KR102027692B1 - Optical film, polarizing plate, display device, and method of manufacturing optical film - Google Patents

Abstract

The optical film is a film in which the slow axis is inclined by 10 to 80 ° with respect to one side of the film appearance in the film plane. When the optical film have been referred to as the fast axis direction and the rate of dimensional change of the slow axis direction in the before and after left to stand at 90 ℃ 120 hours, respectively ΔD _F (%) and ΔD _L (%), the optical film is, the one side in the central portion and the both end portions in the direction along a 0% ≤ΔD _F <0.5% and _L ΔD <0% satisfied, and the amount of residual solvent to less than 60ppm.

Description

Optical film, polarizing plate, display device, and manufacturing method of optical film {OPTICAL FILM, POLARIZING PLATE, DISPLAY DEVICE, AND METHOD OF MANUFACTURING OPTICAL FILM}

This invention relates to the optical film as a diagonal stretched film, the polarizing plate provided with this optical film, the display apparatus provided with this polarizing plate, and the manufacturing method of the said optical film.

Conventionally, the method of extending | stretching a resin film in the diagonal direction with respect to the width direction, and manufacturing a diagonal stretched film is proposed variously. For example, in patent document 1, a resin film is unwound from the direction different from the winding direction of the film after extending | stretching, both ends of the said resin film are gripped by a pair of holding | gripping tools, and are conveyed. And the resin film is extended to a diagonal direction by changing the conveyance direction of a resin film on the way. Thereby, the diagonal stretched film which has a slow axis in the desired angle of more than 0 degrees and less than 90 degrees with respect to a longitudinal direction or the width direction is manufactured.

The diagonally stretched film produced in this way is applicable to the circularly-polarizing plate for external light reflection prevention, for example in an organic electroluminescent (EL) display apparatus. The circular polarizing plate may be a polarizer and an inclined stretched film, for example, such that the slow axis of the inclined stretched film crosses at a desired angle (for example, 45 °) within the film plane with respect to the absorption axis (or transmission axis) of the polarizer. It is obtained by joining by a roll-to-roll system. By manufacturing a circularly polarizing plate by a roll-to-roll method, productivity of a circularly polarizing plate improves remarkably compared with the batch type which manufactures one circularly polarizing plate by bonding one diagonally stretched film and a polarizer of a predetermined | prescribed magnitude | size.

Japanese Patent Laid-Open No. 2010-173261 (see claims 1, 1, etc.)

By the way, the solution casting film forming method and the melt casting film forming method are known as a typical manufacturing method which manufactures the resin film (long film) used as the basis of a diagonal stretched film. In the solution casting film forming method, a dope in which a resin and an additive is dissolved in a solvent is cast and dried on a metal support to release a casting film (web) from the metal support, followed by stretching or width of the casting film, and then drying the casting film. How to get a film. On the other hand, the melt casting film forming method is a method in which a resin composition containing a resin and an additive is heated and melted to a temperature showing fluidity, and thereafter, the melt having fluidity is cast to obtain a resin film.

When the resin film film-formed by the solution casting film forming method is obliquely stretched, and the obtained diagonal stretched film is adhere | attached with a polarizer and a polarizing plate is produced, under high temperature environment at the time of adhesion (for example, when UV cure adhesive is used, high temperature by ultraviolet irradiation) At the time of heating in order to accelerate the curing of the environment, or in the case of heating to promote curing when water-based adhesives such as water glue are used), the inclined stretched film is perpendicular to the slow axis direction in the slow axis direction and the fast axis direction in the film plane. Direction) in both directions. For this reason, the inventors of the present application conjecture as follows.

The resin film formed into a film by the solution casting film forming method has a low density of resin compared with the resin film formed into a film by the melt casting film forming method. This is because, in the solution casting film forming method, a gap (space after the solvent has evaporated out) is generated in the film by evaporation of the solvent contained in the casting film by drying of the casting film after stretching. As described above, the film having a low resin density tends to extend in the stretching direction (inclined direction (ground axis direction) relative to the width direction) at the time of oblique stretching, and furthermore, due to the effect of tension acting and stretching in the conveying direction. It becomes easy to extend also in a direction. Therefore, after the film is diagonally stretched, tensile stress remains in both directions in the slow axis direction and the fast axis direction. In the high temperature environment, since the tensile stress is relaxed, the film shrinks in both directions in the slow axis direction and the fast axis direction.

Thus, in a high temperature environment, when the diagonal stretched film shrinks in both directions in the slow axis direction and the fast axis direction, the whole film causes a dimensional change and shrinks. As a result, curl generate | occur | produces in the polarizing plate which bonded the polarizer and the diagonally stretched film, or the adhesiveness of a polarizer and the diagonally stretched film falls, and a diagonally stretched film will peel easily. As a result, in the organic EL display device to which the polarizing plate is applied, light leakage due to external light reflection occurs during black display.

Moreover, even when the resin film formed into a film by the melt casting film method is diagonally stretched, and the obtained diagonal stretched film is adhere | attached with a polarizer and a polarizing plate is produced, depending on the extending | stretching condition at the time of diagonal stretch, after a diagonal stretch, the slow-axis direction and The tensile stress remains in both directions in the fast axis direction, and under the high temperature environment at the time of bonding, the inclined stretched film shrinks in both directions in the slow axis direction and the fast axis direction, resulting in a dimensional change. We have learned from various reviews.

On the other hand, in the liquid crystal display device, a circular polarizing plate is arranged on the viewing side with respect to the liquid crystal layer in order to enable the observer to observe the display image even when the viewer wears polarized sunglasses and is in a straight state or tilts the head sideways. There is also. In such a configuration, when curl occurs on the circularly polarizing plate due to the dimensional change of the inclined stretched film under a high temperature environment, distortion occurs in the image visually recognized through the circularly polarizing plate, and the visibility of the display image is lowered.

Therefore, in order to suppress the light leakage by the external light reflection in an organic electroluminescent display, and the fall of the visibility of the display image in the liquid crystal display device corresponding to polarized sunglasses, it inclines under the high temperature environment at the time of sticking a diagonal stretched film to a polarizer. It is necessary to suppress the dimensional change of the whole stretched film. However, such a diagonal stretched film is not yet proposed.

This invention is made | formed in order to solve the said problem, The objective is the optical film as a diagonal stretched film which can suppress the dimensional change in high temperature environment, the polarizing plate containing this optical film, and the polarizing plate containing It is to provide a display device.

The said object of this invention is achieved by the following structures.

1. An optical film in which the slow axis is inclined by 10 to 80 ° with respect to one side of the film appearance within the film plane,

When the optical film have been referred to as the fast axis direction and the rate of dimensional change of the slow axis direction in the before and after left to stand at 90 ℃ 120 hours, respectively ΔD _F (%) and ΔD _L (%), the central portion of the along the one side direction, And at both ends,

0% ≤ΔD _F <0.5%

ΔD _L <0%

Satisfy

The amount of residual solvent is 60 ppm or less, The optical film characterized by the above-mentioned.

2. The amount of residual solvent is 10 ppm or less, The said optical film of 1 characterized by the above-mentioned.

3. In the said optical film, as distance between two points arrange | positioned in a fast axis direction, the distance before leaving this optical film for 120 hours at 120 degreeC, and after leaving is respectively a1 (mm) and a2 (mm), respectively. and,

In the said optical film, as distance between two points arrange | positioned in a slow axis direction, when the optical film is left to stand at 90 degreeC for 120 hours, and the distance after leaving it is set to b1 (mm) and b2 (mm), respectively. ,

ΔD _F = {(a2-a1) / a1} × 100

ΔD _L = {(b2-b1) / b1} × 100

It is an optical film as described in said 1 or 2 characterized by the above-mentioned.

4. In the center part of the direction along one said side, the rate of dimensional change in the fast-axis direction before and after leaving this optical film to stand at 90 degreeC for 120 hours is called (DELTA) D _FC (%),

In one end of the direction along the said one side, the rate of dimensional change in the fast-axis direction before and after leaving this optical film at 120 degreeC for 120 hours is called (DELTA) D _F-E1 (%),

In the other end part of the direction along the said one side, when the dimension change rate of the up-axis direction before and after leaving this optical film to stand at 90 degreeC for 120 hours is set to (DELTA) D _F-E2 (%),

(ΔD _{F -E1} + ΔD _{F -E2} ) / 2> ΔD _{F -C}

It is further satisfied, The optical film in any one of said 1-3 characterized by the above-mentioned.

5. The optical film is a long shape,

The direction along one said side is the width direction perpendicular | vertical to the longitudinal direction in the film surface of the said optical film, The optical film in any one of said 1-4 characterized by the above-mentioned.

6. It contains the optical film as described in any one of said 1-5, and a polarizer,

The said optical film is located in the one side with respect to the said polarizer so that a slow axis may intersect the absorption axis of the said polarizer in a film plane.

7. It contains polarizing plate of 6, and display cell,

The polarizing plate is located on the viewing side with respect to the display cell.

8. The said optical film of the said polarizing plate is located in the said display cell side with respect to the said polarizer, The display apparatus of said 7 characterized by the above-mentioned.

9. Said display cell is organic electroluminescent element, The display apparatus of said 8 characterized by the above-mentioned.

10. The said optical film of the said polarizing plate is located in the opposite side to the said display cell with respect to the said polarizer, The display apparatus of said 7 characterized by the above-mentioned.

11. Said display cell is liquid crystal cell, Said display apparatus of 10 characterized by the above-mentioned.

12. As a manufacturing method of the optical film in any one of said 1-5.

The long film is conveyed by holding both ends in the width direction of the long film with a pair of grippers, leading one gripper relative to the other gripper, and bending and conveying the long film in the film plane. Extending | stretching to the diagonal direction with respect to, and obtaining the diagonal stretched film which comprises the said optical film, Comprising:

In each end part of the width direction of the said elongate film, the force applied to a conveyance direction by each holding | gripping tool is called same Tr (N), respectively, before diagonal stretch,

During the diagonal stretching, at each end of the elongated film in the width direction, the force exerted on the conveying direction by the gripper on the relatively retarding side and the gripper on the relatively preceding side is respectively applied to To (N) and Ti. When we say (N),

In the oblique stretching step,

(Ti-Tr) /Tr≥1.7

(Tr-To) /Tr≥1.5

The long film is stretched in the oblique direction so as to satisfy the manufacturing method of the optical film.

13. In the said diagonal stretch process, the edge part gripped by the holding | gripping tool of a side which is relatively delayed among each edge part of the width direction of the said long film is cooled, The manufacturing method of the said 12 optical film characterized by the above-mentioned.

14. At the said diagonal stretch process, the said elongate film is diagonally stretched so that the slow axis may orientate at an orientation angle larger than a desired orientation angle with respect to the width direction of the said long film, and the said slow axis is then made into the said desired orientation angle. The said elongate film is diagonally stretched so that it may orientate, The manufacturing method of the optical film as described in said 12 or 13 characterized by the above-mentioned.

An optical film is what is called a diagonal stretched film in which the slow axis was inclined 10-80 degrees with respect to one side of a film external appearance in a film plane. In the center part and both ends of the direction along the said one side of this optical film, the rate of change of dimensions ΔD _{F in the} fast axis direction and the slow axis direction By satisfying the above conditional expression with respect to ΔD _L , the optical film expands in the fast axis direction in the high temperature environment or shrinks in the slow axis direction without changing the dimensions. Thus, since an optical film does not shrink | contract in a fast axis direction in high temperature environment, even if there exists shrinkage of a slow axis direction in high temperature environment, dimensional change (shrinkage) as a whole film can be suppressed.

Thereby, even when a polarizer and an optical film are adhere | attached at high temperature and a polarizing plate is produced, it can suppress that curl generate | occur | produces in a polarizing plate and the adhesiveness of an optical film with respect to a polarizer falls due to the dimension change of an optical film. . As a result, in the organic electroluminescence display to which the said polarizing plate is applied, generation | occurrence | production of light leakage by external light reflection at the time of black display can be suppressed. Moreover, in the liquid crystal display device corresponding to the polarizing sunglasses which applied the said polarizing plate, it can suppress that distortion generate | occur | produces in the image visually recognized through the said polarizing plate, and can suppress the fall of the visibility of a display image.

1: is explanatory drawing which shows schematic structure of the manufacturing apparatus of the diagonal stretched film which concerns on embodiment of this invention typically.
It is a top view which shows typically an example of the rail pattern of the extending | stretching part with which the said manufacturing apparatus is equipped.
3 is a plan view showing the details of the configuration of the stretching section.
4 is an exploded perspective view showing a schematic configuration of a polarizing plate.
5 is a cross-sectional view illustrating the structure of an outline of an organic EL display device.
6 is a cross-sectional view illustrating a schematic configuration of a liquid crystal display device.
It is explanatory drawing which shows typically the behavior in the width center part and width edge part of the adhesive agent and optical film at the time of adhesive hardening.
It is explanatory drawing which shows typically the force of the conveyance direction applied to the both ends of the width direction of a long film in the said extending part.
9 is an explanatory diagram schematically showing another configuration of the stretching section.
FIG. 10: is explanatory drawing which shows another structure of the said extending part typically.

EMBODIMENT OF THE INVENTION When one Embodiment of this invention is described based on drawing, it is as follows. In addition, in this specification, when numerical range is described as A-B, the value of the lower limit A and the upper limit B is included in the numerical range. In addition, this invention is not limited to the following content.

The diagonally stretched film which concerns on this embodiment is an elongate diagonal stretched film which has an in-plane slow axis at arbitrary angles with respect to the width direction of the film after extending | stretching by diagonally stretching an elongate resin film, or its long shape inclination It is a sheet-like diagonal stretched film obtained by cut | disconnecting a stretched film along the width direction.

Here, a long thing refers to the length of about 5 times or more with respect to the width of a film, Preferably it points to 10 times or more length, Specifically, a film is wound in roll shape and stored in the state of a film roll, or Indicates the length of conveyance. In the elongate film manufacturing method, a film can be manufactured to arbitrary arbitrary length by manufacturing a film continuously. In addition, in the manufacturing method of an elongate diagonal stretched film, after forming a elongate film into a film, this is wound up to a winding core once to make a winding object (long film raw material), and the elongate film is diagonally stretched from this winding object. It may be supplied to a diagonal stretched film, and you may supply to a diagonal stretch process continuously from a film forming process, and may manufacture a diagonal stretched film, without winding up the elongate film after film forming. It is preferable to carry out a film forming process and a diagonal stretch process continuously because it can feed back the result of the film thickness and optical value after extending | stretching, change film forming conditions, and obtain the desired elongate diagonal stretched film.

In the manufacturing method of the diagonal stretched film which concerns on this embodiment, the elongate inclination which has a slow axis in the angle (for example, the angle of 10-80 degree with respect to the width direction) more than 0 degree with respect to the width direction of a film. A stretched film is produced. Here, an angle with respect to the width direction of a film is an angle in a film plane. Since the slow axis is usually expressed in a direction perpendicular to the stretching direction or the stretching direction, in the manufacturing method according to the present embodiment, the slow axis has such a slow axis by stretching at an angle of more than 0 ° and less than 90 ° with respect to the width direction of the film. An elongate diagonal stretched film can be produced. The angle | corner of the width direction of a elongate diagonal stretched film and a slow axis, ie, an orientation angle, can be arbitrarily set to a desired angle in the range more than 0 degree and less than 90 degree. In addition, in this embodiment, when it describes as "a long film," it shall refer to the elongate resin film before diagonal stretch.

<About long film>

First, the long film used as extending object in this embodiment is demonstrated.

The long film of the present embodiment is not particularly limited, and any film may be used as long as it is a film composed of a thermoplastic resin. For example, when the film after stretching is used for optical purposes, the resin has a transparent property with respect to a desired wavelength. The film containing is preferable. As such resin, polycarbonate resin (PC), polyester resin, olefin polymer resin (cycloolefin resin, COP) which has alicyclic structure, polyether sulfone resin, polyethylene terephthalate resin, poly Mid type resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polyvinyl chloride resin, etc. are mentioned.

Polycarbonate resin is a polyester of carbonic acid and glycol or dihydric phenol, a polymer having a carbonate bond of -O-CO-O-, and the polymer of bisphenol and carbonate is most practically used. , Teijin Corporation (Panlite (registered trademark), Pure Ace (registered trademark)), Kawasaki Corporation Kaneka (Elmac (registered trademark)), Mitsubishi Engineering Plastics Corporation (Yupiron (registered trademark)), etc. It is commercially available. Of course, a polymer copolymerized with a monomer having a fluorene group (see, for example, Japanese Patent Application Laid-Open No. 2005-189632) exhibits reverse wavelength dispersion of retardation, so such polycarbonates may also be enjoyed depending on the application. Can be used.

