KR20100117264A - Thermally conductive adhesive composition containing carbon fiber and adhesive sheet fabricated using thereof - Google Patents

Abstract

PURPOSE: A thermo-conductive adhesive composition and an adhesive sheet using thereof are provided to secure the uniform adhesive property and the high thermal conductivity by using a particle type filler with a carbon fiber. CONSTITUTION: A thermo-conductive adhesive composition contains an acryl group adhesive resin(100), and a hybrid filler including a carbon fiber(130) and granular fillers(120,125) mixed with a ratio of 1:4~4:1. 20~95 parts of acryl group adhesive resin by volume is mixed with 100 parts of adhesive composition by volume. The acryl group adhesive resin is formed by mixing 0~40 parts of polar monomer by weight with 100 parts of (meth)acrylic acid ester-based monomer with 1~12 carbons by weight.

Description

Thermally conductive adhesive composition containing carbon fiber and adhesive sheet prepared using the same {THERMALLY CONDUCTIVE ADHESIVE COMPOSITION CONTAINING CARBON FIBER AND ADHESIVE SHEET FABRICATED USING THEREOF}

The present invention relates to a thermally conductive pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet prepared by using the carbon fiber, and to a technology for improving the thermal conductivity of the pressure-sensitive adhesive composition while having excellent adhesive properties.

With the recent development of the electrical and electronics industry, the demand for technological and high functionalization of electronic devices and components has been accelerated. In particular, in the display business, it is inevitable to use high power consumption for high brightness, and as electronic components are highly integrated and miniaturized, a lot of heat is generated, causing a problem of deteriorating overall device performance or reliability. Therefore, as part of solving the above problems, it is required to use a high heat-resistant adhesive and a pressure-sensitive adhesive sheet that does not occupy much space while having an effective heat dissipation effect.

In addition to thermal conductivity, the highly heat-resistant adhesive sheet may be generated by electrical insulation and high temperature to prevent problems caused by the flow of electricity. Flame retardancy is required to eliminate the risk of fire. Here, if the thermal inconsistency resulting from thermal expansion due to heat is not alleviated, distortion of the upper and lower deposits may be caused.

In addition, the thermally conductive adhesive is located in the form of a film between the heat sink and the heat generating element to facilitate heat dissipation to the outside to facilitate heat transfer to the heat sink. In this case, the polymer used as the substrate has a thermal conductivity of 0.1 to 0.5 W / mK, and the particles having high thermal conductivity are mixed therewith to obtain a desired thermal conductivity.

Silicone resin is mainly used as a base material in such a conventional thermally conductive adhesive. However, silicone resins are expensive and have a slow curing rate, which causes a long processing time. In addition, when the sheet itself is used for the adherend having irregularities, there is a disadvantage that does not give a sufficient adhesive strength.

In addition, in the case of using the particulate filler having a thermal conductivity, it is inevitable to use a large amount of filler in order to exhibit a high thermal conductivity, which causes a problem that the adhesive force is lowered.

1 is a schematic view showing a pressure-sensitive adhesive composition according to the prior art.

Referring to FIG. 1, it can be seen that the content of the particulate filler 20 dispersed in the silicone-based resin 10 is insufficient so that the thermal conductive network 30 is not normally formed. In addition, since the specific gravity of the particulate filler 20 is heavy when the adhesive sheet is manufactured, a problem arises in which the particulate fillers 20 are driven to one side, so that the adhesive force of the portion in which the particulate fillers 20 are concentrated is reduced.

In order to solve this problem, a pressure-sensitive adhesive using an acrylic pressure-sensitive adhesive is used instead of a silicone base material, but an acrylic pressure-sensitive adhesive using a thermosetting method also takes a long processing time, and also has a basic and acidic particulate filler. The viscosity increased rapidly due to the acid base reaction between the acrylic adhesive resin and a problem in workability.

In addition, since the filler to be used has a high specific gravity, there is a problem that the filler is settled for a long processing time, it is difficult to form a thermal conductive network, and the adhesive sheet has a problem in that both sides have different adhesive strength.

According to the present invention, carbon fibers having high thermal conductivity are mixed with particulate fillers to provide uniform adhesive properties and high heat dissipation performance even with a small volume, and reduce the specific gravity of the thermally conductive adhesive sheet to reduce the weight of the applied product. It is an object of the present invention to provide a thermally conductive adhesive composition containing carbon fibers that can be implemented.

