Curable composition, cured product thereof, and curability improver

Abstract

Disclosed is a curable composition which contains: a polymerizable compound (A) that has a condensed polycyclic hydrocarbon structure and two or more polymerizable functional groups which are bonded to the condensed polycyclic hydrocarbon structure; and a polymerizable compound (B) that has a condensed polycyclic hydrocarbon structure and two or more maleimide groups which are bonded to the condensed polycyclic hydrocarbon structure. The polymerizable compound (A) and the polymerizable compound (B) comprise the same condensed polycyclic hydrocarbon structure.

Description

Curable composition, cured product thereof, and curability enhancer

[0001] The present invention relates to a curable composition, a cured product thereof, and a curability enhancer.

[0002] Tricyclodecane dimethanol diacrylate (hereinafter sometimes referred to as "TCD-DA") is liquid at room temperature, and its cured product exhibits a high glass transition temperature (Tg), low water absorption, flexibility, etc. Therefore, TCD-DA is used as a raw material for various resin materials such as coating materials, optical lenses, and dental materials. Several technologies using TCD-DA have been proposed (see, for example, Patent Documents 1 and 2 listed below).

[0003] JP 2012-177877 A International Publication No. WO2017 / 170252 A

[0004] When a cured product made from TCD-DA is used in the above-mentioned applications, it is generally preferable that the surface of the cured product is free of tack (stickiness). However, in order to completely cure (polymerize) TCD-DA with light, a large integrated light dose is required, leaving room for improvement in terms of productivity and energy efficiency. Furthermore, while TCD-DA may be used in combination with other polymerizable compounds, problems such as a reduced pot life of the curable resin composition, reduced flexibility of the cured product, and reduced transparency due to residual crystals or phase separation in the cured product may arise. For this reason, there is a need for the development of a technology that utilizes the advantages of TCD-DA while improving the ease of curing TCD-DA in the atmosphere (i.e., in an oxygen atmosphere) (hereinafter, sometimes referred to as "curability").

[0005] In order to solve the above-mentioned problems, an object of the present invention is to provide a curable composition having excellent curability, a cured product thereof, and a curability improver.

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that the above-mentioned problems can be solved by using a polymerizable compound (A) such as TCD-DA in combination with a polymerizable compound (B) having a basic skeleton common to that compound and having a maleimide group, thereby completing the present invention.

[0007] <1> A curable composition comprising: a polymerizable compound (A) having a condensed polycyclic hydrocarbon structure and two or more polymerizable functional groups bonded to the condensed polycyclic hydrocarbon structure; and a polymerizable compound (B) having a condensed polycyclic hydrocarbon structure and two or more maleimide groups bonded to the condensed polycyclic hydrocarbon structure, wherein the polymerizable compound (A) and the polymerizable compound (B) have the same condensed polycyclic hydrocarbon structure. <2> The curable composition according to <1>, wherein the condensed polycyclic hydrocarbon structure of the polymerizable compound (A) and the condensed polycyclic hydrocarbon structure of the polymerizable compound (B) are aliphatic condensed polycyclic hydrocarbon structures. <3> The curable composition according to <1> or <2>, wherein at least one of the two or more polymerizable functional groups of the polymerizable compound (A) is a group having an ethylenically unsaturated double bond. <4> The curable composition according to any one of <1> to <3>, wherein the polymerizable compound (A) includes a compound represented by the following formula (I): (In formula (I), R 1 , R 2 each independently represent H or CH3, and n and m each independently represent an integer of 1 to 3. <5> The curable composition according to any one of <1> to <4>, wherein the polymerizable compound (B) contains a compound represented by the following formula (II): (In formula (II), o, p, q, and r each independently represent an integer of 1 to 3.) <6> The curable composition according to any one of <1> to <5> above, which contains a filler. <7> A curability improver containing a compound represented by the following formula (II): (In formula (II), o, p, q, and r each independently represent an integer of 1 to 3.) <8> A cured product obtained by curing the curable composition according to any one of <1> to <6> above.

[0008] According to the present invention, it is possible to provide a curable composition having excellent curability, a cured product thereof, and a curability enhancer.

[0009] The present invention will be described below, but the contents of the present invention are not limited to the following description. Furthermore, throughout this specification, the term "(meth)acrylate" or the like means "acrylate" or "methacrylate", the term "alkyl(meth)acrylate" or the like means "alkyl acrylate" or "alkyl methacrylate", and the term "(meth)acryloyl" means "acryloyl" or "methacryloyl". Furthermore, unless otherwise specified, the term "alkyl group" includes alkyl groups of linear, branched, and alicyclic structures. Furthermore, when a numerical range is indicated using "to" (a number), the range includes both ends of the range.

[0010] <<Curable Composition>> The curable composition of the present embodiment includes a polymerizable compound (A) having a condensed polycyclic hydrocarbon structure and two or more polymerizable functional groups bonded to the condensed polycyclic hydrocarbon structure, and a polymerizable compound (B) having a condensed polycyclic hydrocarbon structure and two or more maleimide groups bonded to the condensed polycyclic hydrocarbon structure, wherein the polymerizable compound (A) and the polymerizable compound (B) have the same condensed polycyclic hydrocarbon structure.

[0011] The curable composition of this embodiment can improve its curability in the atmosphere by using a polymerizable compound (A) in combination with a polymerizable compound (B) having a maleimide group. While the mechanism by which the combined use of polymerizable compounds (A) and (B) results in curability in the atmosphere is unclear, it is speculated that because maleimide groups are relatively susceptible to generating radicals when exposed to ultraviolet light, the polymerization reaction prevails over the influence of oxygen inhibition, even in the atmosphere, resulting in improved curability. Thus, the polymerizable composition of this embodiment can form a cured product with a lower integrated light dose than when using only conventional TCD-DA, particularly in an oxygen atmosphere such as the atmosphere. Therefore, the polymerizable composition of this embodiment has excellent productivity and energy efficiency during curing. Furthermore, the polymerizable composition of this embodiment can suppress the occurrence of cracks in the resulting cured product, resulting in excellent moldability (crackless). Furthermore, compounds having a maleimide group are relatively rigid compared to compounds having a (meth)acryloyl group. Generally, the more rigid the molecular structure, the harder the compound, which can increase the glass transition temperature (Tg) of the cured product. On the other hand, since the carbon chain from the condensed polycyclic hydrocarbon structure to both terminal functional groups is relatively long, it is highly mobile and can impart flexibility to the cured product. Therefore, the polymerizable composition of this embodiment can provide a cured product that has a relatively high Tg and excellent flexural modulus (flexibility).

