Curable thermally conductive adhesive and thermally conductive member

Abstract

A curable thermally conductive adhesive containing a curable binder and a thermally conductive filler, wherein a cured product of the curable thermally conductive adhesive exhibits a reduction in mass of 1.5% or less after undergoing a temperature cycle test involving 20 cycles consisting of three hours at -40°C and three hours at 80°C, and exhibits an elastic modulus of 1.2X108 Pa or less at 80°C.

Description

Curable thermally conductive adhesive and thermally conductive member

[0001] The present invention relates to curable thermally conductive adhesives and thermally conductive members for use in electronic applications such as battery assemblies.

[0002] Thermally conductive compositions are used, for example, by filling a gap between a heat generating element and a heat sink to transfer heat generated by the heat generating element and dissipate it from the heat sink. Thermally conductive compositions are generally curable and are often used in the cured form after being filled. Thermally conductive compositions play an important role in many electronic device applications, such as battery assemblies such as lithium-ion battery (LiB) assemblies for electric vehicles (EVs), power electronic devices, electronic packaging, LEDs, solar cells, and electric grids.

[0003] For example, in applications for LiB assembly for EVs, it is becoming increasingly important to reduce the viscosity of thermally conductive compositions before curing in order to improve the productivity of EVs as the number of EVs produced continues to increase. This is because reducing the viscosity makes it possible to shorten the time required for the application process using a dispenser and the time required for the process of assembling, for example, a module case on top of the applied thermally conductive composition.

[0004] Furthermore, thermally conductive compositions are required to have higher thermal conductivity, and attempts have been made to pack thermally conductive fillers at high densities. Furthermore, in LiB assemblies for EVs, for example, thermally conductive compositions are sometimes required to have higher adhesiveness to various components in order to ensure adhesion to battery cells, module cases, cooling plates, etc. In addition, thermally conductive compositions are expected to be used in various temperature environments, and high reliability is sometimes required so that qualities such as thermal conductivity can be maintained well even in environments where high and low temperatures are repeatedly changed.

[0005] For example, Patent Document 1 discloses a thermally conductive composition that can reduce the minimum mounting gap, has low thermal resistance, and is highly reliable. The thermally conductive composition includes a trifunctional or higher epoxy resin that does not have an aromatic backbone, a liquid bifunctional or lower epoxy resin, a curing agent, a silane compound that does not have any functional groups other than alkoxy groups, and a thermally conductive filler. Here, reliability is specifically evaluated by the absence of peeling in a heat shock test (heat cycle). Furthermore, the epoxy resin disclosed has an average molecular weight (Mn) in the range of 5,000 to 10,000, and various curing agents are also exemplified.

[0006] Japanese Patent Application Laid-Open No. 2022-116587

[0007] As described above, thermally conductive compositions are sometimes required to have low viscosity, high thermal conductivity, and high adhesiveness, while also being highly reliable and capable of maintaining qualities such as thermal conductivity even in environments where high and low temperatures are repeatedly experienced. However, it is difficult for conventional thermally conductive compositions to simultaneously satisfy these required performance characteristics. For example, Patent Document 1 describes that it is possible to achieve high reliability while ensuring high thermal conductivity. However, the use of high molecular weight epoxy resins and curing agents results in high viscosity of the thermally conductive composition, which results in poor workability.

[0008] On the other hand, to lower the viscosity, it is possible to simply use a low-molecular-weight binder or add a plasticizer to lower the viscosity and elastic modulus. However, simply using a low-molecular-weight binder or plasticizer can easily cause problems such as volatilization and foaming on the surface of the thermally conductive composition in an environment where high and low temperatures are repeatedly changed, making it difficult to ensure high reliability.

[0009] Therefore, an object of the present invention is to provide a curable thermally conductive adhesive that has low viscosity yet is highly reliable.

[0010] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by reducing both the mass loss rate after a thermal cycling test and the elastic modulus at 80°C to a certain value or less in a curable thermally conductive adhesive containing a curable binder and a thermally conductive filler, and have completed the present invention as described below. That is, the present invention provides the following [1] to

[15] . [1] A curable thermally conductive adhesive containing a curable binder and a thermally conductive filler, wherein a cured product of the curable thermally conductive adhesive has a mass loss rate of 1.5% or less after a thermal cycling test in which 20 cycles of 3 hours at -40°C and 3 hours at 80°C are repeated, and an elastic modulus at 80°C of 1.2 x 10 ８ [2] The curable thermally conductive adhesive has an elastic modulus of 3.0 × 10 Pa or less. ６The curable thermally conductive adhesive according to [1] above, having a viscosity of 300 Pa·s or less at a shear rate of 3.16 (1 / s) and 25°C, as measured with a rheometer. [3] The curable thermally conductive adhesive according to [1] or [2] above, having a viscosity of 300 Pa·s or less at a shear rate of 3.16 (1 / s) and 25°C, as measured with a rheometer. [4] The curable thermally conductive adhesive according to any one of [1] to [3] above, wherein the binder comprises an epoxy group-containing compound. [5] The curable thermally conductive adhesive according to any one of [1] to [4] above, wherein the binder comprises at least one of an amine and a thiol. [6] The curable thermally conductive adhesive according to any one of [1] to [5] above, wherein the binder comprises an epoxy group-containing compound and an amine. [7] The curable thermally conductive adhesive according to [6] above, wherein the equivalent ratio of the number of active hydrogens in amino groups contained in the amine to the number of epoxy groups in the epoxy group-containing compound [(number of amino groups) / number of epoxy groups] is 1.2 or more and 2.9 or less. [8] The curable thermally conductive adhesive according to any one of [1] to [7] above, which is composed of a first part containing a base agent of the binder and filled in a first container, and a second part containing a curing agent that hardens when mixed with the first part and filled in a second container. [9] The curable thermally conductive adhesive according to [8] above, in which the difference in viscosity (Pa·s) between the first part and the second part (Pa·s) is 150 Pa·s or less.

[10] The curable thermally conductive adhesive according to [8] or [9] above, in which the ratio of the functional group concentration (mol / g) of the second part to the functional group concentration (mol / g) of the first part is 1.2 or more and 2.9 or less.

[11] A container set filled with the curable thermally conductive adhesive according to any one of [8] to

[10] above, comprising a first container filled with the first part and a second container filled with the second part.

[12] A thermoplastic elastomer comprising a polymer matrix and a thermally conductive filler, wherein the mass loss rate after a thermal cycle test at −40° C. for 3 hours and at 80° C. for 3 hours is 1.5% or less, and the elastic modulus at 80° C. is 1.2×10 ８

[13] A thermally conductive member comprising a cured product of the curable thermally conductive adhesive according to any one of [1] to

[12] above.

[14] A battery assembly comprising the thermally conductive member according to

[12] or

[13] above.

[15] Use of the curable thermally conductive adhesive according to any one of [1] to

[10] above as at least one of a gap material between battery cells, a gap material between a battery cell and a module housing, a gap material between a battery module and a battery pack housing, and a gap material between a battery cell and a battery pack housing.

[0011] According to the present invention, a curable thermally conductive adhesive is provided that has low viscosity and high reliability.

[0012] 1 is a schematic diagram showing a container set according to an embodiment; FIG. 2 is a schematic diagram showing a container set according to an embodiment; FIG. 3 is a perspective view showing a typical configuration of a battery module according to the present invention; FIG. 4 is a perspective view showing a typical configuration of a battery cell included in the battery module; FIG. 5 is a perspective view showing a battery assembly having a cell-to-pack structure;

[0013] [Curable Thermally Conductive Adhesive] The curable thermally conductive adhesive of the present invention will be described in detail below. The curable thermally conductive adhesive of the present invention includes a curable binder and a thermally conductive filler. In the present invention, the curable thermally conductive adhesive has a mass loss rate of 1.5% or less after a thermal cycling test in which 20 cycles of heating at −40° C. for 3 hours and 80° C. for 3 hours are repeated, and a modulus of elasticity at 80° C. is 1.2×10 ８ The curable thermally conductive adhesive having the above-described configuration can ensure low viscosity, high thermal conductivity, and high adhesiveness while also increasing reliability. Therefore, even when the cured product is subjected to a thermal cycle test, it can maintain good thermal conductivity and other properties without generating volatilization marks or peeling from the adherend. The curable thermally conductive adhesive of the present invention will be described in detail below.

[0014] <Mass Loss Rate After Thermal Cycle Test> The curable thermally conductive adhesive of the present invention (hereinafter sometimes simply referred to as "adhesive") has a mass loss rate of 1.5% or less after a thermal cycle test in which the cured product is subjected to 20 cycles of heating at -40°C for 3 hours and heating at 80°C for 3 hours. If the mass loss rate after the thermal cycle test exceeds 1.5%, foaming may occur due to partial volatilization of the adhesive during the thermal cycle test, resulting in volatilization marks, which may also occur during actual use. The occurrence of volatilization marks can result in reduced thermal conductivity and adhesiveness, and, if the thermally conductive member is insulating, can also result in reduced insulation. The mass loss rate after the thermal cycle test is preferably 1.4% or less, more preferably 1.25% or less, and even more preferably 1.0% or less. Furthermore, from the viewpoint of reliability, the lower the mass loss rate after the thermal cycling test, the better, but from the viewpoint of making the adhesive have a low viscosity before curing, it is better that the mass loss rate is at least a certain value, preferably at least 0.05%, more preferably at least 0.1%, and even more preferably at least 0.2%. Furthermore, from the viewpoint of a balance between making the adhesive have a low viscosity before curing and reliability, the mass loss rate after the thermal cycling test is preferably at least 0.05% and at most 1.5%, more preferably at least 0.1% and at most 1.4%, and even more preferably at least 0.2% and at most 1.25%.

[0015] The mass loss rate after the thermal cycling test can be obtained by performing the thermal cycling test on a 1 mm thick test sample (cured product) obtained by curing the adhesive, measuring the mass loss of the test sample due to the thermal cycling test, and determining the percentage (%) of mass loss relative to the test sample before the thermal cycling test. The mass loss rate after the thermal cycling test can be adjusted, for example, by the type and amount of each component constituting the binder, and can be reduced, for example, by using a component with low volatility as the binder or a component that does not decompose even when heated.

[0016] <Elastic Modulus> The adhesive of the present invention has a cured product with an elastic modulus of 1.2 × 10 at 80°C. ８ The elastic modulus at 80°C is 1.2 × 10 ８If the compressive strength is higher than Pa, the flexibility of the adhesive is impaired, making it difficult to follow changes in the gap between adherends. As a result, peeling is more likely to occur in a thermal cycle test, and peeling from the adherend is also more likely to occur in actual use. Peeling from the adherend can lead to a decrease in heat dissipation characteristics and a decrease in strength as a structural member when the adhesive is used as a thermally conductive member. In addition, volatilization marks due to foaming are more likely to occur, making it difficult to improve the reliability of the adhesive. The elastic modulus of the cured product at 80°C is 1.1 x 10 ８ Pa or less, and 1.0 × 10 ８ Pa or less is more preferable, and 0.85 × 10 ８ Furthermore, the modulus of elasticity of the cured product at 80°C should be a certain value or more from the viewpoint of ensuring adhesive strength at high temperatures, for example, 3.0 x 10 ６ Pa or more, preferably 1.0 × 10 ７ Pa or more, more preferably 2.0 × 10 ７ Pa or more, more preferably 3.0 × 10 ７ In addition, from the viewpoint of the adhesive's ability to follow changes in the gap between adherends and from the viewpoint of improving the reliability of the adhesive, the elastic modulus of the cured product at 80°C is 1.0 × 10 ７ Pa or more 1.2×10 ８ Pa or less, and 2.0 × 10 ７ Pa or more 1.1×10 ８ Pa or less is more preferable, and 3.0 × 10 ７ Pa or more 1.0×10 ８ Pa or less is more preferable.

[0017] The adhesive of the present invention has a modulus of elasticity of 1.0×10 at −40° C. after curing. ９ Pa or more 5.0×10 １１ By setting the modulus of elasticity of the cured product at -40°C within the above range, it becomes easier to increase reliability and ensure adhesive strength at low temperatures. The modulus of elasticity of the cured product at -40°C is preferably 5.0 x 10 ９ Pa or more 1.0×10 １１ Pa or less, and more preferably 9.0 × 10 ９ Pa or more 5.0×10 １０It is more preferable that the viscosity is 0.05 Pa or less.

[0018] The adhesive of the present invention has a cured product with an elastic modulus of 1.0 × 10 at 25°C. ７ Pa or more 1.0×10 １１ By setting the modulus of elasticity of the cured product at 25°C within the above range, reliability can be increased and adhesive strength at room temperature can be easily ensured. In addition, the modulus of elasticity at high temperatures can be easily adjusted to an appropriate value. The modulus of elasticity of the cured product at 25°C is preferably 8.0 x 10 ７ Pa or more 7.0×10 １０ Pa or less, and more preferably 3.0 × 10 ８ Pa or more 2.0×10 １０ It is more preferable that the viscosity is 0.05 Pa or less.

[0019] The elastic modulus of the cured adhesive is the storage modulus determined for a 1 mm thick test sample obtained by curing the adhesive using a dynamic viscoelasticity measuring device under the measurement conditions described in the Examples. The elastic modulus of the cured adhesive can be adjusted by the type and amount of each component constituting the binder. For example, it can be lowered by adjusting the type and amount of each component constituting the binder so as to lower the crosslink density, or by using a binder with high flexibility. The elastic modulus at 80°C can also be easily lowered by appropriately increasing the amount of low-molecular-weight binder curing agent used. As described above, the present invention provides a cured product having a mass loss rate of 1.5% or less after a thermal cycling test, and an elastic modulus of the cured product at 80°C of 1.2 x 10 ８ A highly reliable curable thermally conductive adhesive can be obtained by setting the viscosity at or below 100 Pa. More specifically, even if the viscosity of the adhesive is lowered by using a certain low-viscosity component, by setting the parameter within the above range, it is possible to suppress the occurrence of volatilization marks and peeling, and a highly reliable curable thermally conductive adhesive can be obtained.

