JP2016143046A - Lateral electric field mode liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lateral electric field mode liquid crystal display device that achieves a thin and lightweight device and has excellent durability against changes in temperature and humidity while having a wide viewing angle.SOLUTION: The lateral electric field mode liquid crystal display device has a cover glass 2, a first polarizing plate 3, a lateral electric field mode liquid crystal cell 4, a second polarizing plate 5, and a backlight 6, in which the first polarizing plate 3 has a polarizing plate protective film 3a, a first polarizer 3b, and a film 3c, and the second polarizing plate has a polarizing plate protective film 5a, a second polarizer 5b and a film 5c. The cover glass 2 has a thickness of 0.1 to 0.3 mm; the first polarizer 3b and the second polarizer 5b have a film thickness of 1 to 15 μm; the polarizing plate protective film 3a and the polarizing plate protective film 5a have a shrinkage rate of 0.01 to 0.50%; and at least one of the films 3c, 5c is a retardation film and the other is an isotropic film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a horizontal electric field mode type liquid crystal display device.

  In recent years, liquid crystal display devices have been steadily reduced in thickness and weight, and this tendency is particularly noticeable when used for portable devices such as tablet display devices and smartphones. Generally, a cover glass is provided on the viewing side of the liquid crystal display device. However, the cover glass is also becoming thinner and lighter, and a 0.2 mm thick one has been put into practical use.

  Here, as a method of the liquid crystal display device, a so-called TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type, and the like are well known. In particular, IPS (In Plane Switching) type liquid crystal display devices (hereinafter also simply referred to as “IPS type liquid crystal display devices”) are widely used in portable devices. The IPS liquid crystal display device has an advantage of excellent black display performance because liquid crystal molecules contained in the liquid crystal layer are aligned in parallel with the surfaces of the pair of substrates during black display. Further, the IPS liquid crystal display device has an advantage that a certain high viewing angle can be secured without using a so-called retardation film. On the other hand, due to the optical characteristics of the liquid crystal cell provided in the IPS liquid crystal display device, there is a problem that light leakage occurs when the screen is viewed from an oblique direction, and the contrast of the display image is lowered.

  As a means for solving such a problem, it is known that optical compensation is suitable using a retardation film having a large absolute value of in-plane retardation and a small absolute value of thickness direction retardation. Such a retardation film has a cellulose acylate containing a cellulose acylate having a substitution degree of aromatic acyl groups of 0.35 or more and a substitution degree of aromatic acyl groups at 2, 3, 6 positions satisfying a specific relationship. It is disclosed that it is realized by a rate film (see, for example, Patent Document 1).

JP 2009-235374 A

  However, according to the IPS type lateral electric field mode type liquid crystal display device using the retardation film described in Patent Document 1, the present inventors have realized that the viewing angle is enlarged when the cover glass is thinned. Although it was possible, it was found that display unevenness occurred when the temperature and humidity environment changed.

  The present invention has been made in view of the above problems, and provides a horizontal electric field mode type liquid crystal display device that is thin and lightweight, has a wide viewing angle, and is excellent in durability against changes in temperature and humidity. The purpose is that.

  The above-described problems of the present invention are solved by the following means.

From the display surface side, in the horizontal electric field mode type liquid crystal display device having the cover glass, the first polarizing plate, the horizontal electric field mode type liquid crystal cell, the second polarizing plate and the backlight in this order,
The first polarizing plate has a polarizing plate protective film F1, a first polarizer and a film F2 in this order from the display surface side.
The second polarizing plate has a polarizing plate protective film F4, a second polarizer and a film F3 in this order from the backlight side.
The cover glass has a thickness of 0.1 to 0.3 mm,
The film thickness of said 1st polarizer and said 2nd polarizer is 1-15 micrometers,
The polarizing plate protective film F1 and the polarizing plate protective film F4 have a shrinkage ratio measured by the following method A of 0.01 to 0.50%,
At least one of the film F2 and the film F3 is a retardation film that satisfies the following conditions (1) to (3):
The film F2 and the film F3 that is not the retardation film are isotropic films that satisfy the following conditions (4) and (5):
(1) A cellulose acylate film containing as a main component a cellulose acylate having an aromatic acyl group;
(2) In an environment of 23 ° C. and 55% RH, the in-plane retardation R0 represented by the following formula (I) is 100 to 270 nm with respect to light having a wavelength of 590 nm, and is represented by the following formula (II). Thickness direction retardation Rth is -30 to 30 nm;
(3) The shrinkage percentage measured by the following method B is 0.10 to 1.00%;
(4) In an environment of 23 ° C. and 55% RH, the in-plane retardation R0 represented by the following formula (I) is 0 to 5 nm with respect to light having a wavelength of 590 nm, and is represented by the following formula (II). The thickness direction retardation Rth is -10 to 10 nm;
(5) The shrinkage percentage measured by the following method A is 0.01 to 1.00%;
Formula (I) R0 = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(However, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the film, ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film, nz represents the refractive index in the thickness direction z of the film, and d (nm) represents the thickness of the film).

[Method A]
The film viewed from the position in the polarizing plate in a 90% relative humidity 90% environment for about 100 hours, parallel to the absorption axis direction of the polarizer, the direction orthogonal to the absorption axis direction of the polarizer, the absorption axis of the polarizer Measure the shrinkage in 4 directions, 45 ° from the direction and 135 ° from the absorption axis direction of the polarizer, and set the largest value as the shrinkage.

[Method B]
Measure the shrinkage rate in the two directions of the slow axis direction and the direction perpendicular to the slow axis direction of the retardation film before and after 100 hours of aging at 80 ° C. and 90% relative humidity. The larger value is the shrinkage rate. To do.

  According to the present invention, it is possible to provide a lateral electric field mode type liquid crystal display device that realizes a reduction in thickness and weight, has a wide viewing angle, and is excellent in durability against changes in temperature and humidity.

The schematic diagram of the horizontal electric field mode type liquid crystal display device which concerns on one form of this invention is represented. The schematic diagram of the liquid crystal element pixel area | region of the IPS type | mold liquid crystal cell used for the horizontal electric field mode type liquid crystal display device which concerns on one form of this invention is represented.

  One embodiment of the present invention is a horizontal electric field mode liquid crystal display device having a cover glass, a first polarizing plate, a horizontal electric field mode type liquid crystal cell, a second polarizing plate and a backlight in this order from the display surface side. The first polarizing plate has a polarizing plate protective film F1, a first polarizer and a film F2 in this order from the display surface side, and the second polarizing plate is a polarizing plate from the backlight side. The protective film F4, the second polarizer, and the film F3 are provided in this order, and the cover glass has a thickness of 0.1 to 0.3 mm. The first polarizer and the second polarizer The film thickness is 1 to 15 μm, and the polarizing plate protective film F1 and the polarizing plate protective film F4 have a shrinkage ratio measured by the following method A of 0.01 to 0.50%, and the film F2, And the film F3 At least one is a retardation film that satisfies the following conditions (1) to (3), and the film F2 and the film F3 that is not the retardation film satisfy the following conditions (4) and (5): It is a transverse electric field mode type liquid crystal display device which is an isotropic film satisfying the above.

(1) A cellulose acylate film containing as a main component a cellulose acylate having an aromatic acyl group;
(2) In an environment of 23 ° C. and 55% RH, the in-plane retardation R0 represented by the following formula (I) is 100 to 270 nm with respect to light having a wavelength of 590 nm, and is represented by the following formula (II). Thickness direction retardation Rth is -30 to 30 nm;
(3) The shrinkage percentage measured by the following method B is 0.10 to 1.00%;
(4) In an environment of 23 ° C. and 55% RH, the in-plane retardation R0 represented by the following formula (I) is 0 to 5 nm with respect to light having a wavelength of 590 nm, and is represented by the following formula (II). The thickness direction retardation Rth is -10 to 10 nm;
(5) The shrinkage percentage measured by the following method A is 0.01 to 1.00%;
Formula (I) R0 = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(However, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the film, ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film, nz represents the refractive index in the thickness direction z of the film, and d (nm) represents the thickness of the film).

[Method A]
The film viewed from the position in the polarizing plate in a 90% relative humidity 90% environment for about 100 hours, parallel to the absorption axis direction of the polarizer, the direction orthogonal to the absorption axis direction of the polarizer, the absorption axis of the polarizer Measure the shrinkage in 4 directions, 45 ° from the direction and 135 ° from the absorption axis direction of the polarizer, and set the largest value as the shrinkage.

[Method B]
Measure the shrinkage rate in the two directions of the slow axis direction and the direction perpendicular to the slow axis direction of the retardation film before and after 100 hours of aging at 80 ° C. and 90% relative humidity. The larger value is the shrinkage rate. To do.

  According to the lateral electric field mode type liquid crystal display device according to one embodiment of the present invention having such a configuration, the thinning and the weight reduction are realized, and the durability against a change in temperature and humidity is improved while having a wide viewing angle. sell.

  Here, first, the present inventors, in the prior art, about the cause of display unevenness when the temperature and humidity environment changes in a liquid crystal display device with a thin cover glass, a polarizer constituting a polarizing plate, a retardation film It is presumed that the warping of the panel due to the shrinkage of the polarizing plate protective film is a fundamental cause.

  That is, as a general polarizer, a polyvinyl alcohol polarizer is used. However, in this polyvinyl alcohol polarizer, it contracts greatly in the stretching direction (orientation direction) due to long-term use in a high-temperature and high-humidity environment. large. Moreover, although the retardation film described in Patent Document 1 is a cellulose acylate film containing a cellulose acylate having an aromatic acyl group as a main component, this film is not hydrophobic and is stretched, Similarly, the shrinkage rate in the stretching direction (main chain orientation direction) is large, and the shrinkage force is also large. Here, when the thickness of the cover glass is reduced, it becomes difficult for the panel in the liquid crystal display device to maintain the shape of the panel against the contracting force generated during long-term use in a high-temperature and high-humidity environment, and warpage occurs. As a result of the warpage of the panel, the panel and the backlight sheet come into contact with each other. As a result of such contact, the contact portion between the panel and the backlight sheet becomes difficult to follow ambient temperature and humidity changes, particularly humidity change, and the non-contact portion between the panel and the backlight sheet becomes easy to follow humidity changes. . Moreover, since only the contact portion is heated by the heat of the backlight, the environments of the contact portion and the non-contact portion are different. And in the state which has the contact part and non-contact part of such a panel and a backlight sheet, when the surrounding temperature / humidity change arises, the phase difference film in a panel originates in the moisture content difference of both parts. The in-plane retardation value and the thickness direction retardation value are different. Further, in the polarizer and the retardation film, a difference in shrinkage due to such a difference in water content between the contact portion and the non-contact portion occurs, and the orientation of the retardation film is disturbed by the generation of stress at the interface. It is presumed that the phenomenon due to the warp of the panel as described above generally causes display unevenness.

  As a mechanism by which the above problem is improved by the transverse electric field mode type liquid crystal display device according to one embodiment of the present invention, the inventors set the film thickness of the polarizer to 1 to 15 μm, the retardation film, and if necessary Isotropic film used as well as polarizing plate protective film by reducing the shrinkage rate under high temperature and high humidity, polarizer constituting the polarizing plate, retardation film and isotropic film used as necessary, In addition, it is presumed that the contraction force of each polarizing plate protective film is reduced, and the occurrence of warpage of the panel can be suppressed even when the cover glass is as thin as 0.1 to 0.3 mm. Note that the above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention.

  A horizontal electric field mode type liquid crystal display device 1 according to an embodiment of the present invention includes a cover glass 2, a first polarizing plate 3, a horizontal electric field mode type liquid crystal cell 4, a first display screen side (hereinafter also referred to as a viewing side). The second polarizing plate 5 and the backlight 6 are arranged in this order. Here, the 1st polarizing plate 3 has the 1st polarizer 3b, polarizing plate protective film F1 3a is provided on the visual recognition side rather than the 1st polarizer 3b, rather than the 1st polarizer 3b. A film F2 3c is provided on the backlight 6 side (the side opposite to the viewing side). The second polarizing plate 5 has a second polarizer 5b. The film F3 5c is closer to the viewing side than the second polarizer 5b, and the backlight 6 side is closer to the first polarizer 5b ( A polarizing plate protective film F4 5a is provided on the side opposite to the viewing side.

  In addition, at least one of the film F2 and the film F3 is a retardation film that satisfies the specific condition, and the one that is not the retardation film of the film F2 and the film F3 is an isotropic film that satisfies the specific condition.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and other members known in the art (for example, a touch panel, etc.) may be included. Hereinafter, the components of the horizontal electric field mode type liquid crystal display device will be described in more detail.

[cover glass]
The cover glass is a protective glass used on the front surface of the liquid crystal display device.

  By providing the cover glass, irregular reflection due to the unevenness of the surface of the conventional polarizing plate protective film is reduced, and it is possible to reproduce a color with high contrast and sharpness. Moreover, since the discoloration which generate | occur | produces when the surface of a liquid crystal display device is pushed with a finger | toe can be eliminated, it is preferably used especially for the liquid crystal display device for portable apparatuses which have a touch panel.

  The cover glass is required to be transparent, smooth, and high in physical strength, and a glass plate, an acrylic resin plate, or the like is used.

  The cover glass according to one embodiment of the present invention has a thickness of 0.1 to 0.3 mm. If the thickness is less than 0.1 mm, the strength is insufficient and breakage easily occurs. On the other hand, when the thickness exceeds 0.3 mm, it is not suitable as a liquid crystal display device for portable equipment. According to the horizontal electric field mode type liquid crystal display device according to one embodiment of the present invention, even when the cover glass is made thinner and lighter, the warpage of the panel can be suppressed and the temperature and humidity environment of the liquid crystal display device can be suppressed. An effect of suppressing display unevenness at the time of change can be obtained. The thickness of the cover glass is preferably 0.15 to 0.25 mm from the viewpoint of realizing further thinning while maintaining the strength.

  As a cover glass, a well-known thing can be used, As a commercial item, G-Leaf (trademark) (made by Nippon Electric Glass Co., Ltd.) etc. can be used preferably, for example.

  The cover glass may have a functional layer such as an antireflection layer, an antiglare layer, a scattering prevention layer, or an oil repellent layer on its surface as necessary.

  The method for bonding the cover glass and the other member is not particularly limited, and can be bonded using, for example, a known pressure-sensitive adhesive or adhesive.

[Horizontal electric field mode liquid crystal cell]
The horizontal electric field mode type liquid crystal cell and the liquid crystal display device in this specification include an IPS (In Plane Switching) type and FFS (Fringe-Field Switching) type liquid crystal cell, and a liquid crystal display device.

  Hereinafter, an IPS type display device will be described as an example, but an FFS type liquid crystal display device also exhibits the same effect.

  The liquid crystal layer of the liquid crystal cell in the IPS type display device is generally homogeneously aligned in parallel with the substrate surface in the initial state, and the director of the liquid crystal layer in the plane parallel to the substrate is in the electrode wiring direction when no voltage is applied. The direction of the director of the liquid crystal layer shifts to a direction perpendicular to the electrode wiring direction when a voltage is applied, and the director direction of the liquid crystal layer is when no voltage is applied. When tilted in the electrode wiring direction by 45 ° compared to the director direction, the liquid crystal layer when the voltage is applied rotates the azimuth angle of the polarization by 90 ° like a half-wave plate, and is transmitted through the output-side polarizing plate. The axis and the azimuth angle of the polarized light coincide with each other to display white.

