Thermally conductive composition, thermally conductive member, and battery assembly

Abstract

A thermally conductive composition according to the present invention contains an organic polymer having a hydrolyzable silyl group, a non-reactive component, and a thermally conductive filler. The thermally conductive filler contains aluminum oxide. The content of the aluminum oxide is 10 vol% or more of the total volume of the thermally conductive composition. The surface area of the aluminum oxide with respect to 1 g of the thermally conductive composition is 0.07 m2 or less. The sum of X represented by formula (1) calculated on the basis of the polarity term δP of the Hansen solubility parameter of the non-reactive component is 1.5 or less.　The present invention makes it possible to provide a thermally conductive composition that contains an organic polymer having a hydrolyzable silyl group and that has excellent heat dissipation properties and a low dielectric constant. Formula (1): X=polarity term δP of Hansen solubility parameter of non-reactive component × volume of non-reactive component contained in thermally conductive composition / volume of liquid contained in thermally conductive composition

Description

Thermally conductive composition, thermally conductive member, and battery assembly

[0001] The present invention relates to a thermally conductive composition, a thermally conductive member, and a battery assembly.

[0002] Thermally conductive compositions containing thermally conductive fillers are widely known as curable liquid compositions. For example, they are filled between a heat generating element and a heat sink, and then cured to form a cured product, which is used as a thermally conductive member such as a heat dissipating gap filler that transfers heat generated by the heat generating element to the heat sink.

[0003] In recent years, amid a market backdrop of steady growth in the production volume of electric vehicles (EVs), there has been an increasing demand for two-component, room-temperature curing heat-dissipating gap fillers for lithium-ion batteries (LiBs). From the viewpoint of heat dissipation, in lithium-ion batteries, thermally conductive compositions are often filled between components such as battery cells, battery modules, and battery packs to fix the components together and to enhance heat dissipation.

[0004] In order to further popularize EVs and continue sustainable development while preserving the global environment, reducing EV manufacturing costs and waste generated during the EV manufacturing process are major challenges. There is a strong demand for battery pack designs that facilitate recycling and rework (touch-up and repair) in order to improve manufacturing efficiency and reduce waste. One solution to this problem is to use a composition containing an organic polymer having a hydrolyzable silyl group and a thermally conductive filler, as described in Patent Document 1, as a heat-dissipating gap filler. To reduce the weight of EV bodies, it is preferable for the thermally conductive filler used in heat-dissipating gap fillers to have a low specific gravity. Therefore, the technology of using low-specific-gravity fillers, such as aluminum hydroxide, is extremely important.

[0005] On the other hand, in order to ensure heat dissipation, it is desirable to use a thermally conductive filler such as aluminum oxide, which has high thermal conductivity. For example, Patent Document 2 describes a thermally conductive curable composition containing a first part and a second part, which contains a silyl-modified reactive polymer and a ceramic filler mixture, and describes that it is preferable to use aluminum oxide (alumina), which has high thermal conductivity, as the ceramic filler mixture.

[0006] International Publication No. 2023-190722 Special Publication No. 2022-521790

[0007] As mentioned above, Patent Document 2 describes that it is preferable to use alumina with high thermal conductivity. However, cured products of compositions containing alumina tend to have high dielectric constants, leaving room for improvement. Heat dissipation materials used in electric vehicles and the like are required to have low dielectric constants, and using heat dissipation materials with high dielectric constants can cause static electricity, which can cause discomfort and malfunction of electronic functions. Furthermore, heat dissipation materials generally achieve the desired performance by combining multiple liquid components with thermally conductive fillers. In particular, liquid components such as plasticizers (diluents) that are not incorporated into the reaction system after the curing reaction tend to increase the dielectric constant, and no materials have been reported to date that combine heat dissipation and low dielectric constant.

[0008] Therefore, an object of the present invention is to provide a thermally conductive composition containing an organic polymer having a hydrolyzable silyl group, which has excellent heat dissipation properties and a low dielectric constant.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that the above-mentioned problems can be solved by including an organic polymer having a hydrolyzable silyl group, a non-reactive component, and aluminum oxide, wherein the content and surface area of ​​the aluminum oxide are within specific ranges, and X, which is calculated based on the polar term δP of the Hansen solubility parameter of the non-reactive component, in formula (1) is set to a certain value or less, and have completed the present invention. The present invention provides the following [1] to

[12] .

[0010] [1] A thermally conductive composition comprising an organic polymer having a hydrolyzable silyl group, a non-reactive component, and a thermally conductive filler, wherein the thermally conductive filler contains aluminum oxide, the content of the aluminum oxide is 10% by volume or more of the total volume of the thermally conductive composition, and the surface area of ​​the aluminum oxide per 1 g of the thermally conductive composition is 0.07 m ２ A thermally conductive composition, wherein the sum of X's expressed by formula (1), calculated based on the polar term δP of the Hansen solubility parameter of the non-reactive component, is 1.5 or less. X = polar term δP of the Hansen solubility parameter of the non-reactive component × volume of the non-reactive component contained in the thermally conductive composition / volume of the liquid component contained in the thermally conductive composition Formula (1) [2] The thermally conductive composition according to the above [1], wherein the organic polymer having a hydrolyzable silyl group has a main chain consisting of a polyether skeleton. [3] The thermally conductive composition according to the above [1] or [2], wherein the thermally conductive filler contains aluminum hydroxide. [4] The thermally conductive composition according to any of the above [1] to [3], wherein the non-reactive component contains a plasticizer. [5] The thermally conductive composition according to any of the above [1] to [4], wherein the thermally conductive composition is a two-component curing type composed of a first part filled in a first container and a second part filled in a second container. [6] The thermally conductive composition according to [5] above, wherein the first agent contains a plasticizer, a thermally conductive filler, and a silanol catalyst. [7] The thermally conductive composition according to [5] or [6] above, wherein the first agent does not contain an organic polymer having a hydrolyzable silyl group. [8] The thermally conductive composition according to any one of [5] to [7] above, wherein the second agent contains an organic polymer having a hydrolyzable silyl group, a plasticizer, a thermally conductive filler, and water. [9] The thermally conductive composition according to any one of [5] to [8] above, wherein the second agent contains a compatibilizer.

