JP5079150B2 - Retardation film - Google Patents

Description

The present invention relates to a retardation film having a desired wavelength dispersion characteristics, the elastic constant is low, high heat resistance, a retardation film having excellent melt processability.
Such a retardation film is suitably used for, for example, a liquid crystal display device, an optical pickup used in a recording device, an optical device such as an optical recording medium, a light emitting element, an optical arithmetic element, an optical communication element, and a touch panel.

  The optical film is used as a retardation film and a protective film for a polarizing plate. The retardation film is used in a liquid crystal display device or the like, and has functions such as color compensation, viewing angle expansion, and antireflection. As the retardation film, a λ / 4 plate and a λ / 2 plate are known, and polycarbonate, polyethersulfone, polysulfone, and the like are used as the material thereof. The λ / 4 plate and λ / 2 plate made of these materials have the property that the phase difference increases as the wavelength becomes shorter. For this reason, 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 for controlling the wavelength in a wide band, a method is known in which two or more birefringent films having different wavelength dependences of retardation are laminated at a specific angle (Patent Document 1). This method requires a step of bonding a plurality of retardation films, a step of adjusting the bonding angle, and the like, and has a problem in productivity. Moreover, since the thickness of the whole retardation film becomes large, there also exists a problem that light transmittance falls and it becomes dark.

  In recent years, there has been proposed a method of controlling the wavelength in a wide band with a single film without performing such lamination (Patent Document 2). This is a method using a polycarbonate copolymer comprising a unit having a positive refractive index anisotropy and a unit having a negative refractive index anisotropy. However, since this polycarbonate copolymer contains units derived from fluorene-based bisphenol, there is a problem that the melting temperature is high, and a gel product due to decomposition is easily generated during melt processing. Further, the glass transition temperature (Tg) is high, a high temperature is required for stretching the film, and special processing equipment different from the conventional one is required. In addition, the photoelastic constant is high, the birefringence due to stress is large, and there is a problem that light leakage occurs when used as a retardation film.

  On the other hand, a polycarbonate copolymer having a low photoelastic constant using an aliphatic diol for use in an optical fiber, an optical disk or the like has already been proposed (Patent Document 3). However, this document does not discuss the stretching of the film and the wavelength dispersibility. Further, the photoelastic constant of the polycarbonate copolymer described in this document needs to be further reduced when used as a protective film for a retardation film or a polarizing plate.

  In addition, a retardation film having a low photoelastic constant using a polycarbonate copolymer containing a fluorene ring and an isosorbide component has been reported (Patent Document 4). Since this polycarbonate copolymer is a ternary copolymer, in order to control the wavelength dispersion, it is necessary to precisely control the composition ratio of the three components, and it is not easy to produce stably. . In addition, since the thermal stability is low, there is a drawback that the molecular weight tends to decrease during melt processing.

  A retardation film made of a polycarbonate copolymer containing a fluorene-based bisphenol skeleton has also been proposed (Patent Documents 5 and 6). A polarizing plate protective film made of a polycarbonate copolymer containing a fluorene-based bisphenol skeleton has also been proposed (Patent Document 7). However, in any case, the glass transition temperature (Tg) is high, a high temperature is required for stretching the film, and special processing equipment different from the conventional one is required. In addition, the photoelastic constant is high, the birefringence due to stress is large, and there is a problem that light leakage occurs when used as a retardation film.

Japanese Patent Laid-Open No. 2-120804 Japanese Patent No. 3325560 JP 2004-67990 A International Publication No. 06/041190 Pamphlet International Publication No. 01/009649 Pamphlet JP 2006-323254 A Japanese Patent No. 3995387

An object of the present invention is to provide a retardation film made of a polycarbonate copolymer resin having desired wavelength dispersion characteristics, low photoelasticity, and excellent melt processability.

As a result of intensive studies, the present inventor has shown that a retardation film made of a polycarbonate copolymer of a diol having a fluorene structure in a side chain and a specific aliphatic diol has a reverse wavelength dispersion property that becomes smaller as the retardation becomes shorter. It was found that the photoelastic constant was low and the melt processability was excellent, and the present invention was achieved.

で表される単位（Ａ４）および下記式

で表される単位（Ｂ１）を含むポリカーボネート共重合体からなり、下記（ｉ）を満足する位相差フィルム。
（ｉ）単位（Ａ４）と単位（Ｂ１）とのモル比（Ａ４／Ｂ１）が４０／６０以上６０／４０以下であり、下記式（１）〜（３）を満たす
Ｒ（４５０）＜Ｒ（５５０）＜Ｒ（６５０） （１）
０．６＜Ｒ（４５０）／Ｒ（５５０）＜０．９２ （２）
１．０１＜Ｒ（６５０）／Ｒ（５５０）＜１．４０ （３）
（但し、Ｒ（４５０）、Ｒ（５５０）およびＲ（６５０）は夫々、波長４５０ｎｍ、５５０ｎｍ、６５０ｎｍにおけるフィルム面内の位相差値を示す。）
２．光弾性定数の絶対値が３０×１０^−１２Ｐａ^−１以下である前項１記載の位相差フィルム。
３．位相差フィルムは、縦一軸延伸、横一軸延伸あるいは二軸延伸の方法により、（イ）延伸温度がポリカーボネート共重合体のガラス転移温度（Ｔｇ）に対して（Ｔｇ−２０℃）〜（Ｔｇ＋５０℃）の範囲、（ロ）延伸倍率が１．０５〜５倍、の条件で延伸されたフィルムである、前項１記載の位相差フィルム。
４．有機ＥＬディスプレイ用の位相差フィルムである、前項１記載の位相差フィルム。
５．前項１記載の位相差フィルムを具備した液晶表示装置。
６．前項１記載の位相差フィルムを具備した有機ＥＬディスプレイ。
７．前項１記載の位相差フィルムと偏光層とからなる円偏光フィルム。
８．前項７の円偏光フィルムを反射防止フィルムとして用いた表示素子。
９．反射防止フィルムは、有機ＥＬディスプレイ用反射防止フィルムである前項８記載の表示素子。
が提供される。 That is, according to the present invention,
1. Following formula

