JPWO2013038684A1 - Organic EL display device - Google Patents

Abstract

The object of the present invention is to prevent the precipitation of the additive of the λ / 4 retardation film and to suppress the environmental fluctuation of the retardation value, the image is high-definition, the image quality is deteriorated, the hue is deteriorated with time and the light. An organic EL display device in which a decrease in extraction efficiency is suppressed is provided. The organic EL display device of the present invention includes a light emitting element and a circularly polarizing plate disposed on a surface on the viewing side of the light emitting element. The circularly polarizing plate includes a polarizer, the polarizer, and the light emitting element. A λ / 4 retardation film and a protective film which is disposed on the viewing side of the polarizer and has an ultraviolet absorption performance. The λ / 4 retardation film has an acetyl group substitution degree X Contains a cellulose ester satisfying the following formula (1), a compound (A) represented by the following formula, an ultraviolet absorber having an OH group, and a retardation value increasing agent, and the formula (1) 2.7 ≰X≰3.0 The λ / 4 retardation film satisfies the following formula (2), where Ro is the retardation value in the in-plane direction with respect to light having a wavelength of 550 nm, and Rth is the retardation value in the thickness direction. Formula (2) 100≰Ro≰170nm0≰Rth≰300nm

Description

  The present invention relates to an organic EL display device.

  A stretched film formed by stretching a resin film is used as an optical material of a component of a display device by utilizing its optical anisotropy. For example, in a liquid crystal display device, the stretched film can be used as a retardation film for optical compensation such as coloring prevention and viewing angle expansion, or the stretched film and a polarizer can be bonded together to be used as a polarizing plate. Are known.

  In recent years, the retardation film has been required for improving the display quality of the organic EL display device.

  In the organic EL display device, there is a problem that external light is reflected by the cell electrode and the image becomes whitish. In order to prevent this, a circular polarizing plate in which a retardation film having a retardation value of ¼ of the wavelength of visible light (hereinafter referred to as λ / 4 retardation film) and a polarizer are bonded is viewed. Attempts have been made to provide them.

  Incidentally, one of the techniques for improving the quality of an organic EL display device is to improve the image quality. However, since the luminous intensity of the organic EL blue light-emitting element is weak at present, the blue light-emitting element must be larger than other light-emitting elements such as red and green, and it is difficult to achieve high definition. was there. Further, since the ultraviolet light deterioration of the blue light emitting element is larger than that of the light emitting elements such as red and green, the hue balance is easily lost over time. Therefore, even if the protective film used in the conventional liquid crystal display device is diverted to the organic EL display device, there is a problem that the ultraviolet ray cutting performance is insufficient. The organic EL display device of the example of Patent Document 1 has a circularly polarizing plate on the viewing side; the circular polarizing plate is disposed on the viewing side, a protective film containing an ultraviolet absorber, and light emission. It has a λ / 4 retardation film which is arranged on the element side and does not contain an ultraviolet absorber.

  The circularly polarizing plates produced in the examples and comparative examples of Patent Document 1 have an absorptance of light having a wavelength of 300 to 380 nm immediately after production, which is about 100%. However, after a long period of use, the ultraviolet absorber contained in the protective film is also deteriorated, so that the ultraviolet absorbing performance of the protective film described in Patent Document 1 is still insufficient. Further, when light having a wavelength of 380 to 410 nm is absorbed as in Patent Document 1, the blue light extraction efficiency is lowered. Therefore, the blue light-emitting element must be enlarged, and it becomes difficult to increase the definition of the formed image.

  Patent Document 2 describes a circularly polarizing plate including a polarizer and a polycarbonate film as a λ / 4 retardation film. However, when the circularly polarizing plate described in Patent Document 2 is used in an organic EL display device, the refractive index of the polycarbonate film is as high as about 1.63, so that backscattering increases. Therefore, the light extraction efficiency of the organic EL display device is lowered, and the luminance of the display image is lowered. In order to increase the luminance, it is necessary to increase the power supply amount, and as a result, the advantage that the power consumption of the organic EL display device is small is lost.

  The λ / 4 retardation film is generally produced by stretching a film made of a plastic resin at a high magnification. However, since the degree of crystallinity of the plastic resin is increased by stretching at a high magnification, there has been a problem that resin additives and the like are deposited. This precipitation occurs remarkably particularly when an ultraviolet absorber is added to the film.

  Patent Document 3 proposes an additive highly compatible with a cellulose ester film. However, this document does not consider the problem of precipitation of additives that occurs remarkably in the presence of an ultraviolet absorber. Moreover, since the cellulose ester film has high moisture permeability, the dimension after stretching tends to change greatly. Since the change in the dimension of the cellulose ester film causes a change in the retardation value, the cellulose ester film stretched at a high magnification also has a problem that the retardation value easily changes depending on the humidity of the environment. The fluctuation of the retardation value of the film leads to a decrease in the external light antireflection function of the organic EL display device.

  In the end, no way to solve these problems has been found.

JP 2005-189645 A JP 2007-171756 A JP 2010-163482 A

  The present invention prevents the precipitation of the additive of the λ / 4 retardation film and suppresses the environmental fluctuation of the retardation value, increases the definition of the image of the organic EL display device, suppresses the deterioration of the image quality, and changes the hue due to ultraviolet rays. It was made to solve the above-mentioned problems of suppressing deterioration and suppressing light extraction efficiency.

  That is, the object of the present invention is to prevent the precipitation of the additive of the λ / 4 retardation film and to suppress the environmental fluctuation of the retardation value, the image is high-definition, the image quality is deteriorated, and the hue is deteriorated due to ultraviolet rays over time. An organic EL display device in which a decrease in light extraction efficiency is suppressed.

  Among the above problems, in order to suppress the deterioration of the hue due to ultraviolet rays over time, an ultraviolet absorber is added to a cellulose ester resin having excellent bonding suitability by PVA to the polarizer, and when it is stretched at a high magnification, the precipitation of the additive The film was cloudy. It is thought that the additive which precipitates contains the conventional wavelength dispersion regulator, a ultraviolet absorber, etc. This white turbidity becomes more remarkable when a matting agent (fine particles) is contained in the film. However, the fine particles are an additive necessary for ensuring the slipperiness of the film. When a clouded film is used for an organic EL display device, there is a problem that a displayed image is entirely white. Therefore, in order to prevent this precipitation, various combinations of additives were examined. As a result, it has been found that precipitation of these additives does not occur by employing a compound (A) described later and an ultraviolet absorber having an OH group. As a result, it has been found that even when a matting agent (fine particles) is included, a retardation film can be obtained in which the film does not become cloudy and can also suppress environmental fluctuations in the retardation value.

（Ｒ１、Ｒ２、Ｒ３、Ｒ４およびＲ５は、それぞれ独立に置換基を表し；ｎは、０〜２の整数を表し；Ｌ１、Ｌ２は、それぞれ独立に単結合または２価の連結基を表す）前記λ／４位相差フィルムは、波長５５０ｎｍの光に対する面内方向の位相差値をＲｏ、厚み方向の位相差値をＲｔｈとしたとき、下記式（２）を満たす、有機ＥＬ表示装置。
式（２） １００≦Ｒｏ≦１７０ｎｍ
０≦Ｒｔｈ≦３００ｎｍ
［２］ 前記化合物（Ａ）が、１００℃〜３００℃の温度範囲のいずれかで液晶相である、［１］に記載の有機ＥＬ表示装置。
［３］ 前記化合物（Ａ）の含有量は、前記セルロースエステルに対して０．１〜３０質量％である、［１］または［２］に記載の有機ＥＬ表示装置。
［４］ 前記λ／４位相差フィルムのヘーズが、０．５％以下である、［１］〜［３］のいずれかに記載の有機ＥＬ表示装置。
［５］ 前記偏光子の視認側の面が前記保護フィルムと接しており、かつ前記偏光子の前記発光素子側の面が前記λ／４位相差フィルムと接している、［１］または［２］に記載の有機ＥＬ表示装置。That is, it has been found that the solution of the problem in the present invention can be achieved by adopting the following configuration.
[1] An organic EL display device including a light emitting element and a circularly polarizing plate disposed on a viewing side surface of the light emitting element, wherein the circularly polarizing plate includes a polarizer, the polarizer, and the light emitting element. A λ / 4 retardation film disposed between and a viewing side of the polarizer, and a protective film having ultraviolet absorption performance, wherein the λ / 4 retardation film is substituted with an acetyl group A cellulose ester satisfying the following formula (1) with a degree X, a compound (A) represented by the following formula, an ultraviolet absorber having an OH group, and a retardation value increasing agent;
Formula (1) 2.7 <= X <= 3.0

(R1, R2, R3, R4 and R5 each independently represent a substituent; n represents an integer of 0 to 2; L1 and L2 each independently represent a single bond or a divalent linking group) The λ / 4 retardation film is an organic EL display device that satisfies the following formula (2), where Ro is a retardation value in an in-plane direction with respect to light having a wavelength of 550 nm, and Rth is a retardation value in a thickness direction.
Formula (2) 100 ≦ Ro ≦ 170 nm
0 ≦ Rth ≦ 300nm
[2] The organic EL display device according to [1], wherein the compound (A) is in a liquid crystal phase in any temperature range of 100 ° C to 300 ° C.
[3] The organic EL display device according to [1] or [2], wherein the content of the compound (A) is 0.1 to 30% by mass with respect to the cellulose ester.
[4] The organic EL display device according to any one of [1] to [3], wherein the haze of the λ / 4 retardation film is 0.5% or less.
[5] The surface on the viewing side of the polarizer is in contact with the protective film, and the surface on the light emitting element side of the polarizer is in contact with the λ / 4 retardation film, [1] or [2 ] The organic electroluminescence display device of description.

  By adopting the configuration of the present invention, it is possible to provide a method for efficiently solving the problems such as suppression of environmental fluctuations of retardation values, suppression of deterioration of image extraction due to high-definition of images and suppression of deterioration of light extraction efficiency due to ultraviolet rays. An organic EL display device to which the same is applied can be provided.

It is an example of a structure of the organic electroluminescent display apparatus of this invention. It is a schematic diagram which shows the diagonal stretch by a tenter. It is a schematic diagram which shows the track | orbit of the rail of the tenter used for extending diagonally.

  The present invention prevents the precipitation of additives in the λ / 4 retardation film and suppresses environmental fluctuations of the retardation value, increases the definition of the organic EL display device, suppresses the deterioration of image quality, and suppresses the temporal deterioration of hue due to ultraviolet rays. The present invention was made to solve the above-mentioned problem of suppressing the decrease in light extraction efficiency.

  The environmental fluctuation of the retardation value of the λ / 4 retardation film requires that the fluctuation rate of the in-plane retardation value Ro be 20% or less at 23 ° C. and 20 to 80% RH. Is achieved.

  According to the present invention, it is possible to provide a method for efficiently solving problems such as prevention of whitening of an image, suppression of deterioration of an external light reflection preventing function, high definition, suppression of temporal deterioration of hue due to ultraviolet rays, and suppression of reduction of light extraction efficiency. An organic EL display device to which the same is applied can be provided.