[10] A thermally conductive member comprising a cured product of the thermally conductive composition according to any one of [1] to [9] above.

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

[10] above.

[12] Use of the thermally conductive member according to

[10] above as a heat dissipation material for a battery assembly.

[0011] According to the present invention, it is possible to provide a thermally conductive composition that contains an organic polymer having a hydrolyzable silyl group, and that has excellent heat dissipation properties and a low dielectric constant.

[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; FIG. 4 is a perspective view showing a typical configuration of a battery cell; FIG. 5 is a perspective view showing a battery assembly having a cell-to-pack structure;

[0013] [Thermal Conductive Composition] The thermal conductive composition of the present invention is a thermal conductive composition comprising an organic polymer having a hydrolyzable silyl group, a non-reactive component, and a thermally conductive filler. The thermally conductive filler contains aluminum oxide, the content of the aluminum oxide is 10% by volume or more of the total volume of the thermally conductive composition, and the surface area of ​​the aluminum oxide per 1 g of the thermally conductive composition is 0.07 m ２ Furthermore, the sum of X's expressed by the following formula (1), calculated based on the polarity term δP of the Hansen solubility parameter of the non-reactive component, is 1.5 or less: X = polarity term δP of the Hansen solubility parameter of the non-reactive component × volume of the non-reactive component contained in the thermally conductive composition / volume of the liquid content contained in the thermally conductive composition Formula (1)

[0014] The thermally conductive composition of the present invention may be used as a one-component type or a two-component type, as will be described in detail later. The two-component type is composed of a first component and a second component, which are mixed together when used.

[0015] <Organic Polymer Having Hydrolyzable Silyl Groups> The thermally conductive composition of the present invention contains an organic polymer having hydrolyzable silyl groups. The hydrolyzable silyl groups contained in the organic polymer are hydrolyzed by moisture, such as humidity, to form silanol groups, which can then undergo condensation polymerization to form siloxane bonds between the silanol groups or between the silanol groups and the hydrolyzable silyl groups. This allows the organic polymer to form a crosslinked structure and harden, resulting in a rubber-like elastomer. Note that a silanol group refers to a hydroxy group (Si—OH) directly bonded to a silicon atom. When the thermally conductive composition of the present invention is a two-component composition, as described below, the organic polymer having hydrolyzable silyl groups can be contained in one or both of the first and second components. However, it is preferable to contain the organic polymer in the second component rather than the first component.

[0016] 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.

[0017] 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.

[0018] 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 thermally conductive composition. The terminal silylation rate means 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.

[0019] The average number of hydrolyzable silyl groups in one molecule of the 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 curability and elongation of the thermally conductive composition are improved. The average number of hydrolyzable silyl groups in one molecule of the 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.

[0020] 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.

[0021] 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; polyurethanes; 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 acetate, 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.

[0022] Among these, polyalkylene oxides are preferred as organic polymers from the viewpoint of improving adhesive strength and elongation after curing. In the case of polyalkylene oxides, the organic polymer has a main chain consisting of a polyether skeleton. As the organic polymer having a hydrolyzable silyl group, polyalkylene oxides having a hydrolyzable silyl group are preferred. Among polyalkylene oxides, polypropylene oxide is particularly preferred.

[0023] The number-average molecular weight (Mn) of the organic polymer containing hydrolyzable silyl groups is preferably 1,000 to 70,000, more preferably 3,000 to 40,000, and even more preferably 5,000 to 30,000. When the number-average molecular weight of the organic polymer containing hydrolyzable silyl groups is below these upper limits, the viscosity of the resulting thermally conductive composition is reduced, improving coatability. Furthermore, when the number-average molecular weight of the organic polymer containing hydrolyzable silyl groups is above these lower limits, the cured product of the thermally conductive composition is prevented from becoming brittle, improving the hardness and elongation of the cured product. Note that when the adhesive composition 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 the organic polymers.

[0024] 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.

[0025] 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," "S327," "SAT350," "SAX010," and "SAX220."

[0026] <Non-reactive component> The thermally conductive composition of the present invention contains a non-reactive component. The non-reactive component is a component that does not react with an organic polymer having a hydrolyzable silyl group. Note that thermally conductive fillers and catalysts are not considered to be non-reactive components. The non-reactive component is a compound that does not contain an alkoxy group, and for example, the plasticizers and compatibilizers described below are considered to be non-reactive components. By adding the non-reactive component, it is possible to adjust the physical properties such as flexibility and elongation of the thermally conductive member, which is a cured product of the thermally conductive composition.

[0027] (Hansen Solubility Parameter) In the present invention, the sum of Xs represented by formula (1), calculated based on the polarity term δP of the Hansen solubility parameters of the non-reactive components, is 1.5 or less. If X exceeds 1.5, the dielectric constant of the thermally conductive member, which is a cured product of the thermally conductive composition, increases. Therefore, when the thermally conductive member is used as a heat dissipation material, static electricity may be generated, causing discomfort and malfunction of electronic functions. From the viewpoint of reducing the dielectric constant, the sum of Xs represented by formula (1), calculated based on the polarity term δP of the Hansen solubility parameters of the non-reactive components, is 1.5 or less, preferably 1.2 or less, and more preferably 1.0 or less. Note that the lower limit of the sum of Xs is not particularly limited, but is, for example, 0.5, from the viewpoint of blending a certain amount or more of the non-reactive components and adjusting the thermally conductive composition to the desired physical properties. Examples of means for adjusting the sum of X's represented by formula (1) to a value below a certain level include using a non-reactive component with a low polarity term δP of the Hansen solubility parameter of the non-reactive component, or appropriately adjusting the blending amount of the non-reactive component. Specifically, as a non-reactive component with a low polarity term δP of the Hansen solubility parameter, it is preferable to use a non-reactive component with a chemical structure that contains few or no highly polar functional groups such as hydroxyl groups, amino groups, carboxy groups, and amide groups. Furthermore, when mixing a non-reactive component with low polarity and a non-reactive component with high polarity, the overall polarity term value can be adjusted to a predetermined value or below by adjusting the ratio.