[0012] In addition, the curable composition of this embodiment can mitigate the effects of cure shrinkage. For example, because maleimide groups have relatively low reactivity to heat, adding a polymerizable compound (B) having a maleimide group to the polymerizable compound (A) allows the reaction of the polymerizable composition to proceed more slowly than when TCD-DA alone is thermally cured. This is presumably mitigating the occurrence of distortion associated with rapid cure shrinkage. Furthermore, for example, using a polymerizable compound (B) with a large molecular weight relative to a polymerizable compound (A) such as TCD-DA reduces the amount of substance per unit mass, thereby reducing the number of C-C bonds per unit mass generated by polymerization. This is presumably suppressing the effects of cure shrinkage and thereby suppressing the occurrence of cracks in the cured product.

[0013] In this embodiment, the polymerizable compound (A) and the polymerizable compound (B) contain the same condensed polycyclic hydrocarbon structure. Therefore, the polymerizable compounds (A) and (B) have excellent compatibility (hereinafter sometimes simply referred to as "compatibility"), allowing the amount of solvent used in the curable composition of this embodiment to be reduced or the two compounds to be mixed without using a solvent. Furthermore, the excellent compatibility of the polymerizable compounds (A) and (B) can suppress crystalline precipitation and phase separation in the cured product, thereby improving the transparency of the cured product. Furthermore, a composite material obtained from a curable composition containing the polymerizable compounds (A) and (B) having a tricyclodecane structure or the like and a filler (C) such as inorganic particles can have excellent heat resistance (low linear expansion coefficient) and moldability (crackless).

[0014] <Polymerizable Compound (A)> The polymerizable compound (A) has a condensed polycyclic hydrocarbon structure and two or more polymerizable functional groups bonded to the condensed polycyclic hydrocarbon structure. In other words, the polymerizable compound (A) is a condensed polycyclic hydrocarbon compound having two or more polymerizable functional groups. As described above, the polymerizable compound (A) and the polymerizable compound (B) contain the same condensed polycyclic hydrocarbon structure. Here, "containing the same condensed polycyclic hydrocarbon structure" means that the polymerizable compounds (A) and (B) have a common condensed polycyclic hydrocarbon structure. However, in each condensed polycyclic hydrocarbon structure, the carbon atoms to which the polymerizable functional group or maleimide group is bonded may be the same or different.

[0015] The condensed polycyclic hydrocarbon structure may be an aliphatic condensed polycyclic hydrocarbon structure or an aromatic condensed polycyclic hydrocarbon structure. The condensed polycyclic hydrocarbon structure of the polymerizable compound (A) and the condensed polycyclic hydrocarbon structure of the polymerizable compound (B) are preferably aliphatic condensed polycyclic hydrocarbon structures. Examples of the aliphatic condensed polycyclic hydrocarbon structure include a bicyclopentane structure, a bicycloheptane structure, a bicyclooctane structure, and other tricyclo[5.2.1.0(2,6)]decane structure, an adamantane structure, a tricyclo[4.3.1.1(3,8)]undecane structure, a tricyclo[6.2.1.0(1,6)]undecane structure, and other tricyclic aliphatic condensed polycyclic hydrocarbon structures. The number of carbon atoms in the aliphatic condensed polycyclic hydrocarbon structure is preferably 8 to 24, more preferably 10 to 20, and particularly preferably 12 to 16, from the viewpoints of the heat resistance (hereinafter simply referred to as heat resistance) and compatibility of the resulting cured product. From the viewpoints of the heat resistance and compatibility of the resulting cured product, the aliphatic condensed polycyclic hydrocarbon structure is preferably a tricyclic aliphatic condensed polycyclic hydrocarbon structure, more preferably a tricyclodecane structure, and particularly preferably a tricyclo[5.2.1.0(2,6)]decane structure. Examples of aromatic condensed polycyclic hydrocarbon structures include bicyclic aromatic condensed polycyclic hydrocarbon structures such as an indene structure, a naphthalene structure, and an azulene structure; tricyclic aromatic condensed polycyclic hydrocarbon structures such as an anthracene structure and a phenanthrene structure; and tetracyclic aromatic condensed polycyclic hydrocarbon structures such as a naphthacene structure, a triphenylene structure, a pyrene structure, and a chrysene structure. From the viewpoints of heat resistance and compatibility, the number of carbon atoms in the aromatic condensed polycyclic hydrocarbon structure is preferably 8 to 32, more preferably 10 to 24, and particularly preferably 12 to 16. From the viewpoints of heat resistance and compatibility, the aromatic condensed polycyclic hydrocarbon structure is preferably a bicyclic aromatic condensed polycyclic hydrocarbon structure, and more preferably a naphthalene structure.

[0016] The polymerizable compound (A) has two or more polymerizable functional groups. The number of polymerizable functional groups is not particularly limited as long as it is two or more, but from the viewpoint of being able to lower the linear expansion coefficient of the cured product to a certain degree while increasing the flexural modulus to a certain degree, the number of polymerizable functional groups is preferably 2 to 4, more preferably 2 to 3, and particularly preferably 2.

[0017] The "polymerizable functional group" of the polymerizable compound (A) refers to a functional group having polymerizability other than a functional group containing a maleimide group (including the maleimide group itself). Examples of the polymerizable functional group of the polymerizable compound (A) include a group having an ethylenically unsaturated double bond and an epoxy group. Preferably, at least one of the two or more polymerizable functional groups contained in the polymerizable compound (A) is a group having an ethylenically unsaturated double bond, and more preferably, two or more polymerizable functional groups are groups having an ethylenically unsaturated double bond. Examples of the group having an ethylenically unsaturated double bond include a (meth)acryloyl group, a vinyl group, an allyl group, and groups containing these. More preferred are a (meth)acryloyl group, an allyl group, and groups containing these, and particularly preferred is a (meth)acryloyl group. Furthermore, the polymerizable compound (A) may contain other groups other than the above-mentioned polymerizable functional groups on the condensed polycyclic hydrocarbon structure. Examples of other groups include an alkyl group, a halogenated alkyl group, and the like.

[0018] In the polymerizable compound (A), the condensed polycyclic hydrocarbon structure and the polymerizable functional group may be bonded directly or via another atom or atomic group. Examples of the other atom or atomic group include an oxygen atom, a nitrogen atom, a sulfur atom, an alkylene group which may have a substituent, and an arylene group. From the viewpoint of heat resistance, the other atom or atomic group is preferably an alkylene group having 1 to 5 carbon atoms, and more preferably an alkylene group having 1 to 3 carbon atoms.

