Curable composition and cured product

Abstract

The present invention provides a curable composition and a cured product thereof, the curable composition containing a thermally conductive filler, a monomer M1, a monomer M2, a polymerization initiator, and a dispersant, wherein the monomer M1 includes a monomer represented by formula 1 or includes a monomer consisting of a (meth)acryloyl group and a residue having a heterocyclic structure, and the monomer M2 includes a monomer consisting of a (meth)acryloyl group and a residue that does not have a heterocyclic structure (provided that the monomer M2 does not include a monomer represented by formula 1).

Description

Curable composition and cured product

[0001] This disclosure relates to curable compositions and cured products.

[0002] In recent years, the performance of electronic devices such as personal computers, mobile phones, Personal Digital Assistants (PDAs), and lighting and display devices such as light-emitting diodes (LEDs) and Electronic Luminescents (ELs) has improved remarkably, largely due to significant improvements in the performance of computing elements and light-emitting elements. However, this improvement in performance has also led to a significant increase in heat generation, making heat dissipation in electronic devices, lighting, and display devices a critical issue. As a thermal countermeasure, a TIM (Thermal Interface Material; thermally conductive material) is used between the heat-generating element and the heat-sink to transfer the heat generated by the computing element or light-emitting element to the heat sink without loss, and to dissipate the heat through the heat sink. Commonly used TIMs include heat dissipation sheets, thermally conductive grease, and gap fillers. Gap fillers, which are initially paste-like and harden into a solid after application, are attracting particular attention.

[0003] As a composition to be applied as TIM, for example, Patent Document 1 discloses a thermally conductive silicone rubber composition containing (A) an organopolysiloxane having a viscosity of 50 to 100,000 mPa·s at 25°C and containing an average of two or more silicon atom-bonded alkenyl groups per molecule, (B) an organopolysiloxane having a viscosity of 1 to 100,000 mPa·s at 25°C and containing an average of two or more silicon atom-bonded hydrogen atoms per molecule, (C) a thermally conductive filler, (D) a platinum catalyst, and (E) a specific amount of an organopolysiloxane having a predetermined structure and a molecular weight of 10,000 or more.

[0004] Furthermore, Patent Document 2 discloses a curable composition comprising a compound (A) having one (meth)acrylate group in one molecule, a compound (B) having two or more (meth)acrylate groups in one molecule, a polymerization initiator (C), a dispersant (D), and a thermally conductive filler (E) containing zinc oxide or magnesium oxide.

[0005] Patent Document 1: Japanese Unexamined Patent Publication No. 2005-325211 Patent Document 2: International Publication No. 2020 / 149193

[0006] TIMs (Thermal Insulation Materials) are sometimes required to possess not only thermal conductivity but also adhesive properties, that is, to be heat-dissipating adhesives. Heat-dissipating adhesives are expected to be subjected to environments with more drastic temperature changes than conventional adhesives. On the other hand, curable resins such as acrylic resins and epoxy resins, which are commonly used as adhesive materials, form a very hard skeleton after the curing reaction, resulting in a cured product with low flexibility. As a result, the cured product cannot follow the expansion and contraction caused by heat and is vulnerable to thermal changes. From this perspective, there is currently a demand for curable compositions that achieve both adhesion and flexibility.

[0007] One embodiment of the present disclosure, in view of the above circumstances, aims to provide a curable composition that yields a cured product with excellent adhesion and flexibility, and a cured product with excellent adhesion and flexibility.

[0008] The present disclosure includes the following aspects: <1> A curable composition comprising a thermally conductive filler, monomer M1, monomer M2, polymerization initiator, and dispersant, wherein monomer M1 comprises a monomer represented by the following formula 1, and monomer M2 comprises a monomer consisting of a (meth)acryloyl group and a residue that does not have a heterocyclic structure (however, monomer M2 does not contain the monomer represented by the following formula 1). In formula 1, R １ ~R １０ Each of these independently represents a hydrogen atom or an organic group.

[0009] <2> A curable composition comprising a thermally conductive filler, monomer M1, monomer M2, polymerization initiator, and dispersant, wherein monomer M1 comprises a monomer consisting of a (meth)acryloyl group and a residue having a heterocyclic structure, and monomer M2 comprises a monomer consisting of a (meth)acryloyl group and a residue not having a heterocyclic structure (however, monomer M2 does not contain the monomer represented by the following formula 1). In formula 1, R １ ~R １０Each of these independently represents a hydrogen atom or an organic group.

[0010] <3> In formula 1, R １ R represents the group shown in the following formula 2, ２ ~R １０ The curable composition described in <1>, wherein each of these represents a hydrogen atom. In equation 2, * indicates the bonding position.

[0011] <4> The curable composition according to any one of <1> to <3>, wherein the content of monomer M1 is 5% by mass or more and 35% by mass or less on a mass basis, relative to the total content of monomer M1 and monomer M2. <5> The curable composition according to any one of <1> to <4>, wherein the content of monomer M1 is 10% by mass or more and 30% by mass or less on a mass basis, relative to the total content of monomer M1 and monomer M2. <6> The curable composition according to any one of <1> to <5>, wherein the residue in monomer M2 that does not have a heterocyclic structure is an organic group with a total of 12 or more carbon atoms. <7> The curable composition according to any one of <1> to <6>, wherein the thermally conductive filler contains zinc oxide. <8> A cured product of the curable composition according to any one of <1> to <7>.

[0012] According to one embodiment of the present disclosure, a curable composition can be provided that yields a cured product with excellent adhesion and flexibility, and a cured product with excellent adhesion and flexibility can be provided.

