JP2018197848A - Polarizing plate protective film, manufacturing method therefor, and polarizing plate - Google Patents

Abstract

To provide a polarizing plate protective film exhibiting low birefringence or a phase difference (in-plane retardation R0 and thickness direction retardation Rth), capable of suppressing rainbow unevenness and light leakage even when being formed of a polymer alloy containing a polycarbonate resin which tends to raise birefringence, and a manufacturing method therefor, and a polarizing plate including the polarizing film.SOLUTION: A disclosed polarizing plate protective film in which at least one structural unit in a diol unit (A) and a dicarboxylic acid unit (B) contains a polymer alloy containing a fluorene polyester resin containing at least one unit having a fluorene skeleton selected from a fluorene-9,9-diyl skeleton and a fluoren-9-yl skeleton and an aromatic polycarbonate resin.SELECTED DRAWING: None

Description

  The present invention relates to a polarizing plate protective film (or a polarizer protective film) comprising a polymer alloy containing a fluorene polyester resin having a fluorene-9,9-diyl skeleton or a fluoren-9-yl skeleton and an aromatic polycarbonate resin, and the same. The present invention relates to a manufacturing method, a polarizing plate including the polarizing plate protective film, and an image display device including the polarizing plate.

  As a polarizer (or a polarizing functional layer) of a polarizing plate used for an image display device, conventionally, a polyvinyl alcohol (PVA) resin film is dyed with iodine or a dichroic dye and oriented by stretching or the like. It is used. Since this polarizer is easily affected by ultraviolet rays, moisture, heat, etc., there is a possibility that the polarization performance may deteriorate due to decomposition or dimensional change. Therefore, a polarizer is usually used as a polarizing plate in which a transparent polarizing plate protective film (or a polarizing plate protective film) is bonded to one or both surfaces with an adhesive or the like. The polarizer protective film is required to have optical properties such as being transparent and optically isotropic (low retardation or birefringence), and further excellent in adhesion to PVA. Acetyl cellulose (TAC) film is commonly used.

  In the field of image display devices, in recent years, with the price reduction of liquid crystal televisions and the like, cost reduction has been promoted by transporting liquid crystal panels in simple packaging. Therefore, the polarizing plate also needs durability against a temperature difference and a humidity difference during transportation, and in particular, the need for a polarizing plate with low moisture permeability is increasing. On the other hand, in parallel with cost reduction, liquid crystal displays are also required to be thin, and accordingly, polarizing plates are also required to be thin. In order to meet these demands, the TAC film, which is a typical polarizing plate protective film, has been studied to reduce moisture permeability and thickness, but there is a limit to reducing the moisture permeability of TAC films that originally have high moisture permeability. There is. Furthermore, since the moisture becomes easier to permeate by making the film thinner, not only lowering the moisture permeability becomes even more difficult, but also the mechanical strength is greatly reduced, so the development of a polarizing plate protective film that replaces the TAC film is proceeding. It has been.

  For example, International Publication No. 2006/112207 (Patent Document 1) and International Publication No. 2005/054311 (Patent Document 2) disclose modified acrylic resin films having a ring structure such as a lactone ring or an imide ring. .

  However, in the modified acrylic resin film, in the process in which heat is applied to the modified acrylic resin, gelled products that cause image defects (or image quality degradation) are likely to occur, and the productivity may decrease. In addition, although the moisture permeability is as low as about 1/10 of that of a TAC film, the film itself is hard and brittle, so that it is easy to crack from the edge when handling cutting, laminating, winding, etc. There is also a risk of decline. Since such a tendency becomes conspicuous as the film becomes thinner, the present situation cannot sufficiently meet the demand for the thinner film.

  Further, in Japanese Patent No. 4926661 (Patent Document 3), even if it is an oriented polyester film which has a large retardation value and rainbow unevenness and cannot usually be used as a polarizing plate protective film, it is 3000 nm contrary to the conventional case. It is disclosed that by controlling to the above high retardation value and combining with a specific backlight light source, rainbow unevenness can be eliminated and it can be used as a polarizing plate protective film. In the examples of this document, a laminated film laminated in three layers is produced using a polyethylene terephthalate resin (PET) which has a moisture permeability lower than that of a modified acrylic resin and excellent in mechanical strength.

  However, since the film of this document requires a retardation value several times to 10 times that of general-purpose PET, it is difficult to reduce the film thickness proportional to the retardation value, which is sufficient for the demand for thinning. Cannot handle. In addition, since the film has a multilayer structure, productivity is difficult to improve, and the type of backlight light source is limited.

  In addition to the modified acrylic resin and PET, a polycarbonate resin is known as an optical material having excellent properties such as transparency, heat resistance, mechanical properties (toughness), dimensional stability, and low moisture permeability. However, the polycarbonate resin has low moldability, and for example, when stretched at a high magnification, the film may be broken, so that it is difficult to reduce the film thickness. Also, the polycarbonate resin is a protective film for polarizing plate because the birefringence (or retardation) that causes rainbow unevenness and light leakage is likely to increase due to the influence of molecular orientation generated during the molding process such as stretching without breaking. Not available as On the other hand, Japanese Patent Application Laid-Open No. 2011-8017 (Patent Document 4) reduces birefringence by using a resin composition in which a fluorene compound having a 9,9-bisarylfluorene skeleton is added at a specific ratio. Further, it is disclosed that the amount of fluorene compound added is small and bleeding out can be suppressed.

  However, in this resin composition, although bleed out of the fluorene compound can be suppressed to some extent, the fluorene compound is a low-molecular compound, and its suppression effect is not yet sufficient. In addition to not being able to stably maintain optical characteristics such as phase difference), when a polarizing plate is formed, the characteristics of other adjacent layers (polarization functional layer, adhesive layer, etc.) may be degraded. The durability of the plate is reduced. Further, this document does not describe any characteristics such as rainbow unevenness when used as a thickness direction retardation Rth or a polarizing plate protective film.

  JP 2008-133447 A (Patent Document 5) discloses a transparent alloy in which a polyester resin containing a diol having a 9,9-bisarylfluorene skeleton as a polymerization component and a polycarbonate resin are completely compatible. It is described that it is often formed, and furthermore, since birefringence can be freely controlled by the type and addition amount of polycarbonate resin, it can be used as an optical film raw material.

  However, in the examples, no specific polymer alloy has been prepared. Further, although this document exemplifies a polarizing plate protective film in parallel with various optical films, in the examples, the film formed with the polyester resin alone is retardation when uniaxially stretched until it breaks. The value Re (in-plane phase difference) is only evaluated.

International Publication No. 2006/112207 International Publication No. 2005/054311 Japanese Patent No. 4926661 JP 2011-8017 A JP 2008-133447 A

  Accordingly, an object of the present invention is to exhibit a low birefringence or retardation (in-plane retardation R0 and thickness direction retardation Rth) even when formed of a polymer alloy containing a polycarbonate resin whose birefringence tends to increase. An object of the present invention is to provide a polarizing plate protective film in which unevenness and light leakage are suppressed, a method for producing the same, and a polarizing plate including the polarizing plate protective film.

  Another object of the present invention is to provide a polarizing plate protective film that can be easily melted and formed into a thin film even if it contains a polycarbonate resin having a low moldability or a polyester resin having a rigid fluorene skeleton, and a method for producing the same, And it is providing the polarizing plate containing the said polarizing plate protective film.

  Still another object of the present invention is to provide a polarizing plate protective film having a low moisture permeability and high mechanical strength, a manufacturing method thereof, and a polarizing plate including the polarizing plate protective film, even if it is a thin film. .

  Another object of the present invention is to provide a polarizing plate protective film excellent in durability, a method for producing the same, and a polarizing plate including the polarizing plate protective film.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have increased the birefringence when a polarizing plate protective film is formed from a polymer alloy containing a polyester resin having a specific fluorene skeleton and an aromatic polycarbonate resin. Despite the inclusion of easy polycarbonate resin, unexpectedly low birefringence or retardation (in-plane retardation R0 and thickness direction retardation Rth) was found, and it was found that rainbow unevenness and light leakage could be suppressed, and the present invention was completed. did.

  That is, in the polarizing plate protective film of the present invention, at least one of the diol units (A) and the dicarboxylic acid units (B) is selected from a fluorene-9,9-diyl skeleton and a fluoren-9-yl skeleton. A polymer alloy containing a fluorene polyester resin containing a unit having at least one fluorene skeleton and an aromatic polycarbonate resin.

  The fluorene polyester resin may contain at least one structural unit selected from the first diol unit (A1) and the first dicarboxylic acid unit (B1). The first diol unit (A1) is a structural unit represented by the following formula (A1), and the first dicarboxylic acid unit (B1) is represented by the following formula (B1-1) or (B1-2). Is a structural unit.

Wherein Z ¹ is independently an arene ring, R ¹ and R ² are each independently a substituent, A ¹ is each independently a linear or branched alkylene group, and k is each independently An integer of 0 to 4, m is each independently an integer of 0 or more, and n is each independently an integer of 1 or more).

(In the formula, R ³ is each independently a substituent, p and q are each independently an integer of 0 to 4, and A ² and A ³ are each independently a divalent which may have a substituent. Represents a hydrocarbon group).

In the formula (A1), Z ¹ is a C _6-10 arene ring, R ² is a C _1-4 alkyl group or a C _6-10 aryl group, and A ¹ is a linear or branched C _2-4 alkylene group. , k is an integer of 0 to 2, m is an integer of 0 to 2, n may be an integer of 1 to 10, in the formula (B1-1), p is an integer of 0 to 2, ^{a 2} is straight It may be a chain or branched C _2-4 alkylene group. The ratio of the total amount of the first diol unit (A1) and the first dicarboxylic acid unit (B1) may be 10 to 100 mol% with respect to the entire constituent units of the fluorene polyester resin.

  The fluorene polyester resin may contain a second diol unit (A2) represented by the following formula (A2).

(In the formula, A ⁴ represents a linear or branched alkylene group, and r represents an integer of 1 or more).

In the formula (A2), A ⁴ may be a linear or branched C _2-4 alkylene group, r may be an integer of 1 to 3, and the first diol unit (A1) and the second diol The ratio with the unit (A2) may be the former / the latter (molar ratio) = 97/3 to 50/50.

  The fluorene polyester resin may contain a second dicarboxylic acid unit (B2) represented by the following formula (B2).

(Wherein Z ² is an aliphatic ring or arene ring, R ⁴ is a substituent, and s is an integer of 0 or more).

In the formula (B2), Z ² is a C _5-10 cycloalkane ring or C _6-10 arene ring, R ⁴ is a C _1-4 alkyl group or a C _6-10 aryl group, and s is an integer of 0-4. There may be. The ratio of the second dicarboxylic acid unit (B2) may be 10 to 100 mol% with respect to the entire dicarboxylic acid unit (B).

  The aromatic polycarbonate resin may be a bisphenol type polycarbonate resin. The ratio of the fluorene polyester resin and the aromatic polycarbonate resin may be the former / the latter (weight ratio) = 50/50 to 1/99.

  The thickness of the polarizing plate protective film of the present invention may be 10 to 50 μm. The in-plane retardation R0 at a wavelength of 550 nm and a thickness of 25 μm may be 0 to 100 nm, and the thickness direction retardation Rth at a wavelength of 589 nm and a thickness of 25 μm may be 0 to 300 nm.

  The present invention includes a polarizing plate including a polarizing functional layer and the polarizing plate protective film.

  The present invention also relates to a fluorene polyester resin in which at least one of the diol units (A) and dicarboxylic acid units (B) includes a unit having a fluorene-9,9-diyl skeleton or a fluoren-9-yl skeleton. And the manufacturing method of the said polarizing plate protective film including the process of extruding the polymer alloy which has aromatic polycarbonate resin is included. A step of subjecting the film obtained by extrusion to uniaxial or biaxial stretching may be further included.

  In the present specification and claims, the “polymer alloy” is a mixture (or mixture) in which a plurality of macromolecules (or polymers and resins) are mixed without being connected by a covalent bond, It means that the resin component is in a completely compatible state or in a stable microphase separation state.

  In the present specification and claims, “dicarboxylic acid unit” or “structural unit derived from a dicarboxylic acid component” is a unit obtained by removing OH (hydroxyl group) from two carboxyl groups of the corresponding dicarboxylic acid ( Or a “dicarboxylic acid component” (including compounds exemplified as the dicarboxylic acid component) may be used synonymously with the corresponding “dicarboxylic acid unit”. Similarly, the “diol unit” or “structural unit derived from the diol component” means a unit (or a divalent group) obtained by removing a hydrogen atom from two hydroxyl groups of the corresponding diol component, “Component” (including compounds exemplified as the diol component) may be used synonymously with the corresponding “diol unit”.

