JPWO2019194111A1 - Polymers for retardation films, retardation films and their manufacturing methods and applications - Google Patents

Abstract

A diol (A) containing full orangeol (A1) represented by the following formula (1) and a dicarboxylic acid component (B) containing an alicyclic dicarboxylic acid (B1) having a trans compound ratio of 60 mol% or more are used. A retardation film containing a polyester resin contained as a polymerization component is produced. (In the formula, Z1 and Z2 show the same or different aromatic hydrocarbon rings, R1 and R2 show the same or different substituents, A1 and A2 show the same or different alkylene groups, R3. Indicates a substituent, m1 and m2 indicate the same or different integers of 0 or more, n1 and n2 indicate the same or different integers of 0 or 1 or more, and k represents an integer of 0 to 8. The obtained retardation film can achieve both reverse wavelength dispersion characteristics and thinning of the film.

Description

The present invention comprises a polymer containing a polyester resin that can be used for a retardation film used for a circularly polarizing plate having antireflection performance in a wide band, a retardation film formed of these polymers for retardation film, and their production. Regarding methods and uses.

In the circular polarizing plate, a 1/4 polarizing plate having a phase difference of 1/4 wavelength and a polarizing plate (linear polarizing plate) are provided so that the absorption axis of the polarizing plate is the slow axis of the 1/4 wavelength plate. It is formed by laminating so as to have an intersection angle of 45 °, and for example, in an image display device such as a reflective liquid crystal display device, a transflective liquid crystal display device, a touch panel display, or an organic electroluminescence (EL) display, the polarization state can be determined. It is used to control and display an image, or to absorb reflected light to ensure visibility. In particular, in recent years, with the installation of organic EL displays in smartphones, the importance of circularly polarizing plates has increased due to the need to prevent reflection of external light.

Since a general 1/4 wave plate functions for light of a specific wavelength, it may be colored by light outside the functioning wavelength range (for example, blue), or black display may be insufficient. Visibility tends to decrease. Therefore, there is a demand for a retardation film having a reverse wavelength dispersion characteristic in which the retardation is approximately 1/4 wavelength in a wide band of visible light. Further, although smartphones in recent years are required to be thinner, it is difficult to further reduce the thickness with a positive wavelength dispersive film that requires the use of two 1/4 wavelength retardation films, and one film. There is a demand for a reverse wavelength dispersive film that can be used in the above.

A general polymer exhibits a positive wavelength dispersion characteristic in which the phase difference decreases as the wavelength becomes longer, but as a polymer exhibiting an inverse wavelength dispersion characteristic, a structural unit in which the aromatic ring of the main chain and the aromatic ring of the side chain are orthogonal to each other. A film such as a copolymerized polycarbonate having (cardo structure) and a structural unit of an alicyclic hydrocarbon or a cyclic ether (oxygen-containing heterocycle) has been developed and used for a circular polarizing plate.

Japanese Patent Application Laid-Open No. 2010-134232 (Patent Document 1) describes the in-plane retardation values R450 and R550 of a polycarbonate copolymer having a bisphenylfluorene skeleton and a cyclic ether skeleton at wavelengths of 450 nm, 550 nm and 600 nm. And R600 are disclosed as optical films in which R450 <R550 <R600. In the examples of this document, an optical film is manufactured by uniaxially stretching an extruded film or a cast film at a draw ratio of 2 times.

Further, Japanese Patent Application Laid-Open No. 2012-31369 (Patent Document 2) describes a phase difference R450 formed of a polycarbonate resin containing a bisphenylfluorene skeleton and a cyclic ether skeleton and measured at a wavelength of 450 nm, and R550 measured at a wavelength of 550 nm. A transparent film having a ratio of 0.5 ≦ R450 / R550 ≦ 1.0 is disclosed. In the examples of this document, an optical film is manufactured by uniaxially stretching an extruded film at a stretching ratio of 1.2 to 2 times.

Further, Japanese Patent Application Laid-Open No. 2015-212368 (Patent Document 3) has a repeating structural unit including a bisfluorene skeleton, a cyclic ether skeleton, and an alicyclic hydrocarbon skeleton, and has a phase difference R450 and a wavelength at a wavelength of 450 nm. A transparent film containing a polycondensation resin having a ratio of 0.75 ≦ R450 / R550 ≦ 0.93 with a phase difference R550 at 550 nm is disclosed. In the examples of this document, a retardation film is produced by uniaxially stretching a hot press sheet or an extruded film at a draw ratio of 1.5 to 2 times.

Copolymerized polyester films have also been developed, and Japanese Patent Application Laid-Open No. 2015-200887 (Patent Document 4) describes a polyester copolymer having a bisphenylfluorene skeleton and an alicyclic skeleton and having wavelengths of 450 nm, 550 nm and 600 nm. There is disclosed an optical film in which the in-plane retardation values R450, R550 and R600 are R450 <R550 <R600. In the examples of this document, an optical film is produced by uniaxially stretching an extruded film or a cast film at a stretching ratio of 2 to 4 times.

Japanese Unexamined Patent Publication No. 2010-134232 Japanese Unexamined Patent Publication No. 2012-31369 Japanese Unexamined Patent Publication No. 2015-21268 JP-A-2015-200887

In recent years, organic EL displays are expected as flexible and foldable displays for applications such as smartphones and tablets. In such applications, it is necessary to reduce the overall thickness from the viewpoint of improving bendability and preventing warping, and there is also a demand for thinner circular polarizing plates.

However, in the above-mentioned retardation film, with respect to the demand for further thinning of the circularly polarizing plate, the phase difference of the 1/4 wavelength retardation film is proportional to the film thickness, and the thinness of the film and the phase difference Is in a trade-off relationship, so it is not easy to achieve both. In particular, since the fluorene skeleton is bulky and rigid, it is particularly difficult to control the stretching of the resin containing the fluorene skeleton.

Therefore, an object of the present invention is to provide a polymer capable of preparing a retardation film capable of achieving both inverse wavelength dispersibility and thinning of the film, a retardation film formed of this polymer, and a method and application thereof. is there.

Another object of the present invention is to provide a polymer capable of preparing a retardation film having high heat resistance, a retardation film formed of this polymer, and a method and application for producing the same.

As a result of diligent studies to achieve the above problems, the present inventors have made a polymer containing a polyester resin containing a specific fluorangeol as a diol component and a alicyclic dicarboxylic acid having a high trans-form ratio as a dicarboxylic acid component. The present invention has been completed by finding that the inverse wavelength dispersion characteristic and the thinning of the film can be achieved at the same time by preparing the retardation film in the above.

That is, the polymer for a retardation film of the present invention contains a diol (A) containing fluorangeol (A1) represented by the following formula (1) and a dicarboxylic acid component (B1) containing an alicyclic dicarboxylic acid (B1). ) Is included as a polymerization component, and the trans-form ratio of the alicyclic dicarboxylic acids (B1) is 60 mol% or more of the total dicarboxylic acid component (B).

(In the formula, Z ¹ and Z ² show the same or different aromatic hydrocarbon rings, R ¹ and R ² show the same or different substituents, and A ¹ and A ² show the same or different different. Indicates an alkylene group, R ³ indicates a substituent, m1 and m2 indicate the same or different integers of 0 or more, n1 and n2 indicate the same or different integers of 0 or more, and k indicates 0. Indicates an integer of ~ 8)

The diol (A) may further contain an aliphatic diol (A2). The molar ratio of the full orange all (A1) to the aliphatic diol (A2) may be the former / the latter = 99/1 to 10/90. The dicarboxylic acid component (B) may further contain an aromatic dicarboxylic acid component (B2). The polymer may be a polymer alloy of the polyester resin and the polycarbonate resin. The polymer may have a weight average molecular weight of 30,000 to 200,000.

The present invention also includes a retardation film obtained by stretching and molding the above-mentioned retardation film polymer. The average thickness of this retardation film may be 100 μm or less.

