Curable composition and cured product thereof

Abstract

To enable enhancement of a heat dissipation effect by achieving improved thermal conductivity while maintaining shape followability in a cured product.SOLUTION: A curable composition according to an embodiment comprises an epoxy resin, a room-temperature curable polyaddition-type curing agent, a thermally conductive filler, and a core-shell rubber particle, wherein the room-temperature curable polyaddition-type curing agent includes a polyamine curing agent having a weight-average molecular weight of 500 or more and 4000 or less, and the thermally conductive filler is aluminum hydroxide.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a two-component, room-temperature curable curable composition containing an epoxy resin and a room-temperature curable curing agent, and a cured product thereof, and in particular to a curable composition that can improve heat dissipation effects by achieving both high thermal conductivity and shape conformability, and a cured product thereof. [Background technology]

[0002] In recent years, electronic components, electronic devices, precision components, etc. installed in vehicles such as automobiles, personal computers, mobile phones, digital cameras, projectors, optical disk drives, information terminal equipment, etc. have become smaller, more powerful, more dense, more powerful, more functionally integrated, thinner, and lighter, resulting in an increase in the amount of heat generated. When the amount of heat generated by components increases and the temperature around them also rises, the heat can cause the performance of the components, etc. and their surrounding components to deteriorate, malfunction, or even break. For this reason, thermal countermeasures to suppress temperature increases due to heat generation have become extremely important in various devices, etc.

[0003] In particular, in the field of automotive parts, the market for secondary batteries such as lithium-ion batteries (LIBs) is expanding as a power source for hybrid electric vehicles (HEVs), battery-electric vehicles (BEVs), and other electric vehicles (xEVs). However, battery packs using secondary batteries such as lithium-ion batteries installed in vehicles are experiencing increased heat generation during charging and discharging due to the increasing capacity and output of these batteries. Furthermore, the high density of battery cells in a limited space makes it easy for heat to accumulate, resulting in the battery quickly reaching its allowable temperature limit. In particular, lithium-ion batteries have a high energy density, which causes a rapid temperature rise. As temperatures rise, the electrolyte becomes unstable, deteriorating the power-generating elements and potentially reducing battery performance and life. Furthermore, prolonged high-temperature conditions exceeding the limit of operating temperature could result in battery damage. Therefore, there is an urgent need to develop a heat dissipation design that can dissipate heat within the battery pack to maintain stable battery performance and safety.

[0004] Therefore, as a measure to dissipate heat from secondary batteries, attempts have been made to interpose a heat conductive medium between the battery cell and the module case or battery pack housing (for example, a plastic or metal housing), between the battery cell and a heat sink (heat dissipation material), or between the housing and a heat sink, etc., in order to dissipate the heat generated in the battery cell to the housing or heat sink side. For example, Patent Document 1 proposes a two-component curable composition as a curable resin composition used as a thermally conductive adhesive for fixing EV battery cells to a module case, the curable composition comprising a first component containing an epoxy resin and a second component containing an epoxy curing agent, the curable composition further comprising polymer particles having a core-shell structure including a core layer and a shell layer and aluminum hydroxide, the total weight of the aluminum hydroxide being 55 wt % or more and 85 wt % or less relative to 100 wt % of the total weight of the curable composition, and the average particle size of the aluminum hydroxide being 11 μm or more and 200 μm or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2022 / 138807 Summary of the Invention [Problem to be solved by the invention]

[0006] However, Patent Document 1 discloses a technology for improving impact resistance so that the adhesive will not peel off from the substrate even when shear stress is applied due to an external impact such as a vehicle collision, and the formulation described in Patent Document 1 has limitations in terms of enhancing the heat dissipation effect. In other words, battery cells coated with adhesive are prone to deformation due to expansion and contraction during charging and discharging, and deformation varies depending on the type of substrate. If gaps form between the battery cell and the adhesive due to expansion and contraction during charging and discharging, the insulating effect of air hinders the transfer of heat from the battery cell to the housing (such as a module case), reducing heat dissipation efficiency. However, when a large amount of aluminum hydroxide is added to the adhesive formulated as described in Patent Document 1 to increase thermal conductivity, the adhesive's elongation, shear adhesive strength, and shear displacement decrease, reducing its ability to conform to battery cell deformation. Therefore, even if the adhesive's thermal conductivity is increased, its ability to conform to deformation of the heating element decreases. Therefore, when the battery cell deforms due to expansion and contraction during charging and discharging, the efficiency of heat transfer from the battery cell to the adhesive decreases, limiting the extent to which heat can be enhanced.

[0007] Therefore, an object of the present invention is to provide a curable composition that can improve thermal conductivity and enhance heat dissipation effects while ensuring shape conformability in the cured product, and a cured product thereof. [Means for solving the problem]

[0008] The curable composition of the invention of claim 1 is a curable composition containing an epoxy resin, a room temperature curing polyaddition type curing agent, a thermally conductive filler, and core-shell type rubber particles, wherein the polyaddition type curing agent includes a polyamine-based curing agent having a weight average molecular weight (MW) in the range of 500 to 4000, and the thermally conductive filler is aluminum hydroxide.

[0009] The epoxy resin may be a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, an alicyclic epoxy resin, or the like, but preferably a glycidyl ether type epoxy resin such as a bisphenol A type epoxy resin or a bisphenol F type epoxy resin is used. A bisphenol F type epoxy resin is more preferred, as it can increase the elongation of the cured product of the curable composition.

[0010] The room-temperature-curable polyaddition curing agent is a curing agent that causes a three-dimensional crosslinking reaction of an epoxy resin, and undergoes an addition reaction with the epoxy resin at room temperature to crosslink and harden it. Note that room-temperature curing does not strictly require curing within the temperature range of room temperature (23±2°C), i.e., it does not mean that it cannot be cured at temperatures other than room temperature (23±2°C), but rather it is sufficient that it can be cured near room temperature (1 to 30°C) without heating, and is the concept of room-temperature curing. As this room temperature curable polyaddition type curing agent, a polyamine-based curing agent having a weight average molecular weight (MW) in the range of 500 or more and 4000 or less, more preferably 600 or more and 3500 or less, and even more preferably 600 or more and 2000 or less is used. The polyamine-based curing agent includes polyetheramines, polyamidoamines, aliphatic polyamines, alicyclic polyamines, etc., and may be either unmodified or modified polyamines. Aliphatic amines are preferred, and polyetheramines or polyamidoamines are more preferred.

[0011] The thermally conductive filler is an insulating aluminum hydroxide, generally of the gibbsite type (Al(OH)3). The core-shell rubber (CSR) particles are particulate materials having a rubbery core layer and a shell layer covering the rubbery core layer. The materials forming the core layer and shell layer are not particularly limited, as long as the core layer contains a rubber component and the shell layer covering the rubbery core layer is made of a non-elastic polymer material that does not exhibit rubber elasticity. The core layer, the shell layer, or both the core layer and the shell layer may be crosslinked (e.g., ionically or covalently), or the shell layer may be grafted to the core layer. The core-shell rubber particles may be incorporated into an epoxy resin in advance.

[0012] The aluminum hydroxide in the curable composition of the invention of claim 2 is preferably contained in a range of 86% by mass or more and 95% by mass or less, more preferably 87% by mass or more and 95% by mass or less, and even more preferably 87% by mass or more and 90% by mass or less, relative to 100% by mass of the total amount of the curable composition.

[0013] The polyamine-based curing agent having a weight average molecular weight (MW) of 500 or more and 4000 or less in the curable composition of the invention of claim 3 is preferably a polyetheramine or a polyamidoamine, and more preferably has an ether bond or a polyoxyalkylene bond.

[0014] The polyaddition curing agent of the curable composition of the invention of claim 4 is a combination of a polyamine-based curing agent having a weight-average molecular weight (MW) in the range of 500 or more and 4000 or less, preferably 600 or more and 3500 or less, and more preferably 600 or more and 2000 or less, and a polyamine-based curing agent having a weight-average molecular weight (MW) in the range of 100 or more and less than 500, preferably 120 or more and 480 or less, and more preferably 150 or more and 450 or less.

[0015] The core-shell type rubber particles in the curable composition of the invention of claim 5 are preferably blended in a range of 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, and even more preferably 20 to 40 parts by mass, per 100 parts by mass of epoxy resin.

[0016] The core-shell type rubber particles of the curable composition of the invention of claim 6 preferably have a median primary particle diameter measured by a laser diffraction / scattering method in the range of 10 to 1500 nm, more preferably 20 to 1200 nm, and even more preferably 30 to 1000 nm.

[0017] The curable composition of the invention of claim 7 is preferably one in which the thermal conductivity of a cured product obtained by curing the curable composition is in the range of 2.0 W / m·K or more and 5.0 W / m·K or less, more preferably 3.1 W / m·K or more and 4.5 W / m·K or less, and even more preferably 3.3 W / m·K or more and 4.0 W / m·K or less.

[0018] The curable composition of the invention of claim 8 is preferably such that the elongation at break of a dumbbell-shaped No. 6 test piece of the cured product obtained by curing the curable composition in a tensile test in accordance with JIS K6249 is in the range of 1.0% or more and 5.0% or less, more preferably 1.0% or more and 3.0% or less, and even more preferably 1.4% or more and 2.0% or less. The above-mentioned elongation percentage is the elongation percentage (%) when a dumbbell-shaped test piece is punched out using a JIS dumbbell No. 6 from a cured product (2 mm thick) obtained by curing a curable composition at room temperature in accordance with JIS K6249 (2003), and pulled to break at a gauge length of 20 mm, a pulling rate of 1 mm / min, and room temperature.