In the present specification and claims, the “dicarboxylic acid component” means, in addition to dicarboxylic acid, an ester-forming derivative thereof [for example, dicarboxylic acid lower alkyl ester (methyl ester, ethyl ester, t-butyl ester, etc. C _1-4 alkyl ester, etc.), dicarboxylic acid halide, dicarboxylic acid anhydride, etc.]. The “ester-forming derivative” may be a monoester (half ester) or a diester.

In the present specification and claims, the number of carbon atoms of the substituent may be indicated by C ₁ , C ₆ , C ₁₀ or the like. That is, for example, an alkyl group having 1 carbon atom is represented by “C ₁ alkyl”, and an aryl group having 6 to 10 carbon atoms is represented by “C _6-10 aryl”.

  Since the polarizing plate protective film of the present invention contains a polymer alloy containing a specific polyester resin and an aromatic polycarbonate resin, it has a low birefringence or level despite containing a polycarbonate resin that tends to increase birefringence. A phase difference (in-plane phase difference R0 and thickness direction phase difference Rth) is shown, and rainbow unevenness and light leakage can be suppressed. Despite being formed of a polymer alloy containing a polycarbonate resin known for its low moldability and a polyester resin having a rigid fluorene skeleton that is expected to have a low moldability, it is surprisingly It has high moldability, can be easily melt-formed, and can be thinned. Furthermore, even if the polarizing plate protective film of the present invention is a thin film, it exhibits low moisture permeability and high mechanical strength. Therefore, various properties required for a polarizing plate protective film, for example, high transparency (high light transmission or low reflectance), low birefringence (or retardation), low moisture permeability, high mechanical strength, thin film thickness ( (Or high moldability) and the like can be satisfied in a balanced manner. Moreover, since the polarizing plate protective film of the present invention can achieve low birefringence without using a low molecular compound, it can effectively prevent deterioration of film properties due to bleed out of the low molecular compound, and has high durability. Can be formed.

  The polarizing plate protective film (or polarizer protective film) of the present invention contains a polymer alloy containing a fluorene polyester resin and an aromatic polycarbonate resin.

[Fluorene polyester resin]
In the fluorene polyester resin, at least one of the diol units (A) and dicarboxylic acid units (B) forming the polyester resin is selected from a fluorene-9,9-diyl skeleton and a fluoren-9-yl skeleton. A unit having at least one fluorene skeleton (sometimes simply referred to as a fluorene unit).

  Of the fluorene units, usually, at least a unit having a fluorene-9,9-diyl skeleton is often included. Examples of the fluorene-9,9-diyl skeleton include a 9,9-bisarylfluorene skeleton and a 9,9-bisalkylfluorene skeleton. The fluorene unit may be contained in any constituent unit of the diol unit and the dicarboxylic acid unit, but the diol unit having a 9,9-bisarylfluorene skeleton and the dicarboxylic acid unit having a 9,9-bisalkylfluorene skeleton In many cases. Therefore, the fluorene polyester resin often contains at least one structural unit selected from the first diol unit (A1) and the first dicarboxylic acid unit (B1) described below. In many cases, it contains a diol unit (A1).

(Diol unit (A))
First diol unit (A1)
The diol unit (A) may include a first diol unit (A1) represented by the following formula (A1).

Wherein Z ¹ is independently an arene ring, R ¹ and R ² are each independently a substituent, A ¹ is each independently a linear or branched alkylene group, and k is each independently An integer of 0 to 4, m is each independently an integer of 0 or more, and n is each independently an integer of 1 or more).

In the formula (A1), examples of the arene ring (aromatic hydrocarbon ring) represented by Z ¹ include a monocyclic arene ring such as a benzene ring, a polycyclic arene ring, and the like. The arene ring includes a condensed polycyclic arene ring (condensed polycyclic aromatic hydrocarbon ring), a ring assembly arene ring (ring assembly aromatic hydrocarbon ring) and the like.

Examples of the condensed polycyclic arene ring include a condensed bicyclic arene ring (for example, a condensed bicyclic C _10-16 arene ring such as a naphthalene ring and an indene ring), and a condensed tricyclic arene ring (for example, an anthracene ring). And condensed bi- to tetra-cyclic arene rings and the like. Preferred ring-fused polycyclic arene rings include fused polycyclic C _10-16 arene rings such as naphthalene rings and anthracene rings, preferably fused polycyclic C _10-14 arene rings. preferable.

Examples of the ring assembly arene ring include a bearene ring (for example, a bi-C _6-12 arene ring such as a biphenyl ring, a binaphthyl ring, a phenylnaphthalene ring (a 1-phenylnaphthalene ring, a 2-phenylnaphthalene ring, etc.), a tellarene ring ( For example, a tel C _6-12 arene ring such as a terphenylene ring) can be exemplified. A preferable ring assembly arene ring includes a bi-C _6-10 arene ring, and a biphenyl ring is particularly preferable.

The types of the two rings Z ¹ may be the same or different from each other and are usually the same. Among the ring Z ¹ , C _6-12 arene rings such as benzene ring, naphthalene ring, biphenyl ring and the like are preferable, and among them, C _6-10 arene rings such as benzene ring and naphthalene ring are preferable. A benzene ring is preferable because it can be easily reduced.

Incidentally, the substitution position of the ring Z ¹ which binds to the 9-position of the fluorene ring is not particularly limited. For example, when ring Z ¹ is a benzene ring, it may be in any position of 1 to 6 position, and when ring Z ¹ is a naphthalene ring, it may be in either position 1 or 2 position. In the case where ring Z ¹ is a biphenyl ring, it may be in any of the 2-position, 3-position, and 4-position.

Examples of the substituent represented by R ¹ include a hydrocarbon group [for example, an alkyl group (for example, a linear or branched group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a t-butyl group, etc. Chain C _1-6 alkyl group etc.), aryl group (eg C _6-10 aryl group such as phenyl group etc.)], cyano group, halogen atom (eg fluorine atom, chlorine atom, bromine atom etc.) etc. Is mentioned. Among these groups R ¹ , when the number of substitution k is 1 or more, an alkyl group, a cyano group, and a halogen atom are preferable, and among them, an alkyl group, particularly a linear or branched C _1-1 such as a methyl group. _{A 4-} alkyl group is preferred, and no substituent (k = 0) is most preferred.

The substitution number k of the group R ¹ is, for example, an integer of about 0 to 3, preferably an integer of 0 to 2, more preferably 0 or 1, especially 0. In addition, in two different benzene rings constituting the fluorene ring, the respective substitution numbers k may be the same or different from each other. In addition, the types of the groups R ¹ substituted on two different benzene rings may be different from each other and are usually the same. When k is 2 or more, the types of two or more groups R ¹ substituted on the same benzene ring may be the same or different from each other. The substitution position of the group R ¹ is not particularly limited, and may be, for example, the 2nd to 7th positions (the 2nd position, the 3rd position, the 7th position, etc.) of the fluorene ring.

Examples of the substituent represented by R ² include a halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom); hydrocarbon group {eg, alkyl group (methyl group, ethyl group, propyl group, isopropyl group) Group, n-butyl group, isobutyl group, s-butyl group, t-butyl group and the like linear or branched C _1-10 alkyl group, preferably linear or branched C _1-6 alkyl group More preferably a linear or branched C _1-4 alkyl group); a cycloalkyl group (eg, a C _5-10 cycloalkyl group such as a cyclopentyl group, a cyclohexyl group, etc.); an aryl group [eg, a phenyl group , alkylphenyl group (e.g., methylphenyl group (tolyl group), such as a dimethylphenyl group (xylyl)), biphenylyl groups, C such as naphthyl _{6- 2} an aryl group]; aralkyl groups (e.g., benzyl group, etc. _{C 6-10} aryl _{-C 1-4} alkyl group such as a phenethyl group), etc.}; alkoxy group (e.g., methoxy group, an ethoxy group, a propoxy radical, n A linear or branched C _1-10 alkoxy group such as a butoxy group, an isobutoxy group, an s-butoxy group or a t-butoxy group; a cycloalkyloxy group (for example, a C _5-10 such as a cyclohexyloxy group) Cycloalkyloxy group etc.); aryloxy group (eg C _6-10 aryloxy group such as phenoxy group); aralkyloxy group (eg C _6-10 aryl-C _1-4 alkyloxy such as benzyloxy group) Group); alkylthio group (for example, methylthio group, ethylthio group, propylthio group, n-butylthio group) Groups, such as _{C 1-10} alkylthio group such as t- butylthio group); cycloalkylthio group (e.g., a _{C 5-10} cycloalkylthio groups such as cyclohexyl thio group); _{C 6,} such as an arylthio group (e.g., a thiophenoxy group _-10 arylthio group, etc.); aralkylthio group (eg, C _6-10 aryl-C _1-4 alkylthio group such as benzylthio group); acyl group (eg, C _1-6 acyl group such as acetyl group); Nitro group; cyano group; substituted amino group [for example, dialkylamino group (for example, _diC1-4 alkylamino group such as dimethylamino group); bis (alkylcarbonyl) amino group (for example, bis such as diacetylamino group) (C _1-4 alkyl-carbonyl) amino group, etc.)] and the like.

Of these groups R ² , typically, a halogen atom, a hydrocarbon group (alkyl group, cycloalkyl group, aryl group, aralkyl group), alkoxy group, acyl group, nitro group, cyano group, substituted amino group, etc. Is mentioned. Preferred groups R ² include an alkyl group, an aryl group, and an alkoxy group. Examples of the alkyl group include a linear or branched C _1-6 alkyl group such as a methyl group. As an aryl group, And a C _6-12 aryl group such as a phenyl group, and the alkoxy group includes a linear or branched C _1-4 alkoxy group such as a methoxy group. Among these, an alkyl group and an aryl group are preferable, and a C _6-10 aryl group such as a linear or branched C _1-4 alkyl group such as a methyl group or a phenyl group is particularly preferable.

The substitution number m of the group R ² can be appropriately selected according to the type of the ring Z ¹ , and may be an integer of about 0 to 8, for example, and preferably in the following stepwise, an integer of 0 to 4, An integer of 3, an integer of 0 to 2, 0 or 1, especially 0. In two different rings Z ¹ , the type of the group R ² and the number of substitutions m may be the same or different from each other. When the number m of substitutions is 2 or more, the types of the two or more groups R ² substituted on the same ring Z ¹ may be the same or different from each other. The substitution position of the group R ² is not particularly limited as long as it is substituted at a position other than the bonding position between the ring Z ¹ and the 9-position of the group [—O— (A ¹ O) _n —] and the fluorene ring. Good.

The linear or branched alkylene group represented by A ^1, for example, ethylene group, propylene group (1,2-propanediyl), trimethylene, 1,2-butanediyl group, a tetramethylene group A linear or branched C _2-6 alkylene group, and the like, preferably a linear or branched C _2-4 alkylene group, more preferably a linear or branched C _2-3 alkylene group. In particular, it is an ethylene group.

The repeating number (added mole number) n of the oxyalkylene group (OA ¹ ) may be an integer of 1 or more, and can be selected from, for example, about 1 to 15, for example, an integer of 1 to 10, preferably 1 An integer of ˜8, more preferably an integer of 1 to 6, more preferably an integer of 1 to 4, especially an integer of 1 to 2, and preferably 1 from the viewpoint of polymerization reactivity. In the present specification and claims, the “repetition number (number of added moles) n” may be an average value (arithmetic average value, arithmetic average value) or an average number of added moles. , May be the same as the preferred integer range. If the repetition number n is too large, it may be difficult to reduce birefringence (or phase difference) and moisture permeability, and heat resistance may also be reduced. The two repeating numbers n may be the same or different, and when n is 2 or more, the types of the two or more oxyalkylene groups (OA ¹ ) may be different from each other, and are usually the same. There are many cases. Moreover, the kind of the oxyalkylene group (OA ¹ ) bonded to two different rings Z ¹ via an ether bond (—O—) may be the same or different from each other.

