KR20150048822A - Phase difference film, circularly polarizing plate, and image forming device - Google Patents

Abstract

An aspect of the present invention is a phase difference film comprising a cellulose acylate resin, wherein the cellulose acylate resin has an orientation degree of 0.03 or more and 0.15 or less and an orientation degree of the additive is 0.15 or less And Ro (550) is not less than 115 nm and not more than 160 nm, and the angle formed by the in-plane slow axis in the retardation film and the longitudinal direction of the retardation film is not less than 15 degrees and not more than 85 degrees.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a phase difference film, a circular polarizer,

The present invention relates to a retardation film, a circularly polarizing plate and an image display apparatus.

From the viewpoints of high luminous efficiency, low voltage driving, light weight and low cost, the organic electroluminescence device (organic EL device) has been widely used as a light source for planar illumination devices, a light source for optical fibers, a backlight for liquid crystal displays, A light source of an organic EL display (OLED), etc., as a light source has been extensively studied.

When a voltage is applied between the electrodes, electrons are injected from the cathode, holes from the anode are injected into the light-emitting layer, and electrons and holes are injected into the light- Is emitted.

In addition, indium tin oxide (ITO) is mainly used for an anode of a transparent conductive material because the anode has high electric conductivity, relatively high work function and high hole injection efficiency. A metal electrode is usually used for the cathode. As the metal electrode, Mg, Mg / Ag, Mg / In, Al, Li / Al and the like are mainly used from the viewpoint of work function in consideration of electron injection efficiency. These metal electrodes have a high light reflectivity and function not only as an electrode (cathode) but also a function of reflecting light emitted from the light emitting layer and increasing the amount of emitted light (light emission luminance). That is, not only the light emitted in the direction of the anode but also the light emitted in the direction of the cathode is mirror-reflected at the surface of the metal electrode, which is the cathode, and is taken out as the outgoing light from the transparent ITO electrode (anode) .

However, in the organic EL element, since the cathode has a mirror-finished surface with strong light reflectivity, external light is liable to be reflected in a state of not emitting light. As a result, in a device using an organic EL element as a light source, for example, an organic EL display (OLED) or the like, there arises a problem that the reflection of the room illumination occurs and the blackness in the spot is difficult to express and the contrast is lowered there was.

On the other hand, an optical film having various functions is used for an apparatus using an organic EL element as a light source. As an optical film used in an apparatus using an organic EL element as a light source, in the state where the organic EL element is not emitting light as described above, external light is likely to be reflected. To prevent this reflection, , A retardation film capable of forming a circularly polarizing plate having antireflection properties, and the like. As the retardation film for exhibiting such antireflection property, for example, a? / 4 retardation film whose in-plane retardation is about 1/4 of the wavelength? Of transmitted light can be mentioned.

Examples of such a retardation film include retardation films and films described in Patent Documents 1 to 4.

Patent Document 1 discloses a liquid crystal display device which comprises a quarter wave plate having an in-plane retardation of 1/4 wavelength given to transmitted light and a half-wave plate having an in-plane retardation of 1/2 wavelength, Bonded phase difference plates are described.

In Patent Document 2, an optically anisotropic layer (A) having an in-plane retardation of substantially? At a wavelength of 550 nm and an optically anisotropic layer (B) having an in-plane retardation of substantially? / 2 at a wavelength of 550 nm are laminated , And a retardation plate in which one of the layers is a layer formed of liquid crystalline molecules.

Patent Document 3 discloses a cellulose ester film comprising a retardation control agent having a function of controlling the retardation so that the refractive index of the cellulose ester film in the direction perpendicular to the stretching direction becomes large when the cellulose ester film is uniaxially stretched .

Patent Document 4 discloses that a molecular absorption wavelength derived from a transition electric dipole moment in a direction substantially perpendicular to a molecular long axis direction is longer than a molecular absorption wavelength derived from a transition electric dipole moment in a direction substantially parallel to a molecular long axis direction, Discloses an optical film containing at least one low-molecular compound having a transitional electric dipole moment in a direction substantially orthogonal to the major axis of the molecule larger than a transitional electric dipole moment in a direction substantially parallel to the major axis of the molecule and an Rth enhancer .

According to Patent Documents 1 to 4, it is disclosed that a? / 4 phase difference can be realized.

As a retardation film having an in-plane retardation of? / 4, for example, when used as a circularly polarizing plate for imparting an antireflection function to an organic EL display or the like, unlike an optical pickup device for irradiating only light of a specific wavelength, It is required that the in-plane retardation is about 1/4 of the wavelength with respect to the light in the whole wavelength range. From this, it is required that the retardation imparted to the long wavelength light has a reverse wavelength dispersion property which satisfies the relationship that the retardation is larger than the retardation imparted to the short wavelength light, that is, the longer the wavelength is.

In addition, the phase difference film is required to have a thin film in order to satisfy not only the in-plane retardation of the light in the entire visible light wavelength but also the requirement of miniaturization of the device.

Japanese Patent Application Laid-Open No. 10-68816 Japanese Patent Laid-Open No. 2001-91741 Japanese Patent Application Laid-Open No. 2002-296421 Japanese Patent Application Laid-Open No. 2007-249180

An object of the present invention is to provide a retardation film which sufficiently suppresses deterioration of brittleness and is excellent in transparency and has an in-plane retardation of about 1/4 of the wavelength of light in a wide range of visible light wavelength. Another object of the present invention is to provide a circularly polarizing plate and an image display device provided with the retardation film.

One aspect of the present invention is a cellulose acylate resin and a long shape retardation film comprising an additive, wherein the additive is an additive represented by the following formula (A), and the cellulose acylate resin Is in the range of 0.03 or more and 0.15 or less and the degree of orientation of the additive calculated by the light absorption spectroscopy method is larger than 0.15 and the in-plane retardation value of the retardation film at a wavelength of 550 nm is 115 nm or more and 160 nm or less, And an angle formed by the in-plane slow axis of the phase difference film and the longitudinal direction of the retardation film is not less than 15 degrees and not more than 85 degrees.

In the formula (A), Q represents an aromatic hydrocarbon ring, a non-aromatic hydrocarbon ring, an aromatic heterocyclic ring, or a non-aromatic heterocyclic ring, and W a and W b represent a hydrogen atom bonded to an atom constituting the ring of Q An atom or a substituent, the atom to which Wa binds and the atom to which Wb is bonded are adjacent to each other in the ring of Q, the Wa and Wb are different from each other, and the Wa and Wb form a ring number and, R ¹ and R ² are, each independently represents a substituent, R ³ denotes a substituent, substitution degree m is 0 to 2, and when m is 2, can be two R ³ are the same or different from each other L ¹ and L ² each independently represents a single bond, an alkylene group, an alkenylene group, an alkynylene group, an -O- group, a - (C = O) = O) -O- group, -NR _L- group, -S- group, - (O = S = O) - group and - (C = O) -NR _L - group, Or a combination thereof, and R _L in L ¹ and L ² represents a hydrogen atom or a substituent.

Another aspect of the present invention is a circularly polarizing plate having the retardation film.

According to another aspect of the present invention, there is provided an image display apparatus including the retardation film.

The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and accompanying drawings.

Fig. 1 is a schematic view for explaining the contraction magnification in oblique stretching. Fig.
Fig. 2 is a schematic view showing an example of a rail pattern of a warp stretcher applicable to manufacture of a retardation film according to an embodiment of the present invention. Fig.
Fig. 3 is a schematic view showing a method for producing a retardation film according to an embodiment of the present invention (an example in which the film is loosened from a long film material roll and then obliquely stretched).
Fig. 4 is a schematic view showing a method for producing a retardation film according to an embodiment of the present invention (an example in which oblique stretching is continuously performed without winding a long film web). Fig.
5 is a schematic diagram showing an example of the configuration of the organic EL display device according to the embodiment of the present invention.

According to the studies of the present inventors, it has been found that the retardation plate or film described in Patent Documents 1 to 4 has a retardation of about 1/4 of the wavelength with respect to light in all the visible light wavelengths, It has been difficult to realize a retardation plate or a film sufficiently suppressed.

Specifically, the retardation films described in Patent Documents 1 and 2 laminate two or more different types of plates or layers, making thin film formation difficult. In addition, since it is necessary to stack two or more kinds of layers while strictly adjusting the angle and phase difference, the productivity is poor. From this point of view, there is a demand for a phase difference film that is more easily thinned and has a good reverse wavelength dispersion property. In order to realize this, it has been required to realize a? / 4 phase difference with one layer (single layer).

In the films described in Patent Documents 3 and 4, retardation control agents and the like are added to cellulose acylate to realize in-plane retardation of? / 4. However, since the in-plane retardation retardation is low, In order to obtain a desired retardation, it has been necessary to thicken the film, add another retardation enhancer, or increase the stretching magnification of the film. Addition of the other retardation enhancer may increase the total amount of the additive to be added to the resin so that the transparency may be impaired. In addition, if the stretching magnification of the film is increased, the brittleness of the film is lowered, and there is a fear that the film becomes fragile.

Further, in the above circular polarizer, the in-plane slow axes of the retardation film are bonded to the absorption axis of the polarizer in such a manner that they are inclined at a desired angle such as 45 degrees. Further, the polarizer is generally obtained by stretching in a long direction at a high magnification, so that the absorption axis formed by the stretching often coincides with the long direction. In this respect, when a retardation film in which an in-plane slow axis in a plane is obliquely stretched so as to be inclined at a desired angle of 45 DEG or the like is used as the retardation film, a long retardation film and a long polarizer are successively joined to form a circular polarizer It becomes possible to manufacture. From this, a retardation film obtained by oblique stretching attracts attention.

However, in oblique stretching, since the slow axis needs to be inclined, the stretching magnification becomes higher than that in uniaxial stretching, and therefore, in the cellulose ester film such as the cellulose acylate film described in Patent Document 3 and Patent Document 4 , The brittleness of the film is lowered, and the film tends to be fragile.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a cellulose acylate film having a sufficiently thin thickness, sufficiently suppressing deterioration in brittleness, having excellent transparency, And a phase difference film that is about 1/4 of the wavelength. Another object of the present invention is to provide a circularly polarizing plate and an image display device provided with the retardation film.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

<Retardation film>

A retardation film according to an embodiment of the present invention is a retardation film having a long shape including a cellulose acylate resin and an additive, wherein the additive is an additive represented by the above formula (A) An orientation degree of the cellulose acylate resin is 0.03 or more and 0.15 or less and an orientation degree of the additive calculated by a light absorption spectroscopy method is larger than 0.15 and an in-plane retardation value of the retardation film at a wavelength of 550 nm is 115 nm or more and 160 nm or less, The angle formed by the in-plane slow axis in the film and the longitudinal direction of the retardation film is 15 ° or more and 85 ° or less.

According to such a constitution, even in the case of a cellulose acylate film having a sufficiently thin thickness, the retardation of brittleness can be sufficiently suppressed and the in-plane retardation value can be reduced to 1/4 of the wavelength with respect to light in a wide range of visible light wavelength (? / 4 phase difference film) is obtained.

This is considered to be due to the following.

When a? / 4 retardation film having an in-plane retardation value of about 1/4 of a wavelength? Is prepared by obliquely stretching a cellulose acylate resin, the degree of orientation of the cellulose acylate resin is increased to realize? / 4 retardation , The film may be broken. Accordingly, by using the additive represented by the above formula (A) as the additive, the degree of orientation of the additive is increased and the degree of orientation of the cellulose acylate resin is relatively lowered as described above, so that the degree of orientation of the cellulose acylate resin is made too high And it is considered that the? / 4 phase difference can be realized. As a result, it is considered that a film capable of realizing a? / 4 phase difference is obtained which is sufficiently thin and has high transparency since the fracture is sufficiently suppressed. In addition, since the angle formed by the in-plane slow axis of the retardation film and the longitudinal direction of the retardation film is inclined as described above, it is possible to manufacture the circularly polarizing plate as long as it is.

Further, when this retardation film is applied to an image display apparatus such as an organic EL display, an image display apparatus capable of sufficiently suppressing reflection of external light and displaying a good image can be obtained.

In the present specification, the term &quot;? / 4 retardation film &quot; refers to a film having an in-plane retardation value of about 1/4 of a film with respect to a predetermined light wavelength (usually visible light region).

Further, since the? / 4 retardation film obtains substantially complete circularly polarized light in the wavelength range of visible light, it is preferable that the in-plane retardation value in the wavelength range of visible light is in the range of? / 4 retardation It is preferably a film. In the present specification, the term "phase difference in in-plane retardation value in the wavelength range of visible light" means that the in-plane retardation value is larger in the wavelength range of 400 to 700 nm than in the longer wavelength range .

In the retardation film, the orientation degree (Spol) of the cellulose acylate resin is preferably 0.03 or more and 0.15 or less, more preferably 0.05 or more and 0.15 or less, and still more preferably 0.07 or more and 0.14 or less. When the degree of orientation (Spol) of the cellulose acylate resin is within the above range, it is possible to sufficiently realize the? / 4 phase difference by increasing the degree of orientation (Sa) of the additive while sufficiently suppressing the decrease in brittleness.

The orientation degree (Spol) of the cellulose acylate resin can be adjusted by the following.

For example, first, the degree of orientation (Spol) of the cellulose acylate resin can be adjusted by the composition and the like of the cellulose acylate resin. More specifically, the lower the total acyl group substitution degree, the smaller the Spol tends to be. As the substituent, the bulky acyl group or the large acyl group tends to have a smaller Spol, and conversely, the shorter the acyl group or the smaller the steric group, the greater the Spol.

Next, when the plasticizer is contained in the retardation film, the degree of orientation (Spol) of the cellulose acylate resin can be adjusted by the kind of the plasticizer and the amount of the plasticizer added. The degree of orientation (Spol) of the cellulose acylate resin is, for example, in the case of using a plasticizer having a large volume which easily interacts with the cellulose acylate resin, although the degree of the plasticizer varies depending on the interaction force with the cellulose acylate resin and steric hindrance etc. , Compared with the case where no plasticizer is added. In addition, in the case of using a plasticizer having a small interaction with the cellulose acylate resin and a small amount of steric hindrance, the degree of decrease in the degree of orientation (Spol) of the cellulose acylate resin is also small. Further, as the amount of the plasticizer added increases, the degree of orientation (Spol) of the cellulose acylate resin tends to decrease.

Finally, the degree of orientation (Spol) of the cellulose acylate resin can be adjusted according to the stretching conditions at the time of producing the retardation film. For example, if the stretching temperature is increased, the Spol tends to be small. On the contrary, if the stretching temperature becomes unfavorable, the Spol tends to become large. Further, when the stretching magnification is increased, the Spol generally tends to become larger. On the other hand, if the stretching magnification is unfavorable, the Spol tends to be small.

