TWI570463B - Polarizing plate, manufacturing method of polarizing plate, liquid crystal display device, and organic electroluminescent display device - Google Patents

Description

Polarizing plate, manufacturing method of polarizing plate, liquid crystal display device and organic electroluminescence display device

The present invention relates to a polarizing plate, a method of manufacturing the polarizing plate, a liquid crystal display device, and an organic electroluminescence display device. In particular, a polarizing plate having an optical film which is obliquely extended, a polarizing plate capable of suppressing occurrence of physical deformation, a method of manufacturing such a polarizing plate, a liquid crystal display device including the polarizing plate, and an organic electroluminescence display device.

In recent years, the market for thin displays using liquid crystal displays or organic electroluminescence has grown rapidly. In particular, the market for small and medium-sized portable devices, known as smart phones or tablets, has grown significantly.

This thin display is equipped with a polarizing plate. The polarizing plate generally adopts a configuration in which two optical films are attached to the polarizing mirror.

In the method of producing a polarizing plate, for example, a technique of manufacturing a polarizing mirror and a bonded circular polarizing plate by a roll-to-roll method using an optical film extending in the oblique direction with respect to the width direction is proposed (see, for example, Patent Document 1). The optical film is extended in the oblique direction at a specific angle with respect to the width direction (hereinafter also referred to as "inclined extension") to impart a desired phase difference. Although such an optical film is preferably a polycarbonate or a cycloolefin resin, a cellulose ester resin is also proposed (see, for example, Patent Document 2).

However, when the above-described obliquely extending optical film is laminated on a polarizing mirror to form a polarizing plate, the polarizing plate may be physically deformed due to the use environment of the polarizing plate. When the polarizing plate is physically deformed, the display device or the like on which the polarizing plate is mounted may be physically deformed, which is not preferable.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2006-224618

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-83307

[Summary of the Invention]

The present invention has been made in view of the above problems, and a problem is to provide a polarizing plate including an optical film which is obliquely extended, and a polarizing plate capable of suppressing occurrence of physical deformation, and a method for producing the polarizing plate. A liquid crystal display device and an organic electroluminescence display device of the polarizing plate.

In order to solve the above problems of the present invention, the above research is carefully studied. As a result of the problem, etc., it has been found that a polarizer having a polarizer and a first optical film disposed on one surface of the polarizer and a second optical film disposed on the other surface of the polarizer is provided. The angle between the slow axis of the first optical film and the absorption axis of the polarizer is in the range of 30 to 60°, and the dimensional change rate L(θ) of the slow axis direction of the first optical film and the slow axis are positive. The dimensional change rate L (θ + 90) in the direction of intersection is adjusted to a specific numerical range, and a polarizing plate which suppresses the occurrence of physical deformation can be provided.

That is, the subject of the present invention is solved by the following means.

A polarizing plate comprising a polarizing mirror, a first optical film facing one of the polarizing mirrors, and a polarizing plate of a second optical film facing the other of the polarizing mirrors, the first 1 The angle θ between the slow axis of the optical film and the absorption axis of the polarizer is in the range of 30 to 60°, and the dimensional change rate L(θ) of the slow axis direction of the first optical film and the direction orthogonal to the slow axis The dimensional change rate L (θ + 90) is adjusted to satisfy the following formulas (1) and (2): Formula (1): 0.50 ≦ L (θ) / L (θ + 90) ≦ 0.95

Formula (2): 0.1 (%) ≦ L (θ) ≦ 1.5 (%).

2. The polarizing plate according to the first aspect, wherein the dimensional change ratio L (MD) in the longitudinal direction of the first optical film and the dimensional change ratio L (TD) in the width direction satisfy the following In the formula (3), the formula (3): 0.50 ≦ L (MD) / L (TD) < 1.00.

3. The polarizing plate according to Item 1, wherein the first optical film contains a polymer having a cellulose skeleton.

4. The polarizing plate according to the first aspect, wherein the first optical film has a retardation value Ro (550) in the in-plane direction of a wavelength of 550 nm of 75 to 150 nm.

5. The polarizing plate according to Item 1, wherein the first optical film contains cellulose acetate propionate.

6. The polarizing plate according to Item 1, wherein the slow axis of the second optical film is parallel or orthogonal to the absorption axis of the polarizer.

7. The polarizing plate according to item 1, wherein the second optical film contains cellulose acetate or cellulose acetate propionate.

8. The polarizing plate according to the first aspect, wherein the first optical film and the second optical film are disposed on a side of the identification side of the optical film on the identification side, and a hardened layer or an anti-glare layer is provided.

A method of producing a polarizing plate, comprising: the polarizing mirror, the first optical film, and the second optical film, in a method of producing a polarizing plate according to any one of the items 1 to 8. A lamination step that is applied in a roll-to-roll manner.

10. The method for producing a polarizing plate according to the above item 9, further comprising the step of casting a dope onto the support to form a casting step of casting a film, and the residual solvent amount is 1 to 20 The above-mentioned cast film of % by mass is extended in the width direction by a stretching ratio of 1.01 to 1.3 times. a step of extending the cast film in the oblique direction with respect to the width direction, and performing the heat treatment of (i) or (ii) on the cast film to obtain the first optical a heat treatment step of the film, after the heat treatment step, performing the bonding step, and (i) performing embossing on the end portion of the cast film in the range of 180 to 220 ° C, and winding the film into a roll In a state of 60 to 80 ° C and 20% RH or less, heat treatment is performed for 3 to 5 days, (ii) the casting film is conveyed at a tension of 120 to 150 N by a conveying roller, and the conveying roller is passed through the conveying roller. The cast film is heat treated at 140 to 170 ° C for 40 to 600 seconds.

A liquid crystal display device comprising the polarizing plate according to any one of items 1 to 8 above.

An organic electroluminescence display device comprising the polarizing plate according to any one of items 1 to 8 above.

According to the present invention, it is possible to provide a polarizing plate having an optical film which is obliquely extended, a polarizing plate which can suppress the occurrence of physical deformation, a method of manufacturing such a polarizing plate, a liquid crystal display device including the polarizing plate, and an organic electro-optical device. Light emitting display device.

The mechanism or mechanism for exhibiting the effects of the present invention is not clear, but can be estimated as follows.

In general, in the environment in which the optical film is used, for example, in a high-humidity environment, there is a case where the size changes due to moisture absorption. Here, in the case of obliquely extending the optical film, the dimensional change rate in the width direction or the longitudinal direction is different from the dimensional change rate in the oblique direction, and specifically, the dimensional change rate in the unextended direction (width direction or length direction) is larger than the extending direction. The rate of change in size. Such a characteristic is more likely to be seen on an optical film having a dimensional change rate in the extending direction of a certain degree or more, particularly in the case of obliquely extending at a high magnification. Such a difference in dimensional change rate in the direction of the surface of the optical film causes physical deformation of the polarizing plate.

Therefore, by making the dimensional change rate of the first optical film in the slow axis direction and the dimensional change rate in the direction orthogonal to the slow axis satisfy the above formulas (1) and (2), the surface direction of the first optical film can be reduced. The difference in dimensional change rate is to reduce the stress generated by the polarizing plate and to suppress physical deformation.

1‧‧‧ manufacturing equipment

2‧‧‧Film delivery department

3, 7‧‧‧Transfer Direction Change Department

4,6‧‧‧guide roller

5‧‧‧Extension

8‧‧‧Film cutting device

9‧‧‧ Film winding department

10‧‧‧Liquid crystal display device

11‧‧‧Liquid cell

12, 13, 52‧ ‧ polarizing plates

14‧‧‧ Backlight

15, 53‧‧‧ front panel

21, 31, 61‧‧‧ polarizer

22, 62‧‧‧1st optical film

23, 63‧‧‧ functional layer

24, 64‧‧‧2nd optical film

32, 33‧‧‧ Optical film

50‧‧‧Organic EL display device

51‧‧‧Organic EL light-emitting elements

Ci, Co‧‧‧ holding tools

D1‧‧‧Send direction

D2‧‧‧ winding direction

Ri, Ro‧‧ track

W, Wo‧‧ wide

Z1‧‧‧Preheating zone

Z2‧‧‧Extension

Z3‧‧‧Hot fixed area

θ i‧‧‧Send angle

θ L‧‧‧ angle

Fig. 1 is a schematic plan view showing a schematic configuration of a manufacturing apparatus of a first optical film used in a polarizing plate of the present invention.

Fig. 2 is a schematic plan view showing an example of a rail pattern of an extension portion of the manufacturing apparatus shown in Fig. 1.

Fig. 3 is a cross-sectional view showing the schematic configuration of a liquid crystal display device of the present invention.

Fig. 4 is a cross-sectional view showing the schematic configuration of an organic EL display device of the present invention.

[Formation of the Invention]

The polarizing plate of the present invention includes a polarizing mirror, a first optical film that faces one of the polarizing mirrors, and a polarizing plate that faces the second optical film that is disposed to face the other of the polarizing mirrors. 1 The angle θ between the slow axis of the optical film and the absorption axis of the polarizer is in the range of 30 to 60°, and the dimensional change rate L(θ) of the slow axis direction of the first optical film and the direction orthogonal to the slow axis The dimensional change rate L (θ + 90) is adjusted to satisfy the above formulas (1) and (2). This feature is a common or corresponding technical feature of each of the patent application scopes of the patent application scopes 1 to 12.

Further, in the present invention, it is preferable that the dimensional change ratio L (MD) in the longitudinal direction of the first optical film and the dimensional change ratio L (TD) in the width direction satisfy the above formula (3). Thereby, a polarizing plate in which the occurrence of a surface failure or a planar failure is suppressed can be formed.

Further, in the invention, it is preferred that the first optical film contains a polymer having a cellulose skeleton. Thereby, the planarity of the first optical film can be improved, and the planarity of the polarizing plate using the first optical film can be improved.

Further, in the present invention, the retardation value Ro (550) of the in-plane direction of the wavelength of 550 nm of the first optical film is in the range of 75 to 150 nm, and is preferable from the viewpoint of the visibility of the display device on which the polarizing plate is mounted. .

Further, in the present invention, the first optical film contains cellulose acetate propionate, and is preferable from the viewpoint of suppressing occurrence of physical deformation of the polarizing plate.

Further, in the present invention, the slow axis of the second optical film is parallel or orthogonal to the absorption axis of the polarizer, and is preferably a roll-to-roll type, which is inexpensive and has good planarity.

In the present invention, the second optical film contains cellulose acetate or cellulose acetate propionate, and the visibility of the optical security of the display device on which the polarizing plate is mounted is improved, and the planarity is ensured. Preferably. Further, these resin-based film thicknesses have a high phase difference exhibiting ratio, and a film having excellent visibility can be formed.

Further, in the present invention, it is preferable that the first optical film and the surface on the side of the identification side of the optical film on the side of the second optical film are provided with a hardened layer or an anti-glare layer (ANTIGLARE LAYER). When the hardened layer is provided, the surface of the polarizing plate can be protected, the anti-glare layer can be provided, the visibility of the reflected image can be reduced, and the reflection image can be suppressed.

Further, the method for producing a polarizing plate according to the present invention is the method for producing a polarizing plate, comprising a bonding step of bonding the polarizing mirror, the first optical film, and the second optical film in a roll-to-roll manner .

Furthermore, in the present invention, the method further comprises the steps of: casting a dope onto a support to form a casting film, and casting the cast film having a residual solvent amount of 1 to 20% by mass. a lateral stretching step in which the width direction is extended at a stretching ratio of 1.01 to 1.3 times, and a step of extending the casting film in the oblique direction with respect to the width direction, and the casting film is subjected to the following ( i) or (ii) heat treatment to obtain a heat treatment step of the first optical film, After the heat treatment step, the above-described bonding step is carried out to preferably produce the above polarizing plate.

(i) embossing the end portion of the cast film in the range of 180 to 220 ° C, and then winding it into a roll shape, under conditions of 60 to 80 ° C and 20% RH or less Heat treatment for 3 to 5 days.

(ii) The cast film is conveyed by a transfer roller at a tension of 120 to 150 N, and the cast film is heat-treated at 140 to 170 ° C for 40 to 600 seconds via the transfer roller.

Moreover, the liquid crystal display device of the present invention is characterized in that the polarizing plate is provided.

Further, an organic electroluminescence display device of the present invention is characterized by comprising the above polarizing plate.

Hereinafter, the present invention and its constituent elements and aspects and aspects of the present invention will be described in detail. In the present case, "~" is a meaning including the numerical values described before and after the lower limit value and the upper limit value.

Polarizer

The polarizing plate of the present invention includes a polarizing mirror, a first optical film that faces one of the polarizing mirrors, and a polarizing plate that faces the second optical film that is disposed to face the other of the polarizing mirrors.

As described later, the first optical film and the second optical film may be disposed on the side of the identification side of the optical film on the identification side, and may be provided with a functional layer such as a hardened layer or an anti-glare layer. Further, an adhesive layer may be provided between the polarizer and the first optical film, and between the polarizer and the second optical film. By.

The respective elements constituting the polarizing plate of the present invention will be described in detail below.

[1] Polarizer

A polarizer which is a main component of a polarizing plate is an element which passes only light of a polarizing surface in a certain direction, and a representative polarizer which is now known is a polyvinyl alcohol-based polarizing film. The polyvinyl alcohol-based polarizing film is one in which a polyvinyl alcohol-based film is subjected to iodine dyeing and a dichroic dye is dyed.

The polarizer may be formed by forming a film of a polyvinyl alcohol aqueous solution, and stretching it after uniaxial stretching, or performing uniaxial stretching after dyeing, and is preferably subjected to durability treatment with a boron compound. The film thickness of the polarizer is preferably from 1 to 30 μm, more preferably from 1 to 20 μm, still more preferably from 1 to 15 μm, even more preferably from 2 to 15 μm, from the viewpoint of film formation of the polarizing plate.

In addition, it is preferable to use the ethylene unit content of 1 to 4 mol%, the polymerization degree of 2000 to 4000, and the saponification degree of 99.0 to 99.99 as described in JP-A-2003-248123, JP-A-2003-342322, and the like. Ethylene-modified polyvinyl alcohol. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cut-off temperature of 66 to 73 ° C is preferably used. The polarizer using the ethylene-modified polyvinyl alcohol film is excellent in polarizing performance and durability, and is particularly suitable for a large liquid crystal display device because it has few color spots.

In addition, a coating type polarizer can be produced by the method described in JP-A-2011-100161, Japanese Patent No. 4691205, Japanese Patent No. 4751481, and Japanese Patent No. 4804589.

[2] First optical film

The first optical film of the present invention is disposed facing one of the polarizers. The first optical film is extended obliquely so that the angle θ between the slow axis and the absorption axis of the polarizer is in the range of 30 to 60°. Moreover, the dimensional change rate L(θ) in the slow axis direction of the first optical film and the dimensional change rate L (θ+90) in the direction orthogonal to the slow axis are adjusted so as to satisfy the following formulas (1) and (2).

Formula (1): 0.50 ≦ L (θ) / L (θ + 90) ≦ 0.95

Formula (2): 0.1 (%) ≦ L (θ) ≦ 1.5 (%).

The slow axis in the plane of the optical film-based film of the present invention is inclined with respect to the longitudinal direction (width direction), but particularly, the slow axis in the film plane is in the range of 30 to 60° with respect to the longitudinal direction (width direction), A circularly polarizing plate that converts linear polarization of a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light) is suitable for the optical film of the present invention.

In order to manufacture a practical circular polarizing plate, the optical film of the present invention is preferably a λ/4 plate. The λ/4 plate is designed to have a wavelength of a specific light (usually a visible light region), and the retardation value Ro in the plane of the layer is designed to be about 1/4. The λ/4 plate was measured at a wavelength of 590 nm and Ro (590) was in the range of 120 to 160 nm.

"Approximately 1/4 of the retardation in the wavelength range of visible light" means that the retardation value Ro expressed by the following formula (A) measured at a wavelength of 450 nm is longer at a wavelength of 400 to 700 nm. 450) and the retardation value Ro(590) measured at a wavelength of 590 nm, It is preferable to satisfy 1 < Ro (590) / Ro (450) ≦ 1.6. More preferably, it satisfies 1<Ro(590)/Ro(450)≦1.3. Further, in order to effectively function as a λ/4 plate, Ro (450) is preferably in the range of 60 to 125 nm, and the retardation value Ro (550) measured at a wavelength of 550 nm is preferably in the range of 75 to 150 nm. In the range of 125 to 142 nm, Ro(590) is in the range of 130 to 152 nm.

