KR101703558B1 - Alumina and graphite composite including a thermally conductive resin composition and dissipative products - Google Patents

Abstract

The present invention relates to a thermoconductive composite resin composition comprising alumina powder and graphite powder having different average particle sizes and a heat dissipation structure using the same. The thermoconductive composite resin composition according to the present invention is formed by combining graphite powder and alumina powder, which are additives having excellent thermal conductivity, to a polymer resin having a low dielectric constant. When used as an adhesive, It is possible not only to induce effective heat radiation by reducing an air gap but also to reduce the shrinkage rate even after a long period of time and to maintain the shape even under stress so as to be useful for interfacial bonding of a heat dissipating structure. In addition, as a polymer composite material composition which can replace a conventional aluminum material heat sink, it is possible to reduce the weight as compared with aluminum, to have excellent corrosion resistance in a chemical environment and to greatly improve heat radiation characteristics, Film, a heat dissipation structure, and a heat conduction adhesive.

Description

TECHNICAL FIELD [0001] The present invention relates to a thermally conductive composite resin composition comprising alumina and graphite, and a heat dissipation structure using the same,

The present invention relates to a thermally conductive composite resin composition comprising alumina and graphite, and a heat dissipation structure using the same.

The technology using epoxy resin is widely used in the field of electronic parts. Development of composite polymer materials such as thermoconductive grease, thermally conductive adhesive, heat conductive sheet and the like is progressing in order to lower the contact thermal resistance between the surface where the metal and the ceramic are in contact and the part where the electronic component is attached. The thermally conductive grease helps heat conduction of metal parts such as heat exchangers and the thermally conductive adhesive is mainly used for bonding the cooling fin to the metal as the main body. The heat conductive sheet is sandwiched between the power transistor and the substrate, . In recent years, electronic products such as notebook computers and mobile phones have become more highly integrated and have a tendency to have high output specifications. In addition, as the substrate is becoming smaller and smaller, a large amount of heat is generated during operation of the apparatus. Which is a significant influence on the performance. Therefore, the heat dissipation problem of advanced electronic devices is becoming an important issue in product development for increasing the stability and reliability of the device more and more.

Epoxy resin or acrylic resin is widely used as a heat dissipation material for such electronic products. Especially, epoxy resin can be usefully developed as a heat-dissipating adhesive, and it maintains a constant high adhesive force even at high temperatures.

Also, in general metals, corrosion is promoted by moisture or air, which also has a considerable influence on the heat radiation characteristics. However, the adhesive using the epoxy resin can reduce the air gap existing at the interface between the heating element module and the metal to effectively prevent heat (heat radiation) as well as corrosion caused by moisture, . Further, even after a long period of time after the adhesion between the metal and the interface is performed, the shrinkage rate is small and the shape can be maintained even under stress.

Therefore, epoxy resin, which is one of the thermosetting resins used as matrix resin in various industries, has been used in various ranges due to its excellent physical properties. Conventional bisphenol type epoxy resins such as diglycidyl ether of bisphenol-A, DGEBA) and diglycidyl ether of bisphenol-F (DGEBF) are commercially available and widely used in a wide range of fields.

On the other hand, the thermal conductivity of general epoxy resin is very low (0.15 ~ 0.3 W / mK) compared to metal and ceramic. For this reason, a gas is mixed (formed into a foam) in a polymer matrix and used as a heat insulating material in various fields. However, attention has been paid to high thermal conductivity properties of polymer composite materials, focusing on electric insulation, moisture absorption, workability, corrosion resistance and other materials having excellent heat conduction characteristics.

However, conventionally developed resins are limited in their use as high-performance materials due to inherent high brittleness characteristics and problems such as deterioration in weatherability, so that it is difficult to use them as a structural material. Thus, epoxy resins Is required to develop.

Korean Patent Publication No. 10-2013-0122478

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has completed the present invention by developing a novel thermally conductive composite material capable of improving the low thermal conductivity of a polymer resin and having excellent adhesion to metal or ceramic materials.

Accordingly, an object of the present invention is to provide a thermally conductive composite resin composition applicable to a heat dissipation structure.

Another object of the present invention is to provide a method for producing the thermoconductive composite resin composition.

Another object of the present invention is to provide a heat-dissipating adhesive composition comprising the thermoconductive composite resin composition as an active ingredient.

Another object of the present invention is to provide a heat dissipation structure including the above-mentioned heat-dissipating adhesive composition.

