WO2023058524A1 - Compound, resin, curable composition, cured product, and optical member - Google Patents

Abstract

The present invention provides: a compound which can exhibit a high refractive index; and an application of said compound.　One embodiment of the present invention relates to a compound represented by formula (1).　R1 is a hydrogen atom or an aryl group.　R2 is a divalent group containing at least two benzene rings, and the two R2 moieties may be the same as, or different from, each other.　a and b are each an integer between 0 and 6.　R3 R3 is an alkylene group. In a case where the value of (a+b) is 2 or more, the (a+b) R3 moieties may be the same as, or different from, each other.　c and d are each an integer between 1 and 10.　e is an integer between 0 and 5.　f is an integer between 0 and 4.　R4 is a substituent group. In a case where the value of (e+f) is 2 or more, the (e+f) R4 moieties may be the same as, or different from, each other.

Description

Compounds, resins, curable compositions, cured products and optical members

The present invention relates to compounds, resins, curable compositions, cured products and optical members.
This application is based on Japanese Patent Application No. 2021-163480 filed with the Japan Patent Office on October 4, 2021 and Japanese Patent Application No. 2022-143464 filed with the Japan Patent Office on September 9, 2022. , the contents of which are hereby incorporated by reference.

High refractive index resins are used in various optical members such as lenses and films for touch panels. As a high refractive index resin, a resin using a monomer having a fluorene skeleton is known (for example, Patent Documents 1 and 2).

Japanese Patent No. 5513825 Japanese Patent No. 6016303

However, the refractive index of conventional monomers having a fluorene skeleton is not fully satisfactory. 2. Description of the Related Art As devices such as portable equipment become thinner in recent years, optical members used in portable equipment and the like are also required to be thinner. From the viewpoint of thickness reduction of optical members, further increase in the refractive index of materials forming optical members is required.

The purpose of the present invention is to provide a compound capable of exhibiting a high refractive index and its use.

The present invention has the following aspects.
[1] A compound represented by the following formula (1).

In formula (1), R ¹ is a hydrogen atom or an aryl group,
R ² is a divalent group containing at least two benzene rings, two R ² may be the same or different,
a and b are each independently an integer of 0 to 6,
R ³ is an alkylene group, and when (a + b) is 2 or more, (a + b) R ³ may be the same or different,
c and d are each independently an integer of 1 to 10,
e is an integer from 0 to 5, f is an integer from 0 to 4,
R ⁴ is a substituent, and when (e+f) is 2 or more, (e+f) R ^4s may be the same or different.

[2] A compound represented by the following formula (2).

In formula (2), R ¹ is a hydrogen atom or an aryl group,
R ² is a divalent group containing at least two benzene rings, two R ² may be the same or different,
a and b are each independently an integer of 0 to 6,
R ³ is an alkylene group, and when (a + b) is 2 or more, (a + b) R ³ may be the same or different,
c and d are each independently an integer of 1 to 10,
X is a monovalent group containing a polymerizable functional group or a reactive functional group, or a hydrogen atom, (c + d) X may be the same or different, and at least one of (c + d) X is the monovalent group,
e is an integer from 0 to 5, f is an integer from 0 to 4,
R ⁴ is a substituent, and when (e+f) is 2 or more, (e+f) R ^4s may be the same or different.

[3] A resin having a structural unit based on the compound of [1] above.
[4] The resin of [3], which is a polycarbonate resin.
[5] The resin of [3], which is a polyester resin.
[6] A curable composition containing the compound of [2] above.
[7] A cured product of the curable composition of [6] above.
[8] An optical member containing the resin according to any one of [3] to [5].
[9] An optical member containing the cured product of [7].

According to the present invention, a compound capable of exhibiting a high refractive index and its use can be provided.

A compound according to one embodiment of the present invention (hereinafter also referred to as "compound (1)") is represented by the following formula (1).

In formula (1), R ¹ is a hydrogen atom or an aryl group.
^R2 is a divalent group containing at least two benzene rings, and two ^R2s may be the same or different.
a and b are each independently an integer of 0 to 6;
R ³ is an alkylene group, and when (a+b) is 2 or more, (a+b) R ³ may be the same or different.
c and d are each independently an integer of 1-10.
e is an integer of 0-5 and f is an integer of 0-4.
R ⁴ is a substituent, and when (e+f) is 2 or more, (e+f) R ^4s may be the same or different.

Examples of the aryl group for R ¹ include a phenyl group.
From the viewpoint of increasing the refractive index, R ¹ is preferably a phenyl group. A hydrogen atom is preferable from the viewpoint of ease of reactivity in synthesizing compound (1).

