JP2002363429A - Heat-conductive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-conductive composition having excellent thermal conductivity, workability and removability. SOLUTION: This heat-conductive composition is characterized in that the composition comprises a heat-conductive filler and has mastic curability by moisture. A composition composed of (A) a compound selected from a polyisobutylene containing hydrolyzable silyl groups at both molecular chain terminals, a polyether containing hydrolyzable silyl groups at both molecular chain terminals and an acrylic copolymer containing hydrolyzable silyl groups at both molecular chain terminals, (B) a condensation curing catalyst and (C) a heat-conductive filler may be cited as the composition having mastic curability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermally conductive composition capable of efficiently conducting heat to a component that generates heat.

[0002]

2. Description of the Related Art Heat-generating electronic components, such as transistors and thyristors, used in electronic equipment generate heat during use and must be removed. Conventionally, heat is diffused by attaching a radiating fin such as copper or aluminum or a metal plate to these components, and the heat is removed from the components. The radiating fins and metal plates (hereinafter collectively referred to as radiating members) are solid, and even if they are brought into close contact with electronic components such as transistors, fine gaps are created.
Thermal conductivity was improved.

In recent years, with the miniaturization, high integration, and high output of electric / electronic devices, the amount of heat generated per unit area of mounted components has become extremely large, and the heat may damage the components themselves or cause malfunctions. there's a possibility that. Further, since heat is also transmitted to electronic components in the vicinity of the electronic components, malfunctions and the like may be caused such as adverse effects on operation and performance. Therefore, heat dissipation is required to be improved more than before, and heat conduction sheets, heat radiation adhesives, heat radiation silicone grease, etc., which have high adhesion for the purpose of improving the heat conductivity between the heat-generating component and the heat radiation member, are required. Highly efficient ones have been devised.

[0004] For example, an ultra-highly integrated computing chip such as a CPU is used inside a personal computer, and the amount of heat generated from these chips is extremely large. When heat-dissipating silicone grease is used for such heat-generating components, the amount of heat generated is large,
The grease component evaporates or the grease oil and the conductive filler component are separated. Evaporated components can adversely affect electronic components, especially contacts,
Not preferred. Further, when the components are separated, not only is the heat conduction performance lowered, but also the grease oil drips and flows, contaminating the surroundings, which is not preferable.

[0005] When a heat-radiating adhesive is used, since it is curable, there are no problems such as evaporation or outflow of components. However, when the adhesive is used for repair, inspection or replacement of parts. Removal is difficult and requires labor and skill.

The use of a molded heat-radiating sheet eliminates the drawbacks such as outflow of components and removability, but lacks adhesion between the two because it pushes against solids. In addition, since the sheet is sheet-shaped, the thickness is large, and the sheet lacks fundamental performance that thermal conductivity is not good.

Therefore, Japanese Patent Application Laid-Open Nos. 63-119554 and 1-228848 disclose an uncured heat conductive compound layer between a heat-generating component and a heat radiating member, and a heat-generating component located around the uncured compound. A package heat dissipation structure provided with a rubber layer for bonding members has been proposed. According to this method, the bonded portion is only the peripheral portion, so it is excellent in detachability, and most of the space between the heat generating component and the heat radiating member is an uncured compound, so that the thermal conductivity is good, Since the surrounding rubber layer covers the uncured portion, there is an advantage that the uncured compound does not flow out.

[0008]

However, the method disclosed in the above publication does not describe a specific method for forming an uncured compound portion and a rubber layer. Usually this is first formed by
Apply the uncured compound to the center of the heat dissipating member and adhere molding rubber around it with an adhesive to press it against the heat-generating component, or apply the uncured compound and then cure around to form a rubber. A method of applying a curable material and compressing it.

In the former method, since the rubber layer is a molded product, it is not easy to position the rubber layer around the heat radiating member.
In some cases, the position may be shifted when pressure-bonded to the heat-generating member, resulting in poor workability. Automatic line travel by robots is an extremely difficult task.

The latter method involves only the step of applying two kinds of liquid materials to the corresponding places, so that the operation is not so difficult and can be automated. For example, the amount of application of the uncured compound at the center is reduced. If the amount is too large, the surrounding curable rubber component may be washed away when the heat radiating member and the heat-generating component are pressed, and the desired performance may not be obtained. It is not easy to completely cover the rubber layer with this balance because it is necessary to keep the application amount and the pressing force constant.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made by intensive studies in order to solve the drawbacks of these conventional heat conductive compositions. That is, the present invention contains a heat conductive filler, A thermally conductive composition having mastic curability.

