Curable composition and cured product thereof

Abstract

A curable composition containing naphthylmethyl (meth)acrylate and a (meth)acrylate having a 9,9-bisarylfluorene skeleton is prepared. The (meth)acrylate having the 9,9-bisarylfluorene skeleton may contain a (meth)acrylate represented by formula (1). (In the formula, R1 represents a substituent, m1 represents an integer of 0-8, Z1a and Z1b independently represent an arene ring, R2a and R2b independently represent a substituent, m2a and m2b independently represent an integer of 0 or more, A1a and A1b independently represent an alkylene group, n1a and n1b independently represent a number of 0 or more, and R3a and R3b independently represent a hydrogen atom or a methyl group.)　The curable composition has excellent balance between a high refractive index and a low viscosity, and also has excellent storage stability.

Description

Curable composition and cured product thereof

[0001] The present disclosure relates to a curable composition containing a (meth)acrylate compound having a 9,9-bisarylfluorene skeleton and naphthylmethyl (meth)acrylate, a cured product thereof, and a method for producing and use thereof.

[0002] (Meth)acrylate compounds having a fluorene skeleton [fluorene-based (meth)acrylates] not only exhibit heat resistance but also excellent optical properties such as a high refractive index, and are therefore effectively used as optical plastics (or optical resin materials) in various optical components. However, although fluorene-based (meth)acrylates have a high refractive index, they often lack sufficient handleability, and therefore attempts have been made to reduce the viscosity by adding a solvent or a reactive diluent, for example, by adding a reactive diluent, which is less likely to be limited in use as a curable composition compared to a solvent.

[0003] Japanese Patent Laid-Open Publication No. 2013-53310 (Patent Document 1) discloses a curable composition containing a curable component composed of a specific polyfunctional (meth)acrylate having a 9,9-bisphenylfluorene skeleton and phenoxybenzyl (meth)acrylate as a reactive diluent.

[0004] Furthermore, WO 2021 / 131942 (Patent Document 2) discloses a specific di(meth)acrylate having a fluorene skeleton [such as a 2,7-di(2-naphthyl)fluorene skeleton] in which aryl groups are bonded to the 1- to 8-positions, rather than the 9,9-positions.

[0005] JP 2013-53310 A International Publication No. 2021 / 131942

[0006] In general, the viscosity of a high refractive index (meth)acrylate can be reduced by adding a reactive diluent, but the refractive index tends to decrease with the addition, and there is a tendency for a trade-off between a high refractive index and a low viscosity. However, the curable composition described in Patent Document 1 is described as exhibiting a high refractive index and being able to improve handleability (reducing viscosity) without impairing curability. However, in recent years, there has been a demand for even higher refractive indices, and the curable composition described in Patent Document 1 is sometimes unable to fully meet this demand, leaving room for improvement in order to achieve both a high refractive index and a low viscosity at a higher level.

[0007] Furthermore, in the examples of Patent Document 2, it is described that 9,9-bis(3-hydroxypropyl)-2,7-di(2-naphthyl)fluorene is a solid that exhibits an extremely high refractive index, and that a curable composition containing this compound can achieve a good balance between a high refractive index and a low viscosity. However, Patent Document 2 does not describe anything about the storage stability of the curable composition.

[0008] Therefore, an object of the present disclosure is to provide a curable composition that has an excellent balance between a high refractive index and a low viscosity and also has excellent storage stability, a cured product thereof, a production method thereof, and uses thereof.

[0009] The present inventors aimed to achieve a better balance between a high refractive index and a low viscosity, and prepared a curable composition by combining a di(meth)acrylate having a diarylfluorene skeleton in which aryl groups are bonded to the 1- to 8-positions, as described in Patent Document 2, with a specific reactive diluent, as shown in the Reference Examples described below. However, they found that the composition had poor storage stability. Based on this discovery, the present inventors conducted further intensive research to achieve the above-mentioned object. As a result, they found that by combining a specific di(meth)acrylate having a 9,9-bisarylfluorene skeleton (in which aryl groups are bonded to the 9,9-positions instead of the 1- to 8-positions) with a specific reactive diluent, the resulting curable composition not only exhibits an excellent balance between a high refractive index and a low viscosity, but also exhibits good storage stability, thereby completing the present invention (or the present disclosure). That is, the present disclosure may include the following aspects, etc.

[0010] Aspect [1]: A curable composition comprising a (meth)acrylate having a 9,9-bisarylfluorene skeleton and naphthylmethyl (meth)acrylate.

[0011] Aspect [2]: The curable composition according to aspect [1], wherein the (meth)acrylate having a 9,9-bisarylfluorene skeleton includes a (meth)acrylate represented by the following formula (1):

[0012]

[0013] (In the formula, R １ represents a substituent, m1 represents an integer of 0 to 8, Z １ａ and Z １ｂ each independently represents an arene ring; R ２ａ and R ２ｂ each independently represents a substituent, m2a and m2b each independently represents an integer of 0 or more, １ａ and A １ｂ each independently represents an alkylene group, n1a and n1b each independently represents a number of 0 or more, R ３ａ and R ３ｂ are independently a hydrogen atom or a methyl group.

[0014] Aspect [3]: In the formula (1), R １ represents a halogen atom, a hydrocarbon group, an alkoxy group, an acyl group, a nitro group, a cyano group or a substituted amino group; m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ is independently C ６－１８ Arene rings (e.g., C ６－１４ arene ring, preferably C ６－１２ arene ring), R ２ａ and R ２ｂ each independently represents a halogen atom, a hydrocarbon group, an alkoxy group, an acyl group, a nitro group, a cyano group, or a substituted amino group; m2a and m2b each independently represent an integer of 0 to 2; A １ａ and A １ｂ is independently C ２－４ The curable composition according to embodiment [2], wherein n1a and n1b each independently represent an alkylene group and an integer of 0 to 10.

[0015] Aspect [4]: ​​In the formula (1), R １ represents a hydrocarbon group, m1 represents an integer of 0 to 2, Z １ａ and Z １ｂ is independently C ６－１２ Arene rings (e.g., C ６－１０ arene ring), R ２ａ and R ２ｂ each independently represents a hydrocarbon group, m2a and m2b each independently represents an integer of 0 to 2, １ａ and A １ｂ is independently C ２－３ The curable composition according to aspect [2] or [3], wherein n1a and n1b each independently represent an integer of 0 to 8.

[0016] Aspect [5]: The curable composition according to any one of Aspects [1] to [4], wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton to the naphthylmethyl (meth)acrylate is the former / the latter (mass ratio) = 20 / 80 to 85 / 15.

[0017] Aspect [6]: The curable composition according to any one of Aspects [1] to [5], wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton to the naphthylmethyl (meth)acrylate is the former / the latter (mass ratio) = 40 / 60 to 80 / 20.

[0018] Aspect [7]: A cured product obtained by curing the curable composition according to any one of aspects [1] to [6].

[0019] Aspect [8]: A method for producing a cured product, comprising a step of curing the curable composition according to any one of aspects [1] to [6].

[0020] Aspect [9]: An optical component comprising the cured product according to aspect [7].

[0021] In addition, the present disclosure may achieve the following secondary objectives (solve secondary problems).

[0022] That is, another object of the present disclosure is to provide a curable composition having an excellent balance between a high refractive index and a low viscosity, excellent storage stability, and excellent curability, a cured product thereof, a production method thereof, and uses thereof.

[0023] Still another object of the present disclosure is to provide a curable composition having an excellent balance between a high refractive index and a low viscosity, excellent storage stability, and excellent heat resistance (or resistance to thermal decomposition), a cured product thereof, and a production method and use thereof.

[0024] Another object of the present disclosure is to provide a curable composition and a cured product thereof that have an excellent balance between a high refractive index and a low viscosity, and also have excellent storage stability, and that have excellent flexibility (or toughness, particularly bending durability) even though they have a rigid chemical structure such as an aromatic ring skeleton, as well as a production method and uses thereof.

[0025] In this specification and claims, the number of carbon atoms in a substituent is represented by C １ , C ６ , C １０ For example, an alkyl group with one carbon atom is represented by "C １ alkyl group” and aryl groups with 6 to 10 carbon atoms are “C ６－１０ An aryl group is indicated as such.

[0026] In this specification and claims, the term "independently" means that a plurality of components are independent components, for example, Z １ａ and Z １ｂ In this case, the arene rings may be the same or different from each other.

[0027] Furthermore, in this specification and claims, a numerical range indicated as "X to Y" may include the numerical values ​​X and Y.

[0028] According to the present disclosure, it is possible to provide a curable composition that has an excellent balance between a high refractive index and a low viscosity and also has excellent storage stability, a cured product thereof, a production method thereof, and uses thereof.

[0029] FIG. 1 is a schematic diagram illustrating a method for bending a cured film in a bending durability test.

[0030] The curable composition of the present disclosure contains at least (A) a (meth)acrylate having a 9,9-bisarylfluorene skeleton and (B) naphthylmethyl (meth)acrylate.

[0031] [(A) (Meth)acrylate Having a 9,9-Bisarylfluorene Skeleton] Examples of the 9,9-bisarylfluorene skeleton in the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton include 9,9-bis(C) arylfluorene skeletons such as a 9,9-bisphenylfluorene skeleton, a 9,9-bisbiphenylylfluorene skeleton, and a 9,9-bisnaphthylfluorene skeleton. ６－１８ aryl)fluorene skeleton [e.g., 9,9-bis(C ６－１４ aryl)fluorene skeleton, etc., and preferably 9,9-bis(C ６－１０ 9,9-bis(C aryl)fluorene skeleton ６－１２ aryl)fluorene skeleton, etc.], and more preferably a 9,9-bisphenylfluorene skeleton or a 9,9-bisbiphenylylfluorene skeleton.

[0032] The (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton preferably contains a (meth)acrylate compound represented by the following formula (F) (also simply referred to as compound (F)).

[0033]

[0034] (In the formula, R １ represents a substituent, m1 represents an integer of 0 to 8, Z １ａ and Z １ｂ each independently represents an arene ring; R ２ａ and R ２ｂ each independently represents a substituent, m2a and m2b each independently represents an integer of 0 or more, １ａ and A １ｂ each independently represents an alkylene group, n1a and n1b each independently represents a number of 0 or more (for example, an integer), and X １ａ and X １ｂ each independently represents a hydrogen atom or a (meth)acryloyl group; X １ａ and X １ｂAt least one of these represents a (meth)acryloyl group.

[0035] In the formula (F), R １ The substituent represented by R may be a non-reactive group or a non-polymerizable group. １ Examples of the group include a halogen atom, a hydrocarbon group (or a group [—R ｈ ]), a group [—OR ｈ ] (wherein, R ｈ represents a hydrocarbon group), a group [—SR ｈ ] (wherein, R ｈ represents a hydrocarbon group), an acyl group, a nitro group, a cyano group, a substituted amino group (mono- or di-substituted amino group), and the like.

[0036] In this specification and claims, R ｈ The hydrocarbon groups represented by the following formula (I) each represent an independent hydrocarbon group, and may be the same or different from each other.

[0037] Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0038] A hydrocarbon group (or group [—R ｈ ]) may be a saturated or unsaturated hydrocarbon group, an aliphatic (including alicyclic) or aromatic hydrocarbon group, and may be a chain (straight or branched) or cyclic hydrocarbon group, or a hydrocarbon group having a structure in which a chain and a cyclic structure are combined. ｈ Examples of the alkyl group include an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group.

[0039] Examples of the alkyl group (linear or branched alkyl group) include C alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, and t-butyl group. １－１０ alkyl group, preferably C １－６ alkyl group, more preferably C １－４ It is an alkyl group.

[0040] Examples of the cycloalkyl group include a C cyclopentyl group, a cyclohexyl group, and the like. ５－１０Cycloalkyl groups are exemplified.