[0028] X can be calculated by the following formula (1): X = polar term δP of the Hansen solubility parameter of the non-reactive component × volume of the non-reactive component contained in the thermal conductive composition / volume of the liquid component contained in the thermal conductive composition Formula (1) The unit of the polar term δP of the Hansen solubility parameter is [(MPa / cm ３ ) １／２ ]. The sum of X means that, when a plurality of non-reactive components are contained, X is calculated for each non-reactive component based on formula (1) and the X of all non-reactive components is added together. When there is only one non-reactive component, X is calculated for that one non-reactive component based on formula (1), and this X becomes the sum of X. Furthermore, when there are two non-reactive components, for example, the sum of X can be calculated as follows: X1 = polar term δP of Hansen solubility parameter of first non-reactive component × volume of first non-reactive component contained in thermal conductive composition / volume of liquid contained in thermal conductive composition Formula (2) X2 = polar term δP of Hansen solubility parameter of second non-reactive component × volume of second non-reactive component contained in thermal conductive composition / volume of liquid contained in thermal conductive composition Formula (3) Sum of X = X1 + X2 (Formula 4)

[0029] The Hansen solubility parameter represents solubility in a three-dimensional space consisting of a dispersion term, a polar term, and a hydrogen bonding term. The dispersion term indicates the effect of dispersion forces, the polar term indicates the effect of dipole-dipole forces, and the hydrogen bonding term indicates the effect of hydrogen bonding forces. The definition and calculation of the Hansen solubility parameter are described in "Hansen Solubility Parameters: A Users Handbook" by Charles M. Hansen (CRC Press, 2007). The Hansen solubility parameter can also be easily estimated using the computer software Hansen Solubility Parameters in Practice (HSPiP). Details of the method for calculating the "polar term δP of the Hansen solubility parameter of the non-reactive component" in Equation (1) are described in the Examples.

[0030] In formula (1), the volume of the non-reactive component is determined by the amount (g) of the non-reactive component and the specific gravity (g / cm ３) In addition, when there are multiple non-reactive components, X is calculated for each non-reactive component based on formula (1), and the sum of X for all non-reactive components is calculated, which is the X represented by formula (1) of the non-reactive component of the present invention. In formula (1), the volume of the liquid component is calculated based on the amount (g) of the liquid component and the specific gravity (g / cm ３ ) is calculated. When there are multiple liquid components, the sum of the volumes of the multiple liquid components corresponds to the volume of the liquid component in formula (1). The liquid component refers to components other than solid components such as thermally conductive fillers. The liquid component usually indicates the properties of a liquid at room temperature (25°C). In the present invention, organic polymers having a hydrolyzable silyl group, plasticizers, compatibilizers, adhesion modifiers, dehydrating agents, catalysts, and water are considered to be liquid components.

[0031] (Plasticizer) The thermally conductive composition of the present invention preferably contains a plasticizer as a non-reactive component. By containing a plasticizer, the flexibility and elongation of the cured product can be improved. In addition, the viscosity is likely to be reduced, improving workability. When the thermally conductive composition of the present invention is a two-component composition described below, the plasticizer can be contained in one or both of the first and second components, but it is preferable to contain the plasticizer in both the first and second components.

[0032] Specific examples of plasticizers include organic ester plasticizers such as monobasic organic acid esters and polybasic organic acid esters, organic phosphorus-based plasticizers such as organic phosphate plasticizers and organic phosphite plasticizers, and epoxy-based plasticizers such as sulfonamides and epoxidized soybean oil. Furthermore, organic ester plasticizers are preferred from the viewpoint of excellent compatibility with organic polymers having hydrolyzable silyl groups. Among these, organic ester plasticizers and epoxy-based plasticizers are preferred from the viewpoint of maintaining the polarity term δP of the Hansen solubility parameter at a predetermined value or less. Examples of the monobasic organic acid esters include glycol esters obtained by reacting glycol with a monobasic organic acid. Examples of glycols include triethylene glycol, tetraethylene glycol, and tripropylene glycol. Examples of the monobasic organic acids 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.

[0033] Examples of the polybasic organic acid ester include ester compounds of polybasic organic acids with alcohols having a linear or branched structure and 4 to 8 carbon atoms. Examples of the polybasic organic acids include adipic acid, sebacic acid, and azelaic 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, and diethylene glycol di-2-ethylbutylene. Examples of suitable organic ester plasticizers include ethylene glycol 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, 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 these may also be used. Adipic acid esters other than the above-mentioned adipic acid esters may also be used.

[0034] Examples of the organic phosphoric acid plasticizer include tributoxyethyl phosphate, isodecylphenyl phosphate, and triisopropyl phosphate.

[0035] The plasticizer is preferably a diester plasticizer represented by the following formula (5) or (6). In the above formula (5), 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 (5), 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 (6), 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 (6), 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.

[0036] The plasticizer preferably includes triethylene glycol di-2-ethylhexanoate (3GO), diisononyl 1,2-cyclohexanedicarboxylate (DINCH), diisononyl adipate (DINA), triethylene glycol di-2-ethylbutyrate (3GH), or triethylene glycol di-2-ethylpropanoate. 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 or diisononyl 1,2-cyclohexanedicarboxylate. Among these, from the viewpoint of satisfying the above formula (1) and reducing the dielectric constant, the plasticizer preferably includes diisononyl adipate (DINA) or 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH), and particularly preferably includes 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH). This is because these plasticizers have a relatively small polarity term δP of the Hansen solubility parameter. The total amount of these plasticizers, i.e., one or more plasticizers selected from diisononyl adipate (DINA) and 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH), is preferably 50% by mass or more of the total amount of plasticizers, and more preferably 100% by mass (i.e., the total amount of plasticizers is composed of the above).

