JP2013097873A - Organic electroluminescent display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent display device capable of displaying a black color in which a background is not reflected even under external light or high-temperature high humidity environment, and furthermore to provide an organic electroluminescent display device in which the hue is hard to be changed when viewed obliquely.SOLUTION: An organic electroluminescent display device includes a circular polarization plate in which at least a light reflective electrode, a light-emitting layer, a transparent electrode, a λ/4 phase difference film and a linear polarization film are laminated in this order. The λ/4 phase difference film is composed of a single layer, contains cellulose acylate having the specified degree of substitution of an acyl group depending on a specific acyl group, and also contains an oligomer whose inherent birefringence value is negative.

Description

  The present invention relates to an organic electroluminescence display device, and more particularly to a liquid crystal display device including a circularly polarizing plate using a λ / 4 retardation film.

  In recent years, needs for organic electroluminescence display devices (hereinafter, also referred to as organic EL display devices) having surface light emitting elements are increasing in terms of low power consumption, low volume, and light weight.

  In an organic EL display device, a metal electrode having high reflectivity is usually used as a back electrode, and by using this metal electrode having high reflectivity, light emission luminance from the light emitting layer can be improved. However, since the metal electrode has high reflectivity, there is a problem that an external background is reflected and image display characteristics are deteriorated. That is, there is a problem that the interior lighting is intensely reflected and black color cannot be expressed in a bright place. In order to solve this problem, conventionally, in an organic EL display device, an antireflection film using a low refractive index layer is usually used, but a stronger antireflection means has been desired. Patent Document 1 discloses that a circularly polarizing element made of a λ / 4 retardation film is used to prevent reflection of external light on the mirror surface. The λ / 4 retardation film has a function of converting linearly polarized light having a specific wavelength into circularly polarized light.

  In the organic EL display device, in order to cut the reflection of the external light by the metal electrode in the entire wavelength region of visible light using the λ / 4 retardation film, the λ / 4 retardation film is applied in the entire visible wavelength region. It is necessary to set to λ / 4 phase difference (that is, a phase difference value that is ¼ of the optical wavelength (λ)). Therefore, the longer the optical wavelength (λ) is, the larger the retardation value of the film is required (in the present invention, the longer the optical wavelength is, the larger the retardation value is. The characteristic is called reverse wavelength dispersion.)

  A λ / 4 phase difference is achieved at a certain wavelength, for example, 550 nm, but a λ / 4 phase difference film having a phase difference value away from the λ / 4 phase difference is mounted on the organic EL display device at another wavelength. In this case (that is, when the reverse wavelength dispersion of the retardation of the λ / 4 retardation film is insufficient), reflection of light can be prevented with respect to green light, but red light or blue light can be prevented. There is a problem that it becomes difficult to completely prevent reflection, and the black display in a bright place becomes red or blue.

  However, in general, when a λ / 4 retardation film is produced, even if a λ / 4 retardation can be achieved at a certain wavelength, a reverse wavelength dispersion of ¼ wavelength over the entire visible light wavelength range should be achieved. Is difficult and has been studied in various ways. Further, as a result of studies by the present inventors, it is easy to make a trade-off relationship between improving the wavelength dispersibility of the λ / 4 retardation film and developing the retardation. It has been found that when the dispersibility is adjusted so as to be close to the ideal, the expression of the phase difference is reduced, so that the film thickness is increased.

  In Patent Document 2, in order to improve the wavelength dispersion of the retardation, a copolymer of a chain part having a positive uniaxial characteristic birefringence value and a chain part having a negative uniaxial characteristic birefringence value is used. A λ / 4 retardation film containing a resin has been proposed. However, the synthesis of this resin is time-consuming and expensive, and it has been difficult to overcome the trade-off between the improvement of the wavelength dispersion of the retardation and the development of the retardation even by this method.

  On the other hand, Patent Document 3 proposes a λ / 4 retardation film in which a film containing a material having a positive intrinsic birefringence value and a film containing a material having a negative intrinsic birefringence value are laminated. However, there is a problem that the film becomes thick when laminated, and when this film is mounted on an organic EL display device, hue variation is likely to occur when the display device is viewed from an oblique direction because the film is thick. There was a problem.

  Patent Document 4 proposes a λ / 4 retardation film composed of a film obtained by mixing a polymer having a positive intrinsic birefringence value such as norbornene resin and a polymer having a negative intrinsic birefringence value such as polystyrene. Yes. However, because the polymers are mixed together, the brittleness is poor and it is difficult to handle from the viewpoint of productivity, and the durability is poor. When used in a high temperature or high humidity environment, the film tends to whiten, and the visibility There was a problem that decreased.

  On the other hand, cellulose acylate is a resin often used as a protective film for a polarizing plate, and a stretched film of cellulose acylate has a characteristic of exhibiting reverse wavelength dispersion. In addition, since the photoelastic coefficient is smaller than that of polycarbonate, cyclic olefin resin, or the like, there is an advantage that unevenness in retardation can be reduced when stress is applied.

  However, the reverse wavelength dispersibility of the cellulose acylate was not reduced to ¼ wavelength over the entire visible light wavelength range, and improvement was required.

  Patent Document 5 discloses a technique for providing a retardation film having reverse wavelength dispersion in a wide band by incorporating a specific additive into cellulose acylate. However, even in this technique, since the compatibility between the cellulose acylate and the additive is not sufficient, there is a problem that the additive bleeds out in use in a high-temperature and high-humidity environment, and further, there is a problem that the brittleness is inferior.

Japanese Patent Laid-Open No. 8-322138 JP 2002-231438 A JP 2002-75659 A JP 2001-337222 A JP 2010-163482 A

  The present invention has been made in view of the above-described problems and problems, and its solution is to provide an organic electroluminescence display device capable of displaying black without reflection of a background portion even under external light or in a high temperature and high humidity environment. Furthermore, the present invention is to provide an organic electroluminescence display device in which hue variation hardly occurs when viewed from an oblique direction.

  In order to solve the above-mentioned problem, the present inventor, in the process of studying the above-mentioned problem, by incorporating an oligomer having a negative intrinsic birefringence value into cellulose acylate, while maintaining sufficient retardation, a wide band The present inventors have found that a λ / 4 retardation film having reverse wavelength dispersion in the wavelength region can be produced.

That is, the said subject which concerns on this invention is solved by the following means.
1. An organic electroluminescence display device comprising at least a light reflecting electrode, a light emitting layer, a transparent electrode, a circularly polarizing plate having a λ / 4 retardation film and a linearly polarizing film,
The λ / 4 retardation film is composed of a single layer, contains cellulose acylate satisfying the following formulas (1) and (2), has a weight average molecular weight in the range of 1500 to 80000, and is intrinsic An organic electroluminescence display device comprising an oligomer having a negative birefringence value.
Formula (1): 2.0 ≦ Z1 <3.0
Formula (2): 0.5 ≦ X
(In formulas (1) and (2), Z1 represents the total acyl group substitution degree of cellulose acylate, and X represents the sum of propionyl group substitution degree and butyryl group substitution degree of cellulose acylate.)
2. The ratio of the in-plane retardation value Ro (550) of light having a wavelength of 550 nm to the in-plane retardation value Ro (650) of light having a wavelength of 650 nm of the λ / 4 retardation film (Ro (550) / Ro ( 650)) is within a range of 0.83 to 0.97. 2. The organic electroluminescence display device according to item 1, wherein
3. The organic electroluminescence display device according to item 1 or 2, wherein the oligomer having a negative intrinsic birefringence value includes a styrene derivative structure.
4). The organic electroluminescence display device according to any one of claims 1 to 3, wherein the total degree of substitution Z1 of the cellulose acylate satisfies the following formula (3).
Formula (3): 2.0 ≦ Z1 <2.5
5. The content of the oligomer having a negative intrinsic birefringence value is in the range of 5 to 20% by mass with respect to the cellulose acylate, according to any one of items 1 to 4 The organic electroluminescence display device described.
6). The organic electroluminescence display device according to any one of claims 1 to 5, wherein the oligomer having a negative intrinsic birefringence value has a weight average molecular weight in the range of 1500 to 30000.

  The present invention can provide an organic electroluminescence display device capable of displaying black without reflection of a background portion under external light or in a high temperature and high humidity environment. Furthermore, it is possible to provide an organic electroluminescence display device in which hue variation hardly occurs when viewed obliquely.

(Mechanism of expression of the effect of the present invention)
The expression mechanism or action mechanism of the effect of the present invention is considered as follows. In other words, in the configuration of the present invention, by containing an oligomer having a negative intrinsic birefringence value in cellulose acylate, it is possible to control the wavelength dispersion of the retardation without deteriorating the retardation. In other words, it is considered that a λ / 4 retardation film having a retardation characteristic in which Ro (λ) / λ is approximately ¼ with respect to incident light in the entire visible light region could be produced. In the present invention, the λ / 4 retardation film is used for a circularly polarizing plate of an organic electroluminescence display device.

It is a cross-sectional schematic diagram of an example of the organic EL display device of the present invention. It is a schematic diagram for demonstrating the function of the circularly-polarizing plate which concerns on this invention.

The organic electroluminescence display device of the present invention is an organic electroluminescence display device provided with a circularly polarizing plate having at least a light reflecting electrode, a light emitting layer, a transparent electrode, a λ / 4 retardation film and a linear polarizing film. There,
The λ / 4 retardation film is composed of a single layer, contains cellulose acylate satisfying the following formulas (1) and (2), has a weight average molecular weight in the range of 1500 to 80000, and is intrinsic It contains an oligomer having a negative birefringence value.
Formula (1): 2.0 ≦ Z1 <3.0
Formula (2): 0.5 ≦ X
(In formulas (1) and (2), Z1 represents the total acyl group substitution degree of cellulose acylate, and X represents the sum of propionyl group substitution degree and butyryl group substitution degree of cellulose acylate.)
This feature is a technical feature common to the inventions according to claims 1 to 6.

  As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the in-plane retardation value by the light of wavelength 550 nm with respect to the in-plane retardation value Ro (650) by the light of wavelength 650 nm of the λ / 4 retardation film. The effect that the red reproducibility of the organic EL display device is good when the value of the ratio of Ro (550) (Ro (550) / Ro (650)) is within the range of 0.83 to 0.97. Is preferable.

  Furthermore, in the present invention, it is preferable that the oligomer having a negative intrinsic birefringence value includes a styrene derivative structure because an effect of reverse wavelength dispersion of retardation is obtained.

Furthermore, in this invention, it is preferable that the total acyl group substitution degree Z1 of the said cellulose acylate satisfy | fills following formula (3) from the effect of improving retardation expression.
Formula (3): 2.0 ≦ Z1 <2.5
Furthermore, in the present invention, the effect of improving the wavelength dispersion of the retardation is obtained when the content of the oligomer having a negative intrinsic refraction value is in the range of 5 to 20% by mass with respect to the cellulose acylate. This is preferable.

