Curable composition, heat dissipation material, and article

Abstract

The present invention provides a curable composition which secures an appropriate pot life, has a good dispersion state of an inorganic filler, is excellent in terms of adhesion to the surface of a heating element, a radiator or the like without using silicone, can be cured under a room temperature condition, and can form a heat dissipation material that can be easily separated by means of heating. Provided is a two-pack type curable composition which includes a combination of a main agent and a curing agent, and which is used for the purpose of forming a heat dissipation material. The main agent contains a polyamine (A), a polyol (C), and an inorganic filler (D1). The curing agent contains a polyisocyanate (B) and an inorganic filler (D2). The content of the polyamine (A) in the total of the polyamine (A) and the polyol (C) in the main agent is 50-90 mass%. The ratio of the number of moles of isocyanate groups in the curing agent to the total number of moles of amino groups and hydroxyl groups in the main agent is 0.75 to 2.50.

Description

Curable composition, heat dissipating material, and article

[0001] The present invention relates to a curable composition, a heat dissipating material, and an article.

[0002] As integrated circuits become increasingly denser, the amount of heat generated inside electronic devices tends to increase, necessitating the development of technologies for efficiently dissipating heat generated inside electronic components. For example, thermal interface materials (TIMs), such as heat-dissipating sheets with excellent thermal conductivity, are known and placed between heat-generating elements, such as electronic components, and heat sinks or other heat sinks inside electronic devices. The use of such thermal interface materials fills the minute gaps between the surfaces of the heat-generating elements and the heat sink, reducing contact thermal resistance and enabling the heat from the heat-generating elements to be transferred appropriately to the heat sink.

[0003] For example, a heat-resistant elastic material in which a thermally conductive material is dispersed in a silicone polymer precursor has been proposed (Patent Document 1). However, there is a strong demand to avoid the use of silicone from the viewpoint of avoiding a decrease in insulating performance due to the generation of low-molecular-weight siloxane, which is a volatile component. For this reason, heat dissipation materials using non-silicone polymers as binder components and compositions for forming such heat dissipation materials have been studied.

[0004] For example, a thermally conductive polymer molded body has been proposed in which a polymerizable resin composition containing a polymerizable resin component such as a polyol and aluminum hydroxide is cured under heating conditions using a curing agent such as an isocyanate (Patent Document 2). Also proposed is a thermally conductive cured product in which a binder component containing a polyurethane polyurea resin having a carboxyl group and a thermally conductive filler is cured under heating conditions using an epoxy compound (Patent Document 3). Furthermore, a silicone-free thermal interface has been proposed in which a composition containing a component having a reactive functional group such as a polyol and a thermally conductive filler is heat-cured (Patent Document 4).

[0005] Japanese Patent Application Laid-Open No. 2005-209955 Japanese Patent Application Laid-Open No. 2015-530470 Japanese Patent Application Laid-Open No. 2020-200454 Japanese Patent Application Laid-Open No. 2023-508288

[0006] However, the compositions proposed in Patent Documents 2 to 4 all require curing under heating conditions, necessitating the provision of a heat source in the device production line. This complicates the process of placing the heat dissipation material in the desired location, poses issues such as the time required for curing, and is not desirable in terms of carbon neutrality efforts. Furthermore, after curing, it is difficult to remove the material from the heating element, making it difficult to meet needs such as separate disposal after use, and repairability and recyclability are not necessarily good.

[0007] The present invention has been made in consideration of the problems associated with the prior art, and an object of the present invention is to provide a curable composition that ensures an appropriate pot life, has a good dispersion state of the inorganic filler, and has excellent adhesion to the surfaces of heating elements, radiators, etc. without the use of silicone, can be cured under room temperature conditions, and can form a heat dissipation material that can be easily peeled off by heating. Another object of the present invention is to provide a heat dissipation material that is a cured product obtained by curing the above-mentioned curable composition, and an article using this heat dissipation material.