[0013] The curable compositions and cured products relating to this disclosure will be described in detail below.

[0014] In this disclosure, the "~" symbol indicating a numerical range represents a range that includes the numerical values ​​specified as its upper and lower limits, respectively. Furthermore, if only the upper limit of a numerical range represented by "~" has a unit specified, it means that the lower limit also has the same unit. In this disclosure, if there are multiple substances corresponding to each component in a composition, the content or amount of each component in the composition means the total content or amount of those multiple substances present in the composition, unless otherwise specified. In numerical ranges described in stages in this disclosure, the upper or lower limit specified in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In numerical ranges described in this disclosure, the upper or lower limit specified in one numerical range may be replaced with the values ​​shown in the examples.

[0015] In this disclosure, "(meth)acrylic" is a term used to encompass both acrylic and methacrylic, and "(meth)acryloyl" is a term used to encompass both acryloyl and methacryloyl. In this disclosure, each component in a composition means the total amount of the applicable substance present in the composition if there are multiple instances of that component in the composition, unless otherwise specified. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0016] In this disclosure, "JIS" is used as an abbreviation for Japanese Industrial Standards. In this disclosure, "ASTM" means international standards developed by ASTM International. In this disclosure, ordinal numbers (e.g., "1st" and "2nd") are terms used to distinguish multiple components and do not limit the number of components or the order of their importance.

[0017] In this disclosure, “monomer” means a polymerizable compound having a molecular weight of less than 1,000. In this disclosure, “polymer” means a compound having a weight-average molecular weight (Mw) of 1,000 or more. In this disclosure, the concept of “polymer” also includes so-called oligomers.

[0018] (Curable Composition) The curable composition according to the present disclosure includes a first aspect and a second aspect. In the following description, matters not explicitly stated as being the first aspect or the second aspect shall be common to both the first aspect and the second aspect.

[0019] A first aspect of the curable composition according to the present disclosure contains a thermally conductive filler, a monomer M1, a monomer M2, a polymerization initiator, and a dispersant, wherein the monomer M1 includes a monomer represented by Formula 1 below, and the monomer M2 includes a monomer consisting of a (meth)acryloyl group and a residue having no heterocyclic structure. (Provided that the monomer M2 does not include a monomer represented by Formula 1 below.)

[0020]

[0021] In Formula 1, R １ to R １０ each independently represent a hydrogen atom or an organic group.

[0022] A second aspect of the curable composition according to the present disclosure contains a thermally conductive filler, a monomer M1, a monomer M2, a polymerization initiator D, and a dispersant E, wherein the monomer M1 includes a monomer consisting of a (meth)acryloyl group and a residue having a heterocyclic structure, and the monomer M2 includes a monomer consisting of a (meth)acryloyl group and a residue having no heterocyclic structure (provided that the monomer M2 does not include a monomer represented by Formula 1 above).

[0023] The curable composition according to the present disclosure, having the above configuration, can provide a cured product excellent in adhesiveness and flexibility. Although the reason for this is not clear, it is presumed as follows; provided that the following presumption does not limit the interpretation of the curable composition according to the present disclosure, and is described as an example.

[0024] Both the monomer M1 and the monomer M2 contained as curing components in the curable composition according to the present disclosure are acrylic monomers, and a cured product excellent in adhesiveness can be obtained. Furthermore, in the curable composition of the first aspect, the monomer represented by Formula 1 contained as the monomer M1 undergoes cyclopolymerization, so the cured product of the curable composition contains a polymer having a heterocyclic structure. Also, in the curable composition of the second aspect, the monomer composed of a (meth)acryloyl group and a residue having no heterocyclic structure, which is contained as the monomer M1, has a residue having a heterocyclic structure, so the cured product of the curable composition contains a polymer having a heterocyclic structure. It is presumed that, because the cured product contains a polymer having a heterocyclic structure, the cured product obtained from the curable composition according to the present disclosure, combined with excellent adhesiveness, ensures appropriate flexibility.

[0025] Hereinafter, each component contained in the curable composition according to the present disclosure will be described.

[0026] <Thermally Conductive Filler> The curable composition according to the present disclosure contains a thermally conductive filler. The material of the thermally conductive filler is not particularly limited, and examples thereof include zinc oxide, magnesium oxide, aluminum oxide, boron nitride, aluminum nitride, carbon, and the like. From the viewpoints of insulation properties, high thermal conductivity, and track record of use as a thermally conductive filler, the thermally conductive filler preferably contains at least one selected from aluminum nitride, zinc oxide, magnesium oxide, and aluminum oxide, more preferably contains aluminum nitride or zinc oxide, and further preferably contains zinc oxide from the viewpoints of dispersibility and the viscosity of the curable composition.

[0027] The thermally conductive filler may be a surface-treated thermally conductive filler. The surface-treated thermally conductive filler can improve affinity with other contained components other than the thermally conductive filler, and contribute to lower viscosity and improved thermal conductivity.

[0028] The surface treatment for the thermally conductive filler is not particularly limited, and may be either physical treatment or chemical treatment. Any known treatment capable of treating the surface of particles constituting the thermally conductive filler can be applied. The surface treatment is preferably a treatment using a surface treatment agent.

[0029] Examples of the surface treatment agent include silane coupling agents, titanium coupling agents, carboxylic acid coupling agents, phosphoric acid coupling agents, fatty acids, high molecular weight compounds, surfactants, and oils and fats.

[0030] From the viewpoint of dispersibility, the thermally conductive filler is preferably surface-treated using a silane coupling agent as the surface treatment agent.

