JP6799623B2 - Polycarbonate resin and optical film - Google Patents

Description

The present invention relates to a polycarbonate resin and an optical film, and relates to a polycarbonate resin having desired wavelength dispersion characteristics, a low photoelastic constant, high heat resistance, and excellent melt processability, and an optical film formed from the polycarbonate resin.

Generally, an optical film, particularly a retardation film, is used in a display device such as a liquid crystal display device, and has functions such as color compensation, viewing angle enlargement, and antireflection.

Known retardation films include λ / 4 plates and λ / 2 plates, and as the material thereof, thermoplastic polymers such as polycarbonate, polyether sulfone, and polysulfone obtained by polycondensing bisphenol A are used. The λ / 4 plate and λ / 2 plate obtained by stretching a film of these materials have a property that the shorter the wavelength, the larger the phase difference. Therefore, there is a problem that the wavelengths that can function as the λ / 4 plate and the λ / 2 plate are limited to specific wavelengths.

As a method of controlling the wavelength in a wide band, a method of laminating two or more specific birefringent films having different wavelength dependences of phase difference at a specific angle is known. (For example, refer to Patent Document 1) In these cases, since a plurality of retardation films are used, a step of bonding them or adjusting the bonding angle is required, which causes a problem in productivity. Further, since the thickness of the entire retardation film is increased, there is also a problem that the light transmittance is lowered and the film becomes thicker or darker when incorporated in the apparatus.

In recent years, a method of widening the bandwidth with a single film without such lamination has been proposed (see Patent Document 2). The film is a method of stretching a polymer film composed of a polymer monomer unit having a positive refractive index anisotropy and a polymer monomer unit having a negative refractive index anisotropy. However, since the specifically disclosed film has a high photoelastic constant, there is a problem that birefringence due to stress is large and light leakage occurs when it is used as a retardation film. Further, since an aromatic polycarbonate having a fluorene-based bisphenol skeleton is used, there is a problem that a gel product is likely to be generated due to decomposition because the melting temperature is high in the case of melt processing. Also. Since it has a high Tg (glass transition temperature), it requires a high temperature for stretching the film, etc., and requires special processing equipment different from the conventional one, so the workability is not always sufficient. Absent.

As a film that can be melt-formed with a low photoelastic constant, a polycarbonate copolymer of 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, isosorbide, and an aliphatic diol and 9,9-bis [4] -(2-Hydroxyethoxy) phenyl] A retardation film or the like using a polycarbonate copolymer of fluorene and isosorbide has been reported (see Patent Documents 3 and 4). Further, although a retardation film using a polycarbonate copolymer containing spirobiindane has been reported, it has a high photoelastic constant and does not describe wavelength dispersibility (see Patent Document 5).

Japanese Unexamined Patent Publication No. 02-120804 International Publication 2000/026705 Pamphlet International Publication 2006/0411 90 Pamphlet Japanese Unexamined Patent Publication No. 2010-134232 Japanese Unexamined Patent Publication No. 2006-131789

An object of the present invention is to provide a polycarbonate resin having a wavelength dispersion characteristic close to an ideal wide band, high phase difference expression, low photoelasticity, and excellent melt processability, and an optical film formed from the polycarbonate resin. is there.

As a result of diligent studies to achieve this object, the present inventors have obtained a film made of a polycarbonate resin obtained by using a combination of specific monomers, which has an inverse wavelength dispersibility close to an ideal wide band and is photoelastic. We have found that it is a retardation film having a low coefficient, and have reached the present invention.

That is, the present invention is as follows.
The carbonate unit (A) derived from 1.6,6'-dihydroxy-3,3,3', 3'-tetramethyl-1,1'-spirobiindan and 3,9-bis (2-hydroxy-1). , 1-Dichloromethane) -2,4,8,10-Tetraoxaspiro (5.5) Containing carbonate unit (B) derived from undecane (but not containing carbonate unit derived from isosorbide) , The molar ratio (A / B) of the unit (A) to the unit (B) is 5/95 to 50/50 or 60/40 to 95/5 , and the specific viscosity measured in a methylene chloride solution at 20 ° C. Polycarbonate resin of 0.25 to 0.45.
2. 2. The polycarbonate resin according to item 1 above, wherein the glass transition temperature of the polycarbonate resin is 70 ° C to 180 ° C.
3. 3. The polycarbonate resin according to item 1 above, wherein the photoelastic constant of the polycarbonate resin is 40 × 10 ^-12 Pa ^-1 or less.
4. The polycarbonate resin according to item 1 above, further containing a carbonate unit (C) derived from a dihydroxy compound having a fluorene skeleton.
5. An optical film formed from the polycarbonate resin according to any one of the above items 1 to 4.
6. The optical film according to item 5 above, wherein the optical film is formed by a melt extrusion method.
7. 5. The optical film according to item 5, wherein the optical film is a retardation film formed by stretching an unstretched film.
8. The optical film according to item 7 above, wherein the in-plane retardation values R (450), R (550), and R (650) at wavelengths of 450 nm, 550 nm, and 650 nm satisfy the following formulas (1) and (2).
0.60 ≤ R (450) / R (550) ≤ 1.00 (1)
1.01 ≤ R (650) / R (550) ≤ 1.40 (2)
9. A liquid crystal display device or an organic EL display device provided with the optical film according to item 8 above.

The optical film of the present invention is composed of a polycarbonate copolymer resin having a low photoelastic constant, high transparency, and excellent processability, has a desired wavelength dispersibility by stretching treatment, and can be widened by a single film. Therefore, it is extremely useful as an optical film for liquid crystal display devices, organic EL displays, and the like.