Formula (B) is an equation for determining the retardation value Rt in the film thickness direction. The retardation value Rt measured at a wavelength of 550 nm is preferably in the range of 60 to 100 nm, more preferably in the range of 70 to 90 nm.

Formula (A): Ro = (n _{x -} n _y ) × d

Formula (B): Rt={(n _x +n _y )/2-n _z }×d

Where nx, ny and n _z are 23 ° C. The refractive index nx of each of 55% RH, 450 nm, 550 nm, and 590 nm (the maximum refractive index in the plane of the film, also referred to as the refractive index in the slow axis direction), ny (in the plane of the film, the direction orthogonal to the slow axis) Refractive index), n _z (refractive index in the thickness direction of the film), and d is the thickness (nm) of the film.

Ro, Rt can be measured using an automatic birefringence meter. Automatic birefringence meter KOBRA-21AWR (manufactured by Oji Scientific Instruments Co., Ltd.) at 23 ° C. In a 55% RH environment, Ro is calculated by birefringence measurement at each wavelength.

When the angle between the slow axis of the λ/4 plate and the transmission axis (or absorption axis) of the polarizer is substantially 45°, a circular polarizing plate can be obtained. "Substantially 45°" means a range of 40 to 50 degrees. Slow in the λ/4 plate The angle between the axis and the transmission axis of the polarizer is preferably in the range of 41 to 49°, more preferably in the range of 42 to 48°, and more preferably in the range of 43 to 47°, and most preferably in the range of 44 to 46°. . Therefore, when the circularly polarizing plate is produced by the roll-to-roll method, the slow axis direction of the optical film of the present invention is preferably the above-mentioned "substantially 45°" direction.

The thickness of the first optical film of the present invention is preferably in the range of 15 to 50 μm, more preferably 20 to 40 μm, because the thickness of the thin film polarizing plate and the display device is increased. Within this range, an optical film having a light weight and a stable roll shape can be obtained.

The film length of the optical film of the present invention is preferably in the range of 1,500 to 8,000 m, more preferably in the range of 2,000 to 6,000 m in consideration of productivity.

[2-1] Characteristics of the first optical film

(surface roughness)

The arithmetic mean roughness Ra of the surface of the first optical film of the present invention is approximately in the range of 1.3 to 4.0 nm, preferably in the range of 1.6 to 3.5 nm.

(fault tolerance)

In the first optical film of the present invention, the failure (hereinafter also referred to as a defect) in the film is less preferable, and the "disadvantage" refers to the case where the film is formed by the solution casting method, which is caused by the rapid evaporation of the solvent during drying. Cavities in the film (foaming defects), or due to foreign matter in the film forming solution or film mixing Foreign matter in the film of foreign matter (foreign matter defect).

Specifically, in the film surface, the disadvantage of a diameter of 5 μm or more is preferably 1/10 cm square or less. More preferably, it is 0.5 /10 cm square or less, and particularly preferably 0.1 /10 cm square.

Further, the diameter of the above-mentioned disadvantage means a case where the diameter is a circle and the diameter thereof is not circular, and the maximum diameter (diameter of the circumscribed circle) is determined by the following method by microscopic observation of the range of the defect.

The range of disadvantages, when the disadvantage is bubbles or foreign matter, can be determined by using the differential interference microscope to observe the shadow size of the shortcomings observed by the transmitted light. Further, when the surface shape is changed such as transfer or scratching of the roller flaw, the difference is observed by the differential reflection of the reflected light of the microscope.

In the case of observation by reflected light, when the size of the defect is not clear, aluminum or platinum may be vapor-deposited on the surface for observation. When it is desired to obtain a film of excellent quality expressed by such a defect frequency with good productivity, an effective method is to filter the raw material solution of the optical film with high precision before casting, or to improve the cleanliness of the periphery of the casting machine, or to set the casting stepwise. After the drying conditions, the foaming is effectively suppressed to dry.

When the number of defects is more than one /10 cm square, for example, when a tension is applied to the film during processing in the subsequent step, the film may be broken and the productivity may be lowered. When the diameter of the defect is 5 μm or more, it may be visually confirmed by observing a polarizing plate or the like, and a bright spot may be generated when used as an optical member.

(breaking elongation)

Further, in the optical film of the present invention, the elongation at break in at least one direction (TD direction or MD direction) is preferably 4% or more, more preferably 10% or more, as measured according to JIS-K7127-1999.

The upper limit of the rupture elongation is not particularly limited, and the elongation at break tends to be lowered by elongation at a high elongation. As in the present invention, it is preferred to perform the oblique extension after the preliminary extension in the TD direction. It is preferably 30% or less, more preferably 20% or less.

(total light transmittance)

The optical film of the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, the upper limit of reality is about 99%. By introducing no additives or copolymerized components that absorb visible light, or removing foreign matter in the polymer by high-precision filtration, the light diffusion or absorption inside the film can be effectively reduced to achieve excellent transparency expressed by the total light transmittance. Sex. Moreover, the surface roughness of the film surface is reduced by reducing the surface roughness of the film contact portion (cooling roller, rolling roller, drum, conveyor belt, coating substrate during solution film formation, transfer roller, etc.) during film formation. Degree, can effectively reduce the light diffusion or reflection on the surface of the film.

[2-2] Dimensional change rate of the first optical film

The dimensional change rate of the first optical film of the present invention is measured by the following method.

[1] parallel to the TD direction or the MD direction, and The first optical film was taken in two squares of 10 cm, and was used for measurement of dimensional change in the slow axis direction and the direction orthogonal to the slow axis direction. When the dimensional change of the distance between two points was measured, the interval was 8 cm for the film, and the razor cross was cut at two points for the slow axis direction and the direction orthogonal to the slow axis direction at 23 ° C. Place in a 20% RH environment for 24 hours.

The humidity-modulated film is placed on a microscope table under the same 23 ° C, 20% RH environment, and then placed on a glass plate to be fixed, and used in the direction of the slow axis and the direction orthogonal to the slow axis direction. The microscope precisely measures the size (8 cm) between the two cross-cuts, L ₀ (θ) and L ₀ (θ+90).

The microscope was Nikon MEASURESCOPE MM-11 (eyepiece: ×10 objective lens: ×3) manufactured by Nikon, and the data measuring machine was directly connected to the microscope using Nikon DP-302 DATA PROCESSOR, and the obtained data was output to the table calculation software.

[2] The film was moved to 23 ° C. Under the environment of 80% RH, after 24 hours, at the same 23 ° C. In the 80% RH temperature and humidity environment, the size between the two cross-cuts is measured by the microscope and the data measuring machine in the direction of the slow axis and the direction orthogonal to the slow axis, respectively, L ₁ ( θ), L ₁ (θ+90).

[3] Substituting the respective sizes obtained in [1] and [2] into the following formulas (a) and (formula b), and determining the dimensional change ratio of the first optical film as L(θ) and L ( θ+90).

(Formula a): L(θ)(%)=(L ₁ (θ)-L ₀ (θ))/L ₀ (θ)×100

(Formula b): L(θ+90)(%)=(L ₁ (θ+90)-L ₀ (θ+90))/L ₀ (θ+90)×100

In the present invention, the dimensional change rates L(θ) and L(θ+90) of the first optical film thus obtained satisfy the above formulas (1) and (2). Thereby, the difference in dimensional change in the surface direction of the first optical film can be reduced, and the occurrence of physical deformation can be suppressed.

The means for adjusting the dimensional change ratio of the first optical film of the present invention to the range represented by the above formulas (1) and (2) is not particularly limited, and can be adjusted by the following means.

That is, the cast film obtained by casting the solution is stretched in the width direction, and in the width direction, after stretching in the oblique direction, the end portion of the cast film is applied in the range of 180 to 220 ° C. After the embossing, in a state of being wound into a roll, the temperature change rate can be adjusted by heating for 3 to 5 days under conditions of 60 to 80 ° C and 20% RH or less. Further, after extending in the oblique direction, the cast film is conveyed by a transfer roller at a tension of 120 to 150 N, and the cast film is heated at 140 to 170 ° C for 40 to 600 seconds via a transfer roller, and can be adjusted. Dimensional change rate.

Further, the first optical film preferably has a dimensional change ratio L (MD) in the longitudinal direction and a dimensional change ratio L (TD) in the width direction satisfying the following formula (3). Thereby, a polarizing plate in which the occurrence of a surface failure or a planar failure is suppressed can be formed.

Equation (3): 0.50 ≦ L (MD) / L (TD) < 1.00

The dimensional change rates L (MD) and L (TD) can be obtained by the same method as the above measurement method.

[2-3] Composition of the first optical film

The composition of the first optical film of the present invention may be any material known in the art, as long as the dimensional change rate of the first optical film satisfies the materials of the above formulas (1) and (2). A polymer of a skeleton (hereinafter also referred to as "cellulose derivative") is preferred. The content ratio of the cellulose derivative in the first optical film is preferably 55 mass% or more, preferably 70 mass% or more.

The cellulose derivative is a compound using cellulose as a raw material. Examples of the cellulose derivative include a cellulose ester (described later in detail), a cellulose ether (for example, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cyanoethyl cellulose). Etc.), cellulose ether ester (for example, etidylmethylcellulose, ethyl ethylethylcellulose, ethyl hydroxyethylcellulose, benzhydryl hydroxypropylcellulose, etc.), cellulose carbonate A resin such as an ester (for example, cellulose ethyl carbonate or the like) or a cellulose urethane (for example, a cellulose phenyl urethane) is preferably a cellulose ester. The cellulose derivative may be one type or a mixture of two or more types.

The cellulose ester is preferably one having a fluorenyl group in the range of 2 to 4 carbon atoms. Examples of the fluorenyl group having a carbon number of 2 to 4 include an ethyl group, a propyl group and a butyl group.

The glucose unit constituting the β-1,4 bond of cellulose has a free hydroxyl group at the 2, 3 and 6 positions. A cellulose ester is a polymer in which some or all of the hydroxyl groups are deuterated by a mercapto group (polymerization) ()). The total thiol group degree of substitution refers to the ratio of the total oxime of the cellulose in the 2nd, 3rd, and 6th positions of the hydroxy group (100% of the oxime to the degree of substitution 3).

Preferred examples of the fluorenyl group include, for example, an ethyl group, a propyl group, a butyl group, a butyl group, a hexyl group, a decyl group, a decyl group, a dodecyl group, a tridecyl fluorenyl group, and a tetradecane fluorene group. Base, hexadecane decyl, octadecyl fluorenyl, isobutyl fluorenyl, tert-butenyl, cyclohexanecarbenyl, anthracenyl, benzamyl, naphthylcarbonyl, cinnamyl, and the like. Among these, an ethyl group, a propyl group, a butyl group, a dodecyl group, an octadecyl group, a tert-butyl group, an oil group, a benzepidine group, a naphthylcarbonyl group, or a cinnamyl group are more preferred. Etc., especially, it is an ethyl group, a propyl group, and a butyl group (the fluorenyl group is a carbon number of 2 to 4).

Specific cellulose esters, preferably selected from the group consisting of cellulose (di, tri) acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyric acid At least one of ester, cellulose acetate phthalate, cellulose phthalate, and cellulose acetate benzoate.

Among these, more preferred cellulose esters are cellulose (di-, tri) acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate Acid ester.

The cellulose triacetate is preferably a cellulose acetate triacetate having an average degree of acetification (combined amount of acetic acid) of 54.0 to 62.5%, more preferably an average degree of vinegar of 58.0 to 62.5%.

Cellulose diacetate is preferably used with an average degree of acetification (knot The amount of acetic acid is 51.0~56.0%. Commercially available products include, for example, L20, L30, L40, and L50 manufactured by DAICEL, and Ca398-3, Ca398-6, Ca398-10, Ca398-30, and Ca394-60S manufactured by Eastman Chemical Japan Co., Ltd.

Cellulose acetate propionate or cellulose acetate butyrate has a fluorenyl group having 2 to 4 carbon atoms as a substituent. When the degree of substitution of ethyl ketone group is X, the degree of substitution of propyl fluorenyl or butyl fluorenyl group is In the case of Y, it is preferred to satisfy the following formulas (I) and (II) at the same time.

Formula (I): 2.0≦X+Y≦2.95

Formula (II): 0≦X≦2.5

Among them, it is preferably 1.9 ≦ X ≦ 2.5, 0.1 ≦ Y ≦ 0.9.

The measurement method of the degree of substitution of the above thiol groups can be measured in accordance with ASTM-D817-96.

The weight average molecular weight Mw of the cellulose ester is preferably in the range of 80,000 to 300,000, more preferably in the range of 120,000 to 250,000, from the viewpoint of controlling the elastic modulus. When it is in the above range, it is easy to control the stability of the winding shape of the film or the bleed resistance of the additive by the elastic modulus of elongation at the time of film formation.

The number average molecular weight (Mn) of the cellulose ester is in the range of 30,000 to 150,000, and the optical film obtained is preferably high in mechanical strength. In addition, a cellulose ester having an average molecular weight of from 40,000 to 100,000 is more suitable for use.

Weight average molecular weight (Mw) and number average of cellulose ester The ratio of the molecular weight (Mn) ratio (Mw/Mn) is preferably in the range of 1.4 to 3.0.

The weight average molecular weight Mw and the number average molecular weight Mn of the cellulose ester were measured using gel permeation chromatography (GPC).

The measurement conditions are as follows.

Solvent: dichloromethane

Pipe column: Shodex K806, K805, K803G (Showa Electric (share) system 3 connections)

Column temperature: 25 ° C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (made by GL SCIENCES)

Pump: L6000 (Hitachi Manufacturing Co., Ltd.)

Flow rate: 1.0ml/min

Calibration curve: A calibration curve obtained using a sample of 13 samples of standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 1000000 to 500. 13 samples were used at approximately equal intervals.

The raw material cellulose of the cellulose ester used in the present invention may be a wood pulp or cotton linter, and the wood pulp may be a conifer or a broad-leaved tree, but a conifer is preferred. From the viewpoint of the peeling property at the time of film formation, it is preferable to use cotton wool. The cellulose esters produced by these may be suitably mixed or may be used singly.

For example, cellulose esters from cotton linter: cellulose esters from wood pulp (coniferous trees): from wood pulp (broadleaf trees) The ratio of cellulose ester can be 100:0:0, 90:10:0, 85:15:0, 50:50:0, 20:80:0, 10:90:0, 0:100:0, 0: 0:100, 80:10:10, 85:0:15, 40:30:30.

The cellulose ester of the present invention can be produced by a known method. In general, the cellulose of the raw material, a specific organic acid (acetic acid, propionic acid, etc.), an acid anhydride (acetic anhydride, propionic anhydride, etc.), and a catalyst (such as sulfuric acid) are mixed, and the cellulose is esterified to carry out a reaction until it is formed. Until the cellulose triester. The triester is the three hydroxyl groups of the glucose unit and is substituted with an organic acid acrylic acid. Meanwhile, when two kinds of organic acids are used, a cellulose ester of a mixed ester type such as cellulose acetate propionate or cellulose acetate butyrate can be produced. Next, a cellulose ester having a desired degree of substitution of a thiol group is synthesized by hydrolyzing a cellulose triester. Then, the steps of filtration, precipitation, water washing, dehydration, drying, and the like are carried out to obtain a cellulose ester.

1 g of the cellulose ester of the present invention is placed in 20 ml of pure water (electrical conductivity: 0.1 μS/cm or less, pH 6.8), and the pH at the time of stirring at 25 ° C for 1 hr in a nitrogen atmosphere is in the range of 6 to 7. The conductivity is preferably in the range of 1 to 100 μS/cm.

The cellulose ester of the present invention can be specifically synthesized by referring to the method described in JP-A-10-45804.

[2-4] Additives

The first optical film may contain an additive. Examples of the additive include a plasticizer, an ultraviolet absorber, a retardation adjuster, an antioxidant, a deterioration preventive agent, a release aid, a surfactant, a dye, a fine particle, and the like. This embodiment In the state, the additive other than the fine particles may be added during the preparation of the solution of the cellulose ether or the like, or may be added during the preparation of the fine particle dispersion. A polarizing plate used for an image display device such as an organic EL display is preferably a plasticizer, an antioxidant, an ultraviolet absorber or the like which is added with heat and moisture resistance.

These additives are added in an amount of, for example, 1 to 30% by mass, preferably 1 to 20% by mass, based on the cellulose ester. Further, in order to suppress bleeding during stretching and drying, it is preferred that the vapor pressure at 200 ° C is 1400 Pa or less.

(delay adjuster)

In order to adjust the compound to be added to the retardation, an aromatic compound having two or more aromatic rings as described in the specification of European Patent No. 911656A2 can be used.