[0041] Examples of the aryl group include a C aryl group such as a phenyl group, an alkylphenyl group, a biphenylyl group, and a naphthyl group. ６－１２ Examples of the alkylphenyl group include mono- to tri-C alkylphenyl groups such as methylphenyl group (or tolyl group) and dimethylphenyl group (or xylyl group). １－４ Examples include alkyl-phenyl groups.

[0042] Examples of the aralkyl group include C aryl groups such as benzyl and phenethyl groups. ６－１０ Aryl-C １－４ Examples of suitable alkyl groups include:

[0043] The group [-OR ｈ ] and [-SR ｈ ], in which R ｈ The hydrocarbon group represented by R １ Examples of the hydrocarbon groups include the same hydrocarbon groups as those exemplified above, including preferred embodiments thereof, such as alkyl groups, cycloalkyl groups, aryl groups, and aralkyl groups.

[0044] The group [-OR ｈ ] is, for example, the hydrocarbon group R ｈ Examples of the alkoxy group (linear or branched alkoxy group) include C groups such as methoxy group, ethoxy group, propoxy group, n-butoxy group, isobutoxy group, and t-butoxy group. １－１０ Examples of the cycloalkyloxy group include a C alkoxy group such as a cyclohexyloxy group. ５－１０ Examples of the aryloxy group include a C aryloxy group such as a phenoxy group. ６－１０ Examples of the aralkyloxy group include a C aryloxy group such as a benzyloxy group. ６－１０ Aryl-C １－４ An example is an alkyloxy group.

[0045] The group [—SRｈ ] is, for example, the hydrocarbon group R ｈ Examples of the alkylthio group include a C alkylthio group, a cycloalkylthio group, an arylthio group, an aralkylthio group, etc. Examples of the alkylthio group include a C alkylthio group, such as a methylthio group, an ethylthio group, a propylthio group, an n-butylthio group, and a t-butylthio group. １－１０ Examples of the cycloalkylthio group include a C alkylthio group such as a cyclohexylthio group. ５－１０ Examples of the arylthio group include a C thiophenoxy group and the like. ６－１０ Examples of the aralkylthio group include a C arylthio group such as a benzylthio group. ６－１０ Aryl-C １－４ Examples include alkylthio groups.

[0046] Examples of the acyl group include C groups such as an acetyl group. １－６ Examples include an alkyl-carbonyl group.

[0047] Examples of the mono- or di-substituted amino group include a dialkylamino group and a bis(alkylcarbonyl)amino group. Examples of the dialkylamino group include a di-C group such as a dimethylamino group. １－４ Examples of the bis(alkylcarbonyl)amino group include a bis(C １－４ alkyl-carbonyl)amino groups.

[0048] These R １ Representative examples of R include a halogen atom, a hydrocarbon group, an alkoxy group, an acyl group, a nitro group, a cyano group, and a substituted amino group. １ is a halogen atom, a hydrocarbon group, or a cyano group, and more preferably a hydrocarbon group such as an alkyl group or an aryl group. Examples of the alkyl group (linear or branched alkyl group) include C 1, C 2, C 3, C 4, C 5, C 6, C 7, C 8, C 9, C 10, C 11, C 12, C 13, C 14, C 15, C 16, C 17, C 18, C 19, C 20, C 21, C 22, C 23, C 24, C 25, C 36, C 26, C 37, C 27, C 38, C 28, C 39, C 40, C 29, C 39, C 41, C 25, C 38, C 26, C 27, C 28, C 39, C 29, C １－６ alkyl groups, and C groups such as methyl groups. １－４An alkyl group is preferred. From the viewpoint of easily improving the refractive index, an aryl group is preferred, and a C ６－１２ Aryl groups (e.g., C groups such as phenyl and naphthyl groups) ６－１０ aryl groups, etc.).

[0049] R １ The number of substitutions m1 is, for example, an integer of about 0 to 6, preferably an integer of 0 to 4, an integer of 0 to 2, more preferably 0 or 1 or 0 or 2, and particularly preferably 0 or 2. When m1 is 2 or more, 2 or more R １ The types of may be the same or different. In addition, when both of the two benzene rings forming the fluorene skeleton have R １ When R is substituted, R １ and the type of R of the other benzene ring １ The types of R may be the same or different, and are preferably the same. １ The substitution positions of are not particularly limited as long as they are the 1- to 8-positions of the fluorene skeleton, and may be, for example, the 2-position, 3-position, or 2,7-position, with the 2,7-positions being preferred.

[0050] Z １ａ or Z １ｂ Examples of the arene ring (aromatic hydrocarbon ring) represented by the formula (I) include a monocyclic arene ring such as a benzene ring, a polycyclic arene ring, etc. Examples of the polycyclic arene ring include a fused polycyclic arene ring (fused polycyclic aromatic hydrocarbon ring) and a ring-assembled arene ring (ring-assembled aromatic hydrocarbon ring).

[0051] The fused polycyclic arene ring includes, for example, fused bicyclic arene rings, fused tricyclic arene rings, and other fused bicyclic to tetracyclic arene rings. The fused bicyclic arene ring includes, for example, fused bicyclic C rings such as naphthalene ring and indene ring. １０－１６ Examples of the fused tricyclic arene ring include fused tricyclic C arenes such as an anthracene ring and a phenanthrene ring. １４－２０ Preferred fused polycyclic arene rings include fused polycyclic C arene rings such as naphthalene rings. １０－１４It is an arene ring.

[0052] Examples of the ring-assembled arene ring include biarene rings such as biphenyl ring, phenylnaphthalene ring, and binaphthyl ring; and terarene rings such as terphenyl ring. Preferred ring-assembled arene rings include C １２－１８ It is a biarene ring.

[0053] In this specification and claims, the term "ring-assembly arene ring" refers to two or more ring systems (arene ring systems) directly linked by single bonds or double bonds, and the number of bonds directly linking the rings is one less than the number of ring systems. For example, as described above, phenylnaphthalene rings and binaphthyl rings are classified as ring-assembly arene rings even though they have a fused polycyclic arene ring skeleton, and are clearly distinguished from "fused polycyclic arene rings" such as naphthalene rings (non-ring-assembly arene rings).

[0054] Preferred Z １ａ and Z １ｂ is C ６－１４ C such as arene ring ６－１８ arene rings, and more preferably C rings such as benzene rings, naphthalene rings, and biphenyl rings. ６－１２ arene rings, and more preferably C rings such as benzene rings and naphthalene rings. ６－１０ It may be an arene ring, and a benzene ring is particularly preferred in terms of excellent storage stability, and a C ring such as a biphenyl ring is preferred in terms of facilitating improvement of the refractive index. １０－１２ An arene ring is preferred. １ａ and Z １ｂ The types may be the same or different from each other, but are preferably the same.

[0055] In addition, Z bonded to the 9-position of the fluorene ring １ａ and Z １ｂ The substitution position (bonding position) in １ａ , Z １ｂ When Z is a benzene ring, it may be at any position. １ａ , Z １ｂ is a naphthalene ring, it is either the 1-position (1-naphthyl) or the 2-position (2-naphthyl), preferably the 2-position; Z１ａ , Z １ｂ When is a biphenyl ring, it is at the 2-position, 3-position or 4-position, preferably the 3-position.

[0056] R ２ａ or R ２ｂ The substituent represented by R may be a non-reactive group or a non-polymerizable group. ２ａ , R ２ｂ Examples of the R １ The examples of the groups exemplified as R include the same groups as those exemplified as R, including preferred embodiments thereof. ２ａ , R ２ｂ Examples of the alkyl group include a halogen atom, a hydrocarbon group, an alkoxy group, an acyl group, a nitro group, a cyano group, and a substituted amino group. Preferred examples include hydrocarbon groups such as an alkyl group (a linear or branched alkyl group), a cycloalkyl group, an aryl group, and an aralkyl group, and groups such as an alkoxy group (a linear or branched alkoxy group) [—OR ｈ and more preferably C such as a methyl group. １－６ C such as alkyl group and cyclohexyl group ５－８ C such as cycloalkyl group, phenyl group ６－１４ C such as aryl group, benzyl group ６－１２ Aryl-C １－６ C such as alkyl group, methoxy group １－４ Among them, alkyl groups, aryl groups (C groups such as phenyl groups) ６－１０ aryl groups, aralkyl groups, and other hydrocarbon groups (e.g., C １－１２ Hydrocarbon groups) are preferred, and alkyl groups (C such as methyl groups) are particularly preferred. １－４ An aralkyl group (such as a C alkyl group) is preferred, and an aralkyl group (such as a C benzyl group) is particularly preferred. ６－１０ Aryl-C １－４ alkyl group) is preferred. ２ａ and R ２ｂ The types of R may be the same or different. ２ａ is an aryl group, R ２ａ is Z １ａ may form a ring assembly arene ring together with R ２ｂ is an aryl group, R２ｂ is Z １ｂ may form a ring assembly arene ring together with

[0057] R ２ａ or R ２ｂ The number of substitutions m2a or m2b is Z １ａ or Z １ｂ can be selected appropriately depending on the type of R, and may be, for example, an integer of about 0 to 6, preferably an integer of 0 to 4, more preferably an integer of 0 to 2, even more preferably 0 or 1, and particularly preferably 0. m2a and m2b may be different from each other, but are preferably the same. When m2a is 2 or more, two or more R ２ａ may be the same or different from each other; when m2b is 2 or more, two or more R ２ｂ The types may be the same or different from each other.

[0058] R ２ａ and R ２ｂ The substitution position of Z is not particularly limited. １ａ and Z １ｂ In the formula (I), the 9-position of the fluorene ring and the group [—O—(A １ａ O) ｎ１ａ -X １ａ ] and [—O—(A １ｂ O) ｎ１ｂ -X １ｂ ](simply, X １ It is sufficient that the substituent is at a position other than the bonding position with the substituted group (also referred to as a "containing group"). １ａ and Z １ｂ The X in １ Ortho position (X １ The carbon atom adjacent to the bonding position of the containing group may be substituted.

[0059] A １ａ or A １ｂ Examples of the alkylene group (linear or branched alkylene group) represented by the formula (I) include C alkylene groups such as an ethylene group, a propylene group (1,2-propanediyl group), a trimethylene group, a 1,2-butanediyl group, and a tetramethylene group. ２－６ alkylene groups, and preferably C ２－４C alkylene group, more preferably ethylene group, propylene group, etc. ２－３ An alkylene group, particularly an ethylene group, is preferred. １ａ and A １ｂ The types may be the same or different from each other, but are preferably the same.

[0060] Alkyleneoxy group [-(A １ａ O)-] or [-(A １ｂ The number of repetitions (number of added moles) n1a or n1b of the formula

[00100] - may be selected from the range of about 0 to 20, for example, and may be preferably selected in the following stepwise manner: 0 to 15, 0 to 10, 0 to 8, 0 to 7, or 0 to 6; depending on the application, for example, when a high refractive index is particularly important, the number of repetitions is more preferably selected in the following stepwise manner: 0 to 10, 0 to 6, 0 to 3, 0 to 2, or 0 to 1.5 (e.g., 0.5 to 1.5), and even more preferably 0 to 1 (e.g., 1); and when low viscosity and / or flexibility (toughness or bending durability) are particularly important, the number of repetitions is more preferably selected in the following stepwise manner: 0 to 15, 1 to 10, 3 to 8, 4 to 7, or 4.5 to 6.5, and even more preferably 5 to 6. In this specification and claims, the "number of repetitions (number of added moles)" may be an integer, an average value (arithmetic mean value, additive mean value), or an average number of added moles. Therefore, n1a and n1b may be an integer (for example, an integer within the range described above) or an average value (average number of moles added).