It is explanatory drawing of the thermal unevenness evaluation of an Example.

Hereinafter, the present invention will be described in detail.
<Polycarbonate resin>
The present invention is formed from a polycarbonate resin containing a unit (A) and a unit (B).

(Unit (A))
The unit (A) is represented by the following formula.

In the unit (A), R ₁ and R ₂ each independently represent a hydrogen atom, a hydrocarbon group or a halogen atom which may contain an aromatic group having 1 to 10 carbon atoms. As the hydrocarbon group, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, and an alkenyl group having 1 to 10 carbon atoms. Can be mentioned. Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom. W represents a single bond, a carbon atom, an oxygen atom, and a sulfur atom.
Preferred examples of the compound for inducing the unit (A) include 6,6'-dihydroxy-3,3,3', 3'-tetramethyl-1,1'-spirobiindane and spirobichroman.

(Unit (B))
The unit (B) is a carbonate unit derived from a diol compound which is an aliphatic diol compound and / or an alicyclic diol compound. Examples of the aliphatic diol compound and the alicyclic diol compound include the diol compounds described in International Publication No. 2004/11106 and International Publication No. 2011/021720, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol and the like. Examples thereof include oxyalkylene glycols.

Examples of the aliphatic diol compound include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, and 1.9-nonanediol. 1,10-decanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-n-butyl-2-ethyl- 1,3-Propanediol, 2,2-diethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexaneglycol, 1,2-octylglycol, 2-ethyl -1,3-Hexanediol, 2,3-diisobutyl-1,3-propanediol, 2,2-diisoamyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, etc. Can be mentioned.

Examples of the alicyclic diol compound include cyclohexanedimethanol, tricyclodecanedimethanol, adamantandiol, pentacyclopentadecanedimethanol, and 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4. Examples include 8,10-tetraoxaspiro [5.5] undecane, isosorbide, 2,2,4,4-tetramethyl-1,3-cyclobutanediol and the like.

As the diol compound, an alicyclic diol is preferable, and cyclohexanedimethanol, tricyclodecanedimethanol, 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxa Spiro [5.5] undecane and isosorbide are more preferred, with 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane and isosorbide. , 2,2,4,4-tetramethyl-1,3-cyclobutanediol are particularly preferred.
In addition, a part of polyester carbonate can be obtained by copolymerizing the acid component.

(Unit (C))
The unit (C) is a carbonate unit (which may include some ester units) derived from a dihydroxy compound having a fluorene skeleton.
As the unit (C), a carbonate unit represented by the following formula (C1) is preferably used.

In the unit (C1), R ₃ and R ₄ each independently represent a hydrogen atom, a hydrocarbon group or a halogen atom which may contain an aromatic group having 1 to 10 carbon atoms. As the hydrocarbon group, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, and an alkenyl group having 1 to 10 carbon atoms. Can be mentioned. Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom.

R ₅ and R ₆ each independently represent a hydrocarbon group that may contain an aromatic group having 1 to 10 carbon atoms. The hydrocarbon group is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and more preferably an ethylene group.
p and q represent the number of repetitions of-(R _5- O)-and-(OR ₆ )-, respectively. p and q are each independently an integer of 0 or greater, preferably an integer of 0 to 20, even more preferably an integer of 0 to 12, even more preferably an integer of 0 to 8, particularly preferably 0 to 4. An integer of, most preferably 0 or 1.
m and n each independently represent an integer of 0-4.

（Ｒ_３およびＲ_４は単位（Ｃ１）と同じである。） (When p and q are 0)
When p and q are 0, the unit (C1) is expressed by the following formula (hereinafter, may be referred to as a unit (C1a)).

(R ₃ and R ₄ are the same as the unit (C1).)

As the unit (C1a), 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 9,9-bis (4-hydroxy-3-ethylphenyl) ) Fluorene, 9,9-bis (4-hydroxy-3-n-propylphenyl) fluorene, 9,9-bis (4-hydroxy-3-isopropylphenyl) fluorene, 9,9-bis (4-hydroxy-3) -N-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-sec-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-tert-butylphenyl) fluorene, 9,9- Examples thereof include units derived from bis (4-hydroxy-3-cyclohexylphenyl) fluorene, 9,9-bis (4-hydroxy-3-phenylphenyl) fluorene and the like. The compounds for inducing these units (C1a) may be used alone or in combination of two or more.

In particular, the unit (C1a-i) represented by the following formula derived from 9,9-bis (4-hydroxy-3-methylphenyl) fluorene is preferable.

The polycarbonate copolymer containing the unit (C1a-i) has a b value of preferably 6.0 or less, more preferably 5.5 or less, and further, a solution obtained by dissolving 10 g of the polycarbonate copolymer in 50 ml of ethanol and measuring with an optical path length of 30 mm. It is preferably 5.0 or less. When this b value is within the above range, the optical film formed from the polycarbonate copolymer has a good hue and high strength.

The raw material for the unit (C1a-i), 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, is obtained by the reaction of o-cresol with fluorenone. 9,9-bis (4-hydroxy-3-methylphenyl) fluorene having a small b value can be obtained by removing impurities.