[0008] That is, the present invention provides the following curable compositions: [1] A two-component curable composition used to form a heat dissipating material, comprising a combination of a main component and a curing agent, wherein the main component contains a polyamine (A), a polyol (C), and an inorganic filler (D1), the curing agent contains a polyisocyanate (B) and an inorganic filler (D2), the content of the polyamine (A) in the main component relative to the total of the polyamine (A) and the polyol (C) is 50 to 90 mass%, and the ratio (NCO / (NH+OH)) of the number of moles of isocyanate groups in the curing agent to the total number of moles of amino groups and hydroxyl groups in the main component (NH+OH) is 0.75 to 2.50. [2] The curable composition according to [1], wherein the amine value of the polyamine (A) is 300 mgKOH / g or less. [3] The curable composition according to [1] or [2], wherein the polyisocyanate (B) is an aliphatic polyisocyanate. [4] The curable composition according to any one of [1] to [3], wherein the inorganic filler (D1) and the inorganic filler (D2) are each independently at least one selected from the group consisting of metals, metal oxides, metal nitrides, metal hydroxides, and metal carbonates. [5] The curable composition according to any one of [1] to [3], wherein the inorganic filler (D1) and the inorganic filler (D2) are each independently at least one selected from the group consisting of alumina, aluminum nitride, aluminum hydroxide, magnesium oxide, zinc oxide, boron nitride, and magnesium hydroxide. [6] The curable composition according to any one of [1] to [5], wherein the loading rate of the inorganic filler (D1) in the base resin is 70 to 95 mass%, and the loading rate of the inorganic filler (D2) in the curing agent is 50 to 95 mass%.

[0009] The present invention also provides the following heat dissipating materials. [7] A heat dissipating material that is a cured product obtained by curing the curable composition according to any one of [1] to [6] above. [8] The heat dissipating material according to [7] above, which has a thermal conductivity of 2.0 W / (m K) or more. [9] The heat dissipating material according to [7] or [8] above, in which the total filling rate of the inorganic filler (D1) and the inorganic filler (D2) is 65 to 95 mass%.

[0010] Furthermore, according to the present invention, the following article is provided:

[10] An article comprising a heat generating element and the heat dissipation material according to any one of [7] to [9] above, which is placed in contact with the heat generating element.

[0011] According to the present invention, it is possible to provide a curable composition capable of forming a heat dissipation material that ensures an appropriate pot life, has a good dispersion state of the inorganic filler, and has excellent adhesion to the surface of a heating element, a radiator, etc. without using silicone, is curable under room temperature conditions, and is easily peelable by heating. Furthermore, according to the present invention, it is possible to provide a heat dissipation material that is a cured product obtained by curing the above-mentioned curable composition, and an article using this heat dissipation material.

[0012] <Curable Composition> Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the curable composition of the present invention is a two-component curable composition used to form a heat dissipation material, comprising a combination of a base agent and a curing agent. The base agent contains polyamine (A), polyol (C), and inorganic filler (D1), and the curing agent contains polyisocyanate (B) and inorganic filler (D2). In the base agent, the content of polyamine (A) relative to the total of polyamine (A) and polyol (C) is 50 to 90 mass%. Furthermore, the ratio (NCO / (NH+OH)) of the number of moles of isocyanate groups in the curing agent to the total number of moles of amino groups and hydroxyl groups in the base agent (NH+OH) is 0.75 to 2.50. The curable composition of this embodiment will be described in detail below.

[0013] (Main Agent) The curable composition of this embodiment is a two-part curing composition containing a combination of a main agent and a curing agent, and is a composition set of the type in which the two parts (two components) are mixed and then cured under predetermined conditions. The main agent (first agent) contains polyamine (A), polyol (C), and inorganic filler (D1), and is preferably a composition essentially consisting of only polyamine (A), polyol (C), and inorganic filler (D1). The main agent is preferably a solvent-free composition that does not substantially contain a liquid medium.

[0014] The polyamine (A) is a component having two or more amino groups in its molecule, which reacts with the polyisocyanate (B) in the curing agent to form a urea bond. The polyamine (A) reacts with the polyisocyanate (B) faster than the polyol (C) also contained in the base resin. Therefore, the use of the polyamine (A) allows for the rapid formation of a urea bond and the development of initial physical properties (normal adhesion).

[0015] The polyamine (A) also functions as a dispersant for uniformly dispersing the inorganic filler (D1) in a good state in the base resin. Therefore, by using the polyamine (A), it is possible to increase the filling rate (content) of the inorganic filler (D1), and it is possible to form a heat dissipation material that is a cured product that is excellent in thermal conductivity and is less likely to have uneven physical properties such as thermal conductivity and adhesion.

[0016] When a base agent containing a dispersant (excluding polyamine (A)) that disperses the inorganic filler is used, the dispersant may bleed out from the formed heat dissipation material, which may lead to a decrease in the adhesion of the heat dissipation material. In contrast, the polyamine (A), which can also function as a dispersant, is incorporated into the molecules of the polymer (polyurethane polyurea resin) by reacting with the polyisocyanate (B), so it does not bleed out from the formed heat dissipation material. Therefore, by using a base agent that does not substantially contain a dispersant (excluding polyamine (A)) that disperses the inorganic filler (D1), it is expected that the dispersant will not bleed out from the formed heat dissipation material and that a heat dissipation material in which the decrease in adhesion over time is suppressed will be formed.