[0020] <Glass Transition Point> The adhesive of the present invention preferably has a glass transition point of -80°C or higher and -40°C or lower. When the glass transition point of the cured product is equal to or lower than the upper limit, the change in elastic modulus is small within the temperature range of the thermal cycle test (-40°C to 80°C), making it easier to increase reliability. Furthermore, when the glass transition point is equal to or higher than the lower limit, a larger number of resin types can be employed, increasing design freedom. On the other hand, a cured product of an adhesive having the above elastic modulus may have a glass transition point above -40°C. In this case, the glass transition point is preferably equal to or higher than 15°C and 55°C, more preferably equal to or higher than 20°C and 48°C, and even more preferably equal to or higher than 26°C and 46°C. The change in elastic modulus is small within the temperature range above the glass transition point, making it easier to increase reliability. Furthermore, when the glass transition point is equal to or higher than the lower limit, it is easier to ensure adhesive strength at high temperatures. The glass transition point of the cured adhesive can be measured using a 1 mm thick test sample (cured product) obtained by curing the adhesive using a dynamic viscoelasticity measuring device described in the Examples. The glass transition temperature can be adjusted by the type and amount of each component constituting the binder.

[0021] The test samples used in the above-mentioned measurements of mass loss, modulus, and glass transition point were obtained by fully curing the adhesive, and specifically, differential scanning calorimetry was performed on the resulting cured product, which showed that the heat generated by the curing reaction was 0.1 mJ / mg or less after 2 hours at 25° C. In the case of a two-component adhesive, for example, curing can be carried out by mixing the first and second parts and then leaving the mixture at room temperature (25° C.) for a long period of time (for example, 7 days).

[0022] <Viscosity> The adhesive of the present invention preferably has a viscosity of 300 Pa·s or less. The viscosity is measured using a rheometer, adjusting the sample temperature to 25°C with a Peltier plate, using parallel plates with a diameter of 25 mm, while continuously changing the shear rate within a range of 0.0001 to 100 (1 / s), and is the value at a shear rate of 3.16 (1 / s). For example, an Anton Paar MCR-302e rheometer is used as the rheometer. When measuring the viscosity of a two-component curing adhesive after mixing the first and second components, the sample is immediately placed in the rheometer after mixing the first and second components, and the viscosity is measured promptly. On the other hand, when measuring the viscosity of the first and second components before mixing, the sample is placed in the rheometer and allowed to stand for 10 minutes before measuring the viscosity.

[0023] By setting the viscosity of the adhesive to 300 Pa·s or less, the adhesive can be easily applied to the adherend, improving workability. Furthermore, the adhesive can be easily filled into narrow gaps. The viscosity is preferably 250 Pa·s or less, and more preferably 200 Pa·s or less. Furthermore, the viscosity may be, for example, 10 Pa·s or more, but from the viewpoint of filling a certain amount or more of thermally conductive filler to prevent dripping, etc., a viscosity of 30 Pa·s or more is preferred, and 50 Pa·s or more is more preferred.

[0024] <Adhesive Strength> The adhesive of the present invention can ensure high adhesive strength by increasing the adhesive strength after curing. Therefore, the higher the adhesive strength of the adhesive after curing, the better, for example, 1 MPa or more, preferably 2 MPa or more, more preferably 3 MPa or more, and even more preferably 3.8 MPa or more. The higher the adhesive strength of the adhesive after curing, the better, but in practical terms, it is, for example, 25 MPa or less. Furthermore, by ensuring that the elongation at maximum load after curing is a certain value or more, flexibility can be ensured and reliability can be easily improved. The adhesive of the present invention has an elongation at maximum load after curing of, for example, 0.5 mm or more, preferably 0.6 mm or more, more preferably 0.7 mm or more, and even more preferably 0.75 mm or more. Furthermore, the elongation at maximum load is not particularly limited, but in order to impart a certain adhesive strength, it is, for example, 3 mm or less, preferably 2 mm or less.

[0025] The adhesive strength and elongation at maximum load of the cured adhesive can be measured using the following test method. First, two 25 mm x 100 mm, 2 mm thick PET plates are prepared. The two plates are then overlapped end-to-end with the adhesive, and the adhesive is cured to bond the ends of the plates together, obtaining a measurement sample. The ends of the plates are bonded together with a 25 mm x 5 mm, 1 mm thick cured adhesive. The maximum load measured when the obtained measurement sample is pulled in the longitudinal direction using a tensile tester is defined as the adhesive strength, and the elongation of the cured product at the maximum load is defined as the elongation at maximum load. The tensile speed is preferably 10 mm / sec. The adhesive is cured by fully curing the adhesive between the PET plates. Here, fully curing is as described above. For example, in the case of a two-component adhesive, the adhesive can be cured by mixing the first and second parts, applying the mixture between the PET plates, and then leaving it at room temperature (25°C) for 168 hours.

[0026] <Thermal Conductivity> The adhesive of the present invention preferably has a thermal conductivity of 1.5 W / (m·K) or more, more preferably 1.7 W / (m·K) or more, and even more preferably 1.9 W / (m·K) or more after curing. By ensuring that the thermal conductivity of the cured adhesive is equal to or greater than these lower limits, the adhesive exhibits good thermal conductivity. Therefore, when used in, for example, a battery cell assembly, heat generated from the battery cell can be efficiently transferred to the module housing and battery pack via the cured adhesive (thermally conductive member), thereby preventing excessive increases in the temperature of the battery cell. The higher the thermal conductivity, the better; however, in practical use, it is, for example, 7.0 W / m·K or less. Thermal conductivity can be measured using a method in accordance with ASTM D5470-06. Specifically, a larger amount of adhesive is applied to cover the measurement die (which is the heat source side) than the actual thickness at the time of measurement. The die is then sandwiched between heat sinks and compressed under a load of 30 psi until the adhesive reaches thicknesses of 1.0 mm, 1.5 mm, and 2.0 mm, and the thermal resistance is measured for each thickness. The thickness can be adjusted using spacers. A graph is created for these three thermal resistance values, with the horizontal axis representing thickness and the vertical axis representing thermal resistance value, and a three-point approximation line is found using the least squares method. The slope of this approximation line is then taken as the thermal conductivity.

[0027] [Binder] The adhesive of the present invention includes a curable binder. The curable binder may be thermosetting, photocurable, or moisture-curable, but is preferably thermosetting. The binder may be either a one-component curing type or a two-component curing type, but is preferably a two-component curing type. The two-component curing type is used by mixing a first component containing a base agent with a second component containing a curing agent, and curing is preferably initiated by mixing the first component and the second component. Therefore, in the two-component curing type, it is preferable to use a curing agent that cures when mixed with the base agent of the first component. It is also preferable that the curing agent be one that can be mixed with the base agent of the first component and cure at room temperature (25°C).

[0028] The binder is preferably a urethane-based, silicone-based, acrylic-based, epoxy-based, or organic polymer having a hydrolyzable silyl group. Among these, epoxy-based, urethane-based, and organic polymer having a hydrolyzable silyl group are more preferred, and epoxy-based are even more preferred. The use of these specific binders makes it easier to adjust the mass loss rate after a thermal cycling test and the elastic modulus at 80°C to fall within the above-mentioned specified ranges.

[0029] <Urethane-based binder> Here, the urethane-based binder may be, for example, one composed of a polyol compound as a main component and a polyisocyanate compound as a curing agent. Therefore, in the case of a two-component curing type, it is preferable that the first component contains a polyol compound and the second component contains a polyisocyanate compound. The urethane-based binder will be described in detail below.

[0030] (Polyol Compound) The polyol compound used in the present invention is not particularly limited, but examples thereof include polyester polyol, polyether polyol, polycarbonate polyol, and polymer polyol.

[0031] The polyester polyol may be a polyester polyol having an aromatic ring or an aliphatic polyester polyol. Examples of polyester polyols include polyester polyols obtained by reacting a polycarboxylic acid with a polyol, and caprolactone polyols such as poly-ε-caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone. Examples of polycarboxylic acids used as raw materials for polyester polyols include dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylenedicarboxylic acid, and dodecamethylenedicarboxylic acid. Examples of the polyol that can be used as a raw material for the polyester polyol include diols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and cyclohexanediol.

[0032] Examples of polyether polyols include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene ether glycol, polymethyltetramethylene glycol, and random or block copolymers of these alkylene glycols or their derivatives. The polyether polyol may also be a polyalkylene polyol obtained by ring-opening addition polymerization of an alkylene oxide (e.g., ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, etc.) to an initiator having two or more active hydrogen atoms. Specific examples of initiators include aliphatic polyhydric alcohols, more specifically, glycols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexylene glycol, and cyclohexanedimethanol; triols such as trimethylolpropane and glycerin; tetrafunctional alcohols such as pentaerythritol; and highly functional initiators such as sucrose and sorbitol. Other examples include aliphatic amines such as alkylenediamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, and neopentyldiamine; alkanolamines such as monoethanolamine and diethanolamine; and aromatic amines such as aniline, tolylenediamine, xylylenediamine, diphenylmethanediamine, and Mannich condensation products. Furthermore, bisphenol-type polyalkylene polyols obtained by addition reaction of alkylene oxide with the active hydrogen moiety of a bisphenol-type molecular skeleton may also be used.

[0033] Examples of polycarbonate polyols include poly(3-methyl-1,5-pentylene carbonate) diol, polypentamethylene carbonate diol, and polytetramethylene carbonate diol.

[0034] Examples of polymer polyols include polymers obtained by graft polymerizing ethylenically unsaturated compounds such as acrylonitrile, styrene, methyl acrylate, and methacrylate onto aromatic polyols, alicyclic polyols, aliphatic polyols, and polyester polyols, and hydrogenated polybutadiene polyols. Examples of aromatic polyols used in the production of polymer polyols include bisphenol A, bisphenol F, phenol novolac, and cresol novolac. Examples of alicyclic polyols used in the production of polymer polyols include cyclohexanediol, methylcyclohexanediol, isophoronediol, dicyclohexylmethanediol, and dimethyldicyclohexylmethanediol. Examples of aliphatic polyols used in the production of polymer polyols include ethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol.

[0035] Among the above polyol compounds, polyether polyols are preferred, and polyalkylene glycols are more preferred. Use of polyether polyols makes it easier to reduce the storage modulus.

[0036] The average molecular weight of the polyol compound is not particularly limited, but is preferably 300 or more, more preferably 500 or more, and even more preferably 700 or more. By increasing the average molecular weight of the polyol compound, it becomes easier to lower the storage modulus value. The average molecular weight of the polyol compound is also not particularly limited, but is, for example, 20,000 or less, preferably 10,000 or less, more preferably 5,000 or less, and even more preferably 3,500 or less. The average molecular weight of the polyol compound can be calculated by measuring the hydroxyl value (mg KOH / g) and using the following formula: Average molecular weight = hydroxyl value × N × 1,000 / 56.11, where N is the average number of functional groups of the polyol. The hydroxyl value can be measured according to JIS K 1557-1.

[0037] (Polyisocyanate Compound) Examples of polyisocyanate compounds include aromatic polyisocyanate compounds and aliphatic polyisocyanate compounds. Examples of aromatic polyisocyanate compounds include diphenylmethane diisocyanate, tolylene diisocyanate, and naphthalene-1,5-diisocyanate. Examples of aliphatic polyisocyanate compounds include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, norbornane diisocyanate, transcyclohexane-1,4-diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, cyclohexane diisocyanate, bis(isocyanatomethyl)cyclohexane, and dicyclohexylmethane diisocyanate. The polyisocyanate compound may be any of the above-mentioned modified products, such as a liquid modified product of diphenylmethane diisocyanate or polymeric MDI, or may be a biuret, isocyanurate, or adduct of the above-mentioned polyisocyanate compound.

[0038] The content of the polyol compound and the polyisocyanate compound in the adhesive is, for example, in the range of 1.0 to 4.0, preferably 1.5 to 3.0, in terms of the molar ratio ([NCO] / [OH]) of the hydroxyl group (OH) in the polyol compound to the isocyanate group (NCO) in the polyisocyanate compound. The molar ratio ([NCO] / [OH]) is also referred to as the equivalent ratio.

[0039] <Silicone-based binder> The silicone-based binder may be either a condensation curing type silicone resin or an addition reaction curing type silicone resin, but an addition reaction curing type silicone resin is preferred. The addition reaction curing type silicone resin is preferably composed of a silicone resin constituting a main component and a curing agent that cures the main component, and for example, in the case of an addition reaction curing type silicone resin, it is preferable to use an organopolysiloxane having an alkenyl group as the main component and an organohydrogenpolysiloxane as the curing agent.

[0040] <Organic Polymer Having Hydrolyzable Silyl Group> The organic polymer having a hydrolyzable silyl group has a hydrolyzable silyl group, and is hydrolyzed by moisture such as humidity to form a silanol group. After that, the silanol groups undergo condensation polymerization with each other or with the hydrolyzable silyl group to form a siloxane bond. As a result, the organic polymer forms a crosslinked structure and hardens to obtain a rubber-like elastomer. Note that the silanol group refers to a hydroxy group (Si—OH) directly bonded to a silicon atom.

[0041] A hydrolyzable silyl group is a group in which 1 to 3 hydrolyzable groups are bonded to a silicon atom. The hydrolyzable groups of the hydrolyzable silyl group are not particularly limited, and examples thereof include a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, a mercapto group, and an alkenyloxy group. Among these, an alkoxysilyl group is preferred as the hydrolyzable silyl group because of its mild hydrolysis reaction. Examples of the alkoxysilyl group include trialkoxysilyl groups such as trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, and triphenoxysilyl groups; dialkoxysilyl groups such as dimethoxymethylsilyl and diethoxymethylsilyl groups; and monoalkoxysilyl groups such as methoxydimethylsilyl and ethoxydimethylsilyl groups. Of these, dialkoxysilyl groups are more preferred, and dimethoxymethylsilyl groups are particularly preferred.

[0042] The organic polymer having a hydrolyzable silyl group may have a linear or branched main chain, but preferably has a linear main chain. That is, the organic polymer having a hydrolyzable silyl group of the present invention preferably has a hydrolyzable silyl group at the end of a linear main chain. When an organic polymer having a hydrolyzable silyl group at the end is used, the cured product becomes more easily elongated and has improved conformability.