  Furthermore, in the present invention, the oligomer having a negative intrinsic birefringence value having a weight average molecular weight in the range of 1,500 to 30,000 has good compatibility with cellulose acylate and has a phase difference. It is preferable because an improvement effect of wavelength dispersion is obtained.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used by the meaning which includes the numbers described before and behind as a lower limit and an upper limit.

<Organic electroluminescence display device>
First, the organic EL display device of the present invention will be described below.

FIG. 1 is a schematic cross-sectional view showing the basic configuration of the organic EL display device of the present invention. The organic EL display device shown in FIG. 1, the light reflective electrode (Er), emitting layer _(O L), a transparent electrode (Et), the transparent substrate (Ts), λ / 4 retardation film (P λ _{/ 4)} and linear The polarizing film (P _L ) has a structure laminated in this order. The λ / 4 retardation film (P _{λ / 4} ) and the linearly polarizing film (P _L ) constitute a circularly polarizing plate.

Next, the antireflection function and the display function in the organic EL display device of the present invention will be described with reference to FIG. FIG. 2 schematically shows only the circularly polarizing plate in the organic EL display device shown in FIG. 1, and other members are omitted. The circularly polarizing plate shown in FIG. 2 includes a linearly polarizing film (P _L ) and a λ / 4 retardation film (P _{λ / 4} ). The circularly polarizing plate is disposed on the light emission side from the light emitting layer (not shown), the linearly polarizing film (P _L ) side (upper side) is outside the organic EL display device, and the λ / 4 retardation film (P _{The λ / 4} ) side is disposed inside the organic EL display device.

The organic EL display device, when light from the outside (including 1x and ly) is incident only linearly polarized light component that matches the polarization axis of the linear polarizing film _{(P L)} (ly) linear polarizing film _{(P L)} pass. The other component (lx) is absorbed by the linearly polarizing film (P _L ). The linearly polarized light (2y) that has passed through the linearly polarizing film (P _L ) is converted to circularly polarized light (2z) by passing through the λ / 4 retardation film (P _{λ / 4} ). When circularly polarized light (2z) is reflected by a light reflecting electrode (not shown) of the organic EL display device, it becomes reversely polarized light (3z). The reverse circularly polarized light (3z) passes through the λ / 4 retardation film (P _{λ / 4} ), and thus linearly polarized light (3y) in a direction different from the polarization axis direction of the linearly polarizing film (P _L ) by 90 °. Is converted to This linearly polarized light (3y) is absorbed without passing through the linearly polarizing film (P _L ). In this way, all light (lx and ly) incident on the organic EL display device from the outside is absorbed by the linearly polarizing film (P _L ), and reflection is prevented. Accordingly, it is possible to prevent the image display characteristics from being deteriorated due to the reflection of the background portion.

Light from the inside of the organic EL display device, that is, light emission from a light emitting layer (not shown) includes two kinds of circularly polarized light components (3z and 4z). One circularly polarized light (3z) passes through the λ / 4 retardation film (P _{λ / 4} ) as described above, and thus a straight line having a direction different from the polarization axis direction of the linearly polarizing film (P _L ) by 90 °. Converted to polarized light (3y). Then, the linearly polarized light (3y) is absorbed into the linear polarizing film _{(P L)} can not pass through the linear polarizing film _{(P L).} The other circularly polarized light (4z) passes through the λ / 4 retardation film (P _{λ / 4} ) and is converted to linearly polarized light (4y) that matches the polarization axis direction of the linearly polarizing film (P _L ). The linearly polarized light (4y) passes through the linearly polarizing film (P _L ) (4x) and is recognized as an image.

Note that linearly polarized light (3y) between the linearly polarizing film (P _L ) and the λ / 4 retardation film (P _{λ / 4} ) in a direction different from the polarization axis direction of the linearly polarizing film (P _L ) by 90 °. If a reflective polarizing plate having a function of reflecting the light is provided, the linearly polarized light (3y) is reflected without being absorbed and re-reflected by the reflective electrode, thereby matching the polarization axis direction of the linearly polarizing film (P _L ). Can be converted into linearly polarized light (4y). That is, by using the reflective polarizing plate, all of the light emitted by the light emitting layer (3z and 4z) can be emitted to the outside.

A polarizing plate protective film or another λ / 4 retardation film is disposed on the surface of the linear polarizing film (P _L ) opposite to the λ / 4 retardation film (P _{λ / 4} ) (see FIG. Not shown). When a protective film for polarizing plate or another λ / 4 retardation film is disposed on the outermost surface of the organic EL display device, the protective film for polarizing plate or another λ / 4 retardation film A transparent hard coat layer, an antiglare layer, an antireflection layer, and the like may be provided on the outermost surface of the film.

(Explanation of λ / 4 retardation film)
Here, the “λ / 4 retardation film” according to the present invention is one having an in-plane retardation value Ro of about ¼ for a predetermined wavelength of light (usually in the visible light region). Say.

<Oligomer whose intrinsic birefringence value is negative>
The organic EL display device of the present invention is an organic electroluminescence display device including at least a light reflection electrode, a light emitting layer, a transparent electrode, a circularly polarizing plate having a λ / 4 retardation film and a linear polarizing film. And
The λ / 4 retardation film is composed of a single layer, contains cellulose acylate satisfying the following formulas (1) and (2), has a weight average molecular weight in the range of 1500 to 80000, and is intrinsic It is characterized by containing an oligomer having a negative birefringence value.
Formula (1): 2.0 ≦ Z1 <3.0
Formula (2): 0.5 ≦ X
(In the formula, Z1 represents the total acyl group substitution degree of cellulose acylate, and X represents the sum of the propionyl group substitution degree and butyryl group substitution degree of cellulose acylate.)
In the present invention, an oligomer having a negative intrinsic birefringence value refers to a material having a characteristic of exhibiting optically negative uniaxiality when molecules are oriented with uniaxiality. For example, when an oligomer having a negative intrinsic birefringence value is contained in a resin, when light is incident on a layer formed with molecules having a uniaxial orientation, the refractive index of the light in the orientation direction is An oligomer that is smaller than the refractive index of light in a direction orthogonal to the orientation direction.

  In the present invention, “oligomer” refers to a polymer in which a relatively small number of monomers (for example, 200 or less monomers) are bonded. In the present invention, the weight average molecular weight of the oligomer is from 1500 to 80000, more preferably from 1500 to 30000, from the viewpoint of manifesting the effects of the present invention. When the weight average molecular weight is smaller than 1500, the film thickness for achieving the desired wavelength dispersion and the desired in-plane retardation value Ro (550) becomes thick, and the organic EL display device is obliquely viewed from the diagonal. It is not preferable because the hue fluctuation when viewed is likely to occur. Furthermore, when it is used for a long period of time or under severe conditions of temperature and humidity, oligomers are likely to precipitate in the film, and the black luminance when the display device is viewed from the front is deteriorated. Absent. In addition, if the oligomer has a weight average molecular weight exceeding 80000, the haze is likely to increase from the viewpoint of compatibility. Therefore, the black luminance when the display device is used and the luminance in the light emitting state of the EL element are deteriorated. This is not preferable because it is easy to break and from the viewpoint of production of the λ / 4 retardation film. In the present invention, if the weight average molecular weight of the oligomer is within the above range, the compatibility with the cellulose acylate is good, which is more preferable from the viewpoint of the effect of the present invention.

  Examples of the oligomer having a negative intrinsic birefringence value include oligomers having a styrene derivative structure, oligomers having a maleimide derivative structure, acrylonitrile oligomers, and polymethyl methacrylate oligomers. The oligomer containing a styrene derivative structure is preferably an oligomer containing a styrene derivative as a repeating unit.

(Oligomer containing styrene derivative structure)
The oligomer containing a styrene derivative structure used in the present invention can be roughly classified into styrene or a homopolymerized oligomer of a styrene derivative; styrene or a copolymerized oligomer of a styrene derivative and another monomer; and a mixture of these oligomers. . Examples of homopolymerized oligomers of styrene or derivatives thereof include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, o-nitrostyrene, p-aminostyrene, p-carboxylstyrene. And homopolymerized oligomers of p-phenylstyrene and 2,5-dichlorostyrene.

  Examples of copolymer oligomers of styrene or styrene derivatives and other monomers include styrene / acrylonitrile copolymer oligomers, styrene / methacrylonitrile copolymer oligomers, styrene / methyl methacrylate copolymer oligomers, and styrene / ethyl methacrylate copolymer copolymers. Oligomer, styrene / α-chloroacrylonitrile copolymer oligomer, styrene / methyl acrylate copolymer oligomer, styrene / ethyl acrylate copolymer oligomer, styrene / butyl acrylate copolymer oligomer, styrene / acrylic acid copolymer oligomer, styrene / methacrylic acid Acid copolymer oligomer, styrene / butadiene copolymer oligomer, styrene / isoprene copolymer oligomer, styrene / maleic anhydride copolymer oligomer, styrene / itaconic acid copolymer Oligomer, styrene / vinyl carbazole copolymer oligomer, styrene / N-phenylacrylamide copolymer oligomer, styrene / vinyl pyridine copolymer oligomer, styrene / vinyl naphthalene copolymer oligomer, α-methylstyrene / acrylonitrile copolymer oligomer, α-methylstyrene / Methacrylonitrile copolymer oligomer, α-methylstyrene / vinyl acetate copolymer oligomer, styrene / α-methylstyrene / acrylonitrile copolymer oligomer, styrene / α-methylstyrene / methyl methacrylate copolymer oligomer, styrene / styrene derivative copolymer Mention may be made of oligomers, styrene / acryloylmorpholine copolymer oligomers, and α-methylstyrene / acryloylmorpholine copolymer oligomers.

  Among these oligomers, a copolymer oligomer of styrene, α-methylstyrene and acryloylmorpholine is particularly preferable from the viewpoint of compatibility.

  The oligomer containing a maleimide derivative structure is preferably an oligomer containing a maleimide derivative as a repeating unit.

  These may be used alone or in combination of two or more.

  In this invention, it is preferable that content of the oligomer whose intrinsic birefringence value is negative exists in the range of 5-20 mass% with respect to the mass of a cellulose acylate. The content of 5% by mass or more is preferable because the effect of the present invention, in particular, the improvement effect of wavelength dispersion is excellent. Moreover, it is preferable that the content is 20% by mass or less because black luminance when viewed from the front does not deteriorate even if the product is used for a long time or under severe conditions of temperature and humidity.

