TWI809079B - Polymer for retardation film, retardation film and method for producing the same and use thereof - Google Patents

Abstract

The present invention produces a retardation film comprising a polyester resin, which contains a diol (A) containing a fluorenediol (A1) represented by the following formula (1), and a dicarboxylic acid component (B) containing an alicyclic dicarboxylic acid (B1) having a trans isomer ratio of 60 mol% or more as polymerization components.

(In the formula, Z¹ and Z² represent identical or different aromatic hydrocarbon rings, R¹ and R² represent identical or different substituents, A¹ and A² represent identical or different alkylene groups, R³ represents a substituent, m1 and m2 represent identical or different integers of 0 or more, n1 and n2 represent identical or different integers of 0 or 1 or more, k represents an integer of 0 to 8)

The obtained retardation film can achieve a balance between the reverse wavelength dispersion characteristic and the thinning of film.

Description

Polymer for retardation film, retardation film, production method and use thereof

The present invention relates to polymers containing polyester resins that can be used in retardation films, retardation films formed from these polymers for retardation films, and their production methods and uses. The above retardation films are used in Circular polarizer with anti-reflection function in broadband.

The circular polarizing plate is a 1/4 wavelength plate with a phase difference of 1/4 wavelength and a polarizing plate (linear polarizing plate), so that the absorption axis of the polarizing plate is relative to the slow axis of the 1/4 wavelength plate. 45°crossing angle is bonded and formed, which is used in image display devices such as reflective liquid crystal display devices, semi-transmissive liquid crystal display devices, touch displays, organic electroluminescent (EL) displays, etc., in order to control Display images in a polarized state, or use it to absorb reflected light to ensure visibility. In particular, since organic EL displays are installed in smartphones in recent years, it is necessary to prevent reflection of external light, so the importance of circularly polarizing plates has increased.

Since the general 1/4 wavelength plate functions for light of a specific wavelength, coloring due to light (for example, blue) outside the wavelength region to be used may occur, or black display may become insufficient, resulting in Recognizability is easily reduced. Therefore, there is a need for a retardation film having an inverse wavelength dispersion characteristic in which the retardation becomes almost 1/4 wavelength in a wide band of visible light. Furthermore, in recent years, smartphones have been required to be thinner. However, it is difficult to cope with the further thinning of the positive wavelength dispersive film that requires the use of two 1/4 wavelength retardation films. Wavelength dispersive film.

Generally, polymers show positive wavelength dispersion characteristics, in which the retardation becomes smaller as the wavelength is longer. However, for polymers that show inverse wavelength dispersion characteristics, we have developed a film of copolymerized polycarbonate, etc., and adopted it. In a circular polarizing plate, the copolymerized polycarbonate has: the aromatic ring of the main chain and the aromatic ring of the side chain are perpendicular to the structural unit (cardo (Cardo) structure), and alicyclic hydrocarbons, cyclic ethers (oxygen-containing heterocyclic) structural unit.

In Japanese Unexamined Patent Application Publication No. 2010-134232 (Patent Document 1), a film composed of a polycarbonate copolymer having a bisphenylene skeleton and a cyclic ether skeleton is disclosed, and has a wavelength of 450nm, 550nm and 600nm. The in-plane retardation values R450, R550 and R600 are optical films of 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 times.

In addition, JP-A-2012-31369 (Patent Document 2) discloses that the phase difference R450 measured at a wavelength of 450 nm is formed with a polycarbonate resin containing a bisphenylene skeleton and a cyclic ether skeleton. A transparent film whose ratio to R550 measured at a wavelength of 550 nm is 0.5≦R450/R550≦1.0. In 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.

Furthermore, in Japanese Unexamined Patent Publication No. 2015-212368 (Patent Document 3), a transparent film containing a polycondensation-based resin having a repeating structural unit including a bisphenylene skeleton and a cyclic ether skeleton is disclosed. In addition, the ratio of the retardation R450 at a wavelength of 450 nm to the retardation R550 at a wavelength of 550 nm is 0.75≦R450/R550≦0.93. In the examples of this document, a retardation film is produced by uniaxially stretching a hot-pressed sheet or an extruded film at a stretching ratio of 1.5 to 2 times.

We have also developed a film of copolymerized polyester. In Japanese Patent Application Laid-Open No. 2015-200887 (Patent Document 4), it is disclosed that it is composed of a polyester copolymer having a bisphenylene skeleton and an alicyclic skeleton. The in-plane retardation values R450, R550 and R600 of wavelengths 450nm, 550nm and 600nm are optical films of R450<R550<R600. In Examples of this document, an optical film is manufactured by uniaxially stretching an extruded or cast film at a stretching ratio of 2 to 4 times.

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2010-134232

[Patent Document 2] Japanese Unexamined Patent Publication No. 2012-31369

[Patent Document 3] Japanese Patent Laid-Open No. 2015-212368

[Patent Document 4] Japanese Patent Laid-Open No. 2015-200887

In recent years, organic electroluminescent (EL) displays are expected to be flexible and foldable displays for applications such as smartphones or tablet computers. In such applications, from the viewpoint of improving bendability and preventing warpage, it is necessary to reduce the overall thickness, and circularly polarizing plates are also required to be thinner.

However, in the above-mentioned retardation film, regarding the requirement for further thinning of the circular polarizing plate, since the retardation of the 1/4 wavelength retardation film is proportional to the film thickness, there is a trade-off relationship between film thickness and retardation , so it is difficult to have both. In particular, the elongation of the resin containing the fennel skeleton is particularly difficult to control because the fennel skeleton is bulky and rigid.

Therefore, an object of the present invention is to provide a polymer capable of preparing a retardation film having both inverse wavelength dispersion characteristics and film thinning, a retardation film formed using the polymer, and a method for its production and use.

Another object of the present invention is to provide a polymer capable of preparing a retardation film with high heat resistance, a retardation film formed from the polymer, and its manufacturing method and use.

As a result of intensive research by the present inventors in order to achieve the aforementioned object, it was found that by using an alicyclic dicarboxylic acid containing a specific stilbene diol as a diol component and having a high trans-isomer ratio as a dicarboxylic acid component, The retardation film can be modulated by the polymer of the polyester resin, which can have both reverse wavelength dispersion characteristics and film thinning, thus completing the present invention.

That is, the polymer for retardation films of the present invention includes a polyester resin containing: a diol (A) including a fluorenediol (fluorenediol) (A1) represented by the following formula (1), and A dicarboxylic acid component (B) comprising alicyclic dicarboxylic acids (B1) as a polymerization component, wherein the trans isomer ratio of the alicyclic dicarboxylic acids (B1) is equal to that of the dicarboxylic acid component (B) More than 60 mol% of the whole.

(In the formula, Z ¹ and Z ² represent the same or different aromatic hydrocarbon rings, R ¹ and R ² represent the same or different substituents, A ¹ and A ² represent the same or different alkylene groups, R ³ represents substituted base, m1 and m2 represent the same or different integers of 0 or more, n1 and n2 represent the same or different integers of 0 or more, and k represents an integer of 0 to 8).