  In general, the thickness of the liquid crystal layer is constant, but since it is driven by a transverse electric field, it may be possible to increase the response speed to switching by slightly increasing the thickness of the liquid crystal layer, but the thickness of the liquid crystal layer is constant. Even if it is not, it is possible to make the most of the effect, and there is little influence on the change in the thickness of the liquid crystal layer. The thickness of the liquid crystal layer is preferably 2 to 6 μm, more preferably 3 to 5.5 μm. The liquid crystal display device according to this embodiment can be preferably used for portable devices such as a tablet display device and a smartphone in addition to being used for a large liquid crystal television.

  In addition, there is no restriction | limiting in particular about the detail of an IPS type | mold cell, This invention can also be implemented by referring other conventionally well-known technical matters (for example, Unexamined-Japanese-Patent No. 2010-3060 etc.).

  Here, the liquid crystal cell generally has a configuration in which a liquid crystal layer is provided between two substrates.

  As the substrate, a glass substrate is mainly used. Liquid crystal display devices used for portable device applications such as tablet-type display devices and smartphones are also required to be thinner and lighter for glass substrates.

  The thickness of the glass substrate of the transverse electric field mode type liquid crystal cell used in one embodiment of the present invention is not particularly limited, but is preferably 0.2 to 0.7 mm. By setting the thickness to 0.2 mm or more, the strength of the liquid crystal display device is further improved. Further, when the thickness is 0.7 mm or less, the liquid crystal display device can be further reduced in thickness and weight.

  Accordingly, in another aspect of the present invention, a horizontal electric field mode type liquid crystal cell further has a configuration in which a liquid crystal layer is provided between two glass substrates having a thickness of 0.2 to 0.7 mm or less. Type liquid crystal display device.

  From the viewpoint of realizing further thinning while maintaining the strength, the thickness is more preferably 0.2 mm to 0.5 mm.

[First polarizing plate and second polarizing plate]
As described above, the horizontal electric field mode type liquid crystal display device according to one embodiment of the present invention has polarizing plates on both sides of the horizontal electric field mode type liquid crystal cell. A 1st polarizing plate is a polarizing plate arrange | positioned at the visual recognition side of a liquid crystal cell, and is equipped with the polarizing plate protective film F1, the polarizer, and the film F2 from the visual recognition side. The second polarizing plate is a polarizing plate disposed on the backlight side (the side opposite to the viewing side) of the transverse electric field mode type liquid crystal cell. From the viewing side, the film F3, the polarizer, and the polarizing plate protection The film F4 is provided.

  In addition, at least one of the film F2 and the film F3 is a retardation film that satisfies the specific condition, and the one that is not the retardation film of the film F2 and the film F3 is an isotropic film that satisfies the specific condition.

  Here, in order to further improve the optical compensation of the horizontal electric field mode type liquid crystal display device, it is preferable that one of the film F2 and the film F3 is a retardation film and the other is an isotropic film.

  Thus, another embodiment of the present invention is a lateral electric field mode type liquid crystal display device in which one of the film F2 and the film F3 is a retardation film and the other is an isotropic film.

  Among such horizontal electric field mode type liquid crystal display devices, the orientation direction of liquid crystal molecules in the horizontal electric field mode type liquid crystal cell when no voltage is applied is the long side of the horizontal electric field mode type liquid crystal cell (that is, the screen of the liquid crystal display device). A transverse electric field mode type liquid crystal display device in which the film F2 is a retardation film and the film F3 is an isotropic film, and the liquid crystal in a no electric voltage application state in the transverse electric field mode type liquid crystal cell The orientation direction of the molecules is parallel to the long side of the transverse electric field mode type liquid crystal cell (that is, the screen of the liquid crystal display device), the film F2 is an isotropic film, and the film F3 is a retardation film. A lateral electric field mode type liquid crystal display device is more preferable from the viewpoint of optical compensation of the horizontal electric field mode type liquid crystal display device.

  In a general lateral electric field mode type liquid crystal cell, the rubbing direction of the alignment film disposed on the upper and lower glass substrates is parallel to the alignment direction of the liquid crystal molecules when no voltage is applied.

  Here, the alignment direction of the liquid crystal molecules in the horizontal electric field mode type liquid crystal cell in the state where no voltage is applied and the slow axis direction of the retardation film are parallel to each other in the optical compensation of the horizontal electric field mode type liquid crystal display device. It is preferable from the viewpoint.

  Further, in the polarizing plate having a retardation film, the slow axis direction of the retardation film and the absorption axis direction of the polarizer are orthogonal, and the slow axis direction of the retardation film and the transmission axis direction of the polarizer Are preferably parallel from the viewpoint of optical compensation of the transverse electric field mode type liquid crystal display device.

  When the orientation direction of the liquid crystal molecules in the horizontal electric field mode type liquid crystal cell is not applied with voltage, the voltage in the liquid crystal cell is not applied It is more preferable from the viewpoint of optical compensation of the transverse electric field mode type liquid crystal display device that the orientation direction of the liquid crystal molecules in the applied state and the absorption axis direction of the first polarizing plate (polarizer) are orthogonal.

  When the orientation direction of the liquid crystal molecules in the horizontal electric field mode type liquid crystal cell is not applied with a voltage, the voltage in the liquid crystal cell is not marked It is more preferable from the viewpoint of optical compensation of the transverse electric field mode type liquid crystal display device that the alignment direction of the liquid crystal molecules in the applied state and the absorption axis direction of the first polarizing plate (polarizer) are parallel.

  That is, in one preferred embodiment of the present invention, the orientation direction of the liquid crystal molecules in the horizontal electric field mode type liquid crystal cell in a state where no voltage is applied is perpendicular to the long side of the horizontal electric field mode liquid crystal cell (that is, the screen of the liquid crystal display device) The film F2 is a retardation film, the film F3 is an isotropic film, the orientation direction of the liquid crystal molecules in the voltage-free state in the transverse electric field mode type liquid crystal cell, and the retardation phase of the retardation film The axis direction is parallel, the slow axis direction of the retardation film is perpendicular to the absorption axis direction of the first polarizing plate (polarizer), and the slow axis direction of the retardation film is the first polarized light. Transverse electric field mode in which the transmission axis direction of the plate (polarizer) is parallel and the absorption axis direction of the first polarizing plate (polarizer) is orthogonal to the absorption axis direction of the second polarizing plate (polarizer) Type liquid crystal display device.

  In another preferred embodiment of the present invention, the orientation direction of the liquid crystal molecules in a state in which no voltage is applied in the transverse electric field mode type liquid crystal cell is relative to the long side of the transverse electric field mode type liquid crystal cell (that is, the screen of the liquid crystal display device). The parallel direction, the film F2 is an isotropic film, and the film F3 is a retardation film, and the orientation direction of the liquid crystal molecules in the lateral electric field mode type liquid crystal cell without voltage application and the retardation of the retardation film. The phase axis direction is parallel, the slow axis direction of the retardation film is orthogonal to the absorption axis direction of the second polarizing plate (polarizer), and the slow axis direction of the retardation film is Transverse electric field in which the transmission axis direction of the polarizing plate (polarizer) is parallel, and the absorption axis direction of the first polarizing plate (polarizer) is orthogonal to the absorption axis direction of the second polarizing plate (polarizer) It is a mode type liquid crystal display device.

(First polarizer and second polarizer)
A polarizer is a main component of a polarizing plate, and is an element that allows only light having a polarization plane in a certain direction to pass through.

  A typical polarizer known at present is a polyvinyl alcohol polarizing film, which includes a polyvinyl alcohol film dyed with iodine and a dichroic dye dyed.

  For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol%. The ethylene-modified polyvinyl alcohol is also preferably used. Among these, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used. A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has the advantage of less color spots.

  As the polarizer, typically, JP-A No. 51-069644, JP-A No. 2000-338329, JP-A No. 2012-0753563, JP-A No. 2014-059328, and International Publication No. 2010/100917. A thin polarizer described in the above may be used. These thin polarizers can be produced by a production method including a step of stretching a polyvinyl alcohol-based resin layer and a stretching resin base material in a laminate and a step of dyeing. If it is this manufacturing method, even if the polyvinyl alcohol-type resin layer used as a polyvinyl-alcohol-type polarizing film is thin, it will be possible to extend | stretch without troubles, such as a fracture | rupture by extending | stretching, by being supported by the resin base material for extending | stretching. .

  The film thickness of the polarizer is 1 to 15 μm. When the thickness of the polarizer is less than 1 μm, sufficient polarization performance cannot be obtained. Further, when the thickness of the polarizer exceeds 15 μm, display unevenness occurs. The display unevenness is considered to be caused by an increase in contraction force in the stretching direction (orientation direction) caused by long-term use in a high-temperature and high-humidity environment, and an increase in warpage of the panel. In order to solve such a problem, the film thickness of the polarizer is set in the above range. From the viewpoint of further improving the polarization performance and suppressing display unevenness, the thickness of the polarizer is preferably 3 to 12 μm, and more preferably 5 to 10 μm.

  The polarizer is provided as a first polarizer and a second polarizer in each of the first polarizing plate and the second polarizing plate. The first polarizing plate and the second polarizing plate, and the first polarizer and the second polarizer may be the same as or different from each other.

  In a horizontal electric field mode type liquid crystal display device, the absorption axis of the first polarizing plate (first polarizer) and the absorption axis of the second polarizing plate (second polarizer) are usually arranged orthogonally. The

  The bonding between the polarizing plate and another adjacent member such as a horizontal electric field mode type liquid crystal cell is preferably bonded via an adhesive layer.

(Polarizing plate protective film F1, F4)
The polarizing plate protective films F1 and F4 are films having a function of protecting the polarizer from moisture, ultraviolet rays, and the like.

  The polarizing plate protective film used for the polarizing plate protective films F1 and F4 is not particularly limited as long as it satisfies the shrinkage rate of the polarizing plate protective film described below, and various polarizing plate protective films conventionally used for polarizing plates. Can be used.

  As the polarizing plate protective film, it is preferable to use a thermoplastic resin film that is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like. The thermoplastic resin used in the thermoplastic resin film is not particularly limited. For example, cellulose resin, polyester resin such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyethersulfone resin, polysulfone resin, polycarbonate Resin, polyamide resin such as nylon and aromatic polyamide, polyimide resin, polyethylene resin, polyolefin resin such as polypropylene, ethylene / propylene copolymer, (meth) acrylic resin such as polymethyl methacrylate (PMMA), Examples thereof include cyclic polyolefin resins such as cycloolefin polymer (COP) and cycloolefin copolymer (COC), polyarylate resins, polystyrene resins, and polyvinyl alcohol resins. Two or more of these thermoplastic resins may be used. Among these, from the viewpoint of low moisture permeability and shrinkage, polymethyl methacrylate (PMMA), cycloolefin polymer (COP), and polyethylene terephthalate (PET) are preferable, and polyethylene terephthalate (PET) and cycloolefin polymer ( COP) is more preferred.

  Moreover, a polarizing plate protective film may contain the additive which can be added to the below-mentioned retardation film.

  Commercially available products may be used as the polarizing plate protective film. Examples of commercially available products include Acrylite (registered trademark) series manufactured by Mitsubishi Rayon Co., Ltd., Toyobo Ester Film E7002 manufactured by Toyobo Co., Ltd., manufactured by Nippon Zeon Co., Ltd. Zeonore film (registered trademark) ZF14 or the like can be used. The polarizing plate protective film is produced by a known method. The production method is not particularly limited, and a film produced by a solution casting method or a film produced by a melt casting method can be preferably used. Moreover, the polarizing plate protective film may be manufactured through stretching.

  For example, as an example of a method for producing a polyester resin film such as polyethylene terephthalate (PET), a polyester resin is melted, and a non-oriented polyester extruded and formed into a sheet shape is heated at a temperature equal to or higher than the glass transition temperature. Examples include a method in which the difference is used to stretch in the longitudinal direction and then stretched in the transverse direction with a tenter and subjected to heat treatment.

  The polarizing plate protective film may have a known functional layer. Although it does not restrict | limit especially as a functional layer, For example, besides an anti-glare layer or a clear hard coat layer, an antireflection layer, an antistatic layer, an antifouling layer, a backcoat layer etc. are mentioned.

(Film characteristics)
<Film thickness>
The thickness of the polarizing plate protective film that can be used as the polarizing plate protective films F1 and F4 is not particularly limited, but is preferably 10 to 100 μm, more preferably 20 to 80 μm, and 30 to 60 μm. More preferably it is.

<Shrinkage factor>
As for the polarizing plate protective film which can be used as polarizing plate protective film F1 and F4, the shrinkage rate measured by the following method A is 0.01 to 0.50%.

[Method A]
The film viewed from the position in the polarizing plate in a 90% relative humidity 90% environment for about 100 hours, parallel to the absorption axis direction of the polarizer, the direction orthogonal to the absorption axis direction of the polarizer, the absorption axis of the polarizer Measure the shrinkage in 4 directions, 45 ° from the direction and 135 ° from the absorption axis direction of the polarizer, and set the largest value as the shrinkage.

  The shrinkage rate can be determined by measuring the distance between two specific points when placed in an environment of 80 ° C. and 90% relative humidity and after 100 hours and left in an environment of 23 ° C. and 55% relative humidity for 1 hour. Further, in accordance with JIS K6911, a heat shrinkage measuring device Model No. It can be measured using EGTP-501 (manufactured by Eager Corporation). Details of the measurement method are described in the examples.

  The inventors of the present invention have confirmed the relationship between the shrinkage rate of the polarizing plate protective films F1 and F4 obtained by Method A and the display unevenness of the transverse electric field mode type liquid crystal display device. Method A is a method for measuring the shrinkage rate of the polarizing plate protective films F1 and F4.

  The reason for the high correlation between the shrinkage rate of Method A and the display unevenness of the horizontal electric field mode type liquid crystal display device is estimated as follows.

  The display unevenness of the transverse electric field mode type liquid crystal display device is considered to have the highest correlation with the shrinkage rate in the direction showing the largest shrinkage rate among the polarizing plate protective films F1 and F4. In general, the shrinkage of a film caused by aging in a high-temperature and high-humidity environment has the largest shrinkage rate in the direction of highest orientation in the plane. Here, as a method for simply estimating the orientation direction of the film, a method of measuring the optical anisotropy and estimating the orientation direction from the slow axis direction or a direction perpendicular to the slow axis direction, and the like can be mentioned. However, since the polarizing plate protective film is not intended for optical compensation, a film with little retardation in the in-plane direction and a very small anisotropy or a film with a very large retardation in the in-plane direction is used. It can be done. Here, it is considered that the slow axis direction of the film having small anisotropy is buried in the orientation variation in the film plane, and it is difficult to determine the slow axis direction when viewed as the whole film. In addition, the slow axis direction of a film with large anisotropy makes it difficult to determine the slow axis direction when viewed as the whole film because variations in anisotropy in the plane are easily detected. It is done. Therefore, with reference to the absorption axis direction of the polarizer in the polarizing plate state, the polarizing plate protective film has a direction parallel to the absorption axis direction of the polarizer, a direction orthogonal to the absorption axis direction of the polarizer, and 45 from the absorption axis direction of the polarizer. By measuring the shrinkage rate in the four directions of 135 ° direction from the ° direction and the absorption axis direction of the polarizer, and taking the largest value as the shrinkage rate, a shrinkage rate close to the maximum shrinkage rate at least in the film plane can be obtained. it is conceivable that. And it is thought that the shrinkage | contraction rate of polarizing plate protective film F1 obtained by such a method has sufficient correlation to confirm the relationship of the display nonuniformity of a horizontal electric field mode type liquid crystal display device. Note that the above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention.

