Polyester-based resin, its production method, and its application

Abstract

To provide a polyester-based resin which has a high refractive index and can reduce hue such as yellow.SOLUTION: A polyester resin is prepared by combining a dicarboxylic acid unit (A) containing at least one selected from the group consisting of a specific aromatic dicarboxylic acid unit (A1), a specific fluorenedicarboxylic acid unit (A2) and a specific alicyclic dicarboxylic acid unit (A3), and a diol unit (B) including a long chain aliphatic diol unit (B1) represented by the following formula (4) (A2 represents an alkylene group having 5 or more carbon atoms, and n2 represents an integer of 1 or more) and a specific diol unit.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a polyester resin containing a specific diol unit and a specific dicarboxylic acid unit, and a method for producing the same and uses thereof. [Background technology]

[0002] Polyester resins, which contain aromatic units as structural units, have high refractive indices and glass transition temperatures, and are therefore used as optical materials with high refractive indices and excellent heat resistance. In particular, in recent years, in the fields of light guides such as light guide plates and optical fibers, and optical lenses such as lenses for augmented reality (AR) or virtual reality (VR), in addition to a high refractive index, optical properties such as color tone and birefringence are required, and a highly satisfactory balance of mechanical properties, heat resistance, and moldability is also required.

[0003] Japanese Patent Laid-Open Publication No. 2003-306532 (Patent Document 1) discloses a polyester resin in which the glycol components are a 9,9-bis-(4-hydroxyethoxyphenyl)-fluorene component and an aliphatic glycol component having 2 to 4 carbon atoms, the 9,9-bis-(4-hydroxyethoxyphenyl)-fluorene component accounts for 10 to 60 mol % of the total glycol components, and the modified polyester resin is substantially free of germanium compounds.

[0004] WO2015 / 163323 pamphlet (Patent Document 2) discloses a polyester resin that mainly contains diol structural units and dicarboxylic acid structural units, in which 10 to 84 mol % of the diol structural units are structural units derived from ethylene glycol, 16 to 90 mol % of the diol structural units are structural units derived from neopentyl glycol, and 50 to 100 mol % of the dicarboxylic acid structural units are units derived from naphthalenedicarboxylic acid.

[0005] Japanese Patent Laid-Open Publication No. 2006-335974 (Patent Document 3) discloses a polyester resin composition comprising a polyester polymer composed of a dicarboxylic acid compound and a dihydroxy compound, wherein the dicarboxylic acid compound is primarily naphthalenedicarboxylic acid and / or its ester-forming derivative, the dihydroxy compound includes a compound having a 9,9-bisphenylfluorene skeleton, the Abbe number of the d-line is 23 or less, the glass transition temperature is 130°C or more, and the polyester resin composition includes at least one type of phosphoric acid compound and / or phosphorous acid compound. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-306532 [Patent Document 2] WO2015 / 163323 Brochure [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-335974 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when an aromatic ring is introduced to form a bulky structure in order to improve the refractive index, coloration (e.g., yellowing) tends to occur more easily and the color tone tends to deteriorate, so there is a trade-off between a high refractive index and reduced color such as yellowing (high colorless transparency), and it is difficult to achieve both. Therefore, even the polyester resins of Patent Documents 1 to 3 are unable to achieve both a high refractive index and reduced color.

[0008] Therefore, an object of the present disclosure is to provide a polyester resin that has a high refractive index and can reduce color such as yellowishness, as well as a production method and uses thereof. [Means for solving the problem]

[0009] As a result of intensive research to achieve the above object, the present inventors have found that a polyester resin having a high refractive index and capable of reducing color such as yellowness can be provided by combining dicarboxylic acid units (A) containing at least one selected from the group consisting of specific aromatic dicarboxylic acid units (A1), specific fluorenedicarboxylic acid units (A2), and specific alicyclic dicarboxylic acid units (A3) with diol units (B) containing specific long-chain aliphatic diol units (B1) and specific fluorenediol units (B2), and have completed the present invention (or the present disclosure).

[0010] That is, the present disclosure includes the following aspects.

[0011] Aspect [1]: A polyester resin containing a dicarboxylic acid unit (A) and a diol unit (B), The dicarboxylic acid unit (A) is represented by the following formula (1):

[0012] [ka]

[0013] (In the formula, Z 1 indicates an arene ring, R 1 represents a substituent, and m1 represents an integer of 0 or more.

[0014] an aromatic dicarboxylic acid unit (A1) represented by the following formula (2):

[0015] [ka]

[0016] (In the formula, A 1a and A 1b each independently represents an alkylene group, R 2 represents a substituent, and m2 represents an integer of 0 to 8.

[0017] and a fluorenedicarboxylic acid unit (A2) represented by the following formula (3):

[0018] [ka]

[0019] (In the formula, Z 2 represents an aliphatic hydrocarbon ring, R 3 represents a substituent, and m3 represents an integer of 0 or more.

[0020] and (A3) contains at least one dicarboxylic acid unit selected from the group consisting of alicyclic dicarboxylic acid units represented by The diol unit (B) is represented by the following formula (4):

[0021] [ka]

[0022] (In the formula, A 2 represents an alkylene group having 5 or more carbon atoms, and n2 represents an integer of 1 or more.

[0023] and a long-chain aliphatic diol unit (B1) represented by the formula: The following formula (5)

[0024] [ka]

[0025] (In the formula, Z 3a and Z 3b each independently represents an arene ring, A 3a and A 3b each independently represents an alkylene group; n3a and n3b ​​each independently represent an integer of 0 or more; R 4a and R 4b each independently represents a substituent, m4a and m4b each independently represents an integer of 0 or more, R 5 represents a substituent, and m5 represents an integer of 0 to 8.

[0026] fluorene-diol unit (B2) represented by the following formula (6):

[0027] [ka]

[0028] (In the formula, X 1 represents a direct bond or a linking group, Z 4a and Z 4b each independently represents an arene ring, A 4a and A 4b each independently represents an alkylene group; n4a and n4b each independently represent an integer of 0 or more; R 6a and R 6b each independently represents a substituent, and m6a and m6b each independently represent an integer of 0 or more.

[0029] and an aromatic diol unit (B3) represented by the following formula (7):

[0030] [ka]

[0031] (In the formula, X 2 represents a direct bond or a linking group, Z 5a and Z 5b each independently represents an aliphatic hydrocarbon ring, A 5a and A 5b each independently represents an alkylene group; n5a and n5b each independently represent an integer of 0 or more; R 7a and R 7b each independently represents a substituent, and m7a and m7b each independently represent an integer of 0 or more.

[0032] and at least one diol unit selected from the group consisting of alicyclic diol units (B4) represented by the following formula:

[0033] Aspect [2]: The diol unit (B) is represented by the following formula (8):

[0034] [ka]

[0035] (In the formula, A 6 represents an alkylene group having 4 or less carbon atoms, and n6 represents an integer of 1 or more.

[0036] The polyester resin according to the above aspect [1], further comprising a short-chain aliphatic diol unit (B5) represented by the following formula:

[0037] Aspect [3]: In the formula (4), A 2 The polyester resin according to the above aspect [1] or [2], wherein represents an alkylene group having 5 or more carbon atoms in the main chain, and n2 is 1.

[0038] Aspect [4]: ​​The dicarboxylic acid unit (A) contains the aromatic dicarboxylic acid unit (A1), and Z in the formula (1) 1 The polyester resin according to any one of the above aspects [1] to [3], wherein represents a fused polycyclic arene ring.

[0039] Aspect [5]: The diol unit (B) includes the short-chain aliphatic diol unit (B5), the molar ratio of the long-chain aliphatic diol units (B1) to the total amount of the fluorenediol units (B2), the aromatic diol units (B3) and the alicyclic diol units (B4) is (B1) / (B2) [(B3)+(B4)]=70 / 30 to 5 / 95; The polyester-based resin according to any one of the above aspects [2] to [4], wherein the molar ratio of the long-chain aliphatic diol units (B1) to the short-chain aliphatic diol units (B5) is (B1) / (B5)=50 / 50 to 3 / 97.

[0040] Aspect [6]: Chromaticity b * The polyester resin according to any one of the above aspects [1] to [5], wherein the absolute value of is 2.4 or less.

[0041] Aspect [7]: A method for producing a polyester resin according to any one of aspects [1] to [6], by polymerizing a dicarboxylic acid component (a) corresponding to the dicarboxylic acid unit (A) and a diol component (b) corresponding to the diol unit (B).

[0042] Aspect [8]: A molded article comprising the polyester resin according to any one of aspects [1] to [6].

[0043] Aspect [9]: The molded article according to aspect [8], which is an optical element.

[0044] Aspect

[10] : The molded article according to aspect [8] or [9], which is a light guide.

[0045] Aspect

[11] : In a polyester resin containing a dicarboxylic acid unit (A) and a diol unit (B), The diol unit (B) may be represented by the following formula (4):

[0046] [ka]

[0047] (In the formula, A 2 represents an alkylene group having 5 or more carbon atoms, and n2 represents an integer of 1 or more.

[0048] A long-chain aliphatic diol unit (B1) represented by the formula: The chromaticity b of the polyester resin * A method for reducing the absolute value of

[0049] In addition, the present disclosure may achieve the following secondary objectives (solve the problems).

[0050] Another object of the present disclosure is to provide a polyester resin that can achieve a high refractive index, an excellent color tone with reduced color, and high heat resistance, as well as a production method and uses thereof.

[0051] In this specification and claims, the number of carbon atoms in a substituent or the like is expressed as C1, C6, C 10 For example, "C1 alkyl group" means an alkyl group with 1 carbon atom, and "C 6-10 The term "aryl group" refers to an aryl group having 6 to 10 carbon atoms.

[0052] In the present specification and claims, the term "independently" means that two components are independent of each other, for example, an alkylene group A 1a and A 1b In this case, A 1a and A 1b and do not necessarily have to be the same alkylene group, but may be different alkylene groups.

[0053] In addition, in this specification and claims, the main chain of an alkylene group means a linear alkylene skeleton, and in the case of a linear alkylene group, it means the linear alkylene group itself, and in the case of a branched alkylene group, it means the linear alkylene skeleton excluding the branched alkyl group (the linear alkylene group directly bonded to two oxygen atoms in a diol unit).

[0054] Furthermore, in this specification and claims, when a numerical range is indicated using "X to Y", the extreme numerical values ​​X and Y may be included. [Effects of the Invention]

[0055] According to the present disclosure, a polyester resin can be provided that has a high refractive index and can reduce color tinge such as yellowish color. [Brief explanation of the drawings]

[0056] [Figure 1] FIG. 1 is a graph showing the relationship between the proportion (composition ratio) of long-chain aliphatic diol units (B1) in the polyester resins obtained in the examples and the chromaticity b*. DETAILED DESCRIPTION OF THE INVENTION

[0057] [Polyester resin] The polyester resin of the present disclosure tends to have a high refractive index and a reduced yellowish tint, thereby improving color tone, by combining dicarboxylic acid units (A) containing at least one dicarboxylic acid unit selected from the group consisting of specific aromatic dicarboxylic acid units (A1), specific fluorenedicarboxylic acid units (A2), and alicyclic dicarboxylic acid units (A3) with specific long-chain aliphatic diol units (B1) and diol units (B) containing specific diol units. Furthermore, the polyester resin of the present disclosure tends to have improved heat resistance without impairing moldability, because the glass transition temperature can be adjusted within an appropriate range by selecting the type and / or amount of the long-chain aliphatic diol units (B1).

[0058] (A) Dicarboxylic acid unit The polyester resin of the present disclosure contains, as the dicarboxylic acid unit (A), at least one dicarboxylic acid unit selected from the group consisting of the aromatic dicarboxylic acid unit (A1) represented by the formula (1), the fluorenedicarboxylic acid unit (A2) represented by the formula (2), and the alicyclic dicarboxylic acid unit (A3).