[0037] From the viewpoint of reducing the viscosity of the composition, 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 a molecular weight calculated from the structural formula. When the structural formula is unknown, the molecular weight can be measured using a mass spectrometer (GC-MS or LC-MS).

[0038] The content of the plasticizer in the thermally conductive composition is preferably 10 to 200 parts by mass, more preferably 20 to 150 parts by mass, and even more preferably 50 to 120 parts by mass, per 100 parts by mass of the organic polymer having a hydrolyzable silyl group. When the amount of plasticizer is equal to or greater than these lower limits, flexibility and elongation are improved, and workability is also improved. When the amount of plasticizer is equal to or less than these upper limits, the dielectric constant tends to decrease. This is because the plasticizer often has a higher polarity than the organic polymer having a hydrolyzable silyl group, and by appropriately adjusting the amount of plasticizer, the polarity term δP of the overall Hansen solubility parameter can be easily reduced.

[0039] (Compatibilizer) The thermally conductive composition of the present invention may contain a compatibilizer as a non-reactive component. By containing a compatibilizer, for example, the dispersibility in water is improved and thickening of the composition is suppressed. Note that when the thermally conductive composition of the present invention is a two-component composition described below, it is preferable to contain the compatibilizer in the second component from the viewpoint of storage stability.

[0040] As the compatibilizer, a compound having a hydroxyl group is preferred, and among them, a glycol ether having one hydroxyl group is preferred from the viewpoint of keeping the sum of X represented by the above formula (1) below a certain value and reducing the dielectric constant. This is because compounds having many hydroxyl groups have a relatively large value of the polar term δP of the Hansen solubility parameter, which may increase the value of the polar term δP of the overall Hansen solubility parameter. A glycol ether having one hydroxyl group is a compound in which the hydrogen atom of one of the two hydroxyl groups at both ends of an alkylene glycol is substituted with an alkyl group, or a compound in which the hydrogen atom of one of the two hydroxyl groups at both ends of a polyalkylene glycol is substituted with an alkyl group.

[0041] The glycol ether having one hydroxyl group is preferably a compound represented by the following formula (a): In formula (a), R7 is an alkylene group having 2 to 4 carbon atoms, and R ８ is an alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 4. From the viewpoint of suppressing the increase in viscosity of the thermally conductive composition and facilitating adjustment of the dielectric constant to a low level, R７ is preferably an alkylene group having 2 or 3 carbon atoms, and more preferably an alkylene group having 2 carbon atoms (i.e., an ethylene group). ８ is preferably an alkyl group having 2 to 6 carbon atoms, more preferably an alkyl group having 3 to 4 carbon atoms, and even more preferably a butyl group. Also, n is preferably an integer of 1 to 3, and more preferably 2.

[0042] Examples of glycol ethers having one hydroxyl group include methyl carbitol, methoxy triglycol, carbitol, ethoxy triglycol, butyl cellosolve, butyl carbitol, ethylene glycol mono-t-butyl ether, butoxy triglycol, hexyl cellosolve, hexyl carbitol, propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, etc. Among these, butyl carbitol and ethylene glycol mono-t-butyl ether are more preferred, and butyl carbitol is most preferred.

[0043] It is preferable that the thermally conductive composition does not contain a compatibilizer, but if the thermally conductive composition contains a compatibilizer, the content of the compatibilizer is preferably less than the content of the plasticizer, and the content of the compatibilizer is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the organic polymer having a hydrolyzable silyl group. This is because adjusting the content of the compatibilizer to be low makes it easier to keep the sum of X in equation (1), calculated based on the value of the polar term δP of the Hansen solubility parameter, below a predetermined value.

[0044] <Aluminum Oxide> The thermally conductive composition of the present invention contains a thermally conductive filler containing aluminum oxide. Aluminum oxide has high thermal conductivity, which improves the heat dissipation properties of the thermally conductive composition. The content of aluminum oxide is 10 vol% or more, preferably 11 vol% or more, more preferably 12 vol% or more, and preferably 30 vol% or less, more preferably 25 vol% or less, and even more preferably 20 vol% or less, based on the total volume of the thermally conductive composition. When the content of aluminum oxide is equal to or greater than these lower limits, the heat dissipation properties are improved, and when the content of aluminum oxide is equal to or less than these upper limits, the dielectric constant can be easily adjusted to a low value.

[0045] The surface area of ​​aluminum oxide per 1 g of thermally conductive composition is 0.07 m ２ The surface area of ​​the aluminum oxide is 0.07 m or less. ２ If the solubility is greater than 1 / 2, the dielectric constant of the thermally conductive member, which is a cured product of the thermally conductive composition, will be high. Therefore, when the thermally conductive member is used as a heat dissipation material, charging may occur, resulting in discomfort due to static electricity and malfunction of electronic functions. In the present invention, it is important to simultaneously reduce the surface area of ​​aluminum oxide to a certain level and reduce the polarity term δP of the Hansen solubility parameter of the non-reactive component described above in order to reduce the dielectric constant. The reason for this is presumed to be as follows. That is, non-reactive components with high polarity have high wettability with aluminum oxide and tend to localize on the aluminum oxide surface. Therefore, if both the polarity term δP of the non-reactive component and the surface area of ​​aluminum oxide become large, there is a concern that the dielectric constant will deteriorate exponentially. Furthermore, reducing only one of the polarity term δP of the non-reactive component or the surface area of ​​aluminum oxide has limited effect on reducing the dielectric constant. Therefore, reducing both the polarity term δP of the non-reactive component and the surface area of ​​aluminum oxide to a predetermined level or less is effective in reducing the dielectric constant. From the viewpoint of reducing the dielectric constant, the surface area of ​​aluminum oxide per 1 g of the thermally conductive composition is preferably 0.06 m. ２ More preferably, it is 0.05 m or less. ２The surface area of ​​aluminum oxide per 1 g of the thermally conductive composition is preferably 0.01 m or less from the viewpoint of improving the extensibility of the cured product. ２ The surface area of ​​aluminum oxide per 1 g of thermally conductive composition can be calculated by the following formula: Surface area of ​​aluminum oxide per 1 g of thermally conductive composition = (amount of aluminum oxide (g) × specific surface area of ​​aluminum oxide (m ２ / g)) / amount (g) of thermally conductive composition. In the above formula, the specific surface area is measured by the BET method. The surface area of ​​aluminum oxide can be adjusted as follows. That is, the surface area can be adjusted to a predetermined level or less by using aluminum oxide with a relatively large particle size and reducing the amount of aluminum oxide with a small particle size, selecting aluminum oxide with a shape that is closer to spherical rather than flat, fibrous, or crushed, or selecting aluminum oxide with high crystallinity and minimal surface irregularities.