Examples of the polyester resin include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and the like, and polymers copolymerized with monomers having a fluorene group show reverse wavelength dispersion of phase difference. Polyester can also be used conveniently according to a use.

As polyethylene naphthalate type resin, the polyethylene naphthalate manufactured by polycondensing lower alkyl ester of naphthalenedicarboxylic acid and ethylene glycol can be used suitably, for example. As a commercial item, Theonex (made by Teijin Corporation) etc. can be used suitably.

It will not specifically limit, if it is resin which has a unit of the monomer containing cyclic olefin (cycloolefin) as cycloolefin resin. The cycloolefin resin may be either a cycloolefin polymer (COP) or a cycloolefin copolymer (COC). A cycloolefin copolymer means amorphous cyclic olefin resin which is a copolymer of cyclic olefin and olefins, such as ethylene.

As said cyclic olefin, polycyclic cyclic olefin and monocyclic cyclic olefin exist. As such a polycyclic cyclic olefin, norbornene, methyl norbornene, dimethyl norbornene, ethyl norbornene, ethylidene norbornene, butyl norbornene, dicyclopentadiene, dihydrodicyclopentadiene, Methyldicyclopentadiene, dimethyldicyclopentadiene, tetracyclododecene, methyltetracyclododecene, dimethylcyclotetradodecene, tricyclopentadiene, tetracyclopentadiene and the like. Examples of the monocyclic cyclic olefins include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctatriene, and cyclododecatene.

Cycloolefin resin can also be obtained as a commercial item, For example, Nippon Zeon company "ZEONOR", JSR company "ARTON", polyplastics company "TOPAS", Mitsui Chemicals Corporation "APEL", etc. are mentioned, for example. .

In addition, as resin which comprises a long film, the resin composition of Unexamined-Japanese-Patent No. 2006-45369, and the alkoxy cinnamic acid ester type polymer of Unexamined-Japanese-Patent No. 2016-108544 can also be used.

<Film forming method of long film>

As a film forming method of a long film, there exist a solution casting film forming method and a melt casting film forming method shown below. Hereinafter, each film forming method will be described. In addition, in this embodiment, in order to acquire the characteristic that the film after diagonal stretch does not shrink | contract in the fast-axis direction under high temperature environment, the long film used as the object of diagonal stretch is formed into a film by the melt casting film forming method. .

[Solution flexible film forming method]

In the solution casting film forming method, a process of preparing a dope by dissolving a resin and an additive in a solvent, a step of casting the dope on a belt or drum-shaped metal support, a step of drying the flexible dope as a casting film (web), and a metal support The process of peeling a web, the process of extending | stretching or width maintaining a web, the process of drying a web, and the process of winding up the finished film are performed.

As for the metal support body of a casting | flow_spread process, it is preferable that the surface was mirror-finished, and the drum which plated the surface with the stainless steel belt or the casting is used preferably. The surface temperature of a metal support body is set to -50 degreeC-below the temperature at which a solvent boils and does not foam. The higher the support temperature, the faster the drying speed of the web is preferable, but if it is too high, the web may foam or the planarity may deteriorate.

As preferable support body temperature, it determines suitably at 0-100 degreeC, and 5-30 degreeC is more preferable. Or it is also a preferable method to gelatinize a web by cooling and peeling from a drum in the state containing many residual solvents. Although the method of controlling the temperature of a metal support body is not specifically limited, There exists a method of blowing a warm air or cold wind, or the method of making hot water contact the back side of a metal support body. The use of warm water is preferable because heat is efficiently transferred and the time until the temperature of the metal support becomes constant is short.

When using warm air, the wind of temperature higher than the target temperature may be used, considering the temperature fall of the web by the latent heat of evaporation of a solvent, using the warm air more than the boiling point of a solvent, and preventing foaming.

It is preferable to change the temperature of a support body and the temperature of a drying wind until it peels from casting | flow_spread especially, and to dry efficiently.

In order for the resin film formed into a film to show favorable planarity, it is preferable that the amount of residual solvent at the time of peeling a web from a metal support body is a desired range. Here, the residual solvent amount is defined by the following formula.

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

In addition, M is the mass (g) of the sample extract | collected at the arbitrary time after manufacture of a web or a film, and N is the mass (g) after heating M at 115 degreeC for 1 hour.

In the film drying process, the method of drying while conveying a web is generally employ | adopted by the roll drying method (the method of passing a web through several rolls arrange | positioned up and down alternately), and a tenter system.

[Melt casting film forming method]

The melt casting film forming method is a method of heating and melting a resin composition containing additives such as a resin and a plasticizer to a temperature exhibiting fluidity, and then casting a melt having fluidity to form a film. The method formed by melt casting can be classified into a melt extrusion method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method and the like. Among these, the melt extrusion method in which the film excellent in mechanical strength, surface precision, etc. is obtained is preferable. In addition, it is preferable to knead | mix and pelletize several raw materials normally used by the melt-extrusion method previously.

Pelletization may be performed by a well-known method. For example, dry resins, plasticizers, and other additives can be fed into an extruder by a feeder, kneaded using a single or twin screw extruder, extruded into a strand shape from a die, cooled by water or air cooled, and pelletized by cutting. .

The additives may be mixed with the resin before being fed to the extruder, or the additive and the resin may be fed to the extruder in separate feeders. In addition, in order to mix uniformly a small amount of additives, such as particle | grains and antioxidant, it is preferable to mix in resin beforehand.

The extruder is capable of pelletizing so that the shearing force is suppressed and the resin does not deteriorate (molecular weight decrease, coloring, gel formation, etc.) and is preferably processed at a low temperature as possible. For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a screw of a deep groove type. In view of the uniformity of kneading, the engagement type is preferred.

Film film forming is performed using the pellet obtained by making it above. Of course, it is also possible to supply powder of a raw material to an extruder with a feeder as it is, without pelletizing, and to film-film as it is.

After the pellets are extruded using a single screw or twin screw extruder, the melt temperature at the time of extruding is set to about 200 to 300 ° C., and the foreign matter is removed by filtration with a filter of a leaf disc type, and then cast into a film form from a T die. Then, the film is nip with the cooling roll and the elastic touch roll, and the film is solidified on the cooling roll.

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

The extrusion flow rate is preferably performed stably by introducing a gear pump. Moreover, as for the filter used for removal of a foreign material, a stainless fiber sintering filter is used preferably. The stainless steel fiber sintered filter is a product in which a stainless fiber body is intricately entangled, compressed, and then sintered and integrated into contact points. The density can be changed by the thickness and the amount of compression of the fiber, and the filtration precision can be adjusted. .

Additives, such as a plasticizer and particle | grains, may be previously mixed with resin, and may be kneaded in the middle of an extruder. In order to add uniformly, it is preferable to use mixing apparatuses, such as a static mixer.

It is preferable that the film temperature on the touch roll side at the time of nipping a film with a cooling roll and an elastic touch roll shall be Tg (glass transition temperature) or more and Tg + 110 degrees C or less of a film. A well-known roll can be used for the roll which has an elastic body surface used for such an objective.

An elastic touch roll is also called pinching rotary body. A commercially available thing can also be used as an elastic touch roll.

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

In addition, the long film formed by each said film forming method may be a single | mono layer, or a laminated film of two or more layers. Laminated | multilayer film can be obtained by well-known methods, such as a co-extrusion shaping | molding method, a co-compression molding method, a film lamination method, and a coating method. Of these, the coextrusion molding method and the co-lead molding method are preferable.

<Specification of the long film>

The thickness of the long film in this embodiment becomes like this. Preferably it is 30-300 micrometers, More preferably, it is 40-150 micrometers. In addition, in this embodiment, thickness nonuniformity (sigma) m of the flow direction (conveying direction) of the long film supplied to the stretching zone mentioned later maintains the take-up tension of the film in the diagonal stretch tenter entrance mentioned later, and maintains an orientation angle and From the standpoint of stabilizing optical properties such as retardation, it is preferably less than 0.30 μm, preferably less than 0.25 μm, more preferably less than 0.20 μm. When thickness nonuniformity (sigma) m in the flow direction of a long film becomes 0.30 micrometer or more, the fluctuation | variation of optical characteristics, such as retardation and an orientation angle of a long stretched film, may deteriorate.

Moreover, the film which has a thickness gradient of the width direction may be supplied as a long film. The gradient of the thickness of a long film can be obtained empirically by drawing the film which varied the thickness gradient experimentally so that the film thickness in the position to which the extension of the subsequent process was completed may be made the most uniform. The gradient of the thickness of a long film can be adjusted so that thickness of the edge part of the thick side may become about 0.5 to 3% thicker than the edge part of the thin thickness side, for example.

Although the width | variety of a long film is not specifically limited, 500-4000 mm, Preferably it can be 1000-2000 mm.

Preferable elastic modulus at the extending | stretching temperature at the time of diagonal stretch of a long film is represented by a Young's modulus, and is 0.01 MPa or more and 5000 MPa or less, More preferably, it is 0.1 MPa or more and 500 MPa or less. If the elastic modulus is too low, the shrinkage ratio at the time of stretching and after stretching is lowered, and wrinkles are less likely to disappear. In addition, when the elastic modulus is too high, the tension applied at the time of stretching becomes large, it is necessary to increase the strength of the portion holding both side edges of the film, and the load on the tenter of the subsequent step becomes large.

As a long film, an unoriented thing may be used and the film which has orientation in advance may be supplied. Moreover, if necessary, distribution of the width direction of the orientation of an elongate film may have comprised arch shape, what is called boeing. In other words, the orientation state of the long film can be adjusted so that the orientation of the film at the position where the stretching of the subsequent step is completed can be made desired.

<The manufacturing method and manufacturing apparatus of a long diagonal stretched film>

Next, the manufacturing method and manufacturing apparatus of the diagonal stretched film which extend | stretch the above-mentioned elongate film in the diagonal direction with respect to the width direction, and manufacture the elongate diagonal stretched film are demonstrated.

(Overview of the device)

FIG. 1: is explanatory drawing which shows typically the structure of the outline of the manufacturing apparatus 1 of the diagonal stretched film. The manufacturing apparatus 1 of this embodiment has the film feeding part 2, the conveying direction change part 3, the guide roll 4, and the extending | stretching part 5 in order from the conveyance direction upstream of an elongate film. ), A guide roll 6, a conveying direction change unit 7, a film cutting device 8, and a film winding unit 9. In addition, the detail of the extending | stretching part 5 is mentioned later.

The film feeding part 2 extracts the above-mentioned long film and supplies it to the extending | stretching part 5. This film feeding part 2 may be comprised separately from the film forming apparatus of a long film, and may be comprised integrally. In the former case, a long film is unwound from the film feeding part 2 by winding up a long film to the winding core once after film-forming, and loading the thing which became a wound body into the film feeding part 2. On the other hand, in the latter case, the film feeding part 2 is pulled out with respect to the extending | stretching part 5, without winding up the long film after film forming of a long film.

The conveyance direction change part 3 changes the conveyance direction of the elongate film pulled out from the film feeding part 2 to the direction toward the inlet of the extending | stretching part 5 as a diagonal stretch tenter. Such conveying direction change part 3 is comprised including the turn bar which changes conveyance direction by folding, for example conveying a film, and the turntable which rotates the turn bar in the plane parallel to a film.

By changing the conveyance direction of a long film in the conveyance direction change part 3 as mentioned above, it becomes possible to narrow the width | variety of the manufacturing apparatus 1 whole, and it is possible to finely control the sending position and angle of a film. It becomes possible to obtain the elongate stretched film with small deviation of a film thickness and an optical value. In addition, when the film feeding part 2 and the conveyance direction change part 3 are movable (slidable and pivotable), the left-right clip which pinches the both ends of the width direction of a long film in the extending | stretching part 5 (waves The bite defect to the film of the earth) can be effectively prevented.

In addition, the said film feeding part 2 may be made to be able to slide and rotate so that a long film can be sent out at a predetermined angle with respect to the entrance part of the extending | stretching part 5. In this case, it can be set as the structure which omitted the installation of the conveyance direction change part 3.

At least one guide roll 4 is provided in the upstream of the extending | stretching part 5, in order to stabilize the track | orbit at the time of the run of a long film. In addition, the guide roll 4 may be comprised from a pair of roll pairs which pinch | films up, and may be comprised from the some roll pair. The guide roll 4 which is closest to the inlet of the extending | stretching part 5 is a driven roll which guides the running of a film, and is axially rotatably supported by the bearing part which is not shown, respectively. As a material of the guide roll 4, a well-known thing can be used. In addition, in order to prevent the occurrence of scratches on the film, it is preferable to reduce the weight of the guide roll 4 by applying a ceramic coat to the surface of the guide roll 4 or chromium plating on a light metal such as aluminum.

Moreover, it is preferable that one of the rolls upstream than the guide roll 4 closest to the inlet of the extending | stretching part 5 presses a rubber roll and nips. By setting it as such a nip roll, it becomes possible to suppress the fluctuation | variation of the feeding tension in the flow direction of a film.

A pair of bearing portions at both ends (left and right) of the guide roll 4 closest to the inlet of the stretching portion 5 is a film tension detection device for detecting tension generated in the film in the roll. A tension detection device and a second tension detection device are provided respectively. As a film tension detection apparatus, a load cell can be used, for example. As a load cell, the well-known thing of tension or compression type can be used. A load cell is a device which converts and loads the load acting on a landing point into an electrical signal by the distortion gauge attached to the distortion body.

The load cell is provided in the left and right bearing portions of the guide roll 4 closest to the inlet of the stretching portion 5, so that the force applied to the roll by the film during travel, that is, in the film advancing direction generated in the vicinity of both side edges of the film. To detect the tension of left and right independently. Moreover, you may attach a distortion gauge directly to the support body which comprises the bearing part of a roll, and detect a load, ie, film tension, based on the distortion which generate | occur | produces in this support body. The relationship between distortion and film tension generated is measured in advance, and it is assumed to be known.

When the position and conveyance direction of the film supplied to the extending | stretching part 5 from the film feed part 2 or the conveyance direction change part 3 are shifted from the position and conveyance direction toward the inlet of the extending | stretching part 5, Depending on the amount of shift, a difference occurs in the tension in the vicinity of both side edges of the film in the guide roll 4 closest to the inlet of the stretching portion 5. Therefore, by providing the above-mentioned film tension detection apparatus and detecting the said tension difference, the grade of the said deviation can be discriminated. That is, if the conveyance position and conveyance direction of a film are appropriate (as long as it is a position and direction toward the inlet of the extending | stretching part 5), although the load which acts on the said guide roll 4 will become roughly equal at both ends of an axial direction, Otherwise, a difference occurs in the film tension from left to right.

Therefore, for example, the above-mentioned conveyance direction changing part 3 positions the film and the conveying direction (stretching part) so that the left and right film tension differences of the guide roll 4 closest to the inlet of the stretching part 5 become equal. By adjusting the angle with respect to the inlet of (5) appropriately, the holding | gripping of the film by the holding | gripping tool of the inlet part of the extending | stretching part 5 is stabilized, and the generation | occurrence | production of a malfunction, such as a gripper deviation | offset, can be reduced. Moreover, the physical property in the width direction of the film after diagonal stretch by the extending | stretching part 5 can be stabilized.

At least one guide roll 6 is provided in the downstream of the extending | stretching part 5, in order to stabilize the track | orbit at the time of the running of the film (long-shaped obliquely stretching film) diagonally stretched by the extending | stretching part 5. .

The conveyance direction change part 7 changes the film conveyance direction after extending | stretching conveyed from the extending | stretching part 5 to the direction toward the film winding part 9. The conveyance direction change part 7 can be comprised by the folding mechanism which folds the film after extending | stretching at least once along the direction parallel or perpendicular | vertical in the extending direction in the surface of an elongate diagonal stretched film, for example.

Here, in order to cope with the fine adjustment of an orientation angle (direction of the in-plane slow axis of a film), and product variation, the film advancing direction in the inlet of the extending | stretching part 5, and the film advancing direction in the exit of the extending | stretching part 5 are It is necessary to adjust the angle to be achieved.

Moreover, it is preferable to perform film forming and diagonal stretch continuously in terms of productivity or a yield. When performing a film forming process, a diagonal stretch process, and a winding process continuously, the advancing direction of a film is changed by the conveyance direction change part 3 and / or conveyance direction change part 7, and the film | membrane process and the winding process of a film are carried out. 1, that is, as shown in FIG. 1, the advancing direction (feeding direction) of the film pulled out from the film feeding part 2, and the film advancing direction immediately before winding up by the film winding part 9 By making (winding direction) match, the width | variety of the whole apparatus with respect to a film advancing direction can be made small.

