JPWO2007004399A1 - Transmission type liquid crystal display device - Google Patents

Abstract

The present invention provides a transmissive liquid crystal display device which has a high contrast ratio over a wide range and operates in an IPS mode and is capable of excellent image display from an oblique direction. The transmissive liquid crystal display device of the present invention comprises a retardation film (3) having an Nz3 value of 0 to 0.35 and an in-plane retardation of 60 to 450 nm on both sides of a liquid crystal cell driven in the IPS mode; Retardation films (4) each having an Nz4 value of 0.8 to 1.2 and an in-plane retardation of 60 to 450 nm are disposed, and at least one of the polarizing plates laminated on the retardation film on the liquid crystal cell side A transparent protective film (1-2) having an in-plane retardation of 0 to 5 nm and a thickness direction retardation of -20 to 20 nm is disposed on the surface.

Description

  The present invention relates to a transmissive liquid crystal display device having an optical film in which a polarizing plate and a retardation film are laminated and operating in a so-called IPS mode.

  Conventionally, as a liquid crystal display device, a so-called TN mode liquid crystal display device in which liquid crystal having positive dielectric anisotropy is twisted horizontally aligned between mutually opposing substrates has been mainly used. However, in the TN mode, due to its driving characteristics, birefringence is generated by liquid crystal molecules in the vicinity of the substrate even if black display is attempted, so that light leakage occurs and it is difficult to perform complete black display. On the other hand, in the IPS mode liquid crystal display device, the liquid crystal molecules have a homogeneous alignment substantially parallel to the substrate surface in the non-driven state, so that light passes through the liquid crystal layer with almost no change in its polarization plane. As a result, by disposing polarizing plates above and below the substrate, almost complete black display is possible in a non-driven state.

  However, in the IPS mode, although almost complete black display is possible in the normal direction of the panel, when the panel is observed from a direction deviated from the normal direction, the liquid crystal cell is generally observed from an oblique direction. In the direction deviated from the optical axis direction of the polarizing plate arranged above and below, there is a problem that the viewing angle becomes narrow as a result of light leakage that is unavoidable due to the characteristics of the polarizing plate. That is, in a polarizing plate using a commonly used triacetyl cellulose (TAC) film as a protective film, sufficient optical compensation can be performed with the retardation plate alone due to the birefringence in the thickness direction of the TAC film. There is a problem that the viewing angle becomes narrow.

In order to solve this problem, a polarizing plate is used in which a geometrical axis shift of the polarizing plate that occurs when observed from an oblique direction is compensated by a special retardation film (see, for example, Patent Document 1). . In the polarizing plate described in Patent Document 1, a retardation film having a specific retardation is laminated on a polarizing plate using a triacetyl cellulose (TAC) film as a protective film. However, with this configuration, it is difficult to realize a sufficiently wide viewing angle of the IPS mode liquid crystal display device. In addition, since the wavelength dispersion of the phase difference is large, there is a drawback that a color shift, which is a color difference when changing the place where the image is viewed in the front and oblique directions, is large.
JP 2004-157523 A

  The present invention is an IPS mode having an optical film (1) in which a polarizing plate (1) and a retardation film (3) are laminated, and an optical film (2) in which a polarizing plate (2) and a retardation film (4) are laminated. In the transmissive liquid crystal display device that operates in the above-described manner, at least one of the polarizing plate (1) and the polarizing plate (2) includes a transparent protective film (A) having no retardation in the thickness direction and in the plane, so that it is high over a wide range. An object of the present invention is to provide a transmissive liquid crystal display device having a contrast ratio and capable of displaying an excellent image even in an oblique direction.

The above object of the present invention is achieved by the following configurations.
1. A polarizing plate (1) and a polarizing plate (2) each having a transparent protective film laminated on both sides of a polarizer are arranged on both sides of a liquid crystal cell driven in an IPS mode composed of a pair of substrates sandwiching a liquid crystal layer. The following retardation film (3) is disposed between the liquid crystal cell and the polarizing plate (1), and the following retardation film (4) is disposed between the liquid crystal cell and the polarizing plate (2). In a transmissive liquid crystal display device,
The transparent protective film (1-2) on the liquid crystal cell side of the polarizing plate (1) and the transparent protective film (2-1) on the liquid crystal cell side of the polarizing plate (2) are the following (A). A transmissive liquid crystal display device comprising:
(A): The direction in which the in-plane refractive index is maximum is the X-axis, the direction perpendicular to the X-axis is the Y-axis, the thickness direction of the film is the Z-axis, and the refractive index in each axial direction is nx, ny, nz When the film thickness is d (nm), the in-plane retardation Re = (nx−ny) × d is 0 to 5 nm, and the thickness direction retardation Rth = {(nx + ny) / 2−nz. } × d is −20 to 20 nm. Retardation film (3): The direction in which the in-plane refractive index is the maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis. _{nx 3, ny 3, nz 3} , the thickness of the film when d ₃ and (nm), nz ₃ value represented by _{nz 3 = (nx 3 -nz 3} ) / (nx 3 -ny 3) is 0 to 0.35 is satisfied, and the in-plane retardation Re ₃ = (nx ₃ −ny ₃ ) × d ₃ is 60 to 450 nm.
Retardation film (4): The direction in which the in-plane refractive index is the maximum is the X-axis, the direction perpendicular to the X-axis is the Y-axis, and the thickness direction of the film is the Z-axis. _{nx 4, ny 4, nz 4} , the thickness of the film when d ₄ and (nm), nz ₄ value represented by _{nz 4 = (nx 4 -nz 4} ) / (nx 4 -ny 4) is 0.8 to 1.2 is satisfied, and the in-plane retardation Re ₄ = (nx ₄ −ny ₄ ) × d ₄ is 60 to 450 nm.
2. A polarizing plate (1) and a polarizing plate (2) each having a transparent protective film laminated on both sides of a polarizer are arranged on both sides of a liquid crystal cell driven in an IPS mode composed of a pair of substrates sandwiching a liquid crystal layer. The retardation film (3) is disposed between the liquid crystal cell and the polarizing plate (1), and the retardation film (4) is disposed between the liquid crystal cell and the polarizing plate (2). In the transmissive liquid crystal display device
2. The transmissive liquid crystal display device as described in 1 above, wherein the transparent protective film (2-1) on the liquid crystal cell side of the polarizing plate (2) is the above (A).
3. A polarizing plate (1) and a polarizing plate (2) each having a transparent protective film laminated on both sides of a polarizer are arranged on both sides of a liquid crystal cell driven in an IPS mode composed of a pair of substrates sandwiching a liquid crystal layer. The retardation film (3) is disposed between the liquid crystal cell and the polarizing plate (1), and the retardation film (4) is disposed between the liquid crystal cell and the polarizing plate (2). In the transmissive liquid crystal display device
The transparent protective film (1-2) on the liquid crystal cell side of the polarizing plate (1) and the transparent protective film (2-1) on the liquid crystal cell side of the polarizing plate (2) are both (A). 2. The transmissive liquid crystal display device as described in 1 above.
4). 4. The transmissive liquid crystal display device according to any one of 1 to 3, wherein the transparent protective film (A) is a cellulose ester film.
5. 5. The transmission type liquid crystal display device as described in 4 above, wherein the cellulose ester film (A) has a thickness of 30 to 60 μm.
6). 4. The cellulose ester film according to (4) or (5) above, wherein the cellulose ester film (A) contains a polymer obtained by polymerizing a compound having an ethylenic double bond having a weight average molecular weight of 500 to 30,000. Transmission type liquid crystal display device.
7). The transmissive liquid crystal display device according to any one of 1 to 6, wherein the polarizer uses ethylene-modified polyvinyl alcohol.
8). 8. The transmissive liquid crystal display device according to any one of 1 to 7, wherein the liquid crystal cell driven in the IPS mode has a phase difference value at 550 nm of 230 to 360 nm when no voltage is applied. .

9. An optical film in which the polarizing plate (1) and the retardation film (3) are laminated so that the absorption axis of the polarizing plate (1) and the slow axis of the retardation film (3) are orthogonal or parallel to each other. The polarizing plate (2) and the retardation film (4) were laminated so that the absorption axis of the polarizing plate (2) and the slow axis of the retardation film (4) were orthogonal or parallel to each other. An optical film (2) is used, and the optical film (1) and the optical film (2) are combined with the liquid crystal so that the absorption axes of the polarizing plate (1) and the polarizing plate (2) are orthogonal to each other. 9. The transmissive liquid crystal display device according to any one of 1 to 8, wherein the transmissive liquid crystal display device is disposed on each side of the cell.
10. The optical film (1) is disposed on the cell substrate on the viewing side, and the optical film (2) is disposed on the cell substrate on the incident side. The abnormal light of the liquid crystal substance in the liquid crystal cell when no voltage is applied. 10. The transmission type liquid crystal display device as described in 9 above, wherein the refractive index direction and the absorption axis of the polarizing plate on the incident side are in a parallel state.
11. The optical film (1) is laminated so that the absorption axis of the polarizing plate (1) and the slow axis of the retardation film (3) are parallel, and the optical film (2) is a polarizing plate ( 10. The transmission type liquid crystal display device as described in 9 above, wherein the absorption axis of 2) and the retardation film (4) are laminated so that the slow axis is parallel.

  Transmission operating in IPS mode having optical film (1) laminated with polarizing plate (1) and retardation film (3) and optical film (2) laminated with polarizing plate (2) and retardation film (4) In the liquid crystal display device, the retardation of the polarizing plate (1) and the polarizing plate (2) causes a decrease in contrast of the liquid crystal display device. In particular, in the IPS mode, the contrast is greatly reduced when viewed from an oblique direction, which causes a so-called narrowing of the viewing angle. In the polarizing plate (1) and the polarizing plate (2), it is the transparent protective film on the liquid crystal cell side that affects the contrast and the viewing angle, and this transparent protective film has no in-plane retardation Re substantially. Even if a triacetyl cellulose film (TAC film) was used, the contrast and viewing angle were not satisfactory because of the retardation Rth in the thickness direction. By reducing the thickness of the triacetyl cellulose film (TAC film) in order to reduce the thickness direction retardation Rth, the contrast and viewing angle can be improved to some extent, but this is still sufficient because the Rth in the thickness direction remains. Contrast and viewing angle performance has not been achieved.

Therefore, by using the transparent protective film (A) having no retardation in the thickness direction and in the plane as the transparent protective film on the liquid crystal cell side of the polarizing plate (1) and the polarizing plate (2), the contrast and the viewing angle are greatly increased. Can be improved. In particular, the retardation film (3) having an Nz ₃ value of 0 to 0.35 and the transparent protective film on the liquid crystal cell side of the polarizing plate (2) on the opposite side across the liquid crystal cell are used for the thickness direction and in-plane retardation. By using the transparent protective film (A) that does not have a large improvement effect can be obtained. Furthermore, the polarizing plate (1) and the polarizing plate (2) have both the transparent protective film on the liquid crystal cell side as the transparent protective film (A) having no retardation in the thickness direction and in the plane, so that the polarizing plate has. Since the phase difference can be substantially eliminated, the viewing angle compensation effect of the phase difference film (3) and the phase difference film (4) is not impaired, so that the contrast and the viewing angle can be remarkably improved.

1 shows a configuration of an IPS mode liquid crystal display device of the present invention. It is a schematic diagram which shows the absorption axis direction of the polarizing plate of this invention, the slow axis direction of a phase difference plate, and the extraordinary light refraction direction of a liquid crystal cell.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  In the IPS mode, a polarizing plate is used in which a geometrical axis shift of the polarizing plate that occurs when observed from an oblique direction is compensated by a retardation film. A polarizing plate capable of obtaining such an effect is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-157523.

  In the polarizing plate described in JP-A No. 2004-157523, a retardation film having a specific retardation is laminated on a polarizing plate using a commonly used triacetyl cellulose (TAC) film as a protective film. Optical film is used. However, with this configuration, it is difficult to realize a sufficiently wide viewing angle of the IPS mode liquid crystal display device. Further, since the wavelength dispersion of the phase difference is large, there is a drawback that a color shift, which is a color difference when observed from the front and oblique directions, is large.

Therefore, we arrange the polarizing plate (1) and the polarizing plate (2), which are formed by laminating transparent protective films on both sides of the polarizer, on both sides of the liquid crystal cell, respectively, and the liquid crystal cell and the polarizing plate (1). The following retardation film (3) is placed between
The following retardation film (4) is disposed between the liquid crystal cell and the polarizing plate (2), the transparent protective film (1-2) on the liquid crystal cell side of the polarizing plate (1), and the polarizing plate (2). A transparent liquid crystal display device characterized in that at least one transparent protective film of the transparent protective film (2-1) on the liquid crystal cell side is the following (A). However, it was possible to obtain a transmissive liquid crystal display device that operates in the IPS mode with a small color shift, which is a color difference when changing the viewing place.
(A): The direction in which the in-plane refractive index is maximum is the X-axis, the direction perpendicular to the X-axis is the Y-axis, the thickness direction of the film is the Z-axis, and the refractive index in each axial direction is nx, ny, nz When the film thickness is d (nm), the in-plane retardation Re = (nx−ny) × d is 0 to 5 nm, and the thickness direction retardation Rth = {(nx + ny) / 2−nz. } × d is −20 to 20 nm. (3): The direction in which the in-plane refractive index is maximum is the X-axis, the direction perpendicular to the X-axis is the Y-axis, the thickness direction of the film is the Z-axis, and the refractive index at 550 nm in each axial direction is nx ₃ ny _3, nz _3, the thickness of the film when d ₃ and _{(nm), nz 3 = (} nx 3 -nz 3) / nz value represented by (nx ₃ -ny ₃₎ is 0-0. 35 and the in-plane retardation Re ₃ = (nx ₃ −ny ₃ ) × d ₃ is 60 to 450 nm.
(4): The direction in which the in-plane refractive index is maximum is the X-axis, the direction perpendicular to the X-axis is the Y-axis, the thickness direction of the film is the Z-axis, and the refractive index at 550 nm in each axial direction is nx ₄ ny _4, nz _4, the thickness of the film when the _{d 4 (nm), nz 4} = (nx 4 -nz 4) / nz value represented by (nx ₄ -ny ₄₎ is 0.8 1.2 is satisfied, and the in-plane retardation Re ₄ = (nx ₄ −ny ₄ ) × d ₄ is 60 to 450 nm.

  Here, the thickness direction retardation Rth of (A) is more preferably in the range of −10 to 10 nm.

  When the transparent protective film (1-2) on the liquid crystal cell side of the polarizing plate (1) and the transparent protective film (2-1) on the liquid crystal cell side of the polarizing plate (2) are not used, and The transparent protective film (1-1) opposite to the liquid crystal cell of the polarizing plate (1) and the transparent protective film (2-2) opposite to the liquid crystal cell of the polarizing plate (2) are not particularly limited and are usually commercially available. The same triacetyl cellulose film (TAC film) or (A) can be used.

  In particular, a weight average obtained by polymerizing a compound containing an ethylenic double bond as a specific technique for reducing the retardation in the thickness direction of a commonly used triacetyl cellulose film (TAC film) and (A). When a polymer having a molecular weight of 500 to 30,000 or less was used, a transparent protective film was found that can reduce the retardation value in the thickness direction and has excellent moisture permeability and retention.

  In the present invention, the polarizing plate (1) and the retardation film (3) are laminated so that the absorption axis of the polarizing plate (1) and the slow axis of the retardation film (3) are orthogonal or parallel to each other. An optical film (1) is used, and the polarizing plate (2) and the retardation film (4) so that the absorption axis of the polarizing plate (2) and the slow axis of the retardation film (4) are orthogonal or parallel to each other. ) Is an optical film (2).

  In the optical film according to the present invention, when the polarizing plate having the protective film having the predetermined retardation value is arranged in a crossed Nicol state, light leakage in a direction shifted from the optical axis is caused by the specific retardation film. It can be eliminated, and is preferably used for an IPS mode liquid crystal display device. In particular, it has a function of compensating for a decrease in contrast in an oblique direction of the liquid crystal layer.

