KR20160017062A - Long optical film, circularly polarizing plate provided with long optical film, and organic electroluminescent display device - Google Patents

Abstract

Aspect of the present invention contains a cellulose derivative and a silica-based fine particles, the angle is 40 to 50 ° is the longitudinal direction and the slow axis forming, and the retardation Ro ₅₅₀ a plane at a wavelength of 550nm 120nm than 160nm or less, the following expression (1) to (3). 1.8 < / = (1) 0.3? X _ES? 1.5 (2) 0.3? X _ETH ? (3) wherein X _ES is the average degree of ester substitution of the cellulose derivative, X _ETH is the ether average degree of substitution of the cellulose derivative, and Y is the total degree of substitution of the cellulose derivative.

Description

TECHNICAL FIELD [0001] The present invention relates to a long optical film, a circularly polarizing plate having the long optical film, and an organic electroluminescence display device.

The present invention relates to a long optical film, a circularly polarizing plate having the long optical film and an organic electroluminescence display.

2. Description of the Related Art In recent years, liquid crystal display devices have been widely used as general display devices. A liquid crystal display device is required to have high display performance and durability, and it is required that good contrast and color balance can be obtained with a wide viewing angle. In addition, in recent years, there is a demand for power saving, and a demand for a viewing angle and a display performance is further increased. Under such circumstances, an organic EL display using organic electroluminescence (hereinafter abbreviated as organic EL) as a backlight has attracted attention as a display device of a new type. The organic EL display has low power consumption, high front contrast, and excellent viewing angle characteristics.

On the other hand, in the organic EL display, in order to efficiently extract the light from the light emitting layer to the viewer side, a metal material having high light reflectivity is used as an electrode layer constituting the cathode, and a reflection plate And a member is provided on the side opposite to the light-extracting surface. Therefore, in the organic EL display, there is a problem that the external light is reflected by the light-extracting reflecting member to cause the projection, and the contrast is greatly lowered in a high-illuminated environment.

In order to solve such a problem, for example, there is a method of using a circularly polarizing element for preventing external light reflection on a mirror surface (see, for example, Patent Document 1).

However, in such a retardation plate, there arises a problem that a distribution occurs in a polarization state at each wavelength with respect to white light, and is converted into colored polarized light. This is because the material constituting the phase difference plate has a wavelength dispersion property with respect to the retardation.

In order to solve such a problem, for example, a λ / 4 wave plate in which the phase difference of birefringence light is 1/4 wavelength and a λ / 2 wave plate in which the phase difference of birefringence light is 1/2 wavelength, (See, for example, Patent Document 2).

However, such a retardation plate has a problem in that it can not attain thinning in addition to the complicated manufacturing process.

Therefore, as a technique for obtaining a wide-band? / 4 retardation film with a single-layer structure, a polymer film obtained by copolymerizing a monomer unit of a polymer having positive refractive index anisotropy and a monomer unit having negative birefringence is uniaxially stretched to obtain a? / 4 retardation (See, for example, Patent Document 3). Further, an optical film having an optical compensation function and a function as a polarizing plate protective film was studied (see, for example, Patent Document 4). From the viewpoint of excellent production suitability of the polarizing plate, cellulose ester resins are preferably used for these films. In addition, a method of adding a compound inhibiting water coordination to the ester group of the cellulose ester resin, which is the main component of the film, has been proposed in order to suppress the phase difference fluctuation due to the humidity fluctuation (see, for example, Patent Document 5) .

However, the retardation film obtained by the method described in Patent Document 3 has a problem that the polarizer is poor in adhesiveness when the polarizer is manufactured. In the films obtained by the methods described in Patent Documents 3 and 4, a cellulose ester resin is preferably used, but the cellulose ester resin is liable to cause a phase difference variation originally, and a phase difference variation is likely to occur due to humidity variation.

Further, in general, when a long optical film is produced, a matting agent is added from the viewpoint of suppressing an increase in haze. However, when the additive described in Patent Document 5 is added to a cellulose ester film containing a mat agent, there is a problem that the mat agent is aggregated and the haze increases. Further, in order to produce a? / 4 film, it is necessary to stretch the film raw material at a high magnification, resulting in a problem that the brittleness of the resulting film is lowered.

Japanese Patent Application Laid-Open No. 8-321381 Japanese Patent Application Laid-Open No. 10-68816 International Publication No. 2000/026705 Japanese Patent Laid-Open No. 2007-47537 Japanese Patent Application Laid-Open No. H06-067218

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a long optical film which exhibits sufficient retardation, exhibits a retardation in retardation due to humidity fluctuations, is excellent in adhesion to polarizers and embrittlement, , A circular polarizer plate having the long optical film and an organic electroluminescence display device.

Aspect of the present invention contains a cellulose derivative and a silica-based fine particles, the angle is 40 to 50 ° is the longitudinal direction and the slow axis forming, and the retardation Ro ₅₅₀ a plane at a wavelength of 550nm 120nm than 160nm or less, the following expression (1) to (3).

1.8 < / = (One)

0.3? X _ES? 1.5 ... (2)

0.3? X _ETH ? (3)

Wherein X _ES is the average degree of ester substitution of the cellulose derivative, X _ETH is the ether average degree of substitution of the cellulose derivative, and Y is the total degree of substitution of the cellulose derivative)

These and other objects, features and advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view for explaining a contraction magnification in oblique stretching. Fig.
2 is a schematic view showing an example of a rail pattern of a warp stretcher applicable to manufacture of an optical film according to an embodiment of the present invention.
Fig. 3 is a schematic view showing a method of producing an optical film according to an embodiment of the present invention (an example in which the film is loosened from a long film raw roll and then obliquely drawn).
Fig. 4 is a schematic view showing a method for producing an optical film according to an embodiment of the present invention (an example in which a long film fabric is continuously obliquely drawn without winding). Fig.
5 is a schematic diagram showing an example of a configuration of an organic EL display according to an embodiment of the present invention.

The inventors of the present invention have made intensive studies and have found out that the above problems can be solved by setting the ratio of the substituent of the cellulose derivative to the predetermined range in the long optical film containing the matzine silica-based fine particles and the cellulose derivative, Thereby completing the invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

<Long optical film>

The long optical film (hereinafter, simply referred to as an optical film or a retardation film) of the present embodiment is characterized by an angle formed by the long direction and the slow axis is 40 to 50 degrees. That is, the angle formed by the longitudinal direction of the long optical film and the slow axis in the plane is 40 to 50 degrees. The long optical film has an in-plane retardation Ro ₅₅₀ at a wavelength of 550 nm of 120 nm or more and 160 nm or less. Further, the long optical film contains a cellulose derivative and silica-based fine particles, and the cellulose derivative satisfies the following formulas (1) to (3). Since the long optical film of this embodiment has optical characteristics such that the retardation Ro ₅₅₀ and the in-plane retardation Ro ₅₅₀ are within the above ranges, a retardation of substantially? / 4 can be imparted to light of a broad band of visible light. In addition, since the long optical film contains, as a constituent component, a cellulose derivative whose substituent ratio is adjusted so as to satisfy the following formulas (1) to (3), the optical performance (color performance, The effect of inhibiting the increase in haze is sufficiently obtained, and further excellent embrittlement is imparted to the film. Hereinafter, the long optical film of the present embodiment will be described in the order of optical characteristics and constituent components.

1.8 &lt; / = (One)

0.3? X _ES? 1.5 ... (2)

0.3? X _ETH ? (3)

X _ES is the average degree of ester substitution of the cellulose derivative, X _ETH is the ether average degree of substitution of the cellulose derivative, and Y is the total degree of substitution of the cellulose derivative.

In the present specification, the term &quot; long &quot; means a film having a length of at least about 5 times or more, preferably 10 times or more, with respect to the width of the film. The term &quot; optical film &quot; refers to a film having an optical function of imparting a desired retardation to transmitted light. Examples of the optical function include a function of converting linearly polarized light of a specific wavelength into elliptically polarized light or circularly polarized light, or converting elliptically polarized light or circularly polarized light into linearly polarized light. Particularly, an optical film having characteristics in which the in-plane retardation of the film is about 1/4 of a predetermined light wavelength (usually visible light region) is referred to as a? / 4 retardation film. The optical film of the present embodiment is a wide-band? / 4 retardation film having a retardation of about 1/4 of the wavelength in the wavelength range of visible light in order to convert linearly polarized light into almost complete circularly polarized light in a wide range of visible light wavelength desirable. In the present specification, the term &quot; phase difference of about 1/4 in the wavelength range of visible light &quot; means that the retardation value has a reverse wavelength dispersion characteristic with a longer retardation value in a wavelength range of 400 nm to 700 nm.

(Optical properties of film)

The in-plane retardation Ro in the optical film of the present embodiment is defined by the following formula.

Ro = (nx-ny) xd (nm)

(Where nx represents the refractive index in the geographical axial direction x where the refractive index becomes the maximum in the in-plane direction of the optical film, and ny represents the refractive index in the in-plane direction of the optical film in the direction y orthogonal to the geographical axial direction x , And d (nm) represents the thickness of the optical film)

Also, Ro can be measured using an automatic birefringence meter under an environment of a temperature of 23 DEG C and a relative humidity of 55% RH. Examples of the automatic birefringence index system include AxoScan manufactured by Axometrics, KOBRA-21ADH manufactured by Oji Keisei Kikuchi Co., Ltd., and the like.

Here, when the in-plane retardation of the optical film at a wavelength of 550 nm is Ro ₅₅₀ , the optical film of the present embodiment is characterized in that Ro ₅₅₀ is 120 nm or more and 160 nm or less. The in-plane retardation Ro ₅₅₀ at the wavelength of 550 nm is an in-plane retardation measured at a wavelength of 550 nm. Ro ₅₅₀ may be 120 nm or more and 160 nm or less, preferably 130 nm or more and 150 nm or less, and more preferably 135 nm or more and 148 nm or less. When Ro ₅₅₀ is in the range of 120 nm or more and 160 nm or less (Ro ₅₅₀ is less than 120 nm or more than 160 nm), the retardation at a wavelength of 550 nm is not about 1/4 wavelength, When a polarizing plate is produced and applied to, for example, an organic EL display, the projection of the room lighting and the like may become large, and black may not be able to be expressed at the spot.

