KR102493729B1 - Adhesive sheets for heat dissipation - Google Patents

Abstract

The present application relates to a heat dissipation adhesive sheet comprising: a heat dissipation layer; at least one or more metal thin film layers formed on a lower surface of the heat dissipation layer; and an adhesive layer formed on a lower surface of the metal thin film layer. The heat dissipation adhesive sheet of the present application, by enabling to be easily cut into various sizes and attached closely even on a substrate with an out-of-plane curve, has an effect of simply and conveniently cooling a substrate part requiring heat dissipation.

Description

Heat dissipation adhesive sheet {ADHESIVE SHEETS FOR HEAT DISSIPATION}

The present application relates to a heat radiation sheet, and more particularly, to a sheet having a function of lowering the temperature of a surface of a heating element or a high-temperature substrate by attaching to various heating elements and a high-temperature substrate.

Heat control of electronic products and parts has been an issue for a long time. Electrical and electronic devices such as semiconductor chips, chargers, and LEDs all generate heat during operation. This is because when electricity flows through a wire, a certain portion of the electrical energy is changed into heat and light by resistance. Heat generation means a reduction in the efficiency and performance of electronic components as well as a reduction in product life.

In modern electronic products, various parts, including semiconductors, are refined, miniaturized, and highly integrated, causing local heat generation to become more severe, and various heat dissipation control materials and solutions are being developed to prevent this.

Among the heat control and cooling materials, among the heat dissipation elements in the form of sheets or thin films that are easy to use, there is a graphite sheet that quickly spreads concentrated heat from a specific area to a wide area to lower the temperature, a vapor chamber that spreads and dissipates high heat from the SoC, and a heat sink. Demand for such as etc. is increasing, and there is a heat-dissipating coating agent or heat-dissipating paint that can lower the temperature by coating regardless of the shape of the heating material.

However, the graphite sheet requires a separate adhesive coating for close contact with the heating element, and compared to the high thermal conductivity in the transverse direction, the low thermal conductivity in the vertical direction and the poor adhesion between graphite particles cause problems such as breaking the film or scattering powder. there is On the other hand, in the case of a vapor chamber or a metal heat sink, they have a certain weight and volume and are not flexible, so they are relatively limited to applications such as flat panel displays or PC boards.

In addition, heat-dissipating paints or coatings may be suitable for producing standardized mass products, but there is an inconvenience in precisely heat-dissipating a small area or various parts in a small amount. That is, it is difficult to meet the various needs of end consumers.

In addition to electric and electronic products and parts, high-performance heat dissipation material technology is increasingly needed for various air conditioning parts, batteries, fuel cells, and other materials that require cooling.

Therefore, there is a demand for the development of a heat dissipation material that has excellent heat dissipation performance and can lower the temperature of the heating part by attaching various sizes (areas) and shapes to various substrates.

Korean Patent Registration No. 10-1550083 (Announced on September 3, 2015)

The problem to be solved by the present application is to provide a heat dissipating adhesive sheet that can achieve a desired goal by being easily attached to various substrates requiring a temperature reduction by heat dissipation.

One embodiment of the present application is a heat dissipation layer; At least one metal thin film layer formed on the lower surface of the heat dissipation layer; and an adhesive layer formed on the lower surface of the metal thin film layer.

In one embodiment of the present application, the heat dissipation layer contains 70 to 85 wt % of a binder resin, 12 to 25 wt % of thermally conductive particles, and 3 to 10 wt % of an additive based on the total weight of the composition forming the heat dissipation layer. The binder resin is a urethane or epoxy resin, and the thermally conductive particles include at least one or more graphite selected from the group consisting of expanded graphite, impression graphite, artificial graphite, and earthy graphite; and metal particles; can include

In one embodiment of the present application, the metal thin film layer is made of aluminum (Al), copper (Cu), gold (Au), silver (Ag), nickel (Ni), tin (Sn), zinc (Zn), and It includes at least one selected from the group consisting of alloys, and the thickness of the metal thin film layer may be 10 to 1,000 ㎛, preferably 20 to 300 ㎛.

In one embodiment of the present application, the adhesive layer may include at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive, and may have a thickness of 5 to 50 μm.

In one embodiment of the present application, the adhesive layer is selected from the group consisting of graphite, carbon black, alumina, aluminum nitride (AlN), boron nitride (BN), graphene, graphite powder, and carbon nanotubes (CNT). It may include at least one thermally conductive particle.

In one embodiment of the present application, the sheet may further include a release layer on the lower surface of the adhesive layer.

In one embodiment of the present application, the heat dissipation layer is formed of a one-component composition or a two-component composition, and the thickness of the heat dissipation layer may be 10 to 100 μm.

In one embodiment of the present application, the two-component composition is mixed by adding a diisocyanate-based curing agent or an amine-based curing agent to a main composition containing a binder resin that is a urethane resin, and calcined at 70 ° C to 100 ° C to form a heat dissipation layer can form

In one embodiment of the present application, in the one-component composition, the main component of the binder resin is polyol, and 6 to 15% by weight of block diisocyanate is further included to form a composition, and the composition is calcined at 120 ° C to 180 ° C to form a heat dissipation layer. can form

In one embodiment of the present application, the graphite is milled for 2 to 6 hours to pulverize and exfoliate graphene nanoplates (GNP) and graphene from graphite to separate a certain amount, and the graphene nanoplate The particle diameter of the plate may be 0.1 to 50 μm. In the composition after milling, two or more of graphite particles, graphene nanoplates, and graphene may be mixed, or both may be mixed.