  The conventional organic EL display device has a problem that the hue changes with time because the light resistance of the light emitting element is low. In addition, a λ / 4 retardation film made of a cellulose ester film generally has a problem that the retardation value tends to fluctuate greatly depending on the environment. However, the technique which solves said problem was calculated | required from the point that the cellulose-ester film is very excellent in polarizing plate processability.

  At present, the problem of the temporal change in hue due to ultraviolet light is addressed by arranging a conventional polarizer protective film having ultraviolet absorption performance on the viewing side of the organic EL display device (protective film 11 in FIG. 1 described later). But not enough. Before reaching the present invention, we first add an ultraviolet absorber to the λ / 4 retardation film (λ / 4 retardation film 9 in FIG. 1 described later) necessary for the light emitting element side of the organic EL display device. Tried. As a result, it was found that the λ / 4 retardation film was clouded by the precipitation of the λ / 4 retardation film due to the high magnification stretching. The additive to be deposited includes a conventional wavelength dispersion adjusting agent, an ultraviolet absorber and the like. This white turbidity becomes more prominent when a matting agent (fine particles) is contained in the λ / 4 retardation film. However, the fine particles are an additive necessary for ensuring the slipperiness of the λ / 4 retardation film. As a result of studying various combinations of additives, the present invention has been achieved.

  That is, suppression of precipitation of the additive during stretching is performed by 1) selecting “compound (A)” to be described later as a wavelength dispersion adjusting agent, thereby increasing compatibility with the cellulose ester, and 2) as an ultraviolet absorber. By selecting the “ultraviolet absorber having an OH group”, it can be realized by interacting with the compound (A), and 3) by containing a retardation value increasing agent to lower the draw ratio. Reduction of the environmental fluctuation of the retardation value of the λ / 4 retardation film can be realized by 1) suppressing the precipitation of additives and 2) reducing the draw ratio.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

[Organic electroluminescence display device]
FIG. 1 shows an example of the configuration of the organic EL display device of the present invention, but the present invention is not limited to this. As shown in FIG. 1, the organic EL display device A includes an organic EL element B (light emitting element) and a circularly polarizing plate C disposed on the surface on the viewing side.

  The organic EL element B has a metal electrode 2, a TFT 3, an organic light emitting layer 4, a transparent electrode (ITO etc.) 5, an insulating layer 6, a sealing layer 7, and a film 8 (omitted) on a substrate 1 made of glass or polyimide. Yes).

  As described above, in general, in an organic EL display device, 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. Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, it may be a laminate of such a light-emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light-emitting layer, and electron injection layer.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

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

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device including an organic EL element having a transparent electrode on the surface side of an organic light emitting layer that emits light when a voltage is applied and a metal electrode on the back surface side of the organic light emitting layer, the surface side of the transparent electrode (visible) A polarizer can be provided on the side), and a retardation film can be provided between the transparent electrode and the polarizer.

  The retardation film and the polarizer have a function of polarizing light incident from the outside and reflected by the metal electrode. Therefore, there is an effect that the mirror surface of the metal electrode is not visually recognized from the outside by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation film with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizer and the retardation film to π / 4. .

  That is, the external light incident on the organic EL display device is transmitted only by the linearly polarized light component by the polarizer, and this linearly polarized light is generally elliptically polarized light by the retardation film. In particular, the retardation film has a λ / 4 retardation. When the angle between the polarization direction of the polarizer and the retardation film is π / 4, the film is circularly polarized.

  That is, the circularly polarizing plate C includes a polarizer 10, a λ / 4 phase difference film 9 disposed on the organic EL element B side of the polarizer 10, and a protective film 11 disposed on the viewing side of the polarizer. . The λ / 4 retardation film and the protective film 11 may be disposed in contact with the polarizer; they may be disposed through other layers, but are preferably disposed in contact with the polarizer. .

  As will be described later, the protective film 11 preferably has ultraviolet absorbing performance in order to suppress deterioration due to ultraviolet rays of the organic light emitting layer constituting the organic EL element B. The protective film 11 is preferably laminated with a cured layer 12. The hardened layer 12 not only prevents the surface of the organic EL display device from being scratched but also has an effect of preventing warpage due to the circularly polarizing plate. Further, an antireflection layer 13 may be provided on the cured layer 12. The thickness of the organic EL element itself is about 1 μm.

  As described above, the external light incident on the organic EL display device of the present invention is transmitted only by the linearly polarized light component by the polarizer of the circularly polarizing plate C, and this linearly polarized light becomes circularly polarized light by the λ / 4 retardation film. This circularly polarized light passes through the transparent substrate, the transparent electrode, and the organic thin film, and is reflected by the metal electrode. The reflected light again passes through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again by the λ / 4 retardation film. And since this linearly polarized light is orthogonal to the polarization direction (transmission axis) of a polarizer, it cannot permeate | transmit a polarizer. As a result, the mirror surface of the metal electrode can be completely shielded.

[Circularly polarizing plate]
As described above, the circularly polarizing plate is disposed on the polarizer, the λ / 4 retardation film disposed on the organic EL element side of the polarizer, and the opposite side (viewing side) of the polarizer on the organic EL element side. Protective film.

[Λ / 4 retardation film]
The “λ / 4 retardation film” in the present invention means a film having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The λ / 4 retardation film has an in-plane retardation value Ro of about ¼ for a predetermined wavelength of light (usually in the visible light region).

  The λ / 4 retardation film used in the present invention is a cellulose ester satisfying the formula (1) described later with an acetyl group substitution degree X, a compound (A), an ultraviolet absorber having an OH group, and a retardation value. As well as other ingredients as needed.

(Cellulose ester)
The λ / 4 retardation film used in the present invention contains a cellulose ester. The cellulose ester is a compound obtained by esterifying cellulose with an aliphatic carboxylic acid or aromatic carboxylic acid having 2 to 7 carbon atoms, and is preferably cellulose acetate.

That is, the λ / 4 retardation film used in the present invention contains cellulose acetate that satisfies the condition defined by the following formula (1).
Formula (1) 2.7 <= X <= 3.0
In the above formula (1), X represents the degree of acetyl substitution.

  The cellulose acetate used in the present invention is characterized in that the average degree of acetyl group substitution is 2.7 or more, preferably in the range of 3.0. The average degree of acetyl group average substitution here means the average number of esterified (acetylated) hydroxyl groups (hydroxyl groups) among the three hydroxyl groups (hydroxyl groups) of each anhydroglucose constituting cellulose. Value, indicating a value in the range of 0-3.0.

  In the present invention, the portion not substituted with an acetyl group is usually present as a hydroxyl group (hydroxyl group), and these can be synthesized by a known method.

  In addition, the substitution degree of an acetyl group is calculated | required by the method prescribed | regulated to ASTM-D817-96 (test methods, such as a cellulose acetate).

  The number average molecular weight (Mn) of the cellulose acetate used in the present invention is preferably in the range of 30,000 to 300,000 because the mechanical strength of the resulting film is strong. Furthermore, the thing of 50,000-200,000 is used preferably.

  The value of the ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose acetate is preferably 1.4 to 3.0.

The weight average molecular weight Mw and number average molecular weight Mn of cellulose acetate were measured using gel permeation chromatography (GPC). The measurement conditions are as follows.
Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  Although there is no limitation in particular as a cellulose which is a raw material of the cellulose acetate used for this invention, Cotton linter, wood pulp, kenaf etc. can be mentioned. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

  The cellulose acetate used in the present invention can be produced by a known method. In general, cellulose is mixed with raw material cellulose, a predetermined organic acid (such as acetic acid), acid anhydride (such as acetic anhydride), and a catalyst (such as sulfuric acid) to esterify (acetylate) cellulose, The reaction proceeds until the ester (acetylation) is formed. In the triester (acetylation), the three hydroxyl groups (hydroxyl groups) of the glucose unit are substituted with acetyl groups of organic acids. Next, cellulose acetate having a desired degree of acetyl group substitution is synthesized by hydrolyzing the cellulose triester. Thereafter, cellulose acetate can be obtained through steps such as filtration, precipitation, washing with water, dehydration, and drying.

  Specifically, for example, it can be synthesized with reference to the method described in JP-A-10-45804.

(Compound (A))
The λ / 4 retardation film used in the present invention is characterized by containing a compound (A) represented by the following formula together with cellulose triacetate satisfying the formula (1).

  In the compound (A) represented by the following formula, the molecular absorption wavelength derived from the transition electric dipole moment My substantially perpendicular to the molecular long axis direction has a transition electric dipole moment substantially parallel to the molecular long axis direction. The magnitude of transition electric dipole moment | My | which is longer than the molecular absorption wavelength derived from Mx and is substantially perpendicular to the molecular long axis direction is substantially equal to the transition electric dipole moment in the direction substantially parallel to the molecular long axis direction. It is a compound showing a value larger than the size | Mx |.

  The compound (A) having the above properties can be added mainly for adjusting the wavelength dispersion of the film.

Hereinafter, the compound (A) represented by the following formula used in the present invention will be described in detail.

  In the above formula, R1, R2, R3, R4 and R5 each independently represent a substituent.

  Preferred examples of the substituent represented by R1 and R2 include a halogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, and a heterogeneous group having 3 to 30 carbon atoms. A cyclic group, a hydroxyl group, a carboxyl group, an alkoxy group having 1 to 30 carbon atoms, an aryloxy group having 6 to 30 carbon atoms, an acyloxy group, a cyano group, an amino group, etc. are included, preferably an alkyl having 1 to 8 carbon atoms. It is a group.

  Preferred examples of the substituent represented by R3 and R4 include a trifluoromethyl group, a cyano group, a nitro group, a carbonyl group, a carbamoyl group, etc., preferably a cyano group, an alkylcarbonyl group having 2 to 30 carbon atoms, a carbon These are an arylcarbonyl group having 6 to 30 carbon atoms, an alkyloxycarbonyl group having 2 to 30 carbon atoms, an aryloxycarbonyl group having 6 to 30 carbon atoms, and a carbamoyl group. R3 and R4 may be bonded to each other to form a ring.

In the above formula, L1 and L2 each independently represent a single bond or a divalent linking group. Examples of the divalent linking group in L1 and L2 include the following examples.

  Among these, -O-, -COO-, and -OCO- are particularly preferable.

  Examples of the substituent represented by R5 include those similar to the substituents represented by R1 and R2, and preferably a halogen atom, an alkyl group having 1 to 8 carbon atoms, a cyano group, an alkoxy group having 1 to 8 carbon atoms, or the like. . n is an integer of 0-2.

Specific examples of the compound (A) include the following compounds.

  The compound (A) has good compatibility with the cellulose ester. Especially compound A-2 and A-4 have high compatibility with a cellulose ester compared with the conventional wavelength dispersing agent. Therefore, it is thought that precipitation of the additive containing the compound (A) can be suppressed when the film is stretched.

  As for these synthesis methods, a known method, for example, a method described in JP-A No. 2010-163482 can be used.