[0043] The terminal silylation rate of the organic polymer having a hydrolyzable silyl group is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. When the terminal silylation rate is a certain level or more, it becomes easier to appropriately adjust the curability and elongation of the battery curable adhesive. The terminal silylation rate refers to the ratio of silylated terminals to all terminals of the organic polymer having a hydrolyzable silyl group. There is no particular upper limit to the terminal silylation rate, but it is, for example, 100% or less, and in practical use, can be 99% or less. The terminal silylation rate of the organic polymer having a hydrolyzable silyl group is １ It is determined by H-NMR.

[0044] The average number of hydrolyzable silyl groups in one molecule of an organic polymer having hydrolyzable silyl groups is preferably 1 to 3. When the number of hydrolyzable silyl groups in the polymer is within this range, the adhesive has good curing properties and elongation properties. The average number of hydrolyzable silyl groups in one molecule of an organic polymer having hydrolyzable silyl groups can be measured by the following method: １ It can be calculated based on the concentration of hydrolyzable silyl groups in the organic polymer determined by H-NMR and the number average molecular weight of the polymer determined by GPC.

[0045] The method for introducing a hydrolyzable silyl group into an organic polymer is not particularly limited, and examples thereof include (1) a method in which an organic polymer modified with an unsaturated group in the molecule is subjected to hydrosilylation by the action of a hydrosilane having a hydrolyzable silyl group, (2) a method in which an organic polymer modified with an unsaturated group in the molecule is reacted with a compound having a mercapto group and a hydrolyzable silyl group, and (3) a method in which an organic polymer having a functional group in the molecule is reacted with a compound having a hydrolyzable silyl group and a functional group reactive with the functional group.Specific examples of the reaction that can be used include a reaction between an isocyanate group and a hydroxyl group, a reaction between an isocyanate group and an amino group, and a reaction between an isocyanate group and a mercapto group.

[0046] The organic polymer containing a hydrolyzable silyl group is not particularly limited, and examples thereof include polyalkylene oxides such as polyethylene oxide, polypropylene oxide, polybutylene oxide, polytetramethylene oxide, polyethylene oxide-polypropylene oxide copolymers, and polypropylene oxide-polybutylene oxide copolymers; saturated hydrocarbon polymers; polychloroprene, polyisoprene, copolymers of isoprene or butadiene with acrylonitrile and / or styrene; polybutadiene, copolymers of isoprene or butadiene with acrylonitrile and styrene; (meth)acrylate polymers obtained by radical polymerization of monomers such as ethyl (meth)acrylate and butyl (meth)acrylate; Examples of such polymers include vinyl polymers obtained by radical polymerization of monomers such as vinyl acid, acrylonitrile, and styrene, graft polymers obtained by polymerizing vinyl monomers into the above polymers, polysulfide polymers, nylon 6 obtained by ring-opening polymerization of ε-caprolactam, nylon 6,6 obtained by condensation polymerization of hexamethylenediamine and adipic acid, nylon 6,10 obtained by condensation polymerization of hexamethylenediamine and sebacic acid, nylon 11 obtained by condensation polymerization of ε-aminoundecanoic acid, nylon 12 obtained by ring-opening polymerization of ε-aminolaurolactam, polyamide polymers such as copolymer nylons containing two or more of the above nylon components, polycarbonate polymers produced by condensation polymerization of bisphenol A and carbonyl chloride, and diallyl phthalate polymers. In this specification, (meth)acrylate means methacrylate or acrylate.

[0047] Among these, polyalkylene oxides are preferred as organic polymers from the viewpoint of achieving desired ranges of shear adhesive strength and elongation at maximum stress after curing. That is, polyalkylene oxides having hydrolyzable silyl groups are preferred as organic polymers having hydrolyzable silyl groups. Among polyalkylene oxides, polypropylene oxide is particularly preferred.

[0048] The number-average molecular weight (Mn) of the organic polymer containing hydrolyzable silyl groups is preferably 1,000 to 70,000, more preferably 1,000 to 40,000, even more preferably 1,500 to 30,000, even more preferably 2,000 to 30,000, even more preferably 4,000 to 30,000, and even more preferably 4,000 to 20,000. When the number-average molecular weight of the organic polymer containing hydrolyzable silyl groups is below these upper limits, the viscosity of the resulting adhesive can be reduced. Furthermore, when the number-average molecular weight of the organic polymer containing hydrolyzable silyl groups is above these lower limits, the cured adhesive is prevented from becoming brittle, and the hardness and elongation of the cured adhesive are improved. Note that when the adhesive contains multiple types of organic polymers containing hydrolyzable silyl groups, the number-average molecular weight (Mn) refers to the number-average molecular weight (Mn) of all of them.

[0049] In the present invention, the number average molecular weight of the organic polymer containing a hydrolyzable silyl group refers to a value measured by gel permeation chromatography (GPC) in terms of polystyrene. Measurement by GPC can be performed, for example, using an ACQUITY APC system manufactured by Waters Corporation, a Shodex KF604 GPC column manufactured by Tosoh Corporation, tetrahydrofuran as the solvent, a column temperature of 40° C., and a flow rate of 0.3 ml / min.

[0050] The polymer containing a hydrolyzable silyl group can be a commercially available product. For example, examples of polyalkylene oxide polymers having a polypropylene oxide main chain skeleton and a dimethoxysilyl group at the end of the main chain skeleton include those manufactured by Asahi Glass Co., Ltd. under the product names "Excestar A2410" and "Excestar S4530," and those manufactured by Kaneka Corporation under the product names "S203," "SAT350," and "SAX010."

[0051] <Acrylic Binder> The acrylic binder may be any component that forms an acrylic polymer upon curing, and examples thereof include various acrylic compounds such as alkyl (meth)acrylate, hydroxyalkyl (meth)acrylate, (meth)acrylic acid, (meth)acrylamides, and urethane (meth)acrylate. The acrylic binder may also contain a vinyl monomer copolymerizable with the acrylic compound. Furthermore, at least a portion of the acrylic binder may be a polymer of an acrylic compound, or a copolymer of an acrylic compound and a vinyl monomer. The acrylic binder may also be a monofunctional acrylate compound or a polyfunctional acrylate compound.

[0052] <Epoxy-based binder> The epoxy-based binder preferably comprises an epoxy group-containing compound as a base compound and a curing agent. Hereinafter, the case where an epoxy-based binder is used will be described in detail.

[0053] (Epoxy Group-Containing Compound) As described above, when the binder is an epoxy-based binder, it is preferable that the binder contains an epoxy group-containing compound. By using an epoxy group-containing compound, it becomes easier to increase the adhesive strength of the adhesive, and it also becomes easier to adjust the elastic modulus of the cured adhesive to a predetermined range. The epoxy group-containing compound may be a polyfunctional epoxy group-containing compound or a monofunctional epoxy group-containing compound.

[0054] The adhesive of the present invention preferably contains at least a polyfunctional epoxy group-containing compound. By containing a polyfunctional epoxy group-containing compound, the adhesive can easily increase its adhesive strength. It is more preferable that the adhesive further contains a monofunctional epoxy group-containing compound in addition to the polyfunctional epoxy group-containing compound. By further containing a monofunctional epoxy group-containing compound, the adhesive can prevent the crosslink density after curing from becoming too high, making it easier to reduce the elastic modulus after curing. Furthermore, by using a monofunctional epoxy group-containing compound, it is easier to reduce the viscosity of the adhesive before curing.

[0055] Examples of polyfunctional epoxy group-containing compounds include bifunctional and trifunctional compounds, with bifunctional epoxy group-containing compounds being preferred. Specific examples of polyfunctional epoxy group-containing compounds include aromatic epoxy resins such as phenol novolac epoxy resins, resorcinol epoxy resins, epoxy resins having a bisphenol skeleton, epoxy resins having a naphthalene skeleton, epoxy resins having a fluorene skeleton, epoxy resins having a biphenyl skeleton, epoxy resins having a bi(glycidyloxyphenyl)methane skeleton, epoxy resins having a xanthene skeleton, epoxy resins having an anthracene skeleton, and epoxy resins having a pyrene skeleton. Other examples include epoxy resins having alicyclic skeletons such as epoxy resins having a dicyclopentadiene skeleton and epoxy resins having an adamantane skeleton. Furthermore, aliphatic epoxy resins such as butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and trimethylolpropane polyglycidyl ether are also useful. Hydrogenated or modified versions of the above-listed epoxy resins can also be used as epoxy resins.

[0056] Examples of the epoxy resins having a bisphenol skeleton include epoxy resins having a bisphenol skeleton of bisphenol A type, bisphenol F type, or bisphenol S type. Examples of the resorcinol epoxy resins include resorcinol diglycidyl ether. Examples of the epoxy resins having a naphthalene skeleton include 1,2-diglycidylnaphthalene, 1,5-diglycidylnaphthalene, 1,6-diglycidylnaphthalene, 1,7-diglycidylnaphthalene, 2,7-diglycidylnaphthalene, triglycidylnaphthalene, and 1,2,5,6-tetraglycidylnaphthalene. Examples of the epoxy resin having a fluorene skeleton include 9,9-bis(4-glycidyloxyphenyl)fluorene, 9,9-bis(4-glycidyloxy-3-methylphenyl)fluorene, 9,9-bis(4-glycidyloxy-3-chlorophenyl)fluorene, 9,9-bis(4-glycidyloxy-3-bromophenyl)fluorene, 9,9-bis(4-glycidyloxy-3-fluorophenyl)fluorene, 9,9-bis(4-glycidyloxy-3-methoxyphenyl)fluorene, 9,9-bis(4-glycidyloxy-3,5-dimethylphenyl)fluorene, 9,9-bis(4-glycidyloxy-3,5-dichlorophenyl)fluorene, and 9,9-bis(4-glycidyloxy-3,5-dibromophenyl)fluorene.

[0057] Examples of the epoxy resin having a biphenyl skeleton include 4,4'-diglycidylbiphenyl and 4,4'-diglycidyl-3,3',5,5'-tetramethylbiphenyl. Examples of the epoxy resin having a bi(glycidyloxyphenyl)methane skeleton include 1,1'-bi(2,7-glycidyloxynaphthyl)methane, 1,8'-bi(2,7-glycidyloxynaphthyl)methane, 1,1'-bi(3,7-glycidyloxynaphthyl)methane, 1,8'-bi(3,7-glycidyloxynaphthyl)methane, 1,1'-bi(3,5-glycidyloxynaphthyl)methane, 1,8'-bi(3,5-glycidyloxynaphthyl)methane, 1,2'-bi(2,7-glycidyloxynaphthyl)methane, 1,2'-bi(3,7-glycidyloxynaphthyl)methane, and 1,2'-bi(3,5-glycidyloxynaphthyl)methane.

[0058] Examples of the epoxy resin having a xanthene skeleton include 1,3,4,5,6,8-hexamethyl-2,7-bis-glycidylmethoxy-9-phenyl-9H-xanthene, etc. Examples of the epoxy resin having an anthracene skeleton include those having one or more anthracene skeletons and two or more epoxy groups or glycidyl groups in one molecule.

[0059] Examples of the epoxy resin having a pyrene skeleton include those having one or more pyrene skeletons and two or more epoxy groups or glycidyl groups in one molecule. Examples of the epoxy resin having a dicyclopentadiene skeleton include dicyclopentadiene dioxide and phenol novolac epoxy resins having a dicyclopentadiene skeleton. Examples of the epoxy resin having an adamantane skeleton include 1,3-bis(4-glycidyloxyphenyl)adamantane and 2,2-bis(4-glycidyloxyphenyl)adamantane.

[0060] Among the above, from the viewpoint of improving adhesive strength and reliability, the bifunctional epoxy group-containing compound is preferably an epoxy resin having an aromatic skeleton, and more preferably a bisphenol-type epoxy resin, which is an epoxy resin having a bisphenol skeleton. The bifunctional epoxy group-containing compound may be used alone or in combination of two or more.

[0061] Examples of monofunctional epoxy group-containing compounds include phenyl-based glycidyl ethers such as alkylphenyl glycidyl ethers, such as phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, cresyl glycidyl ether, and nonylphenyl glycidyl ether, and monofunctional epoxy group-containing compounds having an aromatic ring, such as 1-glycidylnaphthalene and 2-glycidylnaphthalene. Examples of monofunctional epoxy group-containing compounds include aliphatic monofunctional epoxy group-containing compounds, specifically glycidyl ethers of aliphatic alcohols, such as butyl glycidyl ether and lauryl glycidyl ether. From the viewpoint of improving adhesive strength and reliability, monofunctional epoxy group-containing compounds having an aromatic ring are preferred, and phenyl-based glycidyl ethers are particularly preferred. The monofunctional epoxy group-containing compounds may be used alone or in combination of two or more.

[0062] It is preferable to use an epoxy group-containing compound with a low molecular weight, as using a low molecular weight compound can reduce the viscosity of the adhesive and enable a high loading of the thermally conductive filler. From this perspective, it is preferable to use an epoxy group-containing compound with a molecular weight of, for example, 1000 or less. There is no particular lower limit for the molecular weight of the epoxy group-containing compound, but it is, for example, 100 or more. Here, the molecular weight of the polyfunctional epoxy group-containing compound is preferably 1000 or less, more preferably 750 or less, even more preferably 500 or less, and preferably 200 or more, more preferably 250 or more, and even more preferably 280 or more. The molecular weight of the monofunctional epoxy group-containing compound is preferably 500 or less, more preferably 300 or less, even more preferably 200 or less, and preferably 100 or more, more preferably 125 or more, and even more preferably 140 or more.

[0063] The epoxy equivalent of the epoxy group-containing compound is preferably 500 g / eq or less, more preferably 375 g / eq or less, even more preferably 250 g / eq or less, and is preferably 100 g / eq or more, more preferably 125 g / eq or more, even more preferably 140 g / eq or less.

[0064] The epoxy group-containing compound is preferably liquid at room temperature (25°C). From the viewpoint of reducing viscosity, the lower the viscosity of the epoxy group-containing compound at 25°C, the better. For example, it may be 50 Pa·s or less, and preferably 10 Pa·s or less. The viscosity of the epoxy group-containing compound at 25°C is not particularly limited, but may be, for example, 0.5 mPa·s or more, or 1 mPa·s or more. The viscosity of the polyfunctional epoxy group-containing compound at 25°C may be, for example, 50 Pa·s or less, preferably 10 Pa·s or less, or 1 mPa·s or more, but in practice it is preferably 10 mPa·s or more, and more preferably 100 mPa·s or more.