Also, the degree of orientation (Sa) of the additive is greater than 0.15. The orientation degree Sa of the additive is desirably large, and in reality, 1 is the upper limit, so 1 is the upper limit value. The degree of orientation (Sa) of the additive is preferably 0.15 or more, more preferably 0.16 or more and 0.5 or less, and more preferably 0.16 or more and 0.4 or less. When the orientation degree Sa of the additive is within the above range, the? / 4 phase difference can be realized in the thin film.

The degree of orientation (Sa) of the additive can be adjusted by the following.

For example, the degree of orientation (Sa) of the additive can be adjusted first according to the chemical structure of the additive and the like. Specifically, in the structure represented by the formula (A), when the linearity of the partial structure represented by R ¹ -L ¹ - (QL ² ) _n -R ² is high and rigid, Sa tends to increase. More specifically, for example, the moiety Q is an aromatic hydrocarbon ring, a non-aromatic hydrocarbon ring, an aromatic heterocyclic ring, or a non-aromatic heterocyclic ring, and the moiety R ¹ and R ² is a cycloalkyl group (cyclohexyl, Cyclopentene-1-yl group and 2-cyclohexene-1-yl group), an aryl group (phenyl group, p-tolyl group and naphthyl group) (2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl and 2-pyridyl groups), aryloxy groups (such as a phenoxy group, a 2-methylphenoxy , A 4-tert-butylphenoxy group, a 3-nitrophenoxy group and a 2-tetradecanoylaminopheno group), arylthio groups (phenylthio group, p-chlorophenylthio group and m- (C = O) - group, - (C = O) - group, and - (C = O) - group, wherein L ¹ and L ² each independently represent a single bond, an alkylene group, an alkenylene group, an alkynylene group, O) -O- group, -NR _L - group, When Sa represents a divalent linking group selected from the group consisting of -S-, - (O = S = O) - and - (C = O) -NR _L - groups or combinations thereof, Sa tends to be large. Among them, L ¹ and L ² are preferably -O-, -C (O) -O-, -O- (C = O) -, - (C = O) - group or the like, Sa tends to be larger.

The degree of orientation (Spol) of the cellulose acylate resin and the degree of orientation (Sa) of the additive are values calculated by the absorption spectroscopic method. Specifically, the degree of orientation can be measured by the following method.

First, as the apparatus for measuring the degree of orientation, specifically, the following apparatus can be mentioned. For example, a spectrophotometer capable of using linearly polarized light as incident light in a wavelength range of 220 to 450 nm, and the like can be given. It is also possible to use a commercially available spectrophotometer corresponding to a wavelength range of 220 to 450 nm (for example, V-7100 manufactured by Nippon Bunko K.K.) or the like. At this time, a polarizer corresponding to the ultraviolet region (for example, Glan-Taylor prism; extinction ratio 1 × 10 ^-5 ) is provided on the light source side of the spectrophotometer. When the integrating sphere is provided on the detection side, the integrating sphere is removed, and a commercially available depolarization filter is provided instead.

Next, a method of calculating the degree of orientation (Sa) of the additive will be described.

A film sample (F1) of the object to be measured containing the additive is set in the apparatus, and the absorption spectrum is measured in the wavelength range of 220 to 450 nm. At this time, a sample is provided so that the arbitrary reference direction of the film (the direction of the slow axis of the film in the present invention) coincides with the transmission axis of the polarizer, and the spectrum is measured to determine the absorbance (Aa) I ask. In addition, a sample was placed so that the reference direction of the film was 90 degrees with respect to the transmission axis of the polarizer at the same position of the same sample F1, and the spectrum was measured in the same manner to obtain the absorbance Aa of the absorption V).

Using the obtained absorbances Aa (P) and Aa (V), the orientation degree Sa of the additive is calculated according to the following formula.

Sa = {Aa (V) - Aa (P)} / {Aa (V) + 2Aa (P)}

Here, when Sa = 0, it means that the orientation is random (that is, not oriented), and Sa = 1 means that it is fully oriented.

The method of calculating the degree of orientation (Spol) of the cellulose acylate resin is as follows.

A film obtained by adding 10% of azobenzene to the film sample (F1) of Sa is used instead of the cellulose acylate of the same kind as the film sample (F1) and the additive is not added. When the film sample F1 yielding Sa is a stretched film, the spol-calculating film sample F2 is also stretched under the same stretching temperature condition and stretching magnification conditions as the film sample F1 obtained by Sa . Here, the "stretching temperature condition identical to (F1)" means that the stretching temperature is selected so that the difference between the glass transition temperature of F1 and the actual stretching temperature and the difference between the glass transition temperature of F2 and the actual stretching temperature . The produced F2 was placed in a spectrophotometer in which a polarizer was disposed on the light source side in the same manner as in the calculation of Sa and the F2 was irradiated in the direction in which the transmission axis of the polarizer coincided with the reference direction of the film (Apol) (P) derived from azobenzene and the absorbance (Apol) (V) when tilted at 90 ° are obtained.

Using the obtained absorbances Apol (P) and Apol (V), the degree of orientation (Spol) of the cellulose acylate resin is calculated according to the following formula.

Spol = {Apol (V) -Apol (P)} / {Apol (V) + 2Apol (P)

Further, the glass transition temperature (Tg) of the film can be measured using a DSC-7 differential scanning calorimeter (manufactured by Perkin Elmer), a TAC7 / DX thermal analyzer controller (manufactured by Perkin Elmer), a differential scanning calorimeter Q2000 Manufactured by Nippon Shokubai Co., Ltd.) and differential scanning calorimeter DSC6220 (SII, manufactured by Nanotechnology Co., Ltd.), can be measured by a differential scanning calorimetry method.

1) 10.0 mg of the film piece was weighed to 0.01 mg, sealed in an aluminum pan, and set on a sample holder of DSC6220 (manufactured by SII, Nanotechnology Co.). As a reference, use an empty aluminum fan.

2) Perform the temperature control of the Heat-Cool-Heat under the conditions of a measurement temperature of 30 to 240 ° C, a temperature increase rate of 5 ° C / min, and a temperature decrease rate of 10 ° C / min. Then, the glass transition temperature is obtained based on the data in the 2nd Heat. Specifically, a tangent line indicating the maximum inclination is drawn between the extension line of the base line before the rise of the first endothermic peak and the peak point of the rise end of the first endothermic peak, and the intersection thereof is taken as the glass transition temperature Tg .

The retardation film has an in-plane retardation value (Ro) (550) at a wavelength of 550 nm of not less than 115 nm and not more than 160 nm. The in-plane retardation value (Ro) 550 is preferably 120 nm or more and 160 nm or less, more preferably 130 nm or more and 150 nm or less. The retardation film whose Ro (550) falls within the above range can preferably function as a? / 4 retardation film.

The retardation film preferably has a retardation value (Rth) (550) in the thickness direction at a wavelength of 550 nm of 50 nm or more and 250 nm or less.

The retardation film has an in-plane retardation value (Ro) 450 at a wavelength of 450 nm, an in-plane retardation value Ro at a wavelength of 550 nm (Ro) 550, an in-plane retardation value Ro at a wavelength of 650 nm, (650) preferably satisfy the following formulas (1) and (2).

0.72? Ro (450) / Ro (550)? 0.94 (One)

0.83? Ro (550) / Ro (650)? 0.98 (2)

If the Ro 450, Ro 550 and Ro 650 are within the above range, a phase difference of? / 4 can be given to light of a wider wavelength region. Therefore, it can function more favorably as a? / 4 retardation film. In addition, when this retardation film is applied to an image display apparatus such as an organic EL display, light leakage or the like when black display is performed can be reduced. Concretely, when the above formula (1) is satisfied, the reproducibility of blue is high. When the formula (2) is satisfied, the reproducibility of red is high.

In the retardation film, it is preferable that Ro (450) / Ro (550) is 0.72 or more and 0.94 or less, more preferably 0.79 or more and 0.91 or less, and still more preferably 0.81 or more and 0.89 or less as described above. As described above, it is preferable that Ro (550) / Ro (650) is 0.83 or more and 0.98 or less, more preferably 0.84 or more and 0.97 or less, still more preferably 0.85 or more and 0.95 or less.

Is the in-plane retardation value Ro at the wavelength? Under the condition of 23 占 폚 and 55% RH and Rth (?) Is the retardation value at the wavelength? (Rth) in the thickness direction of the film. For example, Ro (550) is the in-plane retardation value (Ro) at a wavelength of 550 nm under the condition of 23 占 폚 and 55% RH.

Further, Ro and Rth in the retardation film are respectively defined by the following equations.

(1): Ro = (nx-ny) xd (nm)

(2): Rth = {(nx + ny) / 2-nz} xd (nm)

(In the formulas (1) and (2), nx represents the refractive index in the slow axis direction (x) where the refractive index becomes maximum in the in-plane direction of the retardation film, and ny represents the in- Wherein n represents the refractive index in the thickness direction z of the retardation film and d (nm) represents the thickness of the retardation film. The refractive index of the retardation film in the direction (y) perpendicular to the slow axis direction (x)

Also, Ro and Rth can be measured using an automatic birefringence meter. Examples of the automatic birefringence index system include AxoScan manufactured by Axometrics, KOBRA-21ADH manufactured by Oji Keisoku Kikai K.K., and the like. Specifically, it can be measured by the following method.

1) Humidify the phase difference film at 23 ° C and 55% RH. The average refractive index of the retardation film after humidity control at 450 nm, 550 nm, and 650 nm is measured using an Abbe refractometer and a spectral light source. Further, the thickness of the optical film is measured using a film thickness meter.

2) The phase difference film Ro (450), Ro (550) or Ro (650) in the in-plane direction when light having a wavelength of 450 nm, 550 nm or 650 nm is incident parallel to the normal line of the film surface Is measured with AxoScan manufactured by Axometrics. The phase axis in the plane of the retardation film can also be confirmed by AxoScan manufactured by Axometrics.

3) The angle (incident angle) of phi with respect to the normal line of the surface of the retardation film was measured with AxoScan manufactured by Axometrics Co., with the slow axis in the plane of the retardation film as the tilt axis (rotation axis) (R) (?) When light having a wavelength of 450 nm, 550 nm, or 650 nm is incident on the photodetector. The measurement of the phase difference (R) (phi) can be performed at six points per 10 deg. In the range of 0 DEG to 50 DEG.

4) Calculate nx, ny and nz from Ro and R (φ) measured at each wavelength λ and the above-mentioned average refractive index and film thickness by AxoScan manufactured by Axometrics do. Based on the above equation, the retardation Rth (450), Rth (550), or Rth (650) in the thickness direction at a measurement wavelength of 450 nm, 550 nm, or 650 nm is calculated.

Further, Ro (450) / Ro (550) can be calculated from the obtained Ro (450) and Ro (550). Ro (550) / Ro (650) can be calculated from the obtained Ro (550) and Ro (650).

The retardation film preferably has an angle between the in-plane slow axis and the longitudinal direction thereof, that is, an in-plane orientation angle of 15 ° or more and 85 ° or less and 30 ° or more and 60 ° or less, And more preferably 40 deg. Or more and 50 deg. Or less. When the in-plane orientation angle is in the above-mentioned range, the retardation film is unwound from the roll and has a slow axis in the oblique direction with respect to the long direction, and a polarizer film wound in a roll shape and having a transmission axis parallel to the long direction, The circular polarizing plate can be easily manufactured by joining the polarizing plates together by roll-to-roll bonding so that they overlap each other. Thereby, the cut loss of the film is small, which is advantageous from the viewpoint of production.

Hereinafter, the components included in the retardation film according to the present embodiment will be described. As described above, the retardation film may contain other components as long as it comprises a cellulose acylate resin and an additive, and the additive is an additive represented by the above formula (A).

(Cellulose acylate resin)

The cellulose acylate resin used in the present embodiment is a compound obtained by esterifying a cellulose with a carboxylic acid. That is, the cellulose acylate resin is a compound obtained by dehydrating and condensing a hydroxyl group of cellulose and a carboxyl group of a carboxylic acid to form an acyl group. The carboxylic acid is not particularly limited, and examples thereof include an aliphatic carboxylic acid having about 2 to 22 carbon atoms and an aromatic carboxylic acid having about 2 to 22 carbon atoms. Among them, a lower fatty acid having 6 or less carbon atoms is preferable. The carboxylic acid may be used singly or in combination of two or more kinds.

The acyl group of the cellulose acylate resin is not particularly limited and may be linear or branched. The acyl group may have a cyclic structure or may have another substituent. When the total substitution degree of the acyl group of the cellulose acylate resin is constant, the more the carbon number of the acyl group is, the more likely the birefringence tends to be lowered. For this reason, the number of carbon atoms of the acyl group is preferably 2 to 6, more preferably 2 to 4, and even more preferably 2 to 3, from the viewpoint of transparency and the like.

Specific examples of the cellulose acylate resin include cellulose acetate such as triacetyl cellulose and mixed fatty acid esters such as cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate and cellulose acetate phthalate . Among them, cellulose acetate, cellulose acetate butyrate and cellulose acetate propionate are preferable. The butyryl group which may be contained in the cellulose acylate resin may be linear or branched.

The total substitution degree of the acyl group of the cellulose acylate resin may be about 1.5 to 3. The total degree of substitution of the acyl group is preferably from 1.5 to 2.5 from the viewpoint of enhancing the phase difference manifestation. Of these, the substitution degree of the acyl group having 3 or more carbon atoms is preferably 2 or less. When the substitution degree of the acyl group having 3 or more carbon atoms is within the above range, it is preferable from the viewpoint of phase difference manifestation.

The substitution degree of the acyl group of the cellulose acylate resin can be measured by the method described in ASTM-D817-96.

In the cellulose acylate resin, the total number of carbon atoms of the acyl group per glucose unit is preferably 6.5 or less, more preferably 4 to 6.3, and further preferably 4.4 to 6.2. The total carbon number (acyl group total carbon number) of the acyl group per glucose unit is the sum of the carbon numbers of the acyl group bonded to one glucose unit of the cellulose acylate resin. For example, the total number of carbon atoms of the acyl group can be obtained by using the following formula.

DS (k) in this formula represents the acyl group substitution degree of the carbon number (k) in the glucose unit per unit of the cellulose acylate resin. For example, when the acyl group is an acetyl group, the number of carbon atoms is 2, and the acetyl group substitution degree is expressed as DS (2).

When the total number of carbon atoms of the acyl group is within the above range, the haze value of the obtained retardation film is adjusted to maintain sufficient transparency.

The number average molecular weight (Mn) of the cellulose acylate resin is preferably in the range of 6 × 10 ⁴ to 3 × 10 ⁵ , more preferably in the range of 7 × 10 ⁴ to 2 × 10 5, ⁵ &lt; / RTI &gt;

The molecular weight of the cellulose acylate resin, such as weight average molecular weight (Mw) and number average molecular weight (Mn), is measured using gel permeation chromatography (GPC). The measurement conditions are as follows.