Hereinafter, the present invention will be described in detail.

The heat conductive composition of the present invention has mastic curability. The mastic curability of the present invention is maintained in a liquid state in a storage container, and is removed from the storage container and exposed to the atmosphere, whereby the surface of the composition is cured to have a rubbery,
Although the composition becomes a plastic, the inside of the composition does not cure and remains in a liquid or gel state. The degree of this is that the cured film thickness per month in an atmosphere at a temperature of 20 ° C. and a relative humidity of 60% is 0.5 to 3 mm. After one month, the curing does not proceed and the inside remains uncured.

The heat conductive composition of the present invention uses a mastic curable resin. For example, (A) a polyisobutylene having a hydrolyzable silyl group at both molecular chain terminals, and (B) a condensation curing catalyst , (C) a composition comprising a thermally conductive filler, (A) a polyether having hydrolyzable silyl groups at both molecular chain terminals, (B) a condensation curing catalyst, and (C) a composition comprising a thermally conductive filler. (A) an acrylic copolymer having a hydrolyzable silyl group at both ends of a molecular chain, (B)
And a composition comprising a condensation curing catalyst and (C) a thermally conductive filler. The details will be described below.

It is necessary that both ends of the molecular chain of the component (A) are blocked with a hydrolyzable silyl group. That is, due to the presence of the hydrolyzable group, such a polymer is hydrolyzed and polycondensed in the presence of moisture to form a rubber elastic body or a plastic-like cured product. The hydrolyzable silyl group is obtained by bonding at least one hydrolyzable group to a silicon atom. Examples of the hydrolyzable group include a carboxyl group, a ketoxime group, an alkoxy group,
Examples include an alkenoxy group, an amino group, an aminoxy group, an amide group and the like. The number of these hydrolyzable groups bonded to the silicon atom is not limited to one, and two or three hydrolyzable groups may be bonded to the same silicon atom. Further, naturally, other organic groups may be bonded to the silicon atom to which these hydrolyzable groups are bonded,
Examples of such an organic group include an alkyl group such as a methyl group, an ethyl group and a propyl group; a cycloalkyl group such as a cyclohexyl group; an alkenyl group such as a vinyl group and an allyl group; an aryl group such as a phenyl group and a tolyl group; A group in which a hydrogen atom of the group is partially substituted with a halogen atom or the like, for example, a chloromethyl group, a 3,3,3-trifluoropropyl group, and the like can be given.

It is preferable to use a base polymer as component (A) that prevents moisture permeation when cross-linking polymerization occurs due to moisture. That is, when crosslinking starts from the surface due to moisture and a cured film is formed, the permeability of the moisture becomes extremely low due to the cured film itself, and the cured film is no longer cured. Generally, an organic composition which has been cross-linked and cured tends not to pass moisture, but siloxane and the like gradually pass moisture. In other words, moisture gradually permeates into the interior over a long period of time and hardens to the interior.

Examples of such a base polymer include polyisobutylene having a hydrolyzable silyl group at both terminals. The polyisobutylene, which is the main chain of the base polymer, contains at least 50 mol%, preferably
0 mole percent of the repeating units _{- (CH 2 -C (CH 3} ) 2) -
Any linear or branched polymer or a copolymer thereof, which is an isobutylene unit represented by One or several hydrocarbon monomers, such as isomers of styrene or butylene and derivatives of styrene, isoprene and butadiene are copolymerized with isobutylene. Particularly preferred comonomers are selected from 1-butene, α-methylstyrene or isoprene. Most preferably, the polymer is a homopolymer consisting essentially of isobutylene units.

For the purpose of achieving low moisture permeability, the polyisobutylene main chain preferably has a number average molecular weight of 1,000 to 20,000. When the number average molecular weight is out of this range, it may be difficult to form a cured rubber having satisfactory properties, or the workability may be reduced.