The unit represented by ( A4 ) and the following formula

A retardation film units (B 1) consists of polycarbonate copolymer comprising, it satisfies the following (i) represented in.
(I) Unit (A4) and the unit (B 1) the molar ratio of (A4 / B 1) is 40/60 or more to 60/40 or less, R satisfying the following formula (1) to (3) (450) <R (550) <R (650) (1)
0.6 <R (450) / R (550) < 0.92 (2)
1.01 <R (650) / R (550) < 1.40 (3)
(However, R (450), R (550), and R (650) represent retardation values in the film plane at wavelengths of 450 nm, 550 nm, and 650 nm, respectively).
2 . 2. The retardation film as described in 1 above, wherein the absolute value of the photoelastic constant is 30 × 10 ⁻¹² Pa ⁻¹ or less.
3. The retardation film is obtained by a method of longitudinal uniaxial stretching, lateral uniaxial stretching or biaxial stretching. (A) The stretching temperature is (Tg-20 ° C) to (Tg-20 ° C) to the glass transition temperature (Tg) of the polycarbonate copolymer. The retardation film as described in 1 above, which is a film stretched under the conditions of (b) and (b) a draw ratio of 1.05 to 5 times.
4). 2. The retardation film as described in 1 above, which is a retardation film for an organic EL display.
5 . A liquid crystal display device comprising the retardation film according to item 1 .
6). An organic EL display comprising the retardation film as described in 1 above .
7 . A circularly polarizing film comprising the retardation film according to item 1 and a polarizing layer.
8 . A display element using the circularly polarizing film of item 7 as an antireflection film.
9. 9. The display element according to 8 above, wherein the antireflection film is an antireflection film for an organic EL display.
Is provided.

  The retardation film of the present invention is composed of a polycarbonate copolymer resin having a desired wavelength dispersion characteristic, a low photoelastic constant, a high degree of transparency, and an excellent processability. And can be broadened with a single sheet, and is extremely useful as a retardation film for liquid crystal display devices and organic EL displays.

Hereinafter, the present invention will be described in detail.
<Polycarbonate copolymer>
The retardation film of the present invention, made of a polycarbonate copolymer containing a unit (A4) and the unit (B 1).

単位（Ａ４）は、９，９−ビス［４−（２−ヒドロキシエトキシ）フェニル］フルオレン（ＢＰＥＦ）から誘導される。
９，９−ビス［４−（２−ヒドロキシエトキシ）フェニル］フルオレンは、９，９−ビス（４−ヒドロキシフェニル）フルオレンにエチレンオキサイドを付加することにより得られる。９，９−ビス（４−ヒドロキシフェニル）フルオレンは、例えば、フェノールと９−フルオレノンとの反応によって得ることができる。 (Unit (A 4))
The unit (A 4 ) is represented by the following formula.

Unit (A4) is Ru are derived from 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (BPEF).
9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene is obtained by adding ethylene oxide to 9,9-bis (4-hydroxyphenyl) fluorene . 9, 9-bis (4-hydroxyphenyl) fluorene can be obtained, for example, by reaction of a phenol and 9-fluorenone.

上記式で表される繰り返し単位は、エーテルジオール由来の単位であり、該エーテルジオールとして具体的には、イソソルビドである。 (Unit (B 1 ))
The unit (B 1 ) is represented by the following formula.

Repeating unit represented by the above formula is a unit derived from polyether diols, particularly as the ether diol, Lee Sosorubido.

Ether diols derived from sugars This is a material obtained from natural biomass is one of those called renewable resources. Isosorbide is obtained by hydrogenating D-glucose obtained from starch and then dehydrating it.

  In particular, the carbonate constituent unit is preferably a carbonate constituent unit derived from isosorbide (1,4,3,6-dianhydro-D-sorbitol). Isosorbide is an ether diol that can be easily made from starch, and can be obtained in abundant resources, and is superior in all ease of manufacture, properties, and versatility of use compared to isomannide and isoidide. .

(Composition ratio)
The molar ratio (A 4 / B 1 ) of the unit (A 4 ) to the unit (B 1 ) in the polycarbonate copolymer is 40/60 or more and 60/40 or less. When the molar ratio (A 4 / B 1 ) is less than 40/60 or exceeds 60/40, the wavelength dispersibility of the polycarbonate copolymer is not reverse dispersibility, and there is a problem in optical characteristics . Or the composition ratio is within 0.5 mol% the deviation of composition ratio after polymerization and charging ratio, it is preferably to be controlled to within 0.3 mol%. If it exceeds 0.5 mol%, the wavelength dispersibility changes greatly, which causes a problem in quality. The molar ratio (A 4 / B 1 ) is measured and calculated by proton NMR of JNM-AL400 manufactured by JEOL.