Further, two or more kinds of aromatic compounds may be used in combination. The aromatic ring of the aromatic compound contains an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. Particularly preferred is an aromatic heterocyclic ring, and the aromatic heterocyclic ring is generally an unsaturated heterocyclic ring. Among them, a 1,3,5-triazine ring is particularly preferred.

(polymer or oligomer)

The first optical film contains a cellulose ester and a polymer or oligo of a vinyl compound having a substituent selected from a carboxyl group, a hydroxyl group, an amine group, a guanamine group, and a sulfo group, and having a weight average molecular weight of 500 to 200,000. The polymer is preferred. The quality of the cellulose ester and the content of the polymer or oligomer Preferably, it is in the range of 95:5 to 50:50.

(matting agent)

In the first optical film, fine particles as a matting agent can be added, whereby when the first optical film is elongated, it can be easily conveyed or wound.

The particle size of the matting agent is preferably a primary particle or a secondary particle of 10 nm to 0.1 μm. It is preferred to use a slightly spherical matting agent having a needle-to-particle ratio of 1.1 or less.

The fine particles are preferably those containing bismuth, and particularly preferably cerium oxide. The fine particles of ceria which are preferred in the present embodiment include, for example, AEROSILR 972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 manufactured by AEROSIL Co., Ltd. (the above is Japan AEROSI). The market name of the product is preferably AEROSIL 200V, R972, R972V, R974, R202, R812. Examples of the fine particles of the polymer include a silicone resin, a fluororesin, and an acrylic resin. Preferably, the epoxy resin is particularly preferably a three-dimensional network structure, and examples thereof include Tospear 1103, 105, 108, 120, 145, 3120, and 240 (Toshiba Silicon). .

(other additives)

Other heat stabilizers such as inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, and aluminum oxide, and salts of alkaline earth metals such as calcium and magnesium may be added. Further, a surfactant, a peeling accelerator, an antistatic agent, a flame retardant, a slip agent, an oil agent, or the like may be added.

[2-5] Method for producing first optical film

The method for producing the first optical film is not particularly limited, and for example, a solution casting film forming method or a melt casting film forming method can be used.

Moreover, the manufacturing method demonstrated below uses the cellulose ester which is the material of a 1st optical film.

[2-5-1] Method for casting film by solution casting

The case where the first optical film is produced by the solution casting film forming method can be produced by the following procedure. (1) a step of casting a cast film in which a material such as a cellulose ester and an additive is dissolved in a solvent is cast onto a support to form a cast film, and (2) a residual solvent amount is 1 to 20% by mass. a casting film having a lateral stretching step of extending at a stretching ratio of 1.01 to 1.3 times in the width direction, (3) an oblique stretching step of extending the casting film in the oblique direction with respect to the width direction, and (4) flow for the flow The film is stretched, and the heat treatment process of the first optical film is obtained by performing heat treatment of (i) or (ii) described later.

[2-5-1-1] casting step

In the dissolution pot, the cellulose ester and the additive are dissolved in a solvent to prepare a dope.

The solvent contained in the dope may be one type or a combination of two or more types. From the viewpoint of improving the production efficiency, it is preferred to use a good solvent for combining cellulose esters with a poor solvent. Good solvent means cellulose alone The ester is a good solvent, and the poor solvent means that the cellulose ester is swollen, or the single state is not dissolved. Therefore, good solvents and poor solvents vary depending on the average thiol substitution degree of the cellulose ester.

Examples of the good solvent include organic halogen compounds such as dichloromethane, dioxapentanes, acetone, methyl acetate and methyl acetoacetate, preferably dichloromethane.

Examples of the poor solvent include methanol, ethanol, n-butanol, cyclohexane, and cyclohexanone. In order to suppress the bleeding of the additive in the optical film constituting the roll body, methanol or ethanol is preferred.

The poor solvent may be one type or a mixture of two or more types. In the case where the lean solvent is a mixture of two or more kinds of poor solvents, the content of the poor solvent having a larger absolute value than the SP value (solubility parameter) of the additive is preferably the most.

In the case where a good solvent and a poor solvent are used in combination, in order to improve the solubility of the cellulose ester, it is preferred that the good solvent is more than the poor solvent. The mixing ratio of the good solvent to the poor solvent is preferably in the range of 70 to 98% by mass, and preferably in the range of 2 to 30% by mass.

The concentration of the cellulose ester in the dope is preferably higher in order to reduce the drying load, but when the concentration of the cellulose ester is too high, filtration is not easy. Therefore, the concentration of the cellulose ester in the dope is preferably in the range of 10 to 35 mass%, more preferably 15 to 25 mass%.

The method of dissolving a cellulose ester in a solvent can be, for example, a method of dissolving under heating and pressure, a method of adding a poor solvent to a cellulose ester to swell, adding a good solvent to dissolve, and a method of cooling and dissolving.

Among them, it is possible to heat to a boiling point of a normal pressure or higher, and therefore it is preferably a method of dissolving under heating and pressure. Specifically, when it is heated to a temperature equal to or higher than the boiling point of the normal pressure and stirred at a temperature within a range in which the solvent does not boil under pressure, generation of a lumpy undissolved substance called a gel or agglomerate can be suppressed.

The heating temperature is preferably from a viewpoint of solubility of the cellulose ester, but when the heating temperature is too high, the pressure required is increased, and the productivity is lowered. Therefore, the heating temperature is preferably in the range of 45 to 120 ° C, more preferably in the range of 60 to 110 ° C, and still more preferably in the range of 70 ° C to 105 ° C.

The obtained dope may contain, for example, an insoluble matter such as impurities contained in the cellulose ester of the raw material. This insoluble matter may become a bright foreign matter in the obtained film. In order to remove such insoluble matter or the like, it is preferred to re-filter the obtained dope.

Next, the prepared glue is passed through a press die to cast a metal support without a terminal (for example, a stainless steel belt or a rotating metal drum, etc.).

The shape of the slit of the metal mouth portion of the mold can be adjusted, and the press mold which makes the film thickness uniform can be easily adjusted. Examples of the pressurizing mold include a coat hanger die, a T die, and the like. The surface of the metal support is preferably mirror-finished.

The casting system modulates a plurality of dopes, and the above-mentioned plurality of dopes are cast onto a smoothing plate or a drum as a support, and a film can also be formed.

In this case, two or more kinds of glue can be simultaneously cast to the support. On the support, or separately to the support. In the case of the successive casting method of casting, the dope on the side of the support may be cast first, and after being dried to some extent on the support, the casting is superposed thereon. Further, in the case where three or more kinds of dopes are used, a simultaneous lamination (also referred to as co-casting) and successive casting may be suitably carried out to carry out casting, and a film having a laminated structure may be produced. The method of forming a film by co-casting or successive casting is different from the method of applying to a film after drying, and the interface of each layer having a laminated structure becomes unclear, and observation of a section is sometimes observed. The characteristics of the laminated structure are not clearly known, and the effect of improving the adhesion between the layers is obtained.

The co-casting can use a well-known co-casting method. For example, a plurality of casting openings provided at intervals by the traveling direction of the metal supporting body may be used to cast a solution containing deuterated cellulose, and a film may be formed by laminating, or, for example, Japanese Patent Laid-Open No. 61-158414, The method described in each of the publications of Japanese Laid-Open Patent Publication No. Hei No. Hei. Further, it is also possible to carry out thin film formation by casting a deuterated cellulose solution from two casting openings, for example, Japanese Patent Publication No. 60-27562, Japanese Patent Laid-Open No. 61-94724, and Japanese Patent Laid-Open No. 61- The method described in each of the publications of Japanese Patent Application Laid-Open No. Hei. No. Hei. No. Hei.

Next, the glue film is heated on the metal support, and the solvent is evaporated to obtain a web (WEB) (cast film).

The drying of the dope film is preferably carried out in an atmosphere in the range of 40 to 100 °C. When the glue film is dried in an atmosphere in the range of 40 to 100 ° C, hot air in the range of 40 to 100 ° C is contacted on the web, or borrowed Heating by infrared rays or the like is preferred.

The method for evaporating the solvent, for example, a method of blowing the surface of the slurry film, a method of transferring heat from the liquid on the back side of the conveyor belt, a method of transferring heat from the surface by radiant heat, etc., but by a liquid on the back side of the conveyor belt The heat transfer method is preferred because it has high drying efficiency.

Next, the obtained web was peeled off at the peeling position on the metal support. The temperature at the peeling position on the metal support is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C.

From the viewpoint of improving the surface quality, moisture permeability, and peelability of the obtained web, it is preferable to peel the web from the metal support within 30 to 120 seconds after casting.

The amount of residual solvent of the web at the time of peeling at the peeling position on the metal support varies depending on the drying conditions, the length of the metal support, and the like, but is preferably in the range of 50 to 120% by mass. The web having a large amount of residual solvent is too soft, and the flatness is easily damaged, and wrinkles or lines are easily generated in the casting direction (MD direction) of the peeling tension. In order to suppress wrinkles or lines in the casting direction (MD direction), the amount of residual solvent of the web at the peeling position can be set.

The amount of residual solvent in the web is defined by the following formula.

Residual solvent amount (% by mass) = {(M - N) / N} × 100

Further, the mass of the sample taken at the time before the extension of the M-based web or the film, and the mass of the N-based M at 115 ° C for 1 hour.

Peeling tension when the web is peeled off by the metal support, usually It can be 300 N/m or less.

The web obtained by peeling off the metal support is dried. The web is dried, and the web can be conveyed while being conveyed to the web by a plurality of rollers arranged on the upper and lower sides, or the both ends of the web may be fixed by a cooker while being conveyed and dried.

The drying method of the web can be carried out by hot air, infrared rays, heating rollers, microwaves, etc., and it is preferable to use a method of drying by hot air. The drying temperature of the web may be about 40 to 250 ° C, preferably about 40 to 160 ° C.

[2-5-1-2] Horizontal extension step

Next, a web in a state in which the amount of the residual solvent is from 1 to 20% by mass is a lateral stretching step in which the stretching is performed in the width direction (TD direction) in the range of the stretching ratio of 1.01 to 1.3 times. The lateral stretching step is preferably carried out continuously after the above-described casting step, without winding the obtained web.

By extending the web, an optical film having the desired retardation can be obtained. The retardation of the optical film can be controlled by adjusting the amount of tension applied to the web.

The stretching ratio of the web is preferably in the range of 1.01 to 1.3 times, more preferably in the range of 1.07 to 1.15 times.

The extension temperature of the web is preferably in the range of 120 to 200 ° C, more preferably in the range of 135 to 170 ° C.

The method for extending the web is not particularly limited, and it is preferred to fix the ends of the web with a cookware or a needle, and extend the spacing of the cookware or the needle to extend the web. Extend the tenter extension method, etc.

The amount of the residual solvent in the web at the time of the lateral stretching step is preferably in the range of 1 to 20% by mass, more preferably in the range of 3 to 20% by mass, still more preferably in the range of 3 to 10% by mass.

[2-5-1-3] oblique extension step

Next, a laterally extending film (cast film) obtained by extending in the width direction is subjected to an oblique stretching step of extending in the oblique direction with respect to the film width direction.

When the transversely extending film which is extended in the width direction is further extended obliquely, it is preferable to use a device which can be obliquely extended. Describe the device that can be tilted and extended.

(summary of the device)

Fig. 1 is a schematic plan view showing an example of a schematic configuration of a manufacturing apparatus 1 which can be obliquely extended. The manufacturing apparatus 1 is provided with the film feeding part 2, the conveyance direction changing part 3, the guide roll 4, the extension part 5, the guide roll 6, and the conveyance direction change part 7 in the upstream of the conveyance direction of the elongate film. The film cutting device 8 and the film winding portion 9. Further, the details of the extension portion 5 will be described later. Further, after the oblique stretching step, the next step can be carried out without winding the obliquely stretched film. In this case, the manufacturing apparatus 1 does not have to include the film winding portion 9. Further, when it is not necessary to cut the elongated film, the manufacturing apparatus 1 does not have to include the film cutting device 8.

The film feed-out section 2 is the above width The elongated transversely stretched film (cast film) in which the direction is extended is sent out and supplied to the extending portion 5. The film delivery portion 2 may be configured separately from the film forming device of the web, or may be integrally formed. In the former case, after the film is formed, the film is wound around the winding core to form a wound body (long film material), and the film is fed out from the film feeding portion 2. On the other hand, in the latter case, after the film forming portion 2 is formed into a web, the web is not wound and the lateral stretching step is performed, and the film is fed out to the extending portion 5.

The conveyance direction changing unit 3 changes the conveyance direction of the film fed by the film feed unit 2 to the direction of the entrance of the extension portion 5 which is an obliquely extending tenter. The conveyance direction changing unit 3 may include, for example, a rotating bar that transfers the film while changing the conveying direction, or a rotating table that rotates the rotating bar in a plane parallel to the film.

By changing the conveyance direction of the film in the conveyance direction changing unit 3 as described above, the width of the entire manufacturing apparatus 1 can be narrowed, and the film can be finely controlled to be conveyed and angled, and the film thickness and the optical value can be obtained. Small elongated obliquely extending film. Further, when the film feeding portion 2 and the conveying direction changing portion 3 are movable (slidable and rotatable), it is possible to effectively prevent the left and right cookware (holding) of the extending portion 5 at both end portions in the width direction of the elongated film. Having a poor occlusion of the film.

Further, the film feeding portion 2 slidably and rotatably feeds the elongated film at a specific angle to the entrance of the extending portion 5. In this case, the configuration in which the transport direction changing unit 3 is omitted may be omitted.

The guide roller 4 is provided at least one upstream side of the extending portion 5 in order to stabilize the rail when the film is moved. Also, the guide roller 4 can be a crucible The pair of roller pairs on the upper and lower sides of the film may be formed by a plurality of roller pairs. The guide roller 4 closest to the entrance of the extending portion 5 is a passive roller that guides the movement of the film, and is rotatably supported by the shaft via a bearing portion (not shown). The material of the guide roller 4 can be used by a known person. In order to prevent the film from being damaged, it is preferable to reduce the weight of the guide roller 4 by applying ceramic coating on the surface of the guide roller 4 or by chrome plating a light metal such as aluminum.

Further, it is preferable that one of the rolls on the upstream side of the guide rolls 4 closest to the entrance of the extending portion 5 is preferably a pinch rubber roll. By making such a nip roll, variation in the delivery tension of the film in the moving direction can be suppressed.

A pair of bearing portions of both ends (left and right) of the guide roller 4 closest to the entrance of the extending portion 5 may be provided with a first tension detecting device as a film tension detecting device for detecting the tension generated by the film in the roller The second tension detecting device. The film tension detecting device can use, for example, a load cell. The force detector can be used by a known type of stretch or compression type. The load cell is converted into an electrical signal for detection by a strain gauge attached to a strain body (STRAIN BODY) with a load applied to the force point.

The force measuring device independently detects the force of the moving film on the roller by the left and right bearing portions of the guide roller 4 disposed at the entrance closest to the extending portion 5, that is, the vicinity of the two sides of the film. The tension in the direction in which the film travels. Further, the strain gauge is directly attached to the support body constituting the bearing portion of the roller, and the load, that is, the film tension, can be detected based on the strain (Strain) generated by the support. The relationship between strain and film tension is pre- The first measurement is known.

The position and the conveyance direction of the film supplied to the extending portion 5 by the film feeding portion 2 or the conveying direction changing portion 3 are deviated from the position toward the inlet of the extending portion 5 and the conveying direction, and the deviation amount is the closest to the extending portion 5. The tension between the sides of the film of the guide roller 4 of the inlet is different. Therefore, by providing the film tension detecting device as described above, the degree of the deviation can be determined by detecting the above-described tension difference. In other words, when the transport position and the transport direction of the film are the same (when the position and direction of the entrance of the extension portion 5), the load acting on the guide roller 4 is substantially equal at both ends in the axial direction, but if it is not at the time, it is left and right. The film tension is different.

Therefore, in order to make the difference in film tension between the left and right sides of the guide roller 4 closest to the entrance of the extending portion 5 equal, for example, the position of the film and the conveying direction (the angle to the entrance of the extending portion 5) are appropriately adjusted by the conveying direction changing unit 3 When the film is held by the holder of the entrance portion of the extending portion 5, the obstacle such as the deviation of the gripper can be reduced. Further, the physical properties in the width direction of the film extended by the inclination of the extending portion 5 can be stabilized.

The guide roller 6 is provided with at least one downstream side of the extending portion 5 in order to stabilize the rail when the extending portion 5 is moved by the obliquely extending film.