[0031] - Content - The content of the thermally conductive filler is preferably 87% by mass or more, more preferably 90% by mass to 98% by mass, and still more preferably 92% by mass to 96% by mass, relative to the total mass of the composition. Further, the content of the thermally conductive filler is preferably 40% by volume or more, more preferably 47% by volume to 80% by volume, and still more preferably 60% by volume to 80% by volume, relative to the total volume of the curable composition. When the content of the thermally conductive filler falls within the above range, high thermal conductivity can be obtained.

[0032] <Monomer M1> The curable composition according to the present disclosure contains monomer M1. Monomer M1 includes a monomer represented by the following Formula 1 (hereinafter also referred to as "monomer M1a"), and a monomer composed of a (meth)acryloyl group and a residue having a heterocyclic structure (hereinafter also referred to as "monomer M1b"). In the polymer derived from monomer M1, a polymer containing a heterocyclic structure in the molecule is formed from both monomer M1a and monomer M1b.

[0033] <<Monomer Represented by Formula 1>> The curable composition according to the first aspect contains, as monomer M1, a monomer represented by the following Formula 1 (monomer M1a). The curable composition according to the first aspect may contain only one type of monomer M1a, or may contain two or more types thereof.

[0034]

[0035] In formula 1, R １ ~R １０ Each of these independently represents a hydrogen atom or an organic group. In this disclosure, an organic group means a functional group containing one or more carbon atoms.

[0036] R １ ~R １０ Examples of organic groups represented by include alkyl groups, alkyl ester groups, alkyl hydroxy groups, alkyl carboxyl groups, alkyl carbonyl groups, alkyl amino groups, alkyl cyano groups, and alkyl sulfo groups.

[0037] Among these, the monomer M1a is R in formula 1. １ R represents the group represented by the following formula 2 (i.e., a methyl ester group), ２ ~R １０ It is more preferable that all of these compounds represent hydrogen atoms (i.e., methyl 2-allyloxymethylacrylate).

[0038]

[0039] In equation 2, * indicates the bonding position.

[0040] In the curable composition of the first embodiment, the content of monomer M1 is preferably 0.5% to 5% by mass, and more preferably 0.75% to 3% by mass, based on the total mass of the curable composition.

[0041] <<Monomer consisting of a (meth)acryloyl group and a residue having a heterocyclic structure>> The curable composition of the second embodiment contains a monomer (monomer M1b) as monomer M1, which consists of a (meth)acryloyl group and a residue having a heterocyclic structure. The curable composition of the second embodiment may contain only one type of monomer M1b, or it may contain two or more types.

[0042] Monomer M1b may be a monomer having one or more (meth)acryloyl groups in one molecule, and preferably a monomer having one (meth)acryloyl group in one molecule.

[0043] From the viewpoint of curability, the (meth)acryloyl group of monomer M1b is preferably an acryloyl group, and from the viewpoint of low skin irritation and flexibility, it is preferably a methacryloyl group.

[0044] In the heterocyclic residues of monomer M1b, examples of heterocyclic structures include tetrahydrofuran rings, azetidine rings, oxetane rings, thietan rings, diazetidine rings, dioxetane rings, dithietan rings, borolan rings, borol rings, pyrrolidine rings, pyrrole rings, furan rings, phosphorane rings, phosphole rings, tetrahydrotiphophene rings, imitazolidine rings, imidazole rings, oxazolidine rings, oxazole rings, thiazolidined rings, thiazole rings, dioxolane rings, diotilane rings, piperidine rings, pyridine rings, tetrahydropyran rings, pyran rings, phosphinan rings, phospholine rings, thian rings, thiopyran rings, piperazine rings, diazine rings, morpholine rings, oxazine rings, thiomorpholine rings, thiadin rings, dioxane rings, dioxin rings, dithiane rings, dithiine rings, etc., with tetrahydrofuran rings being preferred.

[0045] A preferred residue having a heterocyclic structure in monomer M1b is, for example, a tetrahydrofurfuryl group.

[0046] As for monomer M1b, for example, from the viewpoint of achieving both adhesion and flexibility, tetrahydrofurfuryl acrylate or tetrahydrofurfuryl methacrylate are preferred.

[0047] In the curable composition of the second embodiment, the content of monomer M1 is preferably 0.5% to 5% by mass, and more preferably 0.75% to 3% by mass, based on the total mass of the curable composition.

[0048] <Monomer M2> The curable composition according to this disclosure contains monomer M2. Monomer M2 is a monomer consisting of a (meth)acryloyl group and a residue that does not have a heterocyclic structure (however, monomer M2 does not include the monomer represented by formula 1 above).

[0049] Monomer M2 may be a monomer having one (meth)acryloyl group in one molecule, or a monomer having two or more (meth)acryloyl groups in one molecule.

[0050] In monomer M2, residues that do not have a heterocyclic structure include hydroxyl groups and organic groups that do not have a heterocyclic structure.

[0051] In monomer M2, as a residue that does not have a heterocyclic structure, an organic group with a total number of carbon atoms of 12 or more (preferably 12 to 40, more preferably 12 to 32) is preferred from the viewpoint of imparting flexibility to the cured product.

[0052] Examples of monomer M2 include linear, branched, or cyclic alkyl (meth)acrylates, acrylic acid, and the like.

[0053] In one embodiment, monomer M2 may include monomers having one or more (meth)acrylate groups in a single molecule, from the viewpoint of achieving both heat resistance and flexibility. It is preferable that monomers having linear, branched, or cyclic alkyl (meth)acrylates are included, and it is even more preferable that monomers represented by the following formula 3 are included.