[0065] On the other hand, the viscosity of the monofunctional epoxy group-containing compound at 25°C may be, for example, 10 Pa·s or less, preferably 1 Pa·s or less, more preferably 100 mPa·s or less, and may also be, for example, 0.5 mPa·s or more, 1 mPa·s or more, or 3 mPa·s or more. When the binder contains both a polyfunctional epoxy group-containing compound and a monofunctional epoxy group-containing compound, the viscosity of the monofunctional epoxy group-containing compound is preferably lower than the viscosity of the polyfunctional epoxy group-containing compound. The viscosity of the epoxy group-containing compound and the curing agent described below can be measured using a rheometer (e.g., the "MCR-302e" rheometer manufactured by Anton Paar) by adjusting the temperature of the sample to 25°C with a Peltier plate and using a φ50 mm cone plate with a 1° angle, while continuously changing the shear rate within a range of 10 to 100 (1 / sec). The viscosity value is the value at a shear rate of 10 (1 / sec).

[0066] (Curing Agent) The binder preferably contains a curing agent that cures the base material, and specifically, preferably contains at least one of an amine and a thiol. At least one of an amine and a thiol is preferably used when the binder contains an epoxy group-containing compound. By containing an amine or a thiol as a curing agent, the binder can be easily adjusted to a practical curing speed at room temperature. In addition, the adhesive strength of the adhesive can be easily increased.

[0067] The amine may be a polyamine such as a diamine or triamine, or a monoamine, but is preferably a polyamine such as a diamine or triamine. Specific examples of amines include polyoxyalkyleneamines such as polyoxyethylene diamine, poly(oxyethylene / oxypropylene) diamine, polyoxypropylene diamine, poly(oxybutylene / oxypropylene) diamine, polyethylene glycol bis(propylamine), trimethylolpropane poly(oxypropylene) triamine, glyceryl poly(oxypropylene) triamine, and methoxypoly(oxyethylene / oxypropylene)-2-propylamine; m-phenylenediamine, p-phenylenediamine, m-xylylenediamine, p-xylylenediamine, tolylene-2,4-diamine, tolylene-2,6-diamine, mesitylene-2,4-diamine, mesitylene-2,6-diamine, 3,5-diethyltolylene-2,4-diamine, 3,5-diethyltolylene-2,6-diamine, biphenylenediamine, and 4,4-diaminodiphenyl aromatic ring-containing amines such as methylmethane, 2,5-naphthylenediamine, 2,6-naphthylenediamine, reaction products of m-xylylenediamine and styrene, phenalkamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecanediamine, 1,18-octanediamine, 1,20-octanediamine, 1,21-octanediamine, 1,22-octanediamine, 1,23-octanediamine, 1,24-octanediamine, 1,25-octanediamine, 1,26-octanediamine, 1,27-octanediamine, 1,28-octanediamine, 1,29-octanediamine, 1,30-octanediamine, 1,31-octanediamine, 1,32-octanediamine, 1,33-octanediamine, 1,34-octanediamine, 1,35-octanediamine, 1,36-octanediamine, 1,37-octanediamine, 1,38-octanediamine, 1,39-octanediamine, 1,40-octanediamine, 1,41-octanediamine, 1,42-octanediamine, 1,43-octanediamine, 1,44-octanediamine, 1,45-octanediamine, 1,46-octanediamine, 1,47-octanediamine, 1,48-octanediamine, 1,4 Examples of the polyamidoamine include aliphatic amines such as decanediamine, 1,20-eicosanediamine, 2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, and 2,7-dimethyl-1,8-octanediamine, alicyclic amines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine, and polyamidoamines. Examples of the polyamidoamine include those obtained by reacting an aliphatic dicarboxylic acid such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid, or a carboxylic acid compound such as a fatty acid or dimer acid with an aliphatic polyamine or a polyamine having a polyoxyalkylene chain.

[0068] Examples of the thiol include polythiols such as dithiols and trithiols. Specific examples of the thiol include esters of polyols and mercapto organic acids, such as pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, and trimethylolpropane tris(3-mercaptobutyrate), aliphatic thiols such as alkanedithiols, and aromatic ring-containing thiols such as xylylenedithiol.

[0069] It is preferable to use amines and thiols with high molecular weights. By using amines and thiols with high molecular weights, it is possible to prevent unreacted amines and thiols from volatilizing during a thermal cycling test, thereby reducing the mass loss rate after the thermal cycling test. Therefore, even when a thermal cycling test is performed on a cured product, it is possible to prevent volatilization marks from occurring, which makes it easier to improve reliability.

[0070] Specifically, the high molecular weight amines and thiols used should have a molecular weight of 350 or more, preferably 380 or more, and more preferably 400 or more, and the upper limit of the molecular weight of the amines and thiols is not particularly limited, but is, for example, 1000 or less, preferably 800 or less, and more preferably 700 or less. The high molecular weight amines and thiols should also have a viscosity of at least a certain level, and specifically, the viscosity at 25°C should preferably be 1 Pa s or more, more preferably 3 Pa s or more, and even more preferably 5 Pa s or more, and the upper limit is not particularly limited, but from the viewpoint of lowering the viscosity of the adhesive, it should be, for example, 50 Pa s or less, preferably 30 Pa s or less, and more preferably 20 Pa s or less.

[0071] Specifically, among the above, the amines and thiols having a high molecular weight are preferably at least any one of polyoxyalkyleneamines, polyamidoamines, and esters of polyols and mercapto organic acids, and among these, polyoxyalkyleneamines are more preferred, with trimethylolpropanepoly(oxypropylene)triamine and methoxypoly(oxyethylene / oxypropylene)-2-propylamine being even more preferred.

[0072] Furthermore, when using high-molecular-weight amines and thiols, it is also preferable to use low-molecular-weight amines and thiols in combination. By using amines or thiols with different molecular weights, the epoxy group-containing compound is cured in various curing modes, and even when low-molecular-weight components are used, unreacted components are less likely to be generated. For example, a monofunctional epoxy group-containing compound with a relatively low molecular weight reacts appropriately with a low-molecular-weight fast-curing amine or thiol, while a multifunctional epoxy group-containing compound with a relatively high molecular weight reacts appropriately with a high-molecular-weight slow-curing amine or thiol, thereby allowing the curing reaction to proceed appropriately. The molecular weight of the low-molecular-weight amines and thiols is lower than that of the high-molecular-weight amines and thiols. Specifically, those with a molecular weight of less than 350, more preferably 300 or less, and even more preferably 270 or less may be used. The molecular weight of the low-molecular-weight amines and thiols is not particularly limited in its lower limit, but is, for example, 100 or more, preferably 120 or more, and more preferably 130 or more. When a high-molecular-weight amine and thiol are used in combination with a low-molecular-weight amine and thiol, adjusting the amount of the low-molecular-weight amine and thiol makes it possible to appropriately adjust the modulus of elasticity at 80°C, and also to appropriately adjust the adhesive strength, etc. Furthermore, the low-molecular-weight amine and thiol preferably have a viscosity of less than a certain value; specifically, the viscosity at 25°C is preferably less than 1 Pa·s, more preferably 500 mPa·s or less, and even more preferably 100 mPa·s or less. The lower limit is not particularly limited, but may be, for example, 1 mPa·s or more or 3 mPa·s or more from the viewpoint of reducing the viscosity of the adhesive. The molecular weights of the amine and thiol and the above-mentioned epoxy group-containing compound can be measured, for example, using a mass spectrometer (GC-MS or LC-MS).

[0073] Specifically, among the above-mentioned low-molecular-weight amines and thiols, aromatic ring-containing amines are preferred, and in particular, m-xylylenediamine and reaction products of m-xylylenediamine and styrene are preferred.

[0074] The low molecular weight amines and thiols may be, for example, 55% by mass or less, preferably 50% by mass or less, and more preferably 35% by mass or less, based on the total amount of amines and thiols contained in the adhesive. By setting the amount of low molecular weight amines and thiols to a certain level or less, it becomes easier to suppress the mass loss rate after a thermal cycling test. It also becomes easier to improve adhesive strength, etc. The low molecular weight amines and thiols may be, for example, 0% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass or more, based on the total amount of amines and thiols contained in the adhesive. By setting the amount of low molecular weight amines and thiols to a certain level or less, it becomes easier to suppress the mass loss rate after a thermal cycling test. It also becomes easier to improve adhesive strength, etc.

[0075] The active hydrogen equivalent of the amine and thiol contained in the adhesive is not particularly limited, but is, for example, 15 g / eq or more, preferably 25 g / eq or more, more preferably 30 g / eq or more, and is, for example, 250 g / eq or less, preferably 200 g / eq or less, more preferably 150 g / eq or less.

[0076] In the present invention, when an epoxy-based binder is used, it may further contain a polyfunctional acrylate compound as a main component in addition to an epoxy group-containing compound. That is, the binder may be composed of an epoxy group-containing compound as a main component and a curing agent such as an amine, or may be composed of an epoxy group-containing compound as a main component, a polyfunctional acrylate compound, and a curing agent such as an amine. The polyfunctional acrylate compounds used in combination with the epoxy group-containing compound are as follows:

[0077] (Polyfunctional acrylate compound) A polyfunctional acrylate compound is a compound having two or more functional groups (i.e., the number of (meth)acryloyl groups). Polyfunctional acrylate compounds react quickly with the above-mentioned curing agents, particularly amines, and impart a certain level of adhesive strength at the initial stage of curing. As the polyfunctional acrylate compound, it is preferable to use a polyfunctional (meth)acrylate, and it is more preferable to use an ester of a polyfunctional polyol and (meth)acrylic acid. Furthermore, in this specification, "(meth)acryloyl group" means either an acryloyl group or a methacryloyl group, "(meth)acrylate" means either an acrylate or a methacrylate, and the same applies to other similar terms.

[0078] Examples of bifunctional polyfunctional acrylate compounds include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triptyline, Examples of the di(meth)acrylate include pyrene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethylene oxide-added bisphenol A di(meth)acrylate, propylene oxide-added bisphenol A di(meth)acrylate, ethylene oxide-added bisphenol F di(meth)acrylate, dimethyloldicyclopentadienyl di(meth)acrylate, ethylene oxide-modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, carbonate diol di(meth)acrylate, polyether diol di(meth)acrylate, polyester diol di(meth)acrylate, polycaprolactone diol di(meth)acrylate, and polybutadiene diol di(meth)acrylate.

[0079] Furthermore, examples of polyfunctional acrylate compounds having three or more functional groups include trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol alkoxytetra(meth)acrylate, alkylene oxide-added trimethylolpropane tri(meth)acrylates such as ethylene oxide-added trimethylolpropane tri(meth)acrylate and propylene oxide-added trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, ethylene oxide-added trimethylolpropane tri(meth)acrylate, and propylene oxide-added trimethylolpropane tri(meth)acrylate. Examples of the alkylene oxide-added isocyanuric acid tri(meth)acrylate include hydroxyl group-added isocyanuric acid tri(meth)acrylate, propylene oxide-added glycerin tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, alkylene oxide-added pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, tripentaerythritol hepta(meth)acrylate, and tetrapentaerythritol nona(meth)acrylate.

[0080] The number of functional groups of the polyfunctional acrylate compound is preferably 3 or more, more preferably 4 or more, and even more preferably 6 or more. As the number of functional groups of the polyfunctional acrylate compound increases, the adhesive strength at the initial stage of curing tends to increase. The upper limit of the number of functional groups of the polyfunctional acrylate compound is not particularly limited, but may be, for example, 10 or less, or 8 or less.

[0081] The molecular weight of the polyfunctional acrylate compound is preferably a certain value or less, from the viewpoint of being able to reduce the viscosity of the adhesive before curing. Specific molecular weights of polyfunctional acrylate compounds may be, for example, 5,000 or less, preferably 3,000 or less, more preferably 1,000 or less, and even more preferably 700 or less. Furthermore, the molecular weight of the polyfunctional acrylate compound is, for example, 150 or more, preferably 200 or more, more preferably 250 or more, and even more preferably 450 or more. By setting the molecular weight of the polyfunctional acrylate compound to a certain value or more, it is possible to prevent the crosslinking density from becoming higher than necessary, and it is easy to improve the elongation and adhesive strength. The polyfunctional acrylate compound is preferably liquid at room temperature (25°C), from the viewpoint of being able to easily reduce the viscosity of the adhesive before curing.

[0082] The functional group equivalent of the polyfunctional acrylate compound is not particularly limited, but is preferably 500 g / eq or less, more preferably 300 g / eq or less, even more preferably 150 g / eq or less, and is preferably 75 g / eq or more, more preferably 80 g / eq or more, even more preferably 85 g / eq or more. In the adhesive, the ratio of the number of functional groups of the polyfunctional acrylate compound to the number of functional groups of the epoxy group-containing compound may be about 0.1 to 1.5, but is preferably 0.2 to 1.2, more preferably 0.3 to 1.0, even more preferably 0.4 to 0.85.

[0083] The content of the polyfunctional acrylate compound is, for example, 10% by mass or less, preferably 8% by mass or less, based on the total amount of the thermally conductive composition. Setting the content of the polyfunctional acrylate compound to the above upper limit or less prevents excessive initial curing due to the polyfunctional acrylate compound, thereby extending the usable time. Furthermore, reducing the content of the polyfunctional acrylate compound also improves moisture resistance. Therefore, for example, high adhesive strength can be maintained even when used for long periods of time under high temperature and humidity after curing. The content of the polyfunctional acrylate compound is more preferably 6% by mass or less, and even more preferably 4% by mass or less. Furthermore, in order to achieve rapid curing properties and increase adhesive strength in the early stages of curing, the content of the polyfunctional acrylate compound should be a certain amount or more, for example, 0.3% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, based on the total amount of the adhesive.

[0084] In the present invention, when an amine is used, it is preferable that one of the active hydrogen groups (N-H) constituting the amino group contributes to the curing reaction, and that a certain amount of N-H remains. This allows the adhesive to be adjusted so that the three-dimensional crosslinks in the cured product do not become too dense and the elastic modulus does not become too high. Furthermore, adjusting the amount of N-H remaining can increase the polarity of the cured product and enhance the adhesive strength with the resin. Therefore, by adjusting the amount of remaining N-H groups, the adhesive strength with the resin can be adjusted.