[0059] (A1) Aromatic dicarboxylic acid unit represented by formula (1) In the formula (1), Z 1Examples of the aromatic hydrocarbon ring (arene ring) represented by the formula (I) include monocyclic arene rings such as a benzene ring, polycyclic arene rings, etc. Examples of the polycyclic arene ring include fused polycyclic arene rings (fused polycyclic aromatic hydrocarbon rings), and ring-assembled arene rings (ring-assembled polycyclic aromatic hydrocarbon rings).

[0060] The fused polycyclic arene ring includes fused bicyclic arene rings, fused tricyclic arene rings, and other fused bicyclic to tetracyclic arene rings. The fused bicyclic arene ring includes fused bicyclic C rings such as naphthalene rings and indene rings. 8-20 Examples of the fused tricyclic arene ring include fused tricyclic C arenes such as acenaphthylene ring, fluorene ring, phenalene ring, anthracene ring, and phenanthrene ring. 14-20 The fused tetracyclic arene rings include fused tetracyclic C arenes such as pyrene rings and naphthacene rings. 16-22 arene rings.

[0061] 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.

[0062] 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).

[0063] Among these arene rings, ring Z 1 Examples include fused polycyclic C rings such as benzene rings and naphthalene rings. 10-14 C such as arene ring and biphenyl ring 12-18 A biarene ring is preferred, and a C ring such as a benzene ring or a naphthalene ring is preferred. 6-12Further, from the viewpoint of facilitating improvements in refractive index, color tone, and heat resistance, fused polycyclic arene rings are preferred, and naphthalene rings are particularly preferred.

[0064] R 1 Examples of the substituent represented by the formula (non-reactive substituent or non-polymerizable substituent) include a halogen atom, a hydrocarbon group, an alkoxy group, a cycloalkyloxy group, an aryloxy group, an aralkyloxy group, an alkylthio group, a cycloalkylthio group, an arylthio group, an aralkylthio group, an acyl group, a mono- or di-substituted amino group, a nitro group, and a cyano group.

[0065] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0066] The hydrocarbon group includes a straight-chain or branched-chain alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and the like.

[0067] Examples of alkyl groups (linear or branched chain alkyl groups) include C groups such as methyl, ethyl, propyl, isopropyl, n-butyl, and t-butyl groups. 1-10 Examples of cycloalkyl groups include C alkyl groups such as cyclopentyl and cyclohexyl groups. 5-10 Examples of the aryl group include a C cycloalkyl group, such as a phenyl group, a biphenylyl group, and a naphthyl group. 6-12 Aryl groups; mono- or tri-C such as methylphenyl (or tolyl), dimethylphenyl (or xylyl) groups 1-4 Examples of aralkyl groups include C alkyl-phenyl groups, benzyl groups, phenethyl groups, etc. 6-10 Aryl-C 1-4 Examples of suitable alkyl groups include:

[0068] Examples of alkoxy groups (linear or branched alkoxy groups) include C groups such as methoxy, ethoxy, propoxy, n-butoxy, and t-butoxy. 1-10 Examples include alkoxy groups.

[0069] Acyl groups include C groups such as acetyl groups. 1-6 Examples of the substituted amino group include mono- or di-C groups such as dimethylamino groups. 1-4 Alkylamino group; bis(C) such as diacetylamino group 1-4 alkyl-carbonyl)amino groups.

[0070] Examples of cycloalkyloxy groups include C cyclohexyloxy groups. 5-10 Examples include cycloalkyloxy groups.

[0071] The aryloxy group is a C group such as a phenoxy group. 6-10 Examples thereof include an aryloxy group.

[0072] Aralkyloxy groups include C aryloxy groups such as benzyloxy groups. 6-10 Aryl-C 1-4 Examples thereof include an alkyloxy group.

[0073] Examples of alkylthio groups include C alkylthio groups such as methylthio groups, ethylthio groups, propylthio groups, n-butylthio groups, and t-butylthio groups. 1-10 Examples include an alkylthio group.

[0074] Examples of cycloalkylthio groups include C cyclohexylthio groups. 5-10 Examples include a cycloalkylthio group.

[0075] The arylthio group includes C thiophenoxy group (phenylthio group) and the like. 6-10 An example is an arylthio group.

[0076] Aralkylthio groups include C aryl groups such as benzylthio groups. 6-10 Aryl-C 1-4 Examples include an alkylthio group.

[0077] Acyl groups include C groups such as acetyl groups. 1-6Examples include alkyl-carbonyl groups.

[0078] 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 bis(C 1-4 alkyl-carbonyl)amino groups.

[0079] Representative examples of these substituents include halogen atoms, hydrocarbon groups such as alkyl groups, cycloalkyl groups, and aralkyl groups, alkoxy groups, acyl groups, nitro groups, cyano groups, substituted amino groups, etc. These substituents may be contained alone or in combination of two or more.

[0080] Preferred substituents include an alkyl group, a cycloalkyl group, an aryl group, and an alkoxy group. The alkyl group is preferably a C 1-6 An alkyl group is preferred, and a cycloalkyl group is a C cyclohexyl group or the like. 5-8 The cycloalkyl group is preferred, and the aryl group is preferably a C aryl group such as a phenyl group or a naphthyl group. 6-14 An aryl group is preferred, and the alkoxy group is a C alkoxy group such as a methoxy group. 1-4 Alkoxy groups are preferred. Among them, alkyl groups are preferred, and C groups such as methyl groups are also preferred. 1-4 Alkyl groups are particularly preferred.

[0081] R 1 The number of substitutions m1 in the ring Z can be any integer greater than or equal to 0. 1 For example, m1 may be an integer of 0 to 8, but is preferably an integer of 0 to 6, an integer of 0 to 4, an integer of 0 to 3, an integer of 0 to 2, more preferably 0 or 1, and most preferably 0. When m1 is an integer of 2 or more, two or more substituents R 1 may be the same or different.

[0082] Examples of the aromatic dicarboxylic acid component (a1) corresponding to the aromatic dicarboxylic acid unit (A1) include a monocyclic aromatic dicarboxylic acid component, a condensed polycyclic aromatic dicarboxylic acid component, and a ring-assembled polycyclic aromatic dicarboxylic acid component.

[0083] Examples of the monocyclic aromatic dicarboxylic acid component include benzenedicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, or ester-forming derivatives thereof; C carboxylic acids such as 5-methylisophthalic acid; 1-4 Examples thereof include alkyl-benzenedicarboxylic acids or ester-forming derivatives thereof.

[0084] The condensed polycyclic aromatic dicarboxylic acid component may be a condensed polycyclic C such as naphthalenedicarboxylic acid or an ester-forming derivative thereof, such as 1,2-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, or 2,6-naphthalenedicarboxylic acid; anthracenedicarboxylic acid or an ester-forming derivative thereof; or phenanthrenedicarboxylic acid or an ester-forming derivative thereof. 10-24 arene-dicarboxylic acids or ester-forming derivatives thereof.

[0085] Examples of ring-assembled polycyclic aromatic dicarboxylic acid components include bi-C such as 2,2'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. 6-10 arene-dicarboxylic acids or ester-forming derivatives thereof.

[0086] Unless otherwise specified in the present specification and claims, the term "ester-forming derivative" refers to an alkyl ester (or lower alkyl ester), specifically, a C ester such as a methyl ester or an ethyl ester. 1-4 It means alkyl esters and the like; acid halides such as acid chlorides; and acid anhydrides.

[0087] These aromatic dicarboxylic acid units (A1) may be contained alone or in combination of two or more. A preferred aromatic dicarboxylic acid unit (A1) is a unit represented by the formula (1) above, wherein Z 1 C such as benzene ring, naphthalene ring 6-12 A dicarboxylic acid unit which is an arene ring, particularly a naphthalene ring, and in which m1 is 0; more preferably a 2,6-naphthalenedicarboxylic acid unit. The proportion of the aromatic dicarboxylic acid unit (A1) in the aromatic dicarboxylic acid unit (A1) can be selected, for example, from a range of about 10 to 100 mol %, preferably 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably 100 mol % in the following stepwise manner. When the proportion of the aromatic dicarboxylic acid unit (A1) is equal to or greater than the lower limit, the refractive index, color tone, and heat resistance tend to be improved.

[0088] (A2) Fluorenedicarboxylic acid unit represented by formula (2) In the formula (2), A 1a and A 1b Examples of the alkylene group (linear or branched alkylene group) represented by the formula (I) include C alkylene groups such as methylene group, ethylene group, propylene group (1,2-propanediyl group), trimethylene group, 1,2-butanediyl group, tetramethylene group, and 2-methylpropane-1,3-diyl group. 1-8 Alkylene group, etc. Alkylene group A 1a is an alkylene group A 1b These alkylene groups may be different from each other, but are preferably the same. These alkylene groups may be contained alone or in combination of two or more. Among these, C groups such as ethylene and propylene groups are preferred. 2-3 Alkylene groups are preferred, with ethylene groups being particularly preferred.

[0089] R 2 Examples of the substituent represented by the formula (non-reactive substituent or non-polymerizable substituent) include R 1 The substituents may be contained alone or in combination of two or more. Among the substituents, alkyl groups and aryl groups are preferred, and C groups such as methyl groups are also preferred. 1-4C such as alkyl group and phenyl group 6-12 Aryl groups are particularly preferred, C 6-10 An aryl group is more preferred.

[0090] R 2 The number of substitutions m2 can be selected, for example, from the range of integers from 0 to 8, preferably from integers from 0 to 6, from integers from 0 to 4, from integers from 0 to 3, from integers from 0 to 2, and more preferably from 0 or 2. In particular, 0 is most preferred from the viewpoint of facilitating improvement of color tone, and 2 is most preferred from the viewpoint of facilitating improvement of refractive index and heat resistance. When m2 is an integer of 2 or more, two or more substituents R 2 may be the same or different.

[0091] In addition, the group R 2 When the number of substitutions m2 is 2 or more, two or more groups R 2 The types of groups may be the same or different, and two or more groups R substituted on different benzene rings may be 2 The types of groups R may be the same or different. 2 The bonding positions (substitution positions) of are not particularly limited as long as they are the 1st to 8th positions of the fluorene ring, and examples thereof include the 2nd, 7th, and 2,7th positions of the fluorene ring, with the 2,7th positions being preferred.

[0092] Examples of the fluorenedicarboxylic acid component (a2) corresponding to the fluorenedicarboxylic acid unit (A2) include 9,9-bis(carboxy C) such as 9,9-bis(2-carboxyethyl)-fluorene and 9,9-bis(2-carboxypropyl)-fluorene. 2-6 alkyl)-fluorene; 9,9-bis(carboxy C) such as 9,9-bis(2-methoxycarbonylethyl)-2,7-diphenylfluorene 2-6 alkyl)-diarylfluorene; or ester-forming derivatives thereof.

[0093] These fluorenedicarboxylic acid units (A2) may be contained alone or in combination of two or more. A preferred fluorenedicarboxylic acid unit (A2) is a fluorenedicarboxylic acid unit represented by the formula (2): 1a and A 1b C 2-3 It is a dicarboxylic acid unit which is an alkylene group and m2 is 0. The proportion of the fluorenedicarboxylic acid units (A2) in the fluorenedicarboxylic acid units (A2) can be selected, for example, within a range of about 10 to 100 mol %, and is preferably 50 mol % or more, 70 mol % or more, 90 mol % or more, stepwise thereafter, and more preferably 100 mol %.

[0094] The ratio (molar ratio) of the aromatic dicarboxylic acid unit (A1) to the fluorenedicarboxylic acid unit (A2) may be 100 / 0 to 0 / 100, preferably 100 / 0 to 50 / 50, more preferably 100 / 0 to 70 / 30, and even more preferably 100 / 0 to 90 / 10, with only the aromatic dicarboxylic acid unit (A1) being most preferred. For applications requiring high heat resistance, the ratio (molar ratio) may be 99 / 1 to 50 / 50, preferably 95 / 5 to 60 / 40, more preferably 90 / 10 to 65 / 35, and even more preferably 80 / 20 to 70 / 30, since this facilitates the improvement of a high refractive index, excellent color tone, and high heat resistance. In particular, the ratio (molar ratio) of 100 / 0 to 95 / 5 is preferred for achieving an excellent balance between a high refractive index, excellent color tone, and high heat resistance. When the proportion of the aromatic dicarboxylic acid unit (A1) is high, the refractive index, color tone, and heat resistance tend to be improved.

