric acid group, phosphoric acid ester group, amino group, imino group, nitrile group, pyridyl group, quinoline group , Functional groups selected from silicon halide groups, silanol groups, alkoxysilane groups, tin halide groups, alkoxytin groups, and phenyltin groups. The modified hydrogenated copolymer preferably has at least one functional group selected from a hydroxyl group, an amino group, an epoxy group, a silanol group, and an alkoxysilane group, more preferably a hydroxyl group, an amino group, and an epoxy group. Having at least one functional group selected from

  The modified hydrogenated copolymer can be obtained, for example, by reacting a modifier containing these functional groups at the end of polymerization of the copolymer.

  In the present embodiment, as a modifier used to obtain a modified hydrogenated copolymer having at least one functional group selected from a hydroxyl group, an epoxy group, an amino group, a silanol group, and an alkoxysilane group, for example, The modifier described in JP-B-4-39495 can be used.

  The modified hydrogenated copolymer can be obtained, for example, by subjecting a living end of a copolymer before hydrogenation obtained using an organolithium compound as a polymerization catalyst to an addition reaction of a modifier containing a functional group and adding hydrogen thereto. Can do.

  Other methods for obtaining a modified hydrogenated copolymer include, for example, reacting an organic alkali metal compound such as an organic lithium compound (metalation reaction) with the hydrogenated copolymer, and then adding the organic alkali metal to the copolymer. Examples thereof include a method of subjecting a modifier containing a functional group to an addition reaction.

  The hydrogenated copolymer and / or modified hydrogenated copolymer preferably has substantially no crystallization peak in the temperature range of −50 to 100 ° C. in the differential scanning calorimetry (DSC method). Here, substantially no crystallization peak exists in the temperature range of −50 to 100 ° C. when no peak due to crystallization appears in this temperature range or when a peak due to crystallization is observed. Means that the crystallization peak heat quantity in the crystallization is less than 3 J / g. By reducing or eliminating the crystal part as much as possible, it becomes possible to mix a large amount of the filler. This is because the filler cannot penetrate into the crystal part.

  At least one of the loss tangent (tan δ) peaks in the dynamic viscoelastic spectrum of the hydrogenated copolymer and / or modified hydrogenated copolymer is preferably present at −30 to 80 ° C., more preferably. -20 to 70 ° C, more preferably -20 to 50 ° C. The peak of tan δ existing in the range of −30 to 80 ° C. is a peak due to the block B. When at least one tan δ peak exists in the range of −30 to 80 ° C., both flexibility and toughness tend to be excellent.

  The microstructure of the conjugated diene portion of the copolymer of conjugated diene and vinyl aromatic compound (ratio of cis, trans, vinyl) can be arbitrarily changed by using a polar compound or the like described later, and is not particularly limited. Generally, when 1,3-butadiene is used as the conjugated diene, the 1,2-vinyl bond content is 5 to 80%, preferably 10 to 60%, based on 100% of the conjugated diene moiety. When isoprene is used as the conjugated diene or when 1,3-butadiene and isoprene are used in combination, the total content of 1,2-vinyl bonds and 3,4-vinyl bonds is preferably 3-75%, more preferably Is 5 to 60%. In this embodiment, the total content of 1,2-vinyl bond and 3,4-vinyl bond (however, when 1,3-butadiene is used as the conjugated diene, 1,2-vinyl bond is used. Content) is hereinafter referred to as vinyl bond content.

  The vinyl bond content based on the conjugated diene of the copolymer of conjugated diene and vinyl aromatic compound can be measured using a nuclear magnetic resonance apparatus (NMR).

  The difference between the maximum value and the minimum value of the vinyl bond content in each molecular chain in the copolymer of conjugated diene and vinyl aromatic compound is preferably less than 10%, more preferably 8% or less, Preferably it is 6% or less. The vinyl bonds in the copolymer chain may be distributed uniformly or in a tapered shape. Here, the difference between the maximum value and the minimum value of the vinyl bond content is the maximum and minimum values of the vinyl bond content determined by the polymerization conditions, that is, the type, amount and polymerization temperature of the vinyl bond content modifier. Is the difference.