[0085] Similarly, when using a thiol, it is advisable to adjust the amount of S—H remaining to a certain extent. This allows the adhesive to be adjusted so that the three-dimensional crosslinks in the cured product do not become too dense and the modulus of elasticity does not become too high. Furthermore, by allowing S—H to remain, the adhesive strength to metal can be increased. When using a thiol as a curing agent, it is advisable to use it in combination with the amine, or to include at least one of a trifunctional or higher epoxy group-containing compound or a trifunctional or higher thiol. This allows the modulus of elasticity to be adjusted so that it does not become too low. Furthermore, by adjusting the amount of remaining S—H groups, the adhesive strength to metal can be adjusted.

[0086] From the viewpoint of enhancing adhesion to both resin and metal, it is preferable to use an amine and a thiol in combination so that a certain amount of active hydrogen groups (N—H and S—H) remain.

[0087] Specifically, the content of the epoxy group-containing compound and the content of the amine in the adhesive are preferably adjusted as follows: The equivalent ratio of the number of epoxy groups in the epoxy group-containing compound to the number of active hydrogen atoms in the amino groups contained in the amine [(number of active hydrogen atoms in amino groups) / number of epoxy groups] = 1.2 or more and 2.9 or less. When the equivalent ratio is 1.2 or more, even when a low-molecular-weight binder component is used, the elastic modulus is likely to be low, and the elastic modulus at 80°C can be easily adjusted to a predetermined range. Furthermore, when the equivalent ratio is 2.9 or less, the elastic modulus is prevented from being lowered more than necessary, thereby preventing a decrease in adhesive strength, etc. The equivalent ratio is more preferably 1.6 or more, even more preferably 2.0 or more, and more preferably 2.8 or less, even more preferably 2.7 or less.

[0088] Furthermore, when the adhesive contains an epoxy group-containing compound primarily composed of a difunctional epoxy group-containing compound (e.g., the proportion of difunctional epoxy group-containing compounds among all epoxy group-containing compounds is 50% by mass or more) and a trifunctional or higher polyfunctional thiol, the content of the epoxy group-containing compound and the content of the polyfunctional thiol are preferably adjusted as follows: The equivalent ratio of the number of epoxy groups in the epoxy group-containing compound to the number of active hydrogens contained in the thiol [(number of active hydrogens in thiol groups) / number of epoxy groups] = 1.3 or more and 2.6 or less. When the equivalent ratio is 1.3 or more, even when a low-molecular-weight binder component is used, the modulus of elasticity is easily reduced, making it easier to adjust the modulus of elasticity at 80°C within a predetermined range. When the equivalent ratio is 2.6 or less, the modulus of elasticity is prevented from becoming too low unnecessarily, preventing a decrease in adhesive strength, etc. The equivalent ratio is more preferably 1.35 or more, even more preferably 1.4 or more, and more preferably 2.5 or less, and even more preferably 2.25 or less.

[0089] When the adhesive contains an epoxy group-containing compound primarily composed of a trifunctional or higher polyfunctional epoxy group-containing compound (e.g., the proportion of trifunctional or higher polyfunctional epoxy group-containing compounds is 50% by mass or more of all epoxy group-containing compounds), and a bifunctional thiol, the polyfunctional epoxy group-containing compound content and the thiol content are preferably adjusted as follows: The equivalent ratio of the number of epoxy groups in the epoxy group-containing compound to the number of active hydrogens contained in the thiol [(number of active hydrogens in thiol groups) / number of epoxy groups] = 0.50 or more and 0.99 or less. By setting the equivalent ratio to 0.50 or more, the elastic modulus is prevented from becoming too low, preventing a decrease in adhesive strength, etc. Furthermore, by setting the equivalent ratio to 0.99 or less, the elastic modulus is likely to be low even when a low-molecular-weight binder component is used, and the elastic modulus at 80°C can be easily adjusted to a predetermined range. The equivalent ratio is more preferably 0.55 or more, even more preferably 0.60 or more, and is more preferably 0.95 or less, even more preferably 0.90 or less.

[0090] The above describes preferred equivalent ratios depending on the type of epoxy compound, amine, and thiol. However, even in combinations other than those described above, adjusting the equivalent ratio can prevent the elastic modulus from becoming too low more than necessary, thereby preventing a decrease in adhesive strength, etc., and can also easily reduce the elastic modulus even when a low-molecular-weight binder component is used, allowing the elastic modulus at 80°C to be adjusted to a predetermined range.

[0091] The number of epoxy groups refers to the total amount of epoxy groups contained in the adhesive, and is, for example, the value obtained by multiplying the number of epoxy groups (mol / g) per unit amount of epoxy group-containing compound contained in the adhesive by the content of the epoxy group-containing compound. However, when two or more epoxy group-containing compounds are contained, the total value is obtained by multiplying the number of epoxy groups (mol / g) per unit amount of each epoxy group-containing compound by the content of each epoxy group-containing compound. Furthermore, the number of active hydrogens of amino groups refers to the total amount of active hydrogens of amino groups contained in the adhesive, and is, for example, the value obtained by multiplying the number of active hydrogens (mol / g) per unit amount of amine in the adhesive by the content of amine. However, when two or more amines are contained, the total value is obtained by multiplying the number of active hydrogens (mol / g) per unit amount of each amine by the content of each amine. The number of active hydrogens of amines is calculated by NHR ２ is set to 1, and NH ２ In R, it is set to 2 (however, NHR ２ , N.H. ２ In R, R is a functional group other than active hydrogen, i.e., the NH or NH of an amine. ２ The number of epoxy groups per unit amount of epoxy resin (mol / g) and the number of active hydrogens per unit amount of amine (mol / g) can be calculated, for example, from the epoxy equivalent (g / eq) and the active hydrogen equivalent (g / eq), respectively. Here, the epoxy equivalent can be obtained by dividing the molecular weight of the epoxy group-containing compound by the number of epoxy groups per molecule. The active hydrogen equivalent can be obtained by dividing the molecular weight of the amine by the number of active hydrogens per molecule. The molecular weight, the number of epoxy groups, and the number of active hydrogens can be measured using a mass spectrometer (GC-MS or LC-MS). In addition, when only the molecular weight can be identified using a mass spectrometer, the number of epoxy groups and the number of active hydrogens per molecule can be determined using NMR ( １The molecular weight and the number of epoxy groups can be determined by NMR or other methods, such as H NMR. However, when the sample is a mixture, it is preferable to isolate each component by GPC (gel permeation chromatography) or HPLC (high performance liquid chromatography) before measuring NMR. When the structural formula of the epoxy group-containing compound is known, the molecular weight and the number of epoxy groups are the molecular weight and the number of epoxy groups of the epoxy group-containing compound that can be calculated from the structural formula. When the structural formula of the amine is known, the molecular weight and the number of active hydrogens are the molecular weight and the number of active hydrogens of the amine that can be calculated from the structural formula.

[0092] The number of active hydrogens in the thiol group refers to the total amount of active hydrogens in the thiol group contained in the adhesive, and is, for example, the value obtained by multiplying the number of active hydrogens per unit amount of thiol (mol / g) in the adhesive by the content of thiol.However, when two or more thiols are contained, it is the sum of the values ​​obtained by multiplying the number of active hydrogens per unit amount of each thiol (mol / g) by the content of each thiol.The number of active hydrogens in the thiol is calculated by taking SHR as 1 (where R is a functional group other than active hydrogen, that is, the part of the thiol other than the SH).In addition, when both amine and thiol are contained, the number of active hydrogens in the amino group and the thiol group is the sum of the number of active hydrogens in the amino group in the adhesive and the number of active hydrogens in the thiol group.

[0093] When a polyfunctional acrylate compound is not used, it is preferable to adjust the equivalent ratio as described above, but when an epoxy group-containing compound and a polyfunctional acrylate compound are used in combination as the main agent, it is also preferable to adjust the contents of the epoxy group-containing compound, the polyfunctional acrylate compound, and the amine in the adhesive so that the equivalent ratio of the functional groups contained in each compound is as shown in the following formula (1): [A / (B+C)]=1.1 or more and 2.9 or less (1) (Note: In formula (1), A is the number of active hydrogens in the amino groups contained in the amine compound in the adhesive, B is the number of epoxy groups contained in the epoxy resin, and C is the number of (meth)acryloyl groups contained in the acrylate compound.) When the equivalent ratio calculated by formula (1) is 1.2 or more, even when a low-molecular-weight binder component is used, the elastic modulus is likely to be low, and the elastic modulus at 80°C can be easily adjusted to a predetermined range. Furthermore, by setting the equivalent ratio calculated by the above formula (1) to 2.9 or less, the elastic modulus is prevented from becoming too low unnecessarily, thereby preventing a decrease in adhesive strength, etc. The equivalent ratio calculated by the above formula (1) is more preferably 1.6 or more, even more preferably 2.0 or more, and more preferably 2.8 or less, even more preferably 2.7 or less.

[0094] The number of epoxy groups and the number of active hydrogen atoms in the above formula (1) are as described above. The number of (meth)acryloyl groups is the total amount of (meth)acryloyl groups contained in the adhesive, and is, for example, a value obtained by multiplying the number of (meth)acryloyl groups (mol / g) per unit amount of (meth)acryloyl groups contained in the adhesive by the content of the polyfunctional acrylate compound. The number of (meth)acryloyl groups (mol / g) per unit amount of the polyfunctional acrylate compound can be calculated, for example, from the functional group equivalent (g / eq). The number of (meth)acryloyl groups can be measured using a mass spectrometer (GC-MS or LC-MS), similar to the molecular weight, number of epoxy groups, and number of active hydrogen atoms described above.

[0095] The binder content in the adhesive is preferably 8% by volume or more and 65% by volume or less, based on the total volume of the adhesive. When the binder content is above the lower limit, the thermally conductive filler can be properly dispersed in the thermally conductive member and adhesive. It is also possible to prevent the viscosity of the adhesive from becoming unnecessarily high. When the binder content is below the upper limit, it becomes easier to incorporate a certain amount of thermally conductive filler into the adhesive. The binder content in the adhesive is more preferably 15% by volume or more and 55% by volume or less, and even more preferably 18% by volume or more and 45% by volume or less.

[0096] [Thermal Conductive Filler] The adhesive of the present invention contains a thermally conductive filler. The inclusion of a thermally conductive filler in the adhesive improves the thermal conductivity of the thermally conductive member formed with the adhesive. Examples of thermally conductive fillers include metals, metal oxides, metal nitrides, metal hydroxides, carbon materials, and oxides, nitrides, and carbides other than metals. The thermally conductive filler may be spherical or in the form of an irregular powder. Examples of metals used in the thermally conductive filler include aluminum, copper, and nickel. Examples of metal oxides include aluminum oxide (e.g., alumina), magnesium oxide, and zinc oxide. Examples of metal nitrides include aluminum nitride. Examples of metal hydroxides include aluminum hydroxide. Examples of carbon materials include spherical graphite. Examples of oxides, nitrides, and carbides other than metals include quartz, boron nitride, and silicon carbide. Among these, aluminum oxide is preferred from the perspective of improving the heat dissipation properties of the thermally conductive member, and aluminum hydroxide is preferred when flame retardancy is desired. The thermally conductive filler may be used alone or in combination of two or more of the above.

[0097] The average particle size of the thermally conductive filler is preferably 0.1 μm or more and 200 μm or less, more preferably 0.5 μm or more and 150 μm or less, and even more preferably 1 μm or more and 110 μm or less. It is preferable to use a small-particle thermally conductive filler having an average particle size of 0.1 μm or more and 5 μm or less in combination with a large-particle thermally conductive filler having an average particle size of more than 5 μm and 200 μm or less. The filling rate can be increased by using thermally conductive fillers with different average particle sizes. The average particle size of the thermally conductive filler can be measured by observation using an electron microscope or the like. More specifically, for example, the particle sizes of 50 random thermally conductive fillers can be measured using an electron microscope or optical microscope, and the average particle size (arithmetic mean value) can be used.

[0098] The content of the thermally conductive filler in the adhesive is preferably 30% by volume or more and 90% by volume or less, based on the total volume of the adhesive. A content above the lower limit can impart a certain level of thermal conductivity to the adhesive. Furthermore, by setting the content of the thermally conductive filler to the upper limit or less, the thermally conductive filler can be properly dispersed in the thermally conductive member, preventing the adhesive from becoming too viscous. In the present invention, lowering the viscosity of the adhesive facilitates increasing the content of the thermally conductive filler. The content of the thermally conductive filler in the adhesive is more preferably 40% by volume or more and 80% by volume or less, and even more preferably 50% by volume or more and 75% by volume or less. The content of the thermally conductive filler in the adhesive, expressed in parts by mass, is preferably 150 parts by mass or more and 3,000 parts by mass or less, more preferably 200 parts by mass or more and 2,000 parts by mass or less, and even more preferably 300 parts by mass or more and 1,000 parts by mass or less, based on 100 parts by mass of the binder.

[0099] (Dispersant) The adhesive of the present invention may contain a dispersant. Examples of dispersants include polymeric dispersants. Examples of polymeric dispersants include polymeric compounds having functional groups. Examples of polymeric compounds include acrylic, vinyl, polyester, polyurethane, polyether, epoxy, polystyrene, amino, and silicone compounds. Examples of functional groups include carboxyl groups, phosphate groups, sulfonic acid groups, carboxylic acid ester groups, phosphate ester groups, sulfonic acid ester groups, hydroxyl groups, amino groups, quaternary ammonium bases, and amide groups. Dispersants other than polymeric dispersants may also be used, such as alkoxysilane compounds. The content of the dispersant in the adhesive is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, and even more preferably 0.4 to 3 parts by mass, per 100 parts by mass of the binder.

[0100] (Plasticizer) The adhesive of the present invention may contain a plasticizer. The inclusion of a plasticizer facilitates improving the elongation of the adhesive and reducing its viscosity, thereby improving workability. Specific examples of plasticizers include organic ester plasticizers such as monobasic organic acid esters and polybasic organic acid esters, organic phosphoric acid plasticizers such as organic phosphoric acid plasticizers and organic phosphite plasticizers, and epoxy-based plasticizers such as sulfonamides and epoxidized soybean oil. Furthermore, the plasticizer is preferably an organic ester plasticizer. Examples of the monobasic organic acid ester include glycol esters obtained by reacting glycol with a monobasic organic acid. Examples of the glycol include triethylene glycol, tetraethylene glycol, and tripropylene glycol. Examples of the monobasic organic acid include butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, heptyl acid, n-octylic acid, 2-ethylhexyl acid, n-nonylic acid, decylic acid, and benzoic acid.

