JP4969412B2 - Optical film, liquid crystal panel, and liquid crystal display device - Google Patents

Description

  The present invention relates to an optical film, a liquid crystal panel, and a liquid crystal display device. More specifically, the present invention relates to an optical film suitable for a liquid crystal display device capable of obtaining a neutral display having no color in all directions, a liquid crystal panel using the optical film, and a liquid crystal display device using the liquid crystal panel.

  FIG. 5A is a schematic cross-sectional view of a conventional typical liquid crystal display device, and FIG. 5B is a schematic cross-sectional view of a liquid crystal cell used in the liquid crystal display device. The liquid crystal display device 900 includes a liquid crystal cell 910, retardation plates 920 and 920 ′ disposed outside the liquid crystal cell 910, and polarizing plates 930 and 930 ′ disposed outside the retardation plates 920 and 920 ′. Is provided. Typically, the polarizing plates 930 and 930 'are arranged so that their polarization axes are orthogonal to each other. The liquid crystal cell 910 includes a pair of substrates 911 and 911 ′ and a liquid crystal layer 912 as a display medium disposed between the substrates. One substrate 911 is provided with a switching element (typically a TFT) for controlling the electro-optical characteristics of the liquid crystal, a scanning line for supplying a gate signal to the active element, and a signal line for supplying a source signal ( Neither is shown). The other substrate 911 'is provided with color layers 913R, 913G, 913B and a light shielding layer (black matrix layer) 914 constituting a color filter. A distance (cell gap) between the substrates 911 and 911 ′ is controlled by a spacer (not shown).

  The retardation plate is used for the purpose of optical compensation of a liquid crystal display device. In order to obtain optimum optical compensation (for example, improvement of viewing angle characteristics, improvement of color shift, improvement of contrast), various attempts have been made regarding optimization of optical characteristics of retardation plates and / or arrangement in liquid crystal display devices. Has been made. Conventionally, as shown in FIG. 5 described above, one retardation plate is disposed between the liquid crystal cell 910 and the polarizing plates 930 and 930 ′ (see, for example, Patent Document 1).

  With the recent increase in definition and functionality of liquid crystal display devices, further improvements in screen uniformity and display quality are required. However, in a conventional liquid crystal display device, it has been difficult to develop a neutral display with no color in all directions.

Furthermore, with the miniaturization and portability of liquid crystal display devices, the demand for thinning is also increasing. One means for reducing the thickness is to cause the retardation plate to also serve as a polarizer protective film, and directly attach the retardation plate to the polarizer (see, for example, Patent Document 2). However, when the retardation plate is directly attached to the polarizer, there is a problem that a nick defect (sometimes simply referred to as a nick) that is a local unevenness defect occurs at the interface between the retardation plate and the polarizer. . When a nick defect occurs, optical performance such as display unevenness is reduced in the liquid crystal display device.
JP-A-11-95208 Japanese Patent No. 3807511

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is an optical film that can provide a liquid crystal display device that provides neutral display with no color in all directions and high contrast. An object of the present invention is to provide an optical film in which knick defects are suppressed, a liquid crystal panel using the optical film, and a liquid crystal display device using the liquid crystal panel.

  The present inventor has intensively studied to solve the above problems. As a result, attention was paid to the laminated structure of the optical film and the adhesive used for the lamination. Then, as an optical film, a configuration in which a birefringent layer made of a cyclic olefin film having an Nz coefficient within a specific range is arranged on one side of the polarizer, and the polarizer and the birefringent layer are arranged. As a result, the present invention has been completed.

  The optical film of the present invention is a composite film comprising a transparent protective film, a polarizer, and a cyclic olefin-based film in which the Nz coefficient defined by Nz = (nx−nz) / (nx−ny) has a relationship of 1 <Nz ≦ 2. A refractive layer is included in this order, and the polarizer and the birefringent layer are directly laminated via a polyvinyl alcohol-based adhesive containing a metal compound colloid.

  In a preferred embodiment, the transparent protective film is either a cellulose film or an acrylic film.

  In a preferred embodiment, the absorption axis of the polarizer and the slow axis of the birefringent layer are substantially orthogonal.

  In a preferred embodiment, the birefringent layer is a λ / 4 plate.

  According to another aspect of the present invention, a liquid crystal panel is provided. The liquid crystal panel of the present invention includes a liquid crystal cell and the optical film of the present invention disposed on the viewing side of the liquid crystal cell.

  In a preferred embodiment, a birefringent layer having a relationship of nx = ny> nz is disposed on the backlight side of the liquid crystal cell.

  In a preferred embodiment, the birefringent layer having the relationship of nx = ny> nz includes at least one non-liquid crystal material selected from polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide.

  In a preferred embodiment, the liquid crystal cell is in a VA mode or an OCB mode.

  According to another aspect of the present invention, a liquid crystal display device is provided. The liquid crystal display device of the present invention includes the liquid crystal panel of the present invention.

  According to the present invention, an optical film that can provide a liquid crystal display device that provides neutral display with no color in all directions and high contrast, an optical film that suppresses nick defects, a liquid crystal panel using the optical film, and the A liquid crystal display device using a liquid crystal panel can be provided.

  Such effects include birefringence comprising a transparent protective film, a polarizer, and a cyclic olefin-based film in which the Nz coefficient defined by Nz = (nx−nz) / (nx−ny) is 1 <Nz ≦ 2. It can be remarkably expressed by an optical film comprising layers in this order, wherein the polarizer and the birefringent layer are laminated directly via a polyvinyl alcohol-based adhesive containing a metal compound colloid.

(Definition of terms and symbols)
The definitions of terms and symbols in this specification are as follows.

  (1) “nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction perpendicular to the slow axis in the plane (ie, fast phase). (Nz direction), and “nz” is the refractive index in the thickness direction. For example, “nx = ny” includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. In the present specification, “substantially equal” is intended to encompass the case where nx and ny are different within a range that does not practically affect the overall polarization characteristics of the optical film.

  (2) “In-plane retardation Δnd” refers to a retardation value in a film (layer) plane measured with light having a wavelength of 590 nm at 23 ° C. Δnd is a formula when the refractive index in the slow axis direction and the fast axis direction of the film (layer) at a wavelength of 590 nm is nx and ny, respectively, and d (nm) is the thickness of the film (layer): Δnd = It is calculated by (nx−ny) × d.

  (3) Thickness direction retardation Rth refers to a thickness direction retardation value measured at 23 ° C. with light having a wavelength of 590 nm. Rth is the formula: Rth = (nx) where the refractive index in the slow axis direction and the thickness direction of the film (layer) at a wavelength of 590 nm is nx and nz, and d (nm) is the thickness of the film (layer). -Nz) * d.

A. Configuration of Liquid Crystal Panel and Liquid Crystal Display Device Including the Same FIG. 1 is a schematic sectional view for explaining a preferred example of the liquid crystal panel of the present invention. The liquid crystal panel 100 includes a first transparent protective film 10, a first polarizer 30, a first birefringent layer 60, a liquid crystal cell 40, a second birefringent layer 70, a second transparent protective film 11, and a second. The polarizer 50 and the third transparent protective film 12 are provided in this order. The first transparent protective film, the first polarizer, and the first birefringent layer may be arranged on the viewing side or the backlight side of the liquid crystal cell, but are preferably on the viewing side. It is arranged in.

  The first birefringent layer 60 is a birefringent layer made of a cyclic olefin-based film in which the Nz coefficient defined by Nz = (nx−nz) / (nx−ny) has a relationship of 1 <Nz ≦ 2. The second birefringent layer 70 is preferably a birefringent layer having a relationship of nx = ny> nz. Details of the first birefringent layer 60 and the second birefringent layer 70 will be described later.

  In FIG. 1, the laminated body of the 1st transparent protective film 10, the 1st polarizer 30, and the 1st birefringent layer 60 is a preferable example of the optical film of this invention. In the optical film of the present invention, the first polarizer 30 and the first birefringent layer 60 are not disposed with a transparent protective film therebetween, and a polyvinyl alcohol adhesive containing a metal oxide colloid. It is laminated directly through. Thereby, it can be set as an optical film suitable for the liquid crystal display device from which a neutral display without a color is obtained in all directions.

The absorption axis of the first polarizer 30 and the slow axis of the first birefringent layer 60 are substantially orthogonal.

  The liquid crystal cell 40 has a pair of glass substrates 41 and 42 and a liquid crystal layer 43 as a display medium disposed between the substrates. One substrate (active matrix substrate) 41 includes a switching element (typically a TFT) for controlling the electro-optical characteristics of the liquid crystal, a scanning line for supplying a gate signal to the switching element, and a signal line for supplying a source signal. Provided (none shown). The other glass substrate (color filter substrate) 42 is provided with a color filter (not shown). The color filter may be provided on the active matrix substrate 41. A distance (cell gap) between the substrates 41 and 42 is controlled by a spacer 44. An alignment film (not shown) made of polyimide, for example, is provided on the side of the substrates 41 and 42 in contact with the liquid crystal layer 43.

