TW202229497A - Thermally conductive adhesive agent composition, adhesive sheet, and production method therefor - Google Patents

Abstract

Provided is a thermally conductive adhesive agent composition containing an adhesive resin and graphene having a two-dimensional structure. The content of the graphene having a two-dimensional structure is preferably 15 to 200 parts by mass, inclusive, relative to 100 parts by mass of the adhesive resin. Furthermore, the glass transition temperature (Tg) of the adhesive resin is preferably -70 to 50 DEG C, inclusive. The thermally conductive adhesive agent composition has excellent thermal conductivity.

Description

Thermally conductive adhesive composition, adhesive sheet and method for producing the same

The present invention relates to a thermally conductive adhesive composition having thermal conductivity, an adhesive sheet, and a method for producing the same.

Conventionally, in electronic devices such as thermoelectric conversion devices, photoelectric conversion devices, semiconductor devices such as large-scale integrated circuits, and the like, heat-dissipating materials having thermal conductivity have been used in order to dissipate heat generated by heat generation. For example, as a method for efficiently dissipating heat generated by an electronic device to the outside, a heat sink having excellent thermal conductivity is provided between the electronic device and a heat sink, or thermal grease is inserted.

Patent Document 1 discloses the above-mentioned heat sink as an example. The heat dissipation sheet of Patent Document 1 is produced by applying and drying a coating liquid of a heat dissipation material containing an adhesive resin, an inorganic filler, a curing agent, and a solvent on a release sheet, a base material, and the like. As the above-mentioned inorganic fillers, plate-shaped inorganic particles formed of aluminum, silver, copper, boron nitride, graphite, etc., and spherical inorganic particles formed of silica, alumina, graphite, and the like are disclosed.

In addition, Patent Document 2 discloses the above-mentioned heat-dissipating grease as an example. In the heat-dissipating grease of Patent Document 2, aluminum, boron nitride, graphite, magnesium oxide, aluminum oxide, and aluminum nitride are used as the blended thermally conductive filler. [Prior Technology Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2015-67713. Patent Document 2: Japanese Patent Laid-Open No. 2016-162929.

[Problems to be Solved by Invention]

However, conventional heat sinks have not always obtained the desired thermal conductivity. In order to obtain high thermal conductivity, if the conventional heat sink is filled with inorganic fillers, the surface roughness becomes large, it becomes difficult to generate tack, and there are disadvantages such as failure to obtain the adhesiveness when adhering to the adherend. In addition, when the inorganic filler is highly filled, the flexibility of the heat sink is lowered, and the electronic device, the heat sink, etc. cannot be sufficiently followed and adhered, and the thermal conductivity between members may be lowered.

On the other hand, in the conventional heat-dissipating grease, there is a drive that accompanies the electronic device. The temperature rise caused by the stop. Cooling and repeated expansion and contraction, the problem of a pump out phenomenon of oil leakage occurs. Therefore, it is desired that the heat-dissipating material disposed between the electronic device and the heat sink, in addition to having flexibility. In addition to followability, it also has adhesive properties that are not easy to leak.

The present invention was made in view of such a situation, and an object thereof is to provide a thermally conductive adhesive composition excellent in thermal conductivity and adhesiveness, an adhesive sheet, and a method for producing the same. [means to solve the problem]

In order to achieve the above object, first, the present invention provides a thermally conductive adhesive composition comprising an adhesive resin and graphene having a two-dimensional structure (Invention 1).

Graphene has a two-dimensional structure, and in this structure, the graphenes are easily brought into contact with each other, and a thermal conduction path for heat transfer in the thermally conductive adhesive composition is easily formed. In addition, graphene having a two-dimensional structure is characterized by a very high thermal conductivity in a plane. Therefore, the thermally conductive adhesive composition of the above invention (Invention 1) is excellent in thermal conductivity even if the content of graphene having a two-dimensional structure is small. In addition, the thermally conductive adhesive composition of the above invention (Invention 1) contains an adhesive resin, and its blending ratio can be increased, thereby exhibiting good adhesive properties and flexibility. Followability.

In the above invention (Invention 1), the content of the graphene having a two-dimensional structure is preferably 15 parts by mass or more and 200 parts by mass or less relative to 100 parts by mass of the adhesive resin (Invention 2).

In the above inventions (Inventions 1 and 2), the glass transition temperature (Tg) of the adhesive resin is preferably -70°C or higher and 50°C or lower (Invention 3).

Second, the present invention provides an adhesive sheet comprising at least an adhesive layer, wherein the adhesive layer is composed of the thermally conductive adhesive composition (Inventions 1 to 3) (Invention 4) .

In the above invention (Invention 4), the adhesive force to stainless steel polished 600 times is preferably 0.1 N/25 mm or more (Invention 5).

In the above inventions (Inventions 4 and 5), the thermal conductivity of the adhesive layer is 5W/m. K or more is preferred (Invention 6).

In the above inventions (Inventions 4 to 6), in the absorption spectrum of the adhesive layer obtained by Raman measurement, the absorption intensity peak (ID ) in the _D -band near the wavenumber of 1250cm ⁻¹ is relative to the wavenumber of 1570cm ⁻ The ratio (D/G) of the absorption intensity peak (I _G ) in the G-band near ¹ is preferably 0.5 or less (Invention 7).

Third, the present invention provides a method for producing an adhesive sheet, which is the method for producing the above-mentioned adhesive sheet (Inventions 4 to 7), characterized by comprising: a step of preparing a coating liquid of the thermally conductive adhesive composition; The step of forming an adhesive layer by applying and drying the coating liquid of the thermally conductive adhesive composition, and the step of preparing the coating liquid includes: a first step of containing a part of the total amount of the prepared adhesive resin. , The mixture of the graphene and the solvent with the two-dimensional structure is subjected to dispersion treatment to obtain a preliminary mixture; in the second step, at least the remaining aforementioned adhesive resin is added to the aforementioned preliminary mixture, and a dispersion treatment is applied, relative to the aforementioned For 100 parts by mass of graphene having a two-dimensional structure, the amount of the adhesive resin mixed in the first step is 0.5 parts by mass or more and 50 parts by mass or less (Invention 8). [Inventive effect]

The thermally conductive adhesive composition and the adhesive sheet of the present invention have excellent thermal conductivity and adhesiveness. Moreover, according to the manufacturing method of the adhesive sheet of this invention, the adhesive sheet excellent in thermal conductivity and adhesiveness can be manufactured.

[Form for carrying out the invention]

Hereinafter, embodiments of the present invention will be described. [Thermal Conductive Adhesive Composition] A thermally conductive adhesive composition according to an embodiment of the present invention includes an adhesive resin and graphene having a two-dimensional structure. The thermally conductive adhesive composition of the present embodiment is excellent in thermal conductivity and adhesiveness by having the above-mentioned configuration.