  In a film in which a polymer having a positive intrinsic birefringence value and a polymer having a negative intrinsic birefringence value are mixed, the wavelength dispersion of retardation can be controlled by adjusting the blending ratio, stretching conditions, etc. When their molecular orientations become equal due to, for example, their slow axes are orthogonal, the resulting phase difference becomes the phase difference value as a result of canceling out the characteristics of each. In other words, when a polymer having a positive intrinsic birefringence value and a negative polymer are mixed, it is common for the retardation of the film to be reduced compared to the case of only a polymer having a positive intrinsic birefringence value. Met.

  However, according to the configuration of the present invention, that is, by making a material having a negative intrinsic birefringence value an oligomer instead of a polymer, the phase difference is deteriorated even when mixed with cellulose acylate having a positive intrinsic birefringence. Without lagging, it is possible to control the wavelength dispersion of the phase difference, and λ / 4 having a phase difference characteristic that Ro (λ) / λ is approximately ¼ for incident light in the entire visible light range. It is possible to produce a retardation film.

<In-plane phase difference Ro>
In the λ / 4 retardation film according to the present invention, the in-plane retardation Ro (550) measured at a wavelength of 550 nm is in the range of 110 to 170 nm, and Ro (550) is preferably 120 to 160 nm. More preferably, (550) is 130 to 150 nm.

The in-plane phase difference Ro is defined by the following equation.
Formula: Ro = (nx−ny) × d
In the formula, nx and ny are the refractive index nx (also referred to as the maximum refractive index in the plane of the film and the refractive index in the slow axis direction) at 23 ° C./55% RH, 450 nm, 550 nm or 650 nm, ny (film). The refractive index in the direction perpendicular to the slow axis in the plane), and d is the thickness of the film.

(Measurement method of in-plane phase difference Ro)
The in-plane retardation value Ro (λ) of the film at the wavelength (λ) and the retardation value Rt (λ) in the thickness direction represented by the following formula can be measured using a commercially available automatic birefringence meter. it can. Examples of the automatic birefringence meter include AxoScan manufactured by Axometric, and KOBRA-21ADH manufactured by Oji Scientific Instruments Co., Ltd., but in the present invention, each environment is used under an environment of 23 ° C. and 55% RH using AxoScan. Ro (λ) and Rt (λ) are calculated by measuring the birefringence at the wavelength.
Formula: Rt = {(nx + ny) / 2−nz} × d
In the formula, nx and ny are the refractive index nx (also referred to as the maximum refractive index in the plane of the film and the refractive index in the slow axis direction) at 23 ° C./55% RH, 450 nm, 550 nm or 650 nm, ny (film). The refractive index in the direction perpendicular to the slow axis in the plane) and nz (refractive index in the thickness direction of the film), and d is the thickness of the film.

<Chromatic dispersion of in-plane retardation Ro>
The λ / 4 retardation film according to the present invention has an in-plane retardation which is 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. A film is preferred.

(Ro (550) / Ro (650))
“In-plane phase difference of approximately ¼ in the wavelength range of visible light” means that the in-plane retardation value increases as the wavelength increases in the visible light region (for example, wavelength 400 to 700 nm). The ratio value Ro (550) / Ro (650) of the phase difference value Ro (550) and the in-plane phase difference value Ro (650) measured at a wavelength of 650 nm is 0.83 or more and 0.97 or less. It is preferable for red reproduction, more preferably 0.84 to 0.95, and particularly preferably 0.84 to 0.93.

(Ro (450) / Ro (550))
Further, a ratio value Ro (450) / Ro (550) of Ro (450), which is an in-plane retardation value measured at a wavelength of 450 nm, and Ro (550), which is an in-plane retardation value measured at a wavelength of 550 nm, 0.72 to 0.96 is preferable for blue reproduction, 0.76 to 0.94 is more preferable, and 0.79 to 0.89 is particularly preferable.

  In the present invention, Ro (450) / Ro (550) and Ro (550) / Ro (650) are controlled within the above preferred range by containing an oligomer having a negative intrinsic birefringence value in cellulose acylate. be able to.

<Film thickness>
The film thickness of the λ / 4 retardation film according to the present invention is not particularly limited, but 10 to 250 μm is used. More preferably, it is 10-100 micrometers. More preferably, it is 30-60 micrometers. When the film thickness is in a preferred range, the λ / 4 retardation film according to the present invention is mounted on an organic EL display device, and when black display is performed, it is preferable because the hue does not easily change when viewed obliquely. .

<Elongation at break>
The λ / 4 retardation film according to the present invention measures the breaking stress (MPa) in the direction of the slow axis of the film and the direction perpendicular thereto in the measurement based on JIS K7127-1999. The film thickness multiplied by the film thickness was calculated as the breaking elongation (N). In the present invention, the at least one breaking elongation is preferably 10% or more, more preferably 20% or more, and further preferably 30% or more. If the elongation at break is outside the above range, problems such as breakage tend to occur during the production of the λ / 4 retardation film, which is not preferable. In general, in a film prepared by mixing polymers having poor compatibility, the elongation at break tends to be low.

<Cellulose acylate>
Examples of the cellulose acylate used in the λ / 4 retardation film according to the present invention include esters of cellulose and an aliphatic carboxylic acid and / or aromatic carboxylic acid having about 2 to 22 carbon atoms. And an ester of a lower fatty acid having 6 or less carbon atoms.

  The acyl group bonded to the hydroxyl group of cellulose may be linear or branched, and may form a ring. Furthermore, another substituent may be substituted. In the case of the same degree of substitution, birefringence decreases when the number of carbon atoms described above is large. Therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose acylate preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  Specifically, cellulose acylate includes propionate group, butyrate group or phthalyl group in addition to acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate or cellulose acetate phthalate. Bound cellulose mixed fatty acid esters can be used. The butyryl group forming butyrate may be linear or branched.

  In the present invention, cellulose acetate, cellulose acetate butyrate, or cellulose acetate propionate is particularly preferably used as the cellulose acylate.

As the cellulose acylate used in the λ / 4 retardation film according to the present invention, those satisfying the following formulas (1) and (2) are used. That is, the three hydroxy groups of cellulose are each substituted with an acyl group such as an acetyl group, a propionyl group, and a butyryl group, and the total acyl group substitution degree Z1 of the cellulose acylate and the propionyl group substitution degree of the cellulose acylate And the total X of the degree of butyryl group substitution satisfy the following formulas (1) and (2).
Formula (1): 2.0 ≦ Z1 <3.0
Formula (2): 0.5 ≦ X
However, Z1: Total acyl group substitution degree of cellulose acylate X: Total sum of propionyl group substitution degree and butyryl group substitution degree of cellulose acylate.

(Description of degree of substitution)
The total acyl group substitution degree of the cellulose acylate used in the present invention will be described below.

  Cellulose is a resin in which β-glucose is linearly polymerized with glycosidic bonds, and the glucose unit, which is a structural unit, has hydroxy groups at the 2nd, 3rd and 6th positions. The cellulose acylate according to the present invention is a polymer obtained by esterifying a part of these hydroxy groups with an acyl group.

  The total acyl group substitution degree Z1 represents the total of the ratios of esterification of the 2-position, 3-position and 6-position hydroxy groups of the glucose unit which is a repeating unit. Specifically, the degree of substitution is 1 when each of the hydroxyl groups at the 2nd, 3rd and 6th positions of glucose is 100% esterified. Therefore, when all the 2nd, 3rd and 6th positions of glucose constituting cellulose are 100% esterified, the total degree of substitution is 3 at the maximum.

  Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group, and among these, the ratio of substitution with a propionyl group and a butyryl group is represented by a substitution degree X. The portion not substituted with an acyl group is usually present as a hydroxy group. In the present invention, the total substitution degree of the acyl group in the glucose unit constituting the cellulose acylate is represented by Z1.

  In the present invention, the sum X of the propionyl group substitution degree and the butyryl group substitution degree means a ratio of substitution with a propionyl group and a butyryl group among the three hydroxy groups in the glucose unit.

In the present invention, Z1 preferably satisfies the following formula (3).
Formula (3): 2.0 ≦ Z1 <2.5
If it is the said range, since the expression property of retardation will improve and the film thickness of (lambda) / 4 retardation film can be made thin, it is preferable. If the total acyl group substitution degree is less than 2, the solubility is not sufficient and the film-forming property is inferior.

  If the sum X of propionyl group substitution degree and butyryl group substitution degree X is less than 0.5, the water resistance of the λ / 4 retardation film deteriorates, and the fluctuation of the retardation occurs when the organic EL display device is used under high humidity conditions. Occurs, and the black brightness of the front under the external light increases, which is not preferable.

  That is, when the total acyl group substitution degree Z1, the propionyl group substitution degree, and the sum X of the butyryl group substitution degree are within the above ranges, the film forming property and the phase difference are excellent, and the phase difference is exhibited even in a high humidity environment. A film that hardly fluctuates can be obtained.

  The acyl group substitution degree is determined by the method prescribed in ASTM-D817-96.

  The cellulose acylate used in the present invention can be synthesized by a known method. Specifically, it can be synthesized with reference to methods described in JP-A-10-45804, JP-A-2009-161701, JP-A-2003-270442, and the like.

  Cellulose as a raw material of cellulose acylate is not particularly limited, and examples thereof include cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf and the like.

  Generally, cellulose is esterified by mixing cellulose as a raw material, a predetermined organic acid (such as acetic acid or propionic acid), an acid anhydride (such as acetic anhydride or propionic anhydride), and a catalyst (such as sulfuric acid). The reaction proceeds until the triester is formed. In the triester, the three hydroxy groups of the glucose unit are substituted with an acyl group of an organic acid. When two or more kinds of organic acids are used at the same time, a mixed ester type cellulose acylate such as cellulose acetate propionate or cellulose acetate butyrate can be produced. Next, cellulose acylate having a desired degree of acyl group substitution is synthesized by hydrolyzing the triester of cellulose. Thereafter, cellulose acylate can be obtained through steps such as filtration, precipitation, washing with water, dehydration, and drying.

  The mixed ester type cellulose acylate used in the present invention can be synthesized using an acid anhydride or acid chloride as an acylating agent. When the acylating agent is an acid anhydride, an organic acid (for example, acetic acid) or methylene chloride is used as a reaction solvent. As the catalyst, an acidic catalyst such as sulfuric acid is used. When the acylating agent is an acid chloride, a basic compound is used as a catalyst. In the most general synthetic method in the industry, cellulose acylate is obtained by esterifying cellulose with a mixed organic acid component containing an organic acid (acetic acid, propionic acid, butyric acid) corresponding to acetyl group and propionyl group or an acid anhydride thereof. Is synthesized.

  The amount of the acetylating agent, propionylating agent, and butyrylating agent used is adjusted so that the ester to be synthesized falls within the range of the substitution degree described above. The amount of the reaction solvent used is preferably 100 to 1000 parts by mass, more preferably 200 to 600 parts by mass with respect to 100 parts by mass of cellulose. It is preferable that the usage-amount of an acidic catalyst is 0.1-20 mass parts with respect to 100 mass parts of cellulose, More preferably, it is 0.4-10 mass parts.

