CN117980375A

CN117980375A - Polycarbonate resin

Info

Publication number: CN117980375A
Application number: CN202280063102.0A
Authority: CN
Inventors: 中村昂志; 中村佳史; 林宽幸
Original assignee: Mitsubishi Chemical Corp
Current assignee: Mitsubishi Chemical Corp
Priority date: 2021-10-25
Filing date: 2022-10-21
Publication date: 2024-05-03
Also published as: WO2023074576A1; TW202334276A

Abstract

A polycarbonate resin comprising a structural unit (A), a structural unit (B) and a structural unit (C), a molded article obtained using the polycarbonate resin, a film, a retardation film and a method for producing a transparent film. The structural unit (A) is represented by formula (1) and/or formula (2). The structural unit (B) is represented by formula (3). The structural unit (C) is derived from a dihydroxy compound having an acetal ring structure. [ chemical 1][ Chemical 2][ Chemical 3]

Description

Polycarbonate resin

Technical Field

The present disclosure relates to a polycarbonate resin, a polycarbonate resin molded article, a film, a method for producing a transparent film, and a retardation film.

Background

There is an increasing need for transparent resins used in optical applications such as molded articles, optical lenses, optical films, and optical recording media, as represented by front panels of televisions and smart phones. Among them, the organic EL display has been remarkably spread, and various optical films have been developed for the purpose of improving display quality, such as improving contrast and coloring, enlarging viewing angle, preventing reflection of external light, and the like.

In the organic EL display, a 1/4 wave plate for preventing reflection of external light has been used. In order to achieve pure black display by suppressing coloring of the retardation film used in the 1/4 wave plate, it is required to have wavelength dispersibility in a wide band capable of obtaining desired retardation characteristics at each wavelength in the visible light range. As a comparable thereto, for example, patent document 1 discloses a polycarbonate copolymer having an oligofluorene structural unit and a retardation film using the polycarbonate copolymer, and discloses a retardation film exhibiting reverse wavelength dispersion in which the shorter the wavelength is, the smaller the phase difference is. Patent document 2 discloses a polycarbonate copolymer containing a structural unit derived from 6,6' -dihydroxy-3, 3' -tetramethyl-1, 1' -spiroindane (hereinafter also abbreviated as SBI) and a retardation film using the polycarbonate copolymer, which is excellent in heat resistance and optical properties.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2015-212368

Patent document 2: japanese patent laid-open publication No. 2019-178340

Disclosure of Invention

Problems to be solved by the invention

In recent years, organic EL displays have been used as displays for vehicles, and as characteristics required for retardation films used for organic EL displays, it has been demanded that the organic EL displays function without problems even in a more severe use environment than ever before. Specifically, for example, in-vehicle organic EL displays, the retardation film needs to have higher wet heat resistance than before because the retardation film is used at high temperature and high humidity.

Although the polycarbonate copolymers described in patent document 1 and patent document 2 may satisfy the required optical characteristics, the wet heat resistance is insufficient, and the optical characteristics are insufficient under a higher temperature condition and a higher humidity atmosphere than before. In addition, there is room for improvement in mechanical properties such as toughness and in melt processability.

The present disclosure has been made in view of the above-described background, and an object thereof is to provide a polycarbonate resin excellent in optical characteristics and having high wet heat resistance, mechanical properties, and melt processability, a molded article, a film, a retardation film, and a method for producing a transparent film, each obtained by using the polycarbonate resin.

Technical proposal for solving the problems

A first aspect of the present disclosure is a polycarbonate resin comprising:

A structural unit (A) represented by the following formula (1) and/or (2),

A structural unit (B) represented by the following formula (3), and

Structural unit (C) derived from a dihydroxy compound having an acetal ring structure.

[ Chemical 1]

Wherein in formula (1), R ¹～R³ each independently represents a direct bond or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms. In the formula (1), R ⁴～R⁹ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted acyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 2 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 2 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group or a cyano group. In formula (1), R ⁴～R⁹ may be the same as or different from each other, and at least two adjacent groups in R ⁴～R⁹ may be bonded to each other to form a ring.

[ Chemical 2]

Wherein in formula (2), R ¹～R³ each independently represents a direct bond or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms. In the formula (2), R ⁴～R⁹ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted acyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 2 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 2 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group or a cyano group. In formula (2), R ⁴～R⁹ may be the same as or different from each other, and at least two adjacent groups in R ⁴～R⁹ may be bonded to each other to form a ring.

[ Chemical 3]

Wherein in formula (3), R ¹⁰～R¹⁷ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. In the formula (3), X ¹ represents a direct bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.

A second aspect of the present disclosure is directed to a polycarbonate resin molded article comprising the polycarbonate resin.

A third aspect of the present disclosure is directed to a film composed of the above polycarbonate resin.

A fourth aspect of the present disclosure is directed to a retardation film composed of the above film.

A fifth aspect of the present disclosure is directed to a circularly polarizing plate including the above-described retardation film.

A sixth aspect of the present disclosure is directed to an image display device including the circular changing piece.

A seventh aspect of the present disclosure is directed to a method for producing a transparent film, wherein, in the method for producing a transparent film by molding the polycarbonate resin by a melt film-forming method,

The polycarbonate resin is molded at a molding temperature of 280 ℃ or lower.

An eighth aspect of the present disclosure is directed to a polycarbonate resin comprising:

a structural unit (A) represented by the above formula (1) and/or the above formula (2), and

A structural unit (B) represented by the above formula (3),

The glass transition temperature of the polycarbonate resin is 120 ℃ to 160 ℃,

The water absorption of the polycarbonate resin is 1.4% or less.

Effects of the invention

As described above, the polycarbonate resin has a specific structural unit having an oligofluorene structure and a specific copolymerization component. Therefore, the polycarbonate resin is excellent in optical characteristics and also has high wet heat resistance. In addition, the polycarbonate resin is excellent in mechanical properties such as toughness and melt processability.

Further, the polycarbonate resin molded article, film, retardation film, and circularly polarizing plate comprising the polycarbonate resin have high wet heat resistance and excellent optical properties and mechanical properties. Further, since the image display device includes the circularly polarizing plate, the image display device can be suitably used for a flexible display, a vehicle-mounted display requiring high wet heat resistance, and the like.

In the above production method, the polycarbonate resin is molded by a melt film-forming method at a molding temperature of 280 ℃ or lower. This enables to produce a transparent film having excellent mechanical properties such as toughness and optical properties and high wet heat resistance.

Detailed Description

The following describes embodiments of the present invention in detail, but the description of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention is not limited to the following unless the gist thereof is exceeded. In the present specification, the term "structural unit" refers to a partial structure of a polymer sandwiched between adjacent linking groups, and a partial structure sandwiched between a polymerization-reactive group present in a terminal portion of the polymer and a linking group adjacent to the polymerization-reactive group. In the present specification, the term "to" is used in a sense including numerical values and physical values described before and after the term. The numerical values or physical values described as the upper limit and the lower limit are used in the meaning of including the values. Unless otherwise specified, "%" means "% by weight". The terms "part by weight" and "part by weight", "wt%" and "wt%" are substantially the same as each other.

In the present disclosure, the polycarbonate resin is a concept including not only a polycarbonate resin but also a polyester carbonate resin. The polyester carbonate resin refers to a polymer in which structural units constituting the polymer contain not only carbonate linkages but also moieties linked by ester linkages.

In the present specification, the term "to" is used to include values before and after the term "to" when used in the description of numerical values or physical property values.

The polycarbonate resin is composed of at least a structural unit (A), a structural unit (B) and a structural unit (C), and has a plurality of these structural units in a polymer chain. The polycarbonate resin is, for example, a random copolymer. The structural unit (a) is represented by the following formula (1) and/or the following formula (2). That is, the polycarbonate resin has a structural unit represented by formula (1) and/or a structural unit represented by formula (2) as the structural unit (a). The structural unit (B) is represented by the following formula (3). The structural unit (C) is a structural unit derived from a dihydroxy compound having an acetal ring structure. The acetal ring structure is also referred to as a cyclic acetal structure.

[ Chemical 4]

[ Chemical 5]

In the formulas (1) and (2), R ¹～R³ is independently an alkylene group having 1 to 4 carbon atoms which is directly bonded, substituted or unsubstituted. R ⁴～R⁹ is independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted acyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 2 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 2 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group or a cyano group. R ⁴～R⁹ may be the same as or different from each other, and at least two adjacent groups in R ⁴～R⁹ may be bonded to each other to form a ring.

[ Chemical 6]

In the formula (3), R ¹⁰～R¹⁷ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. X ¹ represents a direct bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.

[ Structure and raw Material of polycarbonate resin ]

< Oligofluorene structural unit >

The polycarbonate resin contains a structural unit (a) composed of a structural unit represented by the following formula (1) and/or a structural unit represented by the following formula (2). Hereinafter, this structural unit may be referred to as an "oligofluorene structural unit".

[ Chemical 7]

[ Chemical 8]

In the formulas (1) and (2), R ¹～R³ each independently represents a directly bonded, substituted or unsubstituted alkylene group having 1 to 4 carbon atoms. R ⁴～R⁹ is independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted acyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 2 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 2 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group or a cyano group. Wherein R ⁴～R⁹ may be the same as or different from each other, and at least two adjacent groups in R ⁴～R⁹ may be bonded to each other to form a ring. The polycarbonate resin preferably contains a structural unit represented by formula (2) from the viewpoint of easily orienting the fluorene ring in the polymer perpendicularly to the main chain direction and exhibiting stronger reverse wavelength dispersion.

As R ¹ and R ², for example, the following alkylene groups can be used. Specific examples include: straight-chain alkylene groups such as methylene, ethylene, n-propylene, n-butylene, and the like; and branched alkylene groups such as methyl methylene, dimethyl methylene, ethyl methylene, propyl methylene, (1-methylethyl) methylene, 1-methylethylene, 2-methylethylene, 1-ethylethylene, 2-ethylethylene, 1-methylpropylene, 2-methylpropylene, 1-dimethylethylene, 2-dimethylpropylene, and 3-methylpropylene. Here, the positions of the branches in R ¹ and R ² are indicated by numbers given so that the carbon atom on the fluorene ring side becomes the 1-position. In addition, R ¹ and R ² are preferably ethylene groups, from the viewpoint of easily orienting fluorene rings in the polymer perpendicularly to the main chain direction and exhibiting stronger reverse wavelength dispersion.

The choice of R ¹ and R ² can be related to the behavior of the inverse dispersive wavelength dependence. The polycarbonate resin exhibits the strongest inverse dispersion wavelength dependence in a state where the fluorene ring is oriented perpendicularly to the main chain direction (stretching direction). In order to bring the orientation state of the fluorene ring close to such a state and to exhibit a strong inverse dispersion wavelength dependence, R ¹ and R ² having 2 to 3 carbon atoms in the main chain of the alkylene group are preferably used. When the number of carbon atoms is 1, the inverse dispersion wavelength dependence may not be unexpectedly exhibited. The reason for this is considered that, for example, the orientation of the fluorene ring is immobilized in a direction not perpendicular to the main chain direction due to steric hindrance of the carbonate group and/or the ester group as the linking group of the oligofluorene structural unit. On the other hand, when the number of carbon atoms is too large, the fixation of the orientation of the fluorene ring becomes weak, and thus the inverse dispersion wavelength dependence may become insufficient. Further, the heat resistance of the polycarbonate resin may be lowered.

As R ³, for example, the following alkylene groups can be used. Specific examples include: straight-chain alkylene groups such as methylene, ethylene, n-propylene, n-butylene, and the like; and branched alkylene groups such as methyl methylene, dimethyl methylene, ethyl methylene, propyl methylene, (1-methylethyl) methylene, 1-methylethylene, 2-methylethylene, 1-ethylethylene, 2-ethylethylene, 1-methylpropylene, 2-methylpropylene, 1-dimethylethylene, 2-dimethylpropylene, and 3-methylpropylene. R ³ is preferably 1 to 2 carbon atoms in the main chain of the alkylene group, more preferably 1 carbon atom. When the number of carbon atoms in the main chain is too large, immobilization of the fluorene ring may be weakened, and there is a possibility that the inverse dispersion wavelength dependence may be reduced, the photoelastic coefficient may be increased, the heat resistance may be reduced, or the like, as in the case of R ¹ and R ². On the other hand, when the number of carbon atoms in the main chain is small, optical characteristics and heat resistance are good, but when the 9-positions of the two fluorene rings are connected by direct bonding, thermal stability may be deteriorated.