The substitution position of the group [—O— (A ¹ O) _n —] is not particularly limited as long as it is a position other than the bonding position between the ring Z ¹ and the fluorene ring. For example, the ring Z ¹ is a benzene ring. In this case, the position may be any one of positions 2 to 6 of the phenyl group bonded to position 9 of the fluorene ring. When ring Z ¹ is a naphthalene ring, it is usually substituted at any of positions 5 to 8 of the naphthyl group bonded at position 1 or 2 with respect to position 9 of the fluorene ring, The 9th position of the fluorene ring is substituted at the 1st or 2nd position of the naphthalene ring (substituted by the relationship of 1-naphthyl or 2-naphthyl). Substituents, etc., in particular, are preferably substituted in a 2-6 position relationship. When ring Z ¹ is a biphenyl ring, it may be substituted at any of positions 2-6 and 2′-6 ′ of the biphenyl ring. For example, fluorene is located at the 3-position or 4-position of the biphenyl ring. In the case where the 3-position of the biphenyl ring is bonded to the 9-position of fluorene, the substitution position of the carbonyl group is, for example, the 2-position, 4-position, 5-position, 6-position of the biphenyl ring, The position may be any of the 2′-position, the 3′-position and the 4′-position, preferably the 6-position or the 4′-position, and particularly preferably substituted at the 6-position. When the 4-position of the biphenyl ring is bonded to the 9-position of fluorene, the substitution position of the carbonyl group is any of the 2-position, 3-position, 2′-position, 3′-position and 4′-position of the biphenyl ring. It may be any one of the 2-position and the 4′-position, and particularly preferably substituted at the 2-position.

  The first diol unit (A1) is a structural unit derived from (or corresponding to) the first diol component (A1). As a representative first diol component (A1), for example, the above formula (A1) ), 9,9-bis [hydroxy (poly) alkoxyaryl] fluorenes corresponding to units in which n is 1 or more, for example, 1 to 10, preferably 1 to 6, more preferably 1 to 3, and the like. It is done. In the present specification and claims, unless otherwise specified, “(poly) alkoxy” is used to mean including both an alkoxy group and a polyalkoxy group.

  Examples of 9,9-bis [hydroxy (poly) alkoxyaryl] fluorenes include (A1-1) 9,9-bis [hydroxy (poly) alkoxyphenyl] fluorene, (A1-2) 9,9-bis. [Hydroxy (poly) alkoxy-alkylphenyl] fluorene, (A1-3) 9,9-bis [hydroxy (poly) alkoxy-arylphenyl] fluorene, (A1-4) 9,9-bis [hydroxy (poly) alkoxy Naphthyl] fluorene and the like.

Examples of the (A1-1) 9,9-bis [hydroxy (poly) alkoxyphenyl] fluorene include 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [4 9,9-bis [hydroxy (mono-deca) C _2-, such as-(2-hydroxypropoxy) phenyl] fluorene, 9,9-bis [4- (2- (2-hydroxyethoxy) ethoxy) phenyl] fluorene _4- alkoxy-phenyl] fluorene and the like.

Examples of the (A1-2) 9,9-bis [hydroxy (poly) alkoxy-alkylphenyl] fluorene include 9,9-bis [4- (2-hydroxyethoxy) -3-methylphenyl] fluorene, 9 9,9-bis [hydroxy (mono to deca) C _2-4alkoxy- (mono or di) C _1-, such as 1,9-bis [4- (2-hydroxyethoxy) -3,5-dimethylphenyl] fluorene. _4- alkyl-phenyl] fluorene and the like.

Examples of the (A1-3) 9,9-bis [hydroxy (poly) alkoxy-arylphenyl] fluorene include 9,9-bis (4- (2-hydroxyethoxy) -3-phenylphenyl) fluorene. And 9,9-bis [hydroxy (mono to deca) C _2-4alkoxy- C _6-10aryl- phenyl] fluorene.

Examples of the (A1-4) 9,9-bis [hydroxy (poly) alkoxynaphthyl] fluorene include 9,9-bis [6- (2-hydroxyethoxy) -2-naphthyl] fluorene, 9,9- bis [5- (2-hydroxyethoxy) -1-naphthyl] fluorene such as 9,9-bis [hydroxy (mono- to _{deca) C 2-4} alkoxy - naphthyl] fluorene and the like.

These 1st diol units (A1) can also be used individually or in combination of 2 or more types. Of these the first diol units (A1), 9,9-bis [hydroxy (mono- to _{deca) C 2-4} alkoxy _{C 6-10} aryl] fluorene such as 9,9-bis [hydroxy (poly) alkoxy Preferred are structural units derived from aryl] fluorenes; among them, (A1-1) 9,9-bis [hydroxy (poly) alkoxyphenyl] fluorene, more preferably 9,9-bis [4- (2-hydroxy). ethoxy) phenyl] fluorene such as 9,9-bis [hydroxy (mono- to _{hexa) C 2-4} alkoxyphenyl] fluorene, in particular, from the viewpoint easily reduced birefringence (or retardation), 9,9-bis [ 4- from (2-hydroxyethoxy) phenyl] fluorene such as 9,9-bis [hydroxy _{C 2-4} alkoxyphenyl] fluorene That units are preferred.

  The diol unit (A) may not contain the first diol unit (A1), but the inclusion of the first diol unit (A1) makes it easy to form an alloy with the aromatic polycarbonate resin. In addition, since it can reduce birefringence (or phase difference), it is preferably included at least. The ratio of a 1st diol unit (A1) is 0-100 mol% with respect to the whole diol unit (A), For example, you may select from the range of about 1-99 mol%. The preferred range is 10 to 100 mol%, 30 to 97 mol%, 50 to 95 mol%, 60 to 93 mol%, 70 to 90 mol%, more preferably 75 to 85 mol% step by step. is there. If the proportion of the first diol unit (A1) is too small, an alloy may not be formed, and birefringence (or retardation) and moisture permeability may not be reduced. Furthermore, heat resistance may be reduced.

Second diol unit (A2)
The diol unit (A) may contain a second diol unit (A2) represented by the following formula (A2).

(In the formula, A ⁴ represents a linear or branched alkylene group, and r represents an integer of 1 or more).

In the formula (A2), the alkylene group A ⁴ is the same as the group A ¹ described in the section of the first diol unit (A1), including preferred embodiments.

The repeating number r of the oxyalkylene group (OA ⁴ ) may be selected from 1 or more, for example, an integer of about 1 to 10. As a preferable range, it is an integer of 1 to 5, an integer of 1 to 3, more preferably 1 or 2, and still more preferably 1 in a stepwise manner. If the number of repetitions r is too large, it may be difficult to reduce moisture permeability.

  Specific examples of the second diol unit (A2) include structural units derived from the second diol component (A2) such as alkanediol and polyalkylene glycol (or polyalkanediol).

Examples of the alkanediol include ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, tetramethylene glycol (1,4-butanediol), 1,5-pentanediol, Examples thereof include linear or branched C _2-12 alkanediols such as neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, and 1,10-decanediol.

Examples of the polyalkylene glycol (or polyalkane diol) include poly C _2-6 alkane diols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Among these polyalkylene glycols, di- to tetra-C _2-4 alkanediols such as diethylene glycol, triethylene glycol, and dipropylene glycol are preferable.

These 2nd diol units (A2) can also be utilized individually or in combination of 2 or more types. Of these second diol units (A2), preferably linear or branched C _2-6 alkanediols such as ethylene glycol, propylene glycol, 1,4-butanediol, more preferably linear or A unit derived from a branched C _2-4 alkanediol, particularly a linear or branched C _2-3 alkanediol such as ethylene glycol or propylene glycol, particularly ethylene glycol is preferred.

  The diol unit (A) may not contain the second diol unit (A2), but by containing such a second diol unit (A2), the polymerization reactivity is improved and the fluorene polyester is used. In general, the second diol unit (A2) is often included from the viewpoint that the mechanical properties (for example, flexibility) and moldability of the resin (or polymer alloy) can be improved. The ratio of the second diol unit (A2) is 0 to 100 mol% with respect to the entire diol unit (A), and can be selected from a range of, for example, about 0.1 to 99 mol%. In the following steps, 1 to 70 mol%, 3 to 50 mol%, preferably 5 to 40 mol%, 10 to 35 mol%, more preferably 12 to 30 mol%, particularly 15 to 25 mol% %.

  When the diol unit (A) includes the second diol unit (A2), the second diol unit (A2) may be used alone, but is usually used in combination with the first diol unit (A1). Many.

  The ratio of the total amount of the first diol unit (A1) and the second diol unit (A2) can be selected from a range of, for example, 10 mol% or more with respect to the entire diol unit (A). In a stepwise manner, it is 30 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, more preferably 90 mol% or more, and in particular, substantially 100 mol. %, Ie, only the first diol unit (A1) and / or the second diol unit (A2). Moreover, even if the ratio of the total amount of the 1st diol unit (A1) and the 2nd diol unit (A2) is selected from the range of about 30-100 mol% with respect to the whole diol unit (A), for example. Well, in the case where the ratio is not 100 mol%, the preferable range is 60 to 99.9 mol%, more preferably 80 to 99 mol%, and still more preferably 90 to 95 mol%.

  The ratio in the case of combining the first diol unit (A1) and the second diol unit (A2) is, for example, from the range of the former / the latter (molar ratio) = about 99.9 / 0.1 / 1/99. Preferred ranges are 99/1 to 30/70, 97/3 to 50/50, 95/5 to 60/40, and 90/10 to 65/35, and more preferably step by step. 88/12 to 70/30, more preferably 85/15 to 75/25.

Third diol unit (A3)
The diol unit (A) includes other diol units (third diol unit (A3) not belonging to the range of the first and second diol units) as long as the effects of the present invention are not impaired. You may go out. Examples of the third diol unit (A3) include alicyclic diols; aromatic diols (excluding the first diol component (A1)); and C _2-4 alkylene oxides (or the diol components) (or Units derived from the third diol component (A3) such as adducts (alkylene carbonate, haloalkanol) and the like can be mentioned.

  Examples of the alicyclic diol include cycloalkane diols such as cyclohexane diol; bis (hydroxyalkyl) cycloalkanes such as cyclohexane dimethanol; and hydrogenated aromatic diols such as hydrogenated bisphenol A described later. It is done.

  Examples of aromatic diols (excluding the first diol component (A1)) include dihydroxyarenes such as hydroquinone and resorcinol; araliphatic diols such as benzenedimethanol; bisphenol A, bisphenol F, bisphenol AD, and bisphenol Bisphenols such as C, bisphenol G, and bisphenol S; and biphenols such as p, p′-biphenol.

Moreover, as a _C2-4 alkylene oxide (or alkylene carbonate, haloalkanol) adduct of these alicyclic or aromatic diol components, for example, 1 mol of the alicyclic or aromatic diol component such as bisphenol A is used. On the other hand, adducts in which 2 to 10 moles of ethylene oxide are added may be mentioned.

  These 3rd diol units (A3) can also be used individually or in combination of 2 or more types. The diol unit (A) may contain the third diol unit (A3) alone, but usually it may contain the first diol unit (A1) and / or the second diol unit (A2). Many. The proportion of the third diol unit (A3) may be, for example, 90 mol% or less, preferably 30 mol% or less, more preferably 10 mol% or less, particularly with respect to the entire diol unit (A). 5 mol% or less. When the third diol unit (A3) is included, it may be, for example, 0.1 to 50 mol%.

(Dicarboxylic acid unit (B))
First dicarboxylic acid unit (B1)
The dicarboxylic acid unit (B) may contain a first dicarboxylic acid unit (B1) represented by the following formula (B1-1) or (B1-2).

(In the formula, R ³ is each independently a substituent, p and q are each independently an integer of 0 to 4, and A ² and A ³ are each independently a divalent which may have a substituent. Represents a hydrocarbon group).

In the formula (B1-1) or (B1-2), the substituent R ³ is the same as the group R ¹ exemplified in the section of the first diol unit (A1), and the substitution number p is the first This is the same as the number of substitutions k exemplified in the section of the diol unit (A1), including preferred embodiments.

Examples of the divalent hydrocarbon group represented by A ² and A ³ include a linear or branched alkylene group such as a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, 1, Examples include a linear or branched C _1-8 alkylene group such as a 2-butanediyl group and a 2-methylpropane-1,3-diyl group. Preferred hydrocarbon groups are linear or branched C _1-6 alkylene groups, more preferably linear chains such as methylene group, ethylene group, trimethylene group, propylene group, 2-methylpropane-1,3-diyl group. Or a branched C _1-4 alkylene group, particularly preferably a linear or branched C _1-3 alkylene group such as an ethylene group.

Examples of the substituent of the hydrocarbon group include an aryl group such as a phenyl group and a cycloalkyl group such as a cyclohexyl group. Examples of the hydrocarbon groups A ² and A ³ having a substituent include 1-phenylethylene group and 1-phenylpropane-1,2-diyl group.

The group A ² is often a linear or branched C _2-4 alkylene group, preferably a linear or branched C _2-3 alkylene group such as an ethylene group _{or a} propylene group, particularly an ethylene group. ). In many cases, the group A ³ is a linear or branched C _1-3 alkylene group, preferably a methylene group or an ethylene group. Note that the types of the ^two groups A2 may be different from each other and are usually the same.

  In the formula (B1-2), the repeating number q of the methylene group is, for example, an integer of about 0 to 3, preferably an integer of about 0 to 2, and more preferably 0 or 1.