[0046] One type of aluminum oxide may be used alone, or two or more types may be used in combination. For example, it is preferable to use two or more types of aluminum oxide with different average particle sizes in combination. This facilitates improving the fillability of the aluminum oxide into the composition. The aluminum oxide preferably contains small-particle aluminum oxide with an average particle size of 1 μm or more and 20 μm or less. The inclusion of small-particle aluminum oxide facilitates improving the elongation of the thermally conductive member, which is the cured product of the thermally conductive composition, and improves its ability to conform to the adherend. Furthermore, when two or more types of aluminum oxide with different average particle sizes are blended, it is preferable to use a small-particle aluminum oxide with an average particle size of 1 μm or more and 20 μm or less in combination with a large-particle aluminum oxide with an average particle size of more than 20 μm and 200 μm or less. In this specification, the average particle size is the median diameter (D50) measured using a laser diffraction / scattering particle size distribution analyzer. In the thermally conductive composition, the ratio of the content of large-particle size aluminum oxide to the content of small-particle size aluminum oxide (content of large-particle size alumina / content of small-particle size alumina) is preferably 0.1 to 10, more preferably 0.5 to 5, and even more preferably 1 to 2.5.

[0047] <Aluminum hydroxide> The thermally conductive filler in the thermally conductive composition of the present invention preferably contains aluminum hydroxide in addition to the aluminum oxide described above. By using aluminum oxide and aluminum hydroxide in combination, it becomes easier to adjust the dielectric constant low while improving heat dissipation. Furthermore, because aluminum hydroxide has a small specific gravity, it becomes easier to reduce the weight of the thermally conductive member obtained by curing the thermally conductive composition, and of a battery assembly or the like that includes the thermally conductive member.

[0048] The aluminum hydroxide preferably contains small-particle aluminum hydroxide having an average particle size of 5 μm or less. The inclusion of this small-particle aluminum hydroxide tends to improve the elongation of the thermally conductive member, resulting in good conformability to the adherend. Furthermore, when the small-particle aluminum hydroxide is used in combination with the large-particle aluminum hydroxide described below, for example, the overall filling rate of the aluminum hydroxide in the composition tends to be increased. The average particle size of the small-particle aluminum hydroxide is preferably 0.1 μm or more and 5 μm or less, more preferably 0.2 μm or more and 3 μm or less, and even more preferably 0.5 μm or more and 2 μm or less.

[0049] The aluminum hydroxide preferably contains both the small particle size aluminum hydroxide and the large particle size aluminum hydroxide described above. This allows the aluminum hydroxide loading rate in the composition to be increased, making it easier to improve heat dissipation. The average particle size of the large particle size aluminum hydroxide is greater than 5 μm, preferably 10 μm or more and 200 μm or less. In the thermally conductive composition, the ratio of the content of the large particle size aluminum hydroxide to the content of the small particle size aluminum hydroxide (content of large particle size aluminum hydroxide / content of small particle size aluminum hydroxide) is preferably 0.5 to 20, more preferably 1 to 15, and even more preferably 1.5 to 10.

[0050] The content of aluminum hydroxide in the thermally conductive composition is preferably 10 to 80% by volume, more preferably 20 to 70% by volume, and even more preferably 30 to 60% by volume, from the viewpoints of improving heat dissipation and ease of handling.

[0051] <Other Thermally Conductive Fillers> The thermally conductive composition of the present invention may contain other thermally conductive fillers in addition to the aluminum oxide and aluminum hydroxide described above. Examples of other thermally conductive fillers include metals, metal oxides, metal nitrides, carbon materials, and oxides, nitrides, and carbides other than metals. Examples of metals include aluminum, copper, and nickel. Examples of metal oxides include magnesium oxide and zinc oxide. Examples of metal nitrides include aluminum nitride. Furthermore, examples of carbon materials include spherical graphite. Examples of oxides, nitrides, and carbides other than metals include quartz, boron nitride, and silicon carbide.

[0052] The content of the thermally conductive filler in the thermally conductive composition of the present invention (the content of all thermally conductive fillers) is preferably 20 to 90% by volume, more preferably 30 to 85% by volume, and even more preferably 50 to 75% by volume.

[0053] <Water> The thermally conductive composition of the present invention preferably contains water. By including water, the thermally conductive composition can be cured by a condensation reaction of the organic polymer. When the thermally conductive composition of the present invention is a two-component composition as described below, water is preferably contained in the second part. The content of water is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the organic polymer having a hydrolyzable silyl group.

[0054] <Silanol condensation catalyst> The thermally conductive composition of the present invention preferably contains a silanol condensation catalyst. The silanol condensation catalyst causes a condensation reaction of the organic polymer to form a cured product. When the thermally conductive composition of the present invention is a two-component composition as described below, the silanol condensation catalyst is preferably contained in the first component from the viewpoint of storage stability.

[0055] Examples of silanol condensation catalysts include organotin compounds such as dibutyltin dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin phthalate, bis(dibutyltin laurate)oxide, dibutyltin bis(acetylacetonate), dibutyltin bis(monoester maleate), tin octoate, dibutyltin octoate, dioctyltin oxide, dioctyltin diversatate, dioctyltin distearate, dibutyltin bis(triethoxysilicate), bis(dibutyltin bistriethoxysilicate)oxide, dibutyltin oxybisethoxysilicate, and 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distannoxane, and organotitanium compounds such as tetra-n-butoxytitanate and tetraisopropoxytitanate. These silanol condensation catalysts may be used alone or in combination of two or more. Of the above-mentioned silanol condensation catalysts, organotin compounds are preferred, and dibutyltin dilaurate is more preferred.