The aforementioned diol (A) may further include aliphatic diol (A2). The molar ratio of the aforementioned stilbene diol (A1) to the aforementioned aliphatic diol (A2) may be the former/the latter=99/1 to 10/90. The aforementioned dicarboxylic acid component (B) may further contain aromatic dicarboxylic acids (B2). The aforementioned polymer may be a polymer alloy of the aforementioned polyester resin and polycarbonate resin. The aforementioned 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 the aforementioned retardation film polymer. The average thickness of the retardation film may be 100 μm or less.

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

The present invention also includes a circular polarizing plate obtained by laminating the aforementioned retardation film and polarizing film. In addition, the present invention also includes an image display device including the aforementioned circular polarizing plate. The image display device may be an organic EL display.

Furthermore, in this specification and the scope of patent claims, the so-called "dicarboxylic acid components" and "dicarboxylic acids" refer to dicarboxylic acid esters such as dicarboxylic acid C _1-3 alkyl esters in addition to dicarboxylic acids. , dicarboxylic acid halides, dicarboxylic acid anhydrides and other ester-forming derivatives. Furthermore, the "ester-forming derivative" may be a monoester (half-ester) or a diester.

Moreover, in the scope of this specification and patent claims, the number of carbon atoms of a substituent is represented by C ₁ , C ₆ , C ₁₀ , etc. For example, "C ₁ alkyl" refers to an alkyl group with 1 carbon number, and "C _6-10 aryl group" refers to an aryl group with 6 to 10 carbon atoms.

Moreover, in the scope of this specification and patent claims, the so-called "polymer alloy" refers to a mixture (or mixture) of a plurality of polymers (or polymers, resins) that are not covalently bonded and mixed, and the resin component is In the state of complete miscibility, or in the state of stable microphase separation.

In addition, in the scope of this specification and patent claims, the in-plane retardation measured in a specific wavelength region is represented by R450, R550, and the like. That is, the in-plane retardation measured at a wavelength of 450 nm means "R450", and the in-plane retardation measured at a wavelength of 550 nm means "R550".

In the present invention, since the retardation film is prepared with a polymer comprising a polyester resin comprising an alicyclic diol having a specific stilbene diol as a diol and comprising a high trans isomer ratio Carboxylic acid is a dicarboxylic acid component, so it can achieve both reverse wavelength dispersion characteristics and film thinning. Furthermore, the heat resistance of a retardation film can be improved.

The polymer for the phase difference film of the present invention contains a polyester resin, wherein the polyester resin contains: a diol (A) containing stilbene diol (A1) represented by the following formula (1) and a diol (A) containing alicyclic diol (A1) The dicarboxylic acid component (B) of carboxylic acids (B1) is used as a polymerization component.

[(A1) fenneldiol]

The diol (A) includes the stilbene diol (A1) represented by the aforementioned formula (1). In the aforementioned formula (1), examples of the aromatic hydrocarbon rings (aromatic hydrocarbon rings) represented by ^Z1 and ^Z2 include, for example, monocyclic aromatic hydrocarbon rings (monocyclic aromatic hydrocarbon rings) such as benzene rings, polycyclic aromatic hydrocarbon rings, polycyclic aromatic hydrocarbon rings, etc. Aromatic hydrocarbon ring (polycyclic aromatic hydrocarbon ring), etc. Examples of the polycyclic aromatic hydrocarbon ring include condensed polycyclic aromatic hydrocarbon rings (condensed polycyclic aromatic hydrocarbon rings), aggregated aromatic hydrocarbon rings (aggregated aromatic hydrocarbon rings), and the like.

Examples of the condensed polycyclic aromatic hydrocarbon ring include condensed bicyclic to tetracyclic aromatic hydrocarbon rings such as condensed bicyclic aromatic hydrocarbon rings and condensed tricyclic aromatic hydrocarbon rings. Examples of the condensed bicyclic aromatic hydrocarbon ring include condensed bicyclic C _10-16 aromatic hydrocarbon rings such as naphthalene rings. Examples of the condensed tricyclic aromatic hydrocarbon ring include anthracene ring, phenanthrene ring and the like.

Examples of the agglomerated aromatic hydrocarbon ring include bisaromatic hydrocarbon rings such as bis C _6-12 aromatic hydrocarbon rings, triaromatic hydrocarbon rings such as tri C _6-12 aromatic hydrocarbon rings, and the like. Examples of the bis C _6-12 aromatic hydrocarbon ring include biphenyl ring; binaphthyl ring; phenylnaphthalene ring such as 1-phenylnaphthalene ring and 2-phenylnaphthalene ring, and the like. Examples of the three _C6-12 aromatic hydrocarbon rings include triphenylene rings and the like.

Among these aromatic hydrocarbon rings, C _6-12 aromatic hydrocarbon rings such as benzene ring, naphthalene ring, and biphenyl ring are preferred, and C _6-10 aromatic hydrocarbon rings such as benzene ring are particularly preferred.

In the aforementioned formula (1), examples of the substituent represented by ^R3 include hydrocarbon groups such as alkyl groups and aryl groups, cyano groups, halogen atoms, and the like. Examples of the alkyl group include linear or branched C _1-6 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl. Examples of the aryl group include C _6-10 aryl groups such as phenyl and the like. As the halogen atom, for example, a fluorine atom, a chlorine atom, a bromine atom or the like. Among these substituents, alkyl groups, cyano groups, and halogen atoms are preferred, and linear or branched C _1-4 alkyl groups are particularly preferred. Furthermore, among linear or branched C _1-4 alkyl groups, C _1-3 alkyl groups are preferred, and C _1-2 alkyl groups such as methyl are particularly preferred.

The substitution number k of R ³ is an integer of 0 to 8, and its preferred range is an integer of 0 to 6, an integer of 0 to 4, 0 to 2, and the most preferable range is 0. Furthermore, when k is 2 or more, the types of each R ³ may be the same or different from each other. In addition, when k is 2 or more, the types of R ³ substituted by two or more of the same benzene rings may be the same or different from each other. Moreover, the substitution position of ^R3 is not particularly limited, for example, it can be any one of the 2nd to 7th positions of the oxene ring, usually any of the 2nd, 3rd and 7th positions.

In the aforementioned formula ( ¹ ), the ^substituents represented by R and R include, for example, halogen atoms, hydrocarbon groups, alkoxy groups, cycloalkoxy groups, aryloxy groups, aralkyloxy groups, alkylthio groups, ring Alkylthio, arylthio, aralkylthio, acyl, nitro, cyano, substituted amino, etc.

The aforementioned halogen atom includes fluorine atom, chlorine atom, bromine atom and iodine atom. As a hydrocarbon group, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, etc. are illustrated, for example. Examples of the alkyl group include linear or branched C _{1- 10} alkyl, preferably straight or branched C _1-6 alkyl, more preferably straight or branched C _1-4 alkyl. The cycloalkyl group may, for example, be a C _5-10 cycloalkyl group such as cyclopentyl or cyclohexyl. Examples of the aryl group include _C6-12 aryl groups such as phenyl, alkylphenyl, biphenyl, and naphthyl. Examples of the alkylphenyl group include methylphenyl (cresyl), dimethylphenyl (xylyl), and the like. Examples of the aralkyl group include C _6-10 aryl-C _1-4 alkyl such as benzyl and phenethyl.