Since the graphene having a two-dimensional structure of the present embodiment has a two-dimensionally extending planar structure, the graphenes are easily brought into contact with each other, and a thermal conduction path (path) for heat transfer is easily formed in the thermally conductive adhesive composition. In addition, graphene with two-dimensional structure has 3000W/m in the plane direction. Very high thermal conductivity around K. Furthermore, compared with conventional inorganic fillers such as metals, metal oxides, and nitrides, graphene has a low specific gravity of about 2.25 and is characterized by being difficult to settle. Therefore, even if the content of graphene having the above-mentioned two-dimensional structure is small (for example, even 10% by volume), the thermally conductive adhesive composition of the present embodiment is excellent in thermal conductivity. Specifically, 5.0W/m can be exerted. Very good conductivity above K.

In addition, since the thermally conductive adhesive composition of the present embodiment contains an adhesive resin, there is no risk of oil and fat leaking due to a pumping phenomenon, and good adhesive performance can be maintained. Further, since a large amount of graphene does not need to be blended as described above, the blending ratio of the adhesive resin can be relatively increased. Thereby, the thermally conductive adhesive composition of the present embodiment can fully exhibit the adhesiveness and flexibility of the adhesive resin. performance such as followability. That is, the thermally conductive adhesive composition of the present embodiment is not only excellent in adhesiveness, but also in flexibility. Followability is also excellent. Regarding adhesiveness, specifically, excellent adhesive force of 0.1N/25mm or more can be exhibited. Therefore, it is possible to sufficiently follow and adhere to a heat source such as an electronic device, and a heat dissipation member such as a heat sink, and to exhibit excellent thermal conductivity even during use.

Here, the thermal conductivity of 20-36W/m is used in the past. The thermal conductivity of K alumina, or the plane direction is 200W/m. In the heat sink of inorganic fillers such as boron nitride of about K, in order to exhibit 5.0W/m. For thermal conductivity of K or more, based on Bruggeman's formula, it is necessary to add at least 50 vol% or more of inorganic fillers. However, in this case, since the packing ratio of the inorganic filler is close to the closest packing (about 70% by volume), there is a limit to exhibiting high thermal conductivity as described above. In addition, the heat sink added with an inorganic filler of more than 50% by volume significantly reduces flexibility, adhesion, etc., and cannot be followed. The heat source and heat-dissipating member are attached, and the thermal conductivity is impaired. In addition, carbon fibers (carbon nanotubes, carbon nanofibers) are known as materials with high thermal conductivity. However, since carbon fibers have a highly cylindrical structure with a high aspect ratio, the entanglement of carbon fibers increases the viscosity of the mixture. Significantly, it is difficult to add a blending amount sufficient to increase the thermal conductivity.

1. Each component (1) Adhesive resin The type of the adhesive resin in the thermally conductive adhesive composition of the present embodiment is not particularly limited, and for example, any of acrylic, polyester, urethane, rubber, silicone, and the like may be used. In addition, the adhesive can be any one of emulsion type, solvent type or solvent-free type, and can also be any one of cross-linked type or non-cross-linked type. Furthermore, it may be active energy ray non-curable or active energy ray sclerosing.

The glass transition temperature (Tg) of the adhesive resin of the present embodiment is preferably -70°C or higher, more preferably -60°C or higher, particularly preferably -50°C or higher, and further preferably -40°C or higher. Further, the glass transition temperature (Tg) is preferably 50°C or lower, more preferably 40°C or lower, particularly preferably 25°C or lower, and further preferably 15°C or lower. When the glass transition temperature (Tg) is within the above range, the dispersibility of the graphene having a two-dimensional structure in the thermally conductive adhesive composition is improved, and the flexibility and adhesiveness are improved. In addition, the glass transition temperature (Tg) of the adhesive resin in this specification is a value calculated based on the FOX formula.

As an acrylic adhesive resin, the (meth)acrylate polymer which polymerized (meth)acrylate monomer etc. is mentioned preferably. In addition, in this specification, (meth)acrylate means both acrylate and methacrylate. The same applies to other similar terms. In addition, "polymer" also includes the concept of "copolymer".

The (meth)acrylate polymer as an adhesive resin preferably contains an alkyl (meth)acrylate as a monomer unit constituting the polymer. Thereby, the obtained thermally conductive adhesive composition can exhibit favorable adhesiveness. Alkyl groups may be linear, branched or cyclic.

As the alkyl (meth)acrylate, an alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms is preferable from the viewpoint of adhesiveness. Examples of alkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylate. n-butyl meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, (meth)acrylate n-decyl acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearate (meth)acrylate, and the like.

Among the above, from the viewpoint of imparting good adhesiveness and the dispersibility of graphene having a two-dimensional structure, alkyl (meth)acrylate having an alkyl group having 1 to 9 carbon atoms is more preferable. Among them, alkyl (meth)acrylates having an alkyl group of 1 to 6 carbon atoms are particularly preferred, and alkyl (meth)acrylates having an alkyl group of 1 to 4 carbon atoms are further preferred. Specifically, methyl (meth)acrylate can be preferably mentioned, and methyl acrylate is particularly preferred. These may be used alone or in combination of two or more.

From the viewpoint of imparting good adhesiveness and the dispersibility of graphene having a two-dimensional structure, the (meth)acrylate polymer as the monomer unit constituting the polymer contains alkyl (meth)acrylate The base ester is preferably 20 mass % or more, more preferably contains 30 mass % or more of alkyl (meth)acrylate, particularly preferably contains 35 mass % or more of alkyl (meth)acrylate, and contains (methyl) ) 40 mass % or more of alkyl acrylate is more preferable. In addition, from the viewpoint of securing the content of other monomers (for example, reactive functional group-containing monomers described later), it is preferable to contain 99.9 mass % or less of alkyl (meth)acrylate, and to contain (methyl) ) 95 mass % or less of alkyl acrylate is more preferable, 90 mass % or less of alkyl (meth)acrylate is especially preferable, and 85 mass % or less of alkyl (meth)acrylate is more preferable.

The (meth)acrylate polymer used as the adhesive resin preferably contains a reactive functional group-containing monomer having a reactive functional group in the molecule as a monomer constituting the polymer. By including the reactive functional group-containing monomer, the dispersibility of graphene having a two-dimensional structure can be further improved according to its polarity. Moreover, when the thermally conductive adhesive composition of this embodiment contains a crosslinking agent, the reactive functional group derived from this reactive functional group containing monomer becomes a crosslinking point, and can form a crosslinking structure.