Specifically, after the reaction of o-cresol and fluorenone, unreacted o-cresol is distilled off, and then the residue is dissolved in an alcohol-based, ketone-based or benzene derivative-based solvent, and activated clay or activated charcoal is added thereto. In addition, after filtration, the crystallized product from the filtrate can be filtered to give purified 9,9-bis (4-hydroxy-3-methylphenyl) fluorenone. Impurities to be removed include 2,4'-dihydroxy form, 2,2'-dihydroxy form, and impurities of unknown structure. As the alcohol-based solvent used for such purification, lower alcohols such as methanol, ethanol, propanol and butanol are preferable. As the ketone solvent, lower aliphatic ketones such as acetone, methyl ethyl ketone, methyl isopropyl ketone and cyclohexanone and mixtures thereof are preferable. As the benzene derivative solvent, toluene, xylene, benzene and a mixture thereof are preferable. The amount of the solvent used is sufficient as long as the amount of the fluorene compound is sufficiently dissolved, and is usually about 2 to 10 times the amount of the fluorene compound. As the activated clay, commercially available powdered or granular silica-alumina as a main component is used. As the activated carbon, commercially available powdered or granular activated carbon is used.

（Ｒ_３、Ｒ_４、Ｒ_５、Ｒ_６、ｍおよびｎは単位（Ｃ１）と同じである。ｐおよびｑは、夫々独立して、１以上の整数である。） (When p and q are integers greater than or equal to 1)
When p and q are integers of 1 or more, the unit (C1) is expressed by the following formula (hereinafter, may be referred to as a unit (C1b)).

_{(R 3, R 4, R} 5, R 6, m and n are the same as the unit (C1) .p and q are each independently an integer of 1 or more.)

As the unit (C1b), 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [4- (3-hydroxypropoxy) phenyl] fluorene, 9,9-bis [4- (4-Hydroxybutoxy) phenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-methylphenyl] fluorene, 9,9-bis [2- (2-hydroxyethoxy) -5-methyl Phenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-ethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-propylphenyl] fluorene, 9, 9-bis [4- (2-hydroxyethoxy) -3-isopropylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-n-butylphenyl] fluorene, 9,9-bis [ 4- (2-Hydroxyethoxy) -3-isobutylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3- (1-methylpropyl) phenyl] fluorene, 9,9-bis [4 -(3-Hydroxypropoxy) -3-methylphenyl] fluorene, 9,9-bis [4- (4-hydroxybutoxy) -3-methylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) ) -3,5-Dimethylphenyl] Fluorene, 9,9-bis [4- (2-hydroxyethoxy) -2,5-dimethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy)- 3,5-diethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-dipropylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3 , 5-Diisopropylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-di-n-butylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy)) -3,5-diisobutylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-bis (1-methylpropyl) phenyl] fluorene, 9,9-bis [4- (3) -Hydroxypropoxy) -3,5-dimethylphenyl] fluorene, 9,9-bis [4- (4-hydroxybutoxy) -3,5-dimethylphenyl] fluorene, 9,9-bis [4- (2-hydroxy) Ethoxy) -3-cyclohexylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-diphenylphenyl] fluorene, 9,9- Bis [4- (2-hydroxyethoxy) -3-benzylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-dibenzylphenyl] fluorene, 9,9-bis [4 -(2-Hydroxyethoxy) -3-propenylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-fluorophenyl] fluorene, and these 9,9-bis (hydroxyalkoxyphenyl) Examples include units derived from fluorene. Further, a unit derived from 9,9-bis [hydroxypoly (alkyleneoxy) phenyl] fluorene having p and q of 2 or more can be mentioned.

Of these, 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-methylphenyl] fluorene} and the like are preferable.
In particular, the unit (C1bi) derived from 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (BPEF) represented by the following formula is preferable.

The compounds for inducing these units (C1bi) can be used alone or in combination of two or more.
Unit (C1b-i) inducing compounds, obtained by reacting a 9,9-bis (hydroxyphenyl) fluorenes, compounds corresponding to the groups R ₃ and R ₄ (alkylene oxide, haloalkanol, etc.) and Be done. For example, 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene can be obtained by adding ethylene oxide to 9,9-bis (4-hydroxyphenyl) fluorene. 9,9-bis [4- (3-hydroxypropoxy) phenyl] fluorene can be obtained, for example, by reacting 9,9-bis [4-hydroxyphenyl] fluorene with 3-chloropropanol under alkaline conditions. Be done. In addition, 9,9-bis (hydroxyphenyl) fluorene can be obtained by reacting fluorenone (9-fluorenone or the like) with the corresponding phenol. 9,9-Bis (4-hydroxyphenyl) fluorene can be obtained, for example, by reacting phenol with 9-fluorenone.

Further, as the unit (C), a carbonate unit represented by the following formula (C2) is also preferably used.

In the above formula (C2), R ₇ and R ₈ are independently directly bonded and substituted with an alkylene group having 1 to 10 carbon atoms and an arylene group having 4 to 10 carbon atoms which may be substituted. , Or an aralkylene group having 6 to 10 carbon atoms which may be substituted, an alkylene group having 1 to 10 carbon atoms which may be substituted, an arylene group having 4 to 10 carbon atoms which may be substituted, and a substituted moiety. Two or more groups selected from the group consisting of aralkylene groups having 6 to 10 carbon atoms may be linked by an oxygen atom, an optionally substituted sulfur atom, an optionally substituted nitrogen atom or a carbonyl group. R ₉ is a directly bonded, optionally substituted alkylene group having 1 to 10 carbon atoms, optionally substituted arylene group having 4 to 10 carbon atoms, or optionally substituted. It is an aralkylene group having 6 to 10 carbon atoms, and R _{10 to} R ₁₁ are independently hydrogen atoms, an alkyl group having 1 to 10 carbon atoms which may be substituted, and 4 to 10 carbon atoms which may be substituted. An aryl group of 10, an acyl group having 1 to 10 carbon atoms which may be substituted, an alkoxy group having 1 to 10 carbon atoms which may be substituted, and an aryloxy group having 1 to 10 carbon atoms which may be substituted. , An amino group which may be substituted, a sulfur atom having a substituent, a halogen atom, a nitro group, or a cyano group. u and v independently indicate an integer of 1 to 4, and w indicates an integer value of 1 to 5. )