[0019] The curable composition of the invention of claim 9 is preferably such that the shear adhesive strength of the cured product obtained by curing the curable composition, measured in accordance with JIS K6850, is in the range of 4.0 MPa or more and 8.0 MPa or less, more preferably 5.0 MPa or more and 8.0 MPa or less. The shear adhesive strength was determined in accordance with the tensile shear adhesive strength test method for rigid adherends of JIS K6850 (1999), in which a test piece was prepared by curing a curable composition and bonding two adherends (electrodeposition-coated plates) with the cured product (0.7 mm thick). The test piece was then pulled in the longitudinal direction at room temperature at a pulling rate of 5 mm / min, and the breaking force (N) at the time of break was measured to determine the shear strength (MPa).

[0020] The cured product of the invention of claim 10 is obtained by curing a curable composition containing an epoxy resin, a room-temperature curing polyaddition curing agent, a thermally conductive filler, and core-shell rubber particles, wherein the polyaddition curing agent includes a polyamine-based curing agent having a weight-average molecular weight in the range of 500 to 4000, and the thermally conductive filler is aluminum hydroxide. [Effects of the Invention]

[0021] The curable composition according to the invention of claim 1 contains an epoxy resin, a room temperature curable polyaddition type curing agent having a weight average molecular weight in the range of 500 to 4000, preferably 600 to 3500, and more preferably 600 to 2000, a polyamine-based curing agent, aluminum hydroxide as a thermally conductive filler, and core-shell rubber particles. As a result of extensive experimental research, the inventors discovered that by using a room temperature curing polyaddition type curing agent with a weight average molecular weight in the range of 500 to 4000 as the curing agent for a composition containing an epoxy resin, aluminum hydroxide, and core-shell rubber particles, it is possible to ensure extensibility, shear adhesive strength, and shear displacement without the cured product becoming hard, even when the aluminum hydroxide is highly loaded, and thus completed the present invention.

[0022] Specifically, the curable composition of the present invention, characterized by its high aluminum hydroxide loading, can enhance the thermal conductivity of the cured product. Furthermore, by combining an epoxy resin with a room-temperature-curing polyaddition-type curing agent having a weight-average molecular weight of 500 to 4,000, preferably 600 to 3,500, and more preferably 600 to 2,000, and core-shell rubber particles, the cured product can maintain its extensibility and adhesive strength even at high aluminum hydroxide loadings. Therefore, the cured product can have improved thermal conductivity without sacrificing its shape conformability, achieving both high thermal conductivity and shape conformability. Therefore, the cured product can have enhanced thermal conductivity, and the shape conformability of the cured product allows it to conform to the deformation of the heat dissipation target, reducing contact thermal resistance with the heat dissipation target and effectively conducting heat from the heat dissipation target to the cured product, thereby enhancing the heat dissipation effect.

[0023] According to the curable composition of the invention of claim 2, the aluminum hydroxide is blended in an amount within the range of 86% by mass or more and 95% by mass or less, more preferably 87% by mass or more and 95% by mass or less, and even more preferably 87% by mass or more and 90% by mass or less, relative to 100% by mass of the total amount of the curable composition. Therefore, in addition to the effect of claim 1, it is possible to achieve both ease of application and high thermal conductivity.

[0024] According to the curable composition of the invention of claim 3, the polyamine-based curing agent having a weight-average molecular weight (MW) in the range of 500 or more and 4000 or less is a polyetheramine or a polyamidoamine, and therefore, in addition to the effect of claim 1, it is possible to further increase elongation and adhesive strength and further improve shape conformability. More preferably, if a polyetheramine is used, it is possible to more highly fill aluminum hydroxide, and this is easy to do, thereby improving the workability of producing the composition.

[0025] According to the curable composition of the invention of claim 4, the polyaddition curing agent further contains a polyamine-based curing agent having a weight-average molecular weight of 100 or more and less than 500, more preferably 120 or more and 480 or less, and even more preferably 150 or more and 450 or less, and therefore, in addition to the effect of claim 1, the curing speed can be increased.

[0026] According to the curable composition of the invention of claim 5, the core-shell type rubber particles are blended in an amount of 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, and even more preferably 20 to 40 parts by mass, per 100 parts by mass of epoxy resin. Therefore, in addition to the effect of claim 1, toughness can be ensured without impairing the viscosity characteristics that allow high loading of aluminum hydroxide.

[0027] According to the curable composition of the invention of claim 6, the core-shell type rubber particles have a median primary particle diameter measured by a laser diffraction / scattering method of 10 to 1500 nm, preferably 20 to 1200 nm, and even more preferably 30 to 1000 nm, so that the core-shell type rubber particles have high dispersibility, thereby achieving stable properties of the cured product in addition to the effect of claim 1.

[0028] According to the curable composition of the invention of claim 7, the thermal conductivity of the cured product obtained by curing the curable composition is in the range of 2.0 to 5.0 W / m K, more preferably 3.1 to 4.5 W / m K or less, and even more preferably 3.3 to 4.0 W / m K or less. Therefore, in addition to the effect of claim 1, it is possible to improve heat dissipation properties.

[0029] According to the curable composition of the invention of claim 8, the elongation at break of a dumbbell-shaped No. 6 test piece of the cured product obtained by curing the curable composition in a tensile test according to JIS K6249 is within the range of 1.0 to 5.0%, more preferably 1.0 to 3.0%, and even more preferably 1.4 to 2.0%, so that in addition to the effect of claim 1, it is possible to improve shape conformability.

[0030] According to the curable composition of the invention of claim 9, the shear adhesive strength of the cured product obtained by curing the curable composition, measured in accordance with JIS K6850, is in the range of 4.0 to 8.0 MPa, more preferably 5.0 to 8.0 MPa. Therefore, in addition to the effect of claim 1, it is possible to improve shape conformability.

[0031] According to a tenth aspect of the present invention, there is provided a cured product obtained by curing a curable composition containing an epoxy resin, a room-temperature curing polyaddition curing agent, a thermally conductive filler, and core-shell rubber particles, wherein the polyaddition curing agent comprises a polyamine-based curing agent having a weight-average molecular weight in the range of 500 to 4,000, preferably 600 to 3,500, and more preferably 600 to 2,000, and the thermally conductive filler is aluminum hydroxide. Therefore, the thermal conductivity of the cured product can be increased by a high loading of aluminum hydroxide. Furthermore, by combining the epoxy resin with the room-temperature curing polyaddition curing agent having a weight-average molecular weight in the range of 500 to 4,000, preferably 600 to 3,500, and more preferably 600 to 2,000, and the core-shell rubber particles, the extensibility and adhesive strength of the cured product can be ensured even when the aluminum hydroxide is highly loaded. Therefore, the thermal conductivity can be improved without impairing the shape conformability of the cured product, achieving both high thermal conductivity and shape conformability. Therefore, the thermal conductivity of the cured product can be increased, and by ensuring the shape conformability of the cured product, it can follow the deformation of the heat dissipation object, reducing the contact thermal resistance with the heat dissipation object and effectively conducting heat from the heat dissipation object to the cured product, thereby improving the heat dissipation effect. DETAILED DESCRIPTION OF THE INVENTION

[0032] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described. The curable composition according to an embodiment of the present invention is a two-component room temperature polymerization type (two-component room temperature curing type) curable composition containing an epoxy resin, a polyamine-based curing agent having a specific molecular weight, which is a room temperature curing polyaddition type curing agent for the epoxy resin, aluminum hydroxide, which is a thermally conductive filler, and core-shell rubber particles.

[0033] The epoxy resin may generally be a compound having two or more epoxy groups, and may be any of a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, and an alicyclic epoxy resin.

[0034] Examples of glycidyl ether type epoxy resins include bisphenol type epoxy resins obtained by reacting epichlorohydrin with phenolic compounds such as bisphenol A type, bisphenol F type, bisphenol S type, bisphenol AD ​​type, bisphenol AF type, bisphenol AP type, bisphenol B type, bisphenol BP type, bisphenol C type, bisphenol G type, bisphenol M type, bisphenol P type, brominated bisphenol A type, and hydrogenated bisphenol A type; biphenyl type epoxy resins having a bisphenyl group; and phenol Examples of epoxy resins include novolac epoxy resins obtained by reacting a novolac compound such as a novolac or orthocresol novolac with epichlorohydrin, epoxy compounds obtained by reacting a polyhydric phenol with epichlorohydrin, epoxy compounds obtained by reacting an aliphatic polyhydric alcohol with epichlorohydrin, and epoxy compounds having a tricyclodecane ring (for example, epoxy compounds obtained by a production method in which dicyclopentadiene and a cresol such as m-cresol or a phenol are polymerized, followed by reaction with epichlorohydrin).

[0035] Glycidyl ester type epoxy resins include epoxy compounds of synthetic fatty acids such as dimer acid (dimer acid diglycidyl ester, etc.), and epoxy compounds of phthalic acid (tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, phthalic acid diglycidyl ester), etc. Glycidylamine-type epoxy resins include N,N,N',N'-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N,N-diglycidylamino-1,3-glycidylphenyl ether (DGAGPE), N,N-diglycidylaniline, triglycidyl isocyanate (TGIC), 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and aminophenol types. Alicyclic epoxy resins include 3,4-epoxycyclomethyl(3,4-epoxy)cyclohexanecarboxylate. These epoxy resins may be used alone or in combination of two or more.