[0095] (A3) Alicyclic dicarboxylic acid unit represented by formula (3) In the formula (3), Z 2 Examples of the aliphatic hydrocarbon ring represented by the formula include a cycloalkane ring and a bridged cycloalkane ring.

[0096] The cycloalkane ring is a mono-C ring such as a cyclopentane ring, a cyclohexane ring, or a cyclooctane ring. 5-10Examples of the bridged cycloalkane ring include bi- or tri-C such as norbornane ring (bicycloheptane ring), decalin ring (decahydronaphthalene ring), adamantane ring, and tricyclodecane ring. 6-14 Examples include a cycloalkane ring.

[0097] Among these aliphatic hydrocarbon rings, mono-C such as cyclohexane ring 5-8 Bi-C such as cycloalkane ring and decalin ring 6-10 A cycloalkane ring is preferred, and a mono C ring such as a cyclohexane ring is preferred. 5-8 Cycloalkane rings and decalin rings are more preferred, and mono C is preferred because it is easy to improve color tone. 5-8 A cycloalkane ring is more preferred, and a cyclohexane ring is most preferred.

[0098] R 3 The substituents (non-reactive or non-polymerizable substituents) represented by R, including preferred embodiments thereof, 1 R 3 The range of substitution number m3 and the preferred range of R 1 The number of substitutions m1 can be selected from the ranges described above.

[0099] Examples of the alicyclic dicarboxylic acid component (a3) ​​corresponding to the alicyclic dicarboxylic acid unit (A3) include C cyclohexanedicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid. 5-7 Examples thereof include cycloalkane-dicarboxylic acids or ester-forming derivatives thereof; decalin dicarboxylic acids such as 1,2-decalin dicarboxylic acid, 1,4-decalin dicarboxylic acid, 1,5-decalin dicarboxylic acid, 1,8-decalin dicarboxylic acid, 2,3-decalin dicarboxylic acid, and 2,6-decalin dicarboxylic acid, or ester-forming derivatives thereof.

[0100] The molar ratio of the aromatic dicarboxylic acid units (A1) to the alicyclic dicarboxylic acid units (A3) may be 100 / 0 to 0 / 100, preferably 100 / 0 to 50 / 50, more preferably 100 / 0 to 70 / 30, even more preferably 100 / 0 to 80 / 20, most preferably 100 / 0 to 90 / 10, and most preferably 100 / 0. A high ratio of the aromatic dicarboxylic acid units (A1) tends to improve the refractive index, color tone, and heat resistance.

[0101] (A4) Other dicarboxylic acid units The dicarboxylic acid unit (A) may further contain other dicarboxylic acid units (A4) as required. Examples of the other dicarboxylic acid units (A4) include aliphatic dicarboxylic acid units.

[0102] The aliphatic carboxylic acid components corresponding to the aliphatic dicarboxylic acid unit include C such as malonic acid, succinic acid, adipic acid, and sebacic acid. 1-20 Alkane-dicarboxylic acids or their ester-forming derivatives; C such as maleic acid and fumaric acid 2-10 Alkene-dicarboxylic acid or its ester-forming derivative, etc. These other dicarboxylic acid units may be contained alone or in combination of two or more kinds.

[0103] The proportion of the other dicarboxylic acid units (A4) may be 50 mol % or less of the total dicarboxylic acid units (A), and preferably 30 mol % or less, 10 mol % or less, and 5 mol % or less in the following stepwise manner. The dicarboxylic acid units (A) preferably do not substantially contain other dicarboxylic acid units (A4), and particularly preferably do not contain any other dicarboxylic acid units (A4).

[0104] The total amount of the aromatic dicarboxylic acid units (A1) and the fluorenedicarboxylic acid units (A2) in the total dicarboxylic acid units (A) may be, for example, 50 mol% or more, for example, 80 mol% or more, preferably 90 mol% or more, further preferably 95 mol% or more, more preferably 99 mol% or more, and most preferably 100 mol%. When the total amount is equal to or more than the lower limit, the refractive index, color tone, and heat resistance tend to be improved.

[0105] The total amount of the aromatic dicarboxylic acid units (A1), the fluorenedicarboxylic acid units (A2) and the alicyclic dicarboxylic acid units (A3) may be, for example, 50 mol% or more, for example, 80 mol% or more, preferably 90 mol% or more, further preferably 95 mol% or more, more preferably 99 mol% or more, and most preferably 100 mol% of all the dicarboxylic acid units (A). When the total amount is equal to or more than the lower limit, the refractive index, color tone and heat resistance tend to be improved.

[0106] The proportion of the aromatic dicarboxylic acid units (A1) in the total dicarboxylic acid units (A) may be, for example, 30 mol% or more, for example, 50 mol% or more, preferably 80 mol% or more, further preferably 90 mol% or more, more preferably 99 mol% or more, and most preferably 100 mol%. When the proportion of the aromatic dicarboxylic acid units (A1) is equal to or greater than the lower limit, the refractive index, color tone, and heat resistance tend to be improved.

[0107] Z in the formula (1) 1 The proportion of the aromatic dicarboxylic acid units (A1) in which each of the dicarboxylic acid units (A) is a fused polycyclic arene ring may be 30 mol % or more, for example, 50 mol % or more, preferably 80 mol % or more, further preferably 90 mol % or more, more preferably 99 mol % or more, and most preferably 100 mol % of the total dicarboxylic acid units (A). When the proportion of the aromatic dicarboxylic acid units (A1) is equal to or greater than the lower limit, the refractive index, color tone, and heat resistance tend to be improved.

[0108] The proportion of the fluorenedicarboxylic acid units (A2) in the total dicarboxylic acid units (A) may be, for example, 30 mol% or more, for example, 50 mol% or more, preferably 80 mol% or more, further preferably 90 mol% or more, more preferably 99 mol% or more, and most preferably 100 mol%. When the proportion of the fluorenedicarboxylic acid units (A2) is equal to or more than the lower limit, the refractive index, color tone, and heat resistance tend to be improved.

[0109] The proportion of the alicyclic dicarboxylic acid units (A3) in the total dicarboxylic acid units (A) may be, for example, 10 mol % or more, for example, 10 to 90 mol %, preferably 13 to 50 mol %, and more preferably 20 to 40 mol %. When the proportion of the alicyclic dicarboxylic acid units (A3) is within this range, the refractive index, color tone, and heat resistance tend to be improved.

[0110] (B) Diol unit The polyester-based resin of the present disclosure contains, as diol units (B), long-chain aliphatic diol units (B1) represented by formula (4) and at least one diol unit selected from the group consisting of fluorenediol units (B2) represented by formula (5), aromatic diol units (B3) represented by formula (6), and alicyclic diol units (B4) represented by formula (7). In particular, the polyester-based resin of the present disclosure contains long-chain aliphatic diol units (B1), which tends to reduce color hues such as yellowness and improve color tone. Furthermore, the polyester-based resin of the present disclosure tends to have improved refractive index and heat resistance when it contains fluorenediol units (B2).

[0111] (B1) A long-chain aliphatic diol unit represented by formula (4) In the formula (4), A 2 The alkylene group represented by the formula (I) is not particularly limited as long as it is an alkylene group (straight-chain or branched-chain alkylene group) having 5 or more carbon atoms, and examples thereof include a 2,2-dimethyl-1,3-propanediyl group (neopentyl group), a 2-methyl-1,4-butanediyl group, a 1,5-pentanediyl group, a 3-methyl-1,5-pentanediyl group, a 1,6-hexanediyl group, a 2-ethyl-1,6-hexanediyl group, a 1,7-heptanediyl group, a 2,4-dimethylpentanediyl group, a 1,8-octanediyl group, a 1,9-nonanediyl group, and a 1,10-decanediyl group.

[0112] Alkylene Group A 2 The number of carbon atoms may be 5 or more, for example, 5 to 20, preferably 5 to 12, further preferably 5 to 10, even more preferably 5 to 8, and most preferably 5 to 7.

[0113] Alkylene Group A 2 The number of carbon atoms in the main chain may be, for example, 3 or more, preferably 4 or more, and more preferably 5 or more, and is particularly preferably 3 to 15, 4 to 13, 5 to 12, 5 to 9, and 5 to 8 in the following stepwise order, and is more preferably 5 to 7, and most preferably 5 to 6, from the viewpoint of facilitating improvement in color tone and heat resistance.

[0114] Among such alkylene groups, C groups such as neopentyl, 1,5-pentanediyl, and 3-methyl-1,5-pentanediyl groups, which have 3 or more carbon atoms in the main chain, are 5-9 An alkylene group (an alkylene group having 5 to 9 carbon atoms) is preferred, and a C 5-8 An alkylene group having 5 or more carbon atoms in the main chain is more preferred. 5-7 An alkylene group is more preferred, and the C 5-6 Alkylene groups are most preferred.

[0115] The repeat number n2 may be an integer of 1 or more, for example, an integer of 1 to 10, and is preferably an integer of 1 to 4, an integer of 1 to 3, or 1 or 2, with 1 being particularly preferred. When n2 is an integer of 2 or more, two or more alkylene groups A 2 The types may be different, but are preferably the same.

[0116] Examples of the aliphatic diol component (b1) corresponding to the long-chain aliphatic diol unit (B1) include C 111, C 112, C 113, C 114, C 115, C 116, C 117, C 118, C 119 ... 5-20 Alkanediols: di- or deca-C such as dipentanediol and tripentanediol 5-12 Alkanediols and the like.

[0117] These long-chain aliphatic diol units (B1) may be contained alone or in combination of two or more. A preferred long-chain aliphatic diol unit (B1) is a long-chain aliphatic diol unit represented by the formula (4): 2 C has a main chain carbon number of 3 or more 5-9 a diol unit in which n2 is an alkylene group and n2 is 1; more preferably a diol unit in which the main chain has 4 or more carbon atoms, such as 1,5-pentanediol 5-7 The diol units are derived from alkanediol. The proportion of the preferred long-chain aliphatic diol units (B1) in the long-chain aliphatic diol units (B1) can be selected, for example, from a range of about 10 to 100 mol %, preferably 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably 100 mol % in the following stepwise manner. When the proportion of the preferred long-chain aliphatic diol units (B1) is equal to or greater than the lower limit, color tone such as reduced yellowness and heat resistance tend to be improved.

[0118] The proportion of the long-chain aliphatic diol units (B1) may be 1 mol% or more of the total diol units (B), and can be selected from a range of, for example, about 1 to 90 mol%, preferably 1 to 80 mol%, 3 to 70 mol%, 5 to 50 mol%, 8 to 30 mol%, 10 to 20 mol%, and most preferably 12 to 17 mol%. To facilitate the enhancement of a high refractive index, excellent color tone, and high heat resistance, the proportion may be 1 to 20 mol%, preferably 2 to 15 mol%, more preferably 3 to 10 mol%, more preferably 4 to 8 mol%, and most preferably 6 to 8 mol%, of the total diol units (B). In particular, to achieve an excellent balance between a high refractive index, excellent color tone, and high heat resistance, the proportion is 1 to 30 mol%, preferably 5 to 20 mol%, more preferably 6 to 15 mol%, and most preferably 10 to 14 mol% of the total diol units (B). When the proportion of the long-chain aliphatic diol unit (B1) is at least the lower limit, the color tone tends to be easily improved, and when it is at most the upper limit, the refractive index and heat resistance tend to be easily improved.

[0119] (B2) Fluorenediol unit represented by formula (5) In the formula (5), Z 3a and Z 3bAs the arene ring represented by Z 1 Ring Z 3a is the ring Z 3b Among the arene rings, ring Z may be different from ring Z, but is preferably the same. 3a and ring Z 3b As for C 6-12 An arene ring is preferred, a benzene ring, a naphthalene ring, or a biphenyl ring is more preferred, a benzene ring or a biphenyl ring is even more preferred, and a benzene ring is still more preferred.