(Glass transition temperature: Tg)
The glass transition temperature (Tg) of the polycarbonate copolymer is preferably 140 to 200 ° C, more preferably 140 to 180 ° C. When the glass transition temperature (Tg) is lower than 140 ° C., the heat resistance stability is inferior, and the retardation value may change with time, which may affect the display quality. On the other hand, if the glass transition temperature (Tg) is higher than 200 ° C., the viscosity becomes too high during melt polymerization, which makes it difficult. The glass transition temperature (Tg) is measured at 29 ° C./min using a 2910 type DSC manufactured by TA Instruments Japan.

(Photoelastic constant)
The absolute value of the photoelastic constant of the polycarbonate copolymer is preferably 30 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 28 × 10 ⁻¹² Pa ⁻¹ or less, and even more preferably 25 × 10 ⁻¹² Pa ⁻¹ or less. It is. When the absolute value is larger than 30 × 10 ⁻¹² Pa ⁻¹ , birefringence due to stress is large, and light leakage occurs when used as a retardation film, which is not preferable. The photoelastic constant is measured using a Spectroellipometer M-220 manufactured by JASCO Corporation by cutting a test piece having a length of 50 mm and a width of 10 mm from the film.

(Production method)
The polycarbonate copolymer can be produced by melt polymerization of a full orange hydroxy component, an aliphatic diol component and a carbonic acid diester.
Examples of the carbonic acid diester include esters such as an aryl group having 6 to 12 carbon atoms and an aralkyl group which may be substituted. Specific examples include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, and bis (m-cresyl) carbonate. Of these, diphenyl carbonate is particularly preferred.
The amount of diphenyl carbonate used is preferably 0.97 to 1.10 mol, more preferably 1.00 to 1.06 mol, per 1 mol of the total of dihydroxy compounds.

In the melt polymerization method, a polymerization catalyst can be used to increase the polymerization rate. Examples of the polymerization catalyst include alkali metal compounds, alkaline earth metal compounds, nitrogen-containing compounds, and metal compounds.
As such compounds, 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. It can be used alone or in combination.

  Examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium acetate, potassium acetate, cesium acetate, lithium acetate, Sodium stearate, potassium stearate, cesium stearate, lithium stearate, sodium borohydride, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, phosphorus Examples thereof include dilithium oxyhydrogen, disodium phenylphosphate, disodium salt of bisphenol A, dipotassium salt, cesium salt, dilithium salt, sodium salt of phenol, potassium salt, cesium salt, and lithium salt.

  Alkaline earth metal compounds include magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, magnesium diacetate, calcium diacetate, strontium diacetate, diacetate Barium etc. are mentioned.

  Examples of nitrogen-containing compounds include quaternary ammonium hydroxides having alkyl, aryl groups, etc., such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and trimethylbenzylammonium hydroxide. Can be mentioned. Further, tertiary amines such as triethylamine, dimethylbenzylamine, and triphenylamine, and imidazoles such as 2-methylimidazole, 2-phenylimidazole, and benzimidazole can be used. Moreover, bases or basic salts such as ammonia, tetramethylammonium borohydride, tetrabutylammonium borohydride, tetrabutylammonium tetraphenylborate, tetraphenylammonium tetraphenylborate, and the like can be given. 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 equivalent, preferably 1 × 10 ⁻⁸ to 1 × 10 ⁻⁵ equivalent, more preferably 1 × with ^respect to 1 mol of the diol component. It is selected in the range of 10 ⁻⁷ to 1 × 10 ⁻³ equivalents.

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

  The reaction temperature is usually in the range of 120 to 350 ° C., and in the latter stage of the reaction, the monohydroxy compound formed by increasing the pressure reduction degree of the system to 10 to 0.1 Torr is facilitated to complete the reaction. You may add a terminal terminator, antioxidant, etc. as needed.

  In addition, a catalyst deactivator can be added at a later stage of the reaction. As the catalyst deactivator to be used, a known catalyst deactivator is effectively used. Among them, sulfonic acid ammonium salt and phosphonium salt are preferable. Furthermore, 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.

  Further, as esters of sulfonic acid, methyl benzenesulfonate, ethyl benzenesulfonate, butyl benzenesulfonate, octyl benzenesulfonate, phenyl benzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butyl paratoluenesulfonate, Octyl paratoluenesulfonate, phenyl paratoluenesulfonate and the like are preferably used. Among these, dodecylbenzenesulfonic acid tetrabutylphosphonium salt is most preferably used. The amount of the catalyst deactivator used is preferably 0.5 to 50 mol per mol of the catalyst when at least one polymerization catalyst selected from alkali metal compounds and / or alkaline earth metal compounds is used. It can be used in a proportion, more preferably in a proportion of 0.5 to 10 mol, still more preferably in a proportion of 0.8 to 5 mol.

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

<Optical film>
The optical film will be described. This optical film is a film used for optical applications. Specifically, a retardation film, a plastic substrate film, a polarizing plate protective film, an antireflection film, a brightness enhancement film, an optical disk protective film, a diffusion film, and the like can be given. In particular, a retardation film, a polarizing plate protective film, and an antireflection film are preferable.

Examples of the method for producing an optical film include known methods such as a solution casting method, a melt extrusion method, a hot pressing method, and a calendar method . Methods for producing light optical film, the melt extrusion method is preferred from the viewpoint of productivity.

  In the melt extrusion method, a method of extruding a resin using a T die and feeding 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 to 320 ° C. When the temperature is lower than 180 ° C., the viscosity is increased, and the orientation and stress strain of the polymer tend to remain, which is not preferable. On the other hand, when the temperature is higher than 350 ° C., problems such as thermal deterioration, coloring, and die line (stripe) from the T-die are likely to occur.