[0017] The amine value of the polyamine (A) is preferably 300 mgKOH / g or less, more preferably 20 to 250 mgKOH / g, and particularly preferably 70 to 200 mgKOH / g. Polyamines (A) with an amine value of more than 300 mgKOH / g have small molecules and therefore tend to have a high reaction rate. This can lead to increased heat generation during curing and a slightly shorter usable life.

[0018] The base agent may contain two or more polyamines (A). When the base agent contains two or more polyamines (A), the "amine value of the polyamine (A)" is the maximum value (maximum amine value) among the amine values ​​of the two or more polyamines.

[0019] The polyol (C) is a component having two or more hydroxyl groups in its molecule, which reacts with the polyisocyanate (B) in the curing agent to form a urethane bond. The polyol (C) reacts slower with the polyisocyanate (B) than the polyamine (A) also contained in the base resin. Therefore, by using the polyamine (A) and the polyol (C) in combination, urea bonds are quickly formed and the initial physical properties are developed, and then the remaining polyisocyanate (B) and the polyol (C) react gently to form a urethane bond, so that a heat dissipation material with excellent adhesion can be formed while ensuring a sufficient usable time.

[0020] The hydroxyl value of the polyol (C) is not particularly limited and is typically 50 to 1,500 mgKOH / g, and from the viewpoint of adjusting the reaction rate and usable life, it is preferably 100 to 1,250 mgKOH / g. If the hydroxyl value of the polyol (C) is too low, the reaction rate at room temperature tends to be slow, and it may be difficult to ensure normal adhesion. On the other hand, if the hydroxyl value of the polyol (C) is too high, the reaction rate at room temperature tends to be too fast, and the usable life may be shortened.

[0021] Examples of the polyol (C) include polycarbonate diols and polyester diols. Examples of the polycarbonate diol include a reaction product of a dialkyl carbonate, such as dimethyl carbonate, with a diol compound having two hydroxyl groups in the molecule. Commercially available polycarbonate diols can also be used. Examples of the diol compound include linear or side-chain diols having 2 to 10 carbon atoms.

[0022] Examples of diol compounds include aliphatic diols and alicyclic diols. Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, and 2-methyl-1,8-octanediol. Examples of alicyclic diols include 1,4-cyclohexanedimethanol. From the viewpoint of further improving the flexibility of the polyurethane resin, aliphatic diols are preferred, and 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol are more preferred.

[0023] Examples of polyester diols include those obtained by condensation polymerization of at least one of aliphatic dicarboxylic acids and aromatic dicarboxylic acids with low molecular weight glycols. Examples of aliphatic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, glutaric acid, and azelaic acid. Examples of aromatic dicarboxylic acids include isophthalic acid and terephthalic acid. Examples of low molecular weight glycols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 3-methylpentanediol, 1,6-hexamethylene glycol, neopentyl glycol, and 1,4-bishydroxymethylcyclohexane.

[0024] As the polyol (C), polymer polyols other than the above-mentioned polycarbonate diols and polyester diols can also be used. Examples of polymer polyols other than polycarbonate diols include polyether diols, polylactone diols, dimer diols, and other polymer polyols. Furthermore, short-chain diols having a molecular weight of 400 or less can also be used in combination.

[0025] Among these, it is preferable to use a polyol having a side chain in its molecular structure as the polyol (C). Examples of polyols having a side chain in their molecular structure include short-chain diols such as 1,2-propylene glycol, 1,3-butylene glycol, 2-methylpropanediol, 3-methylpentanediol, 1,2-butanediol, and 1,2-hexanediol; polyester-based diols containing structural units derived from diols having branched alkyl chains such as neopentanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2-butyl-2-ethyl-1,3-propanediol; polycarbonate-based diols; polyether-based diols such as polypropylene glycol; polybutadiene polyols; and polyols derived from castor oil. When a polyol having a side chain is used, the side chain interacts with the inorganic filler, improving the dispersibility of the inorganic filler. This allows the curable composition to have a relatively low viscosity and be more easily used as a coating material.

[0026] The content of polyamine (A) in the base resin relative to the total of polyamine (A) and polyol (C) is 50 to 90% by mass, preferably 60 to 85% by mass, and more preferably 70 to 80% by mass. If the content of polyamine (A) relative to the total of polyamine (A) and polyol (C) is less than 50% by mass, curing at room temperature (25°C) becomes difficult or the curing time becomes too long. On the other hand, if the content of polyamine (A) relative to the total of polyamine (A) and diol (C) exceeds 90% by mass, the curing rate becomes too fast and the usable time becomes insufficient. Furthermore, the content of polyol (C) relative to the total of polyamine (A) and polyol (C) in the base resin is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and particularly preferably 20 to 30% by mass.