The retardation film (3) has an Nz ₃ value of 0 to 0.35 and an in-plane retardation Re ₃ of 60 to 450 nm. The Nz value is preferably 0.1 or more, more preferably 0.15 or more from the viewpoint of enhancing the compensation function. On the other hand, the Nz ₃ value is preferably 0.34 or less, more preferably 0.3 or less. The in-plane retardation Re ₃ is preferably 123 nm or more, and more preferably 128 nm or more from the viewpoint of enhancing the compensation function.

The retardation film (4) has an Nz ₄ value of 0.8 to 1.2 and an in-plane retardation Re ₄ of 60 to 450 nm. The Nz ₄ value is preferably 0.9 to 1.1 from the viewpoint of enhancing the compensation function. The in-plane retardation Re ₄ is preferably 123 nm or more, and more preferably 128 nm or more from the viewpoint of enhancing the compensation function.

  The optical film is preferably applied to an IPS mode liquid crystal display device using an IPS mode liquid crystal cell having a retardation value at 550 nm of 230 to 360 nm when no voltage is applied.

  The optical film according to the present invention is preferably applied to an IPS mode liquid crystal display device. However, the IPS mode liquid crystal display device in the present invention means a horizontal electric field type liquid crystal display device, which is a fringe electric field switching (FFS). : Fringe-Field Switching) mode is also included in the present invention.

  The material constituting the IPS mode liquid crystal cell is not particularly limited, and normally used materials can be used as appropriate, but the liquid crystal cell has a phase difference value at 550 nm of 230 to 360 nm when no voltage is applied. Is preferable from the viewpoint that a compensation function by a retardation film can be suitably imparted. The phase difference value at 550 nm of the liquid crystal cell is more preferably 230 to 360 nm, and further preferably 250 to 280 nm when no voltage is applied.

  The present invention also relates to a transmissive liquid crystal display device having a liquid crystal cell driven in an IPS mode composed of a pair of substrates sandwiching a liquid crystal layer, and a pair of polarizing plates arranged in an orthogonal state on both sides of the liquid crystal cell. The transmissive liquid crystal display device is characterized in that, as at least one polarizing plate, the optical film is disposed such that the retardation film side is the liquid crystal cell side.

  Further, in the transmissive liquid crystal display device, when the optical film is arranged on the cell substrate on the viewing side and the incident side (also referred to as the backlight side), the extraordinary refractive index direction of the liquid crystal substance in the liquid crystal cell in the non-application state And the absorption axis of the polarizing plate of the optical film on the incident side are preferably in a parallel state.

  As described above, in the case where the optical film is disposed on the cell substrate on the viewing side and the incident side, the optical film is polarized because it reduces the influence of wavelength dispersion of the retardation film for controlling the polarization. It is preferable to use a laminate in which the absorption axis of the plate and the slow axis of the retardation film are parallel to each other.

  In the IPS mode transmissive liquid crystal display device of the present invention, an optical film according to the present invention in which a polarizing plate and a retardation film are laminated is disposed on both sides of an IPS mode liquid crystal cell. Light leakage at the time of black display, which has conventionally occurred, can be reduced. Such an IPS mode transmissive liquid crystal display device has a high contrast ratio in all directions, and can realize a display that is easy to see at a wide viewing angle.

  Hereinafter, an optical film and an image display device according to the present invention will be described with reference to the drawings.

  The IPS mode liquid crystal display device of the present invention has the configuration shown in FIG.

  The transparent protective films (1-1) and (1-2) are polarizing plate protective films of the polarizing plate (1), and the transparent protective films (2-1) and (2-2) are polarizing plates of the polarizing plate (2). It is a plate protective film, and is disposed on each surface across an IPS mode liquid crystal cell. Here, the retardation film (3) is disposed between the transparent protective film (1-2) and the IPS mode liquid crystal cell. Further, the retardation film (4) is disposed between the transparent protective film (2-1) and the IPS mode liquid crystal cell. In this case, the positions of the optical film (1) and the optical film (2) may be reversed.

  That is, even if the said optical film (1) is arrange | positioned at the visual recognition side, this optical film (1) may be arrange | positioned at the backlight side. Further, the transparent protective film disposed on the viewer side, that is, the transparent protective film (1-1) in FIG. 1, is preferably provided with a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer. .

  The transparent protective film (1-1) or the transparent protective film (2-2) provided on the polarizer has an in-plane retardation Re of 10 nm or less and a thickness direction retardation Rth of 30 to 100 nm. Can be used without any particular restrictions. Examples of the material for forming such a transparent protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene and acrylonitrile / Examples thereof include styrene polymers such as styrene copolymers (AS resins), polycarbonate polymers, and the like. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like can also be mentioned as examples of the polymer forming the transparent protective film. The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, and silicone. As a material for the transparent protective film, triacetyl cellulose which is generally used as a transparent protective film for a polarizer is suitable. These transparent protective films can be appropriately stretched so as to have the in-plane retardation Re and the thickness direction retardation Rth.

  Moreover, when the transparent protective film used for this invention is arrange | positioned at the visual recognition side, it is preferable to provide the following functional layer in at least one surface.

(Hard coat layer)
The transparent protective film (also referred to as a polarizing plate protective film) used in the present invention is preferably provided with a hard coat layer as a functional layer.

  The hard coat layer used in the present invention is provided on at least one surface of the polarizing plate protective film. The polarizing plate protective film of the present invention preferably comprises an antireflection film in which an antireflection layer (high refractive index layer, low refractive index layer, etc.) is provided on the hard coat layer.

  As the hard coat layer, an actinic radiation curable resin layer is preferably used.

  The actinic radiation curable resin layer refers to a layer mainly composed of a resin that cures through a crosslinking reaction or the like by irradiation with actinic rays such as ultraviolet rays or electron beams. As the actinic radiation curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and a hard coat layer is formed by curing by irradiation with actinic radiation such as ultraviolet rays or electron beams. Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, and a resin curable by ultraviolet irradiation is preferable.

  As the ultraviolet curable resin, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, or an ultraviolet curable epoxy resin is preferable. Used.

  UV curable acrylic urethane resins generally include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter referred to as acrylates) in products obtained by reacting polyester polyols with isocyanate monomers or prepolymers. It can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate. For example, those described in JP-A-59-151110 can be used.

  For example, a mixture of 100 parts Unidic 17-806 (Dainippon Ink Co., Ltd.) and 1 part Coronate L (Nihon Polyurethane Co., Ltd.) is preferably used.

  Examples of UV curable polyester acrylate resins include those which are easily formed when 2-hydroxyethyl acrylate and 2-hydroxy acrylate monomers are generally reacted with polyester polyols. JP-A-59-151112 Can be used.

  Specific examples of the ultraviolet curable epoxy acrylate resin include an epoxy acrylate as an oligomer, a reactive diluent and a photoreaction initiator added to the oligomer, and a reaction. Those described in US Pat. No. 105738 can be used.

  Specific examples of UV curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate, etc. Can be mentioned.

  Specific examples of the photoreaction initiator of these ultraviolet curable resins include benzoin and derivatives thereof, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and the like. You may use with a photosensitizer. The photoinitiator can also be used as a photosensitizer. In addition, when using an epoxy acrylate photoinitiator, a sensitizer such as n-butylamine, triethylamine, or tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer used in the ultraviolet curable resin composition is 0.1 to 15 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the composition.

  Examples of the resin monomer may include general monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, benzyl acrylate, cyclohexyl acrylate, vinyl acetate, and styrene as monomers having one unsaturated double bond. In addition, monomers having two or more unsaturated double bonds include ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyldimethyl adiacrylate, and the above trimethylolpropane. Examples thereof include triacrylate and pentaerythritol tetraacryl ester.

  Examples of commercially available ultraviolet curable resins that can be used in the present invention include ADEKA OPTMER KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (Asahi Denka ( Co., Ltd.); Koeihard A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS -101, FT-102Q8, MAG-1-P20, AG-106, M-101-C (manufactured by Guangei Chemical Co., Ltd.); Seika Beam PHC2210 (S), PHC X-9 (K-3), PHC2213, DP -10, DP-20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (manufactured by Dainichi Seika Kogyo Co., Ltd.) KRM7033, KRM7039, KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (manufactured by Daicel UCB); RC-5015, RC-5016, RC-5020, RC-5031, RC-5100, RC-5102, RC-5120 RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (manufactured by Dainippon Ink & Chemicals, Inc.); 340 clear (manufactured by China Paint Co., Ltd.); Sunrad H-601, RC-750, RC-700, RC-600, RC-500, RC-611, RC-612 (manufactured by Sanyo Chemical Industries); SP -1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.); RCC-15C (manufactured by Grace Japan Co., Ltd.), Aronix M-6100, M-8030, M-8060 (manufactured by Toagosei Co., Ltd.), etc. Can be selected as appropriate.

  Examples of specific compounds include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate, and the like. .

  These actinic ray curable resin layers can be coated by a known method such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die coater, or an ink jet method.

As a light source for curing an ultraviolet curable resin by a photocuring reaction to form a cured film layer, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. These light sources are preferably air-cooled or water-cooled. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is preferably 5 to 150 mJ / cm ² , particularly preferably 20 to 100 mJ / cm ² .

  Moreover, it is preferable to reduce oxygen concentration to 0.01 to 2% by nitrogen purge in the irradiation part.

  Moreover, when irradiating actinic radiation, it is preferable to carry out while applying tension | tensile_strength in the conveyance direction of a film, More preferably, it is performing applying tension | tensile_strength also in the width direction. The tension to be applied is preferably 30 to 300 N / m. The method for applying the tension is not particularly limited, and the tension may be applied in the conveying direction on the back roll, or the tension may be applied in the width direction or the biaxial direction by a tenter. This makes it possible to obtain a film having further excellent flatness.

  Examples of the organic solvent for the UV curable resin layer composition coating solution include hydrocarbons (toluene, xylene), alcohols (methanol, ethanol, isopropanol, butanol, cyclohexanol), ketones (acetone, methyl ethyl ketone, methyl isobutyl). Ketone), esters (methyl acetate, ethyl acetate, methyl lactate), glycol ethers, and other organic solvents, or a mixture thereof can be used. Propylene glycol monoalkyl ether (1 to 4 carbon atoms of the alkyl group) or propylene glycol monoalkyl ether acetate ester (1 to 4 carbon atoms of the alkyl group) is 5% by mass or more, more preferably 5 to 80%. It is preferable to use the organic solvent containing at least mass%.

  In addition, it is particularly preferable to add a silicon compound to the ultraviolet curable resin layer composition coating solution. For example, polyether-modified silicone oil is preferably added. The number average molecular weight of the polyether-modified silicone oil is, for example, 1000 to 100000, preferably 2000 to 50000. If the number average molecular weight is less than 1000, the drying property of the coating film decreases, and conversely, the number average When the molecular weight exceeds 100,000, it tends to be difficult to bleed out to the coating surface.

  Commercially available silicon compounds include DKQ8-779 (trade name, manufactured by Dow Corning), SF3771, SF8410, SF8411, SF8419, SF8421, SF8428, SH200, SH510, SH1107, SH3749, SH3771, BX16-034, SH3746, SH3749, SH8400, SH3771M, SH3772M, SH3773M, SH3775M, BY-16-837, BY-16-839, BY-16-869, BY-16-870, BY-16-004, BY-16-891, BY-16 872, BY-16-874, BY22-008M, BY22-012M, FS-1265 (above, product names manufactured by Toray Dow Corning Silicone), KF-101, KF-100T, KF351, KF3 2, KF353, KF354, KF355, KF615, KF618, KF945, KF6004, Silicone X-22-945, X22-160AS (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), XF3940, XF3949 (trade name, manufactured by Toshiba Silicone Co., Ltd.) ), Disparon LS-009 (manufactured by Enomoto Kasei Co., Ltd.), Granol 410 (manufactured by Kyoeisha Oil Chemical Co., Ltd.), TSF4440, TSF4441, TSF4445, TSF4446, TSF4452, TSF4460 (manufactured by GE Toshiba Silicone), BYK-306, BYK- 330, BYK-307, BYK-341, BYK-344, BYK-361 (manufactured by BYK-Japan) L series (for example, L7001, L-7006, L-7604, L-9000) manufactured by Nippon Unicar Co., Ltd. Y Over's, FZ series (FZ-2203, FZ-2206, FZ-2207) and the like, it is preferably used.

  These components enhance the applicability to the substrate and the lower layer. When added to the outermost surface layer of the laminate, it not only improves the water repellency, oil repellency and antifouling properties of the coating film, but also exhibits an effect on the scratch resistance of the surface. These components are preferably added in a range of 0.01 to 3% by mass with respect to the solid component in the coating solution.

  As a method for applying the ultraviolet curable resin composition coating solution, the above-described methods can be used. The coating amount is suitably 0.1 to 30 μm, preferably 0.5 to 15 μm, as the wet film thickness. The dry film thickness is 0.1 to 20 μm, preferably 1 to 10 μm.

The ultraviolet curable resin composition is preferably irradiated with ultraviolet rays during or after coating and drying. The irradiation time for obtaining the irradiation dose of the active ray of 5 to 150 mJ / cm ² is from 0.1 second to 5 seconds. Minutes are good, and 0.1 to 10 seconds is more preferable from the viewpoint of curing efficiency or work efficiency of the ultraviolet curable resin.

Moreover, it is preferable that the illuminance of these active ray irradiation parts is 50-150 mW / cm < ² >.

  In order to prevent blocking, improve scratch resistance, etc., or to provide antiglare property or light diffusibility, or to adjust the refractive index, the cured resin layer thus obtained is fine particles of an inorganic compound or an organic compound. Can also be added.

  It is preferable to add fine particles to the hard coat layer used in the present invention, and as the inorganic fine particles used, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, calcium carbonate, calcium carbonate, talc, clay, Mention may be made of calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. In particular, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and the like are preferably used.

  The organic fine particles include polymethacrylic acid methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder. Polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, or polyfluoroethylene resin powder can be added to the ultraviolet curable resin composition. Particularly preferred are cross-linked polystyrene particles (for example, SX-130H, SX-200H, SX-350H, manufactured by Soken Chemical) and polymethyl methacrylate-based particles (for example, MX150, MX300, manufactured by Soken Chemical).

  The average particle diameter of these fine particle powders is preferably 0.005 to 5 μm, and particularly preferably 0.01 to 1 μm. As for the ratio of a ultraviolet curable resin composition and fine particle powder, it is desirable to mix | blend so that it may be 0.1-30 mass parts with respect to 100 mass parts of resin compositions.

  The ultraviolet curable resin layer is a clear hard coat layer having a center line average roughness (Ra) defined by JIS B 0601 of 1 to 50 nm or an antiglare layer having an Ra of about 0.1 to 1 μm. Is preferred. The center line average roughness (Ra) is preferably measured with an optical interference type surface roughness measuring instrument, and can be measured using, for example, RST / PLUS manufactured by WYKO.

The hard coat layer used in the present invention preferably contains an antistatic agent. Examples of the antistatic agent include Sn, Ti, In, Al, Zn, Si, Mg, Ba, Mo, W and A conductive material containing at least one element selected from the group consisting of V as a main component and having a volume resistivity of 10 ⁷ Ω · cm or less is preferable.

  Examples of the antistatic agent include metal oxides and composite oxides having the above elements.

Examples of metal oxides include, for example, ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₂ , V ₂ O ₅ , or complex oxides thereof. ZnO, In ₂ O ₃ , TiO ₂ and SnO ₂ are particularly preferable. Examples of containing different atoms include, for example, addition of Al and In to ZnO, addition of Nb and Ta to TiO ₂ , and addition of Sb, Nb and halogen elements to SnO ₂ . Addition is effective. The amount of these different atoms added is preferably in the range of 0.01 to 25 mol%, particularly preferably in the range of 0.1 to 15 mol%. In addition, the volume resistivity of these metal oxide powders having conductivity is 10 ⁷ Ω · cm or less, particularly 10 ⁵ Ω · cm or less.

(Antireflection layer)
The polarizing plate protective film used in the present invention is preferably provided with an antireflection layer as a functional layer on the hard coat layer. In particular, a low refractive index layer containing hollow fine particles is preferable.