  The compound (A) is preferably in a liquid crystal phase in any temperature range of 100 ° C to 300 ° C. Whether or not the compound (A) exhibits a liquid crystal phase can be confirmed by observing the state of the compound (A) in the above temperature range with a polarizing microscope.

  The content of the compound (A) is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and preferably 1 to 10% by mass with respect to the cellulose ester. Further preferred. When the content of the compound (A) is too large, precipitation tends to occur when a film containing the compound (A) is stretched, and when the content of the compound (A) is too small, the wavelength dispersion may not be sufficiently adjusted.

(Phase difference improver)
A retardation value improver is a compound that improves the retardation value of a film and has an effect of suppressing environmental fluctuation of the retardation value.

  As long as the effect of the present invention is not impaired, the retardation value improver may be a known rod-like compound or discotic compound.

The rod-shaped compound preferably has at least one aromatic ring and has a linear molecular structure. Examples of the rod-like compound include the rod-like compound represented by the general formula (2) described in JP 2010-98026 A, in addition to the compound B-1 having the following structure.

  In formula (2), Ar1 and Ar2 each independently represent an aryl group or an aromatic heterocyclic group. Examples of the aromatic heterocyclic ring constituting the aromatic heterocyclic group include a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, and a furazane ring. , Triazole ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, and 1,3,5-triazine ring. Examples of the aromatic ring constituting the aryl group include benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring and pyrazine ring. Is a benzene ring.

  The aryl group or aromatic heterocyclic group includes a halogen atom, cyano, carboxyl, hydroxyl, amino, alkyl-substituted amino group, acyl group, acyloxy group, amide group, alkoxycarbonyl group, alkoxy group, alkylthio group, and alkyl group. It may further have a substituent.

  In the formula (2), L1 is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, a divalent saturated heterocyclic group, —O—, —CO—, and combinations thereof. .

  The alkylene group may have a cyclic structure. The alkylene group having a cyclic structure is preferably cyclohexylene, more preferably 1,4-cyclohexylene. Carbon number of an alkylene group becomes like this. Preferably it is 1-10, More preferably, it is 1-8.

  Carbon number of alkenylene group and alkynylene group becomes like this. Preferably it is 2-10, More preferably, it is 2-8, More preferably, it is 2-6, Especially preferably, it is 2. Examples of saturated heterocyclic rings constituting divalent saturated heterocyclic groups include piperazine-1,4-diylene, 1,3-dioxane-2,5-diylene and 1,3,2-dioxaborolane-2,5- Diylene etc. are included.

The example of the bivalent coupling group which consists of a combination is shown.
L-1: —O—CO-alkylene group —CO—O—
L-2: -CO-O-alkylene group -O-CO-
L-3: —O—CO—alkenylene group —CO—O—
L-4: -CO-O-alkenylene group -O-CO-
L-5: -O-CO-alkynylene group -CO-O-
L-6: -CO-O-alkynylene group -O-CO-
L-7: -O-CO-divalent saturated heterocyclic group -CO-O-
L-8: -CO-O-divalent saturated heterocyclic group -O-CO-

The discotic compound is preferably a compound having a 1,3,5-triazine ring. The compound having a 1,3,5-triazine ring is preferably a compound represented by the following general formula (3).

In the general formula (3), X ¹ is a single bond, —NR ⁴ —, —O— or —S—; X ² is a single bond, —NR ⁵ —, —O— or —S—. X ³ is a single bond, —NR ⁶ —, —O— or —S—. X ¹ , X ² and X ³ are preferably —NR ⁴ —, —NR ⁵ — and —NR ⁶ —, respectively.

R ¹ , R ² and R ³ are an alkyl group, an alkenyl group, an aryl group or a heterocyclic group; preferably an aryl group. R ⁴ , R ⁵ and R ⁶ are a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group, preferably a hydrogen atom.

The number of carbon atoms of the alkyl group represented by R ¹ to R ³ is preferably 1 to 10, more preferably 1-8, more preferably 1-6. The alkyl group may have a substituent. The number of carbon atoms of the alkenyl group represented by R ¹ to R ³ is preferably 2-10, more preferably 2-8, further preferably 2-6. The alkyl group and alkenyl group may have a substituent.

The aryl group represented by R ^{1 to} R ³ is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. The aryl group may have a substituent.

  Specific examples of the substituent that the alkyl group, alkenyl group, and aryl group may have include an alkyl group, a halogen atom, an alkoxy group, and an acyloxy group.

^{-X 1 -R 1, -X 2 -R} 2 and ^-X 3 -R ³ are preferably the same substituents.

Specific examples include compounds having the following structure.

  The cellulose ester film having an acetyl group substitution degree X satisfying the above formula (1) used in the present invention hardly increases the in-plane retardation values Ro and Rth even if it is stretched alone. Therefore, even if the draw ratio is increased so as to express the phase difference value as expressed by the above formula (2), it breaks before reaching the phase value of the formula (2). The purpose of adding a retardation value increasing agent such as compound B-1 or B-2 is to increase the retardation value expression.

  The content of the retardation value increasing agent is preferably 0.2 to 30% by mass and more preferably 1 to 20% by mass with respect to the cellulose ester. If the content of the retardation value increasing agent is too large, precipitation is likely to occur when a film containing the retardation value is stretched. If the content of the retardation value increasing agent is too small, the retardation value cannot be sufficiently increased. Sometimes.

(UV absorber)
The λ / 4 retardation film used in the present invention and the protective film described later preferably contain an ultraviolet absorber. Among these, the λ / 4 retardation film used in the present invention preferably contains an ultraviolet absorber having an OH group. The ultraviolet absorber having an OH group easily interacts with the compound (A); the compound (A) is considered to have high compatibility with the cellulose ester as described above. Thus, it is considered that the compound (A) works like a compatibilizing agent that eliminates incompatibility between the UV absorber having an OH group and the cellulose ester. For this reason, it is considered that when the film is stretched, it is difficult for the ultraviolet absorber to precipitate.

  Examples of the ultraviolet absorber having an OH group include benzotriazole-based, 2-hydroxybenzophenone-based, and salicylic acid phenyl ester-based compounds. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone And benzophenones.

  Of these UV absorbers, UV absorbers with a molecular weight of 400 or higher are less likely to volatilize at high boiling points and are difficult to disperse even during high temperature molding, so the weather resistance is effectively improved with a relatively small amount of addition. can do.

  Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- (1, 1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ( Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid Bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl L] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine and the like, hindered phenol and hindered amine A hybrid system having both structures can be mentioned, and these can be used alone or in combination of two or more. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

Commercially available products may be used. For example, TINUVIN such as TINUVIN 109, TINUVIN 171, TINUVIN 234, TINUVIN 326, TINUVIN 327, TINUVIN 328, and TINUVIN 928 manufactured by BASF Japan Ltd. can be preferably used.

  The content of the ultraviolet absorber is preferably 0.5 to 4% by mass and more preferably 0.6 to 3.5% by mass with respect to the λ / 4 retardation film. When the content of the ultraviolet absorber is too large, precipitation is likely to occur when a film containing the ultraviolet absorber is stretched, and when the content of the ultraviolet absorber is too small, the ultraviolet degradation may not be sufficiently suppressed.

  The λ / 4 retardation film used in the present invention can be used in combination with a thermoplastic resin other than the cellulose acetate as long as the effects of the present invention are not impaired.

  Here, the “thermoplastic resin” refers to a resin that becomes soft when heated to the glass transition temperature or melting point and can be molded into a desired shape.

  General thermoplastic resins include polyethylene (PE), high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS). Polyvinyl acetate (PVAc), Teflon (registered trademark) (polytetrafluoroethylene, PTFE), ABS resin (acrylonitrile butadiene styrene resin), AS resin, acrylic resin (PMMA), and the like can be used.

  In addition, it is possible to perform the kind of resin and the combination of molecular weight according to the use of this invention.

  The λ / 4 retardation film of the present invention may be obtained by appropriately mixing polymer components other than cellulose resin. The polymer component to be mixed is preferably one having excellent compatibility with the cellulose resin, and the transmittance when formed into a film is 80% or more, more preferably 90% or more, and further preferably 92% or more.

  Furthermore, various antioxidants can also be added to the λ / 4 retardation film in order to improve the thermal decomposability and thermal colorability during molding. In addition, an antistatic agent can be added to impart antistatic performance to the λ / 4 retardation film. Further, the λ / 4 retardation film may further contain a plasticizer, a deterioration preventing agent, a peeling aid, a surfactant, a dye, fine particles and the like.

(Plasticizer)
The λ / 4 retardation film used in the present invention preferably contains a plasticizer. In particular, the λ / 4 retardation film used in the present invention preferably contains a polyester plasticizer having a number average molecular weight (Mn) of 1000 or more and 10,000 or less.

  There is no restriction | limiting in particular about the specific structure of a polyester plasticizer, The polyester plasticizer which has an aromatic ring or a cycloalkyl ring in a molecule | numerator can be used. As a polyester plasticizer, the polyester plasticizer represented by the following general formula (a) is mentioned, for example.

Formula (a)
B- (GA) n-GB
In the general formula (a), B represents a benzene monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G represents an alkylene glycol residue having 2 to 12 carbon atoms, and an aryl glycol residue having 6 to 12 carbon atoms. Or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more. Represent.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the polyester plasticizer include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. Or as a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the polyester plasticizer include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and the like. Can be used singly or as a mixture of two or more. Furthermore, examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and the like.

  The polyester plasticizer preferably contained in the λ / 4 retardation film used in the present invention has a number average molecular weight of 1,000 to 10,000. More preferably, it is 6000-8000.

  The acid value of the polyester plasticizer is preferably 0.5 mgKOH / g or less, more preferably 0.3 mgKOH / g or less. Further, the hydroxyl value of the polyester plasticizer is preferably 25 mgKOH / g or less, more preferably 15 mgKOH / g or less. In addition, an acid value means the milligram number of potassium hydroxide required in order to neutralize the acid (carboxyl group which exists in a sample) contained in 1g of samples. The acid value is measured according to JIS K0070.

  In addition to the polyester plasticizer described above, various plasticizers may be added to the λ / 4 retardation film used in the present invention. Examples of such plasticizers include polyhydric alcohol ester plasticizers, glycolate plasticizers, phthalate ester plasticizers, citrate ester plasticizers, fatty acid ester plasticizers, and phosphate ester plasticizers. , Polycarboxylic acid ester plasticizers, acrylic plasticizers, and the like.

  The λ / 4 retardation film used in the present invention includes an ester compound in which 1 to 12 or less of at least one pyranose structure or furanose structure is included and all or part of the OH groups of the structure are esterified. It is preferable. In the present invention, these ester compounds are collectively referred to as “sugar ester compounds”.

  Examples of sugar ester compounds include the following, but the present invention is not limited to these.

  First, as a compound (sugar) having a pyranose structure or a furanose structure, glucose, galactose, mannose, fructose, xylose, or arabinose, lactose, sucrose, nystose, 1F-fructosylnystose, stachyose, maltitol, lactitol, lactulose , Cellobiose, maltose, cellotriose, maltotriose, raffinose, and kestose.

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable. Examples thereof include sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, and more preferably sucrose.