In addition, although the advancing direction of a film does not necessarily need to match in a film forming process and a winding process, the conveyance direction change part 3 and / or so that it may become a layout which does not interfere with the film feeding part 2 and the film winding part 9. Or it is preferable to change the advancing direction of a film by the conveyance direction change part 7.

As said conveyance direction change part 3 * 7, it can implement | achieve by a well-known method, such as using an air flow roll.

The film cutting device 8 cuts the film (long diagonal stretched film) extended | stretched by the extending | stretching part 5 along the width direction in the part of predetermined | prescribed film length (winding length), and cut | disconnects the cutting member 8a. Have The cutting member 8a is composed of, for example, a scissors or a cutter (including a slitter and a strip-shaped blade (thomson blade)), but is not limited to these. In addition, a rotating round saw or a laser irradiation device It is also possible to configure such as.

The film winding | winding part 9 winds the film conveyed through the conveyance direction change part 7 from the extending | stretching part 5, For example, it consists of a winder apparatus, a mounting apparatus, a drive apparatus, etc. It is preferable that the film winding part 9 is a structure which can slide to a horizontal direction in order to adjust the winding position of a film.

The film winding-up part 9 is able to finely control the take-up position and angle of a film so that a film may be taken in with respect to the exit of the extending | stretching part 5 at a predetermined angle. Thereby, it becomes possible to obtain the elongate stretched film with small deviation of a film thickness and an optical value. Moreover, while the wrinkle generation of a film can be prevented effectively, since the winding property of a film improves, it becomes possible to wind a film long. In this embodiment, the film take-up tension T (N / m) after extending | stretching is 100N / m <T <700N / m, It is preferable to adjust between 150N / m <T <250N / m.

When the said pull-out tension is 100 N / m or less, slack and wrinkles of a film are easy to generate | occur | produce, and the profile of the width direction of the film of retardation and an orientation angle also worsens. On the contrary, when a pull-out tension becomes 700 N / m or more, the deviation of the width direction of the film of an orientation angle may become severe, and may worsen a width yield (width acquisition efficiency).

In addition, in this embodiment, it is preferable to control the fluctuation | variation of the said pull tension T with the precision of less than +/- 5%, Preferably it is less than +/- 3%. If the variation in the pulling tension T is ± 5% or more, the variation in the optical characteristics in the width direction and the flow direction (the conveying direction) is increased. As a method of controlling the fluctuation | variation of the said pulling tension T in the said range, the load applied to the first roll (guide roll 6) of the exit side of the extending | stretching part 5, ie, the tension of a film, is measured, and the value is The method of controlling the rotational speed of the take-up roll (winding roll of the film winding | winding part 9) by a general PID control system is mentioned so that it may become constant. As a method of measuring the said load, the load cell is attached to the bearing part of the guide roll 6, and the method of measuring the load applied to the guide roll 6, ie, the tension of a film, is mentioned. As a load cell, a well-known thing of a tension | pulling type | mold or a compression type can be used.

After the film is stretched, the grip by the gripper of the stretcher 5 is opened, discharged from the outlet of the stretcher 5, and both ends (both sides) of the film held by the gripper are trimmed sequentially. It is wound up by a winding core (winding roll), and turns into a winding body of an elongate diagonal stretched film. In addition, the trimming may be performed as necessary.

In addition, before winding up the elongate diagonal stretched film, you may wind up a masking film simultaneously on an elongate oblique stretched film in order to prevent the blocking of films, and among the elongate oblique stretched films which overlap by winding. You may wind up, bonding a tape etc. to the end of at least one side (preferably both). The masking film is not particularly limited as long as it can protect the elongated diagonal stretched film, and examples thereof include polyethylene terephthalate film, polyethylene film, and polypropylene film.

In addition, before winding up the elongate diagonal stretched film, the part which made the volume larger than the film surface called a knurling part or an embossing part in the width direction both ends of the at least one surface (preferably both surfaces) of this film (convex part) ) May be prevented from blocking the films when the film is wound. In addition, the height and shape of a knurling part may differ in both ends of a width direction (it may be asymmetrical).

(The details of the drawing part)

Next, the detail of the extending | stretching part 5 mentioned above is demonstrated. FIG. 2: is a top view which shows an example of the rail pattern of the extending | stretching part 5 typically. 3 is a top view which shows the detail of the structure of the extending | stretching part 5. FIG. In addition, these are examples, and this invention is not limited to these structures.

The manufacturing apparatus 1 is performed using the tenter (inclined stretching machine) which can be diagonally stretched as the extending | stretching part 5. This tenter is an apparatus which heats a long film to arbitrary temperatures which can be extended | stretched, and diagonally stretches. The tenter includes a heating zone Z, a pair of left and right rails RiRo, a plurality of grippers 15 (in FIG. 2, and conveniently, a pair of left and right grippers Ci among the plurality of grippers 15. Only Co is shown). In addition, the detail of heating zone Z is mentioned later.

The rails Ri · Ro are each configured by connecting a plurality of rail portions at the connecting portions, and are constituted as rails of an endless track (white circles in FIG. 2 are examples of the connecting portions). As shown in FIG. 3, the rail Ri of the one end side (left side) of the width direction of a film conveys the travel rail part 11 for advancing the holding | gripping tool 15 in the conveyance direction of a long film, and a long film. The return rail part 12 for advancing the holding | gripping tool 15 in the opposite direction to a direction is comprised. The rail Ro on the other end side (right side) in the width direction of the film is a row rail 13 for advancing the gripper 15 in the conveying direction of the long film and the gripper in the opposite direction to the conveying direction of the long film ( It is comprised by connecting the return rail part 14 for advancing 15).

The holding | gripping tool 15 is comprised by the clip which grips the both ends of the width direction of a film, is provided corresponding to each rail RiRo, and is equally spaced along the conveyance direction (each RiRo) of a film. Plurally installed. One end side in the width direction of the film is gripped by a plurality of grippers 15 arranged along the conveyance direction (rail Ri), and the other end side is a plurality of grippers 15 arranged along the conveyance direction (rail Ro). The film is conveyed by holding in the state, and the holding tool 15 travels along the rail Ri · Ro in this state.

The gripper 15 traveling along the left rail Ri travels along the travel rail 11 in a state in which one end of the film is held, and the gripper of the film is opened near the exit of the stretched section 5. After traveling along the return rail part 12 and returning to the vicinity of the entrance part of the extending | stretching part 5, and holding | gripping one end part of a film again, the same process as the above is repeated (circumferentially along rail Ri). On the other hand, the holding | gripping tool 15 which runs along the rail Ro on the right side runs along the running rail part 13 in the state which hold | maintained the one end part of the film, and the holding | gripping of a film is opened near the exit of the extending | stretching part 5. After that, it travels along the return rail part 14, returns to the vicinity of the entrance part of the extending | stretching part 5, and grips the other end part of a film again, and repeats a process similar to the above (wound along rail Ro box).

In FIG. 2, the conveyance direction D1 before extending | stretching a long film differs from the conveyance direction D2 after extending | stretching a long film, and has comprised feeding angle (theta) i between conveyance direction D2 after extending | stretching. Feeding angle (theta) i can be arbitrarily set to desired angle in the range exceeding 0 degrees and less than 90 degrees.

Thus, since the conveyance direction D1 before extending | stretching and the conveyance direction D2 after extending | stretching differ, the rail pattern of a tenter becomes asymmetrical shape. And rail pattern can be adjusted manually or automatically according to the orientation angle (theta), a draw ratio, etc. which are given to the elongate diagonal stretched film to manufacture. In the inclined drawing machine used in this embodiment, it is preferable that the position of each rail part and rail connection part which comprise rail RiRo can be set freely, and a rail pattern can be changed arbitrarily.

In this embodiment, the holding | gripping tool 15 keeps a fixed space | interval with the holding | gripping tool 15 (gripping holes 15 of the upstream and downstream of a conveyance direction of a film) before and behind it, and runs at a constant speed. It is. Although the running speed of the holding | gripping tool 15 can be selected suitably, it is 1-150 m / min normally. The difference in traveling speed between the pair of left and right grippers (for example, gripper Ci · Co) is usually 1% or less, preferably 0.5% or less, and more preferably 0.1% or less of the travel speed. This is because if there is a difference in advancing speed between the left and right sides of the film at the stretching step exit, wrinkles and slippage occur at the exit step, so that the speed difference between the left and right grip ports is required to be substantially the same speed. In a general tenter device or the like, there is a speed nonuniformity occurring in an order of seconds or less depending on the period of the teeth of the sprocket driving the chain, the frequency of the driving motor, and the like, and often a nonuniformity of several percent is generated, but these are embodiments of the present invention. This does not apply to the speed difference described in.

In the diagonal drawing machine used by the manufacturing method of this embodiment, the rail which regulates the trajectory of a holding | gripping tool is requested | required large bending rate especially in the place where the conveyance of a film becomes oblique. For the purpose of avoiding interference between grippers due to abrupt bending or localized stress concentration, it is preferable that the trajectory of the gripper draws a smooth curve in the bent portion (curvature).

Thus, the diagonal stretch tenter used in order to give an elongate orientation to a long film can change the rail pattern variously, and can set the orientation angle of a film freely, and also the orientation axis (ground axis) of a film It is preferable that it is a tenter which can orientate in the left-right uniformly high precision over the width direction of a film, and can control film thickness and retardation with high precision.

Next, the extending | stretching operation | movement in the extending | stretching part 5 is demonstrated based on FIG. Both ends of a long film are gripped by right and left holding | gripping tool Ci * Co, and is conveyed in the heating zone Z with traveling of holding | gripping tool Ci * Co. The holding | gripping tool Ci * Co of the right and left is facing in the direction substantially perpendicular to the advancing direction (the conveyance direction D1 before extending | stretching) in the inlet part (position of A in drawing) of the extending | stretching part 5, It runs along the asymmetrical rail RiRo, respectively, and opens the film hold | maintained in the vicinity of the exit part (position of B in drawing) at the time of extending | stretching completion. In addition, the detail of the timing of a gripping opening is mentioned later. The film opened from the holding | gripping tool Ci * Co is wound up by the winding core by the film winding part 9 mentioned above. As described above, the pair of rails Ri · Ro each have an endless continuous trajectory, and the gripper Ci · Co which has opened the grip of the film at the exit of the stretched part 5 has an outer rail. It travels and is returned to a sequential inlet part sequentially.

At this time, since the rail RiRo is asymmetrical, in the example of FIG. 2, the left and right grippers Ci · Co facing each other at the position A in the drawing move the rail Ri side as they travel on the rail RiRo. The holding | gripping tool Ci becomes a positional relationship which precedes with respect to the holding | gripping tool Co which drive | works the rail Ro side.

That is, when the holding | gripping tool Ci reached | attained the position B at the time of extending | stretching completion of a film among the holding | gripping tools Ci and Co which are facing in the direction substantially perpendicular to the conveyance direction D1 before extending | stretching a film in the position of A in the figure And the straight line which connected holding | gripping tool Ci * Co are inclined by the angle (theta) L with respect to the direction substantially perpendicular to the conveyance direction D2 after extending | stretching of a film. By carrying out as mentioned above, elongate film will be diagonally stretched by the angle of (theta) L with respect to the width direction. Here, approximately vertical means that it exists in the range of 90 +/- 1 degree.

As mentioned above, in the manufacturing method of the diagonal stretched film of this embodiment, the one end side of the width direction of a film is gripped by the some holding | gripping tool 15 (including the holding | gripping tool Ci), and the other end side is plural. Holding by the holding | gripping tool 15 (including holding | gripping tool Co), it is relative to one holding | gripping tool 15 (for example, several holding | gripping tool 15 which runs along rail Ri) on the one end side and the other end side. The film is conveyed in an inclined direction with respect to the width direction by carrying out the above, and conveying a film by relatively delaying the other holding | gripping tool 15 (for example, several holding | gripping tool 15 which runs along rail Ro). It can be said that it includes a diagonal stretch process. In addition, in the following description, the side in which the holding | gripping tool travels relatively ahead of the one end side and the other end side of the width direction of a film is also called the "leading side", and the holding | gripping tool is a side which runs relatively delayed. Is also called the "delay side". For example, in FIG. 2, in the width direction of the film, the side on which the gripper Ci travels is the leading side, and the side on which the gripper Co travels is the delaying side.

Next, the detail of said heating zone Z is demonstrated. The heating zone Z of the extending | stretching part 5 is comprised from the preheating zone Z1, the extending zone Z2, and the heat fixing zone Z3. In the extending | stretching part 5, the film hold | maintained by holding | gripping tool Ci * Co passes through preheating zone Z1, extending zone Z2, and heat fixing zone Z3 in order.

The preheating zone Z1 refers to a section in which the holding sphere Ci · Co gripping both ends of the film runs while maintaining a constant distance from the left and right (in the width direction of the film) at the inlet portion of the heating zone Z.

The stretching zone Z2 refers to a section in which the above-described diagonal stretching step is performed. Under the present circumstances, you may extend | stretch a film in a longitudinal direction or a horizontal direction before and after diagonal stretch.

The heat fixation zone Z3 is a section in which the heat fixation step of fixing the optical axis (ground axis) of the film is performed after the completion of the oblique stretching step.

In addition, after extending | stretching the film, after passing through the heat setting zone Z3, you may pass the section (cooling zone) in which the temperature in a zone is set to the glass transition temperature Tg (degreeC) or less of the thermoplastic resin which comprises a film. At this time, in consideration of shrinkage of the film due to cooling, it may be a rail pattern that narrows the gap between the holding regions Ci and Co that face each other in advance.

Regarding the glass transition temperature Tg of the thermoplastic resin, the temperature of the preheating zone Z1 is Tg to Tg + 30 ° C, the temperature of the stretching zone Z2 is Tg to Tg + 30 ° C, and the temperature of the heat fixation zone Z3 is Tg-30 to Tg ° C. It is preferable to set.

Moreover, in order to control the thickness nonuniformity of the film of the width direction, you may provide a temperature difference in the width direction in extending zone Z2. In order to put a temperature difference in the width direction in a drawing zone, the method of adjusting the opening degree of the nozzle which blows a warm air into a thermostatic chamber so as to put a difference in the width direction, or heat-controlling by arrange | positioning a heater in the width direction is well-known. Method can be used. The lengths of the preheating zone Z1, the drawing zone Z2 and the heat fixing zone Z3 can be appropriately selected, and compared to the length of the drawing zone Z2, the length of the preheating zone Z1 is usually 100 to 150%, and the length of the heat fixing zone Z3 is usually 50 to 150. 100%.

In addition, when the width of the film before stretching is Wo (mm) and the width of the film after stretching is W (mm), the draw ratio R (W / Wo) in the stretching step is preferably 1.3 to 3.0, and more. Preferably it is 1.5-2.8. When a draw ratio exists in this range, the thickness nonuniformity of the width direction of a film will become small, and it is preferable. In the stretching zone Z2 of the oblique stretching tenter, when the stretching temperature is different in the width direction, the thickness nonuniformity in the width direction can be made a better level. In addition, the said draw ratio R is equal to the magnification W2 / W1 when the space | interval W1 of the both ends of the clip held by the tenter inlet part became the space | interval W2 in the tenter outlet part.

<Quality of Long Stretched Film>

In the elongate diagonal stretched film obtained by the manufacturing method according to the embodiment of the present invention, the orientation angle θ is inclined in a range of, for example, greater than 0 ° and less than 90 ° with respect to the winding direction, and has a width of at least 1300 mm. WHEREIN: It is preferable that the deviation of in-plane retardation Ro of the width direction is 3 nm or less, and the deviation of orientation angle | corner (theta) is less than 0.6 degrees.

That is, in the elongate diagonal stretched film obtained by the manufacturing method which concerns on embodiment of this invention, the deviation of in-plane retardation Ro is 3 nm or less and 1 nm or less in at least 1300 mm of the width direction. desirable. By setting the deviation of in-plane retardation Ro into the said range, when the elongate diagonal stretched film is bonded to a polarizer and made into a circularly polarizing plate, and this is applied to an organic electroluminescence display, the color nonuniformity by the leakage of the external light reflection light at the time of black display Can be suppressed. Moreover, when a long stretched film is used as a retardation film for liquid crystal display devices, it becomes possible to make display quality favorable, for example.

Moreover, in the elongate diagonal stretched film obtained by the manufacturing method which concerns on embodiment of this invention, it is preferable that the deviation of orientation angle | corner (theta) is less than 0.6 degrees and is less than 0.4 degrees in at least 1300 mm of the width direction. . When the inclination stretched film of the elongate shape of the angle of orientation θ of 0.6 or more is bonded to the polarizer to form a circularly polarizing plate, and this is fixed to an image display device such as an organic EL display device, light leakage occurs, resulting in contrast of contrast. It may reduce.