(Low refractive index layer)
The low refractive index layer used in the present invention preferably contains hollow fine particles, and more preferably contains a silicon alkoxide, a silane coupling agent, a curing agent and the like.

<Hollow particles>
The low refractive index layer preferably contains the following hollow fine particles.

  The hollow fine particles referred to here are (1) composite particles composed of porous particles and a coating layer provided on the surface of the porous particles, or (2) hollow inside, and the contents are a solvent, gas or Cavity particles filled with a porous material. In addition, the coating liquid for low refractive index layers should just contain either (1) composite particle | grains or (2) cavity particle | grains, and may contain both.

  The hollow particles are particles having cavities inside, and the cavities are surrounded by particle walls. The cavity is filled with contents such as a solvent, a gas, or a porous material used at the time of preparation. It is desirable that the average particle size of such inorganic fine particles is in the range of 5 to 300 nm, preferably 10 to 200 nm. The inorganic fine particles used are appropriately selected according to the thickness of the transparent film to be formed, and may be in the range of 2/3 to 1/10 of the film thickness of the formed transparent film such as a low refractive index layer. desirable. These inorganic fine particles are preferably used in a state of being dispersed in an appropriate medium in order to form a low refractive index layer. As the dispersion medium, water, alcohol (for example, methanol, ethanol, isopropyl alcohol), ketone (for example, methyl ethyl ketone, methyl isobutyl ketone), and ketone alcohol (for example, diacetone alcohol) are preferable.

  The thickness of the coating layer of the composite particles or the thickness of the particle walls of the hollow particles is desirably in the range of 1 to 20 nm, preferably 2 to 15 nm. In the case of composite particles, when the thickness of the coating layer is less than 1 nm, the particles may not be completely covered, and the low refractive index effect may not be sufficiently obtained. On the other hand, when the thickness of the coating layer exceeds 20 nm, the porosity (pore volume) of the composite particles may be lowered, and the low refractive index effect may not be sufficiently obtained. In the case of hollow particles, if the particle wall thickness is less than 1 nm, the particle shape may not be maintained, and even if the thickness exceeds 20 nm, the effect of low refractive index may not be sufficiently exhibited. .

The coating layer of the composite particles or the particle wall of the hollow particles is preferably composed mainly of silica. The coating layer of the composite particle or the particle wall of the hollow particle may contain a component other than silica, specifically, Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO _2. CeO ₂ , P ₂ O ₃ , Sb ₂ O ₃ , MoO ₃ , ZnO ₂ , WO _{3 and the} like. Examples of the porous particles constituting the composite particles include those made of silica, those made of silica and an inorganic compound other than silica, and those made of CaF ₂ , NaF, NaAlF ₆ , MgF, and the like. Among these, porous particles made of a composite oxide of silica and an inorganic compound other than silica are particularly preferable. Examples of inorganic compounds other than silica include Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , P ₂ O ₃ , Sb ₂ O ₃ , MoO ₃ , ZnO ₂ , WO _{3 and the} like. 1 type or 2 types or more can be mentioned. In such porous particles, the molar ratio MOX / SiO ₂ when the silica is represented by SiO ₂ and the inorganic compound other than silica is represented by oxide (MOX) is 0.0001 to 1.0, preferably It is desirable to be in the range of 0.001 to 0.3. It is difficult to obtain a porous particle having a molar ratio MOX / SiO ₂ of less than 0.0001, and even if it is obtained, conductivity is not exhibited. On the other hand, if the molar ratio MOX / SiO _{2 of} the porous particles exceeds 1.0, the ratio of silica decreases, so that particles having a small pore volume and a low refractive index may not be obtained.

  The pore volume of such porous particles is desirably in the range of 0.1 to 1.5 ml / g, preferably 0.2 to 1.5 ml / g. If the pore volume is less than 0.1 ml / g, particles having a sufficiently reduced refractive index cannot be obtained. If the pore volume exceeds 1.5 ml / g, the strength of the fine particles is lowered, and the strength of the resulting coating may be lowered. is there.

  Incidentally, the pore volume of such porous particles can be determined by a mercury intrusion method. Examples of the contents of the hollow particles include a solvent, a gas, and a porous substance used at the time of preparing the particles. The solvent may contain an unreacted particle precursor used when preparing the hollow particles, the catalyst used, and the like. Moreover, what consists of the compound illustrated by the said porous particle as a porous substance is mentioned. These contents may be composed of a single component or may be a mixture of a plurality of components.

  As a method for producing such inorganic fine particles, for example, the method for preparing composite oxide colloidal particles disclosed in paragraphs [0010] to [0033] of JP-A-7-133105 is suitably employed. Specifically, when the composite particles are composed of silica and an inorganic compound other than silica, the inorganic compound particles are produced from the following first to third steps.

First Step: Preparation of Porous Particle Precursor In the first step, an alkali aqueous solution of a silica raw material and an inorganic compound raw material other than silica is separately prepared in advance, or a silica raw material and an inorganic compound raw material other than silica are prepared in advance. A mixed aqueous solution is prepared, and this aqueous solution is gradually added to an aqueous alkaline solution having a pH of 10 or more while stirring according to the composite ratio of the target composite oxide to prepare a porous particle precursor.

  As the silica raw material, alkali metal, ammonium or organic base silicate is used. Sodium silicate (water glass) or potassium silicate is used as the alkali metal silicate. Examples of the organic base include quaternary ammonium salts such as tetraethylammonium salt, and amines such as monoethanolamine, diethanolamine, and triethanolamine. The ammonium silicate or the organic base silicate includes an alkaline solution obtained by adding ammonia, a quaternary ammonium hydroxide, an amine compound or the like to a silicic acid solution.

  Moreover, the alkali-soluble conductive compound is used as a raw material for inorganic compounds other than silica.

Although the pH value of the mixed aqueous solution changes simultaneously with the addition of these aqueous solutions, an operation for controlling the pH value within a predetermined range is not particularly required. The aqueous solution finally has a pH value determined by the type of inorganic oxide and the mixing ratio thereof. There is no restriction | limiting in particular in the addition rate of the aqueous solution at this time. Further, in the production of composite oxide particles, a dispersion of seed particles can be used as a starting material. The seed particles are not particularly limited, but inorganic oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ or ZrO ₂ or fine particles of these composite oxides are used. Usually, these sols are used. Can do. Furthermore, the porous particle precursor dispersion obtained by the above production method may be used as a seed particle dispersion. When the seed particle dispersion is used, the pH of the seed particle dispersion is adjusted to 10 or more, and then the aqueous solution of the compound is added to the above-described alkaline aqueous solution while stirring. Also in this case, it is not always necessary to control the pH of the dispersion. In this way, when seed particles are used, it is easy to control the particle size of the porous particles to be prepared, and particles with uniform particle sizes can be obtained.

  The silica raw material and the inorganic compound raw material described above have high solubility on the alkali side. However, when both are mixed in this highly soluble pH region, the solubility of oxo acid ions such as silicate ions and aluminate ions decreases, and these composites precipitate and grow into fine particles, or seed particles. Particle deposition occurs on the top. Therefore, it is not always necessary to perform pH control as in the conventional method for precipitation and growth of fine particles.

The composite ratio of silica and inorganic compound other than silica in the first step is that the inorganic compound relative to silica is converted to oxide (MOx), and the molar ratio of MOx / SiO ₂ is 0.05 to 2.0, preferably It is desirable to be within the range of 0.2 to 2.0. Within this range, the pore volume of the porous particles increases as the proportion of silica decreases. However, even when the molar ratio exceeds 2.0, the pore volume of the porous particles hardly increases. On the other hand, when the molar ratio is less than 0.05, the pore volume becomes small. When preparing hollow particles, the molar ratio of MOx / SiO ₂ is preferably in the range of 0.25 to 2.0.

Second step: Removal of inorganic compound other than silica from porous particles In the second step, inorganic compounds other than silica (elements other than silicon and oxygen) are obtained from the porous particle precursor obtained in the first step. At least a portion is selectively removed. As a specific removal method, the inorganic compound in the porous particle precursor is dissolved and removed using a mineral acid or an organic acid, or is contacted with a cation exchange resin for ion exchange removal.

  The porous particle precursor obtained in the first step is a particle having a network structure in which silicon and an inorganic compound constituent element are bonded via oxygen. By removing the inorganic compound (elements other than silicon and oxygen) from the porous particle precursor in this way, porous particles having a larger porosity and a larger pore volume can be obtained. Further, if the amount of removing the inorganic oxide (elements other than silicon and oxygen) from the porous particle precursor is increased, the hollow particles can be prepared.

  In addition, prior to removing inorganic compounds other than silica from the porous particle precursor, a silicic acid solution obtained by removing the alkali metal salt of silica from the porous particle precursor dispersion obtained in the first step. Alternatively, it is preferable to form a silica protective film by adding a hydrolyzable organosilicon compound. The thickness of the silica protective film may be 0.5 to 15 nm. Even if the silica protective film is formed, the protective film in this step is porous and thin, so that it is possible to remove inorganic compounds other than silica described above from the porous particle precursor.

  By forming such a silica protective film, inorganic compounds other than silica described above can be removed from the porous particle precursor while maintaining the particle shape. Further, when forming the silica coating layer described later, the pores of the porous particles are not blocked by the coating layer, and therefore the silica coating layer described later is formed without reducing the pore volume. Can do. Note that when the amount of the inorganic compound to be removed is small, the particles are not broken, and thus it is not always necessary to form a protective film.

  When preparing hollow particles, it is desirable to form this silica protective film. When preparing the hollow particles, the inorganic compound is removed to obtain a hollow particle precursor composed of a silica protective film, a solvent in the silica protective film, and an undissolved porous solid content. When a coating layer to be described later is formed on the precursor, the formed coating layer becomes a particle wall to form hollow particles.

The amount of the silica source added for forming the silica protective film is preferably small as long as the particle shape can be maintained. If the amount of the silica source is too large, the silica protective film becomes too thick, and it may be difficult to remove inorganic compounds other than silica from the porous particle precursor. The hydrolyzable organic silicon compound used for the silica protective film formed of the general formula _{R n Si (OR ') 4} - n [R, R': an alkyl group, an aryl group, a vinyl group, such as acrylic group An alkoxysilane represented by a hydrocarbon group, n = 0, 1, 2, or 3] can be used. In particular, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane are preferably used.

  As an addition method, a solution obtained by adding a small amount of alkali or acid as a catalyst to a mixed solution of these alkoxysilane, pure water, and alcohol is added to the dispersion of the porous particles, and the alkoxysilane is hydrolyzed. The produced silicic acid polymer is deposited on the surface of the inorganic oxide particles. At this time, alkoxysilane, alcohol, and catalyst may be simultaneously added to the dispersion. As the alkali catalyst, ammonia, an alkali metal hydroxide, or an amine can be used. As the acid catalyst, various inorganic acids and organic acids can be used.

  When the dispersion medium of the porous particle precursor is water alone or when the ratio of water to the organic solvent is high, a silica protective film can be formed using a silicic acid solution. When a silicic acid solution is used, a predetermined amount of the silicic acid solution is added to the dispersion, and at the same time an alkali is added to deposit the silicic acid solution on the surface of the porous particles. In addition, you may produce a silica protective film together using a silicic acid liquid and the said alkoxysilane.

Third Step: Formation of Silica Coating Layer In the third step, a hydrolyzable organosilicon compound or silicic acid solution is added to the porous particle dispersion prepared in the second step (in the case of hollow particles, a hollow particle precursor dispersion). Etc. is added to coat the surface of the particles with a polymer such as a hydrolyzable organosilicon compound or silicic acid solution to form a silica coating layer.

The hydrolyzable organic silicon compound used for the silica coating layer formed, the above-mentioned such general formula _{R n Si (OR ') 4} - n [R, R': an alkyl group, an aryl group, a vinyl group, An alkoxysilane represented by a hydrocarbon group such as an acryl group, n = 0, 1, 2, or 3] can be used. In particular, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane are preferably used.

  As an addition method, a solution obtained by adding a small amount of alkali or acid as a catalyst to a mixed solution of these alkoxysilane, pure water, and alcohol is used as a dispersion of the porous particles (in the case of hollow particles, a hollow particle precursor). In addition, the silicic acid polymer produced by hydrolyzing alkoxysilane is deposited on the surface of the porous particles (in the case of hollow particles, hollow particle precursors). At this time, alkoxysilane, alcohol, and catalyst may be simultaneously added to the dispersion. As the alkali catalyst, ammonia, an alkali metal hydroxide, or an amine can be used. As the acid catalyst, various inorganic acids and organic acids can be used.

  When the dispersion medium of porous particles (in the case of hollow particles, the hollow particle precursor) is water alone or a mixed solvent with an organic solvent and the mixed solvent has a high ratio of water to the organic solvent, a silicate solution You may form a coating layer using. The silicic acid solution is an aqueous solution of a low silicic acid polymer obtained by dealkalizing an aqueous solution of an alkali metal silicate such as water glass by ion exchange treatment.

  The silicic acid solution is added to the dispersion of porous particles (in the case of hollow particles, hollow particle precursors), and at the same time, alkali is added to make the low-silicic acid polymer into porous particles (in the case of hollow particles, hollow particle precursors). ) Deposit on the surface. A silicic acid solution may be used in combination with the alkoxysilane for forming a coating layer. The addition amount of the organosilicon compound or silicic acid solution used for forming the coating layer only needs to be sufficient to cover the surface of the colloidal particles, and the finally obtained silica coating layer has a thickness of 1 to 20 nm. In such an amount, it is added in a dispersion of porous particles (in the case of hollow particles, hollow particle precursor) in a dispersion. When the silica protective film is formed, the organosilicon compound or the silicate solution is added in such an amount that the total thickness of the silica protective film and the silica coating layer is in the range of 1 to 20 nm.

  Next, the dispersion liquid of the particles on which the coating layer is formed is heat-treated. By the heat treatment, in the case of porous particles, the silica coating layer covering the surface of the porous particles is densified, and a dispersion of composite particles in which the porous particles are coated with the silica coating layer is obtained. In the case of a hollow particle precursor, the formed coating layer is densified to form hollow particle walls, and a dispersion of hollow particles having cavities filled with a solvent, gas, or porous solid content is obtained.

  The heat treatment temperature at this time is not particularly limited as long as it can close the fine pores of the silica coating layer, and is preferably in the range of 80 to 300 ° C. When the heat treatment temperature is less than 80 ° C., the fine pores of the silica coating layer may not be completely closed and densified, and the treatment time may take a long time. Further, when the heat treatment temperature exceeds 300 ° C. for a long time, fine particles may be formed, and the effect of low refractive index may not be obtained.

  The refractive index of the inorganic fine particles thus obtained is as low as less than 1.44. Such inorganic fine particles are presumed to have a low refractive index because the porosity inside the porous particles is maintained or the inside is hollow.

The low refractive index layer used in the present invention preferably contains a hydrolyzate of an alkoxysilicon compound and a condensate formed by a subsequent condensation reaction in addition to the hollow fine particles. In particular, it is preferable to contain a SiO ₂ sol prepared by adjusting an alkoxysilicon compound represented by the following general formula (1) and / or (2) or a hydrolyzate thereof.

General formula (1) R ₁ —Si (OR ₂ ) ₃
General formula (2) Si (OR ₂ ) ₄
(Wherein R ₁ represents a methyl group, an ethyl group, a vinyl group, or an organic group containing an acryloyl group, a methacryloyl group, an amino group or an epoxy group, and R ₂ represents a methyl group or an ethyl group)
Hydrolysis of the silicon alkoxide and silane coupling agent is performed by dissolving the silicon alkoxide and silane coupling agent in a suitable solvent. Examples of the solvent to be used include ketones such as methyl ethyl ketone, alcohols such as methanol, ethanol and isopropyl alcohol butanol, esters such as ethyl acetate, and mixtures thereof.

  To a solution obtained by dissolving the silicon alkoxide or silane coupling agent in a solvent, an amount of water slightly larger than the amount necessary for hydrolysis is added, and the temperature is 15 to 35 ° C., preferably 20 to 30 ° C. for 1 to 48 hours. Stirring is preferably performed for 3 to 36 hours.

