JP2011184668A - Thermally conductive thermoplastic adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermally conductive thermoplastic adhesive composition having high thermal conductivity, intense adhesive strength and high adhesive reliability used for laminating glass panels for plasma displays, heat radiation plates for electronic equipment and the like. <P>SOLUTION: The thermally conductive thermoplastic adhesive composition comprises (A) an epoxy resin having 1.5-2.2 average functional groups, (B) at least one kind of compounds selected from the group consisting of amine-based compounds, phenol-based compounds and thiol-based compounds each having 2 functional groups capable of reacting with an epoxy group, and (C) graphite. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a thermoplastic adhesive composition excellent in thermal conductivity used for bonding a glass panel of a plasma display or a heat sink of an electronic device, and more specifically, high thermal conductivity, high adhesive strength, The present invention relates to an adhesive composition having high adhesion reliability and excellent dismantling properties.

Plasma display panels, high-brightness LED substrates, high-performance CPUs, and the like generate a large amount of heat, so methods for lowering their temperatures are being studied. In particular, in the plasma display panel, if temperature unevenness occurs in the glass panel due to heat generation, it causes uneven color in the screen, and thus it is necessary to lower the temperature by some method.

In general, as a method for lowering the temperature of a plasma display panel, a method in which a glass panel and a metal frame such as aluminum or iron are bonded with a double-sided adhesive tape having thermal conductivity is employed. The heat generated in the glass panel is conducted to the metal frame by the double-sided adhesive tape having thermal conductivity to dissipate the heat, thereby suppressing temperature rise in the glass panel, suppressing temperature non-uniformity, and uneven color of the screen. Can be suppressed.

For example, Patent Document 1 describes a heat conductive thermoplastic pressure-sensitive adhesive composition in which graphite is mixed with liquid rubber, styrene rubber or amorphous olefin resin, and tackifier resin, and a heat conductive sheet using the same. ing. The heat conductive sheet described in Patent Document 1 has high heat conductivity and is said to be suitable for bonding a glass panel of a plasma display, a heat radiating plate of an electronic device, and the like. Furthermore, the heat conductive sheet described in Patent Document 1 also has a feature that it can be easily disassembled by heating at the time of repair of the product or after the end of the product life cycle.

Plasma displays are becoming larger year by year and the amount of heat generated is also increasing. In addition, plasma displays used in home TVs repeatedly generate heat from use several times a day and cool down when they are turned off, so they have high adhesive reliability even after extremely severe heat history. Must be able to demonstrate In addition, the usage environment of plasma displays is diversifying, such as being expected to be used outdoors in direct sunlight.
The thermal conductive sheet described in Patent Document 1 has a problem that high adhesion reliability under such severe conditions cannot be obtained. Therefore, there has been a demand for an adhesive composition that has high thermal conductivity, high adhesive strength, high adhesive reliability, and excellent dismantling properties.

International Publication No. 07/148729 Pamphlet

The present invention provides a thermally conductive thermoplastic adhesive composition having high thermal conductivity, high adhesive strength, and high adhesion reliability, which is used for bonding a glass panel of a plasma display or a heat sink of an electronic device. The purpose is to do.

The present invention comprises (A) an epoxy resin having an average functional group number of 1.5 to 2.2, (B) an amine compound having two functional groups capable of reacting with an epoxy group, a phenol compound, and a thiol compound. A thermally conductive thermoplastic adhesive composition containing at least one compound selected from the group and (C) graphite.
The present invention is described in detail below.

Selected from the group consisting of (A) an epoxy resin having an average functional group number of 1.5 to 2.2, and (B) an amine compound having two functional groups capable of reacting with an epoxy group, a phenol compound, and a thiol compound. The cured product of the adhesive composition containing at least one kind of compound has a unique property that it has high adhesiveness and adhesion reliability inherent to an epoxy resin, and also has thermoplasticity. The inventor of the present invention can exhibit high thermal conductivity, high adhesive strength, and high adhesive reliability while the thermally conductive thermoplastic adhesive composition in which (C) graphite is further added to the adhesive composition. The present invention has been completed by finding that it can be easily disassembled by heating at the time of repair of the product or after the end of the product life cycle.