Preferred examples of the reactive functional group-containing monomer include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomer), monomers having a carboxyl group in the molecule (carboxyl group-containing monomer), and monomers having an amine group in the molecule. (amine group-containing monomer), etc. Among these, from the viewpoint of the dispersibility of graphene having a two-dimensional structure, a hydroxyl group-containing monomer is preferable. These may be used alone or in combination of two or more.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. -Hydroxyalkyl (meth)acrylate such as hydroxybutyl, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among them, 2-hydroxyethyl (meth)acrylate is preferred, and 2-hydroxyethyl acrylate is particularly preferred, from the viewpoint of dispersibility of graphene having a two-dimensional structure. These may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

As an amino group-containing monomer, aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. are mentioned, for example. These may be used alone or in combination of two or more.

As a monomer constituting this polymer, the (meth)acrylate polymer contains the lower limit of the reactive functional group-containing monomer, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and The content of 1 mass % or more is particularly preferred, and the content of 5 mass % or more is further preferred. In addition, as a monomer unit constituting this polymer, the (meth)acrylate polymer (A) contains the upper limit of the reactive functional group-containing monomer, preferably 30% by mass or less, and preferably 25% by mass The content is more preferably less than or equal to 20% by mass, particularly preferably 20% by mass or less, and even more preferably 15% by mass or less. When the (meth)acrylate polymer contains a reactive functional group-containing monomer in the above range as a monomer unit constituting the polymer, the dispersibility of graphene having a two-dimensional structure becomes better.

The (meth)acrylate polymer as an adhesive resin may further contain other monomers as monomers constituting the polymer. As this other monomer, for example, alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; acrylamide, Non-crosslinkable acrylamide such as methacrylamide; N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylic acid Non-crosslinkable (meth)acrylates having tertiary amine groups such as esters; vinyl acetate; styrene and the like. These may be used alone or in combination of two or more.

The polymerization aspect of the (meth)acrylate polymer may be a random (random) polymer or a block polymer.

The weight average molecular weight of the (meth)acrylate polymer is preferably at least 10,000, more preferably at least 20,000, particularly preferably at least 50,000, and further preferably at least 100,000. In addition, the above-mentioned weight average molecular weight is preferably 2 million or less, more preferably 1.5 million or less, particularly preferably 1.2 million or less, and even more preferably 1 million or less. When the weight average molecular weight is in the above-mentioned range, the dispersibility of the graphene having a two-dimensional structure in the thermally conductive adhesive composition becomes favorable, and the flexibility and adhesiveness become more favorable. In addition, in this specification, the weight average molecular weight is a value in terms of standard styrene measured by gel permeation chromatography (GPC).

Moreover, the thermally conductive adhesive composition of this embodiment may contain 1 type of said (meth)acrylate polymer, or may contain 2 or more types of said (meth)acrylate polymer. In addition, the thermally conductive adhesive composition of this embodiment may contain another (meth)acrylate polymer in addition to the above-mentioned (meth)acrylate polymer.

As the adhesive resin in the thermally conductive adhesive composition of the present embodiment, a rubber-based adhesive resin can be used. As rubber-based adhesive resins, for example, polyisobutylene-based resins, polybutylene-based resins, isoprene-isobutylene copolymers, styrene-isoprene-styrene block copolymers, Styrene-butadiene-styrene block copolymer, styrene-butadiene rubber copolymer, natural rubber, modified natural rubber, etc.

The content of the adhesive resin in the thermally conductive adhesive composition is preferably 30% by mass or more, preferably 35% by mass, based on the total solid content (that is, when the total solid content excluding the solvent is 100 parts by mass) The above is more preferable, 40 mass % or more is particularly preferable, and 50 mass % or more is further preferable. Moreover, the said content is preferably 90 mass % or less, more preferably 85 mass % or less, and particularly preferably 80 mass % or less. When the content of the adhesive resin is within the above range, the dispersibility of graphene having a two-dimensional structure in the thermally conductive adhesive composition becomes more favorable, and the flexibility and adhesiveness become more favorable.

(2) Graphene with two-dimensional structure The thermally conductive adhesive composition of the present embodiment contains graphene having a two-dimensional structure. Graphene is a two-dimensional compound with a two-dimensional structure in which carbon atoms are regularly arranged in a hexagonal shape, and is initially formed from a single layer of atoms. In this specification, "graphene having a two-dimensional structure" may be a plurality of layers, and the thickness is preferably 1/10 of the shortest length in a plan view shape. In addition, in this specification, graphene includes thinly exfoliating (splitting) graphite (cleaved) to be generated. In this specification, graphite itself does not correspond to the aforementioned "graphene having a two-dimensional structure".

As described above, graphene having a two-dimensional structure may be a single layer or a plurality of layers. In the case of a plurality of layers, it is usually about 2 to 1000 layers. The planar shape of the graphene having a two-dimensional structure is not particularly limited.

The graphene having a two-dimensional structure of the present embodiment is preferably a graphene having a two-dimensional crystal structure from the viewpoint of more excellent thermal conductivity. Here, "graphene having a two-dimensional crystal structure" means that it has structural periodicity in the two-dimensional direction, and has a layer formed by the thickness of a single atom, and is formed only by this layer, or this layer is formed by ordinary There are about 2 to hundreds of layers of Dewali. In this "graphene having a two-dimensional crystal structure", experimentally, in wide-angle X-ray diffraction (WAXD), a clear crystal peak can be obtained from its periodic structure. In addition, even in the case of a plurality of layers, crystal peaks belonging to the periodic structure in the thickness direction of the layers can be obtained.

When measuring the thermally conductive adhesive composition containing graphene having a two-dimensional crystal structure (the adhesive layer composed of the same) by X-ray diffraction using a CuKα radiation source (wavelength: 0.15418 nm), at 2θ It is better to detect the peaks at the positions of 26.6° and 42.4°. The above-mentioned 2θ is the diffraction peaks at 26.6° and 42.4°, which are the interlayer and in-plane crystalline peaks of graphene. By detecting the peaks at such positions, it can be said that the graphene has a crystalline structure.

The method for producing graphene having a two-dimensional structure is not particularly limited, but for example, a method of physically cleaving graphite, or a method of cleaving primary oxidized graphite to form a single layer (graphene oxide), This reduction method (reduced graphene oxide (RGO)) and the like. Among them, graphene obtained by a method of physically cleaving graphite is preferable from the viewpoint of better thermal conductivity by having a favorable two-dimensional crystal structure.

The average particle size of the graphene having a two-dimensional structure is preferably 0.5 μm or more, more preferably 1.0 μm or more, particularly preferably 3.0 μm or more, and even more preferably 5.0 μm or more. As a result, since the graphenes are easily brought into contact with each other and a thermal conduction path is easily formed, the feature of the two-dimensional structure has an effect, and the thermally conductive adhesive composition is more excellent in thermal conductivity. In addition, the average particle size of the graphene having a two-dimensional structure is preferably 30 μm or less, particularly preferably 20 μm or less, and further preferably 15 μm or less. Thereby, the dispersion state in the solvent, adhesive resin, etc., and other materials can be maintained, and the formation of a thermal conduction path due to segregation can be suppressed, and the thermal conductivity can be improved.