  As a driving mode of the liquid crystal cell 40, any appropriate driving mode can be adopted as long as the effect of the present invention can be obtained. Specific examples of the drive mode include STN (Super Twisted Nematic) mode, TN (Twisted Nematic) mode, IPS (In-Plane Switching) mode, VA (Vertical Aligned Hidden Alignment mode), OCB (Optically Aligned Hiely mode) Examples include an aligned nematic (ASM) mode and an ASM (axially aligned microcell) mode. VA mode and OCB mode are preferred. This is because the color shift is remarkably improved.

  FIG. 2 is a schematic cross-sectional view illustrating the alignment state of liquid crystal molecules in the VA mode. As shown in FIG. 2A, the liquid crystal molecules are aligned perpendicular to the surfaces of the substrates 41 and 42 when no voltage is applied. Such vertical alignment can be realized by arranging a nematic liquid crystal having negative dielectric anisotropy between substrates on which a vertical alignment film (not shown) is formed. When light is incident from the surface of one substrate 41 in such a state, the linearly polarized light that has passed through the second polarizer 50 and entered the liquid crystal layer 43 is the major axis of the vertically aligned liquid crystal molecules. Proceed along the direction of Since no birefringence occurs in the major axis direction of the liquid crystal molecules, the incident light travels without changing the polarization direction and is absorbed by the first polarizer 30 having a polarization axis orthogonal to the second polarizer 50. This provides a dark display when no voltage is applied (normally black mode). As shown in FIG. 2B, when a voltage is applied between the electrodes, the major axis of the liquid crystal molecules is aligned parallel to the substrate surface. Liquid crystal molecules exhibit birefringence with respect to linearly polarized light incident on the liquid crystal layer 43 in this state, and the polarization state of incident light changes according to the inclination of the liquid crystal molecules. Light that passes through the liquid crystal layer when a predetermined maximum voltage is applied becomes, for example, linearly polarized light whose polarization direction is rotated by 90 °, and thus the light is transmitted through the first polarizer 30 to obtain a bright display. When the voltage is not applied again, the display can be returned to the dark state by the orientation regulating force. Further, gradation display is possible by changing the applied voltage to control the tilt of the liquid crystal molecules to change the transmitted light intensity from the first polarizer 30.

  FIG. 3 is a schematic cross-sectional view illustrating the alignment state of liquid crystal molecules in the OCB mode. The OCB mode is a driving mode in which the liquid crystal layer 43 is configured by so-called bend alignment. As shown in FIG. 3C, the bend alignment has a substantially parallel angle (alignment angle) when the alignment of nematic liquid crystal molecules is in the vicinity of the substrate, and the alignment plane increases toward the center of the liquid crystal layer. An alignment state that exhibits an angle perpendicular to the liquid crystal layer, gradually changes so as to be aligned with the opposing substrate surface as the distance from the center of the liquid crystal layer, and does not have a twisted structure throughout the liquid crystal layer. Such a bend orientation is formed as follows. As shown in FIG. 3A, in a state where no electric field or the like is applied (initial state), the liquid crystal molecules are substantially homogeneously aligned. However, the liquid crystal molecules have a pretilt angle, and the pretilt angle near the substrate is different from the pretilt angle near the opposite substrate. When a predetermined bias voltage (typically 1.5 V to 1.9 V) is applied here (when a low voltage is applied), a splay orientation as shown in FIG. A transition to bend orientation as shown can be achieved. When a display voltage (typically 5 V to 7 V) is applied from the bend alignment state (when a high voltage is applied), the liquid crystal molecules rise substantially perpendicular to the substrate surface as shown in FIG. In the normally white display mode, light that passes through the second polarizer 50 and enters the liquid crystal layer in the state of FIG. 3D when a high voltage is applied proceeds without changing the polarization direction. It is absorbed by one polarizer 30. Therefore, a dark state is displayed. When the display voltage is lowered, it can return to the bend alignment and return to the bright display by the alignment regulating force of the rubbing process. In addition, gradation display is possible by changing the display voltage to control the tilt of the liquid crystal molecules to change the transmitted light intensity from the polarizer. Note that a liquid crystal display device including an OCB mode liquid crystal cell can switch the phase transition from the splay alignment state to the bend alignment state at a very high speed. In comparison, it has a feature of excellent moving image display characteristics.

  The OCB mode liquid crystal cell display mode can be used in either a normally white mode that takes a dark state (black display) when a high voltage is applied or a normally black mode that takes a bright state (white display) when a high voltage is applied. can do.

  The cell gap of the OCB mode liquid crystal cell is preferably 2 μm to 10 μm, more preferably 3 μm to 9 μm, and particularly preferably 4 μm to 8 μm. Within the above range, the response time can be shortened and good display characteristics can be obtained.

The nematic liquid crystal used in the OCB mode liquid crystal cell preferably has a positive dielectric anisotropy. Specific examples of nematic liquid crystals having positive dielectric anisotropy include those described in JP-A-9-176645. A commercially available nematic liquid crystal may be used as it is. Examples of the commercially available nematic liquid crystal include a product name “ZLI-4535” and a product name “ZLI-1132” manufactured by Merck. The difference between the ordinary refractive index (no) and the extraordinary refractive index (ne) of the nematic liquid crystal, that is, the birefringence (Δn _LC ) is appropriately selected depending on the response speed, transmittance, etc. of the liquid crystal. Is 0.05-0.30, more preferably 0.10-0.30, and still more preferably 0.12-0.30. Further, the pretilt angle of such nematic liquid crystal is preferably 1 ° to 10 °, more preferably 2 ° to 8 °, and particularly preferably 3 ° to 6 °. Within the above range, the response time can be shortened and good display characteristics can be obtained.

  The liquid crystal panel as described above is suitably used for liquid crystal display devices such as personal computers, liquid crystal televisions, mobile phones, personal digital assistants (PDAs), and projectors.

B. Polarizer The polarizer (for example, the 1st polarizer 30 and the 2nd polarizer 50) in the present invention is formed from polyvinyl alcohol system resin. As the polarizer in the present invention, a polyvinyl alcohol resin film dyed with a dichroic substance (typically iodine or a dichroic dye) and uniaxially stretched is preferably used. The polymerization degree of the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film is preferably 100 to 5000, and more preferably 1400 to 4000. The polyvinyl alcohol-based resin film constituting the polarizer can be formed by any suitable method (for example, a casting method in which a solution obtained by dissolving a resin in water or an organic solvent is cast, a casting method, an extrusion method). . The thickness of the polarizer can be appropriately set according to the purpose and application of the liquid crystal display device or image display device used, but is preferably 5 to 80 μm.

  As a method for producing a polarizer, a method in which the polyvinyl alcohol-based resin film is subjected to a production process including a dyeing process, a crosslinking process, a stretching process, a washing process, and a drying process is employed. In each processing step except the drying step, the treatment is performed by immersing the polyvinyl alcohol-based resin film in a bath containing a solution used in each step. The order, number of times, and the presence / absence of each process of the dyeing process, the crosslinking process, the stretching process, the washing process, and the drying process can be appropriately set according to the purpose, materials used, conditions, and the like. For example, several processes may be performed simultaneously in one process, and a specific process may be omitted. More specifically, for example, the stretching process may be performed after the dyeing process, may be performed before the dyeing process, or may be performed simultaneously with the dyeing process and the crosslinking process. Further, for example, it can be suitably employed to perform the crosslinking treatment before and after the stretching treatment. Further, for example, the cleaning process may be performed after all the processes, or may be performed only after a specific process. Particularly preferably, the dyeing step, the crosslinking step, the stretching step, the washing step, and the drying step are performed in this order. Moreover, it is also a preferable aspect to perform a swelling process before a dyeing process.

(Swelling process)
The swelling step is a step of swelling the polyvinyl alcohol-based resin film. Typically, it is performed by immersing the polyvinyl alcohol resin film in a treatment bath (swelling bath) filled with water. By this treatment, dirt on the surface of the polyvinyl alcohol-based resin film and an anti-blocking agent can be washed, and unevenness such as uneven dyeing can be prevented by swelling the polyvinyl alcohol-based resin film. Glycerin, potassium iodide, or the like can be appropriately added to the swelling bath. The temperature of the swelling bath is preferably 20 to 60 ° C., more preferably 20 to 50 ° C., and the immersion time in the swelling bath is preferably 0.1 to 10 minutes, more preferably 1 to 7 minutes. In addition, since a polyvinyl alcohol-type resin film can also be swollen in the dyeing process mentioned later, this swelling process can also be abbreviate | omitted.

  When pulling up the film from the swelling bath, any appropriate liquid break roll such as a pinch roll may be used as necessary to prevent the occurrence of dripping, or the liquid may be removed with an air knife. Excess water may be removed by a method such as scraping off.