Examples of the alkoxy group include linear or branched C _1-10 alkoxy groups such as methoxy, ethoxy, propoxy, n-butoxy, isobutoxy, and 3-butoxy. Base etc. As the cycloalkoxy group, for example, C _5-10 cycloalkoxy group such as cyclohexyloxy group and the like can be exemplified. As the aryloxy group, a C _6-10 aryloxy group such as phenoxy group can be exemplified. Examples of the aralkoxy group include C _6-10 aryl-C _1-4 alkoxy groups such as benzyloxy and the like. Examples of the alkylthio group include C _1-10 alkylthio groups such as methylthio, ethylthio, propylthio, n-butylthio, 3-butylthio, and the like. The cycloalkylthio group may, for example, be a C _5-10 cycloalkylthio group such as cyclohexylthio or the like. As the arylthio group, a C _6-10 arylthio group such as thiophenoxy can be exemplified. Examples of the aralkylthio group include C _6-10 aryl-C _1-4 alkylthio such as benzylthio. Examples of the acyl group include C _1-6 acyl groups such as acetyl and the like. As a substituted amino group, a dialkylamino group, a bis(alkylcarbonyl)amine group, etc. are illustrated, for example. Examples of the dialkylamino group include diC _1-4 alkylamine groups such as dimethylamino groups and the like. Examples of the bis(alkylcarbonyl)amine group include bis(C _1-4 alkyl-carbonyl)amine groups such as diacetylamine groups and the like.

Representative examples of such substituents include halogen atoms; hydrocarbon groups such as alkyl groups, cycloalkyl groups, and aralkyl groups; alkoxy groups; acyl groups; nitro groups; Preferable R ¹ and R ² include, for example, alkyl, cycloalkyl, aryl, alkoxy, etc., and examples of alkyl include linear or branched C _1-6 such as methyl. Alkyl, etc., as cycloalkyl, for example, C _5-8 cycloalkyl such as cyclohexyl, etc., as aryl, for example, C _6-14 aryl such as phenyl, etc., as alkoxy, can Examples thereof include linear or branched C _1-4 alkoxy groups such as methoxy. In particular, examples of the alkyl group include linear or branched C _1-4 alkyl groups such as methyl.

The substitution numbers m1 and m2 of R ¹ and R ² can be selected as long as they are integers of 0 or more, and can be appropriately selected according to the types of Z ¹ and Z ^2. They can be integers such as 0 to 8, respectively. The preferred substitution number m1 And m2 is an integer of 0 to 4, an integer of 0 to 3, an integer of 0 to 2, 0 or 1, preferably 0 in stages. In addition, when the substitution numbers m1 and m2 are 2 or more, the types of 2 or more ^R1 or ^R2 may be the same or different. Especially when m1 and m2 are 1, ^Z1 and ^Z2 are benzene rings, naphthalene rings or biphenyl rings, and ^R1 and ^R2 are preferably methyl groups. Moreover, the substitution position of ^R1 and ^R2 is not particularly limited, as long as it is a position other than the bonding position between ^Z1 and ^Z2 and the ether bond (-O-) and the ninth position of the oxene ring.

In the aforementioned formula (1), examples of A ¹ and A ² include ethylidene, propylidene (1,2-propanediyl), trimethylene, 1,2-butanediyl, tetramethylene Straight-chain or branched C _2-6 alkylene groups, etc. Among them, a linear or branched C _2-4 alkylene group is preferred, a linear or branched C _2-3 alkylene group is more preferred, and ethylene is most preferred.

The repeat numbers (addition mole numbers) n1 and n2 of the oxyalkylene group (OA ¹ ) and the oxyalkylene group (OA ² ) can be integers of 0 or more, for example, 0 to 15, preferably The number of repetitions n1 and n2 is an integer of 0 to 10, 0 to 8, 0 to 6, 1 to 4, 1 to 2 in stages, and 1 is the best. Furthermore, in this specification and the scope of the patent application, the "number of repetitions (number of added moles)" can be the average value (arithmetic mean, summed average) or the average number of added moles, which is a better state Species are the same as the range of preferred integers. When 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, two or more oxyalkylene groups (OA ¹ ) or oxyalkylene groups (OA ² ) may be the same or different, respectively. In addition, the oxyalkylene group (OA ¹ ) and the oxyalkylene group (OA ² ) may be the same as or different from each other.

In the aforementioned 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, as long as they are between Z ¹ and ^Z2 can be replaced by an appropriate substitution position. The substitution ^positions of the group [-O-(A ¹ O) _n1 -H] and the group [-O-(A ² O) _n2 ^-H ] are mostly in the bond In the case of the 2nd, 3rd, 4th, especially the 3rd or 4th position of the phenyl group at the 9th position of the oxene ring, the 4th position is most preferred.

As the stilbene diol represented by the aforementioned formula (1), for example, in the aforementioned formula (1), k=0, n1=0, n2=0 stilbene diol, that is, 9,9-bis(hydroxyaryl ) fennel; k=0, n1 and n2 are 1 or more, preferably 1-10 fenneldiols, that is, 9,9-bis[hydroxy (poly)alkoxyaryl] fennel, etc. Furthermore, in this specification and the scope of the patent application, unless otherwise specified, "(poly)alkoxy" is used to indicate that both alkoxy and polyalkoxy are included.

Examples of 9,9-bis(hydroxyaryl) stilbenes include 9,9-bis(hydroxyaryl) stilbenes such as 9,9-bis(4-hydroxyphenyl) fennel; 9,9-bis( 4-Hydroxy-3-methylphenyl) fluorene, 9,9-bis(4-hydroxy-3-isopropylphenyl) fluorene, 9,9-bis(4-hydroxy-3,5-dimethyl 9,9-bis(hydroxyl-(single or di)C _1-4 alkylphenyl)tilbene, etc.; 9,9-bis(6-hydroxyl-2-naphthyl)tilbene, -Bis (6-hydroxy-1-naphthyl) fluorene, 9,9-bis (5-hydroxy-1-naphthyl) fluorene, etc. 9,9-bis (hydroxynaphthyl) fluorine; 9,9-bis ( 9,9-bis(hydroxyphenylphenyl) fluorine such as 4-hydroxy-3-phenylphenyl) fluorine and the like.

Examples of 9,9-bis[hydroxy (poly)alkoxyaryl] fennels include 9,9-bis[4-(2-hydroxyethoxy)phenyl] fennel, 9,9-bis[ 4-(2-(2-hydroxyethoxy) ethoxy) phenyl] 9,9-bis [hydroxyl (mono- to ten) C _2-4 alkoxy-phenyl] terrene; 9, 9-bis[4-(2-hydroxyethoxy)-3-methylphenyl] fluorene, 9,9-bis[4-(2-(2-hydroxyethoxy)ethoxy)-3- Methylphenyl] fennel, 9,9-bis[4-(2-(2-hydroxyethoxy)ethoxy)-3-isopropylphenyl] fennel, 9,9-bis[4-( 2-Hydroxypropoxy)-3,5-Dimethylphenyl] fluorine and other 9,9-bis[hydroxyl (mono to ten) C _2-4 alkoxy-(mono or di) C _1-4 Alkyl-phenyl] fennel; 9,9-bis[hydroxyl (mono to ten) C _2-4 alkane such as 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl] fennel Oxy-naphthyl] fennel; 9,9-bis[hydroxyl (mono to ten) C _{2- 4} alkoxy-phenylphenyl] terpene, etc.