In one embodiment of the present application, the milling bead used in the milling may be zirconia having a diameter of 0.05 to 3.0 mm.

In one embodiment of the present application, the composition may further include 0.5 to 1.5% by weight of a nonionic surfactant based on the total weight of the composition.

In one embodiment of the present application, the acetate-based solvent is N-butyl acetate, acetate, ethyl acetate, amyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol methyl acetate, diethylene glycol ethyl It may be at least one selected from the group consisting of acetate, ethylene glycol monoethyl ether acetate, 3-methoxybutyl acetate, and propylene glycol methyl ether acetate (PGMEA).

In one embodiment of the present application, the metal particles are at least one selected from the group consisting of aluminum, copper, zinc, tin, nickel, magnesium, chromium, and zirconium, and flakes having a diameter of 5 to 40 μm. can be of type

One embodiment of the present application provides an article on which the heat dissipating adhesive sheet is formed.

The heat dissipation adhesive sheet of the present application has the advantage of being usable for a wide variety of substrates that require heat dissipation, such as semiconductor chips, PCB substrates, electronic devices, electronic product cases, batteries and battery cases, chargers, wireless chargers, and LED lights.

Existing heat dissipation parts solve the problem that it was not easy to provide appropriate heat dissipation performance by attaching them to substrates of various sizes and shapes, and they can be easily cut into various sizes and adhered closely to substrates with out-of-plane curves. It has the advantage of being able to cool the substrate part requiring heat dissipation conveniently.

1 shows the structure of a heat dissipating adhesive sheet according to an embodiment of the present application.
2 shows the structure of a heat dissipating adhesive sheet according to an embodiment of the present application.
3 relates to a method for measuring heat dissipation performance of a heat dissipation adhesive sheet according to an embodiment of the present application.
4 shows the measurement results of heat dissipation efficiency according to milling time.
5 shows the results of measuring the vertical thermal conductivity according to the milling time.
6 shows the results of measuring the horizontal thermal conductivity according to the milling time.
7 is an SEM picture of expanded graphite.
8 is a SEM picture after milling expanded graphite for 3 hours.
9 is a TEM photograph after milling expanded graphite for 3 hours.

Advantages and features of the present application, and how to achieve them, will become clear with reference to the embodiments described below in detail. However, the present application is not limited to the embodiments disclosed below and may be implemented in various different forms, but only the present embodiments make the disclosure of the present application complete, and common knowledge in the art to which this application belongs. It is provided to fully inform the person who has the scope of the application, and this application is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning commonly understood by those of ordinary skill in the art to which this application belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined.

Terminology used herein is for describing the embodiments and is not intended to limit the present application. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used herein, "comprises" and/or "comprising" does not exclude the presence or addition of one or more other elements other than the recited elements.

In this specification, the numerical range represented by "-" means "above" and "below". For example, notation with 2 to 15 mm means 2 mm or more and 15 mm or less.

1 shows the structure of a heat radiation adhesive sheet. Referring to Figure 1, one side of the metal thin film layer 20 of a certain thickness is the adhesive layer 30, the other side is three layers consisting of the heat dissipation layer 10, or when the heat dissipation layer is made of two layers, the entire It is a multi-layer sheet composed of 4 layers.

The metal thin film layer is made of aluminum (Al), gold (Au), silver (Ag), nickel (Ni), tin (Sn), zinc (Zn), tungsten (W), iron (Fe), and alloys thereof. may include one or more selected from the group consisting of

The metal thin film layer 20 may be selected in various thicknesses from about 20 to 1,000 μm. If the metal thin film is too thin, the sheet may be ruptured or distorted during the coating process of the heat dissipation layer and the adhesive layer, and the consumer may be inconvenient to be crumpled or ruptured while using the product. Also, if the aluminum thin film is too thin, the rate at which heat from the hot spot spreads along the aluminum thin film may not be sufficient. On the other hand, if the aluminum thin film is too thick, it is not easy to attach to substrates of various shapes and it is not easy to coat the heat dissipation layer in a roll-to-roll manner. Therefore, the thickness of the metal thin film layer is suitably 20 ~ 1,000 ㎛, particularly preferably 20 ~ 500 ㎛. If the metal thin film having a thickness within this range is used, the heat dissipation adhesive sheet can be easily manufactured in a roll-to-roll method, and the shape of the heat dissipation adhesive sheet can be easily changed from the consumer's point of view to adhere to various types of substrates.

In the present invention, the adhesive layer may include at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive, and may have a thickness of 5 to 50 μm, more preferably 10 to 30 μm.

In the adhesive layer, at least one thermally conductive particle selected from the group consisting of graphite, carbon black, alumina, aluminum nitride (AlN), boron nitride (BN), graphene, and carbon nanotube (CNT) is dispersed to conduct heat of the adhesive layer. degree can be improved. Alumina is suitable for spherical shapes of 10 μm or less, and graphite powder is suitable for crushed graphite, earthy graphite, or expanded graphite powder with a size of 0.1 to 10 μm. This is because interlayer exfoliation proceeds simultaneously through the crushing of expanded graphite, so that a certain amount of graphene or GNP (graphene nanoplate) having excellent thermal conductivity can be produced at the same content. The content of alumina or expanded graphite powder is suitable for 10 to 50%, preferably 20 to 30%. If the content of the thermally conductive particles is too high, the adhesive strength of the adhesive layer is lowered, and if the content is too low, the thermal conductivity of the adhesive layer is low and the thermal insulation phenomenon of the adhesive layer is increased.

2 shows the structure of a heat radiation adhesive sheet.