(Dyeing process)
The dyeing step is typically performed by immersing the polyvinyl alcohol resin film in a treatment bath (dye bath) containing a dichroic substance such as iodine (sometimes referred to as adsorption or contact). Done. As the solvent used for the dye bath solution, water is generally used, but an appropriate amount of an organic solvent compatible with water may be added. The dichroic substance is used in a proportion of preferably 0.01 to 10 parts by weight, more preferably 0.02 to 7 parts by weight, and still more preferably 0.025 to 5 parts by weight with respect to 100 parts by weight of the solvent. .

  Any appropriate substance suitable for the present invention can be used as the dichroic substance, and examples thereof include iodine and organic dyes. Organic dyes include, for example, Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First orange S, first black, etc. are mentioned.

  In the dyeing step, only one kind of dichroic substance may be used, or two or more kinds may be used in combination. In the case of using an organic dye, for example, it is preferable to combine two or more kinds from the viewpoint of achieving neutralization in the visible light region. As specific examples, for example, combinations of Congo Red and Spula Blue G, Spula Orange GL and Direct Sky Blue, Direct Sky Blue and First Black, and the like can be given.

  When iodine is used as the dichroic substance, the dye bath solution preferably further contains an auxiliary agent such as iodide. This is because the dyeing efficiency is improved. Specific examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Titanium is mentioned. Among these, potassium iodide is preferable. The auxiliary is preferably used in a proportion of 0.02 to 20 parts by weight, more preferably 0.01 to 10 parts by weight, and still more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the solvent. The ratio (weight ratio) of iodine and auxiliary agent (preferably potassium iodide) is preferably 1: 5 to 1: 100, more preferably 1: 6 to 1:80, still more preferably 1: 7 to 1:70. It is.

  The temperature of the dyeing bath is preferably 5 to 70 ° C, more preferably 5 to 42 ° C, and still more preferably 10 to 35 ° C. The immersion time in the dyeing bath is preferably 1 to 20 minutes, more preferably 2 to 10 minutes.

  In the dyeing process, the film may be stretched in a dyeing bath. The total draw ratio accumulated at this time is preferably 1.1 to 4.0 times.

  As the dyeing process in the dyeing process, in addition to the method of immersing in the dyeing bath as described above, for example, a method of applying or spraying an aqueous solution containing a dichroic substance onto a polyvinyl alcohol resin film may be used. Moreover, it is also possible to mix a dichroic substance in advance at the time of film formation in the previous step. In this case, the pre-process and the dyeing process are performed at the same time.

  When pulling up the film from the dyeing bath, any appropriate liquid break roll such as a pinch roll may be used as necessary to prevent the occurrence of dripping, or the liquid may be removed with an air knife. Excess water may be removed by a method such as scraping off.

(Crosslinking process)
The crosslinking step is typically performed by immersing the dyed polyvinyl alcohol resin film in a treatment bath (crosslinking bath) containing a crosslinking agent. Arbitrary appropriate crosslinking agents can be employ | adopted as a crosslinking agent. Specific examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These can be used alone or in combination. When combining two or more types, for example, a combination of boric acid and borax is preferable, and the combination ratio (molar ratio) is preferably 4: 6 to 9: 1, more preferably 5.5: 4.5. -7: 3, more preferably 5.5: 4.5-6.5-3.5.

  As the solvent used for the solution of the crosslinking bath, water is generally used, but an appropriate amount of an organic solvent having compatibility with water may be added. The crosslinking agent is typically used at a ratio of 1 to 10 parts by weight with respect to 100 parts by weight of the solvent. When the concentration of the crosslinking agent is less than 1 part by weight, sufficient optical properties cannot often be obtained. When the concentration of the crosslinking agent exceeds 10 parts by weight, the stretching force generated in the film at the time of stretching increases, and for example, the obtained polarizing plate may shrink.

  It is preferable that the solution of the crosslinking bath further contains an auxiliary agent containing potassium iodide as an essential component. This is because it is easy to obtain uniform characteristics in the plane. The concentration of the auxiliary agent is preferably 0.05 to 15% by weight, more preferably 0.1 to 10% by weight, and still more preferably 0.5 to 8% by weight. Examples of auxiliary agents other than potassium iodide include lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Titanium is mentioned. Only one of these may be used, or two or more may be used in combination.

  The temperature of the crosslinking bath is preferably 20 to 70 ° C, more preferably 40 to 60 ° C. The immersion time of the film in the crosslinking bath is preferably 1 second to 15 minutes, more preferably 5 seconds to 10 minutes.

  In the cross-linking step, a method of applying or spraying a cross-linking agent-containing solution onto the film may be employed as in the dyeing step. In the crosslinking step, the film may be stretched in a crosslinking bath. The total draw ratio accumulated at this time is preferably 1.1 to 4.0 times.

  When pulling up the film from the cross-linking bath, any appropriate liquid break roll such as a pinch roll may be used as necessary in order to prevent the occurrence of dripping. Excess water may be removed by a method such as scraping off.

(Stretching process)
The stretching process is a process of stretching the polyvinyl alcohol-based resin film. The stretching process may be performed at any stage as described above. Specifically, it may be performed after the dyeing process, may be performed before the dyeing process, may be performed simultaneously with the swelling process, the dyeing process, and the crosslinking process, or may be performed after the crosslinking process.

  The cumulative draw ratio of the polyvinyl alcohol-based resin film is preferably 2 to 7 times, more preferably 5 to 7 times, and still more preferably 5 to 6.5 times. When the cumulative draw ratio is less than 2, it may be difficult to obtain a polarizing plate with a high degree of polarization. When the cumulative draw ratio exceeds 7 times, the polyvinyl alcohol-based resin film (polarizer) may be easily broken. The thickness of the stretched film is preferably 3 to 75 μm, more preferably 5 to 50 μm.

  Arbitrary appropriate methods may be employ | adopted as a specific method of extending | stretching. Examples thereof include a wet stretching method in which a polyvinyl alcohol resin film is stretched in a warm aqueous solution, and a dry stretching method in which the water-containing polyvinyl alcohol resin film is stretched in air. When the wet stretching method is adopted, the polyvinyl alcohol-based resin film is stretched at a predetermined magnification in a treatment bath (stretching bath).

  As the solution for the stretching bath, a solution containing potassium iodide in a solvent such as water or an organic solvent (for example, ethanol) is preferably used. Other than potassium iodide, for example, various metal salts, boron or zinc compounds, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide , Tin iodide, and titanium iodide may be included in one or more of these. Among these, it is preferable to contain boric acid. The concentration of potassium iodide is preferably 0.05 to 15% by weight, more preferably 0.1 to 10% by weight, and still more preferably 0.5 to 8% by weight. When boric acid and potassium iodide are used in combination, the combination ratio (weight ratio) is preferably 1: 0.1 to 1: 4, more preferably 1: 0.5 to 1: 3.

  The temperature of the stretching bath is preferably 30 to 70 ° C, more preferably 40 to 67 ° C, and further preferably 50 to 62 ° C. In the case of dry stretching, 50 to 180 ° C. is preferable.

  When pulling up the film from the stretching bath, any appropriate liquid break roll such as a pinch roll may be used as necessary to prevent the occurrence of dripping, or the liquid may be removed with an air knife. Excess water may be removed by a method such as scraping off.

(Washing process)
The washing step is typically performed by immersing the polyvinyl alcohol-based resin film subjected to the above-described various treatments in a treatment bath (water washing bath). An unnecessary residue of the polyvinyl alcohol-based resin film can be washed away by the washing step. The washing bath is an aqueous solution containing potassium iodide as an essential component. Other than potassium iodide, for example, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, One or more of these may be included. The concentration of potassium iodide is preferably 0.05 to 15% by weight, more preferably 0.1 to 10% by weight, still more preferably 3 to 8% by weight, and particularly preferably 0.5 to 8% by weight. An auxiliary agent such as zinc sulfate or zinc chloride may be added to the aqueous iodide solution.

  The temperature of the washing bath is preferably 10 to 60 ° C, more preferably 15 to 40 ° C, and further preferably 30 to 40 ° C. The immersion time is preferably 1 second to 1 minute. The cleaning step may be performed only once, or may be performed a plurality of times as necessary. When implemented several times, the kind and density | concentration of the additive contained in the washing bath used for each process can be adjusted suitably. For example, the washing step includes a step of immersing the polymer film in an aqueous potassium iodide solution (0.1 to 10% by weight, 10 to 60 ° C.) for 1 second to 1 minute, and a step of rinsing with pure water.

  When pulling up the film from the washing bath, any appropriate liquid break roll such as a pinch roll may be used as necessary in order to prevent the occurrence of dripping. Excess water may be removed by a method such as scraping off.

(Drying process)
Any appropriate drying method (for example, natural drying, air drying, heat drying, etc.) can be adopted as the drying step. Heat drying is preferred. In the case of heat drying, the drying temperature is preferably 20 to 80 ° C, more preferably 20 to 60 ° C, still more preferably 20 to 45 ° C, and the drying time is preferably 1 to 10 minutes. A polarizer is obtained as described above.