These terrenediols represented by the aforementioned formula (1) can be used alone or in combination of two or more. Among these stilbene diols, 9,9-bis(hydroxyl-(single or di)C _1-4 alkyl- 9,9-bis[hydroxyl (poly)alkoxyaryl] of phenyl) fennel, 9,9-bis[hydroxyl (mono to ten) C _2-4 alkoxy C _6-10 aryl] fennel, etc. Pertilenes, more preferably 9,9-bis[hydroxy-(mono-penta)C _2-4 alkoxy-phenyl] fennel, most preferably 9,9-bis[4-(2-hydroxyethoxy ) 9,9-bis[hydroxyl (mono or di) C _2-3 alkoxy-phenyl] fennel, etc.

[(A2) Aliphatic diol]

From the viewpoint of formability and the like, the diol (A) may further include an aliphatic diol (A2) in addition to the stilbene diol (A1) represented by the aforementioned formula (1).

Examples of aliphatic diols include ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, tetramethylene glycol (1,4-butanediol Alcohol), 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol _, etc. _-12 alkanediol. These aliphatic diols can be used individually or in combination of 2 or more types.

Among these, linear or branched _C2-6 alkanediols are preferred, and linear or branched C2 alkanediols such as ethylene glycol, propylene glycol, and 1,4-butanediol are more preferred _{. -4} alkanediol, more preferably linear or branched _C2-3 alkanediol such as ethylene glycol, propylene glycol, most preferably ethylene glycol.

The molar ratio of the aforementioned stilbene diol (A1) unit to the aforementioned 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 Periodically 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, optimally 75/25 to 70/30. When the ratio of the aliphatic diol (A2) is too small, the effect of improving the formability may not be found, and conversely, 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 include other diols such as polyalkylene glycols, alicyclic diols, heteroalicyclic diols, and aromatic diols.

Examples of polyalkylene glycols (or polyalkylene glycols) include poly C _2-6 alkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Examples of alicyclic diols include cycloalkanediols such as cyclohexanediol; bis(hydroxyalkyl)cycloalkanes such as cyclohexanedimethanol; Hydrides of diols, etc.

Examples of the heteroalicyclic diol (heterocyclic diol) include derivatives such as isosorbide, isomannide, isoidide, and alkyl-substituted products thereof.

Examples of aromatic diols include dihydroxy aromatic hydrocarbons such as hydroquinone and resorcinol; aromatic diols such as benzenedimethanol; bisphenol F, bisphenol AD, bisphenol A, bisphenol C, bisphenol Bisphenols such as phenol G bisphenol S; bisphenols such as p,p'-bisphenol, etc. Aromatic diol can be C _2-4 alkylene oxide, C _2-4 alkylene carbonate or halogen C _2-4 alkanol adduct. As such an adduct, the adduct etc. which added 2 to 10 mol of ethylene oxide with respect to 1 mol of bisphenol A are mentioned, for example.

These other diols can be used individually or in combination of 2 or more types. Among these, two to four _C2-4 alkanediols such as diethylene glycol, triethylene glycol, and dipropylene glycol are preferred; oxygen-containing heteroalicyclic diols such as isosorbide (oxygen-containing heterocycle Formula diol).

Regarding the ratio of (A3) of other diols, in the resin, the diol (A) may be 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less.

[(B1) Alicyclic dicarboxylic acids]

The dicarboxylic acid component (B) contains alicyclic dicarboxylic acids (B1). In the present invention, the trans-isomer ratio of the alicyclic dicarboxylic acids (B1) is 60 mol% or more of the total dicarboxylic acid component (B), and the high trans-isomer ratio can combine The reverse wavelength dispersion and thinning of the film can also improve the heat resistance. The trans isomer ratio in the resin is more than 60 mol%, and its preferred range is 65 to 99 mol%, 70 to 95 mol%, 75 to 90 mol%, and the best It is 80 to 85 mol%. When the ratio of the trans isomer is too low, both reverse wavelength dispersibility and thinning of the film cannot be achieved. In addition, in the scope of this specification and patent claims, the ratio of trans isomers of alicyclic dicarboxylic acids (B1) can be measured by NMR, and can be measured in detail by the method described in the examples described later.

As alicyclic dicarboxylic acids, cycloalkene dicarboxylic acids, crosslinked cycloalkene dicarboxylic acids, cycloalkene dicarboxylic acids, crosslinked cycloalkene dicarboxylic acids, etc. are mentioned, for example.

As cycloalkanedicarboxylic acids, for example, cyclopentanedicarboxylic acid; 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. cycloalkane dicarboxylic acid; cycloheptane dicarboxylic acid; C _4-12 cycloalkane-dicarboxylic acid such as cyclooctane dicarboxylic acid; ester-forming derivatives of these, etc.

Examples of cross-linked cycloalkanedicarboxylic acids include (di- or tri)cyclocycloalkanes such as decahydronaphthalene dicarboxylic acid, norbornane dicarboxylic acid, adamantane dicarboxylic acid, and tricyclodecane dicarboxylic acid. _7-10 alkane-dicarboxylic acids, ester-forming derivatives thereof, and the like.

As cycloalkene dicarboxylic acids, for example, cyclopentene dicarboxylic acid; cyclohexene dicarboxylic acid such as tetrahydrophthalic acid; C _5-10 cycloalkene-dicarboxylic acid such as cyclooctene dicarboxylic acid ; These ester-forming derivatives, etc.

Examples of the crosslinked cycloalkene dicarboxylic acids include (di- or tri) _cycloC7-10 -dicarboxylic acids such as norcamphene dicarboxylic acid, ester-forming derivatives thereof, and the like.

These alicyclic dicarboxylic acids can be used individually or in combination of 2 or more types. Among these, C _5-10 cycloalkane-dicarboxylic acid is preferred, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid are more preferred Cyclohexanedicarboxylic acid such as alkanedicarboxylic acid or an ester-forming derivative thereof is most preferably 1,4-cyclohexanedicarboxylic acid or an ester-forming derivative thereof. Ester-forming derivatives are preferably C _1-2 alkyl esters such as methyl esters.

In the resin, the ratio of alicyclic dicarboxylic acids (B1) may be 50 mol% or more of the dicarboxylic acid component (B), and its preferable range is 80 mol% or more, 90 mol% or more in stages. % or more, more than 95 mol%, more than 99 mol%, the best is 100 mol%.

[(B2) Aromatic dicarboxylic acids]

In order to improve heat resistance, the dicarboxylic acid component (B) may contain aromatic dicarboxylic acids (B2) in addition to the above-mentioned alicyclic dicarboxylic acids (B1).

Examples of the aromatic dicarboxylic acids (B2) include aromatic hydrocarbon dicarboxylic acids, dicarboxylic acids having a diaryl skeleton, and the like.

Examples of aromatic hydrocarbon dicarboxylic acid components include benzene dicarboxylic acids; alkylbenzene dicarboxylic acids; polycyclic aromatic hydrocarbon dicarboxylic acids such as condensed polycyclic aromatic hydrocarbon dicarboxylic acids and aggregated ring aromatic hydrocarbon dicarboxylic acids. wait.

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

As the alkylbenzenedicarboxylic acids, for example, _C1-4 alkyl-benzenedicarboxylic acids such as methyl terephthalic acid, 4-methylisophthalic acid, and 5-methylisophthalic acid, or Ester-forming derivatives, etc.

