KR20190104219A - λ / 4 retardation film, circularly polarizing plate, and organic EL display device - Google Patents

Abstract

The objective of this invention is a (lambda) / 4 phase (s) difference film which consists of a cellulose ether derivative and a lignin derivative, and provides the (lambda) / 4 phase (s) difference film with few defect sites resulting from foaming at the time of solution film forming, and coloring was suppressed. (Lambda) / 4 phase (s) difference film of this invention contains the cellulose ether derivative which has an aromatic containing group, the lignin derivative, an acid, or its salt.

Description

λ / 4 retardation film, circularly polarizing plate, and organic EL display device

The present invention relates to a lambda / 4 phase difference film, a circularly polarizing plate and an organic EL display device.

In the organic EL display device, the light source itself can be ON / OFF driven independently for each pixel, and the power consumption of the organic EL display device is smaller than that of the liquid crystal display device in which the backlight is always lit during image display. In addition, in order to control the transmission and non-transmission of light for each pixel at the time of image display, compared with the liquid crystal display device in which a liquid crystal cell and polarizing plates provided on both surfaces thereof are essential, in an organic EL display device, by ON / OFF of the light source itself, Since formation of an image is possible, the structure similar to a liquid crystal display device becomes unnecessary, it is possible to obtain a very high front contrast, and it is expected to make it the display device excellent also in viewing angle characteristic. In particular, by using an organic EL element that emits light of each of B, G, and R colors, a color filter, which is essential for a liquid crystal display device, is also unnecessary, and therefore, higher contrast is expected to be obtained in an organic EL display device. .

In the organic EL display device, in order to efficiently extract light from the light emitting layer to the viewing side, a metal material having a high light reflectivity is used as the electrode layer constituting the cathode, or a metal plate is provided as a separate reflective member to have a mirror surface. It is common to provide a reflection member on the surface opposite to the light extraction surface.

In the organic EL display device, unlike the liquid crystal display device, as described above, the polarizing plates arranged in cross nicol are not provided. Therefore, the external light is reflected on the reflection member for light extraction and projection occurs, and the contrast tends to be greatly reduced in an environment with high illuminance.

On the other hand, for example, Patent Document 1 discloses a method of using a circularly polarized light element to prevent reflection of external light on a mirror surface. The circularly polarizing element described in patent document 1 is formed by laminating | stacking an absorption type linear polarizing plate and (lambda) / 4 phase (s) difference film so that each optical axis may cross | intersect by 45 degrees or 135 degrees.

In such a conventional λ / 4 retardation film, it is possible to adjust the monochromatic light by retardation of λ / 4 or λ / 2 of the light wavelength, but at each wavelength for white light, which is a synthetic wave in which light rays in the visible light region are mixed. There exists a problem that distribution generate | occur | produces in the polarization state of and converts into colored polarization. This means that the material constituting the λ / 4 retardation film is λ / 4 at the blue wavelength of 450 nm or the red wavelength of 650 nm even if the phase difference is λ / 4 with respect to the phase difference, for example, 550 nm of green monochromatic light. This is due to not being a phase difference. In order to suppress this phenomenon, (lambda) / 4 phase (s) difference film is desired to have wavelength dispersion which a phase difference also increases as a wavelength becomes large.

From such a situation, various examinations are made about the wideband phase difference plate which can give the phase difference adjusted to the phase difference of (lambda) / 4 or (lambda) / 2 with respect to the light of a wide wavelength range. For example, Patent Literature 2 bonds a λ / 4 wave plate having a phase difference of birefringent light to a quarter wavelength and a λ / 2 wave plate having a phase difference of birefringent light in a state where each optical axis crosses each other. One retarder is disclosed.

On the other hand, in order to manufacture the proposed retardation plate, a complicated step of adjusting the optical direction (optical axis or slow axis) of the two polymer films is required, and a plurality of films must be bonded by an adhesive layer. . As a result, the advantages of the organic EL display device that the thickness can be reduced are compromised. Therefore, development of a broadband? / 4 retardation film having a single layer structure that does not require lamination is required.

As a technique for obtaining a broadband λ / 4 retardation film in a single layer configuration, for example, Patent Document 3 discloses a polymer film obtained by copolymerizing a monomer unit of a polymer having positive refractive index anisotropy and a monomer unit having negative birefringence. The method of making it into (lambda) / 4 phase (s) difference film by uniaxial stretching is disclosed. Since this uniaxially stretched polymer film has wavelength dispersion that the phase difference also increases as the wavelength increases, it becomes possible to produce a wideband? / 4 plate with one phase difference film. However, there exists a problem in the adhesiveness with respect to the polarizer required as a polarizing plate protective film, and there exists a problem that a total light transmittance is not fully obtained.

Generally, when the retardation variation rate of resin used for retardation film is large, it is easy to be influenced by the subtle temperature nonuniformity and air volume nonuniformity in an extending apparatus. The variation rate here refers to how much the phase difference fluctuates when the stretching temperature is changed. If the variation is large, the phase difference fluctuation rate is large, and the value of the phase difference is sensitive to the stretching temperature.

In the case of polycarbonate-based resin, this phase difference fluctuation rate is large, and since the phase difference largely changes only by slight fluctuation | stretching temperature, phase difference nonuniformity tends to arise. In addition, since polycarbonate has a large photoelasticity, the retardation is largely changed by slight stress, and the retardation of the film is changed even by slight stress generated during assembling or environmental change, resulting in uniformity and stability of the screen. There was a problem.

In the case of cellulose ester-type resin, reverse wavelength dispersibility can be improved by increasing substitution degree, and also the phase difference fluctuation rate is small. Therefore, since the phase difference fluctuation by the fluctuation of extending | stretching temperature becomes small, there is little fluctuation | variation of a phase difference and a nonuniformity hardly arises. However, since it has the characteristic that retardation expression property will fall when a substitution degree is made high, in order to obtain a wideband (lambda) / 4 phase (s) difference film in a single | mono layer, it is necessary to lower extending | stretching temperature or enlarge a draw ratio, but it breaks at the time of extending | stretching. There is a problem that this tends to occur. In addition, although the film thickness can be made thick, it can be set as the phase difference value of a preferable range, However, when used for the reflection prevention using the circularly polarizing element of an organic electroluminescent display, the advantage of the organic electroluminescent display of thinning is impaired.

In the case of a cellulose ether-type resin, the retardation variation rate is small, there is no nonuniformity and the said retardation developability, and a necessary retardation can be obtained without making a film thick. For example, Patent Document 4 discloses a retardation film containing a cellulose ether derivative. Especially, since the cellulose ether-type resin which has an aromatic containing group has wavelength dispersion property which a phase difference increases as a wavelength becomes large, it is suitable as a material of (lambda) / 4 phase (s) difference film which can express the phase difference of (lambda) / 4 in broadband. Do.

Japanese Patent Laid-Open No. 8-321381 Japanese Patent Laid-Open No. 10-68816 International Publication No. 2000/026705 Japanese Patent No. 4750982

The film containing such a cellulose ether-type resin (henceforth a cellulose ether derivative) can be manufactured, for example by the solution film forming method. Specifically, the film containing a cellulose ether derivative can be manufactured through the process of carrying out the dope which melt | dissolved a cellulose ether derivative in the solvent on a support body, and then drying and peeling it. A cellulose ether derivative may form a mixture with the lignin derivative derived from the raw material, for example. However, in the process of manufacturing a film using such a cellulose ether derivative, there existed a problem that foaming was easy to occur at the time of drying flexible dope on a support body, and a defect site was easy to generate | occur | produce in the (lambda) / 4 phase (s) difference film obtained. Moreover, there also existed a problem that coloring is easy to generate | occur | produce in the (lambda) / 4 phase (s) difference film obtained.

This invention was made | formed in view of such a situation, and is a (lambda) / 4 phase (s) difference film containing a cellulose ether derivative and a lignin derivative, there are few defect sites resulting from foaming at the time of solution film forming, and the (lambda) / 4 phase (s) difference film which coloring was suppressed was carried out. It aims to provide.

[1] A lambda / 4 retardation film containing a cellulose ether derivative having an aromatic containing group, a lignin derivative, an acid or a salt thereof.

[2] [lambda] / 4 according to [1], wherein the alkoxy group included in the cellulose ether derivative is an aliphatic alkoxy group, the aromatic containing group is an aromatic acylate group, and the cellulose ether derivative satisfies the following formula (I): Retardation film.

Formula (I): 1.5≤X + Y≤3.0

        1.0≤X≤2.5

        0.1≤Y≤1.0

(In formula (I),

X is a degree of substitution of the aliphatic alkoxy group,

Y is a substitution degree of the said aromatic acylate group)

[3] The lambda / 4 retardation film according to [1] or [2], wherein the acid is an organic acid having an aromatic ring.

[4] The lambda / 4 phase difference film according to any one of [1] to [3], wherein the content of the acid or its salt is 0.5 to 500 mass ppm with respect to the total mass of the cellulose ether derivative.

[5] The lambda / 4 phase difference film according to any one of [1] to [4], further comprising at least one additive selected from the group consisting of a phenol compound, a phosphite compound and a benzotriazole compound.

[6] an angle between the polarizer and the lambda / 4 phase difference film according to any one of [1] to [5], wherein an angle between the in-plane slow axis of the lambda / 4 phase difference film and the absorption axis of the polarizer is 40 to Circular polarizer, which is 50 °.

[7] An organic EL display device comprising an organic EL element and the circularly polarizing plate described in [6].

This invention is a (lambda) / 4 phase (s) difference film containing a cellulose ether derivative and a lignin derivative, there can be provided the broadband (lambda) / 4 phase (s) retardation film with few defect sites resulting from foaming at the time of solution film forming, and suppressing coloring.

1: is a top view which shows an example of a structure of diagonal stretch apparatus.
2 is a plan view illustrating an example of a rail pattern of a drawing portion.
3 is a schematic diagram illustrating an example of a configuration of an organic EL display device.

As mentioned above, in the process of manufacturing the film containing the cellulose ether derivative and lignin derivative which have an aromatic containing group by the solution film forming method, although the mechanism which generate | occur | produces a bubble is not clear, it guesses as follows.

That is, when drying a film | membrane on a support body, drying starts from the surface, At this time, if there exists a part which a solvent tends to trap, such as a part with a low density partially in a film | membrane, this solvent will dry-vaporize later. When the surface is dried to some extent, the vaporized solvent loses its place and easily bubbles in the film.