  The monocarboxylic acid used for esterifying all or part of the OH group of the above-mentioned compound (sugar) having a pyranose structure or furanose structure for the purpose of constituting a sugar ester compound is not particularly limited and is publicly known. Aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. The carboxylic acid used may be one kind alone or a mixture of two or more kinds.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid; Examples thereof include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferred alicyclic monocarboxylic acids include acetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, and naphthalene. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralincarboxylic acid, or derivatives thereof. More specifically, xylyl acid, hemelic acid, mesitylene acid, prenicylic acid, γ-isodryl. Acid, duryl acid, mesitoic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropaic acid, hydrocinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid, creosote Acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyrocatechuic acid, β Resorcylic acid, vanillic acid, isovanillic acid, veratromic acid, o-veratrumic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratormic acid, o-homoveratrumic acid, phthalonic acid, p-coumaric acid However, benzoic acid is particularly preferable.

  From the viewpoint of stabilizing the display quality by suppressing the fluctuation of the retardation value in the λ / 4 retardation film used in the present invention, the sugar ester compound described above is based on 100 parts by mass of the λ / 4 retardation film. 1 to 30 parts by mass, and more preferably 5 to 30 parts by mass. Within this range, it is preferable that the excellent effects of the present invention are exhibited and there is no bleeding out.

(Phosphorus flame retardant)
For the λ / 4 retardation film used in the present invention, a flame retardant acrylic resin composition containing a phosphorus flame retardant may be used. Phosphorus flame retardants used here include red phosphorus, triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, aryl phosphonate compound, aryl phosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphorus. Examples thereof include one or a mixture of two or more selected from acid esters, halogen-containing condensed phosphates, halogen-containing condensed phosphonates, halogen-containing phosphites, and the like.

  Specific examples include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl). Examples thereof include phosphate and tris (tribromoneopentyl) phosphate.

(Matting agent)
In addition, the λ / 4 retardation film used in the present invention has, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydration in order to improve handleability. It is preferable to include a matting agent such as inorganic fine particles such as calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate, and a crosslinked polymer. Among these, silicon dioxide is preferably used because it can reduce the haze of the film.

  The primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm.

  The content of the fine particles is preferably 0.05 to 1.0% by mass and more preferably 0.1 to 0.8% by mass with respect to the cellulose ester. When there is too much content of microparticles | fine-particles, there exists a possibility of raising the haze of a film. On the other hand, if the content of fine particles is too small, there may be cases where sufficient slipperiness cannot be imparted to the film.

The λ / 4 retardation film used in the present invention may contain calcium and magnesium. In that case, it is preferable that the total amount of calcium and magnesium and the amount of acetic acid satisfy the following relational expression (a). .
Relational expression (a)
1.0 ≦ (acetic acid amount) / (total amount of calcium and magnesium) ≦ 30

  Calcium and magnesium are contained in the cellulose ester used as a raw material for the λ / 4 retardation film. However, in order to neutralize and stabilize the acid catalyst (especially sulfuric acid) added to the cellulose ester production process, It may be added as a hydroxide or metal salt (inorganic acid salt, organic acid salt). Moreover, you may add as a metal oxide, a metal hydroxide, and a metal salt (inorganic acid salt, organic acid salt) at the time of optical film forming.

  Cellulose acetate uses acetic anhydride or acetic acid as a reaction solvent or esterifying agent in the production process. Unreacted acetic anhydride is hydrolyzed by a reaction stopper (water, alcohol, acetic acid, etc.) to produce acetic acid. The amount of acetic acid contained in the λ / 4 retardation film refers to the total amount of residual acetic acid and free acetic acid.

  In the above relational expression (a), when the amount of acetic acid / (total amount of calcium and magnesium) is less than 1.0, light scattering due to calcium and magnesium metal salts occurs, which is not preferable. On the other hand, if it exceeds 30, the deterioration of the polarizer is accelerated by acetic acid after the λ / 4 retardation film is bonded to the polarizer, which is not preferable.

  The total amount of calcium and magnesium contained in the λ / 4 retardation film is preferably 5 to 130 ppm, more preferably 5 to 80 ppm, and still more preferably 5 to 50 ppm.

  The calcium and magnesium contained in the λ / 4 retardation film can be quantified by a known method. For example, after the dried cellulose ester is completely burned, the ash is dissolved in hydrochloric acid and pretreated. It can be measured by the atomic absorption method after the measurement. The measured value is obtained in units of ppm as the calcium and magnesium contents in 1 g of the completely dry cellulose ester.

  The amount of acetic acid contained in the λ / 4 retardation film is preferably 20 to 500 ppm, more preferably 25 to 250 ppm, and still more preferably 30 to 150 ppm.

  A known method can be used to determine the amount of acetic acid contained in the λ / 4 retardation film. For example, the following method can be used. The λ / 4 retardation film is dissolved in methylene chloride, and methanol is added to perform reprecipitation. The amount of acetic acid can be obtained by filtering the supernatant and measuring the supernatant with gas chromatography.

  The melting point of the λ / 4 retardation film used in the present invention is preferably in the range of 200 to 290 ° C. Methods for adjusting the melting point within the above range include controlling the degree of substitution of cellulose acetate or adding a plasticizer.

Properties of λ / 4 retardation film (retardation value and wavelength dispersion characteristic)
The λ / 4 retardation film used in the present invention has an in-plane retardation value Ro (550) measured at a wavelength of 550 nm, preferably in the range of 100 to 170 nm, more preferably 120 to 160 nm. More preferably, it is 130-150 nm.

  The λ / 4 retardation film having Ro in the above preferred range can convert linearly polarized light entering from the direction perpendicular to the film surface into circularly polarized light and circularly polarized light into linearly polarized light.

  Rth represents a retardation value in the thickness direction. Rth measured at a wavelength of 550 nm is preferably in the range of 0 to 300 nm, more preferably 0 to 140 nm, still more preferably 10 to 100 nm, and particularly preferably 20 to 80 nm.

  The λ / 4 retardation film used in the present invention is a retardation plate having a retardation of approximately ¼ of the wavelength in the visible light wavelength range in order to obtain almost perfect circularly polarized light in the visible light wavelength range. (Film) is preferred.

“Retardation of approximately ¼ in the wavelength range of visible light” means that the longer the wavelength is from 400 to 700 nm, the larger the retardation is,
1) In a λ / 4 retardation film, an in-plane represented by the following formula (i) measured at a wavelength of 450 nm with respect to an in-plane retardation value Ro (550) represented by the following formula (i) measured at a wavelength of 550 nm The ratio of the retardation value Ro (450) (Ro (450) / Ro (550)) is preferably 0.72 or more and 0.92 or less,
2) In λ / 4 retardation film, in-plane represented by the following formula (i) measured at a wavelength of 550 nm with respect to the in-plane retardation value Ro (650) represented by the following formula (i) measured at a wavelength of 650 nm The ratio of the retardation value Ro (550) (Ro (550) / Ro (650)) is preferably 0.84 or more and 0.97 or less.

The in-plane retardation value Ro and the retardation value Rth in the thickness direction are defined by the following formula (i).
Formula (i) Ro = (nx−ny) × d
Rth = {(nx + ny) / 2−nz} × d

  In the above formula (i), nx, ny, and nz are refractive indexes at 23 ° C. and 55% RH, respectively, and nx is the maximum refractive index in the plane of the film (refractive index in the slow axis direction), ny is the refractive index in the direction perpendicular to the slow axis in the film plane, nz is the refractive index in the thickness direction of the film, and d is the thickness (nm) of the film.

  Ro can be measured using an automatic birefringence meter. Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), Ro is calculated by birefringence measurement at each wavelength in an environment of 23 ° C. and 55% RH.

  A circularly polarizing plate is obtained by laminating so that the angle between the slow axis of the λ / 4 retardation film and the transmission axis of the polarizer described later is substantially 45 °. “Substantially 45 °” means 40 to 50 °. The angle between the slow axis in the plane of the λ / 4 retardation film and the transmission axis of the polarizer is preferably 41 to 49 °, more preferably 42 to 48 °, and 43 to 47 °. More preferably, it is most preferably 44 to 46 °.

(Haze)
The haze of the λ / 4 retardation film is preferably less than 0.8%, more preferably 0.5% or less. The haze of the film can be measured using a haze meter (NDH1001-DP, manufactured by Nippon Denshoku Industries Co., Ltd.).

(size)
The film thickness of the λ / 4 retardation film used in the present invention is not particularly limited, but 10 to 250 μm is used. In particular, the film thickness is particularly preferably 10 to 100 μm. More preferably, it is 30-60 micrometers.

(Surface roughness)
In addition, the arithmetic average roughness Ra of the surface of the λ / 4 retardation film used in the present invention is preferably 2.0 nm to 4.0 nm, more preferably 2.5 nm to 3.5 nm.

(Tension softening point)
The λ / 4 retardation film used in the present invention is required to withstand use in a higher temperature environment, and the tension softening point of the λ / 4 retardation film may be 105 ° C. to 145 ° C. If it shows sufficient heat resistance, it is preferable, and 110 to 130 degreeC is especially preferable.

  As a specific method for measuring the tension softening point, for example, using a Tensilon tester (produced by ORIENTEC, RTC-1225A), a sample film is cut out at 120 mm (length) × 10 mm (width) and pulled with a tension of 10 N. However, the temperature can be continuously increased at a temperature increase rate of 30 ° C./min, and the temperature at 9 N can be measured three times, and the average value can be obtained.

(Dimensional change rate)
When the λ / 4 retardation film used in the present invention is used in the organic EL display device of the present invention, there are problems such as unevenness, a change in retardation value, a decrease in contrast, and uneven color due to a dimensional change of the film due to moisture absorption. In order not to generate it, the dimensional change rate (%) of the λ / 4 retardation film is preferably less than 0.5%, and more preferably less than 0.3%.

The rate of dimensional change was determined by measuring the dimensions of the film after being stored for a certain period of time at 23 ° C. and 80% RH and 23 ° C. and 20% RH; the amount of dimensional change represented by these differences was 23 ° C. and 55% RH. It is calculated | required as a ratio with respect to the dimension of the film after a fixed time storage. Specifically, the dimensional change rate can be calculated by the following equation.
Dimensional change rate (%) = {(film size after storage at 23 ° C. and 80% RH−film size after storage at 23 ° C. and 20% RH) / (film size after storage at 23 ° C. and 55% RH) } × 100

(Fault tolerance)
The λ / 4 retardation film used in the present invention preferably has few failures in the film (hereinafter also referred to as defects), and the defects are caused by rapid evaporation of the solvent in the solution-forming drying process. This refers to foreign matter (foreign matter defect) in the film caused by voids (foaming defects) in the film, foreign matter in the film-forming stock solution, and foreign matters mixed in the film formation.

  Specifically, it is preferable that the number of defects having a diameter of 5 μm or more in the film plane is 1/10 cm square or less. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less.

  The diameter of the defect indicates the diameter when the defect is circular, and when the defect is not circular, the range of the defect is determined by observing with a microscope according to the following method, and is defined as the maximum diameter (diameter of circumscribed circle).