[0061] The total number of repeating numbers n1a and n1b, that is, the total number of alkyleneoxy groups [-(A １ａ O)-] and [-(A １ｂ In the present disclosure, the total number (or total number of added moles) of n1a (O)-] may be simply referred to as n1a + n1b, and in formula (F) [or formula (1) described below], n1a + n1b may be specified instead of n1a and n1b.

[0062] n1a+n1b may be selected, for example, from a range of about 0 to 40, preferably in the following stepwise manner: 0 to 30, 0 to 20, 0 to 16, 0 to 14, 0 to 12; depending on the application, for example, when a high refractive index is particularly important, more preferably in the following stepwise manner: 0 to 20, 0 to 12, 0 to 6, 0 to 4, 0 to 3 (e.g., 1 to 3), and even more preferably 0 to 2 (e.g., 2); when low viscosity and / or flexibility (toughness or bending durability) are particularly important, more preferably in the following stepwise manner: 0 to 30, 2 to 20, 5 to 17, 6 to 16, 8 to 14, 9 to 13, and even more preferably 10 to 12. Furthermore, n1a+n1b may be an integer (e.g., an integer within the range described above) or an average value (average number of moles added). Note that n1a+n1b may be measured according to the method described in JP-A-2013-053310.

[0063] When n1a, n1b and / or n1a+n1b are within an appropriate range that is not too large, a decrease in the refractive index tends to be easily suppressed, and when they are within an appropriate range that is not too small, an increase in viscosity (deterioration in handling or ease of handling) and a decrease in flexibility (toughness or bending durability) tend to be easily suppressed.

[0064] In addition, n1a and n1b may be the same or different. When n1a is 2 or more, two or more alkyleneoxy groups [-(A １ａ When n1b is 2 or more, the number of alkyleneoxy groups [-(A １ｂ The types of the groups may be different from each other, but are preferably the same.

[0065] The group [—O—(A １ａ O) ｎ１ａ -X １ａ ] and [—O—(A １ｂ O) ｎ１ｂ -X １ｂ ] (i.e., X １ Ring Z of the １ａ and Z １ｂ The substitution position for Z is not particularly limited. １ａ and Z １ｂIt is sufficient to substitute at the appropriate positions of X. １ Ring Z of the containing group １ａ and Z １ｂ The substitution position for Z １ａ and / or Z １ｂ When Z is a benzene ring, it is preferably substituted at any one of the 2-, 3-, and 4-positions, among which the 3- or 4-position, and particularly the 4-position, of the phenyl group bonded to the 9-position of the fluorene ring. １ａ and / or Z １ｂ When Z is a naphthalene ring, it is often substituted at any one of the 5- to 8-positions of the naphthyl group bonded to the 9-position of the fluorene ring. For example, the 1- or 2-position of the naphthalene ring is substituted with the 9-position of the fluorene ring (substitution in a 1-naphthyl or 2-naphthyl relationship), and it is preferred that Z be substituted with the 1,5- or 2,6-positions, particularly 2,6-positions, relative to this substitution position. １ａ and / or Z １ｂ is a ring-assembled arene ring, X １ The substitution position of the containing group is not particularly limited, and for example, it may be substituted on the arene ring bonded to the 9-position of the fluorene or on the arene ring adjacent to this arene ring. １ａ and / or Z １ｂ is a biphenyl ring (or Z １ａ and / or Z １ｂ is a benzene ring, m2a and / or m2b is 1, R ２ａ and / or R ２ｂ is a phenyl group), it is preferred that the 3-position of the biphenyl ring is bonded to the 9-position of the fluorene, and the 6-position of the biphenyl ring is bonded to X １ It is preferred to bond to the containing group.

[0066] X １ａ and X １ｂ may be either a hydrogen atom or a (meth)acryloyl group, but at least one of them is a (meth)acryloyl group, and preferably both are (meth)acryloyl groups. Therefore, the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton is １ａ and X １ｂand (2) are (meth)acryloyl groups, that is, a (meth)acrylate represented by the following formula (1) (also simply referred to as compound (1)).

[0067]

[0068] (In the formula, R １ , m1, Z １ａ , Z １ｂ , R ２ａ , R ２ｂ , m2a, m2b, A １ａ , A １ｂ , n1a and n1b are the same as those in formula (F) including preferred embodiments thereof, and R ３ａ and R ３ｂ are independently a hydrogen atom or a methyl group.

[0069] In the formula (1), R ３ａ , R ３ｂ R may be either a hydrogen atom or a methyl group, but is preferably a hydrogen atom in terms of ease of improving reactivity (or curability) and refractive index. ３ａ and R ３ｂ The types may be the same or different from each other, and are preferably the same.

[0070] Representative compounds (F) [or compounds (1)] include those represented by the formula (F) [or the formula (1)], where R １ represents a halogen atom, a hydrocarbon group, an alkoxy group, an acyl group, a nitro group, a cyano group or a substituted amino group; m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ is independently C ６－１８ C arene ring (preferably a benzene ring, a naphthalene ring, a biphenyl ring, etc.) ６－１２ arene ring), R ２ａ and R ２ｂ each independently represents a halogen atom, a hydrocarbon group, an alkoxy group, an acyl group, a nitro group, a cyano group, or a substituted amino group; m2a and m2b each independently represent an integer of 0 to 2; A １ａ and A １ｂ is independently C ２－４an alkylene group, and n1a and n1b independently represent a number of 0 to 10, or n1a + n1b represents a number of 0 to 20;

[0071] Preferably, in the formula (F) [or the formula (1)], R １ is a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group (e.g., C １－１０ m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ is independently C ６－１２ C arene rings (e.g., benzene rings, naphthalene rings, etc.) ６－１０ arene ring), R ２ａ and R ２ｂ are independently a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group (e.g., C １－１０ m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ is independently C ２－３ (meth)acrylate compounds in which n1a and n1b independently represent an alkylene group, and n1a and n1b represent a number of 0 to 8 (particularly, 0 to 3 or 3 to 8), or n1a + n1b represent a number of 0 to 16 (particularly, 0 to 6 or 6 to 16);

[0072] More preferably, in the formula (F) [or the formula (1)], R １ is C １－６ alkyl groups such as alkyl groups (especially C groups such as methyl groups) １－４ alkyl group), C ６－１２ an aryl group such as an aryl group or C ６－１０ Aryl-C １－４ Aralkyl groups such as alkyl groups, in particular aryl groups, among which C groups such as phenyl and naphthyl groups ６－１０ represents an aryl group, m1 represents an integer of 0 to 2, Z １ａ and Z １ｂ are independently C groups such as benzene ring and naphthalene ring. ６－１０ is an arene ring (particularly a benzene ring), or represents a benzene ring or a biphenyl ring; R ２ａ and R２ｂ is independently C １－６ alkyl groups such as alkyl groups (especially C groups such as methyl groups) １－４ alkyl group), C ６－１２ aryl groups such as aryl groups (particularly phenyl groups) or C ６－１２ Aryl-C １－６ Aralkyl groups such as alkyl groups, among which alkyl groups or aralkyl groups, particularly aralkyl groups (especially C groups such as benzyl groups) ６－１０ Aryl-C １－４ m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ are independently C groups such as ethylene groups and propylene groups. ２－３ represents an alkylene group (particularly, an ethylene group), and n1a and n1b independently represent a number of 0 to 7 (particularly, 0 to 2 or 4 to 7), or n1a + n1b represent a number of 0 to 14 (particularly, 0 to 4 or 8 to 14).

[0073] Specific examples of compound (F) [or compound (1)] include mono- or di(meth)acrylates [particularly di(meth)acrylates] of 9,9-bis(hydroxyaryl)fluorene or its alkylene oxide (or corresponding alkylene carbonate or haloalkanol) adduct.

[0074] Examples of the 9,9-bis(hydroxyaryl)fluorene include 9,9-bis(hydroxyphenyl)fluorene, 9,9-bis(alkyl-hydroxyphenyl)fluorene, 9,9-bis(aryl-hydroxyphenyl)fluorene, 9,9-bis(hydroxynaphthyl)fluorene, and 9,9-bis[(aryl-aralkyl-hydroxy)phenyl]fluorene.

[0075] Examples of 9,9-bis(hydroxyphenyl)fluorene include 9,9-bis(4-hydroxyphenyl)fluorene.

[0076] Examples of the 9,9-bis(alkyl-hydroxyphenyl)fluorene include 9,9-bis[(mono- or di-)C]fluorene such as 9,9-bis(4-hydroxy-3-methylphenyl)fluorene and 9,9-bis(4-hydroxy-3,5-dimethylphenyl)fluorene. １－４ alkyl-hydroxyphenyl]fluorene and the like.

[0077] Examples of 9,9-bis(aryl-hydroxyphenyl)fluorene include 9,9-bis(C ６－１０ aryl-hydroxyphenyl)fluorene and the like.

[0078] Examples of 9,9-bis(hydroxynaphthyl)fluorene include 9,9-bis(6-hydroxy-2-naphthyl)fluorene and 9,9-bis(5-hydroxy-1-naphthyl)fluorene.

[0079] Examples of 9,9-bis[(aryl-aralkyl-hydroxy)phenyl]fluorene include 9,9-bis[(C ６－１０ Aryl-C ６－１０ Aryl C １－４ 9,9-bis[(C alkyl-hydroxy)phenyl]fluorene, such as 9,9-bis[(3-benzyl-4-hydroxy-5-phenyl)phenyl]-2,7-di(2-naphthyl)fluorene; ６－１０ Aryl-C ６－１０ Aryl C １－４ alkyl-hydroxy)phenyl]-di(C ６－１０ aryl)fluorene and the like.

[0080] Representative alkylene oxides (or corresponding alkylene carbonates or haloalkanols) that may be added to the 9,9-bis(hydroxyaryl)fluorene include C alkylene oxides such as ethylene oxide and propylene oxide. ２－３ Alkylene oxide (C ２－３ Alkylene carbonate or C ２－３The number of moles added (or the average number of moles added) of the alkylene oxide (alkylene carbonate or haloalkanol) corresponds to the description of n1a+n1b above, and is the same including preferred embodiments.

[0081] More specific examples of compound (F) [or compound (1)], when a high refractive index is particularly important, include 9,9-bis[(meth)acryloyloxyphenyl]fluorenes such as 9,9-bis[4-(meth)acryloyloxyphenyl]fluorene, 9,9-bis[(meth)acryloyloxyalkoxyphenyl]fluorene, 9,9-bis[(aryl-aralkyl-(meth)acryloyloxy)phenyl]fluorene or 9,9-bis[(aryl-aralkyl-(meth)acryloyloxyalkoxy)phenyl]fluorene, preferably 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene, 9,9-bis[4-(2-(meth)acryloyloxypropoxy)phenyl]fluorene, and the like. ２－４ 9,9-bis[(C alkoxy-phenyl)]fluorene, or 9,9-bis[(3-benzyl-4-(2-(meth)acryloyloxyethoxy)-5-phenyl)phenyl]-2,7-di(2-naphthyl)fluorene; ６－１０ Aryl-C ６－１０ Aryl C １－４ Alkyl-(meth)acryloyloxy C ２－４ alkoxy)phenyl]-di(C ６－１０ When low viscosity and / or flexibility (toughness or flexural durability) are particularly important, 9,9-bis[(meth)acryloyloxypolyalkoxyphenyl]fluorene, preferably 9,9-bis[(meth)acryloyloxypolyC such as 9,9-bis[4-((meth)acryloyloxy-tetra- or heptaethoxyphenyl]fluorene, may be used. ２－４ and alkoxy-phenyl]fluorene.

[0082] The (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton may contain the compound (F) [or the compound (1)] either alone or in combination of two or more kinds.

[0083] The proportion of the compound (F) [or compound (1)] relative to the total amount of the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton is, for example, about 30 to 100% by mass, preferably 50% by mass or more, 70% by mass or more, 90% by mass or more in the following stepwise manner, and more preferably substantially 100% by mass.