[0019] The polymerizable compound (A) can contain a compound represented by the following formula (I): There may be two or more types of compounds represented by the following formula (I); in other words, the polymerizable compound (A) can contain two or more types of compounds represented by the following formula (I): Examples of combinations of two or more types of compounds represented by the following formula (I) include combinations of compounds in which n and m are the same in each compound (however, n and m within a single compound may be different) and the bonding sites between the condensed polycyclic hydrocarbon structure (tricyclo[5.2.1.0(2,6)]decane structure) and the group containing the polymerizable functional group ((meth)acryloyl group) are different.

[0020] (In formula (I), R 1 , R 2 each independently represents H or CH3, and n and m each independently represents an integer of 1 to 3.

[0021] In formula (I), R 1 , R 2 each independently represents H or CH3, and CH3 is preferred from the viewpoint of the moldability described above. In addition, in formula (I), n and m each independently represent an integer of 1 to 3, and from the viewpoint of heat resistance, each is preferably 1 or 2, and more preferably 1. Examples of compounds represented by formula (I) include tricyclodecane dimethanol diacrylate (TCD-DA), tricyclodecane dimethanol dimethacrylate (TCD-DMA), etc.

[0022] The polymerizable compound (A) may be a single compound or a combination of two or more compounds. When the polymerizable compound (A) contains two or more compounds, for example, a combination of polymerizable compounds (A) having the same condensed polycyclic hydrocarbon structure, a combination of polymerizable compounds (A) having the same polymerizable functional group, or a combination of polymerizable compounds (A) having the same condensed polycyclic hydrocarbon structure and the same polymerizable functional group can be mentioned. Among these, a combination of polymerizable compounds (A) having the same condensed polycyclic hydrocarbon structure and the same polymerizable functional group is preferred. An example of a "combination of polymerizable compounds (A) having the same condensed polycyclic hydrocarbon structure and the same polymerizable functional group" is a combination of polymerizable compounds (A) having the same condensed polycyclic hydrocarbon structure and the same polymerizable functional group, where the bonding positions of the polymerizable functional groups on the condensed polycyclic hydrocarbon structure in each of the same condensed polycyclic hydrocarbon structures are different. Furthermore, when the polymerizable compound (A) contains two or more compounds having the same polymerizable functional group, the polymerizable functional group and the condensed polycyclic hydrocarbon structure of each polymerizable compound (A) may be bonded via a direct bond and via another atom (or atomic group), and compounds in which the polymerizable functional group and the condensed polycyclic hydrocarbon structure of each polymerizable compound (A) are bonded together may be present. When the polymerizable compound (A) contains two or more compounds, a preferred embodiment is a combination of polymerizable compounds (A) having the same condensed polycyclic hydrocarbon structure and the same polymerizable functional group, in which the bond between the polymerizable functional group and the condensed polycyclic hydrocarbon structure of each polymerizable compound (A) is the same, and the bonding position of the polymerizable functional group on the condensed polycyclic hydrocarbon structure in each condensed polycyclic hydrocarbon structure is different.

[0023] The polymerizable compound (A) is preferably liquid under atmospheric pressure and at room temperature, and preferably has a glass transition temperature (Tg) of 100° C. or higher from the viewpoint of heat resistance of the cured product.

[0024] The glass transition temperature (Tg) of the polymerizable compound (A) can be measured by the following method. A monomer and a polymerization initiator are injected into a mold (two glass plates, each with a release film attached, with the release film surfaces facing each other, between which a 4 mm thick silicone spacer is used to form an area 100 mm long and 100 mm wide, with the silicone spacer sandwiched between the two glass plates so that the gap is approximately 2 to 4 mm). The mold is irradiated with ultraviolet light (wavelength: 365 nm) using an LED exposure device for 1 hour to obtain a polymer.

[0025] 10 mg of the obtained polymer was weighed out and attached to a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Corporation). Measurement was performed at a heating rate of 10°C / min in a temperature range of -130 to 100°C. The temperature of the endothermic peak attributable to the polymer during the first heating process was taken as the glass transition temperature (Tg) of the polymer, which was also taken as the Tg of the monomer (polymerizable compound (A)). The Tg of the polymerizable compound (B) described below and the Tg of the cured product can also be measured and determined in the same manner.

[0026] From the viewpoint of setting the viscosity of the curable composition within a range that allows easy handling, the content of the polymerizable compound (A) in the curable composition is preferably 40 to 93 mass %, more preferably 50 to 85 mass %, and particularly preferably 60 to 75 mass %, relative to the total amount of the composition.

[0027] The method for synthesizing the polymerizable compound (A) is not particularly limited, but for example, the polymerizable compound (A) can be synthesized by reacting a compound corresponding to a condensed polycyclic hydrocarbon structure having two or more hydroxyl groups in one molecule with a carboxylic acid or the like having a polymerizable functional group.

[0028] <Polymerizable Compound (B)> The polymerizable compound (B) has a condensed polycyclic hydrocarbon structure and two or more maleimide groups bonded to the condensed polycyclic hydrocarbon structure. In other words, the polymerizable compound (B) is a condensed polycyclic hydrocarbon compound having two or more maleimide groups. As described above, the condensed polycyclic hydrocarbon structure of the polymerizable compound (B) and the condensed polycyclic hydrocarbon structure of the polymerizable compound (A) contain the same condensed polycyclic hydrocarbon structure.

[0029] The condensed polycyclic hydrocarbon structure of the polymerizable compound (B) may be an aliphatic condensed polycyclic hydrocarbon structure or an aromatic condensed polycyclic hydrocarbon structure, and is preferably an aliphatic condensed polycyclic hydrocarbon structure. Examples and preferred ranges of the condensed polycyclic hydrocarbon structure are the same as those of the polymerizable compound (A) described above.

[0030] The polymerizable compound (B) has two or more maleimide groups. There are no particular limitations on the number of maleimide groups as long as it is two or more, but from the viewpoint of being able to lower the linear expansion coefficient of the cured product to a certain degree while increasing the flexural modulus to a certain degree, 2 to 4 maleimide groups are preferred, 2 to 3 are more preferred, and 2 is particularly preferred. The polymerizable compound (B) may contain a group other than the above-mentioned polymerizable functional group on the condensed polycyclic hydrocarbon structure. Examples of such a group include an alkyl group and a halogenated alkyl group.

[0031] In the polymerizable compound (B), the condensed polycyclic hydrocarbon structure and the polymerizable functional group may be bonded directly or via another atom or atomic group. Examples and preferred ranges of the other atom or atomic group in the polymerizable compound (B) are the same as those in the polymerizable compound (A) described above.