Solvent: methylene chloride;

Column: Three shodex K806, K805 and K803G (manufactured by Showa Denko K.K.) are connected and used;

Column temperature: 25 캜;

Sample concentration: 0.1 mass%;

Detector: RI Model 504 (manufactured by GL Science);

Pump: L6000 (manufactured by Hitachi Seisakusho Kabushiki Kaisha);

Flow rate: 1 ml / min

Calibration curve: Standard curve of polystyrene STK standard A calibration curve of 13 samples in the range of Mw = 1000000-500 of polystyrene (manufactured by TOSOH CORPORATION) is used. 13 samples are used at almost equal intervals.

The content of residual sulfuric acid in the cellulose acylate resin is preferably in the range of 0.1 to 45 mass ppm in terms of sulfur element, more preferably in the range of 1 to 30 mass ppm. It is considered that sulfuric acid remains in the film in a salt state. If the content of the residual sulfuric acid exceeds 45 mass ppm, the film tends to be broken at the time of heat stretching or cutting (slitting) after heat elongation. The content of the residual sulfuric acid can be measured by the method defined in ASTM D817-96.

The content of the free acid in the cellulose acylate resin is preferably 1 to 500 mass ppm, more preferably 1 to 100 mass ppm, and even more preferably 1 to 70 mass ppm. If the content of the free acid is within the above range, the film is hardly broken at the time of heat stretching or slitting after heat elongation as described above. The content of the free acid can be measured by the method specified in ASTM D817-96.

The cellulose acylate resin may contain a small amount of a metal component. It is believed that the trace amount of metal component is derived from the water used in the synthesis process of the cellulose acylate resin. As such a metal component, it is preferable that the content of the component that can become insoluble nuclei is as small as possible. Particularly, metal ions such as iron, calcium, magnesium and the like may form insolubles by forming salts with resin degradation products and the like, which may contain organic acidic groups. In addition, the calcium (Ca) component can easily form an acidic component such as a carboxylic acid or a sulfonic acid and also many ligands and a coordination compound (that is, a complex), and a scum derived from a large amount of insoluble calcium ) May be formed.

Specifically, the content of the iron (Fe) component in the cellulose acylate resin is preferably 1 mass ppm or less. The content of the calcium (Ca) component in the cellulose acylate resin is preferably 60 mass ppm or less, and more preferably 0 to 30 mass ppm. The content of the magnesium (Mg) component in the cellulose acylate resin is preferably 0 to 70 mass ppm, more preferably 0 to 20 mass ppm.

The content of the metal component such as the iron (Fe) component, the calcium (Ca) component and the magnesium (Mg) component can be adjusted by subjecting the well-cleaned cellulose acylate resin to pretreatment with a micro digest wet cracking apparatus (sulfuric acid decomposition) , And ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer).

The content of the residual alkaline earth metal, residual sulfuric acid and residual acid can be adjusted by thoroughly washing the cellulose acylate resin obtained by the synthesis.

The method for producing the cellulose acylate resin is not particularly limited as far as the cellulose acylate resin can be produced, and known production methods can be used. Specifically, for example, synthesis can be performed with reference to the method described in Japanese Patent Application Laid-Open No. 10-45804. The cellulose of the raw material of the cellulose acylate resin is not particularly limited, but may be cotton linter, wood pulp and kenaf. As the cellulose acylate resin, a cellulose acylate resin made of a single raw material may be used, or two or more kinds of cellulose acylate resins having different raw materials may be used in combination.

(additive)

The additive used in this embodiment is the additive represented by the above formula (A).

Q in the formula (A) represents an aromatic hydrocarbon ring, a non-aromatic hydrocarbon ring, an aromatic heterocycle, or a non-aromatic heterocycle.

The aromatic hydrocarbon ring may be a monocyclic or condensed ring, preferably a monocyclic ring. Preferable examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzopyrylene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, And more preferably a benzene ring.

The non-aromatic hydrocarbon ring (aliphatic hydrocarbon ring) may be a monocyclic or condensed ring, preferably a monocyclic ring. Preferred examples of the non-aromatic hydrocarbon ring include cyclopropane ring, cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclobutene ring, cyclopentene ring, cyclohexane ring, cycloheptene ring or cyclooctane ring , Adamantane ring, bicyclononane ring, norbornane ring, norbornene ring, dicyclopentadiene ring, hydrogenated naphthalene ring and hydrogenated biphenyl ring. Preferable examples thereof include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring and a norbornene ring, and more preferably a cyclohexane ring and a cyclopentane ring.

The aromatic heterocycle may be a monocyclic or condensed ring, preferably a monocyclic ring. Preferable examples of the aromatic heterocycle include furan ring, benzofuran ring, thiophen ring, benzothiophen ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, azacarbazole ring The carbazole ring may be substituted with at least one of the carbon atoms constituting the carbazole ring group by a nitrogen atom), triazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, Benzothiazole ring, benzimidazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazin ring, pyrimidine ring, triazine ring, quinoline ring, thiopyran ring, thiopyran ring, The present invention relates to the use of a compound represented by the general formula (I) or a pharmaceutically acceptable salt thereof, wherein the compound is selected from the group consisting of a benzene ring, an isoquinoline ring, a cyinoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, Ring, dibenzocarbazole ring, benzodifuran ring, benzodithiophene , Phenanthroline ring, phenanthroline ring, acridine ring, benzoquinoline ring, phenanthrene ring, phenanthridine ring, phenanthroline ring, cyclin ring, quinton ring ring, tepenic ring ring, quininod ring ring, A naphthothiophene ring, a naphthothiophene ring, a naphthothiophene ring, an anthrafuran ring, an anthradifuran ring, an anthracene ring, an anthracene ring, an anthracene ring, an anthracene ring, And anthiophene ring. Of these, pyridine ring, benzothiazole ring and benzoxazole ring are preferable.

The non-aromatic heterocyclic ring may be a monocyclic or condensed ring, preferably a monocyclic ring. Preferable examples of the non-aromatic heterocycle include a tetrahydrofuran ring, a tetrahydropyran ring, a dioxolane ring, a dioxane ring, a pyrrolidine ring, a pyridone ring, a pyridazinone ring, an imide ring, a piperidine ring, A heterocyclic ring, a dihydrothiazole ring, a piperidine ring, an aziridine ring, an azetidine ring, an azepine ring, an azepan ring, an imidazolidine ring, a pyrrolidine ring, Diazepine ring, tetrahydrothiophene ring and the like. Among them, pyridone ring, imidazole ring and pyrrolidine ring are preferable.

Wa and Wb in the formula (A) are each a hydrogen atom or a substituent group bonded to an atom (ring constituent atom) constituting the ring of Q, respectively. The atoms to which Wa is bonded and the atoms to which Wb is bonded are adjacent to each other in the Q ring. Wa and Wb are different from each other.

Wa and Wb may be bonded to each other to form a ring. At least one of Wa and Wb may have a ring structure.

When at least one of Wa and Wb is a ring structure, the ring structure is preferably an aromatic hydrocarbon ring, a non-aromatic hydrocarbon ring, an aromatic heterocycle, or a non-aromatic heterocycle.

Examples of the substituent represented by Wa and Wb include the following substituents. Specific examples include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom; An alkyl group such as methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group and 2-ethylhexyl group; A cycloalkyl group such as a cyclohexyl group, a cyclopentyl group and a 4-n-dodecenylhexyl group; Alkenyl groups such as vinyl group and allyl group; A cycloalkenyl group such as a 2-cyclopenten-1-yl group and a 2-cyclohexen-1-yl group; An alkynyl group such as an ethynyl group and a propargyl group; Aryl groups such as phenyl group, p-tolyl group and naphthyl group; A 2-thienyl group, a 2-furyl group, a 2-thienyl group, a pyrrolyl group, an imidazolyl group, an oxazolyl group, a thiazolyl group, a benzoimidazolyl group, a benzoxazolyl group, A heteroaryl group such as a zolinone group, a pyridyl group, a pyridinyl group and a 2-pyrimidinyl group; Cyano; A hydroxyl group; A nitro group; A carboxyl group; An alkoxy group such as methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group and 2-methoxyethoxy group; An aryloxy group such as a phenoxy group, a 2-methylphenoxy group, a 4-tert-butylphenoxy group, a 3-nitrophenoxy group and a 2-tetradecanoylaminophenoxy group; An acyl group such as an acetyl group and a pivaloylbenzoyl group; An acyloxy group such as a formyloxy group, an acetyloxy group, a pivaloyloxy group, a stearoyloxy group, a benzoyloxy group and a p-methoxyphenylcarbonyloxy group; Amino groups such as an amino group, a methylamino group, a dimethylamino group, an anilino group, an N-methyl-anilino group and a diphenylamino group; An acylamino group such as formylamino group, acetylamino group, pivaloylamino group, lauroylamino group and benzoylamino group; An alkylsulfonylamino group such as a methylsulfonylamino group, a butylsulfonylamino group, a phenylsulfonylamino group, a 2,3,5-trichlorophenylsulfonylamino group and a p-methylphenylsulfonylamino group, and an arylsulfonylamino group; A mercapto group; Alkylthio groups such as methylthio group, ethylthio group and n-hexadecylthio group; Arylthio groups such as phenylthio group, p-chlorophenylthio group and m-methoxyphenylthio group; N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N- Sulfamoyl group such as carbamoyl) sulfamoyl group; Sulfo group; Carbamoyl groups such as a carbamoyl group, an N-methylcarbamoyl group, an N, N-dimethylcarbamoyl group, an N, N-di-n-octylcarbamoyl group and an N- (methylsulfonyl) .

R ¹ and R ² in the formula (A) each independently represent a substituent. R ¹ and R ² may be the same or different. R ¹ and R ² include, for example, substituents shown below. Specific examples include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom; An alkyl group such as methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group and 2-ethylhexyl group; A cycloalkyl group such as a cyclohexyl group, a cyclopentyl group and a 4-n-dodecenylhexyl group; Alkenyl groups such as vinyl group and allyl group; A cycloalkenyl group such as a 2-cyclopenten-1-yl group and a 2-cyclohexen-1-yl group; An alkynyl group such as an ethynyl group and a propargyl group; Aryl groups such as phenyl group, p-tolyl group and naphthyl group; A heteroaryl group such as a 2-furyl group, a 2-thienyl group, a 2-pyrimidinyl group, a 2-benzothiazolyl group and a 2-pyridyl group; Cyano; A hydroxyl group; A nitro group; A carboxyl group; An alkoxy group such as methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group and 2-methoxyethoxy group; An aryloxy group such as a phenoxy group, a 2-methylphenoxy group, a 4-tert-butylphenoxy group, a 3-nitrophenoxy group and a 2-tetradecanoylaminophenoxy group; An acyloxy group such as a formyloxy group, an acetyloxy group, a pivaloyloxy group, a stearoyloxy group, a benzoyloxy group and a p-methoxyphenylcarbonyloxy group; Amino groups such as an amino group, a methylamino group, a dimethylamino group, an anilino group, an N-methyl-anilino group and a diphenylamino group; An acylamino group such as formylamino group, acetylamino group, pivaloylamino group, lauroylamino group and benzoylamino group; Alkylsulfonylamino group and arylsulfonylamino group such as methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group and p-methylphenylsulfonylamino group; A mercapto group; Alkylthio groups such as methylthio group, ethylthio group and n-hexadecylthio group; Arylthio groups such as phenylthio group, p-chlorophenylthio group and m-methoxyphenylthio group; N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N- Sulfamoyl group such as carbamoyl) sulfamoyl group; Sulfo group; An acyl group such as an acetyl group and a pivaloylbenzoyl group; Carbamoyl groups such as a carbamoyl group, an N-methylcarbamoyl group, an N, N-dimethylcarbamoyl group, an N, N-di-n-octylcarbamoyl group and an N- (methylsulfonyl) .

Among them, R ¹ and R ² are preferably an alkyl group (preferably an alkyl group having 1 to 20 carbon atoms), a cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms), an aryl group (preferably an aryl group having 6 to 20 carbon atoms And a heteroaryl group (preferably an aryl group having 4 to 20 carbon atoms), and more preferably an aryl group or a cycloalkyl group. The aryl group is preferably a substituted or unsubstituted phenyl group, more preferably a phenyl group having a substituent, more preferably a phenyl group having a substituent at the fourth position. The cycloalkyl group is preferably a substituted or unsubstituted cyclohexyl group, more preferably a cyclohexyl group having a substituent, and still more preferably a cyclohexyl group having a substituent at the 4-position. The substituent represented by R ¹ or R ² may also be substituted with the above substituent.

R ³ in the formula (A) represents a substituent. As R ³ , for example, the following substituents may be mentioned. Specifically, a hydrogen atom; A halogen atom such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom; An alkyl group such as methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group and 2-ethylhexyl group; Alkenyl groups such as vinyl group and allyl group; An alkynyl group such as an ethynyl group and a propargyl group; Cyano; A hydroxyl group; A nitro group; A carboxyl group; An alkoxy group such as methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group and 2-methoxyethoxy group; An acyloxy group such as a formyloxy group, an acetyloxy group, a pivaloyloxy group and a stearoyloxy group; An alkoxycarbonyl group such as a methoxycarbonyl group and an ethoxycarbonyl group; An aryloxycarbonyl group such as a phenoxycarbonyl group; An amino group such as an amino group, a methylamino group and a dimethylamino group; An acylamino group such as formylamino group, acetylamino group, pivaloylamino group and lauroylamino group; Alkylsulfonylamino groups such as methylsulfonylamino group and butylsulfonylamino group; A mercapto group; Alkylthio groups such as methylthio group, ethylthio group and n-hexadecylthio group; Sulfamoyl groups such as N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group and N-acetylsulfamoyl group; Sulfo group; An acyl group such as an acetyl group; Carbamoyl groups such as a carbamoyl group, an N-methylcarbamoyl group, an N, N-dimethylcarbamoyl group, an N, N-di-n-octylcarbamoyl group and an N- (methylsulfonyl) .

Among them, R ³ is preferably a hydrogen atom, a halogen atom, an alkyl group (preferably having 1 to 20 carbon atoms), an alkenyl group (preferably having 3 to 20 carbon atoms), an aryl group (preferably having 6 to 20 carbon atoms) (Preferably having from 4 to 20 carbon atoms), a hydroxyl group, a carboxyl group, an alkoxy group (preferably having from 1 to 20 carbon atoms), an aryloxy group (preferably having from 6 to 20 carbon atoms), an acyl group, An oxygen atom, an oxygen atom and an amino group are preferable, and R ³ is more preferably a hydrogen atom, a halogen atom, an alkyl group, a cyano group or an alkoxy group. These substituents may also be substituted with the substituents described above.

M in the formula (A) represents a degree of substitution, and here, represents the substitution degree of R ³ . m is an integer of 0 to 2; When m is 2, the two R ³ may be the same or different.

N in the formula (A) represents the polymerization degree. n is an integer of 1 to 10, preferably 1. When n is 2 or more, a plurality of Q, L ² , Wa, Wb, R ³ , m may be mutually the same or different.