Referring to FIG. 2 , the adhesive sheet may further include a release layer 40 on the lower surface of the adhesive layer 30 . The release layer 40 can be easily removed to attach to a target substrate.

1 and 2, the heat dissipation layer 10 is formed of a one-component composition or a two-component composition, and may have a thickness of 10 to 100 μm.

The two-component composition may be mixed by adding a diisocyanate-based curing agent or an amine-based curing agent to a main composition containing a binder resin that is a urethane resin or an epoxy resin, respectively, and calcined at 70 ° C to 100 ° C to form a heat dissipation layer. . A heat dissipation layer can be formed by curing for 20 to 30 minutes.

The two-part composition includes 20 to 35% by weight of a binder resin; 5 to 15% by weight of thermally conductive particles; 3 to 10% by weight of additives; And it may be a mixture of a main agent containing 10 to 60% by weight of an acetate-based solvent and 15 to 30% by weight of an isocyanate curing agent.

As a component constituting the urethane resin, the polyol is acrylic polyol, caprolactone polyol, epoxy polyol, ester polyol, ether polyol, polycarbonate polyol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene glycol, diethylene glycol , 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl- 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8- It may be at least one selected from the group consisting of decanediol, octanedecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol. More specifically, it may be an acrylic polyol, a caprolactone polyol, an ester polyol, or a mixture thereof.

Even in the case of a polyfunctional polyol, any polymer having a hydroxyl group capable of forming a main chain of a polyurethane compound may be used without limitation. Due to the polyol component, excellent reworkability characteristics such as residue reduction can be expressed.

Considering the use of heat sinks and heat sinks for electronic products such as displays, it has excellent adhesion to metal interfaces and has excellent hardness and thermal shock resistance to match the characteristics of heat dissipation parts that undergo repeated temperature rise and cooling depending on whether or not electronic products are used. A polyol was selected to Polyester polyol, which is widely used in polyurethane production, exhibits a disadvantage in that adhesion to a metal interface is poor when used alone, and as a result, it is weak against thermal shock. Therefore, when considering interfacial adhesion, impact resistance, hardness, and curing characteristics, a three-component polyol may be used by mixing acrylic polyol and polyester polyol or adding caprolactone polyol to further improve adhesion and impact resistance. The type and mixing ratio of resin can be variously selected in consideration of strength, hardness, and heat resistance (Tg) according to the requirements of the properties of the coating film.

The isocyanate-based curing agent is preferably a polyfunctional aliphatic isocyanate compound. When an aromatic isocyanate compound or an alicyclic isocyanate compound is used, it hardens within 1 hour, so sufficient time for heat dissipation coating is not secured, resulting in poor coating productivity. Since the aliphatic isocyanate compound has low reactivity, it does not harden for more than 6 hours, so the usability of the paint is improved. In addition, there is an advantage that the curing temperature can be fired within 15 minutes to 1 hour or 20 minutes to 40 minutes at a curing temperature of 70 ℃ to 100 ℃, 75 ℃ to 90 ℃. In the case of a heat-dissipating paint composition used for electronic parts, it is preferable that the firing temperature of the heat-dissipating paint is within 100 degrees Celsius because problems may occur in electronic parts when the firing temperature exceeds 100 °C.

The isocyanate-based curing agent is, specifically, hexamethylene diisocyanate (HDI), HDI trimer, trimethylene diisocyanate, tetramethylene diisocyanate, 1,2-propylene Diisocyanate (1,2- propylene diisocyanate), 1,3-butylene diisocyanate (1,3- butylene diisocyanate), dodecamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate ( 2,4,4-trimethylhexamethylene diisocyanate) may be at least one selected from the group consisting of, but is not limited thereto.

The ratio of the main agent and the curing agent is determined by the OH value and the NCO value, and it is preferable to set the ratio with an NCO equivalent of about 10% higher than the OH equivalent. This is because NCO can react with moisture and participate in the curing reaction by forming a dimer or the like, while an excess polyol cannot participate in the curing reaction and may remain as a so-called dangling chain.

The composition includes ethylene glycol, propylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1, 3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl A spacer selected from the group consisting of -1,8-octanediol, 1,8-decanediol, octanedecanediol, glycerin, trimethylolpropane, pentaerythritol, and hexanetriol may be used. It is possible to control the length of the urethane chain and the crosslink density after curing by using a spacer.

The composition may use a curing catalyst that is dibutyl tin dilaurate.

The epoxy resin is not particularly limited as long as it exhibits curing and adhesive action, but an epoxy resin having two or more functional groups is preferred as a solid or close-to-solid epoxy.

As the epoxy resin, bisphenol-based epoxy, novolac (Cresol novolac)-based epoxy, and amine-based epoxy may be exemplified.

An amine-based curing agent may be used as a curing agent for the epoxy resin. Examples thereof include hexamethylenediamine, triethyldiamine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isoformdiamine, diethylenetriamine, triethylenetetramine, diethyl It may be at least one or more selected from the group consisting of aminopropylamine (diethylamino propyl amine).

The mixing ratio of epoxy resin to curing agent is 1:1 by calculating the epoxy equivalent and the amine equivalent.

One-component urethane is a state in which the main agent and the curing agent are mixed in advance. That is, when a blocked isocyanate in which an isocyanate group is blocked is added to the above-described subject and mixed, a one-component urethane binder is obtained. Blocked isocyanates are available in HDI-based products and are also commercially available. The one-component urethane binder using block diisocyanate is not reactive below a certain temperature, and the blocking unit or protection unit is thermally decomposed above a certain temperature, exposing the hidden isocyanate and starting the reaction. One-component urethane is excellent in storage because it does not cure to a certain temperature, and it is easy to control the reaction speed when mixing the main agent and hardener, so it is easier to work than the two-component type, which is not easy to control the coating work time, so it is advantageous in productivity. do. However, most block groups are decomposed at 120 ° C or higher, so it cannot be used when a film forming (curing) reaction at a lower temperature is required.