The present invention also includes a method for producing the retardation film, which includes a film forming step of obtaining a film by extrusion molding or solution casting molding, and a stretching step of stretching the film obtained in the film forming step. The stretching ratio in the stretching step may be 2 to 5 times.

The present invention also includes a circularly polarizing plate in which the retardation film and a polarizer are laminated. The present invention also includes an image display device provided with the circularly polarizing plate. This image display device may be an organic EL display.

In the present specification and the scope of patent claims, the "dicarboxylic acid component" and "dicarboxylic acids" are, in addition to dicarboxylic acids, dicarboxylic acid _{esters such as dicarboxylic acid C 1-3} alkyl esters, dicarboxylic acid halides, and dicarboxylic acids. It is used to mean including an ester-forming derivative such as an acid anhydride. The "ester-forming derivative" may be a monoester (half ester) or a diester.

Further, 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. For example, "C ₁ alkyl group" means an alkyl group having 1 carbon atom, and "C _6-10 aryl group" means an aryl group having 6 to 10 carbon atoms.

Further, in the present specification and the scope of patent claims, a "polymer alloy" is a mixture (or admixture) in which a plurality of polymers (or polymers, 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.

Further, in the present specification and claims, the in-plane phase difference measured in a specific wavelength region may be indicated by R450, R550, or the like. That is, the in-plane phase difference measured at a wavelength of 450 nm means “R450”, and the in-plane phase difference measured at a wavelength of 550 nm means “R550”.

In the present invention, the retardation film is prepared with a polymer containing a diol having a specific fluorene skeleton as a diol and a polyester resin containing a alicyclic dicarboxylic acid having a high trans-form ratio as a dicarboxylic acid component. Both the wavelength dispersion characteristic and the thinning of the film can be achieved. Further, the heat resistance of the retardation film can be improved.

The polymer for a retardation film of the present invention has a diol (A) containing a fluorinol (A1) represented by the above formula (1) and a dicarboxylic acid component (B) containing an alicyclic dicarboxylic acid component (B1). Contains a polyester resin containing and as a polymerization component.

[(A1) Full Orange All]
The diol (A) contains a full orange all (A1) represented by the above formula (1). In the above formula (1), the ^{aromatic hydrocarbon ring (arene ring) represented by Z 1} and Z ^{2 includes a} monocyclic aromatic hydrocarbon ring (monocyclic arene ring) such as a benzene ring and a polycycle. Examples thereof include a formula aromatic hydrocarbon ring (polycyclic arene ring). Examples of the polycyclic aromatic hydrocarbon ring include a condensed polycyclic aromatic hydrocarbon ring (condensed polycyclic arene ring) and a ring-assembled aromatic hydrocarbon ring (ring-assembled arene ring).

Examples of the condensed polycyclic arene ring include a condensed bicyclic arene ring, a condensed tricyclic arene ring, and the like. Examples of the fused bicyclic arene ring include a condensed bicyclic C _10-16 arene ring such as a naphthalene ring. Examples of the fused tricyclic arene ring include an anthracene ring and a phenanthrene ring.

Examples of the ring-set arene ring include _{a beerene ring such as a bi-C 6-12} arene ring, a tellerene ring such as a tel C _6-12 arene ring, and the like. Examples of the bi-C _6-12 arene ring include a biphenyl ring; a binaphthyl ring; a phenylnaphthalene ring such as a 1-phenylnaphthalene ring and a 2-phenylnaphthalene ring, and the like. Examples of the tel C _6-12 arene ring include a terphenylene ring.

_{Among these aromatic hydrocarbon rings, a C 6-12} arene ring such as a benzene ring, a naphthalene ring, and a biphenyl ring is preferable, and a C _6-10 arene ring such as a benzene ring is particularly preferable.

In the above formula (1), ^{examples of the substituent represented by R 3} include a hydrocarbon group such as an alkyl group and an aryl group, a cyano group, a halogen atom and the like. _{Examples of the alkyl group include a linear or branched C 1-6} alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and a t-butyl group. Examples of the aryl group include a C _6-10 aryl group such as a phenyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom. Of these substituents, an alkyl group, a cyano group, and a halogen atom are preferable, and a linear or branched C _1-4 alkyl group is particularly preferable. Further, among the linear or branched C _1-4 alkyl groups, a C _1-3 alkyl group is preferable, and a C _1-2 alkyl group such as a methyl group is particularly preferable.

The substitution number k of R ³ is an integer of 0 to 8, and the preferable range is an integer of 0 to 6, an integer of 0 to 4, and 0 to 2, with 0 being the most preferable. When k is 2 or more, ^{the types of R 3} may be the same or different from each other. Further, when k is 2 or more, two or more kinds of R ³ to be substituted with the same benzene ring may be the same or different from each other. The substitution position of R ³ is not particularly limited, and may be, for example, any of the 2nd to 7th positions of the fluorene ring, and is usually any of the 2nd, 3rd, and 7th positions.

In the above formula (1), the ^{substituents represented by R 1} and R ² include a halogen atom, a hydrocarbon group, an alkoxy group, a cycloalkyloxy group, an aryloxy group, an aralkyloxy group, an alkylthio group and a cycloalkylthio group. , Arylthio group, aralkylthio group, acyl group, nitro group, cyano group, substituted amino group and the like.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group. _{Alkyl groups include linear or branched C 1-10} alkyl such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, isobutyl group and t-butyl group. Examples thereof include a group, preferably a linear or branched C _1-6 alkyl group, and more preferably a linear or branched C _1-4 alkyl group. Examples of the cycloalkyl _{group include a C 5-10} cycloalkyl group such as a cyclopentyl group and a cyclohexyl group. Examples of the aryl group include _{a C 6-12} aryl group such as a phenyl group, an alkylphenyl group, a biphenylyl group and a naphthyl group. Examples of the alkylphenyl group include a methylphenyl group (tolyl group) and a dimethylphenyl group (xylyl group). Examples of the _{aralkyl group include a C 6-10} aryl-C _1-4 alkyl group such as a benzyl group and a phenethyl group.

Examples of the alkoxy group include a _{linear or branched C 1-10} alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, an isobutoxy group, and a t-butoxy group. Examples of the cycloalkyloxy _{group include a C 5-10} cycloalkyloxy group such as a cyclohexyloxy group. Examples of the aryloxy group include a _C6-10 aryloxy group such as a phenoxy group. Examples of the aralkyloxy group include a C _6-10 aryl-C _1-4 alkyloxy group such as a benzyloxy group. Examples of the alkylthio group include _{a C 1-10} alkylthio group such as a methylthio group, an ethylthio group, a propylthio group, an n-butylthio group and a t-butylthio group. Examples of the cycloalkylthio _{group include a C 5-10} cycloalkylthio group such as a cyclohexylthio group. Examples of the arylthio group include a _C6-10 arylthio group such as a thiophenoxy group. Examples of the aralkylthio group include a C _6-10 aryl-C _1-4 alkylthio group such as a benzylthio group. Examples of the acyl group include _{a C 1-6} acyl group such as an acetyl group. Examples of the substituted amino group include a dialkylamino group and a bis (alkylcarbonyl) amino group. Examples of the _{dialkylamino group include a diC 1-4} alkylamino group such as a dimethylamino group. Examples of the bis (alkylcarbonyl) amino group include a bis (C _1-4 alkyl-carbonyl) amino group such as a diacetylamino group.

Among these substituents, typical examples include a halogen atom; a hydrocarbon group such as an alkyl group, a cycloalkyl group, and an aralkyl group; an alkoxy group; an acyl group; a nitro group; a cyano group; and a substituted amino group. Preferred R ¹ and R ² include an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group and the like, and examples of the alkyl group include a linear or branched C _1-6 alkyl group such as a methyl group. Examples of the cycloalkyl group include C _5-8 cycloalkyl groups such as cyclohexyl groups, examples of aryl groups include C _6-14 aryl groups such as phenyl groups, and examples of alkoxy groups include C 6-14 aryl groups. Examples thereof include linear or branched C _1-4 alkoxy groups such as methoxy groups. In particular, examples of the alkyl group include a _{linear or branched C 1-4} alkyl group such as a methyl group.