In addition, while using the pressure-sensitive adhesive composition to prepare a pressure-sensitive adhesive sheet, a silane coupling agent surface-treated using a particulate filler, to provide a pressure-sensitive adhesive sheet further improved workability and thermal conductivity.

The thermally conductive adhesive composition according to the present invention comprises a hybrid filler based on an acrylic adhesive resin and having a carbon fiber to particulate filler mixed in a volume ratio of 1: 4 to 4: 1.

Here, the content of the acrylic pressure-sensitive adhesive resin based on 100 parts by volume of the thermally conductive pressure-sensitive adhesive composition is 20 to 95 parts by volume is added, the hybrid filler is characterized in that 5 to 80 parts by volume is added, the acrylic pressure-sensitive adhesive resin is carbon number 0-40 weight part of polar monomers copolymerizable with the said monomer are mixed with respect to 100 weight part of (meth) acrylic acid ester monomers which have an alkyl group of 1-12, The said (meth) acrylic acid ester monomer is ethyl (Meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and isononyl It is characterized in that at least one selected from the group consisting of (meth) acrylate, wherein the acrylic pressure-sensitive adhesive is UV light The carbon fiber is characterized in that the thermal conductivity of 50 W / mK or more, the carbon fiber is characterized in that the pitch-based (Pitch) carbon fiber, the apparent appearance of the carbon fiber and the particulate filler The density is 3.0 g / cm 3 or less, the particulate filler is aluminum oxide (Alumina or Al ₂ O ₃ ), magnesium oxide (MgO), zinc oxide (ZnO), boron nitride (BN), aluminum nitride (AlN ), Silicon carbon (SiC), aluminum hydroxide (Al (OH) ₃ ), magnesium hydroxide (Mg (OH) ₂ ), graphite, carbon nanotube (CNT) and graphene (graphene) It characterized in that it comprises at least one selected, characterized in that the particulate filler is surface-treated with 0.01 to 5.0 parts by weight of a silane coupling agent per 100 parts by volume of the thermally conductive adhesive composition, the silane coupling agent is carbon- With carbon double bonds And an optical initiator added at 0.01 to 10 parts by weight based on 100 parts by weight of the acrylic adhesive resin, wherein the photoinitiator is a benzene, a benzene isomer compound, a benzyl ketal compound, or an α-hydroxyalkylphenone compound. , α, α-dialkoxyacetophenone derivative compound, characterized in that at least one of the curing agent, characterized in that it comprises a curing agent added in 0.05 to 30 parts by weight based on 100 parts by weight of the acrylic adhesive resin, wherein the curing agent is multifunctional And at least one selected from acrylate, 1,6-hexane diol diacrylate, trimethylolpropane triacrylate, glyceryl propoxylated triacrylate, allyl acrylate and allyl ether.

In addition, the thermally conductive adhesive sheet according to the present invention is made of the above-described composition, characterized in that the density is 5.0 g / cm 3 or less, the thickness of the adhesive sheet is characterized in that the thickness of 50 ㎛ to 2 mm.

In addition, the method of manufacturing a thermally conductive adhesive sheet according to the present invention comprises the steps of preparing a first liquid acrylic syrup by photopolymerizing an acrylate and a polar monomer acrylic acid in a glass reactor, mixing a photoinitiator and a crosslinking agent with the liquid acrylic syrup and then stirring Preparing a second liquid acrylic syrup and adding a hybrid filler in which a pitch-based carbon fiber-to-particulate filler is mixed in a volume ratio of 1: 4 to 4: 1 to the second acrylic syrup, followed by stirring Preparing a pressure-sensitive adhesive composition, degassing the pressure-sensitive adhesive composition using a vacuum pump, and then preparing the pressure-sensitive adhesive composition layer on a silicone-coated PET film, and curing the pressure-sensitive adhesive composition layer by using a UV lamp. It comprises the step of.

The present invention is to prepare a thermally conductive adhesive sheet by mixing a hybrid filler in which carbon fibers and particulate filler is mixed with the acrylic adhesive resin, thereby improving the thermal conductivity of the filler uniformly dispersed without sedimentation, and to maintain excellent adhesive properties It provides the effect of making the adhesive resin.

In addition, the present invention by treating the surface of the filler with a silane coupling agent having a carbon-carbon-carbon double bond to maximize the dispersion effect of the filler, thereby providing an effect that can also maximize the thermal conductivity and adhesive properties.