The conveyance direction changing unit 7 changes the conveyance direction of the film which has been extended by the extension unit 5 to the direction toward the film winding unit 9.

Here, in order to correspond to the fine adjustment or the product change of the alignment angle (the direction of the slow axis in the plane of the film), it is necessary to adjust the entrance at the extension 5 The angle between the direction in which the film travels and the direction of travel of the film at the exit of the extension 5 is. In order to adjust this angle, it is necessary to change the traveling direction of the film after film formation by the conveyance direction changing unit 3, to guide the film to the entrance of the extension portion 5, and/or to change the extension portion 5 by the conveyance direction changing unit 7. The traveling direction of the film sent out at the outlet returns the film to the direction of the film winding portion 9.

Further, film formation and oblique stretching are continuously performed, and it is preferable from the viewpoint of productivity or yield. When the film forming step, the tilting step, and the heat treatment step are continuously performed, the traveling direction changing unit 3 and/or the conveying direction changing unit 7 change the traveling direction of the film, and the film forming step and the heat processing step are performed to advance the film. The direction is the same, that is, as shown in FIG. 1, the traveling direction (feeding direction) of the film fed by the film feeding portion 2 and the traveling direction of the film before being wound by the film winding portion 9 (winding) The direction is the same, and the width of the device for the direction in which the film travels can be reduced.

Further, although it is not always necessary to make the traveling direction of the film uniform in the film forming step and the heat treatment step, the transport direction is changed in order to prevent the film feed portion 2 and the film winding portion 9 from interfering with each other. The portion 3 and/or the conveyance direction changing unit 7 preferably change the traveling direction of the film.

The above-described conveyance direction changing sections 3 and 7 can be realized by a known method using an air blowing roller or an air rotating rod.

In the film cutting device 8, the film (the elongated obliquely extending film) in which the extending portion 5 is extended is cut along the cross section including the width direction, and has a cutting member. The cutting member is, for example, a scissors or a cutting knife (including A slitter or a band knife (Thomson knife) is used. However, the present invention is not limited thereto, and other circular saws or laser irradiation devices that can be rotated can be used.

The film winding portion 9 is wound around a film conveyed by the extending portion 5 via the conveying direction changing portion 7, and is constituted by, for example, a winder device, an accumulator, a driving device, or the like. The film winding portion 9 is preferably configured to be slidable in the lateral direction in order to adjust the winding position of the film.

The film winding portion 9 pulls the film at a specific angle with respect to the exit of the extending portion 5, and can finely control the pulling position and angle of the film. Thereby, an elongated obliquely stretched film having a small thickness and a small variation in optical value can be obtained. Further, it is possible to effectively prevent the occurrence of wrinkles in the film, and to wind the film in an elongated shape in order to add the winding property of the film.

The film winding portion 9 constitutes a pulling portion that pulls the conveyed film extending in the extending portion 5 at a constant tension. Further, a pulling roller for pulling the film at a constant tension may be provided between the extending portion 5 and the film winding portion 9. Further, the above-described guide roller 6 can also have the function as the above-described traction roller.

In the present embodiment, the drawing tension (N/m) of the stretched film is between 100 N/m < T < 300 N/m, preferably 150 N/m < T < 250 N/m. Adjustment. When the above-mentioned pulling tension is 100 N/m or less, slack or wrinkles of the film are likely to occur, and the film in the width direction of the retardation and the alignment angle is deteriorated. On the other hand, when the pulling tension is 300 N/m or more, the deviation in the width direction of the film of the alignment angle is deteriorated. The wide yield (efficiency in the width direction) is deteriorated.

Further, in the present embodiment, the variation of the traction tension T is controlled to less than ±5%, and it is preferable to control the accuracy to less than ±3%. When the variation of the traction tension T is ±5% or more, the variation in the optical characteristics in the width direction and the moving direction (transport direction) becomes large. The method of controlling the fluctuation of the traction tension T within the above range includes, for example, measuring the load of the first roller (guide roller 6) applied to the outlet side of the extending portion 5, that is, the tension of the film, and fixing the value. A method of controlling the rotational speed of the winding roller of the pulling roller or the film winding portion 9 by a general PID control method. The method of measuring the above load may be, for example, a method of attaching a load cell to a bearing portion of the guide roller 6, and measuring the load applied to the guide roller 6, that is, the tension of the film. The force measuring device can utilize a known type of stretch type or compression type.

The extended film is released by the grip of the extension 5, and is discharged from the outlet of the extension 5 to hold both ends (both sides) of the film held by the holder, if necessary, after trimming. The film cutting device 8 is cut into a specific length, and is wound around a winding core (winding roll) in order to form a wound body of the obliquely stretched film.

(details of extension)

Next, the details of the above-described extension portion 5 will be described. 2 is a schematic plan view showing an example of a track pattern of the extension portion 5. However, this is an example, and the configuration of the extension portion 5 is not limited thereto.

In the obliquely extending step in the present embodiment, the extending portion 5 is preferably formed using a tenter (inclined stretching machine) which is tiltably extendable. this The tenter is a device that heats the elongated film to any temperature that can be extended and performs oblique stretching. The tenter has a heating zone Z, one pair of left and right tracks Ri. Ro, and the track Ri. Ro walking and transporting most of the holdings of the film Ci. Co (in Figure 2, only one set of grippers). Further, the details of the heating zone Z will be described later. Track Ri. Each of Ro is connected to a plurality of rail portions by a connecting portion (the white circle in Fig. 2 is an example of a connecting portion). Holding a Ci. Co is composed of a cooker that grips both ends of the film in the width direction.

In Fig. 2, the feeding direction D1 of the elongated film is different from the winding direction D2 of the elongated elongated extending film, and a feeding angle θ i is formed between the winding direction D2. When the delivery angle θ i exceeds 0° and is less than 90°, the desired angle can be intentionally set.

Thus, since the feeding direction D1 is different from the winding direction D2, the track pattern of the tenter is asymmetrical left and right. Further, it is possible to adjust the track pattern manually or automatically by providing the alignment angle θ, the stretching ratio, and the like of the manufactured elongated obliquely extending film. The tilting stretcher used in the manufacturing method of the present embodiment is freely set to constitute the track Ri. It is preferable that the position of each track portion and the track connecting portion of Ro can be arbitrarily changed.

In this embodiment, the holder of the tenter is Ci. Co and the front and rear holdings Ci. Co keeps a certain interval and walks at a certain speed. Holding a Ci. The walking speed of Co can be suitably selected, and is usually 1 to 150 m/min. A pair of left and right grips Ci. The difference in the traveling speed of Co is usually 1% or less, preferably 0.5% or less, and more preferably 0.1% or less. This is because at the exit of the extension step, when there is a speed difference between the left and right sides of the film, wrinkling occurs at the exit of the extension step, so the left and right Holding a Ci. The speed difference of Co essentially requires the same speed. In the case of a general tenter device or the like, the speed of the motor is driven in accordance with the cycle of the hinge teeth of the drive chain, and the speed of the motor is not uniform at a level of seconds or less, and sometimes unevenness of several % is generated, but the implementation of the present invention is not performed. The speed difference described in the form.

In the tilting stretcher used in the manufacturing method of the present embodiment, in particular, the film is conveyed at an inclined position, and the track of the track of the gripper is defined, and a large bending rate is sometimes required. In order to avoid the interference of the grippers or the local stress concentration caused by the rapid bending, it is preferable to make the trajectory of the gripper into a curved line in the curved portion.

In this way, the obliquely extending tenter for imparting the alignment in the oblique direction to the elongated film can be freely set to the alignment angle of the film by changing the pattern of the track, and the alignment axis (slow axis) of the film can be made horizontal. It is preferable to have a high-precision alignment across the width direction of the film, and to accurately control the thickness of the film or the retarder.

Next, the extension operation of the extension portion 5 will be described. The ends of the long film are held by the left and right grips Ci. Co control, in the heating zone Z with the gripper Ci. Co walked and was transported. Left and right grips Ci. Co is in the entrance portion of the extension portion 5 (the position in the figure A), and the direction perpendicular to the direction of the film (the direction of delivery D1) is relatively perpendicular, so that the left and right asymmetrical tracks Ri. Each of the Ros walks, and at the exit portion (the position of B in the figure) at the end of the extension, the held film is released. After holding the Ci. The Co-released film is wound around the winding core by the film winding portion 9. A pair of tracks Ri. Ro, each has an endless continuous track, at the exit of the tenter, release the holding grip of the film Ci. Co, walking the outer track, Return to the entrance in sequence.

At this time, the track Ri. Ro is asymmetrical to the left and right, so in the example of Fig. 2, the position of A in the figure is opposite to the left and right holdings Ci. Co, along with the walking track Ri. In Ro, the gripper Ci of the traveling rail Ri side (inner path side) has a positional relationship with respect to the gripper Co of the traveling rail Ro side (outer path side).

That is, in the position of A in the figure, for the film sending direction D1, the direction of the vertical direction is opposite to the holding tool Ci. Among the Cos, one of the holding grips Ci first reaches the position B at the end of the extension of the film, and the connecting gripper Ci. The straight line of Co is inclined at an angle θ L with respect to a direction slightly perpendicular to the winding direction D2 of the film. Therefore, the elongated film extends obliquely at an angle of θ L with respect to the width direction. Here, the slightly vertical line indicates a range of 90 ± 1°.

Next, the details of the above-described heating zone Z will be described. The heating zone Z of the extension 5 is composed of a preheating zone Z1, an extension zone Z2 and a heat fixing zone Z3. In the extension 5, by holding the holder Ci. The film held by Co passes through the preheating zone Z1, the extension zone Z2, and the heat fixing zone Z3. In this embodiment, the preheating zone Z1 and the extension zone Z2 are separated by a partition wall, and the extension zone Z2 and the heat fixing zone Z3 are separated by a partition wall.

The preheating zone Z1 refers to the holding part Ci of the two ends of the film in the inlet portion of the heating zone Z. Co, the left and right (film width direction) keeps the interval of walking at a certain interval.

The extension zone Z2 refers to the gripper Ci holding the two ends of the film. The interval of Co is turned on until it becomes a section of a specific interval. this In the case of the above-described oblique extension, if necessary, it is also possible to extend in the longitudinal direction or the lateral direction before and after the oblique extension.

The hot fixed zone Z3 refers to the gripper Ci after the extension zone Z2. The interval between Co becomes a certain interval again, and the grips at both ends are Ci. Co keeps the interval of walking parallel to each other.

Further, after the stretched film passes through the heat-fixing zone Z3, the temperature in the zone may be set to a zone (cooling zone) equal to or lower than the glass transition temperature Tg (°C) of the thermoplastic resin constituting the film. At this time, when considering the shrinkage of the film due to cooling, it is also possible to hold the opposing holder Ci in advance. Co-spaced reduced orbital pattern.

The temperature of the preheating zone Z1 is set to Tg~Tg+30°C, the temperature of the extension zone Z2 is set to Tg~Tg+30°C, the temperature of the heat fixing zone Z3 and the temperature of the cooling zone, relative to the glass transition temperature Tg of the thermoplastic resin. It is preferably set to Tg-30~Tg+20°C.

Moreover, the lengths of the preheating zone Z1, the extension zone Z2, and the heat fixing zone Z3 may be appropriately selected. The length of the preheating zone Z1 is usually 100 to 150% with respect to the length of the extension zone Z2, and the length of the heat fixing zone Z3 is usually 50~100%.

Further, when the width of the film before stretching is Wo (mm), and the width of the film after stretching is W (mm), the stretching ratio R (W/Wo) in the oblique stretching step is preferably 1.3 to 3.0, more preferably It is 1.5~2.8. When the stretching ratio is in this range, the thickness unevenness in the width direction of the film becomes small, which is preferable. In the extension zone Z2 of the obliquely extending tenter, when the extension temperature difference is set in the width direction, the thickness unevenness in the width direction can be made better. (LEVEL). Further, the above-described stretching magnification R is equal to the interval W1 between the both ends of the gripper held at the tenter inlet portion, and the magnification (W2/W1) at the interval of the gap W2 at the tenter exit portion.

Further, the method of extending the slanting portion of the extending portion 5 is not limited to the above-described method, and the slanting extension may be performed by simultaneous biaxial stretching as disclosed in Japanese Laid-Open Patent Publication No. 2008-23775. At the same time, the biaxial stretching means that both end portions in the width direction of the supplied elongated film are held by the respective grippers, and the elongated film is conveyed while moving the respective holders, and the conveying direction of the elongated film is fixed. The method of extending the elongated film in the oblique direction with respect to the width direction by changing the moving speed of one of the grippers to the moving speed of the other gripper. Others may be obliquely extended by the technique disclosed in Japanese Laid-Open Patent Publication No. 2011-11434.

The elongated obliquely extending film obtained by the above oblique stretching step has an alignment angle θ with respect to the winding direction, for example, a range of more than 0° and less than 90°, and a width of at least 1300 mm, an in-plane retardation in the width direction. The deviation of Ro is 10 nm or less, and the deviation of the alignment angle θ is preferably 10 or less. Further, the in-plane retardation value Ro (550) measured at a wavelength of 550 nm of the elongated obliquely stretched film is preferably in the range of 60 to 220 nm, more preferably in the range of 65 to 200 nm, still more preferably 75 to 150 nm. Within the scope.

In other words, in the elongated obliquely stretched film obtained by the production method of the present embodiment, the variation in the in-plane retardation Ro is 2 nm or less, preferably 1 nm or less, in at least 1300 mm in the width direction. An example of an elongated obliquely extending film by making the deviation of the in-plane retardation Ro within the above range When used as a retardation film for a liquid crystal display device, it is also possible to form a display quality.

Further, in the elongated obliquely stretched film obtained by the production method of the present embodiment, the deviation of the alignment angle θ is preferably 10 or less, more preferably 5 or less, and most preferably 1 in at least 1300 mm in the width direction. ° below. When the long obliquely extending film having a deviation of the alignment angle θ of more than 0.5 is bonded to the polarizing mirror as a circular polarizing plate, when it is mounted on an image display device such as an organic EL display device, light leakage may occur and the contrast between light and dark may be lowered. situation.

The retardation value Ro is the difference between the refractive index nx in the in-plane slow axis direction and the refractive index ny in the direction orthogonal to the slow axis in the plane, multiplied by the value of the average thickness d of the film (Ro=(nx-ny) ×d).

The average thickness of the elongated obliquely stretched film obtained by the oblique stretching step is 20 to 60 μm, preferably 10 to 60 μm, more preferably 10 to 50 μm from the viewpoints of mechanical strength and thinning of the display device, and particularly preferably 15~35μm. Further, the thickness of the elongated obliquely stretched film in the width direction is uneven, which affects the possibility of winding, and is preferably 3 μm or less, more preferably 2 μm or less.

[2-5-1-4] Heat treatment step

Next, the obliquely extending film (cast film) which is obliquely stretched is subjected to a heat treatment process of the following (i) or (ii) to obtain a heat treatment step of the first optical film.

(i) for the end of the film after film formation, at 180~220 °C In the range of embossing, the cast film is wound into a roll, and heat-treated for 3 to 5 days under conditions of 60 to 80 ° C and 20% RH or less.

(ii) The film formed and stretched is conveyed at a tension of 120 to 150 N by a conveyance roller, and the film is heated at 140 to 170 ° C for 40 to 600 seconds by a conveyance roller.

In this manner, the film in which the obliquely stretched film is wound or the state in which the tension is applied is fixed and heat-treated, whereby the film can be thermally corrected, and the dimensional change rate L (θ) of the first optical film in the slow axis direction and The dimensional change rate L (θ + 90) in the direction orthogonal to the slow axis can be adjusted to satisfy the values of the above formulas (1) and (2).

The heat treatment of (i) and (ii) will be described below.

((i) heat treatment)

In the heat treatment of the above (i), the embossing of the embossed portion is first applied to both end portions in the width direction of the film obtained after the oblique stretching. The embossed portion refers to a pattern in which a film having a fixed width and a small continuous unevenness is provided on the film in order to prevent the back surface and the surface of the wound film from being completely adhered to each other before the film having a long shape is wound. When one surface (for example, the upper surface) of the film protrudes in a convex shape, the other surface (for example, the lower surface) of the film is formed in a concave shape corresponding to the convex shape.

In order to perform embossing, an embossing apparatus including an embossing roller and a back roller disposed opposite to the embossing roller via a film is preferably used for embossing.