[0036] Among these, glycidyl ether epoxy resins, such as bisphenol A epoxy resins and bisphenol F epoxy resins, are preferably used, and bisphenol F epoxy resins, which have low viscosity, are more preferred. Bisphenol F epoxy resins can improve the elongation and flexibility of the resulting cured product, and can conform better to the heat dissipation target, thereby improving the heat dissipation effect.

[0037] Epoxy resins range from liquid to solid depending on the molecular weight. However, from the viewpoint of ease of handling and preparation, low-molecular-weight epoxy resins that are liquid to semi-solid at room temperature are preferred. Epoxy resins that are liquid at room temperature have an epoxy equivalent of, for example, 120 to 450 g / eq, preferably 130 to 400 g / eq, and more preferably 140 to 300 g / eq. The epoxy equivalent refers to the number of grams of resin containing 1 gram equivalent of epoxy groups (unit: g / eq). This epoxy equivalent is a value measured in accordance with JIS K7236:2001. Liquid epoxy resins are preferably those with a viscosity in the range of 500 to 90,000 mPa·s / 25°C, more preferably 800 to 40,000 mPa·s / 25°C, and even more preferably 1,000 to 20,000 mPa·s / 25°C. A viscosity within the above range is easy to handle and allows for easy adjustment of the viscosity to suit application. The epoxy resin may be compounded in the form of an epoxy resin containing core-shell type rubber particles, which will be described later.

[0038] Polyamine-based curing agents, which are room-temperature-curing polyaddition curing agents, are compounds containing active hydrogen groups that can react with epoxy resins at room temperature (1 to 30°C) to form crosslinks, and examples of such compounds include polyetheramines (including polyoxyalkylene polyamines), polyamidoamines, aliphatic polyamines, alicyclic polyamines, aromatic polyamines (which generally react at high temperatures but can be cured at room temperature if an accelerator is used), and modified products thereof. Liquid curing agents are usually used from the standpoint of workability in the production of the composition.

[0039] In the curable composition of this embodiment, as the room-temperature curable polyaddition curing agent, a polyamine-based curing agent having a weight-average molecular weight (MW) of 500 or more and 4000 or less, preferably 600 or more and 3500 or less, and more preferably 600 or more and 2000 or less, is used in combination with a polyamine-based curing agent having a weight-average molecular weight (MW) of 100 or more and less than 500, preferably 120 or more and 480 or less, and more preferably 150 or more and 450 or less, is used in combination. This combination allows for rapid curing, and produces a cured product with high extensibility and adhesive strength even when highly filled with aluminum hydroxide, a thermally conductive filler.

[0040] Polyamine-based curing agents having a weight-average molecular weight in the range of 500 to 4000 are preferably polyetheramines or polyamidoamines. Polyetheramines and polyamidoamines can provide cured products with excellent extensibility and flexibility (softness), even when loaded with a high amount of aluminum hydroxide, a thermally conductive filler, and can further improve shape conformability. Furthermore, they generate less heat when reacted with an epoxy resin, reducing residual stress during the curing process, thereby enhancing adhesive strength. This can further enhance the heat dissipation effect. In particular, polyetheramines can reduce the viscosity of the composition, facilitating high loading of aluminum hydroxide, a thermally conductive filler, and improving workability during composition production. Furthermore, the high loading of aluminum hydroxide can further enhance the thermal conductivity of the cured product.

[0041] The polyetheramines (including polyoxyalkylene polyamines) are preferably amine-terminated polyethers that contain a polyether main chain and have, on average, preferably 1 to 4 (more preferably 1.5 to 3) amino groups and / or imino groups per molecule, and examples thereof include poly(oxypropylene) monoamines, poly(oxypropylene) diamines, poly(oxypropylene) triamines, and poly(oxypropylene) tetraamines. Specific examples include triethylene glycol diamine, tetraethylene glycol diamine, and diethylene glycol bis(propylene glycol). Examples of polyetheramines include diethylene glycol bis(3-aminopropyl) ether, bis(2-aminoethyl) ether, 3,6-dioxaoctane-1,8-diamine, 4,7-dioxadecane-1,10-diamine, 4,7-dioxadecane-2,9-diamine, 4,9-dioxadodecane-1,12-diamine, 5,8-dioxadodecane-3,10-diamine, 4,7,10-trioxatridecane-1,13-diamine, bis(3-aminopropyl)polytetrahydrofuran, polytetrahydrofuran diamine, and alicyclic ether group-containing diamines. Polyetheramines may be primary or secondary amines, with primary amines being preferred.

[0042] Polyamidoamines are polyamide resins having primary and secondary amines in the molecule, and include dehydration condensates produced by a dehydration condensation reaction between dimer acids (polycarboxylic acids, such as oleic acid, elaidic acid, cetoleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, soybean oil fatty acids, tall oil fatty acids, and linseed oil fatty acids) and polyamines (such as aliphatic amines, alicyclic amines, aromatic amines, araliphatic amines, and heterocyclic amines, including polyethylene polyamines such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine), as well as modified products thereof, such as amine adducts with epoxy compounds, Mannich compounds (e.g., Mannich-modified polyamidoamines, phenalkamides, and the like), Michael adducts, and urethane-modified products. These polyamine-based curing agents having a weight average molecular weight in the range of 500 or more and 4000 or less, preferably 600 or more and 3500 or less, and more preferably 600 or more and 2000 or less may be used alone or in combination of two or more kinds.

[0043] Furthermore, polyamine-based curing agents having a weight-average molecular weight in the range of 100 or more and less than 500 are preferably polyetheramines or polyamidoamines. Polyetheramines and polyamidoamines have a fast reaction rate with epoxy resins, shortening the curing time and reducing the viscosity of the composition, facilitating high loading of aluminum hydroxide, a thermally conductive filler, and improving the workability of composition production. Furthermore, higher loading of aluminum hydroxide can further increase the thermal conductivity of the cured product. Furthermore, the amount of heat generated when reacting with epoxy resins is small, reducing residual stress during the curing process, thereby increasing adhesive strength. Polyetheramines are more preferred. The polyamine-based curing agent having a weight-average molecular weight in the range of 100 or more and less than 500, preferably 120 or more and 480 or less, more preferably 150 or more and 450 or less, may be used alone or in combination of two or more.

[0044] Such polyamine curing agents are blended such that the ratio of their active hydrogen equivalent to the epoxy equivalent of the epoxy resin, i.e., active hydrogen equivalent / epoxy equivalent, is preferably within the range of 1.00 / 0.80 to 1.00 / 1.20, more preferably 1.00 / 0.90 to 1.00 / 1.10, and even more preferably 1.00 / 0.95 to 1.00 / 1.05. Furthermore, for 100 parts by mass of the epoxy resin, the amount of the polyamine curing agent is, for example, within the range of 15 parts by mass to 300 parts by mass, preferably 20 parts by mass to 280 parts by mass, more preferably 30 parts by mass to 260 parts by mass, and even more preferably 40 parts by mass to 240 parts by mass. Within this range, the curable composition can be rapidly cured, and the resulting cured product can have good adhesive strength and extensibility. The active hydrogen equivalent (g / eq) is the number of grams of an amine compound containing one equivalent of active hydrogen of an amino group, and is the value obtained by dividing the molecular weight of the amine compound by the number of active hydrogen of amino groups in one molecule of the amine compound.

[0045] The compounding ratio of a high-molecular-weight polyamine curing agent having a weight-average molecular weight (MW) in the range of 500 or more and 4000 or less to a low-molecular-weight polyamine curing agent having a weight-average molecular weight in the range of 100 or more and less than 500 is preferably high-molecular-weight polyamine curing agent / low-molecular-weight polyamine curing agent = 1 / 2 to 1 / 30, more preferably 1 / 3 to 1 / 25. Within this range, quick drying, extensibility, and adhesive strength can be achieved simultaneously without impairing workability.

[0046] When carrying out the present invention, a curing catalyst (also called a polymerization catalyst, curing accelerator, or co-curing agent) which is a catalytic curing agent that releases the strain energy of epoxy groups by a cationic or anionic mechanism to addi- tionally polymerize and crosslink the epoxy groups may be blended to accelerate curing. The curing catalyst may be blended in the main component containing the epoxy resin, or in the curing agent component. Examples of curing catalysts that can be used include tertiary amines (tertiary amines, tertiary amine salts), imidazoles, phosphines (phosphine, phosphonium salts), alcohols, phenols, carboxylic acids, etc. Tertiary amines can promote curing by converting the epoxy groups of the epoxy resin into alkoxide groups that react with other epoxy groups, or by converting some of the epoxy groups into alcohols that add to other epoxy groups.

[0047] Core-shell rubber particles (CSR particles) are particles having a structure with at least two layers: a rubber core layer and a shell layer. The core layer of a core-shell rubber particle (hereinafter sometimes simply referred to as "CSR") refers to the inner part of the CSR, and is capable of forming an internal domain of the CSR, in which a rubbery polymer is arranged. This core layer may be made of any rubbery substance, and is typically a crosslinked rubber, i.e., an elastomer, whose main component is butadiene, acrylic, silicone, or the like. For example, it is preferably made of a polymer obtained by polymerizing a conjugated diene and / or a lower alkyl acrylate, a copolymer obtained by copolymerizing these with a copolymerizable monomer, or a polysiloxane rubber, and further preferably is insoluble in epoxy resin.