C. Transparent Protective Film As described above, practically, on one side of the first polarizer 30 (the side where the first birefringent layer is not disposed), a transparent protective film (the transparent protective film 10 in FIG. 1) is provided. Can be provided. Further, as shown in FIG. 1, when the liquid crystal panel of the present invention has the second polarizer 50, a transparent protective film (in FIG. 1, a transparent protective film) is provided on at least one side of the second polarizer 50. Films 11, 12) may be provided. By providing a transparent protective film, deterioration of the polarizer can be prevented.

  Any appropriate protective film can be adopted as the transparent protective film. Examples of the material constituting the transparent protective film include thermoplastic resins that are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and the like. Specific examples of such thermoplastic resins include acetate resins such as triacetyl cellulose (TAC), polyester resins, polyether sulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, poly Examples include norbornene resin, cellulose resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyacrylic resin, and mixtures thereof. Also, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may be used. From the viewpoint of polarization properties and durability, a cellulose film (such as a TAC film whose surface has been saponified with an alkali or the like) or an acrylic film is preferable.

  As the acrylic film, a film made of any appropriate acrylic resin can be adopted.

  As said acrylic resin, Tg (glass transition temperature) becomes like this. Preferably it is 115 degreeC or more, More preferably, it is 120 degreeC or more, More preferably, it is 125 degreeC or more, Most preferably, it is 130 degreeC or more. If Tg is 115 ° C. or higher, the durability can be excellent. Although the upper limit of Tg of the said (meth) acrylic-type resin is not specifically limited, From viewpoints of a moldability etc., Preferably it is 170 degrees C or less.

  The acrylic film made of the acrylic resin as a material can have an in-plane retardation (Δnd) and a thickness direction retardation (Rth) of preferably almost zero (0).

Any appropriate acrylic resin can be adopted as the acrylic resin within a range not impairing the effects of the present invention. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester -(Meth) acrylic acid copolymer, (meth) acrylic acid methyl-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer) And methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, poly (meth) acrylic acid C _1-6 alkyl such as poly (meth) acrylate methyl is used. More preferably, a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

  Specific examples of the acrylic resin include, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and (meth) acrylic resins having a ring structure in the molecule described in JP-A-2004-70296, molecules Examples thereof include high Tg (meth) acrylic resins obtained by internal crosslinking or intramolecular cyclization reaction.

  As the acrylic resin, a (meth) acrylic resin having a lactone ring structure can be used. Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

  As the acrylic resin, a (meth) acrylic resin having a structural unit derived from an unsaturated carboxylic acid alkyl ester and a structural unit derived from glutaric anhydride can be used. Examples of such a (meth) acrylic resin include JP-A-2004-70290, JP-A-2004-70296, JP-A-2004-163924, JP-A-2004-292812, and JP-A-2005-314534. JP, JP-A-2006-131898, JP-A-2006-206881, JP-A-2006-265532, JP-A-2006-283013, JP-A-2006-299905, JP-A-2006-335902, etc. (Meth) acrylic resin described in 1.

  As the acrylic resin, a (meth) acrylic resin having a structural unit derived from glutarimide, a structural unit derived from (meth) acrylic acid ester, and a structural unit derived from aromatic vinyl can be used. Examples of such (meth) acrylic resins include JP 2006-309033 A, JP 2006-317560 A, JP 2006-328329 A, JP 2006-328334 A, and JP 2006-337491 A. Examples thereof include (meth) acrylic resins described in JP-A-2006-337492, JP-A-2006-337493, JP-A-2006-337569, and the like.

  Furthermore, for example, a polymer film formed from a resin composition as described in JP-A-2001-343529 (WO 01/37007) can also be used as a protective film. More specifically, it is a mixture of a thermoplastic resin having a substituted imide group or an unsubstituted imide group in the side chain and a thermoplastic resin having a substituted phenyl group or an unsubstituted phenyl group and a cyano group in the side chain. Specific examples include a resin composition having an alternating copolymer composed of isobutene and N-methylenemaleimide and an acrylonitrile / styrene copolymer. For example, an extruded product of such a resin composition can be used.

  The transparent protective film is preferably transparent and not colored. Specifically, the thickness direction retardation Rth of the transparent protective film is preferably −90 nm to +75 nm, more preferably −80 nm to +60 nm, and most preferably −70 nm to +45 nm. When the retardation Rth in the thickness direction of the transparent protective film is within such a range, the optical coloring of the polarizer caused by the transparent protective film can be eliminated.

  The thickness of the transparent protective film can be appropriately set according to the purpose. The thickness of the transparent protective film is typically 500 μm or less, preferably 5 to 300 μm, and more preferably 5 to 150 μm.

  A preferred form of lamination of the first polarizer or the second polarizer and the transparent protective film is such that the first polarizer or the second polarizer is bonded to the transparent protective film via an adhesive layer. .

  Arbitrary appropriate adhesives can be employ | adopted as an adhesive agent which comprises the said adhesive bond layer. For example, a polyvinyl alcohol-type adhesive agent is mentioned. The polyvinyl alcohol-based adhesive contains a polyvinyl alcohol-based resin and a crosslinking agent. Moreover, you may employ | adopt the polyvinyl alcohol-type adhesive agent containing a metal compound colloid as mentioned later.

  The polyvinyl alcohol-based resin is not particularly limited. For example, polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; and a saponified product of a copolymer with a monomer having copolymerizability with vinyl acetate. Modified polyvinyl alcohol obtained by acetalization, urethanization, etherification, grafting, phosphoric esterification, etc. of polyvinyl alcohol. Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives, and the like. . These polyvinyl alcohol resins may be used alone or in combination of two or more.

  From the viewpoint of adhesiveness, the polyvinyl alcohol-based resin preferably has an average degree of polymerization of 100 to 3000, more preferably 500 to 3000, and an average degree of saponification of preferably 85 to 100 mol%, more preferably 90. ˜100 mol%.

  As the polyvinyl alcohol resin, a polyvinyl alcohol resin having an acetoacetyl group can be used. A polyvinyl alcohol-based resin having an acetoacetyl group is a polyvinyl alcohol-based adhesive having a highly reactive functional group, and is preferable in terms of improving the durability of the obtained optical film. Specific examples of the above-mentioned polyvinyl alcohol resin having an acetoacetyl group include the product name “GOHSENOL Z series” manufactured by Nippon Synthetic Chemical Co., Ltd., the product name “GOHSENOL NH series”, and the product name “GOHSEPIMAR”. Z series ".

  A polyvinyl alcohol-based resin containing an acetoacetyl group is obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. For example, a method in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid and diketene is added thereto, and a polyvinyl alcohol resin is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. And the like. Moreover, the method of making diketene gas or liquid diketene contact directly to polyvinyl alcohol is mentioned.

  The degree of acetoacetyl group modification of the polyvinyl alcohol resin having an acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. If it is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient, which is inappropriate. The degree of acetoacetyl modification is preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%. When the degree of acetoacetyl modification exceeds 40 mol%, the number of reaction points with the cross-linking agent decreases, and the effect of improving water resistance is small. The degree of acetoacetyl modification is a value measured by NMR.

As said crosslinking agent, what is used for the polyvinyl alcohol-type adhesive agent can be especially used without a restriction | limiting.
As the crosslinking agent, a compound having at least two functional groups having reactivity with the polyvinyl alcohol resin can be used. For example, alkylene diamines having two alkylene groups and two amino groups such as ethylene diamine, triethylene amine, hexamethylene diamine (hexamethylene diamine is preferred); tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylene propane tolylene Isocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane triisocyanate, isophorone diisocyanate and isocyanates such as ketoxime block or phenol block; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di Or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylo Epoxys such as rupropane triglycidyl ether, diglycidyl aniline, diglycidyl amine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleidialdehyde , Dialdehydes such as phthaldialdehyde; amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, condensates of benzoguanamine and formaldehyde; sodium, potassium, magnesium Divalent metals such as calcium, aluminum, iron and nickel, or salts of trivalent metals and oxides thereof. In particular, melamine-based cross-linking agents are preferable, and methylol melamine is particularly preferable. Specific examples of the amines include trade name “metaxylene diamine” manufactured by Mitsubishi Gas Chemical Co., Ltd. Specific examples of the methylol compounds include Dainippon Ink Co., Ltd. Product name “Watersol Series” and the like.