[0027] The inorganic filler (D1) in the base agent and the inorganic filler (D2) in the curing agent are both inorganic components having thermal conductivity. That is, both the base agent and the curing agent constituting the cured composition of this embodiment contain an inorganic filler. By including an inorganic filler in both the base agent and the curing agent, the base agent and the curing agent can be uniformly mixed, and a heat dissipation material can be formed, which is a cured product in which the inorganic filler is uniformly dispersed.

[0028] The inorganic filler (D1) in the base resin and the inorganic filler (D2) in the curing agent may be the same type or different types. The base resin contains a polyamine (A) that can also function as a dispersant. Therefore, the base resin can be filled (contained) with a relatively large amount of inorganic filler (D1). Specifically, the filling rate of inorganic filler (D1) in the base resin is preferably 70 to 95% by mass, more preferably 80 to 95% by mass. The filling rate of inorganic filler (D2) in the curing agent is preferably 50 to 95% by mass, more preferably 85 to 90% by mass.

[0029] The inorganic filler (D1) and the inorganic filler (D2) are preferably each independently at least one selected from the group consisting of metals, metal oxides, metal nitrides, metal hydroxides, and metal carbonates. Examples of metals (semimetals) include gold, silver, copper, aluminum, magnesium, zinc, boron, silicon, and alloys containing these. Examples of metal oxides include alumina, calcium oxide, magnesium oxide, zinc oxide, beryllia, titanium oxide, and silica. Examples of metal nitrides include aluminum nitride, boron nitride, carbon nitride, and silicon nitride. Examples of metal hydroxides include aluminum hydroxide, magnesium hydroxide, and calcium hydroxide. Examples of metal carbonates include calcium carbonate, magnesium carbonate, and hydrotalcite. The inorganic fillers can be used alone or in combination. Among these, alumina, aluminum nitride, aluminum hydroxide, magnesium oxide, zinc oxide, boron nitride, and magnesium hydroxide are preferred.

[0030] Examples of the particle shape of the inorganic filler (D1) and the inorganic filler (D2) include spherical, acicular, flaky, dendritic, fibrous, and amorphous shapes. The average particle diameter of the inorganic filler (D1) and the inorganic filler (D2) is not particularly limited, and may be, for example, within the range of 0.1 to 100 μm. The term "average particle diameter" as used herein refers to the cumulative 50% particle diameter (median diameter; D) on a volume basis measured by a laser diffraction scattering method. ５０ )

[0031] (Curing Agent) The curing agent (second agent) contains a polyisocyanate (B) and an inorganic filler (D2), and is preferably a composition substantially composed of only the polyisocyanate (B) and the inorganic filler (D2). Therefore, this curing agent reacts quickly with the hydroxyl groups and amino groups in the base agent. The curing agent is preferably a solvent-free composition that does not substantially contain a liquid medium.

[0032] The polyisocyanate (B) is a compound having two or more isocyanate groups in its molecule. Examples of the polyisocyanate (B) include aliphatic polyisocyanates, aromatic polyisocyanates, and alicyclic polyisocyanates. The aliphatic polyisocyanates include modified aliphatic polyisocyanates.

[0033] Aliphatic polyisocyanates include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), and 1,10-decamethylene diisocyanate.

[0034] Examples of aromatic polyisocyanates include 4,4'-diphenylmethane diisocyanate (MDI), 2,2'-MDI, 2,4'-MDI, polymeric MDI, 2,4-tolylene diisocyanate (TDI), 2,6-TDI, m-xylylene diisocyanate (XDI), 1,4-phenylene diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, and benzidine diisocyanate.

[0035] Examples of the modified aliphatic polyisocyanate include isocyanurates, allophanates, biurets, and adducts of aliphatic polyisocyanates with polyols (such as trimethylolpropane).

[0036] The polyisocyanate (B) is preferably an aliphatic polyisocyanate. The reaction rate of an aliphatic polyisocyanate with the polyol (C) is slower than that of an aromatic polyisocyanate. Therefore, by using an aliphatic polyisocyanate, the usable time of the curable composition can be more sufficiently ensured. It is also preferable to use an aliphatic polyisocyanate and an aromatic polyisocyanate in combination to adjust the usable time.

[0037] Furthermore, the polyisocyanate (B) is more preferably an aliphatic polyisocyanate-modified product, and among the aliphatic polyisocyanate-modified products, a nurate product is particularly preferred. When an aliphatic polyisocyanate-modified product is used, a heat dissipation material that is a three-dimensional cured product can be formed. That is, even when cured under room temperature conditions, a heat dissipation material that is a cured product with improved room temperature adhesion can be formed.