[0048] Examples of conjugated dienes include butadiene (e.g., 1,3-butadiene, 2-chloro-1,3-butadiene, 2-methyl-1,3-butadiene, etc.), isoprene, chloroprene, etc., and among these, butadiene is particularly preferred because it is inexpensively available, the resulting polymer has good rubber properties, and is easy to polymerize. Examples of lower alkyl acrylates include ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate. Among these, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred because the resulting polymers have good rubber properties and are easy to polymerize. Examples of monomers copolymerizable with conjugated dienes or alkyl acrylates include aromatic vinyls and aromatic vinylidenes such as styrene, vinyl toluene, vinyl naphthalene, monochlorostyrene, dichlorostyrene, and α-methylstyrene; vinyl cyanides and vinylidene cyanides such as acrylonitrile and methacrylonitrile; alkyl methacrylates such as methyl methacrylate, butyl methacrylate, ethyl (meth)acrylate, and butyl methacrylate; aromatic (meth)acrylates such as benzyl (meth)acrylate and phenoxyethyl acrylate; alkenes such as ethylene, propylene, butylene, and isobutylene; and vinyl halides such as vinyl acetate, vinyl chloride, vinyl bromide, and chloroprene.

[0049] It is also possible to copolymerize monomers having functional groups such as epoxy groups, carboxyl groups, hydroxyl groups, amino groups, etc. For example, examples of monomers having epoxy groups include glycidyl methacrylate, examples of monomers having carboxyl groups include methacrylic acid, acrylic acid, maleic acid, itaconic acid, etc., and examples of monomers having hydroxyl groups include 2-hydroxymethacrylate, 2-hydroxyacrylate, etc.

[0050] Furthermore, as components constituting the core, crosslinkable monomers (polyfunctional monomers) such as divinylbenzene, butanediol di(meth)acrylate, triallyl (iso)cyanurate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, allyl (meth)acrylate, diallyl itaconate, and diallyl phthalate, as well as grafting monomers having two or more unsaturated sites with unequal reactivity, at least one of which is non-conjugated, such as diallyl maleate, monoallyl fumarate, and allyl methacrylate, can be used. When such crosslinkable monomers or grafting monomers are used in small amounts, preferably 10% by mass or less of the total core-shell rubber particles, interlayer bonding is achieved, making the particles less susceptible to deformation even when heated. Furthermore, silicone rubber can also be used as a monomer copolymerizable with conjugated dienes or alkyl acrylates. In addition, instead of or in combination with such a monomer copolymerizable with a conjugated diene or alkyl acrylate, a polysiloxane rubber composed of alkyl- or allyl-disubstituted silyloxy units such as dimethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy, etc. When using such a polysiloxane rubber, it is preferable to introduce a crosslinked structure into the polysiloxane in advance, as necessary, by using a polyfunctional alkoxysilane compound in combination during polymerization or by subjecting a silane compound having a vinyl-reactive group to a radical reaction.

[0051] On the other hand, the shell layer is formed on the outer portion of the core, usually forming the outermost part of the CSR, and has affinity (compatibility) with epoxy resins. The material constituting this shell layer is not particularly limited as long as it does not exhibit rubber elasticity. However, for example, an acrylic copolymer, specifically a polymer obtained by polymerizing an aromatic vinyl monomer, a vinyl cyan monomer, a (meth)acrylate and / or a styrene monomer, or a copolymer obtained by copolymerizing these with a copolymerizable monomer, is preferred. These materials are inexpensive, and can provide both good graft polymerization properties and affinity with epoxy resins, resulting in good adhesive strength over a wide temperature range. Among these, acrylic copolymers with good compatibility with epoxy resins are preferred.

[0052] Examples of monomers copolymerizable with (meth)acrylate or styrene include alkyl acrylates such as ethyl acrylate and butyl acrylate, alkyl methacrylates such as ethyl methacrylate and butyl methacrylate, aromatic vinyls such as vinyl toluene, α-methylstyrene, monochlorostyrene, 3,4-dichlorostyrene and bromostyrene, aromatic vinylidenes, vinyl cyanides such as vinyl acetate, vinyl chloride, acrylonitrile and methacrylonitrile, and vinyl polymerizable monomers such as vinyl cyanide, etc. Among these, ethyl acrylate or acrylonitrile is preferred. Furthermore, by copolymerizing a monomer having an epoxy group and / or a functional group reactive with an epoxy group, such as a carboxyl group, a hydroxyl group, or an amino group, as a monomer copolymerizable with (meth)acrylate or styrene, the surface of the shell layer can be modified with an epoxy group and / or a functional group reactive with an epoxy group. For example, an example of a monomer having an epoxy group is glycidyl methacrylate, an example of a monomer having a carboxyl group is methacrylic acid, acrylic acid, maleic acid, itaconic acid, and an example of a monomer having a hydroxyl group is 2-hydroxymethacrylate, 2-hydroxyacrylate, and the like.

[0053] Furthermore, the shell layer is preferably grafted and / or crosslinked to the core layer, and a crosslinking monomer or grafting monomer can be used in an amount of 10% by mass or less as a monomer copolymerizable with (meth)acrylate or styrene. This is because interlayer bonding is achieved and the particles are less likely to deform even when heated. Examples of the crosslinking monomer include aromatic divinyl compounds such as divinylbenzene, and alkane polyol polyacrylates such as hexanediol diacrylate, butylene glycol dimethacrylate, and norbornene dimethylol dimethacrylate. Examples of the grafting monomer include unsaturated carboxylic acid allyl esters such as allyl methacrylate. The core / shell ratio (weight ratio) of CSR is preferably in the range of 50 / 50 to 95 / 5, and more preferably in the range of 60 / 40 to 90 / 10. If the core / shell ratio (weight ratio) exceeds 50 / 50 and the ratio of the core layer decreases, the viscosity of the composition may decrease, while if the ratio of the shell layer decreases beyond 95 / 5, dispersibility may decrease and stable physical properties may not be obtained.

[0054] There are no particular restrictions on the manufacturing method of such CSR, and commercially available products can be used. CSR may be added in powder form, but a masterbatch form in which CSR is blended and dispersed in epoxy resin (for example, at a concentration of 10 to 60 wt%, preferably 25 to 40 wt%) is preferred.

[0055] The amount of core-shell rubber particles is preferably 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, and even more preferably 20 to 40 parts by mass, per 100 parts by mass of epoxy resin. If the amount of core-shell rubber particles is too high, dispersibility and viscosity decrease, impairing mixing and application workability, reducing the filling ability of aluminum hydroxide, and reducing the properties of the epoxy resin. On the other hand, if the amount is too low, the flexibility and toughness of the cured product cannot be ensured, and the adhesive strength decreases. If the amount is within the above range, the toughness of the cured product can be increased while ensuring application workability.

[0056] Furthermore, the core-shell type rubber particles have a median diameter (average primary particle diameter) of primary particles measured by a laser diffraction / scattering method, which is preferably in the range of 10 to 1500 nm, more preferably 20 to 1200 nm, and even more preferably 30 to 1000 nm. If the median diameter is too small, industrial productivity will be poor and the particles will aggregate, increasing viscosity and reducing handleability and application workability. If the average particle diameter is too large, the effect of toughening the cured product will not be obtained. Furthermore, the surface smoothness of the cured product will decrease, reducing adhesion to the heat dissipation object and reducing adhesive strength. If the diameter is within the above range, the toughness of the cured product can be improved without impairing application workability, adhesive strength, etc.

[0057] According to the definition of terms in the text and explanation of JIS Z 8901 "Test Powders and Test Particles," the median diameter is the particle diameter (diameter) when the number (or mass) of particles larger than a certain particle diameter accounts for 50% of the total powder in the particle size distribution of the powder, that is, the particle diameter of 50% oversize, and is usually called the median diameter or 50% particle diameter. 50 By definition, the size of a particle group is expressed by the average particle size and median size, but here, the values ​​are those displayed in the product description and measured by laser diffraction / scattering method. The median diameter measured by the laser diffraction / scattering method is the particle diameter (D ) at which the cumulative mass fraction is 50% in the particle size distribution obtained by the laser diffraction / scattering method using a laser diffraction particle size distribution analyzer. 50 ) The above numerical values ​​are approximate and not strict, and are naturally approximate values ​​that include errors due to measurement, etc., and do not deny errors of several tens of percent. From the viewpoint of this error, the difference from the average particle size is also small, and the average particle size is approximately equal to the median size, and it can also be considered that the average particle size = the median size.

[0058] The incorporation of these core-shell rubber particles imparts flexibility and toughness to the cured epoxy resin, making it possible to alleviate stresses generated by cure shrinkage during curing and stresses caused by differences in the thermal expansion coefficients at the interface between the adhesive and the adherend, thereby increasing adhesive strength.

[0059] Aluminum hydroxide, a thermally conductive filler, is electrically insulating and has excellent thermal conductivity and flame retardancy among thermally conductive fillers. It is also easily highly filled and highly dispersed in compositions containing epoxy resin, a polyamine-based curing agent having the above-mentioned specific molecular weight, and core-shell rubber particles. Aluminum hydroxide is a white powder crystal usually represented by the chemical formula Al(OH)3 or Al2O3·3H2O, and is generally produced using the Bayer process using bauxite as the raw material.

[0060] The aluminum hydroxide serving as the thermally conductive filler preferably has a median diameter (≒ average particle diameter) measured by a laser diffraction / scattering method within the range of 1 to 200 μm, more preferably 5 to 100 μm, and even more preferably 10 to 50 μm. If the particle diameter of the aluminum hydroxide is too small, aggregation is likely to occur, resulting in a lack of uniform dispersion, and the viscosity increases, resulting in reduced application workability, handling, and filling properties. On the other hand, if the particle diameter is too large, filling and dispersibility decrease, and thermal conductivity decreases. Furthermore, the surface smoothness of the cured product decreases, resulting in reduced adhesion to the heat dissipation target and reduced adhesive strength. If the particle diameter is within the above range, the thermal conductivity of the cured product can be improved without impairing application workability, adhesive strength, etc.