[0084] The compound (F) is X １ａ and X １ｂ and X may contain at least a compound (1) [di(meth)acrylate] in which both of １ａ , X １ｂ The compound (1) may contain a compound (1) [mono(meth)acrylate] in which one of the groups is a hydrogen atom and the other is a (meth)acryloyl group, or may be a mixture containing both the compound (1) [di(meth)acrylate] and the mono(meth)acrylate. The mono(meth)acrylate may be a by-product generated during the synthesis of the compound (1) [di(meth)acrylate]. The by-product mono(meth)acrylate may be removed or isolated from the corresponding compound (1) [di(meth)acrylate], but complete removal is often difficult (complicated or impractical) from the standpoint of productivity, etc., and therefore the by-product mono(meth)acrylate may be included together with the compound (1) [di(meth)acrylate] without being completely removed by purification.

[0085] Therefore, in compound (F), it is preferable that compound (1) [di(meth)acrylate] is the main component, and the proportion of the mono(meth)acrylate may be, for example, about 30% or less (e.g., 0 to 20%), preferably 15% or less (e.g., 1 to 12%), more preferably 10% or less (e.g., 2 to 8%), and particularly about 5% or less, based on the total amount of compound (1) [di(meth)acrylate] and the mono(meth)acrylate, as an area percentage in high performance (or high speed) liquid chromatography (HPLC). In this specification and claims, the area percentage can be calculated by measuring compound (F) [or compound (1)] using HPLC under the following conditions: mobile phase: acetonitrile / distilled water (volume ratio) = 90 / 10, flow rate: 0.5 mL / min, and detection wavelength: 254 nm.

[0086] [(B) Naphthylmethyl (meth)acrylate] The naphthylmethyl (meth)acrylate (B) may function as a reactive diluent. When the naphthylmethyl (meth)acrylate (B) is combined with a (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton, rather than a (meth)acrylate having aryl groups only at the 1- to 8-positions of the fluorene skeleton, it appears that the naphthylmethyl (meth)acrylate (B) has a high refractive index and low viscosity in a well-balanced manner, and also has surprisingly excellent storage stability.

[0087] As the naphthylmethyl (meth)acrylate (B), 1-naphthylmethyl (meth)acrylate is preferred, and 1-naphthylmethyl acrylate is more preferred.

[0088] The mass ratio (A / B) of the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton to the naphthylmethyl (meth)acrylate (B) may be, for example, the former / latter (mass ratio) = about 10 / 90 to 90 / 10, and is preferably 20 / 80 to 85 / 15, 30 / 70 to 82 / 18, 40 / 60 to 80 / 20, or 45 / 55 to 75 / 25, and more preferably 35 / 65 to 65 / 35, 40 / 60 to 60 / 40, or 45 / 55 to 55 / 45. Furthermore, in cases where the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton contains the compound (F) [or the compound (1)] having a large value of n1a+n1b, from the viewpoint of further improving flexibility (particularly, bending durability), the mass ratio (A / B) may be, for example, about 53 / 47 to 90 / 10, and preferably is, in the following stepwise order, 55 / 45 to 85 / 15, 60 / 40 to 80 / 20, and 65 / 35 to 75 / 25. Furthermore, in cases where the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton also has aryl groups (such as naphthyl groups) at the 1- to 8-positions, or where a polycyclic arene ring (such as a biphenyl ring) is bonded to the 9,9-positions, or where the arene ring bonded to the 9,9-positions has an aralkyl group (such as a benzyl group), the mass ratio (A / B) may be, for example, about 10 / 90 to 50 / 50, and preferably is, in the following stepwise order, 15 / 85 to 45 / 55, 20 / 80 to 40 / 60, or 25 / 75 to 35 / 65. When the proportion of the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton is in an appropriate range that is not too small, there is a tendency that a decrease in refractive index, a decrease in curability, and a decrease in bending durability are easily suppressed. When the proportion of the naphthylmethyl (meth)acrylate (B) is in an appropriate range that is not too small, there is a tendency that a decrease in viscosity is easily suppressed without a significant decrease in refractive index, and a decrease in storage stability is easily suppressed.

[0089] The total proportion of the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton and the naphthylmethyl (meth)acrylate (B) relative to all polymerizable components in the curable composition is, for example, about 30 to 100% by mass, preferably 50% by mass or more, 70% by mass or more, 90% by mass or more in the following stepwise manner, and more preferably substantially 100% by mass.

[0090] [Other Components in Curable Composition] The curable composition is sufficient as long as it contains at least the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton and the naphthylmethyl (meth)acrylate (B) as polymerizable components, and may or may not contain other components different from these, as necessary.

[0091] Examples of other components include polyfunctional or monofunctional polymerizable components (polymerization components or monomer components) that do not belong to the categories of the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton and the naphthylmethyl (meth)acrylate (B), polymerization initiators, solvents, additives, and the like.

[0092] (Polyfunctional Polymerizable Component) The other polyfunctional polymerizable component different from the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton is not particularly limited, and examples thereof include other polyfunctional (meth)acrylates (second polyfunctional (meth)acrylates). The polyfunctional (meth)acrylate may be a compound having a plurality (two or more) (meth)acryloyl groups, and the number of (meth)acryloyl groups per molecule is, for example, 2 to 10, preferably 2 to 6, more preferably 2 to 4, among which 2 to 3 is preferred, and 2 is particularly preferred.

[0093] Examples of the second polyfunctional (meth)acrylate include epoxy (meth)acrylates (vinyl ester resins) such as aliphatic epoxy (meth)acrylates, alicyclic epoxy (meth)acrylates, aromatic epoxy (meth)acrylates, and poly(meth)acrylates of novolac epoxy resins; urethane (meth)acrylates; polyester (meth)acrylates (poly(meth)acrylates of polyester polyols having two or more hydroxyl groups); alkylene glycol di(meth)acrylates; polyalkylene glycol di(meth)acrylates; di(meth)acrylates of alicyclic diols; di(meth)acrylates of biphenols or bisphenols or alkylene oxide (alkylene carbonate or haloalkanol) adducts thereof; and poly(meth)acrylates of low molecular weight polyol compounds having about 3 to 6 hydroxyl groups or alkylene oxide (alkylene carbonate or haloalkanol) adducts thereof.

[0094] Examples of the aliphatic epoxy (meth)acrylate include di(meth)acrylates of (poly)alkylene glycol diglycidyl ethers such as di(meth)acrylate of 1,6-hexanediol diglycidyl ether and di(meth)acrylate of polypropylene glycol diglycidyl ether.

[0095] Examples of the alicyclic epoxy (meth)acrylate include C 1,4-cyclohexanedimethanol diglycidyl ether di(meth)acrylate. ５－１０ Examples include di(meth)acrylates of epoxy compounds having an aliphatic ring.

[0096] Examples of the aromatic epoxy (meth)acrylate include di(meth)acrylates of diglycidyl ethers of bisphenols or biphenols, such as di(meth)acrylate of bisphenol A diglycidyl ether, or diglycidyl ethers of their alkylene oxide (alkylene carbonate or haloalkanol) adducts. Examples of bisphenols include bisphenol A, bisphenol F, bisphenol AD, and bisphenol S. Examples of biphenols include p,p'-biphenol, m,m'-biphenol, and o,o'-biphenol.

[0097] Examples of the alkylene glycol di(meth)acrylate include C alkylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, and the like. ２－１０ Alkylene glycol di(meth)acrylates are exemplified.

[0098] Examples of the polyalkylene glycol di(meth)acrylate include di- to hexa-C di(meth)acrylate such as diethylene glycol di(meth)acrylate. ２－１０ Alkylene glycol di(meth)acrylates are exemplified.

[0099] Examples of the di(meth)acrylate of the alicyclic diol include C di(meth)acrylate of 1,4-cyclohexanedimethanol. ５－１０ Examples include di(meth)acrylates of diol compounds having an aliphatic ring.

[0100] In the di(meth)acrylates of biphenols or bisphenols or their alkylene oxide (alkylene carbonate or haloalkanol) adducts, examples of the biphenols or bisphenols include the biphenols or bisphenols exemplified in the section on aromatic epoxy (meth)acrylates, 9,9-bis[hydroxyaryl]fluorene, etc.

[0101] Examples of the poly(meth)acrylate of a low molecular weight polyol compound having about 3 to 6 hydroxyl groups or an alkylene oxide (alkylene carbonate or haloalkanol) adduct thereof include glycerin tri(meth)acrylate, diglycerin tetra(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and sorbitol tri- or hexa(meth)acrylate.

[0102] The other polyfunctional polymerizable component [or second polyfunctional (meth)acrylate] may be contained alone or in combination of two or more kinds. As the second polyfunctional (meth)acrylate, a commercially available product may be used.

[0103] Among the second polyfunctional (meth)acrylates, low-viscosity polymerizable components, such as alkylene glycol di(meth)acrylate and polyalkylene glycol di(meth)acrylate, may be used as a reactive diluent.

[0104] The proportion of the other polyfunctional polymerizable component [or the second polyfunctional (meth)acrylate] relative to all polymerizable components in the curable composition is, for example, 0 to 50 mass%, preferably 30 mass% or less, 10 mass% or less, and 5 mass% or less in the following stepwise manner.

[0105] (Monofunctional Polymerizable Component) The other monofunctional polymerizable component is not particularly limited as long as it does not fall within the category of the (meth)acrylate (A) having a 9,9-bisarylfluorene skeleton and the naphthylmethyl (meth)acrylate (B). Typically, many of these are low-viscosity compounds, which may function as reactive diluents. The other monofunctional polymerizable component (or reactive diluent) may be a compound having a polymerizable group (or polymerizable unsaturated bond), for example, a group having an ethylenically unsaturated bond, specifically, a vinyl group, an alkenyl group such as an allyl group, or a (meth)acryloyl group. Specific examples of the monofunctional vinyl monomer include monofunctional vinyl monomers and monofunctional (meth)acrylic monomers. Examples of the monofunctional vinyl monomer include α-olefin monomers such as ethylene and propylene; styrene monomers such as styrene, α-methylstyrene, and vinyltoluene; vinyl ester monomers such as vinyl acetate; and N-vinylpyrrolidone. Examples of the monofunctional (meth)acrylic monomer include (meth)acrylic acid; (meth)acrylamide; N-substituted (meth)acrylamides such as N-methylol(meth)acrylamide and N,N-dimethyl(meth)acrylamide; (meth)acrylonitrile; and monofunctional (meth)acrylates.

[0106] These monofunctional polymerizable components may be used alone or in combination of two or more. Among these monofunctional polymerizable components, monofunctional (meth)acrylic monomers such as monofunctional (meth)acrylates are preferred.

[0107] Examples of the monofunctional (meth)acrylate include aliphatic monofunctional (meth)acrylates, alicyclic monofunctional (meth)acrylates, aromatic monofunctional (meth)acrylates, and sulfur atom-containing monofunctional (meth)acrylates. These monofunctional (meth)acrylates may be used alone or in combination.

[0108] Examples of the aliphatic monofunctional (meth)acrylate include C acrylates such as methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. １－２０ Examples include alkyl (meth)acrylates.

[0109] Examples of the alicyclic monofunctional (meth)acrylate include C cyclohexyl (meth)acrylate. ５－１０ Examples include bridged cyclic (meth)acrylates such as cycloalkyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and isobornyl (meth)acrylate.