R ¹ and substituents which m1 and m2 of ^{R 2} may be any integer of 0 or more, can be appropriately selected depending on the kind of ^{Z 1} and ^{Z 2,} respectively, for example, be an integer from 0 to 8, The preferred substitution numbers m1 and m2 are, step by step, an integer of 0 to 4, an integer of 0 to 3, an integer of 0 to 2, 0 or 1, and 0 is the most preferable. Also, if the replacement number m1 or m2 is 2 or more, two or more kinds of R ¹ or R ² may be the same or different. In particular, if m1 and m2 are 1, ^{Z 1} and ^{Z 2} is a benzene ring, a naphthalene ring or biphenyl ring, that ^{R 1} and ^{R 2} are methyl group. The substitution positions of R ¹ and R ² are not particularly limited, ^{and may be substituted at positions other than the bonding positions of Z 1} and Z ² and the 9-position of the ether bond (−O−) and the fluorene ring. ..

In the above formula (1), A ¹ and A ² are linear or branched such as ethylene group, propylene group (1,2-propanediyl group), trimethylene group, 1,2-butandyl group and tetramethylene group. Examples thereof include a chain C _{2-6 alkylene group.} Of these, a linear or branched C _2-3 alkylene group is preferable, a linear or branched C _2-3 alkylene group is more preferable, and an ethylene group is most preferable.

The number of repetitions (number of added moles) n1 and n2 of the oxyalkylene group (OA ¹ ) and the oxyalkylene group (OA ² ) may be integers of 0 or more, respectively, and may be, for example, 0 to 15, which is preferable repetition. The numbers n1 and n2 are integers of 0 to 10, 0 to 8, 0 to 6, 1 to 4, 1 to 2 in a stepwise manner, and most preferably 1. In the present specification and claims, the "repetition number (additional number of moles)" may be an average value (arithmetic mean value, arithmetic mean value) or an average number of additional moles, and a preferred embodiment is Similar to the preferred range of integers. If the repetition numbers n1 and n2 are too large, the refractive index of the resin may decrease. When n1 or n2 is 2 or more, the 2 or more oxyalkylene groups (OA ¹ ) or oxyalkylene groups (OA ² ) may be the same or different, respectively. Further, the oxyalkylene group (OA ¹ ) and the oxyalkylene group (OA ² ) may be the same as each other or may be different from each other.

In the above formula (1), ^{the substitution positions of the group [−O− (A 1} O) _n1 −H] and the group [−O− (A ² O) _n2 −H] are not particularly limited, and Z ¹ and Z ^It suffices to replace each of the appropriate replacement positions in 2. The substitution positions of the groups [−O− (A ¹ O) _n1 −H] and the groups [−O− (A ² O) _n2 −H] are 9 of the fluorene ring when ^{Z 1} and Z ^{2 are benzene rings.} In many cases, the phenyl group bonded to the position is at the 2-position, 3-position, 4-position, particularly at any of the 3-position or 4-position, and most preferably at the 4-position.

The fluorene all represented by the formula (1) is, for example, the fluorene all having k = 0, n1 = 0, n2 = 0 in the formula (1), that is, 9,9-bis (hydroxyl). Aryl) fluorenes; fluorenes having k = 0, n1 and n2 of 1 or more, preferably 1 to 10, such as 9,9-bis [hydroxy (poly) alkoxyaryl] fluorenes. In the present specification and claims, unless otherwise specified, "(poly) alkoxy" is used to mean including both an alkoxy group and a polyalkoxy group.

As 9,9-bis (hydroxyaryl) fluorenes, 9,9-bis (hydroxyphenyl) fluorene such as 9,9-bis (4-hydroxyphenyl) fluorene; 9,9-bis (4-hydroxy-3) 9,9-bis (hydroxy) such as −methylphenyl) fluorene, 9,9-bis (4-hydroxy-3-isopropylphenyl) fluorene, 9,9-bis (4-hydroxy-3,5-dimethylphenyl) fluorene, etc. -(Mono or di) C _1-4 alkyl-phenyl) fluorene; 9,9-bis (6-hydroxy-2-naphthyl) fluorene, 9,9-bis (6-hydroxy-1-naphthyl) fluorene, 9, 9,9-bis (hydroxynaphthyl) fluorene such as 9-bis (5-hydroxy-1-naphthyl) fluorene; 9,9-bis (4-hydroxy-3-phenylphenyl) fluorene such as 9,9-bis (4-hydroxy-3-phenylphenyl) Hydroxyphenylphenyl) Fluolene and the like can be mentioned.

Examples of 9,9-bis [hydroxy (poly) alkoxyaryl] fluorenes include 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene and 9,9-bis [4- (2- (2- (2-) 2- (2-) _{9,9-bis [hydroxy (mono or deca) C 2-4} alkoxy-phenyl] fluorene such as hydroxyethoxy) ethoxy) phenyl] fluorene; 9,9-bis [4- (2-hydroxyethoxy) -3-methyl Phenyl] fluorene, 9,9-bis [4- (2- (2-hydroxyethoxy) ethoxy) -3-isopropylphenyl] fluorene, 9,9-bis [4- (2-hydroxypropoxy) -3,5- 9,9-bis [hydroxy (mono or deca) C _2-4 alkoxy- (mono or di) C _1-4 alkyl-phenyl] fluorene such as dimethylphenyl] fluorene; 9,9-bis [6- (2- (2-) _{9,9-bis [hydroxy (mono or deca) C 2-4} alkoxy-naphthyl] fluorene such as hydroxyethoxy) -2-naphthyl] fluorene; 9,9-bis [4- (2-hydroxyethoxy) -3- Examples thereof include 9,9-bis [hydroxy (mono or deca) C _2-4 alkoxy-phenylphenyl] fluorene such as phenylphenyl] fluorene.

These full orange oars represented by the above formula (1) can be used alone or in combination of two or more. _{Of these fluorangeols, 9,9-bis (hydroxy- (mono or di) C 1-4} alkyl-phenyl) fluorene, such as 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 9 , 9-Bis [Hydroxy (mono or deca) C _2-4 Alkoxy C _6-10 aryl] Fluorene and other 9,9-bis [Hydroxy (poly) alkoxyaryl] fluorenes are preferable, and 9,9-bis [Hydroxy] (Mono or penta) C _2-4 alkoxy-phenyl] fluorene is more preferred, and 9,9-bis [hydroxy (mono or di) C such as 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene. _2-3 Alkoxy-Phenyl] Fluolene is most preferred.

[(A2) Aliphatic diol]
The diol (A) may further contain an aliphatic diol (A2) in addition to the full orange all (A1) represented by the formula (1) from the viewpoint of moldability and the like.

Examples of aliphatic diols include ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, tetramethylene glycol (1,4-butanediol), 1,5-pentanediol, and neo. _{Examples thereof include linear or branched C 2-12} alkanediols such as pentylene glycol, 1,6-hexanediol, 1,8-octanediol and 1,10-decanediol. These aliphatic diols can be used alone or in combination of two or more.

Of these, linear or branched C _2-6 alkane diols are preferable, and linear or branched C _2-4 alkane diols such as ethylene glycol, propylene glycol and 1,4-butanediol are more preferable. , Ethylene glycol, propylene glycol and other linear or branched C _2-3 alkanediols are more preferred, and ethylene glycol is most preferred.