Further, a phase difference within the surface of the optical film at a wavelength of 450nm optical film within a phase difference with Ro _450, and wavelength 550nm surface of at when the Ro _550, the ratio of Ro ₄₅₀ for Ro ₅₅₀ (Ro ₄₅₀ / Ro ₅₅₀ ) Is preferably 0.70 or more and 0.98 or less, more preferably 0.75 or more and 0.92 or less, still more preferably 0.80 or more and 0.87 or less. The in-plane retardation Ro ₄₅₀ at the wavelength of 450 nm is an in-plane retardation measured at a wavelength of 450 nm. When Ro ₄₅₀ / Ro ₅₅₀ exceeds the range of 0.70 or more and 0.98 or less (when Ro ₄₅₀ / Ro ₅₅₀ is less than 0.70 or exceeds 0.98), the optical film does not exhibit the reverse wavelength dispersion characteristic with an appropriate retardation, , There is a tendency to cause a color change due to a color change or a humidity environment when a circularly polarizing plate is produced.

In the optical film of this embodiment, the angle formed by the longitudinal direction and the slow axis is 40 to 50 degrees, preferably 42 to 48 degrees, and more preferably 43 to 47 degrees. Since the optical film of this embodiment has such a slow axis, the roll-shaped raw film and the roll-shaped polarizer film having transmission axes parallel to each other in the longitudinal direction are respectively wound, and the roll- The circular polarizing plate can be easily manufactured by bonding. Thus, the cut loss of the film can be reduced. As a method of setting the range of the slow axis in the long direction to such a range, there is a method of performing warp stretching, which will be described later, on the film before the film is formed.

(Constituent components of the film)

Next, the constituent components of the optical film of the present embodiment will be described. The optical film is composed of a resin component (a resin composition containing a cellulose derivative) which is a main component and an additive component (including a component other than the resin component and a matting agent such as silica-based fine particles).

(A resin composition containing a cellulose derivative)

The optical film contains, as a main component, a cellulose derivative. In the present specification, the "main component" refers to a component contained in an amount of 55 mass% or more in the resin component constituting the optical film. Therefore, a resin composition containing 55 mass% or more of a cellulose derivative is used as the resin component constituting the optical film.

The cellulose derivative has a structure in which the hydroxyl group of cellulose is substituted by a substituent, and specifically, a structure in which a substituent is bonded to the glucose skeleton by an ester bond or an ether bond which will be described later. The optical film of the present embodiment is characterized in that the substitution degree of the substituent in the glucose skeleton satisfies the following formulas (1) to (3). The "substituent group of the glucose skeleton" includes a "substituent group which is ester-bonded to the glucose skeleton" and a "substituent group which is ether-bonded to the glucose skeleton" described later.

1.8 &lt; / = (One)

0.3? X _ES? 1.5 ... (2)

0.3? X _ETH ? (3)

Wherein X _ES is the average degree of ester substitution of the cellulose derivative, X _ETH is the ether average degree of substitution of the cellulose derivative, and Y is the total degree of substitution of the cellulose derivative)

In addition, the cellulose derivative has glucose skeleton units represented by the following general formula.

[Chemical Formula 1]

(A substituent which is located, R ² is 2-position of the glucose skeleton in the formula, R ³ is a substituent located at the 3-position of glucose backbone, R ⁶ is a substituent located at the 6-position of the glucose backbone. R ^2, R ³ and R ⁶ may be selected so that the degree of substitution satisfies the above formulas (1) to (3), and each represents a hydrogen atom or a substituent)

As shown in the formula (1), the total substitution degree Y is 1.8 or more and 2.6 or less, preferably 1.9 or more and 2.4 or less, more preferably 2.0 or more and 2.3 or less. When the total degree of substitution Y is less than 1.8, the type of the solvent to be dissolved alone is limited, and the water absorption of the film is increased, and the phase difference tends to fluctuate due to the humidity fluctuation. On the other hand, when the total degree of substitution Y exceeds 2.6, sufficient phase difference manifestation is not exerted, and the resin tends to be expensive and expensive. In the present embodiment, the total substitution degree Y is represented by the sum of the ester average substitution degree X _ES and the ether average substitution degree X _ETH . In the present specification, the term "total degree of substitution" refers to the average total degree of substitution. The term "total degree of substitution" refers to the average total degree of substitution, and represents the number average value of the esterified or etherified hydroxy groups in the three hydroxyl groups (hydroxyl groups) of the glucose skeleton constituting cellulose. Lt; / RTI &gt; to 3.0. Therefore, when the total substitution degree Y is 1.8 or more and 2.6 or less, the ratio of the hydroxyl group is 0.4 or more and 1.2 or less. When the proportion of the hydroxyl group is in this range, the hydrogen bonding property between the cellulose derivatives is enhanced, so that the brittleness of the resulting optical film is improved. If the ratio of the hydroxy groups is in this range, the optical film is easy to develop a desired in-plane retardation value Ro when the film thickness is, for example, 20 to 60 占 퐉.

As shown in the formula (2), the ester average degree of substitution X _ES is 0.3 or more and 1.5 or less, preferably 0.5 or more and 1.4 or less, and more preferably 0.7 or more and 1.4 or less. When the ester average degree of substitution X _ES is less than 0.3, the transparency of the film tends to be lowered. On the other hand, when the ester average degree of substitution X _ES exceeds 1.5, the absorbency of the film becomes high, and the phase difference tends to fluctuate due to the humidity fluctuation.

As shown in the formula (3), the ether average degree of substitution X _ETH is 0.3 or more and 2.3 or less, preferably 0.5 or more and 1.9 or less, and more preferably 0.5 or more and 1.6 or less. When the ether average degree of substitution X _ETH is less than 0.3, the total substitution degree Y of the film substituted with the ester on the basis of the range shown in the above formula (2) does not satisfy the lower limit value of 1.8, and the retardation fluctuates due to the humidity fluctuation There is a tendency. On the other hand, when the ether average degree of substitution X _ETH exceeds 2.3, there is a tendency that the adhesiveness is not excellent and the manufacturability is poor when the circularly polarizing plate is produced by the method described later, , The total degree of substitution Y of the film substituted with the ester is more than 2.6, which is the upper limit, and the obtained film tends not to exhibit sufficient retardation.

Hereinafter, substituent groups of the cellulose derivative for satisfying the above-mentioned formulas (1) to (3) of the cellulose derivative of the present embodiment will be described.

(Substituent group ester-bonded with glucose skeleton)

The cellulose derivative of the present embodiment has a substituent group ester-bonded to the glucose skeleton so as to satisfy the formula (2).

As the substituent group ester-bonded to the glucose skeleton, R ² , R ^3, and R ^{6 in} the general formula of the cellulose derivative include an aliphatic acyl group and an aromatic group. The aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group. The aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group, preferably an aromatic hydrocarbon group.

The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 10 carbon atoms. Specific examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthryl group, a biphenyl group and a terphenyl group, and a phenyl group, a naphthyl group and a biphenyl group are preferable, and a phenyl group is more preferable.

The aromatic heterocyclic group preferably contains at least one of an oxygen atom, a nitrogen atom or a sulfur atom. Specific examples of the heterocycle include furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole, But are not limited to, oxadiazole, quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, phthyridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole , Benzothiazole, benzotriazole, tetrazaine, and the like. The aromatic heterocyclic group is particularly preferably a pyridyl group, a thiophenyl group, a triazinyl group or a quinolyl group.

Specific examples of the aromatic group bonded through the glucose skeleton and the ether bond include benzyl ether, 4-phenylbenzyl ether, 4-thiomethylbenzyl ether, 4-methoxybenzyl ether, 2,4,5- , 5-trimethoxybenzyl ether, and the like. Other examples of the aromatic group bonded by the ether linkage to the glucose skeleton include 2-thienyl ether, 3-thienyl ether, 4-thiazolyl ether, 2-thiazolyl ether, 2-furyl ether, Pyrrolyl ether, 3-imidazolyl ether, 2-triazolyl ether, 1-pyrrolyl ether, 1-imidazolyl ether, Pyridyl ether, 2-pyridyl ether, 2-pyrimidyl ether, 2-quinolyl ether, 2-quinolyl ether, 2- Benzothiazolyl ether, 2-benzothiazolyl ether, 2-benzoxazolyl ether, 2-benzothiazolyl ether, 2-benzothiazolyl ether, 2-benzimidazolyl ether, and the like.

Preferable examples of the aromatic acyl group include benzoyl group, phenylbenzoyl group, 4-methylbenzoyl group, 4-thiomethylbenzoyl group, 4-methoxybenzoyl group, 4-heptylbenzoyl group, 2,4,5-trimethylbenzoyl group, 3,4,5-trimethoxybenzoyl group and naphthoyl group. Other examples of the aromatic acyl group include 2-thiophenecarboxylic acid ester, 3-thiophenecarboxylic acid ester, 4-thiazolecarboxylic acid ester, 2-thiazolecarboxylic acid ester, Ester, 3-furancarboxylic acid ester, 3-furancarboxylic acid ester, 4-oxazole carboxylic acid ester, 2-oxazole carboxylic acid ester, Pyrrolecarboxylic acid ester, 3-pyridinecarboxylic acid ester, 2-pyridinecarboxylic acid ester, 3-pyridinecarboxylic acid ester, Pyrimidine carboxylic acid ester, 2-pyridinecarboxylic acid ester, 2-quinolinecarboxylic acid ester, 2-quinoxaline carboxylic acid ester, 4-pyrimidine carboxylic acid ester, Carlsbad Benzoic acid esters, 2-benzofuran carboxylic acid esters, 2-indole carboxylic acid esters, 2-benzoquinolinecarboxylic acid esters, 2-benzoquinolinecarboxylic acid esters, Thiazolecarboxylic acid esters, 2-benzoxazole carboxylic acid esters and 2-benzimidazole carboxylic acid esters. These aromatic groups may further have a substituent, but it is preferable that they do not have a substituent group containing a carboxyl group (-C (= O) O-). When these aromatic groups contain a carboxyl group, the hydrophilicity of the film increases, and the humidity dependency of optical properties tends to be deteriorated. It is preferred that the aromatic group is unsubstituted or substituted with an alkyl group or an aryl group.