[0061] The content of aluminum hydroxide as the thermally conductive filler is preferably 86% by mass or more and 95% by mass or less relative to 100% by mass of the total mass of the curable composition. According to the curable composition of this embodiment, by blending an epoxy resin, a polyamine-based curing agent having a weight-average molecular weight in the range of 500 to 4000, and core-shell rubber particles, the extensibility and adhesive strength of the cured product can be ensured favorably even with a high aluminum hydroxide loading of 86% by mass or more, and the thermal conductivity of the cured product can be increased by including 86% by mass or more of aluminum hydroxide. On the other hand, if the loading of aluminum hydroxide is too high, the aluminum hydroxide powder or particles will not disperse in the liquid component such as the resin, impairing the workability of mixing and dispersion and the workability of application. Therefore, the upper limit of the aluminum hydroxide loading is preferably 95% by mass or less, and more preferably 90% by mass or less.

[0062] The amount of aluminum hydroxide blended per 100 parts by mass of epoxy resin is preferably within the range of 1200 to 2000 parts by mass, more preferably 1300 to 1800 parts by mass, and even more preferably 1400 to 1700 parts by mass. Within the above ranges, the dispersibility of aluminum hydroxide powder or particles is good, ensuring ease of mixing and dispersion and coating workability, and also enabling high thermal conductivity.

[0063] The incorporation of aluminum hydroxide as a thermally conductive filler can increase the thermal conductivity of the cured product and also impart flame retardancy.

[0064] The curable composition of the present embodiment may further contain a dispersant such as a wetting dispersant, a surface treatment agent, a surfactant, a coupling agent, or the like, in order to improve the dispersibility and dispersion stability of the aluminum hydroxide that is the thermally conductive filler. When carrying out the present invention, diluents, viscosity reducers, plasticizers, strengthening agents, antioxidants, deactivators, solvents, etc. may be blended as needed.

[0065] The curable composition of the present embodiment contains the above-mentioned epoxy resin, a polyamine-based curing agent having a weight-average molecular weight (MW) of 500 or more and 4000 or less, which is a room-temperature curable polyaddition curing agent for the epoxy resin, and a polyamine-based curing agent having a weight-average molecular weight (MW) of 100 or more and less than 500, aluminum hydroxide as a thermally conductive filler, and core-shell rubber particles. The curable composition is produced by mixing and stirring these components homogeneously using a known mixer / disperser, mixer / stirrer, or kneader, such as a Banbury mixer, planetary mixer, Henschel mixer, butterfly mixer, static mixer, super mixer, dynamic mixer, or spiral mixer, a disperser, a dissolver, a homogenizer, a V-type intermixer blender, a mechanochemical device, a tumbler, a plastomill, a kneader, a bead mill, a grain mill, or a roll mill.

[0066] The prepared curable composition of the present embodiment is in a paste or liquid form and is applied to the substrate by known methods, such as a dispenser using a pump, a spray gun, or a brush. The paste or liquid curable composition applied to the substrate is a room-temperature curable composition due to the incorporation of a room-temperature curing polyaddition curing agent, and cures at room temperature to form a cured product. This composition can also be considered a two-part mixture of a base component containing an epoxy resin and a curing agent component. It cures even in a moisture-free environment, making it less susceptible to curing inhibition and suitable for large-area applications. Furthermore, heat dissipation and thermal conduction materials formed by applying and curing a paste or liquid curable composition conform to the fine irregularities on the surface of the substrate (substrate) and adhere to the adhesion interface, reducing contact thermal resistance at the interface and making them less likely to peel.

[0067] In particular, according to the curable composition of the present embodiment, by containing an epoxy resin, a polyamine-based curing agent having a weight-average molecular weight (MW) in the range of 500 to 4000, and core-shell rubber particles, even when the thermally conductive filler, aluminum hydroxide, is highly filled, preferably at 86% by mass or more and 95% by mass, more preferably at 87% by mass or more and 95% by mass or less, and even more preferably at 87% by mass or more and 90% by mass or less, the cured coating film has high elongation, shear adhesive strength, and shear displacement, and thus extensibility and adhesive strength can be ensured. Therefore, high thermal conductivity is achieved through the high filling of aluminum hydroxide, and the extensibility and adhesive strength are ensured by the inclusion of epoxy resin, a polyamine-based curing agent with a weight-average molecular weight in the range of 500 to 4000, and core-shell rubber particles, resulting in shape-following ability in response to deformations in the heat dissipation object.

[0068] Therefore, it is suitable as a heat dissipation material or a heat conduction material for battery cells such as lithium ion batteries, which are prone to deformation due to expansion and contraction during charging and discharging. Furthermore, by containing an epoxy resin and a curing agent, it also functions as an adhesive. Therefore, for example, by interposing it between a battery cell in a cell stack of a secondary battery such as a lithium ion battery and a battery module housing or a battery pack housing, the battery cell and the housing are adhered together, and the heat from the battery cell, which is the heat dissipation target, is dissipated to the housing side.

[0069] That is, when the curable composition is applied to either the battery cell side or the housing side, usually the housing side, and the two are bonded together, the room temperature curing agent causes the curable composition to harden even at room temperature (room temperature), bonding the battery cell and housing together. In this case, in the curable composition of the present embodiment, a polyamine-based curing agent having a weight-average molecular weight (MW) of 100 or more and less than 500 is used in combination with a polyamine-based curing agent having a weight-average molecular weight (MW) of 500 or more and 4000 or less as a room-temperature curing polyaddition curing agent. As a result, the polyamine-based curing agent having a weight-average molecular weight (MW) of 100 or more and less than 500 ensures fast curing properties, and the composition cures in a short time.

[0070] The cured product contains aluminum hydroxide as a highly-filled thermally conductive filler, which provides high thermal conductivity, and the epoxy resin, polyamine-based curing agent with a weight-average molecular weight (MW) in the range of 500 to 4000, and core-shell rubber particles ensure extensibility and adhesive strength. In addition, the incorporation of a polyamine-based curing agent imparts extensibility and flexibility, and in particular, the use of a polyamine-based curing agent reduces the amount of heat generated during the curing process. Furthermore, the incorporation of core-shell rubber particles also imparts flexibility and toughness, making it possible to alleviate stresses generated by cure shrinkage during curing and stresses due to differences in the thermal expansion coefficient at the interface with the adherend, thereby reducing residual stress during curing. Additionally, the incorporation of a polyamine-based curing agent contributes to adhesion to substrates such as metals, due to the unpaired electrons of the amine in the cured product. Therefore, adhesive strength is also ensured.

[0071] Therefore, because it has extensibility and adhesive strength, it can follow the deformation of a heat-generating body (including a heat storage body) such as a battery cell or a heat source, even when the heat source or a heat source expands or contracts due to heat generation or cooling of the battery cell or the heat source, and can adhere closely to the heat-generating body or heat source. As a result, gaps are less likely to form between the heat-generating body or heat source such as a battery cell, and contact thermal resistance can be reduced, allowing the heat from the battery cell to be quickly and efficiently conducted to the cured product, resulting in a high heat dissipation effect. In particular, because it has extensibility and high adhesive strength, it can conform to shapes, and therefore a high heat dissipation effect can be achieved even when applied to uneven parts.

[0072] Furthermore, by applying the curable composition between the battery cells and the casing of the cell stack, the curable composition can easily penetrate between adjacent battery cells. Therefore, even if some of the battery cells in the cell stack generate abnormal heat, the high heat is dissipated to the casing side, preventing it from being conducted to neighboring battery cells, preventing temperature variations between the cells and preventing the temperature inside the entire battery pack from rising.

[0073] Furthermore, since the thermally conductive filler is aluminum hydroxide, which has insulating properties, it is effective in providing electrical insulation around the battery module, is suitable for electronic components that require insulation, and is also flame-retardant. In addition, since it is a room temperature curing type rather than a heat curing type, heating energy can be omitted, allowing for energy-saving bonding, and it is also suitable for application to areas that cannot be heated.

[0074] [Example] Next, examples of the curable composition according to the embodiment of the present invention will be described. The curable composition of this example comprises a liquid epoxy resin in which core-shell rubber particles are dispersed (Kaneka Corporation's product name "Kane Ace (registered trademark) MX-136"; core rubber component of the core-shell rubber particles: polybutadiene (crosslinked butadiene rubber); shell component of the core-shell rubber particles: acrylic copolymer; blending amount of the core-shell rubber particles: 25% by mass; median diameter of primary particles of the core-shell rubber particles (average primary particle diameter): 100 nm; epoxy resin: bisphenol F epoxy resin; epoxy equivalent: 226 g / eq; liquid masterbatch type), a polyamine-based curing agent which is a room-temperature curing polyaddition-type curing agent, aluminum hydroxide (Sumitomo Chemical Co., Ltd.'s product name "CW-325LV"; median diameter: 21 μm) which is a thermally conductive filler, a tertiary amine (ADEKA Corporation's product name "ADEKA Hardener EHC-30") which is a curing catalyst (curing accelerator), and a wetting and dispersing agent (BYK Company's product name "BYK-W"). 903") and a surface treatment agent (product name "KBM-3103C (decyltrimethoxysilane)" from Shin-Etsu Chemical Co., Ltd.). In this example, these materials were mixed at room temperature using a universal mixer until uniform, yielding a paste-like curable composition. The curable composition of this example is a mixture of at least two components (two-component system) consisting of a liquid epoxy resin with dispersed core-shell rubber particles as the main component and a polyamine-based curing agent as the curing agent component, and is cured at room temperature (room temperature), and can be said to be a two-component mixed reaction type (two-component room temperature curing type).