  In the hydrolysis, it is preferable to use a catalyst. As such a catalyst, an acid such as hydrochloric acid, nitric acid, sulfuric acid or acetic acid is preferably used. These acids are used in an aqueous solution of about 0.001N to 20.0N, preferably about 0.005 to 5.0N. The water in the catalyst aqueous solution can be water for hydrolysis.

  The alkoxy silicon compound is hydrolyzed for a predetermined time, the prepared alkoxy silicon hydrolyzed solution is diluted with a solvent, and other necessary additives are mixed to prepare a coating solution for a low refractive index layer. The low refractive index layer can be formed on the substrate by applying and drying on a substrate such as a film.

<Alkoxy silicon compound>
In the present invention, the alkoxysilicon compound (hereinafter also referred to as alkoxysilane) used for the preparation of the low refractive index layer coating solution is preferably represented by the following general formula (3).

General formula (3) R4-nSi (OR ') n
In the general formula, R ′ represents an alkyl group, R represents a hydrogen atom or a monovalent substituent, and n represents 3 or 4.

  Examples of the alkyl group represented by R ′ include groups such as a methyl group, an ethyl group, a propyl group, and a butyl group, which may have a substituent, and the substituent exhibits properties as an alkoxysilane. If it is, there is no restriction | limiting in particular, For example, although you may substitute by halogen atoms, such as a fluorine, an alkoxy group, etc., More preferably, it is an unsubstituted alkyl group, and especially a methyl group and an ethyl group are preferable.

  The monovalent substituent represented by R is not particularly limited, and examples thereof include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aromatic heterocyclic group, and a silyl group. Of these, an alkyl group, a cycloalkyl group, and an alkenyl group are preferable. These may be further substituted. Examples of the substituent for R include a halogen atom such as a fluorine atom and a chlorine atom, an amino group, an epoxy group, a mercapto group, a hydroxyl group, and an acetoxy group.

Specific preferred examples of the alkoxysilane represented by the general formula include tetramethoxysilane, tetraethoxysilane (TEOS), tetra n-propoxy silane, tetraisopropoxy silane, tetra n-butoxy silane, tetra t- Butoxysilane, tetrakis (methoxyethoxy) silane, tetrakis (methoxypropoxy) silane,
Further, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-butyltrimethoxysilane, i-butyltrimethoxysilane, n-hexyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3 -Mercaptopropyltrimethoxysilane, acetoxytriethoxysilane, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, (3, 3, - trifluoropropyl) trimethoxysilane, pentafluorophenyl phenylpropyl trimethoxysilane, further, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane and the like.

  Alternatively, quantified silicon compounds such as silicate 40, silicate 45, silicate 48, and M silicate 51 manufactured by Tama Chemical, in which these compounds are partially condensed may be used.

  Since the alkoxysilane has a silicon alkoxide group that can be hydrolyzed and polycondensed, these alkoxysilanes are crosslinked by hydrolysis and condensation to form a network structure of the polymer compound. A layer containing uniform silicon oxide is formed on the base material by applying it on the base material and drying it as a refractive index layer coating solution.

  The hydrolysis reaction can be performed by a known method. In order to easily mix the hydrophobic alkoxysilane with water, a predetermined amount of water and a hydrophilic organic solvent such as methanol, ethanol, and acetonitrile coexist and dissolve. -After mixing, a hydrolysis catalyst is added to hydrolyze and condense the alkoxysilane. Usually, by carrying out hydrolysis and condensation reaction at 10 ° C. to 100 ° C., a liquid silicate oligomer having two or more hydroxyl groups is generated, and a hydrolyzed solution is formed. The degree of hydrolysis can be appropriately adjusted depending on the amount of water used.

  In the present invention, as a solvent to be added to alkoxysilane together with water, methanol and ethanol are preferable because they are inexpensive and the properties of the resulting film are excellent and the hardness is good. Although isopropanol, n-butanol, isobutanol, octanol, and the like can be used, the hardness of the obtained film tends to be low. The amount of the solvent is 50 to 400 parts by mass, preferably 100 to 250 parts by mass with respect to 100 parts by mass of the tetraalkoxysilane before hydrolysis.

  In this way, a hydrolyzed solution is prepared, diluted with a solvent, and if necessary, an additive is added and mixed with components necessary to form a low refractive index layer coating solution. A coating solution is used.

<Hydrolysis catalyst>
Examples of the hydrolysis catalyst include acids, alkalis, organic metals, metal alkoxides, etc. In the present invention, inorganic acids or organic acids such as sulfuric acid, hydrochloric acid, nitric acid, hypochlorous acid, and boric acid are preferable, In particular, carboxylic acids such as nitric acid and acetic acid, polyacrylic acid, benzenesulfonic acid, paratoluenesulfonic acid, methylsulfonic acid, and the like are preferable, and among these, nitric acid, acetic acid, citric acid, tartaric acid, and the like are preferably used. In addition to the citric acid and tartaric acid, levulinic acid, formic acid, propionic acid, malic acid, succinic acid, methyl succinic acid, fumaric acid, oxaloacetic acid, pyruvic acid, 2-oxoglutaric acid, glycolic acid, D-glyceric acid, D- Gluconic acid, malonic acid, maleic acid, oxalic acid, isocitric acid, lactic acid and the like are also preferably used.

  Of these, those which volatilize the acid during drying and do not remain in the film are preferred, and those having a low boiling point are preferred. Therefore, acetic acid and nitric acid are particularly preferable.

  The added amount is 0.001 to 10 parts by mass, preferably 0.005 to 5 parts by mass with respect to 100 parts by mass of the alkoxysilicon compound (for example, tetraalkoxysilane) to be used. In addition, the amount of water added may be equal to or greater than the amount that the partial hydrolyzate can theoretically hydrolyze to 100%, and an amount equivalent to 100 to 300%, preferably an amount equivalent to 100 to 200% is added.

  When the alkoxysilane is hydrolyzed, the following inorganic fine particles are preferably mixed.

  The hydrolysis solution is allowed to stand for a predetermined time after the start of hydrolysis, and used after the progress of hydrolysis reaches a predetermined level. The standing time is a time during which the above-described crosslinking by hydrolysis and condensation proceeds sufficiently to obtain desired film characteristics. Specifically, depending on the type of acid catalyst used, for example, acetic acid is preferably 15 hours or more at room temperature, and nitric acid is preferably 2 hours or more. The aging temperature affects the aging time. Generally, the aging proceeds quickly at high temperatures, but when heated to 100 ° C. or higher, gelation occurs, so heating at 20 to 60 ° C. and keeping the temperature are appropriate.

  The above-mentioned hollow fine particles and additives are added to the silicate oligomer solution formed by hydrolysis and condensation in this way, and necessary dilution is performed to prepare a low refractive index layer coating solution, which is applied onto the above-described film. By drying, a layer containing an excellent silicon oxide film as the low refractive index layer can be formed.

  In the present invention, in addition to the above alkoxysilane, for example, a modified product modified with a silane compound (monomer, oligomer, polymer) having a functional group such as an epoxy group, an amino group, an isocyanate group, or a carboxyl group. It may be used alone or in combination.

<Fluorine compound>
The low refractive index layer used in the present invention preferably contains hollow fine particles and a fluorine compound, and as a binder matrix, a fluorine-containing resin that is crosslinked by heat or ionizing radiation (hereinafter also referred to as “fluorine-containing resin before crosslinking”). It is preferable to contain. By including the fluorine-containing resin, a good antifouling antireflection film can be provided.

  Preferred examples of the fluorine-containing resin before crosslinking include a fluorine-containing copolymer formed from a fluorine-containing vinyl monomer and a monomer for imparting a crosslinkable group. Specific examples of the fluorine-containing vinyl monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3 -Dioxoles, etc.), (meth) acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (produced by Osaka Organic Chemicals) or M-2020 (produced by Daikin)), fully or partially fluorinated vinyl ethers, etc. Is mentioned. As monomers for imparting a crosslinkable group, glycidyl methacrylate, vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinyl glycidyl ether, and other vinyl monomers having a crosslinkable functional group in advance in the molecule. , Vinyl monomers having a carboxyl group, hydroxyl group, amino group, sulfonic acid group, etc. (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyalkyl vinyl ether, hydroxyalkyl allyl) Ether, etc.). In the latter, it is possible to introduce a crosslinked structure by adding a compound having a group that reacts with a functional group in the polymer and one or more reactive groups after copolymerization, as disclosed in JP-A-10-25388 and 10-147739. In the issue. Examples of the crosslinkable group include acryloyl, methacryloyl, isocyanate, epoxy, aziridine, oxazoline, aldehyde, carbonyl, hydrazine, carboxyl, methylol, and active methylene group. When the fluorine-containing copolymer is cross-linked by heating by a cross-linking group that reacts by heating, or a combination of an ethylenically unsaturated group and a thermal radical generator or an epoxy group and a thermal acid generator, the thermosetting type In the case of crosslinking by irradiation with light (preferably ultraviolet rays, electron beams, etc.) by a combination of an ethylenically unsaturated group and a photo radical generator, or an epoxy group and a photo acid generator, etc., it is an ionizing radiation curable type. .

  In addition to the above monomers, a fluorine-containing copolymer formed by using a monomer other than the fluorine-containing vinyl monomer and the monomer for imparting a crosslinkable group may be used as the fluorine-containing resin before crosslinking. The monomer that can be used in combination is not particularly limited. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, 2-acrylic acid 2- Ethyl hexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl vinyl ether) Etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate, etc.), acrylamides (N-tertbutylacrylamide, N-cyclohexylacrylamide, etc.), methacrylamides, Ronitoriru derivatives and the like can be mentioned. In addition, it is also preferable to introduce a polyorganosiloxane skeleton or a perfluoropolyether skeleton into the fluorinated copolymer in order to impart slipperiness and antifouling properties. For example, polyorganosiloxane or perfluoropolyether having an acrylic group, methacrylic group, vinyl ether group, styryl group or the like at the terminal is polymerized with the above monomer, and polyorganosiloxane or perfluoropolyester having a radical generating group at the terminal. It can be obtained by polymerization of the above monomers with ether, reaction of a polyorganosiloxane or perfluoropolyether having a functional group with a fluorine-containing copolymer, or the like.

  The proportion of each of the above monomers used to form the fluorinated copolymer before crosslinking is preferably 20 to 70 mol%, more preferably 40 to 70 mol%, more preferably 40 to 70 mol% of the fluorinated vinyl monomer. The amount of the monomer is preferably 1 to 20 mol%, more preferably 5 to 20 mol%, and the other monomer used in combination is preferably 10 to 70 mol%, more preferably 10 to 50 mol%.

  The fluorine-containing copolymer can be obtained by polymerizing these monomers in the presence of a radical polymerization initiator by means such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization.

  The fluorine-containing resin before crosslinking is commercially available and can be used. Examples of commercially available fluorine-containing resins before cross-linking include Cytop (Asahi Glass), Teflon (registered trademark) AF (DuPont), polyvinylidene fluoride, Lumiflon (Asahi Glass), Opstar (JSR), etc. Can be mentioned.

  The low refractive index layer containing a cross-linked fluororesin as a constituent component preferably has a dynamic friction coefficient in the range of 0.03 to 0.15 and a contact angle with water in the range of 90 to 120 degrees.

<Additive>
The low refractive index layer coating solution may further contain additives such as a silane coupling agent and a curing agent as necessary. The silane coupling agent is a compound represented by the general formula (2).

  Specific examples include vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and 3- (2-aminoethylaminopropyl) trimethoxysilane.

  Examples of the curing agent include organic acid metal salts such as sodium acetate and lithium acetate, and sodium acetate is particularly preferable. The amount of addition to the silicon alkoxysilane hydrolysis solution is preferably in the range of about 0.1 to 1 part by mass with respect to 100 parts by mass of the solid content present in the hydrolysis solution.

  Moreover, it is preferable to add low surface tension substances such as various leveling agents, surfactants, and silicone oils to the coating solution for the low refractive index layer used in the present invention.

  Specific examples of the silicone oil include L-45, L-9300, FZ-3704, FZ-3703, FZ-3720, FZ-3786, FZ-3501, and FZ-3504 of Nippon Unicar Co., Ltd. , FZ-3508, FZ-3705, FZ-3707, FZ-3710, FZ-3750, FZ-3760, FZ-3785, FZ-3785, Y-7499, Shin-Etsu Chemical KF96L, KF96, KF96H, KF99, KF54 , KF965, KF968, KF56, KF995, KF351, KF352, KF353, KF354, KF355, KF615, KF618, KF945, KF6004, FL100 and the like.

  These components enhance the applicability to the substrate and the lower layer. When added to the outermost surface layer of the laminate, it not only improves the water repellency, oil repellency and antifouling properties of the coating film, but also exhibits an effect on the scratch resistance of the surface. When these components are added in an excessive amount, they cause repelling during coating. Therefore, it is preferable to add them in a range of 0.01 to 3% by mass with respect to the solid component in the coating solution.

<solvent>
Solvents used in the coating solution for coating the low refractive index layer are alcohols such as methanol, ethanol, 1-propanol, 2-propanol and butanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; benzene, toluene, Aromatic hydrocarbons such as xylene; glycols such as ethylene glycol, propylene glycol, hexylene glycol; ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, diethyl cellosolve, diethyl carbitol, propylene glycol monomethyl Examples include glycol ethers such as ethers; N-methylpyrrolidone, dimethylformamide, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, water, and the like. These may be used alone or in combination of two or more. Kill.

<Application method>
As a method of applying the low refractive index layer, known methods such as dipping, spin coating, knife coating, bar coating, air doctor coating, blade coating, squeeze coating, reverse roll coating, gravure roll coating, curtain coating, spray coating, die coating, etc. A coating method or a known inkjet method can be used, and a coating method capable of continuous coating or thin film coating is preferably used. The coating amount is suitably 0.1 to 30 μm, preferably 0.5 to 15 μm in terms of wet film thickness. The coating speed is preferably 10 to 80 m / min.

  When the composition of the present invention is applied to a substrate, the thickness of the layer, coating uniformity, and the like can be controlled by adjusting the solid content concentration and the coating amount in the coating solution.

  In the present invention, it is also preferable to further provide the following medium refractive index layer and high refractive index layer to form an antireflection layer having a plurality of layers.

  Although the structural example of the antireflection layer which can be used for this invention is shown below, it is not limited to these.

Cellulose ester film / hard coat layer / low refractive index layer Cellulose ester film / hard coat layer / medium refractive index layer / low refractive index layer Cellulose ester film / hard coat layer / high refractive index layer / low refractive index layer Cellulose ester film / Hard coat layer / Medium refractive index layer / High refractive index layer / Low refractive index layer Cellulose ester film / Antistatic layer / Hard coat layer / Medium refractive index layer / High refractive index layer / Low refractive index layer Cellulose ester film / Hard coat Layer / antistatic layer / medium refractive index layer / high refractive index layer / low refractive index layer antistatic layer / cellulose ester film / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index layer cellulose ester film / Hard coat layer / high refractive index layer / low refractive index layer / high refractive index layer / low refractive index layer (medium refractive index layer, high refractive index layer)
The medium refractive index layer and the high refractive index layer are not particularly limited as long as a predetermined refractive index layer is obtained, but are preferably composed of metal oxide fine particles, a binder and the like having the following high refractive index. In addition, you may contain an additive. The refractive index of the middle refractive index layer is preferably 1.55 to 1.75, and the refractive index of the high refractive index layer is preferably 1.75 to 2.20. The thickness of the high refractive index layer and the medium refractive index layer is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.1 μm. The coating can be performed in the same manner as the coating method for the low refractive index layer.

<Metal oxide fine particles>
Although metal oxide fine particles are not particularly limited, for example, titanium dioxide, aluminum oxide (alumina), zirconium oxide (zirconia), zinc oxide, antimony-doped tin oxide (ATO), antimony pentoxide, indium-tin oxide (ITO), Iron oxide or the like can be used as a main component. A mixture of these may also be used. When titanium dioxide is used, photocatalytic activity can be achieved by using metal oxide particles having a core / shell structure in which titanium dioxide is the core and the shell is coated with alumina, silica, zirconia, ATO, ITO, antimony pentoxide, or the like. It is preferable in terms of suppression.