In this invention, the ultraviolet curable adhesive resin which can be hardened in a short time is used. To this end, it is to use a physical curing method that uses a multifunctional acrylate to form a semi-interpenetrating polymer network structure. In this case, the general polymer has a low thermal conductivity of 0.5 W / mK or less, but the acrylic adhesive resin, which is an amorphous polymer, has a lower thermal conductivity of 0.2 W / mK or less. In addition, photopolymerization shows a difference in physical properties depending on the amount of UV light, the type and amount of the photoinitiator, and the temperature, and the degree of curing is controlled by controlling the reaction rate due to the amount of UV light and the photoinitiator. Therefore, in the present invention, using an acrylic adhesive resin using the ultraviolet curing method, by mixing the particulate filler having a high thermal conductivity and carbon fiber to obtain the desired physical properties.

Hereinafter, based on the above-described technology of the present invention, a thermally conductive adhesive composition having high thermal conductivity and at the same time excellent adhesive properties and a pressure-sensitive adhesive sheet prepared using the same will be described in detail.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and those skilled in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims.

2 is a schematic view showing an adhesive composition according to the present invention.

Referring to FIG. 2, a hybrid filler in which carbon fibers 130 and particulate fillers 120 and 125 are mixed in the acrylic adhesive resin 100 according to the present invention is uniformly dispersed to form a plurality of thermal conductive networks 140. You can see that. It can be seen that this is a very improved result when compared with the thermally conductive network 30 of FIG. 1. Here, the particulate fillers 120 and 125 are represented by the first particulate filler 120 and the second particulate filler 125 to indicate that those having different particle sizes can be used simultaneously. In addition, the drawing schematically shows an embodiment in which the carbon fiber 130 and the particulate fillers 120 and 125 are mixed to form the thermal conductive network 140, the present invention is not limited thereto.

Next, the pressure-sensitive adhesive composition according to the present invention will be described in detail as follows. The content of the acrylic pressure-sensitive adhesive resin based on 100 parts by volume of the pressure-sensitive adhesive composition according to the present invention is preferably added to 20 to 95 parts by volume, the hybrid filler is preferably added to 5 to 80 parts by volume.

In addition, the carbon fiber uses a pitch carbon fiber, it is preferable to use a thermal conductivity of 50 W / mK or more. The apparent density of the carbon fibers and the particulate filler is preferably 3.0 g / cm 3 or less. When the thermal conductivity is less than 50 W / mK, the thermal conductivity decreases, and when the apparent density exceeds 3.0 g / cm 3, the dispersibility is inferior and uniform dispersion is not achieved.

Regarding the thermally conductive adhesive composition of the present invention described above, first, the acrylic adhesive resin that can be used in the present invention is not particularly limited and may be used as long as it can be used as an adhesive in the art.

Examples of preferred acrylic adhesive resins in the present invention include polymers in which a (meth) acrylic acid ester monomer having an alkyl group having 1 to 12 carbon atoms and a polar monomer copolymerizable with this monomer are copolymerized, and partially polymerized by ultraviolet rays. Preference is given to using materials. At this time, the polar monomer is preferably contained by 0 to 40 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester monomer. In addition, the (meth) acrylic acid ester monomers are ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2- Preference is given to using at least one selected from the group consisting of ethylhexyl (meth) acrylate and isononyl (meth) acrylate.

Next, the present invention is stirred and mixed to uniformly disperse the hybrid filler in which the carbon fiber and the particulate filler are mixed in the acrylic pressure-sensitive adhesive resin.

The mixture can then be polymerized, preferably by photopolymerization and curing with ultraviolet radiation to produce a thermally conductive adhesive sheet according to the present invention.

Here, it is preferable to use 0.01-10 weight part of photoinitiators with respect to 100 weight part of acrylic adhesive resins. When less than 0.01 part by weight of the photoinitiator is used, the degree of polymerization of the pressure-sensitive adhesive composition is significantly lowered. If it exceeds 10 parts by weight, the degree of polymerization may be excessively increased and the viscosity may be reduced. Examples of the photoinitiator of the present invention as described above include, but are not limited to, benzene and benzene isomer compounds, benzyl ketal compounds, α-hydroxyalkylphenone compounds, α, α-dialkoxyacetophenone derivative compounds.