The thermally conductive thermoplastic adhesive composition of the present invention comprises (A) an epoxy resin having an average functional group number of 1.5 to 2.2, and (B) an amine compound having two functional groups capable of reacting with an epoxy group. And at least one compound selected from the group consisting of phenolic compounds and thiol compounds, and (C) graphite.

The epoxy resin having an average functional group number of 1.5 to 2.2 is an epoxy resin or an epoxy resin containing a bifunctional epoxy resin as a main component and a monofunctional epoxy resin or a trifunctional or higher functional epoxy resin as necessary. It means a mixture. If the average number of functional groups of the epoxy resin is less than 1.5, sufficient adhesive strength and adhesive reliability cannot be obtained, and if it exceeds 2.2, the thermoplasticity will be reduced, and it will be disassembled even when heated. It becomes difficult. The preferable lower limit of the average number of functional groups of the epoxy resin is 1.8, and the preferable upper limit is 2.
In this specification, the average number of functional groups means the number of epoxy groups per molecule of epoxy resin.

Examples of the bifunctional epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bifunctional phenol novolac type epoxy resin, bisphenol AD type epoxy resin, biphenyl type epoxy resin, and bifunctional naphthalene. Type epoxy resin, bifunctional alicyclic epoxy resin, difunctional glycidyl ester type epoxy resin such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, dimer acid diglycidyl ester, diglycidyl aniline, diglycidyl toluidine, etc. Bifunctional glycidylamine type epoxy resin, bifunctional heterocyclic epoxy resin, bifunctional diarylsulfone type epoxy resin, hydroquinone diglycidyl ether, 2,5-di-tert-butylhydroquinone diglycidyl Hydroquinone type epoxy resins such as ether and resorcin diglycidyl ether, bifunctional alkylene glycidyl ether compounds such as butanediol diglycidyl ether, butenediol diglycidyl ether, butynediol diglycidyl ether, and 1,3-diglycidyl-5 Bifunctional glycidyl group-containing hydantoin compounds such as 1,5-dialkylhydantoin, 1-glycidyl-3- (glycidoxyalkyl) -5,5-dialkylhydantoin, and 1,3-bis (3-glycidoxypropyl) Examples thereof include bifunctional glycidyl group-containing siloxanes such as -1,1,3,3-tetramethyldisiloxane and α, β-bis (3-glycidoxypropyl) polydimethylsiloxane, and modified products thereof. These bifunctional epoxy resins may be used alone or in combination of two or more. Of these, bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferable from the viewpoint of reactivity and workability.

The bifunctional epoxy resin is a main component of the epoxy resin.
The minimum with preferable content of the said bifunctional epoxy resin which occupies in the said epoxy resin is 50 weight%. When the content of the bifunctional epoxy resin is less than 50% by weight, it may be difficult to achieve both sufficient adhesive strength, adhesion reliability, and disassembly. The minimum with more preferable content of the said bifunctional epoxy resin is 80 weight%.

The said monofunctional epoxy resin has a role as a reactive diluent, and has a role which adjusts the viscosity of the heat conductive thermoplastic adhesive composition of this invention. However, since blending a large amount of the above monofunctional epoxy resin may impair the adhesive strength and adhesive reliability of the heat conductive thermoplastic adhesive of the present invention, the blending should be within a range that does not impair the purpose of the present invention. .
Examples of the monofunctional epoxy resin include tert-butylphenyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, Monoglycidyl compounds such as 1- (3-glycidoxypropyl) 1,1,3,3,3-pentamethyldisiloxane, N-glycidyl-N, N-bis [3- (trimethoxysilyl) propyl] amine And monoalicyclic epoxy compounds such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. These monofunctional epoxy resins may be used alone or in combination of two or more.