To control the number average molecular weight, a bifunctional moiety such as 1,4-bis (α-chloroisopropyl) benzene or 1,3,5-tris (α-chloroisopropyl), proposed by Kennedy. ) A trifunctional component such as benzene as initiator and chain transfer agent, BCL3
It is produced by an inifer method (US Pat. No. 4,276,394) in which isobutylene is cationically polymerized using as a catalyst.

The monomer which can be copolymerized with isobutylene as a repeating unit other than isobutylene is one having 4 to 12 carbon atoms.
Olefins, vinyl ethers, aromatic vinyl compounds,
Examples include vinyl silanes and allyl silanes. Specific examples of the copolymer component of such a monomer include 1-butene, 2-butene, 2-methyl-1-butene, 3-methyl-2-butene, pentene, hexene, cyclohexene,
Aliphatic olefins such as vinylhexane, 5-ethylidene norbornene, indene and β-pinene; dienes such as cyclopentadiene and dicyclopentadiene; and styrenes such as styrene, α-methylstyrene and p-chlorostyrene. Can be.

The introduction of the hydrolyzable silyl group into the polyisobutylene may be carried out by a known method, for example, a saturated hydrocarbon polymer having a functional group such as a hydroxyl group or an acid anhydride group at the terminal or main chain. To an organic compound having an active group and an unsaturated group having reactivity with the functional group,
Next, a hydrosilane having a hydrolyzable group is allowed to act on the obtained reaction product to perform hydrosilylation. Further, the polyisobutylene having a hydrolyzable silyl group,
A terminal functional type, preferably all terminal functional type polyisobutylene obtained by a polymerization method called an inifer method can be produced. Such a production method is described in, for example, JP-A-63-6041, JP-A-63-0003, and JP-A-9-286895.

The component (A) having a main chain of polyisobutylene is sold, for example, as "Epion" series of Kaneka Chemical Industry Co., Ltd.

Next, the base which can be the component (A) of the present invention
Examples of the polymer include a polyoxyalkylene polymer.
It is. Polyoxyalkylene polymers make up the main chain
An oxyalkylene unit is -CH₂CH₂O-, -CH
₂CH (CH₃) O-, -CH₂C (CH₃CH₃) O
-, -CH₂CH₂CH₂CH₂O- etc.
However, in terms of availability and price,
Is -CH₂CH (CH ₃) The main chain is composed of O- units.
Are preferred. Of course, the oxy
Alkylene units are not only one type but also two or more types
May be mixed. In addition, such oxyalkylene
The aforementioned hydrolyzable silicones are attached to both ends of the main chain consisting of
The introduction of an oxy group having an allyl group at the terminal
Hydroxylene with hydrolyzable silyl group
Addition reaction with silane in the presence of platinum catalyst, or
Or oxyalkylene polymer having an allyl group at the end
And halogenated alkylsilyl having hydrolyzable silyl group
In the presence of metallic sodium or metallic potassium
And a condensation reaction.

The component (A) whose main chain is a polyoxyalkylene polymer is sold, for example, as the “Syril” series of Kaneka Chemical Industry Co., Ltd., and the “Exester” series of Toshiba Silicone Co., Ltd.

Further, as the base polymer which can be the component (A) of the present invention, those having a main chain of a copolymer of an alkyl (meth) acrylate are also exemplified. Such polymers are represented by _CH ^{2 =} CR 1 -COOR 2.
For example, methyl (meth) acrylate, propyl (meth) acrylate, ethylhexyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate,
(Meth) acrylic acid esters such as tridecyl (meth) acrylate, stearyl (meth) acrylate and cetyl (meth) acrylate are used alone or in a radical copolymerized form of two or more kinds.

In the present invention, among the acrylic copolymers, the above-mentioned R ^{2 of the} (meth) acrylic acid ester has 1 to 8 carbon atoms.
Such as those alkyl groups, (meth) acrylate, (meth) acrylate, propyl (meth) ethylhexyl acrylate, butyl (meth) acrylate, and monomer units such as the R ² carbon atoms Those having 10 to 30 alkyl groups, for example, tridecyl (meth) acrylate,
It is desirable that the copolymer be a copolymer of monomer units such as (meth) acrylates such as stearyl (meth) acrylate and cetyl (meth) acrylate. R ² has 1 carbon atom
And a monomer which is an alkyl group having 8 to 8 carbon atoms and R ² has 10 carbon atoms.
The content ratio of the monomer which is an alkyl group of 30 to 30 is 9 by weight.
5: 5 to 40:60 is preferred.