The roller diameter of the embossed roller is preferably in the range of 5 to 20 cm, more preferably in the range of 6 to 15 cm. When the diameter of the roller of the embossed roller exceeds 20 cm, the distance between the heat source (disposed inside the embossed roller) and the surface of the embossed roller is too large, so that the surface of the embossed roller sometimes has uneven temperature. Therefore, the formed embossed portion generates a portion having a high modulus of elasticity and a portion having a low modulus, and a portion having a low modulus of elasticity is liable to collapse. When the roll diameter of the embossed roller is less than 5 cm, the rotating shaft vibrates, and the height of the convex portion formed by the embossing is easily deviated. The embossed portion formed higher than the set height has a tendency to collapse.

The material of the back pressure roller is preferably made of metal for the reason that the film on which the embossed portion is formed is uniformly cooled. The type of metal is preferably, for example, SUS, titanium, stainless steel, chrome plating, copper or the like. The back pressure roller made of metal, for example, is more likely to uniformly cool the film than the back pressure roller made of rubber, so that the cellulose ester is easily crystallized uniformly, and an embossed portion having high strength (high modulus of elasticity) can be formed.

The clearance between the embossed roller and the back pressure roller may be about 1 to 30 μm, preferably about 1 to 15 μm. The nip pressure caused by the embossing roller and the back pressure roller can be about 100 to 10000 Pa.

The both ends of the width direction of the film are embossed by the embossing roller and the back pressure roller at both ends in the width direction of the film.

The surface temperature of the embossed roller is preferably in the range of 150 to 350 ° C, more preferably in the range of 160 to 300 ° C, and particularly preferably in the range of 180 to 220 ° C. When the surface temperature of the embossed roller is in the range of 150 to 350 ° C, the film can be sufficiently melted, and even after cooling, the cellulose ester can be sufficiently crystallized. It is easy to form a high-strength embossed portion. Further, the film is not excessively melted, and the melt of the film is prevented from adhering to the embossed roller.

When the first optical film is formed at both end portions in the width direction of the film, when the embossed portion is formed by the embossing roller, the surface temperature of the embossed roller on both sides is set to a temperature difference within a range of 5 to 20 ° C. It is preferable to form the embossed portion. Since the first optical film is obliquely extended and has an anisotropy in the elastic modulus at both end portions in the film width direction, in order to eliminate the difference in the elastic modulus, the collapse resistance of the convex portion of the embossed portion is uniform, and the elastic modulus is low. The end portion is formed by a high-temperature embossing roller to form an embossed portion, and an end portion having a high elastic modulus, and an embossing roller having a surface temperature of the embossed roller set to a low temperature within a range of 5 to 20 ° C, forming an embossed portion good. The surface temperature difference is more preferably in the range of 7 to 15 °C.

The surface temperature of the back pressure roller varies depending on the surface temperature of the embossed roller, but is preferably in the range of 30 to 100 ° C, more preferably in the range of 50 to 80 ° C. When the surface temperature of the back pressure roller is in the range of 50 to 100 ° C, the film is not rapidly cooled, so that the cellulose ester is easily crystallized uniformly, and an embossed portion having a high modulus of elasticity can be obtained. Moreover, not only the cellulose ester contained in the film is easily cooled, but also crystallization is facilitated, and thermal expansion of the film is suppressed, and the surface of the film in the vicinity of the embossed portion is prevented from being wavy. When the surface of the film near the embossed portion is wavy, the films adhere to each other, and the film becomes easily torn.

The conveying speed of the film during embossing is preferably in the range of 50 to 120 m/min. When the conveying speed of the film is in the range of 80 to 120 m/min, the productivity is high, and the pressure of the embossed roller or the embossed roller or the back Since the heat of the roller is easily transmitted to the film uniformly, the cellulose ester contained in the film is uniformly crystallized, and a high-strength embossed portion can be obtained.

In other words, in order to form an embossed portion which is less likely to collapse, the cellulose ester is sufficiently melted by the embossing roller, and the cellulose ester which is melted by the back pressure roller is slowly cooled to make crystallization important. Therefore, at least two or more of (1) the surface temperature of the embossed roller, (2) the surface temperature of the back pressure roller, (3) the roller diameter of the embossed roller, and (4) the material of the back pressure roller are various combinations. To adjust better. Wherein, (1) the surface temperature of the embossed roller and (2) the surface temperature of the back pressure roller are respectively adjusted to the above range, and it is more preferable to adjust the (3) embossed roller diameter to the aforementioned range, which is particularly preferable. To select (4) the material of the back pressure roller.

Next, the heat treatment of (i) is performed by embossing the end portion of the film and then winding it into a roll shape, and heat-treating at a temperature of 60 to 80 ° C and 20% RH or less. day.

The winding of the film can be carried out using a winder.

Further, the winding method of the film is not particularly limited, and for example, a constant torque method, a constant tension method, a taper tension method, or the like can be used.

The winding tension when winding the film can be about 50 to 170N.

The period of the heat treatment may be appropriately determined by the set temperature. Usually, it is set to be relatively low temperature, and it is preferable that the heat treatment effect of the outer portion of the roll, the center portion of the roll, and the core portion is not biased.

In order to stabilize the heat treatment, it is preferable to carry out the heat treatment in a place where the temperature and humidity can be adjusted, and it is preferable to carry out heat treatment in a clean room such as a dust-free room.

Roll when the antireflection film is wound into a roll The core is not particularly limited as long as it is a core on the cylinder, and is preferably a hollow plastic core. The plastic material is preferably a heat-resistant plastic which is resistant to heat treatment, and examples thereof include phenol resin, xylene resin, and melamine resin. , resin such as polyester resin or epoxy resin. Further, it is preferably a thermosetting resin reinforced with a filler such as glass fiber.

The number of windings of these winding cores is preferably 100 or more, more preferably 500 or more, and the winding thickness is preferably 5 cm or more.

As described above, when the long-roll film is subjected to the heat treatment in the wound state, the roller is preferably rotated, and the rotation speed is preferably 1 minute or less and 1 or less, and the film can be continuously and intermittently rotated. Further, in the heating period, it is preferable that the rewinding of the roller is performed at least one or more.

Since the film wound on the long roll wound around the core is rotated in the heat treatment, it is preferable to provide a rotary table for use in the heat treatment chamber.

When the rotation is intermittent, the stop time is preferably within 10 hours, the stop position is preferably in the circumferential direction, and the stop time is preferably within 10 minutes. The best is continuous rotation.

The rotation speed of the continuous rotation and the time required for one rotation are preferably 10 hours or less. When the speed is high, the device is burdened, and therefore, it is preferably in the range of 15 minutes to 2 hours.

In the case of a trolley having a rotating function, it is also preferable to rotate the optical film roll during movement or storage. In this case, as a black band countermeasure generated by a long storage period, the rotation can be performed. Produce effective functions.

Moreover, the heat treatment of (i) will be wound into a thin roll. It is preferable that the film is subjected to the above heat treatment in a state of being covered with a wet sheet. In other words, the film is wound into a roll, and the resin film, preferably a resin film, is coated with a moisture-proof sheet coated with aluminum, and then the reel portion is fixed by a rope or a rubber tape to perform the above heat treatment. good.

In this way, when the film wound into a roll shape is subjected to heat treatment, the humidity is easily maintained at a temperature of 20% RH or less, and moisture absorption of the film or adhesion of foreign matter can be suppressed, and high quality can be produced. 1 optical film.

Specific examples of the packaging form of the film include, for example, a circumferential surface of the film wound in a cylindrical shape and a total of both end faces in the axial direction, and are covered with a sheet-like packaging material, and the roll circumference of the packaging material. Both end portions of the direction overlap each other, and the joint portions of the end portions of the wrapping materials are fixed by a tape or the like. By this aspect, the portions where the ends of the packaging material are in contact with each other are substantially free of gaps to prevent intrusion of garbage or the like into the interior. When both ends of the core-shaped film in the axial direction protrude from the outer side of the winding core, the end surface of the end portion and the axial end portions of the packaging material are fixed by a rope, a rubber tape or the like to form a slight seal. The shape of the state is better. Compared with the conventional ones, the left and right end portions are not fixed by tape, and there is substantially no gap therebetween, and when the inside is sealed, the core portion is fixed by a rope or a rubber belt or the like, and the reel body is stored during transportation or transportation. Appropriate moisture absorption and moisture wicking are preferred in terms of improving the optical properties and uniformity of physical properties of the optical film.

Examples of such a packaging material include a film of a polyolefin-based synthetic resin such as polyethylene or polypropylene, or a film of a polyester-based synthetic resin such as polyethylene terephthalate or polyethylene naphthalate. . Also, package The thickness of the material to be filled is preferably 10 μm or more from the viewpoint of maintaining moisture permeability, and is preferably 100 μm or less from the viewpoint of handling such as rigidity. Further, since the moisture permeability of the packaging material changes depending on the thickness of the synthetic resin film constituting the packaging material, the moisture permeability of the packaging material can be appropriately adjusted by adjusting the thickness of the synthetic resin film.

Here, when the moisture permeability of the packaging material is 10 g/m ² or less per day as specified in JIS Z0208, it is possible to prevent deterioration of the shape of the roll or malfunction of foreign matter, and it is less likely to cause damage due to the above problem. good.

Further, the package form of the optical film of the optical film of the present invention is preferably a package in which the roll of the optical film is packaged in a moisture permeability of 5 g/m ² or less per day as defined in JIS Z0208, more preferably The packaging material is packaged with a moisture permeability of 1 g/m ² or less. As a result, it is possible to suppress deterioration during storage in a storage state such as storage and transportation of the film (deterioration of the roll shape, occurrence of adhesion failure between the films, and foreign matter failure).

In addition, a packaging material having a moisture permeability of 5 g/m ² or less to 1 g/m ² or less per day as defined in JIS Z0208 may, for example, be a polyolefin-based synthetic resin film in which polyethylene or polypropylene is laminated and aggregated. a composite material of a polyester synthetic resin film such as ethylene terephthalate or polyethylene naphthalate, or a metal such as aluminum deposited on the film, or a film of metal is bonded and laminated Composite materials, etc. The thickness of the packaging material composed of the composite material is preferably 1 μm or more from the viewpoint of maintaining moisture permeability, and is preferably 50 μm or less from the viewpoint of handling such as rigidity. Further, since the moisture permeability of the packaging material changes depending on the thickness of the composite material, the moisture permeability of the packaging material can be appropriately adjusted by adjusting the thickness.

In particular, a composite material of a polyolefin-based synthetic resin film such as polyethylene or polypropylene and a polyester-based synthetic resin film such as polyethylene terephthalate or polyethylene naphthalate, or the like, or the like The film is vapor-deposited with a metal such as aluminum, or a composite material in which a metal film is joined and laminated, and high moisture permeability prevention property is obtained, and the material is lightweight, so that it is particularly suitable for use in operation.

The above-mentioned packaging material exhibits the above-described effects by winding the roll of the optical film of the present invention at least one weight, but it is also possible to wind two or more.

By performing the heat treatment step in this manner, the film is thermally corrected, and the dimensional change rate is reduced, and the dimensional change rate L(θ) in the slow axis direction and the dimensional change rate L (θ+) in the direction orthogonal to the slow axis can be obtained. 90) A first optical film satisfying the above formulas (1) and (2).

((ii) heat treatment)

In the heat treatment of the above (ii), the film obtained by obliquely stretching is subjected to a tension of 120 to 150 N at a temperature of 140 to 170 ° C, and is conveyed by a transfer roller of 300 to 600 for 40 to 600 seconds. Transfer and heat treatment.

The heat treatment in the above (ii) may be a heat treatment in any configuration as long as it is a device having a transfer roller group that can apply the tension to the film and can be heated in the above temperature range. For example, it is preferable to use a device having a transfer roller of 300 to 600 rolls for heat treatment.

By performing the heat treatment step in this manner, the film is thermally corrected and the dimensional change rate is reduced. Thereby, the first optical film satisfying the above formulas (1) and (2) can be obtained by the dimensional change rate L(θ) in the slow axis direction and the dimensional change rate L (θ+90) in the direction orthogonal to the slow axis.

[2-5-2] Method for film formation by melt casting

When the first optical film is produced by a melt casting film forming method, the composition containing an additive such as a resin or a plasticizer is heated and melted to a temperature at which fluidity is exhibited, and then the melt containing the fluidity cellulose ester is melted. The material is cast.

The molding method of heating and melting can be classified into a melt extrusion molding method, a pressure molding method, a blow molding method, an injection molding method, a blow molding method, an extension molding method, and the like. Among these molding methods, a melt extrusion method is preferred from the viewpoints of mechanical strength and surface precision. The plurality of raw materials used in the melt extrusion method are usually preliminarily kneaded to be granulated.

Granulation can be carried out using known methods, for example, dry cellulose oxime, plasticizer and other additives can be supplied to the extruder by means of a feeder, and then sifted using a uniaxial or biaxial extruder, and then by a die. Squeeze into strips, cut off by water or air cooling.

The additives can be mixed before being fed to the extruder or each can be supplied as an individual feeder. Further, in order to uniformly mix a small amount of an additive such as a fine particle or an antioxidant, it is preferred to mix it beforehand.

The extruder used for granulation preferably suppresses the shearing force without deteriorating the resin (reducing molecular weight, coloring, gel formation, etc.) The method of granulating as low temperature as possible is preferred. For example, in the case of a twin-screw extruder, it is preferred to use a deep groove type screw shaft to rotate in the same direction. In terms of kneading uniformity, it is preferably a bite type.

Next, film formation was carried out using the pellets obtained above. Of course, the powder of the raw material can be directly supplied to the extruder without being granulated, and after heating and melting, the film can be directly formed into a film.

The granules are uniaxially or biaxially extruded, and the melting temperature during extrusion is in the range of 200 to 300 ° C, and the foreign matter is removed by filtration using a leaf disk filter or the like, and then cast by a T mold. In the form of a film, the film is held by a cooling roll and an elastic contact roll, and solidified on a cooling roll.

When the feed hopper is introduced into the extruder, it is preferably carried out under vacuum or under reduced pressure or in an inert gas atmosphere to prevent oxidative decomposition and the like.

The extrusion flow rate is preferably carried out by introducing a gear pump or the like. Further, it is preferable to use a stainless steel fiber sintered filter for removing the filter for foreign matter. The stainless steel fiber sintered filter is formed by twisting the stainless steel fiber body in a complicated state and compressing it so that the contact portion is sintered and integrated, and the density is changed by the thickness and compression amount of the fiber, and the filtration precision can be adjusted.

Additives such as plasticizers or microparticles may be mixed with the resin in advance or mixed in the middle of the extruder. For uniform addition, it is preferred to use a mixing device such as a static mixer.

The film temperature on the contact roll side when the film is caught by the cooling roll and the elastic contact roll is preferably Tg or more and Tg+110 ° C or less of the film. Within the scope. For the elastic contact roller having an elastomer surface for this purpose, a known elastic contact roller can be used. The elastic contact roller is also called a rolling revolving body, and can be used by a commercially available person.

When the film is peeled off by the cooling roll, it is preferable to control the tension to prevent the film from being deformed.

Further, after the film obtained as described above is passed through the step of contacting the cooling roll, the stretching process is applied by the lateral stretching step and the oblique stretching step.

The method of stretching is preferably a known roll stretcher or tenter or the like. The stretching temperature is usually preferably carried out in a temperature range of Tg to (Tg + 60) °C of the resin constituting the film.

[3] 2nd optical film

The second optical film of the present invention is provided to face the other of the polarizers. The second optical film is preferably extended in the longitudinal direction or the width direction, and the slow axis is preferably parallel or orthogonal to the absorption axis of the polarizer.

Since the material of the second optical film can be the same as that of the first optical film described above, the description thereof is omitted, and cellulose acetate or cellulose acetate propionate is particularly preferable.

The matters other than the above are the same as those of the first optical film, and thus the description thereof will be omitted.

[4] Other constituent layers

The polarizing plate is matched between the first optical film and the second optical film. The surface on the identification side of the optical film on the identification side may also have a functional layer. The functional layer may be provided with a hardened layer or an anti-glare layer composed of, for example, an ultraviolet curable resin.

For the hardened layer or the anti-glare layer used as the functional layer, for example, a hardened layer described in, for example, JP-A-2003-114333, JP-A-2004-203009, JP-A-2004-354699, and JP-A-2004-354828, or Anti-glare layer.

[4-1] hardened layer

The hardened layer is preferably a cured product containing a reactive wire curable compound, and the active wire curable compound is preferably a component containing a monomer having an ethylenically unsaturated double bond. The active-curable compound is preferably an ultraviolet curable compound or an electron beam curable compound, and a compound which is cured by ultraviolet irradiation is excellent in mechanical film strength (scratch resistance, pencil hardness).