An aliphatic acyl group refers to a group in which R of - (C = O) R is an aliphatic group. The aliphatic group moiety may be any of linear, branched and cyclic aliphatic groups. The aliphatic acyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and even more preferably 1 to 6 carbon atoms. The aliphatic acyl group may have a substituent at the aliphatic group site. The aliphatic acyl group is preferably unsubstituted, more preferably an acetyl group, a propionyl group, or a butyryl group.

(Substituent group bonded to the glucose skeleton through an ether bond)

The cellulose derivative of the present embodiment has a substituent group ether-bonded to the glucose skeleton so as to satisfy the formula (3). This is because when the majority of the substituents bonded to the glucose skeleton of the cellulose derivative is an ester group, the obtained optical film tends to undergo birefringence change due to the interaction between the ester group and water. As a result, a color change or a change in reflection performance is promoted with respect to a change in humidity, but introduction of an ether group as a substituent improves the hydrophobicity of the cellulose derivative. Further, since the ether group has a small interaction with water and hardly causes birefringence change, it is considered that the change in color tone and the change in reflection performance with respect to humidity change are improved.

Examples of the substituent group ether-bonded to the glucose skeleton include the case where R ² , R ³ and R ^{6 in} the general formula of the cellulose derivative are an aliphatic hydrocarbon group or an aromatic group. When R ² , R ^3, and R ⁶ are aromatic groups, R ² , R ^3, and R ⁶ may be contained in a substituent having a multiple bond (multi-bonding group), which will be described later.

Among these, preferable examples of the substituent group which is ether-bonded to the glucose skeleton are a substituent group in which the glucose skeleton and the aliphatic hydrocarbon group are ether-bonded, and the change in color tone and the reflection performance against humidity change are suppressed in the organic EL display manufactured using the obtained optical film Do. Among the aliphatic hydrocarbon groups, an unsubstituted aliphatic hydrocarbon group is preferable.

The unsubstituted aliphatic hydrocarbon group is an aliphatic group containing no atoms other than carbon atoms and hydrogen atoms, and may be any of linear, branched and cyclic groups. The aliphatic hydrocarbon group is preferably an alkyl group, more preferably a straight-chain alkyl group. The number of carbon atoms of the aliphatic hydrocarbon group is preferably 1 to 20, more preferably 1 to 12, and even more preferably 1 to 6. Among them, a methyl group and an ethyl group are particularly preferable. When such an aliphatic hydrocarbon group of the carbon number is ether-bonded with the glucose skeleton, even when the resulting optical film has a small thickness, change in color tone and change in reflection performance under external light are suppressed when used in an organic EL display.

When the aliphatic hydrocarbon group has a substituent, it is preferable that it does not have a substituent group containing a carboxyl group (-C (= O) O-). If it contains a carboxyl group, the hydrophilicity increases, and the humidity dependency of optical properties tends to be deteriorated. The aliphatic hydrocarbon group having a substituent includes, for example, a hydroxypropyl group.

The cellulose derivative of the present embodiment has a substituent group ester-bonded to the glucose skeleton so as to satisfy the range of the ester average degree of substitution X _ES defined in the formula (2), and the ether average degree of substitution X _ETH And has a substituent group which is ether-linked with the glucose skeleton to satisfy the range. In addition, the cellulose derivative satisfies the range of the total degree of substitution Y defined in the formula (1) by combining these substituents.

(Substituent having multiple bonds (multi-bonding group))

The cellulose derivative of the present embodiment preferably has a multiple binding group. The multiple bonding group is not particularly limited as long as it has at least one double bond or triple bond and has an absorption maximum at a wavelength of 220 nm or more and 350 nm or less. The average degree of substitution of the multiple binding groups in the cellulose derivative is preferably 0.3 or more and 0.7 or less, more preferably 0.3 or more and 0.6 or less, still more preferably 0.3 or more and 0.5 or less. The cellulose derivative has a multi-bonding group exhibiting an absorption maximum and an average degree of substitution in the above-mentioned range, so that the reverse wavelength dispersion characteristic of the obtained optical film can be further improved.

Examples of such multiple bonding groups include substituents having an aromatic structure. Such an aromatic group may be a combination of a double bond and a triple bond. The aromatic group may be bonded with an electron-withdrawing group or a functional group of an electron-donating group, and it is preferable that an electron-donating group is bonded to the aromatic group from the viewpoint of improving the wavelength dispersibility of the obtained optical film.

More specifically, the multiple binding group is a group represented by R ² , R ³ and R ⁶ in the general formula of the cellulose derivative are -R, -OC-R, -OCNH-R, -OC-OR, Aromatic group). When R ² , R ^3, and R ⁶ are an aromatic group, the multiple binding group is ether-bonded to the glucose skeleton and contained in the substituent having the above-described glucose skeleton and ether bond. When at least a part of the multiple bonding groups are bonded to the glucose skeleton through an ether bond, change in color tone and change in reflection performance are suppressed in the organic EL display manufactured using the obtained optical film.

Further, when the multiple bonding group is an aromatic group, excellent productivity is achieved. This is because the effect of adjusting the wavelength dispersion by the multiple binding groups is easily exhibited by making the multiple binding groups into an aromatic structure having a large change in birefringence with respect to the wavelength, so that sufficient wavelength dispersion adjustment effect can be obtained even if the degree of substitution is low. This makes it possible to shorten the reaction time when introducing the multiple binding groups into the glucose skeleton, to suppress the influence of the elimination of other substituents, and the stability of production is enhanced. Further, since the degree of substitution of the multiple bonding groups can be made small, it is possible to increase the number of hydroxyl groups per glucose skeleton unit, and consequently to improve the film brittleness by increasing the hydrogen bonding property between the resins .

In this specification, the term "aromatic" refers to a compound defined as an aromatic compound on page 1208 of the Physicochemical Dictionary (Iwanami Shoten), fourth edition. The aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and more preferably an aromatic hydrocarbon group.

The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 10 carbon atoms. Specific examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthryl group, a biphenyl group, a terphenyl group and the like. Of these, a phenyl group, a naphthyl group and a biphenyl group are preferable, and a phenyl group is preferable.

The aromatic heterocyclic group preferably includes at least one of an oxygen atom, a nitrogen atom or a sulfur atom. Examples of such heterocycle include furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole , Oxadiazole, quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, Benzothiazole, benzotriazole, tetrazaine, and the like. Of these, a pyridyl group, a thiophenyl group, a triazinyl group, and a quinolyl group are preferable.

Specific examples of the aromatic group bonded through the glucose skeleton and the ether bond include benzyl ether, 4-phenylbenzyl ether, 4-thiomethylbenzyl ether, 4-methoxybenzyl ether, 2,4,5- , 5-trimethoxybenzyl ether, and the like.

Other examples of the aromatic group bonded by the ether linkage to the glucose skeleton include 2-thienyl ether, 3-thienyl ether, 4-thiazolyl ether, 2-thiazolyl ether, 2-furyl ether, Pyrrolyl ether, 3-imidazolyl ether, 2-triazolyl ether, 1-pyrrolyl ether, 1-imidazolyl ether, Pyridyl ether, 2-pyridyl ether, 2-pyrimidyl ether, 2-quinolyl ether, 2-quinolyl ether, 2- Benzothiazolyl ether, 2-benzothiazolyl ether, 2-benzoxazolyl ether, 2-benzothiazolyl ether, 2-benzothiazolyl ether, 2-benzimidazolyl ether, and the like.

Preferable examples of the aromatic acyl group include benzoyl group, phenylbenzoyl group, 4-methylbenzoyl group, 4-thiomethylbenzoyl group, 4-methoxybenzoyl group, 4-heptylbenzoyl group, A 2,4,5-trimethylbenzoyl group, a 3,4,5-trimethoxybenzoyl group, and a naphthoyl group.

Other examples of the aromatic acyl group include 2-thiophenecarboxylic acid ester, 3-thiophenecarboxylic acid ester, 4-thiazolecarboxylic acid ester, 2-thiazolecarboxylic acid ester, Ester, 3-furancarboxylic acid ester, 3-furancarboxylic acid ester, 4-oxazole carboxylic acid ester, 2-oxazole carboxylic acid ester, Pyrrolecarboxylic acid ester, 3-pyridinecarboxylic acid ester, 2-pyridinecarboxylic acid ester, 3-pyridinecarboxylic acid ester, Pyrimidine carboxylic acid ester, 2-pyridinecarboxylic acid ester, 2-quinolinecarboxylic acid ester, 2-quinoxaline carboxylic acid ester, 4-pyrimidine carboxylic acid ester, Carlsbad Benzoic acid esters, 2-benzofuran carboxylic acid esters, 2-indole carboxylic acid esters, 2-benzoquinolinecarboxylic acid esters, 2-benzoquinolinecarboxylic acid esters, Thiazolecarboxylic acid esters, 2-benzoxazole carboxylic acid esters and 2-benzimidazole carboxylic acid esters.

These aromatic groups may also have a substituent, but it is preferable that they do not have a substituent group containing a carboxyl group (-C (= O) O-). If it contains a carboxyl group, the hydrophilicity increases, and the humidity dependency of optical properties tends to be deteriorated. The aromatic group is preferably an aromatic moiety that is unsubstituted or substituted with an alkyl group or an aryl group.

The cellulose derivative of the present embodiment can be produced by a known method, for example, by referring to the method described in "Cellulose Dictionary", pages 131 to 164 (Asakura Shoten, 2000). Specifically, the cellulose derivative of the present embodiment is obtained by using a cellulose ether in which a part of hydroxyl groups at 2-position, 3-position and 6-position are substituted with an ether group as a raw material and adding an acid chloride or an acid anhydride in the presence of a base such as pyridine To thereby introduce a desired substituent or a desired substituent bonded with an ester.

The substitution degree of a substituent having a glucose skeleton can be determined by ¹ H-NMR or the like using the method described in, for example, Cellulose Communication 6, 73-79 (1999) and Chirality 12 (9), 670-674 Can be determined by &lt; ¹³ &gt; C-NMR.

The weight average molecular weight of the cellulose ether derivative is preferably from 100,000 to 400,000, more preferably from 130,000 to 300,000, and still more preferably from 150,000 to 250,000. When the molecular weight is more than 400,000, not only the solubility in the solvent is lowered but also the viscosity of the obtained solution becomes too high, which is not suitable for the solvent casting method, and the thermoforming becomes difficult and the transparency of the film is lowered There is a tendency to occur. On the other hand, when the molecular weight is less than 100,000, the mechanical strength of the obtained film tends to be lowered.