[0101] Examples of the polybasic organic acid ester include ester compounds of a polybasic organic acid with an alcohol having a linear or branched structure and having 3 to 10 carbon atoms. Examples of the polybasic organic acid include adipic acid, sebacic acid, azelaic acid, and 1,2-cyclohexanedicarboxylic acid. Examples of the organic ester plasticizer include triethylene glycol di-2-ethylpropanoate, triethylene glycol di-2-ethylbutyrate, triethylene glycol di-2-ethylhexanoate, triethylene glycol dicaprylate, triethylene glycol di-n-octanoate, triethylene glycol di-n-heptanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate, dioctyl azelate, dibutyl carbitol adipate, ethylene glycol di-2-ethylbutyrate, 1,3-propylene glycol di-2-ethylbutyrate, 1,4-butylene glycol di-2-ethylbutyrate, diethylene glycol di-2-ethylbutyrate, diethylene glycol Examples of suitable organic ester plasticizers include di-2-ethylhexanoate, dipropylene glycol di-2-ethylbutyrate, triethylene glycol di-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate, diethylene glycol dicaprylate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, diisononyl 1,2-cyclohexanedicarboxylate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, a mixture of heptyl adipate and nonyl adipate, diisononyl adipate, diisodecyl adipate, heptylnonyl adipate, dibutyl sebacate, oil-modified alkyd sebacate, and a mixture of a phosphate ester and an adipate. Organic ester plasticizers other than those listed above may also be used. Adipic acid esters other than those listed above may also be used.

[0102] Examples of the organic phosphoric acid plasticizer include tributoxyethyl phosphate, isodecylphenyl phosphate, and triisopropyl phosphate. The plasticizer is preferably a diester plasticizer represented by the following formula (1) or (2): In the above formula (1), R1 and R2 each represent an organic group having 2 to 10 carbon atoms, R3 represents an ethylene group, an isopropylene group, or an n-propylene group, and p represents an integer of 3 to 10. In the above formula (1), R1 and R2 each preferably represent an organic group having 5 to 10 carbon atoms, and more preferably represent an organic group having 6 to 10 carbon atoms. In the above formula (2), R4 and R5 each represent a hydrocarbon group having 3 to 10 carbon atoms, and R6 represents a hydrocarbon group having 2 to 10 carbon atoms. In the above formula (2), R4 and R5 each preferably have 4 to 9 carbon atoms, and more preferably have 6 to 9 carbon atoms. The hydrocarbon groups of R4 and R5 are preferably alkyl groups. The alkyl group may be linear or may have a branched structure. R6 preferably has 4 to 9 carbon atoms, and more preferably has 5 to 8 carbon atoms. The hydrocarbon group of R6 is preferably an aliphatic hydrocarbon group, and among these, an unsaturated aliphatic hydrocarbon group is more preferable. R6 may be linear or may have a branched or cyclic structure, and preferably has a cyclic structure.

[0103] The plasticizer preferably includes triethylene glycol di-2-ethylhexanoate (3GO), triethylene glycol di-2-ethylbutyrate (3GH), triethylene glycol di-2-ethylpropanoate, or diisononyl 1,2-cyclohexanedicarboxylate (DINCH). The plasticizer more preferably includes triethylene glycol di-2-ethylhexanoate (3GO), triethylene glycol di-2-ethylbutyrate (3GH), or diisononyl 1,2-cyclohexanedicarboxylate (DINCH), and even more preferably includes triethylene glycol di-2-ethylhexanoate.

[0104] From the viewpoint of reducing the viscosity of the first agent, the second agent, and the composition obtained by mixing these, the molecular weight of the plasticizer is preferably less than 1,000, more preferably less than 500, and preferably 50 or more, more preferably 100 or more. Furthermore, the molecular weight of the plasticizer is preferably 50 or more and less than 1,000, more preferably 100 or more and less than 500. When the structural formula of the plasticizer is known, the molecular weight is the molecular weight calculated from the structural formula; when the structural formula is unknown, it can be measured using a mass spectrometer (GC-MS or LC-MS).

[0105] The content of the plasticizer in the adhesive is preferably 3% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 15% by mass or less, and even more preferably 7% by mass or more and 10% by mass or less, based on the total amount of the thermally conductive composition. When the amount of the plasticizer is equal to or greater than these lower limits, the viscosity of the composition can be reduced. When the amount of the plasticizer is equal to or less than these upper limits, the reliability of the adhesive can be improved.

[0106] (Other Additives) The adhesive of the present invention may contain additives other than those described above. Examples of such additives include water, which promotes the reaction between the base compound and the curing agent, curing catalysts such as bisphenol A, silanol condensation catalysts, reaction rate control agents (curing retarders) which suppress the reaction between the base compound and the curing agent, thixotropy-imparting agents, flame retardants, antioxidants, colorants, dehydrating agents, and adhesion promoters. Furthermore, it is preferable that the adhesive of the present invention does not contain a polyfunctional (meth)acrylate. By not containing a polyfunctional (meth)acrylate, an increase in crosslink density can be prevented, and the modulus of elasticity at 80°C can be reduced. When a plasticizer is used, it is preferable to use one with a high molecular weight, and it is more preferable to use a reactive plasticizer or a substantially non-volatile plasticizer.

[0107] <Supply Form> The adhesive of the present invention may be in the form of a one-component type or a two-component type consisting of a first part and a second part, but from the viewpoint of storage stability, a two-component type is preferred. In a two-component adhesive, the volume ratio of the first part to the second part (second part / first part) is preferably 1 or close to 1, specifically, preferably 0.9 or more and 1.1 or less, and more preferably 0.95 or more and 1.05 or less. In this way, by setting the volume ratio of the first part to the second part to a value of 1 or close to 1, the adhesive can be easily prepared.

[0108] Furthermore, in two-component adhesives, the first and second agents are both liquid at room temperature (25°C), and it is preferable that the viscosities of the first and second agents are the same, or even if they are different, the difference in viscosity is small. By making the viscosities of the first and second agents the same or similar, it becomes easier to mix the adhesive uniformly. Specifically, the difference in viscosity between the first agent (Pa·s) and the second agent (Pa·s) is preferably 150 Pa·s or less, more preferably 100 Pa·s or less, and even more preferably 50 Pa·s or less. Furthermore, the viscosity difference need only be 0 Pa·s or more. The viscosities of the first and second agents are not particularly limited, but are, for example, 10 Pa·s or more and 300 Pa·s or less, preferably 30 Pa·s or more and 250 Pa·s or less, and more preferably 40 Pa·s or more and 200 Pa·s or less. The viscosity of the first and second parts can be measured using a rheometer (for example, an Anton Paar MCR-302e rheometer) by adjusting the temperature of the sample to 25°C using a Peltier plate, placing the sample on a φ25 mm parallel plate, and leaving it to stand for 10 minutes, while continuously changing the shear rate within a range of 0.0001 to 100 (1 / sec). The viscosity value is measured at a shear rate of 3.16 (1 / sec).

[0109] More specifically, the two-component adhesive preferably has a first component containing a binder base and a second component containing a binder curing agent. The curing agent preferably is one that cures when mixed with the first component. The following describes in detail the structure of a two-component adhesive, taking as an example a case where the binder is an epoxy-based binder.

[0110] In two-component adhesives, the first component contains a base agent (an epoxy group-containing compound in the case of an epoxy system) but does not necessarily contain a curing agent (an amine and a thiol in the case of an epoxy system). A curing catalyst may also be included if necessary. Meanwhile, the second component contains a curing agent (an amine and a thiol in the case of an epoxy system). The second component may also be free of a curing catalyst and may also be free of a base agent (an epoxy group-containing compound in the case of an epoxy system). However, the second component may contain a base agent (an epoxy group-containing compound in the case of an epoxy system) as long as it does not react with the curing agent. Furthermore, when a polyfunctional acrylate compound is used in an epoxy system, it is preferable to include the polyfunctional acrylate compound in the first component and not include the polyfunctional acrylate compound in the second component. Furthermore, when the binder is an organic polymer having a hydrolyzable silyl group, it is preferable to include the organic polymer having a hydrolyzable silyl group in both the first component and the second component, as described above. Furthermore, when an organic polymer having a hydrolyzable silyl group is contained as a binder, it is preferable to contain a plasticizer in both the first and second parts as needed, and to contain at least one selected from a dehydrating agent, an adhesion promoter, and a silanol condensation catalyst in the first part and water in the second part.

[0111] The thermally conductive filler is contained in at least one of the first and second parts, but is preferably contained in both the first and second parts. Therefore, when the adhesive contains a base agent and a curing agent, it is preferable that the first part contains the base agent (an epoxy group-containing compound in the case of an epoxy-based adhesive) and the thermally conductive filler, and the second part contains the curing agent (at least one of an amine and a thiol in the case of an epoxy-based adhesive) and the thermally conductive filler. It is even more preferable that the first part does not contain a curing agent, and the second part does not contain a base agent. Therefore, it is even more preferable that the base agent of the adhesive is contained entirely in the first part, and the curing agent of the adhesive is contained entirely in the second part.

[0112] As described above, the thermally conductive filler is preferably contained in both the first and second parts, and more preferably in approximately equal amounts in the first and second parts. Specifically, the ratio (volume ratio) of the thermally conductive filler content in the second part to the thermally conductive filler content in the first part is preferably 0.67 to 1.5, more preferably 0.83 to 1.2, and even more preferably 0.91 to 1.1. By distributing the thermally conductive filler approximately evenly between the first and second parts, it becomes easier to reduce the viscosity difference between the first and second parts, and also to make the volume ratio of the first and second parts closer to 1.

[0113] The viscosity difference between the first and second agents can also be adjusted by adjusting the viscosity of the epoxy compound, amine, or thiol used. For example, specifically, if you want to lower the viscosity of the first agent containing an epoxy compound, you can use a low-viscosity epoxy compound or increase the content. You can also adjust the viscosity lower by adding a dispersant or plasticizer.

[0114] In addition, in order to adjust the viscosity difference and volume ratio between the first and second parts while adjusting the range of the number of epoxy groups and the equivalent ratio of active hydrogen, it is preferable to adjust the content of the thermally conductive filler and the amount of plasticizer added that does not have active hydrogen.

[0115] When the first agent contains an epoxy group-containing compound as a primary component and the second agent contains at least one of an amine or a thiol as a primary component, there may be a difference in density between the first and second agents. Mixing may be easier if the densities of the first and second agents are similar, and a smaller density difference is preferable. Specifically, the ratio of the density of the first agent to the density of the second agent (also referred to as the density ratio) is preferably 0.7 to 1.4, more preferably 0.8 to 1.2, and even more preferably 0.9 to 1.1. To reduce the density ratio, the content of the thermally conductive filler in the first and second agents may be adjusted within the above range. Incidentally, "the first agent contains an epoxy group-containing compound as a primary component" means that the first agent contains more than 50% by mass of the epoxy group-containing compound contained in the curable thermally conductive adhesive. Furthermore, the second agent containing at least one of an amine or a thiol as a main component means that the second agent contains more than 50 mass% of the amine and thiol contained in the curable thermally conductive adhesive.

[0116] In the two-component type, dispersants and other additives may be contained in one or both of the first and second components as needed. For example, when the thermally conductive filler is contained in both the first and second components, the dispersant may be contained in both the first and second components.

[0117] In two-component adhesives, the ratio of the functional group concentration (mol / g) of the second component to the functional group concentration (mol / g) of the first component is preferably 1.2 or more and 2.9 or less. By ensuring that the functional group concentrations of the first and second components are within the above range, when the first and second components are mixed at a volume ratio of 1:1, the base component and curing agent react at an appropriate equivalent ratio, allowing the adhesive to cure while maintaining appropriate adhesive strength and preventing the three-dimensional crosslinks from becoming too dense and the elastic modulus from becoming high. The functional group concentration ratio is more preferably 1.6 or more, even more preferably 2.0 or more, and more preferably 2.8 or less, even more preferably 2.7 or less.

[0118] In addition, functional group concentration refers to the concentration of functional groups contained in the main agent or curing agent that can react with the curing agent or main agent. In the case of epoxy group-containing compounds, epoxy groups are functional groups, and the number of epoxy groups per unit amount (g) is the functional group concentration. In the case of amines or thiols, active hydrogen is functional groups, and the number of active hydrogen per unit amount (g) is the functional group concentration. For example, in a preferred embodiment, the first agent contains an epoxy group-containing compound but does not contain amines or thiols, and the second agent contains either amines or thiols but does not contain epoxy group-containing compounds. In this case, the concentration of epoxy groups in the first agent is the functional group concentration of the first agent, and the concentration of active hydrogen in the amines and thiols in the second agent is the functional group concentration of the second agent.

[0119] When the adhesive is a two-component type, it is preferable that the first and second components are filled in separate containers; specifically, the first component is filled in the first container and the second component is filled in the second container. The first and second containers may be separate or integrated. By integrating the first and second containers, it becomes easier to supply the adhesive as a container set to the consumer. In this specification, the first container filled with the first component and the second container filled with the second component may be collectively referred to as a container set.

[0120] Examples of containers include, but are not limited to, syringes, cartridges, pails, drums, and the like. For example, when filling a syringe, it is preferable to use a two-liquid parallel type syringe. As shown in FIG. 1 , a two-liquid parallel type syringe 30 is an integrated device in which a first syringe 31 constituting a first container and a second syringe 32 constituting a second container are arranged in parallel. The first agent 35 and the second agent 36 filled in the syringes 31 and 32 are preferably discharged from the syringes as dispensers and mixed.

[0121] When cartridges are used, the container set comprises a first cartridge constituting the first container and a second cartridge constituting the second container, and these cartridges may be integrated. The cartridges are usually set in syringes (e.g., a first syringe and a second syringe), and the first agent delivered from the first cartridge and the second agent delivered from the second cartridge are preferably discharged from the respective outlets of the first syringe and the second syringe, using each syringe as a dispenser, and then mixed.