As the dicarboxylic acid unit (B1) represented by the formula (B1-1), typically, for example, a unit in which A ² is a linear or branched C _2-6 alkylene group, specifically, 9,9-bis (carboxy C _2-6 alkyl) fluorene such as 9,9-bis (2-carboxyethyl) fluorene, 9,9-bis (2-carboxypropyl) fluorene, and ester forming properties thereof Examples thereof include a structural unit derived from the first dicarboxylic acid component (B1) such as a derivative.

As the dicarboxylic acid unit (B1) represented by the formula (B1-2), typically, for example, q is 0, and the group A ³ is a linear or branched C _1-6 alkylene group. A unit, specifically, for example, 9- (1,2-dicarboxyethyl) fluorene; q is 1 and the group A ³ is a linear or branched C _1-6 alkylene group. Derived from a first dicarboxylic acid component (B1) such as a compound, 9- (dicarboxy C _2-8 alkyl) fluorene such as 9- (2,3-dicarboxypropyl) fluorene; and their ester-forming derivatives And dicarboxylic acid units.

These first dicarboxylic acid units (B1) may be used alone or in combination of two or more. Of these first dicarboxylic acid units (B1), the dicarboxylic acid unit represented by the formula (B1-1) is preferable from the viewpoint of easily reducing birefringence, and among them, 9,9-bis (carboxyl). C _2-6 alkyl) fluorene, more preferably 9,9-bis (carboxy C _2-4 alkyl) fluorene, especially 9,9-bis (2-carboxyethyl) fluorene, 9,9-bis (2- Preferred are 9,9-bis (carboxy C _2-3 alkyl) fluorenes such as carboxypropyl) fluorene, especially dicarboxylic acid units derived from 9,9-bis (2-carboxyethyl) fluorene and their ester-forming derivatives. .

  The dicarboxylic acid unit (B) may not contain the first dicarboxylic acid unit (B1), but by containing the first dicarboxylic acid unit (B1), an alloy is formed with the aromatic polycarbonate resin. This is preferable because it can be easily performed and birefringence (or phase difference) can be reduced. The ratio of 1st dicarboxylic acid unit (B1) is 0-100 mol% with respect to the whole dicarboxylic acid unit (B), for example, may be selected from the range of about 1-99 mol%. Preferred ranges are 10 to 100 mol%, 30 to 100 mol%, 50 to 100 mol%, 60 to 100 mol%, 70 to 100 mol%, and 75 to 100 mol% in steps, and more preferably. Is preferably 80 to 100 mol%, more preferably 90 to 100 mol%, and particularly preferably 100 mol%, that is, substantially only the first dicarboxylic acid unit (B1). In addition, when the ratio of the first dicarboxylic acid unit (B1) is not 100 mol% with respect to the entire dicarboxylic acid unit (B), the ratio is selected from a range of about 30 to 95 mol%, for example. Preferably, it is 60-90 mol%, More preferably, it is 75-85 mol%.

Second dicarboxylic acid unit (B2)
The dicarboxylic acid unit (B) may contain a second dicarboxylic acid unit (B2) represented by the following formula (B2).

(Wherein Z ² is an aliphatic ring or arene ring, R ⁴ is a substituent, and s is an integer of 0 or more).

In the formula (B2), examples of the aliphatic ring represented by Z ² include a cycloalkane ring; a bridged cyclic cycloalkane ring; a cycloalkene ring; a bridged cyclic cycloalkene ring, and the like.

Examples of the cycloalkane ring include C _5-10 cycloalkane rings such as a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and a cyclooctane ring.

  Examples of the bridged cyclic cycloalkane ring include di- or tricycloalkane rings such as a decalin ring, a norbornane ring, an adamantane ring, and a tricyclodecane ring.

Examples of the cycloalkene ring include C _5-10 cycloalkene rings such as a cyclohexene ring.

  Examples of the bridged cyclic cycloalkene ring include di- or tricycloalkene rings such as a norbornene ring.

  Preferred examples of the aliphatic ring include a cycloalkane ring and a bridged cyclic cycloalkane ring. Among them, a cycloalkane ring such as a cyclohexane ring is preferable.

Examples of the arene ring (aromatic hydrocarbon ring) represented by Z ² include the same arene rings as the arene ring exemplified for the ring Z ¹ in the first diol unit (A1). Preferred arene ring, for example, a benzene ring, a naphthalene ring, include _{C 6-14} arene ring such as biphenyl ring, more preferably _{C 6-12} arene ring Among them, a benzene ring, a naphthalene ring _{C 6- A 10} arene ring, in particular a benzene ring.

Ring Z ² is preferably an aliphatic ring from the viewpoint of easily reducing birefringence (or retardation), and in particular, a C _5-10 cycloalkane ring such as a cyclohexane ring, more preferably C _5-8 cyclo. Alkane rings, particularly cyclohexane rings are preferred.

Examples of the substituent represented by R ⁴ include the same substituents including the group R ² described in the section of the first diol unit (A1) and preferred embodiments.

The number of substitutions s of the group R ⁴ can be selected according to the type of the ring Z ² , and may be an integer of about 0 to 6, for example. An integer of 0 to 2, more preferably 0 or 1, especially 0. When s is 2 or more, the types of the two or more groups R ⁴ may be the same or different from each other. Further, the substitution position of the group R ⁴ is not particularly limited, and may be substituted at a position other than the bonding position between the two carbonyl groups [—C (═O) —] and the ring Z ² .

The substitution position of the two carbonyl groups [—C (═O) —] is not particularly limited. For example, when the ring Z ² is a cyclohexane ring, the two carbonyl groups [—C (═O) —] are represented by 1 , 2 position, 1,3 position or 1,4 position may be substituted, especially 1,3 position or 1,4 position, especially 1,4 position It is preferable to do this. When ring Z ² is a benzene ring, the two carbonyl groups [—C (═O) —] may be substituted by any positional relationship of the o-position, the m-position, and the p-position. In particular, it is preferable to substitute in the positional relationship of m-position or p-position, particularly p-position.

The second dicarboxylic acid unit (B2) is a structural unit corresponding to the second dicarboxylic acid component (B2), and examples of the representative second dicarboxylic acid component (B2) include, for example, in the formula (B2) , An alicyclic dicarboxylic acid (B2-1) corresponding to a unit in which ring Z ² is an aliphatic ring; in the formula (B2), an arene dicarboxylic acid (B 2 -2) corresponding to a unit in which ring Z ² is an arene ring 2); and their ester-forming derivatives.

Examples of the alicyclic dicarboxylic acid (B2-1) corresponding to the unit in which the ring Z ² is an aliphatic ring include cycloalkane dicarboxylic acid, bridged cyclic cycloalkane dicarboxylic acid, cycloalkene dicarboxylic acid, bridged cyclic And cycloalkene dicarboxylic acid.

Examples of the cycloalkanedicarboxylic acid include C _5-10 cycloalkane-dicarboxylic acid such as 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.

  Examples of the bridged cyclic cycloalkanedicarboxylic acid include di- or tricycloalkanedicarboxylic acid such as decalin dicarboxylic acid, norbornane dicarboxylic acid, adamantane dicarboxylic acid, and tricyclodecane dicarboxylic acid.

Examples of the cycloalkene dicarboxylic acid include C _5-10 cycloalkene-dicarboxylic acid such as cyclohexene dicarboxylic acid.

  Examples of the bridged cyclic cycloalkene dicarboxylic acid include di- or tricycloalkene dicarboxylic acid such as norbornene dicarboxylic acid.

Examples of the arene dicarboxylic acids (B2-2) corresponding to the unit in which the ring Z ² is an arene ring include benzene dicarboxylic acids and polycyclic arene dicarboxylic acids.

  Examples of benzenedicarboxylic acids include benzenedicarboxylic acid and alkylbenzenedicarboxylic acid.

  Examples of benzenedicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, and the like.

Examples of the alkylbenzene dicarboxylic acid include C _1-4 alkyl-benzene dicarboxylic acid such as 5-methylisophthalic acid.

  Examples of the polycyclic arene dicarboxylic acids include condensed polycyclic arene dicarboxylic acids and ring-assembled arene dicarboxylic acids.

Examples of the condensed polycyclic arene dicarboxylic acid include naphthalene dicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; anthracene Dicarboxylic acid; condensed polycyclic C _10-24 arene-dicarboxylic acid such as phenanthrene dicarboxylic acid. A preferred condensed polycyclic arene dicarboxylic acid is a condensed polycyclic C _10-14 arene dicarboxylic acid.

Examples of the ring assembly arene dicarboxylic acid include bi C _6-10 arene dicarboxylic acid such as 2,2′-biphenyldicarboxylic acid, 3,3′-biphenyldicarboxylic acid, 4,4′-biphenyldicarboxylic acid, and the like. It is done.

These 2nd dicarboxylic acid units (B2) can also be used individually or in combination of 2 or more types. Of these second dicarboxylic acid units (B2), units derived from alicyclic dicarboxylic acids (B2-1) are preferred from the viewpoint of easy reduction of birefringence (or retardation), and among them, C ₅ Units derived from _-10 cycloalkane-dicarboxylic acids, in particular C _5-8 cycloalkane-dicarboxylic acids, in particular 1,4-cyclohexanedicarboxylic acid, are preferred.

  The dicarboxylic acid unit (B) may or may not contain the second dicarboxylic acid unit (B2). By including the second dicarboxylic acid unit (B2), birefringence (or phase difference) can be reduced while maintaining or improving (or not reducing) mechanical strength. The ratio of the 2nd dicarboxylic acid unit (B2) is 0-100 mol% with respect to the whole dicarboxylic acid unit (B), for example, can be selected from the range of about 1-99 mol%. The preferred range is about 10 to 100 mol%, 30 to 100 mol%, 50 to 100 mol%, 60 to 100 mol%, 70 to 100 mol%, and 75 to 100 mol% step by step. Preferably it is 80-100 mol%, More preferably, it is 90-100 mol%, It is preferable that it is comprised by only 100 mol%, ie, a 2nd dicarboxylic acid unit (B2) substantially. In addition, when the ratio of the second dicarboxylic acid unit (B2) is not 100 mol% with respect to the entire dicarboxylic acid unit (B), the ratio is selected from a range of about 30 to 95 mol%, for example. Preferably, it is 60-90 mol%, More preferably, it is 75-85 mol%.

Third dicarboxylic acid unit (B3)
In addition, if the dicarboxylic acid unit (B) is in a range that does not impair the effects of the present invention, the other dicarboxylic acid unit (third dicarboxylic acid unit (B3 that does not belong to the range of the first or second dicarboxylic acid unit) )) May be included. Examples of the third dicarboxylic acid unit (B3) include aromatic dicarboxylic acids (excluding the first or second dicarboxylic acid component); aliphatic dicarboxylic acids; and third esters such as ester-forming derivatives thereof. And dicarboxylic acid units derived from the dicarboxylic acid component (B3).

  Examples of the aromatic dicarboxylic acid (excluding the first or second dicarboxylic acid component) include diarylalkane dicarboxylic acid and diaryl ketone dicarboxylic acid.

Examples of the diarylalkanedicarboxylic acid include diC _6-10 aryl C _1-6 alkane-dicarboxylic acid such as 4,4′-diphenylmethanedicarboxylic acid.

Examples of the diaryl ketone dicarboxylic acid include di (C _6-10 aryl) ketone-dicarboxylic acid such as 4.4′-diphenyl ketone dicarboxylic acid.

  Examples of the aliphatic dicarboxylic acid include alkane dicarboxylic acid and unsaturated aliphatic dicarboxylic acid.

Examples of the alkanedicarboxylic acid include C _2-12 alkane-dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and decanedicarboxylic acid.

Examples of the unsaturated aliphatic dicarboxylic acid include C _2-10 alkene-dicarboxylic acid such as maleic acid, fumaric acid, and itaconic acid.

  These 3rd dicarboxylic acid units (B3) can also be used individually or in combination of 2 or more types. The dicarboxylic acid unit (B) may contain the third dicarboxylic acid unit (B3) alone, but usually the first dicarboxylic acid unit (B1) and / or the second dicarboxylic acid unit (B2). Is often included. The proportion of the third dicarboxylic acid unit (B3) may be, for example, 90 mol% or less, preferably 30 mol% or less, more preferably 10 mol% or less, based on the entire dicarboxylic acid unit (B). In particular, it is 5 mol% or less. When the third dicarboxylic acid unit (B3) is included, the ratio of the third dicarboxylic acid unit (B3) may be, for example, 0.1 to 50 mol% with respect to the entire dicarboxylic acid unit (B). Good.