As the cellulose ether derivative, a cellulose ether derivative prepared from a single raw material may be used, or two or more kinds of cellulose ether derivatives different in raw materials may be used in combination.

(Silica-based fine particles)

The optical film of the present embodiment contains silica-based fine particles as a matting agent. Examples of such silica-based fine particles include silicon dioxide, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate and magnesium silicate. Of these, silicon dioxide is preferable from the viewpoint of suppressing an increase in haze of the obtained film. The silicon dioxide fine particles preferably have an average primary particle diameter of 1 to 20 nm and an apparent specific gravity of 70 g / L or more. Among them, it is preferable that the average primary particle diameter is 5 to 16 nm because the haze of the obtained optical film can be satisfactorily lowered. It is preferable that the apparent specific gravity is 90 to 200 g / L, more preferably 100 to 200 g / L. The larger the value of the apparent specific gravity is, the better the dispersion liquid with a high concentration can be adjusted and the haze and agglomerates are improved.

Specific examples of the fine particles of silicon dioxide include commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (manufactured by Nippon Aerosil Co., Ltd.). Above all, Aerosil 200V and Aerosil R972V are preferable because they have an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more, and the effect of lowering the coefficient of friction while keeping the haze of the resulting film low .

The silica-based fine particles usually form secondary particles having an average particle diameter of 0.05 to 2.0 占 퐉. These secondary particles exist as agglomerates of primary particles in the optical film and form irregularities of 0.05 to 2.0 탆 on the surface of the optical film. The average secondary particle diameter is preferably 0.05 to 1.0 占 퐉, more preferably 0.1 to 0.7 占 퐉, and even more preferably 0.1 to 0.4 占 퐉. The primary particle diameter and the secondary particle diameter can be calculated, for example, by observing fine particles in an optical film with a scanning electron microscope and making the diameter of a circle circumscribing the particles a particle size. At this time, it is possible to adopt a method in which 200 particles are observed by moving the place and an average particle size is obtained with the average value.

The method for producing the silica-based fine particles is not particularly limited, and for example, there is a method of preparing a fine particle dispersion in which a solvent and fine particles are mixed and stirred, and mixing the fine particle dispersion with a cellulose derivative dope prepared separately using an inline mixer Can be adopted.

When hydrophobic treatment is performed on the surface of the silica-based fine particles, when another hydrophobic additive is added, the additive is adsorbed on the surface of the fine particles, and aggregates of the additive containing nuclei are easily generated. Therefore, it is preferable that a hydrophilic additive is mixed with a fine particle dispersion in advance, and then a hydrophobic additive is mixed to suppress aggregation of the additive on the surface of the silica based fine particle. As a result, the haze of the obtained film is lowered, and when the circularly polarizing plate employing such a film is incorporated in the organic EL display, light leakage in black display can be suppressed.

When the fine particles of silicon dioxide are mixed with a solvent or the like and dispersed, the concentration of silicon dioxide is preferably from 5 to 30 mass%, more preferably from 10 to 25 mass%, still more preferably from 15 to 20 mass%. The final addition amount of the matting agent in the dope solution of the cellulose derivative is preferably in the range of 0.001 to 1.0 mass%, more preferably in the range of 0.005 to 0.5 mass%, further preferably in the range of 0.01 to 0.1 mass%.

(Other additives)

In addition to the above-mentioned silica-based fine particles, the optical film of the present embodiment may contain various additive agents exemplified below as other additives. Examples of such additives include deterioration inhibitors, ultraviolet absorbers, matting agents other than silica-based fine particles, plasticizers, and the like.

(Deterioration inhibitor)

The optical film of the present embodiment may contain, for example, a deterioration inhibitor such as an antioxidant, a peroxide dissolution inhibitor, a radical polymerization inhibitor, a metal deactivator, an acid capturing agent, or an amine. Examples of the deterioration inhibitor include those disclosed in JP-A-3-199201, JP-A-5-197073, JP-A-5-194789, JP-A-5-271471, 6-107854 can be used. Specifically, butylated hydroxytoluene (BHT) and tribenzylamine (TBA) can be used. The content of the deterioration inhibitor is preferably 0.01 to 1% by mass, more preferably 0.01 to 0.2% by mass, of the cellulose solution (dope) from the viewpoint of suppressing bleeding out (smearing) Do.

(Ultraviolet absorber)

The optical film of this embodiment may contain an ultraviolet absorber. Examples of the ultraviolet absorber include oxybenzophenone compounds, benzotriazole compounds, salicylic ester compounds, benzophenone compounds, cyanoacrylate compounds, and nickel complex salt compounds. Among them, a benzotriazole-based compound having less coloration is preferable. The ultraviolet absorber described in JP-A-10-182621, JP-A-8-337574, and JP-A-6-148430 are preferably used. When the optical film of the present embodiment is used as a protective film of a polarizing plate in addition to a retardation film, ultraviolet absorbers preferably have excellent ultraviolet ray absorbing ability at a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the polarizer and the organic EL element, From the viewpoint of the display property of the EL element, it is preferable that the EL element has a characteristic that absorption of visible light with a wavelength of 400 nm or more is small.

Examples of the benzotriazole-based compound include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'- Triazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) benzotriazole, 2- (2'- -5-chlorobenzotriazole, 2- [2'-hydroxy-3'- (3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2 , 2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] butylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (straight chain and branched dodecyl) 3- [3-t-butyl-4-hydroxyphenyl] propionate and 2-ethylhexyl-3- [ Hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate. TINUVIN) 171, TINUVIN) 326, TINUVIN) 328 (manufactured by BASF Japan Co., Ltd.) as commercial products, Is preferably used.

The addition amount of the ultraviolet absorber is preferably in the range of 0.1 to 5.0 mass%, more preferably in the range of 0.5 to 5.0 mass% with respect to the cellulose derivative.

(A matting agent other than silica-based fine particles)

The optical film of the present embodiment may contain a matting agent other than the above silica-based fine particles. Examples of the matting agent include titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate and calcium phosphate. Since the particle size, apparent specific gravity, production method, and addition amount of these matting agents are the same as those of the silica-based fine particles, their explanation is omitted.

(Plasticizer)

Various plasticizers can be used together with the optical film of the present embodiment for the purpose of improving fluidity and flexibility of the composition. Examples of the plasticizer include polyvalent alcohol ester plasticizers, glycolate plasticizers, phthalate ester plasticizers, citrate ester plasticizers, fatty acid ester plasticizers, phosphate ester plasticizers, polycarboxylic ester plasticizers, acrylic plasticizers, and the like. . Depending on the application, these plasticizers may be selected or used in combination for a wide range of applications.

<Production method of optical film>

Next, a manufacturing method of the optical film will be described. The optical film of the present embodiment can be formed by a known method. Hereinafter, representative solution casting methods and melt casting methods will be described.

(Solution softening method)

The optical film of the present embodiment can be produced by a solution casting method. In the solution casting method, a step of producing a dope by heating and dissolving a thermoplastic resin such as a cellulose derivative and an additive (containing silica-based fine particles) in an organic solvent, a step of softening the prepared dope on a belt- A step of drying the flexible dope as a web, a step of peeling off the metal support, a step of stretching or shrinking the peeled web, a step of drying, a step of winding the finished film, and the like.

(Dope preparation step)

In the dope-preparing step, the cellulose derivative in the dope is preferable because a higher concentration can reduce the drying load after being softened to the metal support. However, if the concentration of the cellulose derivative is too high, the load during filtration increases, It falls out. Therefore, the concentrations compatible therewith are preferably within a range from 10 mass% to 35 mass%, and more preferably within a range from 15 mass% to 30 mass%.

(Flexible process)

The metal support used in the casting (casting) process preferably has a mirror-finished surface, and a stainless steel belt or a casting finish drum is preferably used.

The width of the cast is preferably in the range of 1 m to 4 m. The surface temperature of the metal support of the softening process is suitably set at a temperature range of -50 DEG C or higher and a temperature at which the solvent does not foam by boiling. The higher the temperature, the higher the drying speed of the web. However, if the temperature is too high, the web may foam and the planarity may deteriorate. The surface temperature of the metal support is preferably 0 ° C or higher and 100 ° C or lower, more preferably 5 ° C or higher and 30 ° C or lower. Further, the web can be gelled by cooling to peel off the drum in a state containing a large amount of residual solvent. The method of controlling the temperature of the metal support is not particularly limited, and a method of blowing warm air or cold air or a method of bringing hot water into contact with the back surface of the metal support may be employed. The method of using hot water is preferable because the time required until the temperature of the metal support becomes constant is short since heat transfer is performed efficiently. As a method of using warm air, in consideration of the temperature drop of the web due to the latent heat of evaporation of the solvent, wind at a temperature higher than a desired temperature may be used while preventing the foaming while using warm air above the boiling point of the solvent. In particular, it is preferable to change the temperature of the support body and the temperature of the drying wind during the period from the softening to the peeling, and to perform the drying efficiently.

The amount of the residual solvent when peeling the web from the metal support is preferably in the range of 10 mass% to 150 mass%, more preferably 20 mass% or more and 40 mass% or less or 60 mass% or less, Or more and 130 mass% or less, and more preferably 20 mass% or more and 30 mass% or less or 70 mass% or more and 120 mass% or less.

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

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

Wherein M is the mass of the sample taken at any point in time during or after the production of the web or film and N is the mass of the sample taken at any point in the web or film during or after manufacture at 115 ° C for 1 hour Mass after heating)

(Drying step)

Examples of the drying method employed in the drying process include those disclosed in U.S. Patent Nos. 2,336,310, 2,367,603, 2,492,078, 2,492,977, 2,492,978, 2,607,704, 2,739,069 and 2,739,070 Japanese Patent Publication Nos. 45-4554, 49-5614, 60-176834, 60-203430, and 60-203430, each of the specifications of U.S. Patent Nos. 640,731 and 736,892, There is a method described in JP-A-62-115035. Drying on the drum or band can be performed by blowing an inert gas such as air or nitrogen to the web.

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

In the drying step, a roller drying method is employed, for example, a method in which webs are alternately passed through a plurality of rollers arranged vertically, or a method in which a web is conveyed while being dried by a tenter method is employed.