[0122] The first and second agents may be mixed using a mixer such as a static mixer. For example, as shown in FIG. 1 , a static mixer 38 is connected to the outlet 31A of the first syringe 31 and the outlet 32A of the second syringe 32, and the first agent 35 and the second agent 36 discharged from the outlets 31A and 32A can be mixed inside the mixer 38. The mixture (adhesive) obtained by mixing in the mixer 38 may be discharged from the outlet 39 of the mixer 38. Each syringe 31, 32 may have a structure in which the openings of barrels 33A, 34A, into which the first agent 35 and the second agent 36, respectively, are filled, are closed by lids 33B, 34B. In the syringe 30 shown in FIG. 1, the first agent 35 and the second agent 36 are preferably ejected from the respective outlets 31A and 32A after the respective lids 33B and 34B are removed and the first agent 35 and the second agent 36 are pushed out by pistons (not shown) inserted through the openings.

[0123] 2, the container set may include a first pail 41 that constitutes the first container and is filled with a first agent 45, and a second pail 42 that constitutes the second container and is filled with a second agent 46. Each pail 41, 42 may include, for example, a container body 43A, 44A that has an opening and is filled with the first agent 45 and the second agent 46, and a lid 43B, 44B that closes the opening of each container body 43A, 44A.

[0124] (Method of Preparing Adhesive) When the adhesive of the present invention is a two-component type, the first and second components may be obtained by mixing the components constituting the first and second components, respectively. Similarly, when the adhesive is a one-component type, the components constituting the adhesive may be obtained by mixing them. The method of mixing the components is not particularly limited, but for example, the adhesive may be prepared by adding a thermally conductive filler, which is blended as needed, and additives such as a dispersant, which are blended as needed, to a binder, followed by stirring or kneading.

[0125] Alternatively, the thermally conductive filler may be surface-treated with a dispersant before being mixed with a binder. By pre-surface-treating the thermally conductive filler with a dispersant, the filler is pre-surface-modified with the dispersant. The pre-surface-modified thermally conductive filler may then be mixed with a binder to prepare an adhesive. The method for pre-surface treatment using a dispersant is not particularly limited, and any known method may be used. For example, a wet treatment method, a dry treatment method, or the like may be used. In the wet treatment method, for example, a thermally conductive filler is added to and mixed with a treatment liquid in which a dispersant is dispersed or dissolved in a solvent, and then the mixture is dried, heated, washed, or the like to bond or adhere the dispersant to the surface of the thermally conductive filler. In the dry treatment method, a surface treatment is performed without using a dispersion medium. Specifically, the mixture is mixed with a dispersant and stirred in a mixer or the like, followed by heat treatment to bond or adhere the dispersant to the surface of the thermally conductive filler.

[0126] [Thermal Conductive Member] The adhesive of the present invention may be used as a thermal conductive member. The adhesive of the present invention becomes a thermal conductive member when cured. The thermal conductive member of the present invention includes a polymer matrix and a thermally conductive filler. The polymer matrix is ​​formed by curing a binder, and the thermally conductive filler is dispersed in and held by the polymer matrix. Therefore, for example, when the binder is epoxy-based, the polymer matrix is ​​formed from a cured epoxy resin.

[0127] The details of the thermally conductive filler in the thermally conductive filler are the same as those of the thermally conductive filler in the adhesive, and therefore will not be described here. The details of the binder for forming the polymer matrix are the same as those of the binder in the adhesive, and therefore will not be described here. The same applies to dispersants and other additives. However, although the binder content and the thermally conductive filler content were described above based on the volume of the entire adhesive, the thermally conductive member is formed from the adhesive, and therefore the content based on the volume of the entire adhesive described above can be considered to be the content based on the volume of the entire thermally conductive member in the thermally conductive member.

[0128] The thermally conductive member of the present invention has a mass loss rate of 1.5% or less after a thermal cycle test at −40° C. for 3 hours and at 80° C. for 3 hours, and an elastic modulus at 80° C. of 1.2×10 ８ Pa or less. By having the above configuration, the thermally conductive member of the present invention can ensure low viscosity, high thermal conductivity, and high adhesiveness while also increasing reliability. Note that the preferred numerical ranges for the mass loss rate and elastic modulus at 80°C of the thermally conductive member after a thermal cycle test are the same as the preferred numerical ranges for the mass loss rate and elastic modulus at 80°C of the cured product of the adhesive after a thermal cycle test, and therefore a description thereof will be omitted. The elastic modulus, glass transition point, and thermal conductivity of the thermally conductive member at 25°C and -40°C are also the same as those of the cured product of the adhesive, and therefore a description thereof will be omitted. Furthermore, the mass loss rate, elastic modulus, glass transition temperature, and thermal conductivity of the thermally conductive member after a thermal cycle test are measured in the same manner as those for the cured product of the adhesive, except that test samples are taken from the thermally conductive member.

[0129] [Applications] The adhesive and thermally conductive member of the present invention can be used in a variety of applications, for example, in various electronic devices such as battery assemblies such as lithium-ion battery (LiB) assemblies, power electronic devices, electronic packaging, LEDs, solar cells, and electric grids. Among these, they are preferably used in battery assemblies, and more preferably in LiB assemblies. Therefore, a preferred embodiment of the present invention provides a battery assembly including the above-described thermally conductive member. Note that battery assemblies such as LiB assemblies can be preferably used in automobiles.

[0130] In battery assembly applications, the adhesive and thermally conductive member of the present invention are preferably used as a gap filler for the battery assembly. In one aspect, the adhesive and thermally conductive member of the present invention are preferably used as a gap filler for the battery module, and more preferably as a gap filler for the battery module. An example in which the thermally conductive member of the present invention is applied to a battery module will be described below.

[0131] The battery module includes a gap material made of a thermally conductive material, a plurality of battery cells, and a module housing that houses the plurality of battery cells, the gap material being disposed inside the module housing. The gap material made of a thermally conductive material is filled between the battery cells and between the battery cells and the module housing, and the filled gap material is in close contact with the battery cells and the module housing. As a result, the gap material between the battery cells has the function of maintaining the battery cells spaced apart from each other. Furthermore, the gap material between the battery cells and the module housing is in close contact with both the battery cells and the module housing, and has the function of transferring heat generated in the battery cells to the module housing.

[0132] Fig. 3 shows a specific configuration of a battery module. Fig. 4 shows a specific configuration of each battery cell. As shown in Fig. 3, a plurality of battery cells 11 are arranged inside a battery module 10. Each battery cell 11 is laminated and enclosed in a flexible exterior film, and has an overall shape of a flat body that is thin compared to its height and width. As shown in Fig. 4, the positive electrode 11a and negative electrode 11b of such a battery cell 11 are exposed to the outside, and the central portion 11c of the flat surface is formed thicker than the crimped end portion 11d.

[0133] As shown in Fig. 3, the battery cells 11 are arranged so that their flat surfaces face each other. In the configuration of Fig. 3, the gap material 13 is not filled so as to entirely cover the plurality of battery cells 11 housed inside the module housing 12. The gap material 13 is filled so as to fill gaps that exist in a portion (bottom portion) inside the module housing 12. The gap material 13 is filled between the battery cells 11 and between the battery cells 11 and the module housing 12, and is in close contact with the surfaces of the battery cells 11 in these portions and the inner surface of the module housing 12.

[0134] The gap material 13 filled between the battery cells 11 is adhered to the surfaces of both battery cells 11. However, the gap material 13 itself has appropriate elasticity and flexibility, so that even if an external force that displaces the spacing between the battery cells 11 is applied, it can mitigate distortion and deformation due to the external force. Therefore, the gap material 13 has the function of maintaining the separation between the battery cells 11. The gap material 13 filled in the gap between the battery cell 11 and the inner surface of the module housing 12 is also tightly adhered to the surface of the battery cell 11 and the inner surface of the module housing 12. As a result, heat generated inside the battery cell 11 is conducted via the gap material 13 adhered to the surface of the battery cell 11 to the inner surface of the module housing 12, which is in close contact with the other surface of the gap material 13.

[0135] The gap material 13 can be formed in the battery module 10 by applying a liquid adhesive using a common dispenser and then curing the liquid adhesive. Furthermore, as described above, the adhesive of the present invention has low viscosity, which improves workability when forming the gap material 13. Furthermore, the gap material 13 is highly reliable, and the high thermal conductivity of the gap material 13 can be maintained for a long period of time. When forming the gap material 13, it is preferable to use a two-component adhesive, as described above. Two-component adhesives are easy to store, and if mixed immediately before use, they are less likely to harden when applied with a dispenser and can harden quickly after application. Dispenser application is also preferable because it allows the liquid adhesive to fill a relatively deep portion of the housing 12 of the battery module 10.

[0136] The gap material 13 covering the battery cells 11 preferably covers 20 to 40% of each battery cell 11 on one side of the battery cell 11. By covering 20% ​​or more, the battery cells 11 can be stably held. Furthermore, by sufficiently covering battery cells that generate a large amount of heat, heat dissipation efficiency is improved. On the other hand, by covering 40% or less, heat generated from the battery cells 11 can be efficiently dissipated, preventing weight increases and deterioration of workability. Furthermore, to improve heat dissipation efficiency, it is preferable to cover the side of the battery cells 11 where the electrodes 11a and 11b are located with the gap material 13, and it is more preferable to cover the entire electrodes 11a and 11b with the gap material 13. As described above, the battery module 10 can dissipate heat generated from the battery cells 11 to the module housing 12 via the gap material 13.

[0137] The gap material 13 is also preferably used in a battery pack having a plurality of battery modules 10 therein. A battery pack generally includes a plurality of battery modules 10 and a battery pack housing that houses the plurality of battery modules 10. In the battery pack, the gap material 13 can be provided between the battery modules 10 and the battery pack housing. This allows the heat dissipated to the module housing 12 as described above to be further dissipated to the battery pack housing, enabling effective heat dissipation.

[0138] In addition, in the above description, examples of the battery assembly have been described as a battery module or a battery pack including a battery module, but the battery assembly may also be applied to a battery assembly that does not include a battery module, and it is also preferable to apply the battery assembly to, for example, a battery assembly having a cell-to-pack structure.

[0139] FIG. 3 shows a schematic diagram of a battery assembly having a cell-to-pack structure. The battery assembly 20 having the cell-to-pack structure includes multiple battery cells 21 and a battery pack housing. The multiple battery cells 21 are bonded to a base member 25 constituting the battery pack housing via a gap member 23 made of a thermally conductive material (cured adhesive). The base member 25 may also constitute a cooling plate or the like. The adhesive of the present invention has high thermal conductivity and adhesive strength. Therefore, the gap member 23 made of the cured adhesive bonds the battery cells 21 to the base member 25 with high adhesive strength while effectively dissipating heat generated in the battery cells 21 to the base member 25. Furthermore, because the cured adhesive is highly reliable, the high thermal conductivity of the gap member 23 can be maintained for a long period of time. The gap member 23 in the battery assembly 20 may be formed in the same manner as the gap member 13 in the battery module described above, for example, using a general dispenser. The adhesive of the present invention has low viscosity, which also improves workability when forming the gap member 23.

[0140] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0141] [Elastic Modulus] The elastic modulus of the cured adhesive was measured using the following method. The adhesive was applied to the surface of a 20 cm x 20 cm silicone-based release-treated PET film using an applicator so that the adhesive would be 1 mm thick after curing. The adhesive applied to the silicone-based release-treated PET film was then left to cure for 168 hours in an environment of 25°C and 50% RH. The silicone-based release-treated PET film was then peeled off, and a test sample (cured product) measuring 30 mm x 5 mm and 1 mm thick was cut out from the resulting cured product. The obtained test sample was measured using a forced vibration type dynamic viscoelasticity measuring device ("DVA-200" manufactured by IT Measurement Control Co., Ltd.) under tensile conditions of a frequency of 10 Hz, a strain of 0.01%, a temperature range of -40°C to 100°C, and a temperature rise rate of 5°C / min. The measured values ​​of the storage modulus E' at -40°C, 25°C, and 80°C were defined as the modulus at -40°C, the modulus at 25°C, and the modulus at 80°C, respectively.

[0142] [Mass Loss Rate (%) After Thermal Cycle Test] The mass loss rate (%) of the cured adhesive product after thermal cycle test was measured using the following method. The adhesive was applied to the surface of a 20 cm x 20 cm silicone-based release-treated PET film using an applicator so that the thickness after curing was 1 mm. The adhesive applied to the silicone-based release-treated PET film was then left to cure for 168 hours in an environment of 25°C and 50% RH. The silicone-based release-treated PET film was then peeled off to obtain a 20 mm x 20 mm, 1 mm-thick test sample (cured product). The obtained test sample was subjected to 20 cycles of thermal cycle tests at -40°C and 80°C (3 hours each, 1 minute for both the temperature rise and temperature fall times). The mass of the test sample before and after the thermal cycle test was measured, and the mass loss rate was calculated using the following formula. Mass reduction rate (%) = (1 - (mass of test sample after thermal cycle test / mass of test sample after thermal cycle test)) x 100

[0143] [Glass Transition Point] The glass transition point of the cured adhesive was measured in the same manner as for the modulus of elasticity, and the temperature at which tan δ was maximized was taken as the glass transition point.

[0144] [Adhesion Test] The adhesive strength of the cured adhesive at 25°C was measured using the following method. First, two PET plates (trade name "PET-6010," manufactured by Takiron C.I. Co., Ltd.) measuring 25 mm in width, 100 mm in length, and 2 mm in thickness were prepared. An adhesive was then applied to the longitudinal end of one plate over a 5 mm length across the entire width of the plate, resulting in a thickness of 1 mm after curing. The longitudinal end of the other plate was then placed on top of the applied adhesive, and the plate was left in this state under a 25°C, 50% RH environment for 168 hours to cure the adhesive and obtain a measurement sample. The measurement sample was formed by overlapping two PET plates over their entire width by a length of 5 mm, and bonding the films together at the overlapping portion via a cured adhesive (size: 25 mm x 5 mm, thickness: 1 mm), and had a width of 25 mm and a length of 195 mm. The obtained measurement samples were subjected to a tensile test in which the measurement samples were pulled in the longitudinal direction at a tensile speed of 10 mm / sec under an environment of 25°C and 50% RH until breakage, and the maximum load was recorded as the adhesive strength. The elongation value at the maximum load was also recorded as the elongation at the maximum load. The failure mode at breakage was also observed, and in Tables 1 and 2, cohesive failure was recorded as "G" and interfacial failure as "K".