[0075] In this example, a polyamine curing agent having a weight average molecular weight (MW) of 500 or more and 4000 or less and a polyamine curing agent having a weight average molecular weight (MW) of 100 or more and less than 500 are used in combination. In Examples 1 to 3, polyetheramines are used for both the polyamine curing agent having a weight average molecular weight (MW) of 500 or more and 4000 or less and the polyamine curing agent having a weight average molecular weight (MW) of 100 or more and less than 500. In Example 4, polyamidoamines are used as the polyamine curing agent having a weight average molecular weight (MW) of 500 or more and 4000 or less, and polyetheramines are used as the polyamine curing agent having a weight average molecular weight (MW) of 100 or more and less than 500.

[0076] Specifically, in Example 1, a polyoxypropylene diamine (trade name "JEFFAMINE (registered trademark) D-400" manufactured by Hunstman; active hydrogen equivalent: 115 g / eq) having a weight average molecular weight of 430 and represented by the following general formula (1) (in formula (1), x = 6.1 or less) and a polyetheramine (trade name "JEFFAMINE (registered trademark) ED-600" manufactured by Hunstman; active hydrogen equivalent: 132 g / eq) having a weight average molecular weight of 600 and represented by the following general formula (2) (in formula (2), y = 9.0 or less, x + z = 3.6 or less) were used.

[0077] In Example 2, a polyoxypropylenediamine (manufactured by Hunstman, "JEFFAMINE (registered trademark) D-400"; active hydrogen equivalent: 115 g / eq) having a weight average molecular weight of 430 and represented by the following general formula (1) (in formula (1), x = 6.1 or less) and a polyetheramine (manufactured by Hunstman, "JEFFAMINE (registered trademark) ED-900"; active hydrogen equivalent: 250 g / eq) having a weight average molecular weight of 900 and represented by the following general formula (2) (in formula (2), y = 12.5 or less, x + z = 6.0 or less) were used.

[0078] In Example 3, a polyoxypropylene diamine having a weight average molecular weight of 430 ("JEFFAMINE (registered trademark) D-400" manufactured by Hunstman; active hydrogen equivalent: 115 g / eq) represented by the following general formula (1) (where x = 6.1 or less) and a polyoxypropylene diamine having a weight average molecular weight of 2000 ("JEFFAMINE (registered trademark) D-2000" manufactured by Hunstman; active hydrogen equivalent: 514 g / eq) represented by the following general formula (1) (where x = 33 or less) were used.

[0079] In Example 4, polyoxypropylene diamine (JEFFAMINE® D-400 manufactured by Hunstman; active hydrogen equivalent: 115 g / eq) having a weight-average molecular weight of 430 and represented by the following general formula (1) (where x = 6.1 or less) and polyamidoamine (ANCAMIDE® 910 manufactured by EVONIC; active hydrogen equivalent: 230 g / eq) obtained by modifying (dehydration condensation) diethylene glycol diaminopropyl ether with dimer acid were used. The weight-average molecular weight of the polyamidoamine was determined to be approximately 800 to 1000 based on the active hydrogen equivalent of the polyamidoamine.

[0080] [ka]

[0081] [ka]

[0082] For comparison, a curable composition according to a comparative example was also prepared, which contained the same materials as those used in the above-described examples, except that the polyamine-based curing agent used in the comparative example was different. In Comparative Examples 1 to 3, which correspond to the prior art, only polyoxypropylenediamine ("JEFFAMINE (registered trademark) D-400" manufactured by Hunstman; active hydrogen equivalent: 115 g / eq) having a weight average molecular weight of 430 and represented by the above general formula (1) (where x = 6.1 or less) was used as the amine curing agent.

[0083] In Comparative Example 4, the polyamine-based curing agents used were polyoxypropylene diamine having a weight average molecular weight of 430 and represented by the above general formula (1) (where x = 6.1 or less) (Hunstman's "JEFFAMINE (registered trademark) D-400"; active hydrogen equivalent: 115 g / eq), and polyoxypropylene diamine having a weight average molecular weight of 230 and represented by the above general formula (1) (where x = 2.5 or less) (Hunstman's "JEFFAMINE (registered trademark) D-230"; active hydrogen equivalent: 60 g / eq).

[0084] In Comparative Example 5, the polyamine-based curing agents used were polyoxypropylene diamine (Hunstman's "JEFFAMINE (registered trademark) D-400"; active hydrogen equivalent: 115 g / eq) having a weight average molecular weight of 430 and represented by the above general formula (1) (in formula (1), x = 6.1 or less), and trimethylolpropane poly(oxypropylene) triamine (Hunstman's "JEFFAMINE (registered trademark) T-403"; active hydrogen equivalent: 81 g / eq) having a weight average molecular weight of 440 and represented by the following general formula (3) (in formula (3), R = C2H5, n = 1, x + y + z = 5-6).

[0085] In Comparative Example 6, the polyamine-based curing agents used were polyoxypropylene diamine (Hunstman's "JEFFAMINE (registered trademark) D-400"; active hydrogen equivalent: 115 g / eq) having a weight-average molecular weight of 430 and represented by the above general formula (1) (in formula (1), x = 6.1 or less), and glyceryl poly(oxypropylene) triamine (Hunstman's "JEFFAMINE (registered trademark) T-5000"; active hydrogen equivalent: 952 g / eq) having a weight-average molecular weight of 5000 and represented by the following general formula (3) (in formula (3), R = H, n = 0, x + y + z = 85).

[0086] [ka]

[0087] The blending compositions (blended materials, blending amounts) of Examples 1 to 4 and Comparative Examples 1 to 6 are shown in the upper part of Table 1. The units of the numerical values ​​of the blending compositions (blended amounts) shown in the upper part of Table 1 are mass (g). It is clear from the theoretical specific gravity that aluminum hydroxide is filled into the curable composition without being separated.

[0088] [Table 1]

[0089] The curable compositions of Examples 1 to 4 and Comparative Examples 1 to 6 were evaluated for thermal conductivity, shear adhesive strength, shear displacement, and elongation of the cured products.

[0090] The thermal conductivity was measured by placing the curable composition in a predetermined substrate (a mold of 40 mm × 40 mm × 2 mm height), leaving it to harden at room temperature (approximately 20 to 25°C) for 24 hours, and then heating and hardening it at 80°C for 3 hours to shorten the hardening time.The thermal conductivity of the hardened product was measured using a heat flow meter method (steady method) in accordance with ASTM EI530. If the thermal conductivity of the cured product was 2.00 W / m·K or higher, it was judged to have high thermal conductivity and was rated as ◯ (pass), and if it was less than 2.00 W / m·K, it was rated as × (fail).

[0091] The shear adhesive strength was measured in accordance with the tensile shear adhesive strength test method for rigid adherends of JIS K6850 (1999). Specifically, two 25 mm × 100 mm × 1 mm substrates (electrodeposition-coated panels) were prepared as test panels for the adherends. A 0.7 mm thick curable composition was applied to one of the test panels over a 10 mm length from one end of the longitudinal direction. The other test panel was then placed on the coated surface in a linear fashion (curable composition layer between the joints of the two panels: 25 mm × 25 mm × 0.7 mm thick). The curable composition was then allowed to stand at room temperature (approximately 20-25°C) for 24 hours to cure, and then heated at 80°C for 3 hours to shorten the curing time. A test specimen was then prepared in which the two test panels were bonded together by the cured product. Both ends of this test specimen were pulled longitudinally at room temperature (approximately 20-25°C) at a pulling rate of 5 mm / min using a tensile tester (Shimadzu Corporation), and the breaking force (N) at break was measured. The breaking force (N) at this time is expressed as the shear area (mm 2 ) to obtain the shear strength (MPa). If the shear adhesive strength (shear strength) of the cured product was 4.00 MPa or more, it was judged to be good and rated as ◯ (pass), and if it was less than 4.00 MPa, it was rated as × (fail).

[0092] Furthermore, in the tensile shear adhesive strength test method for rigid adherends of the above-mentioned JIS K6850 (1999), both ends of the test piece were pulled in the longitudinal direction at a pulling rate of 5 mm / min at room temperature (approximately 20 to 25°C) using a tensile tester (manufactured by Shimadzu Corporation), and the longitudinal displacement of the adherend at break was measured as the shear displacement (mm) of the cured product. If the shear displacement of the cured product was 0.70 mm or more, it was judged to be good and rated as ◯ (pass), and if it was less than 0.70 mm, it was rated as × (fail).

[0093] The elongation was measured according to JIS K6249 (2003). The curable composition was applied to a specified substrate (made of Teflon®) to a thickness of 2 mm, allowed to stand at room temperature (approximately 20-25°C) for 24 hours to cure, and then heated to 80°C for 3 hours to shorten the curing time. The cured product was punched out using a JIS No. 6 dumbbell to obtain a dumbbell-shaped test specimen. Two gauge lines (gauge distance = 20 mm) were marked at predetermined positions on the dumbbell. The test specimen was then stretched at room temperature (approximately 20-25°C) at a tension rate of 1 mm / min using a tensile tester (manufactured by Shimabara Corporation) until breakage. The gauge distance (gage distance) before tensioning and the gauge distance (gage distance) at breakage were measured, and the maximum elongation at break (%) (= (gauge distance at break - gauge distance before tensioning) / gauge distance before tensioning × 100) was calculated. This elongation rate is the ratio of the gauge length (chuck distance) before tension to the chuck distance when the specimen breaks in the tensile test, and it can be said that the greater the elongation rate, the greater the elongation until fracture. An elongation rate of 1.00% or more was judged to be good and was evaluated as ◯ (pass), and one less than 1.00% was evaluated as × (fail). The results of the measurements and evaluations of the thermal conductivity, shear adhesive strength, shear displacement, and elongation are shown in the lower part of Table 1.