  The amount of the crosslinking agent is preferably 1 to 60 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin (preferably acetoacetyl group-containing polyvinyl alcohol resin). The upper limit of the blending amount is more preferably 50 parts by weight, further preferably 30 parts by weight, further preferably 15 parts by weight, particularly preferably 10 parts by weight, and most preferably 7 parts by weight. It is. The lower limit of the amount is more preferably 5 parts by weight, still more preferably 10 parts by weight, and particularly preferably 20 parts by weight. By setting it as said range, the adhesive bond layer excellent in transparency, adhesiveness, and water resistance can be formed. In addition, when there are many compounding quantities of a crosslinking agent, reaction of a crosslinking agent advances in a short time, and there exists a tendency for an adhesive agent to gelatinize. As a result, the usable time (pot life) as an adhesive becomes extremely short, and industrial use may be difficult. However, when a metal compound colloid described later is used in combination, it can be used with good stability even when the amount of the crosslinking agent is large.

  The polyvinyl alcohol-based adhesive further includes coupling agents such as silane coupling agents and titanium coupling agents, various tackifiers, ultraviolet absorbers, antioxidants, heat stabilizers, hydrolysis stabilizers, and the like. A stabilizer or the like can also be blended.

  The surface that is in contact with the first polarizer 30 (preferably, the transparent protective film surface of the laminate A or the polarizer protective film surface) can be subjected to an easy adhesion treatment in order to improve adhesion. Examples of the easy adhesion treatment include surface treatment such as corona treatment, plasma treatment, low-pressure UV treatment, and saponification treatment, and a method of forming an anchor layer, and these can be used in combination. Among these, a corona treatment, a method of forming an anchor layer, and a method of using these in combination are preferable.

  Examples of the anchor layer include a silicone layer having a reactive functional group. The material of the silicone layer having a reactive functional group is not particularly limited. For example, an isocyanate group-containing alkoxysilanol, an amino group-containing alkoxysilanol, a mercapto group-containing alkoxysilanol, a carboxy-containing alkoxysilanol, an epoxy group-containing Examples thereof include alkoxysilanols, vinyl-type unsaturated group-containing alkoxysilanols, halogen group-containing alkoxylanols, and isocyanate group-containing alkoxysilanols, and amino silanols are preferred. Furthermore, the adhesive force can be strengthened by adding a titanium-based catalyst or a tin-based catalyst for efficiently reacting the silanol. Moreover, you may add another additive to the silicone which has the said reactive functional group. Specifically, terpene resins, phenol resins, terpene-phenol resins, rosin resins, xylene resins and other tackifiers, UV absorbers, antioxidants, heat stabilizers and other stabilizers may be used.

  The silicone layer having the reactive functional group is formed by coating and drying by a known technique. The thickness of the silicone layer is preferably 1 to 100 nm, more preferably 10 to 50 nm after drying. During coating, silicone having a reactive functional group may be diluted with a solvent. The dilution solvent is not particularly limited, and examples thereof include alcohols. The dilution concentration is not particularly limited, but is preferably 1 to 5% by weight, more preferably 1 to 3% by weight.

  The adhesive layer is formed by applying an adhesive (for example, the polyvinyl alcohol-based adhesive described above or a polyvinyl alcohol-based adhesive containing a metal compound colloid as described later) to the polarizer of the transparent protective film. It is preferable to carry out by applying to any one of the adhesive surface side, the adhesive surface side of the polarizer to the transparent protective film, or both sides thereof. After laminating the polarizer and the transparent protective film, it is preferable that a drying process is performed to form an adhesive layer composed of a coated and dried layer. This can also be bonded after forming the adhesive layer. The bonding can be performed with a roll laminator or the like. The heating and drying temperature and drying time are appropriately determined according to the type of adhesive.

  The thickness of the adhesive layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm, because it is not preferable in terms of adhesiveness when the thickness after drying becomes too thick.

D. A birefringent layer (first birefringent layer) made of a cyclic olefin-based film in which the Nz coefficient defined by Nz = (nx−nz) / (nx−ny) has a relationship of 1 <Nz ≦ 2.

  In the first birefringent layer, the Nz coefficient defined by Nz = (nx−nz) / (nx−ny) has a relationship of 1 <Nz ≦ 2. Preferably 1.1 ≦ Nz ≦ 1.7, more preferably 1.1 ≦ Nz ≦ 1.4. Since the first birefringent layer has a relationship of 1 <Nz ≦ 2, a liquid crystal suitable for a liquid crystal display device capable of obtaining a neutral display having no color in all directions by being combined with a specific second birefringent layer Panels can be provided. The first birefringent layer is preferably a λ / 4 plate.

  The in-plane retardation of the first birefringent layer is preferably 90 to 160 nm, more preferably 95 to 150 nm, and further preferably 95 to 145 nm.

  The thickness of the first birefringent layer can be set so as to obtain a desired in-plane retardation. Specifically, the thickness of the first birefringent layer is preferably 20 to 110 μm, more preferably 25 to 105 μm, and most preferably 30 to 100 μm.

  Examples of the resin that can form the first birefringent layer include cyclic olefin resins. Specifically, the first birefringent layer is a cyclic olefin film.

  The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers). And graft modified products in which these are modified with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. 2-Norbornene, 5-ethylidene-2-norbornene, and the like, polar substituents such as halogens thereof; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; 3-pentamer of cyclopentadiene, for example, 4,9: 5,8-dimethano-3a, 4 4a, 5,8,8a, 9,9a-octahydro-1H-benzoin 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene and the like. It is done.

  In the present invention, other cycloolefins capable of ring-opening polymerization can be used in combination as long as the object of the present invention is not impaired. Specific examples of such cycloolefins include compounds having one reactive double bond such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.

  The cyclic olefin-based resin preferably has a number average molecular weight (Mn) measured by a gel permeation chromatograph (GPC) method using a toluene solvent, preferably 25,000 to 200,000, more preferably 30,000 to 100,000. 000, most preferably 40,000-80,000. When the number average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

  When the cyclic olefin-based resin is obtained by hydrogenating a ring-opening polymer of a norbornene monomer, the hydrogenation rate is preferably 90% or more, more preferably 95% or more, Most preferably, it is 99% or more. Within such a range, the heat deterioration resistance and light deterioration resistance are excellent.

  As the cyclic olefin resin, various products are commercially available. Specific examples include trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, “Arton” manufactured by JSR, “TOPAS” trade name manufactured by TICONA, and trade names manufactured by Mitsui Chemicals, Inc. “APEL” may be mentioned.

  The first birefringent layer can be obtained by stretching a film (cyclic olefin film) formed from the cyclic olefin resin. Any appropriate forming method can be adopted as a method for forming the cyclic olefin-based film. Specific examples include compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method, casting method (casting) method and the like. An extrusion method or a casting method is preferred. This is because the smoothness of the resulting film can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, the characteristics desired for the first birefringent layer, and the like. In addition, since many film products are marketed, the said cyclic olefin type film may use the said commercial film as it is for a extending | stretching process.

  The cyclic olefin-based film may be a free-end stretched film or a fixed-end stretched film. A fixed end stretched film is preferred. By performing the fixed end stretching, it is easy to obtain a film having an Nz coefficient of 1 <Nz ≦ 2. Further, by performing fixed end stretching, a slow axis can be provided in the short direction (width direction) of the film, so that the slow axis of the film is arranged to be orthogonal to the absorption axis of the polarizer. In this case, the film and the polarizer can be bonded to each other continuously by a roll-to-roll process, and the production efficiency is increased.

  The draw ratio of the cyclic olefin resin film is preferably 1.2 to 4.0 times, more preferably 1.2 to 3.8 times, and most preferably 1.25 to 3.6 times. By stretching at such a magnification, a first birefringent layer that can appropriately exhibit the effects of the present invention can be obtained. When the draw ratio is less than 1.2 times, the desired in-plane retardation required for the first birefringent layer may not be exhibited. When the draw ratio is larger than 4.0 times, the film may be cut or become brittle during drawing.

  The stretching temperature of the cyclic olefin resin film is preferably 130 to 165 ° C, more preferably 135 to 165 ° C, and most preferably 137 to 165 ° C. By extending | stretching at such temperature, the 1st birefringent layer which can exhibit the effect of this invention appropriately can be obtained. When the stretching temperature is lower than 130 ° C., there is a possibility that uniform stretching cannot be performed. If the stretching temperature is higher than 165 ° C., the desired in-plane retardation required for the first birefringent layer may not be exhibited.

E. Lamination of first birefringent layer and first polarizer The first polarizer and the first birefringent layer are laminated directly via a polyvinyl alcohol-based adhesive containing a metal compound colloid. . Referring to FIG. 1 as an example, a first polarizer 30 and a first birefringent layer 60 are directly laminated via a polyvinyl alcohol-based adhesive containing a metal compound colloid.

  The lamination surface of the first birefringent layer on the first polarizer is preferably subjected to an easy adhesion treatment. As the easy adhesion treatment, it is preferable to apply a resin material. As the resin material, for example, a silicon resin, a urethane resin, and an acrylic resin are preferable. By performing the easy adhesion treatment, an easy adhesion layer is formed. The thickness of the easy adhesion layer is preferably 5 to 100 nm, more preferably 10 to 80 nm.