  The difference between the maximum value and the minimum value of the vinyl bond content in the conjugated diene polymer chain can be controlled by, for example, the polymerization temperature during the polymerization of the conjugated diene or the copolymerization of the conjugated diene and the vinyl aromatic compound. . When the type and amount of a vinyl bond amount modifier such as a tertiary amine compound or an ether compound is constant, the vinyl bond content incorporated into the polymer chain during polymerization is determined by the polymerization temperature. Therefore, a polymer polymerized isothermally becomes a polymer in which vinyl bonds are uniformly dispersed. In contrast, polymers polymerized at elevated temperatures have a high vinyl bond content at the initial stage (polymerization at low temperatures) and a low vinyl bond content at the second half (polymerization at high temperatures). It becomes a polymer with a difference. By adding hydrogen to the copolymer having such a structure, a hydrogenated copolymer and a modified hydrogenated copolymer having a difference in vinyl bond content in each molecular chain can be obtained.

  In the present embodiment, the pre-hydrogenated copolymer of a conjugated diene and a vinyl aromatic compound can be obtained by anionic living polymerization using an initiator such as an organic alkali metal compound in a hydrocarbon solvent, for example. Examples of the hydrocarbon solvent include aliphatic hydrocarbons such as n-butane, isobutane, n-pentane, n-hexane, n-heptane, and n-octane, and fats such as cyclohexane, cycloheptane, and methylcycloheptane. Examples thereof include cyclic hydrocarbons, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene.

  In addition, as the initiator, an aliphatic hydrocarbon alkali metal compound, an aromatic hydrocarbon alkali metal compound, an organic amino alkali, which are generally known to have anionic polymerization activity with respect to a conjugated diene and a vinyl aromatic compound. A metal compound etc. are mentioned. Examples of the alkali metal contained in the initiator include lithium, sodium, and potassium. Suitable organic alkali metal compounds are aliphatic and aromatic hydrocarbon lithium compounds having 1 to 20 carbon atoms, a compound containing one lithium in one molecule, a dilithium compound containing a plurality of lithiums in one molecule, Examples include trilithium compounds and tetralithium compounds.

  Specific examples of the initiator include n-propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n-pentyl lithium, n-hexyl lithium, benzyl lithium, phenyl lithium, tolyl lithium, di- Examples include a reaction product of isopropenylbenzene and sec-butyllithium, and a reaction product of divinylbenzene, sec-butyllithium and a small amount of 1,3-butadiene. Further, 1- (t-butoxy) propyllithium disclosed in US Pat. No. 5,708,092 and a lithium compound in which 1 to several molecules of isoprene monomer are inserted to improve its solubility, British Patent 2 Siloxy group-containing alkyllithium such as 1- (t-butyldimethylsiloxy) hexyllithium disclosed in US Pat. No. 5,241,239, amino group-containing alkyl disclosed in US Pat. No. 5,527,753 Aminolithiums such as lithium, diisopropylamid lithium and hexamethyldisilazide lithium can also be used.

  In the present embodiment, when an organic alkali metal compound is used as a polymerization initiator and a conjugated diene and a vinyl aromatic compound are copolymerized, a vinyl bond (1, 2 bond or 3, 3) derived from the conjugated diene incorporated in the polymer is used. In order to adjust the content of (4 bonds) and the random copolymerizability between the conjugated diene and the vinyl aromatic compound, a tertiary amine compound or an ether compound can be added as a regulator.

  In the present embodiment, the method of copolymerizing a conjugated diene and a vinyl aromatic compound using an organic alkali metal compound as a polymerization initiator may be batch polymerization, continuous polymerization, or a combination thereof. . In particular, the continuous polymerization method is preferable from the viewpoint of adjusting the molecular weight distribution to a preferable appropriate range. The polymerization temperature is usually 0 ° C to 180 ° C, preferably 30 ° C to 150 ° C. The time required for the polymerization varies depending on the conditions, but is usually within 48 hours, preferably 0.1 to 10 hours. Moreover, it is preferable to superpose | polymerize in inert gas atmosphere, such as nitrogen gas. The polymerization pressure is not particularly limited as long as it is carried out within a range of pressure sufficient to maintain the monomer and solvent in the liquid phase within the above polymerization temperature range. Furthermore, care must be taken so that impurities that inactivate the catalyst and living polymer, for example, water, oxygen, carbon dioxide, etc., do not enter the polymerization system.

  Moreover, a coupling reaction can be performed by adding a necessary amount of a coupling agent having two or more functional groups at the end of the polymerization. A known bifunctional coupling agent can be used without any particular limitation. Specific examples include dihalogen compounds such as dimethyldichlorosilane and dimethyldibromosilane, and acid esters such as methyl benzoate, ethyl benzoate, phenyl benzoate, and phthalates.