The in-plane retardation Ro of the elongate diagonal stretched film obtained by the manufacturing method which concerns on embodiment of this invention selects an optimal value by the design of the display apparatus used. Further, Ro is a value obtained by multiplying the average thickness d of the film by 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 (Ro = (nx-ny) × d )to be.

The average thickness of the elongated obliquely stretched film obtained by the production method according to the embodiment of the present invention is preferably 10 to 200 μm, more preferably 10 to 60 μm, particularly preferably from the viewpoint of mechanical strength or the like. Is 10 to 35 µm. Moreover, since the thickness nonuniformity of the width direction of the said diagonal stretched film affects the availability of winding, it is preferable that it is 3 micrometers or less, and it is more preferable that it is 2 micrometers or less.

<Polarizing plate>

4 is an exploded perspective view showing a schematic configuration of the polarizing plate 50 of the present embodiment. The polarizing plate 50 is laminated | stacked and laminated | stacked the polarizing plate protective film 51, the polarizer 52, and the retardation film 53 in this order. Although the polarizing plate protective film 51 is comprised, for example with a cellulose-ester film, you may be comprised with another transparent resin film (for example, cycloolefin resin). Moreover, the polarizing plate protective film 51 may be comprised with the optical compensation film which compensates for optical characteristics, such as a viewing angle enlargement.

As the polarizer 52, one obtained by stretching polyvinyl alcohol doped with iodine or a dichroic dye can be used. The film thickness of a polarizer is 5-40 micrometers, Preferably it is 5-30 micrometers, Especially preferably, it is 5-20 micrometers.

The retardation film 53 is comprised from the optical film of this embodiment, ie, the diagonal stretched film. The slow axis of the retardation film 53 inclines 10-80 degrees with respect to one side (for example, side 53a) of a rectangular film external form in a film plane. In addition, the said edge 53a is a side corresponding to the width direction of an elongate diagonal stretched film. The preferable range of the inclination angle of the slow axis with respect to the side 53a in a film plane is 30-60 degrees, More preferably, it is 45 degrees. The angle between the slow axis of the retardation film 53 and the absorption axis (or transmission axis) of the polarizer 52 is, for example, 10 to 80 °, preferably 15 to 75 °, more preferably 30 to 60 degrees, more preferably 45 degrees.

On the surface on the opposite side to the polarizer 52 of the retardation film 53, another layer (for example, a hard coat layer, a low refractive index layer, an antireflection layer, a liquid crystal (positive C-type plate)) may be appropriately provided according to the use. Moreover, the easily bonding layer may be provided in the surface on the polarizer 52 side of the retardation film 53.

As for the polarizing plate 50 of this embodiment, the elongate polarizing plate protective film 51, the elongate polarizer 52, and the elongate phase difference film 53 (elongate diagonal stretched film) are laminated | stacked in this order. An elongate polarizing plate may be sufficient, and the sheet-shaped polarizing plate which cut | disconnected the elongate polarizing plate 50 along the width direction perpendicular | vertical to a longitudinal direction may be sufficient.

The polarizing plate 50 can be produced by a general method. For example, the polarizer 52 and the retardation film 53 can be adhere | attached with an ultraviolet curable adhesive (UV adhesive), and the polarizing plate 50 can be produced. In addition, the retardation film 53 processed by alkali saponification is bonded to one surface of the polarizer 52 produced by dipping and stretching a polyvinyl alcohol-based film in an iodine solution, using a fully saponified polyvinyl alcohol aqueous solution (water pool). You may be. Moreover, also about adhesion | attachment of the polarizer 52 and the polarizing plate protective film 51, an ultraviolet curable adhesive or a water pool can be used.

<Composition of UV Curable Adhesive>

As an ultraviolet curable adhesive composition for polarizing plates, the photoradical polymerization type composition using photoradical polymerization, the photocationic polymerization type composition using photocationic polymerization, and the hybrid composition which used photoradical polymerization and photocationic polymerization together are known.

Examples of the radical photopolymerizable composition include a radical polymerizable compound containing a polar group such as a hydroxy group and a carboxy group, and a radical polymerizable compound not containing a polar group in a specific ratio, such as those described in Japanese Patent Application Laid-Open No. 2008-009329). This is known. In particular, the radically polymerizable compound is preferably a compound having an ethylenically unsaturated bond capable of radical polymerization. Preferred examples of the compound having an ethylenically unsaturated bond capable of radical polymerization include a compound having a (meth) acryloyl group. Examples of the compound having a (meth) acryloyl group include an N-substituted (meth) acrylamide compound, a (meth) acrylate compound, and the like. (Meth) acrylamide means an acrylamide or methacrylamide.

Moreover, as a photocationic polymerization type composition, (alpha) cationically polymerizable compound, ((beta)) photocationic polymerization initiator, ((gamma)) of wavelength longer than (380) as disclosed by Unexamined-Japanese-Patent No. 2011-028234, The ultraviolet curing adhesive composition containing the photosensitive agent which shows the maximum absorption to light, and each component of ((delta)) naphthalene type photosensitization adjuvant is mentioned. However, ultraviolet curable adhesives other than that may be used.

(1) pretreatment process

A pretreatment process is a process of performing an adhesion | attachment facilitation process to the adhesive surface with a polarizer in retardation film and a polarizing plate protective film (here, these are collectively called a "protective film"). Examples of easy adhesion treatment include corona treatment and plasma treatment.

(Application process of ultraviolet curable adhesive)

As an application | coating process of an ultraviolet curable adhesive agent, the said ultraviolet curable adhesive agent is apply | coated to at least one adhesive surface of a polarizer and a protective film. When apply | coating UV cure adhesive to the surface of a polarizer or a protective film directly, there is no special limitation in the coating method. For example, various wet coating methods, such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater, can be used. Moreover, after apply | coating (flexible) an ultraviolet curable adhesive agent between a polarizer and a protective film, the method of pressurizing with a roller etc. and uniformly pressing an ultraviolet curable adhesive agent can also be used.

(2) bonding process

After apply | coating an ultraviolet curable adhesive by the said method, it processes in a bonding process. In this bonding process, when UV cure adhesive is apply | coated to the surface of a polarizer in the previous application | coating process, a protective film is overlaid there, for example. Moreover, in the case of the system which apply | coats an ultraviolet curable adhesive agent on the surface of a protective film, a polarizer superimposes on it. In addition, when an ultraviolet curable adhesive agent is cast between a polarizer and a protective film, a polarizer and a protective film overlap in that state. And normally, in this state, it presses by a pressure roller etc. from the protection film side of both surfaces. As the material of the pressure roller, a metal, rubber or the like can be used. The pressure rollers arranged on both surfaces may be the same material or may be different materials.

(3) curing process

In the curing step, ultraviolet rays are irradiated to the uncured ultraviolet curable adhesive to form a cationically polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radically polymerizable compound (for example, an acrylate compound or an acrylamide system). Compound, etc.), the ultraviolet curable adhesive layer is cured, and the polarizer and the protective film superimposed through the ultraviolet curable adhesive are adhered. In the structure of this embodiment which bonds a protective film to both surfaces of a polarizer, irradiating an ultraviolet-ray and hardening | curing both ultraviolet curable adhesives simultaneously simultaneously in the state which superimposed a protective film on both surfaces of a polarizer through an ultraviolet curable adhesive agent, respectively. It is advantageous.

Arbitrary appropriate conditions can be employ | adopted as long as the irradiation conditions of an ultraviolet-ray are conditions which can harden an ultraviolet curable adhesive agent. It is preferable that it is the range of 50-1500mJ / cm <2> by the accumulated light quantity, and, as for the irradiation amount of an ultraviolet-ray, it is more preferable that it is the range which is 100-500mJ / cm <2>.

When performing the manufacturing process of a polarizing plate in a continuous line, although a line speed changes with the hardening time of an adhesive agent, Preferably it is the range of 1-500 m / min, More preferably, it is the range of 5-300 m / min, More preferably, It is the range of 10-100 m / min. If line speed is 1 m / min or more, productivity can be ensured, damage to a protective film can be suppressed, and the polarizing plate excellent in durability can be manufactured. Moreover, when a line speed is 500 m / min or less, hardening of an ultraviolet curable adhesive becomes enough, it can be provided with the target hardness, and can form the ultraviolet curable adhesive bond layer excellent in adhesiveness.

<Organic EL display device>

5 is a cross-sectional view illustrating a schematic configuration of an organic EL display device 100 that is an example of a display device of the present embodiment. In addition, the structure of the organic electroluminescence display 100 is not limited to this.

The organic EL display device 100 is configured by forming the polarizing plate 301 on the organic EL element 101 as a display cell through the adhesive layer 201. The organic EL element 101 has the metal electrode 112, the light emitting layer 113, the transparent electrode (ITO etc.) 114, and the sealing layer 115 in order on the board | substrate 111 using glass, polyimide, etc. Consists of. In addition, the metal electrode 112 may be comprised from the reflection electrode and the transparent electrode.

The polarizing plate 301 is made by laminating the λ / 4 phase difference film 311, the adhesive layer 312, the polarizer 313, the adhesive layer 314, and the protective film 315 in order from the organic EL element 101 side. The polarizer 313 is sandwiched by the λ / 4 retardation film 311 and the protective film 315. The angle formed by the transmission axis (or absorption axis) of the polarizer 313 and the slow axis of the lambda / 4 phase difference film 311 including the elongated obliquely stretched film of the present embodiment is about 45 ° (or 135 °). The polarizing plate 301 (circular polarizing plate) is comprised by bonding both so that it may become. In addition, the protective film 315 of the polarizing plate 301, the polarizer 313, and (lambda) / 4 phase (s) difference film 311 are the polarizing plate protective film 51, the polarizer 52, and the phase difference film of the polarizing plate 50 of FIG. It corresponds to 53, respectively.

It is preferable that the cured layer is laminated | stacked on the said protective film 315. The cured layer not only prevents scratches on the surface of the organic EL display device, but also has an effect of preventing warping by the polarizing plate 301. Moreover, on the hardened layer, you may have a reflection prevention layer. The thickness of the organic EL element 101 itself is about 1 μm.

In the above configuration, when a voltage is applied to the metal electrode 112 and the transparent electrode 114, electrons are injected into the light emitting layer 113 from the electrode serving as the cathode among the metal electrode 112 and the transparent electrode 114. Holes are injected from the electrode serving as the anode, and both are recombined in the light emitting layer 113, whereby light emission of visible light corresponding to the light emission characteristics of the light emitting layer 113 occurs. The light generated in the light emitting layer 113 is directly or reflected by the metal electrode 112, and then is taken out through the transparent electrode 114 and the polarizing plate 301.

In general, in an organic EL display device, an element (organic EL element) which is a light emitting body is formed by stacking a metal electrode, a light emitting layer, and a transparent electrode in order on a transparent substrate. Here, a light emitting layer is a laminated body of various organic thin films, For example, the laminated body of the hole injection layer containing a triphenylamine derivative etc., and the light emitting layer containing fluorescent organic solids, such as anthracene, and such a light emitting layer and perylene The structure which has various combinations, such as the laminated body with the electron injection layer containing a derivative | guide_body, etc., these laminated bodies of a hole injection layer, a light emitting layer, and an electron injection layer, is known.

In the organic EL display device, by applying a voltage to the transparent electrode and the metal electrode, holes and electrons are injected into the light emitting layer, and energy generated by recombination of these holes and electrons excites the fluorescent material, and the excited fluorescent material is based on It emits light on the principle of emitting light when returning to the state. The mechanism of intermediate recombination is the same as that of a general diode, and as can be expected from this, the current and the emission intensity exhibit strong nonlinearity accompanied by rectification with respect to the applied voltage.

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

In the organic EL display device having such a configuration, the light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the light emitting layer also transmits light almost completely like the transparent electrode. As a result, the light incident on the surface of the transparent substrate at the time of non-luminescence, and the light reflected through the transparent electrode and the light emitting layer and reflected from the metal electrode again comes out to the surface side of the transparent substrate, therefore, when viewed from the outside, The display surface looks like a mirror.

The circularly polarizing plate of the present embodiment is suitable for an organic EL display device in which such external light reflection is particularly problematic.

That is, at the time of non-emission of the organic EL element 101, the external light incident from the outside of the organic EL element 101 by indoor lighting or the like is half absorbed by the polarizer 313 of the polarizing plate 301, and the other half. Is transmitted as linearly polarized light, and is incident on the λ / 4 retardation film 311. The light incident on the λ / 4 retardation film 311 is λ / 4 because the transmission axis of the polarizer 313 and the slow axis of the λ / 4 retardation film 311 cross each other at 45 ° (or 135 °). Transmitting the retardation film 311 is converted into circularly polarized light.

The circularly polarized light emitted from the λ / 4 retardation film 311 is inverted in phase by 180 degrees when specularly reflected by the metal electrode 112 of the organic EL element 101, and is reflected as circularly polarized light in the reverse rotation direction. The reflected light is converted into linearly polarized light perpendicular to the transmission axis of the polarizer 313 (parallel to the absorption axis) by being incident on the λ / 4 retardation film 311, so that all of the reflected light is absorbed by the polarizer 313 and is moved outward. It will not go out. That is, the reflection of the external light in the organic EL element 101 can be reduced by the polarizing plate 301.

<Liquid crystal display device>

6 is a cross-sectional view showing a schematic configuration of a liquid crystal display device 400 that is another example of the display device of the present embodiment. The liquid crystal display device 400 is configured by arranging the polarizing plate 402 on one surface side of the liquid crystal cell 401.

 The liquid crystal cell 401 is a display cell in which a liquid crystal layer is sandwiched between a pair of substrates. In addition, the polarizing plate 402 and another polarizing plate arranged in a cross nicol state and a backlight for illuminating the liquid crystal cell 401 are provided on the side opposite to the polarizing plate 402 with respect to the liquid crystal cell 401. , They omitted the city.

In addition, the liquid crystal display device 400 may have the front window 403 on the side opposite to the liquid crystal cell 401 with respect to the polarizing plate 402. The front window 403 becomes an exterior cover of the liquid crystal display device 400, and is comprised, for example from cover glass. Between the front window 403 and the polarizing plate 402, the filler 404 which consists of ultraviolet curable resin, for example is filled. In the absence of the filler 404, since an air layer is formed between the front window 403 and the polarizing plate 402, by the reflection of light at the interface between the front window 403 and the polarizing plate 402 and the air layer, The visibility of a display image may fall. However, since the air layer is not formed between the front window 403 and the polarizing plate 402 by the filler 404, a decrease in the visibility of the display image due to the reflection of light at the interface can be avoided.

The polarizing plate 402 has a polarizer 411 which transmits predetermined linearly polarized light. On one side of the polarizer 411 (the side opposite to the liquid crystal cell 401), the λ / 4 retardation film 413 and the cured layer 414 containing the ultraviolet curable resin are in this order via the adhesive layer 412. It is stacked. In addition, the protective film 416 is bonded to the other surface side (liquid crystal cell 401 side) of the polarizer 411 via the adhesive layer 415.

 The polarizer 411 is obtained by, for example, dyeing a polyvinyl alcohol film with a dichroic dye and stretching the film at high magnification. After the polarizer 411 is subjected to alkali treatment (also referred to as saponification treatment), the lambda / 4 phase difference film 413 is bonded to one surface side via the adhesive layer 412, and the protective film 416 is bonded to the other surface side ( 415). In addition, the protective film 416 of the polarizing plate 402, the polarizer 411, and (lambda) / 4 phase (s) difference film 413 are the polarizing plate protective film 51, the polarizer 52, and the phase difference film of the polarizing plate 50 of FIG. It corresponds to 53, respectively. The adhesive layer 412 占 415 is a layer containing, for example, a polyvinyl alcohol adhesive (PVA adhesive, water glue), but may be a layer containing an ultraviolet curable adhesive (UV adhesive).

(lambda) / 4 phase (s) difference film 413 is a layer which provides the in-plane phase difference of about 1/4 of a wavelength with respect to transmitted light, and is comprised from the optical film (inclined stretched film) of this embodiment, The thickness is, for example 10-70 micrometers. In addition, the angle (intersection angle) which the slow axis of (lambda) / 4 phase (s) difference film 413 and the absorption axis of the polarizer 411 make is 30-60 degrees, for example, More preferably, it is 45 degrees. As a result, the linearly polarized light from the polarizer 411 is converted into circularly polarized light or elliptical polarized light by the λ / 4 retardation film 413.

The hardened layer 414 (also called a hard coat layer) is comprised from active energy ray hardening type resin (for example, ultraviolet curable resin).