[0094] As shown in Table 1, in Comparative Example 1, the adhesive shear strength, shear displacement, and elongation were all rated as ◯, but the thermal conductivity was rated as x due to the low filling rate of aluminum hydroxide. In Comparative Examples 2 to 6, the filling rate of aluminum hydroxide was increased compared to Comparative Example 1, resulting in improved thermal conductivity and an ◯ rating, but the adhesive shear strength and shear displacement were also rated as ◯, but the elongation was rated x.

[0095] That is, a comparison of Comparative Examples 1 to 3, which correspond to conventional technology and use only polyoxypropylenediamine, a polyetheramine with a weight-average molecular weight of 430, as the polyamine curing agent, reveals that although increasing the aluminum hydroxide filling rate increases the thermal conductivity of the cured product, as the aluminum hydroxide filling rate increases, the elongation, shear adhesive strength, and shear displacement of the cured product decrease. Furthermore, in Comparative Example 4, in which polyoxypropylene diamine, a polyetheramine with a weight-average molecular weight of 430, and polyoxypropylene diamine, a polyetheramine with a weight-average molecular weight of 230, are used in combination as polyamine curing agents, and in Comparative Example 5, in which polyoxypropylene diamine, a polyetheramine with a weight-average molecular weight of 430, and trimethylolpropane poly(oxypropylene) triamine, a polyetheramine with a weight-average molecular weight of 440, are used in combination as polyamine curing agents, the filling rate of aluminum hydroxide is high, so the thermal conductivity of the cured product is high, but the elongation of the cured product is poor. Furthermore, in Comparative Example 6, which uses a combination of polyoxypropylene diamine, a polyetheramine with a weight-average molecular weight of 430, and glyceryl poly(oxypropylene) triamine, a polyetheramine with a weight-average molecular weight of 5000, as the polyamine curing agent, the filling rate of aluminum hydroxide is high, so the thermal conductivity of the cured product is high, but the elongation of the cured product is poor.

[0096] In contrast, in Examples 1 to 4, which use a combination of polyoxypropylenediamine, a polyetheramine with a weight-average molecular weight of 430, and polyetheramines or polyamidoamines with a weight-average molecular weight in the range of 500 to 4000 as the polyamine-based curing agent, the filling rate of aluminum hydroxide is high at 88% or more, so the thermal conductivity of the cured product is high and rated as good.In addition, the inclusion of polyetheramines or polyamidoamines with a weight-average molecular weight in the range of 500 to 4000 results in adhesive shear strength and shear displacement being rated as good, and the elongation of the cured product is also high and rated as good.

[0097] That is, in Examples 1 to 4, even when the filling rate of aluminum hydroxide is high, the inclusion of polyetheramines or polyamidoamines with a weight-average molecular weight in the range of 500 to 4000 as the polyamine-based curing agent ensures adhesive shear strength and shear displacement, and the cured product is able to elongate. The reason for this is not entirely clear, but it is speculated that polyamine-based curing agents with a weight-average molecular weight in the range of 500 to 4,000 open the epoxy groups at room temperature, and the curing agent itself becomes incorporated into part of the epoxy resin network structure. This incorporates a long-chain structure (long molecular chain) into part of the epoxy resin skeleton, increasing the molecular weight between crosslinks and imparting flexibility and pliability, resulting in elongation. It is also thought that the incorporation of ether bonds or polyoxyalkylene bonds into the epoxy resin skeleton may contribute to flexibility through the free vibration and free rotation of the ether groups.

[0098] Here, if the molecular weight of the polyamine-based curing agent is too small, the flexibility and pliability provided by the long chain structure described above cannot be obtained, while if the molecular weight of the polyamine-based curing agent is too large, poor curing occurs. Therefore, it is presumed that if the molecular weight of the polyamine-based curing agent is too large, the polyamine-based curing agent cannot be fully incorporated into the skeleton of the epoxy resin, and unreacted free long-chain amines remain, which ultimately results in a lack of elongation in the cured product.

[0099] According to experimental research by the present inventors, it has been confirmed that polyamine-based curing agents with a weight-average molecular weight in the range of 500 to 4000 are less likely to cause curing defects and can provide elongation of the cured product even when highly loaded with aluminum hydroxide. Polyamine-based curing agents with a weight-average molecular weight in the range of 600 to 3500, more preferably 600 to 2000, can increase shear adhesive strength and shear displacement.

[0100] In Examples 1 to 4, even with a high aluminum hydroxide filling rate, the shear adhesive strength and shear displacement were ensured. This is presumably because the inclusion of polyetheramines with a weight-average molecular weight in the range of 500 to 4000 imparts the aforementioned flexibility and pliability, and polyetheramines and polyamidoamines reduce the amount of heat generated during the curing process, resulting in little residual stress upon curing and little stress due to differences in the thermal expansion coefficients between the interfaces of the adherends, and the inclusion of core-shell rubber particles further toughens the cured product.

[0101] Thus, the curable compositions of Examples 1 to 4 described above use a polyamine-based curing agent such as polyetheramines or polyamidoamines with a weight-average molecular weight in the range of 500 to 4000, and even with a high loading of aluminum hydroxide of 86% by mass or more and 95% by mass or less, the cured product is extensible, and the shear adhesive strength and shear displacement are high, ensuring adhesive strength, while achieving both high thermal conductivity and shape conformability. This makes it possible to enhance the heat dissipation effect.

[0102] In addition, according to the curable compositions of Examples 1 to 4, by using a polyamine-based curing agent having a molecular weight in the range of 500 or more and 4000 or less in combination with a polyamine-based curing agent having a molecular weight in the range of 100 or more and less than 500, the curing time can be shortened compared to when only a polyamine-based curing agent having a molecular weight in the range of 500 or more and 4000 or less is used, and fast curing, high thermal conductivity, and shape conformability can all be achieved at the same time.

[0103] As described above, the curable composition of the above embodiment is a curable composition containing an epoxy resin, a room-temperature curing polyaddition type curing agent, a thermally conductive filler, and core-shell type rubber particles, wherein the room-temperature curing polyaddition type curing agent includes a polyamine-based curing agent having a weight-average molecular weight in the range of 500 to 4000, and the thermally conductive filler is aluminum hydroxide.

[0104] According to the curable composition of the above embodiment, the high loading of aluminum hydroxide increases the thermal conductivity of the cured product. Furthermore, by combining an epoxy resin with a room-temperature-curing polyaddition-type curing agent (a polyamine-based curing agent with a weight-average molecular weight in the range of 500 to 4000) and core-shell rubber particles, the cured product can maintain its extensibility and adhesive strength (shear adhesive strength and shear displacement) even at a high loading of aluminum hydroxide. In other words, the cured product can achieve both high thermal conductivity and shape conformability. Therefore, the thermal conductivity of the cured product can be increased, and the shape conformability of the cured product allows it to conform to the deformation of the heat dissipation object, reducing contact thermal resistance with the heat dissipation object and effectively conducting heat from the heat dissipation object to the cured product, thereby enhancing the heat dissipation effect.

[0105] More preferably, if a bisphenol F epoxy resin is used, the cured product of the curable composition can have a higher elongation percentage, thereby improving its ability to conform to the heat dissipation target. This allows the heat of the heat dissipation target to be conducted by the cured product, and also reduces the contact surface thermal resistance, thereby further improving the heat dissipation effect.

[0106] In the curable composition of the above embodiment, the amount of aluminum hydroxide blended is preferably 86% by mass or more and 95% by mass or less, more preferably 87% by mass or more and 95% by mass or less, and even more preferably 87% by mass or more and 90% by mass or less, relative to 100% by mass of the total amount of the curable composition, thereby achieving both ease of application and high thermal conductivity.

[0107] In the curable composition of the above embodiment, the amine-based curing agent having a weight-average molecular weight in the range of 500 to 4000 is preferably a polyetheramine or a polyamidoamine, which can improve elongation and adhesive strength and shape conformability. More preferably, polyetheramines allow for higher loading of aluminum hydroxide, and this is easy to achieve, improving workability in producing the composition.

[0108] In the curable composition of the above embodiment, the room temperature curable polyaddition curing agent is a combination of a polyamine-based curing agent having a weight average molecular weight in the range of 500 or more and 4000 or less, preferably 600 or more and 3500 or less, and more preferably 600 or more and 2000 or less, and a polyamine-based curing agent having a weight average molecular weight (MW) in the range of 100 or more and less than 500, preferably 120 or more and 480 or less, and more preferably 150 or more and 450 or less. Therefore, by including a polyamine-based curing agent having a weight average molecular weight in the range of 100 or more and less than 500, preferably 120 or more and 480 or less, and more preferably 150 or more and 450 or less, the curing speed can be increased.