[0032] The method for synthesizing the polymerizable compound (B) is not particularly limited, but for example, the polymerizable compound (B) can be synthesized by reacting a compound corresponding to a condensed polycyclic hydrocarbon structure having two or more hydroxyl groups in one molecule with a carboxylic acid having a maleimide group or the like.

[0033] The polymerizable compound (B) can contain a compound represented by the following formula (II). There can be two or more types of compounds represented by the following formula (II). In other words, the polymerizable compound (B) can contain two or more types of compounds represented by the following formula (II). Examples of combinations of two or more types of compounds represented by the following formula (II) include combinations of compounds in which o, p, q, and r of each compound are the same (however, o, p, q, and r within a single compound may be different) and the bonding sites of the condensed polycyclic hydrocarbon structure (tricyclo[5.2.1.0(2,6)]decane structure) and the group containing a maleimide group are different.

[0034] (In formula (II), o, p, q, and r each independently represent an integer of 1 to 3.)

[0035] In formula (I), o, p, q, and r each independently represent an integer of 1 to 3, and from the viewpoint of the heat resistance of the cured product, preferably represent 1 or 2, more preferably 1. An example of the compound represented by formula (II) is tricyclodecane dimethanol dimaleimide (hereinafter, sometimes referred to as "TCD-DMI").

[0036] Like the polymerizable compound (A), the polymerizable compound (B) may be a single compound or a combination of two or more compounds. When the polymerizable compound (B) contains two or more compounds, examples of the polymerizable compound (B) include a combination of polymerizable compounds (B) having the same condensed polycyclic hydrocarbon structure, a combination of polymerizable compounds (B) having the same "maleimide group-containing group", or a combination of polymerizable compounds (B) having the same condensed polycyclic hydrocarbon structure and the same "maleimide group-containing group". Among these, a combination of polymerizable compounds (B) having the same condensed polycyclic hydrocarbon structure and the same "maleimide group-containing group" is preferred. An example of a "combination of polymerizable compounds (B) having the same condensed polycyclic hydrocarbon structure and the same "maleimide group-containing group" is a combination of polymerizable compounds (B) having the same condensed polycyclic hydrocarbon structure and the same "maleimide group-containing group", where the bonding positions of the maleimide group-containing group on each of the same condensed polycyclic hydrocarbon structures are different. Furthermore, when the polymerizable compound (B) contains two or more compounds each having the same maleimide group-containing group, the maleimide group-containing group and the fused polycyclic hydrogen structure of each polymerizable compound (B) may be bonded via a direct bond and via another atom (or atomic group) in a mixture of these compounds. When the polymerizable compound (B) contains two or more compounds, a preferred embodiment is a combination of polymerizable compounds (B) each having the same fused polycyclic hydrocarbon structure and the same maleimide group-containing group, and a combination of polymerizable compounds (B) each having the same bond between the maleimide group-containing group and the fused polycyclic hydrogen structure of each polymerizable compound (B), but in which the bonding position of the maleimide group-containing group on the fused polycyclic hydrocarbon structure in each fused polycyclic hydrocarbon structure is different.

[0037] The polymerizable compound (B) is preferably liquid under atmospheric pressure and at room temperature, and preferably has a glass transition temperature (Tg) of 100° C. or higher from the viewpoint of heat resistance.

[0038] From the viewpoint of setting the viscosity of the curable composition within a range that allows easy handling, the content of the polymerizable compound (B) in the curable composition is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and particularly preferably 40 parts by mass or less, relative to 100 parts by mass of the total amount of the composition.

[0039] From the viewpoint of transparency of the cured product, the polymerizable compound (B) is preferably soluble in the polymerizable compound (A). In the curable composition of the present embodiment, when the polymerizable compound (B) is soluble in the polymerizable compound (A) (i.e., when the polymerizable compound (A) and the polymerizable compound (B) are compatible with each other), the curable composition can be formed without using a solvent or with a reduced content of the solvent. From the viewpoint of improving the transparency of the curable composition, the solubility of the polymerizable compound (B) in 100 g of the polymerizable compound (A) (under 1 atmosphere, at a liquid temperature of 25° C.) is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 100% by mass or more, and particularly preferably 150% by mass or more, although it is not particularly limited. When the solubility of the compound (B) is 100% by mass or more, the amount of solvent in the composition can be less than 5% by mass. The solubility can be confirmed, for example, by adding the polymerizable compound (B) dropwise to 10 g of the polymerizable compound (A), heating and mixing at 50°C, and visually inspecting the state after cooling. The polymerizable compound (B) is added dropwise, for example, in 0.5 g increments, and the upper limit concentration at which no insoluble matter is visually observed after cooling and a homogeneous solution is obtained can be taken as the solubility of the polymer. For example, the solubility of a solution in which no insoluble matter is observed when 1 g of the polymerizable compound (B) is dissolved, but insoluble matter is observed when 1.5 g of the polymerizable compound (B) is dissolved, is 10% by mass.

[0040] From the viewpoint of curability, the total amount of the polymerizable compound (A) and the polymerizable compound (B) in the composition of the present embodiment is preferably 10 parts by mass or more, more preferably 40 parts by mass or more, and particularly preferably 70 parts by mass or more, relative to 100 parts by mass of the total amount of the composition.

[0041] <Polymerization initiator> In the composition of the present embodiment, a polymerization initiator can be used when polymerizing each of the above-described polymerizable compounds by, for example, a polymerization method shown in the production method described later. Examples of the polymerization initiator include known photopolymerization initiators and thermal polymerization initiators.

[0042] Photopolymerization initiator: Examples of the photopolymerization initiator include a radical photopolymerization initiator, a cationic photopolymerization initiator, and an anionic photopolymerization initiator. These photopolymerization initiators may be used alone or in combination of two or more. For example, two or more radical photopolymerization initiators may be used in combination.

[0043] Examples of the radical photopolymerization initiator include the following compounds: Acylphosphine oxide compounds: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (product name: Irgacure TPO, manufactured by BASF), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (product name: Irgacure 819, manufactured by BASF; product name: Irgacure 819DW, manufactured by BASF).