By using the above-mentioned trifunctional or higher epoxy resin in combination, it is possible to further improve the adhesion strength and adhesion reliability of the heat conductive thermoplastic adhesive composition of the present invention. However, if a large amount of the above-mentioned trifunctional or higher epoxy resin is blended, the disassembling property of the thermally conductive thermoplastic adhesive composition of the present invention may be impaired. Therefore, the blending should be within a range that does not impair the purpose of the present invention. .
The tri- or higher functional epoxy resin may be, for example, a tri- or higher functional phenol novolac type epoxy resin, a tri- or higher functional alicyclic epoxy resin, a tri- or higher functional glycidyl ester type epoxy resin, tetraglycidyl diaminodiphenylmethane, Trifunctional or higher glycidylamine type epoxy resins such as glycidyl-p-aminophenylmethane, triglycidyl-m-aminophenylmethane, tetraglycidyl-m-xylylenediamine, trifunctional or higher heterocyclic epoxy resins, 3 More than trifunctional diaryl sulfone type epoxy resin, trifunctional or higher alkylene glycidyl ether compounds such as glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, and more than trifunctional group And glycidyl group-containing hydantoin compound, trifunctional or more glycidyl group-containing siloxane, and modified products thereof. These trifunctional or higher functional epoxy resins may be used alone or in combination of two or more.

The heat conductive thermoplastic adhesive composition of the present invention contains graphite.
The graphite plays a role as a heat conductive material.
The graphite is not particularly limited, and may be natural graphite or artificial graphite, for example. Among these, artificial graphite is preferable because of its high purity and low ash content.

The preferable lower limit of the average particle diameter of the graphite is 0.5 μm, and the preferable upper limit is 250 μm. When the average particle size of the graphite is less than 0.5 μm, the viscosity of the thermally conductive thermoplastic adhesive of the present invention is increased, and the coating property may be deteriorated. When the average particle size is more than 250 μm, the thermal conductivity is Although it becomes better, the adhesion reliability may be lowered. A more preferable lower limit of the average particle diameter of the graphite is 1 μm, a more preferable upper limit is 200 μm, a further preferable lower limit is 5 μm, and a further preferable upper limit is 150 μm.
In the present specification, the average particle diameter of graphite means an average particle diameter measured by a laser diffraction method.

The shape of the graphite is not particularly limited, but when a scaly shape, a needle shape, or a mixture thereof is used, both the applicability of the thermally conductive thermoplastic adhesive of the present invention and the adhesion reliability after adhesion can be achieved. it can.
Especially, it is preferable to contain the graphite whose average aspect-ratio is 1.1-30. The graphite having such an average aspect ratio can be more easily brought into contact with each other in the epoxy resin, and can exhibit higher thermal conductivity. Furthermore, anisotropic thermal conductivity can be exhibited by aligning the major axis direction of graphite.
When the average aspect ratio of the graphite is less than 1.1, the effect of improving thermal conductivity and anisotropic thermal conductivity may not be obtained. When the average aspect ratio exceeds 30, the thermal conductive thermoplastic adhesive of the present invention Viscosity increases and coatability may deteriorate. A more preferred lower limit of the aspect ratio of the graphite is 1.2, a more preferred upper limit is 20, a further preferred lower limit is 1.5, a still more preferred upper limit is 10, a particularly preferred lower limit is 2, and a particularly preferred upper limit is 5. is there.

In the present specification, the average aspect ratio of graphite means an average value of aspect ratios obtained from 50 graphite particle images randomly extracted by photographing graphite with an electron microscope. The aspect ratio of graphite is the ratio of the maximum length of each graphite particle image and the ratio of the vertical length to the maximum length, that is, the aspect ratio = (maximum length) / (vertical length relative to the maximum length). Represents the degree of condition. Here, the vertical length with respect to the maximum length is the minimum value that can be taken.

The graphite has a preferable lower limit of dibutyl phthalate (DBP) oil absorption of 30 mL / 100 g and a preferable upper limit of 200 mL / 100 g. When the DBP oil absorption amount of the graphite is less than 30 mL / 100 g, the adhesion reliability may be lowered, and when it exceeds 200 mL / 100 g, the viscosity of the thermally conductive thermoplastic adhesive of the present invention may become too high. is there. The more preferable lower limit of the DBP oil absorption of the graphite is 50 mL / 100 g, the more preferable upper limit is 160 mL / 100 g, the still more preferable lower limit is 60 mL / 100 g, and the still more preferable upper limit is 140 mL / 100 g.