In addition, the thickness of the graphene having a two-dimensional structure is preferably 500 nm or less, more preferably 300 nm or less, particularly preferably 200 nm or less, and further preferably 100 nm or less. Thereby, the flexibility of the thermally conductive adhesive composition (adhesive layer composed of the thermally conductive adhesive composition) can be well maintained. On the other hand, the lower limit of the thickness of graphene having a two-dimensional structure is not particularly limited, but is usually preferably 0.7 nm or more, more preferably 5.0 nm or more, and 10 nm or more from the viewpoint of thermal conductivity It is particularly preferred, and 15 nm or more is further preferred.

Relative to 100 parts by mass of the adhesive resin, the content of graphene having a two-dimensional structure is preferably 15 parts by mass or more, more preferably 17 parts by mass or more, particularly preferably 18.5 parts by mass or more, and more than 20 parts by mass for better. By setting the lower limit of the content of the graphenes as described above, the graphenes are easily brought into contact with each other, and heat conduction paths are easily formed, so that the graphenes are more excellent in thermal conductivity.

In addition, with respect to 100 parts by mass of the adhesive resin, the content of graphene having a two-dimensional structure is preferably 200 parts by mass or less, more preferably 170 parts by mass or less, particularly preferably 150 parts by mass or less, and 130 parts by mass Parts or less are further preferred. In the present embodiment, by using graphene having a two-dimensional structure, as described above, even if the content is small, desired thermal conductivity can be obtained. Further, by relatively increasing the content of the adhesive resin, flexibility and adhesiveness become more excellent.

The content of graphene having a two-dimensional structure in the thermally conductive adhesive composition is preferably more than 5% by volume, more preferably more than 7% by volume, more preferably more than 8% by volume, and further more preferably more than 9% by volume good. In addition, the content of the above-mentioned graphene is preferably 50 vol % or less, more preferably 40 vol % or less, particularly preferably 35 vol % or less, and further preferably 15 vol % or more. When the content of the above graphene is in the above range, the thermal conductivity becomes more excellent. In addition, by relatively increasing the content of the adhesive resin, flexibility and adhesiveness become more excellent.

(2) Various additives The thermally conductive adhesive composition of the present embodiment may contain, if necessary, a crosslinking agent, an ultraviolet absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softener, a filler, a refractive index adjuster, Rust inhibitor, flame retardant, etc. The thermally conductive adhesive composition of the present embodiment may contain conventional thermally conductive fillers such as aluminum, boron nitride, graphite, magnesium oxide, aluminum oxide, and aluminum nitride, in addition to graphene having a two-dimensional structure. The thermally conductive adhesive composition of the present embodiment preferably does not contain conventional thermally conductive fillers other than graphene having a two-dimensional structure. In addition, the additive which comprises a thermally conductive adhesive composition does not contain the solvent mentioned later.

The thermally conductive adhesive composition of the present embodiment may contain a thermosetting component such as an epoxy resin as needed, but the content of the thermosetting component in the thermally conductive adhesive composition in this case is less than 5 The mass % is preferable, 3 mass % or less is more preferable, and 1 mass % or less is particularly preferable. Moreover, it is preferable that the thermally conductive adhesive composition of this embodiment does not contain a thermosetting component.

2. Preparation of coating liquid of thermally conductive adhesive composition Conventionally used inorganic fillers such as metals, metal oxides, and nitrogen compounds have a high specific gravity compared to adhesive resins, solvent components, and the like, and have a problem of being prone to sedimentation in the composition. Therefore, in order to control the distribution and sedimentation of inorganic fillers, it is necessary to adjust the viscosity of coating liquid components, modify the inorganic fillers, and add dispersants on the material side. coating equipment, etc. On the other hand, the graphene having a two-dimensional structure used in this embodiment has a specific gravity as low as 2.25, and is characterized by being difficult to settle due to uniform dispersion. Therefore, no modification treatment, dispersing agent, etc. are required, and it can be Handles in a wide viscosity range.

The coating liquid of the thermally conductive adhesive composition of the present embodiment can be prepared according to a conventional method, but the preparation method of the coating liquid of the thermally conductive adhesive composition of the present embodiment preferably includes the following steps: The first step is to apply a dispersion treatment to a mixture containing a part of the total amount of the blended adhesive resin, graphene having a two-dimensional structure, and a solvent to obtain a preparatory mixture; the second step, at least the remaining adhesive The resin is added to the above-mentioned preliminary mixture, a solvent is added, and a dispersion treatment is performed. Thereby, a coating liquid of a thermally conductive adhesive composition in which graphene having a two-dimensional structure is uniformly dispersed can be obtained.

2-1. The first step In the first step of the present embodiment, a mixture containing a part of the total amount of the blended adhesive resin, graphene having a two-dimensional structure, a solvent, a cross-linking agent, additives and the like as needed is prepared, and the mixture is dispersed deal with. Thereby, the above-mentioned aggregation of graphene can be suppressed by performing the dispersion treatment in a state with a relatively high viscosity. As a result, the graphene in the mixture can be uniformly dispersed.

With respect to 100 parts by mass of graphene having a two-dimensional structure, the upper limit of the mixing amount of the adhesive resin in the first step is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and 25 parts by mass or less. Excellent. As a result, by performing the dispersion treatment in a state with a relatively high viscosity, the graphene having a two-dimensional structure can be more easily dispersed uniformly. In addition, with respect to 100 parts by mass of graphene having a two-dimensional structure, the lower limit of the mixing amount of the adhesive resin in the first step is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and 2 parts by mass or more. Parts or more are particularly preferred, and 3 parts by mass or more is further preferred.

The dispersion treatment of the above-mentioned mixture can be carried out by a conventionally known method, for example, a known kneader, dispersion machine such as a homogenizer, a bead mill, a ball mill, a jet mill, a disperser, a mixer, a kneader, an ultrasonic disperser, or the like. machine. For the dispersion treatment, a single apparatus can be used, or two or more kinds of apparatuses can be used in combination.

Among the above, by excessively pulverizing graphene, it is suppressed to significantly reduce the thermal conductivity, and from the viewpoint of uniformly dispersing the above-mentioned graphene in the mixture while suppressing the aggregation of graphene, a disperser, mixer, jet mill or It is better to disperse by ultrasonic disperser. When the dispersion treatment of the above mixture is performed using a disperser, the disperser is preferably stirred for 10 minutes or more at a rotation number of 500 to 5000 rpm, and more preferably performed at a rotation number of 1000 to 4000 rpm and stirred for 20 minutes or more.