^R2 contains at least two benzene rings. Therefore, the refractive index is higher than when R ² contains one benzene ring or when it does not contain a benzene ring.

Examples of R ² include naphthylene group, phenanthrylene group, anthrylene group, 4,4′-biphenyl-diyl group, and 4,4′-diphenylether-diyl group.
Among these, a naphthylene group is preferable from the viewpoint of solubility in organic solvents. The naphthylene group includes, for example, a 1,2-naphthylene group and a 1,6-naphthylene group. Among these, a 1,2-naphthylene group is preferred from the standpoint of ease of production.

R ² may have a substituent. Substituents include, for example, a hydroxyl group, a cyano group, an acetyl group, and a halogen atom.

a and b are each independently an integer of 0 to 6;
When a is 0, the terminal OH of _HO- (R ³ O) a - bonds to R ² to form a phenolic hydroxyl group. When a is an integer of 1 or more, it binds to ^R3 to form an alcoholic hydroxyl group. The same applies to the terminal OH of —(OR ³ ) _b —OH.

In a preferred embodiment, a and b are 0. In this case, the hydroxyl group becomes a phenolic hydroxyl group. Therefore, when compound (1) is used as a raw material to make polycarbonate, polyester, or other compounds, it tends to have excellent reactivity.

In another preferred embodiment, a and b are integers of 1 or more. In this case, the hydroxyl group becomes an alcoholic hydroxyl group. Therefore, formation of a quinone structure caused by oxidation of the phenolic hydroxyl group is suppressed. As a result, it is possible to suppress discoloration such as yellowing due to aging and darkening of the discoloration in the resin or molded article using the compound (1). In this aspect, a and b are preferably 1 from the viewpoint of heat resistance.

The number of carbon atoms in the alkylene group in R ³ can be, for example, 2-10. The number of carbon atoms is preferably 2-4. Alkylene groups may be linear or branched. Examples of the alkylene group include ethylene group, trimethylene group, propylene group, butane-1,2-diyl group and hexylene group.

c and d are each independently an integer of 1-10.
When compound (1) is used as a raw material for polycarbonate or polyester, it is particularly preferred that c and d are 1.

The compound (1) can be used as it is as a curing agent for epoxy resins. The compound (1) can also be included in the curable composition after substituting the hydroxyl group thereof with a group containing a polymerizable functional group or a reactive functional group. In this case, c and d are each independently an integer of 1 to 4 because the crosslink density increases when the curable composition is cured, thereby increasing the mechanical strength and heat resistance of the cured product. is preferred.

e is an integer from 0 to 5. 0 is preferable from the viewpoint of ease of procurement of raw materials.

f is an integer from 0 to 4. 0 is preferable from the viewpoint of ease of procurement of raw materials.

Examples of substituents for R ⁴ include alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, hydroxyl groups, cyano groups, acetyl groups and halogen atoms.

<Method for producing compound (1)>
Examples of the method for producing compound (1) include a method including the following step A.
Step A: A biphenyl compound represented by the following formula (1a), a hydroxy compound represented by the following formula (1b), and a hydroxy compound represented by the following formula (1c) are reacted to obtain the following formula (1- A step of obtaining a compound represented by 1) (hereinafter also referred to as “compound (1-1)”).

In the production of compound (1), the following step B may be further performed after step A, if necessary.
Step B: A step of adding one or more oxyalkylene groups to the hydroxyl group of compound (1-1) obtained in step A.

(biphenyl compound)
In formula (1a), R ¹ , e, f, and R ⁴ are the same as described above.
Biphenyl compounds include, for example, 4-biphenylaldehyde, 4-bromo-4'-biphenylaldehyde, 4-benzoylbiphenyl, and 4-bromo-4'-benzoylbiphenyl. The biphenyl compounds may be used singly or in combination of two or more.
Among these, 4-biphenylaldehyde is preferable from the viewpoint of ease of raw material procurement. 4-bromo-4′-biphenylaldehyde is preferable in that having a bromine atom enables the resulting compound (1) to exhibit a higher refractive index.

(hydroxy compound)
In formulas (1b) and (1c), R ² , c and d are as described above.
The hydroxy compound represented by formula (1b) and the hydroxy compound represented by formula (1c) may be the same or different. Hereinafter, the hydroxy compound represented by the formula (1b) and the hydroxy compound represented by the formula (1c) are collectively referred to simply as "hydroxy compounds".

Examples of hydroxy compounds include 1-naphthol, 2-naphthol, 1-hydroxyanthracene, 2-hydroxyanthracene, 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, 4-hydroxybiphenyl and 2-hydroxybiphenyl. Hydroxy compounds may be used singly or in combination of two or more.
Among these, 1-naphthol and 2-naphthol are preferred from the viewpoint of ease of raw material procurement.