  The reaction temperature is preferably 10 to 120 ° C, more preferably 20 to 80 ° C. Other acylating agents and esterifying agents (for example, sulfate esterifying agents) may be used in combination. Further, after completion of the acylation reaction, the degree of substitution may be adjusted by hydrolysis (saponification) as necessary. After completion of the reaction, the reaction mixture is separated using conventional means such as precipitation, washed and dried to obtain a mixed fatty acid ester of cellulose (for example, cellulose acetate propionate).

  As the cellulose acylate used in the present invention, either cellulose triacetate synthesized from cotton linter or cellulose triacetate synthesized from wood pulp can be used alone or in combination. It is preferable to use a large amount of cellulose acylate synthesized from a cotton linter that has good releasability from a belt or drum because of high production efficiency.

  The weight average molecular weight (Mw) of cellulose acylate is preferably 75,000 or more, and more preferably in the range of 75,000 to 240,000. The number average molecular weight (Mn) is preferably 60,000 to 300,000, and if the number average molecular weight is within this range, the mechanical strength of the resulting film is increased, which is preferable. More preferably, cellulose acylate having a number average molecular weight of 70,000 to 200,000 is used.

  The measuring method of the weight average molecular weight (Mw) and number average molecular weight (Mn) of a cellulose acylate can be based on the following method.

(Molecular weight measurement method)
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured using gel permeation chromatography. 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 Corp.) Mw = 100000 to 500 calibration curves were used. Thirteen samples are used at approximately equal intervals.

(Residual sulfuric acid content)
The residual sulfuric acid content in the cellulose acylate is preferably in the range of 0.1 to 45 mass ppm in terms of elemental sulfur. These are considered to be contained in the form of salts. If the residual sulfuric acid content exceeds 45 ppm by mass, there is a tendency to break during hot stretching or slitting after hot stretching. The residual sulfuric acid content is more preferably in the range of 1 to 30 mass ppm. The residual sulfuric acid content can be measured by a method prescribed in ASTM-D817-96.

(Free acid content)
Moreover, it is preferable that the free acid content in a cellulose acylate is 1-500 mass ppm. The above range is preferable because it is difficult to break as described above. In addition, it is preferable that free acid content is the range of 1-100 mass ppm, and also it becomes difficult to fracture | rupture. The range of 1-70 mass ppm is especially preferable. The free acid content can be measured by the method prescribed in ASTM-D817-96.

(Residue amount adjustment method)
By washing the synthesized cellulose acylate more sufficiently than when used in the solution casting method, the residual alkaline earth metal content, residual sulfuric acid content, and residual acid content are within the above ranges. And can be preferable.

(Bright spot foreign matter)
Moreover, it is preferable that a cellulose acylate has few bright spot foreign materials when it is made into a film. Bright spot foreign matter means that when two polarizing plates are placed in a crossed Nicol state, an optical film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. It means a point (foreign matter) where light from the opposite side appears to leak. The number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less, more preferably 100 / cm ² or less, and 50 / cm ² or less. Is more preferably 30 pieces / cm ² or less, particularly preferably 10 pieces / cm ² or less, and most preferably none.

Further, the bright spots having a diameter of 0.005 to 0.01 mm or less are also preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, and 50 pieces / cm ² or less. Is more preferably 30 pieces / cm ² or less, particularly preferably 10 pieces / cm ² or less, and most preferably none.

(Amount of metal contained)
Cellulose acylate is also affected by trace metal components in cellulose acylate. These trace metal components are thought to be related to the water used in the production process, but it is preferable that there are few components that can become insoluble nuclei, in particular, metal ions such as iron, calcium, magnesium, An insoluble matter may be formed by salt formation with a polymer degradation product or the like that may contain an organic acidic group, and it is preferable that the amount is small. In addition, the calcium (Ca) component easily forms a coordination compound (that is, a complex) with an acidic component such as a carboxylic acid or a sulfonic acid, and many ligands. Insoluble starch, turbidity) may be formed.

  Specifically, for the iron (Fe) component, the content in cellulose acylate is preferably 1 mass ppm or less. Moreover, about calcium (Ca) component, content in a cellulose acylate becomes like this. Preferably it is 60 mass ppm or less, More preferably, it is 0-30 mass ppm. Furthermore, regarding the magnesium (Mg) component, too much is also insoluble, so the content in the cellulose acylate is preferably 0 to 70 ppm by mass, and particularly preferably 0 to 20 ppm by mass. .

  It should be noted that the content of metal components such as the content of iron (Fe) component, the content of calcium (Ca) component, the content of magnesium (Mg) component, etc., is a micro digest wet cracking device ( After pretreatment with sulfuric acid decomposition (sulfuric acid decomposition) and alkali fusion, analysis can be performed using ICP-AES (inductively coupled plasma emission spectrometer).

<Additives>
Various additives may be added to the λ / 4 retardation film according to the present invention as necessary.

[Plasticizer]
In the λ / 4 retardation film according to the present invention, a plasticizer can be used in combination in order to improve the fluidity and flexibility of the composition. Examples of the plasticizer include phthalate ester, fatty acid ester, trimellitic ester, phosphate ester, polyester, and epoxy.

  Of these, polyester and phthalate plasticizers are preferably used. Polyester plasticizers are superior in non-migration and extraction resistance compared to phthalate ester plasticizers such as dioctyl phthalate, but are slightly inferior in plasticizing effect and compatibility.

  Therefore, it can be applied to a wide range of uses by selecting or using these plasticizers according to the use.

(Polyester plasticizer)
The polyester plasticizer is a reaction product of a monovalent or tetravalent carboxylic acid and a monovalent or hexavalent alcohol, and is mainly obtained by reacting a divalent carboxylic acid with a glycol. . Representative divalent carboxylic acids include glutaric acid, itaconic acid, adipic acid, phthalic acid, azelaic acid, sebacic acid and the like.

  In particular, when adipic acid, phthalic acid or the like is used, those having excellent plasticizing properties can be obtained. Examples of the glycol include glycols such as ethylene, propylene, 1,3-butylene, 1,4-butylene, 1,6-hexamethylene, neopentylene, diethylene, triethylene, and dipropylene. These divalent carboxylic acids and glycols may be used alone or in combination.

  The ester plasticizer may be any of ester, oligoester, and polyester types, and the molecular weight is preferably in the range of 100 to 10,000, and preferably in the range of 600 to 3000, which has a large plasticizing effect.

  The viscosity of the plasticizer has a correlation with the molecular structure and molecular weight. In the case of an adipic acid plasticizer, the viscosity is preferably in the range of 200 to 5000 MPa · s (25 ° C.) in view of compatibility and plasticization efficiency. Furthermore, some polyester plasticizers may be used in combination.

  The plasticizer is preferably added in an amount of 0.5 to 30 parts by mass with respect to 100 parts by mass of the film according to the present invention. If the added amount of the plasticizer exceeds 30 parts by mass, the surface becomes sticky, which is not preferable for practical use.

(Polyhydric ester plasticizer)
The polyhydric alcohol ester plasticizer is an ester compound of a polyhydric alcohol represented by the following general formula (1).

Formula (1): R1- (OH) n
(In the formula, R1 represents an n-valent organic group, and n represents a positive integer of 2 or more)
Preferred examples of the polyhydric alcohol include ethylene glycol, propylene glycol, trimethylolpropane, and pentaerythritol.

  As monocarboxylic acid used for polyhydric alcohol ester, well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. The aromatic monocarboxylic acid which has, or derivatives thereof can be mentioned. In particular, benzoic acid is preferred.

  The molecular weight of the polyhydric alcohol ester is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  In addition, trimethylolpropane triacetate, pentaerythritol tetraacetate and the like are also preferably used. It is also preferable to use the ester compound (A) represented by the general formula (I) described in JP-A-2008-88292.

(Polycarboxylic acid ester plasticizer)
The polyvalent carboxylic acid ester compound is composed of an ester of divalent or higher, preferably divalent to 20 valent polyvalent carboxylic acid and alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 2 to 20 valent.

The polyvalent carboxylic acid is represented by the following general formula (2).
General formula (2): R2 (COOH) m (OH) n
(Where R2 is an (m + n) -valent organic group, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group is a carboxy group, and an OH group is an alcoholic or phenolic hydroxy group)
Examples of preferable polyvalent carboxylic acids include the following. Divalent or higher polyvalent aromatic carboxylic acids or derivatives such as phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid Aliphatic polycarboxylic acids such as fumaric acid, maleic acid and tetrahydrophthalic acid, and oxypolycarboxylic acids such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used.

  Known alcohols and phenols can be used as the alcohol used in the polyvalent carboxylic acid ester compound that can be used in the present invention. For example, an aliphatic saturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used.

  It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. Further, cycloaliphatic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used. Examples of phenol include phenol, paracresol, dimethyl Phenol etc. can be used individually or in combination of 2 or more types.

  It is also preferable to use the ester compound (B) represented by the general formula (II) described in JP-A-2008-88292.

  Although there is no restriction | limiting in particular in the molecular weight of a polyhydric carboxylic acid ester compound, It is preferable that it is the range of molecular weight 300-1000, and it is more preferable that it is the range of 350-750.

  The alcohol used for the polyvalent carboxylic acid ester may be one kind or a mixture of two or more kinds.

  The acid value of the polyvalent carboxylic acid ester compound is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less.

  The acid value refers to the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxy group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

(Glycolate plasticizer)
The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used. Examples of the alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate and the like.

(Phthalate ester plasticizer)
Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

(Citrate ester plasticizer)
Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

(Fatty acid ester plasticizer)
Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

(Phosphate ester plasticizer)
Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

(Sugar ester compound plasticizer)
The λ / 4 retardation film according to the present invention has at least one furanose structure or pyranose structure as a plasticizer, and all or one of OH groups in the compound having 1 to 12 furanose structures or pyranose structures bonded thereto. The compound which esterified the part (it may be called a sugar ester compound) can be included.

  Examples of preferable “compounds having at least one furanose structure or pyranose structure and having 1 to 12 furanose structures or pyranose structures bonded to each other” include JP-A Nos. 62-42996 and 10-237084. It is described in.

  When included in the λ / 4 retardation film according to the present invention, it is preferably contained in an amount of 0 to 35% by mass, particularly 5 to 30% by mass with respect to the cellulose ester.

[Ultraviolet absorber]
The λ / 4 retardation film according to the present invention preferably contains an ultraviolet absorber, and examples of the ultraviolet absorber used include benzotriazole-based, 2-hydroxybenzophenone-based or salicylic acid phenyl ester-based ones. . 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.

  Here, among ultraviolet absorbers, ultraviolet absorbers having a molecular weight of 400 or more are less likely to volatilize at a high boiling point and are difficult to disperse even during high-temperature molding, so that the weather resistance is effectively improved with a relatively small amount of addition. be able to.