  The range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object. When the defect is a change in the surface shape, such as transfer of a roll flaw or an abrasion, the size is confirmed by observing the defect with the reflected light of a differential interference microscope.

  In addition, when observing with reflected light, if the size of the defect is unclear, aluminum or platinum is deposited on the surface for observation. In order to obtain a film having excellent quality expressed by such a defect frequency with high productivity, it is necessary to filter the polymer solution with high precision immediately before casting, to increase the cleanliness around the casting machine, It is effective to set drying conditions after rolling stepwise and to dry efficiently while suppressing foaming.

  When the number of defects is greater than 1/10 cm square, for example, when the film is tensioned during processing in a later process, the film may break with the defects as a starting point, and productivity may decrease. Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.

(Elongation at break)
In addition, the λ / 4 retardation film used in the present invention preferably has a breaking elongation of at least 10%, more preferably 20% or more in at least one direction in the measurement based on JIS-K7127-1999. It is.

  The upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.

(Total light transmittance)
The λ / 4 retardation film of the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film. Also, reduce the surface roughness of the film surface by reducing the surface roughness of the film contact part (cooling roll, calender roll, drum, belt, coating substrate in solution casting, transport roll, etc.) during film formation. It is effective to reduce the diffusion and reflection of light on the film surface.

[Formation method of λ / 4 retardation film]
The λ / 4 retardation film used in the present invention can be formed according to a known method. Hereinafter, typical solution casting methods and melt casting methods will be described.

(Solution casting method)
The λ / 4 retardation film used in the present invention can be produced by a solution casting method. In the solution casting method, a dope is prepared by dissolving a resin such as cellulose ester and an additive such as compound (A) in a solvent, and the dope is cast on a belt-shaped or drum-shaped metal support. It is carried out by a step, a step of drying the cast dope as a web, a step of peeling from the metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished film.

(Organic solvent)
Organic solvents that dissolve cellulose esters and are useful for forming cellulose ester solutions or dopes include chlorinated organic solvents and non-chlorinated organic solvents. Methylene chloride (methylene chloride) can be mentioned as a chlorinated organic solvent, and it is suitable for dissolving cellulose esters, particularly cellulose triacetate. Due to recent environmental problems, the use of non-chlorine organic solvents has been studied. Examples of the non-chlorine organic solvent include methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1, Examples include 1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, and the like. When these organic solvents are used for cellulose triacetate, a dissolution method at room temperature can be used, but an insoluble material can be obtained by using a dissolution method such as a high-temperature dissolution method, a cooling dissolution method, or a high-pressure dissolution method. Can be reduced, which is preferable. Methylene chloride can be used for cellulose esters other than cellulose triacetate, but methyl acetate, ethyl acetate, and acetone are preferably used. Particularly preferred is methyl acetate. In the present invention, an organic solvent having good solubility with respect to the cellulose ester is referred to as a good solvent, and has a main effect on dissolution, and an organic solvent used in a large amount among them is a main (organic) solvent or a main ( Organic) solvent.

  The dope used in the present invention preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent. After dope is cast on a metal support, the solvent begins to evaporate, and when the alcohol ratio increases, the dope film (web) gels, making the web strong and easy to peel off from the metal support. It is used as a solvent, and when these ratios are small, it also has a role of promoting dissolution of a cellulose ester of a non-chlorine organic solvent. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, ethanol is preferred because it has excellent dope stability, has a relatively low boiling point, and has good drying properties. These organic solvents are called poor solvents because they are not soluble in cellulose esters alone.

  It is preferable that the concentration of the cellulose ester in the dope is adjusted to 15 to 30% by mass and the dope viscosity is adjusted to a range of 100 to 500 Pa · s in order to obtain good film surface quality.

  Additives added to the dope include a plasticizer, a retardation adjusting agent, an antioxidant, a deterioration preventing agent, a release agent, in addition to the compound (A), an ultraviolet absorber having an OH group, and a retardation value increasing agent. There are auxiliary agents, surfactants, dyes, fine particles and the like. In the present invention, additives other than fine particles may be added during the preparation of the cellulose ester solution, or may be added during the preparation of the fine particle dispersion.

  It is preferable that the cellulose resin used in the present invention has a small amount of bright spot foreign matter when formed into a film. A bright spot foreign material is an arrangement of two polarizing plates orthogonally (crossed Nicols), a cellulose resin film placed between them, and the light from the light source applied from one side, and the cellulose resin film from the other side. This is the point where the light from the light source appears to leak when observed. At this time, the polarizing plate used for the evaluation is desirably composed of a protective film having no bright spot foreign matter, and a polarizing plate using a glass plate for protecting the polarizer is preferably used. The cause of bright spot foreign matter is considered to be one of the causes of unacetylated or low acetylated cellulose contained in the cellulose resin. Use a cellulose resin with few bright spot foreign substances and filter the molten cellulose resin or cellulose resin solution. In at least one of the latter process of synthesizing the cellulose resin and the process of obtaining the precipitate, it is possible to remove the bright spot foreign matters through the filtration process in the same manner once in the solution state. Since the molten resin has a high viscosity, the latter method is more efficient.

As the film thickness decreases, the number of bright spot foreign matters per unit area decreases, and the bright spot foreign substances tend to decrease as the content of the cellulose resin contained in the film decreases. The bright spot foreign matter preferably has a bright spot diameter of 0.01 mm or more and 200 pieces / cm ² or less, most preferably none. Moreover, it is preferable that it is 200 pieces / cm < ² > or less also about a bright spot of 0.005-0.01 mm or less, and it is most preferable that there is nothing at all.

  When removing bright spot foreign matter by filtration, filtering a cellulose resin composition (also referred to as a dope) to which a plasticizer, an ultraviolet absorber, an antioxidant, a stabilizer and the like are added and mixed rather than filtering the cellulose resin alone. However, it is preferable because the removal efficiency of bright spot foreign matter is high. Of course, the cellulose resin may be dissolved in a solvent during the synthesis and reduced by filtration. As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, and fluorine resins such as tetrafluoroethylene resin are preferably used, and ceramics and metals are particularly preferably used. The absolute filtration accuracy is preferably 50 μm or less, more preferably 5 μm or less. These can be used in combination as appropriate. The filter medium can be either a surface type or a depth type, but the depth type is preferably used because it is relatively less clogged.

  The concentration of cellulose acetate in the dope is preferably higher because the drying load after casting on a metal support can be reduced. However, if the concentration of cellulose acetate is too high, the load during filtration increases and the filtration accuracy increases. Becomes worse. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%. The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.

  The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is set to −50 ° C. to a temperature at which the solvent boils and does not foam. A higher temperature is preferable because the web can be dried faster, but if it is too high, the web may foam and flatness may deteriorate.

  The preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short.

  When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. .

  In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  In order for the λ / 4 retardation film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 60%. It is 130 mass%, Most preferably, it is 20-30 mass% or 70-120 mass%.

  Moreover, in the drying process of the obtained web, it is preferable that the web is peeled from the metal support and further dried to make the residual solvent amount 1% by mass or less, more preferably 0.1% by mass or less. Yes, particularly preferably 0 to 0.01% by mass or less.

  In the web drying process, a roll drying method (a method in which webs are alternately passed through a plurality of upper and lower rolls) and a method in which the web is dried by a tenter method are generally employed.

(Stretching process)
The λ / 4 retardation film used in the present invention has an in-plane retardation Ro (550) measured at a wavelength of 550 nm in the range of 100 to 170 nm. The retardation is preferably applied by stretching the web.

  There is no particular limitation on the stretching method. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination. That is, the film may be stretched in the transverse direction, longitudinally, or in both directions with respect to the film forming direction, and when stretched in both directions, simultaneous stretching or sequential stretching may be used. May be. In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

  In the present invention, in particular, stretching is performed in the transport direction using the difference in peripheral speed of the film transport roll, or both ends of the web are gripped with clips or the like in the direction perpendicular to the transport direction (also referred to as the width direction or the TD direction). It is preferable to use a tenter method, and it is also preferable to use a tenter that can independently control the web gripping length (distance from the start of gripping to the end of gripping) by the left and right gripping means.

  Further, in order to set the orientation angle θ of the λ / 4 retardation film used in the present invention with respect to the film longitudinal direction to 35 to 55 °, the web is stretched in the direction of 45 ° with respect to the conveying direction in the stretching step. It is preferable.

  As described above, a roll-shaped polarizing film having a transmission axis in a direction parallel to the longitudinal direction of the slow axis and a λ / 4 retardation film having an orientation angle of substantially 45 ° are aligned with each other in the longitudinal direction. When pasted with a to-roll, a roll-like long circularly polarizing plate can be easily produced, which is advantageous in production with less film cut loss.

  Hereinafter, a method of stretching in the 45 ° direction will be described.

  In order to obliquely stretch the web in a direction substantially 45 ° with respect to the longitudinal direction, it is preferable to use the tenter shown in FIG. FIG. 2 is a schematic diagram showing oblique stretching by a tenter. In the same figure, 27-1 shows the conveyance direction of a film.

  The stretched film is produced using a tenter. As shown in FIG. 2, this tenter moves the film 21 fed from a film roll (feeding roll) 28-1 in the traveling direction (moving direction of the middle point in the film width direction) in an oven heating environment. On the other hand, it is a device that widens in an oblique direction. The tenter includes an oven (not shown), a pair of rails 24 on the left and right of which a gripping tool for transporting the film travels, and a number of gripping tools (not shown) that travel on the rails. Grasping both ends of the unstretched film (web) 21 fed out from the film roll 28-1 and sequentially supplied to the entrance of the tenter with gripping tools 22-1 and 22-2, guiding the film into the oven, The film is released from the grippers 25-1 and 25-2 at the exit of the tenter. The stretched film 26 released from the gripping tools 25-1 and 25-2 is conveyed by the film roll 28-2 and wound around a core (not shown). The pair of rails 24 have endless continuous tracks 23-1 and 23-2, respectively, and the gripping tools that have released the grip of the film 26 at the exit portion of the tenter travel outside and are sequentially returned to the entrance portion. It is like that.

  The rail shape of the tenter is asymmetrical on the left and right according to the orientation angle, stretch ratio, etc. given to the stretched film to be manufactured, and can be finely adjusted manually or automatically. In the present invention, a long film is stretched, and the orientation angle θ can be set to an arbitrary angle within the range of 10 ° to 80 ° with respect to the winding direction after stretching. In the present invention, the gripping tool of the tenter is configured to travel at a constant speed with a certain distance from the front and rear gripping tools.

  FIG. 3 is a schematic diagram showing a rail track (rail pattern) of a tenter used for oblique stretching. As shown in FIG. 3, the feeding direction DR1 of the film (web) before stretching is different from the winding direction (MD direction) DR2 of the film after stretching, and thereby stretching with a relatively large orientation angle. Even in a film, it is possible to obtain a wide and uniform optical characteristic. The feeding angle θi is an angle formed by the feeding direction DR1 of the film before stretching and the winding direction DR2 of the film after stretching. In the present invention, for example, in order to produce a film having an orientation angle of 40 ° to 80 °, the feeding angle θi is set to 10 ° <θi <60 °, preferably 15 ° <θi <50 °. By setting the feeding angle θi in the above range, the variation in the optical characteristics in the width direction of the obtained film becomes good (becomes small).