  The fluorene polyester resin contains at least the fluorene unit such as the first diol unit (A1) and the first dicarboxylic acid unit (B1), particularly the first diol unit (A1). The ratio of the total amount of the fluorene unit, that is, the first diol unit (A1) and the first dicarboxylic acid unit (B1) is, for example, in the range of about 1 to 100 mol% of the fluorene polyester resin with respect to the entire structural unit. The preferred range is from 20 to 99.9 mol%, 40 to 99 mol%, 50 to 98 mol%, 70 to 97 mol%, 80 to 95 mol%, more preferably 85, step by step. -95 mol%, in particular, 88-92 mol%.

  The fluorene polyester resin may contain a combination of the first diol unit (A1) and the first dicarboxylic acid unit (B1). When combining these units, the ratio of the first diol unit (A1) to the first dicarboxylic acid unit (B1) is, for example, the former / the latter (molar ratio) = 1/99 to 99/1. The preferred range is 10/90 to 90/10, 15/85 to 80/20, 20/80 to 70/30, and more preferably 25/75 to 65/35, 30 in the following steps. / 70 to 60/40, more preferably 35/65 to 55/45, particularly 40/60 to 50/50.

Method for producing fluorene polyester resin and its characteristics The method for producing fluorene polyester resin may be performed by reacting the diol component (A) with the dicarboxylic acid component (B), and a conventional method such as a transesterification method or a direct polymerization method. It can be prepared by a melt polymerization method such as a solution polymerization method or an interfacial polymerization method, and a melt polymerization method is preferred. The reaction may be performed in the presence or absence of a solvent depending on the polymerization method.

  The use ratio (or charge ratio) of the diol component (A) and the dicarboxylic acid component (B) is usually the former / the latter (molar ratio) = for example, 1 / 1.2 to 1 / 0.8, preferably 1. /1.1 to 1 / 0.9. In addition, in reaction, you may make it react using the amount of each diol component (A) and dicarboxylic acid component (B) using each component etc. excessively as needed. For example, an alkanediol such as ethylene glycol that can be distilled from the reaction system [or the second diol component (A2)] is used in excess of the ratio (or introduction ratio) of the units introduced into the fluorene polyester resin. May be.

  The reaction may be performed in the presence of a catalyst. As the catalyst, a conventional esterification catalyst (or transesterification catalyst) such as a metal catalyst can be used. Examples of metal catalysts include alkali metals (sodium, etc.); alkaline earth metals (magnesium, calcium, barium, etc.), transition metals (manganese, zinc, cadmium, lead, cobalt, titanium, etc.); periodic table group 13 metals (Aluminum etc.); Metal compounds containing Periodic Table Group 14 metals (Germanium etc.); Periodic Table Group 15 metals (antimony etc.) are used. The metal compound may be, for example, an alkoxide, an organic acid salt (acetate, propionate, etc.), an inorganic acid salt (borate, carbonate, etc.), a metal oxide, etc., and these hydrates. It may be. Typical metal compounds include, for example, germanium compounds (eg, germanium dioxide, germanium hydroxide, germanium oxalate, germanium tetraethoxide, germanium-n-butoxide, etc.); antimony compounds (eg, antimony trioxide, antimony acetate) Titanium compounds (eg, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, titanium oxalate, potassium potassium oxalate); manganese compounds (manganese acetate, 4 water) Examples thereof include calcium compounds (calcium acetate monohydrate, etc.).

These catalysts can be used alone or in combination of two or more. When using a plurality of catalysts, each catalyst can be added according to the progress of the reaction. Of these catalysts, manganese acetate tetrahydrate, calcium acetate monohydrate, germanium dioxide and the like are preferable. The amount of the catalyst used is, for example, 0.01 × 10 ^{−4 to} 100 × 10 ⁻⁴ mol, preferably 0.1 × 10 ⁻⁴ to 40 × 10, with respect to 1 mol of the dicarboxylic acid component (B). ^-4 mol. Moreover, the usage-amount of a catalyst is 0.001-10 weight part with respect to 100 weight part of dicarboxylic acid components (B), Preferably it is 0.01-1 weight part.

In addition, the reaction may be stabilized with a heat stabilizer (for example, a phosphorus compound such as trimethyl phosphate, triethyl phosphate, triphenyl phosphate, phosphorous acid, trimethyl phosphite, triethyl phosphite) or an antioxidant as necessary. You may carry out in presence of an agent (or coloring prevention agent). The amount of the stabilizer used is, for example, 0.01 × 10 ^{−4 to} 100 × 10 ⁻⁴ mol, preferably 0.1 × 10 ⁻⁴ to 40 × with respect to 1 mol of the dicarboxylic acid component (B). 10 ^-4 mol. Moreover, the usage-amount of a stabilizer is 0.001-10 weight part with respect to 100 weight part of dicarboxylic acid components (B), Preferably it is 0.01-1 weight part.

The reaction may be usually performed in an inert gas atmosphere (for example, nitrogen; a rare gas such as helium or argon). The reaction can also be performed under reduced pressure (for example, about 1 × 10 ² to 1 × 10 ⁴ Pa). The reaction temperature can be selected according to the polymerization method. For example, the reaction temperature in the melt polymerization method is 150 to 300 ° C, preferably 180 to 290 ° C, more preferably 200 to 280 ° C.

  The glass transition temperature Tg of the fluorene polyester resin thus obtained can be selected, for example, from a range of about 100 to 200 ° C., for example, 110 to 170 ° C., preferably 115 to 150 ° C., more preferably 120 to 140 ° C. Especially, it is 120-130 degreeC. If the glass transition temperature Tg is too high, moldability may be reduced, and melt film formation may be difficult. If it is too low, heat resistance may be reduced.

  The weight average molecular weight Mw of the fluorene polyester resin can be measured by gel permeation chromatography (GPC) or the like, and can be selected from a range of, for example, about 20000 to 100000 in terms of polystyrene. A preferable range is 30000 to 80000, more preferably. Is 35000-60000, more preferably 40000-55000, in particular 42000-52000. If the weight average molecular weight Mw is too low, it may be difficult to form a thin film by stretching.

The refractive index anisotropy (or birefringence) of the fluorene polyester resin can be evaluated by birefringence (3-fold birefringence) of a stretched film obtained by uniaxially stretching a film formed of the polyester alone at a stretch ratio of 3 times. Good. The stretched film (glass transition temperature Tg + 10) ° C. and the stretched film prepared under stretching conditions of a stretching speed of 25 mm / min have a triple birefringence of, for example, −100 × 10 ⁻⁴ to +100 at a measurement temperature of 20 ° C. and a wavelength of 600 nm. The range can be selected from a range of about × 10 ⁻⁴ , and preferred ranges are −80 × 10 ⁻⁴ to + 60 × 10 ⁻⁴ , −70 × 10 ⁻⁴ to + 30 × 10 ⁻⁴ , −60 × 10 ⁻⁴ to + 20 × 10 ⁻⁴ , −50 × 10 ⁻⁴ to + 10 × 10 ⁻⁴ , −40 × 10 ^{−4 to} 0, more preferably −35 × 10 ⁻⁴ to ⁻¹⁰ × 10 ⁻⁴ , However, it is −30 × 10 ⁻⁴ to −20 × 10 ⁻⁴ . If the triple birefringence is too large on the plus side, birefringence (or phase difference) may not be reduced.

  The refractive index of the fluorene polyester resin can be selected from, for example, a range of about 1.55 to 1.7 at a temperature of 20 ° C. and a wavelength of 589 nm. A preferable range is 1.57 to 1.67 stepwise below. More preferably, it is 1.59-1.65, More preferably, it is 1.6-1.64.

  The Abbe number of the fluorene polyester resin is, for example, 30 or less, preferably 28 or less, and more preferably 27 or less at a temperature of 20 ° C. The Abbe number of the fluorene polyester resin is, for example, 17 to 30, preferably 19 to 26, and more preferably 20 to 25 at a temperature of 20 ° C.

  In the present specification and claims, the glass transition temperature Tg, the weight average molecular weight Mw, the triple birefringence, the refractive index, and the Abbe number can be measured by the methods described in Examples described later.

  Moreover, the said fluorene polyester resin can also be used individually or in combination of 2 or more types.

[Aromatic polycarbonate resin]
The aromatic polycarbonate resin can form a polymer alloy (particularly, a completely compatible polymer alloy) with the fluorene polyester resin.

  The aromatic polycarbonate resin is a polycarbonate resin having a diol component (C) as a polymerization component [that is, a polycarbonate resin having a diol unit (C) derived from the diol component (C)], and the diol component (C) [or diol The unit (C)] contains at least the aromatic diol component (C1) [or the aromatic diol unit (C1)].

As the aromatic diol component (C1), for example, the diol component exemplified as the first diol component (A1) in the section of the fluorene polyester resin; and the aromatic skeleton of the third diol component (A3) Examples thereof include diol components exemplified by aromatic diols, araliphatic diols, bisphenols, biphenols, and C _2-4 alkylene oxide (or alkylene carbonate, haloalkanol) adducts thereof. These aromatic diol components (C1) [or aromatic diol units (C1)] can be used alone or in combination of two or more. Among these aromatic diol components (C1), it is preferable that at least (bi- or bisphenols) or a C _2-4 alkylene oxide adduct thereof is included from the viewpoint of easily forming a polymer alloy with the fluorene polyester resin.

  Among the (bi or) bisphenols, examples of bisphenols include bis (hydroxyaryl) alkanes, bis (hydroxyaryl) -arylalkanes, bis (hydroxyaryl) cycloalkanes, and bis (hydroxyaryl) ethers. Bis (hydroxyaryl) ketones, bis (hydroxyaryl) sulfides, bis (hydroxyaryl) sulfoxides, bis (hydroxyaryl) sulfones and the like.

Examples of bis (hydroxyaryl) alkanes include bis (hydroxyaryl) alkanes and bis (alkyl-hydroxyaryl) alkanes. Examples of the bis (hydroxyaryl) alkane include bis (4-hydroxyphenyl) methane (bisphenol F), 1,1-bis (4-hydroxyphenyl) ethane (bisphenol AD), and 2,2-bis (4-hydroxy). Phenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) butane (bisphenol B), 2,2-bis (4-hydroxyphenyl)- Examples thereof include bis ( _{hydroxyC 6-12} aryl) C _1-6 alkane such as 3-methylbutane and 2,2-bis (4-hydroxy-3-phenylphenyl) propane.

Examples of the bis (alkyl-hydroxyaryl) alkane include 2,2-bis (4-hydroxy-3-methylphenyl) propane (bisphenol C) and 2,2-bis (4-hydroxy-3-isopropylphenyl). ) Bis (C _1-6 alkyl-hydroxy C _6-12 aryl) C _1-6 alkane such as propane (bisphenol G).

Examples of bis (hydroxyaryl) -arylalkanes include 1,1-bis (4-hydroxyphenyl) -1-phenylethane (bisphenol AP), bis (4-hydroxyphenyl) -diphenylmethane (bisphenol BP), and the like. Bis (hydroxy C _6-12 aryl)-(mono or di) C _6-12 aryl-C _1-6 alkane and the like.

Examples of bis (hydroxyaryl) cycloalkanes include 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z), 1,1-bis ( And bis ( _{hydroxyC 6-12} aryl) C _4-10 cycloalkane such as 4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (bisphenol TMC).

Examples of bis (hydroxyaryl) ethers include bis ( _{hydroxyC 6-12} aryl) ethers such as bis (4-hydroxyphenyl) ether.

Examples of bis (hydroxyaryl) ketones include bis ( _{hydroxyC 6-12} aryl) ketones such as bis (4-hydroxyphenyl) ketone.

Examples of the bis (hydroxyaryl) sulfides include bis ( _{hydroxyC 6-12} aryl) sulfides such as bis (4-hydroxyphenyl) sulfide.

Examples of the bis (hydroxyaryl) sulfoxides include bis (hydroxy C _6-12 aryl) sulfoxide such as bis (4-hydroxyphenyl) sulfoxide.

Examples of the bis (hydroxyaryl) sulfones include bis ( _{hydroxyC 6-12} aryl) sulfones such as bis (4-hydroxyphenyl) sulfone (bisphenol S).

Among (bi or) bisphenols, examples of bisphenols include dihydroxy-bi C _6-10 arenes such as o, o′-biphenol, m, m′-biphenol, p, p′-biphenol, and the like. .

The C _2-4 alkylene oxide adduct of these diol components is, for example, about 1 to 10 moles, preferably 1 to 5 moles of ethylene oxide with respect to 1 mole of the (bi- or) bisphenol (for example, bisphenol A). Examples include adducts obtained by molar addition. These (bi or) bisphenols or their C _2-4 alkylene oxide adducts can be used alone or in combination of two or more.