  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 Examples include hybrid systems having both structures, 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.

[Fine particles]
In the retardation film according to the present invention, fine particles may be added after the cellulose acylate solution treatment step, if necessary.

  Examples of the fine particles include inorganic compounds such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, and aluminum silicate. And magnesium silicate and calcium phosphate. Further, fine particles of an organic compound can also be preferably used. Examples of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, melamine resin Examples thereof include polyolefin-based powders, polyester-based resins, polyamide-based resins, polyimide-based resins, polyfluorinated ethylene-based resins, and pulverized and classified products of organic polymer compounds such as starch. Alternatively, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray drying method or a dispersion method, or an inorganic compound can be used.

  Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The average primary particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm.

  These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable.

  The content of these fine particles in the cellulose ester is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of the polymer include silicone resin, fluorine resin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.
Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the turbidity of the retardation film low. In the λ / 4 retardation film according to the present invention, the dynamic friction coefficient of at least one surface is preferably 0.2 to 1.0.

[Other additives]
Furthermore, various antioxidants can also be added to the λ / 4 retardation film according to the present invention in order to improve thermal decomposability and thermal colorability during molding. It is also possible to add an antistatic agent to give antistatic performance.

  For the λ / 4 retardation film according to 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 phosphate esters, halogen-containing condensed phosphonate esters, halogen-containing phosphite esters, 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.

  Furthermore, various antioxidants can also be added to the λ / 4 retardation film according to the present invention in order to improve thermal decomposability and thermal colorability during molding. It is also possible to add an antistatic agent to give antistatic performance.

  Various additives may be batch-added to a dope that is a resin-containing solution before film formation, or an additive solution may be separately prepared and added in-line. In particular, it is preferable to add a part or all of the fine particles in-line in order to reduce the load on the filter medium.

  When the additive solution is added in-line, it is preferable to dissolve a small amount of resin in order to improve mixing with the dope. A preferable amount of the resin is 1 to 10 parts by mass, and more preferably 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

  In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer) or the like is preferably used.

<Formation method of λ / 4 retardation film>
Next, an example of a method for producing a λ / 4 retardation film according to the present invention will be described, but the present invention is not limited thereto. As a method for forming a λ / 4 retardation film, a production method such as an inflation method, a T-die method, a calendar method, a cutting method, a solution casting method, a melt casting method, an emulsion method, or a hot press method can be used. .

  The λ / 4 retardation film according to the present invention may be formed by either a solution casting method or a melt casting method. The solution casting method is preferable from the viewpoints of suppressing coloring of the film, suppressing defects of foreign matters, and suppressing optical defects such as die lines.

Moreover, the method of producing by a melt casting method is preferable from the point of the residual suppression of the solvent used for melt | dissolution of cellulose acetate. Methods formed by melt casting can be classified into melt extrusion molding methods, press molding methods, inflation methods, injection molding methods, blow molding methods, stretch molding methods, and the like.
[Production of raw film]
1. Solution Casting Method The λ / 4 retardation film according to the present invention can be produced by a solution casting method. In the solution casting method, a step of preparing a dope by dissolving a resin and an additive in a solvent, a step of casting the dope on a belt-shaped or drum-shaped metal support, and a step of drying the cast dope as a web , Peeling from the metal support, stretching or maintaining the width, further drying, and winding the finished film.

  The concentration of cellulose acetate in the dope is preferably higher because the drying load after casting on the 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 preferred because the web can be dried faster, but if it is too high, the web may foam or the 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 warm 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 planarity, 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%.

The amount of residual solvent is defined by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Note that M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour. Further, in the drying step of the λ / 4 retardation film, the web is peeled off from the metal support, and further dried, so that the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less. And particularly preferably 0 to 0.01% by mass or less.

  In the film drying step, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

(Organic solvent)
The organic solvent useful for forming the dope when the retardation film according to the present invention is produced by the solution casting method can be used without limitation as long as it dissolves the cellulose ester resin and other additives simultaneously. it can.

  For example, as a chlorine organic solvent, methylene chloride, as a non-chlorine organic solvent, 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- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.

  In addition to the organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy, and when the proportion of alcohol is small, the acrylic resin and cellulose ester resin dissolve in a non-chlorine organic solvent system. There is also a role to promote.

  In particular, at least 15 to 45 mass% in total of two kinds of acrylic resin and cellulose ester resin was dissolved in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. A dope composition is preferred.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

2. Melt Film Formation Method The λ / 4 retardation film according to the present invention may be formed by a melt film formation method. The melt film forming method means that a composition containing an additive such as a resin and a plasticizer is heated and melted to a temperature showing fluidity, and then a melt containing fluid cellulose acetate is cast.

  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. A plurality of raw materials used for melt extrusion are usually preferably kneaded and pelletized in advance.

  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 into the extruder from the supply hopper, 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.

  In addition, the film obtained as described above may be subjected to a stretching treatment after passing through a step in contact with a 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.

3. Stretching method 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 peripheral speed difference 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, the λ / 4 retardation film according to the present invention is preferably stretched in a stretching process in a 45 ° direction with respect to the film conveying direction in order to set the orientation angle θ with respect to the film longitudinal direction to 35 to 55 °.
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.

<Circularly polarizing plate>
The circularly polarizing plate according to the present invention comprises at least a protective film for polarizing plate, a polarizer and a λ / 4 retardation film, and the absorption axis of the polarizer and the slow axis of the λ / 4 retardation film are substantially 45. Bonded with an inclination of °. When this circularly polarizing plate is used in an organic EL image display device, it is possible to shield the specular reflection of the metal electrode of the organic EL light emitter. When used in a display device capable of displaying a stereoscopic image, the λ / 4 retardation film according to the present invention is bonded in the order of λ / 4 retardation film, polarizer, and λ / 4 retardation film. It can also be set as a circularly polarizing plate.

  The protective film for polarizing plate bonded to the surface opposite to the surface on which the λ / 4 plate is bonded to the polarizer has retardation values Ro and Rt defined by the above formulas of 20 to 150 nm, respectively. It is preferable that the retardation film is 70 to 400 nm, or 0 nm ≦ Ro ≦ 2 nm and −15 nm ≦ Rt ≦ 15 nm. For example, as a commercially available cellulose ester film, Konica Minoltak KC8UX, KC4UX, KC5UX, KC4UY, KC8UY, KC4UA, KC6UA, KC8UCR3, KC8UCR4, KC8UCR5, KC4UE, KC8UE, KC4FR-4, KC4FR-4 4, KC4HR-1, KC8UY-HA, KC8UX-RHA (manufactured by Konica Minolta Opto Co., Ltd.) and the like are also preferably used.

  Moreover, in order to prevent deterioration due to ultraviolet rays in the organic EL display device of the present invention, the circularly polarizing plate according to the present invention preferably has an ultraviolet absorption function. It is preferable that the protective film on the viewing side has an ultraviolet absorption function because both the polarizer and the organic EL element can be protected from ultraviolet rays, but the λ / 4 wavelength plate on the light emitter side also has an ultraviolet absorption function. It is preferable because deterioration of the organic EL element can be further suppressed. Since the retardation film produced by the production method according to the present invention has not only a function as a λ / 4 retardation film but also a protective film property, the production cost of the polarizing plate can be reduced.

(Method for producing circularly polarizing plate)
The circularly polarizing plate can be produced by a general method for producing a normal polarizing plate. The λ / 4 retardation film according to the present invention is subjected to alkali saponification treatment, and is attached to at least one surface of a polarizer produced by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. It is preferable to match. It is preferable to saponify and paste the protective film for a polarizing plate on the other surface in the same manner.

  In the production of the λ / 4 retardation film according to the present invention, in the case of a λ / 4 retardation film produced by stretching in a direction substantially 45 ° with respect to the longitudinal direction, the absorption axis of the polarizing film is long. The polarizer is positioned in the direction, and the longitudinal direction of the polarizer and the slow axis of the λ / 4 retardation film are 20 ° or more and less than 70 °, more preferably 40 ° or more and less than 50 °, particularly preferably 44 ° or more. It can be continuously bonded by roll-to-roll so that it is less than 46 °.

  The circularly polarizing plate can be constituted by further bonding a protective film on one surface of the circularly polarizing plate and a separate film on the opposite surface. The protective film and the separate film are used for the purpose of protecting the circularly polarizing plate at the time of shipping the circularly polarizing plate and at the time of product inspection.

(Linear polarizing film)
In the present invention, the linearly polarizing film is combined with the λ / 4 retardation film and functions as a circularly polarizing plate. In the present invention, the linear polarizing film (polarizer) is an element that allows only light having a polarization plane in a certain direction to pass through. A typical linear polarizing film that is currently known includes an iodine-based polarizing film and a dichroic dye. The dye-based polarizing film and the polyene-based polarizing film to be used can be used. In general, the iodine polarizing film and the dye polarizing film can be produced by subjecting a polyvinyl alcohol film to a stretching treatment or the like. The polarization axis (transmission axis) of the polarizing film corresponds to the stretching direction of the film. As described above, when a reflective polarizing plate is provided between the λ / 4 retardation film and the linear polarizing film, more light emitted from the light emitting layer can be emitted to the outside. The reflective polarizing plate has a function of transmitting linearly polarized light that matches the polarization axis direction of the linearly polarizing film used together and reflecting linearly polarized light in a direction different from the polarization axis direction. Specifically, a birefringent light polarizer (described in Japanese Patent Application Laid-Open No. 8-503313) in which polymer thin films having different refractive indexes in one direction are alternately stacked, or a polarization separation film having a cholesteric structure (Japanese Patent Laid-Open No. 11-151). (Described in JP-A-44816) can be preferably used.

(Functional layer)
The outermost λ / 4 retardation film or the protective film for polarizing plate of the circularly polarizing plate according to the present invention includes a hard coat layer, an antistatic layer, a backcoat layer, an antireflection layer, and slipperiness as required. Functional layers such as a layer, an adhesive layer, an antiglare layer, and a barrier layer can be provided.

<Hard coat layer>
The hard coat layer used in the present invention contains an actinic radiation curable resin, and is a layer mainly composed of a resin that cures through a crosslinking reaction by irradiation with an actinic ray (also referred to as an active energy ray) such as an ultraviolet ray or an electron beam. Preferably there is.

  As the actinic radiation curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and the actinic radiation curable resin layer is cured by irradiation with actinic radiation such as ultraviolet rays or electron beams. It is formed.

  Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, but the resin that is cured by ultraviolet irradiation is excellent in mechanical film strength (abrasion resistance, pencil hardness). preferable.

  As the ultraviolet curable resin, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, or an ultraviolet curable epoxy resin is preferable. Used. Of these, ultraviolet curable acrylate resins are preferred.