  When the shrinkage rate of the polarizing plate protective film is less than 0.01%, it is a case where a certain degree of hydrophobicity is imparted to the film, and it is dry when bonded to a polarizer with a water-soluble adhesive (water glue bonding). Lowers productivity. Further, when the shrinkage rate of the polarizing plate protective film exceeds 0.50%, display unevenness when the temperature and humidity environment of the liquid crystal display device changes due to the shrinkage of the film becomes remarkable. In order to solve such a problem, the shrinkage rate of the polarizing plate protective film is set to the above range. From the viewpoint of further suppressing display unevenness, the shrinkage rate is preferably 0.01 to 0.40%, more preferably 0.01 to 0.25%, and 0.01 to 0.10%. More preferably it is.

  The shrinkage rate is controlled by a known method such as the type of film forming material such as a thermoplastic resin to be used, the amount of additive to be used if necessary, the film thickness, the stretching temperature, and the production conditions such as the stretching ratio. Can do. Moreover, since the polarizing plate protective film which concerns on one form of this invention tends to also become small in a shrinkage rate by making the below-mentioned moisture permeability small, it is also preferable to set it as the design which reduces moisture permeability.

<Moisture permeability>
The moisture permeability of the polarizing plate protective film can be measured according to a moisture permeability test (cup method) of JIS Z0208. In the present application, the moisture permeability uses a value converted to a film thickness of 40 μm. Details of the measurement method are described in the examples.

The polarizing plate protective film that can be used as the polarizing plate protective films F1 and F4 preferably has a moisture permeability of 1.0 to 60 (g / m ² / 24h) in terms of a film thickness of 40 μm. When the moisture permeability is 1.0 (g / m ² / 24h) or more, the adhesion (water glue adhesion) by the water-soluble adhesive at the time of producing the polarizing plate is improved. If the moisture permeability is 60 (g / m ² / 24h) or less, the effect of temperature and humidity can be reduced by hydrophobizing the film and the film shrinkage over time can be reduced. The effect of suppressing display unevenness when the temperature and humidity environment of the liquid crystal display device is changed is further enhanced. From the viewpoint of suppression of additional display unevenness, the moisture permeability is more preferably ^{1.0~50 (g / m 2 / 24h} ), more preferably from ^{1.0~40 (g / m 2 / 24h} ).

  The moisture permeability can be controlled by the type of film forming material such as a thermoplastic resin to be used, the amount of additive to be used if necessary, the film thickness, and the like.

(Films F2, F3)
(Retardation film)
The retardation film used for at least one of the films F2 and F3 is a film having a function of expanding the viewing angle of the transverse electric field mode type liquid crystal display device by performing optical compensation.

  The retardation film is preferably a film that also functions as a polarizing plate protective film. In that case, in addition to the films F2 and F3 and the polarizing plate protective films F1 and F4, a further polarizing plate protective film is provided. There is no need to prepare it separately. Thus, the thickness of the liquid crystal display device can be reduced and the manufacturing process can be simplified.

<Cellulose acylate having an aromatic acyl group>
The retardation film is a cellulose acylate film containing as a main component a cellulose acylate having an aromatic acyl group.

  Since the aromatic acyl group has a wide π-conjugated system, it exists in an in-plane orientation to increase the refractive index anisotropy of the retardation film, resulting in a large in-plane retardation R0. . Moreover, the thickness direction retardation Rth can be kept at a low value by being oriented in the thickness direction. Accordingly, in-plane retardation R0 and thickness direction retardation Rth suitable for optical compensation of the transverse electric field mode type liquid crystal display device can be obtained, and therefore, cellulose acylate having an aromatic acyl group is used.

  In this specification, the cellulose acylate film containing a cellulose acylate having an aromatic acyl group as a main component means that the content of the cellulose acylate having an aromatic acyl group is 70% by mass relative to the total mass of the film. It represents exceeding. When the content of cellulose acylate having an aromatic acyl group is 70% by mass or less, an in-plane retardation R0 and a thickness direction retardation Rth giving sufficient viewing angle performance to a transverse electric field mode type liquid crystal display device are obtained. It becomes difficult. From the same viewpoint, the retardation film further preferably contains 80% by mass or more of cellulose acylate having an aromatic acyl group, and particularly preferably contains 90% by mass or more.

  The aromatic acyl group may have a structure in which the aromatic group is directly bonded to the carbonyl group, or may have a structure in which the aromatic group is bonded via a linking group. Among these, it is preferable that the aromatic group has a structure directly bonded to a carbonyl group. Examples of the linking group include an alkylene group, an alkenylene group, and an alkynylene group. Among these, as the linking group, an alkylene group, an alkenylene group and an alkynylene group having 1 to 10 carbon atoms, more preferably an alkylene group, an alkenylene group and an alkynylene group having 1 to 6 carbon atoms. More preferably an alkylene group, an alkenylene group, and an alkynylene group having 1 to 6 carbon atoms. The linking group may further have a substituent.

  The aromatic group constituting the aromatic acyl group may be an aromatic hydrocarbon group or an aromatic heterocyclic group. Aromatics are defined as aromatic compounds in the 4th edition, 1208 of the Riken Dictionary (Iwanami Shoten).

  As the aromatic hydrocarbon group, those having 6 to 24 carbon atoms are preferable, those having 6 to 12 carbon atoms are more preferable, and those having 6 to 10 carbon atoms are more preferable. Although it does not restrict | limit especially as an aromatic hydrocarbon group, For example, a phenyl group, a naphthyl group, an anthryl group, a biphenyl group, a terphenyl group etc. are mentioned. Among these, a phenyl group, a naphthyl group, and a biphenyl group are more preferable, and a phenyl group is more preferable.

  As the aromatic heterocyclic group, those containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom are preferred. The hetero group constituting the aromatic heterocyclic group is not particularly limited. For example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline. , Oxazole, oxadiazole, quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene, etc. . Among these, a pyridyl group, a triazinyl group, and a quinolyl group are preferable. The aromatic group may further have a substituent.

  The substituent that the linking group or aromatic group may have is not particularly limited, and examples thereof include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, an acyl group, and an alkoxy group. Carbonyl group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, sulfinyl group, ureido group, Examples thereof include phosphoric acid amide group, hydroxy group, mercapto group, halogen atom, cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group, silyl group and the like. These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. Further, if possible, they may be linked to each other to form a ring.

  Here, the alkyl group is not particularly limited, but preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group, Examples include isopropyl group, tert-butyl group, n-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl, cyclohexyl group and the like. Although it does not restrict | limit especially as an alkenyl group, Preferably it is C2-C20, More preferably, it is 2-12, Most preferably, it is 2-8, for example, a vinyl group, an allyl group, 2-butenyl group, 3-pentenyl. Groups and the like. Although it does not restrict | limit especially as an alkynyl group, Preferably it is C2-C20, More preferably, it is 2-12, Most preferably, it is 2-8, For example, a propargyl group, 3-pentynyl group, etc. are mentioned. Although it does not restrict | limit especially as an aryl group, Preferably it is C6-C30, More preferably, it is 6-20, Most preferably, it is 6-12, for example, a phenyl group, a biphenyl group, a naphthyl group etc. are mentioned. Although it does not restrict | limit especially as an amino group, Preferably it is C0-20, More preferably, it is 0-10, Most preferably, it is 0-6, for example, an amino group, a methylamino group, a dimethylamino group, a diethylamino group, And dibenzylamino group. Although it does not restrict | limit especially as an alkoxy group, Preferably it is C1-C20, More preferably, it is 1-12, Most preferably, it is 1-8, for example, a methoxy group, an ethoxy group, a butoxy group etc. are mentioned. Although it does not restrict | limit especially as an aryloxy group, Preferably it is C6-C20, More preferably, it is 6-16, Most preferably, it is 6-12, for example, a phenyloxy group, 2-naphthyloxy group, etc. are mentioned. . Although it does not restrict | limit especially as an acyl group, Preferably it is C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, for example, an acetyl group, a benzoyl group, a formyl group, a pivaloyl group etc. are mentioned. It is done. Although it does not restrict | limit especially as an alkoxycarbonyl group, Preferably it is C2-C20, More preferably, it is 2-16, Most preferably, it is 2-12, for example, a methoxycarbonyl group, an ethoxycarbonyl group, etc. are mentioned. Although it does not restrict | limit especially as an aryloxycarbonyl group, Preferably it is C7-20, More preferably, it is 7-16, Most preferably, it is 7-10, for example, a phenyloxycarbonyl group etc. are mentioned. Although it does not restrict | limit especially as an acyloxy group, Preferably it is C2-C20, More preferably, it is 2-16, Most preferably, it is 2-10, For example, an acetoxy group, a benzoyloxy group, etc. are mentioned. Although it does not restrict | limit especially as an acylamino group, Preferably it is C2-C20, More preferably, it is 2-16, Most preferably, it is 2-10, For example, an acetylamino group, a benzoylamino group, etc. are mentioned. Although it does not restrict | limit especially as an alkoxycarbonylamino group, Preferably it is C2-C20, More preferably, it is 2-16, Most preferably, it is 2-12, For example, a methoxycarbonylamino group etc. are mentioned. Although it does not restrict | limit especially as an aryloxycarbonylamino group, Preferably it is C7-20, More preferably, it is 7-16, Most preferably, it is 7-12, for example, a phenyloxycarbonylamino group etc. are mentioned. Although it does not restrict | limit especially as a sulfonylamino group, Preferably it is C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, for example, a methanesulfonylamino group, a benzenesulfonylamino group, etc. are mentioned. . Although it does not restrict | limit especially as a sulfamoyl group, Preferably it is C0-20, More preferably, it is 0-16, Most preferably, it is 0-12, for example, a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group. And phenylsulfamoyl group. Although it does not restrict | limit especially as a carbamoyl group, Preferably it is C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, for example, carbamoyl group, methylcarbamoyl group, diethylcarbamoyl group, phenylcarbamoyl group Etc. Although it does not restrict | limit especially as an alkylthio group, Preferably it is C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, for example, a methylthio group, an ethylthio group, etc. are mentioned. Although it does not restrict | limit especially as an arylthio group, Preferably it is C6-C20, More preferably, it is 6-16, Most preferably, it is 6-12, for example, a phenylthio group etc. are mentioned. Although it does not restrict | limit especially as a sulfonyl group, Preferably it is C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, For example, a mesyl group, a tosyl group, etc. are mentioned. Although it does not restrict | limit especially as a sulfinyl group, Preferably it is C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, for example, a methanesulfinyl group, a benzenesulfinyl group, etc. are mentioned. Although it does not restrict | limit especially as a ureido group, Preferably it is C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, for example, a ureido group, a methylureido group, a phenylureido group etc. are mentioned. . Although it does not restrict | limit especially as a phosphoric acid amide group, Preferably it is C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, for example, diethyl phosphoric acid amide, phenylphosphoric acid amide etc. are mentioned. It is done. Although it does not restrict | limit especially as a halogen atom, For example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned. Although it does not restrict | limit especially as a heterocyclic group, Preferably it is C1-C30, More preferably, it is 1-12, As a hetero atom, a nitrogen atom, an oxygen atom, a sulfur atom etc. are mentioned, for example. Examples include imidazolyl group, pyridyl group, quinolyl group, furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group and the like. Although it does not restrict | limit especially as a silyl group, Preferably, it is C3-C40, More preferably, it is 3-30, Most preferably, it is 3-24, For example, a trimethylsilyl group, a triphenylsilyl group, etc. are mentioned.

  The aromatic acyl group is not particularly limited, and examples thereof include a phenylacetyl group, a hydrocinnamoyl group, a diphenylacetyl group, a phenoxyacetyl group, a benzyloxyacetyl group, an O-acetylmandelyl group, a 3-methoxyphenylacetyl group, 4-methoxyphenylacetyl group, 2,5-dimethoxyphenylacetyl group, 3,4-dimethoxyphenylacetyl group, 9-fluorenylmethylacetyl group, cinnamoyl group, 4-methoxy-cinnamoyl group, benzoyl group, ortho-toluoyl Group, meta-toluoyl group, para-toluoyl group, m-anisoyl group, p-anisoyl group, phenylbenzoyl group, 4-ethylbenzoyl group, 4-propylbenzoyl group, 4-t-butylbenzoyl group, 4-butylbenzoyl Group, 4-pentylbenzoy Group, 4-hexylbenzoyl group, 4-heptylbenzoyl group, 4-octylbenzoyl group, 4-vinylbenzoyl group, 4-ethoxybenzoyl group, 4-butoxybenzoyl group, 4-hexyloxybenzoyl group, 4-heptyloxy Benzoyl, 4-pentyloxybenzoyl, 4-octyloxybenzoyl, 4-nonyloxybenzoyl, 4-decyloxybenzoyl, 4-undecyloxybenzoyl, 4-dodecyloxybenzoyl, 4-isopropoxy Benzoyl group, 2,3-dimethoxybenzoyl group, 2,5-dimethoxybenzoyl group, 3,4-dimethoxybenzoyl group, 2,6-dimethoxybenzoyl group, 2,4-dimethoxybenzoyl group, 3,5-dimethoxybenzoyl group 3,4,5-trimethoxybenzoyl group, 2, , 5-trimethoxybenzoyl group, 1-naphthoyl group, 2-naphthoyl group, 2-biphenylcarbonyl group, 4-biphenylcarbonyl group, 4′-ethyl-4-biphenylcarbonyl group, 4′-octyloxy-4-biphenylcarbonyl Group, piperonylyl group, diphenylacetyl group, triphenylacetyl group, phenylpropionyl group, hydrocinnamoyl group, α-methylhydrocinnamoyl group, 2,2-diphenylpropionyl group, 3,3-diphenylpropionyl group, 3,3 , 3-triphenylpropionyl group, 2-phenylbutyryl group, 3-phenylbutyryl group, 4-phenylbutyryl group, 5-phenylvaleryl group, 3-methyl-2-phenylvaleryl group, 6-phenyl Hexanoyl group, α-methoxyphenylacetyl group, phenoxy Cetyl group, 3-phenoxypropionyl group, 2-phenoxypropionyl group, 11-phenoxydecanoyl group, 2-phenoxybutyryl group, 2-methoxyacetyl group, 3- (2-methoxyphenyl) propionyl group, 3- (p -Toluyl) propionyl group, (4-methylphenoxy) acetyl group, 4-isobutyl-α-methylphenylacetyl group, 4- (4-methoxyphenyl) butyryl group, (2,4-di-t-pentylphenoxy)- Acetyl group, 4- (2,4-di-t-pentylphenoxy) -butyryl group, (3,4-dimethoxyphenyl) acetyl group, 3,4- (methylenedioxy) phenylacetyl group, 3- (3 4-dimethoxyphenyl) propionyl group, 4- (3,4-dimethoxyphenyl) butyryl group, (2,5-dimethoxy) Enyl) acetyl group, (3,5-dimethoxyphenyl) acetyl group, 3,4,5-trimethoxyphenylacetyl group, 3- (3,4,5-trimethoxyphenyl) -propionyl group, acetyl group, 1- Naphthylacetyl group, 2-naphthylacetyl group, α-trityl-2-naphthalene-propionyl group, (1-naphthoxy) acetyl group, (2-naphthoxy) acetyl group, 6-methoxy-α-methyl-2-naphthaleneacetyl group 9-fluoreneacetyl group, 1-pyreneacetyl group, 1-pyrenebutyryl group, γ-oxo-pyrenebutyryl group, styreneacetyl group, α-methylcinnamoyl group, α-phenylcinnamoyl group, 2-methylcinnamoyl group, 2-methoxycinnamoyl group, 3-methoxycinnamoyl group, 2,3-dimethoxycinnamoyl group 2,4-dimethoxycinnamoyl group, 2,5-dimethoxycinnamoyl group, 3,4-dimethoxycinnamoyl group, 3,5-dimethoxycinnamoyl group, 3,4- (methylenedioxy) cinnamoyl group, 3 , 4,5-trimethoxycinnamoyl group, 2,4,5-trimethoxycinnamoyl group, 3-methylidene-2-carbonyl group, 4- (2-cyclohexyloxy) benzoyl group, 2,3-dimethylbenzoyl group 2,6-dimethylbenzoyl group, 2,4-dimethylbenzoyl group, 2,5-dimethylbenzoyl group, 3-methoxy-4-methylbenzoyl group, 3,4-diethoxybenzoyl group, α-phenyl-O— Toluyl group, 2-phenoxybenzoyl group, 2-benzoylbenzoyl group, 3-benzoylbenzoyl group, 4-benzoylbenzoy Group, 2-ethoxy-1-naphthoyl group, 9-fluorene group, 1-fluorene group, 4-fluorene group, 9-anthracene group, 1-pyrene group and the like. Moreover, the aromatic acyl group may be one kind or two or more kinds.