L ¹ and L ² in the formula (A) each independently represent a single bond, an alkylene group, an alkenylene group, an alkynylene group, an -O- group, a - (C═O) A divalent linking group selected from the group consisting of -O-, -NR _L- , -S-, - (O = S = O) - and - (C = O) -NR _L - . (C = O) - group, - (C = O) -NH- group and -NH- (C = O) - Group is preferable. The term "L ^1" means that R ¹ and Q are directly connected to each other, and L ² means that R ² and Q are directly connected to each other.

Further, R _L in L ¹ and L ² represents a substituent. As R _L , for example, the following substituents may be mentioned. Specifically, a hydrogen atom; An alkyl group such as methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group and 2-ethylhexyl group; A cycloalkyl group such as a cyclohexyl group, a cyclopentyl group and a 4-n-dodecenylhexyl group; Aryl groups such as phenyl group, p-tolyl group and naphthyl group; A heteroaryl group such as a 2-furyl group, a 2-thienyl group, a 2-pyrimidinyl group, a 2-benzothiazolyl group and a 2-pyridyl group; And cyano group.

The compound represented by the formula (A) is preferably a compound represented by the formula (B).

(B)

Of Wa, Wb formula ^{(B), R 3, m} , L 1, L 2, R 1 and R ² are, Wa, Wb, in the general formula ^{(A) R 3, m,} L 1, L 2, R 1 And R ² , respectively.

In this embodiment, in order to keep the degree of orientation Sa of the additive represented by the formula (A) within the above range, the linearity of the partial structure represented by R ¹ -L ¹ - (QL ² ) _n -R ² is high It is preferable that the orientation is rigid. Therefore, the compound represented by the formula (B) is preferably a compound represented by the formula (1B).

(1B)

Wa, Wb of the general formula ^{(1B), R 3, m} , L 1, L 2, R 1 and R ² are, Wa, Wb, in the general formula ^{(A) R 3, m,} L 1, L 2, R 1 And R ² , respectively.

Hereinafter, the additives represented by the formula (A) are specifically exemplified, but the additives that can be used in the present embodiment are not limited at all by the following specific examples (the compounds Nos. 1 to 64). In the formulas in the following Tables, L ¹ , L ² , R ¹ and R ² may be represented by L ₁ , L ₂ , R ₁ and R ₂ .

As the specific examples of the additive represented by the formula (A), when the geometric isomer (trans-isomer and cis-isomer) is present, the above-mentioned compound is not particularly limited and may be any isomer unless otherwise specified. In addition, from the viewpoint of high phase difference manifestation, the trans is more preferable than the cis body.

Further, the additive represented by the formula (A) can be synthesized by a known method. Specifically, if it is exemplified, it can be synthesized with reference to the method described in Japanese Patent Application Laid-Open No. 2008-107767.

[Synthesis Example of Compound No. 5]

The compound No. 5 can be synthesized according to the following formula.

More specifically, synthesis is performed as follows.

Dihydroxybenzoic acid (3 g) was dissolved in toluene (30 mL), and thionyl chloride (4.2 mL) was added dropwise, followed by stirring for 2 hours. Toluene and thionyl chloride were distilled off under reduced pressure, 20 mL of toluene was added, and a solution of 2.4 g of o-aminothiophenol in toluene (5 mL) was added dropwise. The mixture was stirred at room temperature for 12 hours, and water and ethyl acetate were added to perform extraction. From the obtained organic layer, the solvent was distilled off under reduced pressure to obtain 3.5 g of the compound (i). The yield is 75%.

To 7.0 g of the compound (m), 45 ml of tetrahydrofuran was added, followed by cooling in an ice water bath. To this was added dropwise a solution of 3.5 g of the compound (i) in tetrahydrofuran (5 mL) and dimethylaminopyridine (2 mg) in tetrahydrofuran (1 mL) successively, and the mixture was stirred at room temperature for 3 hours. Water and ethyl acetate Extraction is performed. The solvent was distilled off from the organic layer under reduced pressure, and the obtained crude crystals were purified by silica gel chromatography (ethyl acetate / heptane) to obtain the compound No. 5.

The content of the additive represented by the formula (A) is appropriately set so as to give the required wavelength dispersion adjustment ability and phase difference manifestation. Specifically, it is preferably 1 to 10% by mass, more preferably 2 to 8% by mass with respect to the cellulose acylate resin. If the content of the additive represented by the general formula (A) is too small, desired retardation manifestation and wavelength dispersion adjustment tendency tends to be difficult to obtain. If the content of the additive represented by the formula (A) is too large, bleeding-out tends to occur easily. When the content of the additive represented by the formula (A) is within the above range, the retardation film can impart sufficient wavelength dispersion and high retardation.

The retardation film according to the present embodiment may further contain various plasticizers as required. Further, the plasticizer can contribute to the degree of orientation (Spol) of the cellulose acylate resin as described above. The plasticizer may be contained in order to improve the fluidity of the composition at the time of film production and the flexibility of the film. For example, the following compounds may be mentioned. First, a sugar ester compound will be described as a plasticizer.

(Ester ester compound)

The sugar ester compound is a compound having 1 to 12 furanose structures or pyranose structures and all or a part of the hydroxyl groups in the compound are esterified.

Preferable examples of such sugar ester compounds include sucrose ester compounds represented by the following formula (3).

(3)

R ₁ to R ₈ in the formula (3) represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group. R ₁ to R ₈ may be the same or different from each other.

The substituted or unsubstituted alkylcarbonyl group is preferably a substituted or unsubstituted alkylcarbonyl group having 2 or more carbon atoms. Examples of the substituted or unsubstituted alkylcarbonyl group include a methylcarbonyl group (acetyl group). Examples of the substituent of the alkyl group include an aryl group such as a phenyl group.

The substituted or unsubstituted arylcarbonyl group is preferably a substituted or unsubstituted arylcarbonyl group having 7 or more carbon atoms. Examples of the arylcarbonyl group include a phenylcarbonyl group. Examples of the substituent of the aryl group include an alkyl group such as a methyl group, and an alkoxyl group such as a methoxy group.

The average ester substitution degree of the sucrose ester compound is preferably 3.0 to 7.5. When the average ester substitution degree is less than 3.0 or more than 7.5, it is difficult to obtain sufficient compatibility with the cellulose ester.

Specific examples of the sucrose ester compound represented by the formula (3) include the following. R in the table represents R ₁ to R ₈ in the formula (3).

In addition, examples of the sugar ester compound include the compounds described in JP-A-62-42996 and JP-A-10-237084.

The content of the sugar ester compound is preferably 0.5 to 35 mass%, more preferably 5 to 30 mass%, based on the cellulose acylate resin.

Next, a plasticizer other than the sugar ester compound will be described. Examples of such plasticizers include polyester plasticizers, polyhydric alcohol ester plasticizers, polycarboxylic ester plasticizers (including phthalate ester plasticizers), glycolate plasticizers, ester plasticizers (citrate ester plasticizers, fatty acid esters Based plasticizer, phosphoric acid ester plasticizer, and trimellitic acid ester plasticizer), and the like. These may be used alone or in combination of two or more.

The polyester plasticizer is a compound obtained by reacting a mono- to tetravalent carboxylic acid with a mono- to hexavalent alcohol, preferably a compound obtained by reacting a divalent carboxylic acid with a glycol.

Examples of divalent carboxylic acids include glutaric acid, itaconic acid, adipic acid, phthalic acid, azelaic acid, sebacic acid and the like. Particularly, a compound using adipic acid, phthalic acid or the like as a dicarboxylic acid can impart good plasticity.

Examples of glycols include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, neopentylene glycol, diethylene glycol, triethylene glycol, Glycol and the like. Each of the divalent carboxylic acid and glycol may be used singly or two or more kinds thereof may be used in combination.

The polyester-based plasticizer may be any of esters, oligoesters, and polyesters. The molecular weight of the polyester plasticizer is preferably in the range of 100 to 10000 and more preferably in the range of 600 to 3000 in view of the effect of imparting plasticity.

The viscosity of the polyester-based plasticizer varies depending on the molecular structure and the molecular weight. However, in the case of the adipic acid-based plasticizer, compatibility with the thermoplastic resin is high and the effect of imparting plasticity is high. 25 &lt; 0 &gt; C). The polyester plasticizer may be used singly or in combination of two or more.

The polyhydric alcohol ester plasticizer is an ester compound (alcohol ester) of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and is preferably an aliphatic polyhydric alcohol ester of 2 to 20 equivalents. The polyhydric alcohol ester compound preferably has an aromatic ring or a cycloalkyl ring in the molecule.

Examples of aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, trimethylol propane, pentaerythritol and the like.

The monocarboxylic acid may be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, or an aromatic monocarboxylic acid. The monocarboxylic acid may be one kind or a mixture of two or more kinds. In addition, all of the OH groups included in the aliphatic polyhydric alcohol may be esterified, and some OH groups may be left as they are.

The aliphatic monocarboxylic acid is preferably a linear or branched chain fatty acid having 1 to 32 carbon atoms. The carbon number of the aliphatic monocarboxylic acid is more preferably 1 to 20, and still more preferably 1 to 10. Examples of such aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid and the like, and in order to enhance compatibility with the cellulose ester, acetic acid may be preferably used.

Examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid and the like.

Examples of aromatic monocarboxylic acids include benzoic acid; Those in which 1 to 3 alkyl or alkoxy groups (for example, methoxy or ethoxy) are introduced into the benzene ring of benzoic acid (e.g., toluic acid and the like); Aromatic monocarboxylic acids having two or more benzene rings (for example, biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralinecarboxylic acid, etc.), and preferably benzoic acid.

The molecular weight of the polyhydric alcohol ester plasticizer is not particularly limited, but is preferably 300 to 1,500, and more preferably 350 to 750. In order to make it difficult to volatilize, a larger molecular weight is preferable; In order to improve water permeability and compatibility with the cellulose ester, it is preferable that the molecular weight is small.

Specific examples of polyhydric alcohol ester plasticizers include trimethylolpropane triacetate, pentaerythritol tetraacetate, ester compounds (A) represented by the formula (I) described in Japanese Patent Laid-Open Publication No. 2008-88292, and the like.

The polybasic carboxylic acid ester plasticizer is an ester compound of a polyvalent carboxylic acid having 2 or more valences, preferably 2 to 20 valences, with an alcohol compound. The polycarboxylic acid is preferably an aliphatic polycarboxylic acid having 2 to 20 carbon atoms, an aromatic polycarboxylic acid having 3 to 20 carbon atoms, or an alicyclic polycarboxylic acid having 3 to 20 carbon atoms.

Examples of the polyvalent carboxylic acid include trivalent or higher aromatic polycarboxylic acids such as trimellitic acid, trimesic acid and pyromellitic acid or derivatives thereof; Aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid and tetrahydrophthalic acid; Oxydarboxylic acids such as tartaric acid, tartronic acid, malic acid and citric acid, and oxydicarboxylic acids are preferable for inhibiting volatilization from the film.

Examples of the alcohol compound include an aliphatic saturated alcohol compound having a straight chain or a side chain, an aliphatic unsaturated alcohol compound having a straight chain or side chain, an alicyclic alcohol compound, or an aromatic alcohol compound. The number of carbon atoms of the aliphatic saturated alcohol compound or aliphatic unsaturated alcohol compound is preferably 1 to 32, more preferably 1 to 20, and still more preferably 1 to 10. Examples of the alicyclic alcohol compound include cyclopentanol, cyclohexanol, and the like. Examples of the aromatic alcohol compound include phenol, para-cresol, dimethyl phenol, benzyl alcohol, cinnamyl alcohol and the like. The alcohol compound may be one kind or a mixture of two or more kinds.

The molecular weight of the polycarboxylic acid ester plasticizer is not particularly limited, but it is preferably from 300 to 1000, more preferably from 350 to 750. The molecular weight of the polycarboxylic acid ester plasticizer is preferably as large as possible from the viewpoint of suppressing bleedout; From the viewpoint of the moisture permeability and compatibility with the cellulose ester, a small amount is preferable.

The acid value of the polycarboxylic acid ester plasticizer is preferably 1 mgKOH / g or less, more preferably 0.2 mgKOH / g or less. Refers to the number of milligrams of potassium hydroxide required to neutralize the acid, the acid contained in 1 g of the sample (the carboxyl group present in the sample). The acid value is measured in accordance with JIS K0070.

Examples of the polycarboxylic acid ester plasticizers include ester compounds (B) represented by the formula (II) described in JP-A No. 2008-88292.

The polycarboxylic acid ester plasticizer may be a phthalic acid ester plasticizer. Examples of phthalate ester plasticizers include diethyl phthalate, dimethoxy ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate And the like.

Examples of glycolate-based plasticizers include alkyl phthalyl alkyl glycolates. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate and the like.

Ester plasticizers include fatty ester plasticizers, citric ester plasticizers, phosphate ester plasticizers, and trimellitic acid plasticizers.

Examples of the fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and the like. Examples of the citrate ester plasticizer include acetyltrimethyl citrate, acetyltriethyl citrate and acetyl tributyl citrate. Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyldiphenyl phosphate, octyldiphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate and tributyl phosphate. Examples of the trimellitic acid-based plasticizers include octyl trimellitate, n-octyl trimellitate, isodecyl trimellitate, isononyl trimellitate and the like.

The content of such a plasticizer is preferably 0.5 to 30 mass% with respect to the thermoplastic resin (cellulose acylate resin). If the content of the plasticizer exceeds 30 mass%, the film tends to cause bleed-out.

Further, the retardation film according to the present embodiment may further contain an antioxidant, an antistatic agent, a flame retardant, and the like for thermal decomposition at the time of molding and coloring by heat.

Examples of phosphorus-based flame retardants include triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, arylphosphonic acid compound, arylphosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphate ester, halogen-containing condensed phosphate ester, halogen-containing Condensed phosphonic acid esters, halogen-containing phosphorous acid esters, and the like. Specific examples thereof include triphenylphosphine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl) Phosphate, tris (tribromoneopentyl) phosphate, and the like.

The retardation film according to the present embodiment may further contain an ultraviolet absorber. The ultraviolet absorber may be a benzotriazole-based, 2-hydroxybenzophenone-based, salicylic acid phenyl ester-based, or the like. Specific examples thereof include 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis , And 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole; Benzophenones such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone.

Among them, an ultraviolet absorber having a molecular weight of 400 or more is difficult to volatilize at a high boiling point and is hardly scattered even at high temperature molding, so that a relatively small amount of the ultraviolet absorber can impart weather resistance to the resulting film.

Examples of ultraviolet absorbers having a molecular weight of not less than 400 include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] 1,1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol];

Hindered amines such as bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and bis (1,2,2,6,6-pentamethyl-4-piperidyl) system;

2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid bis (1,2,2,6,6-pentamethyl- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- Phenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, and the like; a hybrid system having both a structure of a hindered phenol and a hindered amine in a molecule;

(2) - [2-hydroxy-3,5-bis (?,? - dimethylbenzyl) phenyl] -2-benzotriazole or (2,2-methylenebis [4- (1,1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol]. These may be used singly or in combination of two or more.