  The hard coat layer preferably contains a photopolymerization initiator to accelerate the curing of the actinic radiation curable resin. The amount of the photopolymerization initiator is preferably contained in a mass ratio of photopolymerization initiator: active ray curable resin = 20: 100 to 0.01: 100.

  Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto.

The hard coat layer preferably contains fine particles of an inorganic compound or an organic compound.
As inorganic fine particles, silicon oxide, titanium oxide, aluminum oxide, tin oxide, indium oxide, ITO, zinc oxide, zirconium oxide, magnesium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated silicic acid Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate. In particular, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and the like are preferably used.

  As organic particles, polymethacrylic acid methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicone resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder, A polyolefin resin powder, a polyester resin powder, a polyamide resin powder, a polyimide resin powder, a polyfluoroethylene resin powder, or the like can be added.

  The average particle size of these fine particle powders is not particularly limited, but is preferably 0.01 to 5 μm, and more preferably 0.01 to 1.0 μm. Moreover, you may contain 2 or more types of microparticles | fine-particles from which a particle size differs. The average particle diameter of the fine particles can be measured by, for example, a laser diffraction particle size distribution measuring device.

  The ratio of the ultraviolet curable resin composition and the fine particles is desirably 10 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the resin composition.

  These hard coat layers are coated using a known method such as a gravure coater, dip coater, reverse coater, wire bar coater, die coater, ink jet method, and the like. And can be formed by UV curing.

  The dry thickness of the hard coat layer is an average film thickness of 0.1 to 30 μm, preferably 1 to 20 μm, particularly preferably 6 to 15 μm.

  As a light source for UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 200 mJ / cm ² .

<Back coat layer>
In the circularly polarizing plate according to the present invention, a backcoat layer may be provided on the surface of the film opposite to the side where the hardcoat layer is provided to prevent curling and sticking.

  As particles added to the back coat layer, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, tin oxide, and oxidation. Mention may be made of indium, zinc oxide, ITO, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate.

  The particles contained in the backcoat layer are preferably 0.1 to 50% by mass with respect to the binder. When the back coat layer is provided, the increase in haze is preferably 1.5% or less, more preferably 0.5% or less, and particularly preferably 0.1% or less.

  As the binder, cellulose esters such as diacetylcellulose are preferable.

<Antireflection layer>
In the circularly polarizing plate according to the present invention, an antireflection layer can be coated on the hard coat layer.

  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. 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.

  The low refractive index layer preferably contains silica-based fine particles, and the refractive index is lower than the refractive index of the cellulose film as the support, and is in the range of 1.30 to 1.45 when measured at 23 ° C. and a wavelength of 550 nm. It is preferable that

  The film thickness of the low refractive index layer is preferably 5 nm to 0.5 μm, more preferably 10 nm to 0.3 μm, and most preferably 30 nm to 0.2 μm.

  The composition for forming a low refractive index layer preferably contains at least one kind of particles having an outer shell layer and porous or hollow inside as silica-based fine particles. In particular, the particles having the outer shell layer and having a porous or hollow inside are preferably hollow silica-based fine particles.

  In addition, a silane coupling agent, a curing agent, a surfactant and the like may be added as necessary.

<Reflective electrode>
In the present invention, the reflective electrode is preferably formed using a metal material having a high light reflectance. Examples of the metal material include Mg, MgAg, MgIn, Al, and LiAl. It is preferable that the surface of the reflective electrode is flat because irregular reflection of light can be prevented. The reflective electrode may be patterned. The reflective electrode can be formed by sputtering or the like, and etching can be used for patterning.

<Light emitting layer>
In the present invention, the light emitting material contained in the light emitting layer is not particularly limited, and the light emitting material may be an inorganic material or an organic material. Among these, an organic EL display device using an organic material as a light emitting material is preferable. The light emitting layer can be formed by evaporating a light emitting material. The light emitting layer may be added with a function as a charge transport layer by containing a charge transport material, or may be added with a function as a hole transport layer by containing a hole transport material. In addition to the light emitting layer, a charge transport layer and / or a hole transport layer may be provided.

<Transparent electrode>
In the present invention, an ITO electrode is generally used as the transparent electrode. The transparent electrode may be patterned. The transparent electrode can be formed by sputtering or the like, and etching can be used for patterning. In addition, in the organic EL display device of the present invention, a transparent substrate can be provided between the transparent electrode and the circularly polarizing plate, if desired. As the transparent substrate, a glass substrate and a light transmissive plastic film can be used.

  In the organic EL display device of the present invention, the light emitting layer can emit light and can be displayed as an image by providing a current-carrying portion in the transparent electrode and the reflective electrode. In the organic EL display device of the present invention, the R (red) light-emitting layer, the G (green) light-emitting layer, and the B (blue) light-emitting layer are formed by patterning using a photomask or the like. By configuring the layers so that they can be individually energized, a display element for a full-color image can be obtained.

  In addition, the structure of the organic EL display device described in International Patent Application No. WO96 / 34514, Japanese Patent Application Laid-Open Nos. 9-127585 and 11-45058 can be applied to the organic EL display device of the present invention. In that case, it can replace with the said antireflection means with which the said organic EL display apparatus is equipped, or can be set as the structure which incorporated the said circularly-polarizing plate in combination. In addition, as the organic EL display device of the present invention, for example, a configuration in which the circularly polarizing plate is incorporated in an inorganic EL display described in “Electroluminescence display” (Toshio Higuchi, Sangyo Tosho Co., Ltd., published in 1991). It can also be.

＜固有複屈折値が負であるオリゴマーの合成＞
本発明に係る「固有複屈折値が負であるオリゴマー」について、以下のようにして合成した。 EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented. The cellulose acylate used is shown in Table 1.

<Synthesis of an oligomer having a negative intrinsic birefringence value>
The “oligomer having a negative intrinsic birefringence value” according to the present invention was synthesized as follows.

[Synthesis Example 1]
<Synthesis of Compound O1>
(Styrene / acryloylmorpholine = 40/60)
In the reactor, 1.0 part by mass of styrene, 2.0 parts by mass of acryloylmorpholine (ACMO), 10 parts by mass of toluene, and 0.1 part by mass of azobisisobutyronitrile were added and heated to 80 ° C. After completion of the polymerization, the reaction solution was put into a large amount of hexane, the copolymer was separated, and a compound O1 which was a copolymer oligomer was obtained through filtration, washing and drying steps. Compound O1 was confirmed to have a weight average molecular weight of 5,500 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O1 was a copolymer of styrene and acryloylmorpholine, and the composition was approximately styrene: acryloylmorpholine = 40: 60.

<Synthesis of Compound O2>
(Styrene / ACMO = 40/60)
In the reactor, 1.0 part by mass of styrene, 2.0 parts by mass of acryloylmorpholine, 10 parts by mass of toluene, and 0.05 part by mass of azobisisobutyronitrile were added and heated to 80 ° C. After completion of the polymerization, the reaction solution was poured into a large amount of hexane to separate the copolymer oligomer, and a compound O2 was obtained through filtration, washing and drying steps. This copolymer was confirmed to have a weight average molecular weight of 9000 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O2 was a copolymer of styrene and acryloylmorpholine, and the composition was approximately styrene: acryloylmorpholine = 40: 60.

<Synthesis of Compound O3>
(Styrene / ACMO = 40/60)
In the reactor, 1.0 part by mass of styrene, 2.0 parts by mass of acryloylmorpholine, 10 parts by mass of toluene, and 0.01 parts by mass of azobisisobutyronitrile were added and heated to 80 ° C. After completion of the polymerization, the reaction solution was put into a large amount of hexane, the copolymerized oligomer was separated, and a compound O3 was obtained through filtration, washing and drying steps. This copolymer was confirmed to have a weight average molecular weight of 28,000 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O3 was a copolymer of styrene and acryloylmorpholine, and the composition was approximately styrene: acryloylmorpholine = 40: 60.

<Synthesis of Compound O4>
(Styrene / ACMO = 70/30)
In the reactor, 1.0 part by mass of styrene, 2.0 parts by mass of acryloylmorpholine, 10 parts by mass of toluene, and 0.1 part by mass of azobisisobutyronitrile were added and heated to 80 ° C. After the completion of the polymerization, the reaction solution was put into a large amount of hexane to separate the copolymer oligomer, and a compound O4 was obtained through filtration, washing and drying steps. This copolymer oligomer was confirmed to have a weight average molecular weight of 5700 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O4 was a copolymer of styrene and acryloylmorpholine, and the composition was approximately styrene: acryloylmorpholine = 70: 30.

<Synthesis of Compound O5>
(N-phenylmaleimide / ACMO = 40/60)
In the reactor, 1.0 part by mass of N-phenylmaleimide, 2.0 parts by mass of acryloylmorpholine, 10 parts by mass of toluene, and 0.01 parts by mass of azobisisobutyronitrile were added and heated to 80 ° C. After completion of the polymerization, the reaction solution was put into a large amount of hexane to separate the copolymer oligomer, and a compound O5 was obtained through filtration, washing and drying steps. Compound O5 was confirmed to have a weight average molecular weight of 25000 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O5 was a copolymer of N-phenylmaleimide and acryloylmorpholine, and the composition was approximately N-phenylmaleimide: acryloylmorpholine = 40: 60.

<Synthesis of Compound O6>
(P-acetoxystyrene / ACMO = 30/70)
In the reactor, 0.6 parts by mass of p-acetoxystyrene, 1.0 part by mass of acryloylmorpholine, 10 parts by mass of toluene, and 0.05 parts by mass of azobisisobutyronitrile were added and heated to 80 ° C. After completion of the polymerization, the reaction solution was poured into a large amount of hexane to separate the copolymer oligomer, and a compound O6 was obtained through filtration, washing and drying steps. Compound O6 was confirmed to have a weight average molecular weight of 10,000 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O6 was a copolymer oligomer of p-acetoxystyrene and acryloylmorpholine, and the composition was approximately p-acetoxystyrene: acryloylmorpholine = 30: 70.

<Synthesis of Compound O7>
(Styrene / ACMO = 40/60)
In the reactor, 1.0 part by mass of styrene, 2.0 parts by mass of acryloylmorpholine, 10 parts by mass of toluene, and 0.005 part by mass of azobisisobutyronitrile were added and heated to 80 ° C. After completion of the polymerization, the reaction solution was put into a large amount of hexane, the copolymerized oligomer was separated, and a compound O7 was obtained through filtration, washing and drying steps. This copolymer was confirmed to have a weight average molecular weight of 50,000 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O7 was a copolymer of styrene and acryloylmorpholine, and the composition was approximately styrene: acryloylmorpholine = 40: 60.