Moreover, a well-known thing can be used as a polyfunctional coupling agent more than trifunctional group, It does not specifically limit. Specifically, for example, polyalcohols having three or more valences, polyepoxy compounds such as epoxidized soybean oil, diglycidyl bisphenol A, general formula R _4-n SiX _n (where R is 1 to 20 carbon atoms) And a halogenated silicon compound and a halogenated tin compound represented by 3 or 4). Examples of the silicon halide compound include methylsilyl trichloride, t-butylsilyl trichloride, silicon tetrachloride and bromides thereof. Examples of the halogenated tin compound include methyltin trichloride, t-butyltin trichloride, tetrachloride. And polyvalent halogen compounds such as tin chloride. Moreover, dimethyl carbonate, diethyl carbonate, etc. can also be used.

The hydrogenation catalyst used for producing the hydrogenated copolymer and the modified hydrogenated copolymer is not particularly limited, and the following catalysts conventionally known can be used.
(1) A supported heterogeneous hydrogenation catalyst in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, diatomaceous earth, or the like,
(2) a so-called Ziegler type hydrogenation catalyst using an organic acid salt such as Ni, Co, Fe, Cr, or a transition metal salt such as acetylacetone salt and a reducing agent such as organic aluminum, and (3) Ti, Ru, Rh Homogeneous hydrogenation catalysts such as so-called organometallic complexes such as organometallic compounds such as Zr.

  Specific examples of the hydrogenation catalyst include Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, Japanese Patent Publication No. 63-4841, Japanese Patent Publication No. 1-337970, and Japanese Patent Publication No. 1-35381. The hydrogenation catalyst described in JP-B-2-9041 and the like can be used.

  Preferred hydrogenation catalysts include mixtures with titanocene compounds and / or reducing organometallic compounds. As the titanocene compound, for example, a compound described in JP-A-8-109219 can be used. Specifically, biscyclopentadienyl titanium dichloride, monopentamethylcyclopentadienyl titanium trichloride, and the like can be used. (Substituted) The compound which has at least 1 or more the ligand which has a cyclopentadienyl structure, an indenyl structure, and a fluorenyl structure is mentioned. Examples of the reducing organometallic compound include organic alkali metal compounds such as organolithium, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.

  The hydrogenation reaction is usually performed in a temperature range of 0 to 200 ° C, preferably 30 to 150 ° C. The pressure of hydrogen used for the hydrogenation reaction is preferably 0.1 to 15 MPa, more preferably 0.2 to 10 MPa, and still more preferably 0.3 to 5 MPa. The hydrogenation reaction time is usually 3 minutes to 10 hours, preferably 10 minutes to 5 hours. The hydrogenation reaction can be any of a batch process, a continuous process, or a combination thereof.

  In the reaction solution after the hydrogenation reaction, the catalyst residue can be removed if necessary, and the hydrogenated copolymer and the modified hydrogenated copolymer can be separated from the solvent. Examples of the separation method include, for example, a method in which a polar solvent that is a poor solvent for a polymer such as acetone or alcohol is added to the solution after the hydrogenation reaction to precipitate and recover the polymer, a hydrogenated copolymer And a method of charging the solution of the modified hydrogenated copolymer into hot water with stirring and removing the solvent by steam stripping, or a method of directly heating the polymer solution and distilling off the solvent. be able to.

  Stabilizers such as various phenol stabilizers, phosphorus stabilizers, sulfur stabilizers and amine stabilizers can be added to the hydrogenated copolymer and the modified hydrogenated copolymer.

  The (B) rubber softener contained in the heat conductive resin composition forming the heat conductive layer is not particularly limited, and a known one can be used. Specific examples include silicone oil, synthetic oil, fluorine oil, mineral oil (petroleum oil), and synthetic oil. Examples of oils that are preferable as rubber softeners include paraffinic, naphthenic, aromatic, and the like, and more preferable examples include paraffinic and naphthenic. Aromatic oils may adversely affect cold resistance and durability. Among these, paraffinic oil is particularly preferable, and paraffinic oil having a small aromatic ring component is particularly preferable.