  Among these, more preferable in-plane retardation R0 and thickness direction retardation Rth can be obtained from the viewpoint of optical compensation of the transverse electric field mode type liquid crystal display device, and the steric hindrance is small, cheaper, and easy to synthesize. From the viewpoint of being present, a benzoyl group is preferred.

  In addition to the aromatic acyl group, the cellulose acylate having an aromatic acyl group preferably contains another acyl group because the water resistance can be improved by substituting the OH group. The other acyl group preferably contains an aliphatic acyl group because of improved water resistance, small steric hindrance, and ease of synthesis.

  The aliphatic acyl group may be a linear, branched or cyclic aliphatic acyl group, or may be an aliphatic acyl group containing an unsaturated bond. Further, the aliphatic acyl group may be one kind or two or more kinds.

  As the aliphatic acyl group, those having 2 to 20 carbon atoms are preferable, those having 2 to 10 carbon atoms are more preferable, and those having 2 to 4 carbon atoms are more preferable. Although it does not restrict | limit especially as an aliphatic acyl group, For example, an acetyl group, a propionyl group, a butyryl group, etc. are mentioned. Among these, an acetyl group and a propionyl group are preferable, and an acetyl group is more preferable from the viewpoint that the water resistance can be further improved and the synthesis is easy.

The cellulose acylate having an aromatic acyl group preferably has an aromatic acyl group substitution degree DSA of the following formula (III) and a total substitution degree DS of the following formula (IV);
Formula (III) 0.5 ≦ DSA ≦ 2.0
Formula (IV) 1.0 ≦ DS ≦ 3.0
When the aromatic acyl group substitution degree DSA is 0.5 to 2.0, the in-plane retardation R0 and the thickness direction retardation Rth are adjusted to a range in which the viewing angle characteristics of the liquid crystal display device are further improved. This is preferable. In addition, by making the film hydrophobic, the influence of temperature and humidity can be reduced, and the film shrinkage rate over time can be reduced. Therefore, display irregularities when the temperature and humidity environment of the liquid crystal display device changes due to film shrinkage. The suppression effect of increases.

  Accordingly, in another embodiment of the present invention, the cellulose acylate having an aromatic acyl group has an aromatic acyl group substitution degree DSA of the above formula (III) and a total substitution degree DS of the above formula (IV). A horizontal electric field mode type liquid crystal display device.

  From the viewpoint of achieving both the effect of improving viewing angle characteristics and the effect of reducing the shrinkage rate, the aromatic acyl group substitution degree DSA is more preferably 1.0 to 1.5.

  The total acyl group substitution degree of 1.0 or more is preferable because the viewing angle characteristics of the liquid crystal display device can be further improved by increasing the expression of the in-plane retardation R0 (upper limit is 3.0). ). From the viewpoint of such viewing angle characteristics, the total acyl group substitution degree is more preferably 1.5 or more, and further preferably 2.5 or more (upper limit 3.0).

  Moreover, when the cellulose acylate having an aromatic acyl group further has an aliphatic acyl group, the aliphatic acyl group substitution degree DSB is preferably 0.5 to 2.5. The in-plane retardation R0 and the thickness direction retardation Rth are preferably in the above ranges because the viewing angle characteristics of the liquid crystal display device can be further improved. From the viewpoint of the effect of improving the viewing angle characteristics, the aliphatic acyl group substitution degree DSB is more preferably 1.1 to 1.9, and further preferably 1.4 to 1.6.

The substitution degree and the substitution degree distribution of the substituent in the cellulose acylate having an aromatic acyl group are determined using the method described in Cellulose Communication 6, 73-79 (1999) and Chirality 12 (9), 670-674. , ¹ H-NMR or ¹³ C-NMR.

  The viscosity average polymerization degree of the cellulose ester is preferably 80 to 700, more preferably 90 to 500, still more preferably 140 to 400, and particularly preferably 200 to 300. The viscosity average degree of polymerization of the cellulose ester can be measured according to Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). A method for measuring the viscosity average degree of polymerization is also described in JP-A-9-95538.

  The weight average molecular weight (Mw) of the cellulose acylate having an aromatic acyl group is preferably in the range of 100,000 to 400,000 because the mechanical strength of the resulting film is strong. Furthermore, the thing of 150,000-350,000 is used preferably.

  The cellulose acylate having an aromatic acyl group preferably has a weight average molecular weight (Mw) / number average molecular weight (Mn) value of 1.0 to 5.0, preferably 2.0 to 4.0. Is more preferable.

  The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose acylate having an aromatic acyl group can be measured using gel permeation chromatography (GPC).

  An example of measurement conditions is as follows, but is not limited to this, and an equivalent measurement method can be used.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves using 13 samples are used. Thirteen samples are used at approximately equal intervals.

  Specific examples of the cellulose acylate having an aromatic acyl group include, for example, a cellulose acylate having a substituent and a degree of substitution used in Examples described later, but is not limited to these examples.

  The cellulose acylate having an aromatic acyl group is a compound having a cellulose skeleton obtained by introducing at least an aromatic group acyl group biologically or chemically using cellulose as a raw material.

  The raw material cotton of cellulose acylate having aromatic acyl group is not only natural cellulose such as cotton linter and wood pulp (hardwood pulp, conifer pulp), but also the degree of polymerization obtained by acid hydrolysis of wood pulp such as microcrystalline cellulose. Low (degree of polymerization 100-300) cellulose can also be used, and may be mixed and used in some cases. Detailed descriptions of these raw material celluloses can be found in, for example, “Plastic Materials Course (17) Fibrous Resin” (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970), Japan Institute of Invention Technology Publication 2001-1745 ( 7 to 8) or “Encyclopedia of Cellulose (page 523)” (edited by Cellulose Society, Asakura Shoten, published in 2000) and the like. The raw material cellulose is not particularly limited, but celluloses described therein may be used.

  The cellulose acylate having an aromatic acyl group is, for example, cellulose acetate (acetyl substitution degree 2.45) manufactured by Aldrich, or cellulose acetate (acetyl substitution degree 2.41 (trade name: L-70), manufactured by Daicel Corporation. 19 (trade name: FL-70)) and 1.76 (trade name: LL-10) as starting materials, and can be obtained by reaction with the corresponding acid chloride.

  In addition to cellulose acylate having an aromatic acyl group, the retardation film is described below. Plasticizer for imparting processability / flexibility / moisture resistance to the film, ultraviolet absorber for imparting ultraviolet absorption function, film Retardation control agent for adjusting the in-plane retardation R0 and thickness direction retardation Rth to desired values, an antioxidant for preventing deterioration of the film, and fine particles (matting agent) for imparting slipperiness to the film, etc. The additive may be contained.

<Plasticizer>
The plasticizer is not particularly limited, and examples thereof include sugar ester plasticizers, polyhydric alcohol ester plasticizers, glycolate plasticizers, phthalate ester plasticizers, fatty acid ester plasticizers, and phosphate ester plasticizers. It is preferably selected from an agent, a polyvalent carboxylic ester plasticizer, a polyester plasticizer, a vinyl polymer plasticizer, and the like. Two or more of these plasticizers may be used.

  The plasticizer is preferably contained in an amount of 0.5 to 30 parts by mass, more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the cellulose acylate having an aromatic acyl group.

<Ultraviolet absorber>
The ultraviolet absorber is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the polarizer or the display device with respect to ultraviolet rays, and has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of color. Is preferred.

  Although it does not restrict | limit especially as an ultraviolet absorber, For example, a benzotriazole type compound, a triazine type compound, a benzophenone type compound, a cyanoacrylate type compound, a salicylic acid ester type compound, a nickel complex salt type compound etc. can be mentioned. Among these, benzotriazole compounds, triazine compounds, and benzophenone compounds are preferable. Further, ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574, or polymer ultraviolet absorptions described in JP-A-6-148430, JP-A-2003-113317, etc. An agent may be used. Two or more of these ultraviolet absorbers may be used.

  The ultraviolet absorber is preferably contained in an amount of 0.1 to 5 parts by mass, more preferably 0.2 to 3% by mass, relative to 100 parts by mass of the cellulose acylate having an aromatic acyl group. It is more preferable to include 2 parts by mass.

<Retardation control agent>
The compound added to adjust the retardation uses an aromatic compound having two or more aromatic rings as described in EP 911,656, as a retardation control agent. You can also Or the rod-shaped compound of Unexamined-Japanese-Patent No. 2006-2025 is mentioned. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound is particularly preferably an aromatic heterocyclic ring including an aromatic heterocyclic ring in addition to an aromatic hydrocarbon ring, and the aromatic heterocyclic ring is generally an unsaturated hetero ring. It is a ring. Of these, the 1,3,5-triazine ring described in JP-A-2006-2026 is particularly preferable.

<Antioxidant>
Antioxidants are also referred to as deterioration inhibitors. When a liquid crystal display device or the like is placed in a high humidity and high temperature state, the retardation film may be deteriorated. The antioxidant has a role of delaying or preventing the decomposition of the retardation film due to, for example, halogen in the amount of residual solvent in the retardation film or phosphoric acid when a phosphoric acid plasticizer is used.

  Such an antioxidant is not particularly limited, and examples thereof include hindered phenol compounds.

  The antioxidant is preferably contained in an amount of 0.01 to 1.0 part by mass, more preferably 0.05 to 0.5 part by mass with respect to 100 parts by mass of the cellulose acylate having an aromatic acyl group.

<Fine particles>
The retardation film preferably contains fine particles.

  The fine particles are not particularly limited as inorganic compounds. For example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate And aluminum silicate, magnesium silicate and calcium phosphate. Further, fine particles of an organic compound can also be preferably used. The organic compound is not particularly limited. For example, polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine. Resin, melamine resin, polyolefin powder, polyester resin, polyamide resin, polyimide resin, and the like, and pulverized classification of organic polymer compounds such as polyfluorinated ethylene resin and starch are also included. . Further, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray dry method or a dispersion method, or an inorganic compound may be used.

  Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is more preferable.

  The average primary particle size of the fine particles is preferably 5 to 400 nm, more preferably 10 to 300 nm.

  These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm. Moreover, it is also preferable that it is contained as a primary particle, without aggregating, if it is a particle with an average particle diameter of 100-400 nm.

  The content of these fine particles in the retardation film is preferably 0.001 to 1% by mass, and more preferably 0.001 to 0.5% by mass. In the case of a film having a multilayer structure formed by a co-casting method, it is preferable that the surface contains this amount of fine particles.

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

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

  Examples of the organic compound fine particles include silicone resins, fluororesins, and acrylic resins. Among these, silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120 and 240 (above Toshiba Silicone Co., Ltd.) ) And can be used.

  Among these fine particles, Aerosil 200V and Aerosil R972V are particularly preferable because they have a large effect of reducing the friction coefficient while keeping the turbidity of the optical film low. In the retardation film, it is preferable that the dynamic friction coefficient of at least one surface is 0.2 to 1.0.

  Various additives may be batch-added to a dope (cellulose acylate having an aromatic acyl group and an additive to be added if necessary) before film formation, or the additive is dissolved or dissolved. A dispersed additive additive solution may be separately prepared and added in-line. In particular, in order to reduce the load on the filter medium, it is preferable to add a part or all of the fine particles in-line using an additive additive solution (fine particle additive solution).

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

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

<Functional layer>
The retardation film may have a known functional layer. Although it does not restrict | limit especially as a functional layer, For example, an optically anisotropic layer etc. are mentioned.

<Production method>
Next, the manufacturing method of retardation film is demonstrated.

  The retardation film can be preferably used regardless of whether it is a film produced by a solution casting method or a film produced by a melt casting method. In the following, the solution pouring method will be described as an example, but the manufacturing method is not limited to this.

  The production of a retardation film by the solution-flow method is a process for preparing a dope by dissolving a cellulose acylate having an aromatic acyl group and an additive to be added as necessary in a solvent, and an endless transition of the dope. Performed by a process of casting on a metal support, a process of drying the cast dope as a web, a process of peeling from the metal support, a process of stretching or maintaining the width, a process of drying, and a process of winding up the finished film Is called.

Dope preparation step The concentration of the cellulose acylate having an aromatic acyl group in the dope is preferably higher if the drying load after casting on a metal support can be reduced, but if the concentration is too high, the load during filtration will be reduced. It increases and the filtration accuracy worsens. The concentration for achieving both of these is preferably 10 to 35% by mass, more preferably 15 to 25% by mass.