The one-component composition includes 25 to 45% by weight of a polyol; 7 to 20% by weight of thermally conductive particles; 5 to 10% by weight of additives; 6 to 15% by weight of block isocyanate; And 10 to 50% by weight of an acetate-based solvent; a one-component urethane heat-dissipating paint composition comprising a heat-dissipating layer may be formed by curing at 120 ° C to 180 ° C for 10 to 60 minutes.

The polyol is acrylic polyol, caprolactone polyol, epoxy polyol, ester polyol, ether polyol, polycarbonate polyol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene glycol, diethylene glycol, 1,3-butanediol, 1 ,4-butanediol, neopentylglycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1 ,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octanedecanediol, glycerin , It may be at least one selected from the group consisting of trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol. More specifically, it may be an acrylic polyol, a caprolactone polyol, a polyester polyol, or a mixture thereof.

The block isocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI, isophorone diisocyanate), tetramethylene diisocyanate, pentamethylene diisocyanate, toluene diisocyanate (TDI , toluene diisocyanate), butane diisocyanate, pentane diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (HMDI, dicyclohexylmethane-4,4'-diisocyanate), 4,4'-methylenebis(phenyl isocyanate)], norbornene diisocyanate, hydrogenated xylendi At least one or more selected from the group consisting of isocyanate (hydrogenated xylene diisocyanate), hydrogenated diphenylmethane diisocyanate, 1,4-cyclohexane diisocyanate, or a trimer thereof; Selected from the group consisting of dimethyl pyrazole (DMP, 3,5-dimethyl pyrazole), dimethyl malonate (DEM), methyl ethyl ketone oxime (MEKO), and caprolactam (ε-CAP) The block isocyanate is thermally decomposed at 120 to 180 ° C., and the isocyanate group is It reacts with polyol to form urethane polymer chains.

The blocked isocyanate resin may be included in an amount of 25 to 40% by weight based on 100% by weight of the total coating composition. If too little or too much is added, the crosslinking density decreases and the strength of the coating film weakens.

The selection of block isocyanate depends on the curing temperature and time, so it can be selected according to the application and the conditions of film formation. In general, deblocking is performed at a temperature of about 120 to 150 ° C, but when ε-CAP is used as a blocking agent, a relatively high temperature of 160 ° C or more is required.

The composition may use a curing catalyst that is dibutyl tin dilaurate. Urethane resin causes a curing reaction between polyol and diisocyanate at a relatively low temperature and at a sufficiently fast rate. If speed reduction is required, the use of a catalyst helps to reduce the overall reaction rate.

Since the heat dissipation layer formed of the one-component heat dissipation paint composition has a working time of 120 hours or more, there is no limitation in the process of preparing the paint before coating and the actual working time.

In the heat dissipation layer, the thermally conductive particles may include at least one graphite selected from the group consisting of expanded graphite, impression graphite, artificial graphite, and earthy graphite.

It is known that the expanded graphite is exfoliated into graphene nanoplates (GNPs) or graphene through various processes such as milling, ultra-high pressure dispersion, and ultrasonic waves. GNP refers to a state composed of hundreds of graphene layers by exfoliation between graphene layers constituting graphite. Expanded graphite is easily separated between layers when an external force is applied due to the widening of the space between the graphene layers of the graphite, and as a result, a certain portion of graphene and GNP are generated. In the present invention, the expanded graphite is pre-exfoliated using an ultra-high pressure disperser or ultrasonic waves, and then mixed with polyol constituting the binder and other particles and additives, and treated in a mixing-milling process to prepare a heat-dissipating paint, and separate pre-treatment and exfoliation It was confirmed that peeling could occur only with a milling process after mixing with other components such as a binder without a process. In the milling process, the milling speed and the size of zirconia (ZrO _{2 )} used as milling beads affect exfoliation. The diameter of zirconia is preferably 0.2 to 3.0 mm. Further, the diameter of zirconia is more preferably 0.5 to 2.0 mm. In the case of milling beads having a size of 0.5 to 2.0 mm, the graphite exfoliation effect is excellent even after milling for 2 to 5 hours.

In one embodiment of the present application, the graphite is exfoliated by wet milling for 2 hours to 6 hours, more specifically for 2 hours to 5 hours, and the diameter of the graphite particles after the grinding and exfoliation is 0.1 to 50 can be μm. In the present invention, it was confirmed that expanded graphite having a diameter of 3 to 100 μm was crushed and exfoliated to 0.1 to 50 μm after milling for 2 to 4 hours.

Compared to expanded graphite, natural graphite such as impression graphite and earth graphite can shorten the milling time, and even if sufficient milling time is maintained, delamination of graphite does not occur easily, so the heat dissipation efficiency does not change significantly depending on the milling time. However, compared to expanded graphite, natural graphite has advantages in that it is easy to control the viscosity of paint and has excellent productivity.

In one embodiment of the present application, the composition may be mixed by adding a block isocyanate-based curing agent after the milling.

In one embodiment of the present application, the expanded graphite may be graphite in which interlayer expansion is performed by heat treatment after acid treatment.