Specific examples of the compound that induces the above formula (C2) include 9,9'-di (hydroxymethyl) -9,9'-bifluorenyl, bis (9-hydroxymethylfluoren-9-yl) methane, 1,2. -Bis (9-hydroxymethylfluoren-9-yl) ethane, bis [9- (3-hydroxypropyl) -fluoren-9-yl] methane, bis {9- [2- (2-hydroxyethoxy) carbonyl ethyl] Fluolene-9-yl} methane, 9,9-bis [(9-hydroxymethylfluoren-9-yl) -methyl] fluorene, 1,2-bis [9- (3-hydroxypropyl) -fluoren-9-yl) ] Ethane, α, α'-bis- (9-hydroxymethylfluoren-9-yl) -1,4-xylene, 1,2-bis (9-hydroxymethylfluoren-9-yl) butane, 1-bis ( 9-Hydroxymethylfluoren-9-yl) ethane, 1,2-bis (9-hydroxyfluoren-9-yl) ethane, bis-{[4- (2-hydroxyethoxy) phenyl] fluoren-9-yl} ethane Is preferable.

Further, as the unit (C), an ester unit represented by the following formula (C3) is also preferably used. In this case, it becomes polyester carbonate.

In the above formula (C3), R _{7 to} R ₁₁ , u and v are synonymous with the above formula (C2), and X indicates an aliphatic group or an alicyclic group].
Specific examples of the compound that induces the above general formula (C3) include bis [9- (2-ethoxycarbonylethyl) fluorene-9-yl] methane and 1,2-bis [9- (2-ethoxycarbonylethyl). Fluoren-9-yl] ethane, 1,2-bis [9- (2-methoxycarbonylpropyl) fluoren-9-yl] ethane, bis [9- (2-methoxycarbonylethyl) fluoren-9-yl] methane, Bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] methane and 1,2-bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] ethane are preferred.

(composition)
The polycarbonate resin used in the present invention contains a unit (A) and a unit (B) as main repeating units, and their molar ratios (A / B) are 5/95 to 95/5. When the molar ratio (A / B) is 5/95 to 95/5, the heat resistance is high, which is preferable. The molar ratio (A / B) of the unit (A) to the unit (B) is preferably 5/95 to 85/15, more preferably 8/92 to 80/20. In the range of this composition, reverse wavelength dispersibility is preferable. It can also include the unit (C). The molar ratio (A + B / C) is preferably 30/70 to 80/20. The molar ratio can be measured and calculated by proton NMR of JNM-AL400 manufactured by JEOL Ltd.
The main repeating unit is such that the total of the units (A) and the units (B) is preferably 30 mol% or more, more preferably 50 mol% or more, still more preferably 60 mol% or more based on all the repeating units. ..

(Other units)
Examples of the diol compound that induces other copolymerization constituent units include aromatic dihydroxy compounds, α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene (bisphenol M), 9,9-bis (bisphenol M). 4-Hydroxy-3-methylphenyl) fluorene, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 4,4'- Dihydroxy-3,3'-dimethyldiphenyl sulfide, bisphenol A, 2,2-bis (4-hydroxy-3-methylphenyl) propane (bisphenol C), 2,2-bis (4-hydroxyphenyl) -1,1 , 1,3,3,3-hexafluoropropane (bisphenol AF), 1,1-bis (4-hydroxyphenyl) decane and the like.
In addition, a part of polyester carbonate can be obtained by copolymerizing an acid component such as terephthalic acid.

(Specific viscosity: η _SP )
The specific viscosity (η _SP ) of the polycarbonate resin used in the present invention is 0.25 to 0.45. When the specific viscosity is 0.25 to 0.45, the strength and moldability are good. The specific viscosity (η _SP ) is preferably 0.25 to 0.40, more preferably 0.30 to 0.35.
If the specific viscosity of the polycarbonate resin of the present invention is less than 0.2, the strength of the injection-molded molded piece is lowered, while if it is more than 0.45, the molding processability at the time of injection molding is lowered.
The specific viscosity referred to in the present invention is determined from a solution prepared by dissolving 0.7 g of polycarbonate resin in 100 ml of methylene chloride at 20 ° C. using an Ostwald viscometer.
Specific viscosity (η _SP ) = (t-t ₀ ) / t ₀
[T ₀ is the number of seconds for methylene chloride to fall, t is the number of seconds for the sample solution to fall]

The specific specific viscosity can be measured, for example, as follows. First, the polycarbonate resin is dissolved in 20 to 30 times the weight of methylene chloride, and the soluble component is collected by Celite filtration, and then the solution is removed and sufficiently dried to obtain a solid of methylene chloride soluble component. The specific viscosity at 20 ° C. from a solution of 0.7 g of such a solid in 100 ml of methylene chloride is determined using an Ostwald viscometer.