  Solvents used in the dope may be used alone or in combination of two or more. However, it is possible to use a mixture of a good solvent and a poor solvent of cellulose acylate having an aromatic acyl group in terms of production efficiency. In view of the solubility of the cellulose acylate having an aromatic acyl group, it is preferable that the amount of the good solvent is larger. The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose acylate which has the aromatic acyl group to be used independently is defined as a good solvent, and the thing which swells independently or does not melt | dissolve is defined as a poor solvent. Therefore, for example, the good solvent and the poor solvent change depending on the substituent or degree of substitution of the cellulose acylate having an aromatic acyl group. Therefore, the good solvent and the poor solvent are appropriately checked, and the mixing ratio is adjusted if necessary. It is preferable.

  The good solvent is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Among these, methylene chloride or methyl acetate is more preferable.

  Moreover, it is although it does not specifically limit as a poor solvent, For example, methanol, ethanol, n-butanol, a cyclohexane, cyclohexanone etc. are mentioned. Moreover, it is preferable that 0.01-2 mass% of water contains in dope. Moreover, the solvent used for melt | dissolving the cellulose acylate which has an aromatic acyl group may collect | recover the solvent removed from the film by drying at the film forming process, and may reuse this. The recovered solvent may contain a small amount of additives, such as plasticizers, UV absorbers, polymers, monomer components, etc. that have been added to the film formed previously, but it is preferable that these are included. It can be reused, and can be purified and reused if necessary.

  As a method for dissolving the cellulose acylate having an aromatic acyl group when preparing the dope, a general method can be used. For example, a method of stirring and dissolving while heating can be mentioned. In addition, when heating and pressurization are combined, heating can be performed to a boiling point or higher at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos. In addition, a method in which cellulose acylate having an aromatic acyl group is mixed with a poor solvent and wetted or swollen, and then a good solvent is further added and dissolved is also preferably used.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of developing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the cellulose acylate having an aromatic acyl group, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. . A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  In addition to the above, a cooling dissolution method is also preferably used, whereby cellulose acylate having an aromatic acyl group can be dissolved in a solvent such as methyl acetate.

  Next, the dope is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.007 mm is more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the cellulose acylate having an aromatic acyl group as a raw material by filtration.

The bright spot foreign matter is arranged in a crossed Nicols state with two polarizing plates, a retardation film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. It is a point (foreign matter) where light from the opposite side sometimes leaks, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less. More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / cm < ² > or less, More preferably, it is 0-10 pieces / cm < ² >. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The expression of the difference (referred to as differential pressure) is small and preferable. A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

Fluxing process The metal support in the casting (casting) process preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be 1 to 4 m.
The temperature of the dope is preferably 10 to 40 ° C., preferably 20 to 35 ° C., from the viewpoint of efficiently dissolving the solid and not recrystallizing, and from the viewpoint of setting the temperature within which the solvent does not volatilize. It is more preferable. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web drying speed can be increased, but if the temperature is too high, the web foams, The flatness may deteriorate. The support temperature is preferably 0 to 40 ° C, and more preferably 5 to 30 ° C. It is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and examples thereof include a method of blowing hot air or cold air, a method of contacting hot water with the back side of the metal support, and the like. The method using hot water is preferable because heat transfer is performed more efficiently, and the time until the temperature of the metal support becomes constant can be shortened. When warm air is used, wind at a temperature higher than the target temperature may be used.

Drying process on metal support The cast dope is dried so that the amount of residual solvent is below a certain level. In order for the retardation film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, or 20 to 40% by mass or 60 to 130% by mass. Is more preferable, and it is still more preferable that it is 20-30 mass% or 70-120 mass%.

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

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M represents the mass of a sample collected at any time during or after the production of the web or film. N represents the mass of the sample after heating M at 115 ° C. for 1 hour.

Peeling process Peeling of the web is performed by a general method, but is preferably peeled by a peeling roll. Peeling with a peeling roll is preferably carried out when the web reaches the lower surface of the metal support and almost completes a round. The web peeling tension is preferably 300 N / m or less.

  The peeling of the web is not only a method of peeling after the web is dried in the above-described drying process on the metal support, but also includes a large amount of residual solvent by cooling the cast film without drying after the previous fluent process. You may peel, after making it gelatinize in a state.

Drying step In the drying step, the web is peeled off from the metal support and further dried to make the residual solvent amount 1% by mass or less, more preferably 0.1% by mass or less, particularly preferably 0. It is -0.01 mass% or less.

  In the drying process, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method of drying while transporting the web by a tenter method are adopted.

  The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but is preferably performed with hot air from the viewpoint of simplicity.

  The drying temperature in the web drying step is preferably increased stepwise from 40 to 200 ° C.

  In addition, in order to produce retardation film, it is preferable that a drying process serves as the below-mentioned extending process.

Stretching step In the step of producing the retardation film, it is preferable to control the refractive index by stretching operation, that is, to control the in-plane retardation R0 and the thickness direction retardation Rth.

  By performing a stretching operation during the above-described drying step, it can also serve as a stretching step. Further, a separate stretching step may be provided after the above-described drying step.

  The stretching of the web is not particularly limited, and may be uniaxial stretching or biaxial stretching in the width direction (lateral direction) or the conveyance direction (longitudinal direction). The web may be stretched in the width direction or in an oblique direction with respect to the dope casting direction. Biaxial stretching includes stretching in both the web conveyance direction (longitudinal direction) and the width direction (lateral direction). Stretching may be sequential stretching or simultaneous stretching.

  In general, when the retardation film has positive birefringence, the stretching direction is the slow axis direction in uniaxial stretching. When the retardation film has negative birefringence, the direction perpendicular to the stretching direction in the uniaxial stretching is the slow axis direction. In the case of biaxial stretching, the slow axis direction is determined by combining the effects of stretching in each direction.

  Here, the uniaxial stretching may be free end uniaxial stretching or fixed end uniaxial stretching, but more preferable in-plane retardation R0 and thickness from the viewpoint of optical compensation of the transverse electric field mode type liquid crystal display device. From the viewpoint that the direction retardation Rth can be obtained, free end uniaxial stretching is preferred.

  Further, in the retardation film of the present invention, the absorption axis direction of the polarizer (longitudinal direction in a general polarizer) and the slow axis direction of the film are orthogonal to each other from the viewpoint of optical compensation of the transverse electric field mode type liquid crystal display device. It is preferable that the longitudinal direction (conveying direction / longitudinal direction) of the retardation film having the axial relationship and the polarizer are bonded to each other when the polarizing plate is produced. In view of this, it is preferable to use a film having negative birefringence as the original film of the retardation film and to perform stretching including at least uniaxial stretching in the transport direction (longitudinal direction).

  When the web is stretched uniaxially in the width direction (transverse direction) or the conveyance direction (longitudinal direction), the draw ratio of the web is finally 10% in the width direction (lateral direction) or the conveyance direction (vertical direction) (1. 10 times) to 50% (1.50 times) is preferable. It is preferable to set the draw ratio to 1.10 times or more in the width direction because the in-plane retardation R0 can be enhanced and the viewing angle characteristics of the liquid crystal display device can be further improved. In addition, the shrinkage rate of the film can be reduced by setting the draw ratio to 1.50 times or less in the width direction, so that the display unevenness when the temperature and humidity environment of the liquid crystal display device changes due to the shrinkage of the film is suppressed. Increases effectiveness. Since the shrinkage ratio of the retardation film over time due to the influence of temperature and humidity is greatly generated in the stretching direction, the shrinkage ratio can be reduced by setting the stretching ratio to a certain level or less. In addition to obtaining the effect of improving the viewing angle characteristics and the effect of reducing the shrinkage rate due to the expression of such in-plane retardation R0, the excessive expression of the thickness direction retardation Rth is suppressed, and the field of view of the liquid crystal display device Since the angular characteristics can be further improved, the draw ratio is finally 10% (1.10 times) to 40% in the width direction (lateral direction) or the conveyance direction (longitudinal direction). 1.40 times) is more preferable.

  Thus, another embodiment of the present invention is a transverse electric field mode type liquid crystal display device in which a retardation film is uniaxially stretched in the transport direction at a stretch ratio of 1.10 to 1.40.

  The web stretching temperature is preferably 120 ° C. to 200 ° C., more preferably 150 ° C. to 200 ° C., and even more preferably 150 ° C. to 190 ° C.

  The residual solvent of the stretched web is preferably 20% by mass or less, and preferably 15% by mass or less.

  The method of stretching the web is not particularly limited, and a method in which a difference in peripheral speed is applied to a plurality of rolls and the roll is stretched in the longitudinal direction using the difference in the peripheral speed of the roll (roll stretching method). And extend the gap between clips and pins in the conveyance direction (vertical direction) and extend in the conveyance direction (vertical direction), or widen in the width (transverse) direction and extend in the width (transverse) direction. Or a method of stretching in the transport direction and the width direction (both longitudinal and lateral directions) and stretching in the transport direction and the width direction (both longitudinal and lateral directions) (tenter stretching method). Among these, it is preferable to use a roll stretching method. These stretching methods may be combined.

  In the tenter stretching method, the clip portion is preferably driven by a linear drive method. This is because the movement of the clip portion is smooth, so that it is easy to stretch and the risk of web breakage can be reduced.

  Web width retention and transverse stretching can be performed by a tenter method. The tenter method may be a pin tenter method or a clip tenter method.

  The drying step may be further provided after the stretching step. The retardation film that has undergone the drying step or the stretching step is then wound up.

  The width of the retardation film is preferably 1.0 to 3.0 m. A retardation film having such a width is used to produce a large number of polarizing plates from a single film when producing a relatively small polarizing plate for use in portable devices such as tablet-type display devices and smartphones. Is suitable.

(Film characteristics)
<Film thickness>
The thickness of the retardation film is not particularly limited, but is preferably 100 to 200 μm. When the film thickness is 100 μm or more, a retardation film having in-plane retardation R0 and thickness direction retardation Rth that sufficiently perform optical compensation of a transverse electric field mode type liquid crystal display device can be produced at a low draw ratio. Accordingly, the shrinkage of the film is suppressed, and the shrinkage rate of the film can be reduced. Therefore, the effect of suppressing display unevenness when the temperature and humidity environment of the liquid crystal display device is changed due to the shrinkage of the film is enhanced. Further, when the film thickness is 100 to 200 μm, the in-plane retardation R0 and the thickness direction retardation Rth can be adjusted to a range in which the viewing angle characteristics of the liquid crystal display device are further improved.

  From this, as another form of this invention, it is a horizontal electric field mode type liquid crystal display device whose film thickness of a phase difference film is 100-200 micrometers. From the viewpoint of achieving both the effect of improving the viewing angle characteristics and the effect of reducing the shrinkage rate, the film thickness is more preferably 110 μm to 180 μm, further preferably 120 μm to 160 μm, and particularly preferably 125 μm to 150 μm.

<In-plane retardation R0, thickness direction retardation Rth>
The retardation film has an in-plane retardation R0 represented by the following formula (I) of 100 to 270 nm and the following formula (II) with respect to light having a wavelength of 590 nm in an environment of 23 ° C. and 55% RH. The thickness direction retardation Rth is -30 to 30 nm.

Formula (I) R0 = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(However, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the film, ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film, nz represents the refractive index in the thickness direction z of the film, and d (nm) represents the thickness of the film).

  For the measurement of the in-plane retardation R0 and the thickness direction retardation Rth described above, an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) was used, and the wavelength was 23 ° C. and 55% RH. Is obtained by performing a three-dimensional refractive index measurement at 590 nm and obtaining refractive indexes nx, ny and nz.

  When the in-plane retardation R0 is 100 to 270 nm or the thickness direction retardation Rth is outside the range of −30 to 30 nm, the optical compensation of the lateral electric field mode type liquid crystal display device is not sufficiently performed and the viewing angle is narrowed. . In order to solve such a problem, the in-plane retardation R0 and the thickness direction retardation Rth are within the above ranges. From the viewpoint of further improving the viewing angle characteristics, R0 is preferably 160 to 270 nm, and more preferably 220 to 270 nm. From the same viewpoint, Rth is preferably −29 to 29 nm, more preferably −15 to 15 nm.

  In-plane retardation R0 and thickness direction retardation Rth are the types of cellulose acylate having an aromatic acyl group to be used, the amount of additive to be used if necessary, the film thickness, the stretching temperature, the stretching ratio, etc. It can be controlled according to conditions and the like.

  From the viewpoint of optical compensation of the transverse electric field mode type liquid crystal display device, in the polarizing plate state, the retardation film has the absorption axis direction of the polarizer orthogonal to the slow axis direction of the retardation film, and the polarizer It is preferable that the transmission axis direction and the slow axis direction of the retardation film are arranged in parallel.

  In addition, from the viewpoint of optical compensation of the transverse electric field mode type liquid crystal display device, the retardation film includes an orientation direction of liquid crystal molecules in a no voltage application state in the transverse electric field mode type liquid crystal cell, Are preferably arranged in parallel.

<Shrinkage factor>
The retardation film has a shrinkage ratio measured by the following method B of 0.10 to 1.00%.

[Method B]
Measure the shrinkage rate in the two directions, the slow axis direction and the direction perpendicular to the slow axis direction, measured before and after the retardation film at 100 ° C. in an environment of 80 ° C. and 90% relative humidity. Is the shrinkage rate.

  For the measurement of the retardation axis direction of the retardation film of the present invention, an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) is used simultaneously with the measurement of the in-plane retardation R0 and the thickness direction retardation Rth. Can be done.

  Then, the shrinkage rate in the slow axis direction of the retardation film and the direction perpendicular to the slow axis direction before 100 hours of aging at 80 ° C. and 90% relative humidity are measured. The shrinkage rate can be determined by measuring the distance between two specific points when placed in an environment of 80 ° C. and 90% relative humidity and after 100 hours and left to stand in an environment of 23 ° C. and 55% relative humidity for 1 hour. Further, in accordance with JIS K6911, a heat shrinkage measuring device Model No. It can be measured using EGTP-501 (manufactured by Eager Corporation). Details of the measurement method are described in the examples.

  Method B, which is a method for measuring the shrinkage rate of the retardation film, is different from Method A, which is a method for measuring the shrinkage rate of the polarizing plate protective films F1 and F4, in determining the measurement direction.

  The inventors of the present invention have confirmed the relationship between the shrinkage ratio of the retardation film obtained by the method B and the display unevenness of the horizontal electric field mode type liquid crystal display device. This is a method for measuring a retardation film.

  The reason for the high correlation between the shrinkage rate of Method B and the display unevenness of the horizontal electric field mode type liquid crystal display device is estimated as follows.

  The display unevenness of the transverse electric field mode type liquid crystal display device is considered to have the highest correlation with the shrinkage rate in the direction showing the largest shrinkage rate in the retardation film.

  In general, a film generated with the passage of time in a high-temperature and high-humidity environment has the largest shrinkage rate in the direction of the highest orientation in the plane.

  Here, when the retardation film has positive birefringence, the slow axis direction is considered to be the direction with the highest orientation in the plane, and when the retardation film has negative birefringence, the retardation film is slow. It can be considered that the direction orthogonal to the phase axis direction is the highest orientation in the in-plane direction. Therefore, it can be considered that the direction with the highest orientation in the plane of the retardation film is either the slow axis direction or the direction perpendicular to the slow axis direction. From this, the reason for the high correlation between the shrinkage rate of Method B and the display unevenness of the transverse electric field mode type liquid crystal display device is that the shrinkage rate in two directions, ie, the slow axis direction of the retardation film and the direction perpendicular to the slow axis direction. It can be considered that by measuring and selecting the larger value, the shrinkage rate in the direction in which the shrinkage rate that is the highest orientation in the film plane is the largest is obtained. Note that the above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention.