  The polyvinyl alcohol-based adhesive containing a metal compound colloid may be applied to the first polarizer side, may be applied to the first birefringent layer side, and the first polarizer and It may be applied to both sides of the first birefringent layer.

  The adhesive layer is formed, for example, by applying and drying a coating liquid containing an adhesive at a predetermined ratio on the surface of the first optical compensation layer and / or the surface of the first polarizer. The Any appropriate method can be adopted as a method for preparing the coating liquid. For example, a commercially available solution or dispersion may be used, a solvent may be added to the commercially available solution or dispersion, and the solid content may be dissolved or dispersed in various solvents.

  The polyvinyl alcohol-based adhesive containing the metal compound colloid further contains a metal compound colloid in the polyvinyl alcohol-based adhesive (water-soluble adhesive mainly composed of a polyvinyl alcohol-based resin). The metal compound colloid may be one in which metal compound fine particles are dispersed in a dispersion medium, and is electrostatically stabilized due to mutual repulsion of the same kind of charge of the fine particles, and has permanent stability. obtain.

  The average particle size of the fine particles forming the metal compound colloid can be any appropriate value as long as it does not adversely affect the optical properties such as polarization properties. Preferably it is 1-100 nm, More preferably, it is 1-50 nm. This is because the fine particles can be uniformly dispersed in the adhesive layer, the adhesion can be ensured, and the nick can be suppressed. The “knic” refers to a local uneven defect generated at the interface between the polarizer and the protective layer.

  Any appropriate compound can be adopted as the metal compound. For example, metal oxides such as alumina, silica, zirconia and titania; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate and calcium phosphate; minerals such as celite, talc, clay and kaolin It is done. Alumina is preferred.

  The metal compound colloid is typically present in the form of a colloidal solution dispersed in a dispersion medium. Examples of the dispersion medium include water and alcohols. The solid concentration in the colloidal solution is preferably 1 to 50% by weight. The colloidal solution can contain acids such as nitric acid, hydrochloric acid, acetic acid as stabilizers.

  The compounding amount of the metal compound colloid (solid content) is preferably 200 parts by weight or less, more preferably 10 to 200 parts by weight, still more preferably 20 to 175 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin. Most preferably, it is 30-150 weight part. This is because the occurrence of nicks can be suppressed while ensuring adhesiveness.

  Arbitrary appropriate methods can be employ | adopted as a preparation method of the said adhesive agent. For example, in the case of an adhesive containing a metal compound colloid, for example, a method in which the metal compound colloid is mixed with a polyvinyl alcohol resin and a crosslinking agent mixed in advance and adjusted to an appropriate concentration. . Moreover, after mixing a polyvinyl alcohol-type resin and a metal compound colloid, a crosslinking agent can also be mixed considering the time of use etc. The concentration of the resin solution may be adjusted after preparing the resin solution.

  The resin concentration of the adhesive is preferably 0.1 to 15% by weight, more preferably 0.5 to 10% by weight, from the viewpoints of coatability and storage stability.

  The pH of the adhesive is preferably 2 to 6, more preferably 2.5 to 5, further preferably 3 to 5, and most preferably 3.5 to 4.5. Usually, the surface charge of the metal compound colloid can be controlled by adjusting the pH. The surface charge is preferably a positive charge. By having a positive charge, for example, generation of nicks can be suppressed.

  The total solid content concentration of the adhesive may vary depending on the solubility, coating viscosity, wettability, target thickness, and the like of the adhesive. The total solid content concentration with respect to the solvent 100 is preferably 2 to 100 (weight ratio), more preferably 10 to 50 (weight ratio), and further preferably 20 to 40 (weight ratio). If it is such a range, an adhesive layer with high surface uniformity will be obtained.

  Arbitrary appropriate viscosity can be employ | adopted as a viscosity of the said adhesive agent. For example, the value measured at a shear rate of 1000 (1 / s) at 23 ° C. is preferably 1 to 50 (mPa · s), more preferably 2 to 30 (mPa · s), and even more preferably 4 ~ 20 (mPa · s). If it is said range, the adhesive bond layer excellent in surface uniformity can be formed.

  Any appropriate method can be adopted as a method for applying the adhesive. For example, a coating method using a coater can be used. The coater to be used can be appropriately selected from the coaters described above.

  Any appropriate temperature can be adopted as the glass transition temperature (Tg) of the adhesive. Preferably it is 20-120 degreeC, More preferably, it is 40-100 degreeC, More preferably, it is 50-90 degreeC. In addition, a glass transition temperature can be measured by the method according to JISK7121-1987 by differential scanning calorimetry (DSC) measurement.

  Any appropriate thickness can be adopted as the thickness of the adhesive layer. Preferably it is 0.01-0.15 micrometer, More preferably, it is 0.02-0.12 micrometer, More preferably, it is 0.03-0.09 micrometer. If it is said range, it will be excellent in durability even if it exposes to a hot and humid environment, and a polarizer will not peel or float.

  The adhesive may contain a coupling agent such as a silane coupling agent and a titanium coupling agent, various tackifiers, an ultraviolet absorber, an antioxidant, a heat stabilizer, a hydrolysis stabilizer, and the like. .

F. Birefringent layer (second birefringent layer) having a relationship of nx = ny> nz
The second birefringent layer preferably has a relationship of nx = ny> nz. The second birefringent layer may be a single layer or a laminate of two or more layers. In the case of a laminate, the material constituting each layer and the thickness of each layer can be appropriately set as long as the entire laminate has the optical characteristics as described above.

  When the second birefringent layer has a relationship of nx = ny> nz, it can function as a so-called negative C plate. When the second birefringent layer has such a refractive index distribution, the object of the present invention can be effectively achieved by a combination with the specific first birefringent layer. As described above, in the present specification, “nx = ny” includes not only the case where nx and ny are exactly equal, but also the case where they are substantially equal. It may have a phase difference and may have a slow axis. The in-plane retardation Δnd that is practically acceptable for the negative C plate is preferably 0 to 20 nm, more preferably 0 to 10 nm, and further preferably 0 to 5 nm.

  The thickness direction retardation Rth of the second birefringent layer is preferably 30 to 350 nm, more preferably 60 to 300 nm, still more preferably 80 to 260 nm, and most preferably 100 to 240 nm.

  The thickness of the second birefringent layer from which the thickness direction retardation as described above can be obtained can vary depending on the material used. For example, the thickness of the second birefringent layer is preferably 1 to 50 μm, more preferably 1 to 20 μm, still more preferably 1 to 15 μm, still more preferably 1 to 10 μm, and particularly preferably. It is 1-8 micrometers, Most preferably, it is 1-5 micrometers. Such a thickness is thinner than the thickness (for example, 60 μm or more) of the negative C plate by biaxial stretching, and can greatly contribute to the thinning of the image display device. Furthermore, by forming the second birefringent layer very thin, heat unevenness can be remarkably prevented.

  As a material constituting the second birefringent layer, any appropriate material can be adopted as long as the above optical characteristics can be obtained. Preferably, the second birefringent layer is a coating layer of a non-liquid crystalline material. This is because the thickness can be remarkably reduced as compared with the stretched film, which can contribute to the thinning of the liquid crystal panel. Preferably, the non-liquid crystalline material is a non-liquid crystalline polymer. When such a non-liquid crystalline material is used for the coating layer, unlike the liquid crystalline material, a film exhibiting optical uniaxial properties of nx> nz and ny> nz depending on the properties of the substrate, regardless of the orientation of the substrate. Can be formed. As a result, not only an oriented substrate but also an unoriented substrate can be used. Furthermore, even when an unoriented substrate is used, the step of applying an alignment film on the surface, the step of laminating the alignment film, and the like can be omitted.

  As the non-liquid crystalline material, for example, polymers such as polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide exemplified in paragraphs (0018) to (0072) of JP-A-2004-46065 are preferable. This is because these polymers are excellent in heat resistance, chemical resistance, transparency, and rich in rigidity. Any one of these polymers may be used alone, or a mixture of two or more having different functional groups such as a mixture of polyaryletherketone and polyamide may be used. . Among such polymers, polyimide is particularly preferable because of its high transparency, high orientation, and high stretchability.

  The molecular weight of the polymer is not particularly limited. For example, the weight average molecular weight (Mw) is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 2,000 to 500,000. is there.

  Next, a method for manufacturing the second birefringent layer will be described. As a method for producing the second birefringent layer, any appropriate method can be adopted as long as the effects of the present invention can be obtained.

  The second birefringent layer preferably includes at least one non-liquid crystal material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide. The solution containing the non-liquid crystal material is preferably applied to the transparent polymer film and then dried to form the polymer layer on the transparent polymer film, whereby the second nx = ny> nz relationship is established. A birefringent layer is obtained.

  A typical method for producing the second birefringent layer includes a step of applying a solution of the non-liquid crystalline polymer to a base film, and a solvent in the solution is removed to form a layer of the non-liquid crystalline polymer. Process. The non-liquid crystalline polymer layer may be formed by coating directly on a polarizing plate (typically, a polarizer protective layer) (that is, the polarizer protective layer may also serve as a base film). ), It may be formed on any suitable substrate and then transferred to a polarizer (typically a protective layer for the polarizer). The method by transfer may further include peeling the substrate.