  Moreover, since the polycarbonate copolymer used by this invention has the favorable solubility with respect to an organic solvent, the solution cast method is also applicable. 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 remarkably lowered, which is not preferable from the viewpoint of heat resistance.

  As thickness of the unstretched optical film of this invention, the range of 30-400 micrometers is preferable, More preferably, it is the range of 40-300 micrometers. When such a film is further stretched to obtain a retardation film, it may be appropriately determined within the above range in consideration of a desired retardation value and thickness of the optical film.

  The unstretched optical film thus obtained is stretched and oriented to form a retardation film. As the stretching method, a known method such as longitudinal uniaxial stretching, lateral uniaxial stretching using a tenter or the like, or simultaneous biaxial stretching or sequential biaxial stretching in combination thereof can be used. Moreover, although it is preferable from a point of productivity to perform continuously, you may carry out by a batch type. 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. It is a range. This temperature range is preferable because the molecular motion of the polymer is appropriate, relaxation due to stretching is unlikely to occur, orientation is easily suppressed, and a desired in-plane retardation is easily obtained.

  Although the draw ratio is determined by the target retardation value, it is 1.05 to 5 times, more preferably 1.1 to 4 times in the vertical and horizontal directions, respectively. This stretching may be performed in a single stage or in multiple stages. In addition, said Tg in the case of extending | stretching the film obtained by the solution cast method means the glass transition temperature containing the trace amount solvent in this film.

(Wavelength dispersion)
The retardation film of the present invention is characterized in that in the visible light region having a wavelength of 400 to 800 nm, the retardation in the film plane becomes smaller as the wavelength becomes shorter. That is, the following formula (1)
R (450) <R (550) <R (650) (1)
Meet. However, R (450), R (550), and R (650) represent retardation values in the film plane at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
Here, the in-plane retardation value R is defined by the following equation, and is a characteristic that expresses a phase delay between the X direction of light transmitted through the film in the vertical direction and the vertical Y direction.
_{R = (n x -n y)} × d
However, n _x is a refractive index in a slow axis (highest refractive index axis) in the film plane, n _y is a refractive index of n _x and the vertical direction in the film plane, d is the thickness of the film is there.

(Thickness etc.)
The thickness of the retardation film of the present invention is preferably in the range of 20 to 200 μm, more preferably 20 to 150 μm. If it is this range, the desired phase difference value by extending | stretching will be easy to be obtained, and film forming is also easy and preferable.
The retardation film of the present invention has a low photoelastic constant of the polycarbonate copolymer constituting it. Therefore, the change of the phase difference with respect to the stress is small, and the liquid crystal display device provided with such a retardation film has excellent display stability.

The retardation film of the present invention has high transparency. The total light transmittance of the retardation 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 retardation film of the present invention is preferably 5% or less, more preferably 3% or less.
The present invention includes a liquid crystal display device provided with the retardation film. The present invention includes a circularly polarizing film comprising the retardation film of the present invention and a polarizing layer. The present invention includes a display element using the above circularly polarizing film as an antireflection film.

(Preferred embodiment)
The following film (II ) is mentioned as an aspect of the retardation film of the present invention.

(Film (II))
Film (II) has the following formulas (2) and (3)
0.6 <R (450) / R (550) < 0.92 (2)
1.01 <R (650) / R (550) < 1.40 (3)
It is the film which shows what is called reverse wavelength dispersion. The film (II) is suitably used for a retardation film such as a liquid crystal display device.

The film (II) more preferably satisfies the following conditions.
0.65 <R (450) / R (550) <0.92 (2- 1)
1.01 <R (650) / R (550) <1.30 (3- 1)
The film (II) particularly preferably satisfies the following conditions.
0.7 <R (450) / R (550) <0.91 (2- 2)
1.03 <R (650) / R (550) <1.20 (3- 2)

  The in-plane retardation value R (550) of the film (II) at a wavelength of 550 nm is preferably R (550)> 50 nm. The film (II) can be used as a wide band λ / 4 plate or λ / 2 plate without being laminated. In such applications, it is further desirable that 100 nm <R (550) <180 nm for a λ / 4 plate and 220 nm <R (550) <330 nm for a λ / 2 plate. For wavelength dispersion, a test piece having a length of 100 mm and a width of 70 mm was cut out from the film, and longitudinally stretched 2.0 times at a stretching temperature of Tg + 10 ° C., and the resulting film was used with Spectrophotometer M-220 manufactured by JASCO Corporation. Then measure.

で表される単位（Ａ４）および下記式

で表される単位（Ｂ１）を含み、単位（Ａ４）と単位（Ｂ１）とのモル比（Ａ４／Ｂ１）が４０／６０以上６０／４０以下の範囲であり、光弾性定数の絶対値３０×１０^−１２Ｐａ^−１以下であることが好ましく、２５×１０^−１２Ｐａ^−１以下であることがより好ましい。 The polycarbonate copolymer of film (II) has the following formula:

The unit (A 4 ) represented by

In represented by units (B 1) comprises a molar ratio (A 4 / B 1) range of 40/60 or more 60/40 following units (A 4) and the unit (B 1), photoelastic The absolute value of the constant is preferably 30 × 10 ⁻¹² Pa ⁻¹ or less, and more preferably 25 × 10 ⁻¹² Pa ⁻¹ or less.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. In the examples, “parts” means “parts by weight”. The resins used and the evaluation methods used in the examples are as follows.
1. Photoelastic constant measurement 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 Spectroellipometer M-220 manufactured by JASCO Corporation.
2. Measurement of 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 longitudinally stretched 2.0 times at a stretching temperature of Tg + 10 ° C., and the resulting film was made by Spectroscopicmeter M-220 manufactured by JASCO Corporation. Was used to measure the retardation wavelength dispersion.
3. Tg (glass transition temperature) measurement A 2910 type DSC manufactured by TA Instruments Japan Co., Ltd. was used, and the temperature was measured at a heating rate of 20 ° C./min in a nitrogen atmosphere.
4). Polymer composition ratio (NMR)
Measurement was performed by proton NMR of JNM-AL400 manufactured by JEOL Ltd., and the polymer composition ratio was calculated.
5. Viscosity average molecular weight The viscosity average molecular weight was measured by dissolving 0.7 g of polycarbonate resin in 100 mL of methylene chloride and using a 20 ° C solution. The determined specific viscosity (η _sp ) was determined by inserting it into the following equation.
η _sp /c=[η]+0.45×[η]2c (where [η] is the intrinsic viscosity)
[Η] = 1.23 × 10 ⁻⁴ M ^0.83
c = 0.7

[Reference Example 1]
<Manufacture of polycarbonate copolymer>
72.32 parts of isosorbide (hereinafter abbreviated as ISS), 80.24 parts of 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (hereinafter abbreviated as BCF), 154.61 parts of diphenyl carbonate, and tetra as a catalyst Methyl ammonium hydroxide 1.8 × 10 ⁻² parts and sodium hydroxide 1.6 × 10 ⁻⁴ parts were heated to 180 ° C. in a nitrogen atmosphere and melted. Thereafter, the degree of vacuum was adjusted to 13.4 kPa over 30 minutes. Thereafter, 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 vacuum was set 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 mole of the catalyst amount of tetrabutylphosphonium salt of dodecylbenzene sulfonate is added to deactivate the catalyst, then discharged from the bottom of the reaction tank under nitrogen pressure, cut with a pelletizer while cooling in the water tank. To obtain pellets. The resulting pellet had a viscosity average molecular weight of 19,600. The composition ratio was measured by NMR. The composition ratio was BCF / ISS = 29.8 / 70.2, and the deviation from the charging ratio was as small as 0.2.

<Manufacture of optical film>
Next, a 15 mm biaxial extrusion kneader manufactured by Technobel Co., Ltd. was attached with a T die having a width of 150 mm and a lip width of 500 μm and a film take-up device, and the resulting polycarbonate copolymer was formed into a film to form a transparent extruded film. Obtained. A sample having a size of 50 mm × 10 mm was cut out from a portion having a thickness of 68 ± 0.8 μm near the center of the obtained film, and the photoelastic constant and Tg were measured using the sample. In addition, a sample of 100 mm length and 70 mm width cut out in the same manner was uniaxially stretched 2.0 times in the length direction at 196 ° C. (Tg + 10 ° C.), and a stretched film having a length of 200 mm × width of 56 mm and a thickness of 49 μm Got. The stretched film was measured for retardation and wavelength dispersion. Since the difference between the composition ratio and the preparation ratio was as small as 0.2, the wavelength dispersion was not affected. The results are shown in Table 1.

[Reference Example 2]
<Manufacture of polycarbonate copolymer>
Except for using ISS 68.19 parts, BCF 90.94 parts, and diphenyl carbonate 154.61 parts, the same operation as in Reference Example 1 was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The resulting pellet had a viscosity average molecular weight of 19,200. The composition ratio was measured by NMR. The composition ratio was BCF / ISS = 33.7 / 67.3, and the deviation from the charging ratio was as small as 0.3.

<Manufacture of optical film>
This copolymer was dissolved in methylene chloride to prepare a dope having a solid concentration of 19% by weight. A cast film (thickness 81 ± 0.8 μm) was prepared from this dope solution by a known method. A 50 mm × 10 mm size sample was cut out from the portion having a thickness of 80 ± 0.8 μm near the center of the obtained film, and the photoelastic coefficient and Tg were evaluated in the same manner as in Reference Example 1 using the sample. As in Reference Example 1, the film was uniaxially stretched 2.0 times at Tg + 10 ° C. to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 62 μm. Since the difference between the composition ratio and the preparation ratio was as small as 0.2, the wavelength dispersion was not affected. In the same manner as in Reference Example 1, phase difference measurement and wavelength dispersion were measured. The results are shown in Table 1.

[ Reference Example 3]
<Manufacture of polycarbonate copolymer resin>
ISS 72.32 parts, 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (hereinafter abbreviated as BPEF) 93.09 parts, diphenyl carbonate 154.61 parts were used, and completely the same as Reference Example 1 The same operation was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The resulting pellet had a viscosity average molecular weight of 19,600. The composition ratio was measured by NMR. The composition ratio was BPEF / ISS = 29.8 / 70.2, and the deviation from the preparation ratio was as small as 0.2.

<Manufacture of optical film>
Next, a film (thickness 83 ± 0.8 μm) was prepared in the same manner as in Reference Example 1. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. In the same manner as in Reference Example 1, the film was uniaxially stretched at Tg + 10 ° C. by 2.0 times to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 64 μm, and retardation measurement and wavelength dispersion were measured. Since the difference between the composition ratio and the preparation ratio was as small as 0.2, the wavelength dispersion was not affected. The results are shown in Table 1.

[Example 1 ]
<Manufacture of polycarbonate copolymer resin>
Except for using ISS 61.99 parts, 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (hereinafter abbreviated as BPEF) 124.12 parts and diphenyl carbonate 154.61 parts, completely the same as Reference Example 1 The same operation was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The viscosity average molecular weight of the obtained pellet was 19400. The composition ratio was measured by NMR. The composition ratio was BPEF / ISS = 39.8 / 60.2, and the deviation from the preparation ratio was as small as 0.2.