Of these (bi or) bisphenols or their C _2-4 alkylene oxide adducts, bisphenols are preferable, and bis (hydroxyaryl) alkanes, particularly bis ( _{hydroxyC 6-10} such as bisphenol A). Aryl) C _1-4 alkanes and the like are preferred. These preferable bisphenols can be used alone or in combination of two or more.

  The ratio of the aromatic diol unit (C1) can be selected, for example, from a range of 10 mol% or more with respect to the entire diol unit (C). % Or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, more preferably 90 mol% or more, especially 95 mol% or more, and in particular, substantially 100 mol%, that is, aromatic. It is preferably composed of only the diol unit (C1). Moreover, the ratio of the aromatic diol unit (C1) may be selected from the range of, for example, about 60 to 100 mol% with respect to the entire diol unit (C). 80-99 mol%, preferably 95-97 mol%. When the ratio of the aromatic diol unit (C1) is too small, it may be difficult to form a polymer alloy.

  Among the aromatic diol units (C1), the proportion of units derived from bisphenols can be selected, for example, from a range of 10 mol% or more with respect to the entire diol units (C). 30 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, more preferably 90 mol% or more, especially 95 mol% or more, Preferably, it is composed of only units derived from bisphenols. Therefore, bisphenol type polycarbonate resin is preferable as the aromatic polycarbonate resin. If the proportion of units derived from bisphenols is too small, it may be difficult to form a polymer alloy. Moreover, the ratio of the unit derived from bisphenols may be selected from the range of, for example, about 60 to 100 mol% with respect to the entire diol unit (C), and when the ratio is not 100 mol%, It is 80 to 99 mol%, preferably 95 to 97 mol%.

  Among the units derived from bisphenols, in particular, the proportion of units derived from bisphenol A can be selected from a range of, for example, 10 mol% or more with respect to the entire diol unit (C). Step by step, 30 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, more preferably 90 mol% or more, especially 95 mol% or more. In particular, it is preferably composed of 100 mol%, that is, only units derived from bisphenol A. Therefore, the aromatic polycarbonate resin is preferably a bisphenol type polycarbonate resin, and particularly preferably a bisphenol A type polycarbonate. If the proportion of units derived from bisphenol A is too small, it may be difficult to form a polymer alloy. Moreover, the ratio of the unit derived from bisphenol A may be selected from the range of, for example, about 60 to 100 mol% with respect to the entire diol unit (C). When the ratio is not 100 mol%, for example, It is 80 to 99 mol%, preferably 95 to 97 mol%.

In addition, the diol component (C) [or diol unit (C)] may contain another diol component (C2) [or diol unit (C2)] as long as the effects of the present invention are not impaired. As another diol component (C2), for example, in the section of the fluorene polyester resin, among the second diol component (A2) and the third diol component (A3), an alicyclic group having no aromatic skeleton Diol and diol components exemplified as C _2-4 alkylene oxide (or alkylene carbonate, haloalkanol) adducts thereof; poly (or oligo) ester diols having terminal hydroxyl groups such as polyethylene adipate; heterocyclic diols such as isosorbide, etc. Is mentioned.

  The ratio of the aromatic diol unit (C2) may be, for example, 50 mol% or less, preferably 30 mol% or less, more preferably 10 mol% or less, particularly with respect to the entire diol unit (C). 5 mol% or less. Moreover, 0.1 to 40 mol% may be sufficient as the said ratio, for example.

  The aromatic polycarbonate resin may be prepared by a conventional method such as a phosgene method using phosgene or a transesterification method using carbonates such as diphenyl carbonate, or a commercially available product may be procured.

  The glass transition temperature Tg of the aromatic polycarbonate resin can be selected from the range of about 100 to 250 ° C. (for example, 100 to 230 ° C.), for example, 110 to 200 ° C., preferably 120 to 180 ° C., and more preferably 130. About 160 degreeC (for example, 140-150 degreeC) may be sufficient. If the glass transition temperature Tg is too high, the moldability may decrease, and if it is too low, the heat resistance may decrease.

  The weight average molecular weight Mw of the aromatic polycarbonate resin can be measured by gel permeation chromatography (GPC) or the like, and can be selected from the range of, for example, about 8000 to 150,000 in terms of polystyrene. It is -100000, 15000-80000, 20000-70000, 30000-60000, More preferably, it is 35000-50000, Especially 40000-45000. If the molecular weight of the aromatic polycarbonate resin is within this range, not only the moldability is easily improved, but also the phase differences R0 and Rth can be reduced.

The triple birefringence of the aromatic polycarbonate resin is, for example, + 30 × at a measurement temperature of 20 ° C. and a wavelength of 600 nm using a stretched film prepared under stretching conditions (glass transition temperature Tg + 10) ° C. and stretching speed of 25 mm / min. It can be selected from the range of about 10 ⁻⁴ to + 350 × 10 ⁻⁴ , and preferred ranges are as follows: + 40 × 10 ⁻⁴ to + 300 × 10 ⁻⁴ , + 50 × 10 ⁻⁴ to + 250 × 10 ⁻⁴ , + 100 × 10 ⁻⁴ to + 200 × 10 ⁻⁴ , + 130 × 10 ⁻⁴ to + 180 × 10 ⁻⁴ , more preferably + 150 × 10 ⁻⁴ to + 170 × 10 ⁻⁴ .

  The refractive index of the aromatic polycarbonate resin is, for example, 1.55 to 1.65, preferably 1.56 to 1.62, and more preferably 1.58 to 1.6 at a temperature of 20 ° C. and a wavelength of 589 nm.

  The Abbe number of the aromatic polycarbonate resin is, for example, 40 or less, preferably 35 or less, and more preferably 33 or less at a temperature of 20 ° C. The Abbe number is, for example, 24-37, preferably 26-34, more preferably 28-32 at a temperature of 20 ° C.

  In addition, the said aromatic polycarbonate resin can also be used individually or in combination of 2 or more types.

[Preparation method and characteristics of polymer alloy]
Although the fluorene polyester resin and the aromatic polycarbonate resin are different types of polymers, the resin component becomes a completely compatible state or a stable microphase separation state when mixed, and even without using a compatibilizing agent, A polymer alloy can be easily formed. In the polymer alloy, the resin component is preferably in a completely compatible state.

  The ratio between the fluorene polyester resin and the aromatic polycarbonate resin can be selected, for example, from the range of the former / the latter (weight ratio) = 99/1 to 0.1 / 99.9. / 10 to 1/99, 70/30 to 1/99, 50/50 to 1/99, 40/60 to 2/98, not only reducing the phase difference, but also improving the light transmittance and productivity. From an easy viewpoint, 35/65 to 2/98, more preferably 30/70 to 3/97, still more preferably 20/80 to 5/95, especially 15/85 to 5/95, especially 12/88. ~ 8/92. If the proportion of the fluorene polyester resin is too small, birefringence (or retardation) may be difficult to reduce, and moldability may be reduced. In the present invention, even when the proportion of the fluorene polyester resin is relatively small, birefringence (or retardation) can be effectively reduced. On the other hand, when the ratio of the aromatic polycarbonate resin is too small, the refractive index of the polarizing plate protective film increases and the surface reflectance also increases, which may reduce the transmittance.

  In the polymer alloy, the ratio of the total amount of the fluorene polyester resin and the aromatic polycarbonate resin is, for example, 30% by weight or more with respect to the whole polymer alloy, and a preferable range is 50% by weight or more and 60% by weight in the following steps. % Or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, more preferably 95% by weight or more, and particularly substantially 100% by weight. Moreover, the ratio of the total amount of a fluorene polyester resin and an aromatic polycarbonate resin may be 50-100 weight%, 70-99 weight%, 90-100 weight% etc. with respect to the whole polymer alloy, for example. If the ratio of the total amount of the fluorene polyester resin and the aromatic polycarbonate resin is too small, various properties required for the polarizing film, such as low birefringence (or low retardation), low moisture permeability, high mechanical properties, thin film There is a risk that the thickness (or high moldability) may not be satisfied in a balanced manner.

  Moreover, since the polymer alloy is easily compatible with each other, it may have one glass transition temperature Tg. Therefore, the glass transition temperature Tg of the polymer alloy can be selected, for example, from a range of about 100 to 180 ° C., and a preferable range is 110 to 170 ° C., 120 to 160 ° C., more preferably 125 to 155, step by step. ° C, more preferably 130 to 150 ° C, particularly 135 to 145 ° C. If the glass transition temperature Tg is too high, the moldability may be reduced.

  The polymer alloy may have a single or a plurality of peaks (a plurality of peaks that may be derived from each component) in the molecular weight distribution, and the weight average molecular weight Mw of the polymer alloy is determined by gel permeation chromatography (GPC). ), And can be selected from the range of, for example, about 20000 to 100000 in terms of polystyrene, for example, 30000 to 80000, preferably 35000 to 60000, more preferably 40000 to 50000, and particularly 41000 to 46000. If the weight average molecular weight Mw is too low, it may be difficult to form a thin film by stretching.

  The polymer alloy may contain various additives as long as the effects of the present invention are not hindered. Examples of additives include flame retardants (inorganic flame retardants, organic flame retardants, colloidal flame retardants, etc.), stabilizers (antioxidants, ultraviolet absorbers (or light-resistant agents), heat stabilizers, etc.), charging Inhibitors, mold release agents (natural waxes, synthetic waxes, linear fatty acids or metal salts thereof, acid amides, etc.), slipperiness imparting agents (eg, silica, titanium oxide, calcium carbonate, clay, mica, kaolin) Inorganic fine particles such as; organic fine particles such as (meth) acrylic resins, styrene resins (cross-linked polystyrene resins, etc.), surfactants, anti-gelling agents, compatibilizers, and the like. These additives may be used alone or in combination of two or more.

  From the viewpoint of suppressing the deterioration of iodine in the polarizer (polarizing element or polarizing functional layer), it is preferable to add at least an ultraviolet absorber to the polymer alloy (or polarizing plate protective film). Examples of the ultraviolet absorber include benzophenones (for example, 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone); benzotriazoles [for example, 2- (benzotriazol-2-yl) -4, 6-di-t-butylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-pentylphenol, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-Methyl-1-phenylethyl) phenol, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6-[(2H-benzotriazol-2-yl)] phenol ] Etc.] etc. are mentioned. These ultraviolet absorbers may be used alone or in combination of two or more. By using such an ultraviolet absorber, ultraviolet rays having a wavelength of 380 nm or less can be blocked, for example, the light transmittance at a wavelength of 380 nm can be blocked to about 10% or less.

  These additives can be added by a conventional method, for example, a method of mixing by an extruder, etc., which may be added at the time of preparing the polymer alloy described later, or when preparing each resin component You may add to.

  Moreover, the mixing method (preparation method of polymer alloy) of each resin component (and additive) is not particularly limited, and a conventional method, for example, a method of dissolving both resin components in a solvent, a kneader (or an extruder, for example, , A twin-screw extruder, etc.) may be used. A melt-mixing method is preferred from the viewpoint of preventing deterioration of optical properties (for example, low birefringence, high transparency, etc.) due to the residual solvent after film formation.

  In the melt mixing, the temperature is, for example, 200 to 300 ° C, preferably 250 to 290 ° C. The ratio (L / D) between the effective screw length L and the screw diameter D (L / D) of the kneader (or extruder) is, for example, 20 to 40, preferably 25 to 35. The screw diameter D is, for example, 10 to 20 mm, preferably 12 to 18 mm. The rotation speed is, for example, 50 to 500 rpm, preferably 100 to 300 rpm.

[Preparation method and properties of polarizing plate protective film]
(Preparation of polarizing plate protective film)
The polarizing plate protective film of the present invention can be prepared by forming the polymer alloy and, if necessary, stretching the formed film. The film-forming method (or film-forming process) is not particularly limited. For example, a casting method (or a solution casting method, a solution casting method), an extrusion method (an inflation method, a T-die method, or other melt extrusion methods (or extrusion) Molding)), a melt extrusion method such as a T-die method is preferred from the viewpoint of not only being excellent in moldability but also capable of preventing deterioration of optical properties due to residual solvent. In the present invention, in order to form a polarizing plate protective film with a polymer alloy, or in spite of containing a fluorene polyester resin having a rigid fluorene skeleton or an aromatic polycarbonate resin having low moldability, a melt extrusion method (or It can be easily formed into a film and can be made into a thin film by melt film formation.

  Further, the polarizing plate protective film may be an unstretched film, but it may be a stretched film from the viewpoint that it is easy to make a thin film and a uniform film thickness by stretching, and mechanical properties can be improved. Many.