  The refractive index of the metal oxide fine particles is preferably 1.80 to 2.60, more preferably 1.90 to 2.50. The average particle diameter of the primary particles of the metal oxide fine particles is 5 nm to 200 nm, more preferably 10 to 150 nm. If the particle size is too small, the metal oxide fine particles tend to aggregate and the dispersibility deteriorates. If the particle size is too large, the haze increases, which is not preferable. The shape of the inorganic fine particles is preferably a rice grain shape, a needle shape, a spherical shape, a cubic shape, a spindle shape or an indefinite shape.

  The metal oxide fine particles may be surface-treated with an organic compound. Examples of the organic compound used for the surface treatment include polyols, alkanolamines, stearic acid, silane coupling agents, and titanate coupling agents. Among these, the silane coupling agent described later is most preferable. Two or more kinds of surface treatments may be combined.

  By appropriately selecting the kind and addition ratio of the metal oxide, a high refractive index layer and a medium refractive index layer having a desired refractive index can be obtained.

<Binder>
The binder is added to improve the film formability and physical properties of the coating film. As the binder, for example, the aforementioned ionizing radiation curable resin, acrylamide derivative, polyfunctional acrylate, acrylic resin or methacrylic resin can be used.

(Metal compounds, silane coupling agents)
As other additives, a metal compound, a silane coupling agent, and the like may be added. Metal compounds and silane coupling agents can also be used as binders.

  As the metal compound, a compound represented by the following general formula (4) or a chelate compound thereof can be used.

Formula (4): A _n MB _x−n
In the formula, M represents a metal atom, A represents a hydrolyzable functional group or a hydrocarbon group having a hydrolyzable functional group, and B represents an atomic group covalently or ionically bonded to the metal atom M. x represents the valence of the metal atom M, and n represents an integer of 2 or more and x or less.

  Examples of the hydrolyzable functional group A include halogens such as alkoxyl groups and chloro atoms, ester groups and amide groups. The metal compound belonging to the above formula (4) includes an alkoxide having two or more alkoxyl groups bonded directly to a metal atom, or a chelate compound thereof. Preferable metal compounds include titanium alkoxides, zirconium alkoxides, silicon alkoxides or chelate compounds thereof from the viewpoints of the reinforcing effect of refractive index and coating film strength, ease of handling, material cost, and the like. Titanium alkoxide has a high reaction rate and a high refractive index and is easy to handle. However, since it has a photocatalytic action, its light resistance deteriorates when added in a large amount. Zirconium alkoxide has a high refractive index but tends to become cloudy, so care must be taken in dew point management during coating. Silicon alkoxide has a slow reaction rate and a low refractive index, but is easy to handle and has excellent light resistance. Since the silane coupling agent can react with both the inorganic fine particles and the organic polymer, a tough coating film can be formed. Moreover, since titanium alkoxide has the effect of promoting the reaction between the ultraviolet curable resin and the metal alkoxide, the physical properties of the coating film can be improved even by adding a small amount.

  Examples of the titanium alkoxide include tetramethoxy titanium, tetraethoxy titanium, tetra-iso-propoxy titanium, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetra-sec-butoxy titanium, tetra-tert-butoxy titanium, and the like. Is mentioned.

  Examples of the zirconium alkoxide include tetramethoxy zirconium, tetraethoxy zirconium, tetra-iso-propoxy zirconium, tetra-n-propoxy zirconium, tetra-n-butoxy zirconium, tetra-sec-butoxy zirconium, tetra-tert-butoxy zirconium and the like. Is mentioned.

  The silicon alkoxide and the silane coupling agent are compounds represented by the following general formula (5).

Formula _{(5): R m Si (} OR ') n
In the formula, R is an alkyl group (preferably an alkyl group having 1 to 10 carbon atoms), or a reaction such as a vinyl group, a (meth) acryloyl group, an epoxy group, an amide group, a sulfonyl group, a hydroxyl group, a carboxyl group, or an alkoxyl group. R ′ represents an alkyl group (preferably an alkyl group having 1 to 10 carbon atoms), and m + n is 4.

  Specifically, tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, tetrapenta Ethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, hexyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane , Γ-glycidoxypropyltrimethoxysilane, 3- (2-aminoethylaminopropyl) trimethoxysilane and the like.

  Preferred chelating agents for coordination with free metal compounds to form chelate compounds include alkanolamines such as diethanolamine and triethanolamine, glycols such as ethylene glycol, diethylene glycol and propylene glycol, acetylacetone and acetoacetate Examples thereof include ethyl and the like having a molecular weight of 10,000 or less. By using these chelating agents, it is possible to form a chelate compound that is stable against water mixing and is excellent in the effect of reinforcing the coating film.

  The addition amount of the metal compound is preferably less than 5% by mass in terms of metal oxide in the medium refractive index composition, and less than 20% by mass in terms of metal oxide in the high refractive index composition. Is preferred.

  For the adhesion treatment between the polarizer and the transparent protective film, an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, a water-based polyester, or the like is used.

As the retardation film (3), those having an Nz ₃ value of 0 to 0.35 and an in-plane retardation value Re ₃ of 60 to 450 nm can be used without particular limitation. Examples thereof include a birefringent film of a polymer film and an alignment film of a liquid crystal polymer.

  Examples of the high molecular polymer include polyolefins such as polycarbonate and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, alicyclic polyolefins such as polynorbornene, polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxy Ethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyarylate, polysulfone, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyallyl sulfone, polyvinyl alcohol, polyamide, polyimide, polyvinyl chloride, cellulose polymer, or a binary system thereof , Various terpolymers, graft copolymers, blends, etc. . The retardation film controls the refractive index in the thickness direction by a method of stretching a polymer film biaxially in the plane direction, a method of stretching uniaxially or biaxially in the plane direction, and stretching in the thickness direction, etc. Can be obtained. Further, it can be obtained by, for example, a method in which a heat-shrinkable film is bonded to a polymer film, and the polymer film is stretched or / and contracted by tilting under the action of the shrinkage force by heating.

  Examples of the liquid crystalline polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of the main chain type liquid crystalline polymer include nematic alignment polyester liquid crystalline polymer, discotic polymer, cholesteric polymer and the like having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. . Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. The alignment films of these liquid crystalline polymers are, for example, liquid crystalline polymers on alignment-treated surfaces such as those obtained by rubbing the surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or those obtained by obliquely depositing silicon oxide. A solution in which the liquid crystal polymer is oriented by developing and heat-treating the above solution, and particularly in a tilted orientation, is preferred.

As the retardation film (4), those having the Nz ₄ value of 0.8 to 1.2 and the in-plane retardation value Re ₄ of 60 to 450 nm can be used without any particular limitation. What was illustrated by the film (3) can be used similarly.

  The method for laminating the retardation film and the polarizing plate is not particularly limited, and can be performed using an adhesive layer or the like. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency, such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and having excellent weather resistance, heat resistance and the like can be preferably used.

  For each layer such as an optical film or an adhesive layer, for example, a method of treating with an ultraviolet absorber such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound, etc. The thing etc. which gave the ultraviolet absorptivity may be sufficient.

  The optical film according to the present invention is suitably used for an IPS mode liquid crystal display device. An IPS mode liquid crystal display device includes: a pair of substrates sandwiching a liquid crystal layer; an electrode group formed on one of the pair of substrates; a liquid crystal composition material layer having dielectric anisotropy sandwiched between the substrates; A liquid crystal cell comprising: an alignment control layer formed opposite to the pair of substrates for aligning molecular alignment of the liquid crystal composition material in a predetermined direction; and driving means for applying a driving voltage to the electrode group Have The electrode group has an arrangement structure arranged so as to apply mainly a parallel electric field to the interface between the alignment control layer and the liquid crystal composition material layer. As described above, the liquid crystal cell preferably has a retardation value at 550 nm of 230 to 360 nm when no voltage is applied.

  As shown in FIG. 2, the transmissive liquid crystal display device of the present invention has the polarizing plate (1) such that the absorption axis of the polarizing plate (1) and the slow axis of the retardation film (3) are orthogonal or parallel. 1) and the retardation film (3) are laminated to form an optical film (1) so that the absorption axis of the polarizing plate (2) and the slow axis of the retardation film (4) are orthogonal or parallel. When an optical film (2) is formed by laminating the polarizing plate (2) and the retardation film (4), the absorption axes of the polarizing plate (1) and the polarizing plate (2) are in an orthogonal state. Moreover, it is preferable to arrange | position the said optical film (1) and the said optical film (2) on both surfaces of the said liquid crystal cell, respectively.

  In addition, as shown in FIG. 2, the optical film (1) is arranged on the cell substrate on the viewing side, and the optical film (2) is arranged on the cell substrate on the incident side. It is preferable that the extraordinary refractive index direction of the liquid crystal substance in the cell and the absorption axis of the polarizing plate on the incident side are in a parallel state.

  Similarly, as shown in FIG. 2, the optical film (1) is laminated so that the absorption axis of the polarizer and the slow axis of the retardation film (3) are parallel, and the optical film (2 ) Is preferably laminated so that the absorption axis of the polarizer and the slow axis of the retardation film (4) are parallel to each other.

  The optical film and the polarizing plate can be used by laminating other optical layers in practical use. The optical layer is not particularly limited. For example, one optical layer that may be used for forming a liquid crystal display device such as a phase difference plate (including a wave plate such as 1/2 or 1/4) is used. Two or more layers can be used. In particular, a polarizing plate in which a brightness enhancement film is further laminated on the polarizing plate is preferable.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light into elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light into linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for compensating (preventing) coloring (blue or yellow, etc.) caused by birefringence of the liquid crystal layer of the liquid crystal display device and displaying black and white without the coloring. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which the image is displayed in color, and also has an antireflection function.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects the linearly polarized light of a predetermined polarization axis or circularly polarized light in a predetermined direction when natural light is incident due to a backlight of a liquid crystal display device or the like, or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer provided on the rear side thereof and re-incident on the brightness enhancement film, and a part or all of the light is transmitted as light in a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and then inverted through a reflective layer or the like provided behind the brightness enhancement film. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed toward the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., the brightness unevenness of the display screen is reduced at the same time, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. As shown (made by 3M, D-BEF, etc.), the orientation film of the cholesteric liquid crystal polymer and the oriented liquid crystal layer supported on the film substrate (made by Nitto Denko, PCF350, Merck, Transmax, etc.), Any suitable one can be used, such as one that reflects either left-handed or right-handed circularly polarized light and transmits other light.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on a polarizer. However, in order to suppress absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation layer that functions as a quarter-wave plate for light-color light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method of superposing a retardation layer, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, the cholesteric liquid crystal layer can also be obtained by reflecting circularly polarized light in a wide wavelength range such as the visible light region by combining two or more layers with different reflection wavelengths and having an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or more optical layers as in the above-described polarization separation type polarizing plate. Accordingly, a reflective elliptical polarizing plate, a semi-transmissive elliptical polarizing plate, or the like, which is a combination of the above-described reflective polarizing plate or transflective polarizing plate and a retardation plate, may be used.

  The optical film and the polarizing plate on which the optical layer is laminated can be formed by a method of sequentially laminating sequentially in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics and the like.

  The liquid crystal display device can be formed according to a conventional method. The liquid crystal display device is generally formed by appropriately assembling components such as an illumination system as necessary and incorporating a drive circuit, etc., but there is no particular limitation except that the optical film is used in the present invention. The conventional method can be applied. As the liquid crystal cell, an arbitrary type such as a VA type or a π type can be used in addition to the IPS mode exemplified above.

  As the liquid crystal display device, an appropriate liquid crystal display device such as one using an illumination system or a reflector can be formed. Further, when forming a liquid crystal display device, for example, a single layer or a suitable layer of an appropriate component such as a diffuser plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffuser plate, a backlight, etc. Two or more layers can be arranged.

[Cellulose ester film]
In the present invention, the transparent protective film (1-1, 1-2, 2-1, 2-2) is preferably a cellulose ester film.

  Examples of the cellulose ester include cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, and cellulose acetate propionate. In the case of cellulose triacetate, cellulose triacetate having a polymerization degree of 250 to 400 and a bound acetic acid amount of 54 to 62.5% is particularly preferable, and a bound acetic acid amount of 58 to 62.5% is more preferable because of high mechanical strength. As the cellulose triacetate, either cellulose triacetate synthesized from cotton linter or cellulose triacetate synthesized from wood pulp can be used alone or in combination. It is preferable to use a large amount of cellulose triacetate synthesized from a cotton linter that has good releasability from a belt or a drum because of high productivity efficiency. Since the ratio of cellulose triacetate synthesized from cotton linter is 60% by mass or more and the effect of releasability becomes remarkable, 60% by mass or more is preferable, more preferably 85% by mass or more, and further, it can be used alone. Most preferred.

  If the number average polymerization degree of the cellulose ester used in the present invention is too low, the strength will be low, and if it is too high, the viscosity of the solution may be too high, so 60000-300000 are preferred, and 80000-200000 are more preferred.

  About the specific manufacturing method of the cellulose ester used for this invention, it is compoundable by the method described in Unexamined-Japanese-Patent No. 10-45804, for example.

  Moreover, in order to obtain the target substitution ratio, it can also obtain by mixing 2 or more types after substituting a fixed amount with each kind of acyl group previously.

(Plasticizer)
The plasticizer used in the transparent protective film of the present invention is not particularly limited, but a functional group capable of interacting with a cellulose derivative by hydrogen bonding or the like so as not to generate haze or bleed out or volatilize from the film. It is preferable to have.

  Examples of such functional groups include hydroxyl groups, ether groups, carbonyl groups, ester groups, carboxylic acid residues, amino groups, imino groups, amide groups, imide groups, cyano groups, nitro groups, sulfonyl groups, sulfonic acid residues, Examples thereof include a phosphonyl group and a phosphonic acid residue, and a carbonyl group, an ester group and a phosphonyl group are preferred.

  Examples of such plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol plasticizers, glycolate plasticizers. Citric acid ester plasticizers, fatty acid ester plasticizers, carboxylic acid ester plasticizers, polyester plasticizers, and the like can be preferably used. These plasticizers can be used in combination as long as the effects of the present invention are not impaired.

<Polymer plasticizer>
A polymer plasticizer is preferably used for the cellulose ester used in the present invention. The polymer plasticizer preferably has a weight average molecular weight of at least 1000 or more.

  Moreover, in order to give a plastic effect to cellulose ester, Tg is preferably 50 ° C. or lower.

  Specific examples include polycarbonate, polyvinyl chloride, polyvinylidene chloride, acrylic resin, polycarboxylic acid ester, polystyrene, polyester, polyethylene, polypropylene, polyamide resin, and polyethersulfone. More preferably, an acrylic resin synthesized from a compound having an ethylenic double bond, or a polyvinyl carboxylate polymer.

(Polymer obtained by polymerizing a compound having an ethylenic double bond)
The cellulose ester used in the present invention preferably contains a polymer obtained by polymerizing a compound having a weight average molecular weight of 500 to 30,000 and having an ethylenic double bond. In particular, the transparent protective film (1-2) or (2-1) preferably contains a polymer obtained by polymerizing the compound having an ethylenic double bond.

  Examples of the compound having an ethylenic double bond include methyl (meth) acrylate, ethyl acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, Illustrated are (meth) acrylic acid esters such as isononyl (meth) acrylate, isomyristyl acrylate 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, ε-caprolactone (meth) acrylate, benzyl (meth) acrylate, etc. can do.

  Examples of vinyl carboxylate monomers include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, cyclohexanecarboxylate, vinyl bivalinate, Examples thereof include vinyl octylate divinyl adipate, vinyl methacrylate, vinyl crotonic acid, vinyl sorbate, vinyl benzoate and vinyl cinnamate.

  Examples of vinyl monomers other than the above include styrene, vinyl chloride, ethylene, propylene, (meth) acrylonitrile, N-vinylpyrrolidone, (meth) acrylic acid, maleic anhydride, crotonic acid, itaconic acid, and the like. Homopolymers or copolymers of the compounds can be used in the present invention.

  When the solubility of the polymer in a solvent is insufficient, a polar group such as a carboxyl group, a hydroxyl group or an amino group may be added.