For example, the cellulose ether derivative which uses pulp as a raw material forms the mixture with comparatively many lignin derivatives. Since the lignin derivative is a so-called network-like molecule and has a three-dimensional structure, it is considered that a part of the molecule having the three-dimensional structure has a low density. In particular, in the case of the cellulose ether derivative having an aromatic containing group, since the aromatic portion and the lignin derivative are easy to interact, the mesh-shaped three-dimensional structure is more complicated, and as a result, the content ratio of the portion having a lower density is increased. It is thought that foaming is easy to be accelerated | stimulated.

Moreover, although the mechanism in which the film containing the cellulose ether derivative and lignin derivative which have an aromatic containing group generate coloring and discoloration is not clear, it is guessed as follows.

That is, it is thought that the lignin derivative itself is colored, and that the lignin derivative is easily decomposed by light or heat, thereby causing discoloration or coloring. In particular, in the manufacturing process of the film, the lignin derivative is caused to foam, and the distribution of lignin is unevenly distributed around the foam, and therefore, light and heat also act non-uniformly, so that coloring and discoloration are likely to be amplified easily.

Therefore, in order to reduce the defect site | part resulting from foaming of the (lambda) / 4 phase (s) difference film obtained, and to suppress coloring and discoloration, it is desired to make content of the lignin derivative contained in a cellulose ether derivative as small as possible. However, in order to make content of lignin derivative highly low, it is expensive. Therefore, when using the cellulose ether derivative in which a small amount of lignin derivatives remain, it is desired that foaming, coloring, and discoloration can be suppressed.

On the other hand, the present inventors discovered that foaming in the manufacturing process of a film and coloring of a film can be suppressed by adding "acid or its salt" further. This mechanism is not obvious, but is assumed as follows. That is, an acid or its salt acts on the hydroxyl group of a lignin derivative, weakens formation of the hydrogen bond which comprises a three-dimensional structure, and makes it easy to loosen a three-dimensional structure. As a result, it is thought that the content ratio of the low-density part in the three-dimensional structure in a lignin derivative can be suppressed, foaming can be suppressed, and the nonuniformity of coloring can also be improved. This invention is made | formed based on this knowledge.

1.λ / 4 retardation film

(lambda) / 4 phase (s) difference film contains a cellulose ether derivative, a lignin derivative, an acid, or its salt.

<Cellulose ether derivative>

The cellulose ether derivative is a compound in which at least part of the hydroxyl group of cellulose is substituted with an alkoxy group (-OR).

R in the alkoxy group (-OR) is an aliphatic hydrocarbon group or an aromatic group.

It is preferable that it is 1-20, as for the carbon atom number of an aliphatic hydrocarbon group, it is more preferable that it is 1-12, and it is still more preferable that it is 1-6. The aliphatic hydrocarbon group may be any of linear, branched and cyclic groups. It is preferable that an aliphatic hydrocarbon group is an unsubstituted aliphatic hydrocarbon group. It is preferable that it is an alkyl group, and it is more preferable that it is a linear alkyl group. Especially, a methyl group or an ethyl group is especially preferable.

An aromatic group is an aromatic hydrocarbon group or an aromatic heterocyclic group.

The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 to 24, more preferably 6 to 12, and even more preferably 6 to 10. 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, preferably a phenyl group, a naphthyl group and a biphenyl group, and more preferably a phenyl group and a naphthyl group.

The aromatic heterocyclic group preferably contains at least one of an oxygen atom, a nitrogen atom or a sulfur atom, and examples thereof include furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole and tri Azine, indole, indazole, purine, thiazolin, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine And groups derived from aromatic heterocycles such as acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole and tetrazaindene. Especially, a pyridyl group, a thiophenyl group, a triazinyl group, and a quinolyl group are preferable.

Especially, it is preferable that an aromatic group is an aromatic hydrocarbon group.

The cellulose ether derivative may further have a substituent other than the alkoxy group (-OR). Examples of other substituents include an acylate group (-O-COR). R of an acylate group (-O-COR) is an aliphatic hydrocarbon group or an aromatic group. An aliphatic hydrocarbon group and an aromatic group are synonymous with the aliphatic hydrocarbon group and aromatic group represented by R of an alkoxy group (-OR), respectively.

As for at least one part of R of the alkoxy group (-OR) contained in a cellulose ether derivative, or at least one part of R of an alkoxy group (-OR) and / or an acylate group (-O-COR), it is more preferable that it is an aromatic group. . That is, it is preferable that at least one part of the alkoxy group (-OR) and / or acylate group (-O-COR) contained in a cellulose ether derivative is an aromatic containing group. If at least one part of the alkoxy group (-OR) and / or acylate group (-O-COR) contained in a cellulose ether derivative is an aromatic containing group, wavelength dependency of retardation can be provided to a film. Thereby, the (lambda) / 4 phase (s) difference film which expresses (lambda) / 4 phase (s) difference in a wide wavelength range can be obtained. An aromatic containing group is group containing an aromatic group, and as mentioned above, R means an alkoxy group (-OR), an acylate group (-O-COR), etc. which are aromatic groups.

Among them, from the viewpoint of easy synthesis, the cellulose ether derivative includes an alkoxy group (-OR) and an acylate group (-O-COR), and R in the alkoxy group (-OR) is an aliphatic hydrocarbon group, It is more preferable that R of an acylate group (-O-COR) is an aromatic group.

It is preferable that the total substitution degree of a cellulose ether derivative is 1.5-3.0. The total substitution degree of a cellulose ether derivative is the whole cellulose ether derivative of the sum total of the alkoxy group and other substituents (such as an acylate group) substituted by the hydroxyl group of 2-position, 3-position, and 6-position in a glucose skeleton. Means the average value (average degree of substitution). If the total substitution degree of a cellulose ether derivative is 1.5 or more, since it is easy to adjust DSP to less than 1 and Ro may also be easy to adjust to a fixed or more while reducing the variation of the phase difference with respect to humidity fluctuations.

Among these, it is preferable that it is 0.05-1.2, and, as for the substitution degree of the aromatic containing group of a cellulose ether derivative, it is more preferable that it is 0.1-1.0. If the degree of substitution of the aromatic-containing group is 0.05 or more, the DSP can be made low while reducing the variation in the phase difference with respect to the humidity variation and preventing the Ro from being excessively low. That is, wavelength dependence can be provided to the phase difference of a film. When substitution degree of an aromatic containing group is 1.2 or less, it can suppress that DSP becomes too low.

As mentioned above, it is preferable that a cellulose ether derivative contains an aliphatic alkoxy group (-OR, R: aliphatic hydrocarbon group) and an aromatic acylate group (-O-COR, R: aromatic group). In this case, it is preferable that it is 0.9-2.7, and, as for the substitution degree of the aliphatic alkoxy group (-OR) of a cellulose ether derivative, it is more preferable that it is 1.0-2.5. If the substitution degree of an aliphatic alkoxy group is fixed or more, it can suppress that DSP becomes too low. If the substitution degree of an aliphatic alkoxy group is fixed or less, it can suppress that the retardation expression property by extending | stretching is significantly impaired. As mentioned above, it is preferable that it is 0.05-1.2, and, as for the substitution degree of the aromatic acylate group of a cellulose ether derivative, it is more preferable that it is 0.1-1.0. That is, it is especially preferable that a cellulose ether derivative satisfy | fills following formula (I).

Formula (I): 1.5≤X + Y≤3.0

        1.0≤X≤2.5

        0.1≤Y≤1.0

(In formula (I),

X is a degree of substitution of an aliphatic alkoxy group,

Y is the degree of substitution of the aromatic acylate group)

Substitution degree of the aliphatic alkoxy group of a cellulose ether derivative is the average value (average degree of substitution) in the whole cellulose ether derivative of the sum total of the aliphatic alkoxy group substituted by the hydroxyl group of 2-position, 3-position, and 6-position in a glucose skeleton. it means. Similarly, the substitution degree of an aromatic containing group means the average value (average substitution degree) in the whole cellulose ether derivative of the sum total of the aromatic containing group substituted by the hydroxyl group of 2nd-position, 3rd-position, and 6th-position in a glucose skeleton. .

Substitution degree of the alkoxy group and aromatic containing group of a cellulose ether derivative is ¹ H-NMR or ¹³ C-NMR using the method of Cellulose Communication 6, 73-79 (1999), and Chrality 12 (9), 670-674. It can measure by.

The mass average molecular weight (Mw) of the cellulose ether derivative is preferably in the range of 7 × 10 ³ to 10000 × 10 ³ , and more preferably in the range of 15 × 10 ³ to 5000 × 10 ³ . If the mass average molecular weight of a cellulose ether derivative is more than fixed, it will be easy to raise the mechanical strength of a film, and if it is below fixed, the solubility with respect to the solvent at the time of film forming will be hard to be impaired. It is preferable that it is 1.1-10, and, as for molecular weight distribution (MWD), it is more preferable that it is 1.5-8.0.

The measurement of mass average molecular weight (Mw) and molecular weight distribution (MWD) can be performed using gel permeation chromatography (GPC). Specifically, N-methylpyrrolidone is used as a solvent, and can be calculated | required using the conversion molecular weight calibration curve previously calculated | required from the structural curve of standard monodisperse polystyrene using a polystyrene gel.

A cellulose ether derivative can be manufactured with reference to a well-known method, for example, the method described in "The Dictionary of Cellulose" pages 131 to 164 (Asakura Bookstore, 2000) and the like. Specifically, cellulose which is not substituted at all, or a cellulose ether in which a part of hydroxyl groups in 2, 3 and 6 positions are etherified (substituted by an alkoxy group (-OR)) is used as a raw material. For example, a cellulose ether derivative can be obtained by dissolving cellulose or cellulose ether of a raw material in a suitable organic solvent, reacting an acid chloride or an acid anhydride in the presence of a base such as pyridine, and esterifying the remainder of the hydroxyl group. As a raw material of the cellulose ether used as a raw material, a well-known raw material can be used, for example, the cellulose which uses pulp as a raw material can be used.

Lignin derivatives

As described above, the lignin derivative may be mainly derived from a raw material of the cellulose ether derivative, but may be artificially included. Content of the lignin derivative may be 0.1-10.0 mass% with respect to the total mass of a cellulose ether derivative. It is preferable that content of the lignin derivative is less than 5 mass% with respect to the total mass of a cellulose ether derivative from a viewpoint of making it easy to suppress foaming in a film manufacturing process and coloring of a film.

Content of the lignin derivative in (lambda) / 4 phase (s) difference film can be measured with the following method. That is, using the finely ground film as a sample, the amount of the lignin derivative contained in the sample is measured in accordance with the pulp material-lignin content rate test method of JAPANTAPPI paper pulp test method No. 61: 2000.

<Acid or salt thereof>

The acid may be an inorganic acid or an organic acid.

Examples of the inorganic acid include hydrochloric acid and sulfuric acid.