The blending amount of the graphite is preferably 30% by weight and preferably 75% by weight with respect to the total mass of the heat conductive thermoplastic adhesive of the present invention. When the blending amount of the graphite is less than 30% by mass, the thermal conductivity may be insufficient. When the blending amount exceeds 75% by weight, the viscosity of the thermally conductive thermoplastic adhesive of the present invention increases, Workability may deteriorate. The more preferable lower limit of the compounding amount of the graphite is 35% by weight, the more preferable upper limit is 65% by weight, the still more preferable lower limit is 40% by weight, and the still more preferable upper limit is 60% by weight.

The thermally conductive thermoplastic adhesive composition of the present invention further comprises at least one selected from the group consisting of an amine compound having two functional groups capable of reacting with an epoxy group, a phenol compound, and a thiol compound. Contains compounds. These compounds act as curing agents for the epoxy resin. By using a curing agent having two functional groups capable of reacting with an epoxy group, the resulting cured product does not become a network polymer but a linear polymer, so that the epoxy resin cured product has high adhesion reliability. It is possible to exhibit high thermoplasticity, that is, excellent dismantling properties.

Examples of the amine compound having two functional groups capable of reacting with the epoxy group include piperazine, dodecylamine, benzylamine, dimethylaminopropylamine and the like.
Examples of the phenolic compound having two functional groups capable of reacting with the epoxy group include mononuclear aromatic dihydroxy compounds having one benzene ring such as catechol, resorcin, and hydroquinone, and bis (4-hydroxyphenyl). Bisphenols such as propane (bisphenol A), bis (4-hydroxyphenyl) methane (bisphenol F), bis (4-hydroxyphenyl) ethane (bisphenol AD), compounds having a condensed ring such as dihydroxynaphthalene, diallyl resorcin , Bifunctional phenol compounds into which an allyl group such as diallyl bisphenol A and triallyl dihydroxy biphenyl has been introduced, and dibutyl bisphenol A.
Examples of the thiol compound having two functional groups capable of reacting with the epoxy group include ethylene glycol bisthioglycolate and ethylene glycol bisthiopropionate.
These amine compounds, phenol compounds and thiol compounds may be used alone or in combination of two or more.

The amine compound, phenol compound and thiol compound are preferably liquid or semi-solid at room temperature. Moreover, the minimum with the preferable molecular weight of the said amine compound, a phenol type compound, and a thiol type compound is 50, a preferable upper limit is 1000, a more preferable minimum is 100, and a more preferable upper limit is 500.

Although the compounding quantity of the said amine compound, a phenolic compound, and a thiol type compound is not specifically limited, The preferable minimum with respect to 1 equivalent of the said epoxy resin is 0.8 equivalent, A preferable upper limit is 1.2 equivalent, A more preferable minimum is 0. 0.9 equivalent, and a more preferable upper limit is 1.1 equivalent.

The heat conductive thermoplastic adhesive composition of the present invention may further contain particles made of a thermoplastic resin. By containing the particles made of the thermoplastic resin, impact resistance and disassembly are improved.
Although the particle diameter of the particle | grains which consist of the said thermoplastic resin is not specifically limited, 1-200 micrometers is preferable. Particles made of the above thermoplastic resin having such a particle size can be dispersed in the adhesive composition in the same manner as ordinary fillers.
Examples of the particles made of the thermoplastic resin include polyethylene powder, polyvinyl chloride powder, thermoplastic polyurethane powder (TPU), and the like. The particles made of these thermoplastic resins may be used alone or in combination of two or more. Of these, thermoplastic polyurethane powder (TPU) is preferred.

Although the compounding quantity of the particle | grains which consist of the said thermoplastic resin is not specifically limited, A preferable minimum is 10 weight% and a preferable upper limit is 50 weight%. When the blending amount of the thermoplastic resin particles is less than 10% by weight, the effect of improving impact resistance and disassembly may not be obtained. When the blending amount exceeds 50% by weight, the heat conductive heat of the present invention is not obtained. The viscosity of the plastic adhesive can be very high. The upper limit with more preferable compounding quantity of the particle | grains which consist of the said thermoplastic resin is 30 weight%.