The retardation film according to the present embodiment may contain fine particles. The fine particles include an inorganic compound or an organic compound. Examples of the inorganic compound include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate do. Examples of the organic compound include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acryl styrene resin, silicone resin, A pulverized product of an organic polymer compound such as polyvinylidene fluoride resin, polyvinylidene fluoride resin, polyvinylidene fluoride resin, polyvinylidene fluoride resin, Nat resin, benzoguanamine resin, melamine resin, polyolefin resin powder, polyester resin, polyamide resin, polyimide resin, A polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray drying method, a dispersion method, or the like.

The fine particles may be composed of a compound (preferably silicon dioxide) containing silicon in that the haze of the resulting film can be kept low.

Examples of fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (manufactured by Nippon Aerosil Co., Ltd.).

Examples of the zirconium oxide fine particles include Aerosil R976 and R811 (above, manufactured by Nippon Aerosil Co., Ltd.) and the like.

Examples of the resin of the polymer fine particles include a silicone resin, a fluororesin, a (meth) acrylic resin and the like, preferably a silicone resin, more preferably a silicone resin having a three-dimensional network structure. Examples of such a silicone resin include Tosepile 103 and Tosho 105), copper 108, copper 120, copper 145, copper 3120 and copper 240 (manufactured by Toshiba Silicone Co., Ltd.).

Above all, Aerosil 200V and Aerosil R972V are particularly preferable because they can increase the slidability of the film surface while keeping the haze of the retardation film low.

The average particle diameter of the primary particles of the fine particles is preferably 5 to 400 nm, more preferably 10 to 300 nm. The fine particles may form a secondary aggregate mainly having a particle diameter of 0.05 to 0.3 mu m. If the average particle size of the fine particles is 100 to 400 nm, they may exist as primary particles without aggregation.

It is preferable to contain fine particles so that the coefficient of dynamic friction of at least one surface of the retardation film is 0.2 to 1.0. The content of the fine particles is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass with respect to the thermoplastic resin.

In addition, the retardation film according to the present embodiment may further contain a dispersant in order to enhance the dispersibility of the fine particles. The dispersant is one or more selected from amine dispersants and carboxyl group-containing polymer dispersants.

The amine-based dispersant is preferably an amine salt of an alkylamine or polycarboxylic acid, and specific examples thereof include a polyester acid, a polyetherester acid, a fatty acid, a fatty acid amide, a polycarboxylic acid, an alkylene oxide, Dioxane fatty acid ester, polyoxyethylene glycerin fatty acid ester, and the like. Examples of amine salts include amide amine salts, aliphatic amine salts, aromatic amine salts, alkanolamine salts, polyvalent amine salts and the like.

Specific examples of the amine-based dispersant include polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, tripropylamine, diethylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, and the like. Examples of commercially available products include Sol Sparse series (manufactured by Lubrizol Corporation), Ajisuper series (manufactured by Ajinomoto), BYK series (manufactured by Big Chemical), and EFKA series (manufactured by EFKA).

The carboxyl group-containing polymeric dispersant is preferably a polycarboxylic acid or a salt thereof, and may be polycarboxylic acid, ammonium polycarboxylate, sodium polycarboxylate, or the like. Specific examples of the carboxyl group-containing polymer dispersant include polyacrylic acid, ammonium polyacrylate, sodium polyacrylate, ammonium polyacrylate copolymer, polymaleic acid, ammonium polymaleate, sodium polymaleate and the like.

The amine dispersing agent or the carboxyl group-containing polymer dispersing agent may be dissolved in a solvent component or may be commercially available.

The content of the dispersing agent varies depending on the kind of the dispersing agent and the like, but is preferably 0.2 mass% or more with respect to the fine particles. When the content of the dispersant is less than 0.2 mass% with respect to the fine particles, the dispersibility of the fine particles can not be sufficiently increased.

In the case where the retardation film according to the present embodiment further contains a surfactant or the like, the adsorption of the dispersant to the surface of the fine particles is less likely to occur than the surfactant, and the fine particles may easily re-aggregate easily. Since the dispersant is expensive, its content is preferably as small as possible. On the other hand, if the content of the dispersing agent is too small, wetting of the fine particles is liable to occur and dispersion stability tends to be lowered. Therefore, when the optical film of the present invention further contains a surfactant or the like, the content of the dispersant may be about 0.05 to 10 parts by weight based on 10 parts by weight of the fine particles.

The thickness of the retardation film is preferably 80 占 퐉 or less, more preferably 60 占 퐉 or less, and even more preferably 40 占 퐉 or less. On the other hand, the thickness of the retardation film is preferably 10 占 퐉 or more, and more preferably 20 占 퐉 or more, in order to develop a film strength or phase difference of a certain level or more. When the thickness of the retardation film is within this range, it is preferable from the viewpoint of thinning of display device and productivity.

In the present embodiment, in order to adjust the thickness of the retardation film to an appropriate range, the degree of orientation (Spol) of the cellulose acylate resin and the degree of orientation (Sa) of the additive may be within the above range. In particular, the degree of orientation (Sa) of the additive may be within the above range. When Spol and Sa are within the above range, the in-plane retardation value (Ro) easily develops, so that a retardation film having a? / 4 retardation can be produced even if the retardation film is thin.

The haze (total haze) of the retardation film is preferably less than 1%, more preferably 0.5% or less, and most preferably 0.2% or less. When the haze is within this range, the transparency of the film is good, and the retardation film can sufficiently function.

The haze can be adjusted depending on the total carbon number of the acyl group per glucose unit of the cellulose acylate resin contained in the retardation film, as described above. Specifically, it is preferable to use a cellulose acylate resin in which the total number of carbon atoms of an acyl group per one glucose unit is 6.5 or less, from the viewpoint of haze. It can also be adjusted by the additive contained in the retardation film. It is preferable to use an additive represented by the formula (A) and having an SP value of 16 to 23 obtained by the bicerano method from the viewpoint of haze.

The haze (total haze) of the retardation film can be measured with a haze meter (NDH-2000 manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K-7136. The light source of the haze meter may be a halogen electrode of 5 V 9 W, and the light receiving unit may be a silicon photocell (equipped with a non-visible sensitivity filter). The haze can be measured under conditions of 23 캜 and 55% RH.

The visible light transmittance of the retardation film is preferably 90% or more, more preferably 93% or more.

The? / 4 retardation film according to the present embodiment can be applied to optical films of image display devices such as organic EL display devices and liquid crystal display devices; Specifically, it is used as a polarizing plate protective film, an optical compensation film, an antireflection film and the like.

Further, the? / 4 retardation film according to the present embodiment is preferably used as a circularly polarizing plate after bonding with a polarizer (linearly polarizing film).

(Production method of retardation film)

Next, a method for producing the above-mentioned retardation film (? / 4 retardation film) will be described.

The retardation film according to the present embodiment can be formed by a known method. Hereinafter, representative solution casting methods and melt casting methods will be described.

(Solution softening method)

The retardation film according to the present embodiment can be produced by the solution softening method. In the solution casting method, a process of preparing a dope by heating and dissolving a cellulose acylate resin and an additive in an organic solvent, a process of forming a dope on a belt-shaped or drum-shaped metal substrate, a process of drying a flexible dope as a web , A step of peeling from the metal support, a step of stretching or shrinking the peeled web, a step of drying, a step of winding the finished film, and the like.

(Dope production process)

In the dope producing process, the cellulose acylate resin in the dope is preferable because the drying load after the high concentration of the cellulose acylate resin is flexible to the metal support can be reduced. However, if the concentration of the cellulose acylate resin is too high, Precision is getting worse. Therefore, the concentrations compatible therewith are preferably in the range of 10 to 35 mass%, and more preferably in the range of 15 to 25 mass%.

Further, the dope includes a component constituting the retardation film and a solvent. Examples of the solvent include a solvent capable of dissolving a cellulose acylate resin. Specifically, examples thereof include organic solvents such as chlorine-based organic solvents and non-chlorine-based organic solvents.

As the chlorine-based organic solvent, methylene chloride (methylene chloride) can be mentioned. Examples of the non-chlorine-based organic solvent include methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, , 2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro Methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane And the like. From the viewpoint of recent environmental problems, non-chlorine-based organic solvents are preferably used.

When these organic solvents are used for the cellulose acylate resin, it is preferable to reduce the amount of the insolubles by a known dissolving method such as a dissolving method at room temperature, a high-temperature dissolving method, a cooling dissolving method, and a high-pressure dissolving method . As the cellulose acylate resin, methylene chloride may be used, but methyl acetate, ethyl acetate and acetone are preferably used, and among them, methyl acetate is particularly preferable.

In the present specification, an organic solvent having a good solubility in the cellulose acylate resin is referred to as a two-solvent, and an organic solvent exhibiting a major effect on dissolution and used in a large amount is used as a main (organic) solvent or a main ) Solvent.

The dope used in the film formation of the retardation film according to the present embodiment preferably contains an alcohol having 1 to 4 carbon atoms in the range of 1 to 40 mass% in addition to the organic solvent. Such alcohols are obtained by softening the dope on a metal support, evaporation of the organic solvent is started, and when the relative proportion of the alcohol component is increased, the dope film (web) becomes gelled to strengthen the web and peel off from the metal support And when the ratio of the alcohol is low, it also has a role of promoting the dissolution of the cellulose acylate resin of the non-chlorine-based organic solvent.

Examples of alcohols having a carbon number in the range of 1 to 4 include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Of these, ethanol is preferably used from the viewpoints of excellent dope stability, relatively low boiling point, and good drying property. These alcohols do not have solubility in the cellulose acylate resin alone, and thus they are classified as poor solvents.

It is preferable to adjust the DOP viscosity within the range of 100 to 500 Pa · s from the viewpoint of obtaining an excellent film surface quality.

(Flexible process)

In the casting process, the metal support to be used is preferably a mirror-finished surface, and a stainless steel belt or a casting finish drum is preferably used.

The width of the cast is preferably in the range of 1 to 4 m. The surface temperature of the metal support of the flexible process is appropriately selected and set in the range of -50 DEG C to a temperature at which the solvent does not foam by boiling. A higher temperature is preferable because it can speed up the drying speed of the web. However, if the temperature is excessively high, the web may foam and the flatness may deteriorate. The preferred support temperature is appropriately determined within the range of 0 to 100 占 폚. A temperature range of 5 to 30 占 폚 is more preferable. Further, the web can be gelled by cooling to peel off the drum in a state containing a large amount of residual solvent. A method of controlling the temperature of the metal support is not particularly limited, but there is a method of blowing warm air or cold air, or a method of bringing hot water into contact with the metal support. The method of using hot water is preferable because heat is efficiently transferred and the time until the temperature of the metal support becomes constant is short. In the case of using warm air, in consideration of the temperature drop of the web due to the latent heat of evaporation of the solvent, winds at a temperature higher than the desired temperature may be used while preventing warming of the solvent while using warm air above the boiling point of the solvent. Particularly, it is preferable to change the temperature of the support and the temperature of the drying wind during the period from the softening to the peeling, thereby efficiently performing drying.

In order for the? / 4 retardation film to exhibit good planarity, the amount of the residual solvent when peeling the web from the metal support is preferably set within a range of 10 to 150 mass%, more preferably 20 to 40 mass% Or 60 to 130 mass%, more preferably 20 to 30 mass% or 70 to 120 mass%.

In this specification, the amount of the residual solvent is defined by the following formula.

Amount of residual solvent (mass%) = {(M-N) / N} 100

(Wherein M is the mass of the sample taken from the web or film at any time during or after the production, and N is the mass after heating the M at 115 DEG C for 1 hour)

(Drying step)

In the drying step, the web is preferably peeled from the metal support and dried, so that the residual solvent amount is preferably 1.0 mass% or less, more preferably 0 to 0.01 mass%.

In the drying step, a roller drying method is employed, for example, a method in which a web is alternately passed through a plurality of rollers arranged in a vertical direction and then dried, or a method in which a web is conveyed in a tenter method is used.

(Drawing step)

As described above, the? / 4 retardation film of the present embodiment preferably has an in-plane retardation Ro550 of 115 to 160 nm measured at a wavelength of 550 nm, and this retardation can be imparted by stretching the film.

The stretching method is not particularly limited. For example, there are a method of longitudinally stretching a plurality of rollers with a main speed difference therebetween using a roller speed difference, a method of fixing both ends of the web with clips or pins, A method of stretching in the longitudinal direction by extending the interval of the fins in the longitudinal direction, a method of stretching in the transverse direction by extending in the transverse direction, or a method of stretching in both longitudinal and lateral directions and stretching in both the longitudinal and transverse direction can be employed singly or in combination . That is, the film may be stretched in the transverse direction, the longitudinal direction, or both directions with respect to the film formation direction, or may be simultaneous stretching or sequential stretching in the case of stretching in both directions. In the case of the so-called tenter system, it is preferable to drive the clip portion by the linear drive method, since the smooth drawing can be performed, and the risk of breakage can be reduced.

In the stretching process, the stretching process is often performed in the transverse direction (TD direction) and shrinking in the transport direction (MD direction). When the film is shrunk, the main chain direction is easily aligned when transported in the oblique direction. Big. The shrinkage ratio can be determined according to the angle at which the sheet is conveyed.

Fig. 1 is a schematic diagram for explaining the contraction magnification in oblique stretching. Fig. In Fig. 1, when the cellulose acylate film (F) is obliquely stretched in the direction of the reference numeral 112, the long axis M _{1 in the} transport direction is warped and contracted to M ₂ . At this time, the shrinkage percentage (%) is

Shrinkage _{(%) = (M 1 -M} 2) / M1 × 100

Lt; / RTI &gt; If the bending angle is?

M ₂ = M ₁ sin (? -?)

And the shrinkage percentage is,

Shrinkage percentage (%) = (1-sin (? -?)) 100

.

1, reference numeral 111 denotes a stretching direction (TD direction), 113 denotes a transport direction (MD direction), and 114 denotes a slow axis.

Considering the productivity of the long circularly polarizing plate, the? / 4 retardation film according to the present embodiment can be joined to the polarizing film by roll-to-roll bonding with an orientation angle of 45 ° ± 2 ° with respect to the conveying direction desirable.

(Elongation by a warp stretching device)

Next, the oblique stretching method of stretching in the direction of 45 DEG will be further described. In the method of producing the? / 4 retardation film according to the present embodiment, it is preferable to use an oblique stretching device as a method for imparting the oblique orientation to the stretched cellulose acylate film.

As the oblique stretching device applicable to the present embodiment, it is possible to freely set the orientation angle of the film by variously changing the rail pattern, and it is possible to align the orientation axis of the film horizontally and evenly with high precision over the film width direction, It is preferable that the film stretching device is capable of controlling the thickness and the retardation of the road film.

Fig. 2 is a schematic view showing an example of a rail pattern of an oblique drawing apparatus applicable to manufacture of a? / 4 retardation film according to the present embodiment. The drawing shown here is only an example, and the drawing apparatus applicable in the present embodiment is not limited to this.