<Glass transition temperature: Tg>
The glass transition temperature (Tg) of the polycarbonate resin used in the optical film of the present invention is preferably 70 to 180 ° C, more preferably 130 to 175 ° C, still more preferably 135 to 175 ° C, and particularly preferably 140 to 170 ° C. Is the range of. If the glass transition temperature (Tg) is lower than 70 ° C., the heat resistance stability is inferior, and the phase difference value may change with time to affect the display quality. Further, if the glass transition temperature (Tg) is higher than 180 ° C., the viscosity may be too high and it may be difficult to form a melt film. The glass transition temperature (Tg) is measured at a heating rate of 20 ° C./min using a 2910 type DSC manufactured by TA Instruments Japan Co., Ltd.

<Photoelastic constant>
The photoelastic constant of the polycarbonate resin used in the optical film of the present invention is preferably 40 × 10 ^-12 Pa ^-1 or less, more preferably 30 × 10 ^-12 Pa ^-1 or less, still more preferably 25 × 10 ^-12. It is Pa ^-1 or less, particularly preferably 20 × 10 ^-12 Pa ^-1 or less. When the absolute value is larger than 40 × 10 ^-12 Pa- ¹ , birefringence due to stress is large, and light leakage is likely to occur when used as a retardation film. The photoelastic constant is measured by cutting out a test piece having a length of 50 mm and a width of 10 mm from the film and using a Spectroscopy Meter M-220 manufactured by JASCO Corporation.

(Manufacturing method of polycarbonate resin)
The polycarbonate resin can be produced by melt-polymerizing a component containing a unit (A) and a monomer inducing the unit (B) and a carbonic acid diester.

Examples of the carbonic acid diester include esters such as an aryl group and an aralkyl group having 6 to 12 carbon atoms which may be substituted. Specific examples thereof include diphenyl carbonate, ditriel carbonate, bis (chlorophenyl) carbonate and bis (m-credyl) carbonate. Of these, diphenyl carbonate is particularly preferable.
The amount of diphenyl carbonate used is preferably 0.97 to 1.10 mol, more preferably 1.00 to 1.06 mol, based on 1 mol of the total monomer components.

Further, in the melt polymerization method, a polymerization catalyst can be used in order to increase the polymerization rate, and examples of such a polymerization catalyst include alkali metal compounds, alkaline earth metal compounds, nitrogen-containing compounds, and metal compounds.

As such a compound, organic acid salts, inorganic salts, oxides, hydroxides, hydrides, alkoxides, quaternary ammonium hydroxides and the like of alkali metals and alkaline earth metals are preferably used, and these compounds are used. It can be used alone or in combination.

Examples of alkali metal compounds include sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium hydrogencarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium acetate, potassium acetate, cesium acetate, lithium acetate, etc. Sodium stearate, potassium stearate, cesium stearate, lithium stearate, sodium boron hydride, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, phosphorus Examples thereof include 2 lithium hydrogen acid, 2 sodium phenyl phosphate, 2 sodium salt of bisphenol A, 2 potassium salt, 2 cesium salt, 2 lithium salt, sodium phenol salt, potassium salt, cesium salt, lithium salt and the like.

As alkaline earth metal compounds, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, magnesium diacetate, calcium diacetate, strontium diacetate, diacetate Barium and the like can be mentioned.

Examples of the nitrogen-containing compound include quaternary ammonium hydroxides having alkyl and aryl groups such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and trimethylbenzylammonium hydroxide. Can be mentioned. Examples thereof include tertiary amines such as triethylamine, dimethylbenzylamine and triphenylamine, and imidazoles such as 2-methylimidazole, 2-phenylimidazole and benzimidazole. Examples thereof include bases or basic salts such as ammonia, tetramethylammonium borohydride, tetrabutylammonium borohydride, tetrabutylammonium tetraphenylborate and tetraphenylammonium tetraphenylborate. Examples of the metal compound include zinc aluminum compounds, germanium compounds, organotin compounds, antimony compounds, manganese compounds, titanium compounds, zirconium compounds and the like. These compounds may be used alone or in combination of two or more.

The amount of these polymerization catalysts used is preferably 1 × 10 ^-9 to 1 × 10 ⁻² equivalents, preferably 1 × 10 ^-8 to 1 × 10 ⁻⁵ equivalents, and more preferably 1 × 10 to 1 mol of the monomer component. It is selected in the range of ^10-7 to 1 × 10 ^-3 equivalents.

The melt polycondensation reaction is carried out by distilling out a monohydroxy compound produced by stirring while heating under an inert gas atmosphere and under reduced pressure, as is conventionally known.

The reaction temperature is usually in the range of 120 to 350 ° C., and in the latter stage of the reaction, the degree of pressure reduction of the system is increased to 10 to 0.1 Torr to facilitate distillation of the produced monohydroxy compound and complete the reaction. If necessary, a terminal terminator, an antioxidant and the like may be added.

It is also possible to add a catalytic deactivator in the latter stage of the reaction. As the catalyst deactivating agent to be used, known catalyst deactivating agents are effectively used, and among these, ammonium salts and phosphonium salts of sulfonic acids are preferable. Further, salts of dodecylbenzenesulfonic acid such as tetrabutylphosphonium salt of dodecylbenzenesulfonic acid and salts of paratoluenesulfonic acid such as tetrabutylammonium salt of paratoluenesulfonic acid are preferable.