The solvent used for the preparation of the coating liquid of the thermally conductive adhesive composition is not particularly limited. For example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, and aromatic hydrocarbons such as toluene and xylene can be used. , halogenated hydrocarbons such as dichloromethane and dichloroethane, alcohols such as methanol, ethanol, propanol, butanol, 1-methoxy-2-propanol, acetone, methyl ethyl ketone, 2-pentanone, isophor Ketones such as ketones and cyclohexanone, esters such as ethyl acetate and butyl acetate, cellosolve-based solvents such as ethyl cellosolve, N,N-dimethylformamide, trimethyl-2- Pyrrolidone, butyl carbitol, etc., but preferably methyl ethyl ketone.

With respect to 100 parts by mass of graphene having a two-dimensional structure, the upper limit of the mixing amount of the solvent in the first step is preferably 10,000 parts by mass or less, particularly preferably 5,000 parts by mass or less, and more preferably 2,000 parts by mass or less. good. Thereby, the dispersion treatment can be performed in a state with a high viscosity, and it is easier to uniformly disperse the graphene having a two-dimensional structure. In addition, with respect to 100 parts by mass of graphene having a two-dimensional structure, the lower limit of the mixing amount of the adhesive resin in the first step is preferably 200 parts by mass or more, more preferably 500 parts by mass or more, and 800 parts by mass or more. Parts or more are particularly preferred, and 1000 parts by mass or more is further preferred.

2-2. Second step In the second step of the present embodiment, the remaining adhesive resin is added to the preliminary mixture obtained in the first step, and a dispersion treatment is performed. In this second step, it is preferable to add a solvent. The type of solvent and the conditions of the dispersion treatment are the same as those in the first step.

The amount of the solvent added in the second step is not particularly limited as long as the viscosity of the coating liquid of the thermally conductive adhesive composition obtained can be within a coatingable range, and can be appropriately selected according to the situation. Usually, the solid content concentration of the thermally conductive adhesive composition is preferably 2 to 50 mass %, particularly preferably 5 to 40 mass %, and more preferably 10 to 35 mass %.

Through the above steps, a coating liquid of the thermally conductive adhesive composition in which graphene having a two-dimensional structure is uniformly dispersed can be obtained. By applying the coating liquid of the thermally conductive adhesive composition, an adhesive layer in which graphene having a two-dimensional structure is uniformly dispersed can be formed.

[adhesive sheet] The adhesive sheet of the present embodiment includes at least an adhesive layer, wherein the adhesive layer is composed of the thermally conductive adhesive composition of the aforementioned embodiment.

The specific structure which is an example of the adhesive sheet of this embodiment is shown in FIG. 1. FIG. As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 of one embodiment is composed of two release sheets 12a, 12b, and the two release sheets 12a, 12b sandwiched so as to be in contact with the release surfaces of the two release sheets. The adhesive layer 11 of 12b is constituted. In addition, the peeling surface of a peeling sheet in this specification means the surface which has peeling property of a peeling sheet, and includes both a surface to which a peeling process is given and a surface which shows peelability even if it does not give a peeling process.

1. Each part 1-1. Adhesive layer The adhesive layer 11 of the present embodiment is composed of the thermally conductive adhesive composition of the aforementioned embodiment.

1-2. Peeling sheet The release sheets 12a and 12b protect the adhesive layer 11 before using the adhesive sheet 1, and are peeled off when the adhesive sheet 1 (the adhesive layer 11) is used. In the pressure-sensitive adhesive sheet 1 of the present embodiment, one or both of the release sheets 12a and 12b are not always necessary.

As the release sheets 12a and 12b, for example, polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polybutylene films, etc. can be used. Ethylene phthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene. (Meth) acrylic copolymer film, ethylene. (Meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. In addition, these crosslinked films can also be used. Furthermore, these laminated films may be used.

The peeling surfaces of the peeling sheets 12a and 12b (particularly the surfaces in contact with the adhesive layer 11) are preferably subjected to peeling treatment. As a release agent used for a peeling process, the release agent of an alkyd type, a silicone type, a fluorine type, an unsaturated polyester type, a polyolefin type, and a wax type is mentioned, for example. In addition, among the peeling sheets 12a and 12b, one peeling sheet may be a heavy peeling type peeling sheet having a large peeling force, and the other peeling sheet may be a light peeling type peeling sheet having a small peeling force.

The thickness of the release sheets 12a and 12b is not particularly limited, but is usually about 20 to 150 μm.

2. Manufacture of adhesive sheet As an example of manufacture of the adhesive sheet 1, the coating liquid of a thermally conductive adhesive composition is apply|coated to the peeling surface of one peeling sheet 12a (or 12b). Next, the coating film is dried (heated), and this coating film is superimposed on the peeling surface of the other peeling sheet 12b (or 12a). When the aging period is required, the above-mentioned coating film becomes the adhesive layer 11 as it is by setting the aging time, and when the aging period is not required. Thereby, the said adhesive sheet 1 can be obtained.

As a method of applying the coating liquid of the thermally conductive adhesive composition, for example, a bar coating method, a blade coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method can be used. Wait.

By drying (heating) the coating liquid of the thermally conductive adhesive composition, the solvent is volatilized to form an adhesive layer. The drying conditions are preferably 0.5-30 minutes at 90-150°C, and particularly preferably 1-10 minutes at 100-120°C.

In addition, when the thermally conductive adhesive composition contains a crosslinking agent, it is usually crosslinked by heat treatment (which may be the above-mentioned drying treatment). After the heat treatment, if necessary, an aging period of about 1 to 2 weeks may be provided at normal temperature (for example, 23° C., 50% RH).

Here, carbon fibers such as carbon nanotubes and carbon nanofibers, which are typical heat dissipation materials in the past, have anisotropy in the long-axis direction (one-dimensional) of the fibers. In order to exhibit thermal conductivity, other particulate fillers need to be used together. To control the orientation, a strong magnetic field generator is used to make the orientation of the carbon fibers consistent. On the other hand, although the graphene used in this embodiment is an anisotropic material, since it has a two-dimensionally expanded planar structure, the graphenes are easily in contact with each other, and even without special orientation treatment, the obtained The adhesive layer 11 exhibits excellent thermal conductivity.

3. Physical properties, etc. (1) Thickness of the adhesive layer The thickness of the adhesive layer 11 (value measured in accordance with JIS K7130) is preferably 2 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more as a lower limit value from the viewpoint of adhesiveness. More preferably, it is 20 μm or more.

The upper limit of the thickness of the adhesive layer 11 is preferably 500 μm or less, more preferably 300 μm or less, particularly preferably 100 μm or less, and even more preferably 50 μm or less, from the viewpoint of thermal conductivity.