In general, in the oblique drawing apparatus, as shown in Fig. 2, the unwinding direction D1 of the long film fabric is different from the winding direction D2 of the drawn film after stretching, and forms the unwinding angle? I have. The unwinding angle [theta] i can be arbitrarily set to a desired angle in a range exceeding 0 [deg.] And less than 90 [deg.]. In this specification, the term "long" refers to a film having a length of at least 5 times or more, preferably 10 times or more, with respect to the width of the film.

Both ends of the long film fabric are gripped by the right and left grip members (tenters) at the entrance of the oblique stretching device (position A in the figure), and travel along with the running of the grip members. The right and left gripping members are provided on the left and right gripping members Ci and Co opposed to each other in the direction substantially perpendicular to the advancing direction of the film (the pulling-out direction D1) at the entrance of the oblique stretching device (position A in the drawing) Travels on the left and right asymmetrical rails Ri and Ro and releases the film held by the tenter at the position (B position in the drawing) at the end of the stretching.

At this time, as the left and right gripping members opposed to each other at the entrance of the oblique drawing device (position A in the drawing) travel on the left and right asymmetrical rails Ri and Ro, the gripping member Ci, The position of the gripping member Co running on the Ro side becomes a positional relationship.

That is, the gripping members (Ci, Co), which were opposed to each other in the direction substantially perpendicular to the unwinding direction (D1) of the film, at the entrance of the oblique drawing device (gripping start position by the gripping member of the film) The straight line connecting the holding members Ci and Co is inclined at an angle? L with respect to a direction substantially perpendicular to the winding direction D2 of the film.

According to the above method, the film material is obliquely stretched so that the orientation angle becomes? L, and a retardation film is obtained. The term &quot; substantially perpendicular &quot;

More specifically, in the method of producing the? / 4 retardation film of the present embodiment, it is preferable that oblique stretching is performed using the obliquely stretchable tenter described above.

This stretching apparatus is a device for obliquely stretching a film raw material by heating it to an arbitrary stretchable temperature. This stretching device is provided with a heating zone, a pair of rails on the right and left where the gripping members for transporting the film run, and a plurality of gripping members running on the rails. Both ends of a film sequentially fed to the inlet of the stretching device are gripped by a gripping member to guide the film in the heating zone and the film is released from the gripping member at the outlet of the stretching device. The film opened from the gripping member is wound on the winding core. Each of the pair of rails has a continuous trajectory of an endless shape, and the gripping member, which has opened the holding of the film at the outlet of the stretching device, travels outside and is returned to the sequentially arriving portion.

Further, the rail pattern of the stretching device has a shape which is asymmetrical to the left and right, and the rail pattern can be adjusted manually or automatically depending on an orientation angle, a stretching magnification, etc. given to a long stretched film to be produced. In the oblique drawing apparatus used in the present embodiment, it is preferable that the positions of the rail portions and the rail connecting portions are freely set so that the rail pattern can be arbitrarily changed (circle in Fig. 2 shows one example of the connecting portion).

In the present embodiment, the gripping members of the stretching device are kept at a constant distance from the gripping members at the front and rear, and travel at a constant speed. The running speed of the gripping member can be appropriately selected, but is usually 1 to 100 m / min. The difference in running speed of the pair of right and left gripping members is usually 1% or less, preferably 0.5% or less, more preferably 0.1% or less of the running speed. This is because, if there is a difference in traveling speed between the left and right sides of the film at the exit of the stretching process, wrinkles or slanting occur at the exit of the stretching process, and therefore the speed difference between the right and left gripping members is required to be substantially the same. In a general stretching device or the like, there is a speed variation occurring on the order of seconds or less depending on the period of the sprocket for driving the chain, the frequency of the drive motor, and the like, often causing several percent of unevenness. This does not apply to the speed difference.

In the stretching apparatus according to the present embodiment, a large bending rate is often required for rails that regulate the locus of the gripping member, particularly at the portion where the film is slanted. It is preferable that the locus of the gripping member is curved at the bent portion in order to avoid interference between the gripping members due to abrupt bending or local concentration of stress.

In this embodiment, both ends of the long film material are sequentially gripped by the right and left gripping members at the entrance of the oblique stretching device (position A in the figure), and travel along with the running of the gripping member. At the entrance of the oblique stretching device (position A in the figure), the left and right gripping members, which are opposed to each other in the direction substantially perpendicular to the film advancing direction (releasing direction D1), travel in a left- A heating zone having a zone, an elongation zone, and a heat fixing zone.

The preheating zone refers to a section in which the gripping members gripped at both ends of the heating zone inlet portion travel while maintaining a constant gap.

The stretching zone refers to a section from the beginning of separation of the gripping members holding the both ends to a predetermined interval. In the stretching zone, the oblique stretching as described above is carried out. If necessary, stretching may be performed in the longitudinal direction or the transverse direction before and after the oblique stretching. In the case of oblique stretching, contraction is caused in the MD direction (the direction of the forward phase axis), which is the direction perpendicular to the slow axis at the time of bending.

In the? / 4 retardation film according to the present embodiment, the stretching treatment is followed by a shrinking treatment to remove the optical adjusting agent (for example, the cellulose acylate represented by the above formula (A)) from the main chain of the cellulose acylate Compound) is shrunk in a direction perpendicular to the stretching direction (fast axis direction), whereby the alignment state of the optical adjusting agent is rotated so that the main axis of the optical adjusting agent can be aligned with the main chain of the cellulose acylate as the matrix resin. As a result, it is possible to increase the refractive index (ny ₂₈₀ ) in the fast axis direction at 280 nm in the ultraviolet ray region, and the gradient of the ny ultraviolet wavelength dispersion in the visible light region can be made steep.

The heat fixing zone refers to a section in which the gripping members at both ends run parallel to each other in a period in which the interval of the gripping members after the stretching zone becomes constant again. After passing through the heat fixing zone, the temperature in the zone may pass through a section (cooling zone) where the temperature is set to be equal to or lower than the glass transition temperature (Tg) of the thermoplastic resin constituting the film. At this time, in consideration of shrinkage of the film due to cooling, a rail pattern may be used in which the interval between the holding members facing each other is narrowed.

The temperature of each zone is preferably in the range of Tg to Tg + 30 占 폚, the temperature of the stretching zone in the range of Tg to Tg + 30 占 폚, the glass transition temperature (Tg) of the thermoplastic resin, The temperature of the cooling zone is preferably set within the range of Tg-30 DEG C to Tg.

Further, in order to control the thickness unevenness in the width direction, the temperature difference in the width direction in the stretching zone may be set. In order to set the temperature difference in the width direction in the stretching zone, there is a method in which the opening degree of the nozzle for sending warm air into the constant temperature chamber is adjusted to be different in the width direction or a known method such as heating control in which the heater is arranged in the width direction Can be used.

The length of the preheating zone is usually in the range of 100 to 150% with respect to the length of the stretching zone, and the length of the fixing zone is usually 50 to 100% .

The draw ratio (W / W0) in the drawing step is preferably in the range of 1.3 to 3.0, more preferably in the range of 1.5 to 2.8. When the stretching magnification falls within this range, thickness non-uniformity in the width direction can be reduced. In the stretching zone of the warp stretching apparatus, if the stretching temperature is set to a difference in the width direction, it is possible to further improve the thickness non-uniformity in the width direction. W0 is the width of the film before stretching, and W is the width of the film after stretching.

Examples of the oblique stretching method applicable to the present embodiment include the stretching methods shown in Figs. 3 (a) to 3 (c) and Figs. 4 (a) and 4 (b) in addition to the method shown in Fig.

Fig. 3 is a schematic view showing a method for producing a retardation film according to an embodiment of the present invention (an example in which the film is loosened from a long film roll and then warped) Shows a pattern of stretching. 4 is a schematic view showing a method for producing a retardation film according to an embodiment of the present invention (an example in which an oblique stretching is continuously performed without winding a long film fabric), and a continuous oblique stretching process .

3 and 4, reference numeral 15 denotes an oblique stretching device, 16 denotes a film unwinding device, 17 denotes a transport direction changing device, 18 denotes a winding device, and 19 denotes a film forming device. In each figure, the same reference numerals are sometimes omitted.

The film unwinding device 16 is slidable and pivotable or slidable so as to allow the film to be fed at a predetermined angle with respect to the entrance of the oblique stretching device, It is preferable that the film can be sent to the film forming apparatus. 3 (a) to 3 (c) show patterns in which the arrangements of the film unwinding device 16 and the transport direction changing device 17 are changed, respectively. 4 (a) and 4 (b) show a pattern in which the film formed by the film-forming apparatus 19 is directly unwound to the stretching device. By making the film unwinding device 16 and the conveying direction changing device 17 have such a structure, the width of the entire manufacturing apparatus can be made narrower, and the position and angle of the film can be finely controlled Thus, it becomes possible to obtain a long stretched film having a small deviation of the thickness and the optical value of the film. In addition, by making the film unwinding device 16 and the transport direction changing device 17 movable, it is possible to effectively prevent defective occlusion of the film of the right and left clips.

The winding device 18 can arrange the film at a predetermined angle with respect to the exit of the oblique-stretching device so that the drawing-out position and angle of the film can be finely controlled, and the deviation of the film thickness and optical value It becomes possible to obtain a small long stretched film. As a result, the occurrence of wrinkles of the film can be effectively prevented and the winding-up property of the film is improved, so that the film can be wound up in a long length. In this embodiment, the drawing tension (T) (N / m) of the stretched film is adjusted within a range of 100 N / m <T <300 N / m, preferably 150 N / m <T <250 N / m .

(Melt forming method)

The above-mentioned? / 4 retardation film may be formed by a melt film forming method. The melt film formation method is a molding method in which a composition including a resin and an additive such as a plasticizer is heated and melted to a temperature showing fluidity and then a melt containing a flowable thermoplastic resin is softened.

The molding method for heating and melting can be classified into, for example, a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, and a stretching molding method. Of these molding methods, the melt extrusion method is preferable in terms of mechanical strength and surface precision.

The plurality of raw materials used in the melt extrusion method are usually kneaded and pelletized in advance. The pelletization can be carried out by a known method. For example, dry cellulose acylate, a plasticizer and other additives are fed to an extruder through a feeder, kneaded using a single- or twin-screw extruder, extruded from a die into a strand shape , Followed by water-cooling or air-cooling and cutting.

The additives may be mixed before being supplied to the extruder, or they may be supplied to individual feeders. Further, it is preferable that small amounts of additives such as fine particles and antioxidants are mixed in advance in order to mix them uniformly.

The extruder used for the pelletization is preferably a method in which pelletization is possible and processing is carried out at a low temperature as possible so as to suppress the shear force and prevent deterioration of the resin (decrease in molecular weight, coloration, gel formation, etc.). For example, in the case of a twin-screw extruder, it is preferable to use a deep groove-type screw to rotate in the same direction. In terms of kneading uniformity, an engaging type is preferable.

Film formation is carried out using the pellets obtained as described above. Of course, it is also possible to feed the powder of the raw material directly to the feeder and supply it to the extruder without melting into the pellet.

The above pellets are filtered using a leaf disc type filter or the like with a melting temperature in the range of 200 to 300 캜 by using a uniaxial or biaxial type extruder, So that the film is nipped by the cooling roller and the elastic touch roller, and solidified on the cooling roller.

In the case of introduction into the extruder from the feed hopper, it is preferable to carry out under vacuum or under reduced pressure or in an inert gas atmosphere to prevent oxidative decomposition or the like.

The extrusion flow rate is preferably stably performed by introducing a gear pump. In addition, a stainless steel fiber sintered filter is preferably used as the filter used for removing the foreign matter. The stainless steel fiber sintering filter is obtained by forming a state of intricately entangling a stainless steel fiber body, compressing it, and sintering the contact portion to integrate the filter. The filtration accuracy can be adjusted by changing the density depending on the thickness and the amount of compression of the fiber.

Additives such as a plasticizer and fine particles may be mixed with a resin in advance or may be mixed in the middle of an extruder. In order to uniformly add it, it is preferable to use a mixing device such as a static mixer.

It is preferable that the film temperature on the touch roller side when the film is nipped by the cooling roller and the elastic touch roller is within the range of Tg to Tg + 110 deg. A known elastic touch roller can be used as the elastic touch roller having an elastic surface used for this purpose. The elastic touch roller is also referred to as a nip pressure roller, and a commercially available elastic pressure roller may be used.

When the film is peeled from the chill roller, it is preferable to control the tensile force to prevent deformation of the film.

The film obtained as described above can be subjected to stretching and shrinking treatment by a stretching operation after passing through a process in contact with a cooling roller. As the method of stretching and shrinking, a known roller stretching device or a warp stretching device as described above can be preferably used. The stretching temperature is preferably in the range of Tg to Tg + 60 占 폚 of the resin constituting the film.

Prior to winding, the end portion may be slit and cut with a width to become a product, and knurling (embossing) may be performed at both ends in order to prevent adhesion and scratches during winding. The knurling process can be performed by heating or pressurizing a metal ring having a concavo-convex pattern on its side surface. In addition, the gripping portions of the clips at both ends of the film are usually cut off because they are deformed and can not be used as a product.

The above-mentioned? / 4 retardation film can be formed as a circularly polarizing plate by laminating the retardation film so that the angle between the slow axis and the transmission axis of the polarizer described later becomes substantially 45 degrees. In this specification, &quot; substantially 45 DEG &quot; means that it is within a range of 40 to 50 DEG.

The angle between the in-plane slow axis of the? / 4 retardation film and the transmission axis of the polarizer is preferably in the range of 41 to 49 degrees, more preferably in the range of 42 to 48 degrees, more preferably in the range of 43 to 47 degrees More preferably within the range of 44 to 46 [deg.].

<Circular Polarizer>

The circular polarizer (long circular polarizer) according to this embodiment is manufactured by cutting a long roll having a long protective film, a long polarizer and a long λ / 4 phase difference film in this order. Since the long circularly polarizing plate according to the present embodiment is manufactured by using the above-mentioned? / 4 retardation film, it can be applied to an organic EL display or the like to be described later so that the mirror surface reflection of the metal electrode of the organic EL element can be suppressed Shielding effect can be exhibited. As a result, it is possible to prevent reflection at the time of observation and improve the black color expression.

It is also preferable that the long circularly polarizing plate is provided with an ultraviolet ray absorbing function. When the protective film on the viewer side is provided with an ultraviolet ray absorbing function, it is preferable from the viewpoint that a protective effect against ultraviolet rays can be exhibited on both the polarizer and the organic EL element. When the? / 4 retardation film on the light-emitting side also has an ultraviolet ray absorbing function, deterioration of the organic EL element can be suppressed more in the case of using it in an organic EL display to be described later.