Next, it is preferable to use 0.05-30 weight part of hardening | curing agents with respect to 100 volume parts of heat conductive adhesive compositions. If the curing agent is less than 0.05 parts by weight or more than 30 parts by weight, the adhesive strength can be reduced. Examples of the curing agent of the present invention as described above are polyfunctional acrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, glyceryl propoxylated triacrylate, allyl acrylate and allyl ether (Allyl Ether Although there exist curable monomers, such as), it is not limited only to these.

Next, the pressure-sensitive adhesive composition according to the present invention includes a hybrid filler in which carbon fiber (CF) and particulate filler are mixed to have high thermal conductivity while having electrical insulation.

First, the particulate filler material is a metal oxide such as aluminum oxide (Alumina or Al ₂ O ₃ ), magnesium oxide (MgO), zinc oxide (ZnO) or boron nitride (BN), aluminum nitride (AlN), silicon carbon ( Ceramic materials such as SiC). In addition, in addition to thermal conductivity such as aluminum hydroxide (Al (OH) ₃ ) or magnesium hydroxide (Mg (OH) ₂ ), a material containing flame resistance may be used. In addition, graphite or carbon nanotubes may be used. CNT) and graphene may also be used as the thermally conductive material. At this time, in order to increase the thermal conductivity, the particle-shaped ceramic particle diameter is mixed and used in various ways. In other words, the particulate ceramic filler is preferably used by mixing two or more of those having a particle diameter of 1 to 100 µm.

In addition, in the present invention, a silane coupling agent that has a high thermal conductivity, has a specific gravity, and has a specific gravity, and can easily form a thermal conductive network in a fibrous form, can be used a silane coupling agent that has a surface treatment to have a carbon-carbon double bond on the surface of the particulate filler. have. In this case, the silane coupling agent content is preferably used 0.01 to 5.0 parts by volume based on 100 parts by volume of the thermally conductive adhesive composition.

The silane coupling agent of the present invention is composed of an organic functional group and a hydrolyzable group. As described above, the silane coupling agent of the present invention functions as an interfacial binder of the particulate filler because it has a reactor capable of bonding with an organic functional group in the molecule. Here, a hydrolyzable group is chemically and thermally stable because many functional groups, such as a vinyl group, an epoxy group, a methacryloxy group, and an amino group, are synthesize | combined, and an organic functional group couple | bonds with a silicon (Si) atom by an alkylene group.

The use of a large amount of particulate ceramic filler can improve the processability by reducing acidic reactions that can occur between acidic or basic fillers and acrylic or acrylic adhesive resins. That is, the acidic acid reaction may increase the viscosity to cause workability problems. The silane coupling agent according to the present invention offsets the phonon scattering phenomenon occurring at the interface between the particulate filler and the acrylic adhesive resin to reduce the thermal resistance. give. In addition, when the silane coupling agent having a carbon-carbon double bond is used for surface treatment in the particulate filler, it is possible to polymerize with the acrylic adhesive resin to improve dispersibility and increase the thermal conductive network.

Next, the above-described thermally conductive adhesive composition of the present invention may be made of a thermally conductive adhesive sheet. At this time, it is preferable that the density of a thermally conductive adhesive sheet is 5.0 g / cm <3> or less, and although the thickness of a sheet is not limited, it is preferable that it is 50 micrometers-2 mm. If the thickness is less than 50 μm, the heat transfer contact area becomes small, making it difficult to achieve sufficient heat transfer between the heating element and the heat dissipation sheet. This can take a long time.

Hereinafter, the process of manufacturing an adhesive sheet using the above-mentioned heat conductive adhesive composition of this invention shall be described and demonstrates an Example.

First, the carbon fiber and particulate filler constituting the hybrid filler of the present invention uses a material having the properties shown in Table 1 below.

TABLE 1

Referring to Table 1, in the present invention, pitch-based carbon fibers having an apparent density of 0.5 g / cm 3, a thermal conductivity of 50 W / mK or more, a diameter of 10 μm, and a length of 200 μm are used, and the particulate filler is aluminum oxide. (Al ₂ O ₃ ) is used.

Example 1

Viscosity 1000 cP first syrup was prepared by photopolymerization of 90 parts by weight of 2-ethyl hexyl acrylate and 10 parts by weight of polar monomer acrylic acid in a 1 liter glass reactor.