The heat-dissipating paint composition may have a viscosity between 300 cps and 2,000 cps at 25°C. When the viscosity is within the above range, it may be more advantageous in terms of the sedimentation rate of the thermally conductive particles and the stability of the dispersion process. If it is less than 300 cps, it may be difficult to create a heat dissipation coating film due to dripping of the composition, and even after creation, the adhesive strength with the coated surface may be weakened, and if it exceeds 2,000 cps, the coating process may not be easy, and the coating film may be too thick.

The composition may further include a curing catalyst that is dibutyl tin dilaurate, and may further include various diol compounds as spacers.

The thermally conductive particles may include metal particles; can include The metal particles may be at least one selected from the group consisting of aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. The metal particles, specifically aluminum powder, can use flake-type particles with a diameter of 5 to 40 μm, and in addition to heat dissipation properties, they can produce a pearl effect on the coating film and help to strengthen the surface of the coating film. there is.

The thermally conductive particles may further include at least one carbon selected from the group consisting of carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon fibers.

Carbon nanotubes are a modified form of graphite, and include single-wall carbon nanotubes (SWCNT), in which a single layer of graphite is rolled into a tube, and multi-wall carbon nanotubes (multi-layer). -wall carbon nanotubes, MWCNTs). Carbon nanotubes have excellent mechanical properties and have a very high aspect ratio (length/diameter), so they have excellent tensile stress and excellent thermal conductivity, so their application range is diverse. In addition, it has the properties of a conductor or a semiconductor depending on its winding shape, its energy gap varies according to its diameter, and it has a quasi-one-dimensional structure, so it exhibits a unique quantum effect. The most important thermal property of carbon nanotubes is that they have very high thermal conductivity of 6,600 W/mK at room temperature, which has been theoretically proven to be due to the very large mean free path of phonons. MWCNTs can also give a thermal bridge effect between graphite or GNPs produced during milling, and graphene particles.

Graphene is a material with an atom-sized honeycomb structure made of carbon atoms. It has a thickness of 0.2 nm and has very high physical and chemical stability. It conducts electricity 100 times better than copper and has electron mobility 100 times higher than silicon. fast. In addition, its strength is more than 200 times stronger than steel, its thermal conductivity is more than twice as high as that of diamond, which has the highest thermal conductivity, and it transmits most of the light, so it is transparent and has excellent elasticity.

When carbon fiber has a strength of 10 to 20 g/d and a specific gravity of 1.5 to 2.1, it has excellent heat resistance and impact resistance and is strong against chemicals. During the heating process, molecules such as oxygen, hydrogen, nitrogen, etc. escape and the weight is reduced, so it is lighter than metal (aluminum), but has excellent elasticity and strength compared to metal (iron).

When the carbon material dispersion formed of such a carbon material is mixed with the graphite material, the carbon material such as carbon nanotubes contained in the carbon material dispersion is connected by covalent bonds between the particles of the graphite material, thereby improving the thermal conductivity and providing excellent heat dissipation performance.

The particle size of the carbon material may be preferably 200 nm to 1 μm. When the particle size of the carbon material is less than 200 nm, aggregation is likely to occur, and when the particle size exceeds 1 μm, it may be difficult to prepare a uniform dispersion of the carbon material in a state in which aggregation has already occurred. The amount of carbon may be 1% to 5% by weight in the heat dissipating paint composition. If the average particle size is too small, there is a problem in that the heat dissipation effect is low and sufficient heat dissipation is not achieved, and if the average particle size exceeds the above range, adhesion and coating are difficult when the heat dissipation paint is coated on a substrate for heat dissipation later. there is a problem.

If the carbon is less than 1% by weight in the heat dissipation paint composition, it is difficult to see the effect of thermal radiation due to a too small amount, and if it is more than 5% by weight, the aggregation of the fillers of heat dissipation characteristics increases, so that in the heat dissipation paint composition Acidity may be lowered, and adhesive strength may be lowered. The graphite and the carbon may have a weight ratio of 1:1 to 10:1 in the filler.

The thermally conductive particles may further include a heat dissipating filler.

The heat dissipating filler is porous silica (SiO ₂ ), alumina (alumina), aluminum oxide (Al ₂ O ₃ ), magnesium oxide, zinc oxide, silicon carbide (SiC), aluminum nitride, boron nitride, silicon nitride, hydroxide It may be at least one selected from the group consisting of magnesium, boron carbide (B ₄ C), silicon nitride (Si ₃ N ₄ ), boron oxide, and silicon oxide.

The heat dissipating filler may serve to increase milling efficiency in the milling process.

The heat dissipating filler may have an average particle diameter of 1 to 10 μm. If it exceeds the above range, the adhesion to the substrate is reduced, and workability may be deteriorated.

The heat dissipating filler may be selected without limitation as long as it has excellent thermal conductivity and heat dissipation in its material. In addition, the shape of the heat dissipating filler is not limited, and may be porous or non-porous in structure, and may be selected differently depending on the purpose. However, preferably, it is preferable to achieve excellent heat dissipation performance, easy formation of a heat dissipation coating film, uniform heat dissipation performance after forming the heat dissipation coating film, and surface quality of the heat dissipation coating film.

In heat-dissipating paints, the binder determines the thermal and mechanical strength of the coating film, so it can be selected according to the purpose. Urethane resin binders have the advantage of being able to design from thin films with high strength and heat resistance to flexible and elastic thin films.

The solvent may be selected according to the selected binder resin, curing agent, etc., so the present invention is not particularly limited thereto, and any solvent capable of properly dissolving each component may be used as the solvent. The solvent may specifically use an acetate solvent, more specifically N-butyl acetate, acetate, ethyl acetate, amyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol methyl acetate, diethylene glycol At least one selected from the group consisting of ethyl acetate, ethylene glycol monoethyl ether acetate, 3-methoxybutyl acetate, and propylene glycol methyl ether acetate (PGMEA) may be used.