[0056] The content of the silanol condensation catalyst in the thermally conductive composition is preferably 1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the organic polymer containing a hydrolyzable silyl group. When the content of the silanol condensation catalyst is equal to or greater than these lower limits, the curing rate can be increased, and when the content of the silanol condensation catalyst is equal to or less than these upper limits, a decrease in the storage stability of the composition can be suppressed.

[0057] <Adhesion Promoter> The thermally conductive composition of the present invention preferably contains an adhesion promoter. The adhesion promoter can further improve the adhesiveness of a cured product of the thermally conductive composition. When the thermally conductive composition of the present invention is a two-component composition as described below, the adhesion promoter is preferably contained in the first component from the viewpoint of storage stability.

[0058] As the adhesion promoter, an aminosilane coupling agent is preferred. Specific examples of the aminosilane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N,N'-bis-[3-(trimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(triethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(methyldimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(trimethoxysilyl)propyl]hexamethylenediamine, and N,N'-bis-[3-(triethoxysilyl)propyl]hexamethylenediamine. Of these, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is preferred.

[0059] The content of the adhesion promoter in the thermally conductive composition is preferably 1 to 10 parts by mass, and more preferably 1 to 8 parts by mass, per 100 parts by mass of the organic polymer containing a hydrolyzable silyl group. When the content of the adhesion promoter is equal to or greater than these lower limits, the adhesive strength of the cured product formed is likely to be improved, while when the content of the adhesion promoter is equal to or less than these upper limits, the cured product formed can be prevented from becoming brittle, thereby suppressing a decrease in adhesive strength.

[0060] <Dehydrating Agent> The thermally conductive composition of the present invention may contain a dehydrating agent. When the thermally conductive composition of the present invention is a two-component composition as described below, the dehydrating agent may be contained in the first part. The inclusion of a dehydrating agent can prevent the first part from curing due to moisture contained in the air or the like during storage. Examples of dehydrating agents include silane compounds such as vinyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane, and ester compounds such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, and ethyl orthoacetate. These dehydrating agents may be used alone or in combination of two or more. Among these, vinyltrimethoxysilane is preferred.

[0061] The content of the dehydrating agent is preferably 0.01 to 3 mass %, more preferably 0.05 to 2 mass %, and even more preferably 0.1 to 1 mass %, based on the total amount of the thermally conductive composition (i.e., based on the total amount of the thermally conductive composition obtained by mixing the first and second parts). When the content of the dehydrating agent is equal to or greater than these lower limits, curing of the first part during storage can be easily suppressed, and when the content of the dehydrating agent is equal to or less than these upper limits, a decrease in curability due to the dehydrating agent can be made less likely to occur.

[0062] <Two-Component Curing Thermally Conductive Composition> The thermally conductive composition of the present invention may be used as a one-component composition or as a two-component composition consisting of a first component and a second component. The two-component composition can improve storage stability. When used as a two-component composition, the thermally conductive composition of the present invention can be used, for example, as the second component as follows. That is, the present invention also provides a two-component curing thermally conductive composition comprising a first component containing a plasticizer, a thermally conductive filler, and a silanol catalyst and filled in a first container, and a second component containing an organic polymer having a hydrolyzable silyl group, a plasticizer, a thermally conductive filler, and water and filled in a second container. When in use, the thermally conductive composition obtained by mixing the first component and the second component is cured to form a thermally conductive member consisting of a cured product of the two-component curing thermally conductive composition.

[0063] The first agent may contain the organic polymer having a hydrolyzable silyl group described above, but preferably does not. By not including an organic polymer having a hydrolyzable silyl group in the first agent, thickening of the first agent during storage is suppressed, improving storage stability. The first agent preferably further contains the adhesion promoter and dehydrating agent described above in addition to the plasticizer, thermally conductive filler, and silanol catalyst. The second agent preferably further contains the compatibilizer described above in addition to the organic polymer having a hydrolyzable silyl group, plasticizer, thermally conductive filler, and water. The content of each component in the first agent and the second agent may be adjusted appropriately so that the amount of each component in the thermally conductive composition obtained by mixing the first agent and the second agent falls within the above-described range.

[0064] The volume ratio of the first agent to the second agent (second agent / first agent) is preferably 1 or a value close to 1, specifically preferably 0.9 to 1.1, and more preferably 0.95 to 1.05. In this way, by setting the volume ratio of the first agent to the second agent to a value close to 1, it becomes easy to prepare a mixture of the first agent and the second agent.

[0065] In the present invention, the first agent and the second agent may contain other additives such as a thixotropic agent, an antioxidant, an ultraviolet absorber, a dispersant, a pigment, a dye, an anti-settling agent, an ion trapping agent, and a solvent, as necessary.

[0066] (Storage Form) The first agent and the second agent are filled in separate containers, specifically, the first agent is filled in the first container and the second agent is filled in the second container. The first container and the second container may be separate or integrated. By integrating the first container and the second container, it becomes easier to supply them to the consumer as a container set. Note that in this specification, the first container filled with the first agent and the second container filled with the second agent may be collectively referred to as a container set.

[0067] 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 syringe 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.

[0068] 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.

[0069] The first and second agents may be mixed using a mixer such as a static mixer. As shown in FIG. 1 , the 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 (composition) 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 from the openings.

[0070] 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.

[0071] <Thermal Conductive Member> When the thermally conductive composition of the present invention is a one-component type, the thermally conductive composition can be cured to form a cured product, thereby forming a thermally conductive member. In the case of a two-component curing thermally conductive composition, the first and second components are mixed and cured to form a cured product, thereby forming a thermally conductive member. The thermally conductive member may be disposed between two components, such as a heat generating element and a heat dissipating element. Examples of the heat generating element include electronic components that generate heat, such as a battery. Examples of the heat dissipating element include a housing and cooling components, such as a heat sink or a cooling plate.