[0145] [Thermal Conductivity] The thermal conductivity of each sample was measured using a thermal diffusivity / thermal conductivity measuring device ("ai-Phase Mobile M3," manufactured by Hitachi High-Tech Corporation) to measure the thermal conductivity of the first and second adhesive components. Specifically, 2 ml of adhesive was applied to a 1 mm thick aluminum plate, which was then sandwiched between 1 mm thick glass plates to reduce the thickness to 1 mm. The adhesive was then cured at 18°C ​​for 18 hours to obtain each test sample. The resulting test samples were then subjected to 20 cycles of thermal cycling tests at -40°C and 80°C (3 hours each, with 1 minute heating and cooling times). The test samples were scanned in the range of 0.1 to 1.0 Hz before and after the thermal cycling test to obtain thermal diffusivities. This measurement was performed at 20 different locations within the test sample. The thermal conductivity was then calculated by multiplying the measured thermal diffusivity by the specific heat and density. The thermal conductivity was calculated as the average value of 20 locations, and the standard deviation was also calculated. The thermal conductivity and standard deviation obtained by the above method were evaluated according to the following criteria: A: The thermal conductivity was 1.5 W / m·K or more, and the standard deviation was 0.2 W / m·K or less. B: The thermal conductivity was 0.7 W / m·K or more but less than 1.5 W / m·K, and the standard deviation was 0.25 W / m·K or less. C: The thermal conductivity was less than 0.7 W / m·K, or the standard deviation exceeded 0.25 W / m·K.

[0146] [Viscosity] Immediately after preparation of the adhesive (immediately after mixing the first and second parts), a sample was measured using a rheometer (for example, an Anton Paar rheometer "MCR-302e"), with the sample temperature adjusted to 25°C using a Peltier plate. The sample was then placed on a φ25 mm parallel plate, and the shear rate was immediately varied continuously over a range of 0.0001 to 100 (1 / s) while the viscosity was measured. The viscosity value was measured at a shear rate of 3.16 (1 / s). For the first and second parts before mixing, the sample was placed and allowed to stand for 10 minutes, after which the viscosity was measured in the same manner.

[0147] <Evaluation> [Cold-Heat Cycle Test] 6.5 to 7.0 ml of adhesive was applied to the center of a 10 cm x 10 cm aluminum plate, 1 mm thick, without trapping any air bubbles. Then, 2 mm shim rings were placed at the four corners of the aluminum plate. Next, a glass plate (2 mm thick, 10 cm x 10 cm) was placed on top of the applied sample, and the adhesive was pressed down so that it overlapped the aluminum plate. The shim ring was secured in place with clips at the top four points. The resulting structure was left at 25°C and 50% RH for 168 hours to cure the adhesive. A test sample was obtained in which the aluminum plate and glass plate were bonded together with the cured adhesive, 2 mm thick. The resulting test sample was subjected to 20 cold-heat cycle tests at -40°C and 80°C (3 hours each, 1 minute for both the heating and cooling times). The condition of the test sample was evaluated according to the following criteria. [Evaluation Criteria] A: No peeling or volatilization marks B: Minor peeling of 10% or less of the total area or 10 or fewer volatilization marks C: Peeling of more than 10% of the total area or 11 or more volatilization marks

[0148] [Examples 1 to 15, Comparative Examples 1 to 3] First and second parts were prepared by mixing the components according to the formulations in Tables 1 and 2. The prepared first and second parts were each filled into a 50 cc two-part parallel cartridge, and mixed at a volume ratio of 1:1 at room temperature using a static mixer to obtain an adhesive. The physical properties of the obtained adhesive were determined, and evaluation tests were also carried out.

[0149] The components used in each of the examples and comparative examples were as follows. (Epoxy group-containing compounds) Resorcinol type epoxy resin (trade name "EX-201", manufactured by Nagase ChemteX Corporation), molecular weight 222, viscosity (25°C) 250 mPa·s (catalog value), epoxy equivalent 117 g / eq, number of functional groups 2, specific gravity 1.23 Phenyl glycidyl ether (trade name "Denacol EX141", manufactured by Nagase ChemteX Corporation, molecular weight 150, viscosity (25°C) 8 mPa·s (catalog value), epoxy equivalent 151 g / eq, number of functional groups 1, specific gravity 1.11, CAS. No. 122-60-1 Multifunctional epoxy resin: Bisphenol F type epoxy resin (trade name "jER806", manufactured by Mitsubishi Chemical Corporation), molecular weight 330, epoxy equivalent 165 g / eq, number of functional groups 2, viscosity (25°C) 2000 mPa·s Trimethylolpropane polyglycidyl ether (trade name "EX321", manufactured by Nagase ChemteX Corporation), molecular weight 280, viscosity (25°C) 130 Pa·s, epoxy equivalent 140 g / eq, number of functional groups 2. p-tert-butylphenyl glycidyl ether (trade name "EX146", manufactured by Nagase ChemteX Corporation), molecular weight 206, viscosity (25°C) 20 mPa·s, epoxy equivalent 255 g / eq, number of functional groups 1.

[0150] (Curing agent: amine) Trimethylolpropane poly(oxypropylene) triamine (trade name "T-403", manufactured by HUNTSMAN), molecular weight 440, viscosity (25°C) 7.0 Pa·s, active hydrogen equivalent 73.3 g / eq, amine value 291 mg KOH, functional group = 3 × (-NH ２ ), specific gravity 0.978, CAS. No. 39423-51-3 Poly(oxypropylene)diamine (trade name "D-400", manufactured by HUNTSMAN), molecular weight 430, viscosity 250 mPa·s, active hydrogen equivalent 105 g / eq, number of functional groups 2 (-NH ２ ) × 2) Phenalkamine (trade name "NC-540", manufactured by Cardolite), viscosity 2.5 Pa·s, active hydrogen equivalent 81 g / eq, amine value 490 to 550 mg KOH, specific gravity 0.99 Metaxylenediamine, molecular weight 136, viscosity (25°C) 6.8 mPa·s, active hydrogen equivalent 34 g / eq, amine value 824 mg KOH, functional group = 2 × (-NH ２), specific gravity 1.05, CAS. No. 1477-55-0, 1:1 reaction product of metaxylenediamine and styrene (trade name "GASKAMINE 240", manufactured by Mitsubishi Gas Chemical Company, Inc.), molecular weight 240, viscosity (25°C) 6.6 mPa·s, active hydrogen equivalent 80 g / eq, amine value 403 mg KOH, functional group = 1 × (-NH ２ ), 1×(-NH-), specific gravity 1.05, amidoamine (trade name "PAS151", manufactured by Ohtake Meishin Chemical Co., Ltd.), molecular weight 368, viscosity (25°C) 300 mPa·s, active hydrogen equivalent 92 g / eq, amine value 400 mg KOH, functional group = 1×(-NH ２ ) + 2 × (-NH), specific gravity 0.95 (Acrylic monomer) Pentaerythritol alkoxytetraacrylate (trade name "EBECRYL 40", manufactured by Daicel-Allnex Corporation), molecular weight 571, viscosity 160 mPa·s, acrylic equivalent 145 g / eq, number of functional groups 4 Dipentaerythritol hexaacrylate (trade name "DPHA", manufactured by Daicel-Allnex Corporation), molecular weight 520, viscosity 6.9 Pa·s, acrylic equivalent 86 g / eq, number of functional groups 6 (Urethane) Polytetramethylene ether glycol (trade name "PTMG1000", manufactured by Mitsubishi Chemical Corporation), molecular weight 1000, viscosity 320 mPa·s (40°C) Hexamethylene diisocyanate (trade name "Duranate" <Organic polymer having hydrolyzable silyl group> Kaneka Corporation's "MS Polymer SAT350", number average molecular weight 12,500, linear type, terminal silylation rate 91%, organic polymer having dimethoxymethylsilyl groups at both ends of polypropylene oxide (plasticizer) Triethylene glycol di(2-ethylhexanoate) 3GO (dispersant) Polymer-based dispersant (acidic group-containing copolymer)

[0151] <Additives> Silanol condensation catalyst: dibutyltin dilaurate, water; dehydrating agent: vinyltrimethoxysilane; adhesion promoter: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; dispersant: "DISPERBYK-106" manufactured by BYK-Chemie

[0152] (Thermal conductive filler) Aluminum hydroxide 1: irregular shape, average particle size 1 μm Aluminum hydroxide 2: irregular shape, average particle size 10 μm Aluminum hydroxide 3: irregular shape, average particle size 105 μm Aluminum hydroxide 4: irregular shape, average particle size 43 μm Aluminum oxide: spherical, average particle size 45 μm

[0153]

[0154] *The content of functional groups is the number of epoxy groups in the epoxy group-containing compound, the number of acryloyl groups, and the number of active hydrogens in the amino groups contained in the amine per unit amount (g). *The equivalent ratio is the ratio of the number of active hydrogens in the amino groups contained in the amine to the total number of epoxy groups in the epoxy group-containing compound and acryloyl groups in the acrylic monomer in the adhesive obtained by mixing the first and second parts at a volume ratio of 1:1.

[0155] The adhesives of the above examples had a mass loss rate of 1.5% or less after a thermal cycling test, and a modulus of elasticity of the cured product at 80°C of 1.2 x 10 ８ In contrast, the adhesives of the comparative examples had a mass loss rate of more than 1.5% after the thermal cycling test, or a modulus of elasticity of the cured product at 80°C of 1.2 × 10 or less. ８ Since the resistance was greater than 100 Pa, problems occurred in the thermal cycle test, and the reliability was insufficient.

[0156] DESCRIPTION OF SYMBOLS 10 Battery module 11, 21 Battery cell 12 Battery module housing (module housing) 13, 23 Gap material 20 Battery assembly 25 Base member 30 Syringe 31 First syringe 31A First syringe outlet 32 ​​Second syringe 32A Second syringe outlet 33A, 34A Barrel 33B, 34B Barrel lid 35, 45 First agent 36, 46 Second agent 38 Mixer 39 Mixer outlet 41 First pail 42 Second pail 43A, 44A Container body with opening 43B, 44B Lid for closing the opening of the container body

Claims

1. A curable thermally conductive adhesive comprising a curable binder and a thermally conductive filler, The cured product of the curable thermally conductive adhesive has a mass loss rate of 1.5% or less after a thermal cycling test in which a temperature of -40°C for 3 hours and a temperature of 80°C for 3 hours are repeated 20 times, and a modulus of elasticity at 80°C measured using a dynamic viscoelasticity measuring device is 1.2 x 10 ８ Pa or less, the binder contains at least one selected from the group consisting of urethane-based, epoxy-based, acrylic-based, and organic polymers having a hydrolyzable silyl group; A curable thermally conductive adhesive, wherein when the binder contains an epoxy system, the binder contains an epoxy group-containing compound and at least one of an amine or a thiol, and when the binder contains the amine, the equivalent ratio of the number of active hydrogens in amino groups contained in the amine to the number of epoxy groups in the epoxy group-containing compound [(number of active hydrogens in amino groups) / number of epoxy groups] is 1.36 or more and 2.9 or less.

2. The elastic modulus is 3.0×10 ６ The curable thermally conductive adhesive of claim 1 , wherein the adhesive has a viscosity of 100 Pa or more.

3. 2. The curable thermally conductive adhesive according to claim 1, having a viscosity of 300 Pa·s or less at a shear rate of 3.16 (1 / s) and 25°C as measured with a rheometer.

4. The curable thermally conductive adhesive according to claim 1 , wherein the binder comprises an epoxy group-containing compound.

5. The curable thermally conductive adhesive of claim 1 , wherein the binder comprises at least one of an amine or a thiol.

6. The curable thermally conductive adhesive according to claim 1 , wherein the binder comprises an epoxy group-containing compound and an amine.

7. 7. The curable thermally conductive adhesive according to claim 6, wherein the equivalent ratio of the number of active hydrogens of amino groups contained in the amine to the number of epoxy groups of the epoxy group-containing compound [(number of amino groups) / number of epoxy groups] is 1.36 or more and 2.9 or less.

8. 2. The curable thermally conductive adhesive according to claim 1, comprising a first part containing a main agent of the binder and filled in a first container, and a second part containing a curing agent that hardens when mixed with the first part and filled in a second container.

9. The curable thermally conductive adhesive according to claim 8 , wherein the difference in viscosity (Pa·s) between the first agent and the second agent is 150 Pa·s or less.

10. 9. The curable thermally conductive adhesive according to claim 8, wherein the ratio of the functional group concentration (mol / g) of the second agent to the functional group concentration (mol / g) of the first agent is 1.2 or more and 2.9 or less.

11. A curable thermally conductive adhesive as described in claim 1, wherein the binder includes a urethane-based binder.

12. A curable thermally conductive adhesive as described in claim 1, wherein the binder comprises an acrylic binder.

13. The curable thermally conductive adhesive of claim 1, wherein the binder comprises an organic polymer having a hydrolyzable silyl group.

14. A container set containing the curable thermally conductive adhesive according to any one of claims 8 to 13, comprising a first container containing the first part and a second container containing the second part.

15. a polymer matrix and a thermally conductive filler; The mass loss rate after a thermal cycling test in which 3 hours at -40°C and 3 hours at 80°C are repeated 20 times is 1.5% or less, and the modulus of elasticity at 80°C measured using a dynamic viscoelasticity measuring device is 1.2 × 10 ８ Pa or less, the polymer matrix contains at least one selected from the group consisting of a cured urethane resin, a cured epoxy resin, a cured acrylic resin, and a cured organic polymer having a hydrolyzable silyl group; A thermally conductive member, wherein when the polymer matrix contains a cured epoxy resin, the polymer matrix contains an epoxy group-containing compound and at least one of an amine or a thiol, and when the polymer matrix contains the amine, the equivalent ratio of the number of active hydrogens in amino groups contained in the amine to the number of epoxy groups in the epoxy group-containing compound [(number of active hydrogens in amino groups) / number of epoxy groups] is 1.36 or more and 2.9 or less.

16. A thermally conductive member comprising a cured product of the curable thermally conductive adhesive according to claim 1.

17. A battery assembly comprising the thermally conductive member according to claim 15 or 16.