(Drawing step)

As described above, the optical film of this embodiment preferably has an in-plane retardation Ro ₅₅₀ measured at a wavelength of 550 nm of 120 nm or more and 160 nm or less. This phase difference can be imparted by stretching the film.

The stretching method is not particularly limited. For example, there are a method in which a peripheral speed difference is generated in a plurality of rollers and a longitudinal direction is elongated using a roller peripheral speed difference therebetween, a method in which both ends of the web are fixed with clips or pins, A method of stretching in the transverse direction by extending in the transverse direction or a method of stretching in the transverse direction in the transverse direction or a method of stretching in both the transverse direction and the transverse direction in the transverse direction can be used alone or in combination . That is, even if stretched in the transverse direction with respect to the film-forming direction, stretching in the transverse direction may be performed in both directions, and in the case of stretching in both directions, simultaneous stretching or sequential stretching may be employed. In the case of the so-called tenter system, it is preferable to drive the clip portion by the linear drive system, since smooth drawing can be performed and the risk of breakage can be reduced.

In the stretching step, the stretching is usually performed in the width direction (TD direction) and shrinking in the carrying direction (MD direction). However, when shrinking, when conveying in the oblique direction, the main chain direction tends to be aligned, . The shrinkage ratio can be determined according to the angle at which the substrate is transported.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram for explaining the contraction magnification in oblique stretching. Fig. In Fig. 1, when the cellulose acylate film F is obliquely stretched in the direction of the reference numeral 112, the long axis M _{1 in the} conveying direction is deflected and contracted to M ₂ .

At this time, the shrinkage percentage (%) is

Shrinkage percentage (%) = ((M ₁ -M ₂ ) / M ₁ ) × 100

. If the bending angle is?

M ₂ = M ₁ sin (? -?)

And the shrinkage rate is

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

.

In Fig. 1, reference numeral 111 denotes a stretching direction, 113 denotes a transporting direction (MD direction), and 114 denotes a slow axis.

Considering the productivity of the circularly polarizing plate, it is preferable that the optical film of the present embodiment has an orientation angle of 45 占 占 2 with respect to the conveying direction, since it is possible to join the polarizing film to the roll, roll and roll.

(Elongation by a warp stretching device)

Next, the oblique stretching method of stretching in the 45 占 direction will be further described. In the method for producing an optical film of the present embodiment, it is preferable to use an oblique stretching device as a method for imparting the orientation of the oblique direction to the stretched optical film.

As the oblique stretching device applicable to the present embodiment, it is possible to freely set the orientation angle of the film by variously changing the rail pattern, to align the orientation axis of the film in the film width direction uniformly and horizontally, And is preferably a film stretching device capable of controlling film thickness and retardation with high precision.

Fig. 2 is a schematic view showing an example of a rail pattern of a warp stretching device applicable to manufacture of the optical film of the present embodiment. The drawing shown here is only an example, and the drawing apparatus applicable in the present embodiment is not limited to this.

In general, in the warp stretching apparatus, as shown in Fig. 2, the unwinding direction D1 of the long film fabric is different from the winding direction D2 of the stretched film after stretching, and forms the unwinding angle? I. The unwinding angle &amp;thetas; i is in a range exceeding 0 DEG and less than 90 DEG, and can be arbitrarily set to a desired angle.

Both ends of the long film fabric are gripped by the right and left tappets (tenters) at the entrance of the oblique stretching device (position A in the figure), and travel along with the running of the waveguide. At the entrance of the oblique stretching device (position A in the drawing), the left and right wave fringes Ci and Co opposed to each other in the direction substantially perpendicular to the film advancing direction (unwinding direction D1) ), And releases the gripped film at the position (B position in the drawing) at the time of completion of the stretching.

At this time, as the left and right wave earths opposed to each other at the entrance of the oblique extension apparatus (position A in the figure) travel on the right and left asymmetrical rails (Ri, Ro), the wave earth (Ci) (Co) traveling on the road.

That is, at the entrance of the oblique-stretching device (the gripping start position by the wave-like earth of the film) A, the wave-like earths Ci and Co which were opposed to each other in the direction substantially perpendicular to the unwinding direction D1 of the film, The straight line connecting the waveguides Ci and Co is inclined only by an angle? L with respect to a direction substantially perpendicular to the winding direction D2 of the film.

According to the above method, the film material is obliquely stretched so that the alignment angle becomes? L, and an optical film can be obtained. The term &quot; substantially perpendicular &quot;

More specifically, in the manufacturing method of the present embodiment, it is preferable that oblique stretching is performed using the above-described warp stretchable stretching apparatus. This stretching apparatus can heat the film raw material to an arbitrary temperature capable of stretching and obliquely stretch. This stretching device is provided with a heating zone, a pair of right and left rails on which a wave earth for transporting the film travels, and a plurality of wave earths running on the rails. Both ends of the film sequentially fed to the inlet of the stretching device are gripped by gripping holes to guide the film in the heating zone and the film is opened from the waveguide at the outlet of the stretching device. The film opened from the wave earth is wound on the winding core. Each of the pair of rails has a continuous trajectory of an endless shape, and the waveguide which opens the grip of the film at the outlet of the stretching device travels on the outside and returns to the subsequent inlet portion.

Further, the rail pattern of the stretching device has a left-right asymmetric shape, and the rail pattern can be adjusted manually or automatically depending on an orientation angle (?) Given to a long stretched film to be produced, a stretching magnification or the like. In the oblique drawing apparatus used in the manufacturing method of the present embodiment, it is preferable that the position of each rail portion and the rail connecting portion can be freely set and the rail pattern can be arbitrarily changed (circle in Fig. 2 is an example of the connecting portion).

In the present embodiment, the wave earth of the elongating apparatus is kept at a constant distance from the wave earth before and behind the vehicle, and travels at a constant speed. The running speed of the breaking earth can be appropriately selected, but is usually 1 to 100 m / min. The running speed difference of the pair of left and right wave earths is usually 1% or less, preferably 0.5% or less, more preferably 0.1% or less of the running speed. This is because, if there is a difference in the traveling speed of the film from the exit of the stretching device to the left and right, wrinkles or gathering occurs at the outlet of the stretching device, and therefore the velocity difference between the left and right wave strips is required to be substantially the same. In a general stretching device or the like, there is a speed deviation occurring on the order of seconds or less depending on the sawing period of the sprocket for driving the chain, the frequency of the drive motor, etc., and often causes a deviation of several percent. This does not apply to the speed difference.

In the stretching apparatus according to the present embodiment, a large bending rate is often required in the rail for regulating the trajectory of the waveguide, particularly at a position where the conveyance of the film becomes oblique. In order to avoid interference between waveguides due to abrupt bending, or local concentration of stress, it is preferable to make the locus of the waveguide curved at the bent portion.

In the present embodiment, the long film fabric is held at both ends of the entrance of the warp and stretch device (position A in the figure) by the left and right waveguides, and travels along with the running of the waveguide. At the entrance of the oblique stretching device (position A in the drawing), the left and right waveguides opposed to each other in the direction substantially perpendicular to the film advancing direction (unwinding direction D1) travel on left and right asymmetrical rail images, , And a heating zone having a heat fixing zone.

The preheating zone refers to a section in which a gap between waveguides holding both ends of a heating zone inlet portion is maintained at a constant interval.

The stretching zone refers to a section from a gap between waveguides holding both ends to a predetermined gap. In the stretching zone, the oblique stretching as described above is performed, but stretching in the longitudinal direction or the transverse direction may be performed before and after oblique stretching, if necessary. In the case of oblique stretching, shrinkage in the MD direction (the direction of the advancing axis), which is perpendicular to the slow axis at the time of bending, is accompanied.

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

The temperature of each zone is preferably in the range of Tg to Tg + 30 占 폚 in the preheating zone, in the range of Tg to Tg + 30 占 폚 in the stretching zone, and in the range of Tg-30 占 폚 to 30 占 폚 in the cooling zone to the glass transition temperature Tg of the cellulose derivative. Tg. &Lt; / RTI &gt;

Further, in order to control the thickness unevenness in the width direction, a temperature difference may be generated in the width direction in the stretching zone. In order to cause a temperature difference in the width direction in the stretching zone, there are a method of adjusting the opening degree of the nozzle for sending the warm air into the constant temperature chamber to make a difference in the width direction, a method of heating and controlling the heater in the width direction Can be used.

The length of the preheating zone, the stretch zone, and the heat fixing zone can be appropriately selected, the length of the preheating zone is usually in the range of 100 to 150%, and the length of the heat fixing zone is usually 50 to 100% Within the range.

The draw ratio (W / W0) in the drawing step is preferably in the range of 1.3 to 3.0, more preferably in the range of 1.5 to 2.8. When the stretching magnification falls within this range, thickness non-uniformity in the width direction can be reduced. In the stretching zone of the oblique stretching device, by causing a difference in stretching temperature in the width direction, the thickness non-uniformity in the width direction can be further improved. Wo is the film width before stretching, and W is the film width after stretching.

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

Fig. 3 is a schematic view showing a method for producing an optical film of the present embodiment (an example in which a long film is unwound from a roll and then obliquely stretched), and a pattern for loosening a long film material wound once in a roll shape and obliquely stretching . Fig. 4 is a schematic view showing a method for producing an optical film of the present embodiment (an example in which a continuous film is obliquely stretched without winding a long film material), and a pattern for continuously obliquely stretching the film without winding the long film material .

3 and 4, reference numeral 15 denotes an oblique stretching device, reference numeral 16 denotes a film feeding device, reference numeral 17 denotes a transport direction changing device, 18 denotes a winding device, and 19 Shows a film-forming apparatus. In each figure, the same reference numerals may be omitted.

The film feeding device 16 is slidable and slidable so as to allow the film to be fed at an angle with respect to the entrance of the oblique stretching device or is slidable, It is preferable to be able to send the data. 3 (a) to 3 (c) show a pattern in which the arrangement of the film delivery device 16 and the transport direction changing device 17 are changed, respectively. 4 (a) and 4 (b) show a pattern in which the film formed by the film-forming apparatus 19 is directly loosened to the stretching apparatus. By making the film feeding device 16 and the conveying direction changing device 17 have such a configuration, the entire width of the manufacturing device can be made narrower, and besides the position and angle of the film can be finely controlled And it is possible to obtain a long stretched film having a small deviation of the thickness and the optical value of the film. In addition, by making the film feeding device 16 and the conveying direction changing device 17 movable, it is possible to effectively prevent the sticking of the left and right clips from sticking to the film.