Examples of the substituent for R ¹～R³ include: halogen atoms (specifically fluorine atoms, chlorine atoms, bromine atoms, or iodine atoms); alkoxy groups having 1 to 10 carbon atoms such as methoxy and ethoxy; acyl groups having 1 to 10 carbon atoms such as acetyl and benzoyl; an acylamino group having 1 to 10 carbon atoms such as an acetamido group and a benzamido group; a nitro group; cyano group; aryl groups having 6 to 10 carbon atoms such as phenyl and naphthyl groups. 1 to 3 hydrogen atoms in the aryl group may be substituted with the above-mentioned halogen atom, alkoxy group, acyl group, acylamino group, nitro group, cyano group, or the like.

As the substituted or unsubstituted alkyl group in R ⁴～R⁹, for example, the following alkyl groups can be used. Specific examples include: straight-chain alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, and n-decyl; alkyl groups having a branched chain such as isopropyl group, 2-methylpropyl group, 2-dimethylpropyl group, and 2-ethylhexyl group; cyclic alkyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, and cyclooctyl. The number of carbon atoms of the alkyl group is preferably 4 or less, more preferably 2 or less. When the number of carbon atoms is within this range, steric hindrance between fluorene rings is less likely to occur, and desired optical characteristics derived from fluorene rings are easily obtained. Examples of the substituent for the alkyl group include the substituents described above for R ¹～R³.

As the substituted or unsubstituted aryl group in R ⁴～R⁹, for example, the following aryl groups can be used. Specific examples include: aryl groups such as phenyl, 1-naphthyl and 2-naphthyl; heteroaryl groups such as 2-pyridyl, 2-thienyl, 2-furyl, and the like. The number of carbon atoms of the aryl group is preferably 8 or less, more preferably 7 or less. When the number of carbon atoms is within this range, steric hindrance between fluorene rings is less likely to occur, and desired optical characteristics derived from fluorene rings are easily obtained. Examples of the substituent for the aryl group include the substituents described above for R ¹～R³.

As the substituted or unsubstituted acyl group in R ⁴～R⁹, for example, the following acyl group can be used. Specific examples include: aliphatic acyl groups such as formyl, acetyl, propionyl, 2-methylpropanoyl, 2-dimethylpropionyl and 2-ethylhexanoyl; aromatic acyl groups such as benzoyl, 1-naphthylcarbonyl, 2-naphthylcarbonyl and 2-furylcarbonyl. The number of carbon atoms of the acyl group is preferably 4 or less, more preferably 2 or less. When the number of carbon atoms is within this range, steric hindrance between fluorene rings is less likely to occur, and desired optical characteristics derived from fluorene rings are easily obtained. Examples of the substituent for the acyl group include the substituent described above for R ¹～R³.

As the substituted or unsubstituted alkoxy or aryloxy group in R ⁴～R⁹, for example, the following groups can be used. Specific examples include: methoxy, ethoxy, isopropoxy, tert-butoxy, trifluoromethoxy, phenoxy. The number of carbon atoms of the alkoxy group or the aryloxy group is preferably 4 or less, more preferably 2 or less. When the number of carbon atoms is within this range, steric hindrance between fluorene rings is less likely to occur, and desired optical characteristics derived from fluorene rings are easily obtained. Examples of the substituent for the alkoxy group or the aryloxy group include the substituents described above for R ¹～R³.

As the substituted or unsubstituted amino group in R ⁴～R⁹, for example, the following amino groups can be used. Specific examples include: an amino group; aliphatic amino groups such as N-methylamino, N-dimethylamino, N-ethylamino, N-diethylamino, N-methylethylamino, N-propylamino, N-dipropylamino, N-isopropylamino, N-diisopropylamino and the like; an aromatic amino group such as an N-phenylamino group or an N, N-diphenylamino group; acylamino groups such as carboxamide, acetamido, decanoylamino, benzamido, chloroacetamido and the like; alkoxycarbonylamino groups such as benzyloxycarbonylamino and t-butoxycarbonylamino. The amino group is preferably an N, N-dimethylamino group, an N-ethylamino group or an N, N-diethylamino group, more preferably an N, N-dimethylamino group. In this case, the amino group does not have a proton having a high acidity, and the molecular weight of the amino group is small, so that the fluorene ratio can be improved. Therefore, in addition to improving the thermal stability, the amount of the monomer having an oligofluorene structural unit can be reduced.

As the substituted or unsubstituted vinyl group or acetylene group in R ⁴～R⁹, for example, the following groups can be used. Specific examples include: vinyl, 2-methylethenyl, 2-dimethylvinyl, 2-phenylvinyl, 2-acetylvinyl, ethynyl, methylethynyl, t-butylethynyl, phenylethynyl, acetylethynyl, trimethylsilylethynyl. The number of carbon atoms of the vinyl group or the acetylene group is preferably 4 or less. When the number of carbon atoms is within this range, steric hindrance between fluorene rings is less likely to occur, and desired optical characteristics derived from fluorene rings are easily obtained. Further, a longer conjugated system of fluorene ring makes it easy to obtain a stronger inverse dispersion wavelength dependence.

As the sulfur atom having a substituent in R ⁴～R⁹, for example, the following sulfur-containing groups can be used. Specific examples include:

A sulfo group; alkylsulfonyl groups such as methylsulfonyl, ethylsulfonyl, propylsulfonyl and isopropylsulfonyl; arylsulfonyl groups such as phenylsulfonyl and p-tolylsulfonyl; alkylsulfinyl groups such as methylsulfinyl, ethylsulfinyl, propylsulfinyl and isopropylsulfinyl; arylsulfinyl groups such as phenylsulfinyl and p-tolylsulfinyl; alkylthio groups such as methylthio and ethylthio; arylthio groups such as phenylthio and p-tolylthio; an alkoxysulfonyl group such as a methoxysulfonyl group or an ethoxysulfonyl group; aryloxy sulfonyl groups such as phenoxy sulfonyl; an aminosulfonyl group; alkylsulfonyl groups such as N-methylaminosulfonyl group, N-ethylaminosulfonyl group, N-t-butylaminosulfonyl group, N-dimethylaminosulfonyl group, and N, N-diethylaminosulfonyl group; aryl aminosulfonyl such as N-phenyl aminosulfonyl and N, N-diphenyl aminosulfonyl. The sulfo group may be salified with lithium, sodium, potassium, magnesium, ammonium, or the like. The sulfur-containing group is preferably a methylsulfinyl group, an ethylsulfinyl group or a phenylsulfinyl group, and more preferably a methylsulfinyl group. In this case, the sulfur-containing group does not have a proton having a high acidity, and the molecular weight of the sulfur-containing group is small, so that the fluorene ratio can be improved. Therefore, in addition to improving the thermal stability, the amount of the monomer having an oligofluorene structural unit can be reduced.

As the silicon atom having a substituent in R ⁴～R⁹, for example, the following silyl group can be used. Specific examples include: trialkylsilyl groups such as trimethylsilyl and triethylsilyl; trimethoxysilyl, triethoxysilyl, and other trialkoxysilyl groups. Trialkylsilyl groups are preferred. Because of excellent stability and operability.

In addition, as the halogen atom in R ⁴～R⁹, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom can be used. Among these, fluorine atom, chlorine atom or bromine atom is preferable, and fluorine atom or bromine atom is more preferable, because it is relatively easy to introduce and has a tendency to increase the reactivity of fluorene at 9 position due to electron withdrawing property.

Specific examples of the ring formed by bonding at least two adjacent groups in R ⁴～R⁹ to each other include substituted fluorene structures shown in the following group [ I ]. In the following group [ I ], the wavy line indicates that the bond from the 9-position of the fluorene structure to R ¹ and R ² or R ² and R ³ is omitted in the figure.

[ Chemical 9]

The content of the structural unit (a) is preferably 1 mass% or more, more preferably 3 mass% or more, still more preferably 5 mass% or more, particularly preferably 7 mass% or more, and most preferably 10 mass% or more, relative to 100 mass% of the total of all structural units and linking groups constituting the polycarbonate resin, from the viewpoint that the wavelength dispersion of the polycarbonate resin can be adjusted to a desired range and the mechanical properties are improved. Further, in addition to the decrease in the photoelastic coefficient of the polycarbonate resin, it is expected that the expression of the retardation will be improved, and the content of the structural unit (a) is preferably 45 mass% or less, more preferably 40 mass% or less, still more preferably 35 mass% or less, and particularly preferably 30 mass% or less, from the viewpoint that the proportion of the structural unit (a) in the resin can be reduced to widen the molecular design range and to facilitate improvement when the resin is required to be modified. Specifically, the linking group is a carbonate group or an ester group present at the end of each structural unit. The content of the structural unit (a) is the total content of the structural unit represented by the formula (1) and the structural unit represented by the formula (2), and when only any one of the structural units is contained, the content of the other structural unit is 0.

Examples of the method for adjusting the ratio of the oligofluorene structural unit in the resin include: a method of copolymerizing a monomer having an oligofluorene structural unit with other monomers, and a method of blending a resin containing an oligofluorene structural unit with other resins. From the viewpoint that the content of the oligofluorene structural unit can be precisely controlled, and that high transparency can be obtained, and that uniform characteristics can be obtained over the entire surface of the film, a method of copolymerizing a monomer having an oligofluorene structural unit with other monomers is preferable.

The polycarbonate resin contains a structural unit (B) represented by the following formula (3).

[ Chemical 10]

In the above formula (3), R ¹⁰～R¹⁷ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. X ¹ represents a direct bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. In the case where X ¹ in the formula (3) is a divalent hydrocarbon group having 1 to 20 carbon atoms, the hydrocarbon group is preferably a substituted or unsubstituted chain alkylene group having 1 to 20 carbon atoms, a substituted or unsubstituted cyclic alkylene group having 6 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a fluorenylene group having 13 to 20 carbon atoms. In this case, the effects of improving heat resistance and reducing water absorption can be obtained.

As the chain alkylene group, the cyclic alkylene group, examples thereof include ：-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-CH(Ph)-、-C(CH₃)Ph-、-CPh₂-、1,2- ethylene, 1, 3-propylene, 1, 4-butylene, 1-propylene, 1-cyclobutylene, 1-cyclopentylene, 1-cyclohexylene, 3, 5-trimethyl-1, 1-cyclohexylene 1, 1-cyclododecyl, 1, 2-cyclopropyl, 1, 2-cyclobutyl, 1, 2-cyclopentyl, 1, 2-cyclohexyl, 1, 3-cyclobutyl, 1, 3-cyclopentyl, 1, 3-cyclohexyl, 1, 4-cyclohexyl and the like. Here Ph is unsubstituted phenyl.

Examples of the arylene group include: 1, 2-phenylene, 1, 3-phenylene, 1, 4-phenylene.

Examples of the fluorenylene group include: 9, 9-fluorenylene.

In the case where X ₁ is a divalent hydrocarbon group having 1 to 20 carbon atoms, the bonding position on the benzene ring in the above formula (3) may be any of the 2,2' -position, 2,3' -position, 2,4' -position, 3' -position, 3,4' -position, and 4,4' -position, but is preferably the 4,4' -position. In this case, the mechanical properties are further improved.

On the other hand, in the case where X ¹ is a direct bond, the biphenyl skeleton in the above formula (3) may be any one of a 2,2' -biphenyl skeleton, 2,3' -biphenyl skeleton, 2,4' -biphenyl skeleton, 3' -biphenyl skeleton, 3,4' -biphenyl skeleton, 4' -biphenyl skeleton, but is preferably a 4,4' -biphenyl skeleton.

From the viewpoint of further improving the wet heat resistance of the polycarbonate resin, X ₁ as the formula (3) is more preferably -CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-CH(Ph)-、-C(CH₃)Ph-、-CPh₂-、9,9- fluorenylene, 1-cyclohexylene, 3, 5-trimethyl-1, 1-cyclohexylene, 1-cyclododecylene.

In the above formula (3), R ¹⁰～R¹⁷ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group.

The substituted or unsubstituted alkyl group having 1 to 20 carbon atoms may be any of a straight chain, a branched chain, and a cyclic group, and may have a substituent such as a phenyl group.