[0054]

[0055] In formula 3, R １ R represents a linear, branched, or cyclic alkyl group having 1 to 50 carbon atoms. ２ represents a hydrogen atom or a methyl group.

[0056] In formula 3, R １ The alkyl group in the alkyl group may be linear, branched, or cyclic. The alkyl group may also have substituents. Examples of substituents include carboxyl groups, hydroxyl groups, amino groups, and aryl groups, but a carboxyl group or a hydroxyl group is preferred, and a hydroxyl group is more preferred.

[0057] From the viewpoint of achieving both heat resistance and flexibility, R １The number of carbon atoms in the alkyl group is preferably 2 to 30, more preferably 5 to 25, even more preferably 10 to 25, and particularly preferably 12 to 18. Here, the number of carbon atoms refers to the total number of carbon atoms, including the number of carbon atoms of the substituents if the alkyl group has substituents containing carbon atoms.

[0058] From the viewpoint of achieving both heat resistance and flexibility, in formula (3), R １ It is preferably a linear, branched, or cyclic alkyl group having a total of 2 to 30 carbon atoms, and may have substituents; more preferably, it is a linear, branched, or cyclic alkyl group having a total of 2 to 25 carbon atoms, and may have a hydroxyl group.

[0059] Examples of monomer M2 include lauryl (meth)acrylate, isostearyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-decyltetradecyl (meth)acrylate, decyltetradecanol monomethacrylate, 2-ethylhexyl methacrylate, 2-hydroxypropyl methacrylate, 2-methacryloyloxyethyl succinate, and isobornyl acrylate.

[0060] In formula 3, R ２ This is a hydrogen atom or a methyl group, and a methyl group is preferred.

[0061] In one embodiment, monomer M2 may include monomers having two or more (meth)acrylate groups in one molecule. Examples of monomers having two or more (meth)acrylate groups in one molecule include hexanediol di(meth)acrylate, butanediol di(meth)acrylate (1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate), ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, and the like.

[0062] In one embodiment, monomer M2 may include a monomer having two or more (meth)acrylate groups in one molecule, from the viewpoint of achieving both heat resistance and flexibility. The monomer having two or more (meth)acrylate groups in one molecule is preferably a compound having two and / or three (meth)acrylate groups in one molecule, more preferably a compound having two (meth)acrylate groups in one molecule, and even more preferably a compound represented by the following formula 4.

[0063]

[0064] In formula 4, R Ｂ１ R represents an alkylene group with 1 to 5 carbon atoms. Ｂ２ and R Ｂ３ Each of these independently represents either a hydrogen atom or a methyl group, and n represents an integer of 4 or greater. Ｂ１ The alkylene group having 1 to 5 carbon atoms, represented by , may be linear or branched. From the viewpoint of flexibility, R Ｂ１The alkylene group represented by is preferably a branched alkylene group having 2 to 5 carbon atoms, more preferably a linear or branched alkylene group having 2 to 4 carbon atoms, and even more preferably a branched alkylene group having 3 or 4 carbon atoms. Ｂ２ and R Ｂ３ Each of these is preferably a methyl group. n is preferably 4 to 25, more preferably 4 to 10, and even more preferably 3 to 8.

[0065] From the viewpoint of flexibility and shape stability, in formula 4, R Ｂ１ R is a branched alkylene group having 2 to 5 carbon atoms (more preferably a linear or branched alkylene group having 2 to 4 carbon atoms, and even more preferably a branched alkylene group having 3 or 4 carbon atoms), Ｂ２ and R Ｂ３ The group is a methyl group, and n is preferably 4 to 25 (more preferably 4 to 10, and even more preferably 3 to 8).

[0066] In one embodiment, monomer M2 preferably comprises at least one monomer selected from monomers having one (meth)acrylate group in one molecule, and at least one monomer selected from monomers having two or more (meth)acrylate groups in one molecule.

[0067] In the curable composition according to this disclosure, the monomer M2 content is preferably 0.5% to 20% by mass, and more preferably 1% to 15% by mass, based on the total mass of the curable composition.

[0068] In the curable composition according to this disclosure, from the viewpoint of achieving both adhesion and flexibility, the content of monomer M1 is preferably 5% by mass or more and 35% by mass or less, and more preferably 10% by mass or more and 30% by mass or less, based on the total content of monomer M1 and monomer M2.

[0069] <Polymerization Initiator> The curable composition according to this disclosure contains a polymerization initiator. The polymerization initiator is a compound that generates polymerization initiating species such as radicals and cations by light, heat, or both energy, and known thermal polymerization initiators, known photopolymerization initiators, etc., can be appropriately selected and used. From the viewpoint of reactivity with monomers M1 and M2, radical polymerization initiators are preferred as polymerization initiators, peroxides that generate free radicals by heat are more preferred, and organic peroxides that generate free radicals by heat are even more preferred.