Examples of the organic acid include aliphatic carboxylic acid and aromatic carboxylic acid (organic acid having an aromatic ring). Examples of aliphatic carboxylic acid include acetic acid, propionic acid and the like. Examples of the aromatic carboxylic acid include benzoic acid, 3-thiophenecarboxylic acid, picolinic acid, nicotinic acid, 4-methoxybenzoic acid, trimethoxybenzoic acid, naphthoic acid, phthalic acid and the like.

Examples of the metal which forms a salt of an acid include alkali metals such as sodium and potassium; Alkaline earth metals such as calcium, magnesium and the like are included, and preferably sodium, potassium or magnesium.

Especially, organic acid or its salt is preferable and aromatic carboxylic acid or its salt is more preferable. Aromatic carboxylic acids or salts thereof have a high compatibility with lignin derivatives, and thus act highly on the hydroxyl groups of the lignin derivatives, making it easier to weaken the formation of hydrogen bonds constituting the three-dimensional structure, and more loosen the three-dimensional structure. Because it is easy to do.

The average molecular weight of the acid or salt thereof can be 36 to 250, for example. An acid or its average molecular weight can be measured as a relative molecular weight by mass spectrometry etc.

It is preferable that content of an acid or its salt is 0.1-600 mass ppm with respect to the total mass of a cellulose ether derivative. If the content of the acid or its salt is 0.1 mass ppm or more, foaming and coloring derived from the lignin derivative are highly suppressed, and if the content is 600 mass ppm or less, the ester bond of the cellulose ether derivative can be highly suppressed. Thereby, distribution of the molecular weight and substitution degree of a cellulose ether derivative becomes wide, and the fall of haze by the compatibility declines can be highly suppressed. As for content of an acid or its salt, it is more preferable that it is 0.5-500 mass ppm with respect to the total mass of a cellulose ether derivative.

Content of an acid or its salt can be measured by ion chromatography. Measurement conditions can be performed as follows.

(Pretreatment)

The film is finely ground, 500 mg (M) of the sample is weighed into a container made of PP, and 10 ml of ultrapure water is added. After disperse | distributing this for 30 minutes with an ultrasonic cleaner, it filters with an aqueous chromatographic disc (0.45 micrometer), and makes the liquid obtained as a sample.

(Measure)

Apparatus: DX-500 made by ion chromatograph DIONEX

Column: DIONEX IonPac ICE-AS1

Suppressor: AMMS-II

Eluent: 1.0 mM-octane sulfonic acid

Regeneration solution: 5.0 mM-tetrabutylammonium hydroxide (delivered with high purity nitrogen 5 psi)

Flow rate: 1.0ml / min

Injection volume: 25 μl

Conversion method: Content (mass ppm) = measured value (mg / l) / 1000 × 10 / M (mg) × 1000000

<Other Ingredients>

(lambda) / 4 phase (s) difference film may further contain another component in the range which does not impair the effect of this invention. Examples of other components include additives such as ultraviolet absorbers, antioxidants, light stabilizers, matting agents (particulates), and the like.

(UV absorber)

Examples of ultraviolet absorbers include benzotriazole compounds, benzophenone compounds, triazine compounds and the like. Especially, a benzotriazole type compound and a benzophenone type compound are preferable at the point that the coloring of a film is comparatively few, and a benzotriazole type compound is more preferable.

(Benzotriazole compound)

A benzotriazole type compound is a compound which has a benzotriazole skeleton. Examples of the benzotriazole-based compound include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole and 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotria Sol, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl)- 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], 2- (2'-hydroxy-3'-t -Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and branched dodecyl) -4-methylphenol, octyl-3- [ 3-t-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-t-butyl-4-hydroxy -5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate and the like. Examples of commercially available products include TINUVIN (registered trademark) 111FDL, East 928, East 1130, East 123, East 123-DW, East 144, East 152, East 1577ED, East 1600, East 171, East 213, East 234, East 292, Copper 292HP, copper 312, copper 326, copper 328, copper 329, copper 360, copper 384-2, copper 400 (above, manufactured by BASF Japan, trade name); Adeca staff LA-24, East LA-29, East LA-31, East LA-31RG, East LA-31G, East LA-32, East LA-36, East LA-36RG (above, made by Adeka Corporation) are included do.

It is preferable that it is 0.1-5.0 mass% with respect to the total mass of a cellulose ether derivative, and, as for content of a ultraviolet absorber, it is more preferable that it is 0.5-5.0 mass%. When content of a ultraviolet absorber is 0.1 mass% or more, it is easy to suppress photolysis of resin highly, and when it is 5 mass% or less, the optical characteristic of the film obtained is hard to be impaired.

(Light stabilizer)

Examples of the light stabilizer include a hindered amine compound. Examples of commercially available products of the hindered amine compound include adecastab LA-52, copper LA-57, copper LA-63P, copper LA-68, copper LA-72, copper LA-77Y, copper LA-77G and copper LA. -81, LA-82, LA-87, LA-402AF, LA-502XP (above, Adekaze Co., Ltd.) are included.

(Antioxidant)

Examples of the antioxidant include phenolic compounds (including hindered phenolic compounds), phosphite compounds and thioether compounds. Especially, a phenol type compound and a phosphite type compound are preferable and a phenol type compound is more preferable.

(Phenolic compound)

A phenol type compound is a compound which has a phenol skeleton or a hindered phenol skeleton. Examples of the phenolic compound include 2,6-di-t-butyl-4-hydroxytoluene (BHT) and pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl ) Propionate], octadodecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris (3,5-di-tert-butyl-4-hydroxybenzyl Isocyanurate, 4,4'-butylidenebis- (3-methyl-6-t-butylphenol), triethyleneglycol-bis [3- (3-t-butyl-4-hydroxy-5 -Methylphenyl) propionate], 3,9-bis [2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] -2, 4,8,10-tetraoxaspiro [5,5] undecane and the like. Examples of commercially available products include IRGANOX 1010, 1076, and 1726 (above, manufactured by BASF Japan); Adeka staff AO-20, copper AO-30, copper AO-40, copper AO-50, copper AO-60, copper AO-80, copper AO-330 and the like (above, manufactured by Adeka Co., Ltd.) are included. .

(Phosphite compound)

The phosphite compound is a compound having a P (OR) ₃ structure. R is an alkyl group, an alkylene group, an aryl group, an arylene group, etc. Three R may be same or different, and two R may form ring structure.

Examples of the phosphite compound include tris (2,4-di-tert-butylphenyl) phosphite, bis [2,4-bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphoric acid, bis ( 2,4-di-tert-butylphenyl) pentaerythritoldiphosphite, bis (2,4-dicumylphenyl) pentaerythritoldiphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) penta Erythritol-di-phosphite, trisnonylphenylphosphite, tris (2,4-di-tert-butylphenyl) phosphite, tri (o-tolyl) phosphine, tri (p-tolyl) phosphine, cyclo Hexyldiphenylphosphine, ethyldiphenylphosphine and the like. In the example of a commercial item, Adeka tab (registered trademark) PEP-36, copper PEP-8, copper HP-10, copper 2112, copper 1178, copper 1500, copper C, copper 135A, copper 3010, copper TPP (above, ah Decasa); SUMILIZER (registered trademark) GP (above, Sumitomo Chemical Co., Ltd.); Irgafos 38, 168, P-EPQ (above, all manufactured by BASF Japan), and the like.

It is preferable that it is 0.02-5 mass% with respect to the total mass of a cellulose ether derivative, and, as for content of antioxidant, it is more preferable that it is 0.05-3 mass%. When content of antioxidant is 0.02 mass% or more, decomposition | disassembly of resin is highly suppressed easily, and when 5 mass% or less, the optical characteristic of the film obtained is hard to be impaired.

Among these, it is preferable that (lambda) / 4 phase (s) difference film contains one or more chosen from the group which consists of a benzotriazole type compound as a ultraviolet absorber, a phenol type compound and a phosphite type compound as antioxidant. When the λ / 4 retardation film further contains these compounds, not only the ultraviolet absorbing function or the antioxidant function is obtained, but also the generation of bubbles in the film manufacturing process and coloring of the film can be further suppressed. Although the reason is not clear, the aromatic ring of the benzotriazole compound and the phenol compound easily interact with the aromatic ring of the cellulose ether derivative, and the phosphite compound has the interaction between the isolated electron pair of phosphorus and the aromatic ring of the cellulose ether derivative. I think that it is easy to do it. Thereby, it is thought that the interaction between molecules of the cellulose ether derivative is weakened, the intermolecular distance is widened, and the moving speed of solvent molecules between molecules is increased. Thereby, it is thought that the solvent which stays in a film | membrane reduces, and foaming is suppressed more highly.

(Mat made)

A mat agent (fine particle) has a function which raises the slipperiness of (lambda) / 4 phase (s) difference film. Examples of fine particles include inorganic materials such as silicon dioxide (SiO ₂ ), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate Particulates are included.

Especially, in order to reduce the increase of the haze of the film obtained, silicon dioxide is preferable. Examples of commercially available products of silicon dioxide particles include Aerosil R812, R972 (manufactured by Nippon Aerosil Corporation), NanoTek SiO ₂ (manufactured by CI Kasei Co., Ltd.), and the like.

The shape of the fine particles may be any of irregular shape, needle shape, flat shape and spherical shape, and is preferably spherical in that transparency of the resulting film is hardly impaired.

One type of microparticles may be used and may use 2 or more types together. Moreover, transparency and slipperiness | lubricacy may be made highly compatible by using together particle | grains and particle | grains (for example, needle shape, spherical shape, etc.) which differ.

It is preferable that the average primary particle diameter of microparticles | fine-particles is 5-50 nm. If the average primary particle diameter of microparticles | fine-particles is 5 nm or more, since the surface of a film can be roughened, it is easy to provide slipperiness, and if it is 50 nm or less, it is easy to suppress an increase of a haze. As for the average primary particle diameter of microparticles | fine-particles, it is more preferable that it is 5-30 nm.

Content of microparticles | fine-particles can be 0.1-5 mass% with respect to the total mass of a cellulose ether derivative, for example. When content of microparticles | fine-particles is 0.1 mass% or more, it is easy to fully raise the slipperiness | lubricacy of the surface of a film, and if it is 5 mass% or less, it is easy to suppress the increase of the haze of a film. As for content of microparticles | fine-particles, it is more preferable that it is 0.1-2.5 mass% with respect to the total mass of a cellulose ether derivative, and it is still more preferable that it is 0.3-2 mass%.