<Synthesis of Compound O8>
(Styrene / ACMO = 40/60)
In the reactor, 1.0 part by mass of styrene, 2.0 parts by mass of acryloylmorpholine, 10 parts by mass of toluene, and 0.001 part by mass of azobisisobutyronitrile were added and heated to 80 ° C. After completion of the polymerization, the reaction solution was put into a large amount of hexane, the copolymerized oligomer was separated, and a compound O8 was obtained through filtration, washing and drying steps. This copolymer oligomer was confirmed to have a weight average molecular weight of 100,000 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O8 was a copolymer of styrene and acryloylmorpholine, and the composition was approximately styrene: acryloylmorpholine = 40: 60.

<Synthesis of Compound O9>
(Styrene / ACMO = 40/60)
In the reactor, 1.0 part by mass of styrene, 2.0 parts by mass of acryloylmorpholine, 10 parts by mass of toluene, and 0.3 parts by mass of azobisisobutyronitrile were added and heated to 80 ° C. After completion of the polymerization, the reaction solution was poured into a large amount of hexane, the copolymerized oligomer was separated, and Compound O9 was obtained through filtration, washing and drying steps. This copolymer oligomer was confirmed to have a weight average molecular weight of 1400 by GPC analysis based on standard polystyrene.

  From the NMR spectrum, compound O9 was a copolymer of styrene and acryloylmorpholine, and the composition was substantially styrene: acryloylmorpholine = 40: 60.

  Table 2 shows the composition of the oligomer synthesized as described above.

＜ポリエステルＰの合成＞
本発明において可塑剤として用いられるポリエステルＰについて、以下のようにして合成した。

<Synthesis of polyester P>
Polyester P used as a plasticizer in the present invention was synthesized as follows.

  In a nitrogen atmosphere, 4.85 g of dimethyl terephthalate, 4.4 g of 1,2-propylene glycol, 6.8 g of p-toluic acid, and 10 mg of tetraisopropyl titanate were mixed and stirred at 140 ° C. for 2 hours. Stirring was carried out at ° C for 16 hours. Next, the temperature was lowered to 170 ° C., and unreacted 1,2-propylene glycol was distilled off under reduced pressure to obtain polyester P.

Acid value: 0.1
Number average molecular weight: 490
Dispersity: 1.4
Component content of molecular weight 300-1800: 90%
Hydroxy (hydroxyl) value: 0.1
Hydroxy group (hydroxyl group) content: 0.04%
[Example 101]
(Preparation of λ / 4 retardation film 101)
<Preparation of fine particle dispersion 1>
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to prepare a fine particle dispersion 1.
<Preparation of fine particle additive solution 1>
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. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass <Dope solution>
A dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate was added to a pressurized dissolution tank containing a solvent while stirring. This was completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. A dope solution was prepared by filtration using 244.

上記組成物を密閉容器に投入し、攪拌しながら溶解してドープ液を調製した。次いで、無端ベルト流延装置を用い、ステンレスベルト支持体上に均一に流延した。 In addition, the compounds O1-O9 and the polyester P used the compound synthesize | combined by the said synthesis example, and the sugar ester compound A used the compound represented with the following structural formula.
<Composition of dope solution>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acylate (a) 100 parts by mass Compound O1 10.0 parts by mass Sugar ester compound A (the following structural formula) 5.0 parts by mass Polyester P 2.5 parts by mass UV absorber ( Tinuvin 928 (manufactured by BASF Japan Ltd.)) 2.0 parts by mass Particulate additive solution 1 1 part by mass

The composition was put into a closed container and dissolved with stirring to prepare a dope solution. Then, using an endless belt casting apparatus, it was cast uniformly on a stainless belt support.

  On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film was 75%, and the film was peeled off from the stainless steel belt support. The peeled cellulose ester film was stretched in the width direction using a tenter while applying heat. Next, drying was terminated while transporting the drying zone with a number of rolls, and the ends sandwiched between tenter clips were slit with a laser cutter, and then wound.

  The obtained film was stretched obliquely to a draw ratio of 2.0 times at 185 ° C. to obtain a λ / 4 retardation film 101. Table 3 shows the film thickness, in-plane retardation, wavelength dispersion Ro (550) / Ro (650), and elongation at break of the λ / 4 retardation film 101 obtained.

(1) Measurement of Ro (450), Ro (550), Ro (650) The average refraction of a film sample at wavelengths of 450 nm, 550 nm, and 650 nm using an Abbe refractometer and a spectral light source in an environment of 23 ° C. and 55% Rh. The rate was measured. Moreover, the thickness of the film was measured using a commercially available micrometer. Under the same environment, the above-mentioned average refractive index and film thickness are input into the following formula using AxoScan manufactured by Axometric to measure the retardation of the film at wavelengths of 450 nm, 550 nm, and 650 nm, and the in-plane retardation value Ro is obtained. The direction of the slow axis with respect to the width direction of the film is also measured at the same time. An in-plane phase difference of wavelength λ was defined as Ro (λ).

Ro (λ) = (nx−ny) × d
(In the formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, and d is the film thickness (nm).)
(2) Measurement of elongation at break The stress at break in the slow axis direction of the λ / 4 retardation film produced using a tensile tester (Tensilon; manufactured by A & C Co., Ltd.) in an environment of 23 ° C. and 55% Rh. (MPa) was measured. The breaking stress multiplied by the film thickness was calculated as the breaking elongation (N) and evaluated according to the following criteria.

◎: 60N or more ○: 50N or more and less than 60N ×: less than 50N
A 120 μm-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times).

  This was immersed in an aqueous solution composed 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. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

  The produced λ / 4 retardation film 101 was bonded to one side of the polarizer using a 5% polyvinyl alcohol aqueous solution as an adhesive. At that time, the lamination was performed so that the transmission axis of the polarizer and the slow axis of the λ / 4 retardation film were oriented at 45 °. On the other surface of the polarizer, a Konica Minolta-tack film KC6UA (manufactured by Konica Minolta Opto Co., Ltd.) was similarly subjected to alkali saponification treatment to form a circularly polarizing plate.

さらに、発光層上に電子が効率的に注入できるような仕事関数の低い第１の陰極としてカルシウムを真空蒸着法により４ｎｍの厚さで製膜し、第１の陰極上に第２の陰極としてアルミニウムを２ｎｍの厚さで製膜した。ここで、第２の陰極として用いたアルミニウムはその上に形成される透明電極をスパッタリング法により製膜する際に、第１の陰極であるカルシウムが化学的変質をすることを防ぐ役割がある。以上のようにして、有機発光層を得た。次に、陰極上にスパッタリング法によって透明導電膜を８０ｎｍの厚さで製膜した。ここで透明導電膜としてはＩＴＯを用いた。さらに、透明導電膜上にＣＶＤ法によって窒化珪素を２００ｎｍ製膜することで、絶縁膜とした。 (Preparation of organic electroluminescence display device 101)
A reflective electrode made of chromium having a thickness of 80 nm is formed on a glass substrate by sputtering, ITO is formed on the reflective electrode as an anode by sputtering to a thickness of 40 nm, and poly (3,4-layer) is formed on the anode as a hole transport layer. A light emitting layer of each of RGB was formed to a thickness of 100 nm using ethylenedioxythiophene) -polystyrene sulfonate (PEDOT: PSS) by a sputtering method with a thickness of 80 nm and a shadow mask on the hole transport layer. As a red light emitting layer, tris (8-hydroxyquinolinate) aluminum (Alq ₃ ) and a luminescent compound [4- (dicyanomethylene) -2-methyl-6 (p-dimethylaminostyryl) -4H-pyran] (DCM ) Were co-evaporated (mass ratio 99: 1) to form a thickness of 100 nm. The green light-emitting layer was formed with a thickness of 100 nm by co-evaporating Alq ₃ as a host and the light-emitting compound coumarin 6 (mass ratio 99: 1). The blue light-emitting layer was formed with a thickness of 100 nm by co-evaporating BAlq and a light-emitting compound Perylene as a host (mass ratio 90:10).

Further, as a first cathode having a low work function so that electrons can be efficiently injected onto the light-emitting layer, calcium is deposited to a thickness of 4 nm by a vacuum deposition method, and a second cathode is formed on the first cathode. Aluminum was formed to a thickness of 2 nm. Here, the aluminum used as the second cathode has a role to prevent the calcium as the first cathode from being chemically altered when the transparent electrode formed thereon is formed by sputtering. As described above, an organic light emitting layer was obtained. Next, a transparent conductive film with a thickness of 80 nm was formed on the cathode by sputtering. Here, ITO was used as the transparent conductive film. Furthermore, 200 nm of silicon nitride was formed on the transparent conductive film by a CVD method to form an insulating film.

  On the insulating film of the obtained organic electroluminescence display device, the circularly polarizing plate 101 is fixed with an adhesive so that the surface of the λ / 4 retardation film faces the surface of the insulating film, and the organic electroluminescence display device 101 is manufactured. did.

  The obtained organic electroluminescence display device 101 was evaluated according to the following criteria.

(3) Evaluation of light leakage of organic electroluminescence display device In a constant temperature and humidity chamber of 23 ° C. and 55% RH, a commercially available desk stand (MITSUBISHI inverter BB glitter) is installed at a location 60 cm from the surface of the display device. Illuminated and displayed a black image on the display device. After 1 hour, the luminance was measured at a viewing angle of 0.2 ° with a luminance meter (manufactured by Konica Minolta: CS-2000) installed at a position 1 m away from the surface of the display device. Further, an observer stood at a position 1 m away from the surface of the display device, and sensory evaluation of blackness and hue deviation was performed.

◎: visible tight black, luminance 2cd / ^{m 2} less than ○: visible tight black, × luminance is within 2cd / ^{m 2} or more 3 cd / ^{m 2:} looks tinted red or blue, or, luminance More than 3 cd / m ² (4) Evaluation of oblique hue of organic electroluminescence display device In a constant temperature and humidity chamber at 23 ° C. and 55% RH, a commercially available desk stand (MITSUBISHI inverter BB) is located 60 cm from the surface of the display device. and illuminate and display a black image on the display device. One hour later, the blackness level from the front of the display device and the blackness level from the direction of 45 ° from the normal line of the display device were visually evaluated, and the difference was compared.

◎: There is no change in blackness between the front and the squint. ○: A slight difference in blackness is seen between the front and the squint, but it does not matter. ×: The difference in external light reflection between the front and the squint. (5) Durability evaluation of organic electroluminescence display device In a constant temperature and humidity environment room at 23 ° C. and 55% RH, a commercially available desk stand (MITSUBISHI inverter BB glitter) is installed 60 cm from the surface of the display device. Illuminated and displayed a black image on the display device. After 1 hour, the luminance was measured at a viewing angle of 0.2 ° with a luminance meter (manufactured by Konica Minolta: CS-2000) installed at a position 1 m away from the surface of the display device. Next, the environment chamber was changed to a condition of 60 ° C. and 80% RH, and the organic electroluminescence display device displayed a black image. After 1 hour, the luminance was measured at a viewing angle of 2 ° with a luminance meter (manufactured by Konica Minolta: CS-2000) installed at a position 1 m away from the surface of the display device. Evaluation was performed based on the following criteria from the change in luminance before and after exposure to an environment of 60 ° C. and 80% RH.