  Any appropriate film can be adopted as the base film. As a typical substrate film, a plastic film used for the protective layer of the polarizer described above can be cited. The protective layer of the polarizer itself may also serve as the base film.

  The solvent of the coating solution (polymer solution to be applied to the transparent polymer film) is not particularly limited. For example, halogen such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene, etc. Hydrocarbons; phenols such as phenol and parachlorophenol; aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopenta Ketone solvents such as non-, 2-pyrrolidone and N-methyl-2-pyrrolidone; ester solvents such as ethyl acetate and butyl acetate; t-butyl alcohol, glycerin, ethylene glycol, Alcohol solvents such as reethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol and 2-methyl-2,4-pentanediol; amide solvents such as dimethylformamide and dimethylacetamide; acetonitrile and butyronitrile Nitrile solvents such as: ether solvents such as diethyl ether, dibutyl ether, and tetrahydrofuran; carbon disulfide, ethyl cellosolve, butyl cellosolve, and the like. Of these, methyl isobutyl ketone is preferred. This is because it exhibits high solubility in non-liquid crystal materials and does not erode the substrate. These solvents may be used alone or in combination of two or more.

  As the concentration of the non-liquid crystalline polymer in the coating solution, any appropriate concentration can be adopted as long as the second birefringent layer as described above is obtained and coating is possible. For example, the solution preferably contains 5 to 50 parts by weight, more preferably 10 to 40 parts by weight of the non-liquid crystalline polymer with respect to 100 parts by weight of the solvent. A solution having such a concentration range has a viscosity that is easy to apply.

  The coating solution may further contain various additives such as a stabilizer, a plasticizer, and metals as necessary.

  The coating solution may further contain other different resins as necessary. Examples of such other resins include various general-purpose resins, engineering plastics, thermoplastic resins, and thermosetting resins. By using such a resin in combination, it is possible to form an optical compensation layer having appropriate mechanical strength and durability depending on the purpose.

  Examples of the general-purpose resin include polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), ABS resin, and AS resin. Examples of the engineering plastic include polyacetate (POM), polycarbonate (PC), polyamide (PA: nylon), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). Examples of the thermoplastic resin include polyphenylene sulfide (PPS), polyethersulfone (PES), polyketone (PK), polyimide (PI), polycyclohexanedimethanol terephthalate (PCT), polyarylate (PAR), and liquid crystal polymer. (LCP) and the like. As said thermosetting resin, an epoxy resin, a phenol novolak resin, etc. are mentioned, for example.

  The kind and amount of the different resin added to the coating solution can be appropriately set according to the purpose. For example, such a resin can be added in a proportion of preferably 0 to 50% by weight, more preferably 0 to 30% by weight, based on the non-liquid crystalline polymer.

  Examples of the coating method for the solution include spin coating, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, and gravure printing. Further, in the application, a polymer layer superposition method may be employed as necessary.

  After coating, for example, the solvent in the solution is evaporated and removed by drying such as natural drying, air drying, and heat drying (for example, 60 to 250 ° C.) to form a film-like optical compensation layer.

  Examples of the material constituting the second birefringent layer include poly (4,4′-hexafluoroisopropylidene-bisphenol) terephthalate-co-isophthalate, poly (4,4′-hexahydro-4,7-methanoindane). -5-ylidenebisphenol) terephthalate, poly (4,4'-isopropylidene-2,2 ', 6,6'-tetrachlorobisphenol) terephthalate-co-isophthalate, poly (4,4'-hexafluoroisopropylidene Ridene) -bisphenol-co- (2-norbornylidene) -bisphenol terephthalate, poly (4,4′-hexahydro-4,7-methanoindane-5-ylidene) -bisphenol-co- (4,4′-isopropylidene-2 , 2 ′, 6,6′-tetrabromo) -bisphenol terephthalate Over DOO, poly (4,4'-isopropylidene - bisphenol - co-4,4 '- (2-norbornylidene) bisphenol) terephthalate - co - isophthalate or may be employed as copolymers thereof. These may be used alone or in combination of two or more.

G. Lamination of Second Birefringent Layer and Second Polarizer As described above, the second birefringent layer in the present invention can be preferably formed as a coating layer on a substrate. When the substrate also serves as a protective layer for the polarizer (for example, when the substrate is a cellulose-based film such as a triacetyl cellulose film), the side opposite to the coating layer of the substrate is the second polarizer and the adhesive. It is preferable to be laminated directly via In the case where the substrate does not serve as a protective layer for the polarizer, it is preferable to transfer it to the second polarizer (typically, the protective layer for the second polarizer) and peel the substrate. Details of the adhesive are as described above.

H. Lamination of the liquid crystal cell and the first birefringent layer or the second birefringent layer The first birefringent layer or the second birefringent layer on the laminating surface side of the liquid crystal cell is in close contact with the liquid crystal cell. Preferably it has an adhesive layer.

  The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is used as a base polymer. It can select suitably and 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 being excellent in weather resistance and heat resistance can be preferably used. In particular, an acrylic pressure-sensitive adhesive made of an acrylic polymer having 4 to 12 carbon atoms is preferable.

  In addition to the above, from the viewpoints of prevention of foaming phenomenon and peeling phenomenon due to moisture absorption, deterioration of optical characteristics due to thermal expansion difference and the like, prevention of warpage of liquid crystal cell, and high-quality and durable liquid crystal display device. A pressure-sensitive adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The pressure-sensitive adhesive layer is, for example, a natural or synthetic resin, in particular, a tackifier resin, a filler or pigment made of glass fiber, glass beads, metal powder, other inorganic powders, a colorant, an antioxidant. An additive to be added to the pressure-sensitive adhesive layer such as an agent may be contained.

  The pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer containing fine particles and exhibiting light diffusibility.

  The attachment of the pressure-sensitive adhesive layer can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method of directly attaching it on an optical film (for example, the first birefringent layer) by an appropriate development method such as a casting method or a coating method, or forming an adhesive layer on a separator according to the above, Is transferred to the surface of the optical film (for example, the first birefringent layer).

  The pressure-sensitive adhesive layer can be provided on one side or both sides of an optical film (for example, the second birefringent layer) as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers, such as a different composition, a kind, and thickness, in the front and back of an optical film.

  The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is preferably 1 to 40 μm, more preferably 5 to 30 μm, and particularly preferably 10 to 25 μm. When the thickness is less than 1 μm, the durability is deteriorated. When the thickness is more than 40 μm, floating or peeling due to foaming or the like is liable to occur, resulting in poor appearance.

  In order to improve the adhesion between the optical film (for example, the first birefringent layer) and the pressure-sensitive adhesive layer, an anchor layer may be provided between the layers.

  As the anchor layer, an anchor layer selected from polyurethane, polyester and polymers containing an amino group in the molecule is preferably used, and polymers containing an amino group in the molecule are particularly preferably used. Polymers containing amino groups in the molecule are good because the amino groups in the molecule exhibit interactions such as reaction or ionic interaction with carboxyl groups in the adhesive and polar groups in the conductive polymer. Adhesion is ensured.

  Examples of the polymer containing an amino group in the molecule include, for example, polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, and amino-containing groups such as dimethylaminoethyl acrylate shown as a copolymer monomer of the acrylic pressure-sensitive adhesive. Examples thereof include polymers of contained monomers.

  In order to impart antistatic properties to the anchor layer, an antistatic agent may be added. Antistatic agents for imparting antistatic properties include ionic surfactant systems, conductive polymer systems such as polyaniline, polythiophene, polypyrrole, and polyquinoxaline, and metal oxide systems such as tin oxide, antimony oxide, and indium oxide. In particular, a conductive polymer system is preferably used from the viewpoint of optical characteristics, appearance, antistatic effect, and stability of the antistatic effect when heated and humidified. Among these, water-soluble conductive polymers such as polyaniline and polythiophene or water-dispersible conductive polymers are particularly preferably used. This is because, when a water-soluble conductive polymer or a water-dispersible conductive polymer is used as a material for forming the antistatic layer, it is possible to suppress deterioration of the optical film substrate due to an organic solvent during the coating process.

  In the present invention, each of the first polarizer 30, the first birefringent layer 60, the second polarizer 50, the second birefringent layer 70, the adhesive layer, the pressure-sensitive adhesive layer, etc. It may be one having a UV absorbing ability by a method such as a method of treating with a UV absorber such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex salt compound. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The measuring method of each characteristic in an Example is as follows.

<Measurement of phase difference>
Refractive indexes nx, ny and nz of the sample film are measured by an automatic birefringence measuring device (manufactured by Oji Scientific Instruments, automatic birefringence meter KOBRA-WPR), and in-plane retardation Δnd and thickness direction retardation Rth are calculated. did. The measurement temperature was 23 ° C. and the measurement wavelength was 590 nm.