The winding device 18 is arranged so that the film is pulled out at a predetermined angle with respect to the exit of the warp stretcher device, whereby the pulling out position and angle of the film can be finely controlled. As a result, a long stretched film having a small deviation in thickness and optical value of the film is obtained. As a result, the occurrence of wrinkles of the film can be effectively prevented and the winding-up property of the film is improved, so that the film can be wound in a long length. In the present embodiment, the film pulling tension T (N / m) after stretching is preferably adjusted within a range of 100 N / m <T <300 N / m, preferably 150 N / m <T <250 N / m.

(Melt forming method)

The optical film may be formed by a melt film forming method. The melt film-forming method is a molding method in which a composition containing a cellulose derivative or the like is heated and melted to a temperature at which fluidity is exhibited, and then a melt containing a flowable cellulose derivative is softened.

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

The plurality of raw materials used in the melt extrusion method are usually kneaded in advance and pelletized. The pelletization can be carried out by a known method. For example, a dry cellulose derivative or an additive is fed to an extruder through a feeder, kneaded using a uniaxial or biaxial extruder, extruded from a die in a strand shape, And cutting it.

The additives may be mixed before being fed to the extruder, or they may be fed from individual feeders. In addition, small amounts of additives such as fine particles and antioxidants are preferably mixed in advance in order to uniformly mix them.

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

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

The pellets are extruded using a uniaxial or biaxial extruder. The extruded pellets are melted at a temperature of 200 DEG C or more and 300 DEG C or less, filtered with a filter such as a leaf disc type filter, And the film is nipped with the cooling roller and the elastic touch roller, and solidified on the cooling roller.

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

The extrusion flow rate is preferably stably performed by introducing a gear pump. In addition, a stainless steel fiber sintered filter is preferably used as the filter used for removing the foreign matter. The stainless steel fiber sintering filter is formed by integrally forming a stainless steel fiber body in a state where the fibers are intricately intertwined with each other, compressing the sintered portions, and sintering the contact portions. The filtration accuracy can be adjusted by changing the density by the thickness of the fibers and the amount of compression.

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

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

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

The film thus obtained can be subjected to stretching and shrinking treatment by a stretching operation after passing through a process in contact with a cooling roller. As the method of stretching and shrinking, a known roller stretching device or a warp stretching device as described above can be preferably used. It is preferable that the stretching temperature is usually carried out within a temperature range of not less than Tg (Tg + 60 DEG C) of the resin constituting the film.

Prior to winding, knurling (embossing) may be performed at both ends in order to slit the end portion so as to have a width of the product, or to prevent adhesion and scratching during winding. A method of knurling can be performed by heating or pressing a metal ring having a concavo-convex pattern on its side surface. Further, the clip holding portions at both ends of the film are usually cut and reused because the film is deformed and can not be used as a product.

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

The angle between the in-plane slow axis of the optical film and the transmission axis of the polarizer is preferably in a range of 41 to 49 degrees, more preferably in a range of 42 to 48 degrees, more preferably in a range of 43 to 47 Deg.] Or less, and particularly preferably in the range of 44 [deg.] To 46 [deg.].

<Circular Polarizer>

The circular polarizer of the present embodiment is produced by cutting a long protective film, a long polarizer and a long roll having the long optical film (phase difference film) in this order. Since the circularly polarizing plate is produced by using the above optical film, it is possible to exhibit the effect of shielding the mirror reflection of the metal electrode of the organic EL element at the entire wavelength of visible light by applying it to an organic EL display or the like to be described later. As a result, the projection at the time of observation can be prevented, and the black color expression can be improved.

It is preferable that the circularly polarizing plate of this embodiment has an ultraviolet ray absorbing function. When the protective film on the viewer side has an ultraviolet ray absorbing function, a protective effect against ultraviolet rays can be exhibited on both the polarizer and the organic EL element. In addition, when the retarder film on the light-emitting body side has the ultraviolet ray absorbing function, deterioration of the organic EL element can be suppressed more in the case of using the retardation film on the light-

In addition, the circular polarizer of this embodiment uses the retardation film in which the angle of the slow axis (that is, the orientation angle [theta]) is adjusted to be substantially 45 [deg.] With respect to the longitudinal direction to form the adhesive layer And the polarizer and the retardation film can be bonded to each other. Concretely, it is possible to combine the step of bonding the polarizer and the retardation film during the drying step or after the drying step, which is performed after the step of preparing the polarizer by stretching the polarizing film, And can be connected in a consistent manufacturing line to the next process by winding in rolls after bonding. Further, when the polarizer and the retardation film are bonded to each other, the protective film can be supplied in a roll state at the same time and can be continuously bonded. From the viewpoints of performance and production efficiency, it is preferable to simultaneously bond the polarizing film to the retardation film and the protective film. That is, after the step of preparing the polarizer by stretching the polarizing film is finished, the protective film and the retardation film are bonded to both sides of the circular polarizer in the drying step or the drying step which is carried out subsequently, . &Lt; / RTI &gt;

In the circularly polarizing plate of the present embodiment, it is preferable that the polarizer is sandwiched between the retardation film and the protective film, and a cured layer is preferably laminated on the viewer side of the protective film.

(Protective film)

As the protective film to be used for the circularly polarizing plate, a cellulose ester-containing film is suitably used, and for example, a commercially available cellulose ester film (for example, Konica Minolta Tac KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR , KC4FR, KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA, KC6UAKC, 2UAH, KC4UAH, KC6UAH, or above, Konica Minolta Co., Ltd., Fujixt T40UZ, T80UZ, Fujitac TD80UL, Fujitac TD60UL, Fujitac TD40UL, Fujitac R02, Fujitac R06, manufactured by Fuji Film Co., Ltd.) are preferably used. The thickness of the protective film is not particularly limited and may be about 10 to 200 占 퐉, preferably 10 to 100 占 퐉, and more preferably 10 to 70 占 퐉.

(Polarizer)

 The polarizer is a device which passes only light of a polarization plane in a certain direction, and for example, there is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film includes a polyvinyl alcohol film stained with iodine and a dichroic dye stained.

The polarizer can be produced by uniaxially stretching a polyvinyl alcohol film followed by dyeing, or by dyeing a polyvinyl alcohol film, followed by uniaxial stretching, preferably by durability treatment with a boron compound. The film thickness of the polarizer is preferably in the range of 5 to 30 mu m, more preferably in the range of 5 to 15 mu m.

As the polyvinyl alcohol film, the content of the ethylene unit is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, the degree of saponification is 99.0 to 99.99 mol % Of ethylene-modified polyvinyl alcohol is preferably used. Further, it can be produced by the method described in Japanese Patent Application Laid-Open Nos. H11-100161, H46-12055, and H4804589.

&Lt; Organic Electroluminescence Display Device (Organic EL Display) >

The organic EL display of the present embodiment is manufactured by using the circular polarizer. More specifically, the organic EL display of the present embodiment includes a circularly polarizing plate using the retardation film and an organic EL element. The screen size of the organic EL display is not particularly limited, and may be 20 inches or more.

5 is a schematic view of the organic EL display configuration of the present embodiment. The configuration of the organic EL display 100 shown in Fig. 5 is an example, and the configuration of the organic EL display of the present embodiment is not limited at all.

5, a metal electrode 2, a TFT (thin film transistor) 3, an organic light emitting layer 4, a transparent electrode (ITO (indium oxide The polarizer 10 is placed on the organic EL element 200 having the organic EL element 200 having the insulating layer 6, the sealing layer 7 and the film 8 (not shown) And the circular polarizer 300 sandwiched by the protective film 11 are provided to constitute the organic EL display 100. The protective film 11 is preferably laminated with a cured layer 12. The cured layer 12 not only prevents surface scratches of the organic EL display but also has an effect of preventing warping by the circular polarizer. The antireflection layer 13 may be provided on the cured layer. The thickness of the organic EL device itself is about 1 mu m.

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

In the organic EL display, holes and electrons are injected into the organic light emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by the recombination of the holes and the electrons excites the fluorescent substance, The light is emitted on the principle that light is emitted. The recombination mechanism is the same as that of a general diode, and the current and the light emission intensity exhibit strong nonlinearity accompanied by rectification with respect to the applied voltage.

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

The circular polarizer having the above retardation film can be applied to an organic EL display including a large screen having a screen size of 20 inches or more, that is, a diagonal distance of 50.8 cm or more.

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

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

The retardation film and the polarizing plate have the effect of making the mirror surface of the metal electrode not visible from the outside due to the polarizing action because the polarizing plate has the function of polarizing the light reflected from the metal electrode after being incident from the outside. Particularly, when the phase difference film is constituted by a quarter phase difference film and the angle formed by the polarization direction between the polarizer and the retardation film is adjusted to? / 4, the mirror surface of the metal electrode can be completely shielded.

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

The circularly polarized light is transmitted through the transparent substrate, the transparent electrode and the organic thin film, reflected by the metal electrode, again transmitted through the organic thin film, the transparent electrode and the transparent substrate, and becomes linearly polarized again in the retardation film. Since the linearly polarized light is orthogonal to the polarization direction of the polarizing plate, it can not transmit through the polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded. Therefore, according to the organic EL display of the present embodiment, reflection of external light is suppressed, and the spot contrast and black reproducibility are excellent.

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

An aspect of the present invention relates to a cellulose acylate film comprising a cellulose derivative and silica-based fine particles, wherein an angle formed by the long direction and the slow axis is 40 to 50 DEG, an in- plane retardation Ro ₅₅₀ at a wavelength of 550 nm is 120 nm or more and 160 nm or less, (1) to (3).

1.8 &lt; / = (One)

0.3? X _ES? 1.5 ... (2)

0.3? X _ETH ? (3)

X _ES is the average degree of ester substitution of the cellulose derivative, X _ETH is the ether average degree of substitution of the cellulose derivative, and Y is the total degree of substitution of the cellulose derivative.