(Step A)
The molar ratio of the biphenyl compound and the hydroxy compound (biphenyl compound/hydroxy compound) in reacting the biphenyl compound and the hydroxy compound is preferably 0.001 to 0.85, more preferably 0.005 to 0.80.

If the molar ratio of the biphenyl compound/hydroxy compound is 0.85 or less, the compound (1-1) in which two molecules of the hydroxy compound are added to one molecule of the biphenyl compound is produced as the main component.

If the molar ratio of the biphenyl compound/hydroxy compound exceeds 0.85, the biphenyl compound and the hydroxy compound are likely to be added alternately, and as a result, the yield of compound (1-1) may decrease.

A biphenyl compound and a hydroxy compound are typically reacted in the presence of an acid catalyst. The use of an acid catalyst facilitates the reaction between the biphenyl compound and the hydroxy compound.

Examples of acid catalysts include inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; organic acids such as oxalic acid, acetic acid, citric acid, tartaric acid, benzoic acid and paratoluenesulfonic acid; organic acids such as zinc acetate and zinc borate. Salt; Ion-exchange resins having sulfone groups and carboxylic acid groups are exemplified. Among these, oxalic acid, hydrochloric acid, sulfuric acid, and p-toluenesulfonic acid are preferred in that the production of by-products due to side reactions is suppressed and at the same time, the catalyst can be easily removed by washing with water after the completion of the reaction. is preferred. The acid catalyst may be used alone or in combination of two or more.

The amount of acid catalyst used can be, for example, 0.01 to 100 parts by mass with respect to 100 parts by mass of the biphenyl compound.

When reacting the biphenyl compound and the hydroxy compound, a co-catalyst may be used, if necessary.
Examples of promoters include mercaptans such as methyl mercaptan, ethyl mercaptan, normal propyl mercaptan, isopropyl mercaptan, tertiary butyl mercaptan, stearyl mercaptan and dodecyl mercaptan. The co-catalyst may be used singly or in combination of two or more.

The amount of co-catalyst used can be, for example, 0.005 to 3.00 parts by mass with respect to 100 parts by mass of the biphenyl compound.

Process A can be carried out in the same manner as in the production of ordinary novolak-type phenolic resins.
For example, a reaction vessel is charged with a biphenyl compound, a hydroxy compound, an acid catalyst, a solvent, and, if necessary, a co-catalyst, and an arbitrary reaction temperature is maintained for an arbitrary reaction time to produce a product containing compound (1-1). can get.

Examples of the solvent include water such as ion-exchanged water; and organic solvents such as diethyl ether, cyclopentylmethyl ether, methanol, ethanol, benzene, toluene and xylene. One solvent may be used alone, or two or more solvents may be used in combination.
The reaction temperature can be, for example, 10-150°C. Reaction time can be, for example, 0.5 to 48 hours.

After the reaction is completed, extraction, washing with water, concentration, recrystallization, etc. may be performed as necessary.

(Step B)
At least one of a and b in the formula (1) is 1 or more by adding one or more oxyalkylene groups ((OR ³ ) _a , (OR ³ ) _b ) to the hydroxyl group of the compound (1-1). A compound (hereinafter also referred to as “compound (1-2)”) is obtained.

The method of adding one or more oxyalkylene groups is not particularly limited. Various attachment methods can be used. For example, a method of reacting the compound (1-1) with an alkylene oxide such as ethylene oxide can be mentioned.

<Use of compound (1)>
Since the compound (1) described above has the structure of the above formula (1), it can exhibit a high refractive index (for example, a refractive index of 0.62 to 0.78).
Here, in general, when the polarization of the entire molecule becomes large, there is a tendency to develop a high refractive index. One way to increase the polarization of the entire molecule is to increase the number of free-moving conjugated π electrons.
In the biphenyl site in compound (1), 12 π electrons present in two benzene rings resonate over a wide range of the entire biphenyl site. By further introducing two R ² containing at least two benzene rings into this biphenyl moiety, the number of conjugated π-electrons increases and the range in which the π-electrons resonate also widens. As a result, it is thought that the whole molecule becomes more easily polarized and exhibits a high refractive index.

Compound (1) has two or more hydroxyl groups. Therefore, compound (1) can be used as a monomer component for resins such as polycarbonate resins and polyester resins that contain a polyhydric hydroxy compound as a monomer component. A resin obtained from a monomer component containing the compound (1) can exhibit a high refractive index because it has structural units based on the compound (1).