<Manufacture of optical film>
Next, a film (thickness 84 ± 0.8 μm) was prepared in the same manner as in Reference Example 1. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. In the same manner as in Reference Example 1, the film was uniaxially stretched at Tg + 10 ° C. by 2.0 times to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 64 μm, and retardation measurement and wavelength dispersion were measured. Since the difference between the composition ratio and the preparation ratio was as small as 0.2, the wavelength dispersion was not affected. The results are shown in Table 1.

[Example 2 ]
<Manufacture of polycarbonate copolymer resin>
Except for using ISS 51.66 parts, BPEF 155.15 parts, and diphenyl carbonate 154.61 parts, the same operation as in Reference Example 1 was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The viscosity average molecular weight of the obtained pellet was 19000. The composition ratio was measured by NMR. The composition ratio was BPEF / ISS = 49.8 / 50.2, and the deviation from the preparation ratio was as small as 0.2.

<Manufacture of optical film>
Next, a film (thickness 82 ± 0.8 μm) was prepared in the same manner as in Reference Example 1. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. In the same manner as in Reference Example 1, the film was uniaxially stretched at Tg + 10 ° C. by 2.0 times to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 62 μm, and retardation measurement and wavelength dispersion were measured. Since the difference between the composition ratio and the preparation ratio was as small as 0.2, the wavelength dispersion was not affected. The results are shown in Table 1.

[Example 3 ]
<Manufacture of polycarbonate copolymer resin>
Except for using ISS 41.33 parts, BPEF 186.18 parts, and diphenyl carbonate 154.61 parts, the same operation as in Reference Example 1 was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The resulting pellet had a viscosity average molecular weight of 19,200. The composition ratio was measured by NMR. The composition ratio was BPEF / ISS = 59.7 / 40.3, and the deviation from the preparation ratio was as small as 0.3.

<Manufacture of optical film>
Next, a film (thickness 83 ± 0.8 μm) was prepared in the same manner as in Reference Example 1. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. In the same manner as in Reference Example 1, the film was uniaxially stretched at Tg + 10 ° C. by 2.0 times to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 63 μm, and retardation measurement and wavelength dispersion were measured. Since the difference between the composition ratio and the charging ratio was as small as 0.3, the wavelength dispersion was not affected. The results are shown in Table 1.

[Reference Example 7]
<Manufacture of polycarbonate copolymer resin>
Except for using 51.66 parts of ISS, 133.74 parts of BCF, and 154.61 parts of diphenyl carbonate, the same operation as in Reference Example 1 was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The viscosity average molecular weight of the obtained pellet was 18900.

<Manufacture of optical film>
This copolymer was dissolved in methylene chloride to prepare a dope having a solid concentration of 19% by weight. A cast film (thickness 81 ± 0.8 μm) was prepared from this dope solution by a known method. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. As in Reference Example 1, the film was uniaxially stretched 2.0 times at Tg + 10 ° C. to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 62 μm. In the same manner as in Reference Example 1, phase difference measurement and wavelength dispersion were measured. The results are shown in Table 2.

[ Reference Example 8]
<Manufacture of polycarbonate copolymer resin>
Except for using 30.99 parts of ISS, 217.21 parts of BPEF, and 154.61 parts of diphenyl carbonate, the same operation as in Reference Example 1 was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The viscosity average molecular weight of the obtained pellet was 19000.

<Manufacture of optical film>
Next, a film (thickness 83 ± 0.8 μm) was prepared in the same manner as in Reference Example 1. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. In the same manner as in Reference Example 1, the film was uniaxially stretched at Tg + 10 ° C. by 2.0 times to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 63 μm, and retardation measurement and wavelength dispersion were measured. The results are shown in Table 2.

[ Reference Example 9]
<Manufacture of polycarbonate copolymer resin>
Except for using ISS 20.66 parts, BPEF 248.24 parts, and diphenyl carbonate 154.61 parts, the same operation as in Reference Example 1 was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The resulting pellet had a viscosity average molecular weight of 19,200.

<Manufacture of optical film>
Next, a film (thickness 81 ± 0.8 μm) was prepared in the same manner as in Reference Example 1. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. In the same manner as in Reference Example 1, the film was uniaxially stretched at Tg + 10 ° C. by 2.0 times to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 62 μm, and retardation measurement and wavelength dispersion were measured. The results are shown in Table 2.

[Reference Example 10]
<Manufacture of polycarbonate copolymer resin>
Except for using ISS 15.5 parts, BCF 227.36 parts and diphenyl carbonate 154.61 parts, the same operation as in Reference Example 1 was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The viscosity average molecular weight of the obtained pellet was 16,500.

<Manufacture of optical film>
This copolymer was dissolved in methylene chloride to prepare a dope having a solid concentration of 19% by weight. A cast film (thickness 80 ± 0.8 μm) was prepared from this dope solution by a known method. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. Similarly to Reference Example 1, the film was uniaxially stretched 2.0 times at Tg + 10 ° C. to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 63 μm. In the same manner as in Reference Example 1, phase difference measurement and wavelength dispersion were measured. The results are shown in Table 3.

[ Reference Example 11]
<Manufacture of polycarbonate copolymer resin>
Except for using 10.33 parts of ISS, 279.27 parts of BPEF, and 154.61 parts of diphenyl carbonate, the same operation as in Reference Example 1 was performed to obtain an aromatic-aliphatic copolymer polycarbonate. The resulting pellet had a viscosity average molecular weight of 19,200.