  When the shrinkage ratio of the retardation film is less than 0.10%, it is a case where hydrophobicity is imparted to the film, and the drying property is lowered during adhesion (water glue adhesion) to the polarizer with a water-soluble adhesive. Therefore, productivity is reduced. Further, when the shrinkage rate of the retardation film exceeds 1.0%, display unevenness when the temperature and humidity environment of the liquid crystal display device changes due to the shrinkage of the film becomes remarkable. In order to solve such a problem, the shrinkage rate of the retardation film is set in the above range.

  From the viewpoint of further suppressing display unevenness, the shrinkage rate is preferably 0.10 to 0.90%, more preferably 0.10 to 0.80%, and 0.10 to 0.70%. More preferably it is.

  The shrinkage rate can be controlled by the production conditions such as the type of cellulose acylate having an aromatic acyl group to be used, the amount of additive to be used, the film thickness, the stretching temperature, and the stretching ratio, if necessary. Moreover, since the retardation film which concerns on one form of this invention has the tendency for shrinkage | contraction rate to also become small by making the below-mentioned moisture permeability small, it is also preferable to set it as the design which reduces a moisture permeability.

<Moisture permeability>
The moisture permeability of the retardation film can be measured according to a moisture permeability test (cup method) of JIS Z0208. In the present application, the moisture permeability uses a value converted to a film thickness of 40 μm. Details of the measurement method are described in the examples.

The retardation film is preferably moisture permeability of the film thickness 40μm conversion is ^{30~1250 (g / m 2 / 24h} ). When the moisture permeability is 30 (g / m ² / 24h) or more, the drying time of water-adhesive adhesion (water glue adhesion) to the polarizer can be shortened. When the moisture permeability is 1250 (g / m ² / 24h) or less, the effect of temperature and humidity can be reduced and the film shrinkage over time can be reduced by hydrophobizing the film. The effect of suppressing display unevenness when the temperature and humidity environment of the liquid crystal display device is changed is further enhanced. From the viewpoint of suppression of additional display unevenness, the moisture permeability is more preferably ^{30~1100 (g / m 2 / 24h} ), more preferably from ^{30~800 (g / m 2 / 24h} ).

  The moisture permeability can be controlled by the type of cellulose acylate having an aromatic acyl group to be used, the amount of additive to be used if necessary, the film thickness, and the like.

(Isotropic film)
The isotropic film used for the films F2 and F3 that are not retardation films is a film that is used in combination with the retardation film as necessary in order to exhibit the optical compensation effect of the retardation film.

  The isotropic film is preferably a film that also functions as a polarizing plate protective film. In that case, in addition to the films F2 and F3 and the polarizing plate protective films F1 and F4, a further polarizing plate protective film is used. Need not be prepared separately. Thus, the thickness of the liquid crystal display device can be reduced and the manufacturing process can be simplified.

  The isotropic film is not particularly limited as long as it satisfies the in-plane retardation R0, the thickness direction retardation Rth, and the shrinkage rate of the isotropic film described later.

  As the isotropic film, it is preferable to use a thermoplastic resin film that is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like. The thermoplastic resin used for the thermoplastic resin film is not particularly limited. For example, cellulose resin, (meth) acrylic resin such as polymethyl methacrylate (PMMA), cycloolefin polymer (COP), cycloolefin copolymer And cyclic polyolefin resins such as (COC). Two or more of these thermoplastic resins may be used. Among these, cellulose triacetate, which is a cellulose resin, and COP, which is a cyclic olefin resin, are preferable from the viewpoints of transparency and optical properties.

  Moreover, an isotropic film may contain the additive which can be added to the above-mentioned retardation film.

  A commercially available film may be used as the isotropic film, and as a commercially available product, for example, Zero Tack manufactured by Konica Minolta Co., Ltd., Z-tack manufactured by Fuji Film Co., Ltd., or the like can be used.

  An isotropic film is manufactured by a well-known method. The production method is not particularly limited, and a film produced by a solution casting method or a film produced by a melt casting method can be preferably used.

  The isotropic film may have a known functional layer as long as the effects of the present invention are not impaired.

(Film characteristics)
<Film thickness>
The film thickness of the isotropic film is not particularly limited, but is preferably 15 to 60 μm, and more preferably 30 to 50 μm.

<In-plane retardation R0, thickness direction retardation Rth>
The isotropic film has an in-plane retardation R0 represented by the following formula (I) of 0 to 5 nm, represented by the following formula (II) with respect to light having a wavelength of 590 nm in an environment of 23 ° C. and 55% RH. The thickness direction retardation Rth is -10 to 10 nm.

Formula (I) R0 = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(However, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the film, ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film, nz represents the refractive index in the thickness direction z of the film, and d (nm) represents the thickness of the film).

  For the measurement of the in-plane retardation R0 and the thickness direction retardation Rth described above, an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) was used, and the wavelength was 23 ° C. and 55% RH. Is obtained by performing a three-dimensional refractive index measurement at 590 nm and obtaining refractive indexes nx, ny and nz.

  When the in-plane retardation R0 is 0 to 5 nm or the thickness direction retardation Rth is outside the range of −10 to 10 nm, the optical compensation of the lateral electric field mode type liquid crystal display device is not sufficient, and the viewing angle is narrowed. . In order to solve such a problem, the in-plane retardation R0 and the thickness direction retardation Rth are within the above ranges. From the viewpoint of further improving the viewing angle characteristics, R0 is preferably 0 to 3 nm, and more preferably 0 to 2 nm. From the same viewpoint, Rth is preferably -7 to 7 nm, and more preferably -5 to 5 nm.

  In-plane retardation R0 and thickness direction retardation Rth are the production conditions such as the kind of film forming material such as thermoplastic resin used, the amount of additive used, film thickness, stretching temperature, and stretching ratio, if necessary. Etc. can be controlled.

<Shrinkage factor>
The isotropic film has a shrinkage ratio measured by the following method A of 0.01 to 1.00%.

[Method A]
The film viewed from the position in the polarizing plate in a 90% relative humidity 90% environment for about 100 hours, parallel to the absorption axis direction of the polarizer, the direction orthogonal to the absorption axis direction of the polarizer, the absorption axis of the polarizer Measure the shrinkage in 4 directions, 45 ° from the direction and 135 ° from the absorption axis direction of the polarizer, and set the largest value as the shrinkage.

  The shrinkage rate can be determined by measuring the distance between two specific points when placed in an environment of 80 ° C. and 90% relative humidity and after 100 hours and left in an environment of 23 ° C. and 55% relative humidity for 1 hour. Further, in accordance with JIS K6911, a heat shrinkage measuring device Model No. It can be measured using EGTP-501 (manufactured by Eager Corporation). Details of the measurement method are described in the examples.

  The inventors of the present invention have confirmed the relationship between the shrinkage of the isotropic film obtained by the method A and the display unevenness of the transverse electric field mode type liquid crystal display device. This is a method for measuring the shrinkage rate of an isotropic film.

  It is presumed that the reason why the correlation between the shrinkage rate of Method A and the display unevenness of the horizontal electric field mode type liquid crystal display device is high is the same as that of the polarizing plate protective films F1 and F4.

  When the shrinkage of the isotropic film is less than 0.01%, it is a case where hydrophobicity is imparted to the film, and there is a drying property when adhering to the polarizer with a water-soluble adhesive (water glue adhesion). Productivity decreases due to lowering. Further, when the shrinkage rate of the isotropic film exceeds 1.0%, display unevenness when the temperature and humidity environment of the liquid crystal display device changes due to the shrinkage of the film becomes remarkable. In order to solve such a problem, the shrinkage rate of the retardation film is set in the above range.

  From the viewpoint of further suppressing display unevenness, the shrinkage rate is preferably 0.01 to 0.90%, more preferably 0.01 to 0.80%, and 0.01 to 0.70%. More preferably it is.

  The shrinkage rate is controlled by a known method such as the type of film forming material such as a thermoplastic resin to be used, the amount of additive to be used if necessary, the film thickness, the stretching temperature, and the production conditions such as the stretching ratio. Can do. Moreover, since the isotropic film which concerns on one form of this invention has the tendency for a shrinkage | contraction rate to also become small by making the water vapor transmission rate mentioned later small, it is also preferable to set it as the design which reduces water vapor transmission rate.

<Moisture permeability>
The moisture permeability of the isotropic film can be measured according to a moisture permeability test (cup method) of JIS Z0208. In the present application, the moisture permeability uses a value converted to a film thickness of 40 μm. Details of the measurement method are described in the examples.

Isotropic film is preferably moisture permeability of the film thickness 40μm conversion is ^{0.1~1250 (g / m 2 / 24h} ). If the moisture permeability is at 0.1 (g / m 2 / 24h ) or higher can shorten the drying time of the adhesive by water-soluble adhesive between the polarizer (Mizunori adhesive). When the moisture permeability is 1250 (g / m ² / 24h) or less, the effect of temperature and humidity can be reduced and the film shrinkage over time can be reduced by hydrophobizing the film. The effect of suppressing display unevenness when the temperature and humidity environment of the liquid crystal display device is changed is further enhanced. From the viewpoint of suppression of additional display unevenness, the moisture permeability is more preferably ^{0.1~1100 (g / m 2 / 24h} ), more preferably from ^{0.1~800 (g / m 2 / 24h} ).

(Production method of polarizing plate)
The polarizing plate according to the present invention can be produced by a general method.

  Hereinafter, as an example, a case where a polarizing plate protective film, a polarizer, and a retardation film or an isotropic film are directly bonded using an adhesive will be described.

  The retardation film or isotropic film according to the present invention is bonded to at least one surface of the polarizer using an adhesive, and the polarizing plate protective film is bonded to the other surface using an adhesive. It is preferable to combine them.

  Although it does not restrict | limit especially as an adhesive agent, For example, a polyvinyl alcohol-type adhesive agent, an acrylic adhesive, a urethane type adhesive agent etc. are mentioned.

  The polarizing plate protective film, the polarizer, and the retardation film or isotropic film may be subjected to surface modification treatment before being bonded. The surface modification treatment is not particularly limited, and examples thereof include corona treatment, plasma treatment, and saponification treatment.

  Here, in the case where the retardation film or isotropic film or the polarizing plate protective film is a cellulose acylate film, at least the surface on the polarizer side of the film is subjected to alkali saponification treatment, and a polyvinyl alcohol-based adhesive is adhered to the surface of the polarizer. It is preferable to bond using an agent. Moreover, when an isotropic film or a polarizing plate protective film is films other than a cellulose acylate film, it is preferable to bond on the surface of a polarizer using an acrylic type or a urethane type adhesive agent.

  Bonding of the polarizing plate protective film, the polarizer, and the retardation film or isotropic film can be performed by a roll laminator or the like.

[Backlight]
A backlight is arrange | positioned facing the polarizing plate protective film F4 of a 2nd polarizing plate. An arbitrary optical member may be disposed between the backlight and the polarizing plate protective film F4.

  The backlight may be a sidelight (edge light) type surface light source in which a known light source is disposed on the side surface of the light guide plate, or a direct type surface light source in which a known light source is arranged under the diffusion plate. Examples of known light sources include cold cathode fluorescent lamps (CCFL), hot cathode fluorescent lamps (HCFL), external electrode fluorescent lamps (EEFL), flat fluorescent lamps (FFL), light emitting diode elements (LEDs), organic electroluminescent elements (OLEDs). ) Is included. Among these, from the viewpoint of reducing the power consumption of the liquid crystal display device, a backlight using an LED as a light source (LED backlight) is preferable.

[Usage]
The application of the horizontal electric field mode liquid crystal display device according to one embodiment of the present invention is not particularly limited, but it is thin and lightweight, has a wide viewing angle, and is excellent in durability against temperature and humidity changes. It can be preferably used for portable devices such as tablet display devices and smartphones.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

[Synthesis of cellulose acylate having an aromatic acyl group]
Cellulose acylates having an aromatic acyl group used for the production of retardation films used as the films F2 and F3 were synthesized as follows.

(Synthesis Example 1: Synthesis of cellulose acylate C1)
200 g of acetyl cellulose having a substitution degree of 0.5, 2 L of acetone and 120 mL of pyridine were weighed into a 5 L three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel, and stirred at room temperature. Benzyl chloride 172mL was dripped here slowly, and also it stirred at 60 degreeC after dripping for 5 hours. After the reaction, the mixture was allowed to cool to room temperature, and the reaction solution was poured into 10 L of methanol with vigorous stirring, whereby a white solid was precipitated. The white solid was filtered off by suction filtration and washed with a large amount of methanol three times. The obtained white solid was dried at 60 ° C. overnight and then vacuum dried at 90 ° C. for 6 hours to obtain 220 g of the objective cellulose acylate C1 as a white powder. The viscosity average degree of polymerization was 270.

(Synthesis Example 2: Synthesis of cellulose acylate C2)
250 g of the target cellulose acylate C2 was obtained as a white powder in the same manner as in the synthesis of the cellulose acylate C1 except that the substitution degree of acetylcellulose was changed to 1.0. The viscosity average degree of polymerization was 275.

(Synthesis Example 3: Synthesis of cellulose acylate C3)
260 g of the desired cellulose acylate C3 was obtained as a white powder in the same manner as in the synthesis of the cellulose acylate C1 except that the substitution degree of acetyl cellulose was changed to 0.5 and the substitution degree was 1.7. The viscosity average degree of polymerization was 245.

(Synthesis Example 4: Synthesis of cellulose acylate C4)
270 g of the target cellulose acylate C4 was obtained as a white powder in the same manner as in the synthesis of the cellulose acylate C1, except that the acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 2.0. The viscosity average degree of polymerization was 240.

(Synthesis Example 5: Synthesis of cellulose acylate C5)
280 g of the target cellulose acylate C5 was obtained as white powder in the same manner as in the production of the cellulose acylate C1 except that the substitution degree of acetylcellulose was changed to 0.5. The viscosity average degree of polymerization was 252.

(Synthesis Example 6: Synthesis of cellulose acylate C6)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 192 mL, 172 mL of benzoyl chloride was changed to 275 mL, and acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.0. 265 g of rate C6 was obtained as a white powder. The viscosity average degree of polymerization was 255.

(Synthesis Example 7: Synthesis of cellulose acylate C7)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 192 mL, 172 mL of benzoyl chloride was changed to 275 mL, and acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.7. 275 g of rate C7 was obtained as a white powder. The viscosity average degree of polymerization was 250.

(Synthesis Example 8: Synthesis of cellulose acylate C8)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 192 mL, 172 mL of benzoyl chloride was changed to 275 mL, and acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 2.0. 285 g of rate C8 was obtained as a white powder. The viscosity average degree of polymerization was 270.

(Synthesis Example 9: Synthesis of cellulose acylate C9)
In the production of the above cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 192 mL, 172 mL of benzoyl chloride was changed to 275 mL, and acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 2.2. 295 g of rate C9 was obtained as a white powder. The viscosity average degree of polymerization was 255.