[0044] α-Hydroxyketone compounds: 1-hydroxycyclohexylphenyl ketone (product name: Irgacure 184, manufactured by BASF), 2-hydroxy-2-methyl-1-phenylpropan-1-one (product name: Irgacure 1173, manufactured by BASF), 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959, manufactured by BASF), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one (product name: Irgacure 127, manufactured by BASF)

[0045] Intramolecular hydrogen abstraction compound: phenyl glyoxylic acid methyl ester (product name: Irgacure MBF, manufactured by BASF) Titanocene compound: 1-[4-(phenylthio)-2-(o-benzoyloxime)], bis(η5-2,4-cyclopentadiene-1-yl)bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyltitanium] (product name: Irgacure 784, manufactured by BASF) Benzil ketal compound: 2,2-dimethoxy-1,2-diphenylethan-1-one (product name: Irgacure 651, manufactured by BASF)

[0046] α-Aminoketone compounds: 2-methyl-4'-methylthio-2-morpholinopropiophenone (product name: Irgacure 907, manufactured by BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: Irgacure 369, manufactured by BASF), 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone (product name: Irgacure 379EG, manufactured by BASF)

[0047] Oxime ester compounds such as 1-[4-(phenylthio)-2-(O-benzoyloxime)] (product name: Irgacure OXE-01, manufactured by BASF), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) (for example, product name: Irgacure OXE-02, manufactured by BASF; product name: Irgacure OXE-03, manufactured by BASF; product name: Irgacure OXE-04, manufactured by BASF; product name: N-1919, manufactured by ADEKA; and product name: N-1414, manufactured by ADEKA) can be used.

[0048] Other radical photopolymerization initiators include, for example, quinone compounds (e.g., 2-ethylanthraquinone, 2-tert-butylanthraquinone); aromatic ketones (e.g., benzophenone, benzoin); benzoin ether compounds (e.g., benzoin methyl ether, benzoin ethyl ether); acridine compounds (e.g., 9-phenylacridine (product name: N-1717, manufactured by ADEKA)); triazine compounds (e.g., 2,4-trichloromethyl-(4'-methoxyphenyl)-6-triazine, 2,4-trichloromethyl-(4'-methoxynaphthyl)-6-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one).

[0049] Examples of the cationic photopolymerization initiator include the following compounds: Iodonium salt compounds: diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, 4,4'-ditert-butyldiphenyliodonium tetrafluoroborate, (4-methylphenyl) [4-(2-methylpropyl) phenyl] iodonium hexafluorophosphate (product name: Irgacure 250, manufactured by BASF)

[0050] Diazonium salt compounds: 4-diethylaminophenylbenzenediazonium hexafluorophosphate, sulfonium salt compounds: diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, triarylsulfonium tetrakis-(pentafluorophenyl)borate (product name: Irgacure 290, manufactured by BASF), triarylsulfonium hexafluorophosphate (for example, product name: Irgacure 270, manufactured by BASF; product name: CPI300, manufactured by Sanyo Chemical Industries; product name: CPI400, manufactured by Sanyo Chemical Industries), ferrocenium salt compounds

[0051] Examples of anionic photopolymerization initiators include 2-(9-oxoxanthen-2-yl)propionic acid 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0052] A photosensitizer may be used in combination with the photopolymerization initiator. Examples of the photosensitizer include amines such as ethyl-4-dimethylaminobenzoate (Darocur EDB, manufactured by BASF) and 2-ethylhexyl-4-dimethylaminobenzoate (Darocur EHA, manufactured by BASF), and keto compounds such as benzophenones, thioxanthones, keto-coumarins, and anthraquinones (Anthracure UVS-581, manufactured by Kawasaki Chemical Industries, Ltd.).

[0053] -Thermal Polymerization Initiator- Examples of the thermal polymerization initiator include azo-based polymerization initiators such as dialkyl peroxides, dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobisisobutyronitrile (AIBN), dimethyl 2,2'-azobisisobutyrate, and azobisdimethylvaleronitrile, and peroxide-based polymerization initiators such as benzoyl peroxide, potassium persulfate, and ammonium persulfate, but the present embodiment is not limited to these examples. These polymerization initiators may be used alone, or two or more types may be used in combination.

[0054] In this embodiment, from the viewpoint of handleability in the atmosphere at low temperatures (for example, −20 to 40° C.), it is preferable to use a polymerization initiator that can be stored in a refrigerator, and for example, dialkyl peroxides such as Perbutyl O and Perbutyl P, which are commercially available from NOF Corporation, can be preferably used. The polymerization initiator can be used alone or in appropriate combination of two or more types.

[0055] From the viewpoint of moldability, the content of the polymerization initiator in the curable composition of the present embodiment is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 6 parts by mass, and particularly preferably 0.5 to 2 parts by mass, relative to 100 parts by mass of the total amount of the polymerizable compound components (total amount of the polymerizable compounds (A) and (B)).

[0056] <Filler (C)> When the curable composition of the present embodiment is used for sealing material applications, etc., it may contain a filler (C). Known fillers can be used as the filler (C), and examples of fillers that can be used include one or more materials selected from the group consisting of silica powders such as fused silica, synthetic silica, and crystalline silica; oxides such as alumina and titanium oxide; silicates such as talc, calcined clay, uncalcined clay, mica, and glass; carbonates such as calcium carbonate, magnesium carbonate, and hydrotalcite; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; sulfates or sulfites such as barium sulfate, calcium sulfate, and calcium sulfite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; and nitrides such as aluminum nitride, boron nitride, and silicon nitride.

[0057] The filler (C) is not particularly limited, but may be, for example, a silica powder such as fused silica. The fused silica may be either fused spherical silica or fused crushed silica. The fused silica may be one whose surface is modified with a functional group such as a (meth)acrylic group.

[0058] The shape of the filler (C) is not particularly limited and may be crushed, needle-like, scaly, spherical, or the like. From the viewpoint of improving the dispersibility of the filler (C) and controlling the viscosity of the curable composition, however, a spherical shape is preferred.

[0059] The average particle size of the filler (C) is preferably 0.1 μm to 20 μm, more preferably 0.2 μm to 5 μm, from the viewpoint of improving the packing density and controlling the viscosity of the curable composition. The average particle size in this embodiment is a median diameter calculated from the results of particle size distribution measurement by laser light diffraction. Furthermore, from the viewpoint of packing the filler at a high density in the curable composition, two or more types of fillers (C) having different volume average particle sizes may be contained.

[0060] When the filler (C) is used, the mass ratio of the polymerizable components (the total amount of the polymerizable compounds (A) and (B) to the total amount of the filler (C)) in the curable composition of the present embodiment is not particularly limited, but from the viewpoint of improving the heat resistance and flexural modulus of the resulting cured product, it is preferably 1:99 to 50:50, and more preferably 5:95 to 30:70. Furthermore, when two or more fillers (C) having different volume average particle sizes are contained, from the viewpoint of incorporating a large amount of filler (C) into the curable composition of the present embodiment, the mass ratio [A / B] of the filler [A] having a large volume average particle size to the filler [B] having a small volume average particle size is preferably 10 / 90 to 90 / 10, and more preferably 20 / 80 to 80 / 20.