For example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, cyclopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, cycloheptyl, methylcyclohexyl, n-octyl, cyclooctyl, n-nonyl, 3, 5-trimethylcyclohexyl, n-decyl, cyclodecyl, n-undecyl, n-dodecyl, cyclododecyl, benzyl, methylbenzyl, dimethylbenzyl, trimethylbenzyl, naphthylmethyl, phenethyl, 2-phenylisopropyl and the like.

Examples of the substituted or unsubstituted aryl group include phenyl, naphthyl, and the like which may have a substituent such as an alkyl group, such as phenyl, o-tolyl, m-tolyl, p-tolyl, ethylphenyl, styryl, xylyl, n-propylphenyl, isopropylphenyl, trimethylphenyl, ethynylphenyl, naphthyl, and vinylnaphthyl.

R ¹⁰～R¹⁷ is more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, particularly preferably a hydrogen atom or a methyl group.

Examples of the dihydroxy compound (i.e., dihydroxy compound constituting the structural unit (B)) which is a source of the structural unit (B) include: 2, 2-bis (4-hydroxyphenyl) propane, 2-bis (3-methyl-4-hydroxyphenyl) propane, 2-bis (4-hydroxy-3, 5-dimethylphenyl) propane, 2-bis (4-hydroxy-3, 5-diethylphenyl) propane 2, 2-bis (4-hydroxy- (3-phenyl) propane, 2-bis (4-hydroxy- (3, 5-diphenyl) phenyl) propane, 2-bis (4-hydroxy-3, 5-dibromophenyl) propane, bis (4-hydroxyphenyl) methane, 1-bis (4-hydroxyphenyl) ethane 2, 2-bis (4-hydroxyphenyl) butane, 2-bis (4-hydroxyphenyl) pentane, 1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 1-bis (4-hydroxyphenyl) -2-ethylhexane, 1-bis (4-hydroxyphenyl) decane, bis (4-hydroxy-3-nitrophenyl) methane, 3-bis (4-hydroxyphenyl) pentane, 1, 3-bis (2- (4-hydroxyphenyl) -2-propyl) benzene, 1, 3-bis (2- (4-hydroxyphenyl) -2-propyl) benzene, 2-bis (4-hydroxyphenyl) hexafluoropropane, 1-bis (4-hydroxyphenyl) cyclohexane, 4' - (cyclododecane-1, 1-diyl) bisphenol aromatic bisphenol compounds such as1, 1-bis (4-hydroxyphenyl) -3, 5-trimethylcyclohexane, 4' - (cyclododecane-1, 1-diyl) bisphenol, and 4,4' - (α -methylbenzylidene) bisphenol; dihydroxy compounds having an ether group bonded to an aromatic group, such as2, 2-bis (4- (2-hydroxyethoxy) phenyl) propane, 2-bis (4- (2-hydroxypropoxy) phenyl) propane, and 4,4' -bis (2-hydroxyethoxy) biphenyl; 9, 9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9-bis (4-hydroxyphenyl) fluorene, 9-bis (4-hydroxy-3-methylphenyl) fluorene, 9-bis (4- (2-hydroxypropoxy) phenyl) fluorene 9, 9-bis (4- (2-hydroxyethoxy) -3-methylphenyl) fluorene, 9-bis (4- (2-hydroxypropoxy) -3-methylphenyl) fluorene, 9-bis (4- (2-hydroxyethoxy) -3-isopropylphenyl) fluorene 9, 9-bis (4- (2-hydroxyethoxy) -3-isobutylphenyl) fluorene, 9-bis (4- (2-hydroxyethoxy) -3-tert-butylphenyl) fluorene, 9-bis (4- (2-hydroxyethoxy) -3-cyclohexylphenyl) fluorene, 9-bis (4- (2-hydroxyethoxy) -3-phenylphenyl) fluorene, 9-bis (4- (2-hydroxyethoxy) -3, 5-dimethylphenyl) fluorene, 9-bis (4- (2-hydroxyethoxy) -3-tert-butyl-6-methylphenyl) fluorene, dihydroxy compounds having a fluorene ring such as 9, 9-bis (4- (3-hydroxy-2, 2-dimethylpropoxy) phenyl) fluorene. The dihydroxy compound which is the source of the structural unit (B) is preferably 2, 2-bis (4-hydroxy-3, 5-dimethylphenyl) propane, 1-bis (4-hydroxyphenyl) cyclohexane, 4' - (cyclododecane-1, 1-diyl) bisphenol 1, 1-bis (4-hydroxyphenyl) -3, 5-trimethylcyclohexane, 4' - (cyclododecane-1, 1-diyl) bisphenol, 4' - (α -methylbenzylidene) bisphenol, 9-bis (4-hydroxy-3-methylphenyl) fluorene.

Particularly suitable specific examples of the structural unit (B) are represented by the following formulas (6) to (11). The structural unit (B) preferably contains at least one selected from the group consisting of the following formulas (6) to (11), more preferably contains at least one selected from the group consisting of the following formulas (8) to (11), even more preferably contains the following formula (8) and/or the following formula (9), and most preferably the following formula (8). In this case, even when the content of the structural unit (B) in the polycarbonate resin is small, the heat resistance of the resin can be improved, and the water absorption can be reduced. That is, heat resistance can be effectively improved and water absorption can be effectively reduced. Further, in this case, the photoelastic coefficient of the polycarbonate resin can be reduced, and the mechanical properties of the polymer are also good.

[ Chemical 11]

[ Chemical 12]

[ Chemical 13]

[ Chemical 14]

[ 15]

[ 16]

From the viewpoint of improving the heat resistance and water absorption of the polycarbonate resin and improving the mechanical properties, the content of the structural unit (B) is preferably 5 mass% or more, more preferably 10 mass% or more, still more preferably 15 mass% or more, still more preferably 20 mass% or more, and most preferably 25 mass% or more, relative to 100 mass% of the total of all the structural units and the linking groups constituting the polycarbonate resin. The content of the structural unit (B) is preferably 50 mass% or less, more preferably 45 mass% or less, further preferably 40 mass% or less, and particularly preferably 35 mass% or less, from the viewpoint of being able to reduce the photoelastic coefficient of the polycarbonate resin.

The polycarbonate resin contains a structural unit (C) derived from a dihydroxy compound having an acetal ring structure. As the dihydroxy compound having an acetal ring structure, for example, dioxane diol represented by the following formula (13) and/or spiro diol represented by the formula (14) can be used.

[ Chemical 17]

[ Chemical 18]

Preferably, the structural unit (C) is a structural unit derived from a spiroglycol represented by the formula (14). In this case, the heat resistance of the polycarbonate resin can be improved, and the photoelastic coefficient can be further reduced.

The content of the structural unit (C) is preferably 15 mass% or more, more preferably 20 mass% or more, still more preferably 25 mass% or more, and particularly preferably 30 mass% or more, relative to 100 mass% of the total of all structural units and linking groups constituting the polycarbonate resin, from the viewpoint that the balance of physical properties such as heat resistance and optical properties can be adjusted without significantly impairing the excellent properties of the polycarbonate resin. From the same viewpoint, the content of the structural unit (C) is preferably 75 mass% or less, more preferably 70 mass% or less, further preferably 65 mass% or less, and particularly preferably 60 mass% or less.

The polycarbonate resin may further contain a structural unit (D) derived from at least one compound selected from the group consisting of aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, oxyalkylene glycols and dihydroxy compounds having a heterocyclic structure. The structural unit (D) is a structural unit other than the structural units (a) to (C), and may have a heterocyclic structure, for example, but does not include an acetal ring structure. From the viewpoint of further improving the mechanical properties of the polycarbonate resin, the structural unit (D) is preferably a structural unit derived from at least one compound selected from the group consisting of an aliphatic dihydroxy compound, an alicyclic dihydroxy compound, and a dihydroxy compound having a heterocyclic structure other than an acetal ring structure.

Examples of the aliphatic dihydroxy compound include: branched aliphatic dihydroxy compounds such as ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 2-pentanediol, 1, 3-pentanediol, 1, 4-pentanediol, 1, 5-pentanediol, 1, 2-hexanediol, 1, 3-hexanediol, 1, 4-hexanediol, 1, 5-hexanediol, 1, 6-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 11-undecanediol, 1, 12-dodecanediol, neopentyl glycol, 2-ethyl-1, 6-hexanediol, 2, 4-trimethyl-1, 6-hexanediol, hydrogenated dioleyl glycol and the like. Among these, preferred are linear aliphatic dihydroxy compounds such as ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 11-undecanediol, and 1, 12-dodecanediol from the viewpoint of easiness of obtaining and easiness of handling.

Examples of the alicyclic dihydroxy compound include the following dihydroxy compounds. Specific examples include: examples of the dihydroxy compound of the primary alcohol of the alicyclic hydrocarbon include dihydroxy compounds derived from terpene compounds such as 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, 2, 6-decalin dimethanol, 1, 5-decalin dimethanol, 2, 3-norbornane dimethanol, 2, 5-norbornane dimethanol, 1, 3-adamantane dimethanol, and limonene; examples of the dihydroxy compound of the secondary or tertiary alcohol of the alicyclic hydrocarbon include 1, 2-cyclohexanediol, 1, 4-cyclohexanediol, 1, 3-adamantanediol, hydrogenated bisphenol A, and 2, 4-tetramethyl-1, 3-cyclobutanediol.

As the oxyalkylene glycol, for example, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like can be used.

Examples of the dihydroxy compound having a heterocyclic structure include dihydroxy compounds represented by the following formula (12).

[ Chemical 19]

Examples of the dihydroxy compound represented by formula (12) include isosorbide, isomannide, isoidide (isoidide) having a stereoisomeric relationship. Among these dihydroxy compounds (12), isosorbide obtained by dehydration condensation of sorbitol produced from various starches is most preferred in terms of ease of acquisition and production and formability, since it is readily available as a resource. These dihydroxy compounds (12) may be used singly or in combination of two or more.

The structural unit (D) is preferably a structural unit derived from a compound of formula (12). In this case, the effect of improving the heat resistance and improving the polymerization reactivity can be obtained.

In addition, from the viewpoint of easily obtaining a balance of heat resistance, optical characteristics, mechanical properties, and polymerization reactivity, it is preferable that the structural unit (C) is a structural unit derived from the compound of formula (14), and the structural unit (D) is a structural unit derived from the compound of formula (12). The structural unit derived from the compound represented by the formula (14) is represented by the following formula (4), and the structural unit derived from the compound represented by the formula (12) is represented by the following formula (5).

[ Chemical 20]

[ Chemical 21]

The above-mentioned at least one compound selected from the group consisting of aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, oxyalkylene glycols and dihydroxy compounds having a heterocyclic structure is preferably 1, 6-hexanediol, 2, 4-tetramethyl-1, 3-cyclobutanediol, 1, 4-cyclohexanedimethanol, tricyclodecanedimethanol, isosorbide, dioxane glycol, spiroglycol, particularly preferably isosorbide and spiroglycol. Polycarbonate resins containing structural units derived from these monomers are more excellent in balance of optical properties, heat resistance, mechanical properties, and the like.

From the viewpoint of being able to adjust the balance of physical properties such as heat resistance and optical properties without significantly impairing the excellent properties of the polycarbonate resin, the total content of the structural units (C) and the structural units (D) is preferably 20 mass% or more, more preferably 25 mass% or more, still more preferably 30 mass% or more, and particularly preferably 35 mass% or more, relative to 100 mass% of the total of all the structural units and the linking groups constituting the polycarbonate resin. From the same viewpoint, the total content of the structural units (C) and (D) is preferably 80 mass% or less, more preferably 75 mass% or less, further preferably 70 mass% or less, and particularly preferably 65 mass% or less.

< Carbonic acid diester >

The linking group of the above-mentioned structural unit contained in the polycarbonate resin can be introduced by polymerizing a carbonic acid diester represented by the following formula (15).

[ Chemical 22]

In the formula (15), R ¹⁸ and R ¹⁹ are each an aliphatic hydrocarbon group having 1 to 18 carbon atoms which may be substituted or an aromatic hydrocarbon group having 6 to 10 carbon atoms which may be substituted, and R ¹⁸ and R ¹⁹ may be the same or different.

R ¹⁸ and R ¹⁹ are preferably substituted or unsubstituted aromatic hydrocarbon groups, more preferably unsubstituted aromatic hydrocarbon groups. Examples of the substituent for the aliphatic hydrocarbon group include: examples of the substituent for the aromatic hydrocarbon group include an ester group, an ether group, an amide group, and a halogen atom: alkyl groups such as methyl and ethyl.