  The stretching treatment (or stretching step) is a uniaxial stretching that stretches in one direction such as a longitudinal direction (flow direction or MD direction), a transverse direction (width direction or TD direction), or an oblique direction, or a stretching in two longitudinal and transverse directions. Any of axial stretching may be used. Stretching (for example, uniaxial stretching) may be performed by a wet stretching method or a dry stretching method, and in biaxial stretching, a tenter method (flat method), a tube method, or the like can be used. Among these stretching methods, the biaxial stretching, particularly the tenter method is preferable from the viewpoint of easily suppressing the expression of birefringence or retardation (or retardation) due to stretching and being excellent in thickness uniformity. Biaxial stretching may be sequential biaxial stretching, but simultaneous biaxial stretching is preferable because it is easy to suppress an increase in retardation. In addition, the stretching ratio in the vertical and horizontal directions may be different depending on the direction (the vertical and horizontal strengths and shrinkage are different), but the vertical and horizontal stretching ratios are equal (in the vertical and horizontal directions) from the viewpoint that the expression of the phase difference can be effectively suppressed. Equal stretching (having equal strength and shrinkage) is preferred.

  Stretch molding (stretching process or stretching process) may be performed while heating. The stretching temperature can be selected from the range of, for example, (Tg-10) to (Tg + 50) ° C., where Tg is the glass transition temperature of the polymer alloy. ) To (Tg + 40) ° C., Tg to (Tg + 30) ° C., (Tg + 3) to (Tg + 20) ° C., and more preferably (Tg + 5) to (Tg + 15) ° C. As a specific temperature, for example, a preferable range of 130 to 190 ° C is 135 to 180 ° C, 140 to 170 ° C, 143 to 160 ° C, and more preferably 145 to 155 ° C step by step. If the stretching temperature is too high, the fluidity becomes too high, and the moldability and thickness uniformity may decrease. If the stretching temperature is too low, the film may not be stretched uniformly or may be broken, and birefringence (or retardation) may not be reduced. In addition, it seems that the direction of extending | stretching at comparatively high temperature has the high effect of reducing a phase difference.

  The draw ratio is, for example, 1.1 to 10 times, preferably 1.2 to 5 times, more preferably 1.2 to 3 times, and still more preferably 1 to 10 times in each direction of uniaxial stretching and biaxial stretching. 3 to 2 times, especially 1.3 to 1.8 times, especially 1.4 to 1.6 times. If the draw ratio is too low, there is a possibility that the film thickness or the thickness cannot be made uniform. If the draw ratio is too high, the film may be broken. However, because the polarizing plate protective film of the present invention is formed of the polymer alloy, it can be easily stretched even at a high magnification and can be easily made into a thin film.

  In addition, as long as the polarizing plate protective film does not impair the effect of this invention, you may laminate | stack another film (or coating layer) as needed. For example, a slippery layer may be formed by coating a surfactant, a release agent, or a polymer layer containing fine particles. Further, a surface treatment layer may be formed on the surface of the polarizing plate protective film. For example, a polarizer (or polarized light) may be formed by a conventional surface treatment such as corona discharge treatment, plasma treatment, flame treatment, ozone or ultraviolet irradiation treatment. You may form the easily bonding layer for adhere | attaching with a functional layer. Therefore, the polarizing plate including the polarizing functional layer (polarizer or polarizing element) and the polarizing plate protective film is obtained by combining the easy-adhesion layer and the polarizing functional layer with conventional adhesives such as polyvinyl alcohol and polyvinyl acetal ( Polyvinyl acetate adhesives such as polyvinyl butyral), acrylic resin adhesives such as polybutyl acrylate, epoxy resin adhesives such as alicyclic epoxy resins, preferably vinyl acetate adhesives, particularly polyvinyl alcohol It may be formed by bonding. The present invention also includes the polarizing plate thus obtained and an image display device including the polarizing plate.

(Characteristics of polarizing plate protective film)
Since the polarizing plate protective film obtained by the above method is formed using the polymer alloy, birefringence (or retardation) can be easily reduced, and rainbow unevenness, light leakage, and the like can be effectively suppressed. In addition, the moldability of the polymer alloy (fluidity, flexibility, dimensional stability, etc.) is surprisingly high, and the film can be easily thinned. For this reason, it is possible to sufficiently meet the recent demands for reducing the thickness of the polarizing plate protective film, for example, 50 μm or less, preferably 40 μm or less. Furthermore, since it is formed of the polymer alloy, the polarizing plate protective film has low moisture permeability even when the film thickness is thin, and is excellent in mechanical strength (tensile strength, toughness, impact resistance, etc.). And since it is excellent also in heat resistance (thermal stability), deterioration of a polarizer (polarization functional layer or polarizing element) by a water | moisture content, a heat | fever, and / or an impact can be suppressed effectively. Thus, the polarizing plate protective film of the present invention can satisfy various required characteristics in a balanced manner.

  The in-plane retardation (or front retardation) R0 and the thickness direction retardation Rth of the polarizing plate protective film can be calculated by the following equations, respectively.

R0 = (nx−ny) × d
Rth = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction of the film, ny is the refractive index in the fast axis direction of the film, nz is the refractive index in the film thickness direction, and d is the thickness of the film).

  The in-plane retardation (or front retardation) R0 of the polarizing plate protective film of the present invention can be selected from a range of, for example, about 0 to 150 nm at room temperature, a wavelength of 550 nm, and a thickness of 25 μm. Specifically, it is 0 to 100 nm, 0.01 to 90 nm, 0.1 to 80 nm, 0.5 to 70 nm, 1 to 60 nm, more preferably 3 to 55 nm, particularly 5 to 50 nm. If the in-plane retardation R0 is too large, rainbow unevenness and light leakage may not be suppressed when the polarizing plate protective film is viewed from the front.

  The thickness direction retardation Rth of the polarizing plate protective film can be selected from a range of, for example, about 0 to 350 nm at room temperature, a wavelength of 589 nm, and a thickness of 25 μm, and a preferable range is as follows. It is 1-330 nm, 10-320 nm, 50-310 nm, 100-305 nm, 150-300 nm, More preferably, it is 170-295 nm, Especially 180-290 nm. If the thickness direction retardation Rth is too large, rainbow unevenness and light leakage may not be suppressed when the polarizing plate protective film is viewed obliquely.

  Conventionally, as is clear from the description of Patent Document 1 ([0033]), for example, the in-plane retardation (or front retardation) R0 and the thickness direction retardation Rth are both 0 for the polarizing plate protective film. A transparent film having a thickness of about 10 nm is used. On the other hand, a transparent film such as a polycarbonate film cannot be used as a polarizing plate protective film because the retardation is too high at several hundred nm or more. However, the range where the retardation is between these films, for example, R0 at a wavelength of 550 nm and a thickness of 25 μm is about 5 to 150 nm, preferably 5 to 100 nm, more preferably 10 to 50 nm at room temperature. The existence of a transparent film corresponding to a range of Rth at a wavelength of 589 nm and a thickness of 25 μm of about 1 to 330 nm, preferably 10 to 300 nm, more preferably 50 to 300 nm, particularly 100 to 290 nm is not known. Was not specifically evaluated. In the polarizing plate protective film of the present invention, since R0 and Rth correspond to the above ranges, rainbow unevenness and light leakage can be effectively suppressed despite the fact that the retardation is higher than that of the conventional polarizing plate protective film. It was an unexpected result that it can be used as a plate protective film.

  The in-plane retardation (or front retardation) R0 and the thickness direction retardation Rth can be measured by the method described in Examples described later.

  The thickness (or average thickness) of the polarizing plate protective film can be selected, for example, from a range of about 5 to 100 μm, and preferred ranges are 5 to 80 μm, 10 to 50 μm, 12 to 45 μm, and 15 to 40 μm step by step. 18 to 35 μm, more preferably 20 to 30 μm, particularly 20 to 25 μm.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Evaluation methods and raw materials are shown below.

[Evaluation method]
(Glass transition temperature Tg)
It measured based on JISK7121 using the differential scanning calorimeter (The Seiko Instruments Co., Ltd. product, "DSC 6220").

(Average film thickness after stretching)
Using a thickness gauge ("Micrometer" manufactured by Mitutoyo Corporation), three points were measured at equal intervals between the chucks in the longitudinal direction of the film, and the average value was calculated.

(Molecular weight)
Using gel permeation chromatography (“HLC-8120GPC” manufactured by Tosoh Corporation), the sample was dissolved in chloroform, and the weight average molecular weight Mw was measured in terms of polystyrene.

(Refractive index)
Using a multiwavelength Abbe refractometer (“DR-M2 / 1550” manufactured by Atago Co., Ltd.), the measurement was performed at a measurement temperature of 20 ° C. and a wavelength of 589 nm.

(Abbe number)
Refractive indexes at wavelengths of 486 nm (F line), 589 nm (d line) and 656 nm (C line) at a measurement temperature of 20 ° C. using a multi-wavelength Abbe refractometer (“DR-M2 / 1550” manufactured by Atago Co., Ltd.) n _F , n _d and n _C were measured and calculated by the following formula.

_{(N d -1) / (n} F -n C).

(3 times birefringence)
The test piece used for the measurement of the triple birefringence was produced by press-molding a fluorene polyester resin at 160 to 240 ° C., and cutting out the obtained film (thickness 100 to 400 μm) into a strip shape of 15 mm × 50 mm. The test specimen for measurement was stretched 3 times at 25 mm / min at a glass transition temperature Tg + 10 ° C. to obtain a stretched film.

  Using a retardation measuring device ("RETS-100" manufactured by Otsuka Electronics Co., Ltd.), measure the retardation at a measurement temperature of 20 ° C. and a wavelength of 600 nm by a rotating analyzer method, and divide this retardation value by the thickness of the measurement site. Calculated with

(Phase difference)
An in-plane retardation R0 was measured under conditions of room temperature and wavelength of 550 nm using a phase difference meter ("RETS-100" manufactured by Otsuka Electronics Co., Ltd.), and thickness direction retardation Rth was measured under conditions of room temperature and wavelength of 589 nm. Was measured. A measured value shows the value converted into film thickness 25micrometer.

(Cross Nicol test)
The produced polarizing plate protective film was sandwiched between two PVA polarizers (polyvinyl alcohol polarizers) whose absorption axes were orthogonal to each other to obtain a laminated film having a three-layer structure. Using LED as a light source, light was applied to one surface of the laminated film, and the presence or absence of rainbow unevenness and light leakage was observed from the other surface side. Observation is the front direction with respect to the laminated film [direction in which the line connecting the observer (eyes) and the light source is substantially perpendicular to the laminated film] and the oblique direction [line connecting the observer (eyes) and the light source. In a direction oblique to the laminated film (for example, about 45 °). The observation results were evaluated according to the following criteria.

○: Rainbow unevenness and / or light leakage cannot be confirmed ×: Rainbow unevenness and / or light leakage can be confirmed.

[material]
BPEF: 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, manufactured by Osaka Gas Chemical Co., Ltd. EG: ethylene glycol, manufactured by Kanto Chemical Co., Ltd. CHDA: 1,4-cyclohexanedicarboxylic acid, Nikko Rica DMT: dimethyl terephthalate, manufactured by Kanto Chemical Co., Inc. FDP-m: 9,9-bis (2-methoxycarbonylethyl) fluorene [9,9-bis (2-carboxyethyl) fluorene (or fluorene-9) , 9-Dipropionic acid)], except that t-butyl acrylate described in Example 1 of JP-A-2005-89422 was changed to methyl acrylate [37.9 g (0.44 mol)]. Is synthesized in the same manner. PC1: Bisphenol A type polycarbonate resin, Mitsubishi Engineering Plastic Box Ltd., brand "Iupilon H-4000", glass transition temperature Tg: 144 ° C., a weight average molecular weight Mw: 42000, refractive index: 1.583, Abbe number: 30,3 Baifuku refraction: + 159 × 10 ^{- 4}
PC2: Bisphenol A type polycarbonate resin, manufactured by Mitsubishi Engineering Plastics, brand “Iupilon S-3000”, glass transition temperature Tg: 149 ° C., weight average molecular weight Mw: 54100, refractive index: 1.583, Abbe Number: 30, 3 times birefringence: + 269 × 10 ⁻⁴
PC3: Bisphenol A type polycarbonate resin, manufactured by Mitsubishi Engineering Plastics, brand “Iupilon E-2000”, glass transition temperature Tg: 152 ° C., weight average molecular weight Mw: 65700, refractive index: 1.583, Abbe Number: 30, 3 times birefringence: + 294 × 10 ⁻⁴ .