  It is preferable to add 5-35 mass parts with respect to 100 mass parts, and, as for the addition amount of this polymer, it is more preferable to add 10-25 mass parts with respect to 100 mass parts.

  By adjusting the addition amount of the polymer and the production conditions, it is possible to obtain a transparent protective film in which the in-plane retardation Re is adjusted in the range of 0 to 5 nm and the thickness direction retardation Rth is adjusted in the range of -20 to 20 nm. I can do it.

(UV absorber)
The cellulose ester used in the present invention preferably contains an ultraviolet absorber. As the ultraviolet absorber, those having an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less and little absorption of visible light having a wavelength of 400 nm or more are preferably used. Specific examples of preferably used ultraviolet absorbers include triazine compounds, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. However, it is not limited to these. Moreover, the polymeric ultraviolet absorber described in JP-A-6-148430 is also preferably used.

  Specific examples of ultraviolet absorbers useful in the present invention include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butyl). -Phenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methyl-phenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butyl) -Phenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methyl-phenyl) benzotriazole, 2 , 2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2′-hydroxy -3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methyl-phenol << TINUVIN 171 >>, 2-octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3 -[3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate mixture << TINUVIN 109 >>, 2- (2H-benzotriazole -2yl) -4,6-bis (1-methyl-1-phenylethyl) phenol << Tinuvin 234 >> 2- (3-t- butyl-5-methyl-2-hydroxyphenyl) -5-chloro - benzotriazole << Tinuvin 326 >> like can be mentioned but not limited thereto. Moreover, any of the above-mentioned tinuvins such as tinuvin 109, tinuvin 171 and tinuvin 326 are commercially available products manufactured by Ciba Specialty Chemicals, Inc., and can be preferably used.

  Specific examples of benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy- 5-benzoylphenylmethane) and the like, but are not limited thereto.

  Moreover, since the ultraviolet absorber which can be used for the retardation film of this invention is excellent also in the applicability | paintability of various coating layers, the ultraviolet absorber with the distribution coefficient described in Unexamined-Japanese-Patent No. 2000-187825 is 9.2 or more. In particular, it is preferable to use an ultraviolet absorber having a distribution coefficient of 10.1 or more.

  Moreover, as an ultraviolet absorber, an ethylenic double bond containing ultraviolet absorber can be made into "the polymer obtained by superposing | polymerizing the compound which has an ethylenic double bond" using the following polymerization initiator. As an ethylenic double bond-containing ultraviolet absorber, it has an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal, and can absorb visible light having a wavelength of 400 nm or more from the viewpoint of good liquid crystal display properties. Therefore, a small amount is preferably used. It is necessary to copolymerize with the compound having an ethylenic double bond having an extinction coefficient ε of at least 5000 at 350 nm or more.

  Specific examples of the compound include, but are not limited to, a monomer in which a methacryloyl group is introduced into the benzotriazole skeleton (trade name: reactive UV absorber RUVA-93 (manufactured by Otsuka Chemical Co., Ltd.)).

(Antistatic agent)
The cellulose ester used in the present invention preferably contains an antistatic agent. As an antistatic agent, an ethylenic double bond-containing antistatic agent can be made into a “polymer obtained by polymerizing a compound having an ethylenic double bond” using the following polymerization initiator. Ethylenic double bond-containing antistatic agents include methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, quaternary ammonium base-containing (meth) acrylate, quaternary ammonium base-containing maleimide Examples include quaternary ammonium-containing methacrylimide and sodium styrene sulfonate.

  The cellulose ester used in the present invention preferably contains a polymer obtained by polymerizing a compound having an epoxy group or a vinyl ether group. Examples of the compound having an epoxy group or a vinyl ether group include bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, tetrabromobisphenol A diglycidyl ether, resorcinol diglycidyl ether, phthalic acid diglycidyl ester, cresol novolac polyglycidyl ether, Phenol novolac polyglycidyl ether etc. are mentioned.

(Polymerization initiator)
As the radical polymerization initiator used in the present invention, benzoin, benzoin methyl ether, benzoin-n-propyl ether, benzoin-n-butyl ether, benzyl, benzophenone, p-methylbenzophenone, diacetyl, eosin, thionine, Michler's ketone, acetophenone, 2-chlorothioxanthone, anthraquinone, chloroanthraquinone, 2-methylanthraquinone, α-hydroxyisobutylphenone, p-isopropyl-α-hydroxyisobutylphenone, α, α'-dichloro-4-phenoxyacetophenone, 1-hydroxy- 1-cyclohexylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, methylbenzoinformate, 2-methyl-1- [4- (methylthio) phenyl]- - it can be exemplified morpholinophenyl propene, dichloride thio xanthone, diisopropyl thioxanthone, phenyl disulfide 2-nitroso fluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide and the like.

  Examples of the cationic polymerization initiator include sulfur initiators such as triphenylsulfonium hexafluoride antimonate and onium salts typified by iodine initiators such as diphenyliodonium hexafluoride antimonate. One or two or more of these polymerization initiators can be used in combination.

(solvent)
Examples of solvents for additives such as cellulose ester, plasticizer, polymer obtained by polymerizing a compound having an ethylenic double bond include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol and the like. Lower aliphatic hydrocarbons such as cyclohexanedioxane and methylene chloride, acetone, ketones of methyl ethyl ketone, esters such as ethyl acetate and butyl acetate, aromatics such as toluene and xylene, etc. Can be used.

  The solvent ratio is preferably 88 to 96% by mass for methylene chloride and 4 to 12% by mass for other solvents. More preferably, methylene chloride is 90 to 94% by mass, and the other solvent is 6 to 10% by mass.

  The concentration of the cellulose ester and the plasticizer with respect to the entire dope is preferably 15 to 30% by mass. More preferably, it is 18-25 mass%.

  The concentration of the cellulose ester and the polymer with respect to the entire dope is preferably 15 to 30% by mass. More preferably, it is 18-25 mass%.

  The heating and melting temperature with the addition of the solvent is preferably a temperature that is not lower than the boiling point of the solvent used and does not boil, and is preferably set in the range of 60 ° C. or higher and 80 to 110 ° C., for example. The pressure is determined so that the solvent does not boil at the set temperature.

  After dissolution, it is taken out from the container while cooling, or extracted from the container with a pump or the like and cooled with a heat exchanger or the like, and used for film formation.

(Method for producing cellulose ester film)
The method for producing the cellulose ester film in the present invention is not particularly limited, and may be a method commonly used in the art. For example, U.S. Pat. Nos. 2,492,978, 2,739,070, and 2 No. 7,39,069, No. 2,492,977, No. 2,336,310, No. 2,367,603, No. 2,607,704, British Patent No. 64,071, Reference is made to the methods described in JP-B Nos. 735, 892, 45-9074, 49-4554, 49-5614, 60-27562, 61-39890, 62-4208, etc. Can be.

  Necessary additives in addition to the cellulose ester and the solvent may be mixed with the solvent in advance and dissolved or dispersed, and then added to the solvent before dissolving the cellulose ester, or may be added to the dope after dissolving the cellulose ester.

  The type of the pressure vessel is not particularly limited as long as it can withstand a predetermined pressure and can be heated and stirred under pressure. In addition to the pressure vessel, other instruments such as a pressure gauge and a thermometer are appropriately disposed.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or by increasing 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.

  After dissolution, take it out from the container while cooling, or take it out from the container with a pump and cool it with a heat exchanger, etc., and use it for film formation, but the cooling temperature at this time may be cooled to room temperature, It is more preferable to cool to a temperature lower by 5 to 10 ° C. than the boiling point and perform casting at that temperature because the dope viscosity can be reduced.

  In the present invention, a dope obtained by dissolving cellulose ester is cast on a support (casting process), and then heated to remove a part of the solvent (drying process on the support), and then from the support. It peels and the peeled film is dried (film drying process), and a cellulose-ester film is obtained.

  The film thickness of the cellulose ester film is 30 to 150 μm, preferably 30 to 60 μm.

  As the support in the casting process, a support in which a belt-like or drum-like stainless steel is mirror-finished is used. The temperature of the support in the casting step can be cast in a general temperature range of 0 ° C. to a temperature lower than the boiling point of the solvent, but the dope is gelled by casting on a support at 5 to 30 ° C. The separation limit time can be increased, and the casting is preferably cast on a support at 5 to 15 ° C. The peeling limit time is the time during which the cast dope is on the support at the limit of the casting speed at which a transparent and flat film can be continuously obtained. A shorter peeling limit time is preferable because of excellent productivity.

  In the drying process on the support, the dope is cast, once gelled, and when the time from casting to peeling is 100%, the dope temperature is set to 40 to 70 ° C. within 30% from casting. Thus, the evaporation of the solvent is promoted, and it can be peeled off from the support as quickly as possible, and the peel strength is further increased. The dope temperature is preferably set to 55 to 70 ° C. within 30%. This temperature is preferably maintained at 20% or more, more preferably 40% or more. Drying on the support is preferably peeled off from the support with a residual solvent amount of 30 to 150% because the peel strength from the support is reduced, more preferably 40 to 120%, and even more preferably 80 to 100%. %. The dope temperature at the time of peeling is preferably 0 to 30 ° C., since the base strength at the time of peeling can be increased and the base breakage at the time of peeling can be prevented, and 5 ° C. to 20 ° C. is more preferable.

  The amount of residual solvent in the film is represented by the following formula.

Residual solvent amount = residual volatile matter mass / film mass after heat treatment × 100%
The residual volatile matter mass is a value obtained by subtracting the film mass after the heat treatment from the film mass before the heat treatment when the film is heat treated at 115 ° C. for 1 hour.

  In the film drying step, the film peeled off from the support is further dried, and the residual solvent amount is 5% by mass or less, preferably 2% by mass or less, more preferably 0.5% by mass or less. It is preferable for obtaining a good film. In the film drying process, generally, a roll suspension system, a pin tenter system, or a clip tenter system is used for drying while transporting the film. For the liquid crystal display member, it is preferable to dry while maintaining the width or stretching by a tenter method in order to improve the dimensional stability. In particular, it is particularly preferable to hold the width where there is a large amount of residual solvent immediately after peeling from the support because the effect of improving the dimensional stability is more exhibited.

  In particular, in the drying process after peeling from the support, the film tends to shrink in the width direction due to evaporation of the solvent. Shrinkage increases with drying at higher temperatures. In order to improve the flatness of the finished film, it is preferable to dry while suppressing the shrinkage as much as possible. From this point, for example, a method / tenter method in which the entire drying process or a part of the drying process as shown in Japanese Patent Application Laid-Open No. 62-46625 is performed while holding the width at both ends of the web with a clip in the width direction. Is preferred.

  The means for drying the film is not particularly limited, and is generally performed with hot air, infrared rays, a heating roll, microwaves, or the like. It is preferable to carry out with hot air in terms of simplicity. The drying temperature is preferably divided into 3 to 5 stages in the range of 40 to 150 ° C., and gradually increased, and it is more preferably performed in the range of 80 to 140 ° C. in order to improve dimensional stability.

  These steps from casting to post-drying may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen gas. It goes without saying that the dry atmosphere is carried out in consideration of the explosion limit concentration of the solvent.

  The winder relating to the production of the cellulose ester film according to the present invention may be a commonly used winder such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, etc. It can be wound up by the method.

  The thickness of the cellulose ester film according to the present invention is preferably from 30 to 150 μm, more preferably from 30 to 60 μm, from the request of thinning and lightening the polarizing plate used in the LCD. If it is thinner than this, the stiffness of the film will be reduced, so that troubles due to the occurrence of wrinkles and the like are likely to occur in the polarizing plate production process, and if it is thicker than this, the contribution to thinning of the LCD is small.

  About the cellulose-ester film which concerns on this invention, it is preferable that the dimensional change rate after 50-hour processing by 80 degreeC and relative humidity 90% RH is -0.5 to + 0.5% in both a vertical direction and a horizontal direction. More preferably, it is -0.4 to + 0.4%, and still more preferably -0.3 to + 0.3%.

  About the cellulose-ester film which concerns on this invention, it is preferable that the curl value in 23 degreeC-80% RH is -20- + 40 (unit: 1 / m). More preferably, it is -20- + 35, More preferably, it is -20- + 25.

  About the cellulose ester which concerns on this invention, it is preferable that the curl value in 40 degreeC water is -20- + 60 (unit: 1 / m). More preferably, it is -20- + 50, More preferably, it is -20- + 40.

  In addition, fine particles such as silicon oxide may be added to the cellulose ester film according to the present invention as a matting agent if necessary. It is preferable that fine particles such as silicon oxide are surface-treated with an organic substance because the haze of the film can be reduced. Preferred organic materials for the surface treatment include halosilanes, alkoxysilanes, silazanes, siloxanes, and the like. The larger the average diameter of the fine particles, the greater the mat effect, and the smaller the average diameter, the better the transparency. Therefore, the average diameter of the primary particles of the fine particles is preferably 5 to 50 nm, more preferably 7 to 14 nm. Examples of the fine particles of silicon oxide include Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, etc. manufactured by Aerosil Co., preferably AEROSILR972, R974, R202, R812, and the like. .

  In the present invention, it is preferable that the cellulose ester film has less foreign matter. In particular, it is preferable that there are few foreign substances recognized under polarized crossed Nicols conditions.

  The foreign substance recognized in the polarization crossed Nicol state refers to that measured by placing two polarizing plates in a direct (crossed Nicol) state and placing a cellulose ester film between them. In the polarization crossed Nicol state, such a foreign substance is observed by shining only the part of the foreign substance in the dark field, so that the size and number can be easily identified.

As for the number of foreign matters, it is preferable that there are 200 or less foreign matters having a size of 5 to 50 μm recognized in a polarization crossed Nicol state and substantially 0 foreign matters having a size of 50 μm or more per 250 mm ² area. More preferably, the number of foreign matters of 5 to 50 μm is 100 or less, more preferably 50 or less.

  In order to obtain the above-mentioned cellulose ester film with few foreign substances, any means can be used, but it can be achieved by filtering a dope composition in which cellulose ester is dissolved in a solvent using the following filter paper. In this case, it is preferable to use a filter paper having a drainage time (according to JIS P3801 7.5) of 20 sec or more as a kind of filter paper, and to form a film by filtering at a filtration pressure of 1.6 MPa or less. More preferably, a filter paper of 30 sec or more is used, and the filtration pressure is 1.2 MPa or less, and more preferably, a filter paper of 40 sec or more is used and the filtration pressure is 1.0 MPa or less. Moreover, it is more preferable to use two or more of the above filter papers. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

(Polarizer)
The production method of the polarizing plate according to the present invention is not particularly limited, and can be produced by a general method. For example, there is a method in which a cellulose triacetate film is alkali-treated and bonded to both surfaces of a polarizer prepared by immersing and stretching in an iodine solution in advance using a completely saponified polyvinyl alcohol aqueous solution. Instead of the alkali treatment, a method for improving adhesiveness as described in JP-A-6-94915 and JP-A-6-118232 may be used.

(Ethylene-modified polyvinyl alcohol)
In the present invention, a polarizer obtained by stretching and dyeing ethylene-modified polyvinyl alcohol is preferably used. In particular, ethylene-modified polyvinyl alcohol having an ethylene unit content of 1 to 4 mol%, a polymerization degree of 2000 to 4000, and a saponification degree of 99.0 to 99.99 mol% is preferably used. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used. Further, it is more preferable that the difference in hot water cutting temperature between two points separated by 5 cm in the TD direction of the film is 1 ° C. or less, and further two points separated by 1 cm in the TD direction of the film. In order to reduce color spots, it is more preferable that the difference in hot water cutting temperature between them is 0.5 ° C. or less.

  Moreover, it is especially preferable when the film thickness is 5 to 20 μm in order to reduce color spots.

  A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has few color spots, and is particularly preferably used for an IPS large-sized liquid crystal display device.

  As the ethylene-modified polyvinyl alcohol (ethylene-modified polyvinyl alcohol) used in the present invention, an ethylene-vinyl ester polymer obtained by copolymerizing ethylene and a vinyl ester monomer is saponified, and the vinyl ester unit is converted into vinyl alcohol. A unit can be used. Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, and the like. Of these, vinyl acetate is preferably used.