The molar ratio of the full orange all (A1) unit and the aliphatic diol (A2) unit in the resin can be selected from the range of the former / the latter = 99/1 to 10/90, and the preferred range is as follows. Gradually, 97/3 to 20/80, 95/5 to 30/70, 90/10 to 50/50, 85/15 to 60/40, 80/20 / to 65/35, and 75/25. ~ 70/30 is the most preferable. If the proportion of the aliphatic diol (A2) is too small, the effect of improving moldability may not be exhibited, and if it is too large, it may be difficult to achieve both reverse wavelength dispersibility and thinning.

[(A3) Other diols]
The diol (A) may further contain other diols such as polyalkylene glycol, alicyclic diol, complex alicyclic diol, and aromatic diol.

Examples of the polyalkylene glycol (or polyalkanediol) include polyC _2-6 alkanediols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Examples of the alicyclic diol include cycloalkane diols such as cyclohexanediol; bis (hydroxyalkyl) cycloalkanes such as cyclohexanedimethanol; and hydrogenated aromatic diols described below such as hydrogenated bisphenol A.

Examples of the heteroalicyclic diol (heterocyclic diol) include isosorbide, isomannide, isoidet, and derivatives such as alkyl substituents thereof.

Examples of aromatic diols include dihydroxyarenes such as hydroquinone and resorcinol; aromatic aliphatic diols such as benzenedimethanol; bisphenols such as bisphenol F, bisphenol AD, bisphenol A, bisphenol C, bisphenol G, and bisphenol S; p, p' -Biphenols such as biphenols can be mentioned. The aromatic diol may be a C _2-4 alkylene oxide, a C _2-4 alkylene-carbonate or a halo C _2-4 alkanol adduct. Examples of such an adduct include an adduct in which 2 to 10 mol of ethylene oxide is added to 1 mol of bisphenol A.

These other diols can be used alone or in combination of two or more. _{Of these, di or tetra C 2-4} alkane diols such as diethylene glycol, triethylene glycol and dipropylene glycol; oxygen-containing heteroalicyclic diols such as isosorbide (oxygen-containing heterocyclic diols) are preferable.

The proportion of the other diol (A3) in the resin may be 30 mol% or less, preferably 20 mol% or less, and more preferably 10 mol% or less in the diol (A).

[(B1) Alicyclic dicarboxylic acids]
The dicarboxylic acid component (B) contains alicyclic dicarboxylic acids (B1). In the present invention, the trans-form ratio of the alicyclic dicarboxylic acids (B1) is 60 mol% or more with respect to the entire dicarboxylic acid component (B), and the high trans-form ratio makes the film reverse wavelength dispersibility. It is possible to achieve both thinning and heat resistance. The ratio of the trans compound in the resin may be 60 mol% or more, but the preferable range is 65 to 99 mol%, 70 to 95 mol%, 75 to 90 mol%, and 80 to 90 mol% in stages. 85 mol% is most preferred. If the ratio of the transformer body is too low, both inverse wavelength dispersibility and thinning cannot be achieved at the same time. In the present specification and claims, the trans-form ratio of alicyclic dicarboxylic acids (B1) can be measured by NMR, and in detail, it can be measured by the method described in Examples described later.

Examples of the alicyclic dicarboxylic acids include cycloalkane dicarboxylic acids, cross-linked cycloalkane dicarboxylic acids, cycloalkene dicarboxylic acids, and cross-linked cycloalkene dicarboxylic acids.

Examples of cycloalkandicarboxylic acids include cyclopentanedicarboxylic acids; cyclohexanedicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; cycloheptandicarboxylic acid; cyclooctanedicarboxylic acid. Examples thereof include C _4-12 cycloalkane-dicarboxylic acids such as, and ester-forming derivatives thereof.

_{Examples of the crosslinked cyclic cycloalkanedicarboxylic acids include (di or tri) cycloC 7-10} alkane-dicarboxylic acids such as decalindicarboxylic acid, norbornanedicarboxylic acid, adamantandicarboxylic acid, and tricyclodecanedicarboxylic acid, and ester-forming derivatives thereof. And so on.

Examples of cycloalkene dicarboxylic acids include cyclopentene dicarboxylic acids; cyclohexene dicarboxylic acids such as tetrahydrophthalic acid; C _5-10 cycloalkene-dicarboxylic acids such as cyclooctene dicarboxylic acids; and ester-forming derivatives thereof.

Examples of the crosslinked cyclic cycloalkenedicarboxylic acids include (di or tri) cycloC _7-10 alkene-dicarboxylic acids such as norbornene dicarboxylic acids, and ester-forming derivatives thereof.

These alicyclic dicarboxylic acids can be used alone or in combination of two or more. Of these, C _5-10 cycloalkane-dicarboxylic acids are preferable, and cyclohexanedicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid or ester-forming derivatives thereof. Is more preferable, and 1,4-cyclohexanedicarboxylic acid or an ester-forming derivative thereof is most preferable. The ester-forming derivative is preferably a _{C1-2 alkyl ester such as a methyl ester.}

The ratio of the alicyclic dicarboxylic acids (B1) may be 50 mol% or more in the dicarboxylic acid component (B) in the resin, and the preferable range is 80 mol% or more and 90 mol in the following steps. % Or more, 95 mol% or more, 99 mol% or more, most preferably 100 mol%.

[(B2) Aromatic dicarboxylic acids]
The dicarboxylic acid component (B) may contain aromatic dicarboxylic acids (B2) in addition to the alicyclic carboxylic acids (B1) in order to improve heat resistance.

Examples of aromatic dicarboxylic acids (B2) include arene dicarboxylic acids and dicarboxylic acids having a diaryl skeleton.

Examples of the arenedicarboxylic acid component include benzenedicarboxylic acids; alkylbenzenedicarboxylic acids; condensed polycyclic arenedicarboxylic acids, and polycyclic arenedicarboxylic acids such as ring-assembled arenedicarboxylic acids.

Examples of benzenedicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, and ester-forming derivatives thereof.

_{Examples of alkylbenzene dicarboxylic acids include C 1-4} alkyl-benzene dicarboxylic acids such as methyl terephthalic acid, 4-methyl isophthalic acid, and 5-methyl isophthalic acid, or ester-forming derivatives thereof.

Examples of the fused polycyclic allene dicarboxylic acid include condensed polycyclic C _10-18 allene-dicarboxylic acid such as naphthalenedicarboxylic acid, anthracene dicarboxylic acid and phenanthrene dicarboxylic acid, or an ester-forming derivative thereof. Examples of the naphthalenedicarboxylic acid include 1,2-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, and 2,6-. Naphthalenedicarboxylic acids having two carboxyl groups on different rings such as naphthalenedicarboxylic acids; naphthalenedicarboxylic acids having two carboxyl groups on the same ring such as 1,2-naphthalenedicarboxylic acids and 1,4-naphthalenedicarboxylic acids; Examples thereof include an ester-forming derivative of.

_{Examples of the ring-assembled arenedicarboxylic acids include biC 6-10} arene-dicarboxylic acids such as 2,2'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, and 4,4'-biphenyldicarboxylic acid, and ester formation thereof. Examples include sex derivatives.

Examples of dicarboxylic acids having a diaryl skeleton include diarylalkanedicarboxylic acids and diarylketone dicarboxylic acids.

Examples of the diarylalkanedicarboxylic acid include diC _{6-10arylC 1-6} alkane-dicarboxylic acid such as 4,4'-diphenylmethane dicarboxylic acid or an ester-forming derivative thereof.

Examples of the diarylketone dicarboxylic acid include a di (C _6-10 aryl) ketone-dicarboxylic acid such as 4,4'-diphenylketone dicarboxylic acid or an ester-forming derivative thereof.