  The film fed from the film roll (feeding roll) is gripped at both ends (both sides) by the left and right gripping tools at the tenter entrance (position a), and travels as the gripping tool travels. The left and right grips CL and CR, which are opposed to the direction of the film traveling direction (feeding direction DR1) at the tenter entrance (position a), run on a rail that is asymmetrical to the left and right, and are in a preheating zone. Through an oven having a stretching zone and a heat setting zone. Here, “substantially perpendicular” indicates that the angle formed by the straight line connecting the aforementioned gripping tools CL and CR and the film feeding direction DR1 is within 90 ± 1 °.

  The preheating zone refers to a section in which the vehicle travels while maintaining a constant interval between the gripping tools gripping both ends at the oven entrance. The stretching zone refers to an interval until the gap between the gripping tools gripping both ends starts to become constant again. In addition, the cooling zone refers to a section in which the temperature in the zone is set to be equal to or lower than the glass transition temperature Tg ° C. of the thermoplastic resin constituting the film during a period in which the interval between the gripping tools after the stretching zone becomes constant again. .

  The temperature of each zone is set to Tg + 5 to Tg + 20 ° C., the temperature of the stretching zone is set to Tg to Tg + 20 ° C., and the temperature of the cooling zone is set to Tg−30 to Tg ° C. with respect to the glass transition temperature Tg of the thermoplastic resin. It is preferable to do.

  The draw ratio R (W / Wo) in the drawing step is preferably 1.3 to 3.0 times, more preferably 1.5 to 2.8 times. When the draw ratio is within this range, thickness unevenness in the width direction is reduced, which is preferable. In the stretching zone of the tenter stretching machine, if the stretching temperature is differentiated in the width direction, the thickness unevenness in the width direction can be further improved. In addition, Wo represents the width of the film before stretching, and W represents the width of the film after stretching.

  The step of stretching in the oblique direction may be performed within the film forming step (online), or may be unwound after being wound up and stretched by the tenter (offline).

  The means for drying the cellulose acetate film is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the drying step of the cellulose acetate film is preferably an effective heat treatment of the glass transition point of the film of −5 ° C. or lower and 100 ° C. or higher and 10 minutes or longer and 60 minutes or shorter. Drying is performed at a drying temperature of 100 to 200 ° C, more preferably 110 to 160 ° C.

  After the predetermined heat treatment, it is preferable to provide a slitter and cut off the end portion before winding to obtain a good winding shape. Furthermore, it is preferable to knurling both ends of the width.

  The knurling process can be formed by pressing a heated embossing roll. Fine embossing is formed on the embossing roll, and the embossing roll can be pressed to form asperity on the film and make the end bulky.

  The height of the knurling at both ends of the width of the film obtained after stretching is preferably 4 to 20 μm and the width is 5 to 20 mm.

  In the present invention, the knurling process is preferably provided after the drying in the film forming process and before winding.

(Melting method)
The λ / 4 retardation film used in the present invention may be formed by a melt film forming method. The melt film-forming method refers to heating and melting a composition containing an additive such as a resin and a plasticizer to a temperature exhibiting fluidity, and then casting a melt containing fluid cellulose acetate.

  More specifically, the heat melting molding method can be classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these molding methods, the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy. It is preferable that a plurality of raw materials used for melt extrusion are usually kneaded in advance and pelletized.

  Pelletization may be performed by a known method. For example, dry cellulose acetate, a plasticizer, and other additives are fed to an extruder with a feeder and kneaded using a single-screw or twin-screw extruder, and formed into a strand form from a die. It can be done by extrusion, water cooling or air cooling and cutting.

  The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.

  A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

  The extruder is preferably processed at as low a temperature as possible so as to be able to be pelletized so that the shear force is suppressed and the resin does not deteriorate (decrease in molecular weight, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. Of course, the raw material powder can be directly fed to the extruder by a feeder without being pelletized to form a film as it is.

  Using a single or twin screw extruder, the pellets are melted at a temperature of about 200 to 300 ° C., filtered through a leaf disk filter, etc. to remove foreign matter, and then formed into a film from a T die. The film is nipped by a cooling roll and an elastic touch roll, and solidified on the cooling roll.

  When introducing from the supply hopper to the extruder, it is preferable to prevent oxidative decomposition or the like under vacuum, reduced pressure, or inert gas atmosphere.

  The extrusion flow rate is preferably performed stably by introducing a gear pump or the like. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances. The stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.

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

  The film temperature on the touch roll side when the film is nipped between the cooling roll and the elastic touch roll is preferably Tg or more and Tg + 110 ° C. or less of the film. A well-known roll can be used for the roll which has the elastic body surface used for such a purpose.

  The elastic touch roll is also called a pinching rotator. As the elastic touch roll, a commercially available one can be used.

  When peeling the film from the cooling roll, it is preferable to control the tension to prevent deformation of the film.

  Moreover, it is preferable that the film obtained as described above is stretched by the stretching operation after passing through the step of contacting the cooling roll.

  As a method of stretching, a known roll stretching machine or tenter can be preferably used. The stretching temperature is usually preferably performed in the temperature range of Tg to Tg + 60 ° C. of the resin constituting the film.

  Prior to winding, the ends may be slit and cut to the width of the product, and knurling (embossing) may be applied to both ends to prevent sticking or scratching during winding. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. In addition, since the film has deform | transformed and cannot use as a product normally, the holding | grip part of the clip of both ends of a film is cut out and reused.

  The obtained λ / 4 retardation film has a width of 1 to 4 m. In particular, those having a width of 1.4 to 4 m are preferably used, and particularly preferably 1.6 to 3 m. If it exceeds 4 m, conveyance becomes difficult.

  Thus, the λ / 4 retardation film used in the present invention is a web (film original) containing cellulose ester, the aforementioned compound (A), an ultraviolet absorber having an OH group, and a retardation value increasing agent. Is obtained through a stretching step. Thus, compatibility of a compound (A) and a cellulose ester can be improved by selecting a compound (A) as a wavelength dispersion regulator. Moreover, the said ultraviolet absorber and a compound (A) can be made to interact by selecting the ultraviolet absorber which has OH group as a ultraviolet absorber. By these, when extending | stretching a web, precipitation of additives, such as a compound (A) and a ultraviolet absorber, can be suppressed. Furthermore, since the web (film raw film) contains a retardation value increasing agent, the draw ratio can be lowered. Thereby, precipitation of additives, such as a compound (A) and a ultraviolet absorber at the time of extending | stretching a web, can be suppressed more. As a result, it is considered that white turbidity of the obtained λ / 4 retardation film can be suppressed.

  Moreover, it is thought that the environmental fluctuation | variation of the phase difference value of the (lambda) / 4 phase difference film obtained can be reduced as a result of suppressing precipitation of additives, such as a compound (A) and a ultraviolet absorber. Moreover, since the λ / 4 retardation film produced at a low draw ratio has little dimensional change, it can be considered that the environmental fluctuation of the retardation value can be suppressed thereby.

[Polarizer]
As the polarizer constituting the organic EL display device of the present invention shown in FIG. 1, any appropriate polarizer can be adopted depending on the purpose. For example, a dichroic substance such as iodine or a dichroic dye is adsorbed on a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film or an ethylene / vinyl acetate copolymer partially saponified film. Examples include uniaxially stretched films, polyene-based oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of these polarizers is not particularly limited, but is generally about 1 to 80 μm.

  A polarizer uniaxially stretched by adsorbing iodine to a polyvinyl alcohol film can be produced by, for example, dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing.

  By washing the polyvinyl alcohol film with water, not only can the surface of the polyvinyl alcohol film be cleaned and the anti-blocking agent can be washed, but also the effect of preventing unevenness such as uneven dyeing can be obtained by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

〔Protective film〕
The protective layer of the circularly polarizing plate of the present invention is preferably a protective film (protective film 11 in FIG. 1), such as a triacetyl cellulose film, a cellulose acetate propionate film, a cellulose diacetate film, and a cellulose acetate butyrate film. Cellulose ester film, polyester film such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyethylene film, polypropylene film, cellophane, polyvinylidene chloride film, Polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, norbornene resin Films, polymethylpentene films, polyether ketone films, polyether ketone imide film, a polyamide film, a fluorine resin film, nylon film, can be used cycloolefin polymer film, a polymethyl methacrylate film or an acrylic film or the like.

  Among these, cellulose ester films (for example, Konica Minoltac KC8UX, KC4UX, KC4UA, KC6UA, KC4CZ, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC4UE, KC4R ), A polycarbonate film, a cycloolefin polymer film, and a polyester film are preferable. In the present invention, a cellulose ester film is preferable from the viewpoints of optical properties, productivity, and cost.

  The protective film preferably has an in-plane maximum elastic modulus of 4.0 GPA or more in an environment of 23 ° C. and 55 RH% because the panel deflection can be further suppressed. In the same manner as the production of the λ / 4 retardation film, the selection of cellulose acetate, the use of the compound represented by the general formula (A), the use of other additives, the stretching conditions, and the like are controlled, and a high elastic modulus is obtained. The protective film which has can be produced.

  In the case of an organic EL display device for 3D image display, disposing λ / 4 retardation films on both sides of the polarizer has an effect on improving the quality of the display image. Therefore, it is also preferable to use the λ / 4 retardation film used in the present invention as the protective film according to the present invention. At that time, the direction of the maximum elastic modulus in the surface of the protective film is in the direction of 35 ° to 55 ° with respect to the longitudinal direction of the screen of the image display device, and the maximum in the surface of the λ / 4 retardation film. By making it parallel to the direction of the elastic modulus, a high-quality organic EL display device for 3D image display can be obtained.

(Antireflection layer)
It is also preferable to provide an antireflection layer having an external light antireflection function directly or via another layer on the protective film of the circularly polarizing plate.

  The antireflection layer is preferably laminated in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so that the reflectance is reduced by optical interference. The antireflection layer is preferably composed of a low refractive index layer having a refractive index lower than that of the support, or a combination of a high refractive index layer having a refractive index higher than that of the support and a low refractive index layer. Particularly preferably, it is an antireflection layer composed of three or more refractive index layers, and three layers having different refractive indexes from the support side are divided into medium refractive index layers (high refractive index layers having a higher refractive index than the support). Are preferably laminated in the order of a layer having a lower refractive index) / a high refractive index layer / a low refractive index layer. Alternatively, an antireflection layer having a layer structure of four or more layers in which two or more high refractive index layers and two or more low refractive index layers are alternately laminated is also preferably used. Although the following structure can be considered as a structure of an antireflection layer, it is not limited to this.