Kinematic viscosity at 40 ° C. of paraffin oil is preferably 100 mm ² / sec or more, more preferably 100~10000mm ² / sec, more preferably 200~5000mm ² / sec. Examples of the paraffin oil include “NA Solvent (trade name)” manufactured by Nippon Oil & Fat Co., Ltd., “Diana (registered trademark) process oil PW-90, PW-380” manufactured by Idemitsu Kosan Co., Ltd., “manufactured by Idemitsu Petrochemical Co., Ltd.” IP-solvent 2835 (trade name) "," Neothiozol (trade name) "manufactured by Sanko Chemical Co., Ltd. and the like.

  (B) The rubber softener preferably has a flash point of 170 to 300 ° C. and a weight average molecular weight of 100 to 5000.

  (B) Content of the softening agent for rubber | gum is 1-20 mass% with respect to the heat conductive resin composition whole quantity, Preferably it is 2-15 mass%, More preferably, it is 6-12 mass%. When the content of the rubber softener exceeds 20% by mass, the rubber softener tends to bleed out, and the flame retardancy tends to decrease. Moreover, when the content of the softening agent for rubber is less than 1% by mass, it becomes difficult to obtain the flexibility required for the resin composition.

  (C) The metal hydroxide contained in the heat conductive resin composition which forms a heat conductive layer does not have a restriction | limiting in particular, A well-known thing can be used. Specifically, it is preferably one or a mixture of two or more selected from aluminum hydroxide, magnesium hydroxide, and zinc hydroxide. In particular, aluminum hydroxide is more preferable because it is a flame retardant and acts as a thermally conductive filler. The endothermic amount of aluminum hydroxide is about 1.97 kJ / g, which is a large value compared to about 1.31 kJ / g of magnesium hydroxide and about 0.93 kJ / g of calcium hydroxide. It has the feature of being high.

  (C) Content of a metal hydroxide is 70-94 mass% or less with respect to the heat conductive resin composition whole quantity, Preferably it is 70-90 mass%, More preferably, it is 75-85 mass%. If the content of the metal hydroxide is less than 70% by mass, it becomes difficult to obtain desired flame retardancy. Moreover, when content of a metal hydroxide exceeds 94 mass%, sufficient moldability will not be acquired, As a result, it will become difficult to obtain the heat conductive sheet which can achieve the objective of this invention.

  (C) The metal hydroxide preferably contains two or more different metal hydroxides having an average particle diameter of 20 μm or more and less than 20 μm. By including different metal hydroxides having an average particle size of 20 μm or more and less than 20 μm, thermal conductivity and flame retardancy tend to be remarkably improved.

  Further, (C) the metal hydroxide preferably has a weight ratio of particles of 20 μm or more and less than 20 μm of 100/1 to 100/80. More preferably, it is 100 / 10-100 / 50, More preferably, it is 100 / 20-100 / 50. Each average particle size (μm) is a volume-based particle size measured using a laser diffraction / scattering particle size distribution measuring apparatus. The average particle size is usually measured by dispersing aluminum hydroxide in water or ethanol. At this time, if it cannot be dispersed, a surfactant may be used, or it may be appropriately dispersed by a homogenizer or ultrasonic waves. The concentration of the aluminum hydroxide powder to be dispersed is usually 1% or less.

  (C) As the metal hydroxide, a filler surface-treated with a fatty acid treatment, a silane coupling agent, a titanate coupling agent, or the like can also be suitably used.

  In the thermally conductive resin composition of the present embodiment, fatty acid, fatty acid salt, antioxidant, crosslinking agent, thermoplastic resin, filler other than metal hydroxide, difficulty other than metal hydroxide, if necessary. A flame retardant etc. can be added. Examples of the antioxidant include aldehydes, amines, phenols and the like. Examples of the crosslinking agent include organic peroxides, epoxies, isocyanates, di (meth) acrylates, and the like. Examples of the thermoplastic resin include polyethylene, polypropylene, (meth) acrylic resin, polystyrene, and the like. Examples of the filler include carbon black, carbon fiber, graphite fine powder, glass fiber, aluminum oxide, boron nitride, silicon carbide, boron carbide, aluminum nitride, zinc oxide, aluminum, copper and the like. Examples of the flame retardant include nitrogen-based flame retardants (such as triazines), PPE (polyphenylene ether), silicone-based flame retardants, aromatic carboxylic acids and metal salts thereof, boron compounds, and zinc compounds.

  The kneading method for obtaining the heat conductive resin composition of the present embodiment is not particularly limited, and a known method can be used. Examples thereof include blade type kneaders (kneaders, etc.), roll type kneaders (roll mills, taper rolls, pressure kneaders, Banbury mixers, internal mixers, lab plast mills, mix labs, extruders, etc.), preferably kneaders. , Roll mill, banbury and extruder.