[0038] The curing agent contains a polyisocyanate (B) that has a certain degree of reactivity, and therefore it is preferable to use an inorganic filler (D2) that has a low reactivity with the polyisocyanate (B).

[0039] The ratio (NCO / (NH+OH)) of the number of moles of isocyanate groups in the curing agent (NCO) to the total number of moles of amino groups and hydroxyl groups in the base resin (NH+OH) is 0.75 to 2.50, preferably 1.00 to 1.95, and more preferably 1.75 to 1.90. By setting the value of "NCO / (NH+OH)" within the above range, it is possible to obtain a room-temperature curable composition that has excellent adhesion while ensuring an appropriate pot life and is capable of forming a heat-dissipating material that can be peeled off by heating.

[0040] (Other Components) Various additives can be added to the curable composition of the present embodiment as needed. Examples of additives include coupling agents for improving substrate adhesion, ion scavengers for improving insulation reliability during moisture absorption, various dispersants, and leveling agents. The curable composition of the present embodiment is preferably a so-called silicone-free composition that does not substantially contain silicone. The curable composition of the present embodiment can form a heat dissipation material that has excellent adhesion to the surfaces of heating elements, radiators, etc., even without using silicone.

[0041] (Method for producing curable composition) The main agent and the curing agent can be obtained by mixing the above-mentioned components according to a conventional method. Then, the obtained main agent and the curing agent can be appropriately combined to obtain the desired two-component curing type curable composition.

[0042] The viscosity of the base agent and curing agent at 20°C is preferably 100 to 1,000 Pa·s, respectively. If the viscosity is less than 100 Pa·s, the inorganic filler may be more likely to settle, resulting in slightly reduced storage stability. On the other hand, if the viscosity exceeds 1,000 Pa·s, the discharge pressure during coating may become excessively high, which may lead to problems in practical use. Considering storage stability and suitability for coating use, it is more preferable that the viscosity of the base agent and curing agent at 20°C is 200 to 750 Pa·s, respectively. Furthermore, if the viscosity of the base agent at 20°C is 300 to 750 Pa·s and the viscosity of the curing agent at 20°C is 200 to 550 Pa·s, the difference in viscosity between these two agents is relatively small, making them easier to mix, which is particularly preferable in terms of suitability for use.

[0043] <Heat Dissipating Material> One embodiment of the heat dissipating material of the present invention is a cured product obtained by curing the curable composition described above. After mixing the base and curing agent constituting the curable composition, the composition is applied to the surface of a heat-generating element such as a heat-generating electronic component or a heat sink or other heat dissipating device according to a conventional method. The composition is then cured by holding it at room temperature (approximately 25°C) for a predetermined time without heating, thereby forming the desired heat dissipating material at the desired location. The curing time can be set by appropriately adjusting the content of polyamine (A) in the total of polyamine (A) and polyol (C) in the base material, or the ratio (NCO / (NH+OH)) of the number of moles of isocyanate groups in the curing agent to the total number of moles of amino groups and hydroxyl groups in the base material (NH+OH). Specifically, the composition can be cured within a holding time of approximately 6 to 48 hours.

[0044] Since the curable composition is a composition that can be cured at room temperature, even when formed on the surface of a heat-sensitive component (such as a CPU), it can be cured without substantially damaging such a component to form the desired heat dissipation material. The thermal conductivity of the heat dissipation material thus formed is typically 2.0 W / (m·K) or more, preferably 2.5 W / (m·K) or more, and more preferably 2.5 to 4.0 W / (m·K). The total filling rate of the inorganic filler (D1) and the inorganic filler (D2) in the heat dissipation material thus formed is preferably 65 to 95 mass%. For this reason, the heat dissipation material of this embodiment is useful as a heat dissipation material (TIM), such as a heat dissipation sheet, disposed between a heat-generating electronic component or other heat source provided inside an electronic device and a heat sink or other heat sink.

[0045] To apply a two-component curing curable composition to a desired location, for example, it is preferable to mix the two components (two liquids) in a flow path and use a two-component mixing static mixer (dispenser) equipped with a nozzle capable of ejecting the liquid mixture of the two components from the tip, and extrude the curable composition from the tip of the nozzle while mixing the two components (base and curing agent). The above-mentioned curable composition has a sufficient pot life, and even when the base and curing agent are mixed, they do not immediately harden under room temperature conditions, making it easy to apply to the desired location. Furthermore, since the curable composition can be extruded from the tip of a thin nozzle while maintaining a pot life, it can be injected into narrow gaps between components, making it highly versatile.