A polycarbonate resin is an example of a resin containing a polyhydric hydroxy compound as a monomer component.
Examples of the polycarbonate resin obtained from the monomer component containing the compound (1) include polycarbonate resins having a structural unit represented by the following formula (a1) (hereinafter also referred to as "structural unit (a1)"). .

Structural unit (a1) is formed from compound (1) wherein c and d are 1 in formula (1) above.
The number of structural units (a1) that the polycarbonate resin has may be one, or two or more.

The polycarbonate resin may further have structural units other than the structural unit (a1).
Other structural units include, for example, structural units based on dihydroxy compounds other than compound (1) (hereinafter also referred to as "structural unit (a2)").
The structural unit (a2) is represented by the following formula (a2).

^R6 is a residue obtained by removing two hydroxyl groups from other dihydroxy compounds.
Other dihydroxy compounds are not particularly limited, and any of those known as monomer components for polycarbonate resins can be used.

Other dihydroxy compounds include, for example, aromatic dihydroxy compounds and aliphatic dihydroxy compounds.
Examples of aromatic dihydroxy compounds include phenol compounds such as hydroquinone and resorcin; bisphenol compounds such as bisphenol A, bisphenol F, bisphenol B, bisphenol AP, bisphenol C, bisphenol E, bisphenol S, bisphenol Z, bisphenol CDE and bisphenol fluorene. ; bisnaphtholfluorene, 4,4'-dihydroxybiphenyl.
Aliphatic dihydroxy compounds include, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol.
The number of structural units (a2) that the polycarbonate resin has may be one, or two or more.

The polycarbonate resin can be produced by a known method for producing a polycarbonate resin, except that the compound (1) is used as at least part of the monomer component (dihydroxy compound).

Another example of a resin containing a polyhydric hydroxy compound as a monomer component is a polyester resin.
Examples of the polyester resin obtained from the monomer component containing the compound (1) include polyester resins having a structural unit represented by the following formula (b1) (hereinafter also referred to as "structural unit (b1)"). .

^R5 is a residue obtained by removing two carboxy groups from a dicarboxylic acid.
The dicarboxylic acid is not particularly limited, and those known as monomer components for polyester resins can be used. Examples of dicarboxylic acids include terephthalic acid and 2,6-naphthalenedicarboxylic acid.

The structural unit (b1) is formed from the compound (1) in which c and d are 1 in the above formula (1) and a dicarboxylic acid.
The structural unit (b1) that the polyester resin has may be one type, or two or more types.

The polyester resin may further have structural units other than the structural unit (b1).
Other structural units include, for example, structural units represented by the following formula (b2) (hereinafter also referred to as “structural unit (b2)”).

R ⁶ is a residue obtained by removing two hydroxyl groups from another dihydroxy compound, and R ⁷ is a residue obtained by removing two carboxy groups from a dicarboxylic acid.
Other dihydroxy compounds and dicarboxylic acids are the same as those mentioned above.
The structural unit (b2) possessed by the polyester resin may be of one type or two or more types.

The above polyester resin can be produced by a known polyester resin production method, except that the compound (1) is used as at least part of the monomer component (dihydroxy compound).

Compound (1) can also be used to produce a compound represented by the following formula (2) (hereinafter also referred to as "compound (2)").

In formula (2), R ¹ is a hydrogen atom or an aryl group.
^R2 is a divalent group containing at least two benzene rings, and two ^R2s may be the same or different.
a and b are each independently an integer of 0 to 6;
R ³ is an alkylene group, and when (a+b) is 2 or more, (a+b) R ³ may be the same or different.
c and d are each independently an integer of 1-10.
X is a monovalent group containing a polymerizable functional group or a reactive functional group, or a hydrogen atom, (c + d) X may be the same or different, and at least one of (c + d) X is the above monovalent group.
e is an integer of 0-5 and f is an integer of 0-4.
R ⁴ is a substituent, and when (e+f) is 2 or more, (e+f) R ^4s may be the same or different.

In formula (2), R ¹ , R ² , a, b, R ³ , c, d, e, f, and R ⁴ are the same as described above.
The polymerizable functional group for X is not particularly limited as long as it is polymerizable. For example, a (meth)acryloyl group is mentioned. A (meth)acryloyl group means an acryloyl group or a methacryloyl group.

Examples of reactive functional groups in X include epoxy groups, acid anhydride groups, and amino groups.
When X has a reactive functional group, compound (2) is typically combined with a cross-linking agent having two or more functional groups capable of reacting with the reactive functional group of X.
Functional groups capable of reacting with epoxy groups include, for example, amino groups, acid anhydride groups, and hydroxyl groups.
Examples of functional groups capable of reacting with acid anhydride groups include amino groups and hydroxyl groups.
Functional groups that can react with amino groups include, for example, acid anhydride groups.