These aromatic dicarboxylic acids (B2) can be used alone or in combination of two or more. Of these, benzenedicarboxylic acids, alkylbenzenedicarboxylic acids, and condensed polycyclic _C10-14 arene-dicarboxylic acids are preferable, and terephthalic acid or an ester-forming derivative thereof is particularly preferable. The ester-forming derivative is preferably a _{C1-2 alkyl ester such as a methyl ester.}

When the dicarboxylic acid component (B) contains aromatic dicarboxylic acids (B2), the molar ratio of the alicyclic dicarboxylic acid (B1) unit to the aromatic dicarboxylic acid (B2) unit is the former / latter = in the resin. It can be selected from a range of about 99/1 to 50/50, and the preferred range is 98/2 to 60/40, 97/3 to 70/30, 95/5 to 80/20 in a stepwise manner. 93/7 to 85/15 are the most preferable. If the proportion of the aromatic dicarboxylic acid (B2) is too large, it may be difficult to achieve both reverse wavelength dispersibility and thinning.

[(B3) Other dicarboxylic acids]
The dicarboxylic acid component (B) may contain other dicarboxylic acids (B3) in addition to the alicyclic carboxylic acids (B1).

Examples of other dicarboxylic acids (B3) include aliphatic dicarboxylic acids and dicarboxylic acids having a fluorene skeleton.

Aliphatic dicarboxylic acids can be roughly classified into saturated aliphatic dicarboxylic acids and unsaturated aliphatic dicarboxylic acids.

Examples of saturated aliphatic dicarboxylic acids include oxalic acid or an ester-forming derivative thereof, alkanedicarboxylic acids and the like. _{Examples of alkanedicarboxylic acids include C 1-18} alkane-dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decandicarboxylic acid, undecandicarboxylic acid and dodecanedicarboxylic acid. Examples thereof include an acid or an ester-forming derivative thereof.

_{Examples of unsaturated aliphatic dicarboxylic acids include C 2-10} alkene-dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, or ester-forming derivatives thereof.

Examples of dicarboxylic acids having a fluorene skeleton include 9,9-bis (carboxyalkyl) fluorenes, 9- (dicarboxyalkyl) fluorenes, 9,9-bis (carboxyaryl) fluorenes, dicarboxyfluorenes, 9, Examples thereof include 9-dialkyl-dicarboxyfluorenes.

Examples of 9,9-bis (carboxyalkyl) fluorenes include 9,9-bis (2-carboxyethyl) fluorene and 9,9-bis (2-carboxypropyl) fluorene and other 9,9-bis (carboxy C _{2). -6} alkyl) fluorene or an ester-forming derivative thereof can be mentioned.

_{Examples of 9- (dicarboxyalkyl) fluorenes include 9- (dicarboxyC 2-8} alkyl) such as 9- (1,2-dicarboxyethyl) fluorene and 9- (2,3-dicarboxypropyl) fluorene. Fluorene or an ester-forming derivative thereof and the like can be mentioned.

The 9,9-bis (carboxymethyl aryl) fluorenes, such as 9,9-bis (4-carboxyphenyl) fluorene such as 9,9-bis (carboxy _{C 6-10} aryl) fluorene or an ester-forming derivative Can be mentioned.

Examples of dicarboxyfluorenes include 2,7-dicarboxyfluorene or an ester-forming derivative thereof.

Examples of the 9,9-dialkyl-dicarboxyfluorene include 9,9-diC _1-10 alkyl-dicarboxyfluorene such as 2,7-dicarboxy-9,9-dimethylfluorene or an ester-forming derivative thereof. Can be mentioned.

These other dicarboxylic acids (B3) can be used alone or in combination of two or more. The ratio of the other dicarboxylic acids (B3) may be 50 mol% or less in the dicarboxylic acid component (B), preferably 10 mol% or less, more preferably 5 mol% or less, and most preferably 5 mol% or less in the resin. It is 1 mol% or less. If the proportion of other dicarboxylic acids (B3) is too large, it may be difficult to achieve both reverse wavelength dispersibility and thinning.

[Other thermoplastic resins]
The polymer for a retardation film of the present invention may be a polymer formed of the polyester resin alone, but in order to adjust the inverse wavelength dispersibility and improve heat resistance and retardation, the polymer may be combined with the polyester resin. It may be a polymer alloy with other thermoplastic resins. Examples of other thermoplastic resins include styrene resins, polycarbonate resins, polyamide resins, polyphenylene ether resins, and polyphenylene sulfide resins. These other thermoplastic resins can be used alone or in combination of two or more. Among these other thermoplastic resins, a polycarbonate resin is preferable from the viewpoint of optical properties and compatibility with a polyester resin. In particular, by combining a polyester resin and a polycarbonate resin, it is possible to produce a retardation film having both optical properties, heat resistance, and thin wall properties.

As the polycarbonate resin, a conventional polycarbonate, for example, an aromatic polycarbonate based on bi or bisphenols can be used.

Examples of biphenols include p, p'-biphenol and the like.

Bisphenols include bis (hydroxyphenyl) alkanes, bis (hydroxyaryl) cycloalkanes, bis (hydroxyaryl) ethers, bis (hydroxyaryl) ketones, bis (hydroxyphenyl) sulfones, and bis (hydroxyphenyl). ) Sulfoxides, bis (hydroxyphenyl) sulfides and the like can be mentioned.

Examples of bis (hydroxyphenyl) alkanes include bis (4-hydroxyphenyl) methane (bisphenol F), 1,1-bis (4-hydroxyphenyl) ethane (bisphenol AD), and 2,2-bis (4-hydroxyphenyl). ) Propane (bisphenol A), 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3 _{Examples thereof include bis (hydroxyaryl) C 1-6} alkanes such as -methylbutane and 2,2-bis (4-hydroxyxysilyl) propane.

_{Examples of bis (hydroxyaryl) cycloalkanes include bis (hydroxyaryl) C 4-10} cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclopentane and 1,1-bis (4-hydroxyphenyl) cyclohexane. Kind and so on.

Examples of bis (hydroxyaryl) ethers include bis (4-hydroxyphenyl) ethers.

Examples of bis (hydroxyaryl) ketones include 4,4'-dihydroxybenzophenone.

Examples of the bis (hydroxyphenyl) sulfone include bis (4-hydroxyphenyl) sulfone (bisphenol S).

Examples of the bis (hydroxyphenyl) sulfoxide include bis (4-hydroxyphenyl) sulfoxide.

Examples of bis (hydroxyphenyl) sulfides include bis (4-hydroxyphenyl) sulfide.

These bi or bisphenols _{may be C 2-4} alkylene oxide adducts. These bi or bisphenols can be used alone or in combination of two or more. Of these bi or bisphenols, bis (hydroxyaryl) C _1-6 alkanes such as bisphenol A are preferred.

The polycarbonate resin may be a polyester carbonate-based resin in which a dicarboxylic acid component (such as an aliphatic, alicyclic or aromatic dicarboxylic acid or an acid halide thereof) is copolymerized. These polycarbonate resins can be used alone or in combination of two or more. A preferred polycarbonate resin is _{a resin based on bis (hydroxyphenyl) C 1-6} alkanes, for example, a bisphenol A type polycarbonate resin.

The ratio of the other thermoplastic resin resin can be appropriately selected according to the desired optical characteristics and heat resistance, and is, for example, 0.1 to 300 parts by mass, preferably 0.3 to 200 parts by mass with respect to 100 parts by mass of the polyester resin. Parts, more preferably 0.5 to 100 parts by mass, and most preferably 1 to 50 parts by mass.

The ratio of the polycarbonate resin can be appropriately selected according to the desired optical characteristics and heat resistance, and can be selected from the range of about 0.1 to 100 parts by mass with respect to 100 parts by mass of the polyester resin, for example, 0.5 to 30 parts by mass. It is preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, and most preferably 2.5 to 5 parts by mass.

[Polymer for retardation film]
The polymer for a retardation film of the present invention may contain a polyester resin obtained by reacting the diol (A) with the dicarboxylic acids (B) as a polymerization component, and the polyester resin alone or the polyester thus obtained may be contained. A polymer alloy of a resin and another thermoplastic resin, particularly a polymer alloy of a polyester resin and a polycarbonate resin.