The protective film 416 is comprised from the resin film containing a cellulose resin (cellulose polymer), an acrylic resin, cyclic polyolefin (COP), and polycarbonate (PC), for example. The protective film 416 is simply provided as a film for protecting the back side of the polarizer 411, but may be provided as an optical film that also serves as a retardation film having a desired optical compensation function.

In addition, in the case of a liquid crystal display device, the other polarizing plate arrange | positioned on the opposite side to the polarizing plate 402 with respect to the liquid crystal cell 401 (liquid crystal cell) is comprised by clamping the surface of a polarizer with two optical films, but As a polarizer and an optical film, the thing similar to the polarizer 411 and the protective film 416 of the polarizing plate 402 can be used.

Moreover, the easily bonding layer for improving the adhesiveness of (lambda) / 4 phase (s) difference film 413 may be provided in the adhesive layer 412 side of (lambda) / 4 phase (s) difference film (413). The easy bonding layer is formed by performing an adhesion facilitating treatment on the adhesive layer 412 side of the λ / 4 retardation film 413. Examples of easy adhesion treatment include corona treatment (discharge) treatment, plasma treatment, flame treatment, etro treatment, glow treatment, ozone treatment, primer coating treatment, and the like. Among these ease of adhesion treatment, from the viewpoint of productivity, corona treatment and plasma treatment are preferred as the ease of adhesion treatment.

As described above, the polarizing plate 402 is located on the viewing side with respect to the liquid crystal cell 401, and the λ / 4 phase difference film 413 of the polarizing plate 402 is opposite to the liquid crystal cell 401 with respect to the polarizer 411. In the configuration of the liquid crystal display device 400 positioned at, the linearly polarized light emitted from the liquid crystal cell 401 and transmitted through the polarizer 411 on the viewing side is circularly or elliptically polarized by the λ / 4 retardation film 413. Is converted. For this reason, when an observer attaches polarized sunglasses and observes the display image of the liquid crystal display device 400, even if the transmission axis of the polarizer 411 and the transmission axis of the polarized sunglasses form any angle, the transmission of the polarized sunglasses The display image can be observed by guiding a component of light parallel to the axis to the observer's eye.

<About dimensional change rate of inclined stretched film>

Next, the dimension change rate of the diagonal stretched film (optical film) used as a retardation film (for example, (lambda) / 4 phase (s)) film of the polarizing plate mentioned above is demonstrated.

Fast axis direction and slow axis direction before and after leaving the optical film of this embodiment, ie, an optical film in which the slow axis was inclined by 10 to 80 degrees with respect to one side of the film appearance in the film surface at 90 ° C for 120 hours. The dimensional change rate of is referred to as ΔD _F (%) and ΔD _{L (} %), respectively. That is, in an optical film, it is the distance between two points arrange | positioned in a fast axis direction, and the distance before leaving an optical film at 90 degreeC for 120 hours, and after leaving it is called a1 (mm) and a2 (mm), respectively, In an optical film, it is the distance between two points arrange | positioned in a slow axis direction, and when the distance before leaving an optical film at 90 degreeC for 120 hours, and after leaving it, respectively is b1 (mm) and b2 (mm),

ΔD _F = {(a2-a1) / a1} × 100

ΔD _L = {(b2-b1) / b1} × 100

to be. And in this embodiment, in the center part and both ends of the direction along the said one side of a film external form,

0% ≦ ΔD _F <0.5%. (One)

ΔD _L <0%. (2)

Are satisfied.

By satisfying the above conditional expression (1) (2) with respect to the dimensional change rates ΔD _F and ΔD _L in the fast axis direction and the slow axis direction of the optical film, the optical film expands in the fast axis direction in a high temperature environment or changes in dimensions. Instead, it contracts in the slow axis direction.

In addition, the optical film shrinks in the slow axis direction under a high temperature environment for the following reasons. The slow axis direction is the same as the stretching direction, and after stretching, tensile stress remains in the slow axis direction in the optical film. In the high temperature environment, since the tensile stress is relaxed, the optical film shrinks in the slow axis direction. The reason why the optical film does not expand or change in the axial direction in a high temperature environment is that the shrinkage stress in the fastening axis direction or the shrinkage and tensile stress in the fastening axis direction do not remain after stretching. The details of the means for realizing such a dimensional change rate ΔD _F will be described later.

By satisfying Conditional Expression (1) (2), since the optical film of the present embodiment does not shrink in the fast axis direction under a high temperature environment, even if there is shrinkage in the slow axis direction under a high temperature environment, the dimensional change (shrinkage) as a whole film Can be suppressed as compared with the film shrinking in both directions in the fast axis direction and the slow axis direction under a high temperature environment. When the optical film and polarizer of this embodiment are adhere | attached with an adhesive agent so that the slow axis of an optical film and the absorption axis (or transmission axis) of a polarizer may be a desired angle (for example, 45 degrees), thereby manufacturing a polarizing plate Also, due to the dimensional change of the optical film, curling may occur on the polarizing plate, or the adhesion of the optical film to the polarizer is deteriorated, and the quality of the polarizing plate can be suppressed, such as the optical film peeling off from the polarizer. .

That is, when the said adhesive agent is UV cure adhesive, for example, it will become a high temperature environment by heating for ultraviolet irradiation or hardening promotion. On the other hand, when the said adhesive agent is water-based adhesive agents, such as a water pool, it turns into a high temperature environment by the heating or drying for hardening promotion of the adhesive agent. Even in an environment where the temperature becomes high at the time of such adhesion, the optical film of the present embodiment can suppress dimensional change (shrinkage) as the entire film without shrinking in the fast axis direction as described above, so that the curl and optical film of the polarizing plate The adhesive fall of can be suppressed.

In this way, by suppressing curl of the polarizing plate, in the organic EL display device to which the polarizing plate is applied, light leakage due to reflection of external light at the time of black display can be suppressed. Moreover, in the liquid crystal display device corresponding to polarized sunglasses which arrange | positioned the said polarizing plate in the visual recognition side of a liquid crystal cell, it can suppress that distortion arises in the image visually recognized through the said polarizing plate, and can suppress the fall of the visibility of a display image Can be.

In recent years, in order to improve visibility even from any angle, a high retardation film having a phase difference of 10000 nm or more, including polyethylene terephthalate and polyethylene naphthalate, has also been proposed. Even when constituting a polarizing plate using such a film, if curl occurs in the polarizing plate due to the dimensional change of the film, the visibility of the display image is lowered. However, also in such a film, since satisfying said conditional formula (1) (2), since the dimensional change of the whole film in high temperature environment can be suppressed and the curl of a polarizing plate can be suppressed, a high retardation film is applied Also in the said liquid crystal display device, the fall of visibility can be suppressed.

Moreover, when the dimensional change rate (DELTA) D _F of a fast axis direction becomes 0.5% or more, the dimensional change (expansion) of a fast axis direction will become large too much compared with the dimensional change (shrinkage) of the slow axis direction in a high temperature environment, Distortion occurs, thereby causing a curl to occur in the polarizing plate or peeling of the optical film as described above. In this reason, the condition (1), specifies the upper limit of the dimensional change rate ΔD _F in the fast axis direction of 0.5%.

Moreover, since the optical film of this embodiment is a film whose residual solvent amount becomes 60 ppm or less, the film design which satisfy | fills said conditional formula (1) (2) simultaneously is attained. In more detail, it is as follows.

In film-forming of the film by a solution casting film forming method, since the solvent is used for film-forming, the amount of residual solvent of the film formed into a film exceeds 60 ppm much. As described above, the film formed by the solution casting film forming method has a low resin density and easily extends in both directions in the slow axis direction and the fast axis direction at the time of diagonal stretching, so that after slow stretching, the slow axis direction and the fast axis Tensile stress remains in both directions. And as a result of the said tension stress being relaxed under high temperature environment, the said film shrinks in both directions of a slow axis direction and a fast axis direction. For this reason, even if the said optical film satisfies conditional formula (2), it will not satisfy | fill conditional formula (1).

On the other hand, the film in which the amount of residual solvent becomes 60 ppm or less can be formed into a film, for example by the melt casting film forming method. Since the film formed by the melt casting film method has a higher resin density than the film formed by the melt casting film method (components other than the solvent are the same), the film formed by the melt casting film method extends in the fast axis direction during diagonal stretching. It becomes difficult, and it extends forcibly by the force of an extending | stretching direction to a slow axis direction. For this reason, in the film after diagonal stretching, tensile stress remains in the slow axis direction, while tensile stress hardly remains in the fast axis direction. Therefore, even if the film shrinks in the slow axis direction under a high temperature environment, it becomes difficult to shrink in the fast axis direction, so that it is possible to design a film that satisfies the conditional formula (1) (2) at the same time.

From the viewpoint of reliably increasing the density of the resin contained in the film and enabling the film design to satisfy the conditional formula (1) (2) reliably, the preferred range of the residual solvent amount of the optical film of the present embodiment is, 10 ppm or less.

In addition, the horizontally stretched film is a film stretched in the width direction, for example, but in the case of stretching, since the tension for conveying the film is applied in the conveying direction (length direction), the slow-axial direction (stretching direction) is applied to the film after stretching. Tensile stress remains in both directions in the phosphorus width direction and in the fast axis direction (the conveying direction). Therefore, as a result of the relaxation of the tensile stress under the high temperature environment of the film, the film shrinks in both directions in the slow axis direction and the fast axis direction, so that the conditional expression (1) is not satisfied.

In addition, a longitudinally stretched film is a film extended | stretched in the conveyance direction (length direction), At the time of extending | stretching, although extending in a longitudinal direction (ground axis direction), it can be considered that it shrinks in the width direction (fastening axis direction), It is not actively contracted in the direction, and the contraction force in the fast axis direction is considered to be small. For this reason, the residual stress in the fast axis direction is small, and even if the residual stress in the fast axis direction is relaxed under the high temperature environment of the film, the film does not expand in the fast axis direction. On the contrary, under the high temperature environment, since the shrinkage in the slow axis direction is large, the entire film tends to shrink, and therefore, it is thought that the film shrinks slightly in the fast axis direction. Therefore, the longitudinally stretched film also does not satisfy the conditional formula (1).

As described above, the optical film of the present embodiment that satisfies the conditional formula (1) (2) at the same time is inclined stretching formed by stretching methods other than transverse stretching and longitudinal stretching, that is, stretching in an oblique direction with respect to the width direction of the long film. It is realized by the film.

Moreover, it is preferable that the optical film of this embodiment further satisfy | fills the following conditional formula (1a). In other words,

0% <ΔD _F <0.5% (1a)

to be.

Since the optical film that satisfies the conditional formula (1a) expands in the fast axis direction under a high temperature environment, even if there is a shrinkage in the slow axis direction under a high temperature environment, the dimensional change (shrinkage) as a whole film is reduced in the fast axis direction and under a high temperature environment. The film can be reliably suppressed as compared with the film shrinking in both directions in the slow axis direction. Therefore, when the optical film and the polarizer are bonded together to form a polarizing plate, the curls are reliably suppressed, and light leakage due to external light reflection when the polarizing plate is applied to an organic EL display device, or the polarizing plate is a liquid crystal for polarizing sunglasses. The fall of the visibility at the time of applying to a display apparatus can be suppressed reliably.

By the way, an optical film (inclined stretched film) in which the slow axis is inclined by 10 to 80 ° with respect to one side (for example, the side corresponding to the width direction of the long film) of the film outline (for example, rectangular) within the film plane. In the center part of the direction along one said side, the dimensional change rate of the up-axis direction before and after leaving this optical film to stand at 90 degreeC for 120 hours as (DELTA) D _FC (%), in one end portion (e.g. the side end that is followed during oblique stretching), the optical film and the truth dimensional change in the axial direction in the before and after left to stand at 90 ℃ 120 hours, as ΔD _{-E1 F} (%), a dimensional change in the (end to which the retarded side at the time for example oblique stretching), the other end portion of the along the one side direction, the optical film to stand at 90 ℃ 120 sigan fast axis in the front-rear direction, ΔD _{F - When it is E2} (%),

(ΔD_{F -E1}+ ΔD_{F -E2}) / 2> ΔD_{F - C} … (3)

It is desirable to further satisfy. The reason is as follows.

When the optical film of this embodiment is adhere | attached with a polarizer through an adhesive agent and comprises a polarizing plate, even if it is an ultraviolet curable adhesive or water glue, an adhesive agent shrinks at the time of hardening (under high temperature environment) normally. At this time, in the adhesion using the ultraviolet curable adhesive, when irradiating ultraviolet rays which are active energy rays, the amount of ultraviolet light received at the width center portion (corresponding to the width center portion of the optical film) and the width end portion (corresponding to the width edge portion of the optical film) of the adhesive There are many cases where a difference occurs, and the amount of ultraviolet light received is greater in the center portion of the width than in the width portion. For this reason, it is estimated that the cure shrinkage of the adhesive agent at the time of ultraviolet irradiation is larger in the width center portion than in the width edge portion.

In addition, the difference in the amount of ultraviolet light received at the width center portion and the width edge portion is different from the width center portion in either width direction with respect to the normal of the coating surface of the adhesive in the width center portion when a UV light source for irradiating ultraviolet rays with a width smaller than the required width is used. This is because the ultraviolet rays are irradiated only at one side in the width direction with respect to the normal of the coated surface of the adhesive at the width end, while the ultraviolet rays are irradiated at the side. Moreover, in order to reduce the fluctuation | variation in the width direction of an ultraviolet light reception quantity, the method of irradiating an ultraviolet-ray in the width | variety which is larger than a required width can also be considered, but this method requires a large UV lamp, and becomes very expensive. It is not preferable at this point.

Moreover, even at the time of the heating for accelerate | stimulating hardening of an adhesive agent (ultraviolet-curable adhesive agent, a water pool), in a width center part, heat is easy to stay compared with the width edge part, and it is known that temperature falls at the width edge part. For this reason, even when the heating for promoting the curing of the adhesive is performed, the curing shrinkage of the adhesive is estimated to be larger in the width center portion than in the width edge portion.

The method corresponding to the deformation | transformation of the polarizing plate by hardening shrinkage | contraction of an adhesive agent was examined, ensuring sufficient adhesive force by an adhesive agent between an optical film and a polarizer. As a result, in the width direction of an optical film, it differs in the expansion amount of a positive axis direction. It was found that the curl of the polarizing plate can be more suppressed in the entire width direction by placing the. FIG. 7: has shown typically the behavior in the width center part and width edge part of the adhesive agent and optical film at the time of hardening of an adhesive agent in this embodiment. Since shrinkage and expansion are mutually opposite behaviors, for example, at the same position in the width direction, when the shrinkage of the adhesive is large and the expansion of the optical film is large, the polarizing plate is concave so that the adhesive side is concave (the optical film side is convex). Curl).

By satisfying the above conditional expression (3), the expansion in the fast axis direction of the optical film becomes small at the width center portion where the shrinkage of the adhesive is large, and the expansion in the fast axis direction of the optical film is reduced at the width end where the shrinkage of the adhesive is small. Gets bigger Thereby, in a width center part, it becomes possible to suppress that a polarizing plate is going to curl by big shrinkage | contraction of an adhesive agent by small expansion in the fast-axis direction of an optical film. Similarly, it is also possible to suppress the polarizing plate from curling due to the large expansion in the fast axis direction of the optical film by the small shrinkage of the adhesive agent at the width end. As a result, the curl of a polarizing plate can be suppressed more in the whole width direction. Moreover, by suppressing the curl of a polarizing plate more, adhesiveness with the optical film and polarizer by an adhesive agent can also be fully ensured, and it becomes possible to suppress peeling of an optical film reliably.

It is preferable that the optical film of this embodiment is elongate shape, and the direction along one said side of a film external shape is the width direction perpendicular | vertical to a longitudinal direction in the film surface of an optical film. In this case, an elongate optical film that satisfies the conditional expression (1) (2) can be realized in the central portion and both ends of the width direction with respect to the dimensional change rates ΔD _F and ΔD _L. Moreover, a polarizing plate can be manufactured by a roll-to-roll system using such an elongate optical film.

As for the polarizing plate (for example, the polarizing plate 301 of FIG. 5, the polarizing plate 402 of FIG. 6) of this embodiment, the optical film (for example, (lambda / 4 phase difference film 311 * 413)) of this embodiment mentioned above And a polarizer (for example, polarizers 313 占 411). The said optical film is located in one side with respect to a polarizer so that a slow axis may cross | intersect the absorption axis (or transmission axis) of a polarizer in a film plane. Since the optical film of this embodiment can suppress the dimensional change of the whole film, without shrinking in the fast axis direction in a high temperature environment, even when this optical film and a polarizer are bonded and a polarizing plate is produced, the high temperature at the time of adhesion is carried out. Peeling of the curl of a polarizing plate and optical film resulting from the dimensional change of an optical film in an environment can be suppressed.