The number of polymerizable functional groups or reactive functional groups possessed by X may be one or two or more, but typically one.
The polymerizable functional group or reactive functional group may be directly bonded to the oxygen atom adjacent to X, or may be bonded via a linking group.

X includes, for example, a group represented by -X ² -X ¹ . X ¹ is a polymerizable functional group or a reactive functional group. ^X2 is a single bond or a divalent linking group.
The divalent linking group for X ² includes, for example, a divalent hydrocarbon group which may have a substituent, an etheric oxygen at the end of the divalent hydrocarbon group which may have a substituent A group containing an atom and a group containing an etheric oxygen atom between carbon atoms of a divalent hydrocarbon group which may have a substituent are exemplified.

The divalent hydrocarbon group includes, for example, an alkylene group, a cycloalkylene group, an arylene group, and a group consisting of a combination of two or more thereof.
Examples of the alkylene group include those similar to the alkylene group for R ³ . Examples of substituents that the alkylene group may have include a hydroxyl group, a cyano group, and a halogen atom.
The number of carbon atoms in the cycloalkylene group can be, for example, 6-8. Examples of substituents that the cycloalkylene group may have include an alkyl group, a hydroxyl group, a cyano group, and a halogen atom.
Arylene groups include, for example, phenylene groups, naphthylene groups, phenanthrylene groups, anthrylene groups, and 4,4'-biphenyl-diyl groups. Examples of substituents that the arylene group may have include an alkyl group, a hydroxyl group, a cyano group, and a halogen atom.

^X2 preferably has a hydroxyl group as a substituent. If ^X2 has a hydroxyl group, the cured product using the compound (2) tends to be more excellent in heat resistance and mechanical strength. This is probably because the presence of hydroxyl groups provides an intermolecular force due to hydrogen bonding, resulting in an increase in molecular cohesion. In addition, this hydrogen bond can contribute to the improvement of adhesion to inorganic or organic materials such as glass and polyester (for example, films and lenses).

Specific examples of X include a glycidyl group, —[O—Ph—C(CH ₃ ) ₂ —Ph—O—CH ₂ —CH(OH)—CH ₂ ] _n —O—Ph—C(CH ₃ ) ₂ -Ph-O-Y ¹ , (meth)acryloyl group, 2-hydroxy-3-(meth)acryloyloxypropyl group (-CH ₂ -C(OH)-CH ₂ -O-C(=O)- C(R)=CH ₂ ), -[O-Ph-C(CH ₃ ) ₂ -Ph-O-CH ₂ -CH(OH)-CH ₂ ] _n -O-C(=O)-C(R )=CH ₂ , a trimellitic anhydride group (the following formula (X-1)), and an amino group. Here, Ph is a phenylene group. Y ¹ is a glycidyl group. R is a hydrogen atom or a methyl group.

Examples of the method for producing compound (2) include a method including the following step C.
Step C: A step of adding X (a monovalent group containing a polymerizable functional group or a reactive functional group) to the hydroxyl group of compound (1).

Step C can be carried out using known methods, depending on the structure of X.
For example, when X is a glycidyl group, a method of reacting the hydroxyl group of compound (1) with epihalohydrin (eg, epichlorohydrin) (hereinafter also referred to as "method 1") can be used.

X is -[O-Ph-C(CH ₃ ) ₂ -Ph-O-CH ₂ -CH(OH)-CH ₂ ] _n -O-Ph-C(CH ₃ ) ₂ -Ph-O-Y ¹ In this case, in Method 1, instead of epihalohydrin, a bisphenol A type epoxy compound may be reacted.

When X is a (meth)acryloyl group, a method of reacting the hydroxyl group of compound (1) with (meth)acrylic acid, (meth)acrylic anhydride or (meth)acrylic acid halide (hereinafter referred to as "Method 2" Also described.).

When X is a 2-(meth)acryloyloxy-2-hydroxyethyl group, after obtaining a compound in which X is a glycidyl group by the above method 1, the glycidyl group of the compound is added with (meth)acrylic acid, (meth) ) a method of reacting acrylic anhydride or (meth)acrylic acid halide (hereinafter also referred to as “Method 3”).

When X is -[O-Ph-C(CH ₃ ) ₂ -Ph-O-CH ₂ -CH(OH)-CH ₂ ] _n -O-C(=O)-C(R)=CH ₂ , In method 3, instead of obtaining compounds where X is a glycidyl group, X is -[O-Ph-C(CH ₃ ) ₂ -Ph-O-CH ₂ -CH(OH)-CH ₂ ] _n -O- A compound that is Ph--C(CH ₃ ) ₂ --Ph--O--Y ¹ should be obtained.