The ultraviolet curable compound is preferably, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, or an ultraviolet curable polyol acrylate. A resin or an ultraviolet curable epoxy resin. Among them, an ultraviolet curable acrylate resin is preferred.

The hard layer has a dry layer thickness and an average layer thickness of 0.01 to 20 μm, preferably 0.5 to 10 μm. More preferably, it is in the range of 0.5 to 5 μm.

For the coating method of the hardened layer, for example, gravure coating can be used. A known method such as a machine, a dip coater, a reverse coater, a wire coating bar, a die coater, or an inkjet method. After the hardened layer composition is applied, the active wire (also referred to as UV hardening treatment) is dried and dried to be cured, and further, if necessary, heat treatment may be performed after curing.

[4-2] Anti-glare layer

The anti-glare layer is a layer that blurs the image reflected on the surface of the film substrate or the light of the external light, and is used when an image display device such as a liquid crystal display, an organic EL display, or a plasma display is used. Or the reflection image is reflected in the functional layer that does not affect it. The anti-glare layer may also have a hardened layer.

The anti-glare layer is preferably used in the active-line-curable resin used for the hardened layer, and it is preferable to add the following fine particles to be dispersed. Examples of the fine particles include fine particles such as inorganic fine particles or organic fine particles, and examples of the inorganic fine particles include cerium oxide, magnesium oxide, and calcium carbonate. Further, examples of the organic particles include polymethacrylic acid methacrylate resin powder, acrylonitrile-based styrene resin powder, polymethyl methacrylate resin powder, polystyrene resin powder, or melamine resin powder.

The arithmetic mean roughness Ra (JIS B0601:1994) of the anti-glare layer is in the range of 0.3 to 1.5 μm, preferably from the viewpoint of imparting anti-glare property, and more preferably in the range of 0.35 to 1.3 μm, particularly preferably 0.5. Within the range of ~1.3 μm. When it is in the above range, it is preferable to obtain an antiglare layer which satisfies the antiglare property and the antiglare layer and has a high hardness (4H or more) even if it is a film.

"Manufacturing method of polarizing plate"

The first optical film of the present invention extends obliquely, and the angle θ between the slow axis and the absorption axis of the polarizer is in the range of 30 to 60°, and the transmission axis (or absorption axis) is wound in the shape of a roll and a length in the longitudinal direction. The polarizer is attached to form a long-shaped polarizing plate.

In the case where the heat treatment of (ii) is performed in the heat treatment step of the first optical film, the method for producing the polarizing plate of the present invention further preferably has a step of removing the embossed portion of the first optical film.

Preferably, the polarizing plate is a first optical film and a second optical film holding polarizer of the present invention.

The optical film and the polarizer are not particularly limited, and the optical film may be subjected to a saponification treatment, and then a completely saponified polyvinyl alcohol-based adhesive may be applied. In addition, it is also possible to use an active energy ray-curable adhesive or the like. However, it is preferable to use a photocurable adhesive from the viewpoint that the obtained adhesive layer has a high modulus of elasticity and is easy to suppress deformation of the polarizing plate. Hehe.

A preferred example of the photocurable adhesive agent is, for example, Japanese Patent Laid-Open Publication No. 2011-028234, which contains (α) a cationically polymerizable compound, (β) a photocationic polymerization initiator, and (γ) for more than 380 nm. The long-wavelength light shows a photo-curable adhesive composition of each of the components of the (δ) naphthalene-based photo-sensitizing aid. However, a photocurable adhesive other than these may be used.

Hereinafter, a polarizing plate using a photocurable adhesive will be described An example of a manufacturing method. The polarizing plate can be manufactured by a manufacturing method comprising the steps of: (1) performing a processing step before the surface of the polarizing mirror of the optical film is easily followed, and (2) at least one side of the bonding surface of the polarizing mirror and the optical film. a step of applying an adhesive for applying the photocurable adhesive described below, (3) a step of bonding the polarizer to the optical film via the obtained adhesive layer, and (4) applying the paste via the adhesive layer A hardening step of hardening the adhesive layer in a state in which the polarizer and the optical film are combined. (1) The previous processing steps can also be carried out as necessary.

(pre-processing steps)

The pre-treatment step is performed on the subsequent surface of the optical film and the polarizer for easy subsequent processing. When the optical film is respectively adhered to both sides of the polarizer, the subsequent processing of the optical film and the bonding surface of the polarizer is performed. Examples of the subsequent treatment include corona treatment, plasma treatment, and the like.

(adhesive coating step)

The subsequent coating step is applied to at least one of the bonding surfaces of the polarizing mirror and the optical film, and the photocurable adhesive is applied. When the photocurable adhesive is directly applied to the surface of the polarizer or the optical film, the coating method is not particularly limited. For example, various coating methods such as a doctor blade type, a wire bar type, a die coater, a double roll coating, and a gravure coater can be used. Further, after the photocurable adhesive is cast between the polarizer and the optical film, a method in which the pressurization is uniformly performed by a roller or the like may be used.

(Fitting step)

After the photocurable adhesive is applied in this manner, it is supplied to the bonding step. This bonding step, for example, in the case of applying the photocurable adhesive to the surface of the polarizer in the previous coating step, overlaps the optical film there. In the case where the previous coating step is applied to the surface of the optical film with a photocurable adhesive, the polarizer is superposed there. Further, when the photocurable adhesive is cast between the polarizer and the optical film, the polarizer and the optical film are superimposed in this state. In the case where the optical film is bonded to both surfaces of the polarizer, when a photocurable adhesive is used on both surfaces, the optical film is superposed on both surfaces of the polarizer via a photocurable adhesive. Further, in this state as a general state, pressurization is performed by a roll or the like from both sides. The material of the roller can be metal or rubber. Configure the rollers on both sides to be the same material and different materials.

(hardening step)

The hardening step is to irradiate the active energy ray to the uncured photocurable adhesive to harden the adhesive layer containing the epoxy compound or the propylene oxide compound. Thereby, the superposed polarizing lens is bonded to the optical film through the photocurable adhesive. In order to bond the optical film to both surfaces of the polarizer, the optical fiber film is irradiated from either side of the optical film on both sides of the polarizer via the photocurable adhesive, thereby contributing to the light on both sides. The hardenable adhesive hardens at the same time.

As the active energy ray, visible light, ultraviolet light, X-ray, electron beam or the like can be used. Since the operation is easy and the curing speed is sufficient, it is generally preferred to use an electron beam or an ultraviolet ray.

The irradiation conditions of the electron beam may be any suitable conditions as long as the conditions of the above-mentioned adhesive can be cured. For example, electron beam irradiation, the acceleration voltage is preferably in the range of 5 to 300 kV, more preferably in the range of 10 to 250 kV. When the accelerating voltage is less than 5kV, the electron beam will not reach the adhesive and cause insufficient hardening. When the accelerating voltage exceeds 300kV, the electron beam rebounds due to the excessive penetration of the sample. For transparent optical film or polarizer There is a flaw in the damage. The amount of irradiation line is in the range of 5 to 100 kGy, preferably in the range of 10 to 75 kGy. When the amount of irradiation line is less than 5 kGy, the adhesive becomes insufficiently hardened. When it exceeds 100 kGy, the transparent optical film or the polarizer is damaged, and mechanical strength is lowered or yellowed, and specific optical characteristics are not obtained.

When the ultraviolet irradiation condition is a condition capable of curing the above-mentioned adhesive, any appropriate conditions can be employed. The amount of ultraviolet light to be irradiated is preferably in the range of 50 to 1,500 mJ/cm ² , more preferably in the range of 100 to 500 mJ/cm ² .

In the polarizing plate obtained above, the thickness of the adhesive layer is not particularly limited, but is usually in the range of 0.01 to 10, preferably 0.5 to 5 μm.

"Liquid Crystal Display Device"

Fig. 3 is a cross-sectional view showing a schematic configuration of a liquid crystal display device 10 of the present embodiment. The liquid crystal display device 10 includes a liquid crystal cell 11 and a polarizing plate 12 disposed on the identification side with respect to the liquid crystal cell 11, and a polarizing plate 13 disposed on the opposite side to the identification side with respect to the liquid crystal cell 11, and a polarizing plate 13 The board 13 is disposed on the backlight side 14 on the opposite side to the identification side and on the front side panel 15 on the identification side with respect to the polarizing plate 12. The liquid crystal cells 11 are formed by sandwiching a liquid crystal layer with a pair of substrates. The liquid crystal cell 11 has a plurality of pixels arranged in a matrix, and the driving of each pixel is ON/OFF by a switching element such as a TFT (Thin Film Transistor).

The front panel 15 serves as a protector for the liquid crystal display device 10, a transparent substrate made of glass or resin (for example, acrylic), or a touch panel module. It is preferable that a filler (not shown) made of, for example, an ultraviolet curable resin is filled between the front panel 15 and the polarizing plate 12. By providing a filler, an air layer is formed between the front panel 15 and the polarizing plate 12, and the interface between the front panel 15 and the air layer and the light reflection at the interface between the polarizing plate 12 and the air layer are suppressed, and the display image can be improved. Identification.

In the polarizing plate 12, the polarizing plate of the present invention has a polarizing mirror 21 that is polarized by a specific linear direction, and a first optical film 22 that is disposed on the identification side via an adhesive layer or the like with respect to the polarizing mirror 21, and is further disposed. The function layer 23 on the identification side. The functional layer 23 described above is composed of, for example, a cured layer or an anti-glare layer composed of an ultraviolet curable resin. Further, the polarizing plate 12 is provided with the second optical film 24 disposed on the liquid crystal cell 11 side via the adhesive layer or the like with respect to the polarizing mirror 21.

The polarizer 21 is obtained by, for example, dyeing a polyvinyl alcohol film with a dichroic dye and extending it at a high magnification. After the alkali mirror (also referred to as saponification treatment), the polarizer 21 is bonded to the first optical film 22 via the adhesive layer or the like, and the second optical film 24 is bonded to the other surface via the adhesive layer or the like.

The layer is, for example, a layer composed of a polyvinyl alcohol adhesive (PVA adhesive, water paste), but may be a layer composed of an ultraviolet curing type adhesive (UV adhesive). These adhesives are applied to the surface in the form of a liquid, and after application, they are cured by drying or ultraviolet irradiation, and the two are followed. In other words, the subsequent layer changes from the liquid state, and the polarizer 21 and the first optical film 22, the polarizer 21, and the second optical film 24 are respectively attached. In this way, the layer is changed from the state of the liquid, and the two subsequent viewpoints are not changed, and the adhesion layer of the two layers (the flaky adhesive layer having the adhesive on the substrate) different.

The layer thickness of the layer is preferably in the range of more than 0.1 μm and less than 5 μm. At this time, the polarizing plate 12 can be made thinner than the configuration using an acrylic adhesive (having a thickness of about 10 μm).

The first optical film 22 is preferably provided with a layer containing a transmitted light and having an in-plane retardation of about 1/4 of a wavelength, and is preferably a cellulose ester film having a thickness of 20 to 60 μm which is obliquely extended. The angle (inclination angle) θ between the slow axis of the first optical film 22 and the absorption axis of the polarizing mirror 21 is in the range of 30 to 60°, whereby the linear light is polarized by the polarizing mirror 21, and the first optical film 22 is used. It is converted into circular or elliptically polarized light.

In the case where the hard layer constitutes the functional layer 23, the surface of the polarizing plate 12 can be protected by the hardened layer. The hardened layer may contain an organic compound having an ultraviolet absorbing function. As such an organic compound (organic UV absorber), for example, TINUVIN 928 (manufactured by BASF JAPAN Co., Ltd.) can be used.

The second optical film 24 is a cellulose ester having a film thickness of 20 to 60 μm. The film is provided as a film for protecting the inner side of the polarizer 21. The second optical film 24 can also be provided as an optical film having a retardation film having a desired optical compensation function.

The polarizing plate 13 has a polarizing mirror 31 that is polarized by a specific linear direction, an optical film 32 that is disposed on the side of the identification side (the liquid crystal cell 11 side) via the adhesive layer, and a polarizing mirror 31 with respect to the polarizing mirror 31. The optical film 33 is disposed via the adhesive layer on the opposite side (backlight side) of the identification side. The polarizers 21 and 31 are arranged in a state of orthogonal polarization. Further, the constituent materials of the polarizer 31 and the optical films 32 and 33 can be the same as those of the polarizer 21 and the second optical film 24.

As described above, in the polarizing plate 12 on the identification side, the first optical film 22 and the second optical film 24 located on both sides of the polarizing mirror 21 are both cellulose ester films composed of a film having a film thickness of 20 to 60 μm. The identification side of the polarizer 21 is disposed to be applied to the first optical film 22 which is obliquely extended. Therefore, the polarizing plate 12 due to the variation in moisture absorbed by the first optical film 22 and the second optical film 24 can be effectively suppressed. Warping.

Further, since the hard surface layer or the anti-glare layer of the functional layer 23 is provided on the identification side with respect to the first optical film 22, the surface of the polarizing plate 12 can be protected by the functional layer 23, or the anti-glare function can be exhibited.

Further, on the surface of the first optical film 22 on the side of the polarizer 21, an easy-adhesion layer for improving the adhesion of the first optical film 22 can be provided. The easy-adhesion layer is formed by facilitating subsequent processing of the surface of the first optical film 22. Easy to handle, for example, corona (discharge) treatment, plasma treatment, flame treatment, surface modification treatment, bright discharge treatment, ozone At least one of them may be carried out, such as a primer coating treatment or the like. Among these easy processes, corona treatment and plasma treatment are preferable as easy handling from the viewpoint of productivity.

Further, in the polarizing plate 12, a protective layer can be formed on the functional layer 23. The protective layer is preferably composed of an active energy ray-curable resin (for example, an ultraviolet curable resin) similar to the above-mentioned hardened layer. Thus, a protective layer is provided on the functional layer 23 to protect the surface of the functional layer 23.

Further, when both the overcoat layer and the functional layer 23 are hardened layers, two hardened layers are formed on one side of the first optical film 22, so that the surface protection of the polarizing plate 12 is surely achieved. Further, it is preferable that the protective layer is formed of a hardened layer which does not contain an organic compound having an ultraviolet absorbing function, or which has an organic compound having an ultraviolet absorbing function (% by mass) less than the functional layer 23. At this time, it is possible to further suppress the elution of the organic compound having the ultraviolet absorbing function contained in the functional layer 23 to the outside.

"Organic EL display device"

Fig. 4 is a cross-sectional view showing a schematic configuration of an organic EL display device 50 of the present embodiment. The organic EL display device 50 includes an organic EL light-emitting element 51, a polarizing plate 52 disposed on the identification side with respect to the organic EL light-emitting element 51, and a front panel 53 disposed on the identification side with respect to the polarizing plate 52. The organic EL light-emitting element 51 is formed on a substrate using glass or polyimide, and has a metal electrode, a TFT, an organic light-emitting layer, a transparent electrode (ITO or the like), an insulating layer, and an encapsulating layer in this order.

The polarizing plate 52 and the front panel 53 are connected to the above liquid crystal display device In the organic EL display device 50, the first optical film 62 of the polarizing plate 52 is disposed closer to the organic EL light-emitting element 51 than the polarizing mirror 61, and the first polarizing plate 12 is placed on the side of the organic EL light-emitting device 51. The optical film 64 is disposed closer to the identification side than the polarizer 61. Further, the functional layer 63 is disposed at a point on the identification side of the second optical film 64, and is configured differently from the liquid crystal display device 10.

In general, an organic EL display device includes an element (organic EL element) in which an illuminant of a metal electrode, an organic light-emitting layer, and a transparent electrode is sequentially laminated on a transparent substrate. Here, the organic light-emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer composed of a triphenylamine derivative or the like and a light-emitting layer composed of a fluorescent organic solid such as ruthenium or A combination of such a combination of the light-emitting layer and an electron injecting layer composed of an anthracene derivative or the like, or a combination of the hole injecting layer, the light-emitting layer, and the electron injecting layer is known.

The organic EL display device applies a voltage to the transparent electrode and the metal electrode, and the organic light-emitting layer is injected into the hole and the electron, whereby the energy generated by the recombination of the hole and the electron excites the fluorescent substance. When the excited fluorescent material returns to the substrate state, the principle of light is emitted to emit light. The recombination mechanism on the way, similarly to the general diode, can also imagine that the current and the luminous intensity are applied to the applied voltage, and the nonlinearity accompanying the rectifying property is exhibited.