The polyester resin represented by the above formula (1) contained in the retardation film polymer of the present invention can be obtained by a conventional method, for example, a melt polymerization method such as a transesterification method or a direct polymerization method; a solution polymerization method; an interfacial polymerization method. It can be prepared by polymerizing with or the like. Of these methods, the melt polymerization method is preferable. The reaction may be carried out in the presence or absence of a solvent, depending on the polymerization method.

The usage ratio (or charging ratio) of the diol (A) and the dicarboxylic acid component (B) is usually the former / the latter (molar ratio) = 1 / 1.2 to 1 / 0.8, preferably 1/1. It is 1 to 1 / 0.9. In the reaction, the amount (ratio) of each diol (A) and dicarboxylic acid component (B) used may be the same as the ratio of each diol unit and dicarboxylic acid unit in the resin, including a preferable embodiment. Well, if necessary, each component may be used in excess to react. For example, the diol (A2) such as ethylene glycol that can be distilled from the reaction system may be used in excess of the ratio (or introduction ratio) introduced into the polyester resin.

The reaction may be carried out in the presence of a catalyst. As the catalyst, a metal catalyst or the like, which is a conventional esterification catalyst, can be used. As metal catalysts, alkali metals such as sodium; alkaline earth metals such as magnesium, calcium and barium; transition metals such as manganese, zinc, cadmium, lead, cobalt and titanium; periodic table group 13 metals such as aluminum; germanium 14th Group Metals of the Periodic Table; Metal compounds containing 15th Group Metals of the Periodic Table such as Antimon are used. The metal compound may be an alkoxide; an organic acid salt such as an acetate or a propionate; an inorganic acid salt such as a borate or a carbonate; a metal oxide or the like, or a hydrate thereof. ..

Typical metal compounds include germanium compounds such as germanium dioxide, germanium hydroxide, germanium oxalate, germanium tetraethoxydo, and germanium-n-butoxide; antimony compounds such as antimony trioxide, antimonate acetate, and antimonate ethylene lycolate; Titanium compounds such as tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, titanium oxalate, potassium titanium oxalate; manganese compounds such as manganese acetate / tetrahydrate; calcium acetate / monohydrate Calcium compounds such as.

These catalysts can be used alone or in combination of two or more. When a plurality of catalysts are used, each catalyst can be added according to the progress of the reaction. Of these catalysts, manganese acetate tetrahydrate, calcium acetate monohydrate, and germanium dioxide 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 ^-4 mol, based on 1 mol of the dicarboxylic acid component (B). Is.

If necessary, the reaction may be carried out in the presence of a stabilizer such as a phosphorus compound such as trimethyl phosphate, triethyl phosphate, triphenyl phosphate, hydride, trimethyl phosphite, or triethyl phosphate. 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 × 10 ^{-4, relative to 1 mol of the dicarboxylic acid component (B).} It is a mole.

The reaction may be carried out in air or usually in an inert gas atmosphere. Examples of the inert gas include nitrogen; a rare gas such as helium and argon. The reaction can also be carried out under a reduced pressure of about 1 × 10 ² to 1 × 10 ^{4 Pa.} The reaction temperature can be selected according to the polymerization method, and the reaction temperature in the melt polymerization method is, for example, 150 to 300 ° C., preferably 180 to 290 ° C., and more preferably 200 to 280 ° C.

When the polymer for retardation film of the present invention is a polymer alloy, the polycarbonate resin contained in the polymer alloy is produced by a conventional method, for example, a phosgene method (solvent method) or a transesterification method (melting method). Can be used.

The glass transition temperature Tg of the polymer for retardation film of the present invention can be selected from the range of about 50 to 200 ° C., and the preferred range is 70 to 180 ° C., 80 to 160 ° C., 100 to 150 ° C. in the following steps. The temperature is 110 to 145 ° C, 115 to 142 ° C, 120 to 140 ° C, and most preferably 130 to 135 ° C. When the polymer is a polymer alloy, the polymer alloy may have one glass transition temperature Tg because the polymer alloy is completely compatible with each other. If the glass transition temperature Tg is too low, the heat resistance is lowered, and the resin may be deformed or discolored (or colored) during use, and if the Tg is too high, the moldability may be lowered. In the present specification and claims, the glass transition temperature Tg can be measured by the method described in the case described later.

The polymer for a retardation film of the present invention is characterized by having a large molecular weight (weight average molecular weight Mw, etc.). The weight average molecular weight Mw of the polymer for retardation film of the present invention can be measured by gel permeation chromatography (GPC) or the like, and can be selected from the range of, for example, 30,000 to 200,000 in terms of polystyrene. It is 40,000 to 150,000, 50,000 to 100,000, 55,000 to 90000, and most preferably 60000 to 80,000. When the polymer is a polymer alloy, the weight average molecular weight Mw is, for example, 30,000 to 100,000, preferably 40,000 to 80,000, and more preferably 50,000 to 60,000. The polymer has a large molecular weight and degree of polymerization (long molecular chain), and has excellent mechanical properties (break elongation, flexibility, etc.). In the present specification and claims, the weight average molecular weight Mw can be measured by gel permeation chromatography (GPC) in terms of polystyrene.

The refractive index of the polymer for retardation film of the present invention can be selected from a range of about 1.50 to 1.65 at a temperature of 20 ° C. and a wavelength of 589 nm. It is .64, 1.54 to 1.63, 1.56 to 1.62, and most preferably 1.58 to 1.618.

The Abbe number of the retardation film polymer of the present invention is, for example, 22 to 32, preferably 23 to 31, and more preferably 24 to 30 at a temperature of 20 ° C.

The deflection temperature under load (ISO75-1, load 1.80 MPa) of the polycarbonate resin contained in the polymer alloy can be selected from the range of about 100 to 200 ° C., for example, about 100 to 150 ° C., preferably 110 to 140 ° C., more preferably. Is 120 to 135 ° C, most preferably 125 to 130 ° C.

The melt mass flow rate (ISO1133, 300 ° C., 1.2 kgf) of the polycarbonate resin can be selected from the range of about 1 to 30 g / 10 minutes, for example, 3 to 20 g / 10 minutes, preferably 5 to 15 g / 10 minutes, more preferably. It is 7 to 13 g / 10 minutes, most preferably 8 to 12 g / 10 minutes.

The glass transition temperature Tg of the polycarbonate resin is, for example, 50 to 200 ° C., preferably 100 to 180 ° C., more preferably 120 to 160 ° C., and most preferably 150 to 155 ° C.

The weight average molecular weight Mw of the polycarbonate resin is, for example, 1000 to 100,000, preferably 30,000 to 80,000, and more preferably about 50,000 to 70,000.

The birefringence of the polymer for a retardation film may be evaluated by the birefringence (3x birefringence) of a stretched film obtained by stretching a film formed of polyester alone or a polymer alloy at a stretching magnification of 3 times. Birefringence (3x birefringence) is represented by the absolute value of the difference between the refractive index in the stretching direction and the refractive index in the direction perpendicular to this direction in the film plane. Therefore, the triple birefringence of the stretched film prepared under stretching conditions of stretching temperature (glass transition temperature Tg + 10) ° C. and stretching speed of 25 mm / min is, for example, 0 × 10 ^-4 to +50 at a measurement temperature of 20 ° C. and a wavelength of 600 nm. It is × 10 ^-4 , preferably 0 × 10 ^{-4 to +25} × 10 -4, and more preferably 0 × 10 ^-4 to +20 × 10 ^-4 .