Here, regarding conventional carbon fibers such as carbon nanotubes and carbon nanofibers, a space in which the carbon fibers can move freely is required when performing the above-described alignment treatment. Therefore, when carbon fibers are oriented in the film thickness direction of the heat sink, it is necessary to secure a film thickness equal to or greater than the length of the filler, and the film thickness is generally designed to be 0.5 to 2.0 mm. In addition, in the method of manufacturing a heat sink after performing an orientation treatment, since cutting is performed by a slicer such as a cutter or a laser, the slicer has to have a thickness of 1 mm or more for stable production in the mechanism of the slicer.

On the other hand, in the case of graphene having a two-dimensional structure, since the above-mentioned special orientation treatment is not required, the adhesive layer 11 of the present embodiment can be formed into a film with a very thin thickness as described above. The build-up layer is easy to thicken. That is, in the present embodiment, the thickness of the adhesive layer 11 can be easily controlled.

(2) Thermal conductivity The thermal conductivity of the adhesive layer 11 is 5W/m. K or above is better, with 5.5W/m. K or above is better, with 6.0W/m. K and above are particularly preferred. Thereby, the adhesive sheet 1 can have excellent thermal conductivity. In particular, in the conventional inorganic fillers such as carbon black, alumina, boron nitride, etc., even if the addition amount is large, it is difficult to achieve 5W/m. High thermal conductivity of K. However, the adhesive sheet 1 of the present embodiment can achieve such high thermal conductivity by using graphene having a two-dimensional structure. In addition, the measuring method of thermal conductivity in this specification is shown in the test example mentioned later.

(3) Adhesion The adhesive force of the adhesive sheet 1 of the present embodiment to stainless steel polished 600 times is preferably 0.1N/25mm or more, more preferably 0.15N/25mm or more, and particularly preferably 0.2N/25mm or more. The adhesive sheet 1 of the present embodiment can exhibit excellent thermal conductivity even if the content of graphene having a two-dimensional structure is small, so the content of the adhesive resin in the adhesive layer 11 can be relatively large, and excellent adhesive force can be exhibited .

On the other hand, the upper limit of the adhesive force is not particularly limited, but is usually preferably 50N/25mm or less, more preferably 15N/25mm or less, and particularly preferably 5N/25mm or less. In addition, the measuring method of the adhesive force of this specification is shown in the test example mentioned later.

(4) Raman Peak Intensity Ratio D/G Regarding the adhesive layer 11 of the present embodiment, in the absorption spectrum obtained by Raman measurement, the absorption intensity peak (ID ) in the _D -band near the wavenumber of 1250 cm ⁻¹ is relative to The ratio (D/G) of the absorption intensity peak (I _G ) in the G-band near the wavenumber of 1570 cm ^-1 (hereinafter, also referred to as "Raman peak intensity ratio D/G") is preferably 0.5 or less, preferably 0.4 or less. More preferably, 0.3 or less is particularly preferred, and 0.2 or less is further preferred. If the above-mentioned Raman peak intensity ratio D/G is as described above, it can be understood that graphene having a two-dimensional structure includes a favorable crystal structure. Thereby, the adhesive sheet 1 exhibits more excellent thermal conductivity due to the graphene having a two-dimensional structure. The lower limit of the Raman peak intensity ratio D/G is not particularly limited, but is usually preferably 0.001 or more.

In addition, the specific method of the Raman measurement of this specification is shown in the test example mentioned later. In addition, the peak in the G-band near the wave number 1570 cm ^-1 is the peak that shows the peak in the region of ±100 cm ^-1 centered on the wave number 1570 cm ^-1 , and the absorption intensity peak ( _IG ) is shown as borrowed The relative value of the absorption intensity of the peak top obtained by the measurement. Similarly, the peak of the _D -band near the wave number 1250 cm ^-1 is the peak that shows the peak in the region of ±100 cm ^-1 centered on the wave number 1250 cm ^-1 , and the absorption intensity peak (ID ) is shown by the measurement. The relative value of the absorption intensity at the peak top.

[radiation device] As shown in FIG. 2 , a heat dissipating device 3 according to an embodiment of the present invention includes a heat generating member 31 , a heat transfer member 32 , and an adhesive layer 11 provided between the heat generating member 31 and the heat transfer member 32 .

The adhesive layer 11 of the present embodiment is preferably composed of the thermally conductive adhesive composition of the foregoing embodiment, or the adhesive layer 11 of the adhesive sheet 1 of the foregoing embodiment. The heat generating member 31 and the heat transfer member 32 are bonded together via the adhesive layer 11 . The adhesive layer 11 has excellent thermal conductivity because it contains graphene having a two-dimensional structure, and also follows and adheres to the heat generating member 31 and the heat transfer member 32 flexibly. Therefore, the heat generated by the heat generating member 31 is efficiently thermally conducted to the heat transfer member 32 through the adhesive layer 11 , and the heat is efficiently dissipated to the outside by the heat transfer member 32 .

Although the heat generating member 31 of the present embodiment generates heat as it performs a predetermined function, it is required to be a member that suppresses temperature rise, or a member that controls the flow of heat generated by the member to a specific direction. Examples of such heat generating members 31 include thermoelectric conversion devices, photoelectric conversion devices, semiconductor devices such as large-scale integrated circuits, LED light-emitting elements, optical pickups, electronic devices such as power transistors, portable terminals, Various electronic devices such as wearable terminals, batteries, batteries, motors, engines, and the like.

The heat transfer member 32 of the present embodiment is a member that radiates the received heat, or a member that transfers the received heat to another member, or the like. Such a heat transfer member 32 is a material with high thermal conductivity, and is preferably formed of, for example, metals such as aluminum, stainless steel, and copper, graphite, carbon nanofibers, or the like. The form of the heat transfer member 32 may be any of a substrate, a housing, a heat sink, a heat sink, and the like, and is not particularly limited.

The exothermic device 3 is manufactured, for example, by peeling off one release sheet 12 a (or 12 b ) from the adhesive sheet 1 , and sticking one surface of the exposed adhesive layer 11 to the heat generating member 31 . Next, the other peeling sheet 12 b (or 12 a ) is peeled off from the adhesive layer 11 provided on the heat generating member 31 , and the other surface of the exposed adhesive layer 11 is attached to the heat transfer member 32 . In addition, after one surface of the adhesive layer 11 is attached to the heat transfer member 32 , the heat generating member 31 may be attached to the other surface of the adhesive layer 11 .

The above-described embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-described embodiment is intended to include all design changes, equivalents, and the like that belong to the technical scope of the present invention.

For example, in FIG. 1, the release sheet 12a or the release sheet 12b of the adhesive sheet lamination may be omitted.