Next, 0.01 parts by weight of igacure-819 as a photoinitiator and 0.1 parts by weight of 1,6-hexadiol diacrylate (HDDA) as a crosslinking agent are mixed with respect to 100 parts by weight of the first syrup, followed by stirring sufficiently to prepare a second syrup. .

Next, 10 parts by volume of pitch-based carbon fiber DKD (BP / Amoco Co., USA) having a thermal conductivity of 50 W / mK or more with respect to 100 parts by volume of the entire pressure-sensitive adhesive composition was sufficiently stirred, followed by Al as a particulate filler. by mixing ₂ O ₃ (40 ㎛) 40 parts by to prepare a pressure-sensitive adhesive composition was stirred until the mixture became sufficiently uniform. Here, 'sufficiently' means the degree to which the uniformity of the particles is close to 1: 1, and thus the time or stirring speed may vary depending on the situation.

Next, the pressure-sensitive adhesive composition was degassed under reduced pressure using a vacuum pump, and then prepared into a thermally conductive adhesive sheet having a thickness of more than 0.3 mm and less than 1.5 mm using a doctor blade in 100 μm of a silicone coated PET film. At this time, the adhesive sheet is cured by irradiating with light for 10 minutes using a UV lamp.

Example 2

A thermally conductive adhesive sheet was obtained in the same manner as in Example 1 except that 30 parts of pitch carbon fiber and 20 parts of particulate filler Al ₂ O ₃ (40 μm) were used.

Example 3

A thermally conductive adhesive sheet was obtained in the same manner as in Example 1 except that 40 parts of pitch carbon fiber and 10 parts of particulate filler Al ₂ O ₃ (40 μm) were used.

Example 4

The above process was carried out except that 10 parts of pitch carbon fiber and methacryloxy silane coupling agent KBM-503 ((Shinetsu, Japan) 0.5 parts of surface treated filler Al ₂ O ₃ (40 μm) were used. It carried out by the same method as Example 1, and obtained the thermal conductive adhesive sheet.

Example 5

Except that 30 parts of pitch carbon fiber and methacryloxy silane coupling agent KBM-503 ((Shinetsu, Japan) 20 parts of particulate filler Al ₂ O ₃ (40 μm) surface-treated A thermally conductive adhesive sheet was obtained in the same manner as in Example 1 above.

Comparative Example 1

A thermally conductive adhesive sheet was obtained in the same manner as in Example 1 except that only a single filler having only 50 parts by volume of carbon fiber was used.

Comparative Example 2

A thermally conductive adhesive sheet was obtained in the same manner as in Example 1 except that 50 parts by volume of particulate filler Al ₂ O ₃ (40 μm) was used.

Comparative Example 3

A thermally conductive adhesive sheet was obtained in the same manner as in Example 1, except that 30 parts by volume of pitch-based carbon fiber and 20 parts by volume of particulate filler AlN (3.5 μm) were used.

Comparative Example 4

The same method as in Example 1 except that 30 parts by volume of PAN-based carbon fiber K223 (Mitsubishi Chemical Co., Japan) having a thermal conductivity of 15 W / mK and 20 parts by volume of particulate filler Al ₂ O ₃ (40 μm) were used. It carried out by the above and obtained the heat conductive adhesive sheet.

The volume and the surface treatment according to the carbon fiber or particulate filler particle size used in Examples and Comparative Examples are shown in the following [Table 2].

TABLE 2

Next, the physical properties of the thermally conductive adhesive sheets prepared in Examples 1 to 5 and Comparative Examples 1 to 4 were measured by the following method, and the results are shown in the following [Table 3].

1. Thermal conductivity test

1) Thermal diffusivity: The laser scintillation method was used, and was measured using ULVAC TC-7000.

2) Density: Measured using Electronic Densimeter MD-300S of Alfa Mirage.

3) Specific heat: Specific heat was measured using a standard sample of sapphire by DSC of TA.

The thermal conductivity was obtained through the following [Equation 1].

[Equation 1]

       k = α · ρ · Cp

(k = thermal conductivity, α = thermal diffusivity, ρ = density, Cp = specific heat)

2. Adhesion Test

       Aluminum was used as an adherend and measured using a texture analyzer based on JIS Z1541.

[Table 3]

As shown in Table 3, in Examples 1 to 5 in which pitch-based carbon fibers and particulate fillers were mixed, the thermal conductivity was higher than that of Comparative Examples 1 and 2, in which carbon fibers and particulate fillers were not mixed. Indicated.