As esters of sulfonic acid, methyl benzenesulfonic acid, ethyl benzenesulfonate, butyl benzenesulfonate, octyl benzenesulfonic acid, phenylbenzenesulfonic acid, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butyl paratoluenesulfonate, Octyl paratoluenesulfonate, phenyl paratoluenesulfonate and the like are preferably used. Among them, dodecylbenzenesulfonic acid tetrabutylphosphonium salt is most preferably used. When at least one polymerization catalyst selected from alkali metal compounds and / or alkaline earth metal compounds is used, the amount of these catalyst deactivators used is preferably 0.5 to 50 mol per mol of the catalyst. It can be used in proportions, more preferably 0.5 to 10 mol, and even more preferably 0.8 to 5 mol.

In addition, heat stabilizers, plasticizers, light stabilizers, polymerized metal inactivating agents, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, ultraviolet absorbers, mold release agents, etc. Additives can be blended.

<Optical film>
The optical film of the present invention will be described. This optical film is a film used for optical applications. Specific examples thereof include a retardation film, a placel substrate film, a polarizing plate protective film, an antireflection film, a brightness increasing film, an optical disk protective film, and a diffusion film. In particular, a retardation film, a polarizing plate protective film, and an antireflection film are preferable.

Examples of the method for producing the optical film include known methods such as a solution casting method, a melt extrusion method, a heat pressing method, and a calendar method. As a method for producing the optical film of the present invention, a solution casting method and a melt extrusion method are preferable, and a melt extrusion method is particularly preferable from the viewpoint of productivity.

In the melt extrusion method, a method of extruding the resin using a T-die and sending it to a cooling roll is preferably used. The temperature at this time is determined from the molecular weight, Tg, melt flow characteristics, etc. of the polycarbonate copolymer, but is in the range of 180 to 350 ° C., more preferably in the range of 200 ° C. to 320 ° C. If the temperature is lower than 180 ° C., the viscosity becomes high and the orientation and stress strain of the polymer tend to remain, which is not preferable. Further, if the temperature is higher than 350 ° C., problems such as heat deterioration, coloring, and die line (streak) from the T die are likely to occur.

Further, since the polycarbonate resin used in the present invention has good solubility in an organic solvent, a solution casting method can also be applied. In the case of the solution casting method, methylene chloride, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, dioxolane, dioxane and the like are preferably used as the solvent. The amount of residual solvent in the film used in the solution casting method is preferably 2% by weight or less, more preferably 1% by weight or less. If it exceeds 2% by weight, if the residual solvent is large, the glass transition temperature of the film is significantly lowered, which is not preferable in terms of heat resistance.

The thickness of the unstretched optical film of the present invention is preferably in the range of 20 to 400 μm, more preferably in the range of 20 to 300 μm. When such a film is further stretched to obtain a retardation film, it may be appropriately determined within the above range in consideration of the desired retardation value and thickness of the optical film.
The unstretched optical film thus obtained is stretch-oriented to become a retardation film. As the stretching method, known methods such as longitudinal uniaxial stretching, horizontal uniaxial stretching using a tenter, simultaneous biaxial stretching combining them, and sequential biaxial stretching can be used. Further, it is preferable to perform it continuously from the viewpoint of productivity, but it may be performed in a batch system. The stretching temperature is preferably in the range of (Tg-20 ° C.) to (Tg + 50 ° C.), more preferably (Tg-10 ° C.) to (Tg + 30 ° C.) with respect to the glass transition temperature (Tg) of the polycarbonate copolymer. The range. Within this temperature range, the molecular motion of the polymer is appropriate, relaxation due to stretching is unlikely to occur, orientation suppression is easy, and a desired Re value can be easily obtained, which is preferable.

The draw ratio is determined by the target phase difference value, but is 1.05 to 5 times, more preferably 1.1 to 4 times, respectively, in the vertical direction and the horizontal direction. This stretching may be performed in one stage or in multiple stages. The Tg when the film obtained by the solution casting method is stretched refers to the glass transition temperature containing a trace amount of solvent in the film.

(Thickness, etc.)
The thickness of the optical film of the present invention is preferably in the range of 20 to 200 μm, more preferably 20 to 150 μm. Within this range, it is easy to obtain a desired retardation value by stretching, and film formation is also easy and preferable.

The optical film of the present invention has a low photoelastic constant of the polycarbonate resin constituting the optical film. Therefore, the change in the phase difference with respect to the stress is small, and the liquid crystal display device provided with the retardation film has excellent display stability.

Further, the optical film of the present invention has high transparency. The total light transmittance of the optical film of the present invention having a thickness of 100 μm is preferably 85% or more, more preferably 88% or more. The haze value of the optical film of the present invention is preferably 5% or less, more preferably 3% or less.

(Wavelength dispersibility)
By stretching an unstretched film made of the polycarbonate resin used in the present invention, in the visible light region having a wavelength of 400 to 800 nm, the inverse wavelength dispersibility becomes smaller as the in-plane phase difference becomes shorter. An optical film can be obtained. It is desirable that the stretched retardation film satisfies the conditions of the following formulas (1) and (2).
0.60 <R (450) / R (550) <1.00 (1)
1.01 <R (650) / R (550) <1.40 (2)
Preferably, the conditions of the following formulas (1-1) and (2-1) are satisfied.
0.65 <R (450) / R (550) <0.92 (1-1)
1.02 <R (650) / R (550) <1.35 (2-1)
More preferably, the conditions of the following formulas (1-2) and (2-2) are satisfied.
0.70 <R (450) / R (550) <0.90 (1-2)
1.03 <R (650) / R (550) <1.30 (2-2)
More preferably, the conditions of the following formulas (1-3) and (2-3) are satisfied.
0.70 <R (450) / R (550) <0.89 (1-3)
1.03 <R (650) / R (550) <1.20 (2-3)
Particularly preferably, the conditions of the following formulas (1-4) and (2-4) are satisfied.
0.70 <R (450) / R (550) <0.88 (1-4)
1.03 <R (650) / R (550) <1.10 (2-4)
Most preferably, the conditions of the following formulas (1-5) and (2-5) are satisfied.
0.70 <R (450) / R (550) <0.87 (1-5)
1.03 <R (650) / R (550) <1.10 (2-5)