  The thermally conductive resin composition of the present embodiment can be processed into a sheet having a thickness of 0.1 to 3 mm depending on the application. The processing method is not particularly limited, but it can be processed by extrusion molding, compression molding, calender molding, or the like, but extrusion molding or calender molding capable of continuous molding and winding is preferable. The sheet-like thermally conductive resin composition can be wound up as a roll with a release film or a transfer adhesive film interposed therebetween. There is no restriction | limiting in particular in the magnitude | size of a sheet | seat, It can process according to a use. A more preferable production method includes a method of forming a sheet by kneading each component with an extruder and extruding it onto a T-die, and winding the sheet together with a release film or a transfer type adhesive film with a sheet take-up device. Extrusion conditions at this time vary depending on the composition or the width of the sheet to be molded, but the set temperature of the extruder is 90 to 190 ° C., the screw rotation speed is 5 to 80 rpm, and the L / D (screw length to diameter ratio) is 20 or more is preferable.

  The heat conductive sheet of this Embodiment is formed in the heat conductive layer which consists of a heat conductive resin composition containing the said (A)-(C) component, and the at least single side | surface of the said heat conductive layer (D) acrylic type And an adhesive layer made of an adhesive.

  In the present embodiment, (D) the pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive is a pressure-sensitive adhesive that allows the heat conductive sheet to be in close contact with a cooling component such as a heating element or a heat sink, and is compatible with the heat conductive sheet ( An acrylic resin is used from the viewpoints of paintability and weather resistance.

  As the (D) acrylic pressure-sensitive adhesive, for example, a polymer obtained by subjecting one or more of the following monomers to solution polymerization, bulk emulsion polymerization, suspension polymerization, or the like can be used. As monomers constituting the acrylic pressure-sensitive adhesive, acrylic acid, methacrylic acid, alkyl group substituted or unsubstituted, and C1-C20 acrylic acid alkyl ester, methacrylic acid alkyl ester, specifically Examples include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, and the like. As monomers other than the above monomers, vinyl acetate, acrylonitrile, acrylamide, styrene, vinylidene chloride, itaconic acid, methylolacrylamide, glycidyl methacrylate, maleic anhydride and the like can be used in combination.

  The acrylic resin can be appropriately crosslinked. In this case, the crosslinking can be carried out by blending a crosslinking agent during the polymerization. Examples of the crosslinking agent include polyurethane resins, epoxy resins, isocyanates, melamine resins, urea resins, etherified amino resins. A metal chelate or the like can be added.

  Moreover, it is preferable that the flame retardant is contained in the adhesion layer which consists of (D) acrylic adhesive. The flame retardant contained in the acrylic pressure-sensitive adhesive is preferably a halogen-free flame retardant from the viewpoint of preventing dioxin generation. For example, phosphoric esters such as triphenyl phosphate and trioctyl phosphate, and melamine as a nitrogen-containing compound. And triazine compounds such as melamine cyanurate and melamine phosphate, guanidine compounds such as guanidine compounds such as guanidine sulfamate, guanidine carbonate and guanidine phosphate, and metal hydroxides such as aluminum hydroxide and magnesium hydroxide. In particular, phosphoric acid esters are preferable from the viewpoint of compatibility with the pressure-sensitive adhesive. These flame retardants may be used alone or in combination of two or more.

  The content of the flame retardant is preferably 5 to 40 parts by mass, more preferably 5 to 30 parts by mass, and still more preferably 8 to 20 parts by mass with respect to 100 parts by mass of the total amount of the acrylic pressure-sensitive adhesive. When the content of the flame retardant is less than 5 parts by mass, desired flame retardancy tends to be hardly obtained.

  The sheet for the pressure-sensitive adhesive layer of the present embodiment can be produced by a general method. For example, the above raw material mixture is adjusted to an appropriate viscosity using a solvent or the like, and a release-treated PET film (base It can be obtained by coating with a doctor blade and drying.

  The thickness of the pressure-sensitive adhesive layer is 1 to 10 μm, more preferably 1 to 8 μm, from the viewpoints of required adhesive strength and thermal conductivity. If the thickness of the adhesive layer is less than 1 μm, it may be peeled off when the heat conductive sheet is attached to a heating element such as an electronic device component. Also, if it exceeds 10 μm, the adhesive strength becomes strong and difficult to peel off, but when pasting to a heating element such as an electronic device, if it is necessary to peel it off due to an error in the pasting position, etc., the sheet or heating element may be damaged. Inconvenience may occur, which is not preferable. Further, it is not preferable because it is difficult to remove heat generated from a heating element such as an electronic device component and the effect of flame retardancy is insufficient.