The copolymer of the alkyl (meth) acrylate may be any copolymer as long as the total of the (meth) acrylate monomers contained in the copolymer exceeds 50% by weight. However, in consideration of low moisture permeability, it is preferable that the total of the acrylate monomers exceeds 70% by weight. Monomer units other than the (meth) acrylic acid ester monomer copolymerizable with the base polymer include acrylic acid such as acrylic acid and methacrylic acid; acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylic acid An amide group such as an amide,
Epoxy groups such as chrysidyl acrylate and glycidyl methacrylate, diethylaminoethyl acrylate,
Monomers containing an amino group such as diethylaminoethyl methacrylate and aminoethyl vinyl ether; other acrylonitrile, iminol methacrylate, styrene,
and monomer units such as α-methylstyrene, alkyl vinyl ether, vinyl chloride, vinyl acetate, and vinyl propionate. The base polymer is a copolymer (A)
The number average molecular weight is preferably from 500 to 100,000 from the viewpoint of easy handling.

There are various methods for introducing a hydrolyzable functional group-containing silicon into a copolymer of the alkyl (meth) acrylate of the base polymer. For example, there are various methods for introducing a polymerizable unsaturated bond and a reactive silicone. Compounds having a functional group (for example, CH ₂ ＣＨCHRSi (OC
H ₃ ) ₃ ) and a monomer having units represented by the general formulas (I) and (II) and copolymerizing the compound, a compound having a polymerizable unsaturated bond and a reactive functional group (for example, Acrylic acid) is added to a monomer of the general formula (meth) acrylate to copolymerize, and then the resulting copolymer is a compound having a functional group capable of reacting with a hydrolyzable functional group and a reactive functional group (Eg, a compound having an isocyanate group and a —Si (OCH ₃ ) ₃ group). Details of the production method are described in
No. 1122642.

The component (A) whose main chain is a copolymer of an alkyl (meth) acrylate is sold, for example, as “MS polymer” or “MA polymer” by Kaneka Corporation.

The component (B) used in the present invention is a moisture curing catalyst. Known moisture curing catalysts can be used. For example, lead-2-ethyl octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin bisacetylacetonate, dibutyltin dimethoxide, dibutyltin bis (trimethoxysilyl), butyltin tri-2-ethylhexoate, Iron-2
-Ethylhexoate, cobalt-2-ethylhexoate, manganese-2-ethylhexoate, zinc-2-
Metal lead of organic acid carboxylic acid such as ethylhexoate, stannous caprylate, tin naphthenate, tin oleate, tin butylate, tin naphthenate, zinc naphthenate, cobalt naphthenate, stearic acid, and tetrabutyl titanate , Tetra-2-ethylhexyl titanate, triethanolamine titanate, tetra (isopropenyloxy) titanate, diisopropoxybis (ethyl acetoacetate)
Titanium, organic titanates such as diisopropoxybis (acetylacetone) titanium, organic titanium compounds such as organosiloxy titanium, β-carbonyl titanium,
Alkoxyaluminum compounds, quaternary ammonium salts such as benzyltriethylammonium acetate, potassium acetate, sodium acetate, alkali metal lower fatty acids such as lithium oxalate, dimethylhydroxyamine,
And dialkylhydroxylamine such as diethylhydroxyamine.

The addition amount of the component (B) is appropriately determined depending on the component (A) used, but is 0.1 to 10 parts by weight based on 100 parts by weight of the component (A). In other ranges, the storage stability is lacking, and the mastic curability is reduced, and there is a possibility that the mastic hardens to the inside.

As the heat conductive filler used for the component (C) used in the present invention, known fillers can be used. For example, aluminum hydroxide, magnesium hydroxide,
Calcium carbonate, magnesium carbonate, calcium silicate,
Inorganic oxides such as magnesium silicate, calcium oxide, magnesium oxide, alumina powder, silica, etc., nitrogen inorganic compounds such as aluminum nitride, boron nitride and silicon nitride, organic substances such as carbon, graphite, silicon carbide, silver, copper, aluminum etc. Metal powder is preferably used. These are 1
It is possible to use a combination of two or more species.

The heat conductive filler is spherical, powdery, fibrous,
Any shape such as a needle shape and a scale shape may be used, and the average particle size is about 1 to 100 μm.