In order to solve the above problems, the present invention provides a resin composition comprising: a polymer resin which is an acrylic resin or an epoxy resin; Curing agent; Alumina powder having an average particle size of 5 to 50 mu m; And a thermally conductive composite resin composition comprising graphite powder as an effective component.

In one embodiment of the present invention, the epoxy resin is selected from the group consisting of bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, cresol novolak epoxy resin, alkylphenol novolak epoxy A resin, a bisphenol type epoxy resin, a naphthalene type epoxy resin, a dicyclopentadiene type epoxy resin, a triglycidyl isocyanate epoxy resin and an acyclic epoxy resin.

In one embodiment of the present invention, the acrylic resin comprises a polymer or copolymer of methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate and hexyl acrylate Lt; / RTI >

In one embodiment of the present invention, the curing agent is selected from the group consisting of benzyldimethylamine, triethanolamine, triethylenetetraamine, diethylenetriamine, triethylenamine, dimethylaminoethanol and tri (dimethylaminomethyl) phenol .

In one embodiment of the present invention, the polymer resin and the curing agent may contain a polymer resin to a curing agent in a weight ratio of 6: 1 to 10: 1.

In one embodiment of the present invention, the alumina powder may be prepared by mixing alumina powder having an average particle size of 45 μm and alumina powder having an average particle size of 7 μm at a weight ratio of 6: 4.

In one embodiment of the present invention, the graphite powder and the alumina powder may be mixed with 10 to 30 wt% of graphite powder and 50 to 80 wt% of alumina powder.

The present invention also relates to an alumina powder having an average particle size of 5 to 50 占 퐉 in an acrylic resin or an epoxy resin; And graphite powder; And a step of adding a curing agent and a solvent to the dispersed solution, agitating the mixture, and then curing the mixture.

In one embodiment of the present invention, the epoxy resin is bisphenol A epichlorohydrin epoxy resin, the curing agent is triethylenetetraamine, and the solvent is methyl ethyl ketone (MEK) or toluene (toluene) .

In one embodiment of the present invention, the acrylic resin comprises a polymer or copolymer of methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate and hexyl acrylate Lt; / RTI >

In one embodiment of the present invention, the curing agent is selected from the group consisting of benzyldimethylamine, triethanolamine, triethylenetetraamine, diethylenetriamine, triethylenamine, dimethylaminoethanol and tri (dimethylaminomethyl) phenol .

The present invention also relates to a polymer resin which is an acrylic resin or an epoxy resin; Curing agent; Alumina powder having an average particle size of 5 to 50 mu m; And a graphite powder as an effective component.

The present invention also provides a heat dissipation structure including an adhesive layer formed by applying the composition of the present invention.

In one embodiment of the present invention, the heat dissipation structure may be selected from the group consisting of a heat dissipation plate, a heat dissipation film, a heat dissipation adhesive, a heat dissipation grease, and a heat dissipation tape.

In the present invention, a thermally conductive composite resin composition having improved thermal conductivity is prepared by adding graphite and alumina powder, which are additives having excellent thermal conductivity, to a polymer resin having a low dielectric constant. When the thermally conductive composite resin composition is used for an adhesive, It is possible to induce effective heat radiation by reducing the air gap existing at the interface of the heat dissipation structure and also to reduce the shrinkage rate even after a long period of time and to maintain the shape even under stress so as to be useful for interfacial bonding of the heat dissipation structure. In addition, it is possible to reduce the weight of the composite material composition by 30% or more compared to aluminum, and to have excellent corrosion resistance in a chemical environment and to greatly improve the heat dissipation property, Heat conduction films, heat dissipation structures, and heat conduction adhesives.

Figure 1 shows an FE-SEM image of epoxy resin composite compositions prepared according to one embodiment of the present invention.

The present invention relates to a technique for producing a thermally conductive composite resin composition improved in thermal conductivity by adding graphite and alumina powder to a polymer resin that is an epoxy resin or an acrylic resin, and a method for applying the same to a heat-dissipating material.

Epoxy resins have good metal adhesiveness and development with heat-resistant adhesives is useful. Existing adhesives, despite high initial adhesion to common metals such as aluminum, are somewhat weaker in exposure to moisture and hot environments. In contrast, the epoxy adhesive is environmentally friendly and maintains a constant high adhesive force even at high temperatures. In general, metals are corroded by moisture or air, which also has a considerable influence on heat dissipation properties.