As the carbonic acid diester represented by the above formula (15), for example, there can be exemplified: substituted diphenyl carbonate such as diphenyl carbonate (hereinafter also abbreviated as DPC) and xylene carbonate, and dialkyl carbonates such as dimethyl carbonate, diethyl carbonate and di-t-butyl carbonate, but preferably diphenyl carbonate and substituted diphenyl carbonate, particularly preferably diphenyl carbonate.

The carbonic acid diester may contain impurities such as chloride ions, and these impurities may inhibit polymerization reaction or deteriorate the color of the obtained resin, and therefore, if necessary, it is preferable to use a carbonic acid diester purified by distillation or the like.

[ Physical Properties of polycarbonate resin ]

The polycarbonate resin preferably has the following physical properties.

(Glass transition temperature)

The glass transition temperature of the polycarbonate resin is preferably 120℃or higher, more preferably 125℃or higher, and still more preferably 130℃or higher. When the glass transition temperature is not less than the lower limit, sufficient heat resistance can be obtained. The glass transition temperature of the polycarbonate resin is preferably 160℃or lower, more preferably 155℃or lower, and further preferably 150℃or lower. When the glass transition temperature is equal to or lower than the upper limit, the melt processability is improved. The glass transition temperature of the polycarbonate resin can be measured by the method described in examples. The glass transition temperature of the polycarbonate resin is appropriately adjusted, for example, by changing the kind and ratio of the structural units constituting the resin.

(Water absorption)

The water absorption of the polycarbonate resin is preferably 1.4% or less, more preferably 1.3% or less, further preferably 1.2% or less, particularly preferably 1.1% or less, and most preferably 1.0% or less. When the water absorption is not more than the upper limit, the dimensional change rate in the hot and humid environment is sufficiently reduced. Therefore, when the phase difference film made of polycarbonate resin is used in a display device, for example, it is possible to suppress the change of display characteristics with time. The water absorption of the polycarbonate resin can be measured by the method described later. The water absorption of the polycarbonate resin can be appropriately adjusted by changing the kind and ratio of the structural units constituting the resin, for example.

(Photoelastic coefficient)

The polycarbonate resin is preferably 25×10 ^-12 Pa or less, more preferably 22×10 ^-12 Pa or less, still more preferably 19×10 ^-12 Pa or less, still more preferably 16×10 ^-12 Pa or less, particularly preferably 15×10 ^-12 Pa or less, and most preferably 14×10 ^-12 Pa or less. When the photoelastic coefficient is equal to or less than the upper limit, sufficient environmental reliability (visibility does not change depending on the use environment) can be obtained when the polycarbonate resin is used as a retardation film. This characteristic is important particularly when used in a large display device or flexible display under high-temperature and high-humidity environments.

In the polycarbonate resin, the photoelastic coefficient can be suppressed to be lower by reducing the content of the structural unit (a) represented by the above formula (1) or (2) and the structural unit (B) represented by the above formula (3).

[ Conditions for producing polycarbonate resin ]

The polycarbonate resin can be produced by a polymerization method generally employed. For example, the following method may be used for manufacturing: solution polymerization or interfacial polymerization using phosgene, carboxylic acid halides; a melt polymerization method in which a reaction is performed without using a solvent. Among these production methods, a melt polymerization method is preferable, which can reduce environmental load by not using a solvent or a highly toxic compound, and which is also excellent in productivity.

When a solvent is used in the polymerization, there is a case where the solvent remains in the polycarbonate resin, and the plasticizing effect thereof lowers the glass transition temperature of the polycarbonate resin, which may cause quality change in the processing steps such as molding and stretching described later. In addition, although a halogen-based organic solvent such as methylene chloride is often used as the solvent, when the halogen-based solvent remains in the polycarbonate resin, the molded article using the resin may cause corrosion when it is assembled into an electronic device. Since the polycarbonate resin obtained by the melt polymerization method does not contain a solvent, it is also advantageous for stabilization of the processing steps and the product quality.

When a polycarbonate resin is produced by melt polymerization, a monomer having the above-mentioned structural unit, a carbonic acid diester, and a polymerization catalyst are mixed and subjected to transesterification (or also referred to as polycondensation) under melting, whereby the reaction rate is improved while removing the released component from the system. In the final stage of polymerization, the reaction is carried out under high temperature, high vacuum conditions until the target molecular weight is reached. After the reaction, the polycarbonate resin in a molten state was withdrawn from the reactor. Thus, a polycarbonate resin was obtained.

The polycondensation reaction can be controlled in reaction rate and molecular weight of the obtained polycarbonate resin by strictly adjusting the molar ratio of all the dihydroxy compounds to all the diester compounds used in the reaction. In the case of the polycarbonate resin, the molar ratio of the carbonic acid diester to the total dihydroxy compounds is preferably adjusted to 0.90 to 1.10, more preferably 0.96 to 1.08, and particularly preferably 0.98 to 1.06. In the case of the polyester carbonate resin, the molar ratio of the total amount of the carbonic acid diester and the total amount of the diester compounds to the total amount of the dihydroxy compounds is preferably adjusted to 0.90 to 1.10, more preferably to 0.96 to 1.08, and particularly preferably to 0.98 to 1.06.

If the above molar ratio varies greatly, a resin having a desired molecular weight cannot be produced. When the molar ratio is too small, the hydroxyl group end of the produced resin may increase, and the thermal stability of the resin may be deteriorated. In addition, many unreacted dihydroxy compounds remain in the polycarbonate resin, which may cause contamination of molding machines and poor appearance of molded articles in the subsequent molding step. On the other hand, when the molar ratio is too large, the rate of transesterification reaction is decreased under the same conditions, or the residual amount of the carbonic acid diester and diester compound in the produced polycarbonate resin is increased, and thus the residual low-molecular component similarly causes a problem in the molding step.

The melt polymerization method is generally carried out in a multi-step process of two or more steps. The polycondensation reaction may be carried out by using 1 polymerization reactor, changing the sequential conditions and performing two or more steps, or may be carried out by using 2 or more reactors, changing the respective conditions and performing two or more steps, but from the viewpoint of production efficiency, it is carried out by using 2 or more, preferably 3 or more reactors. The polycondensation reaction may be any of batch type, continuous type, or a combination of batch type and continuous type, but is preferably continuous type from the viewpoints of production efficiency and quality stability.

In the polycondensation reaction, it is important to appropriately control the balance between the temperature and the pressure in the reaction system. When either the temperature or the pressure is changed too quickly, unreacted monomers may be distilled out of the reaction system. As a result, the molar ratio of the dihydroxy compound to the diester compound may be changed, and a polycarbonate resin having a desired molecular weight may not be obtained.

In addition, the polymerization rate of the polycondensation reaction can be controlled according to the balance of the hydroxyl group terminal and the ester group terminal or the carbonate group terminal. Therefore, particularly in the case of continuous polymerization, when the balance of the terminal groups is changed by distillation of the unreacted monomers, it is difficult to control the polymerization rate to be constant, and there is a possibility that the molecular weight of the obtained polycarbonate resin is changed to be large. Since the molecular weight of the polycarbonate resin is related to the melt viscosity, there is a possibility that the melt viscosity fluctuates during molding of the obtained polycarbonate resin, and a molded article of a uniform size may not be obtained.

Further, when the unreacted monomer is distilled off, not only the balance of the terminal groups but also the copolymerization composition of the polycarbonate resin may deviate from the desired composition, and there is a possibility that the mechanical properties and optical properties may be affected. In the retardation film, since the wavelength dispersibility of the retardation is controlled by the ratio of the fluorene monomer to other copolymerization components in the polycarbonate resin, when the ratio is unbalanced during polymerization, there is a possibility that the designed optical characteristics cannot be obtained.

Hereinafter, the melt polycondensation step will be described in the following stages: a stage of consuming the monomer and forming the oligomer, and a stage of allowing the polymerization to proceed until a desired molecular weight is reached to form a polymer.

Specifically, as reaction conditions in the first-stage reaction, the following conditions may be employed. That is, the internal temperature of the polymerization reactor is set in the following range: typically 130 ℃ or higher, preferably 150 ℃ or higher, more preferably 170 ℃ or higher, and typically 250 ℃ or lower, preferably 240 ℃ or lower, more preferably 230 ℃ or lower. In addition, the pressure of the polymerization reactor was set in the following range: the pressure is usually 70kPa or less (hereinafter, the pressure means absolute pressure), preferably 50kPa or less, more preferably 30kPa or less, and is usually 1kPa or more, preferably 3kPa or more, more preferably 5kPa or more. In addition, the reaction time was set in the following range: usually 0.1 hour or more, preferably 0.5 hour or more, and usually 10 hours or less, preferably 5 hours or less, more preferably 3 hours or less.

The reaction in the first stage may be carried out while distilling off the produced monohydroxy compound derived from the diester compound to the outside of the reaction system. For example, in the case where diphenyl carbonate is used as the carbonic acid diester, the monohydroxy compound distilled off to the outside of the reaction system in the reaction of the first stage is phenol. In the reaction in the first stage, the polymerization reaction is promoted as the reaction pressure is lowered, but the distillation of the unreacted monomer is increased. In order to achieve both of suppression of distillation of unreacted monomers and promotion of reaction by reduced pressure, it is effective to use a reactor equipped with a reflux condenser. In particular, a reflux condenser is preferably used at the initial stage of the reaction where the amount of unreacted monomers is large.

The second-stage reaction gradually decreases the pressure of the reaction system from the pressure of the first step, excludes the monohydroxy compound produced in succession from the reaction system, and finally sets the pressure of the reaction system to 5kPa or less, preferably 3kPa or less, more preferably 1kPa or less. Further, the internal temperature is set in the following range: usually at a temperature of 210℃or higher, preferably 220℃or higher, and usually 270℃or lower, preferably 260℃or lower. In addition, the reaction time was set in the following range: the time is usually 0.1 hours or more, preferably 0.5 hours or more, more preferably 1 hour or more, and is usually 10 hours or less, preferably 5 hours or less, more preferably 3 hours or less. In order to suppress coloring and thermal degradation and obtain a polycarbonate resin having good hue and thermal stability, the maximum internal temperature in the whole reaction stage may be 270 ℃ or less, preferably 265 ℃ or less, and more preferably 260 ℃ or less.

The transesterification catalyst (hereinafter also simply referred to as "catalyst" or "polymerization catalyst") that can be used in polymerization has a great influence on the reaction rate, the color tone and the thermal stability of the polycarbonate resin obtained by polycondensation. The catalyst that can be used is not particularly limited as long as it can give satisfactory transparency, hue, heat resistance, thermal stability and mechanical strength to the polycarbonate resin produced, and examples thereof include: basic compounds such as metal compounds of group 1 or group 2 (hereinafter also abbreviated as "group 1" and "group 2") in the long-form periodic table, basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds. It is preferable to use at least one metal compound selected from the group consisting of metals of group 2 of the long form periodic table and lithium.

As the group 1 metal compound, for example, the following compounds may be used, but other group 1 metal compounds may be used. Sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, cesium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium acetate, potassium acetate, lithium acetate, cesium acetate, sodium stearate, potassium stearate, lithium stearate, cesium stearate, sodium borohydride, potassium borohydride, lithium borohydride, cesium borohydride, sodium tetraphenylborate, potassium tetraphenylborate, lithium tetraphenylborate, cesium tetraphenylborate, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, dipotassium hydrogen phosphate, disodium phenyl phosphate, dipotassium phenyl phosphate, dipcaesium phenyl phosphate, sodium, potassium, lithium, cesium alkoxides, phenolates, disodium salts of bisphenol a, dipotassium salts, dilithium salts, and cesium salts. Among these, a lithium compound is preferably used from the viewpoints of polymerization activity and hue of the obtained polycarbonate resin.

As the group 2 metal compound, for example, the following compounds may be used, but other group 2 metal compounds may be used. Calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium bicarbonate, magnesium bicarbonate, strontium bicarbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate. Among these, magnesium compounds, calcium compounds, and barium compounds are preferably used, and from the viewpoints of polymerization activity and hue of the obtained polycarbonate resin, magnesium compounds and/or calcium compounds are more preferably used, and calcium compounds are most preferably used.

The above-mentioned group 1 metal compound and/or group 2 metal compound may be used in combination with an alkaline compound such as an alkaline boron compound, an alkaline phosphorus compound, an alkaline ammonium compound, or an amine compound, but it is particularly preferable to use at least one metal compound selected from the group consisting of a metal of group 2 of the long-form periodic table and lithium.