The amount of the heat conductive filler varies depending on the shape and type of the filler used.
About 80% by volume, more preferably 20 to 50% by volume.
%. If it is less than 10%, the heat conduction performance is not sufficient, and if it is more than 80%, the adhesive strength when the resin composition is cured becomes weak, and the adhesiveness between the heat radiating member and the heat generating component becomes weak.

The heat conductive composition of the present invention comprises the above-mentioned essential components. If necessary, an inorganic filler in the form of a fine powder may be added in order to improve the flow characteristics before curing. For example, fumed silica, quartz fine powder, calcium carbonate, fumed titanium dioxide, diatomaceous earth, aluminum hydroxide, particulate alumina, magnesia, zinc oxide, zinc carbonate, and silanes, silazanes, and low-polymerization degree siloxane , Organic compounds and the like which have been surface-treated.

Further, a storage stabilizer, an organic solvent, a fungicide, a flame retardant, a plasticizer, a thixotropy-imparting agent, an adhesion-imparting agent, a curing accelerator, a pigment, and the like are added to the heat conductive composition of the present invention. be able to. For example, storage stabilizers such as methyltrimethoxysilane and phenyltributoxysilane; plasticizers such as hydrocarbon compounds such as polybutene, hydrogenated polybutene, liquid polybutadiene, hydrogenated polybutadiene, paraffin oil, and naphthenic oil; and chlorine. Paraffins, phthalic acid esters such as dibutyl phthalate and di (2-ethylhexyl) phthalate, non-aromatic dibasic acid esters such as dioctyl adipate and dioctyl sebacate, esters of polyalkylene glycol, tricresyl phosphate and the like And the like.

The heat conductive composition of the present invention can be cured by moisture in the air. Further, the interior that does not come into contact with air becomes uncured or gelled. In the present invention, this curing mode is referred to as mastic curing.
It is 3 mm. Of course, the interior will not harden even after more time.

The heat conductive composition of the present invention can be used for a CPU or an MPU.
It is applied to an arithmetic circuit such as an electronic circuit such as a transistor and a thyristor, and is used between a heat radiation member such as a heat radiation fin and a Peltier element. The method of use will be described with reference to FIG. FIG. 1 shows a case in which it is used between a CPU and a radiation fin. Reference numeral 4 denotes a CPU mounted on the substrate 6, and reference numeral 5 denotes a radiation fin. The heat conductive composition 1 is uniformly applied to the side of the heat radiation fin 5 that comes into contact with the CPU, and is immediately attached to the CPU 4. The heat conductive composition 1 is cured using a metal fitting for fixing the radiation fins 5 or a jig for temporary fixing (not shown). The end 2 of the thermally conductive composition 1 is cured by moisture in the air. However, since the present composition is mastic curable, the inside 3 does not solidify from the end 2 and maintains a liquid or soft gel state. Further, the end portion 2 is solidified to be in a rubber state, and has a function of fixing the radiation fin by bonding to the radiation fin 5 and the CPU 4. Further, the liquid material in the inside 3 does not leak.
Even if a part of the end portion 2 is broken by an impact or the like, moisture in the air permeates from the broken portion from the broken portion to harden the thermoconductive composition 1 slightly inside the broken portion. The end is in a hardened state.

Further, the CPU is used for maintenance and repair.
When it becomes necessary to remove the radiation fins 5 from 4,
The CPU 4 and the radiation fins 5 can be removed by cutting the entire periphery of the end 2 with a knife or a cutter. Since the internal uncured portion 3 is not adhered, it can be removed by wiping with an organic solvent or a surfactant.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 70 g of polyisobutylene having a number average molecular weight of 20,000 and 1 g of dibutyltin laurate, both ends of which are blocked with dimethoxysilyl groups, 3 g of methyltrimethoxysilane as a stabilizer, and 30 g of process oil Then, 800 g of aluminum oxide was mixed as a conductive filler to prepare a heat conductive composition.

Example 2 70 g of a polyoxyalkylene having a number average molecular weight of 17000, 1 g of dibutyltin laurate, 3 g of methyltrimethoxysilane as a stabilizer, 30 g of process oil, 30 g of conductive oil A heat conductive composition was prepared by mixing 800 g of aluminum oxide as a filler.