However, adhesives using epoxy resin can reduce not only the effective heat transfer (heat dissipation) but also the corrosion caused by moisture by reducing the air gap existing at the interface between the heating element module and the metal. Epoxy resin can be adhered with high strength even when it is bonded at room temperature. It has a low shrinkage rate even after a long period of time after adhesion between metal and interface, and maintains its shape even under stress.

The present invention relates to a polymer resin which is an acrylic resin or an epoxy resin; Curing agent; An alumina powder having an average particle size of 5 to 50 占 퐉 and graphite powder as an effective component.

In one embodiment of the present invention, the epoxy resin is an epoxy resin having an average of more than two epoxy groups per molecule of one of the resins having two or more epoxy groups in one molecule. Epoxy resins are thermosetting resins that are excellent in electrical insulation, heat resistance and chemical stability.

Preferably, the epoxy resin is selected from the group consisting of bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, cresol novolak epoxy resin, alkylphenol novolac epoxy resin, bisphenol epoxy At least one epoxy compound selected from resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, triglycidyl isocyanates and acyclic epoxy resins can be used, and a bisphenol-A type resin can be most preferably used .

The above epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin may be used in combination with one another such as methyl ethyl ketone (MEK), dimethyl formamide (DMF), methyl cellosolve (MCS), carbitol acetate, carbitol, PGMEA, PGME , Toluene, xylene, NMP, 2-methoxyethanol, etc. may be mixed and dissolved as a solvent.

In one embodiment of the present invention, the acrylic resin may be a polymer or copolymer of methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, and hexyl acrylate .

In the present invention, usable polymeric resin curing agents are not particularly limited, and any curing agent conventionally used in epoxy compositions is not relevant. Preferably, the epoxy resin curing agent which can be used in the production of the epoxy resin composition of the present invention may be an amine type, imidazole type, acid anhydride type or a mixture thereof.

The amine-based curing agents usable in the present invention include linear amines, aliphatic amines, modified aliphatic amines, aromatic amines, secondary amines, and tertiary amines, and examples thereof include benzyldimethylamine, triethanolamine, triethylene Tetramine, diethylenetriamine, triethylenamine, dimethylaminoethanol, and tri (dimethylaminomethyl) phenol.

Examples of the imidazole-based curing agent include imidazole, isomimidazole, 2-methyl imidazole, 2-ethyl-4-methyl imidizole, 2,4-dimethyl imidizole, butyl imidizole, 2-methyldimidazole, 2-undecylidimidizole, 1-vinyl-2-methylimidizole, 2-n-heptadecylimidizole, 2- 2-methylimidizole, 1-propyl-2-methylimidizole, 1-cyanoethyl-2-methyl 1-cyanoethyl-2-ethyl-4-methylimidizole, 1-cyanoethyl-2-undecylimidizole, 1-cyanoethyl- 2-methylimidizole, an adduct of imidazole and methylimidizole, an adduct of imidazole and trimellitic acid, 2-n-heptadecyl-4-methylimidizole, phenylimidazole , Benzylimidizole, 2-methyl-4,5-diphenylimidizole, 2,3,5-triphenylimidizole, 2-styrylimidizole, 1- (dodecylbenzyl) -2- Methyl (2-hydroxy-4-t-butylphenyl) -4,5-diphenylimidazole, 2- (2-methoxyphenyl) (3-hydroxyphenyl) -4,5-diphenylimidazole, 2- (p-dimethyl-aminophenyl) -4,5-diphenylimidazole, 2- Diphenylimidazole, di (4,5-diphenyl-2-imidazole) -benzene-1,4,2-naphthyl-4,5-diphenylimidazole, 1-benzyl- -Methylimidizole and 2-p-methoxystyrylimidazole, and the like.

Examples of the acid anhydride-based curing agent include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl nadic anhydride, nadic anhydride, And an anhydride-based curing agent. The acid anhydride-based curing agent is preferably used by mixing the curing agents as a catalyst, rather than being used alone.

In one embodiment of the present invention, the polymer resin and the curing agent contain a polymer resin and a curing agent in a weight ratio of 8: 1.

Also, in one embodiment of the present invention, when the alumina powder contains more than 90% of the polymer resin, the mechanical properties of the composite composition are significantly deteriorated and the structural stability is weakened. Also, due to the increased specific gravity, it is not effective in reducing the weight of the finished product. Therefore, the alumina powder is preferably contained in an amount of 50 to 90% by weight based on the weight of the polymer resin.

In one embodiment of the present invention, the graphite powder may be natural graphite or artificial graphite alone or a mixture thereof.