As the condensed polycyclic aromatic hydrocarbon dicarboxylic acids, for example, condensed polycyclic C _10-18 aromatic hydrocarbon dicarboxylic acids such as naphthalene dicarboxylic acid, anthracene dicarboxylic acid, phenanthrene dicarboxylic acid or their esters can be mentioned. derivatives, etc. Examples of naphthalene dicarboxylic acid include 1,2-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 1,6-naphthalene dicarboxylic acid, 1,7-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, Naphthalene dicarboxylic acid with two carboxyl groups on different rings of dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, etc.; 1,2-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, etc. Naphthalene dicarboxylic acid having 2 carboxyl groups; ester-forming derivatives thereof, and the like.

As the aggregated ring aromatic hydrocarbon dicarboxylic acids, for example, bis- _{C6- 10} Aromatic dicarboxylic acids, ester-forming derivatives thereof, and the like.

As dicarboxylic acids which have a diaryl skeleton, a diaryl alkane dicarboxylic acid, a diaryl ketone dicarboxylic acid, etc. are mentioned, for example.

Examples of diaryl alkane dicarboxylic acids include diC _6-10 aryl C _1-6 alkane-dicarboxylic acids such as 4,4'-diphenylmethane dicarboxylic acid or ester-forming derivatives thereof. .

Examples of the diaryl ketone dicarboxylic acids include di(C _6-10 aryl) ketone-dicarboxylic acids such as 4,4′-benzophenone dicarboxylic acid or ester-forming derivatives thereof.

These aromatic dicarboxylic acids (B2) can be used individually or in combination of 2 or more types. Among these, benzenedicarboxylic acids, alkylbenzenedicarboxylic acids, and condensed polycyclic C _10-14 aromatic hydrocarbon-dicarboxylic acids are preferred, and terephthalic acid or its ester-forming derivatives are particularly preferred. Ester-forming derivatives are preferably C _1-2 alkyl esters such as methyl esters.

In the case where the dicarboxylic acid component (B) contains aromatic dicarboxylic acids (B2), the molar ratio of the alicyclic dicarboxylic acid (B1) units to the aromatic dicarboxylic acid (B2) units in the resin can be determined from the previous The former/the latter = the range of 99/1 to 50/50, the better range is 98/2 to 60/40, 97/3 to 70/30, 95/5 to 80/20, The best is 93/7 to 85/15. When the ratio of the aromatic dicarboxylic acids (B2) is too large, it may be difficult to achieve both reverse wavelength dispersion and thinning.

[(B3) Other dicarboxylic acids]

The dicarboxylic acid component (B) may contain other dicarboxylic acids (B3) in addition to the above-mentioned alicyclic dicarboxylic acids (B1).

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

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 its ester-forming derivatives, alkanedicarboxylic acids, and the like. Examples of alkanedicarboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, undecanedicarboxylic acid, C _1-18 alkane-dicarboxylic acids such as carboxylic acid and dodecanedicarboxylic acid or their ester-forming derivatives, etc.

Examples of the unsaturated aliphatic dicarboxylic acids include C _2-10 alkene-dicarboxylic acids such as maleic acid, fumaric acid, and methylenesuccinic acid, or ester-forming derivatives thereof.

Examples of the dicarboxylic acids having a terpene skeleton include 9,9-bis(carboxyalkyl) terfenenes, 9-(dicarboxyalkyl) terfenenes, 9,9-bis(carboxyaryl) fennels, bis(carboxyaryl) Carboxy fennels, 9,9-dialkyl-dicarboxy fennels, etc.

Examples of 9,9-bis(carboxyalkyl) fennels include 9,9-bis(2-carboxyethyl) fennel, 9,9-bis(2-carboxypropyl) fennel, etc. Bis(carboxy C _2-6 alkyl) terpene or its ester-forming derivatives, etc.

Examples of 9-(dicarboxyalkyl) fluorines include 9-(dicarboxyethyl) fluorine, 9-(2,3-dicarboxypropyl) fluorine, etc. _2-8 alkyl) tertiles or their ester-forming derivatives, etc.

Examples of 9,9-bis(carboxyaryl) terfenenes include 9,9-bis(carboxy C _6-10 aryl) terfenene such as 9,9-bis(4-carboxyphenyl) terrene or esters thereof. Formative derivatives, etc.

Examples of the dicarboxyl terpine include 2,7-dicarboxy terpine and its ester-forming derivatives.

As 9,9-dialkyl-dicarboxyferenes, for example, 9,9-diC _1-10 alkyl-dicarboxyfenbenes such as 2,7-dicarboxy-9,9-dimethylfenbene or Its ester-forming derivatives, etc.

These other dicarboxylic acids (B3) can be used individually or in combination of 2 or more types. The ratio of other dicarboxylic acids (B3) in the resin can be less than 50 mole % of the dicarboxylic acid component (B), preferably less than 10 mole %, more preferably less than 5 mole %, most preferably It is less than 1 mol%. When the ratio of other dicarboxylic acids (B3) is too large, it may be difficult to achieve both reverse wavelength dispersion and thinning.

[Other thermoplastic resins]

The polymer for the retardation film of the present invention may be a polymer formed of the aforementioned polyester resin alone, but may be a combination of the aforementioned polyester resin and other thermoplastic resins in order to adjust the reverse wavelength dispersion, or improve heat resistance and retardation. polymer alloy. Examples of other thermoplastic resins include polystyrene resins, polycarbonate resins, polyamide resins, polyphenylene ether resins, and polyphenylene sulfide resins. These other thermoplastic resins can be used individually or in combination of 2 or more types. Among these other thermoplastic resins, polycarbonate resins are preferable in terms of optical properties, compatibility with polyester resins, and the like. In particular, the combination of polyester resin and polycarbonate resin can produce a retardation film having both optical properties, heat resistance, and thinness.

As the polycarbonate resin, commonly used polycarbonates such as di- or bisphenol-based aromatic polycarbonates and the like can be utilized.

Examples of diphenols include p,p'-diphenol and the like.

Bisphenols include, for example, bis(hydroxyphenyl)alkanes, bis(hydroxyaryl)cycloalkanes, bis(hydroxyaryl)ethers, bis(hydroxyaryl)ketones, bis(hydroxyaryl) ) sulfides, bis(hydroxyphenyl)sulfides, bis(hydroxyphenyl)sulfides, etc.

Examples of bis(hydroxyphenyl)alkanes include bis(4-hydroxyphenyl)methane (bisphenol F), 1,1-bis(4-hydroxyphenyl)ethane (bisphenol AD), 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-methylbutane, 2,2-bis(4-hydroxyxylyl)propane and other bis(hydroxyphenyl)C _1-6 alkanes, etc. .

Examples of bis(hydroxyaryl)cycloalkanes include bis(hydroxyl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)cyclopentane and 1,1-bis(4-hydroxyphenyl)cyclohexane. Aryl) C _4-10 naphthenes, etc.

As bis(hydroxyaryl) ethers, bis(4-hydroxyphenyl)ether etc. are mentioned, for example.

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

Examples of bis(hydroxyphenyl)pyridines include bis(4-hydroxyphenyl)pyrone (bisphenol S) and the like.