Example 3 70 g of polyisobutylene having a number average molecular weight of 9700, 1 g of dibutyltin laurate, 3 g of methyltrimethoxysilane as a stabilizer, 30 g of process oil, 30 g of a conductive filler, in which both ends of the molecular chain were blocked with dimethoxysilyl groups And a heat conductive composition was prepared by mixing 800 g of aluminum oxide.

COMPARATIVE EXAMPLE 1 70 g of a polyorganosiloxane having a number average molecular weight of 15,000 and both ends of a molecular chain blocked with a dimethoxysilyl group,
A thermally conductive composition was prepared by mixing 1 g of dibutyltin laurate, 3 g of methyltrimethoxysilane as a stabilizer, 30 g of process oil, and 800 g of aluminum oxide as a conductive filler.

A thermal conductivity test was conducted using the composition obtained above. 3 g of each composition was applied to the center of a 5 × 5 cm flat heater, and an aluminum heat sink (radiation fin) was pressed against the flat heater. The heat conductive composition was cured by fixing it with a temporary fixing jig for 24 hours. Fan (DCPi manufactured by Alpha Co., Ltd.)
coAce25) was attached. Electric power of 60 W is applied to the flat heater to cause the heater to generate heat, and the surface temperature of the heater and the temperature of the heat sink are measured to determine the thermal resistance of the entire apparatus in ° C / C.
W was calculated. As a result, the composition of Example 1 was 0.01%
° C / W, composition of Example 2 was 0.01 ° C / W, Example 3
Is 0.01 ° C./W, and the composition of Comparative Example 1 is 0.1 ° C./W.
03 ° C./W. When a heat-dissipating silicone sheet was used instead of each composition, the actual value was 0.17 ° C./W.

Further, 3 g of each composition was applied to the center of a 5 × 5 cm aluminum plate, and the aluminum plates were pressed together.
This was left for 3 months in an atmosphere of 25 ° C. and 40% RH.
After the standing, these were separated, and the compositions of Examples 1, 2, and 3 were pryed open from the ends with a flathead screwdriver, and the ends were opened due to cohesive failure. Although the inside was thickened, the composition was uncured and could be removed by wiping with a solvent. Comparative Example 1 could not be opened with a flathead screwdriver. When the cured product was cut open by prying a knife into the joint surface, the center portion was slightly cured although there was a slight uncured portion. It could not be removed by wiping with a solvent or the like.

[0046]

As described above, the thermally conductive composition of the present invention is mastic cured, so that separation and elution of uncured components are suppressed, and since it is not a solid, it has excellent thermal conductivity. Further, repair, replacement, and the like can be easily performed.

[0047]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example to which a heat conductive composition of the present invention is applied.

[Explanation of symbols]

1: heat conductive composition, 2: cured part at end, 3: uncured part inside, 4: heat-generating component, 5: heat dissipation member

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 71/00 C08L 71/00 Y F term (reference) 4J002 BB201 BB231 BG071 BQ001 CH051 CP171 CP181 DA027 DA037 DE077 DE087 DE147 DE237 DF017 DJ007 DJ017 DK007 EG046 EG066 EG086 EN136 EZ006 EZ016 FD017 FD146

Claims (5)

[Claims] 1. A thermally conductive composition containing a thermally conductive filler and having mastic curability by moisture. 2. A film having a mastic curability of 0.5 to 3 m per month in an atmosphere at a temperature of 20 ° C. and a relative humidity of 60%.
The heat conductive composition according to claim 1, which has a curing degree of m. 3. The heat conductive composition according to claim 1, wherein the heat conductive composition comprises (A) polyisobutylene having hydrolyzable silyl groups at both molecular chain terminals, (B) a condensation curing catalyst, and (C) a heat conductive filler. Thermally conductive composition. 4. The heat-conductive composition according to claim 1, wherein the heat-conductive composition comprises (A) a polyether having hydrolyzable silyl groups at both molecular chain terminals, (B) a condensation-curing catalyst, and (C) a heat-conductive filler. Thermally conductive composition. 5. The heat conductive composition according to claim 1, wherein the heat conductive composition comprises (A) an acrylic copolymer having hydrolyzable silyl groups at both molecular chain terminals, (B) a condensation curing catalyst, and (C) a heat conductive filler. A thermally conductive composition as described.