[0120] A 3a and A 3b Examples of the alkylene group (linear or branched alkylene group) represented by the formula (I) include C alkylene groups such as ethylene group, propylene group, trimethylene group, 1,2-butanediyl group, and tetramethylene group. 2-6 These alkylene groups may be contained alone or in combination of two or more. 2-6 Alkylene groups are preferred, C 2-4 Alkylene groups are more preferred, and C groups such as ethylene groups and propylene groups are preferred. 2-3 Alkylene groups are more preferred, and ethylene groups are most preferred. 3a is an alkylene group A 3b may be different from, but are preferably the same.

[0121] The repeat numbers n3a and n3b ​​are each an integer of 0 or more, and can be selected, for example, from the range of integers 0 to 15. Preferably, they are the following stepwise integers: 0 to 10, 0 to 8, 0 to 6, 0 to 4, 0 to 2, and 0 to 1. Furthermore, when the repeat numbers n3a and n3b ​​are each an integer of 1 or more, polymerization reactivity is easily improved. Preferably, they are the following stepwise integers: 1 to 10, 1 to 8, 1 to 6, 1 to 4, 1 to 3, and 1 to 2, with 1 being the most preferred. When n3a and n3b ​​are each below the upper limit, heat resistance and refractive index tend to improve. Furthermore, the repeat number n3a may be the same as or different from the repeat number n3b. When n3a and n3b ​​are each an integer of 2 or more, two or more alkylene groups A 3a and A 3b The types may be the same or different.

[0122] In this specification and claims, the "repeating number (number of moles added)" may be an average value (arithmetic mean value, additive mean value) or an average number of moles added, and preferred embodiments may be the same as the above-mentioned preferred range of integers.

[0123] Ring Z 3a and ring Z 3b The group [-O-(A 3a O) n3a -] and the group [-O-(A 3b O) n3b The substitution position of the ether bond-containing group is not particularly limited. 3a , ring Z 3b It is sufficient to substitute them in the appropriate positions.

[0124] Ring Z 3a and ring Z 3b The group [-O-(A 3a O) n3a -] and the group [-O-(A 3b O) n3b -] is substituted at the ring Z 3a and ring Z 3bWhen is a benzene ring, it is preferably substituted at the 2-, 3- or 4-position, particularly the 3- or 4-position, and particularly the 4-position, of the phenyl group bonded to the 9-position of the fluorene ring.

[0125] Ring Z 3a and ring Z 3b The group [-O-(A 3a O) n3a -] and the group [-O-(A 3b O) n3b -] is substituted at the ring Z 3a and ring Z 3b 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 the 1,5-position, 2,6-position, or particularly 2,6-position be substituted with respect to this substitution position.

[0126] Ring Z 3a and ring Z 3b is a ring-assembled arene ring, the group [-O-(A 3a O) n3a -] and the group [-O-(A 3b O) n3b The substitution position of -] is not particularly limited, and may be substituted, for example, on the arene ring bonded to the 9-position of the fluorene ring or on the arene ring adjacent to this arene ring. For example, ring Z 3a and ring Z 3b When A is a biphenyl ring, the 3- or 4-position of the biphenyl ring, preferably the 3-position, may be bonded to the 9-position of the fluorene ring. When the 3-position of the biphenyl ring is bonded to the 9-position of the fluorene ring, the group [-O-(A 3a O) n3a -] and the group [-O-(A 3b O) n3b The substitution position of -] may be, for example, any of the 2-, 4-, 5-, 6-, 2'-, 3'-, and 4'-positions of the biphenyl ring, preferably the 6- or 4'-position, and particularly preferably the 6-position.

[0127] R 4a and R4b Examples of the substituent represented by the formula (non-reactive substituent or non-polymerizable substituent) include R 1 The substituents may be contained alone or in combination of two or more. Among these, alkyl groups are preferred, and C groups such as methyl groups are preferred. 1-4 Alkyl groups are particularly preferred. 4a is the substituent R 4b It may be the same as or different from.

[0128] The substitution numbers m4a and m4b are 3 and ring Z 3b Depending on the type of substituent R, m4a can be selected from integers of 0 or more, for example, integers of 0 to 4, preferably integers of 0 to 2, further preferably 0 or 1, and even more preferably 0. The number of substitutions m4a and m4b may be different from each other, but are preferably the same. When m4a and m4b are integers of 2 or more, two or more substituents R 4a and substituent R 4b The types may be the same or different.

[0129] Substituent R 4a and R 4b The substitution position of is not particularly limited, and 3a and ring Z 3b When is a benzene ring, the 2- and / or 6-positions, 3- and / or 5-positions of each phenyl group bonded to the 9-position of the fluorene ring are preferred, and the 3- and / or 5-positions are particularly preferred.

[0130] R 5 Examples of the substituent represented by the formula (non-reactive substituent or non-polymerizable substituent) include R 1 The substituents may be contained alone or in combination of two or more. Among the substituents, alkyl groups are preferred, and C groups such as methyl groups are preferred. 1-4 Alkyl groups are particularly preferred.

[0131] The number of substitutions m5 may be, for example, an integer of 0 to 8, but is preferably an integer of 0 to 6, an integer of 0 to 4, an integer of 0 to 3, an integer of 0 to 2, in the following stepwise order, more preferably 0 or 1, and most preferably 0. In addition, in the two benzene rings constituting the fluorene ring, the group R 5 The number of substitutions in each of the above may be different from each other, but is preferably the same.

[0132] In addition, the group R 5 When the number of substitutions m5 is 2 or more, two or more groups R 5 The types of groups may be the same or different, and two or more groups R substituted on different benzene rings may be 5 The types of groups R may be the same or different. 5 The bonding positions (substitution positions) of are not particularly limited as long as they are the 1st to 8th positions of the fluorene ring, and examples thereof include the 2nd, 7th, and 2,7th positions of the fluorene ring, with the 2,7th positions being preferred.

[0133] Examples of the fluorenediol component (b2) corresponding to the fluorenediol unit (B2) include 9,9-bis(hydroxyphenyl)fluorenes such as 9,9-bis(4-hydroxyphenyl)fluorene; 9,9-bis[(mono or di)C] such as 9,9-bis(4-hydroxy-3-methylphenyl)fluorene; 1-4 9,9-bis[hydroxy(mono to deca)C such as 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, 9,9-bis[4-(2-(2-hydroxyethoxy)ethoxy)phenyl]fluorene, and 9,9-bis[4-(2-hydroxypropoxy)phenyl]fluorene 2-4 9,9-bis[(mono or di)C alkoxy-phenyl]fluorene; 9,9-bis[4-(2-hydroxyethoxy)-3-methylphenyl]fluorene, etc. 1-4 Alkyl-hydroxy (mono or deca)C 2-4Alkoxy-phenyl]fluorene; 9,9-bis(hydroxynaphthyl)fluorenes such as 9,9-bis(6-hydroxy-2-naphthyl)fluorene and 9,9-bis(5-hydroxy-1-naphthyl)fluorene; 9,9-bis[hydroxy(mono to deca)C] such as 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]fluorene, 9,9-bis[5-(2-hydroxyethoxy)-1-naphthyl]fluorene, 9,9-bis[6-(2-(2-hydroxyethoxy)ethoxy)-2-naphthyl]fluorene, and 9,9-bis[6-(2-hydroxypropoxy)-2-naphthyl]fluorene 2-4 9,9-bis(C alkoxy-naphthyl)fluorene; 9,9-bis(4-hydroxy-3-phenylphenyl)fluorene, etc. 6-10 9,9-bis(aryl-hydroxyphenyl)fluorene; 9,9-bis(C 6-10 Aryl-hydroxy(mono or deca)C 2-4 alkoxyphenyl)fluorene and the like.

[0134] These fluorenediol units (B2) may be contained alone or in combination of two or more. A preferred fluorenediol unit (B2) is a fluorenediol unit represented by the formula (5) in which the ring Z 3a and ring Z 3b is a benzene ring, and A 3a and A 3b C 2-3 a diol unit in which n3a and n3b ​​are integers of 1 or more, and m4a, m4b, and m5 are 0; more preferably, a diol unit in which n3a and n3b ​​are integers of 1 or more, and m4a, m4b, and m5 are 0; 2-4The diol unit (B2) is a diol unit derived from [alkoxy-phenyl]fluorene. The proportion of the fluorenediol units (B2) can be selected, for example, from a range of about 10 to 100 mol % in the fluorenediol units (B2), and is preferably 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably 100 mol % in the following stepwise manner. When the proportion of the fluorenediol units (B2) is equal to or greater than the lower limit, the refractive index and heat resistance tend to be improved.

[0135] The molar ratio of the long-chain aliphatic diol unit (B1) to the fluorenediol unit (B2) can be selected from a range of about (B1) / (B2) = 99 / 1 to 1 / 99 (e.g., 90 / 10 to 1 / 99), for example, 70 / 30 to 5 / 95, preferably 60 / 40 to 10 / 90, more preferably 50 / 50 to 20 / 80, and more preferably 40 / 60 to 25 / 75. In particular, from the viewpoint of facilitating the improvement of a high refractive index, excellent color tone, and high heat resistance, the molar ratio (B1) / (B2) may be 99 / 1 to 50 / 50, preferably 98 / 2 to 60 / 40, more preferably 97 / 3 to 70 / 30, more preferably 95 / 5 to 75 / 25, and most preferably 90 / 10 to 80 / 20. When the ratio of the former (B1) to the latter (B2) is equal to or greater than the lower limit, the color tone tends to be easily improved, and when it is equal to or less than the upper limit, the heat resistance and refractive index tend to be easily improved.

[0136] The fluorenediol units (B2) may account for, for example, 1 mol % or more, preferably 3 mol % or more, of the total diol units (B), and can be selected, for example, from a range of about 3 to 70 mol %, preferably 5 to 60 mol %, further preferably 10 to 50 mol %, further preferably 15 to 40 mol %, and most preferably 20 to 35 mol %. When the proportion of the fluorenediol units (B2) is equal to or greater than the lower limit, the color tone tends to be improved.

[0137] (B3) Aromatic diol unit represented by formula (6) The aromatic diol unit represented by the formula (6) is a unit different from the fluorenediol unit represented by the formula (5).1 Examples of the linking group represented by the following formula (9) include

[0138] [ka] (In the formula, R 8a and R 8b each independently represents a hydrogen atom, an alkyl group, a fluoroalkyl group, a cycloalkyl group, or an aryl group.

[0139] Examples of the alkylene group include an optionally fluorinated hydrocarbon group represented by the following formula:

[0140] In the formula (9), R 8a and R 8b Examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. 1-10 These alkyl groups can be used alone or in combination of two or more. Among these alkyl groups, C 1-3 Alkyl groups are preferred.

[0141] R 8a and R 8b The fluoroalkyl group represented by the formula (I) is a perfluoro C group such as a trifluoromethyl group. 1-3 Examples of cycloalkyl groups include C alkyl groups such as cyclohexyl groups. 5-12 Examples of the aryl group include C aryl groups such as phenyl groups. 6-12 The aryl group is an aryl group that does not have a fluorene ring.

[0142] X 1 Examples of the alkylene group having 2 or more carbon atoms represented by the formula include an ethylene group, a trimethylene group, and a tetramethylene group. 2-6Examples of the cycloalkylidene group include C alkylene groups such as cyclohexylidene groups. 5-12 Examples thereof include a cycloalkylidene group.

[0143] Preferred Group X 1 Examples of R include a direct bond, an optionally fluorinated hydrocarbon group represented by the formula (9), and a sulfonyl group. Among these, an optionally fluorinated hydrocarbon group represented by the formula (9) is preferred, and an alkylidene group is more preferred. In the formula (9), R 8a and R 8b is a hydrogen atom or C 1-3 A hydrocarbon group (alkylidene group) that is an alkyl group is more preferred, and a C methylidene group (methylene group) or an isopropylidene group is preferred. 1-4 Alkylidene groups are more preferred.

[0144] In the formula (6), Z 4a and Z 4b The arene ring represented by the formula: 1 The arene ring can be selected from the arene rings exemplified below.