As the bis(hydroxyphenyl)phenylenes, bis(4-hydroxyphenyl)phenylenes, etc. are mentioned, for example.

As bis(hydroxyphenyl)sulfides, bis(4-hydroxyphenyl)sulfide etc. are mentioned, for example.

These di- or bisphenols may also be C _2-4 alkylene oxide adducts. These di or bisphenols can be used individually or in combination of 2 or more types. Among these two or bisphenols, bis(hydroxyaryl) C _1-6 alkane such as bisphenol A is preferred.

The polycarbonate resin may also be a polyester polycarbonate resin in which a dicarboxylic acid component (aliphatic, alicyclic or aromatic dicarboxylic acid or its acyl halide, etc.) is copolymerized. These polycarbonate resins can be used individually or in combination of 2 or more types. A preferred polycarbonate resin is a resin based on bis(hydroxyphenyl) C _1-6 alkanes, such as bisphenol A polycarbonate resin.

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

The ratio of the polycarbonate resin can be appropriately selected according to the target optical properties, heat resistance, etc., and can be selected from the range of 0.1 to 100 parts by mass for 100 parts by mass of the polyester resin, for example, 0.5 to 30 parts by mass Parts, preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, most preferably 2.5 to 5 parts by mass.

[Polymers for Retardation Films]

The polymer for the retardation film of the present invention only needs to contain the polyester resin obtained by reacting the aforementioned diol (A) and the aforementioned dicarboxylic acids (B) as polymerization components. Polymer alloys of polyester resins and other thermoplastic resins, especially polymer alloys of polyester resins and polycarbonate resins.

The polyester resin represented by the aforementioned formula (1) contained in the retardation film polymer of the present invention can be used by commonly used methods, such as melt polymerization methods such as transesterification and direct polymerization; liquid polymerization; interfacial polymerization Such as aggregation and modulation. Among these methods, the melt polymerization method is preferable. Furthermore, depending on the polymerization method, the reaction may be performed in the presence or absence of a solvent.

The use ratio (or preparation ratio) of diol (A) and dicarboxylic acid component (B) is usually former/latter (molar ratio)=1/1.2 to 1/0.8, preferably 1/1.1 to 1/ 0.9. Furthermore, the amount (use ratio) of each diol (A) and dicarboxylic acid component (B) used in the reaction can be the same as the ratio of the aforementioned diol units and dicarboxylic acid units in the resin, which includes preferably As needed, each component can be used in excess to carry out the reaction. For example, diols (A2) such as ethylene glycol distilled from the reaction system can be used in a larger amount than the ratio (or introduction ratio) introduced into the polyester resin.

The reaction can also be carried out in the presence of a catalyst. A metal catalyst, which is a commonly used esterification catalyst, can be used as the catalyst. 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; metals of group 13 of the periodic table such as aluminum can be used. ; metals of group 14 of the periodic table such as germanium; metal compounds of group 15 metals of the periodic table such as antimony. Metal compounds may be alkoxides; organic acid salts such as acetates and propionates; inorganic acid salts such as borates and carbonates; metal oxides may be hydrates thereof.

Typical metal compounds include germanium compounds such as germanium dioxide, germanium hydroxide, germanium oxalate, tetraethoxygermanium, and germanium n-butoxide; antimony compounds such as antimony trioxide, antimony acetate, and antimony glycolate; Compounds; titanium compounds such as tetra-n-propyl titanate, tetraisopropyl titanate, and tetra-n-butyl titanate; manganese compounds such as manganese acetate tetrahydrate; calcium compounds such as calcium acetate monohydrate.

These catalysts can be used individually or in combination of 2 or more types. When using a plurality of catalysts, each catalyst can be added according to the progress of the reaction. Among these catalysts, manganese acetate tetrahydrate, calcium acetate monohydrate, and germanium dioxide are preferred.

The amount of the catalyst used is, for example, 0.01×10 ^-4 to 100×10 ^-4 mole, preferably 0.1×10 ^-4 to 40×10 ^-4 mole relative to 1 mole of the dicarboxylic acid component (B).

Furthermore, 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, phosphorous acid, trimethyl phosphite, triethyl phosphite, etc., if necessary. The amount of the stabilizer is, for example, 0.01×10 ^-4 to 100×10 ^-4 moles, preferably 0.1×10 ^-4 to 40×10 ^-4 moles relative to 1 mole of the dicarboxylic acid component (B) .

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

When the polymer for the retardation film of the present invention is a polymer alloy, polycarbonate resin contained in the polymer alloy can be produced by a common method such as phosgene method (solvent method), transesterification method (melt method), etc. .

The glass transition temperature Tg of the polymer for the retardation film of the present invention can be selected from the range of 50 to 200°C, and the preferred range is 70 to 180°C, 80 to 160°C, and 100 to 150°C in stages , 110 to 145°C, 115 to 142°C, 120 to 140°C, most preferably 130 to 135°C. When the aforementioned polymer is a polymer alloy, since the polymer alloy is likely to be completely compatible, it may also have one glass transition temperature Tg. If the glass transition temperature Tg is too low, the heat resistance may decrease, and the resin may be deformed or discolored (or colored) during use. If the Tg is too high, the formability may decrease. In addition, in the scope of this specification and patent application, glass transition temperature Tg can be measured by the method etc. which are described in the example mentioned later.

The polymer for retardation films of the present invention has a characteristic of high molecular weight (weight average molecular weight Mw, etc.). The weight-average molecular weight Mw of the polymer for the phase difference 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. The optimal range is 40,000 to 150,000, 50,000 to 100,000, 55,000 to 90,000 in stages, and the best range is 60,000 to 80,000. When the aforementioned 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, more preferably 50,000 to 60,000. The aforementioned polymers have high molecular weight and polymerization degree (molecular chain length), and good mechanical properties (elongation at break, elasticity, etc.). In addition, in the scope of this specification and patent application, the weight average molecular weight Mw can be measured in terms of polystyrene by gel permeation chromatography (GPC).

The refractive index of the polymer for the retardation film of the present invention can be selected from the range of 1.50 to 1.65 at a temperature of 20°C and a wavelength of 589nm, and the preferred range is 1.52 to 1.64, 1.54 to 1.63, 1.56 to 1.62, the best is 1.58 to 1.618.

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

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

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, most preferably 150 to 155°C.

The weight average molecular weight Mw of the polycarbonate resin is, for example, 10,000 to 100,000, preferably 30,000 to 80,000, more preferably about 50,000 to 70,000.

Regarding the complex refractive index of the polymer for retardation film, it can be based on the complex refractive index of the stretched film formed by stretching a film formed of polyester alone or a film formed of a polymer alloy at a stretching ratio of 3 times (3 times birefringence rate) for evaluation. The complex refractive index (three-fold complex refractive index) is represented by the absolute value of the difference between the refractive index in the film in-plane extending direction and the refractive index perpendicular to the direction. Therefore, the 3-fold complex refractive index of the stretched film prepared under the 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 +50×10 ^-4 , preferably 0×10 ^-4 to +25×10 ^-4 , more preferably 0×10 ^-4 to +20×10 ^-4 .