[0070] Examples of organic peroxides include isobutyl peroxide, α,α'bis(neodecanoylperoxy)diisopropylbenzene, cumyl peroxyneodecanoate, di-n-propyl peroxydicarbonate, di-s-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl)peroxydicarbonate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, di-2-ethoxyethyl peroxydicarbonate, and di(ethylhexyl)peroxy Sidic carbonate, t-hexyl peroxyneodecanoate, dimethoxybutyl peroxydicarbonate, di(3-methyl-3-methoxybutyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, succinic peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoyl)hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, t-butylperoxy-2-ethylhexanoate, m-toluylbenzoyl peroxide, benzoyl peroxide, t-butylperoxyisobutyrate, 1,1-bis(t-butylperoxy)2-methylcyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1 -Bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexanone, 2,2-bis(4,4-dibutylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di(m-toluylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl carbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxyacetate, 2,2-bis(t-butylperoxy)butane, t-butylperoxybenzoate, n-butyl-4,4-bis(t-butylperoxy)valerate, di-t-butylperoxyisophthalate, α,α'bis(t-butylperoxy)diisopropylbenzene, dicumylperoxy Examples of peroxides include benzoyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexine, diisopropylbenzene hydroperoxide, t-butyltrimethylsilyl peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, and lauroyl peroxide. Among these, from the viewpoint of reactivity, the organic peroxide is preferably at least one compound selected from the group consisting of benzoyl peroxide, t-butylperoxy-2-ethylhexyl monocarbonate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, and cumene hydroperoxide.

[0071] The content of the polymerization initiator is preferably 0.5 parts by mass or more and 10 parts by mass or less, and more preferably 0.5 parts by mass or more and 4 parts by mass or less, based on 100 parts by mass of the total content of monomers contained in the curable composition.

[0072] <Dispersant> The curable composition according to this disclosure contains a dispersant. There are no particular limitations on the dispersant, and examples include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, polymeric surfactants, alcohols, compounds having a carboxyl group such as fatty acids, metal soaps, fatty acid oligomer compounds, fluorinated surfactants, boron-based surfactants, and the like.

[0073] Among the above dispersants, the dispersant is preferably at least one compound selected from the group consisting of nonionic surfactants, compounds having a carboxyl group, and metal soaps, and more preferably a compound having a carboxyl group.

[0074] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, polyglycerin fatty acid esters, polyglycerin fatty acid ethers, polyglycerin monoalkyl ethers, sucrose fatty acid esters, polyoxyethylene alkylamines, polyethylene glycol polypropylene glycol block copolymers, acetylene glycol, and polyoxyethylene adducts of acetylene glycol.

[0075] The compounds having a carboxyl group are not particularly limited and may be fatty acids having one carboxyl group and one hydrocarbon group in one molecule, or compounds having two or more carboxyl groups in one molecule.

[0076] Compounds containing a carboxyl group include aromatic carboxylic acids and fatty acids having an aliphatic hydrocarbon group with 12 to 22 carbon atoms. Other compounds containing a carboxyl group include polycarboxylic acids (polycarboxylic acids) having two or more carboxyl groups in one molecule, such as oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, and adipic acid; polycarboxylic acid salts such as alkylamine salts, alkylammonium salts, polycarboxylic acid polyaminoamides, sodium polycarboxylic acid salts, ammonium polycarboxylic acid salts, and amino alcohol polycarboxylic acid salts; and polycarboxylic acid copolymers.

[0077] Examples of metal soaps include metal salts of higher fatty acids such as calcium stearate, potassium oleate, and calcium oleate.

[0078] Among the above dispersants, the dispersant is preferably a compound having a carboxyl group, and more preferably a fatty acid having an aliphatic hydrocarbon group with 12 to 22 carbon atoms. Examples of fatty acids having an aliphatic hydrocarbon group with 12 to 22 carbon atoms include stearic acid, oleic acid, palmitic acid, myristic acid, and lauric acid, with oleic acid being preferred.

[0079] The dispersant content is preferably 0.1 parts by mass or more and 1.0 part by mass or less, more preferably 0.1 parts by mass or more and 0.8 parts by mass or less, and particularly preferably 0.1 parts by mass or more and 0.5 parts by mass or less, per 100 parts by mass of thermally conductive filler.

[0080] <Plasticizer> The curable composition according to this disclosure may contain a plasticizer. The plasticizer is not particularly limited as long as it is a compound that does not form a crosslinked structure with monomers, etc. Examples include polymers used as plasticizers, fatty acid ester compounds having unsaturated hydrocarbon groups, aromatic carboxylic acid ester compounds, as well as oils containing fatty acids and aromatic carboxylic acids having unsaturated hydrocarbon groups.

[0081] Examples of polymers used as plasticizers include acrylic polymers, polyester polymers, polyurethane polymers, and silicone polymers, but acrylic polymers are preferred from the viewpoint of heat resistance and flexibility of the resulting cured product.

[0082] As an acrylic polymer, it is preferable to include structural units formed from acrylic acid esters from the viewpoint of heat resistance. As the (meth)acrylic ester, alkyl (meth)acrylate is preferred. Examples of meth)acrylic esters include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate. Furthermore, the alkyl acrylate may be an unfunctional alkyl acrylate, or it may have a functional group such as a carboxyl group or a hydroxyl group. The functional group of the alkyl acrylate is preferably a hydroxyl group.

[0083] Acrylic polymers are given by the following formula (P ＡＣ The polymer may have a structure represented by ).

[0084]

[0085] Formula (P ＡＣ ) Medium, R ｐ represents a hydrogen atom or an alkyl group. Formula (P ＡＣ In the alkyl group, substituents may be present. Examples of substituents include carboxyl groups, hydroxyl groups, and amino groups. Carboxyl groups or hydroxyl groups are preferred substituents, and hydroxyl groups are more preferred. Saturated alkyl groups are preferred alkyl groups, such as methyl groups, ethyl groups, propyl groups, butyl groups, and hexyl groups. Among these, alkyl groups having 1 to 4 carbon atoms are more preferred.