<Manufacture of optical film>
Next, a film (thickness 85 ± 0.8 μm) was prepared in the same manner as in Reference Example 1. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. Similarly to Reference Example 1, the film was uniaxially stretched at Tg + 10 ° C. by 2.0 times to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 65 μm, and retardation measurement and wavelength dispersion were measured. The results are shown in Table 3.

[Comparative Example 1]
<Manufacture of polycarbonate copolymer resin>
To a reactor equipped with a thermometer, a stirrer and a reflux condenser, 9809 parts of ion-exchanged water and 2271 parts of 48% sodium hydroxide aqueous solution were added, and 1775 parts of 2,2-bis (4-hydroxyphenyl) propane and sodium hydrosulfite were added. After dissolving 3.5 parts and adding 7925 parts of methylene chloride, 1000 parts of phosgene was blown in at a temperature of 16 to 20 ° C. with stirring for 60 minutes. After completion of the phosgene blowing, 52.6 parts of p-tert-butylphenol and 327 parts of 48% aqueous sodium hydroxide solution were added, and 1.57 parts of triethylamine was further added, followed by stirring at 20 to 27 ° C. for 40 minutes to complete the reaction. . The methylene chloride layer containing the product was washed with dilute hydrochloric acid and pure water, and then methylene chloride was evaporated to obtain a polycarbonate resin. The resulting powder had a viscosity average molecular weight of 15,500.

<Manufacture of optical film>
The obtained polycarbonate resin was pelletized by a 15φ biaxial extrusion kneader. Next, a film (thickness 58 ± 0.8 μm) was prepared in the same manner as in Reference Example 1. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. The film was uniaxially stretched 2.0 times at Tg + 10 ° C. in the same manner as in Reference Example 1 to obtain a stretched film having a length of 200 mm × width of 56 mm and a thickness of 41 μm, and retardation measurement and wavelength dispersion were measured. The results are shown in Tables 1 and 2. This film has a high photoelastic coefficient of 80 × 10 ⁻¹² Pa ⁻¹ and a large birefringence due to stress. Therefore, light leakage occurs when used as a retardation film, which is not preferable. In addition, since the wavelength dispersion is positive dispersion, λ / 4 is not achieved in a wide band, and color loss is a problem.

[Comparative Example 2]
<Manufacture of polycarbonate copolymer resin>
To a reactor equipped with a thermometer, a stirrer, and a reflux condenser, 9809 parts of ion-exchanged water and 2271 parts of a 48% aqueous sodium hydroxide solution were added, and 585 parts of 2,2-bis (4-hydroxyphenyl) propane, 9,9- Dissolve 1969 parts of bis (4-hydroxy-3-methylphenyl) fluorene and 4.5 parts of sodium hydrosulfite, add 6604 parts of methylene chloride, and then add 60 parts of 1000 parts of phosgene at 16 to 20 ° C. with stirring. It took a minute to blow. After completion of the phosgene blowing, 70 parts of p-tert-butylphenol and 327 parts of a 48% aqueous sodium hydroxide solution were added, 1.57 parts of triethylamine was further added, and the reaction was terminated by stirring at 20 to 27 ° C. for 40 minutes. The methylene chloride layer containing the product was washed with dilute hydrochloric acid and pure water, and then methylene chloride was evaporated to obtain a polycarbonate resin having a fluorene skeleton. The obtained powder had a viscosity average molecular weight of 38,200. The composition ratio was measured by NMR. The composition ratio was BPA / BCF = 32.8 / 67.2, and the deviation from the charging ratio was as small as 0.2.

<Manufacture of optical film>
Next, a film (thickness 141 ± 0.8 μm) was prepared in the same manner as in Reference Example 2. The photoelastic coefficient and Tg of the obtained film were evaluated in the same manner as in Reference Example 1. The film was uniaxially stretched 2.0 times at Tg + 10 ° C. in the same manner as in Reference Example 1 to obtain a stretched film having a length of 200 mm × width of 56 mm and a thickness of 100 μm, and retardation measurement and wavelength dispersion were measured. Since the difference between the composition ratio and the preparation ratio was as small as 0.2, the wavelength dispersion was not affected. The results are shown in Table 1. This film has a high photoelastic coefficient of 44 × 10 ⁻¹² Pa ⁻¹ and a large birefringence due to stress. Therefore, light leakage occurs when used as a retardation film, which is not preferable.

[Comparative Example 3]
<Manufacture of polycarbonate copolymer>
Except for using ISS 7.67 parts, spiroglycol 24.2 parts, BCF 6.81 parts and diphenyl carbonate 32.45 parts, the same operation as in Reference Example 1 was performed to obtain a polycarbonate copolymer. The resulting pellet had a viscosity average molecular weight of 16,300. The composition ratio was measured by NMR. The composition ratio was ISS / SPG / BCF = 34.6 / 52.6 / 12.8, and the deviation from the charging ratio was as large as 0.8.

<Manufacture of optical film>
Next, a film (thickness 78 (± 0.8) μm) was prepared in the same manner as in Reference Example 1. The photoelastic constant of the obtained film was evaluated in the same manner as in Reference Example 1. In the same manner as in Reference Example 1, the film was uniaxially stretched 2.0 times at Tg + 10 ° C. to obtain a stretched film having a length of 200 mm × width of 57 mm and a thickness of 48 μm, and retardation measurement and wavelength dispersion were measured. Since the difference between the composition ratio and the charging ratio is as large as 0.8, it is difficult to control chromatic dispersion. The results are shown in Table 1.