 In one embodiment of the present invention, the alumina powder and the graphite powder include 50 to 90% by weight of a mixture of alumina powder and graphite powder based on the total weight of the polymer resin, the curing agent, the alumina powder and the graphite powder , The content ratio of the graphite powder and the alumina powder can be adjusted in the range of 10 to 30: 50 to 80 weight ratio, and the graphite powder and the alumina powder were used in an amount of 30 wt% and 60 wt%, respectively.

The method for producing a thermally conductive composite resin according to the present invention comprises the steps of adding and dispersing graphite powder and alumina powder having an average particle size of 5 to 50 μm in a polymer resin; And adding a curing agent and a solvent to the dispersed solution, agitating the mixture, and curing the mixture.

The polymer resin usable in the present invention is a bisphenol A epichlorohydrin epoxy resin, the curing agent is triethylenetetramine, and the solvent includes but is not limited to methyl ethyl ketone (MEK) and toluene (Toluene) .

The solvent that can be used in the present invention may be selected from the group consisting of methyl ethyl ketone (MEK), toluene, dimethylformamide (DMF), methylcellosolve (MCS), carbitol acetate, carbitol, PGMEA, PGME, toluene , Xylene, NMP, and 2-methoxyethanol. Preferably, MEK / toluene is added in a ratio of 1/1 to 3/1 v / v.

Further, a polymer resin; Curing agent; Alumina powder having an average particle size of 5 to 50 mu m; And graphite powder as an active ingredient can be used as a heat-insulating adhesive composition. When the heat-insulating adhesive composition is used for interfacial bonding of a heat sink, heat transferred to the surface of the heat sink due to a high emissivity of the composition, It can be easily released.

When the heat-radiating adhesive composition is applied to a heat sink, the heat conductive adhesive composition may be applied in a thickness of 10 to 100 탆. The heat conductive composite resin composition or the heat-radiating adhesive composition of the present invention may be used as a heat- Heat-dissipating adhesive, heat-dissipating grease, and heat-insulating tape.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples are only the preferred embodiments of the present invention, and the present invention is not limited by the following Examples.

≪ Example 1 >

Epoxy resin composite material composition manufacturing

≪ 1-1 > Bisphenol A epichlorohydrin Epoxy Preparation of Epoxy Resin Composition Containing Resin and Alumina Powder

10-60wt% alumina powder was dispersed evenly in 8g of Bisphenol A epichlrohydrin (MW ≥700 Struers Epofix) for 24h, and then stirred for 24 hours in a 50 ° C oil bath using a mechanical stirrer.

1 g of triethyltetramine (hardener Struers Epofix) was added to the stirred reaction product and slowly stirred so as not to cause air bubbles. Then, the mixture was cured in a 70 ° C oven for 2 hours to prepare an epoxy composite resin composition in which alumina powder was mixed.

In order to facilitate the dispersion of the SiC filler added to the epoxy resin, the epoxy composite resin composition may be prepared by adding a small amount of a solvent (MEK (methyl ethyl ketone) / Toluene = 1/1 to 3/1 v / v) .

The contents of the alumina powders used for preparing the epoxy composite resin composition in which bisphenol A epichlorohydrin epoxy resin and alumina were mixed as described above are shown in Table 1 below.

[Table 1] Components and contents for preparing bisphenol A epichlorohydrin epoxy resin and alumina powder mixed epoxy resin composition Mix composition of alumina powder for (epoxy + curing agent) = (8 + 1) g>

In the case of the composite resin composition prepared by the above-mentioned method, when the alumina powder is added in a composition of more than 90 wt%, the mechanical properties and adhesion of the composite resin composition are lowered and the structural stability after curing is weakened. Thus, Is contained in a content of 50% or more, the thermal conductivity is 1.0 or more.

≪ 1-2 > Bisphenol A epichlorohydrin Epoxy Manufacture of Epoxy Resin Composition Containing Resin, Graphite Powder and Alumina Powder

The preparation of the epoxy composite resin composition containing bisphenol A epichlorohydrin epoxy resin, alumina powder having an average particle size of 45 탆 and alumina powder having an average particle size of 7 탆 was the same as that of the alumina powder of Example 1-1 Except that alumina powder having an average particle size of 45 탆 and alumina powder having an average particle size of 7 탆 were used, and the powder having an average particle size of 45 탆 and the powder having an average particle size of 7 탆 were respectively 6 : 4 were used as described in Table 2 below.