[0086] When the plasticizer contained in the curable composition according to this disclosure is a polymer, from the viewpoint of the heat resistance and flexibility of the resulting cured product, it is preferable that the polymer has a glass transition temperature of -20°C or lower, and more preferably that it is an acrylic polymer with a glass transition temperature of -20°C or lower.

[0087] When the plasticizer contained in the curable composition according to this disclosure is a polymer, from the viewpoint of the heat resistance and flexibility of the resulting cured product, it is preferable that the polymer has a glass transition temperature of -90°C or higher and -20°C or lower, and more preferably that it is an acrylic polymer with a glass transition temperature of -90°C or higher and -20°C or lower.

[0088] The glass transition temperature (Tg) of a polymer can be determined by examining the inflection point of the DSC curve, which is measured using a differential thermal analyzer (DSC).

[0089] When the plasticizer contained in the curable composition according to this disclosure is a compound other than a polymer, it is preferable that the compound has a softening temperature of -20°C or lower, and more preferably a compound with a softening temperature of -25°C or lower, from the viewpoint of the heat resistance and flexibility of the resulting cured product. The softening temperature of the compound other than a polymer can be determined by examining the inflection point of the DSC curve measured using a differential thermal analyzer (DSC).

[0090] Examples of fatty acid ester compounds having unsaturated hydrocarbon groups include ester compounds of palmitoleic acid, oleic acid, linoleic acid, and linolenic acid. Examples of aromatic carboxylic acid ester compounds include ester compounds of phthalic acid, terephthalic acid, benzoic acid, and trimellitic acid.

[0091] When the curable composition according to this disclosure contains a plasticizer F, from the viewpoint of high-temperature stability, the plasticizer F preferably contains an aromatic carboxylic acid ester compound, and more preferably contains a trimellitic acid ester.

[0092] In a curable composition, the plasticizer may be included alone or in combination of two or more types.

[0093] The plasticizer content is preferably 0.1 parts by mass or more and 3 parts by mass or less, more preferably 0.1 parts by mass or more and 2.5 parts by mass or less, and particularly preferably 0.5 parts by mass or more and 2.0 parts by mass or less, per 100 parts by mass of thermal conductive filler.

[0094] <Other Additives> The curable composition according to this disclosure may optionally contain components other than the thermally conductive filler, monomer M1, monomer M2, polymerization initiator, dispersant, and plasticizer described above (hereinafter also referred to as "other additives"). Other additives may include reducing agents, antioxidants, corrosion inhibitors, rust inhibitors, rheology control agents (viscosity modifiers), etc. Other additives may be included individually or in combination of two or more.

[0095] <Reducing Agent> The curable composition according to this disclosure may contain a reducing agent as needed. When the curable composition according to this disclosure is applied to a two-component curable composition described later, it is preferable to include a reducing agent in one of the compositions. Adding a reducing agent makes it easier to decompose the polymerization initiator D (e.g., a peroxide), and the polymerization reaction proceeds more easily even under low temperature conditions.

[0096] As a reducing agent, there are no particular restrictions as long as it can promote the decomposition of the polymerization initiator, and known reducing agents used in combination with polymerization initiators can be used, but from the viewpoint of promoting the decomposition of the polymerization initiator, a metal compound-based reducing agent is preferred.

[0097] Examples of metal compound reducing agents include stannous oxide, dioctyl tin dilaurate, dibutyl tin dilaurate, dibutyl tin diacetate, zinc naphthenate, antimony trichloride, potassium oleate, sodium O-phenylphenate, bismuth nitrate, ferric chloride, tetra-n-butyltin, tetra(2-ethylhexyl) titanate, cobalt 2-ethylhexoate, and iron 2-ethylhexoate.

[0098] When the curable composition according to this disclosure contains a reducing agent, from the viewpoint of curing speed, the content of the reducing agent is preferably 0.5 parts by mass or more and 10 parts by mass or less, and more preferably 2 parts by mass or more and 9 parts by mass or less, based on 100 parts by mass of the total content of monomers contained in the curable composition. The reducing agent may be used alone or two or more types may be used in combination.

[0099] <Antioxidants> Examples of antioxidants include phenolic antioxidants, amine antioxidants, and phosphite antioxidants.

[0100] <Corrosion Inhibitors> Examples of corrosion inhibitors include benzotriazole, toltriazole, thiadiazole, and benzimidazole.

[0101] <Rust Inhibitors> Examples of rust inhibitors include metal sulfonate salt compounds and sorbitan compounds.

[0102] <Rheology Control Agent> In this disclosure, a rheology control agent refers to an additive that imparts non-Newtonian properties to changes in shear rate, and is an additive that provides flow characteristics such as increasing shear viscosity in the low shear rate range while decreasing shear viscosity in the high shear rate range.

[0103] The rheology control agent may be an inorganic compound-based rheology control agent or an organic compound-based rheology control agent. Examples of inorganic compound-based rheology control agents include fumed silica, bentonite, mica, and kaolin. Examples of organic compound-based rheology control agents include urea-modified polymers, urethane-modified polymers, castor oil wax, polyethylene wax, polyamide wax, and fatty acid amide wax. Among these, inorganic compound-based rheology control agents are preferred, with fumed silica or bentonite being more preferred, and bentonite being even more preferred. When using fumed silica, it is preferable to use one whose surface has been made hydrophobic by a silane coupling agent or other surface modifier. When using bentonite, organically modified bentonite using a quaternary ammonium salt or other organic modifier is preferably used.

[0104] There are no particular restrictions on the amount of rheology control agent contained, and it can be set as appropriate.