[0110] Examples of aromatic monofunctional (meth)acrylates include aryl (meth)acrylates such as phenyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; and aryloxyalkyl (meth)acrylates, specifically, C aryloxyalkyl (meth)acrylates such as 2-phenoxyethyl (meth)acrylate, 2-(2-naphthoxy)ethyl (meth)acrylate, and 2-(o-phenylphenoxy)ethyl (meth)acrylate. ６－１２ Aryloxy C ２－４ alkyl(meth)acrylates; mono(meth)acrylates of bisphenols or biphenols (or alkylene oxide adducts thereof), such as the mono(meth)acrylate of an ethylene oxide adduct of bisphenol A; and (meth)acrylates having a fluorene skeleton, such as 9-(meth)acryloyloxymethylfluorene.

[0111] Examples of the monofunctional (meth)acrylate containing a sulfur atom include alkylthio(meth)acrylate, arylthio(meth)acrylate, aralkylthio(meth)acrylate, and arylthioalkyl(meth)acrylate. Examples of the alkylthio(meth)acrylate include C alkylthio(meth)acrylates such as methylthio(meth)acrylate. １－６ Examples of the arylthio(meth)acrylate include C alkylthio(meth)acrylates such as phenylthio(meth)acrylate. ６－１０ Examples of the aralkylthio(meth)acrylate include C arylthio(meth)acrylate such as benzylthio(meth)acrylate. ６－１０ Aryl C １－６Examples of the arylthioalkyl(meth)acrylate include C alkylthio(meth)acrylates such as phenylthioethyl(meth)acrylate. ６－１０ Arylthio C ２－４ Examples include alkyl (meth)acrylates.

[0112] The proportion of other monofunctional polymerizable components [particularly, monofunctional (meth)acrylic monomers such as monofunctional (meth)acrylates] is, for example, 0 to 50 mass %, preferably 30 mass % or less, 10 mass % or less, and 5 mass % or less in the following stepwise manner, relative to all polymerizable components in the curable composition.

[0113] (Polymerization Initiator) The polymerization initiator may be a thermal polymerization initiator (thermal radical generator) or a photopolymerization initiator (photoradical generator).

[0114] Examples of the thermal polymerization initiator include organic peroxides and azo compounds. Examples of the organic peroxides include dialkyl peroxides such as di-t-butyl peroxide; diacyl peroxides such as lauroyl peroxide and benzoyl peroxide; peracids (or peresters) such as t-butyl hydroperoxide, cumene hydroperoxide, and t-butyl peracetate; ketone peroxides; peroxycarbonates; and peroxyketals. Examples of the azo compounds include azonitrile compounds such as 2,2'-azobis(isobutyronitrile), azoamide compounds, and azoamidine compounds. These thermal polymerization initiators may be used alone or in combination.

[0115] Examples of photopolymerization initiators include benzoins, specifically benzoin alkyl ethers such as benzoin and benzoin ethyl ether; acetophenones such as acetophenone; α-hydroxyphenones such as 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1-hydroxycyclohexyl-phenyl ketone; aminoacetophenones such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinoaminopropanone-1; anthraquinones such as anthraquinone and 2-methylanthraquinone; thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone; xanthones; and benzoylphosphine oxides such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. These photopolymerization initiators may be used alone or in combination of two or more. Preferred photopolymerization initiators include α-hydroxyphenones, benzoylphosphine oxides, and combinations thereof.

[0116] The proportion of the polymerization initiator (thermal and / or photopolymerization initiator) relative to 100 parts by mass of the total amount of the polymerizable components in the curable composition is, for example, 0.1 to 15 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 2 to 5 parts by mass.

[0117] The photopolymerization initiator may be combined with a photosensitizer. Typical examples of the photosensitizer include conventional photosensitizers such as tertiary amines, for example, trialkylamines; trialkanolamines such as triethanolamine; dialkylaminobenzoic acid alkyl esters, specifically, N,N-dimethylaminobenzoic acid ethyl esters such as p-(dimethylamino)benzoic acid ethyl esters, and N,N-dimethylaminobenzoic acid amyl esters such as p-(dimethylamino)benzoic acid amyl esters; bis(dialkylamino)benzophenones such as 4,4-bis(diethylamino)benzophenone; and dialkylaminobenzophenones such as 4-(dimethylamino)benzophenone. These photosensitizers may be used alone or in combination of two or more.

[0118] The proportion of the photosensitizer is, for example, 1 to 200 parts by mass, preferably 5 to 150 parts by mass, and more preferably 10 to 100 parts by mass, relative to 100 parts by mass of the polymerization initiator.

[0119] (Solvent) The curable composition may not contain a solvent because it can be easily adjusted to a low viscosity, but may contain a solvent as needed to adjust handleability. The solvent is not particularly limited, and examples thereof include hydrocarbons, specifically, aliphatic hydrocarbons such as hexane and heptane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons, specifically, methylene chloride, chloroform, 1,2-dichloroethane, and chlorobenzene; ethers, specifically, chain ethers such as diethyl ether, and cyclic ethers such as tetrahydrofuran and 1,4-dioxane; ketones, specifically, dialkyl ketones such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK), and cyclohexanone. Examples of suitable solvents include cyclic ketones, esters, specifically acetate esters such as methyl acetate, ethyl acetate, and butyl acetate, glycol ether acetates, specifically (poly)alkylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate (PGMEA) and diethylene glycol monobutyl ether acetate, sulfoxides, specifically dimethyl sulfoxide, amides, specifically N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, and nitriles, specifically acetonitrile. These solvents may be used alone or in combination as a mixed solvent of two or more.

[0120] The proportion of the solvent is not particularly limited, and the composition may be prepared so that the concentration of the solid content (components other than the solvent) is, for example, about 0.1 to 50 mass %, specifically about 20 to 50 mass %, preferably 25 to 40 mass %, and more preferably 30 to 35 mass %, relative to the entire curable composition.

[0121] (Additives) The curable composition may contain conventional additives such as colorants, stabilizers, fillers, antistatic agents, flame retardants, surfactants, plasticizers, curing agents, and polymerization inhibitors. Examples of the stabilizers include heat stabilizers, antioxidants, and ultraviolet absorbers. These additives may be used alone or in combination.

[0122] The total proportion of the additives is, for example, about 30% by mass or less, preferably 20% by mass or less, 10% by mass or less, and 5% by mass or less in a stepwise manner, relative to the total solid content (components other than the solvent) of the curable composition, and may be, for example, about 0.001 to 15% by mass, specifically about 0.01 to 3% by mass.

[0123] [Characteristics of Curable Composition] The refractive index (refractive index before curing) nD of the curable composition may be, for example, about 1.56 to 1.7 at a temperature of 25°C and a wavelength of 589 nm, and is preferably 1.57 to 1.65, 1.58 to 1.64, 1.59 to 1.63, 1.6 to 1.625, 1.605 to 1.62, and 1.61 to 1.615 in the following stepwise order; when a high refractive index is particularly important, it may be, for example, about 1.6 to 1.645, and is preferably 1.605 to 1.64, 1.61 to 1.635, 1.615 to 1.63, and 1.62 to 1.625 in the following stepwise order.

[0124] The viscosity of the curable composition at a temperature of 25°C may be, for example, about 10 to 200,000 mPa·s, preferably in the following stepwise manner: 100 to 100,000 mPa·s, 500 to 50,000 mPa·s, 1,000 to 30,000 mPa·s, 1,500 to 10,000 mPa·s, 2,000 to 5,000 mPa·s, 2,500 to 4,000 mPa·s; when a low viscosity is particularly important, preferably in the following stepwise manner: 100 to 3,000 mPa·s, 150 to 2,000 mPa·s, 200 to 1,000 mPa·s, 250 to 500 mPa·s.

[0125] The curable composition has excellent storage stability, and may not produce precipitates even after, for example, 10 days or more, preferably 20 days or more, and more preferably 30 days or more (e.g., about 30 to 40 days) at a temperature of 25°C, more preferably 60 days or more (e.g., about 90 to 180 days), and particularly preferably 120 days or more (e.g., about 120 to 150 days).

[0126] The curable composition has excellent curability, and at a temperature of 25°C, it has a curing rate of, for example, 2000 mJ / cm ２about 500 to 2000 mJ / cm ２ ), preferably 1000 mJ / cm ２ More preferably, 500 mJ / cm or less ２ It is also possible to form a cured product (cured film) with a thickness of about 100 μm that has no tackiness (adhesiveness) on the surface by irradiating the film with a high-pressure mercury lamp (or UV) at the following integrated light amount.

[0127] In this specification and claims, the refractive index, viscosity, storage stability and curability of the curable composition can be measured by the methods described in the examples below.

[0128] [Cured Product] The present disclosure encompasses a cured product of a curable composition containing at least (A) a (meth)acrylate having a 9,9-bisarylfluorene skeleton and (B) naphthylmethyl (meth)acrylate, and a method for producing the same.

[0129] A cured product can be produced by a step of curing the curable composition (curing step). In the curing step, the curable composition is cured by applying active energy (or active energy rays) to produce a cured product. The active energy can be thermal energy and / or light energy, such as ultraviolet (UV) rays or X-rays.

[0130] When light energy such as ultraviolet (UV) is used for light irradiation, the amount of light irradiation energy (or cumulative light amount) can be appropriately selected depending on the type of components in the composition, the intended use, etc., and is, for example, 50 to 10,000 mJ / cm ２ , preferably 70 to 8000 mJ / cm ２ , more preferably 100 to 5000 mJ / cm ２ , particularly 500 to 3000 mJ / cm ２ is.

[0131] When heat treatment is carried out using thermal energy, the heating temperature is, for example, 50 to 200°C, preferably 60 to 150°C, and more preferably 70 to 120°C.

[0132] The shape of the cured product is not particularly limited, and may be, depending on the application, for example, a three-dimensional structure such as a lens or tube, a two-dimensional structure (or cured film) such as a film, sheet, or plate, or a one-dimensional structure such as a line, fiber, or rod.

[0133] The cured product may be produced by molding the curable composition or casting (injecting) it into a predetermined mold depending on its shape, and then subjecting it to a curing treatment (heating and / or light irradiation) in a curing step. Furthermore, in the case of a cured product having a two-dimensional structure, for example, the curable composition may be applied to a substrate or base, for example, a metal such as aluminum; an inorganic material or ceramic such as titanium oxide, glass, or quartz; an organic material or plastic such as a cyclic olefin resin or polycarbonate resin; or a porous body such as wood, preferably a transparent substrate, to form a film-like coating (or thin film), and then subjecting it to a curing treatment.

[0134] The refractive index (refractive index after curing) nD of the cured product at a temperature of 25°C and a wavelength of 589 nm may be, for example, about 1.57 to 1.7, preferably in the following stepwise order: 1.58 to 1.67, 1.59 to 1.66, 1.6 to 1.65, 1.62 to 1.645, 1.625 to 1.64, 1.63 to 1.635; when a high refractive index is particularly important, it may be, for example, about 1.62 to 1.665, preferably in the following stepwise order: 1.625 to 1.66, 1.63 to 1.655, 1.635 to 1.65, 1.64 to 1.645.

[0135] The 5% weight loss temperature of the cured product may be, for example, about 150 to 500°C, and preferably the following stepwise temperatures: 180 to 400°C, 200 to 350°C, 210 to 320°C, 220 to 300°C, 230 to 290°C, 240 to 280°C, and 250 to 270°C.

[0136] The glass transition temperature Tg of the cured product may be, for example, about 10 to 200°C, and preferably may be 50 to 150°C, 70 to 140°C, 80 to 130°C, 90 to 120°C, or 100 to 110°C in the following stepwise manner; when high flexibility (or bending durability) is particularly important, it is preferably 20 to 40°C and 25 to 35°C in the following stepwise manner.

[0137] The cured product may have excellent flexibility (or bending durability), and may be, for example, a cured product (cured film) having a film thickness of about 100 μm at a temperature of 25° C. that does not crack even when bent 180°. Furthermore, even when a cured product (cured film) having a film thickness of about 100 μm at a temperature of 25° C. is repeatedly bent, for example, 10,000 times or more (e.g., about 50,000 to 1,000,000 times), preferably 100,000 times or more (e.g., about 150,000 to 500,000 times), and more preferably 180,000 times or more (e.g., about 200,000 to 300,000 times), the cured film may not develop creases or breaks (no abnormalities may be observed in appearance).