<Measurement of contrast>
Using ELDIM product name “EZ Contrast 160D”, the polar angle is changed to 60 ° and the azimuth is changed from 0 to 360 °, and the contrast at the azimuths of 45 °, 135 °, 225 °, and 315 ° is measured. The average value was obtained. The azimuth angle and polar angle are as shown in FIG.

<Measurement of color shift>
Using ELDIM trade name “EZ Contrast 160D”, the color tone of the liquid crystal display device in which the azimuth angle was changed to 0 to 360 ° and the polar angle was set to 60 ° was measured and plotted on the xy chromaticity diagram.

<Measurement of black brightness>
Using ELDIM trade name “EZ Contrast 160D”, the azimuth angle was changed from −180 ° to 180 ° in the polar angle direction of 60 °, and the relationship between the azimuth angle and the black luminance was plotted.

<Knic evaluation>
After 30 minutes have passed since the backlight was turned on in a dark room at 23 ° C, the display surface when displaying black was visually observed, and the number of bright spots (knics) within 1000 mm x 1000 mm was visually counted. did.

[Reference Example 1]: Production of a polarizer (sometimes referred to as a first polarizer or a second polarizer) After a polyvinyl alcohol film is dyed in an aqueous solution containing iodine, the aqueous solution containing boric acid is used. A polarizer was produced by uniaxially stretching six times between rolls having different speed ratios.

Reference Example 2 Preparation of Polyvinyl Alcohol Adhesive Containing Metal Compound Colloid Acetoacetyl group-containing polyvinyl alcohol resin (trade name “Gosefimer Z200”, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree: 1200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%) 100 parts by weight, 50 parts by weight of methylolmelamine was dissolved in pure water under a temperature condition of 30 ° C., and the solid content concentration was 3 An aqueous solution adjusted to 7% was obtained. An aqueous adhesive solution was prepared by adding 18 parts by weight of an aqueous colloidal alumina solution (average particle size 15 nm, solid content concentration 10%, positive charge) to 100 parts by weight of this aqueous solution. The viscosity of the adhesive aqueous solution was 9.6 mPa · s. The pH of the aqueous adhesive solution was 4 to 4.5.

[Reference Example 3]: Preparation of Polyvinyl Alcohol-Based Adhesive A polyvinyl alcohol-based adhesive aqueous solution was prepared in the same manner as Reference Example 2 except that no alumina colloidal aqueous solution was added.

[Example 1]
(Preparation of polarizing plate integrated retardation film (1A))
A first birefringence is obtained by stretching a norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name: ZEONOR, model number: ZF14-100, thickness: 100 μm) at a fixed end of 2.6 times at 150 ° C. in the TD direction. A layer was made. The thickness of the first birefringent layer was 33 μm and Nz = 1.3 (Rth = 170 nm, Δnd = 130 nm).
The first polarizer was bonded so that the absorption axis of the first polarizer and the slow axis of the first birefringent layer were orthogonal to each other. Furthermore, a triacetyl cellulose (TAC) film (thickness: 80 μm) was bonded to the opposite side of the first polarizer from the first birefringent layer. Each layer was bonded via a polyvinyl alcohol-based adhesive (thickness: 0.1 μm) containing the metal compound colloid prepared in Reference Example 2.
(Preparation of polarizing plate integrated retardation film (1B))
From TAC substrate (thickness: 80 μm) to 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane) and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl A solution (concentration: 10% by weight) prepared by using methyl isobutyl ketone (MIBK) as a solvent was applied to the synthesized polyimide with a thickness of 30 μm. Thereafter, the substrate was dried at 120 ° C. for 10 minutes to obtain a base material-integrated second birefringent layer having a polyimide layer thickness of about 3 μm. The refractive index distribution of the obtained second birefringent layer was nx = ny> nz. A polyvinyl alcohol adhesive (thickness: 0.1 μm) containing the metal compound colloid prepared in Reference Example 2 is used on the substrate side of the substrate-integrated second birefringent layer, and a second polarizer is used. Were bonded so that the absorption axis of the second polarizer and the slow axis of the second birefringent layer were orthogonal to each other. Furthermore, the polyvinyl alcohol adhesive (thickness: 0) which prepared the triacetyl cellulose (TAC) film (thickness: 80 micrometers) on the opposite side to the 2nd birefringent layer of a 2nd polarizer in the reference example 3. 1 μm).
(Production of liquid crystal panel (1C))
A liquid crystal cell (VA mode) is taken out from the liquid crystal panel (SONY, BRAVIA, 32 inch panel), and the polarizing plate integrated retardation film (1A) and the polarizing plate are combined with an acrylic adhesive (thickness: 20 μm). Each of the body-type retardation films (1B) was bonded up and down with the liquid crystal cell interposed therebetween. At this time, it was made for the absorption axis of the polarizer contained in each of the said polarizing plate integrated retardation film (1A) and a polarizing plate integrated retardation film (1B) to orthogonally cross. Moreover, it bonded together so that the said polarizing plate integrated retardation film (1B) might become a backlight side, and a polarizing plate integrated retardation film (1A) might become a visual recognition side.
(Evaluation)
About the obtained liquid crystal panel (1C), the contrast was calculated | required according to said evaluation method. The results are shown in Table 1. Further, knick evaluation was performed according to the above evaluation method. The results are shown in Table 1.

[Example 2]
In Example 1, a triacetyl cellulose (TAC) film (thickness: 80 μm) on the side opposite to the first birefringent layer of the first polarizer, and the polyvinyl alcohol-based adhesive (thickness) prepared in Reference Example 3 : 0.1 μm) was performed in the same manner as in Example 1 except that the bonding was performed.
(Evaluation)
About the obtained liquid crystal panel (2C), the contrast was calculated | required according to said evaluation method. The results are shown in Table 1. Further, knick evaluation was performed according to the above evaluation method. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, Example 1 was used except that the polyvinyl alcohol-based adhesive (thickness: 0.1 μm) prepared in Reference Example 3 was used for bonding the first polarizer and the first birefringent layer. As well.
(Evaluation)
About the obtained liquid crystal panel (C1C), the contrast was calculated | required according to said evaluation method. The results are shown in Table 1. Further, knick evaluation was performed according to the above evaluation method. The results are shown in Table 1.

  According to Table 1, the liquid crystal panel using the optical film of the present invention has high contrast and good knick evaluation.

  The optical film of the present invention can be applied to a liquid crystal panel and a liquid crystal display device using the liquid crystal panel, which are suitable for a liquid crystal television and a mobile phone.

It is a schematic sectional drawing of the liquid crystal panel by preferable embodiment of this invention. When the liquid crystal display device of this invention employ | adopts a VA mode liquid crystal cell, it is a schematic sectional drawing explaining the orientation state of the liquid crystal molecule of a liquid crystal layer. When the liquid crystal display device of this invention employ | adopts the liquid crystal cell of OCB mode, it is a schematic sectional drawing explaining the orientation state of the liquid crystal molecule of a liquid crystal layer. It is a schematic diagram explaining the azimuth angle and polar angle in the measurement of a color shift. (A) is a schematic sectional drawing of the conventional typical liquid crystal display device, (b) is a schematic sectional drawing of the liquid crystal cell used for this liquid crystal display device.

Explanation of symbols

Reference Signs List 30 first polarizer 40 liquid crystal cell 50 second polarizer 60 first birefringent layer 70 second birefringent layer 100 liquid crystal panel

Claims (9)

A transparent protective film, a polarizer, and a birefringent layer composed of a cyclic olefin-based film in which the Nz coefficient defined by Nz = (nx−nz) / (nx−ny) has a relationship of 1 <Nz ≦ 2 are included in this order, polarizer and Ri Na is directly laminated on the birefringent layer through a polyvinyl alcohol-based adhesive containing a metal compound colloid, the average particle diameter of the fine particles forming the metal compound colloid is Ru 1~50nm der , Optical film.   The optical film according to claim 1, wherein the transparent protective film is either a cellulose film or an acrylic film.   The optical film according to claim 1 or 2, wherein an absorption axis of the polarizer and a slow axis of the birefringent layer are substantially orthogonal to each other.   The optical film according to claim 1, wherein the birefringent layer is a λ / 4 plate.   A liquid crystal panel comprising a liquid crystal cell and the optical film according to claim 1 disposed on a viewing side of the liquid crystal cell.   The liquid crystal panel according to claim 5, wherein a birefringent layer having a relationship of nx = ny> nz is disposed on the backlight side of the liquid crystal cell.   The birefringent layer having a relationship of nx = ny> nz includes at least one non-liquid crystal material selected from polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide. LCD panel.   The liquid crystal panel according to claim 5, wherein the liquid crystal cell is in a VA mode or an OCB mode.   A liquid crystal display device comprising the liquid crystal panel according to claim 5.

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