[0105] [Form of the curable composition] The curable composition according to this disclosure is preferably a one-component curable composition that uses one type of curable composition when applied to a substrate, heating element, etc. The curable composition according to this disclosure may also be a two-component curable composition that uses two types of curable compositions mixed together.

[0106] [Method for Manufacturing the Curable Composition] The method for manufacturing the curable composition according to this disclosure is not particularly limited. The curable composition according to this disclosure can be manufactured, for example, by the following method. In one embodiment, the curable composition according to this disclosure is obtained by placing a thermally conductive filler, monomers M1 and M2, a polymerization initiator, a dispersant, a plasticizer, and other additives into a stirring vessel and stirring and mixing them. Known stirrers and the like can be used for stirring and mixing.

[0107] In the method for producing a curable composition, when other additives are added, stirring is sufficient for a period of time during which the other additives can dissolve or disperse. The other additives may be added to the stirring container together with the other components, or they may be added after the other components have been mixed.

[0108] (Cured product) The cured product according to this disclosure is a cured product of the curable composition according to this disclosure. The method for curing the curable composition is not limited and can be appropriately selected from commonly used methods. Examples of curing methods include irradiation with active energy rays and heating, but curing by heating is preferred. When curing the curable composition according to this disclosure by heating, the heating temperature is preferably 60°C or higher, and more preferably 70°C or higher. The heating time is preferably 1 minute to 120 minutes.

[0109] Furthermore, the curable composition relating to this disclosure may be cured by reacting with moisture in the air, or by curing at room temperature.

[0110] The thermal conductivity of the cured product according to this disclosure is preferably 0.5 (W・m / K) to 50 (W・m / K), more preferably 1 (W・m / K) to 20 (W・m / K), and even more preferably 3 (W・m / K) to 20 (W・m / K), from the viewpoint of flexibility, shape stability, and suppression of changes in thermal conductivity.

[0111] The adhesive properties of the cured product according to this disclosure are preferably such that the tensile shear stress measured in accordance with JIS K 6850:1999 is 0.5 MPa or higher, more preferably 0.55 MPa or higher, and even more preferably 0.6 MPa or higher. The upper limit of the tensile shear stress is not particularly limited, but for example it may be 5 MPa.

[0112] Regarding the flexibility of the cured product according to this disclosure, from the viewpoint of stress relief to surrounding parts of the cured product, the Shore DO hardness measured in accordance with ASTM D2240 is preferably 85 or less, and more preferably 80 or less. As for the lower limit, for the reason of preventing pump-out, it is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more.

[0113] Shore DO hardness is a value measured using a spring-type hardness tester such as a durometer (registered trademark), and is the value measured immediately after pressing the hardness tester against the object being measured.

[0114] <Applications> The curable composition according to this disclosure can be suitably used, for example, as a TIM (Thermal Insulation Material) to fill recesses (gaps between heat-generating and heat-dissipating elements) formed in a substrate. The cured product obtained from the curable composition according to this disclosure has excellent adhesion and flexibility, and can follow thermal expansion and contraction, thus efficiently dissipating heat, making it suitable for use as a gap filler.

[0115] Next, the curable composition and cured product relating to this disclosure will be specifically described with reference to examples. However, the curable composition and cured product relating to this disclosure are not limited in any way by these examples.

[0116] (Examples 1-6 and Comparative Examples 1-8) Each component listed in the composition column of Table 1 or Table 2 was blended in the amounts listed in Table 1 or Table 2, and the mixture was mixed at 2,000 rpm (revolutions per minute) for 2 minutes under atmospheric pressure using a rotational / revolving mixer (manufactured by Thinky Co., Ltd., product name: Awatori Rentaro ARV-310) to prepare a curable composition.

[0117] Details of each component listed in Table 1 or Table 2 are as follows:

[0118] <Thermally conductive fillers> Zinc oxide 1: Zinc oxide type 1, volume average diameter D50; 0.6 μm (Sakai Chemical Industry Co., Ltd.) Zinc oxide 2: Calcined zinc oxide DW-4 (4 μm) (Hakusui Tech Co., Ltd.) Zinc oxide 3: Calcined zinc oxide surface treated product (12 μm) (Hakusui Tech Co., Ltd.)

[0119] <Monomer-M1> (Monomer-M1a) 2-(allyloxymethyl)methyl acrylate: AOMA (Nippon Shokubai Co., Ltd.) (Monomer-M1b) Tetrahydrofurfuryl acrylate: THFA (Tokyo Chemical Industries, Ltd.) Tetrahydrofurfuryl methacrylate: THFMA (Tokyo Chemical Industries, Ltd.)

[0120] <Monomer-M2> Decyltetradecanol monomethacrylate: NK ester ITEC (Shin Nakamura Chemical Industry Co., Ltd.) Lauryl methacrylate: Light ester L (Kyoeisha Chemical Co., Ltd.) 2-hydroxylethyl methacrylate: Light ester HO-250 (N) (Kyoeisha Chemical Co., Ltd.) 2-ethylhexyl methacrylate: 2-EHMA (Mitsubishi Gas Chemical Co., Ltd.) 2-hydroxypropyl methacrylate: HPMA (Nippon Shokubai Co., Ltd.) 2-hydroxylbutyl methacrylate: Light ester HOB (n) (Kyoeisha Chemical Co., Ltd.) 2-methacryloyloxyethyl succinate: Light ester HO-MS (N) (Kyoeisha Chemical Co., Ltd.) Isobornyl acrylate: Isobornyl acrylate (Daicel Ornex Co., Ltd.) Polypropylene glycol #400 dimethacrylate: 9PG (Shin Nakamura Chemical Industry Co., Ltd.)