Therefore, the display cell is the organic EL element 101, and the λ / 4 phase difference film 311 of the polarizing plate 301 is positioned on the organic EL element 101 with respect to the polarizer 313. ), Light leakage due to external light reflection at the time of black display can be suppressed by suppressing curl of the polarizing plate 301.

In addition, the display cell is a liquid crystal cell 401, and the λ / 4 phase difference film 413 of the polarizing plate 402 is located on the side opposite to the liquid crystal cell 401 with respect to the polarizer 411. In 400, by suppressing the curl of the polarizing plate 402, it is possible to suppress the occurrence of distortion in the image visually recognized through the polarizing plate 402, and to suppress the deterioration of the visibility of the display image.

<Means for realizing the dimensional change rate in the fast axis direction>

Next, in the optical film of the above-described embodiment, with respect to the means for implementing the fast axis _F of the dimensional change rate ΔD direction specified by the conditional expression (1), will be described in detail.

(Setting of force (tension) in the conveying direction applied to both ends in the width direction at the time of inclination stretching)

FIG. 8: shows typically the force of the conveyance direction applied to the both ends of the width direction of the elongate film in the extending | stretching part 5 of the manufacturing apparatus 1 of the diagonal stretched film shown in FIG. In the extending | stretching part 5, both ends of the width direction of a long film are hold | gripping with a pair of holding | gripping tool Ci * Co, one gripper Ci is relatively advanced with respect to the other holding | gripping tool Co, and a long film is in-plane By bending and conveying in this, the long film is stretched in the diagonal direction with respect to the width direction, and the diagonal stretch process which acquires the diagonal stretched film which comprises the said optical film is performed.

Here, before the diagonal stretching (for example, in the preheating zone Z1), at each end portion in the width direction of the elongated film, a force applied to the conveying direction by the holding of each gripper Ci · Co and the movement in the conveying direction, Let each be the same Tr (N). In addition, during the diagonal stretching (for example, in the stretching zone Z2), at each end portion in the width direction of the elongated film, the holding and conveying directions of the holding tool Co on the side which is relatively delayed and the holding tool Ci on the relatively preceding side are held. The force exerted on the conveyance direction by the movement to is called to (N) and Ti (N), respectively. At this time, in the above-described oblique stretching step,

(Ti-Tr) / Tr? (A)

(Tr-To) /Tr≧1.5... (B)

The long film is stretched in the inclined direction with respect to the width direction so as to satisfy. Incidentally, the conditional expressions (A) and (B) may be modified as in the following conditional expressions (A ') and (B'), respectively. In other words,

Ti≥2.7Tr... (A ')

To≤-0.5Tr... (B ')

to be.

Moreover, the holding | gripping tool Ci * Co is attached to the chain which moves along the rail RiRo in the extending | stretching part 5, The said chain is each zone (preheating zone Z1, extending zone Z2, heat fixing zone Z3). ) Is moved by the rotation of the driving roller. The force Tr, Ti, To can be replaced by the driving force of the motor for rotating the drive roller in each zone. In this embodiment, the conditional expressions (A) and (B) are satisfied by controlling the driving force. An optical film (inclined stretched film) is obtained.

By satisfying conditional expressions (A) and (B) (or by satisfying conditional expressions (A ') and (B'), the conveying direction applied during the inclined stretching at the end of the longitudinal direction leading side of the long film before the inclined stretching. While the force of increases, the force in the conveying direction applied during the oblique stretching decreases before the oblique stretching at the end of the delay side, and furthermore, the amount of change in the conveying direction (increased amount) and the delay in the preceding side edge. The change amount (reduction amount) of the force in the conveyance direction at the side edge part is also large.

By performing oblique stretching under such conditions, the film extends in the direction of the oblique stretching (in the ground axis direction) at each position in the width direction of the elongated film (at least in the central portion and both ends of the width direction), In this case, it is possible to create a state in which the film shrinks in balance with the tension during conveyance or in balance with the tension, so that the film does not extend or shrink. At this time, the conveyance direction and the fast axis direction are not necessarily coincident with each other. However, even if both are shifted, the amount of shift is small, so that the film shrinks in the conveyance direction, thereby leaving a stress that shrinks in the fast axis direction. . Moreover, in the film which does not extend nor shrink | contract in a conveyance direction, the film which does not extend or shrink | contract mostly in the fast-axis direction can be obtained.

Therefore, in a high temperature environment, the residual stress (shrinkage stress) can be alleviated in the fast axis direction to prevent the film from expanding, neither expanding nor shrinking, and thus the dimensional change rate ΔD in the fast axis direction defined by the above Conditional Expression (1). _F can be realized.

(Cooling of the delay end side at the time of inclination stretching)

9 schematically shows another configuration of the stretching section 5. The stretching portion 5 may have a cooling mechanism 21. In the diagonal stretch process in the extending | stretching part 5, the cooling mechanism 21 cools the edge part gripped by the holding | gripping tool Co of the side which retards relatively among each edge part of the width direction of an elongate film. Such a cooling mechanism 21 can be comprised, for example with the blowing mechanism (cooler, fan, etc.) which blows cold air into a long film.

In the diagonal stretching step, shrinkage stress can be imparted to the film end by cooling the film end on the delay side by the cooling mechanism 21. Thereby, the shrinkage stress remaining in the fast axis direction can be further increased by the diagonal stretching that satisfies the conditional expressions (A) and (B) described above. Therefore, under a high temperature environment, the film can be further expanded in the fast axis direction of the inclined stretched film by relaxation of residual stress (shrinkage stress), and the dimensional change rate? D _F in the fast axis direction defined by conditional formula (1) is determined. It is possible to realize reliably.

(Multilevel slanted stretching)

10 schematically shows another configuration of the stretching section 5. In the diagonal stretch process by the extending | stretching part 5, a long film is oriented so that a slow axis may orientate at an orientation angle (for example, 60 degrees) larger than the desired orientation angle (for example, 45 degrees) with respect to the width direction of a long film. After extending | stretching diagonally, you may diagonally stretch a long film so that a slow axis may orientate at a desired orientation angle (for example, 45 degrees). Such multistep diagonal stretching can be realized by appropriately changing the rail pattern of the stretching portion 5.

In the oblique stretching step, the larger the stretching angle (orbital angle at bending), that is, the larger the orientation angle of the slow axis due to the oblique stretching, the larger the tensile stress in the slow axis direction, and the shrinkage stress in the fast axis direction Is increased. In this way, once a large shrinkage stress is generated in the fast axis direction, a large shrinkage stress can still remain even though the stretching angle is reduced (although the shrinkage stress is somewhat reduced). Therefore, under a high temperature environment, the film can be further expanded in the fast axis direction of the inclined stretched film by relaxation of residual stress (shrinkage stress), and the dimensional change rate? D _F in the fast axis direction defined by conditional formula (1) is determined. It is possible to realize reliably. At this time, the cooling of the delay side end is not essential, but the effect can be further enhanced by cooling the delay side end together with the multi-step diagonal stretching.

<Example>

Hereinafter, although the specific Example of this invention is described, this invention is not limited to these Examples.

[Production of long film]

(Production of long film A1)

The polycarbonate-type resin film (PC film) as long film A1 was produced with the following manufacturing method (melt casting film forming method).

The polymerization was carried out using a batch polymerization apparatus comprising two vertical reactors with a stirring blade and a reflux condenser controlled at 100 ° C. 9,9- [4- (2-hydroxyethoxy) phenyl] fluorene (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenylcarbonate (DPC) and magnesium acetate tetrahydrate Was added at a molar ratio such that BHEPF / ISB / DEG / DPC / magnesium acetate = 0.348 / 0.490 / 0.162 / 1.005 / 1.00 × 10 ⁻⁵ . After the inside of the reactor was sufficiently nitrogen-substituted (oxygen concentration of 0.0005 to 0.001 vol%), heating was performed with a heat medium, and stirring was started when the internal temperature reached 100 ° C. 40 minutes after the start of the temperature increase, the internal temperature was reached at 220 deg. C, the pressure was controlled to maintain this temperature, and the pressure reduction was started. After reaching the temperature at 220 deg. C, the temperature was set to 13.3 kPa. The by-product phenol vapor with the polymerization reaction was led to a reflux cooler at 100 ° C, the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the uncondensed phenol vapor was led to a condenser at 45 ° C to recover.

Nitrogen was introduced into the first reactor and once back to atmospheric pressure, then the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Subsequently, the temperature increase and pressure reduction in a 2nd reactor were started, and it was set as 240 degreeC of internal temperature and the pressure of 0.2 kPa in 50 minutes. Then, polymerization was advanced until it became a predetermined stirring power. When the predetermined power was reached, nitrogen was introduced into the reactor and back-pressured, the reaction solution was taken out in the form of strands, pelletized by a rotary cutter, and the BHEPF / ISB / DEG = 34.8 / 49.0 / 16.2 [mol%]. Polycarbonate resin A of copolymerization composition was obtained. The reduced viscosity of this polycarbonate-based resin A was 0.430 dL / g, and the glass transition temperature was 128 ° C.

After vacuum-drying the obtained polycarbonate-based resin A at 80 degreeC for 5 hours, a single screw extruder (Isuzu Kakogi company make, screw diameter 25mm, cylinder set temperature: 220 degreeC), T-die (width 900mm, set temperature) : 220 degreeC), the polycarbonate-type resin film which is 195 micrometers in thickness, and 10 ppm of residual solvent quantity is produced as long film A1 using the film forming apparatus provided with the cooling roll (setting temperature: 120-130 degreeC), and a winding machine. It was.

(Production of long film A2)

The polycarbonate-type resin film (PC film) as long film A2 was produced with the following manufacturing method (solution casting film forming method).

<Dope composition>

100 parts by mass of polycarbonate-based resin A (same as the resin used in the production of long film A1)

Methylene chloride 430 parts by mass

90 parts by mass of methanol

The composition was placed in a sealed container, kept at 80 ° C under pressure, and dissolved completely with stirring to obtain a dope composition.

Subsequently, this dope composition was filtered, cooled, it hold | maintained at 33 degreeC, it casted uniformly on a stainless steel band, and dried at 33 degreeC for 5 minutes. Then, after adjusting drying time at 65 degreeC and peeling on a stainless steel band, drying is complete | finished, conveying with many rolls, and the film thickness is 75 micrometers, and the polycarbonate-type resin film whose residual solvent amount is 110 ppm is a long film. Obtained as A2.

(Production of long film B1)

An alicyclic olefin polymer resin film (COP film) as the long film B1 was produced by the following production method (melt casting film forming method).

In a nitrogen atmosphere, 1.2 parts by mass of 1-hexene, 0.15 parts by mass of dibutyl ether, and 0.30 parts by mass of triisobutyl aluminum were mixed in a reactor at room temperature, mixed with 500 parts by mass of dehydrated cyclohexane, and then maintained at 45 ° C. 20 parts by mass of cyclo [4.3.0.12,5] deck-3,7-diene (dicyclopentadiene, hereinafter abbreviated as DCP), 1,4-methano-1,4,4a, 9a-tetrahydrofluorene (Hereinafter abbreviated as MTF) Norbornene-based monomer mixture comprising 140 parts by mass and 40 parts by mass of 8-methyl-tetracyclo [4.4.0.12,5.17,10] -dodeca-3-ene (hereinafter abbreviated as MTD) And 40 mass parts of tungsten hexachloride (0.7% toluene solution) were continuously added over 2 hours, and it superposed | polymerized. 1.06 mass parts of butylglycidyl ethers and 0.52 mass part of isopropyl alcohols were added to the polymerization solution, the polymerization catalyst was inactivated, and the polymerization reaction was stopped.

Next, 270 parts by mass of cyclohexane is added to 100 parts by mass of the reaction solution containing the obtained ring-opened polymer, and 5 parts by mass of a nickel-alumina catalyst (manufactured by Nikki Shokubai Kasei Co., Ltd.) is added as a hydrogenation catalyst to hydrogen. The mixture was heated to a temperature of 200 ° C. while being pressurized to 5 MPa and stirred, and then reacted for 4 hours to obtain a reaction solution containing 20% of the DCP / MTF / MTD ring-opening polymer hydrogenated polymer.

After removing the hydrogenation catalyst by filtration, a soft polymer (manufactured by Kuraray Co., Ltd .; Septon 2002) and an antioxidant (manufactured by Chiba Specialty Chemicals; Irganox 1010) were added and dissolved in the obtained solution, respectively. (0.1 mass part per 100 mass parts of polymers in all). Subsequently, cyclohexane and other volatile components, which are solvents, were removed from the solution using a cylindrical concentrated dryer (manufactured by Hitachi Seisakusho Co., Ltd.), the hydrogenated polymer was extruded from the extruder into a strand shape in a molten state, and then cooled. Recovered by pelleting. The copolymerization ratio of each norbornene-based monomer in the polymer was calculated by the residual norbornene composition (by gas chromatography) in the solution after polymerization, which was almost equivalent to the charged composition at DCP / MTF / MTD = 10/70/20. It was. As for the weight average molecular weight (Mw) of this ring-opening polymer hydrogenated substance, 31,000, molecular weight distribution (Mw / Mn) were 2.5, the hydrogenation rate was 99.9%, and glass transition temperature Tg was 134 degreeC.

The pellet of the obtained ring-opened polymer hydrogenated substance was dried at 70 degreeC for 2 hours using the hot air dryer which let air flow through, and water was removed. Subsequently, the pellet was melted using a single-screw extruder having a T-die of coat hanger type (manufactured by Mitsubishi Kogyo Co., Ltd .: screw diameter 90 mm, T-tipped part material is tungsten carbide and peeling strength 44N with molten resin). It extrusion-molded and obtained the alicyclic olefin polymer resin film (COP film) whose thickness is 75 micrometers, and the amount of residual solvent is 10 ppm as elongate film B1.

(Production of long film B2)

The dope composition was prepared using the hydrogenated polymer obtained by preparation of elongate film B1 instead of polycarbonate resin A, and it carried out similarly to preparation of elongate film A2 by the solution casting film forming method except having used the prepared dope composition. The alicyclic olefin polymer-based resin film (COP film) having a residual solvent amount of 110 ppm was produced as a long film B2.

(Production of long film C)

The polyethylene naphthalate type resin film (PEN film) as a long film C was produced with the following manufacturing method (melt casting film forming method).

Synthesis of Polyethylenenaphthalate

100 mass parts of 2, 6- naphthalene dicarboxylic acid dimethyl esters, and 60 mass parts of ethylene glycol were transesterified according to a conventional method using 0.03 mass part of cobalt acetate tetrahydrates as a transesterification catalyst. Thereafter, 0.023 parts by mass of trimethyl phosphate was added to substantially terminate the transesterification reaction. Subsequently, 0.024 mass part of antimony trioxide was added, and polycondensation reaction was performed by the normal method under high temperature, high vacuum, and it was 0.62 dL / of intrinsic viscosity (measured at 35 degreeC by phenol / tetrachloroethane mixed solvent (mass ratio 1: 1)). g of polyethylene naphthalate was obtained.

<Production of film>

The pellet of the obtained polyethylene naphthalate was dried at 180 degreeC for 3 hours, and it supplied to the extruder hopper. It melt | dissolved at melt temperature 300 degreeC, and the molten polymer was extruded through the 9.0 mm slit-phase die on the rotary cooling drum of surface temperature 40 degreeC, and the polyethylene naphthalate type resin film of 8 ppm of residual solvent amount was obtained as long film C.

(Production of long film D)

The cellulose ester-type resin film (CE film) as a long film D was produced with the following manufacturing methods (solution casting film forming method).

<Particulate dispersion>

11 parts by mass of fine particles (aerosil R972V Nippon Aerosil Co., Ltd.)

Ethanol 89 parts by mass

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

<Particulate addition liquid>

Based on the following composition, the said fine particle dispersion was added slowly, stirring sufficiently to the dissolution tank containing methylene chloride. Further, dispersion was performed by an attritor so that the particle size of the secondary particles became a predetermined size. This was filtered by FineMet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle addition liquid.

Methylene chloride 99 parts by mass

5 parts by mass of fine particle dispersion

<Main dope liquid>

The main dope liquid of the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. It injected | threw-in stirring the cellulose acetate to the pressure dissolution tank containing a solvent. It was dissolved completely while heating and stirring. This is Azumi Rossi No. of Azumi Rossi Co., Ltd. product. It filtered using 244 and prepared the main dope liquid. In addition, the compound synthesize | combined by the following synthesis examples was used for the sugar ester compound.