Further, the long circularly polarizing plate according to the present embodiment uses the above-mentioned? / 4 retardation film adjusted so that the angle of the slow axis (that is, the orientation angle) becomes "substantially 45 °" with respect to the long direction, The adhesive layer can be formed and the polarizing film can be bonded to the? / 4 phase difference film plate. Concretely, it is possible to incorporate a step of bonding the polarizing film and the? / 4 phase difference film during the drying step or the drying step, which is performed after the step of drawing the polarizing film is completed, And can be connected to a consistent production line in the next step by winding in rolls after bonding. Further, when the polarizing film and the? / 4 retardation film are bonded to each other, the protective film may be supplied in a roll state at the same time to be continuously bonded. From the viewpoints of performance and production efficiency, it is preferable to simultaneously bond the? / 4 retardation film and the protective film to the polarizing film. That is, after the step of forming the polarizing film is completed, the protective film and the? / 4 retardation film are bonded to the both sides of the polarizing film during the drying step or the drying step, Can be obtained.

In the long circularly polarizing plate according to the present embodiment, it is preferable that the polarizer is sandwiched by the above-mentioned? / 4 retardation film and the protective film, and a cured layer is preferably laminated on the visual side of the protective film.

&Lt; Organic EL display &

The image display apparatus according to the present embodiment, for example, an organic EL display (organic EL image display apparatus) is manufactured using the long circularly polarizing plate. More specifically, the organic EL display according to the present embodiment includes a long circularly polarizing plate using the above-mentioned? / 4 retardation film and an organic EL element. The screen size of the organic EL display is not particularly limited, and may be 20 inches or more.

Fig. 5 is a schematic explanatory view of the configuration of the organic EL display of the present embodiment. Fig. The configuration of the organic EL display of the present embodiment is not limited to that shown in Fig. 5 at all.

5, a metal electrode 2, a TFT 3, an organic luminescent layer 4, a transparent electrode (ITO or the like) 5, an insulating layer 5, and an insulating layer 6 are sequentially formed on a transparent substrate 1 using glass, polyimide, Retardation film 9 and the protective film 11 are laminated on the organic EL element B having the layer 6, the sealing layer 7 and the film 8 (not shown) (C) sandwiched and supported by the organic EL display (A). The protective film 11 is preferably laminated with a cured layer 12. The cured layer 12 not only prevents scratches on the surface of the organic EL display but also has an effect of preventing warping by the long circularly polarizing plate. The antireflection layer 13 may be provided on the cured layer. The thickness of the organic EL device itself is about 1 mu m.

In general, in an organic EL display, a metal electrode, an organic light emitting layer, and a transparent electrode are sequentially laminated on a transparent substrate to form a light emitting element (organic EL element). Here, the organic luminescent layer is a laminate of various organic thin films, for example, a laminate of a hole injecting layer containing a triphenylamine derivative or the like and a luminescent layer containing a fluorescent organic solid such as anthracene, A multilayer structure of an electron injection layer including a perylene derivative or the like, or a multilayer structure of a hole injection layer, a light emission layer, and an electron injection layer of these layers.

In the organic EL display, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and energy generated by recombination of the holes and electrons excites the fluorescent material, And emits light when it returns to the state. The mechanism of recombination on the way is the same as that of a common diode. As can be expected from this, the current and the light emission intensity exhibit strong nonlinearity accompanied by rectification with respect to the applied voltage.

In the organic EL display, in order to extract light from the organic light emitting layer, at least one of the electrodes needs to be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is preferably used as the anode . On the other hand, it is important to use a material having a small work function for the cathode in order to facilitate the injection of electrons and improve the luminous efficiency, and metal electrodes such as Mg-Ag and Al-Li are generally used.

The long circularly polarizing plate having the? / 4 retardation film can employ an organic EL display including a large screen having a screen size of 20 inches or more, that is, a diagonal distance of 50.8 cm or more.

In the organic EL display having such a structure, the organic light emitting layer is formed of a very thin film with a thickness of about 10 nm. As a result, the organic light emitting layer almost completely transmits the light, like the transparent electrode. As a result, the light incident on the surface of the transparent substrate at the time of non-light emission, the light transmitted through the transparent electrode and the organic light emitting layer and reflected by the metal electrode comes back to the surface side of the transparent substrate. The display surface looks like a mirror.

An organic EL display comprising an organic EL element having a transparent electrode on a surface side of an organic light emitting layer emitting light upon application of a voltage and a metal electrode on a back surface side of the organic light emitting layer, (Viewer side), and a retardation film can be provided between these transparent electrodes and the polarizing plate.

The retardation film and the polarizing plate have the effect of preventing the mirror surface of the metal electrode from being visually recognized from the outside due to the polarizing action since the polarizing plate has the function of polarizing the light reflected from the metal electrode after being incident from the outside. Particularly, when the phase difference film is made of a? / 4 phase difference film and the angle formed by the polarizing direction of the polarizing plate and the polarization direction of the retardation film is adjusted to? / 4, the mirror surface of the metal electrode can be completely shielded.

That is, only the linearly polarized light component is transmitted through the polarizing plate by external light incident on the organic EL display, and the linearly polarized light is generally elliptically polarized by the retardation plate. Particularly, the retardation film is a? / 4 retardation film When the angle formed by the polarizing direction of the polarizing plate and the retardation film is π / 4, it becomes circularly polarized light.

The circularly polarized light is transmitted through the transparent substrate, the transparent electrode and the organic thin film, reflected by the metal electrode, again transmitted through the organic thin film, the transparent electrode and the transparent substrate, and becomes linearly polarized again in the retardation film. The linearly polarized light is orthogonal to the polarization direction of the polarizing plate, and thus can not transmit through the polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

The present specification discloses various types of techniques as described above, of which the main techniques are summarized below.

One aspect of the present invention is a cellulose acylate resin and a long shape retardation film comprising an additive, wherein the additive is an additive represented by the following formula (A), and the cellulose acylate resin Is in the range of 0.03 or more and 0.15 or less and the degree of orientation of the additive calculated by the light absorption spectroscopy method is larger than 0.15 and the in-plane retardation value of the retardation film at a wavelength of 550 nm is 115 nm or more and 160 nm or less, Wherein an angle formed between the in-plane slow axis of the retardation film and the longitudinal direction of the retardation film is not less than 15 ° and not more than 85 °.

In the formula (A), Q represents an aromatic hydrocarbon ring, a non-aromatic hydrocarbon ring, an aromatic heterocyclic ring, or a non-aromatic heterocyclic ring, and W a and W b represent a hydrogen atom bonded to an atom constituting the ring of Q An atom or a substituent, the atom to which Wa binds and the atom to which Wb is bonded are adjacent to each other in the ring of Q, the Wa and Wb are different from each other, and the Wa and Wb form a ring number and, R ¹ and R ² are, each independently represents a substituent, R ³ is represents a substituent, substitution degree m is from 0 to 2, and when m is 2, two R ³ are same or another An alkylene group, an alkenylene group, an alkynylene group, an -O- group, a - (C = O) group, and a degree of polymerization (n) of 1 to 10; and L ¹ and L ² each independently represent a single bond, O) - group, - (C = O) -O- group, -NR _L - group, -S- group, - (O = S = O ) - group and _{- (C = O) -NR L} - consisting of an Bivalent kites selected from the group Group, or represents a combination thereof, R _L in the L ¹ and L ² represents a hydrogen atom or a substituent.

According to such a constitution, even in the case of a cellulose acylate film having a sufficiently thin thickness, the retardation of brittleness can be sufficiently suppressed, and the in-plane retardation of the light having a good transparency and a wide range of visible light wavelength is about 1/4 A retardation film can be provided. Further, when this retardation film is applied to an image display apparatus such as an organic EL display, an image display apparatus capable of sufficiently suppressing reflection of external light and displaying a good image can be obtained.

In the retardation film, it is preferable that the total number of carbon atoms of the acyl group per glucose unit of the cellulose acylate resin is 6.5 or less.

According to such a constitution, a retardation film having better transparency can be obtained.

The in-plane retardation value (Ro) 450 at a wavelength of 450 nm, the in-plane retardation value (Ro) at a wavelength of 550 nm (Ro) 550 of the retardation film, It is preferable that the retardation value (Ro) 650 of the retardation film satisfies the following formulas (1) and (2).

0.72? Ro (450) / Ro (550)? 0.94 (One)

0.83? Ro (550) / Ro (650)? 0.98 (2)

With such a configuration, a phase difference film having an in-plane retardation of about 1/4 of the wavelength can be obtained for light in a wider range of the visible light wavelength.

In the retardation film, the total degree of substitution of the acyl group per glucose unit of the cellulose acylate resin is preferably 1.5 or more and 2.5 or less.

According to this structure, it is possible to provide a retardation film whose in-plane retardation is about ¼ of the wavelength with respect to light having a thinner thickness and a wider visible light wavelength.

Another aspect of the present invention is a circularly polarizing plate having the retardation film.

According to such a constitution, a circular polarizer that is sufficiently thin and can fully exhibit its antireflection capability can be obtained.

According to another aspect of the present invention, there is provided an image display apparatus including the retardation film.

According to such a configuration, an image display device capable of sufficiently displaying an image with sufficiently suppressed reflection of external light and the like can be obtained.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. In the examples, &quot; part &quot; or &quot;% &quot; indicates &quot; part by mass &quot; or &quot;% by mass &quot;

Example

[Cellulose Acylate Resin]

First, the resin (cellulose acylate resin) used in this embodiment will be described.

As the cellulose acylate resin, those having substitution degrees of acyl groups shown in Table 11 (cellulose acylate resins 1 to 5) were used.

[additive]

Next, the additive used in this embodiment will be described.

Additive 1: The compound represented by the following formula (Compound No. 62)

Additive 2: Compound represented by the following formula (Compound No. 63)

Additive 3: Compound (Compound No. 64) represented by the following formula:

Additive 4: Compound represented by the following formula (Compound No. 11)

[Plasticizer]

Next, the plasticizer used in this embodiment will be described.

Plasticizer 1: Compound represented by the following formula

Ester ester compound A

Plasticizer 2: Triphenylphosphate (TPP)

Plasticizer 3: Biphenyl diphenyl phosphate (BDP)

[Example 1]

(Production of fine particle addition liquid)

The particulate addition liquid to be added to the dope will be described.

First, 11 parts by mass of fine particles (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.) and 89 parts by mass of ethanol were mixed with a dissolver for 50 minutes and then dispersed using a Manton-Gaulin disperser to obtain fine particles To prepare a dispersion.

Then, 50 parts by mass of methylene chloride was added to the dissolution tank, and 50 parts by mass of the prepared fine particle dispersion was added slowly while methylene chloride was sufficiently stirred. Further, the secondary particles were dispersed in the attritor so that the particle diameter thereof was 0.01 to 1.0 mu m. The solution was filtered with Fine Mat NF (manufactured by Nippon Seisen Co., Ltd.) to prepare a fine particle addition liquid.

(Preparation of Dope)

First, methylene chloride and ethanol as organic solvents were added to the pressure melting tank in an amount shown below. The following cellulose acylate resin was added to a pressurized dissolution tank containing an organic solvent with stirring. This was heated and completely dissolved with stirring, and this was filtered using Azumi-rosy No.244 manufactured by Azumi Co., Ltd. to prepare a main dope. Subsequently, the additive 1, the plasticizer 1 and the fine particle addition liquid prepared as described above were introduced into a main melting furnace as a compound represented by the general formula (A) and sealed, followed by dissolution with stirring to prepare a dope .

<Composition of Dope>

Methylene chloride 340 parts by mass

ethanol 64 parts by mass

Cellulose Acylate Resin 1 100 parts by mass

Additive 1 4 parts by mass

Plasticizer 1 5 parts by mass

The particulate additive liquid 1 part by mass

(Film forming)

The dope prepared as described above was plied on a stainless steel belt support and the solvent was evaporated until the residual solvent amount in the film reached 75% by mass, and then the film was peeled from the stainless belt support with a peel tension of 130 N / m .

The peeled film was uniaxially stretched at a stretching ratio of 1% only in the width direction (TD direction) using a stretching apparatus while heating at 180 占 폚, and the conveying tension was adjusted so as not to shrink in the conveying direction (MD direction) Respectively. The residual solvent at the start of the stretching was 15 mass%.

Subsequently, drying was completed while conveying the drying zone through a plurality of rollers. The drying temperature was 130 占 폚, and the conveying tension was 100 N / m. Thus, a resin film fabric wound in a roll form was produced.

(Drawing step)

A resin film was drawn from this resin film fabric and the resin film was stretched at a stretching temperature of 185 DEG C and a stretching magnification of 1.8 times using an oblique stretching device having the constitution described in Fig. And the oblique stretching was performed by adjusting the bending angle &amp;thetas; and the shrinkage ratio. By doing so, a? / 4 retardation film 1 having a film thickness of 40 μm was produced.

[Example 2]

The? / 4 phase difference film 2 having a film thickness of 39 占 퐉 was obtained in the same manner as in Example 1, except that 4 parts by mass of the plasticizer 2 and 4 parts by mass of the plasticizer 3 were used as the plasticizer and the stretching magnification was changed to 1.9 times. Respectively.

[Example 3]

Retardation film 3 having a film thickness of 32 占 퐉 was obtained in the same manner as in Example 1 except that the cellulose acylate resin 3 was used as the cellulose acylate resin and the stretching temperature was changed to 210 占 폚 and the stretching magnification was changed to 1.5 times. Respectively.

[Example 4]

Retardation film 4 having a film thickness of 22 占 퐉 was obtained in the same manner as in Example 1 except that the cellulose acylate resin 6 was used as the cellulose acylate resin and the stretching temperature was changed to 200 占 폚 and the stretching magnification was changed to 1.4 times. Respectively.

[Example 5]

Except that the cellulose acylate resin 5 was used as the cellulose acylate resin, the additive 4 was used as the additive, and the stretching temperature was changed to 180 占 폚 and the stretching magnification was changed to 1.8 times. Lt; / RTI &gt;

[Example 6]

Except that the cellulose acylate resin 4 was used as the cellulose acylate resin and the additive 4 was used as the additive and the stretching temperature was changed to 175 ° C and the stretch magnification was changed to 1.8 times, Mu] m / 4 retardation film 6 was produced.

[Comparative Example 1]

A? / 4 retardation film 7 having a film thickness of 65 占 퐉 was produced in the same manner as in Example 1 except that the additive 2 was used as an additive and the stretching temperature was changed to 183 占 폚.

[Comparative Example 2]

Cellulose acylate resin 2 was used as the cellulose acylate resin, additive 3 was used as the additive, and 2 parts by mass of the plasticizer and 4 parts by mass of the plasticizer were used as the plasticizer. The stretching temperature was 195 占 폚, the stretching magnification was 2.1 / 4 retardation film 8 having a thickness of 80 mu m was produced in the same manner as in Example 1. [

[Comparative Example 3]

A cellulose acylate resin 2 was used as the cellulose acylate resin, and additive 2 was used as the additive. In addition to the fact that the stretching temperature was changed to 195 占 폚,? / 4 A retardation film 9 was produced.