Protective film / Low refractive index layer Protective film / Medium refractive index layer / Low refractive index layer Protective film / Medium refractive index layer / High refractive index layer / Low refractive index layer Protective film / High refractive index layer (conductive layer) / Low Refractive index layer

[Curing layer]
The circularly polarizing plate of the present invention is preferably sandwiched between a polarizer, a λ / 4 retardation film and a protective film, and a cured layer is laminated on the viewing side of the protective film. Since the amount of warpage and the direction of warpage can be adjusted by the material, thickness and degree of cure of the cured layer, it is preferable because warpage of the circularly polarizing plate can be prevented.

  It is preferable that an antireflection layer is further provided on the viewing side of the cured layer. The antireflection layer can prevent the contrast of the image from being lowered due to the reflection of external light on the surface of the protective film or the cured layer.

  The circularly polarizing plate of the present invention can be produced by cutting a long roll having a long protective film, a long polarizer and a long λ / 4 retardation film in this order. The long λ / 4 retardation film contains cellulose acetate that satisfies the condition defined by the formula (1) and a compound represented by the general formula (A). By applying the circularly polarizing plate of the present invention including such a λ / 4 retardation film to an organic EL display device, an effect of shielding the specular reflection of the metal electrode of the organic EL light-emitting body is exhibited.

  Further, as described above, by obliquely stretching the web (film raw film), the angle of the slow axis (that is, the orientation angle θ) of the λ / 4 retardation film of the present invention is “substantially” with respect to the longitudinal direction. 45 degrees ". As a result, the direction of the in-plane maximum elastic modulus is also “substantially 45 °” with respect to the longitudinal direction, and the circularly polarizing plate tends to bend in an oblique direction.

  The circularly polarizing plate of the present invention preferably includes a polarizer, a λ / 4 retardation film disposed on one surface thereof, and a protective film disposed on the other surface; the viewing side of the protective film It is preferable that a hardened layer is further laminated on the substrate because it has an effect of preventing warpage of the circularly polarizing plate.

  In addition, the organic EL display device of the present invention requires that the circularly polarizing plate of the present invention has an ultraviolet absorption function in order to prevent deterioration due to ultraviolet rays. It is preferable that the protective film on the viewing side (protective film 11 in FIG. 1) has an ultraviolet absorbing function from the viewpoint that both the polarizer and the organic EL element can exhibit a protective effect against ultraviolet rays. Furthermore, when the λ / 4 retardation film on the light emitter side (λ / 4 retardation film 9 in FIG. 1) also has an ultraviolet absorbing function, the deterioration of the organic EL element can be further suppressed.

〔substrate〕
The substrate 1 constituting the organic EL element B shown in FIG. 1 is not particularly limited in the type such as glass and plastic, and may be transparent or opaque. When light is extracted from the substrate 1 side, the substrate 1 is preferably transparent. Examples of the transparent substrate preferably used include glass, quartz, and a transparent resin film.

(Resin film)
Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both may be formed. Water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24h · atm) or less, and further measured by a method according to JIS K 7126-1987. A high barrier film having an oxygen permeability of 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less and a water vapor permeability of 1 × 10 ⁻⁵ g / (m ² · 24 h · atm) or less. Preferably there is.

  As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

  The method for forming the barrier film is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

  Examples of the opaque substrate include a metal plate such as aluminum and stainless steel, a film, an opaque resin substrate, a ceramic substrate, and the like.

(Glass plate)
The substrate is preferably a glass plate from the viewpoint of preventing warpage of the organic electroluminescence display device. The thickness of the glass plate is preferably from 0.1 mm to 10 mm. If it is 0.1 mm or more, durability is good, it is not cracked during transportation, it is not cracked by a weak impact during use, and it does not warp even when heated, and there is no deterioration in visibility due to cracking. . Moreover, if it is 10 mm or less, the mass of an organic electroluminescent display apparatus can be made light and manufacturing cost can also be held down.

  In the following, the invention will be described in more detail with reference to examples. These examples do not limit the scope of the present invention.

[Production of λ / 4 Retardation Film 101]
The following components were stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to obtain a fine particle dispersion 1.
(Composition of fine particle dispersion 1)
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.): 11 parts by mass Ethanol: 89 parts by mass

Next, the fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. The obtained solution was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle addition solution 1.
(Composition of fine particle additive liquid 1)
Methylene chloride: 99 parts by mass Fine particle dispersion 1: 5 parts by mass

Next, a main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Then, cellulose acetate, triphenyl phosphate as a plasticizer, biphenyl diphenyl phosphate, tinuvin 928 (manufactured by BASF Japan Ltd.) and a fine particle additive solution 1 as a UV absorber are stirred in a pressure dissolution tank containing a solvent. While throwing. This was heated and dissolved completely with stirring. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. The main dope solution was prepared by filtration using 244.
(Main dope composition)
Cellulose acetate having an acetyl group substitution degree of 3.0: 100 parts by weight Triphenyl phosphate (plasticizer): 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer): 3.9 parts by weight Methylene chloride (first solvent): 336 parts by weight Methanol (second solvent): 30 parts by mass Ultraviolet absorber (Tinubin 928 (manufactured by BASF Japan Ltd.)): 2.3 parts by mass Particulate additive solution 1: 1 part by mass

The following materials were put into another mixing tank and stirred while heating to prepare a liquid for a phase difference increasing agent.
(Composition of liquid for retardation increasing agent)
Compound A-1: 14 parts by mass Compound B-1: 12 parts by mass Methylene chloride: 92 parts by mass Methanol: 8 parts by mass

  Then, 474 parts by mass of the main dope solution was mixed with 25 parts by mass of the retardation value increasing agent solution, and sufficiently stirred to prepare a dope solution.

In addition, as the compounds A-1 to A-4, the compounds B-1 to B-2, and the ultraviolet absorbers, the above exemplified compounds were used, and the following compounds were used as the comparative compounds-1 to 4.

  Next, using the endless belt casting apparatus, the obtained dope solution was uniformly cast on a stainless steel belt support at a temperature of 33 ° C. and a width of 2000 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

  On the stainless steel belt support, the solvent was evaporated until the amount of residual solvent in the cast film was 75%. Subsequently, the obtained film was peeled off from the stainless steel belt support with a peeling tension of 130 N / m to produce a raw film.

  Using the apparatus described in Example 1 of JP-A-2009-214441 and the apparatus described in FIG. 1 (apparatus in FIG. 3 of the present specification), the produced raw film was delayed at a temperature of 185 ° C. and a magnification of 1.6 times. Stretching was performed in an oblique direction so that the axis formed 45 ° with the film width direction.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m. As described above, a λ / 4 retardation film 101 having a dry film thickness of 40 μm was obtained.

[Production of λ / 4 retardation films 102 to 108 and 201 to 212]
The λ / 4 retardation films 102 to 108 and 201 to 212 were produced in the same manner as the λ / 4 retardation film 101 except that the composition was changed as prescribed in Table 1.

  However, in producing the λ / 4 retardation films 107, 108, 209, and 210, the stretching conditions of the original film in Example 1 were changed as shown in Table 2. Other than that was produced in the same manner as the λ / 4 retardation film 101.

[Production of λ / 4 Retardation Film 211]
It produced according to the paragraphs 0085-0086 of patent 4681334. That is, a sodium hydroxide aqueous solution and ion-exchanged water were charged into a reactor equipped with a stirrer, a thermometer, and a reflux condenser, and bisphenol A and biscresol fluorene were dissolved at a ratio of 36:64 (mol%). A small amount of hydrosulfide was added.

  Next, methylene chloride was added thereto, and phosgene was blown in at about 20 ° C. over about 60 minutes. Further, p-tert-butylphenol was added for emulsification, triethylamine was added, and the mixture was stirred at 30 ° C. for about 3 hours to complete the reaction. After completion of the reaction, the organic phase was separated and the methylene chloride was evaporated to obtain a copolymerized polycarbonate. The composition ratio of the obtained copolymer polycarbonate was almost equal to the monomer charge.

  The copolymer polycarbonate had a glass transition temperature (Tg) of 223 ° C. and a photoelastic constant of 43 Brewster.

  This copolymer polycarbonate was dissolved in methylene chloride to prepare an 18% by mass dope solution. This dope solution was cast on a steel drum. Next, the obtained film was continuously peeled off and dried, and then longitudinally uniaxially stretched at a magnification of 2.2 times in the longitudinal direction (MD direction) at 228 ° C. with a roll stretching machine. The thickness of the obtained longitudinally uniaxially stretched film was 50 μm, and the residual solvent amount was 0.2% by mass. Further, as shown in Table 3, the optical characteristics of the λ / 4 retardation film were Ro (550) = 138 nm and Rth (550) = 70 nm.

[Production of λ / 4 Retardation Film 212]
It was produced with reference to paragraphs 0077 to 0078 of JP2010-204224A. That is, pellets of thermoplastic resin P1 (trade name “ZEONOR 1420”, manufactured by Nippon Zeon Co., Ltd., norbornene resin) were melted by an extruder and discharged from an extrusion die to form a raw film.

  Next, the raw film was stretched obliquely with a tenter stretching machine at a stretching temperature of 147 ° C. and a stretching ratio of 2.1 times so that the slow axis was inclined at 45 ° with respect to the longitudinal direction. Thereby, a long cycloolefin polymer film was obtained.

  The optical characteristics of the λ / 4 retardation films 211 and 212 were Ro = 138 nm and Rth (550) = 70 nm as shown in Table 3 below.

[Production of λ / 4 retardation films 109 to 115 and 213 to 220]
The λ / 4 retardation films 109 to 115 and 213 to 220 were prepared in the same manner as the λ / 4 retardation film 101 except that the composition was changed as prescribed in Table 3.

  However, in producing the λ / 4 retardation films 114, 115, 219, and 220, the stretching conditions of the original film in Example 1 were changed as shown in Table 4. Other than that was produced in the same manner as the λ / 4 retardation film 109.

The compositions of λ / 4 retardation films 101-108 and 201-212 are shown in Table 1; their production conditions are shown in Table 2. The compositions of λ / 4 retardation films 109-115 and 213-220 are shown in Table 3; their production conditions are shown in Table 4.

  The retardation value, average refractive index and haze of the obtained retardation film were measured by the following methods. The results are shown in Tables 5 and 6 below.

(Measurement of phase difference value)
About the produced (lambda) / 4 phase difference film, the Ro retardation value and Rth retardation value in wavelength 550nm were measured using the ellipsometer (M-150, JASCO Corporation make).

(Measurement of average refractive index)
The refractive index of the produced λ / 4 retardation film in the triaxial direction (x-axis direction in the film plane, y-axis direction perpendicular to the film plane, z-axis direction parallel to the normal of the film plane) at a measurement wavelength of 550 nm, Measurement was performed using an Abbe refractometer, and the average value thereof was defined as “average refractive index”.

(Measurement of haze)
The haze of the produced λ / 4 retardation film was measured using a haze meter (NDH1001-DP, manufactured by Nippon Denshoku Industries Co., Ltd.). For haze, an average value of five arbitrary measured values was adopted.