[0061] <Others> In addition to the components described above, the curable composition of the present embodiment may contain a dispersant and a plasticizer, if necessary.

[0062] -Dispersant- The curable composition of the present embodiment may contain a dispersant to, for example, increase the dispersibility of the filler (C) in each polymerizable compound. The dispersant is not particularly limited, and known dispersants can be used, including, for example, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, polymeric surfactants, alcohols, compounds having a carboxy group such as fatty acids, metal soaps, fatty acid oligomer compounds, fluorine-based surfactants, and boron-based surfactants. One type of dispersant may be used, or two or more types may be used in combination.

[0063] When a dispersant is used, the content of the dispersant in the curable composition of the present embodiment is preferably 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and particularly preferably 1 to 2 parts by mass, relative to 100 parts by mass of the total amount of the filler (C), from the viewpoint of making it easy to adjust the viscosity of the curable composition to a range that is easy to handle.

[0064] -Plasticizer- The curable composition of the present embodiment may contain a plasticizer for the purpose of adjusting the flexibility of the cured product, etc. The plasticizer is not particularly limited, and examples thereof include polymers that are generally used as plasticizers, fatty acid ester compounds having an unsaturated hydrocarbon group, aromatic carboxylic acid ester compounds, as well as oils containing fatty acids and aromatic carboxylic acids having an unsaturated hydrocarbon group.

[0065] When a plasticizer is used, the content of the plasticizer in the curable composition of the present embodiment is preferably 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and particularly preferably 1 to 2 parts by mass, relative to 100 parts by mass of the total amount of the filler (C), from the viewpoint of the flexibility of the obtained cured product and the like.

[0066] Polymerization Inhibitor The curable composition of this embodiment may contain a polymerization inhibitor. The polymerization inhibitor is not particularly limited as long as it is a commonly used one, and examples thereof include 2,2,6,6-tetramethylpiperidine-1-oxyl derivatives such as 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (BTOX), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl (AMX); aromatic amine compounds such as phenothiazine; and alkylphenols such as 4-methoxyphenol and 2,6-di-tert-butyl-p-cresol (BHT).

[0067] When a polymerization inhibitor is used, the content of the polymerization inhibitor in the curable composition of the present embodiment is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and particularly preferably 0.7 to 1.5 parts by mass, relative to 100 parts by mass of the total amount of polymerizable compound components (the total amount of polymerizable compounds (A) and (B); if the curable composition contains polymerizable compounds other than the polymerizable compound (A) and the polymerizable compound (B)), in order to prevent unintended reactions (polymerization) of the curable composition while not inhibiting the polymerization reaction when producing a cured product.

[0068] -Solvent- The curable composition of this embodiment may contain a solvent. However, when the curable composition of this embodiment contains a solvent, the content of the solvent is preferably 10 mass % or less, more preferably 5 mass % or less, and even more preferably 1 mass % or less, relative to the total mass of the composition. It is particularly preferable that the composition does not contain a solvent. As described above, the polymerizable compound (A) and the polymerizable compound (B) may be compatible with each other, but the polymerizable compounds do not correspond to the solvent in this embodiment.

[0069] The solvent that can be used in the curable composition of the present embodiment is not particularly limited as long as it can dissolve the polymerizable compound (B) and the polymerizable compound (A) in the present embodiment, and examples thereof include benzene-based solvents (e.g., toluene, xylene, etc.), ketone-based solvents (e.g., cyclopentanone, methyl ethyl ketone (MEK), acetone, cyclohexanone, etc.), ester-based solvents (e.g., ethyl acetate, hexyl acetate, butyl acetate, carbitol acetate, etc.), and the like.

[0070] In addition to the above-mentioned components, the curable composition of the present embodiment may contain, as desired, other polymerizable compounds than the polymerizable compound (A) and the polymerizable compound (B), resin (polymer) crosslinking agents, curing catalysts, reducing agents, surfactants, chain transfer agents, photosensitizers, corrosion inhibitors, rust inhibitors, etc., within the scope of not impairing the effects of the present invention. The other polymerizable compounds than the polymerizable compound (A) and the polymerizable compound (B) are not particularly limited, but examples thereof include styrene, acrylonitrile, divinyl ether, diallyl ether, etc.

[0071] [Method for Producing Curable Composition] The method for producing the curable composition of this embodiment is not particularly limited. The curable composition can be obtained by adding the polymerizable compound (A) and the polymerizable compound (B), and, if necessary, a polymerization initiator, a filler (C), a polymerization initiator, a dispersant, and other additives to a stirring vessel and stirring and mixing them. A known stirrer or the like can be used for stirring and mixing. When other additives are added in the method for producing the curable composition, they only need to be stirred for a period of time sufficient to dissolve or disperse the additives. They may be added to the stirring vessel together with the polymerizable compound (A) and the polymerizable compound (B), or they may be added afterwards. As described above, the polymerizable compound (A) may be produced using the polymerizable compound (B) as a solvent, and the filler (C) and other components may be added to a mixture of the polymerizable compound (A) and the polymerizable compound (B). Furthermore, the curable composition of this embodiment has an excellent pot life and can be produced as a one-component composition, which provides excellent work efficiency and ease of handling.

[0072] The curable composition of the present embodiment may be a one-component composition or a two-component composition in which the polymerizable compound (A) and the polymerizable compound (B) are separate compositions. When the curable composition is a two-component type, the contents of the polymerizable compounds (A) and (B) can be adjusted by adjusting the compositions of each component so that the contents of each component fall within the above-mentioned ranges when the two components are mixed.

[0073] <<Cured Product>> The cured product of this embodiment can be obtained by curing the curable composition of this embodiment. The method for curing the curable composition is not particularly limited and can be appropriately selected from commonly used methods. Examples of the curing method include irradiation with active energy rays and heating. When the curable composition is cured by irradiation with active energy rays, the irradiation conditions are not particularly limited. For example, a high-pressure mercury lamp can be used in the atmosphere, with an integrated light dose of 1200 mJ / cm. 2The composition can be completely cured by heating. When the curable composition is cured by heating, the heating temperature is preferably 70 to 250°C, and more preferably 90 to 170°C. The heating time is preferably 90 minutes or less. When the curable composition of this embodiment is used as a two-component composition, it is preferable to mix the two components immediately before the curing operation. The other curing conditions can be appropriately selected from the conditions described above.