In the long optical film according to one embodiment of the present invention, the retardation fluctuation caused by the water coordination to the cellulose derivative is suppressed by adjusting the substituent ratio of the cellulose derivative to be used, not by adding the additive. As a result, changes in optical performance (color performance, reflection characteristics) against humidity fluctuations are suppressed in the obtained optical film. Further, since the added matting agent (silica-based fine particles) hardly flocculate, the effect of suppressing the rise of haze by the matting agent can be sufficiently obtained. Further, the long optical film of the present invention exhibits excellent brittleness as well as being able to impart a phase difference of substantially? / 4 to visible light in a broad band of light.

Moreover, in the long optical film, is preferably not more than the ratio of the retardation Ro in the plane ₄₅₀ within a wavelength 450nm for _{Ro 550 (Ro 450 / Ro 550} ) is more than 0.70 or 0.98. As a result, excellent reverse wavelength dispersion characteristics are exhibited.

In the long optical film, the cellulose derivative preferably has a multiple binding group having an absorption maximum at a wavelength of 220 nm or more and 350 nm or less and an average degree of substitution of the multi-binding group in the cellulose derivative is 0.3 or more and 0.7 or less Do. As a result, the reverse wavelength dispersion characteristic can be further improved.

Further, in the long optical film, it is preferable that the film thickness is in the range of 20 to 60 mu m. As a result, the desired in-plane retardation value Ro can be easily expressed.

Another embodiment of the present invention is a circularly polarizing plate in which the long optical film and a polarizer are bonded.

According to such a configuration, by applying to an organic EL display or the like, it is possible to exhibit an effect of shielding reflection of the mirror surface of the metal electrode of the organic EL element at the entire wavelength of visible light. As a result, the projection at the time of observation can be prevented, and the black color expression can be improved.

According to another aspect of the present invention, there is provided an organic electro luminescence display device having the circular polarizer.

According to such a configuration, reflection of external light is suppressed, and spot contrast and black reproducibility are excellent.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a long optical film which exhibits a sufficient retardation, exhibits a retardation in retardation due to humidity fluctuation, is excellent in adhesiveness with a polarizer and in embrittlement, A polarizing plate and an organic electro luminescence display device can be provided.

Example

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. In the examples, "parts" or "%" are used, and unless otherwise specified, "parts by mass" or "% by mass" shall be used. In addition, the degree of substitution and the number of substituents shown below all represent an average value.

&Lt; Example 1 >

The retardation film (1) was produced by the following method.

(Synthesis of Cellulose Derivative 1)

(Step 1: Synthesis of cellulose ether)

First, 140 g of a 60% sodium hydroxide solution was added to 100 g of a pulp (a cellulose content of 98.4%) of the all-hydrolysis kraft process. Subsequently, 400 g of bromobutane was added, and the mixture was maintained in a temperature range of 0 to 5 캜 for about 1 hour while stirring, followed by heating at 30 to 40 캜 for 6 hours. The contents were filtered off, the precipitate was removed, and hot water was added thereto. Neutralized with a 1% aqueous phosphoric acid solution, and then added dropwise to acetone to precipitate the reaction product. The reaction mixture was separated by filtration, washed repeatedly with acetone / water (9: 1) several times, and vacuum dried at 60 ° C to obtain butylcellulose. The degree of substitution (MS) of the product by bromobutane was 1.1 as a result of NMR measurement, and this was regarded as cellulose ether.

(Second step: introduction of acetyl group into cellulose ether)

To a 3 L three-necked flask equipped with a mechanical stirrer, a thermometer, a cooling tube and a dropping funnel, 200 g of the cellulose ether obtained in the first step and 2000 mL of acetone were added and stirred at room temperature. 350 g of acetyl chloride was slowly added dropwise thereto, and the mixture was stirred at 50 DEG C for 8 hours. After the reaction, the reaction solution was allowed to cool to return to room temperature, and the reaction solution was poured into 20 L of methanol with vigorous stirring, and a white solid precipitated. The white solid was filtered off by suction filtration and washed three times with a large amount of methanol. The obtained white solid was dried at 60 캜 overnight, and then vacuum-dried at 90 캜 for 6 hours to obtain cellulose derivative 1. The degree of substitution of the substituent in the glucose skeleton of the obtained cellulose derivative 1 was determined by ¹ H-NMR and the degree of substitution by the method described in Cellulose Communication 6, 73-79 (1999) and Chirality 12 (9), 670-674 ¹³ C-NMR, and the average value thereof was determined. As a result, the number of substituents of the butoxy group, which is a substituent having an ether bond, was 2.1, the number of substituents of the acetyl group was 0.3, and the degree of substitution was 2.4.

(Production of the retardation film 1)

(Preparation of fine particle dispersion)

Fine particles (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass

Ethanol 89 parts by mass

The mixture was stirred in a dissolver for 50 minutes, and then dispersed using a Manton-Gaulin dispersing machine to prepare a fine particle dispersion.

(Production of fine particle addition liquid 1)

50 parts by mass of dimethyl chloride was put into the dissolution tank, and 50 parts by mass of the prepared fine particle dispersion was added slowly while sufficiently stirring the dimethyl chloride. Further, dispersion was carried out in the attritor so that the particle diameter of the secondary particles became a predetermined size. This was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle addition liquid 1.

(Preparation of Dope)

First, dimethyl chloride and ethanol shown below were added to a pressurization-dissolving tank. The synthesized cellulose derivative 1 was added to a pressurized dissolution tank containing an organic solvent while stirring. This was heated and completely dissolved while stirring. Subsequently, after the particulate additive liquid 1 was added, the mixture was added to a solution of Azumi Co., Ltd., manufactured by Azumi Co., Ltd. 244 &lt; / RTI &gt; to prepare a dope.

<Composition of Dope>

Dimethyl chloride 340 parts by mass

64 parts by mass of ethanol

Cellulose derivative 1100 parts by mass

Particulate matter added liquid 1 2 parts by mass

(Film forming)

The prepared dope was cast (cast) on a stainless steel belt support, and then the film was peeled off on a stainless steel belt support. The peeled raw film was uniaxially stretched only in the transverse direction (TD direction) by using a stretching device while heating, and the conveying tension was adjusted so as not to shrink in the conveying direction (MD direction). Subsequently, drying was terminated while conveying the drying zone through a plurality of rollers to prepare a roll-shaped textile film.

(Drawing step)

The raw film was stretched in an oblique direction so that the optical slow axis of the film was 45 DEG with respect to the conveying direction by using an oblique stretching device including the constitution shown in Fig. 2 to produce a roll-shaped retardation film 1. Fig. The drawing conditions were such that the film in-plane retardation Ro ₅₅₀ measured at a light wavelength of 550 nm was 138 nm, the film thickness was 50 탆, and Ro ₄₅₀ / Ro ₅₅₀ was 0.9, and the film thickness, stretching temperature and width direction ) And the transport direction (MD direction) were appropriately adjusted.

In addition, Ro ₅₅₀ and Ro ₄₅₀ / Ro ₅₅₀ were measured for in-plane retardation Ro ₄₅₀ at a wavelength of 450 nm and 550 nm using an Axoscan manufactured by Axometrics under conditions of 23 ° C and 55% RH, Ro ₅₅₀ was measured, and Ro ₄₅₀ / Ro ₅₅₀ was calculated.

&Lt; Comparative Examples 1 to 6, Example 2 >

(Synthesis of cellulose derivatives 2 to 8)

In the synthesis of the cellulose derivative 1, the proportions of the respective constituent materials and the reaction conditions in the first step to the second step were appropriately selected and synthesized to be the substituent group structure of the glucose skeleton shown in Table 1, and the cellulose derivatives 1 to 8 .

(Preparation of retardation films 2 to 8)

In the production of the retardation film 1, the retardation films 2 to 8 were produced in the same manner as above except that cellulose derivatives 2 to 8 were used instead of the cellulose derivative 1. The stretching conditions were such that the retardation value Ro _{550 in} the film plane measured at a light wavelength of 550 nm was 140 nm, the film thickness was 50 μm, and the Ro ₄₅₀ / Ro ₅₅₀ was the value described in Table 1. The film thickness, And the draw magnifications in the width direction (TD direction) and the conveying direction (MD direction) were appropriately adjusted.

&Lt; Example 3 >

(Synthesis of cellulose derivative 9)

(First step)

A cellulose ether was prepared in the same manner as in Example 1.

(Second Step)

To a 3 L three-necked flask equipped with a mechanical stirrer, a thermometer, a cooling tube and a dropping funnel, 200 g of the cellulose ether obtained in the first step, 120 mL of pyridine and 2000 mL of acetone were added and stirred at room temperature. 1650 g of acetyl chloride was slowly added dropwise thereto, and the mixture was further stirred at 50 캜 for 8 hours. After the reaction, the reaction solution was allowed to cool to return to room temperature, and the reaction solution was poured into 20 L of methanol with vigorous stirring, whereby a white solid precipitated. The white solid was filtered off by suction filtration and washed three times with a large amount of methanol. The resulting white solid was dried at 60 캜 overnight, and then vacuum-dried at 90 캜 for 6 hours to obtain cellulose derivative 9.

The degree of substitution of the substituent in the glucose skeleton of the cellulose derivative 9 prepared above was measured in accordance with the method described in Cellulose Communication 6, 73-79 (1999) and Chirality 12 (9), 670-674 by ¹ H- NMR and &lt; ¹³ &gt; C-NMR, and the average value thereof was determined. As a result, the number of substituents of the butoxy group, which is a substituent having an ether bond, is 0.7, the number of substituents of the acetyl group is 1.4, the number of substituents of the benzoate group, which is an acetyl group- Was 0.4 and the total degree of substitution was 2.1.

(Production of retardation film 9)

A retardation film 9 was prepared in the same manner as in the production of the retardation film 1 except that the cellulose derivative 9 was used instead of the cellulose derivative 1.

<Example 4>

(Synthesis of Cellulose Derivative 10)

(First step)

A cellulose ether was prepared in the same manner as in Example 1.

(Second Step)

To a 3 L three-necked flask equipped with a mechanical stirrer, a thermometer, a cooling tube and a dropping funnel, 200 g of the cellulose ether obtained in the first step, 120 mL of pyridine and 2000 mL of acetone were added and stirred at room temperature. 42 g of thiophene-2-carbonyl chloride was slowly added dropwise, followed by further stirring at 50 DEG C for 8 hours. After the reaction, the reaction solution was allowed to cool to return to room temperature, and the reaction solution was poured into 20 L of methanol with vigorous stirring, whereby a white solid precipitated. The white solid was filtered off by suction filtration and washed three times with a large amount of methanol. The resulting white solid was dried at 60 캜 overnight, and then vacuum-dried at 90 캜 for 6 hours to obtain a cellulose derivative 10.