The higher the added amount of the solvent, the lower the viscosity and the faster the sedimentation rate of the particles, and the smaller the added amount of the solvent, the higher the viscosity but the stability in the dispersion process may deteriorate. . The solvent may be 10% to 60% by weight of the heat dissipating paint composition. If the solvent is less than 10% by weight of the heat dissipating paint composition, the resin does not dissolve well, adhesion is not excellent, dispersibility is not good, and the viscosity becomes high, and if it is more than 60% by weight, the substrate for heat dissipation Gaps may be formed when the heat dissipating paint composition is coated, and the heat dissipation effect may be reduced.

In the case of spray coating, the viscosity of the paint can be adjusted by adding the solvent. For example, the weight ratio of the resin to the solvent may be 1:1. The content of the solvent can be adjusted according to the condition of the spray coater. In the case of bar coating, it may contain less than spray coating, as the viscosity should be slightly higher.

The composition may further include at least one or more selected from the group consisting of a matting agent, a colorant, an adhesion promoter, a dispersing agent, an antisettling agent, an antifoaming agent, and a leveling agent as additives.

The matting agent generally increases the surface emissivity to some extent and also serves to control the viscosity.

The matting agent is at least one selected from the group consisting of titanium dioxide, aerogel silica, hydrogel silica, PP wax, PE wax, PTFE wax, urea formaldehyde resin and benzoguamine formaldehyde resin, preferably may contain silica. The matting agent may be spherical particles having a diameter of 0.01 to 0.5 μm. The matting agent may be included in 2 to 5% by weight based on the total weight of the composition. In the case of the silica matting agent, it also affects the viscosity of the paint composition, but when an excessive amount is added, the viscosity becomes too high, and spraying may not be smooth during spray coating.

Meanwhile, the above-described heat-dissipating paint composition may further include a dispersant and a solvent for improving the dispersibility of the heat-dissipating filler and realizing a uniform heat-dissipating coating film.

The antifoaming agent prevents the generation and retention of air bubbles during mixing of each composition and prevents the generation of air bubbles or craters on the surface of a coating film.

The leveling agent may improve the uniformity of the coating film and reduce surface roughness.

In addition, the above-described heat-dissipating paint composition contains one or more additives such as a pH adjuster, a viscosity modifier, a thixotropy imparting agent, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, and a flame retardant. It could be. The various additives described above may be those known in the art and are not particularly limited in the present invention.

On the other hand, the above-described heat-dissipating paint composition may further include an antioxidant for preventing discoloration of the coated dry film, brittleness due to oxidation, and deterioration of physical properties such as adhesion strength.

The antioxidant may be a known component employed in the art as an antioxidant of a heat-dissipating paint composition. For example, the antioxidant is tri-methyl phosphate, tri-phenyl phosphate, tris (2, 4-di-tert-butylphenyl) phosphate, triethylene glycol-bis-3- (3-tert-butyl-4-hydride) Roxy-5-methylphenyl)propionate, 1,6-hexane-diol-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythrityl-tetrakis(3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, 2-hydroxybenzophenone, 2-hydroxyphenylbenzothiazole, hindered amine, organic nickel compound, salicylate, cinnamate derivatives, resorcinol monobenzoate, oxanilide, and p-hydroxybenzoate may include at least one selected from the group consisting of 2-hydroxyphenylbenzothia can be sleepy

In addition, the antioxidant may preferably be included in an amount of 0.1 to 3% by weight based on the total weight of the composition. If the antioxidant is provided in less than 0.1 parts by weight, discoloration and surface cracks may occur over a long time, and if the antioxidant is provided in more than 3 parts by weight, brittleness and adhesive strength may be weakened.

The adhesion promoter may be epoxy ester phosphate acid. The adhesion enhancer improves the interfacial adhesion between the coating film and the adherend, and prevents peeling and cracking of the coating film even during thermal shock and long-term use. The adhesion promoter may be included in an amount of 3 to 10% by weight based on the total weight of the composition.

The dispersant may be included in an amount of 0.1 to 1.5% by weight based on the total weight of the composition. If it is less than 0.1% by weight, the filler may not be well dispersed, and aggregation may increase. If the dispersant is provided in excess of 1.5% by weight, the adhesion strength of the adherend may be weakened, pin holes and orange peel may occur on the surface of the coating film, and there is a risk of deterioration in adhesive strength.

The dispersant may be included to increase the dispersibility of the heat dissipating paint composition, to make the density even, and to appropriately adjust the rheology control.

As the dispersing agent, it is preferable to use a nonionic surfactant. When the heat dissipating paint composition of the present application is stored for 4 weeks or more, the effect of improving the storage stability of the nonionic surfactant is more excellent. Surfactant increases the storage stability of the composition by reducing the surface tension of the dispersion medium and the dispersion phase, and helps to form a coating film by lowering the surface tension of the coated film surface and the composition.

The anti-settling agent controls the flowability of the composition and serves to prevent or slow down the sedimentation and caking phenomena of the particles. The anti-settling agent may use a urea-based compound or an amide-based compound, and may prevent sedimentation of thermally conductive particles having a high specific gravity.