[0145] A 4a and A 4b The alkylene group (linear or branched alkylene group) represented by the formula (I), including preferred embodiments thereof, is 3a and A 3b The ranges of the repeating numbers n4a and n4b, including the preferred ranges, can be selected from the ranges described for n3a and n3b.

[0146] Ring Z 4a and ring Z 4b The group [-O-(A 4a O) n4a -] and the group [-O-(A 4b O) n4b -] is substituted at the ring Z 4a and ring Z 4b is a benzene ring, the group X 1It is preferable that the substituent is at any one of the 2-, 3- and 4-positions of the phenyl group bonded to the group, particularly the 3- or 4-position, and particularly the 4-position.

[0147] R 6a and R 6b The substituents (non-reactive or non-polymerizable substituents) represented by R, including preferred embodiments thereof, 4a and R 4b The ranges of the substitution numbers m6a and m6b, including the preferred ranges, can be selected from the ranges described for the substitution numbers m4a and m4b.

[0148] Substituent R 6a and R 6b The substitution position of is not particularly limited, and 4a and ring Z 4b is a benzene ring, the group X 1 The 2- and / or 6-positions, the 3- and / or 5-positions of each phenyl group bonded to are preferred, and the 3- and / or 5-positions are particularly preferred.

[0149] Examples of the aromatic diol component (b3) corresponding to the aromatic diol unit (B3) include bisphenols such as bisphenol F, bisphenol AD, bisphenol A, bisphenol C, bisphenol G, and bisphenol S; biphenols such as p,p'-biphenol; binaphthols such as binaphthol; and C of these diol components. 2-4 Examples include alkylene oxide (or alkylene carbonate, haloalkanol) adducts.

[0150] These aromatic diol units (B3) can be used alone or in combination. A preferred aromatic diol unit (B3) is the aromatic diol unit represented by the formula (6) above, wherein X 1 C 1-4 An alkylidene group, ring Z 4a and ring Z 4b is a benzene ring, and A 4a and A 4b C 2-3Diol units which are alkylene groups, n4a and n4b are integers of 1 or more, and m6a and m6b are 0; more preferably, diol units derived from an ethylene oxide adduct of a bisphenol, such as an ethylene oxide adduct of bisphenol A. The proportion of the aromatic diol units (B3) in the aromatic diol units (B3) can be selected, for example, from a range of about 10 to 100 mol %, and is preferably 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably 100 mol % in the following stepwise manner. When the proportion of the aromatic diol units (B3) is equal to or greater than the lower limit, the refractive index and heat resistance tend to be improved.

[0151] The molar ratio of the long-chain aliphatic diol unit (B1) to the aromatic diol unit (B3) can be selected from a range of about (B1) / (B3)=90 / 10 to 1 / 99, for example, 80 / 20 to 10 / 90, preferably 70 / 30 to 20 / 80, more preferably 60 / 40 to 30 / 70, and even more preferably 50 / 40 to 40 / 60. When the ratio of (B1) to (B3) is equal to or higher than the lower limit, the color tone tends to be improved, whereas when it is equal to or lower than the upper limit, the heat resistance and refractive index tend to be improved.

[0152] The aromatic diol unit (B3) may account for, for example, 1 mol % or more, preferably 3 mol % or more, of the total diol units (B), and can be selected, for example, from a range of about 3 to 70 mol %, preferably 5 to 50 mol %, further preferably 7 to 40 mol %, further preferably 10 to 30 mol %, and most preferably 15 to 25 mol %. When the proportion of the aromatic diol unit (B3) is equal to or greater than the lower limit, the color tone tends to be improved.

[0153] (B4) Alicyclic diol unit represented by formula (7) In the formula (7), X 2 The linking group represented by X, including preferred embodiments thereof, 1 The linking group can be selected from the linking groups exemplified above.

[0154] In the formula (7), Z 5a and Z 5bThe aliphatic hydrocarbon ring represented by the formula (I) is, including preferred embodiments thereof, Z 2 The aliphatic hydrocarbon ring can be selected from the aliphatic hydrocarbon rings exemplified below.

[0155] A 5a and A 5b The alkylene group (linear or branched alkylene group) represented by the formula (I), including preferred embodiments thereof, is 3a and A 3b The alkylene group can be selected from the alkylene groups exemplified as the alkylene group represented by the following formula:

[0156] The repeating numbers n5a and n5b are each an integer of 0 or more, and can be selected, for example, from the range of integers 0 to 15, preferably an integer of 0 to 10, an integer of 0 to 8, an integer of 0 to 6, an integer of 0 to 4, an integer of 0 to 2, or 0 or 1, with 0 being the most preferred. When n5a and n5b are below the upper limit, the heat resistance and refractive index tend to improve. Furthermore, n5a and n5b may be the same or different. When n5a and n5b are each an integer of 2 or more, two or more alkylene groups A 5a and A 5b The types may be the same or different.

[0157] Ring Z 5a and ring Z 5b The group [-O-(A 5a O) n5a -] and the group [-O-(A 5b O) n5b -] is substituted at the ring Z 5a and ring Z 5b is a cyclohexane ring, the group X 2 It is preferable that the cyclohexyl group bonded to the cyclohexyl group be 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 cyclohexyl group bonded to the cyclohexyl group.

[0158] R 7a and R 7b The substituent (non-reactive substituent or non-polymerizable substituent) represented by the formula (I) is preferably R 4a and R 4bThe ranges of the substitution numbers m7a and m7b, including the preferred ranges, can be selected from the ranges described for the substitution numbers m4a and m4b.

[0159] Substituent R 7a and R 7b The substitution position of is not particularly limited, and 5a and ring Z 5b is a cyclohexane ring, the group X 2 The 2- and / or 6-positions, the 3- and / or 5-positions of each cyclohexyl group bonded to are preferred, and the 3- and / or 5-positions are particularly preferred.

[0160] Examples of the alicyclic diol component (b4) corresponding to the alicyclic diol unit (B4) include hydrogenated bisphenols such as hydrogenated bisphenol F (hydrogenated product of bisphenol F), hydrogenated bisphenol AD, hydrogenated bisphenol A, hydrogenated bisphenol C, hydrogenated bisphenol G, and hydrogenated bisphenol S; hydrogenated biphenols such as hydrogenated p,p'-biphenol; hydrogenated binaphthols such as hydrogenated binaphthol; and C of these diol components. 2-4 Examples include alkylene oxide (or alkylene carbonate, haloalkanol) adducts.

[0161] These alicyclic diol units (B4) can be used alone or in combination of two or more. A preferred aromatic diol unit (B4) is the aromatic diol unit represented by the formula (7) above, wherein X 2 C 1-4 An alkylidene group, ring Z 5a and ring Z 5b is a cyclohexane ring, and A 5a and A 5b C 2-3Diol units which are alkylene groups, n5a and n5b are integers of 0 or greater, and m7a and m7b are 0; more preferably, diol units derived from an ethylene oxide adduct of a hydrogenated bisphenol, such as an ethylene oxide adduct of hydrogenated bisphenol A. The proportion of the alicyclic diol units (B4) in the alicyclic diol units (B4) can be selected, for example, from a range of about 10 to 100 mol%, and is preferably 50 mol% or greater, 70 mol% or greater, 90 mol% or greater, and more preferably 100 mol% in the following stepwise manner. When the proportion of the preferred alicyclic diol units (B4) is equal to or greater than the lower limit, the refractive index and heat resistance tend to be improved.

[0162] The molar ratio of the long-chain aliphatic diol unit (B1) to the alicyclic diol unit (B4) can be selected from the range of about (B1) / (B4) = 95 / 5 to 1 / 99, for example, 93 / 7 to 10 / 90, preferably 90 / 10 to 30 / 70, more preferably 80 / 20 to 50 / 50, and even more preferably 70 / 30 to 60 / 40. When the ratio of (B1) to (B4) is equal to or higher than the lower limit, the color tone tends to be improved, whereas when it is equal to or lower than the upper limit, the heat resistance and refractive index tend to be improved.

[0163] The alicyclic diol unit (B4) may be, for example, 1 mol % or more, preferably 3 mol % or more, and can be selected, for example, from a range of about 3 to 70 mol %, preferably 5 to 60 mol %, further preferably 10 to 50 mol %, further preferably 15 to 40 mol %, and most preferably 20 to 30 mol % of the total diol units (B). When the proportion of the alicyclic diol unit (B4) is equal to or higher than the lower limit, the color tone tends to be improved.

[0164] The molar ratio of the long-chain aliphatic diol unit (B1) to the total amount of the fluorenediol unit (B2), aromatic diol unit (B3), and alicyclic diol unit (B4) can be selected from the range of about 90 / 10 to 1 / 99, e.g., 70 / 30 to 5 / 95, preferably 60 / 40 to 10 / 90, more preferably 50 / 50 to 20 / 80, and even more preferably 40 / 60 to 25 / 75. When the ratio of the former (B1) to the latter [(B2) + (B3) + (B4)] is above the lower limit, color tone tends to be improved, while when it is below the upper limit, heat resistance and refractive index tend to be improved.

[0165] (B5) Short-chain aliphatic diol unit represented by formula (8) The polyester resin of the present invention may further contain a short-chain aliphatic diol unit (B5) represented by the above formula (8) in order to facilitate improvement of polymerization reactivity.

[0166] In the formula (8), A 6 The alkylene group represented by the formula (I) is not particularly limited as long as it is an alkylene group (straight-chain or branched-chain alkylene group) having 4 or less carbon atoms in the main chain. Examples of the alkylene group include C 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 2-4 An alkylene group is exemplified.

[0167] Alkylene Group A 6 The number of carbon atoms may be 4 or less, for example 2 to 4, preferably 2 to 3, and more preferably 2, in terms of excellent polymerizability and ease of improving color tone.

[0168] Alkylene Group A 6 The main chain has, for example, 2 to 4 carbon atoms, preferably 2 to 3 carbon atoms, and more preferably 2 carbon atoms.

[0169] Among such alkylene groups, C 2-4 Alkylene groups are preferred, and C groups such as ethylene and propylene groups are preferred because they have excellent polymerizability and are easy to improve color tone. 2-3An alkylene group is more preferred, and an ethylene group is most preferred.

[0170] The repeat number n6 may be an integer of 1 or more, for example, an integer of 1 to 10, and is preferably an integer of 1 to 4, an integer of 1 to 3, or 1 or 2, with 1 being particularly preferred. When n6 is an integer of 2 or more, two or more alkylene groups A 6 The types may be different, but are preferably the same.

[0171] Examples of the aliphatic diol component (b5) corresponding to the short-chain aliphatic diol unit (B5) include C olefins such as ethylene glycol, propylene glycol (or 1,2-propanediol), trimethylene glycol (or 1,3-propanediol), 1,2-butanediol, 1,3-butanediol, and tetramethylene glycol (or 1,4-butanediol). 2-4 Alkylene glycols; di- or deca-C alkylene glycols such as diethylene glycol, dipropylene glycol, and triethylene glycol 2-4 alkylene glycols and the like.

[0172] These short-chain aliphatic diol units (B5) may be contained alone or in combination of two or more. A preferred short-chain aliphatic diol unit (B5) is a diol represented by the formula (8): 6 C 2-4 a diol unit in which n6 is an alkylene group and n6 is 1; more preferably a C 2-3 It is a diol unit derived from alkylene glycol. The proportion of the preferred short-chain aliphatic diol units (B5) in the short-chain aliphatic diol units (B5) can be selected, for example, from a range of about 10 to 100 mol %, and is preferably 50 mol % or more, 70 mol % or more, 90 mol % or more, and more preferably 100 mol % in the following stepwise manner. When the proportion of the preferred short-chain aliphatic diol units (B5) is equal to or higher than the lower limit, polymerization reactivity tends to be improved.