<Film properties>

(Phase Difference Ro and Rt)

It is preferable that in-plane phase difference Ro measured in the environment of measurement wavelength 550nm and 23 degreeC 55% RH of (lambda) / 4 phase (s) difference film satisfy | fills 30 nm <= R <= 300nm, It is more preferable that 50 nm <= R <= 250nm More preferably, 120 nm ≤ Ro ≤ 150 nm is satisfied. It is preferable that thickness direction retardation Rt measured in the environment of measurement wavelength 550nm and 23 degreeC 55% RH of (lambda) / 4 phase (s) difference film satisfy | fills 0nm <= Rt <= 200nm, and it is more preferable that it meets 0nm <= Rt <= 150nm. Do. The lambda / 4 phase difference film having such a phase difference is suitable as a lambda / 4 phase difference film of the organic EL display device, for example.

Ro and Rt of the λ / 4 retardation film are defined by the following formulas, respectively.

Equation (1): Ro = (nx-ny) × d

Equation (2): Rt = ((nx + ny) / 2-nz) × d

(In the meal,

nx is a refractive index in the direction x (in-plane slow axis direction) which becomes the largest in the in-plane direction of a film,

ny is the refractive index in the direction y orthogonal to the said direction x (in-plane slow-axis direction) in the in-plane direction of a film,

nz is a refractive index in the thickness direction of a film,

d is the film thickness (nm) of the film)

In-plane slow axis of (lambda) / 4 phase (s) difference film means the axis | shaft which refractive index becomes largest in a film surface. The in-plane slow axis of the λ / 4 retardation film can be confirmed by AxoScan manufactured by Axometrics.

It is preferable that it is 40-50 degrees, and, as for the orientation angle (angle which an in-plane slow axis and film width direction make) of (lambda) / 4 phase (s) difference film, it is more preferable that it is 45 degrees.

Measurement of Ro and Rt of (lambda) / 4 phase (s) difference film can be performed with the following method.

1) A (lambda) / 4 phase (s) difference film is humidified for 24 hours in 23 degreeC 55% RH environment. The average refractive index of this optical film is measured with an Abbe refractometer, and thickness d is measured using a commercially available micrometer.

2) Three-dimensional refractive index nx, ny, nz in wavelength 550nm of (lambda) / 4 phase (s) difference film after humidity control was measured using AxoScan by Axometrics company in the environment of 23 degreeC 55% RH, and refractive index nx, ny, nz Find the average value of. The obtained values are applied to the above formulas (1) and (2) to calculate Ro and Rt, respectively.

Retardation Ro and Rt of (lambda) / 4 phase (s) difference film can be adjusted mainly according to substitution degree and a draw ratio of a cellulose ether derivative. In order to make retardation Ro and Rt of (lambda) / 4 phase (s) difference film high, it is preferable to make high substitution degree of the alkoxy group of a cellulose ether derivative, low substitution degree of an aromatic containing group, or high draw ratio, for example. .

(DSP)

It is preferable that DSP of (lambda) / 4 phase (s) difference film is less than 1, and it is more preferable that it is more than 0.75 and 0.9 or less. It is because such (lambda) / 4 phase (s) difference film can express (lambda) / 4 phase (s) difference in a wide wavelength range.

The DSP measurement of (lambda) / 4 phase (s) difference film can be performed with the following method.

1) In the same manner as in the measurement of the retardation Ro described above, in-plane retardation value Ro at wavelengths of 450 nm and 550 nm of the λ / 4 retardation film was set to Axoscan manufactured by Axometrics under an environment of a temperature of 23 ° C and a relative humidity of 55%. Measure each using.

2) The in-plane retardation value Ro (450) at the wavelength 450 nm and the in-plane retardation value Ro (550) at the wavelength 550 nm are applied to the following equation (3) to calculate the wavelength dispersion value DSP. .

Equation (3): DSP = Ro (450) / Ro (550)

DSP of (lambda) / 4 phase (s) difference film can be adjusted with substitution degree of the aromatic containing group of a cellulose ether derivative, etc. In order to make DSP of a (lambda) / 4 phase (s) difference film low, it is preferable to make high the substitution degree of the aromatic containing group of a cellulose ether derivative, for example.

(Haze)

It is preferable that the haze of (lambda) / 4 phase (s) difference film is 0.01-2.0. When the haze of the lambda / 4 phase difference film is 2.0 or less, the contrast of the display image of the organic EL display device can be increased. As for the haze of (lambda) / 4 phase (s) difference film, it is more preferable that it is 0.01-1.0. The haze of (lambda) / 4 phase (s) difference film can be measured by a haze meter (model NDH 2000, Nippon Denshoku Co., Ltd. product).

Haze of (lambda) / 4 phase (s) difference film can be adjusted with content of an acid or its salt, etc. In order to lower the haze of (lambda) / 4 phase (s) difference film, it is preferable to make content of an acid or its salt into below fixed, for example.

(thickness)

The thickness of the λ / 4 retardation film may be, for example, 5 to 100 µm, preferably 5 to 60 µm, and more preferably 10 to 50 µm.

2. Method for producing λ / 4 retardation film

It is preferable that (lambda) / 4 phase (s) difference film of this invention is manufactured by the solution film forming method (cast method) from the point that a production efficiency is favorable and a film with high film thickness uniformity is easy to be obtained.

That is, (lambda) / 4 phase (s) difference film of this invention, 1) The process of obtaining the dope containing the above-mentioned cellulose ether derivative, lignin derivative, acid or its salt, and a solvent (dope preparation process), 2) the said dope After being flexible on a support body, it can be manufactured through the process of obtaining a film-like thing by drying and peeling (step of obtaining a film-like thing), and the process of extending | stretching the obtained film-like thing in diagonal direction (inclined drawing process).

About the process of 1) (dope manufacturing process)

The cellulose ether derivative, the lignin derivative, and the acid or its salt are dissolved in a solvent to prepare dope.

It is preferable that the solvent used for dope contains the organic solvent (good solvent) which can dissolve the above-mentioned cellulose ether derivative. Examples of such a good solvent include chlorine-based organic solvents such as methylene chloride (dichloromethane); Non-chlorine organic solvents, such as methyl acetate, ethyl acetate, acetone, and tetrahydrofuran, are contained. Especially, methylene chloride (dichloromethane) is preferable.

The solvent used for dope may further contain the poor solvent. Examples of the poor solvent include linear or branched aliphatic alcohols having 1 to 4 carbon atoms. When the ratio of alcohol in dope becomes high, a membrane-like thing will become easy to gelatinize and peeling from a metal support body will become easy. Examples of linear or branched aliphatic alcohols having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Among these, ethanol is preferable at the point that stability of dope, a boiling point are comparatively low, and dryness is also favorable.

Since an acid or its salt is hard to melt | dissolve with respect to the solvent which makes up the main component of a dope liquid, it is preferable not to melt | dissolve directly in a solvent, but to make it melt | dissolve after mixing with a cellulose ether derivative. The mixing of the cellulose ether derivative and the acid or its salt may be performed, for example, by dissolving the cellulose ether derivative in a solvent and then reprecipitating and purifying the solvent with an acid or its salt when reprecipitating and purifying with a solvent containing water. Can be. Thereby, the mixture which the cellulose ether derivative and the acid or its salt were mixed uniformly can be obtained, and an acid or its salt can be dissolved in a solvent by dissolving this mixture in a solvent.

About step (step of obtaining film-like article) of 2)

The obtained dope is flexible on a metal support body. Softening of dope can be performed by discharging from a casting die. Subsequently, the solvent in the dope cast on the metal support is evaporated to dryness, and then peeled off from the metal support to obtain a film.

Amount of residual solvent of the dope at the time of peeling from the metal support (the residual solvent amount at the time of separation S ₀₎ is preferably from 30 to 120% by weight. When the residual solvent amount S ₀ at the time of peeling is less than 120% by weight, since the force required when stripping the doped hard increases excessively, it is easy to suppress the breakage of the dope.

The residual solvent amount of dope is defined by the following formula. The same applies to the following.

Residual solvent amount (mass%) of dope = (mass after heat treatment of mass-dope before heat treatment of dope) / mass * 100 after heat treatment of dope

In addition, the heat processing at the time of measuring the amount of residual solvent means the heat processing for 120 degreeC 60 minutes.

About the process of 3) (inclined stretching process)

The obtained film is stretched in an inclined direction with respect to the width direction of the film. Specifically, it extends | stretches so that the orientation angle of the film obtained may be 40-50 degrees.

A draw ratio can be set to Tg-30-Tg + 80 degreeC, when the glass transition temperature of a cellulose ether derivative is made into Tg, for example. The stretching temperature can be adjusted mainly at the heating temperature in the stretching zone Z2 (see FIG. 2). The draw ratio is different depending on the properties of the film required, but may be, for example, 1.01 to 3.0 times (10% to 300%). The draw ratio is defined as (stretch direction size of the film after stretching) / (stretch direction size of the film before stretching).

The residual solvent in the film material of the S ₁ at the start of stretching is preferably from 5 to 20% by mass. When the amount of residual solvent S ₁ at the start of stretching is 5% by mass or more, the stretchability tends to increase due to the plasticizing effect by the residual solvent. If the residual solvent S ₁ at the beginning of stretching is less than 20% by mass, the film can be highly suppress the generation of air bubbles due to vaporization of the solvent in the shaped material. The residual solvent in the film material of the S ₁ at the start of stretching is more preferably, 8 to 15% by weight.

Stretching of the film-like article in the oblique direction can be performed by, for example, the oblique stretching apparatus shown in FIG. 1. 1: is a top view which shows an example of a structure of diagonal stretch apparatus. In the same figure, W represents a film-like article. As shown in FIG. 1, the diagonal stretch apparatus 10 has the feeding part 11, the conveyance direction change part 12, and the guide roll 13 in order from the conveyance direction upstream of a film-form (fabric film). ), A drawing section 14, a guide roll 15, a conveying direction changing section 16, and a winding section 17. The extending | stretching part 14 is mentioned later.

The feeding section 11 extracts the above-mentioned elongate film-like article and supplies it to the stretching section 14. The feeding part 11 may be comprised separately from the film forming apparatus of a film form, and may be comprised integrally.

The conveyance direction change part 12 changes the conveyance direction of the film | membrane thing unwound from the drawing | feeding-out part 11 to the direction toward the inlet of the extending | stretching part 14. The conveyance direction change part 12 is comprised including the turn bar which changes a conveyance direction by folding, for example conveying a film, and the turntable which rotates this turn bar in the plane parallel to a film.

At least one guide roll 13 is provided in the upstream side of the extending | stretching part 14, in order to stabilize the track | orbit at the time of running of a membranous thing. At least one guide roll 15 is provided in the downstream side of the extending | stretching part 14, in order to stabilize the track | orbit at the time of the running of the film-like thing obliquely stretched by the extending | stretching part 14.