[0138] In this specification and claims, the refractive index, 5% weight loss temperature, glass transition temperature Tg, flexibility and bending durability of the cured product can be measured by the methods described in the examples below.

[0139] [Representative Configuration] Representative curable compositions of the present disclosure include curable compositions containing a (meth)acrylate represented by the above formula (1) as a (meth)acrylate having a 9,9-bisarylfluorene skeleton, and naphthylmethyl (meth)acrylate. Among these, the following curable compositions (I) to (III) are preferred:

[0140] (Curable composition (I)) The curable composition (I) is a compound represented by the formula (1), １ is a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group (e.g., C １－１０ m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ are independently C groups such as a benzene ring, a naphthalene ring, and a biphenyl ring. ６－１２ represents an arene ring, R ２ａ and R ２ｂ are independently a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group (e.g., C １－１０ m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ is independently C ２－４a curable composition comprising: a (meth)acrylate which represents an alkylene group, and n1a and n1b independently represent a number from 0 to 3, or n1a + n1b represent a number from 0 to 6; and naphthylmethyl (meth)acrylate, wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate (former / latter) (mass ratio) is 20 / 80 to 80 / 20 (preferably 25 / 75 to 75 / 25);

[0141] A preferred curable composition (I) is a compound represented by the formula (1): １ is C １－６ alkyl groups such as alkyl groups, C ６－１０ an aryl group such as an aryl group or C ６－１０ Aryl C １－４ represents an aralkyl group such as an alkyl group, m1 represents an integer of 0 to 2, Z １ａ and Z １ｂ are independently C groups such as benzene ring and naphthalene ring. ６－１０ represents an arene ring, R ２ａ and R ２ｂ is independently C １－６ alkyl groups such as alkyl groups, C ６－１０ an aryl group such as an aryl group or C ６－１０ Aryl C １－４ m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ is independently C ２－３ a curable composition comprising: a (meth)acrylate which represents an alkylene group, and n1a and n1b independently represent a number from 0 to 2, or n1a + n1b represent a number from 0 to 4; and naphthylmethyl (meth)acrylate, wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate (former / latter) (mass ratio) is 30 / 70 to 70 / 30 (preferably 35 / 65 to 65 / 35);

[0142] A more preferred curable composition (I) is a curable composition having, in the formula (1), １ is C １－４ an alkyl group such as an alkyl group (preferably a C １－３ m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ each independently represents a benzene ring; R ２ａ and R ２ｂ is independently C １－４ an alkyl group such as an alkyl group (preferably a C １－３ m2a and m2b each independently represent an integer of 0 to 2 (preferably 0 or 1); １ａ and A １ｂ are independently an ethylene group or a propylene group (preferably an ethylene group), and n1a and n1b are independently a number from 0 to 2 (preferably a number from 0 to 1), or n1a + n1b are a number from 0 to 3 (preferably a number from 0 to 2), and a naphthylmethyl (meth)acrylate [preferably 1-naphthylmethyl (meth)acrylate], wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate is the former / latter (mass ratio) = 40 / 60 to 60 / 40 (preferably 45 / 55 to 55 / 45).

[0143] (Curable composition (II)) The curable composition (II) is a compound represented by the formula (1), １ is a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group (e.g., C １－１０ m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ are independently C groups such as a benzene ring, a naphthalene ring, and a biphenyl ring. ６－１２ represents an arene ring, R ２ａ and R ２ｂ are independently a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group (e.g., C １－１０m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ is independently C ２－４ a curable composition comprising: a (meth)acrylate which represents an alkylene group, and n1a and n1b independently represent a number from 3 to 10, or n1a + n1b represent a number from 6 to 20; and naphthylmethyl (meth)acrylate, wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate (former / latter) (mass ratio) is 20 / 80 to 98 / 2 (preferably 30 / 70 to 95 / 5);

[0144] A preferred curable composition (II) is a compound represented by the formula (1): １ is C １－６ alkyl groups such as alkyl groups, C ６－１０ an aryl group such as an aryl group or C ６－１０ Aryl C １－４ represents an aralkyl group such as an alkyl group, m1 represents an integer of 0 to 2, Z １ａ and Z １ｂ are independently C groups such as benzene ring and naphthalene ring. ６－１０ represents an arene ring, R ２ａ and R ２ｂ is independently C １－６ alkyl groups such as alkyl groups, C ６－１０ an aryl group such as an aryl group or C ６－１０ Aryl C １－４ m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ is independently C ２－３a (meth)acrylate which represents an alkylene group, and n1a and n1b independently represent a number from 4 to 9 (preferably a number from 4 to 8), or n1a + n1b represent a number from 7 to 18 (preferably a number from 8 to 16); and naphthylmethyl (meth)acrylate, wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate is the former / latter (mass ratio) = 40 / 60 to 92 / 8 (preferably 50 / 50 to 90 / 10);

[0145] A more preferred curable composition (II) is a compound represented by the formula (1): １ is C １－４ an alkyl group such as an alkyl group (preferably a C １－３ m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ each independently represents a benzene ring; R ２ａ and R ２ｂ is independently C １－４ an alkyl group such as an alkyl group (preferably a C １－３ m2a and m2b each independently represent an integer of 0 to 2 (preferably 0 or 1); １ａ and A １ｂ are independently an ethylene group or a propylene group (preferably an ethylene group), and n1a and n1b are independently a number from 5 to 7 (preferably a number from 5 to 6), or n1a + n1b are a number from 9 to 14 (preferably a number from 10 to 12), and a naphthylmethyl (meth)acrylate [preferably 1-naphthylmethyl (meth)acrylate], wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate is the former / latter (mass ratio) = 55 / 45 to 85 / 15 (preferably 60 / 40 to 80 / 20, more preferably 65 / 35 to 75 / 25, and particularly 67 / 33 to 73 / 27).

[0146] (Curable composition (III)) The curable composition (III) is a compound represented by the formula (1), １ is a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group (e.g., C １－１０ m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ are independently a polycyclic arene ring (preferably a C ring such as a naphthalene ring or a biphenyl ring) １０－２０ polycyclic arene ring, etc.), R ２ａ and R ２ｂ are independently a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group (e.g., C １－１０ m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ is independently C ２－４ a curable composition comprising: a (meth)acrylate having an alkylene group, wherein n1a and n1b independently represent a number from 0 to 3, or n1a + n1b represents a number from 0 to 6; and naphthylmethyl (meth)acrylate, wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate (former / latter) (mass ratio) is 10 / 90 to 80 / 20 (preferably 12 / 88 to 60 / 40);

[0147] A preferred curable composition (III) is a compound represented by the formula (1): １ is C １－６ alkyl groups such as alkyl groups, C ６－１４ an aryl group such as an aryl group or C ６－１０ Aryl C １－４ m1 represents an integer of 1 to 2; Z represents an aralkyl group such as an alkyl group (preferably an aryl group or an aralkyl group); １ａ and Z １ｂ is independently C １０－１８ represents a polycyclic arene ring, R ２ａ and R ２ｂ is independently C １－６ alkyl groups such as alkyl groups, C ６－１４ an aryl group such as an aryl group or C６－１０ Aryl C １－４ A represents an aralkyl group such as an alkyl group (preferably an aralkyl group), m2a and m2b independently represent an integer of 0 to 2, １ａ and A １ｂ is independently C ２－３ a curable composition comprising: a (meth)acrylate which represents an alkylene group, and n1a and n1b independently represent a number from 0 to 2, or n1a + n1b represent a number from 0 to 4; and naphthylmethyl (meth)acrylate, wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate (former / latter) (mass ratio) is 15 / 85 to 50 / 50 (preferably 18 / 82 to 45 / 55);

[0148] A more preferred curable composition (III) is a curable composition having, in the formula (1), １ is an aryl group (preferably a C group such as a phenyl group, a naphthyl group, or a biphenyl group) ６－１２ an aryl group, more preferably C ６－１０ aryl group, particularly naphthyl group), m1 represents an integer of 1 to 2, Z １ａ and Z １ｂ is independently C １０－１４ Polycyclic arene ring (preferably a C ring such as a naphthalene ring or a biphenyl ring) １０－１２ polycyclic arene ring), R ２ａ and R ２ｂ are independently an aralkyl group (preferably a phenyl C group such as a benzyl group). １－３ m2a and m2b each independently represent an integer of 0 to 2 (preferably 0 or 1); １ａ and A １ｂare independently an ethylene group or a propylene group (preferably an ethylene group), and n1a and n1b are independently a number from 0 to 2 (preferably a number from 0 to 1), or n1a + n1b are a number from 0 to 3 (preferably a number from 0 to 2), and a naphthylmethyl (meth)acrylate [preferably 1-naphthylmethyl (meth)acrylate], wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton [particularly, the (meth)acrylate represented by formula (1)] to the naphthylmethyl (meth)acrylate is the former / latter (mass ratio) = 20 / 80 to 40 / 60 (preferably 25 / 75 to 35 / 65).

[0149] The curable compositions (I) to (III) may each be appropriately combined with the preferred embodiments disclosed in this specification.

[0150] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to these examples. Details of raw materials, evaluation methods, etc. are shown below.

[0151] [Raw materials] DNFPA: 9,9-bis(3-acryloyloxypropyl)-2,7-di(2-naphthyl)fluorene, synthesized in accordance with Example 1 of WO 2021 / 131942 BPEFA: 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (manufactured by Osaka Gas Chemicals Co., Ltd.) BPEF-9EOA: diacrylate of an adduct in which an average of 9 moles of ethylene oxide (EO) are added to 1 mole of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (BPEF), synthesized in accordance with the method described in Reference Example 4 of JP 2013-53310 A DNBBzOPPEFA: 9,9-bis[(3-benzyl-4-(2-acryloyloxyethoxy)-5-phenyl)phenyl]fluorene, synthesized in Synthesis Example 1 described below. NMT-A: 1-naphthylmethyl acrylate, "Light Acrylate NMT-A" manufactured by Kyoeisha Chemical Co., Ltd. POBA: m-phenoxybenzyl acrylate, "Light Acrylate POB-A" manufactured by Kyoeisha Chemical Co., Ltd. Photopolymerization initiator A: "IRGACURE 184" manufactured by Ciba Japan Co., Ltd. Photopolymerization initiator B: "Darocur TPO" manufactured by BASF Japan Ltd.

[0152] Synthesis Example 1 Synthesis of 9,9-bis[(3-benzyl-4-(2-acroyloxyethoxy)-5-phenyl)phenyl]-2,7-dinaphthylfluorene 33.83 g (0.1 mol) of 2,7-dibromo-9-fluorenone, 57.51 g (0.22 mol, 2.2 eq) of 2-benzyl-6-phenylphenol, 87.2 g of toluene, 11.8 g (0.48 mol) of p-toluenesulfonic acid monohydrate, and 1.2 g (0.04 mol) of dodecanethiol were placed in a separable flask and stirred under reflux conditions (110 to 120°C). The point at which the peak of 2,7-dibromo-9-fluorenone disappeared in LC (liquid chromatography) was defined as the end point. The mixture was then cooled to 80°C, and 68 g of N,N-dimethylformamide (DMF) was added to dissolve the mixture uniformly. The resulting solution was washed with 68 g of ion-exchanged water, and the aqueous layer was then removed. This washing procedure was repeated twice. The organic layer was azeotropically dehydrated to obtain 171.73 g of a solution containing 9,9-bis[(3-benzyl-4-hydroxy-5-phenyl)phenyl]-2,7-dibromofluorene (DBrBBzOPPF).