[Synthesis Example 1]
(Polymerization of fluorene polyester resin)
110 parts by weight of BPEF, 43 parts by weight of EG, and 54 parts by weight of CHDA were charged into a reaction vessel and dissolved, and then gradually heated to 230 ° C. with stirring to carry out an esterification reaction. After extracting a predetermined amount of water out of the system, 0.2 parts by weight of germanium oxide (manufactured by Kanto Chemical Co., Ltd.) as a polymerization catalyst and trimethyl phosphoric acid (manufactured by Kanto Chemical Co., Ltd.) as a coloring inhibitor 0. 2 parts by weight were added and heated under reduced pressure. After reaching 270 ° C. and 0.13 KPa, stirring was continued until a predetermined torque was reached. The polymer was extracted from the bottom of the can, and the strand passing through the water was cut to obtain resin pellets (fluorene polyester resin 1).

When the obtained pellet was analyzed by ¹ H-NMR, 80 mol% of the diol component introduced into the fluorene polyester resin 1 was derived from BPEF, and 20 mol% was derived from EG, and 100 of the introduced dicarboxylic acid component. Mole% was derived from CHDA. The glass transition temperature Tg of the fluorene polyester resin 1 was 121 ° C., the weight average molecular weight Mw was 46800, the refractive index was 1.607, the Abbe number was 27, and the triple birefringence was + 5 × 10 ⁻⁴ .

[Example 1]
(Production of resin composition and film)
As a polycarbonate resin, a raw material obtained by dry blending 90 parts by weight of dried pellets of PC1 and 10 parts by weight of dried pellets of fluorene polyester resin 1 was mixed with a twin-screw extruder (manufactured by Technobel Co., Ltd., model number "KZW15 / 45 ”, Screw diameter D = 15 mm, L / D = 32), and kneaded at a screw temperature of 280 ° C. and a rotation speed of 200 rpm to prepare pellets. The glass transition temperature of the obtained pellet was 140 ° C. The pellets were supplied to the biaxial extruder equipped with a T die, and a film having an effective width of 200 mm and a thickness of 50 μm was extruded and wound up as a roll.

(Production of stretched film)
A film piece of 70 mm × 70 mm is cut out from the film roll, mounted on a tenter type biaxial stretching apparatus (manufactured by Imoto Seisakusho), and simultaneously biaxial 1.4 × 1.4 times at Tg + 10 ° C. (= 150 ° C.). Stretched to prepare a stretched film. The average film thickness after stretching was 24 μm. The retardation of the obtained stretched film was measured, and a crossed Nicols test was performed.

[Examples 2-3]
Resin composition pellets, film and stretched film in the same manner as in Example 1 except that the blending ratio of PC1 and fluorene polyester resin 1 and stretching conditions (stretching ratio and stretching temperature) are changed as shown in Table 1. The physical properties were measured. The results are shown in Table 1.

[Synthesis Example 2]
Using 105 parts by weight of BPEF and 49 parts by weight of EG as the diol component, 66 parts by weight of DMT as the dicarboxylic acid component, 0.05 part by weight of manganese acetate tetrahydrate (manufactured by Kanto Chemical Co., Ltd.) as the transesterification catalyst and acetic acid 0.1 part by weight of calcium monohydrate (manufactured by Kanto Chemical Co., Inc.) was added, and the mixture was gradually heated to 230 ° C. with stirring to conduct a transesterification reaction. After extracting a predetermined amount of methanol out of the system, 0.2 parts by weight of germanium oxide (manufactured by Kanto Chemical Co., Ltd.) as a polymerization catalyst and trimethyl phosphoric acid (manufactured by Kanto Chemical Co., Ltd.) as a coloring inhibitor 0. 2 parts by weight were added and heated under reduced pressure. After reaching 270 ° C. and 0.13 KPa, stirring was continued until a predetermined torque was reached. The polymer was extracted from the bottom of the can, and the strand passing through the water was cut to obtain resin pellets (fluorene polyester resin 2).

When the obtained pellet was analyzed by ¹ H-NMR, 70 mol% of the diol component introduced into the fluorene polyester resin 2 was derived from BPEF, 30 mol% was derived from EG, and 100 of the introduced dicarboxylic acid component. Mole% was derived from DMT. The glass transition temperature Tg of the fluorene polyester resin 2 was 142 ° C., the weight average molecular weight Mw was 44000, the refractive index was 1.632, the Abbe number was 23, and the 3-fold birefringence was + 55 × 10 ⁻⁴ .

[Example 4]
Example except that 70 parts by weight of dried pellets of PC1 and 30 parts by weight of dried pellets of fluorene polyester resin 2 were used and the stretching conditions (stretching ratio and stretching temperature) were changed as shown in Table 1. In the same manner as in Example 1, pellets, a film, and a stretched film of a resin composition were prepared, and physical properties were measured. The results are shown in Table 1.

[Synthesis Example 3]
A fluorene polyester resin 3 was prepared in a pellet form in the same manner as in Synthesis Example 2 except that 86 parts by weight of BPEF and 33 parts by weight of EG were used as the diol component, and 83 parts by weight of FDP-m was used as the dicarboxylic acid component.

When the obtained pellet was analyzed by ¹ H-NMR, 80 mol% of the diol component introduced into the fluorene polyester resin 3 was derived from BPEF, and 20 mol% was derived from EG, and 100 of the introduced dicarboxylic acid component. The mol% was derived from FDP-m. The glass transition temperature Tg of the fluorene polyester resin 3 was 126 ° C., the weight average molecular weight Mw was 50000, the refractive index was 1.635, the Abbe number was 25, and the 3-fold birefringence was −26 × 10 ⁻⁴ .

[Examples 5 to 7]
Resin composition pellets, film, and stretched film in the same manner as in Example 1 except that the blending ratio of PC1 and fluorene polyester resin 3 and stretching conditions (stretching ratio and stretching temperature) are changed as shown in Table 1. The physical properties were measured. The results are shown in Table 1.

[Comparative Example 1]
A stretched film was produced in the same manner as in Example 1 except that a PC1 film was prepared without mixing the fluorene polyester resin, and the stretching conditions (stretching ratio and stretching temperature) were changed as shown in Table 1. Measurements were made. The results are shown in Table 1.

[Comparative Example 2]
A stretched film was produced in the same manner as in Example 1, except that a PC2 film was prepared without mixing the fluorene polyester resin, and the stretching conditions (stretching ratio and stretching temperature) were changed as shown in Table 1. Measurements were made. The results are shown in Table 1.

[Examples 8 to 9]
Resin in the same manner as in Example 1 except that PC2 was used instead of PC1 and the blending ratio of PC2 and fluorene polyester resin 1 and the stretching conditions (stretching ratio and stretching temperature) were changed as shown in Table 1. A pellet, a film and a stretched film of the composition were prepared and measured for physical properties. The results are shown in Table 1.

[Comparative Example 3]
A stretched film was produced in the same manner as in Example 1 except that a PC3 film was prepared without mixing the fluorene polyester resin, and the stretching conditions (stretching ratio and stretching temperature) were changed as shown in Table 1. Measurements were made. The results are shown in Table 1.

[Examples 10 to 11]
Resin in the same manner as in Example 1 except that PC3 was used instead of PC1 and the blending ratio of PC3 and fluorene polyester resin 1 and the stretching conditions (stretching ratio and stretching temperature) were changed as shown in Table 1. A pellet, a film and a stretched film of the composition were prepared and measured for physical properties. The results are shown in Table 1.

  As is clear from Table 1, both the in-plane retardation R0 and the thickness direction retardation Rth can be reduced in the example compared to the comparative example. Even if the in-plane retardation R0 was about 10 to 50 nm and the thickness direction retardation Rth was about 180 to 330 nm, the results of the crossed Nicols test were surprisingly good. Furthermore, the moldability was high and the film could be easily thinned.

  The polarizing plate protective film of the present invention can satisfy the required properties (low birefringence, low moisture permeability, high mechanical properties, thin film thickness, etc.) with respect to the polarizing plate protective film in a well-balanced manner. Furthermore, not only can the moldability be high and the film can be easily thinned, but it can be mass-produced by melt-extrusion film formation using an inexpensive material, resulting in great cost merit. Therefore, the said polarizing plate protective film is very useful as a polarizing plate containing this polarizing plate protective film and a polarizer. The polarizing plate is a device display (image display device), specifically, an FPD device (e.g. personal computer monitor, television, mobile phone (smartphone, etc.), tablet terminal, car navigation, touch panel, etc. For example, LCD, PDP, etc.).

Claims (15)

  Among the diol unit (A) and the dicarboxylic acid unit (B), at least one of the structural units is a unit having at least one fluorene skeleton selected from a fluorene-9,9-diyl skeleton and a fluoren-9-yl skeleton. A polarizing plate protective film comprising a polymer alloy comprising a fluorene polyester resin and an aromatic polycarbonate resin. The fluorene polyester resin contains at least one structural unit selected from the first diol unit (A1) and the first dicarboxylic acid unit (B1), and the first diol unit (A1) is represented by the following formula (A1) )

Wherein Z ¹ is independently an arene ring, R ¹ and R ² are each independently a substituent, A ¹ is each independently a linear or branched alkylene group, and k is each independently An integer of 0 to 4, m is each independently an integer of 0 or more, and n is each independently an integer of 1 or more.)
Wherein the first dicarboxylic acid unit (B1) is represented by the following formula (B1-1) or (B1-2):

(In the formula, R ³ is each independently a substituent, p and q are each independently an integer of 0 to 4, and A ² and A ³ are each independently a divalent which may have a substituent. Indicates a hydrocarbon group.)
The polarizing plate protective film according to claim 1, which is a structural unit represented by: In the formula (A1), Z ¹ is a C _6-10 arene ring, R ² is a C _1-4 alkyl group or a C _6-10 aryl group, A ¹ is a linear or branched C _2-4 alkylene group, k is an integer of 0 to 2, m is an integer of 0 to 2, n is an integer of 1 to 10,
The polarizing plate protective film according to claim 2, wherein in formula (B1-1), p is an integer of 0 to 2, and A ² is a linear or branched C _2-4 alkylene group.   The polarized light according to claim 2 or 3, wherein the ratio of the total amount of the first diol unit (A1) and the first dicarboxylic acid unit (B1) is 10 to 100 mol% with respect to the entire constituent units of the fluorene polyester resin. Board protection film. The fluorene polyester resin is represented by the following formula (A2)

(In the formula, A ⁴ represents a linear or branched alkylene group, and r represents an integer of 1 or more.)
The polarizing plate protective film in any one of Claims 1-4 containing the 2nd diol unit (A2) represented by these. Wherein in (A2), ^{A 4} is a linear or branched _{C 2-4} alkylene group, r is an integer of 1 to 3, the first diol units (A1) and the second diol unit (A2) The polarizing plate protective film according to claim 5, wherein the ratio is: former / latter (molar ratio) = 97 / 3-50 / 50. The fluorene polyester resin is represented by the following formula (B2)

(In the formula, Z ² represents an aliphatic ring or arene ring, R ⁴ represents a substituent, and s represents an integer of 0 or more.)
The polarizing plate protective film in any one of Claims 1-6 containing the 2nd dicarboxylic acid unit (B2) represented by these. In the formula (B2), Z ² is a C _5-10 cycloalkane ring or C _6-10 arene ring, R ⁴ is a C _1-4 alkyl group or a C _6-10 aryl group, and s is an integer of 0-4. ,
The polarizing plate protective film according to claim 7, wherein the ratio of the second dicarboxylic acid unit (B2) is 10 to 100 mol% with respect to the entire dicarboxylic acid unit (B).   The polarizing plate protective film according to claim 1, wherein the aromatic polycarbonate resin is a bisphenol-type polycarbonate resin.   The polarizing plate protective film according to any one of claims 1 to 9, wherein a ratio of the fluorene polyester resin and the aromatic polycarbonate resin is the former / the latter (weight ratio) = 50/50 to 1/99.   Thickness is 10-50 micrometers, The polarizing plate protective film in any one of Claims 1-10.   The in-plane retardation R0 at a wavelength of 550 nm and a thickness of 25 μm is 0 to 100 nm, and the thickness direction retardation Rth at a wavelength of 589 nm and a thickness of 25 μm is 0 to 300 nm. The polarizing plate protective film according to claim 1. .   The polarizing plate containing a polarizing functional layer and the polarizing plate protective film in any one of Claims 1-12.   Of the diol unit (A) and the dicarboxylic acid unit (B), at least one of the constituent units includes a fluorene-9,9-diyl skeleton or a unit having a fluoren-9-yl skeleton, and an aromatic polycarbonate resin. The manufacturing method of the polarizing plate protective film in any one of Claims 1-12 including the process of extruding the polymer alloy which has these.   The production method according to claim 14, further comprising a step of subjecting the film obtained by extrusion molding to uniaxial or biaxial stretching.