Here, the in-plane phase difference value R is defined by the following equation, and is a characteristic showing a phase lag between the X direction of light transmitted in the direction perpendicular to the film and the Y direction perpendicular to it.
R = (n _{x −} n _y ) × d
However, n _x is the refractive index in the main stretching direction in the film plane, _ny is the refractive index in the direction perpendicular to the main stretching direction in the film plane, and d is the thickness of the film. Here, the main stretching direction means the stretching direction in the case of uniaxial stretching, and the stretching direction in the case of biaxial stretching so as to increase the degree of orientation, and the chemical structure of the polymer main chain. Refers to the orientation direction.

Further, the in-plane retardation value R (550) of the optical film at a wavelength of 550 nm is preferably R (550) ≥ 50 nm. One optical film can be used as a wideband λ / 4 plate or λ / 2 plate without being laminated. Further, in such an application, it is desirable that 100 nm ≦ R (550) ≦ 180 nm for the λ / 4 plate and 220 nm ≦ R (550) ≦ 330 nm for the λ / 2 plate.

The wavelength dispersibility of the optical film is measured using a Spectrolipsometer M-220 manufactured by JASCO Corporation.
The optical film of the present invention can be particularly preferably used as a retardation film. The present invention includes an image display device (liquid crystal display device or organic EL display device) provided with the above retardation film. In the present invention, a circularly polarizing film composed of the retardation film and a polarizing layer can be used as an antireflection film. Further, the retardation film can be suitably used as a polarizing plate protective film or an optical compensation film of an image display device.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. In the examples, "part" means "part by weight". The resin used and the evaluation method used in the examples are as follows.

1. 1. Polymer composition ratio (NMR)
The polymer composition ratio was calculated by measuring with proton NMR of JNM-AL400 manufactured by JEOL Ltd.

2. 2. It was determined using an Ostwald viscometer from a solution prepared by dissolving 0.7 g of a polycarbonate resin in 100 ml of methylene chloride at a specific viscosity of 20 ° C.
Specific viscosity (η _SP ) = (t-t ₀ ) / t ₀
[T ₀ is the number of seconds for methylene chloride to fall, t is the number of seconds for the sample solution to fall]

3. 3. Tg (glass transition temperature)
Using a 2910 type DSC manufactured by TA Instruments Japan Co., Ltd., the measurement was carried out in a nitrogen atmosphere at a heating rate of 20 ° C./min.

4. Photoelastic constant A test piece having a length of 50 mm and a width of 10 mm was cut out from the film, and the photoelastic constant was measured using a Spectrolipsometer M-220 manufactured by JASCO Corporation.

5. Phase difference and wavelength dispersibility A test piece having a length of 100 mm and a width of 70 mm was cut out from the film and vertically stretched 2.0 times at a stretching temperature of Tg + 10 ° C. The phase difference wavelength dispersibility was measured using −220.

6. Evaluation of thermal unevenness A linear polarizing plate is prepared in which a polarizing element film in which iodine is adsorbed and oriented in polyvinyl alcohol is sandwiched between two triacetyl cellulose films, and an acrylic pressure-sensitive adhesive layer is provided on one side thereof. did. The stretched film prepared in the examples was subjected to corona discharge treatment under the condition of an integrated irradiation amount of 1500 J, and the corona discharge treated surface was laminated to the linear polarizing plate at an angle of 45 ° on the acrylic pressure-sensitive adhesive layer side. Two of the above polarizing plates were prepared and bonded to non-alkali glass (manufactured by Corning Japan, trade name: EAGLE2000) via an adhesive as shown in FIG. Immediately after storing the constructed circularly polarizing plate at 90 ° C. for 240 minutes, the light leakage of the transmitted light when the backlight is applied is visually evaluated. If there is no light leakage, ○, if there is light leakage as a whole, It was marked with x.

[Example 1]
<Manufacturing of polycarbonate copolymer>
6,6'-dihydroxy-3,3,3', 3'-tetramethyl-1,1'-spirobiindan (hereinafter sometimes abbreviated as "SBI") 72.5 parts, 3,9-bis (2) -Hydroxy-1,1-dimethylethyl) -2,4,8,10-Tetraoxaspiro (5.5) Undecane (hereinafter abbreviated as SPG) 47.7 parts, diphenyl carbonate 85.7 parts and tetramethyl as a catalyst 1.8 × ^10-2 parts of ammonium hydroxide and 1.6 × 10 ^-4 parts of sodium hydroxide were heated to 180 ° C. in a nitrogen atmosphere to melt them. Then, the degree of decompression was adjusted to 13.4 kPa over 30 minutes. Then, the temperature was raised to 260 ° C. at a rate of 20 ° C./hr, held at that temperature for 10 minutes, and then the degree of decompression was adjusted to 133 Pa or less over 1 hour. The reaction was carried out under stirring for a total of 6 hours.
After completion of the reaction, 4 times the molar amount of dodecylbenzenesulfonic acid tetrabutylphosphonium salt was added to deactivate the catalyst, then discharged from the bottom of the reaction tank under nitrogen pressure, cooled in a water tank, and cut with a pelletizer. To obtain pellets.