The thermally conductive thermoplastic adhesive composition of the present invention is generally an epoxy, such as a curing accelerator, a silane coupling agent, an antifoaming agent, a flame retardant, a dispersant, an antioxidant, an anti-aging agent, and a stabilizer. You may contain the component added to a resin composition.

The manufacturing method of the heat conductive thermoplastic adhesive composition of this invention is not specifically limited, A conventionally well-known method is employable.

The thermally conductive thermoplastic adhesive composition of the present invention can exhibit high thermal conductivity, high adhesive strength, and high adhesive reliability, and can be easily heated by heating during product repair or after the product life cycle is completed. Can be dismantled.
The thermally conductive thermoplastic adhesive composition of the present invention can be used for applications in which a member having a large calorific value, such as a plasma display panel, a high-brightness LED substrate, or a high-performance CPU, is bonded and the heat dissipation is promoted. Especially, it is suitable as an adhesive for plasma display panels used for adhesion | attachment with the glass panel and metal frame in a plasma display panel.
The adhesive for plasma display panels which consists of the heat conductive thermoplastic adhesive composition of this invention is also one of this invention.

The thermally conductive thermoplastic adhesive composition of the present invention is directly applied to a member to be bonded and used for bonding. In addition, the thermally conductive thermoplastic adhesive composition of the present invention can be formed in any shape on a substrate such as a plastic film or paper that has been subjected to a release treatment using a conventionally known apparatus such as a die coater or a press. After coating, it can be transferred to the place to be bonded. The heat conductive thermoplastic adhesive composition of the present invention can also be suitably used in the form of a heat conductive sheet.

The coating method of the heat conductive thermoplastic adhesive composition of the present invention is not particularly limited. For example, in the case of applying uniformly to a flat member such as a glass panel of a plasma display, a curtain coater, a roll coater, etc. Can be used. In addition, when it is necessary to apply a specific shape such as a dot shape, a bead shape, or a spiral shape, an applicator consisting of a melting tank, a heat insulating hose, a coating nozzle, etc. is used, and it is required from the coating nozzle. Can be applied to the site.

When the heat conductive thermoplastic adhesive composition of the present invention contains graphite having an average aspect ratio of 1.1 to 30, when applying the heat conductive thermoplastic adhesive composition of the present invention. High anisotropic heat conductivity can be exhibited by applying a shear stress to orient the graphite. For example, when performing adhesion between a glass panel and a metal frame in a plasma display panel, by applying so that graphite is oriented in a direction perpendicular to the glass panel surface, high anisotropic heat conductivity is exhibited, The surface temperature of the glass panel can be made uniform more quickly.

The coating method for applying shear stress to orient the graphite is not particularly limited. For example, a method of performing bead coating while relatively moving the position of the coating nozzle and the coating surface such as a glass panel in the surface direction, A method of coating while deforming the adhesive composition in the direction parallel to the coating surface, such as a method of coating by a roll coating method in which the peripheral speed of the coating roll and the moving speed of the coating surface are different. Can be mentioned. In addition, after the block-shaped body or sheet-shaped body having a certain thickness is molded with the adhesive composition of the present invention, the molded body is stretched by passing it once or a plurality of times between two rolls. There is a method of performing the treatment. The thermally conductive thermoplastic adhesive composition of the present invention is particularly easy to orient graphite because of its low viscosity during melt coating.

According to the present invention, a thermally conductive thermoplastic adhesive composition having high thermal conductivity, high adhesive strength, and high adhesive reliability, which is used for bonding a glass panel of a plasma display or a heat sink of an electronic device. Can be provided.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