[0046] The heat dissipation material of this embodiment has excellent adhesion to the surfaces of various substrates, but can be easily peeled off from the surfaces of the substrates by heating. To peel off the heat dissipation material, for example, it is sufficient to heat it at 80 to 120°C for 30 minutes or more. By heating in this way, the adhesion (adhesion) decreases, and the heat dissipation material can be easily peeled off from the surface of the substrate, etc., so the heat dissipation material of this embodiment has excellent recyclability (repairability).

[0047] <Article> One embodiment of the article of the present invention includes a heat generating element and the above-described heat dissipation material arranged in contact with the heat generating element. Examples of the heat generating element include various circuit boards, as well as electronic components such as semiconductor devices and Peltier devices. Examples of the semiconductor device include power modules such as power semiconductor devices, LEDs, and inverter devices. The semiconductor device is equipped with, for example, semiconductor elements such as insulated gate bipolar transistors, diodes, and IC chips; and various heat generating elements such as resistors and capacitors.

[0048] Even when silicone-free, the heat dissipation material has excellent adhesion to the surfaces of heat-generating elements and heat sinks, and has high thermal conductivity. Furthermore, since the heat dissipation material can be formed under room temperature conditions, it is suitable for application to heat-sensitive heat-generating elements such as electronic components. Furthermore, since the heat dissipation material can be easily peeled off by applying moderate heat, it is also highly recyclable.

[0049] Even if the heat dissipation material is placed in contact with a heat generating element, it will not easily peel off due to the heat of the heat generating element if it is in contact with a heat dissipator (cooling part) such as a heat sink or radiator to dissipate heat. On the other hand, when the cooling part is stopped functioning, the adhesion decreases, so it can be easily peeled off, disassembled, and recycled.

[0050] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0051] <Preparation of Materials> Various materials shown in Table 1 were prepared. In Table 1, "OH1" and "OH2" are both polyols having side chains (branched structures). "OH1" is a polyester-based diol containing structural units derived from 3-methyl-1,5-pentanediol, "OH2" is 1,3-butanediol (1,3-butylene glycol), and "OH3" is a polyol derived from castor oil. Furthermore, "NCO1" and "NCO2" are both aliphatic polyisocyanates (aliphatic polyisocyanate-modified products (nurate products)). Furthermore, the particle shapes of "fillers 8-9, 13-16" are all spherical, the particle shape of "filler 10" is irregular, and the particle shape of "filler 12" is scaly.

[0052]

[0053] <Breakdown of Main Component> (Breakdown a01) A mixing vessel equipped with a stirrer, reflux condenser, thermometer, nitrogen inlet tube, and manhole was prepared. While the inside of this mixing vessel was purged with nitrogen gas, 1.5 parts of NH4, 7 parts of NH5, and 1.5 parts of OH1 were added. After heating and reducing the pressure to dehydrate, the mixture was stirred at 100°C for 1 hour under a nitrogen stream until homogeneous, to obtain a main component (Breakdown a01) having a polyamine (A) content of 85% and a total active hydrogen content of 95.0 mgKOH / g.

[0054] (Compositions a02 to a15) Base components (compositions a02 to a15) were obtained in the same manner as in the above-described composition a01, except that the types and amounts (units: parts) of each component shown in the middle section of Table 2 were used. In Table 2, the "maximum amine value (mg KOH / g)" refers to the amine value of the polyamine (A) when one type of polyamine (A) is used, and refers to the largest amine value when two or more types of polyamine (A) are used. In addition, the "average amine value (mg KOH / g)" refers to the amine value of the polyamine (A) when one type of polyamine (A) is used, and refers to the average value of the amine values ​​of the two or more types of polyamine (A) when two or more types of polyamine (A) are used.

[0055]

[0056] <Performance Evaluation of Main Agent Component> The prepared main agent components were subjected to the performance evaluation described below. The results are shown in Table 3.

[0057] (Pot Life) The base component and polyisocyanate (trade name "Duranate TSE-100", Asahi Kasei) were mixed in a 1:1 mass ratio and stirred for approximately 1 minute to obtain a uniform mixed solution. The resulting mixed solution was sealed in a sealed container and kept at room temperature (25°C). The sealed container was tilted approximately 90° and left for 1 minute, and the fluidity was determined to have been lost when the liquid level of the mixed solution no longer tilted. The time until fluidity was lost was defined as the pot life. The pot life was evaluated according to the following evaluation criteria. This evaluation assumes the use of a two-component mixing dispenser (static mixer). This dispenser is designed to replace the contents within 1 hour, and if the amount used is large, the contents can be used up in 30 minutes. ◎: Fluidity was maintained for 3 hours or more. ○: Fluidity was maintained for 1 hour or more but less than 3 hours. △: Fluidity was maintained for 30 minutes or more but less than 1 hour. ×: Fluidity was lost immediately after mixing or within 30 minutes.