The retardation film polymer of the present invention may contain various conventional additives as long as the effects of the present invention are not impaired. Conventional additives include polymerization initiators; plasticizers such as esters, phthalic compounds, epoxy compounds, and sulfonamides; flame retardants such as inorganic flame retardants, organic flame retardants, and colloidal flame retardants; Stabilizers such as stabilizers and antioxidants; Antistatic agents; Oxide-based inorganic fillers, non-oxide inorganic fillers, fillers such as metal powders; Foaming agents; Antifoaming agents; Lubricants; Natural waxes, Mold release agents such as synthetic waxes, linear fatty acids or metal salts thereof, acid amides, etc .; slippery imparting agents can be mentioned. Examples of the slipper-imparting agent include inorganic particles such as silica, titanium oxide, calcium carbonate, clay, mica, and kaolin; and organic particles such as (meth) acrylic resin and styrene resin (crosslinked polystyrene resin, etc.). .. These additives may be used alone or in combination of two or more.

The ratio of these conventional additives is, for example, 30 parts by mass or less, preferably 0.1 to 20 parts by mass, and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the retardation film polymer.

These additives may be added by a conventional method, for example, a method of melt-kneading with a retardation film polymer using a single-screw or twin-screw extruder (preferably a twin-screw extruder from the viewpoint of dispersibility). Good. The additive may be added in advance before the film-forming of the retardation film polymer, but for example, in order to supply the retardation film polymer to the film-forming apparatus when melt-forming the retardation film polymer. It is preferable to melt-knead using the extruder of the above because it is economically advantageous.

[The retardation film and its manufacturing method]
The retardation film of the present invention is a film formed of the above-mentioned retardation film polymer and stretched. The in-plane retardation (front retardation) R of the retardation film of the present invention can be calculated by the following formula.

R = (nx-ny) x d
(In the formula, nx indicates the refractive index in the slow phase axis direction of the film, ny the refractive index in the phase advance axis direction, and d indicates the thickness of the film).

Assuming that the in-plane phase difference at the wavelength λ nm is Rλ, the in-plane phase difference R550 at a temperature of 20 ° C. and a wavelength of 550 nm can be selected from a range of about 100 to 160 nm at a thickness of 50 μm. It is ~ 155 nm, 110-150 nm, 115-148 nm, 120-145 nm, 130-142 nm, and most preferably 135-140 nm. In the present specification and claims, the in-plane retardation at a thickness of 50 μm is the front phase difference of a film having a thickness of 50 μm, and is a value obtained by converting the in-plane retardation of a film having a thickness of d into a thickness of 50 μm. ..

The retardation film of the present invention has an inverse wavelength dispersion characteristic. Therefore, R450 / R550, which is the ratio of the in-plane retardation R450 to the in-plane retardation R550 at a wavelength of 450 nm, is 0.8 or more and less than 1, preferably 0.802 to 0.95, and more preferably 0. It is 805 to 0.92, 0.808 to 0.9, 0.81 to 0.88, 0.812 to 0.87, and most preferably 0.815 to 0.86. The ideal wideband 1/4 wave plate has a R450 / R550 of about 0.818.

The retardation film of the present invention can be thinned even though it exhibits anti-wavelength dispersibility. The average thickness of the retardation film of the present invention may be 100 μm or less, preferably 60 μm or less, more preferably 50 μm or less, more preferably 40 μm or less, and most preferably 35 μm or less. The average thickness of the retardation film is, for example, 10 to 60 μm, preferably 20 to 50 μm, more preferably 25 to 40 μm, more preferably 28 to 37 μm, and most preferably 30 to 35 μm. If the average thickness is too small, the take-up property at the time of film formation may be lowered, and stable take-up may not be possible, and breakage may occur in the stretching step. Further, since the phase difference is proportional to the film thickness, the occurrence of the phase difference may decrease. On the other hand, if the average thickness is too large, there is a possibility that the thinness requirement of the circularly polarizing plate cannot be met, and warpage occurs during drying in the bonding process with the polarizing element, and the optical properties of the finally obtained polarizer. There is also a risk of inhibiting.

The retardation film of the present invention is obtained through a film-forming step of obtaining a film by extrusion molding or solution cast molding, and a stretching step of stretching the film obtained in the film-forming step.

In the film forming step, as a method for forming a film, for example, it can be prepared by a casting method (solution casting method), an extrusion method (a melt extrusion method such as an inflation method or a T-die method), a calendar method, or the like. An extrusion molding method such as a melt extrusion method using a T-die or a solution cast molding method is preferable because a long resin film can be easily produced and continuous production can be easily performed through a stretching step such as uniaxial stretching. , Extrusion molding is particularly preferred. As the melt extrusion method, molding conditions can be adjusted according to the glass transition temperature and melting point of the retardation film polymer, and molding can be performed by a conventional method.

The average thickness of the film obtained in the film forming step is, for example, 30 to 300 μm, preferably 50 to 200 μm, more preferably 60 to 150 μm, and most preferably 80 to 120 μm.

In the stretching step, the stretching method may be either a dry stretching method of stretching in air or a wet stretching method of stretching in water, or both methods may be used in combination. The stretching may be uniaxial stretching, biaxial stretching, or diagonal stretching.

The stretching temperature may be a temperature equal to or higher than the glass transition temperature (Tg) of the retardation film polymer constituting the film and lower than the melting point, but the preferable range is Tg to Tg + 30 ° C. and Tg + 1 in a stepwise manner. ~ Tg + 20 ° C., Tg + 2 to Tg + 10 ° C., Tg + 3 to Tg + 8 ° C., most preferably Tg + 4 to Tg + 7 ° C. If the stretching temperature is too high, the orientation relaxation becomes strong and a sufficient phase difference may not be developed. On the contrary, if the stretching temperature is too low, the phase difference is likely to occur, but there is a risk of breakage.

The draw ratio can be selected from, for example, a range of about 2 to 5 times, and the preferred range is 2.5 to 5 times, 2.8 to 5 times, and 3 to 4.5 times in a stepwise manner, which is most preferable. Is 3.5 to 4 times. If the draw ratio is too low, a sufficient phase difference may not be exhibited, and conversely, if it is too high, there is a risk of breakage.

[Circular polarizing plate and image display device]
The retardation film of the present invention can form a circular polarizing plate as a 1/4 wavelength retardation film by directly bonding it to a polarizing element (polarizing plate). As the polarizer, a polyvinyl alcohol (PVA) film is usually used.

The retardation film obtained by the above method may be subjected to corona treatment, plasma treatment, and surface modification treatment with a strong base aqueous solution such as sodium hydroxide or potassium hydroxide in order to improve the adhesion to the polarizer. .. Further, a thin film such as a primer layer may be formed on the surface of the retardation film. These surface modification treatments and thin film formation may be carried out after undergoing a film forming step or may be carried out after undergoing a diagonal stretching step.

The circularly polarizing plate of the present invention may be a laminate of the retardation film and the polarizer, but usually, a transparent protective film is laminated on the opposite surface to the surface on which the retardation film of the polarizer is laminated. There is. The transparent protective film may be a material that has high adhesion to a polarizer such as a PVA film and is optically transparent, but has high transparency, mechanical strength, and low optical anisotropy. Therefore, a cellulose ester-based film such as a triacetyl cellulose (TAC) film and a cellulose acetate propionate film, a modified acrylic resin-based film, an ultra-high birefractive polyethylene terephthalate resin-based film, a cycloolefin-based film, and the like are widely used.

An adhesive may be interposed between the layers of the circularly polarizing plate of the present invention. As the adhesive, a water-based adhesive is generally used. Examples of the water-based adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex adhesives, water-based polyurethane adhesives, and water-based polyester adhesives. Of these, polyvinyl alcohol-based adhesives are preferable.

The image display device of the present invention includes the obtained circularly polarizing plate as an optical film. Examples of the image display device of the present invention include a liquid crystal display device and an organic EL display.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The evaluation method is shown below.

[NMR]
^{1 1} H NMR spectrum was measured using "AVANCE III HD (300 MHz)" manufactured by Bruker BIOSPIN.

[Glass transition temperature (Tg)]
Using a differential scanning calorimeter (“DSC 6220” manufactured by Seiko Instruments Inc.), a sample was placed in an aluminum pan, and Tg was measured in the range of 30 to 220 ° C.