[0173] The molar ratio of the long-chain aliphatic diol unit (B1) to the short-chain aliphatic diol unit (B5) can be selected from the range of about (B1) / (B5) = 70 / 30 to 1 / 99, for example, 50 / 50 to 3 / 97, preferably 40 / 60 to 5 / 95, more preferably 30 / 70 to 10 / 90, and more preferably 25 / 75 to 15 / 85. From the viewpoint of easily improving a high refractive index, excellent color tone, and high heat resistance, the molar ratio (B1) / (B5) is 70 / 30 to 10 / 90, preferably 60 / 40 to 15 / 85, more preferably 50 / 50 to 20 / 80, and more preferably 45 / 55 to 25 / 75. In particular, from the viewpoint of achieving an excellent balance between a high refractive index, excellent color tone, and high heat resistance, the ratio (molar ratio) is 40 / 60 to 10 / 90, preferably 30 / 70 to 20 / 80, and more preferably 35 / 65 to 25 / 75. When the ratio of the former (B1) to the latter (B5) is equal to or higher than the lower limit, color tone tends to be easily improved, and when it is equal to or lower than the upper limit, polymerization reactivity tends to be easily improved.

[0174] The short-chain aliphatic diol units (B5) may be, for example, 1 mol % or more, preferably 5 mol % or more, based on the total diol units (B). The content can be selected from a range of, for example, about 5 to 90 mol %, preferably 5 to 75 mol %, more preferably 10 to 70 mol %, more preferably 30 to 65 mol %, and most preferably 50 to 63 mol %. From the viewpoint of facilitating improvements in refractive index, color tone, and heat resistance, the short-chain aliphatic diol units (B5) may be, for example, 2 to 70 mol %, preferably 3 to 50 mol %, more preferably 5 to 40 mol %, more preferably 7 to 35 mol %, and most preferably 10 to 30 mol % based on the total diol units (B). In particular, from the viewpoint of achieving an excellent balance between a high refractive index, excellent color tone, and high heat resistance, the short-chain aliphatic diol units (B5) are, for example, 5 to 65 mol %, preferably 10 to 50 mol %, and more preferably 20 to 40 mol % based on the total diol units (B). When the proportion of the short-chain aliphatic diol unit (B5) is at least the lower limit, the polymerization reactivity tends to be improved.

[0175] The total amount of the long-chain aliphatic diol units (B1), the fluorenediol units (B2) and the short-chain aliphatic diol units (B5) in the total diol units (B) may be, for example, 50 mol% or more, for example, 80 mol% or more, preferably 90 mol% or more, further preferably 95 mol% or more, more preferably 99 mol% or more, and most preferably 100 mol%. When the total amount is equal to or more than the lower limit, the refractive index, color tone and heat resistance tend to be improved.

[0176] The total amount of the long-chain aliphatic diol units (B1), the fluorenediol units (B2), the aromatic diol units (B3), the alicyclic diol units (B4) and the short-chain aliphatic diol units (B5) in the total diol units (B) may be, for example, 50 mol% or more, for example, 80 mol% or more, preferably 90 mol% or more, further preferably 95 mol% or more, more preferably 99 mol% or more, and most preferably 100 mol%. When the total amount is equal to or more than the lower limit, the refractive index, color tone and heat resistance tend to be improved.

[0177] (B6) Other diol units The diol unit (B) may further contain other diol units (B6) as necessary. Examples of the other diol units (B6) include alicyclic diol units (excluding the alicyclic diol units (B4)) and aromatic diol units (excluding the fluorenediol units (B2) and the aromatic diol units (B3)).

[0178] Examples of the alicyclic diol component corresponding to the alicyclic diol unit (alicyclic diol unit different from the alicyclic diol unit (B4)) include cyclohexanediols such as 1,4-cyclohexanediol (or 1,4-dihydroxycyclohexane); bis(hydroxy C) such as cyclohexane-1,3-dimethanol [or 1,3-bis(hydroxymethyl)cyclohexane] and cyclohexane-1,4-dimethanol; 1-3 alkyl)cyclohexane; bis(hydroxy C such as decalin-2,6-dimethanol 1-3alkyl)decalin; bis(hydroxy C such as adamantane dimethanol 1-3 alkyl)adamantanes; bis(hydroxy C) such as tricyclodecane dimethanol 1-3 alkyl)tricyclodecane, etc.

[0179] Examples of the aromatic diol component corresponding to the aromatic diol unit (aromatic diol unit different from the fluorenediol unit (B2) and the aromatic diol unit (B3)) include dihydroxyarenes such as hydroquinone and resorcinol; aromatic aliphatic diols such as benzenedimethanol; and C of these diol components. 2-4 Examples include alkylene oxide (or alkylene carbonate, haloalkanol) adducts.

[0180] These other diol units may be contained alone or in combination of two or more kinds. Among these, cyclohexanediol is preferred.

[0181] The proportion of the other diol units (B6) in the total diol units (B) may be, for example, 50 mol% or less, preferably 30 mol% or less, 10 mol% or less, and 5 mol% or less in the following stepwise manner. The diol units (B) preferably do not substantially contain other diol units (B6), and particularly preferably do not contain any other diol units (B6).

[0182] (C) Other structural units The polyester resin of the present disclosure may contain other structural units (C) different from the dicarboxylic acid units (A) and the diol units (B), as needed.

[0183] Examples of other structural units (C) include structural units derived from hydroxyalkanoic acids and corresponding lactones, polyfunctional polymerization components having three or more carboxyl groups and / or hydroxyl groups, and carbonate bond-forming components.

[0184] Examples of the hydroxyalkanoic acids and corresponding lactones include hydroxyalkanoic acids such as lactic acid, 3-hydroxybutyric acid, and 6-hydroxyhexanoic acid; and lactones corresponding to hydroxyalkanoic acids such as ε-caprolactone.

[0185] Examples of the polyfunctional polymerization component include polyfunctional polymerization components having a total of three or more carboxyl groups and / or hydroxyl groups, such as trivalent or higher polycarboxylic acids such as trimellitic acid and pyromellitic acid, and trivalent or higher polyhydric alcohols such as glycerin and pentaerythritol.

[0186] The carbonate bond-forming component may be any compound capable of forming a carbonate bond by reaction with two diol components. That is, the "structural unit derived from the carbonate bond-forming component" refers to a carbonyl group, which forms a carbonate bond together with the terminal oxygen atoms of the two diol units bonded adjacent to this carbonyl group. That is, the polyester resin may be a polyester carbonate resin. Typical carbonate bond-forming components include, for example, phosgenes such as phosgene and triphosgene, and carbonate diesters such as diphenyl carbonate.

[0187] The proportion of such other structural units (C) may be 50 mol% or less relative to the total structural units [total amount of dicarboxylic acid units (A), diol units (B), and other structural units (C)], and is preferably 40 mol% or less, 30 mol% or less, 20 mol% or less, 10 mol% or less, and 5 mol% or less in the following stepwise manner, and usually, other structural units (C) are often substantially absent. The proportion may be about 0 to 10 mol%, for example, about 0.01 to 1 mol%.

[0188] The polyester resin of the present disclosure preferably contains substantially no titanium, and particularly preferably does not contain titanium, in order to facilitate improvement in color tone.

[0189] The polyester-based resin of the present disclosure may or may not contain a colorant such as a dye or pigment. The polyester-based resin of the present disclosure can reduce color such as yellowness without adding a colorant such as a dye or pigment.

[0190] [Method of manufacturing polyester resin] The method for producing the polyester resin of the present disclosure is not particularly limited except for using, as polymerization components, a dicarboxylic acid component (a) [i.e., a dicarboxylic acid component (a) containing a dicarboxylic acid component (a1) corresponding to the aromatic dicarboxylic acid unit (A1) and / or a dicarboxylic acid component (a2) corresponding to the fluorenedicarboxylic acid unit (A2)] and a diol component (b) [i.e., a diol component (b) containing a diol component (b1) corresponding to the long-chain aliphatic diol unit (B1) and a diol component (b2) corresponding to the fluorenediol unit (B2), and, if necessary, a diol component (b3) corresponding to the short-chain aliphatic diol unit (B3)], and a conventional method can be used.

[0191] The polyester resin of the present disclosure can be produced by reacting (polymerizing) the dicarboxylic acid component (a) with the diol component (b), and can be prepared by a conventional method such as melt polymerization, solution polymerization, or interfacial polymerization, with melt polymerization being preferred. The reaction may be carried out in the presence or absence of a solvent depending on the polymerization method.

[0192] The method for producing the polyester resin of the present disclosure may be either a transesterification method (transesterification reaction) or a direct esterification method. In the transesterification method, an alkyl ester, which is an ester-forming derivative, may be used as the dicarboxylic acid component (b), and then the resulting product may be subjected to a polycondensation reaction.

[0193] The ratio (or charge ratio) of the dicarboxylic acid component (a) to the diol component (b) is, for example, the former / latter (molar ratio) = 1 / 1.2 to 1 / 0.8, preferably 1 / 1.1 to 1 / 0.9, but it is not necessarily within this range, and at least one component contained in the polymerization components may be used in excess of the intended introduction ratio. For example, a diol component such as ethylene glycol that can be distilled from the reaction system may be used in excess of the ratio (or introduction ratio) introduced into the polyester-based resin.

[0194] The reaction is usually carried out in an atmosphere of an inert gas, such as nitrogen gas, or a rare gas such as helium or argon. Alternatively, the reaction may be carried out under reduced pressure, for example, at a pressure of 1×10 2 ~1×10 4 The reaction temperature can be selected depending on the polymerization method. For example, the reaction temperature in the melt polymerization method is 150 to 320°C, preferably 180 to 310°C, and more preferably 200 to 300°C. In particular, in the transesterification method, the reaction temperature of the transesterification reaction may be 200 to 260°C, preferably 220 to 250°C, and the reaction temperature of the polycondensation reaction may be 220 to 300°C, preferably 240 to 280°C.

[0195] (catalyst) The reaction may be carried out in the presence of a catalyst. Conventional esterification catalysts, such as metal catalysts, can be used as the catalyst. Examples of metal catalysts include metal compounds containing alkali metals such as sodium; alkaline earth metals such as magnesium, calcium, and barium; transition metals such as titanium, manganese, and cobalt; metals in Group 12 of the periodic table such as zinc and cadmium; metals in Group 13 of the periodic table such as aluminum; metals in Group 14 of the periodic table such as germanium and lead; and metals in Group 15 of the periodic table such as antimony. Examples of metal compounds include alkoxides; organic acid salts such as acetates and propionates; inorganic acid salts such as borates and carbonates; oxides, and hydrates thereof.

[0196] Representative metal compounds include germanium compounds such as germanium dioxide, germanium hydroxide, germanium oxalate, germanium tetraethoxide, and germanium-n-butoxide; antimony compounds such as antimony trioxide, antimony acetate, and antimony ethylene glycolate; titanium compounds such as tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate (titanium(IV) tetrabutoxide), titanium oxalate, and potassium titanium oxalate; manganese compounds such as manganese acetate tetrahydrate; and calcium compounds such as calcium acetate monohydrate.

[0197] These catalysts can be used alone or in combination of two or more. When using a plurality of catalysts, each catalyst can be added according to the progress of the reaction.

[0198] Among these catalysts, manganese compounds such as manganese acetate tetrahydrate, calcium compounds such as calcium acetate monohydrate, germanium compounds such as germanium dioxide, and titanium compounds such as titanium(IV) tetrabutoxide are preferred. In particular, germanium compounds such as germanium dioxide are preferred as catalysts because they can improve color tone. In the transesterification method, a germanium compound is preferably used as a polycondensation catalyst. It is particularly preferred to use manganese compounds such as manganese acetate tetrahydrate and / or calcium compounds such as calcium acetate monohydrate as organic acid metal salts as transesterification reaction catalysts, and a germanium compound as a polycondensation catalyst. Furthermore, it is preferred not to use titanium compounds as catalysts because it is easier to improve color tone.

[0199] The amount of the catalyst used is, for example, 0.0001 to 1 mol, preferably 0.001 to 0.7 mol, and more preferably 0.01 to 0.4 mol, relative to 100 mol of the dicarboxylic acid component (a).

[0200] In the transesterification reaction, when a manganese compound and / or a calcium compound as a transesterification catalyst is combined with a germanium compound as a polycondensation catalyst, the amount of the transesterification catalyst used is, for example, 0.01 to 0.5 mol, preferably 0.05 to 0.3 mol, per 100 mol of the dicarboxylic acid component (a), and the amount of the polycondensation catalyst used is, for example, 0.01 to 1 mol, preferably 0.1 to 0.5 mol, per 100 mol of the dicarboxylic acid component (b).