[0072] [Applications] The thermally conductive composition, two-component curing thermally conductive composition, and thermally conductive member of the present invention can be used in a variety of applications, for example, as a heat dissipation material for battery assemblies such as lithium-ion battery (LiB) assemblies, and further, can be used in various electronic device applications such as 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, in a preferred embodiment of the present invention, a battery assembly including the above-described thermally conductive member is provided. Note that battery assemblies such as LiB assemblies can be preferably used in automobiles such as electric vehicles.

[0073] In battery assembly applications, the thermally conductive composition, two-component curing thermally conductive composition, and thermally conductive member of the present invention are preferably used as a gap filler in a battery assembly. In one aspect, the thermally conductive composition, two-component curing thermally conductive composition, and thermally conductive member of the present invention are preferably used in a battery module, and more preferably as a gap filler in a battery module. Hereinafter, an example in which the thermally conductive member of the present invention is applied to a battery module will be described.

[0074] In one embodiment, 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 a separation between the battery cells. 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.

[0075] 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, multiple battery cells 11 are arranged inside the battery module 10. Each battery cell 11 is laminated and encapsulated 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, such a battery cell 11 may have a positive electrode 11a and a negative electrode 11b exposed to the outside, and a central portion 11c of the flat surface may be thicker than the crimped end portion 11d. It is also preferable that the surface of each battery cell 11 be coated with a resin material. Coating the surface of each battery cell 11 with a resin material makes it easier to ensure insulation. The resin material is not particularly limited, but examples include polyester resins such as PET (polyethylene terephthalate), polyimide resins, olefin resins such as polypropylene resins, and polycarbonate resins. Among these, PET is more preferable.

[0076] 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.

[0077] 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.

[0078] The gap material 13 can be formed in the battery module 10 by applying a mixture (composition) of a thermally conductive composition or a first and second component of a two-component curing thermally conductive composition using a general dispenser, followed by curing. It is preferable to use a two-component curing thermally conductive composition when forming the gap material 13. Two-component compositions are easy to store, and if mixed immediately before use, they are less likely to harden during application with a dispenser, allowing them to harden quickly after application. Dispenser application is also preferable because it allows the composition to be filled relatively deep within the housing 12 of the battery module 10.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] A schematic diagram of a battery assembly having a cell-to-pack structure is shown in Figure 5. A battery assembly 20 having a cell-to-pack structure includes a plurality of battery cells 21 and a battery pack housing. The plurality of battery cells 21 are bonded to a base member 25 constituting the battery pack housing via a gap material 23 made of a thermally conductive material. The base member 25 may constitute a cooling plate or the like. The base member 25 made of a cooling plate or the like may have an uneven surface, and the battery cells 21 may be bonded to the uneven surface of the base member 25 via the gap material 23. The gap material 23 in the battery assembly 20 may be formed in the same manner as the gap material 13 in the battery module described above, for example, by using a general dispenser.

[0083] In the above description, an example has been described in which the surfaces of the battery cells 11, 21 are coated with a resin material, but components other than the battery cells, such as base members such as a cooling plate, a battery module, a module housing, and a housing for a battery pack, may also be coated with or made of a resin material. Even in this case, the components can be appropriately bonded to each other by using the thermally conductive member of the present invention as a gap material disposed between the components.

[0084] 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.

[0085] In this example, the evaluation was carried out by the following method.

[0086] [Polar Term δP of Hansen Solubility Parameters of Non-reactive Components] The polar term δP of the Hansen Solubility Parameters of non-reactive components was calculated using a prediction method employing a neural network method called Y-MB using computer software Hansen Solubility Parameters in Practice (HSPiP 5th Edition (ver. 5.0.09)). Specifically, the Y-MB tool was used to automatically segment molecules from the structure of the substance, and the polar term δP of the Hansen Solubility Parameters of non-reactive components was calculated. Based on the polar term δP of the Hansen Solubility Parameters of non-reactive components calculated as described above, the sum of X represented by the following formula (1) was calculated. X = polar term δP of the Hansen Solubility Parameters of non-reactive components × volume of non-reactive components contained in the thermally conductive composition / volume of liquid contained in the thermally conductive composition Formula (1)

[0087] <Dielectric Constant Measurement> Using a rheometer manufactured by Anton Paar, the first and second parts of each example and comparative example were mixed at a volume ratio of 1:1, and the mixture was placed on a sample stage. It was then compressed to a thickness of 1 mm using parallel plates with a diameter of 30 mm, and cured at 60°C for 18 hours. After curing, the dielectric constant was measured at 18°C. In detail, the measurement terminals of an LCR meter (IM-3536) manufactured by HIOKI Corporation were connected to the parallel plates and sample stage of the rheometer, respectively, and the dielectric constant was measured at a frequency of 50 Hz.

[0088] [Thermal Conductivity] The thermal conductivity of each of the thermally conductive compositions of the Examples and Comparative Examples was measured using a cured product obtained by curing the composition for two weeks in an environment of 25°C and 50% RH. Thermal conductivity was determined by measuring thermal resistance using a measuring device conforming to ASTM D5470-06. Specifically, cured products of 1.0 mm, 1.5 mm, and 2.0 mm in thickness were prepared, and the thermal resistance and thickness were measured when compressed at a pressure of 30 psi. For these three thermal resistance values, a graph was created with thickness on the horizontal axis and thermal resistance on the vertical axis, and an approximate line between three points was obtained using the least squares method. The slope of the approximate line was then the thermal conductivity. Thermal resistance measurements were performed at 80°C using an LW-9389 thermometer manufactured by Long Win Science and Technology Corporation.

[0089] In the examples and comparative examples, the following components were used.