  The heat conductive sheet of the present embodiment has heat conductivity, and the heat conductivity is preferably 1.0 W / m · K or more. The thermal conductivity can be measured by a method based on ASTM (American Society for Testing and Materials) D5470.

  Moreover, it is preferable that the heat conductive sheet of this Embodiment satisfy | fills the V-0 specification of UL94 specification (standard number 94 of Underwriters Laboratories Inc.). The UL94 standard is a standard related to a plastic material flammability test for equipment and appliance parts, and satisfying this standard is classified as a material having high flame retardancy. Since the heat conductive sheet of this Embodiment is used for an electrical product etc., a flame retardance is important. For example, since aluminum hydroxide decomposes at 200 ° C. or higher to release water, flame retardancy can be imparted to a composition containing aluminum hydroxide.

  The heat conduction sheet according to the present embodiment allows the generated heat to escape efficiently by being sandwiched between a heat-generating part of an electronic component or a semiconductor device and a heat-radiating component or a heat-dissipating plate. It is possible to reduce the thermal deterioration of the product, reduce the failure, and extend the life. In addition, it is possible to re-paste, so when mounting the heat conduction sheet to the heat-radiating component or heat-dissipating plate, when the sheet is mistakenly attached, or when the position of application is shifted, damage to the heat-generating component when the sheet is peeled off, This is advantageous because it can reduce problems caused by warpage.

  Specific applications of the heat conductive sheet of the present embodiment include computer CPU (central processing element), liquid crystal backlight, plasma display panel, organic EL panel, LED element, organic EL element, secondary battery or its peripheral Examples include equipment, similarly radiators of electric motors, Peltier elements, inverters, (high) power transistors, and the like.

  In particular, LED-related components such as LED-backlights, organic EL-backlights, and LED lighting generate large amounts of heat, and heat is likely to be non-uniform, and a structural design for heat dissipation and soaking is necessary. For example, a good heat dissipation / soaking effect can be obtained by sticking the heat conductive sheet on the back of the LED substrate and further sticking it on a heat sink (such as an aluminum chassis).

Hereinafter, the present embodiment will be specifically described by way of examples and comparative examples, but the present embodiment is not limited to these examples.
The following were used for each component in Examples and Comparative Examples.
[material]
<(A) Styrenic thermoplastic elastomer>
A hydrogenated copolymer of a conjugated diene and a vinyl aromatic compound was produced by the following polymerization method.
-Reaction conditions, etc. Reactor: Stirrer with internal volume of 10 L and jacketed tank reactor Reaction temperature: 70 ° C was maintained during polymerization. The temperature was maintained at 65 ° C. during the hydrogenation reaction.
Hydrogenation catalyst: 1 liter of dried and purified cyclohexane was charged into a hydrogenation catalyst preparation reaction vessel purged with nitrogen, and 100 mmol of bis (η5-cyclopentadienyl) titanium dichloride was added. An n-hexane solution containing 200 mmol of trimethylaluminum was added with sufficient stirring, and the mixture was reacted at room temperature for about 3 days.
Reaction procedure (i) 10 parts by mass of cyclohexane was charged into a reactor and adjusted to a temperature of 70 ° C.
(Ii) As the first stage reaction, 0.076 parts by mass of n-butyllithium, N, N, N ′, N′-tetramethylethylenediamine (hereinafter abbreviated as TMEDA) is added to 1 mol of n-butyllithium. 0.4 mol was added.
(Iii) A cyclohexane solution (monomer concentration: 22% by mass) containing 8 parts by mass of styrene was added over about 3 minutes, and reacted for 30 minutes after completion of the addition.
(Iv) As the second-stage reaction, a cyclohexane solution (monomer concentration of 22% by mass) containing 48 parts by mass of 1,3-butadiene and 36 parts by mass of styrene is continuously supplied to the reactor at a constant rate over 60 minutes. And allowed to react for 30 minutes after the addition.
(V) As a third stage reaction, a cyclohexane solution containing 8 parts by mass of styrene (monomer concentration 22% by mass) was added over about 3 minutes and reacted for 30 minutes after completion of the addition to obtain a copolymer.
(Vi) The hydrogenation catalyst was added to the obtained copolymer in an amount of 100 mass ppm in terms of titanium, and a hydrogenation reaction was performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C.
(Vii) After completion of the reaction, methanol is added, and then octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate as a stabilizer is 0.3% by mass based on the copolymer. To obtain a hydrogenated copolymer.
The resulting hydrogenated copolymer had a weight average molecular weight of 16.5 × 10 ⁴ , a molecular weight distribution of 1.2, and a hydrogenation rate of 99%. As a result of dynamic viscoelasticity measurement, the peak temperature of tan δ was -15 ° C. As a result of DSC measurement, no crystallization peak was present.
Further, the content of vinyl aromatic compound units determined from the pre-hydrogenation copolymer obtained after the third stage reaction is 52% by mass, the content of the polymer block composed of vinyl aromatic is 16% by mass, 1, The vinyl bond content in the 3-butadiene part was 21% by mass.