[Comparative Example 4]
<Manufacture of polycarbonate copolymer>
To a reactor equipped with a thermometer, a stirrer, and a reflux condenser, 9809 parts of ion-exchanged water and 2271 parts of 48% aqueous sodium hydroxide were added, and 461 parts of 2,2-bis (4-hydroxyphenyl) propane, 9,9- Dissolve 2175 parts of bis (4-hydroxy-3-methylphenyl) fluorene and 4.5 parts of sodium hydrosulfite, add 6604 parts of methylene chloride, then add 60 parts of 1000 parts of phosgene at 16 to 20 ° C. with stirring. It took a minute to blow. After completion of the phosgene blowing, 70 parts of p-tert-butylphenol and 327 parts of a 48% aqueous sodium hydroxide solution were added, 1.57 parts of triethylamine was further added, and the reaction was terminated by stirring at 20 to 27 ° C. for 40 minutes. The methylene chloride layer containing the product was washed with dilute hydrochloric acid and pure water, and then methylene chloride was evaporated to obtain a polycarbonate copolymer having a fluorene skeleton. The composition ratio was measured by NMR. The obtained powder had a viscosity average molecular weight of 38,200.

<Manufacture of optical film>
Next, a film (thickness 164 (± 0.8) μm) was prepared in the same manner as in Reference Example 2. The photoelastic constant of the obtained film was evaluated in the same manner as in Reference Example 1. The film was uniaxially stretched 2.0 times at Tg + 10 ° C. in the same manner as in Reference Example 1 to obtain a stretched film having a length of 200 mm × width of 56 mm and a thickness of 100 μm, and retardation measurement and wavelength dispersion were measured. The results are shown in Table 2. This film has a high photoelastic constant of 42 × 10 ⁻¹² Pa ⁻¹ and a large birefringence due to stress. Therefore, light leakage occurs when used as a retardation film, which is not preferable.

[Comparative Example 5]
<Manufacture of polycarbonate copolymer>
To a reactor equipped with a thermometer, a stirrer, and a reflux condenser, 9809 parts of ion-exchanged water and 2271 parts of 48% sodium hydroxide aqueous solution were added, and 337 parts of 2,2-bis (4-hydroxyphenyl) propane, 9,9- Dissolve 2280 parts of bis (4-hydroxy-3-methylphenyl) fluorene and 4.5 parts of sodium hydrosulfite, add 6604 parts of methylene chloride, and then add 60 parts of 1000 parts of phosgene at 16 to 20 ° C. with stirring. It took a minute to blow. After completion of the phosgene blowing, 70 parts of p-tert-butylphenol and 327 parts of a 48% aqueous sodium hydroxide solution were added, 1.57 parts of triethylamine was further added, and the reaction was terminated by stirring at 20 to 27 ° C. for 40 minutes. The methylene chloride layer containing the product was washed with dilute hydrochloric acid and pure water, and then methylene chloride was evaporated to obtain a polycarbonate copolymer having a fluorene skeleton. The composition ratio was measured by NMR.

<Manufacture of optical film>
Next, a film (thickness 164 (± 0.8) μm) was prepared in the same manner as in Reference Example 2. The photoelastic constant of the obtained film was evaluated in the same manner as in Reference Example 1. The film was uniaxially stretched 2.0 times at Tg + 10 ° C. in the same manner as in Reference Example 1 to obtain a stretched film having a length of 200 mm × width of 56 mm and a thickness of 100 μm, and retardation measurement and wavelength dispersion were measured. The results are shown in Table 3. This film has a high photoelastic constant of 38 × 10 ⁻¹² Pa ⁻¹ and a large birefringence due to stress. Therefore, light leakage occurs when used as a retardation film, which is not preferable.

The retardation film of the present invention is extremely useful as a retardation film for liquid crystal display devices and organic EL displays.

Claims (9)

Following formula

The unit represented by ( A4 ) and the following formula

A retardation film units (B 1) consists of polycarbonate copolymer comprising, it satisfies the following (i) represented in.
(I) Unit (A4) and the unit (B 1) the molar ratio of (A4 / B 1) is 40/60 or more to 60/40 or less, R satisfying the following formula (1) to (3) (450) <R (550) <R (650) (1)
0.6 <R (450) / R (550) < 0.92 (2)
1.01 <R (650) / R (550) < 1.40 (3)
(However, R (450), R (550), and R (650) represent retardation values in the film plane at wavelengths of 450 nm, 550 nm, and 650 nm, respectively). The retardation film according to claim 1, wherein the absolute value of the photoelastic constant is 30 × 10 ⁻¹² Pa ⁻¹ or less. The retardation film is obtained by a method of longitudinal uniaxial stretching, lateral uniaxial stretching or biaxial stretching. (A) The stretching temperature is (Tg-20 ° C) to (Tg-20 ° C) to the glass transition temperature (Tg) of the polycarbonate copolymer. The retardation film according to claim 1, which is a film stretched under the conditions of (b) and (b) a draw ratio of 1.05 to 5 times. The retardation film according to claim 1, which is a retardation film for an organic EL display. A liquid crystal display device comprising the retardation film according to claim 1 . An organic EL display comprising the retardation film according to claim 1 . A circularly polarizing film comprising the retardation film according to claim 1 and a polarizing layer. A display element using the circularly polarizing film of claim 7 as an antireflection film. The display element according to claim 8, wherein the antireflection film is an antireflection film for an organic EL display.