(Synthesis Example 10: Synthesis of cellulose acylate C10)
The target cellulose acylate was prepared in the same manner as in the production of the exemplified compound C1, except that 120 mL of pyridine was changed to 240 mL, 172 mL of benzoyl chloride was changed to 344 mL, and acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.5. 310 g of C10 was obtained as a white powder. The viscosity average degree of polymerization was 230.

(Synthesis Example 11: Synthesis of cellulose acylate C11)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 240 mL, 172 mL of benzoyl chloride was changed to 344 mL, and acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.7. 320 g of rate C11 was obtained as a white powder. The viscosity average degree of polymerization was 235.

(Synthesis Example 12: Synthesis of cellulose acylate C12)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 240 mL, 172 mL of benzoyl chloride was changed to 344 mL, and acetylcellulose having a substitution degree of 0.5 was changed to a substitution degree of 2.0. 330 g of rate C12 was obtained as a white powder. The viscosity average degree of polymerization was 232.

(Synthesis Example 13: Synthesis of cellulose acylate C13)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 360 mL, 172 mL of benzoyl chloride was changed to 516 mL, and acetylcellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.0. 340 g of rate C13 was obtained as a white powder. The viscosity average degree of polymerization was 210.

(Synthesis Example 14: Synthesis of cellulose acylate C14)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 360 mL, 172 mL of benzoyl chloride was changed to 516 mL, and acetylcellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.5. 350 g of rate C14 was obtained as a white powder. The viscosity average degree of polymerization was 215.

(Synthesis Example 15: Synthesis of cellulose acylate C15)
345 g of the target cellulose acylate C14 was obtained as a white powder in the same manner as in the production of cellulose acylate C1 except that 120 mL of pyridine was changed to 480 mL and 172 mL of benzoyl chloride was changed to 688 mL. The viscosity average degree of polymerization was 230.

(Synthesis Example 16: Synthesis of cellulose acylate C16)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 480 mL, 172 mL of benzoyl chloride was changed to 688 mL, and acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.0. 355 g of rate C16 was obtained as a white powder. The viscosity average degree of polymerization was 205.

(Synthesis Example 17: Synthesis of cellulose acylate C17)
In the production of the above cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 96 mL, 172 mL of benzoyl chloride was changed to 138 mL, and acetyl cellulose having a substitution degree of 0.5 was changed to a substitution degree of 0.4. 210 g of rate C17 was obtained as a white powder. The viscosity average degree of polymerization was 255.

(Synthesis Example 18: Synthesis of cellulose acylate C18)
In the production of the cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 24 mL, 172 mL of benzoyl chloride was changed to 35 mL, and acetylcellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.7. 185 g of rate C18 was obtained as a white powder. The viscosity average degree of polymerization was 260.

(Synthesis Example 19: Synthesis of cellulose acylate C19)
In the previous production of cellulose acylate C1, the target cellulose acylate was similarly prepared except that 120 mL of pyridine was changed to 72 mL, 172 mL of benzoyl chloride was changed to 104 mL, and acetylcellulose having a substitution degree of 0.5 was changed to a substitution degree of 1.7. 195 g of rate C19 was obtained as a white powder. The viscosity average degree of polymerization was 250.

(Synthesis Example 20: Synthesis of Comparative Example C20)
As cellulose acylate C20, Ca394-60S (acetyl substitution degree 2.4, total substitution degree 2.4) manufactured by Eastman Chemical Co., Ltd. was used.

(Measurement of substituent, degree of substitution and weight average molecular weight)
The substitution degree of each substituent of the cellulose acylate C1 to C20 is determined by ¹ H-NMR using the method described in Cellulose Communication 6,73-79 (1999) and Chirality 12 (9), 670-674. And ¹³ C-NMR.

  Moreover, the weight average molecular weight (Mw) of the said cellulose acylate C1-C20 was measured on condition of the following using gel permeation chromatography (GPC).

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves using 13 samples are used. Thirteen samples are used at approximately equal intervals.

  The details of cellulose acylates C1 to C20 are shown in Table 1 below.

[Production of retardation film]
The retardation films 101 to 126 used as the retardation films F2 and F3 were produced as follows.

(Preparation of retardation film 101)
11 parts by mass of fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) and 89 parts by mass of ethanol were stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to obtain a fine particle dispersion. Next, 99 parts by mass of methylene chloride was charged into the dissolution tank, and 5 parts by mass of the fine particle dispersion was slowly added while stirring sufficiently. Thereafter, the obtained solution is dispersed by an attritor so that the particle size of the secondary particles becomes a predetermined size, and then filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. Got.

Using the obtained fine particle addition liquid, a dope liquid having the composition shown below was prepared.
First, 340 parts by mass of methylene chloride and 64 parts by mass of ethanol were charged into a pressure dissolution tank. In these solvents, 100 parts by mass of cellulose acylate C1 (acetyl group substitution degree 0.5, benzoyl group substitution degree 0.5, total substitution degree 1.0) and 1 part by mass of the fine particle additive were further stirred. Then, the mixture was stirred under heating and completely dissolved. The obtained solution was Azumi Filter Paper No. It filtered using 244 and the dope liquid shown by the following composition was prepared.

<Composition of dope solution>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acylate C1 (acetyl group substitution degree 0.5, benzoyl group substitution degree 0.5, total substitution degree 1.0) 100 parts by mass Fine particle additive solution 1 part by mass The liquid was uniformly cast on a stainless belt support of an endless belt casting apparatus under the condition of a dope liquid temperature of 33 ° C. The surface temperature of the stainless steel belt support was 30 ° C. On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film was 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m.

  Next, while applying heat at 170 ° C. to the peeled optical film, a difference in peripheral speed is applied to a plurality of rolls, and the difference between the peripheral speeds of the rolls is used to make 30% in the conveying direction (longitudinal direction / longitudinal direction) .3 times) free end uniaxial stretching. The residual solvent at the start of stretching was 15%. Then, it dried at 130 degreeC and obtained the optical film with a dry film thickness of 138 micrometers.

(Production of retardation films 102 to 126)
In the production of the retardation film 101, retardation films 102 to 126 were produced in the same manner except that the type of cellulose acylate, the draw ratio, and the film thickness of the produced film were changed as shown in Table 2 below.

[Preparation of polarizing plate protective film]
The following commercially available films A and B (hereinafter also referred to as polarizing plate protective films A and B) were prepared as the films used as the polarizing plate protective films F1 and F4.

(Film A)
Polyethylene terephthalate (PET) film (Toyobo Co., Ltd., Toyobo Ester Film E7002, 40 μm)
(Film B)
Triacetyl cellulose (TAC) film (Konica Minolta, Konica Minolta KC4UY, 40 μm)
[Preparation of isotropic film]
The following commercially available films C (hereinafter also referred to as isotropic films C) were prepared as isotropic films used as the films F2 and F3.

(Film C)
Triacetylcellulose (TAC) film (Konica Minolta, Zerotack KC4CZ, 40 μm)
[Evaluation of retardation film, isotropic film and polarizing plate protective film]
(Film thickness)
The film thickness of the center part of the obtained retardation films 101-126 was measured using a contact-type film thickness meter (Micrometer Minicom M manufactured by ACCRETECH (Tokyo Seimitsu Co., Ltd.)).

(In-plane retardation R0 and thickness direction retardation Rth)
The retardation value of the center part of the width direction of the obtained retardation films 101-126 and the isotropic film C was measured. For measurement, an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) was used, and humidity was adjusted for 2 hours in an environment of 23 ° C. and 55% RH. Then, the measured value was substituted into the following formula (I) and the in-plane retardation R0 was substituted into the following formula (II) to obtain the thickness direction retardation Rth.

Formula (I) R0 = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(However, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the film, ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film, nz represents the refractive index in the thickness direction z of the film, and d (nm) represents the thickness of the film).

  The values of the in-plane retardation R0 and the thickness direction retardation Rth of the retardation films 101 to 126 are shown in Table 2 below.

  The in-plane retardation R0 of the isotropic film C was 1 nm, and the thickness direction retardation Rth was 1 nm.

(Durability test (shrinkage))
The shrinkage rates of the polarizing plate protective films A and B and the isotropic film C were determined by the following method A, and the shrinkage rates of the retardation films 101 to 126 were determined by the following method B.

  Specifically, first, the shrinkage rate was obtained by measuring the shrinkage rate in a specific direction and then selecting the maximum shrinkage rate from the obtained shrinkage rates in a plurality of specific directions.

The shrinkage rate in a specific direction was measured using a thermal shrinkage measuring device (manufactured by Eager Corporation) Model No. EGTP-501). The shrinkage rate in a specific direction is the length L ₀ in the vertical direction of the sample before the test after standing for 1 hour in an environment of 23 ° C. and 55% relative humidity using a sample of 70 mm long × 90 mm wide, From the value of the length L ₁ in the longitudinal direction of the sample after the test after standing at 80 ° C. and 90 RH% for 100 hours and then standing at 23 ° C. and 55% relative humidity for 1 hour, It calculated | required according to following formula (V).

Formula (V) Shrinkage rate = (L ₀ −L ₁ ) / L ₀ × 100 (%)
<Shrinkage rate of polarizing plate protective film and isotropic film>
The shrinkage rates of the polarizing plate protective films A and B and the isotropic film C were obtained from the following method A.

[Method A]
The film viewed from the position in the polarizing plate in a 90% relative humidity 90% environment for about 100 hours, parallel to the absorption axis direction of the polarizer, the direction orthogonal to the absorption axis direction of the polarizer, the absorption axis of the polarizer Measure the shrinkage in 4 directions, 45 ° from the direction and 135 ° from the absorption axis direction of the polarizer, and set the largest value as the shrinkage.

  Here, in this example, as described later, in the production of the first polarizing plate and the second polarizing plate, the longitudinal direction of the polarizing plate protective films A and B and the isotropic film C and the polarizer described later are used. Are pasted so that their longitudinal directions, that is, the absorption axis directions coincide. Thus, the longitudinal direction of the polarizing plate protective films A and B and the isotropic film C is parallel to the absorption axis direction of the polarizer. The directions of 45 ° and 135 ° from the absorption axis direction of the polarizer represent the 45 ° direction and the 135 ° direction when the absorption axis of the polarizer is 0 °.

  Values of shrinkage rates of the polarizing plate protective films A and B are shown in Table 2 below.

  The shrinkage ratio of the isotropic film C was 0.1%.

<Shrinkage rate of retardation film>
The shrinkage ratio of the retardation films 101 to 126 was determined from the following method B.

[Method B]
Measure the shrinkage rate in the two directions, the slow axis direction and the direction perpendicular to the slow axis direction, measured before and after the retardation film at 100 ° C. in an environment of 80 ° C. and 90% relative humidity. Is the shrinkage rate.

  Here, the measurement in the slow axis direction was performed using the automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) simultaneously with the measurement of the in-plane retardation R0 and the thickness direction retardation Rth.

  Note that the in-plane slow axis direction of the films 101 to 126 is the width direction of the film, which is a direction orthogonal to the stretching direction in the films 101 to 119 and 124 to 126, and is stretched in the films 120 to 123. The longitudinal direction of the film was parallel to the direction.

  The shrinkage rates of the retardation films 101 to 126 are shown in Table 2 below.

<Moisture permeability>
The measurement of moisture permeability of the polarizing plate protective films A and B, the isotropic film C, and the obtained retardation films 101 to 126 was performed according to the moisture permeability test (cup method) of JIS Z0208. A sample cut to a diameter of 60 mm is set in a moisture permeable cup containing about 15 g of calcium chloride, placed in a thermostatic oven at 40 ° C. and 90% relative humidity, and the mass increase of calcium chloride before and after being left for 24 hours is measured. The moisture permeability (g / m ² / 24h) was determined. Furthermore, from the product of the obtained moisture permeability and the film thickness ratio (film thickness (μm) / 40 (μm)) of the film thickness (μm) to the converted film thickness 40 μm, the film thickness 40 μm equivalent moisture permeability (g / M ² / 24h).

  The results of the polarizing plate protective films A and B and the retardation films 101 to 126 are shown in Table 2 below.

Thickness 40μm conversion moisture permeability of the isotropic film C was ^{200 (g / m 2 / 24h} ).

[Production of first polarizing plate and second polarizing plate]
(Preparation of polarizing plate 201)
A polarizing plate 201 used for the first polarizing plate and the second polarizing plate was produced by the following method.

  A 50 μm thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution consisting of 0.075 parts by mass of iodine, 5 parts by mass of potassium iodide, and 100 parts by mass of water, and then from 6 parts by mass of potassium iodide, 7.5 parts by mass of boric acid, and 100 parts by mass of water. It was immersed in an aqueous solution at 68 ° C. This was washed with water and dried to obtain a 10 μm polarizer.

  Next, the polarizer, the retardation film 101 disposed on the one surface side of the polarizer, and the film A disposed on the other surface side of the polarizer according to the following steps 1 to 5, the longitudinal direction of the polarizer and the film The polarizing plates were produced by pasting together so that the longitudinal directions of the two were aligned. The longitudinal direction of the polarizer coincides with the absorption axis direction of the polarizer. Further, the absorption axis direction and the transmission axis direction of the polarizer are orthogonal to each other.

Step 1: The film 101 as a retardation film is immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to saponify the side to be bonded to the polarizer;
Step 2: The polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds;
Step 3: Excess adhesive on one side adhering to the polarizer in Step 2 was gently wiped off and placed on the retardation film 101 processed in Step 1;
Step 4: After lightly wiping off the adhesive adhering to the polarizer-side surface of the laminate of the film 101 and the polarizer laminated in Step 3, the polarizing plate protective film A is stacked via an acrylic adhesive pressure 20-30 N / cm ^2, the conveyance speed was pasted at approximately 2m / min;
Step 5: A sample obtained by bonding the polarizer, the retardation film 101 and the polarizing plate protective film A prepared in Step 4 in a dryer at 80 ° C. was dried for 2 minutes to prepare a polarizing plate 201.

(Production of polarizing plates 202-219, 224-226, 228)
In the production of the polarizing plate 201, polarizing plates 202 to 219, 224 to 226, and 228 were produced in the same manner except that the type of retardation film and the type of polarizer were changed as shown in Table 2 below.

  Further, the 30 μm polarizer in the polarizing plate 226 is obtained in the same manner as in the case of obtaining the 10 μm polarizer except that a 150 μm thick polyvinyl alcohol film is used instead of the 50 μm thick polyvinyl alcohol film. It was.

(Preparation of polarizing plates 220 to 223)
The polarizer produced in the polarizing plate 201 is cut out, and the retardation films 120 to 123 cut out after saponification treatment in the same manner as in Step 1 are performed on one side of the polarizer, respectively, in the absorption axis direction of the polarizer and the film before cutting out. The laminate was bonded to one surface of the polarizer using a polyvinyl alcohol adhesive so that the longitudinal direction of the polarizer was orthogonal. Furthermore, the polarizing plate protective film A cut out on the polarizer-side surface of each laminated body of the laminated films 120 to 123 and the polarizer is aligned with the absorption axis direction of the polarizer and the longitudinal direction of the film before cutting out. It was pasted using an acrylic adhesive. Then, each sample which bonded the polarizer, retardation film 120-123, and the polarizing plate protective film A was dried similarly to the process 5, and the polarizing plates 220-223 were produced.