Example 1
1 part by weight of tritolylphosphine (“TOTP” manufactured by Hokuko Chemical Co., Ltd.) as a curing accelerator with respect to 100 parts by weight of a bifunctional epoxy resin (“AER260” manufactured by Asahi Ciba, bisphenol A type epoxy resin, number average molecular weight 380) Was added and dissolved at 100 ° C., and 102 parts by weight of Ultrait P (manufactured by Honshu Chemical Co., Ltd., main component dibutyl bisphenol A) was added and mixed as a curing agent. Further, 160 parts by weight of G150 (manufactured by Chuetsu Graphite Industries Co., Ltd., artificial graphite, average particle diameter measured by laser diffraction method, about 100 μm, average aspect ratio 3.4) as graphite is added and mixed, and heat conductive thermoplasticity. An adhesive composition was obtained.
The obtained thermally conductive thermoplastic adhesive composition was coated on a polyethylene terephthalate (PET) separator using a coating applicator so that the thickness after heat curing was 1 mm, and then in a 130 ° C. oven. Heat curing was performed for 1 hour to obtain a heat conductive sheet having a thickness of 1 mm.

(Example 2)
The same method as in Example 1 except that 160 parts by weight of UF-G30 (manufactured by Showa Denko KK, artificial graphite, average particle diameter measured by laser diffraction is about 10 μm, average aspect ratio 3.6) was used as graphite. Thus, a heat conductive thermoplastic adhesive composition and a heat conductive sheet were obtained.

(Example 3)
Tetramethylammonium chloride (manufactured by Nippon Specialty Chemicals Co., Ltd.) as a curing accelerator for 100 parts by weight of a bifunctional epoxy resin (AER260 manufactured by Asahi Ciba, bisphenol A type epoxy resin, number average molecular weight 380) 0.1 After adding parts by weight and dissolving at 100 ° C., 58 parts by weight of ethylene glycol bisthioglycolate (“EGTG” manufactured by Sakai Chemical Co., Ltd.) as a curing agent was added and mixed. Further, 129 parts by weight of G150 as graphite was added and mixed to obtain a heat conductive thermoplastic adhesive composition.
A heat conductive sheet was produced in the same manner as in Example 1 except that the obtained heat conductive thermoplastic adhesive composition was used.

(Comparative Example 1)
Claprene LIR-290 (manufactured by Kuraray Co., Ltd., liquid hydrogenated polyisoprene rubber, weight average molecular weight 25000, hydrogenation rate of about 90%) 600 parts by weight, Kraton G1650 (manufactured by Kraton Polymer Japan Co., Ltd.) 200 parts by weight of SEBS (styrene / (ethylene / butylene) weight ratio = 29/71), 200 parts by weight of YS Polystar T145 (Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 145 ° C.) which is a tackifier resin, and IRGANOX 1010 ( A rubber composition was prepared by mixing 10 parts by weight of a hindered phenol anti-aging agent manufactured by Ciba Specialty Chemicals Co., Ltd. at 180 ° C. for 4 hours.
To the obtained rubber composition, 826 parts by weight of G150 as graphite was further added and mixed to obtain an adhesive composition.

(Comparative Example 2)
100 parts by weight of bifunctional epoxy resin ("AER260" manufactured by Asahi Ciba, bisphenol A type epoxy resin, number average molecular weight 380), monofunctional epoxy resin ("ED509S" manufactured by Adeka, tert-butylphenyl, number average molecular weight 209) After 82 parts by weight and 1.5 parts by weight of tolylphosphine were added and dissolved at 100 ° C., 144 parts by weight of Ultrait P was added and mixed as a curing agent. Further, 268 parts by weight of G150 as graphite was added and mixed to obtain a heat conductive thermoplastic adhesive composition.
A heat conductive sheet was produced in the same manner as in Example 1 except that the obtained heat conductive thermoplastic adhesive composition was used.
In addition, the average number of functional groups of the used epoxy resin mixture is 1.4.

(Comparative Example 3)
Bifunctional epoxy resin ("AER260" manufactured by Asahi Chiba Co., Ltd., bisphenol A type epoxy resin, number average molecular weight 380) 100 parts by weight Trifunctional epoxy resin ("EP3950S" manufactured by Adeka Co., Ltd., number average molecular weight 277) 51 parts by weight After adding 2 parts by weight of tolylphosphine and dissolving at 100 ° C., 179 parts by weight of Ultrait P was added and mixed as a curing agent. Further, 272 parts by weight of G150 as graphite was added and mixed to obtain a heat conductive thermoplastic adhesive composition.
A heat conductive sheet was produced in the same manner as in Example 1 except that the obtained heat conductive thermoplastic adhesive composition was used.
In addition, the average functional group number of the used epoxy resin mixture is 2.4.