[0074] Furthermore, as described above, the curable composition of the cured product of this embodiment can exhibit excellent curability and pot life. Therefore, the cured product of this embodiment is advantageous in terms of productivity and energy efficiency during curing. Furthermore, it has excellent flexibility and a cured state, and even when formed into a composite material containing a filler, it can exhibit good heat resistance (low linear expansion coefficient) and moldability (crackless). Therefore, the cured product of this embodiment can be used in various applications, such as coating agents, sealing materials (underfills), resin films with carriers, prepregs, and resin parts of metal-clad laminates. The filler (C) can be used depending on the application of the cured product of this embodiment. Examples of applications for the filler (C) include sealing materials and heat dissipation materials.

[0075] From the viewpoint of heat resistance, the glass transition temperature (Tg) of the cured product of this embodiment is preferably 50 to 300°C, more preferably 100 to 250°C, and particularly preferably 120 to 200°C.

[0076] From the viewpoint of heat resistance, the linear expansion coefficient of the cured product of this embodiment at 80°C is preferably 40 ppm / °C or less, more preferably 30 ppm / °C or less, and particularly preferably 20 ppm / °C or less.

[0077] From the viewpoint of heat resistance, the linear expansion coefficient of the cured product of this embodiment at 140°C is preferably 45 ppm / °C or less, more preferably 35 ppm / °C or less, and particularly preferably 25 ppm / °C or less.

[0078] The flexural modulus of the cured product of this embodiment is preferably 8,000 to 14,000 MPa, more preferably 9,000 to 13,000 MPa, and particularly preferably 10,000 to 12,000 MPa, from the viewpoint of imparting impact resistance while maintaining a certain degree of flexibility to the cured product.

[0079] Unless otherwise specified, the above-mentioned ranges of values ​​can be obtained by the same methods as those described in the examples.

[0080] <<Curability Improver>> As described above, the polymerizable compound (B) can improve the curability of a curable composition using the polymerizable compound (A) alone. From this perspective, the compound represented by the above formula (II), which belongs to the polymerizable compound (B), can be used as a curability improver for other polymerizable compounds. The compound whose curability is to be improved is preferably the polymerizable compound (A), and more preferably the compound represented by formula (I).

[0081] The curability improver of this embodiment may be configured to contain one or more compounds represented by the following formula (II): Examples of a combination of two or more compounds represented by the following formula (II) include a combination of compounds in which o, p, q, and r of each compound are the same (however, o, p, q, and r within a single compound may be different) and the bonding sites of the condensed polycyclic hydrocarbon structure (tricyclo[5.2.1.0(2,6)]decane structure) and the maleimide group-containing group are different.

[0082] (In formula (II), o, p, q, and r each independently represent an integer of 1 to 3.)

[0083] The compound represented by formula (II) in the curability improver is preferably liquid at room temperature. In addition to the compound represented by formula (II), the curability improver may contain, as desired, a solvent, a surfactant, a corrosion inhibitor, a rust inhibitor, etc., within a range that does not impair the effects of the present invention.

[0084] Although the embodiment of the present invention has been described above, the present invention is not limited to the above description.

[0085] The present invention will be specifically described below using examples, but the present invention is not limited to the following examples.

[0086] [Production Example 1] (Synthesis of TCD-DMI) 72.4 g (0.43 mol) of 3-maleimidopropionic acid, 40.0 g (0.20 mol) of tricyclodecane dimethanol, 50 g of normal hexane, 250 g of toluene, 3.9 g of paratoluenesulfonic acid monohydrate (catalyst), and 0.01 g of 4-methoxyphenol (polymerization inhibitor) were charged into a reaction vessel equipped with a stirrer, thermometer, fractionating column, and condenser. Air was blown into this charged solution at a rate of 10 ml / min, and the reaction solution was heated to 90°C in an oil bath. A dehydration condensation reaction was carried out at atmospheric pressure for 15 hours, during which water produced by the reaction was removed. Next, the reaction solution was added to a separatory funnel, and the organic layer was washed with a 10% aqueous sodium hydroxide solution to remove unreacted 4-maleimidopropionic acid and the catalyst. The organic layer was then washed with water until the pH of the aqueous layer reached 7 or less. The organic layer was concentrated under reduced pressure at 60° C. to obtain the desired tricyclodecane dimethanol dimaleimide compound (TCD-DMI).

[0087] [Example 1-1 to Comparative Example 1-6] (Preparation of Polymerizable Compound) In a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser, the polymerizable compounds (A) and (B) (polymerizable compound (B′)) and a photopolymerization initiator in the amounts shown in Table 1 below were added under light shielding, and the mixture was stirred at room temperature (about 23° C.) to obtain polymerizable compositions for each of the Examples and Comparative Examples.

[0088] (Curability: Accumulated light amount at which tack-free film is obtained) The obtained polymerizable composition was applied to a film having a final thickness of 150 μm (size: 10 cm×10 cm), and exposed to light using a high-pressure mercury lamp under the following conditions. The minimum accumulated light amount (mJ / cm) at which tack-free film is obtained was 2 The tack-free state was determined by touching the surface of the cured film with a finger and determining whether or not a fingerprint was left on the surface. - Exposure conditions - N.V. (%): 100% Exposure lamp: High-pressure mercury lamp Illuminance: 480 mW / cm 2 Atmosphere: Under air Applicator Gap: 300 μm Finished film thickness: 150 μm

[0089] (Compatibility) The polymerizable compounds (A) and (B) were mixed in the ratio shown in Table 1 below and stirred at room temperature, and the compatibility of the polymerizable compounds (A) and (B) was evaluated according to the following criteria. - Criteria - A: No visible insoluble matter was observed. C: Visible insoluble matter was observed.

[0090] (Pot life) The obtained polymerizable composition was left at room temperature in the dark, and the pot life of the polymerizable composition was evaluated according to the following criteria. -Criteria- A: When left at room temperature, it did not gel even after 30 days. B: When left at room temperature, it did not gel even after 3 hours, but gelled before 30 days. C: When left at room temperature, it gelled within 3 hours.

[0091] (Transparency) The obtained polymerizable composition was applied to a film having a final thickness of 150 μm (size: 10 cm × 10 cm) and exposed to light under the above-mentioned conditions until the film became tack-free to obtain a sample. The obtained sample was visually observed, and the transparency was evaluated according to the following criteria. [Criteria] A: Colorless and transparent. B: Yellowish or brownish. C: Cloudy.