The polymer for retardation films of the present invention may contain various commonly used additives as long as the effects of the present invention are not impaired. Commonly used additives include, for example, polymerization initiators; plasticizers such as esters, phthalic acid compounds, epoxy compounds, and sulfonamides; inorganic flame retardants, organic flame retardants, colloidal flame retardants, etc. Flame retardants for substances, etc.; stabilizers such as light stabilizers and antioxidants; antistatic agents; fillers for oxide-based inorganic fillers, non-oxide-based inorganic fillers, metal powders, etc.; foaming agents; defoamers lubricants; release agents for natural waxes, synthetic waxes, straight-chain fatty acids or their metal salts, acid amides, etc.; slipperiness imparting agents. Examples of slipperiness-imparting agents include inorganic particles such as silicon oxide, titanium oxide, calcium carbonate, clay, mica, and kaolin; (meth)acrylic resins, styrene resins (cross-linked polystyrene resins, etc.) and other organic particles. These additives can be used individually or in combination of 2 or more types.

The ratio of these commonly used additives is, for example, 30 parts by mass or less, preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the polymer for retardation films.

These additives can be added using a common method, such as a single-screw or two-screw extruder (preferably a two-screw extruder from the viewpoint of dispersion), and can also be melt-kneaded with a polymer for a retardation film. Add these additives by the method. Additives can be added before the polymer for retardation film is formed, but for example, when the polymer for retardation film is melt-formed, an extrusion process for supplying the polymer for retardation film to the film-forming device is used. It is preferable that the equipment melt-kneads the additive because it is economically advantageous.

[Retardation film and its manufacturing method]

The retardation film of the present invention is formed and stretched from the aforementioned polymer for retardation film. 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)×d

(In the formula, nx represents the refractive index in the direction of the slow axis of the film, ny represents the refractive index in the direction of the fast axis, and d represents the thickness of the film).

The in-plane retardation of wavelength λnm is expressed as Rλ. At a temperature of 20°C, a thickness of 50μm, and a wavelength of 550nm, the in-plane retardation R550 can be selected from the range of 100 to 160nm, and its better range is staged as 110 to 155nm, 110 to 150nm, 115 to 148nm, 120 to 145nm, 130 to 142nm, most preferably 135 to 140nm. Furthermore, in this specification and the scope of the patent application, the in-plane retardation with a thickness of 50 μm is the front retardation of a film with a thickness of 50 μm, and the in-plane retardation of a film with a thickness d is converted into a value with a thickness of 50 μm.

The retardation film of the present invention has reverse wavelength dispersion characteristics. Therefore, the ratio R450/550 of the in-plane retardation R450 at a wavelength of 450 nm to the aforementioned in-plane retardation R550 is 0.8 to less than 1, preferably 0.802 to 0.95, more preferably 0.805 to 0.92, 0.808 to 0.9, 0.81 to 0.88 , 0.812 to 0.87, the best is 0.815 to 0.86. Furthermore, for an ideal broadband 1/4 wavelength plate, R450/R550 is about 0.818.

The retardation film of the present invention not only exhibits reverse wavelength dispersion, but also can be thinned. The average thickness of the retardation film of the present invention may be less than 100 μm, preferably less than 60 μm, more preferably less than 50 μm, further preferably less than 40 μm, most preferably less than 35 μm. 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, further preferably 28 to 37 μm, most preferably 30 to 35 μm. When the average thickness is too small, the coiling properties during film production may decrease, stable coiling may not be possible, and cracking may occur in the stretching step. Moreover, since the phase difference is proportional to the film thickness, it may reduce the performance of the phase difference. On the other hand, if the average thickness is too large, it may not be able to meet the thin requirements of the circular polarizer, and may warp during drying during the step of laminating with the polarizer, which may hinder the optical properties of the final polarizer.

The phase difference film of the present invention is obtained through a film forming step of obtaining a film by extrusion molding or solution casting film forming, and a stretching step of extending the film obtained in the aforementioned film forming step.

In the film production step, as a film production method, it can be prepared by, for example, casting film method (solution casting method), extrusion method (melt extrusion method such as inflation method and T-die method), calendering method, etc. From the viewpoint that a long resin film can be easily produced, and continuous production can be easily achieved through a stretching step such as uniaxial stretching, extrusion such as a melt extrusion method using a T-die is preferable. Extrusion molding method, solution casting molding method, extrusion molding is more suitable. In the melt extrusion method, molding conditions can be adjusted according to the glass transition temperature and melting point of the polymer for retardation films, and molding can be performed by a usual 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, 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 extension can be uniaxial extension, biaxial extension, or oblique extension.

The stretching temperature can be a temperature above the glass transition temperature (Tg) and below the melting point of the polymer for retardation film constituting the film, and the preferred range is from Tg to Tg+30°C, Tg+1 to Tg+20 in stages. °C, Tg+2 to Tg+10°C, Tg+3 to Tg+8°C, the best is Tg+4 to Tg+7°C. When the stretching temperature is too high, the relaxation of the alignment is strong, and a sufficient phase difference may not be found. Conversely, when the temperature is too low, the phase difference may be easily found, but it may be broken.

The elongation magnification can be selected from the range of 2 to 5 times, for example, the preferred range is 2.5 to 5 times, 2.8 to 5 times, 3 to 4.5 times, and the best range is 3.5 to 4 times. When the elongation magnification is too low, sufficient phase difference may not be found, and on the contrary, if it is too high, it may be broken.

[Circular Polarizer and Image Display Device]

The retardation film of the present invention is directly attached to a polarizer (polarizer) as a 1/4 wavelength retardation film, thereby forming a circular polarizer. Polarizers generally use polyvinyl alcohol (PVA) films.

In order to improve the adhesion between the retardation film obtained by the aforementioned method and the polarizer, corona treatment, plasma treatment, and surface modification treatment with strong alkali aqueous solution such as sodium hydroxide or potassium hydroxide can also be performed simultaneously. Furthermore, thin films such as an undercoat layer may be formed on the surface of the retardation film. The surface modification treatment or the formation of the thin film can be carried out after the film forming step, or after the oblique stretching step.

The circular polarizing plate of the present invention may be a laminate of the aforementioned retardation film and polarizer, and a transparent protective film is usually laminated on the opposite side of the retardation film laminate layer of the polarizer. As long as the transparent protective film is an optically transparent material with high adhesiveness to a polarizer such as a PVA film, from the viewpoint of transparency, high mechanical strength, and low optical anisotropy, three types of protective film are generally used. Acetyl cellulose (TAC) film, cellulose ester film such as cellulose acetate propionate film, modified acrylic resin film, ultra-high birefringence polyethylene terephthalate resin film, Cycloolefin films, etc.

Adhesives may also exist between the layers of the circular polarizing plate of the present invention. Generally, water-based adhesives can be used as adhesives. 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. Among these, polyvinyl alcohol-based adhesives are preferred.

The image display device of the present invention has the obtained circular polarizing plate as an optical film. Examples of the image display device of the present invention include liquid crystal display devices, organic EL displays, and the like.

[Example]

The following examples illustrate the present invention in more detail, but the present invention is not limited to these examples. The evaluation method is as follows.

[NMR]

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 Co., Ltd.), the sample was put 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 a gel permeation chromatography (manufactured by Tosoh Co., Ltd., "HPC-8120GPC").

[The average thickness]

Measured with a thickness meter (Mitutoyo Co., Ltd. product "Micrometer"). In addition, the average thickness was measured at three points at equal intervals between the clips in the longitudinal direction of the film, and the average value was calculated.