  The ethylene unit content (ethylene copolymerization amount) in the ethylene-modified polyvinyl alcohol is 1 to 4 mol%, preferably 1.5 to 3 mol%, more preferably 2 to 3 mol%.

  When the content of the ethylene unit is within this range, the polarization performance and durability performance are improved, and color spots are reduced, which is preferable.

  Furthermore, the following monomers can be copolymerized with a vinyl ester monomer in ethylene-modified polyvinyl alcohol. When copolymerizing with a vinyl ester monomer, the preferred range is 15 mol% or less, more preferably 5 mol% or less.

  Examples of monomers copolymerizable with such vinyl ester monomers include olefins having 3 to 30 carbon atoms such as propylene, 1-butene and isobutene; acrylic acid and salts thereof; methyl acrylate, ethyl acrylate, Acrylic esters such as n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, etc. Methacrylic acid and salts thereof; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-methacrylic acid 2- Ethylhexyl, dodecyl methacrylate, methacrylic acid Methacrylic acid esters such as kutadecyl; acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and its salt, acrylamidopropyldimethylamine and its salt, N-methylol Acrylamide derivatives such as acrylamide and derivatives thereof; methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and salts thereof, methacrylamidepropyldimethylamine and salts thereof, N-methylolmethacrylamide and derivatives thereof Methacrylamide derivatives such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone and other N-vinylamides; methyl Vinyl ethers such as nyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid and its salts or esters thereof; itaconic acid and its salts or esters thereof; Vinylsilyl compounds such as methoxysilane; N-vinylamides such as isopropenyl acetate, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone it can.

  The degree of polymerization of ethylene-modified polyvinyl alcohol constituting the polarizer is 2000 to 4000 from the viewpoint of polarization performance and durability, preferably 2200 to 3500, and particularly preferably 2500 to 3000. When the degree of polymerization is less than 2000, the polarizing performance and durability performance of the polarizer are lowered, which is not preferable. Moreover, it is preferable that the polymerization degree is 4000 or less because color spots of the polarizer hardly occur.

  The degree of polymerization of ethylene-modified polyvinyl alcohol is the weight average degree of polymerization determined from GPC measurement. This weight average degree of polymerization is a value obtained by performing GPC measurement at 40 ° C. using hexafluoroisopropanol (HFIP) in which 20 mmol / liter sodium trifluoroacetate is added to the mobile phase using monodispersed PMMA as a standard. is there.

  The saponification degree of the ethylene-modified polyvinyl alcohol constituting the polarizer is 99.0 to 99.99 mol% from the viewpoint of the polarization performance and durability of the polarizer, and more preferably 99.9 to 99.99 mol%, 99.95-99.99 mol% is particularly preferable.

  Although it does not specifically limit as a method to manufacture an ethylene modified polyvinyl alcohol film, The casting film forming method and the melt extrusion film forming method are preferable from a viewpoint of obtaining a favorable ethylene modified polyvinyl alcohol film. Further, the obtained ethylene-modified polyvinyl alcohol film is subjected to drying and heat treatment as necessary.

  Examples of the solvent for dissolving the ethylene-modified polyvinyl alcohol used in producing the ethylene-modified polyvinyl alcohol film include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, Examples include triethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine, diethylenetriamine, glycerin, water, and the like, and one or more of these can be used. Among these, dimethyl sulfoxide, water, or a mixed solvent of glycerin and water is preferably used.

  The ratio of the ethylene-modified polyvinyl alcohol in the ethylene-modified polyvinyl alcohol solution containing water or the ethylene-modified polyvinyl alcohol used in producing the ethylene-modified polyvinyl alcohol film varies depending on the degree of polymerization of the ethylene-modified polyvinyl alcohol, but is 20 to 20 70 mass% is preferable, 25-60 mass% is more preferable, 30-55 mass% is further more preferable, and 35-50 mass% is the most preferable. When the proportion of the ethylene-modified polyvinyl alcohol exceeds 70% by mass, the viscosity of the ethylene-modified polyvinyl alcohol solution or the ethylene-modified polyvinyl alcohol containing water becomes too high, making filtration and defoaming difficult when preparing the stock solution of the film, It becomes difficult to obtain a film free from foreign matter and defects. Further, when the proportion of the ethylene-modified polyvinyl alcohol is lower than 20% by mass, the viscosity of the ethylene-modified polyvinyl alcohol solution or the ethylene-modified polyvinyl alcohol containing water becomes too low, and it is difficult to produce a PVA film having the desired thickness. become. The ethylene-modified polyvinyl alcohol solution or water-containing ethylene-modified polyvinyl alcohol may contain a plasticizer, a surfactant, a dichroic dye, or the like as necessary.

  When producing an ethylene-modified polyvinyl alcohol film, it is preferable to add a polyhydric alcohol as a plasticizer. Examples of the polyhydric alcohol include ethylene glycol, glycerin, propylene glycol, diethylene glycol, diglycerin, triethylene glycol, tetraethylene glycol, trimethylolpropane, etc., and one or more of these are used. can do. Among these, diglycerin, ethylene glycol, and glycerin are preferably used because of the effect of improving stretchability.

  As addition amount of a polyhydric alcohol, 1-30 mass parts is preferable with respect to 100 mass parts of ethylene modified polyvinyl alcohol, 3-25 mass parts is more preferable, and 5-20 mass parts is the most preferable. When the amount is less than 1 part by mass, the dyeability and stretchability may be lowered. When the amount is more than 30 parts by mass, the ethylene-modified polyvinyl alcohol film becomes too flexible and the handleability may be lowered.

  When producing an ethylene-modified polyvinyl alcohol film, it is preferable to add a surfactant. The type of the surfactant is not particularly limited, but an anionic or nonionic surfactant is preferable. As an anionic surfactant, for example, a carboxylic acid type such as potassium laurate, a sulfate ester type such as octyl sulfate, and a sulfonic acid type anionic surfactant such as dodecylbenzene sulfonate are preferable. Nonionic surfactants include, for example, alkyl ether types such as polyoxyethylene oleyl ether, alkylphenyl ether types such as polyoxyethylene octylphenyl ether, alkyl ester types such as polyoxyethylene laurate, and polyoxyethylene laurylamino. Alkylamine type such as ether, alkylamide type such as polyoxyethylene lauric acid amide, polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether, alkanolamide type such as oleic acid diethanolamide, polyoxyalkylene allyl phenyl ether, etc. Nonionic surfactants such as allyl phenyl ether type are preferred. These surfactants can be used alone or in combination of two or more.

  As addition amount of surfactant, 0.01-1 mass part is preferable with respect to 100 mass parts of ethylene modified polyvinyl alcohol, and 0.02-0.5 mass part is more preferable. When the amount is less than 0.01 parts by mass, the effect of improving the film-forming property and peelability is hardly exhibited, and when the amount is more than 1 part by mass, the surfactant is eluted on the surface of the ethylene-modified polyvinyl alcohol film and causes blocking. The handleability may be reduced.

  The ethylene-modified polyvinyl alcohol film used for the production of the polarizer preferably has a thickness of 10 to 50 μm, and more preferably 20 to 40 μm. If the thickness is less than 10 μm, the film strength is too low to perform uniform stretching, and color spots of the polarizer are likely to occur. When the thickness exceeds 50 μm, when a polarizer is produced by uniaxially stretching an ethylene-modified polyvinyl alcohol film, a thickness change due to neck-in at the end tends to occur, and color spots of the polarizer are easily emphasized, which is not preferable. .

  In order to produce a polarizer from an ethylene-modified polyvinyl alcohol film, for example, the ethylene-modified polyvinyl alcohol film may be dyed, uniaxially stretched, fixed, and dried, and further subjected to heat treatment as necessary. There is no restriction | limiting in particular in the order of operation of extending | stretching and a fixing process. Moreover, you may perform uniaxial stretching twice or more.

  Dyeing can be performed before uniaxial stretching, during uniaxial stretching, or after uniaxial stretching. As a dye used for dyeing, iodine-potassium iodide, a dichroic dye, or the like can be used in one kind or a mixture of two or more kinds. The normal dyeing is generally performed by immersing the PVA film in a solution containing the above dye, but the processing conditions and processing method are particularly limited, such as mixing with the PVA film to form a film. is not.

  For uniaxial stretching, wet stretching or dry heat stretching can be used, using warm water such as an aqueous boric acid solution (in a solution containing the dye or in a fixing treatment bath described later) or an ethylene-modified polyvinyl alcohol film after water absorption. Can be done in the air. The stretching temperature is not particularly limited, and is preferably 30 to 90 ° C. when the ethylene-modified polyvinyl alcohol film is stretched (wet stretching) in warm water, and 50 to 180 ° C. is preferable when it is dry-heat stretched. Further, the stretching ratio of uniaxial stretching (the total stretching ratio in the case of multi-stage uniaxial stretching) is preferably 4 times or more, and most preferably 5 times or more from the viewpoint of the polarization performance of the polarizer. The upper limit of the stretching ratio is not particularly limited, but it is preferably 8 times or less because uniform stretching is easily obtained. 2-20 micrometers is preferable and, as for the thickness of the film after extending | stretching, 5-15 micrometers is more preferable.

  Fixing treatment is often performed for the purpose of strengthening the adsorption of the dye to the ethylene-modified polyvinyl alcohol film. Boric acid and / or boron compounds are usually added to the treatment bath used for the fixing treatment. Moreover, you may add an iodine compound in a processing bath as needed.

  It is preferable to perform the drying process of the obtained polarizer at 30-150 degreeC, and it is more preferable to carry out at 50-150 degreeC.

  The polarizer obtained as described above is usually used as a polarizing plate with a polarizing plate protective film bonded to both sides or one side. Examples of the adhesive used for pasting include a PVA-based adhesive and a urethane-based adhesive. Among them, a PVA-based adhesive is preferably used.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” in the examples represents “mass%”.

  The average refractive index at 550 nm of the transparent protective film and the retardation film was measured using an Abbe refractometer 1T (manufactured by Atago Co., Ltd.) and a spectral light source device. Moreover, the thickness of the film was measured using a commercially available micrometer.

  The refractive index nx, ny, and nz at 550 nm of the transparent protective film and the retardation film are measured using the above-described average refractive index with an automatic birefringence measuring device (manufactured by Oji Scientific Instruments, automatic birefringence meter KOBRA21ADH). The inner phase difference Re and the thickness direction phase difference Rth were calculated. The measurement was performed at 23 ° C. and 55 RH%.

  Moreover, the measured refractive index was input into the following formula, and the value of Nz was obtained.

Nz = (nx-nz) / (nx-ny)
(In the formula, the refractive index in the slow axis direction in the plane is nx, the refractive index in the direction perpendicular to the slow axis in the plane is ny, the refractive index in the thickness direction of the film is nz, and d is the thickness of the film ( nm))
Moreover, the phase difference value when no voltage was applied at 550 nm of the liquid crystal cell was measured by the Senarmon method.

Example 1
[Preparation of transparent protective film (R)]
<Dope composition>
Triacetylcellulose (acetylation degree 61.0%) 100 parts by mass 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole
1 part by weight Triphenyl phosphate 15 parts by weight Methylene chloride 475 parts by weight Ethanol 50 parts by weight A dope solution having the above composition was prepared by a well-known method, filtered, and then supported at a dope temperature of 35 ° C. using a belt casting apparatus. Cast evenly on top. At that time, the film was cast on a support so that the dry film thickness was 80 μm.

  After casting, the film was dried at 80 ° C. for 3 minutes, peeled, and further dried at 120 ° C. for 10 minutes. Both ends of the obtained film were subjected to a knurling process having a width of 10 mm and a height of 5 μm to prepare a triacetylcellulose film sample having a film thickness of 80 μm. The film width was 1300 mm and the winding length was 2000 m. This film had an in-plane retardation Re of 2 nm and a thickness direction retardation Rth of 50 nm.

[Preparation of transparent protective film (A1) with small retardation in thickness direction]
<Dope composition>
Triacetylcellulose (acetylation degree 61.5%) 85 parts by mass 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole
2 parts by mass Methyl methacrylate-hydroxyethyl acrylate copolymer (80/20 (mass ratio), Mw; 8000) 10 parts by mass Methyl acrylate polymer (*) 5 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass (*) A methyl acrylate monomer was polymerized by the polymerization method described in Example 3 of JP-A No. 2000-128911 to obtain Mw1000 and Mn700 polymers. The reaction product had a hydroxyl value (OHV; mg / g KOH) of 50.

  The dope composition was put into a sealed container, heated to 70 ° C., and while stirring, cellulose triacetate (TAC) was completely dissolved to obtain a dope. The time required for dissolution was 4 hours. After the dope composition was filtered, it was uniformly cast on a stainless band support having a dope temperature of 35 ° C. and a temperature of 22 ° C. using a belt casting apparatus. The temperature of the stainless steel band support was 20 ° C.

  Then, after making it dry to the range which can be peeled, dope was peeled from the stainless steel band support body. At this time, the residual solvent amount of the dope was 25%. The time required from casting the dope to peeling was 3 minutes. After peeling from the stainless steel band support, after drying at 120 ° C while holding in the width direction, release the width holding and finish drying at 120 ° C and 135 ° C drying zones while transporting with many rolls. A cellulose triacetate film sample having a film thickness of 80 μm was prepared by applying a knurling process having a width of 10 mm and a height of 5 μm to both ends of the film. The film width was 1300 mm and the winding length was 3000 m. The winding tension was an initial tension of 150 N / 1300 mm and a final winding tension of 100 N / 1300 mm. The obtained triacetylcellulose film had a thickness of 80 μm, an in-plane retardation Re of 0 nm, and a thickness direction retardation Rth of 0 nm.

[Preparation of transparent protective film (A2) having small thickness direction retardation]
A triacetyl cellulose film was produced in the same manner as the production method of the transparent protective film (A1) except that the dope composition was changed to the following composition. The obtained triacetylcellulose film had a thickness of 80 μm, an in-plane retardation Re of 1 nm, and a thickness direction retardation Rth of 5 nm.

<Dope composition>
Triacetylcellulose (acetylation degree 61.0%) 85 parts by mass 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole
2 parts by weight Vinyl acetate polymer (*) 15 parts by weight Methylene chloride 475 parts by weight Ethanol 50 parts by weight (*) A vinyl acetate monomer was synthesized by the polymerization method described in Example 3 of JP-A No. 2000-128911, and Mw 4500 and Mn 3500. Of polymer was obtained. The hydroxyl value (OHV; mg / g KOH) of this reaction product was 20.

[Preparation of transparent protective film (A3) with small retardation in thickness direction]
A triacetyl cellulose film was produced in the same manner as the production method of the transparent protective film (A1) except that the dope composition was changed to the following composition. The obtained triacetylcellulose film had a thickness of 80 μm, an in-plane retardation Re of 1 nm, and a thickness direction retardation Rth of 10 nm.

<Dope composition>
Triacetylcellulose (acetylation degree 61.0%) 85 parts by mass 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole
2 parts by weight Vinyl acetate polymer (*) 10 parts by weight Methylene chloride 475 parts by weight Ethanol 50 parts by weight (*) A vinyl acetate monomer was synthesized by the polymerization method described in Example 3 of JP-A No. 2000-128911, and Mw 4500 and Mn 3500. Of polymer was obtained. The hydroxyl value (OHV; mg / g KOH) of this reaction product was 20.

[Production of Transparent Protective Film (A4) with Small Thickness Direction Difference]
A triacetyl cellulose film was produced in the same manner as the production method of the transparent protective film (A1) except that the dope composition was changed to the following composition. The obtained triacetylcellulose film had a thickness of 80 μm, an in-plane retardation Re of 1 nm, and a thickness direction retardation Rth of 20 nm.

<Dope composition>
Triacetyl cellulose (acetylation degree 61.0%) 95 parts by weight Methyl acrylate polymer (*) 5 parts by weight Methylene chloride 475 parts by weight Ethanol 50 parts by weight (*) Polymerization described in Example 3 of JP-A No. 2000-128911 The methyl acrylate monomer was polymerized by the method to obtain polymers with Mw 1000 and Mn 700. The hydroxyl value (OHV; mg / g KOH) of this reaction product was 50.