[0092] Light Acrylate DCP-A: manufactured by Kyoeisha Chemical Co., Ltd.; dimethyloltricyclodecane diacrylate (tricyclodecane dimethanol diacrylate); TCD-DMI: tricyclodecane dimethanol dimaleimide produced in Production Example 1; Viscoat #295: manufactured by Osaka Organic Chemical Industry Ltd.; trimethylolpropane triacrylate; Karenz MT (registered trademark) PE1: manufactured by Resonac Corporation; pentaerythritol tetrakis(3-mercaptobutyrate); Bismaleimidodiphenylmethane: manufactured by Tokyo Chemical Industry Co., Ltd.; 4,4'-bismaleimidodiphenylmethane; Bis(ethylmethylmaleimidophenyl)methane: manufactured by Tokyo Chemical Industry Co., Ltd.; bis(3-ethyl-5-methyl-4-maleimidophenyl)methane; IPBM: manufactured by Kawaguchi Chemical Industry Co., Ltd.; 1-maleimido-3-maleimidomethyl-3,5,5-trimethylcyclohexane TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (trade name: Irgacure TPO), manufactured by BASF

[0093] As shown in Table 1, the examples using the combined polymerizable compounds (A) and (B) exhibited good curability through photocuring under atmospheric conditions. In particular, comparing Example 1-1 with Comparative Example 1-1, the tack-free sensitivity was approximately four times higher, a favorable result. In Comparative Example 1-2, the polyfunctional acrylate TMP-3A was added to increase sensitivity, but the tack-free sensitivity was only improved by about two times compared to Comparative Example 1-1. In Comparative Example 1-3, a polyfunctional thiol was added, and the tack-free sensitivity was improved by four times compared to Comparative Example 1-1. However, the stability (pot life) of the polymerizable composition was poor, and gelation occurred within three hours. In Comparative Examples 1-4, 1-5, and 1-6, a general-purpose bismaleimide was used, but it was insoluble in DCP-A, and all results were inferior to those of the Examples.

[0094] Example 2-1 to Comparative Example 3-1 (Preparation of Polymerizable Compounds) Polymerizable compounds (A) and (B), a filler, a thermal polymerization initiator, and a silane coupling agent in the amounts shown in Table 2 below were placed in a stirring vessel, and the mixture was stirred for 60 seconds at atmospheric pressure at a revolution speed of 2,000 rpm using a planetary mixer (manufactured by Thinky Corporation, name: Awatori Rentaro ARV-310P) to obtain polymerizable compositions for each of the Examples and Comparative Examples.

[0095] The resulting polymerizable composition was then poured onto a 100 mm × 100 mm × 5 mm soda glass, a 2 mm thick silicon spacer was fixed to the periphery of the glass, and the composition was rolled so as to be sandwiched between another sheet of soda glass. The two sheets of soda glass were clamped together evenly at two points on each side with a double clip, and the composition was cured according to the curing conditions to obtain a sample with a finished film thickness of 2 mm (size: 5 cm × 5 cm).

[0096] (Linear expansion coefficient) A 2 mm thick cured product was cut to obtain a 5 mm x 5 mm x 2 mm test piece. Using a thermomechanical analyzer (TMA) (manufactured by NETZCH JAPAN, model: TMA 4000SA), the thermal expansion of the cured product was measured at a temperature increase rate of 5°C / min under a load of 5.0 g in a nitrogen atmosphere until the temperature of the cured product exceeded 200°C. The linear expansion coefficients (80°C, 140°C) were calculated from the thermal expansion of the obtained sample.

[0097] (Flexural Modulus) The cured product obtained with a thickness of 0.5 mm was machined to obtain a test piece of 50 mm × 10 mm × 0.5 mm. The test piece was measured for displacement and stress using a bending tester at a speed of 1 mm / min until it broke, and the flexural modulus of the sample was calculated from the obtained stress-strain curve.

[0098] (Cure state) The surface of the obtained sample was visually observed, and the cure state was evaluated according to the following criteria. [Criteria] A: No cracks were observed. B: Cracks were observed. C: Poorly cured (not completely uncured, with residual liquid components or softened areas at the edges of the cured product).

[0099] NK Ester DCP: manufactured by Shin-Nakamura Chemical Co., Ltd.; tricyclodecane dimethanol dimethacrylate Silica: manufactured by Denka Co., Ltd.; FB-3SDC (methacrl-modified product) Perbutyl O: manufactured by NOF Corporation; t-butyl-peroxy-2-ethylhexanate Perbutyl P: manufactured by NOF Corporation; α,α'-di(t-butylperoxy)diisopropylbenzene

[0100] As shown in Table 2, in the examples in which the polymerizable compounds (A) and (B) were used in combination, no cracks occurred on the surface of the cured product. In addition, it can be seen that the increase in the linear expansion coefficient was suppressed, and the heat resistance was excellent.

[0101] The disclosure of Japanese Patent Application No. 2024-030040, filed on February 29, 2024, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards mentioned in the specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A curable composition comprising: a polymerizable compound (A) having a condensed polycyclic hydrocarbon structure and two or more polymerizable functional groups bonded to the condensed polycyclic hydrocarbon structure; and a polymerizable compound (B) having a condensed polycyclic hydrocarbon structure and two or more maleimide groups bonded to the condensed polycyclic hydrocarbon structure, wherein the polymerizable compound (A) and the polymerizable compound (B) have the same condensed polycyclic hydrocarbon structure.

2. The curable composition according to claim 1, wherein the condensed polycyclic hydrocarbon structure of the polymerizable compound (A) and the condensed polycyclic hydrocarbon structure of the polymerizable compound (B) are aliphatic condensed polycyclic hydrocarbon structures.

3. The curable composition according to claim 1, wherein at least one of the two or more polymerizable functional groups possessed by the polymerizable compound (A) is a group having an ethylenically unsaturated double bond.

4. The curable composition according to claim 1, wherein the polymerizable compound (A) comprises a compound represented by the following formula (I): (In formula (I), R 1 , R 2 each independently represents H or CH3, and n and m each independently represents an integer of 1 to 3.

5. The curable composition according to claim 1, wherein the polymerizable compound (B) comprises a compound represented by the following formula (II): (In formula (II), o, p, q, and r each independently represent an integer of 1 to 3.) 6. The curable composition of claim 1, comprising a filler.

7. A curability enhancer comprising a compound represented by the following formula (II): (In formula (II), o, p, q, and r each independently represent an integer of 1 to 3.) 8. A cured product obtained by curing the curable composition according to any one of claims 1 to 6.

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