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

[Average thickness]
It was measured with a thickness gauge (“Micrometer” manufactured by Mitutoyo Co., Ltd.). The average thickness was measured at three points at equal intervals between the chucks in the longitudinal direction of the film, and the average value was calculated.

[Phase difference]
The in-plane retardation R450 and R550 of the inverse wavelength dispersive film and the wavelength dispersion characteristic R450 / R550 of the phase difference are measured at wavelengths of 450 nm and 550 nm using a retardation measuring device (“RETS-100” manufactured by Otsuka Electronics Co., Ltd.). It was measured.

Example 1
(Synthesis of copolymerized polyester resin)
9,9-Bis [4- (2-hydroxyethoxy) phenyl] fluorene (manufactured by Osaka Gas Chemical Co., Ltd., hereinafter referred to as "BPEF") 0.6 mol, ethylene glycol (hereinafter referred to as "EG") 1. 0 mol, 1.0 mol of dimethyl 1,4-cyclohexanedicarboxylate (trans ratio 98 mol%, hereinafter referred to as "CHDA-M"), manganese acetate tetrahydrate 2 × 10 ^-4 mol as esterification catalyst ^{8 × 10 -4} mol of calcium acetate / monohydrate was added and gradually heated and melted with stirring, and after raising the temperature to 230 ° C., 14 × 10 ^-4 mol of trimethyl phosphate and 20 × 10 ^-4 mol of germanium oxide Was added, and ethylene glycol was removed while gradually raising the temperature and reducing the pressure until the temperature reached 0.13 KPa at 270 ° C. After reaching the predetermined stirring torque, the contents were taken out from the reactor to obtain polyester resin pellets. When the obtained pellets were analyzed by NMR, 59 mol% of the diol component introduced into the polyester resin was derived from BPEF, and 41 mol% was derived from EG. 83 mol% of the dicarboxylic acid component introduced into the polyester resin was derived from the trans form of CHDA-M, and 17 mol% was derived from the cis form of CHDA-M. The glass transition temperature Tg of the obtained polyester resin was 120 ° C., and Mw was 61400.

(Reverse wavelength dispersive film formation)
The obtained resin pellets are supplied to a twin-screw extruder (screw diameter 40 mm, L / D = 32) equipped with a T-die, and a film having an effective width of 200 mm is extruded at a cylinder temperature of 260 ° C. and wound on a roll. It was. The thickness was 150 μm.

(Uniaxial stretching treatment)
A uniaxially stretched film was produced under a stretching condition of a temperature of 123 ° C. and a magnification of 3.5 times using a stretching device (“Film Biaxial Stretching Machine IMC-1A97”) manufactured by Imoto Seisakusho Co., Ltd. The average thickness and phase difference were measured.

Examples 2-5
A copolymerized polyester was produced in the same manner as in Example 1 except that the charging ratio was changed, and after measuring Tg and Mw, a reverse wavelength dispersion film was produced in the same manner as in Example 1 except that the stretching conditions were changed. , Average thickness and phase difference were measured.

Examples 6-8
A copolymerized polyester was produced in the same manner as in Example 1 except that dimethyl terephthalate (hereinafter referred to as “DMT”) was added as a monomer and the charging ratio was changed, and after measuring Tg and Mw, the stretching conditions were changed. A reverse wavelength dispersion film was produced in the same manner as in Example 1 except for the above, and the average thickness and the phase difference were measured.

Examples 9-12
Except for adding 1 to 4 parts by mass of polycarbonate (“Iupilon E-2000” manufactured by Mitsubishi Engineering Plastics Co., Ltd., Tg152 ° C., Mw65000, hereinafter referred to as “PC”) to 100 parts by mass of the obtained resin pellets. A film having an effective width of 200 mm (thickness 60 to 100 μm) was extruded in the same manner as in Example 4 and wound on a roll, and then a reverse wavelength dispersion film was produced in the same manner as in Example 4 except that the stretching conditions were changed. , Average thickness and phase difference were measured. In Table 1, the glass transition temperature Tg and the weight average molecular weight Mw of Examples 9 to 12 are both Tg and Mw of the polymer alloy molded into the film.

Comparative Examples 1-2
A copolymerized polyester was produced in the same manner as in Example 1 except that 1,4-cyclohexanedicarboxylic acid (trans ratio 30 mol%, hereinafter referred to as “CHDA”) was used instead of CHDA-M to change the charging ratio. Then, after measuring Tg and Mw, a reverse wavelength dispersion film was produced in the same manner as in Example 1 except that the stretching conditions were changed, and the average thickness and the phase difference were measured.

Table 1 shows the evaluation results of Examples and Comparative Examples.

As is clear from the results in Table 1, in the examples, the heat resistance is high, the wall thickness is thin, and the reverse wavelength dispersion is exhibited, whereas in the comparative example, the heat resistance, the wall thinning, and the reverse wavelength dispersion are exhibited. Gender cannot be satisfied at the same time. In particular, Examples 3 to 4 and 11 to 12 are preferable in the required applications, respectively, and in Example 3, high reverse wavelength dispersibility is realized in a thin wall. Further, in Example 4, heat resistance and reverse wavelength dispersibility are high. Further, in Examples 11 and 12, high heat resistance is realized in a thin wall.

The polymer for a retardation film of the present invention can be adjusted so that the retardation has a negative wavelength dispersion characteristic over a wide band of visible light by stretching. Therefore, it can be suitably used as a 1/4 wave plate [for example, a 1/4 wave plate that functions over a wide band of visible light (such as the entire visible light range)]. Further, by laminating a retardation film formed of the polymer for retardation film of the present invention with a polarizing plate, a circular polarizing plate having excellent antireflection and wide bandwidth can be produced. The circularly polarizing plate is suitably used for an image display device (for example, a reflective liquid crystal display device, a transflective liquid crystal display device, an organic EL display device, etc.).

Claims (12)

It contains a polyester resin containing a diol (A) containing full orange all (A1) represented by the following formula (1) and a dicarboxylic acid component (B) containing an alicyclic dicarboxylic acid (B1) as a polymerization component. A polymer for a retardation film in which the trans-form ratio of the alicyclic dicarboxylic acids (B1) is 60 mol% or more of the total dicarboxylic acid component (B).

(In the formula, Z ¹ and Z ² show the same or different aromatic hydrocarbon rings, R ¹ and R ² show the same or different substituents, and A ¹ and A ² show the same or different. Indicates an alkylene group, R ³ indicates a substituent, m1 and m2 indicate the same or different integers of 0 or more, n1 and n2 indicate the same or different integers of 0 or 1 or more, and k Indicates an integer from 0 to 8) The polymer for a retardation film according to claim 1, wherein the diol (A) further contains an aliphatic diol (A2). The polymer for a retardation film according to claim 2, wherein the molar ratio of the full orange all (A1) to the aliphatic diol (A2) is the former / the latter = 99/1 to 10/90. The polymer for a retardation film according to any one of claims 1 to 3, wherein the dicarboxylic acid component (B) further contains an aromatic dicarboxylic acid (B2). The polymer for a retardation film according to any one of claims 1 to 4, which is a polymer alloy of the polyester resin and the polycarbonate resin. A retardation film obtained by stretching and molding the polymer for a retardation film according to any one of claims 1 to 5. The retardation film according to claim 6, wherein the average thickness is 100 μm or less. A method for producing a retardation film, which comprises a film forming step of obtaining a film by extrusion molding or solution casting molding, and a stretching step of stretching the film obtained in the film forming step. The method for producing a retardation film according to claim 8, wherein the stretching ratio of the stretching step is 2 to 5 times. A circularly polarizing plate in which the retardation film according to claim 6 or 7 and a polarizer are laminated. An image display device including the circularly polarizing plate according to claim 10. The image display device according to claim 11, which is an organic EL display.