The degree of substitution of the substituent in the glucose skeleton of the cellulose derivative 10 prepared above was measured in accordance with the method described in Cellulose Communication 6, 73-79 (1999) and Chirality 12 (9), 670-674 by ¹ H- NMR and &lt; ¹³ &gt; C-NMR, and the average value thereof was determined. As a result, the number of substituents in the butoxy group, which is a substituent having an ether bond, is 0.7, the number of substituents in the acetyl group is 1.4, the number of substituents in the thiophenecarbonyl group, which is an acetyl group- Was 0.4 and the total degree of substitution was 2.1.

(Production of the retardation film 10)

The retardation film 10 was prepared in the same manner as in the production of the retardation film 1 except that the cellulose derivative 10 was used in place of the cellulose derivative 1.

&Lt; Comparative Example 7 &

"Pure Ace" WR-W142 manufactured by Dainippon Ink &amp; Chemicals, Inc. was used as the retardation film 11.

For the retardation films 1 to 11, the following evaluations were performed. The results are shown in Table 2.

(Haze evaluation)

The haze was measured using a haze meter (NDH2000 manufactured by Nippon Denshoku Kogyo K.K.) under an environment of 23 ° C and 55% RH.

(Evaluation standard)

?: Haze was less than 0.1.

?: Haze was 0.1 or more and less than 0.5.

X: Haze was 0.5 or more.

(Brittleness evaluation)

The circular polarizer was manufactured by the following method, and the prepared circular polarizer was cut into 5 cm square, immersed in water for 30 minutes, and the film was peeled off from the circular polarizer to evaluate the embrittlement.

(Production method of circular polarizer)

The polyvinyl alcohol film having a thickness of 120 占 퐉 was uniaxially stretched (temperature: 110 占 폚, stretching magnification: 5 times). This was immersed in an aqueous solution containing 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds and then immersed in an aqueous solution at 68 캜 containing 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer. (Konica Minolta Tact KC4UY, thickness: 40 mu m, manufactured by Konica Minolta Co., Ltd.) was attached to the back surface side of the polarizer so that the slow axis of the retardation films 1 to 11 and the absorption axis of the polarizer were 45 DEG. Were bonded to each other by a sieve, thereby preparing circularly polarizing plates.

(Evaluation standard)

A: No peeling of the film at the time of peeling was observed.

X: Film peeled when peeling off.

(Adhesiveness to Polarizer)

Each of the polarizing plates prepared above was stored for 24 hours under an atmosphere of 23 ° C and 80% RH. Thereafter, it was confirmed whether or not the peelability by hand could be measured and peeled off under an atmosphere of copper.

(Evaluation standard)

○: It was not possible to peel by hand. Or only the end portion was peeled off, and further peeling off, the member was destroyed.

X: Parts other than the end portion could be peeled by hand.

(Fabrication of organic EL cell)

Using a 50-inch (127 cm) non-alkali glass having a thickness of 3 mm, according to the method described in the embodiment of Japanese Patent Application Laid-Open No. 2010-20925, An organic EL cell was fabricated.

(Fabrication of organic EL display)

An adhesive was applied to the surfaces of the retardation films 1 to 11 of each of the circularly polarizing plates prepared above and bonded to the viewer side of the organic EL cell to manufacture an organic EL display.

(Evaluation of organic EL display)

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

(Black color humidity stability)

A black image was displayed on the organic EL display under the condition that the illuminance at a position 5 cm higher than the outermost surface of each organic EL display was 1000 Lx under a low humidity environment of 23 占 폚 and 20% RH. Subsequently, a black image was similarly displayed under a high humidity environment of 23 DEG C and 80% RH. Under the above two conditions, the color of the black image from the front position (0 deg. With respect to the plane normal) of each organic EL display and the inclination angle of 40 deg. With respect to the plane normal was compared and the influence on the black color Were evaluated according to the following criteria by 10 general monitors. Further, when it was ◯ or more, it was judged that the humidity stability of black color was practically possible.

(Evaluation standard)

&Amp; cir &amp; &amp; cir &amp; &amp; cir &amp;

&Amp; cir &amp;: It was judged that there was no influence of humidity of black coloring of 5 to 8 monitors.

X: The number of monitors judged to have no influence of the displayed black humidity was 4 or less.

(Antireflection performance humidity stability)

An organic EL display for evaluation was prepared in the same manner as in the production of the organic EL display except that red, blue, and green lines were applied to the surface of the viewer side with Magic ink (Magic ink) Respectively. Under the condition that the illuminance at a position 5 cm higher than the outermost surface of each organic EL display was 1000 Lx, the organic EL display having the red, blue, The visibility (reflection performance) of the magic ink line displayed on the EL display was evaluated. Subsequently, visibility (reflection performance) of the magic ink line was similarly evaluated by 10 general monitors according to the following criteria under a high humidity environment of 23 캜 and 80% RH. If it is ◯ or more, it is determined that the humidity stability of the reflection performance is practically possible. Here, the reflection performance refers to reflection in the organic EL cell inside the circular polarizer, not reflection on the surface of the circular polarizer.

(Evaluation standard)

&Amp; cir &amp; &amp; cir &amp; &amp; cir &amp;

?: Five to eight monitors were judged to have no visibility effect of magic ink lines due to humidity.

X: 4 or less monitors judged that the visibility of the magic ink line due to humidity was not affected.

[Table 1]

  [Table 2]

As shown in Tables 1 and 2, the optical films (retardation films 1 and 8 to 10) of Examples 1 to 4, in which the degree of substitution satisfied the numerical ranges of the formulas (1) to (3) Brittleness was excellent. These optical films also exhibited excellent adhesiveness to the polarizer, and the organic EL display manufactured using the same showed excellent black color and antireflection performance.

On the other hand, the optical film (retardation film 2) of Comparative Example 1 in which the average degree of ester substitution was less than the lower limit of the formula (2) had a large haze. The optical films (the retardation film 3 and the retardation film 4) of Comparative Example 2 and Comparative Example 3 in which the ester average degree of substitution exceeded the upper limit of the formula (2) had a black color feeling and antireflection performance It was not excellent. Further, the optical film (retardation film 5) of Comparative Example 4 in which the ether average degree of substitution exceeds the upper limit of the formula (3) and the total degree of substitution exceeds the upper limit of the formula (1) The antireflection performance of the organic EL display manufactured by the present invention was not excellent. In addition, the optical film (the retardation film 6) of Comparative Example 5 in which the total degree of substitution was less than the lower limit of the formula (1) had a large haze, and the black color and antireflection performance of the organic EL display produced using the same were not excellent. The optical film (the retardation film 5) of Comparative Example 6 in which the ether average degree of substitution was less than the lower limit of the formula (3) was poor in adhesiveness to the polarizer. In addition, the optical film (the retardation film 11) of Comparative Example 7 in which a modified polycarbonate was used instead of a cellulose derivative as the resin had bad adhesiveness with the polarizer.

This application is based on Japanese Patent Application No. 2013-193688 filed on September 19, 2013, the contents of which are incorporated herein.

In order to express the present invention, although the present invention has been appropriately and fully described through the embodiments with reference to the drawings in the above description, those skilled in the art will recognize that it is easy to modify and / or improve the above- do. Accordingly, unless the person skilled in the art is of a type or mode of modification that is beyond the scope of the claims as set forth in the claims, the mode of modification or the mode of modification is to be construed as being covered by the scope of the claims.

According to the present invention, it is possible to obtain a long optical film which exhibits a sufficient retardation, exhibits a retardation in retardation due to humidity fluctuations, is excellent in adhesion to polarizers and in embrittlement, and suppresses increase in haze. Therefore, the present invention can be suitably used in, for example, an image display apparatus or the like which is required to obtain a good contrast or a hue balance with a wide viewing angle. Further, according to the present invention, there is provided a circularly polarizing plate and an organic electroluminescence display device including the long optical film.

A Slope Stretch Device Entrance
B Position at the end of drawing
District Ci, Co
D1 Direction of release
D2 winding direction
F cellulose acylate film
Ri, Ro rail
100 organic EL display
200 organic EL device
300 Won polarizer
1 transparent substrate
2 metal electrode
3 TFT
4 organic light emitting layer
5 Transparent electrode
6 insulating layer
7 sealing layer
8 film
9 phase difference film
10 Polarizer
11 Protective film
12 cured layer
13 Antireflection layer
15 oblique stretching device
16 Film Feeder
17 Return direction changing device
18 retractor
19 Deposition system
111, 112 stretching direction
113 Transport direction
114 ground shaft

Claims (6)

Containing a cellulose derivative and silica-based fine particles,
The angle formed by the long direction and the slow axis is 40 to 50 degrees,
Plane retardation Ro ₅₅₀ at a wavelength of 550 nm is not less than 120 nm and not more than 160 nm,
Satisfies the following formulas (1) to (3).
1.8 &lt; / = (One)
0.3? X _ES? 1.5 ... (2)
0.3? X _ETH ? (3)
Wherein X _ES is the average degree of ester substitution of the cellulose derivative, X _ETH is the ether average degree of substitution of the cellulose derivative, and Y is the total degree of substitution of the cellulose derivative) The method according to claim 1,
If the ratio of the wavelength retardation Ro ₄₅₀ at 450nm for _{Ro 550 (Ro 450 / Ro 550} ) is 0.70 or more 0.98 or less, a long optical film. 3. The method according to claim 1 or 2,
The cellulose derivative has a multiple binding group having an absorption maximum at a wavelength of 220 nm or more and 350 nm or less,
Wherein the average degree of substitution of the multiple binding groups in the cellulose derivative is not less than 0.3 and not more than 0.7. 4. The method according to any one of claims 1 to 3,
Wherein the film thickness is in the range of 20 to 60 mu m. A circular polarizer, wherein a long optical film according to any one of claims 1 to 4 and a polarizer are bonded. An organic electro luminescence display device comprising the circular polarizer according to claim 5.

Images