[Preparation of transparent protective film (A5) with small retardation in thickness direction]
A triacetyl cellulose film was produced in the same manner as the production method of the transparent protective film (A1) except that the dope composition was changed to the following composition. The obtained triacetylcellulose film had a thickness of 80 μm, an in-plane retardation Re of 1 nm, and a thickness direction retardation Rth of −20 nm.

<Dope composition>
Triacetyl cellulose (acetylation degree 61.5%) 70 parts by weight Methyl acrylate polymer (*) 30 parts by weight Methylene chloride 475 parts by weight Ethanol 50 parts by weight (*) Polymerization described in Example 3 of JP-A No. 2000-128911 The methyl acrylate monomer was polymerized by the method to obtain polymers with Mw 1000 and Mn 700. The hydroxyl value (OHV; mg / g KOH) of this reaction product was 50.

[Preparation of transparent protective film (A6) with small retardation in thickness direction]
A triacetylcellulose film was produced in the same manner as the production method of the transparent protective film (A1), except that the same dope composition as in the production method of the transparent protective film (A1) was used and the film thickness was changed to 40 μm. The obtained triacetylcellulose film had a thickness of 40 μm, an in-plane retardation Re of 0 nm, and a thickness direction retardation Rth of 0 nm.

[Preparation of Retardation Film (3)] A polycarbonate film was stretched using a heat-shrinkable film to obtain a retardation film (3) having a thickness of 60 μm. At this time, the stretching ratio and the shrinkage amount of the heat-shrinkable film were adjusted so that the in-plane retardations Re ₃ and Nz ₃ as shown in Table 1 were obtained.

[Preparation of retardation film (4)]
A thermoplastic saturated norbornene resin (manufactured by Nippon Zeon Co., Ltd., ZEONOR1600R) was supplied to a single screw extruder, extruded at 275-290 ° C., and stretched to obtain a retardation film (4) having a thickness of 80 μm. At this time, the draw ratio was adjusted so that the in-plane retardations Re ₄ and Nz ₄ as shown in Table 2 were produced. [Production of Polarizing Plate (1) and Polarizing Plate (2)]
The transparent protective film was alkali-treated with a 2.5 mol / L sodium hydroxide aqueous solution at 40 ° C. for 60 seconds and washed with water for 3 minutes to form a saponified layer, whereby an alkali-treated film was obtained.

  Next, a 120 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 g of iodine, 5 g of potassium iodide, and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. consisting of 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. The polarizer P was obtained by drying.

  The transparent protective film subjected to the alkali treatment was laminated thereon using an adhesive to produce a polarizing plate (1) and a polarizing plate (2).

  At this time, the transparent protective films bonded to both surfaces of the polarizer P of the film stretched by adsorbing iodine to the polyvinyl alcohol film were combined as shown in Table 1.

[Production of Optical Film (1) and Optical Film (2)]
The polarizing plate (1) and the retardation film (3) were laminated using an adhesive to produce an optical film (1).

At this time, combinations of the transparent protective film of the polarizing plate (1) and the in-plane retardations Re ₃ and Nz ₃ of the retardation film (3) were set as shown in Table 1.

  Similarly, it laminated | stacked using the said polarizing plate (2) and the said phase difference film (4) adhesive, and produced the optical film (2).

At this time, combinations of the transparent protective film of the polarizing plate (2) and the in-plane retardations Re ₄ and Nz ₄ of the retardation film (4) were as shown in Table 2.

[Production of liquid crystal display device]
Using an IPS mode liquid crystal cell having a retardation value at 550 nm of 280 nm, the optical film (1) and the optical film (2) were laminated with an adhesive.

  At this time, combinations of the optical film (1) and the optical film (2) were as shown in Tables 1 and 2.

  The absorption axes of the polarizers of the polarizing plates (1) and (2), the slow axes of the retardation films (3) and (4), and the extraordinary refractive index direction of the liquid crystal in the liquid crystal cell are shown in FIG. The direction of pasting was adjusted so that

  That is, in the optical film (1), the absorption axis of the polarizer of the polarizing plate (1) and the slow axis of the retardation film (3) were made parallel. In the optical film (2), the absorption axis of the polarizer of the polarizing plate (2) and the slow axis of the retardation film (4) were made parallel.

  Further, the absorption axes of the polarizing plate (1) and the polarizing plate (2) were orthogonal to each other so that the incident-side polarizing plate (2) and the extraordinary refractive index direction of the liquid crystal in the liquid crystal cell were parallel.

  As described above, IPS mode liquid crystal display devices 1 to 25 were produced.

[Evaluation]
The liquid crystal display devices 1 to 25 produced above were placed on a backlight, and the contrast ratio in the direction of 70 degrees tilted from the normal direction was measured at an azimuth direction of 45 degrees with respect to the optical axis of the orthogonal polarizing plate. The contrast ratio was measured using EZ Contrast (ELDIM).

  From the above table, the liquid crystal display devices 2 to 11, 14, 15, 18, 19, 22, and 23 of the present invention have a higher contrast ratio than the comparative examples and are excellent in displaying images from an oblique direction. I understood that.

Example 2
The optical film on the viewing side of the liquid crystal cell of the liquid crystal panel of Toshiba Corporation liquid crystal television FACE 23LC100 was peeled off. Since this optical film had a polarizing plate and a retardation film attached to each other, the retardation film was peeled off to make only a polarizing plate. The transparent protective film on the liquid crystal cell side of the polarizing plate is peeled off, and the transparent protective film (A1) having a small retardation in the thickness direction is attached instead, and the retardation film peeled off first is attached as it is. In addition, an optical film was obtained. This optical film was pasted on the liquid crystal cell as it was and the contrast ratio in the direction of 70 degrees tilted from the normal direction was measured at an angle of 45 degrees (in the direction of 1:30 on the watch). The contrast ratio was measured using EZ Contrast (ELDIM).

  Next, the optical film on the backlight side of the liquid crystal cell of the liquid crystal panel of the liquid crystal television was peeled off. Since this optical film had a polarizing plate and a phase difference retardation film attached to each other, the phase difference film was peeled off to make only a polarizing plate. The transparent protective film on the liquid crystal cell side of the polarizing plate is peeled off, and the transparent protective film (A1) having a small retardation in the thickness direction is attached instead, and the retardation film peeled off first is attached as it was. In addition, an optical film was obtained. This optical film was pasted on the liquid crystal cell as it was and the contrast ratio in the direction of 70 degrees tilted from the normal direction was measured at an angle of 45 degrees (in the direction of 1:30 on the watch).

  Further, the optical films on the viewing side and the backlight side of the liquid crystal cell of the liquid crystal panel of the liquid crystal television were peeled off. Since these optical films had a polarizing plate and a retardation retardation film attached to each other, these retardation films were peeled off to make only a polarizing plate. The transparent protective film on the liquid crystal cell side of these polarizing plates is peeled off, and the transparent protective film (A1) having a small retardation in the thickness direction is attached instead, and the retardation film peeled off first is restored as it was. Bonding was made into an optical film. This optical film was pasted on the liquid crystal cell as it was and the contrast ratio in the direction of 70 degrees tilted from the normal direction was measured at an angle of 45 degrees (in the direction of 1:30 on the watch).

  As a comparative example, when the liquid crystal television was left as it was, the contrast ratio in the direction of 70 degrees tilted from the normal direction was measured at an angle of 45 degrees (in the direction of 1:30 on the watch). It was found that the viewing angle was greatly improved.

Example 3
An IPS mode liquid crystal display device was produced in the same manner as in Example 1 except that the following polarizer Q was used instead of the polarizer P used in Example 1, and the same evaluation as in Example 1 was performed. It has been found that the liquid crystal display device having the configuration of the present invention can provide a transmissive liquid crystal display device that exhibits high contrast and can display an excellent image even in an oblique direction. In addition, no light leakage was observed even after long-term use.

<Polarizer Q: Ethylene-modified PVA film>
100 parts by mass of ethylene-modified PVA having an ethylene unit content of 2.1 mol%, a saponification degree of 99.92 mol% and a polymerization degree of 3000 is impregnated with 10 parts by mass of glycerin and 200 parts by mass of water. After foaming, it was melt-extruded from a T die to a metal roll to form a film. The ethylene-modified PVA film obtained after drying and heat treatment had a thickness of 40 μm, and the average hot water cutting temperature of the film was 70 ° C.

  The ethylene-modified PVA film thus obtained was successively treated in the order of pre-swelling, dyeing, uniaxial stretching, fixing treatment, drying and heat treatment to produce a polarizing film. That is, the ethylene-modified PVA film is pre-swelled by immersing it in water at 30 ° C. for 60 seconds, and is immersed in a 35 ° C. aqueous solution having a boric acid concentration of 40 g / liter, an iodine concentration of 0.4 g / liter, and a potassium iodide concentration of 60 g / liter. Soaked for 2 minutes. Subsequently, it was uniaxially stretched 6 times in an aqueous solution at 55 ° C. with a boric acid concentration of 4%, and in an aqueous solution at 30 ° C. with a potassium iodide concentration of 60 g / liter, a boric acid concentration of 40 g / liter, and a zinc chloride concentration of 10 g / liter. For 5 minutes, and fixed. Thereafter, the ethylene-modified PVA film was taken out, dried with hot air at 40 ° C. under a constant length, and further subjected to heat treatment at 100 ° C. for 5 minutes. The obtained polarizing film had an average thickness of 13 μm, and the polarizing performance was a transmittance of 43.0%, a polarization degree of 99.5%, and a dichroic ratio of 40.1.

Example 4
The liquid crystal display device manufactured in Example 1 is installed on a backlight, and the azimuth angle (azimuth angle) with respect to the optical axis of the orthogonal polarizing plate at an inclination of 70 degrees from the normal direction is 0 to 360 degrees. The change in color was measured using EZ Contrast (ELDIM). At this time, the liquid crystal display device displayed black.

  When the result of this measurement was plotted on the xy chromaticity diagram, the liquid crystal display device 1 varied greatly from x, y = 0.21, 0.18 to 0.38, 0.37, and the change in color was large. On the other hand, in the liquid crystal display device 4, fluctuations in x, y = 0.22, 0.20 to 0.31, and 0.35 are suppressed, and it can be seen that there is little change in color. Similarly, when the measurement was performed with the liquid crystal display device 2, x, y = 0.21, 0.19 to 0.35, and 0.36 were varied.

  In the liquid crystal display device 3, x, y = 0.21, 0.20 to 0.36, and 0.36 were changed.

  Therefore, when a film having a small in-plane retardation Re and a thickness direction retardation Rth is used for the transparent protective films (1-2) and (2-1) of the polarizing plate, the color changes depending on the direction in which the liquid crystal display device is viewed. I understand that there are few.

Claims (11)

A polarizing plate (1) and a polarizing plate (2) each having a transparent protective film laminated on both sides of a polarizer are arranged on both sides of a liquid crystal cell driven in an IPS mode composed of a pair of substrates sandwiching a liquid crystal layer. The following retardation film (3) is disposed between the liquid crystal cell and the polarizing plate (1), and the following retardation film (4) is disposed between the liquid crystal cell and the polarizing plate (2). In a transmissive liquid crystal display device,
The transparent protective film (1-2) on the liquid crystal cell side of the polarizing plate (1) and the transparent protective film (2-1) on the liquid crystal cell side of the polarizing plate (2) are the following (A). A transmissive liquid crystal display device comprising:
(A): The direction in which the in-plane refractive index is maximum is the X-axis, the direction perpendicular to the X-axis is the Y-axis, the thickness direction of the film is the Z-axis, and the refractive index in each axial direction is nx, ny, nz When the film thickness is d (nm), the in-plane retardation Re = (nx−ny) × d is 0 to 5 nm, and the thickness direction retardation Rth = {(nx + ny) / 2−nz. } × d is −20 to 20 nm. Retardation film (3): The direction in which the in-plane refractive index is the maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis. _{nx 3, ny 3, nz 3} , the thickness of the film when d ₃ and (nm), nz ₃ value represented by _{nz 3 = (nx 3 -nz 3} ) / (nx 3 -ny 3) is 0 to 0.35 is satisfied, and the in-plane retardation Re ₃ = (nx ₃ −ny ₃ ) × d ₃ is 60 to 450 nm. Retardation film (4): The direction in which the in-plane refractive index is the maximum is the X-axis, the direction perpendicular to the X-axis is the Y-axis, and the thickness direction of the film is the Z-axis. _{nx 4, ny 4, nz 4} , the thickness of the film when d ₄ and (nm), nz ₄ value represented by _{nz 4 = (nx 4 -nz 4} ) / (nx 4 -ny 4) is 0.8 to 1.2 is satisfied, and the in-plane retardation Re ₄ = (nx ₄ −ny ₄ ) × d ₄ is 60 to 450 nm. A polarizing plate (1) and a polarizing plate (2) each having a transparent protective film laminated on both sides of a polarizer are arranged on both sides of a liquid crystal cell driven in an IPS mode composed of a pair of substrates sandwiching a liquid crystal layer. The retardation film (3) is disposed between the liquid crystal cell and the polarizing plate (1), and the retardation film (4) is disposed between the liquid crystal cell and the polarizing plate (2). In the transmissive liquid crystal display device
The transmissive liquid crystal display device according to claim 1, wherein the transparent protective film (2-1) on the liquid crystal cell side of the polarizing plate (2) is the above (A). A polarizing plate (1) and a polarizing plate (2) each having a transparent protective film laminated on both sides of a polarizer are arranged on both sides of a liquid crystal cell driven in an IPS mode composed of a pair of substrates sandwiching a liquid crystal layer. The retardation film (3) is disposed between the liquid crystal cell and the polarizing plate (1), and the retardation film (4) is disposed between the liquid crystal cell and the polarizing plate (2). In the transmissive liquid crystal display device
The transparent protective film (1-2) on the liquid crystal cell side of the polarizing plate (1) and the transparent protective film (2-1) on the liquid crystal cell side of the polarizing plate (2) are both (A). The transmissive liquid crystal display device according to claim 1, wherein: The transmissive liquid crystal display device according to any one of claims 1 to 3, wherein the transparent protective film (A) is a cellulose ester film. The transmissive liquid crystal display device according to claim 4, wherein the cellulose ester film (A) has a thickness of 30 to 60 µm. The cellulose ester film of (A) contains a polymer obtained by polymerizing a compound having a weight average molecular weight of 500 to 30,000 and having an ethylenic double bond. 6. A transmissive liquid crystal display device according to item 5. The transmissive liquid crystal display device according to any one of claims 1 to 6, wherein the polarizer uses ethylene-modified polyvinyl alcohol. 8. The liquid crystal cell driven in the IPS mode has a phase difference value at 550 nm of 230 to 360 nm when no voltage is applied, 8. Transmissive liquid crystal display device. An optical film in which the polarizing plate (1) and the retardation film (3) are laminated so that the absorption axis of the polarizing plate (1) and the slow axis of the retardation film (3) are orthogonal or parallel to each other. The polarizing plate (2) and the retardation film (4) were laminated so that the absorption axis of the polarizing plate (2) and the slow axis of the retardation film (4) were orthogonal or parallel to each other. An optical film (2) is used, and the optical film (1) and the optical film (2) are combined with the liquid crystal so that the absorption axes of the polarizing plate (1) and the polarizing plate (2) are orthogonal to each other. The transmissive liquid crystal display device according to any one of claims 1 to 8, wherein the transmissive liquid crystal display device is disposed on each side of the cell. The optical film (1) is disposed on the cell substrate on the viewing side, and the optical film (2) is disposed on the cell substrate on the incident side. The abnormal light of the liquid crystal substance in the liquid crystal cell when no voltage is applied. The transmissive liquid crystal display device according to claim 9, wherein the refractive index direction and the absorption axis of the polarizing plate on the incident side are in a parallel state. The optical film (1) is laminated so that the absorption axis of the polarizing plate (1) and the slow axis of the retardation film (3) are parallel, and the optical film (2) is a polarizing plate ( 10. The transmission type liquid crystal display device according to claim 9, wherein the absorption axis of 2) and the retardation film (4) are laminated so as to be parallel to each other.