[phase difference]

The in-plane retardation R450 and R550 of the reverse wavelength dispersive film and the wavelength dispersion characteristics R450/R550 of the retardation are measured at wavelengths of 450nm and 550nm using a retarded phase measuring device ("RETS-100" manufactured by Otsuka Electronics Co., Ltd.). Determination.

Example 1

(Synthesis of Copolymerized Polyester Resin)

While adding and stirring 9,9-bis[4-(2-hydroxyethoxy)phenyl] fennel (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, 1,4-cyclohexanedicarboxylic acid dimethyl ester (trans isomer ratio 98 mol%, hereinafter referred to as "CHDA-M") 1.0 mol, as esterification Manganese acetate tetrahydrate 2×10 ^-4 mol and calcium acetate monohydrate 8×10 ^-4 mol as catalyst, while slowly heating and melting, after heating up to 230°C, add triethyl phosphate 14×10 ^-4 mol Ear, germanium oxide 20×10 ^-4 mol, while gradually raising the temperature, reducing the pressure until 270°C and 0.13KPa, while removing ethylene glycol. After reaching a specified stirring torque, the contents were taken out from the reactor to obtain pellets of polyester resin. When the obtained particles 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 isomer of CHDA-M, and 17 mol % was derived from the cis isomer of CHDA-M. The obtained polyester resin had a glass transition temperature Tg of 120°C and a Mw of 61,400.

(Film formation of reverse wavelength dispersive film)

Supply the obtained resin pellets to a two-axis extrusion device (screw diameter 40mm, L/D=32) equipped with a T-shaped die, extrude a film with an effective width of 200mm at a cylinder temperature of 260°C and wind it into a roll shape. Its thickness is 150 μm.

(uniaxial extension processing)

Using a stretching device (Imoto Seisakusho Co., Ltd. "Membrane Biaxial Stretcher IMC-1A97"), a uniaxially stretched film was produced under the stretching conditions of a temperature of 123°C and a magnification of 3.5 times, and the average thickness and retardation of the obtained film were measured. .

Examples 2 to 5

Copolymerized polyester was produced in the same manner as in Example 1 except that the modulation ratio was changed, and after Tg and Mw were measured, a reverse wavelength dispersive film was produced in the same manner as in Example 1 except that the stretching conditions were changed, and the average thickness and retardation thereof were measured. .

Examples 6 to 8

Except for adding dimethyl terephthalate (hereinafter referred to as "DMT") as a monomer and changing the preparation ratio, the copolymerized polyester was produced in the same manner as in Example 1. After measuring Tg and Mw, except for changing the stretching conditions, A reverse wavelength dispersive film was produced in the same manner as in Example 1, and its average thickness and retardation were measured.

Examples 9 to 12

To 100 parts by mass of the obtained resin pellets, 1 to 4 parts by mass of polycarbonate ("IUPILON E-2000" manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was added, and a film with an effective width of 200 mm was extruded in the same manner as in Example 4 ( Thickness: 60 to 100 μm), after winding up into a roll, except changing the stretching conditions, a reverse wavelength dispersive film was produced in the same manner as in Example 4, and the average thickness and phase difference were measured. In addition, in Table 1, the glass transition temperature Tg and weight average molecular weight Mw of Examples 9-12 are Tg and Mw of the polymer alloy formed into a film.

Comparative Examples 1 to 2

Except using 1,4-cyclohexanedicarboxylic acid (trans-isomer ratio 30 mol%, hereinafter referred to as "CHDA") instead of CHDA-M and changing the modulation ratio, a copolyester was produced in the same manner as in Example 1 After polymerizing the polyester and measuring Tg and Mw, a reverse wavelength dispersive film was produced in the same manner as in Example 1 except that the stretching conditions were changed, and the average thickness and retardation thereof were measured.

Examples and Comparative Examples

The evaluation results are shown in Table 1.

From the results in Table 1, it is obvious that the examples have high heat resistance, thin walls, and reverse wavelength dispersion, while the comparative examples cannot simultaneously satisfy heat resistance, thin walls, and reverse wavelength dispersion. In particular, Examples 3 to 4 and 11 to 12 are preferable in various required applications. In Example 3, thin walls and high inverse wavelength dispersion are achieved. Furthermore, in Example 4, the heat resistance and reverse wavelength dispersibility were high. Furthermore, in Examples 11 and 12, thin wall and high heat resistance were achieved.

[industrial availability]

The polymer for a retardation film of the present invention can be adjusted to have wavelength dispersion characteristics with a negative retardation across a wide band of visible light by stretching. Therefore, a 1/4 wavelength plate [for example, a 1/4 wavelength plate that functions over a wide frequency band spanning visible light (the entire range of visible light, etc.)) can be suitably utilized. Furthermore, by laminating a retardation film formed of the polymer for retardation film of the present invention and a polarizing plate, a circular polarizing plate excellent in anti-reflection and broadband can be produced. The aforementioned circular polarizing plate is suitable for use in image display devices (such as reflective liquid crystal display devices, transflective liquid crystal display devices, organic EL display devices, etc.).

Claims (10)

A kind of polymer for phase difference film, is to comprise polyester resin, and this polyester resin contains the diol (A) that comprises the stilbene diol (A1) and aliphatic diol (A2) represented by following formula (1), and A dicarboxylic acid component (B) comprising alicyclic dicarboxylic acids (B1) as a polymerization component, wherein the molar ratio of the stilbene diol (A1) to the aliphatic diol (A2) is the former/the latter=91 /9 to 10/90; the aforesaid aliphatic diol (A2) is a linear or branched _C2-12 alkanediol; the trans isomer ratio of the aforesaid cycloaliphatic dicarboxylic acids (B1) is the aforesaid 60 mol % or more and 89 mol % or less of the whole dicarboxylic acid component (B);

In the formula, Z ¹ and Z ² represent the same or different aromatic hydrocarbon rings, R ¹ and R ² represent the same or different substituents, A ¹ and A ² represent the same or different alkylene groups, R ³ represents the substituent , m1 and m2 represent the same or different integers of 0 or more, n1 and n2 represent the same or different integers of 0 or 1 or more, and k represents an integer of 0 to 8. The polymer for retardation film according to claim 1, wherein the dicarboxylic acid component (B) further includes aromatic dicarboxylic acids (B2). The polymer for phase difference film as described in item 1 or 2 of the patent claims is a polymer alloy of the aforementioned polyester resin and polycarbonate resin. A retardation film, which is formed by stretching the polymer for the retardation film described in any one of the first to third claims of the patent application. The retardation film described in item 4 of the scope of the patent application has an average thickness of 100 μm or less. A method for manufacturing the retardation film described in item 4 or 5 of the scope of the patent application, comprising: a film forming step of obtaining a film by extrusion molding or solution casting film forming, and performing the film obtained in the aforementioned film forming step Extended extension steps. The method for manufacturing a retardation film as described in item 6 of the scope of the patent application, wherein the stretching ratio of the aforementioned stretching step is 2 to 5 times. A circular polarizing plate, which is formed by laminating the retardation film and polarizer described in item 4 or 5 of the scope of the patent application. An image display device comprising the circular polarizing plate described in item 8 of the patent application. The image display device described in item 9 of the patent application is an organic electroluminescent (EL) display.