In an organic EL display, in order to extract light emitted from the organic light-emitting layer, at least one of the electrodes must be transparent. Usually, a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. Preferably. Further, in order to facilitate electron injection and improve luminous efficiency, it is important to use a substance having a small work function for the cathode, and a metal electrode such as Mg-Ag or Al-Li is usually used.

The polarizing plate of the present invention can be applied to an organic EL display device having a screen size of 20 inches or more, that is, a large screen having a diagonal distance of 50.8 cm or more.

In the organic EL display device having such a configuration, the organic light-emitting layer is formed of an extremely thin film having a thickness of about 10 nm. Therefore, the organic light-emitting layer is also the same as the transparent electrode, and is almost completely transparent. As a result, when the non-light-emitting period is incident on the surface of the transparent substrate, the transparent electrode and the organic light-emitting layer are transmitted, and the light reflected by the metal electrode is emitted from the surface side of the transparent substrate. Therefore, when it is externally recognized, the display surface of the organic EL display device is seen. It looks like a mirror.

An organic EL display device including a transparent electrode on the surface side of the organic light-emitting layer that emits light by applying a voltage, and an organic EL element formed of a metal electrode on the back side of the organic light-emitting layer is provided in a transparent polarizing plate. On the surface side (identification side) of the electrode, the light passing through the circular polarizer passes through the transparent substrate, the transparent electrode, and the organic film, and is reflected by the metal electrode, and then transmitted through the organic film, the transparent electrode, and the transparent substrate, and is again recrystallized by the circular polarizing plate. Since the linear polarization is orthogonal to the polarization direction of the polarizing plate, the polarizing plate cannot be transmitted. As a result, the mirror surface of the metal electrode can be completely shielded.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention Not limited to this. In the examples, the expression "parts" or "%" is used, but when it is not specifically stated, it means "parts by mass" or "% by mass".

[Example 1] "Production of Polarizing Plate 101"

<Production of the first optical film>

A first optical film (λ/4 film) composed of a cellulose ester film was produced by the following method.

(modulation of fine particle dispersion)

The mixture was stirred and mixed for 50 minutes with a dissolver, and then dispersed by a Manton-Gaulin homogenizer.

<Modulation of Microparticle Addition Liquid>

According to the following composition, the fine particle dispersion was gradually added while sufficiently stirring in a dissolution tank containing dichloromethane. Further, it is dispersed by an attritor to make the particle diameter of the secondary particles a specific size. Further, it was filtered with FINEMET NF manufactured by Nippon Seisaku Co., Ltd. to prepare a fine particle addition liquid.

(main glue)

The main dope of the following composition was prepared. First, dichloromethane and ethanol were added to the pressure dissolution tank. Cellulose acetate was added while stirring in a pressure dissolution tank in which a solvent was placed. This was heated, and after stirring, it was completely dissolved, and this was filtered using the filter paper No. 244 of the Augmentation filter paper, and the main dope was prepared. Further, the following sugar esters and the following polyesters were synthesized by the following synthesis examples.

<Composition of main glue>

(synthesis of sugar esters)

The sugar ester is synthesized by the following steps.

In a four-headed conical flask equipped with a stirring device, a reflux condenser, a thermometer and a nitrogen gas introduction tube, 34.2 g of sucrose was charged (0.1 mol) 18) g (0.8 mol) of benzoic anhydride and 379.7 g (4.8 mol) of pyridine, and the nitrogen gas was bubbled out from the nitrogen gas introduction tube while stirring, and the temperature was raised, and the ester was allowed to stand at 70 ° C for 5 hours. Reaction.

Next, the inside of the conical flask was depressurized to 4 × 10 ² Pa or less, and the excess pyridine was distilled off at 60 ° C, and then the inside of the conical flask was depressurized to 1.3 × 10 Pa or less, and the temperature was raised to 120 ° C to distill off the benzene. The majority of the anhydride, the benzoic acid produced.

Finally, 100 g of water was added to the separated toluene layer, and after washing at room temperature for 30 minutes, the toluene layer was separated and taken out, and toluene was distilled off at 60 ° C under reduced pressure (4 × 10 ² Pa or less) to obtain a compound A- 1. A mixture of A-2, A-3, A-4 and A-5 (sugar ester).

After the obtained mixture was analyzed by HPLC and LC-MASS, A-1 was 1.3% by mass, A-2 was 13.4% by mass, A-3 was 13.1% by mass, A-4 was 31.7% by mass, and A-5 was 40.5. quality%. The average degree of substitution is 5.5.

(Measurement conditions of HPLC-MS)

1) LC department

Device: Japan Spectroscopic (column) column oven (JASCO CO-965), detector (JASCO UV-970-240nm), pump (JASCO PU-980), degaserator (degasser) (JASCO DG-980 -50)

Column: Inertsil ODS-3 particle size 5μm 4.6×250mm (made by GL Sciences)

Column temperature: 40 ° C

Flow rate: 1ml/min

Mobile phase: THF (1% acetic acid): H ₂ O (50:50)

Injection volume: 3μl

2) MS Department

Device: LCQ DECA (Thermo Quest system)

Ionization method: Electrospray ionization (ESI) method

Spray Voltage: 5kV

Capillary temperature: 180 ° C

Vaporizer temperature: 450 ° C

(synthesis of polyester)

The polyester was synthesized by the following procedure.

251 g of 1,2-propanediol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a thermometer, a stirrer, and reflux cooling. In a 2-L four-necked flask, the temperature was raised to 230 ° C while stirring in a nitrogen stream. The dehydration condensation reaction was allowed to proceed for 15 hours, and after the completion of the reaction, the unreacted 1,2-propanediol was distilled off at 200 ° C under reduced pressure to obtain a polyester. The polyester has an ester of benzoic acid at the end of the polyester chain formed by condensation of 1,2-propanediol, phthalic anhydride, and adipic acid. The acid value of the polyester was 0.10 and the number average molecular weight was 450.

(production of long film)

Next, a non-terminal tape casting device was used to uniformly cast (cast) on the stainless steel belt support.

The endless belt casting device uniformly casts the above main glue onto the stainless steel belt support. The solvent in the cast (cast) elongated film was evaporated on a stainless steel belt support, and peeled off from the stainless steel belt support (casting step). The obtained film was dried, and the residual solvent amount was 10% by mass, and then stretched at a stretching ratio of 1.15 times with respect to the original width in the width direction at 170 ° C using a tenter (lateral stretching step).

Then, the manufacturing apparatus shown in FIG. 1 was used for transport, and the alignment angle θ was 45°, the extension temperature was 185° C., and the stretching ratio was 1.7 times, and the elongated film was obliquely extended to form an elongated obliquely extending film (inclined stretching step). ).

Further, the heat treatment step is performed by performing the heat treatment of the above (i) or (ii).

In the case of the heat treatment of (i), the end portion of the film after the production is subjected to embossing in the range of 180 to 220 ° C, and then wound into a roll shape, 60 to 80 ° C, 20 Heat treatment for 3 to 5 days under conditions of %RH or less.

In Table 1, the heat treatment (i)-1 was embossed at 220 ° C, and wound into a roll-shaped film to prevent the wet sheet 3 from being wound up and coated, and heated at 60 ° C and 20% RH. Handle 3 days. Further, the heat treatment (i)-2 was embossed at 180 ° C, and wound into a roll shape to prevent the wet sheet 2 from being wound up and coated, and heated at 80 ° C under 5% RH. The 5th day. Also, heat treatment (i)-3

The embossing was carried out at 170 ° C, and the film was wound into a roll-shaped film to prevent the wet sheet 1 from being wound up and coated, and heat-treated at 50 ° C for 20% RH for 2 days (Comparative Example).

Further, the moisture-proof sheet was used to deposit a film of aluminum on a polyethylene resin film having a thickness of 30 μm.

In the case of the heat treatment of (ii), the produced film is conveyed by a transfer roller at a tension of 120 to 150 N, and the film is heat-treated at 140 to 170 ° C for 40 to 600 seconds via a transfer roller.

In Table 1, the heat treatment (ii)-1 was carried out by a transfer roller of 500 rolls, and the film was conveyed at a tension of 120 N while the film was heated at 140 ° C for 600 seconds. Further, the heat treatment (ii)-2 was carried out by a transfer roller of 500 rolls, and the film was conveyed at a tension of 120 N while the film was heated at 170 ° C for 40 seconds. Further, the heat treatment (ii)-3 was carried out by a transfer roller of 200 rolls, and the film was conveyed at a tension of 100 N while the film was heated at 120 ° C for 200 seconds (Comparative Example).

The production of the polarizing plate 101 in which the heat treatment step is a heat treatment of (ii)-1. By performing this heat treatment step, a roll of a 3000 m film as the first optical film can be obtained. This film had a thickness of 60 μm.

<Production of 2nd Optical Film>

A second optical film composed of a cellulose ester film was produced by the following method.

(modulation of fine particle dispersion dilution)

10 parts by mass of Aerosil R812 (manufactured by Nippon Aerosil Co., Ltd., primary average particle diameter: 7 nm, apparent specific gravity: 50 g/L), and 90 parts by mass of ethanol were stirred and mixed for 30 minutes with a dissolving rod, and Manton Gaulin using a high-pressure disperser was used. It is dispersed to prepare a fine particle dispersion.

88 parts by mass of dichloromethane was added to the fine particle dispersion obtained above under stirring, and the mixture was stirred and mixed for 30 minutes with a dissolving rod to be diluted. The obtained solution was filtered using a Polypropylene Winder Cartridge Filter TCW-PPS-1N manufactured by Advantech Toyo Co., Ltd. to obtain a fine particle dispersion diluent.

(modulation of in-line addition liquid)

36 parts by mass of the above-prepared fine particle dispersion diluted solution was stirred and added to 100 parts by mass of methylene chloride, and after stirring for 30 minutes, 6 parts by mass of diethylstilbene cellulose (acetamidyl substitution degree of 2.32) The weight average molecular weight of 270,000 was added while stirring, and the mixture was further stirred for 60 minutes. The obtained solution was filtered using Finemet NF manufactured by Nippon Seisaku Co., Ltd. to obtain an in-line addition liquid. The filter material uses a nominal filtration accuracy of 20 μm.

(modulation of glue)

The following components were placed in a closed container, and completely dissolved by heating and stirring. The resulting solution was filtered using a vane filter The main gel was obtained by filtration at a temperature of 40 ° C (boiling point of dichloromethane + 10 ° C). As the filter medium, the filter paper No. 244 made of the filter paper (strand) was used.

<Composition of main glue>

100 parts by mass of the cement slurry and 2.5 parts by mass of the wire-added solution were thoroughly mixed using an in-line mixer (Toray static in-line mixer Hi-Mixer, SWJ) to obtain a dope.

The following compounds were used as the above retardation increasing agent.

(film formation, extension, drying)

The obtained dope was uniformly cast on a support of a stainless steel belt using a belt casting apparatus under the conditions of a liquid temperature of 35 ° C and a width of 1.95 m and a final film thickness of 33 μm. On the stainless steel belt support, the organic solvent in the obtained dope film was evaporated to a residual solvent amount of 30% by mass, and after forming a web, the web was peeled off from the stainless steel belt support. The obtained web was further dried at 40 ° C for 30 seconds, and the residual solvent amount was 5% by mass. Then, the web was stretched to a width in the TD direction at 160 ° C using a tenter. 1.35 times.

After stretching with a tenter, it was allowed to relax at 130 ° C for 5 minutes, and then dried by a plurality of rolls at the drying zone. The drying temperature was 130 ° C and the conveying tension was 100 N/m. The obtained film was cut into a width of 1.6 m, and embossing was applied to both ends of the film by a width of 10 mm and a height of 5 μm, and an initial tension of 220 N/m and a final tension of 110 N/m were wound around a core of an inner diameter of 15.24 cm. A cellulose ester film of 4000 m and a dry film thickness of 33 μm was obtained as a second optical film. The retardation value Ro (550) in the in-plane direction of the obtained second optical film was 50 nm, and the retardation value Rt (550) in the film thickness direction was 130 nm.

<Production of polarizing plate>

The first optical film and the second optical film obtained as described above were bonded to both surfaces of a polarizing mirror to prepare a polarizing plate.

(production of polarizer)

The following polarizing mirror was produced in accordance with Example 1 of Patent No. 4691 205.

On the amorphous PET substrate, a laminate of a PVA layer film having a thickness of 7 μm was formed, and an extension laminate was prepared by an extension of an extension temperature of 130° C., and then the extension laminate was dyed with iodine or potassium iodide. The colored laminate was further extended by a boric acid water having a stretching temperature of 65 degrees to obtain an optical film laminate containing a PVA layer having a total stretching ratio of 5.94 times and extending integrally with the amorphous PET substrate. (Polarizer). In the amorphous PET substrate, the polarizer is bonded to the optical film, and then peeled off, and only the PVA layer (polarizing film) is used.

(modulation of photocurable adhesive)

After mixing the following components, the photocurable adhesive was prepared by defoaming. Further, the triarylphosphonium hexafluorophosphate was formulated in a 50% propylene carbonate solution, and the solid content of the triarylsulfonium hexafluorophosphate was shown below.

(Positive of polarizer and optical film)

On the first optical film, the prepared photocurable adhesive was applied using a micro gravure coater to a dry thickness of 5 μm to form a photocurable adhesive layer. The coating was carried out under conditions of a gravure roll #300 and a rotation speed of 140%/linear velocity.

Similarly, the photocurable adhesive having the above-described prepared photocurable adhesive was applied to a thickness of 2 μm on the second optical film to form a photocurable adhesive layer.

The first optical film on which the photocurable adhesive layer is formed is disposed on the surface of the polarizer on which the phototransformer is formed, and the second optical film on which the photocurable adhesive layer is formed is disposed on the other surface to obtain the first optical Laminate/photocurable adhesive layer/polarizer/photocurable adhesive layer/second optical film laminate. The obtained laminate was aligned in the longitudinal direction by a roll machine and attached in a roll-to-roll manner. As a result of the bonding, the slow axis of the first optical film is bonded to the absorption axis of the polarizer in an oblique direction of 45°, and the slow axis of the second optical film is bonded in parallel with respect to the absorption axis of the polarizer. .

An electron beam is irradiated from both sides of the bonded laminate to cure the photocurable adhesive layer to obtain a laminate. The linear velocity is 20 m/min, the acceleration voltage is 250 kV, and the illumination line amount is 20 kGy.

Further, a composition for an anti-glare layer having the following composition is prepared, and a composition for an anti-glare layer is applied onto a surface (on the side of the identification side) of the first optical film of the laminate to be produced by a gravure reverse coater. The film thickness after hardening was 5.0 μm. This was dried in an oven at 70 ° C for 60 seconds, and then irradiated with ultraviolet rays at an irradiation amount of 120 mJ/cm ² to cure the coating film to form an antiglare layer as a functional layer.

The polarizing plate 101 was fabricated as described above.

"Production of Polarizing Plates 102~113"

In the production of the polarizing plate 101, the angle θ between the first optical film and the slow axis of the absorption axis of the polarizer is changed to the value described in Table 1, and the heat treatment step is changed to the method described in Table 1, and the same operation is performed. Polarizing plates 102 to 113 were produced.

"Production of polarizing plate 114"

In the production of the polarizing plate 101, when the second optical film is bonded to the polarizing mirror, the slow axis of the second optical film is orthogonally bonded to the absorption axis of the polarizing mirror, and the polarizing plate 114 is also produced in the same manner.

Evaluation of Polarizers 101~114

The following evaluations were performed on the polarizing plates 101 to 114 produced as described above. In the evaluation of the following (3) to (6), the polarizing plates 101 to 114 were used in advance, and a liquid crystal display device and an organic EL display device were produced as described below, and the display device was used for evaluation. The results of each evaluation are shown in Table 1.

(Production of liquid crystal display device)

A commercially available 20-inch VA mode liquid crystal display device was used to peel off the polarizing plate on the identification side, and the polarizing plates 101 to 114 produced above were bonded to the substrate surface of the liquid crystal cell to fabricate a liquid crystal display device. At this time, the bonding of the polarizing plates 101 to 114 is such that the polarizing plate on the identification side to be bonded in advance is bonded in the same direction as the absorption axis. At this time, the second optical films of the polarizing plates 101 to 114 are on the liquid crystal cell side, and the polarizing plates 101 to 114 are disposed.

(Production of organic EL display device)

Using the polarizing plates 101 to 114, an organic EL display device was produced in the same manner as in paragraphs [0180] to [0186] of JP-A-2013-109869. At this time, the first optical films of the polarizing plates 101 to 114 are on the side of the organic EL light-emitting element, and the polarizing plates 101 to 114 are disposed.