The amount of the polymerization catalyst is usually 0.1. Mu. Mol to 300. Mu. Mol, preferably 0.5. Mu. Mol to 100. Mu. Mol, based on 1mol of the total dihydroxy compound used in the polymerization. When at least one metal compound selected from the group consisting of a metal of group 2 of the long form periodic table and lithium is used as the polymerization catalyst, particularly when a magnesium compound and/or a calcium compound is used, the polymerization catalyst is usually used in an amount of 1.0. Mu. Mol or more, preferably 5.0. Mu. Mol or more, and particularly preferably 10. Mu. Mol or more, based on 1mol of the total dihydroxy compounds. The amount of the polymerization catalyst is usually 300. Mu. Mol or less, preferably 200. Mu. Mol or less, and particularly preferably 100. Mu. Mol or less.

In the case of producing a polyester carbonate resin using a diester compound as a monomer, a transesterification catalyst such as a titanium compound, a tin compound, a germanium compound, an antimony compound, a zirconium compound, a lead compound, an osmium compound, a zinc compound, or a manganese compound may be used in combination with or without the above-mentioned basic compound. The amount of the transesterification catalyst used is usually in the range of 1. Mu. Mol to 1mmol, preferably 5. Mu. Mol to 800. Mu. Mol, and particularly preferably 10. Mu. Mol to 500. Mu. Mol, based on 1mol of the total dihydroxy compound used in the reaction, based on the metal amount.

When the amount of the catalyst is too small, the polymerization rate becomes low, and therefore the polymerization temperature has to be increased by a corresponding amount in order to obtain a polycarbonate resin of a desired molecular weight. Therefore, there is a possibility that the hue of the obtained polycarbonate resin is deteriorated and the unreacted raw material volatilizes during the polymerization to unbalance the molar ratio of the dihydroxy compound to the diester compound, thereby failing to achieve the desired molecular weight. On the other hand, when the amount of the polymerization catalyst is too large, undesired side reactions occur at the same time, which may deteriorate the hue of the obtained polycarbonate resin and may cause coloration and decomposition of the polycarbonate resin during molding.

When sodium, potassium, and cesium are contained in a large amount in the polycarbonate resin, the hue may be adversely affected by the group 1 metal. These metals may be mixed not only from the catalyst used but also from the raw materials and the reaction apparatus. The total amount of the compounds of these metals in the polycarbonate resin may be 2. Mu. Mol or less, preferably 1. Mu. Mol or less, and more preferably 0.5. Mu. Mol or less, based on 1mol of the total dihydroxy compounds.

After the polymerization, the polycarbonate resin is usually cooled and solidified, and pelletized by a rotary cutter or the like. The granulation method is not limited, and examples thereof include: a method of drawing out the polymer in a molten state from the polymerization reactor in the final stage, cooling and solidifying the polymer in the form of strands, and granulating the polymer; a method in which a polycarbonate resin is fed from a polymerization reactor in the final stage to a single-screw or twin-screw extruder in a molten state, and is melt-extruded, cooled, solidified, and pelletized; or a method in which the polycarbonate resin is fed again to a single-screw or twin-screw extruder after being withdrawn from the polymerization reactor in the final stage in a molten state, cooled and solidified in the form of strands, and pelletized.

Since the polycarbonate resin is suitable for optical applications, it is preferable that the content of foreign matters in the polycarbonate resin is small. In order to remove foreign matters such as scorch and gel in the polycarbonate resin obtained by melt polycondensation, filtration is preferably performed using a filter. Among them, in order to remove residual monomers, by-product phenol, and the like by devolatilization under reduced pressure and to mix additives such as a heat stabilizer, a mold release agent, and the like, it is preferable to melt-extrude a polycarbonate resin by the above-mentioned vented twin-screw extruder and then filter the resin by a filter.

As the form of the filter, a known filter such as a candle type filter, a pleated type filter, a disc type filter, or the like can be used. The pore diameter of the filter is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 20 μm or less, as a filtration accuracy of 99%. In particular, when it is intended to reduce foreign matter, the pore diameter of the filter is preferably 10 μm or less, but when the pore diameter is reduced, the pressure loss in the filter increases, which may cause breakage of the filter or deterioration of the polycarbonate resin due to heat generation by shearing, and therefore, the filter accuracy is preferably 1 μm or more as 99%. The pore size of the filter described herein is determined in accordance with ISO 16889.

The polycarbonate resin filtered by the filter is discharged from the die in the form of strands, cooled and solidified, and pelletized by a rotary cutter or the like, but in the case of strand formation and pelletization of the polycarbonate resin in direct contact with the outside air, it is preferable to carry out the resin in a clean room having a purity of grade 7 defined in JIS B9920:2002, more preferably higher than grade 6, in order to prevent the contamination of foreign matter from the outside air.

In the granulation, it is preferable to use a cooling method such as air cooling or water cooling, and it is desirable to use air in which foreign matter in the air is removed in advance by a HEPA filter or the like as the air used in the air cooling, so that reattachment of the foreign matter in the air is prevented. When water cooling is used, it is preferable to remove metal components in water by ion exchange resin or the like, and further, water from which foreign substances in water have been removed by a filter is used. The pore size of the water filter to be used is preferably 10 to 0.45 μm as a filtration accuracy of 99% removal.

[ Additive ]

The polycarbonate resin may further contain a heat stabilizer, an antioxidant, a catalyst deactivator, an ultraviolet absorber, a light stabilizer, a mold release agent, a dye pigment, an impact modifier, an antistatic agent, a sliding agent, a lubricant, a plasticizer, a compatibilizer, a nucleating agent, a flame retardant, an inorganic filler, a foaming agent, and the like which are generally used within a range not impairing the object of the present invention.

(Heat stabilizer)

If necessary, a heat stabilizer may be added to the polycarbonate resin to prevent a decrease in molecular weight and a decrease in hue during melt processing. Examples of such heat stabilizers include generally known hindered phenol heat stabilizers and/or phosphorus heat stabilizers.

As the hindered phenol compound, for example, the following compounds can be used. 2, 6-di-tert-butylphenol, 2, 4-di-tert-butylphenol, 2-tert-butyl-4-methoxyphenol, 2-tert-butyl-4, 6-dimethylphenol, 2, 6-di-tert-butyl-4-methylphenol, 2, 6-di-tert-butyl-4-ethylphenol, 2, 5-di-tert-butylhydroquinone, n-octadecyl-3- (3 ',5' -di-tert-butyl-4 '-hydroxyphenyl) propionate, 2-tert-butyl-6- (3' -tert-butyl-5 '-methyl-2' -hydroxybenzyl) -4-methylphenyl propionate, 2 '-methylene-bis- (4-methyl-6-tert-butylphenol), 2' -methylene-bis- (6-cyclohexyl-4-methylphenol), 2 '-ethylidene-bis- (2, 4-di-tert-butylphenol), tetrakis- [ methylene-3- (3', 5 '-di-tert-butyl-4' -hydroxyphenyl) propionate ] -methane, 1,3, 5-trimethyl-2, 4, 6-tris- (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene and the like. Among them, tetrakis- [ methylene-3- (3 ',5' -di-t-butyl-4 '-hydroxyphenyl) propionate ] -methane, n-octadecyl-3- (3', 5 '-di-t-butyl-4' -hydroxyphenyl) propionate, and 1,3, 5-trimethyl-2, 4, 6-tris- (3, 5-di-t-butyl-4-hydroxybenzyl) benzene are preferably used.

As the phosphorus compound, for example, phosphorous acid, phosphoric acid, phosphonic acid, esters thereof, and the like shown below can be used, but phosphorus compounds other than these compounds may also be used. Triphenyl phosphite, tris (nonylphenyl) phosphite, tris (2, 4-di-tert-butylphenyl) phosphite, tridecyl phosphite, trioctyl phosphite, trioctadecyl phosphite, didecyl monophenyl phosphite, dioctyl monophenyl phosphite, diisopropylmonophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyldiphenyl phosphite, bis (2, 6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, 2-methylenebis (4, 6-di-tert-butylphenyl) octyl phosphite bis (nonylphenyl) pentaerythritol diphosphite, bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tributyl phosphate, triethyl phosphate, trimethyl phosphate, triphenyl phosphate, diphenyl mono-o-hexenyl phosphate, dibutyl phosphate, dioctyl phosphate, diisopropyl phosphate, tetra (2, 4-di-tert-butylphenyl) 4,4' -biphenylene diphosphonate, dimethyl phenylphosphonate, diethyl phenylphosphonate, dipropyl phenylphosphonate. One kind of these heat stabilizers may be used alone, or two or more kinds may be used in combination.

Such a heat stabilizer may be added to the reaction liquid at the time of melt polymerization, or may be added to a polycarbonate resin by using an extruder and kneaded. In the case of producing a film by melt extrusion, the film may be produced by adding the heat stabilizer or the like to an extruder, or the heat stabilizer may be added to a polycarbonate resin in advance by using an extruder to form a shape such as pellets.

The amount of the heat stabilizer to be added is preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more, further preferably 0.001 parts by mass or more, and further preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, further preferably 2.0 parts by mass or less, based on 100 parts by mass of the polycarbonate resin.

(Catalyst deactivator)

The color tone and thermal stability can be improved by adding an acidic compound to the polycarbonate resin for neutralizing and inactivating the catalyst used in the polymerization reaction. As the acidic compound used as the catalyst deactivator, a compound having a carboxylic acid group, a phosphoric acid group, a sulfonic acid group, or an ester thereof, or the like can be used, but particularly, a phosphorus compound having a partial structure represented by the following formula (16) or (17) is preferably used.

[ Chemical 23]

[ Chemical 24]

The phosphorus compound represented by the above formula (16) or (17) may be: phosphoric acid, phosphorous acid, phosphonic acid, hypophosphorous acid, polyphosphoric acid, phosphonates, acid phosphates, and the like. Among the above, phosphorous acid, phosphonic acid, and phosphonate are more excellent in the effect of catalyst deactivation and coloring inhibition, and phosphorous acid is particularly preferable. The phosphonic acid may be: phosphonic acid (phosphorous acid), methylphosphonic acid, ethylphosphonic acid, vinylphosphonic acid, decylphosphonic acid, phenylphosphonic acid, benzylphosphonic acid, aminomethylphosphonic acid, methylenediphosphonic acid, 1-hydroxyethane-1, 1-diphosphonic acid, 4-methoxyphenylphosphonic acid, nitrilotris (methylenephosphonic acid), propylphosphonic acid, and the like.

Examples of the phosphonate include: dimethyl phosphonate, diethyl phosphonate, bis (2-ethylhexyl) phosphonate, dilauryl phosphonate, dioleyl phosphonate, diphenyl phosphonate, dibenzyl phosphonate, dimethyl methylphosphonate, diphenyl methylphosphonate, diethyl ethylphosphonate, diethyl benzylphosphonate, dimethyl phenylphosphonate, diethyl phenylphosphonate, dipropyl phenylphosphonate, (methoxymethyl) diethyl phosphonate, diethyl vinylphosphonate, diethyl hydroxymethylphosphonate, (2-hydroxyethyl) dimethyl phosphonate, diethyl p-methylbenzylphosphonate, diethyl phosphorylacetic acid, t-butyl diethylphosphorylacetic acid, (4-chlorobenzyl) diethyl phosphonate, diethyl cyanophosphonate, diethyl cyanomethylphosphonate, diethyl 3, 5-di-t-butyl-4-hydroxybenzyl phosphonate, diethyl phosphorylacetaldehyde diethyl acetal, (methylthiomethyl) phosphonate, and the like.

Examples of the acid phosphate include: dimethyl phosphate, diethyl phosphate, divinyl phosphate, dipropyl phosphate, dibutyl phosphate, bis (butoxyethyl) phosphate, bis (2-ethylhexyl) phosphate, diisotridecyl phosphate, dioleyl phosphate, distearyl phosphate, diphenyl phosphate, dibenzyl phosphate and other phosphoric acid diesters or mixtures of diesters and monoesters, diethyl chlorophosphate, zinc salts of stearyl phosphate and the like.

These may be used alone or in combination of two or more in any combination and ratio.