In addition, the adhesive sheet of the present invention may be laminated in the following order: a desired base material, the adhesive layer 11, and the release sheet 12a (or 12b). The material constituting the base material is not particularly limited, and examples thereof include resin films, nonwoven fabrics, paper, graphite sheets, graphene sheets, and metal base materials, and resin films are generally used. As the resin material constituting the resin film, polyester, polyolefin, nylon 6, nylon 66, polyamide such as partially aromatic polyamide, polyimide, polyamideimide, polyether ether ketone and the like can be used , polyether, polyphenylene sulfide, polycarbonate, polyurethane, ethylene-vinyl acetate copolymer, polytetrafluoroethylene and other fluororesins, acrylic resins, polyacrylates, polystyrene, polyvinyl chloride, polyvinylidene Resins such as vinyl chloride. The above-mentioned resin film may be formed using a single resin material containing such resins, or may be formed using a mixture of two or more resin materials. The above-mentioned resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

Further, the shapes of the heat generating member 31 and the heat transfer member 32 of the thermal device 3 are not limited to those shown in FIG. 2 , and may be various shapes. [Example]

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1] 5 parts by mass of an acrylate polymer as an adhesive resin (5 parts by mass in a total of 100 parts by mass; solid content concentration), and graphene having a two-dimensional structure (manufactured by ADEKA, product name "CNS-1A1") 25 parts by mass (solid content concentration) and 325 parts by mass of methyl ethyl ketone as a solvent were mixed, and a dispersing process was performed using a disperser (manufactured by Primix, product name "Robomix") by stirring at 3000 rpm for 30 minutes to prepare a preliminary mixture (No. one step). In addition, the details of the above-mentioned acrylate polymer and graphene having a two-dimensional structure are as follows. . Acrylate polymer: a copolymer obtained by copolymerizing 85 parts by mass of methyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate, weight average molecular weight: 300,000, glass transition temperature (Tg): 6°C. . Graphene with two-dimensional structure: manufactured by ADELA, product name "CNS-1A1", two-dimensional crystal structure, average particle size of 12 μm, thickness of 50 nm or less, Raman peak intensity ratio D/G=0.1, surrounded by X-rays In the radiation method, when measuring using a CuKα radiation source (wavelength: 0.15418 nm), peaks were detected at the positions of 26.6° and 42.4° in 2θ.

To the above-mentioned preliminary mixture, 95 parts by mass of the same acrylate mixture as described above (95 parts by mass in 100 parts by mass of the total; solid content concentration) and 175 parts by mass of methyl ethyl ketone as a solvent were added, and a disperser (Primix Co., Ltd., product Named "Robomix"), by stirring at 3000 rpm for 30 minutes, the dispersion treatment (second step) was performed to obtain a coating liquid of the thermally conductive adhesive composition. The solid content concentration of the coating liquid of this thermally conductive adhesive composition was 20 mass %.

The obtained coating liquid of the thermally conductive adhesive composition was applied to the peeling-treated surface with an applicator, heat-treated at 100° C. for 2 minutes, and then dried to form an adhesive layer, wherein the adhesive layer was formed. The peeling-treated surface was a peeling-treated surface of a peeling film (manufactured by Lintec, product name "SP-PET3811(S)") in which one side of the polyethylene terephthalate film was peeled off with a silicone-based peeling agent. Then, the peeling-treated side of the polyethylene terephthalate film (product name "SP-PET381031") of the polyethylene terephthalate film whose one side was peeled off with a silicone-based peeling agent was bonded to the adhesive layer. , to make an adhesive sheet (release film/adhesive layer/release film) with an adhesive layer thickness of 30 μm.

[Examples 2 to 3] In the first step, the mixing amount of the acrylate polymer, the graphene with a two-dimensional structure, and the blending amount of the solvent, and the blending amount of the acrylate polymer and the solvent in the second step are as shown in Table 1. Except having changed, it carried out similarly to Example 1, and produced the adhesive sheet.

[Example 4] 5 parts by mass of a polyisobutylene-based resin as an adhesive resin (5 parts by mass in a total of 100 parts by mass; solid content concentration), and a hydrogenated petroleum resin as a tackifier (manufactured by Arakawa Chemical Industry Co., Ltd., product name "Arcon P -125") 2.5 parts by mass, graphene with a two-dimensional structure (manufactured by ADEKA, product name "CNS-1A1") 2.5 parts by mass (solid content concentration), and 245 parts by mass of toluene as a solvent were mixed, using a disperser ( The product made by Primix Co., Ltd., product name "Robomix") was subjected to dispersion treatment by stirring at 3000 rpm for 30 minutes to prepare a preliminary mixture (first step).

To the above-mentioned preliminary mixture, 95 parts by mass of the same polyisobutylene-based resin as described above (95 parts by mass in 100 parts by mass of the total; solid content concentration), and hydrogenated petroleum resin (manufactured by Arakawa Chemical Industry Co., Ltd.) as a tackifier were added. Product name "Arcon P-125") 47.5 parts by mass, and 132 parts by mass of toluene as a solvent, using a disperser (manufactured by Primix, product name "Robomix"), by stirring at 3000 rpm for 30 minutes, a dispersion treatment ( The second step), a coating liquid of the thermally conductive adhesive composition is obtained. Using the obtained coating liquid of the thermally conductive adhesive composition, an adhesive sheet was produced in the same manner as in Example 1.

[Comparative Example 1] 100 parts by mass (solid content concentration) of the same acrylate polymer as in Example 1 as an adhesive resin, 43 parts by mass of carbon black (manufactured by Mitsubishi Chemical Corporation, product name "#3030B"), and 330 parts by mass of methyl ethyl ketone as a solvent Mixing was performed using a disperser (manufactured by Primix, product name "Robomix") by stirring at 3000 rpm for 30 minutes, and dispersion treatment was performed to prepare a coating liquid of the thermally conductive adhesive composition. Using the obtained coating liquid of the thermally conductive adhesive composition, an adhesive sheet was produced in the same manner as in Example 1.

[Comparative Example 2] 100 parts by mass (solid content concentration) of the same acrylate polymer as in Example 1 as the adhesive resin, 195 parts by mass (solid content) of alumina (manufactured by Showa Denko, product name "CB-P10", average particle size 8 μm) concentration) and 690 parts by mass of methyl ethyl ketone as a solvent, mixed with a disperser (manufactured by Primix, product name "Robomix"), and subjected to dispersion treatment by stirring at 3000 rpm for 30 minutes to prepare a coating liquid of the thermally conductive adhesive composition . Using the obtained coating liquid of the thermally conductive adhesive composition, an adhesive sheet was produced in the same manner as in Example 1.

[Comparative Example 3] 100 parts by mass (solid content concentration) of the same acrylate polymer as in Example 1 as the adhesive resin, 43 parts by mass (solid content concentration) of boron nitride (manufactured by Showa Denko, product name "UHP2", average particle size 11 μm) ) and 330 parts by mass of methyl ethyl ketone as a solvent, and using a disperser (manufactured by Primix, product name "Robomix"), a dispersion treatment was performed by stirring at 3000 rpm for 30 minutes to prepare a coating liquid of the thermally conductive adhesive composition. Using the obtained coating liquid of the thermally conductive adhesive composition, an adhesive sheet was produced in the same manner as in Example 1.