When X is a trimellitic anhydride group, a method of reacting the hydroxyl group of compound (1) with trimellitic anhydride or trimellitic anhydride halide (hereinafter also referred to as "method 4") can be mentioned.

In method 1, the molar ratio of epihalohydrin to the hydroxyl group of compound (1) (hydroxyl group/epihalohydrin ratio) is not particularly limited. The molar ratio (hydroxyl group/epihalohydrin ratio) may be the same molar ratio as when producing bisphenol A type epoxy resin, which is the most common epoxy resin, from bisphenol A and epichlorohydrin.

The hydroxyl group/epichlorohydrin ratio is preferably 0.02 to 0.33, more preferably 0.10 to 0.20.
When a large amount of epichlorohydrin is used with respect to 1 mol of hydroxyl groups in compound (1) (when the hydroxyl group/epichlorohydrin ratio is small), a compound in which hydroxyl groups are glycidyl-etherified is obtained as the main component. As this molar ratio is increased, the glycidyl-etherified epoxy group attached to the hydroxyl group may react with other hydroxyl groups to increase the molecular weight.

Since the compound (2) described above has a skeleton similar to that of the compound (1), it can exhibit a high refractive index.
Compound (2) also has one or more polymerizable functional groups or reactive functional groups. Therefore, the compound (2) can be polymerized by itself to form a polymer, or can be reacted with a curing agent (a cross-linking agent, a polymerization initiator, etc.) to form a cured product. A polymer or a cured product obtained using the compound (2) can express a high refractive index because it has a structural unit based on the compound (2).

Among compounds (2), compounds having an epoxy group as a polymerizable functional group or a reactive functional group can be used, for example, as constituents of curable compositions and epoxy adhesives.
For example, the compound may be added with an epoxy curing agent (e.g., amines, acid anhydrides, phenolic resins), optionally curing accelerators such as triphenylphosphines and imidazoles, glass powder, glass beads, and other transparent polymer particles. It can be used as an epoxy-based adhesive by adding an inorganic or organic filler such as an antioxidant, an antioxidant, and other additives. This epoxy adhesive can form an adhesive layer exhibiting a high refractive index.
For example, the compound can be used as a curable composition by adding a cross-linking agent having two or more functional groups capable of reacting with an epoxy group and, if necessary, other additives.

Among compounds (2), compounds having a (meth)acryloyl group as a polymerizable functional group or a reactive functional group can be used, for example, as a constituent component of a curable composition. A curable composition obtained by adding a polymerization initiator (photopolymerization initiator, thermal polymerization initiator, etc.) to the compound, and optionally a solvent, a coloring agent, an inorganic filler, an organic filler, an antioxidant, and other additives. can be cured by light or heat to obtain a cured product.
The resulting cured product contains a polymer having structural units based on compound (2). Also, it has a high refractive index. Therefore, the polymer is useful as an optical member.

Examples of optical members include microlenses for CMOS image sensors and index matching materials for touch panels. In addition to optical members, it can also be applied to liquid crystal, organic EL, electronic paper, filters, black matrix, and the like.

Among compounds (2), compounds having an acid anhydride group as a polymerizable functional group or a reactive functional group can be used, for example, as raw materials for polyimide. A polyimide can be obtained by reacting the compound with a diamine component. The resulting polyimide exhibits heat resistance, transparency, and a high refractive index, and can be used for film substrates such as touch panels, flexible printed circuit boards, and the like.

Examples of diamine components include 1,3-phenylenediamine, 4,4′-diaminodiphenyl ether, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, diamine compounds, diethylene glycol bis(3-amino propyl) ether, 9,9′-bis(4-aminophenyl)fluorene.

The present invention will be specifically described below with reference to examples, but the present invention is not limited by the following description. In the following, "%" indicates "% by mass" unless otherwise specified.

〔Measuring method〕
<NMR measurement>
A 7.7% d-dimethylsulfoxide (DMSO) solution was prepared for the obtained compound, and ¹ H-NMR and ¹³ C-NMR were measured. Tetramethylsilane was used as an internal standard.
Equipment used: ECZ-500R manufactured by JEOL RESONANCE

<FD-MS (field desorption mass spectrometry)>
A 0.2% tetrahydrofuran (THF) solution was prepared for the resulting compound, and FD-MS was measured under the conditions of an ion source FD+ and a mass range of 60-1600.
Equipment used: JMS-T200GC manufactured by JEOL Ltd.