[Preparation of Protective Film 1]
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, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L equipped with a thermometer, stirrer and slow cooling tube The temperature was gradually raised while stirring until it reached 230 ° C. in a nitrogen stream. The ester compound 1 was obtained by making it dehydrate-condense for 15 hours, and depressurizingly distilling unreacted 1, 2- propylene glycol at 200 degreeC after completion | finish of reaction. The acid value of the ester compound 1 was 0.10 mgKOH / g and the number average molecular weight was 450.

Preparation of dope solution The following components were put into a sealed container, heated, and completely dissolved while stirring. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. No. 24 was used for filtration to prepare a dope solution.
(Dope solution composition)
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 aforementioned fine particle additive solution 1: 4 parts by mass Methylene chloride: 432 parts by mass Ethanol: 38 parts by mass

Film Formation Next, the obtained dope solution was uniformly cast on a stainless steel band support using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, and the stainless steel band support was peeled off. The cellulose ester film web was evaporated at 35 ° C., slit to 1.65 m width, 30% in the TD direction (film width direction) with a tenter while applying heat at 160 ° C., and 1% in the MD direction. Stretched at a magnification. The residual solvent amount when starting stretching was 20%. Then, after drying for 15 minutes while transporting the inside of a drying device at 120 ° C. with a number of rolls, slitting to a width of 1.49 m, applying a knurling process with a width of 15 mm and a height of 10 μm at both ends of the film, and winding it around a winding core The protective film 1 was obtained. The residual solvent amount of the protective film 1 was 0.2%, the film thickness was 40 μm, and the number of turns was 3900 m.

  As a result of measuring the orientation angle θ of the protective film 1 using KOBRA-21ADH manufactured by Oji Scientific Instruments, it was in the range of 90 ° ± 1 ° with respect to the longitudinal direction of the film.

[Production of Circular Polarizing Plates 101 to 115, 201 to 220]
A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times).

  The obtained film was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. consisting of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. The obtained film was washed with water and dried to obtain a polarizer.

  The produced λ / 4 retardation films 101 to 115 and 201 to 220 were bonded to one surface of the polarizer using a completely saponified polyvinyl alcohol 5% aqueous solution as an adhesive. In that case, it bonded so that the angle which the transmission axis of a polarizer and the slow axis of a (lambda) / 4 phase difference film make might be 45 degree | times. The protective film 1 was similarly subjected to alkali saponification treatment and bonded to the other surface of the polarizer to produce circularly polarizing plates 101 to 115 and 201 to 220.

  For the λ / 4 retardation films 209, 210, 219 and 220, the λ / 4 retardation film was not subjected to saponification treatment, and after applying an acrylic adhesive to the λ / 4 retardation film, a polarizer It was produced in the same manner as above except that it was attached to.

[Production of organic EL cells]
Using an alkali-free glass for 50 inches (127 cm) having a thickness of 3 mm, an organic EL having the configuration described in FIG. 8 of the same publication according to the method described in the example of JP 2010-20925 A A cell was produced.

[Production of organic EL display device]
An adhesive was applied to the surface of the λ / 4 retardation film of each circularly polarizing plate prepared above, and then bonded to the viewing side of the organic EL cell to prepare an organic EL display device.

[Evaluation of organic EL display devices]
Each of the organic EL display devices produced above was evaluated as follows. The evaluation results are shown in Tables 5 and 6.

(Hue change over time)
The deterioration of the blue light-emitting layer was measured for an organic EL display device irradiated with an ultraviolet irradiation device at 100 mW / m ² for 1 hour and an unirradiated organic EL display device. Only in the blue light emitting layer, the current value was set so that the initial light amount was 300 cd / m ^2, and the light amount was measured every hour in the state where the current value was maintained. The time until the light amount reaches 150 cd / m ² is 200 hours or more earlier than the unirradiated organic EL display device, or the initial light amount does not reach 300 cd / m ² The sample was “×”, “△” when 100 hours or more and less than 200 hours, and “◯” when less than 100 hours.

(Light extraction efficiency)
Apart from the organic EL display device prepared above, a reference organic EL display device prepared in the same manner except that the λ / 4 retardation film was replaced with the protective film 1 was prepared. Then, the brightness of the image of the organic EL display device when the image was displayed was evaluated according to the following criteria.
○: The brightness of the image of the organic EL display device produced as described above is not visually changed compared to the reference organic EL display device.
X: The brightness of the organic EL display device image produced as described above is lower than that of the reference organic EL display device.

(Anti-reflection function on the front)
The presence or absence of a background reflection when an image was displayed on the organic EL display device produced above was evaluated according to the following criteria.
○: When viewing the produced organic EL display device, the image of itself and the background are not so visible.
X: When viewing the produced organic EL display device, the image of the user and the background can be clearly seen together with the image of the display device.

(Image environment fluctuation)
Each organic EL display device was evaluated with a temperature impact tester in an environment of 23 ° C 55% RH, 23 ° C 20% RH, and 23 ° C 80% RH. went. Based on the environment of 23 ° C. and 55% RH, the evaluation was performed as follows.
○: No change is observed in the image and the antireflection effect in the environment of 23 ° C. and 20% RH and in the environment of 23 ° C. and 80% RH compared with the environment of 23 ° C. and 55% RH.
Δ: A slight change is observed in either the image or the antireflection effect in the environment of 23 ° C. and 20% RH and in the environment of 23 ° C. and 80% RH as compared with the environment of 23 ° C. and 55% RH.
X: A clear change is observed in either the image or the antireflection effect in the environment of 23 ° C. and 20% RH and in the environment of 23 ° C. and 80% RH as compared with the environment of 23 ° C. and 55% RH.

The evaluation results of the λ / 4 retardation films 101 to 108 and 201 to 212 are shown in Table 5; the evaluation results of the λ / 4 retardation films 109 to 115 and 213 to 220 are shown in Table 6.

  As shown in Tables 5 and 6, with respect to λ / 4 retardation films 101 to 104 and 109 to 112 to which compounds A-1 to 4 used in the present invention were added, λ to which comparative compounds 1 to 4 were added / 4 phase difference films 201-204 and 213-216 show that the haze of a film is high. This is because when Comparative Compounds-1 to 4 are added to the film together with the ultraviolet absorber, the compatibility of various additives is reduced, and additives such as Comparative Compounds-1 to 4 are precipitated by high-magnification stretching. It is thought that it is because

  In addition, the λ / 4 retardation films 205 and 217 to which no ultraviolet absorber is added have a large hue change over time, and the evaluation of this characteristic is “x”. This is because the retardation films 205 and 217 do not have ultraviolet absorption capability, and therefore, when the organic EL display device on which the retardation films 205 and 217 are disposed is exposed to light containing ultraviolet rays, the amount of light emitted from the blue light emitting element is reduced. .

  Furthermore, the λ / 4 retardation film in which the degree of acetyl group substitution of the cellulose ester is within the scope of the present invention has a low haze and no turbidity of the film, whereas λ / 4 retardation films 207 and 208 The haze was high, and the cloudiness of the film was confirmed. This is because the compound A of the present invention is a material compatible with the cellulose ester film as in Patent Document 3, and the λ / 4 retardation film in the present invention that requires high magnification stretching, If the degree of acetyl substitution is not within the range of 2.7 to 3.0, it indicates that haze increases. In general, when a plastic resin is stretched, the degree of crystallinity of the resin is increased, and an additive having low compatibility is precipitated.

  The compound (A) used in the present invention is well compatible with a resin having a cellulose ester having an acetyl substitution degree in the range of 2.7 to 3.0. When the substitution degree is low, the compatibility is lowered. It is considered that the haze of the four retardation films 207 and 208 has increased.

  Since the λ / 4 retardation films 209, 210, 219 and 210 are out of the range of the retardation value specified by the present invention, the antireflection function on the front when placed in the organic EL display device is sufficient in performance. There wasn't. In particular, this is because the in-plane retardation value Ro is out of range.

  Since the λ / 4 retardation films 211 and 212 have a high average refractive index, it can be seen that the light extraction efficiency is low. This is presumably because the backscattering is increased because the average refractive index is high. When the λ / 4 retardation film used in the present invention is disposed in an organic EL display device, the light emitting element side of the film is often in contact with glass or an adhesive, and the average refractive index is 1.5 or less. Is preferable from the viewpoint of suppressing backscattering.

  This application claims priority based on Japanese Patent Application No. 2011-199136 filed on September 13, 2011. The contents described in the application specification and the drawings are all incorporated herein.

  According to the present invention, prevention of precipitation of additives in the λ / 4 retardation film and environmental fluctuation of retardation value are suppressed, high definition, deterioration of image quality, deterioration of hue due to ultraviolet rays, and light extraction efficiency. It is possible to provide an organic EL display device in which the decrease in the brightness is suppressed.

A Organic EL display device B Organic EL element C Circularly polarizing plate 1 Substrate 2 Metal electrode 3 TFT
4 Organic Light-Emitting Layer 5 Transparent Electrode 6 Insulating Layer 7 Sealing Layer 8 Film 9 λ / 4 Retardation Film 10 Polarizer 11 Protective Film 12 Cured Layer 13 Antireflection Layer DR1 Feeding Direction DR2 Winding Direction θi Feeding Angle (with feeding direction) Angle formed by winding direction)
CR, CL Gripping tool Wo Width of the film before stretching W Width of the film after stretching 21 Films 2-1, 22-2, 25-1, 25-2 before stretching Gripping tools 23-1, 23-2 Endless Continuous track 24 A pair of rails 26 Film after stretching 27-1 Film transport direction 28-1, 28-2 Film roll

Claims (5)

An organic EL display device including a light emitting element and a circularly polarizing plate disposed on a viewing side surface of the light emitting element,
The circularly polarizing plate includes a polarizer, a λ / 4 retardation film disposed between the polarizer and the light-emitting element, a protective film disposed on the viewing side of the polarizer, and having ultraviolet absorption performance. Including,
The λ / 4 retardation film includes a cellulose ester having a substitution degree X of acetyl group satisfying the following formula (1), a compound (A) represented by the following formula, an ultraviolet absorber having an OH group, and a retardation. Containing a value raising agent,
Formula (1) 2.7 <= X <= 3.0

(R1, R2, R3, R4 and R5 each independently represents a substituent,
n represents an integer of 0 to 2,
L1 and L2 each independently represent a single bond or a divalent linking group)
The λ / 4 retardation film is an organic EL display device that satisfies the following formula (2), where Ro is a retardation value in an in-plane direction with respect to light having a wavelength of 550 nm, and Rth is a retardation value in a thickness direction.
Formula (2) 100 ≦ Ro ≦ 170 nm
0 ≦ Rth ≦ 300nm   The organic EL display device according to claim 1, wherein the compound (A) is a liquid crystal phase in any temperature range of 100 ° C. to 300 ° C.   The organic EL display device according to claim 1, wherein a content of the compound (A) is 0.1 to 30% by mass with respect to the cellulose ester.   The organic EL display device according to claim 1, wherein a haze of the λ / 4 retardation film is 0.5% or less. The organic according to claim 1 or 2, wherein a surface on the viewing side of the polarizer is in contact with the protective film, and a surface on the light emitting element side of the polarizer is in contact with the λ / 4 retardation film. EL display device.

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