The heat-dissipating paint composition includes an anti-settling agent dispersed in the binder resin, and in this case, the anti-settling agent may be included in an amount of 0.5 to 1% by weight based on the total weight of the composition.

mixing the heat-dissipating paint composition into a mixer such as a dissolver; preparing a dispersion by milling the mixed mixture; manufactures, including

In the stirring step, the composition may be put into a stirrer and, for example, stirring may be performed at a speed of 50 rpm to 1500 rpm for 10 minutes to 1 hour. If the stirring time is too short, it is difficult to achieve uniform mixing, and even if the stirring time is too long, it is difficult to expect a more uniform mixing effect.

The milling may be performed by at least one method selected from the group consisting of roll milling, ball milling, jet milling, screw mixing, attrition milling, bead milling, basket milling, revolution mixing, and super mill.

Before the step of preparing the dispersion, the step of sonicating the graphite; may further include.

The application is performed using various methods including at least one selected from the group consisting of spray coating, roll printing, dipping coating, comma coating, slit die coating, gravure coating, roll-to-roll, and bar coating. Available. The thickness of the coating can be used for manufacturing various heat dissipation substrates and coating heat sinks, and may be formed to a thickness of 10 μm to 100 μm, more specifically, 30 μm to 70 μm, in consideration of optimal heat dissipation characteristics. In this range, heat dissipation performance is the best, and if the thickness is too thin, the strength and durability of the coating film is reduced.

First, one surface of the metal thin film is coated with an adhesive layer, and the opposite surface is coated with a heat-dissipating paint composition to prepare a heat-dissipating adhesive sheet.

The adhesive layer may be sequentially formed by commer coating and the heat dissipation layer by spray coating, respectively. For example, the adhesive layer and the heat dissipation layer may be formed by commer coating at the same time, but in this case, productivity may be lowered considering the thickness difference between the adhesive layer and the heat dissipation layer and the curing temperature and time.

A heat-dissipating paint composition is applied on a metal thin film, fired at 120°C to 180°C for 10 minutes to 1 hour in the case of a one-component type, and fired at 70°C to 100°C for 10 minutes to 1 hour in the case of a two-component type to form a heat-dissipating layer. form

Although the present application will be described in more detail through the following examples, the following examples are not intended to limit the scope of the present application, which should be interpreted to aid understanding of the present application.

Hereinafter, Examples, Comparative Examples, and Experimental Examples of the present application will be described.

<Example 1> Preparation of heat dissipation layer heat dissipation paint

Acrylic polyol (OH value 90) 20 parts by weight, caprolactone polyol (OH value 280, MW 400) 20 parts by weight, expanded graphite (average particle size 50 μm) 9.0 parts by weight, aluminum powder (Flake, average particle size 25 μm) 4.2 parts by weight Part, porous SiO ₂ (average particle size 4 μm) 3.2 parts by weight, phosphoric acid epoxy ester 8.5 parts by weight, dispersing agent (phosphoric ACID ester of polyethoxylated alkyl phenol) 0.5 parts by weight, silicone-based antifoaming agent (AFCONA 2722) 1.0 parts by weight, anti-settling agent (urea ) 0.4 parts by weight, slip agent (polyether polysiloxane) 0.5 parts by weight. 12.5 parts by weight of N-butyl acetate and 20 parts by weight of PMA (propylene glycol monomethyl ether acetate) were uniformly mixed with a dissolver mixer. The mixture was transferred to a basket mill and milled for 3 hours. The viscosity of the final paint was 520 cps.

<Example 2> Preparation of heat dissipation layer heat dissipation paint

It is the same as Example 1 except that impression graphite was used instead of expanded graphite in Example 1.

<Example 3> Manufacturing of aluminum heat dissipation adhesive sheet

The heat-dissipating paint prepared in Example 1 was spray-coated on the surface of an aluminum adhesive film with a total thickness of 70 μm composed of aluminum foil (thickness 47 μm) and acrylic adhesive (thickness 25 μm), and then cured at 80 ° C for 30 minutes to form a heat-radiating layer was formed. The heat dissipation layer had a thickness of 40 to 50 μm.

<Experimental Example 1> Measurement of heat dissipation performance

The aluminum heat dissipating adhesive sheet prepared in Example 3 was cut into a size of 3 cm x 10 cm and attached to an aluminum sheet (thickness: 0.3 mm) of the same width and length. A 3W ceramic heater having a width of 2 cm each was attached to the bottom of the aluminum sheet using a thermal pad, and temperature sensors were installed at three locations, respectively, as shown in FIG. 3 . After power was applied to the ceramic heater, the temperatures of the three measurement points were balanced, and then the temperatures were recorded. The experiment was conducted in an environment of 40 ℃ (Ch.3) without air convection.

<Comparative Example 1> Measurement of heat dissipation performance

It is the same as Experimental Example 1 except for using the aluminum adhesive sheet, which is a raw material, instead of the aluminum heat radiation adhesive sheet.

<Experimental Example 2> Measurement of heat dissipation performance

It is the same as Experimental Example 1 except that the experiment was conducted indoors at a temperature of 24 ° C.

<Comparative Example 2> Measurement of heat dissipation performance

It is the same as Experimental Example 2 except that the aluminum adhesive sheet, which is a raw material, is used instead of the aluminum thermal radiation adhesive sheet of Example 3.

The heat dissipation performance measurement results of the experimental examples and comparative examples are shown in Table 1 below.

Ch.1 Ch.2 Ch.3 Experimental Example 1 86.8 ℃ 61.6 ℃ 39.9 ℃ Comparative Experimental Example 1 99.0 ℃ 67.9 ℃ 39.9 ℃ Experimental Example 2 67 ℃ 43℃ 24℃ Comparative Experimental Example 2 76 ℃ 50 ℃ 24℃

As can be seen from Table 1 above, it can be seen that the heat dissipation and cooling effect of the aluminum heat dissipation adhesive sheet formed with the heat dissipation layer is far superior to that of the aluminum adhesive film. It can be seen that the temperature of the heat source was lowered by more than 12 ℃ only by radiant heat in the absence of convection and by 9 ℃ in the room with convection.