In order to facilitate the dispersion of the SiC filler added to the epoxy resin, the epoxy composite resin composition may be prepared by adding a small amount of a solvent (MEK (methyl ethyl ketone) / Toluene = 1/1 to 3/1 v / v) .

[Table 2] Components and contents for producing an epoxy composite resin composition in which bisphenol A epichlorohydrin epoxy resin, graphite powder and alumina powder were mixed Graphite powder for (epoxy + curing agent) = (8 + 1) g Mixture of alumina powder and alumina powder>

The surfaces of the above-mentioned production examples were observed through FE-SEM photographing, and the results are shown in Fig.

As a result of the analysis, the use of the mixed filler composition of graphite and alumina shows that the electrical insulation properties of the composition can be improved to a satisfactory level while the thermal conductivity characteristics are greatly improved. When the composition of graphite powder and alumina is 10 (graphite) + It was found that the thermal conductivity was significantly improved when the composition was used in the range of 80 (alumina) wt% ~30 (graphite) +50 (alumina) wt%. Fig. 1 is a photograph showing the surface of the mixed filler composition of graphite and alumina prepared in the present invention.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (14)

A polymer resin which is an acrylic resin or an epoxy resin; Curing agent; Alumina powder having an average particle size of 45 mu m and 7 mu m mixed; And a graphite powder, characterized in that the heat-
The alumina powders having the average particle sizes of 45 탆 and 7 탆 were mixed at a weight ratio of average particle size of 45 탆: average particle size of 7 탆 at a weight ratio of 6: 4,
Wherein the thermally conductive composite resin composition comprises 30% by weight of the graphite powder and 60% by weight of the alumina powder in a total weight of the thermally conductive composite resin composition. The method according to claim 1,
The epoxy resin may be at least one selected from the group consisting of bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, cresol novolak epoxy resin, alkylphenol novolak epoxy resin, bisphenol epoxy resin, An epoxy resin, a dicyclopentadiene type epoxy resin, a triglycidyl isocyanate epoxy resin, and an acyclic epoxy resin. The method according to claim 1,
Wherein the acrylic resin is selected from the group consisting of polymers or copolymers of methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, and hexyl acrylate. Composite resin composition. The method according to claim 1,
Wherein the curing agent is selected from the group consisting of benzyldimethylamine, triethanolamine, triethylenetetraamine, diethylenetriamine, triethylenamine, dimethylaminoethanol and tri (dimethylaminomethyl) phenol. . The method according to claim 1,
Wherein the polymer resin and the curing agent are contained in a weight ratio of the polymer resin to the curing agent in a ratio of 6: 1 to 10: 1. delete delete Alumina powder having an average particle size of 45 탆 and 7 탆 mixed in a polymer resin which is an acrylic resin or an epoxy resin; And graphite powder; And
A method for producing a thermally conductive composite resin composition, which comprises the steps of adding a curing agent and a solvent to a dispersed solution, stirring the mixture, and curing the mixture,
The alumina powders having the average particle sizes of 45 탆 and 7 탆 were mixed at a weight ratio of average particle size of 45 탆: average particle size of 7 탆 at a weight ratio of 6: 4,
Wherein the thermally conductive composite resin composition comprises 30 wt% of the graphite powder and 60 wt% of the alumina powder in a total weight of the thermally conductive composite resin composition. 9. The method of claim 8,
Wherein the epoxy resin is bisphenol A epichlorohydrin epoxy resin, the curing agent is triethylenetetramine, and the solvent is methyl ethyl ketone (MEK) and toluene (Toluene). Gt; 9. The method of claim 8,
Wherein the acrylic resin is selected from the group consisting of polymers or copolymers of methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, and hexyl acrylate. A method for producing a composite resin composition. 9. The method of claim 8,
Wherein the curing agent is selected from the group consisting of benzyldimethylamine, triethanolamine, triethylenetetraamine, diethylenetriamine, triethylenamine, dimethylaminoethanol and tri (dimethylaminomethyl) phenol. ≪ / RTI > A heat-dissipating adhesive composition comprising the thermoconductive composite resin composition of claim 1. A heat dissipation structure comprising an adhesive layer formed by applying the thermoconductive composite resin composition of claim 1. 14. The method of claim 13,
Wherein the heat dissipation structure is selected from the group consisting of a heat dissipation plate, a heat dissipation film, a heat dissipation adhesive, a heat dissipation grease, and a heat dissipation tape.

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