[0058] (Normal Adhesion) The mixed solution prepared for the evaluation of the "pot life" above was applied to a SUS plate, and a test piece was prepared by bonding two SUS plates together. The prepared test piece was left at room temperature (25°C) for one day, and then the two SUS plates were peeled off with bare hands. The normal adhesion was evaluated according to the following evaluation criteria. If curing had progressed to a certain extent, there was no peeling or interfacial peeling occurred, and the normal adhesion could be evaluated as good. On the other hand, if cohesive failure occurred or the composition was uncured, the desired physical properties were not achieved and the composition was evaluated as unsatisfactory. Note that for formulations a11 and a12, fluidity was lost immediately after formulation, making it impossible to evaluate the normal adhesion and the heat peeling described below. On the other hand, for formulation a10, the pot life was within the measurable range (fluidity was lost in less than 30 minutes), making it possible to evaluate the normal adhesion and the heat peeling described below. ⊚: No peeling occurred. ◯: Interfacial peeling occurred. Δ: Cohesive failure occurred. ×: Unhardened (liquid or syrup-like).

[0059] (Heat Peeling) The test pieces prepared for the evaluation of "normal adhesion" above were heat treated at 80°C for 30 minutes, and the heat peeling (repairability) was evaluated according to the following evaluation criteria: ○: Peeling occurred. ×: No peeling occurred.

[0060]

[0061] <Preparation of Main Agent (1)> The components of the types and amounts (unit: parts) shown in Table 4 were mixed and stirred for 5 minutes using a stirring mixer (product name "Awatori Rentaro", manufactured by Thinky Corporation) to obtain main agents of Blending Examples A01 to A12. The "filling ratio (%)" in Table 4 is the ratio (%) of inorganic filler to the main agent.

[0062]

[0063] <Preparation of Curing Agent (1)> The components shown in Table 5 in the types and amounts (unit: parts) were mixed and stirred for 5 minutes using a stirring mixer (product name "Awatori Rentaro", manufactured by Thinky Corporation) to obtain curing agents of Blending Examples B01 to B12. The "filling ratio (%)" in Table 5 is the ratio (%) of inorganic filler to the curing agent.

[0064]

[0065] <Preparation of Paint (Curable Composition) (1)> Paint (two-component curable composition) to be applied using a two-component mixing dispenser (static mixer) was prepared by combining the base agent and curing agent in the types and amounts (unit: parts) shown in Table 6. The "filling rate (%)" in Table 6 is the proportion (%) of inorganic filler in the entire curable composition (total of base agent and curing agent).

[0066]

[0067] <Evaluation of Paint (Curable Composition) (1)> (Thermal Conductivity) The thermal conductivity of the cured product obtained by curing the paint (curable composition) was measured using the hot disc method (ISO 22007-2). Specifically, the paint was applied to a mold (10 cm x 10 cm) and then pressed at a constant pressure. The coating was then aged at 40°C for 96 hours to obtain a film-like cured product. The thermal conductivity of the resulting cured product (heat dissipating material) was then measured using a thermal property measuring device (product name "TPS2500S", manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The results are shown in Table 7.

[0068] (Pot life) Each paint (combination of base agent and curing agent) was placed in a two-component mixing static mixer and discharged, then left for a predetermined time. The pot life was the time it took for the paint to harden at the tip of the static mixer and become unable to be discharged again. The pot life was then evaluated according to the following evaluation criteria. The results are shown in Table 7. ◎: Usable for 3 hours or more. ○: Usable for 1 hour or more but less than 3 hours. △: Usable for 30 minutes or more but less than 1 hour. ×: Unusable in less than 30 minutes.

[0069] (Normal adhesion) Each paint (combination of base agent and curing agent) was placed in a two-component static mixer. The paint was ejected from the tip of the static mixer and applied to a SUS plate, and a test piece was prepared by bonding two SUS plates together. The prepared test piece was left at room temperature (25°C) for one day, and then the two SUS plates were peeled off with bare hands, and the normal adhesion was evaluated according to the following evaluation criteria. The results are shown in Table 7. ⊚: No peeling occurred. ◯: Interfacial peeling occurred. Δ: Cohesive failure occurred. ×: Uncured (liquid or starch syrup-like).