<Manufacturing of optical film>
Next, a T-die having a width of 150 mm and a lip width of 500 μm and a film take-up device were attached to a 15φ twin-screw extruder manufactured by Technobel Co., Ltd., and the obtained polycarbonate copolymer was melt-extruded at 290 ° C. to form a film. A transparent extruded film was obtained. The evaluation results are shown in Table 1.

[Example 2]
<Manufacturing of polycarbonate copolymer resin>
Exactly the same procedure as in Example 1 was carried out except that 60.4 parts of SBI and 59.6 parts of SPG were used to obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was prepared in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Example 3]
<Manufacturing of polycarbonate copolymer resin>
An operation exactly the same as in Example 1 was carried out except that 48.3 parts of SBI and 71.5 parts of SPG were used to obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was prepared in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Example 4]
<Manufacturing of polycarbonate copolymer resin>
Exactly the same as in Example 1 except that 17.2 parts of 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (hereinafter abbreviated as BPEF), 48.3 parts of SBI, and 59.6 parts of SPG were used. The operation was carried out to obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was prepared in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Example 5]
<Manufacturing of polycarbonate copolymer resin>
The operation is exactly the same as in Example 1 except that 44.5 parts of 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (hereinafter abbreviated as BCF), 12.1 parts of SBI, and 71.5 parts of SPG are used. To obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was prepared in the same manner as in Example 1. The evaluation results are shown in Table 1.

[ Reference example 6]
<Manufacturing of polycarbonate copolymer resin>
Exactly the same procedure as in Example 1 was carried out except that 28.6 parts of isosorbide (hereinafter abbreviated as ISS), 24.2 parts of SBI and 44.5 parts of BPEF were used to obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was prepared in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Reference Example 7]
<Manufacturing of polycarbonate copolymer resin>
Exactly the same operation as in Example 1 was carried out except that 80 parts of spirobichroman (hereinafter abbreviated as SBC) and 22.9 parts of SPG were used to obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was prepared in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 1]
<Manufacturing of polycarbonate copolymer resin>
Exactly the same operation as in Example 1 was carried out except that 86.0 parts of BPEF and 28.6 parts of ISS were used to obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was prepared in the same manner as in Example 1. The evaluation results are shown in Table 1. As a result of thermal unevenness evaluation, color loss due to thermal unevenness due to the photoelastic coefficient occurred.

[Comparative Example 2]
<Manufacturing of polycarbonate copolymer resin>
An operation exactly the same as in Example 1 was carried out except that 50.4 parts of BCF and 37.8 parts of ISS were used to obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was produced in the same manner as in Example 1, but because the Tg was too high, the resin was decomposed and foaming occurred, and the quality as an optical film was not satisfied.

[Comparative Example 3]
<Manufacturing of polycarbonate copolymer resin>
Exactly the same operation as in Example 1 was carried out except that 86 parts of BPEF and 59.6 parts of SPG were used to obtain an aliphatic aromatic polycarbonate copolymer.
<Manufacturing of optical film>
Next, a film was prepared in the same manner as in Example 1. The evaluation results are shown in Table 1. As a result of thermal unevenness evaluation, color loss due to thermal unevenness occurred due to low heat resistance.

The optical film of the present invention is useful as an optical film for liquid crystal display devices, organic EL displays, and the like.

1. 1. Polarizing plate 2. Stretched film 3. Inorganic glass 4. Stretched film 5. Polarizer

Claims (9)

The carbonate unit (A) derived from 6,6'-dihydroxy-3,3,3', 3'-tetramethyl-1,1'-spirobiindane and 3,9-bis (2-hydroxy-1,1) -Dichloromethane) -2,4,8,10-Tetraoxaspiro (5.5) Contains carbonate units (B) derived from undecane (but does not include carbonate units derived from isosorbide) , units ( The molar ratio (A / B) of A) to the unit (B) is 5/95 to 50/50 or 60/40 to 95/5 , and the specific viscosity measured with a methylene chloride solution at 20 ° C. is 0. Polycarbonate resin of 20 to 0.45. The polycarbonate resin according to claim 1, wherein the glass transition temperature of the polycarbonate resin is 70 ° C to 180 ° C. The polycarbonate resin according to claim 1, wherein the photoelastic constant of the polycarbonate resin is 40 × 10 ^-12 Pa ^-1 or less. The polycarbonate resin according to claim 1, further comprising a carbonate unit (C) derived from a dihydroxy compound having a fluorene skeleton. An optical film formed from the polycarbonate resin according to any one of claims 1 to 4. The optical film according to claim 5, wherein the optical film is formed by a melt extrusion method. The optical film according to claim 5, wherein the optical film is a retardation film formed by stretching an unstretched film. The optical film according to claim 7, wherein the in-plane retardation values R (450), R (550), and R (650) at wavelengths of 450 nm, 550 nm, and 650 nm satisfy the following formulas (1) and (2). ..
0.60 ≤ R (450) / R (550) ≤ 1.00 (1)
1.01 ≤ R (650) / R (550) ≤ 1.40 (2) A liquid crystal display device or an organic EL display device including the optical film according to claim 8.

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