When the amount of the phosphorus compound added to the polycarbonate resin is too small, the effects of catalyst deactivation and coloring inhibition are insufficient, and when too large, the polycarbonate resin is colored, and particularly in a durability test in high temperature and high humidity, the polycarbonate resin becomes easy to be colored. The amount of the phosphorus compound to be added is an amount corresponding to the amount of the catalyst to be used in the polymerization reaction. The amount of the phosphorus compound is preferably 0.5 to 5 times by mol, more preferably 0.7 to 4 times by mol, particularly preferably 0.8 to 3 times by mol, based on 1mol of the metal of the catalyst used in the polymerization reaction.

(Polymer alloy)

For the purpose of modifying the mechanical properties, solvent resistance and other properties, one or more of synthetic resins such AS aromatic polycarbonate, aromatic polyester, aliphatic polyester, polyamide, polystyrene, polyolefin, acrylic, amorphous polyolefin, ABS, AS, polylactic acid, polybutylene succinate and the like, rubber, elastomer and the like may be kneaded with the above polycarbonate resin to prepare a polymer alloy.

The above-mentioned additives and modifiers can be produced by mixing the above-mentioned components in the polycarbonate resin simultaneously or in any order by a mixer such as a roll, a V-type mixer, a Norta mixer, a Banbury mixer, a kneading roll, or an extruder, and kneading by an extruder, particularly a twin-screw extruder is preferable from the viewpoint of improving dispersibility.

[ Method for producing retardation film ]

(Method for producing unstretched film)

As a method for producing an unstretched film using a polycarbonate resin, the following method can be adopted: a casting method of removing a solvent after dissolving a polycarbonate resin in the solvent and casting; a melt film-forming method for forming a film by melting a polycarbonate resin without using a solvent. The melt film-forming method specifically includes a melt extrusion method using a T-die, a calender molding method, a hot press method, a coextrusion method, a eutectic melting method, a multilayer extrusion method, a blow molding method, and the like. The film forming method of the unstretched film is not particularly limited, but a melt film forming method is preferable because a problem due to a residual solvent may occur in the casting method, and among them, a melt extrusion method using a T-die is preferable from the viewpoint of easiness of a subsequent stretching process.

When an unstretched film is formed by the melt film forming method, the forming temperature is preferably 280℃or lower, more preferably 270℃or lower, and particularly preferably 265℃or lower. When the molding temperature is too high, foreign matter and bubbles may be generated in the obtained film, causing an increase in defects or coloring of the film. However, when the molding temperature is too low, the melt viscosity of the polycarbonate resin becomes too high, and thus the molding of the rolled film becomes difficult, and it may be difficult to produce an unstretched film having a uniform thickness, and therefore the lower limit of the molding temperature is usually 200 ℃, preferably 210 ℃, more preferably 220 ℃. The molding temperature of the unstretched film is a temperature at the time of molding in the melt film-forming method, and is usually a value obtained by measuring the temperature of the polycarbonate resin at the die outlet from which the melt polycarbonate resin is extruded.

In addition, when a foreign matter is present in the film, it is recognized as a defect such as light leakage when it is used as a polarizing plate. In order to remove foreign matters in the polycarbonate resin, the following method is preferable: after the extruder, a polymer filter was attached, and after the polycarbonate resin was filtered, it was extruded from a die to form a film. In this case, it is necessary to connect the extruder, the polymer filter, and the mold with pipes to transfer the molten polycarbonate resin, but it is important to arrange each equipment so that the residence time is minimized in order to suppress thermal degradation in the pipes as much as possible. Further, it is required to pay attention to the steps of carrying and winding the extruded film in a clean room so that foreign matters do not adhere to the film.

The thickness of the unstretched film depends on the design of the film thickness of the stretched retardation film, stretching conditions such as stretching ratio, but when too thick, thickness unevenness tends to occur, and when too thin, breakage during conveyance and stretching tends to occur, and therefore, it is usually 30 μm or more, preferably 40 μm or more, more preferably 50 μm or more, and further, it is usually 200 μm or less, preferably 160 μm or less, more preferably 120 μm or less. Further, when there is a variation in thickness of the unstretched film, the retardation of the retardation film is not uniform, and therefore the thickness of the portion used as the retardation film is preferably set to be not more than ±3 μm, more preferably not more than ±2 μm, and particularly preferably not more than ±1 μm.

The length of the unstretched film in the longitudinal direction is preferably 500m or more, more preferably 1000m or more, and particularly preferably 1500m or more. From the viewpoint of productivity and quality, continuous stretching is preferable when producing a retardation film, but in general, it is necessary to perform condition adjustment so as to meet a predetermined retardation at the start of stretching, and when the film length is too short, the amount of product that can be obtained after the condition adjustment decreases. In the present specification, the term "long" means that the film has a dimension in the longitudinal direction sufficiently larger than a dimension in the width direction, and substantially means that the film can be wound in a coil shape in the longitudinal direction. More specifically, the film has a length dimension that is 10 times or more greater than a width dimension.

The internal haze of the unstretched film obtained as described above is preferably 3% or less, more preferably 2% or less, and particularly preferably 1% or less. When the internal haze of the unstretched film is larger than the upper limit value, scattering of light may occur, and for example, when the film is laminated with a polarizer, polarization elimination may occur. The lower limit of the internal haze is not particularly limited, but is usually 0.1%. The internal haze was measured as follows: the adhesive transparent film having been subjected to haze measurement in advance was bonded to both sides of the unstretched film, and a sample having been subjected to external haze influence eliminated was used, and the haze value of the adhesive transparent film was subtracted from the measured value of the sample to obtain an internal haze value.

(Method for producing retardation film)

By stretching and orienting the unstretched film, a retardation film can be obtained. As the stretching method, a known method such as longitudinal uniaxial stretching, transverse uniaxial stretching using a tenter or the like, simultaneous biaxial stretching in which these are combined, and stepwise biaxial stretching can be used. The stretching may be performed in a batch manner, but is preferably performed continuously from the viewpoint of productivity. Further, a retardation film having less variation in retardation in the film plane can be obtained by continuous stretching as compared with the intermittent stretching.

The stretching temperature is in the range of (Tg-20 ℃) to (Tg+30 ℃) with respect to the glass transition temperature (Tg) of the polycarbonate resin used as the raw material, preferably in the range of (Tg-10 ℃) to (Tg+20 ℃) and more preferably in the range of (Tg-5 ℃) to (Tg+15 ℃). The stretching ratio may be determined according to the target phase difference value, and may be 1.2 to 4 times, more preferably 1.5 to 3.5 times, still more preferably 2 to 3 times, in the longitudinal direction and the transverse direction, respectively. When the stretch ratio is too small, the effective range in which the desired degree of orientation and orientation angle can be obtained becomes narrow. On the other hand, when the stretch ratio is too large, the film may break or wrinkle during stretching.

The stretching speed may be appropriately selected according to the purpose, and may be selected as follows: the strain rate meter expressed by the following expression is usually 50 to 2000%/min, preferably 100 to 1500%/min, more preferably 200 to 1000%/min, and particularly preferably 250 to 500%/min. If the stretching speed is too high, breakage during stretching or a long-term use under high temperature conditions may occur, which may increase the fluctuation of optical characteristics. Further, if the stretching speed is too small, productivity may be lowered, and the stretching ratio may have to be excessively increased to obtain a desired retardation.

Strain rate (%/min) = { stretching rate (mm/min)/length of rolled film (mm) } ×100

After stretching the film, the film may be heat-set by a heating furnace as needed, or may be relaxed by controlling the width of the tenter or adjusting the peripheral speed of the rolls. The heat-setting treatment is carried out at a temperature in the range of 60℃to (Tg), preferably 70℃to (Tg-5 ℃) relative to the glass transition temperature (Tg) of the polycarbonate resin used in the unstretched film. If the heat treatment temperature is too high, the orientation of the molecules obtained by stretching becomes random, and the retardation may be significantly reduced from that of the desired retardation. In addition, in the case of providing the relaxation step, by contracting the film width expanded by stretching to 95% to 99%, the stress generated in the stretched film can be eliminated. At this time, the treatment temperature applied to the film is the same as the heat-setting treatment temperature. By performing the heat setting treatment and the relaxation step as described above, it is possible to suppress variation in optical characteristics due to long-term use under high-temperature conditions.

The retardation film can be produced by appropriately selecting and adjusting the processing conditions in such a stretching step. The birefringence (. DELTA.n) of the retardation film in the plane at a wavelength of 550nm is preferably 0.001 or more, more preferably 0.0012 or more, particularly preferably 0.0015 or more. Since the phase difference is proportional to the film thickness (d) and the birefringence (Δn), by setting the birefringence within the above specific range, a desired phase difference can be exhibited with a small film thickness, and a film suitable for a thin device can be easily produced. In order to exhibit high birefringence, it is necessary to increase the degree of orientation of polymer molecules by lowering the stretching temperature, increasing the stretching ratio, and the like, but the film is likely to break under such stretching conditions, so that the polycarbonate resin used is more advantageous as the toughness is more excellent. Specifically, the higher the toughness of the film, the more the fracture of the nip portion at the time of the film stretching process can be suppressed, for example. In addition, when the toughness is high, folding bending, and winding of the film are possible, and the film can be applied to folding applications, bending applications, and winding applications. In particular, the film is suitable as a component of a flexible display.

The thickness of the retardation film is also in accordance with the design value of the retardation, but is preferably 110 μm or less. The thickness of the retardation film is more preferably 105 μm or less, still more preferably 100 μm or less, and particularly preferably 95 μm or less. On the other hand, when the thickness is too small, handling of the film becomes difficult, wrinkles or breaks occur during production, and therefore the lower limit of the thickness of the retardation film is preferably 10 μm, more preferably 15 μm.

The ratio of the retardation (R450) measured at a wavelength of 450nm to the retardation (R550) measured at a wavelength of 550nm, that is, the value of the wavelength dispersion (R450/R550), of the retardation film is preferably 0.60 or more and 1.00 or less, more preferably 0.70 or more and 0.95 or less, and particularly preferably 0.80 or more and 0.90 or less. If the value of the above-mentioned wavelength dispersion is within this range, it is possible to obtain an ideal phase difference characteristic in a wide wavelength range in the visible light region. For example, a polarizing plate and a display device having a small wavelength dependence of hue can be realized by manufacturing a retardation film having such wavelength dependence as a 1/4 wave plate and bonding the retardation film to a polarizing plate to manufacture a circular polarizing plate or the like. On the other hand, when the ratio is outside the above range, the wavelength dependence of the hue increases, and optical compensation cannot be achieved at all wavelengths in the visible light range, which causes problems such as coloration and contrast reduction due to light penetration into the polarizer and the display device.

The retardation film is laminated with a known polarizing film, and cut into a desired size to obtain a circularly polarizing plate. Such a circularly polarizing plate is used for, for example, a viewing angle compensation application for various displays (liquid crystal display device, organic EL display device, plasma display device, FED field emission display device, SED surface electric field display device), an application for preventing reflection of external light, a color compensation application, a conversion application of linearly polarized light to circularly polarized light, and the like.

Examples

Examples of the polycarbonate copolymer are shown below, but are not limited thereto as long as they do not exceed the gist thereof. The various production conditions and evaluation results in the examples below have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention, and preferable ranges may be ranges defined by combinations of the values of the upper limit or the lower limit and the values of the examples or the values of the examples.

The measurement method and evaluation method of each physical property and characteristic are as follows.

(A) Glass transition temperature

The glass transition temperature of the resin was measured using a differential scanning calorimeter DSC6220 manufactured by Seiko electronic nanotechnology (SII NanoTechnology). About 10mg of the resin sample was placed in an aluminum tray manufactured by this company and sealed, and the temperature was raised from 30℃to 200℃at a heating rate of 20℃per minute under a nitrogen gas stream of 50 mL/min. After maintaining the temperature for 3 minutes, it was cooled to 30℃at a rate of 20℃per minute. The temperature was maintained at 30℃for 3 minutes and again raised to 200℃at a rate of 20℃per minute. From DSC data obtained during the 2 nd temperature rise, an extrapolated glass transition start temperature, which is a temperature at which an intersection point between a straight line extending a base line on a low temperature side to a high temperature side and a tangent line drawn at a point where a slope of a curve of a stepwise change portion of the glass transition reaches a maximum, is obtained, and the temperature is set as a glass transition temperature.