<(B) Rubbery softener>
Diana process oil PW-380 manufactured by Idemitsu Kosan Co., Ltd. was used.

<(C) Metal hydroxide (aluminum hydroxide)>
High white aluminum hydroxide manufactured by Nippon Light Metal Co., Ltd. was used.
The average particle size of the metal hydroxide is shown in Table 1.

<(D) Acrylic adhesive>
Acrylic solvent adhesive (Soken Chemicals Co., Ltd. SK1717 solid content 45 mass%) was diluted with toluene, and triarylisopropyl phosphate (Ajinomoto Fine Techno Co., Ltd. Leophos 50) as a flame retardant was solidified with the above acrylic adhesive. 10 mass% was added with respect to min, and the flame retardant containing acrylic solvent adhesive (D-1) was obtained. Then, it apply | coated with the doctor blade on the PET film by which the peeling process was carried out, it was made to dry (140 degreeC x 1 hour), and the sheet | seat for adhesive layers of the thickness shown in Table 1 was obtained.
Moreover, the sheet | seat for adhesive layers which consists of a flame retardant non-containing acrylic solvent adhesive (D-2) by the method similar to the above except not having added the said flame retardant was obtained.

<Fluorine resin and / or modified product of fluororesin (acrylic modified PTFE)>
Mitsubishi Rayon Metablen A-3800

[Sheet manufacturing method]
<Kneading>
Components (A) to (C) and acrylic-modified PTFE were kneaded at 150 ° C. for 5 minutes using a Laboplast mill (manufactured by Toyo Seiki) to obtain a heat conductive resin composition.
<Sheet molding>
The heat conductive resin composition was kneaded at 150 ° C. using a 3 inch roll kneader to form a sheet. Furthermore, a press-formed product sheet (heat conductive layer) 120 mm long × 220 mm wide and 0.3 mm thick was obtained by press molding heated at 170 ° C.
<Lamination molding of adhesive layer and heat conductive layer>
Using the press-formed product sheet (heat conductive layer) obtained by the above-mentioned sheet molding, the thermal adhesive laminator (MCK MRK-400 custom-made, roll width 400 mm) and the adhesive layer sheet and the heat conduction The heat conductive sheet which laminated | stacked the layer was obtained. The roll temperature was 50 ° C. and the roll pressure was 0.5 MPa.

Evaluation was performed according to the following items. The results are shown in Table 1.
[Measuring method]
<Average particle size>
The measurement was performed using a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba, Ltd.). In addition, the dispersion | distribution of the sample in a dispersion medium irradiated the ultrasonic wave for 1 minute.
<Flame retardance>
The measurement was performed according to the UL94 standard. The thickness of the test piece was 0.3 mm.
<Thermal conductivity>
In accordance with ASTM (American Society for Testing and Materials) D5470, thermal conductivity was measured using a resin material thermal resistance measuring device (manufactured by Hitachi, Ltd.). The measurement temperature was 30 ° C., and the thickness of the test piece was 0.3 mm.
<Adhesive strength>
In accordance with JIS Z 0237, a 90 ° peel test was performed, and measurement was performed in an environment of 23 ° C. and 50% RH. The adherend was an aluminum plate (material A5052, thickness 1.6 mm), peeling rate 100 mm / min.
<Evaluation of workability>
The PET film was peeled off using the heat conductive sheet laminated | stacked the adhesion layer obtained above, and it affixed on the aluminum board (material A5052, thickness 1.6mm). After 10 minutes, the heat conductive sheet can be re-applied, and after 1 day the sheet was not damaged and fixed. ○ After 10 minutes, the sheet could not be re-applied and the sheet was damaged. did.