[0109] However, when practicing the present invention, fast curing is not necessarily required, so a polyamine-based curing agent with a weight-average molecular weight (MW) of 100 or more and less than 500 may be omitted, and even when fast curing is required, the curing agent is not limited to a polyamine-based curing agent with a weight-average molecular weight (MW) of 100 or more and less than 500, and a room temperature curing polyaddition type curing agent such as polymercaptans may also be used. However, polyamine-based curing agents with a weight-average molecular weight (MW) of 100 or more and less than 500 are excellent in fast curing properties and can also increase adhesive strength.

[0110] In the curable composition of the above embodiment, the core-shell type rubber particles are blended in an amount within the range of preferably 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, and even more preferably 20 to 40 parts by mass, relative to 100 parts by mass of the epoxy resin, so that toughness can be ensured without impairing the viscosity characteristics that allow high loading of aluminum hydroxide.

[0111] In the curable composition of the above embodiment, the core-shell type rubber particles have a median primary particle diameter, as measured by a laser diffraction / scattering method, of preferably 10 to 1500 nm, more preferably 20 to 1200 nm, and even more preferably 30 to 1000 nm, so that the core-shell type rubber particles have high dispersibility, thereby providing stable properties for the cured product.

[0112] In the curable composition of the above embodiment, the thermal conductivity of the cured product obtained by curing the composition is preferably within the range of 2.0 to 5.0 W / m·K, more preferably 3.1 to 4.5 W / m·K, and even more preferably 3.3 to 4.0 W / m·K, thereby making it possible to improve heat dissipation properties.

[0113] In the curable composition of the above embodiment, the elongation at break of a dumbbell-shaped No. 6 test piece of the cured product obtained by curing the composition in accordance with JIS K6249 is preferably within the range of 1.0 to 5.0%, more preferably 1.0 to 3.0%, and even more preferably 1.4 to 2.0%, thereby making it possible to improve shape conformability.

[0114] In the curable composition of the above embodiment, the shear adhesive strength of the cured product obtained by curing the composition, as measured in accordance with JIS K6850, is preferably within the range of 4.0 to 8.0 MPa, more preferably 5.0 to 8.0 MPa, thereby enabling improvement in shape conformability.

[0115] The above-described embodiment can also be understood as an invention of a cured product obtained by curing a curable composition containing an epoxy resin, a room-temperature curing polyaddition curing agent, a thermally conductive filler, and core-shell rubber particles, wherein the polyaddition curing agent includes a polyamine-based curing agent having a weight-average molecular weight in the range of 500 to 4000, preferably 600 to 3500, and more preferably 600 to 2000, and the thermally conductive filler is aluminum hydroxide.

[0116] According to the cured product of the above embodiment, the high loading of aluminum hydroxide increases the thermal conductivity of the cured product. Furthermore, the cured product is a cured product of a cured product composition that combines an epoxy resin, a room-temperature curing polyaddition-type curing agent (a polyamine-based curing agent with a weight-average molecular weight in the range of 500 to 4000), and core-shell rubber particles. Even with a high loading of aluminum hydroxide, the cured product maintains sufficient extensibility and adhesive strength (shear adhesive strength, shear displacement). In other words, high thermal conductivity and conformability are both achieved. Therefore, the enhanced thermal conductivity and conformability allow the cured product to follow the deformation of the heat dissipation object, reducing contact thermal resistance with the heat dissipation object and effectively conducting heat from the heat dissipation object to the cured product, thereby enhancing the heat dissipation effect.

[0117] The curable composition and its cured product according to the above-described embodiment are described as being suitable for use as an adhesive to bond battery cells and a casing (battery module or battery pack) of a battery that generates heat during charging and discharging, such as a lithium-ion battery mounted on an electric vehicle (xEV), and as a heat-conducting material or heat-dissipating material that conducts battery heat to the casing. However, they can also be used as a gap filler, sealant, or sealing material that is applied to electronic components such as a battery, battery module, or battery pack casing to fill air pockets or gaps. That is, for example, by applying the curable composition to the inside of the casing of a battery module or battery pack, attaching a battery cell to the composition, and leaving it at room temperature, the curable composition hardens to bond the battery cell and the casing, eliminating the gap (air layer) between the battery cell and the casing, and dissipating heat from the battery cell to the casing via the thermally conductive cured product. In particular, the curable composition of the above embodiment has extensibility and adhesive strength, so it can follow the expansion and contraction of the battery cell due to heat and is less likely to create gaps between the battery cell and the curable composition, resulting in a high heat dissipation effect.

[0118] However, when carrying out the present invention, the use is not limited to a heat conducting material that conducts the heat of the battery to the housing side or a heat dissipating material. The curable composition of the present invention can be used for, for example, electronic parts, electronic devices, precision parts, etc. in the fields of electronics, magnetism, catalysts, structures, optics, medicine, automobiles, architecture, home appliances, office automation equipment, etc., specifically, parts for household electrical appliances such as personal computers, game consoles, VTRs, televisions, irons, air conditioners, air purifiers, negative ion generators, vacuum cleaners, refrigerators, irons, beauty equipment such as hair dryers, lighting equipment, rice cookers, microwave ovens, microwave cooking pots, heat-resistant tableware, etc.; electric and electronic parts such as personal digital assistants (so-called PDAs), electronic dictionaries, e-books, portable televisions, compact discs, laser discs (registered trademark), drives and readers for recording media (CDs, MDs, DVDs, next-generation high-density discs, hard disks, IC cards, smart media, memory sticks, etc.), ferrules for optical cables, coils, sealants for semiconductor elements and resistors, terminal blocks, printed circuit boards, circuit boards, chips, thermal heads, sensors, connectors, sockets, relay parts, coil bobbins, optical pickups, oscillators, LSIs, CPUs, computer-related parts, etc. , LED lighting, lamp sockets, lamp reflectors, lamp housings and other lighting fixture parts, CRT, LCD, plasma, projectors, organic EL, audio back panels and other display devices, stereos, speakers and other audio product parts, printers, copiers, scanners, fax machines, separation claws, heater holders and other copying and printing machine related parts, pachinko, slot machines and other gaming machine related parts, impellers, fan gears, gears, bearings, motor parts and cases and other mechanical parts, power distribution parts such as breakers, automotive mechanical parts, engine parts, engine room parts, lamp reflectors, lamp housings, instrument panels, center console panels, deflectors, lamps, car stereos, car navigation, car audio visuals, auto mobile computer parts and other electrical and interior parts for automobiles and other vehicles (automotive electrical parts), aircraft and spacecraft parts, sensor parts, telephones (mobile phones, landlines, etc.), modems and other communication equipment parts (communication module parts), optical cameras, digital cameras,It can be used as a heat dissipation material or thermally conductive material for the components and cases (including housings and casings) of various electronic components (including semiconductor elements, ECUs, light-emitting elements, circuit boards, power supply units, etc.) such as image display and recording devices such as typewriters, parabolic antennas, power tools, etc., to dissipate (dissipate or exhaust) heat from these heat dissipation objects (heat-generating bodies).

[0119] In carrying out the present invention, the constitution, ingredients, blending, production method, etc. of the curable composition and other parts of the cured product are not limited to those in the above examples. It should be noted that not all of the numerical values ​​given in the embodiments and examples of the present invention indicate critical values, and some numerical values ​​are determined based on factors such as manufacturing costs and ease of manufacturing, and indicate suitable values ​​suitable for implementation. Therefore, even if the numerical values ​​are slightly changed within the allowable range, this does not negate the implementation.

Claims

1. A curable composition comprising an epoxy resin, a room temperature curing polyaddition curing agent, a thermally conductive filler, and core-shell rubber particles, The curable composition, characterized in that the polyaddition type curing agent includes a polyamine-based curing agent having a weight average molecular weight in the range of 500 to 4000, and the thermally conductive filler is aluminum hydroxide.

2. 2. The curable composition according to claim 1, wherein the aluminum hydroxide is contained in an amount of 86% by mass or more and 95% by mass or less, relative to 100% by mass of the total mass of the curable composition.

3. 2. The curable composition according to claim 1, wherein the polyamine-based curing agent having a weight average molecular weight in the range of 500 to 4,000 is a polyetheramine or a polyamidoamine.

4. 2. The curable composition according to claim 1, wherein the polyaddition type curing agent is a combination of a polyamine-based curing agent having a weight-average molecular weight in the range of 500 or more and 4,000 or less and a polyamine-based curing agent having a weight-average molecular weight in the range of 100 or more and less than 500.

5. 2. The curable composition according to claim 1, wherein the core-shell type rubber particles are blended in an amount within a range of 10 to 50 parts by mass per 100 parts by mass of the epoxy resin.

6. 2. The curable composition according to claim 1, wherein the core-shell type rubber particles have a median primary particle diameter in the range of 10 to 1500 nm.

7. 2. The curable composition according to claim 1, wherein the thermal conductivity of a cured product obtained by curing the curable composition is in the range of 2.0 W / m·K or more and 5.0 W / m·K or less.

8. The curable composition according to claim 1, characterized in that the elongation at break of a dumbbell-shaped No. 6 test piece of the cured product obtained by curing the curable composition in a tensile test in accordance with JIS K6249 is in the range of 1.0% or more and 5.0% or less.

9. 2. The curable composition according to claim 1, wherein the shear adhesive strength of a cured product obtained by curing the curable composition, measured in accordance with JIS K6850, is in the range of 4.0 MPa or more and 8.0 MPa or less.

10. A cured product obtained by curing a curable composition containing an epoxy resin, a room-temperature curing polyaddition curing agent, a thermally conductive filler, and core-shell rubber particles, The cured product is characterized in that the polyaddition type curing agent includes a polyamine-based curing agent having a weight average molecular weight in the range of 500 to 4000, and the thermally conductive filler is aluminum hydroxide.

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