[0201] (stabilizer) The reaction may be carried out in the presence of a stabilizer such as a heat stabilizer or an antioxidant, if necessary. Usually, a heat stabilizer is often used.

[0202] Commonly used heat stabilizers include phosphorus compounds and / or phenol compounds, such as phosphates, phosphites, phosphines, and phosphorus compounds having a t-butylphenyl group.

[0203] Examples of the phosphates include alkyl phosphates such as dibutyl phosphate (dibutyl phosphate or dibutyl phosphoric acid), trimethyl phosphate, and triethyl phosphate; and aryl phosphates such as triphenyl phosphate.

[0204] Examples of phosphites include phosphorous acid; trimethyl phosphite, triethyl phosphite, alkyl phosphites; aryl alkyl phosphites such as diphenyl isodecyl phosphite and phenyl diisodecyl phosphite; and aryl phosphites such as triphenyl phosphite and tris(nonylphenyl) phosphite.

[0205] Examples of phosphines include hypophosphorous acid; alkyl phosphines such as trimethylphosphine; and aryl phosphines such as triphenylphosphine, tri-2,4-dimethylphenylphosphine, tri-2,4,6-trimethylphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tri-o-anisylphosphine, and tri-p-anisylphosphine.

[0206] Examples of phosphorus compounds having a t-butylphenyl group include tris(2,4-di-t-butylphenyl)phosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene phosphite, 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, and 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane ("ADK STAB"). PEP-36"), phosphorus-based compounds such as 2,2-methylenebis(4,6-di-t-butylphenyl) 2-ethylhexyl phosphite; and hindered phenol-based compounds such as diethyl (3,5-di-t-butyl-4-hydroxybenzyl) phosphonate, ethyl di(3,5-di-t-butyl-4-hydroxybenzyl) phosphonate, and 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphine.

[0207] Examples of the phenolic compound include a hindered phenolic compound having a t-butyl group and a phenolic hydroxyl group, and a hindered phenolic compound having a (meth)acryloyl group.

[0208] Examples of hindered phenol compounds having a t-butyl group and a phenolic hydroxyl group include octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (ADEKA CORPORATION's "ADEKA STAB AO-50"), 1,6-hexanediol bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene glycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], tetrakis[methylene-3-(3,5-di-t-butyl Mono- or tetra(t-butylphenyl)propionate]methane, 3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, etc. alkane bis- or tris(t-butylphenol)s such as 2,2'-methylenebis(6-t-butyl-4-methyl)phenol and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane; tris(t-butylphenol)benzenes such as 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxy)benzene and 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene; and tris(t-butylphenol) isocyanurates such as tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate and tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione.

[0209] Examples of hindered phenol compounds having a (meth)acryloyl group include 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate and 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate.

[0210] These phenolic compounds can be used alone or in combination of two or more. Among these, hindered phenolic compounds having a t-butyl group and a phenolic hydroxyl group are preferred, and mono- or tetra(t-butylphenol) propionate esters such as octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate are particularly preferred.

[0211] These heat stabilizers (phosphorus compounds and / or phenol compounds) can be used alone or in combination of two or more. Among these, phosphates are widely used.

[0212] The amount of the heat stabilizer used is, for example, 0.0001 to 1 mol, preferably 0.001 to 0.7 mol, and more preferably 0.01 to 0.4 mol, relative to 100 mol of the dicarboxylic acid component (a).

[0213] [Characteristics of polyester resin] The weight-average molecular weight Mw of the polyester resin of the present disclosure can be measured by gel permeation chromatography (GPC) or the like, and can be selected in polystyrene equivalent from a range of, for example, 10,000 to 100,000, preferably in the following stepwise manner: 15,000 to 100,000, 20,000 to 80,000, 25,000 to 50,000, and most preferably 28,000 to 40,000. If the molecular weight is equal to or higher than the lower limit, heat resistance and moldability (or mechanical properties) tend to be improved, and if it is equal to or lower than the upper limit, moldability tends to be improved.

[0214] The polyester resin of the present disclosure has a high refractive index. Specifically, the refractive index nD of the polyester resin of the present disclosure is, at a temperature of 20°C and a wavelength of 589 nm, for example, 1.6 or more, preferably 1.63 or more, and can be selected, for example, from a range of about 1.6 to 1.7, preferably 1.61 to 1.68, 1.62 to 1.67, 1.63 to 1.665, 1.64 to 1.66, and most preferably 1.65 to 1.655.

[0215] The Abbe number of the polyester resin of the present disclosure at a temperature of 20°C is, for example, 10 to 50, preferably 13 to 30, 14 to 25, 15 to 23, 16 to 21, and more preferably 18 to 20 in the following stepwise order.

[0216] The glass transition temperature Tg of the polyester resin of the present disclosure may be 90° C. or higher, for example, 90 to 160° C., preferably 100 to 155° C., further preferably 110 to 150° C., even more preferably 120 to 145° C., and most preferably 130 to 140° C. If the glass transition temperature Tg is equal to or higher than the lower limit, heat resistance tends to be improved, and if it is equal to or lower than the upper limit, moldability tends to be improved.

[0217] The polyester resin of the present disclosure also has excellent color tone. In particular, the polyester resin of the present disclosure has excellent color (L * a * b * In the color space, chromaticity b * The absolute value of chromaticity b may be 10 or less, and yellow and blue tinges are reduced, resulting in excellent color tone. * The absolute value of chromaticity b is preferably 5 or less, 3.5 or less, 3 or less, 2.4 or less, 2 or less, 1.5 or less, 1 or less, and 0.5 or less in the following stepwise manner, and may be, for example, about 0.05 to 2. * When it is equal to or less than the upper limit, yellowish or bluish tinge can be reduced, and color tone tends to be improved.

[0218] The polyester resin of the present disclosure has a color with a brightness of L *The lightness L may be 50 or more, preferably 60 or more, further preferably 70 or more, even more preferably 75 or more, and most preferably 80 or more, and may be, for example, about 80 to 90. * When the value is equal to or greater than the lower limit, the lightness tends to be high and the color tone tends to be improved.

[0219] The polyester resin of the present disclosure has a chromaticity of a * The absolute value of chromaticity a may be 10 or less, and preferably is 8 or less, 5 or less, 3 or less, 1 or less, 0.5 or less, and 0.1 or less in the following stepwise manner. * When it is equal to or less than the upper limit, reddish and greenish hues can be reduced, and the color tone tends to be improved.

[0220] In this specification and claims, the weight average molecular weight Mw, refractive index nD, Abbe number, glass transition temperature Tg, and color can be measured by the methods described in the examples below.

[0221] [Molded body] The molded article of the present disclosure contains at least the polyester resin and exhibits excellent optical properties, and therefore can be used as optical components such as light guide plates, optical fibers, and optical lenses.

[0222] The molded article of the present disclosure may contain conventional additives. Examples of additives include fillers or reinforcing agents such as carbon materials, colorants such as dyes and pigments, conductive agents, flame retardants, plasticizers, lubricants, release agents, antistatic agents, dispersants, flow control agents, leveling agents, antifoaming agents, surface modifiers, hydrolysis inhibitors, stabilizers, and stress-reducing agents. Examples of stabilizers include antioxidants, UV absorbers, and heat stabilizers. Examples of stress-reducing agents include silicone oil, silicone rubber, various plastic powders, and various engineering plastic powders. These additives can be used alone or in combination of two or more. The total amount of these additives may be, for example, 50 parts by mass or less, preferably 30 parts by mass or less, 0 to 10 parts by mass, or approximately 0.1 to 5 parts by mass, per 100 parts by mass of the polyester resin.

[0223] The molded article of the present disclosure can be produced using, for example, injection molding, injection compression molding, extrusion molding, transfer molding, blow molding, pressure molding, casting molding, etc. Of these, injection molding is preferred.

[0224] The shape of the molded body is not particularly limited, and examples thereof include one-dimensional structures such as linear, fibrous (or fiber-like) and thread-like structures, two-dimensional structures such as film-like, sheet-like and plate-like structures, and three-dimensional structures such as lens-like structures such as concave or convex lenses, rod-like structures and hollow (tubular) structures. [Example]

[0225] 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 evaluation items and raw materials are shown below.

[0226] [Evaluation items] (Polyester Resin Composition) The sample was dissolved in deuterated chloroform (CDCl3) containing tetramethylsilane as an internal standard, and the NMR spectrum was measured using a nuclear magnetic resonance spectrometer (BRUKER "AVANCE III HD"). 1 The H-NMR spectrum was measured. The integral values ​​of the peaks derived from each reaction component were determined for the obtained spectrum, and the proportion of each reaction component (structural unit) introduced into the polyester resin was calculated.

[0227] (molecular weight) The sample was dissolved in chloroform, and the weight average molecular weight Mw in terms of polystyrene was determined using gel permeation chromatography ("HLC-8320GPC" manufactured by Tosoh Corporation).

[0228] (Refractive index nD) The refractive index was measured as follows. The sample was heat-pressed at 180 to 220°C to form a film with a thickness of 200 to 300 μm. This film was cut into strips measuring 20 to 30 mm in length and 10 mm in width to obtain test pieces. The refractive index nD of the obtained test pieces at 589 nm (D line) was measured using a multi-wavelength Abbe refractometer ("DR-M4 (circulating constant temperature water bath 60-C3)" manufactured by Atago Co., Ltd.) at a measurement temperature of 20°C and diiodomethane as a contact liquid.

[0229] (Abbe number) Using the test piece for measuring the refractive index (the test piece for measuring the refractive index nD at 589 nm (D line)), the refractive indices nF and nC were measured in the same manner as for the refractive index nD, except that the measurement wavelengths were changed to 486 nm (F line) and 656 nm (C line). From the obtained refractive indices nF, nD, and nC at each wavelength, the Abbe number was calculated using the following formula.

[0230] (Abbe number) = (nD-1) / (nF-nC)

[0231] (glass transition temperature Tg) Measurement was carried out using a differential scanning calorimeter ("EXSTAR6000 DSC6220 ASD-2" manufactured by SII NanoTechnology Inc.) in a nitrogen gas atmosphere at a temperature increase rate of 10°C / min.

[0232] (color) Using a spectrophotometer (Konica Minolta, Inc. "CM-5"), in accordance with JIS Z 8722 condition c, pellet-shaped samples were packed into a petri dish with a measurement diameter of 30 mm, and L was measured under the conditions of reflection measurement, specular reflection light processing SCI, and observation illuminant D65. * , a * , b * Measurements were carried out.