<Experimental Example 3> Measurement of heat dissipation efficiency

The results of measuring the heat dissipation efficiency according to the milling time of the compositions of Examples 1 and 2 are shown in FIG. 4 . In the case of expanded graphite, it can be seen that the heat dissipation efficiency is very good when milled for 3 hours or more. Heat radiation efficiency was expressed as temperature reduction efficiency (based on °C) compared to existing commercially available paints.

<Experimental Example 4> Measurement of thermal conductivity

For Example 1, the thermal conductivity was measured according to the milling time at 25° C. and is shown in FIGS. 5 and 6. In FIG. 5 , the vertical thermal conductivity of the heat dissipation layer formed by milling the composition of Example 1 for 3 hours was 1.4 W/m.K. In FIG. 6, the horizontal thermal conductivity of the coating film formed by milling for 3 hours was 5.2 W/m.K, so it can be seen that the thermal conductivity was very excellent when milled for 3 hours.

7 shows expanded graphite before milling, FIG. 8 shows a SEM picture of expanded graphite after milling for 3 hours, and FIG. 9 shows a TEM picture of expanded graphite after milling for 3 hours.

Those skilled in the art to which this application pertains will understand that this application can be implemented in other specific forms without changing its technical spirit or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The scope of the present application is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present application.

This patent was applied for through a technology development support project in the field of materials parts and equipment in Chungbuk, supported by Chungbuk Province and the Chungbuk Institute of Science and Technology Innovation in the Republic of Korea.

10: heat dissipation layer 20: metal thin film layer
30: adhesive layer 40: release layer
200: aluminum substrate 300: ceramic heater

Claims (13)

heat dissipation layer;
At least one metal thin film layer formed on the lower surface of the heat dissipation layer; and
Including; adhesive layer formed on the lower surface of the metal thin film layer,
The heat dissipation layer,
70 to 85% by weight of a binder resin, 12 to 25% by weight of thermally conductive particles, and 3 to 10% by weight of an additive based on the total weight of a composition forming a heat dissipation layer,
The binder resin,
Contains a urethane resin or an epoxy resin,
The thermally conductive particles,
Including expanded graphite particles and metal particles,
The expanded graphite particles,
It is milled for 2 to 5 hours to separate graphene nanoplates (GNP) and graphene from graphite.
A mixture of two or more of graphite particles, graphene nanoplate particles, and graphene particles,
The expanded graphite particle diameter is a heat dissipation adhesive sheet, characterized in that 0.1 ~ 50 μm. The method of claim 1,
The metal thin film layer,
One selected from the group consisting of aluminum (Al), gold (Au), silver (Ag), nickel (Ni), tin (Sn), zinc (Zn), tungsten (W), iron (Fe), and alloys thereof including more than
Heat dissipation adhesive sheet, characterized in that the thickness of the metal thin film layer is 20 to 500 ㎛. The method of claim 1,
The adhesive layer,
Includes at least one or more selected from the group consisting of acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives;
Heat dissipation adhesive sheet, characterized in that the thickness of the adhesive layer is 5 ~ 50 ㎛. The method of claim 1,
The adhesive layer,
Characterized in that it comprises at least one thermally conductive particle selected from the group consisting of graphite, carbon black, alumina, aluminum nitride (AlN), boron nitride (BN), graphene, graphite powder, and carbon nanotube (CNT) Heat dissipation adhesive sheet. The method of claim 1,
Heat dissipation adhesive sheet, characterized in that it further comprises a release layer on the lower surface of the adhesive layer. The method of claim 1,
The heat dissipation layer,
It is formed as a one-part composition or a two-part composition,
Heat dissipation adhesive sheet, characterized in that the thickness of the heat dissipation layer is 10 ~ 100 ㎛. The method of claim 6,
The two-part composition,
A heat dissipation adhesive sheet characterized in that a diisocyanate-based curing agent or an amine-based curing agent is added to a main composition containing a binder resin that is a urethane resin or an epoxy resin, mixed, and calcined at 70 ° C to 100 ° C to form a heat radiation layer. The method of claim 6,
The one-component composition,
The main component of the binder resin is polyol,
Forming a composition further comprising 25 to 40% by weight of block isocyanate in the total composition,
A heat-dissipating adhesive sheet characterized in that a heat-dissipating layer is formed by firing at 120 ° C to 180 ° C. delete The method of claim 1,
The milling beads used in the milling,
Heat dissipation adhesive sheet, characterized in that zirconia with a diameter of 0.05 ~ 3.0 mm. The method of claim 1,
The composition,
A heat dissipation adhesive sheet further comprising 0.5 to 1.5% by weight of a nonionic surfactant based on the total weight of the composition. The method of claim 6,
The one-component composition or two-part composition,
N-butyl acetate, acetate, ethyl acetate, amyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol methyl acetate, diethylene glycol ethyl acetate, ethylene glycol monoethyl ether acetate and 3-methoxybutyl acetate A heat dissipation adhesive sheet comprising at least one acetate-based solvent selected from the group consisting of, propylene glycol methyl ether acetate (PGMEA). The method of claim 1,
The metal particles,
at least one selected from the group consisting of aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium;
Heat dissipation adhesive sheet, characterized in that the flake type with a diameter of 5 ~ 40 μm.

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