A: The change in luminance is less than 5 times based on the measurement value at 23 ° C. and 55% RH. ○: The change in luminance is 5 to 10 times based on the measurement value at 23 ° C. and 55% RH. The change in luminance exceeds 10 times based on the measured value at 55 ° C. at 55 ° C. [Examples 102 to 106]
(Production of λ / 4 retardation films 102 to 106)
In the production of the λ / 4 retardation film 101, λ / 4 retardation films 102 to 106 were produced in the same manner as 101 except that the compound O1 was changed to the compounds O2 to O6. In the same manner as in Example 101, (1) measurement of Ro (450), Ro (550), Ro (650) and (2) measurement of elongation at break were performed.

(Production of circularly polarizing plates 102 to 106)
In the production of the circularly polarizing plate 101, circularly polarizing plates 102 to 106 were produced in the same manner except that the λ / 4 retardation film 102 to 106 was used instead of the λ / 4 retardation film 101.

(Production of organic electroluminescence display devices 102 to 106)
In the production of the organic electroluminescence display device 101, the organic electroluminescence display devices 102 to 106 were produced in the same manner except that the circularly polarizing plates 102 to 106 were used instead of the circularly polarizing plate 101. In the same manner as in Example 101, (3) Evaluation of light leakage of organic electroluminescence display device, (4) Evaluation of oblique hue of organic electroluminescence display device, (5) Durability evaluation of organic electroluminescence display device It was.

[Comparative Examples 1-3]
(Preparation of λ / 4 retardation films 1 to 3 for comparison)
In the production of the λ / 4 retardation film 101 according to the present invention, the comparative λ / 4 retardation film 1 was prepared in the same manner as in Example 101 except that the addition of the compound O1 was changed to no addition and the compounds O8 and O9. ~ 3 were made. In the same manner as in Example 101, (1) measurement of Ro (450), Ro (550), Ro (650) and (2) measurement of elongation at break were performed.

(Preparation of comparative polarizing plates 1 to 3)
In the production of the circularly polarizing plate 101 according to the present invention, the comparative circularly polarizing plates 1 to 3 were similarly prepared except that the comparative λ / 4 retardation films 1 to 3 were used instead of the λ / 4 retardation film 101. Was made.

(Preparation of comparative organic electroluminescence display devices 1 to 3)
In the production of the organic electroluminescence display device 101 of the present invention, comparative organic electroluminescence display devices 1 to 3 were produced in the same manner except that the comparative circularly polarizing plates 1 to 3 were used instead of the circularly polarizing plate 101. . In the same manner as in Example 101, (3) Evaluation of light leakage of organic electroluminescence display device, (4) Evaluation of oblique hue of organic electroluminescence display device, (5) Durability evaluation of organic electroluminescence display device It was. The results are shown in Table 3.

表３の結果から明らかなように、実施例１０１〜１０６の本発明に係るλ／４位相差フィルムは比較例１〜４の比較用のλ／４位相差フィルムに比べて、黒表示時の光漏れ、斜め色相、耐久黒表示時光漏れの評価において、いずれも優れた性能を発揮している。

As is apparent from the results in Table 3, the λ / 4 retardation films according to the present invention in Examples 101 to 106 are more suitable for black display than the λ / 4 retardation films for comparison in Comparative Examples 1 to 4. In the evaluation of light leakage, oblique hue, and light leakage at the time of durable black display, all show excellent performance.

[Example 107]
(Preparation of λ / 4 retardation film 107)
In the production of the λ / 4 retardation film 101, a λ / 4 retardation film 107 was produced in the same manner as 101 except that the compound O1 was changed to the compound O7. In the same manner as in Example 101, (1) measurement of Ro (450), Ro (550), Ro (650) and (2) measurement of elongation at break were performed.

(Preparation of circularly polarizing plate 107)
A circularly polarizing plate 107 was produced in the same manner as in the production of the circularly polarizing plate 101 except that the λ / 4 retardation film 107 was used instead of the λ / 4 retardation film 101.

(Preparation of organic electroluminescence display device 107)
An organic electroluminescence display device 107 was produced in the same manner as in the production of the organic electroluminescence display device 101 except that the circularly polarizing plate 107 was used instead of the circularly polarizing plate 101. (3) Evaluation of light leakage of organic electroluminescence display device, (4) Evaluation of oblique hue of organic electroluminescence display device, and (5) Endurance evaluation of organic electroluminescence display device in the same manner as Example 101 .

[Examples 108 to 110]
(Production of λ / 4 retardation film 108 to 110)
In the production of the λ / 4 retardation film 102, the λ / 4 retardation film was prepared in the same manner as 102 except that the addition amount of the compound O2 was changed from 10% to 2.5%, 20%, and 5%, respectively. 108-110 were produced. In the same manner as in Example 102, (1) measurement of Ro (450), Ro (550), Ro (650) and (2) measurement of elongation at break were performed.

(Production of circularly polarizing plates 108 to 110)
In the production of the circularly polarizing plate 102, circularly polarizing plates 108 to 110 were produced in the same manner except that the λ / 4 retardation film 108 to 110 was used instead of the λ / 4 retardation film 102.

(Production of organic electroluminescence display devices 108 to 110)
Organic electroluminescence display devices 108 to 110 were produced in the same manner except that the circularly polarizing plates 108 to 110 were used instead of the circularly polarizing plate 102 in the production of the organic electroluminescence display device 102. In the same manner as in Example 102, (3) Evaluation of light leakage of organic electroluminescence display device, (4) Evaluation of oblique hue of organic electroluminescence display device, (5) Durability evaluation of organic electroluminescence display device It was.

[Examples 201 to 205]
(Production of λ / 4 retardation films 201-205)
In the production of the λ / 4 retardation film 102, the same as 102 except that the cellulose acylate (a) was changed to the cellulose acylate (b), (c), (d), (e), (f). Λ / 4 retardation films 201 to 205 were produced by the method. In the same manner as in Example 102, (1) measurement of Ro (450), Ro (550), Ro (650) and (2) measurement of elongation at break were performed.

(Production of circularly polarizing plates 201-205)
In the production of the circularly polarizing plate 102, circularly polarizing plates 201 to 205 were produced in the same manner except that the λ / 4 retardation films 201 to 205 were used instead of the λ / 4 retardation film 102.

(Production of organic electroluminescence display devices 201-205)
In the production of the organic electroluminescence display device 102, the organic electroluminescence display devices 201 to 205 were produced in the same manner except that the circular polarization plates 201 to 205 were used instead of the circular polarization plate 102. (3) Evaluation of light leakage of organic electroluminescence display device, (4) Evaluation of oblique hue of organic electroluminescence display device, and (5) Durability evaluation of organic electroluminescence display device in the same manner as in Example 102 .

[Comparative Example 4]
(Preparation of comparative λ / 4 retardation film 4)
In the production of the λ / 4 retardation film 102 according to the present invention, a comparative λ / 4 retardation film was produced in the same manner as in Example 102 except that the cellulose acylate (a) was changed to the cellulose acylate (g). 4 was produced. In the same manner as in Example 102, (1) measurement of Ro (450), Ro (550), Ro (650) and (2) measurement of elongation at break were performed.

(Preparation of comparative circularly polarizing plate 4)
In the production of the circularly polarizing plate 102 according to the present invention, a comparative circularly polarizing plate 4 was produced in the same manner except that the comparative λ / 4 retardation film 4 was used instead of the λ / 4 retardation film 102.

(Production of comparative organic electroluminescence display device 4)
In the production of the organic electroluminescence display device 102 of the present invention, a comparative organic electroluminescence display device 4 was produced in the same manner except that the comparative circularly polarizing plate 4 was used instead of the circularly polarizing plate 102. (3) Evaluation of light leakage of organic electroluminescence display device, (4) Evaluation of oblique hue of organic electroluminescence display device, and (5) Durability evaluation of organic electroluminescence display device in the same manner as in Example 102 .

以上の結果から明らかなように実施例１０７〜１１０、及び２０１〜２０５の本発明の有機エレクトロルミネッセンス表示装置は、比較例４の比較用有機エレクトロルミネッセンス表示装置に比べて、黒表示時の光漏れ、斜め色相変動、耐久黒表示時光漏れの評価において、優れた性能を発揮している。 The results are shown in Table 4.

As is clear from the above results, the organic electroluminescence display devices of Examples 107 to 110 and 201 to 205 of the present invention have a light leakage during black display as compared with the comparative organic electroluminescence display device of Comparative Example 4. Excellent performance in evaluation of slant hue fluctuation and light leakage during durable black display.

P _L linear polarizing film P λ _{/ 4} λ _{/ 4} retardation film Ts transparent substrate Et transparent electrode _{O L-emitting} layer Er light reflective electrode

Claims (6)

An organic electroluminescence display device comprising at least a light reflecting electrode, a light emitting layer, a transparent electrode, a circularly polarizing plate having a λ / 4 retardation film and a linearly polarizing film,
The λ / 4 retardation film is composed of a single layer, contains cellulose acylate satisfying the following formulas (1) and (2), has a weight average molecular weight in the range of 1500 to 80000, and is intrinsic An organic electroluminescence display device comprising an oligomer having a negative birefringence value.
Formula (1): 2.0 ≦ Z1 <3.0
Formula (2): 0.5 ≦ X
(In formulas (1) and (2), Z1 represents the total acyl group substitution degree of cellulose acylate, and X represents the sum of propionyl group substitution degree and butyryl group substitution degree of cellulose acylate.)   The ratio of the in-plane retardation value Ro (550) of light having a wavelength of 550 nm to the in-plane retardation value Ro (650) of light having a wavelength of 650 nm of the λ / 4 retardation film (Ro (550) / Ro ( 650)) is within the range of 0.83 to 0.97. 2. The organic electroluminescent display device according to claim 1, wherein   The organic electroluminescence display device according to claim 1, wherein the oligomer having a negative intrinsic birefringence value includes a styrene derivative structure. 4. The organic electroluminescence display device according to claim 1, wherein a total substitution degree Z <b> 1 of the cellulose acylate satisfies the following formula (3): 5.
Formula (3): 2.0 ≦ Z1 <2.5   The content of the oligomer having a negative intrinsic birefringence value is in the range of 5 to 20% by mass with respect to the cellulose acylate, according to any one of claims 1 to 4. The organic electroluminescence display device described.   The organic electroluminescence display device according to any one of claims 1 to 5, wherein a weight average molecular weight of the oligomer having a negative intrinsic birefringence value is in a range of 1500 to 30000.

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