[0153] To the resulting solution, 20.14 g (0.22 mol, 2.2 eq), 10.06 g (0.7 mol), and 59 g of DMF were added, and the mixture was stirred under reflux conditions (110-120°C) under a nitrogen gas atmosphere. The end point was the point at which the monosubstituted product (a compound in which only one molecule of ethylene carbonate reacts with DBrBBzOPPF) was 3% or less as determined by liquid chromatography (LC), and the mixture was cooled to 80°C. 71.1 g of a 24% by mass aqueous NaOH solution was added, and the mixture was stirred at 80°C for 2 hours. After stirring, 67 g of DMF, 80 g of toluene, and 102 g of ion-exchanged water were added and dissolved, and the aqueous layer was removed. This procedure of adding 50 g of ion-exchanged water and removing the aqueous layer was repeated five times. The organic layer was concentrated, and methanol was added to obtain 124.7 g of crude crystals. The crude crystals were dissolved in 166 g of methyl isobutyl ketone (MIBK), and then ion exchange resins (+) K1221 and (-) K1261 were added. The mixture was stirred at 85°C for 2 hours, and then poured into a region covered with activated carbon on Celite and filtered. The solution was concentrated under reduced pressure, and 64.7 g (yield 69.7%) of 9,9-bis[(3-benzyl-4-(2-hydroxyethoxy)-5-phenyl)phenyl]-2,7-dibromofluorene (DBrBBzOPPEF) was obtained by crystallization from methanol.

[0154] 28.09 g (0.03 mol) of DBrBBzOPPEF, 11.42 g (0.066 mol, 2.2 eq) of 2-naphthylboronic acid, 49.83 g of MIBK, 7.0 g (0.066 mol) of sodium carbonate, 30.4 g of ion-exchanged water, 7.0 mg (0.03 mmol, 0.001 eq) of palladium acetate, and 13.2 mg (0.05 mmol, 0.002 eq) of triphenylphosphine were added, degassed under reduced pressure, and purged with nitrogen. The mixture was then stirred under reflux conditions (90-100°C). The end point was the disappearance of the peak for the monosubstituted product (a compound in which only one molecule of 2-naphthylboronic acid reacts with DBrBBzOPPEF) in LC. The mixture was then cooled to 80°C and the lower layer was removed. 18 g of ion-exchanged water was added for washing, and the aqueous layer was removed. This procedure was repeated three times. 3.1 g of activated carbon was added to the organic layer, and the mixture was stirred at 70°C for 1 hour and then filtered. 18 g of ion-exchanged water was added to the resulting solution, and the aqueous layer was removed. This procedure was repeated twice. The solution was concentrated under reduced pressure, and 24.5 g (yield 79.8%) of 9,9-bis[(3-benzyl-4-(2-hydroxyethoxy)-5-phenyl)phenyl]-2,7-di(2-naphthyl)fluorene (DNBBzOPPEF) was obtained by methanol crystallization.

[0155] 100.02 g (0.1 mol) of DNBBzOPPEF, 17.39 g (0.51 mol, 2.46 eq), 0.214 g (2.3 mmol, 0.02 eq), 98.21 g of toluene, and 2.8 g (0.014 mol) of p-toluenesulfonic acid monohydrate were added and stirred under reflux conditions (110-120 ° C) while discharging the water produced outside the system. The end point was determined by LC when the mono-substituted product (a compound in which only one molecule of acrylic acid has reacted with DNBBzOPPEF) reached 20% or less, and toluene was added. The mixture was washed once with 35 g of 20% by mass brine, once with 20% by mass brine and 10% by mass aqueous NaOH solution, twice with 35 g of 20% by mass brine, and twice with 35 g of ion-exchanged water. 25 g of activated carbon was added to the solution, followed by stirring at room temperature for 1 hour. The solution was filtered through Celite, and 0.012 g of methoquinone was added to the resultant solution, which was then concentrated under reduced pressure to obtain 90.1 g (yield 81.0%, HPLC purity 82.8%) of 9,9-bis[(3-benzyl-4-(2-acroyloxyethoxy)-5-phenyl)phenyl]-2,7-di(2-naphthyl)fluorene (DNBBzOPPEFA) represented by the following formula.

[0156]

[0157] The obtained DNBBzOPPEFA １ H-NMR and １３ The results of C-NMR are shown below.

[0158] １ H-NMR (CDCl ３ , 300MHz): δ (ppm) 3.44 (t, 4H), 4.03 (t, 8H), 5.73 (d, 2H), 6.02 (dd, 2H), 6.31 (d, 2H), 6.95-7.05 (m, 6H), 7 .10-7.19 (m, 8H), 7.20-7.34 (m, 6H), 7.40-7.53 (m, 8H), 7.65-7.74 (m, 6H), 7.83-7.91 (m, 8H), 7.97 (d, 2H)

[0159] １３ C-NMR (CDCl ３ ​​, 75MHz): δ (ppm) 36.2, 63.6, 65.0, 70.2, 120.8, 125.0, 125.7, 125.8, 125.9, 126.0, 126.4, 127.3, 127.7, 128.2, 128.3, 128.4, 128.5, 128.7, 129.0, 130.5, 131.1, 132.7, 133.7, 134.5, 134.6, 138.6, 138.7, 139.1, 140.8, 140.9, 141.5, 152.4, 153.0, 166.0

[0160] [Evaluation Method] (HPLC) Using an HPLC (high performance or high performance liquid chromatograph) apparatus "LC-2030" manufactured by Shimadzu Corporation and a column "ODS-80TM" manufactured by Tosoh Corporation, a sample was dissolved in acetonitrile and measured, and the HPLC purity [area %] was calculated.

[0161] ( １ H-NMR and １３ C-NMR) A sample was dissolved in a heavy solvent containing tetramethylsilane as an internal standard, and measured using a nuclear magnetic resonance spectrometer ("AVANCE III HD" manufactured by BRUKER).

[0162] (Refractive Index nD) The refractive indexes before and after curing [refractive indexes of the curable composition and cured product] were measured using a multi-wavelength Abbe refractometer ("DR-M2 (circulating constant temperature water bath 60-C3)" manufactured by Atago) at a temperature of 25°C and a wavelength of 589 nm (D-line). For measuring the refractive index before curing, a curable composition (polymerizable component) containing no photopolymerization initiator was used as the sample, and for measuring the refractive index after curing, a cured product (cured film) (rated "○" for curability) obtained in the evaluation of (curability) described below was used as the sample.

[0163] The refractive index of the DNFPA before curing in Comparative Example 1 was determined by extrapolating the concentration to 100% by mass on a calibration curve (an approximate straight line calculated by the least squares method) created by preparing solutions with concentrations of 25.0% by mass and 48.7% by mass, since the sample (DNFPA not containing a photopolymerization initiator) was solid at 25°C, and measuring the refractive index of the resulting solutions.

[0164] The refractive index of the cured product after curing of DNFPA in Comparative Example 1 was measured as follows. 3 parts by mass of photopolymerization initiator A was added to 100 parts by mass of the polymerizable component (DNFPA) collected in a brown bottle, and the mixture was diluted with toluene (dissolved by heating to 60°C). The resulting diluted solution (curable composition) was spin-coated (1000 rpm, 30 seconds) onto the surface of a silicon wafer measuring approximately 3 cm x 3 cm to form a coating film. This coating film was irradiated with UV (500 mJ / cm) using a high-pressure mercury lamp ("ECS-151U" manufactured by Eye Graphics Co., Ltd.). ２ ) to prepare a cured product (cured film with a thickness of several μm) with a non-tacky (adhesive) surface. Because the refractive index nD of the obtained cured product was high, it was measured using a high-speed spectroscopic ellipsometer ("M-2000" manufactured by J.A. Woollam Co.) to ensure measurement accuracy.

[0165] (Viscosity) The viscosity of the curable composition was measured at a temperature of 25°C using a TV-22 viscometer (cone-plate type, "TVE-22L" manufactured by Toki Sangyo Co., Ltd.) with optional rotors (01:1°34' x R24, 07:3° x R7.7) and rotation speeds (0.5 to 20 rpm) selected according to the viscosity to be measured. Note that a curable composition (polymerizable component) not containing a photopolymerization initiator was used as the sample.

[0166] (Storage Stability) The storage stability of the curable composition was evaluated by preparing the curable composition as follows.

[0167] That is, a sample (polymerizable component) was collected in a colorless transparent bottle ("Screw tube" manufactured by Maruemu Co., Ltd.), and 3 parts by mass of photopolymerization initiator A was added to 100 parts by mass of the total amount of the collected polymerizable component (2 parts by mass of photopolymerization initiator B was also added in Reference Example 3 and Example 8), and the mixture was heated to melt at 60°C and mixed to prepare a curable composition. The obtained curable composition (curable composition containing a photopolymerization initiator) was left to stand at room temperature (25°C) in a dark place for 4 months (120 days), and its condition was observed and evaluated according to the following criteria.

[0168] ◎: No precipitates appear after 4 months (120 days) ○: No precipitates appear after 1 month (30 days) ×: Precipitations appear within 1 month (30 days)

[0169] (Curability) The curability of the curable composition was evaluated by forming a cured product (cured film) as shown below.

[0170] Specifically, a sample (polymerizable component) was collected in a colorless, transparent bottle ("Screw tube" manufactured by Maruemu Co., Ltd.), and 3 parts by mass of photopolymerization initiator A was added to 100 parts by mass of the collected polymerizable component (2 parts by mass of photopolymerization initiator B was also added in Example 8). The mixture was heated to melt at 60°C and mixed to prepare a curable composition. This curable composition (curable composition containing a photopolymerization initiator) was applied to a TAC (cellulose acetate) film using an applicator to prepare a coating film with a thickness of approximately 100 μm. This coating film was irradiated with UV light at room temperature (25°C) using a high-pressure mercury lamp ("ECS-151U" manufactured by iGraphics Co., Ltd.) at the integrated light dose shown in Tables 1 to 4. The curability of the resulting coating film [cured product (cured film)] was evaluated based on the feel of its surface using the following criteria.

[0171] Good: No tackiness (stickiness) on the cured surface. Fair: Tackiness (stickiness) on the cured surface. Bad: Does not cure (sticky).

[0172] In Comparative Example 1, since DNFPA was a solid at 25°C, the curability was evaluated in the same manner as above, except that a coating film was prepared as shown below. That is, 3 parts by mass of photopolymerization initiator A was added to 100 parts by mass of the polymerizable component (DNFPA) collected in a brown bottle, and the mixture was diluted with toluene (dissolved by heating to 60°C). This diluted solution (curable composition) was applied to a TAC (cellulose acetate) film using an applicator to form a coating film (film thickness: approximately 100 μm).

[0173] In Reference Example 2, since DNBBzOPPEFA was solid at 25 ° C., the curability was evaluated in the same manner as above, except that a coating film was prepared as shown below. That is, 3 parts by mass of photopolymerization initiator A and 2 parts by mass of photopolymerization initiator B were added to 100 parts by mass of the polymerizable component (DNBBzOPPEFA) collected in a brown bottle, and the mixture was diluted with methyl ethyl ketone (MEK) (dissolved by heating to 60 ° C.). This diluted solution (curable composition) was applied to a TAC (cellulose acetate) film using an applicator to form a coating film (film thickness: approximately 100 μm).

[0174] (Glass Transition Temperature Tg) The glass transition temperature Tg (°C) of the cured product was measured using a differential scanning calorimeter (DSC, "Discovery DSC25" manufactured by TA Instruments) under a nitrogen gas atmosphere at a measurement temperature of 30 to 220°C (Comparative Examples 1 to 3, Examples 1 to 3, and Reference Examples 2 and 8) or -10 to 100°C (Comparative Example 4 and Examples 4 to 7) and a heating rate of 10°C / min. The samples used were prepared in the same manner as the cured products (cured films) obtained in the evaluation of curability (those rated as "○" for curability).