[0121] <Dispersant> Oleic acid: Oleic acid (NOF Co., Ltd.) <Polymerization initiator> 1,1,3,3,-tetramethylbutylperoxy-2-ethylhexanoate: Perocta-O (NOF Co., Ltd.) <Plasticizer> Trimellitus mixed linear alkyl ester: C-880 NB (manufactured by ADEKA Corporation) <Rheology control agent> Organically modified bentonite: CLAYTONE-40 (BIC CHEMI Japan Co., Ltd.) <Coloring pigment> Copper phthalocyanine: Cyanine Blue 4920 (Dainichi Seika Kogyo Co., Ltd.)

[0122] In the composition column of Tables 1 and 2, a blank space indicates that the component in question is not present. In Tables 1 and 2, "thermal conductive filler filling rate" refers to the percentage (mass%) of the mass of thermal conductive filler relative to the total amount of curable composition. In Tables 1 and 2, "binder component" refers to the liquid component in the curable composition, including monomers, dispersants, polymerization initiators, and plasticizers. In Tables 1 and 2, "-" indicates that the corresponding value cannot be calculated.

[0123] -Evaluation- The following evaluations were performed using the obtained curable composition.

[0124] <Tensile Shear Stress: Adhesion> The tensile shear stress of the curable composition was measured in accordance with JIS K 6850:1999. Two aluminum plates (A1050P-H24) measuring 25 mm wide x 100 mm long x 1.6 mm thick were prepared. The two aluminum plates were bonded together using the curable composition, with an adhesive area of ​​25 mm wide x 12.5 mm long x 250 μm thick. The curable composition was then cured at 80°C for 30 minutes. Next, each of the two aluminum plates was pulled in the shear direction at a tensile speed of 10 mm / min using a tensile testing machine (product name: MX2-1000N-FA, manufactured by IMADA Co., Ltd.), and the tensile shear stress was calculated from the measured maximum strength. The measurement results are shown in Table 1 or Table 2. If the tensile shear stress was 0.5 MPa or higher, this evaluation was judged to be a pass.

[0125] <Hardness: Flexibility> - Softness after curing: Shore DO hardness - The curable composition was molded to 50 mm x 20 mm x 6 mm (thickness 6 mm), and a cured product was obtained after curing at 80°C for 30 minutes. The softness of the obtained cured product was measured using a durometer (product name: GS-752G, manufactured by Teclock Co., Ltd.) in accordance with ASTM D 2240. The measurement results are shown in Table 1 or Table 2. If the Shore DO hardness was 85 or less, this evaluation was judged to be a pass.

[0126] <Compatibility> The binder component (i.e., the liquid component in the curable composition, including monomers, dispersants, polymerization initiators, and plasticizers) was mixed with other components to evaluate its compatibility. If it was mixable, the evaluation was deemed to be successful. The results are shown in Table 1 or Table 2, with "OK" indicating that it was mixable and "NG" indicating that it was not mixable.

[0127] <Overall Evaluation (Performance Pass / Fail)> If all three evaluation items—tensile shear stress, hardness, and compatibility—pass, the overall evaluation (performance pass / fail) was determined to be a pass. The results are shown in Table 1 or Table 2.

[0128]

[0129]

[0130] As shown in Table 1, the cured products obtained from the curable compositions of the examples exhibited excellent adhesion and flexibility. In contrast, as shown in Table 2, the curable compositions of the comparative examples failed to meet the standards for either adhesion or flexibility, failing to achieve both.

[0131] The disclosure of Japanese Patent Application No. 2025-031664, filed on 28 February 2025, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A curable composition comprising a thermally conductive filler, monomer M1, monomer M2, polymerization initiator, and dispersant, wherein monomer M1 comprises a monomer represented by the following formula 1, and monomer M2 comprises a monomer consisting of a (meth)acryloyl group and a residue that does not have a heterocyclic structure (however, monomer M2 does not contain the monomer represented by the following formula 1). In formula 1, R １ ~R １０ Each of these independently represents a hydrogen atom or an organic group.

2. A curable composition comprising a thermally conductive filler, monomer M1, monomer M2, polymerization initiator, and dispersant, wherein monomer M1 comprises a monomer consisting of a (meth)acryloyl group and a residue having a heterocyclic structure, and monomer M2 comprises a monomer consisting of a (meth)acryloyl group and a residue not having a heterocyclic structure (however, monomer M2 does not contain the monomer represented by the following formula 1). In formula 1, R １ ~R １０ Each of these independently represents a hydrogen atom or an organic group.

3. In formula 1, R １ R represents the group shown in the following formula 2, ２ ~R １０ The curable composition according to claim 1, wherein each of these terms represents a hydrogen atom. In equation 2, * indicates the bonding position.

4. The curable composition according to any one of claims 1 to 3, wherein the content of monomer M1 is 5% by mass or more and 35% by mass or less on a mass basis, relative to the total content of monomer M1 and monomer M2.

5. The curable composition according to any one of claims 1 to 3, wherein the content of monomer M1 is 10% by mass or more and 30% by mass or less on a mass basis, relative to the total content of monomer M1 and monomer M2.

6. The curable composition according to claim 1 or claim 2, wherein in monomer M2, the residue that does not have a heterocyclic structure is an organic group with a total of 12 or more carbon atoms.

7. The curable composition according to claim 1 or claim 2, wherein the thermally conductive filler comprises zinc oxide.

8. A cured product of the curable composition according to claim 1 or claim 2.

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