The conveyance direction change part 16 changes the conveyance direction of the film | membrane after extending | stretching conveyed from the extending | stretching part 14 to the direction toward the winding-up part 17. FIG.

The winding-up part 17 winds the film conveyed through the conveyance direction change part 16 from the extending | stretching part 14, for example, a winder apparatus, a mounting apparatus, a drive apparatus, etc.

FIG. 2: is a top view which shows an example of the rail pattern of the extending | stretching part 14 typically. However, this is an example and the structure of the extending | stretching part 14 is not limited to this.

In the extending | stretching part 14, the film-form is diagonally stretched using the tenter (inclined stretching machine) which can be diagonally stretched. The extending | stretching part 14 runs along the heating zone Z, a pair of rails Ri and Ro, and the rails Ri and Ro from side to side, and many holding tools Ci and which convey a film-like thing, Co).

In FIG. 2, the feeding direction D1 of the film-like article differs from the winding direction D2 of the lambda / 4 phase difference film after stretching, and forms a feeding angle θi between the winding directions D2. The feeding angle [theta] i can be arbitrarily set to a desired angle in the range of more than 0 degrees and less than 90 degrees.

In this way, the feeding direction D1 and the winding direction D2 are different, and the movement distance of the gripping tool Co that travels the rail Ro is the movement of the gripping tool Ci that travels the rail Ri. It is longer than distance. Therefore, the rail pattern of a tenter is asymmetrical from side to side. And rail pattern can be adjusted manually or automatically according to the orientation angle | corner (theta), a draw ratio, etc. which should be given to a diagonal stretched film.

Heating zone Z has preheating zone Z1, extending zone Z2, and heat fixing zone Z3. In the extending | stretching part 14, the film hold | gripped by the holding tools Ci and Co passes through the preheating zone Z1, the drawing zone Z2, and the heat fixing zone Z3 in order. The preheating zone Z1 and the stretching zone Z2 are partitioned by partition walls, and the stretching zone Z2 and the heat fixing zone Z3 are partitioned by partition walls.

The preheating zone Z1 means that the holding tools Ci and Co gripping both ends of the film-like object at the inlet of the heating zone Z run while maintaining a constant distance from side to side (in the film width direction). Say the section. The stretching zone Z2 refers to a section until the interval between the gripping tools Ci and Co gripping both ends of the membrane-like body begins to open and reaches a predetermined interval. The row fixing zone Z3 is a section in which the interval between the holding tools Ci and Co after the stretching zone Z2 becomes constant again, and runs while the holding tools Ci and Co at both ends are parallel to each other. Say the section.

In the manufacturing apparatus 10 of such a diagonal stretched film, both ends of a film-form thing are hold | gripped with a pair of holding tools Ci and Co. And a film-like object is conveyed so that the movement distance of the holding tool Co may become longer than the moving distance of the holding tool Ci, and it extends | stretches in the diagonal direction with respect to the width direction.

The pair of holding tools Ci and Co face each other in a direction substantially perpendicular to the advancing direction (feeding direction D1) of the film at the inlet portion (the position of P in the drawing) of the stretching portion 14. It runs on a pair of left and right asymmetric rails Ri and Ro, respectively.

At this time, since the rails Ri and Ro are asymmetrical and have different lengths, the grip tools Ci and Co on the left and right sides facing each other at the position P in FIG. 2 are used for traveling on the rails Ri and Ro. Therefore, the holding tool Ci which runs on the rail Ri side (in-course side) becomes a positional position which precedes with respect to the holding tool Co which runs on the rail Ro side (out-course side). That is, one of the holding tools Ci and Co among the holding tools Ci and Co facing each other in a direction substantially perpendicular to the feeding direction D1 of the film at the position P in the drawing, the position Q at the end of the stretching of the film. ), The straight line which connected holding tools Ci and Co inclines by the angle (theta) L with respect to the direction substantially perpendicular to the winding-up direction D2 of a film. By the above operation, the film-like article is diagonally stretched at an angle of? L with respect to the width direction. In addition, substantially vertical means that it exists in the range of 90 +/- 1 degree.

Then, when it reaches | attains the exit part (position of Q in drawing) at the time of completion | finish of extending | stretching, the gripped film is opened. The film opened from the holding tools Ci and Co is wound up by the winding core by the winding part 17 mentioned above. The pair of rails Ri and Ro each have an endless continuous trajectory, and the gripping tools Ci and Co, which open the gripping of the film at the outlet of the tenter, sequentially drive the outer rails to enter the inlet. To return to wealth.

3. Use of λ / 4 retardation film

(Lambda) / 4 phase (s) difference film of this invention can be used suitably for a circularly polarizing plate and the organic electroluminescence display which has it as mentioned above.

Circular Polarizer

The circular polarizing plate of this invention contains a polarizer and (lambda) / 4 phase (s) difference film of this invention.

A polarizer is an element which passes only the light of the polarization plane of a fixed direction, and the typical polarizer currently known is a polyvinyl alcohol-type polarizing film. In the polyvinyl alcohol polarizing film, there are those obtained by dyeing iodine on a polyvinyl alcohol-based film and dyeing a dichroic dye.

The polyvinyl alcohol polarizing film may be a film uniaxially stretched from a polyvinyl alcohol-based film and then dyed with iodine or a dichroic dye (preferably a film further subjected to durability treatment with a boron compound); After dyeing a polyvinyl alcohol-type film with iodine or a dichroic dye, the film uniaxially stretched (preferably the film which further performed the durability treatment with a boron compound) may be sufficient. The absorption axis of the polarizer is usually parallel to the maximum stretching direction.

It is preferable that the thickness of a polarizer is 5-30 micrometers, and it is more preferable that it is 5-20 micrometers in order to thin a polarizing plate.

It is preferable that it is 40-50 degrees, and, as for the angle which the polarizer and the in-plane slow axis of (lambda) / 4 phase (s) difference film of this invention make, it is more preferable that it is 45 degrees.

When (lambda) / 4 phase (s) difference film of this invention is arrange | positioned only on one surface of a polarizer, a protective film may be arrange | positioned on the other surface. Examples of protective films include commercially available cellulose acylate films (for example, Konica Minolta Tak KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC8UY). -HA, KC8UX-RHA, KC8UE, KC4UE, KC4HR-1, KC4KR-1, KC4UA, KC6UA or more Konica Minolta Opto Co., Ltd. product, etc. are contained.

A circularly polarizing plate can be obtained by bonding a polarizer and (lambda) / 4 phase (s) difference film of this invention through an adhesive agent. As the adhesive, a fully saponified polyvinyl alcohol aqueous solution (water pool) or an active energy ray-curable adhesive agent can be used, and preferably a fully saponified polyvinyl alcohol aqueous solution (water pool) can be used.

Before bonding a (lambda) / 4 phase (s) difference film to one surface of a polarizer, it is preferable to further pre-process a (lambda) / 4 phase (s) difference film. That is, after pretreating the surface of (lambda) / 4 phase (s) difference film, it is preferable to bond together at least one surface of a polarizer through a polyvinyl alcohol-type adhesive agent. Examples of the pretreatment include saponification treatment, corona treatment, plasma treatment, and the like.

Since the lambda / 4 phase difference film of the present invention contains a cellulose ether derivative having an aromatic containing group, it is considered that the hydrogen atom added to the aromatic ring is likely to be activated by corona treatment from the relationship between the electronegativity of the aromatic ring and the covalent state of the electron. . On the other hand, since an aromatic ring shows hydrophobicity, it is hard to be affected by saponification. Thus, when the contact angle after a corona treatment and the contact angle after a saponification process of a (lambda) / 4 phase (s) difference film are compared, when the contact angle after a corona treatment is small 10 degrees or more, performing a corona treatment (not a saponification process) as a pretreatment is performed. desirable.

Based on JIS-R3257, 3 microliters of water were dripped at the temperature of 23 degreeC, and 55% of a relative humidity based on JIS-R3257, and contact angle meter DM300 (Kyowa Kaimen Kagaku) was used for the contact angle 1 minute after dripping of this drop. Can be measured.

<Organic EL display device>

The organic EL display device 100 of the present invention includes an organic EL element 110 and a circular polarizing plate 120.

3 is a schematic diagram illustrating an example of the configuration of the organic EL display device 100. As shown in FIG. 3, the organic EL display device 100 includes an organic EL element 110 and a circular polarizing plate 120.

The organic EL element 110 includes a metal electrode 112, a TFT 113, an organic light emitting layer 114, a transparent electrode (ITO, etc.) 115 in order on a transparent substrate 111 made of glass, polyimide, or the like. The insulating layer 116, the sealing layer 117, and the film 118 (can be omitted) are provided.

The metal electrode 112 functions as a cathode, and is made of a material having a small work function, for example, metal such as Mg-Ag or Al-Li, in order to facilitate electron injection and increase luminous efficiency.

The organic light emitting layer 114 is a laminate of various thin film organic functional layers, for example, a hole injection layer containing a triphenylamine derivative or the like and a laminate of a light emitting layer containing a fluorescent organic solid such as anthracene, or It may be a laminate of electron injection layers including such a light emitting layer and a perylene derivative, or a laminate of various combinations, such as a laminate of hole injection layers, light emitting layers, and electron injection layers thereof.

The transparent electrode 115 is a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO), and functions as an anode. As described above, in the organic EL display device, at least one electrode is made transparent in order to extract light from the organic light emitting layer.

The thickness of the organic EL element 110 is about 1 μm.

In such an organic EL display device, by applying a voltage to the transparent electrode 115 and the metal electrode 112, holes and electrons are injected into the organic light emitting layer 114, and energy generated by recombination of these holes and electrons is fluorescent. The material is excited and emits light by emitting light when the excited fluorescent material returns to the ground state.

The circularly polarizing plate 120 includes the polarizer 121, the λ / 4 retardation film 122 of the present invention disposed on the surface of the polarizer 121 on the organic EL element 110 side, and the organic EL of the polarizer 121. It has the protective film 123 arrange | positioned at the surface on the opposite side to the element 110. As shown in FIG. The hardening layer 124 and the antireflection layer 125 may further be laminated | stacked on the protective film 123 as needed. The cured layer 124 not only prevents scratches on the surface of the organic EL display device, but also has an effect of preventing warping by a long circular polarizing plate.

The screen size of the organic EL display device 100 may be, for example, a large screen of 20 inches or more, that is, a diagonal distance of 50.8 cm or more.