[0233] [Resin raw materials (polymerization reaction components)] (Dicarboxylic acid component) 2,6-DMN: Dimethyl naphthalene-2,6-dicarboxylate represented by the following formula

[0234] [ka]

[0235] DMT: Dimethyl terephthalate represented by the following formula:

[0236] [ka]

[0237] FDP-m: 9,9-bis(2-methoxycarbonylethyl)fluorene represented by the following formula:

[0238] [ka]

[0239] DPFDP-m: 9,9-bis(2-methoxycarbonylethyl)-2,7-diphenylfluorene represented by the following formula:

[0240] [ka]

[0241] DMCD: Dimethyl cyclohexane-1,4-dicarboxylate represented by the following formula

[0242] [ka]

[0243] (Diol component) NPG: Neopentyl glycol (main chain carbon number: 3) represented by the following formula

[0244] [ka]

[0245] 3-Me-1,5-PDO: 3-methyl-1,5-pentanediol (main chain carbon number: 5) represented by the following formula

[0246] [ka]

[0247] 1,5-PDO: 1,5-pentanediol (main chain carbon number: 5) represented by the following formula

[0248] [ka]

[0249] 1,9-NDO: 1,9-nonanediol (main chain carbon number: 9) represented by the following formula

[0250] [ka]

[0251] BPEF: 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene represented by the following formula

[0252] [ka]

[0253] BOPPEF: 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]fluorene represented by the following formula

[0254] [ka]

[0255] BisA-EO: Ethylene oxide adduct of bisphenol A represented by the following formula

[0256] [ka]

[0257] Hydrogenated BisA: Hydrogenated bisphenol A represented by the following formula

[0258] [ka]

[0259] EG: Ethylene glycol (main chain carbon number: 2) represented by the following formula

[0260] [ka]

[0261] 1,2-PG: Propylene glycol (main chain carbon number: 2) represented by the following formula

[0262] [ka]

[0263] 1,3-PDO: Trimethylene glycol (main chain carbon number: 3) represented by the following formula

[0264] [ka]

[0265] [Examples and Comparative Examples] Comparative Example 1 A reactor was charged with 2,6-DMN (48.9 g (200 mmol)) as the dicarboxylic acid component (a), BPEF (17.5 g (40 mmol)) as the diol component (b), EG (34.8 g (560 mmol)), and manganese acetate tetrahydrate (29.4 mg (120 μmol)) as a transesterification catalyst. The mixture was gradually heated to 240°C under a nitrogen atmosphere and stirred to carry out the transesterification reaction. After removing the alcohol produced by the transesterification reaction, trimethyl phosphate (21.0 mg (150 μmol)) as a thermal stabilizer and germanium dioxide (52.3 mg (500 μmol)) as a polycondensation catalyst were added. The temperature was gradually raised to 260°C and the pressure was reduced to 130 Pa. The polycondensation reaction was carried out while removing the EG. After the reaction was completed, the contents were removed from the reactor, and a polyester resin was obtained.

[0266] Example 1 A reactor was charged with 2,6-DMN (48.9 g, 200 mmol) as the dicarboxylic acid component (a), BPEF (17.5 g, 40 mmol), NPG (12.5 g, 120 mmol), and EG (21.1 g, 340 mmol) as the diol component (b), and manganese acetate tetrahydrate (29.4 mg, 120 μmol) as a transesterification catalyst. The mixture was gradually heated to 240 °C under a nitrogen atmosphere and stirred to carry out the transesterification reaction. After removing the alcohol produced by the transesterification reaction, trimethyl phosphate (21.0 mg, 150 μmol) as a thermal stabilizer and germanium dioxide (31.4 mg, 300 μmol) as a polycondensation catalyst were added. The temperature was gradually raised to 260 °C and the pressure was reduced to 130 Pa. The polycondensation reaction was carried out while removing the EG. After the reaction was completed, the contents were removed from the reactor to obtain a polyester resin.

[0267] Examples 2 to 13, 15 to 22 Polyester resins were obtained in the same manner as in Example 1, except that the dicarboxylic acid component (a) and the diol component (b) were used in the amounts shown in Tables 1, 3, 5, 7, 9 and 11.

[0268] Example 14 A reactor was charged with 29.1 g (150 mmol) of DMT as the dicarboxylic acid component (a), 46.0 g (105 mmol) of BPEF, 1.8 g (15 mmol) of 3-Me-1,5-PDO, and 25.1 g (330 mmol) of 1,3-PDO as the diol components (b), 21.1 mg (120 μmol) of calcium acetate monohydrate and 6.1 mg (18 μmol) of titanium(IV) tetrabutoxide as catalysts for the transesterification and polycondensation reactions, and 15.9 mg (30 μmol) of octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate as a thermal stabilizer. The mixture was gradually heated to 240°C under a nitrogen atmosphere with stirring to carry out the transesterification reaction. After removing the alcohol component produced by the transesterification reaction, trimethyl phosphate (5.0 mg (36 μmol)) was added as a heat stabilizer, and the temperature was gradually increased to 260°C and 130 Pa, the pressure was reduced, and a polycondensation reaction was carried out while removing EG. After the reaction was completed, the contents were removed from the reactor to obtain a polyester resin.

[0269] The charging ratios of Examples 1 to 5 and Comparative Example 1 are shown in Table 1, and the composition ratios and physical properties of the obtained polyester resins are shown in Table 2.

[0270] The charging ratios of Examples 4, 6 to 10 and Comparative Example 1 are shown in Table 3, and the composition ratios and physical properties of the obtained polyester resins are shown in Table 4.

[0271] The charging ratios of Examples 11 to 15 and Comparative Example 1 are shown in Table 5, and the composition ratios and physical properties of the obtained polyester resins are shown in Table 6.

[0272] The charging ratios of Examples 16 to 18 and Comparative Example 1 are shown in Table 7, and the composition ratios and physical properties of the obtained polyester resins are shown in Table 8.

[0273] The charging ratios of Examples 19 to 20 and Comparative Example 1 are shown in Table 9, and the composition ratios and physical properties of the obtained polyester resins are shown in Table 10.

[0274] The charging ratios of Examples 4, 21 and 22 and Comparative Example 1 are shown in Table 11, and the composition ratios and physical properties of the obtained polyester resins are shown in Table 12.

[0275] [Table 1]

[0276] [Table 2]

[0277] [Table 3]

[0278] [Table 4]

[0279] [Table 5]

[0280] [Table 6]

[0281] [Table 7]

[0282] [Table 8]

[0283] [Table 9]

[0284] [Table 10]

[0285] [Table 11]

[0286] [Table 12]

[0287] As is clear from the results in Tables 2, 4, 6, 8, 10 and 12, the chromaticity b * In particular, Examples 4 and 5 were highly effective in reducing yellowness.

[0288] As is clear from the results in Tables 2, 4, and 6, the yellowness could be reduced in Examples 11 to 15, but the yellowness was reduced more and the refractive index was higher in Examples 1 to 10. This indicates that the dicarboxylic acid unit derived from 2,6-DMN has a greater effect of reducing color than the unit derived from DMT.

[0289] In Tables 8, 10, and 12, Examples 17 and 18 contain units derived from 2,6-DMN, units derived from BPEF, and units derived from 3-Me-1,5-PDO, and although the proportion of units derived from 3-Me-1,5-PDO is lower than in Examples 1 to 10, the yellowness was reduced and the refractive index was high. 3-Me-1,5-PDO, a long-chain diol component, is less reactive than other glycol components and therefore tends to remain at the ends of the molecule, and it can be assumed that even when used in small amounts, this suppresses side reactions that cause coloration.

[0290] Furthermore, for Comparative Example 1 and Examples 4, 6 to 9, the 3-Me-1,5-PDO composition ratio (ratio in diol units) and chromaticity b *The relationship between chromaticity and chromaticity is shown in Figure 1. As is clear from Figure 1, the chromaticity b * It can be seen that the yellowness can be effectively reduced by increasing the 3-Me-1,5-PDO unit. [Industrial Applicability]

[0291] The polyester-based resin of the present disclosure exhibits excellent optical properties and can therefore be used in a variety of applications, such as coating agents or coating films, specifically, protective films for paints, inks, electronic devices, liquid crystal components, 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; and mechanical materials or mechanical components (equipment), specifically, automotive materials or components, aerospace-related materials or components, sliding members, and the like.

[0292] In particular, the polyester-based resin of the present disclosure can be effectively used as an optical component, and typical examples include optical films (optical sheets) such as films for liquid crystal displays and organic electroluminescence displays; optical lenses such as lenses for glasses and cameras; prisms, holograms, and optical fibers. However, because of its excellent color tone, it is particularly suitable for light guides such as light guide plates and cores and clads (particularly cores) of optical fibers.

Claims

1. A polyester resin containing dicarboxylic acid units (A) and diol units (B), The dicarboxylic acid unit (A) is represented by the following formula (1): 【Chemical 1】 (In the formula, Z １ indicates an arene ring, R １ represents a substituent, and m1 represents an integer of 0 or more. an aromatic dicarboxylic acid unit (A1) represented by the following formula (2): 【Chemistry 2】 (In the formula, A １ａ and A １ｂ each independently represents an alkylene group, R ２ represents a substituent, and m2 represents an integer of 0 to 8. and a fluorenedicarboxylic acid unit (A2) represented by the following formula (3): 【Chemistry 3】 (In the formula, Z ２ represents an aliphatic hydrocarbon ring, R ３ represents a substituent, and m3 represents an integer of 0 or more. and (A3) contains at least one dicarboxylic acid unit selected from the group consisting of alicyclic dicarboxylic acid units represented by the formula: The diol unit (B) is represented by the following formula (4): 【Chemistry 4】 (In the formula, A ２ represents an alkylene group having 5 or more carbon atoms, and n2 represents an integer of 1 or more. and a long-chain aliphatic diol unit (B1) represented by the formula: The following formula (5) 【Chemistry 5】 (In the formula, Z ３ａ and Z ３ｂ each independently represents an arene ring, A ３ａ and A ３ｂ each independently represents an alkylene group; n3a and n3b ​​each independently represent an integer of 0 or more; R ４ａ and R ４ｂ each independently represents a substituent; m4a and m4b each independently represents an integer of 0 or more; R ５ represents a substituent, and m5 represents an integer of 0 to 8. a fluorenediol unit (B2) represented by the following formula (6): 【Chemistry 6】 (In the formula, X １ represents a direct bond or a linking group, Z ４ａ and Z ４ｂ each independently represents an arene ring, A ４ａ and A ４ｂ each independently represents an alkylene group; n4a and n4b each independently represent an integer of 0 or more; R ６ａ and R ６ｂ each independently represents a substituent, and m6a and m6b each independently represent an integer of 0 or more. and an aromatic diol unit (B3) represented by the following formula (7): 【Chemistry 7】 (In the formula, X ２ represents a direct bond or a linking group, Z ５ａ and Z ５ｂ each independently represents an aliphatic hydrocarbon ring, A ５ａ and A ５ｂ each independently represents an alkylene group; n5a and n5b each independently represent an integer of 0 or more; R ７ａ and R ７ｂ each independently represents a substituent, and m7a and m7b each independently represent an integer of 0 or more. and (B4) at least one diol unit selected from the group consisting of alicyclic diol units represented by the following formula:

2. The diol unit (B) is represented by the following formula (8): 【Chemistry 8】 (In the formula, A ６ represents an alkylene group having 4 or less carbon atoms, and n6 represents an integer of 1 or more. The polyester resin according to claim 1, further comprising a short-chain aliphatic diol unit (B5) represented by the following formula:

3. In the formula (4), A ２ 3. The polyester resin according to claim 1, wherein n is an alkylene group having 5 or more carbon atoms in the main chain, and n2 is 1.

4. The dicarboxylic acid unit (A) contains the aromatic dicarboxylic acid unit (A1), and Z １ 3. The polyester resin according to claim 1, wherein R represents a condensed polycyclic arene ring.

5. the diol unit (B) contains the short-chain aliphatic diol unit (B5), the molar ratio of the long-chain aliphatic diol units (B1) to the total amount of the fluorenediol units (B2), the aromatic diol units (B3) and the alicyclic diol units (B4) is (B1) / (B2) [(B3)+(B4)]=70 / 30 to 5 / 95; 3. The polyester resin according to claim 2, wherein the molar ratio of the long-chain aliphatic diol unit (B1) to the short-chain aliphatic diol unit (B5) is (B1) / (B5)=50 / 50 to 3 / 97.

6. chromaticity b ＊ 6. The polyester resin according to claim 1, 2 or 5, wherein the absolute value of

7. A method for producing the polyester resin according to claim 1, 2 or 5, comprising polymerizing a dicarboxylic acid component (a) corresponding to the dicarboxylic acid unit (A) and a diol component (b) corresponding to the diol unit (B).

8. A molded article comprising the polyester resin according to claim 1, 2 or 5.

9. The molded article according to claim 8, which is an optical element.

10. The molded article according to claim 8, which is a light guide.

11. In the polyester resin containing a dicarboxylic acid unit (A) and a diol unit (B), The diol unit (B) may be a diol unit represented by the following formula (4): 【Chemistry 9】 (In the formula, A ２ represents an alkylene group having 5 or more carbon atoms, and n2 represents an integer of 1 or more. A long-chain aliphatic diol unit (B1) represented by the following formula is introduced: The chromaticity b of the polyester resin ＊ A method for reducing the absolute value of

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