[0070] (Heat peeling) The test pieces prepared for the evaluation of "normal adhesion" above were heat treated at 80°C and 120°C for 30 minutes, and heat peeling (repairability) was evaluated according to the following evaluation criteria. The results are shown in Table 7. 5 (very good): Interfacial peeling was easy after heating at 80°C for 30 minutes. 4 (good): Interfacial peeling was easy after heating at 120°C for 30 minutes. 3 (normal): Cohesive failure occurred when force was applied after heating at 80°C for 30 minutes. 2 (acceptable): Cohesive failure occurred when force was applied after heating at 120°C for 30 minutes. 1 (fail): No peeling occurred.

[0071]

[0072] <Preparation of Main Agent (2)> Main agents of Blending Examples A13 to A38 were obtained in the same manner as in the above-mentioned "Blending of Main Agent Components" and "Preparation of Main Agent (1)," except that the types and amounts (units: parts) of each component shown in Tables 8-1 and 8-2 were used. The "Filling Rate (%)" in Tables 8-1 and 8-2 is the ratio (%) of inorganic filler to the main agent.

[0073]

[0074]

[0075] <Preparation of Curing Agent (2)> Curing agents of Blending Examples B13 to B38 were obtained in the same manner as in the above-mentioned "Preparation of Curing Agent (1)" except that the types and amounts (units: parts) of each component shown in Tables 9-1 and 9-2 were used. The "Filling ratio (%)" in Tables 9-1 and 9-2 is the ratio (%) of inorganic filler to the curing agent.

[0076]

[0077]

[0078] <Preparation of Paint (Curable Composition) (2)> Paint (two-component curable composition) to be applied using a two-component mixing dispenser (static mixer) was prepared by combining the base agent and curing agent in the types and amounts (unit: parts) shown in Tables 10-1 and 10-2. The "filling rate (%)" in Tables 10-1 and 10-2 is the percentage (%) of inorganic filler in the entire curable composition (total of base agent and curing agent).

[0079] <Evaluation of Paints (Curable Compositions) (2)> In the same manner as in the above-mentioned "Evaluation of Paints (Curable Compositions) (1)," the thermal conductivity of the cured products (heat dissipation materials) was measured, and the usable time, normal adhesion, and heat peelability (repairability) of each paint were evaluated. The results are shown in Tables 10-1 and 10-2.

[0080]

[0081]

[0082] The curable composition of the present invention is useful as a material for forming a heat dissipating material such as a heat dissipating sheet that is disposed between a heat generating body such as an electronic component and a heat dissipating device such as a heat sink.

Claims

1. A two-component curable composition containing a combination of a main agent and a curing agent used for forming a heat dissipation material, wherein the main agent contains a polyamine (A), a polyol (C), and an inorganic filler (D1), the curing agent contains a polyisocyanate (B) and an inorganic filler (D2), in the main agent, the content of the polyamine (A) in the total of the polyamine (A) and the polyol (C) is 50 to 90% by mass, and the value of the ratio (NCO / (NH + OH)) of the number of moles of isocyanate groups (NCO) in the curing agent to the total number of moles of amino groups and hydroxyl groups (NH + OH) in the main agent is 0.75 to 2.

50.

2. The curable composition according to claim 1, wherein the amine value of the polyamine (A) is 300 mgKOH / g or less.

3. The curable composition according to claim 1 or 2, wherein the polyisocyanate (B) is an aliphatic polyisocyanate.

4. The curable composition according to any one of claims 1 to 3, wherein the inorganic filler (D1) and the inorganic filler (D2) are each independently at least one selected from the group consisting of metals, metal oxides, metal nitrides, metal hydroxides, and metal carbonates.

5. The curable composition according to any one of claims 1 to 3, wherein the inorganic filler (D1) and the inorganic filler (D2) are each independently at least one selected from the group consisting of alumina, aluminum nitride, aluminum hydroxide, magnesium oxide, zinc oxide, boron nitride, and magnesium hydroxide.

6. The curable composition according to any one of claims 1 to 5, wherein the filling rate of the inorganic filler (D1) in the main agent is 70 to 95% by mass, and the filling rate of the inorganic filler (D2) in the curing agent is 50 to 95% by mass.

7. A heat dissipation material which is a cured product obtained by curing the curable composition according to any one of claims 1 to 6.

8. The heat dissipation material according to claim 7, having a thermal conductivity of 2.0 W / (m·K) or more.

9. The heat dissipation material according to claim 7 or 8, wherein the total filling rate of the inorganic filler (D1) and the inorganic filler (D2) is 65 to 95% by mass.

10. An article comprising a heating element and the heat dissipation material according to any one of claims 7 to 9, disposed in contact with the heating element.

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