(B) Determination of Water absorption

The polycarbonate resin pellets are dried at 100 ℃ under reduced pressure of 200Pa or less for 12 hours or more. Next, about 4g of the dried pellets were subjected to a small-sized hot press (ASONE, AH-2003C AH-1 TC), a separator having a length of 14cm, a width of 14cm and a thickness of 0.1mm was used, polyimide films were laid on the upper and lower sides of the sample, preheated at a temperature of 200 to 230℃for 3 minutes, pressurized at a pressure of 7MPa for 5 minutes, and then taken out together with the separator, and cooled to prepare a film.

The obtained film was cut into squares having a length of 100mm and a width of 100mm to prepare a sample. The sample was dried at a temperature of-10 ℃ and a glass transition temperature under reduced pressure of 200Pa or less for 24 hours or more. The mass of the dried sample was quantified to 0.1mg, and this value was taken as the dry mass. Then, the dried sample was immersed in desalted water at a temperature of 23℃for 72 hours or more. The immersed sample was taken out of the water, and the surface was wiped with a clean and dry cloth or filter paper to measure the water content to 0.1mg, and the water absorption quality was defined as the value. The water uptake mass was taken out of the water and measured within 1 minute. The water absorption was determined using equation 1.

(Water absorption mass-dry mass)/dry mass×100=water absorption (%) … … … formula 1

(C) Reduction viscosity of resin

The resin was dissolved in methylene chloride to prepare a resin solution having a concentration of 0.6 g/dL. The solvent passage time t ₀ and the solution passage time t were measured by using a Ubbelohde viscosity tube manufactured by Send chemical industry Co., ltd at a temperature of 20.0.+ -. 0.1 ℃. Using the obtained values of t ₀ and t, the relative viscosity η _rel was obtained according to the following formula (I), and further using the obtained relative viscosity η _rel, the specific viscosity η _sp was obtained according to the following formula (ii).

η_rel＝t/t₀…(I)

η_sp＝(η-η₀)/η₀＝η_rel-1…(ii)

Then, the specific viscosity η _sp obtained was divided by the concentration c (g/dL) to obtain the reduction viscosity η _sp/c. The higher the value, the greater the molecular weight.

< Evaluation of unstretched film >

(D) Forming of unstretched films

The polycarbonate resin pellets are dried at 100 ℃ under reduced pressure of 200Pa or less for 12 hours or more. Next, about 4g of the dried pellets were subjected to a small-sized hot press (ASONE, AH-2003C AH-1 TC), a separator having a length of 14cm, a width of 14cm and a thickness of 0.1mm was used, polyimide films were laid on the upper and lower sides of the test piece, preheated at 200 to 230℃for 3 minutes, pressurized at a pressure of 7MPa for 5 minutes, and then taken out together with the separator, and cooled to prepare an unstretched film.

(E) Determination of the photoelastic coefficient

The measurement was performed using a combination of a birefringence measurement device comprising a He-Ne laser, a polarizer, a compensation plate, an analyzer, and a photodetector, and a dynamic viscoelasticity measurement device (DVE-3 manufactured by Rheology). (refer specifically to Japanese society of rheology Vol.19, p93-97 (1991))

Test pieces 20mm long and 5mm wide were cut out from the unstretched film, and the pieces were fixed to a viscoelasticity measuring apparatus, and the storage modulus E' was measured at a frequency of 96Hz at room temperature of 25 ℃. At the same time, the emitted laser light is sequentially passed through a polarizer, a sample, a compensation plate, and an analyzer, picked up by a photodetector (photodiode), passed through a phase-locked amplifier, and then subjected to a waveform of angular frequency ω or 2ω, and the amplitude and phase difference with respect to strain are obtained, thereby obtaining a strain optical coefficient O'. At this time, the polarizer and the analyzer were adjusted so that the polarizer were perpendicular to each other and each had an angle of pi/4 with respect to the direction of elongation of the sample. The photoelastic coefficient C was obtained using the storage modulus E 'and the strain optical coefficient O', and was obtained according to the following equation.

C＝O’/E’

In the following examples and comparative examples, the evaluation that the photoelastic coefficient was 19×10 ^-12Pa^-1 or less was excellent with little change in optical characteristics due to film expansion and contraction caused by change in the use environment.

(F) Toughness of film (bending test)

By the above method, an unstretched film having a thickness of 100 to 200 μm was produced, and a rectangular test piece having a length of 40mm and a width of 10mm was produced from the film. The left and right joint surfaces of the clamps were spaced apart by 40mm, and both ends of the test piece were fixed to the joint surfaces. Next, the distance between the left and right joining surfaces is narrowed at a speed of 2 mm/sec or less, and the whole of the film bent in a substantially U-shape is compressed in the joining surface while the film is not protruded beyond the joining surface of the clip. The case where the test piece was broken into 2 pieces (or 3 pieces or more pieces of pieces) at the bent portion before the joint surfaces were completely adhered was regarded as "cracked", and the case where the test piece was bent without being broken although the joint surfaces were completely adhered was regarded as "no crack". The test was repeated 5 times for the same type of film, wherein the evaluation of "cracking" for 3 or more times was "x: brittle failure occurred, "the evaluation of" cracking "was" o "for 2 or less times: no brittle failure "and the evaluation of no brittle failure was made as excellent in toughness.

(G) Moist heat resistance test (high Pressure Cooking (PCT) test)

The unstretched film was subjected to steam treatment at 110℃under 0.15MPa, 100% RH for 24 hours using a laboratory autoclave (LSX-300) manufactured by TOMYS Seiko, and the change in film shape or the presence or absence of whitening before and after the test was confirmed.

< Evaluation >

And (2) the following steps: no opaque portion at all, or only a portion thereof;

X: the whole is opaque.

< Evaluation of retardation film >

(H) Stretching of films

A film sheet having a width of 50mm and a length of 125mm was cut from the unstretched film, and the free end of the film sheet was uniaxially stretched using a batch biaxial stretching apparatus (biaxial stretching apparatus BIX-277-AL manufactured by Island industries Co.) at a stretching temperature of +15℃, a stretching speed of 300%/min and a stretching ratio of 1.5 times to obtain a stretched film.

(I) Retardation, wavelength dispersion, and birefringence of stretched films

The stretched film obtained by the above method was cut at the center thereof to have a width of 4cm and a length of 4cm, and a retardation was measured at measurement wavelengths of 450, 500, 550, 590, and 630nm using a retardation measuring device KOBA-WPR manufactured by prince measuring instruments Co. Wavelength dispersibility is expressed as the ratio of the phase difference R450 to R550 (R450/R550) measured at 450nm and 550 nm. When R450/R550 is larger than 1, the wavelength dispersion becomes positive, and when it is smaller than 1, the reverse wavelength dispersion becomes. In the case of a 1/4 wave plate, the ideal value for R450/R550 is 0.818 (450/550=0.818).

The birefringence Δn can be obtained from the following equation using the retardation R550 at 550nm and the thickness of the stretched film. The larger the value of birefringence=r550 [ nm ]/(film thickness [ mm ] ×10 ⁶) is, the higher the degree of orientation of the polymer is. Further, the larger the value of birefringence, the thinner the film thickness for obtaining a desired phase difference value can be.

[ Raw materials used ]

Abbreviations and manufacturers of the compounds used in the following examples and manufacturing examples are shown below.

[ Monomer ]

SPG: spirocyclic diols (Mitsubishi gas chemical company)

ISB: isosorbide (Roquette Freres company)

PEG-1000: polyethylene glycol (Sanyang chemical industry Co., ltd.)

BP-TMC:1, 1-bis (4-hydroxyphenyl) -3, 5-trimethylcyclohexane (manufactured by Benzhou chemical Co., ltd.) BisP-CDE:4,4' - (cyclododecane-1, 1-diyl) bisphenol (manufactured by Benzhou chemical Co., ltd.)

BCF:9, 9-bis (4-hydroxy-2-methylphenyl) fluorene (manufactured by Benzhou chemical Co., ltd.)

BisP-AP:4,4' - (α -methylbenzylidene) bisphenol (manufactured by Benzhou chemical Co., ltd.)

BHEPF:9, 9-bis [4- (2-hydroxyethoxy) phenyl ] fluorene (manufactured by Benzhou chemical Co., ltd.)

SBI:6,6' -dihydroxy-3, 3' -tetramethyl-1, 1' -spiroindane

The synthesis was carried out according to the method described in paragraph [0264] of Japanese patent application laid-open No. 2014-114281.

[ Chemical 25]

BPFM: bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl ] methane

The synthesis was carried out according to the method described in paragraph [0596] of Japanese patent application laid-open No. 2015-25111.

[ Chemical 26]

DPC: diphenyl carbonate (Mitsubishi chemical corporation)

Example 1

The raw materials were charged so that the content of each structural unit was the values shown in Table 1. Specifically, 30.20 parts by mass (0.097 mol) of BP-TMC, 37.77 parts by mass (0.124 mol) of SPG, BPFM 39.47.47 parts by mass (0.062 mol), 35.41 parts by mass (0.165 mol) of DPC and 1.17X10- ^-2 parts by mass (6.64X10- ^-5 mol) of calcium acetate monohydrate as a catalyst were charged into a reaction vessel, and the inside of the reaction vessel was subjected to nitrogen substitution under reduced pressure. The raw materials were dissolved while stirring for about 10 minutes at 150℃under nitrogen atmosphere. As a step of the first stage of the reaction, the temperature was raised to 220℃over 30 minutes, and the reaction was carried out at normal pressure for 60 minutes. Then, the pressure was reduced from normal pressure to 13.3kPa for 90 minutes, and the reaction system was purged with the produced phenol after maintaining at 13.3kPa for 30 minutes. Next, as a step of the second stage of the reaction, the temperature of the heating medium was raised to 260℃for 15 minutes, and at the same time, the pressure was reduced to 0.10kPa or less for 15 minutes, whereby the produced phenol was withdrawn out of the reaction system. After a predetermined stirring torque was reached, the reaction was terminated by returning the pressure to normal pressure with nitrogen gas, and the resultant polyester carbonate was extruded into water and strands were cut to obtain pellets. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3. In table 1, the charge of the raw material is expressed in mol%, and in table 2, the charge of the raw material is expressed in mass%.

Example 2

Pellets of a polyester carbonate were obtained in the same manner as in example 1 except that 30.20 parts by mass (0.097 mol), 39.50 parts by mass (0.130 mol) of SPG, BPFM 36.65.65 parts by mass (0.057 mol), 37.60 parts by mass (0.176 mol) of DPC and 1.20X10- ^-2 parts by mass (6.81X 10 ^-5 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 3

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that 30.20 parts by mass (0.097 mol) of BP-TMC, 41.23 parts by mass (0.135 mol) of SPG, BPFM 33.83 parts by mass (0.053 mol) of DPC 39.79 parts by mass (0.186 mol) and 1.23X10- ^-2 parts by mass (6.98X10- ^-5 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The evaluation results are shown in tables 1 to 3.