<< composition of main dope liquid >>

100 mass parts of cellulose acetate propionate (acetyl group substitution degree 1.39, propionyl group substitution degree 0.50, total substitution degree 1.89)

5.0 parts by mass of a sugar ester compound

1 part by mass of fine particle addition liquid

Methylene chloride 340 parts by mass

Ethanol 64 parts by mass

Synthesis of Sugar Ester Compounds

The sugar ester compound was synthesize | combined by the following processes.

To the four heads of the corbene equipped with a stirring device, a reflux cooler, a thermometer, and a nitrogen gas introduction tube, 34.2 g (0.1 mol) of sucrose, 180.8 g (0.6 mol) of benzoic anhydride, 379.7 g (4.8 mol) of pyridine were added thereto under stirring. The temperature was raised while bubbling nitrogen gas from the nitrogen gas introduction tube, and esterification reaction was performed at 70 ° C for 5 hours.

Next, the inside of the colben was decompressed to 4 × 10 ² Pa or less, and excess pyridine was distilled off at 60 ° C., and then the inside of the benbene was reduced to 1.3 × 10 Pa or less, and the temperature was raised to 120 ° C. to produce benzoic anhydride. Most of the benzoic acid was distilled off.

Finally, the addition of 100g of water to obtain a toluene layer, and washed with water at room temperature for 30 minutes, to obtain a toluene layer, and distilling off toluene under reduced pressure (4 × 10 ² or less Pa), 60 ℃, compound A- A mixture (sugar ester compound) of 1, A-2, A-3, A-4 and A-5 was obtained.

The resulting mixture was analyzed by HPLC and LC-MASS, whereby 1.3% by mass of A-1, 13.4% by mass of A-2, 13.1% by mass of A-3, 31.7% by mass of A-4 and 40.5% of A-5. %. Average substitution degree was 5.5.

<Measurement conditions of HPLC-MS>

1) LC part

Equipment: Nippon Bunko Co., Ltd. column oven (JASCO CO-965), detector (JASCO UV-970-240 nm), pump (JASCO PU-980), deaerator (JASCO DG-980-50)

Column: Inertsil ODS-3 particle diameter of 5 μm 4.6 × 250 mm (manufactured by GE Science Co., Ltd.)

Column temperature: 40 ℃

Flow rate: 1ml / min

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

Injection volume: 3 μl

2) MS part

Device: LCQ DECA (manufactured by Thermo Quest Co., Ltd.)

Ionization Method: Electrospray Ionization (ESI) Method

Spray Voltage: 5㎸

Capillary temperature: 180 ℃

Vaporizer temperature: 450 ℃

Subsequently, the main dope liquid was uniformly cast on the stainless steel belt support using an endless belt casting apparatus. On the stainless steel belt support, the solvent is evaporated until the amount of the residual solvent in the cast (long cast) film becomes 75%, peeled off on the stainless steel belt support, and the drying is terminated while conveying to a large number of rolls, and the film thickness is 75. A cellulose ester-based resin film having a μm and residual solvent amount of 600 ppm was obtained as a long film D.

[Production of inclined stretched film]

(Production of the inclined stretched film 101)

The hoisting body of the long film A1 (PC film, residual solvent amount: 10 ppm) obtained above is set to the film feeding part 2 of the manufacturing apparatus 1 of the diagonal stretched film shown in FIG. The long film A1 was unwound from 2), and it supplied to the extending | stretching part 5, and diagonally stretched in the extending | stretching part 5, and obtained the elongate diagonal stretched film 101 whose film thickness is 45 micrometers. And the diagonal stretched film 101 was conveyed to the film winding-up part 9, and wound up in roll shape. In addition, about the temperature conditions at the time of extending | stretching in the extending | stretching part 5, it selected suitably in the range of (Tg-10) degreeC-(Tg + 30) degreeC of a film.

In addition, in each edge part of the width direction of a long film before diagonal stretch, the force applied to a conveyance direction by each holding | gripping tool Co * Ci is called the same Tr (N), respectively, and the width of a long film during diagonal stretch In each end of the direction, the force exerted on the conveying direction by the holding tool Co on the relatively delaying side and the holding tool Ci on the relatively preceding side is referred to as To (N) and Ti (N), respectively. In the diagonal stretch process in the extending | stretching part 5, the long film was extended in the diagonal direction so that it might become (Ti-Tr) /Tr=1.3 and (Tr-To) /Tr=1.0. In addition, as said force Tr * Ti * To, the drive force of the motor which rotates the said drive roller at the time of driving the chain which conveys holding | gripping tool Co * Ci in a drawing part 5 with a drive roller (control of a motor) Readable on the device).

In addition, the extending | stretching angle of the film in the extending | stretching part 5 was set to 45 degrees. In addition, the said extending | stretching angle refers to the angle (orientation angle) which the in-plane slow axis of a film and the width direction of a film make at the end of a diagonal stretch process. The extending | stretching angle was adjusted by changing the length of a rail, the degree of curvature, etc. in the bending part (extension zone Z2) of the extending part 5.

(Production of the inclined stretched film 102)

In the extending | stretching part 5, elongate film A1 was extended in the diagonal direction (45 degree-direction with respect to the width direction) so that it might become (Ti-Tr) /Tr=2.0 and (Tr-To) /Tr=1.5. Other than that, the diagonal stretched film 102 was produced similarly to preparation of the diagonal stretched film 101. FIG.

(Production of the inclined stretched film 103)

In the extending | stretching part 5, elongate film A1 was extended in the diagonal direction (45-degree direction with respect to the width direction) so that it might become (Ti-Tr) /Tr=3.0 and (Tr-To) /Tr=2.0. Other than that, the diagonal stretched film 103 was produced similarly to preparation of the diagonal stretched film 101. FIG.

(Production of the inclined stretched film 104)

In the extending | stretching part 5, elongate film A1 was extended in the diagonal direction (45-degree direction with respect to the width direction) so that it might become (Ti-Tr) /Tr=3.0 and (Tr-To) /Tr=3.0. In addition, the edge part gripped by the holding | gripping tool Co of the side which is relatively delayed among each edge part of the width direction of elongate film A1 was cooled by spray of cooling wind. At this time, in the width direction of elongate film A1, the edge part gripped by the holding | gripping tool Co of the delay side was cooled so that it might become 10 degreeC lower than the edge part gripped by the holding | gripping tool Ci of a preceding side. Other than that, the diagonal stretched film 104 was produced similarly to preparation of the diagonal stretched film 101. FIG.

(Production of the inclined stretched film 105)

In the extending | stretching part 5, elongate film A1 was extended in the diagonal direction (45-degree direction with respect to the width direction) so that it might become (Ti-Tr) /Tr=3.5 and (Tr-To) /Tr=3.5. In addition, with respect to the width direction of the long film A1, the long film A1 is obliquely stretched so that the slow axis may be oriented at 60 ° larger than the desired orientation angle (here, 45 °), and then the slow axis is oriented at 45 °. Long film A1 was diagonally stretched. Other than that, the diagonal stretched film 105 was produced similarly to preparation of the diagonal stretched film 101. FIG.

(Production of the inclined stretched film 106)

In the extending | stretching part 5, elongate film A1 was extended in the diagonal direction (45-degree direction with respect to the width direction) so that it might become (Ti-Tr) /Tr=4.0 and (Tr-To) /Tr=4.0. In addition, the edge part gripped by the holding | gripping tool Co of the side which is relatively delayed among each edge part of the width direction of elongate film A1 was cooled by spray of cooling wind. At this time, in the width direction of elongate film A1, the edge part gripped by the holding | gripping tool Co of the delay side was cooled so that it might become 10 degreeC lower than the edge part gripped by the holding | gripping tool Ci of a preceding side. Moreover, with respect to the width direction of the long film A1, the long film A1 is diagonally stretched so that the slow axis may be oriented at 60 degrees larger than the desired orientation angle (here, 45 °), and then the slow axis is oriented at 45 °. Long film A1 was diagonally stretched so that it might be. Other than that, the diagonal stretched film 106 was produced similarly to preparation of the diagonal stretched film 101. FIG.

(Production of the inclined stretched film 107)

The diagonally stretched film 107 was produced similarly to preparation of the diagonally stretched film 104 except having performed diagonal stretch using long film A2 (PC film, residual solvent amount: 110 ppm) instead of the long film A1.

(Production of the inclined stretched film 108)

The diagonal stretched film 108 was produced like the manufacture of the diagonal stretched film 103 except having changed the rail pattern in the extending | stretching part 5, and diagonally extending so that the orientation angle might be 75 degrees.

(Production of the inclined stretched film 109)

The diagonal stretched film 109 was produced similarly to preparation of the diagonal stretched film 103 except having changed the rail pattern in the extending | stretching part 5, and diagonally extending so that the orientation angle might be 15 degrees.

(Production of the inclined stretched film 110)

The diagonally stretched film 110 was produced similarly to the preparation of the diagonally stretched film 103 except that diagonally stretched using the long film D (CE film, 600 ppm of residual solvent) instead of the long film A1.

(Production of the inclined stretched film 111)

The diagonal stretched film 111 was produced like the preparation of the diagonal stretched film 110 except having changed the rail pattern in the extending | stretching part 5, and diagonally stretched so that the orientation angle might be 75 degrees.

(Production of the inclined stretched film 112)

The diagonally stretched film 112 was produced like the preparation of the diagonally stretched film 103 except having performed diagonal stretch using long film B2 (COP film, 110 ppm of residual solvent amount) instead of the long film A1.

(Production of the inclined stretched film 113)

The diagonally stretched film 113 was produced like the manufacture of the diagonally stretched film 103 except having performed diagonal stretch using long film B1 (COP film, 10 ppm of residual solvent amount) instead of the long film A1.

(Production of the inclined stretched film 114)

The diagonally stretched film 114 was produced like the manufacture of the diagonally stretched film 103 except having performed diagonal stretch using long film C (PEN film, 8 ppm of residual solvent amount) instead of the long film A1.

(Production of the inclined stretched film 115)

In the extending | stretching part 5, elongate film A1 was extended in the diagonal direction (45-degree direction with respect to the width direction) so that it might become (Ti-Tr) /Tr=2.0 and (Tr-To) /Tr=2.0. Other than that, the diagonal stretched film 115 was produced similarly to preparation of the diagonal stretched film 101. FIG.

(Production of the inclined stretched film 116)

In the extending | stretching part 5, elongate film A1 was extended in the diagonal direction (45-degree direction with respect to the width direction) so that it might become (Ti-Tr) /Tr=4.0 and (Tr-To) /Tr=5.5. Other than that, the diagonal stretched film 116 was produced similarly to preparation of the diagonal stretched film 101. FIG.

(Production of the inclined stretched film 117)

In the extending | stretching part 5, elongate film A1 was extended in the diagonal direction (45-degree direction with respect to the width direction) so that it might become (Ti-Tr) /Tr=1.7 and (Tr-To) /Tr=1.5. Other than that, the diagonal stretched film 117 was produced similarly to preparation of the diagonal stretched film 101. FIG.

[Measurement of dimension change rate ΔD _F , ΔD _L ]

Each of the width direction center part C of the diagonal stretched film 101-117 produced above, one edge part E1 (end part hold | gripping by a leading side holding | gripping tool), and the other end E2 (end part gripped by a delaying side holding | gripping tool) In the above, two marks arranged in the fast axis direction are marked, the distance a1 (mm) between the two points is measured with a ruler, or the like, and two marks arranged in the slow axis direction are marked, and the distance between the two points is measured. b1 (mm) was measured by the ruler. The slow axis direction is the stretching direction (orientation angle direction), and the fast axis direction is a direction perpendicular to the slow axis direction in the film plane, so that the slow axis direction and the fast axis direction are inclined on the inclined stretched films 101 to 117. It is easy to specify.

Next, after leaving the inclined stretched films 101 to 117 at 90 ° C. for 120 hours, in each of the width direction center part C, one end E1, and the other end E2 of each film, two points are arranged in the fast axis direction. The distance a2 (mm) of the liver was measured with a ruler or the like, and the distance b2 (mm) between two points arranged in the slow axis direction was measured with a ruler or the like. And the dimensional change rate (DELTA) D _F (%) of the fast-axis direction and the dimensional change rate (DELTA) D _L (%) of the slow-axis direction were computed by the following formulas for every center part C and edges E1 * E2 of a film.

ΔD _F = {(a2-a1) / a1} × 100

ΔD _L = {(b2-b1) / b1} × 100

Table 1 shows various parameters related to the inclined stretched films 101 to 117, including the dimensional change rate ΔD _F · ΔD _L. In Table 1, the widthwise central portion of the film C, shows a dimensional change rate ΔD _F in the fast axis direction of the end E1 · E2, as ΔD _{-C F, F} ΔD _{-E1, -E2} ΔD _F, the central part C, a dimensional change rate ΔD _L in the slow axis direction of the end E1 · E2, expressed as _{ΔD L -C, ΔD L -E1,} ΔD L -E2.

[Production of Polarizing Plate]

(Production of Polarizing Plate 201)

<Making Polarizers>

Boric acid and potassium iodide were subjected to a dyeing process and 2.5 times stretching treatment by immersing the long polyvinyl alcohol film having a thickness of 60 μm continuously through a guide roll in a dye bath (30 ° C.) of iodine and potassium iodide. In the acidic bath (60 degreeC) to which the addition was carried out, the extending | stretching process and crosslinking process which multiply a total 5 times are performed, and the obtained 12 micrometers iodine-PVA system polarizer is dried in 50 degreeC for 30 minutes in a dryer, and the moisture content is 4.9%. Polarizer was obtained.

<Preparation of UV-curable adhesive>

Each of the following components was mixed to prepare a liquid ultraviolet curable adhesive (UV adhesive).

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate

40 parts by mass

60 parts by mass of bisphenol A type epoxy resin

4.0 mass parts of diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoro antimonate (cationic polymerization initiator)

<Junction>

After performing the corona treatment on the bonding surface of the diagonal stretched film 101, the prepared ultraviolet curable adhesive agent was coated by 3 micrometers in thickness with the coating apparatus provided with the chamber doctor. Furthermore, after corona treatment was performed to the bonding surface of the protective film 1 (Konica Minolta Tack KC4UY, thickness 40 micrometers, Konica Minolta Co., Ltd. product), the said ultraviolet curable adhesive agent was similarly coated by thickness of 3 micrometers.

Then, immediately afterwards, the diagonal stretched film 101 was bonded to the single side | surface of the polarizer prepared above, and the protective film 1 was bonded to the other side with the bonding roll through the coating surface of an ultraviolet curable adhesive, respectively. At this time, both were bonded so that the width direction of the diagonally stretched film 101 and the absorption axis (or transmission axis) of the polarizer coincide (the angle between the slow axis of the diagonally stretched film 101 and the absorption axis of the polarizer is 45 °. ). Thereafter, the metal halide lamp is turned on at a line speed of 20 m / min, and ultraviolet rays are irradiated from the inclined stretched film 101 side so as to be 320 mJ / cm 2 at an accumulated light amount at a wavelength of 280 to 320 nm to cure the adhesive on both sides. The polarizing plate 201 was produced. Moreover, since manufacture of the polarizing plate 201 is performed by the roll-to-roll system, finally, the elongate polarizing plate 201 was cut | disconnected along the width direction, and the sheet-like polarizing plate 201 was obtained.

(Production of Polarizing Plates 202 to 217)

Except having changed the diagonal stretched film 101 into the diagonal stretched films 102-117, it carried out similarly to manufacture of the polarizing plate 201, and produced the polarizing plates 202-217.

(Production of Polarizing Plate 218)

A polarizing plate 218 was produced in the same manner as in the preparation of the polarizing plate 203, except that the inclined stretched film 103, the polarizer, the polarizer, and the protective film 1 were each bonded using a water glue (polyvinyl alcohol adhesive). . In addition, the polarizing plate 218 was dried for 2 minutes at 80 degreeC for the purpose of accelerating hardening of an adhesive agent.

(Production of Polarizing Plate 219)

Except having used the protective film 2 instead of the protective film 1, it carried out similarly to manufacture of the polarizing plate 203, and produced the polarizing plate 219. In addition, the protective film 2 is produced as follows.

<Production of Protective Film 2>

`` Preparation of particulate dispersion ''

11.3 parts by mass of fine particles (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.) and 84 parts by mass of ethanol were stirred and mixed with a dissolver for 50 minutes, and then dispersed in a manton-gaulin to prepare a fine particle dispersion.

Next, 5 mass parts of fine particle dispersions were slowly added to the fully stirred dichloromethane (100 mass parts) in a dissolution tank. In addition, dispersion was performed with an attritor so that the particle size of the secondary particles became a predetermined size. This was filtered by FineMet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle addition liquid.