In the organic EL display device 100 configured as described above, the organic light emitting layer 114 is formed of a very thin film having a layer thickness of about 10 nm. Therefore, the organic light emitting layer 114, like the transparent electrode 115, transmits light almost completely. As a result, the light incident from the surface of the circular polarizing plate 120 at the time of non-luminescence, and transmitted through the transparent electrode 115 and the organic light emitting layer 114 and reflected by the metal electrode 112 again causes the circular polarizing plate 120 to be removed. Since it comes out to the surface side, when visually recognized from the outside, the display surface of the organic electroluminescence display 100 is observed like a mirror surface.

The circularly polarizing plate 120 including the λ / 4 retardation film 122 has a function of polarizing light incident from the outside and reflected by the metal electrode 112, specifically, the λ / 4 retardation film 122 and the polarizer. By setting the angle formed by the polarization direction of 121 to 45 °, the mirror surface of the metal electrode 112 can be almost completely shielded, and the mirror surface of the metal electrode 112 can be prevented from being visually recognized from the outside.

That is, only the linearly polarized light component transmits external light incident on the organic EL display device 100 by the polarizer, and the linearly polarized light is circularly polarized by the λ / 4 retardation film 122. The circularly polarized light passes through the film 118, the sealing layer 117, the insulating layer 116, the transparent electrode 115, and the organic light emitting layer 114, is reflected by the metal electrode 112, and then the organic light emitting layer ( 114, the transparent electrode 115, the insulating layer 116, the sealing layer 117, and the film 118 are transmitted, and linearly polarized light again in the λ / 4 retardation film 122. And since this linearly polarized light is orthogonal to the polarization direction of the polarizer 121, it cannot pass through the polarizer 121. As a result, the mirror surface of the metal electrode 112 can be shielded completely. Therefore, the organic EL display device can prevent projection of external light during viewing and can improve black displayability.

Example

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these.

1. film material

(1) Synthesis of Cellulose Ether Derivative / Lignin Derivative Mixture

<Synthesis of cellulose ether derivative / lignin derivative mixture 1>

In a vessel equipped with a stirring device, a thermometer, a cooling tube, and a dropping funnel, 50 parts by mass of cellulose ether derivative 1 (cellulose ether formed with a mixture of lignin derivatives) having an ethoxy group substitution degree of 2.35 obtained from the pulp material and a pyridine 1000 Each mass part was added, and it stirred at room temperature. 150 mass parts benzoyl chloride was dripped slowly here, and it stirred further at 80 degreeC for 7 hours. After the reaction, the mixture was left to cool until returning to room temperature, and the reaction solution was added with vigorous stirring to 1500 parts by mass of methanol to precipitate white solid.

The white solid was separated by filtration by suction filtration, washed with a large amount of methanol, dried overnight at 60 ° C., and then vacuum dried at 90 ° C. for 6 hours.

In a container equipped with a stirring device and a thermometer, 50 parts by mass of the white solid after washing and drying, 600 parts by mass of acetone and 500 parts by mass of methanol were added, respectively, stirred at 70 ° C and dissolved. The solution was poured with vigorous stirring in a mixed solvent of 7000 parts by mass of methanol and 4000 parts by mass of water to precipitate a white solid. The white solid was separated by filtration by suction filtration, and the obtained white solid was dried at 60 ° C for 12 hours, and then vacuum dried at 90 ° C for 6 hours. The same operation was repeated once more to give cellulose ether derivative / lignin derivative mixture 1 (mixture containing cellulose ether derivative 1 and lignin derivative).

The resulting cellulose ether derivative / lignin derivative mixture of cellulose with respect to a substituent of the glucose backbone of the ether derivative Figure 1, ¹ H-NMR and ¹³ results as measured by C-NMR, and determined its mean value, an aromatic-containing group contained in one The degree of substitution of the benzoate group was 0.65, the degree of substitution of the ethoxy group was 2.35, and the total degree of substitution was 3.00.

<Synthesis of cellulose ether derivative / lignin derivative mixtures 2 to 11>

In the synthesis of the cellulose ether derivative / lignin derivative mixture 1, the cellulose ether derivative / lignin derivative mixture 2 to 11 was similarly applied except that the reaction conditions were changed such that the ethoxy substitution degree and the benzoate substitution degree were the values shown in Table 1. (A mixture containing cellulose ether derivatives 2 to 11 and lignin derivatives) was obtained.

<Synthesis of cellulose ether derivative / lignin derivative mixture 12>

In a vessel equipped with a stirring device, a thermometer, a cooling tube, and a dropping funnel, 50 parts by mass of cellulose ether (cellulose ether formed with a mixture of lignin derivatives) having an ethoxy group substitution degree of 2.35 obtained from the pulp material and 1000 parts by mass of pyridine Each was added and stirred at room temperature. 160 mass parts of thiophene-2-carbonyl chlorides were dripped slowly here, and it stirred at 80 degreeC for 8 hours further. After the reaction, the mixture was left to cool until returning to room temperature, and the reaction solution was added with vigorous stirring to 1500 parts by mass of methanol to precipitate white solid.

The white solid was separated by filtration by suction filtration, washed with a large amount of methanol, dried overnight at 60 ° C., and then vacuum dried at 90 ° C. for 6 hours.

In a container equipped with a stirring device and a thermometer, 50 parts by mass of the white solid after washing and drying, 600 parts by mass of acetone and 500 parts by mass of methanol were added, respectively, stirred at 70 ° C and dissolved. The solution was poured with vigorous stirring in a mixed solvent of 7000 parts by mass of methanol and 4000 parts by mass of water to precipitate a white solid. The white solid was separated by filtration by suction filtration, and the obtained white solid was dried at 60 ° C for 12 hours, and then vacuum dried at 90 ° C for 6 hours. The same operation was repeated once more to obtain cellulose ether derivative / lignin derivative mixture 12 (mixture comprising cellulose ether derivative 12 and lignin derivative).

The resulting cellulose ether derivative / with respect to a substituent of the glucose backbone of the cellulose ether derivative 12 also included in the lignin derivative mixture 12, and measured by ¹ H-NMR and ¹³ C-NMR, was obtained his mean value, an aromatic-containing group The degree of substitution of the thiophene-2-carboxylate group was 0.65, the degree of substitution of the ethoxy group was 2.35, and the total degree of substitution was 3.00.

<Synthesis of cellulose ether derivative / lignin derivative mixture 13>

In a vessel equipped with a stirring device, a thermometer, a cooling tube, and a dropping funnel, 50 parts by mass of cellulose ether (cellulose ether formed with a mixture of lignin derivatives) having an ethoxy group substitution degree of 2.35 obtained from the pulp material and 1000 parts by mass of pyridine Each was added and stirred at room temperature. After 160 mass parts of 2-naphthoyl chloride was dripped slowly here, it stirred further at 80 degreeC for 8 hours. After the reaction, the mixture was left to cool until returning to room temperature, and the reaction solution was added with vigorous stirring to 1500 parts by mass of methanol to precipitate white solid.

The white solid was separated by filtration by suction filtration, washed with a large amount of methanol, dried overnight at 60 ° C., and then vacuum dried at 90 ° C. for 6 hours.

In a container equipped with a stirring device and a thermometer, 50 parts by mass of the white solid after washing and drying, 600 parts by mass of acetone and 500 parts by mass of methanol were added, respectively, stirred at 70 ° C and dissolved. The melt was poured into 7000 parts by mass of methanol and 4000 parts by mass of mixed solvent with vigorous stirring to precipitate a white solid. The white solid was separated by filtration by suction filtration, and the obtained white solid was dried at 60 ° C for 12 hours, and then vacuum dried at 90 ° C for 6 hours. The same operation was repeated once more to give cellulose ether derivative / lignin derivative mixture 13 (mixture containing cellulose ether derivative 13 and lignin derivative).

About the substitution degree of the substituent of the glucose skeleton of the cellulose ether derivative 13 contained in the obtained cellulose ether derivative / lignin derivative mixture 13, it measured by ¹ H-NMR and ¹³ C-NMR, and calculated | required the average value, and it is an aromatic containing group The degree of substitution of the 2-naphthoate group was 0.65, the degree of substitution of the ethoxy group was 2.35, and the total degree of substitution was 3.00.

<Synthesis of cellulose ether derivative / lignin derivative mixture 14>

In the synthesis of the cellulose ether derivative / lignin derivative mixture 1, the reaction solution was allowed to cool until it returned to room temperature, and then 3 parts by mass of lignin (dealkali) (manufactured by Tokyo Kasei Kogyo KK) was added. The cellulose ether derivative / lignin derivative mixture 14 (mixture containing a cellulose ether derivative and a lignin derivative) was obtained.

(2) Preparation of a composition comprising a cellulose ether derivative / lignin derivative mixture and an acid or salt thereof

<Production of Compositions 1 and 16 to 27>

50 mass parts of cellulose ether derivative / lignin derivative mixture 1, 600 mass parts of acetone, and 500 mass parts of methanol were added to the container equipped with the stirring apparatus and the thermometer, and it stirred at 70 degreeC, and dissolved.

When the solution was added to the mixed solvent in which 7000 parts by mass of methanol, 4000 parts by mass of water and the acid shown in Table 1 were added to the amount shown in Table 1 with respect to the cellulose ether derivative, the white solid was added. Precipitated. The white solid was separated by filtration by suction filtration, and the obtained white solid was dried at 60 ° C. for 12 hours, and then vacuum dried at 90 ° C. for 6 hours to form a composition comprising the cellulose ether derivative / lignin derivative mixture 1 and the acid shown in Table 1. 1 and 16 to 27 were obtained, respectively.

<Production of Composition 2>

In the production of the composition 1, the cellulose ether derivative / lignin derivative mixture 1 is changed to cellulose ether derivative / lignin derivative mixture 0 containing cellulose ether derivative 0 having a degree of substitution of 2.35 ethoxy group before reacting with benzoate A composition 2 containing a cellulose ether derivative / lignin derivative mixture 0 and benzoic acid was obtained in the same manner except for the above.

<Production of Compositions 3 to 12>

50 mass parts of cellulose ether derivative / lignin derivative mixture 2, 600 mass parts of acetone, and 500 mass parts of methanol were added to the container equipped with the stirring apparatus and the thermometer, and it stirred at 70 degreeC, and dissolved.

A white solid precipitated when the solution was added to a mixed solvent in which 7000 parts by mass of methanol, 4000 parts by mass of water and the acid shown in Table 1 were added to the amount shown in Table 1 with respect to the cellulose ether derivative. It became. The white solid was separated by filtration by suction filtration, and the obtained white solid was dried at 60 ° C. for 12 hours, and then vacuum dried at 90 ° C. for 6 hours to obtain a composition 3 containing a cellulose ether derivative / lignin derivative mixture 2 and benzoic acid.