(Comparative Example 4)
The adhesive composition and heat were obtained in the same manner as in Example 1 except that Heidilite H-42M (made by Showa Denko KK, aluminum hydroxide, average particle diameter of about 1.1 μm by laser diffraction) was used instead of graphite. A conductive sheet was obtained.

(Comparative Example 5)
The adhesive composition and the heat conductive sheet were prepared in the same manner as in Example 1 except that AX-116 (manufactured by Micron, spherical alumina, average particle diameter measured by laser diffraction method was 20 μm) was used instead of graphite. Obtained.

(Evaluation)
About the heat conductive sheet obtained by the Example and the comparative example, it evaluated by the following method.
The results are shown in Table 1.

(1) Measurement of thermal conductivity A thermal conductive sheet was punched into a circle having a diameter of 50 mm, and the thermal conductivity in the thickness direction at 23 ° C was measured by a method based on ASTM E 1530.
Ten heat conductive sheets are stacked, sliced to a thickness of 1 mm in the surface direction and the vertical direction, the sliced sheet is punched into a circle having a diameter of 50 mm, and the horizontal direction at 23 ° C. is obtained by a method in accordance with ASTM E 1530. The thermal conductivity of was measured.

(2) Evaluation of adhesion reliability The heat conductive sheet was cut into a width of 2.5 cm and a length of 2.5 cm and heated on a hot plate at 130 ° C., the width was 2.5 cm, the length was 10 cm, and the thickness was 0.5 mm. Placed on an aluminum plate. Similarly, another aluminum plate having the same size and thickness of 0.5 mm, which has been heated on a hot plate at 130 ° C. in advance, is placed so as to cover the heat conductive sheet, and lightly pressed and cooled. A test piece was prepared.
The obtained test piece was left to stand for 168 hours in an atmosphere of 80 ° C. and a relative humidity of 60%, and a deterioration promotion test was conducted. A peel test was performed on the test piece after the deterioration acceleration test using a tensile tester so that the thin aluminum plate was peeled 180 degrees, and the strength at the time of peeling was measured.

(3) Evaluation of disassembly property A test piece was prepared in the same manner as in (2) Adhesion reliability.
A temperature of 130 ° C. was applied to the obtained test piece, and both ends of the test piece were pulled with both hands wearing gloves before the temperature was lowered to confirm the dismantling property. The case where the two pieces of aluminum plate could be easily separated was evaluated as “◯”, and the case where a strong force was required for disassembling or difficult to disassemble was evaluated as “×”.

ADVANTAGE OF THE INVENTION According to this invention, it can provide the adhesive composition which has high heat conductivity, high adhesive strength, high adhesive reliability, and is excellent also in demolition property.

Claims (7)

(A) an epoxy resin having an average functional group number of 1.5 to 2.2,
(B) at least one compound selected from the group consisting of an amine compound having two functional groups capable of reacting with an epoxy group, a phenol compound and a thiol compound, and
(C) A thermally conductive thermoplastic adhesive composition characterized by containing graphite. The heat conductive thermoplastic adhesive composition according to claim 1, wherein the graphite content is 30 to 75% by weight. The heat conductive thermoplastic pressure-sensitive adhesive composition according to claim 1 or 2, wherein the graphite is artificial graphite. The heat conductive thermoplastic adhesive composition according to claim 1, 2 or 3, wherein the graphite has a dibutyl phthalate oil absorption of 30 to 200 mL / 100 g. The heat conductive thermoplastic adhesive composition according to claim 1, 2, 3, or 4, wherein the average particle diameter of graphite measured by a laser diffraction method is 0.5 to 250 µm. The heat conductive thermoplastic adhesive composition according to claim 1, 2, 3, 4, or 5, wherein the graphite has an average aspect ratio of 1.1 to 30. An adhesive for a plasma display panel, comprising the thermally conductive thermoplastic adhesive composition according to claim 1, 2, 3, 4, 5 or 6.