<GPC>
A 1% THF solution was prepared for the resulting compound and subjected to GPC measurement.
Equipment used: HLC8320GPC manufactured by Tosoh Corporation
Column: TSKgel G3000HXL+G2000HXL+G2000HXL

<Refractive index>
Three concentrations of N-methylpyrrolidone solutions were prepared for the resulting compound. The refractive index of D line (wavelength 589 nm) at 26.5° C. was measured with a refractometer for each solution.
The concentrations of these three types are plotted on the horizontal axis and the respective refractive indices are plotted on the vertical axis. The refractive index at a concentration of 100% was calculated from the approximated curve of the least-squares method, and the calculated value was defined as the refractive index.
Equipment used: Atago Abbe refractometer DR-2M

[Example 1]
9.11 g (0.05 mol) of 4-biphenylaldehyde, 72.09 g (0.50 mol) of β-naphthol, and cyclopentylmethyl as a reaction solvent were placed in a 200 mL three-necked flask equipped with a stirrer, thermometer, and arene condenser. 72.09 g of ether was added and stirred. The temperature of the reaction solution was raised to 30° C. by heating, and 4-biphenylaldehyde and β-naphthol were dissolved in cyclopentylmethyl ether by continuing stirring. 0.78 g (0.0075 mol) of 35% hydrochloric acid was added thereto, and after heating the reaction solution to 55°C, stirring was continued for 3 hours while maintaining the temperature at 55°C, and then the reaction solution was cooled to 25°C. bottom. A white powder precipitated in the reaction solution was subjected to suction filtration using a Nutsche and a suction bottle. At this time, ADVANTEC 5C was used as the filter paper. The powder obtained here was washed with 32.3 g of cyclopentyl methyl ether on a Nutsche, and then washed with 36.04 g of ion-exchanged water three times. Drying in a vacuum dryer gave 18.51 g of white powder (81.8% of theoretical yield).

The obtained white powder was analyzed by ¹ H-NMR, ¹³ C-NMR, and FD-MS to obtain the desired product (1-di(2-hydroxy-3-naphthyl)methyl-4-phenylbenzene) represented by the following formula (11). It was confirmed that The physicochemical properties of the obtained white powder were as follows. GPC confirmed that the purity was 97.8%.

Mass spectrum: (m/z) 452.
¹ H-NMR: (500 MHz, DMSO-d ₆ ): δ 7.13 (s, 1H), 7.13 (d, J = 8.0 Hz, 2H), 7.17-7.21 (m, 4H ), 7.24 (ddd, J = 8.6Hz, 6.8Hz, 1.5Hz, 2H), 7.30 (tt, J = 7.4Hz, 1.4Hz, 1H), 7.42 (t, J = 7.8Hz, 2H), 7.49 (d, J = 8.7Hz, 2H), 7.62 (dd, J = 8.4Hz, 1.2Hz, 2H), 7.71 (d, J = 8.8Hz, 2H), 7.74 (dd, J = 8.1Hz, 1.4Hz, 2H), 8.22 (d, J = 8.7Hz, 2H), 9.85 (s, 2H) .
¹³ H-NMR: (500 MHz, DMSO-d ₆ ): δ 41.2, 119.0, 120.3, 122.2, 124.0, 125.9 and 126.0 (a pair of s), 126 .4, 127.0, 128.4, 128.6 and 128.7 (a pair of s), 128.8 and 128.9 (a pair of s), 134.3, 136.9, 140.4 , 143.7, 152.7.

Also, the filtrate in the suction filtration was transferred to a separating funnel and washed three times with 50.00 g of ion-exchanged water. After the water-washed filtrate was put into an eggplant-shaped flask, 58.66 g of cyclopentyl methyl ether was recovered by vacuum distillation at -0.0267 MPa while heating the eggplant-shaped flask with a hot water bath. The recovery rate with respect to the total amount of cyclopentyl methyl ether used was 48.6%. The recovery rate of cyclopentyl methyl ether can be further increased by increasing the cooling capacity of the condenser used during vacuum distillation.