[Test Example 1] <Measurement of thermal conductivity> From the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples, a square sample of 5 mm on each side was obtained. Use thermal diffusivity. A thermal conductivity measuring device (manufactured by ai-phase, product name "ai-phase mobile") was used to measure the thermal conductivity of the above-mentioned sample (adhesive layer) in accordance with ISO 22007-3 in an environment of 23°C and 50% RH. rate (W/m.K). The results are shown in Table 1.

[Test example 2] <Measurement of adhesive force> The coating liquids of the thermally conductive adhesive compositions prepared in Examples and Comparative Examples were applied to a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmo Shine PET50A4100", film thickness 50 μm) after that, it was heat-treated at 100° C. for 2 minutes and dried to prepare an adhesive sheet (PET film/adhesive layer) with an adhesive layer thickness of 30 μm.

The obtained adhesive sheet was cut into a short booklet with a width of 25 mm and a length of 250 mm, and the adhesive layer of the adhesive sheet was attached to the grinding surface of a stainless steel (SUS) plate that was ground 600 times, and was removed by a 2 kg rubber roller back and forth once. pressed. After standing at 23°C and 50% RH for 24 hours, the adhesive sheet was peeled off from the SUS plate using a tensile tester (Orientec, Tencilon) under the conditions of a peeling speed of 300 mm/min and a peeling angle of 180 degrees. Adhesion was measured. Here, the conditions other than those described are measured in accordance with JIS Z0237:2009. The results are shown in Table 1.

[Test example 3] <Evaluation of filler dispersibility> The coating liquids of the thermally conductive adhesive compositions prepared in the examples and comparative examples were put into a sample bottle (capacity 70 mL) and left to stand, and the fillers (graphene, carbon black, alumina and boron nitride) dispersion state. Then, the dispersibility of the filler was evaluated by the following criteria. The results are shown in Table 1. ○: The filler is not precipitated, and the dispersion is uniform. Δ: Part of the filler settles. ╳: Most of the filler settles.

[Test Example 4] <Raman Measurement> Raman measurement was performed on the adhesive layer of the adhesive sheet produced in the Example using a microlaser Raman spectrometer (manufactured by Thermo Fisher, product name "DXR2"). Then, the graph obtained by measuring the absorption spectrum at a laser wavelength of 532 nm is obtained from the absorption intensity peak (I _G ) in the G band near the wave number 1570 cm ^-1 and the absorption intensity peak (ID ) in the _D band near the wave number 1250 cm ^-1 , The ratio of the absorption intensity peak (I _G ) to the absorption intensity peak (ID ) (Raman peak intensity ratio _D /G) was calculated. The results are shown in Table 1. In addition, in this Raman measurement, information about the graphene itself contained in the adhesive layer can be obtained, regardless of the difference in the amount of graphene added.

[Table 1] The first step (preparing the mixture) second step all Thermal conductivity (W/m.K) Adhesion (N/25mm) Filler Dispersibility Raman peak intensity ratio D/G adhesive resin filler Solvent (parts by mass) Adhesive resin (parts by mass) Solvent (parts by mass) filler type parts by mass type parts by mass volume% Example 1 Acrylate polymer 5 Graphene 25 325 95 175 11.6 5.1 0.18 ○ 0.08 Example 2 Acrylate polymer 7 Graphene 33 360 93 170 14.9 6.9 0.27 ○ 0.08 Example 3 Acrylate polymer 10 Graphene 100 630 90 170 34.4 5.8 0.27 ○ 0.08 Example 4 Polyisobutylene resin 5 Graphene 25 245 95 132 9.1 5.5 1.59 ○ 0.08 Comparative Example 1 Acrylate polymer 100 carbon black 43 330 18.4 0.9 0.02 ○ Comparative Example 2 Acrylate polymer 100 Alumina 195 690 36.8 3.3 0.03 ╳ Comparative Example 3 Acrylate polymer 100 Boron Nitride 43 330 36.0 3.0 0.05 △

It can be understood from Table 1 that the adhesive sheets produced in the examples have excellent thermal conductivity and adhesive force. In addition, the thermally conductive adhesive composition (the coating liquid) prepared in the examples has excellent dispersibility of the two-dimensionally structured graphene.

[industrial availability] The thermally conductive adhesive composition and adhesive sheet of the present invention are suitable, for example, to be inserted between a heat-generating electronic device and a heat-dissipating substrate or a heater to cool the electronic device.

1: adhesive sheet 11: Adhesive layer 12a, 12b: release sheet 3: heat dissipation device 31: Heating parts 32: Heat transfer parts

FIG. 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a heat dissipating device according to an embodiment of the present invention.

1: adhesive sheet

11: Adhesive layer

12a, 12b: release sheet

Claims (8)

A thermally conductive adhesive composition, characterized in that it contains: adhesive resin, and Graphene with a two-dimensional structure. The thermally conductive adhesive composition according to claim 1, wherein the content of the graphene having a two-dimensional structure relative to 100 parts by mass of the adhesive resin is 15 parts by mass or more and 200 parts by mass or less. The thermally conductive adhesive composition according to claim 1, wherein the glass transition temperature (Tg) of the adhesive resin is -70°C or higher and 50°C or lower. An adhesive sheet comprising at least an adhesive layer, wherein the adhesive layer is composed of the thermally conductive adhesive composition according to any one of Claims 1 to 3. The adhesive sheet according to claim 4, wherein the adhesive force with respect to stainless steel polished 600 times is 0.1 N/25mm or more. The adhesive sheet according to claim 4, wherein the thermal conductivity of the aforementioned adhesive layer is 5W/m. above K. The adhesive sheet according to claim 4, wherein in the absorption spectrum of the adhesive layer obtained by Raman measurement, the absorption intensity peak (ID ) in the _D -band near the wavenumber of 1250 cm ⁻¹ is relative to the wave number of 1570 cm The ratio (D/G) of the absorption intensity peak (I _G ) in the G-band near ^-1 is 0.5 or less. A manufacturing method of an adhesive sheet, which is the manufacturing method of the adhesive sheet as claimed in claim 4, characterized in that it has: The step of preparing the coating liquid of the aforementioned thermally conductive adhesive composition; The step of forming an adhesive layer by coating and drying the coating liquid of the thermally conductive adhesive composition, The steps of preparing the aforementioned coating solution include: The first step is to apply a dispersion treatment to the mixture containing a part of the total amount of the prepared adhesive resin, the graphene with a two-dimensional structure, and the solvent to obtain a preliminary mixture; In the second step, at least the remaining aforementioned adhesive resin is added to the aforementioned preparatory mixture and subjected to dispersion treatment, The mixing amount of the adhesive resin in the first step is 0.5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the graphene having the two-dimensional structure.

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