The same operation was performed also about the cellulose ether derivative / lignin derivative mixture 3-11, and the compositions 4-12 containing the cellulose ether derivative / lignin derivative mixture 3-11 and benzoic acid were obtained, respectively.

<Production of Compositions 13 to 14>

50 mass parts of cellulose ether derivative / lignin derivative mixture 12, 600 mass parts of acetone, and 500 mass parts of methanol were added to the container equipped with the stirring apparatus and the thermometer, and it stirred at 70 degreeC, and dissolved.

A white solid precipitated when the solution was added to a mixed solvent in which 7000 parts by mass of methanol, 4000 parts by mass of water and the acid shown in Table 1 were added to the amount shown in Table 1 with respect to the cellulose ether derivative. It became. The white solid was separated by filtration by suction filtration, and the obtained white solid was dried at 60 ° C. for 12 hours, and then vacuum dried at 90 ° C. for 6 hours to include the cellulose ether derivative / lignin derivative mixture 13-14 and the acid shown in Table 1. Compositions 13 to 14 were obtained, respectively.

<Production of Composition 15>

50 mass parts of cellulose ether derivative / lignin derivative mixture 13, 600 mass parts of acetone, and 500 mass parts of methanol were added to the container equipped with the stirring apparatus and the thermometer, and it stirred at 70 degreeC, and dissolved.

A white solid precipitated when the solution was added to a mixed solvent in which 7000 parts by mass of methanol, 4000 parts by mass of water and the acid shown in Table 1 were added to the amount shown in Table 1 with respect to the cellulose ether derivative. It became. The white solid was separated by filtration by suction filtration, and the obtained white solid was dried at 60 ° C. for 12 hours and then vacuum dried at 90 ° C. for 6 hours to obtain a composition 15 containing a mixture of cellulose ether derivative 13 / lignin derivatives and naphthoic acid. .

<Production of Composition 28>

50 mass parts of cellulose ether derivative / lignin derivative mixture 14, 600 mass parts of acetone, and 500 mass parts of methanol were added to the container equipped with the stirring apparatus and the thermometer, and it stirred at 70 degreeC, and dissolved.

A white solid precipitated when the solution was added to a mixed solvent in which 7000 parts by mass of methanol, 4000 parts by mass of water and the acid shown in Table 1 were added to the amount shown in Table 1 with respect to the cellulose ether derivative. It became. The white solid was separated by filtration by suction filtration, and the obtained white solid was dried at 60 ° C. for 12 hours, and then vacuum dried at 90 ° C. for 6 hours to obtain a composition 28 comprising a cellulose ether derivative / lignin derivative mixture 14 and benzoic acid.

(3) additive

C-1: adecas staff AO-60 (made by ADEKA, phenolic antioxidant)

C-2: ADEKA STAB PEP-36 (made by ADEKA, phosphite antioxidant)

C-3: SUMILIZER GP (product made in Sumitomo Chemical Industries, Ltd., processing stabilizer)

C-4: IRGANOX 1010 (made by BASF Japan, Hindered phenolic antioxidant)

C-5: Adecastab LA-31 (manufactured by ADEKA, 2,2'-methylenebis [6- (2-benzotriazolyl) -4- (1,1,3,3-tetramethylbutyl)) Phenol], hindered amine light stabilizer)

C-6: TINUVIN 928 (made by BASF Japan, the benzotriazole type ultraviolet absorber)

2. Preparation of λ / 4 Retardation Film

<Production of λ / 4 Retardation Film 1>

(Production of Particulate Addition Liquid)

Aerosil R812 (Matt, made by Nisbon Aerosil Co., Ltd.): 4 parts by mass

Dichloromethane: 48 parts by mass

Ethanol: 48 parts by mass

Each of the constituent materials described above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with a manton Gaulin. This was filtered by Nippon Seisen Co., Ltd. FineMet NF, and the microparticles | fine-particles addition liquid whose mat agent content is 4.0 mass% was manufactured.

(Manufacture of dope 1)

Using composition 1 prepared above, dope 1 of the following composition was produced.

First, dichloromethane and ethanol were put into a pressure dissolution tank. Subsequently, the composition 1 was poured into the pressure dissolution tank while stirring so that the content of the cellulose ether derivative 1 was 100 parts by mass. Subsequently, 15 minutes after the composition 1 was added, the prepared fine particle addition liquid was added, heated to 80 ° C, and completely dissolved while stirring. Heating temperature heated up at 5 degree-C / min from room temperature, melt | dissolved for 30 minutes, and then heated up to 35 degreeC at 3 degree-C / min.

This was filtered by the filtration flow rate of 300 L / m <^2> h and the filtration pressure of 1.0x10 <^6> Pa using Azumi Rossi No.244 (filtration accuracy 0.005mm) by Azumi Rossi Co., Ltd., and dope 1 was manufactured.

(The composition of dope 1)

Cellulose ether derivative 1: 100.0 parts by mass

Lignin derivative: 0.1 parts by mass

Benzoic acid: 5 mass ppm per cellulose ether derivative 1

Dichloromethane: 1000.0 parts by mass

Ethanol: 150.0 parts by mass

Fine particle addition liquid: 2.5 parts by mass

(Production)

The dope 1 prepared above was fed from the pressure dissolution tank to the pressure die by a gear pump, and cast (cast) on an endless support (belt) made of stainless steel.

The solvent was evaporated until the amount of residual solvent in the flexible web was 40 mass%, and then the web was peeled off at a peel tension of 130 N / m from the stainless endless support.

While peeling the web, it extended | stretched by 100% of elongation in the diagonal direction (45 degree direction with respect to the width direction) using the diagonal stretch apparatus as shown in FIG. At this time, drying conditions from peeling to a tenter were adjusted so that the amount of residual solvent at the time of extending | stretching may be 11 mass%. In addition, the temperature of the tenter stretching apparatus was 160 degreeC, and the extending | stretching speed was 200% / min.

Next, drying was complete | finished, conveying the inside of a drying apparatus with many rollers. Drying temperature was 130 degreeC, and conveyance tension was 100 N / m. Both ends of the film obtained by drying were slit by the slit apparatus which has a rotary tooth, and the (lambda) / 4 phase (s) difference film 1 of width 1000mm and film thickness 50micrometer was produced.

<Production of λ / 4 Retardation Films 2, 4 to 13, and 35>

(Lambda) / 4 phase (s) difference films 2, 4-13, and 35 were obtained like (lambda) / 4 phase (s) difference film 1 except having changed the cellulose ether derivative to what is shown in Table 1 using the composition 2-12 and 28.

<Production of λ / 4 Retardation Films 14 to 22>

(Lambda) / 4 phase (s) difference film 14-22 was obtained like (lambda) / 4 phase (s) difference film 1 except having changed the at least one of a cellulose ether derivative and an acid to what was shown in Table 1 using compositions 13-21.

<Production of λ / 4 Retardation Films 23 to 28>

(Lambda) / 4 phase (s) difference film 23-28 were obtained like the (lambda) / 4 phase (s) difference film 1 except having changed the content of acid as shown in Table 1 using the composition 22-27.

<Production of λ / 4 Retardation Films 29 to 34>

(Lambda) / 4 phase (s) difference films 29-34 were obtained like the (lambda) / 4 phase (s) difference film 1 except having used the composition 19 and further adding the additive of the kind and quantity shown in Table 1.

<Production of λ / 4 Retardation Films 3 and 36>

(Lambda) / 4 phase (s) difference films 3 and 36 were obtained similarly to (lambda) / 4 phase (s) difference films 1 and 35 except having used the cellulose ether derivative / lignin derivative mixture 1 or 14, and without adding an acid.

The number of bubbles, YI, haze, retardation Ro, and wavelength dispersion | distribution (DSP) of the obtained (lambda) / 4 phase (s) difference films 1-36 were evaluated with the following method, respectively.

[bubble]

(lambda) / 4 phase (s) retardation film was put on the black velvet cloth, and the presence or absence of the bubble was confirmed visually under the illumination of fluorescent lamp. 100m was observed in the longitudinal direction of (lambda) / 4 phase (s) difference film, and the number of bubbles was measured.

When the number of bubbles is 20 or more, since the yield falls when the polarizing plate is produced using this film, it was judged that 30 or less was good and less than 20 was more favorable.

[YI]

(Early)

The yellow index (YI) of the lambda / 4 phase difference film was measured by the method described in JIS K-7105-6.3. As a specific method of measuring the yellow index value, the tristimulus values X, Y, and Z of the color were measured using a spectrophotometer U-3200 manufactured by Hitachi High Technology Co., Ltd. and the accompanying chroma calculation program. The obtained value was applied to the following formula, and the yellow index value was computed.

Yellow index (YI) = 100 (1.28X-1.06Z) / Y

It was judged that yellow index (YI) was satisfactory if it was 1.5 or less, and more favorable if it was less than 1.2 (transparency was high and it is especially preferable as (lambda) / 4 phase (s) difference film).

(After flash)

(lambda) / 4 phase (s) difference film was cut into the size of 100 mm x 100 mm. This film was irradiated with light for 300 hours at an intensity of 60 W / m ² in accordance with ISO4292-2 using an atlas weather meter Ci3000 + (manufactured by Atlas) as a xenon weather meter. About the film after irradiation, 25 points of 5x5 and YI were measured in 20 mm space | interval, and the difference between the maximum value and the minimum value was made into the value after (triangle | delta) YI light-proofing.

When the value after (DELTA) YI light tolerance is larger than 0.85, since the coloring nonuniformity generate | occur | produces in a film, display nonuniformity tends to arise when this film is used for an organic electroluminescence display. Therefore, it was judged that the value after (DELTA) II light tolerance was favorable if it was 0.85 or less, and it was still more favorable if it was less than 0.8.

[Haze]

The haze of (lambda) / 4 phase (s) difference film was measured using NDH-2000 (made by Nippon Denshoku Kogyo Co., Ltd.) based on JISK-7136. As a light source, the halogen bulb of 5V9W was used, and the light receiving part used the silicon photocell (with a non-sensitivity filter). The measurement was performed under the environment of a temperature of 23 ° C. and a relative humidity of 55%.

[In-plane retardation value (Ro)]

In-plane retardation value Ro in wavelength 550nm of (lambda) / 4 phase (s) difference film was measured using AxoScan by Axometrics company in the environment of the temperature of 23 degreeC, and 55% of the relative humidity.

Specifically, the three-dimensional refractive index at a wavelength of 550 nm of the λ / 4 retardation film was measured under an environment of 55 ° C.HH at 23 ° C., and the average values of the refractive indices nx, ny, and nz were obtained. The obtained value was applied to the following formula, and the in-plane phase difference value Ro was calculated.