[Comparative Example 4]

Except that the cellulose acylate resin 2 was used as the cellulose acylate resin, the additive 3 was used as the additive, 17 parts by mass of the plasticizer was added, and the stretching temperature was changed to 190 占 폚 and the stretching magnification to 2.1 times. Similarly, a? / 4 retardation film 10 having a thickness of 85 μm was produced.

[Comparative Example 5]

Retardation film 11 having a film thickness of 32 占 퐉 was obtained in the same manner as in Example 1 except that the cellulose acylate resin 3 was used as the cellulose acylate resin and the stretching temperature was changed to 195 占 폚 and the stretching magnification was changed to 1.4 times. Respectively.

[Comparative Example 6]

Retardation film 12 having a film thickness of 30 占 퐉 was obtained in the same manner as in Example 1 except that the cellulose acylate resin 3 was used as the cellulose acylate resin and the stretching temperature was changed to 210 占 폚 and the stretch magnification was changed to 2.0 times. Respectively.

&Lt; Measurement of each characteristic value of film &

(Degree of orientation (Spol, Sa))

Measuring device

A polarizer (extinction ratio 1 × 10 ^-5 Glan-Taylor prism) corresponding to the ultraviolet region was provided on the light source side of the spectrophotometer V-7100 (manufactured by Nippon Bunko Kogyo Co., Ltd.), and it was confirmed that there was no integral sphere on the detection side , And a commercially available polarizing filter is provided.

How to calculate Sa

Each of the retardation films 1 to 12 prepared in Examples 1 to 6 and Comparative Examples 1 to 6 was installed in the apparatus and the absorption spectrum was measured in a wavelength range of 220 to 450 nm. At this time, a sample was provided so that the slow axis direction of the film coincided with the transmission axis of the polarizer, and the spectrum was measured to obtain the absorbance (Aa) (P) of the absorption from the additive. Also, in the state where the sample was provided so that the slow axis direction of the film was 90 DEG with respect to the transmission axis of the polarizer, the spectrum was similarly measured to obtain the absorbance (Aa) (V) of absorbance derived from the additive.

Using the obtained absorbances Aa (P) and Aa (V), the degree of orientation Sa of the additive was calculated according to the following formula.

Sa (Aa (V) -Aa (P)} / {Aa (V) + 2Aa (P)}

How to calculate Spol

Except that azobenzene was added in place of the additives 1 to 4 of the retardation films 1 to 12 produced in Examples 1 to 6 and Comparative Examples 1 to 6 in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 6 To prepare Spol measurement films 1 'to 12'. Note that the stretching temperature was set so that the difference between the glass transition temperature of each of the retardation films 1 to 12 and the respective stretching temperatures and the difference between the glass transition temperature and the stretching temperature of the films 1 'to 12' The stretching temperatures of 1 'to 12' were set. The prepared Spol measurement film was placed in the spectrophotometer with the polarizer disposed on the light source side as in the case of calculating Sa and the absorbance derived from azobenzene in the direction in which the transmission axis of the polarizer coincided with the slow axis direction of the film Apol) (P) and the absorbance (Apol) (V) at 90 ° tilt.

Using the obtained absorbances Apol (P) and Apol (V), the degree of orientation (Spol) of the cellulose acylate resin is calculated according to the following formula.

Spol = {Apol (V) -Apol (P)} / {Apol (V) + 2Apol (P)

The glass transition temperature (Tg) of the film was measured using a differential scanning calorimeter DSC6220 (SII, manufactured by Nanotechnology Co., Ltd.) as follows.

1) 10.0 mg of the film piece was weighed to 0.01 mg, sealed in an aluminum pan, and set in a sample holder of DSC6220 (SII, manufactured by Nanotechnology Co., Ltd.). As a reference, an empty aluminum fan was used.

2) Temperature control of Heat-Cool-Heat was performed under the conditions of a measurement temperature of 30 to 240 占 폚, a temperature increase rate of 5 占 폚 / min, and a temperature decrease rate of 10 占 폚 / min. Then, the glass transition temperature was determined based on the data in the 2nd heat. Specifically, a tangent line indicating the maximum inclination between the extension line of the base line before the rise of the first endothermic peak and the peak point of the rise end of the first endothermic peak was drawn, and the intersection point was taken as the glass transition temperature (Tg) .

(Retardation value and wavelength dispersion)

The retardation films 1 to 12 produced in Examples 1 to 6 and Comparative Examples 1 to 6 were subjected to measurement at 450 nm, 550 nm and 650 nm using an Axoscan manufactured by Axometrics under the environment of 23 ° C and 55% RH. (450) / Ro (550) were calculated by measuring retardation values (Ro) 450, Ro (550) and Ro (650) in the in- The in-plane orientation angle was also measured using Axoscan manufactured by Axometrics.

The wavelength dispersibility Ro (450) / Ro (550) was evaluated according to the following criteria.

?: 0.81? Ro (450) / Ro (550)? 0.89

?: 0.72? Ro (450) / Ro (550) <0.81, 0.89 <Ro (450) / Ro (550)

: Ro (450) / Ro (550) < 0.72, 0.94 < Ro (450)

The wavelength dispersibility Ro (550) / Ro (650) was evaluated according to the following criteria.

?: 0.85? Ro (550) / Ro (650)? 0.95

?: 0.83? Ro (550) / Ro (650) <0.85, 0.95 <Ro (550) / Ro (650)

Ro: (550) / Ro (650) < 0.83, 0.98 < Ro (550)

(Thickness of film)

The thickness of the film was measured using a commercially available contact type film thickness measuring machine and evaluated according to the following criteria.

?: 20 占 퐉 or more and 40 占 퐉 or less

?: Greater than 40 占 퐉 and not greater than 60 占 퐉

DELTA: larger than 60 mu m and not larger than 80 mu m

×: greater than 80 μm

(Hayes)

The haze (total haze) of the retardation film was measured with a haze meter (NDH-2000 manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K-7136. The light source of the haze meter was a halogen lamp of 5 V 9 W, and the light receiving unit was a silicon photocell (equipped with a non-visible sensitivity filter). The measurement of the haze was carried out under the conditions of 23 캜 and 55% RH.

 Haze was evaluated according to the following criteria.

?: Not more than 0.2%

?: Greater than 0.2% and less than 0.5%

?: Greater than 0.5% and not more than 1.0%

X: greater than 1.0%

(Tear strength)

Under the conditions of 23 ° C. and 55% RH, the tear strength of the Elmendorf method was measured in both directions of the film growth axis direction and the fast axis direction by a light load tearing apparatus manufactured by Toyo Seiki Co., Ltd. according to JIS K 7128-1991 Respectively. The average value of the tearing load in the direction of the slow axis and the tearing load in the fast axis direction of the film was calculated and evaluated according to the following criteria.

O: 40 mN or more

X: Less than 40 mN

(Display characteristic)

The display characteristics were evaluated using the organic EL display using the retardation films 1 to 12 produced in the above-mentioned Examples 1 to 6 and Comparative Examples 1 to 6 as follows.

<Fabrication of long circular polarizer plate>

The polyvinyl alcohol film having a thickness of 120 占 퐉 was uniaxially stretched (temperature: 110 占 폚, stretching magnification: 5 times). This was immersed in an aqueous solution containing 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds and subsequently immersed in an aqueous solution at 68 캜 containing 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

Subsequently, the polarizer, each of the retardation films 1 to 12 produced in Examples 1 to 6 and Comparative Examples 1 to 6, and the protective film described later were placed on the back side in accordance with the following Steps 1 to 5, To-roll bonding to produce long circular polarizer plates.

Step 1: The retardation film was immersed in a 2 mol / L sodium hydroxide solution at 60 占 폚 for 90 seconds, followed by washing with water and drying, thereby saponifying the side to be bonded with the polarizer.

Step 2: The polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.

Step 3: In Step 2, excess adhesive adhered to the polarizer was lightly wiped off, and the polarizer was placed on the retardation film treated in Step 1. At that time, a tension of 50 N / m was applied to the retardation film and the polarizer so that relaxation did not occur.

Step 4: The laminated retardation film, polarizer and protective film in Step 3 were bonded at a pressure of 20 to 30 N / cm ² and a conveying speed of about 2 m / min.

Step 5: A sample obtained by bonding the polarizer, the retardation film and the protective film prepared in Step 4 in a drier at 80 占 폚 was dried for 2 minutes.

<Fabrication of Protective Film>

(Preparation of ester compound)

251 g of 1,2-propylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid and 0.191 g of tetraisopropyl titanate as an esterification catalyst were put into a 2 L four-necked flask equipped with a thermometer, And the temperature was gradually raised with stirring until the temperature reached 230 deg. C in a nitrogen stream. After dehydration condensation reaction for 15 hours, unreacted 1,2-propylene glycol was removed by distillation under reduced pressure at 200 占 폚 to obtain an ester compound. An acid value of 0.10 mgKOH / g, and a number average molecular weight of 450.

(Preparation of Dope)

Cellulose acetate (acetyl group substitution degree 2.88) 90 parts by mass

Ester compound 10 parts by mass

Tinuvin 928 (manufactured by BASF Japan Ltd.) 2.5 parts by mass

The particulate additive liquid 4 parts by mass

Methylene chloride 432 parts by mass

ethanol 38 parts by mass

And the mixture was completely dissolved while heating and stirring. The solution was filtered using Azumi-no. 24 of Azumi Co., Ltd. to prepare a dope solution.

(Film forming)

Subsequently, using a belt casting machine, the stainless steel band support was uniformly flexible. In the stainless steel band support, the solvent was evaporated until the amount of the residual solvent became 100%, and peeled off from the stainless band support. The web of the cellulose ester film was evaporated at 35 캜 to slit to 1.65 m in width and heated at 160 캜 while being stretched by 30% in the TD direction (film width direction) and a stretching magnification in the MD direction of 1 %. When the stretching was started, the amount of the residual solvent was 20%. Thereafter, the inside of the drying apparatus at 120 캜 was dried for 15 minutes while being conveyed by a plurality of rollers, slitted to a width of 1.49 m, knurled to 15 mm in width and 10 탆 in height at both ends of the film, To obtain a protective film. The amount of the residual solvent in the protective film was 0.2%, the film thickness was 40 탆, and the number of windings was 3900 m. The orientation angle of the protective film was measured using Axoscan manufactured by Axometorics, and as a result, it was within the range of 90 占 占 with respect to the film longitudinal direction.

&Lt; Fabrication of organic EL cell >

Using a 50-inch (127 cm) non-alkali glass having a thickness of 3 mm, an organic EL device having the configuration described in FIG. 8 of the same publication was prepared in accordance with the method described in the example of JP-A-2010-20925 Cells were fabricated.

&Lt; Fabrication of organic EL display &

Each of the circularly polarizing plates produced as described above was coated with an adhesive on the surface of the retardation film, and then bonded to the viewer side of the organic EL cell to produce each organic EL display.

&Lt; Evaluation of organic EL display >

Each of the organic EL displays manufactured as described above was evaluated as follows.

(Evaluation of visibility: black display)

A black image was displayed on the organic EL display under the condition that the illuminance at a position 5 cm higher than the outermost surface of the organic EL display was 1000 Lx in an environment of 23 캜 and 55% RH. Subsequently, with respect to the displayed black image, the visibility of the black image from the front position (0 deg. To the surface normal) of the organic EL display and the tilt angle of 40 deg. . &Lt; / RTI &gt; If the difference is?, There is no practical problem.

(Evaluation standard)

?: More than eight observers judged that the displayed image was black.

?: Six or more observers judged that the displayed image was black.

X: Five or less observers judged that the displayed image was black.

The evaluation results and the like are shown in Table 12 together with the production conditions of the retardation film.

As can be seen from Table 12, the additive represented by the formula (A) is contained, and the Spol is 0.03 or more and 0.15 or less, Sa is larger than 0.15, Ro (550) is 115 nm or more and 160 nm or less, ° or more and 85 ° or less (Examples 1 to 6), a retardation film having a sufficiently thin thickness, a high tear strength, and a low haze can be obtained as compared with the case where it is not otherwise (Comparative Examples 1 to 6). When an organic EL display is used by using the retardation film, a display image is obtained in a good condition.

[Industrial applicability]

According to the present invention, even in the case of a cellulose acylate film having a sufficiently thin thickness, the retardation of brittleness is sufficiently suppressed, and the retardation in the in-plane retardation is about 1/4 of the wavelength Film is provided. Further, when this retardation film is applied to an image display apparatus such as an organic EL display as a circularly polarizing plate, an image display apparatus capable of sufficiently suppressing reflection of external light and displaying a good image is provided.

Claims (6)

A long-shaped retardation film comprising a cellulose acylate resin and an additive,
Wherein the additive is an additive represented by the following formula (A)
The degree of orientation of the cellulose acylate resin calculated by the absorption spectroscopy is 0.03 or more and 0.15 or less,
The degree of orientation of the additive calculated by the absorption spectroscopy is greater than 0.15,
Plane retardation value of the retardation film at a wavelength of 550 nm is not less than 115 nm and not more than 160 nm,
Wherein an angle formed by the in-plane slow axis in the retardation film and the longitudinal direction of the retardation film is 15 ° or more and 85 ° or less.

(In the formula (A), Q represents an aromatic hydrocarbon ring, a non-aromatic hydrocarbon ring, an aromatic heterocyclic ring, or a non-aromatic heterocyclic ring, and each of Wa and Wb represents a hydrogen atom And the atom to which Wa binds and the atom to which Wb binds are adjacent to each other in the ring of Q and the Wa and Wb are different from each other and the Wa and Wb form a ring R ³ and R ³ are independently a substituent, R ³ is a substituent, m is 0 to 2, and when m is 2, two R ^{3 s} may be the same as or different from each other, The polymerization degree n is 1 to 10, and L ¹ and L ² each independently represent a single bond, an alkylene group, an alkenylene group, an alkynylene group, a -O- group, a - (C═O) ) -O- group, -NR _L - group, -S- group, - (O = S = O ) - group and _{- (C = O) -NR L} - 2 is selected from the group consisting of divalent linking groups, or It represents a combination of, L ¹ and R _L of the L ² represents a hydrogen atom or a substituent; The method according to claim 1,
Wherein the cellulose acylate resin has a total carbon number of an acyl group per glucose unit of 6.5 or less. 3. The method according to claim 1 or 2,
The in-plane retardation value Ro (450) of the retardation film at 450 nm, the in-plane retardation value Ro (550) at a wavelength of 550 nm and the in-plane retardation value Ro (650) ) And the following formula (2).
0.72? Ro (450) / Ro (550)? 0.94 (1)
0.83? Ro (550) / Ro (650)? 0.98 (2) 4. The method according to any one of claims 1 to 3,
Wherein the total degree of substitution of the acyl group per glucose unit of the cellulose acylate resin is not less than 1.5 and not more than 2.5. A circularly polarizing plate comprising the retardation film according to any one of claims 1 to 4. An image display apparatus comprising the retardation film according to any one of claims 1 to 4.

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