[Comparative Example 1]
14.42 g (0.08 mol) of 9-fluorenone, 88.09 g (0.80 mol) of resorcin, and 14.0 g of ion-exchanged water as a reaction solvent were placed in a 200 mL three-necked flask equipped with a stirrer, a thermometer, and an arene condenser. 42 g was added and stirring was started. 7.45 g (0.037 mol) of dodecyl mercaptan was added thereto, and when the temperature of the reaction solution reached 55° C., 24.58 g (0.24 mol) of 35% hydrochloric acid was added. As the temperature was further increased, reflux started at an internal temperature of 116°C. 40.00 g of ion-exchanged water was injected 4 hours after the start of reflux. Further, the flask was cooled to bring the temperature of the reaction solution to 25°C. This reaction solution was transferred to an analysis funnel and extracted twice with 144.2 g of cyclopentyl methyl ether, and the two ether layers were collectively transferred to a separating funnel. This ether layer was washed twice with 173.0 g of ion-exchanged water, and the washed ether solution was distilled under reduced pressure to remove the ether, thereby obtaining 80.61 g of slurry. 40.3 g of isopropyl alcohol was added to this slurry and refluxed to dissolve the slurry. The powder precipitated by cooling was separated by suction filtration (filter paper: ADVANTEC 5C) using a Nutsche and a suction bottle to obtain 52.37 g of pale yellow powdery crude product. 10.00 g of this crude product was dissolved again in 22.00 g of isopropyl alcohol, refluxed once, and slowly cooled to room temperature. The precipitate was isolated by suction filtration (filter paper: ADVANTEC5C) and washed twice with 22.00 g of deionized water on a Nutsche. By drying under reduced pressure, 7.34 g of a white powdery purified product was obtained.

The resulting white powder was analyzed by ¹ H-NMR, ¹³ C-NMR, and FD-MS to identify the desired product (spiro[fluorene 9,9′-(2′,7′-dihydroxyxanthene)] represented by the following formula (12). ). The physicochemical properties of the obtained white powder were as follows. Moreover, it was confirmed by GPC that the purity was 97.3%.

Mass spectrum: (m/z) 364.
¹ H-NMR: (500 MHz, DMSO-d ₆ ): δ 5.85 (s, 1H), 6.13 (dd, J = 8.3 Hz, 2.4 Hz, 2H), 6.30 (d, J = 2.5Hz, 2H), 6.49 (d, J = 8.3Hz, 2H), 7.05 (d, J = 8.1Hz, 2H), 7.30 (tt, J = 7.4Hz, 1.4 Hz, 1 H), 7.41 (t, J = 7.7 Hz, 2 H), 7.51 (d, J = 8.3 Hz, 2 H), 7.61 (dd, J = 8.4 Hz, 1 .2 Hz, 2 H), 8.90-9.30 (a pair of br s, 4 H).
¹³ H-NMR: (500 MHz, DMSO-d ₆ ): δ 41.2, 102.5, 105.5, 121.3, 126.2, 126.5, 129.0, 129.5, 130.2 , 137.2, 140.3, 145.0, 155.5, 156.4.

Table 1 shows the refractive index of the compounds obtained in Example 1 and Comparative Example 1, and the concentration and refractive index of the solution used for measuring the refractive index.

The compound of Example 1 had a higher refractive index than the compound of Comparative Example 1.

According to the present invention, a compound capable of exhibiting a high refractive index and its use can be provided.

Claims (9)

1. A compound represented by the following formula (1).
   

   

   In formula (1), R ¹ is a hydrogen atom or an aryl group,
   R ² is a divalent group containing at least two benzene rings, two R ² may be the same or different,
   a and b are each independently an integer of 0 to 6,
   R ³ is an alkylene group, and when (a + b) is 2 or more, (a + b) R ³ may be the same or different,
   c and d are each independently an integer of 1 to 10,
   e is an integer from 0 to 5, f is an integer from 0 to 4,
   R ⁴ is a substituent, and when (e+f) is 2 or more, (e+f) R ^4s may be the same or different.
2. A compound represented by the following formula (2).
   

   

   In formula (2), R ¹ is a hydrogen atom or an aryl group,
   R ² is a divalent group containing at least two benzene rings, two R ² may be the same or different,
   a and b are each independently an integer of 0 to 6,
   R ³ is an alkylene group, and when (a + b) is 2 or more, (a + b) R ³ may be the same or different,
   c and d are each independently an integer of 1 to 10,
   X is a monovalent group containing a polymerizable functional group or a reactive functional group, or a hydrogen atom, (c + d) X may be the same or different, and at least one of (c + d) X is the monovalent group,
   e is an integer from 0 to 5, f is an integer from 0 to 4,
   R ⁴ is a substituent, and when (e+f) is 2 or more, (e+f) R ^4s may be the same or different.
3. A resin having a structural unit based on the compound according to claim 1.
4. The resin according to claim 3, which is a polycarbonate resin.
5. The resin according to claim 3, which is a polyester resin.
6. A curable composition containing the compound according to claim 2.
7. A cured product of the curable composition according to claim 6.
8. An optical member containing the resin according to any one of claims 3 to 5.
9. An optical member containing the cured product according to claim 7.