Equation (1): Ro = (nx-ny) × d

In Formula (1), nx represents the refractive index in the direction x which becomes the largest in the in-plane direction of a film. ny represents the refractive index in the direction y orthogonal to the said direction x in the in-plane direction of a film. nz represents the refractive index in the thickness direction z of a film. d represents the thickness (nm) of a film.

Ro was good if it is 30-300 nm, and if it was 120-150 nm, it judged that it was still more favorable.

Wavelength Variance Value (DSP)

In-plane retardation value Ro in wavelength 450nm and 550nm of (lambda) / 4 phase (s) difference film was measured using Axoscan by Axometrics company in the environment of the temperature of 23 degreeC and 55% of relative humidity, respectively. The in-plane phase difference value Ro (450) in the obtained wavelength 450nm and the in-plane phase difference value Ro (550) in the wavelength 550nm were applied to the following formula, and the wavelength dispersion value DSP was computed.

Equation (3): DSP = Ro (450) / Ro (550)

It was judged that DSP was good if it was less than 1.0, and more than 0.75 and 0.9 or less.

In addition, about (lambda) / 4 phase (s) difference film 1, 20, and 23-34, the heat-resistant deterioration characteristic was further evaluated.

[Heat resistance deterioration]

(lambda) / 4 phase (s) difference film was hold | maintained for 300 hours in 90 degreeC environment. In-plane phase difference value Ro after 300 hours was measured, and the retention rate of phase difference was computed.

Phase difference retention rate (%) = Ro (after 300 hours) / Ro (initial value) × 100

Table 1 shows the evaluation results of the λ / 4 retardation films 1 to 36.

As shown in Table 1, it turns out that the (lambda) / 4 phase (s) difference film 1 and 4-35 of this invention all generate | occur | produce few bubbles in a film manufacturing process, and also show little coloration of a film. In addition, it is suggested that (lambda) / 4 phase difference films 1 and 4-35 of this invention can express (lambda) / 4 phase difference in broadband from the point that DSP is less than one.

In addition, by setting the degree of substitution of the aromatic-containing group of the cellulose ether derivative to be in the range of 0.1 to 1.0 and the degree of substitution of the ethoxy group to 1 to 2.5, the DSP is appropriately maintained while the in-plane retardation value Ro of the film obtained is appropriately increased. It can be seen that it can be made low (contrast of λ / 4 retardation film 4 to 13).

Moreover, it turns out that generation | occurrence | production of foam | bubble and coloring of a film can further be suppressed by using the acid containing an aromatic ring or its salt (relative of (lambda) / 4 phase (s) difference film 17-22).

In addition, retardation retention of (lambda) / 4 phase (s) difference film 1, 23, 24, 25, 26, 27, 28 was 98%, 99%, 98%, 98%, 97%, 96%, and 80%, respectively. Similarly, evaluation was also performed about lambda / 4 phase difference film 20, 29, 30, 31, 32, 33, 34, the retardation retention is 92%, 98%, 98%, 98%, 98%, 98%, 98%. Thus, it turned out that (lambda) / 4 phase (s) difference film of this invention has a high phase difference retention rate even after heat resistance.

On the other hand, it turns out that the comparative (lambda) / 4 phase (s) difference film 3 which does not contain an acid or its salt has many generation | occurrence | production of the bubble in a film manufacturing process, and also many coloring of a film. Moreover, DSP of 1 becomes the 1 of the comparative (lambda) / 4 phase (s) difference film 2 using the cellulose ether derivative 2 which does not have an aromatic containing group, and it is suggested that it is difficult to express (lambda) / 4 phase difference in broadband.

3. Preparation and Evaluation of Polarizer

<Measurement of Contact Angle of λ / 4 Retardation Film>

(Production of sample 1)

Corona discharge treatment was given to each of the lambda / 4 phase difference films 1 and 2 produced as described above, to obtain Sample 1. The conditions of corona discharge treatment were discharge gap: 0.5 mm, output: 14 kv, and processing speed of 50 m / min.

(Production of sample 2)

For each of the lambda / 4 phase difference films 1 and 2 produced above, saponification was performed for 90 seconds in 2N KOH heated at 50 ° C. Thereafter, the mixture was washed with water and dried to obtain Sample 2.

The contact angles of the treated surfaces of the obtained samples 1 and 2 were measured by the following methods, respectively.

(Measurement of contact angle)

Based on JIS-R3257, 3 microliters of water were dripped at the processed surface of the obtained sample in the atmosphere of 23 degreeC of temperature, and 55% of a relative humidity, and the contact angle after 1 minute of dripping of the drop was measured by the contact angle meter DM300 (Kyowa Gaimen Gaga). Measurement). And the value of the contact angle of the sample 1 and the contact angle of the sample 2 was applied to the following formula, and the difference of the contact angle was calculated | required.

Difference of contact angle = | contact angle of sample 2 (contact angle after saponification) -contact angle of sample 1 (contact angle after corona) |

The difference in contact angle between the lambda / 4 phase difference film 1 was 19 °, and the difference in contact angle between the lambda / 4 phase difference film 2 was 6 °. That is, it turned out that the difference of a contact angle is large in the (lambda) / 4 phase (s) difference film 1 side.

<Production of Polarizing Plate 1>

(Production of polarizer)

The polyvinyl alcohol film of thickness 120micrometer was uniaxially stretched (temperature 110 degreeC, draw ratio 5 times). This was immersed for 60 seconds in the aqueous solution containing 0.075g of iodine, 5g of potassium iodide, and 100g of water. Subsequently, it was immersed in the 68 degreeC aqueous solution 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.

(Production of adhesive)

After dissolving 10 parts by weight of Kosenex Z200 (manufactured by Nippon Kosei Chemical Co., Ltd.) at 250 parts by weight of pure water, 1 part by weight of Safelink SPM-01 (manufactured by Nippon Kosei Chemical Co., Ltd.) was added to obtain an adhesive.

(Production of Polarizing Plate 1)

The corona discharge treatment was given to the surface of the produced (lambda) / 4 phase (s) difference film 1. The conditions of corona discharge treatment were discharge gap: 0.5 mm, output: 14 kv, and processing speed of 50 m / min. Subsequently, on the corona discharge treatment surface of (lambda) / 4 phase (s) difference film 1, the adhesive prepared above was apply | coated with the bar coater so that the film thickness after drying might be set to about 0.5 micrometer, and the adhesive bond layer was formed. The polarizer produced above was bonded to the obtained adhesive bond layer. Bonding was performed so that the angle which the in-plane slow axis of (lambda) / 4 phase (s) difference film 1 and the absorption axis of a polarizer make may be 45 degrees.

In addition, the protective film (Konica Minolta Tak KC2UA, thickness 25micrometer, the product made by Konica Minolta Co., Ltd.) was washed with water after saponification for 90 second in 2N KOH heated at 50 degreeC. On the saponification process surface of the obtained protective film, the adhesive liquid prepared above was apply | coated with the bar coater so that the film thickness after drying might be about 0.5 micrometer, and the adhesive bond layer was formed. And the protective film with an adhesive bond layer was bonded with the polarizer to which the produced (lambda) / 4 phase (s) difference film 1 was bonded, and the laminated body which laminated | stacked (lambda) / 4 phase (s) difference film 1 / adhesive layer / polarizer / adhesive layer / protective film was laminated | stacked. Got it. This laminated body was dried at 60 degreeC for 10 minutes, and the polarizing plate 1 was produced.

<Production of Polarizing Plate 2>

The polarizing plate 2 was produced like manufacture of the polarizing plate 1 except having changed (lambda) / 4 phase (s) difference film 1 into (lambda) / 4 phase (s) difference film (2).

The adhesiveness of (lambda) / 4 phase (s) difference film and a polarizer was evaluated whether the (lambda) / 4 phase (s) difference film of the obtained polarizing plates 1 and 2 could be peeled by hand from a polarizer. As a result, it was found that the polarizing plate 1 could not be peeled by hand with the λ / 4 retardation film 1, and the adhesiveness between the polarizer and the λ / 4 retardation film 1 was high. On the other hand, the polarizing plate 2 can peel by hand only (lambda) / 4 phase (s) difference film 2, and it turned out that the adhesiveness of a polarizer and (lambda) / 4 phase (s) difference film 2 is not enough.

This application claims the priority based on Japanese Patent Application No. 2017-049115 for which it applied on March 14, 2017. All the content described in the said application specification and drawing is integrated in this specification.

According to this invention, it is a (lambda) / 4 phase (s) retardation film containing a cellulose ether derivative and a lignin derivative, there can be provided the broadband (lambda) / 4 phase (s) retardation film with few defect sites resulting from foaming at the time of solution film forming, and suppressing coloring.

10: tilt stretching device
11: vice
12: conveying direction changing part
13: guide roll
14: drawing part
15: guide roll
16: conveying direction changing part
17: winding
100: organic EL display device
110: organic EL device
111: transparent substrate
112: metal electrode
113: TFT
114: organic light emitting layer
115: transparent electrode (ITO, etc.)
116: insulation layer
117: sealing layer
118: film
120: circularly polarizing plate
121: polarizer
122: lambda / 4 phase difference film
123: protective film
124: hardened layer
125: antireflection layer

Claims (7)

(Lambda) / 4 phase (s) difference film containing the cellulose ether derivative which has an aromatic containing group, a lignin derivative, and an acid or its salt. The alkoxy group included in the cellulose ether derivative is an aliphatic alkoxy group,
The aromatic containing group is an aromatic acylate group, and
(Lambda) / 4 phase (s) difference film with which the said cellulose ether derivative satisfy | fills following formula (I).
Formula (I): 1.5≤X + Y≤3.0
1.0≤X≤2.5
0.1≤Y≤1.0
(In formula (I),
X is a degree of substitution of the aliphatic alkoxy group,
Y is a substitution degree of the said aromatic acylate group) The lambda / 4 phase difference film according to claim 1 or 2, wherein the acid is an organic acid having an aromatic ring. (Lambda) / 4 phase (s) difference film as described in any one of Claims 1-3 whose content of the said acid or its salt is 0.5-500 mass ppm with respect to the total mass of the said cellulose ether derivative. The lambda / 4 phase difference film according to any one of claims 1 to 4, further comprising one or more additives selected from the group consisting of phenolic compounds, phosphite compounds and benzotriazole compounds. It contains a polarizer and (lambda) / 4 phase (s) difference film as described in any one of Claims 1-5,
The circularly-polarizing plate whose angle which the in-plane slow axis of the (lambda) / 4 phase (s) difference film and the absorption axis of the said polarizer make is 40-50 degrees. An organic electroluminescence display containing an organic electroluminescent element and the circularly-polarizing plate of Claim 6.

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