<< preparation of dope >>

Main dope of the following composition was prepared. First, dichloromethane and ethanol were added to the pressure dissolution tank. And cycloolefin resin A (antioxidant addition complete), a ultraviolet absorber, and microparticles | fine-particles addition liquid were thrown into the pressure dissolution tank, stirring. It melt | dissolves completely, heating this, stirring, and Azumi Rossi No. of Azumi Rossi Co., Ltd. make. It filtered using 244 and prepared the main dope.

100 mass parts of cycloolefin resin A

Antioxidant (0.5 parts by mass of IRGNOX1010 (manufactured by BASF Japan)

200 parts by mass of dichloromethane

10 parts by mass of ethanol

3 mass parts of ultraviolet absorbers (tinuvin 928 (BASF Japan Co., Ltd. product))

3 parts by mass of fine particle addition liquid

In addition, cycloolefin resin A is a thing of the following structure.

Subsequently, the main dope was uniformly cast on the stainless steel belt support body at the temperature of 31 degreeC, and 1800 mm width using an endless belt casting apparatus. The temperature of the stainless steel belt was controlled at 28 ° C. The conveyance speed of the stainless steel belt was 20 m / min.

On the stainless steel belt support body, the solvent was evaporated until the residual solvent amount in the cast film became 30%. Next, the cast film was peeled off on the stainless steel belt support at a peel tension of 128 N / m. The exfoliated cast film was stretched 2.2 times in the width direction under the condition of 160 ° C. The residual solvent at the time of extending | stretching start was 5 mass%. Subsequently, drying was complete | finished while conveying a dry zone with many rollers, the edge part inserted with the tenter clip was slit by the laser cutter, it was wound up after that, and the protective film 2 of 40 micrometers of film thicknesses was obtained.

[evaluation]

(The amount of curl)

The produced polarizing plates 201-219 were cut out to the magnitude | size of 30 cm x 30 cm, and the polarizing plate sample was obtained. And the obtained polarizing plate sample was arrange | positioned so that the surface of the convex side of this sample may face a stage surface. And the height from the stage surface of the four corner parts a-d of the polarizing plate sample was measured, respectively, and the curl amount C was calculated | required by the following relational formula.

C = [(Ha + Hb + Hc + Hd) / 4] / L

only,

Ha: Height (mm) from the stage surface of the corner part a

Hb: Height (mm) from the stage surface of the corner part b

Hc: Height (mm) from the stage surface of the corner part c

Hd: Height (mm) from the stage surface of the corner part d

L: length of polarizing plate sample (= 300 mm)

to be. And the curl amount of the polarizing plate was evaluated based on the following evaluation criteria.

"Evaluation standard"

◎: Curl amount C is 0% or more but less than 3%

○: curl amount C is 3% or more but less than 6%

△: curl amount C is 6% or more but less than 10%

X: Curling amount C is 10% or more

(Adhesiveness)

In the edge parts of the produced polarizing plates 201 to 219, the blade edge of the cutter was inserted between the polarizer and the optical film (inclined stretched film). And in the said insertion part, the polarizer and the optical film were gripped, each was tension | pulled in the opposite direction, and the adhesiveness was evaluated based on the following evaluation criteria.

"Evaluation standard"

(Circle): A polarizer or an optical film breaks and cannot peel, and adhesiveness is favorable.

(Triangle | delta): Although it peeled partly between a polarizer and an optical film, it is a range without a problem.

X: It peels all between a polarizer and an optical film, and adhesiveness is bad.

(Light leakage)

The polarizing plates 201 to 219 obtained above were cut | disconnected to predetermined | prescribed magnitude | size, and were bonded to the visual recognition side of organic electroluminescent panel (LG Display company brand name 15EL9500) through acrylic adhesive, and organic electroluminescent display apparatuses 301-319 were produced. . At this time, in the polarizing plates 201 to 219, the diagonally stretched film was arrange | positioned so that it might become the organic electroluminescent panel side with respect to a polarizer. In addition, the said organic electroluminescent panel used for evaluation was used after peeling off the antireflection film bonded to the surface beforehand.

And the organic electroluminescent panel was displayed in black, light leakage by the external light reflection at that time was visually confirmed, and light leakage was evaluated based on the following evaluation criteria.

"Evaluation standard"

○: no light leakage

(Triangle | delta): Although light leakage is seen a little, there is no problem in practical use

X: Light leakage is seen and there is a problem in practical use

(Visibility)

In a 21.5-inch liquid crystal display device (IPS226V-PN, manufactured by LG Electronics Japan Co., Ltd.), the polarizing plate on the observer's side (viewing side, opposite to the backlight) is peeled out of two polarizing plates provided with a liquid crystal layer. The above-mentioned polarizing plates 201 to 219 are made to have the inclined stretched film to the viewing side (the opposite side to the liquid crystal cell) with respect to the polarizer, and to be bonded to the glass of the liquid crystal cell with an optical adhesive to form a liquid crystal display device. 419). At this time, the viewing side polarizing plate was arrange | positioned so that the transmission axis of the visual side polarizing plate and the transmission axis of the polarizing plate of a backlight side may orthogonally cross.

An image was displayed on the obtained liquid crystal display devices 401-419, it observed through polarized sunglasses, and evaluated visibility based on the following evaluation criteria.

"Evaluation standard"

(Double-circle): There is no distortion in a display image, and visibility is very favorable.

(Circle): There is little distortion in a display image, and visibility is favorable.

(Triangle | delta): Although there exists some distortion in a display image, there is no problem in actual use.

X: There is distortion in a display image, and visibility is bad.

Table 2 shows the results of various evaluations of the polarizing plates 201 to 219.

From Table 1 and Table 2, in each of the center part C of the width direction of a film, and the edge part E1, E2, the dimensional change rate (DELTA) D _F of a fast-axis direction and the dimensional change rate (DELTA) D _L of a slow-axis direction,

0% ≤ΔD _F <0.5%

ΔD _L <0%

In the polarizing plate using the inclined stretched film which satisfy | fills and the amount of residual solvent is 60 ppm (middle value of 110 ppm and 10 ppm) or less, favorable result is obtained in both curl amount and adhesiveness (refer to the inclined stretched film of the Example of a table | surface and a polarizing plate) ). This does not shrink in the fast axis direction even if the inclined stretched film shrinks in the slow axis direction under a high temperature environment, so that the shrinkage of the entire film can be suppressed, and at the time of adhesion between the inclined stretched film and the polarizer requiring a high temperature. Edo (in the case of using an ultraviolet curable adhesive) is considered to be because the shrinkage of the entire film can be suppressed at the time of ultraviolet irradiation, and in the case of heating to accelerate the curing when water pool is used. As a result, in the organic electroluminescence display using the polarizing plate of an Example, reflection (light leakage) of external light becomes the range which does not have a problem in actual use, and in the liquid crystal display device corresponding to polarized sunglasses using the polarizing plate of an Example, a distortion of a display image The fall of the visibility by this has become the range which does not have a problem in actual use.

In addition, solvent casting and film formation method of the one long film stretching oblique stretching the film (107, 110 to 112), the fast axis dimensional change ΔD _F are all part (負) in the direction film formation, the contraction in the fast axis direction at a high temperature environment It is a characteristic to say. This is considered to be for the following reasons. In the solution casting film forming method, since the solvent is used for film formation of the film, the resin density of the film formed is low and extends in both directions with the slow axis direction and the fast axis direction close to the conveyance direction at the time of diagonal stretching. easy. For this reason, after the diagonal stretch, the tensile stress remains at least in the fast axis direction, and the tensile stress is relaxed under a high temperature environment, and consequently shrinks in the fast axis direction.

Therefore, in this respect, to the dimensional change rate ΔD _F in the fast axis direction to zero or more, solution casting film forming film-forming a long film by using a film forming method other than the method, and the long film is desirable to tilt the stretching, in particular From the result of the diagonal stretched film 102 etc., it can be said that it is preferable to diagonally stretch the long film formed into a film using the melt casting film forming method. In other words, in the long film formed using the melt casting film forming method, since the residual solvent amount is 60 ppm or less (preferably 10 ppm or less), the elongate film having a residual solvent amount of 60 ppm or less (preferably 10 ppm or less) is obliquely stretched. is, the fast axis _F of the dimensional change rate ΔD direction may be desirable when producing a stretched film that is inclined more than zero.

Moreover, in the diagonal stretched film 101 extended | stretched on condition of (Ti-Tr) /Tr=1.3 and (Tr-To) /Tr=1.0 at the time of diagonal stretch, the long film A1 formed into a film by the melt casting film forming method is carried out. Despite the oblique stretching, the dimensional change rate ΔD _F in the fast axis direction is negative, and has a characteristic of shrinking in the fast axis direction under a high temperature environment. This is considered to be for the following reasons. That is, at the time of diagonal stretch, since the force change amount (increase amount) of the conveyance direction in the edge part of the preceding side of a film, and the force change amount (reduced amount) of the conveyance direction in the edge part of a delay side are both small, the direction of the diagonal stretch (ground surface) Axial direction), while in the conveying direction, the film is in a state in which the film shrinks or resists the tension during conveyance or is in balance with the tension, so that the film does not grow or shrink. Tensile stress remains in the fast axis direction close to the direction. Then, the tensile stress is relaxed under a high temperature environment, thereby shrinking in the fast axis direction.

Therefore, from the result of the diagonal stretched films 102-117 and the polarizing plates 202-217, in the diagonal stretch process in the extending | stretching part 5,

(Ti-Tr) /Tr≥1.7

(Tr-To) /Tr≥1.5

It can be said that it is preferable to diagonally stretch the long film (film-formed by the melt casting film forming method) whose residual solvent amount is 60 ppm or less so that it may satisfy.

In addition, in the polarizing plates 204 to 206 using the inclined stretched films 104 to 106, the curl amount and the adhesiveness are higher than those of the other polarizing plates (for example, the polarizing plate 203). This is because, in the production of the inclined stretched films 104 to 106, the width end is cooled in the inclined stretching step, whereby a large shrinkage stress can be retained at the width end in the fast axis direction, and at the time of adhesion with the polarizer. It is considered that the above-mentioned shrinkage stress is alleviated under a high-temperature environment, so that the inclined stretched film is expanded in the fast axis direction, whereby the dimensional change (shrinkage) of the entire film can be further suppressed even when shrinking in the slow axis direction. In particular, in the production of the inclined stretched film 106, since the two-stage stretching is performed in addition to the end cooling in the inclined stretching process, a larger shrinkage stress can be retained in the fast axis direction at the width end, and thus the polarizer Dimensional change (shrinkage) of the whole film in the high temperature environment at the time of adhesion | attachment with can be suppressed further. For this reason, it is thought that the highest evaluation was obtained about curl amount and adhesiveness.

In addition, (ΔD _{F -E1 -E2} + ΔD _F) / 2> a polarizing plate using the stretched film as inclined nation conditions of ΔD _{F -C} (e.g. a polarizing plate 202), the oblique stretching does not satisfy the condition Compared with the polarizing plate (for example, polarizing plates 215 * 217) using a film, evaluation of curl amount and adhesiveness is at least one grade higher. In consideration of the nonuniform curing shrinkage at each position in the width direction of the adhesive, the difference in the dimensional change rate (expansion amount) in the fast axis direction from the width direction center portion and the end portion of the inclined stretched film is obtained. The curl of the polarizing plate due to the large curing shrinkage of the polarizing plate is suppressed by the small expansion in the fast axis direction of the diagonally stretched film, and at the width end, the curl of the polarizing plate due to the large expansion of the fastening axis direction of the diagonally stretched film is small curing shrinkage of the adhesive. It is considered that this is because the curl is reliably suppressed in the entire width direction of the polarizing plate.

The optical film of this invention can be used, for example for the circularly-polarizing plate for preventing external light reflection of an organic electroluminescent display, and the polarizing plate of the liquid crystal display device corresponding to polarized sunglasses.

50: polarizer
52: polarizer
53: retardation film (optical film)
100: organic EL display device
101: organic EL element (display cell)
301: polarizer
311: lambda / 4 phase difference film (optical film)
313: polarizer
400: liquid crystal display
401: liquid crystal cell (display cell)
402: polarizer
411: polarizer
413: lambda / 4 phase difference film (optical film)
Co: grip
Ci: grip

Claims (14)

An optical film in which the slow axis is inclined 10 to 80 ° with respect to one side of the film appearance within the film plane,
When the optical film have been referred to as the fast axis direction and the rate of dimensional change of the slow axis direction in the before and after left to stand at 90 ℃ 120 hours, respectively ΔD _F (%) and ΔD _L (%), the central portion of the along the one side direction, And at both ends,
0% ≤ΔD _F <0.5%
ΔD _L <0%
Satisfying,
The amount of residual solvent is 60 ppm or less, The optical film characterized by the above-mentioned. The method of claim 1,
The amount of residual solvent is 10 ppm or less, The optical film characterized by the above-mentioned. The method according to claim 1 or 2,
In the said optical film, as distance between two points arrange | positioned in a fast axis direction, the distance before leaving this optical film for 120 hours at 120 degreeC, and after leaving it is called a1 (mm) and a2 (mm), respectively,
In the said optical film, as distance between two points arrange | positioned in a slow axis direction, when the optical film is left to stand at 90 degreeC for 120 hours, and the distance after leaving it is set to b1 (mm) and b2 (mm), respectively. ,
ΔD _F = {(a2-a1) / a1} × 100
ΔD _L = {(b2-b1) / b1} × 100
It is an optical film characterized by the above-mentioned. The method according to claim 1 or 2,
In the center part of the direction along one said side, the rate of dimensional change in the fast-axis direction before and after leaving this optical film at 90 degreeC for 120 hours is called (DELTA) D _FC (%),
In one end of the direction along the said one side, the rate of dimensional change in the fast-axis direction before and after leaving this optical film at 120 degreeC for 120 hours is called (DELTA) D _F-E1 (%),
In the other end part of the direction along the said one side, when the dimension change rate of the up-axis direction before and after leaving this optical film to stand at 90 degreeC for 120 hours is set to (DELTA) D _F-E2 (%),
(ΔD _F-E1 + ΔD _F-E2 ) / 2> ΔD _FC
To satisfy more, the optical film. The method according to claim 1 or 2,
The optical film is a long shape,
The direction along the said one side is the width direction perpendicular | vertical to the longitudinal direction in the film surface of the said optical film, The optical film characterized by the above-mentioned. It includes the optical film of Claim 1 or 2, and a polarizer,
The said optical film is located in the one side with respect to the said polarizer so that a slow axis may intersect the absorption axis of the said polarizer in a film plane. The polarizing plate of Claim 6, and a display cell are included,
The polarizing plate is located on the viewing side with respect to the display cell. The method of claim 7, wherein
The said optical film of the said polarizing plate is located in the said display cell side with respect to the said polarizer, The display apparatus characterized by the above-mentioned. The method of claim 8,
The display cell is an organic electroluminescent element, characterized in that the display device. The method of claim 7, wherein
The said optical film of the said polarizing plate is located in the opposite side to the said display cell with respect to the said polarizer, The display apparatus characterized by the above-mentioned. The method of claim 10,
The display cell is a liquid crystal cell, characterized in that the display device. As a manufacturing method of the optical film of Claim 1 or 2,
The long film is conveyed by holding both ends in the width direction of the long film with a pair of grippers, leading one gripper relative to the other gripper, and bending and conveying the long film in the film plane. Extending | stretching to the diagonal direction with respect to, and obtaining the diagonal stretched film which comprises the said optical film, Comprising:
In each end part of the width direction of the said elongate film, the force applied to a conveyance direction by each holding | gripping tool is called same Tr (N), respectively, before diagonal stretch,
During the diagonal stretching, at each end of the elongated film in the width direction, the force exerted on the conveying direction by the gripper on the relatively retarding side and the gripper on the relatively preceding side is respectively applied to To (N) and Ti. When we say (N),
In the oblique stretching step,
(Ti-Tr) /Tr≥1.7
(Tr-To) /Tr≥1.5
The long film is stretched in the oblique direction so as to satisfy the above, The manufacturing method of an optical film. The method of claim 12,
In the said diagonal stretch process, the edge part gripped by the holding | gripping tool of the side which retards relatively is among each edge part of the width direction of the said long film, The manufacturing method of the optical film characterized by the above-mentioned. The method of claim 12,
In the oblique stretching step, the elongated film is obliquely stretched so that the slow axis is aligned at an orientation angle larger than the desired orientation angle with respect to the width direction of the elongated film, and then the slow axis is aligned at the desired orientation angle. And diagonally stretching the said long film, The manufacturing method of the optical film characterized by the above-mentioned.

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