As is clear from the results in Table 1, the heat conductive sheets of the present embodiment (Examples 1 to 4 and Reference Example 1 ) are excellent in heat conductivity and flame retardancy, and also have good workability in sheet pasting. Met. In particular, the heat conductive sheets of Examples 1 to 4 containing a flame retardant in an acrylic pressure-sensitive adhesive had particularly good flame retardancy.
On the other hand, the heat conductive sheets of Comparative Examples 1 and 2 had a large adhesive layer thickness and were inferior in sheet pasting workability.
When the resin composition containing components (A), (B) and (C) is kneaded with a lab plast mill, the heat conductive sheet of Comparative Example 3 cannot be filled with a predetermined amount of component (C). Since then, it could not be evaluated.
The heat conductive sheets of Comparative Examples 4 and 5 were inferior in heat conductivity and flame retardancy.

  The heat conductive sheet in the present invention is a heat conductive sheet having excellent heat conductivity and flame retardancy and excellent workability that can be easily attached to a heating element on an electronic board inside an electronic device. Radiating parts for computers such as projectors, radiating parts for DVD players and DVD recorders, radiating parts for HDD recorders, radiating parts such as display power supply units for home TVs, plasma displays, liquid crystal TVs, mobile phones, various computers Industrial applications for applications that require high thermal conductivity, such as heat dissipation parts used in various AV equipment, OA equipment, car stereos, car navigation systems, inverters, lighting, air conditioner automotive electrical components, etc. Has availability.

Claims (11)

(A) Styrenic thermoplastic elastomer 5 to 25% by mass,
(B) 1-20% by mass of a softener for rubber, and (C) 70-94% by mass of a metal hydroxide,
A heat conductive layer comprising a heat conductive resin composition containing
A heat conductive sheet having (D) an adhesive layer made of an acrylic adhesive formed on at least one side of the heat conductive layer,
(D) The thickness of the pressure-sensitive adhesive layer comprising the acrylic pressure-sensitive adhesive is 1 μm or more and less than 10 μm,
The said (D) component further contains a flame retardant, and the said flame retardant is a 1 type, or 2 or more types of mixture chosen from phosphate ester, The heat conductive sheet. The heat conductive sheet of Claim 1 whose thickness of the adhesion layer which consists of said (D) acrylic adhesive is 1-8 micrometers. The (D) acrylic pressure-sensitive adhesive is selected from the group consisting of acrylic acid, methacrylic acid, an alkyl group substituted or unsubstituted, and an alkyl alkyl ester having 1 to 20 carbon atoms and an alkyl methacrylate ester. The heat conductive sheet of Claim 1 or 2 which is a polymer obtained by carrying out solution polymerization, block emulsion polymerization, or suspension polymerization of the 1 type (s) or 2 or more types of monomer obtained. The heat conductive sheet according to any one of claims 1 to 3 , wherein the component (C) is aluminum hydroxide. The said (A) component is a heat conductive sheet of any one of Claims 1-4 which is a copolymer of a conjugated diene and a vinyl aromatic compound. Wherein component (A) is a copolymer in the hydrogenated copolymer obtained by adding hydrogen and / or the modified hydrogenated copolymer of a conjugated diene and a vinyl aromatic compound, of claim 1-5 The heat conductive sheet of any one of Claims. The heat conductive sheet of Claim 5 or 6 whose content of the vinyl aromatic compound unit of the copolymer of the said conjugated diene and a vinyl aromatic compound is 30 to 90 mass%. The content of the polymer block comprising the vinyl aromatic compound copolymer of a conjugated diene and a vinyl aromatic compound is less than 40 wt%, the heat conductive sheet according to any one of claims 5-7. The heat conductive sheet according to any one of claims 5 to 8 , wherein the copolymer of the conjugated diene and the vinyl aromatic compound has a weight average molecular weight of 5 x 10 ^{4 to} 100 x 10 ⁴ . The hydrogenated copolymer and / or the modified hydrogenated copolymer double bond hydrogenation ratio derived from the conjugated diene is 10% or more, the thermal conductive sheet according to any one of claims 6-9. The heat conductive sheet of any one of Claims 1-10 whose heat conductivity is 1.0 W / m * K or more.