Example 4

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that 30.20 parts by mass (0.097 mol), 42.96 parts by mass (0.141 mol) of SPG, BPFM 31.01.01 parts by mass (0.048 mol), 41.98 parts by mass (0.196 mol) of DPC and 1.26X10- ^-2 parts by mass (7.15X10- ^-5 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 5

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that 30.20 parts by mass (0.097 mol), 44.69 parts by mass (0.147 mol) of SPG, BPFM 28.19.19 parts by mass (0.044 mol), 44.17 parts by mass (0.206 mol) of DPC and 1.29X10: 10 ^-2 parts by mass (7.32X10 ^-5 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 6

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that BisP-AP 30.21 parts by mass (0.104 mol), SPG 40.19 parts by mass (0.132 mol), BPFM 35.24.24 parts by mass (0.055 mol), DPC 40.06 parts by mass (0.187 mol) and 1.25X10- ^-2 parts by mass (7.08X10- ^-5 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 7

Pellets of a polyester carbonate were obtained in the same manner as in example 1 except that BisP-CDE 30.17 parts by mass (0.086 mol), SPG 43.26 parts by mass (0.142 mol), BPFM 31.01.01 parts by mass (0.048 mol), DPC 39.64 parts by mass (0.185 mol) and 1.20X10 ^-2 parts by mass (6.83X10 ^-5 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 8

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that BisP-CDE 30.17 parts by mass (0.086 mol), SPG 40.67 parts by mass (0.134 mol), BPFM 35.24.24 parts by mass (0.055 mol), DPC 36.35 parts by mass (0.170 mol) and calcium acetate monohydrate 1.16X10. 10 ^-2 parts by mass (6.58X10. 10 ^-5 mol) as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 9

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that 20.13 parts by mass (0.065 mol), 52.15 parts by mass (0.171 mol) of SPG, BPFM 20.13.13 parts by mass (0.051 mol), 41.02 parts by mass (0.191 mol) of DPC and 1.25X10. 10 ^-2 parts by mass (7.09X 10 ^-5 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 10

The same procedure as in example 1 was repeated except that 20.13 parts by mass (0.065 mol) of BP-TMC, 41.14 parts by mass (0.135 mol) of SPG, 10.14 parts by mass (0.069 mol) of ISB, BPFM 32.42.42 parts by mass (0.051 mol) of DPC 48.31 parts by mass (0.226 mol) and 1.42X10 ^-2 parts by mass (8.08X10 ^-5 mol) of calcium acetate monohydrate as a catalyst were used as the steps of the second stage of the reaction, and the temperature of the heating medium was raised to 245℃for 15 minutes to obtain polyester carbonate pellets. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 11

The same procedure as in example 1 was repeated except that 10.06 parts by mass (0.032 mol) of BP-TMC, 35.12 parts by mass (0.115 mol) of SPG, 25.35 parts by mass (0.173 mol) of ISB, BPFM 31.72 parts by mass (0.049 mol) of DPC 58.91 parts by mass (0.275 mol) and 1.70X10- ^-2 parts by mass (9.64X10-5 mol) of calcium acetate monohydrate as a catalyst were used as the steps of the second stage of the reaction, and the temperature of the heating medium was raised to 250℃for 15 minutes to obtain polyester carbonate pellets. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 12

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that 15.10 parts by mass (0.049 mol) of BP-TMC, 52.97 parts by mass (0.174 mol) of SPG, 5.07 parts by mass (0.035 mol) of ISB, 30.31 parts by mass (0.047 mol) of BPFM, 46.37 parts by mass (0.216 mol) of DPC and 1.36X10- ^-2 parts by mass (7.72X10-5 mol) of calcium acetate monohydrate as a catalyst were used as the steps of the second stage of the reaction, and the temperature of the heating medium was raised to 250℃for 15 minutes. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 13

The same procedure as in example 1 was repeated except that BisP-CDE 20.11 parts by mass (0.057 mol), SPG 41.35 parts by mass (0.136 mol), ISB 10.14 parts by mass (0.069 mol), BPFM 32.42.42 parts by mass (0.051 mol), DPC 46.75 parts by mass (0.218 mol) and calcium acetate monohydrate 1.39X10- ^-2 parts by mass (7.87X10-5 mol) as a catalyst were used as the steps of the second stage of the reaction, and the temperature of the heating medium was raised to 250℃for 15 minutes to obtain pellets of a polyester carbonate. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Example 14

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that, as the second stage of the reaction, 10.06 parts by mass (0.029 mol) of BisP-CDE, 36.52 parts by mass (0.120 mol) of SPG, 25.35 parts by mass (0.173 mol) of ISB, 29.60 parts by mass (0.046 mol) of BPFM, 59.76 parts by mass (0.279 mol) of DPC and 1.70X10- ^-2 parts by mass (9.66X10-5 mol) of calcium acetate monohydrate as a catalyst were used, and the temperature of the heating medium was raised to 250℃for 15 minutes. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 3.

Comparative example 1

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that 25.16 parts by mass (0.082 mol) of SBI, 56.62 parts by mass (0.186 mol) of SPG, BPFM 16.92.92 parts by mass (0.026 mol) of DPC 52.82 parts by mass (0.247 mol) and 1.41X10- ^-2 parts by mass (8.03X10- ^-5 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 2 and 4.

Comparative example 2

Pellets of polycarbonate were obtained in the same manner as in example 1, except that 20.13 parts by mass (0.065 mol) of SBI, 48.91 parts by mass (0.161 mol) of SPG, 10.14 parts by mass (0.069 mol) of ISB, BPFM 19.74.74 parts by mass (0.031 mol) of DPC, 58.25 parts by mass (0.272 mol) of calcium acetate monohydrate 1.56X10. 10 ^-2 parts by mass (8.86X 10 ^-5 mol) as a catalyst were used as the steps of the second stage of the reaction, and the temperature of the heating medium was raised to 250℃for 15 minutes. The above-described various evaluations were performed using the obtained polycarbonate pellets. The results are shown in tables 1 to 2 and 4.

Comparative example 3

Pellets of a polyester carbonate were obtained in the same manner as in example 10, except that 30.20 parts by mass (0.099 mol) of SPG, 39.94 parts by mass (0.273 mol) of ISB, BPFM 30.31.31 parts by mass (0.047 mol) of DPC 69.67 parts by mass (0.325 mol) and 9.84X10- ^-4 parts by mass (5.59X10- ^-6 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 2 and 4.

Comparative example 4

Polycarbonate pellets were obtained in the same manner as in comparative example 3, except that 26.72 parts by mass (0.183 mol) of ISB, 1000#0.99 parts by mass (0.001 mol) of PEG, 63.74 parts by mass (0.145 mol) of BHEPF, 70.24 parts by mass (0.328 mol) of DPC and 8.69×10 ^-4 parts by mass (4.93×10 ^-6 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polycarbonate pellets. The results are shown in tables 1 to 2 and 4.

Comparative example 5

The same procedure as in example 1 was repeated except that 10.07 parts by mass (0.032 mol), 54.13 parts by mass (0.370 mol) of ISB, BPFM 38.06.06 parts by mass (0.059 mol), 74.43 parts by mass (0.347 mol) of DPC and 1.06X10-3 parts by mass (6.04X 10 ^-6 mol) of calcium acetate monohydrate as a catalyst were used as steps in the second stage of the reaction, and the temperature of the heating medium was raised to 250℃for 15 minutes to obtain polycarbonate pellets. The above-described various evaluations were performed using the obtained polycarbonate pellets. The results are shown in tables 1 to 2 and 4.

Comparative example 6

The same procedure as in example 1 was repeated except that 24.16 parts by mass (0.078 mol) of BP-TMC, 28.45 parts by mass (0.195 mol) of ISB, BPFM 30.45.45 parts by mass (0.048 mol) of DPC 49.70 parts by mass (0.232 mol) and 1.44X10-3 parts by mass (8.18X10- ^-6 mol) of calcium acetate monohydrate as a catalyst were used as steps in the second stage of the reaction, and the temperature of the heating medium was raised to 250℃for 15 minutes to obtain polycarbonate pellets. The polycarbonate obtained in this comparative example was brittle and could not be used for evaluation because a film molded article could not be produced.

Comparative example 7

Pellets of a polyester carbonate were obtained in the same manner as in example 1, except that 38.18 parts by mass (0.101 mol) of BCF, 54.56 parts by mass (0.179 mol) of SPG, 62.40 parts by mass (0.291 mol) of DPC and 2.47X10-2 parts by mass (1.40X10 ^-4 mol) of calcium acetate monohydrate as a catalyst were used. The above-described various evaluations were performed using the obtained polyester carbonate particles. The results are shown in tables 1 to 2 and 4.

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TABLE 4

TABLE 4 Table 4

As is clear from tables 1 to 3, the polycarbonate resins of examples 1 to 14 containing the structural unit (A), the structural unit (B) and the structural unit (C) are excellent in wet heat resistance and optical characteristics. On the other hand, as is clear from tables 1, 2 and 4, the polycarbonate resins of comparative examples 1 to 3 containing no structural unit (B) have low wet heat resistance and toughness. The polycarbonate resin of comparative example 4, which does not contain the structural unit (a), the structural unit (B) and the structural unit (C), has poor optical characteristics. Comparative example 5 containing no structural unit (C) was unsuitable for use as a retardation film under high humidity and heat because of high water absorption and large dimensional change rate, and was poor in melt processability because of high glass transition temperature. In addition, comparative example 6 containing no structural unit (C) could not be molded into a film shape, and the molding was poor. In addition, comparative example 7 containing no structural unit (a) was low in toughness.

Claims

1. A polycarbonate resin, comprising:

a structural unit A represented by the following formula (1) and/or the following formula (2),

A structural unit B represented by the following formula (3), and

Structural unit C derived from a dihydroxy compound having an acetal ring structure,

[ Chemical 1]

Wherein, in the above formula (1), R ¹～R³ each independently represents a direct bond, or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, R ⁴～R⁹ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted acyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 2 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 2 to 10 carbon atoms, a sulfur atom having a substituent, a halogen atom, a nitro group or a cyano group, R ⁴～R⁹ are the same or different from each other, and at least two adjacent groups in R ⁴～R⁹ are bonded to each other to form a ring or are not bonded to each other;

[ chemical 2]

Wherein, in the above formula (2), each R ¹～R³ independently represents a direct bond, or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, each R ⁴～R⁹ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a substituted or unsubstituted acyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 2 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 2 to 10 carbon atoms, a sulfur atom having a substituent, a halogen atom, a nitro group or a cyano group, and R ⁴～R⁹ are the same or different from each other, and at least two adjacent groups in R ⁴～R⁹ are bonded to each other to form a ring or are not bonded to each other;

[ chemical 3]

Wherein in the above formula (3), R ¹⁰～R¹⁷ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, and X ¹ represents a direct bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.

2. The polycarbonate resin according to claim 1, wherein R ¹⁰～R¹⁷ in the above formula (3) is each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, and X ¹ is a substituted or unsubstituted chain alkylene group having 1 to 20 carbon atoms, a substituted or unsubstituted cyclic alkylene group having 6 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a fluorenylene group having 13 to 20 carbon atoms.

3. The polycarbonate resin according to claim 1 or 2, wherein the content of the structural unit a is 1 mass% or more and 45 mass% or less relative to 100 mass% of the total of the content of all the structural units and the linking groups constituting the polycarbonate resin.

4. The polycarbonate resin according to any one of claims 1 to 3, wherein the content of the structural unit B is 5 mass% or more and 50 mass% or less relative to 100 mass% of the total of the content of all the structural units and the linking groups constituting the polycarbonate resin.

5. The polycarbonate resin according to any one of claims 1 to 4, wherein the content of the structural unit C is 15 mass% or more and 75 mass% or less relative to 100 mass% of the total of the content of all the structural units and the linking groups constituting the polycarbonate resin.

6. The polycarbonate resin according to any one of claims 1 to 5, further comprising: a structural unit D derived from at least one compound selected from the group consisting of aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, oxyalkylene glycols and dihydroxy compounds having a heterocyclic structure.

7. The polycarbonate resin according to claim 6, wherein the total content of the structural units C and the structural units D is 20 mass% or more and 80 mass% or less relative to 100 mass% of the total content of all the structural units and the linking groups constituting the polycarbonate resin.

8. The polycarbonate resin according to claim 6 or 7, wherein the structural unit C is a structural unit represented by the following formula (4), and the structural unit D is a structural unit represented by the following formula (5):

[ chemical 4]

[ Chemical 5]

9. The polycarbonate resin according to any one of claims 1 to 8, wherein the glass transition temperature of the polycarbonate resin is 120 ℃ or more and 160 ℃ or less.

10. The polycarbonate resin according to any one of claims 1 to 9, wherein the water absorption rate of the polycarbonate resin is 1.4% or less.

11. A polycarbonate resin molded article comprising the polycarbonate resin according to any one of claims 1 to 10.

12. A film composed of the polycarbonate resin of any one of claims 1 to 10.

13. A retardation film comprising the film of claim 12.

14. The retardation film as claimed in claim 13, wherein the ratio of the retardation R450 at a wavelength of 450nm to the retardation R550 at a wavelength of 550nm, i.e., the value of wavelength dispersion, is 0.60 or more and 1.00 or less.

15. A circularly polarizing plate comprising the phase difference film of claim 13 or 14.

16. An image display device comprising the circularly polarizing plate of claim 15.

17. A method for producing a transparent film, wherein in the method for producing a transparent film by molding the polycarbonate resin according to any one of claims 1 to 10 by a melt film-forming method,

And molding the polycarbonate resin at a molding temperature of 280 ℃ or lower.

18. A polycarbonate resin, comprising:

a structural unit A represented by the following formula (1) and/or the following formula (2), and

A structural unit B represented by the following formula (3),

The water absorption rate of the polycarbonate resin is less than 1.4 percent,

[ Chemical 6]

[ chemical 7]

[ chemical 8]