Next, when Example 5 using the surface-treated particulate filler was compared with Comparative Example 3, Example 5 showed high thermal conductivity.

In addition, when comparing Example 2 using the pitch-based carbon fiber and Comparative Example 4 using the PAN-based carbon fiber, the case of Example 2 according to the present invention showed a high thermal conductivity.

As described above, the thermally conductive adhesive composition according to the present invention is prepared by mixing a hybrid filler in which carbon fibers and particulate filler are mixed with an acrylic adhesive resin to prepare a thermally conductive adhesive sheet, whereby the filler is uniformly dispersed in thermal conductivity. It is possible to produce a pressure-sensitive adhesive resin to improve the, and maintain excellent adhesive properties.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments and can be modified in various forms, and having ordinary skill in the art to which the present invention pertains. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1 is a schematic view showing a pressure-sensitive adhesive composition according to the prior art.

2 is a schematic view showing an adhesive composition according to the present invention.

Claims (13)

Acrylic adhesive resins; And A thermally conductive adhesive composition comprising a hybrid filler in which carbon fiber to particulate filler is mixed in a volume ratio of 1: 4 to 4: 1. The method of claim 1, The content of the acrylic pressure-sensitive adhesive resin based on 100 parts by volume of the thermally conductive adhesive composition is 20 to 95 parts by volume is added, the hybrid filler is a heat conductive adhesive composition, characterized in that 5 to 80 parts by volume is added. The method of claim 1, The said acrylic adhesive resin mixed 0-40 weight part of polar monomers which can copolymerize with the said monomer with respect to 100 weight part of (meth) acrylic acid ester monomers which have a C1-C12 alkyl group. The heat conductive adhesive composition characterized by the above-mentioned. The method of claim 3, wherein The (meth) acrylic acid ester monomers are ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethyl A heat conductive adhesive composition, characterized in that at least one selected from the group consisting of hexyl (meth) acrylate and isononyl (meth) acrylate. The method of claim 1, The acrylic adhesive resin is a heat conductive adhesive composition, characterized in that the ultraviolet curable type. The method of claim 1, The thermally conductive adhesive composition, characterized in that the carbon fiber has a thermal conductivity of 50 W / mK or more. The method of claim 1, The carbon fiber is a heat conductive adhesive composition, characterized in that the pitch-based (Pitch) carbon fiber. The method of claim 1, A thermally conductive pressure-sensitive adhesive composition, characterized in that the apparent density of the carbon fiber and the particulate filler is 3.0 g / cm 3 or less. The method of claim 1, The particulate filler is aluminum oxide (Alumina or Al ₂ O ₃ ), magnesium oxide (MgO), zinc oxide (ZnO), boron nitride (BN), aluminum nitride (AlN), silicon carbon (SiC), aluminum hydroxide (Al (OH) ₃ ), magnesium hydroxide (Mg (OH) ₂ ), graphite (Graphite), carbon nanotubes (Carbon Nano Tube; CNT) and thermal conductivity, characterized in that it comprises one or more selected from graphene (Graphene) Pressure-sensitive adhesive composition. The method of claim 1, A thermally conductive adhesive composition, wherein the particulate filler is surface treated with 0.01 to 5.0 parts by volume of a silane coupling agent based on 100 parts by volume of the thermally conductive adhesive composition. The method of claim 10, The silane coupling agent has a thermally conductive adhesive composition, characterized in that it has a carbon-carbon double bond. The heat conductive adhesive sheet which consists of a composition of Claim 1, and whose density is 5.0 g / cm <3> or less. Photopolymerizing the acrylate and the polar monomer acrylic acid in a glass reactor to produce a first liquid acrylic syrup; Preparing a second liquid acrylic syrup by mixing a photoinitiator and a crosslinking agent with the liquid acrylic syrup, followed by stirring; Preparing a pressure-sensitive adhesive composition by adding a hybrid filler in which a carbon fiber-to-particulate filler is mixed in a volume ratio of 1: 4 to 4: 1 to the second acrylic syrup, and then stirring the mixture; Preparing the pressure-sensitive adhesive composition layer on the silicon-coated PET film after degassing the pressure-sensitive adhesive composition using a vacuum pump; And Method of manufacturing a thermally conductive adhesive sheet comprising the step of curing the pressure-sensitive adhesive composition layer using a UV lamp.

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