(Preparation of polarizing plate 227)
In the production of the polarizing plate 201, the retardation film 104 was used instead of the retardation film 101, and the polarizing plate protective film B was used instead of the polarizing plate protective film A. In the step 1, the polarizing plate protective film B The saponification treatment was also performed, the excess adhesive on both sides was lightly wiped off in Step 3, and the polyvinyl alcohol adhesive was wiped off in Step 4 without using an acrylic adhesive. A polarizing plate 227 was produced in the same manner except that the polarizing plate protective film B was laminated and bonded via a polyvinyl alcohol adhesive.

(Preparation of polarizing plate C)
A polarizing plate C was produced in the same manner as in the production of the polarizing plate 201 except that the retardation film 101 was changed to the isotropic film C.

(Preparation of polarizing plate C2)
In the production of the polarizing plate 227, a polarizing plate C2 was produced in the same manner except that the retardation film 104 was changed to the isotropic film C.

(Production of IPS liquid crystal display device)
[Example 1]
<Preparation of IPS liquid crystal cell 1>
In order to form a liquid crystal element pixel region as shown in FIG. 2 on a single glass substrate having a thickness of 0.2 mm, electrodes (8 and 9 in FIG. 2) are set so that the distance between adjacent electrodes is 20 μm. And a polyimide film as an alignment film thereon, and a rubbing treatment was performed in a direction 10 shown in FIG. A polyimide film was provided on one surface of a separately prepared glass substrate having a thickness of 0.2 mm, and a rubbing treatment was performed to obtain an alignment film. The two glass substrates are stacked and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 3.9 μm, and the rubbing direction of the two glass substrates is antiparallel. Next, a nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was sealed. The value of d · Δn of the liquid crystal layer was 300 nm. At this time, the alignment direction of the liquid crystal molecules in the IPS liquid crystal cell without applying voltage was perpendicular to the long side of the IPS liquid crystal cell (that is, the screen of the liquid crystal display device). In the IPS liquid crystal display device, the IPS liquid crystal cell 1 is arranged so that the substrate side having the electrodes faces the backlight side and the opposite substrate side faces the viewing side.

[Example 1]
Using an acrylic pressure-sensitive adhesive (highly transparent adhesive transfer tape (manufactured by 3M, product number 8172CL)), the surface of the polarizing plate C on the side of the isotropic film is placed on the substrate side having the electrodes of the IPS liquid crystal cell 1. The surface of the polarizing plate 201 on the phase difference film side was bonded to the surface of the substrate side opposite to the IPS type liquid crystal cell 1. Here, the absorption axis direction of the first polarizing plate (polarizer) is orthogonal to the alignment direction of the liquid crystal molecules when no voltage is applied in the IPS liquid crystal cell (that is, the absorption axis of the first polarizing plate (polarizer)). The direction is parallel to the long side of the screen of the IPS liquid crystal display device, and the absorption axis of the first polarizing plate (polarizer) is orthogonal to the absorption axis of the second polarizing plate (polarizer). Pasted.

  At this time, the polarizing plate arranged on the viewing side of the IPS type liquid crystal cell 1 becomes the first polarizing plate, and the polarizing plate arranged on the backlight side becomes the second polarizing plate. Here, the film F2 is the retardation film 101, and the film F3 is the isotropic film C.

  Furthermore, Xperia (registered trademark) Z2 D6502 (manufactured by Sony Mobile Communications Inc.), which is a portable device, was prepared. Then, the mounted liquid crystal cell, the two polarizing plates attached on both sides of the liquid crystal cell, the touch panel attached on the viewing side polarizing plate, and the cover glass attached on the touch panel are peeled off, respectively. I took it out.

  Then, the above-mentioned touch panel was removed with an acrylic adhesive on the polarizing plate protective film (polarizing plate protective film F1) of the polarizing plate 201 in the laminate composed of the polarizing plate 201, the IPS liquid crystal cell 1, and the polarizing plate C. Used for pasting. Furthermore, the cover glass was bonded onto the touch panel using an acrylic adhesive. As the cover glass, a cover glass having a thickness of 0.2 mm (G-Leaf (registered trademark) manufactured by Nippon Electric Glass Co., Ltd.) was used. Thus, the laminated body containing a cover glass, a touch panel, a 1st polarizing plate, an IPS type liquid crystal cell, and a 2nd polarizing plate was produced.

  Thereafter, a laminate including the cover glass, the touch panel, the first polarizing plate, the IPS liquid crystal cell, and the second polarizing plate is formed on the backlight of the portable device. The plate protective film (polarizing plate protective film F4) was disposed so as to face the backlight, and the liquid crystal display device 301 of Example 1 was produced.

[Examples 2 to 19, Comparative Examples 1 to 6, 8, and 10]
In Example 1, IPS type liquid crystal display devices 302 to 325 and 327 to 329 were manufactured in the same manner except that the type of polarizing plate having a retardation film was changed as shown in Table 2 below.

[Comparative Example 7]
In Example 4, a cover glass having a thickness of 0.05 mm (SPOOL (registered trademark) manufactured by Asahi Glass Co., Ltd.) was used instead of the 0.2 mm cover glass (G-Leaf (registered trademark) manufactured by Nippon Electric Glass Co., Ltd.). An IPS liquid crystal display device 326 was produced in the same manner except for the above.

[Comparative Example 9]
An IPS liquid crystal display device 328 was produced in the same manner as in Example 1, except that the polarizing plate 201 was changed to the polarizing plate 227 and the polarizing plate C was changed to the polarizing plate C2.

<Preparation of IPS mode liquid crystal cell 2>
An IPS mode liquid crystal cell 2 was produced in the same manner as in the above method except that the rubbing direction was reversed by 90 °. The value of d · Δn of the liquid crystal layer was 300 nm. At this time, the alignment direction of the liquid crystal molecules in the IPS type liquid crystal cell without applying voltage was parallel to the long side of the screen of the IPS type liquid crystal display device.

[Example 20]
In Example 7, using the IPS liquid crystal cell 2 instead of the IPS liquid crystal cell 1, the surface on the phase difference film side of the polarizing plate 207 is changed to the surface on the substrate side having the electrodes of the IPS liquid crystal cell 2. The surface of the C isotropic film side was bonded to the surface of the substrate side opposite to the IPS liquid crystal cell 2.

  Here, the absorption axis direction of the first polarizing plate (polarizer) is parallel to the alignment direction of the liquid crystal molecules when no voltage is applied to the liquid crystal in the IPS liquid crystal cell (that is, the first polarizing plate (polarizer)). The absorption axis direction is parallel to the long side of the screen of the IPS liquid crystal display device, and the absorption axis of the first polarizing plate (polarizer) is orthogonal to the absorption axis of the second polarizing plate (polarizer). Bonded to do.

  At this time, the polarizing plate arranged on the viewing side of the IPS liquid crystal cell 2 becomes the first polarizing plate, and the polarizing plate arranged on the backlight side becomes the second polarizing plate. Here, the film F2 is the isotropic film C, and the film F3 is the retardation film 107.

  Further, a laminate including a cover glass, a touch panel, a first polarizing plate, an IPS liquid crystal cell, and a second polarizing plate is provided on the backlight of the portable device, and the polarizing plate protection of the polarizing plate 207 in the laminated body is performed. A liquid crystal display device 330 of Example 20 was produced in the same manner as in Example 7 except that the film (polarizing plate protective film F4) was disposed so as to face the backlight.

[Examples 21 and 22]
IPS type liquid crystal display devices 331 and 332 were produced in the same manner as in Example 20 except that the type of polarizing plate having a retardation film was changed as shown in Table 2 below.

[Evaluation of IPS mode liquid crystal display]
(Viewing angle performance)
Using the liquid crystal display devices of Examples 1 to 22 and Comparative Examples 1 to 10, in a state where images are displayed in a bright room, visually, within a range of azimuth angles of 0 to 90 ° from the normal direction of the screen. The viewing angle was confirmed by observation. Here, observation results at 45 °, 60 °, and 75 ° were used for evaluation.

When the evaluation rank is Δ, it is determined that the characteristic is practical, when it is ◯, the characteristic is more practical, and when it is ◎, it is determined that there is no problem at all.
A: No light leakage ○: Little light leakage Δ: Some light leakage is observed.
×: Light leakage is observed.

(Display unevenness after forced test)
The liquid crystal display devices of Examples 1 to 22 and Comparative Examples 1 to 10 were left in a chamber at 80 ° C. and 90% RH for 100 hours. Next, the liquid crystal display device is taken out from the chamber, and the difference between the luminance near the four apexes of the display screen and the luminance near the center of the display screen in a state where the liquid crystal display device displays black in an atmosphere of 23 ° C. and 55% RH. (Image unevenness between the central portion and the peripheral portion) was visually observed, and image unevenness resistance (egg unevenness resistance) was evaluated according to the following criteria.

A: No occurrence of image unevenness (egg unevenness) is observed at all. ○: When observed very carefully, a slight image unevenness (egg unevenness) is recognized. The occurrence of egg unevenness is recognized, but the quality is acceptable for practical use. ×: The occurrence of obvious image unevenness (egg unevenness) is observed at three or more of the four vertices. Table 3 shows the above evaluation results.

  In addition, in the liquid crystal display devices according to Examples 1 to 22 and Comparative Examples 1 to 10 described in Table 2 above, the film F2 and the film F3 that are not the retardation films 101 to 126 are isotropic. Film C.

Here, as described above, in the isotropic film C, the in-plane retardation R0 is 1 nm, the thickness direction retardation Rth is 1 nm, the shrinkage is 0.1%, and the film thickness is converted to 40 μm. The moisture permeability was 200 (g / m ² / 24h).

  In addition, the liquid crystal display device 326 according to Comparative Example 7 has poor handling properties, and glass breakage occurs, so a liquid crystal display device cannot be manufactured, and viewing angle performance and display unevenness after a forced test cannot be measured. .

  From the above results, it was confirmed that the liquid crystal display devices according to Examples 1 to 19 achieved a reduction in thickness and weight, and had excellent durability against temperature and humidity changes while having a wide viewing angle. On the other hand, it was confirmed that the liquid crystal display devices according to Comparative Examples 1 to 6 and 8 to 10 are inferior in durability because the viewing angle performance is insufficient or display unevenness occurs after the forced test.

  In addition, from the comparison of the liquid crystal display devices according to Examples 7, 13, and 17 and the liquid crystal display devices according to Examples 20, 21, and 22, the liquid crystal display device according to the example has the retardation film at the position of the film F2. The isotropic film is disposed at the position of the film F3, and the isotropic film is disposed at the position of the film 2, and the retardation film is disposed at the position of the film F3. It was confirmed that each of these has excellent durability against changes in temperature and humidity while having a wide viewing angle.

DESCRIPTION OF SYMBOLS 1 Horizontal electric field mode type liquid crystal display device 2 Cover glass 3 1st polarizing plate 3a Polarizing plate protective film F1
3b First polarizer 3c film F2
4 Horizontal electric field mode type liquid crystal cell 5 Second polarizing plate 5a Polarizing plate protective film F4
5b Second polarizer 5c Film F3
6 Backlight 7 Liquid crystal element pixel region 8 Pixel electrode 9 Display electrode 10 Rubbing directions 11a and 11b of alignment film Liquid crystal molecules 12a and 12b aligned in the absence of voltage application Liquid crystal molecules aligned in the voltage application condition

Claims (6)

From the display surface side, in the horizontal electric field mode type liquid crystal display device having the cover glass, the first polarizing plate, the horizontal electric field mode type liquid crystal cell, the second polarizing plate and the backlight in this order,
The first polarizing plate has a polarizing plate protective film F1, a first polarizer and a film F2 in this order from the display surface side.
The second polarizing plate has a polarizing plate protective film F4, a second polarizer and a film F3 in this order from the backlight side.
The cover glass has a thickness of 0.1 to 0.3 mm,
The film thickness of said 1st polarizer and said 2nd polarizer is 1-15 micrometers,
The polarizing plate protective film F1 and the polarizing plate protective film F4 have a shrinkage ratio measured by the following method A of 0.01 to 0.50%,
At least one of the film F2 and the film F3 is a retardation film that satisfies the following conditions (1) to (3):
The film F2 and the film F3 that is not the retardation film are isotropic films that satisfy the following conditions (4) and (5):
(1) A cellulose acylate film containing as a main component a cellulose acylate having an aromatic acyl group;
(2) In an environment of 23 ° C. and 55% RH, the in-plane retardation R0 represented by the following formula (I) is 100 to 270 nm with respect to light having a wavelength of 590 nm, and is represented by the following formula (II). Thickness direction retardation Rth is -30 to 30 nm;
(3) The shrinkage percentage measured by the following method B is 0.10 to 1.00%;
(4) In an environment of 23 ° C. and 55% RH, the in-plane retardation R0 represented by the following formula (I) is 0 to 5 nm with respect to light having a wavelength of 590 nm, and is represented by the following formula (II). The thickness direction retardation Rth is -10 to 10 nm;
(5) The shrinkage percentage measured by the following method A is 0.01 to 1.00%;
Formula (I) R0 = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(However, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the film, ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film, nz represents the refractive index in the thickness direction z of the film, and d (nm) represents the thickness of the film).
[Method A]
The film viewed from the position in the polarizing plate in a 90% relative humidity 90% environment for about 100 hours, parallel to the absorption axis direction of the polarizer, the direction orthogonal to the absorption axis direction of the polarizer, the absorption axis of the polarizer Measure the shrinkage in 4 directions, 45 ° from the direction and 135 ° from the absorption axis direction of the polarizer, and set the largest value as the shrinkage.
[Method B]
Measure the shrinkage rate in the two directions of the slow axis direction and the direction perpendicular to the slow axis direction of the retardation film before and after 100 hours of aging at 80 ° C. and 90% relative humidity. The larger value is the shrinkage rate. To do.   The transverse electric field mode type liquid crystal display device according to claim 1, wherein one of the film F2 and the film F3 is the retardation film and the other is the isotropic film.   The transverse electric field mode type liquid crystal display device according to claim 1, wherein the retardation film has a thickness of 100 to 200 μm. The cellulose acylate having an aromatic acyl group has an aromatic acyl group substitution degree DSA of the following formula (III) and a total substitution degree DS of the following formula (IV). 2. A lateral electric field mode type liquid crystal display device according to 1.
Formula (III) 0.5 ≦ DSA ≦ 2.0
Formula (IV) 1.0 ≦ DS ≦ 3.0   The transverse electric field mode type liquid crystal display device according to any one of claims 1 to 4, wherein the retardation film is uniaxially stretched in a transport direction at a stretch ratio of 1.10 to 1.40.   The horizontal electric field according to claim 1, wherein the horizontal electric field mode type liquid crystal cell has a configuration in which a liquid crystal layer is provided between two glass substrates having a thickness of 0.2 to 0.7 mm. Mode type liquid crystal display device.