[0090] <Organic polymers having hydrolyzable silyl groups> Kaneka Corporation's "MS polymer SAT350", number average molecular weight 6,800, linear type, terminal silylation rate 91%, organic polymer having dimethoxymethylsilyl groups at both ends of polypropylene oxide Kaneka Corporation's "MS polymer S327", number average molecular weight 25,000, linear type, terminal silylation rate 70%, organic polymer having dimethoxymethylsilyl groups at both ends of polypropylene oxide AGC Corporation's "S4530", number average molecular weight 25,000, linear type, terminal silylation rate 86%, organic polymer having dimethoxymethylsilyl groups at both ends of polypropylene oxide

[0091] <Aluminum hydroxide> Aluminum hydroxide 1: average particle size 1 μm, specific surface area 3.8 m ２ / g, specific gravity 2.4g / cm ３ Aluminum hydroxide 2: average particle size 10 μm, specific surface area 2.01 m ２ / g, specific gravity 2.4g / cm ３ Aluminum hydroxide 3: average particle size 105 μm, specific surface area 0.01 m ２ / g, specific gravity 2.4g / cm ３

[0092] <Aluminum oxide> Aluminum oxide 1: average particle size 4.7 μm, specific surface area 0.27 m ２ / g, specific gravity 3.94g / cm ３ Aluminum oxide 2: average particle size 12.5 μm, specific surface area 0.16 m ２ / g, specific gravity 3.94g / cm ３ Aluminum oxide 3: average particle size 42.8 μm, specific surface area 0.14 m ２ / g, specific gravity 3.94g / cm ３ Aluminum oxide 4: average particle size 71.6 μm, specific surface area 0.14 m ２ / g, specific gravity 3.94g / cm ３

[0093] <Non-reactive components> (Plasticizer) 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH) δP = 1.9 Triethylene glycol di-2-ethylhexanoate (3GO) δP = 3.3 Diisononyl adipate (DINA) δP = 2.3 Polytetramethylene glycol (PTMG) δP = 8.4 (Compatibilizer) Butyl carbitol δP = 6.2

[0094] <Additives> Silanol condensation catalyst: dibutyltin dilaurate (organotin compound) Dehydrating agent: vinyltrimethoxysilane Adhesion promoter: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane Ion scavenger: IXE100 (manufactured by Toagosei Co., Ltd.)

[0095] [Examples 1 to 4, 7] A first part containing a plasticizer, a thermally conductive filler, an adhesion promoter, a dehydrating agent, and a silanol catalyst was mixed with a second part containing an organic polymer having a hydrolyzable silyl group, a plasticizer, a thermally conductive filler, and water to prepare thermally conductive compositions having the formulations shown in Table 1. The dielectric constant and thermal conductivity of the obtained thermally conductive compositions were evaluated.

[0096] [Examples 5 to 6, Comparative Examples 2 to 5] Except for further blending a compatibilizer into the second part, thermally conductive compositions having the formulations shown in Table 1 were prepared in the same manner as in Example 1. The dielectric constant and thermal conductivity of the obtained thermally conductive compositions were evaluated.

[0097] [Example 8] A thermally conductive composition having the formulation shown in Table 1 was prepared in the same manner as in Example 1, except that an ion-trapping material was further added to the second part. The dielectric constant and thermal conductivity of the obtained thermally conductive composition were evaluated.

[0098] [Comparative Example 1] A thermally conductive composition having the formulation shown in Table 1 was prepared in the same manner as in Example 1, except that a compatibilizer and an ion-capturing material were further blended into the second part. The dielectric constant and thermal conductivity of the obtained thermally conductive composition were evaluated.

[0099]

[0100] The thermally conductive compositions of Examples 1 to 8 are thermally conductive compositions containing a hydrolyzable silyl group-containing organic polymer, a non-reactive component, and a predetermined amount or more of aluminum oxide, and are thermally conductive compositions of the present invention in which the sum of X expressed by formula (1), calculated based on the polar term δP of the Hansen solubility parameter of the non-reactive component, is 1.5 or less. The thermally conductive compositions of the present invention in each of these Examples exhibited high thermal conductivity and low dielectric constant due to the inclusion of a predetermined amount or more of aluminum oxide. In contrast, the thermally conductive compositions of Comparative Examples 1 to 5 exhibited a higher dielectric constant than the Examples in which the sum of X expressed by formula (1), calculated based on the polar term δP of the Hansen solubility parameter of the non-reactive component, exceeded 1.5.

[0101] 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 thermally conductive composition comprising an organic polymer having a hydrolyzable silyl group, a non-reactive component, and a thermally conductive filler, wherein the thermally conductive filler contains aluminum oxide, the content of the aluminum oxide is 10% by volume or more of the total volume of the thermally conductive composition, and the surface area of ​​the aluminum oxide per 1 g of the thermally conductive composition is 0.07 m ２ The thermally conductive composition is such that the sum of X's expressed by formula (1) calculated based on the polar term δP of the Hansen solubility parameter of the non-reactive component is 1.5 or less, X = polar term δP of the Hansen solubility parameter of the non-reactive component × volume of the non-reactive component contained in the thermally conductive composition / volume of the liquid content contained in the thermally conductive composition Formula (1) 2. The thermally conductive composition according to claim 1, wherein the organic polymer having a hydrolyzable silyl group has a main chain consisting of a polyether skeleton.

3. The thermally conductive composition according to claim 1 or 2, wherein the thermally conductive filler comprises aluminum hydroxide.

4. The thermally conductive composition of claim 1 or 2, wherein the non-reactive component comprises a plasticizer.

5. The thermally conductive composition according to claim 1 or 2, which is a two-component curing type consisting of a first part filled in a first container and a second part filled in a second container.

6. The thermally conductive composition according to claim 5, wherein the first part comprises a plasticizer, a thermally conductive filler, and a silanol catalyst.

7. The thermally conductive composition according to claim 6, wherein the first agent does not contain an organic polymer having a hydrolyzable silyl group.

8. The thermally conductive composition according to claim 5, wherein the second agent contains an organic polymer having a hydrolyzable silyl group, a plasticizer, a thermally conductive filler, and water.

9. The thermally conductive composition of claim 8, wherein the second part comprises a compatibilizer.

10. A thermally conductive member comprising a cured product of the thermally conductive composition according to claim 1.

11. A battery assembly comprising the thermally conductive member according to claim 10.

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