[0175] (5% Weight Loss Temperature) The 5% weight loss temperature [°C] of the cured product was measured using a thermogravimetry-differential thermal analyzer (TG-DTA, "Thermo Plus EVO2 TG-DTA8122" manufactured by Rigaku Corporation) under a nitrogen gas atmosphere at a measurement temperature of 30 to 450°C (Comparative Examples 1 and 2, Examples 1 to 3, and Reference Examples 2 and 8) or 30 to 350°C (Comparative Example 4 and Examples 4 to 7) at a heating rate of 10°C / min, and the temperature at which the mass of the sample (cured product) decreased by 5% was determined. The sample used was prepared in the same manner as the cured product (cured film) obtained in the evaluation of curability (those rated as "○" for curability).

[0176] (Flexibility (or Toughness)) The flexibility (or toughness) of the cured product (cured film) was evaluated by checking the state of a sample (cured film) with a film thickness of approximately 100 μm when bent 180° at room temperature (25° C.) and using the following criteria: The sample used was a cured film (single film) obtained by peeling off the TAC film from a product prepared in the same manner as the cured product (cured film) obtained in the evaluation of curability (those rated as "○" for curability).

[0177] ○...No cracks occur ×...Cracks occur

[0178] (Bending durability) The bending durability of the cured product (cured film) was evaluated by repeatedly bending a sample (cured film) with a film thickness of approximately 100 μm at room temperature (25° C.) using a bending tester (DMLHP-CS manufactured by YUASA SYSTEM Co., Ltd.) Note that the sample used was a cured film (single film) obtained by peeling off the TAC film from a cured product (cured film) prepared in the same manner as the curable product (cured film) obtained in the evaluation of curability (those rated as "○" for curability).

[0179] Specifically, as shown in Fig. 1(a), a pair of plates 12, 13 (a pair of plates for holding a film (cured film) 11) of a bending tester 10 were first fixed so that the film support surfaces 12a, 13a were positioned on the same plane, and the film (cured film) 11 was placed on the film support surfaces 12a, 13a. Next, the pair of plates 12, 13 were rotated (moved symmetrically) around the opposing plate ends 12b, 13b as base points (rotation centers) in a direction in which the film support surfaces 12a, 13a approached each other, resulting in the state shown in Fig. 1(b), i.e., the film support surfaces 12a, 13a facing each other across a distance R defined by a spacer (not shown) and ultimately parallel to each other (hereinafter, this movement operation is referred to as the "closing operation"). The distance R between the film support surfaces 12a, 13a was adjusted to 4 mm. After the closing operation, the pair of plates 12, 13 were rotated in the opposite direction to the closing operation to return to the state shown in Fig. 1(a) (a state in which the film mounting surfaces 12a, 13a were on the same plane) (hereinafter, this moving operation is referred to as the "opening operation"). While repeating this series of opening and closing operations (closing operations and opening operations), the surface of the film (cured film) 11 was visually observed to count the number of times the film was bent until creases appeared in the film or the film broke and showed an abnormal appearance.

[0180] Comparative Examples 1-2, 4-5 and Reference Example 2 Using the polymerizable components in the proportions shown in Tables 1-4, evaluations were carried out.

[0181] [Comparative Example 3, Reference Examples 1 and 3, and Examples 1 to 8] Each polymerizable component was mixed in the ratio shown in Tables 1 to 4, and the mixture (curable composition) obtained by heating and melting at 60°C was used for each evaluation.

[0182] The results are shown in Tables 1 to 4. In the tables, the numbers in parentheses in the column for polymerizable component indicate the compounding ratio [parts by mass], and the numbers in parentheses in the column for curability indicate the cumulative light dose [mJ / cm2] when preparing the cured product. ２ ] means.

[0183]

[0184]

[0185]

[0186]

[0187] As is clear from Tables 1 to 4, in Reference Example 1, which combined DNFPA in which aryl groups are bonded to the 1- to 8-positions of the fluorene skeleton with NMT-A, a composition with a high refractive index and low viscosity could be prepared, but precipitation of crystals was confirmed one day after blending, indicating poor storage stability. In contrast, in the Examples in which NMT-A was combined with a di(meth)acrylate having a 9,9-bisarylfluorene skeleton in which aryl groups are bonded to the 9,9-positions rather than the 1- to 8-positions, a curable composition was obtained that not only had an excellent balance of high refractive index and low viscosity, but also surprisingly good storage stability. Furthermore, Example 8 demonstrated that, unlike Reference Example 1, excellent storage stability was achieved as long as an aryl group was bonded to the 9,9-position, even if an aryl group was bonded to the 1- to 8-positions. On the other hand, Reference Example 3, in which conventional POBA was used instead of NMT-A, had lower storage stability than Example 8.

[0188] Furthermore, in the composition of Reference Example 1, even though it had a high refractive index and low viscosity, the curability was rated as "×" or "Δ" and it was difficult to prepare a cured product. In contrast, in the Examples, the curability was good and a cured product could be easily or efficiently prepared.

[0189] Among the Examples, Examples 4 to 7 are preferred in terms of excellent flexibility. In these Examples, even when the proportion of NMT-A having a rigid naphthalene skeleton was increased, the flexibility seen in Comparative Example 4 was maintained. In particular, it was surprising that Examples 4 to 7 maintained flexibility despite exhibiting a glass transition temperature Tg higher than room temperature (25°C), unlike Comparative Example 4. Furthermore, among Examples 4 to 7, Examples 4 to 5 had particularly excellent flexibility, and therefore also had good bending durability. Example 5 is more preferred from the viewpoint of being able to satisfy a good balance of flexibility as well as high refractive index, low viscosity, curability, heat resistance, and the like.

[0190] Among the Examples, Examples 1 to 3 and Example 8 are preferred in terms of the excellent balance between high refractive index and low viscosity and storage stability. For example, when Examples 2 and 3 of the present application are compared with Comparative Example 3 of the present application and Comparative Examples 4 and 5 of JP 2013-053310 A, it can be seen that Examples 2 and 3 of the present application are superior in the balance between high refractive index and low viscosity. Examples 2 and 8 are more preferred from the viewpoint of achieving a better balance of high refractive index, low viscosity, high storage stability, as well as curability, heat resistance, and the like. Among them, Example 2 is particularly preferred for applications where heat resistance is more important, and Example 8 is particularly preferred for applications where refractive index is more important.

[0191] The curable composition of the present disclosure or a cured product thereof exhibits excellent optical properties such as a high refractive index, and therefore may be used in a variety of applications, for example, coating agents or coating films, specifically, protective films for paints, inks, electronic devices, liquid crystal members, and the like; adhesives, pressure-sensitive adhesives; resin fillers; electric and electronic materials or electric and electronic components (electrical and electronic devices), specifically, antistatic agents, carrier transport agents, light-emitting bodies, organic photoreceptors, thermosensitive recording materials, photochromic materials, hologram recording materials, antistatic trays, conductive sheets, optical disks, inkjet printers, digital paper, color filters, organic EL elements, organic semiconductor lasers, dye-sensitized solar cells, sensors, EMI shielding films, and the like; mechanical materials or mechanical parts (devices), specifically, automotive materials or parts, aerospace-related materials or parts, sliding members, and the like.

[0192] In particular, it can be effectively used as an optical member (optical element) or optical material, and examples thereof include optical adhesives (sealants) or optical pressure-sensitive adhesives such as OCR (optical clear resin) and OCA (optical clear adhesive) tapes or films, optical films (optical sheets), optical lenses, prisms, holograms, and optical fibers.

[0193] Examples of optical films include polarizing films, polarizing elements and polarizing plate protective films that constitute polarizing films, retardation films, alignment films (alignment films), viewing angle widening (compensation) films, diffuser plates (films), prism sheets, light guide plates, brightness enhancement films, near-infrared absorbing films, reflective films, anti-reflection (AR) films, reflection reduction (LR) films, anti-glare (AG) films, transparent conductive (ITO) films, anisotropic conductive films (ACF), electromagnetic shielding (EMI) films, films for electrode substrates, films for color filter substrates, barrier films, color filter layers, black matrix layers, adhesive layers or release layers between optical films, etc. The optical film may be an optical film for displays such as liquid crystal displays (LCDs), organic electroluminescent displays (OLEDs), plasma displays (PDPs), field emission displays (FEDs), and electronic paper. Furthermore, the cured product (cured film) of the present disclosure can also improve flexibility or bending durability, and can therefore be effectively used as an optical film incorporated into displays or image display devices that are used by repeatedly bending (for example, the display portion of a foldable or rollable information terminal such as a foldable or rollable smartphone). Therefore, the present disclosure also encompasses a foldable or rollable information terminal containing the cured product (cured film), a method for improving the durability of a foldable or rollable information terminal (the bending durability of the display portion) using the cured product (cured film), and the like.

[0194] Examples of optical lenses include eyeglass lenses, contact lenses, camera lenses, VTR zoom lenses, pickup lenses, Fresnel lenses, solar condensing lenses, objective lenses, and rod lens arrays.

[0195] DESCRIPTION OF SYMBOLS 10... Bending tester 11... Film (cured film) 12, 13... Plate 12a, 13a... Film mounting surface 12a, 13a... Plate end

Claims

1. A curable composition comprising a (meth)acrylate having a 9,9-bisarylfluorene skeleton and naphthylmethyl (meth)acrylate.

2. The curable composition according to claim 1, wherein the (meth)acrylate having a 9,9-bisarylfluorene skeleton includes a (meth)acrylate represented by the following formula (1): (In the formula, R １ represents a substituent, m1 represents an integer of 0 to 8, Z １ａ and Z １ｂ each independently represents an arene ring; R ２ａ and R ２ｂ m2a and m2b each independently represent an integer of 0 or more; １ａ and A １ｂ each independently represents an alkylene group; n1a and n1b each independently represent a number of 0 or more; R ３ａ and R ３ｂ each independently represents a hydrogen atom or a methyl group.

3. In the formula (1), R １ represents a halogen atom, a hydrocarbon group, an alkoxy group, an acyl group, a nitro group, a cyano group or a substituted amino group; m1 represents an integer of 0 to 2; Z １ａ and Z １ｂ is independent and C ６－１８ represents an arene ring; R ２ａ and R ２ｂ each independently represents a halogen atom, a hydrocarbon group, an alkoxy group, an acyl group, a nitro group, a cyano group, or a substituted amino group; m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ is independent and C ２－４ The curable composition according to claim 2, wherein n1a and n1b each independently represent an alkylene group and each independently represents a number from 0 to 10.

4. In the formula (1), R １ represents a hydrocarbon group, m1 represents an integer of 0 to 2, Z １ａ and Z １ｂ is independent and C ６－１２ represents an arene ring; R ２ａ and R ２ｂ each independently represents a hydrocarbon group; m2a and m2b each independently represent an integer of 0 to 2; １ａ and A １ｂ is independent and C ２－３ The curable composition according to claim 2, wherein n1a and n1b each independently represent an alkylene group and each independently represents 0 to 8.

5. The curable composition according to any one of claims 1 to 4, wherein the ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton to the naphthylmethyl (meth)acrylate is the former / the latter (mass ratio) = 20 / 80 to 85 / 15.

6. The curable composition according to any one of claims 1 to 4, wherein a ratio of the (meth)acrylate having a 9,9-bisarylfluorene skeleton to the naphthylmethyl (meth)acrylate (the former / the latter (mass ratio) is from 40 / 60 to 80 / 20.

7. A cured product obtained by curing the curable composition according to any one of claims 1 to 4.

8. A method for producing a cured product, comprising the step of curing the curable composition according to any one of claims 1 to 4.

9. An optical component comprising the cured product according to claim 7.