(1) Measurement of dimensional change rate before and after the heat treatment step of the first optical film

By the measurement method described in the "Dimensional change rate of the first optical film", L(θ), L(θ) are measured before and after the heat treatment step of the first optical film used for each of the polarizing plates 101 to 114. +90), L (MD) and L (TD). The respective values of L(θ)/L(θ+90) and L(MD)/L(TD) are calculated from the measurement results.

(2) Measurement of the optical value of the first optical film

Using an automatic birefringence meter KOBRA-21AWR (manufactured by Oji Scientific Instruments Co., Ltd.) at 23 ° C. In the environment of 55% RH, the retardation values Ro and Rt of the first optical films used for the polarizing plates 101 to 114 were calculated by measuring the birefringence at each wavelength.

(3) Deformation of an image mounted in a liquid crystal display device

The produced liquid crystal display device was allowed to stand at 40 ° C for 90% RH for 100 hours, and then placed under conditions of 23 ° C and 55% RH, and the liquid crystal display device was observed as follows.

That is, the display screen is placed in a vertical direction with the liquid crystal display device at a height of 80 cm from the ground, and the fluorescent light (FLR40S.D/MX) is placed on the ceiling portion at a height of 3 m from the ground. A group of 40W × 2 is made by PANASONIC Co., Ltd., and 10 groups are arranged at intervals of 1.5 m. At this time, when the evaluator is on the front side of the display screen of the liquid crystal display device, the illuminator is placed on the ceiling and the rear side of the evaluator. To configure.

The liquid crystal display device was placed as described above, and the display screen of the liquid crystal display device was observed and evaluated based on the following criteria.

◎: See the fluorescent light as a straight line

○: I saw a few bends in the fluorescent light.

△: I saw the fluorescent lamp bent

×: I saw the great curvature of the fluorescent lamp.

(4) The visibility of the screen mounted on the liquid crystal display device

For each of the polarizing plates 101 to 114, 20 samples of the above liquid crystal display device were produced. Then, the durability test: After each sample of the liquid crystal display device was allowed to stand at 40 ° C and 90% RH for 100 hours, the difference in visibility was observed at the center of the screen and the peripheral portion of the screen using a polarizing microscope. The results were evaluated on the basis of the following criteria.

◎: Brightness improvement (up) (identification deterioration) in the peripheral portion, 0 in 20 samples

○: The brightness of the peripheral part is increased (deviation is degraded), and it is 1 or 2 in 20 samples.

△: The brightness of the peripheral part is increased (deviation is degraded), and it is 3 to 5 in 20 samples.

×: The brightness of the peripheral portion is increased (deterioration of visibility), and it is 6 or more among the 20 samples.

(5) Deformation of the device mounted in the case of the organic EL display device

The produced organic EL display device was allowed to stand at 40 ° C for 90% RH for 100 hours, and then placed at 23 ° C under a condition of 55% RH, and an organic EL display device was observed as described below.

In other words, the display screen of the organic EL display device is placed at a height of 80 cm from the ground, and the display screen is placed vertically upwards. On the ceiling portion at a height of 3 m from the ground, a white fluorescent light fluorescent lamp (FLR40S.D/) is used. MX PANASONIC Co., Ltd.) 40W × 2 is a group, and 10 groups are arranged at 1.5m intervals. At this time, when the evaluator is on the front side of the display screen of the organic EL display device, the illuminator is placed on the ceiling portion toward the rear of the evaluator.

The organic EL display device was placed as described above, and the display screen of the organic EL display device was observed and evaluated on the basis of the following criteria.

◎: See the fluorescent light as a straight line

○: I saw a few bends in the fluorescent light.

△: I saw the fluorescent lamp bent

×: I saw the great curvature of the fluorescent lamp.

(6) Identification of the screen mounted on the organic EL display device

The produced organic EL display device was allowed to stand at 40 ° C for 90% RH for 100 hours, and then placed under conditions of 23 ° C and 55% RH to observe an organic EL display device. The results were evaluated on the basis of the following criteria.

◎: When viewing the EL display device after production, you can't see the image of yourself or the background at all.

○: When watching the EL display device after production, I don’t see myself or Background image

△: When viewing the EL display device after production, the image of the display device and the image of itself or the background are seen, but the actual damage is low.

×: When viewing the EL display device after production, the image of the display device and the image of itself or the background are clearly seen, and the actual damage is present.

As shown in Table 1, the dimensional change rate L(θ) in the slow axis direction of the first optical film and the dimensional change rate L (θ+90) in the direction orthogonal to the slow axis satisfy the above formulas (1) and (2). When the polarizing plates 101 to 104, 109 to 112, and 114 of the present invention are mounted on a liquid crystal display device or an organic EL display device, the occurrence of deformation of the device is suppressed, and the visibility is also good. Therefore, the occurrence of physical deformation of the polarizing plate of the present invention is suppressed, whereby the above results can be obtained.

In order to obtain such a polarizing plate of the present invention, it is preferable to carry out the following heat treatment (i) and heat treatment (ii), that is, after the oblique stretching step, at the end of the film, at 180 to 220 ° C In the range where embossing is applied, the film is wound into a roll, and heat-treated for 3 to 5 days (i) or conveyed under conditions of 60 to 80 ° C and 20% RH or less. The roller is conveyed at a tension of 120 to 150 N, and the film is heated at 140 to 170 ° C for 40 to 600 seconds by heat transfer (ii).

On the other hand, the dimensional change rate L(θ) in the slow axis direction of the first optical film and the dimensional change rate L (θ+90) in the direction orthogonal to the slow axis do not satisfy the above formulas (1) and (2). When the polarizing plates 105 to 107 of the comparative example are mounted on a liquid crystal display device or an organic EL display device, the device is deformed, and the visibility of the display screen is low. This is because the polarizing plate of the comparative example is physically deformed due to being in a high-humidity environment, and the liquid crystal display device or the organic EL display device is also deformed.

The angle between the slow axis of the first optical film and the absorption axis of the polarizer is not in the range of 30 to 60°, and the polarizing plates 108 and 113 of the comparative example are in the range of 30 to 60°. The result shows that the recognition of the picture is low.

[Example 2] "Production of Polarizing Plates 201~205"

In the production of the polarizing plate 101 in the first embodiment, the polarizing plates 201 to 205 were produced in the same manner except for the method of the lateral stretching step and the oblique stretching step in the production of the first optical film.

Further, in Table 2, in the lateral stretching step, the film obtained in the casting step was dried, and the residual solvent amount was 10% by mass, and then, under the conditions of 170 ° C, the original width in the width direction was extended at 1.15 times. In the case of the elongation, the film obtained by the casting step is dried, and the amount of the residual solvent is 10% by mass. Then, at 150 ° C, the original width in the width direction is extended at a stretching ratio of 1.10 times. In the case of "Method A2", the film obtained by the casting step was dried, and the amount of residual solvent was 20% by mass. Then, at 135 ° C, the original width in the width direction was extended at a stretching ratio of 1.07 times. In the case of "Method A3", the film obtained by the casting step was dried, and the amount of residual solvent was 1% by mass, and then extended at a stretching ratio of 1.05 times with respect to the original width in the width direction at 130 °C. The case where the horizontal stretching step itself is not performed is indicated by "method A4", and is indicated by "none".

Further, in Table 2, in the oblique stretching step, the film was stretched obliquely at an extension temperature of 185 ° C and a stretching ratio of 1.7 times, and the film was stretched at a temperature of 175 ° C and a stretching ratio of 1.8 times. The case where the film is obliquely extended is "method B2".

"Evaluation of Polarizing Plates 201~205"

In the polarizing plates 201 to 205 produced as described above, the dimensional change rate before and after the heat treatment step of the first optical film, the optical value of the first optical film, and the deformation of the device mounted on the liquid crystal display device are the same as in the first embodiment. The visibility of the screen, the distortion of the device mounted in the case of the organic EL display device, and the visibility of the screen were evaluated. Further, the polarizing plates 201 to 205 which were produced were also evaluated for the yield of the polarizing plate as described below. The evaluation results are shown in Table 2. Further, in Table 2, the evaluation results of the polarizing plate 101 in the above-described first embodiment are shown.

(Polarizer yield)

The surfaces of the polarizing plates 101 and 201 to 205 which were produced were visually observed, and those having no surface failure or planar failure were good. The ratio of the good product and the defective product when 50 sheets of the polarizing plate were produced was calculated and evaluated based on the following criteria.

◎: The polarizing plate of good products is over 95%

○: The polarizing plate of the good product is 80% or more and less than 95%.

△: The polarizing plate of the good product is 60% or more and less than 80%.

×: The polarizing plate of the good product is less than 60%

As shown in Table 2, the dimensional change ratio L (MD) in the longitudinal direction of the first optical film and the dimensional change ratio L (TD) in the width direction are obtained, and the polarizing plates 101 and 202 of the present invention satisfying the above formula (3) are obtained. The polarizing plates of 203 and 205 are excellent in yield.

Further, when the first optical film is produced in order to obtain such polarizing plates 101, 202, 203, and 205, it is preferable to carry out the lateral stretching step, and the residual solvent amount is 10 to 20% by mass, and the stretching temperature is 135 to 170. Under the condition of °C and stretching ratio of 1.07~1.15 times, the lateral stretching step is better, and the lateral stretching step is better under the conditions of residual solvent amount of 10% by mass, elongation temperature of 150-170 ° C, and stretching ratio of 1.1 to 1.15. .

Further, it was found that, in the oblique stretching step in the case of producing the first optical film, when the stretching was performed under the conditions of an extension temperature of 175 ° C and a stretching ratio of 1.8 times, the stretching temperature was 185 ° C and the stretching ratio was 1.7 times. When the polarizing plate is mounted on the liquid crystal display device, it is possible to suppress the occurrence of deformation of the device and to improve the visibility of the display screen.

[Example 3] "Production of Polarizing Plates 301~306"

In the production of the polarizing plate 201 in the second embodiment, the polarizing plates 301 to 306 were produced in the same manner except that the substrate type of the first optical film was changed to that shown in Table 3.

Further, in Table 3, cellulose acetate propionate (acetamyl substitution degree 1.50, propyl ketone substitution degree 0.90, total substitution degree 2.40, weight flat The average molecular weight of 220,000) is represented by "CAP". Cellulose acetate (the degree of substitution of ethyl ketone 2.85, weight average molecular weight of 250,000) is represented by "TAC", and the cellulose acetate (acetylation degree of ethyl ketone) is 2.43, weight. The average molecular weight is 200,000.) It is represented by "DAC", cellulose acetate benzoate (acetate substitution degree 1.90, benzylidene substitution degree 0.30, total substitution degree 2.20, weight average molecular weight 150,000) to "CeBz Methylcellulose (methyl ether substitution degree 2.5, weight average molecular weight 150,000) is represented by "CE-1", and ethyl cellulose (ethyl ether substitution degree 2.5, weight average molecular weight 150,000) is "CE". -2" indicates that cellulose ether benzoate (ethyl ether substitution degree 2.2, benzylidene group substitution degree 0.7, weight average molecular weight 150,000) is represented by "CEBz".

"Evaluation of Polaroid Plates 301~306"

In the polarizing plates 301 to 306 produced as described above, the dimensional change rate before and after the heat treatment step of the first optical film, the optical value of the first optical film, and the deformation of the device mounted on the liquid crystal display device are the same as in the first embodiment. The visibility of the screen, the deformation of the device mounted in the case of the organic EL display device, and the visibility of the screen were evaluated. The evaluation results are shown in Table 3. In Table 3, the evaluation results of the polarizing plate 201 in the above-described second embodiment are also shown.

As shown in Table 3, it was found that cellulose acetate propionate or cellulose acetate benzoate was used as the material of the first optical film, and it is preferable from the viewpoint of suppressing physical deformation of the polarizing plate.

When methylcellulose is used as the material of the first optical film, the dimensional change rate L(θ) in the slow axis direction does not satisfy the above formula (2). Therefore, in the present invention, the material of the first optical film cannot be methylcellulose. Prime.

[Example 4] "Production of polarizing plates 401, 402"

In the production of the polarizing plate 101 in the first embodiment, the polarizing plates 401 and 402 were produced in the same manner except that the substrate type of the second optical film was changed to that described in Table 4.

Further, in Table 4, cellulose acetate (the degree of substitution of ethyl ketone group of 2.85 and the weight average molecular weight of 250,000) is represented by "TAC", and cellulose acetate (degree of substitution of ethyl ketone group of 2.43 and weight average molecular weight of 200,000). Expressed as "DAC".

"Evaluation of polarizing plates 401, 402"

In the same manner as in the first embodiment, the polarizing plates 401 and 402 produced as described above were evaluated for the deformation of the device and the visibility of the screen when mounted on the liquid crystal display device. The evaluation results are shown in Table 4. Further, in Table 4, the evaluation results of the polarizing plate 101 in the above-described first embodiment are shown together.

As shown in Table 4, the material of the second optical film is preferably a cellulose acetate having a cellulose acetate propionate, an ethyl ketone substitution degree of 2.43 or 2.85, more preferably a cellulose acetate. Cellulose acetate having a propionate or ethane group substitution degree of 2.43, preferably cellulose acetate propionate.

[Industrial Applicability]

As described above, the present invention is suitable for providing a polarizing plate including an optical film which is obliquely extended, a polarizing plate which suppresses the occurrence of physical deformation, a method of manufacturing the polarizing plate, and a liquid crystal display device including the polarizing plate. Electroluminescent display device.

10‧‧‧Liquid crystal display device

11‧‧‧Liquid cell

12, 13‧‧‧ polarizing plate

14‧‧‧ Backlight

15‧‧‧ front panel

21, 31‧‧‧ polarizer

22‧‧‧1st optical film

23‧‧‧ functional layer

24‧‧‧2nd optical film

32, 33‧‧‧ Optical film

Claims (12)

A polarizing plate comprising a polarizing mirror, a first optical film facing one of the polarizing mirrors, and a polarizing plate of a second optical film facing the other of the polarizing mirrors, the first optical The angle between the slow axis of the film and the absorption axis of the polarizer is 30 to 60°, and the dimensional change rate L(θ) of the slow axis direction of the first optical film is orthogonal to the slow axis. The dimensional change rate L (θ + 90) of the direction is adjusted to satisfy the following formulas (1) and (2): Formula (1): 0.50 ≦ L (θ) / L (θ + 90) ≦ 0.95 Formula (2) : 0.1 (%) ≦ L (θ) ≦ 1.5 (%). The polarizing plate of the first aspect of the invention, wherein the dimensional change ratio L (MD) in the longitudinal direction of the first optical film and the dimensional change ratio L (TD) in the width direction satisfy the following formula (3), 3): 0.50 ≦ L (MD) / L (TD) < 1.00. The polarizing plate of claim 1, wherein the first optical film contains a polymer having a cellulose skeleton. The polarizing plate of claim 1, wherein the first optical film has a retardation value Ro (550) in the in-plane direction of a wavelength of 550 nm of 75 to 150 nm. The polarizing plate of claim 1, wherein the first optical film contains cellulose acetate propionate. The polarizing plate of claim 1, wherein the slow axis of the second optical film is parallel or orthogonal to the absorption axis of the polarizer. The polarizing plate of claim 1, wherein the second optical film contains cellulose acetate or cellulose acetate propionate. The polarizing plate of the first aspect of the invention, wherein the first optical film and the second optical film are disposed on a side of the identification side of the optical film on the identification side, and a hardened layer or an anti-glare layer is provided. A method of producing a polarizing plate according to any one of claims 1 to 8, wherein the polarizing plate, the first optical film, and the second optical film are provided. A lamination step that is applied in a roll-to-roll manner. The method for producing a polarizing plate according to claim 9, further comprising the steps of: casting a dope onto the support to form a casting step of the cast film, and the residual solvent amount is 1-20 a step of extending the casting film in the width direction at a stretching ratio of 1.01 to 1.3 times in the width direction, and a step of extending the casting film in the oblique direction with respect to the width direction, The casting film is subjected to a heat treatment of the following (i) or (ii) to obtain a heat treatment step of the first optical film, and after the heat treatment step, the bonding step is performed, and (i) the casting is performed. The end portion of the film is embossed in the range of 180 to 220 ° C, and then heat-treated for 3 to 5 days under conditions of 60 to 80 ° C and 20% RH in a state of being wound into a roll. (ii) The cast film is conveyed by a transfer roller at a tension of 120 to 150 N, and the cast film is heat-treated at 140 to 170 ° C for 40 to 600 seconds via the transfer roller. A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 8. An organic electroluminescence display device comprising the polarizing plate according to any one of claims 1 to 8.